Reaction Injection Molding. Polymer Chemistry and Engineering 9780841208889, 9780841211001, 0-8412-0888-3

Table of contents :
Title Page ......Page 1
Half Title Page ......Page 3
Copyright ......Page 4
ACS Symposium Series......Page 5
FOREWORD......Page 6
PdftkEmptyString......Page 0
PREFACE......Page 7
1 The Future of RIM in the United States......Page 8
Literature Cited......Page 19
2 Polyurethane RIM: A Competitive Plastic Molding Process......Page 20
Assumptions......Page 22
Raw Material Costs......Page 23
Process Energy......Page 24
Hourly Labor Cost......Page 25
Capital......Page 26
New Rim Technology......Page 27
Literature Cited......Page 29
3 Phase Separation Studies in RIM Polyurethanes Catalyst and Hard Segment Crystallinity Effects......Page 30
Experimental......Page 32
Results......Page 36
Discussions......Page 48
Acknowledgments......Page 52
Literature Cited......Page 53
4 Investigations of the Structure-Property Relationships for RIM Polyurethane Elastomers Effect of an Amine Additive......Page 55
Experimental......Page 58
Literature Cited......Page 66
5 Effect of Urethane RIM Morphology on Deviation from Second-Order, Straight-Line Dependence......Page 67
Experimental......Page 69
Results and Discussions......Page 76
Literature Cited......Page 83
6 Structure-Property Relationships in RIM Polyurethanes......Page 85
Description and Operation of RIM Equipment......Page 86
Unfilled RIM-PU Materials......Page 91
Literature Cited......Page 97
7 Rheology of Polyols and Polyol Slurries for Use in Reinforced RIM......Page 99
Measurements of Fibre Packing Fraction......Page 100
Modified Cone and Plate Viscometry......Page 102
High-Shear RRIM Viscometer......Page 107
Acknowledgments......Page 110
Literature Cited......Page 112
8 Organotin Catalysis in Urethane Systems......Page 113
Results and Discussion......Page 114
Literature Cited......Page 123
9 The Ketene Aminal-Isocyanate Reaction and RIM Systems......Page 124
I· Chemistry of the Ketene Aminal/Isocyanate Reaction......Page 125
II. Solution and Bulk (RIM) Polymerizations Using Ketene Aminals......Page 128
EXPERIMENTAL......Page 132
Literature Cited......Page 133
10 Nylon 6 RIM......Page 134
Anionic Polymerization of Caprolactam......Page 135
Nylon 6 Reactive Molding......Page 137
Chemistry......Page 141
Properties......Page 143
Heat Resistance......Page 145
Moisture Effect......Page 148
Molding Processes......Page 149
Reaction Injection Molding......Page 153
Equipment Requirements......Page 157
Low-Pressure Casting......Page 159
Literature Cited......Page 160
11 Activated Anionic Polymerization of ε-Caprolactam for RIM Process......Page 162
Experimental......Page 164
Molecular Mass Distribution......Page 165
Side Reactions and Structural Irregularities......Page 170
Polymerization Kinetics......Page 173
Literature Cited......Page 177
12 Properties and Morphology of Impact-Modified RIM Nylon......Page 179
Morphology......Page 180
Results and discussion......Page 183
Literature Cited......Page 188
13 Self-Releasing Urethane Molding Systems: Productivity Study......Page 190
Commercial IMR Products and Self-Releasing Systems......Page 192
Performance Features......Page 193
Theoretical Considerations......Page 196
Production Optimization......Page 200
Literature Cited......Page 206
14 Improved RIM Processing with Silicone Internal Mold Release Technology......Page 208
Major RIM Developments......Page 209
Need For Internal Mold Release......Page 211
Organic-Silicone Hybrid Technology......Page 212
First Successful Silicone-Organic Hybrid IMR......Page 213
Advances In Silicone-Organic Hybrid IMR Agents......Page 216
Summary ......Page 217
Literature Cited......Page 218
15 Fiberglass Reinforcements in RIM Urethanes......Page 220
Experimental......Page 223
Results and Discussion......Page 224
Conclusions......Page 229
Literature Cited......Page 231
16 Mold Filling with Polyurethane......Page 232
Filling the mix into the mould......Page 233
Direct gating......Page 234
Improved fan gate (IKV version)......Page 236
After-mixers......Page 242
Filling pattern method......Page 245
Literature Cited......Page 252
Impingement Mixing......Page 254
Small Size Rim Mixing Head......Page 256
Minimum Capacity For The Processing Of Solid Filled System (RRIM)......Page 257
Low And Medium Capacity RIM and RRIM Machines......Page 262
RIM And RRIM Machines For The Processing Of Nylon And Epoxy Formulations......Page 264
Free Pour Impingement Mixing Head......Page 266
Literature Cited......Page 272
18 Profiles of Temperature and State of Cure Developed Within Rubber in Injection Molding Systems......Page 273
THEORETICAL......Page 274
EXPERIMENTAL......Page 275
RESULTS......Page 276
NOMENCLATURE......Page 284
LITERATURE CITED......Page 285
Author Index......Page 286
A......Page 287
D ......Page 288
I ......Page 289
N ......Page 290
P ......Page 291
T ......Page 292
X ......Page 293

Citation preview

Reaction Injection Molding

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

ACS

SYMPOSIUM

SERIES

270

Reaction Injection Molding Polymer Chemistry and Engineering Jiri

E. Kresta, EDITOR University of Detroit

Based on a symposium sponsored by the Division of Polymeric Materials Science and Engineering at the 186th Meeting of the American Chemical Society, Washington, D.C., August 28-September 2, 1983

American Chemical Society, Washington, D.C. 1985

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

Library of Congress Cataloging in Publication Data Reaction injection molding. (ACS symposium series, ISSN 0097-6156; 270) Includes bibliographies and indexes. 1. Injection molding of plastics—Congresses. I. Kresta, Jiri E., 1934. II. American Chemical Society. Division of Polymeric Materials: Science and Engineering. III. American Chemical Society. Meeting (186th: 1983: Washington, D.C.) IV Series TP1150.R44 1984 668.4'1 ISBN 0-8412-0888-3

Copyright © 1985 American Chemical Society All Rights Reserved. The appearance of the code at the bottom of the first page of each chapter in this volume indicates the copyright owner's consent that reprographic copies of the chapter may be made for personal or internal use or for the personal or internal use of specific clients. This consent is given on the condition, however, that the copier pay the stated per copy fee through the Copyright Clearance Center, Inc., 21 Congress Street, Salem, M A 01970, for copying beyond that permitted by Sections 107 or 108 of the U.S. Copyright Law. This consent does not extend to copying or transmission by any means—graphic or electronic—for any other purpose, such as for general distribution, for advertising or promotional purposes, for creating a new collective work, for resale, or for information storage and retrieval systems. The copying fee for each chapter is indicated in the code at the bottom of the first page of the chapter. The citation of trade names and/or names of manufacturers in this publication is not to be construed as an endorsement or as approval by ACS of the commercial products or services referenced herein; nor should the mere reference herein to any drawing, specification, chemical process, or other data be regarded as a license or as a conveyance of any right or permission, to the holder, reader, or any other person or corporation, to manufacture, reproduce, use, or sell any patented invention or copyrighted work that may in any way be related thereto. Registered names, trademarks, etc., used in this publication, even without specific indication thereof, are not to be considered unprotected by law. PRINTED IN THE UNITED STATES OF AMERICA

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

ACS Symposium Series M. Joan Comstock, Series Editor Advisory Board Robert Baker

Robert Ory

U.S. Geological Survey

Martin L. Gorbaty Exxon Research and Engineering Co.

Geoffrey D. Parfitt

Roland F. Hirsch

James C. Randall

U.S. Department of Energy

Carnegie-Mellon University

Phillips Petroleum Company

Herbert D. Kaesz

Charles N. Satterfield

University of California—Los Angeles

Massachusetts Institute of Technology

Rudolph J. Marcus

W. D. Schultz

Office of Naval Research

Vincent D. McGinniss Battelle Columbus Laboratories

Donald E. Moreland

Oak Ridge National Laboratory

Charles S. Tuesday General Motors Research Laboratory

Douglas B. Walters

USDA, Agricultural Research Service

National Institute of Environmental Health

W. H. Norton

C. Grant Willson

J. T. Baker Chemical Company

IBM Research Department

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

FOREWORD The ACS S Y M P O S I U M SERIES was founded in 1 9 7 4 to provide a medium for publishing symposia quickly in book form. The format of the Series parallels that of the continuing A D V A N C E S EST C H E M I S T R Y SERIES except that in order to save time the papers are not typese mitted by the author viewed under the supervision of the Editors with the assistance of the Series Advisory Board and are selected to maintain the integrity of the symposia; however, verbatim reproductions of previously published papers are not accepted. Both reviews and reports of research are acceptable since symposia may embrace both types of presentation.

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

PREFACE THE

N E W E S T P O L Y M E R P R O C E S S I N G M E T H O D , reaction injection molding

( R I M ) , is based on the injection of monomers or reactive oligomers into a mold, followed by a fast polymerization reaction. The attractiveness of the R I M process is its economics—savings in energy and capital investments— compared to other polyme processin methods Originally th R I M tech nology used principles of polymer R I M systems emerged, such as nylons, polyureas, polydicyclopentadienes, polyesters, and epoxies. The automotive industry's strong interest in the R I M process has been the main thrust behind the development of new R I M systems. The replace­ ment of steel body parts with glass-reinforced R I M panels could significantly decrease the weight of cars and thus improve their fuel economy. Efforts are now concentrated on improving the thermal and mechanical properties plus the dimensional stability of the polymer R I M systems, including improve­ ments in processing aspects such as unmolding, curing, and paint-adhesive­ ness. The first part of this book describes future trends of R I M in the United States and compares the economics of R I M and other polymer processing methods. The second part of the book is devoted to the polymer chemistry and physics of urethane R I M systems. In this section, variables affecting the morphology, structure, properties, and catalysis of urethane R I M systems are discussed. The new nonurethane R I M systems are covered in the third section, which includes studies on ketene-aminals, nylon polymerization, morphol­ ogy, and new research trends. The last part of the book covers the various aspects of R I M technology, such as mold release, glass-fiber reinforcement, mold filling, and new devel­ opments in R I M equipment. Finally, I would like to thank all contributors for their efforts and all A C S editors for their patience and helpfulness in processing the manuscripts. J I R I E. K R E S T A

University of Detroit September 4, 1984 ix In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

1 The Future of RIM in the United States 1

L. M . ALBERINO and T. R. M c C L E L L A N

2

1

2

D. S. Gilmore Research Laboratories, The Upjohn Company, North Haven, CT 06473 Polymer Chemicals Division, The Upjohn Company, LaPorte, T X 77571

In organizing thi material development RIM area were considered and the relationship that the market place has had as a driving force to these developments was investigated. Therefore, in considering the current and future market figures in the RIM area, an attempt has been made to relate these to further process and material developments. This paper i s organized into three parts: FIRST: Predicted RIM usage figures and other market information. SECOND: Recent and future material developments for RIM processable systems. THIRD: Process developments - including equipment developments and RIM process R & D which i s leading to a better understanding of the RIM process.

With various modifications to handle RRIM, and with further modifications to be discussed later to handle solid components, the RIM process consists of (1) high pressure metering, (2) impingement mixing, and (3) a self-cleaning mix head. It should be remembered throughout the discussions in this paper that RIM i s a process and not a material. In looking at market figures and projections for future volumes, three (3) facts emerge. (1) The automotive market i s currently the largest area of use

0097-6156/85/0270-0003$06.00/0 © 1985 American Chemical Society

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

REACTION INJECTION MOLDING

4

for REM products and w i l l continue to dominate in total volume for the next 5 years. (2) Industrial consumer applications (sometimes called nonautomotive) are predicted to grow at a faster annual rate than automotive areas - but they are starting from a much smaller base. (3) Market figures from different sources generally do not agree with each other. Agreement usually i s fairly close in the automotive area and much further apart in the industrial consumer areas probably because the industrial consumer segment i s dealing from a smaller base with many more varied and newer applications whose future i s more d i f f i c u l t to project. Some recent market figures (1) for the automotive area are shown in Table I. TABLE I. AUTOMOTIVE RIM AND RRIM (1)

Million Pounds 1982 Model Year RIM ELASTOMERS RRIM INFERIOR TRIM FOAM

32 0.1 13 to 15

1984 Model Year 53 8.6 17 to 19

These figures are for domestic passenger car production. The figures for Elastomer in automotive are primarily fascia. RRIM i s high modulus glass f i l l e d material and in the future includes reinforced fascia. Interior trim foam figures are for those made via RIM. Other sources have listed the automotive RIM market at approximately 41 MM lbs. in 1982 (BCC) growing to nearly 95 Ml lbs. in 1987, while s t i l l another study reports ~ 5 9 mm for automotive elastomers in 1982 -(Plastics Technology). This last figure of 59 Mfl lbs. includes application in buses, trucks, and recreational vehicles. Table II gives data for industrial consumer products. The types of applications in these areas have been discussed previously (2) but include such markets as electronic cabinetry, recreational, shoes, agricultural and various appliances.

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

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ALBERINO AND McCLELLAN

The Future of

5

RIM

TABLE II. INDUSTRIAL CONSUMER RIM MARKETS (1) Million Pounds 1982 ELASTOMERS URETHANE STRUCTURAL FOAM

1 6 to 9

1985 5 12 to 15

Other sources have put the INDUSTRIAL CONSUMER elastomer figures for 1982 at 7 Ml lbs and figures for 1987 as high as 200 MM lbs. have been A l l the market figures in the RIM area well above the growth figures for other processes. An indication of further growth are figures for RIM equipment, as shown in Table III. Tftese figures are for actual high pressure units (not-self contained molds). Taken in conjunction with the volumes a l l the above figures indicate strong market forces to fuel further developments in the area of materials and process research. TABLE III. RIM EQUIPMENT NUMBER OF RIM MACHINES IN PLACE 1982

1984

1987

400

475

700

In reviewing the material developments, we chose to look at the types of materials from a polymer physics or engineering point of view. Historically, the major growth in RIM has been with urethane segmented block copolymers. Specifically, because of the automotive applications these have been elastomers with approximately 50% hard segment levels. Hard segments (3) are the reaction product of the isocyanates and the extender (such as ethylene glycol or 1,4 BDO). Continued growth i s seen in this area - whether the extender i s a glycol or amine - with most of the growth for this type of elastomer being in automotive applications. However, other ranges of hard segment levels for

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

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REACTION INJECTION MOLDING

urethanes as well as non-urethane are emerging in new applications for automotive as well as non-automotive· Therefore, as a means of organizing materials by structure and morphology, rather than strictly by application, the discussion on materials development has been divided into three groups: Group 1: Hard segment levels 65% hard segment. Part of the reason for doing this i s because these types of materials generally are processed somewhat differently, in formulating the polymers emphasis i s given to different parameters, and in general, the overall markets are in different application areas. Table IV shows a breakdown by hard segment level for these different materials and polyurea urethane Table V shows general features of Engineering Rubbers (high performance elastomers) produced via RIM. These are materials which would have outstanding dynamic mechanical properties allowing then to be used in applications which demand excellent fatigue resistance and minimum heat build-up with cycling. The market figures also include some elastomers which would not qualify for the above definition -however, they are included in this group because of the hard segment level. Historically, the lower modulus (~ 90A, 30-40% hard segment) end of the market has been served by cast urethanes especially the amine cured prepolymer types. This area i s expected to see further growth for RIM, part of which w i l l come at the expense of cast systems (4). Many new formulations with improved properties w i l l become possible through the use of "HOT RIM" equipment which w i l l allow low melting solid isocyanate MDI prepolymers to be used along with low melting solid polyols in the "B" side. Going up somewhat in hard segment content to the 50-60% range affords ( at least in polyur ethane or urea-urethane RIM) the elastomers and 'elastoplastics', or perhaps a better word than elastoplastics would be toughened plastics. Table VI contains the general properties for 50-60% HARD SEGMENT polymers. This table contains polymers which have been developed in the past such as the Polyurethanes in the 55 to 65 Shore D hardness (Fascia materials), as well as Poly(ureaurethanes) which are more recent developments. This hard segment range also covers 65 to 75D intermediate modulus materials which are in reality toughened plastics. The raw materials prices are for comparison purposes. Tables VII and VIII summarize present and future RIM engineering plastic developments. This i s an emerging area for RIM processable materials part of which w i l l be made possible by recent equipment developments such as hot RIM .Polyurethane materials which now exist in this hard segment range are plastics

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

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The Future of RIM

TABLE IV. RIM (SEGMENTED) POLYURETHANE VOLUMES Million Pounds % HARD SEGMENT

1982

1987

LESS THAN 50 50 to 60 GREATER THAN 65

44.5 33.9 0.30

66.8 89.8 3.2

TABLE V. ENGINEERING RUBBERS ( HIGH PERFORMANCE ELASTOMERS) PRODUCED VIA RIM Polyurethane SHORE A RANGE T , °c

40 to 95 - 70 to -20

RESILIENCE(Rebound,%) 100% TENSILE MODULUS,psi DIE "C" TEAR,pLi USE TEMPERATURE LIMIT,°C R.M. COST, $/lb.

20 to 70 200 to 1200 100 to 450 120 0.80 to 1.60

G

urethane 40 to 95 -70 to -20 40 to 70 200 to 1200 100 to 450 140* 1.00 to 1.80

*Flatter Modulus - Temperature Profile

TABLE VI. ELASTOMERS/ELASTOPLASTICS (50 to 60% HARD SEGMENTS)

SHORE D RANGE FLEXURAL MODULUS,psi

Polvurethane

Polyurethane

Poly(ureaurethane)

55 to 65

65 to 75

55 to 65

25 to 50,000

FLEXURAL MODULUS RATIO(-30°C/70°C) 4.5 to 5.5 AUTOMOTIVE HEAT SAG 4", 1 nr.,1200C 0.3 to 0.4

50 to 100,000 4 to 5 0.2

NOTCHED IZOD,ft-lb/In

10 to 20

APPROXIMATE R.M. COST $/lb.

0.80 to 1.00

0.8 to 1.00

25 to 50,000 3.5 0. 2 to 0.4

1.00 to 1.10

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

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REACTION INJECTION MOLDING

TABUS VII. ENGINEERING PLASTICS (> 65% HARD SEGMENT)

Polvurethane SHORE D HARDNESS

75

FLEXURAL MODULUS,psi

200,000

HDT,QC at 264 psi NOTCHED IZOD, ft-lb/ln

90 to 100

Needs Post Cure (Annealing)

TABLE VIII.

SHORE D HARDNESS FLEXURAL MODULUS, psi

250,000 to 330,000

374,000 to 415,000

150

64 to 102

0.80 to 1.00

1.20 to 2.65

Meeds Reinforcement For High Impact

Needs Reinforcement For High Impact

Polyester

Nylon 6 Type

Polyamide Type (Enamine)

High

70

72

196,000

182,000

High

73

NOTCHED IZOD, ft-lb./In.

COMMENTS

75 to 80

ENGINEERING PLASTICS (>65% HARD SEGMENT)

HDT,°C at 264 psi

APPROXIMATE COST $/lb.

Epoxv

0.5 t

APPROXIMATE COST, $/lb. 0.80 to 1.00 COMMENTS

Poly(urethaneIsocyanurate)

9.8 0.85 Contains Styrene

Heat Sag 325 F.,1/2 Hr. 0.23 in. LT 1.0

1.60 Moisture Sensitive Catalyst and Special Equipment

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

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RIM

with similar mechanical properties to toughened styrene and high inpact ABS (5). The urethane modified Isocyanurate material can be processed on present equipment. This material has very high modulus and very high HOT (6) with has fast demold characteristics. Unfortunately i t also has low inpact and needs long fiber reinforcement for good impact. Epoxy RIM materials (7,8) also would have high modulus and low impact and therefore would need long fiber reinforcement. Currently undergoing development are Polyester materials (Table VIII). Cost may be i t s best property (7). The nylon 6 type of material has received greatest attention in terms of commercial interest (10). However this type of material needs special equipment, has a catalyst system which i s sensitive to moisture, as well as the polymer itself being moisture sensitive. It does offer outstanding impact/thermal properties. The enamine type of material was presented several years ago (11). As i t exists now there are problems with impact. It i s however an indication in the RIM area by evaluatin A further example of the new materials research being done on RIM processable polymers are the high modulus urethane -epoxy IPN's, shown in Table IX (12). These materials are shown compared to a toughened plastic polyurethane: 146,000 psi flexural modulus urethane material. The urethane-epoxy IPN's are based on two epoxies (Bisphnol A type and Novalak type). Process developments in the RIM area have involved equipment developments, RIM Process R & D and some aspects of reinforced vs f i l l e d RIM. Since some of the emerging non-urethane based RIM materials development technology involves specialized equipment, i t would be instructive to briefly compare some of the differences in processing especially since RIM i s a process and not a material. Table X shows some of these basic differences between current RIM technology and recent Hot Rim candidates. Besides the obvious differences, . urethane processing demands exact stoichometry . current new candidates such as Nylon 6 or polyesters have no exact stoichiometry. Only the urethane modified isocyanurates which can be processed on current RIM equipment have no exact stoichiometry. Many current urethane components when mixed together are incompatible and therefore need very intensive mixing in the mixhead. In addition, aftermixers and other aspects of tool design can be very c r i t i c a l in order to insure proper mixing. Some of the new candidates appear to be more compatible in their reaction profile. Thus one should use caution when judging processing of 'urethane' type systems on equipment designed specifically for other polymers -RIM s t i l l i s intensive mixing. Historically, many new polymer technologies have developed through experimental means such as applications and product development. Such i s the case also with RIM. Only fairly recently has process research been performed on the RIM process which has led to a more fundamental understanding of the process as a whole. RIM process research has been divided into three

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

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REACTION INJECTION M O L D I N G

TABLE IX. HIGH MODULUS URETHANE-EPOXY IPN'S

Urethane 30:70 Diol:Polyol

Urethane BPA EPOXV

50.4

IsonateR 191 (1) 49.5

39.6

78

Flexural Modulus, psi 145,000

40.3

40.3

Epoxy Hardness Shore D

Urethane Novalak Epoxy

39.6

20.0

20.0

65

83

231,000

244,000

Izod Notched Inpact ft-lb/In 6. Elongation at Break

20

30

10

TABLE X. BASIC DIFFERENCES BETWEEN CURRENT RIM TECHNOLOGY AMD RECENT "HOT RIM" CANDIDATES OBVIOUS DIFFERENCES SUCH AS: •

Solid Components

•

High Mold Temperatures

•

Heat Traced Lines and Pumps

•

Slower Cycle Times OlMER DIFFERENCES

•

Urethane Processing Demands Exact Stoichiometry

•

Current New Candidates have no exact Stoichiometry or are much less sensitive to stoichiometry

•

Many urethane components are incompatible and need very intensive mixing

•

Current new candidates are more "compatible" and mix easier -may not need an aftermixer

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

1. ALBERINO AND McCLELLAN

The Future of RIM

11

"unit" operations; (1) the mixing process, (2) Reaction kinetics and heat transfer modeled for the RIM process, and (3) mold f i l l i n g studies. Figure 1 summarizes impingement mixing i n the RIM process as described by Macosko and coworkers (13). The "quality" of mixing i s improved by making the striation thickness small enough so that diffusion occurs rapidly. The mixing quality was found to correlate with the Reynolds Number (N^g). Good mixing occured for N R E of 200. As more information of this nature i s gained on the mixing process, a better understanding of the relationship between material mixed in the mix head to material exiting the after mixer w i l l result. Understanding the reaction and heat transfer processes in the RIM Process has led to models which can predict tenperatures in a RIM molded part and through kinetics the monomer conversions can be measured as a function of in mold dwell times. Temperature profiles at various depths in the molded part can be predicted and correlated with processin as this should aid the by allowing them to account for the effect of different températures in the molded item due to thickness differences affects such as too high exotherm temperature causing blistering and polymer degradation, stresses due to thermal effects, too rapid crystallization - or no crystallization due to temperature extremes. The third "unit operation" process currently under study i n RIM i s the mold f i l l i n g process (15) · Measuring the pressure drop in the mold f i l l i n g step allows the calculation of the viscosity. Two cases exist; that where viscosity i s constant ( l i t t l e or no reaction) and the case where viscosity i s a function of temperature and conversion. Hie latter case requires a numerical solution to determine the viscosity. The type of information that can be gained from these studies i s directly relatable to how well a material w i l l RIM process in a tool -again this type of information should aid in tool design. An area of RIM which very rapidly advanced through machinery and equipment developments i s the so called REINEORDCED RIM or (RRIM) technology now an accepted and proven commercial process after only several years of intense machine development (16). The kinds of solid additives which in reality can be processed on RRIM equipment are f i l l e r s not reinforcing agents, due to their low aspect ratio. The RIM process as i t now stands, either as RIM or RRIM puts limitations on the type of material that could advantageously be used in the process. One must use a material with a certain level of toughness in order to obtain useful structural parts. Table XI demonstrates the effect of fiber length on properties for a type of RIM processable material - the urethane modified isocyanurate which has low impact. Table XI compares milled glass fibers with 1/8" chopped strand. The longer aspect length chopped strand provides for true reinforcement. However, i t cannot be used in current RRIM equipment. The use of long fibers - such as in continuous strand mat (RIM Mat Molded) affords composite material with potentially

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

REACTION INJECTION MOLDING

MICROSCOPIC

MACROSCOPIC

Ο TYPICAL URETHANE SYSTEM WITH - 6 SBC GEL,

RE =200 critical RE

< 200 = ^ Diffusion control of reaction rate.

RE

>200

^ K i n e t i c control of reaction rate.

O IN A DIFFUSION CXWTRQLI£D SYSTEM, THE FASTER THE GEL TIME, THE BETTER THE MIXING MUST BE. BETTER MIXING -> SMALL STRIATION THICKNESSFASTER DIFEUSION F i g u r e 1.

Impingement m i x i n g i n the £IM p r o c e s s

(13).

TABLE XI. EFFECT OF GLASS FIBER LENGTH ON IMPACT STRENGTH

A. Milled Glass Fiber (RIM; Admiral) Unfilled Izod Gardner

1.2 0.8

15% Glass 0.5 0.3

B. 18" Chopped Strand (Compression Molded) Izod Gardner

0.5 0.3

1.8 0.2

C. Continuous Strand Mad (RIM; DSG-395-12) Izod Gardner

0.4 0.3

9.4 1.0

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

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The Future of RIM

very useful properties. Unsaturated polyester and many epoxies would be in this same situation. Mat molding points up an area of future R & D using the RIM process. RIM mat molding - a kind of RIM RUM process - while s t i l l in the early stages of development may hold the promise of providing SMC like materials through the RIM process. Table XII further illustrates some of the properties achievable with this technique. Other developments for RIM in the future include Internal Mold Release - the successful application of this technology should bring the overall cycle-time for a RIM process down to that of thermoplastic injection molding. In summary, the future of the Reaction Injection Molding process in the USA definitely appears to be extremely positive. Fueled by growing market awareness and interest, especially in the Inudstrial Consumer area, new material and process developments should bring forth a variety of new applications. The automotive market for RIM continues to be strong, and for the near term w i l l be the major driving forc

TABLE XII. RIM MAT MOIDING WITH DBG 395-12 SYSTEM % GLASS

0

25

33

LAYERS OF MAT

2

3

LAYERS OF VEIL

2

2

1.33

1.24

85

84

PROPERTIES SPECIFIC GRAVITY

1.16

SHORE D

83

FLEXURAL STRENGTH,psi FLEXURAL MODULUS,psi NOTCHED IZOD,Ft-lb/In.

9,300

16,500

23,300

248,000

610,000

715,000

0.5

7.9

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

11.0

14

REACTION INJECTION MOLDING

Literature Cited 1. 2.

3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13.

14.

15. 16.

The Upjohn Co., Polymer Chemicals Div., LaPorte, TX. L. M. Alberino, "Future of RIM Development in the U.S.A. in the 1980's", Polymer Sci & Tech. 18, Reaction Injection Molding and Fast Polymerization Reactions, Ed. J . E. Kresta, Plenium Press (NY). R. J . Lockwood and L. M. Alberino, p. 363 "Urethane Chemistry and Applications", Κ. N. Edwards, ACS SYMPOSIUM SERIES No. 172, American Chemical Society, Washington, D.C., 1981. T. R. McClellan, "The MDI Bridge", Polyurethane Manufacturers Association, San Diego, Nov. 4, 1979. Upjohn Data, D. S. Gilmore Research Labs., North Haven, CT, 06473. P. S. Carleton, D. J . Breidenbach, and L. M. Alberino, 1979 NATEC, SPE(1979), Detroit, MI. Shell Chemical Co. Technical Bulletin 56: 513-81R W Saidle and R. L. Mitchell R. S. Kubiak and R MI. G. M. Peters, 38th Annual Conference SPI RP/C Proceedings, Feb. 7-11, 1983, Houston, TX. Plastic Technology, p. 22, 28 (9) August 1982. D. F. Regelman and L. M. Alberino, "Organic Coatings and Plas­ tics Chemistry", American Chemical Society, Atlanta, GA (1981). Pearce et a l , Organic Coatings and Plastics Chemistry, 45, 279 Aug. 23-28, 1981 (NY). P. Kolodziej, C. W. Macosko, and W. E. Ranz, "The Influence of Impingment Mixing and Stiration Thickness Distribution and Properties in Fast Polyurethane Polymerization". J . Polymer Eng's and S c i . , 22 (6) April 1982. N. P. Vespoli and L. M. Alberino, "Computer Modeling of the Heat Transfer Processes and Reaction Kinetics of Urethane Modified Isocyanurate RIM Systems", AICHE Diamond Jubilee Meeting, Washington, D.C. Nov. 1 & 2, 1983. J . M. Castro and C. W. Macosko, "Studies of Mold F i l l i n g and Curing in the Reaction Injection Molding Process," AICHEJ., 28 No. 2 250 (1982). P. Z. Han, 37th Annual Conference RP/C Institute SPI, Jan. 1115, 1982, Washington, D.C.

RECEIVED

April 30, 1984

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

2 Polyurethane RIM: A Competitive Plastic Molding Process Ε. T. L L O Y D andM.C.C O R N E L L The Dow Chemical Company, Freeport, T X 77541

Extensive use of flexible polyurethane fascia on automobiles has established RIM (Reaction Injection Molding) as a viabl Improvements in this process are continuously occurring which increase productivity, versatility, and the competitive economics of RIM versus other plastic molding techniques such as compression molding or thermoplastic injection molding. This paper examines the relative economics of state-of-the-art RIM versus these other molding techniques to make large, complex parts. Factors considered include productivity, raw material consumption and cost, process energy, tooling, fixturing, hourly labor and capital. Developments in RIM technology such as internal mold release promises to further increase the attractiveness of the RIM process. The growth of reaction Injection molding (RIM) has been quite dramatic since the commercialization of this process 1n the mid-1970's. Forecasts by Dow and others Indicate that this growth rate will continue over the next several years due to emerging new applications, both within and outside the transportation Industry. Certainly, a primary reason for this growth stems from the bottom Une economic advantage in producing large parts via the RIM process versus other plastic fabrication techniques. This economic advantage results from the attributes of the RIM process, which Include simple, fast mixing of highly reactive liquid components and the elimination of a messy and time consuming solvent flush between shots which Is common with mechanical mixing dispensing equipment. Because the tool 1s filled with liquid monomers, RIM allows the production of both large and complex shapes using lightweight and/or lower cost clamping presses and molds; thus saving on capital. Although polyurethane has been the principle polymer commercialized in the RIM process, modified polyurethane and 0097-6156/85/0270-O015S06.00/0 © 1985 American Chemical Society

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

16

REACTION INJECTION MOLDING

non-polyurethane RIM systems are rapidly moving toward commercialization. Polyurethane RIM (PU-RIM) was selected for the Initial RIM application of automotive fascia not only because 1t provides the required damage resistance and other performance requirements, but also because the reactivity of the urethane raw materials, Isocyanate and polyol, provide acceptable productivity. Because the urethane mnomers can be nucleated, high quality sink free surfaces that are suitable for automotive exteriors are produced at the time of demold. Little, 1f any, post mold surface repair 1s needed In preparation for painting the RIM part. PU-RIM 1s most advantageous 1n molding large, complex parts where surface quality and damage resistance are Important, I.e. automotive fascia and nonstructural body panels. It 1s also a more efficient process than casting for molding smaller sized but large volume elastomer1c Items such as shoe soles, beer barrel skirts and window gaskets. This paper will explore the effect of these attributes toward making the RIM process competitiv techniques. It will also Illustrate the Impact that pending developments in RIM technology, such as Internal mold releasing systems, will have in making PU-RIM even more economically viable. For this case study, a vertical body panel such as that being molded of glass reinforced polyurethane-RIM (PU-RRIM) for the Pontiac Fiero fenders and door panels was chosen. The average projected surface area for a typical fender and door panel 1s about 750 sq. 1n. and 1,000 sq. 1n. respectively. The fender was selected for this study. A body panel was chosen as our target application because major plastic molding techniques: RIM, compression molding and injection molding can be used to fabricate these parts. With the appropriate polymer system all three processes can be used to mold parts which essentially meet performance requirements. For RIM the chosen standard 1s the typical glass filled polyurethane system now being used. Injection molding 1s represented by a polycarbonate -polybutyleneterephthalate blend (PC alloy). For compression molding, a low profile SMC composition 1s our standard. Typical compositions of these plastics are shown in "Table I". Table I. PU-RRIM PC ALLOY "SMC

-

Typical Material Compositions, {%)

Polyol 27.9 - Isocyanate/MDI Based 43.6 Ethylene Glycol 8.4 - Fiberglass 20.0 Catalyst 0.1 Bis A/Phosgene Polycarbonate Î2" Polybutyleneterephthalate Polyester 53 Polybutadiene 4 Polyester Resin 15 - Magnesium Oxide ? Calcium Carbonate 35 - Styrene 1.7 Glass Fiber 30 - Zinc Stéarate 1 Low Profile Agent 7 - Catalyst .3 Polyethylene 4_

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

2. LLOYD AND CORNELL

A Competitive Plastic Molding Process

17

Performance requirements for other large plastic parts like fascia, hoods, and deck 1 Ids would most likely eliminate one or another of these polymers and/or molding processes from consideration. For example, SMC is not considered to have sufficient impact resistance for fascia; and RIM and engineering thermoplastic materials have yet to be developed for structural applications which also require a high surface quality, i.e. hoods and deck lids. These other parts were thus not chosen for this study. As in any economic study certain assumptions must be made. It is not the intent of this paper to analyze cost factors 1n fine detail, but rather to examine and compare the major direct cost contributors in molding large plastic parts by these major process techniques. These direct cost factors are productivity, raw materials, process energy, tooling, fixturing, hourly labor and capital. Indirect costs that are based on these direct cost items are not considered 1n this study. Such indirect Items Include supervision, maintenance and building depreciation In addition to Dow's own technology base in RIM, injection molding and compression molding, the data in this study was developed from literature references and from consultation with authorities in the automotive Industry, material suppliers and equipment manufacturers. Assumptions It 1s assumed that the body panel will be made in an existing fadlty of a medium sized molder having state-of-the-art equipment. For RIM, a typical plant was deemed to have twelve clamps with one metering unit and glass dispersion unit servicing four clamps. Such RIM plants are indeed typical of the industry. The comparable output for a SMC operation would employ 13 clamp units. A comparable output in an Injection molding operation would require seven large extruders of at least 2,500 ton clamping capacity. While very few Injection molders in North America have this capability, a seven unit injection molding line was assumed for this study. These "typical" operations were determined as a basis for spreading direct capital Items, such as bulk handling and storage systems, which were common to the entire plant. The plants are assumed to be operating at capacity, making the fullest utilization of capital over a 48 week/year production schedule operating three shifts/day and five days/week (annual operating hours @ 5,760). A minimal amount of production overtime to meet demand was assumed if this was cost effective versus purchasing additional tooling. Labor was calculated at $20.00/hour over 52 weeks. A demand of 200,000 of these 750 square Inch body panels was assumed for a model year. Costs for painting are assumed to be constant and are not considered In this study. Rather costs are calculated to produce the body panel ready for the painting operation, Including any surface preparation and repair that might be required.

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

18

REACTION INJECTION MOLDING

Direct Cost Factors Productivity Productivity factors are shown 1n "Table II". With today's technology, 1t 1s possible to operate both SMC and Injection molding clamps during an entire shift. However, because RIM requires frequent application of an external mold release, approximately one hour per shift 1s required to perform both major and minor cleaning of the tool. Thus for RIM, only an 87.5% process efficiency was assumed. Table II.

Productivity (200,000 Parts/Year)

Scrap Rate, % Production Demand, M Cavities/Mold Cycle Time, Sec. Annual Capacity, M Efficiency, % : Process : Operating Clamp Output, M Clamps/Production Demand Molds

SMC

PC ALLOY 3

PU-RRIM Ζ

150 138.2

90 230.4

120 172.8

100 80 110.6 1.86 2

100 80 184.3 1.12 1

87.5 80 121.0 1.69

3

2

Operating Inefficiencies of 20% are assumed by the automotive Industry due to maintenance, tool changes, absenteeism, and other unscheduled Interruptions. Clamp output 1s defined as the annual clamp capacity less both process and operating Inefficiencies. The clamps required to meet production demand 1s the ratio of production demand/clamp output. This relationship 1s used in determining fixed cost such as tooling, flxturlng, hourly labor, and plant capital. Raw Material Costs Data summarizing raw material usage and cost development 1s provided 1n "Table III". Raw material usage 1s based upon part weight, material waste, and production demand. Today, body panels of PU-RRIM and PC alloy are molded at thicknesses of .125 Inch. Due to the higher flexural modulus of SMC, such parts are molded with the thickness reduced to .100 Inch. Thickness reductions are projected for all materials, however such speculative material use reduction measures were not considered. Waste material can be generated either as raw material loss, part trimmings or defective parts. In the case of PC alloy, the waste aenerated from trlmmlna (approximately 10% of Injection weight) and defective parts (approximately 3%) 1s recoverable via grinding and reprocessing. Recoverable waste was thus not considered as a factor when evaluating PC alloy material usage.

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

2.

LLOYD AND CORNELL

A Competitive Plastic Molding Process

Table III. Thickness, in. Specific Gravity Part Wt. (750 In*), lbs Waste : Raw Material, % : Trim/Part, lbs : Defective Parts, % Material/Part, lbs Material/200,000 Units Cost/lb, $ Material Cost/Year, M$ Mold Release, M$ Total 9

19

Raw Materials SMC .100 1.80 4.88

—

4

PC ALLOY .125 1.22 4.13 Recoverable

3 5.23 1046 0.90 941

4.13 826 1.60 1322

941

1322

—

—

PU-ftIMH .125 1.14 3.86

—

.57 2 4.52 904 1.02 922 40 962

Trim waste (aftermlxer 10-15% of the Injection weight for PU-RRIM, and along with defective parts (2%), produce non-recoverable material which must be reflected in total material usage. Trim losses are negligible for SMC. Nonrecoverable raw material loss associated with prepreg fabrication and defective parts due mainly to poor material flow contributes about 4% and 3% respectively to the total material usage for this molding process. Material cost 1s derived from published 11st price. In the case of SMC, 1t 1s assumed that a molder of this size will purchase prepreg at $.90/lb rather than compound SMC from basic Ingredients. External mold release 1s a raw material consideration for only PU-RRIM and 1s estimated to contribute $0.20 to the overall part cost. Process Energy A comparison of energy cost for SMC, PC alloy, and PU-RRIM is shown in "Table IV". RIM compares favorably with the other process technologies. Process energy for liquid molding systems are typically lower than for injection molding systems, due primarily to reduce process temperatures. The monomers for PU-RRIM are commonly held slightly above room temperature (37 C) while mold temperatures run 70°C. These same process parameters for Injection molding are typically 300°C and 180°C respectively. Energy consumption in compression molding falls between these extremes. Table IV. Component Temperature, C Mold Temperature, °C Process Energy/lb, M BTU Material/Year, M lbs Energy Cost 0 $0.575/KWH, M$ e

Process Energy SMC 23 170 18.6 1006 315

PC ALLOY 300 180 39.0 851 559

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

PU-RftIM 37 70 16.6 904 253

20

REACTION INJECTION MOLDING

Process energy for SMC, PC alloy, and PU-RRIM is reported to be 18.6M, 39.0M, and 16.6M BTU/lb.U) The utility (electrical) rate for primary (custom or captive molder) customers in the Detroit area is reported at $.0575/k1lowatt-hour.(2) Tooling/Fixtures The evaluation of tooling and fixturing costs is summarized in "Table Y". These materials are depreciated over 1-2 years (1 year in this study) because of the frequent engineering and styling changes of the part. This cost is therefore differentiated from capital cost. Table Y. Tools Cost/Tool M$ Tool Cost, M$ Fixtures, M$ Total, M$

Tools and Fixtures SMC

PC ALLOY

PU-RRIM

600

—

250

600

250

450 75 525

—

Lower productivity of SMC and PU-RRIM is evidenced by the need for two tools to meet specified production demands of this study. It was assumed that overtime would be used rather than purchasing a second tool for PC alloy. Full part support during post cure, prime and topcoat bake required for PU-RRIM adds an additional fixed cost to this process. These support fixtures typically range from $200 - $500 each. The price used in this study is $350/fixture. Assuming fixture turnaround time of four hours, including part washing; post cure; primer and topcoat, a plant would thus require a number of support fixtures equal to four times the hourly production volume. With a clamp output of 21 parts/hour, a plant operation would require 84 fixtures. In addition, extra fixtures for reworks are needed. It was assumed that 126 fixtures would be needed by this "typical" pi ant. Hourly Labor Cost "Table YI" summarizes the derivation of hourly labor cost for typical SMC, PC alloy, and RIM operations producing 200,000 units. Manpower requirements are needed for raw materials handling, press operation, part trim, Inspection and repair. SAC manpower is allocated to raw material handling for the fabrication of the preform. Raw material handling in RIM would require manpower to formulate, disperse glass in the polyol component and chemically analyze components and formulated B-sides. Manpower allocated to material handling in an Injection molding plant would be negligible. In compression and injection molding operations the press operator demolds and trims the part. This same operator in a RIM

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

2.

LLOYD AND CORNELL

21

A Competitive Plastic Molding Process

plant demolds the part, picks any flash left in the mold and applies the external release agent. This operator is normally accompanied by a full time assistant whose responsibilities Include flash removal, void treatment and Inspection of the part 1n preparation for painting. Table Y I . Men/Press : Raw Material Handling : Press Operation : Trim : Inspect/Repair Presses Men/Shift Labor § $20/Hr, M$

Hourly Labor SMC

PC ALLOY

PU-RRIM

1.0 1.0

—

—

—

0.2 1.0 1.0 0.3 1.69 4.23

2.0 1.86 7.44

1.0

1.12 1.12

SMC typically requires post mold rework to provide a Class A surface. Consequently, additional manpower Is allocated for inspection and repair for SMC to f i l l and sand the parts 1n preparation for painting. Some manpower 1s allocated for minor repair of PU-RRIM parts. The inspect/reject function 1n an injection molding operation Is normally handled by the clamp operator. Capital "Table V I I " summarizes the cost of process equipment and associated raw material handling equipment required to process SMC, PC alloy and PU-RRIM. A range of prices as well as an average price 1s Indicated. For the purpose of this study this average price was used. Table V I I . PROCESS RIM

Compression Molding Injection Molding

Summary of Estimated Capital, $M

ITEM Material Handling Glass Dispersion/4 Clamps Metering Un1t/4 Clamps CI amps Prepreg Storage & Preform Preparation Clamp Material Handling (7 Extruders) 2,500 Ton Extruder/Clamp Grinder/3 Extruders

RANGE 225 - 435 100 - 200 100 - 200 100 - 200

AVERAGE 330 150 150 150 260

250 - 1500 250 - 310

875 280

800 - 1000 25 - 35

900 30

"Table Y I I I " summarizes the capital needs of a production

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

22

REACTION INJECTION MOLDING

facility to meet the 200,000 part production demand. The material handling and conditioning costs were amortized over the entire plant operation. Also Included are estimated installation costs based on 20% of the capital cost. These fixed costs were depreciated over seven (7) years using a straight line (SL) depredation schedule. Table VIII. Capital, $M SMC Pre-preg 40 Clamps

Raw Material Handling Process Equipment Installation 0 20% Total Capital Depreciation, 7 yrs S.L

PC ALLOY Pellet 40 Extruder/Clamp

1630 330

910 190

PU-RRIM Liquid/Filler 110 Metering Unit and Clamps 320 90

"Table IX" summarizes all of the direct costs considered in this economic model. Analysis of this data Indicates that PU-RRIM and PC alloy injection molding are the most economical polymer/processes for our body panel example. Table IX.

Raw Material Process Energy Tools/Fixtures Hourly Labor Capital Total $/Part

SMC 941 315 600 930 286 3072 15.36

Direct Cost, $M

PC ALLOY 1322 559 250 140 163 2434 12.17

PU-RRIM 962 253 525 530 74 2344 11.72

m

PU-RRIM 922 250 335 360 44 1911 9.55

PU-RRIM 801 247 335 360 44 1787 8.93

New Rim Technology Examination of the economic data Indicates several specific areas where PU-RRIM is penalized, among them are: long cycle time, process inefficiency (down time for mold clean), scrap, and the need for external mold release. These factors result in higher labor, unit capital and tooling costs for PU-RRIM when compared to Injection molding. This situation provides a chailange to make PU-RRIM more economically viable. Because of these limitations, the RIM Industry has put a high priority on the development of an effective mold release agent which can be Incorporated in the raw material component streams. An Ideal RIM Internal mold release (IMR) would essentially eliminate both the need to treat the tool between shots and mold

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

2. LLOYD AND CORNELL

23

A Competitive Plastic Molding Process

cleaning down time. This IMR should show no deterioration of component stability or other processing parameters, and not alter the physical properties of the polyurethane polymer. In particular, a RIM IMR must not interfere with the painting process nor be detrimental to paint adhesion or paint weathering characteristics. Such RIM IMR technology has been developed by Dow and is 1n the final stages of production qualification at major RIM molders. While the details of this technology are beyond the scope of this paper, the impact of an effective IMR on RIM economics can be addressed. This data is shown on "Table X", where one can see cycle times reduced from 120 seconds to 90 seconds; the elimination of nonproductive mold cleaning time; and the elimination of scrap resulting from external mold release buildup. The reduction 1n part cost is significant; the unit cost for the body panel is reduced from $11.72 to $9.55 for an 18.5% production cost reduction. Table X. ~ Increase Press Output - Cycle Time - Process Efficiency - Defective Parts — Reduce Capital - Clamps — Reduce Tooling — Reduce Labor - - Elimination of EMR

RRIM IMR 121 M 120 Sec 87.5 % 2 %

—> —> —> —> —> —> —>

176.9 90 96 1

M Sec % %

1.69 1.14 2 1 4.23 Men 2.85 Men < $0.20/Part >

In addition to IMR, another area offering economic improvement for PU-RRIM is the reduction in raw material cost via Incorporation of less expensive fillers. Today, PU-RRIM body panels use 20% milled or flaked fiberglass at $.93/lb. Alternative fillers are available at a much reduced price. For example, development work Incorporating an industrial mineral fiber, wollastinite, has shown some promise. The 11st price for wollastinite is $.25/lb. Raw material cost, on a per pound basis by substituting wollastinite for fiberglass 1s a reduction from $1.02 to $.84. The overall economic impact from both IMR and wollastinite 1s a per part manufacturing cost reduction to $8.93, and additional 5.3% over systems containing IMR alone, and a 23.8% improvement from today's technology. A summary of the economic Impact of IMR and less expensive filler (wollastinite) on the direct cost of manufacturing PU-RRIM body panels considered in this study is found in "Table IX". In conclusion, 1t has been demonstrated that existing PU-RRIM technology offers a good balance of economics, processing and performance. The pending utilization of Internal mold release will further enhance the attractiveness of the PU-RIM process. RIM technology 1s favored when the application requires large parts with complex shapes, Class A surface, and damage resistance. The

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

REACTION INJECTION M O L D I N G

24

model presented here can be utilized to evaluate the economic Impact of both material modification and process Improvements in molding large RIM articles such as body panels and fascia. Literature Cited 1. 2.

Plastic Parts by Reactive Processing - "A Technology for the Future", William L. Kelley, SAE Technical Paper Series 820419. Phone conversation with Detroit Edison.

R E C E I V E D September 28, 1984

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

3 Phase Separation Studies in RIM Polyurethanes Catalyst and Hard Segment Crystallinity Effects 1

R. E. CAMARGO , C. W. MACOSKO, M . TIRRELL, and S. T. W E L L I N G H O F F Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455

Production of polyurethane elastomers by reaction injection molding, RIM, is now a well established technique. Since RIM involves a fast exothermic polymerization erties in the materials and polymerization conditions. The particular properties of poly­ urethane elastomers derive to a large extent from phase separation into hard, crystalline or glassy regions that reinforce and the soft rubbery phase. Figure 1 gives a simplified representation of such a microstructure. The hard segments are composed of sequences of a diisocyanate reacted with a short chain diol or diamine, the extender. In the particular instance of Figure 1, the hard segments are shown as c r y s t a l l i n e , but they can also be amorphous. The soft segments are composed primarily of a long chain diol or triol (equivalent weight of 1000 or greater), and also of diisocyanate­ -extender sequences scattered throughout the matrix. Major factors affecting the final properties of the polymer are the composition and the degree of order within each phase, and the topology or connectivity of the microphase structure, i.e. sharpness of the domain boundaries and mixing of the phases. Several studies have been published in recent years on the properties of RIM polyurethanes and polyurethane-ureas (1-7). Unlike most studies, however, we have restricted our attention to simplified linear systems in order to establish the effect of reaction rates and mold temperatures on the phase separation and molecular weight of segmented polyurethane elastomers produced by RIM(6). In our earlier work, we prepared rapidly polymerized samples with high molecular weight and finely dispersed hard and soft phases of low hard segment c r y s t a l l i n i t y . A high temperature dependency of the storage modulus was characteristic of this structure. At low reaction rates the polymerization proceeded almost isothermal ly at large undercooling. Incompletely reacted, low molecular weight, oligomers of high hard segment content phase separated into large spherulitic structures, between which was isolated material of rather low fracture strength. Evidently, early formation of hard segment 1

Current address: Raychem Corporation, Corporate Technology, Menlo Park, C A 94025.

0097-6156/ 85/ 0270-0027$07.00/ 0 © 1985 American Chemical Society

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

28

REACTION INJECTION MOLDING

Figure 1. Schematic representation of the segmented micro structure in a semi crystal line polyurethane block copolymer.

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

3. CAMARGO ET AL.

Phase Separation Studies in RIM Polyurethanes

29

c r y s t a l l i t e s , can remove unreacted isocyanate groups from solution preventing further reaction with the polyol (6-8). Scope of the Present Works We have extended the previous experiments(6) to a wider spectrum of catalyst concentrations, at hard segment levels typical of those used in the production of RIM fascia automobile parts (ea. 45-50% hard segment). As in our previous work,(6) only difunctional reactants at matched stochiometries of the reactants have been used. This ensures linear, soluble polymers and al lows molecular weight characterization. To study the role of hard segment crystal 1 izabi 1 ity, two series of polymers were prepared from special reactants as described in the experimental section. In addition some comparative results have been obtained by varying the molecular weight of the polyol s used. Experimental Materials. The polyurethanes used are based on polypropylene oxide d i o l , capped with a certain amount of polyethylene oxide to provide high primary hydroxy content, and thus high reactivity. The main characteristics of the polyol s are l i s t e d in Table I. Crystal 1 izabl e hard segments were made from 4,4'-di phenyl methane di isocyanate, MDI (Rubinate 44, Rubicon Chemicals) and 1,4-butanediol, BDO (GAF Chemi­ cals) or 1,2-ethanediol, EDO (ethylene g l y c o l , Fisher Scientific). Amorphous hard segments were obtained using 2,4'-diphenyl methane diisocyanate, 24-MDI (this non-commercial material was kindly provided by Dr. D. Spence from Rubicon Chemicals) and BDO, or 44-MDI and n-methyldiethanol amine, MDEA (Union Carbide Corp.). In either case hard segment crystallization is inhibited by molecular asymmetry (24-MDI/BDO) or by branching (MDI/MDEA). The catalyst used in a l l cases was dibutyl t i n dilaurate, DBTDL (T-12, M. & T. Chemicals). Sample Identification. Given the number of samples and compositions, a general code was created as explained in Table II. In this table, the polyol type is identified by molecular weight and ethylene oxide content. Thus 40/15 refers to a polyol with Μ = 4000 and 15% (w/w) of ethylene oxide end capping agent. The last two labels in Table 2 indicate mold temperature and catalyst content. η

Reaction Injection Molding. Molded polymer samples were produced in our laboratory-size RIM machine (9). Details of reactant preparation and molding procedures are found elsewhere (9-10). B r i e f l y , the polyol and extender are blended as received at the desired stochiometry. Catalyst is added when required and the mixture *In this paper, the hard segment content is defined as the percent by weight of the isocyanate and extender in the polymer at a fixed stochiometry or isocyanate index.

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

(1) (2) (3) (4)

n

Calculated assuming hydroxyl functionality of two Data from supplier From GPC measurements Corresponds to (M /100)/(%E0)

40/15 80-85

15

1.20

4080

01 in Corp.

Poly G 55-28

23/25 80

25

1.12

ID Code 20/30

2306

(2)

Texaco Chemicals

Thanol E2103

% Primary 0 H ' s 83

28/15

( 2 )

75-80

E0

15

%M

1.15

( 3 )

2772

Union Carbide Corp.

Ni ax E-351

M

30.4

1999

Union Carbide Corp.

Ni ax 1256 (special)

2

V n 1.11

n

Supplier

„ n, ,

Characteristics of Polyols Used

Commercial Name

Table I.

(4)

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

Β)

A)

BDO = B EDO = E MDEA = M

MDI = M

AN EXAMPLE:

140

to

to 51

70

MOLD TEMPERATURE °C

48

catalyst content: 0. 03% mold wall: 70 °C hard segment: 48% polyol: 23/25 extender: EG isocyanate: MDI

20/30 23/25 28/15 40/15

(

HARD SEGMENT % 1 '

A Sample Identification Code

POLYOL TYPE

Μ - Ε - 23/25 - 48 - 70 - 3Ç

(1_) Defined in text

24-MDI = 24M

EXTENDER TYPE

ISOCYANATE TYPE

CHEMICAL CODE AND RANGE OF VARIABLES:

Table II.

75

to

00

CATALYST CONTENT 1000 χ % CAT

5"

S"

I ι

1'

I

r

>

ο ο Η

>

>

η

32

REACTION INJECTION MOLDING

subsequently degassed at room temperature for approximately eight hours. The pure MDI is melted and f i l t e r e d at ca. 50°C immediately before each run. The chemicals are loaded in the machine tanks and blanketed with nitrogen. A l l lines and tanks are kept at 55± 5°C at a l l times. During the injection cycle, the materials are injected at the rate of ca. 0.1 kg.sec" through a recirculating, self-cleansing, impingement mixing head, and into a rectangular, end-gated, tefloncoated mold (125 χ 125 χ 3 mm), opened and closed by a hydraulic press. Mold temperature is maintained by means of electrical resis­ tances. The mold temperature in most runs was kept at 70°C. After demolding, the polymer plaques were postcured in an oven at 120°C for 1 hour, and aged at room temperature for at least one week prior to analysis. 1

Dynamic Mechanical Spectroscopy (DM5). Rectangular bars (3 χ 12 χ 45 mm) were cut from the molded plaques and dynamic mechanical spectra (DMS) obtained using a Rheometrics System-4. Values of G',G" and tan δ at various temperature the bars at 1 Hz and 0.2 between -100°C and 120°C at 5°C intervals in the transition regions and at 10°C intervals elsewhere. Thermal soak times were five minutes in al 1 cases. Wide Angle X-Ray Scattering. WAXS data was obtained on 25 χ 25 χ 3 mm samples; reflected intensity was recorded as a function of scattering angle (2θ ) at 1° min" , with a Siemens D500 diffractometer, using monochromated Cu-k radiation. 1

Differential Scanning Calorimetry. DSC scans were made at 20°C min" on a Mettler TA3000 system equipped with a DSC-30 low temperature module. Temperature calibration was done with a multiple indiumlead-nickel standard. An indium standard was used for heat flow calibration. Thin shavings (ca. 0.5 mm thick) were cut with a razor blade from the cross-sectional edge of a plaque. These sections contained both surface and center portions.

1

Gel Permeation Chromatography. A Waters (model 150-C ALC/GPC) liquid chromatograph with a refractive index detector was used for molecular weight characterization. The unit was equipped with two sets of silanized Dupont bimodau columns (Zorbax PSM 60S/100S), with molecu­ lar weight range 2 χ 10 to 10° and total retention volume of 24 ml. Samples were cut across the plaque thickness as with DSC. Polymer solutions were prepared in Ν,Ν'-dimethyl -formamide, DMF, at 0.1% (w/v) and f i l t e r e d through 0.45 micron nylon f i l t e r s (Rainin Instruments). Injection volume was 0.2 ml and the solvent temperature in the columns was 80°C. Flow rate was adjusted between 0.5 and 1.0 ml min" to keep the pressure at ca. 80% of the maximum pressure setting (16MPa). The data for each run was continuously fed to a PDP 11/60 computer for storage and further analysis. Calcu­ lations were done using a polystyrene standard calibration, since polyurethane calibrations are currently unavailable. z

1

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

3.

CAMARGO ET AL.

Phase Separation Studies in RIM Polyurethanes

33

Mechanical Pro per ties. Stress-strain curves for two of the series studied M-B-40/15-49 and M-E-23/25-48 were done at Rubicon Chemicals (Woodbury, NJ), using the ASTYM D-412 method (tensile properties of rubbers) at a strain rate of 500 mm min" . Young's modulus was determined from the i n i t i a l slope of the stress-strain curve of at least two to four samples. 1

Results Dynamic Mechanical Spectra. Dynamic shear moduli, G* and G" for BDO and EDO based materials are shown in Figures 2 to 4. For the 23/25 polyol, increased reaction rate (catalyst) leads to greater dependence of the storage modulus in the rubbery region. As in our previous findings,(6) overall phase separation seems to be improved by lower reaction rates. Increasing polyol molecular weight to 4000 reduces differences in the modulus temperature behavior as a function of catalyst composition (cf. Figure 3). Unlike in our earlie observed in the glass transitio T as a function of catalyst content. Similar results were obtained by DSC (as discussed later). An increase in the polyol molecular weight, on the other hand, decreased the T significantly (Figure 5). The T values obtained by DSC however? were about 10° lower than DMS data. Similar differences were found by Zdrahala et a l . (11-12) and Russo and Thomas (13). We studied two factors which affect dynamic moduli vs. temperature behavior: catalyst concentration, or equivalently, reaction speed, and polyol molecular weight. One way of comparing the data i s to look at the &{-ZlPz)IGi{llPC) ratio. This i s a measurement of the flatness of the rubbery plateau. The two temperatures are rather arbitrary but they can be taken as practical limits of use for these elastomers, at least in automotive applications. Figure 6 shows the effect of catalyst concentration on the ratio G'i-SO^CJ/G'^C) of different series. Higher catalyst content produces a polymer with more*modulus temperature sensitivity. For the sake of completeness the series M-B-20/30-6 studied earlier (6) has been added. Figure 7 shows that polyol molecular weight decreases G (-30°C)/G (70°C). We interpret this as an increase in the degree of phase separation. We would expect this trend to level off at higher molecular weight polyols. gs

qs

g

,

,

Amorphous Systems. The linear viscoelastic properties of the amorphous series (M-M-23/25-51 and 24M-B-23/25-48) are very different from the ones discussed so far in that the T ' s are ca. 30°C higher than those found in semi crystal 1i ne MDI-BD0 or MDI-ED0 based systems. In Figure 8 we compare G' and G" for samples produced under similar conditions from symmetric and asymmetric MDI isomers. The storage modulus of the 24-MDI based material drops by about three orders of magnitude after T . Above 50°C, dynamic mechanical measurements were discontinued due to extreme softening of the qs

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

REACTION INJECTION MOLDING

10* Ε

1

1

-100

1

1

1

ι

1

1

Γ

-20 20 60 100 Temperature (°C) Figure 2. Dynamic mechanical properties for the M-B-23/25-48 series as a function of catalyst concentration. %DBTDL χ 1000: · , 05; A , 30; •, 75. 10 E 4

1I -100

-60

1

1

1

ι

ι -60

ι

1

1

1

1

1

1

3

ι ι ι ι ι ι I -20 20 60 100 Temperature (°C) Figure 3. Dynamic mechanical properties for the M-B-40/15-49 series as a function of catalyst concentration. %DBTDL χ 1000: ·> 05; A , 30; •, 75.

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

Phase Separation Studies in RIM Polyurethanes

CAMARGO ET AL.

τ

1

1

1

1

1

1

τ

G'

-100

-βΟ

-20

20

60

100

Temperature (°C) Figure 4. Dynamic mechanical properties for the M-E-23/25-48 series as a function of catalyst concentration. %DBTDL χ 1000: •, 00; A , 10; · , 75.

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

36

REACTION INJECTION MOLDING

0

20 40 60 80 Cat. (DBTDL) % χ 1000

Figure 6. Modulus ratio, G'(-30 °C)/G'(70 °C) versus concentration of DBTDL catalyst, ( Δ ) M-B-20/30-60; ( ν ) M-B-23/25-28; ( O ) M-B-40/15-49; (• ) M-E-23/25-48.

Figure 7. Effect of polyol M on the modulus ratio, G'(-30 °C)/G' (70 °C), M-B series. n

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

Phase Separation Studies in RIM Polyurethanes

CAMARGO ET AL.

10";

ι

r

1—

1

ι

1

1

1—

1

!

(MPa]

G'

b

ιο

3

ιο

2

1

Ί

;

Ί

δ

Ό 10-j

1-100

τ

Γ -60

•—ι -20

1 20

1—— ι 60

1 100

Temperature (°C) Figure 8. Comparison of dynamic mechanical properties for poly­ urethanes made from symmetric and asymmetric MDI isomers. Key: · , based on 4,4'-MDI; A , based on 2,4'-MDI.

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

REACTION INJECTION M O L D I N G

38

samples. G' and G" vs. T curves for the MDEA based materials are similar to those of the 24-MDI shown in Figure 8. Wide Angle X-Ray Diffraction. Scattered intensity vs. angle WAXS curves for MDI-BDO based materials were similar to those previously reported by us (6) and other investigators (14-15) (cf. Figure 9a). Again, at low catalyst concentrations, prominent reflections are observed; as catalyst concentration increases, the intensity of the sharp reflections decreases until almost an amorphous looking pattern is observed in very fast systems (e.g. 0.075% DBTDL). The MDI-EDO materials display similar behavior. With no catalyst, there are strong crystalline reflections at 3.41, 3.88, 4.23, 4.75, 7.82 and 15.5 A (cf. Figure 9b). These d-spacings are in good agreement with those recently reported by Turner et al.(7) on similar systems. As catalyst concentration increases, most reflections are gradually weakened. However, some reflections s t i l l appear at very high catalyst concentrations (Figure 9b). The MDEA and 24-MDI based samples display WAXS intensity curves characteristic of amorphou three dimensional order in the domains. Differential Scanning Calorimetry. DSC scans for the M-B-23/25-48 series are shown in figure 10. Rt low catalyst concentrations, there are two prominent endotherms at ca. 215°C and 225°C. As catalyst content increases, a new broad endotherm appears at ca. 190°C. These endotherms are characteristic of a l l polyol systems polymerized at high catalyst concentrations and/or high mold temperatures (Figure 11). Multiple endotherms in MDI/BDO polymers have been previously reported by other investigators (e.g. ref. 4, 14, 16, 17). Overall heats of fusion are a measure of c r y s t a l l i n i t y and crystal perfection and size and were higher (24 J/g) for samples with low catalyst content. Figure 12 shows the DSC scans for the M-E-23/25-48 series are a function of DBTDL concentration. In general the multiple melting points for the MDI-EDO based hard segments are higher than the MDIBDO based materials. Dominguez (4) also reports higher melting points in RIM materials produced from EDO and uretonimine modified MDI. However, his temperatures are below ours made with pure MDI. Heats of reaction in the MDI-EDO samples were somewhat higher than those of the MDI-BDO counterparts. The heat of fusion of the uncatalyzed composition was signifi-cantly higher than that of the catalyzed samples (40 J/g versus 25 J/g). Molecular Weight Determination. As mentioned earlier, the GPC results for our samples are based on a polystyrene calibration curve. As such, a l l numbers must be regarded on a rel ati v^ basis. PS based weight average molecular weights, M , were about 10^ for highly reacted samples. Actual M values may be lower even by a factor of 2, based on calculations for an stepwise polycondensation with 99% conversion (18). M versus DBTDL concentrations for a typical series are shown i n T ï g u r e 13. As observed the effect of a hotter mold wall w

w

w

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

\. C A M A R G O ET AL.

Phase Separation Studies in RIM Polyurethanes

Scattering Angle, 2 Θ (degrees)

Figure 9. WAXS diffraction curves for the a) M-B-23/25-48 series and b) M-E-23/25-48 series at different levels of catalyst (DHTDL)

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

REACTION INJECTION MOLDING

1

60

t

I

ι

I

100

ι

1

ι

I

ι

I

ι

I

ι

I

140 180 Temperature (°C)

ι

I

•

220

I

ι

ι

260

Figure 10. DSC curves for the M-B-23/25-48 series at different concentrations of DBTDL catalyst.

ι . ι . ι . ι , ι . ι . ι . ι . 60

100

140 180 Temperature ( C)

220

1 260

e

Figure 11. DSC curves for different polyurethanes at 0.075% DBTDL (fast systems). Effect of the polyol M in M-B series. R

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

3. CAMARGO ET AL.

Phase Separation Studies in RIM Polyurethanes

I ι I ι 1ι I ι I ι I ι I ι I ι I ι I ι I ι I 50

90

130

170

Temperature

210

250

( C) e

Figure 12. DSC curves for the M-E-23/25-48 series at different concentrations of DBTDL catalyst. 130 O T

w

»

140 C e

•

T*=120°C —

Ô

—

—

55 - Δ / 1 0

1 20

1

I 40

1

1 60

ι

ι 80

1 100

CATALYST (DBTDL) CONC. (goat'Opo! 1 0 ) Χ

5

Figure 13. Molecular weight, Μ , versus catalyst content for the M-B-23/25-48 series. Unless otrlerwise noted, mold temperature was 70 °C.

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

42

REACTION INJECTION M O L D I N G

at constant catalyst composites is to increase the molecular weight of the sample. Figure 14 compares the different series, with M's normalized by the highest value in the series. Except for the M-B20/30-60 series in which the mold temperature was 100°C a l l other samples were molded at 70°C. A l l samples show a sharp decrease in M at 0.02-0.03% DBTDL. Judging from the results of the M-B-20/30-60 series, an increase in mold temperature allows for larger decreases in catalyst composition without major effect on the molecular weight. Information l i k e this is valuable in establishing optimum levels of catalyst or molding conditions. The M of the amorphous samples were generally high (i.e. around 10 ). It is important to note that these results hold even for the uncatalyzed sample of the M-M-23/25-51 series. In terms of reaction speed this sample is comparable to EDO or BDO based materials with ca. 0.01-0.02% DBTDL, probably due to the presence of the catalytical ly active tertiaryamine group in the MDEA molecule (10). Nonetheless, the molecular weight is comparable to that of much faster samples. This, a absence of phase segrega- tion during the reaction in the MDEA based materials. A final and important observation must be made concerning molecular weight results. Ideally the polydispersity (M /M ) of these samples should be close to 2.0. Indeed this was found in most samples with two remarkable exceptions. A decrease of catalyst content in the M-B-40/15-49 and M-E-23/25-48 series lead to higher polydispersity values. The uncatalyzed sample of the M-E-23/25-48 series for instance had a polydispersity of 8.0. Moreover, the GPC traces in these materials indicated the presence of shoulders. Upon close examination, at least one of the shoulders could be assigned to the polyol originally used in the composition, as seen in Figure 15 for the M-E-23/25-48-70-00 sample. Similar results were observed for the M-B-40/15-49-70-05 sample. Examples of high polydispersity ratios and bimodal distributions have been previously rationalized by heterogeneous reaction conditions. T i r r e l l et al .(19) found M /M values well over 2.0 and low molecular weight shoulders in slow, low temperature RIM polymerized urethanes based on polycaprolactone diols. Xu et a l . (20) have recently performed selective extraction experiments on urethanes based on toluene diisocyanate, TDI, and hydroxy1 terminated polybutadiene. They have shown that two different chain length distributions are a consequence of insoluble i n i t i a l components. w

w

b

w

w

n

n

Tensile Properties. Stress-strain data for the M-E-23/25-48 series is shown in Figure 16. Elongations at break drop rapidly with lower DBTDL concentrations. Young's modulus was measured at about 42 MPa (6,000 psi). Similar results were obtained in samples of the M-B40/15-49 series where Young's modulus in this case was ca. 60MPa (8,700 p s i ) . It is important to compare these results to molecular weight data presented in the previous section. A drop in molecular weight

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

3. CAMARGO ET AL.

o.o

43

Phase Separation Studies in RIM Polyurethanes

ι

1

1

0

10

20

ι

ι

ι

ι

30 40 50 60 Catalyst (DBTDL) % χ 1000

ι

I

70

80

Figure 14. Normalized molecular weights versus catalyst concen­ tration for different series. M ref. = value at highest catalyst. Key: Δ , M-B-20/30-60-100; Ο, M-B-23/25-48; M-B-40/15-49; V, M-E-23/25-48. w

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

44

REACTION INJECTION MOLDING

Solvent: OMF

I

Flow rate: 0.5 ml/min

I

12.5

15.0 17.5 Elution Volume (ml)

20.0

22.5

Figure 15. GPC traces for catalyzed (M-E-23/25-48-70-75) and uncata­ lyzed (M-E-23/25-48-70-00) RIM samples and the starting polyol, 23/25. Note the correspondence between the shoulder in the uncata­ lyzed sample and the polyol.

0 I 0

ι 100

ι

ι

200 300 Elongation (%)

I

—Lo

400

500

Figure 16. Stress-strain curves for the M-E-23/25-48 series as a function of catalyst concentration.

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

3. CAMARGO ET AL.

45

Phase Separation Studies in RIM Polyurethanes

of ca. 20% represent changes in elongation from 500% to 100%. Only those samples with 0.075% DBTDL display stress-strain data typical of elastomeric materials. Evidently in linear polyurethanes produced by RIM, only with high catalyst levels are molecular weights in the region where mechanical properties became insensitive to molecular weight [21). This characteristic certainly justifies the use of t r i o l s or multifunctional isocyanates in commercial RIM systems, provided that morphology and domain formation are not significantly affected. Discussions Crystalline Systems. Lower T , f l a t t e r rubbery plateau modulus, higher hard segment c r y s t a l l i n i t y , a l l support the view that phase separation is more complete MDI-BDO and MDI-EDO based polyurethanes as catalyst concentration decreases. Highly catalyzed materials display a temperature sensitive plateau modulus and lowe WAXS and DSC data. Thes tensile properties. Recent FTIR data indicates that there is a high degree of hard segment association through hydrogen bonding (10,22). The evidence suggests that rapidly polymerized specimens can be viewed as a disperse, highly interconnected network of loosely organized hard segments reinforcing a polyether rich soft segment matrix. Additional arguments to support this hypothesis follow. Hashimoto and coworkers (23) analyzed the effects of interdomain mixing and phase boundary mixing (i.e. broader interphases) on the linear viscoelastic properties of block copolymers. Briefly, both mixing and interphase broadening increase the temperature dependence of the storage modulus. Changes on the loss modulus, however, are different in the two cases. Interdomain mixing results in shifts of the transition peaks toward each other with l i t t l e or no broadening. Interphase boundary mixing, on the other hand, produces a broadening of the transition peaks but negligible shifts of the transition temperatures. Based on the above interpretation, the main effect of increased catalyst concentration is to produce more diffuse boundaries between the hard and the soft domains, since differences in T . among the samples are small, while differences in temperature dependency of the modulus are large as indicated by Figure 6. It is interesting to observe in this figure also that a l l curves converge to a limiting modulus ratio value of about 3.0, G (-30°C)/G (70°C). A survey of literature data (5,12,24) indicates that for polyether urethane elastomers of similar hard segment concentration, the modulus ratio values are greater or equal to this limiting value. It is therefore reasonable to assume that 3.0 corresponds to a system that is completely phase separated with very sharp boundaries. In very slow systems this situation is accomplished by an early precipitation of mobile hard segment oligomers which form reasonably stable crystalline structures. However, there is a low degree of connectivity between hard and soft segments because the tight packing gs

gs

,

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

,

46

REACTION INJECTION M O L D I N G

of the crystalline structures prevents further reaction of groups attached to crystalline chains. As the reaction speed increases, high conversions can be achieved in a time interval shorter than the characteristic time for phase separation. Moreover, nonisothermal effects become important. Due to the exothermic nature of the reaction, the temperature of the reactive medium is greatly increased possibly to the region of phase compatibi 1 ization. At this point the system can cool down, but domain formation is d i f f i c u l t due to high molecular weight and high viscosity. Thus only a finely interconnected structure results. Reduced segment mobility prevents the hard segments from reaching a high degree of crystalline organization. Increasing the molecular weight of the polyol decreases the c r i t i c a l value of the interaction parameter x for phase separation and thus increases the driving force for phase separation. Hence the f l a t t e r modulus plateau in the samples of the M-B-40/15-48 series. Another variable that may also contribute to the higher degree of phase separation in the M-B-40/15-4 oxide content of the polyo segment is more polar than the polypropylene oxide ones, we expect ethylene oxide to promote phase mixing. Recently, Kojima and coworkers (24) have shown that the temperature dependence of modulus in RIM uretHânes increases as the content of ethylene oxide in a t r i o l of constant equivalent weight increases. The picture presented thus far is also supported by other experimental data. WAXS and DSC data show that rapidly polymerized samples do not display a high degree of crytal u n i t y in the hard segments. Annealing studies of some of our samples indicate that the broad peak at ca. 190°C can be slowly converted to a peak at ca. 220°C. If annealing is done at high enough temperature (210°C or higher), a new DSC endotherm appears ca. 235°C(10). This is in agreement with recent work of Thomas and Briber~T25) and Blackwell and Lee (26) who have independently proposed the existence of at least two different crystal structures in MDI/BDO based hard segments. Perhaps one of the most important effects of a low reaction rate and premature phase separation is the decrease in molecular weight of the material. This clearly must be avoided as i t seriously decreases the tensile properties of the polymer. There exists therefore a balance between the degree of phase separation and organization that can be achieved and the maximum molecular weight. As the latter has more importance regarding the performance of the material, i t is necessary in real systems to turn to other alternatives such as the use of t r i o l s or graft polyol s to increase molecular weight without seriously affecting the a b i l i t y of the system to reach a certain degree of phase separation. F i n a l l y , a word must be said regarding spacial variations. In real samples, large temperature gradients develop during the polymerization. Generally monomers near the mold w a l l , react slower, and thus can undergo phase separation at an early stage, decreasing the local molecular weight of the material. Center to surface A B

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

3.

47

Phase Separation Studies in RIM Polyurethanes

CAMARGO ET AL.

variation tend to be magnified at intermediate catalyst concentrations (e.g. 0.01 to 0.05% DBTDL). At concentrations lower than these, the overall system is slow and early phase separation occurs throughout the part. At very high catalyst concentrations, the reaction is fast even near the mold w a l l . High conversions can be reached before appreciable phase separation can affect molecular weight. For this reason, surface to center differences are also minimized (cf. r é f . 6, Figure 5). Non-crystal 1 ine Systems. As inferred from the experimental data, those systems based on 24-MDI or MDEA are highly compatible and have a low modulus at room temperature. They only display a single T much higher than the one of the crystalline systems described in the previous section. It i s useful to compare the T values obtained for the amorphous M-M-23/25-51 and 24-M-B-23/25-48 series to predictions for random homo-geneous systems. Using for instance Fox's equation (27): g

a

1 _ s , h τ - τ τ 'g 'gs gh w

+

where w and w^ are the weight fractions of the soft (s) and hard (h) phases and T and T are the corresponding glass transition temperatures? T for the polyethers used in this work i s -65°C (10). Hwang et a l . (28) reported Τ = 54°C for the MDI/MDEA hard segment. T for the~?4-MDI/BD0 hard segments has been measured at 74°C using a copolymer polymerized in solution (10). As observed from Table III, the predictions of Fox's equation are in good agree­ ment with the values measured in this work, indicating once again that these systems are highly compatible. Summarizing then, the amorphous glycol extended systems have a large degree of phase compatibility and poorly defined elastomeric behavior. The absence of c r y s t a l l i n i t y reduces the driving force available for phase separation. This i s necessary to overcome speci­ f i c hard-soft segment interactions such as hydrogen bonding that tends to reduce the interaction parameter between the blocks. Crystallinity i s not the only mechanism available to increase x . Other specific intradomain interactions such as π-electron attractive forces can also help phase development without c r y s t a l l i n i t y as shown by Camberlin et a l . (29). In polyurethaneurea systems, a strong hydrogen bonding (mostTikely a 3-D arrangement) can explain the phase separation and excellent properties of these polymers without c r y s t a l l i n i t y . The absence of intersegmented interactions can make an otherwise compatible system become more phase separated. These have been well illustrated by the work of Cooper et a l . (30) who have prepared MDI/MDEA based systems using polytetramethyTëne oxide and polybutadiene based soft segments. Since with PBD soft segments there i s no possibility of hard-soft segment hydrogen bonding, these materials show a more complete phase separation than in the ΡΤΜ0 materials. s

gs

gh

as

h

gh

A B

American Chemical Society Library 1155 tetk st N. w.

WtthtagtM, C 20038 In Reaction Injection0. Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

-22

24M-B-23/25-48-70-150

(1) (2) (3)

-12

Μ-Μ-23/25-51-70-Ί9

From dynamic mechanical spectra From differential scanning calorimetry Predicted from Fox equation (see text)

-23.5

-18.6

21

V" V g

(3)

-15.6

-18.7

T

832

794

G'(-30°) MPa

>100

>100

G'(-30 °C) G'( 70 °C)

DMA and DSC Data for Glycol Extended Amorphous Samples

SAMPLE

Table III.

3.

CAMARGO ET AL.

Phase Separation Studies in RIM Polyurethanes

49

Summary and Conclusions Through this work we have demonstrated the following points concern­ ing phase separation and properties in bulk RIM polymerized polyurethane elastomers: •The final degree of phase separation, and the molecular weight, in semi-crystal 1ine systems are highly dependent on the rate of polymerization, controlled mainly by the catalyst concentration. • Low reaction rates favor the crystallization of oligomeric materials during the polymerization. Although the samples show a high degree of phase separation and hard segment c r y s t a l l i n i t y , the hetero-geneous conditions of the reaction decrease the molecular weight, resulting in a b r i t t l e material with poor tensile properties. •At high reaction rates most of the polymerization takes place before phase separation. The final degree of phase separation and hard segment organization depend mostly on the molding conditions and thermal history of the material. Under normal RIM conditions the system can be regarded a segments dispersed throughout a polyether rich hard segment matrix. This high dispersion of poorly organized hard segments yields a high temperature dependence of the storage modulus. • Increasing the polyol molecular weight increases the length of the segments and increases phase incompatibility. At high enough polyether molecular weight, the effect of catalyst concentration on the temperature dependence of the modulus becomes less apparent. • Comparison between ethanediol and butanediol extenders i n d i ­ cates that the former produces hard segment crystals with a higher melting temperature. Because of higher urethane group concentration in the ethanediol based hard segments, these tend to have higher cohesion thus giving higher T . The use of monomers that produce amorphous hard segments pro­ duces highly compatible systems with poorly defined rubbery plateau and elastomeric behavior. Because no heterogenous conditions develop during the reaction, molecular weight in amorphous polyurethane systems tends to be less affected by reaction rates or polymerization conditions. Hard segment crystal 1izabi1ity, and/or other specific interac­ tions such as π-electron forces between aromatic groups or 3-D hydrogen bonding provide higher cohesive intersegmental forces. m

Acknowledgments This work was supported by cooperative funding from the National Science Foundation, Grant NSF-CPE-8118-232, the General Motors Corporation and the Union Carbide Corporation. The authors are also indebted to Drs. D. Spence and J . Ferrari ni from Rubicon Chemicals, R. Lloyd from Texaco Chemicals, J . O'Connors from 01 in Park and R. Gerkin and L. Lawler from Union Carbide for providing us with the raw

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

50

REACTION INJECTION MOLDING

chemicals used in this work. Invaluable assistance by K. Dulin, J . Horns and J . Andrews in sample preparation and characterization is acknowledged. One of the authors (R.E.C.) would also l i k e to thank the 3M Company for fellowship support through this project.

Literature Cited 1.

R.M. Gerkin and F. E. Critchfield, Paper 741022, Soc. Automo­ tive Engineers Mtg. Toronto, Canada, Oct., 1974. 2. I.D. Fridman, E.L. Thomas, L.J. Lee and C.W. Macosko, Polymer 21, 393 (1980). 3. D.M. Rice and R.J.G. Dominguez, Polym. Eng. Sci., 20, 1192 (1980). 4. R.J.G. Dominguez, Polym. Eng. Sci., 21, 1210 (1981). 5. R.B. Turner, H.L. Spell and J.A. Vanderhider, in "Reaction Injection Molding and Fast Polymerization Reactions," J.E. Kresta, Ed., p. 63, Plenum Press, N.Y., 1982. 6. R.E. Camargo, C.W Macosko M Tirrell d S.T Wellinghoff ibid., p. 95; Polym 7. J. Blackwell, J. Quay, and R.B. Turner, Polym. Eng. Sci., 23, 816 (1983). 8. P. Kolodziej, C.W. Macosko, and W.E. Ranz, Polym. Eng. Sci., 22, 388 (1982). 9. L.J. Lee, and C.W. Macosko, S.P.E. ANTEC Tech. Papers, 24, 151 (1978); U.S. Patent 4,189,070 (1979). 10. R.E. Camargo, Ph.D. Thesis, Dept. of Chemical Engineering and Mat. Sci., U. of Minnesota, 1983. 11. R.J. Zdrahala, R.M. Gerkin, S.L. Hager and F.E. Critchfield, J. Appl. Polym. Sci., 24, 2041 (1979). 12. R.J. Zdrahala, S.L. Hager, R.M. Gerkin and F.E. Critchfield, J. Elastom. Plast., 12, 225 (1980). 13. R. Russo and E.L. Thomas, J. Macromol. Sci., Phys., B22, 553 (1983). 14. A.L. Chang, R.M. Briber, E.L. Thomas, R.J. Zdrahala, and F.E. Critchfield, Polymer, 23, 1060 (1982). 15. N.S. Schneider, C.R. Desper, J.R. Illinger, and A.O. King, J. Macromol. Sci., Phys., B11, 527 (1975). 16. R.W. Seymour, and S.L. Cooper, Macromolecules, 6, 48 (1973). 17. T.R. Hesketh, J.W.C. Van Bogart, and S.L. Cooper, Polym. Eng. Sci., 20, 190 (1980). 18. F. Lopez-Serrano, J.M. Castro, C.W. Macosko and M. Tirrell, Polymer, 21, 263 (1980). 19. M. T i r r e l l , L.J. Lee, and C.W. Macosko, A.C.S. Symp. Series, 104, 149 (1979). 20. M. Xu, W.J. MacKnight, C.H.Y. Chen and E.L. Thomas, Polymer, 24, 1327 (1983). 21. J.H. Saunders, Rubber Chem. Technol., 33, 1259 (1960). 22. F.M. Mirabella, Northern Petrochemical Co., Personnal Comm., 1983. 23. T. Hashimoto, Y. Tsukahara, K. Tachi, and H. Kawai, Macromolecules, 16, 648 (1983).

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

3. C A M A R G O ET AL.

Phase Separation Studies in RIM Polyurethanes

51

24. H. Kojima, H. Nishimura and M. Funaki, Reports of the Research Lab. Asahi Glass Co., 31, 109 (1981). 25. R.M. Briber and E.L. Thomas, J. Macromol. Sci., Phys., B22, 509 (1983). 26. J. Blackwell and C.D. Lee, submitted for publication, 1983. 27. F.W. Billmeyer, "Principles of Polymer Science," 2d. ed., Wiley, 1984. 28. K.K.S. Hwang, C.Z. Yang and S.L. Cooper, Polym. Eng. Sci., 21, 1027 (1981). 29. Y. Camberlin, P. Pascault, M. Letoffe, and P. Claudy, J. Polym. Sci., Polym. Chem. Ed., 20, 1445 (1982). 30. C.Z. Yang, K.K.S. Hwang and S.L. Cooper, Macromol., to appear. RECEIVED October 5, 1984

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

4 Investigations of the Structure-Property Relationships for RIM Polyurethane Elastomers Effect of an Amine Additive 1

1

ROBERT B. TURNER , CHRISTINE E. MACDONALD , J O H N J E F F R E Y R. QUAY , and C H U N DONG L E E 2

2

BLACKWELL ,

2

1

The Dow Chemical Company, Freeport, TX 77541 Department of Macromolecular Science, Case Western Reserve University, Cleveland, OH 44106

2

Structural an for RIM polyurethane modified diphenylmethane 4,4'-diisocyanate (MDI), ethylene glycol (EG), and a polypropylene oxide soft segment polyol (Mn 5000), with and without the addition of a polyether diamine (PEDA). A series of specimens containing 18 parts and 30 parts EG (per 100 parts by weight of polyol) were prepared with and without the addition of a PEDA, and were examined before and after thermal annealing (120°C for 1 hour). X-ray analyses show that the hard domain cystallite size and degree of crystallinity is increased by thermal annealing in the specimens prepared without PEDA. Significantly, the same structural improvement is achieved by use of the PEDA additive without the annealing step. These results are seen to correlate with the thermal and mechanical data, and show that the improvement in heat sag behavior can be effected by use of the PEDA additive without annealing. It is suggested that the mechanism for this improvement may involve MDI-capped PEDA as a nucleation site for the hard domains. At present there i s considerable interest i n the structure and pro­ perties of reaction injected molded (RIM) polyurethanes elastomers for many applications, including automobile bodies. Polyurethane elastomers are multiblock copolymers comprised of alternating polyurethane and polyether or polyester segments. At use tem­ peratures the polyurethane and polyol segments are respectively below and above t h e i r glass t r a n s i t i o n temperatures, and are designated hard and soft segments. The elastomeric properties are derived from phase separation, such that the polyurethane segments form hard domains within the soft segment matrix. These hard domains serve as physical cross-links and reinforcing f i l l e r par­ t i c l e s [1-4]· A wide range of properties i s possible, depending on the hard/soft r a t i o and the selected chemical structure. 0097-^156/ 85/0270-Ό053$06.00/0 © 1985 American Chemical Society

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

54

REACTION INJECTION M O L D I N G

In t h i s paper we describe investigation of the structure and propert i e s of RIM polyurethane elastomers prepared from dipheny1-4,4 diisocyanate (MDI) with ethylene g l y c o l (EG) as the hard segment chain extender and copoly(ethylene oxide/propylene oxide) as the soft segment. The softening point of these polyurethanes i s f r e quently i n the range 80 - 100°C, but i s found to increase as a result of thermal annealing [5-6]. Greater improvement i n the thermal properties, and also i n the mechanical properties such as impact strength, f l e x u r a l modulus, and heat sag, can be achieved by addit i o n of organic diamines to the polyol/chain extender [5-7]. We are investigating the physical structure of these RIM polyurethanes i n order to understand the effect of the diamine additives on the prop e r t i e s . A preliminary account of this work has been published previously [8]. 1

Poly (MDI/EG) hard segments can c r y s t a l l i z e , and the development of c r y s t a l l i n i t y i s thought to be part of the driving force for phase separation. The X-ray d i f f r a c t i o polyurethanes are now wel Figure 1 shows the X-ray pattern of an oriented f i l m of a polyurethane elastomer prepared using MDI and EG. The hard/soft r a t i o i s approximately 50/50, and the specimen had been stretched 720% and annealed f o r 14 days at 130 degrees C. The soft segments are amorphous and a l l the Bragg r e f l e c t i o n s arise from the c r y s t a l l i n e hard domains. Of p a r t i c u l a r interest are the sharp meridional r e f l e c t i o n s at d * 15.0 and 7. which are indexed 001 and 002, respectively, and a r i s e from planes perpendicular to the chain axis ( i . e . the d i r e c t i o n of draw) [9-10]· These r e f l e c t i o n s have been used [11] to estimate the c r y s t a l l i t e thickness along the chain axis and also the extent of paracrystalline d i s t o r t i o n as functions of elongation and annealing. I t was found that noncross linked polyurethanes prepared using EG as the hard segment showed a small but s i g n i f i c a n t increase i n a x i a l c r y s t a l l i t e width (from 75 to 85A i n the present example) as a result of elongation and annealing, and these results point to a hard domain structure formed by l a t e r a l aggregation of p a r a l l e l hard segments. These meridional r e f l e c t i o n s are e a s i l y i d e n t i f i e d i n less c r y s t a l l i n e unoriented specimens, because they are well away from the amorphous halo (6 -4A), and hence t h e i r i n t e n s i t i e s can be used to compare the r e l a t i v e c r y s t a l l i n i t y of specimens produced by d i f f e r e n t processing techniques. We have used X-ray methods to compare the c r y s t a l l i t e size of RIM specimens prepared with and without use of a polyether diamine (PEDA) additive. These results are compared with d i f f e r e n t i a l scanning calorimetry data on the hard domain melting behavior and dynamic-mechanical studies of the extent of phase separation. Mechanical data on f l e x u r a l modulus, elongation, impact strength, and heat sag behavior have been obtained for the same specimens and have been correlated with the s t r u c t u r a l analyses.

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

4.

T U R N E R ET A L .

RIM Polyurethane Elastomers: Amine Additive Effects

Figure 1. X-ray pattern of an oriented f i l m of a polyurethane elastomer.

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

55

56

REACTION INJECTION M O L D I N G

Experimental Specimen Preparation. These polymers were polymerized using a Krauss-Maffei PU 80/40 RIM (reaction i n j e c t i o n molding) machine using a suitable catalyst (Witco Fomrez UL-28). 6" χ 6" χ 1/8" p l a ­ ques were produced i n a P20 s t e e l mold heated to 160°F (71°C). The MDI was Upjohn s Isonate 143L, which i s diphenylmethane 4,4'-isocyanate modified with 15% uretonimine. Ethylene g l y c o l (EG) was used as the chain extender and the soft segment was a polyether t r i o l with a molecular weight (Mn) of 5000 prepared from propylene oxide and capped with ethylene oxide. The polyether diamine (PEDA) i s an amine-terminated poly(propylene oxide). Two sets of specimens were prepared containing 18 and 30 parts EG per 100 parts by weight of polyether t r i o l at a 105 isocyanate index. These w i l l be referred to as the 18 EG and 30 EG s e r i e s , and contain approximately 43% and 64% hard segments. Diamine modified specimens were prepared by the addition of PEDA to the 18 or 30 parts EG systems. In view of the difference i n molecula r e s u l t s i n only a smal i n the hard segment content. The specimens were examined i n the as prepared state and a f t e r annealing f o r 1 hour at 120 degrees C. 1

X-Ray D i f f r a c t i o n . Data were obtained as 2 θ scans of the s t a ­ tionary specimens i n the transmission mode using N i - f i l t e r e d CuK r a d i a t i o n and a Schintag Pad I I computer controlled d i f f T a c t o m e t e r . Intensity measurements were made from 2 0 4.0 degrees to 32.0 degrees using 0.2 degree steps and 60 second counting times. A x i a l c r y s t a l l i t e sizes were derived from the 001 i n t e g r a l breadths, following correction f o r instrumental broadening. s

Heat Sag. One inch wide and 1/8" thick s t r i p s were supported h o r i ­ zontally with a 4" overhang and were placed i n an oven at 120 C, and the v e r t i c a l drop of the end a f t e r 1 hour was recorded according to ASTM D3769-79. Mechanical Testing. Impact strength was measured using ASTM method D-250-56 and i s reported i n foot-pound per inch of notch. Elongation and f l e x u r a l modulus were measured on an Instron tester model number 1125 according to ASTM D-638 and ASTM D-790 tests respectively. D i f f e r e n t i a l Scanning Calorimetry. Specimens were heated at a rate of 20 degrees/minute using a Perkin-Elmer DSC-2C. A l l samples were normalized for sample weight and tested under a nitrogen atmosphere. Dynamic Mechanical Spectroscopy. Samples were run i n the t e n s i l e mode using a Rheometrics Model 605 Mechanical Spectrometer. Temperature scans were run from -160 to 240 C using a s t r a i n of 0.15% and a frequency of 1 Hertz. Samples were maintained i n a nitrogen atmosphere during t e s t i n g .

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

4. T U R N E R ET AL.

RIM Polyurethane Elastomers: Amine Additive Effects

57

Results and Discussion. X-ray d i f f r a c t i o n densitometer scans are presented i n Figures 2 f o r the 18 EG and Figure 3 f o r the 30 EG series for RIM polyurethanes. DSC and Storage Modulus traces (EI) for the same specimens are shown i n Figures 4, 5 and 6, and f l e x u r a l modulus, elongation, impact strength, and heat sag data are given i n Table I . The densitometer scans of a l l the specimens show peaks at 15.0 and 7.5A that demonstrate the presence of c r y s t a l l i n e hard segments. These peaks are poorly resolved f o r the unannealed/wlthout PEDA spe­ cimens but increase i n i n t e n s i t y on annealing. S i g n i f i c a n t l y , the unannealed/with PEDA specimens give d i f f r a c t i o n patterns that are s i m i l a r to those f o r the annealed/without PEDA specimens, and e s t i ­ mates of the peak areas indicate an approximate doubling of the c r y s t a l l i n i t y . Very l i t t l e further improvement i s obtained when the samples added with PEDA are annealed. Not s u r p r i s i n g l y , the 30 EG series of specimens are more c r y s t a l l i n e than the 18 EG s e r i e s , which have a lower har the absolute degree of than i n the oriented annealed specimen of the noncrosslinked polyurethane (Figure 1), for which the 15.0 and 7. reflections have much higher r e l a t i v e i n t e n s i t y . The lower c r y s t a l l i n i t y of the RIM specimens i s to be expected because of the crosslinking that occurs as a result of the use of t r l f u n c t i o n a l soft segments. We are currently developing methods to determine the absolute hard segment c r y s t a l l i n i t i e s from data of t h i s type. C r y s t a l l i t e sizes determined f o r both series of specimens using the Scherrer equation and the i n t e g r a l breadth of the 15.θ£ peak are given i n T a b l e I I . The figure f o r the unannealed/without PEDA specimens must be viewed as very approximate given the quality of the data. Nevertheless, there i s an increase i n the c r y s t a l l i t e size on annealing without PEDA specimens, from 54 to 76A for 18 EG and from 61 to 75A for 30 EG. The same increase i s seen as a r e s u l t of the use of the PEDA additive, and there i s l i t t l e further change on annealing. These widths are less than those seen i n equivalent l i n e a r polyurethanes [10], and t h i s i s probably due to the effects of the crosslinking which i n h i b i t s organization of the hard domains. Figure 4 and 5 and Table I I I show the DSC data for these RIM s p e c i ­ mens. I t i s seen t h a t A H f o r the hard segment melting i n the unannealed/without PEDA specimens increases on annealing ( f o r both the 18 Eg and 30 Eg series) and e s s e n t i a l l y the same increase occurs i n the unannealed/with PEDA specimens. These effects corrleate with the X-ray data showing a similar increase i n the c r y s t a l l i n e perfec­ t i o n of the hard domains with annealing or with the use of PEDA. The decrease i n the melting temperature f o r the hard domain prepared with PEDA suggests that the PEDA i s naturally associated with the hard segments, probably at the boundaries of the hard domains. I t should also be noted that the use of PEDA reduces the average hard segment length, and t h i s may also be a factor leading to the lower melting points of the PEDA specimens.

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

58

REACTION INJECTION MOLDING

Figure 2.

X-ray d i f f r a c t i o n densitometer scans, 18 EG s e r i e s .

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

4.

RIM Polyurethane Elastomers: Amine Additive Effects

URNER ET AL.

—ι

0.1

1

0.2

1

TAN

Figure 3.

1

0.3

0.4

r~

0.5

20

X-ray d i f f r a c t i o n densitometer scans, 30 EG s e r i e s .

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

59

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

(psi)

(in)

after

120°C

after

(in)

120°C

at

a

Izod

MP

60 m i n

Strength,

Heat-sag

Impact

(%)

I Z O D Nm/m

notch)

(psi)

60 m i n .

modulus

Elongation

Flexural

18 E G S e r i e s

at

Heat-sag

of

Strength,

(%)

(ft-lbs/in

Impact

Elongation

No

134

287

0.7

break

188

(19,500)

0.3

(5.3)

122

(60,000)

413

a

Flexural

Modulus

Unannealed

MP

Property

Diamine

I:

30 EG S e r i e s

No

Table

124

314

400

No

RIM

Diamine

For

0.5

break

255

(18,000)

0.2

(5.8)

172

No

214

650

617

0.4

break

150

(31,000)

0.2

(12.0)

100

(89,500)

Unnanealed

PEDA

Polyurethanes

(58,000)

Annealed

No

Data

PEDA

No

207

705

599

0.5

break

260

(30,000)

0.1

(13.0)

214

(87,000)

Annealed

RIM Polyurethane Elastomers: Amine Additive Effects

4. TURNER ET AL.

Table I I - A x i a l C r y s t a l l i t e Widths

SAMPLE DESCRIPTION

CRYSTALLITE SIZE

18 EG, Unannealed

54

18 EG, Annealed

76

18 EG, 7.5 PEDA, Unannealed

72

30 EG, Unanneale

30 EG, Annealed

75

30 EG, 7.5 PEDA, Unannealed

76

Table I I I . Melt Temperatures and Heats of Fusion

SAMPLE DESCRIPTION

Τ MELT (°C)

Δ ϋ ί (CAL/g)

18 EG, Unannealed

229.4

17.1

18 EG, Annealed

228.5

24.8

18 EG, 7.5 PEDA, Unannealed

218.1

24.9

30 EG, Unannealed

228.7

24.3

30 EG, Annealed

229.2

36.2

30 EG, 7.5 PEDA, Unannealed

224.8

38.7

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

61

REACTION INJECTION M O L D I N G

PEDA ANNEALED PEDA UNANNEALED ANNEALED UNANNEALED

PEDA ANNEALED PEDA UNANNEALED ANNEALED UNANNEALED 150

170

190

210

TEMPERATURE Figure 5.

DSC

230

250

( C)

scans, 30 EG

series.

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

4. TURNER ET AL.

RIM Polyurethane Elastomers: Amine Additive Effects

The dynamic mechanical data (Figure 6) point to enhanced phase separation as a result of annealing, as shown by the f l a t t e r storage modulus curves. The data show that a similar improvement i s obtained by annealing without PEDA and by addition of PEDA without annealing. A similar conclusion i s also derived from the heat sag data. Thus the s t r u c t u r a l and mechanical data are mutually compatible and point to an increase i n the order of the hard domains as a result of use of the PEDA additive, comparable to that which i s achieved by annealing without use of the additive. At present we can only spe­ culate on the mechanism whereby the PEDA leads to the higher order. The c r y s t a l l i n e r e f l e c t i o n s are those of homopoly (MDI/EG) and hence the PEDA chains must be outside the c r y s t a l l i n e regions, but the f l e x u r a l modulus does increase indicating some hard domain asso­ c i a t i o n . Nevertheless, the PEDA could be intimately involved with the hard domains. The amine groups are much more reative than the hydroxyls of the chain extende mical reaction w i l l involv may serve as nucleation agents f o r the formation of the hard domains, perhaps because of their low s o l u b i l i t y i n the reaction mixture.

10* r -150

1

1

-100

-50

1

0

»

1

50

100

ι

150

TEMPERATURE ( ° C ) Figure 6.

DMS scans.

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

63

REACTION INJECTION M O L D I N G

64 Acknowledgments

The r e s e a r c h at Case Western Reserve U n i v e r s i t y was s u p p o r t e d by a g r a n t from the Dow Chemical Company.

Literature Cited 1. 2.

S. L. Cooper and V. Tobolsky, J . of Appl. Polym. Sci. 10 (1966). D. C. Allport and A. A. Mohagu, in "Block Copolymers" (ed. D. C. Allport) Wiley-Interscience, New York, 1973. 3. A. Noshay and J . E. McGrath, "Block Copolymers—Overview and C r i t i c a l Survey," Academic Press, 1977. 4. T. L. Smith, Polm. Eng. Sci. 17, 129 (1977). 5. M. C. Cornell, R. B. Turner, and R. E. Morgan, "Amine Modified Polyol for RIM Systems," 26th Ann. Tec. Conf., SPI, Polyurethane Div., 1981. 6. R. Dominquez, "The Effect of Annealing on the Thermal Properties of RIM Urethane Elastomers, Fast Reaction System 1982. 7. J . A. Vanderhider and G. M. Lancaster, U.S. Patent 4,269,945 (1981). 8. J . Blackwell, J . R. Quay, and R. B. Turner, manuscript submitted to Polymer Science and Engineering. 9. J . Blackwell, M. R. Nagarajan, and T. B. Hoitink, Polymer 22, 1534 (1981). 10. J . Blackwell, M. R. Nagarajan, and T. B. Hoitink, Polymer 23, 950 (1982). 11. J . Blackwell and C. D. Lee, J . Polymer S c i . , Polymer Phys. Edns., in press. RECEIVED

October 5,

1984

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

5 Effect of Urethane RIM Morphology on Deviation from Second-Order, Straight-Line Dependence 1

A. DAMUSIS and T. B. LIN Polymer Institute, University of Detroit, Detroit,MI48221

Conversion levels of polymerization at the deviation points from straigh order reaction graph tents of rigid segments and of plasticizer in the ure­ thane RIM formulations. Experimental data of exother­ mic temperature and of conversion levels versus reaction time were obtained in an adiabatic reactor and were programmed by a regression method using a compu­ ter. Formation of fringed micelle crystallites in the process of urethane RIM polymerization was a factor influencing deviation from the straight line dependence of regular kinetics. The crystalline aggregates were evaluated by the permanent set values and at three levels of temperature by the stress relaxation method.

I n some cases RIM r e a c t i o n k i n e t i c d a t a i n d i c a t e d the d e v i a t i o n s from the s t r a i g h t l i n e dependence o f the second o r d e r r e a c t i o n e q u a t i o n plots. Some a g g l o m e r a t i o n s o f polymer m o l e c u l e s were c o n s i d e r e d t o be t h e cause o f t h e s e d e v i a t i o n s . Aggregates o f m o l e c u l e s formed i n the p r o c e s s o f u r e t h a n e RIM p o l y m e r i z a t i o n would r e s t r i c t m o b i l i t y o f the r e a c t i v e groups and would d i s t o r t the r e g u l a r k i n e t i c s . Among t h e s e a g g l o m e r a t i o n s the r e c e n t l i t e r a t u r e mentioned the f o r m a t i o n o f microheterogeneous systems ( 1 ) , the c o a g u l a t i o n o f p o l y ­ mer m o l e c u l e s i n t o g e l p a r t i c l e s ( 2 ) , o r t h e b u i l d i n g o f s p e c i a l network c o n f i g u r a t i o n s ( 3 ) . I n t h i s s t u d y more a t t e n t i o n was p a i d t o t h e p o s s i b l e f o r m a t i o n of f r i n g e d m i c e l l e c r y s t a l l i t e s by r i g i d segments o f RIM f o r m u l a t i o n s . These c r y s t a l l i t e s c o u l d be c o n s i d e r e d t o be an i m p o r t a n t f a c t o r i n h i b i t i n g t h e m o b i l i t y o f the r e a c t i v e groups and c o n s e q u e n t l y c a u s ­ i n g t h e d e v i a t i o n s from t h e s t r a i g h t l i n e dependence o f the second order r e a c t i o n k i n e t i c p l o t . The i n t e r m o l e c u l a r f r i n g e d m i c e l l e n u c l e i c o u l d be formed under t h e i n f l u e n c e o f l a t e r a l i n t e r c o h e s i o n o f the r i g i d segments ( 4 , 5 , 6 ) . 1

Current address: 13255 Oak Ridge Lane, Rockport, IL 60441.

0097-6156/85/0270-0065S06.00/0 © 1985 American Chemical Society

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

66 it

REACTION INJECTION MOLDING the

the

rigid

segments

intermolecular The

total

fringed

network in

The

the

the

systems

fringed

would

phous

also

weaker point. be

If

The

be c o n s i d e r e d as

of

gel particles

or

separate phases

the mic-

sus-

system.

the

formed by a g g r e g a t i o n of

rigid

mobility

reactive

groups,

into

amor-

p h y s i c a l l y bonded

of

the

crosslinks

the

physical intercohesion

chemical

forces

as

the

covalent crosslinks. or

among t h e

crosslinks The

physical

completely decrystallized at

conditions

the

chemical

rigid

seg-

would

be

cross-

the

softening

c o v a l e n t bonds would

not

exposed

the

to

an e x t e r n a l

data,

could

micelle

two

factors,

be v e r y

nuclei

The elucidate micelle

RIM

elastomers

containing

what

degree

extensions

would

rearrange,

be o r i e n t e d

and the

crystallinity,

a high

residual

build-up

of

The

-what -to

could

and o v e r ,

direction

result

of

set

in

the

least

study

the

fringed

the

stress.

RIM

the

micelle

aggre-

Some b o n d s be

permanent of

set.

even moderate

content

of

formulations

the

as

a non-

inhibit

the

and thus

depress

the

b y the a g g r e g a t i o n o f

were

the

partially

micelle crystallites

this

d e v i a t i o n from

elastomers

to

fringed

the

to

physical, help

(6).

into at

the

p h y s i c a l bonds would

proportional

be expected should

c o v a l e n t , and

a substantial

w i t h RIM

a plasticizer

fringed

influence level

of

determined by the

rigid-flexible the

degree

reaction at

the

plasticizer

physical crosslinks

a n d how i t

literature

fringed

for-

crystallites. above

considera-

were:

what

of

300%

the

physical crosslinks

They

to

the

conversion level

and a f f e c t

extension

solvent

goals of

conversion

of

in

a permanent

portion

the

of

r e l a x a t i o n method c o u l d

some new i n t e r m o l e c u l a r

Incorporating of

what

cause

system would

When d e a l i n g a t

tions.

would

higher

would

volatile

according

densities,

stress

and a t

dependence.

crystalline

and s t r e s s ,

decrystallization

crosslink

by t h e

line

gates

formed,

of

temperatures to

in

(7,8).

crystallites

straight At

temperature

effective

determination

various

opment

cured

physical crosslink The

mation

stress,

micelle crystallite

(7).

at

arrays, formed.

broken.

fringed of

orderly

would be

would be an o r g a n i c p a r t

micelle crystallites

these

in

(4,5,6).

be p a r t i a l l y

Under

arrange

crystallites

system.

polymer

restrict

introduce

the

could

the

only

fringed

than

links

of

micelle crystallites

Formed by the the

could

of

polymer matrix

ments,

polymers would

micelles

p o l y m e r i c RIM

matrix

segments would not but

the

micelle crystallites

of

roheterogeneous pended

of

fringed

would

relate

to

segment r a t i o s the

content would

produced

the

deviation by the

would have inhibit

fringed

conversion level

at

on

the

point;

the

the

micelle

develnuclei,

deviation

point; -what lization

of

-what link

decay,

influence fringed type

of

the

rising

micelle

temperature would have

correlation

existed

determined by s t r e s s

exotherm-endotherm

on d e c r y s t a l -

crystallites; between the

relaxation

physical

cross-

m e t h o d a n d b y DSC

scans.

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

5.

DAMUSIS A N D LIN

Urethane RIM

67

Morphology Effects

Experimental Adiabatic Reaction. The experiments were conducted i n an adiabatic reactor constructed at the laboratory of the Polymer I n s t i t u t e consis­ ting of a 250 mis polyester container well insulated with a thick wall of a polyurethane foam poured i n s i t u . The adiabatic reactor, discussed and described i n a series of papers (9,10,11,12), was suitable for fast exothermic urethane RIM reactions. It did not require sophisticated insulated equipment. Because of the high speed of the urethane RIM reaction and poor thermal conductivity of the reactants, the heat losses were minimal, p a r t i c u l a r l y when the thermocouple was inserted into the center of the charge of the reactants. The Arrhenius equation and the energy balance equation were used to obtain a modified version of the equation for the second order adiabatic reaction k i n e t i c s . The Arrhenius equation f o r the second order reaction i s : k =A The energy balance equation i s : c

Ρ · ( T ) ^ ~ - k(-AH) p

*

ΔΗ

P

Κ

dt

The second order adiabatic reaction k i n e t i c equation was ed by combining Equations 1 and 2: P

*

«

-ΔΗ

A

. -AE/RT . 2 e

c

Δ

)

obtain­

(

3

)

dt

The above equation i n natural logarithm form i s :

Ρ · c (T) -ΔΗ p

l n

d

2

T

dF

...

ΔΕ

"

(

~ RT

4

)

The f i n a l form of the adiabatic reaction equation was obtained by moving the changeable value C from the r i g h t side of the equation to the l e f t side and replacing i t on the right side with the constant value of C : ο Ρ · Cjl) p ln CΛ -ΔΗ-C (^-) O \j v

J

P

dT dt

T

A

r>

ΔΕ ο ~ RT

=

/ C N (

5

)

ο

The l e f t part of t h i s equation was plotted on the ordinate, ana the Kelvin temperature r e c i p r o c a l 1/T on the abscisa. The necessary values were obtained experimentally, graphically, or were calculated by a regression method using a computer where: ρ = density, g/cc _ _ C = heat capacity, cal.g .Κ 1 q

1

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

68

REACTION INJECTION M O L D I N G

Τ t k H A R C

ο C

RIM

Formulations 1.

G,

concentration

were

with Various

Compositions

and H,

containing

evaluated in

sented

in

Table

tanediol lecular with

triol,

The

of

repeating

RIM

The

polyols at

of 60

based

blanket.

chanical

stirrer,

The

of

in

Time (Table

II,

The

initial

tomers, were

The plotted

the

the

pre­

1,4

A high

bu-

mo­

modified

flexible

segment.

favorable

RIM

polymer with

(Table

in

adiabatic were

reactants, in

a dry

were

syn­ poly­

process.

reactor.

thoroughly

polyols

and

demois-

quasi-pre-

container under

blending for

through

structured

I)

com­

to

regularly

polymerization

reaction

The

Such a

conditions

the

in

compounded

15

poured into

a

dry

seconds by a me­

the

an i n s u l a t i n g

rise

was

samples were

adiabatic

cover

continuously

taken The

containing

solution

into

reactor.

the

cen­

from

recorded.

the

withdrawn

reactor samples

At for

were

e x a c t l y measured amounts

prepared in back

advance.

titration

The

with

a

of

depletion standard

1638-70. rise

1,2,

of

in

temperature

experimentally

and 6 ) .

Other

a computer

concentration C

of

adiabatic

in

Τ

Κ,

values

were

II,

liter,

d a t a of

programmed by

columns

isocyanate for Table

and c o n c e n t r a t i o n

of

d e t e r m i n e d and r e c o r d e d

(Table

e q u i v a î e n t s per

and compiled

kinetic

were

glycerine

A regularly

flasks

method u s i n g

expressed

13.2%, are

reactants.

and C , were

calculated

of

elastomer

determined by the

columns

regression

segments

segments.

temperature

adiabatic C

the

a thorough

the

toluene

ASTM

t,

isocyanate

rigid

rigid

isocyanate content.

i s o c y a n a t e was

HC1 s o l u t i o n ,

-1

A,E,F,

to

compositions

reacting

reactants

Erlenmeyer

dibutylamine of

of

were

inserted

intervals

into

54.8

Their

rapidly

vacuum.

the

adiabatic

determination poured

elastomers

range from

constituted

formulations

After

charge

ten-second

the

equiv.-l

Segments. RIM

styrene,

of

urethane

RIM

on MDI,

A t h e r m o c o u p l e was the

of

C under

polymer,

of

reactor.

established

crystalize

five

nitrogen

ter

fast

structure

Kinetics

turized

the

t,

elastomer the

and f l e x i b l e

tended to

2.

Rigid Five

in

components of

formulation

rigid

(7)

segments

a n d 10%

the

an o r d e r l y

mer

of

a polyoxypropylene derivative

part of

Amounts

time

m e t h y l e n e b i s ( p h e n y l i s o c y a n a t e ) , MDI.

f

s u s p e n d i n g medium f o r position

isocyanate at

formulations.

adiabatic

acrylonitrile

amorphous

thesize

of

rigid

the

I.

and 4 , 4

10%

of

3,4,5,7,

each

of

the

as w e l l

as

density

a

and

five

values,

I.

all

these

five

elastomers

were

with dT dt

on

the

1/T,

ordinate

on t h e The

rigid and

5.

axis,

the

r e c i p r o c a l of

Kelvin

temperature

absclsa.

adiabatic

segments The

against

reactor

f r o m 54.8%

graphs

data for to

13.2%

all were

presented a clear

five

RIM

plotted

picture

of

elastomers in the

Figures

with 1,2,3,4,

influence

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

8).

elas­

the

5.

DAMUSIS AND LIN

rigid-flexible had

on the

ation the

segment

conversion

point.

rigid

In

Table

ratio level

Figure

segment

I.

6

of of

the

contents

Urethane

of

urethane urethane

adiabatic

RIM

RIM

the the

were

of ^ ^ ç s i g n a t i o n

69

Urethane RIM Morphology Effects

put

RIM RIM

elastomer

temperature

rise

the

data

devi-

versus

together.

Samples w i t h D e c r e a s i n g Rigid

formulation

reaction at

Contents

Segments

A

E

F

G

H

Components'^^ Polyoxypropylene derivative

of

TMP,

equiv. parts

by

1

1

1

1

1

2078

2078

2078

2078

2078

12

9

6

3

1.5

13

10

7

4

2.5

2392

1840

1288

736

460

2.869

2.482

2.041

1.413

0.987

moles/cc

0.705

0.857

0.986

1.200

1.350

% by

wt.

54.8

47.7

38.0

23.5

13.2

wt.

45.2

52.3

62.0

76.5

86.8

5138

3842

2921

2392

2092

3450

3260

1520

687

458

403

460

500

600

650

110

80

60

55

12

wt.

1,4-Butanediol, equiv. parts

by

wt.

Quasi-prepolymer, equiv. parts Initial of

by

wt.

concentration

isocyanate, equiv./liter

Theoretical

crosslink

density, C Rigid

χ

T

_

segment,

(calculated) Flexible

segment,

(calculated) Tensile 100%

Elongation, Permanent

Urethane

of

%

Elastomers (Table

plasticizer, elastomer

all

four

The this

of

group

plasticizer

tween

the

d a t a were using

Modified with Plasticizer.

containing 10%,

as

of as

and elastomer

elastomers

tests

of

these

is

presented

to

determine

inhibition

of

the

of

the

obtained experimentally,

obtained

are

presented

in

Figure

the

Table

effect

Β

with

III. in

the

evaluation

of

the

The

above.

of

content

forces

be­

kinetic

by a regression as

same

of

intercohesion

plots

RIM

modified

composition

conducted

aggregates.

calculated

a computer and g r a p h i c a l l y from t h e

The

main goal

lateral

crystalline

in

standard was

elastomer

15%.

were

The

The

segments

follows: D with

was

interspaces

rigid

elastomers

described above.

elastomers on

54.8%

t r i b u t y l phosphate,

these

reactor of

I)

C with

kinetic

adiabatic of

%

RIM A

psi

psi

set,

elastomer 5%,

% by

strength,

Modulus,

with

4

10

The

7.

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

method data

70

REACTION INJECTION M O L D I N G

Physical

Properties

from

demoisturized

well

blended

measuring

of

RIM

π

π

by I n s t r o n . 300%.

The

II.

The

are

the

Reactor From

Adiabatic

RIM

cured

1

°K

in

Elastomer

in

for

steel

1 hour

at

of

120

C,

physical

and

an

Tables

I

Ε

Adiabatic

from

The

molds

ex­

III.

a Computer Method

Using

Computer

dT

Κ

Τ

compounded

were determined at

Programmed U s i n g

a

were

determination

Programmed b y R e g r e s s i o n

Temp.T,

t,

sec.

for

compiled

Reactor Time

and molded

permanent s e t s

results

Values of

elastomers

and q u a s i - p r e p o l y m e r .

samples were

1 week and s u b m i t t e d

tension

Table

The

π

for

properties of

The

polyols

components were vacuumized

6 χ6 χ0.070 .

conditioned

Elastomers.

and p u r i f i e d

C (T)

-ln

p

dt

X

0.0

306.3

.3265E

10.0

309.3

.3234E

20.0

311.5

. 3 2 1 0 E --02

22.5

0.476

0.912

0.832

1.148

30.0

315.3

. 3 1 7 2 E --02

30.0

0.477

0-.868

0.754

0.754

40.0

320.3

. 3 1 2 3 E --02

55.5

0.479

0.809

0.655

-0.001

50.0

329.0

. 3 0 3 5 E --02

93.0

0.482

0.670

0.489

-0.816

60.0

345.0

. 2 8 9 9 E --02

93.0

0.488

0.514

0.264

-1.444

70.0

360.0

. 2 7 7 4 E --02

60.0

0.494

0.326

0.106

-1.927

80

370.0

. 2 7 0 0 E --02

33.0

0.498

0.204

0.042

-2.277

90.0

376.0

. 2 6 6 0 E --02

18.0

0.500

0.136

0.019

-2.482

0

120.0

382.0

. 2 6 1 7 E --02

9.0

0.502

0.062

0.004

-3.366

150.0

384.9

. 2 5 9 8 E --02

2.4

0.503

0.028

0.001

-3.732

180.0

386.10

. 2 5 9 0 E --02

1.5

0.504

0.011

210.0

386.7

. 2 5 8 6 E --02

0.75

0.504

0.003

0.0001 -5.004 0.0000 -6.682

Effects All

of

five

ments,

Temperature

RIM

and f o u r

evaluated

on P h y s i c a l

elastomers,

for

low

extension

100

C.

RIM

elastomers

crosslink of

50%

Crosslink

Crosslinks

densities

and a t

by s t r e s s

three

densities,

The

c ^ , were

values

be c a l c u l a t e d

and dimensions c

r

=

of

crosslink per

unit

as w e l l the

density

or

= gas c o n s t a n t ,

f

= =

25

C,

using

between the the

50

6:

crosslinks, The

8.313 area

effective

crosslinks

moles/cc

χ

10^ e r g s / d e g r e e - m o l e in

of

Kelvin the

degrees

original

cross-section

d y n e s / s q u a r e cm

extension

a

C , and

Equation

same e q u a t i o n .

moles of

10~"

= absolute temperature

L/L

of

calculated

using

Τ

in

were

equation are:

volume χ

unit

seg­

a plasticizer,

c,r

R

force per

Crystallites. rigid

r e l a x a t i o n method at

temperatures

number a v e r a g e m o l e c u l a r w e i g h t

could

amounts o f

A, modified with

α

M^

Induced by

containing different

ratio,

L=stretched

length,

L =original Q

length

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

5. DAMUSIS AND LIN

25

26

Τ Figure

1.

71

Urethane RIM Morphology Effects

Kinetic

plot

of

'

u r e t h a n e RIM s a m p l e A w i t h

54.8%

rigid

segment.

Figure

2.

Kinetic

plot

of

u r e t h a n e RIM

sample Ε w i t h

47.7%

segment.

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

rigid

72

REACTION INJECTION M O L D I N G

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

5. DAMUSIS A N D LIN

Urethane RIM Morphology Effects

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

73

74

REACTION INJECTION M O L D I N G d M

= density, ^ = number

£

' The of

and of ment

crosslink

ted

density

at

The

crosslinks

m e t h o d was

density,

crystallites.

caused

crystalline

and at

the

elastomers

at

levels

three

of

recorded

in

at

the

Tables

Table

Designation

to

stress the

densities,

RIM

of

the

with

and

based

NCO e q u i v .

(5,6)

low

.

exten­ experi­

covalent

calcula­ micelles

data obtained

were

a

Plasticizer

D

C

Β

weight

by

41.46

39.40

37.30

35.23

10.78

10.24

9.70

9.26

184

47.76

45.36

43.00

40.51

0.0

5.00

10.00

15.00

0.705

0.669

tributyl

phosphate Moles of chemical per

at

styrene

1,4-Butanediol on MDI,

seg­

physical

derivative

Quasi-prepolymer, Plasticizer,

as

density

rigid

crystalline

The

with

A

modified

acrylonitrile

the

obtained in

the

percents

TMP,

links

changes minus

Samples

RIM

of

determination

VII.

Urethane

Polyoxypropylene

for

relaxation

i n d i c a t e d how f a s t

and

chain

covalent crosslink

elevated temperatures.

VI

III.

of

aggregates acted

temperature,

densities,

decaying

network

relaxation.

moderately elevated temperature

determined c r o s s l i n k

crosslink

of

stress

by p h y s i c a l bonding of

ambient RIM

by

employed here

consisting

Exposing mentally were

relaxation

crosslink

crosslinks sion

between the

stress

total

g/cc

average molecular weight

10^

cross­

cc

of

0.606

0.636

polymer Tensile

strength,

Elongation, 100%

Modulus,

psi

Permanent

set,

DSC S c a n s

of

elastomers, 0.5

psi

RIM

Elastomers.

A,E,F,G,

meal/sec,

on

Discussions

and RIM

rigid

tent

of

tomers

The

that

any

170

3450

2320

1820

1450

120

100

20

26

deviation

elastomers

data are

in

the

in

Figures

relatively from the

point

elastomer the low

1,2,3,4,

lower 1,2

were

the

and 3 ) . line

of

in

Figure

and i n

The

conversion The

segment

Table the

higher

urethane

dependence

the 8.

on

level RIM

Line IV amount

the (RIM

con­ elas­

elastomers

did not

(Figures

RIM

K/min.,

from S t r a i g h t

and 5,

rigid

on f i v e

10

examined a t

Point

formulation. was

2786

run at

d e c i s i v e l y depended

amounts

straight

were

DSC-2

presented

Deviation

Figures

deviation

segment,

and F

G and H w i t h

The

The

data in

the

segment rigid

A,Ε

275

a Perkin-Elmer

C o m p o s i t i o n on t h e

Dependence. of

in

15±3 mg.

Results

indicated

2067

500

DSC m e a s u r e m e n t s

and H,

300-520°K.

of

4544

403 %

temperatures

Effect

5138

%

show

4 and

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

5).

5.

DAMUSIS A N D L I N

25

75

Urethane RIM Morphology Effects

26

27

28

29

30

31

32

33

1 _4 ο -1 γ x 10 , Κ Ί

F i g u r e 7.

310

E f f e c t o f p l a s t i c i z e r on t h e c o n v e r s i o n l e v e l a t deviation point.

330

150

370

39(3

?ÏÔ

ÂÎ)

450

470

the

490

Τ (°k) F i g u r e 8.

DSC scans o f RIM e l a s t o m e r s w i t h h a r d segment c o n t e n t s i n t h e range o f 5 4 . 8 - 13.2%.

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

76

REACTION INJECTION M O L D I N G A

Lin

formulation

in

his

diisocyanate (MDI),

similar

doctoral -

our

and L i n ' s

anate

at

level

was

triol-1,4

diisocyanate

was

weaker

than

Another on

that

deviation

paper of

1,6

hexamethylene

urethane

size

triol

D.

Lipshitz

no

micelle

crystallites

as

plot

the

Table

70:30.

18%

effect

straight

at

diisocy­

conversion

diisocyanate

line

of

at

the

line

of

RIM

alipha­

dependence

elastomer

d e p e n d e n c e was

and C h r i s t o p h e r

(HDI),

in

the

W.

composi­

taken

Macosco

p a p e r was

an a l i p h a t i c

prepolymer,

physical

Conversion from

of

level

from

(15).

based

on

diisocyanate,

cured with

a medium

and

molecu­

crosslinks.

Therefore,

data resulted

in

the

a straight

kinetic

line

with­

point.

IV.

Designation

diisocyanate,

diisocyanate. effect

presented

adiabatic reaction

any d e v i a t i o n

of

diisocyanate

an e q u i v a l e n

did

out

T.B.

type

conversion

The

from the

straight

(TPG)

of

70:30.

the

diisocyanate

with

of

by

the

b a s e d on a l i p h a t i c

ratio

aromatic

formulation

58%

b a s e d on a r o m a t i c

deviation the

glycol

formulation of

weight

ratio

from

Stephen

on t r i p r o p y l e n e lar

of

in

b a s e d on a r o m a t i c

elastomer

A,

weight

causing

the

This

RIM

butanediol

reported

was

based on a l i p h a t i c

example i n d i c a t i n g

the

The

the

elastomer

butanediol

tic

tion

for

triol-1,4

A was

difference

cyclohexane (p-BDI).

was

the

elastomer

only

f o r m u l a t i o n was

point for

our

The

f o r m u l a t i o n was

1,4-isocyanatomethyl deviation

to

thesis.

RIM

the

Levels

at

Straight

Deviation

Points

L i n e Dependence H

A

Ε

F

G

54.34

47.70

37.60

23 . 3 0

18.00

25.00

39.00

no

Elastomer Content

of

rigid

segment,

%

Conversion

level

deviation

Effect The

of

point

point,

%

Plasticizer

effect was

of

apparent

addition,

the

(Table

elastomers

V,

The bited link

Effect

of

1. ing

formation

densities of

Elevated

amounts of

crosslinks

of

V,

Figure

level

at

deviation

(Figure

rigid by

the

Deviation

level

8).

At

at

the

10%

point

Point. deviation

of

plasticizer

increased

twice

elastomers segments

the

RIM

elastomer

The

physical

decreasing with the

on Decay

A,E,F,G

crosslinks

into

aggregates.

A

inhi­

cross­

increasing

9).

Temperature

physical caused

plasticizer

crystalline

significantly

The

at

(Table

of

elastomers

segments.

amounts

of

were

Level

conversion

deviation

A and C ) .

plasticizer

RIM

on the

conversion

incorporation

the

amount

rigid

on C o n v e r s i o n

plasticizer

very

13.20

at

of

A,E,F,G

resulted

in

Crosslinks.

d e c r e a s i n g amount

and H

densities

crystalline

Physical

and H w i t h

(Table

I)

successively (Table

VI,

of

with decreas­ decreasing

Figure

aggregates degraded with

10). the

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

The rising

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

9.

Decay of physical c r o s s l i n k density with r i s i n g temperature i n the presence of p l a s t i c i z e r .

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

Figure 10.

Decay of physical c r o s s l i n k density with r i s i n g temper­ ature at various r i g i d segment amounts.

α 2 ο

Ο Ο r

3

m

a

δ

- J 00

5. DAMUSIS A N D LIN temperature. decreased 100 of

C s t i l l

crosslink

100 to

of

C.

the physical After

s t i l l did

holding after

the

lost

covalent rigid

crosslink

Table

even

V.

at

Effect

Content

density

density.

The data

Table

VI.

of P l a s t i c i z e r

^ * * ^ ^ o f

Moles Of Of

in

p e r 10

chemical actual

that

100 C

fraction

on the r e t e n t i o n

of

physical

on the Conversion L e v e l

%

18.0

of

B

C

D

575

10.0

15.0

28.0

38.0

45.5

Ô7Ô

%

Rigid

Segment C o n t e n t

o f RIM b y S t r e s s

o f RIM

^^^^Se^ment

on

Crosslink

Relaxation

Ε

A

Rigid

cc of

at the

H

G

F

54.8

47.7

38.0

23.5

13.2

0.705

0.816

0.972

1.20

1.36

Polymer^*

network

network, 28.10

12.36

10.63

5.13

5.20

21.82

7.34

5.58

3.02

3.10

100°C

11.00

3.22

1.31

1.04

1.12

20.82%

3.50%

-

-

Physical broken

2.

temperature

crosslinks at 100°C

not

in

37.21%

1 hr.

RIM e l a s t o m e r s

cizer.

A , B , C and D with

The c o n v e r s i o n l e v e l

increasing

fringed

to the elastomer micelle

plasticizer,

decreased.

crystallites,

5% p l a s t i c i z e r ,

decrease

added

the tensile

and s i g n i f i c a n t l y

(Table

Figure

9).

V,

thus,

crosslink

elongation, VII,

(Table

formulation

the physical

With

i n c r e a s i n g amount o f

at deviation points

amount o f p l a s t i c i z e r

plasticizer

ficantly

of

the content

50°C

Room

form

indicated

which

at

p h y s i c a l and

chemical

of

were

dependence,

and even a s m a l l

A

Effect

^^^^.JJesignation

F

G and H,

Point

Density

Crosslinks

effect

o f RIM

level,

The elastomers

at

closer

the physi­

the elastomer line

density

one hour

Ε and F were

A p p r o x i m a t e l y 20.8% o f

crosslink

of p l a s t i c i z e r ,

Conversion

crosslink

Approximately

holding after

the straight

rapidly

but even a t

100°C.

Deviation Designation

s t i l l

at 100°C.

segments had a d e c i s i v e

crosslinks,

segments,

the covalent

the elastomers

density.

one hour

a l l physical

rigid

temperature,

t h e e l a s t o m e r Ε a n d 3.5% o f

n o t show a n y d e v i a t i o n f r o m

have

were

at 100°C,

crosslink of

rising

the polymer content.

crosslinks

one hour

crosslinks

with

the l e v e l of

p e r 10^ c c o f

the covalent

cal

A , c o n t a i n i n g 54.8% o f density

d i d not reach

0.705 moles

37.2%

of

Elastomer

in

79

Urethane RIM Morphology Effects

increased

Figure

inhibited with

density

9).,

Addition

the tendency

the increasing was

plasti­

with the

content

significantly

to the elastomer A, d i d not

strength decreased

(Table

III,

of to

Β ) ,

the physical

increasing temperature,

signi­

increased

crosslink

density

the elastomers

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

80

REACTION INJECTION MOLDING

with

low

ties

at

quantities the

Table

or

same r a t e

VII.

plasticizer as

Effect

the

of

Plasticizer

Density ^^^^.gesignation ^ ^ o f Crosslinks Moles

per

of

lost

the

physical crosslink

non-plasticized elastomers

on the

by S t r e s s

Actual

densi­

(Table

V).

Crosslink

Relaxation

A

Β

C

C

0.0

5.0

10.0

15.0

0.705

0.669

0.636

0.606

28.10

17.10

14.10

12.71

37.10%

31.77%

30.19%

27.54%

RIM

Plasticizer i ^ ^ ^ ^

10

cc

o r ^ » ^ ^

Polymer Of

chemical

Of

actual

network

p h y s i c a l and

chemical

network,

Room

temperature

50°C 100°C Physical

crosslinks

broken

at

Permanent

Set

permanent

set,

elongation. extension,

not

100°C in

of

1

hr.

Urethane

as

The

RIM

reported fringed

VS.

in

Content

Tables

I

seemingly realigned in

creased

set

with

data the

in

Table

The

permanent

decreased

The

correlation

rigid the of

set

linear

the

of

the

RIM

and the

the

the

were more pronounced w i t h

the

with

the

lower

The

RIM

one h o u r

at

elastomer

A,

exposed

crosslinks.

The

measurements

occurred

determined w h i c h was

by the applied

an a d d i t i o n a l

dissipation at

to of

the

the

of

higher

rigid

able

of

area

of

was

content

to

the

retain

high

stretch

and

(17).

The

permanent set setments

III

of

the

amount

de­

the

indicated of

content of

RIM

that

plasticizer of

the

(6). the

plasticizer

i n d i c a t e d the

on

presence

the

(167°C). of

rigid

stress

only

crystalline

a temperature

urethane

These

peaks

segments

process of

the

relaxation

37.2%

of

its

than

test

a g g r e g a t e s by the Seemingly,

stress

decrystalization

the

DSC

higher the

relaxation of

after

physical

a p p r o x i m a t e l y 50

in

enhancing

300%

such

segments.

r e l a x a t i o n method.

the

the

DSC s c a n s o f

440°K

stress

factor

to

systems.

content

100°C,

of

indirectly

endothermic peaks in

rigid

Table

data with

effect

densities,

appeared

the

in

i n c r e a s i n g amounts

aggregates in

The

elastomers

with

of

the

The

obtained at

exposed

direction

of

data

permanent set

physical crosslink

DSC S c a n s .

set

Segment.

was

permanently stable

indicated that

content

permanent

segments,

crystalline

I

decreasing

formulation.

Rigid

micelle crystallites,

f o r m e d new p h y s i c a l b o n d s w h i c h w e r e permanent

of

and II,

than

stress

m e t h o d was

physical

crosslinks.

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

5. DAMUSIS A N D LIN

81

Urethane RIM Morphology Effects

Conclusions RIM

elastomers

a r e more

formulations nates

the

RIM tion

the

the

rigid

amounts

of of

physical

crosslinks.

The

crystalline

tallites,

a c t as

temperatures. The ments

line

decay

of

linear

diols

the

identical

aliphatic

diisocya-

the

the

lower

straight

line

the

conversion

dependence.

crystallizing

c o m p o n e n t s show no

dependence

the

plasticizer crystalline

of

included in

kinetic RIM

elastomers

fringed

containing a higher to

inhi-

development

and d e c r y s t a l l i z e

show m o r e r e s i s t a n c e

devia-

plots.

formulations

aggregates and the

aggregates, probably the

segments

occurs at

from

physical crosslinks

RIM

crystallizing

and l i n e a r

segment c o n t e n t ,

without

straight

formation

aggregates than

diols.

deviation point

the

Small bit

crystalline

on c y c l o a l i p h a t i c

elastomers

from

form

linear

higher

at

on a r o m a t i c d i i s o c y a n a t e s and s h o r t

to

based

and short The

level

based

inclined

micelle at

content

thermal

of

crys-

elevated of

rigid

decay.

physica

a highe

r e l a x a t i o n method. Seemingly, enhances

the

stress

is

another

decrystallization

of

factor the

besides

physical

temperature

that

crosslinks.

Literature Cited 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16.

Dusek, K. J. Pol. Sci. 1967, 16, 1289-1299. Bobalek, E.C.; Moore, E.R.; Levy, S.S.; Lee, C.C. J . Appl. Sci. 1964, 8, 625. Lipatova, T.E. Pure and Appl. Chem. 1975, 47, 23. Flory, P.J. J. Amer. Chem. Soc. 1962, 84, 2857. Wunderlich, B. "Macromolecular Physics"; Academic: New York, 1976; Vol. II, pp. 16-17. Meares, P. "Polymer Structure and Bulk Properties"; Van Nostrand: London, 1965; pp. 117-118, pp.154-156, pp. 230-233. Rodriguez, F. "Principles of Polymer Systems"; McGraw-Hill: New York, 1970; pp. 3, 29 and 34. Samuels, R.J. "Characterization of Deformation of Polycrystalline Polymer Films"; Sweeting, O.J., Ed.; Interscience: New York, 1968; Vol. 1, pp. 258-260. Parts, A.G. Australian J. of Chem. 1959, 11, 251. Douglas, J.M.; Eagleton, L.C. I. & E. C. Fundamentals 1962, 1, 116. Allen, E.L. I. & E. C. Fundamentals 1969, 8, 828. Camargo, R.E.; Macosko, C.W.; Tirrel, M.; Wellinghoff, S.T. Pol. Eng. Sci. 1982, 22, 719. Damusis, A.; Asch, W.; Frisch, K.C. J . Appl. Pol. Sci. 1965, 9, 2965-2983. Lin, T.B. Ph.D. Thesis, University of Detroit, Detroit, 1982. Lipshitz, S.D.; Macosko, C.W. J. Appl. Pol. Sci. 1977, 21, 2029-2039. Turner, R.B.; Spell, H.L.; Vanderhider, J.A. "Urethane RIM Elastomers"; Kresta, J . E . , Ed.; Plenum Press: New York, 1982; p. 63.

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

REACTION INJECTION MOLDING

82

17. 18.

Sweeting, O.J.; Lewis, R.N. "Molecular Constitution of Polymers"; Sweeting, O.J., Ed.; Interscience: New York, 1968; Vol. I, p. 35. Cobler, J.G.; Long, M.W.; Owens, E.G. "Crystallinity and Melting Temperature"; Sweeting, O.J., Ed.; Interscience: New York, 1968; Vol. I, p. 728.

RECEIVED October 5, 1984

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

6 Structure-Property Relationships in RIM Polyurethanes 1

1

2

1

1

N.BARKSBY ,D.DUNN ,A.KAYE ,J. L.STANFORD ,and R.F.T. STEPTO 1

Department of Polymer Science and Technology, University of Manchester, Institute of Science and Technology, Manchester,M6O1QD, England Department of Mathematics, University of Manchester, Institute of Science and Technology, Manchester,M6O1QD, England

2

Polyurethane (PU) materials have been formed by RIM using a commercia various compatibl with slurries containing polyol blends and glass fibres. The RIM equipment used, modified with a special dosing unit for processing glass fibre/ polyol slurries, is described. Polyol blend composition, varied by using different proportions of high and low molar mass triols and a chain extender, resulted in PUs with various hard block contents and crosslink densities. Tensile, flexural and dynamic mechanical properties at different temperatures have been investigated for the various PUs which ranged (at ambient temperature) from soft elastomers to stiff, yielding plastics. In this study, the use of incompatible polyol blends produced well phase-separated PUs for which the property-temperature dependence (-50 to 100°C) is much less than for PUs formed from compatible polyol blends. At elevated temperatures (>150°C), PUs formed from compatible polyol blends, containing higher proportions of low molar mass triols, retained their mechanical integrity compared with the rapid deterioration, (due to hard-phase melting), observed in the phase-separated PUs. Filled PUs showed the expected increases in stiffness and strength with concomitant decreases in elongation. Property changes in these composites are related to fibre loading and aspect ratio. Formulations f o r producing polyurethanes (PUs) by reaction i n j e c t i o n moulding (RIM) usually contain mixtures of polyols and d i o l s i n order to achieve the desired properties i n the moulded part. The present work forms part U ) of a systematic investigation into the e f f e c t s of polyol blends and glass f i b r e s on the physical properties of u n f i l l e d and f i l l e d PUs formed by RIM. In the case of u n f i l l e d PUs, by using a multi-component polyol mixture, i t i s possible to investigate the effects on properties of (a) polyol structure, molar mass and funct i o n a l i t y , (b) the r e l a t i v e proportions of diol-based hard blocks and triol-based soft blocks and (c) polyol blend compatibility. The

0097-6156/85/0270-0083S06.00/0 © 1985 American Chemical Society

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

84

REACTION INJECTION M O L D I N G

properties aspect RIM as

of

ratio

filled

PUs

are

determined

(length-to-diameter)

composite materials.

In

either

isocyanate/polyol reactant

used

during

RIM

will

RIM-PU R e a c t i o n The

also

of

case,

ratio,

affect

triol and

VM10

(all

ethylene

containing triol

ICI

PBA1478

catalysts,

tipped with

weight

ratio

and

in

present

POP

is

85:15.

triol

lower

molar

it

was

M(720g m o l " )

mass used

Two

prepared, PUs

using glass

milled

(ex.

fibres

70um a n d

of

uniform

Series which of

code

polyols

and

including the

ence, a

3%

excess

of

ot

is

shown

dosing

unfilled the

side

axial

in

to

the

in

polyols

is

(POP) units

5,260g

glycol

(EG)

as

in

mol" , 1

w i t h LHT240,

b a s e d o n VM10

a

chain

unfilled glass

and f i l l e d

(CSG).

mean l e n g t h

17um, in

PUs

and

order

were

various

Table

I,

expressed

stoichiometric of

diamine

in

100),

in

ratios

The

summarised by

(PB)

weight

triethylene

(multiplied

equivalents

diameter

blends

the

throughout.

are

with

hammer

respectively.

of

catalyst

The

Fibreglass)

compatible polyol

A mixture as

isocyanate

II.

Pilkington

represents

RIM

equival-

isocyanate

and

971

Equipment

produced in-house, up

1 which

to also not

in to

pump

shows require

contain

by

the

a dosing

with

is

thus

of

unit

was

development

polyol

usually used,

unit

simplifying of

the

the

fibres

con-

slurries in

of

and

side.

wear

glass

which,

90

processing

isocyanate

most

parts.

shown

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

have

commer-

some f o r m o f

special wear-resistant

dosing

the

and r a p i d

unit

of

HP90 m a c h i n e

normal

abrasive

and d i s p e n s i n g

using

throughput the

special dosing

polyol,

the

development

machine, model

right) For

the

1 for

f i l l e d - R I M machines a novel

(top

avoid excessive

metering

pump f i t t e d

diagram of

slurries.

Figure

(mpl)

using

Engineering

a maximum m a t e r i a l

polyol

would

shown

indirectly

machine,

of

handle

filled-RIM,

cially-available, present

of

represent

ratios

1001

was

(htp)

that

slurries,

displacement

I

used

HP90 w o u l d

tank

be a c h i e v e d

of

POP:POE

admixture

and

A schematic flow

1

piston metering

tained

T32/75

(ex.

1.5mm

by weighted

operating

Figure

to

(M)

strand

based on a V i k i n g

s~ ).

used

PUs,

Generally

to

of

hydraulic

polyol

Thus,

materials

in

unit

T32/75 Carbide)

hydroxyl.

(1.5kg

1

with

in

a n d d e r i v e d RIM

excess

equipment

capable

Union

units,

had nominal

and E G . was

and O p e r a t i o n PU

included

a polyoxypropylene

PBA1478

various

isocyanate/hydroxyl

filled-RIM

thickness

studies

(ex.

and S e r i e s

fibres

Table

LHT240

System Index.

kg m i n "

using in

reactants

a 4%

HP90,

PUs

dilaurate

1041

A range

Bros.)

and d i a m e t e r ,

T32/75,

Description

triol

materials I

and chopped

chopped

numbers

dibutyltin

polyol-based as

the

RIM

incompatible

(HMG)

Unfilled

the

the

of

Series

Turner

12um: length

II:

series

designated

hammer m i l l e d of

these

and e t h y l e n e

1

b a s e d on 4 , 4 - d i p h e n y l m e t h a n

I:

the

such

isocyanat

thereof,

Series

in

is

(POE)

(2) were

and

and

in

properties.

an i n c o m p a t i b l e b l e n d

The

and i s

temperature

b l e n d and D a l t o c e l

LHT240

and T32/75

The

studies

used

extender. omers

loading

processing variables

materials

polyol

polyoxyethylene

the

of

PBA1478

Polyurethanes),

glycol.

added

the

the

incorporated

Systems

isocyanate,

ex.

by

fibres

mould

final

commercially available materials

Suprasec

primarily

glass

positive In

the

.BARKSBYETAL.

Structure-Property Relationships in RIM Polyurethanes

Nps

F i g u r e 1. Schematic f l o w diagram of the HP90 RIM machine showing the p o l y o l s l u r r y d o s i n g u n i t and o n - l i n e rheometer. Key: h t p , h y d r a u l i c tank ( f o r m e t e r i n g p o l y o l ) ; mp, m e t e r i n g pumps (1 and 2 ) ; JÊpr/hpr, l o w / h i g h p r e s s u r e r e c i r c u l a t i o n loops i t / p t , isocyanate/polyol tanks; i f / i r , isocyanate feed/return l i n e s ; p f / p r , p o l y o l f e e d / r e t u r n l i n e s ; mh, m i x i n g head; mc, mould c a v i t y ; t b , t r a n s f e r b a r r i e r ; h d c , h y d r a u l i c d i s p l a c e m e n t c y l i n d e r ; p s , p r o x i m i t y s w i t c h ; b v , b a l l v a l v e s (1 and 2 ) ; v i s , viscometer.

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

86

REACTION INJECTION MOLDING Table

I.

Polyol

Blends

and S l u r r i e s to

(i)

= Incompatible

*Slurry

Polyols;

containing

Used

F o r m RIM (c)

18%HMG;

VM10

= Compatible

"^Slurry

Isocyanate

Polyols

containing

5% C S G

System

Polyurethane

Viscosity(25°C)

Polyol Blend/Slurry

with

PUs

Poise

from

Index

VM10

S Ε

PBA1478(î)

11.3

PU1478-97I

R

PBA1478(i)

11.3

PU1478-104I

1041

971

I

PBA1478(i)

11.3

PU1478-114I

1141

Ε

PBA1478-H18*

15.6

PU1478-H18

1041

S

PBA1478-C5+

20.0

PU1478-C5

1041

I S 1? £j R τ

1

1 £i7 o b

7.8

PU621

1031

PB52l(c)

7.7

PU521

1031

PB42l(c)

7.5

PU421

1031

PB22l( )

4.3

PU221

1031

ΡΒ401^)

11.1

PU401

1031

c

II in

ΡΒ82ΐ(°) PB62l(c)

greater

transfer slurry

is

ised

bottom ball

nitrile

in up

of

10

(vis)

during

viscometer The

fer

ball

valve

(bv1)

which

of

polyol

for of

The of

system

is

abrasive

fer with

and by

under

flow

through fuller the

slurry. there the

by

are

ensuring

is

less

description

switch

the

the (3).)

a

operates

side

into

the

piston the

trans­

and e x p e l l s

the

re­

the

transfer

no m o v i n g p a r t s stress, of

total of

equivalent

the

top

swept

the

thus

the

maximum v o l u m e

stroke

an

of

precise

of

minimal

the

the

of

paper

using

(mp1)

Overfilling

that

than

through

viscometer

which

effectively

slurry.

the

expelled

determined

expanded

to

the

(with

from

either

succeeding

advantage of

subjected

controlling

low

The

pressur­ and

pump

(hdf)

diaphragm is

being of

fluid

a cont­

2

is

the

and d i s p l a c e s

with negating

transfer volume of

cylinder

the

of

the

trans­

piston

(ps).

During machine operation recirculated

slurry

either

cylinder

proximity

is

valve

(hdc)

hydraulic

prevented

barrier the

nature

in

from metering

polyol

is

tank

and m a t e r i a l

allows or (A

given

by b a l l

areas

that

the

displacement

PUs

expelled

of

shut

by

25°C c a n be

cylinder

polyol

diaphragm i t s e l f

are

which

the

polyol

(hdf)

at

differential

rubber

the

is

slurry fluid

dispensing

amount

barrier

processing

operation

cylinder)

barrier

is

hydraulic

barrier.

quired

dispensing (bv2)

for

(pt)

is

the

fluid

slurry

controlled

valve

(mh)

(allowing

this

During

is

feature

between h o l d i n g

r h e o l o g i c a l measurements.

hydraulic

amount in

of

tank

ball

and i t s

amount

volume the

3-way

Polyol

material

barrier

main

barrier,

displacement

holding

of

the

transfer

diaphragm.

stirred

transfer

head

which

from h y d r a u l i c

1 closed).

the

in the

and f l o w

barrier,

mixing

2

Inside

rubber

bar

the

valve

transfer the

Figure

a separate, to

through

in (tb).

separated

flexible, ained

detail

barrier

but

pressure

prior

to

dispensing,

(independently

of

the

materials mixing

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

are

head)

to

BARKSBY ET AL.

Structure-Property Relationships in RIM Polyurethanes

F i g u r e 2. Schematic diagram of the RRIM d o s i n g u n i t used f o r p r o c e s s i n g p o l y o l s l u r r i e s . Key: p t , p o l y o l h o l d i n g t a n k ; c a , compressed a i r ; sm, s t i r r e r motor; h d f , h y d r a u l i c d i s p l a c e ­ ment f l u i d ; t b , t r a n s f e r b a r r i e r ( n i t r i l e r u b b e r ) ; p s , p r o x i m i t y s w i t c h ; mhf/mhr, m i x i n g head f e e d / r e t u r n l i n e s ; h s , h y d r a u l i c s u p p l y from m e t e r i n g pump 1; b v , b a l l v a l v e s (1 and 2 ) ; v i s , viscometer.

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

88

REACTION INJECTION M O L D I N G

ensure

homogeneous m i x i n g

Considering between (bv2)

transfer

as

holding using anate

tank

smooth

machine

a low

through

is

in

The

tank

(pt)

machine in

can then

into

adjustable

Thus, sizes

orifice

orifice

ratios,

from

give

Efficient

200

should

mixing as

bar

is

is

terms

by

diameter

mass

diameter of

and v i s c o s i t i e s by

psi)

fully

inser­

withdrawn, the

circular

jet.

established,

setting

pressure

the at

annular

the

stream v e l o c i t i e s

of

conditions

ori­

mixing about

in

the

100 head

(4)

of

50

an impinge­

as

given

(pintle

value

is

orifice

zero

(Re)

number

equation

mixing

number

the

the

impingement

Reynolds

form

Q,

the

dia­

the

simplest

the

fitted

of

of

a critical

d is

splits

varied

a c h i e v e d when f l o w

In

fluid.

12mm d i a m e t e r , head

can be c o n t i n u o u s l y

achieved

(3,000

exceed

where

a

a maximum ( p i n t l e

ment m i x e r . Reynolds

to

potential

with

d e f i n e d by the

defined in its

head

the

psi)

mixing

is

effectively to

corresponding reactant

turbulent

at

enabling 2 pairs

head

sizes

throughputs

impingement m i x i n g to

mixing

and i s o c y a n a t e to

The

to

and i s o c y ­

stream

completely shut)

giving

value

polyol

chamber.

c o m p l e t e l y open)

sizes

thereby

(Apr)

m o d i f i e d HP90

with

the

its

loop

pintle

reactant

reactant

efficient

of

the

the

valve

be switched

etc.

(3,000

fitted

operation,

streams

c a n be v a r i e d

orifice

MK12-4K-F,

streams

c i r c u l a r mix

a s s e m b l i e s whose

jets.

head,

4

bar

conjunction with

During

through and from

which both p o l y o l

jets/channels

conditions.

recirculated

recirculation

a p p r o x i m a t e l y 200

used i n

piston.

supplies

externally whose

mixing

a Krauss-Maffei

the

nozzle

of

head

metrically-opposed

the

is

pumped t o

pressure

pump ( m p 2 ) .

pressure

mixing

reactant

are

slurry

and h o l d i n g

isocyanate is

r e c i r c u l a t i o n mode

flow

self-cleaning

fice

(tb)

whilst

temperature/viscosity

polyol

c a n be r e c i r c u l a t e d i n d e p e n d e n t l y through

The

With

and s t e a d y

p o l y o l or

through

metering

dispensing

ted,

,

barrier

(it)

pressure

ensure

mix

1

described,

the

a high

Figure

for

flow

and u

throughput

is

of

about in

the

for

a circular

whose

orifice,

dynamic v i s c o s i t y

fluid,

is

g i v e n by

of

the

(5) (2)

where

ρ is

pressure complex simple by

the

drop

fluid

annular

orifice

definition

eliminating

density,

on e n t e r i n g of

d

the

k

is

a nozzle

mixing

arrangement in

Equations

factor

chamber. in

the

and Δ Ρ

However,

Krauss-Maffei

1 and 2

is

is

with

head,

impossible

d can an approximate e x p r e s s i o n

for

Re

the the

and

a only

be o b t a i n e d

Thus, (3) Calculated

values

and m a c h i n e reactants

of

described

During

Re

variables in

using

are

Equation

summarised

Table

in

3

,

together

Table

II

for

with the

materials various

I-

RIM-PU p r o c e s s i n g , t h e

mixing

h e a d was

fixed

to

a

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

6.

BARKSBY ET AL.

Table

II.

R

e

a

Materials

r

t

a

n

t

.

(ii)

μ

Blends(25°C):

Polyol (i)

and M a c h i n e Parameters

Viscosity,

Reactant

Polyol

(

( f c g

s

_

(kg

1 }

RIM

Processing

Reynolds

ρ

m-3)

Number,

0.345-0.522

1036

270-615

15.6

0.480

1170

206

PBA1478-C5

20.0

0.439

1068

150

0.178-0.238

1220

1980-2291

(700mm)

1.0

steel

to

of

mould

a runner

the

cavity.

The

continuously

increasing

the

about

Re

in

moulding

for

and w i t h Tables

demould

I

times

toughness

Unfilled

range

the

cessing.

of

III.

each

60s

plaques,

static

the

in

aftermixer

entire

length

a hydraulic

700

χ

400mm,

produced

(giving

and mass filling were

press,

was

predetermined

reproducible

systems

studied.

approximately

throughputs times

used

of

using

of the f o r m u l a t i o n

plaque

mould

about

of

during

from reducing plaque

of

about RIM

a

1kg

mould­

reactants 1s

given

and p l a q u e

processing .

thickness

due

to

alter-

Materials on PU1478 m a t e r i a l s

Table

Effects

,

result

thickness

Typical

Table

U"-shaped,

running

clamped

6mm w e r e

densities

plaque

columns of

1 to

for

and II

studies of

f l

wit

a 3mm t h i c k

RIM-PU

Initial erties

a

system

mould,

Rectangular

the

conditions

Typically,

with

temperatur

150°C.

thickness

fitted

and gate

circulated

and

Density,

Throughput, Q

during

Slurries(25°C):

connected

in

)

Used

PBA1478-H18

rectangular

ing)

p

4.0-20.0

Isocyanate(35°C):

to

89

Structure-Property Relationships in RIM Polyurethanes

tensile III

.

Tensile of

Plaque

(*Filled materials

showed

effects

and System Index stress-strain

Increases, Properties

(23°C)

using

data are

of

on p h y s i c a l

during given

particularly

Thickness,

formed

used

in

incompatible

and

polyol

in

prop­

pro­

the

modulus,

PU1478

System Index

RIM

first

4

elongation

Materials, Filler b l e n d PBA1478

at

1041) Material

PU1478-

PU1478- PU1478-

PU1478-

PU1478-

PU1478-

971

971

1141

H18*

C5*

2mm

Property

Plaque

1041

y κ

J mm P l a q u e

s

—

Modulus (MN

m" ) 2

296

225

222

289

516

344

Strength πΓ )

21

21

24

27

27

20

Elongation(%)

198

171

158

145

120

53

32

26

27

29

27

8

(MN

2

Toughness (MJ

m"3)

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

90

REACTION INJECTION M O L D I N G

ations

in

within

the

(6-8)

the

the

ture

proportionsof

sections highly

gradients

of

skin-co-core layers

these

exothermic

across

the

from the

mould

gelation behaviour

in

surface

to

III

processing (1041

and

decrease modulus

RIM

in

data,

shown

in

terms

the

of

influence

during in

polyol

the

in

the

dispersed

of

T32/75

-

tive

purposes,

used

to

ratio

in is

evaluated from In

later,

general

c a n be

the terms,

behaviour

interpreted

on g e l a t i o n

PB221 d e f i n e d

PUs

to

weight

these

with

34

the

based

PB821

to

POE/POP

of

RIM

(9)

and phase

blends

on the

in

Table

1

whilst

soft

Ideally

blocks

of

T32/75,

average molar

hard

HBs

formed

masses

in

the

triol

T32/75

The

curves

and

compati-

block

(HB)

RIM

triol For

PUs

mixtures

between 2,300

composition range.

also

LHT240

these

from

com-

were

maintaining

the

(SB)

incompatible

based

increasing potential 53%.

same p o l y o l

from

on the

PUs

proportions

a n i n c o m p a t i b l e b l e n d PB401

f o r m PU401

to

compara-

( c o n t a i n i n g no LHT240)

and EG r e s u l t i n g

in

a

was

59%

content.

Tensile the

StressrStrain.

progressive

soft,

ductile

change

in

elastomer

the

(PU821)

(PU221).

Preliminary

even phase i n v e r s i o n

the

or

highest

may b e t h e hard

HB

and lowest

result

of

possible

the

degree

polyol

on the

of

blends

similar

tensile

properties

pected PU521

on the

of

the

various

RIM

where

the

effects

of

evident.

(increasing

In

the

an e s s e n t i a l l y

shows in

soft

from the

little

Table

alone

use

IV.

This of

is the

respectively

density)

together

with

PU401

This

is

PU221,

shown

(

molar

43%) for

in

in

PU401. Figure PU401,

incompatibility reducing

increases

in

ex-

compared w i t h

versus with

be

reduced

a n d 59%

compatibility

is deduce

compatible

to

5,300

to

It to

apparent difference

compatible polyol-based series,

crosslink

of

curves

HB-content

PU821

(with

behaviour

continuous

and lower

Behaviour.

phase

phase.

behaviour

a

plastic

PU221

yielding

a n d PU621

from

yielding

1

materials polyol

illustrate

extensive

and the

compensating e f f e c t s

Modulus-Temperature

for

of

PU521

2,000g m o l " )

compared w i t h

4(a) more

the

M)

resulting

summarised

of (

materials

RIM

probably occurred in

stress-strain

PU1478-1041) as

3(a)

of

low m o l a r - m a s s ,

comparison of

basis

triols

a n d PU621

Flexural

to

Figure

indicated that

mixed t r i o l

of

in

series

a high-modulus,

has

phase separation

(itself

mass

studies

dispersed, basis

since

to

plasticisation

phase by a w e l l

not

DSC

shown

second

mixing

M

the

properties

modulus-temperature

4(b)

reactant

of

isocyanate

increases,

tensile

series

in

range

over

1

Index

curves.

d e s c r i b e d were

and LHT240 w i t h

1,270g m o l

properties

concomitant increases

A second

2:2:1

in

flexural

differ-

variations

(6-8).

toughness,

Figure

produce

fina

blends to

of

profile

polyme

p r o d u c e s RIM

contents

HB

the

to

and excess

System

stress-strain

Changing the

from 8:2:1

the

(971)

tempera-

thermal

tensile

combination of

and 6 of

PU1478 m a t e r i a l s

investigated.

of

the

with

5

blendPBA1478.

patible

are

under 4,

morphologies The

This

together the

as

on

workers

and complex

PU m a t e r i a l s

compensated by

curves

separation

bility

is

shown

mass,

excess p o l y o l

measured v a l u e s

areas

been

effect

visible

significant

A variable

has

the

the

clearly

shown b y o t h e r

r e a c t i o n causes mould.

of

Generally,

and s t r e n g t h .

these

EG

with

As

and molar

shows

elongation

integrated

polyol

PUs

1141). in

reflected

in

also

PUs.

centre

morphological structure Table

PU

RIM

ences

in

RIM

in

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

HB

are triol

BARKSBY ET AL.

Structure-Property Relationships in RIM Polyurethanes

40i

0 20 40 60 80 100 120 140 160 Strain, 7. F i g u r e 3 . T e n s i l e s t r e s s - s t r a i n c u r v e s (23°C) of RIM PUs defined i n Table I . PUs formed from i s o c y a n a t e VM10 and (a) c o m p a t i b l e and i n c o m p a t i b l e p o l y o l blends ( S e r i e s I I ) ; (b) i n c o m p a t i b l e p o l y o l b l e n d s and s l u r r i e s based on PBA1478 (Series I ) .

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

REACTION INJECTION M O L D I N G

Temperature, *C Figure 4. V a r i a t i o n of f l e x u r a l modulus w i t h temperature ( - 3 0 ° C t o 65°C) f o r the RIM PUs i n S e r i e s I and I I d e f i n e d i n Table I . Curves show the e f f e c t s on f l e x u r a l modulus-tempera­ t u r e b e h a v i o u r and - 3 0 / 6 5 ° C r a t i o s of p o l y o l c o m p o s i t i o n and added f i l l e r s , (a) P o l y o l b l e n d c o m p a t i b i l i t y / i n c o m p a t i b i l i t y : Key: Δ , PU221; A , PU421; • , PU521; O, PU621; · , PU821; Θ , PU401. (b) R e a c t a n t r a t i o (System Index) and g l a s s - f i b r e : Key: 1, PU1478-H18; 2, PU1478-C5; 3 , PU401; 4, PU1478-114I; 5, PU1478-104I; 6, PU1478-97I. (PU401 and a l l PU1478 m e t e r i a l s formed from i n c o m p a t i b l e p o l y o l b l e n d s . )

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

6.

BARKSBY ET AL. content PUs of

significantly

reduces the temperature

as i n d i c a t e d by the d e c r e a s i n g v a l u e flexural

son of shows

moduli

at

-30 and 65°C

PU221 w i t h PU401 that

93

Structure-Property Relationships in RIM Polyurethanes

despite

at

dependence

(50.0 to

(Figure

8.8)

4(a)).

approximately equal

of

these

for

the

However,

HB-content

the domination by c r o s s l i n k i n g

of

the

ratio

compari-

(53-59%) absolute

Table I V . T e n s i l e P r o p e r t i e s ( 2 3 °C) o f RIM PUs Formed as 3mm Plaques U s i n g E i t h e r Compatible ( c ) P o l y o l s o r I n c o m p a t i b l e ( i ) P o l y o l s

^ ^ ^ ^ ^ ^ ^

Material

Property

PU821 PU621

^ - ^ ^ ^

Modulus(MN m

- 2

(c)

)

Yield

Strain(%)

values

of is

464

818

1280

325

222

24

35

38

26

24

23

33

10

13

27

24

-

ration

m"^)

flexural

This

modulus

-

23

modulus,

on temperature

flexural

-

17

observed.

23

a "flatter

indicates

temperature

1 1

the effects

dependent p r o p e r t i e s

(-30/65°C)

ratio

of

4.3

uli

from t o r s i o n (G',T)

and loss

respectively. crosslinking

ration

Generally,

having higher state

investigated slightly

in

shows hard

(-180 that

shows The

a distinct contrast, show

so t h a t

two

peaks

PU821

the G , T

a more

the e f f e c t

PU621

On t h e o t h e r

1

into

three

soft

behaviour types.

phase Tg at

PU221

of

to-rubbery

a broader Tg

is

state

is

about

material

behaviour at

PU401

is

to p l a t e a u whereas

densities

6

obser-

temperatures

crosslink

in G

to

divides

i n PU221

80°C r e s u l t i n g PU m o i e t i e s

melt. the showing

125°C.

a n d PU421 For

observed between -30 and 70°C

By

which

from extensive

present.

PU221 for

1

c l e a r l y phase separated

apparent

attributable

occurs

rubbery

between s o f t and

begins

is

range

differ

higher

PU401

-

but d i s t i n c t

Figure

5

sepa-

to

as the hard phase begins

the various

(0°C and 40°C)

phase

temperature

However,

in

mod-

5 and 6

and PU421,

of

hand,

der-

Figure

a n d PU821

transitional

shown

PU221.

increasing

in

-60°C and a hard phase Tg at

no phase s e p a r a t i o n broad Tg at

Figures

the entire

from g l a s s y -

of

and G

lowest

for

storage

from g l a s s y -

range with a small

gradual

shear

no e v i d e n c e

over

of

sepa-

by the

to PU221,

However,

show

dependence

good phase

curves

f

Materials

a dramatic decrease

respectively,

in

transition

70°C.

apparent

interaction

and PU621,

a r e shown

between -30 and 150°C.

200°C,

a single,

mental

200°C).

around

transitional

materials

a single

the t r a n s i t i o n at

a n d PU421 b e c o m e PU401

to

of

temperatures.

HB-contents,

only

terms

the series shifts

27

28

as e v i d e n c e d

phase s e p a r a t i o n w i t h good m i x i n g

particularly

approaching

in

temperature

evident

distinct phases,

(tano,T)

-

Dynamic p r o p e r t i e s ,

data in

occurring gradually

a narrower

plateau

ved

to higher

and e x h i b i t

rubbery

over

tangent

and HB-content

progressively despite

pendulum (1Hz)

of

-

compared w i t h 8 . 8

Dynamic M e c h a n i c a l - T e m p e r a t u r e B e h a v i o u r . ived

(i)

(i)

22

Elongation(%)

PU401

(c)

221

2

Toughness(MJ

PU1478

P U 2 2 1 PU401

(c)

16

2

Stress(MN m" )

(c)

109

Strength(MN m" ) Yield

PU521 PU421

(c)

seg-

PU821

containing

to phase s e p a r a t i o n between,

T32/75- and LHT240-dominated

PU s e g m e n t s

in

thse

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

94

REACTION INJECTION MOLDING

F i g u r e 5. The e f f e c t of p o l y o l b l e n d c o m p o s i t i o n on the dynamic s t o r a g e modulus v e r s u s temperature b e h a v i o u r of the u n f i l l e d RIM PUs of S e r i e s I d e f i n e d i n T a b l e I . (Key as i n F i g u r e 4 ( a ) . )

F i g u r e 6. The e f f e c t of p o l y o l b l e n d c o m p o s i t i o n on damping v e r s u s temperature b e h a v i o u r f o r the RIM PUs shown i n F i g u r e 5. (Key as i n F i g u r e 4 ( a ) . )

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

6.

BARKSBY ET AL.

materials.

The

absence

temperatures

above

phase m e l t s ,

whereas

a

result In

of

the

should

PUs.

bility

the

is

the

level) Phase

network

the

advantages of

is

of

the

of

forming

give

Uniform

logical

initial

SB

slurries

in

slurries

increase Despite

the

decrease the As

the

two

for

higher

filler

is

due t o

expected,

the

it

phase-sepa­

relative the

solu­

various

PU

competing development HB

to

segments w i t h gelation

compatible

of

Regarding the

present

polyol

and w e t t i n g

for

of

those

(10).

blends

the

filled-RIM

as is

shown

that use

the

in

result

using

a higher

Table

is

of

of

glass

process­

a direct

lengths of

4(b)

than

ratios

unfilled of

the

of

the

.

The

a much

fibre

w/w).

smaller

materials

is

HMG i n

ob­

lengths

(70um)

the CSG. filled

PUs

temperature

PU1478-C5, cf

higher

C S G (5%

(PU1478-H18

PU1478-1041 a r e h i g h e r

for

(3.3

l o a d i n g of

of

of

are

greater

result

that

be­

properties

The

PU1478-H18, the

moduli

those

less

stress-strain

III.

much s h o r t e r

1.5mm

Figure

modulus

tensile

compared w i t h

flexural

slightly

flexural

in

and d e r i v e d t e n s i l e

loading in

compared w i t h

-30°/65°C of

and of

slurries

columns of

w/w)

the

HMG c o m p a r e d w i t h

PU1478-H18

forming

incompatible blends,

changes 3(b)

e l o n g a t i o n from

temperatures

these

incompatibility

on the

showed t h a t

PU1478-H18

(10%

and PU1478-C5) of

Figure

last

modulus

served which of

in

HMG u s e d

in

for

or

in

However,

(3).

shown

in of

as

Materials

in

loading

hard

decreasing

ai

PU1478 m a t e r i a l s ,

summarised

prior

at

the

an

For

are

linear

dispersed

PU

filled

s t i l l

as

phase s e p a r a t i o n

completely filamentising

uniformly

paper

is

compatibility.

and on the

versus

rapidly

present.

reactants

segments,

Filled-RIM

haviour

damping

a prerequisite

formed,

clearly evident

compatibility

essentially

measurements

following

PUs,

indicate that

compatible

were more e f f e c t i v e to

is

increases

crosslinking

polyol

not

on g l a s s - f i b r e

-fibres

PU401

s e p a r a t i o n depends m a i n l y

weights

the

studies

in

damping

other

results

subsequently

molecular

LHT240

i n f l u e n c e d by p o l y o l

parameters

moieties

ing.

in

be emphasised that

(on whatever rated

of

180°C where

much h i g h e r

summary,

s e g m e n t e d PUs

95

Structure-Property Relationships in RIM Polyurethanes

as

4.3),

which

the

former.

at

all

dependence

d e f i n e d by again

is

the

the

Literature Cited 1.

2. 3. 4. 5. 6.

Stanford, J . L . ; Still, R.H.; Stepto, R.F.T. In "Reaction Injection Molding and Fast Polymerization Reactions"; Kresta, J . E . , Ed.; POLYMER SCIENCE AND TECHNOLOGY SERIES Vol. 18, p.31; Plenum, 1982. "Technical Data Sheet PU15", ICI Polyurethanes Group, ICI Europa, Belgium. Cross, M.M.; Kaye, Α.; Stanford, J . L . ; Stepto, R.F.T. Following Fruzzetti, R.E.; Hogan, J.M.; Murray, F . J . ; White, J.R. SAE Technical Paper Series, No. 770839, September 1977, Detroit. Schneider, F.W. In "Reaction Injection Molding and Fast Polymerization Reactions"; Kresta, J . E . , Ed.; POLYMER SCIENCE AND TECHNOLOGY SERIES Vol. 18, p.243; Plenum, 1982. Tirrell, M.V.; Lee, L . J . ; Macosko, C.W.; ACS SYMPOSIUM SERIES No. 104, American Chemical Society 1979; p.149.

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

96 7. 8. 9. 10.

REACTION INJECTION MOLDING

Fridman, I.R.; Thomas, E.L.; Lee, L . J . ; Macosko, C.W. Polymer 1980, 21,393. Carmargo, R.E.; Macosko, C.W.; Tirrell, M.V.; Wellinghoff, S.T. Polym.Eng.Sci. 1982, 22, 719. Stanford, J . L . ; Stepto, R.F.T. Br.Polymer J . 1977, 9, 124. Manzione, L.T.; Gillham, J.K.; McPherson, C.A. J.Appl.Polym.Sci. 1981, 26, 889.

RECEIVED April 16, 1984

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

7 Rheology of Polyols and Polyol Slurries for Use in Reinforced RIM 1

2

1

1

M. M.CROSS ,A.KAYE ,J. L.STANFORD ,and R. F. T. STEPTO 1

Department of Polymer Science and Technology, University of Manchester, Institute of Science and Technology, Manchester,M6O1QD, England Department of Mathematics, University of Manchester, Institute of Science and Technology, Manchester,M6O1QD, England

2

Measurements with strate that fibre factor in relation both to attainable fibre loading and to slurry rheology. The fibre packing fraction, Φo, measured by sedimentation, is shown to be a rapidly decreasing function of weight average l/d. For fibres of different l/d the relative viscosity of the slurry at low rates of shear is a unique function of Φ/Φo, where Φ is the fibre volume fraction. The rheo­ logical investigation is based on novel instrumentation and techniques for measuring the viscosity of glass fibre slurries at shear rates from 1 to 10 s . Measure­ ments up to 10 s are based on modified cone and plate geometry, while the higher shear rates are attained with a capillary viscometer attached to a RRIM machine. Measurements on polyol blends with the RRIM viscometer show a slight fall in viscosity as the shear rate is increased to 10 s , but beyond this point there is a sharp rise in viscosity which is thought to be associated with boundary layer effects. 6

4

5

In

t h e RRIM p r o c e s s the i n i t i a l

dispersion

of

into

the mould.

This

for

of

flow.

of In

glass

tively fibre

little length

practical fibre

the

of

rheology has been

difficulties

involved

fibre

to

under

spherical

widely

particles

cylindrical

d.

One r e a s o n

associated with

the

studied

particles for

every

this

conditions behaviour

but or

stage flow

rheological

differing

the packing

have been e x t e n s i v e l y done f o r

at

the f i n a l

a sound knowledge o f

slurries

and diameter

I

is

reinforcing

compara­ fibres,

of

may b e t h e

r h e o l o g i c a l measurements

on

slurries. In

take

calls

fibre

the case

and d i s p e r s i o n

-1

rheological behaviour

from

properties

-1

-1

the present

a systematic viscosity

of

a glass

to

identify

in

a preceding paper

aspects

of

investigation

investigation

t h e more

fibre

important in

this

it

of

has not been p o s s i b l e

a l l

slurry,

the variables but an attempt

parameters.

volume

rheological behaviour

that

(J_) w e r e

have been

to

has been

Polyol

blends

used.

Three

under­

might

affect made

as d e s c r i b e d specific

investigated.

0097-6156/85/0270-0097$06.00/0 © 1985 American Chemical Society

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

98

REACTION INJECTION M O L D I N G 1.

A study

of

the

dependence slurry 2.

3.

relevant

machine,

of

rates

the

in

rate

shear

example,

for φ

of

between

the

For ratios aspect

particles factor

for

is

is

one of

(])

the

and i n

filamentation cylinder.

in

several

noted

v-j

φ

of

were

mono-disperse (2,4) iTd

(v / 2

are

Measurements

the

1.

The

in

reality

be

a rapidly

empirically

φ

a

1/φ Equation

)[1

φ

0

is

results is

2 has

in

care

fibres

the

under

gravity.

medium by hand

taken

to

poured into

by v i g o r o u s

the

but

longer

be r e a c h e d .

w represents slurry,

level

the

the

that

measuring

tapping,

with to

ensure a

sedimentation

If

/(wp^)]"

the

glass

samples

fibres, The was

weight

packing

of

a function are

of

and the

clear

weight

average

basis

from Figure £/d.

and c a n be

w

workers

average

on t h i s

is

essentially

Other

number

represented

(&/d)

polyol.

CSG u s i n g

and i t

of

(1)

1

bimodal blends.

of

uniformly

detailed

relation

of

poor

data.

completely

were

(PB021)

was

was

(100-w)p

with

higher

17um.

dispersed

+

is

sedimentation

equilibrium

and a l s o

that

material

equilibrium

the

aspect

(3).

considerably

work

of

determined

be any comparable

particularly

the

can be

Isham

blends

slurry

densities

function

the

φ

σ

is

in 2

that

seen

represented

equation

ο

a

For

voidage

and by

to

dispersed

assisted

decreasing function by

the

0

different

strand

CSG g r e a t

from

correlation is

0

was

the in

V l

materials

and a c c o r d i n g l y the

(2)

present

volume V2-

c a r r i e d out

have contended

Figure

φ ,

HMG o f

(CSG), where

allowed for

fibre

-

exists

hexagonal close

volume

bulk

polyol

stages,

calculated

σ

there

close packing.

the

appear

the

The

was

final

glass

and

Pg

of

overall

Φ where

fibre

case

the

was

0

of is

determined by

corresponding to

percentage fraction

of

days were

and a l s o

simu­

machine.

fraction

integral

in

complete.

the

s~1, a

distribution

a state

had a diameter

Sedimentation

slow

glass do n o t

the

was

0

the

was

a RRIM

and d a t a f o r

miscible

throughout

A known w e i g h t stirring,

that

and φ

10^

using

a c o n d i t i o n of

(HMG),

air,

Accordingly,

in

CSG u s e d

volume

in

there

important

previously

and

in

packing

strand

occur,

filamentised.

on

1/φ

chopped

ratios

it

became

the

shear

based

represent

measurement

dispersed The

spheres If

is

a RRIM

at

geometry.

to

head,

shape and s i z e

have been p u b l i s h e d by M i l e w s k i

However,

its on

Fraction

c o r r e s p o n d i n g to

σ

study

extending

mixing

in

rheology

and p l a t e

a t t a c h e d to

hammer-milled glass

direct

fibres,

influence

behaviour

This

cone

the

Packing

a defined (φ )

uniform

volume

Here

Fibre

of

in

viscometer

= 0.74.

0

glass

slurry

s~1.

viscometry,

conditions

fraction

packing,

by

r a n g e 0-10^

High

particles

of

and i t s

recirculation

and p o l y o l

with modified

Measurements

bulk

to

polyol

viscometry

capillary

For

dimensions

rheology.

A study,

lating

volume

packing behaviour

on f i b r e

-

1 .38

definite

+ 0.0376U/d) w

implications

1

for

,

(2)

4

the

maximum f i b r e

loadings

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

to

CROSS ET AL.

Rheology of Polyols and Polyol Slurries

O20i

015

0.10

0.051-

(Vd)n 50

100

150

F i g u r e 1. P a c k i n g f r a c t i o n (0 ) of g l a s s f i b r e s as a f u n c t i o n of number average J?/d. K e y : Ο, S o n o d i s p e r s e samples; X , bimodal samples. (The p o l y o l b l e n d used was PB021 ( Ο . 0 : 2 : 1 of p o l y o l s T 3 2 / 7 5 : LHT240: EG. The f i b r e s were CSG of 17 μπι diameter. Bimodal m i x t u r e s were o b t a i n e d by u s i n g p a i r s of monodisperse samples such t h a t the d i f f e r e n c e s between weight and number averages were as l a r g e as p o s s i b l e . )

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

100

REACTION INJECTION M O L D I N G

which £w

c a n be u s e d

=

1.5mm,

fraction 0.45mm gives

in

polyol

give

l/d

= 30

fraction

of

0.339.

would a good

Modified

Cone

Preliminary

gap

cone

setting

both

higher

of

the

using

is

Difficulty sample

the

cone

relative

the

readings

operating

The

cone

fluid. the face

In

of

that

the

'c'

from

be a c h i e v e d ,

longer

equation

cone w i t h

fibres

were

was

plate,

of

of

high

It

rate

the

of

its

also

there

basic

shear

cone

is

test

elsewhere.

to

operate with

cone

apex

In

set

this

at

the

The

programs

have been w r i t t e n

has

been

test

cones.

this

and P l a t e . With

Figure the

The 3

with

the

work

truncated

the

torque

reason

the

truncation

geometry,

of

cone the

cone

there

over

kept

the

small.

large is

gaps

no

Accordingly and

used

a new

involve are

to

is

ω.

such

be p u b ­

a function

of

Computer The

which

analysis

can be

re­

angle. annular

a comparison of

developed is

does not

zero

to sur­

viscosity/shear

analyse data.

concept

shows

with

to

plate

system

there

measured torque

and used

test

set

the

difficult

velocity

plate

the

a displaced

sample.

present

angular

parallel

a d i s p l a c e d cone

associated for

a p p l i e d to

be new.

the

and

way r e l a t i v e l y

regarding

fluid.

c and i t s

large

a displacement

disadvantage that

within

Essentially,

displacement

not

normally

possible

b a s i c assumptions the

of

the

modifications

contact with

r h e o l o g i c a l d a t a becomes more

of

rotate

speeds

cone

in

the

with

balls

within

is

plate.

shear

the

of

mathematical analysis

annular

and

place,

low

Two

apex

the

is

take

advantage of

rate

condition

where with

of

The

the

Cone

for

with

adopted.

of

to

pip

to

w h i c h was

Details

Annular

and

The

be a s s o c i a t e d w i t h

assumptions.

thought

cone

resembling

problem which

The

a

plate

relatively

clumps

and p l a t e ,

a uniform

this

is

i.e.

but

cone

the

suspended p a r t i c l e s .

and P l a t e . meet

at

into

the

as

using

using

aspect ratio

did

to

garded

slurries

impossible

rotation

seemed t o

geometry were

to

often

Shearing

forming

the

provides

involves

also

also

a central

movement o f

also

and when

erratic.

position

a uniform

cone

to

and

mono-

encountered

approach

lished

2

for

cones.

mathematical

the

(2)

fibre

and p a r t i c l e

vertical It

it

surface

characteristics

to

fibres

size

computation of

normally

with

difficulties

plate.

can the

in

system,

the

weight

length

= 0.0173

0

rheogoniometer

difficulties

gap between the

the

order

cone/plate

the

very

These

theoretical

on g l a s s

a truncated

Serious

and p l a t e

is

that

φ

Milewski

a

fibre

and a F e r r a n t i - S h i r l e y

standard

position.

D i s p l a c e d Cone

geometry

the

experience

to

were

narrow the

in

resulted

wool.

geometry,

resistance

test

cotton

attempted

particularly

was

the

of

d a t a of

(e.g. to

concentrations

high

compared w i t h

=100

w

same d i a m e t e r ) ,

may b e n o t e d the

U/d)

corresponding

Reducing

a Weissenberg

essentially

fibre

sometimes

It

both

purposes.

very

the

of

were

and p l a t e

instruments,

at

stream.

(for

instruments,

viscometer

particle

with

= 0.0398,

0

Viscometry

measurements

cone

a fibre

φ

rods.

and P l a t e

laboratory

truncated

the

representation

wooden

plate

Thus

0.092

disperse

two

RRIM.

gives

of

a weight

in

d = 0.015mm)

is

a small

flat In

cone

is

truncated

error

surface, turn,

and and

this

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

imposes

7.

CROSS ET AL.

Rheology of Polyols and Polyol Slurries

Figure 3.

T r u n c a t e d and a n n u l a r

cones.

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

101

102 a

REACTION INJECTION MOLDING limit

to

normally

the

in

With

attainable

the

the

range

annular

whole

of

the

radii

a]

and a2-

a2,

and the

ches The

unity

torque

the

τ

gap w i d t h , to

cone

is

there

σ is

the

=

shear

the

the

viscosity,

1 a

for

cone,

the

η,

The

conventional of

and the

difficulties

were

to

represent

using

adopted the

largely

a

non-Newtonian

for

wide

and w i t h of

flow

curves

in

for

PBA1478,

This

is

different

(see

to

be

subsequent

employed,

although

fibre

fibres.

slurries

concentration.

found

all

gaps

overcome,

longer

new

checked by c o m p a r i -

A g r e e m e n t was

were With

was

fibre

were

polyols

sition

and v i s c o s i t y , molar

and

mass

11.3

CO)

exhibited

slight increase

illustrated w/w

in a

in

Figure

concentrations

measured w i t h

Figure

5

At

the

a given

a plot

against

volume

lengths

suspended i n

the

relative

only

apply if Figure

slurry

viscosity,

dotted

vertical

different

fibre

5

in

both

viscosity

of

3°

the is

two

the

fibres the

and a l s o

the

indicate

lengths

are

major

and i t

is

was

no

the

of

CSG o f

should

Again there to

the

of

of

different

is

evidence

be emphasised t h a t of

fibre

packing

experimental seen t h a t ,

media.

rate

precise nature

a well-defined

influence

in

a

signifi-

two

slurries

influence the

of

zero

polyols.

in

there

other

respectively

at

insensitive

two compo-

b l e n d and the

viscosity

for

it

in

chemical

25°C b e i n g

viscosities

relative

However,

shows

lines

of

at

concentration

relative

concentration,

suspending medium.

sion.

viscosities

between the

shows

70um HMG d i s p e r s e d

significantly

one b e i n g a d i o l / t r i o l

triol,

Poise.

differences

measured using

differing

higher

will

angular

cone.

different

the

cone measurements

validity

became more marked w i t h

Viscosities

that

3°

and'fitted

glass

a series

fibre

aluminium

which

CSG d i s p e r s e d

shear

A prototype in

the

1.5mm,

1.4

made

behaviour,

4 with

cant

(3)

(4)

decalin.

slurries.

general,

length

annular

in

remained a problem with

fibre

. = σΑ

2

(5)

1100um was

new t e c h n i q u e s

on f i b r e

In

2. a )

total

= ω/α

c o n e / p l a t e geometry

experimental

thinning

by

-

of

configuration.

and the

given

,2

value approa­

= ατ/(ωΑ)

polyisobutylene

shear

is

the

a-|/a2

and p l a t e

the

bounded by

Also

and t h e i r

measurements

Results.

to

As

maintained

surface

and a n n u l a r

techniques

solution

clumping

limitation

a ring

is

since

surface

viscometer.

son w i t h

excellent,

no

cone/plate system.

d i s p l a c e d cone

expérimental

is

error

conical

2j 2πσ da = - y -

= ω/tana

a gap w i d t h o f

a Ferranti-Shirley

are

i

conventional

with

Gap w i d t h s

2

stress.

η as

a.

comparable the

to

rate

conical r 3

2πσ

γ and

there

shear

a

where

no

over

approximates

over

τ

is

developed

uniform

developed

tan

can be c o m p a r a t i v e l y l a r g e .

system of

a2

100Mm.

Consequently

gap w i d t h

condition

torque

10

state

of

disper-

aspect ratio behaviour.

values each

of

this

of

case,

φ

0

the

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

for

on

The the

CROSS ET AL.

Rheology of Polyols and Polyol Slurries

F i g u r e 4. Flow curves f o r 1.5mm CSG d i s p e r s e d i n PBA1478. (1) f o r s p e c i f i c a t i o n of p o l y o l b l e n d PBA1478.

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

See

REACTION INJECTION M O L D I N G

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

7.

viscosity approach The by

is

rising

to

a s y m p t o t i c a l l y as

conditions

viscosity

replotting

viscosity

at

n

zero

of

data

as

r

k

is

ised

called

derived

from

gives

volume f a c t o r

kφ

=

0

1,

shows

accordance

against

in

large

against the

curves

Equation

of

7

and p l a t e

viscometers ,

2 χ

The

are

essential,

mixing

1/4 in

could of

head

of

employed

inch outer inner

be r a p i d l y

narrow

highest bore

an epoxy

fittings mounted

was at

The

linear­

values of

of

the

φ

0

linear

equates with

superposed and of

relative

the

linearised

fluidity

usual

s~1

to

is

liquid

the

cylindrical vessel, of but

in

diameters

psi

emerging from

order

with

5 χ

to

head.

tubing,

the

the

drop

minimise

b a f f l e d by a d i v e r s i o n

inch

In

a float

were used

to

for

measure in

where

to

entered

the of

centre the

in

tube.

collected

Liquid

6 horizontal

were

diameter,

connected

in

tube

and hence

order

in

range length

Swagelok

transducers these

the at

The

i.d.

inch

a l o n g the

any i r r e g u l a r i t i e s

through

inch

RRIM m a c h i n e ,

tube

1/4

s"^ .

1/4

c a p i l l a r y was

a vertical

requirements

a 3/16 the

of

on

cementing a short

a p p r o x i m a t e l y 35cms

through

use

selected

10-*

pressure

pressure

for

was

lengths.

available

was

displacement transducer.

cylinder

were

c a p i l l a r y and n o r m a l l y rate

of

it

the

steel

thickness

inside

was m e a s u r e d b y m e a n s o f

a linear

much

region

in

suitable

a p p r o x i m a t e l y 500cm^ s ~ 1 .

the

collecting

to

expedient of

0-5000

is

viscometer

stainless

rate

tubing

rate where

interchangeable capillaries

and w a l l

r e c o r d the

large

level

is

the

Accordingly, rate

Compatability with

volume flow

viscometer,

limit in

conditions

and cut

However,

the

retained.

mode

shear

(o.d.)

shear

inch o.d.

end of

rates

shear

slurries,

practical

of

internal

rates

by

adhesive.

thus

a high

(i.d.)

attainable

3/16

attainable

and c o n v e n i e n t l y i n t e r c h a n g e d by the

this,

was

the

glass-fibre

simulating

diameter

shear

1θ6

each

differential

base

relation and

CSG c a n b e

gradient

a RRIM m a c h i n e .

operating pressures.

the

extended to

ture

5

shear

a series

diameter

attainable

high

liquid

(5)

to

highest the

estimated

i n c h Swagelok f i t t i n g s ,

the

The

viscosity

with

with

a RRIM m a c h i n e ,

viscometer

on

a

compares

for

differing

using

for

using

a plot

the

but

d e s i g n and c o n s t r u c t

attachment

of

-φ)

0

Figure

s"*',

to

decided

was

A

0

viscosity.

data

reduces

1

the

tubing

φ/φ ·

(6)

(φ

with

in

the

curve

relative

RRIM V i s c o m e t e r

region of

s-1

basis

of

the

°

the

6

a single

that

-

r

10

1/4

an

gives

intrinsic

This

These

function

intrinsic

6

log

Equation

four

gap d i m e n s i o n s

based

(6), Μ >

to

d e r i v e d by Mooney

σ

lower. 6

with

σ

cone

the

the with

i.e.

0

φ/φ .

High-Shear With

a unique

Equation

i.e.

n 6

is

and φ/φ »

dimensionless

and

φ ,

indicating

0

0

r

to

c a n be reduced

φ/φ >

sedimentation measurements.

plot

in

5

of

= [1-Φ/Φ Γ

with

log n

bulk

Figure

rate

r

the

conformity

by p l o t t i n g

Figure

and Dougherty

n

In

of

viscosity

m o d i f i e d , by K r i e g e r

φ tends

maximum p a c k i n g .

a function

shear

between d i s p e r s i o n

where

105

Rheology of Polyols and Polyol Slurries

CROSS ET AL.

a

the

the

arma­

the of

the

surface

it

channels arranged

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

REACTION INJECTION M O L D I N G

106

radially of

at 60° angular

spacings

in a cylindrical

By

connecting the output

recorder, is

the rate

the radius

of

of rise

Also,

if

Newtonian

ÏÏR

at the base

is

If

Ρ is

the pressure η of

η The

capillary

the appropriate

d^

of

the tube d2

Viscous order was

heating

walls

is

perfectly are

is

=

3

r,

(8) the shear

2

along is

4

a micrometer

or more,

that

Correction.

and shear

t h e measurements

i n the c a p i l l a r y . both

andalso

adiabatic,

In it

for the other

the f i r s t

fluid

viscosity first

these

conditions

where

ρ and s are the density mean t e m p e r a t u r e

response

rise

were

throughput

(height)

recorded, is

on the plateau

the volume-time This

shows

similarity is

was a l s o

gradient

indicated

drop,

7.

region,

where

Ρ is

which

Equation

a specific

11

measure

three

t h e volume recording

The pressure

pulse

calculations essentially

is

were constant

.

f o r Ρ andΤ

relation

plot

is

between

Conformity

on a polyol

a linear heat

of

of the

linearity.

the theoretical

gave

side

A typical

andv i s c o s i t y

shown b y measurements

capillaries,

Under given by

was r e c o r d e d b y means

rise.

corresponding with

is

liquid.

For each v i s c o s i t y

i n Figure

i n form,

for adiabatic conditions

equation

the liquid

i n the form of the pulses

consistent

result

(7).

on the output

the pressure

shown

usually

This

heat of the

the liquid

10°C.

P,

such as

U l )

and the temperature

andvolume

rectangular

A basic

of

namely

approximately based

of

heat drop,

P/(ps)

and s p e c i f i c

a n d c o u l d b e up t o

pressure

rise

chrome 1-alumel t h e r m o c o u p l e

quantities

The

-

dimensions.

of

conditions

variables

by Jakobsen and Winer

t h e mean t e m p e r a t u r e ΔΤ

where

the total

of other

through

case

on the pressure

and c a p i l l a r y noted

treated

conduction

situation,

it

influenced by

limiting

c a n b e shown t h a t

rate,

t o have been

heat

of the

as 1 0 ° s"^,

The problem has been

shear

different

internal

be greatly

f o r t h e s i t u a t i o n where

independent

Τ

and the

as high

would

and i s

and

9

With v i s c o s i t i e s

rates

the c a p i l l a r y ,

found.

the

Z

equation

wer

along

and

length

stainles

depends only

for

of

(10)

volume

capillary

wall,

(9)

by the P o i s e u i l l e

per unit

The

at the

2

negligible,

essentially

fast

rate

3

the capillary

given

conducting walls.

dissipation

appears

R

rate,

( 4 R / r ) dh/dt

andTemperature

10 P o i s e

mathematically, the

flow

given by

was m e a s u r e d w i t h

anticipated

viscous

andQ t h e volume

to a pen

and,if

calculated.

Heating

of

vessel

transducer

was o b t a i n e d ,

= r P/(8R Adh/dt)

diameters

of

diameter

drop

the f l u i d

π

(dh/dt)

dh/dt

2

radius

flow,

y = 4(}/

viscosity

liquid

the c o l l e c t i n g

the c a p i l l a r y

assuming

of the displacement

of

Q =

a

block

the vessel.

with

Ρ

this

b l e n d w i t h two

of ΔΤ against

of 0.45 c a l g " ^ ,

in

P.

resonable

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

7.

CROSS ET AL.

Rheology of Polyols and Polyol Slurries

τ

1

1

1

1

1

0

5

10

15

20

107

r

TIME ( S E C O N D S )

F i g u r e 7. T y p i c a l RRIM v i s c o m e t e r t r a c e s f o r p r e s s u r e and volume throughout.

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

REACTION INJECTION MOLDING

108 agreement

with

conventional

an e x p e r i m e n t a l v a l u e

method based

on the

of

0.50

mixing

of

cal g"

liquids

o b t a i n e d by

1

at

a

different

temperatures. The

viscometer

employing

supplementing range

of

the

The up

could

pressures the

in

high

shear

from a s e r i e s

at

a known r a t e

Ύ]

and T2.

of of

was

rate

be used

r a n g e 0-50

shear

viscometer

high

also

the

rate from

shear

10

to

2

viscosity

and at

lower

known

p r o c e d u r e was

this

10

input

for

It

ranges

involved,

the

showed a l i n e a r

temperature obtained

capillaries, shear

rates

viscometer two

reduced up

to

are

is

rate

a very

unexpected

shows

this

way t o

temperatures

over

the

temperature that

data for

conditions

at

the

a temperature

dependence mean

a polyol

and w i t h of

a

limited

blend,

different

25°C.

Data

for

10

included fo show

thinning.

a shear

there

in χ

2

8

temperature

built

obtained

reducing data to

assumed t h a t ,

correspondended to Figure

different

instruments

shear to

+ T^)/!.

(Tj

under

By

were

each

and output

temperature. viscosity

by

operating

viscometer

reference

t h a t the measured v a l u e

way t h e

data points,

single and

rates

s~^.

6

the

adopoted was

shear

from a compressor.

data in

data obtained in

individual

A simple

at psi

In of

r e a s o n a b l e agreement and b o t h the

RRIM v i s c o m e t e r

approximately 3 χ

sharp

rise

and r e q u i r e s

associated with

in

10^

this s~^,

but

apparent v i s c o s i t y .

further

boundary l a y e r

show

behaviour

investigation

but

evidence is

beyond This is

of

maintained this

point

rise

is

thought

to

quite be

effects.

Acknowledgments Financial

support

by

the

Science

and E n g i n e e r i n g

We a l s o

thank

some o f

the

Turner

Imperial

polyols

Brothers

Polymer

Engineering

Research Council Chemical

Industries,

used and P i l k i n g t o n s

Asbestos

Ltd.,

is

for

Directorate gratefully

the

Organics Division

Fibre

supplies

of

acknowledge.

of

Glass glass

Division fibre.

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

for and

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

Figure 8. V i s c o s i t y (η) versus shear rate (γ) for PB521 at 25 °C. , RRIM viscometer; data corrected to 25 °C as described i n text. , cone and plate viscometer data. See (1^) for speci­ f i c a t i o n of polyol blend PB521.

η

s

I

I ?

Î

!

>

C/3

ΙΑ

ο

110

REACTION INJECTION M O L D I N G

Literature Cited 1. Barksby, N.J.; Dunn, D.: Kaye, Α.; Stanford, J . L . . ; Stepto, R.F.T., preceding paper. 2. Milewski, J.V. Reinforced Plastics/Composites Institute Soc. Plastics Ind., Inc., Proc. 28th Annual Tech.Conf. 1973, Section 31, pp 1-8. 3. Isham, A.B., Reinforced Plastics/Composites Institute, Soc. Plastics Ind., Inc., Proc. 33rd Annual Tech. Conf. 1978, 14-A. 4. Tucker, C.L.; Suh, N.P. Polymer Engg. and Sci. 1980, 20, 887. 5. Mooney, M.J. J . Colloid Sci. 1951, 6, 162. 6. Krieger, I.M.; Dougherty, T.J. Trans.Soc.Rheol. 1959, 3, 137. 7. Jakobsen, J.; Winer, W.O. Trans.Amer.Soc.Mech.Eng., Series F, J. Lubrication Technol. 1975, 97, 472. RECEIVED

April

16, 1984

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

8 Organotin Catalysis in Urethane Systems K. WONGKAMOLSESH and JIRI E. KRESTA Polymer Institute, University of Detroit, Detroit, MI 48221 The catalysis of urethane formation reaction by dibutyltin dilaurate (DBTDL) was investigated in the model system isocyanate-n-butanol. It was determined that DBTDL participated in the polarization of the isocyanate group durin th catalysis O th othe hand the amine catalys not polarize the isocyanat group catalytic activity was associated with the induced polarization of the hydroxyl group. During the interaction of alcohol with DBTDL no ligand exchange was detectable, but solvation of the tin central ion and separation of the carboxylate amine by the hydroxyl group was observed. The mechanism of DBTDL catalysis based on the interaction of isocyanate with the solvated tin complex is discussed. The effect of a small amount of the hydrolyzable chlorine on the urethane formation reaction, catalyzed by DBTDL was studied. Catalysis

plays

Catalysts

not only

an important affect

morphology and ultimate In

the urethane

RIM

role

the

in

curing

properties

technology,

t h e RIM p r o c e s s i n g o f characteristics

of

but

r e s u l t i n g urethane

the catalysts

most

urethanes.

also elastomers.

often

used are

organotin

compounds.

Many i n v e s t i g a t o r s

studied

the mechanisms

catalysis

of

r e a c t i o n and t h e i r

results

were

in

several

urethane

reviews

2*

(1,

urethane

of

complexes

between o r g a n o t i n

complexes

between t i n

complexes

were

organotin

and p r o t i c

and

i s o c y a n a t e s was n o t

shifts (8)

f

in

found

forming

16). IR

(1-20).

The complex

_4

accepted

and r e a c t a n t s The

reactants

formation

observed.

of

established,

proposed mechanism i n which

in

of

the

triple

complexes between

was e x p e r i m e n t a l l y

Bloodworth

the

Various

between o r g a n o t i n

and r e g e n e r a t e d o r i g i n a l

that

the formation

including

formation

verified

catalysts

because

and Davis

t r i a l k y l t i n methoxide reacted with

formed urethane they

is

and reactants.

t r i a l k y l s t a n n y l carbamates which

results,

it

associated with

satisfactorily

s p e c t r a were

that

is

catalysts

catalysts

proposed

catalysts

15_

reaction

(3,

f

Generally,

17).

catalysis

of

summarized

no

et a l .

isocyanate

the presence of

catalyst. the l i g a n d

Based on

alcohol these

exchange

0097-6156/85/0270-0111$06.00/0 © 1985 American Chemical Society

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

REACTION INJECTION MOLDING

112 b e t w e e n DBTDL a n d a l c o h o l o c c u r r e d f o r m i n g main

The

kinetic

b y DBTDL explain series

this of

complex

that

of

alkoxide

19)

isocyanate-alcohol reactions

dependence

DBTDL was

behavior

(18,

of

the

not

various

consecutive

catalyst

as

of

the

linear

rate

(14,

18,

complexing equilibrium

or

20).

mechanisms were

dissociation

of

catalyzed

constants In

on

the

order

to

proposed based (14),

on

dissociation

OH b o n d i n

the

of

alcohol-DBTDL

(20).

At mental

studies

showed

concentration

a

organotin

catalyst.

the

present

d a t a on

time,

the

tin

regardless

catalysis,

of

the

a great

quantity

mechanism i s

of

s t i l l

experi­

not

fully

understood. In

this

paper,

between v a r i o u s solvation on

the

at

the

results

catalysts

the

tin

catalytic

dealing with

and i s o c y a n a t e s ,

cation,

activity

of

the

the

complex

ligand

and e f f e c t

of

DBTDL w i l l

be p r e s e n t e d

formation

exchange and

hydrolyzable

chlorine

and

discussed.

Experimental Dibutyltin octane

dilaurate

(Air

carbamoyl

chloride

c y a n a t e were nate,

acetate

purified The

(0.5N)

were

25°C. The

meter,

(Eastman

carried The

out

samples

contents

IR

in

reaction

Aldrich

before

flask taken

Chem.

Co.),

at

diiso­ isocya­

2-

(Mallinkrodt)

use. (0.5N)

with

three-necked flasks

was

and

p-tolyl

and n - b u t a n o l

isocyanates ml

[2,2,2.].

(IEM)

and hexamethylene

isocyanate*

immersed regular using

recorded using

The

in

a

time

the

n-butanol

under

nitrogen

thermostated intervals

Pye-Unicam

bath

and

dibutylamine

the

method.

spectrophoto­

conductivity

of

using Leed & Northrup

conductivity

bridge

catalyst and

systems cell.

Discussion

Interaction

Between

NCO G r o u p s

reactivity

of

isocyanates

determined

by

the

density

the

dipole moments; charges

(all

1,4-diaza

specific

and

in

Co.)

Kodak C o . ) of

Co.),

methacrylate

Phenyl

determined

s p e c t r a were

studied

Chem.

Chem.

300

were

were

model 3-300.

Results

the

(Dow

by d i s t i l l a t i o n

The

isocyanate

was

IEM

supplied.

catalyzed reactions

atmosphere. at

of

used as

(M & Τ

isocyanatoethyl

ρ-chlorophenyl isocyanate

ethoxyethyl were

(DBTDL)

Products),

in

structure

urethane

and the

the

nitrogen

density

Catalyst.

formation

distribution

isocyanate molecule.

and carbon c a r r i e s

electron

and Organotin

the

The

a positive

of

the

isocyanates

and oxygen c a r r y the

The

is

electron

possess

fractional

charge.

can be d e p i c t e d by

The

reaction

large

negative

distribution

following

of

resonance

formulas:

- +

+-

R-N-C«£The by

size the

of

withdrawing partial

fractional

substituent

R

charges

in

substituents

positive the

>• R-N=C=0 —

the

in

increased

reactivity

the

a t t a c h e d to

charge on

resulting

of

vicinity the

*

i s o c y a n a t e group of the

the

isocyanate with

NCO g r o u p of the

is

NCO g r o u p .

carbon atom of

increased polarization of

R-N=C-Ô|

the

the

increase

electron the

NCO g r o u p ,

NCO g r o u p

protic

determined

The

and

reactants.

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

On

8.

WONGKAMOLSESH AND KRESTA

113

Organotin Catalysis

the other hand, the electron donating substituents decrease a p a r t i a l positive charge on the carbon atom and with the decreased p o l a r i z a t i o n of the NCO group, the r e a c t i v i t y of isocyanate i s decreased. These facts explain the differences i n r e a c t i v i t i e s between aromatic and a l i p h a t i c isocyanates i n the urethane formation reaction. For the non-catalyzed urethane reactions i t was established (23) that the r e l a t i v e r e a c t i v i t i e s (ratios of rate constants) of substituted aromatic isocyanates correlated with the s t r u c t u r a l parameter σ of the substituent R (measuring the electron withdrawing a b i l i t y of the substituent R) according to the Hammett equation: log

τ— κ

=

ο

σ ρ

where k and k are rate constants for the non-catalyzed reaction of substituted and non-substituted isocyanates. The positive value for ρ (determined by variou electron withdrawing group p o l a r i z a t i o n of the isocyanate group. As was mentioned previously, the catalysts accelerate the urethane reaction by the induced p o l a r i z a t i o n of reactants i n the t r a n s i t i o n complex. The formation of polarized complexes between the NCO groups and catalysts (amines, organotins) was not s a t i s f a c ­ t o r i l y documented. Indirectly, the formation of polarized NCOcatalyst complexes i n urethane reaction can be established by study­ ing the dependence of the rate constants on the substitution of phenyl isocyanates i n the presence of various catalysts. The magnitude of the reaction constant Ρ i s e s s e n t i a l l y a measure of the p o l a r i z a t i o n of isocyanate groups induced by a c a t a l y s t . In the case that the catalyst polarizes the NCO group during the reaction, the contribution of the substituent R on the benzene ring to the p o l a r i z a t i o n of the NCO group w i l l diminish r e s u l t i n g i n the decrease of the p-value. In the opposite case, there w i l l be a small e f f e c t of the catalyst on the p-value. The data for noncatalyzed and catalyzed urethane reaction by 1,4 diaza [2,2,23 octane (DAO) and DBTDL are summarized i n Table I and Figure 1. Q

TABLE I. Catalyst Isocyanate CI—^^-NCO @-NCO CH -^^-NCO 3

Ρ

σ

Non-Catalyzed log (k /ko) x

log

DAO (k /k ) x

Q

log

DBTDL (k /ko) x

0.23

0.596

0.562

0.094

0

0

0

0

-0.17

-0.373

-0.251

-0.0586

2.45

2.15

0.38

As can be seen from Table I, the p-values for uncatalyzed and DAO catalyzed reactions are r e l a t i v e l y close, indicating that DAO catalyst does not s i g n i f i c a n t l y participate i n the induced p o l a r i z a ­ t i o n of isocyanate.

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

114

REACTION INJECTION MOLDING

These et

results

al.

with

support

(21).

the

The

the

mechanism proposed

reaction

polarized

proceeds v i a

amine-alcohol

previously

interaction

complex

Farfcas

isocyanate

(22):

δ+

δ

Ζ

+ ROH - — » 3N|-~H—OA

~N|

by

of

(I)

^R

I

+

In the

R'NCO

the

case

p-value

also

of

the

(Δρ =2.07)

reported

catalyst

R'

through

δ+

δ+

1-

R'NHCOOR +

δ^

observed.

et

al.

—Ni

R

DBTDL c a t a l y s t , was

by E n t e l i s

participates

δ-

a significant

decrease

A comparable decrease

(13).

This

indicates

that

of

was the

tin

i

complexation

wit

R

δX

δ+

N—C—0 Sn+

Ligand based were

Exchange on

the

proposed

exchange of

the

of

in

DBTDL a n d S o l v a t i o n

i d e a of in

the

the

—Sn

I ' - '

C—R

ligands

hydroxyl

+

In

order

to

better

complexes,

reactants

a n d DBTDL was

DBTDL i s has

with

as

for

alkoxy

(alcohol)

studied

monomeric

in

a bidentate

were

+

the

IR

mechanisms tin

atom

or

an

ionisation

suggested:

R—COOH

catalytic

of

using

a liquid

structure

ligands

I

the

central

those mechanisms

groups

possibility

Several

the

In

—Sn—OR

understand

the

an o c t a h e d r a l

tin

20).

"*—

organotin

It

(8,

R-—OH — — * •

0

Effects.

exchange at

literature

carboxylate

coordinated

ligand

mechanism

ligand

of

exchange

between

spectroscopy.

form as

well

and c a r b o x y l a t e

as

in

groups

solution. are

coordinated

ligands: R

R In v

as

the

IR

spectrum,

(C02)

1600

(dissociated model (molar The

study

the 1

carboxylate

carboxylate

ratios in

1:1:1)

anion

premixed

as

2.

the

case

DBTDL to

in

n-butanol

was

investigated In

of

ligand

separated

with

and urethane

DBTDL was Figure

anions

(bonded b i d e n t a t e

DBTDL was

residual

summarized

cm"

ion

of

IR

by

pairs)·

ligand

In

peaks cm"-l our

isocyanate

acetonitrile.

spectroscopy.

the

two

a n d 1565

and η - b u t y l

extracted

by

showed

tin)

Results

exchange and

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

are the

WONGKAMOLSESH AND KRESTA

Figure

1.

aromatic

Effect

Dependence substituted

of

catalysts with

the rate

on the r e a c t i v i t y

of

substituted

n-butanol.

constant

ratios

on the σ-parameter

of

isocyanates.

A no c a t a l y s t , Solvent:

of

isocyanates

Organotin Catalysis

ο 1,4

Diaza

2-ethoxylethyl

F i g u r e 2. Comparison w i t h a n e a t DBTDL (

[2,2,2]

octane,

·

DBTDL;

Τ

=

25°C

acetate.

o f IR ).

spectra

of

extracted

DBTDL

(

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

)

116

REACTION INJECTION M O L D I N G

formation and of

of

alkoxide,

an increase of these

changes were

extracted

DBTDL

showed t h a t

cm"" indicating the c e n t r a l The

effect 3.

absorption was

This tin

of

2)

with neat

spectra

DBTDL

of

peak None

of

(dotted

DBTDL h a d i n c r e a s e d a b s o r p t i o n

n-butanol

o n t h e IR

the presence of at

line)

band

carbQxylate

spectra of

n-butanol,

1565 c m l a n d a d e c r e a s e

at

anions

DBTDL

is

depicted

an increase

of

the

of

-

indicates

ion.

ligand

site

on the t i n

study

(C0 )

of

of

a band

a t 1600 cm-1

that

solvated

Similar

4.

of

in

ethanol

was o b s e r v e d i n of

urethane

Hydrolyzable small

activity

of

anatoethyl

(no

alcohol or

polyol

in

the presence

a l c o h o l was c o n f i r m e d b y t h e of

lauric

the s p e c i f i c

concentrations acid.

of

is

band a t

DBTDL-lauric

data,

conduc-

a r e shown

in

t h e DBTDL was

This

the absorption

chlorine

isocyanates

of

the chlorine

summarized

in

of

carbamoyl

of

shown

in

Figure

5,

1565 cm-1 ( s o l i d

acid.

the p r o b a b l e mechanism of catalyst

in

is

in

effect

the

depicted

urethane

maximum a t

reaction.

on the change

8.

It

500 ppm o f

chlorine,

in

chloride.

chlorine

chlorine

interaction

It

of

diisocyanate using

the rate that

chloride

was assumed t h a t the interaction

of

DBTDL w i t h

carbamoyl c h l o r i d e

technique.

is small

the form

the rate

of

constant

for

achieving the

decreased.

This

was u s e d

place

understand of

the presence of Results

reactivity measurements

in

effect

of of

the carbamoyl chloride

In

t h e IR

of

the a c t i v a t i o n

catalyst.

(with and without

to

the

constant

and a f t e r

the r e a c t i v i t y

order

system—isocy-

the very

especially in

c a t a l y z e d b y DBTDL

was due t o

t h e DBTDL

of

The

catalytic

decreases the

the beginning

was n o t o b s e r v e d when b e n z o y l

carbamoyl

Catalysts.

on the

The r e s u l t s

was d e t e r m i n e d

increased at

reaction

Tin

The p r e s e n c e o f

isocyanate usually

the hydrolyzable chloride,

of

chlorine

on the model a l i p h a t i c

and n - b u t a n o l .

the urethane

Figure

on A c t i v i t y

hydrolyzable

DBTDL was s t u d i e d

of

this

of

the d i s s o c i a t i o n

Chlorine

amounts

methacrylate

hydrolyzable

studied

it

6 a n d 7.

of

the

group.

isocyanate.

r e a c t i o n b y t h e DBTDL

of

with

in

the system

effect

effect

the

s u c h a s DMF a n d D M S O .

at various

on the presented

Effect

amounts

isocyanate

i s o c y a n a t e s w i t h DBTDL

The dependence

by the presence of

catalysis

the

DBTDL

measurements.

On t h e c o n t r a r y ,

Based Figures

of

isocyanates

o n DBTDL w a s o b s e r v e d i n

solvents

the disappearance of

line)

of

ion

sphere

created a vacant

coordinate

by the hydroxyl

effect

aprotic

DBTDL

inhibited where

group

DBTDL w i t h

form a complex w i t h

dissociation

of

Figure

to

solvation

polar

conductivity tance

the t i n

isocyanate absorptio

to be able

The

to of

no c o o r d i n a t i o n

occurred

other

solvated

the hydroxyl

ion suitable

DBTDL)

order

of

group

from the c o o r d i n a t i o n

the i n t e r a c t i o n

to be f i r s t

2

has

of

the hydroxyl

coordination

determined

shifts

that

the carboxylate anion This

o u r IR

was

of

The c o m p a r i s o n o f

Figure

(CO2)

a

alkoxide.

observed.

separating

In

the v s of

atom.

In

band

of

1

increased separation

1

Figure

be a decrease

1710 c m - a n d v ( C - O )

line,

the extracted

from

will

at

observed.

(solid

1565

in

there

v(C=0)

this

effect,

the

hexamethylene n-butanol)

a r e summarized

was in

Figure

9.

I t was f o u n d t h a t t h e l i g a n d e x c h a n g e o c c u r r e d a n d t h e r a t e o f exchange depended on the p r e s e n c e o f n ^ u t a n o l i n the system.

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

Organotin Catalysis

WONGKAMOLSESH AND KRESTA

F i g u r e 3. Comparison o f the IR s p e c t r a o f the s o l v a t e d DBTDL (DBTDL/n-BuOH - 1:5) ( ) w i t h a neat DBTDL ( ).

J

1

I

2 ΙΟ

3

I

I

3

4

L

5

χ [DBTDL] Ν

F i g u r e 4. Dependence o f the s p e c i f i c conductance o f DBTDL s o l u t i o n i n e t h a n o l on the c o n c e n t r a t i o n o f DBTDL.

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

Figure

5.

Mixture

of

Effect DBTDL

-Cr

lauric

acid

o n IR

spectra of

and l a u r i c

of

acid

(1:1)

(

);

DBTDL.

neat

DBTDL

(

).

Sn' :-C- + R O H - ± —CO* Sn ROH ~

molecule capable

faster

polymerization

With d i i n i t i a t o r s

due to

a branching

commonly-used c a t a l y s t s

for

the

of

rate

c a n b e made b y r e a c t i n g

for

product

a

is

reaction.

caprolactam

polymerization

c a p r o l a c t a m and c a p r o l a c t a m magnesium b r o m i d e .

catalyst

by

c a p r o l a c t a m monomer.

J

given molecular The

forming the

a Grignard

The

reagent

with

caprolactam. The

anionic

polymerization

depth by W i c h t e r l e of

Macromolecular Chemistry

Nylon The

6 Reactive

use

of

directly the

production

viscosity, was

is

anionic

low

Corporation. the

of

lactams

Prague.

has

been explored

co-workers

at

the

in

great

Institute

(6-8)

Molding

initiated

Polymer

feed

in

polymerization

f r o m c a p r o l a c t a m was

the

of

and Sebenda and t h e i r

large

initial

and the

pieces rate

heat

commercialized in

The

of

of

to

c o m m e r c i a l i z e d In t e c h n o l o g y was since

the

increase

United

monomer

viscosity

polymerization is

Germany by B a y e r .

the

particularly

molten of

produce cast

low.

of

shapes States

useful is

of

the

A similar

(9)

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

by for

low

catalyzed system

HEDRICK ET AL.

Nylon 6 RIM

F i g u r e 3 . Use of a n i l i n e to c o n t r o l m o l e c u l a r weight distribution.

and

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

REACTION INJECTION MOLDING

140 The

adaptation of

casting

and r e a c t i o n

undoubtedly here

proceeded at

reports

the

work w i t h which In culate

1962,

low

cost,

forcement

and y i e l d s

to

silicates, to

dry.

Moisture

disrupts

the

properties silanes,

which

is

s t i l l

nylon

plasticized

destroyed In

I960's

products

are

of

which

the into

taining

dispensed

The

the

into

mold. the

the

abrasive

than is

to

best

sale

faces, Methods

I.

The Since

rein-

high

loading

with

In

order For

to

the

are

polymer

system

it

is

silica

is

or

very

and bonds completely

degraded.

Functional

provides While

an

the

effective

nylon

bond between phases

not

maintained. for

RIM

as

molding.

this

several

well The

as

was

before

a

product

properties

of

the

fresh

charge of

diluting

developbuilt

the

slurry

con-

automatically

any remaining

d i d not

was

typical

d e s i g n e d and

c a p r o l a c t a m was

polymerization

catalyzed

proceed

until

the

added. in

the

were

clay.

in

matrix

is

and commercialized

injection,

the

an

viscosity

small

if

percent

weight.

very or

abrasive

extrusion

c a p r o l a c t a m w e r e pumped the

injection

clay

is

mineral

much

molding.

particles

to

a product,

of

pigmented c h a i r

less

reinforced

e s p e c i a l l y impact in

a c i c u l a r shaped W o l l a s t o n i t e

stiffness

by

Wollastonite

is

molding

Calcined

properties, mineral

60

(Si02) ,

silica

injection

preferred

combination of

to

Although low

and i s

30

quartz

in

the

range of ground

be p o s t - p r o c e s s e d by

The

is

fibrous

reinforcement,

range of

excessive abrasion.

silica

greater

impact

sometimes

the

strength,

range of

particles with

a

one

consacrifice

strength.

Hundreds for

used

minerals

microns.

tributed of

Vykan.

that

obtained with very two

of

It

than

a polar

as

injection

vessel,

slurries

without

to

for

be t o l e r a t e d

and c a s t

was

is

tailored

holding

and c a l c i n e d

could not

The

6

are

and m o l t e n

were

polymer

6

After

Minerals

resin,

the

mineral

c h a r g e was

useful

obtainable

b a t c h - c a t a l y z e d , degassed and i n j e c t e d

catalyst most

stiffness

surface.

developed

Table

sufficiently

(CaSi03> and

in

initiator,

material

mineral

i m p i n g e m e n t m i x - h e a d , e q u i p m e n t was

automatically

charge

next

trademark

given

parti-

or

coupling agents

long

properties

Monsanto nylon

ment

as

by m o i s t u r e ,

mineral-reinforced the

silane

and s i l i c a t e

formulations

under

of

triethoxysilane

mineral-reinforced sold

the

use

caprolactam.

and i r r e v e r s i b l y

and r e i n f o r c e d

the

is

t

3-aminopropyl

bond between the

the

coupling agents.

nylon

mineral

severely

such as

that

permeate

adhesion

are

in

particulate

functional

silicate

since

has

presented

particulate

i n c r e a s e of

with

A polyamide such as

a polar

Company

pumpable s l u r r i e s

mineral

organic

progress

i m p a c t much l e s s

with

to

familiar.

such as molten

the

lactams

d o e s h a v e some a d v a n t a g e s .

multiaxial readily

The

Although

the

it

properties

treat

the

effective.

provide

of

commercial products

by Monsanto

polymers.

monomers

reinforced

necessary

well

the

Monsanto

initiated

of

does not

low-viscosity obtain

at

of

companies.

a r e most

reinforcement,

reduces

molding

several

authors

w o r k was

fibrous

anionic polymerization

activities the

reinforcement

reinforcement with

the

injection

by

of

this

sink-marks were

thousands method. or

other

Since

all

surface

developed which

surfaces defects

shells were

could not

compensated for

were

produced

appearance be

sur-

tolerated.

polymerization

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

load

hrs

3

psi

16-19

92-100

10

0.25

0.1-0.8

120

hrs

M-Scale

Hardness

Strain

24

12-14

0.2-018

D-785-65

D-695

Monsanto ll->45

8->45

ft-lbs

%

Monsanto 4-65

4-30

ft-lbs

psi

R-Scale

Rockwell

@ 1%

Compressive

Stress

122°F,

4000

psi,

122°F,

2000 p s i ,

under

Ball

Falling

Deformation

Dart

Falling

Impact

24

D-790 3.3-8

5

10

8-17

Modulus

Flexural

psi

D-790

3

10

9-15

5

10 18-25

Strength

Flexural

Modulus

D-638

Tensile

5-8

D-638

8-17

6.90-8.80

D-638

Procedure

ASTM

6-12

8.50-14.7

8.70^-14.8

H20

3- 7 psi

psi

-1.3%

Fail

%

3

as

Fabricated

Dry,

2- 3

10

Units

M e c h a n i c a l P r o p e r t i e s of Vykan A ( M i n e r a l -- R e i n f o r c e d N y l o n 6 )

Yield

Tensile

Fail

Elongation

Strength

Yield

Tensile

Property

Table I .

REACTION INJECTION MOLDING

142 shrinkage desks, hundred

defects.

for

The process

Castings

a variety

total was

cycle

three

to

been p u b l i s h e d ,

patents.

large

time

for

minutes.

the

of headboards,

produced for

as

individual

four the

production

terminated of

in

thirty-five

a

twelve-

pounds

were

parts.

mineral-reinforced While

technology is

of

1971.

details

of

contained in

properties

by

injection

Block

then

o b t a i n a b l e from

through

reaction

cast mineral-reinforced

R e s e a r c h was

caprolactam

Nylon

of

as

consisting

was

nylon

6

this

casting

system

a number

have

of

(10)

The range

Furniture

and luggage racks

room m o t e l .

produced

not

without

and chests

nylon

nylon

directed at

the

6 products

expanding

anionic polymerization

b l o c k copolymers and t h e i r

was

the of

fabrication

molding.

Copolymers

Chemistry Nylon

b l o c k copolymers wer

polymerization polymers.

diisocyanates groups

which

l a c t a m was the

of

(11)

basis

initiated

used for

of

initiation

prepolymers,

with polyether to

prepared from

glycols,

reaction.

areas

of

This

nylon

block copolymers are

polymeric polyols w h i c h was

the

reaction

of

contained isocyanate

caprolactam polymerization.

c a t a l y z e the

some c u r r e n t

NYRIM n y l o n mixtures

caprolacta The

Sodium

research.

from The

is

(12)

stoichiometric

and caprolactam using

described previously.

capro­

copolymer system

6 RIM

formed

end

poly

acyllactam

reactions

are

as

follows:

A)

Prepolymer

Formation Χ H0~\/0H

+ X +

1

POLYOL

I—C

I NH ( C H ) — C — 0 · ν ν / * 0 — C ( C H ) 2

5

2

POLYETHER POLYESTERAMIDE In which also of

normally functions

acts to is

the

inert

reaction,

as

so The

presence of The

copolymerization

that

multifunctional

for

the

resulting

reaction

occurs

reaction.

or

in

prepolymer

slowly

catalyst

may b e p r e p a r e d i n

solvents,

acyllactam

caprolactam polymerization,

polymeric polyol moeities.

an a l k a l i n e

prepolymer

organic

PREPOLYMER the

initiator

combine the used

by a c y l l a c t a m . in

seconds. of

prepolymer

acyllactam

ated but

the

is

See R e a c t i o n

with heat

excess

termin­ (13),

completed within

mass

c a p r o l a c t a m as

An

is

or part

in of

the

presence

the

B.

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

total

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

8.

8 L

Reaction

B.

2

5

— a

Formation.

[

0

- o-\c

POLYETHER

—0 Jb

11

c—C

->

5

PREPOLYMER

POLYAMIDE

1

NH(CH )

2

0

0

2

5

(CH ) — N H ^ C

*

—C(CH ) —NH—C—R—C-j-NF

POLYETHER POLYESTERAMIDE

2

(CH ) —U—0.

L CLJfl —R—C

Copolymer

5

C(CH ) —NH

È-—ij—C—R—C--NH

8

R

^

0

2

5

C4h N H ( C H ) ( !

CAPROLACTAM

H] Y

0 II

CATALYST

144 In

REACTION INJECTION MOLDING the

anionic

acyllactam the

polymerization

initiates

At

the

same t i m e ,

as

weak

t a m may i n s e r t The

result

is

ABA w h i c h

from

the

sented

more

equally groups

at

these

would

of

divided so

if

that

ting

structure

used

a method

in

the

block copolymer, from

the

throughout

the

of

w

the

end groups. See

active

the

M /M

the

so

the

ends

of

prepolymer

prepolymer A(BA)

nylon normal

=

n

page

selective

occurred is

only

pre-

147.

for

copolymerization ester

blocks

all

are

distribution The

chain. instead

structure

prepolymer

2/1).

d e s c r i b e d more

The

back-

that polycaprolac-

caprolactam polymerization

resulting

(i.e.,

along

sites

b l o c k copolymer or

schematic.

within

is

linkages

transfer

caprolactam available

between

weight

polymers

the

by

J.

degradation

of

the

same

curve

elucidation

fully

E.

is

and a c y l l a c t a m for

of

Kurz.

polyol

condensa-

the

alterna-

(14)

Kurz

blocks

of

b l o c k copolymer an The

molecular

bisacyllactam

weigh

determine

mer.

These parameters

final

resin

copolymer blocks

determine

product.

are

polyol

the

over

the in

The

molecular

addition

the

determined in

exercised

molecular

final

Thus,

weight

alkaline

catalyst

systems

suitable

for

the

prepared

reaction

by

NYRIM c o p o l y m e r s , catalyst

make up

the

Most

a

of

two

Grignard

such as

that

of

nylon

copolymerization

c a p r o l a c t a m magnesium with

is

caprolactam.

used—reactive

bromide, With

prepolymer

polyether

or

hydrocarbon

to

give

polyester

useful

so

caprolactam polymeriza-

and

as

of

sites

can be

copolymers.

such

types

transfer

good c o n t r o l the

nylon

percentage

reaction

the

multiple

and by

to

streams.

polyols

yield

individual

of

the block

caprolactam

in

The

in

nylon

in

or

to

final

dissolved

glycols

polymers.

is

prepoly-

polyol

are

may b e u s e d

reaction

the

the

for

reagent

These

diols

polyols

used

of

weight

very

two-package system

reactive

of

of

prepolymer

catalyst

concentrate.

resulting

and p r o p e r t i e s

The

preferred

of

amount

weight

weight

are

The

the

molecular

polymer.

both

weight

to

molecular

by p o l y o l

molecular

reactions.

and

or

points

occur

clearly

tion

tion

ester

an a l t e r n a t i n g

amount

molecular

nylon

the

initiation

acyllactam initiating

The

of

form nylon

prepolymer.

bone a c t

of

to

caprolactam polymerization

resins, ester

block copolymers.

polyols

but

may b e u s e d

these

linkages

in

will

not

in

give

polyester

act

a random copolymer

is

obtained.

block copolymers

are

determined

Other

the block co-

as

multiple

to

the

Properties The

properties

greatest which

extent

play

weight,

an

by

in

s e e n when

range

Table the

polyol

are

type

II.

polyol

of The

nylon

to

polyol

polyamide.

type,

and r e a c t a n t

Other

polyol

ratios

factors

molecular

as

well

content glycol

of

is

of

rubber

varied

phase

from

2000-molecular

with

decreased hardness, modulus

b l o c k copolymer p r o p e r t i e s

effect

changes o c c u r r i n g

are

flexural

of

as

the

conditions.

polypropylene

expected phase

role

coupler-activator

A typical

data,

ratio

important

polymerization trated

the

to

60%.

weight

increased polyether

tensile

accompanied by

0

strength,

increases

in

is

illus-

concentration

tear

tensile

For

was soft

is

these

used.

The

block

strength

and

elongation,

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

10.

recovery

and Impact

strength

is

an e f f e c t of

small

which i s amounts for

low l e v e l s

combination In better in

that

decrease

in

tensile

higher

of

as well

polyol,

and high

strength

higher

6 is

impact

end of

through

polyols

strength.

contribute

modulus,

the physical

to a

particularly property

2000 a r e r e q u i r e d ,

improvements as p o l y o l m o l e c u l a r weight Multifunctional

notch

strength.

polyols

at least

in

impact

obtained which has a

and f l e x u r a l

modulus of

Incorporation

as multiaxial

molecular weight

impact

strength.

i n a dramatic decrease

polyol a modified nylon

Molecular weights

level.

erties

Izod

o f h i g h modulus

the lower

the impact

polyol result

increased

of

balance

further

The f i v e - f o l d

reflected in

of

general,

spectrum.

strength.

accompanied by a n e i g h t e e n - f o l d i n c r e a s e i n e l o n g a t i o n —

sensitivity At

145

Nylon 6 RIM

HEDRICK ET A L .

also

is

with

increased

contribute

beyond

to better

prop-

crosslinking.

Table I I .

Effect

o f P o l y o l Content on NBC

Property Dry

as Molded

Percen 0

10

20

40

84

83

78

62

37

10,800

7,800

6,400

5 ,300

2,100

% Elongation

30

35

285

490

530

% Recovery

30

30

30

60

80

1, 3 0 0

800

410

220,000

3 1, 0 0 0

Shore

D Hardness

Tensile

Strength

PSI

Tear

60

Strength

Flexural

PLI

1,800

Modulus

PSI

390,000

Notched

280,000

Izod

Impact Ft The

Lbs./In. effects

balance

for

graphically strength ether

0.6 of

polyether

a different in

Figure

content

is

This

impact

Izod

occurs

linear

in

ether,

the impact rate

14% a n d h i g h e r impact

N.B.

strength/stiffness

are

illustrated

and Izod

polyether

N.B.

impact

content.

modulus e x h i b i t s

u p t o 30% p o l y e t h e r .

range.

But in

starting

This

copolymers as well

A t t h e same also

occurring at a

modulus.

Thus,

a much b e t t e r

phenomenon o c c u r s

as other

poly-

a t a b o u t 14% p o l y -

impact

flexural

copolymers have

and s t i f f n e s s .

As

an expected

The i n c r e a s e i s

an increase i n

the decrease

polyether,the

strength

of

increases.

c u r v e shows

nylon block

modulus

flexural

linearly

strength

than

copolymer

Flexural

the low polyether

much h i g h e r of

4.

increased,

time,

5.7

content on the impact polyether

a r e shown a s a f u n c t i o n

decrease.

polyol

1.6

at

balance

with

other

rubber-reinforced

resins.

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

146

REACTION INJECTION MOLDING

Structure While

and Morphology

the polyether

and g r e a t e r continue in

rubber

tensile

to provide

high

phase r e s u l t s

elongation,

crystallinity

polymer melting

points

scanning calorimeter

linear

block

(polyether) in

a n d a t 45 t o 5 0 ° C

temperatures

216°C

(nylon The

are

6 T ) m

function

of

content

copolymers is

0 to

deflection

in

a t -60 to

These

transitions

polyether

on

-70°C occur

content.

Melt-

copolymer to

torsion

similar

to,

pendulum d a t a

o f NBCs

ranging

representing

in

polyether

9 a n d 18%

but not identical

(14)

(G*) as a polyether

with nylon

6,

the dashe

at -60°C,

th changes i n

the nylon

t

region

g

a t 45

to

are not apparent. F r o m t h e same d a t a ,

function

of

temperature

ether

were

nylon

t g a r e more

from

deleted for

37 t o

while which

This

tends

amount

Another ether,

clarity.

clearly

due to n y l o n

In

Figure

is

is

content

regions

becomes

by the nylon

region

which

tration,

nylon

becomes

phase.

elastic

give

for

increased

to

In In

stiffen

of

temperature

to

the

the range

decrease transition.

in

the

polyether the nylon

the polyether

copoly-

0 t o 20% p o l y -

the mid-range of

phase with

to

more

crystallinity

and also rise

and a t higher

the dispersed

acting as crosslinks

is

poly-

p e a k s become more p r o n o u n c e d , these

content.

the continuous

as a

9 a n d 56%

the changes i n morphology o c c u r r i n g

changes i n polyether

nylon

plotted for

6 the damping peaks

As p o l y e t h e r

6 in

amorphous m a t e r i a l

(G") i s

The curves

to broaden the t r a n s i t i o n of

a r e b e c o m i n g more

Heat

6.

shown.

polymers lites

modulus

Figure

may b e e x p l a i n e d i n p a r t

reason

mer w i t h

the loss in

66%, t h e - 6 0 ° C p o l y e t h e r

the change

diffuse. the

resulting

pendulum s t u d i e s

complex modulus

a series

The c u r v e s

much more p r o n o u n c e d w h i l e 50°C

phase

to heat s a g .

65% p o l y e t h e r

from

5 a n d show for

66%.

are quite

shown

curves

Figure

temperature

from

block

strength

blocks

20% p o l y e t h e r .

dynamic modulus

reproduced i n

which

for

6).

range of

from 1 9 5 ° f o r

impact

nylon

resistance

transitions

(nylon

the entire

range

the hard

and t o r s i o n

c o p o l y m e r s show

a l l copolymers f o r

ing

for

and high

Differential nylon

in higher

the high melting

37%, t h e concencrystal-

rubber

phase.

Resistance

Table

III

shows

copolymers modulus range polyol

with

ratio

the effect polyol

at

even though is

contents

- 2 9 ° / 7 0 ° C shows t h e modulus

i n c r e a s e d from

in

on f l e x u r a l

the mid-range

only

slight

modulus

20-40%.

change

shows a n e i g h t e e n - f o l d

over

for

The l o w the p o l y o l

decrease

20-40%.

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

as

HEDRICK ET AL.

Nylon 6 RIM

Λ Τ

POLYETHER

^χ_χ_χ_χ_χ_χ_0-0-0-0-Χ-Χ-Χ-Χ-Χ-Χ-0-0-0-0-0-Χ-Χ-Χ-Χ-Χ-Χ-0-0-0-0-Χ-Χ-Χ-Χ-Χ-Χ'^ NYLON BLOCK COPOLYMER SEGMENT

400 ^/^IZOD 300 i-12 Δ

g

200

V \

FLEXURAL MODULUS

as g

w 100

L

4

1-2 10

20

30

50

40

COPOLYMER % POLYOL

F i g u r e 4 . Modulus-impact balance f o r n y l o n b l o c k (dry-as-molded).

copolymer

9.0

8.0

-100

-50

0

50

100

150

200

Temp. (°C)

Figure 5 .

Dynamic modulus curves f o r n y l o n b l o c k

(complex modulus

^^^ CfliàfCll Society Library 1155 1«h 8t N. w. W a shington. 0. C 20036 In Reaction Injection Molding; Kresta, J.; v e r

copolymer

a

ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

REACTION INJECTION MOLDING

Figure

6.

Loss

modulus

versus

temperature

for

nylon

block

copolymer.

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

10.

Nylon 6 RIM

HEDRICK ET AL.

Table

III.

149

NBC T e m p e r a t u r e - M o d u l u s Polyol

20 Flexural

Content

35

30

40~

Modulus

@ -20°C

296,000

80,000

54,000

28,000

23°C

197,000

42,000

22,000

11,000

70°C

71,000

21,000

17,000

9,000

Modulus

Ratio

-29 /70°C

4 2

Q

The and

contribution

soft-block to

C as

Even

163

at

quite

to

crystalline

high melting

low

low

heat

values end of

are the

sag values

which

automotive

could

related modulus

relate

to

assembly

eliminate

the

o p e r a t i o n and permit

IV.

Flexural PSI

to

the

.125" Moisture

blocks

modulus.

sag values

were

the

ability

line

paint

requirement

use

of

the

of

fabricated

bake-oven for

cycles—

a separate

same p a i n t s

used

off­ for

NBC H e a t

Sag/Flexural

Modulus

Modulus

Heat

Sag

163°C

@ 230C

-

0.1

115,000

.06

60,100

0.15

33,500

0.15

24,700

0.2

11,000

0.34

thick

in.

specimen 4"

overhang

-

60

minutes

Effect

effect

of

documented.

moisture (15)

copolymers to

requirements

applications nylon

flexural

spectrum,

169,000

block

6

components. Table

The

nylon

sag e x h i b i t e

these

very

painting

steel

heat

withstand

an a b i l i t y line

the

3Λ

low. The

parts

the

of

3^2

hard-phas

sag

at

3^8

1

resistance

of

Response

block

for

on n y l o n

Because of

6 resins

this,

the

is

well-known

susceptibility

moisture

absorption

was

exterior

automotive

body p a n e l s and

requiring

dimensional

copolymer formulations

expected.

and of

wellnylon

Evaluation other

stability

indicated that

would not

meet

early

specifications

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

150

REACTION INJECTION M O L D I N G

with in

regard

to

not

sufficient The

in

use

moisture

tion not

of

creased fiber

moisture

rate give

in

absorption but

of

Polyol of

effect

of

relativ

Figure

8.

Under

the over

60%

of

end-use, the

Figure

9.

of

The

glass

by r e i n f o r c e m e n t appear

applications Molding

parts

our in

resin

purposes,

which

they

two

to

large ment part, ments

can be

resin

fully

glass as to

as

for is

to

of the

C gave

milled

glass

for

resin

exterior

fiber

growth reflects

a maximum

fiber.

dimensional

for

in

Polyol

to

glass

The

humidity

reinforced

parameters

6.

be s u f f i c i e n t

immersion

reduced

milled

The

nylon

improvement

while in

decreased

well.

relative 30%

significant

only

of

These automotive

stability.

more

to

transfer

the

as

impregnate to

required

static

set

up

to

low-

d e f i n e d as

are

or

carried

molding,

molding

streams

parts

produce

casting.

are

and i n j e c t e d

RIM

to

can be

rotational is

a

combined and mixed

into

form a p l a s t i c

mold with

molding,

mold and the

impart

much h i g h e r

injection

device

are

injection

molding,

reactive

systems

prepolymers

reaction

rapidly

the

or

a c l o s e d mold

part.

To

foamed to

compensate

some

dynamic mixers

compensate for

degree.

a r e employed

polymerization

additional material.

Thus,

a

produced.

percentages of

In

1/16"

e.g.,

casting,

by p a c k i n g

into

so

of

Improvement

values

reaction

pumping systems

part In

with

Β

in­

insufficient

identical

almost

requiring

shrinkage,

low-pressure

shrinkage

placed

is

C not

absorption

illustrated

transfer

or

polymerize

polymerization

solid

of

A and

stability,

gave a f u r t h e r

nylon-based polymer

an impingement mixing

the

absorp­

greatly

Polyol

f r o m monomers

processes;

casting,

For

In

of

added

within

of

directly

several

pressure

where

but

C)

Expansion

areas

polymerization

finished

process

be w e l l other

of

types

Polyols

of

C gave

25%

was

Processes

Anionic by

to or

improvement

Use

range of with

three

Reinforcement

conditions

C is

fiber.

effect

for

dimensional

NBC f o r m u l a t i o n

The

with Polyol

The

copolymer appears to

the

original

7

absorption,

in

decrease

stability.

copolymer.

well.

rate

Polyol

improvement.

of

(Curve

this

in

of

6.

C c o p o l y m e r was

The

values

and

the

The

reinforcement

applications.

expansion.

stability

orientation

with

critical

a b s o r b e d , but rate

20%

as

fiber

NBC g a v e u n e x p e c t e d i n c r e a s e

Figure

degree of

polyol variation

reinforcement

0.3%

the

for

moisture

in

improvement

when

expansion

a

of

further

below,

third

nearly

in

nylon

total

the

typical

of

i n c r e a s e d the

applications,

shown

blocks

that was

dimensional

data

over

absorption.

glass

dimensional

level

absorption most

required

rubber

expansion

of

Polyol

amount

for

polyol

specifications A

the

use

shown

will

decrease

out

give

moisture

the

is

illustrated meet

from

absorption

blocks.

only

the

to

on l i n e a r

polyol

as

e x p a n s i o n due to

expansion r e s u l t i n g

for

c l o s e d mold which

the

possible

RIM

casting, rotates

or

the

long

short

mat the

fiber to

fiber

is

injected use

so of

reinforce­

the

molded

reinforce­

processes.

reactant

around

or

is

permits

and toughness

with

casting

the

stream

This

fiber

maximum s t i f f n e s s is

reinforcing

liquid

reinforcement.

heavy continuous

than

rotational

the

a preformed

reacting

one o r

mixture

is

more axes

introduced so

as

to

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

into

produce

HEDRICK ET A L .

Nylon 6 RIM

3.0

5

10

15

20

25

36

Days Water Immersion 72 F F i g u r e 7. copolymer.

Effect

of water immersion on e x p a n s i o n

of n y l o n

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

REACTION INJECTION MOLDING

3.0L

% Relative Figure 8. Effect b l o c k copolymer.

Humidity

of r e l a t i v e h u m i d i t y on e x p a n s i o n of n y l o n

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

HEDRICK ET AL.

Nylon 6 RIM

2.0l

S

10

Days

IS

20

23

Immersion

F i g u r e 9 . E f f e c t of water immersion on r e i n f o r c e d f o r c e d n y l o n b l o c k copolymer ( P o l y o l C ) .

and

unrein-

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

154

REACTION INJECTION M O L D I N G

a uniform l a y e r of polymer on the hollow part is produced. The

last

Reaction

important

First,

processes are not

Injection

Nylon-based molding

two

RIM

from urethane

RIM

systems

the

RIM

equipment and

found most

points

at

heated

tanks,

pumps,

accomplished

or

water

by

their

two

not,

streams.

chemically

are

typically lines

Third, those

of

versus for

5

to

very are

30

gel

temperatures

for

stability.

At the

of from

Thus,

of

30

part longer

of

the

the

are and

these

materials

making

them

equipment must

have

commercial

practice,

circulating

time

times

of

this

hot

oil

they

from Union

Thus,

the

psig

is

are

of

This

allows

is

of

45

to

the

the

lower

order part

of

rate

5-10

surface

are normally

these

temperatures,

seconds for

also 3-4

than

reasons until

reactants the

mold

parts

difference

mold

of

about

is

the

temperature

a result

of

the

low

at

gel

and For

and tempera­

times

are

thickness.

reauired

for

by c o n d u c t i v e h e a t i n g . very

Kcai/mole versus exotherm

run

1/8-inch time

is

minutes.

quality

molds

is

low-

seconds,

than

At

only

of

systems.

several

Second, 90°F

120

RIM

to

one-tenth use

monomer

polymerization

on the

generation,

time

is

hydraulic

nylon

gel

pressures

energy c o n s e r v a t i o n and product

temperatures,

rise

energy

for

and 3 2 5 ° F .

60

streams

a r e much l o n g e r

in

to

normal

since both

There are

30

and

their

required

horsepower

attained.

viscosities

they

This

soluble

the

l a c t a m monomer,

range.

systems

rubber

typical

Carbide,

mixxng n e a d

i.iie o r d e r

temperatures or

in

xmpingemenL

urethanes.

polymer

contain

over

be­

spots.

compared w i t h

a comparison of

solutions

on

preferred

hot

Additionally,

nylon

A typical reaction

NYRIM 2000 n y l o n

are

of

whether

systems.

typically

tool,

methods

and l a c k

2700

and lower

mixed stream

the to

caprolactam,

urethanes.

In

two

for

150-300

these

to

reactants

This

are

urethane

reasons

the

10 RIM

in

the

b e t w e e n 250

typically

RIM

viscosity

low

optimum p h y s i c a l p r o p e r t y tures

in

comparable.

held at

pot

release

systems polyol

RIM,

copolymer from Monsanto,

high molecular weights

life

urethane

streams,

low

seconds for

First,

typically

the

first control

system,

and v a l v e s

rhe

Thf

and so

for

urethanes,

this.

RIM

liquid

equipment w i t h

of

systems

low

required

pressure

nylon the

nylon

temperatures.

quite

quite

used, that

the

reactive

block

operating

is

Thus,

See F i g u r e

n y l o n - b a s e d RIM

are

in

and molds.

are very

a t y p i c a l urethane

mixing of

lines

uniformity

NYFTM 2 0 0 0 n y l o n in

several

by e n c l o s i n

the

or

of

in

electricall

Second,

ranges

common u s e

hands and t a p e s .

urethane

for

Unlike

1 5 8 ° F and 3 2 0 ° F r e s p e c t i v e l y ,

by j a c k e t i n g

systems,

modifiers of

in of

useful

lactam.

room t e m p e r a t u r e .

is

design of

conditions.

monomers

solids

A

urethanes.

Impact

isocyanate materials

of

with

cavity,

differ

have m e l t i n g

cause

the

systems

the

or

practiced

of

Molding

ε-caprolactam and l a u r y l

ovens

surface

aspects which

process

heating

inner

is

low

18-20 shown

heat

of

kcal/mole in

Figure

reaction for 11

block copolymer.

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

for

H E D R I C K ET A L .

Nylon 6 RIM

ιο,οοα

Figure

10.

Viscosity

of

urethane

a n d NYRIM

raw m a t e r i a l

streams

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

REACTION INJECTION M O L D I N G

Figure 1 1 . In-mold reactant made from NYRIM 2 0 0 0 .

temperature d u r i n g c u r e of a p a r t

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

10.

The in

net

nylon

less

effect

RIM.

part

jection although

is

This as

rates

method of

as

high

foaming.

as

In

tion

systems.

density the also

of

optimum

Blowing

frequently

1.0-1.4

added

to

systems

the

and urethane reactant

in

external

used. lb

In-

parts,

the

systems

streams

tanks

density

the

in

the

typically

b y means o f

microcellular

Freon

is

are

p i p e l i n e mixers

of

such as

control

are

be used and produces

common o n 3 - 4

measure and c o n t r o l

agents,

to

l b s / s e c o n d can be u s e d .

control

to

rates

pumping u n i t s

lb/second are

by f r o t h i n g

gauges are used

tanks.

injection

smaller

between n y l o n

by use

For

lower of

urethanes,

nucleated with nitrogen or

use

0.1

difference

speed a g i t a t o r s

permit

when f i b e r - r e i n f o r c e d

low

as

A fourth

to

permits

anisotropy

rates

157

Nylon 6 RIM

H E D R I C K ET AL.

high-

recircula-

foams, froth

nuclear

density

in

chloro-fluorocarbons, and shrinkage

values

are

of

urethanes. Nylon

RIM

gen content blanket

used

soluble

in

The

nylon

upon

systems

is to

the

inert

foam i s

throttling

the

and

material

but

pressure

hold

control

of

tanks.

the

of

nitro-

nitrogen

Nitrogen

is

quite

and

during

produce

as

the

impingement mixer

nitrogen

The

fact

is

orifices

much l e s s

soluble

the

RIM

that

nucleating agents

Accurate target ties,

in

nylon

simpler.

have a l s o

only

to

blend of

achieve

in

been

the

streams

Chemical

polymer

are

than

liquids,

blowing

successfully

rate,

not

that

ratio

either

kinetics

Internal

not

agents

used

in

nylon

require

a p p l i c a t i o n of

urethane

the

urethane

build-up tating

in use

every

reactant

head.

mold,

urethane release internal

third

Newer shots

spray

to to

high

as

The

All

Nylon

affect

show

the

determined the

stream

systems

proper-

of

contains

will

well.

of

physical

second

5% d o n o t

for

a mold r e l e a s e streams

or

These

agent,

to

the

tanks

reactions

even with

internal

well

contains

only

can be

formu-

any e f f e c t

developed

urethanes.

on

the

because

mold r e l e a s e

quality

tool. that smooth

Monsanto's is

RIM

a

react

to

with

problems

of

necessiSome

newer

introduce mold r e l e a s e at systems nylon

paintable.

show

they

have caused

permit

b e made b e t w e e n a p p l i c a t i o n s o f the

a soap or

mold s u r f a c e s .

to

nylon

urethanes

cannot be added

spray-on mold r e l e a s e s ,

scrub

for

Most

a wax,

Many m o l d r e l e a s e s

component stream

mold r e l e a s e

a high

stream which

technology is

shot.

chemicals.

a

the

being developed

p e r i o d i c shutdowns

systems

where

is

the

part

as

0.5%

essentially

being o f f - r a t i o

as

systems

within

properties.

mold r e l e a s e

after

in

are

components.

Thus,

changes

while

the

materials

made

to

finished

nylon

RIM

nylon

isocyanate ratio.

physical properties.

or

it

desired

modifier

systems

silicone,

the

with

be h e l d

to

solution.

lated

important

typically

sensitive

materials

reaction so

of

and rubber

catalyst

less

must

being very

properties

initiator

is

ratios

order

these

the

metering

stream

physical

mix

the

systems.

Urethane

by

nitrogen-blown

makes a c c u r a t e m e t e r i n g

solid

RIM

the

through

monomer.

froths,

also

caprolacta

polymerization, in

are

p r o v i d e d by s e t t i n g

surface

In is

RIM

from

external system

certain required

0

to

the

50

mold

contains

an

applications on a p a r t ,

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

a

158

REACTION INJECTION M O L D I N G

thermosetting the

reverse

tial

release

part

to

face

quality

result

systems

from

the

in

lies

of

the

surface,

adhere to of

the

then

tool.

tool

in

the

extent

of

green-strength

reacts

parts

are

The

state

with

fully of

the

removed

from

tougher

and t y p i c a l l y

difference

the

in

tool

the

surface

enough i n

A

similar surface

may a l s o

the

be u s e d . RIM

mold.

Many

mold to

generate

the

part.

reaction before

isocyanate in

the

sur-

reverse

and n y l o n

the

of

the

Parts

atmospheric

part.

Nylon

mold.

the

urethane

which

breaks

each

results off

shot.

in

flash

and must

Nylon

RIM

which

is

be manually flash

is

much

come

operation

between urethane are

lower

mold r e l e a s e s

produces differen-

maximizing

replication.

a 5°F

complete the

after

show

demolding and h a n d l i n g

residual

cure of

the

between urethane far

that

provides

surface,

cure obtained in

for

cured in

weak a n d b r i t t l e ,

surface

This

allowing

surface

Silicone

difference

oven post-cured to

moisture

fairly

the major

tool

part.

the

tool

are polymerized just

sufficient

time

tool

and f i d e l i t y

last

urethanes

parts

u s e d on

can be o b t a i n e d by m a i n t a i n i n g

The

RIM

is

unseen surface

preferentially

temperature

are

mold r e l e a s e

or

quite

used for

shots,

means t h a t

comparable,

urethane

in

RIM.

cycle

spite

of

times the

Commercial

for

nylon

and

urethane

shorter closed-mold

cycles

of

2.5

minutes

are

common. Equipment As

Requirements

a result

machines

of

the

system

can be simpler

The

nylon machines, of

insulated,

but

tion

and have l e s s

rates The

tionally, lids

they

tanks

anchor-type valve

differences

and lower

for

the

need

if

should

any

should

be h e a t e d to

which might

plug

pressure and l i d

ethylene-propylene should

be both

The This

avoids

should

clean

out.

to

and

and l i n e s of

where

flexible

are

jacketed,

it

preferred

side

Should

streams, the

oil

nylon

then than

RIM

ers

of

RIM

for

nylon

of

the

it

is

visa

reaction

be set

occur more

versa. speed

of

of

to

avoid

occur.

Tank

l a c t a m monomer

Teflon the

resin

or

monomer.

to

allow

material when

Tanks

that

the

jackets

oil

pumps

that

to

jacket

the

stainless

Where

these

the

to

oil

will

lines the pressures

leak

into

affect

Many m a n u f a c t u r -

valves

steel.

Teflon

reactant

adversely

and p h y s i c a l p r o p e r t i e s .

m a c h i n e s b e made o f

with

keep

and All

machine

lined

and the

reactants

tanks,

lines

be coupled

contamination w i l l all

the

are used.

simplify

required.

likely Oil

to

hoses

are

between the

recirculation. in

they

lines

equipment recommend t h a t RIM

up

the

materials

recirculating

leakage

type

speed

Addi-

pressurization/degassing

be s e l f - d r a i n i n g

preferred

low.

slow

be u s e d .

flush

be of

surfaced flexible

are

suction

or

injec-

vacuum-capable.

be d e s i g n e d to

is

valves

control

inside

to

reinforcement

a v o i d a t t a c k by

reinforcing

Smooth

are

the

RIM

control.

be a g i t a t e d w i t h

be of

should

should

temperature

settling

lines

rubber

pressure

tanks

improves

relief

have lower

ratio

avoid sublimation

seals

nylon

heated and

units,

systems of

outlined,

urethane machines.

be w e l l

accurate

settling

also

Agitator

for

reinforced

bottom v a l v e s

than

pressure

nylon machines should

should

ports.

previously cost

c o u r s e , must

can be lower

agitators

plugging

in

and

Mild

fittings steel

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

and

10.

HEDRICK ET AL.

galvanized

Nylon 6 RIM

159

steel

tanks

have been

copper

and brass

lines

and f i t t i n g s

of

the

material

mately

painted.

was

Both rotary for

nylon

forced

not

b e made

Nitrogen

suitable.

Tank

with

foam d e n s i t y

reinforcement volumes

of

nitrogen

to

is

gas

be

into

however,

parts

metering

were

units

units

have

color

be

u l t i -

to

are

are

as

the

suitable

best

for

rein-

the

tank

for

nylon

plating

resistance

of

epoxy

a few

is

to

30

psig

of

of

all

less

storage

than

are used,

and

5 ppm

is

depending upon

mix

incorporation

tanks

is

Following

adjusted

tends

when

to

of

the

large

dissolved

nitrogen

c a n b e made

aluminum,

fiberglass

carry

degassing,

by c o n t r o l

systems

steel,

required

pressure.

from a wide

kirksite

variety

and n i c k e l .

Chrome

als

mad

system

parts

0

inerting

content

the

RIM

has

molds

tooling

gas

its mix.

including

and n i c k e l

dry

produced.

the

in

for

from

used as

Molds materials

than

the

piston

a moisture

pressures

Vacuum d e g a s s i n g o f

of

because

Displacement lance

used,

a p p l i c a t i o n s where

systems.

tanks.

the

an i s s u e

in

pump a n d p i s t o n - t y p e

RIM.

P r o v i s i o n must hold

successfully

has

been

before

demonstrated

failing.

that

will

Development work

produce

more

continues

in

this

area. In used

most

for

lines

should

done a t means or

respects,

urethanes. be
, 1

[A] / [I] (mol/100 mol CL) 0.6/0.1 0.6/0.15 0.6/0.2 0.6/0.3 0.6/0.4 0.6/0.6 0.7/0.4 0.7/0.6 0.7/0.7 0.8/0.4 0.8/0.6 0.8/0.7 0.9/0.6 0.9/0.7 0.9/0.9 1.0/0.6 1 .0/0.7 1 .2/0.6 1.2/0.9 1.2/1.2 3.0/0.6

Monomer Conversion (λ) %

High Polymer Y i e l d

-

76.3 85.6 93.7 96.2 95.3 95.6 94.1 96.1 95.6 93.5 96.1 96.1 97.3 95.2 95.6 96.2 95.6 96.0 95.7 95.5 88.3

98.2 98.2 96.7 98.4 98.2 96.6 98.4 98.8 97.8 98.5 98.2 98.5 98.1

-

98.7 98.3

-

%

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

REACTION INJECTION MOLDING

168

recently have been s a t i s f a c t o r i l y s o l v e d ( 2 2 - 2 5 ) . The aforementioned N-trif1uoroacety1ation r e a c t i o n runs as f o l 1ows:

(1) Complete s u b s t i t u t i o n of the nitrogen-bonded hydrogen and easy r e p r o d u c i b i l i t y are the most r e l e v a n t aspects of the above r e a c t i o n . The N-trif1uoroacetylated d e r i v a t i v e of PCL i s q u i c k l y s o l u b l e in many solvents (such as acetone, THF, dioxane, chlorinated hydrocarbons, etc.) and can e a s i l y be analyzed by conventional GPC apparatus. P r e l i m i n a r y data on IV. It i s evident that equimolar concentrations of activator and initiator produce PCL polymers c h a r a c t e r i z e d by a r e g u l a r l y decreasing p o l y m o l e c u l a r i t y index Q, from c a . 2.6 to 2.0. In Figure 1 the number of polymer molecules formed per acyllactam molecule i s p l o t t e d as a f u n c t i o n of i n i t i a t o r concentration . The actual values should be compared to the ' t h e o r e t i c a l ' value of 1, which corresponds to the assumption that the number of macromolecules would be equal to the number of a c y l l a c t a m molecules (26J, as in the i d e a l case of a s t e p - a d d i t i o n of lactam anions to a constant number of growth c e n t e r s . It i s evident t h a t , by i n c r e a s i n g [I] at equimolar concentrations of a c t i v e s p e c i e s , there i s a r e g u l a r decrease in the number of polymer molecules Ν per a c t i v a t o r molecule. Moreover, a l l experimental values of [N] / [A] are lower than 1, i n the [I] range from 0.5 to 1.5 mole %. E x t r a p o l a t i o n to i n f i n i t e d i l u t i o n of caprolactam anions shows a c o n s i s t e n t cohincidence with the c a l c u l a t e d value of 1, in f u l l agreement with theory. From the above data i t i s evidenced t h a t , i n the experimental range of i n i t i a t o r concentrations we used, polymer molecular masses are higher than expected. Indeed, a d d i t i o n a l growth c e n t e r s , i.e. new polymer c h a i n s , can be produced by d i s p r o p o r t i o n a t i o n r e a c t i o n s such as the f o l l o w i n g one, induced by strong bases: •CO-N—CO

+

Θ

ΝΗ

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

(2)

11. ALFONSO ET AL.

Table I I I .

[A] /

169

Activated Anionic Polymerization of e-Caprolactam

Monomer Conversion and High Polymer Y i e l d i n Polymerization" Runs where [A]/[I]*1 Monomer Conversion High Polymer Y i e l d (λ)

[I]

(mol/100 mol CL) 0.6/0.6 0.6/0.9 0.6/1 .2 0.6/1 .8 0.7/0.7 0.7/0.9

Table [A] / [I] (mol/100 mol CL) 0.5/0.5 0.7/0.7 π η/π π 0.9/0.9 1.2/1 .2 1.5/1.5

%

%

94.9 94.9 93.6 95.6 95.2

-

98.2 98.2

IV.

GPC Data on PCL Samples — -3 Mn-10

27.04 19.74 /16.77 \l7.42 14.40 14.34

3 — Mw-10

70.63 46.09 Γ39.32 \38.37 32.42 29.25

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

Q

2.61 2.33 Î2.34 \2.20 2.25 2.04

REACTION INJECTION MOLDING

_J

0.2

I

I

I

I

0.6

1.0

I

1

L

U

[l] [mol /o] ;

e

Figure 1. Number of polymer molecules formed per acyllactam molecule, as a function of initiator concentration in the case [I] = [A].

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

11. ALFONSO ET AL.

Activated Anionic Polymerization of crCaprolactam

whereas C l a i s e n - t y p e condensation r e a c t i o n s , such those involving the following speci es ( 1_6 ), r e s p o n s i b l e f o r an increase of molecular masses:

171

as are

•CH-CO-N—CO or

Actual balance between the two opposite e f f e c t s determine the average value of polymer molecular mass and i t s distribution. From our data i t seems that the p r e v a i l i n g e f f e c t i s caused by type (3) r e a c t i o n s , which are more and more r e l e v a n t as b a s i c i t y of the medium i s i n c r e a s e d . Side Reactions and S t r u c t u r a As already mentioned, the a c t i v e species (imide groups and lactam anions) undergo a s e r i e s of side r e a c t i o n s , which induce the formation of i r r e g u l a r u n i t s along the chains. Not only the r e g u l a r i t y of the chains i s affected, but also the whole p o l y m e r i z a t i o n process as well as the polymer end p r o p e r t i e s are markedly modified (Jj5) . The s t r u c t u r e s , a r i s i n g from the aforementioned C l a i s e n - t y p e condensation r e a c t i o n s , are very r e a c t i v e : on one hand, they r e - c r e a t e growth centers and, on the other, they are r e s p o n s i b l e f o r the formation of heterogeneous groups, such as d e r i v a t i v e s of i s o c y a n a t e s , u r a c i l , malonamide, e t c . , which act as c o l o r centers and i n v e r s i o n points of chain r e g u l a r i t y . As a consequence, together with l i n e a r c h a i n s , branched and c r o s s l i n k e d s t r u c t u r e s are also formed. They s t r o n g l y a f f e c t molecular masses, MMD, and s o l u t i o n p r o p e r t i e s . Moreover, these n o n - c r y s t a l l i z a b l e u n i t s cause a decrease of both the polymer melting temperature and the crystallization rate, as well as a poorer thermo-oxidative s t a b i l i t y (16). In order to minimize these e f f e c t s , which may be r e l e v a n t a l s o to RIM technology, we have studied the r o l e of a c t i v e species concentration on the UV absorption spectra of the r e s u l t a n t polymer. The data are given i n Figures 2 and 3, where the e f f e c t s of equimolar and non-equimolar concentrations of a c t i v e s p e c i e s , r e s p e c t i v e l y , are shown. In Figure 2 the UV absorption c o e f f i c i e n t of PCL samples appears to be a l i n e a r f u n c t i o n of each a c t i v e species

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

172

REACTION INJECTION M O L D I N G

0.2

0.6

1.0

U

[l].[mol%]

Figure 2. Optical density of PCL samples at λ= 276 nm as a function of initiator concentration, in the case [I] = [A].

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

ALFONSO ET AL.

Activated Anionic Polymerization of e-Caprolactam

[A] mol /. e

U

I

0.2

I

I

I

I

0.6

1.0

ι

ι 1.4

ι

I

[l].[mol /o] e

Figure 3. Effect of activator concentration, as constant [ I ] , on polymer optical density at λ= 276 nm. a) [I] = 0.4; b) [I] = 0.6; c) [I] = 0.7; d) [I] = 0.9.

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

174

REACTION INJECTION MOLDING

c o n c e n t r a t i o n in the range between 0.3 and 1.5 mole %. It i s reasonable to assume that the UV absorption i s directly proportional to the t o t a l amount of side products a r i s i n g from the C l a i s e n - t y p e condensation r e a c t i o n s , which are c a t a l y z e d by strong bases. Thus, the a b s c i s s a i s f o r m a l l y expressed i n terms of i n i t i a t o r c o n c e n t r â t i ons. In Figure 3 the e f f e c t of a c t i v a t o r c o n c e n t r a t i o n on the UV absorption c o e f f i c i e n t of our polymer samples, at constant [I] , i s g i v e n . Almost p a r a l l e l l i n e s , well joined to the i n t e r p o l a t e d values on the equimolar c o n c e n t r a t i o n l i n e , have been found. From the whole set of above data i t can be i n f e r r e d t h a t , by s u i t a b l y p l a y i n g with appropriate c o n c e n t r a t i o n s of the a c t i v e s p e c i e s , i t i s p o s s i b l e to reduce the amount of s t r u c t u r a l i r r e g u l a r i t i e Polymeri ζ ation K i n e t i c s The whole p o l y m e r i z a t i o n k i n e t i c s has been followed by means of the a d i a b a t i c r e a c t o r method ( 3 , 6 ) , which allows to simultaneously determine p o l y m e r i z a t i o n times and rates. In Table V d a t a , r e l a t e d to the overall p o l y m e r i z a t i o n time, tp , as well as to the i n i t i a l and maximum rates of p o l y m e r i z a t i o n , are g i v e n . A l l these parameters are, of course, very r e l e v a n t to RIM technology. In Figure 4 the o v e r a l l p o l y m e r i z a t i o n time i s p l o t t e d as a function of one or the other a c t i v e species c o n c e n t r a t i o n . A h y p e r b o l i c type dependence of t on [active species] i s e v i d e n t , with a very sharp decrease of tp i n the c o n c e n t r a t i o n range between 0.3 and 0.7 mole %, and a much slower decrease at higher c o n c e n t r a t i o n s . At the highest l e v e l s of a c t i v e species c o n c e n t r a t i o n s , t p is very low ( c a . 3 min) and t h i s value compares r a t h e r well with the usual r e a c t i o n times f o r the RIM technology. Non-equimolar concentration conditions roughly f o l l o w the same p a t t e r n , as evidenced from the data quoted i n Table V, and allow to underline the prominent r o l e of [I] on t , whereas [A] has a much lower relevance on i t . The i n i t i a l p o l y m e r i z a t i o n rates show a dependence on the first power of [A] and 0.9 power of [I] , as evidenced i n Figure 5. With only a few exceptions almost a l l the experimemtal points are well a l i g n e d on the s t r a i g h t line, passing through the o r i g i n . The 0.9 exponent indicates an almost complete d i s s o c i a t i o n of the p

p

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

11. ALFONSO ET AL.

Activated Anionic Polymerization of trCaprolactam

175

Table V. Overall P o l y m e r i z a t i o n Time, I n i t i a l and Maximum P o l y m e r i z a t i o n Rates i n Runs with D i f f e r e n t Amounts of A c t i v a t o r and I n i t i a t o r [A] / [I]

Overall Polym. I n i t i a l Rate Maximum Rate Time, t (dx/dt) -10 ( dx/dt ^ 1 0 (mol/100 mol CL) (min) (min" ) (min" ) 2

o

p

0.3/0.3 0.3/0.3 0.5/0.5 0.7/0.7 0.7/0.7 0.9/0.9 1.2/1 .2 1.5/1 .5 0.6/0.4 0.7/0.4 0.8/0.4 0.7/0.6 0.8/0.6 0.9/0.6 1.0/0.6 0.8/0.7 0.9/0.7 1.0/0.7 0.7/0.9 1.2/0.9

12 .05 11 .05 8 .10 4 .90 5 .40 3 .80 3 .70 3 .15 6 .50 9 .30 7 .85 6 .05 5 .60 5 .40 3 .95 5 .15 5 .70 4 .70 5 .15 5 .40

1

1

1 .95 1 .41 3.39 6.98 7.40 9.41 19.28 23.63 3.69 3.37 4.54 5.61 7.10 4.78 8.64 7.49 6.11 11.12 8.57 9.77

1

3.38 3.74 5.17 8.01 8.28 10.04 13.64 15.82 5.69 4.30 5.06 6.77 7.90 8.21 9.43 9.90 7.77 10.96 8.48 7.96

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

176

REACTION INJECTION MOLDING

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

ALFONSO ET AL.

Activated Anionic Polymerization of e-Caprolactam

Figure 5. Initial polymerization rate as a function of acti species concentration.

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

REACTION INJECTION M O L D I N G

178

caprolactamate ' a l t i n our experimental c o n d i t i o n s , at variance with previous f i n d i n g s ( 1 6 ) . From the data of Table V i t i s also evident that the maximum polymerization rates in quasi-adiabatic conditions are 10-20 times higher than the i n i t i a l r e a c t i o n s r a t e s . At i n c r e a s i n g concentrations of the a c t i v e s p e c i e s , the r a t i o between the two rates r e g u l a r l y decreases. Cone!usions The RIM process f o r m a t e r i a l s based on PCL r e q u i r e s a stringent control of the many r e a c t i o n parameters which strongly a f f e c t the whole pattern of the a c t i v a t e d a n i o n i c polymeri z a t i on. Among these parameters c o n c e n t r a t i o n s play a very r e l e v a n t r o l e . The present study underlines t h e i r i n f l u e n c e on the p o l y m e r i z a t i o n k i n e t i c s and polymer p r o p e r t i e s . 'Optimum' c o n d i t i o n s f o r each of the f o l l o w i n g aspects have been found: high polymer y i e l d , maximum monomer conversion, initial and maximum rate of p o l y m e r i z a t i o n , overall time of p o l y m e r i z a t i o n , polymer molecular mass and i t s d i s t r i b u t i o n , side r e a c t i o n s and i r r e g u l a r structures. Other r e l e v a n t parameters, such as v i s c o s i t y r a i s e and crystallization rate,which are c u r r e n t l y explored by other research groups (13,15), w i l l be the subject of future s t u d i e s on our experimental system, i n the presence of various added substances. ReteasLcfi

undo.*. Cont/iact

C./V.ft.

-

ANUC S.p.A.

sicg,.

22.12.82

Literature Cited 1.

2. 3. 4. 5.

Bonta', G.; Ciferri, Α.; Russo, S. "Ring Opening Polymerization"; Saegusa, T.; Goethals, L . , Eds.; ACS SYMPOSIUM SERIES No. 59: Washington, D.C., 1977; p. 216. Costa, G.; Pedemonte, E . ; Russo, S.; Sava', E. Polymer 1979, 20, 713. Alfonso, G. C.; Bonta', G.; Russo, S.; Traverso, A. Makromol. Chem. 1981, 182, 929. Alfonso, G. C.; Pedemonte, E.; Russo, S.; Turturro, A. Makromol. Chem. 1981, 182, 3519. Biagini, E . ; Pedemonte, B . ; Pedemonte, E.; Russo, S.; Turturro, A. Makromol. Chem. 1982, 183, 2131.

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

11. ALFONSO ET A L .

6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16.

17. 18. 19. 20. 21. 22. 23. 24. 25. 26.

Activated Anionic Polymerization of e-Caprolactam

179

Alfonso, G. C.; C i r i l l o , G.; Russo, S.; Turturro, A. Eur. Polym. J. 1983, 19, 949. Alfonso, G. C., Costa, G.; Pedemonte, Ε.; Russo, S.; Turturro, A. Proc. 5th AIM Meeting, Milan, 1981. Russo, S. Proc. IUPAC 28th Macromolecular Symp., Amherst, 1982. Kubiak, R. S.; Plast. Engng. 1980, 36, 55. Kubiak, R. S.; Harper, R. C. Reinf. Plast./Composites Inst., 35th Annual Conf., 1980, Sec. 22-C, p. 1. Hedrick,R. M.; Gabbert, D. Α. I. Ch. E. Symp., Detroit, 1981. Gabbert, D.; Hedrick, R. Μ. Α. I. Ch. E. Symp., Detroit, 1981. Sibal, R. E . Camargo R Ε. Macosko C W Int J. Polym. Techn press. Russo, S. Proc. 5th AIM Summer School on Polymer Processing, Gargnano, 1983; p. 289. Camargo, R. E . ; Gonzales, V. M.; Macosko, C. W.; Tirrel, M. Rubber Chem. Techn. 1983, 56, 774 Šebenda, J. In "Comprehensive Chemical Kinetics"; Bamford, C. H.; Tipper, C. F., Eds.; Elsevier: Amsterdam, 1976; Vol. XV, Chap. 6, 'Lactams', p. 379ff. Alfonso, G. C.; Russo, S.; Pedemonte, E.; Turturro, Α.; Puglisi, C. Italian Pat. 21912A/83 (to C.N.R.). Russo, S.; Alfonso, G. C.; Pedemonte, E.; Turturro, Α.; Martuscelli, E. Italian Pat. 21950A/83 (to C.N.R ). van der Loos, J. L. M.; van Greenen, A. A. ACS PMSE Proc. 1983, 49, 549. Biagini, E.; Razore, S.; Russo, S.; Turturro, A. ACS Polymer Preprints, 1984, 25 (1), 208. Russo, S.; et al., to be published Biagini, E.; Gattiglia, E.; Pedemonte, Ε.; Russo, S. Makromol. Chem. 1983, 184, 1213. Schuttenberg, H.; Schulz, R. C. Angew. Chem. 1976, 88, 848. Jacobi, E.; Schuttenberg, H.; Schulz, R. C. Makromol. Chem. Rapid Comm. 1980, 1, 397. Weisskopf, K.; Meyerhoff, G. Polymer 1983, 24, 72. Šebenda, J . ; Kouřil, V. Eur. Polym. J . 1971, 7, 1637.

RECEIVED June 14, 1984

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

12 Properties and Morphology of Impact-Modified RIM Nylon J. L. M. VAN DER LOOS and A. A. VAN GEENEN Polymer Chemistry Department, DSM, Research andPatents,PO Box 18, 6160 MD Geleen, The Netherlands

RIM nylon is a new development in the long­ -established techniqu -caprolactam. Fo dry non-modified nylon is insufficient. By dissolving an impact modifier (a rubber-like material, such as a polyol, with low Tg) in the caprolactam melt before polymerization the impact strength can be improved, though with a decrease in flexural modulus. The various kinds of morphology which can occur with rubbertoughening and the relation between morphology and mechanical properties will be discussed. For the ABA type block copolymers the postulated morphology is that of a continuous rubber network extending through a nylon phase, which would explain the high toughness and the low flexural modulus of these block copoly­ mers. The

anionic polymerization

polymerization in

a m o u l d b y means o f

temperature formed.

lower

With

mization

of

completed

in

For

most

the

toughness

than

choice

3 minutes

applications, for

of

nylon

of

point

of

decrease

that

in

properties of

a fairly is

polymerization

conditions

so t h a t

RIM

the polymer

old

polymerized

the

reaction

particular

i n s u f f i c i e n t . The most

brittle amount

flexural of

in

and by

opti­ c a n be

c a n be c a r r i e d

the automotive

polymers of

is

is

industry,

successful

method

rubber-toughening.

a dispersed

rubber

phase

and t e n s i l e

modified

Several

There is

kinds

nylon of

and the

an una­

strength, Is

By

(impact

improved s i g n i f i c a n t l y

modulus

the rubber nylon.

a

machine.

resistance

unmodified

system

at

to be

the polymerization

in

a minor

the fracture

of

is

is

modifying of

(CL)

caprolactam

s t r e n g t h c a n be i n c r e a s e d s e v e r a l f o l d .

voidable balance

the melting

a s p e c i a l l y adapted

incorporation impact

about

molten

an a c c e l e r a t o r and a b a s i c c a t a l y s t

than

a correct

in

modifier)

caprolactam

the polymerization

out

developed

of

technique by which

much

morphology

but

the

better which

0097-6156/ 85/0270-0181$06.00/ 0 © 1985 American Chemical Society

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

182

REACTION INJECTION M O L D I N G

can

occur with

logy

rubber-toughening

and m e c h a n i c a l p r o p e r t i e s

and the

will

be

relation

between

morpho-

discussed.

Experimental The At

polymerization a temperature

one

half

of

modifier mixed

perature was In a

the

were

and

taken this

polymerization

a flat

caprolactam while

the

catalyst

in

the

was

°C.

After

mould

other

poured

about or

the

was

catalysed with sodium

10

two

minutes

modifier

was

of

common b a s i c

lactamate

and/or

solutions

was

template

used. reaction

as

were

had a

finished

the

used

in

impact

which

the

agent

mould.

dissolved

and the

mould,

product

aluminium

was

The

the

release

the

and

lactamate,

impact

half.

into

no m o u l d

a diisocyanate

diisocyanate

in

initiator

the

100

out

the

130-160

from

carried °C,

mixture

study

potassium

were

about

dissolved

the of

runs

of

between

accelerator.

catalysts

such

bromomagnesium

The

as

lac

tamate. The

Izod

notched

modulus number

of

perties The

impact

(ASTM D-790) specially

were

rubber

of selected

distribution

was

micrography

(EM).

Fracture

micrography

(SEM)

were

cooling alloy. tion

in

liquid

The

For

Philips

EM

A

number

nylon,

dynamic m e c h a n i c a l

pro-

b y means for

by b r e a k i n g

alloy

electron

the

electron samples

sputter-coated

a Philips

electron

Pt/Pd

of

scanning

SEM

505,

micrography

after

with

maximum (TEM)

an

Au/Pd

resolu-

a carbon-

was

used,

the

microscope being

a low

glass

transition

a

300. of

polymers

soluble

were

obtained

the

They were

transmission

shadowed w i t h

are

obtained

m i c r o s c o p e u s e d was

7 nm.

large

studied surfaces

nitrogen.

replica

which

samples,

determined.

in

tried

with

with

molten

out.

The

c a p r o l a c t a m , but best

not

polymerization

temperature,

compatible

results

with

were

polyols.

Morphology Depending lerator,

on the three

Intermediate System

1

between achieved glycol

forms

This the

are

by u s i n g II"

of

of

course is

modifier as

contains

modifier

the

CH3-0-(C-C-0) -CH3

Solution

II

0CN-R-NC0 +

mixing there

n

no

the

acce-

"Figure

1").

possible. no

reaction

accelerator.

This

a methoxylated

can occur c a n be

polypropylene

+

CL +

basic

catalyst

CL

and p o l y m e r i z a t i o n is

with

(see

accelerator.

I

Because

also

the

modifier

can occur

I").

Solution

After

impact

p r o d u c e d when and

impact

("solution

the

morphologies

morphology

impact

(PPG)

"Solution

interaction

different

interfacial

only

a horaopolymer

adhesion

the

rubber

is

formed.

segregates

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

as

12. VAN DER LOOS AND VAN GEENEN

F i g u r e 1. described.

Morphology of

Impact-Modified RIM Nylon

the

various

polymerization

183

systems

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

184

R E A C T I O N INJECTION M O L D I N G

shapeless This

patches

procedure

and i s

was

System 2

By

which

reactive

mers In

are

(block

this

poorly

already

application to

copolymer)

case

of

the

distributed

described

in

an impact

polypropylene

the

nylon

phase.

(1).

modifier

accelerator

c a n be

in

1965

containing

("solution

I"),

groups

graft

poly­

formed.

glycol with

t e r m i n a l - O H g r o u p s was

used.

CHo

I Solution

I

HO-(C-C-0)£-H

Solution

II

OCN-R-NCO +

The

isocyanate

the

following

+

CL +

("solution

can react

in

either

of

OCN-R-N-C-(NC) -N-C

polymerization ~

+

W

Il H HO

HOvwOH

0

»

formation

0

U

H

(2)

0-C-N-R-NCO

urethane

HH

CL'

(1)

n

0

0 +

II")

ways:

Ν (2)

catalyst

CL

accelerator

-• 0CN-R-NC0

basic

0

II

H

H

HOa*w*o-C-N-R-N-C-(N

C) -N-C

(n

m

polymerization

^

and m

about

100

or

higher) Because only

"reaction

a minor

modifier the

segregates

nylon

acting this

(1)"

quantity

phase.

as

is of

as

The

fine

block

an e m u l s i f i e r

polymeric

'oil

considerably block

in

spheres

for

the

is

than

two

incompatible the

The

(2)",

impact

distributed

concentrates

emulsion

"reaction

formed.

homogeneously

copolymer

oil'

faster

copolymer

at

the

polymers

lnterfaclal

ln

interface, (2_).

adhesion

In is

good. A disadvantage

of

the

rubber

phase

thé

rubber

is

patent

lymer

low,

This

between is

prepared and,

by if

systems the

System 2

rubber

occurs

and

consisting

the

in

the

nylon

of

case

phase.

a rubber

is

described

of

complete

Separately,

segment

with

0 +

2 is

that

weight in

of

several

interaca

prepo-

terminal

groups.

Η

Η0*~Μ·0Η

1 and

molecular

(3-5).

morphology

the

prepared

accelerator

polymers

can even exude.

applications

System 3 tion

the

c a n be e x t r a c t e d

2 0CN-R-NC0

»

«

OCN-R-N-C-0 ~ ~ ~ w ~

0

II

Ν

0C-N-R-NC0

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

12.

VAN DER LOOS A N D VAN GEENEN

This

prepolymer

tion

in

is

dissolved

I

Prepolymer

+

Solution

II

Catalyst

CL

In

0

this of

/

copolymer is represented

\

and m this

about

copolymers

100

the

are

The

in

2A"

rubber

merization system

3. as

sion

of

is

conditions "Figure as

big

those

block

of

the

big

in

some o l d e r

N-C

(3)

the

rubber

patents

block

the

systems

1,

2

and

3

distribution

in

a

polymer

not

shows

of

small

in

a polymer

made

according

phase s e p a r a t i o n

(about

3 μ)

nylon

2B")

particles

shows (about

to

poly­ in

this

system

few

has

active

interfacial of

prepared according

("Figure

rubber

properties

the

polymer

a

The

continuous

occur

the

and q u i t e

blocks.

a

When

can also

mechanical

2

patches

micrograph). this

a polymer

system

the

optimum

form

and the

poor.

shapeless in

copolymers prepared according

continuous

network

be g r e a t e r

sequence. this

in

I

than

the

thin

(14). the

case

layers, The

this to

1 μ)

adhe­

polymer

system

a very

1.

regular

in

end-to-end distance even be

smaller,

is

about

hardly

However,

distinguishable with

system

one a t

The 3

100

("Figure

viz. Â,

a

continuous

-62

°C

3")

of

the

about

the

relaxation

to

of

200

rubber or

rubber the Â.

as

100

Â.

a

phase

stretched

Because

thickness

rubber

of

of the

the

Because

phase i n

domains

spectrum

indeed displays

owing

the

a molecular weight

about

the

3,

cylinders

the

system

3

2C").

dynamic mechanical

("Figure

about

most

stretched,

dynamic mechanical

be d e t e c t e d . by

also

thickness

at

not

SEM

be f u l l y

is

phase w i l l of

system

thin

a polyol with

chain w i l l

resolution

to

ln

end-to-end distance

of

rubber

peaks;

C

optimum;

rubber

very

premature

may b e a r r a n g e d

never

pared

II

(9-13).

rubber

can

Q

phase.

segments

is

is

p r e p a r e d by

domains

particles

equal to

distribution

is

reacted to

micrograph of

4000,

but

that 1

are

2D" of

The

rubber

shows

black

are

nearly

adhesion

polymers

s e g r e g a t e d as

(the

small

the

\

2".

system

very

nylon

°

n

b

the

to

have not

is

/

H/H

H

struc­

in

"Figure

a result

segregated groups

H

chemical (3)

higher).

mechanism (6-8)

clearly

phase

where

solu­

discussion

according

nylon

can

or

Interfacial

already mentioned

EM m i c r o g r a p h s

In

H

exude or

and

"Figure

°

C-N-R-N-C-0*AA~V* O-C-N-R-N-C + N

postulated

made

II

N f~

cannot

given

0

H

The

formula

HH

new d e v e l o p m e n t s

are

0

formed. by

H \

system

Results

is

0

(n

last

+

a polymer

In The

a catalyst

CL

a n ABA b l o c k

C

phase

and mixed w i t h

such

0

C-N-4

CL

case

/II

II

in

CL.

Solution

ture

185

Impact-Modified RIM Nylon

the

glass

of

two

of

about

100

a polymer separate

transition

of

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

Â

pre-

loss polyol

REACTION INJECTION M O L D I N G

F i g u r e s 2 a and b . E l e c t r o n m i c r o g r a p h s of f r a c t u r e s u r f a c e s of p o l y m e r i z a t i o n system 1 (a) and 2 ( b ) . F i g u r e s a and b were examined i n TEM..

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

12.

VAN DER LOOS AND VAN GEENEN

Impact-Modified RIM Nylon

F i g u r e s 2c and d . E l e c t r o n m i c r o g r a p h s of f r a c t u r e s u r f a c e s of p o l y m e r i z a t i o n system 3 . F i g u r e s c and d were examined i n SEM.

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

187

REACTION INJECTION MOLDING

188 and

one a t

about

Apparently, as

a separate An

Table

70

a block

to

the

glass

transition

copolymer the

bonded

of

the

polyol

is

nylon. present

phase.

overview

of

the

mechanical

properties

is

given

in

I.

Table I .

AP

°C o w i n g

even i n

nylon

System

1

System

2

M e c h a n i c a l P r o p e r t i e s (Measured Dry as Made)

Polyol

Izod

%

kJ/m

(wt)

(notched)

Flexural N/mm

2

-

4

3250

20

5

2420

10

9

2700

1850

modulus

2

20 System

From the

3

10

26

20

54

1370

30

60

420

the t a b l e

it

interfacial

appears

the

that

Izod

adhesion increases.

recent

p u b l i c a t i o n about

nylon

6.6

maleic

anhydride

(15).

Addition

(30

%)

affords

the

flexural

than

in

the

of

above

the

transition

the

modified

nylon).

The

the

strength and/or This

the

is

20

of

This

small

2,

of

we p o s t u l a t e is

in

the (E

soft -

the

they

mainly

by w h i c h bands

crazes is

from

the

case

the of

phase

less

of

lower

shows

at

due a

the

to

tem-

phase and below

flexural of

4

(E/Eo)

modulus

of

unmodified fit

fairly

are

difference

is

3

but

prediction

Fig.

1 and 2

that

system

already

the

in

a hard matrix

The 2

in

well

wellin

Impact

due t o are

the

better

stabilized

initiated. theoretical

a higher

for

curve.

example

rubber

content,

reversion.

that

network

and t h e r e f o r e

the

that

a nylon

the

modulus

systems

shear

phase

as

a

toughness,

for

an anomalous s t r u c t u r e ,

or,

state

in

halved.

the

proves

inclusions.

system

than

modulus

1 and system

in

line

phase

flexural

points

of

networks

through

rubber

copolymers is theory

of

3 deviate widely

fraction

included

hard

improves

concluded

The

phase i n region

of

% impact modifier

rubber

»

of

of

system

more

more

(16-18).

formation

intermediate

extending

the Q

without

an i n d i c a t i o n

Therefore,

is

reduction

curve.

a d h e s i o n of

interlocking an

of

and E

between system

points

ABA b l o c k

rubber

experimental

interfacial The

region

systems

in

transition

theoretical

dispersed

the

a soft

nylon

of

have g i v e n a b a s i c

for

the

strength

also

compounded w i t h p o l y e t h y l e n e - g -

system,

a composite

curve

incorporation perature

of

which

rubber

authors

is

any a d d i t o n a l improvement

modulus,

modulus

theoretical

onto

hardly

a dispersed

Several of

polymer

impact

This

morphology of an almost ("Figure

will nylon

be more

system

continuous 5").

By

perfect.

can contribute

3,

with

rubber

increasing More to

the

nylon

about

network the is

modulus.

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

12.

VAN DER LOOS A N D VAN G E E N E N

189

Impact-Modified RIM Nylon

F i g u r e 4 . Modulus r e d u c t i o n as a f u n c t i o n of the s o f t rubber phase volume (temperature 23 ° C ) . Key: • , system 1 ; O , system 2 , and #, system 3 .

Figure

5.

P o s t u l a t e d morphology

of

ABA b l o c k

copolymers

(system

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

3) .

REACTION INJECTION MOLDING

190 The

net

effect

Furthermore, by

the

nism

rubber

will

plastic

no

ot

during

concluded the

Is

phase,

place

testing

in

true,

observed, which

of

is

that

flow.

This

m e c h a n i s m by means o f From

these

3 with

accordance

with

was

volume

experiments

20

a n d 30

c o m p l e t e l y due to

in

mecha-

expect

by s h e a r

system

was

determined

deformation

one would

(19,20).

products

deformation

so

be l a r g e l y the

mainly

deformation

tensile

plastic

c r a z i n g was

take

the

modulus.

this

rubber

will

that

in

behaviour w i l l

If

the

by a n a l y s i n g

% polyol

drop

properties.

be t h a t

monitoring was

a sharp

deformation

deformation

verified it

is

the

shear

the

weight flow;

morphology

postulated. Another

consequence

ties

the

of

system

of

Consequently,

a high

in

with

accordance

obtained

this

are

morphology is

largely

elongation at

the

high

that

d e t e r m i n e d by

Izod

break w i l l

values

of

the

ultimate

those

of

the

be a t t a i n e d .

the

ABA b l o c k

properrubber. This

is

copolymers

experimentally.

Conclusions -

Improvement

by

shown,

the

although -

It

with

the

is

postulated

20

% or

more

through

because

that

the

polyol

is

further

additional

is

RIM

that

of

in

of

of

highest

loss

in

ABA t y p e

the

rubber

achieved

morphology toughness,

flexural

deformation

modulus.

block

rubber

copolymers network

behaviour phase.

and

Improvement

flow.

content the

c a n be

kinds

a continuous

the

shear

polyol

perfection

the

morphology of

phase,

nylon

various

by a great

due t o

a high

improvement

decreases

of

the

b e i n g d e t e r m i n e d by

strength

A p p l i c a t i o n of

Of

copolymers possess

a nylon

strength

impact

impact strength a polyol.

accompanied

is

ultimate of

of

ABA b l o c k

this

extending

-

of

incorporation

(30

rubber

%)

is

network

impact strength,

while

not

interesting,

yields the

little

modulus

sharply.

Acknowledgments The

authors

for

his

for

their

wish

to

interest

electron-microscopy tion

of

express

experimental work,

samples

their to

and h e l p f u l studies

under

his

Dr.

a p p r e c i a t i o n to F.

Maurer

discussion,

and to

Mr.

Mr.

and Dr. to

Mr.

C. Vrinssen

J.

S.

S.

Bongers

Sjoerdsma

Nadorp for

for

the

guidance.

Literature Cited 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11.

his

examina-

Courtaulds, G.B. Patent 1126211 pr. date 1-14-1965 G.E. Molau, J . Polym. Sci A3, 1965, 4235 DSM/Stamicarbon, US Patent 3704280 pr. date 3-25-1969 DSM/Stamicarbon, US Patent 3770689 pr. date 1-24-1970 DSM/Stamicarbon, US Patent 3793399 pr. date 9-23-1970 Monsanto, European Patent 67694, pr. date 6-16-1981 Monsanto, European Patent 67695, pr. date 6-16-1981 DSM/Stamicarbon, patent applications to be published ICI, GB Patent 1.067.153, pr. date 5-17-1963 British Celanese, GB Patent 1099265, pr. date 5-11-1964 Toyo Rayon, Japanese Patent 16028/69, date 7-15-1965

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

12.

VAN D E R LOOS A N D VAN G E E N E N

Impact-Modified RIM Nylon

12. Monsanto, US Patent 3862262, pr. date 12-10-1973 13. Monsanto, US Patent 4031164, pr. date 8-25-1975 14. M.J. Folkes and A. Keller, Physics of Glassy Polymers, Appl. Science Publishers, 1973, Ed. R.N. Haward Chapter 10 15. S.Y. Hobbs, R.C. Bopp and V.H. Watkins, Polym. Eng. Sci. 1983, 23, 380 16. E.H. Kerner, Proc. Phys. Soc. London 1956, B69, 808 17. C. van der Poel, Rheol. Acta 1958, 1, 198 18. L. Bohn, Copolymers, Polyblends and composites. Advances in chemistry series no. 142, 1975, Ed. N.A.J. Platzer, Chapter 6 19. C.B. Bucknal and D. Clayton, Nature (Phys. Sci.) 1971, 231, 107 20. D. Heikens, S.D. Sjoerdsma and W.J. Coumans, J. Mater. Sci. 1981, 16, 429 RECEIVED

April 16, 1984

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

13 Self-Releasing Urethane Molding Systems: Productivity Study LOUIS W. MEYER The Dow Chemical Company, Freeport, TX 77541 This review identifies the primary reason for utilizing self-releasing urethane molding systems: increased productivity In achieving this goal however, the practica features, whic must be recognized, understood, and dealt with. For example, the need to paint parts is most often a very real and critcal issue which must be effectively worked out when using self-releasing systems. Theory relates release in terms of the equations defining adhesion, especially work of adhesion, Wa. What is sought is minimum adhesion and this is achieved by an IMR agent acting as a low energy film barrier between the mold metal high energy surface and the moderate (polar) energy surface of the urethane system itself. To date self-releasing systems have not provided infinite cycles of release, yet the number of consecutive releases for molds of differing degrees of complexities result in significantly improved productivity - the range being between 25% to 140% increased production yield. Cost reductions in manufacturing operations using IMR systems should be coupled to productivity increases. Typically, a 50% increase in productivity should show a cost reduction on the order of between 15% and 20%. The technology of self-releasing systems based on IMR agents is both new and incomplete in total development. Probably much needs to be done in terms of refinement and further extension of use, yet the overall benefits of a system which can be termed "effective" are of considerable practical value, even now. 0097-6156/85/0270-0195$06.00/0 © 1985 American Chemical Society

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

REACTION INJECTION MOLDING

196 Mold

release

requirement parts

cannot

release

by in

fact

the

press one

that in

need

urethanes, are

to

the

who

molding

effective

in

operation

spray

apply

a

cost

as

external

and

this

example, if

seconds

in to

it

This

is

turn

is

$.05

release

sprays

four

leads

hours,

"time-out" out

to

is

condition

1 hour 12.5%

loss

the

with

productivity

The of

in

external

possible

by

polyurethane least, The

25%

internal

mold r e l e a s e

backs.

use

is

not

required in

to

cycle

time,

more

loss.

Increased

Reduced manufacturing

production

3.

Improve

a total costs

loss

an i n t e r n a l

akin are

to

12.5%

of

37.5%

are

directly

to

is

further

not

always

inherent

in

mold r e l e a s e

external

release based

agent or

in at

methods. The on

effective

efficiency, cost,

production

use

made

eliminating,

and r e a l .

system

the

system,

are:

optimizing

and

go down.

quality.

a d d s up

lost

it

Optimization.

way o f

distinct

cuts

this

ignored.

costs

while

certainly

a possible

If

variables

Production

every

typical,

increases,

a self-releasing

agents

is

on

use

additional

again,

time.

A self-releasing

of

as

This

Combining t h i s

in

quality,

are

and sprays

necessitating

operational which

even

cleaning

excessive

often

common.

in

observe spot

waxes

addition,

important

of

part

problems

1.

devoted to

c a n n o t be e a s i l y

two

way,

reduction

conditions,

shift,

sprays.

from of

a 25%

uncommon t o

and m a n u f a c t u r i n g

section

2.

which

time

is

draw

Its

be done as

results

c a n be r e a l i z e d

part

every

release In

process

that

incorporation

derived

of

loss

surrounding

the

not time

When p r o d u c t i v i t y

benefits

All

of

is

hour

chemicals offers

which

a

between

available production

a value

mold r e l e a s e

minimizing

gains

mold

a spray

The

mold b u i l d - u p

each 8

a quantitive

the

molds

done by

numerous

agent, is

may h a v e t o

make t h e

subject

problems

the

overcoming

normally

efficiency

external

between these

the

has

cycle.

a shift

efficiency

related.

identified

to

of

overall,

in

it

It

machine u t i l i z a t i o n

relationship

discussed

once

previous

Production indirectly

This

otherwise

out

represent

The

"dirty"

up.

of

to

of

achieving release

part.

because

production

although

a portion

time

losses

the

mold c l e a n

is

of about

composition,

stick

and w a s t e f u l .

release

mold and a p p l i c a t i o n of

total

aid

brought

apply an e x t e r n a l

form of

wasted

be o b s e r v e d .

of of

seat

the

a 12

would

mold during

to

effective

negativel

in

productivity

the

to

the but

Is

s u c h as

chemical

like

molded

without

compounds i s

This

per

higher the

is

critical RIM

without

their

method of

apply an e x t e r n a l

productivity

in

b o t h messy

much as

spray

tools

common p r a c t i c e s

surface.

technical sense,

-

For

The

urethane

mold

of

and

process.

tools

urethanes

formed.

applies

The

their

because

Thus,

cycles.

molding

mold r e l e a s e

problem of

agent

without

their

molding

foam molded a r t i c l e s

for

nature.

articles

operator

or

been an important

urethane

Likewise,

The

"sticking"

release

of

c a n n o t be removed f r o m

adhesive which

have always type

be removed f r o m

agents.

the

are

any

agents*

cushions, such

agents of

performance.

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

13.

Self-Releasing Urethane Molding Systems

MEYER Commercial

IMR P r o d u c t s

It

that

appears

agent

the f i r s t

came a b o u t

defined

this

product

have

deleterious

been

limited

the introduction

through

which

commercial

is

effects

agent

products

-

release

on t i n c a t a l y s t s . t h e amount

and adding a t h i r d this

is

of an e f f e c t i v e

of a product

dimethylsiloxane

an e f f e c t i v e

to increasing

the system,

Systems

commercial promotion

through

as a c a r b o x y - f u n c t i o n a l

Although

of

and Self-Releasing

197

of

-

it

Practical

is

to

i n the B-side equipment

The i n t r o d u c t i o n

has to d a t e ,

prone

use has thus

to the process

Introduced.

a s IMR a g e n t s

fluid (1)·

agent,

tin catalyst

stream

IMR

chemically

of

other

n o t been

evident. In

an abstract

approached an a l l the

polyurea

system

gleaned, show

of an unpublished

the question

from

the u t i l i z a t i o n

fluid

Specifics

employed. t h e work

p a p e r , Dominquez

mold r e l e a s e

(2)

by making use of

a r e not a v a i l a b l e on e i t h e r

Further

I n f o r m a t i o n may b e

of Plevyak

and Sobieski

(3).

They

o

i n a two s t r e a m

system

which

A which

is

a l l polyurea.

self-releasing had been

added

the

aromatic

quasi-prepolymers

product

I.

+

Extender

Isocyanates

IMR a g e n t w h e n

for Internal

Amine

Type

Modified

Aromatic

Mold Release

Mondur

Tin

Fomrez

^Trademark

of Rubicon

^Trademark

of A i r Products

5Trademark

of Witco

(Reproduced w i t h

Chemical Chemical

(2)

permission

(5)

Index

PF

(3)

(4)

1.03

191 LF-179

33LV UL-28

0.10% 0.15%

Company Company

Chemical

Company

Company from R e f . 4.

Copyright

M

(PBW)

18-24 (1)

I .

(4)

Company

Chemical

Chemical

System

100

Dabco

o f Mobay

"Table

Quantity

Rubinate

o f Upjohn

in

Designation

Amine

^Trademark

andmolded

XA-10888.00L Isonate

prepolymers

^Trademark

shown

DETDA

Amine

Quasi-

Catalysts

is

to

with

(DETDA) a n d

exceptional process systems

polyol

formulated

diethyltoluendiamine

The formulated

Generic

IMR-II

o n a n amine m o d i f i e d

demonstrated

Formulation

Item Polyol

based

amine c h a i n e x t e n d e r

attributes.

Table

system

a proprietary

MDI

Chain

internal

system.

o r IMR a g e n t

however,

of

1983, SPI.)

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

REACTION INJECTION MOLDING

198 Particular

attributes

characteristics; catalyst

reactivity,

exception which

release

had no

In

to

crucial

formulated the

the

chemicals should

are

It

the

nature

Polyol

is

of

the

that

other

A brief

a

tin

for

metal

molds

features

highly

desirable

of

review the

a

of

which

are

fully these

value

or

worthiness

whole. and o f t e n

physically

system.

This

mandatory

that

and c h e m i c a l l y w i t h

means

that

the

IMR

the

agent

o of

Reactivity: normally

In

added

chemically inert

incorporated

their

in

the

the

catalytic

reactivity

compounds

induce

example,

the

about

this

adding

a

remain

separate

problem

third a

stream

molding

components.

B-side is

this

IMR

This

not

or

in

agent

operation

seriously

this to

until

is

of

tin

active are

IMR ln

a

totally

catalysts

the

to

make c e r t a i n

reduced.

IMR Not

catalyst,

always the

equipment

r e a c h the

operation,

but

agent all

IMR

fluids

way o f or

IMR

this

the

use

agent.

a n d IMR

head.

to

minimizing

catalyst

catalyst

For

tend

through

of

also

some d o .

Is

the

Is that

true)

mixing

free

are

If

A possible

not

either

the

they

stream

By

agent

Ideally,

"catalyst

k i l l "

preferable.

Bleed-Out: in

the

Freedom from e x u d a t i o n

molded a r t i c l e

is

also

or

bleed-out

be a c r i t i c a l

of

factor

performance. pheonomena, if

self-evident.

tape

and p a i n t ,

for

however,

this

in

example, w i l l undesirable

Raw m a t e r i a l

compounds w h i c h polymer

present

Adhesive qualities

part,

avoided.

active IMR

important

degrading e f f e c t .

stream

two

agent

overall

it's

problem on

addition

remains

Exudation

are the

an

which

isocyanates.

carboxy-functional dimethylsiloxane

stream

however,

who

with

toward

B-side

problem (although

third

products

those

form.

a two to

compound h a v i n g

compounds t o

and i s o c y a n a t e manufactures and s t a b l e

have

parts

assessing

as

is,

compatible

IMR

to

are

system

choice

supply

be

RIM

stable

importantly,

and u s e f u l n e s s

isocyanates with

technology

to

there

system.

important

urethane

limits

non-reactive,

the

se,

be c o m p a t i b l e , b o t h of

hydrogen,

this

and most

be c o m p a t i b l e w i t

reactive

of

per

chain extenders),

bring

a n d 300

outstanding

retention,

coat.

adaptability

self-releasing

agents

plus

b e t w e e n 25

self-releasing

Compatibility; IMR

nucleation,

wax b a s e

release to

characteristics of

example, these

Features

addition

often

for

physical properties

stable

-

prior

Performance

include,

stable

are

solubility

to

molded p a r t , materials

be v e r y

feature

manufactures either;

the

(1)

will

poor.

will

s u c h as For

the

most

c a n be c o n t r o l l e d usually

select

which

are

free

or

only

isocyanate reactive,

characteristics

usually scotch

of

or

those (2)

this

problem.

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

13. MEYER

Self-Releasing Urethane Molding Systems

Physical should

Property

urethane

polymer.

plasticization usually

evident

that

There

IMR a g e n t s

is

most

must

often

IMR-II were

Table

in flexural

seen

Is

shown

through

i n "Table

essentially

property

II.

Physical

Property

Plasticization

a significant These

-

reduction

data f o r three low results

by the a d d i t i o n

non-existant

show

of the release

a good

indication

of

Without

C

Β

A

100 p t s

and

(4)

Amine

Amine

Conventional

Modified

DETDA,

pts

21

18

18

Mondur

PF 1.03

53

60

60

28,650

30,000

30,800

3,600

2,800

2,900

265

280

290

280

480

490

Index,

is

while

Comparison o f Systems W i t h

Formulation Polyol,

either

modulus,

I I " ·

systems

of the

stability.

IMR

Type

of

i n molded p a r t s .

Comparative p h y s i c a l property

RIM s y s t e m s

product

properties

be no e v i d e n c e

changes i n p h y s i c a l p r o p e r t i e s

agent

in self-releasing

the the physical

by a r e d u c t i o n

elongation.

modulus

affect

or embrittlement

embrittlement in

Retention:

not adversly

199

pts

Property Flexural Tensile

Modulus, Modulus,

psi psi

Elongation, % Tear

Strength,

Heat

Sag,in.250°F/

60

p l i

min.

6

i n . overhang

0.57

0.51

0.53

4

i n . overhang

-

0.29

0.31

Specific

Gravity,

(Reproduced with

g/cc permission

Many RIM f o r m u l a t e d or

other

thermal

kinds

this

This

is

is

done,

expected.

Therefore, toughness

about

words

andincrease

The r e d u c t i o n ,

however,

should

by f u r t h e r

t h e bond s t r e n g t h lowered

plus

not bring

between f i b e r

formulation

Β of "Table

II"

1/16

inch milled

fiber

the f l e x u r a l

and

the reduction i n "Table

glass

in

fibers, linear

rigidity.

always

evident.

n o t be d r a s t i c . in a

additional

formulated

loss

in elongation. andpolymer

IMR a g e n t s .

was m o d i f i e d

i n e l o n g a t i o n was o n l y

is

IMR a g e n t

reduction

by the presence of

glass

part

should

about

when

shown

milled

i n elongation

system

1983, SPI.)

a reduction

some r e d u c t i o n

as evidenced

critically

Copyright

Incorporate

any combination of f i l l e r

self-releasing

be

also

to bring

expansion andc o n t r a c t i o n ,

When

other

from R e f . 4.

systems

of f i l l e r s

1.02

1.00

1.01

in In

should not

For example,

b y a 10% a d d i t i o n

modulus slightly

nearly more

of

doubled,

than

III".

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

30% a s

200

REACTION INJECTION MOLDING

Table

III.

Effect

of

IMR

Plus

Milled

Physical Formulation Glass Neat

Loading* Flexural

Flexural Tensile,

Heat

psi

psi

Β

C 10 30,800

54,200

53,800

2,750

2,800

198

200

511

532

%

(250°F/60 min),

Reinforcement

10

pli Sag

Fiber

30,000

psi

Elongation, Tear,

Modulus,

Modulus,

Glass

in.

6

inches

overhang

0.30

0.20

4

Inches

overhang

0.25

0.21

1.09

1.11

Specific *737

Gravity,

A A Owens

parallel

to

Likewise,

when

the

by

loss

measure

of

Most for

cost,

realizable

such as system

air

or

structure

or

The

concern.

the or

remained i n t a c t , of

These

tear

RRIM

as

evidenced

strength -

results

or

Poor

are

a

also

good

shown

in

by

incorporating of

to

part

w h i c h makes

either

with

a blowing

therefore, stability

these

a

gas

agent

not

in

affect

nucleated froth:

emulsified

-

of

(paint).

problems

eyes, to

It

phenomenon o f the

the

it

of

the

the

must

the

brings

wet-out

is

(molded p a r t

difficulties

of

the

a liquid the

solid X

on

the

surface

of

those

liquids.

•

yields

value

of Y

to

the

sc.

the

a liquid

be r e l a t e d agents;

in

which

is

e y e , and orange

to

the

and of

(thus

the

well.

surface liquid will

wet

this liquid

to

plot

to

it surface

vapor

liquids

surface value

surface

spontaneously

usually

various

the

not

related

C5)

an e m p i r i c a l parameter the

of

peel

the

critical

against

such

and

when a l i q u i d

c o n t a c t angle of

of

possess

of

and co-workers as

one

a d h e s i o n as

property

occur

question the

to

wet-out

paint

to

is

terms

great

fish

he d e f i n e d This

of

poor

Zisman

c o s i n e of

solid

must

IMR

surface),

tend

Extrapolation se,

are

spread on a s u r f a c e

property

by p l o t t i n g

to

related

of to

always

about

lead

the

ability

described in

like

can usually

s p r e a d on a s u r f a c e .

effectively)

painting

p r e s e n c e of

can also

solid

Wet-out

of

and the

effectively

0°)

the

density

and improved

structure

agent must, the

are nucleated.

reduced

by n u c l e a t l o n ,

stability

wet-out

problems.

tension

as;

mold f i l l i n g ,

difficulties

relative

adhesion.

obtained

things

microcellular

hinder

fish

Painting

things

tension

of

A n IMR

elusive

orange p e e l ,

lv

of

system.

Painting:

The

properties

processed systems

such

achieved

nitrogen,

subtract

nucleated

paint

The is

formulation.

neither

RIM

include

increased ease

apppearance.

two

polymer

and r e t e n t i o n

urethane

this

benefits

as

the

bond s t r e n g t h .

surface

cell

glass

III".

reasons

lower

of

elongation

retained

Nucleation: The

milled

formulatio

toughness

of

"Table

1/16"

flow.

fiber, low

g/cc

Corning

on

Properties

tension COS

s

tension

s p r e a d on

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

that

1

13. MEYER

Self-Releasing Urethane Molding Systems

surface. Paint

An example of

problems,

surface

tension

surface

t e n s i o n \f s c o f

For surface value

of

the

the by

coating. will

ο lv

of

part,

This

(1)

by

IMR

the

agent.

T y p i c a l methods

degreasing, Paint

of

post of

or

the

less

the

than

molded

tension,

were

free

Figure the

critical

part. agent

also

making i t

of

the

the

cure)

to

the

part

to

paint

power wash s y s t e m s

the the

surface one of

two

formulation

surface,

or

(2)

remove r e s i d u a l

cleaning include;

on

lowers less

IMR

c a n be s o l v e d by e i t h e r

solvent

1.

vapor

a n IMR

solvent

by

surface wiping,

which u t i l i z e

that IMR

vapor

both

solvent

cleaners.

by s o l v e n t or

bleed

selection

of

"bite",

of

wet-out,

is

also

a n d ' p o s t molded freedom from

IMR

out

a solven

properly

addressed in

order

to

minimize

this

paint

adhesion deficiency.

topic

further

is

in

liquid

self-releasing,

adhesion although a factor

controlled exudation

it

shown

presence of

surface

if

agent on

(after

and water

and e m u l s i o n

of

is

when

near

the

however,

addition

the

part

are

systems

problem,

solubilize

occur

surface

than

washing

the

the

critical

paint,

the

to

w h i c h makes i t

solid's the

relationship

tend

paints

self-releasing of

wettable ways:

this

therefore

201

type

of

eliminate,

d i s c u s s e d under

the

or,

section

at

the

very

least,

Some o f

titled

this

Theoretical

Considerations· From the

ease

Finding to

of

the

foregoing

by w h i c h

each

IMR

agents

a compound w h i c h

provide

the

impossible.

Each

formulation of

property

-

suppliers

Theoretical

of

is

to

it

thus 1.

is

system

must

into is

obvious

only

that

curtailed.

any and a l l

perhaps

have i t s

accomplished

raw m a t e r i a l

quite greatly

systems

realistically

own

"right"

by a l i m i t e d

number

chemicals.

Considerations

sticks

to

doesn't the

be a c h i e v e d ,

urethane

self-release

far

urethane

When a m o l d e d p a r t that

so

it

selected is

c a n be "dumped" of

and e v e r y

a task

topics,

are

systems

release,

mold)

is

a d h e s i o n must

there

are

-

ability

the

one of

four

essential

adhesion.

be p r e v e n t e d . factors

which

problem (the Thus,

For

if

fact

release

most

molded

can affect

adhesion,

release: Wetting

(5)

The

of

the

liquid

polymer

to

"wet"

the

degree

the

mold · 2.

Spreading liquid

3.

Of

-

liquid

Complete "wetting";

spreads

Covalent Bonding the

4.

(5-6)

polymer

-

(7_)

system

to

in

Bonding

the

Hydrogen Bonding

(8)

-

polar

the

mold

these

polymer

to

phenomena,

spreading,

a n d two

bonding.

The

two

adhesion,

are

best

two are

are

"wetting" mold

ease

or

mold.

by d i r e c t

chemical

reaction

surface.

Bonding

by a s s o c i a t i o n of

the

highly

surface.

physical

chemical

the the

-

in

nature

-

wetting

and

c o v a l e n t bonding and hydrogen

broad c h a r a c t e r i s t i c s ,

p h y s i c a l and

chemical

examined s e p a r a t e l y .

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

of

REACTION INJECTION MOLDING

202

of Various Liquids on A Specific Solid

Figure 1. Method to determine the c r i t i c a l surface tension of solids.

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

13. MEYER

When a l i q u i d a

material

c l e a n mold and c o n t a c t s

mentioned

all

easily

plate,

or

of

metallic Not

with which

the

wetting

s p r e a d i n g of

level at

(a

of

the

initial

thickness)

metal/liquid

now e s t a b l i s h e d reactive

to

direct

altered

or

In being this

the

film

interface promotes

which about

new f i l m

chemicals,

The

of

forces.

In

those

direct

of

s e p a r a t i o n Fs Rutzler

(9) are

imperfections. Fs

system

and are

shown

the

of

a nearly

physical film

cure

ease

complete

molecular

characteristics characteristics

interface,

the

part,

the

is

chemical

adhesion to

bonding

the

be a

that

are

no

longer

which

very

These

system.

(10).

the

low,

a point

I.e.

brought

however,

wetting

not

of

system

only

this

of

a c t as

a

and s p r e a d i n g

well. for

adhesion/release are referred

however, bond.

they In

that

the

variables

as

any e v e n t ,

bond

of

of

that

the

two

force d.

of

related

about

that

work

Taylor is

is,

of

factors;

separation

only

because

are

secondary valence be p r i m a r y ,

separation

force

condition,

to

can also

be a f u n c t i o n

of and

also

1% o f

the

geometrical by

"Equation

1":

(1)

showed

of

this

that

e q u a t i o n was made b y K r a u s

for

release passed through

Under

to

addition

(.01)

refinement They

of

impervious In

non-reactive with

the

usually

to

essentially

the

agents,

d i s t a n c e of

a bond

is

d Further

-

point

they

practical fact

Wa

=

point

energy the

and s p r e a d i n g must

alter

as

chemical

Is

in

high but

so

release

responsible

and the by

the

to

nickle

wetting

chemically

they

h a v e shown

complicated surfaces

is

many c a s e s ,

a d h e s i o n Wa,

are

"wet",

to

reduce

chemicals of

energy is

but

the

intermolecular,

aluminum,

adhesion via

to

urethane

ar

Internal

forces

of

interface),

bond

barrier,

properties

Thus,

liquid

barrier

minimum v a l u e . physical

excellent

to

liquid

adhesive

at

enters

externa

the

thus

these

occurs

controlled

( a new f i l m by

With

then

properties

and i n s t e a d

"wet"

to

system

previously

compounds t e n d

they

easily

"spreads"

interface.

bring

general,

barrier

the

because

they

the

The

steel,

substantially

otherwise

detriment,

wetting

and i n d i r e c t .

non-sticking,

be t h e y

are

of

polar

an optimum c o n d i t i o n

chemistry,

maximized both

in

high

surfaces, only

all

develop.

fairly

metal molds,

surface materials.

a r e a c t i v e urethane

surfaces,

quickly

which are

"wet"

other

like

its

adhesive forces

chemicals, very

203

Self-Releasing Urethane Molding Systems

thin

layer

and Mansar

adhesive systems

a maximum v a l u e w h e r e

Fmax *

the 1.46

force Fs.

condition: Fmax =

1.46

Wa

(2)

(.01)

d Direct

measurements

summarized by K r a u s s reasonable shown energy

later

accuracy in

systems

on

the

for

"Equation where

work

(11).

systems 3".

of

Values

of

free

The

Fmax e x i s t s

a d h e s i o n Wa h a v e a l s o Wa a r e of

direct

separation has

also

been

calculatable

chemical

bond

distance d for

been estimated

high

by McKelvey

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

with

as

is

204

REACTION INJECTION MOLDING

(12)

a t about

4°A. Estimation

conditon

to c a l c u l a t e Fs

probably

on the order

solid-liquig 300

systems

ergs/cm ,

condition oxide

d for

of 20A°

of

high in

the values

be

nearly

on

the order

of

30 t o 50 e r g s / c m

of

the force

of

separation

adhesion,

yield

Case

1.

these

High

energy

Case

=

30

a

is

(Case 2)

the

thus

Young -

Wa - T t e

both

good

0.00150

10

= Y lv

χ

surface

dynes/cm

8

dynes/cm

8

(Good

2

which

is

surface,

also no mold

2

a mold

release

has been a l t e r e d

to that

bond i n t e r m o l e c u l a r

contribute

equation

liquid

for

t o a much l o w e r

high

through

energy

of

distance release

the use of

surfaces.

It

-

wetting

surface

factor

3 to 4,

( C O S JS2£

t o 4 ) Ylv

to the

(degree of

complete wetting)

(6)

also

and that

+ Ylv

to 4) + 2

=

showed t h a t ^

by Harkins

the liquid-vapor 1.0).

tension

the l i q u i d

solid

factor

The studies

about

(3

(3)

vapor

spreading

exceeds

(3

i . e .

release)

By making u s e of

energy

factors

always

approach zero Wa -

adhesion,

o f Bangham a n d Rozouk

of

10

( 1 + COS # )

3 8

v a l u e , Τ Γ e >-0.

factor

1.095 χ

to low energy

• contact angle of

+ COS 0 )

thatlTe

no mold r e l e a s e .

w i t h mold r e l e a s e ,

and the high

(5)

* e

work

-

o f Wa u s e d a r e c o n f i r m a b l e

Ylv

+

#

The

value,

Calculation

follows:

Ylv

Ylv(l

(.01)

f t

significant.

Dupree

Wa a s

where,

tension

energy.

(OH)

surfaces, can

8

the high

The values

relates

a

(Poor

low energy s u r f a c e ,

increased,

functional

2.17 p s i

difference

value.

under metal

good a d h e s i o n and poor

surface,

equivalent

£.01) -

20x10"

agent

two c a s e s ,

energy surface

release.

The

surface

surface

200 t o

release))

(300)

approximately

=

of

of

o r more

low energy

is

1,588 p s i

2. High

Fs

hydroxyl

these

energy

example, with

Wa f o r

(metallic)

poor

(1.46)

-

high

systems

for

for

results;

adhesion, Fmax -

as f o r

hand,

as low as the l i q u i d

interface

F o r many h i g h

a s 400 e r g s / c m ,

hydrogen bonding, On t h e o t h e r

film

The range

o f Wa a r e o n t h e o r d e r

conjunction with

systems.

different

possible.

to 100°A.

a n d c a n be as h i g h

surface

liquid

of

are also

Ylv

e always has

and co-workers

surface

tension

the contact angle

This (1 +

(8)

tended

by a to

being so: COS^O (5

to

6)

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

showed

13.

MEYER

If

Ylv

Self-Releasing Urethane Molding Systems Is

Further, one be

say

if

Which has

the

mold s u r f a c e

(1

for

generally

show

effective

been

to

this way

materials about

as

metal,

360

but

ergs/cm . 2

rather

spreading

them,

some l o w

a low

factor

i.e.

they

characteristic at

for

urethane

are

energy

e

energy

systems,

would

three

to

polyethylene,

in

types

a

of

free

very

plastics;

and p o l y p r o p y l e n e . surface

are

also

Materials

urethanes

different

surfaces.

which

are

self-releasing.

relative

least

low

energy materials,

have a d e f i n e d c r i t i c a l

30

vapor

relationship

observed that of

include

all

urethane is

to

(4)

polytetrafluoroethylene,

liquid

not

example, the

Dupree

surface

from adhering

than

is

Wa =• 3 0 0

C0S#)

+

Young -

on the

which

then

therefore:

is

cured

dynes/cm,

oleflnic

=Vlv

Wa

It

the

instead, zero,

60

205

tension

These

sc

less

dynes/cm surface

systems,

tensio

then

the

work

of

a d h e s i o n as

g i v e n by E q u a t i o n

4

follows:

Vlv

Wa -

(1

+

) = Vlv

0 2

=

30

the

value used

The

problems

are

similar.

Kaelble

ergs/cm in

of

provides

of

the

ionic

isocyanate,

not

too

or

other

Thus,

to

surfaces

a be

possible

metal

-

likely, or

minimize

by an I n t e r f a c e

adhesion,

present.

Production Increased

or It

which

In

terms

metal

an e x t e r n a l of

adhesion the

not

of

only

are

physical chemical

non-reactive

and the

whether

this

(EMR)

mold r e l e a s e

mold

as the

releasibility,

mold r e l e a s e

hydroxyl

polyol.

a reactive

non-polar,

mold s u r f a c e

an i n t e r n a l

avoids

of

therefore,

such

polyurethane Is

achieved

agent,

(IMR)

.

the

metal

such

A

bonding,

and/or

materials

which

a non-wetable,

film.

with

by

(40-80)

chemical

chain extender

chemical

those

about

directly

standpoint

shown

hydrogen bonding with

makes no d i f f e r e n c e

of

incorporation

but

i.e.,

between the

application

the

of

modes of

be p r o t e c t e d f r o m p o l a r

layer

boundry

via

bonding

have been

layer

hydroxide

or

eliminate

as w e l l ,

boundry

two

either

polyurethanes nature

2.

hydroxide

of

of

Case

mold s u r f a c e s

functions must

problems

metal

have a s u r f a c e

Such a surface reaction

example of

Typical to

(J)

the

adhesion viewed from a chemical

or

must by

though

the the

agent.

Optimization efficiency

reduced

If

gains

shorter

molding

automatically

are cycle

follows

starts to

with

b e made

the in

place

molding c y c l e .

production

is

the

as

a consequence

where of

It

optimization this

must

optimization. is,

starts.

increased

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

be A What

REACTION INJECTION MOLDING

206

productivity economic part

-

-

the y i e l d

factor,

the q u a l i t y

Cycle

Efficiency:

which

should

cycle

is

ta

-

ts

T h e number

better

by cost surface

reduction

-

appearance

the

of

of

consecutive self-releasing

the

cycles

to reach a p r a c t i c a l yet e f f i c i e n t

calculable.

+

followed

often,

factor.

be a t t a i n e d

readily

to -

factor,

a n d , most

This

may b e d o n e b y t h e

molding

"Equation;

ts

(5)

η where:

ta -

average cycle

to

original

-

ts

time

s

required

η = number

of

release This

cycle

time

for

time,

η consecutive

releases,

(n l), e

to apply external

consecutive release

mold r e l e a s e

spray,

between e x t e r n a l

mold

spray.

equation expresse

effective time

molding

required

system

containing

molding shonw

cycles.

a n IMR a g e n t

ts,

for

derived

i n Figure

releases

as c a n be seen

2.

Typically,

a r e needed in

as a b e n e f i t

η consecutive

A generalized relationship

graphically

consecutive cycle

cycl

t o a p p l y EMR s p r a y

between t a and η only

to dramatically

"Table

from a

self-releasing about

is

10

improve

the molding

IV".

T a b l e I V . R e l a t i o n s h i p o f the Average C y c l e Time f o r η C o n s e c u t i v e R e l e a s e s t a , and the Number o f R e l e a s e s Between E x t e r n a l Mold Release Spray η TIME

(SECONDS) Releases

Time

In

η

to

ts

ta

120

30

120.0

1

120

30

93.0

10

120

30

90.3

100

120

30

90.0

O O

a paper by T a y l o r

(13), e t .

a l . this

been extended to r e f l e c t

productivity

manner.

efficiency

answer for

Increased

to improved p r o d u c t i v i t y ,

wanting

systems

system which would is η

cycle

a valid releases

containing provide

but d i f f i c u l t

Between

Spray

(Sec.)

type

alone,

yet it

is

IMR a g e n t s .

an i n f i n i t e

target.

of

relationship

improvements however,

is

has

similar

n o t the whole

fundamental

to

Ideally,

self-releasing

numbers

On a more

in a

of

a

the

releases

(n -

practical level,

b e t w e e n 30 a n d 3 0 0 a r e a t t a i n a b l e .

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

reason ©o)

however

Self-Releasing Urethane Molding Systems

MEYER

ω >

I

I

I

η Consecutive Releases

Figure 2 . Averaged cycle time for η consecutive releases obtained as a result of eliminating the time necessary to apply external mold release spray.

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

REACTION INJECTION MOLDING

208

Productivity; system is

is

The

a function

and

primary

reason for

increased productivity. of

three

scrap rate.

reduction

In

factors:

the

terms

% Cycle

Reduction »

100

Its

cycle

of

a

self-releasing

simplest

time,

Equation

and p e r c e n t p r o d u c t i v i t y

r e d u c t i o n may b e e x p r e s s e d a s

wanting

In

5

form

machine the

i n c r e a s e as

productivity

utilization,

percent

cycle

a result

of

the

cycle

follows:

to-ta

(6)

to % Productivity

Increase

(Cycle

Basis

Only)

=

100

(to-ta)

(7)

ta Using

the

% Cycle

cycle

times

Reduction =

% Productivity To

this

trial gain

combined

of

gain,

must

and of

increased

effects

(60.5%)

is

productivity

to

a RIM

Table V .

as

Scrap,

(8

is

t a b u l a t e d In

significant.

an e f f e c t i v e

sec. 75

hr

shift)

"Table is

V"·

self-releasing

results

production The

t y p i c a l of

total

the

system can

operation.

IMR

With

(6/8

Shift)

87.5

IMR 90 Shift)

2 123,480

%

+60.5

shifts/day

different

6 d a y s / w e e k ; 45 w e e k s / y e a r

commercial

might

question

industrial

confidentiality characterization "Table

(7/8

35.0

76,950

This

in

improved

actual

22.5

M

designs?

shown

of

The

120

%

How m u c h p r o d u c t i v i t y

actual

gains

5

Increase, hr

It

process manufacturing

%

Parts/year,

*Two 8

the

scrap rate.

Features

Utilization, Parts/Hr

100,

d e t e r m i n e d by an e x t e n s i v e

Without Time,

value η -

F a s c i a P r o d u c t i v i t y w i t h and Without an IMR Agent

Productivity Cycle

the

be a d d e d

reduced

f a s c i a manufacture

realized

provide

1 for

Increas

utilization

these

Table

25% a n d ,

productivity

machine of

of

was

molds

be e x p e c t e d under

both

molds

only.

a wide

laboratory

production conditons.

the

from

range of

a n s w e r e d by e v a l u a t i n g a number

used are

A summary

To

identified tabulation

conditions,

maintain by of

tool of and

account

group these

trials

VI".

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

is

13. MEYER

Table V I . Generic

209

Self-Releasing Urethane Molding Systems

System

P r o d u c t i o n Performance

Summary

Components: Polyol-Amine M o d i f i e d + Chain

Extender

Isocyanate Molds :

F a s c i a or

Description

-

-

IMR-II

DETDA

Quasi

Prepolymer

Fascia-like

Simple

Complex

Complex

iront

Rear

Front

150

150-180

200-275

240-300

85-95

85-90

150-200

100-200

325+*

160

186+*

100

125

Mold Original

Results

Simple

Cycle,

Rear

sec. New C y c l e , No.

of

w/o

sec.

cycles

EMR

Best

case

Worst

case

50

25

25

Cycle Reduction,

%

Best

43

Worst

37

Production Increase,

%

Best

76

100

38

140

Worst

58

76

33

50

*Run s t o p p e d end p o i n t

External -

as

m o l d r e l e a s e was

little

as

once

every

25

cycle

efficiency.

ranged range Cost

was

cycles.

from 50%

a worst

to

75%

Reduction:

automatically

in

For

300 a l l ,

this

case

determined.

s t i l l

every

All

not

n e c e s s a r y , but

cycles not

of

33%

to

increases,

possible

a reasonable idea

One a p p r a o c h

unit

cost

With

reasonable assumptions part

volumes, be

Assumed

this

weight,

values

raw m a t e r i a l

140%,

the

reduced

in

cost,

a simplfied cost,

for

production increase versus

cost

The

following

is

and r e l a t e

this

sensitvity

inverse

by

on such t h i n g s

tooling study

Weight

Urethane Tooling Annual

=

=

might equating way. as

and p r o d u c t i o n reduction can

used

to

relationship:

lbs $1.00/lb

$250,000

Production

Variable Fixed

=8.90

System

Costs

Costs

=

-

200,000

= Raw M a t e r i a l (1.2)

(Initial

units costs

+

Variable

Tooling

can't

is

Basis: Part

the

should

it

cost

c a n b e made

inputs

in

answer

of

costs

with

reduction

obtained,

basic

often

once

be a f a c t o r

are

what

so

significant.

cost

question

as

improvements

figures

economic of

of

are

every

often

A l t h o u g h an exact

b o t h v a r i a b l e and f i x e d

determined.

illustrate

to

accounting

be.

molded

case

values

how m u c h ?

actual

to

a best

As

By

as

enough to

The

productivity

only

or

productivity

being t y p i c a l .

follow.

get

so,

often

series,

be g i v e n u n l e s s to

or

Costs

Costs)

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

REACTION INJECTION MOLDING

210 Cost

Equation:

Total

Cost

-

Variable

Unit

Cost

+ Fixed

Unit

(8)

Cost

Unit

Therefore: Total

Initial =

Costs

$8.90

+

200,000

=» $ 1 0 . 1 5 Employing cost

the

this value

initial of

production

"Table

VII".

VII.

$12.18

unit

percent

percent

Table

+

+

$250,000

Unit

Unit

increase

=

cost

cost

1.2

$

(8.90

+

1.25)

Units $22.33 as

a base value

reduction

for

c a n be d e t e r m i n e d .

Economic S e n s i t i v i t y Cost

Study:

of

given

manufacturing values

These

Production

of

are

shown

Increase

vs.

Reduction

Production

Raw

Tooling

Fixed

Total

Cost

Increase

Material

Amount

Cost

Cost

Reduction

(%)

$/Unit

$/Unit

$/Unit

$/Unit

(%)

0

8.90

1.25

12.18

22.33

0

25

8.90

1.00

9.74

19.64

12.0

50

8.90

.83

8.12

17.85

20.0

75

8.90

.71

6.96

16.57

25.8

100

8.90

.63

6.09

15.62

30.0

150

8.90

.50

4.87

14.27

36.1

A

separate

RIM

study

based

IMR

a n d RIM

without

benefits,

"Table

reduction

in

effects which

of

is

capital

with

VIII".

cycle

these

on

In

IMR this

investment showed

particular

yielded costs

requiremnts

similar

increased productivity

benefits

in

cost

example, a

by 63%.

saving

on

The the

comparing

savings 27% combined order

significant.

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

of

17%,

13.

Table V I I I .

C a p i t a l Investment Economic Comparison o f RIM Without IMR v s . RIM w i t h IMR

Process/Product Unit

Weight

Unit

Thickness

RIM

(#)

Raw M a t e r i a l Cycle

(In.)

($/#)

(Min.)

Parts/Hour Operating

Hours

R I M + IMfe

7.00

7.00

0.150

0.150

1.00

1.00

2.50

1.83

24.00

34.7

6,000

6,000

Clamps Capacity

Utilization

Efficiency Scrap

2

2

0.90

0.90

0.75

0.87

(%)

Actual

Production

Capital

211

Self-Releasing Urethane Molding Systems

MEYER

Equipt.

(Units)

5

2

184,680

301,380

($M)

950

% Change

-27

+63

950

Costs Raw

Material

7.00

Utilities Tooling

225

Total

225

.75

8.41

Costs*

2,000

7.97

10.82

M f g . Costs

*Estimated due

.22

1.23

Variable Fixed

7.00

.18

2,400

7.96

19.23

15.93

-17

a t $ 2 , 0 0 0 M / Y R f o r R I M a n d $ 2 , 0 0 0 + 20% f o r R I M + IMR

to Increased

labor.

Conclusions Self-releasing typically

systems

conjunction with 20%

should dealt This

and

with

this

increase,

by about a cost

IMR a g e n t s c a n

50% t o 7 5 % .

reduction

In

o f b e t w e e n 12% t o

problems

such as the need

to paint

molded p a r t s , c a n

i n a r e a l i s t i c way.

product

commercial

improving

on " e f f e c t i v e "

be e x p e c t e d .

Practical be

based

increase productivity

technology although quite

introduction,

the value

of

s t i l l

holds

t h e RIM p r o c e s s

new i n b o t h d e v e l o p m e n t

great

promise

in

radically

Itself.

Literature Cited 1. J . E. Plevyak, L. A. Sobieski, Proceedings of the ACS Division of Polymeric Materials Science and Engineering, Vol. 49, p. 619-624 (1983). 2. R. G. Dominquez, SPE NATEC '83 Conference Proceedings, p. 52. 3. J . E. Plevyak, L. A. Sobieski, Proceedings of the SPI - 6th International Technical/Marketing Conference, p. 365-369 (1983). 4. L. W. Meyer, Proceedings of the SPI - 6th International Technical/Marketing Conference, p. 372 (1983). 5. W. A. Zisman, "Adhesion and Cohesion", P. Weiss Ed. Elsevier Amsterdam, 1982.

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

REACTION INJECTION MOLDING

212

6. D. H. Bangham, R. I. Razouk, Trans. Faraday Soc V. 33, 805, (1937). 7. D. H. Kaelble, "Physical Chemistry of Adhesion"; Wiley Interscience, New York, NY (1971). 8. W. D. Harkins, "The Physical Chemistry of Surfaces", Reinhold, New York, (1952). 9. D. Tayler and J. Rutzler, "Industrial Engineering Chemistry", 50, 904 (1958). 10. G. Kraus and J . Manson, "Journal of Polymer Science", 6, 625 (1951); 8, 448 (1952). 11. G. Kraus, "Adhesion and Adhesives", John Wiley, p. 45 (1954). 12. J . McKelvey, "Polymer Processing", John Wiley, p. 161 (1962). 13. R. Taylor, Proceeding of the ACS Division of Polymeric Materials Science and Engineering Vol. 49 p. 625 (1983). RECEIVED October 5, 1984

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

14 Improved RIM Processing with Silicone Internal Mold Release Technology JOSEPH E. PLEVYAK and LORETTA A. SOBIESKI Dow Corning Corporation, Midland, MI 48640 Since its commercial introduction in 1974, reaction injection molding (RIM) of elastomeric polyurethane ha t b cost-effectiv d energy-saving proces parts with goo impac strength legislation promoting safety and damage resistance has been one key factor that helped open the American automotive market for elastomeric polyurethane fascia manufactured by the RIM process. In fact, the use of elastomeric RIM fascia is expected to reach a 50% penetration level in North America by 1985. Although the automotive market is the largest user of the RIM process, non-automotive uses of polyurethane RIM are also beginning to show much promise. From the early RIM process in 1974 to current processing techniques, chemical and mechanical improvements have been made which have decreased cycle times from five and one-half minutes in 1974 to current cycle times of two to two and one-half minutes. Although these improvements have been substantial, RIM processors s t i l l expect shorter cycle times. Presently, elastomeric polyurethane molded using the RIM process must rely on the use of external mold release agents in order to facilitate part removal from the molds. These external mold release agents must be applied before each part is made, making this application step extremely time and labor intensive. The application of external mold release agents have shown to consume 25-33 percent of the RIM cycle. An alternative to the present mold release situation, is the development of internal mold release agents which would work in conjunction with external release agents. This synergism allows the molder to produce multiple parts before the external release agent must be reapplied. 0097-6156/85/ 0270-0213$06.00/0 © 1985 American Chemical Society

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

214

REACTION INJECTION MOLDING

This paper will discuss silicone internal mold release as a major contribution towards increased RIM productivity. The value of these internal release agents together with the necessary developmental parameters of such agents will be detailed. The paper also presents details of internal mold release agents developed by Dow Corning for polyurethane RIM. Field trial results including paint aging data will be presented. Finally, an update on more-recent commercial and experimental Dow Corning internal release agents, including two stream additives will be given. This paper should enable RIM processors to see how useful internal mold release agents can be in their polyurethane RIM process and the benefits they can realize by incorporating internal release agents into their systems. Background In newly

Of

The

1974,

RIM

the

Today,

RIM

is

and

a

production, is

as

liquid

impingement closed

and

defined in

at

method

This

has

rate

over

Synonymous that

is

RIM

past

namely,

techniques,

has good

and

resistance.

Major

RIM

to

by

dispense

two a

curing

manufacturer

healthy

to

into

part

process

a

a

new

versatility. annual

classification

reaction

material,

of

excellent use

growth

elastomer

flexural RIM

molding

molded

with

of

of

injection

as

stability

current

and r e a r

maintain chief

This

largest

and

which

pressure

where

plastic

injection

in

(1).

the

dimensional

the

variety

produced

advantages

front

cycle

described

by

in

these

pressurization, external

(3)

a

—

using

RIM

strength,

excellent produced

low

chemical

polyurethane

fascia.

reaction

six

the

operations obtained

injection,

consumes

system

on

fascia

tool.

seen with

an

of

Admiral

9000

molding

current

3HP

of

(5)

part

RIM

time

cycle.

operations machine

operation

production

on

"fast-cycling

RIM"

1974

to

approximately

150

a 55

percent

in

typical

and

(6)

each

of

shown

1 these

here

were

glycol-extended with of

an

the

RIM

automotive cycle

times

equipment.

in

reduction

a

be

cylinder

Figure

Data

of

can

(2)

removal

that

equipped

is

RIM

emphasis

represented

process

movement,

application.

total

molding

molding

press

curing,

percentage the

actual

This

most

(4)

(1)

release

relative

during

injection

operations:

mold

represents

An

is

pressure

high product

Developments

The

seconds

RIM

being

The

automotive

gave

years

polyurethane.

weight

RIM

processing

with

instantly

a

RIM.

for

Reaction high

by

or

current

process

at

and

molding

tooling

several

currently

forced

molded

molding

developed

challenges.

are

was

meeting

manufacturing

low

great

process

chamber

occurs.

with

allowed the

small

relatively

solidification

molding

plastics

part

injection

thereby

performance

a

a

urethane

reaction

rates,

chemicals

mix

mold

as

plastics

rejection

design, reactive

known

leading

low

molding

is

commercial

developed process

delivery

and

Proces

first

reduced cycle seconds

overall

by

cycle

times

1981 time.

from

(1,2). Much

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

340 This

of

14.

PLEVYAK AND SOBIESKI

Silicone Internal Mold Release Technology

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

215

216

REACTION INJECTION MOLDING

the

improvement

developed

Introduction faster by

in

from of

the

reacting

faster,

thus

addition,

of

RIM

Need

75%.

Internal

much

Mold

current

react

shorter

systems

time

cure

time,

allow

steps.

and

today's

(3)

cure

expediting

faster

has

cure

and d e v e l o p green

the

on

part

ester-soap

based

each

time

strength

demolding.

closing

and

opening

is

design

and

(IMR) agents.

multiple "multiple

the

mathematical

model the

allows

basecoat

which

The

work

the an

of

external

RIM

of

are

IMR

internal

well

application. utility

cost

capacity

an

the

as

Average

observed

per

parts

alternative some of

to

Reduced

in

equipment. production

per

reduced

cycle

result

plant.

additional

systems

be

would

external

in

overall

of

be

the

by

vast

a

system

molded

before

including

mold

IMR

but

as

have been done to

and

extend

eliminate the

future

that

the

must

external

improve be

balanced of

a

part

quality. of

a

with

system

system.

econmics of

be

mold

Finally,

air

efficiency

costly the

or in

reduced.

marketable

indicate

have

labor

incorporation,

be

may

must

Too a

parts

IMR

percent

addition,

less

operating

benefits

In

be for

also

delay

of

will

an

cycle

less

point

Since

release

38

will

capacity.

times

system. fail

of

may

number

of

agent w i l l

each

means

that

applied with

improved

economic an

the

at

quality.

stripping

of

succeed

studies to

reduce

surface

mold

The

cost

technically economic

and

spraying

these

molding

mold

cost

will

time

This

current

cleaning

One

reapplication

increases

exceeds

release

that

release

times

demand

poor

as

basecoat."

during

cycle

cycle

Productivity

existing

to

be

to

economic advantages.

external

expenditure

due

referred

be

the

consumed

capital

rejected

must

generations,

significant

the

time

improvements

technology

produce

agent

to

the mold

external

to

realized

future

further

IMR

with

suggest

are

mold

to

internal

molder

release

(2)

IMR

need for of

of

frequently

twenty

cost

part.

on

the

mold

release

alternative

release

process

has

the

(1,2,4).

limits

to

fatty

being evaluated.

agent

release,

as

or

mold

conjunction

is

However,

as

mold r e l e a s e

in

using

of

An

allows

this

of

minimum

release,

reduced,

order

wax

d e p e n d i n g on

development

external

the

cycle

part.

external

industry

benefits

a

use

mold

techniques, in

external

RIM

the

synergism

reapplication.

bare metal

the

elastomeric

agents

These

of

the

molded is

from

majority

of

situation

Such

release of

molds.

application the

before

In

in

molding

release

for

addition,

Presently,

injection

mold

the

percent

of

agents

parts

reapplied.

from

The

release

release

reaction

In

improvements

cycle.

external

25-50

complexity

release

around

RIM

modifications

made

intensive.

mold

and

equipment.

externa

c a n consume

which

of

removal

agents present

using

use

part

labor

improvements

faster-moving

focused

facilitate before

and in

molded

rely

towards is

the

All

this

and

reduced polymerization

systems

interest

polyurethane,

use

extended

have

operation

must

when

amine

injection

Release

chemistry

preparation

the

for

been seen during

the

modifications

continue

faster-curing

been

cure

These

allowing

has

in

systems

equipment

Efforts

With

that

clamps.

For

and

time

fast

glycol

an a s t o u n d i n g

In

cycle

improvements

RIM the

would Several

current

favorable.

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

14.

PLEVYAK AND SOBIESKI

Requirements For it

Of An I n t e r n a l

internal

must

f u l f i l l

Rather

ability

urethane This

for is

the urethane

system's

the external

basecoat;

3)

the model c o n f i g u r a t i o n

regard

to

is

IMR

Following should fading,

parts

standard

or

rate, should

not

internal

of

given the

RIM

release

yields

better

with

a

agent

could

internal

affect can

and

more

should

In

the

of

these

another. become the

is

cleaning.

a painted

a

and

to

part

the

internal

measurement a r e molded filling

optimum

An

or

by

a of

to

a

which

physical nucleating

internal

froth

release

stability,

consideration with they

part

by comparing p h y s i c a l

that of

as

properties.

that

the finished

effects

achieved

agent.

Another is

cure

additives

t h e IMR.

provide

in physical

been

or

reactivity

through

structure

has

IMR

The the

systems

is

blowing

cell

agents

systems

complete mold

structure

the

in

should its

the use

adversely

application.

properties

release

not

of

agent.

parts

No

This

molded

significant

be o b s e r v e d . of

requirements

Materials

release might

be

ineffective

fluids

agents

can appear

which

Obviously, of

with

applications

(3).

and without

allow

Retention:

commercially

number

release

basis

green strength

on

urethane

quality,

development

paintability.

exhibit

with to

i n a change

without

differences

urethane

reactivity.

might

cost,

the performance of

of

c a n be determined

release

for

the

normal

procedures,

from the mold

reduce

systems

lower

Property mold

be tested

with

removal

elastomeric

affect

result

after

the development of

incorporating

not

of

on an equal

are paintable

microcellular

gas or

Physical of

to

A

should

these

of

surface

properties.

comparison

release.

processing in

system

Most

density

and

and r e a c t i v i t y ;

a

affect

agents

(gel) times

Nucleation: reduced

given

compare.

processing

importance i n automotive

significantly

urethane

cream

and

pain Faster

quicker part

mold

many

a

Florid

by improvements

allowing

upon

release.

to

quantify

be performed

which

in

Reactivity: obtained

to

c l e a n i n g and p a i n t i n g

aging

loss

systems

Of equal

mold

pass

provide

release

and complexity. that

which would

Paintability: to

kinetics

important

of

factors

need

property

dependent

1)

characteristics

must

impart

such a s :

2)

it

IMR

to

difficult

alternative,

requirements:

the

agent

becomes

factors,

Therefore,

the

demanding

IMR

a

requirement

of

Agent

to be a v i a b l e p r o c e s s i n g

obviously,

an

system

chemical

Release

mold r e l e a s e

a number

Release: The

217

Silicone Internal Mold Release Technology

as

which

to

for

excellent

because

the

number

meet

RIM

be i n

a l l

of of

a

molding,

w i t h one

release

additives

possible

requirements

these

one or

opposition

lack

of

increases,

requirements

becomes

limited. Organic-Silicone Current are

part

have types but

silicone

t h e good of

also

Hybrid

Technology

technology allows and part

release

properties

organic reactivity. the reactive

the synthesis

organic.

group,

of

of

Materials a silicone

The a b i l i t y

hybrid

molecules

that

c a n be designed

that

combined

to vary

a n d t h e number

with

not only

and position

various

viscosity, of

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

reactive

218

REACTION INJECTION MOLDING

groups

(i.e.,

AB,

possibility

of

Examples

these

of

ABA,

materials

structures

SILICONE—SILICONE—SILICONE

RAKE

0

0

R

R

R

G

G

G

I

of

silicone

agents

mold

will

this

silicone. the

c a n be

commercial to

the

resulting

be

to

urethane/mold

build to

in

mold

developed

the

to

a

to

protective wet-out

wet-out

once

the

act

to

the

of

is

IMR

the

the

mold

for

RIM,

urethane

inability

to

In

to

order

silicone

internal into

specified,

has

reactivity

IMR

designed

correctly

the

as

their part.

use

moiety

when

This

to

due

molded

with

functional

matrix

in

developed

concern

a

interface.

immobilized

internal

urethane

urethane

products

functionality,

urethane

the

the

differences

can

to

itself

of

the

release.

agents,

urethane/mold

rates

ability of

and

interface,

molecules

orientate

the

paintability This

silicone

will

fluids

as

urethanes

different

inability

many

fail

in

urethane/mold

at

it

The

release

into

Du

upon

paintability

rectify mold

C

facilitate

would

impart

C

decreases

Although many

Ν

the

based

surface.

surface

at

There,

which

Ν

fluids

migrate

interface. layer

formulas:

ho

molding.

selectively

following

I

tension

release

infinite

versatility.

A

RIM

phenomenon

an of

0

A

illustrates

surface

by the

ABA

C

in

shown

ORGANIC-SILICONE-ORGANIC

I

2

are

allows

dimension

AB

Ν

Figure

structures)

ORGANIC-SILICONE

A

agents

rake

and adds a unique

migrated

causes

the

matrix,

the

reacts to

IMR

the

to

thus

be

allowing

paintability. Silicone the

organic hybrids

formation

tailored

to

required

for

designed

for

structure

of

First

of

provide proper RIM the

Successful as

Q2-7119)

industry.

Field

the

faster

must

as

IMR

evaluations

demonstrated

the

release

internal an

adequately

agent of

ability

internal

mold

and

compatibility

silicone

stabilize

fluids

the

cell

IMR Q2-7119

Fluid

commercially available in

this

agent.

in are

polyurethanes.

Q2-7119 of

surfactants

surfactants

Similarly,

i n t r o d u c e d DOW CORNING an

as

These

reactivity

Silicone-Organic Hybrid

an as

also

role

(5).

of

RIM-processed

systems material

critical

stabilization.

act

as

a

foam

balance

foam

release

Dow C o r n i n g h a s known

play

polyurethane

amine and g l y c o l

functional

Table

release

(hereafter to

I

silicone

shows

agent

in

an

results amine

the

RIM

extended fluid of

to

this

extended

system. In Q2-7119

both

trials,

the

per

hundred

parts

J-car of

f a s c i a were B-side

molded using

resin

in

1-2

conjunction

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

parts

of

with

an

PLEVYAK AND SOBIESKI

Silicone Internal Mold Release Technology

MOLD EXTERNAL MOLD RELEASE BASECOAT

ΠΗΗΤΪΗΤ ^

LOW

URETHANE naioaamr

>ΡΑΙΝΤΑΒΙΏΠΥ ^ \

EXTERNAL MOLD RELEASE BASECOAT

\

MOLD KEY: Figure 2. How s i l i c o n e - o r g a n i c i n t e r n a l mold r e l e a s e agents.

hybrid

fluids

SILICONE ORGANIC function

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

REACTION INJECTION MOLDING

220

external pieces The

mold

were

release

was

terminated. on

release

agent.

molded without s t i l l

The

fascia

of

the

mold

silicone

IMR

had

no

properties

of

the

Table

I.

after RIM

Dow C o r n i n g

110-35

3-stream

at

each

stopped

the

the

cycle.

the

As

noted the

had

in

the

overall

Fluid

Extended

in

Three

System

Stream

J - c a r Rear PHR

Fascia

Q2-7119 1/16

Inch

With

With IMR

Control

Flex

(G/CC) (PSI)

Sag,

0

0.50

20+

1

20+

Table

3,000

52,400

50,300

2,400

2,500

1.20

0.89

0.48

0.40

350

240

190

200

(%)

Run N o t

E x c e l l e n t Not

Excellent

Run

Exposure

II,

depicting

system,

shows

retention

consecutive

3,600

1.01

1.04

1.00 38,900

(inch)

Year

Florida

property

0.45

1

39,000

(PSI)

Heat

Flongation

glycol

IMR

0

0.99

Moldulus

Tensile

Two

Control

Properties:

Density

6"

(PHR)

Released

Physical

table,

physical

C h e m t r e n d XMR-136

Machine

T-12

rely

Trials

5%

Parts

was

to

parts.

2.0

Additional

20

release.

trial

Q2-7119

on

after

external

time

effects

Q2-7119

Amine

Bayflex

were of

(molded without

detrimental

resulting

Admiral

trials

reapplication

excellent

control

respraying

the

The

a

to

cycles

trial

results

similar what

were

was

of

success shown w i t h

obtained

with

Q2-7119

with the

as

an

release

IMR

and

amine system.

the

IMR

before

of

parts

in

a

physical Eighteen

the

trial

was

stopped. In test

order

panels

solvent then

tests a l l

by

are that

a

the

two

the

IMR

300

exposed for

no

2

to

into agents

of

approach the be

years

between

were

metallic in

600

Primer

flake

Florida

or

Direct

and a d h e s i o n .

control

and

Q2-7119,

post-cured, and

white.

Black Results

Box of

IMR-containing

excellent.

discussed

necessitate

majority

molded w i t h

fluid

PPG D u r e t h a n e

blue

appearance

difference

trials

silicone

primed with

Durethane

evaluated for

stream

introduced

paintability

and w i t h o u t

a d h e s i o n was

the

modified

Currently, is

were

showed

Paint

In

the

toluene,

with

and then

panels. was

coated samples

South

these

check

wiped with

top

Painted 5°

to

molded with

the in

thus the

far,

urethane which

mixhead as

the

typical

successful the

molded

by

the

into

streams. either

or

RIM of RIM

i s o c y a n a t e and

separate

masterbatched

use

process Q2-7119. process

resin

sides

This

requires

both

streams.

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

14.

PLEVYAK AND SOBIESKI

Q2-7119

is

reactive

that

are

some

gellation

molded

due

times

are

which

allows

resin

the

brought

with

mixhead.

amounts

to

IMR

The

of

by

third

for

the

be

fluid streams

contains

to

aid

ratio in

green

silicone

the

in

necessary

possible

reactive

In cure

approach

three

stream polyol

may

any

An

which

or

gels.

catalyst,

reduced. in

catalyst

the

side,

filters

silicone-organic

uncatalyzed

compensate

about

is

this

approach,

with

exposed

the

catalysts

either

plugged

the

of

the

on

in

to

strength

and

placed

result

use

stream

diluted

Additional

components

reduction

green

side

If

due

of

successful

three

been

poorly

and

the at

has

control.

will

interaction

mix

which

which

to

the

isocyanate systems.

paint

the

impingement

the RIM

which

for

as

in

occur

lengthened

known

IMR,

used

can

parts

addition,

is

towards

typically

221

Silicone Internal Mold Release Technology

the

strength

internal

mold

release. Table

II.

Dow C o r n i n g

Q2-7119

Glycol

RIM

121

Admiral

Fluid

Extended

in

Three

Stream

Trials

System

Chemtrend

3-stream

Bathtub

XMR-136

Type

Mold

Machine 2.0

PHR

Q2-7119 With

Control Additional

T-12

Dabco

33

LV

Parts

Released

Physical

Sag

being

two-stream

inherently has

been

is

fast

IMR

approaches have highly

introduced reacting,

showed

Hybrid

considered

Several

currently

to

4,300

4,200

0.08

0.08

135

123

been

RIM

do

stream RIM

not

into the

the

by

Texaco

resin

absence

paintability

of and

approach. retention unique IMR

side

require

tin

systems

compounds.

III

physical which

has

shows not

tin

observed excellent

with

this

catalyzed

for

RIM,

currently

systems

are

systems

are

catalyst.

release

silicone

Multiple

been the

properties

are

The

are

Q2-7119

capability

to

One such system i s b e i n g

system and does not

processing

Table of

the

These tin

internal

C h e m i c a l Company. of

agent

and

urethane

molders.

excellent

IMR

identified

reactive

to

and

provide

Agents

a three

those systems as a two-stream r e l e a s e a g e n t . introduced

1.04 110,200

(%)

Q2-7119

pursued.

being

18

101,650

(inch)

Silicone-Organic

Although several

(PSI)

(PSI)

Heat

In

0.2

1.00

(G/CC)

Elongation

Advances

0.2

0 1

Modulus

Tensile 4"

0

Properties:

Density Flex

(PHR)

(PHR)

IMR

fluid

adversely release with Texaco

can u t i l i z e

blended due

with

this

release

is

react

to

good

two-stream results

system. Q2-7119

agent.

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

and Other as

an

REACTION INJECTION MOLDING

222

Table

III.

Dow C o r n i n g Q 2 - 7 1 1 9 Jeffamine

Fluid

in

Two

Stream

Control

IMR

Concentration

Parts

Flex

(G/CC)

Tear

(PSI)

Sag

show

demonstrated

with

expressed

a

desire

two-stream

approach

addition found

which

unlike

the

the

of

Again,

IMR

will

resulting

trial

rigorous,

the

IMR

Table

V

fluid

in

way

towards

A

by

fluid

a

had

incompatibility

desired

cure.

This

release

release

Several

and

experimental

release,

paintability, as

two

stream

trial

using

resin

RIM

addition,

fluids in

a of

property

with

adhesion

illustrates

this

the

excellent

results

paint

results

gly col-extended

physical

were

good a t

the

initial

showed

similarly

is

internal

releases

s t i l l

note

Dow

seen,

additional

The

Forty

R e l e a s e was of

no

parts.

side.

Also In

discussed,

good

a

As

RIM

and

of

an

system.

retention

were

experimental

fluid,

have been o b t a i n e d .

spread r e a l i t y

primarily

the

of

been

industry

agent.

side.

retention

stopped.

levels

versatile

Β

balance

previously

and

requirements

auto

gain

experimental

produce

release

mold

to

the

that

agents.

many

urethane

the

systems.

are

hybrid

injection

near in

future

cycle

apparent the

of

the

time

and

through

the

requirements

are

products

Research

commercializing

reaction

very

Although

silicone/organic in

in

reduction

productivity release

successfully for

an

similar

the

agents

was

stream

increase

A or

for

machines has

an amine extended system.

properties.

good.

all

release

in

terminated.

be a wide

internal

to

the

property

trials to

due

the

proper

from

directly

releases

industry,

into

the

release

molder

urethane

agent

silicone

two

RIM

RIM

success

approach,

the

to

was

be

present

two-stream

the

used

With

twenty-five

of

be

excellent

observed.

IMR

physical

to

IMR

promise

results

the

the

developed.

stream to

of

obtain

shown

added

experimental

use

impair

experimental

retention

370

to

physical

trial

retention

RIM

not

shows

before

have

order

three

was

obtained

230

410

Although

the

agent

and

needed

release time

IV

IMR

would

experimental

catalyst

0.40

240

18%

a

allow

in

have been

Table Corning

obtain

have

processability candidates

to the

yet

only

three-stream

would

of

which

paintability,

new

that

capability.

the

reactivity

fluids

3,500

0.60

(%)

(4)

1.00

3,400

(inch)

multiple-stream

be

1.0 120+

35,000

(PLI)

Estimates

to

0

32,000

(PSI)

Heat

Elongation

and

IMR

20

1.00

Modulus

Tensile

simple

With

Properties:

Density

have

Part)

Released

Physical

6"

(%

Texaco

System

can

efforts

silicone

are

satisfy well

internal

molding.

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

on

mold

14.

PLEVYAK AND SOBIESKI Table IV.

Dow

Dow C o r n i n g E x p e r i m e n t a l F l u i d s i n Two Stream Amine Extended T r i a l s

Amine

Admiral

System

9000

C h e m t r e n d XMR-136

3HP

f

80

Mustang

Front

Control

IMR

Concentration

Parts

223

Silicone Internal Mold Release Technology

(%

Part)

Released

Fascia With

IMR

0

3.1

2

40+

Physical Properties: Density Flex

Tensile 4"

(G/CC)

Modulus

Heat

(PSI) Sag.

Elongation

Table

(PSI)

V.

Dow C o r n i n g

9000

3,900

3,700

(%)

Carbide

Admiral

1.02 34,000

(inch

Glycol Union

0.99 36,000

Glycol

Experimental

Fluids

in

C h e m t r e n d XMR- 1 3 6

System

3HP

!

80

Mustang Control

IMR

Concentration

Parts

(%

Released

Two S t r e a m

Extended T r i a l s

Part)

Front

Fascia

With

0

4.0

4

25+

IMR

Physical Properties: Density Flex

Tensile 4"

(G/CC)

Modulus

Heat

(PSI)

(PSI) Sag

Elongation

(inch) (%)

0.90

0.95

39,000

31,500

3,500

3,100

0.60

0.40

150

190

Literature Cited 1. Von Hassell, A. "RIM Machinery and Materials Evolve Towards Higher Productivity," Plastics Technology, November, 1981, pg. 69. 2. Cekoric M.E., Taylor R.P. and Barrickman C.E., "Internal Mold Release The Next Step Forward in RIM Productivity," Paper 830488, SAE Automotive Engineering Congress and Exposition, Detroit, MI, February 28 - March 4, 1983.

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

224

REACTION INJECTION MOLDING

3. Ludwico W.A. and Taylor R.P., "The Bayflex 110 Series - The New Generation of RIM Materials," Paper 770836, SAE Automotive Engineering Congress and Exposition, Detroit, MI, September 26-29, 1977. 4. Von Hassel Α., "RIM Materials Take Quantum Leap Forward," Plastic Technology, March, 1983, pg 37. 5. Kendrick T.C., Kingston B.M., Lloyd N.C., and Owen M.J., "Surface Chemistry of Polyurethane Foam Formulation, Part I", Journal of Colloid and Interface Science, Volume 24, pg. 135, 1967. RECEIVED April 16, 1984

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

15 Fiberglass Reinforcements in RIM Urethanes MIKHAIL M. GIRGIS PPG Industries, Inc., Fiber Glass Research Center, Pittsburgh, PA 15230-2844 Applications for high modulus Reaction Injection Molding Urethane parts require the addition of short glass fibers to increase stiffness and dimensional stability and to reduce heat sag during painting cycle. Fiber glass reinforcement however reduc th impact resistance of thes in their composites glas forcements on RRIM urethane panel properties were investigated and compared. The fiber glass reinforcements evaluated include: milled fiber glass 1/16 in., integral chopped fiber glass strands 1/8 in., and a hybrid of milled fiber glass and chopped strand. Six major panel properties were examined for: surface quality, flex modulus, Izod impact strength, tensile strength, heat sag, and tensile elongation. Results indicate that integral chopped strand have limitations in surface quality, tensile strength, and tensile elongation, and have significant advantages over milled fiber glass in impact strength and in thermal stability (less heat sag and less anisotropy). The

current

automobile involvement production

of

such

It

a huge

machinery. However,

application

in

wider

the production

cladding

panels,

A schematic

it of

is

industry

a search of

is

clear

of

RRIM

for

to

the

weight.

geared to

a l l very

facets fast

high-speed of

t e c h n o l o g y and

has been f o c u s e d ,

at

as

the main

that

there

is

great

goods,

RRIM

polymerization

glass

in

U.S.

The

fiber

furniture,

sporting

of

manufacturing

using

diagram of

due m a i n l y

reduce auto

volume

Attention

o n RRIM u r e t h a n e s

the

RRIM to

the thinking

has l e d to

element.

in

efforts

and the upgrading

processing time,

interest

has dominated

technology. systems

strong

industry's

the nonautomotive appliance housings,

the

present

reinforcing

potential market,

for

such

as

building

and o t h e r s .

t h e RIM p r o c e s s

is

shown i n

Figure

0097-6156/85/0270-O225$06.00/0 © 1985 American Chemical Society

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

1.

226

REACTION INJECTION MOLDING The

or

basic

principle

prepolymers

mixture

then

passes

polymerization a

single

of

the

needed

in

occurs

that

than

the

that

Figure The

which

pumping low

indicates

U.S.

resistance

viscosity

required

continue

fuel

average

car weight.

synthetic

economy

of

components),

to

such as

soft,

parts in

4 χ

properties. of

expansion

over

However, bridging

at

high

is

large, Milled

preferred cylinders,

part

energy

as

shown

relative

The

fleet the

such

as

density.

fenders,

through

in

the

quarter

paint

bake

flex­

impact

formulation

steel

is

in

appears thermal

framework

due to

to

creep

observed after

oven.

modulus

and

30

Reinforcement

material

considered essential

for

thermal

can provide

acceptable

resin

(325°F),

in

auto

such

as

body

and

applications. and/or glass due t o are

are

glass of

the

mm ( 1 / 1 6 " ) in

length.

a sieve

than m i l l e d

filaments

the

appear­

processed through

and/or glass

Milled

size

limit

essentially glass

Although

fiber,

the

fiber

type is

of

the

fibers is

a

The most

have

a

defined

mill.

a thin

greater

impact

and s u r f a c e

a s p e c i f i c opening size.

thin,

reinforcement, ratio

fillers

upper

1/64". glass

appro­

straight

d e g r a d a t i o n of

length

in

very

the

with

and r e l a t i v e l y

milled

The

currently

displacement metering

RRIM t o d a y .

used of

with

lesser

inorganic

are

compatibility

parts,

their

other

flakes

their

equipped

by s h a t t e r i n g

an aspect

in

be u s e d

and h i g h

magnitude d i f f e r e n c e

and h i g h

material

(1)

(polyol)

distortion,

consist

made

equivalent

low

rigidity

and the

screen size

flakes

sieve have

of

determines 1.6

fragment

low

part

fibers

reinforcing

pieces

speed

car

materials

cannot, however,

and p o s s i b l y

discharge screens

glass.

flakes

low

are nonload-bearing

part

and to

to

glass

the

end

the

reduction in

doors,

Similar

(which

lines),

opening size

by

(which lids,

Its

wear-hardened c r i t i c a l

much s h o r t e r

front

American

relatively

urethane

part

screen

flakes

order

fibers

milled

least

low

estimate

mandates on

further

chemistry

temperature

machines

hammermill with

Glass

of

psi

5

reinforcement

Milled

smaller

in

considerably

a soft

lighterweight

no m o d i f i c a t i o n

therefore

rigid

flow

properties

the

is

addition,

legislative

parts

insensitive

glass

RIM

RIM

shaped

10

r e s i d e n c e time

fibers

In

and deck

resin

attached.

temperature

roughly

the

small

which provides

which have

body

the

between the is

modulus

popular

is

thermoplastic

developed

law.

because

of

ance.

the

part

sections.

Changes

minutes'

or

elastomeric urethane

body

moduli

material

solid

A recent

a RRIM p a r t

implies

hood

expansion.

priate

The

of

ha

ural

other

reactants

part

relatively

reactants. in

face

This

external

and r o o f

auto

glass

a major

a finished

the

w h i c h may r e q u i r e

attention

replacement

with

liquid

RRIM p r o c e s s

elastomer by

organic polymers

Therefore,

it

the from

industry

urethane

average

The

of

a t y p i c a l metal

a RIM

manufacturers

low

mold where produce

results

automotive

impact

which

Two

2.

using

capable

simple-

by h i g h - s p e e d i m p i n g e m e n t .

to

energy used

of

fascia

large

is

a closed

main features

requirement

panels,

RIM

step.

One

in

into

process

energy

lower

of

are mixed r a p i d l y

the

because than

rectangular-

b u b b l e and p a s s i n g

passed through flaked glass essentially

a

gives all

one.

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

of

at the

15.

GIRGIS

227

Fiberglass Reinforcements in RIM Urethanes

Polyol

Mix Head

Mold

Isocyanate

Figure

Figure

2.

1.

RIM u r e t h a n e

Energy requirements

process.

t o produce

and form

various

materials.

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

REACTION INJECTION MOLDING

228 Reinforced 25% In

loading or a

"high"

milled 10

sag

at

is

for

30

flow

leading

to

roughly

direction In is

order

calculated

to

a 2:1

ICI

(1/16")

chopped in

use

length

individual

orientation

of

the

is

(3)

in

impact

by w e i g h t

the

original

the

same l e v e l use

with

urethane of

of

using (2).

of

chopped integral

This

to

dissolve

in

the

curing,

step

illustrated

This

all

properties

that

there

lines

a l o n g the

least

a high

fiber

flow

strength, 0.02"

modulus

(the

RIM

1.5

bundles in

has

mm

high

to

dis­

dis­

levels

levels

the but

the been

of

integral at

to

paper

reports

the

mixture

of

strands

on p h y s i c a l p r o p e r t i e s

flaked by

fibers

at

glass

reinforcing

at

elements

Some

3 mm l e n g t h s dissolution

work

coated

by

warm

d e g r e e s of

strands

fila-

Therefore,

concept

developed. done

of

90%.

c o a t i n g system

1 2 0 ° F was

strands

of

varying

chopped

of

reduction

glass

explored.

p r o c e s s e s were

Figure

use

physical properties.

a proprietary

polyol

to

with

the

impact strength

value the

this

mica.

Milled

fully

chopped

by

in

of

anisotropy

significant

use

as

The

or

Izod

Izod

bundles

of

results

(_1)

glass

the

resistant

and chopping in

is

50%,

produces panels

resulting

the

reduced

flaked

reduce

not

not

molding,

One o f

composite.

by

chopped

urethane

at

when c o o l i n g .

glass

strands

reinforcement,

drying,

RIM

a

and a

and impact

of

results

during

greatly

strand

system

e v a l u a t e the

as

χ

ft-lb/in.,

have developed

This

the

matrix

in not

300

a c o a t i n g agent which

allowing

loading lowers

and v a r y i n g

order

such

of

along flow

properties

Ltd. with

such as

flaked

mentizatlon urethane

thus

warpage are

a c o a t i n g w h i c h was

polyols

Glass

coated

loading normally

urethane

done

5.0

been found

a length

RRIM p a r t s

resistance

22%

was

psi),

3

with

6

has

composites.

reinforcements

A d i s a d v a n t a g e of

The

10

specimen,

orientation

filaments.

warpage of

resultant

plate-like

a RIM

χ

a modulus

ΙΟ"" /^,

It

reinforcing

reinforcement

anisotropy

in

20 χ

a 4"

at

However

properties

the

for

with

for

polyols,

anistropic

of

150

(1/16")

reinforcement.

impact of

enhancement of

fibers

fibers

urethane

into

the

of

fiber

and P i l k l n g t o n

reinforcement.

and

to

fibers

art"

o b t a i n maximum r e i n f o r c e m e n t to

critical

system).

perse

0.2"

direction. of

glass the

(2)·

necessary

solves

(100

an Izod

of

expansion c o e f f i c i e n t along the

of

composites with

20%,

minutes

milled

"state

resin

produce

a c o n s i d e r a b l e degree

it

using

now t h e

urethane

loadings

325°F

thermal

urethane

an e l o n g a t i o n of

measured is

modulus

fiber

psi,

3

RIM more

as

which

RIM

does

Coating,

directly

in

one

3.

effects milled

of

loading level

fibers

of

and i n t e g r a l

and s u r f a c e

quality

Integral

chopped

of

reinforced

composites.

Experimental The

VR-75

used χ

in

RRIM m a c h i n e made b y A c c u r a t i o S y s t e m s ,

this

3 mm) w i t h

with

cores

70°C. The

The

resin

study,

and a chromium p o l i s h e d

an a f t e r m i x e r

for

hot

water

clamping force used

consisted

s e c t i o n was

circulation was of

also

a n d was

supplied

Inc.

(ASI)

steel

mold

(220

used.

It

was

controlled

by a s i m p l e

a polyurea dispersion

air in

was χ

293

equipped

at

60°C-

bag

press.

a blend

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

of

15.

GIRGIS

polymeric gravity

and short

of

1.02 a t

4,4-diisocyanto cific for

gravity

fiber

of

1.20 a t

glass is

The

shown

i n Figure

to

provide

excellent

The (polyol the

glass

side)

panel

for

ensure

were

good

each

Quality.

Class

the automotive part.

the

worst

slightly "Class

a high

for

the

unfilled on the

t h e VR-75

integrity

shearing

strand

designed to to

produce

strands. was c a r r i e d o u t a s

mixer

into

at least

follows:

t h e B-component

and the s l u r r y

postcured for

i n the mold;

each

of

was c h a r g e d

one hour

at

12 h o u r s

before

five

two p a n e l s

"A" surface

industry

to

2 5 0 ° F and test­

specimens p e r

( a t e m p l a t e was u s e d

first

Comparing the surface

that

the best

than

panels,

surface

was t h e i n t e g r a l worse

(after

as t h e i r

i n RRIM u r e t h a n e

examination

2:1

to

run-to-run comparison).

Surface

forcements

spe­

3 5 0 MPAs w a s u s e d

c o a t i n g had been

Lab f o r

the flow

c u t from

and D i s c u s s i o n

exterior

A n MDI

test

of

Results

by

(cp).

performe

the d i r e c t i o n

direction

a specific

diagram of

was p r e b l e n d e d

shear

i n the Instron

Specimens

of

physicals

The p a n e l s were were

of

B:A of

to mechanical

reinforcement

on a high

with

8 0 0 MPAs

Isocyanate having a

piping

chopped

ing. to

of

4.

resistance

conditioned Tests

ratio

The g l a s s

integral

evaluation of

machine.

side),

between 3 5 ° C - 5 0 ° C depending

used consisted

3 mm l e n g t h s . finely

fiber

kept

A simplified

glass

chopped

excellent

("B"

30°C and a v i s c o s i t y

were

loading.

fiber

diols

at a volumetric

The l i q u i d s

machine

The

chain

30°C and a v i s c o s i t y

biphenyl methylene type

the " A " side

system.

229

Fiberglass Reinforcements in RIM Urethanes

glass

flakes,

quality

it

of

was f o u n d

quality

chopped

painting)

considered

for an

several by

Milled

is

s t i l l

rein­

visual

was t h e g l a s s

strands. but i t

is

requirement

flakes and

fiber

is

considered a

A" surface.

Two surface

t e c h n i q u e s have quality:

attempts chopped posite

were

made

strands, density

been

surface

reported

gloss

to improve

i n the l i t e r a t u r e

and surface

the surface

quality

such as n u c l e a t i n g agents

by m i x i n g

dry a i r i n

roughness. of

to

integral

and decreasing

the polyol

judge

Several

slurry,

com­

but without

successIt

was n o t i c e d f r o m

the

following

factors

(1)

amount

glass

integral the

of

chopped

percent

the limited

have

loading i n

strand.

More work

needs

Flexural

Modulus.

measured

parallel

urethane

polymer has a value

show glass 3.5%

the results fibers, loadings

increased chopped

Figure

5 shows

1/8"

chopped

20%.

integral

Column Ε

shows

t h e i n c r e a s e was more

values

psi.

data

a t 23 ° C

Columns

results

strands. than

chopped

The n o n r e i n f o r c e d

8 . 5 % a n d 20% l o a d i n g s

C o l u m n D shows

of the

area.

modulus 50,000

that

quality:

by i n c r e a s i n g

the i n t e g r a l

this

flex

of about

obtained with

by about

strands;

of

in

length

decreased

and perpendicular to flow.

respectively. of

length

panels

on surface

and (2)

quality

t o be done

of molded

effects

the panel

Surface

loading and strand

strand.

number

significant

for

of

Β and C

milled

obtained

The f l e x

with

modulus

13.4% I n t e g r a l

240% o f

the

original

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

230

REACTION INJECTION MOLDING

F i g u r e 3 . Schematic of i n t e g r a l chopped s t r a n d s c o a t i n g and d i r e c t chopping p r o c e s s .

Figure 4 .

S i m p l i f i e d p i p i n g diagram of the VR-75 RRIM machine.

In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

GIRGIS

15.

Fiberglass Reinforcements in RIM Urethanes

231

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