Packaging Technology and Engineering: Pharmaceutical, Medical and Food Applications [1. ed.] 1119213916, 9781119213918

Table of contents :
Cover
Packaging Technology and Engineering:
Pharmaceutical, Medical and Food Applications
© 2020
Dedication
Contents
List of Figures
List of Tables
About the Author
Preface
Section I -

Scientific and Technological Background to Materials
1
Historical Perspective and Evolution
2 Chemical Engineering of Packaging Materials
3 Material Science and Chemistry
4 The Physics of Packaging Materials
5 Engineering of the Product: Design, Formation, and Machining
Section II -

Application and Processing
6
Packaging for Various Applications
7 Food, Pharmaceutical, and Medical Packaging
Section III -

Quality, Integrity, and Traceability
8
Suppliers and Manufacturers of Packaging
Section IV -

Revision and Information
Problems: Questions, Calculations, Estimates, and Dilemmas
Appendices, Glossary of Terms, and Abbreviations
Index

Citation preview

Packaging Technology and Engineering

Packaging Technology and Engineering Pharmaceutical, Medical and Food Applications

DIPAK K. SARKER University of Brighton UK

This edition first published 2020 © 2020 John Wiley & Sons Ltd All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, except as permitted by law. Advice on how to obtain permission to reuse material from this title is available at http://www.wiley.com/go/permissions. The right of Dipak K. Sarker to be identified as the author of this work has been asserted in accordance with law. Registered Offices John Wiley & Sons, Inc., 111 River Street, Hoboken, NJ 07030, USA John Wiley & Sons Ltd, The Atrium, Southern Gate, Chichester, West Sussex, PO19 8SQ, UK Editorial Office The Atrium, Southern Gate, Chichester, West Sussex, PO19 8SQ, UK For details of our global editorial offices, customer services, and more information about Wiley products visit us at www.wiley.com. Wiley also publishes its books in a variety of electronic formats and by print-on-demand. Some content that appears in standard print versions of this book may not be available in other formats. Limit of Liability/Disclaimer of Warranty In view of ongoing research, equipment modifications, changes in governmental regulations, and the constant flow of information relating to the use of experimental reagents, equipment, and devices, the reader is urged to review and evaluate the information provided in the package insert or instructions for each chemical, piece of equipment, reagent, or device for, among other things, any changes in the instructions or indication of usage and for added warnings and precautions. While the publisher and authors have used their best efforts in preparing this work, they make no representations or warranties with respect to the accuracy or completeness of the contents of this work and specifically disclaim all warranties, including without limitation any implied warranties of merchantability or fitness for a particular purpose. No warranty may be created or extended by sales representatives, written sales materials or promotional statements for this work. The fact that an organization, website, or product is referred to in this work as a citation and/or potential source of further information does not mean that the publisher and authors endorse the information or services the organization, website, or product may provide or recommendations it may make. This work is sold with the understanding that the publisher is not engaged in rendering professional services. The advice and strategies contained herein may not be suitable for your situation. You should consult with a specialist where appropriate. Further, readers should be aware that websites listed in this work may have changed or disappeared between when this work was written and when it is read. Neither the publisher nor authors shall be liable for any loss of profit or any other commercial damages, including but not limited to special, incidental, consequential, or other damages. Library of Congress Cataloging-in-Publication Data Names: Sarker, Dipak K., author. Title: Packaging technology and engineering : pharmaceutical, medical and food applications / Dipak Kumar Sarker. Description: First edition. | Hoboken, NJ : Wiley, 2020. | Includes bibliographical references and index. Identifiers: LCCN 2020009981 (print) | LCCN 2020009982 (ebook) | ISBN 9781119213918 (hardback) | ISBN 9781119213895 (adobe pdf) | ISBN 9781119213901 (epub) Subjects: MESH: Drug Packaging | Technology, Pharmaceutical | Food Packaging | Food Technology Classification: LCC RS159.5 (print) | LCC RS159.5 (ebook) | NLM QV 825 | DDC 615.1/8–dc23 LC record available at https://lccn.loc.gov/2020009981 LC ebook record available at https://lccn.loc.gov/2020009982 Cover Design: Wiley Cover Image: Courtesy of Dipak K. Sarker Set in 9.5/12.5pt STIXTwoText by SPi Global, Chennai, India Printed and bound by CPI Group (UK) Ltd, Croydon, CR0 4YY 10 9 8 7 6 5 4 3 2 1

Dedicated to my two bombastic, gorgeously inquisitive, and vociferous sons – Hugh and Noah.

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Contents List of Figures xi List of Tables xv About the Author xvii Preface xix Section I

Scientific and Technological Background to Materials

1 1.1 1.1.1 1.1.2 1.1.3 1.1.4 1.2 1.2.1 1.2.2 1.2.2.1 1.2.2.2 1.2.2.3 1.2.2.4 1.2.2.5 1.2.2.6 1.2.2.7 1.2.2.8

Historical Perspective and Evolution 3 Introduction 3 The Chronology of Packaging Development 3 The Origins of Commercial Packaging 6 Closures, Films, and Plastics 6 Major Types of Packaging 7 Survey of Packaging Use 9 Primary, Secondary, and Tertiary Packaging 13 Types of Packaging: An Overview and the Basics 14 The Meaning of Symbols on Packaging 16 Glass Packaging 17 Metal Packaging 18 Paper and Cardboard Packaging 19 Wooden Packaging 20 Plastic Packaging 20 Composite Packaging 22 Novel Materials: Bioplastics and Oxo-Degradable Polymers 22 References 24

2 2.1 2.2 2.3 2.3.1 2.3.2 2.4

Chemical Engineering of Packaging Materials 27 Introduction 27 Building Blocks, Extraction, and Raw Materials 30 Industrial Processes, Wood-Pulping, Processing, and Smelting 33 Refining Ores 33 Forming and Sheet-Making 35 Making Glass 36 References 41

1

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Contents

3 3.1 3.2 3.3 3.3.1 3.4 3.4.1 3.4.2 3.4.3 3.4.4 3.4.5 3.5 3.5.1 3.6 3.6.1 3.6.2 3.7 3.7.1 3.7.2 3.7.3 3.7.4 3.8 3.9 3.10

Material Science and Chemistry 43 Introduction 44 Glasses 44 Metallic Materials 48 Aluminium, Tinplate, Steel, and Brass 49 Polymeric Materials 56 Polyolefins, Cellulosics, and Polyisoprenes 64 Thermosets and Thermoforming Plastics 68 Laminates 74 Expanded Materials 79 Paper and Paperboard 80 Colorants, Opacifiers, and Colouring 84 Coal Tar Dyes, Lakes, and Pigments 90 Plasticisers and Other Additives 92 Anti-Oxidants and Preservatives 98 Oxidations by Numerous Processes 98 Barriers, Barrier Properties, and Product Modification 105 Resistant Coatings 105 Ageing and Degradation 109 Chemical Breach and Leaching 112 Water and Gas Penetration 114 Estimating the Shelf Life of Packaging 126 Chemical Testing 134 Contemporary Issues and Controversies with Modern Packaging Materials 138 References 151

4 4.1 4.2 4.2.1 4.2.1.1 4.2.2

The Physics of Packaging Materials 161 Introduction 161 Characterisation of Packaging Substrates 165 Surface and Structural Morphology 167 Printing 175 Wettability, Polymorphism, Crystallinity and Crystallites, Melting, and Phase Behaviour 179 Toughness, Tensile Strength, and Young’s Modulus 185 Brittleness, Hardness, and the Mohs Scale 187 Puncture Resistance and Slip 189 Test Methods 190 References 193

4.2.3 4.2.4 4.2.5 4.3

5 5.1 5.2 5.3 5.3.1

Engineering of the Product: Design, Formation, and Machining 197 Introduction 197 Fourdrinier Processing and Paper-Making 199 Sheeting, Injection Moulding, Thermoforming, Welding, Extrusion, Plasma Treatment, Annealing, and Curing 214 Bodies and Closures 221

Contents

5.3.2 5.4 5.4.1 5.4.2 5.4.3

Seals, Bungs, and the Septum 225 Classification of Moulded Packaging Forms 226 Bottles 229 Dosators 230 Pouches, Trays, Wallets, and Cartons 230 References 232

Section II Application and Processing 239 6 6.1 6.2 6.2.1 6.2.1.1 6.2.2 6.3

6.3.1 6.3.2 6.3.3 6.3.4 6.3.5 6.4 6.5 6.6 6.7

7 7.1 7.2 7.2.1 7.3 7.3.1 7.4 7.4.1

Packaging for Various Applications 241 Introduction 242 Hermetically Sealed Containers and Developments 248 The Tin-Plated Steel Can 251 Cans 254 Napoleon and Nicolas Appert: ‘The Father of Canning’ 256 Modern Sterilisation and Pasteurisation Procedures and the Effects of Chemistry, Temperature, Pressure, and Irradiation on the Product and Pack 264 Retorting and High-Pressure Steam 283 Radappertisation, Radurisation, and Radicisation 289 Ethylene Oxide 294 Hyperbaric Treatment 295 297 Sterilised Pouches and the Tetra Pak Metered Therapeutic Dose Devices 299 Heat-Sealed Goods and Modified Atmosphere 300 Childproof and Easy-Open Packaging 308 Multi-Dose Pharmaceutical Bottles 310 References 310

®

Food, Pharmaceutical, and Medical Packaging 317 Introduction 317 Food Packaging 320 Restrictions and Key Criteria Relevant to Foods and Beverages 327 Pharmaceutical Packaging 332 Restrictions and Key Criteria Relevant to Therapeutics 340 Medical Device Packaging 347 Restrictions and Key Criteria Relevant to Devices 354 References 359

Section III Quality, Integrity, and Traceability 367 8 8.1

Suppliers and Manufacturers of Packaging 369 Introduction 370

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Contents

8.2 8.3 8.4 8.4.1 8.4.2 8.4.3 8.4.4 8.4.4.1 8.5 8.6 8.7 8.7.1 8.8 8.8.1 8.8.2

Environmental Concerns and Sustainability 370 Recycling and After-Use 373 Tracing, Anti-Counterfeiting Technology, and Anti-Fraud Devices 388 Chemical Watermarks 391 Radiofrequency Identification and Tracking 393 Barcoding, Overt, and Covert Identifiers 394 History and Environmental Logging 399 Intelligent Packaging 404 Accelerated Testing 417 The Distribution Chain and Transport Logistics 431 Packaging Regulations and Guidelines 436 Labelling and Information 438 Safety, Health, and Practicality 442 New Trends and Opportunities 444 The Future 456 References 464

Section IV Revision and Information 475 Problems: Questions, Calculations, Estimates, and Dilemmas 477 Multiple Choice Questions (MCQs) 477 Short Answer Questions (SAQs); Worth 4 Marks 486 Very Short Answer Questions (VSAQs); Worth 2 Marks 487 Calculation Questions; Worth 20–30 Marks 488 Calculation Questions; Worth 5 Marks 490 Answers to Problems 490 References 497 Appendices, Glossary of Terms, and Abbreviations 499 Glossary of Terms and Acronyms 499 Periodic Table of Chemical Elements and Fundamental Chemistry 501 Chemical Symbols and Abbreviations 504 Scientific and Engineering Symbols 505 Unit Prefixes 508 Index 509

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List of Figures Figure 1.1

Packaging of the past. 5

Figure 1.2

Survey of packaging use: the needs fulfilled by packaging. 11

Figure 2.1

Packaging materials chemical engineering unit operations. (a) Organogram of unit operations involved in the life cycle of commercial packaging. (b) Raw materials. 28

Figure 2.2

Commodities and principal types of raw materials used for packaging. 31

Figure 2.3

Making metal, glass, and paper packaging raw materials, where all processes end with inspection and testing. 34

Figure 2.4

Types of glasses used in packaging applications. 37

Figure 3.1

Types of common glass bottles: clear or ‘flint’ (a, d, f), amber (b, e), and green (c) for foods and medicines. 46

Figure 3.2

(a–e) Tinplate structural profiles and chemical composition (not drawn to scale). 52

Figure 3.3

Tin cans using tin-plated steel (a) and manufactured in two ways (b). ‘Crown’ top of a beer bottle (c). Also using tin-plated steel, a key-opened spam can showing the soldering line (d). The two means, drawn and wall-ironed (DWI) and drawn and redrawn (DRD), of fabricating the can body and rib-making to plate for additional strength (e). 55

Figure 3.4

(a–c) Polymeric materials, percentage use, and applications. HDPE, high-density polyethylene; LDPE, low-density polyethylene; PET, polyethylene terephthalate; PP, polypropylene; PS, polystyrene; PVC, polyvinyl chloride. 57

Figure 3.5

(a–c) Examples of structure, composition, formation, and degradation of polymers. 59

Figure 3.6

(a–c) Polymeric materials and physicochemical properties.

Figure 3.7

Plastic packaging for general recycling (a), mixed recycling (b), and non-recycling (c) from a vertical fill, form, and seal (VFFS) machine. LLDPE, linear low-density polyethylene; PE, polyethylene; PET,

65

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List of Figures

polyethylene terephthalate; PP, polypropylene; PVC, polyvinyl chloride; PVdC, polyvinylidene chloride. 69 Figure 3.8

The cross-sectional structure of plastic laminates, bottles, and trays. PET, polyethylene terephthalate. 72

Figure 3.9

(a–c) The make-up of the major fractions of paper fibre materials. 74

Figure 3.10

Chemical composition (a) and physical properties (b) of wood pulp. 82

Figure 3.11

Colours, opacifiers, and colorants. 85

Figure 3.12

Anthrone and derivative compound colours used in packaging (subtle changes to structure and functionality yield different colours). 87

Figure 3.13

Opacification (a) and surface-reflecting (b) finishes. 89

Figure 3.14

Plasticisers, alloying agents, and intercalation agents.

Figure 3.15

Anti-oxidants and preservatives used in packaging materials. DEHP, di(2-ethylhexyl)phthalate; DEHS, di-2-ethylhexyl sebacate; EDTA, ethylene diamine tetraacetic acid; EVOH, ethylene vinyl alcohol. 95

Figure 3.16

Water and gas penetration. 117

Figure 3.17

Inducement of chemical change and leaching. (a) Inducement of chemical change and leaching. (b) Fundamental chemical and material tests used to follow product alteration. 119

Figure 3.18

The burst pressure apparatus used with foil lidding and heat or pressuresealed laminate blister packs. CFF, cold-form filling; COC, cyclic olefin copolymer; gsm, grams per metre squared; LDPE, low-density polyethylene; OPA, oriented polyamide; PCTFE, polychlorotrifluoroethylene; PE, polyethylene; PETG, glycol-modified polyethylene terephthalate; PP, polypropylene; PVC, polyvinyl chloride; PVdC, polyvinylidene chloride. 129

Figure 3.19

Contemporary issues in packaging. 139

Figure 4.1

Physics of packaging materials: key elements (a), mechanical parameters (b), and graphical comparison of indices (c). CB, cardboard; HDPE, high-density polyethylene; PC, polycarbonate; WLP, white-lined paperboard. 163

Figure 4.2

Packaging: surface and structural morphology. (a) Surface-whitened, treated cream paperboard fibres. (b) Unbleached brown paperboard fibres. (c) Oiled outer surface tin-coated steel can roughness. (d) Bleached and sized smooth white paper. 167

Figure 4.3

Surface form and texture. (a) Wetting phenomena with examples. (b) Packaging surface modification by wax coating. PE, polyethylene; PET, polyethylene terephthalate; PMMA, poly(methyl methacrylate); PP, polypropylene; SEM, scanning electron microscopy. 168

Figure 4.4

Packaging: surface pigmentation and printability. WLBPB, white-lined, bleached-pulp paperboard; WLMPB, white-lined, mechanical-pulp paperboard. 169

93

List of Figures

Figure 4.5

Packaging: high-resolution evaluation of the surface. 3D, threedimensional; AFM, atomic force microscope/microscopy. 171

Figure 4.6

Wettability, melting, polymorphism, and crystallites. OPP, oriented polypropylene; PCTFE, polychlorotrifluoroethylene. 172

Figure 4.7

Crush, piercing, and tear tests for the toughness of paper-, polymer-, metal-, and glass-based packaging. PP, polypropylene; PS, polystyrene. 187

Figure 5.1

The process of making paper pulp. 200

Figure 5.2

The modern Fourdrinier process of making paper. 202

Figure 5.3

The mechanical and physicochemical properties of paper: tensile index, tensile strength (Technical Association of the Paper and Pulp Industry [TAPPI] method T494), thickness, density, and grammage according to I’Anson et al. [15] and Nicholson and Page [16]. 204

Figure 5.4

Thermal interventions: manufacture of blister pack or ‘pop-out’ medicines. PVC, polyvinyl chloride; T m , melting point; T s , softening point (or softening temperature). 216

Figure 5.5

Corona discharge: plasma treatment, curing, and printability enhancement. 219

Figure 5.6

Bottles and jars. (a) Bodies and closures based on differing formats and materials (i–vii). (b) Casting of containers by blow moulding, injection moulding, and thermoforming of a variety of bottles. PET, polyethylene terephthalate. 222

Figure 5.7

(a–f) Pouches, trays, and wallets. MAP, modified atmosphere packaging; PET, polyethylene terephthalate. 228

Figure 6.1

Packaging for various applications. (a) Sample requirements and the demands placed on the container. (b) Pharmaceutical blister pack design, damage, and degradation (i–viii). PE, polyethylene. 247

Figure 6.2

The hermetically sealed tin can. 249

Figure 6.3

Can lacquers: an absence of lacquer on the outer surface (a), standard epoxy-phenolic lacquer for non-acidic contents (b), zinc oxide-containing epoxy-phenolic lacquer (c) for high-sulfur foods or those with acidic contents, and an epoxy-lacquered drawn and wall-ironed aluminium soft drinks can (d). 255

Figure 6.4

Nicolas Appert, the inventor of routine hermetic preservation of food in the first detailed ‘canning’ process using bottles in the Napoleonic era (1800s). He described canning in his seminal work as a means of routine preservation. 258

Figure 6.5

Metered filling operations by volume or by weight. FFS, fill, form, and seal. 263

Figure 6.6

Modern sterilisation and pasteurisation: the effect of heat treatment on the product. (a) Thermal deactivation of microbes and initiation of

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xiv

List of Figures

physicochemical change. (b) The sterilisation process and amassed lethality by calculation of the lethality of a process (F-value). (c) The processes initiated during thermal treatment. 267 Figure 6.7

Retorting and high-pressure steam treatment. The Fahrenheit scale continues to be widely used; for reference purposes Fahrenheit and Celsius can be converted as (∘ F = (∘ C × 1.8) + 32). 271

Figure 6.8

Cobalt-60 (60 Co) and gamma-irradiation facility. 293

Figure 6.9

Hyperbaric sterilisation and treatment. 296

Figure 6.10

Metered therapeutic devices: the metered dose inhaler device. 300

Figure 6.11

Childproof closures and easy-open packaging. 309

Figure 7.1

Food-specific packaging requirements. 322

Figure 7.2

Pharmaceutical product-specific packaging requirements. 333

Figure 7.3

Medical device-specific packaging requirements. 349

Figure 7.4

Prefilled insulin syringe packaging. (a) Insulin autoinjector and case. (b) Protective packaging designs for medical devices. HDPE, high-density polyethylene; MDPE, medium-density polyethylene; PE, polyethylene; PP, polypropylene; PS, polystyrene. 352

Figure 8.1

Environmental concerns and sustainability. 372

Figure 8.2

(a) Recycling and after-use with on-packaging indicators. (b) Urban litter and coastal packaging pollution. FTIR, Fourier transform infrared; HDPE, high-density polyethylene; LDPE, low-density polyethylene; MDPE, medium-density polyethylene; PET, polyethylene terephthalate; PP, polypropylene; PS, polystyrene. 375

Figure 8.3

Tracing, anti-counterfeiting, and anti-fraud devices and technology. PET, polyethylene terephthalate; RFID, radiofrequency identification. 389

Figure 8.4

Barcoding and covert identifiers. QR, quick response. 394

Figure 8.5

History and environmental logging indicators. 400

Figure 8.6

The simplified product distribution chain. 433

Figure 8.7

Labelling and information (foods). 439

Figure 8.8

Labelling and information (medicines) with Braille visual impairment identification. 440

Figure 8.9

New trends and opportunities. 445

Figure 8.10

The future and the demands of the consumer, manufacturer, and regulator. 456

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List of Tables Table 1.1

Packaging: contains, protects, preserves, transports, ‘informs’, and ‘sells’. 13

Table 1.2

Accepted international identity and recycling codes from the American Society for the Testing of Materials D7611 International Resin Identification Coding system, the recycling symbols of the American National Standards Institute, and the European Commission/Union identification of packaging materials for recycling (94/62/EC and 2008/98/EC). 15

Table 3.1

Metals and their use in packaging. 50

Table 3.2

The elemental composition (by percentage) of common metals used in packaging. 51

Table 3.3

Types of polymer packaging: polyolefins, cellulosics, and polyisoprenes. 66

Table 3.4

Polyethylene types and properties. 66

Table 3.5

Laminates for use in packaging for gas and water barrier properties, mechanical strength, lightweight characteristics, and low dimensionality. 75

Table 3.6

Coal tar dyes, lakes, and pigments.

Table 3.7

Resistant coatings to protect packaging and product. 106

Table 3.8

Packaging permeability for gases and water vapour recalculated and based in part on Farber et al. [33]. 108

Table 3.9

Physicochemical testing of packaging. 130

Table 4.1

Surface energy and wetting of packaging materials. 179

Table 4.2

Brittleness, hardness, and Mohs scale. 186

Table 4.3

Puncture and slip test methods. 191

Table 6.1

Fundamental requirements of packaging. 243

Table 6.2

Napoleon’s influence and the history time line from the early years of canning to the modern era. 259

Table 6.3

Thermal conductivity and heat transfer data for a range of packaging materials and packed commodities. 286

88

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List of Tables

® from Tetra

Table 6.4

Cartons, sterilised pouches, and the aseptic Tetra Brik Pak. 299

Table 6.5

Heat-sealed goods and modified atmosphere (MA) systems.

Table 7.1

Food packaging restrictions and key criteria. 324

Table 7.2

Common packaging starting materials. 336

Table 7.3

Webbing materials. 339

Table 7.4

Pharmaceutical packaging restrictions and key criteria. 342

Table 7.5

Medical device packaging restrictions and key criteria. 354

Table 8.1

Suppliers and manufacturers of packaging. 371

Table 8.2

Recycling and after-use. 380

Table 8.3

Chemical watermarks and event markers. 392

Table 8.4

Accelerated testing and shelf life prediction. 425

Table 8.5

Packaging regulations and guidelines, examples of guidelines, and aspects covered in the World Health Organization (WHO)-compliant countries of the world: the USA, the UK, and the European Union (EU). 426

303

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About the Author Dipak Sarker is a principal lecturer, a qualification related to expert teaching skills. He has a long history of academic instruction and scholarly activity – through teaching, study coordination, and peer-reviewed publication – that extends over the last 25 years. He gained a PhD in physics in 1995 from the University of East Anglia (UK), having worked at the Max-Planck Institute in Berlin, Germany; the Biophysics Group at the Institute of Food Research in Norwich, UK; the University of East Anglia in Norwich, UK; the Institut National de la Recherche Agronomique, Nantes, France; and the École Normale Supérieure, Paris, France. He has also taught and managed staff during his employment in industry and during his current industrial collaborative research. His areas of expertise traverse process engineering and analytical chemistry to materials sciences and the physics of simple and complex materials and industrial dispersions. He also has a wealth of experience based around pharmaceutical technology, medical devices, and the processing of foods. He has worked as a process and development scientist for some of the most significant global manufacturers of foods, medicines, and medical devices (Unilever, Hoffmann-La Roche, and GSK). He has supervised approximately 17 doctoral students and postdoctoral researchers and more than 40 masters students over the period of 25 years, with countless numbers of undergraduate research projects. He has collaborated with researchers, and supervised, taught, and trained postgraduates across Europe and Asia. He has also presented his works at a large number of international conferences (from Vietnam to the USA). He is the editor of two advanced drug delivery and nanotechnology journals and is on the editorial board of more than other 10 journals covering food science, materials, engineering, physics, nanotechnology, and drug delivery science and device technology. He has authored two complete books and three book chapters. He has always worked across disciplines and, despite working in the School of Pharmacy and Biomolecular Sciences, has research students and postdoctoral researchers traversing, for example, physics, chemistry, and engineering, including computational modelling of impacting droplets, process optimisation for commercial medicines, soft matter, complex fluid physics, delivery of drugs and anti-cancer nanoparticles, plasma physics, recycling of cotton and plastic waste materials, and cleaning technology for automobiles. He currently collaborates with academics and industrialists in the UK, India, China, France, the USA, Bulgaria, Kazakhstan, Turkey, and Italy.

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Preface During the writing of two other books covering processing standards and the colloid science involved in making medicinal products, I wanted to cover more of the technology of the process of manufacture and the materials used to contain and secure these very expensive and potentially hazardous materials – and this idea began in my mind more than 10 years ago. In addition to taking an interest in fashioning a food or pharmaceutical product through chemistry, I am also interested in the starting materials used in the design and fabrication of a product and its container. In a range of industrial activities and research programmes with companies, other than the fundamental medical science and technology where I do much of my research, I cover packaging and non-pharmaceutical or food materials and their design, potential reuse, and recycling. This book is targeted at a wide-ranging audience yet with specific interests relevant to a programme of study of routine handling, use, and testing of packaging forms or packaging materials. Most people are acquainted with packaging at some level but this book does not deal with everyday concepts; rather, it provides an insight into areas of interest where specific scientific and technological knowledge of packaging is needed for what essentially constitutes ‘consumed’ products. The book, however, is pragmatically broader in its remit than this and also details common and rarer packaging types and their properties and relevant technologies of manufacture, method of forming, and design for purpose. The three major fields covered are those of pharmaceutical, food, and medical device packaging (pack, seals, and closures) and the underlying processes used to create them. The book is simultaneously intended as a technical reference and as a study aid. To this end there are some calculations, problems, and dilemmas at the end of the book to help users in what is now a tried, tested, and popular format and a form of subject revision. This book should be useful for undergraduates and postgraduates alike in that it covers three of the top six big industries that make use of or derive products (medicines, food, medical devices, agriculture, petrochemical, electronics) and that are likely to be faced by modern science graduates with a suitable ‘flavouring’ of current research and some experimental data to cut across preliminary and advanced study. Naturally, being of interest to postgraduates means that this book will also be of interest to industry experts, although I would not profess to provide an authoritative guide to individual material or packaging forms in the mere several hundred pages provided here. The unique nature of this book lies in the simultaneous discussion of inter-related fields and of chemistry, physics, engineering, and therapeutic aspects within

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Preface

the same volume. Foods, pharmaceuticals and medical devices and the packaging that protects them account for more than half of all the packaging needs of the Western world. I use my expertise in nano-materials, physics, biomaterials, chemistry, chemical engineering, manufacturing, industrial practice, medicine, and food technology to populate this book more appropriately to the reader covered by the remit as indicated primarily in the full title. The book’s strengths lie in its accessible format and design that covers key topics that feature in so many professional and specific modular courses cover this subject theme. Unfortunately, many books only discuss small aspects of a larger picture; where they do describe the range of products they often miss out on application. My interest, along with most industrialists, is in emphasising the applicability of various aspects of packaging science and technology, yet illustrating that final use is dictated by the quality and chemical nature of the raw materials (ore, oil, minerals, and biomaterials) or starting materials (plastics, tinplate, glass, and paper) and the means of evaluating their suitability (quality indices, performance, and stability testing). I consider that a major asset of this book is its universality in such a synopsis of a broad yet specific content. The book is aimed primarily at all pharmaceutical, medical science and food technology courses at undergraduate and postgraduate level and ‘packaging industry’ professionals needing referential information and rapid exposure to ‘packaging and application’ relevant information at the graduate and postgraduate level. Special physical features include problems and solutions, numerical values, assertions and projections, illustrations, and an attempt at simplification along with a suitable degree of technical content. The idea for this book came to me some time ago during discussions with my dear long-standing friends and former colleagues – Dr James O’Reilly, Dr Ewen Brierley, Dr Martin Wickham, Dr Michel Cornec, Dr Romain Briandet, Professor Reinhard Miller, Dr David Clark, Professor Brian Robinson, Professor Peter Wilde, Yves Popineau, and Professor Daniel Bonn – during a brief period when we worked together in the UK, Germany, and France. Our discussions – both serious and jocular – prompted me to start thinking about a technical book worthy of writing that might combine chemistry, physics, and engineering with my more newly discovered and passionate area of interest of sustainability and recycling in the context of industrial processes. More than 20 years on and after writing two ‘pharmaceutical technology’ books en route, I finally got around to writing a book covering materials, processes, and design applications despite some very serious health hiccoughs along the way. The person who got me through this most difficult spell and barrage of illnesses, ultimately achieving complete recovery, was my wonderful wife, Dr Ralitza Valtcheva-Sarker. I guess part of the credit for pushing me to write this book also has to go to colleagues past and those present at my current place of employment in the School of Pharmacy and Biomolecular Sciences at the University of Brighton, UK. My colleagues shared out new lectures in medical and pharmaceutical packaging and pharmaceutical and medical device technology to me and, therefore, pushed me into an area not studied at length before. Brighton 2020

Dipak K. Sarker

1

Section I Scientific and Technological Background to Materials

3

1 Historical Perspective and Evolution CHAPTER MENU Introduction, 3 Survey of Packaging Use, 9

Abstract This chapter covers a brief chronology of the development of packaging materials and types of packaging containers through time. The chapter goes on to survey packaging use in terms of containment or collation of units. Following on from this is the fundamental classification of packaging and its role in terms of providing information. The chapter then moves on to a brief description of the various types and subtypes of packaging materials.

Keywords use; application; marketing; benefits; classification; identity; novel materials

1.1

Introduction

1.1.1

The Chronology of Packaging Development

The use of packaging is often thought of as an industrial-age concept but this is entirely untrue. In more ancient times products of economic or nutritional value were always wrapped in a suitable material to convey the need to protect the contents. The Roman emperors and Byzantine kings frequently wrapped precious goods in all manner of materials from woven rattan baskets to carved and gilded in-laid ebony boxes. Expensive luxury goods such as chalices and ceremonial goods are almost always stored in a suitable presentation case that demonstrates the value of the product contained within. Perfumes, chrism oils, and ceremonial jewellery have always been contained in sculpted and carved lidded boxes and glazed pottery. However, the use of bespoke packaging is really a modern-age phenomenon. Packaging use began with leaves and birch bark and other natural materials. In antiquity and prehistoric times humans wrapped their foods in crudely fashioned carriers and containers and also pelts and hides. The mass production of containers later involved woven materials (e.g. rushes and reeds) to create baskets Packaging Technology and Engineering: Pharmaceutical, Medical and Food Applications, First Edition. Dipak K. Sarker. © 2020 John Wiley & Sons Ltd. Published 2020 by John Wiley & Sons Ltd.

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and carriers and also textiles, pottery, and bronze amphora and carved objects (e.g. ivory, antler horn, and wood). Recent estimates place ‘crude glass’ or vitrified materials and wood packaging use to at least 3000 BCE and these artefacts come from the Indus Valley civilisations and Mesopotamia. In the modern era, that is, since the early 1900s, paper and cardboard have become extremely important packaging materials. Following the invention of plastics, the emerging industries making commercial packaging substituted plastic for paper as a primary packaging material. Many modern environmentalists hanker back to the times of the English Georgian and Victorian periods when forms of waxed paper were commonly used to wrap foods, such as cheese, butter, or meat, and pharmaceutical products, such as dried forms of poultices, pills (comprimés), and lozenges or oral dosage forms. A revolutionary step in packaging occurred in 1810 when Peter Durand, a British merchant, obtained a patent (UK no. 3372) for the first metal can. This can was for preservation packaging made from sheet metal to create a ‘cylindrical canister’. The actual invention of the ‘tin can’ is put down to Philippe de Girard of France, from whence the idea was taken up by Peter Durand. The idea of using hermetically sealed ‘canning’ containers, based on ab initio food preservation work in glass containers, had been proposed initially by the inventor Nicolas Appert in 1809. Appert’s outstanding work, looking at increasing the nutritional and microbiological safety of foods, pioneered sterilisation technology and glass bottle preservation. Durand went on in 1812 to sell his patent to two entrepreneurs, Bryan Donkin and John Hall, who refined the process and product. Donkin and Hall established the world’s first commercial canning factory in Southwark Park Road, London, UK. Unfortunately, the earliest tin cans were sealed by soldering based on a tin–lead alloy. A cumulative poisoning causing persistent ingestion did occur after a period owing to the toxic nature of the lead in the solder, which was particularly enhanced when the contents of the can were mildly acidic. As a result, a double-seamed three-piece can began to be used from 1900. In later times the lead-based solder was replaced with arc welding of the sheet ‘tinplate’. Tinplate became widely popular as it represented a stable, long-lasting, and impenetrable means of packaging for foods. The choice of packaging used conveys information as to the value of the product. For example, since approximately 2015 (and unchanged as of 2019), and depending on the source, glass is valued at US$0.1–0.6/kg (recovered glass US$0.02/kg), aluminium is valued at US$2–4/kg, tinplate is valued at US$0.7–1.1/kg, and higher grade paperboard is valued at US$0.3–0.6/kg; these contrast with most routine polyolefins (cheaper plastics, such as polypropylene [PP] and polyethylene [PE]), which are valued at US$0.1–0.5/kg. Therefore, choosing glass, which is dense (2.5–3.4 times that of paper and plastic), with a prerequisite for a greater than 0.2 cm wall thickness for strength, in the modern era suggests a high-value content since glass is both expensive and heavy and, therefore, has associated increased shipping costs. For many premium products the additional cost may be deflected by the large cost of the contents. For example, the cost of a can of green beans versus the cost of a bottle of champagne. In the former the can cost is approximately £0.02–0.05, whereas in the latter the bottle cost is approximately £0.50–1.00; this is because in the latter the contents cost at least 500 times more. A series of different types of pharmaceutical packaging from across a 100 year period are shown in Figure 1.1. Amber glassware represents about 30% of medicine bottles. Modern

1.1 Introduction

(a)

(b)

(c)

(d)

(e)

(f)

Figure 1.1

Packaging of the past.

medicine bottles are often fabricated from polyester tinted to mimic the old-style amber glass bottles. A blue-tinted bottle is shown in the insert in Figure 1.1a. Other forms of bottles, such as frosted or tinted vessels, were also used across products in the past; in modern times, these are used to aid product promotion. Figure 1.1b shows all-aluminium screw-top medicine cans that were used in the past but are used much less in the modern era. These have been superseded in many respects by the push-out or ‘blister pack’ form of medicines. Figure 1.1c shows a very old cork-topped bottle and a Victorian–Edwardian steel box for pills, which are practically never seen in the modern era, except for marketing promotions. Figure 1.1 shows a range of mid-twentieth century, Edwardian, Victorian, and earlier packaging materials used for medicines. The containers cover green chromium glass, iron oxide amber glass, flint glass, and other common forms seen more routinely today, such as paperboard cartons and aluminium closures. The ‘earthenware’ pottery vessel used in the past for medicine, milk, beer, and oil is rarely used in contemporary society but does find a place in speciality products as a marketing tool used to infer tradition and antiquity. Looking carefully at the range of packaging and comparing it with that seen customarily in pharmacies, artisanal, ‘24 hour’, and mini-mart shops and supermarkets used mostly today there is a stark contrast and difference in Figure 1.1 by virtue of the absence of plastic packaging in the period before 1950 [1].

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1.1.2 The Origins of Commercial Packaging Andreas Bernhardt began wrapping products in paper and waxed paper for water retention stamped with his name and identification in Germany in 1551. Packaging uses and requirements have changed a lot in the modern era and most spectacularly over the last 150 or so years of purpose-crafted commercial containment. The diversity of past packaging can be seen in Figure 1.1, with examples of flint, amber, green, and blue glass pharmaceutical sample bottles and a range of aluminium cans, paper, card, and pottery primary and secondary packaging. Some of the samples in Figure 1.1 date from the 1960s and 1970s but others date back to the Victorian and Edwardian periods (1870s–1900s). The sometimes perceived as ‘modern-era’ plastics industry actually started with John Wesley Hyatt, who invented modified cellulose in 1869, and, Leo Hendrik Baekeland, who invented resinous early plastic in 1907 in the USA. Other product examples include the ubiquitous tobacco snuff box (Mander Brothers) of the 1800s, the Beechams pills carton (UK) of the Victorian era in the 1840s, and the Lyons loose tea can (Ireland) and Laymon’s aspirin tin (USA) of the Edwardian era in the 1900s. The more familiar forms of plastic containment that first appeared in the 1950s–1970s include the detergent and – the now infamous – mass-produced carbonated drinks polyethylene terephthalate (PET) bottle. The tin can means of excluding air, light, and water for tea leaves is still used by many companies such as Jin Jun Mei (China), Whittard (UK), Tafelgut (Germany), and Twinings (UK), as part of a value-adding marketing tool and for protection of delicate flavours and volatile oils. The sea-change position of the use of tin-plated steel (tinplate) and the tin can as a standard form of packaging will be discussed in Chapter 3.

1.1.3 Closures, Films, and Plastics Rubber used in sealings and liddings became a mainstay of commercial packaging when, in 1849, Charles Goodyear and Thomas Hancock developed a method that destroyed the ‘tacky–sticky’ property of the material and added extra elasticity to natural rubber. In 1851 hard rubber, often referred to as ebonite, became commercially available in the Western world. A completely new revolutionary form of packaging was created in the invention of plastic. The innovative original artificial plastic was created by Alexander Parker in 1838 and was displayed at the Grand International Fair in London in 1862. This ‘parkesin’ rigid ‘resin’ was thought to be able to replace natural materials such as hardwoods and ivory. In 1892 William Painter patented the still ubiquitously used ‘crown cap’ closure (see Figure 3.3c) for bottles shaped from glass [1], which kept air (containing degrading oxygen) out and product flavours locked in. Also, in 1870 Hyatt took out a patent for ‘celluloid’ produced from cellulose in highly controlled conditions, under high pressure and temperatures. This created a polymer with low nitrate content for many different types of product wrappings. This discovery is now thought of as the first commercialised plastic and remained the only ‘plastic’ until 1907, when Baekeland produced ‘Bakelite’ (also spelt as Baekelite). Bakelite was universally used until the 1970s but was replaced by a new wave of plastics. A more exact understanding of plastics arose in 1920, when Hermann Staudinger’s revolutionary idea was extolled and the notion of a plastic as a physical property rather than a chemical class came into fruition. All plastics, rubber, and cellulose are polymers or macromolecules

1.1 Introduction

but notably some do not show significant plasticity or deformability without brittle rupture. Staudinger’s pioneering work concerning ‘polymer science’ was awarded the Nobel Prize in 1953.

1.1.4

Major Types of Packaging

Plastic packaging had begun to be used widely across the globe after the 1950s and this has led to the present ‘mountains’ of undegraded waste that are still added to. Polyvinylidene chloride, or Saran , was first used as a moisture barrier in 1946. In 1960 the two-piece drawn and wall-ironed (DWI) can was developed and in 1967 the ring-pull opening was invented. Towards the end of the 1970s the plastic packaging sector had begun to grow, with the blow-moulded PET bottle invented by DuPont. It was not until after the Second World War that general use of plastics in packaging applications started at a significant level. PE was mass produced during this period in Europe and became an easily obtained material from the late 1940s. At the beginning of this period it was a substitute for the wax paper used in bread packaging and still observed until the 1980s. The growth in plastic packaging use has accelerated at an astonishing pace since the 1970s. The technology available today and the requirements for a non-perishable nature mean that many previously used materials (e.g. waxed paper) have been replaced by more suitable and economically viable materials such as glass, metal, plastic, paper, and cardboard. Before the 1950s packaging was essentially only used to protect the product during transport and storage. However, with the plethora of newer materials it has also begun to be used to advertise the product with the form, colour, printing, including fonts, and logos being a major part of the marketing process. This is simply because form-differentiated packaging creates a distinction between the same types of products placed side by side on outlet shelves. The modern practice of favouring plastic as the packaging material of choice is, however, not without significant environmental concerns, with some amount greater than 15 million tonnes being present in the seas in 2017 and possibly as much as 30 million tonnes in 2019 according to recent estimates. The USA and Western European countries in 2000 consumed about 24% each of the world’s plastics. Plastics such as PP are thought (based on chemical modelling and accelerated ageing study tests) to be able to persist in landfill for approximately 500 years. Single-use plastics, which are discarded after one use (incinerated or sent for landfill), accounted for approximately 50% of all plastic packaging in 2019. Glass-based packaging is a form of packaging that has stood the test of time. This type of packaging first began to be used around 1500 BCE by artisans in Egypt. Glass, an amorphous silicate matrix, was first used in the form of a pot or vessel. Its fabrication starts when limestone, soda, sand, and silicates are co-melted and shaped during the fluid phase at a temperature of many hundreds of degrees Celsius and allowed to cool into glass packaging. From about 1200 BCE, pots and containers started to be made from moulded glass on a semi-commercial basis. Completely transparent glass was invented in the centuries following the development of reproducible blowing and with the aid of a ‘drawing pipe’ by the Phoenicians in 300 BCE. During the two millennia that followed, the development of clear (flint) glass, via augmented glass production techniques, has been incrementally improved and expanded to all manner of products. To date, the development of the automated rotary glass-manufacturing machine in 1889 affected industrial-scale glass manufacturing and,

®

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therefore, packaging the most of any of these innovations. Surprisingly, given its cost, after the 1970s glass packaging began to be used ubiquitously for the protection of high- and low-value products and to aid the visibility of pack contents. It continues to demonstrate a wide variety of uses today and remains a form of packaging that can be recycled; in the modern era this is an important consideration. Metal packaging, used in antiquity in the form of gold, silver, and pewter boxes as well as strong alloys such as bronze and brass for coverings and to protect many products, is finding new uses in modern packaging technology. Tin – an essential part of tin-plated steel, the basis of almost all food cans – became a viable surface treatment following the production of tin in sheet form in Bohemia from 1200. Later, at the beginning of the 1300s, metal cans were first used to store food. These cans were different from those of the modern era but remained an unwritten ‘secret’ until the 1600s. William Underwood aided in the further development of the food can by the development of an improved process for fabricating steel plate. The notions of food cans and of canning were pushed to the forefront of public awareness in 1809 when Napoleon Bonaparte offered a reward of 12 000 French Francs (∼£1000), a huge prize in that period, to any inventor who could develop a method to protect army food supplies during envisioned military excursions and campaigns. The opportunity was seized by Nicolas Appert, a confectioner from Paris (portrayed in Figure 6.4), who presented a selection of pasteurised lidded glass jars, following on from initial investigations. He found that a steel can covered with a fine layer of tin was able to preserve food post heating in an aseptic process and without the can container rusting in the damp. A year later Englishman Peter Durand patented the familiar-shaped cylindrical can with his coated tinplate as an invention. This development spawned a host of subsequent modifications and adaptations. The first printed box was made in the USA in 1866 but went on to be used for containment of many types of product. Fast-forwarding to 1910, the tin box was found in commercial environments ubiquitously until the point when aluminium in a suitable form became available. The aluminium foil box was developed in the early part of 1950, and in 1959 the first aluminium can-based food became available. In the nineteenth century sharp objects combined with hammers were used to open metal packaging and tin cans, which was a highly unsatisfactory state of affairs. Later on and at least until the middle of the twentieth century, the ‘pig-stick’ tin can opener – a brutal spear-looking object, based on a steel spike and sliding blade – was used to open food products. The routine use of the pig-stick device and the sharp serrated edge it created resulted in many hand injuries. The pivoting can opener was developed by E.J. Warner in 1858, followed by the ‘church key’ of 1892. The pivoting can opener was improved on in 1925 by the Star Can Opener Company, and yet further improved in the now familiar pliers-form Bunker-type modern can opener first developed in 1931 by the Bunker Clancy Company. Electric can openers were developed in the late 1950s and the side can opener was developed in the 1980s. Packaging with tear-open lids was first developed in 1966 and has become increasingly evident in use over the last five decades. Paper, which is still used universally in the present times, is the oldest conveniently reshaped packaging material available. In ancient Egypt in 5000 BCE, papyrus – a material based on marsh reeds – was used to wrap foods and hold objects together. Many millennia later in China, mulberry tree bark, reconstituted as paper, was used in the first and second centuries BCE to pack food. Paper-making methodologies and techniques improved during

1.2 Survey of Packaging Use

the subsequent 15 centuries. These high-quality papers and products and technological know-how were then transferred to the Middle East. From there paper-making techniques reached Europe, and then from Western Europe they reached England in 1310 and subsequently America in 1609. In 1817 the first commercial cardboard box was produced in England, almost 200 years after being made in a basic and simplistic form in China. The corrugated form of cardboard was invented in the 1850s, gradually replacing wooden boxes in the trade and transportation of goods such as fruit to the point at which, today wooden boxes are barely seen for food products. Selected examples of continuing wooden box or crate use do persist but these are relatively rare. The twentieth century has been the most prominent period for universal paper and cardboard use with the added advantage of recyclability and biodegradability. This is an important consideration since, in the UK in 2013 alone, approximately 750 000 tonnes of household waste, rich in plastic and paperboard materials, went for landfill disposal.

1.2

Survey of Packaging Use

Consumers demand convenience from their packaging, so packages can have features that add convenience in distribution, handling, stacking, display, sale, opening, reclosing, use, and reuse. Packaging materials are used for a host of commercial product-containment purposes. These traverse informatics and IT, such as CD or USB stick packaging, through to the diverse range of degradable (e.g. cooked meat) and non-degradable (e.g. retorted canned fish) foods and also the protective and containing roles of packaging used for over-the-counter and prescription-only medicines, surgical aids, or emergency medicines, and to safeguard the consumer against accidental consumption or contamination. Everything from furniture to garden centre compost and on to mobile phone devices is enveloped in an informative and protective sheath of packaging. In this book, topics centre on foods, medicines, and medical devices but these still account for only approximately 45–50% of global packaging use. Packaging accounts for about one-third of the use of all polymeric materials and is by far the single biggest use of the materials. Medicine bottles and closures alone, for example, account for about one-third of pharmaceutical packaging use. A definition of the meaning of packaging indicates that packaging fulfils at least five roles. The first of these is the socioeconomic role of packaging; since the packaging has a value of its own this is not simply attributable to the contents being of significant value. Consequently, a good definition suggests that packaging is a precious material that protects the product within, allows the product to reach the customer in the most hygienic and safest form, and makes it easier to transport and store the product after delivery. The socioeconomic influences on packaging form are technological, political, sociocultural, availability (being at hand), ecological, economic, and demographic. Packaging has often been referred to as originating as a consequence of these socioeconomic influences, as the ‘silent salesman’, and both has managed to enter the commercial sphere and is used as a vehicle in the marketing arena in the form of the ‘8P’s’ or ‘holy octet’ concept. The holy octet involves the product itself as well as aspects of pricing, placement, promotion, participant involvement, physical form, process of use, and finally a notion of personal targeting, all obtained from the idea of a malleable marketing mix to appeal to the customer [2]. The other four criteria

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that define packaging cover the basic functions of any packaging, which can be effectively summarised as relating to the provision of a description (information, salesmanship, and promotion) of the product, very important containment, equally important protection for storage capability, and the ability to be successfully transported or shipped across the globe. The reasons for adherence to packaging use are manifold but are based on the ability of the materials to reduce wastage and, in doing so, because of scarcity or perishable status, reduce the product cost. A crude estimate suggests that 30–50% of ‘thrown food’ and medicinal products are disposed of because of inadequate storage; therefore, extending shelf life by a means that requires passive storage without energy consumption consequently saves energy (need for freezing/refrigeration/cooling). The pack itself also has a very important mechanical role in that it reduces damage while presenting the product in an aesthetically pleasing form. For a number of products that require a guarantee of microbial security, the pack also serves as a means to avoid pack tampering (see Chapter 8). At the same time the pack must provide information (safety, nutrition, dosage strength, mode of operation) to the customer and, therefore, aid selection or choice-making. When well designed, a package can provide convenience, as in the case of ring-pull or easy-opening closures, and may in the presentation of an easily recognisable form aid the marketing of goods. However, the complexity and sheer number of layers of packaging in composite materials combined with the non-biodegradable nature of some forms of packaging (plastic, laminated paper, glass) have contributed enormously to concerns raised over packaging persistence in the environment, unsightly littering, and global pollution. These then lead to angst over after-use, disposal in terms of the cost, and the extent of ‘effective’ disposal or energy recovery. These more negative aspects have led to a perception of overpackaging among the general public for products such as oven-ready foods and pharmaceutical packages. An often misunderstood but very obvious purpose of packaging is its use in marketing and recognition, through which, by application of careful tactical and market opportunity surveillance, a specific design that means market-leading capability can be crafted. Branding and brand identity have very powerful roles in marketing of the product (food, medicine, device) and an assurance to engage the customer. Where this is not done successfully, the best an organisation can hope for is simply market-leader following. Consequently, all successful design considerations take into account product uniqueness, distinctiveness, and functionality; without the last a customer purchases the product only once and is discouraged by the awkwardness of the product. For pharmaceuticals and medical devices packaging is a fundamental and key part of current good manufacturing practice (cGMP) and also part of good distribution practice (GDP); cGMP and GDP are enshrined in the international standard British Standard (BS)-European Norm (EN)-International Organization for Standardization (ISO) 9001:2008 and are intimately associated with the assurance of quality and, by implication, safety. The stringent label requirements of packaging serve to ‘protect and inform’ the recipient with the provision of important information, such as dosing and dosage strength, adverse effects, and allergenicity, reinforced by the legal aspects of commercial activity. The form of the pack and its performance, such as ease of bottle opening or ease of dispensing of a tablet from a push-out pack or blister pack, need to be consistent with mass manufacture and distribution, but this is not achieved without appropriate production testing and the associated higher cost of producing consistently high quality.

1.2 Survey of Packaging Use

Role of packaging

Technological

Social and cultural

Legal and political

Economic

Easily sourced

Demographic

Environmental

Figure 1.2

Survey of packaging use: the needs fulfilled by packaging.

Figure 1.2 shows that the role of packaging is associated with a cluster of needs. The packaging needs include technological requirements that fit societal or speciality requirements, such as multiple opening and resealing. Legal requirements and political compliance include wastage and recycling guidelines; social and cultural requirements are also important, often mapping to creeds and cultures such as halal or kosher foods (and the guarantee of freedom from animal-derived materials, e.g. gelatin or dairy produce). Further needs for most packaging also involve cost minimisation, which is linked to financial accessibility and economic drivers [3], and ubiquitously sourced materials with no restrictions on availability. Demographic requirements, which might include easy access or restriction-to-access packaging for the elderly and infants, often define the needs for some high-risk products. Finally, and of increasingly important decision-informing status, concerns about environmental impact, issues covering material sustainability, and efforts to recycle and reuse without impact on the anthrosphere, geosphere, or biosphere have a powerful role in product engineering and composition. All these needs amalgamate to dictate the overall requirements placed on packaging materials and their routine use in the commercial sector. Central to the use of various types of packaging are the pivotal notions of their role (primary, secondary, and tertiary) and what type of environment might be appropriate for the packaging (Figure 1.2). For example, plastic may be the best first choice but then, given the informing nature of the container, use of printed paperboard may present the best financial choice. The selection of packaging use is modelled against maintenance of standards, conveyance of identity, mechanical strength, product quality (both required and obtainable), and the purity required of the contained goods (particularly true of medicines). A good pack, therefore, needs to provide full information, be familiar or instantly recognisable, be

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based on a design for frequent or intermittent use (as required), and demonstrate suitability for its intended use. Additionally, where portioning of the product is required, such as multi-vitamins, infant formula, dietary or meal replacements, or traditional pharmaceuticals, careful control of doses leads to medical and therapeutic compliance. Marketing and identity, aligned with matching product trends in pack volume, size, and form, are often indicators of product success. Because of the nature of the commercial sector packages need to be able to conform to high-output manufacturing but also need some thought embedded in the design as a ‘superior’ quality product can have an associated cost. Reliable packaging universally prevents water and humidity breach and demonstrates mechanical resistance (shock, strength), chemical resistance (absorption; corrosion; air and gas exclusion; chemical, sterilant, or pH resistivity), microbial resistance, ease of handling, ease of repeated processing, and light exclusion. Regulation adherence of the materials used and framed pragmatically within the commercial goals of high-numbered product sales must consider materials, product manufacture, and logistical cost – this usually means the pack should be lightweight, easily packed, and yet physically robust. The unit cost of the product given its manufacturing and shipping costs gives rise to the idea of lean manufacturing and cost trimming, some of which might arise from contact with a regular supplier and specific business approaches, such as just-in-time manufacturing. In order to satisfy the requirements of intimate contact with the contents, all packaging should ideally be chemically inert, unreactive, non-additive, non-absorptive, and, therefore, does not add to or corrupt the pack contents. Additionally, the package is required by the manufacturer and customer alike to offer protection against deterioration and contamination during handling and transport. Storage and transport conditions are likely to vary considerably and will include alterations in freezer conditions, cold-room conditions, and ambient or room temperature handling. Strict control of the physical and spatial separation of packs is needed during storage as this may encourage temperature and pressure gradients in the pack, possibly leading to weaknesses, pinholes, tears, and cracks. A regular part of the development of commercial products will, therefore, consist of inspections, history-marking steps, label scrutiny, sampling procedures, establishment of non-conformance or rejection criteria, record-keeping for shipments, and product security during transportation and the distribution chain. As a ‘protector’ of the product within, the packaging has a key role in resisting physical impacts, such as is seen with perishables in the squashing, wetting, and bruising of shipped fruit. Packaging, therefore, allows for the product to reach the consumer in the most economical and ideal way possible despite the transit time and variable conditions experienced during shipment and storage. As a result of modern societal changes, including changes in family dynamics and time spent in traditional activities, such as cooking, there have been a number of changes required for commercial products, such as foods. Highly packaged goods are often preferred in modern times because people have less time to pursue ‘traditional’ preparatory activities in the household and there is a higher need for convenience but with the guarantee of safety and hygiene. Consequently, packaging consumption is higher in developed than in developing countries, the latter of which in turn consume more packaging than underdeveloped countries. This must be balanced against sociopolitical notions, such as global warming (from incineration and refining), recycling, and environmental pollution, which are more evident and higher on the political agenda in the developed world.

1.2 Survey of Packaging Use

1.2.1

Primary, Secondary, and Tertiary Packaging

Packaging type is classified into three rather subjective categories based entirely on their areas of use. Primary packaging (cf. sales packaging) is defined as the packaging that surrounds the product when sold to and received by the final consumer. In essence, it includes the packaging material substance or product that is in direct contact with the fill product and the other packaging components (i.e. lid, instructions). Secondary packaging, also referred to as group or grouping packaging, is packaging used to collate or hold together the primary packaging or units being sold and is used for ease of transportation. In modern times of global trade this can involve shipments back and forth across the globe. This process is undertaken by collecting the products together (e.g. a paperboard box holding blister trays of pharmaceutical pills or a corrugated cardboard box holding plastic laminated cartons of milk). Tertiary packaging is occasionally referred to as transport packaging and is needed to make convenient bundles of secondary packaged goods for mass transport or ultimate delivery of units or secondary packaging; it is used specifically to prevent physical damage that may occur during delivery (e.g. high-density polyethylene [HDPE] skip or pallet). Recent studies based on damage to all transported foods, estimated at approximately 5–10% of all foods transported, demonstrate the value of primary and secondary packaging [4]. The term ‘unit load’ is often used to represent the packaging group consisting of the compounding together of more than one type of packaging for delivery processes and can be exemplified as the unit repackaged with stretch film on the palette. Consumer packaging is a term used to describe the packaging of a unit that reaches the final consumer from a retail outlet and this represents the received goods that make an impression on the consumer. Identification of materials, such as plastics, that can be reutilised is an important part of the push for improved recycling. The three types of basic packaging – primary, secondary, and tertiary – encompass virtually all forms of containment (Table 1.1), which often however possess different degrees of reusability. Primary packaging has a role in containing and protecting the commodity directly and is generally based on high-purity materials; Table 1.1

Packaging: contains, protects, preserves, transports, ‘informs’, and ‘sells’.

Types of use/function

Risk

Example

Primary: protects and directly envelops the drug (pharmacy shelf or home)

Could compromise and contaminate the product

Can, pouch, blister, jar, bottle, or ampoule

Secondary: protects the packaging that protects the drug (for warehousing); used to group primary packages together

Misleading information on the pack

Carton or box

Tertiary: protects the secondary packaging. Purpose: bulk handling, warehouse storage, and transport shipping. The most common form is a palletised unit load that packs tightly into shipping/haulage containers

Pallet, hopper, skip, or over-wrap

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secondary packaging protects the integrity of the primary; and tertiary protects the secondary packaging and permits shipping and transportation of the primary and secondary products within the tertiary packaging. Consequently, secondary and tertiary packaging need lower levels of material purity and, therefore, may be more open to incorporation of recycled material. Occasionally, primary and secondary packaging are combined but they may also not have the same physical presence, for example shrink-wrap (secondary) covering of a carton (primary); this is often used when the product cannot be easily corrupted by the carton. Primary packaging may be something like a sachet, a bottle, or a blister, which are often not accessible to current recycling practices. Secondary packaging is typified by a carton or a box and tertiary packaging is typified by a carton with an outer wrap. Tertiary packaging is typically a skip, drum, crate, etc. and represents containers that can make use of mixed aggregated recycled materials. The risk of primary packaging lies in its intimate contact with the product, which could be seen as a risk of product compromise and contamination. Typically this could involve the increasing loading of plasticiser or toxic materials in product contact packaging resulting from recycling. Chemical risk is less important in secondary packaging but significant risk arises from misleading information on the pack that could potentially cause injury to the recipient. The international identity code (Table 1.2) ascribed to the recycling of materials used was devised in combination by the bodies concerned with packaging use but fell under the remit of the American Society for the Testing of Materials (ASTM), which encompasses the International Resin Identification Code (RIC); the American National Standards Institute; and the European Commission (based on decision 97/127/EC – ID System for Packaging Materials, which is underpinned by council directive 94/62/EC). These bodies and nomenclature systems together have helped group materials into six usable categories (Table 1.2). The categories of plastics, paper, metals, glass, and the seldom used category ‘organic materials’ in addition to composite materials are now marked on most products to aid recycling and clarify chemical make-up. The codes range from 01 for PET plastic, 22 for paper, 41 for aluminium, and 79 for glass through to 80 and higher numbers for composite or mixed materials. The table also indicates the main uses of the listed material, which includes, for example, in the case of iron (number 40), its use in aerosol cans, tin-plated cans, lids, and staples but that might also include fittings and hinges in wooden crates. Indexed labelling of packaging materials in this manner has been hugely valuable and is responsible for much of the improvement in worldwide recycling and local municipality recycling practice.

1.2.2 Types of Packaging: An Overview and the Basics The primary types of packaging are tinplate, aluminium, plastics, paper and paperboard, glass, and biopolymers but can also extend to wood and wicker or ‘raffia’ materials. The robustness and purity along with costs associated with transport and shipping have a large bearing on selection. Shipping costs are by no means trivial as there is an additional carbon footprint associated with the pollution caused by freighting goods around the globe in addition to the direct paid costs. Division of packaging materials is often performed on a convenient chemical basis; for example, organic and inorganic, natural and artificial/synthetic, porous and solid, or wettable and water repellent. Other suitable

1.2 Survey of Packaging Use

classifications might include flexible and rigid, degradable and non-degradable, or recyclable and non-recyclable. Yet other relevant definitions could also include the malleability or ductility or the thermoforming and thermosetting formulation. In reality, most packaging materials fit into a number of categories and so the classification is by no means straightforward. For example, paper is generally porous, malleable, wettable, and both natural and artificial in terms of its processing history. A representation of the complexity involved in any classification and the diversity of firms or organisations, material, size, and content is given by the vessels shown in Figure 1.1. Packaging used for pharmaceuticals [5, 6], foods [7], and devices has different requirements and yet fulfils the identical overall goal. Table 1.2 Accepted international identity and recycling codes from the American Society for the Testing of Materials D7611 International Resin Identification Coding system, the recycling symbols of the American National Standards Institute, and the European Commission/Union identification of packaging materials for recycling (94/62/EC and 2008/98/EC).

Category

Numerical code

Abbreviation code

Packaging materials(s)

Plastics

01

PET, PETE

Polyethylene terephthalate

Drinks bottles, trays, fibres

02

HDPE

High-density polyethylene

Tough bottles, bags

03

PVC, V

Polyvinyl chloride

Bottles of corrosives

04

LDPE

Low-density polyethylene

Polythene bags, containers

05

PP

Polypropylene

Shampoo, syringes

06

PS

Polystyrene

Cases, Styrofoam

07

OTHER, O

All other plastics (PC, PA, PAN, SAN, bioplastics)

Bottles, biodegradables

08

Paper

Metal

Organic material

Use

Reserved for new materials

09

ABS

Acrylonitrile– butadiene–styrene

Tough coverings, cases

20

C PAP, PCB

Cardboard

Secondary packaging

21

PAP

Other paper

Leaflets

22

PAP

Paper

Labels

23

PBD

Paperboard

Boxes

40

FE

Steel (low-carbon iron)

Aerosol cans, tin-plated steel, lids, staples

41

ALU

Aluminium

Cans, closures, tubes

50

FOR

Wood

Crates, pallets, boxes (Continued)

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Table 1.2

(Continued)

Category

Numerical code

Glass

Abbreviation code

Packaging materials(s)

Use

51

FOR

Cork

Bottle stoppers

60

COT

Cotton

Insulation

61

TEX

Jute, hemp

Sacks, packing

62–69

TEX

Other textiles

70

GLS

Mixed glass, multi-part glass

71

GLS

Clear glass

72

GLS

Green (chrome oxide) glass

Glass bottles, food, medicines

73

GLS

Dark sort glass

74

GLS

Light sort glass

77–79

GLS

Metal-backed glass (Cu, Ag, Au, respectively)

Composites 81

Ca

Mixed media: paper/plastic

Chilled grocery, drinks cartons

82

Ca

Paper and fibreboard with aluminium

Pack liners

90–92

Ca

Plastic and metals

Retortable pouches

95–98

Ca

Glass and metals

Reinforced glass

99

a

C

Other

a) LDPE, LD polyethylene; PA, polyamide; PAN, polyacrylonitrile; PAP, paper; PC, polycarbonate; PET, polyethylene terephthalate; SAN, styrene–acrylonitrile. Numerical and abbreviation codes are also shown in Figure 8.2a(iv).

1.2.2.1 The Meaning of Symbols on Packaging

A single cyclical arrow ( ), a circle based on an arrowed ‘ying-yang’ symbol ( ) found on the product packaging, and the more common centre-filled codified three-arrowed universal recycling symbol ( ) represent an assurance that the producer of that packaging recognises the potential for the material to be reused or reworked (see Table 8.2 and Figure ) as well as the 8.1). The colour, exact form, and size of this triangular symbol ( colour of the background may vary according to the packaging. The meaning of the symbols is given in Table 1.2. The symbols were initially used by the Society of the Plastics Industry (SPI) of the USA (founded in 1937) until it ceased activities under this name in 2010, when the body was renamed. The organisation was rebranded in 2016 as the Plastics Industry Association (PIA) and now sits as the authority on plastic materials, promoting the use of the eight ‘plastics’ symbols that have been adopted globally to aid recycling and recyclability. The RIC and international packaging material codes highlight that the packaging product is made from materials that can be recycled or indicate that any recycling of this material is not available at present. Recyclable plastics with RIC codes

1.2 Survey of Packaging Use

of 1/2/4/5 (mostly polyolefins) are habitually recycled. However, plastics assigned 3/6/7 are rarely recycled, possibly because of the evolution of toxic waste, with category 7 indicating the use of a mixed-medium material (other than polymeric materials 1–6), which is currently inaccessible to recycling practices. Other common groupings of materials are 20–39 for paper and cardboard material, 40–49 for metal material, and 70–79 for glasses (Table 1.2). Other information shown on the pack in recent times can include ‘made from recycled …’ or shows the packaging origins by bearing the caption ‘is made in part or in full from recycled material’. Where only part of the material of the product is based on recycled materials this is often indicated in a manner such as ‘label made from’ or ‘core made from’ in the case of white-lined paperboard. Packaging manufacturers or companies that have a code number from the relevant body such as the Department for Environment, Food and Rural Affairs in the UK or the Ministry of Commerce and Industry in India may use the symbol in the way it is allocated to the product varying by the country holding the licence. Some products also bear on the pack or on the label an indication of other properties of the contents. These can include pictorial indications if the product contains flammable products such as butane, contains pressurised gas, contains toxic products ( ), or may cause infection or irritation. The product packaging also indicates if it is made from compostable materials and therefore is a recognised compostable product, such as the compressed paper egg boxes used in the UK (according to EN 13432). The complex variety of packaging materials [8] used for consumable and non-consumable products serves a multitude of functions, but the primary importance is chemical, microbiological, and physical protection. Current awareness of packaging use, design, and resource utilisation and ultimately of sustainability [9–11] is an important issue and one that defines current, and will increasingly define future, use.

1.2.2.2 Glass Packaging

Washed sand is the main ingredient needed for the fabrication of most types of glass. However, glassy materials produced using only pure silica result in a glass that is too fragile for commercial handling. Consequently, soda (sodium oxide) is added to increase the durability and simultaneously decrease the melting point temperature, making the product easier to handle. Limestone minerals, such as dolomite (calcium carbonate), are incorporated into the sample to increase the chemical resistance of the glass and confer an inertness to a corrosive product. Secondary additions, such as broken pieces of preformed glass (cullet), are further added to this ‘combination’ during production; this is then heated to approximately 1500 ∘ C and shaped into the desired glass packaging. Using broken cullet that has been through certain recycling processes provides technical, environmental, and economic advantages over virgin materials. Glass packaging has a natural gloss and sheen and is smooth and easy to clean or rinse and dry, so it represents a convenient material for many applications. It is also aesthetically pleasing to the eye because it is optically transparent and can be fine-tuned to possess a range of optical properties. Given the high amount of energy required for original manufacture it is convenient that glasses can be both reused and recycled. Many pharmaceutical

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and liquor producers prefer the material because of its inertness and non-reactivity to chemicals but also because of its high gas and water barrier properties, combined with its ability to withstand very high pasteurisation and sterilisation temperatures. The technical properties of glass have also increased as a result of new techniques discovered for cutting, carving, moulding, and surface engraving. Using computer-programmed cutting to form numerous designs, including same strength but lightweight versions of vessels, is now possible. Glass beer bottles account for nearly 55% of glass packaging usage followed by 18% for food, 12% for wine, alcoholic drinks, and liquor, 7% for soft drinks, and others, including pharmaceuticals, which account for only 5%. In the past stoneware, ceramic vessels, or pottery were used for pharmaceuticals, chemicals of medical use (e.g. opium elixir, Epsom salts, cold cream, quicksilver [mercury]), and foods (honey, beers, spirits, ginger beer). However, stoneware is now used as a value-adding tool and to aid product marketing but there are no current forms of medicines making use of pottery. Part of the downfall of ceramics and their replacement with glass is a result of its lower cost in earlier times, e.g. Victorian and pre-Victorian periods. In recent times, the return of stoneware has been used to infer a traditional basis for the manufacture of products (typically beverages and food) and thus extra value. Stoneware-mimicking glasses have now also been made possible by frosting and compounding or pigmenting of the glass, and these have replaced nearly all food uses of ceramic containers. 1.2.2.3 Metal Packaging

Two materials, namely steel sheeting (or aluminium sheeting) and metallic ends, are used to make tinplate metal packaging. Higher grade iron, with less carbon, known as steel, forms the scaffold in the form of sheets that are electroplated with metallic tin to prevent oxidation. A further layer of organic or resinous lacquer is applied to the tin-plated steel; therefore, any direct contact of steel with can contents (usually food) is removed. In this manner, corrosion-resistant metal packages can be mass produced. Can bodies and ends are produced for various types of product such as high-acid, low-acid, and high-sulfur-resistant metal packaging. Other than food products, metal packaging is also used for the packaging of pigments, oils, waxes, paints, and chemical materials. The metal packaging forms a physical barrier, which is resistant to pests (insects and rodents) and also to humidity, light, and air. The thermal resistance of lacquered tin or aluminium cans favours sterilisation and is consequently used as a standard form of packaging. This is certainly the case for foods, where use is common because the can and contents can be heated and simultaneously cooled during retort sterilisation without contamination of the contents. In the modern era, the important factors determining the preference of metal packaging are related to cost, metal abundance, environmental concerns, health concerns, and payments or levies. These have shaped modern production techniques and advances in the sophistication of manufacturing and handling machines used for various forms of container and formats of accessing the contents. As such, the development and wide-scale use of easy-to-open lids, various surface designs, high structural robustness, and the tightness of seams assuring sterility are areas of considerable interest among manufacturers. Probably the most common form of making tin cans (tin-plated steel; cans) is the drawn and redrawn process for steel or aluminium cans, with a ubiquitous example being the standard food can.

1.2 Survey of Packaging Use

The second most common form of making cans involves a DWI process for aluminium or steel cans, with a common example being the thin-walled soft drink or beer can. Other processes include the drawn and ironed (DI) steel can; the shaped aluminium or steel can, e.g. the sardine or pilchard can; the stretch-drawn ironed aluminium or steel can (Toyo ULtimate Can; TULC); and the welded side wall tin-plated steel can. However, because of concerns over toxicity and lack of assurance in seam integrity, ‘soldered’ cans are rarely used in modern times. Additionally, combinations of the above forms of canning vessel may be used to create hybrid products. The frequency of use of the tin can as a routine form of preservation over the last 10–15 years for foods and beverages has seen an observable increase of roughly two times. 1.2.2.4 Paper and Cardboard Packaging

Paper at first appears to be a simple material but this is an underestimation of a complex polymeric resource that has a colourful and extensive history, with the material undergoing many processing revisions and refinements across the centuries. The first paper was constructed from woven and intertwined papyrus reeds and this even pre-dates the well-known originators of wood-pulp paper in north-eastern China. The process of making the ‘modern’ form of paper is thought to date back to the Han Dynasty (200 BCE to 200 CE). A Chinese court official, called Ts’ai Lun, in north-eastern China fabricated fine-grade paper sheeting by improving on an existing process dating from a century prior to his technological advancement. This paper was fabricated from fine-fibre materials, such as mulberry, and the bark from nettles, hemp, and flax. The first recorded use of wrapping paper dates back to 100 BCE with paper made from hemp. The first paper book was dated at 256 CE and by 300 CE paper use was widespread in China and Japan. From about 750 CE paper use was seen to move from China via the ‘silk route’ to the Middle East. At approximately 900 CE paper was found ubiquitously in Egypt with an early form of paper packaging being used for wrapping spices and fruit dating back to 1035. From this point in time, paper use spread to Europe through the Spanish courts in 1085 and then on to the rest of Europe via France. By the late sixteenth century paper production in Europe was well established and there was a more formalised form of paper mill-based production of paper in England, Denmark, the Netherlands, and Russia. In 1844 Friedrich Gottlob Keller and Charles Fenerty began undertaking experiments replacing cotton fabrics and substituting with an exclusive paper made only from wood pulp. Importantly, Henry Fourdrinier, a British engineer, and his brother, Sealy, invented and improved on a prototype of the casting Fourdrinier machine. The paper-making machine changed the process from one of batch fabrication to one where continuous variable sized rolls of paper could be made with ease. The basic raw material for making paper and cardboard packages is the polymer cellulose. Cellulose for paper pulp is usually obtained from specific species of trees and plants, which grow quickly, are easily replaced, and allow the material to be easily mechanically or chemically pulped. Favoured species include the cotton plant, which produces fine-grade paper, and cellulose-rich softwood trees, such as larch, pine, and spruce, or hardwoods, such as birch and poplar. Paper pulp may also be used to create cardboard that does not require the fine-grained structure of refined paper. Both paper and paperboard boxes and cartons are among the most cost-effective ways of packaging goods and have the added advantage of excellent recyclability. Commercial paper and cardboard for packaging applications

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require sound puncture or tear resistance and need to offer the pack contents protection from humidity and light. Corrugated cardboards are produced by two flat paper liners bonded to one another by a corrugated layer called fluting. The three or more layers are glued by a material usually made from maize starch or polymeric water-based adhesive. This gluing function provides the material with strength and unity and enables the material to provide cushioned protection of the encased product against impact from the corrugated layer. Secondary packaging made of corrugated cardboard is very popular among manufacturers. This is mainly because of the cheapness of these packages but also the low weight to high strength ratio that provides adequate protection [4]. Key performance-indicating test methods for packaging include puncture resistance to defy a force that will allow a tool of a specified shape and dimensions to puncture and pass completely through a test specimen. Similar test criteria can be applied to tear and bending deformation and bursting strength resistance along with crush resistance. 1.2.2.5 Wooden Packaging

Commercial wooden packaging is a rarely used commodity in modern times. Despite being one of the oldest packaging materials, its use for foods, pharmaceuticals, and medical devices is now virtually non-existent. A combination of weight, fragility, risk of contamination during transport or reuse, and durability mean its only use is for luxury goods and some fruit or vegetable shipments. Wood used for packaging material is customarily treated with pesticides and insecticides to avoid infestation and to protect its contents. Examples of the persistent use of wood include pallets (for heavy goods), boxes (often for valued products such as tea and coffee), crates (fruit or wine), and barrels (beer, wine, and liquors). 1.2.2.6 Plastic Packaging

The plastic packaging used across the globe is made from processing various products from crude oil and gas. However, only about 5% of global oil resources are used in the production of plastic and an astonishing mere 3.5% of this small amount is lavished on the production of plastic packaging. Plastic can be used for both packaging body and closures and, with the aid of designer input with ever less material, to produce even more packaging. As a consequence of their ductility, malleability (plasticity), and ease of shaping, ‘plastics’ remain one of the most popular classes of materials for universal packaging needs. Plastic use as a ubiquitous packaging material did not start until the 1950s; it gained momentum up to the 1970s and is now globally a matter of prime concern with respect to its ineffective disposal and frequent single use. Acrylonitrile (AN) and its related family of packaging materials are often used when pliability is required. There are many different types of AN-based plastics and synthetic rubbers. Materials in this grouping include acrylonitrile–butadiene–styrene, a terpolymer (three different monomers) with extremely good chemical resistance and flexibility, or the copolymers styrene–acrylonitrile, which is more thermally resistant than polystyrene (PS) alone, and polyacrylonitrile or Creslan 61, which is thermally resistant but also possesses some unique metal-binding properties. On combustion, as part of the energy-recovery processes of waste plastics or thermal recycling because of the acrylonitrile (AN) group

1.2 Survey of Packaging Use

(CH2 =CH–C≡N), the compounds are known to liberate cyanide gas and carbon monoxide. In opposition to AN, polycarbonate (PC) packaging is easy to process, cover, and shape with heat-forming capability. These types of plastic have a wide area of usage in the modern production sector, where toughness and a durable character with respect to impact are required. Consequently, PC plastic is now used for ampoules and ‘plastic glass’ mimics. This polymer is very transparent and light transmitting – actually being better than most types of glass. Water bottles used in homes and babies’ bottles populating nurseries around the globe are made from PC material. The best property of PC lies in its durability to impact, which is why it is also used for prefilled syringes and industrial safety glasses. The PE group of packaging materials represents the single biggest category of plastic used in packaging but also universally across all sectors. Recycled PE is used for milk bottles, medicine bottles, and many general containers and can account for up to 61% of all plastics in the recycling stream. HDPE is a tough, malleable, abundant, and cheap material but its natural opacity due to light scattering means it cannot be used in products where transparency is needed. Nevertheless, it is one of the most widely used plastics of all those that are currently available to manufacturers. HDPE, which is a particularly tough version of PE, is also utilised for tubs used for cheeses and butter and boil-in-the-bag food products and may account for as much as 29% of all plastics. Low-density polyethylene (LDPE) is a semi-opaque, tough, durable plastic but with an elastic, easy-to-cut character. LDPE plastics are used mostly in pack-film materials by virtue of being smooth, elastic, and relatively transparent. LDPE plastics are also routinely used in the manufacture of bags and in the elastic lids of many types of jars. This type of plastic may account for an incredible 32% of all plastics and, along with HDPE, accounts for a significant portion of environmental plastics and micro-plastics. PET packaging, depending on the thermal treatment, is an amorphous (transparent), semi-crystalline (opaque), flexible, and valuable packaging material (representing 9% of all plastics used). Depending on PET film thickness it may be rigid or semi-rigid and this can dictate its possibilities for end use. At a density of around 1.39 g/cm3 (cf. 2.7 g/cm3 for aluminium and about 2.8 g/cm3 for glass) it is a lightweight material that has excellent gas and humidity barrier properties. Simultaneously, it is mechanically tough and highly resistant to impact, making it ideal for bottles such as liquid pharmaceutical containers and carbonated drinks bottles as well as jars and trays. The semi-crystalline form of PET, known as CPET, is used almost exclusively for oven-ready meal trays because of its high thermal resistance. The now common PET bottle was first invented in 1973 but has since spread to use in some ‘plastic cans’ that consist of a transparent or printed PET body and aluminium lid, often with a pull-ring (Minuman, Invento, Lino, and Sino Packaging). The most important advantage of PET usage is that it possesses sound multiple recycling characteristics; consequently, greater use of this plastic presents greater possibilities for more routine plastic recycling. Some recently discovered species of bacteria are thought to be able to digest PET as a food source; this opens up more avenues for improved recycling or disposal by species found in the natural environment that degrade the waxy and wax-like materials. The next cluster of packaging materials includes PP, PS, and polyvinyl chloride (PVC). PP as a packaging material is resistant to chemicals, heat, and moisture. It is a plastic that has moderate rigidity, being used for ketchup bottles, medicine bottles, yogurt pots, and lids. It has the lowest density among plastics used in packaging and accounts for up to

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11% of all plastics. PS packaging can be seen in rigid containers and in expanded insulating foam. In a non-expanded form it is a very tough, highly transparent, and bright plastic used for protective packaging (egg cartons and meat trays) and may account for up to 10% of all plastics. PVC packaging exists in two forms – hard and elastic varieties (constituting 5% of all plastics) – and is often used to make bottles for vegetable oil and shampoo; it is also used in pharmaceutical push-out-packs. PVC was initially discovered by Henri Victor Regnault and later refined for potential use by Eugen Baumann. Approximately 40 years later in 1926 Waldo Semon mixed different additives into PVC to make it more pliable; this resulted in an easier-to-process material and allowed its widespread use (5% of all plastics). Concerns in the 1970s over the vinyl chloride (C2 H3 Cl) monomer (frequently referred to as VCM), bisphenol A ((CH3 )2 C(C6 H4 OH)2 ), and dioxin (dioxin-like compounds, e.g. 1,4-dioxin) present in the material have somewhat spoilt the reputation of PVC as the superpackaging material that it is. From the 1970s, VCM exposure was linked to a rare form of liver cancer, known as angiosarcoma. The US Environmental Protection Agency classified VCM as a known human carcinogen from this time onwards, with factory workers being the most common victims of VCM over-exposure. 1.2.2.7 Composite Packaging

Composite packaging is made from combining at least two different and often physically distinct materials. The goal in combining various materials is to increase the mechanical and chemical properties of the materials over those observed in any single material. Sometimes composite materials also demonstrate unique properties not seen with either individual material through an effective synergism in the physical properties of each material. Commonly used examples include plastic–aluminium composite packaging used for steam retortable pouches; cardboard–PE composite packaging used for Tetra Brik cartons; paper–PE composite packaging, frequently used for medical sachet pouches; plastic–paper–aluminium composite packaging used for UHT sterilised product cartons; and paper–aluminium composite packaging used as the webbing for pharmaceutical push-out packs. In some more modern combinations hemp and flax woven materials are embedded within plastic to produce more rigid materials and a range of contemporary ‘bioplastics’ make use of this composite structure.

®

1.2.2.8 Novel Materials: Bioplastics and Oxo-Degradable Polymers

In recent times, the term ‘bioplastic’ has become increasingly prevalent in packaging industry circles. These substances are innovative polymeric materials that can mimic the properties of conventional plastics. However, these materials are made from products or by-products of raw materials from renewable sources. In many applications, bioplastics can be used as a like-for-like substitute for hydrocarbon-derived plastics. Bioplastics can also be produced from many plant-originated raw materials; notably, starch has a very significant place among them. Cellulose and simple sugars are the other important raw materials for a range of polymers. Bioplastics can be thought of as a viable alternative for a wide range of renewable raw materials derived from simple species for potential packaging uses. At present, and most probably because of societal uptake, their cost

1.2 Survey of Packaging Use

remains two to three times higher than that of conventional materials [12]. Biopolymers currently gathering much interest as alternatives to polyolefins include polycaprolactone, polyamide, polylactic–glycolic acid, polycaprolactone (PCL), and polylactic acid (PLA). Importantly, with regard to the persistence of plastics in the environment and according to European standard EN 13432, these materials can be degraded under particular conditions and reduced to a compost. Although it is currently considered impossible to produce sufficient raw materials to supply the current global need for plastics, even if all possible efforts were put into bioplastics production, their use alongside better recycling could achieve this end. Other materials called oxo-(bio)degradables are produced by methods such as adding biological materials to those polymer materials obtained from petrochemical products. Oxo-biodegradation is a type of degradation resulting from oxidative- and microbe-mediated processes or phenomena in combination or in succession. The emergence of packaging materials made from composites and complex blends of fats and waxes with proteins such as zein (maize) or gluten (wheat) along with starch [13] and chemically modified hydroxypropylor hydroxyethyl-cellulose is becoming commonplace [14] for sheeting and adsorbent hydrogel uses in packaged products. Foam ‘peanut’ insulation (Envirofill) and cushioning transport materials (see Figure 8.6) fabricated from thermoplastic starch for applications where expanded PS was previously used have provided good opportunities for growth as more than 220 million tonnes of plastic are used worldwide each year for these purposes. Starch-based packaging that is often used for secondary packaging includes Bio4Pack (Germany). These bioplastics include starch (corn, pea, and potato) and natural fats (hemp oil, soya oil, etc.). They often make use of blends such as PLA and PCL or on occasion PET and mix this with starch. Starch-based plastics routinely contain sorbitol or glycerol as plasticisers to increase flexibility [15]. Bioplastics still account for a very small proportion of the total plastics market share – approximately 2% of plastic use. Currently obtainable materials include bioplastics such as starch–PLA, called Biotec (Germany); a starch–PET/PE blend, called Plantic ES (Australia); starch–PCL, called Mater-Bi (Italy); starch–(polybutylene adipate-co-terephthalate), called Ecoflex (BASF, Germany); a starch polyester (Bayer-Wolff Walsrode, Germany); a starch polyolefin (Roquette, France); kenaf (Deccan hemp); and a fibre–PLA material (NEC Corp., Japan). Routine use of PET is hoped to be replaced with a sugar cane-derived monoethylene glycol–PET material used for the soft drinks industries called PlantBottle (Dasani/Coca-Cola Company, USA). Thermoplastic starches called Chisso (Japan) and another variant called Envirofill based on an expanded product (DuPont, USA) represent promising new candidate materials. Unfortunately, biopolymers of this type tend to degrade easily at 180 ∘ C and consequently, at present, many are combined with oil-derived plastics from a performance point of view and this informs design strongly [16]. European standard EN 13432 and ASTM 6954 describe the criteria and precisely controlled conditions used in prescribed tests for degradation at 60 ∘ C in order for a material to be considered as biodegradable. The biopolymers suitable for packaging applications [15], including starch, chitin/chitosan, cellulose derivatives, PLA, PCL, poly(butylene succinate), and polyhydroxybutyrate, are discussed in detail in other publications.

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References 1 Risch, S.J. (2009). Food packaging history and innovations. Journal of Agricultural and Food Chemistry 57: 8089–8092. https://doi.org/10.1021/jf900040r. 2 Goldsmith, R.E. (1999). The personalised marketplace: beyond the 4Ps. Marketing Intelligence & Planning 17 (4): 178–185. https://doi.org/10.1108/02634509910275917. 3 Gustavo, J.U., Pereira, G.M., Bond, A.J. et al. (2018). Drivers, opportunities and barriers for a retailer in the pursuit of more sustainable packaging design. Journal of Cleaner Production 187: 18–28. https://doi.org/10.1016/j.jclepro.2018.03.197. 4 Fadiji, T., Coetzee, C., Chen, L. et al. (2016). Susceptibility of apples to bruising inside ventilated corrugated paperboard packages during simulated transport damage. Postharvest Biology and Technology 118: 111–119. https://doi.org/10.1016/j.postharvbio.2016.04 .001. 5 World Health Organization. (2002). Annex 9: Guidelines on Packaging for Pharmaceutical Products. WHO Tech. Rep. Ser. 902: 119–156. 6 Bauer, E.J. (2009). Issues facing modern drug packaging. In: Pharmaceutical Packaging Handbook (eds. R. Coles, D. McDowell and M.J. Kirwin), 493–535. New York: Informa Healthcare.Chapter 12: 7 Coles, R. (2003). Introduction. In: Food Packaging Technology (eds. R. Coles, D. McDowell and M. Kirwin), 1–31. Boca Raton: Blackwell Publishing (CRC Press). Chapter 1: 8 Shin, J. and Selke, S.E.M. (2014). Food packaging. In: Food Processing: Principles and Applications, 2e (eds. S. Clark, S. Jung and B. Lamsal), 249–273. Chichester: Wiley.Chapter 11: 9 Marsh, K. and Bugusu, B. (2007). Food packaging – roles, materials, and environmental issues. Journal of Food Science 72 (3): R39–R55. https://doi.org/10.1111/j.1750-3841.2007 .00301.x. 10 Reisch, L., Eberle, U., and Lorek, S. (2013). Sustainable food consumption: an overview of contemporary issues and policies. Sustainability: Science, Practice and Policy 9 (2): 1–19. https://doi.org/10.1080/15487733.2013.11908111. 11 Raju, G., Sarkar, P., Singla, E. et al. (2016). Comparison of environmental sustainability of pharmaceutical packaging. Perspectives on Science 8: 683–685. https://doi.org/10.1016/j .pisc.2016.06.058. 12 Thakur, S., Chaudhary, J., Sharma, B. et al. (2018). Sustainability of bioplastics: opportunities and challenges. Current Opinion in Green and Sustainable Chemistry 13: 68–75. https://doi.org/10.1016/j.cogsc.2018.04.013. 13 Masmoudi, F., Bessadok, A., Dammak, M. et al. (2016). Biodegradable packaging materials conception based on starch and polylactic acid (PLA) reinforced with cellulose. Environmental Science and Pollution Research 23 (20): 20904–20914. https://doi.org/10 .1007/s11356-016-7276-y. 14 Qiu, X. and Hu, S. (2013). “Smart” materials based on cellulose: a review of the preparations, properties and applications. Materials 6: 738–781. https://doi.org/10.3390/ ma6030738.

References

15 Youssef, A.M. and El-Sayed, S.M. (2018). Bionanocomposites materials for food packaging applications: concepts and future outlook. Carbohydrate Polymers 193: 19–27. https://doi.org/10.1016/j.carbpol.2018.03.088. 16 Betancur-Muñoz, P., Osorio-Gómez, G., Martínez-Cadavid, J.F., and Duque-Lombana, J.F. (2014). Integrating design for assembly guidelines in packaging design with a context-based approach. Procedia CIRP 21: 342–347. https://doi.org/10.1016/j.procir .2014.03.173.

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2 Chemical Engineering of Packaging Materials CHAPTER MENU Introduction, 27 Building Blocks, Extraction, and Raw Materials, 30 Industrial Processes, Wood-Pulping, Processing, and Smelting, 33 Making Glass, 36

Abstract In this chapter packaging materials are considered from a chemical engineering perspective, that is, processes involving the building blocks of certain raw materials, such as ores, and methods of extraction and exploitation. The use of rigorous extraction in industrial processes and its influence on material quality and waste production including scrappage (slag and clinker) follows. Processes including wood-pulp manufacture and ore-smelting are core contributory stages in the fabrication of modern packaging materials. The description of these processes is accompanied by an outline of the manufacture of glass and its use according to its starting materials. The raw materials are used combinatorially in numerous grades and forms of complex and composite-type materials.

Keywords life cycle; extraction; materials; commodities; smelting; haematite; Kraft paper

2.1

Introduction

Raw materials united through a combination of the processes indicated in Figure 2.1a following on from refining, purification, or gradation are able to produce a suitable ‘working material’ for packaging use. The working material may require further adaptation, such as polyethylene (PE) lamination to create better gas or moisture impermeability. Needless to say, such chemistry then creates further waste. The testing that takes place aligns the steps of chemical modification to produce both the working material and various types of waste. Testing has to ensure the correct degree of purity (as befitting the final end use) as well as optimal functionality and performance. Smelting of metals, fractionation

Packaging Technology and Engineering: Pharmaceutical, Medical and Food Applications, First Edition. Dipak K. Sarker. © 2020 John Wiley & Sons Ltd. Published 2020 by John Wiley & Sons Ltd.

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and cracking of crude oil and natural gas sources for plastics, silicate mining for glass, and wood-pulp generation for paper are the usual sources of raw materials. These materials are then moulded and shaped into forms suitable for carrying and retaining a commercial product. Figure 2.1a shows a range of unit operations in the form of an organogram associated with the life cycle of commercial packaging materials. Following adequate screening and refining or purification (particularly when recycled materials are being used), the raw materials are converted into the working material and shaped into the final product. For example, this can be cullet, sand, soda, and lime for glass manufacture. However, as part of the refining process natural waste materials are generated [1]. Some working material may also require chemical modification, such as the embedding of nano-materials [2], the hydroxypropyl derivatisation of cellulose to create polymer for use in biopolymer film packaging [3], or the corona discharge treatment of polypropylene to form carbonyl, carboxylate or amide groups on the surface [4] that aid printing. Working material in the form of assorted designations of various packaging materials produces stock such as multi-lamellar laminate films for a range of adaptations. At this point materials can pass on to manufacturing processes for various applications, such as bottled product or vacuum-packed modified-atmosphere trays [5]. These formed packaging products then pass on to the distribution chain and, either as a result of this distribution and poor storage or as a result of transit damage and natural loss of materials during manufacture, on to accrued waste. Importantly, at all steps of the

Raw materials Refining and purification

Chemical adaptation

Various packaging materials

Various packaging designations

Working material

Manufacturing

Waste Assessment

Various packaging applications

Disposal Distribution chain (a)

Figure 2.1 Packaging materials chemical engineering unit operations. (a) Organogram of unit operations involved in the life cycle of commercial packaging. (b) Raw materials.

2.1 Introduction

RAW MATERIAL FOR PACKAGING

Ores and minerals

Mechanical and chemical processing

Melting: adjuvants (lime, soda, boron)

Boxes, crates, and pallets

Glass

Oil and gas

Refining and distillation

Extraction Starch and gums

Smelting and refining

Pigments and fillers

Plant and animal matter

Wood and wood pulp

Silicates, sand

Acids, gelatin, and proteins

Exudates Waxes and greases

Forming Sheetmaking

Forming Polyolefins

Paper and board Leather

Plain Alloys Natural biodegradables

Moulding Sheetmaking

Dyes

Coloured Forming Synthetic polymers

Metals

Cellulose (b)

Figure 2.1

(Continued)

process from sourcing materials to finished distributed product, assessment of quality and performance is essential. Figure 2.1b shows the five different types of raw materials used for packaging materials. These consist of ores and minerals; silicates and sand; wood and wood pulp; plant and animal matter; and, lastly, oil and gas. The first of these, ores and minerals, are used to

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create pigments, alloys, and pure metals. Silicates and finely ground sand are used to make glass in its various guises. Glass may use some of the pigments taken from ores such as malachite, uranates (luminous glass), cobalt blue, borate, lead, silver, gold, and iron oxides. Wood is used of course to make paper and cardboard but also for direct use in pallets and crates (tertiary packaging). Wood can also be used as a source of cellulose for cellophane and in modern-day bioplastics, which are made from hydroxypropyl methyl or ethyl celluloses (see Sections 3.4 and 3.4.1). Plant and animal materials may include starch and gums for use in paper and bioplastics, proteins, waxes, exudates such as natural rubber or amber, leather, and natural biodegradables. Finally oil and gas are most routinely used to make polyolefins (plastics), waxes, dyes, and synthetic polymers [6]. Figure 2.1b highlights the inter-relationships and end products of the principal sources of raw materials and also of the process aids used in making the packaging. The five starting materials are also sources of key functionalising additives, including pigments, silicates (for paper sizing), natural biodegradable materials, dyes, and the polymers that are used across all packaging media. Smelting of ore is a prime example of taking a crude starting commodity in the form of an inorganic mineral ore and creating an entirely different material. When extracting the metal for direct or indirect further use, this can create many derivative product materials; common examples would be bauxite (aluminium) or haematite–magnetite (iron). High temperatures are needed in this energy-intense and highly polluting fabrication process [7], such as 1560 ∘ C for iron and 660 ∘ C for aluminium (see Table 3.9). Glass-making (discussed in Section 2.4) takes various adjuvants and sand, cullet, soda, and lime and occasionally other compounds such as boric oxide to create a supercooled highly viscous amorphously structured fluid or ‘glass’. Pigments such as cobalt are used to give the glass a blue hue or colour. Wood chips, another starting material, are mechanically or chemically degraded to fabricate paper that, after further bleaching processing, produces white paperboard. Plant and animal matter can be used to harvest cellulose and exudates or proteins [8] that can be used in bioplastics and leather. Finally, crude oil, by processes such as cracking and fractional distillation, is used to create polyolefin plastics such as PE. The breakdown products of the oil and gas industries such as aniline are also used to create a range of nitrogenous azo dyes, such as mauveine (aniline purple), which was invented by William Perkin in 1856.

2.2 Building Blocks, Extraction, and Raw Materials The Earth’s crust and therefore the most valuable ores consist of about 12 or so of the 115 possible elements found in the natural environment, where base metals are present at concentrations much less than 1%. In descending order of abundance for the most common elements these are (percentages are approximate values): oxygen (47%), silicon (28%), aluminium (8%), iron (5%), calcium (4%), potassium (3%), sodium (3%), and magnesium (2%). The most abundant rock minerals in the crust are plagioclase (40%; e.g. diabase), feldspar (12%), quartz (12%), pyroxene (11%; e.g. augite), amphibole (5%), mica (5%; e.g. biotite or muscovite), and clay minerals (5%). A mere 8% of the Earth’s crust is made from

2.2 Building Blocks, Extraction, and Raw Materials

non-silicates, e.g. carbonate rocks such as limestone, the source of lime used in glass and iron manufacture. Obviously, the Earth’s surface or subsurface is not just populated by mineral rocks but also by vegetation and a subterranean source of oil, natural gas, and coal all derived from chemically degraded plant and animal materials. Iron and aluminium ores are among the most common components of the crust, with common iron ores being magnetite, haematite, siderite, goethite, and limonite. More than 95% of iron ores recovered from the crust (mostly magnetite and haematite) are converted to iron and steel. The principal and most abundant aluminium ore component of the crust is bauxite, followed by corundum and cryolite. Common copper ores include copper pyrite, copper glance (chalcocite), and malachite. Tin ores frequently encountered include tin pyrite and cassiterite, but these represent a relatively rare ore in the Earth’s crust. Indonesia and China are two of the more common sources of mined tin ore. Figure 2.2 shows commodities and the raw materials, core ingredients, and fabrication aids used in their manufacture. Iron and steel melt at approximately 1540 ∘ C, for example, and are converted from iron ores though smelting to crude high-carbon cast iron and then through various subprocesses to remove high concentrations of carbon to wrought iron and mild steel. Stainless steel involves mixing mild steel with traces of chromium (see Section 3.3). The basic ingredients for cast iron (pig iron) ingot production are coke (coal), lime, and iron ore; production is usually undertaken in a blast furnace or metallurgical furnace [7] at around 2000–2300 ∘ C. Blast furnaces are also used for metals such as lead or copper. Iron from a blast furnace is typically converted to steel in a process developed by Iron and steel: • Iron ore (principally magnetite ~70% Fe3O4 or haematite ~70% Fe2O3) • Coal • Coke • Limestone (CaCO3) • Scrap iron • Other metals (steel)

Paper: • Wood chips (50% cellulose, 25% lignin) • Sizing agent • Filler • Recycled paper • Other materials • Wax • Plastics

Aluminium: • Bauxite ore (~60% Al2O3) • Caustic soda (NaOH) • Lime (CaO) • Scrap aluminium • Cryolite (Na3AlF6) – electrolyte • Aluminium fluoride (AlF3) aid • Carbon electrode • Other metals (alloys) Plastics*: Plastic pellets/beads Plasticiser Filler Recycled plastic pellets • Other materials • • • •

Glass: Sand Soda ash (Na2O) Lime (CaO) Cullet (broken glass) • Borax • Flint • Other materials

• • • •

Wood: • Soft wood • Hard wood • Staples/nails and screws • Varnish • Wax

Figure 2.2 Commodities and principal types of raw materials used for packaging. *Polyolefins, cellulosics, and rubber.

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Henry Bessemer in 1855, which involves blasting air via tuyère pipes through molten pig iron or using a more expensive electric arc furnace (EAF) process developed in full working form by James Readman in 1888. Melting is accomplished by supplying energy to the furnace interior. This energy can be electrical or chemical. Electrical energy is supplied via the graphite electrodes and is usually the largest contributor to overall powering cost in melting operations. Initially, an intermediate voltage tap is selected until the electrodes bore into the scrap. As the furnace atmosphere heats up the arc stabilises and, once the molten pool of steel is formed, the arc becomes quite stable and the average power input increases. The iron ore blast furnace as the basis for all iron- and steel-making via the production of pig iron is used in a form that is little altered from the original 1855 Bessemer configuration or the simpler format that Abraham Darby used in 1709. At the base of the furnace is a hearth (at 1300 ∘ C); above this portion of the furnace is a zone called the bosh (at 1700 ∘ C), which is the hottest part; at the bosh, molten iron exits the furnace and liquid or gaseous fuel and air are injected via tuyère pipes. The bosh lies below the barrel (at 1500 ∘ C), which ascends up the furnace to the upper portion and to the stack, the throat (at 1000 ∘ C), and finally the flue (at 500 ∘ C). The lining of the blast furnace is constructed from refractory fire bricks that insulate the material and retain a suitable melt temperature in the core of the furnace. Chemical energy is also supplied to the liquid pool of metal via oxygen fuel burners and oxygen lances. Oxygen fuel burners use natural gas mixed with oxygen or a blend of oxygen and air. Heat is transferred to the metal by flame radiation and convection by the hot products of combustion, and heat is transferred within the molten metal by simple conduction. Modern cylindrical blast furnaces can be 20–40 m tall with a maximal width at the base hearth of 5–15 m. Output varies but modern production can make between 1000 and 10 000 tonnes of pig iron per daily campaign. The modern blast furnace process starts with a means of placing the iron ore as a starting point in the furnace with a top-loading filling device, which charges the furnace with coke, iron ore, recycled iron, and limestone. At the base of the furnace is a sage hole to remove waste and a tap hole to extract the liquid pig iron. Waste gases such as carbon dioxide, carbon monoxide, and various sulfurous gases leave via the stack and through the flue gas [7]. There are, in principle, six main types of materials used for packaging materials (Figure 2.2). The main categories are aluminium, steel-iron, glass, paper, plastics (of which there are many types), and wood. Of course, as shown in the figure, the individual types and sourcing for all materials have a large influence on the manufactured end product. Taking wood as an example, there are softwood and hardwood varieties with different grain structures that can be used to produce different types of transport crates, palettes, or shipping boxes as well as different grades of paperboard and paper. With metals, plastics, and glass the background concentration of impurities might be expected to influence the physical and mechanical properties of the material. Copper, for example, incorporated as an impurity in aluminium at 4–6% w/w makes the aluminium stronger; below this, mechanical performance is unaltered from pure aluminium. As basic forms of commodity other than naturally occurring ores and recycled materials the remaining commodities used for packaging include silicate sand as the basis for glasses, crude oil, crude oil-cracking products, natural biopolymers and natural gas for plastics, and wood or straw for paper.

2.3 Industrial Processes, Wood-Pulping, Processing, and Smelting

2.3 Industrial Processes, Wood-Pulping, Processing, and Smelting 2.3.1

Refining Ores

Metals are manufactured from mineral ores. When these are crushed into fine particles and combined with various smelting agents (e.g. limestone flux) at appropriate temperatures, this allows the release of liquid metal (Figure 2.3). The melting point (T m ) of the iron in iron ores (haematite, magnetite) is in the region of 1540–1560 ∘ C [7]. Limestone (CaCO3 ) is converted to lime (CaO), which reacts with silicate in the ore to create iron-contaminated calcium silicate waste (slag or clinker). The ore undergoes three reduction reactions in the furnace and the iron material reacts with carbon monoxide (CO): Top of the furnace at lower temperature (