John murphy additives for plastics handbook elsevier 2001 (1)

Replacement of Heavy Metals Selection of Antioxidants for Use with UV Stabilizers Concentrates, Masterbatches New Chemistry Recent Developments ^ing Specific Properties: Flammability - F

2nd Edition

Additives for Plastics Handbook

2nd Edition

John Murphy

ELSEVIER ADVANCED TECHNOLOGY

Kidlington, Oxford OX5 1GB, UK

USA Elsevier Science Inc, 360 Park Avenue South, New York,

NY 10010, USA

JAPAN Elsevier Science Japan, Tsunashima Building Annex,

3-20-12 Yushima, Bunkyo-ku, Tokyo 113, Japan

Copyright © 2001 Elsevier Science 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, electrostatic, magnetic tape, mechanical, photocopying, recording or otherwise, without permission in writing from the publishers

Published by

Elsevier Advanced Technology,

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CONTENTS

List of Tables xvii List of Figures xxi

Preface and Publishers' note xxiii

Chapter 1 An Overview of Additives 1

Chapter 2 Types of Additive and the Main Technical Trends 5

2.1 Current Lines of Development 5

2.1.1 Fillers 6 2.1.2 Pigments 7 2.1.3 Plasticizers 7 2.1.4 Stabilizers 8 2.1.5 Flame retardants 8 2.2 Special Additives 9

2.2.1 Antistatic and conductive additives 9 2.2.2 Food contact and medical additives 9 2.2.3 Clarifiers, nucleating agents, compatibilizers 10

2.3 Multi-functional Formulations 10

2.4 Masterbatches 10

2.5 Dendritic Polymers 11

Chapter 3 The World Market 13

3.1 World Consumption of Additives 13

3.2 The Market for Masterbatch 15

3.3 Overall Commercial Trends 15

3.4 Growth of Specialist Compounders 16

3.5 Regional Factors 16

Chapter 4 Modifying Specific Properties: Mechanical Properties - Fillers 19

4.1 Effect of Fillers 21

4.1.1 Mechanical properties 21 4.1.2 Thermal properties 21 4.1.3 Moisture content 21 4.1.4 Reinforcement mechanism of fillers 21

4.3.1 4.3.2 4.3.3 4.3.4 4.3.5 4.3.6 4.3.7 4.3.8 4.3.9

Calcium carbonate Kaolin

Magnesium hydroxide (talc) WoUastonite

Silica Metal powders Microspheres Expandable microspheres Cellulose fillers

Surface Modification 4.4.1

4.4.2

Particle geometry Coating

Nano-technology 4.5.1 Processing nano-composites Commercial Trends

4.2 Factors for Compounding 22

4.2.1 Aggregation of fillers 23 4.3 Types of Fillers 24

32 4.6 Commercial Trends 35

Chapter 5 Modifying Specific Properties: Mechanical Properties

5.2.2 5.2.3

5.2.4 5.2.5 5.2.6

Aramid fibres Carbon or graphite fibres Glass fibre

5.2.3.1 E-CRglass 5.2.3.2 Other developments 5.2.3.3 Forms of glass fibre 5.2.3.4 Chopped/milled products Polyester fibre

Polyethylene fibre Hybrid fibres Other Fibres

5.3.1 5.3.2 5.3.3

Asbestos fibre Boron fibre Nylon fibre Natural Fibres Forms of Reinforcement Long-fibre Reinforcement New Developments 5.7.1

5.7.2 5.7.3

Polyurethane/long fibres ABS/long fibres

Shaped fibres Commercial Trends

Chapter 6 Modifying Specific Properties: Appearance - Colorants, Pigments,

Dyes, Special Effects 57

6.1 Main Types ofPigment and Colorant 58

6.1.1 Mixed metal oxides 58 6.1.2 Dyes 58 6.1.3 Liquid colours 59

6.2 Addition of Colorants 60

6.3 Replacement of Cadmium 61

6.4 Pigments for Special Effects 62

6.4.1 Aluminium pigments 63 6.4.2 Pearlescents 63 6.4.3 Light interference pigments 63

6.4.4 Fluorescents 64 6.4.5 Thermochromic and photochromic pigments 64

6.4.5.1 Intelligent' heat protection for

food products 65 6.4.5.2 High-performance dyes for CD

manufacture 65 6.4.5.3 Solar heat 65 6.5 Laser Marking 66

6.6 Pigment Dispersants 66

6.7 Multi-functional Systems 67

6.8 Pigments for Engineering Plastics 67

6.9 The Effect of Pigments on Dimensions 6 8

6.10 Colorants for Food and Medicals 69

6.11 Recent Developments 69

6.11.1 Colour strength 69 6.11.2 Weathering 69 6.11.3 Natural effects 70 6.11.4 New forms of pigment 70 6.11.5 Surface treatment 70 6.11.6 New pigment chemistry 70 6.12 Market Trends 71

Chapter 7 Modifying Specific Properties: Appearance - Black and White

Pigmentation 73

7.1 Types of White Pigment 73

7.1.1 Titanium dioxide 7 3

7.1.1.1 Surface treatments 74 7.1.1.2 Titanium dioxide grades 76 7.1.1.3 Opacity and tinting strength 7 6

7.1.1.4 Colour 78 7.1.2 Zinc sulphide 78 7.1.3 Other white pigments and extenders 8 0

7.1.3.1 Aluminium silicates 80 7.1.3.2 Barium sulphate ('blanc fixe') 80

7.1.3.3 Calcium silicate 80 7.1.3.4 Magnesium silicate 81 7.1.4 White masterbatch 82 7.1.5 New developments 82 7.2 Black Pigments 84

7.2.1 Types of carbon black 84

7.2.1.1 Thermal oxidative decomposition

processes 85 7.2.1.2 Thermal decomposition processes 8 6

7.2.1.3 Effect of particle size and structure

on properties of carbon blacks 8 6 7.2.1.4 Testing for properties: structure -

effect and determination 8 7 7.2.2 Other black pigments 89 7.2.3 Black masterbatch 90 7.2.4 Recent developments 91 7.3 Commercial Trends: Titanium Dioxide 92

7.4 Commercial Trends: Carbon Black 92

Chapter 8 Modifying Specific Properties: Resistance to Heat - Heat

Chapter 9 Modifying Specific Properties: Resistance to Light - UV Stabilizers 107

9.1 How They Work 107

Replacement of Heavy Metals 8.4.1 Organotins Effect of Silica on the Activity of Stabilizers Benzoxazolone Derivatives for PVC New Chemistry for Stabilizers 8.7.1 Lactone chemistry 8.7.2 Vitamin E

Recent Developments 8.8.1 Pipes and fittings 8.8.2 Foamed pipe 8.8.3 Cable insulation 8.8.4 Medical products Other Stabilizers

Commercial Trends

Replacement of Heavy Metals Selection of Antioxidants for Use with UV Stabilizers Concentrates, Masterbatches

New Chemistry Recent Developments

^ing Specific Properties: Flammability - Flame Retardants

How They Work Summary of FR additives 10.2.1 Reactive FRs 10.2.2 Additive FRs

10.2.2.1 Inorganics Halogenated Compounds 10.3.1 Chlorinated compounds 10.3.2 Brominated compounds Other Flame Retardants

10.4.1 Melamine cyanurate (MC) 10.4.2 Zinc borate

10.4.3 Zinc hydroxystannate (ZHS) and zinc

stannate (ZS) 10.4.4 Zinc sulphide 10.4.5 Metal hydrates Phosphorus

Intumescent Flame Retardants Halogen-free Systems

10.7.1 Wire and cable compounds Combinations of Flame Retardants Synergistic Reactions

10.10 Health and the Environment

11.3 ESD (Electrostatic Discharge) Compounds 144

11.4 EMI (Electromagnetic Interference) Compounds 144

11.5 Metallic Additives 144

11.6 Coated Polymers 147

11.7 Intrinsically Conductive Materials 148

11.8 Moulded Circuitry 148

11.9 Recent Developments 149

Chapter 12 Modifying Processing Characteristics: Curing and Cross-linking 151

12.1 The Curing Process 151

12.2 Terminology 152

12.3 Curing Agents, Accelerators 152

12.4 Inhibitors 153

12.5 Curing with Accelerators 154

12.6 Curing without Accelerators 154

12.7 Selecting a Curing System 155

12.8 Curing Agents for Epoxy Systems 157

Chapter 14 Modifying Processing Characteristics: Plasticizers 169

14.1 The Function of Plasticizers 169

14.2 Main Types of Plasticizers 170

14.2.1 Phthalates 170 14.2.2 Sebacates and adipates 171

14.2.3 Fatty acid esters 171 14.2.4 Oligomeric/polymeric plasticizers 172

14.2.5 Epoxies 173 14.3 Extenders and Secondary Plasticizers 173

14.4 Health and Safety of Plasticizers 173

14.5 Reducing the Level of Plasticizers 174

14.6 Recent Developments 175

14.7 Commercial Trends 175

Chapter 15 Modifying Processing Characteristics: Blowing Agents 177

15.1 The Function of Blowing Agents 177

15.2 Physical Blowing Agents 178

15.3 Chemical Blowing Agents (CBAs) 179

15.4 Structural Foams 180

15.4.1 In-house gas generation 181 15.4.2 Nucleating agents 181 15.4.3 Dispersion agents 181 15.5 Syntactic Structural Foam 181

15.6 Replacement of CFCs 182

15.6.1 Flexible foams 183 15.6.2 Rigidfoams 183 15.6.3 Pentane 184 15.6.4 Expanded polystyrene 185

15.6.5 Economics of CFC replacement 186 15.6.6 Testing the insulation value of blowing agents 186

15.7 New Developments 186

15.7.1 Liquid carbon dioxide 187

Chapter 16 Modifying Processing Characteristics: Modifiers and

Processing Aids 189

16.1 Impact Modification 189

16.1.1 Impact modifiers for PVC 190

16.1.1.1 MBS modifiers 190 16.1.1.2 ABS modifiers 190 16.1.1.3 Acrylic modifiers 191 16.2 Elastomer Modification 192

16.2.1 Acrylic rubber 193 16.2.2 Styrenics 193 16.2.3 Polyolefins 194 16.2.4 Polybutene 195 16.3 Dimer Acids 195 16.4 Calcium Carbonate 196

16.5 Modification of CPEE Polymers 196

16.6 Modification of PMMA with Silicon and Phosphorus 197

16.7 Impact Modifiers for Thermosetting Resins 197

16.8 Processing Aids 198

16.8.1 Low-temperature flexibility 200 16.9 Clarifying/Nucleating Agents 200

16.10 Fluoropolymers 202

16.11 New Developments 203

16.11.1 Core-shell rubbers 203 16.11.2 Silicones 204 16.11.3 Modification of engineering thermoplastics 204

Chapter 17 Modifying Processing Characteristics: Lubricants^ Mould Release

Agents, Anti-slip and Anti-blocking 205

17.1 Lubricants for Performance Improvement 205

17.2 Lubricants as Processing Aids 206

Metallic stearates Hydrocarbons Fatty acid amides and esters Polyolefin waxes

Polyamides Fluoropolymers

17.2.8 Silicones 212 17.2.9 Boron nitride 213 17.3 Combination and Modification 213

17.4 Release Agents for Thermosets 214

17.5 Anti-blocking, Anti-slip Additives 216

17.6 New Developments 216

Chapter 18 Other Types of Additive: Miscellaneous Additives 219

18.1 Anti-bacterials and Biocides 219

18.1.1 Anti-allergy agent 221 18.2 Degradation Additives 221

18.3 Shrinkage Modifiers, Low-profile Additives 222

18.4 Improved Barrier Properties 222

18.4.1 Gas barrier coating 223 18.4.2 Resorcinol additives 223 18.4.3 Plasma technology 224 18.4.4 Oxygen absorption in food packaging 224

18.5 Hard Coatings 225

18.6 Thermal Insulation 22 5

18.7 Fragrance 226 18.8 PVC Matting Agent 226

18.9 Anti-fogging 226

18.10 Acoustic Insulation 227

18.11 Surfactants, Foam Control Additives 228

18.12 Mould Treatment Agents 229

Chapter 19 Other Types of Additive: Additives for Rubber 231

20.3.1 Fibres/compatibilizers/impact modifiers 239 20.4 Desiccants 239

20.5 PE/PVC Compatibilizing 240

20.6 Melt Flow/Viscosity Modification 240

20.7 Additives for Identification of Plastics 241

20.8 Equipment for Recycling 244

Chapter 21 Background Information: Equipment - Mixings Compounding^

and Dosing 245

21.1 Incorporation of Additives 245

21.2 Mixing Thermosets 246

21.3 Mixing Thermoplastics 247

21.3.1 Drymixers 247 21.3.2 Calendering 248 21.3.3 Extrusion compounding 248

21.3.4 Compounding mineral fillers 249 21.3.5 Fine talc masterbatch 249 21.3.6 Single- and twin-screw extruders 250

21.3.7 Adjustable screw geometry 251 21.4 Colour Dosing 252 21.5 Recent Developments 253

Chapter 22 Background Information: Health and Safety 257

22.1 Hazards by Additive 257

22.1.1 Carbon black 257 22.1.2 Titanium dioxide 258 22.1.3 Flame retardants 259 22.1.4 Glassflbre 259 22.1.5 Styrene monomer 2 59

22.1.6 Isocyanates 260 22.2 Hazards During Production, Storage, and

Transportation (Workers) 260 22.2.1 Fire/explosion 261 22.2.2 Emissions 261 22.2.3 Skin/body contact 261

22.2.4 Dust 262 22.3 Hazards During Use (Direct Consumer and General

Public) 262 22.3.1 Toxicity-food contact 263

22.3.2 Flame retardants 263 22.3.3 Plasticizers 264 22.4 Hazards During Disposal (Workers and General

Public) 266 22.4.1 Landfill-heavy metals 266

22.4.2 Incineration 267 22.5 HealthandSafety at the Workplace: Some Guidelines 267

22.5.1 Reduction ofemissions at the workplace 268 22.6 New Developments: Solvents 268

Chapter 23 Background Information: Legislation and Testing 269

23.7 Moves to Establish a Threshold of Regulatory

Concern (TRC) 2 76 23.7.1 US history 276 23.7.2 European history 2 76

23.8 The User's Viewpoint 2 77

23.9 Medical Products and Packaging 2 77

23.10 Waste and Recycling 277 23.10.1 Packaging 278 23.10.2 Electrical and electronics 2 78

23.10.3 Automobiles 279 23.11 Physical Testing 279 23.11.1 Mechanical tests 280

23.11.1.1 Tensile strength and modulus 280 23.11.1.2 Flexural strength and modulus

(ISO 178 and ISO 3597) 280 23.11.1.3 Compressive strength (ISO

3604) 280 23.11.1.4 Shear strength 281

23.11.1.5 Impact strength 281 23.11.2 Thermal testing 282

23.11.6.1 Calorificvalue: ISO 1 7 1 6

-calorific value of materials 286 23.11.6.2 Flamespread 286 23.11.7 Smoketests 287

23.11.7.1 AS 1530: Part 3 - t e s t for early

fire hazard properties of materials 288 23.11.7.2 DIN 4102 Part 1 - B l -

Brandschacht test 288 23.11.7.3 VDE 0472 Part 804 288 23.11.7.4 FAR Part 2 5: Federal Aviation

Regulations for materials used in aircraft 288 23.11.8 Fire tests for building materials 288 23.11.9 Combustibility 289 23.11.10 Floor covering 290

23.11.11 23.11.12 23.11.13

23.11.14 Database

New developments Analysis

Surface quality tests 23.11.13.1 Barcol hardness test 23.11.13.2 Acetone sensitivity 23.11.13.3 Surface analysis Colour testing

Standards and Testing Institutions 302

Recommended Books and Journals 303

Manufacturers'handbooks 303 Journals covering additives for plastics and rubber 304

Appendix C: Standard Abbreviations for Plastics and Elastomers 307

Appendix D: Trade Names 311

Curing, cross-linking agents 417 Property modifiers, processing aids 420 Plasticizers 423 Blowing Agents, Dispersants, Miscellaneous Additives 428

Lubricants, release agents, slip/anti-block 430

Editorial Index 445

Index of Advertisers 471

LIST OF TABLES

Table 1.1 Types and uses of additives

Table 1.2 The main effect of additives on the properties

of a compound Table 1.3 Main types of additive for plastics, and their

functions Table 3.1 World production and consumption of major

thermoplastics, 1999-2005 (thousand tonnes) Table 3.2 Regional production and consumption of

thermoplastics, 1999-2005 (% of total) Table 3.3 Recent mergers and takeovers in the additives

sector, 1997-2000

14

17

17 Table 4.1 At a glance: fillers

Table 4.2 Common fillers and reinforcements for plastics

Table 4.3 Some properties of silica particles and the

amounts of added silanes for surface treatment Table 4.4 Properties of a nano-composite P A6 compound,

compared with conventional reinforcement Table 4.5 Polypropylene nano-composite made by a

slurry process compared with conventional compounds

Table 4.6 Physical properties of nano-tubes in

Table 5.1 At a glance: fibre reinforcements 3 7

Table 5.2 A quick guide to the relative properties of fibres 3 9

Table 5.3 Comparison of commonly used reinforcing fibres 40

Table 5.4 Typical properties of continuous pitch-based

carbon fibres (based on BP Amoco Thornel grades) 42 Table 5.5 Typical properties of continuous P AN-based

carbon fibres (based on BP Amoco Thornel grades) 42 Table 5.6 Main properties of glass fibre 44 Table 5.7 Glass fibre: comparison of E-and E-CR glass 45

Table 5.8 Long fibre-reinforced thermoplastics: effect of

fibre length Table 5.9 Properties of typical long-fibre thermoplastic

compounds Table 5.10 Long-fibre plastics compared with die-cast

metals (2 3°C) Table 5.11 Cost comparison between glass fibre and carbon

fibre, specific mechanical properties (glass cost = 1.00)

Table 5.12 Capacities for carbon fibre, worldwide,

1996-2000 (tonnes) Table 6.1 At a glance: pigments, dyes, special effects

Table 6.2 Replacements for cadmium pigment

master-batches Table 6.3 Influence of pigment type on dimensional plates Table 7.1 At a glance: white pigments

Table 7.2 Melt flow index of polycarbonate, pigmented

with 5% Ti02 showing the effect of various surface treatments

Table 7.3 Comparison of the hardness of pigments

Table 7.4 Zinc sulphide compared with titanium dioxide

for glass-reinforced thermoplastics Table 7.5 Properties of white pigments and fillers

Table 7.6 Typical grades of white masterbatch

Table 7.7 At a glance: black pigments

Table 7.8 Effects of changing particle size or structure on

specific peoperties of carbon black Table 7.9 Effects of changing both particle size and

structure on specific peoperties of carbon black Table 7.10 Variations in carbon black produced by

different processes Table 7.11 Typical grades of black masterbatch (universal) Table 8.1 At a glance: heat stabilizers

Table 8.2 Polymer heat stabilizers: selection guide

Table 8.3 Stabilizer systems in different PVC applications Table 8.4 Extrusion compound for window profiles;

comparison between a classical lead formulation and tin maleate (Thermolite 410) Table 8.5 Flexible PUR foam scorch evaluation: delta E

after microwave test Table 8.6 Effect of the structure of HAS on the colour

strength of a compound Table 8.7 World consumption of stabilizers (thousand

tonnes) Table 9.1 At a glance: UV stabilizers

Table 9.2 UV stabilizers: selection guide

Table 9.3 Typical UV stabilizing systems in masterbatch

form 113 Table 10.1 At a glance: flame retardants 115

Table 10.2 Summary of the main FR additives 116

Table 10.3 Eff'ectofchlorinatedFR additives on PE and

PP compounds 121 Table 10.4 Effect of varying ratios of chlorine and bromine

on ABS compounds 123 Table 10.5 Effectofindividualfillers (UL 94 test ofPP) 126

Table 10.6 Influence of intumescent gel coats on fire

behaviour of composites (RTM process) 12 7 Table 10.7 Examples of halogen-free flame-retardant

grades (M A Hanna Group) 128 Table 10.8 General wire and cable specifications to meet

BS7211 129 Table 10.9 Effect of a mineral filler/melamine combination

with PP on LOT and UL 94 tests 131 Table 10.10 FR formulations using various synergists 132

Table 10.11 Halogen compounds found effective with

antimony oxide 134 Table 10.12 Flame retardants: selection guide 135

Table 10.13 Cost and properties of flame-retarded PP 138

Table 10.14 ConsumptionofFRsby major region 139

Table 10.15 ConsumptionofFRsby type and region, 1998

(thousand tonnes) 139 Table 11.1 At a glance: anti-static/conductive additives 141

Table 11.2 Classification of electrical insulation/

conductivity 142 Table 11.3 Performance of stainless steel fibres at various

loadings 147 Table 11.4 Comparison ofdifferent conductive systems 147

Table 12.1 At a glance: curing systems 151

Table 12.2 Applications of organic peroxides 152

Table 12.3 Cross-linking with peroxides: dosage of

peroxide per 100 parts polymer 153 Table 12.4 Curing systems and when/where to use them 155

Table 12.5 Curing agents for epoxy resins 161

Table 12.6 General specifications for BS7211 163

Table 12.7 Advantages and disadvantages of available

cross-linking methods 164 Table 12.8 Use of radiation-cured products in the USA,

1989-2003 (tonnes) 165 Table 13.1 At a glance: coupling, compatibilizing agents 168

Table 14.1 At a glance: plasticizers 169

Table 14.2 Main types of plasticizers 170

Table 15.1 At a glance: blowing agents 177

Table 15.2 Blowing gases for plastics 178

Table 15.3 Typical processing temperatures for

thermoplastics 180 Table 15.4 Replacement of blowing gases for expanded

polystyrene 186 Table 16.1 At a glance: process modifiers and processing

aids 189 Table 16.2 A quick guide to impact modifiers 191

Table 16.3 Kraton G as a compatibilizer 194

Table 16.4 Typical processing aids 199

Table 16.5 Clarified polypropylene compared with other

transparent packaging materials 202 Table 16.6 Eff'ectsofPPA-l onprocessability ofHDPE

resins (capillary rheometry 190°C) 203 Table 17.1 Typical lubricants for various thermoplastics 205

Table 17.2 Characteristics of acrylic processing aids 209

Table 17.3 Effect of an internal lubricant on injection

moulding of electrical housing and cap 210 Table 17.4 Typical high-slip and anti-blocking

masterbatches 215 Table 18.1 Acoustic properties of some commonly used

materials 228 Table 19.1 Additives used in rubber compounding 2 32

Table 20.1 At a glance: additives for recycling 2 37

Table 20.2 Forms of waste, processing lines and potential

recycled products 243 Table 22.1 Typesof additives and their potential hazards 2 58

Table 23.1 Summary of relevant environmental

legislation 2 70 Table 23.2 German BGA limit values for migration of

elements from raw materials (DIN 53 7 70) 2 74 Table 23.3 Permissible migration in toys (European Norm

EN 71-3) 274 Table 23.4 A guide to food-contact additives 2 75

Table 23.5 Tests designed mainly for rigid materials 285

Table 23.6 Tests designed mainly for flexible materials 285

Table 23.7 UL 94 requirements 287

Table 23.8 EC classification of fire tests for construction

products 291

LIST OF FIGURES

Figure 2.1 Acting like a plastic 'sponge', Accurel is one

of the new systems for introducing additives homogeneously to a granular compound

(Photograph: Akzo Nobel) 6 Figure 2.2 Many types of additives, such as stabilizers,

are now supplied in forms that are easier and safer to handle and use (Photograph:

Akcros Chemicals) 8 Figure 4.1 A typical compounding line for reinforced

thermoplastics (Illustration: FTP Co) 22 Figure 5.1 Polypropylene is reinforced with chemically

coupled glass fibre for injection moulding this Whirlpool washing machine tub, giving high performance for low cost

(Photograph: Ticona) 38 Figure 6.1 Structures of inorganic pigments:

(top) rutile-cassiterite structure of inorganic colour pigments and (bottom) the spinel structure (Illustration: Ferro Corporation) 59 Figure 7.1 Diagram of carbon black molecules illustrates

how the size and structure influence the processing and properties

(Illustration: Cabot Corporation) 8 5 Figure 11.1 Carbon black additives can also conduct

electricity, offering a simple and effective means of providing anti-static properties

Figure 17.1 With an average particle diameter of 4.5 /xm,

Tospearl is an advanced silicone anti-blocking agent

(Photograph: GE Silicones) 217 Figure 21.1 For better compounding efficiency, recent

barrier screw designs by Davis-Standard include (top) DSB-V, with variable-pitch barrier flight, and DSB-V I, with a dual-barrier design and variable lead barrier flight (Photograph: Davis-Standard) 2 52 Figure 21.2 Powerful shearing and homogenizing of

sensitive materials, retaining vital rheological properties, is provided by Farrel Corporation's Advex (Photograph: Farrel Corporation) 2 53 Figure 21.3 Looking towards a new market demand, the

Davis-Standard Woodtruder combines in a single system the latest plastics extrusion technology with technology for processing wood fibre (Photograph: Davis-Standard) 2 54

Both technically and economically, additives form a large and increasingly significant part of the polymer industry, both plastics and elastomers In the five years since the first edition of this handbook, there have been wide-ranging developments, covering the chemistry and formulation of new and more efficient additive systems and the safer use of additives, both by processors in the factory and, in the wider field, as they affect the general public

It has also become clear that, to meet today's requirements, the budgets for research and development and the structure needed to maintain a global presence are beyond the resources of individual companies, resulting in many mergers and takeovers, leading to the creation of a few world-scale giant producers, complemented by a number of specialists

This second edition follows the successful formula of the first, presenting a comprehensive view of all types of additives, concentrating mainly on their technical aspects (chemistry/formulation, structure, function, main applications) with notes on the commercial background of each Whereas reports concentrate

on only one sector (such as pigments or 'performance' additives), in this handbook we have again expanded the field to include any substance that is added to a polymer to improve its use, so including reinforcing materials (such as glass fibre), and carbon black and titanium dioxide

As with the first edition, this information is again presented in a more friendly' form, starting from the information requirement of the user, and so classifying additives by the properties that they offer and the appUcations in which they are used To avoid excessive cross-referencing, there may be some repetition, but it is hoped that the advantages of this form of presentation will outweigh any disadvantage

'user-JSM, June 2001

Publishers' note

Sadly, just before completion of this book the author, John Murphy, passed away Elsevier Advanced Technology has endeavoured to complete this work to John's very high standards We hope that Additives for Plastics Handbook will live up to John's expectations and prove to be an invaluable aid

Adding value

to polymers

Slip & Antiblocking

Fatty Acid Amides Amides Concentrates

Antistatic

Fatty Amine Ethoxylates Fatty Amide Ethoxylates Glycerolmonosteatate Sodium Alkane Sulphonate Concentrates

CHAPTER 1

An Overview of Additives

From the very beginnings of the plastics industry, it has been necessary to add materials to a basic polymer resin in order, at least, to make it processable It has also been clear that additive materials are necessary to modify a resin, to improve properties that are desirable, and to eliminate or mitigate properties that are undesirable In developing additive systems, the plastics industry has learnt much from the earlier experience of the rubber industry, but the pace of development responding to market needs has produced research in completely new fields, developing additive systems using new chemistry

While the plastics industry is a major user of additives, it is not the only one Additives overall can be classified as follows:

Table 1.1 Types and uses of additives

Type Main applications

Products, normally used in small quantities, which enhance the value

of materials such as plastics, paints, colour prints, and lubricants, by improving their processability, performance, and appearance during manufacture and in use

Substances that prevent the growth of microbes and give consumer products such as soaps and toothpastes a medicated property

The broad term for paints, inks, and lacquers While often associated with decoration, coatings also protect surfaces from corrosion and damage

Can be soluble dyes for textiles, leather, paper, or insoluble pigments for plastics, coatings, and printing inks

Highly complex functional intermediates or ingredients for 'high-tech' applications; for example, in the pharmaceutical, agrochemical, and electronic industries

Additives that prevent the degradation of plastics and coatings under the effects of heat, oxygen, and light

Chemicals which impart whiteness to textiles, detergents, paper, fibres, and plastics

Type Main applications

in electronic or graphic materials

Colorants that remain undissolved before, during, and after application: they are used to colour plastics, inks, paints, and synthetic fibres

Hardening of coatings and adhesives by means of ultraviolet light Help purify water for industrial and domestic applications They also modify water as an agent for the processing of minerals and oils, and have a variety of properties to process water (for example, flocculants separate water from solid particles)

Source: Ciba Specialty Chemicals

For plastics, the range of additives is very large, involving the improvement of many properties:

Table 1.2 The main effect of additives on the properties of a compound

powdered aluminium

or copper

++

++

=

carborundum

silica, molybdenum disulphide

-Chopped glass

++

++

+ + ++

++

+ + + + ++

powdered

or flaked glass

++

++

+ +

-

-++

-=

Metallic fillers or alumina

-= -

=

=

= -

= -

++ + + + + Key: - decreases;

++ increases;

= essentially no effect

Table 1.3 Main types of additive for plastics^ and their functions

Type Examples Functions

Calcium carbonate, talc, mica Fillers and

mineral

reinforcements

Fibre reinforcements Aramid, carbon, glass,

natural fibres Colorants

Black and white

Carbon black, titanium dioxide

Antioxidants and stabilizers

UV stabilizers

Reactive, additive, other systems

Antistatic/conductive additives

Accelerators, curing agents, and catalysts

Forming cross-links between suitable polymer and other molecules

Mainly phthalates, but many systems are used

Lubricants and plasticizers, nucleating agents Inert gas or gas-forming chemicals injected or mixed into a compound to react during processing

Lubricants, mould release agents, slip and anti-block

Barrier properties, shrinkage, acoustics, surfactants, antimicrobials Impact modifiers, stabilizers

Adding bulk to a compound: increasingly used to improve stiffness, surface hardness Mechanical strength: used as short fibre, long fibre, spheres Virtually unlimited, added as powders or liquids: easier mixing, replacement of heavy metals Also for improved UV resistance and (carbon black) electrical conductivity

Act to delay/prevent oxidation of polymer under heat, during processing or application Delay/prevent oxidation of end-product under prolonged exposure to sunlight Prevent ignition of polymer, promote extinguishing: types not producing smoke or fumes Increase electrical conductivity,

to prevent electrostatic discharge, sticking/clinging (e.g films) Initiate and control the cure of thermosetting resins Cross-linking agents for thermoplastics; coupling agents, compatibilizers to promote bonds between polymers and additives Improvement in processability, flexibility: used mainly in PVC, but limited use in other plastics Improvement of mixing/blending; control of viscosity

Production of foams and expanded plastics; replacement of

chlorofluorocarbons (CFCs)

Improvement in processing; release properties; reduced slippage and blocking with films Giving specific properties

Used to improve/protect properties

of waste plastics during mechanical recycling

CHAPTER 2

Types of Additive and the Main Technical Trends

Additives are becoming more technical, doing more work, offering greater value, and so commanding a higher price PVC is still by far the largest user, in volume terms, but polyolefins have emerged as a growing second-runner and the development of engineering plastics has opened up a fast-growing market for speciality additives, ranging from flame retardants to stabilizers, pigments, and processing aids that will resist the higher processing and service temperatures involved These naturally impose more critical performance requirements

Many additives have more than one effect on a plastics compound Plasticizers will often aid in processing and lubrication Light stabilizers also have an effect of weathering Carbon black, which is widely used as a pigment, also functions as a light shield, as an electrically conductive component, and as a reinforcement

2.1 Current Lines of Development

A main line of development now is multi-functional additives, such as reinforcing fillers: talc is added to polypropylene to improve stiffness and heat stability, pigments can aid in UV protection, plasticizers also function as lubricants and anti-static agents A potentially fertile field is that of synergism between components, where better performance in vital properties such as weathering and flammability can be achieved by using lower concentrations of synergistic additives

The aim, all along, is to simplify operations at the compounding or processing level and to remove the need for precision weighing and metering of very small amounts Delivery of additives in a more convenient and safer form is also high

on priority lists This obviously calls for significant research and development budgets and capital expenditure in more sophisticated production/processing plants, which has the effect of raising the entry cost all the time for new producers A further cost pressure is the necessity of complying with legislation, often worldwide - and to be able to provide customers right down the line with documentation to prove compliance

There is also active development of surface-modification technology, to render fillers of all types (especially inexpensive mineral fillers) more acceptable

Figure 2.1 Acting like a plastic 'sponge', Accurel is one of the new systems for introducing additives homogeneously to a granular compound (Photograph: Akzo Nohel)

to the matrix and improve interfacial bonding, for better, more durable mechanical properties

A third major line of development is to meet increasingly strict regulations for health and safety, both in the workplace and in public use This particularly affects flame retardants (where concern has been expressed about possible escape of flame-retardant components during storage, under heat and flame, and

in recycling) and pigments (where legislation has centred on the use of heavy metals in pigment formulations, possibly creating hazards in disposal of the product)

2.7.7 Fillers

Filler technology is shaping an entirely new and 'active' role for these very traditional materials, especially using coating and other surface treatments to confer other properties, such as pigmentation and processing assistance Expandable fillers continue to be promising

Calcium carbonate is the most important filler, in terms of volume, but is relatively low in value In the plastics industry, it has mainly been used in PVC compounds, but 'engineered' grades (produced by adjusting particle size or geometry, and/or modifying the surface) are opening up a large potential market

in polyolefins, where the aim is not to extend the bulk of the compound but to offer positive properties, such as reducing cycle time and improving physical properties For example, very fine particles give marked increases in the

strength of films Stearic acid-coated grades give good mechanical properties and improved processing Suitable calcium carbonates can be used in part replacement of white pigment and to achieve high gloss (and to offset the reduction in gloss produced by replacement of lead stabilizers with calcium/zinc systems)

Other mineral fillers are coming into prominence, as users demand more and more of compounds Talc, mica, and wollastonite improve stiffness, heat stability, and expansion/shrinkage, and certain clays in sub-micrometre particle sizes (nano-particles) are currently the focus of research, to improve mechanical and also barrier properties, for very small percentage loadings

A new area of development is to incorporate the filler permanently into the polymer matrix, by use of coupling reactions This can increase impact strength and thermal properties of polyamides and modify the anisotropy of partially crystalline plastics, such as polyamides and polyesters In polypropylene, bonding with kaolin can also improve scratch resistance, which is a useful benefit for automobile interior applications Surface modification of fillers such

as silica, mica, and wollastonite allows these to penetrate markets that were formerly the province of reinforcements such as carbon black and glass fibre

2.7.2 Pigments

Regulations are still the key problem, as manufacturers strive to come up with effective pigments that also meet the heavy metal-free legislation High concentrations are also important, to save costs, but there is also fast-growing interest in pigments to produce special effects, such as pearlescence and edge-glow, and also strong interest in systems for laser marking

The main trend is still the development of alternatives to classic pigments based on heavy metals, such as cadmium While, ironically, voices are now being raised questioning whether cadmium pigments are really such a danger to the environment, new pigment systems are being commercialized that can effectively replace them and give brilliance that is comparable Colorants in liquid form are another area of study, to give processors the flexibility of changing colours within a production run, and pigments that give novel effects (such as metallics, pearlescents, and 'flip-flop' colour changes) are increasing in popularity

2.7.3 Plasticizers

While the plasticizers sector (which is almost totally bound up with PVC) has been dominated in recent years by controversy over the use of phthalates, there has been significant development in systems based on other materials, such as polymeric plasticizers Lubricants and processing aids also come into this classification, where the trend is towards adaptation to other plastics compounds, both standard and engineering plastics, and new systems that reduce or overcome migration, for use especially in food contact and medical/ healthcare applications

Figure 2.2 Many types of additives, such as stabilizers, are now supplied informs that are easier and safer to handle and use (Photograph: Akcros Chemicals)

2.1.4 Stabilizers

Stabilization (against both heat and light) is a main object of development, using new chemistry and fulfilling new market niches Stabilizers are increasingly needed in engineering plastics, to stabilize the compound during processing at higher temperatures and/or to provide stability for the application during continued exposure to elevated temperatures and/or outdoor conditions In this direction, the development of hindered amine light stabilizers (HALS) has been the most significant achievement, and there is also considerable research into the synergistic effects of employing two stabilizer systems in a compound

Replacement of heavy metal formulations is influencing all development, and the introduction of cadmium/zinc systems in a more effective form is significant Classically, stabilizers have used lead compounds and, on environmental grounds, manufacturers have volunteered to reduce levels to about 60% of today's usage by 2010 Calcium/zinc systems are now not included in the European Commission Ust of heavy-metal stabilizers, and these are seen as a key material for the future

2.7.5 Flame retardants

Flame retardants are probably the most researched group of additives today, to meet performance requirements under increasingly tight environmental conditions (which now also include behaviour during disposal of products by incineration) Recent development has been aimed especially at systems also

offering zero or very low emission of smoke and fumes when exposed to the heat

of combustion There is continuing controversy over the use of halogenated flame-retardant systems, and a general move towards non-halogenated/zero smoke types (especially among European legislators)

The critical end products involved are housings for consumer and office electronics equipment, wire and cable sheathing, and (as a result of recent tragedies) electrical equipment and rolling stock used for railways There is a move (also in Europe) to limit or prevent the use of flame retardants based on brominated systems, on the grounds of alleged difficulty in recycling, but this is being strongly opposed by the industry (and there is disagreement also among legislators)

A consequence of the need for investment in research and development will be the rationalization of the number of types on the market, and the emergence of a limited number of grades (possibly with fewer manufacturers)

2.2 Special Additives

In terms of functions, the emphasis is now on improvement of film processing, anti-static additives, 'special effect' pigments, multi-functional fillers, and stabilizing systems for engineering plastics Many of the new developments in individual additives are now being offered at the same time in safe, convenient technical masterbatch formulations

2.2.7 Antistatic and conductive additives

Conductive additives such as high-purity carbon blacks are commonly added to compounds where there is a potential hazard from electrostatic discharge There

is also extensive development of systems based on metal fibres, to give higher protection or shielding against electromechanical interference

2.2.2 Food contact and medical additives

Special purity requirements naturally have to be met for the many types of additives used for applications in contact with foodstuffs (such as packaging) and for medical products For many years, world authorities have operated a degree

of control over the use of additives in critical applications such as food contact and medical products A review of the relevant legislation is given in Chapter 23

In the USA, the relevant authority is the Food and Drug Administration (which also exerts considerable influence over products worldwide) In Europe, the European Union (EU) is the legislative authority In July 2000 it ratified an EU directive on food contact, listing additives in food-contact plastics that will require migration testing

Production of compounds for use in the medical sector has become an attractive (if very demanding) 'niche' for highly qualified specialists, able to operate globally, with strong financial resources

2.2.3 Clarifiers, nucleating agents, compatibilizers

Clarifiers and nucleating agents are making considerable progress, especially in polypropylene compounds, where they improve the clarity of the compound while assisting processability and set-up The advantages show themselves particularly in medical products and packaging Compatibilizers are increasingly used to aid the more effective use of other additives

2.3 Multi-functional Formulations

There is a marked trend towards multi-functional formulations (sometimes based on upgraded fillers or pigments) and single-pack formulations, such as for PVC The aim, all along, is to simplify operations at the compounding or processing level and to remove the need for precision weighing and metering of very small amounts Delivery of additives in a more convenient and safer form is also high on priority lists This obviously calls for significant research and development budgets and capital expenditure on more sophisticated production/ processing plants, which has the effect of raising the entry cost all the time for new producers A further cost pressure is the necessity to comply with legislation - often worldwide - and to be able to provide customers right down the line with documentation to prove compliance

2.4 Masterbatches

Most resins can be coloured by masterbatch or colour concentrate, or modified with an increasing range of special additive concentrates, at dosing rates of 0 5 -10%, but usually around 2% The use of self-colouring, however, is growing again, with the availability of more reliable and cheaper dosing equipment, with greatest growth being in gravimetric systems

Apart from the technical advantages, including reduction/rationalization of inventory, masterbatch has economic advantages, it is claimed Specialist Hanna notes that the cost of pre-colouration can generally be taken as about the same as that of compounding, which is about 0.2 7-0.3 kg"^ Masterbatch at 7.5 kg~^, dosed at 2% to colour a natural resin costing 0.90 kg~^ produces a cost of 0.13 kg~^ Adding the cost of the dosing equipment adds about 0.015 kg"^ to the total

Most major suppliers now offer masterbatches containing special additive formulations A typical range is that produced by Chrostiki It includes Mastertint black, white, colour, and special effect, Masterad slip, anti-static, and cleaning agent Filolen masterbatch offers calcium carbonate with very high softness and dispersion, giving very high whiteness and high purity Addition levels range from 2 to 5% for polypropylene woven tapes and big bags, to 5-20% for polyolefin injection mouldings, and 20-50% for biaxially oriented polypropylene film, thermoforming and pipe, sheet, and profiles

2.5 Dendritic Polymers

DSM has commercialized new dendritic (highly branched) polymers, under the name Hybrane Related to the original dendrimer, Astramol, these performance additives are described as 'hyperbranched' They do not require such a perfect structure as a dendrimer, but they generally retain many of the properties characteristic of these materials

They can assume a globular-like structure, leading to low melt viscosity because there is little entanglement between the molecules The globular molecules can also act as hosts for small *guest' molecules Interesting results can be obtained by combining different functional groups on the same polymer For example, one type of end-group can give compatibility with the matrix while another can provide surface-active effects or facilitate take-up of other molecules DSM sees potential applications in plastics as rheology modifiers and compatibilizers, and, in the wider field, in adhesives, toners, detergents, and cross-linkers Hybrane additives have also been studied for dyeing polypropylene fibres When used as compatibilizers, they can form links with other additives such as fillers, flame retardants, stabilizers, anti-statics, and fungicides

They can take up 20-2 5% of their own weight in water (compared with the maximum 10% of which linear polymers are capable) and can easily be modified

by the addition of other functional groups, including groups to regulate the migrating power of the additive in the compound during processing, possibly producing an enrichment of additive at the surface

CHAPTER 3

The World Market

Additives form a growing and valuable sector of speciality chemicals that has been selected by a number of manufacturers as a business sector It is difficult to give an accurate estimate of the world market for additives for polymers, because the figure depends very much on what is defined as an 'additive' There are as many different estimates as there are forecasters Most tend to limit the field to the so-called 'performance' additives - such as plasticizers, lubricants, stabilizers, flame retardants, and anti-statics - that confer a specific property or protection on the compound This excludes fillers and pigments, but increasingly significant portions of these are now also developed and marketed as 'performance' fillers or pigments, special carbon blacks, or titanium dioxides So

it is not surprising that there is some difference in estimates, arising to some extent from such overlaps

As well as regular market forces, other forces acting on the additives market include environmental and health issues, new technologies, inter-material competition, strategic repositioning for increased shareholder value, and customer-driven factors

3.1 World Consumption of Additives

While the volume of additives worldwide increased by 6% from 1996 to 1998, value actually fell, by 1%, due to the Asian crisis Trying to find some common ground between the best forecasts, it appears that the world additives market amounts to about 7.8 million tonnes, valued at about US$16 billion and is growing overall at about 3.5-4% per year Fillers account for an estimated 50%

by volume but in value they make up only 15% - and here Ues the stimulus for much current development

Asia Pacific is the largest global user of additives, accounting for some 35% of demand, by value North America and Europe are about equal, at 28 and 25%, respectively, while the rest of the world takes up the remaining 12%

There have been dramatic changes in the additives market The research agency Townsend considers that the world market for performance additives (flame retardants, stabilizers, anti-oxidants, modifiers, and lubricants) today