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Handbookof

PlasticTechnololV

Volume 1

Plastic Processing Operations

(Injection, Compression, Transfer & Blow Moulding)

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Contents at a Glance

Preface Conlenls in Derail

Chapter Chapter Chapter Chapter Chapter Chapler Chapter Chapter Chapter Chapter Chapter Chapter Chapter Chapter Chapter Chapter Chapter Chapter Chapter Chapter Chapter 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. I!. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21.

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Overview of Processing Operations Polymerisation Biodegradable Polymers Plastic Materials, Properties and Applications Mach~neries, M~terials and Parts Handling InJec~lO.n Moulding of PlastICS Specialised Injection Mouldmg Process Injection Moulding of Thermosets Extrusion PJ'Ocess Blow Moulding Compression and Transfer Moulding Thermoforming of Plastic Film and Sheet Rotational Moulding Calendering , Vinyl Dispersions , Powder Coatings Reinforced Plastics and Composites Cellular Plastics Radiation Processing Compounding Computer Aided Design, Manufacturing and Engineering (CAD, CAM, CAE) Chapter 22. Plant Control and Maintenance Chapter 23. Colouring of Plastics

.,

1-13

14-30 31-51 .

52-75

76-108 II

109-126 ',' \1 127-173· 174- 181 '\, 182-226 \ 227-250 \ I' 251-268 'j' 269-303

304-311 .

312-318

319-359

360-373

374-393

394-433

434-439

440-461

Ii

462-469

470-495

496-501

Refr!r~nces

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Index

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viii

Contents

Preface Contents ot a glance

v

viii

1-13

Blow moulding 8

Industrial blow moulding 10

Rotational moulding 10

Expanded polystyrene (EPS) 10

Reinforced plastics 10

Calendering 11

Structural foamed products 11

Tools for plastics 1l

Secondary tooling 12

Plastics tooling 13

14-30

Emulsion polymerisation 19

Weight, size and distribution of molecules 21

Polymer structure 22

Effect of time and temperature 24

Chemical composition 24

Copolymers 26

Other polymers 27

31-51

Environment 33

Substrate 33

Potential factors impacting polymer

degradation 34

Processing of PHBV 34

Production technology 34

Physical properties 34

Biodegradation 34

ix

Chapter 1. Overview of Processing Operations Introduction 1

Coordination of product requirements with

machine performance 2

Processirfg fundamentals 2

Moulding methods 4

Systems of moulding 4

Compression moulding 5

Transfer moulding 6

Injection moulding 7

Continuous extrusion 7

Chapter 2.Polymerisation Introduction 14

Polymer 14

Forming polymers 14

Polymerisation techniques 15

Bulk polymerisation 16

Solution polymerisation 17

Suspension polymerisation 19

Chapter 3. Biodegradable Polymers

Introduction 31

Basic methods of degradation 31

~ Biodegradation 31

Ki Photo-self destruction 32

Advantage of biodegradable polymers over

; photo-degradable polymers 32

Ii Key elements to biodegradation 32

Lorganisms 32

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Key biodegradation test met~odologies 35 Enzyme assays 35 Plate tests 35 Biological oxygen demand (BOD) 36 Radioactively labelled polymers 36 Respirometry 36 Laboratory scale simulated accelerated

environments 36

Natural environments 37

Biodegradation testing summary 37 Toxicity testing 37 Food contact 37 Biodegradation kinetics in marine and soil systems 38

Advantage 38

Materials and methods 38

Sample preparation 38

C~apter

Applications ofbiodegradable polymers 40 Application as packaging materials 40 Biodegradable polymer scaffolds to regenerate organs 40 Indigenous developments in biodegradable plastics 41 Degradable plastics 42 Polymers that resist high temperature 44 Applications 44 What is high temperature polymer? 45 General principles 45 Aromatic polyamide 46 Polyphenylene oxides 47· Polyimides 47 Organo-silicon polymers 48 Ladder polymers 49 Progress in India 5 J. 52-75

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4. Plastic Materials, Properties and Applications Polyamide-imide (PAl) 64 Polyarylates 64 Polycarbonates 64 Polyesters, thermoplastic 65 Polyetherimide (PEl) 66 Polyimide. thermoplastic 66 Polyketones 66 Polyphenylene ether (PPE) 67 Polyphenylene sulphide (PPS) 67 Sulphone polymers 68

Polysulphone (PSO) 68

Polyarylsulphone 68

Polyethersulphone (PES) 68

Thermoplastic elastomers (TPEs) 69 Alloys and blends 70 Thermosetting resins 70 Alkyds 7I Allylics 71 Bismaleimides (BMl) 71 Epoxies 72 Melamines 72 Phenolics 72 Polyesters 73 Polyimides 74 Silicones 74 Ureas 74 Polyurethanes 75

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Introduction 52 Thern~oplastic resins 53 Polyolefins 53

Polyethylenes 53

Polymethylpentene (PMP) 54

Polypropylene 55

Polybutylcne 56

Ethylene-vinyl alcohol (EVOH) 56

Styrene plastics 56 ASS resins 56 Polystyrene (PS) 57 Styrene-acrylonitrile (SAN) 58 Styrene-butadiene (SB) copolymers 58 Styrene-maleic anhydride (SMA) copolymers 58 Vinyl plastics 58 Polyvinyl chloride (PVC) 58 Chlorinated polyvinyl chloride (CPVC) 59 Polyvinylidene chlorine (PVDC) 59 Other thermoplastics 59 Acrylics 59 Acrylonitrile-based resins 60 Cellulosics 60 Engineering thermoplastics 61 Acetals 61 Fluoroplastics 61 Polyamides (nylons) 63

Contents xi

Chapter 5. Machineries, Materials and Parts Handling Introduction 76

Injection moulding machine 7(,

Co-injection moulding 78

Process 78

Equipment 79

Reaction injection moulding (RIM) 79

Low pressure~ 79

Low temperature 79

Liquid intermediates 80

Equipment 80

Material conditioning system 80

Metering system 80

Mixing head 80

Mould carrier 81

Tooling 81

Blow moulding machines 81

Stretch blow moulding 83

Proetss 83

Multilayer blow moulding 114

Rotational moulding machines 114

Recent developments 85

Process controls 85

Alternative raw materials 86

Newapplications 86

Extrusion equipment 87

Twin screw pipe plants 88

Thermoforming machines 89

Polyurethane machinely (including rim) 90

Pultrusion and pulfonning machine 91

Equipment and process 91

MachinelY for casting of film 93

Charlter 6. Injection Moulding of Plastics Introduction 109

Injection moulding process 110

Machine ratings 114

Influence of material properties on the

moulding 115

Nozzle 116

Runners and gates 116

Mould 118

Product design for injection moulding 120

76-108

7

Equipment 93

Slitting station 94

Pull out 94

Trim removal and recycling system 94

Polymers 94

PTFE processing equipments 94

Processing of suspension polymers 95

Compression moulding 95

Equipment 95

Mould 95

Sintering 96

Free sintering 96

Cooling 96

Product range and application 96

Isostatic compression moulding 97

Applications 97

Automatic moulding 97

RAM extrusion 98

Processing of emulsion polymers 99

Equipment 99

Unsintered tape and profile 100

Dispersion coatings 100

Machining and fubrication 100

Fabrication 103

Material and pal1s handling 103

Vacuum loaders 104

Positive-displacement vacuum loaders 104

Colouring loaders 105

On-the machine blenders 106

Bulk vacuum flow systems 107

Plastics material drying 108

109-126

Coloured moulding 121

Moulding problems 121

Finishing and regrinding 122

Purging 122

Process control 123

Computer integrated injection moulding 125

Microprocessor control systems 125

Computerised process simulation ofinjection

moulding 126

xii

Contents

Chapter 7. Specialised Injection Moulding Process Introduction 127

Co-injection moulding 127

Two-colour moulding /29

Gas injection moulding (GIM) 129

Advantages and disadvantages 130

Advantages 130

Basic processes and procedures /3/

Disadvantages 131

Processes 132

Procedures 133'

Moulding aspects 134

Shrinkage 135

Multi-live moulding /36

Counterflow moulding 136

Oscillatory moulding for optical disks 138

Reaction injection moulding 139

Mould 142

Process controls 143

Liquid inje'ction moulding 143

Structural foam moulding (SFM) 144

Performance 144

Plastic materials 145

Characteristics of foam 145

Design analysis 146

Blowing agents 149

Methods of processing structural foam (SF)

with chemical blowing agents (CBA) 150

Low-pressure foam /50

High-pressure foam 151

Processing SF with gas blowing agent 151

Startup for moulding 152

Tandem processing systems 153

Tandem moulding machines 153

Operational sequence 154

Coining 154

Injection blow moulding (IBM) 154

Injection mouiding with rotation 156

Chapter 8. Injection Moulding of Thermosets Introduction 174

Process operations 175

Process and design considerations 176

Materials /76

Process effects on design 177

Injection-compression moulding 178

Part-design considerations 178

Cold runner moulding 179

Injection moulding reinforced

polyesters /79

Injection moulding presses 180

Temperature control 181

127-173

Dip injection blow moulding 158

Materials 158

Metal injection moulding (MIM) 159

Ceramic injection moulding /60

Fusible and soluble core moulding 161

Vacuum moulding 161

Troubleshooting in injection moulding /62

Injection moulding problems 162

Problem of short shots 162

Problem of flashing 163

Problem of sink marks 163

Problems of bubbles and voids /63

Problem of brittleness of component 164

Problem of discoloration 164

Problem of silver streaks 165

Problem of nozzle drooling and foaming 165

Problem of scorching 165

Problem of sprue sticking 166

Problem of surface lamination /66

Problem of parts sticking to the mould /66

Problem of surface waviness (pits, oraoge

peel, wrinkles) 167

Problem of fractures and cracks 167

Problem of warping 168

Problem of weld lines 168

Problem ofdimensional variation 168

Problem ofjetting 169

Problem of gate smear /69

Technological solutions for total quality in injection moulding of plastics /69

Machine 170

Mould /70

Material 170

Man 170

Quality related problems 171

Problems of moulding /71

Perfect mouldability 172

174-181

Contents

xiii

Chapter 9. Extrusion Processes Introduction 182

Extrusion instabilities or variabilities 186

Plastics handling 187

Multiple screw extruders 189

Single screw extruders 191

Mixing and melting 192

Venting 193

Screen packs 194

Energy consumption 196

Gear pumps 197

Dies 198

Basics of flow 200

Special dies 201

Materials of construction 201

Maintenance 202

Chapter 10. Blow Moulding

Introductipn 227

Extrusion blow moulding (EBM) 229

Melt 232

Parison thickness control 233

Parison swell 235

Pinch-off 236

BJowingthe parison 237

Coextrusion 202 Tie-layers 204 Orientation 204 Processing lines 207 Blown film 207 Flat film 210 Sheet 211 Coatings 214 Wire coating 214 Coating wood profiles 215 Coating films/foils 215 Controls 216 Downstream controls 218 Extruder operation 220 Troubleshooting 222 , Cooling 239 Clamping 239 Shrinkage 240 Mould construction 244 Plastics 245 Controls 247 Troubleshooting 248

182-226

227-250

Chapter ll. Compression and Transfer Moulding

Introduction 251

Compression moulding 252

Technique and materials 252

Thermosetting materials 252

Thermoplastics 253

Mouldingofphenol-formaldehyde

compounds 253

Moulding of urea-formaldehyde and melamine

formaldehyde compounds 255

Moulding ofgeneral-purpose polyester moulding

compounds 255

Moulding for alkyd materials 256

Moulding of thermoplastic materials 256

Moulding of fluorocarbons 256

Cold moulding 257

Advantages and limitations of compression

moulds 257

Advantages of compression moulding 257

251-268

Limitations of compression moulding 258 Procedure for compression moulding 259 Important variables in the compression moulding of thermosetting materials 259 Thermoset compounds 260 Fillers/reinforcements 261 Types of resins 261 Preheating 262 Outgassing 262 Postcuring 262 Compression moulding machines (CMM) 263 Transfer moulding (TM) 263 Moulding 264 Venting 265 Flash 265 Pressure 266 Cavity plating 266 Shrinkage 267

xiv

Contents

Thermoplastics 267

Mould construction 267

Runners-cold and hot 267

Design analysis 268

269-303

Chapter 12. Thermoforming of Plastic Film and Sheet Introduction 269

Methods of thermoforming 270

Vacuum forming into a female mould 270

Pressure forming into female cavity 272

Free forming 273

Plug-assist forming 273

Drape forming 273

Matched mould forming 275

Trapped sheet 276

Plug-and-ring forming 277

Ridge forming 278

Slip forming 278

Snap-back forming 280

Billow-up prestretch techniques 280

Bill~w,up plug assist (or reverse draw with

'plug assist) 283

Billow-up vacuum snap-back 283

Dual sheet forming 283

Tilermoforming machines 286

Single-stage. sheet-fed machine 286

MUltiple-stage. sheet-fed machines 286

In-line, sheet-fed machines 289

Continuous roll-fed machines 289

Packaging machines 289

Matedals 289

Chapter 13. Rotational Moulding Introduction 304

Advantages of rotational moulding 306

Steps in rotational moulding 306

Machinery 307

Batch-type machines 307

Carousel-type machines 307

I

Characteristics and properties of thermoplastic

sheets 290

Hot elongation or hot strength 291

Temperature range for forming 291

Thermoforming processing temperatures 291

Heating 293

Temperature control 293

Vacuumlair pressure 294

Tooling 294

Trimming 295

Problems of shrinkage 297

Trimming in tbe mould 297

Control 297

Manual-control equipment 297

Automation 297

Control systems 298

Microprocessor control 298

PLC (Programmable logic controller) 298

Electro-mechanical control 299

Thermoforming of coextruded structures and

otber special materials 299

Cooling re<juirements of the thermoforming

process 300

Substrate thermoforming 300

Troubleshooting 302

304-311

Independent-ann-type machines 308

Straight-line machines 308

Jacketed-mould machines 308

Moulds 308

Materials 309

Part design 310

312-318

Calender 315

Take-off stripper section 317

Em bosser 318

Winder 318

Chapter 14. Calendering Introduction 312

Blending 313

Scrap and cold trim 313

Mills and strainers 314

'

Contents

xv

hapter .IS. Vinyl Dispersions

319-359

Spread coating metal substrates 347

Miscellaneous coating applications 348

Moulding 349

Dip coating and dip moulding 349

Hot dipping process 350

Cold dipping process 351

Rotational moulding 351

Moulds 352

Heating systems 353

Machinery setups 354

Formulating considerations 355

Slush moulding 355

Moulds 356

Formulating considerations 356

Cavity, in-place, and low-pressure moulding 357

Cavity moulding 357

In-place moulding 357

Low-pressure moulding 357

Specialised processes 358

Strand coating 358

Spray coating 359

Extrusion 359

360-373

Polyethylene 367

Polypropylene 368

Cellulose acetate butyrate (CAB) 368

Nylon 368

Thermoplastic polyester 368

Thermosetting types 369

Epoxy 369

Epoxy polyester hybrids 369

Polyester/polyurethane 370

Glycidyl polyester 370

Acrylics 371

Application line 371

Economics 372

374-393

Fillers and additives 376

Reinforcements 376

Preforms, compounds, and prepregs 378

Processes 380

troduction 319

-303' Resins 320

Rheology 321

astic Fusion 322

Formulating vinyl plastisols 323

Dispersion and blending resins 325

Plasticisers 327

Stabilisation 330

291

Thinners 331

Fillers 331

Pigment 331

Speciality ingredients 332

Plastisol preparation 333

PropertY determination 334

pread coating processes and applications 338

Spread coating 339

Knife coating 339

Roll coating 341

Fusion'M3

Web handling and finishing 343

Fabric coating 344

Coating paper and non-woven material 346 ,

8

Film castiJ'g 347

hapter 16. Powder Coatings Introduction 360

Manufacturing methods 361

Dry blend 361

Melt mix 362

Solution 363

Application methods 364

, Fluidised bed 364

Electrostatic spraying 365

Friction static spraying 366

Electrostatic fluidised bed 366

Types of powder coatings 366

Thermoplastic types 366

Polyvinyl chloride (PVC) 366

hapter 17. Reinforced Plastics and Composites ntroduction 374

'enninology 374

hermosetting plastics 375

hermoplastics 376

311

318

xvi

Contents

Open (or contact) moulding 380

Compression moulding 382

Injection moulding 383

Reactive and resin transfer moulding 38-1

Chapter 18. Cellular Plastics Introduction 394 Chemical blowing agents 395 Choice of blowing gas 395 Polyurethane foams 396 Chemistry 396 Polyols and polyisocyanates 396 Modifiers and additives 397 One-shots and prepolymers 397 Rigid polyurethane and polyisocyanurate foam 397

Processing rigid polyurethane foams 398

Flexible polyurethane foams 399

Processing flexible polyurethanes 399

SljlIJstock foam process 399

Flexible foam mOUlding process 399

Semi-rigid foams 400

Reaction injcction moulding (RIM) 400 , Reaction injection moulding (RIM) process 402 Materials for reaction injection moulding 402 Equipment for reaction injection moulding 403 Mould for reaction injection moulding (RIM) 404

Mould gating ,405

Part design 405

Applications of reaction injection moulding

(RIM) 406 Polyurethane processing equipment 406 Equipment for spray applications 406 Equipment for pour-in-place applications 407 Equipment for moulding applications 408 Equipment for the production of slab foam 408 Equipment for cast elastomer applications 409 Accessory items 409 Heat exchangers 4/0

Heating and cooling units 410

Instrumentation 4/0

Other accessories 4/1

Thermoplastic structural foalris 4/1 Properties of structural foams 4/1 Combustibility 4/2

Continuous processes 386 Other moulding processes 388 Features and benefits 389 Markets and applications 39/

,. 394-433 ' Making structural foams J/2 Process details -1/3 Low-pressurc/nitrogen 4/3 Low-pressure/chemical blowing agent 4/3 High-pressure systems 4/4 Gas counterpressure 4/5 Designing with structural foam 4/6 Mechanical properties 4/6 Tensile strength 4/6 Compressive strength 4/7 Stiffness-to-weight 4/7 Flexural properties 4/7 Coefticient of expansion 4/7 Impact 4/7 Load-bearing environments 4/7 Extreme temperature environments -1/8 Chemical environments -1/8 Finishing -1/8

Part preparation -1/8

Alternative surface finishes 4/9

EMI shielding 4/9

Foam extrusion 4/9 Gas-assisted injection moulding 420 General design considerations 420 Application areas 420 Polystyrene' foams 420 Extruded polystyrene foam 42/ Moulded bead polystyrene foam 42/ Bead expansion 42/ Moulding shaped parts 422 Block moulding 422 Expanded polystyrene sheet 422 Polystyrene foam properties -123 Applications for extruded polystyrene foam -123 Applications for polystyrene sheet 423 Applications for bead polystyrene foam 424 Applications for loose-fill polystyrene foam 42-1 Cellular polyethylene 42-1

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Contents

xvii

Production 424

Properties 425

Applications 426

Low density polyethylene foams 426

Compression characteristics 428

Compression deflection 428

Compressive crepe 428

Compression set recovery 429

Tensile and tear strength 429

Dynamic cushioning 429

Water properties 429

Chapter 19. Radiation Processing Introduction 434

Ionising radiation 434

Crosslinking thermoplastics for wire and

cable 434

Crosslinking thermoplastics for packaging

Thermal properties 429

Thermal conductivity 429

Thermal stability 430

Electrical properties 430

Fabrication 430

Bonding 430

PVC foams 431

lonomer foams 431

Epoxy foams 432

Phenolic foams 432

Silicone foams 432

, ................................·

434-439

Graft copolymers 436

Radiation-induced curing of coatings 437

Irradiated concrete-plastic composites 437

Non-ionising radiation 438

Ultraviolet radiation 438

Infrared radiation 438

Inductive (magnetic) energy 439

Dielectric energy 439

Microwave energy 439

440-461

Blowing agents 450

Lubricants 451 .

Methods of compounding 452

Intensive dry mixers 452

Internal intensive batch mixer 452

Continuous mixer 453

Two-roll mills and pelletisers 454

Underwater pelletiser 455

Single-screw extruders 455

Compounder-extruder 457

Twin-screw extruder 458

Compounding lines 459

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Crosslinked foamed resins 436

Techniques for producing cross-linking

thermoplastic foams 436

Chapter 20. Compounding Introduction 440

Mixingtheory 441

Limitations ofmixing theory 442

Mixingevaluation 442

Fillers 444

Plasticisers 445

Colorants 446

Heat stabilisers 448

Antioxidants 448

Ultraviolet light absorbers 449

Antistatic agents 450

Flame retardants 450

Chapter 21. Computer Aided Design, Manufacturing and Engineering

(CAD, CAM, CAE) Introduction 462 Computer aided design (CAD) 463 Graphics programming 464 Computer aided manufacturing (CAM) 464

462-469

Computer aided engineering (CAE) 465

Mould design 469

Product design with CAD/CAM/CAE' 469

xviii

Contents

Chapter 22. Plant Control and Maintenance Introduction 470

Plant control 470

Controls and instrumentation 477

Machine control 477

Timing/sequencing 478

Process control 478

Extrusion 478

Process condition sensors 481

Camera comparator techniques 481

On-line quality control 482

Ultrasonic measuring 483

Film thickness measurement 483

Radiation systems 483

Chapter 23. Colouring of Plastics Introduction 496

Methods of manufacture 496

AdvjJntages in processing 496

Types of master batches 497

White masterbatches 497

Black masterbatches 497

Colour masterbatches 498

Additive masterbatches 498

Antitibrilliation masterbatches 499

470-495:

~:~!

~ Pressure within a melt 483

Preventive maintenance 484

~ Equipment improvements 485

Technical cost modeling 485 I:~!

Plastics growth 486

Auxiliary equipment and secondary operations 48711

Material handling 487

Energy conservation 489

I~I Parts handling 489

Clean pellets/plant 490

Drying plastics 491

Feeder/blender 494 Granulating 495

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496-501

UV light stabiliseI' masterbatch 499

Antioxidant masterbatch 499

Polymer processing aid masterbatches 499

Antiblocking agent masterbatches 500

Slip additive masterbatches 500

Antistatic masterbatches 500

Flame retardant masterbatches 501

Nucleating agent masterbatches 501

Cling additive masterbatches 501

References Index

503-504

505-510

Information

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