The Coloration of Wool and Other Keratin Fibres

List of Contributors xiii

Society of Dyers and Colourists xv

Preface xvii

1 The Structure of Wool 1 John A. Rippon

1.1 Introduction 1

1.2 Composition of Wool 2

1.3 Chemical Structure of Wool 5

1.3.1 General Chemical Structure of Proteins 5

1.3.2 Amino Acid Composition of Wool 6

1.3.3 Arrangement of Amino Acids in Wool 8

1.3.4 The Structure of Wool Proteins 11

1.3.5 Wool Lipids 13

1.4 Morphological Structure of Wool 14

1.4.1 The Cuticle and the Fibre Surface 16

1.4.2 The Cortex 23

1.4.3 The Cell Membrane Complex 27

1.5 Chemical Reactivity of Wool 32

1.6 Damage in Wool Dyeing 32

1.6.1 Nonkeratinous Proteins and Damage in Dyeing 33

1.6.2 Influence of Dyebath pH on Fibre Damage 34

1.7 Conclusion 35

References 35

2 The Chemical and Physical Basis for Wool Dyeing 43 John A. Rippon

2.1 Introduction 43

2.2 The Chemical Basis for Wool Dyeing 43

2.2.1 The Wool-Water System 44

2.2.2 The Amphoteric Nature of Wool and Dyeing Behaviour 44

2.2.3 Classical Theories of Wool Dyeing 46

2.2.4 Modern Theories of Wool Dyeing 49

2.3 Standard Affinity and Heat of Dyeing 50

2.4 Classification of Dyes Used for Wool 52

2.5 Dye Aggregation 55

2.6 The Physical Basis for Wool Dyeing: The Role of Fibre Structure 60

2.6.1 Diffusion of Dyes 60

2.6.2 Pathways of Dye Diffusion into Wool 61

2.7 Effect of Chemical Modifications on Dyeing 66

2.7.1 Chlorination 66

2.7.2 Plasma Treatment 67

2.7.3 Differential Dyeing 68

2.8 Conclusion 68

References 69

3 The Role of Auxiliaries in the Dyeing of Wool and other Keratin Fibres 75 Arthur C. Welham

3.1 Introduction 75

3.2 Surface Activity of Wool-Dyeing Auxiliaries 76

3.2.1 Anionic Auxiliaries 76

3.2.2 Cationic Auxiliaries 77

3.2.3 Ethoxylated Nonionic and Cationic Auxiliaries 78

3.2.4 Amphoteric Auxiliaries 80

3.2.5 Other Auxiliaries 81

3.3 Brightening Agents 81

3.4 Levelling Agents 82

3.4.1 Material Faults 83

3.4.2 Dyeing and Processing Faults 83

3.4.3 Testing the Action of Levelling Agents 85

3.4.4 Product Selection 86

3.4.5 Coverage of Skittery or Tippy-Dyeing Wool 86

3.5 Restraining and Reserving Agents in Wool Blend Dyeing 88

3.6 Antiprecipitants 89

3.7 Wool Protective Agents 89

3.8 Low-Temperature Dyeing 90

3.9 Correction of Faulty Dyeings 92

3.10 Aftertreatments to Improve Wet Fastness 93

3.11 Effluent Control in Chrome Dyeing 94

3.12 Antifrosting Agents 95

3.13 Antisetting Agents 95

3.14 Sequestering Agents 96

3.15 Conclusions 96

References 97

4 Ancillary Processes in Wool Dyeing 99 David M. Lewis

4.1 Introduction 99

4.2 Wool Scouring 99

4.3 Wool Carbonising 100

4.4 Shrink-Resist Treatments 102

4.4.1 Top Shrink-Resist Processes 102

4.4.2 Garment Shrink-Resist Treatments 105

4.4.3 Fabric Shrink-Resist Treatments 106

4.4.4 Miscellaneous Developments 107

4.4.5 Colour-Fastness Requirements for Machine-Washable Wool 108

4.5 Insect-Resist Treatments 108

4.5.1 Insect Pests 108

4.5.2 Insect-Resist Agents 109

4.5.3 Application Methods for IR Agents 113

4.6 Flame-Retardant Treatments 115

4.7 Antisetting Agents 116

4.7.1 The Role of Oxidants in Preventing Setting in Dyeing 118

4.7.2 The Role of Electrophilic Reagents in Controlling Setting in Dyeing 119

4.8 Fibre Arylating Agents (FAA) 120

References 126

5 Bleaching and Whitening of Wool: Photostability of Whites 131 Keith R. Millington

5.1 Introduction 131

5.2 Wool Colour 132

5.2.1 Measuring Wool Colour 132

5.2.2 Improving Wool Colour by Selection 134

5.2.3 Improving Colour in the Scour 134

5.2.4 Nonscourable Yellowing 135

5.2.5 Wool Colour Compared with Cotton and Synthetics 135

5.3 Wool Bleaching 138

5.3.1 Oxidative Bleaching 138

5.3.2 Reductive Bleaching 139

5.3.3 Double (or Full) Bleaching 140

5.3.4 Bleaching of Pigmented Wools 140

5.3.5 Bleaching in the Dyebath 140

5.3.6 Biobleaching of Wool Using Enzymes 142

5.3.7 Activated Peroxide Bleaching 143

5.3.8 Catalytic Peroxide Bleaching 144

5.3.9 Novel Bleaching Methods for Wool 144

5.4 Fluorescent Whitening of Wool 144

5.5 Photostability of Wool 145

5.5.1 Mechanism of Wool Photoyellowing 148

5.5.2 Mechanism of Photoyellowing of Fluorescent Whitened Wool 149

5.5.3 Methods for Improving Photostability 151

References 153

6 Wool-dyeing Machinery 157 Jamie A. Hawkes and Paul Hamilton

6.1 Introduction 157

6.2 Top Dyeing 158

6.2.1 Longclose (UK) Large Bump Tops 160

6.2.2 Obem Big Form 161

6.2.3 Vigoreux Printing 161

6.3 Loose Stock Dyeing 162

6.3.1 Continuous Dyeing of Loose Stock 165

6.4 Hank-Dyeing Yarn 166

6.4.1 Carpet Yarn 166

6.4.2 Hand-Knitting and Machine-Knitting Yarn 167

6.4.3 Robotic Handling 169

6.4.4 Space Dyeing of Yarn 169

6.5 Yarn Package Dyeing 171

6.5.1 Package Preparation 172

6.5.2 Machinery 175

6.6 Piece Dyeing 178

6.6.1 Jet and Overflow Dyeing 178

6.6.2 Beam Dyeing 179

6.7 Garment Dyeing 179

6.8 Carpet Piece Dyeing 182

6.9 Drying 183

6.9.1 Mechanical Moisture Removal 183

6.9.2 Thermal Moisture Removal 184

6.10 Dyehouse Automation 186

6.10.1 Dyehouse Control Systems 186

6.10.2 Factory Management Systems 188

6.10.3 Process Control 188

6.10.4 Effluent Control Systems 190

6.10.5 Colour Measurement 191

6.11 Laboratory Dyeing 192

6.11.1 Tops, Loose Stock, Hanks and Package Yarn 193

6.11.2 Piece Dyeing 198

6.11.3 Garment Dyeing 201

6.11.4 Laboratory Machine Control Systems 202

References 203

7 Dyeing Wool with Acid and Mordant Dyes 205 Peter A. Duffield

7.1 Introduction 205

7.2 Acid Dyes 208

7.2.1 Acid Dye Subclassification 208

7.2.2 Optimised Dye Ranges 213

7.3 Natural Dyes 213

7.4 Mordant Dyes 214

7.4.1 Chrome Dyeing Processes 216

7.4.2 Theoretical Aspects 219

7.4.3 Low-Chrome Dyeing 223

7.5 Specific Dyeing Methods 226

References 227

8 Dyeing Wool with Metal-complex Dyes 229 Stephen M. Burkinshaw

8.1 Introduction 229

8.2 Dye Structure 230

8.2.1 Electronic Structure 232

8.2.2 Colour and Light Fastness 235

8.2.3 Stereochemistry and Isomerism 236

8.2.4 1 : 1 Metal-Complex Dyes 237

8.2.5 1 : 2 Metal-Complex Dyes 239

8.3 Dye Application 242

8.3.1 1 : 1 Metal-Complex Dyes 242

8.3.2 1 : 2 Metal-Complex Dyes 246

8.4 Environmental Aspects 248

References 248

9 Dyeing Wool with Reactive Dyes 251 David M. Lewis

9.1 Introduction 251

9.2 Commercial Reactive Dyes for Wool 252

9.3 The Chemistry of Reactive Dyes 253

9.3.1 Nucleophilic Substitution Reactions 253

9.3.2 Michael Addition Reaction 253

9.3.3 Specific Reactive Dyes for Wool 254

9.4 Application Procedures 260

9.4.1 Auxiliary Agents 260

9.4.2 Dyeing Processes Used with Reactive Dyes 261

9.4.3 Effect of Reactive Dyes on Fibre Properties 276

9.5 Novel Reactive Dye Systems for Wool 281

9.5.1 Maleinimides 281

9.5.2 Isocyanate and Isothiocyanate Bisulphite Adducts 281

9.5.3 Carboxymethyl Carbodithioate Dyes 282

9.5.4 Trifunctional Reactive Dyes Prepared from Bis-(chloroethyl-sulphonylethyl)amine [P-3] Reaction with a DCT Dye 282

9.5.5 Crosslinking Agents to Covalently Fix Acid Dyes to Wool 283

9.6 Identification of the Reaction Sites in the Fibre 285

9.7 Conclusions 287

References 287

10 Dyeing Wool Blends 291 David M. Lewis

10.1 Introduction 291

10.2 Wool/Cotton 293

10.2.1 Dyeing of Cotton 293

10.2.2 Exhaustion Dyeing of Wool/Cotton Blends 296

10.2.3 Pad Dyeing of Wool/Cotton Blends 300

10.2.4 Wool Damage during Dyeing 301

10.3 Amination of Cellulosic Fibres 303

10.4 Wool/Silk 305

10.4.1 Dyeing of Silk 306

10.4.2 Dyeing of Wool/Silk Blends 308

10.5 Wool/Nylon 310

10.5.1 Dyeing of Nylon 310

10.5.2 Dyeing of Wool/Nylon Blends 319

10.6 Wool/Polyester 323

10.6.1 Dyeing of Polyester 323

10.6.2 Dyeing of Wool/Polyester Blends 333

10.7 Wool/Acrylic 341

10.7.1 Dyeing of Acrylic Fibres 342

10.7.2 Dyeing of Wool/Acrylic Blends 348

10.8 Conclusions 351

References 352

11 The Coloration of Human Hair 357 Robert M. Christie and Olivier J.X. Morel

11.1 Introduction 357

11.2 Structure and Morphology of Human Hair 359

11.3 Natural Colour of Hair 360

11.4 Physical Chemistry of Hair Dyeing 364

11.5 Toxicology of Hair Dyes 365

11.6 Oxidative Hair Coloration 366

11.7 Alternative Approaches to Permanent Hair Dyeing 369

11.8 Nonoxidative Hair Dyeing 375

11.9 Conclusion 386

References 387

12 Wool Printing 393 Peter J. Broadbent and Muriel L.A. Rigout

12.1 Introduction 393

12.2 Preparation for Printing 394

12.2.1 Oxidative Processes 394

12.2.2 Polymer Treatments 396

12.2.3 Plasma Treatments 397

12.2.4 Other Methods of Preparation for Printing 398

12.3 Direct Printing 399

12.3.1 Machinery 399

12.3.2 Dye Selection and Print Recipes 399

12.3.3 Steaming 402

12.3.4 Washing and Aftertreatment 404

12.4 Discharge Printing 405

12.4.1 Ground Shades 405

12.4.2 Discharge Agents 405

12.4.3 Illuminating Dyes 407

12.4.4 Printing and Fixation 407

12.5 Resist Printing 408

12.5.1 Chemical Resist Processes 409

12.5.2 Mechanical/Chemical Resist Processes 411

12.5.3 Reactive-Under-Reactive Resist 412

12.6 Digital Printing 412

12.6.1 Machinery 413

12.6.2 Ink Formulation 413

12.6.3 Fabric Pretreatment 415

12.6.4 Fixation 417

12.6.5 Wash-Off 417

12.7 Wool Blends 418

12.7.1 Wool/Polyester 419

12.7.2 Wool/Cotton 419

12.7.3 Wool/Acrylic 420

12.8 Cold Print Batch 420

12.9 Transfer Printing 421

12.9.1 Wet or 'Migration' Transfer Printing 421

12.9.2 Sublimation Transfer Printing 422

12.9.3 Benzoylated Wool 424

12.10 Novel Effects 425

12.10.1 Burn-Out (devorée) Printing 425

12.10.2 Sculptured Effects 425

References 426 Index 431