The Coloration of Wool and Other Keratin Fibres

Keratin fibres, particularly wool fibres, constitute an important natural raw material in textiles due to their comfort and thermal proprieties. Wool coloration demands an understanding of the complex nature of the interplay between wool fibre chemistry, morphology and the coloration processes.

The Coloration of Wool and other Keratin Fibres is a comprehensive treatment, written by leading international experts, of the chemistry and chemical processes involved in wool dyeing, printing, preparation and finishing.

The book covers: 

• the chemical and physical structure of wool keratin fibres, detailing their complex heterogeneity and the subtle links between fibre structure and dyeability
• the coloration of fabrics containing wool, including a variety of wool blends such as wool/silk, wool/polyester and wool/cotton, and luxury keratin fibres such as mohair, cashmere and camel
• the chemistry of the various types of dyes utilised in wool dyeing and in-depth discussions on the physical properties to optimise these processes
• practical application of dyes to wool in all its forms, loose stock, combed tops, yarns and piece goods, is covered in the chapter on wool dyeing machinery
• two chapters, one on bleaching and whitening and one on dyeing human hair, provide a valuable extension to the topic of cosmetic chemistry

The Coloration of Wool and other Keratin Fibres is essential reading for professionals world-wide working in companies involved in the dyeing and printing of wool, wool blends and other keratin fibres and also for the producers of dyes and auxiliary dyeing agents. It is a valuable resource for teachers and students of universities and technical institutes, as well as for researchers who are focusing their investigations on wool, wool blends, human hair or dyes and auxiliaries.


Published in partnership with the Society of Dyers and Colourists (SDC).
Find out more at www.wiley.com/go/sdc

Editors
David M. Lewis Department of Colour Science, University of Leeds, UK

John A. Rippon CSIRO Materials Science and Engineering, Australia

Society of Dyers and Colourists xvii

Preface xix

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

1.3.3.1 Covalent Crosslinks 10

1.3.3.2 Noncovalent Bonds (Interactions) 10

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

1.4.1.1 The Epicuticle and the Allw¨orden Reaction 19

1.4.1.2 The Epicuticle and the Hydrophobic Surface of Wool 21

1.4.1.3 The Exocuticle 22

1.4.1.4 The Endocuticle 22

1.4.2 The Cortex 23

1.4.2.1 Intermediate Filament/Matrix Structure 24

1.4.2.2 Macrofibrils, Nuclear Remnants and Intermacrofibrillar

Material 25

1.4.2.3 Ortho/Para Segmentation of the Cortex 26

1.4.3 The Cell Membrane Complex 27

1.4.3.1 Intercellular Cement 29

1.4.3.2 Lipid Component of the Cell Membrane Complex 29

1.4.3.3 Resistant Membranes 29

1.4.3.4 Amount of Cell Membrane Complex in Wool 30

1.4.3.5 Differences Between Cell Membrane Complexes in

Cuticle and Cortex 31

1.4.3.6 The Cell Membrane Complex and Fabric Properties 31

of Contributors xv

Society of Dyers and Colourists xvii

Preface xix

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

1.3.3.1 Covalent Crosslinks 10

1.3.3.2 Noncovalent Bonds (Interactions) 10

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

1.4.1.1 The Epicuticle and the Allw¨orden Reaction 19

1.4.1.2 The Epicuticle and the Hydrophobic Surface of Wool 21

1.4.1.3 The Exocuticle 22

1.4.1.4 The Endocuticle 22

1.4.2 The Cortex 23

1.4.2.1 Intermediate Filament/Matrix Structure 24

1.4.2.2 Macrofibrils, Nuclear Remnants and Intermacrofibrillar

Material 25

1.4.2.3 Ortho/Para Segmentation of the Cortex 26

1.4.3 The Cell Membrane Complex 27

1.4.3.1 Intercellular Cement 29

1.4.3.2 Lipid Component of the Cell Membrane Complex 29

1.4.3.3 Resistant Membranes 29

1.4.3.4 Amount of Cell Membrane Complex in Wool 30

1.4.3.5 Differences Between Cell Membrane Complexes in

Cuticle and Cortex 31

1.4.3.6 The Cell Membrane Complex and Fabric Properties 31

3.4.2.1 Method 1 84

3.4.2.2 Method 2 84

3.4.2.3 Method 3 84

3.4.2.4 Method 4 85

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

3.10.1 Effluent Control in Chrome Dyeing 94

3.11 Antifrosting Agents 95

3.12 Antisetting Agents 95

3.13 Sequestering Agents 96

3.14 Conclusion 96

References 97

4 Ancillary Processes inWool Dyeing 99

D.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

4.4.2.1 Chlorine–Resin Processes 105

4.4.2.2 Polymer-Only Systems 106

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

4.5.2.1 Mitin FF High Conc. (CGY) 111

4.5.2.2 Eulan U33, Eulan WA New (BAY) 111

4.5.2.3 Mitin AL (CGY) 112

4.5.3 Application Methods for IR Agents 113

4.5.3.1 Application During Dyeing 113

4.5.3.2 Application During Scouring 113

4.5.3.3 Application by Addition to Spinning Lubricants 114

4.5.3.4 The Current and Future Status of Wool Moth-Proofing 114

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 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

6.11.1.1 Moving Fabric and Moving Liquor 193

6.11.1.2 Stationary Beaker and Moving Liquor 196

6.11.1.3 Stationary Beaker and Moving Liquor 196

6.11.1.4 Stationary Liquor and Moving Fabric 198

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

P.A. Duffield

7.1 Introduction 205

7.2 Acid Dyes 208

7.2.1 Acid Dye Subclassification 208

7.2.1.1 Level-Dyeing or Equalising Acid Dyes 209

7.2.1.2 Fast Acid or Half-Milling Dyes 211

7.2.1.3 Milling and Super-Milling Dyes 212

7.2.2 Optimised Dye Ranges 213

7.3 Natural Dyes 213

7.4 Mordant Dyes 214

7.4.1 Chrome Dyeing Processes 216

7.4.1.1 Prechrome Dyeing 217

7.4.1.2 Metachrome Dyeing 217

7.4.1.3 Afterchrome Dyeing 218

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

8.2.5.1 Weakly Polar 1 : 2 Dyes 239

8.2.5.2 Strongly Polar 1 : 2 Dyes 240

8.3 Dye Application 242

8.3.1 1 : 1 Metal-Complex Dyes 242

8.3.1.1 Dye–Fibre Interaction 244

8.3.2 1 : 2 Metal-Complex Dyes 246

8.3.2.1 Weakly Polar 1 : 2 Dyes 246

8.3.2.2 Strongly Polar 1 : 2 Dyes 246

8.3.2.3 Dye–Fibre Interaction 247

8.4 Environmental Aspects 248

References 248

9 Dyeing Wool with Reactive Dyes 251

D.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

9.3.3.1 Lanasol (CGY, now Huntsman) Dyes 254

9.3.3.2 Drimalan F (S, now Clariant) Dyes 256

9.3.3.3 Realan (DyStar) Dyes 257

9.4 Application Procedures 260

9.4.1 Auxiliary Agents 260

9.4.2 Dyeing Processes used with Reactive Dyes 261

9.4.2.1 Untreated Wool 261

9.4.2.2 Machine-Washable Wool 262

9.4.2.3 Aftertreatment of Dyeings 263

9.4.2.4 Measurement of Dye Fixation 267

9.4.2.5 Novel Processes for use with Reactive Dyes 269

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 Conclusion 287

References 287

10 Dyeing Wool Blends 291

D.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

10.2.2.1 Direct Dyes 297

10.2.2.2 Reactive (Cotton) Dyes 297

10.2.2.3 Vat Dyes 298

10.2.2.4 General Comments 299

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

10.4.2.1 Milling and 1 : 2 Metal-Complex Dyes 309

10.4.2.2 Reactive Dyes 309

10.5 Wool/Nylon 310

10.5.1 Dyeing of Nylon 310

10.5.1.1 Fibre Structure 310

10.5.1.2 Acid Dyes 312

10.5.1.3 Factors Influencing the Dyeing Behaviour of Nylon 314

10.5.1.4 Practical Considerations 317

10.5.2 Dyeing of Wool/Nylon Blends 319

10.5.2.1 Acid Levelling Dyes 319

10.5.2.2 Milling and 1 : 2 Metal-Complex Dyes 321

10.5.2.3 Afterchrome Dyes 322

10.5.2.4 Reactive Dyes 323

10.6 Wool/Polyester 323

10.6.1 Dyeing of Polyester 323

10.6.1.1 Fibre Structure 323

10.6.1.2 Adsorption of Disperse Dyes 325

10.6.1.3 Dispersing Agents 327

10.6.1.4 Levelling Agents 328

10.6.1.5 Carriers 328

10.6.1.6 Machinery 330

10.6.1.7 Continuous Dyeing 330

10.6.1.8 Heat Setting 331

10.6.1.9 Practical Considerations 331

10.6.2 Dyeing of Wool/Polyester Blends 333

10.6.2.1 Dyeing Procedures 333

10.6.2.2 Dyeing Conditions 334

10.6.2.3 The Role of Oxidants in Preventing Setting in Dyeing 335

10.6.2.4 Dye Selection 336

10.6.2.5 Carrier Selection 337

10.6.2.6 Reactive Disperse Dyes for Wool/Polyester Blend

Dyeing 339

10.6.2.7 Novel Arylating Agents for Facilitation of the Dyeing

of Wool and Polyester Fibres with Disperse Dyes 341

10.7 Wool/Acrylic 341

10.7.1 Dyeing of Acrylic Fibres 342

10.7.1.1 Fibre Structure 342

10.7.1.2 Cationic Dyes 344

10.7.2 Dyeing of Wool/Acrylic Blends 348

10.7.2.1 Preparation 348

10.7.2.2 Dyeing Procedures 348

10.7.2.3 Novel Dyeing Techniques for Wool/Acrylic Blends 351

10.8 Conclusion 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

P.J. Broadbent and M.L.A. Rigout

12.1 Introduction 393

12.2 Preparation for Printing 394

12.2.1 Oxidative Processes 394

12.2.1.1 Chlorination with Dichloroisocyanuric Acid 395

12.2.1.2 Kroy Technology 396

12.2.2 Polymer Treatments 396

12.2.2.1 Top Treatment: Chlorination–Hercosett 396

12.2.2.2 Fabric Treatments 397

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

12.3.2.1 Nonreactive Dyes 400

12.3.2.2 Reactive Dyes 400

12.3.2.3 Pigments 401

12.3.2.4 Recipes 401

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

12.5.1.1 Sulphamic Acid Resist Printing 409

12.5.2 Mechanical/Chemical Resist Processes 411

12.5.2.1 Thiotan WS 412

12.5.3 Reactive-Under-Reactive Resist 412

12.6 Digital Printing 412

12.6.1 Machinery 413

12.6.2 Ink Formulation 413

12.6.2.1 Nonreactive Dye-Based Inks 414

12.6.2.2 Reactive Dye-Based Inks 414

12.6.3 Fabric Pretreatment 415

12.6.4 Fixation 417

12.6.4.1 Steaming 417

12.6.4.2 Print-Batch 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

Novel Effects 425

12.10.1 Burn-Out (devor´ee) Printing 425

12.10.2 Sculptured Effects 425

References 426

Index 000

Color plate (between pages xxx and xxx) 000

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