Pretreatment of Textile Substrates
by Mathews Kolanjikombil
Contents
Preface xiii
PART I 1
1 Pretreatment of Cellulosics – Singeing & Desizing 3
1.1 Cotton 4
1.1.1 Composition of cotton 4
1.1.2 Other impurities added to cotton during weaving orknitting 8
1.2 Singeing 11
1.2.1 Plate singeing 11
1.2.2 Roller singeing 12
1.2.3 Gas singeing 13
1.2.4 Important gas singeing parameters 15
1.2.5 Essential conditions for good gas singeing 15
1.2.6 Important care to be taken while singeing 15
1.2.7 Bio-wash 17
1.2.8 Demineralisation 17
1.2.9 Potential sources of metallic impurities 18
1.3 Hardness in cotton 18
1.3.1 Effect of metal ions in preparation 18
1.3.2 Desizing 20
1.3.3 Main characteristics of sizes 20
1.3.4 Sizing requirements 20
1.3.5 Needs of subsequent processes 21
1.3.6 Starches 22
1.3.7 Modified starches 24
1.3.8 Cellulose derivatives 25
1.3.9 Alginates 26
1.3.10 Polyvinyl alcohols 26
1.3.11 Polyacrylates 27
1.3.12 Polyester (PES) 28
1.4 Size possibilities in different fibres 29
1.5 Common sizing materials and their detection 30
1.5.1 Detection of size on the fabric surface 30
1.5.2 Size detections in the aqueous extract 37
1.5.3 Methods of extraction 38
1.5.4 Test and observations 38
1.6 Cotton desizing process 43
1.6.1 Enzymatic desizing 43
1.6.2 Batch wise processes 47
1.6.3 Guideline recipes 48
1.6.4 Semi-continuous and continuous processes 52
1.6.5 Pad batch or pad-steam methods 53
1.7 Acid desizing 56
1.7.1 Water soluble starches 56
1.7.2 Continuous processes 58
1.8 Oxidative desizing 59
1.8.1 Desizing with hydrogen peroxide (oxidative shockdesizing) 64
1.8.2 Bromite desizing 66
1.8.3 Desizing of garments 67
1.8.4 Iodine test for starch–TEGEWA violet scale 68
PART II 71
2 Pretreatment of cellulosics -Mercerising and scouring 73
2.1 Mercerising and causticising 73
2.1.1 The advantages of mercerisation 73
2.1.2 Mercerisation methods 76
2.1.3 The practical mercerisation process 80
2.1.4 Changes in the properties of cellulose due to mercerisation 87
2.1.5 Mercerising machines 88
2.1.6 Hank mercerising 92
2.1.7 Cheese mercerisation 93
2.1.8 Single end mercerisation 93
2.1.9 Warp mercerisation 94
2.1.10 Chainless/roller mercerising machine 94
2.1.11 Chain mercerizing machine 96
2.1.12 Merceriser with combined chainless–Chain combination 99
2.1.13 Batch mercerisers 100
2.1.14 Mercerising knitted fabrics 101
2.1.15 Stenter mercerising (SM) process 105
2.1.16 Caustic recovery 107
2.1.17 Ammonia mercerisation 112
2.1.18 Prograde process–J. & P. Coats Ltd. (Scotland) 114
2.1.19 Sanforset process 115
2.1.20 Weight reduction (deweighting) of polyester 116
2.1.21 Continuous reductive causticising process (CRC process) 119
2.1.22 One bath causticisation and bleaching (CBF process) 122
2.2 Scouring 123
2.2.1 Chemicals for alkaline scour boiling 125
2.3 Batch wise process 143
2.3.1 Alkaline scouring 143
2.3.2 Acid scouring 145
2.3.3 Continuous scouring 149
2.3.4 Preparation of cotton knitted goods 154
PART III 159
3 Pretreatment of Cellulosics – Bleaching 161
3.1 Bleaching of cellulosics 161
3.1.1 Hypochlorites 162
3.1.2 Bleaching powder 166
3.1.3 Sodium chlorite 166
3.1.4 Chlorite bleaching–Theory 167
3.1.5 Open-width bleaching using sodium chlorite 171
3.2 Hydrogen peroxide (H-O-O-H) 176
3.2.1 Mechanisms 177
3.2.2 Physical and chemical properties of hydrogen peroxide invarious forms 178
3.2.3 Decomposition of hydrogen peroxide 180
3.2.4 Stabilisation of bleaches and bleach liquors 181
3.2.5 Stabilisation of hydrogen peroxide 182
3.2.6 Inorganic stabilisers 182
3.2.7 Organic stabilisers 186
3.2.8 Persulphates 189
3.2.9 Peracetic acid 190
3.2.10 Potassium permanganate 194
3.2.11 Ozone bleaching 194
3.3 Reductive bleach 194
3.4 Bleaching methods with peroxides 205
3.4.1 Peroxide requirements for various processes of cotton bleaching 205
3.4.2 Cold peroxide bleach 205
3.4.3 Cold peroxide bleach–Pad roll–Cotton, Polyester/cotton wovens 205
3.4.4 Continuous desizing and cold pad batch bleaching (CPB) 207
3.4.5 Process calculations 208
3.4.6 Discontinuous methods 211
3.4.7 Bleaching knit goods on overflow machines (batch process)–Peroxide 212
3.4.8 Combined boil-off and bleaching 213
3.4.9 Continuous cold peroxide bleach 215
3.4.10 Hot peroxide bleaches 216
3.4.11 Continuous hydrogen peroxide bleach 217
3.4.12 Bleaching of knitted goods 223
3.4.13 Continuous bleaching machineries for knitted goods 226
3.4.14 Bleaching with hypochlorites 231
3.4.15 Available chlorine and active chlorine 235
3.4.16 The preparation of viscose and blends of viscose 244
3.4.17 Pre-treatment of Bamboo Fibres 258
PART IV 261
4 Pretreatment of Substrates – Other Natural fibres 263
4.1 Pre-treatment of linen/flax 263
4.1.1 Features of linen 263
4.1.2 Enzymatic desizing/enzymatic scouring 266
4.1.3 Bleaching 268
4.1.4 Quality tests for the efficiency of preparation (cotton) 273
4.2 Pre-treatment and bleaching of wool and silk 277
4.2.1 Preparation of wool and woollen blends 277
4.3 Silk 292
4.3.1 Structure of silk 293
4.3.2 Chemical composition of mulberry silk 293
4.3.3 Preparation 294
4.3.4 Bleaching 303
PART V 309
5 Pretreatment of the substrates – synthetic fibres 311
5.1 Preparation of synthetic fibres and their blends 311
5.1.1 Pretreatment of Polyester 311
5.1.2 Preparation of polyamide 319
5.1.3 Preparation of polyester goods 322
5.1.4 Pre-treatments of polyester knitted fabrics 324
5.2 Preparation of synthetic blends 328
5.2.1 Pre-treatment of polyester/cotton (cellulosic) blends 328
5.2.2 Preparation polyester/acetate blends 333
5.2.3 Pre-treatment of polyester/triacetate blends 334
5.2.4 Pre-treatment of polyester/acrylic blends 334
5.2.5 Pre-treatment of wool/acetate blends 337
5.2.6 Pre-treatment polyester/polyamide blends 337
5.2.7 Pre-treatment of polyester/wool blends 338
5.2.8 Pre-treatment of acrylic/cellulosic blends 345
5.2.9 Pre-treatment of acrylic/wool blends 346
5.2.10 Pre-treatment of acrylic/polyamide 348
5.2.11 Pre-treatment of acrylic/acetate blends 350
5.2.12 Pre-treatment of acrylic/triacetate blends 351
5.2.13 Recipes for pre-treatments for various blends 353
5.2.14 Optical whitening 359
5.2.15 Energy diagram of optical brighteners and transitions 362
5.2.16 Polyester/cellulosic blends 371
5.2.17 Preparation of elastane fabric 373
5.2.18 Pad-batch cold demineralising 385
5.2.19 Scouring 385
5.2.20 Bleaching 386
5.2.21 Combined scouring/bleaching of elastane fabrics 389
5.2.22 Modern continuous bleaching 391
PART VI 405
6 Pretreatment of substrates – biopreparation and other technologies 407
6.1 Bio-preparation 407
6.1.1 How an enzyme works 410
6.1.2 Mechanism of enzyme action 413
6.1.3 Enzyme activators and inhibitors 414
6.2 Cotton fibre morphology 415
6.2.1 Primary wall 416
6.2.2 Enzymes 417
6.3 Bio-preparation 418
6.3.1 Properties of enzymatic scoured fabrics 419
6.3.2 Bio-preparation on Jet dyeing 422
6.3.3 General yarn Bio-preparation procedure 424
6.3.4 Simultaneous yarn Bio-preparation and dyeing procedure 425
6.3.5 Pad-roll Bio-preparation procedure 425
6.3.6 Other bio-treatments–Wool 428
6.3.7 Other bio-treatments–Silk 429
6.3.8 Other bio-treatments–Polyester 431
6.3.9 Other bio-treatments 431
6.3.10 Other bio-treatments–Retting of flax 431
6.3.11 Surface modification of cashmere fibres 432
6.3.12 Enzyme fading 434
6.3.13 Solvent scouring 437
6.4 Mineral earth – Technology for preparation of cellulosics 439
6.4.1 Characteristics 440
6.5 Emerging technologies 441
References 447
Index 453