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Tanning Chemistry: The Science of Leather [Kietas viršelis]

  • Formatas: Hardback, 520 pages, aukštis x plotis: 234x156 mm, weight: 895 g, Not illustrated
  • Išleidimo metai: 19-Jun-2009
  • Leidėjas: Royal Society of Chemistry
  • ISBN-10: 0854041702
  • ISBN-13: 9780854041701
Kitos knygos pagal šią temą:
  • Formatas: Hardback, 520 pages, aukštis x plotis: 234x156 mm, weight: 895 g, Not illustrated
  • Išleidimo metai: 19-Jun-2009
  • Leidėjas: Royal Society of Chemistry
  • ISBN-10: 0854041702
  • ISBN-13: 9780854041701
Kitos knygos pagal šią temą:
Even in the 21st Century, the manufacture of leather retains an air of the dark arts, still somewhat shrouded in the mysteries of a millennia old, craft based industry. Despite the best efforts of a few scientists over the last century or so, much of the understanding of the principles of tanning is still based on received wisdom and experience. Leather is made from (usually) the hides and skins of animals - large animals such as cattle have hides, small animals such as sheep have skins. The skin of any animal is largely composed of the protein collagen, so it is the chemistry of this fibrous protein and the properties it confers to the skin with which the tanner is most concerned. In addition, other components of the skin impact on processing, impact on the chemistry of the material and impact on the properties of the product, leather. Therefore, it is useful to understand the relationships between skin structure at the molecular and macro levels, the changes imposed by modifying the chemistry of the material and the eventual properties of the leather. This book aims to contribute to changing the thinking in the industry, to continue building a body of scientific understanding, aimed at enhancing the sustainability of an industry which produces a unique group of materials, derived from a natural source. The Science of Leather is the only current text on tanning science, and addresses the scientific principles which underpin the processes involved in making leather. It is concerned with the chemical modification of collagen, prior to tanning and the tanning reactions in particular. The subject is covered in the following order: collagen chemistry, collagen structure, skin structure, processing to prepare for tanning, the tanning processes and processing after tanning. The aim of the book is to provide leather scientists and technologists with an understanding of how the reactions work, the nature of their outcomes and how the processes can be controlled and changed. The objective is to synthesise a scientific view of leather making and to arrive at an understanding of the nature of tanning - how the wide range of chemistries employed in the art can change the properties of collagen, making leather with different properties, especially conferring different degrees of stabilisation as measured by the hydrothermal stability. Environmental issues are not treated as a separate theme - the impact of leather making on the environment is a thread running through the text, with the assumption that better understanding of the science of leather making will lead to improved processing. The book also reflects on the ways leather technology may develop in the future based on the foundation of understanding the scientific principles which can be exploited. It also includes a subject index, references and a glossary. The book provides the reader with insights into the role science plays in leather technology and provides fundamental understanding, which should be the basis for scientific and technological research and development for the benefit of the global leather industry. The book is aimed at students, leather scientists and technologists, in both academia and industry, in leather production and in chemical supply houses.

Written by the leading expert in the field, this is the only current text on tanning science.

Recenzijos

"...book is an undoubtedly successful update..." * Journal of the Society of Leather Technologists *

Chapter 1 Collagen and Skin Structure 1
1.1 Introduction
1
1.2 Hierarchy of Collagen Structure
4
1.2.1 Amino Acid Sequence
4
1.2.2 The α-Helix
6
1.2.3 The Triple Helix
6
1.3 Isoelectric Point
8
1.4 Collagen and Water
10
1.5 Quarter Stagger Array
14
1.6 Fibrils
17
1.7 Fibril Bundles
20
1.8 Fibres
20
1.9 Other Collagens
20
1.9.1 Type III Collagen
20
1.9.2 Type IV Collagen
21
1.9.3 Type VII Collagen
21
1.10 Chemistry of Collagen
21
1.11 Hydrothermal Stability
23
References
27
Chapter 2 Skin and its Components 29
2.1 Introduction
29
2.1.1 Epidermis
29
2.1.2 Grain
30
2.1.3 Junction
33
2.1.4 Corium
35
2.1.5 Flesh Layer
35
2.1.6 Flesh
35
2.2 Skin Features and Components
36
2.2.1 Hair or Wool
36
2.2.2 Follicles
36
2.2.3 Erector Pili Muscle
36
2.2.4 Sweat Glands
36
2.2.5 Veins and Arteries
37
2.2.6 Elastin
38
2.3 Non-structural Components of Skin
42
2.3.1 Glycosaminoglycans (GAGs)
42
2.3.2 Hyaluronic Acid
42
2.3.3 Dermatan Sulfate
44
2.3.4 Chondroitin Sulfate A
44
2.3.5 Chondroitin Sulfate C
45
2.3.6 Melanin
45
2.4 Skin
48
2.4.1 Area of Skin or Leather
51
2.5 Processing
54
2.5.1 Splitting
54
2.5.2 Grain–Corium Thickness Ratio
55
2.5.3 Fleshing
56
2.5.4 Dung
56
2.6 Variations in Skin Structure due to Species
65
2.6.1 Hereford Cattle and Vertical Fibre
65
2.6.2 Sheepskin
67
2.6.3 Cutaneous Fat
67
References
69
Chapter 3 Curing and Preservation of Hides and Skins 72
3.1 Introduction
72
3.2 Drying
76
3.3 Salting
79
3.3.1 Stacking
80
3.3.2 Drum Curing
81
3.3.3 Types of Salt
82
3.3.4 Additives for Salt
85
3.3.5 Dry Salting
85
3.3.6 Brining
85
3.4 Alternative Osmolytes
86
3.5 pH Control
87
3.6 Temperature Control
89
3.6.1 Chilling
89
3.6.2 Icing
90
3.6.3 Biocide Ice
90
3.6.4 Freezing
90
3.7 Biocides
91
3.8 Radiation Curing
91
3.9 Fresh Stock
92
References
93
Chapter 4 Soaking 95
4.1 Introduction to Beamhouse Processing
95
4.2 Soaking Process
96
4.2.1 Rehydration
99
4.2.2 Removal of Salt
99
4.2.3 Cleaning the Pelt
101
4.2.4 Removal of Non-structural Proteins
101
4.2.5 Removal of Dung
101
4.2.6 Removal of Hyaluronic Acid
102
4.3 Conditions in Soaking
102
4.3.1 Long Float
102
4.3.2 Change of Float
103
4.3.3 Temperature
103
4.3.4 pH
103
4.3.5 Time
103
4.3.6 Mechanical Action
103
4.4 Components of Soaking Solutions
104
4.4.1 Water
104
4.4.2 Detergents
105
4.4.3 Soaking Enzymes
106
4.4.4 Biocides
107
4.5 Role of the Erector Pili Muscle
109
References
111
Chapter 5 Unhairing 112
5.1 Introduction
112
5.2 Keratin and the Structure of Hair
112
5.3 Hair Burning
118
5.3.1 Role of Swelling
122
5.3.2 Chemical Variations
123
5.4 Immunisation
124
5.5 Hair Saving
125
5.6 Variations in Unhairing Technologies
126
5.6.1 Heidemann's Darmstadt Process
126
5.6.2 Oxidative Unhairing
127
5.6.3 Reductive Unhairing
128
5.6.4 Acid Unhairing
128
5.7 Enzymes in Unhairing
128
5.7.1 Enzyme-assisted Chemical Unhairing
128
5.7.2 Chemical-assisted Enzyme Unhairing
129
5.7.3 Enzyme Hair Saving
129
5.7.4 Keratinase
130
5.8 Painting
130
5.9 Role of Shaving in Unhairing
131
References
132
Chapter 6 Liming 134
6.1 Introduction
134
6.1.1 Float
134
6.1.2 pH
135
6.1.3 Temperature
136
6.1.4 Time
136
6.2 Purposes of Liming
136
6.2.1 Removal of Non-collagenous Components of the Skin
138
6.2.2 Splitting the Fibre Structure at the Level of the Fibril Bundles
139
6.2.3 To Swell the Pelt
139
6.2.4 Hydrolysis of Peptide Bonds
143
6.2.5 Hydrolysis of Amide Sidechains
143
6.2.6 Hydrolysis of Guanidino Sidechains
148
6.2.7 Removal of Dermatan Sulfate
148
6.2.8 Fat Hydrolysis
149
6.3 Variations in Liming
149
6.3.1 Chemical Variations
149
6.3.2 pH Variations
150
6.3.3 Biochemical Variations
150
6.4 Limeblast
151
References
153
Chapter 7 Deliming 154
7.1 Introduction
154
7.2 Deliming Agents
155
7.2.1 Water
156
7.2.2 Strong Acids
156
7.2.3 Weak Acids
157
7.2.4 Acidic Salts
157
7.2.5 Ammonium Salts
158
7.2.6 Alternative Buffers
159
7.2.7 Hydroxyl 'Sinks'
160
7.2.8 Carbon Dioxide
161
7.3 Melanin
164
7.4 Limeblast
165
References
165
Chapter 8 Bating 166
8.1 Introduction
166
8.2 Factors Affecting Enzyme Catalysis
169
8.2.1 Temperature
169
8.2.2 pH
170
8.2.3 Concentration: Bate Formulation
171
8.2.4 Time
172
8.2.5 Origin
172
8.3 Monitoring Bating
173
8.4 Enzyme Assays
174
References
176
Chapter 9 Pickling 177
9.1 Introduction
177
9.2 Processing Conditions
179
9.2.1 Float
179
9.2.2 Salt
179
9.3 Lyotropic Swelling
184
9.4 Sulfuric Acid
185
9.5 Hydrochloric Acid
186
9.6 Formic Acid
186
9.7 Colour
188
9.8 Non-swelling Acids
190
9.9 Pickle Formulations
192
9.10 Implications for Chrome Tanning
193
References
194
Chapter 10 Tanning 195
10.1 Introduction
195
10.2 Hydrothermal Stability
196
10.2.1 Shrinkage Temperature (Ts)
198
10.2.2 Boil Test
199
10.2.3 Differential Scanning Calorimetry
200
10.2.4 Hydrothermal Isometric Tension
201
References
202
Chapter 11 Mineral Tanning: Chromium(m) 204
11.1 Introduction
204
11.2 Preparation of Chrome Tanning Salts
205
11.3 Brief Review of the Development of Chrome Tanning
208
11.4 Chromium(m) Chemistry
209
11.5 Chrome Tanning Reaction
213
11.6 Basification
221
11.6.1 Soluble Alkaline Salts
223
11.6.2 Carboxylate Salts
224
11.6.3 Other Basic Salts
225
11.6.4 Self-basifying Salts
225
11.7 Avoiding Basification
228
11.8 Reactivity at High Basicity
228
11.9 Role of Temperature
230
11.10 Relative Effects of pH and Temperature
231
11.11 Masking
237
11.11.1 Polycarboxylates
243
11.12 Stability of Chrome Tanned Leather
246
11.13 Role of Sulfate in the Chrome Tanning Mechanism
247
11.14 Role of the Counterion in Chrome Tanning
250
11.15 Role of the Solvent
252
11.16 Zero Float Processing
252
11.17 Non-aqueous Floats
253
11.18 Role of Ethanolamine
255
11.19 Nature and State of the Substrate
255
11.19.1 Modifying the Substrate
255
References
256
Chapter 12 Mineral Tanning 259
12.1 Introduction
259
12.1.1 Blocks and Groups of the Periodic Table
260
12.2 Experimental Tanning Reviews
265
12.3 Aluminium in Leather Making
267
12.3.1 Alum Pickle
269
12.3.2 Suede
269
12.3.3 Furskins
269
12.3.4 Semi-alum Tannage
270
12.3.5 Chrome Uptake
270
12.4 Titanium Tanning
274
12.5 Zirconium Tanning
275
12.6 Iron Tanning
276
12.7 Mixed Mineral Tannages
277
12.8 Overview
278
References
278
Chapter 13 Vegetable Tanning 281
13.1 Introduction
281
13.2 Vegetable Tannin Classification
284
13.2.1 Hydrolysable Tannins
284
13.2.2 Condensed Tannins
288
13.2.3 Complex Tannins
293
13.3 General Properties of Vegetable Tannins
293
13.4 Practical Vegetable Tanning
294
13.5 Modern Pit Tanning
295
13.5.1 Counter-current Pit Tanning
295
13.6 Other Vegetable Tanning Technologies
296
13.7 Combination Tanning
296
13.7.1 Semi-metal Tanning
296
13.7.2 General Properties of Semi-metal Leathers
300
13.7.3 Semi-chrome Tanning
301
13.8 Condensed Tannins and Aldehydic Crosslinkers
303
13.9 Biodegradability
310
13.10 Effluent Treatment
313
References
313
Chapter 14 Other Tannages 315
14.1 Oil Tanning
315
14.2 Sulfonyl Chloride
317
14.3 Syntans
318
14.3.1 Auxiliary Syntans
323
14.3.2 Retans
324
14.3.3 Replacement Syntans
324
14.3.4 Other Syntans
324
14.4 Resins
326
14.5 Aldehydes and Aldehydic Tanning Agents
328
14.5.1 Introduction
328
14.5.2 Formaldehyde
329
14.5.3 Glutaraldehyde
331
14.5.4 Other Aliphatic Aldehydes
332
14.6 Aldehydic Tanning Agents
334
14.6.1 Oxazolidines
334
14.6.2 Phosphonium Salts
337
14.7 Other Tanning Applications: Wet White
338
14.7.1 Wet White Production
339
14.7.2 Use of Part Processed Materials
342
14.8 Miscellaneous Tannages
342
14.8.1 Epoxide Tanning
342
14.8.2 Isocyanate Tannage
343
14.8.3 Multi-functional Reagents
345
References
345
Chapter 15 Post Tanning 348
15.1 Definition
348
15.2 Relationship between Tanning and Post Tanning
349
15.3 Chrome Retanning
351
15.4 Sequence of Post Tanning Steps
352
15.5 Principles of Post Tanning
353
15.5.1 Mechanisms of Post Tanning
353
15.5.2 Role of the Isoelectric Point
356
15.5.3 Role of the Peptide Link
359
15.5.4 Role of the Sulfonate Group
359
15.5.5 Coordinating Post Tanning Processes
360
15.6 Compact Processing
362
15.6.1 Neutralise and Retan
362
15.6.2 Retan and Dye
362
15.6.3 Retan and Fatliquor
363
15.6.4 Dye and Fatliquor
363
15.6.5 Retan, Dye and Fatliquor
363
15.7 Role of Processing on Leather Properties: Dynamic Mechanical Thermal Analysis
364
References
368
Chapter 16 Dyeing 370
16.1 Introduction
370
16.2 Acid Dyes
373
16.3 Basic Dyes
373
16.4 Direct Dyes
374
16.5 Mordant Dyes
375
16.6 Premetallised Dyes
377
16.6.1 1:1 Premetallised Dyes
377
16.6.2 1:2 Premetallised Dyes
378
16.7 Reactive Dyes
379
16.8 Sulfur Dyes
382
16.9 Dye Reactivity and Fixation
383
16.10 Role of the Substrate
384
16.10.1 Chrome Tanned Leather
384
16.10.2 Vegetable Tanned Leather
385
16.10.3 Other Tannages
385
16.11 Dyeing Auxiliaries: Levelling and Penetrating Agents
385
16.11.1 Anionic Auxiliaries
385
16.11.2 Auxiliaries that Complex with Dyestuff
387
16.11.3 Auxiliaries that have Affinity for both Leather and Dye
387
16.11.4 Intensifying Agents
387
16.11.5 Cationic Tannages
388
16.11.6 Cationic Auxiliaries
388
16.12 Alternative Colouring Methods
389
References
391
Chapter 17 Fatliquoring 392
17.1 Introduction
392
17.2 Anionic Fatliquors
401
17.2.1 Sulfated Fatliquors
401
17.2.2 Sulfited Oils
404
17.3 Soap Fatliquors
405
17.4 Cationic Fatliquors
405
17.5 Nonionic Fatliquors
406
17.5.1 Alkyl Ethylene Oxide Condensates
406
17.5.2 Protein Emulsifiers
407
17.6 Multi-charged Fatliquors
407
17.7 Amphoteric Fatliquors
407
17.8 Solvent Fatliquors
407
17.9 Complexing Fatliquors/Water Resistance Treatments
408
17.10 Water Resistance
409
17.10.1 Introduction
409
17.10.2 Principles of Conferring Water Resistance
411
17.10.3 Chemistries of Water Resistance Treatments
416
17.10.4 Chrome Tanned Leather
417
17.10.5 Non-chrome Tanned Leather
419
References
420
Chapter 18 Drying 421
18.1 Two-stage Drying
427
18.2 Conclusion
430
References
430
Chapter 19 Theory of Tanning: Concept of Link-Lock 432
19.1 Introduction
432
19.2 Discussion
435
19.3 Conclusions
441
References
441
Chapter 20 The Future of Leather Processing 444
20.1 Future of Chrome Tanning
444
20.2 Other Mineral Tanning Options
445
20.3 Non-chrome Tanning for 'Chrome Free' Leather
446
20.4 Single Tanning Options
447
20.5 Tanning Combinations
448
20.6 Leather Properties
450
20.7 Organic Tanning Options
451
20.7.1 Polyphenol Chemistry
451
20.7.2 Polymer and Crosslinker
453
20.8 Natural Tanning Agents
454
20.8.1 Carbohydrates
454
20.8.2 'Bog Body' Chemistry
455
20.8.3 Nor-dihydroguaiaretic Acid (NDGA)
456
20.8.4 Genepin
459
20.8.5 Oleuropein
459
20.9 Other Reagents
461
20.10 Compact Tanning
462
20.11 Alternative Technologies
462
20.12 Overview
464
20.13 Conclusions
464
References
465
Subject Index 467
Anthony D Covington is Emeritus Professor of Leather Science at the University of Northampton, UK. The book is the culmination of a 40 year career in chemistry and the leather industry which started with a graduateship of the Royal Institute of Chemistry (now the Royal Society of Chemistry) at Teesside Polytechnic (now the University of Teesside). He continued his chemistry experience with doctoral studies in physical organic chemistry at Stirling University, followed by post doctoral research in physical chemistry at the University of Newcastle upon Tyne. Professor Covington then joined the British Leather Manufacturers' Association (later to become BLC The Leather Technology Centre of Northampton, UK), where he spent 18 years engaged in research and development, industrial consultancy and problem solving in the UK and overseas. From 1995-7, he was President of the International Union of Leather Technologists and Chemists Societies (IULTCS) and since 1995 he has been with the British School of Leather Technology of the University of Northampton. Professor Covington has 21 doctoral completions and 230 technical publications to his name.