Textile dyes

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 Vinylsulphone dyes......Page 8
 Quinphthalone dyes......Page 9
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Dyes & Colour......Page 13
Otto Witt theory of colour (1876):......Page 14
C6H5 – N = N – C6H5......Page 16
Valence bond approach to colour:......Page 17
History of Dyestuff......Page 19
Classification of Dyes......Page 34
Wool Fibres:......Page 59
Silk Fibres:......Page 60
Cellulosic Fibres:......Page 61
Monoazso Dyes:......Page 63
Dyes with Mixed Chromophores:......Page 64
Cellulose Acetate Fibres:......Page 66
Cellulose Triacetate Fibres:......Page 68
 In the course of the exploratory work that led to the development of nylon W.H. Carothers examined aliphatic polyesters but abandoned them in favour of the more promising polyamides. Subsequently, however, the late J.R. Whinfield and J.T. Dickson of The Calico Printers’ Association re-examined polyesters for the purpose. They extended the work to aromatic compounds and obtained a polymer with excellent fibre-forming properties from terephthalic acid and ethyleneglycol. This has the structure (3).  The important fibre ‘Terylene’ was based on this......Page 70
Polypropylene Fibres:......Page 71
Polyacrylonitrile Fibres:......Page 72
How do dyes stick to fibres?......Page 73
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Reactive Dyes......Page 75
Devising of dyebath conditions, which, while bringing about the formation of a covalent bond, were mild enough to avoid serious damage to the fibre. The dyeings were carried out at ordinary temperatures, ‘fixation’ being brought about by the addition of sodium bicarbonate, thus raising the pH. The reaction with cellulose may be represented as nucleophilic substitution by the attaching species RO- or HO- where R = cellulose moiety. Attach by HO-, derived from the water of the dyebath, occurs simultaneously, but that of cellulose onion predominates since the dye is absorbed by the cellulose fibres and dye-substrate reaction is therefore facilitated. It is necessary to remove hydrolysed unfixed dye by through soaping and washing otherwise inferior fastness to wet treatment results.  An example of a Procion M dye is the following:......Page 76
The chlorotriazinyl reactive dyes are by far the most important class and have proved a serious rival to the vat dyes as regards wash-fastness and in other ways. The main chromogens employed are azo, metal-azo, anthraquinone and phthallocyanine systems. The question of cotton substantivity is an important one. It should be high enough to ensure a high ‘fixation-yield’ but at the same time a substantivity of the unfixed, hydrolysed dye should be low enough to permit easy removal by soaping and rinsing to ensure maximum fastness to wet treatments in the finished dyeing. Structural modifications to the molecule, which (a) inhibit coplanarity or (b) increase the water-solubility, tend to reduce substantivity.......Page 77
Nucleophilic substitution systems:......Page 78
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Evidence for chemical combination......Page 82
COMMERCIAL POPULAR REACTIVE DYES......Page 84
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Chemical constitution of direct dyes:......Page 99
CLASSIFICATION ACCORDING TO DYEING BEHAVIOUR......Page 101
Disperse Dyes......Page 104
Vat Dyes......Page 113
Sulphur Dyes......Page 122
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Acid (Anionic) Dyes......Page 129
Basic (Cationic Dyes)......Page 136
Banned Amines......Page 139
COLOURFASTNESS:......Page 155
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pH, initial......Page 158
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Procedures:......Page 161
Test......Page 162
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Lightfastness:......Page 164
Less than......Page 165
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     M p = 100 ------------------......Page 178