Bleaching and dyeing; fluid treatment and chemical modification – Dye or potential dye composition – additive – treatment,... – Sulfur dye or vat dye
Patent
1997-01-14
1999-02-23
Einsmann, Margaret
Bleaching and dyeing; fluid treatment and chemical modification
Dye or potential dye composition, additive, treatment,...
Sulfur dye or vat dye
8921, 8922, 8924, 8925, 8926, D06P 122, D06P 324, D06P 340, D06P 352
Patent
active
058739149
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a novel methods for dyeing non-cellulosic organic materials, such as nylon, polyester, acetates, acrilan, viscose, polyolefins, polyurethanes and polyarylamides. It also relates to dyed materials, particularly to novel dyed non-cellulosic organic materials having improved properties achievable by means of the dyeing process.
Conventional vat dyeing methods are well known to be incapable of providing satisfactory lightfastness and washfastness when used with synthetic fabrics, for example nylon and polyester. This causes problems when applying such dyes to synthetic materials commercially. Car interiors and upholstery, and curtains and drapes in homes, trains and ships often comprise synthetic fabrics that by their nature are exposed to bright sunlight for long periods. Hardwearing synthetic carpets, particularly those in communal areas, require good light and shampoo fastness, yet often include metal based compounds to increase light fastness that are washed out with cleaning. Furthermore, modern synthetic fabrics such as microfibre nylon, polyurethanes such as Lycra (RTM) and polyarylamides such as Kevlar (RTM) and Nomex (RTM) are notoriously difficult to dye. With fibres of materials such as Lycra it is conventional to blend them with fibres of more easily dyed material eg. cellulosic fibres such as cotton, in order to allow satisfactory dyeing to be achievable.
The option of applying vat dyes to synthetic materials such as nylon, Kevlar (RTM), Nomex (RTM), polyolefins, polyurethanes and polyester with the prospect of wash- and lightfastness been discounted in the art; see for example "Textile Printing with Caledon, Durindone and Soledon Dyes" (1961) p391, paragraph 17.9 and "Dyeing Synthetic Polymers and Acetate Fibres", Ed D M Nunn, Dyers Company Publication Trust 1979.
The dyeing synthetic materials is also important in specialised areas eg. the provision of clothing for service personnel. In this field materials are also dyed to improve their near infra-red camouflage characteristics by reducing reflectance at certain atmospheric `window` wavelengths. On cotton and cellulosic blended fibre fabrics this can be readily carried out by vat dyeing as vat dyes comprise large conjugated ring structures which confer correct reflectance properties. However, it has always been difficult to achieve near infra-red reflectance camouflage with synthetic materials such as nylon and polyester as the dyes which are effective in colouring them comprise relatively small molecules.
Use of small concentrations of black vat dye on cottons is sufficient to control near infra-red properties. However, using standard vat dyes and vat dyeing conditions it has hitherto not been possible to achieve light fastness of greater than 5 (British Standard Test BS 1006: (1978) B01:B02) when dyeing nylon, while wash fastness at 60.degree. C. has been limited to 4 to 5 (British Standard Test BS 1006: 1978: C06). Thomas Vickerstaff `The Physical Chemistry of Dyeing` (1968) 2nd Edition, p479, Table 125 shows lightfastness of vat dyed nylon to be no better than 2 to 3 for a range of colours where the corresponding cotton has fastness of 5 to 8.
In order to render nylon filament fabrics near infra-red camouflaged several techniques have been applied. A first one of these techniques incorporates carbon black pigment into the printing paste. However the carbon is difficult to apply and the low reflectance fastness is poor. In a second method of more limited application pigments are indirectly applied by incorporation into polymer coatings or membranes applied to the fabric. A third method includes a proportion of black pigmented nylon yarns into woven structures, thus necessitating careful weaving to completely mask them in the final product. All these techniques cause problems in production and are inconvenient.
Specialised dyed materials have been produced, as described in JP03076880, although the method described is not generally applicable and only a small group of particular materials can be dyed according
REFERENCES:
patent: 5607483 (1997-03-01), Burkinshaw et al.
Baumgarte Melliand Textile Reports, Mar. 1987, pp. 189-195 "Reduction and Oxidation processes in Dyeing with Vat Dyes".
Baumgarte Melliand Textile Reports 68 (no month available 1987) pp. 187-195 "Reduction and Oxidation processes in Dyeing with Vat Dyes".
Baumgarte 4052 Review of Process in . . . 17 (no month available 1987) Developments in Vat Dyes and in their application 1974-1986.
Aspland 2248 Textile Chemist and Colorist 24 ( 1992 Jan.), No. 1, Triangle Part, NC "Chapter 3: Vat Dyes and their applications".
Brown Philip J.
Burkinshaw Stephen M.
Einsmann Margaret
The Secretary of State for Defence in Her Britannic Majesty's Go
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