GB483564A - Improvements in the production of valuable dyeings on mixed fabrics - Google Patents

Abstract

Mordant dyes, dyeing with; regenerated celluloses, dyeing.-Mixed fabrics of animal and cellulosic fibres, such as of wool with cotton or regenerated celluloses, are dyed with substantive azo dyestuffs, capable of being chromed, or mixtures thereof with wool dyestuffs capable of being chromed, by using an alkali metal salt of chromic acid, and towards the end of the dyeing process, or in an after-treatment, a salt of trivalent chromium. Suitable salts are chromic fluoride, sulphate, formate, acetate and oxalate, or mixtures of these may be used. Improvements in fastness to water, washing, fulling, sea-water and perspiration by treatment with these salts are readily obtained with dyestuffs containing salicylic acid groups and with o-hydroxyazo dyestuffs. The following examples are specified: (1) a fabric of 70 per cent wool and 30 per cent viscose artificial silk is dyed with the azo dyestuff 4,41-diaminodiphenyl urea (1 mol.) \sQ salicylic acid (2 mols.) in a bath containing sodium chromate and ammonium sulphate and is then treated for 1/2 hour with a solution at 90 DEG C. of chromic sulphate or formate, when the fastness properties are greatly improved. In place of this after-treatment chromic formate may be added to the dyebath near the end of the dyeing process; (2) a fabric of 30 per cent wool and 70 per cent viscose is dyed as in (1) with the use of the dyestuff 1-hydroxynaphthalene-5-sulphonic acid \sM 4,41-diaminodiphenyl-3,31-dicarboxylic acid --> (alkaline) 2-phenylamino-5-hydroxynaphthalene-7-sulphonic acid; the fastness to washing is considerably improved; (3) the fabric of (2) is dyed as in (1) with the use of the dyestuff salicylic acid \sM 4,41-diaminodiphenyl --> (alkaline) 2-(p-cresotinsulphonyl) - amino - 5 - hydroxynaphthalene - 7-sulphonic acid giving bluish dyeings of greatly improved fastness to washing; (4) a fabric of 70 per cent wool and 30 per cent staple fibre is dyed by the metachrome process with a mixture of the substantive dyestuff of the formula <FORM:0483564/IV/1> and the dyestuff 3.4.6 - trichlor - 2 - amino - 1-hydroxybenzene --> 1-acetylamino-8-hydroxynaphthalene-4-sulphonic acid giving greenish-blue to navy blue shades and after-treated in a separate bath containing chromic fluoride to improve the fastness to washing etc.; alternatively, chromic sulphate may be added to the metachrome bath near the end of the dyeing process. It is also possible to dye the fabric with the dyestuff mixture from a neutral or weakly acid bath, add sodium bichromate and then treat in a second bath with chromic sulphate, or the bichromate may be in the second bath and the chromic sulphate added towards the end of the treatment. 2 - (p - Cresotinsulphonyl) - amino - 5 - hydroxynaphthalene-7-sulphonic acid is obtained by condensing 2-amino-5-hydroxynaphthalene-7-sulphonic acid with p-cresotinic acid sulphochloride.