GB476428A - Manufacture and application of new azo dyestuffs - Google Patents

Abstract

Monoazo dyes; acid wool and mordant dyes, dyeing with.--Monoazo dyes, suitable for dyeing furs, pelts or hair, are obtained by coupling diazotized 4-nitro-4<1>-aminodiphenylamine-2-sulphonic acid with an aminonaphthol, free from sulphonic or carboxylic acid groups or with an N-alkyl-, N-hydroxyalkyl-, N-aryl or N-acylderivative thereof. The dyeings are red, red-violet and violet to brown shades of good solidity, evenness and fastness to light and rubbing. The materials may be subjected before dyeing, to the usual "killing" treatment with soda ash, ammonia, lime or caustic soda, followed, after neutralizing with acid, by a "chrome-tannage," e.g. with chrome alum, an alkali bichromate or basic chromium sulphate and, if necessary, neutralization with sodium bicarbonate; they may be further treated with agents such as hypochlorites or phosphates to increase the dyeing capacity of the hair fibres. Examples are given of the manufacture of the dyestuffs with the use, as coupling component, of (1) 1 : 5-aminonaphthol (coupled alkaline), (2) 1 : 5-aminonaphthol (coupled acid), (3) 2 : 7-aminonaphthol (coupled alkaline). In examples of the dyeing process (a) a chrome-tanned long-haired white rabbit fur is entered into a bath at 40 DEG C. containing the dyestuff of (1) above, the temperature is raised during 20 minutes to 75 DEG C., and so maintained for 100 minutes with an addition of acetic acid after the first 30 minutes and of formic acid after a further 30 minutes; the fur is then removed, dried and drummed in sawdust; (b) a chrome-tanned shorn white rabbit fur is entered into a bath at 40 DEG C. containing the dyestuff, 4-nitro-4<1>-aminodiphenylamine - 2 - sulphonic acid --> (alkaline) 1-b -hydroxyethylamino-5-naphthol, dyeing is effected as in (a) at a temperature of 55--60 DEG C., and the fur is then removed, dried and drummed as in (a). A table is also given showing the shades obtainable on fur with the use of the dyestuffs having as coupling components, 1-dimethylamino-5-naphthol, 1-acetylamino - 5 - naphthol, 1 - acetylamino-7-naphthol and 2-phenylamino-7-naphthol (all coupled alkaline). Specification 23026/07, [Class 2], is referred to.