GB475966A - Dyeing of furs, pelts and hair and new dyestuffs therefor - Google Patents

Abstract

Monoazo dyes; acid wool and mordant dyes, dyeing with.--Furs, pelts and hair are dyed in level shades, fast to light and rubbing, with monoazo dyes obtained by coupling diazotized picramic acid with an aminonaphthol free from sulphonic or carboxylic groups or an N-substituted derivative thereof. The manufacture of the dyestuffs having as coupling component an N - hydroxyalkylaminonaphthol is also claimed. The materials are, preferably, subjected to a preliminary degreasing and purification treatment with alkaline agents, such as soda ash, ammonia, lime or caustic soda and, after removing residual alkali, to a chrome tanning treatment, e.g. with chrome alum, an alkali bichromate or basic chromium sulphate. Any resulting acidity is then neutralized with sodium bicarbonate to a pH of 6 to 7 before the dyeing. The materials may be further pre-treated with hypochlorites or phosphates to increase the dyeing capacity of the hairy portions and promote even dyeing. Examples are given of the manufacture of the dyestuffs having as coupling component (coupled alkaline) 1-(b -hydroxyethyl)amino-5-naphthol (cf. Specification 436,805), 1-dimethylamino-5-naphthol and 1-acetylamino-5-naphthol and (coupled acid) 1-b -hydroxyethyl)amino-5-naphthol. In examples of the dyeing process: (1) chrometanned long haired white rabbit fur is entered into an aqueous bath at 40 DEG C. containing the dyestuff, picramic acid --> (alkaline) 1 : 5-aminonaphthol, and the temperature is raised during 20 minutes to 75 DEG C. and so maintained for 30 minutes, acetic acid is added, dyeing is continued for 30 minutes, formic acid is added and the dyeing continued for 40 minutes, whereupon the fur is dried and drummed in sawdust to obtain a nigger brown dyeing; (2) chrome-tanned shorn white rabbit fur is entered into an aqueous bath at 40 DEG C. containing the dyestuff, picramic acid ---> (alkaline) 1-(b -hydroxyethyl)amino-5-naphthol, and the temperature is raised during 20 minutes to 55--60 DEG C. and so maintained with addition as in (1) of acetic and formic acids, whereupon the fur is dried and drummed as in (1) to obtain a reddish nigger brown dyeing, fast to rubbing. A table is also given showing the shades obtainable with the dyestuffs from the following additional coupling components, viz.: (coupled alkaline) 1 : 7-, 2 : 5- and 2 : 7-aminonaphthols, 1 - acetylamino - 7 - naphthol, 1-(b hydroxyethyl)amino-7-naphthol and 2-phenylamino-7-naphthol and (coupled acid) 1 : 5-, 1 : 6-, 1 : 7- and 2 : 7-aminonaphthols, and 1-(b -hydroxyethyl)amino - 6- and -7 - naphthols. Specification 10716/15, [Class 2 (iii)], also is referred to. 1-(b -Hydroxyethyl)amino-6- and -7-naphthols are obtained by condensing 1 : 6- and 1 : 7-aminonaphthols respectively with ethylene chlorhydrin in presence of an acid binding agent, e.g. chalk or sodium acetate.