GB497407A - The manufacture of azo dyestuffs on the fibre - Google Patents

Abstract

Azo dyestuffs are prepared on the fibre by applying thereto together or successively in either sequence a 2 : 3-hydroxynaphthoic acid arylamide-1-sulphonic acid and a nitrosamine or diazoamino compound derived from an amine having a strongly negative character, and subsequently treating the fibre to reduce the alkalinity of the added materials, whereby the sulphonic group is caused to split off and coupling to take place, the components being so selected that the final dyestuff contains no carboxylic or sulphonic groups. As coupling components, the anilide, o-toluidide, o-anisidide, o - phenetidide and 5 - chlor - 2 - toluidide are specified, and as bases for the production of the nitrosamines or diazoamino compounds, 2 : 5-dichloraniline, 1-trifluoromethyl-3-amino-4 - chlorobenzene, 3 : 5 - bis - trifluoromethylaniline, 1 - trifluoromethyl - 3 - aminobenzene-4-ethylsulphone, 4 - chloro - 2 - nitraniline, and 5-nitro-2-anisidine. In the case of diazoamino compounds, those are preferred which have solubilizing groups in the stabilizers, 2-alkylamino-4 (or -5) sulphobenzoic acids, cyanamide, 1 - carboxy - 2 - amino - 3 : 4 -carbonyl - sulpaminobenzene and 1-carboxy-2-alkylamino-4 (or -5-) benzenesulphamide. In examples: (1) the diazoamino compound from diazotized 2 : 5-dichloraniline and 2-ethylamino-5-sulphobenzoic acid is pasted with the anilide of 1-sulpho-2 : 3-hydroxynaphthoic acid, caustic soda lye, sulphonated castor oil and starch tragacanth thickening, printed on the fibre and the dyestuff developed by steaming in the presence of formic and acetic acid vapours; a deep scarlet shade is obtained; (2) the sodium salt of the nitrosamine of 1-trifluoromethyl-3-aminophenyl - 4 - ethylsulphone and the o-toluidide are similarly pasted and printed; clear gold orange shades are obtained; and (3) the diazoamino compound from diazotized 3 : 5 - bis - trifluormethylaniline and 2 - ethylamino-5-sulphobenzoic acid is dissolved with the o-anisidide, sulphonated castor oil, caustic soda and tragacanth, the fibre is slop-padded with the solution and the dyestuff developed as in (1); reddish-orange shades are obtained.