GB429350A - Process for the manufacture of sulphur-dyestuff preparations - Google Patents

Abstract

Dry or highly concentrated reduced sulphur dyestuff preparations containing sufficient sodium sulphide for dyeing to be effected without further addition to the dyebath are obtained by reducing sulphur dyestuffs with alkali sulphide solution of at least 30 per cent strength and in quantity sufficient for the reduction and the dyeing process, and concentrating at a temperature below the boiling point of the mixture. An alkali hydrosulphide may wholly or in part replace the alkali sulphide. When sulphurized baked dyestuffs are used, the crude melt is leached with caustic alkali and alkali sulphide added to the resulting solution so that there is present at least 30 parts of sodium sulphide for every 70 parts of water and also sufficient sodium sulphide for the dyeing process. Concentration of the dyestuff is then effected at a temperature below the boiling point. In examples, reduced preparations containing sodium sulphide are prepared from the following: sulphur dyestuffs obtained from the leuco indophenol 3 - methyl - 4 - amino - 4<1> - oxydiphenylamine and the condensation product of diphenylamine-2-carboxylic acid and nitrosophenol by treating with polysulphide, the dyestuff obtained according to Specification 7332/00, [Class 2], from trinitrophenol, the dyestuff obtained according to Specification 11771/02, [Class 2], from m-toluylenediamine and the dyestuff obtained according to Specification 3279/07, [Class 2], by melting m-toluylenediamine and p-phenylenediamine with sulphur.