GB372828A - Improvements in or relating to the printing of cotton - Google Patents

Abstract

The process of the parent Specification is extended to sulphur dyes, which are converted into pastes suitable for cotton-printing by reduction in the presence of water and glycerine or other water-soluble alcohol and an alkali weaker than an alkali metal hydroxide. Hydrosulphites, glucose, and titanous salts may be employed as reducing agents, and hydrotropic agents may be added to the preparations before, during or after the reduction. In examples (1) the dyestuff obtained by sulphur fusion of carbazole-indophenol is reduced by sodium hydrosulphite in the presence of water, glycerine, and ammonia, with or without the addition of a hydrotropic agent, e.g. the sodium salt of tetrahydronaphthalene-b -sulphonic acid, of benzoic acid, of salicylic acid, of 2-naphthol-1-carboxylic acid or of dimethylsulphanilic acid; other sulphur dyes, e.g. the product obtained by sulphur fusion of ethylcarbazole-indophenol or Hydron navy blue C may be similarly treated, (2) the product of example 1 is pasted with (a) thiodiglycol, caustic soda, calcined sodium carbonate, sodium benzylsulphanilate, sodium hydrosulphite, sodium formaldehyde-sulphoxylate, British gum, and starch or (b) with tragacanth, industrial gum, starch, British gum, glycerine, potassium carbonate, and sodium formaldehyde sulphoxylate; the pastes are then printed on cotton, dried, steamed and developed with potassium chromate and acetic acid, (3) Indocarbon CL is pasted with glycerine, water, and ammonia and reduced with sodium hydrosulphite; the resulting paste may be mixed with a hydrotropic agent, e.g. sodium benzenesulphonate or benzylanilinesulphonate and concentrated, and (4) the product of example 3 is made into a printing paste by addition of thiodiglycol, caustic soda, calcined sodium carbonate, sodium benzylsulphanilate, glucose, sodium formaldehyde-sulphoxylate, British gum, and starch.