GB430222A - Improvements relating to the manufacture of azo dyestuffs - Google Patents

Abstract

Azo dyes are formed on textile material or on a substratum by applying mixtures of aromatic nitramines, nitrites and coupling components and developing the colour by treating first with an acid and thereon with an aqueous solution of an acid-binding agent. Dyeing assistants, wetting agents, solvents, &c. and water soluble salts may also be incorporated in the mixtures. The nitraminates or nitramines and free alkalies may be used. In examples: (1) cotton is printed with a paste containing o-nitrophenylnitraminate of sodium, caustic soda, 2 : 3-oxynaphthoic acid anilide, sodium nitrite, sodium phosphate, ethanol, formaldehyde, starch tragacanth, glycol and pyridine, dried, passed through sulphuric acid and then through a bath containing sodium acetate; (2) textile goods are similarly printed with a paste containing 1-methoxy-4-nitro-6-nitraminate of sodium, sodium nitrite and the m-nitranilide or 4-chloro-2-methyl-1-anilide of 2 : 3-oxynaphthoic acid and the colour developed first with oxalic acid and then with sodium carbonate; (3) cotton is printed with a thickened mixture of 1-methyl or 1-chlor-3-nitro - 4 - phenylnitraminate of sodium, 2-hydroxy - 3 - naphthoylaniline, sodium nitrite and caustic soda and the colour developed first with sulphuric acid containing sodium isopropylnaphthalene sulphonate and then with sodium carbonate. Other nitramines, coupling components, alkalies, water-soluble salts, acids and dyeing assistants are mentioned in the Specification.