GB381943A - Improvements in processes for dyeing materials made from cellulose esters or ethers - Google Patents

Abstract

Cellulose esters or ethers, dyeing; azo dyes, forming on the material; azo dyes; triarylmethane dyes.--Artificial materials made from solutions of cellulose esters or ethers or made by acidylating products obtained by precipitation of cellulose from solution are washed and thereafter dyed by treatment in a dyebath while they are still in a swollen condition brought about in the course of their production. The process is applicable to artificial silk, horsehair, ribbons, films, capsules &c. The following examples are specified: (1) Wood pulp is converted into viscose in the usual manner, the ripened solution is spun, the spun material is acetylated as described in example 1 of Specification 367,312, washed successively with glacial acetic acid, acetic acid and water and dyed in a bath containing sodium sulphate and the dyestuff p-aminosalicylic acid --> 1-naphthylamine --> (alkaline) 2 : 8 : 6-aminonaphtholsulphonic acid to obtain a fast black. (2) The material obtained by spinning ripened viscose and treating the spun product with butyric anhydride, as described in Example 2 of Specification 367,312, is washed as above and dyed with the dyestuff 1-aminobenzene-2-p-tolylsulphone - 5 - sulphonic acid --> ethyl-2-naphthylamine to obtain a red, fast to washing. (3) An acetone solution of acetylcellulose is spun wet using a precipitating bath containing ammonium nitrate and ammonium sulphocyanide and the resulting threads are washed with water and dyed with the sulphonated oxidized condensation product from 4 : 4<1> - tetramethyldiaminobenzhydrol and benzyl-1-naphthylamine to obtain a vivid blue, fast to washing. (4) Artificial silk yarn obtained as in (1) is treated for \ba1/2\be hr. at room temperature in an aqueous solution of 1-naphthol-4-phenylketone containing no excess of alkali, washed, and developed with the diazotized phenyl ether of 4-chloro-2-aminophenol to obtain an intense fast red dyeing. (5) A shrinkable film capsule made by precipitation with water from a formic acid solution of a cellulose formate-cellulose acetate mixture is washed till free from acid and dyed a vivid fast red in a bath containing sodium sulphate and the dyestuff 4-aminoazobenzene-4<1>-sulphonic acid --> (alkaline) benzoyl-2 : 5 : 7-aminonaphtholsulphonic acid. (6) An acetyl-cellulose solution, made by acetylation as described in Example 7 of Specification 359,249 of a solution of cellulose in ethylpyridinium chloride and pyridine, is spun in 70 per cent alcohol and the threads are washed with water and dyed an intense red in a bath containing the dyestuff 3 : 3-diamino-4 : 4<1>-dimethyldiphenylmethame \sQ 1-naphthol - 4 - sulphonic acid (2 mols.).