GB506793A - Improvements in or relating to the dyeing of textile materials comprising cellulose or its derivatives - Google Patents

Abstract

506,793. Dyeing textiles; artificial silk ; resinous condensation products. COURTAULDS, Ltd., and TALLIS, E. E. Nov. 30, 1937, No. 33086. [Classes 2 (ii), 2(iii),and 15 (ii)] The dyeing properties of textile materials, comprising cellulose or its derivatives which do not contain protein substances or their derivatives or basic amino or imino groups, e.g. cotton, rayon, linen &c. are improved by incorporating therein a product obtained by causing cyanamide and formaldehyde to react under acid or neutral conditions. Alternatively, the materials are impregnated with a solution' obtained by the admixture of solutions of cyanamide and formaldehyde, maintained slightlyÀ acid, and are subsequently dried and heated to cause condensation. Alternatively, the condensation products may be incorporated in the solutions from which artificial threads are produced. In examples: (1) crude calcium cyanamide is extracted with water, filtered, neutralized with strong sulphuric acid, the calcium sulphate filtered off and formaldehyde solution, ammonium thiocyanate and water added to the filtrate; viscose staple fibre is steeped in this solution, centrifuged, dried and heated for twenty minutes at 140‹ C., whereupon it is dyed with Azo-geranine 2GS. in a bath containing sulphuric acid; (2) a solution of formaldehyde and cyanamide is heated until a white precipitate is formed; this is filtered off, washed and dried and then dispersed in acetone and added to a cellulose acetate spinning solution ; the cellulose acetate yarn obtained is dyed with Azo-geranine 2 G.S. or Erio fast cyanine S in a bath containing formic acid ; (3) viscose is impregnated with a solution containing cyanamide, formalin and ammonium thiocyanate, hydroextracted, dried, heated at 150‹ C. for 5 minutes and dyed with Coomassie red P.G.S. or Indigosol blue I.B.C. ; (4) staple fibre is impregnated with a solution of cyanainide and formaldehyde which has been heated, rapidly cooled and diluted, and is hydroextracted, dried, heated to 100‹ C. for an hour and dyed with Azo-geranine 2 G.S. in a bath containing formic acid. Intensifiers or other useful compounds known to increase the affinity of the material for certain direct dyes may be added to'the treatment solutions ; when such compounds are basic, e.g. triothylamine, they are neutralized before being added. The process increases the affinity of the material for substantive, sulphur, vat, azoic, basic and acid dyes and for cellulose acetate &c. dyes. Specifications 319,822, [Class 2 (iii)]. and 484,901 are referred to