GB635310A - Improvements in colouring cellulose ester or ether textile materials - Google Patents

Abstract

Textile materials of cellulose esters or ethers are mechanically impregnated with an aqueous suspension of an indigoid vat dyestuff, then impregnated with an aqueous solution of a formaldehyde sulphoxylate made alkaline with a hydroxy aliphatic amine, steamed to reduce the dyestuff to the leuco form and the latter is finally oxidized back to the parent dyestuff on the fibre. The dyestuff is made up into an aqueous suspension, preferably with a dispersing agent of the alkyl sulphate type, and applied to the material by padding or other mechanical means. The material is then preferably dried, and treated with aqueous sulphoxylate (e.g. sodium formaldehyde sulphoxylate in 2-15 per cent w/w) containing the hydroxy amine (2-15 per cent w/w); this treatment may also be by padding. Diethanolamine is the preferred amine, but mono-or tri-ethanolamine may also be used, or triisopropanolamine. After steaming to reduce the dyestuff to the leuco form and fix the latter on the fibre, re-oxidation may be effected with an acid oxidizing agent such as sodium dichromate and acetic acid; sodium perborate or hydrogen peroxide may be used instead. The material is then soaped, rinsed, dried and finished in the usual way. The dyeings are stated to be fast to light, gas, rubbing and washing. The process is applicable to fabrics, yarn or staple fibre of cellulose acetate or other ester or ether. Suitable dyestuffs are mentioned. An example is given of the treatment of cellulose acetate according to the process of the invention.