GB324680A - Process for the preparation of dyed effect threads - Google Patents

Abstract

324,680. Chemical Works, formerly Sandoz. July 31, 1928. Addition to 280,493. Cellulose acetates.-Dyed effect threads, fast to cross-dyeing, are obtained by subjecting to theacetylation treatments of Specifications 280,493, 314,913, and 323,500, vegetable fibres dyed with dyestuffs of the azo, polyazo, stilbene, sulphur, or vat series which are fast to acids, are insoluble in acid or anhydride, and contains no free amino group capable of acetylation. Azo or poly. azo dyestuffs which contain a diazotizable amino group may be diazotized on the fibre and coupled with a component prior to the acetylation. Thefastness, especially to washing and water, of direct dyes on cotton is enhanced by the acetylation. The following examples are specified : (1) Cotton-yarn, dyed with Chloramineyellow FF, is acetylated by treatment for 20 hrs. at 35‹ C. in a bath containing 14 per cent of acetic anhydride, 80 per cent of glacial acetic acid, and 6 per cent of zinc chloride; the yellow threads so obtained do not stain interwoven cotton in washing or in boiling for 1 hour. (2) Mercerized cotton yarn, dyed with Chlorantine fast red 7BL, is immersed in warm 99 per cent glacial acetic acid, centrifuged, and acetylated by treatment at 30‹ C. in a bath containing 20 percent of acetic anhydride, 75 per cent of glacial acetic acid, and 5 per cent of zinc chloride until a sample after washing and drying is no longer dyed violet with Chloramine sky blue FF; the red threads so obtained, after being interwoven with other threads, can be washed, boiled or treated with chlorine without alteration of shade. (3) An acetylating mixture at 80‹ C, containing 10 per cent of acetic anhydride, 87 per cent of glacial acetic acid, and 3 per cent of zinc chloride is pumped for 8 hrs. through cops which have been dyed with Thional black T and dried. and the cops are then hydroextracted, washed, and dried; the black threads so obtained retain their deep black tint in cross-dyeing with direct dyes. (4) 100 parts of kier-boiled yarn, dyed with Indanthrene blue CCD, are aeetylated by treatment at 40‹ C. in a mixture consisting of 250 parts of acetic anhydride, 900 parts of glacial acetic acid, and 100 parts of phosphoric acid until the colour of a washed and dried sample is no longer turned green with Chloramine yellow FF.