GB331612A - A process for improving the dyeing properties of viscose silk - Google Patents

Abstract

331,612. Johnson, J. Y., (I. G. Farbenindustrie. Akt.-Ges.). April 22, 1929. Yarns &c., treating with liquids.-The lustre and dyeing properties of viscose silk are improved by treating freshly finished viscose silk of any kind while still in the wet state with ammoniacal copper oxide solutions free from caustic alkali, and containing up to 0.3 per cent of copper, until a small percentage of the dry weight of the viscose silk has dissolved. In the case of viscose silk having orientation of the cellulose micellae the process may be carried out after the initial drying. The threads may be treated on spools directly after spinning, stretching, and acid treatment, with the ammoniacal copper oxide solution which may contain other ingredients such as dissolved cellulose but no free caustic alkali. The strength of the copper solution is varied within the limits claimed according to the particular viscose silk to be treated and adjusted so that only a few per cent of the silk are dissolved. The concentration is preferably chosen so that the treatment does not exceed 1 hour. The threads are afterwards treated with dilute acid. The treated viscose silk has a silky lustre, is microscopically roughened so that slipping of the threads is reduced, and can be dyed more evenly and in stronger shades than untreated viscose silk. In examples " Agfa Seide " or " Agfa Travis " silk is washed immediately after spinning and treated before or after desulphurizing, on spools at room temperature with ammoniacal copper oxide solution containing 0.2 to 0.3 per cent of copper and 4 to 6 per cent of ammonia for half an hour. The spools are washed with dilute sulphuric acid, and with water. In other examples viscose silk prepared according to Specification 274,521, [Class 2 (ii), Cellulose &c.], is treated for 8 minutes with a solution containing 1.5 grams of copper and 50 grams of ammonia per litre, or for 1 minute with a solution containing 3 grams of copper and 50 grams of ammonia per litre. The silk is washed with dilute sulphuric acid and with water. In the Provisional Specification an example is given in which the strength of the ammoniacal copper oxide exceeds 0.3 per cent of copper.