Improvements in the manufacture of artificial silk

Abstract

Abstract In the manufacture of artificial silk, threads or filaments spun from cellulose derivatives or a cuprammonium solution of cellulose are first treated to remove beta and gamma celluloses or cellulose derivatives, then treated with a swelling or plasticizing agent and stretched, the swelling or plasticizing agent being then removed. The purifying treatment is applied at any stage during or after formation of the filaments but before final stretching. Preliminary stretching may be applied during formation or coagulation of the filaments. In examples: (1) Cellulosic threads prepared from viscose, cuprammonium or cellulose nitrate are treated at 50-60 DEG C. with a 6-10 per cent solution of caustic soda containing a neutral salt e.g. 6-12 per cent of Glauber's salt; after washing free from soluble products, the threads are treated with a suitable swelling agent e.g. zinc chloride, thiocyanates, sulphuric, hydrochloric or nitric acids, or ammoniacal copper solution, and stretched; while under stretch, the swelling agent is removed. (2) Threads from an acetone-soluble cellulose acetate are extracted with aqueous acetone of 50-80 per cent strength to remove beta and gamma cellulose acetates and are then swollen with known swelling agents and stretched, the swelling agent being removed while the threads are under stretch. Suitable swelling agents comprise dilute acetone or acetic acid of less than 50 per cent strength, lactic acid, zinc chloride, thiocyanates, sulphuric and phosphoric acids, and ammoniacal copper and nickel solutions. The following matters are disclaimed-treatment of artificial silk threads with caustic alkali followed by removal of the alkali; treating filaments with alkali and stretching; the production of viscose and cuprammonium solutions from purified cellulose; purification of formed threads by treatment with agents capable of dissolving out the beta and gamma celluloses or other soluble products; and swelling or plasticizing followed by stretching and subsequent removal of the swelling or plasticizing agent. Specifications 229,678, 271,517, and 319,291, [all in Class 2 (ii), Cellulose &c.], are referred to.

Inventors

No inventors recorded.

Bibliographic Details