GB323521A - Improvements in or relating to the treatment of films, threads, fabrics and like materials made from or containing cellulose esters and ethers - Google Patents

Abstract

323,521. Dreyfus, H. July 24, 1928. Drawings to Specification. Yarns, treating with liquids.-Artificial filaments, threads, and the like composed of organic substitution derivatives of cellulose for example, organic acid esters of cellulose or cellulose ethers, or mixed threads and the like containing such artificial filaments or threads, are impregnated with cellulose by treating them with a solution of cellulose or of a celluose compound which is subsequenty decomposed to cellulose. The materials may, for example, be treated with solutions of cellulose, for instance in aqueous thiocyanates, such as calcium or ammonium thiocyanates, or in zinc chloride or ammoniacal copper solutions and then subjected to any suitable treatment, for example with water or dilute acids, in order to precipitate the cellulose. Alternatively, the materials may be treated with solutions of viscose and then with solutions of acids, acid salts or other substances to precipitate cellulose or they may be treated with a solution of nitrocellulose in a non-solvent for the organic substitution derivative of cellulose, for example in ether-alcohol solution, and thereafter subjected to saponification, for example with aqueous solutions of alkalies, or denitration, for example with dilute ammoniacal solutions of sulphydrates, such as commercial ammonium sulphide or sodium or magnesium sulphydrate in presence of an ammonium salt, to convert the nitrocellulose into cellulose. The materials may be treated simply by soaking or by passing them continuously through baths. In the case of artificial filaments or threads, the treatment mav be carried out continuously with the production of the materials by the dry or wet methods. When a solution of nitrocellulose in a volatile solvent is employed for the continuous impregnation, the threads or the like may be passed through an evaporative chamber instead of a coagulation bath in order to fix the nitrocellulose thereon. In examples, a cellulose acetate film is immersed in a bath composed of a saturated solution of cellulose in an aqueous solution of zinc chloride and thereafter washed with dilute hydrochloric acid and water; a cellulose acetate warp is run slowly from a beam through a bath containing a solution of viscose. combs, reeds or the like being provided at each end of the bath to prevent contact between adjacent threads, and then into a precipitation bath comprising for example a solution of sodium bisulphate and the threads are wound on a perforated warp beam, whereon they are washed with water until free from salts and sulphuric acid and then dried ; cellulose acetate silk is impregnated with cellulose by applying a solution of nitrocellulose continuously with the dry spinning of the artificial silk and then denitrating. Specification 295,582. [Class 15 (ii), Dyeing, Processes &c. for], is referred to.