GB549392A - Improvements in or relating to the production of cellulose derivatives - Google Patents

Abstract

549,392. Cellulose derivatives ; treating filaments, foils &c. ; di-cyanamides. DREYFUS, H. May 16, 1941, No. 6327. [Classes 2 (ii) and 2 (iii)] Cellulose derivatives are obtained by reacting cellulosic materials with an organic compound containing two cyanamide radicals. The cellulosic material may be cotton linters, chemical wood pulp, cotton yarns, regenerated cellulose material obtained by the viscose or cuprammonium process or by the saponification of cellulose esters, or material made of an organic derivative of cellulose containing free hydroxy groups. The process is applicable to the treatment of yarns, foils, and other formed articles. The safe ironing temperature and melting point of cellulose ester or ether materials is raised by the treatment. Yarns of high tenacity, in hank or fabric form, obtained by stretching acetone-soluble cellulose acetate yarns in wet steam or hot water under pressure, or yarns of regenerated cellulose made by saponification of such stretched yarns, may be subjected to the di-cyanamide treatment. The cyanamide used may be ethylene or hexamethylene di-cyanamide, ##<SP>1</SP>-di-cyanamido-diethyl ether, ##<SP>1</SP>-di-cyanamido-diethyl sulphide, or a di-(#-cyanamido-ethyl) benzene. The reaction may be effected by heating the materials in a solution of the di-cyanamide, e.g. at 50- 150‹C. The reaction may take place with the initial material in solution. Cellulose acetate in fibrous or powder form may be refluxed with a solution of a di-cyanamide in acetone, and on completion of the reaction, the product may be precipitated by the addition of a non-solvent or separated from the reaction mixture if it has become insoluble therein. Formed articles such as filaments and foils may be treated in a, reaction medium which does not deleteriously affect their physical condition. They may be treated with a solution of a di-cyanamide in alcohol, acetone, or chloroform, and the cyanamide may be concentrated on the materials by evaporation. The di-cyanamides may be obtained by hydrolysing the correspon ing di-thioureas which may be obtained by reacting diamines with thiocyanates particularly alkali thiocyanates. The di-thioureas may be hydrolysed by caustic soda or other strong base and this reaction is facilitated by the presence of a lead compound such as lead acetate or lead oxide. The Provisional Specification describes also the treatment of cellulosic materials with monoalkyl cyanamides in which the alkyl groups contain a large number of carbon atoms.