GB538966A - Improvements in a cupro-ammonium process for the production of artificial filaments - Google Patents

Abstract

538,966. Artificial silk. ASAHI-BEMBERG KENSHI KABUSHIKI KAISHA. March 4, 1940, No. 4056. Convention date, June 23. 1939. Drawings to Specification. [Class 2 (ii)] In the manufacture of artificial silk from cellulose dissolved in a cuprammonium solution which is spun into a water bath and the spun filaments treated in an acid bath for completing the coagulation and fixation, the cuprammonium solution is prepared from copper hydroxide recovered from the process ; ammonia is removed from the water bath so that the copper hydroxide is deposited and removed from the bath which is repeatedly used while the acid bath is subjected to electrolysis, metallic copper being produced and sulphuric acid being regenerated so that this bath is also repeatedly used, the copper being electrolysed to form copper hydroxide which is also used for forming the cuprammonium solution. The ammonia from the used water bath may also be used in dissolving the cellulose or it may be recovered as ammonium sulphate. The cuprammonium solution, at the starting of the process, is preferably prepared by the mixture of ammonia and copper hydroxide so that no sulphate radical is produced in the cuprammonium cellulose solution. A small quantity of tartaric acid or glucose may be added to the water bath to prevent the copper hydroxide deposited therein from floating on the bath. When the ammonia is to be recovered from the water bath for use in dissolving the cellulose, acidic ammonium phosphate or borate is employed as an absorbent. The Specification as open to inspection under Sect. 91 comprised the use of the hydrogen, produced in the electrolysis of the copper, as a raw material in the manufacture of ammonia. This subject-matter does not appear in the Specification as accepted.