GB653695A - Improvements in and relating to the production of alkali cellulose for viscose - Google Patents

Abstract

Cellulose is converted into alkali cellulose for viscose manufacture by treatment with 17-25 per cent aqueous caustic soda solution in the presence of oxygen and an alkali-soluble diazonium hydroxide. The ripening period is thus eliminated or reduced. Benzene diazonium hydroxide is preferred. The process may be carried out as a slurry process by mixing the cellulose, caustic soda and diazonium hydroxide and passing air or oxygen into the slurry, preferably as a finely divided rapid stream whilst mechanically agitating. If desired, cellulose sheets may be steeped in the caustic soda solution containing the diazonium hydroxide in the absence of air or oxygen, pressed and shredded in a Pfleiderer mixer so that air is freely accessible during the shredding. The alkali cellulose is xanthated by the normal procedure when the fluidity of the cellulose has reached the desired figure (determined on cuprammonium solutions). In an example (all parts by weight) 15 parts of wood pulp sheets are steeped in 85 parts of 5.5N caustic soda containing 0.005 per cent benzene diazonium hydroxide and pressed hydraulically to give 45 parts impregnated pulp which is disintegrated in an open Pfleiderer mixer at 25 DEG C. Specifications 13055/14, 14675/14, [both in Class 2 (ii)], 467,500 and 642,843, [Group XXXI], are referred to.