GB571502A - Improvements in or relating to processes of and apparatus for the production of viscose - Google Patents

Abstract

Viscose is produced by compacting sodium cellulose xanthate and introducing it in the form of thin strip, thin rod or thinly divided pieces into a stirred body of aqueous sodium hydroxide, to which aqueous sodium hydroxide is continuously added and from which viscose is continuously withdrawn. By this process, the xanthate is quickly dissolved and viscose obtained thereby contains a minimum of air bubbles. Sodium cellulose xanthate is fed into the mechanism 10, compacted by screws 12 and 16, and extruded through conduits 18 into dissolving chamber 20 containing an aqueous solution of sodium hydroxide. Rotating knives 28 and 29 serve to cut the xanthate and stir the body of solution. Aqueous sodium <PICT:0571502/IV/1> hydroxide is added continuously to chamber 20 through inlet 22 whilst viscose is continuously withdrawn through outlet 24. In a modification, the compacted xanthate is extruded into the dissolving chamber through a substantially annular slot, whilst a single knife serves to cut the xanthate and stir the solution. In a further modification, the compacted xanthate is extruded through a narrow rectangular slot into the dissolving chamber. The extruded strip of xanthate is readily dissolved in the hydroxide solution, constant stirring of the solution being effected by a rotating propeller. Other forms of compacting mechanism, such as a twin screw press, may be employed. Specification 570,999 is referred to.