GB456841A - Improved process for the production of cellulose xanthate solutions - Google Patents

Abstract

Viscose is manufactured in a continuous series of operations all carried out at 12--18 DEG C., wherein cellulose pulp is alkalized in a sodium hydroxide solution of sufficient concentration and quantity to effect complete conversion to alkali cellulose, this quantity being about 13 parts by weight per 4 parts of a -cellulose when the concentration of the solution is 19 per cent, and being varied proportionally for other concentrations, and wherein the alkali cellulose is xanthated, dissolved in dilute alkali, and filtered ready for immediate precipitation. The process avoids the usual steps of ageing. Preferably, a high p grade a -cellulose material is used, but poorer quality material may be used if desired. In an example, cellulose pulp is formed into crumbs and mixed in a closed container with the requisite quantity of caustic soda for 20--40 minutes, the time being less for high viscosity pulp than for pulp of low viscosity. The alkali cellulose without being ripened is mixed with carbon disulphide which is sprayed into the container during the mixing. The cellulose xanthate is dissolved in dilute caustic soda preferably containing a small amount of sodium sulphite. If desired, the xanthating and dissolving processes may be combined to one operation. The temperature may be kept below 18 DEG C. by circulation of water, brine, or ammonia through the jacket of the mixing tank. Sodium oleate or stearate may be added to the viscose to reduce surface tension. The viscose is filtered through one or more presses and pumped to containers. It is then ready to be cast or extruded to form artificial filaments, sheets, or foils.