GB637133A - Improvements in the production of alkali cellulose and cellulose derivatives made therefrom - Google Patents

Abstract

Alkali cellulose is produced by mixing, without grinding, cellulose of packing density (as defined in the Specification) above 10 lb./cu.ft. with solid caustic alkali. The packing density is preferably between 10 and 35 lb./cu.ft., and especially between 15 and 30 lb. cu.ft. The cellulose may be produced from sheets of purified wood pulp so that the product has at least one dimension less than 0.2 in. and preferably less than about 0.1 in., for example between about 0.02 in. and 0.075 in. The cellulose is mixed with dry flake or powdered caustic alkali, preferably in the proportion of 8-35 molecular proportions of alkali for each glucose residue in the cellulose. An organic liquid such as an ether-alcohol may be added to the mixture, which may be etherified with, for example, methyl or ethyl chloride or chloracetic acid. In a modification, the caustic soda may be in the form of an aqueous solution of concentration at least 70 per cent, or a saturated solution containing some solid. In one example, sheets of purified wood pulp were broken up and granulated in a mixer to give a product of packing density 26 lb./cu.ft. in which the particles were less than 0.1 in. across. This cellulose was mixed with about 2.5 times its weight of dry powdered caustic soda and 20 per cent (of the weight of the cellulose) of monomethyl glycol was added. The mixture was passed to a mixer, then transferred to an autoclave and etherified with ethyl chloride to give an ethyl cellulose of ethoxy content about 52 per cent. Specification 637,134 is referred to.