GB231807A - Manufacture of cellulose derivatives - Google Patents

Abstract

Cellulose derivatives soluble in aqueous alkalies but insoluble in water and the usual organic solvents, are obtained by acting on cellulose or an alkali-insoluble cellulose conversion product with a halohydrin of a polyalcohol or a derivative or internal anhydride of such halohydrin, in the presence of an alkali solution of not more than 30 per cent strength, preferably up to 25 per cent strength. Halohydrins of glycerol or glycol such as a -monochlorhydrin and ethylene chlorhydrin are suitable; the monohalohydrins are preferred. According as the alkali solution is weaker, so a larger excess of halohydrin is permissible. The derivatives so prepared are distinguished by their inertness, their resistance towards alkalies, their durability, and the flexibility and the transparency of the products made from them; and they are suitable for the manufacture of artificial threads, films, plastic compositions, coatings, finishes for textiles, sizes, thickening-agents for textile printing, and fixing-agents for pigments. The treatment of the cellulose with alkali and halohydrin may be carried out simultaneously or successively in either order; the cellulose may be impregnated or kneaded with the aqueous or alcoholic solution of caustic alkali, and, if necessary, the excess of solution removed; the halohydrin is added in an undiluted state or diluted with water, ether, alcohol, etc.; the reaction proceeds without extraneous supply of heat, although the alkali-cellulose may be heated prior to or during the addition of the halohydrin; contact substances such as copper, silver, iron, or benzoyl superoxide may be added. The reaction mixture may be worked up into technical products after the addition of water or caustic alkali solution in order to effect solution of the cellulose derivative; or the latter may first be isolated by washing with water or aqueous alcohol, with or without previous neutralization or acidification. When working up the products it is convenient to effect fixation by dilute acid or any other precipitating-bath used for viscose. Specifications 166,767, 177,810, 203,346 and 203,347 are referred to. The Specification as open to inspection under Sect. 91 (3) (a) includes the use in the above process of alkali of a strength up to 50 per cent. This subject-matter does not appear in the Specification as accepted.