GB470926A - Improvements in or relating to the production of cellulose ethers - Google Patents

Abstract

Alkyl ethers of cellulose soluble in caustic alkali and containing not more than one molecular proportion of alkyl group per C6H10O5 unit, are prepared by treating cellulose with an aqueous caustic alkali solution not exceeding 50 per cent concentration, and either previously, simultaneously or subsequently treating the material with an aqueous solution of an alkali metal lower alkyl salt of sulphuric acid, in particular, sodium methyl or ethyl sulphate and sodium methoxy or ethoxy ethyl sulphate. Generally the cellulose is in the form of wood pulp sheets; as alternatives, cotton linters in sheet form may be employed, or there may be used wood cellulose in bulk, or material treated may be cotton broadcloth in which case the cloth acquires a permanently sized effect and an increased affinity for cotton dyes. Preferably the alkylating agent is added to the caustic alkali lye used for steeping; after impregnation and pressing, in some cases followed by disintegration, the materials may be allowed to age for some days preferably in an inert atmosphere, reaction occurring during the ageing. Caustic alkali lye of 18 per cent strength is preferred; wetting agents such as mercerizing assistants may be added to the steeping solutions; and the temperature of reaction may be varied from 0 to 150 DEG C. The alkylated products are washed with water, and may be dissolved in dilute caustic soda solution at room temperature or below to give clear solutions suitable for the manufacture of films; typical products contain 2--3,45--5 per cent methoxy or ethoxy groups. Specification 469,901 is referred to.