GB343986A - Improvements in or relating to the production of cellulose esters and cellulose ester products therefrom - Google Patents

Abstract

Cellulosic material containing more than 8 per cent, and particularly 10 to 30 per cent or more, of water is esterified by the processes of Specifications 309,201, 312,095, 312,096, [all in Class 2 (ii), Cellulose &c.], 342,738, 342,739, and 342,740. The starting material is preferably subjected to a pretreatment, for example, with organic acids, or with hydrohalide acids or halide salts, or mixtures of the said acids and halide salts. Chemical wood pulps may be subjected to an alkaline purifying treatment followed by treatment with organic acids as described in Specification 249,173, [Class 2 (ii), Cellulose &c.]. The cellulosic material is preferably impregnated with the water some time prior to effecting the esterification, or prior to the pretreatment. The water may, however, be introduced during the alkaline treatment referred to above, the materials being washed with water after the treatment and the excess water removed by any suitable means. According to examples, (1) cotton linters are allowed to stand in water overnight and then centrifuged or pressed down to 10-20 per cent of water, after which they are preheated with glacial acetic and esterified; (2) sulphate wood pulp is treated as in Specification 249,173, [Class 2 (ii), Cellulose &c.], with 2-3 per cent caustic soda, washed, treated with acetic acid, again washed and centrifuged or pressed down to 15-25 per cent moisture content. It is then pretreated with glacial acetic acid and finally acetylated. Specifications 263,938 and 312,098, [both in Class 2 (ii), Cellulose &c.], also are referred to. Reference has been directed by the Comptroller to Specifications 309,201, 312,095, and 312,096, [all in Class 2 (ii), Cellulose &c.].