GB478255A - Improvements in or relating to the production of alkali cellulose or other cellulosederivatives, for example, cellulose ethers - Google Patents

Abstract

Alkali cellulose is obtained by mixing cellulose material with an emulsion of caustic soda solution in an inert liquid. The process avoids any contact of the cellulose with solid caustic soda. The process may be carried out by dissolving the alkali in water and then emulsifying the solution by agitating with benzene. Cellulose is then mixed with the emulsion so that fine globules of caustic solution are transferred to the cellulose, and there results a suspension of alkali cellulose in the inert liquid. The alkali cellulose may be used in the production of cellulose derivatives such as cellulose ethers. An etherifying agent may be added to the suspension and the mixture may be heated to effect etherification. In general, the cellulose is added to an emulsion containing the desired amount of alkali and water, but in some cases, part only of the alkali is used in the emulsion, and the remainder is added to the suspension of alkali cellulose in the inert liquid. The process may be carried out in the absence of air. Instead of benzene, there may be used toluene, ether, gasoline, xylene, dibutyl-, dibenzyl-, or dipropyl-ether, or dioxane. Emulsifying assistants such as ethyl, benzyl, butyl, methyl, or glycol cellulose, or cellulose glycollic acid may be used. The cellulose ethers obtained may be used in the production of plastics, safety glass, films, rayon, lacquers, coatings, and electric insulating material. In an example, caustic soda, water, benzene, and a small proportion of ethyl cellulose are mixed and heated until the soda has dissolved in the water and the solution has been emulsified. Granulated high grade wood pulp board is added to the emulsion. The mixture is agitated at raised temperature till the benzene is clear. Ethyl chloride is added and the mixture is heated for several hours. Water is added to the reaction mixture to dissolve salt crystals and form an emulsion, if desired with the aid of turkey red oil or similar assistant. The emulsion is steam distilled and the product is filtered and washed. In other examples, ether is used as the organic diluent and solid caustic soda is added to the suspension of alkali cellulose. In another example, alkali cellulose of low caustic soda content is prepared by the emulsion process, ethylated to a low degree, and then treated with additional solid caustic soda and ethyl chloride. In other examples, benzyl cellulose, and mixed ethers such as glycol ethyl, methyl ethyl, benzyl ethyl, and ethyl butyl cellulose ethers are prepared. In other examples, granulated pulp board is mixed with a wetting agent, "alkanol-M," and then with an emulsion in benzene of a highly concentrated caustic soda solution. Sodium isobutyrate may be used instead of "alkanol." Wetting agents may be added to the reagents or reaction mixtures at any stage of the production of the alkali cellulose. The ratio of caustic alkali to water in the production of alkali cellulose may be 125--200 parts of alkali per 100 parts of water, and there may be 40--300 parts of water per 100 parts of cellulose.