GB455253A - Improvements in preparation of cellulose ethers - Google Patents

Abstract

Cellulose ethers are obtained by treatment of cellulose with etherifying agents in presence of quaternary ammonium hydroxides. Trimethyl-ethyl-ammonium hydroxide trimethyl-2-methylallyl ammonium hydroxide trimethylp - chlorobenzyl ammonium hydroxide and similar compounds containing methyl, ethyl, propyl, butyl, amyl, hexyl, benzyl, allyl, and chlor - benzyl, radicals are specified. The reaction may be carried out in solution or suspension. Cotton linters, cotton, sulphite wood pulp, regenerated cellulose such as viscose or cuprammonium rayon, or hydrolyzed cellulose esters may be used as starting material. Degraded cellulose material may also be used. Cellulose may be dissolved in the quaternary ammonium base and then treated with etherifying agent. Caustic soda may be added to the solution of cellulose in the organic base prior to etherification. The etherifying agent may be an alkyl, aralkyl, hydroxy alkyl, or alkylene ester of an inorganic acid such as ethyl chloride, bromide, iodide, or sulphate, or ethylene chlorhydrin, or it may be an ethylene oxide. In an example, wood pulp is dissolved in trimethyl-benzyl ammonium hydroxide in a heated dough mixer. Caustic soda solution is added and then dimethyl sulphate. After several hours the reaction mass is diluted with water and neutralized with acetic acid so as to precipitate methyl cellulose. Dilute sulphuric acid may be used for neutralization. In other examples ethyl bromide, diethyl sulphate, benzyl chloride, 2-methyl-allyl chloride, and ethylene oxide are used as etherifying agents. The cellulose ethers in their primary solutions may be further etherified and mixed ethers such as ethyl benzyl cellulose may be obtained. Ethylene oxide may be used in gaseous form and passed into a solution of cellulose in trimethyl benzyl ammonium hydroxide. In another example, bleached sulphite wood pulp is dissolved in an aqueous solution of trimethyl benzyl ammonium hydroxide and then 2-methyl allyl chloride is added. The cellulose methylallyl ether which separates is filtered and washed. It is soluble in strong acetic acid solution. The cellulose ethers obtained may be used for the manufacture of filaments and films. Cellulose and a cellulose ether obtained by the process may be dissolved in an aqueous solution of a quaternary ammonium hydroxide and the solution may be used for the production of filaments or films.