GB216475A - Manufacture of cellulose solutions - Google Patents

Abstract

Cellulose solutions are prepared by treating cellulose or a cellulose conversion product with an ammonia derivative of carbon dioxide or of an ammonia derivative of a sulphur derivative of carbon dioxide, in the presence of an aqueous alkaline solution; suitable derivatives are urea, thiourea, guanidine, dicyanodiamide, and a -a -dichlorisopropyl-alcohol-carbonic acid ester. Instead of the derivative there may be used a mixture of substances capable of forming it, or of substances which are capable of conversion into the desired derivative. The solutions obtained may be used in the manufacture of artificial silk, &c., films, artificial hair, coatings, dressings, fillings, sizes, plastic masses, and artificial leather. The parent material may be cellulose, products obtained by comminuting cellulose in the presence of water, or by treating cellulose with oxidizing or reducing agents or by heating cellulose alone or in presence of water, glycerine or salts, or products obtained by treating cellulose with hot or cold alkalies with or without subsequent treatment with dilute acids and previous, subsequent or simultaneous treatment with bleaching or oxidizing agents, or cellulose conversion products obtained from solutions of cellulose such as those in cuprammonia zinc salts, or strong acids such as sulphuric acid, phosphoric acid, hydrochloric acid and arsenic acid, or products obtained by treating cellulose with these reagents but not to the point of dissolution, or artificial silk, &c., hydrocelluloses, oxycelluloses, alkali-soluble cellulose derivatives such as those of Specification 177,810. The process may be conducted by dissolving the ammonia derivative of carbon dioxide &c. in alkali solution and then introducing the parent material, or by mixing the parent material and alkali solution and then adding the carbon dioxide derivative. The reaction may be conducted at room temperature or with cooling, for example, to the temperatures below 0 DEG C. preferably at temperatures below 0 DEG and -25 DEG C. or lower, for instance between 0 DEG and -15 DEG C. The strength of the alkali solution may be between 2 per cent and 16 per cent, but a strength of 4-12 per cent is preferred. The proportion of carbon dioxide derivative &c. may be 9-10 per cent of the weight of parent material taken, up to an equal weight or more. The solutions are coagulated by acids, salts, alcohols or even water, or by heat, steam, &c.