GB534152A - Improvements in and relating to alkali soluble cellulose ethers - Google Patents

Abstract

534,152. Cellulose ethers. REICHEL, F. H. Aug. 24, 1939, No. 24406. [Class 2 (ii)] Cellulose ethers are obtained by treating cellulosic material with alkali solution and then subjecting it to the action of an etherifying agent in the presence of a substantial amount of an anhydrous water-soluble inert salt capable of forming hydrates. with water, continuing the reaction until there are introduced into the cellulose sufficient ether groups to render the cellulose ether soluble at 0‹C. in aqueous sodium hydroxide solutions of 3 per cent. or less alkali concentration but insoluble in water, and thereafter discontinuing the reaction. The amount of water-soluble inert salt may be sufficient to combine with all the water present in forming the lowest hydrate of the salt. The salt used may be sodium sulphate, sulphite, carbonate, tetraborate, acetate, or citrate, or potassium carbonate, citrate. lactate, or tetraborate, or lithium acetate, tetraborate, or citrate. The cellulosic material may be cotton, jute, flax, hemp, straw, wood, sulphite cellulose, cotton linters, regenerated cellulose, de-esterified cellulose esters, hydrocellulose, or cellulose ethers of low degree of substitution. Caustic soda, caustic potash, or a quaternary ammonium hydroxide may be used for making the alkali-cellulose. The etherifying agent may be an alkyl halide or sulphate, sodium ethyl sulphate, a chlorohydrin, an alkylene oxide, or halogenated fatty acid. The anhydrous salt may be added at any stage prior to the etherification step. A further amount of the salt may be added to the washing liquids. In an example, pulp sheets made of cotton linters are soaked in caustic soda solution, drained and pressed. After ageing, the alkali cellulose is mixed with anhydrous sodium sulphate whereby the quantity of free water in the mixture is reduced and the alkali is concentrated. Ethylene oxide is then added and the mixture is kept-in motion by revolving the reaction vessel for several hours. The product is acidified and washed. The reaction is carried out so that the cellulose ether contains at least 2 per cent, of hydroxy-ethyl or its equivalent of another ether group. The product may be mixed with viscose, ammoniacal-copper solutions of cellulose, latex, aqueous artificial dispersions of rubber, gums, resins, casein, gelatine, waxes, fats, and oils. To the dilute alkali solutions of the cellulose ethers there may be added plasticizers, dyes, pigments, wetting agents, waterproofing, or fireproofing agents. The cellulose ethers may be used in the production of filaments, films, tubes, capsules, plastic masses, adhesives, stiffening agents for fabrics, coatings, sizings for textiles and paper, and they may be used as thickening and dispersing agents for pigments and dyes for printing and dyeing textiles and paper. Specification 496,122 is referred to.