GB670672A - Mixed cellulose ether and preparation thereof - Google Patents

Abstract

A mixed carboxyalkyl hydroxyalkyl cellulose ether is obtained by first introducing into the cellulose at least 0.05 hydroxyalkyl groups per anhydroglucose unit by reacting cellulose with a hydroxyalkylating agent, and subsequently but without separating the hydroxyalkyl cellulose thus formed from the reaction mixture, introducing at least 0.05 carboxyalkyl groups per anhydroglucose unit by reacting with a carboxyalkylating agent, the total amount of hydroxyalkyl and carboxyalkyl substituent groups thus introduced being at least 0.5 per anhydroglucose unit so as to produce a water-soluble carboxyalkyl hydroxyalkyl cellulose ether. The reaction may be carried out in the presence of an organic liquid which maintains the cellulose ether in a solid undissolved state throughout the treatment. The liquid used may be an aliphatic alcohol containing 3 or 4 carbon atoms, dioxane, tetrahydrofuran, or the diethyl ether of ethylene glycol. Isopropanol or tertiary butyl alcohol may be used. The cellulose ethers containing 0.15-0.75 hydroxyethyl groups and 0.2-0.9 carboxymethyl groups in the molecule are soluble in aqueous solutions having a pH of 0.2 as well as being soluble in water. They are not precipitated from a 1 per cent water solution with an equal weight of 10 per cent barium chloride or zinc nitrate solution. In an example, cotton linters are mixed with isopropanol and then with caustic soda solution. Ethylene oxide in isopropanol is then added and the temperature is slowly raised to 69 DEG C. for 1 hour and then maintained at 68-73 DEG C. for 4 hours. There is then added to the reaction mixture a solution of monochloracetic acid in isopropanol. The mixture is stirred for 2 hours and then allowed to cool and stand at room temperature for 15 hours. The cellulose ether obtained is washed with methanol, neutralized, dehydrated with methanol, and dried. An alkylene chlorhydrin may be used instead of an alkylene oxide for the hydroxy alkylation. Instead of a chlorinated lower fatty acid, there may be used a vinyl compound containing a carboxyl group or a group convertible thereto, e.g. an acrylic ester. The cellulose ethers obtained are particularly suitable for use in making detergent compositions, e.g. a carboxymethyl hydroxyethyl cellulose ether may be mixed in equal proportions with an alkylaryl sulphonate. They may also be used as general thickening agents, pigment - dispersing materials, emulsion stabilizers, printing paste additives, adhesives, binders, textile finishing agents, film-forming agents, creaming agents, and thickening agents for pharmaceutical preparations. They may be used, if desired, in the form of their metallic or amine salts.ALSO:A mixed carboxyalkyl hydroxyalkyl cellulose ether, obtained by a two-stage etherification process (see Group IVa) and having at least 0,05 hydroxyalkyl groups and at least 0,05 carboxyalkyl groups per anhydroglucose unit of the cellulose, is used in the production of detergent compositions. In an example, a carboxymethyl hydroxyethyl cellulose ether is mixed in equal proportions with an alkyl aryl sulphonate.