GB410118A - Manufacture of organic esters of cellulose and its derivatives - Google Patents

Abstract

Cellulose phthalate is prepared by treating undissolved cellulose with phthalic anhydride in presence of an organic tertiary base and continuing the phthalylation until a dope is formed; one carboxyl group esterifying the cellulose, and the other being combined with the organic base, from which it can later be freed by treating the product with an acid. Cellulose modified or pretreated in any way so as to increase its reactivity, regenerated cellulose or a cellulose ester or ether containing free hydroxyl, for example, a cellulose acetate or a cellulose ethyl ether may be used as starting material. Pyridine, quinoline, or other saltforming bases of the same group, or bases such as the dialkylanilines, for example, dimethyl aniline, the hexalhydro-dialkylanilines, dimethyl n - hexylamine are suitable organic bases. A solvent such as benzene, tetrachloroethane, or ethylene chloride may be added to the reaction bath. The reaction temperature is preferably below 95 DEG C. When the required degree of esterification is attained, the reaction mass is precipitated in a non-solvent for the ester. The products obtained are generally soluble in water containing a small amount of pyridine, in pyridine-benzene pyridine-tetrachlorethane, pyridine-ethylene chloride and similar mixtures, and in other inert organic solvents. From solutions of the esters in suitable solvents transparent sheets or skins may be formed, plasticisers such as an alkyl phthalate, triphenyl or tricresyl phosphate, a p - alkyloxalkyl phthalate, or tributyl phosphate. The esters may also be used in adhesives, for laminated glass, lacquers, artificial silk, and moulded products, either alone or mixed with a plasticiser and other compatible addition products. Examples are given. U.S.A. Specification 1,704,306 is referred to.ALSO:Cellulose phthalates are employed in the manufacture of moulded products &c. Phthalic acid derivatives of cellulose esters such as the acetate or of cellulose ethers such as the ethyl ether which still contain esterifiable hydroxyl groups are included. These esters are generally soluble in pyridine and in mixtures of pyridine with suitable organic solvents; from the solutions transparent sheets or skins may be formed, plasticisers such as an alkyl phthalate, triphenyl or tricresyl phosphate, a b -alkyloxyalkyl phtholate, or tributyl phosphate being added. When used in the manufacture of moulded products, plasticisers and other compatible addition products may or may not be added. U.S.A. Specification 1,704,306 is referred to.