| 摘要 |
863,229. Vinyl alcohol-crotonic acid copolymers. AIR REDUCTION CO., Inc. Sept. 5, 1958 [Sept. 5, 1957], No. 23526/60. Divided out of 863,228. Class 2(6). Vinyl alcohol-crotonic acid copolymers are made by reacting a vinyl acetate-crotonic acid copolymer with an excess of a C 1 to C 4 alkanol in the presence of a base, soluble in the alkanol, the amount of such base being at least sufficient to substantially completely neutralize the free carboxyl groups and to catalyze the alcoholysis of the acetyl groups of the copolymer. The reaction may proceed at ambient temperature and yields the salt of the vinyl alcohol-crotonic acid copolymer which can be converted to the corresponding acid form by treatment with acid. The base may be sodium or potassium hydroxide or sodium or potassium methylate and the alkanol may be methanol or ethanol. The copolymers may be made into sheets or films as disclosed in Specification 863,228. The initial vinyl acetate-crotonic acid copolymer may be prepared by polymerization in aqueous suspension in the presence of benzoyl peroxide and partially hydrolysed polyvinyl acetate. |
