| 摘要 |
Copolymers of vinyl alcohol and b -hydroxyalkyl acrylates wherein the alkyl groups contain 2 to 4 carbon atoms and optionally crotonic acid or an alkyl ester of crotonic acid in which the alkyl group contains 1 to 8 carbon atoms, may be prepared by copolymerizing vinyl acetate, a hydroxyalkyl acrylate and optionally crotonic acid or an alkyl crotonate and subjecting the resulting copolymer to alkaline alcoholysis. Polymerization may be effected in solution in organic solvents, e.g. acetone, methyl ethyl ketone, ethyl acetate and alcohols, in the presence of catalysts, e.g. benzoyl peroxide and azodiisobutyronitrile. The copolymers may be alcoholyzed in methanol or ethanol solution in the presence of alcoholic potassium hydroxide, sodium hydroxide, sodium methoxide or sodium ethoxide; and the products transferred to aqueous solution by precipitating and dissolving in water, or by adding water and distilling off residual alcohol and ester. Hydroxyethyl acrylate copolymers may be crosslinked by aging, heating or reacting with glyoxal, furfural, dimethylol ethylene urea, dimethylol urea, trimethylol phenol, trimethylol melamine, phosphoric acid, hydrochloric acid, oxalic acid, fumaric acid, para-toluene sulphonic acid, ferric chloride, chromic nitrate, chromic chloride, chromic sulphate, ammonium chloride, aluminium chloride, zinc nitrate, cupric chromate, ammonium dichromate and stearato chromic chloride. The copolymers or mixtures thereof with polyvinyl alcohol may be used in making flexible films for packaging, and for coating. Examples describe (I) the copolymerization of vinyl acetate, hydroxyethyl acrylate and crotonic acid in methanol in the presence of benzoyl peroxide and the alcoholysis of the product in the presence of methanol and potassium hydroxide, (II) copolymers of vinyl alcohol and hydroxyethyl, hydroxypropyl or hydroxybutyl acrylates with and without crotonic acid, and (III) the copolymerization of vinyl acetate, hydroxypropyl acrylate and crotonic acid in methyl acetate in the presence of azodiisobutyronitrile and the alcoholysis of the product in the presence of methanol and potassium hydroxide. |
