| 摘要 |
Porous hydrolysed or partially hydrolysed vinyl ester polymers are made by forming a solution of the ester in a liquid which is a non-solvent for the solid alcoholysis product, e.g. benzene, acetone, methanol, methyl acetate and mixtures, continuously mixing a stream of the polymer solution with a stream of an alcoholic solution, e.g. methanol, of an alkaline alcoholysis catalyst and conveying the mixture, e.g. on an endless belt, conveyers, troughs, or rotating casting wheels, without further mixing or agitation through a reaction zone of uniform temperature until gelation of the reactants and syneresis of the resultant gel occurs. Optionally the catalyst is neutralized with an acid in a liquid which is a non-solvent for the solid product, e.g. methanol, methyl acetate, ligroin and mixtures. The ester polymers specified are polyvinyl acetate, propionate, and formate, and copolymers of vinyl acetate with ethylene, methyl methacrylate and dimethyl fumarate. Catalysts mentioned are sodium and potassium hydroxides and alcoholates. |
