| 摘要 |
<p>The present invention relates to a process for the manufacture of insoluble and only slightly swellable polymers or copolymers of N-vinyl pyrrolidone, N-vinyl caprolactam and N-vinyl pipe idone, in which N-vinyl pyrrolidone or a mixture of N-vinyl pyrrolidone with from 5 to 100% by weight, based on N-vinyl pyrrolidone, of N-vinyl caprolactam or N-vinyl piperidone, is polymerized in dilute aqueous solution at pHs greater than 6 with the exclusion of oxygen and in the presence of a cyclic amide containing at least two ethylenically unsaturated groups, of which at least one is attached to an amide nitrogen atom, and in the presence of from 0.05 to 2% by weight, based on N-vinyl pyrrolidone, of at least one substance selected from the group consisting of ascorbic acid, ethyl acetoacetate and pyruvic acid, said polymerization being carried out at from 50.degree. tv 100.degree.C.</p> |
