| 摘要 |
Vinyl pyrrolidone/vinyl acetate copolymers having a very low residual vinyl pyrrolidone monomer level, i.e. <100 ppm, preferably only 50 ppm, are made within an advantageously short production cycle, by post-treating an aqueous solution of the copolymer at an elevated temperature of about 120-150° C., preferably about 130° C., under pressure, in the presence of a high temperature initiator, for a period of about 1-4 hours, preferably 2 hours.
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