| abstract |
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. |