VINYLPYRROLIDONE POLYMER SOLUTION, PROCESS FOR PRODUCING THE SAME, AND METHOD OF HANDLING VINYLPYRROLIDONE POLYMER

摘要

A high-concentration solution of a vinylpyrrolidone polymer having a low K value. It is usable in all applications including medical applications and applications where coloration is problematic. A monomer ingredient comprising N-vinylpyrrolidone as an essential ingredient, hydrogen peroxide, and ammonia are successively added to an aqueous solvent containing a copper catalyst and are polymerized at 55-90°C. The ammonia is used in an amount of 0.1-0.37 wt.% based on the N-vinylpyrrolidone. Thus, a solution of a vinylpyrrolidone polymer having a K value of 60 or smaller is obtained which has a concentration of the polymer of 40-60 wt.%. The solution has an N-vinylpyrrolidone content not higher than 10 ppm of the vinylpyrrolidone polymer, an alkanol concentration of 100 ppm or lower, and an ignition residue amount of 0.1 wt.% or smaller. A 50 wt.% solution of the vinylpyrrolidone polymer has a hue of 280 or less.