METHOD FOR PREPARING HOMOPOLYMER K90 AQUEOUS SOLUTION OF N-VINYL BUTYROLACTAM WITH LOW RESIDUAL MONOMER

摘要

Disclosed in the present invention is a method for preparing a homopolymer K90 aqueous solution of N-vinyl butyrolactam with low residual monomer, comprising: using 10-35% weight of an aqueous solution of N-vinyl butyrolactam monomer as a raw material in the presence of an inert gas, at a polymerization temperature of 55°C-90°C, carrying out a reaction under stirring for 2.5-4.5 h and during the reaction adding an initiator in batches, the initiator being a mixture of azodiisobutyronitrile and azobisisoheptonitrile and having a total amount of 0.01%-3% of the mass of N-vinyl butyrolactam monomer; after the K value of this system reaches 90-102, maintaining the temperature overnight at 95°C, adding a mixed acid in batches to adjust the pH to be at 2.0-7.0; during the removal of the residual monomer, the mixed acid being formed by mixing two acids selected from propane diacid, sulphuric acid and hydrochloric acid, so as to obtain 10-35% by weight of a colourless and transparent product residual monomer below 10 ppm and a stable K value of 90-102. The present invention is ingenious in design and simple in preparation. The prepared homopolymer K90 aqueous solution of N-vinyl butyrolactam has low residual monomer below 10 ppm, is colourless and stable in K value, and suitable for a large scale of popularization and application.