METHOD FOR PRODUCING VINYL CHLORIDE-BASED POLYMER

摘要

PROBLEM TO BE SOLVED: To provide a method for producing a vinyl chloride-based polymer in which a vinyl chloride-based polymer excellent in quality is obtained and polymerization time can remarkably be shortened without being accompanied by scaling. SOLUTION: This method for producing a vinyl chloride-based polymer features performing the suspension polymerization within five hours of polymerization time in the presence of a dispersion stabilizer consisting of (A) a partially saponified polyvinyl alcohol having a degree of polymerization of >=2,000 and a degree of saponification of >=75 mol.% and (B) a partially saponified polyvinyl alcohol having a degree of polymerization of 100-700 and a degree of saponification of 20-55 mol.% under a condition that the heat removal quantity in polymerization reaction through a reflux condenser is set to be 30-60% based on the total heat generation quantity of polymerization by using a grading blade having two or more grids in its longitudinal and transverse directions, having the ratio d (a blade diameter)/D (a tank diameter) of 0.40-0.50 and having the ratio Hub (the height of a bottom paddle blade)/H (the height of the grading blade) or <0.30.