Patent ID: 6780945
Filing Date: 2004-08-24
Classification: C08F

Abstract:
A process for producing a vinyl chloride polymer, comprising conducting polymerization of vinyl chloride or of a monomer mixture comprised of mainly vinyl chloride in an aqueous medium in a polymerization vessel fitted with a reflux condenser, said process comprising:initiating the polymerization of the monomers; starting the operation of said reflux condenser to remove heat generated by the polymerization, conducting recovery of unreacted monomers from said polymerization vessel after the completion of said polymerization, and starting the continuous addition of (A) an anti-foam agent, and (B) a partially saponified polyvinyl alcohol with an average degree of polymerization of 100 to 500 and a saponification degree of 75 to 85 mole % to the polymerization mixture in said polymerization vessel during the operation of said reflux condenser, and continuing the addition of (A) and (B) stated above until the completion of the recovery of unreacted monomers.