SUSPENSION POLYMERIZATION PROCESS FOR PREPARING VINYL CHLORIDE POLYMER AND COPOLYMER

摘要

PROBLEM TO BE SOLVED: To produce a vinyl chloride polymer or copolymer by suspension- polymerizing a vinyl chloride monomer composition in the presence of variable quantities of oxygen in a sealed reactor by using a reaction mixture including water, a monomer composition, an oil-soluble polymerization initiator, a specified polyvinyl alcohol, etc. SOLUTION: In a process for producing a vinyl chloride polymer or copolymer by suspension-polymerizing a vinyl chloride monomer composition in the presence of variable quantities of oxygen in a sealed reactor, the reaction mixture comprises water, a monomer composition, at least one polymerization initiator soluble in an organic solvent, at least one oxidized polyvinyl alcohol and optionally a dispersant. The oxidized polyvinyl alcohol is desirably one obtained by heat-treating a polyvinyl alcohol obtained by hydrolyzing polyvinyl acetate in an oxidizing medium and is used in an amount of 0.001-0.5%, desirably 0.01-0.2wt.% based on the weight of the monomer composition.