Patent ID: 6965002
Filing Date: 2005-11-15
Classification: C08F

Abstract:
1. A process for producing a vinyl chloride-based polymer which comprises: polymerizing either a vinyl chloride monomer, or a mixture of a vinyl chloride monomer and another copolymerizable monomer therewith in an aqueous medium in a polymerization vessel equipped with a reflux condenser, removing heat generated in the polymerization, using said reflux condenser, and adding an aqueous solution of an ethylene oxide/propylene oxide copolymeric polyether with a weight average molecular weight of 1,500,000 to 2,000,000, and an ethylene oxide to propylene oxide molar ratio within a range from 78/22 to 82/18, as an antifoaming agent, in a quantity equivalent to 0.001 parts by weight to 0.008 parts by weight in terms of said copolymeric polyether per 100 parts by weight of said vinyl chloride monomer or the monomer mixture, to a polymerization mixture when a polymerization conversion is within 30% to 50%.