Patent ID: 9428601
Filing Date: 2016-08-30
CPC Classification: C08F

Claim Text:
1. A method of preparing a vinyl chloride homopolymer comprising: polymerizing vinyl chloride monomer in the presence of a solvent, a polymerization initiator, a protective colloid auxiliary, and a pH regulator at a polymerization temperature of 30° C. to 75° C., wherein 120 to 150 weight part of the solvent, 0.02 to 0.2 weight part of the polymerization initiator, 0.03 to 5 weight part of the protective colloid auxiliary and 0.01 to 1.5 weight part of the pH regulator are added to 100 weight part of the vinyl chloride monomer; adding a first amount of additional vinyl chloride monomer when a polymerization conversion rate ranges from 30% to 40% at the polymerization temperature; polymerizing the first additional vinyl chloride monomer at the polymerization temperature; adding a second amount of additional vinyl chloride monomer and an antioxidant to the reactor when the polymerization conversion rate reaches 60 to 70%; and polymerizing the second amount of additional vinyl chloride monomer at a temperature that is 5° C. to 20° C. higher than the polymerization temperature to obtain an average polymerization degree of 700 to 1300; wherein the antioxidant is added in an amount of 0.001 to 0.03 weight part for 100 weight part of the vinyl chloride monomer, and wherein the polymerization initiator is one or more compounds selected from the group consisting of dicumyl peroxide, dilauryl peroxide, di-2-ethylhexylperoxydicarbonate and t-butylperoxyneodecanoate.