Method for production of vinyl chloride-based polymer by suspension polymerization

A method of preparing vinyl chloride polymer comprising:

• suspension-polymerizing vinyl chloride monomer in the presence of a protective colloid auxiliary, a polymerization initiator at a polymerization temperature,
• introducing additional vinyl chloride monomer
• (a) when the polymerization conversion rate reaches from 30 to 40%;
• and
• (b) when the polymerization conversion rate reaches from 60 to 70%,
• suspension-polymerizing the additional vinyl chloride monomer at the polymerization temperature, and
• adding one or more antioxidants selected from a group consisting of a phenol based antioxidant, an amine based antioxidant, a sulfur based antioxidant and a phosphate based antioxidant when the pressure of a reactor reaches 6.0 kg/cm2, to complete the suspension-polymerizing,
• wherein the additional vinyl chloride monomer is not introduced when the polymerization conversion rate is between 40 to 60%,
• wherein the amount of the additional vinyl chloride monomer added when the polymerization conversion rate reaches between 30 and 40% is from 15 to 25 weight part for 100 weight part of the total amount of the monomer;
• wherein the amount of the additional vinyl chloride monomer added when the polymerization conversion rates reaches between 60 to 70% is from 15 to 25 weight part for 100 weight part of the total amount of the monomer;
• wherein the protective colloid auxiliary is present in an amount of between 0.05 and 2.5 weight part for 100 weight part of the total amount of the monomer, and
• wherein the polymerization initiator is present in an amount of between 0.02 and 0.2 weight part for 100 weight part of the total amount of the monomer.