PRODUCTION OF VINYL CHLORIDE POLYMER

Japanese Patent JPH1180213

A

PROBLEM TO BE SOLVED: To obtain a vinyl chloride polymer having a small particle size and a high bulk specific gravity even when the polymn. is completed within a short time by specifying, to a certain value or higher, the vol. percentage of a vinyl chloride monomer present in liq. vinyl chloride monomer drops each having a skin formed thereon at the early stage of conversion of the monomer to the polymer. SOLUTION: At least 70 vol.% of the total vinyl chloride monomer in the suspension is caused to present in liq. monomer drops each having a skin formed thereon before the conversion of the monomer to a polymer reaches 5.0%. Thus, a high quality is achieved even when the suspension polymn. of a vinyl chloride monomer in an aq. medium in the presence of an oil-soluble polymn. initiator and a dispersion stabilizer is completed within 4 hr. The dispersion stabilizer comprises partially saponified polyvinyl alcohol (A) having a degree of saponification of 75-90 mol.% and an average degree of polymn. of 2,000-4,000 and partially saponified polyvinyl alcohol (B) having a degree of saponification of 60-85 mol.% and an average degree of polymn. of 300-1,500 in a wt. ratio of A/B of (5/1)-(20/1) and is used in an amt. of 0.04-0.08 wt.% of the monomer.

SAWANO MASAO
TANAKA TOSHIHIKO

JP24522397A

March 26, 1999

September 10, 1997

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TOSOH CORP

C08F2/18; C08F2/20; C08F14/06; (IPC1-7): C08F2/18; C08F2/20; C08F14/06

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