Shin-etsu Chemical Co., Ltd.

Wako Pure Chemical Industries, Inc.

Hitoshi Ohba

Motoaki Tanaka

Genji Noguki

Takanori Toyama

Osamu Yamaguchi

Kenichi Itoh

The invention provides an improvement in the suspension polymerization of vinyl chloride in an aqueous medium in the presence of a monomer-soluble polymerization initiator, according to which the amount of polymer scale deposition on the reactor walls can be greatly decreased. The improvement comprises admixing the aqueous polymerization medium with (a) a water-soluble crosslinked copolymer of an unsaturated carboxylic acid monomer, e.g. acrylic acid, and a crosslinking monomer such as di(methyl)allyl ether of diethyleneglycol and (b) a non-ionic surface active agent in combination.

Method for the polymerization of vinyl chloride monomer in an aqueous

A stable aqueous suspension containing an organic azo compound as polymerization initiator in fine particles, containing substantially no organic solvent and containing no foam which damages dispersing stability of the aqueous suspension and retards polymerization rate can be formed by dissolving an organic azo compound in an organic solvent, emulsifying the resulting solution by adding water and a dispersing agent A and a dispersing agent B thereto with stirring, and removing the organic solvent from the emulsified liquid preferably under reduced pressure.

Process for producing aqueous suspension containing organic azo compound

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Saitama, Japan

Hitoshi Ohba