Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Patent
1989-12-27
1992-02-11
Henderson, Christopher
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
526202, C08F 220
Patent
active
050876783
ABSTRACT:
Foaming above the aqueous polymerization mixture can be efficiently reduced in suspension polymerization of vinyl chloride monomer in an aqueous medium contained in a polymerization reactor equipped with a reflux condenser for removal of the heat of polymerization by admixing the polymerization mixture with additives comprising (a) from 0.002 to 0.007 part by weight of a partially saponified polyvinyl alcohol having a degree of saponification in the range from 20 to 50% by moles and an average degree of polymerization in the range from 200 to 400 and (b) from 0.001 to 0.01 part by weight of a silicone-based defoaming agent, each amount being per 100 parts by weight of the vinyl chloride monomer or the monomer mixture mainly composed of vinyl chloride, at a moment, preferably, before the reflux condenser is brought into operation. By this improvement, the resultant polyvinyl chloride resin product may have a greatly improved bulk density and particle size distribution without causing polymer scale deposition on the reactor walls.
REFERENCES:
patent: 3277064 (1966-10-01), Lovelock
patent: 4455413 (1984-06-01), Tomishima
patent: 4464519 (1984-08-01), Mango
Patent Abstracts of Japan, vol. 9, No. 331 (C-321) (2054) Dec. 25, 1985, & JP-A-60 158206 (Toyo Soda Kogyo K.K.) Aug. 19 1985.
Patent Abstracts of Japan, vol.10, No. 303 (C-378) (2359) Oct. 16, 1986, & JP-A-61 115908 (Kanegafuchi Chem Ind. Co. Ltd.) Jun. 3, 1986.
Hoshida Shigehiro
Kuwabara Kouzou
Noguki Genji
Henderson Christopher
Shin-Etsu Chemical Co. , Ltd.
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