Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymerizing in two or more physically distinct zones
Patent
1979-06-29
1981-05-19
Wong, Jr., Harry
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymerizing in two or more physically distinct zones
428402, 526 78, 526 87, 526202, 526203, 526344, C08F 1406
Patent
active
042686512
ABSTRACT:
Vinyl chloride polymers are prepared by polymerization or copolymerization in mass, in two phases, comprising prepolymerizing vinyl chloride monomers in a first phase under highly turbulent agitation until a degree of conversion thereof between about 5 and 15% is attained, and thence, in a second distinct phase, polymerizing said prepolymerized reaction product through reaction completion under mild agitation, said process being characterized in that [1] there is added to the reaction medium, prior to same attaining a polymer content of about 15% by weight, an additive selected from the group comprising (a) a copolymer of vinyl acetate and an ethylenically unsaturated carboxylic acid monomer copolymerizable therewith, and (b) a condensate of ethylene oxide on a polypropylene glycol backbone, and in that [2] the reaction rate is controlled such that the period of time during which the content by weight of polymer or copolymer in the reaction medium is comprised between 15 and 25% is less than 45 minutes. The reaction product comprises at least 95% by weight of a fraction which will pass through a 250 micron mesh sieve.
REFERENCES:
patent: 3683051 (1972-08-01), Chatelain
Erard Francois
Soussan Salomon
Rhone-Poulenc Industries
Wong, Jr. Harry
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