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PROCESSES FOR PREPARING CROSSLINKED COPOLYMERS

IP.com Disclosure Number: IPCOM000025938D
Original Publication Date: 1989-Feb-28
Included in the Prior Art Database: 2004-Apr-04
Document File: 2 page(s) / 102K

Publishing Venue

Xerox Disclosure Journal

Abstract

Disclosed is a process for preparing crosslinked styrene butadiene copolymers by free radical suspension polymerization. More specifically, styrene/butadiene/divinylbenzene ternary polymers are prepared by a suspension free radical polymerization, preferably in an aqueous solution, in the resence of monomers such as styrene, butadiene, and divinylbenzene or simi P ar crosslinking components, and two initiators, one a low temperature initiator and the second a high temperature initiator. Included in the reaction formulation is an ionic, water soluble surfactant and a monomer insoluble stabilizer. Preferably, the ratio of the styrene monomer to the butadiene monomer is from about 80:20 to about 95:5 by weight, and the weight roportion of water to the combination of styrene and butadiene monomers is from about 8:l to about 2:l. Preferably, the low temperature initiator is insoluble in water and soluble in the styrene monomer and in the butadiene monomer, and has a 1 hour half-life between about 50°C and about llO"C, and the high temperature initiator is insoluble in water and soluble in the styrene monomer and in the butadiene monomer, and has a 1 hour half-life between about 115°C and about 130°C.

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Proposed Classification

US. C1.430/105 Int. C1. G03g 9/00

Disclosed is a process for preparing crosslinked styrene butadiene copolymers by free radical suspension polymerization. More specifically, styrene/butadiene/divinylbenzene ternary polymers are prepared by a suspension free radical polymerization, preferably in an aqueous solution, in the resence of monomers such as styrene, butadiene, and divinylbenzene or simi P ar crosslinking components, and two initiators, one a low temperature initiator and the second a high temperature initiator. Included in the reaction formulation is an ionic, water soluble surfactant and a monomer insoluble stabilizer. Preferably, the ratio of the styrene monomer to the butadiene monomer is from about 80:20 to about 95:5 by weight, and the weight roportion of water to the combination of styrene and butadiene monomers is from about 8:l to about 2:l. Preferably, the low temperature initiator is insoluble in water and soluble in the styrene monomer and in the butadiene monomer, and has a 1 hour half-life between about 50°C and about llO"C, and the high temperature initiator is insoluble in water and soluble in the styrene monomer and in the butadiene monomer, and has a 1 hour half-life between about 115°C and about 130°C.

The polymerization is usually accomplished in two stages; during the first stage, the bulk of the polymerization occurs at, for example, a temperature of from about 50°C to about 115"C, at which temperature the reaction mixture is maintained for an effective period of time, generally from about 2 to about 5 hours. In the second stage, a high temperature initiator is included to reduce the level of resid...