Patent GB-825611-A (GB)
Title: Difficultly inflammable styrene polymers and the production of the same
IPC: C08K5/06
Filed: 1957-03-01
Abstract: Polymers and copolymers of styrene and its homologues, e.g alpha-methylstyrene, o-, m- or p-methyl styrene, ar-dimethylstyrenes or arethylstyrenes, e.g. with copolymerizable monomers such as acrylonitrile, N-vinylcarbazole, methyl methacrylate or acrylate or vinyl esters are rendered difficulty inflammable by the incorporation of an ester of 2,3-dibromopropanol-1 in an amount such that the composition contains 0.2 to 6% of bromine, based on the styrene polymer.  The polymers may be cross-linked by a monomer such as divinyl benzene, diallyl maleate, allyl acrylate, triallyl phosphate or butanediol-1,4-divinyl ether.  The dibromopropanol ester may be an ester of phosphoric, cyanuric, carbonic, acetic, oxalic or succinic acid and is preferably added to the styrene before polymerization or it may be incorporated into the polymer afterwards, e.g. by mechanical mixing or by steeping with an alcoholic solution of the ester.  The polymerization may be carried out in bulk, or by the solution, suspension, or emulsion methods in the presence of initiators such as benzoyl, lauroyl or cyclohexanone peroxides or azo-di-isobutyronitrile.  A blowing agent may also be incorporated into the polymer, by addition before or after polymerization, to yield expandable polymers which are expanded or foamed by heating at temperatures above the softening-point of the styrene polymer.  The blowing agent may be a volatile liquid or gas, e.g. petroleum ether, pentane, hexane, cyclohexane, cyclopentane, butane, propane, carbon dioxide or difluorodichloromethane.  There may be present in the mixture when the styrene-type monomer is being polymerized by aqueous suspension, suspension stabilizers such as barium sulphate, sodium pyrophosphate or polymers or copolymers of N-vinylpyrrolidone and the product may be in the form of beads. The difficulty inflammable polymers may also contain polyisobutylene and bromine binders such as phenoxypropene oxide, amines or zinc cadmium or lead stearate.  In an example a terpolymer of styrene, acrylonitrile and divinylbenzene is treated with the bromo-ester.ALSO:Polymers of styrene and its homologues e.g alpha-methylstyrene, o-, m- or p-methylstyrene, ar-dimethylstyrenes or ar-ethylstyrenes, e.g. copolymers with acrylonitrile, N-vinylcarbazole, methyl methacrylate or acrylate or vinyl esters are rendered difficultly inflammable by the incorporation of an ester of 2, 3-dibromopropanol-1 in an amount such that the compsoition contains 0,2 to 6,0% of bromine, based on the styrene polymer.  The polymers may be cross-linked to a small extent by a monomer such as divinyl benzene, diathyl maleate, alkyl acrylate, triallyl phosphate or butanediol-1, 4-divinyl ether.  The dibromopropanol ester may be incorporated before or after polymerization and may be an ester of phosphoric, cyaneric, carbonic, acetic, oxalic or succinic acid.  A blowing agent may be added to the polymer or to the monomer to yield expandable polymers which are expanded or foamed by heating at temperatures above the softening-point of the styrene polymer. The blowing agent may be a volatile liquid or gas e.g. petroleum ether, pentane, hexane, cyclohexane, cyclopentane butane, propane, carbon dioxide or difluorodichloromethane.  The difficultly inflammable polymers may also contain polyisobutylene and bromine binders such as phenoxypropene oxide, amines or zinc, cadmium or lead stearate.