Patent GB-761904-A (GB)
Title: Improvements in the production of polystyrene
Inventor: ARDLEY STANLEY MAURICE
IPC: C08F236/04
Filed: 1954-04-13
Abstract: Tough, flexible polystyrene-type compositions are prepared by polymerizing one or more monovinyl aromatic compounds, e.g. styrene, methyl and ethyl styrenes and chlorostyrenes, in which is dispersed a synthetic rubber containing more than 50 per cent of gelled material. The rubber may be prepared by polymerizing a butadiene-type compound, e.g. butadiene-1,3, isoprene, 2,3-dimethyl butadiene-1,3 or chloroprene, or copolymerizing it with minor proportions of other butadienes or monoethylenically unsaturated compounds, e.g. styrene, methyl styrenes, meta-ethyl styrene, para-ethyl styrene, paraisopropyl styrene, ortho-chlorostyrene, parachlorostyrene, ortho - para - dimethyl styrene, acrylonitrile, methyl isopropenyl ketone, alphamethyl styrene, methyl - alpha - methyl styrene, ar - dimethyl - alpha - methyl styrene, ethyl - alpha - methyl styrene, isopropylalpha - methyl styrene, ar - chloro - alphamethyl styrene, ar - dichloro - alpha - methyl styrene, or ar - chloro - ar - methyl - alphamethyl styrene.  The gelling of the rubber may be brought about by cross-linking, by continuing the polymerization beyond the normal stage, by using a cross-linking comonomer, e.g. divinyl or trivinyl benzenes, naphthalenes, anthracenes, phenanthrenes, carbazoles or pyridines, di-isopropenyl benzenes or naphthalenes, allyl or vinyl esters of phthalic, succinic, oxalic, maleic, fumaric, itaconic, citraconic, acrylic or methacrylic acids, or the diacrylates or dimethacrylates of ethylene, propylene, butylene, diethylene or dipropylene glycols, or by heating the rubber solid, solution or dispersion with vulcanizing agents, e.g. sulphuryl chloride, organic or inorganic peroxides, diphenyl 4,41-di(sulphonylazide), quinones, quinone oximes, zinc alkyls, sulphur, piperidine pentamethylene dithiocarbamate, mercaptobenzothiazole, zinc diethyl dithiocarbamate, cyclo-hexyl benzthiazylsulphenamide, zinc isopropyl xanthate, tetramethyl thiuram disulphide, diphenylguanidine, zinc oxide, cumene hydroperoxide or oxygen.  Latices may be spray dried or coagulated in the presence of a polystyrene dispersion. Polymerization is effected in bulk in an inert solvent, e.g. ethyl benzene, in emulsion or by a "bead" process, using heat, light or a catalyst, e.g. benzoyl peroxide, cumene hydroperoxide, tertiary butyl perbenzoate, a -hydroxy a 1-hydroperoxy diisopropyl benzene or azo or nitroso compounds, preferably in the absence of atmospheric oxygen, at 40 DEG  to 250 DEG  C. in one or more stages.  Plasticizers, lubricants, mould release and antistatic agents may be added.  In examples: (1) tetramethyl thiuram disulphide and zinc diethyl dithiocarbamate are dispersed in a butadiene-styrene copolymer latex which is heated, blended with a polystyrene latex and coagulated by adding to 64 per cent overproof industrial methylated spirits containing formic acid, and the coagulate dispersed in styrene which is polymerized by heating; (18) to (23) butadiene-styrenedivinyl benzene terpolymers and light liquid paraffin are dispersed in styrene which is polymerized by heating.