GB833571A - Interpolymers and interpolymerisation processes employing the same - Google Patents

Abstract

Interpolymers are made consisting of 93.5 to 98.5 mol. per cent of acrylic and/or methacrylic acid and 6.5 to 1.5 mol. per cent of 2-ethylhexyl acrylate and/or methacrylate, at least one part by weight of interpolymer being soluble in 199 parts of water at 25 DEG C. The interpolymers are made by polymerizing the monomers in mass or, preferably, in solution in a solvent such as pentane, hexane, octane, petroleum ethers, benzene, toluene, xylene, ethylbenzene, chlorobenzene, 1,2 - dichloroethane, chloroform and carbon tetrachloride, the latter solvents serving to reduce the molecular weight of the polymer, and in the presence of catalyst such as benzoyl, lauroyl, ditertiary butyl, oleyl and toluyl peroxides and azo-bis-isobutyronitrile; also present may be a small quantity of sulphur dioxide. During the course of the reaction additional solvent may be charged in order to maintain the reaction mass in a stirrable condition. The copolymers are used as dispersing agents in the suspension polymerization of (1) vinyl aromatic compounds such as styrene, alpha-methyl and -ethyl styrenes, alpha-methyl vinyltoluene, vinyl toluene, o- and p-ethyl styrenes, 2,4-dimethylstyrene, o- and p-chlorostyrenes, o-bromostyrene, 2,4 - dichlorostyrene, 2 - chloro - 4 - methyl styrene, 2,6-dichloro-4-methyl styrene, vinyl naphthalene and anthracene and divinyl benzene and mixtures thereof with monomers such compounds with butadiene, isoprene, acrylic acid, methyl, ethyl, butyl and 2-ethylhexyl acrylates and methacrylates, acrylonitrile, methacrylonitrile acrylamide and methacrylamide and also natural rubber or a rubbery butadiene polymer, and (2) vinyl halides such as vinyl fluoride, chloride and bromide and mixtures thereof with monomers such as vinyl acetate, propionate, butyrate, stearate and benzoate, vinylidene chloride, trichlorethylene, methyl, ethyl, butyl and allyl acrylates and methacrylates, acrylamide, methacrylamide, acrylanilide, acrylonitrile, methacrylonitrile and C1-C8 alkyl and allyl and methallyl maleates, fumarates, citraconates and itaconates. The suspension polymerization reactions are catalysed by peroxides of the type described above and the pH of aqueous medium is preferably below 7.0, e.g. from 3.0 to 4.0. The addition of the copolymeric dispersing agent to the aqueous suspension of monomer may be delayed until the latter has undergone polymerization to the extent of 20 to 30%; alternatively the monomer may be prepolymerized, to the extent of 20 to 30% before being charged to an aqueous medium containing the dispersing agent. In the case of the vinyl aromatic compound suspension polymerization a low-boiling aliphatic hydrocarbon may be incorporated during polymerization in order to prepare foamable beads of polymer. In the case of vinyl halide suspension polymerization there may be added to the reaction mixture particle size reducing agents such as C10-C18 unsaturated aliphatic monocarboxylic acids and their halogen substituted derivatives, C10-C20 hydroxyl-substituted aliphatic monocarboxylic acids, partial esters of C10-C20 aliphatic monocarboxylic acid with C2-C20 polyhydric alcohols, e.g. glycerol mono-octadecanoate, and plasticizers such as C2-C10 dialkyl phthalates, C2-C9 fatty acid esters of C2-C10 glycols and phosphoric acid of phenol, cresols and xylenols. In Examples (33 and 34) involving the suspension polymerization of styrene the reaction are carried out in the presence of a small quantity of dodecyl mercaptan.