GB1026912A - Novel copolymers of methyl methacrylate - Google Patents

Abstract

Novel copolymers are prepared by polymerizing a monomer mixture comprising 1 to 99% by weight of methyl methacrylate, 99 to 1% by weight of one or more N-aryl maleimides and 0 to 15% by weight of a copolymerizable ethylenically unsaturated compound. Suitable maleimides include N-phenyl maleimide optioally substituted by one or more halogen atoms or nitro, nitrile, aryl, aryloxy, aralkyl, aralkoxy, aryloxyalkyl, C1-4 alkyl or C1-4 alkoxy groups, and N-a -naphthyl maleimide and derivatives thereof. As optional copolymerizable compound there may be used vinyl esters, e.g. vinyl acetate, esters of acrylic or methacrylic acid, e.g. methyl acrylate, ethyl acrylate, n-butyl methacrylate and 2-ethylhexyl methacrylate, vinyl chloride, vinylidene chloride, acrylonitrile, methacrylonitrile, styrene, a -methyl-styrene, halogenated styrenes, vinyl and isopropenyl ethers, e.g. vinyl isobutyl ether, dienes, e.g. 1,3-butadiene, glycol dimethacrylate and di-vinyl-benzene. The polymerization may be effected in bulk, solution, aqueous emulsion or aqueous suspension, using a catalyst such as azo-bis isobutyronitrile, azo-dicyclohexane-carbonitrile, a peroxy compound, e.g. benzoyl peroxide or lauroyl peroxide, or potassium persulphate and, if desired, a chain transfer agent, e.g. lauryl mercaptan. The monomers may be partially polymerized to form a syrup which is then polymerized in a cell to form a sheet. Continuous polymerization can be effected by the process described in Specification 875,853. The copolymers may be combined with rubbery polymeric materials, e.g. copolymers of butadiene with styrene, methyl methacrylate or acrylonitrile; polyethyl acrylate; rubbery copolymers of C1-4 alkyl acrylates; rubbery copolymers of ethylene with e.g. vinyl acetate or methyl methacrylate. The rubbery polymers can be cross-linked, e.g. by masticating or incorporating therein a cross-linking monomer. The rubbery polymer may simply be mixed with the copolymer of the invention, or the monomeric components of one of these polymers may be polymerized in the presence of the other preformed polymer. Other ancillary ingredients may be added during or after the preparation of the novel copolymers; such substances include fillers, e.g. glass fibres, pigments, e.g. aluminium sulphate, heat and light stabilizers, plasticizers, lubricants, flame retardants and mould release agents.