GB949305A - Polymer and method of making same - Google Patents

Abstract

The invention claimed is any normally solid copolymer of an olefinically unsaturated monomer with maleic anhydride or halogenated maleic anhydride in molar proportions from 1:2 to 2:1 characterized by a solution viscosity in 10% solution in acetone of up to 7 centistokes. The method specified for preparing such copolymers comprises simultaneously adding the monomers and a free-radical generating polymerization catalyst to a reaction mass comprising an organic solvent, in which the monomers are soluble but the copolymer is not appreciably soluble, which contains copolymer and less than 3 wt. per cent of unreacted monomers (if any), and which is maintained at a temperature at which (a) a mixture of all the materials being supplied thereto, would explode and (b) fusion of the copolymer to form a toffee-like mass is avoided, each monomer being supplied in an amount of at least 5% by weight of the total material supplied and the rate of supply of the monomers being controlled so as not substantially to exceed the rate of removal thereof by the copolymerization reaction. Preferred solvents comprise a C6 monocyclic hydrocarbon nucleus with at least one C2 or higher alkyl or alkaryl substituent with a free halogen on the alpha carbon. Such solvents have a chain terminating effect. In the particular description the comonomer is styrene, other comonomers mentioned are vinyl toluene, ethyl acrylate, methyl methacrylate, acrylonitrile, methyl vinyl ether, ethylene, propylene, butene-1 and -2, diallyphthalate; and vinyl chloride. Catalysts specified are benzoyl, 1-hydroxy cyclohexyl, acetone, dilauryl, di-t-butyl, diocetyl and acetyl benzoyl peroxides; peroxides obtained by oxidising the preferred solvents in situ; t-butyl and cumene hydroperoxides; and azodiisobutyronitrile. Cobalt salt and amine accelerators may be used in conjunction therewith.