ACRYLIC COPOLYMERS

摘要

1437176 Copolymers containing anhydride units IMPERIAL CHEMICAL INDUSTRIES Ltd 18 July 1973 [14 Aug 1972 13 June 1973] 37804/72 and 28170/73 Heading C3P A thermoplastic copolymer comprising from 50 to 99% by weight of the copolymer of units derived from a main ethylenically unsaturated monomer which monomer is either an alkyl methacrylate having from 1 to 4 carbon atoms in the alkyl group or styrene optionally containing up to 15% by weight of the main monomer used of other of other copolymerizable ethylenically unsaturated monomers excluding ethylenically unsaturated carboxylic acids, and correspondingly from 1 to 50% by weight of the copolymer of a mixture of ethylenically unsaturated carboxylic acid and carboxylic acid anhydride units derived from an α-substituted acrylic acid, at least 5% by weight of the mixture being in the form of anhydride units and wherein the copolymer has a melt flow index of at least 0À1 may be prepared by treating the polymerization product of a main ethylenically unsaturated monomer and an α-substituted acrylic acid at a temperature above its full Vicat softening point until at least 5% by weight of the copolymerized α- substituted acrylic acid has been converted to carboxylic acid anhydride units. In the examples copolymers of methacrylic acid, methyl methacrylate, styrene and n-butyl acrylate are extruded into lace using an extruder fitted with a vacuum degassing vent system.