GB1314096A - Elastomers - Google Patents

Abstract

1314096 Acrylic block polymers ROHM & HAASCO 22 May 1970 [26 May 1969] 24843/70 Heading C3P A process for the production of vulcanizable acrylic elastomers comprises, in a first stage, polymerizing, in suspension or emulsion in a liquid medium, an initial monomer charge containing (i) at least 45% by weight, based on the weight of the charge, of an alkyl acrylate monomer, the homopolymer of which has a glass transition temperature below - 35‹ C., or a mixture of alkyl acrylate monomers, the copolymer of which has a glass transition temperature below - 35‹ C., (ii) from 0-5% by weight of a polyethylenically unsaturated monomer, (iii) from 0-10% by weight of a curing site-containing monomer, and (iv) from 0-50% by weight of at least one monomer selected from alkoxyalkyl acrylates, alkylthioalkyl acrylates, cyanoalkoxyalkyl acrylates and nitrile-substituted alkyl acrylates; and, in a subsequent and final stage, polymerizing in contact with the suspended polymer product of the preceding stage a final monomer charge containing (i) at least 60% by weight, based on the weight of the final monomer charge, of ethyl and/or methyl acrylate, (ii) 0-40% by weight of one or more other alkyl acrylates or substituted alkyl acrylates, (iii) 0- 40% by weight of a nitrile-containing monomer, and (iv) 0-10% by weight of curing sitecontaining monomer. The preferred alkyl acrylates are butyl, hexyl and/or 2-ethylhexyl acrylate; the polyethylenically unsaturated monomer may be butylene diacrylate, butylene dimethacrylate or divinyl benzene; other monomers may be 2-methoxyethyl acrylate, 2- ethoxyethyl acrylate, 2-ethyl-thioethyl acrylate, 4-cyanobutyl acrylate and/or 2-cyanoethyl acrylate, and the curing site-containing monomer may be 2-chloroethyl-vinyl ether, vinyl chloroacetate, beta-(chloroacetoxy)-ethyl-methacrylate and/or 4-chloro-2-buten-1-yl acrylate. Between the first and final polymerization stages may be interposed at least one intermediate polymerization stage in which an intermediate monomer charge is polymerized in contact with the suspended polymer product of the first stage and before polymerization of the final stage, the intermediate monomer charge containing (i) ethyl acrylate and (ii) an alkyl acrylate monomer, the homopolymer of which has a glass transition temperature below - 35‹ C., and, optionally, (iii) a polyfunctional crosslinking monomer, a curing site-containing monomer or an oil-resistance improving monomer.