Polymeric compositions and methods for their production

Claim 1

A process for making a polymeric composition of matter of the terpolymer type, said process having as its only essential steps the steps of: forming an elastomeric substrate by emulsion copolymerization of from 50-60 percent by weight of a rubber-forming, linear, diene monomer and from 40-50 percent by weight of an aromatic vinyl monomer at a temperature in the range of 65°-85° and in the presence of a free radical catalyst, a C 10 -C 18 mercaptan chain transfer agent, and 0.3-1.5% by weight of an aromatic, divinyl, cross-linking agent until a conversion of at least 95 percent is attained; effecting a graft polymerization of at least one of the group consisting of acrylic and methacrylic polymers on said substrate by dosing said substrate simultaneously at a substantially constant rate with a monomeric constituent consisting of at least one C 1 -C 3 ester of methacrylic or C 2 -C 4 ester of acrylic acid at an ester: substrate ratio of 1:3 to 1:4 and with a chain transfer agent, a catalyst, and a 0.2-0.6% by weight of cross-linking agent, all as aforesaid, the dosing being carried out in emulsion at a temperature in the range of 80° to 95° for a period of 3.5 to 5.5 hours; continuing the reactions for a period of 1 to 2 hours after the dosing is completed; and thereafter recovering the polymer from the emulsion, that being the final step in the making of the composition.