PROCESS FOR THE SYNTHESIS OF A HIGH VINYL ISOPRENE-BUTADIENE COPOLYMER

摘要

PROCESS FOR THE SYNTHESIS OF A HIGH VINYL ISOPRENE-BUTADIENE COPOLYMER Isoprene-butadiene copolymers having high vinyl contents can be synthesized in organic solvents to high yields after short polymerization times by utilizing the process of this invention. The isoprene-butadiene copolymers made utilizing the process of this invention have a glass transition temperature which is within the range of about 0.degree.C to about -60.degree.C and can be employed in tire treads which provide improved traction and improved cut growth resistance. This invention specifically discloses a process for the synthesis of isoprene-butadiene copolymers having a high vinyl content which comprises copolymerizing isoprene monomer and butadiene monomer in an organic solvent at a temperature. which is within the range of about -10.degree.C to about 100.degree.C in the presence of a catalyst system which is comprised of (a) an organoiron compound, (b) an organoaluminum compound, (c) a chelating aromatic amine, and (d) a protonic compound; wherein the molar ratio of the chelating amine to the organoiron compound is within the range of about 0.1:1 to about 1:1, wherein the molar ratio of the organoaluminum compound to the organoiron compound is within the range of about 5:1 to about 200:1, and wherein the molar ratio of the protonic compound to the organoaluminum compound is within the range of about 0.001:1 to about 0.2:1.