Patent ID: 6472464
Filing Date: 2002-10-29
Classification: B60C,C08C,C08F,C08K,C08L

Abstract:
A styrene-butadiene copolymer wherein:a total styrene content is in the range of 33 to 42% by weight of the styrene-butadiene copolymer; a content of styrene sequences having 4 to 20 styrene units is in the range of 40 to 65% by weight of the total styrene content, as measured by nuclear magnetic resonance spectroscopy and gel permeation chromatography in combination; a content of styrene sequences having more than 20 styrene units is in the range of 5% by weight or less of the total styrene content, as measured by gel permeation chromatography; a content of vinyl unit is in the range of 30% by mol or less of the butadiene part of the styrene-butadiene copolymer; a sum of the total styrene value and Â½ of the content of vinyl units is in the range of 46 to 52%; and wherein the styrene-butadiene copolymer is obtained by copolymerizing styrene and butadiene in a hydrocarbon solvent in the presence of (1) an organolithium initiator selected from the group consisting of methyllithium, ethyllithium, propyllithium, n-butyllithium, sec-butyllithium, t-butyllithium, hexyllithium, octyllithium, tetramethylenedilithium, pentamethylenedilithium, hexamethylenedilithium, phenyllithium, tolyllithium, lithium naphthylide and benzyllithium and dilithium formed by the reaction of diisopropenylbenzene and butyllithium, (2) at least one type of potassium compound selected from the group consisting of potassium alcoholates, potassium sulfonates, and potassium carboxylates, and (3) at least one type of compound selected from the group consisting of ether compounds and amine compounds, and adding a compound selected from the group consisting of tin compounds, isocyanate compounds, imidazolidinone compounds, and aminobenzophenone compounds as a coupling agent or a modifier to the copolymerization product after copolymerization has been completed.