| 摘要 |
PROBLEM TO BE SOLVED: To obtain a rubber composition capable of forming a rubber member having damping performances which does not change depending upon temperature change and is approximately constant in a temperature range of -30 to 20 deg.C at which instruments are supposed to work. SOLUTION: This rubber composition comprises a block copolymer of styrene and isoprene, a polymer composed of an isoprene part containing a vinyl isoprene unit and a polymer which is a partially brominated substance of a copolymer of isobutylene and p-methylstyrene. The composition after vulcanization has difference between the minimum and the maximum of dissipation factor tanδat - 30 to 20 deg.C of <=0.5 and the minimum of tanδof >=0.5.
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