| 摘要 |
PROBLEM TO BE SOLVED: To obtain a rubber composition which can exhibit a low permanent set even at a low temperature and has excellent flexibility by making the composition include a rubber component such as an ethylene/propylene/diene rubber and/or an ethylene/propylene rubber with a softener in a specified ratio and include foams specified in its volume cell fraction. SOLUTION: This is a rubber composition prepared by compounding 100 pts.wt. rubber component such as an ethylene/propylene/diene rubber and/or an ethylene/propylene rubber with at least 200 pts.wt. softener, 0-300 pts.wt. reinforcement such as silica, 0-200 pts.wt. tackifier such as a liquid polybutene, and additives such as a flame retardant, a blowing agent, a vulcanizing agent, a vulcanization accelerator, and an antioxidant and containing 20-70 vol.% cells. The ethylene/propylene/diene rubber is one which has a Mooney viscosity of 90-130 and an iodine value of at most 20 and in which the diene is ethylidenenorbornene or dicyclopentadiene. The softener used is desirably a paraffinic process oil having a kinematic viscosity of at least 50 at 40 deg.C or an oil comprising a low-molecular-weight component of an ethylene/propylene copolymer.
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