| 摘要 |
PROBLEM TO BE SOLVED: To obtain a rubber composition which can give a rubber vibration isolator improved in vibrationproofing properties, durability and heat resistance by mixing a specified random copolymer rubber with a filler and a vulcanizer. SOLUTION: Fifty (50) to 80mol% ethylene is copolymerized with 50-20mol% 3-20Cα-olefin and a branched polyene compound of the formula (wherein (n) is 1-5; R<1> is a 1-5C alkyl; and R<2> and R<3> are each H or a 1-5C alkyl) at 50-150 deg.C for 5min to 5hr under a pressure of 80kg/cm<3> or above in the presence of a catalyst comprising a transition metal compound and an organoaluminum(oxy) compound to obtain a random copolymer (A) having an iodine value of 5-30 and an intrinsic viscosity of 1.0-6.0dl/g (in decalin at 135 deg.C). One hundred (100) pts.wt. component A is mixed with 20-100 pts.wt. filler (B), 0.5-10 pts.wt. vulcanizer (C) and 1-20 pts.wt. vulcanization accelerator (D), and the resultant mixture is kneaded at 40-80 deg.C for 5-30min to obtain a rubber composition for a rubber vibration isolator, which has a loss tangent (tanδ) of 0.03-0.15 when determined by a dynamic viscoelasticity test after being vulcanized.
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