| 摘要 |
PURPOSE:To obtain a rubber composition having excellent crack-growth resistance under repeated application of large strain and high cut resistance and abrasion resistance, by compounding an isoprene rubber, a resin composed mainly of methylhexadiene/propylene and a specific carbon black. CONSTITUTION:The objective composition can be produced by compounding (A) >=30pts.wt. of a rubber containing >=30wt% isoprene, (B) 1-15pts.wt. of a resin of formula (R is H or CH3; m is 5-100) and composed mainly of methyl-1,4-hexadiene and propylene and/or ethylene and (C) a carbon black having an iodine adsorption of >=40mg/g and a DBP oil absorption of >=90m$/100g. The amount of then carbon black is 2.5 times the weight of the component B. The component B is a resin of formula wherein >=30%, preferably >=60% of the group R is methyl and m is 5-100 and the number-average molecular weight of the resin is 10,000-100,000. The crystal melting point of the polypropylene segment is >=130 deg.C.
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