| 摘要 |
A rubber composition having not only oil resistance, heat resistance, and wearing resistance but high tensile strength and high tensile stress; and a modifier for preparing the same. By way of example, a modifier which comprises a carboxylated, highly saturated copolymer rubber containing nitrile groups and has an acid equivalent of 1.63x10<-2> ephr, a value of the ratio of the height of the peak assignable to the carboxylic anhydride group to the sum of the height of the peak assignable to the carboxylic anhydride group and the height of the peak assignable to the carboxyl group in infrared absorption spectromety of 0.96, a Mooney viscosity of 65, an iodine value of 28, and a methly-ethyl-ketone-insolubles content of 0.2 % is prepared by masticating a highly saturated polymer rubber containing nitrile groups with a pressure kneader (capacity: 75 liters; MS type), introducing 1.8 parts by weight of maleic anhydride and 0.5 parts by weight of 2,6-di-tert-butyl-4-methylphenol (BHT) into the pressure kneader after the rubber temperature has reached 130 DEG C, continuously kneading the resultant mixture (prekneading) so as to regulate the rubber temperature to 250 DEG C by utilizing the heat of shearing generated by kneading, and further kneading the mixture at that temperature for 15 minutes to cause the rubber to undergo an ene-addition reaction. Incorporating this modifier into a polyether rubber serves to give the objective rubber composition having the aforementioned properties.
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