HIGHLY SATURATED NITRILE COPOLYMER RUBBER, PROCESS FOR THE PRODUCTION THEREOF, HEAT-RESISTANT RUBBER COMPOSITIONS COMPRISING THE RUBBER AND COMPOSITES COMPRISING THE RUBBER AND FIBERS

摘要

A highly saturated nitrile copolymer rubber lowered in Mooney viscosity by 15 or more points by applying a high shearing stress thereto in the presence of an age resister, which has a Mooney viscosity of 5 to 135 and a ratio of weight-average molecular weight (Mw) to number-average molecular weight (Mn) of 3 to 5 and exhibits an increase in Mooney viscosity of as little as 10 or less points as measured after the rubber has been allowed to stand in the air at room temperature for 30 days after the above lowering of the Mooney viscosity. This rubber exhibits little viscosity change with the lapse of time and is excellent in processability and storage stability. The rubber can be blended with other heat-resistant rubbers to give heat-resistant rubber compositions, while it can be filled with fibers to give composites excellent in strength characteristics.