Unsaturated nitrile-conjugated diene rubber composition and production process thereof

摘要

An objective of the present invention is to provide an unsaturated nitrile-conjugated diene-typed rubber capable of giving a vulcanized rubber which exhibits is well-balanced in terms of the mechanical strength, the oil resistance and the like, as well as a process for the production of the same, and a rubber composition which is containing such rubber and exhibits an excellent processability as well as a process for the production of the same. The unsaturated nitrile-conjugated diene-typed rubber in the invention is produced by polymerizing using certain amounts of an olefinically unsaturated nitrile monomer such as acrylonitrile and a conjugated diene monomer such as butadiene at first, and continuing by supplying a remainder of the monomers at a certain ratio continuously or stepwise to proceed the polymerization. The unsaturated nitrile-conjugated diene-typed rubber is constituted 55 to 80wt% of an olefinically unsaturated nitrile monomer unit as a repeating unit and 20 to 45wt% of a conjugated diene monomer unit as a repeating unit based on 100wt% of total of the monomer units. Glass transition temperature is -15 to 30 DEG C and the extrapolated temperature of the termination of the glass transition is preferably 70 DEG C or less.