| abstract |
PROBLEM TO BE SOLVED: To provide an unsaturated nitrile-conjugated diene rubber capable of forming a vulcanized rubber excellent in workability and excellent in mechanical strength, oil resistance and the like, and a rubber composition containing the rubber. And a method for producing the same. SOLUTION: After polymerization is started using a predetermined amount of an olefinically unsaturated nitrile monomer and a conjugated diene monomer, these monomers are continuously or stepwisely mixed at a specific quantitative ratio. To continue the polymerization, as a repeating unit, (A) It has an olefinically unsaturated nitrile monomer unit such as acrylonitrile and (B) a conjugated diene monomer unit such as butadiene, and the total amount of (A) and (B) is 100% by mass. When (A) is 55 to 80% by mass, particularly 6% More than 0% by mass, the glass transition point is -15 to 30C, particularly -10 to 20C, and the extrapolation end temperature of the glass transition is 7 An unsaturated nitrile-conjugated diene rubber having a temperature of 0 ° C or lower, particularly 50 ° C or lower is obtained. |