US Patent 11091577 Nitrile group-containing highly saturated copolymer rubber

The present invention provides a nitrile group-containing highly saturated copolymer rubber comprising an α,β-ethylenically unsaturated nitrile monomer unit in a content of 15 wt % or more and less than 28 wt %, an α,β-ethylenically unsaturated monocarboxylic acid ester monomer unit (b) in a content of 10 to 50 wt %, and a conjugated diene monomer unit (c) in a content of 22 to 75 wt %, and having an iodine value of 120 or less, wherein the conjugated diene monomer unit (c) is at least partially hydrogenated, and a proportion of an isoprene unit in the conjugated diene monomer unit (c) is 33 wt % or more.