abstract |
A nitrite group-containing highly saturated copolymer rubber having α,β-ethylenically unsaturated nitrile monomer units (a) and conjugated diene monomer units (b) and having at least part of said conjugated diene monomer units (b) hydrogenated, wherein a content of said α,β-ethylenically unsaturated nitrile monomer units (a) is 37 to 45 wt%, a total of said α,β-ethylenically unsaturated nitrile monomer units (a) and said conjugated diene monomer units (b) is 93 wt% or more, an iodine value is 9 or less, and a half value width of a peak of a loss tangent (tanδ) in the viscoelastic properties when made into a cross-linked product is 5 to 20°C in range. |