VISCOSITY INDEX IMPROVER, METHOD FOR PRODUCING SAME, AND OIL COMPOSITION

摘要

The present invention provides a viscosity index improver that is excellent in an effect of improving a viscosity index and a high-temperature high-shear viscosity of oils, etc. The viscosity index improver of the present invention includes a hydrogenated product of a copolymer containing a constitutional unit (a) derived from an aromatic vinyl compound and a constitutional unit (b) derived from a conjugated diene, a content of a constitutional unit (b1) derived from farnesene in a whole amount of the constitutional unit (b) derived from the conjugated diene being from 1 to 100% by mass, and a content of a constitutional unit (b2) derived from a conjugated diene other than farnesene in a whole amount of the constitutional unit (b) derived from the conjugated diene being from 0 to 99% by mass, and 50 mol% or more of carbon-carbon double bonds in the constitutional unit (b) derived from the conjugated diene being hydrogenated.