COPOLYMER AND LUBRICATING OIL COMPOSITION

摘要

The problem of the invention is to provide a lubricating oil composition having excellent heat resistance (suppressed discoloration upon heating) and stickiness while maintaining the excellent viscosity characteristics of lubricating oil compositions that use ricinoleic acid polymers. The invention provides: a copolymer (B) in which structural units (a) derived from ricinoleic acid, structural units (b) derived from an aliphatic dicarboxylic acid, and structural units (c) derived from a C2-10 diol are contained in a specific ratio, the copolymer (B) having a specific intrinsic viscosity; and a lubricating oil composition containing a base oil and the copolymer (B), the mass ratio (mass of (A)/mass of (B)) of the base oil (A) and the copolymer (B) in the lubricating oil composition being 60/40-99.5/0.5.