POLY(METH)ACRYLATE-BASED VISCOSITY INDEX IMPROVER, LUBRICANT ADDITIVE AND LUBRICANT COMPOSITION CONTAINING VISCOSITY INDEX IMPROVER

摘要

The present invention provides a poly(meth)acrylate-based viscosity index improver having a core, and three or more arms comprising a polymer chain containing a structural unit represented by formula (1) and a structural unit represented by formula (2), one end of said polymer chain being bonded to the core. The weight-average molecular weight (Mw) of the poly(meth)acrylate-based viscosity index improver is at least 100,000, and the weight-average molecular weight/the number average molecular weight (Mn) is not more than 1.6. [R1 represents hydrogen or a methyl group; R2 represents the group represented by formula (3); and R3 represents an alkyl group with 1 to 18 carbons. m and n are integers that satisfy m >= 5, n >= 4, and m + n <= 31.]