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

摘要

PROBLEM TO BE SOLVED: To provide a viscosity index improver which can sufficiently decrease a high shear viscosity at 100°C while maintaining a high shear viscosity at 150°C and can sufficiently secure low temperature fluidity, and to provide a lubrication oil additive and a lubricating oil composition containing the viscosity index improver.SOLUTION: There is provided a poly(meth)acrylate-based viscosity index improver having a polymer chain containing a structural unit represented by the formula (1) and a structural unit represented by the formula (2), where the Mw is 100000 or more and the ratio Mw/Mn is 1.6 or less.