VISCOSITY INDEX IMPROVER COMPOSITION AND LUBRICANT COMPOSITION

摘要

PROBLEM TO BE SOLVED: To provide a viscosity index improver composition more excellent in oxidation stability than a conventional polymethacrylate viscosity index improver composition. SOLUTION: The viscosity index improver composition comprises a polymer (A) containing an alkyl (meth)acrylate (a) with a 1 to 30C alkyl as an essential constituent monomer and a diluent (B), wherein (B) is a diluent containing not more than 0.5 mass% sulfur based on the mass of (B). The lubricant composition comprises the viscosity index improver composition and a base oil. COPYRIGHT: (C)2006,JPO&NCIPI