OIL FILM THICKNESS INCREASING AGENT AND LUBRICANT COMPOSITION

摘要

PROBLEM TO BE SOLVED: To provide an oil film thickness increasing agent excellent in shear stability and viscosity index improving performance. SOLUTION: The oil film thickness increasing agent comprises a copolymer (A) which comprises an alkyl (meth)acrylate (a) with a 1-36C alkyl group as an essential constituent monomer and satisfies the following requirements (i)-(iv): (i) the adsorption INDEX determined by a test of adsorption to iron oxide is≥1.5; (ii) the coefficient Km representing the intermolecular interaction calculated by the Martin's formula is≥1; (iii) the average side chain length calculated based on the molar percentages of monomer units is≤11; and (iv) the weight average molecular weight is 3,000-1,000,000. COPYRIGHT: (C)2009,JPO&INPIT