| 摘要 |
PROBLEM TO BE SOLVED: To provide a viscosity index improver which realizes a lubricant composition with high metal friction reducibility, excellent shear stability and low HTHS viscosity, and hardly increases low-temperature viscosity.SOLUTION: A viscosity index improver comprises a copolymer (A) comprising a monomer (a) represented by the general formula (1) as an essential constituent monomer. [Ris H or a methyl group; Xis O or NH; Rare C2-4 linear or branched alkylene groups; p is an integer from 0 to 20; when p is 2 or more, Rmay be identical or different, and (RO)moiety may have random bonds or block bonds; Y is a C1-5 linear or branched alkylene group; and Rare each independently a C1-8 alkyl group.]SELECTED DRAWING: None |
