Friction modifier and lubricant composition

Abstract

The present invention aims to provide a friction modifier having both a friction reducing effect and storage stability, and a lubricating oil composition containing the friction modifier and having a high friction reducing effect and high stability at high temperatures. The present invention relates to a friction modifier containing a copolymer (A) that contains, as essential constituent monomers, a monomer (a) represented by the following formula (1) and a monomer (b) represented by the following formula (2), the monomer (a) among copolymer (A)-constituting monomers having an average value of p per mole of the monomer (a) of 1 to 4, the copolymer (A) having a weight average molecular weight of 5,000 to 38,000, the copolymer (A) containing the monomer (a) in an amount of 10 to 60% by weight based on a total weight of the copolymer (A)-constituting monomers. The formula (1) is as follows: wherein A1 is a polymerizable group; —X1—, —X2—, and —X3— are each independently a group represented by —O— or —NH—; R1 is a C1-C4 alkylene group; R2 is a C2-C20 alkylene group; R3 is a hydrogen atom; and p is an integer of 1 to 100, where when p is 2 or more, a plurality of R2's are the same as or different from each other and a plurality of X3's are the same as or different from each other. The formula (2) is as follows: wherein R4 is a hydrogen atom or a methyl group; —X4— is a group represented by —O— or —NH—; and R5 is a linear or branched C5-C44 alkyl group.

Dependencies are inferred from the claim text.