Patent ID: 7579305

Claim:
A friction modifier composition for a lubricating oil which comprises an oil-soluble copolymer (A) and a diluent, said oil-soluble copolymer (A) containing at least one unit of a monomer (a) represented by the general formula (1) and at least one unit of a monomer (b) represented by the general formula (2), and having a weight average molecular weight of 3,000 or more: CH 2 ═C(R 1 )-Q-(Z-A 1 ) m -X (1) CH 2 ═C(R 3 )—CO—(O-A 2 ) n -OR 4 (2) in the formula, X is a polar group represented by the formula —PH 2 , —NH 2 or —(O) a —P(═O) b (OR 2 ) 2 ; either of a or b is 1, and the other is 0 or 1; two R 2 s are the same or different and each represents H, an alkyl group having 1 to 24 carbon atoms, a group represented by the formula -(A 1 -Z) m -Q-C(R 1 )+CH 2 or a cation of M 1/f ; M is a f valent cation; f is 1 or 2; R 1 represents H or a methyl group; Z represents —O—; A 1 represents an alkylene group having 2 to 18 carbon atoms; m represents an integer of 1 or 2 to 50; Q represents —CO—; R 3 represents H or a methyl group; n represents an integer of 0 or 1 to 30; A 2 represents an alkylene group having 2 to 18 carbon atoms; R 4 represents an aliphatic hydrocarbon group having 1 to 32 carbon atoms, an alicyclic hydrocarbon group having 5 to 7 carbon atoms, or an aralkyl group having 7 to 32 carbon atoms; when there are a plurality of A 1 , R 1 , m and A 2 , they may be the same or different, and said diluent being at least one selected from the group consisting of high flash point solvent having flash point of 130° C. or more, aliphatic hydrocarbons, alcohol solvents, amide solvents, and sulfoxide solvents.