| 摘要 |
Provided are an agent for improving a viscosity index, and a lubricant composition comprising the same agent which is useful for lubricant for power train(gear oil), oil for automatic transmitter, hydraulic fluid, engine oil, and so on. The agent for improving a viscosity index comprises a monomer(a) represented by the formula(1), CH2=C(R^1)-COO(A-O)n-(CH2)p-CH(R^2)-R^3, as essential monomer, and a copolymer(A) having Z average molecular weight(Mz) of 10,000-1,000,000. In the formula(1), R1 is hydrogen atom or methyl group, R2 and R3 may be identical or different and are a linear alkyl group of C1-C16, or a branched alkyl group of C3-C34, and number of successive methylene group of the branched alkyl group is less than 16, total carbon number of R2, R3, and p numbers of CH2 groups is 17-35, A is C2-C4 alkylene group, n is 0, or an integer of 1-20, p is 0, or an integer of 1-15. The lubricant composition comprises the agent for improving a viscosity index, and a base oil. The base oil has a kinematic viscosity of 2-10 mm^2/s at 100 deg.C and flash point of 160 deg.C or more. The lubricant composition comprises 0.1-30 wt% of the copolymer(A) based on weight of the composition. |
