| 摘要 |
PROBLEM TO BE SOLVED: To obtain the subject improver for an engine oil, etc., capable of imparting an excellent low temperature viscosity when used in a high viscosity index oil by compounding (meth)acrylate polymers having specific alkyl carbon numbers at specific ratios. SOLUTION: This improver is composed of a mixture of (A) a polymer consisting of (i) an 8-12C alkyl group-containing alkyl (meth)acrylate, (B) a polymer consisting of (ii) 0-90 mol% of a 1-13C alkyl group-containing alkyl (meth)acrylate and (iii) 10-100 mol% of a 14-24C alkyl group-containing alkyl (meth)acrylate, and (C) a polymer consisting of 3-87 mol% of the component (ii) and 13-97 mol% of the component (iii). In the modifier, the glass transition temperature of the polymer A is <=-40 deg.C, the difference between the percentage of the component (ii) in the component B and that of the component (ii) in the component C, and the difference between the percentage of the component (iii) in the component B and that of the component (iii) in the component C are both >=3 mol%, and the components A, B and C are contained in amounts of 80-99 wt.%, 0.1-19.9 wt.% and 0.1-19.9 wt.%, respectively. |
