| 摘要 |
PURPOSE:The title composition, having improved performance at a high temperature, e.g. the flash point, and compatibility with a rubber material, satisfying the SAE standard in the United States, and comprising a specific hydrocarbon base oil containing a lower alkylbiphenyl and a viscosity index improver in a specific proportion. CONSTITUTION:A fluid composition comprising (A) 70-95wt% a hydrocarbon base oil consisting of (i) 40-99wt% polybutene having an average molecular weight of 100-500 and/or a 2-12C alpha-olefin (except butene) (co)polymer having an average molecular weight of 100-600, and (ii) 1-60wt% a lower alkylbiphenyl, preferably having a boiling point >=260 deg.C, a viscosity at 20 deg.C<=cP and a pour point <=0 deg.C, and (B) 5-30wt% a viscosity index improver consisting of a polymethacrylate having a viscosity-average molecular weight of 10,000-700,000, obtained by polymerizing an ester of a 1-18C saturated monohydric aliphatic alcohol with methacrylic acid. |
