| 摘要 |
PURPOSE:To obtain a hydraulic oil composition for shock absorber excellent in retention or a friction-reducing effect by incorporating at least one specific phosphorus compound and at least one specific nitrogen compound as essential ingredients into a lubricating oil base. CONSTITUTION:This composition comprises, as essential components, a lubricating oil base, at least one phosphorus compound selected from among a phosphoric ester (a) represented by formula I, a phosphorous ester (b) represented by formula II, and a salt of an 8-22C aliphatic monoamine with at least either of the esters (a) and (b), and at least one nitrogen compound selected from an aliphatic polyamine represented by formula III and a salt of a 6-22C fatty acid with the polyamine. In formula I and II, R<1> and R<4> each is a 4-22C alkyl or alkenyl, etc. and R<2>, R<3>, R<5>, and R<6> each is hydrogen, a 1-22C alkyl or alkenyl, etc. In formula III, R<7> is a 6-22C alkyl, etc.; R<8> is a 2-4C alkylene; and (a) is a number of 1-4. |
