| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a lubricant base oil excellent in the viscosity-temperature property and the thermal and oxidation stability, and capable of developing the function of an additive in a higher level in the case where the additive is blended. <P>SOLUTION: The lubricant base oil contains a saturated content of ≥95 mass%. The proportion of a cyclic saturated content in the saturated content is 0.1 to 10 mass%. The lubricant base oil satisfies expression (1): 1.435≤n20-0.002×kv100≤1.450, wherein n20 denotes a refractive index at 20°C of the lubricant base oil; and kv100 denotes a kinematic viscosity (mm<SP POS="POST">2</SP>/s) at 100°C of the lubricant base oil, and satisfies one condition of conditions: (I) the kinematic viscosity at 100°C is 2.0 to 3.0 mm<SP POS="POST">2</SP>/s, the viscosity index is 105 to 130, and the flow point is ≤-15°C; (II) the kinematic viscosity at 100°C is ≥3.0 mm<SP POS="POST">2</SP>/s and <4.5 mm<SP POS="POST">2</SP>/s, the viscosity index is 130 to 150, and the flow point is ≤-17.5°C; and (III) the kinematic viscosity at 100°C is 4.5 to 20 mm<SP POS="POST">2</SP>/s, the viscosity index is 140 to 160, and the flow point is ≤-15°C. <P>COPYRIGHT: (C)2013,JPO&INPIT |
