Hydraulic fluid composition
View Patent ↗The present invention provides a hydraulic oil composition comprising: a lubricating base oil having a kinematic viscosity at 40° C. of 15 to 50 mm 2 /s; and 1 to 40% by mass, based on a total amount of the hydraulic oil composition, of a polymethacrylate having a number-average molecular weight of 48000 or lower, the hydraulic oil composition having a viscosity index of 150 or higher, and a ratio (A/B) at 60 to 80° C. of (A) a kinematic viscosity (unit: mm 2 /s) to (B) a shear viscosity (unit: mPa·s, shear condition: 10 6 /s) of 1.3 or lower.
1. A hydraulic oil composition comprising:
a lubricating base oil having a kinematic viscosity at 40° C. of 15 to 50 mm 2 /s; and
15 to 40% by mass, based on a total amount of the hydraulic oil composition, of a polymethacrylate having a number-average molecular weight of 48000 or lower,
the hydraulic oil composition having a viscosity index of 150 or higher, and a ratio (A/B) at 60 to 80° C. of (A) a kinematic viscosity (unit: mm 2 /s) to (B) a shear viscosity (unit: mPa-s, shear condition: 10 6 /s) of 1.3 or lower.
2. The hydraulic oil composition according to claim 1 , wherein a sulfur content of the lubricating base oil is 10 ppm by mass or lower.