HDRAULIC FLUID COMPOSITION HAVING HIGH VISCOSITY INDEX WITH IMPROVED THERMAL-OXIDATIVE STABILITY

摘要

PURPOSE: A hydraulic fluid composition with an improved thermal-oxidative stability is provided to enhance major properties including oxidation stability, thermal stability, stickiness and flash point. CONSTITUTION: A liquid hydraulic fluid composition includes a liquid viscosity index improver containing 80~90wt% of lubricating base oil included in an API Group III, 10~20wt% of polymer and 0~0.1wt% of antioxidant selectively. The polymer is selected from the group consisting of PMA(poly methacrylate) or OCP(olefin copolymers) has the polymer molecular weight of 20,000~500,000 and 100deg C dynamic viscosity of 100 ~ 2,000 centistokes. 1.0~15.0wt% of liquid viscosity index improver is included in the liquid hydraulic fluid composition.