Lubricant composition

Abstract

A lubricant composition which, in a sliding member, is interposed between a DLC-coated surface and another metal member, in particular, a steel material, the lubricant composition having good wear resistance as well as having a better friction reducing effect than conventional molybdenum friction modifier-containing lubricant compositions. The lubricant composition is characterized by containing a lubricating base oil, (A) molybdenum dialkyl dithiophosphate, and (B) zinc dialkyl dithiophosphate, wherein the amount of phosphorus with respect to the total mass of the lubricant composition is 300-1500 mass ppm.

1 . A lubricant composition comprising a lubricant base oil, (A) a molybdenum dialkyldithiophosphate, and (B) a zinc dialkyldithiophosphate, and having a phosphorus content of 300 to 1500 ppm by weight based on a total weight of the lubricant composition. 
     
     
         2 . The lubricant composition according to  claim 1 , wherein the lubricant composition further comprises (A′) at least one selected from the group consisting of an amine friction modifier and an amide friction modifier at a content of less than 0.1% by weight based on the total weight of the lubricant composition. 
     
     
         3 . The lubricant composition according to  claim 1 , comprising component (A) at a content of 400 to 1300 ppm by weight in terms of ppm by weight of molybdenum based on the total weight of the lubricant composition, and component (B) at a content of 200 to 1000 ppm by weight in terms of ppm by weight of phosphorus based on the total weight of the lubricant composition. 
     
     
         4 . The lubricant composition according to  claim 1 , for use in lubrication of diamond-like carbon (DLC) films. 
     
     
         5 . The lubricant composition according to  claim 1 , for use in lubrication of opposed sliding surfaces of sliding members, wherein the sliding members are a pair of sliding members having opposed sliding surfaces which can move relative to each other, and wherein at least one of the sliding surfaces comprises a surface coated with a diamond-like carbon (DLC) film. 
     
     
         6 . The lubricant composition according to  claim 4 , wherein the DLC film comprises boron. 
     
     
         7 . The lubricant composition according to  claim 1 , wherein the lubricant composition has a high temperature high shear viscosity (HTHS viscosity) at 150° C. of 1.4 to 2.9 mPa·s. 
     
     
         8 . The lubricant composition according to  claim 1 , wherein the lubricant composition has a kinematic viscosity at 100° C. of 9.3 mm 2 /s or less. 
     
     
         9 . The lubricant composition according to  claim 1 , for use in internal combustion engines. 
     
     
         10 . The lubricant composition according to  claim 1 , wherein the lubricant composition does not comprise (A′) at least one selected from the group consisting of an amine friction modifier and an amide friction modifier. 
     
     
         11 . The lubricant composition according to  claim 2 , comprising component (A) at a content of 400 to 1300 ppm by weight in terms of ppm by weight of molybdenum based on the total weight of the lubricant composition, and component (B) at a content of 200 to 1000 ppm by weight in terms of ppm by weight of phosphorus based on the total weight of the lubricant composition. 
     
     
         12 . The lubricant composition according to  claim 2 , wherein the lubricant composition has a high temperature high shear viscosity (HTHS viscosity) at 150° C. of 1.4 to 2.9 mPa·s. 
     
     
         13 . The lubricant composition according to  claim 3 , wherein the lubricant composition has a high temperature high shear viscosity (HTHS viscosity) at 150° C. of 1.4 to 2.9 mPa·s. 
     
     
         14 . The lubricant composition according to  claim 4 , wherein the lubricant composition has a high temperature high shear viscosity (HTHS viscosity) at 150° C. of 1.4 to 2.9 mPa·s. 
     
     
         15 . The lubricant composition according to  claim 5 , wherein the lubricant composition has a high temperature high shear viscosity (HTHS viscosity) at 150° C. of 1.4 to 2.9 mPa·s. 
     
     
         16 . The lubricant composition according to  claim 6 , wherein the lubricant composition has a high temperature high shear viscosity (HTHS viscosity) at 150° C. of 1.4 to 2.9 mPa·s. 
     
     
         17 . The lubricant composition according to  claim 2 , wherein the lubricant composition has a kinematic viscosity at 100° C. of 9.3 mm 2 /s or less. 
     
     
         18 . The lubricant composition according to  claim 3 , wherein the lubricant composition has a kinematic viscosity at 100° C. of 9.3 mm 2 /s or less. 
     
     
         19 . The lubricant composition according to  claim 4 , wherein the lubricant composition has a kinematic viscosity at 100° C. of 9.3 mm 2 /s or less. 
     
     
         20 . The lubricant composition according to  claim 5 , wherein the lubricant composition has a kinematic viscosity at 100° C. of 9.3 mm 2 /s or less.