Lubricating oil composition and sliding mechanism

Abstract

A lubricating oil composition according to the present embodiment is a lubricating oil composition to be used in a sliding member coated with hydrogen-containing diamond-like carbon, and contains a base oil and a friction modifier. The friction modifier contains a fatty acid ester of pentaerythritol.

1 . A lubricating oil composition to be used in a sliding member coated with hydrogen-containing diamond-like carbon, the lubricating oil composition comprising:
 a base oil; and   a friction modifier, wherein   the friction modifier contains a fatty acid ester of pentaerythritol.   
     
     
         2 . The lubricating oil composition according to  claim 1 , wherein
 the fatty acid ester of pentaerythritol is contained in an amount of 0.2% by mass or more.   
     
     
         3 . The lubricating oil composition according to  claim 1 , wherein
 a total hydroxyl value of the fatty acid ester of pentaerythritol is 2.20 mgKOH/g or more.   
     
     
         4 . (canceled) 
     
     
         5 . (canceled) 
     
     
         6 . The lubricating oil composition according to  claim 1 , wherein
 the fatty acid ester of pentaerythritol is a plurality of esters selected from a pentaerythritol monoester, a pentaerythritol diester, a pentaerythritol triester, and a pentaerythritol tetraester.   
     
     
         7 . The lubricating oil composition according to  claim 2 , wherein
 a content of the fatty acid ester of pentaerythritol is 0.2% by mass or more and 10.0% by mass or less with respect to a total amount of the lubricating oil composition.   
     
     
         8 . The lubricating oil composition according to  claim 2 , wherein
 as the fatty acid ester of pentaerythritol, a pentaerythritol monoester or a pentaerythritol diester is contained in an amount of 2.0% by mass or more and 6.0% by mass or less with respect to a total amount of the lubricating oil composition.   
     
     
         9 . The lubricating oil composition according to  claim 1 , wherein
 the sliding member is a damper.   
     
     
         10 . The lubricating oil composition according to  claim 2 , wherein
 the sliding member is a damper.   
     
     
         11 . The lubricating oil composition according to  claim 3 , wherein
 the sliding member is a damper.   
     
     
         12 . The lubricating oil composition according to  claim 6 , wherein
 the sliding member is a damper.   
     
     
         13 . The lubricating oil composition according to  claim 7 , wherein
 the sliding member is a damper.   
     
     
         14 . The lubricating oil composition according to  claim 8 , wherein
 the sliding member is a damper.   
     
     
         15 . A sliding mechanism using the lubricating oil composition according to  claim 1 , wherein
 at least a sliding portion is coated with hydrogen-containing diamond-like carbon.   
     
     
         16 . The sliding mechanism according to  claim 15 , wherein
 a ratio of a normal dynamic friction coefficient to a very low speed friction coefficient, which is (normal dynamic friction coefficient)/(very low speed friction coefficient), is less than 1.20.