Lubricating oil composition and device using same

Abstract

A lubricating oil composition contains a base oil containing a compound (A) and a compound (B) below and a compound (C). The lubricating oil composition exhibits a kinematic viscosity at 40 degrees C. in a range of 20 mm 2 /s to 40 mm 2 /s, a density at 15 degrees C. of 1.1 g/cm 3 or more, a flash point of 200 degrees C. or more, and a viscosity index of 100 or more. The compound (A) is an ester or an ether having two or more aromatic rings. The compound (B) is an ester or an ether having a kinematic viscosity at 40 degrees C. of 12 mm 2 /s or less, a density at 15 degrees C. of 0.9 g/cm 3 or more and a flash point of 100 degrees C. or more. The compound (C) is a poly(meth)acrylate having a mass average molecular weight of 50000 or less.

1 . A lubricating oil composition comprising:
 a base oil comprising a compound (A) and a compound (B); and   a compound (C), wherein   the compound (A) is an ester or an ether having two or more aromatic rings,   the compound (B) is an ester or an ether having a kinematic viscosity at 40 degrees C. of 12 mm 2 /s or less, a density at 15 degrees C. of 0.9 g/cm 3  or more and a flash point of 100 degrees C. or more,   the compound (C) is a poly(meth)acrylate having a mass average molecular weight of 50000 or less, and   the lubricating oil composition has a kinematic viscosity at 40 degrees C. in a range of 20 mm 2 /s to 40 mm 2 /s, a density at 15 degrees C. of 1.1 g/cm 3  or more, a flash point of 200 degrees C. or more, and a viscosity index of 100 or more.   
     
     
         2 . The lubricating oil composition according to  claim 1 , wherein the compound (A) is represented by any one of formulae (1), (2) and (3) below, 
       
         
           
           
               
               
           
         
         wherein n and m are each independently 0 or 1; p and q are each independently an integer of 0 to 3; and X and Y are each independently an alkyl group having 1 to 30 carbon atoms that optionally comprises a cycloalkyl group or an aromatic group, a cycloalkyl group or an aromatic group having 5 to 12 carbon atoms, an alkyloxycarbonyl group having 2 to 30 carbon atoms that optionally comprises a cycloalkyl group or an aromatic group, or an alkylcarbonyloxy group having 2 to 30 carbon atoms that optionally comprises a cycloalkyl group or an aromatic group, 
       
       
         
           
           
               
               
           
         
         wherein n and m are each independently 0 or 1; p and q are each independently an integer of 0 to 3; X and Y are each independently an alkyl group having 1 to 10 carbon atoms; and A is an alkylene group having 2 to 18 carbon atoms that optionally comprises oxygen in a main chain and/or optionally comprises a side chain, 
       
       
         
           
           
               
               
           
         
         wherein j, k, n and m are each independently 0 or 1; p and q are each independently an integer of 0 to 3; X and Y are each independently an alkyl group having 1 to 10 carbon atoms; and Z is an alkylene group having 1 to 18 carbon atoms that optionally comprises a side chain. 
       
     
     
         3 . The lubricating oil composition according to  claim 1 , wherein
 the compound (B) is one selected from the group consisting of adipic acid diester of ethyleneglycolmonobutylether, adipic acid diester of diethyleneglycolmonobutylether, 2-ethyl hexanoic acid diester of triethyleneglycol, dibutyl sebacate, dioctyl adipate, dioctyl azelate, dioctyl sebacate, dimethyl phthalate, diethyl phthalate, tetraethyl eneglycoldimethylether, and diethyl succinate.   
     
     
         4 . The lubricating oil composition according to  claim 1 , wherein
 a ratio of the compound (A) to the compound (B) in the base oil is from 2 to 10 by a mass ratio ((A)/(B)).   
     
     
         5 . The lubricating oil composition according to  claim 1 , wherein
 a total amount of the compound (A) and the compound (B) is 85 mass % or more of the base oil.   
     
     
         6 . The lubricating oil composition according to  claim 1 , wherein
 a ratio of the compound (A) is from 40 mass % to 95 mass % of a total amount of the composition.   
     
     
         7 . The lubricating oil composition according to  claim 1 , wherein
 a ratio of the compound (B) is from 5 mass % to 60 mass % of the total amount of the composition.   
     
     
         8 . The lubricating oil composition according to  claim 1 , wherein
 the lubricating oil composition is a lubricating oil composition or grease in a hydraulic device, a rotary device, a bearing or a gear.   
     
     
         9 . A device applied with the lubricating oil composition according to  claim 1 .