Lubricant oil composition for rotary compressor

Abstract

A lubricating oil composition for a rotary compressor capable of imparting high extreme pressure property while maintaining high oxidation stability is provided by mixing, in (a) a base oil, (b) an antioxidant and (c) a dithiophosphate ester compound represented by the formula (I) in an amount of 0.05% by mass or more and less than 2.0% by mass based on the total composition.

1 . A lubricating oil composition for a rotary compressor, comprising (a) a base oil, (b) an antioxidant, and (c) a dithiophosphate ester compound represented by the following formula (I) in an amount of 0.05% by mass or more and less than 2.0% by mass based on the total amount of the composition: 
       
         
           
           
               
               
           
         
         wherein R 1  represents a linear or branched alkylene group having from 1 to 8 carbon atoms; and R 2  and R 3  each represent a hydrocarbon group having from 3 to 20 carbon atoms. 
       
     
     
         2 . The lubricant oil composition for a rotary compressor according to  claim 1 , wherein the lubricating oil composition comprises (c) the dithiophosphate ester compound represented by the following formula (I) in an amount of more than 0.1% by mass and less than 2% by mass. 
     
     
         3 . The lubricating oil composition for a rotary compressor according to  claim 1 , wherein R 1  represents a linear or branched alkylene group having from 1 to 8 carbon atoms; and R 2  and R 3  each represent a linear or branched alkylene group having from 3 to 20 carbon atoms. 
     
     
         4 . The lubricating oil composition for a rotary compressor according to  claim 1 , wherein (b) the antioxidant is at least one kind selected from a phosphorus compound, a phenol compound, a phenylamine compound, and a napthylamine compound. 
     
     
         5 . The lubricating oil composition for a rotary compressor according to  claim 1 , wherein the lubricating oil composition comprises the antioxidant in an amount of 0.01% by mass or more and 10% by mass or less. 
     
     
         6 . The lubricant oil composition for a rotary compressor according to  claim 1 , wherein the base oil is a mineral oil. 
     
     
         7 . The lubricating oil composition for a rotary compressor according to  claim 1 , wherein the rotary compressor is a gear-driven rotary compressor. 
     
     
         8 . The lubricating oil composition for a rotary compressor according to  claim 1 , wherein the rotary compressor is a screw compressor, a movable vane compressor, a scroll compressor, or a tooth compressor.