Lubricating oil composition for traction drive transmission

Abstract

An object of the present invention is to provide a lubricating oil composition capable of improving oxidation stability by allowing a base number to remain, preserving seizure resistance, preventing generation of precipitation to be caused due to addition of a base, and inhibiting a lowering of traction coefficient. The lubricating oil composition for traction drive transmission includes (A) a base oil, (B) a phosphate ester-based compound, (C) an antioxidant, and (D) an amine represented by the following general formula (I) and/or an amine oxide of the amine. In the general formula (I), each of R 1 and R 2 independently represents a linear, branched, or cyclic alkyl group having 1 to 26 carbon atoms, a linear, branched, or cyclic alkenyl group having 1 to 26 carbon atoms, (R 4 —O) m —H, or (R 5 —O) n1 —(R 6 —O) n2 —H, and R 1 and R 2 may be the same as or different from each other; each of R 4 to R 6 independently represents an alkylene group having 2 to 3 carbon atoms; each of m, n1, and n2 independently represents a number of 2 to 25; and R 3 represents a substituted or unsubstituted, linear, branched, or cyclic alkyl group having 1 to 26 carbon atoms, or a substituted or unsubstituted, linear, branched, or cyclic alkenyl group having 1 to 26 carbon atoms.

1 . A lubricating oil composition for traction drive transmission preparing by blending (A) a base oil, (B) a phosphate ester-based compound, (C) an antioxidant, and (D) an amine represented by the following general formula (I) and/or an amine oxide of the amine: 
       
         
           
           
               
               
           
         
         wherein each of R 1  and R 2  independently represents a linear, branched, or cyclic alkyl group having 1 to 26 carbon atoms, a linear, branched, or cyclic alkenyl group having 1 to 26 carbon atoms, (R 4 —O) m —H, or (R 5 —O) n1 —(R 6 —O) n2 —H, and R 1  and R 2  may be the same as or different from each other; each of R 4  to R 6  independently represents an alkylene group having 2 to 3 carbon atoms; each of m, n1, and n2 independently represents a number of 2 to 25; and 
         R 3  represents a substituted or unsubstituted, linear, branched, or cyclic alkyl group having 1 to 26 carbon atoms, or a substituted or unsubstituted, linear, branched, or cyclic alkenyl group having 1 to 26 carbon atoms. 
       
     
     
         2 . The lubricating oil composition for traction drive transmission according to  claim 1 , wherein the base oil as the (A) component is a naphthene-based synthetic oil. 
     
     
         3 . The lubricating oil composition for traction drive transmission according to  claim 1 , wherein in the amine represented by the general formula (I), the sum total of carbon number of R 1  to R 3  is 10 to 40. 
     
     
         4 . The lubricating oil composition for traction drive transmission according to  claim 1 , wherein in the amine represented by the general formula (I), R 1  and/or R 2  is a methyl group, and R 3  is an unsubstituted alkyl group having 8 to 22 carbon atoms. 
     
     
         5 . The lubricating oil composition for traction drive transmission according to  claim 1 , wherein the phosphate ester-based compound as the (B) component and the amine represented by the general formula (I) and/or the amine oxide of the amine as the (D) component are blended in a mass ratio of 35/1 to 2/1. 
     
     
         6 . The lubricating oil composition for traction drive transmission according to  claim 1 , wherein 80 to 99% by mass of the base oil as the (A) component, 0.05 to 10% by mass of the phosphate ester-based ester compound as the (B) component, 0.1 to 1.6% by mass of the antioxidant as the (C) component, and 0.05 to 4% by mass of the amine represented by the general formula (I) and/or the amine oxide of the amine as the (D) component are blended.