Lubricant composition

Abstract

The present disclosure is directed to a lubricant composition that achieves extended anti-shudder durability without causing a decrease in the metal-to-metal friction coefficient, even when the viscosity of the composition is reduced. A lubricant composition comprises (A) a lubricant base oil, (C) (C-1) a succinimide compound or boronated succinimide compound having a weight-average molecular weight of 4,000 to 7,000, (C-2) a succinimide compound or boronated succinimide compound having a weight-average molecular weight of more than 7,000 to 10,000, and (D) (D-1) an amide-based friction modifier.

1 . A lubricating oil composition comprising
 (A) a lubricant base oil,   (C) (C-1) a succinimide compound or boronated succinimide compound having a weight-average molecular weight of 4,000 to 7,000, and (C-2) a succinimide compound or boronated succinimide compound having a weight-average molecular weight of more than 7,000 and not more than 10,000, and   (D) (D-1) an amide friction modifier.   
     
     
         2 . The lubricating oil composition according to  claim 1 , further comprising (D) (D-2) a friction modifier composed of a reaction product of boric acid or boron oxide with an epoxide. 
     
     
         3 . The lubricating oil composition according to  claim 1 , comprising, as a part or all of component (A), 5 to 30 percent by weight, based on a total weight of the lubricating oil composition, of a poly-α-olefin or α-olefin copolymer having a kinematic viscosity at 100° C. of 6 to 80 mm 2 /s, and further comprising (B) a polymethacrylate having a weight-average molecular weight of 15,000 to 40,000. 
     
     
         4 . The lubricating oil composition according to  claim 1 , wherein a part or all of component (C-1) and component (C-2) is a boronated succinimide compound. 
     
     
         5 . The lubricating oil composition according to  claim 4 , wherein each of component (C-1) and/or component (C-2) contains 0.1 to 3 percent by weight of boron, based on a weight of component (C-1) or component (C-2). 
     
     
         6 . The lubricating oil composition according to  claim 1 , wherein the weight ratio of component (C-1) to component (C-2), i.e., (C-2)/(C-1), is 1 to 10. 
     
     
         7 . The lubricating oil composition according to  claim 1 , wherein the succinimide compound is represented by following formula (1) or (2): 
       
         
           
           
               
               
           
         
         wherein R1 is each independently an alkyl or alkenyl group having 40 to 400 carbon atoms, m is an integer of 1 to 20, and n is an integer of 0 to 20. 
       
     
     
         8 . The lubricating oil composition according to  claim 1 , having a kinematic viscosity of 100° C. of 3 to 10 mm 2 /s. 
     
     
         9 . The lubricating oil composition according to  claim 1 , having a viscosity index of not less than 150. 
     
     
         10 . The lubricating oil composition according to  claim 1 , wherein compound (D-1) is at least one selected from amide compounds derived from a fatty acid having an alkyl or alkenyl group having 6 to 30 carbon atoms. 
     
     
         11 . The lubricating oil composition according to  claim 2 , wherein compound (D-2) is at least one selected from reaction products of an epoxide represented by the following formula: 
       
         
           
           
               
               
           
         
         wherein R1, R2, R3, and R4 each independently represent a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms, and at least one of R1, R2, R3, and R4 is a hydrocarbon group, 
         with boric acid or boron oxide, or ring-opened products thereof. 
       
     
     
         12 . The lubricating oil composition according to  claim 1 , further comprising (E) a metallic detergent. 
     
     
         13 . The lubricating oil composition according to  claim 1 , further comprising (F) an ether sulfolane compound. 
     
     
         14 . The lubricating oil composition according to  claim 1 , which is for a non-stage transmission. 
     
     
         15 . The lubricating oil composition according to  claim 2 , comprising, as a part or all of component (A), 5 to 30 percent by weight, based on a total weight of the lubricating oil composition, of a poly-α-olefin or α-olefin copolymer having a kinematic viscosity at 100° C. of 6 to 80 mm 2 /s, and further comprising (B) a polymethacrylate having a weight-average molecular weight of 15,000 to 40,000. 
     
     
         16 . The lubricating oil composition according to  claim 2 , wherein a part or all of component (C-1) and component (C-2) is a boronated succinimide compound. 
     
     
         17 . The lubricating oil composition according to  claim 16 , wherein each of component (C-1) and/or component (C-2) contains 0.1 to 3 percent by weight of boron, based on a weight of component (C-1) or component (C-2). 
     
     
         18 . The lubricating oil composition according to  claim 2 , wherein the weight ratio of component (C-1) to component (C-2), i.e., (C-2)/(C-1), is 1 to 10. 
     
     
         19 . The lubricating oil composition according to  claim 2 , wherein compound (D-1) is at least one selected from amide compounds derived from a fatty acid having an alkyl or alkenyl group having 6 to 30 carbon atoms. 
     
     
         20 . The lubricating oil composition according to  claim 3 , wherein compound (D-1) is at least one selected from amide compounds derived from a fatty acid having an alkyl or alkenyl group having 6 to 30 carbon atoms.