Lubricating oil composition for buffers

Abstract

The present invention provides a lubricating oil composition for a shock absorber including: a base oil containing a mineral oil and/or a synthetic oil; (A) a phosphate compound and/or a phosphite compound having a hydrocarbon group having 2 to 18 carbon atoms; and (B) a secondary amine compound represented by the General Formula (I), wherein R 1 and R 2 each represent an alkyl group having 1 to 18 carbon atoms, an alkenyl group having 2 to 18 carbon atoms, or a cycloalkane-containing group having 5 to 18 carbon atoms, and R 1 and R 2 may be the same or different from each other, or may be bonded to each other to form a cyclic structure having 3 to 6 carbon atoms with a nitrogen atom serving as a hetero atom. The lubricating oil composition for a shock absorber of the present invention can increase the friction force between seals and steel parts in the shock absorber of an automobile, improve the control stability when the car is driven at high speeds, and simultaneously improve the ride quality.

1 . A lubricating oil composition for a shock absorber, comprising:
 a base oil containing a mineral oil and/or a synthetic oil;   (A) a phosphate compound and/or a phosphite compound having a hydrocarbon group having 2 to 18 carbon atoms; and   (B) a secondary amine compound represented by General Formula (I),   
     
       
         
         
             
             
         
       
     
     wherein R 1  and R 2  each represent an alkyl group having 1 to 18 carbon atoms, an alkenyl group having 2 to 18 carbon atoms, or a cycloalkane-containing group having 5 to 18 carbon atoms, and R 1  and R 2  may be the same or different from each other, or may be bonded to each other to form a cyclic structure having 3 to 6 carbon atoms with a nitrogen atom serving as a hetero atom. 
   
   
       2 . A lubricating oil composition for a shock absorber according to  claim 1 , wherein the phosphate compound having a hydrocarbon group having 2 to 18 carbon atoms is acid phosphate having one or two hydrocarbon groups. 
   
   
       3 . A lubricating oil composition for a shock absorber according to  claim 1 , wherein the phosphite compound having a hydrocarbon group having 2 to 18 carbon atoms is acid diphosphite having two hydrocarbon groups. 
   
   
       4 . A lubricating oil composition for a shock absorber according to  claim 1 , wherein a blending amount of the phosphate compound and/or the phosphite compound (A) is 0.01 to 4% by mass based on a total amount of the composition. 
   
   
       5 . A lubricating oil composition for a shock absorber according to  claim 1 , wherein a blending amount of the secondary amine compound (B) is 0.05 to 5% by mass based on a total amount of the composition. 
   
   
       6 . A lubricating oil composition for a shock absorber according to  claim 1 , further comprising at least one member selected from an ash-less detergent-dispersant, a metal-based detergent, a lubricity improver, an antioxidant, a rust preventive agent, a metal deactivator, a viscosity index improver, a pour point depressant, and an antifoaming agent.