Lubricant composition

Abstract

The present invention provides a lubricating oil composition containing a base oil (A), zinc dithiophosphate (B), a metal sulfonate (C), and an ashless friction modifier (D) containing a boronated alkenyl succinimide (D1), which is to be used for a machine equipped with at least one of a wet type brake and a wet type clutch. The lubricating oil composition is not only excellent in oxidation stability but also favorable in an effect for suppressing the generation of squeal and braking properties, and is suitably applicable to machines equipped with a wet type brake or wet type clutch.

1 : A lubricating oil composition, which is to be used for a machine equipped with at least one of a wet type brake and a wet type clutch, comprising a base oil (A), zinc dithiophosphate (B), a metal sulfonate (C), and an ashless friction modifier (D) containing a boronated alkenyl succinimide (D1). 
     
     
         2 : The lubricating oil composition according to  claim 1 , wherein the content of the component (B) as expressed in terms of a zinc atom based on the total amount of the lubricating oil composition is from 100 to 2,000 ppm by mass. 
     
     
         3 : The lubricating oil composition according to  claim 1 , wherein the content of the component (B) as expressed in terms of a zinc atom based on the total amount of the lubricating oil composition is from 500 to 1,500 ppm by mass. 
     
     
         4 : The lubricating oil composition according to  claim 1 , wherein the component (C) contains calcium sulfonate. 
     
     
         5 : The lubricating oil composition according to  claim 1 , wherein the content of the component (C) as expressed in terms of a metal atom based on the total amount of the lubricating oil composition is from 200 to 4,000 ppm by mass. 
     
     
         6 : The lubricating oil composition according to  claim 1 , wherein the content of the component (C) as expressed in terms of a metal atom based on the total amount of the lubricating oil composition is from 1,000 to 3,500 ppm by mass. 
     
     
         7 : The lubricating oil composition according to  claim 1 , wherein the content of a metal salicylate based on the total amount of the lubricating oil composition is less than 0.03% by mass. 
     
     
         8 : The lubricating oil composition according to  claim 1 , wherein the component (D1) is a boronated product of a compound represented by the following general formula (d-11) or (d-12): 
       
         
           
           
               
               
           
         
         wherein,
 R A , R A1 , and R A2  are each independently an alkenyl group having a weight average molecular weight (Mw) of 500 to 3,000; 
 R B , R B1 , and R B2  are each independently an alkylene group having 2 to 5 carbon atoms; and 
 x1 is an integer of 1 to 10, and x2 is an integer of 0 to 10. 
 
       
     
     
         9 : The lubricating oil composition according to  claim 1 , wherein a mass ratio [B/N] of a boron atom to a nitrogen atom constituting the component (D1) is from 0.2 to 3.0. 
     
     
         10 : The lubricating oil composition according to  claim 1 , wherein the content of the component (D1) as expressed in terms of a boron atom based on the total amount of the lubricating oil composition is from 30 to 600 ppm by mass. 
     
     
         11 : The lubricating oil composition according to  claim 1 , wherein the component (D) contains the component (D1) and an alkenyl group-containing unsaturated amine (D2). 
     
     
         12 : The lubricating oil composition according to  claim 11 , wherein a content ratio of the component (D1) to the component (D2) [(D1)/(D2)] is from 2 to 100 in terms of a mass ratio. 
     
     
         13 : The lubricating oil composition according to  claim 1 , wherein on the occasion of measuring a kinematic friction coefficient at an oil temperature of 80° C. under a load of 0.5 MPa by using a low-speed slip test apparatus in conformity with JASO M349, a ratio of a kinematic friction coefficient μ 1  at a rotational speed of 1 rpm to a kinematic friction coefficient μ 50  at a rotational speed of 50 rpm [μ 1 /μ 50 ] is 0.80 or more and less than 1.00. 
     
     
         14 : A machine equipped with at least one of a wet type brake and a wet type clutch, comprising the lubricating oil composition according to  claim 1 . 
     
     
         15 : A method of using a lubricating oil composition, comprising using the lubricating oil composition according to  claim 1  for a machine equipped with at least one of a wet type brake and a wet type clutch.