Lubricant composition

Abstract

The present invention provides a lubricating composition, particularly a grease composition and a lubricating oil composition, containing an aralkylated diphenylamine and a phenol compound having a molecular weight of not less than 340 which are compounded into a base oil. The lubricating composition is hardly decomposed or volatilized even at high temperatures and has a long oxidation life so that the lubricating characteristics thereof can be maintained for a long period of time.

1 . A lubricating composition comprising a base oil, an aralkylated diphenylamine, and a phenol compound having a molecular weight of not less than 340. 
   
   
       2 . A lubricating composition as recited in  claim 1 , wherein the phenol compound has a molecular weight not less than 340 but not greater than 1,500. 
   
   
       3 . A lubricating composition as recited in  claim 1  or  2 , wherein the base oil has a flash point of not lower than 180° C. and wherein the lubricating composition is a grease composition which additionally comprises a thickening agent. 
   
   
       4 . A lubricating composition as recited in  claim 3 , which contains 0.01 to 10% by mass of the aralkylated diphenylamine, 0.01 to 10% by mass of the phenol compound having a molecular weight of not less than 340 and 10 to 30% by mass of the thickening agent, based on the grease composition. 
   
   
       5 . A lubricating composition as recited in  claim 1  or  2 , which is a lubricating oil composition and contains 0.01 to 10% by mass of the aralkylated diphenylamine and 0.01 to 10% by mass of the phenol compound having a molecular weight of not less than 340, based on the lubricating oil composition. 
   
   
       6 . A lubricating composition as recited in any one of  claims 1  to  5 , wherein the aralkylated diphenylamine is represented by the following chemical formula (1): 
     
       
         
         
             
             
         
       
     
     wherein R 1  and R 4  each independently represent a C 0  to C 24  alkyl group and R 2  and R 3  each independently represent a C 1  to C 5  alkylene group. 
   
   
       7 . A lubricating composition as recited in any one of  claims 1  to  6 , wherein the phenol compound having a molecular weight of not less than 340 is represented by the following chemical formula (2): 
     
       
         
         
             
             
         
       
     
     wherein R 5  represents a C 1  to C 18  alkyl group, R 6  represents a C 1  to C 5  alkylene group, R 7  represents a C 1  to C 24  alkyl group and n is 1 or 2. 
   
   
       8 . A lubricating composition as recited in any one of  claims 1  to  6 , wherein the phenol compound having a molecular weight of not less than 340 is a bisphenol compound. 
   
   
       9 . A lubricating composition as recited in  claim 3 ,  4 ,  6 ,  7  or  8 , wherein the thickening agent is a complex soap or a urea compound. 
   
   
       10 . A lubricating composition as recited in any one of  claims 3  to  8 , wherein the base oil has a flash point of not less than 200° C. 
   
   
       11 . A lubricating composition as recited in  claim 1 ,  2 ,  3 ,  4 ,  6 ,  7 ,  8  or  9 , which has a dropping point of not less than 230° C.