Lubricating oil composition for internal combustion engine

Abstract

A lubricating oil composition for internal combustion engine, comprising a lubricating base oil; (A) a triphosphate represented by formula (1) below in an amount of 0.01 to 0.2 percent by mass in terms of phosphorus; (B) succinimide and/or derivative thereof in an amount of 0.01 to 0.3 percent by mass in terms of nitrogen; (C) an alkali metal or alkaline earth metal detergent in an amount of 0.05 to 1 percent by mass in terms of metal; and (D) a phenol-based and/or amine-based anti-oxidants in an amount of 0.01 to 3 percent by mass: O═P(OR 1 ) 3   (1) wherein the groups of R 1 are each independently a hydrocarbon group having 1 to 30 carbon atoms and are the same or different from each other. The lubricating oil composition is excellent in anti-wear properties, base number retaining properties, high temperature detergency, and low friction characteristics.

1 . A lubricating oil composition for internal combustion engine, comprising a lubricating base oil; (A) a triphosphate represented by formula (1) below in an amount of 0.01 to 0.2 percent by mass in terms of phosphorus; (B) succinimide and/or derivative thereof in an amount of 0.01 to 0.3 percent by mass in terms of nitrogen; (C) an alkali metal or alkaline earth metal detergent in an amount of 0.05 to 1 percent by mass in terms of metal; and (D) a phenol-based and/or amine-based anti-oxidants in an amount of 0.01 to 3 percent by mass:  
       O═P(OR 1 ) 3    (1)  
       wherein the groups of R 1  are each independently a hydrocarbon group having 1 to 30 carbon atoms and are the same or different from each other.  
     
     
         2 . The lubricating oil composition for internal combustion engine according to  claim 1  wherein said alkali metal or alkaline earth metal detergent contains an alkali metal or alkaline earth metal salicylate detergent.  
     
     
         3 . The lubricating oil composition for internal combustion engine according to  claim 2  wherein said alkali metal or alkaline earth metal salicylate detergent is an alkali metal or alkaline earth metal salicylate detergent whose metal ratio represented by “valence of metal element×metal element content (mol)/soap group content (mol)” is 3 or less.  
     
     
         4 . The lubricating oil composition for internal combustion engine according to  claim 2  wherein said alkali metal or alkaline earth metal detergent is a mixture of an alkali metal or alkaline earth metal salicylate detergent whose metal ratio represented by “valence of metal element×metal element content (mol)/soap group content (mol)” is 1.5 or less and an alkali metal or alkaline earth metal salicylate detergent whose metal ratio is more than 1.5.  
     
     
         5 . The lubricating oil composition for internal combustion engine according to  claim 2  wherein said alkali metal or alkaline earth metal detergent is a mixture of an alkali metal or alkaline earth metal salicylate detergent whose metal ratio represented by “valence of metal element×metal element content (mol)/soap group content (mol)” is 1.5 or less and an alkali metal or alkaline earth metal sulfonate detergent.  
     
     
         6 . The lubricating oil composition for internal combustion engine according to  claim 1  which contains a sulfur-containing anti-wear agent in an amount of 0.1 percent by mass or less in terms of sulfur.  
     
     
         7 . The lubricating oil composition for internal combustion engine according to  claim 1  which contains a lubricating base oil whose aromatic content is 3 percent by mass or less and sulfur content is 50 ppm by mass or less.  
     
     
         8 . The lubricating oil composition for internal combustion engine according to  claim 1  which is used in an internal combustion engine using a fuel whose sulfur content is 50 ppm by mass or less.  
     
     
         9 . The lubricating oil composition for internal combustion engine according to any one of  claim 1  which is used in gas engines.