Lubricating oil composition

Abstract

Disclosed is a lubricating oil composition capable of inhibiting vibrations or noises generated between a pulley and a chain or between a pulley and a belt in a CVT or the like, while increasing an intermetallic friction coefficient, the composition containing a base oil, an alkaline earth metal-based detergent (A), a phosphite ester (B 1 ), a phosphate ester amine salt (B 2 ), an acidic phosphate ester (B 3 ), an aliphatic monoamine (C 1 ), and an aromatic monoamine (C 2 ).

1 . A lubricating oil composition, comprising:
 a base oil;   (A) an alkaline earth metal-based detergent (A);   (B1) a phosphite ester (B1);   (B2) a phosphate ester amine salt (B2);   (B3) an acidic phosphate ester (B3);   (C1) an aliphatic monoamine (C1); and   (C2) an aromatic monoamine (C2).   
     
     
         2 . The lubricating oil composition according to  claim 1 , wherein the phosphite ester (B1) is a compound represented by the following formula (I):
   ( R   1 O) a P(OH) 3−a   (I)
   
       wherein:
 R 1  represents a hydrocarbon group having 2 to 24 carbon atoms; 
 a represents an integer of 1 to 3; and 
 when a is 2 or 3, R 1 's may be the same as or different from each other. 
 
     
     
         3 . The lubricating oil composition according to  claim 2 , wherein in the formula (I);
 a is 2, and   R 1  is an aliphatic hydrocarbon group having 8 to 20 carbon atoms.   
     
     
         4 . The lubricating oil composition according to  claim 1   2 , wherein the phosphate ester amine salt (B2) is an amine salt of an acidic phosphate ester represented by the following formula (II):
   ( R   2 O) b P(=O)(OH) 3−b   (II)
   
       wherein:
 R 2  represents a hydrocarbon group having 2 to 24 carbon atoms; 
 b represents an integer of 1 or 2; and 
 when b is 2, R 2 's may be the same as or different from each other. 
 
     
     
         5 . The lubricating oil composition according to  claim 4 , wherein in the formula (II), R 2  is an aliphatic hydrocarbon group having 8 to 20 carbon atoms. 
     
     
         6 . The lubricating oil composition according to  claim 1 , wherein the acidic phosphate ester (B3) is a compound represented by the following formula (III):
   ( R   3 O) c P(=O)(OH) 3−c   (III)
   
       wherein:
 R 3  represents a hydrocarbon group having 2 to 24 carbon atoms; 
 c represents an integer of 1 or 2; and 
 when c is 2, R 3 's may be the same as or different from each other. 
 
     
     
         7 . The lubricating oil composition according to  claim 6 , wherein in the formula (III), R 3  is an aliphatic hydrocarbon group having 8 to 20 carbon atoms. 
     
     
         8 . The lubricating oil composition according to  claim 1 , wherein the aliphatic monoamine (C1) is a compound represented by the following formula (IV):
     NR   4   R   5   R   6   (IV)
   
       wherein:
 R 4  represents an aliphatic hydrocarbon group having 10 to 24 carbon atoms; 
 R 5  and R 6  each represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms; and 
 R 5  and R 6  may be the same as or different from each other. 
 
     
     
         9 . The lubricating oil composition according to  claim 8 , wherein in the formula (IV);
 R 4  is an aliphatic hydrocarbon group having 12 to 18 carbon atoms, and   R 5  and R 6  are each a hydrogen atom or an alkyl group having 1 to 2 carbon atoms.   
     
     
         10 . The lubricating oil composition according to  claim 1 , wherein the aromatic monoamine (C2) is a compound represented by the following formula (V):
     NR   7   R   8   R   9   (V)
   
       wherein:
 R 7  represents an aromatic hydrocarbon group having 6 to 12 carbon atoms; 
 R 8  and R 9  each represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms; and 
 R 8  and R 9  may be the same as or different from each other. 
 
     
     
         11 . The lubricating oil composition according to  claim 1 , wherein a base number of the alkaline earth metal-based detergent (A) is from 10 to 500 mg KOH/g. 
     
     
         12 . The lubricating oil composition according to  claim 1 , wherein the amount of the alkaline earth metal atom derived from the alkaline earth metal-based detergent (A) is from 10 to 1,500 ppm by mass on the basis of the whole amount of the lubricating oil composition. 
     
     
         13 . The lubricating oil composition according to  claim 1 , wherein a sum total of the amounts of the phosphorus atom derived from the components (B1) to (B3) is from 10 to 1,000 ppm by mass on the basis of the whole amount of the lubricating oil composition. 
     
     
         14 . The lubricating oil composition according to  claim 1 , wherein a sum total of the amounts of the nitrogen atom derived from the components (C1) to (C2) is from 100 to 3,000 ppm by mass on the basis of the whole amount of the lubricating oil composition. 
     
     
         15 . A method for producing a lubricating oil composition, the method comprising blending a base oil with at least an alkaline earth metal-based detergent (A), a phosphite ester (B1), a phosphate ester amine salt (B2), an acidic phosphate ester (B3), an aliphatic monoamine (C1), and an aromatic monoamine (C2), to obtain a lubricating oil composition.