Lubricant composition with improved cold stability and fuel-economy properties

Abstract

The invention relates to a lubricant composition comprising at least: a base oil, a friction modifier comprising molybdenum, a boron-containing dispersant, a polymer comprising repeating units which can be obtained by polymerization of monomers (a) with the formula (I): wherein: R1 represents a hydrogen atom or a methyl moiety, X1 represents a moiety chosen from: —O—, —O(AO)m, or —NH—, each moiety A independently representing a C2-C4 alkylene moiety and m represents an integer from 0 to 10. R2 is a polybutylene moiety, and p is equal to 0 or 1.

1 . A lubricant composition comprising:
 at least one base oil,   at least one friction modifier comprising molybdenum, such that the amount of molybdenum in the lubricant composition ranges from 100 ppm to 1,500 ppm by weight, with respect to the total weight of the lubricant composition,   at least one boron-containing dispersant, such that the amount of boron in the lubricant composition ranges from 10 ppm to 300 ppm, with respect to the total weight of the lubricant composition,   from 0.1% to 10% by weight of dry matter, with respect to the total weight of the lubricant composition, of a polymer comprising repeating units which could be obtained by polymerization of monomers (a) with the formula (I):   
       
         
           
           
               
               
           
         
         wherein: 
         R 1  represents a hydrogen atom or a methyl moiety, 
         X 1  represents a moiety chosen from: —O—, —O(AO)m, or —NH—, each moiety A independently representing a C2-C4 alkylene moiety and m represents an integer ranging from 0 to 10, 
         R 2  is a polybutylene moiety, and 
         p is 0 or 1. 
       
     
     
         2 . The lubricant composition according to  claim 1 , comprising:
 at least 50% by weight, with respect to the total weight of the lubricant composition, of one or several base oils,   from 0.01% to 10% by weight, with respect to the total weight of the lubricant composition, of one or several friction modifiers comprising molybdenum, such that the amount of molybdenum in the lubricant composition ranges from 300 ppm to 1,000 ppm by weight, with respect to the total weight of the lubricant composition,   from 0.01% to 10% by weight, with respect to the total weight of the lubricant composition, of one or several boron-containing dispersants, such that the amount of boron in the lubricant composition ranges from 10 ppm to 300 ppm by weight, with respect to the total weight of the lubricant composition,   from 0.5% to 5% by weight of dry matter, with respect to the total weight of the lubricant composition, of a copolymer which can be obtained by copolymerization of monomers (a) with the formula (I) and monomers (b) with the formula (II):   
       
         
           
           
               
               
           
         
         wherein: 
         R 3  represents a hydrogen atom or a methyl moiety, 
         X 2  is a —O— or —NH— moiety, 
         R 4  moieties independently represent a C2-C4 alkylene moiety, 
         R 5  represents a C1-C8 alkyl moiety, and 
         q is an integer ranging from 1 to 20. 
       
     
     
         3 . The lubricant composition according to  claim 1 , comprising:
 at least 70% by weight, with respect to the total weight of the lubricant composition, of one or a plurality of base oils,   from 0.01% to 5% by weight, with respect to the total weight of the lubricant composition, of one or several friction modifiers comprising molybdenum, such that the amount of molybdenum in the lubricant composition ranges from 500 ppm to 1,000 ppm by weight, with respect to the total weight of the lubricant composition,   from 0.01% to 5% by weight, with respect to the total weight of the lubricant composition, of one or several boron-containing dispersants, such that the amount of boron in the lubricant composition ranges from 20 ppm to 300 ppm by weight, with respect to the total weight of the lubricant composition,   from 0.8% to 3% by weight of dry matter, with respect to the total weight of the lubricant composition, of a copolymer comprising, with respect to the total weight of the copolymer:
 from 1% to 50% by weight of units derived from monomers (a), and 
 from 1% to 80% by weight of units derived from monomers (b). 
   
     
     
         4 . The lubricant composition according to  claim 1 , having a kinematic viscosity at 100° C., measured according to ASTM D445, ranging from 3.8 mm2/s to 21.9 mm2/s. 
     
     
         5 . The lubricant composition according to  claim 1 , wherein the friction modifier comprising molybdenum is an organomolybdenum compound. 
     
     
         6 . The lubricant composition according to  claim 1 , wherein the boron dispersant is chosen from boron succinimides. 
     
     
         7 . A use, in a lubricant composition comprising a base oil, one or several molybdenum friction modifiers and one or several boron dispersants, of a copolymer comprising repeating units which can be obtained by polymerizing monomers (a) with the formula (I): 
       
         
           
           
               
               
           
         
         wherein: 
         R 1  represents a hydrogen atom or a methyl moiety, 
         X 1  represents a moiety chosen from: —O—, —O(AO)m, or —NH—, each moiety A independently representing a C2-C4 alkylene moiety and m represents an integer from 0 to 10, 
         R 2  is a polybutylene moiety, and 
         p is 0 or 1, 
         for improving the cold stability of said lubricant composition. 
       
     
     
         8 . (canceled) 
     
     
         9 . (canceled) 
     
     
         10 . (canceled) 
     
     
         11 . The lubricant composition according to  claim 5 , wherein the friction modifier comprising molybdenum is chosen from a molybdenum dithiocarbamate derivative (MoDTC), a molybdenum dithiophosphate derivative (MoDTP) or a sulfur-free molybdenum complex. 
     
     
         12 . The lubricant composition according to  claim 5 , wherein the friction modifier comprising molybdenum is a molybdenum dithiocarbamate derivative (MoDTC). 
     
     
         13 . The lubricant according to  claim 6 , wherein the boron dispersant is chosen from boron polyisobutene succinimides. 
     
     
         14 . A method for lubricating at least one part of an engine, said method comprising bringing at least one part of the engine into contact with a lubricant composition according to  claim 1 . 
     
     
         15 . The method according to  claim 14 , for reducing friction occurring within said engine. 
     
     
         16 . A method for improving the fuel economy (FE) properties and/or the cold stability properties of a lubricant composition, said method comprising adding to said lubricant composition a combination of:
 a) at least one polymer comprising repeating units which could be obtained by polymerization of monomers (a) with the formula (I):   
       
         
           
           
               
               
           
         
          wherein:
 R 1  represents a hydrogen atom or a methyl moiety, 
 X 1  represents a moiety chosen from: —O—, —O(AO)m, or —NH—, each moiety A independently representing a C2-C4 alkylene moiety and m represents an integer ranging from 0 to 10, 
 
         R 2  is a polybutylene moiety, and 
         p is 0 or 1, 
         b) at least one friction modifier comprising molybdenum, such that the amount of molybdenum in the lubricant composition ranges from 100 ppm to 1,500 ppm by weight, with respect to the total weight of the lubricant composition, and 
         c) at least one boron-containing dispersant, such that the amount of boron in the lubricant composition ranges from 10 ppm to 300 ppm, with respect to the total weight of the lubricant composition.