Lubricating compositions for transmissions

Abstract

A lubricating composition includes at least one base oil, at least one compound including a dithiocarbamate group, at least one compound including a phosphite group and at least one compound including a dithiophosphate group. The lubricating composition simultaneously has good anti-wear and extreme-pressure properties, a low coefficient of friction and good anti-seizing properties. The lubricating composition can be used for lubricating transmissions such as gearboxes, axles, preferably the manual gearboxes of motor vehicles.

1 . A lubricating composition comprising at least one base oil, at least one compound comprising a dithiocarbamate group, at least one compound comprising a phosphite group and at least one compound comprising a dithiophosphate group, the compound comprising a dithiocarbamate group being a mixture of:
  (a) at least one amine dithiocarbamate of general formula (I-c)   
       
         
           
           
               
               
           
         
         in which:
 R 8  and R 9  represent independently of each other hydrocarbon-containing groups, optionally substituted, comprising from 1 to 30 carbon atoms, 
 R 10 , R 11  and R 12  represent independently of each other a hydrogen atom or a hydrocarbon-containing group from 1 to 30 carbon atoms, it being understood that at least one of the R 10 , R 11  and R 12  groups is not a hydrogen atom; and 
 
          (b) at least one metal dithiocarbamate of general formula (I-e), 
       
       
         
           
           
               
               
           
         
         in which R 17  and R 18  represent independently of each other hydrocarbon-containing groups, optionally substituted, comprising from 1 to 30 carbon atoms, M represents a metal cation and n is the valency of this metal cation. 
       
     
     
         2 . The lubricating composition according to  claim 1  in which the compound comprising a dithiocarbamate group is a mixture of:
  (a) at least one amine dithiocarbamate of general formula (I-c) 
 
       
         
           
           
               
               
           
         
         in which:
 R 8  and R 9  represent independently of each other hydrocarbon-containing groups, optionally substituted, comprising from 1 to 30 carbon atoms, 
 R 10 , R 11  and R 12  represent independently of each other a hydrogen atom or a hydrocarbon-containing group from 1 to 30 carbon atoms, it being understood that at least one of the R 10 , R 11  and R 12  groups is not a hydrogen atom; and 
 
          (b) at least one metal dithiocarbamate of general formula (I-e-2), 
       
       
         
           
           
               
               
           
         
         in which R 17  and R 18  represent independently of each other linear alkyl hydrocarbon-containing groups. 
       
     
     
         3 . The lubricating composition according to  claim 2  in which R 17  and R 18  represent independently of each other linear alkyl groups comprising from 5 to 12 carbon atoms. 
     
     
         4 . The lubricating composition according to  claim 1  comprising from 0.1 to 5% by mass of compounds comprising a dithiocarbamate group, relative to the total mass of lubricating composition. 
     
     
         5 . The lubricating composition according to  claim 1  comprising from 0.1 to 3% by mass of the mixture of amine dithiocarbamate corresponding to formula (I-c) and metal dithiocarbamate corresponding to formula (I-e). 
     
     
         6 . The lubricating composition according to  claim 1  in which the compound comprising a phosphite group is selected from the phosphite monoesters, phosphite diesters or phosphite triesters, used alone or in a mixture. 
     
     
         7 . The lubricating composition according to  claim 6  in which the phosphite monoester has general formula (II-a) in its alcohol and/or ketone form, in which R 19  represents a hydrocarbon-containing group, optionally substituted, of 1 to 30 carbon atoms: 
       
         
           
           
               
               
           
         
       
     
     
         8 . The lubricating composition according to  claim 6  in which the phosphite diester has general formula (II-b) in its alcohol and/or ketone form, in which R 20  and R 21  represent independently of each other hydrocarbon-containing groups, optionally substituted, of 1 to 30 carbon atoms: 
       
         
           
           
               
               
           
         
       
     
     
         9 . The lubricating composition according to  claim 6  in which the phosphite triester has general formula (III-c) in which R 22 , R 23  and R 24  represent independently of each other hydrocarbon-containing groups, optionally substituted, comprising from 1 to 30 carbon atoms: 
       
         
           
           
               
               
           
         
       
     
     
         10 . The lubricating composition according to  claim 1  comprising from 0.1 to 5% by mass of compound comprising a phosphite group, relative to the total mass of lubricating composition. 
     
     
         11 . The lubricating composition according to  claim 1  in which the compound comprising a dithiophosphate group is selected from the group constituted by the ammonium dithiophosphates, amine dithiophosphates, dithiophosphate esters and metal dithiophosphates, used alone or in a mixture. 
     
     
         12 . The lubricating composition according to  claim 11  in which the ammonium dithiophosphate has general formula (III-a), in which R 25  and R 26  represent independently of each other hydrocarbon-containing groups, optionally substituted, comprising from 1 to 30 carbon atoms: 
       
         
           
           
               
               
           
         
       
     
     
         13 . The lubricating composition according to  claim 11  in which the amine dithiophosphate has general formula (III-b), in which R 27  and R 28  represent independently of each other hydrocarbon-containing groups, optionally substituted, comprising from 1 to 30 carbon atoms, R 29 , R 30  and R 31  represent independently of each other a hydrogen atom or a hydrocarbon-containing group from 1 to 30 carbon atoms, it being understood that at least one of the R 29 , R 30  and R 31  groups is not a hydrogen atom: 
       
         
           
           
               
               
           
         
       
     
     
         14 . The lubricating composition according to  claim 11  in which the dithiophosphate ester has general formula (III-c), in which R 33  and R 34  represent independently of each other hydrocarbon-containing groups, optionally substituted, comprising from 1 to 30 carbon atoms, R 35  and R 36  represent independently of each other hydrocarbon-containing groups comprising from 1 to 18 carbon atoms: 
       
         
           
           
               
               
           
         
       
     
     
         15 . The lubricating composition according to  claim 11  in which the metal dithiophosphate has general formula (III-d), in which R 37  and R 38  represent independently of each other hydrocarbon-containing groups, optionally substituted, comprising from 1 to 30 carbon atoms, M represents a metal cation and n is the valency of this metal cation: 
       
         
           
           
               
               
           
         
       
     
     
         16 . The lubricating composition according to  claim 1  comprising from 0.1 to 5% by mass of compound comprising a dithiophosphate group, relative to the total mass of lubricating composition. 
     
     
         17 . The lubricating composition according to  claim 1  also comprising an antioxidant selected from the group formed by the aromatic amines or phenol derivatives. 
     
     
         18 . The lubricating composition according to  claim 1  also comprising a dispersant derived from polyisobutene. 
     
     
         19 . The lubricating composition according to  claim 1  also comprising a polymethacrylate-type polymer. 
     
     
         20 . The lubricating composition according to  claim 1  having a kinematic viscosity at 100° C. according to the standard ASTM D445 comprised between 4 and 40 cSt. 
     
     
         21 . (canceled) 
     
     
         22 . A method of using a lubricating composition according to  claim 1  in order to reduce the fuel consumption of vehicles. 
     
     
         23 . A method for lubricating a transmission of a motor vehicle, the method comprising a step of bringing a lubricating composition into contact with the motor vehicle transmission, the lubricating composition comprising:
 at least one base oil, at least one compound comprising a dithiocarbamate group, at least one compound comprising a phosphite group and at least one compound comprising a dithiophosphate group, the compound comprising a dithiocarbamate group being a mixture of:    (a) at least one amine dithiocarbamate of general formula (I-c)   
       
         
           
           
               
               
           
         
         in which:
 R 8  and R 9  represent independently of each other hydrocarbon-containing groups, optionally substituted, comprising from 1 to 30 carbon atoms, 
 R 10 , R 11  and R 12  represent independently of each other a hydrogen atom or a hydrocarbon-containing group from 1 to 30 carbon atoms, it being understood that at least one of the R 10 , R 11  and R 12  groups is not a hydro en atom; and 
 
          (b) at least one metal dithiocarbamate of general formula (I-e), 
       
       
         
           
           
               
               
           
         
         in which R 17  and R 18  represent independently of each other hydrocarbon-containing groups, optionally substituted, comprising from 1 to 30 carbon atoms, M represents a metal cation and n is the valency of this metal cation. 
       
     
     
         24 . At least one compound comprising a dithiocarbamate group, at least one compound comprising a phosphite group and at least one compound comprising a dithiophosphate group in a base oil, at least one of the compounds comprising a dithiocarbamate group being a mixture of:
  (a) at least one amine dithiocarbamate of general formula (I-c)   
       
         
           
           
               
               
           
         
         in which
 R 8  and R 9  represent independently of each other hydrocarbon-containing groups, optionally substituted, comprising from 1 to 30 carbon atoms, 
 R 10 , R 11  and R 12  represent independently of each other a hydrogen atom or a hydrocarbon-containing group from 1 to 30 carbon atoms, it being understood that at least one of the R 10 , R 11  and R 12  groups is not a hydrogen atom; and 
 
          (b) at least one metal dithiocarbamate of general formula (I-e), 
       
       
         
           
           
               
               
           
         
         in which R 17  and R 18  represent independently of each other hydrocarbon-containing groups, optionally substituted, comprising from 1 to 30 carbon atoms, M represents a metal cation and n is the valency of this metal cation; 
          the compound improving wear, extreme-pressure, friction and anti-seizing properties of a lubricating composition.