Lubricant composition for limiting friction

Abstract

The present application relates to a lubricant composition comprising, in relation to the total weight of the lubricant composition at least one base oil; 0.005 to 10% by weight of at least one polymeric organic friction modifier; and 0.005 to 10% by weight of at least one ester said polymeric organic friction modifier is a compound of formula (I):R1.[(AO)n.-AO—R2]m   (I)wherein R1 is a residue of a group having at least m hydrogen atoms, m being greater than 2;AO is an alkylene oxide residue;n is between 0 and 100;R2 is a hydrogen atom or a C—(O)—R3 group with R3 being a residue.

1 . A lubricant composition comprising, based on the total weight of lubricant composition:
 at least one base oil;   0.005 to 10% by weight of at least one polymeric organic friction modifier; and   0.005 to 10% by weight of at least one ester which is a product of the esterification reaction between a saturated or unsaturated, linear, cyclic or branched monohydric alcohol having 1 to 10 carbon atoms and a carboxylic polyacid or between a linear, cyclic or branched polyol and a saturated or unsaturated, linear, cyclic or branched monocarboxylic acid having between 1 and 10 carbon atoms,   said polymeric organic friction modifier is a compound of formula (I):
   R 1 .[(AO) n .-AOR 2 ] m    (I)
 
   wherein R 1  is a residue of a group having at least m hydrogen atoms, m being greater than 2;   AO is an alkylene oxide residue;   n is between 0 and 100;   R 2  is a hydrogen atom or a C—(O)—R 3  group with R 3  being a residue selected from the list consisting of a polyhydroxyalkyl carboxylic acid residue, a polyhydroxyalkenyl carboxylic acid residue, a hydroxyalkyl carboxylic acid residue, a hydroxyalkenyl carboxylic acid residue, a hydroxyalkyl carboxylic acid oligomer residue and a hydroxyalkenyl carboxylic acid oligomer residue; and   in which on average at least two R 2  groups are acyls.   
     
     
         2 . The composition according to  claim 1 , wherein the polymeric organic friction modifier has a weight average molecular weight of from 3,000 to 8,000 Daltons. 
     
     
         3 . The composition according to  claim 1 , wherein the ester is selected from:
 a triester of glycerol and of a monocarboxylic acid having from 1 to 10 carbon atoms; and   a triester of citric acid and of a monohydric alcohol having 1 to 10 carbon atoms; and   mixtures thereof.   
     
     
         4 . The composition according to  claim 1 , wherein the ester is selected from glycerol triheptanoate, triethylcitrate, tributylcitrate and mixtures thereof. 
     
     
         5 . The composition according to  claim 1 ,
 at least 50% by weight of one or more base oils;   from 0.005 a 10% by weight of one or more polymeric organic friction modifiers;   from 0.005 to 10% by weight of one or more esters selected from glycerol esters, citric acid esters, tartaric acid esters and mixtures thereof;   optionally from 0.005 to 30% by weight of one or more functional additives other than polymeric organic friction modifiers and glycerol esters, citric acid esters and tartaric acid esters.   
     
     
         6 . A method for reducing friction between two mechanical parts comprising one step of bringing the two mechanical parts into contact with the lubricating composition according to  claim 1 . 
     
     
         7 . The method according to  claim 6  for reducing the wear of parts. 
     
     
         8 . A method for lubricating mechanical parts comprising at least one step of bringing a part into contact with the lubricating composition according to  claim 1 .