Lubricant composition for limiting friction

Abstract

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 being the reaction product of: a) at least one hydrophobic polymer subunit which comprises a hydrophobic polymer selected from polyolefins, polyacrylics and polystyrenes; b) at least one hydrophilic polymer subunit which comprises a hydrophilic polymer selected from polyethers, polyesters and polyamides; c) optionally at least one backbone moiety capable of linking polymeric subunits together; and d) optionally a chain termination group.

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 being the reaction product of:   a) at least one hydrophobic polymer subunit which comprises a hydrophobic polymer selected from polyolefins, polyacrylics and polystyrenes;   b) at least one hydrophilic polymer subunit which comprises a hydrophilic polymer selected from polyethers, polyesters and polyamides;   c) optionally at least one backbone moiety capable of linking polymeric subunits together; and   d) optionally a chain termination group.   
     
     
         2 . The composition according to  claim 1 , wherein the polymeric organic friction modifier has a weight average molecular weight of from 1000 to 30,000 Daltons. 
     
     
         3 . The composition according to  claim 1 , wherein the organic friction modifier is the reaction product of a functionalised polyolefin, a polyether, a polyol and a carboxylic acid end group. 
     
     
         4 . 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 from 1 to 10 carbon atoms; and   mixtures thereof.   
     
     
         5 . The composition according to  claim 1 , wherein the ester is selected from glycerol triheptanoate, triethylcitrate, tributylcitrate and mixtures thereof. 
     
     
         6 . 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   
     
     
         7 . 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 . 
     
     
         8 . The method according to  claim 7  for reducing the wear of parts 
     
     
         9 . 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 .