Antiwear composition and method of lubricating driveline device

Abstract

The present invention relates to an antiwear agent and lubricating compositions thereof. The invention further provides for a method of lubricating a driveline device application by employing a lubricating composition containing the antiwear agent.

What is claimed is: 
     
         1 . A method for lubricating a driveline device comprising supplying to the driveline device a lubricating composition comprising an oil of lubricating viscosity and an antiwear package wherein the antiwear package comprises
 (a) 0.01 wt % to 3 wt % of a derivative of a hydroxycarboxylic acid, wherein the derivative of a hydroxycarboxylic acid is represented by the formula:   
       
         
           
           
               
               
           
         
       
       wherein 
       n=2, m=1, or 
       n and m both equal 2, or 
       n=3, m=1; 
       X is an aliphatic or alicyclic group, or an aliphatic or alicyclic group containing an oxygen atom in the carbon chain, or a substituted group of the foregoing types, said group containing up to 6 carbon atoms and having n+m available points of attachment; 
       each Y is independently —O—; and 
       each R and R 1  are independently hydrogen or a hydrocarbyl group, provided that at least one R or R 1  group is a hydrocarbyl group; each R 2  is independently hydrogen, a hydrocarbyl group or an acyl group, further provided that at least one —OR 2  group is located on a carbon atom within X that is α or β to at least one of the —C(O)—Y—R groups, and
 (b) 0.05 wt % to 2 wt % of a phosphorus compound, wherein the phosphorus compound is an amine salt of a phosphate hydrocarbon ester represented by the formula: 
 
       
         
           
           
               
               
           
         
       
       wherein 
       R 3  and R 4  are independently hydrogen or hydrocarbon containing 8 to 18 carbon atoms, with the proviso that at least one is a hydrocarbon group; and
 R 5 , R 6 , R 7  and R 8  independently hydrogen or a hydrocarbyl group, with the proviso that at least one is a hydrocarbyl group. 
 
     
     
         2 . The method of  claim 1 , wherein the hydroxy-carboxylic acid is tartaric acid or citric acid. 
     
     
         3 . The method of  claim 1 , wherein the hydroxy-carboxylic acid is present at 0.01 wt % to 1 wt % of the lubricating composition. 
     
     
         4 . The method of  claim 1 , wherein the hydroxy-carboxylic acid is present at 0.1 wt % to 0.2 wt % of the lubricating composition. 
     
     
         5 . The method of  claim 1 , wherein the phosphorus compound is a mixture of an amine salt of a phosphate hydrocarbon ester, and a phosphite having at least one hydrocarbyl group with 4 or more carbon atoms. 
     
     
         6 . The method of  claim 5 , wherein the phosphite is a mono-hydrocarbyl substituted phosphite, a di-hydrocarbyl substituted phosphite, or a tri-hydrocarbyl substituted phosphite. 
     
     
         7 . The method of  claim 5 , wherein the phosphite having at least one hydrocarbyl group with 4 or more carbon atoms is represented by the formulae: 
       
         
           
           
               
               
           
         
         wherein at least two of R 9 , R 10  and R 11  may be a hydrocarbyl group containing at least 4 carbon atoms and the other may be hydrogen or a hydrocarbyl group. 
       
     
     
         8 . The method of  claim 1 , wherein the phosphorus compound is present at 0.1 wt % to 1 wt % of the lubricating composition. 
     
     
         9 . The method of  claim 1 , wherein the phosphorus compound is present at 0.2 wt % to 0.4 wt % of the lubricating composition. 
     
     
         10 . The method of  claim 1  further comprising 0.1 wt % to 5 wt % of a borated polyisobutylene succinimide, or a dimercaptothiadiazole derivative of a polyisobutylene succinimide. 
     
     
         11 . The method of  claim 1 , wherein
 (a) the derivative of a hydroxycarboxylic acid is present at 0.01 wt % to 1 wt % of the lubricating composition; and   (b) wherein the phosphorus compound is present at 0.05 wt % to 2 wt % of the lubricating composition.   
     
     
         12 . The method of  claim 1 , wherein
 (a) the derivative of a hydroxycarboxylic acid is present at 0.05 wt % to 0.5 wt % of the lubricating composition; and   (b) wherein the phosphorus compound is present at 0.1 wt % to 1 wt % of the lubricating composition.