Hydraulic Composition with Improved Wear Properties

Abstract

The present invention relates to methods of lubricating a mechanical device by using a low sulfur lubricating composition that contains a friction modifier and provides improved antiwear performance. The invention further provides the lubricating compositions used therein.

1 . A method for lubricating a mechanical device requiring industrial fluids, hydraulic fluids, turbine oils, circulating oils, or combinations thereof, the method comprising:
 I. supplying the mechanical device with a lubricating composition comprising:
 (a) an oil of lubricating viscosity wherein the oil is substantially free of sulfur; and 
 (b) a friction modifier; 
   
       resulting in reduced wear, reduced friction, or combinations thereof within the device. 
     
     
         2 . The method of  claim 1  wherein component (a) comprises a group II oil, a group III oil, a gas-to-liquid oil, a poly-alpha-olefin, or combinations thereof, wherein component (a) has a sulfur content of less than 1000 ppm. 
     
     
         3 . The method of  claim 1  wherein the lubricating composition further comprises a dispersant, an antioxidant, a corrosion inhibitor, a carboxylic acid or anhydride, or combinations thereof. 
     
     
         4 . The method of  claim 1  wherein the lubricating composition further comprises a detergent, an antiwear agent, an antifoam, a metal deactivator, a demulsifier, a detergent stabilizer, or combinations thereof. 
     
     
         5 . The method of  claim 1  wherein the lubricating composition further comprises a metal di-hydrocarbyl-substituted dithiophosphate, wherein at least one hydrocarbyl group is a branched primary hydrocarbyl group. 
     
     
         6 . The method of  claim 1  wherein the lubricating composition further comprises a metal-free di-hydrocarbyl-substituted dithiophosphate, wherein at least one hydrocarbyl group is a branched primary hydrocarbyl group 
     
     
         7 . The method of  claim 1  wherein the mechanical device is a hydraulic system. 
     
     
         8 . The method of  claim 1  wherein component (b) comprises a fatty phosphite, a fatty acid amide, a fatty amine, a fatty acid, a fatty ester, a condensation product of a carboxylic acid or equivalent with a polyalkylene-polyamine and/or a polyol, a borated fatty amine, a borated fatty epoxide, a glycerol ester, a borated glycerol ester, a fatty imidazoline, a fatty oxazoline, a metal carboxylate, or combinations of two or more thereof. 
     
     
         9 . The method of  claim 1  wherein the amount of friction modifier in the lubricating composition is 0.03 to 1 wt % and wherein the method further results in improved demulsibility of the lubricating composition with water. 
     
     
         10 . The method of  claim 1  wherein the lubricating composition is prepared by adding the friction modifier as an aftermarket treatment to the oil of lubricating viscosity. 
     
     
         11 . A lubricating composition comprising:
 (a) an oil of lubricating viscosity wherein the oil is substantially free of sulfur;   (b) a friction modifier;   (c) a dispersant;   (d) a metal di-hydrocarbyl-substituted dithiophosphate, wherein at least one hydrocarbyl group is a branched primary hydrocarbyl group; and   (e) optionally a viscosity index improving polymer.   
     
     
         12 . A lubricating composition comprising:
 (a) an oil of lubricating viscosity wherein the oil is substantially free of sulfur;   (b) a friction modifier;   (c) a metal-free di-hydrocarbyl-substituted dithiophosphate, wherein at least one hydrocarbyl group is a branched primary hydrocarbyl group;   (d) an antioxidant; and   (e) optionally a viscosity index improving polymer   
     
     
         13 . The composition of  claim 11  wherein component (c) comprises a metal containing dispersant. 
     
     
         14 . The composition of  claim 11  wherein component (e) is a polymethacrylates polymer. 
     
     
         15 . The composition of  claim 11  wherein component (c) comprises a metal-free dispersant.