Star Polymer Lubricating Composition

Abstract

The invention provides a lubricating composition containing (a) 0.001 to 15 wt % of a polymer with (i) a weight average molecular weight of 50,000 to 1,000,000; and (ii) a shear stability index of 10 to 100; (b) an antiwear agent; (c) a corrosion inhibitor; and (d) an oil of lubricating viscosity. The invention further provides a method for lubricating a mechanical device with the lubricating composition.

1 - 35 . (canceled) 
     
     
         36 . A lubricating composition comprising:
 (a) about 0.1 to about 15 wt % of a polymer with radial or star architecture;   (b) an antiwear agent;   (c) a corrosion inhibitor; and   (d) an oil of lubricating viscosity.   
     
     
         37 . The lubricating composition of  claim 36 , wherein the shear stability index is about 20 to about 90. 
     
     
         38 . The lubricating composition of  claim 36 , wherein the polymer has a weight average molecular weight of about 100,000 to about 800,000. 
     
     
         39 . The lubricating composition of  claim 36 , wherein the lubricating composition further comprises a component of linear polymer chains. 
     
     
         40 . The lubricating composition of  claim 36 , wherein the polymer has a random, tapered, di-block, tri-block, or multi-block architecture. 
     
     
         41 . The lubricating composition of  claim 36 , wherein the polymer is obtained from RAFT or ATRP polymerisation processes. 
     
     
         42 . The lubricating composition of  claim 36 , wherein the polymer is a polymethacrylate, or mixtures thereof. 
     
     
         43 . The lubricating composition of  claim 42 , wherein the polymethacrylate is derived from a monomer composition comprising:
 (a) about 50 wt % to about 100 wt % of an alkyl methacrylate, wherein the alkyl group of the methacrylate has about 10 to about 20 carbon atoms;   (b) about 0 wt % to about 40 wt % of an alkyl methacrylate, wherein the alkyl group of the methacrylate has about Ito about 9 carbon atoms; and   (c) about 0 wt % to about 10 wt % of a nitrogen containing monomer.   
     
     
         44 . The lubricating composition of  claim 36 , wherein the polymer is present at about 0.075 to about 8 wt % of the lubricating composition. 
     
     
         45 . The lubricating composition of  claim 36 , wherein the antiwear agent is ash-containing. 
     
     
         46 . The lubricating composition of  claim 36 , wherein the antiwear agent is ashless. 
     
     
         47 . The lubricating composition of  claim 36 , wherein the antiwear agent comprises a metal dialkyldithiophosphate or a metal di alkylphosphate. 
     
     
         48 . The lubricating composition of  claim 36 , wherein the antiwear agent is present at about 0.0001 wt to about 5 wt % of the lubricating composition. 
     
     
         49 . The lubricating composition of  claim 36 , wherein the corrosion inhibitor comprises at least one of a benzotriazoles, or a 2,5-bis(alkyl-dithio)-1,3,4-thiadiazole. 
     
     
         50 . The lubricating composition of  claim 36 , wherein the corrosion inhibitor is present at 0.0001 wt % to about 5 wt %. 
     
     
         51 . The lubricating composition of  claim 36  further comprising a detergent, wherein the detergent comprises at least one of a phenate, sulphurised phenate or a sulphonate. 
     
     
         52 . The lubricating composition of  claim 51 , wherein the sulphonate contains a naphthalene ring. 
     
     
         53 . The lubricating composition of  claim 52 , wherein the sulphonate is present at about 0.001 to about 1.5 wt %. 
     
     
         54 . A method for lubricating a mechanical device comprising a supplying to the mechanical device a lubricating composition, wherein the mechanical device is hydraulic system, and wherein the lubricating composition comprises:
 (a) about 0.001 to about 15 wt % of a polymer with a weight average molecular weight of about 50,000 to about 1,000,000, wherein the polymer has radial or star architecture;   (b) an antiwear agent;   (c) a corrosion inhibitor; and   (d) an oil of lubricating viscosity.