Star Polymer Lubricating Composition

Abstract

The invention provides a lubricating composition containing (a) 0.001 wt % to 15 wt % of a polymer with radial or star architecture; (b) an overbased detergent; (c) a dispersant; and (d) an oil of lubricating viscosity. The invention further provides a method for lubricating a mechanical device with the lubricating composition.

1 . A lubricating composition comprising:
 (a) 0.001 wt % to 15 wt % of a polymer with radial or star architecture, wherein the polymer is a polymethacrylate, or mixtures thereof;   (b) an overbased detergent;   (c) a dispersant; and   (d) an oil of lubricating viscosity.   
   
   
       2 . The lubricating composition of  claim 1 , wherein the polymer contains 70 wt % or more of a mono-vinyl monomer. 
   
   
       3 . The lubricating composition of  claim 1 , wherein the polymer has a weight average molecular weight of 300,000 to 1,000,000. 
   
   
       4 . The lubricating composition of  claim 1 , wherein the polymer is a copolymer. 
   
   
       5 . The lubricating composition of  claim 1 , wherein the lubricating composition further comprises a portion of linear polymer chains. 
   
   
       6 . The lubricating composition of  claim 1 , wherein the polymer comprises arms with random, tapered, di-block, tri-block, or multi-block architecture. 
   
   
       7 .- 8 . (canceled) 
   
   
       9 . The lubricating composition of  claim 1 , wherein the polymer is obtained from RAFT or ATRP polymerisation processes. 
   
   
       10 .- 12 . (canceled) 
   
   
       13 . The lubricating composition of  claim 1 , wherein the polymethacrylate is derived from a monomer composition comprising:
 (a) 50 wt % to 100 wt % of an alkyl methacrylate, wherein the alkyl group of the methacrylate has 10 to 20 carbon atoms;   (b) 0 wt % to 40 wt % of an alkyl methacrylate, wherein the alkyl group of the methacrylate has 1 to 9 carbon atoms; and   (c) 0 wt % to 10 wt % of a nitrogen containing monomer.   
   
   
       14 . The lubricating composition of  claim 1 , wherein the polymer is present at 0.01 to 12 wt %, or 0.075 to 8 wt % of the lubricating composition. 
   
   
       15 . (canceled) 
   
   
       16 . The lubricating composition of  claim 1 , wherein the overbased detergent comprises one or more of salixarates, phenates, sulphonates, or salicylates. 
   
   
       17 .- 18 . (canceled) 
   
   
       19 . The lubricating composition of  claim 1 , wherein the dispersant comprises one or more of succinimide dispersants. 
   
   
       20 . (canceled) 
   
   
       21 . The lubricating composition of  claim 1  further comprising an antiwear agent. 
   
   
       22 . The lubricating composition of  claim 21 , wherein the antiwear agent comprises a metal dialkyldithiophosphate. 
   
   
       23 . The lubricating composition of  claim 1  further comprising an anti-oxidant. 
   
   
       24 . The lubricating composition of  claim 23 , wherein the antioxidant is selected from the group consisting of sulphurised olefins, alkylated diphenylamines, hindered phenols, molybdenum compounds, and mixtures thereof. 
   
   
       25 . The lubricating composition of  claim 24 , wherein the antioxidant is a molybdenum compound, an alkylated diphenylamine or a hindered phenol. 
   
   
       26 .- 29 . (canceled) 
   
   
       30 . The lubricating composition of  claim 1 , wherein the lubricating composition has a (i) a sulphur content of 0.5 wt % or less, (ii) a phosphorus content of 0.1 wt % or less, and (iii) a sulphated ash content of 1.5 wt % or less. 
   
   
       31 . The lubricating composition of  claim 1 , wherein the lubricating composition has a SAE viscosity grade from XW-Y, where X is an integer from 0 to 20 and Y is an integer from 20 to 50. 
   
   
       32 . The lubricating composition of  claim 1 , wherein the lubricating composition contains:
 (b) 0.1 wt % to 15 wt % of an overbased detergent;   (c) 0.1 wt % to 25 wt % of a dispersant; and   (e) 45 wt % to 99.7 wt % of an oil of lubricating viscosity.   
   
   
       33 . A method for lubricating an internal combustion engine comprising supplying to the internal combustion engine a lubricating composition, wherein the lubricating composition comprises:
 (a) 0.001 wt % to 15 wt % of a polymer with radial or star architecture;   (b) an overbased detergent;   (c) a dispersant; and   (d) an oil of lubricating viscosity.