Lubricating Composition Containing Ashfree Antiwear Agent Based on Hydroxypolycarboxylic Acid Derivative and a Molybdenum Compound

Abstract

The invention provides a lubricating composition containing an oil of lubricating viscosity, an oil soluble molybdenum compound, and an ashless antiwear agent. The invention further provides for a new antioxidant. The lubricating composition is suitable for lubricating an internal combustion engine.

1 . A lubricating composition comprising an oil of lubricating viscosity, an oil-soluble molybdenum compound, and an ashless antiwear agent represented by Formula (1): 
     
       
         
         
             
             
         
       
     
     wherein
 Y and Y′ are independently —O—, >NH, >NR 3 , or an imide group formed by taking together both Y and Y′ groups and forming a R 1 —N<group between two >C═O groups; 
 X is independently —Z—O—Z′—, >CHR 4 , >CR 4 R 5 , >C(OH)(CO 2 R 2 ), >C(CO 2 R 2 ) 2 , >CCH 2 CO 2 R 2  or >CHOR 6 ; 
 Z and Z′ are independently >CH 2 , >CHR 4 , >CR 4 R 5 , >C(OH)(CO 2 R 2 ), or >CHOR 6 ; 
 n is 0 to 10, with the proviso that when n=1, X is not >CH 2 , and when n=2, both X′ s are not simultaneously >CH 2 ; 
 m is 0 or 1; 
 R 1  is independently hydrogen or a hydrocarbyl group, typically containing 1 to 150 carbon atoms, with the proviso that when R 1  is hydrogen, m is 0, and n is more than or equal to 1; 
 R 2  is a hydrocarbyl group, typically containing 1 to 150 carbon atoms; 
 R 3 , R 4  and R 5  are independently hydrocarbyl groups or hydroxy-containing hydrocarbyl groups or carboxyl-containing hydrocarbyl groups; and 
 R 6  is hydrogen or a hydrocarbyl group, typically containing 1 to 150 carbon atoms. 
 
   
   
       2 . The lubricating composition of  claim 1 , wherein the ashless antiwear agent of Formula (1) is derived from at least one hydroxy-polycarboxylic acid. 
   
   
       3 . The lubricating composition of  claim 1  wherein the ashless anti-wear agent comprises a hydroxy-polycarboxylic acid di-ester, a hydroxy-polycarboxylic acid di-amide, a hydroxyl-polycarboxylic acid imide, a hydroxy-polycarboxylic acid di-imide, a hydroxy-polycarboxylic acid ester-amide, a hydroxy-polycarboxylic acid ester-imide, and a hydroxy-polycarboxylic acid imide-amide. 
   
   
       4 . The lubricating composition of  claim 1 , wherein the ashless antiwear agent represented by Formula (1) is an imide, a di-ester, or a di-amide. 
   
   
       5 . The lubricating composition of  claim 1 , wherein Y and Y′ of Formula (1) are both —O—. 
   
   
       6 . The lubricating composition of  claim 1 , wherein Formula (1) defines m as 0 or 1, n as 1 to 2, X is >CHOR 6 , and R 1 , R 2  and R 6  are independently hydrogen or hydrocarbyl groups containing 4 to 30 carbon atoms. 
   
   
       7 . The lubricating composition of  claim 1  wherein the ashless antiwear agent is derived from tartaric acid or citric acid. 
   
   
       8 . The lubricating composition of  claim 1 , wherein the ashless antiwear agent is present at 0.05 to 10 wt %, or 0.1 to 5 wt % of the lubricating composition. 
   
   
       9 . The lubricating composition of  claim 1 , wherein the oil-soluble molybdenum compound is selected from at least one member of the group consisting of molybdenum dithiocarbamates, molybdenum dialkyldithiophosphates, amine salts of molybdenum compounds, molybdenum xanthates, molybdenum sulphides, molybdenum carboxylates, and molybdenum alkoxides. 
   
   
       10 . The lubricating composition of  claim 9 , wherein the oil-soluble molybdenum compound is selected from at least one member of the group consisting of molybdenum dithiocarbamates, molybdenum dialkyldithiophosphates, and amine salts of molybdenum compounds. 
   
   
       11 . The lubricating composition of  claim 10 , wherein the oil-soluble molybdenum compound is a molybdenum dithiocarbamate. 
   
   
       12 . The lubricating composition of  claim 1 , wherein the oil-soluble molybdenum compound is present in an amount to provide 0.5 ppm to 2000 ppm, 1 ppm to 700 ppm, or 20 ppm to 250 ppm of molybdenum. 
   
   
       13 . The lubricating composition of  claim 1 , wherein the lubricating composition is further characterised as having at least one of (i) a sulphur content of 0.8 wt % or less, (ii) a phosphorus content of 0.2 wt % or less, or (iii) a sulphated ash content of 2 wt % or less. 
   
   
       14 . The lubricating composition of  claim 1 , wherein the lubricating composition is characterised as having (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. 
   
   
       15 . The lubricating composition of  claim 1  further comprises at least one of a friction modifier (other than an oil-soluble molybdenum compound or a compound of Formula (1)), a viscosity modifier, an antioxidant (other than the oil-soluble molybdenum compound), an overbased detergent, a succinimide dispersant, or mixtures thereof. 
   
   
       16 . The lubricating composition of  claim 15 , wherein the friction modifier is selected from the group consisting of long chain fatty amides, long chain fatty esters, long chain fatty epoxide derivatives, long chain fatty imidazolines, and amine salts of alkylphosphoric acids. 
   
   
       17 . The lubricating composition of  claim 1  further comprising a phosphorus-containing antiwear agent. 
   
   
       18 . The lubricating composition of  claim 1  further comprising an overbased detergent. 
   
   
       19 . The lubricating composition of  claim 18 , wherein the overbased detergent is selected from the group consisting of non-sulphur-containing phenates, sulphur-containing phenates, sulphonates, salixarates, salicylates, and mixtures thereof. 
   
   
       20 . A method of lubricating an internal combustion engine comprising, supplying to the internal combustion engine the lubricating composition of  claim 1 . 
   
   
       21 - 22 . (canceled)