Lubricating Composition Containing an Antiwear Agent

Abstract

The invention provides a lubricating composition containing (a) an oil of lubricating viscosity, (b) a phosphite having at least one hydrocarbyl group that has 4 or more carbon atoms, and (c) a compound derived from a hydroxy-carboxylic acid. The invention further relates to the use of the lubricating composition in an internal combustion engine.

1 . A lubricating composition comprising
 (a) an oil of lubricating viscosity,   (b) 0.01 wt % to 5 wt % of a phosphite having at least one hydrocarbyl group that has 4 or more carbon atoms, wherein the phosphite having at least one hydrocarbyl group with 4 or more is represented by the formula:   
       
         
           
           
               
               
           
         
       
       wherein at least one of R 3 , R 4  and R 5  is a hydrocarbyl group containing at least 4 carbon atoms and the other may be hydrogen or a hydrocarbyl group, and wherein the phosphite has at least one hydrocarbyl group with 12 to 22 carbon atoms, and
 (c) 0.01 wt % to 5 wt % of a compound derived from a hydroxy-carboxylic acid, wherein the compound derived from a hydroxy-carboxylic acid is represented by the formula: 
 
       
         
           
           
               
               
           
         
       
       wherein 
       n and m are independently integers of 1 to 5; 
       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—, >NH, or >NR 1  or two Ys together representing the nitrogen of an imide structure R—N< formed between two carbonyl groups; and
 each R and R 1  is 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 wherein n=2 and m=1, or n and m both equal 2, or n=3 and n=1, or n=2 and m=0. 
 
     
     
         2 . The lubricating composition of  claim 1 , wherein n and m both equal 2. 
     
     
         3 - 18 . (canceled) 
     
     
         19 . The lubricating composition of  claim 1 , wherein the compound derived from the hydroxy-carboxylic acid is present at 0.1 wt % to 3 wt % of the lubricating composition. 
     
     
         20 . The lubricating composition of  claim 1 , wherein the compound derived from the hydroxy-carboxylic acid is present at 0.5 wt % to 1 wt % of the lubricating composition 
     
     
         21 . The lubricating composition of  claim 1 , wherein both R 3  and R 4  are hydrocarbyl groups. 
     
     
         22 . The lubricating composition of  claim 1 , wherein the phosphite has at least one hydrocarbyl group with 14 to 20 carbon atoms. 
     
     
         23 . The lubricating composition of  claim 1 , wherein the phosphite has at least one hydrocarbyl group with 16 to 18 carbon atoms. 
     
     
         24 . The lubricating composition of  claim 1 , wherein the phosphite having at least one hydrocarbyl group with 4 or more carbon atoms is present at 0.1 wt % to 3 wt %, of the lubricating composition. 
     
     
         25 . The lubricating composition of  claim 1 , wherein the phosphite having at least one hydrocarbyl group with 4 or more carbon atoms is present at 0.5 wt % to 1 wt % of the lubricating composition. 
     
     
         26 . The lubricating composition of  claim 1 , wherein the phosphite having at least one hydrocarbyl group with 4 or more carbon atoms and the compound derived from the hydroxy-carboxylic acid are both present in an amount in the range of 0.1 wt % to 3 wt % and 0.1 wt % to 3 wt % respectively of the lubricating composition. 
     
     
         27 . The lubricating composition of  claim 1 , wherein the phosphite having at least one hydrocarbyl group with 4 or more carbon atoms and the compound derived from the hydroxy-carboxylic acid are both present in an amount in the range of 0.5 wt % to 1 wt % and 0.5 wt % to 1 wt % respectively of the lubricating composition. 
     
     
         28 . The lubricating composition of  claim 1  further comprising a zinc dialkyldithiophosphate, or mixtures thereof, wherein the zinc dialkyldithiophosphate is present at 0.75 wt % to 1.5 wt % of the lubricating composition. 
     
     
         29 . 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. 
     
     
         30 . The lubricating composition of  claim 1  further comprising at least one of an antiwear agent, a dispersant viscosity modifier, a friction modifier, a viscosity modifier, an antioxidant, an overbased detergent, or mixtures thereof. 
     
     
         31 . The lubricating composition of  claim 1  further comprising an overbased detergent, wherein the overbased detergent is selected from the group consisting of phenates, sulphur containing phenates, sulphonates, salixarates, salicylates, and mixtures thereof. 
     
     
         32 . A method of lubricating an internal combustion engine comprising supplying to the internal combustion engine the lubricating composition of  claim 1 . 
     
     
         33 . The method of  claim 32 , wherein the internal combustion engine has surfaces of an aluminium alloy, or aluminium composite. 
     
     
         34 . The method of  claim 33 , wherein the aluminium alloy is a eutectic or hyper-eutectic aluminium alloy. 
     
     
         35 . The method of  claim 34 , wherein the aluminium alloy is derived from an aluminium silicate. 
     
     
         36 . The method of  claim 32 , wherein the internal combustion engine has surfaces of steel.