Lubricating composition substantially free of ZDDP

Abstract

The present invention provides a composition comprising: (a) a metal salixarate; (b) at least one additive selected from the group consisting of (1) an antioxidant; (2) a friction modifier; (3) a dispersant; (4) a viscosity modifier; (5) a dispersant viscosity modifier; and (6) an antiwear agent other than a metal hydrocarbyl dithiophosphate; and (c) an oil of lubricating viscosity, wherein the composition contains 400 ppm or less of phosphorus derived from a metal hydrocarbyl dithiophosphate. The invention further provides a process for preparing the composition and its use.

1 . A composition comprising: 
 (a) a metal salixarate;    (b) at least one additive selected from the group consisting of (1) an antioxidant; (2) a friction modifier; (3) a dispersant; (4) a viscosity modifier; (5) a dispersant viscosity modifier; and (6) an antiwear agent other than a metal hydrocarbyl dithiophosphate; and    (c) an oil of lubricating viscosity, wherein the composition contains about 400 ppm or less of phosphorus derived from a metal hydrocarbyl dithiophosphate.    
     
     
         2 . The composition of  claim 1 , wherein the metal salixarate is represented by one or a mixture of substantially linear compounds comprising at least one unit of the formulae (I) or (II):  
       
         
           
           
               
               
           
         
       
       each end of the compound having a terminal group of formulae (III) or (IV):  
       
         
           
           
               
               
           
         
       
       such groups being linked by divalent bridging groups, which may be the same or different for each linkage; wherein in formulas (I)-(IV) f is 1, 2 or 3, preferably 1 or 2; U is —OH, —NH 2  —NHR 1 , —N(R 1 ) 2  or mixtures thereof, R 1  is a hydrocarbyl group containing 1 to 5 carbon atoms; R 2  is hydroxyl or a hydrocarbyl group and j is 0, 1, or 2; R 3  is hydrogen or a hydrocarbyl group; R 4  is a hydrocarbyl group or a substituted hydrocarbyl group; g is 1, 2 or 3, provided at least one R 4  group contains 8 or more carbon atoms; and wherein the molecules on average contain at least one of unit (I) or (III) and at least one of unit (II) or (IV) and the ratio of the total number of units (I) and (III) to the total number of units of (II) and (IV) in the composition overall is about 0.1:1 to about 2:1, although individual molecules within the composition may fall outside this range.  
     
     
         3 . The composition of  claim 1 , wherein the metal of the metal salixarate is an alkali metal or alkaline earth metal.  
     
     
         4 . The composition of  claim 1 , wherein the total sulphur content is below about 0.5 weight percent and the total phosphorus content is below about 0.07 weight percent.  
     
     
         5 . The composition of  claim 1 , wherein the total sulphated ash content is below about 1.5 weight percent.  
     
     
         6 . The composition of  claim 1 , wherein the dispersant is a N-substituted long chain alkenyl succinimide.  
     
     
         7 . The composition of  claim 1 , wherein the antioxidant is a diphenylamine, a hindered phenol or mixtures thereof.  
     
     
         8 . The composition of  claim 7  wherein the diphenylamine is represented by the formula:  
       
         
           
           
               
               
           
         
       
       wherein each R 6  and R 7  are independently a hydrocarbyl group; and z is zero or higher, provided that on at least one ring, z is non-zero.  
     
     
         9 . The composition of  claim 7  wherein the hindered phenol is represented by the formulae:  
       
         
           
           
               
               
           
         
       
       wherein R 8  and R 9  are independently branched or linear alkyl groups containing 1 to 24 carbon atoms; Y is a bridging group; and E is hydrogen, a hydrocarbyl group, a bridging group linking to a second aromatic group, an ester-containing group, or mixtures thereof.  
     
     
         10 . The composition of  claim 1 , wherein the friction modifier comprises a monoester of a polyol and an aliphatic carboxylic acid.  
     
     
         11 . The composition of  claim 1 , wherein the viscosity modifier comprises an olefin copolymer.  
     
     
         12 . The composition of  claim 11 , wherein the olefin copolymer contains an ethylene monomer and at least one other comonomer derived from an alpha-olefin having the formula H 2 C═CHR 10 , wherein R 10  is a hydrocarbyl group.  
     
     
         13 . The composition of  claim 1 , wherein the dispersant viscosity modifier is selected from the group consisting of (a) an olefin copolymer grafted with an unsaturated dicarboxylic acid anhydride or derivatives thereof and an amine; (b) a polymethacrylate functionalised with an amine; (c) an esterified copolymer comprising (i) styrene, (ii) an unsaturated dicarboxylic acid anhydride or derivatives thereof, optionally functionalised with an amine; and mixtures thereof.  
     
     
         14 . The composition of  claim 1 , wherein the oil of lubricating viscosity is selected from the group consisting of API Group II, III, IV or V oil and mixtures thereof.  
     
     
         15 . The composition of  claim 1 , wherein the metal salixarate is present on an oil free basis at about 0.01 to about 20 weight percent of the composition; wherein the additives (1)-(6) of component (b) are each present on an oil free basis at 0 to 25 weight percent of the composition, with the proviso that at least one additive is present at 0.1 or more weight percent of the composition; and wherein the oil of lubricating viscosity is present at up to 99.89 weight percent of the composition.  
     
     
         16 . A process for the preparation of a composition comprising mixing: 
 (a) a metal salixarate;    (b) at least one additive selected from the group consisting of (1) an antioxidant; (2) a friction modifier; (3) a dispersant; (4) a viscosity modifier; (5) a dispersant viscosity modifier; and (6) an antiwear agent other than a metal hydrocarbyl dithiophosphate; and    (c) an oil of lubricating viscosity, wherein the composition contains about 400 ppm or less of phosphorus derived from a metal hydrocarbyl dithiophosphate.    
     
     
         17 . A product prepared by the process of  claim 16 .  
     
     
         18 . A method for lubricating an internal combustion engine, comprising supplying thereto a lubricant comprising the composition  claim 1 .  
     
     
         19 . The use of the composition of  claim 1  for imparting one or more of the group selected from improved engine cleanliness, decreased wear, decreased NO, emissions and decreased particulate emissions.