Ether-Based Lubricant Compositions, Methods and Uses

Abstract

The present invention provides a lubricant composition for an internal combustion engine comprising a base oil of lubricating viscosity, wherein the base oil comprises an ether base stock of formula (A): where: Ra and Rb are aliphatic hydrocarbyl groups and may be the same or different; wherein at least one of Ra and Rb is branched-chain alkyl, alkoxy-substituted-alkyl or cycloalkyl-substituted-alkyl; the lubricant composition further comprising: i) at least one molybdenum compound as a lubricant additive which is present, on a molybdenum element basis, in an amount of at least 0.06% by weight of the lubricant composition; or ii) at least one polymethacrylate compound as a lubricant additive which is present in an amount of from 0.1 to 7.5% by weight of the lubricant composition. The lubricant composition may be used for lubricating a surface in an internal combustion engine as well as for improving the fuel economy performance and/or piston cleanliness performance and/or turbocharger cleanliness performance of an engine and/or a vehicle, such as an automotive vehicle associated with an internal combustion engine.

1 . A lubricant composition for an internal combustion engine comprising a base oil of lubricating viscosity, wherein the base oil comprises an ether base stock of formula (A): 
       
         
           
           
               
               
           
         
       
       where: R a  and R b  are aliphatic hydrocarbyl groups and may be the same or different; wherein at least one of R a  and R b  is branched-chain alkyl, alkoxy-substituted-alkyl or cycloalkyl-substituted-alkyl;
 the lubricant composition further comprising: 
 i) at least one molybdenum compound as a lubricant additive which is present, on a molybdenum element basis, in an amount of at least 0.06% by weight of the lubricant composition; or 
 ii) at least one polymethacrylate compound as a lubricant additive which is present in an amount of from 0.1 to 7.5% by weight of the lubricant composition. 
 
     
     
         2 . The lubricant composition of  claim 1 , wherein R a  and R b  are independently selected from alkyl, alkoxy-substituted-alkyl or cycloalkyl-substituted-alkyl, provided that when R a  and R b  are both alkyl at least one of R a  and R b  is/are branched-chain alkyl. 
     
     
         3 . The lubricant composition of  claim 1 , wherein R a  contains more carbon atoms than R b . 
     
     
         4 . The lubricant composition of  claim 1 , wherein R a  contains from 12 to 30 carbon atoms, and/or R b  contains from 2 to 20 carbon atoms. 
     
     
         5 . The lubricant composition of  claim 1 , wherein the ether base stock is of formula (1): 
       
         
           
           
               
               
           
         
       
       where: R 1  and R 2  are alkyl or, together with the carbon atom to which they are attached, cycloalkyl;
 R 3 , R 4  and R 5  are H or alkyl; 
 R 6  is alkyl or 
 
       
         
           
           
               
               
           
         
       
       where: R 7  and R 8  are H, alkyl or, together with the carbon atom to which they are attached, cycloalkyl;
 R 9  is H or alkyl; 
 X is alkylene or is absent; and 
 p is 0, 1, 2 or 3; and 
 m and n are 0, 1, 2 or 3, wherein m is 0 when R 4  and R 5  are H. 
 
     
     
         6 . The lubricant composition of  claim 5 , wherein R 1  and R 2  are C 1-15  alkyl or, together with the carbon atom to which they are attached, C 5-30  cycloalkyl; and/or wherein R 3 , R 4  and R 5  are H or C 1-15  alkyl. 
     
     
         7 . The lubricant composition of  claim 5 , wherein m and n are 0, 1 or 2. 
     
     
         8 . The lubricant composition of  claim 5 , wherein the ether base stock has the formula (4): 
       
         
           
           
               
               
           
         
       
       where: R 1  and R 4  are alkyl;
 R 3  and R 5  are H or alkyl. 
 
     
     
         9 . The lubricant composition of  claim 5 , wherein the ether base stock has the formula (7): 
       
         
           
           
               
               
           
         
       
       where: R 1  and R 2  are alkyl or, together with the carbon to which they are attached, cycloalkyl;
 R 3 , R 4  and R 5  are H or alkyl; and 
 R 6  is alkyl. 
 
     
     
         10 . The lubricant composition of  claim 1 , wherein the ether base stock contains a total number of carbons atoms of from 20 to 50. 
     
     
         11 . The lubricant composition of  claim 1 , wherein the ether base stock is prepared from bio-derived feedstock containing greater than 50% by weight of biobased carbon. 
     
     
         12 . The lubricant composition of  claim 1 , wherein the at least one molybdenum compound is present, on a molybdenum element basis, in an amount from 0.06% to 0.25% by weight of the lubricant composition. 
     
     
         13 . The lubricant composition of  claim 1 , wherein the at least one polymethacrylate compound is present in an amount of from 0.25 to 7% by weight of the lubricant composition. 
     
     
         14 . The lubricant composition of  claim 1 , wherein the at least one polymethacrylate compound is a comb-type polymer. 
     
     
         15 . The lubricant composition of  claim 1 , wherein the base oil of the lubricant composition comprises greater than 10% by weight of the ether base stock and/or wherein the lubricant composition comprises greater than 50% by weight of the base oil. 
     
     
         16 . The lubricant composition of  claim 15 , wherein the base oil of the lubricant composition further comprises a base stock selected from Group I, Group II, Group III, Group IV and Group V base stocks and mixtures thereof. 
     
     
         17 . The lubricant composition of  claim 1 , wherein the lubricant composition has at least one of:
 a kinematic viscosity at 40° C. of less than 60 cSt;   a kinematic viscosity at 100° C. of less than 12 cSt;   a viscosity index of greater than 100;   a viscosity at 150° C. and a shear rate of 10 6  s −1  of no greater than 3 cP; and   a Noack volatility of less than 25% by weight.   
     
     
         18 . The lubricant composition of  claim 1 , wherein the lubricant composition has at least one of:
 an oxidative stability performance on a CEC-L-088-02 test indicated by an absolute viscosity increase at 40° C. of no more than 45 cSt;   an oxidative stability performance on a CEC-L-109-14 test indicated by an increase in kinematic viscosity at 100° C. of less than 200%;   a fuel economy performance on a CEC-L-054-96 test of at least 2.5%;   a piston cleanliness performance on a CEC-L-088-02 test indicated by an overall piston merit of at least 8.5; and   a high temperature stability performance on a KHT test at 280° C. in accordance with JPI-5S-55-99 indicated by an overall deposit merit of at least 7.0.   
     
     
         19 . The lubricant composition of  claim 1 , wherein the composition further comprises a phenate detergent in an amount of 0.1 to 5% by weight actives of the lubricant composition. 
     
     
         20 . The lubricant composition of  claim 1 , wherein the composition further comprises a neutral sulphonate detergent in an amount of 0.01 to 5% by weight of the lubricant composition. 
     
     
         21 . A method of preparing a lubricant composition, said method comprising providing a base oil as defined in  claim 1  and blending the base oil with: i) at least one molybdenum compound suitable for use as a lubricant additive such that the molybdenum compound is present, on a molybdenum element basis, in an amount of at least 0.06% by weight of the lubricant composition; or ii) at least one polymethacrylate compound suitable for use as a lubricant additive such that the polymethacrylate compound is present in an amount of from 0.1 to 7.5% by weight of the lubricant composition, and optionally also blending one or more additional lubricant additives, in order to prepare the lubricant composition. 
     
     
         22 . A method of lubricating a surface, said method comprising supplying a lubricant composition as defined in  claim 1  to said surface, such as wherein the lubricant composition is supplied to a surface in an internal combustion engine. 
     
     
         23 - 26 . (canceled) 
     
     
         27 . A method of reducing or preventing i) scuffing in the piston system of an engine and/or ii) deposits in the turbochargers of an engine, comprising the step of providing to the engine a lubricant composition according to  claim 1 . 
     
     
         28 . A method of improving the fuel economy performance and/or piston cleanliness performance and/or turbocharger cleanliness performance of an engine and/or a vehicle, comprising the step of providing to the engine a lubricant composition according to  claim 1 .