The use of polyalkylene glycol esters in lubricating oil compositions

Abstract

The presently claimed invention is directed to the use of polyalkylene glycol ester that are prepared by reacting polytetrahydrofuran with at least one C 9 -C 27 acid in lubricating oil compositions.

1 .- 15 . (canceled) 
     
     
         16 . A lubricant which comprises a polyalkylene glycol ester of the formula (I) 
       
         
           
           
               
               
           
         
         wherein 
         k is an integer in the range of ≧2 to ≦30, and 
         R 1  and R 2 , identical or different, each denote an unsubstituted, branched alkyl radical having 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25 or 26 carbon atoms. 
       
     
     
         17 . The lubricant according to  claim 16 , wherein k is an integer in the range of ≧3 to ≦25. 
     
     
         18 . The lubricant according to  claim 16 , wherein the polyalkylene glycol ester of the formula (I) has a weight average molecular weight Mw in the range of ≧500 to ≦4500 g/mol, determined according to DIN 55672-1 (polystyrene calibration standard). 
     
     
         19 . The lubricant according to  claim 16 , wherein the polyalkylene glycol ester of the formula (I) has a number average molecular weight Mn in the range of ≧400 to ≦4000 g/mol, determined according to DIN 55672-1 (polystyrene calibration standard). 
     
     
         20 . The lubricant according to  claim 16 , wherein the polyalkylene glycol ester of the formula (I) has a polydispersity in the range of ≧1.1 to ≦2.0, determined according to DIN 55672-1 (polystyrene calibration standard). 
     
     
         21 . The lubricant according to  claim 16 , wherein R 1  and R 2 , identical or different, each denote a moiety selected from the group consisting of 
       
         
           
           
               
               
           
         
         whereby n is an integer in the range of ≧8 to ≦23, 
       
       
         
           
           
               
               
           
         
         whereby m is an integer in the range of ≧7 to ≦22, 
       
       
         
           
           
               
               
           
         
         whereby o is an integer in the range of ≧1 to ≦6, p is an integer in the range of ≧2 to ≦19, and (o+p) is an integer in the range of ≧8 to ≦21, 
         and 
       
       
         
           
           
               
               
           
         
         whereby Q is an integer in the range of ≧1 to ≦6, R is an integer in the range of ≧2 to ≦19, and (Q+R) is an integer in the range of ≧8 to ≦20. 
       
     
     
         22 . The lubricant according to  claim 16 , wherein R 1  and R 2  are identical. 
     
     
         23 . The lubricant according to  claim 16 , wherein the polyalkylene glycol ester of the formula (I) has a total acid number in the range of ≧0.01 to ≦2.5 mg KOH/g, determined according to ASTM D664. 
     
     
         24 . The lubricant according to  claim 16 , wherein the polyalkylene glycol ester of the formula (I) has a hydroxyl number in the range of ≧0.1 to ≦20 mg KOH/g, determined according to DIN 53240. 
     
     
         25 . The lubricant according to  claim 16 , wherein
 k is an integer in the range of ≧3 to ≦25,   and   R 1  and R 2 , identical, each denote a moiety selected from the group consisting of   
       
         
           
           
               
               
           
         
         whereby n is 10, 11, 12, 13, 14, 15, 16, 17 or 18. 
       
     
     
         26 . A lubricating oil composition comprising at least one polyalkylene glycol ester of the the formula (I) as defined in  claim 16 . 
     
     
         27 . A method for reducing the friction coefficient of a lubricating oil composition in the lubrication of a mechanical device comprising formulating said lubricating oil composition with at least one polyalkylene glycol ester of the formula (I) 
       
         
           
           
               
               
           
         
         wherein 
         k is an integer in the range of ≧2 to ≦30, and 
         R 1  and R 2 , identical or different, each denote an unsubstituted, branched alkyl radical having 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25 or 26 carbon atoms. 
       
     
     
         28 . The method according to  claim 27 , wherein the friction coefficient is measured at 0-25% slide roll ratio (SRR), mean speed 4 m m/s, using mini-traction machine (MTM) measurements at 70° C. and 1 GPa loading. 
     
     
         29 . A method of enhancing the friction modification properties of a lubricating oil composition in the lubrication of a mechanical device comprising formulating said lubricating oil composition with at least one polyalkylene glycol ester of formula (I) 
       
         
           
           
               
               
           
         
         wherein 
         k is an integer in the range of ≧2 to ≦30, and 
         R 1  and R 2 , identical or different, each denote an unsubstituted, branched alkyl radical having 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25 or 26 carbon atoms.