Lubricant composition comprising branched diesters and viscosity index improver

Abstract

The invention refers to lubricant compositions comprising a specific diester together with a viscosity index improver.

1 . Lubricant composition comprising at least one compound of formula (I) below and at least one viscosity index improver 
       
         
           
           
               
               
           
         
         wherein: 
         n is below 1.1 
         R1 represents a linear or branched, saturated or unsaturated C3-C20, 
         R′ represents a linear or branched, saturated or unsaturated C2-C16, 
         R represents a linear or branched, saturated or unsaturated C1-C20. 
       
     
     
         2 . Lubricant composition of  claim 1 , wherein in the formula (I): n is 1;
 the total amount of carbon atoms being more than 15 and less than 40.   
     
     
         3 . Lubricant composition of  claim 1 , wherein in the formula (I):
 R1 represents a linear or branched, saturated or unsaturated C5-C15 a Iky I group;   R′ represents a linear or branched, saturated or unsaturated C3-C8 a Iky I group; R represents a linear or branched, saturated or unsaturated C1-C15 alkyl group.   
     
     
         4 . Lubricant composition according to  claim 1 , wherein in the compound of formula (I),
 R1 represents a saturated linear C5-C15 alkyl group, more preferably a saturated linear C5-C12 alkyl group; R′ represents a saturated linear C3-C8 alkyl group, more preferably a saturated linear C5-C8 alkyl group;   R represents a saturated linear or branched C5-C15 alkyl group, more preferably a saturated linear or branched C5-C10 alkyl group.   
     
     
         5 . Lubricant composition according to  claim 1 , wherein in the formula (I):
 R1 represents a saturated linear C5-C10 alkyl group, more preferably a saturated linear C5-C8 alkyl group;   R′ represents a saturated linear C5-C8 alkyl group;   R represents a saturated, linear or branched C5-C10 alkyl group, preferably a saturated linear C5-C10 alkyl group.   
     
     
         6 . Lubricant composition according to  claim 5 , wherein the compound of formula (I) is a compound of formula (Ia) 
       
         
           
           
               
               
           
         
       
     
     
         7 . Lubricant composition according to  claim 1 , wherein in the formula (I):
 R1 represents a saturated linear or branched C5-C 5 alkyl group, more preferably a saturated linear C8-C12 alkyl group;   R′ represents a saturated linear C5-C8 alkyl group;   R represents a saturated, linear or branched C5-C10 alkyi group, preferably a saturated branched C5-C10 alkyl group.   
     
     
         8 . Lubricant composition according to  claim 7 , wherein the compound of formula (I) is a compound of formula (Ib) 
       
         
           
           
               
               
           
         
       
     
     
         9 . Lubricant composition according to  claim 1 , wherein the viscosity index improver is a polymeric viscosity index improver, preferably chosen among: polyacrylates and polymethacrylates,
 olefin homopolymers or copolymers, preferably ethylene/propylene   styrene copolymers, preferably with isoprene or a diene such as butadiene, hydrogen ated or not, isoprene polymers, preferably radial hydrogenated polyisoprene,   esterified polystyrenes, preferably esterified poiy(styrene-co-maleic anhydride) mixtures of two or more of the above.   
     
     
         10 . Lubricant composition according to claim L comprising from 0, 1 to 50%, preferably from 1 to 50%, more preferably from 5 to 30% by weight based on the total weight of lubricant composition, of a compound of formula (I). 
     
     
         11 . Lubricant composition according to  claim 1 , comprising from 0.01 to 15%, preferably from 1 to 10% by weight based on the total weight of lubricant composition, of at least one viscosity index improver. 
     
     
         12 . Lubricant composition according to  claim 1 , further comprising at least one lubricant base oil. 
     
     
         13 . Lubricant composition according to  claim 1 , wherein the lubricant base oil is a group III lubricant base oil. 
     
     
         14 . Lubricant composition according to  claim 1 , comprising from 50 to 99%, preferably from 50 to 80% by weight based on the total weight of lubricant composition, of a lubricant base oil. 
     
     
         15 . Lubricant composition according to  claim 1 , further comprising at least one lubricant additive selected from the list consisting of detergent additives, anti-wear additives, friction modifiers additives, extreme pressure additives, antioxidant additives, dispersing agents, pour-point depressant additives, anti-foam agents, thickeners and mixtures of two or more thereof. 
     
     
         16 . Use of a lubricant composition according to  claim 1 , to reduce the fuel consumption of an engine, preferably of a car engine and/or to improve the cleanliness of an engine, preferably of a car engine, more preferably of at least one piston of a car engine.