Lubricant composition for industrial engines with increased fe potential

Abstract

The present invention relates to the field of multipurpose lubricants which may be used in the various components of automotive vehicles, notably in the engine, the transmission or the hydraulic circuit.The invention relates to the use of at least one polymer which improves the viscosity index, chosen from hydrogenated copolymers of diene and of aromatic vinyl, in a lubricant composition for decreasing the viscosity of said lubricant composition in the course of the use of said lubricant composition during the lubrication of the various components of an industrial vehicle, notably of a diesel engine industrial vehicle, such as the engine, the gearbox and the hydraulic circuit, said lubricant composition undergoing at least one thermal shear during its use.

1 - 15 . (canceled) 
     
     
         16 . A method for preparing a lubricant composition for an industrial vehicle, the method comprising:
 forming a lubricant composition by adding a copolymer to a base oil, in an amount sufficient to reduce the viscosity of the lubricant composition when the lubricant composition is thermally sheared while lubricating components of an industrial vehicle,   wherein the copolymer comprises hydrogenated diene monomers and hydrogenated aromatic vinyl monomers.   
     
     
         17 . The method of  claim 16 , wherein the diene monomer is chosen from conjugated diene monomers comprising from 4 to 20 carbon atoms. 
     
     
         18 . The method of  claim 16 , wherein the aromatic vinyl monomer comprises from 8 to 16 carbon atoms. 
     
     
         19 . The method of  claim 16 , wherein the copolymer is a block copolymer or a star copolymer. 
     
     
         20 . The method of  claim 16 , wherein the copolymer is chosen from a hydrogenated copolymer of isoprene and styrene (HCIS), a hydrogenated copolymer of isoprene, butadiene and styrene, a hydrogenated copolymer of butadiene and styrene (HCBS), and a mixture thereof. 
     
     
         21 . The method of  claim 16 , wherein the lubricant composition comprises from 0.1% to 10% by weight of the copolymer, relative to the total weight of the lubricant composition. 
     
     
         22 . The method of  claim 16 , wherein the lubricant composition further comprises one or more additives chosen from friction-modifying additives, anti-wear additives, extreme-pressure additives, detergent additives, antioxidant additives, viscosity index (VI) enhancers other than the hydrogenated copolymers of diene and of aromatic vinyl, pour-point depressant (PPD) additives, dispersants, antifoams, thickeners, or mixtures thereof. 
     
     
         23 . The method of  claim 16 , wherein the lubricant composition has a kinematic viscosity at 100° C. of between 9.3 and 16.3 cSt, as measured by the ASTM D445 standard, after being thermally sheared. 
     
     
         24 . The method of  claim 16 , wherein the viscosity reduction is sufficient to improve the fuel economy of the industrial vehicle. 
     
     
         25 . The method of  claim 16 , wherein the lubricant composition is configured to undergo mechanical shearing while lubricating the components of the industrial vehicle. 
     
     
         26 . The method of  claim 16 , wherein the copolymer is a hydrogenated copolymer of isoprene and styrene. 
     
     
         27 . The method of  claim 26 , wherein the hydrogenated copolymer of isoprene and styrene has formula (I) or (II) below: 
       
         
           
           
               
               
           
         
         wherein,
 R1, R2, R3 and R4 are respectively hydrogenated isoprene/styrene/isoprene copolymers, and 
 l, m, n and o are, independently integers greater than or equal to 0, such that the number-average molar mass of the hydrogenated copolymer of isoprene and styrene ranges from 10,000 to 700,000. 
 
       
     
     
         28 . The method of  claim 16 , wherein the copolymer is a hydrogenated copolymer of butadiene and styrene. 
     
     
         29 . The method of  claim 28 , wherein the hydrogenated copolymer of butadiene and styrene has formula (I′) or (II′) below: 
       
         
           
           
               
               
           
         
         wherein,
 R 1 ′, R2′, R3′ and R4′ are respectively hydrogenated butadiene/styrene/butadiene copolymers, and 
 l, m, n, and o are independently integers greater than or equal to 0, such that the number-average molar mass of the hydrogenated copolymer of butadiene and styrene ranges from 10,000 to 700,000. 
 
       
     
     
         30 . A method for lubricating components of an industrial vehicle, the method comprising:
 lubricating the components of the industrial vehicle with a lubricant composition during operation of the industrial vehicle, such that the lubricant composition is thermally sheared and the viscosity index of the lubricant composition is reduced over time,   wherein the lubricant composition comprises a base oil and a copolymer comprising hydrogenated diene monomers and hydrogenated aromatic vinyl monomers.   
     
     
         31 . The method of  claim 30 , wherein the components of the industrial vehicle comprise a diesel engine, a gearbox, and a hydraulic circuit. 
     
     
         32 . The method of  claim 16 , wherein the diene monomer is chosen from a conjugated diene monomers comprising from 2 to 12 carbon atoms. 
     
     
         33 . The method of  claim 16 , wherein the lubricant composition comprises from 0.1% to 2% by weight of the copolymer, relative to the total weight of the lubricant composition. 
     
     
         34 . The method of  claim 16 , wherein the lubricating comprises lubricating an engine, a gearbox and a hydraulic circuit of the industrial vehicle. 
     
     
         35 . The method of  claim 34 , wherein the lubricating comprises thermally and mechanically shearing the lubricant composition, without supplying external oxygen to the lubricant composition.