Multifunctional lubricating fluid

Abstract

The application pertains to multifunctional lubricating fluids for use in the different assemblies of automotive vehicles, mainly the engine, the transmission or a hydraulic circuit, and relates to a lubricant composition containing at least one oil of the groups I to V and a mixture of at least two polymers having a difference of the permanent shearing stability index (PSSI), as measured by the standardised KRL test for 20 hours at 1000° C., of at least 50, and having a viscosity profile such that: (a) at 1000° C., after a 30 cycle Bosch test following the CEC-L-14-A-93 standard, the viscosity of the final lubricant composition is higher than 9.0 cSt, preferably in range of 9.0 to 12.0 cSt for a 30 grade starting oil, or the viscosity of the final lubricant composition is higher than 12.0 cSt, preferably in range of 12.0 to 15.0 cSt for a 40 grade starting oil; (b) at 1000° C., after a 20 hour KRL test following the CEC-L-45-A-99 standard, the viscosity of the final lubricant composition is higher than 8.5 cSt, preferably in range of 8.5 to 11.0 cSt for a 30 or 40 grade starting oil; and (c) at 400° C., after a 3 hour KRL test following the CEC-L-45-A-99 standard with a test duration down to 3 hours, the viscosity of the final lubricant composition is lower than 51.0 cSt, preferably in range of 41 to 51 cSt for a 30 or 40 grade starting oil.

1 . A lubricating composition comprising at least one oil of groups I to V and a mixture of at least two polymers having a difference of permanent shear stability index (PSSI), measured after the standardized KRL 20 hours test at 100° C. of at least 25, and having a viscosity profile comprising:
 (a) at 100° C. after the Bosch-30 cycles test according to the CEC-L-14-A-93 standard the viscosity of the final lubricating composition is greater than 9.0 cSt, preferably in the range from 9.0 to 12.0 cSt for an oil initially of grade 30, or else the viscosity of the final lubricating composition is greater than 12.0 cSt, preferably in the range from 12.0 to 15.0 cSt for an oil initially of grade 40, and   (b) at 100° C. after the KRL-20 hours test according to the CEC-L-45-A-99 standard the viscosity of the lubricating composition is in the range from 8.5 to 11.0 cSt for an oil initially of grade 30 or 40, and   (c) at 40° C. after the KRL-3 hours test, according to the CEC-L-45-A-99 standard with the test duration reduced to 3 hours, the viscosity of the lubricating composition is less than 51 cSt, preferably in the range from 41 to 51 cSt for an oil initially of grade 30 or 40.   
   
   
       2 . A lubricating composition comprising at least one base oil of groups I to V, and a mixture of at least two polymers having a difference of permanent shear stability index (PSSI), measured after the standardized KRL 20 hours test at 100° C., of at least 25, and having a viscosity profile comprising :
 (1) the viscosity of said composition, measured at 100° C. after the Bosch-30 cycles test according to the CEC-L-14-A-93 standard representative of the shearing conditions in the engine, is between 15.0 and 20.0 cSt for a grade 50;   (2) the viscosity of said composition, measured at 100° C. after the KRL 20 hours shearing test according to the CEC-L-45-A-99 standard representative of the shearing conditions in the gearbox, is between 11.0 and 14.0 cSt for an oil initially of grade 50; and   (3) the viscosity of said composition measured at 40° C. after the KRL 3 hours shear test, according to the CEC-L-45-A-99 standard, is between 61 and 75 cSt for an oil initially of grade 50.   
   
   
       3 . The lubricating composition according to  claim 2  comprising at least 50 wt. %, based on the weight of the final composition, of at least one oil selected from the oils of groups I to V and at least 5%, preferably from 5 to 40%, or more preferably 5 to 15 wt. %, based on the weight of the final composition, of a mixture comprising at least two different polymers of type “A”, “B”, or “C”, the polymers of the mixture differing from one another in that they belong to a separate range of permanent shear stability index (PSSI) comprising such that:
 the polymers of type “A” have a permanent shear stability index (PSSI), measured after the standardized KRL 20 hours test at 100° C. less than or equal to 40,   the polymers of type “B” have a permanent shear stability index (PSSI); measured after the standardized KRL 20 hours test at 100° C., between 40 and 65 exclusive;   the polymers of type “C” have a permanent shear stability index (PSSI), measured after the standardized KRL 20 hours test at 100° C. greater than or equal to 65; and   the composition in which at least two polymers have a difference in PSSI, measured after the standardized KRL 20 hours test at 100° C., of at least 25.   
   
   
       4 . The lubricating composition according to  claim 3 , wherein each of the polymers of the mixture is obtained from monomer units of a different chemical nature. 
   
   
       5 . The lubricating composition according to  claim 3 , wherein each polymer of the mixture is obtained from monomer units of identical chemical nature, and the polymers of the mixture differ from one another in that they belong to a different range of permanent shear stability index (PSSI) measured after the standardized KRL 20 hours test at 100° C. and by at least one physicochemical characteristic selected from the number-average or weight-average molecular weight, the molecular weight distribution of said polymer is defined by the polydispersity index, the morphology of the three-dimensional network of said polymer is defined by its degree of crosslinking and/or branching. 
   
   
       6 . The lubricating composition according to  claim 3 , wherein, in the mixture comprising at least two polymers, the amount of one polymer relative to the total weight of the polymer mixture ranges from 10% to 90%. 
   
   
       7 . The lubricating composition according to  claim 3 , wherein the mixture comprises two polymers, one of type A and the other of type C. 
   
   
       8 . The lubricating composition according to  claim 7 , wherein the weight ratio of the mixture of the two polymers A/C ranges from 10/90 to 90/10. 
   
   
       9 . The lubricating composition according to  claim 3 , additionally comprising from 5 to 30 wt. %, relative to the weight of the final composition, of a package of functional additives and optionally less than 1 wt. %, preferably from 0.2% to 0.5 wt. %, relative to the weight of the final composition, of a pour point improver. 
   
   
       10 . The lubricating composition according to  claim 3 , wherein the polymers of the mixture are selected from polymers of the viscosity improver type and optionally from polymers of the pour point improver type. 
   
   
       11 . The lubricating composition according to  claim 10 , wherein the viscosity improving polymers are selected from poly-alpha-olefins (PAO) with a kinematic viscosity at 100° C. greater than 90 cSt, poly-isobutenes (PIB), polymeric esters, olefinic copolymers (OCP), homopolymers or copolymers of styrene, of butadiene or of isoprene, polymethacrylates (PMA). 
   
   
       12 . The lubricating composition according to  claim 10 , wherein the pour point improving polymers are selected from polymethacrylates (PMA). 
   
   
       13 . The lubricating composition according to  claim 3 , wherein the polymers of type A are viscosity improving polymers selected from polymethacrylates, poly-alpha-olefins with a kinematic viscosity at 100° C. greater than 90 cSt, polyisobutenes, polymeric esters. 
   
   
       14 . The lubricating composition according to  claim 3 , wherein the polymers of type C are viscosity improving polymers selected from polymethacrylates, olefinic copolymers, hydrogenated styrene-isoprene copolymers, copolymeric esters. 
   
   
       15 . The lubricating composition according to  claim 3 , wherein the polymers of type B are viscosity improving polymers of the polymethacrylate type. 
   
   
       16 . A method of making the lubricating composition, wherein a mixture comprising at least two different polymers is incorporated in at least one oil of groups I to V optionally comprising a package of additives and optionally a pour point improver. 
   
   
       17 . The method according to  claim 16  of making the lubricating composition, wherein at least one of the polymers of the mixture is a viscosity improver which is incorporated directly in the composition as a separate compound, independently of the package of additives. 
   
   
       18 . The method according to  claim 16  of making the lubricating composition, wherein all or part of at least one of the viscosity improving polymers of the mixture is incorporated in the composition as an element of the package of additives. 
   
   
       19 . The method according to  claim 16  of making the lubricating composition, wherein all or part of at least one of the viscosity improving polymers of the mixture is incorporated in the composition in the form of a diluent of the package of additives. 
   
   
       20 . The use of the lubricating composition according to  claim 1 , wherein the composition is a single fluid for lubricating various mechanisms of motor vehicles. 
   
   
       21 . The use according to  claim 20 , wherein the single fluid is used for lubricating at least three mechanisms of motor vehicles: the engine, the gearbox and the hydraulic system of the vehicle. 
   
   
       22 . The use according to  claim 20 , wherein the single fluid is also used for lubricating the circuit for operating the brakes, the on-board compressor and optionally other ancillary mechanisms.