WO2008050003A2 - Multifunctional lubricating fluid - Google Patents

Abstract

The invention 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.

Description

 MULTIFUNCTIONAL LUBRICANT FLUID

Field of the invention

The present invention relates to multifunctional lubricating fluids that can be used in the various components of self-propelled vehicles, in particular in the engine, the transmission or the hydraulic circuit. More specifically, the subject of the invention is a single fluid that can be used directly in several types of application, in particular in the various bodies of self-propelled vehicles such as engines, transmission devices (gearboxes and transfer gearboxes), hydraulic circuits and other secondary organs without modification; in other words, the composition of this fluid is directly adapted for the different types of uses in question.

Technological Background of the Invention

Each self-propelled vehicle currently uses a variety of monofunctional lubricating fluids each fulfilling different functions, for example engine oils, gearbox oils, hydraulic oils, etc. The formulation of a monofunctional oil conventionally consists of a mixture of base oils. mineral, semi-synthetic or synthetic, a package of performance additives, and optionally a viscosity improving polymer and a pour point improver.

When a monofunctional lubricating oil is in use in an organ, the permanent shear experienced by the viscosity improving polymer results in a decrease in the viscosity of the oil. The extent and speed with which this viscosity decrease occurs depends on the nature and amount of viscosity improving polymer used.

However, the shear rates experienced by the lubricant differ from one organ to another. For example, the high-pressure hydraulic systems controlling the lifting devices are more shearing than the gearboxes, themselves more shearing than the engines.

If a monofunctional oil is used in another organ than the one for which it was formulated, its viscosity may deviate from the value required for the optimal functioning of this organ.

Multifunctional oil formulations for engine, gearbox and hydraulic circuit are already marketed under the trade names TOTAL Multi TP, FINA Penta, ELF Noria. Their design is based on a suitable choice of the viscosity improving polymer and its incorporated amount.

The greater or lesser shear stability of the viscosity improving polymer incorporated in these multifunctional oils for engine, gearbox and hydraulic circuit will determine the respective viscosity levels achieved by this oil in each member.

If a viscosity-improving viscosity-improving polymer is used, the viscosity will drop very rapidly, even in the low-shear members: the required minimum viscosities in the engine and gearbox will be reduced.

Conversely, if a very stable shear polymer is used, the viscosity will remain high for a very long time even in the high shear organs: it will take a very long time before the viscosity reaches the best case. a sufficiently low value as requested for example in hydraulic circuits. This can cause long-term cold start problems of the hydraulically controlled lifters.

If the polymer has an intermediate behavior, the adjustment parameters for simultaneously fulfilling the 3 constraints of minimum viscosities in engine and gearbox, and maximum viscosity in hydraulics, are the amount and the nature of the viscosity improving polymer used.

It is on this principle that the majority of the multifunctional oils currently in use are based. This leads to compromises that exceed the limits of the capacity of use of current multifunctional oils in three organs at a time. Thus, current formulations of multifunctional oils do not allow them to achieve the expected performance levels in the various organs targeted at once. In addition, the performance levels are not achieved with particular regard to the heat resistance in the engines and the transmission and the cold start of the hydraulics. There is therefore a need for a single fluid whose performance is adapted to lubricate at the same time different organs of a vehicle. In particular, there is a need for a single fluid usable for all three applications that are the engine, the transmission and the hydraulic circuit. There is also a need to adapt the performance of this same single fluid for good heat resistance in the engines and transmission and for the cold start of the hydraulic. Indeed, the fact of having a single fluid to lubricate different organs of a vehicle, compared to the use of several monofunctional oils, has advantages especially in terms of ease of maintenance and storage, maintenance of the vehicle or fleet of vehicles, packaging and logistics.

This is particularly true for large fleets of public works vehicles, which are often used on isolated sites and subjected to bad weather conditions and lacking adequate storage facilities.

Summary of the invention. Thus the invention provides a lubricating composition comprising at least one Group I to V oil and a mixture of at least two polymers having a difference in Shear Stability Index (PSSI), measured after KRL normalized test 20 hours at 100 ⁰ C of at least 25, and having a viscosity profile such that (a) at 100 ⁰ C after Bosch-30 cycles test according to CEC-L-14-A-93 the viscosity of the final lubricating composition is greater than 9.0 cSt, preferably in the range of 9.0 to 12.0 cSt for a starting oil of grade 30, or 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 starting from grade 40, and (b) at 100 ⁰ C after KRL test -20 hours according to CEC-L-45-A-99 the viscosity of the lubricating composition is greater than 8.5 cSt, preferably in the range of 8.5 to 11, OcSt for an oil from g 30 or 40, and

(c) at 40 ^° C. after the KRL-3 hours test, according to the CEC-L-45-A-99 standard, the test duration of which is reduced to 3 hours, the viscosity of the lubricating composition is less than 51 cSt, preferably in the range from 41 to 50 psig for an oil starting from grade 30 or 40.

This formulation of multifunctional lubricant can be used to lubricate at the same time different organs of a self-propelled vehicle. More particularly, this unique lubricant serves to lubricate at least the three components that are the engine, the gearbox and the hydraulic circuit, because it has a viscosity profile adapted to the conditions of use required in each target organ.

To lubricate both the different target organs of a self-propelled vehicle, this unique lubricant incorporates a blend of polymers having different shear stabilities. The nature and the respective amount of the different types of polymers are determined so that the lubricating composition incorporating this mixture adapts very quickly to the required conditions of use in each target organ and this thanks to its viscosity profile.

Thus, the lubricating composition comprises at least 50% by weight relative to the weight of the final composition of at least one oil chosen from oils of groups I to V and at least 5%, preferably from 5 to 40%, or preferably 5 to 15% by weight, based on the weight of the final composition, of a mixture comprising at least two different polymers of type "A", "B", or "C", each of the polymers of the mixture differing from one another others by their belonging to a distinct range of permanent index of stability in shear (PSSI) such that: -the polymers of type "A" have a permanent index of stability in shear

(PSSI), measured after standardized test KRL 20 hours at 100 ⁰ C less than or equal to 40,

the polymers of type "B" have a peπnanent index of stability in shear (PSSI), measured after standardized test KRL 20 hours at 100 ⁰ C between 40 and 65 excluded terminals; the "C" type polymers have a permanent index of stability in shear

(PSSI), measured after standardized test KRL 20 hours at 100 ⁰ C greater than or equal to 65; said composition in which at least two polymers have a difference in PSSI measured after standardized test KRL 20 hours at 100 ⁰ C, of at least 25.

According to one embodiment, each of the polymers of the mixture is obtained from monomeric units of a different chemical nature.

According to another embodiment, each polymer of the mixture is obtained from monomeric units of the same chemical nature, and each polymer of the mixture is differentiated from each other by its belonging to a distinct range of permanent stability index. in shear (PSSI) measured after standardized test KRL 20 hours at 100 ⁰ C and by at least one physico-chemical characteristic selected from the number-average molecular weight or by weight, the molecular weight distribution of said polymer characterized by the polydispersity, the morphology of the three-dimensional network of said polymer characterized by its degree of crosslinking and / or branching. According to one embodiment, the mixture comprises at least two polymers, the amount of a polymer based on the total weight of the polymer mixture ranges from 10% to 90%.

According to one embodiment, the mixture comprises two polymers, one of type A and the other of type C, in which, preferably, the ratio by weight of the mixture of the two polymers A / C ranges from 10/90 to 90 / 10.

According to one embodiment, the lubricating composition according to the invention further comprises from 5 to 30% by weight relative to the weight of the final composition. a package of functional additives and optionally less than 1% by weight, preferably from 0.2% to 0.5% by weight relative to the weight of the final composition of a pour point improver.

According to one embodiment, the polymers of the mixture are chosen from viscosity-improving type polymers and possibly from the type of pour point-type polymers.

Preferably, the viscosity improving polymers are chosen from

Α-Alpha olefins (PAO) with a kinematic viscosity at 100 ° C. of greater than 90 cSt, the

Poly-Isobutenes (PIB), Polymeric Esters, Olefins Copolymers (OCP), homopolymers or copolymers of styrene, butadiene or isoprene, polymethacrylates (PMA).

Preferably, the pour point-improving polymers are chosen from polymethacrylates (PMA).

Preferably, the type A polymers are viscosity improving polymers chosen from polymethacrylates, polyalphaolefms having a kinematic viscosity at 100 ^° C. of greater than 90 cSt, polyisobutenes and polymer esters.

Preferably, the type C polymers are viscosity improving polymers chosen from polymethacrylates, olefin-co-polymers, hydrogenated styrene-isoprene copolymers and copolymeric esters. Preferably, the B-type polymers are polymethacrylate-type viscosity improving polymers.

According to another object, the invention relates to a process for manufacturing a lubricant composition according to the invention in which a mixture comprising at least two different polymers is incorporated in at least one group I to V oil optionally comprising a package of additive and optionally a pour point improver.

According to one embodiment, at least one of the polymers of the mixture is a viscosity improver which is incorporated directly into the composition as a separate compound, independently of the additive package. According to another embodiment of the process, all or part of at least one of the viscosity improving polymers of the mixture is incorporated into the composition as part of the additive package.

According to another embodiment of the process, all or part of at least one of the viscosity improving polymers of the mixture is incorporated into the composition in the form of a diluent of the additive package. According to another object the invention relates to the use of a lubricant composition according to the invention as a single fluid for lubricating various bodies of self-propelled vehicles.

Preferably, the single fluid serves to lubricate at least three bodies of self-propelled vehicles, the engine, the gearbox and the hydraulic system of the vehicle.

More preferably, the single fluid also serves to lubricate the brake control circuit, the onboard compressor and possibly other secondary organs. DETAILED DESCRIPTION OF THE EMBODIMENTS OF THE INVENTION

(A) Determination of shear stability:

The shear stability of a compound in an oil is characterized by the

PSSI (Permanent Shear Stability Index, or Shear Stability Index)

Permanent), defined in ASTM-D6022-06 and calculated from the kinematic viscosities of said compound in the oil before and after a determined shearing process.

The formula of the PSSI of a polymer in an oil is given by: PSSI = 100 x (Vi - Vc) / (Vi - Vo), where: • Vi = initial viscosity before shear of the oil + polymer mixture at

100 ⁰ C.

• Vc = viscosity of the oil + polymer mixture after shearing process at 100 ^° C.

• Vo = initial viscosity before shear of the oil alone at 100 ^° C. Thus, the higher the PSSI of a polymer in the reference oil, the more said polymer is said to be sensitive to shear.

The shearing process chosen to determine the PSSI of the polymers according to the present invention is the KRL 20 hours test, according to the CEC-L-45-A-99 standard.

The reference oil chosen for measuring the PSSI of the polymers according to the present invention is a Group III (API classification) base oil with a viscosity of 4.2 cSt at 100 ^° C.

In the remainder of the text and in the absence of contrary details, the PSSI of a polymer will be the PSSI measured according to the standard ASTM-D6022-06, measured in a dilution oil of group III (according to API classification and viscosity 4.2 cSt at 100 ^° C., after KRL test 20 hours, according to standard CEC-L-45-A-99).

In order to determine the composition of the polymer blends incorporated in the lubricants according to the present invention, the Applicant has defined the conditions of shear representative of each of the organs and viscosity levels adapted to each organ.

(B) Determination of the viscosity profile. 1. Conditions of Use as Engine Oil: For engine lubricants, the CEC-L-14-A-93 (or ASTM D6278) standard defines the test representative of shear conditions in the engine, referred to as Bosch-30 cycle test.

The SAE J 300 classification defines the viscosity grades of new motor oils, in particular by measuring their kinematic viscosities at 40 ^° C. and / or 100 ° C.

A motor oil is grade 30 according to SAE J 300 if its kinematic viscosity at 100 ⁰ C is between 9.3 and 12.5 cSt.

A motor oil is grade 40 according to SAE J 300 if its kinematic viscosity at 100 ⁰ C is between 12.5 and 16.3 cSt. Engine oils of grade 30 or 40 are generally used in so-called temperate climates.

A motor oil is grade 50 according to SAE J 300 if its kinematic viscosity at 100 ⁰ C is between 16.3 and 21.9 cSt. This type of oil is generally used in so-called hot climates. The ACEA standards define in detail a certain number of additional specifications for engine oils, and in particular require the maintenance of a certain level of viscosity for the oils in operation subjected to shear in the engine.

Thus, according to the ACEA E2 or E3 sequence, the kinematic viscosity of the grade 30, 40 and 50 motor oils, measured at 100 ° C., after the Bosch-30 cycle test, must be greater than 9.0, 12.0 and 15.0 cSt.

The lubricants according to the present invention which can be used as engine lubricants have a kinematic viscosity at 100 ^° C. of greater than 9.0 cSt, preferably in the range of 9.0 to 12.0 cSt after the Bosch-30 cycle test according to the CEC-standard. L-14-A-93 for an oil starting from grade 30. These lubricants have a kinematic viscosity at 100 ^° C. of greater than 12.0 cSt, preferably in the range from

12.0 to 15.0 cSt after the Bosch-30 cycles test according to the CEC-L-14-A-93 standard for an oil starting from grade 40. After this same test, these lubricants have a kinematic viscosity at 100 ⁰ C which is greater than 15.0 cSt, preferably in the range of 15.0 to 20.0 cSt for a grade 50 oil.

2. Conditions of use as gearbox oil: For gearbox lubricants, CEC-L-45-A-99 defines the test representative of the shear conditions in the gearbox, known as the 20-hour KRL test.

The Applicant has determined from the oil monitoring test data in use that a viscosity of a lubricant at 100 ° C after the 20-hour KRL standard test greater than 8.5 cSt was suitable for use in gearboxes in temperate climates. Moreover, a viscosity of a lubricant at 100 ^° C. after standardized test KRL

20 hours above 11.0 cSt was suitable for use in hot climates.

3. Conditions of Use as Hydraulic System Oil: The Applicant has also determined that the shear conditions experienced by a lubricant in a hydraulic circuit could be represented by the KRL test according to the CEC-L-45-A-99 standard.

The Applicant has observed that to operate in the hydraulic circuit by overcoming the problem of starting with new oil, especially at low temperatures, the viscosity of the lubricant, measured at 40 ^° C., should be less than 51 cSt for temperate climates after KRL test according to CEC-L-45-A-99 whose duration is reduced from 20 hours to 3 hours. Similarly, the viscosity of the lubricant should be less than 75cSt for hot climates after KRL test according to CEC-L-45-A-99 whose duration is reduced from 20 hours to 3 hours. Thus, the lubricant compositions according to the present invention are suitable both for use in engines, transmissions, and hydraulic circuits because they have a viscosity profile that meets the following three cumulative conditions:

(a) at 100 ^° C. after the Bosch-30 cycles test according to CEC-L-14-A-93 the viscosity of the final lubricating composition is greater than 9.0 cSt, preferably in the range of 9.0 at 12.0 cSt for an oil starting from grade 30, or the viscosity of the final lubricating composition is greater than 12.0 cSt, preferably in the range of 12.0 to 15.0 cSt for an oil at departure of grade 40, and

(b) at 100 ^° C. after KRL test 20 hours according to CEC-L-45-A-99 the viscosity of the lubricating composition is greater than 8.5 cSt, preferably in the range from 8.5 to 11 , OcSt for an oil starting from grade 30 or 40, and

(C) at 40 ^° C. after the KRL test for 3 hours, according to the CEC-L-45-A-99 standard, the test duration of which is reduced to 3 hours, the viscosity of the lubricating composition is less than 51 cSt, preferably in the range of from 41 to 50 cSt for an oil starting from grade 30 or 40.

Under these conditions, these compositions are particularly suitable for temperate climates. According to one particular embodiment, the lubricant compositions according to the present invention are also usable in hot climates and also respect the following conditions:

(1) the viscosity of said composition, measured at 100 ^° C., after Bosch-30 cycles test according to the CEC-L-14-A-93 standard representative of the engine shear conditions, is between 15.0 and 20.0 cSt for a grade 50;

(2) the viscosity of said composition, measured at 100 ^° C. after a 20-hour KRL shear test according to the CEC-L-45-A-99 standard representative of shear conditions in a gearbox, is between 11.0 and 14.0 cSt for an oil starting from grade 50;

(3) the viscosity of said composition measured at 40 ^° C. after the KRL shear test for 3 hours, according to the CEC-L-45-A-99 standard, is between 61 and 75 cSt for a starting oil of grade 50.

These conditions are determined by kinematic viscosity measurements expressed in centistokes cSt (or equivalent mm ² / s) and according to known methods and whose standards are referenced earlier in the text. (C) Basic oils:

The base oils used in the formulation of lubricants according to the present invention are oils of groups I to V according to API classification, of mineral origin, synthetic or natural, used alone or as a mixture, one of the characteristics of which is to be insensitive to shear, that is to say that their viscosity is not modified under shear. They represent in the composition at least 50% by weight, based on the total weight of the final composition. In addition, their content may represent up to 95% or even 98% in the final composition. (D) The package of additives:

The additive packages used in the lubricant formulations according to the invention are conventional and also known to those skilled in the art and meet performance levels defined inter alia by F ACEA (Association of European Automobile Manufacturers) and / or TAPI. (American Petroleum Institute). They contain in particular and without limitation:

Antioxidants that prevent the degradation of the oil (for example amino or phenolic derivatives)

• anti-wear and extreme pressure agents protecting the friction surfaces by chemical reaction with the metal surface, (for example zinc dithiophosphate),

Dispersants ensuring the suspension and evacuation of insoluble solid contaminants (for example PBS succinimide), • detergents overbased or not, avoiding the formation of deposits on the surface of metal parts by dissolving secondary oxidation and combustion products, (eg salicylates, phenates or sulfonates). and at least 30% by weight of a diluent consisting of base oil and optionally viscosity improving polymer.

The weight percentage of additive package based on the weight of the final composition according to the invention is at least 5%, the diluent being included in this percentage.

(E) The so-called "pour point improver" compounds.

The lubricant formulations according to the invention optionally comprise a pour point improver, which may be chosen from the group of polymethacrylates (PMA) with molecular masses generally of between 5,000 and 10,000 daltons. It should be noted that these PMAs, when used as additive pour point additives, are typically present in the lubricating composition at levels of the order of 0.2% by weight, based on the weight of the final lubricating composition. These pour point depressant additives are generally provided as more or less dilute formulations in a base oil. In particular, when these formulations are not very diluted, the PMAs are present at contents of about 60%.

Their use in the polymer blend of the present invention to adjust the viscosity of the lubricant to a certain level after shearing may require the use of higher levels.

(F) The polymer mixture in the lubricating composition.

The aforementioned viscosity profile is especially obtained thanks to a mixture of at least two polymers chosen from polymers of types "A" "B" or "C" as defined below:

The polymers of types "A""B""C" used in a mixture in the lubricants according to the present invention are preferably chosen from the viscosity index or pour point improving improving polymers as described above. The viscosity improving polymers used in the present invention correspond to those used in monofunctional oils. They are preferably chosen from poly-alpha-olefins (PAO) with a kinematic viscosity at 100 ^° C. of greater than 90 cSt, poly-isobutenes (PIB), polymer esters, olefins copolymers (OCP), homopolymers or copolymers of styrene, butadiene or isoprene, polymethacrylates (PMA).

The pour point-improving polymers used in the present invention are preferably selected from polymethacrylates (PMA). In general, a viscosity improving polymer is intended to reduce lubricant viscosity variations with temperature. This temperature behavior is characterized by the viscosity index or VI

(Viscosity Index) lubricant. A high V.I. oil will have better viscosity stability as a function of temperature.

The polymers incorporated in the lubricants according to the present invention have been classified in three groups according to their belonging to a distinct range of PSSI:

1) The group of polymers of type "A" comprises polymers which have a permanent index of stability in shear (PSSI), measured after standardized test KRL 20 hours at 100 ⁰ C less than or equal to 40. These polymers are insensitive to shear: these are polymers whose PSSI after standardized test KRL 20 hours to

100 ⁰ C is less than or equal to 40, preferably 0 to 20. This type of polymer will maintain the viscosity at a sufficient level in the engine and in the gearbox, but will also allow the viscosity to drop significantly in hydraulics.

In the group of polymers of type "A", there will be found, in particular and without limitation, viscosity improvers chosen from viscous polyalphaolefins (PAO) (with a viscosity at 100 ^° C. of greater than 90 cSt), polyisobutenes (PIB), polymethacrylates (PMA). More specifically, type A polymers are viscosity-improving polymers chosen from polymethacrylates (Viscoplex 0-030, 0-110, 6-054, 8-220, 12-310) and viscous polyalphaolefins (Spectrasyn 1000,300,150). polyisobutenes (Indopole 2100, Lubrizol 3174), polymeric esters (Kenjetlube 2700).

2) The group of "B" type polymers includes polymers that have a permanent shear stability index (PSSI), measured after standardized test

KRL 20 hours at 100 ⁰ C between 40 and 65 terminals excluded. These polymers of intermediate behavior are said to be sensitive to shear: they are polymers whose PSSI after standardized test KRL 20 hours at 100 ° C is between 40 and 65 excluded terminals. This type of polymer will provide the complement by improving viscosity if necessary.

In the group of "B" -type polymers, polymethacrylate-type viscosity improvers (Viscoplex 0-220, 3-500, 8-400, 8-251, 8-310) are especially suitable.

3) the group of polymers of type "C" includes polymers which have a permanent index of stability in shear (PSSI), measured after standardized test

KRL 20 hours at 100 ⁰ C greater than or equal to 65. These polymers are very sensitive to shear: they are polymers whose PSSI after standardized test KRL 20 hours to 100 ^° C. is greater than or equal to 65, preferably 65 to 100. This type of polymer will shear very rapidly in hydraulics, with a subsequent and lasting viscosity drop of the lubricant in this organ, thus avoiding low starting problems. temperature. In the group of "C" -type polymers, there are, in particular and without limitation, the viscosity-improving polymers chosen from the category of copolymer olefins, homopolymers or copolymers of styrene, butadiene, or isoprene. More specifically, the type C polymers are viscosity-improving polymers chosen from polymethacrylates (Viscoplex 7-710), olefin-co-polymers (Paratone 8006, Lubrizol 7077) and hydrogenated styrene-isoprene copolymers (Shellvis 151, 201, 261 and 301), the copolymeric esters (Lubrizol 3702.

Thus, the viscosity profile of the composition according to the invention is obtained when at least two polymers of the mixture are chosen from distinct ranges of PSSIs.

The polymer mixtures used in the invention consist of at least two polymers, each polymer of the mixture being differentiated from each other by its belonging to a distinct range of permanent shear stability index (PSSI) measured after standardized test KRL 20 hours at 100 ⁰ C. This distinction is characterized by the existence of a difference of PSSI of at least 25 between the PSSI of at least two of the polymers present in the mixture.

Moreover, the shear strength of a polymer is not exclusively related to its chemical nature. It can also be linked to physicochemical parameters. Indeed, parameters such as molecular weights, their distribution (characterized in particular by the polydispersity index of the polymer), the degree of branching of the polymer chains, and in general the morphological characteristics of the polymer have an impact on its shear strength. . Thus, certain compounds of the same chemical nature, such as polymethacrylates for example, can be found in any of the types "A", "B", or "C" described herein.

Therefore, those skilled in the art will choose polymers of different types to be used in the mixture according to their classification according to type A, B or C and their ability to obtain a lubricating composition which respect the three cumulative conditions such as described above in the targeted viscosity profile. This viscosity profile is also obtained when the polymers of the mixture are differentiated either by their chemical nature or by their physicochemical nature. Thus, when the polymers of the mixture are differentiated by their chemical nature, this differentiation comes from the preparation of the polymers from monomeric units of distinct chemical nature. For example, a polymethacrylate is chemically different from a polyisobutene. When the polymers of the mixture are differentiated by their physicochemical nature, this differentiation comes from the preparation of the polymers from monomeric units of the same chemical nature. In this case, each polymer of the mixture is differentiated by its belonging to a distinct range of permanent shear stability index (PSSI) and also by at least one physico-chemical characteristic chosen from the average molecular mass (in number or in weight ) or the molecular weight distribution of said polymer characterized by its polydispersity index or the morphology of the three-dimensional network of said polymer characterized by its degree of crosslinking and / or branching. These differentiations of physico-chemical nature are implemented according to techniques well known in the field of polymers.

According to a particular embodiment, the compositions according to the invention comprise a mixture in all proportions of two polymers of A / B or A / C or B / C type. preferably, in this mixture, the amount by weight of one of the polymers of type A or B or C based on the total weight of polymer in the mixture ranges from 10 to 90%. According to one preferred embodiment the compositions comprise a mixture of two polymers of type A and C in which the ratio by weight A / C ranges from 10/90 to 90/10.

According to another particular embodiment, the compositions according to the invention comprise a mixture in all proportions of the three polymers A, B and C. In this mixture, the amount by weight of one of the polymers of type A or B or C relative to the weight total of the polymers in the mixture can be at least 10% and at most 80%. Thus, it is preferable to have A / B / C mixtures whose weight ratios are 10/10/80 or 10/80/10 or 80/10/10 and all intermediate ratios.

According to one embodiment, the compositions according to the invention comprise a mixture of the three polymers A, B and C in which the polymer A is present in an amount of 30 to 45% by weight, the polymer B is present in an amount of 1 to 20% by weight and the polymer C is present in an amount of 30 to 45% by weight, these% being expressed relative to the total weight of the polymers.

More particularly, the polymer mixtures used in the invention as defined above represent at least 5%, preferably 5 to 40%, preferably 5 to 15% by weight, based on the weight of the final lubricating composition. According to one embodiment, the minimum amount of a polymer based on the total weight of the final composition is 1%.

In the field of lubricants all these percentages generally correspond to polymers which comprise at least 5% of polymer active material, the balance being represented by a base oil used as a diluent. Moreover, in some cases when the polymer requires little or no dilution (for example PAO), these percentages may be up to 100% of active polymer material.

Therefore, these lubricants adapt very quickly to the conditions of use required in each organ.

To prepare the lubricating composition according to the invention, a mixture of at least two polymers of type A, B or C in at least one group I to V oil is generally incorporated at a temperature of between 20 and 100 ^° C. and atmospheric pressure. optionally comprising an additive package and optionally a pour point improver.

The polymers of type "A", "B" or "C" according to the present invention may be incorporated into the composition as a separate component, or may be introduced as a component of the additive package, as an additive or diluent .

Thus, the lubricating compositions according to the invention are prepared by incorporating at least one of the type A, B, or C viscosity improving polymers directly into the composition as a separate additive, independently of the additive package.

In another embodiment, all or part of at least one of the A, B, or C viscosity improving polymers is incorporated into the lubricant as part of an additive package.

According to another embodiment, all or part of at least one of the viscosity improving polymers of type A, B or C is incorporated in the lubricant in the form of a diluent of the additive package.

The compositions according to the invention are used as a single lubricant in various members of self-propelled vehicles at a time, in particular members whose shear rates differ. Thus the compositions according to the invention have particularly well-suited performance for good hot performance in engines and transmission and for the cold start of the hydraulics.

Examples: The following examples are intended to illustrate the invention without limiting its scope.

The mixtures are made with stirring at 80 ⁰ C in 1 liter flasks. ASTM D445 is used for determining viscosities Two lubricant samples were prepared, grade 40 and 30, respectively, according to the SAE J 300 classification.

Example 1

A lubricant containing 50% by weight of a Group IV base oil of viscosity 2 cSt at 100 ^° C. and 14.25% by weight of a commercial additive package referenced in the supplier 1 was prepared. Additive package is free of "A", "B" or "C" type polymers according to the present invention, and the diluent consists of base oil.

A mixture consisting of: 31% by weight of a polyalphaolefin type "A" according to the present invention, having a PSSI of 6 and

4.75% by weight of a formulation containing 35% of active material represented by a "C" type copolymer ester according to the present invention, having a PSSI of 93. The lubricant thus prepared is grade 40 according to the classification SAE J300 .

Example 2

A lubricant containing 77.5% by weight of a Group IV base oil of 4.2 cST viscosity at 100 ^° C., and 14.50% by weight of a commercial additive package referenced in US Pat. 2. This additive package is free of type "A", "B" or "C" polymers according to the present invention and the diluent consists of base oil.

Then added in said lubricant a mixture consisting of:

3.5% by weight of an "A" type heavy polyolefin olefin according to the present invention, having a PSSI of 35, and 1% by weight of a formulation containing 63% of active material represented by a PMA polymer of type "B" according to the present invention, having a PSSI of 63, and

3.5% by weight of a formulation containing 10.8% of active material represented by a hydrogenated styrene-isoprene copolymer type "C" according to the present invention, having a PSSI of 90. The lubricant thus prepared is of grade 30 according to SAE J300 classification.

The following table gives the viscosity values in cSt of these two lubricating compositions: at 100 ^° C. after KRL test -20 hours according to CEC-L-45-A-99, at 100 ^° C. after Bosch-30 cycles test. according to the CEC-L-14-A-93 standard, at 40 ^° C. after KRL-3 hours test, according to standard CEC-L-45-A-99, the test duration of which is reduced to 3 hours. Table I:

Spectrasyn 150 is a PoIy alpha olefin (PAO)

Spectrasyn 1000 is a PoIy alpha olefin (PAO)

Lz 3702 is a copolymer ester

Viscoplex 8-400 is a polymethacrylate

SV 261 is a hydrogenated styrene-butadiene copolymer

The additive packages from suppliers 1 and 2 are packets of commercial engine oil additives diluted in Group I to III oils comprising no type A, B or C polymers according to the present invention.

In particular, these packets make it possible to formulate engine lubricants having performances at level E3 of the ACEA.

Claims

A lubricating composition comprising at least one group I to V and a mixture of at least two polymers having a difference in permanent shear stability index (PSSI), measured after standardized test KRL 20 hours at 100 ^° C. of at least 25, and having a viscosity profile such that (a) at 100 ^° C. after the Bosch-30 cycles test according to CEC-L-14-A-93 the viscosity of the final lubricating composition is greater than 9.0 cSt, preferably in the range of 9.0 at 12.0 cSt for an oil starting from grade 30, or the viscosity of the final lubricating composition is greater than 12.0 cSt, preferably in the range of 12.0 to 15.0 cSt for an oil at departure 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 greater than 8.5 cSt, preferably in the range from 8.5 to 11, OcSt for an oil starting from grade 30 or 40, and (c) at 40 ^° C. after the KRL-3 hours test, according to the CEC-L-45-A-99 standard, the test duration of which is reduced to 3 hours, the viscosity of the lubricating composition is less than 51 cSt, preferably in the range from 41 to 50 psig for an oil starting from grade 30 or 40. 2. Lubricating composition comprising at least 50% by weight relative to the weight of the final composition of at least one oil chosen from oils of groups I to V and at least 5%, preferably from 5 to 40%, or preferably 5 to 15% by weight, based on the weight of the final composition, of a mixture comprising at least two different polymers of type "A", "B", or "C", each of the polymers of the mixture differing from each other. other by their belonging to a distinct range of Permanent Shear Stability Index (PSSI) such as: the polymers of type "A" have a permanent shear stability index (PSSI), measured after standardized test KRL 20 hours at 100 ^° C. of less than or equal to 40, the "B" type polymers have a permanent index of stability in shear (PSSI), measured after standardized test KRL 20 hours at 100 ⁰ C between 40 and 65 excluded terminals; the polymers of type "C" have a permanent index of stability in shear (PSSI), measured after standardized test KRL 20 hours at 100 ⁰ C greater than or equal to 65; said composition in which at least two polymers have a difference in PSSI measured after standardized test KRL 20 hours at 100 ⁰ C, of at least 25. The lubricating composition of claim 2 wherein each of the polymers of the mixture is obtained from monomeric units of a distinct chemical nature. The lubricating composition according to claim 2 or 3 wherein each polymer of the mixture is obtained from monomeric units of the same chemical nature, and each polymer of the mixture is differentiated from each other by its belonging to a distinct range of permanent shear stability index (PSSI) measured after standardized test KRL 20 hours at 100 ^° C. and by at least one physicochemical characteristic chosen from the number-average or weight-average molecular mass, the molecular weight distribution of said polymer characterized by the polydispersity index, the morphology of the three-dimensional network of said polymer characterized by its degree of crosslinking and / or branching. 5. Lubricating composition according to one of claims 2 to 4 wherein, in the mixture comprising at least two polymers, the amount of a polymer based on the total weight of the polymer mixture ranges from 10% to 90%. 6. Lubricating composition according to one of claims 2 to 5 wherein the mixture comprises two polymers, one type A and the other type C. 7. Lubricating composition according to claim 6 wherein the ratio by weight of the mixture of the two polymers A / C ranges from 10/90 to 90/10. 8. Lubricating composition according to one of claims 2 to 7 further comprising from 5 to 30% by weight relative to the weight of the final composition of a functional additive package and optionally less than 1% by weight, of preferably from 0.2% to 0.5% by weight based on the weight of the final composition of a pour point improver. 9. Lubricating composition according to one of claims 2 to 8 wherein the polymers of the mixture are selected from the viscosity-improving type polymers and optionally from the type of pour point-type polymers. 10. Lubricating composition according to claim 9 wherein the viscosity improving polymers selected from poly-alpha-olefins (PAO) kinematic viscosity at 100 ⁰ C greater than 90 cSt, poly-lsobutenes (PIB), Polymer Esters, Olefins Copolymers (OCP), homopolymers or copolymers of styrene, butadiene or isoprene, polymethacrylates (PMA). The lubricating composition of claim 9 wherein the pour point improver polymers are selected from polymethacrylates (PMA). 12. Lubricating composition according to one of claims 2 to 11 wherein the type A polymers are viscosity improving polymers selected from polymethacrylates, polyalphaolefins kinematic viscosity at 100 ⁰ C greater than 90 cSt, polyisobutenes, esters polymers. 13. Lubricating composition according to one of claims 2 to 11 wherein the type C polymers are viscosity improving polymers selected from polymethacrylates, olefin-Co-Polymers, hydrogenated styrene-isoprene copolymers, copolymer esters. 14. Lubricating composition according to one of claims 2 to 11 wherein the type B polymers are polymers improving polymethacrylate viscosity type. 15. Lubricating composition according to one of claims 2 h 14 having the characteristics defined in claim 1. 16. A method of manufacturing a lubricant composition according to one of claims 1 to 15 wherein is incorporated a mixture comprising at least two different polymers in at least one oil groups I to V optionally comprising an additive package and optionally a pour point improver. 17. The manufacturing method according to claim 16 of a lubricating composition according to any one of claims 1 to 15 wherein at least one of the polymers of the mixture is a viscosity improver which is incorporated directly into the composition as a separate compound regardless of the additive package. 18. The manufacturing method according to claim 16 of a lubricating composition according to any one of claims 1 to 14 wherein all or part of at least one of the viscosity improving polymers of the mixture is incorporated into the composition as a element of the additive package. 19. The manufacturing method according to claim 16 of a lubricant composition according to one of claims 1 to 15 wherein all or part of at least one of the viscosity improving polymers of the mixture is incorporated into the composition as a diluent of the additive package. 20. Use of a lubricant composition according to any one of claims 1 to 15 as the sole fluid for lubricating various bodies of self-propelled vehicles. 21. Use according to claim 20 wherein the single fluid is used to lubricate at least three bodies of self-propelled vehicles, the engine, the gearbox and the hydraulic system of the vehicle. 22. Use according to claim 20 or 21 wherein the single fluid is also used to lubricate the brake control circuit, the onboard compressor and possibly other secondary organs.