WO2009125075A1 - Multipurpose lubricant fluid - Google Patents

Abstract

The present invention relates to multipurpose lubricant fluids that can be used in the various units of automotive vehicles, especially in the engine, the transmission or the hydraulic circuit and relates to a lubricating composition that comprises at least one base oil from Groups I to II, and a mixture of at least two polymers having a difference in the permanent shear stability index (PSSI), measured after a standardized KRL test of 20 hours at 100°C, of at least 25 and that has a viscosity profile such that: (a') at 100°C, before shear, the kinematic viscosity of the new lubricating composition is greater than 15.0 cSt, preferably 15.5 cSt and less than 16.3 cSt; (a) at 100°C after a Bosch test of 30 cycles according to the CEC-L-14-A-93 standard, the kinematic 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; (b) at 100°C after a KRL test of 20 hours according to the CEC-L-45-A-99 standard, the viscosity of the lubricating composition is greater than 10.0 cSt, preferably in the range from 10.0 cSt to 12.5 cSt, for an oil initially of grade 40; and (c) at 40°C after a KRL test of 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 between 61 and 75 cSt, for an oil initially of grade 40.

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 mineral, semi-synthetic or synthetic base oils, a package of performance additives, and optionally a viscosity improving polymer and a viscosity improving agent. pour point.

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. In particular, in hot countries, the oil can be subjected to severe thermal stresses.

The new oil must therefore have a high kinematic viscosity, in order to withstand high external temperatures, and keep a sufficient viscosity after shear in the engine and the gearbox, while remaining sufficiently fluid to be acceptable in the hydraulic circuit.

In addition, in order to have economically viable solutions in these same countries, the use of formulations based on Group I and II is preferred. Given their low viscosity index, typically less than 110, it is impossible to formulate, from the bases of group I and / or II, multifunctional oils according to the concepts of the prior art, that is to say by adding an improving polymer of VI index.

There is therefore a need for multifunctional oils adapted to the specifications of hot countries and formulated from Group I and / or IL oils.

The fact of having a single fluid for lubricating different parts of a vehicle, compared to the use of several monofunctional oils, has advantages in particular in terms of ease of maintenance and storage, vehicle maintenance or maintenance. a 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 II base oil, and a blend of at least two polymers having a Shear Stability Index (PSSI) difference, measured after KRL standardized test. 20 hours at 100 ^° C. of at least 25, and having a viscosity profile such that: (a ¹ ) at 100 ^° C., before shearing, the kinematic viscosity of the new lubricating composition is greater than 15.0 cSt, preferably 15.5 cSt, and less than 16.3 cSt,

(a) at 100 ^° C. after the Bosch-30 cycles test according to CEC-L-14-A-93, the kinematic viscosity of the final lubricating composition is greater than 12.0 cSt, preferably in the range of 12.0 to 15.0; , 0 cSt, for an oil starting from grade 40, (b) at 100 ° C after KRL -20 hours according to CEC-L-45-A-99 the viscosity of the lubricating composition is greater than 10.0, preferably in the range of 10.0 to 12 , 5, for an oil starting from grade 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 between 61 and 75; cSt, for an oil starting from grade 40. Alternatively, the invention provides a lubricating composition comprising at least one Group I to II base oil, and a mixture of at least two polymers having a permanent index difference. of shear stability (PSSI), measured after standardized test KJRJL 20 hours at 100 ° C of at least 25, and having a viscosity profile such that:

(a ') at 100 ° C, before shear, the kinematic viscosity of the new lubricant composition is greater than 16.3 cSt and less than 21.9 cSt,

(a) at 100 ° C. after the Bosch-30 cycles test according to CEC-L-14-to-93, the kinematic viscosity of the final lubricating composition is greater than 15.0 cSt, preferably in the range from 0 to 20.0 cSt, for an oil starting from grade 50,

(b) at 100 ° C after KRL -20 hours according to CEC-L-45-A-99 the viscosity of the lubricating composition is greater than 10.0 cSt and strictly less than 11.0 cSt, preferably lower than or equal to 10.9 cSt, for an oil starting from grade 50, 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 between 61 and 75; cSt, for an oil starting from grade 50. This formulation of multi functional 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. In order 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 conditions of use required 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 one or more base oils, of which at least one oil chosen from oils of groups I to II and at least 5%, preferably from 5 to 40%, or even more preferably 5 to 15% by weight relative to the weight of the final composition, of a mixture comprising at least two different polymers of type "A", "B", or "C", each of Polymers of the mixture differing from each other by their belonging to a distinct range of Permanent Shear Stability Index (PSSI) such as:

the polymers of type "A" have a permanent index of stability in shear (PSSI), measured after standardized test KRL 20 hours at 100 ° C lower 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 ° 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.

Preferably, the lubricating composition comprises at least 50%, preferably at least 70% by weight of one or more base oils chosen from Group I to IL oils.

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 physicochemical characteristic selected 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.

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 lubricant composition according to the invention further comprises 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.

According to one embodiment, the polymers of the mixture are selected from improvers polymers of viscosity, also known as polymeric viscosity index improver or VI improver and optionally from ₅ improvers polymers pour point. Preferably, the viscosity improving polymers are chosen from

Α-Alpha olefins (PAO) having a kinematic viscosity at 100 ° C. of greater than 90 cSt, polyisobutenes (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, polyalphaolefins 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 method 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 II 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), 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 PSSI formula of a polymer in an oil is given by:

PSSI = 100 x (Vi - Vc) / (Vi - Vo), where:

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

100 ° C.

• Vo = initial viscosity before shearing 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 I (API classification) base oil with a viscosity of 3.53 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 group I dilution oil (according to the API classification and with a viscosity of 3.53 cSt at 100 ^° C., after a KRL test of 20 hours, according to the CEC-L-45-A-99 standard).

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

(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 the shear conditions in the engine, referred to as the Bosch-30 cycle test.

The SAE J 300 classification defines the viscosity grades of new engine oils, in particular by measuring their kinematic viscosities at 40 ^° C. and / or 100 ^° C. A motor oil is of grade 40 according to SAE J 300 if its kinematic viscosity at

100 ° C is from 12.5 to 16.3 cSt.

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.

Grade 40 engine oils, especially the more viscous ones (and preferably those with a viscosity of more than 15.0 cSt, preferably 15.5 cSt, or grade 50 are generally used in 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 40 and 50 motor oils, measured at 100 ° C., after the Bosch-30 cycle test, must be greater than 12.0 and 15.0 cSt, respectively.

The lubricants according to the present invention which can be used as motor lubricants have a kinematic viscosity at 100 ^° C. of greater than 12.0 cSt, preferably in the range of 12.0 to 15.0 cSt after the Bosch-30 cycles test according to the standard. CEC-L-14-A-93 for an oil starting from grade 40.

After this same test, these lubricants have a kinematic viscosity at 100 ^° C. which is greater than 15.0 cSt, preferably in the range of 15.0 to 20.0 cSt, for a starting oil of grade 50. We use oil "from grade 40", or "from grade 50", to designate an oil that satisfies the conditions defined by the classification SAE J 300 for grade 40, or grade 50, respectively, when it is new, that is to say before use, that is to say before having undergone any shear in the body of the vehicle in which it will be put into service or before having undergone shearing under standardized test conditions.

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 KRL 20 hours test.

The Applicant has determined, from the in-service oil monitoring test data, that a viscosity of a lubricant at 100 ° C. after 20 hours standardized KRL test is greater than 10.0 cSt, preferably in the range. ranging from 10.0 to 12.5 cSt, for a grade 40 starting oil was suitable for use in hot climate transmissions.

Similarly, a viscosity of a lubricant at 100 ° C after 20 hours normalized test KRL greater than 10.0 cSt and strictly less than 11.0 cSt, preferably less than or equal to 10.9 cSt, for a starting oil grade 50, suitable for use in gearboxes in hot climates 3. Conditions for use as hydraulic circuit 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 avoiding the problem of starting with new oil, especially at low temperature, the viscosity of the lubricant, measured at 40 ° C, should be less than 75 cSt for hot climates after KRL test according to CEC-L-45-A-99 whose duration is reduced from 20 hours to 3 hours, for an oil starting from grade 40 or 50.

Thus, the lubricant compositions according to the present invention are suitable for use in engines, transmissions, and hydraulic systems as they have a viscosity profile that satisfies the following cumulative conditions below. For an oil starting from grade 40:

(a ') at 100 ^° C., before shearing, the kinematic viscosity of the new lubricating composition is greater than 15.0 cSt, preferably 15.5 cSt, and less than 16.3 cSt, (a) at 100 ^° C. after the Bosch-30 cycles test according to CEC-L-14-A-93, the kinematic 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 starting from grade 40 _; (b) at 100 ° C after KRL -20 hours according to CEC-L-45-A-99 the viscosity of the lubricating composition is greater than 10.0, preferably in the range of 10.0 to 12 , 5, for an oil starting from grade 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 between 61 and 75; cSt, for an oil starting from grade 40.

For an oil starting from grade 50:

(a ') at 100 ° C, before shear, the kinematic viscosity of the new lubricant composition is greater than 16.3 cSt and less than 21.9 cSt,

(a) at 100 ^° C. after the Bosch-30 cycles test according to CEC-L-14-A-93, the kinematic viscosity of the final lubricating composition is greater than 15.0 cSt, preferably in the range from 0 to 20.0 cSt, for an oil starting from grade 50,

(b) at 100 ^° C. after KRL -20 hours test according to CEC-L-45-A-99 the viscosity of the lubricating composition is greater than 10.0 cSt and strictly less than 11.0 cSt, preferably lower than or equal to 10.9 cSt, for an oil starting from grade 50, 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 between 61 and 75; cSt, for an oil starting from grade 50. Under these conditions, these compositions are particularly adapted to hot climates.

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 above 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 II 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. In addition, the lubricants according to the present invention necessarily comprise at least one base oil selected from the group I to IL oils.

Preferably, the lubricants according to the present invention comprise at least

50%, preferably at least 70% by weight, of one or more base oils chosen from oils of groups I to II.

(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 the ACEA (Association of European Automobile Manufacturers) and / or the APL (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 (eg PIB-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 V.I. (Viscosity Index) of the 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 shearing: these are polymers whose PSSI after standardized test KRL 20 hours at 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 the hydraulics. In the group of polymers of type "A", there will be found in particular and not limited to viscosity improvers chosen from viscous polyalphaolefms (PAO) (viscosity at 100 ^° C. greater than 90 cSt), polyisobutenes (PIB), polymethacrylates (PMA). More specifically, type A polymers are viscosity improvers selected from polymethacrylates (Viscoplex 0-030, 0-110, 6-054, 8-220, 12-310), viscous polyalphaolefins (Spectrasyn 1000,300,150), polyisobutenes (Indopole 2100, Lubrizol 3174), polymeric esters (Kenjetlube 2700).

2) The group of polymers of type "B" comprises polymers which have a permanent index of shear stability (PSSI), measured after standardized test KRL 20 hours at 100 ⁰ C between 40 and 65 excluded terminals. 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" comprises the polymers which have a permanent index of shear stability (PSSI), measured after standardized test KRL 20 hours at 100 ° C greater than or equal to 65. These polymers are very sensitive to shearing: these are polymers whose PSSI after standardized test KRL 20 hours at 100 ⁰ C is greater than or equal to 65, preferably 65 to 100. This type of polymer will shear very quickly in hydraulics, with a subsequent drop in viscosity and durable lubricant in this body, thus avoiding low temperature starting problems.

In the group of "C" -type polymers, there are, in particular and without limitation, the viscosity-improving polymers chosen from the category of copolymeric 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 ° C.

This distinction is characterized by the existence of a PSSI difference of at least 25 between the PSSIs 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 relative to 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 lubricant 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 II 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 ° C in 1 liter flasks. ASTM D445 is used for the determination of kinematic viscosities. Two samples of lubricants were prepared, grade 40 and 30, respectively, according to the SAE J 300 classification.

Example 1

A lubricant containing 69.1% by weight of a Group I base oil having a viscosity of 3.53 cSt at 100 ° C was prepared and 15.4% by weight of a commercial additive package referenced in Ie 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:

13% by weight of a poly-olefin type "A" according to the present invention, having a PSSI of 35 and

2.5% by weight of a formulation containing about 9% 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 grade 40 according to SAE J300 classification. Its kinematic viscosity at 100 ^° C. before shear is 15.66 cSt

The following table gives the viscosity values at cSt of this lubricating composition: initial, at 100 ° C., before shearing at 100 ° C. after KRL -20 hours test according to CEC-L-45-A-99, at 100 ⁰ C after Bosch-30 cycles test according to the CEC-L-14-A-93 standard, 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.

Table I:

Spectrasyn 1000 is a PoIy alpha olefin (PAO)

SV 301 is a hydrogenated styrene-butadiene copolymer

The additive package is a commercial additive package for engine oil diluted in Group I oils not containing any type A, B or C polymer according to the present invention.

This package makes it possible in particular to formulate engine lubricants with performances at level E3 or higher of the ACEA.

Claims

1. A lubricating composition comprising at least one base oil groups of I to II, and a mixture of at least two polymers having a difference of permanent shear stability index (PSSI) ₅ measured after the standardized test KRL 20 hours at 100 ° C of at least 25, and having a viscosity profile such that: (a ') at 100 ° C, before shear, the kinematic viscosity of the new lubricant composition is greater than 15.0 cSt, preferably 15.5 cSt and less than 16.3 cSt, (a) at 100 ° C after Bosch test -30 cycles according to CEC-L-14-A-93, the kinematic viscosity of the final lubricating composition is greater than 12.0 cSt, preferably in the range of 12.0 to 15.0 cSt, for oil from grade 40, (b) at 100 ^° C. after the KRL -20 hours test according to CEC-L-45-A-99 the viscosity of the lubricating composition is greater than 10.0, preferably in the range of 10.0 to 12; , 5, for an oil starting from grade 40, and (c) at 40 ^° C. after the KRL-3 hours test, according to standard CEC-L-45-A-99, the test duration of which is reduced to 3 hours, the viscosity of the lubricating composition is between 61 and 75; cSt, for an oil starting from grade 40. 2. Lubricating composition comprising at least one Group I to II base oil, and a mixture of at least two polymers having a difference in Shear Stability Index (PSSI), measured after standardized test KRL 20 hours at 100 ⁰ C of at least 25, and having a viscosity profile such that: (a ') at 100 ^° C., before shearing, the kinematic viscosity of the new lubricant composition is greater than 16.3 cSt and less than 21.9 cSt, (a) at 100 ^° C. after the Bosch-30 cycles test according to CEC-L-14-A-93, the kinematic viscosity of the final lubricating composition is greater than 15.0 cSt, preferably in the range from , 0 to 20.0 cSt, for an oil starting from grade 50, (b) at 100 ° C after KRL -20 hours test according to CEC-L-45-A-99 the viscosity of the lubricating composition is higher at 10.0 cSt and strictly less than 11.0 cSt, preferably less than or equal to 10.9 cSt, for a starting oil of grade 50, 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 between 61 and 75; cSt, for an oil starting from grade 50. 3. Lubricating composition according to any one of claims 1 to 2 comprising at least 50% by weight relative to the weight of the final composition of one or more base oils including at least one oil selected from oils of groups I to II and at least 5%, preferably 5 to 40%, or even more 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 being differentiated from each other by their belonging to a distinct range of permanent shear stability index (PSSI) such that: 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 ° 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 ° C greater than or equal to 65; 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. 4. Lubricating composition according to any one of claims 1 to 3 comprising at least 50%, preferably at least 70% by weight of one or more base oils selected from Group I to IL oils. A lubricating composition according to any one of claims 3 to 4 wherein each of the polymers of the mixture is obtained from monomeric units of a distinct chemical nature. The lubricating composition according to any one of claims 3 to 5 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 membership in a distinct range of permanent shear stability index (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 or weight-average molecular mass, the mass distribution Molecular 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. 7. Lubricating composition according to any one of claims 3 to 6 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%. 8. Lubricating composition according to any one of claims 3 to 7 wherein the mixture comprises two polymers, one type A and the other type C. 9. Lubricating composition according to claim 8 wherein the ratio by weight of the mixture of the two polymers A / C ranges from 10/90 to 90/10. 10. Lubricating composition according to any one of claims 3 to 9 further comprising from 5 to 30% by weight based on the weight of the final composition of a functional additive package and optionally less than 1% by weight, preferably from 0.2% to 0.5% by weight weight relative to the weight of the final composition of a pour point improver. 11. Lubricating composition according to any one of claims 3 to Wherein the polymers of the blend are selected from the viscosity improver type polymers and optionally from the pour point improver type polymers. 12. Lubricating composition according to claim 11 wherein the viscosity improving polymers chosen from poly-alpha-olefins (PAO) with a kinematic viscosity at 100 ° C. of greater than 90 cSt, polyisobutenes (PIB), polymeric esters, Olefins Copolymers (OCP), homopolymers or copolymers of styrene, butadiene or isoprene, polymethacrylates (PMA). The lubricating composition of claim 11 wherein the pour point improver polymers are selected from polymethacrylates (PMA). 14. Lubricating composition according to any one of claims 3 to 13 wherein the type A polymers are viscosity improving polymers selected from polymethacrylates, polyalphaolefins of kinematic viscosity at 100 ^° C. greater than 90 cSt, polyisobutenes, polymeric esters. 15. Lubricating composition according to any one of claims 3 to 13 wherein the type C polymers are viscosity improving polymers selected from polymethacrylates, olefin-Co-Polymers, hydrogenated styrene-isoprene copolymers, copolymer esters. 16. Lubricating composition according to any one of claims 3 to Wherein the B-type polymers are polymethacrylate viscosity enhancing polymers. 17. Lubricating composition according to any one of claims 3 to 16 having the characteristics defined in claim 1 or 2. 18. A method of manufacturing a lubricant composition according to one of claims 1 to 17 wherein is incorporated a mixture comprising at least two different polymers in at least one group I to II oil optionally comprising an additive package and optionally a pour point improver. 19. The manufacturing method according to claim 18 of a lubricating composition according to any one of claims 1 to 17 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. 20. The manufacturing method according to claim 18 of a lubricating composition according to any one of claims 1 to 17 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. 21. The manufacturing method according to claim 18 of a lubricant composition according to one of claims 1 to 17 wherein 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 thinner. package of additives. 22. Use of a lubricant composition according to any one of claims 1 to 17 as a single fluid for lubricating various bodies of self-propelled vehicles. 23. Use according to claim 22 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. 24. Use according to claim 22 or 23 wherein the single fluid is also used to lubricate the brake control circuit, the onboard compressor and possibly other secondary organs.