EP3990592A1

EP3990592A1 - Use of a triazole compound as an additive for improving the anti-corrosion properties of a lubricant composition for a propulsion system of an electric or hybrid vehicle

Info

Publication number: EP3990592A1
Application number: EP20736271.6A
Authority: EP
Inventors: Shimin Zhang; Hakim EL-BAHI; Julien Guérin
Original assignee: Total Marketing Services SA
Current assignee: TotalEnergies Onetech SAS
Priority date: 2019-06-28
Filing date: 2020-06-25
Publication date: 2022-05-04
Also published as: US20220364011A1; WO2020260457A1; US12043814B2; CN114555762B; KR20220032564A; MX2021015547A; FR3097871B1; FR3097871A1; JP2022538639A; CN114555762A

Abstract

. The invention relates to the use of at least one triazole compound as an additive for improving the anti-corrosion properties of a lubricant composition for a propulsion system of an electric or hybrid vehicle, said lubricant composition comprising one or more amino and/or sulfur anti-wear additives. The invention also relates to the use of a lubricant composition for lubricating a propulsion system of an electric or hybrid vehicle.

Description

Title: USE OF A TRIAZOLE-TYPE COMPOUND AS AN ADDITIVE TO IMPROVE THE ANTI-CORROSION PROPERTIES OF A LUBRICANT COMPOSITION INTENDED FOR A PROPULSION SYSTEM OF AN ELECTRIC OR HYBRID VEHICLE.

The present invention relates to the field of lubricating compositions for a propulsion system of an electric or hybrid vehicle. It relates more particularly to the use of compounds of triazole type, as additives for improving the anti-corrosion properties of a lubricating composition incorporating one or more anti-wear additive (s) amine (s) and / or sulfur (s). .

Technical area

The evolution of international standards for the reduction of CO ₂ emissions, but also for the reduction of energy consumption, pushes car manufacturers to offer alternative solutions to combustion engines.

One of the solutions identified by car manufacturers is to replace combustion engines with electric motors. Research into reducing CO ₂ emissions has therefore led to the development of electric vehicles by a number of automobile companies.

For the purposes of the present invention, the term “electric vehicle” is intended to denote a vehicle comprising an electric motor as the sole means of propulsion, unlike a hybrid vehicle which comprises a combustion engine and an electric motor as combined propulsion means. .

By "propulsion system" within the meaning of the present invention, is meant a system comprising the mechanical parts necessary for the propulsion of an electric vehicle. The propulsion system thus more particularly includes an electric motor, comprising the rotor-stator assembly of the power electronics (dedicated to speed regulation), a transmission and a battery.

In general, it is necessary to use, in electric or hydride vehicles, lubricating compositions, also called “lubricants”, for the main purposes of reducing the frictional forces between the various parts of the system. propulsion of the vehicle, especially between moving metal parts in engines. These lubricating compositions are also effective in preventing premature wear or even damage to these parts, and in particular to their surface.

To do this, a lubricating composition is conventionally composed of one or more base oil (s), which are generally associated with several additives dedicated to stimulating the lubricating performance of the base oil, such as, for example, friction modifying additives, but also to provide additional performance.

In particular, so-called "anti-wear" additives are considered in order to reduce the wear of parts of the propulsion system, in particular of the mechanical parts of the engine, and thus to prevent degradation of the durability of the engine.

There is a wide variety of anti-wear additives, among which there may be mentioned, for example, dimercaptothiadiazoles, polysulfides, in particular sulfur-containing olefins, amine phosphates, or else phospho-sulfur additives, such as metal alkylthiophosphates, in in particular zinc alkylthiophosphates, and more specifically zinc dialkyldithiophosphates or ZnDTP.

Among these antiwear additives, preference is given in particular to amine and / or sulfur antiwear agents, such as dimercaptothiadiazoles, zinc dithiophosphate or polysulphides.

Unfortunately, these amino and / or sulfur antiwear additives, such as dimercaptothiadiazoles, have the disadvantage of being corrosive. The corrosion problem is particularly critical in electric propulsion systems. In particular, corrosion can lead to a risk of damage to the stator and rotor windings, sensors in the propulsion system, solenoid valves in the hydraulic system, but also bearings located between the rotor and the stator of a motor. electric, generally copper-based, and therefore particularly sensitive to corrosion, or even seals or varnishes present in the propulsion system.

In addition, to be able to cool the propulsion systems of electric or hybrid vehicles, it is imperative that the lubricant is insulating in order to avoid any failure in the electrical components. In particular, a conductive lubricant can lead to a risk of electric current leakage from the stator and rotor windings, thus reducing the efficiency of the propulsion systems, and creating a possible overheating at the level of the electrical components, even up to 'damage the system. It is therefore crucial, in within the framework of the implementation of lubricants for power systems of electric or hybrid vehicles, that the lubricants have good “electrical” properties in addition to non-corrosive properties.

The present invention aims precisely to overcome this drawback.

Summary of the invention

More specifically, the present invention relates to the use of at least one compound of triazole type, as an additive for improving the anti-corrosion properties of a lubricating composition, intended for a propulsion system of an electric or hybrid vehicle. and comprising one or more anti-wear additive (s) amine (s) and / or sulfur (s).

Compounds of triazole type, for example triazoles, in particular 1,2,3-triazole and their derivatives or else benzotriazole and its derivatives, are already known for their corrosion inhibiting properties, as described for example in the document

EP 1,159,380.

To the knowledge of the inventors, however, it has never been proposed to use compounds of the triazole type, together with one or more amine and / or sulfur anti-wear additives, in the context of the use of a lubricant. for a propulsion system of an electric or hybrid vehicle, to simultaneously improve the anti-wear properties and the anti-corrosion properties.

Surprisingly, as illustrated in the example which follows, the inventors have observed that the addition according to the invention of a compound of triazole type, in a lubricating composition dedicated to a propulsion system of an electric or hybrid vehicle , together with an amine and / or sulfur anti-wear additive, such as a dimercaptothiadiazole additive, makes it possible to effectively inhibit corrosion, unlike in particular other additives, however known as anti-corrosion additives, such as esters of organic acid, N-acyl sarcosines, for example N-oleoyl-sarcosine or else imidazoline derivatives.

Thus, the specific combination of at least one compound of triazole type and of at least one amino and / or sulfur anti-wear additive makes it possible to reduce, or even avoid, the phenomenon of corrosion induced in particular by the presence in of the lubricating composition of said additive (s) anti-wear amine (s) and / or sulfur (s).

For the purposes of the present invention, the term “anti-corrosion additive” is intended to denote an additive making it possible to prevent or reduce the corrosion of metal parts. An anti- corrosion thus makes it possible to confer good “anti-corrosion properties” on a composition containing it.

The use of one or more compound (s) of triazole type according to the invention, together with one or more amino and / or sulfur anti-wear additives advantageously makes it possible to access a lubricating composition jointly exhibiting good anti-wear performance. wear, while overcoming the corrosion problems discussed above. A composition according to the invention thus exhibits both good anti-wear and anti-corrosion properties.

The corrosive (or corroding) power of a compound can be evaluated according to a test implementing the study of the variation in the value of the electrical resistance of a copper wire of a predetermined diameter, as a function of the duration immersing this yarn in a composition comprising, in a non-corrosive medium, for example in one or more base oils, said compound to be tested. The variation in the value of this electrical resistance is correlated directly with the variation in the diameter of the wire tested. Thus, in the context of the present invention, a compound is qualified as “non-corrosive” when the loss in diameter of the copper wire studied is less than or equal to 0.5 mm after immersion for 80 hours, in particular less than or equal to. at 0.2 mm after immersion for 20 hours in the composition comprising said compound.

The dielectric properties of a lubricant are represented in particular by the electrical resistivity and the dielectric loss (tan d), and they can be measured according to standard IEC 60247.

Electrical resistivity represents the material's ability to oppose the flow of electric current. It is expressed in ohm-meter (W.ih). The resistivity should not be low to avoid electrical conduction.

The electrical dissipation factor or the tangent of the loss angle. The loss angle d is the complementary angle of the phase shift between the applied voltage and the alternating current. This factor reflects the energy losses by the Joule effect. The temperature rises are therefore directly linked to the value of d. Transmission oil typically has a tan value of on the order of one at room temperature. A good insulating lubricant should maintain a low level of tan d.

Advantageously, the compound of triazole type used according to the invention is chosen from triazoles, in particular 1,2,3-triazole, optionally substituted; the benzotriazoles and their derivatives, in particular tolyltriazole (also called tolutriazole) and its derivatives, and tetrahydrobenzotriazoles and their derivatives; and their mixtures.

Preferably, the triazole type compound is a benzotriazole or one of its derivatives, preferably a benzotriazole derivative, more preferably a tolyltriazole derivative. The introduction, into a lubricating composition intended for a propulsion system of an electric or hybrid vehicle, of one or more compound (s) of triazole type according to the invention thus advantageously allows the implementation, in the composition, additive (s) anti-wear amine (s) and / or sulfur (s), such as dimercaptothiadiazoles, without causing an undesirable corrosive effect.

Amino and / or sulfur anti-wear additives used in a lubricating composition according to the invention are more particularly detailed in the remainder of the text. They are preferably chosen from amino and sulfur antiwear additives. They may preferably be compounds of the thia (di) azoles type, in particular dimercaptothiadiazole derivatives. Also, a composition suitable for the invention has the advantage of being easy to formulate. In addition to good anti-wear and anti-corrosion performance, it has good stability, in particular to oxidation, as well as good properties in terms of electrical insulation.

The present invention also relates to G use, for lubricating a propulsion system of an electric or hybrid vehicle, in particular for lubricating the electric motor and the power electronics of an electric or hybrid vehicle, of a lubricating composition comprising :

- one or more anti-corrosion additives of the triazole type as defined in the invention; and

- one or more anti-wear amine and / or sulfur additives as defined in the invention. The present invention also relates to a method of lubricating a propulsion system of an electric or hybrid vehicle, comprising at least one step of bringing at least one mechanical part of said system into contact with a lubricating composition comprising at least an additive of triazole type as defined in the invention and at least one amine and / or sulfur anti-wear additive as defined in the invention.

Advantageously, a lubricating composition according to the invention is used to lubricate the electric motor itself, in particular the bearings located between the rotor and the stator of an electric motor, and / or the transmission, in particular the reduction gear, in an electric or hybrid vehicle. Other characteristics, variants and advantages of the use of the compounds of triazole type according to the invention will emerge more clearly on reading the description and the examples which follow, given by way of illustration and not by way of limitation of the invention.

In the remainder of the text, the expressions "between ... and ...", "ranging from ... to ..." and "varying from ... to ..." are equivalent and are intended to mean that the terminals are included, unless otherwise stated.

Brief description of the drawings

[Fig 1] schematically represents an electric or hybrid vehicle propulsion system.

detailed description

TRIAZOLE ADDITIVES

As specified above, the additive used as an anti-corrosion agent according to the invention, together with one or more anti-wear amine and / or sulfur additives, in a lubricating composition for a vehicle engine system electric or hybrid, is a triazole type compound.

Compounds of the triazole type are already known for their anti-corrosion properties. However, as indicated above, such compounds have never been proposed, together with the use of one or more anti-wear amine and / or sulfur additives, in a lubricating composition intended for a propulsion system of a. electric or hybrid vehicle.

Triazole compounds are mono or polycyclic compounds comprising at least one 5-membered ring incorporating three nitrogen atoms.

The compounds of triazole type are more particularly chosen from triazoles and their derivatives.

The triazoles, of general formula C2H3N3, can exist in the following forms, respectively 1H-1,2,3-triazole, 2H-1,2, 3 -triazole, 1H-1,2,4-triazole and 4H-1, 2,4-triazole: [Chem 1]

Benzotriazole-type compounds are specific triazole derivatives comprising a triazole ring coupled to a benzene ring, as shown below:

[Chem 2]

The triazole compound used according to the invention is preferably chosen from triazoles, in particular 1,2,3-triazole, optionally substituted; benzotriazoles and their derivatives, in particular tolyltriazole and its derivatives and tetrahydrobenzotriazoles and their derivatives; and their mixtures.

Thus, the compound of triazole type can be chosen from triazoles, in particular 1,2,3-triazole, optionally substituted; benzotriazoles and their derivatives; and mixtures thereof, preferably is a benzotriazole derivative, more preferably a tolyltriazole derivative.

As substituted triazoles, there may be mentioned in particular 1,2,3-triazoles substituted with one or more groups chosen from alkyl, aryl amine and acyl groups. According to a particular embodiment, the additive of triazole type used according to the invention can be chosen from 1,2,3-triazole and its derivatives, corresponding to the following formula (I): [Chem 3]

in which R, R 'and R ”are chosen, independently of each other, from hydrogen, an alkyl group, preferably C ₁ to C ₂₄ , an amine group such as a group -NR ¹ R ² , a acyl group such as a -COR ³ group, or an aryl group such as a phenyl or tolyl group; with R ¹ , R ² and R ³ being chosen, independently of one another, from a hydrogen atom or a C ₁ to C ₂₄ , preferably C ₂ to C ₁₈ alkyl group

As benzotriazole derivatives, there may be mentioned in particular the benzotriazoles substituted with one or more groups chosen for example from alkyl groups, such as for example tolutriazole (also called tolyltriazole), 1 ethyl lbenzotriazole, I 'hexy lbenzotriazole, 1 'octyl benzotriazole, etc., alkyl groups substituted by one or more amine functions, aryl groups, such as for example a phenolbenzotriazole, alkylaryl or arylalkyl groups, or other substituents such as hydroxy, alkoxy, halogen groups, etc.

According to a particularly preferred embodiment, the additive of triazole type used according to the invention can be chosen from benzotriazole and its derivatives, in particular corresponding to the following formula (II):

[Chem 4]

in which R and R 'are chosen, independently of one another from a hydrogen atom, a C ₁ to C ₂₄ alkyl group, optionally substituted by one or more groups -NR ⁴ R ⁵ ; an -NR ¹ R ^{2 group} ; an acyl group of -COR ³ type and a aryl group such as a phenyl or tolyl group;

with R ¹ , R ² and R ³ being chosen, independently of each other, from a hydrogen atom or a C ₁ to C ₂₄ , preferably C ₂ to C ₁₈ alkyl group;

and R ⁴ and R ⁵ representing, independently of one another, a hydrogen atom, a linear or branched, preferably branched, C3 to C14, preferably alkyl group.

C ₆ to C ₁₂ .

Preferably, the triazole compound is tolyltriazole or a derivative thereof.

Preferably, the compound of triazole type is a tolyltriazole derivative of the following formula (IIa):

[Chem 5]

in which R ⁴ and R ⁵ are, independently of one another, as defined above for formula (II); and

-A- represents an alkylene group, linear or branched, preferably linear, C ₁ to C ₆ , preferably C ₁ to C ₃ and more preferably a methylene group (-CH ₂ -), in particular, said derivative of tolyltriazole being 2-ethyl-N- (2-ethylhexyl) -N - [(4-methylbenzotriazol-1-yl) methyl] hexan-1-amine.

According to a particular embodiment, the compound of triazole type is of formula (Ha), in which R ⁴ and R ⁵ represent branched C 1 to C ₁₂ alkyl groups and -A- represents a C ₁ to C ₃ alkylene group , preferably a methylene group.

In the context of the present invention, and unless otherwise indicated, the definitions below apply:

A halogen represents an atom selected from fluorine, chlorine, bromine or iodine.

An alkyl group represents a linear or branched hydrocarbon chain. For example, a C _x -C _z alkyl group represents a linear or branched hydrocarbon chain comprising from x to z carbon atoms.

An alkylene group, a divalent, linear or branched alkyl group. For example a group C _x -C _z alkylene represents a divalent hydrocarbon chain of x to z carbon atoms, linear or branched.

An aikoxy group represents an —O-alkyl radical, in which the alkyl group is as defined above.

An aryl group represents an aromatic mono- or polycyclic group, in particular comprising between 6 and 10 carbon atoms. By way of example of an aryl group, mention may be made of phenyl or naphthyl groups.

Preferably, the triazole type compound is a benzotriazole or one of its derivatives, preferably a benzotriazole derivative, more preferably a tolyltriazole derivative.

The triazole-type compounds required according to the invention can be commercially available, or else prepared according to synthetic methods known to those skilled in the art.

The invention is not limited to the triazole-type compounds specifically described above. Other compounds of the triazole type, in particular derivatives of triazole or of benzotriazole, in particular derivatives of tolyltriazole, can be used as anti-corrosion additives according to the invention.

It is understood in the context of the present invention that a compound of triazole type can be in the form of a mixture of at least two compounds of triazole type, in particular as defined above.

The compound (s) of triazole type, in particular as defined above, can be used in a lubricating composition according to the invention, in an amount of 0.01 to 5% by weight, in particular from 0.1 to 3% by mass, and more particularly from 0.5 to 2% by mass, relative to the total mass of the lubricating composition.

LUBRICANT COMPOSITION

Amino and / or sulfur anti-wear additives

As indicated above, a lubricating composition considered according to the invention comprises one or more anti-wear amine and / or sulfur additives.

The term “amine and / or sulfur anti-wear additive” is intended to denote an additive chosen from amine anti-wear additives, sulfur anti-wear additives and amine and sulfur anti-wear additives. The term “anti-wear additive” is intended to denote a compound which, used in a lubricating composition, in particular a lubricating composition for a propulsion system of an electric or hybrid vehicle, makes it possible to improve the anti-wear properties of the composition.

The amine and / or sulfur antiwear additive can for example be chosen from additives of the thia (di) azole type, in particular derivatives of dimercaptothiadiazole; polysulphide additives, in particular sulfur olefins; amine phosphates; phospho-sulfur additives such as alkylthiophosphates; and their mixtures.

Thia azoles additives.

According to a particularly preferred embodiment, a lubricating composition considered according to the invention comprises at least one anti-wear additive of the thia (di) azoles type. Thia (di) azole compounds are compounds that contain both a sulfur atom and at least one nitrogen atom in a five-atom ring. Benzothiazoles are a special type of thia (di) azoles. This term thia (di) azole includes, besides cyclic compounds containing one sulfur atom and one nitrogen atom per five atom ring, also thiadiazoles which contain sulfur and two nitrogen atoms in such a ring.

In particular, the thia (di) azole type compounds can be chosen from benzothiazole derivatives, thiazole derivatives and thiadiazole derivatives.

Preferably, the antiwear additive can be a thiadiazole derivative.

Thiadiazoles are heterocyclic compounds comprising two nitrogen atoms, one sulfur atom, two carbon atoms and two double bonds, of general formula C2N2SH2, which may exist in the following forms, respectively: 1,2,3-thiadiazole; 1,2,4-thiadiazole; 1,2,5-thiadiazole; 1,3,4-thiadiazole:

[Chem 6]

1, 2, 3 -thiadiazole 1, 2, 4 -thiadiazole

1, 2, 5 -thiadiazole 1, 3, 4 -thiadiazole

Preferably, the thiadiazole derivative is a derivative of dimercaptothiadiazole.

Thus, according to a particularly preferred embodiment, a lubricating composition according to the invention comprises at least one anti-wear additive chosen from derivatives of dimercaptothiazole.

The term “dimercaptothiadiazole derivative according to the invention” means chemical compounds derived from the following four dimercaptothiadiazole molecules, below: 4,5-dimercapto 1,2,3-thiadiazole, 3,5-dimercapto-1,2,4 -thiadiazole, 3,4-dimercapto-l, 2,5-thiadiazole, 2,5-dimercapto-l, 3,4-thiadiazole, taken alone or as a mixture:

[Chem 7]

4, 5-dimercapto - 1, 2, 3 -thiadiazole 3, 5-dimercapto-1, 2, 4 -thiadiazole

3, 4-dImercapto - 1, 2, 5 -thia diazole 2, 5-dimercapto-1. 3, 4 -diia diazole

The dimercaptothiadiazole derivatives are more particularly molecules or mixture of molecules based on 4, 5-dimercapto-1, 2, 3 -thiadiazole, 3, 5-dimercapto-1, 2, 4-thiadiazole, 3,4-dimercapto-1,2,5-thiadiazole or 2,5-dimercapto-1,3,4-thiadiazole, as shown above, in which at least one of the substitutions = S, or even both substitutions = S on the thiadiazole ring is replaced by a substituent:

[Chem 8]

wherein * represents the bond with a carbon atom of the 5-membered ring; n represents an integer equal to 1, 2, 3 or 4; and R 1 is chosen from a hydrogen atom, a linear or branched, saturated or unsaturated alkyl group comprising from 1 to 24 carbon atoms, preferably from 2 to 18, more preferably from 4 to 16, even more preferably from 8 to 12 or an aromatic substituent.

In particular, taking 2,5-dimercapto-1,3,4-thiadiazole as an example, the 2,5-dimercapto-1,3,4-thiadiazole derivatives are molecules of the following formulas taken alone or as a mixture:

[Chem 9]

[Chem 10]

in which the group or groups R ₁ represent, independently of one another, hydrogen atoms, linear or branched alkyl or alkenyl groups, comprising from 1 to 24 carbon atoms, preferably from 2 to 18, more preferably from 4 to 16, again more preferably from 8 to 12 or aromatic substituents, n being, independently of one another, integers equal to 1, 2, 3 or 4, preferably n being equal to 1.

Preferably, R 1 represent, independently of one another, linear alkyl groups, C ₁ to C ₂₄ , preferably C ₂ to C ₁₈ , in particular C ₄ to C _16, more particularly C ₈ to C ₁₂ and preferably C ₁₂ .

The dimercaptothiadiazole derivatives used in the present invention may be commercially available, for example from the suppliers Vanderbilt, Rhein Chemie or Afton.

The amine and / or sulfur antiwear additive or additives used in a lubricating composition according to the invention can still be chosen from among sulfurized antiwear additives of the poly sulfide type, in particular sulfur olefins.

The sulfur-containing olefins used in a lubricating composition according to the invention can in particular be dialkyl sulfides represented by the general formula R _a -S _x -R _b , where R _a and R _b are alkyl groups comprising from 3 to 15 carbon atoms. , preferably from 1 to 5 carbon atoms, preferentially 3 carbon atoms, and x is an integer between 2 and 6.

Preferably, the poly sulfide additive is chosen from dialkyl trisulfides.

Preferably, the anti-wear additive present in a composition used according to the invention is chosen from amino and sulfur anti-wear additives, and advantageously from thia (di) azole compounds as described above and more preferably among the derivatives of dimercaptothiadiazole.

A lubricating composition considered according to the invention can comprise from 0.01% to 5% by mass, in particular from 0.1% to 3% by mass and more particularly from 0.5% to 2% by mass of additive (s ) anti-wear amines and / or sulfur, preferably of thia (di) azole type and more preferably chosen from derivatives of dimercaptothiadiazole, relative to the total mass of the lubricating composition.

The use of other anti-wear additives, known in particular for lubricants for propulsion systems, distinct from amine and / or sulfur additives, can be envisaged, provided that they do not affect the properties conferred by the combination. of said compound of triazole type and of said amino and / or sulfur antiwear additive (s) according to the invention.

Preferably, a lubricant composition required according to the invention is free of antiwear additive other than said amine and / or sulfur antiwear additive (s) used according to the invention.

According to a particularly preferred embodiment, a lubricating composition considered according to the invention combines:

- one or more additives of triazole type chosen from benzotriazole derivatives, preferably tolyltriazole derivatives, and in particular those of formula (Ha) indicated above; and

- one or more amino and sulfur antiwear additives, preferably chosen from derivatives of dimercaptothiazole, in particular as defined above.

According to a particularly preferred embodiment, a lubricating composition considered according to the invention combines, as an amine and / or sulfur antiwear additive, a derivative of 2,5-dimercapto-l, 3,4-thiadiazole and, as a compound of triazole type, a tolyltriazole derivative, in particular 2-ethyl-N- (2-ethylhexyl) -N - [(4-methylbenzotriazol-1-yl) methyl] hexan-1-amine.

LUBRICANT COMPOSITION

A composition used according to the invention may comprise, in addition to one or more additives of triazole type and one or more anti-wear additives amine (s) and / or sulfur (s), in particular as defined above, one or more base oils, as well as other additives, conventionally considered in lubricating compositions.

Base oils

A lubricating composition considered according to the invention can thus comprise one or more base oils.

These base oils can be chosen from the base oils conventionally used in the field of lubricating oils, such as mineral, synthetic or natural, animal or vegetable oils or their mixtures.

It can be a mixture of several base oils, for example a mixture of two, three, or four base oils. In the remainder of the text, the name “fluid base” will denote the oil or the mixture of base oils of the lubricating composition considered according to the invention.

The base oils of the lubricating compositions considered according to the invention can in particular be oils of mineral or synthetic origins belonging to groups I to V according to the classes defined in the API classification (or their equivalents according to the ATIEL classification) and presented in Table 1 below or their mixtures.

[Table 1]

Mineral base oils include all types of base oils obtained by atmospheric and vacuum distillation of crude oil, followed by refining operations such as solvent extraction, dealphating, solvent dewaxing, hydrotreatment, hydrocracking, hydroisomerization and hydrofinishing. .

Mixtures of synthetic and mineral oils, which can be biobased, can also be used.

There is generally no limitation as to the use of different base oils to produce the compositions used according to the invention, except that they must have properties, in particular in terms of viscosity, d 'viscosity index, or resistance to oxidation, suitable for use in propulsion systems of an electric or hybrid vehicle.

The base oils of the compositions used according to the invention can also be chosen from synthetic oils, such as certain esters of carboxylic acids and alcohols, polyalphaolefins (PAO), and polyalkylene glycols (PAG) obtained by polymerization or copolymerization of alkylene oxides comprising from 2 to 8 carbon atoms, in particular from 2 to 4 carbon atoms.

The PAOs used as base oils are for example obtained from monomers comprising from 4 to 32 carbon atoms, for example from octene or decene. The weight average molecular weight of PAO can vary quite widely. Preferably, the weight average molecular mass of the PAO is less than 600 Da. The weight-average molecular mass of PAO can also range from 100 to 600 Da, from 150 to 600 Da, or even from 200 to 600 Da.

Advantageously, the oil or the base oils of the composition used according to the invention are chosen from polyalphaolefins (PAO), polyalkylene glycol (PAG) and esters of carboxylic acids and alcohols.

Preferably, the base oil (s) of the composition used according to the invention is (are) chosen from oils of group III, IV or V, and their mixtures, preferably is an oil of group III base.

According to an alternative embodiment, the oil or the base oils of the composition used according to the invention can be chosen from the base oils of group II.

It is up to the person skilled in the art to adjust the base oil content to be used in a composition suitable for the invention.

A lubricating composition considered according to the invention may comprise at least 50% by mass of base oil (s) relative to its total mass, in particular from 60% to 99% by mass of base oil (s).

Complementary additives

A lubricating composition suitable for the invention may also further comprise all types of additives, distinct from additives of the triazole type and anti-wear additives amine (s) and / or sulfur (s) defined in the context of the present invention. , suitable for use in a lubricant for a propulsion system of an electric or hybrid vehicle.

It is understood that the nature and quantity of additives used are chosen so as not to affect the properties in terms of anti-wear and anti-corrosion performance conferred by the combination of said compound (s) of triazole type and of said additive (s). amine (s) and / or sulfur (s) used according to the invention. Such additives, known to those skilled in the art in the field of lubricating and / or cooling the propulsion systems of electric or hybrid vehicles, can be chosen from friction modifiers, viscosity index modifiers, detergents, extreme pressure additives, dispersants, antioxidants, pour point depressants, defoamers and mixtures thereof.

Advantageously, a composition suitable for the invention comprises at least one additional additive chosen from antioxidants, detergents, dispersants, pour point depressant additives, anti-foam agents, and mixtures thereof.

These additives can be introduced individually and / or in the form of a mixture like those already available for sale for commercial lubricant formulations for vehicle engines, with a performance level as defined by ACEA ( Association of European Automobile Manufacturers) and / or API (American Petroleum Institute), well known to those skilled in the art.

A lubricating composition suitable for the invention may comprise at least one friction modifier additive. The friction modifier additive can be chosen from a compound providing metallic elements and an ash-free compound. Among the compounds providing metallic elements, mention may be made of transition metal complexes such as Mo, Sb, Sn, Fe, Cu, Zn, the ligands of which may be hydrocarbon compounds comprising oxygen, nitrogen or carbon atoms. sulfur or phosphorus. The ash-free friction modifying additives are generally of organic origin and can be chosen from fatty acid and polyol monoesters, alkoxylated amines, alkoxylated fatty amines, fatty epoxides, borate fatty epoxides; fatty amines or fatty acid glycerol esters. According to the invention, the fatty compounds comprise at least one hydrocarbon group comprising from 10 to 24 carbon atoms.

A lubricating composition suitable for the invention may comprise from 0.01 to 2% by weight or from 0.01 to 5% by weight, preferably from 0.1 to 1.5% by weight or from 0.1 to 2%. by weight of friction modifier additive, relative to the total weight of the composition.

A lubricating composition used according to the invention can comprise at least one antioxidant additive. The antioxidant additive generally makes it possible to delay the degradation of the composition in service. This degradation can be reflected in particular by the formation of deposits, by the presence of sludge or by an increase in the viscosity of the composition.

Antioxidant additives act in particular as radical inhibitors or destroyers of hydroperoxides. Among the antioxidant additives currently used, there may be mentioned antioxidant additives of phenolic type, antioxidant additives of amine type, phosphosulfurized antioxidant additives. Some of these antioxidant additives, for example phosphosulfurized antioxidant additives, can generate ash. The phenolic antioxidant additives can be ash-free or in the form of neutral or basic metal salts. The antioxidant additives can in particular be chosen from sterically hindered phenols, sterically hindered phenol esters and sterically hindered phenols comprising a thioether bridge, diphenylamines, diphenylamines substituted with at least one C ₁ - C ₁₂ alkyl group, N , N'-dialkyl-aryl-diamines and mixtures thereof.

Preferably according to the invention, the sterically hindered phenols are chosen from compounds comprising a phenol group of which at least one carbon vicinal of the carbon carrying the alcohol function is substituted by at least one C ₁ - C ₁₀ alkyl group, preferably one. C ₁ -C ₆ alkyl group, preferably a C ₄ alkyl group, preferably by the tert-butyl group.

Amino compounds are another class of antioxidant additives that can be used, optionally in combination with phenolic antioxidant additives. Examples of amino compounds are aromatic amines, for example aromatic amines of formula NR ⁴ R ⁵ R ⁶ in which R ⁴ represents an aliphatic group or an aromatic group, optionally substituted, R ⁵ represents an aromatic group, optionally substituted, R ⁶ represents a hydrogen atom, an alkyl group, an aryl group or a group of formula R ⁷ S (0) _z R ⁸ in which R ⁷ represents an alkylene group or an alkenylene group, R ⁸ represents an alkyl group, a alkenyl group or an aryl group and z represents 0, 1 or 2.

Sulfurized alkyl phenols or their alkali and alkaline earth metal salts can also be used as antioxidant additives.

Another class of antioxidant additives are copper compounds, for example copper thio- or dithio-phosphates, salts of copper and carboxylic acids, copper dithiocarbamates, sulphonates, phenates, acetylacetonates. Copper I and II salts, salts of succinic acid or anhydride can also be used. A lubricating composition used according to the invention can contain all types of antioxidant additives known to those skilled in the art.

Advantageously, a lubricating composition used according to the invention comprises at least one antioxidant additive free of ash.

A lubricating composition used according to the invention can comprise from 0.5 to 2% by weight of at least one antioxidant additive, relative to the total weight of the composition. According to a particular embodiment, a lubricating composition used according to the invention is free from an antioxidant additive of aromatic amine type or of sterically hindered phenol type.

A lubricating composition suitable for the invention can also include at least one detergent additive.

Detergent additives generally reduce the formation of deposits on the surface of metal parts by dissolving by-products of oxidation and combustion.

The detergent additives which can be used in a lubricating composition used according to the invention are generally known to those skilled in the art. The detergent additives can be anionic compounds comprising a long lipophilic hydrocarbon chain and a hydrophilic head. The associated cation can be a metallic cation of an alkali or alkaline earth metal.

The detergent additives are preferably chosen from alkali metal or alkaline earth metal salts of carboxylic acids, sulphonates, salicylates, naphthenates, as well as salts of phenates. The alkali metals and alkaline earth metals are preferably calcium, magnesium, sodium or barium.

These metal salts generally include the metal in a stoichiometric amount or else in excess, therefore in an amount greater than the stoichiometric amount. These are then overbased detergent additives; the excess metal providing the overbased character to the detergent additive is then generally in the form of a metal salt insoluble in oil, for example a carbonate, a hydroxide, an oxalate, an acetate, a glutamate, preferably a carbonate . A lubricating composition suitable for the invention may, for example, comprise from 2 to 4% by weight of detergent additive, relative to the total weight of the composition.

Also, a lubricating composition used according to the invention can comprise at least one dispersing agent.

The dispersing agent can be chosen from Mannich bases, succinimides and their derivatives.

A lubricating composition used according to the invention may for example comprise from 0.2 to 10% by weight of dispersing agent, relative to the total weight of the composition. According to a particular embodiment, a lubricating composition used according to the invention is free from dispersing agent of succinimide type.

A lubricating composition suitable for the invention may further comprise at least one antifoam agent.

The antifoam agent can be chosen from silicones.

A lubricating composition suitable for the invention may comprise from 0.01 to 2% by mass or from 0.01 to 5% by mass, preferably from 0.1 to 1.5% by mass or from 0.1 to 2% by mass of antifoaming agent, relative to the total weight of the composition.

A lubricating composition suitable for the invention may also include at least one pour point depressant additive (also called "PPD" agents for "For Point Depressant" in English).

By slowing the formation of paraffin crystals, pour point depressant additives generally improve the cold behavior of the composition. As examples of pour point lowering additives, there may be mentioned polymethacrylates, polyacrylates, polyarylamides, polyalkylphenols, polyalkylnaphthalenes, alkylated polystyrenes.

In particular, a lubricating composition used according to the invention may be free from dispersing agent of succinimide type and of antioxidant additive of aromatic amine type or of sterically hindered phenol type.

In terms of formulation of such a lubricating composition, said compound (s) of triazole type can be added to an oil or mixture of base oils, then the other additional additives, including the anti-wear additive (s). amino (s) and / or sulfur (s), added. Alternatively, said compound (s) of triazole type can be added to a pre-existing conventional lubricating formulation, comprising in particular one or more base oils, one or more anti-wear additives amine (s) and / or sulfur (s), and optionally additional additives.

Advantageously, a lubricating composition used according to the invention has a kinematic viscosity, measured at 100 ° C. according to the ASTM D445 standard, ranging from 1 to 15 mm ² / s. Advantageously, a lubricating composition used according to the invention has a kinematic viscosity, measured at 40 ° C. according to the ASTM D445 standard, ranging from 3 to 80 mm ² / s. According to an advantageous embodiment of the present invention, the values of electrical resistivity measured at 90 ° C. of the lubricating compositions used according to the invention are between 5 and 10,000 Mohm.m, more preferably between 6 and 5,000 Mohm. mr. According to an advantageous embodiment of the present invention, the dielectric loss values measured at 90 ° C. of the lubricating compositions used according to the invention are between 0.01 and 30, more preferably between 0.02 and 25, more preferably between 0.02 and 10.

Advantageously, a lubricating composition used according to the invention can be of a grade according to the SAEJ300 classification defined by formula (X) W (Y), in which X represents 0 or 5; and Y represents an integer ranging from 4 to 20, in particular ranging from 4 to 16 or from 4 to 12.

According to a particular embodiment, a lubricating composition used according to the invention comprises, or even consists of:

- a base oil or mixture of base oils, preferably chosen from polyalphaolefins (PAO), polyalkylene glycol (PAG) and esters of carboxylic acids and alcohols;

one or more anti-corrosion additives of the triazole type, preferably chosen from benzotriazole derivatives, in particular tolyltriazole derivatives, and more preferably those of formula (Ha) indicated above;

- one or more amino and / or sulfur antiwear additives, preferably one or more amino and sulfur antiwear additives, and more preferably chosen from compounds of thia (di) azoles type, in particular dimercaptothiazole derivatives such as defined above;

- optionally one or more additional additives chosen from antioxidants, detergents, dispersants, pour point depressant additives, defoamers, and mixtures thereof.

Preferably, a lubricating composition used according to the invention comprises, or even consists of:

- from 0.01% to 5% by mass, in particular from 0.1% to 3% by mass, and more particularly from 0.5% to 2% by mass, of one or more anti-corrosion additives of the triazole type, of preferably chosen from benzotriazole derivatives, in particular tolyltriazole derivatives, and more preferably those of formula (Ha) indicated above;

- from 0.01% to 5% by weight, in particular from 0.1% to 3% by weight, and more particularly from 0.5% to 2% by weight, of one or more anti-wear additives amine and / or sulfur , preferably one or more amino and sulfur anti-wear additives, and more preferably chosen from compounds of thia (di) azoles type, in particular dimercaptothiazole derivatives as defined above;

- from 60% to 99.9% by mass of base oil (s), preferably chosen from polyalphaolefins (PAO), polyalkylene glycols (PAG), esters of carboxylic acids and alcohols and their mixtures;

- optionally from 0.01% to 5% by mass of one or more additives chosen from antioxidants, detergents, dispersants, pour point lowering additives, anti-foam agents, and mixtures thereof;

the contents being expressed relative to the total mass of said lubricating composition.

APPLICATION

As indicated above, a lubricating composition suitable for the invention, as described above, is used as a lubricant for a propulsion system of an electric or hybrid vehicle, and more particularly of the engine and of the power electronics.

Thus, the present invention relates to the use of a lubricating composition as defined above, combining one or more anti-corrosion additives of triazole type, in particular as defined above, preferably derived from tolyltriazole, and one or more anti-wear additives. amines and / or sulfur, preferably derivatives of dimercaptothiazole, to lubricate a propulsion system of an electric vehicle or hybrid, in particular for lubricating the electric motor and the power electronics of an electric or hybrid vehicle.

As shown schematically in Figure 1, the propulsion system of an electric or hybrid vehicle, comprises in particular the electric motor part (1), an electric battery (2) and a transmission, and in particular a speed reducer (3).

The electric motor typically comprises power electronics (11) connected to a stator (13) and a rotor (14). The stator comprises coils, in particular copper coils, which are supplied alternately by an electric current. This makes it possible to generate a rotating magnetic field. The rotor itself consists of coils, permanent magnets or other magnetic materials, and is rotated by the rotating magnetic field.

A bearing (12) is generally integrated between the stator (13) and the rotor (14). A transmission, and in particular a speed reducer (3), makes it possible to reduce the speed of rotation at the output of the electric motor and to adapt the speed transmitted to the wheels, allowing at the same time to control the speed of the vehicle.

The bearing (12) is particularly subjected to high mechanical stresses and poses fatigue wear problems. It is therefore necessary to lubricate the bearing in order to increase its life. Also, the reducer is subjected to high friction stresses and therefore needs to be lubricated appropriately in order to prevent it from being damaged too quickly.

Thus, the invention relates in particular to the use of a composition as described above for lubricating an electric motor of an electric or hybrid vehicle, in particular for lubricating the bearings located between the rotor and the stator of an electric motor. .

It also relates to the use of a composition as described above to lubricate the transmission, in particular the reduction gear, in an electric or hybrid vehicle.

Advantageously, a composition according to the invention can thus be used to lubricate the various parts of a propulsion system of an electric or hybrid vehicle, in particular of the bearings located between the rotor and the stator of an electric motor and / or the transmission, in particular the reduction gear, in an electric or hybrid vehicle. Advantageously, as mentioned above, a lubricating composition according to the invention exhibits excellent anti-wear and anti-corrosion performance.

The invention also relates, according to another of its aspects, to a method of lubricating at least one part of a propulsion system of an electric or hybrid vehicle, in particular of the bearings located between the rotor and the stator of. an electric motor; and / or of the transmission, in particular of the reducer, comprising at least one step of bringing at least said part into contact with a composition as described above.

The present invention thus proposes a method for simultaneously reducing the wear and corrosion of at least one part of a propulsion system of an electric or hybrid vehicle, in particular of the bearings located between the rotor and the stator of an electric vehicle. electric motor; and / or of the transmission, in particular of the reducer, said method comprising at least one step of bringing at least said part into contact with a composition as described above.

All of the characteristics and preferences described for the composition used according to the invention as well as for its uses also apply to this process.

According to a particular embodiment, a composition according to the invention may exhibit, in addition to lubricating properties, good electrical insulation properties.

According to this embodiment, a composition according to the invention can simultaneously be used to lubricate one or more parts of a propulsion system of an electric or hybrid vehicle, in particular for lubricating the sensors and solenoid valves of the engine, bearings, but also the winding located at the rotor and stator of an electric motor, or the lubrication at the transmission level, in particular the gears, sensors, solenoid valves, or the reducer that we find in an electric or hybrid vehicle, and to electrically isolate at least one part of said propulsion system, in particular from the battery.

In the context of such an implementation variant, a lubricating composition considered according to the invention advantageously exhibits a kinematic viscosity, measured at 100 ° C according to the ASTM D445 standard, of between 2 and 8 mm ² / s, preferably between 3 and 7 mm ² / s. It is understood that the uses described above can be combined, a composition as described above can be used both as a lubricant, as an electrical insulator but also as a cooling fluid for the engine, the battery and the transmission of an electric or hybrid vehicle. According to the invention, the particular, advantageous or preferred characteristics of the composition according to the invention make it possible to define uses according to the invention which are also particular, advantageous or preferred.

The invention will now be described by means of the following examples, given of course by way of illustration and without limitation of the invention.

Example

Different compositions were evaluated:

- a C1 composition comprising an amine and sulfur anti-wear additive, of the dimercaptothiadiazole type and free of anti-corrosion additive;

- A composition C2 comprising said anti-wear additive of dimercaptothiadiazole type, and an anti-corrosion additive of triazole type, in accordance with the invention, of above-mentioned formula (Ha): 2-ethyl-N- (2-ethylhexyl) - N - [(4-methylbenzotriazol-1-yl) methyl] hexan-1-amine;

a C3 composition comprising said anti-wear additive of dimercaptothiadiazole type, and an anti-corrosion additive not in accordance with the invention, of alkylated organic acid ester type;

- A composition C4 comprising said anti-wear additive of dimercaptothiadiazole type, and an anti-corrosion additive not in accordance with the invention, of N-acyl sarcosine type (N-oleyl sarcosine); and

a composition C ₅ comprising said anti-wear additive of dimercaptothiadiazole type, and an anti-corrosion additive not in accordance with the invention, of imidazoline derivative type.

Compositions C ₁ to C ₅ comprise, in addition to the aforementioned compounds, a group III base oil.

The compositions and the amounts (expressed as a percentage by mass) are indicated in Table 2 below.

[Table 2]

Evaluation of anti-corrosion properties

Method of assessment

The corrosive (or corroding) power of a composition can be evaluated according to a test implementing the study of the variation in the value of the electrical resistance of a copper wire having a predetermined diameter, as a function of the duration d immersion of this thread within the composition. The variation in the value of this electrical resistance is correlated directly with the variation in the diameter of the wire tested. In the context of the present invention, the diameter of the wire chosen is 70mm.

In the present case, a copper wire is immersed in a test tube containing a volume of 20 mL of a composition to be tested (composition C2 being a composition according to the invention and compositions C 1 and C3 to C5 being compositions serving as comparisons). The resistance of the wire is measured using an ohmmeter.

The measurement current is 1mA.

The temperature of the composition to be tested is brought to 150 ° C.

The resistance of the copper wire is calculated by this equation (1):

[Math 1]

where R is the resistance, p is the resistivity of copper, L is the length of the wire, and S is the section area.

In this equation (1), p and L are constant. Thus, the resistance R is inversely proportional with the section area of the submerged wire.

The wire diameter is calculated from the section area (equation (2)):

[Math 2]

where D is the diameter of the wire.

We inject equation (2) into equation (1) to get the relationship between resistance and diameter (equation (3)):

[Math 3]

Thus, when the wire is corroded by the compositions to be tested, the diameter of the wire decreases, therefore causing an increase in the value of the resistance.

By monitoring the resistance, we are able to follow the change in the diameter of the wire, which is an image of the corrosion situation undergone by the submerged wire.

The wire diameter loss is therefore calculated directly from the measured resistance. When the measured resistance is infinite, it is an open circuit. So the wire broke, which defines very severe corrosion.

Results

The results are summarized in Table 3 below, and are expressed in mm (loss of diameter). The lower the value obtained, the better the anti-corrosion properties of the composition evaluated.

It is estimated that a composition is “non-corrosive” when the loss of diameter of the copper wire studied is less than or equal to 0.5 mm after immersion for 80 hours, in particular less than or equal to 0.1 mm after immersion. for 20 hours in the composition.

[Table 3]

It emerges from these results that the addition of a compound of triazole type in a lubricating composition further comprising at least one amine and / or sulfur anti-wear additive makes it possible to access significantly improved anti-corrosion properties compared to lubricating compositions free from compounds of triazole type or comprising anti-corrosion additives distinct from compounds of triazole type.

Claims

1. Use of at least one compound of triazole type, as an additive for improving the anti-corrosion properties of a lubricating composition, intended for a propulsion system of an electric or hybrid vehicle and comprising one or more additives (s) anti-wear amine (s) and / or sulfur (s).

2. Use according to claim 1, in which the compound of triazole type is chosen from triazoles, in particular 1,2,3-triazole, optionally substituted; benzotriazoles and their derivatives; and mixtures thereof, preferably is a benzotriazole derivative, more preferably a tolyltriazole derivative.

3. Use according to any one of the preceding claims, in which the triazole-type compound is a tolyltriazole derivative of the following formula (Ha):

in which :

R ⁴ and R ⁵ representing, independently of one another, a hydrogen atom, a linear or branched, preferably branched, C3 to C14, preferably C ₆ to C ₁₂ alkyl group; and

-A- represents an alkylene group, linear or branched, preferably linear, C ₁ to C ₆ , preferably C ₁ to C ₃ and more preferably a methylene group (-CH ₂ -); in particular said tolyltriazole derivative being 2-ethyl-N- (2-ethylhexyl) -N - [(4-methylbenzotriazol-1 -yl) methyl] hexan-1 -amine.

4. Use according to any one of the preceding claims, in which the amino and / or sulfur anti-wear additive is chosen from additives of thia (di) azole type, in particular derivatives of dimercaptothiadiazole; polysulphide additives, in particular sulfur-containing olefins; amine phosphates; phospho-sulfur additives such as alkylthiophosphates; and their mixtures.

5. Use according to any one of the preceding claims, wherein the amine and / or sulfur antiwear additive is selected from derivatives of

dimercaptothiadiazole, in particular 2,5-dimercapto-1,3,4-thiadiazole derivatives of the following formulas taken alone or as a mixture:

in which the group (s) R represents, independently of one another, hydrogen atoms, linear or branched alkyl or alkenyl groups, including

1 to 24 carbon atoms, preferably 2 to 18, more preferably 4 to 16, even more preferably 8 to 12 or aromatic substituents, n being, independently of one another, integers equal to 1, 2 , 3 or 4, preferably n being equal to 1.

6. Use according to any one of the preceding claims, in which the said compound (s) of triazole type is (are) present in a content ranging from 0.01 to 5% by mass, in particular from 0 , 1 to 3% by mass, and more particularly from 0.5 to

2% by mass, relative to the total mass of the lubricating composition; and / or said anti-wear additive (s) amine (s) and / or sulfur (s) is (are) present in a content ranging from 0.01 to 5% by mass, in particular from 0 , 1 to 3% by mass and more particularly from 0.5 to 2% by mass, relative to the total mass of the lubricating composition.

7. Use according to any one of the preceding claims, wherein said amine and / or sulfur antiwear additive is a derivative of 2,5-dimercapto-1,3,4-. thiadiazole and said triazole compound is a tolyltriazole derivative, in particular 2-ethyl-N- (2-ethylhexyl) -N - [(4-methylbenzotriazol-1-yl) methyl] hexan-1-amine.

8. Use of a lubricating composition comprising one or more anti-corrosion additives of the triazole type and one or more anti-wear additives amine and / or sulfur, for lubricating a propulsion system of an electric or hybrid vehicle, in particular for lubricating the electric motor and power electronics of an electric or hybrid vehicle.

9. Use according to the preceding claim, in which the anti-corrosion additive (s) of triazole type are as defined in any one of claims 2, 3, 6 and 7; and / or the amino and / or sulfur antiwear additive (s) are as defined according to any one of claims 4 to 7.

10. Use according to claim 8 or 9, for lubricating the bearings located between the rotor and the stator of an electric motor, and / or the transmission, in particular the reduction gear, of an electric or hybrid vehicle.