EP3990588A1

EP3990588A1 - Use of a sterically hindered aromatic amine or phenol compound as an anti-corrosion additive in a lubricant composition for a propulsion system of an electric or hybrid vehicle

Info

Publication number: EP3990588A1
Application number: EP20736272.4A
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
Anticipated expiration: 2040-06-25
Also published as: WO2020260460A1; US20220372392A1; KR20220032058A; FR3097870B1; CN114096647A; JP2022538640A; MX2021015550A; FR3097870A1; EP3990588B1

Abstract

. The invention relates to the use of at least one compound, which has at least one sterically hindered amine or phenolic function, as an anti-corrosion additive in 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 comprising one or more compounds, which has at least one sterically hindered amine or phenolic function, as one or more anti-corrosion additives, further comprising one or more amino and/or sulfur anti-wear additives, 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.

Description

Title: Use of an aromatic amine or sterically hindered phenol compound as an anticorrosion additive in a lubricating composition intended for a propulsion system of an electric or hybrid vehicle.

Technical area

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 exhibiting at least one sterically hindered amine or phenolic function, for improving the anti-corrosion properties of a lubricating composition incorporating one or more anti-wear additive (s) amine (s) and / or sulfur. (s).

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, or 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 propulsion system. 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 the mechanical parts of the engine, and thus prevent a 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.

The present invention aims precisely to overcome this drawback.

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 is aimed precisely at obtaining such properties.

Summary of the invention

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

Compounds exhibiting at least one sterically hindered amine or phenolic function, in particular exhibiting a single sterically hindered amine or phenolic function, are referred to, in the remainder of the text, under the name "compounds with sterically hindered amine or phenolic function".

Compounds with a sterically hindered amine or phenolic function, such as for example aromatic amines or hindered phenols, in particular alkylphenols, are already described for their function as anti-oxidants, for example in lubricants for engines, as described. for example in application WO 2006/064138. These antioxidants generally make 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. Antioxidants are able to scavenge free radicals formed during use of the lubricant, thereby interrupting chain reactions that may lead to the build-up of acids.

To the knowledge of the inventors, however, it has never been proposed to use these compounds, as anti-corrosion additives, in the context of the use of a lubricant for a propulsion system of a vehicle. electric or hybrid, to mitigate the corrosion effects generated by the use of anti-wear additive (s) amine (s) and / or sulfur (s). Surprisingly, as illustrated in the example which follows, the inventors have observed that such additives with a sterically hindered amine or phenolic function, for example of the diarylamine type, make it possible to effectively reduce the effects of corrosion induced by amine and / or sulfur anti-wear additives.

Thus, the addition of at least one compound with a sterically hindered amine or phenolic function, in particular of aromatic amine or alkylphenol type, advantageously makes it possible to improve the anti-corrosion properties of a lubricant comprising one or more 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 additive used in a composition thus makes it possible to improve the so-called "anti-corrosion" properties of this composition.

The use of one or more compound (s) with a sterically hindered amine or phenolic function according to the invention, together with one or more anti-wear amine and / or sulfur additives advantageously makes it possible to access a lubricating composition jointly exhibiting good anti-wear performance, 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 studying the variation in the value of the electrical resistance of a copper wire of a predetermined diameter, depending on the duration of immersion of this wire. within 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 2 μm after immersion for 80 hours, in particular less than or equal to 0 , 3 µm 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 can also be used to measure the properties of a lubricant. 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. A transmission oil typically has a tan d value of the order of unity at room temperature. A good insulating lubricant should maintain a low level of tan d.

Advantageously, the compound with a sterically hindered amine or phenolic function according to the invention used according to the invention is chosen from aromatic amines, in particular compounds of diarylamine type and more particularly of diphenylamine type; sterically hindered phenols, in particular alkylphenols; and their mixtures.

According to a preferred embodiment, the compound containing a sterically hindered amine or phenolic function is chosen from substituted diphenylamines, in particular substituted on at least one of the positions in para of the amine function, by at least one alkyl or alkenyl group, comprising from 1 to 12 carbon atoms, preferably from 3 to 10 carbon atoms.

For example, it may be p, p-butyl-octyl-diphenylamine.

According to another preferred embodiment, the compound with a sterically hindered amine or phenolic function is chosen from compounds comprising a phenol group of which at least one vicinal carbon of the carbon carrying the alcohol function is substituted by at least one group chosen from an alkyl group. optionally substituted Ci-Cio and a hydroxyl function.

For example, it may be octyl-3,5-di-tert-butyl-4-hydroxy-hydrocinnamate or 2,6-di-tert-butylphenol.

The introduction, into a lubricating composition intended for a propulsion system of an electric or hybrid vehicle, of one or more compound (s) with a sterically hindered amine or phenolic function 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.

The amine and / or sulfur antiwear additives used in a lubricating composition according to the invention are more particularly detailed in the remainder of the text. They are chosen preferably from amino and sulfur antiwear additives. They may preferably be compounds of the thia (di) azole type, in particular dimercaptothiadiazole derivatives. Also, a composition suitable for the invention has the advantage of being easy to formulate. It has, in addition to good anti-wear and anti-corrosion performance, 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 including:

- One or more compounds comprising at least one sterically hindered amine or phenolic function as defined in the invention, as anti-corrosion additive (s); and

- one or more anti-wear additive (s) amine (s) and / or sulfur (s) 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 a compound with a sterically hindered amine or phenolic function as defined in the invention, as an anti-corrosion additive and at least one anti-wear amine and / or sulfur 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 compounds with a sterically hindered amine or phenolic function as anti-corrosion additives according to the invention will become more apparent on reading the description and the examples which follow, given by way of illustration and without 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

ANTI-CORROSION ADDITIVES WITH AMINE OR PHENOLIOUE FUNCTION

CLOUDY STERIOUEMENT

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 compound having at least one sterically hindered amine or phenolic function.

As mentioned above, compounds with a sterically hindered amine or phenolic function, and more particularly of aromatic amine and hindered phenol type, are known to those skilled in the art, in the field of lubricants, for their antioxidant action. These compounds are able to act as radical inhibitors.

The term “sterically hindered” function is understood to mean that the function is hindered by steric effect or constraint. This bulkiness has the particular effect of making the amine or phenolic function significantly less nucleophilic than the unhindered amine or phenolic function, and thus of preventing nucleophilic addition reactions.

Such compounds have for example been described in applications WO 2006/064138, WO 2011/073960, etc.

However, as indicated above, such compounds have never been proposed as anti-corrosion additives in a lubricant for a motorization system of an electric or hybrid vehicle, for the purposes of reducing, or even inhibiting, the corrosion effects induced by the use of one or more anti-wear amine and / or sulfur additives.

The compounds with a hindered amine function can be more particularly chosen from aromatic amines, in particular as defined in the remainder of the text.

The compounds with a hindered phenolic function are preferably chosen from sterically hindered phenols, in particular alkylphenols, in particular as defined in the remainder of the text. Thus, according to a particular embodiment, the said compound or compounds with a hindered amine or phenolic function are chosen from aromatic amines, sterically hindered phenols, and mixtures thereof.

In particular, the compounds of aromatic amine type can be of formula:

[Chem 1]

R3R4R5N

in which R3 and R4 represent, independently of one another, a hydrogen atom, a C1-20, preferably C4-16 aliphatic group, or a substituted aromatic or heteroaromatic, monocyclic or polycyclic group, substituted or not substituted; R5 is an aromatic or heteroaromatic, monocyl or polycyclic condensed group, unsubstituted or carrying at least one C1 -20 alkyl substituent; or

R3 and R5 together form an aromatic or heteroaromatic, monocyclic or condensed polycyclic group.

The aromatic amines can be more particularly chosen from substituted or unsubstituted diphenylamines, substituted or unsubstituted phenylnaphthylamines, substituted or unsubstituted phenothiazines, substituted or unsubstituted imidodibenzyles, substituted or unsubstituted N, N'diphenyl (phenylenediamines) , and their mixtures.

According to a particularly preferred embodiment, the compounds with a hindered amine function are chosen from secondary amines in which the nitrogen atom is linked to at least one aryl group, preferably to at least one phenyl group.

Preferably, the compound with a hindered amine function is chosen from compounds of diarylamine type, in particular of which at least one of the aryl groups is a phenyl, and more particularly compounds of the diphenylamine type.

Thus, according to a particular embodiment, the compound with a hindered amine function is a compound of aromatic amine type chosen from diarylamines, preferably corresponding to the formula:

[Chem 2]

R ₆ -NH-R ₇

in which R ₆ and R7 are chosen, independently of one another, from:

- a phenyl group, optionally substituted, preferably in para of the function amine, by hydrocarbon groups, in particular chosen from alkyl or alkenyl groups, comprising from 1 to 12 carbon atoms, preferably from 3 to 10 carbon atoms; and

- a naphthyl group, optionally substituted, preferably at the para of the amine function, by hydrocarbon groups, in particular chosen from alkyl or alkenyl groups, comprising from 1 to 12 carbon atoms, preferably from 3 to 10 carbon atoms .

Advantageously, the compound with a hindered amine function is chosen from diphenylamine compounds, preferably substituted, in particular substituted on at least one of the positions in para of the amine function, by at least one alkyl or alkenyl group, comprising from 1 to 12 carbon atoms, preferably 3 to 10 carbon atoms.

In other words, the compound containing a hindered amine function can advantageously be of the following formula (I):

[Chem 3]

in which R 1 and R 2 are chosen, independently of one another, from a hydrogen atom, alkyl or alkenyl groups, preferably alkyl, linear or branched, comprising from 1 to 12 carbon atoms, preferably from 3 to 10 carbon atoms.

According to a particular embodiment, the compound with a hindered amine function is of formula (I) above, in which at least one of R 1 and R 2 is an alkyl or alkenyl group, preferably alkyl, linear or branched, comprising from 1 to 12 carbon atoms, preferably 3 to 10 carbon atoms.

Preferably, it is of formula (I) above, in which R 1 and R 2 are chosen, independently of one another, from alkyl or alkenyl groups, preferably alkyl, linear or branched, comprising from 1 to 12 atoms. carbon, preferably from 3 to 10 carbon atoms.

Preferably, R 1 and R 2 are in the para position of the amine function.

In other words, the compound with a hindered amine function can advantageously be of formula (G):

[Chem 4]

in which R 1 and R ₂ are as defined above.

Advantageously, R 1 and R ₂ , identical or different, represent alkyl groups, linear or branched, C 1 to C ₁₂ , preferably C ₃ to C ₁₀ , for example chosen from octyl and butyl groups, linear or branched.

Compounds with a hindered amine function can be commercially available, or else prepared according to synthetic methods known to those skilled in the art.

By way of example, mention may be made of p, p-butyl-octyl-diphenylamine.

The compounds with a hindered amine or phenolic function can also be compounds of sterically hindered phenol type.

The compounds of sterically hindered phenol type are preferably compounds comprising a phenol group of which at least one carbon atom other than that bearing the hydroxyl function and forming part of the phenyl group bears a hydroxyl radical, a linear or branched C _1- alkyl. ₁₀ , a dialkylaminoalkyl group, or a styryl group. Preferably, the sterically hindered phenols are chosen from compounds comprising a phenol group in which at least one carbon vicinal of the carbon carrying the alcohol function is substituted by at least one group chosen from a C 1 -C 10 alkyl group and a hydroxyl function.

In other words, the compound with a hindered phenolic function can be a sterically hindered phenol of the following formula (II):

[Chem 5]

in which :

at least one of R ¹ and R ² represents an alkyl group C ₁ -C _10, preferably an alkyl group _-C-O C, preferably alkyl C _4, for example tert butyl; or a hydroxyl group;

the carbon atoms of the benzene ring, other than those bearing the groups R ¹ , R ² and OH being optionally substituted.

In particular, the compound with a hindered phenolic function can be of the following formula (IG):

[Chem 6]

in which

at least one of R ¹ and R ² represents an alkyl group Ci-Cio, preferably an alkyl group in Ci-C _O, preferably a C4 alkyl group, for example tert-butyl; or a hydroxyl group;

n being an integer between 0 and 3;

R being chosen, independently of one another, from C 1 -C 10 alkyl groups, optionally substituted by one or more C 2 to C 10 alkoxycarbonyl groups such as an octyloxycarbonyl group and / or by one or more aryl groups, the aryl group (s) themselves being optionally substituted with one or more alkyl groups; and a hydroxyl group.

As examples of compounds of sterically hindered phenol type, mention may be made of di-t-butyl-2,6-methyl-4-phenol (BHT), t-butyl hydroquinone (TBHQ), 2,6 and 2. , 4 di-t-butyl phenol, 2,4-dimethyl-6-t-butyl phenol, pyrogallol, octyl-3,5-di-tert-butyl-4-hydroxy-hydrocinnamate, alone or as a mixture .

Preferably, the compound of sterically hindered phenol type is chosen from compounds, called “alkylphenols”, comprising a phenol group having, on at least one of the ortho positions of the hydroxyl function, preferably on the two ortho positions, an alkyl group at steric hindrance, preferably _Ci-Cio, especially CI _C-O, in particular an alkyl group C _4, preferably tert-butyl.

In particular, it may be a compound of the abovementioned formula (II), in particular of the abovementioned formula (IG), in which at least one of R ¹ and R ² , or even the two groups R ¹ and R ² , is (are) chosen (s) from C 1 -C 10 alkyl groups, preferably C 1 -C 6 alkyl groups. preferably a C4 alkyl group, preferably tert-butyl.

Compounds with a hindered phenolic function can be commercially available, or else prepared according to synthetic methods known to those skilled in the art.

As an example of a preferred sterically hindered phenol compound, there may be mentioned octyl-3,5-di-tert-butyl-4-hydroxy-hydrocinnamate or 2,6-di-tert-butylphenol. As an example of a still more preferred sterically hindered phenol compound, there may be mentioned octyl-3,5-di-tert-butyl-4-hydroxy-hydrocinnamate.

According to a preferred embodiment, the compound of sterically hindered aromatic or phenolic amine type is chosen from p, p'-butyl-octyl-diphenylamine, octyl-3,5-di-tert-butyl-4-hydroxy- hydrocinnamate, 2,6-di-tert-butylphenol, and mixtures thereof.

According to an even more preferred embodiment, the compound of sterically hindered aromatic or phenolic amine type is chosen from p, p'-butyl-octyl-diphenylamine, octyl-3,5-di-tert-butyl-4-. hydroxy-hydrocinnamate, and mixtures thereof.

The invention is not limited to the aromatic amine or hindered phenol compounds described above. Other compounds with a sterically hindered amine or phenol function, in particular known as anti-oxidants, can be used as anti-corrosion additives according to the invention.

In the context of the invention, by:

- alkyl, a saturated, linear or branched aliphatic group; for example, a C _x to C _y alkyl represents a hydrocarbon chain of x to y carbon atoms, linear or branched;

- alkenyl, an unsaturated, linear or branched aliphatic group; for example, a C _x to C _y alkenyl group represents an unsaturated carbon chain of x to y carbon atoms, linear or branched;

- alkoxy, an -O-alkyl radical, in which the alkyl group is as defined above;

- aryl, a mono- or polycyclic aromatic group, in particular comprising between 5 and 10 carbon atoms. By way of example of an aryl group, mention may be made of phenyl, tolyl or naphthyl groups. Advantageously, the said compound (s) with a sterically hindered amine or phenolic function used according to the invention are chosen from:

- aromatic amines, in particular as described above, in particular diarylaromatics, and more particularly diphenylamines, preferably substituted, advantageously in the para position of the amine function, by at least one C1-C12 alkyl group;

- Sterically hindered phenols, in particular as defined above, and preferably compounds comprising a phenol group of which at least one vicinal carbon of the carbon carrying the alcohol function is substituted by at least one C 1 -C 10 alkyl group, preferably in CI- _C6 , especially C4, in particular tert-butyl; and

- their mixtures.

It is understood, in the context of the present invention, that a compound with a sterically hindered amine or phenolic function can be in the form of a mixture of at least two compounds with a sterically hindered amine or phenolic function, for example of a mixture of at least one compound with a sterically hindered amine function and at least one compound with a sterically hindered phenol function.

The compound (s) with a sterically hindered amine or phenolic function, 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 0 , 1% to 3% by mass, and more particularly from 0.1% to 1% by mass, relative to the total mass of the lubricating composition.

Advantageously, a lubricating composition considered according to the invention does not include other anti-corrosion additives distinct from compounds containing a sterically hindered amine or phenolic function. According to a particular embodiment, a lubricating composition used according to the invention is free of anti-corrosion additive of triazole type or of succinimide type.

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; polysulfide additives, in particular sulfur olefins, amine phosphates, phospho-sulfur additives such as alkylthiophosphates, and mixtures thereof.

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 7]

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

1, 2, 5 -thiadiazole 1, J, 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 8]

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

3, 4-dImercapto-l. 2, 5 -thia diazole 2, J-dium-apt-1. 3, 4 -diia diazole The dimercaptothiadiazole derivatives are more particularly molecules or mixture of molecules based on 4,5-dimercapto-l, 2,3-thiadiazole, 3,5-dimercapto-l, 2,4-thiadiazole, 3,4-dimercapto- 1,2,5-thiadiazole or 2,5-dimercapto-1,3,4-thiadiazole, as represented above, in which at least one of the substitutions = S, or even both substitutions = S on the ring thiadiazole is replaced by a substituent:

[Chem 9]

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

[Chem 10]

in which the group (s) 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, even 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, Ri represent, independently of one another, linear alkyl groups, C1 to C24, preferably C2 to Cis, especially C4 to C i _6, more particularly Cs to C12 and preferably C12.

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 polysulfide 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 may comprise from 0.01% to 5% by mass, in particular from 0.1% to 3% by mass and more particularly from 0.1% to 1% by mass of additive (s ) anti-wear amines and / or sulfur compounds, preferably of thia (di) azole type and more preferably chosen from derivatives of dimercaptothiadiazole.

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 with a sterically hindered amine or phenolic function 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 compounds with a sterically hindered amine or phenolic function, in particular chosen from:

. aromatic amines, in particular as described above, in particular diarylaromatics, and more particularly diphenylamines, preferably substituted, advantageously in the para position of the amine function, by at least one C1-C12 alkyl group;

. sterically hindered phenols, in particular as defined above, and preferably 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 C 1 -C 10 alkyl group -C _O, especially C _4, especially tert-butyl;

and their mixtures; and

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

A composition used according to the invention may comprise, in addition to one or more additives with a sterically hindered amine or phenolic function 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.

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 glycol (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.

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 or III. 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), by compared to its total mass.

Complementary additives

A lubricating composition suitable for the invention can also further comprise all types of additives, distinct from additives with a sterically hindered amine or phenolic function 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 the 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) with a sterically hindered amine or phenolic function and of said amine (s) and / or sulfur (s) additive (s) used according to the invention.

Such additives, known to those skilled in the art in the field of lubricating and / or cooling propulsion systems for electric or hybrid vehicles, can be chosen from friction modifiers, detergents, extreme pressure additives, anti-foam agents, pour point lowering additives, dispersants, antioxidants distinct from compounds containing a sterically hindered amine or phenolic function according to the invention, pour point depressants, anti-foam agents and their mixtures.

Advantageously, a composition suitable for the invention comprises at least one additional additive chosen from friction modifiers, detergents, extreme pressure additives, anti-foam agents, pour point lowering additives, dispersants, antioxidants distinct from compounds with a sterically hindered amine or phenolic function according to the invention, 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 monoesters and polyols, alkoxylated amines, alkoxylated fatty amines, fatty epoxides, fatty borate epoxides; fatty amines or fatty acid glycerol esters. According to the invention, the compounds fatty compounds include 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 may comprise at least one antioxidant additive distinct from compounds with a sterically hindered amine or phenolic function, as defined according to the invention.

The antioxidant additive generally helps to delay the degradation of the composition in use. 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.

Antioxidant additives, distinct from compounds with a sterically hindered amine or phenolic function can be for example copper compounds, for example copper thio- or dithio-phosphates, copper salts and carboxylic acids, dithiocarbamates, sulphonates, copper 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.

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.

Advantageously, the lubricating composition used in the present invention does not include an antioxidant other than compounds with a sterically hindered amine or phenolic function, as defined according to the invention.

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

Detergent additives generally make it possible to reduce the formation of deposits on the surface of metal parts by dissolving the 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 metal 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 comprise 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 (s), relative to the total weight of the composition. According to a particular embodiment, a lubricating composition used according to the invention is free from a dispersant additive 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 comprise at least one pour point depressant additive (also called “PPD” agents for “Pour 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 of anti-corrosion additive of triazole type and of dispersant additive of succinimide type.

In terms of formulation of such a lubricating composition, the said compound (s) containing a sterically hindered amine or phenolic function may be added to an oil or mixture of base oils, then the other additional additives, including the one or more. anti-wear additives amine (s) and / or sulfur (s), added.

Alternatively, said compound (s) with a sterically hindered amine or phenolic function 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.

Alternatively, said additive (s) with a sterically hindered amine or phenolic function according to the invention can be combined with one or more additional additives, and the “packet” of additives thus formed added to an oil or mixture of oils of based.

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, in particular ranging from 3 to 10 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, in particular from 15 to 70 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;

and their mixtures;

- 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 friction modifiers, detergents, extreme pressure additives, anti-foaming agents, pour point lowering additives, dispersants, antioxidants other than amine-functional compounds or sterically hindered phenolic according to the invention, and mixtures thereof.

- from 0.01% to 5% by weight, in particular from 0.1% to 3% by weight, and more particularly from 0.1% to 1% by weight, of one or more compounds with a sterically hindered amine or phenolic function, in particular chosen from:

. sterically hindered phenols, in particular as defined above, and preferably 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 C 1 -C 10 alkyl group -C _O, in particular C4, especially tert-butyl;

and their mixtures; and

- from 0.01% to 5% by mass, in particular from 0.1% to 3% by mass, and more particularly from 0.1% to 1% by mass, of one or more anti-wear additives amine and / or sulfur , preferably one or more amino and sulfur antiwear additives, and more preferably chosen from thia (di) azole type compounds, in particular dimercaptothiazole derivatives;

- 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 weight of one or more additives chosen from friction modifiers, detergents, extreme -pressure additives, anti-foam agents, pour point lowering additives, dispersants, antioxidants distinct from compounds with a sterically hindered amine or phenolic function according to the invention, 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 compounds with a sterically hindered amine or phenolic function, in particular as defined above, and one or more anti-wear amine additives and / or sulfur compounds, preferably derivatives of dimercaptothiazole, 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.

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 in particular subjected to high mechanical stresses and poses problems of fatigue wear. It is therefore necessary to lubricate the bearing in order to increase its life. Also, the reducer is subjected to strong stresses in friction 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 can 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 composition C1 comprising an amine and sulfur anti-wear additive, of the dimercaptothiadiazole type and free of additive containing a sterically hindered amine or phenolic function; and

a composition C2 comprising said anti-wear additive of dimercaptothiadiazole type, and an additive with a sterically hindered amine function (p, p'-butyl-octyl-diphenylamine). a composition C3 comprising said anti-wear additive of dimercaptothiadiazole type, and an additive with a sterically hindered phenolic function (octyl-3,5-di-tert-butyl-4-hydroxy-hydrocinnamate).

Compositions C1 to C3 comprise, in addition to the aforementioned compounds, a group V 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 70 μm.

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 (compositions C2 and C3 being compositions according to the invention and composition C1 being a composition serving as comparative).

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] L

^{R = px} s

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 μm (loss of diameter). The lower the value obtained, the better the anti-corrosion properties of the composition evaluated.

A composition is considered to be "non-corrosive" when the loss in diameter of the copper wire studied is less than or equal to 2 μm after immersion for 80 hours, in particular less than or equal to 0.3 μm after immersion for 20 hours. hours in the composition.

[Table 3]

It emerges from these results that the addition of a compound with a sterically hindered amine or phenolic function according to the invention makes it possible to reduce the corrosion effects induced by the amine and sulfur antiwear additive.

Claims

1. Use of at least one compound having at least one sterically hindered amine or phenolic function, as an anti-corrosion additive in a lubricating composition, intended for a propulsion system of an electric or hybrid vehicle and comprising one or more several additive (s) anti-wear amine (s) and / or sulfur (s).

2. Use according to claim 1, wherein said compound exhibiting at least one sterically hindered amine or phenolic function is chosen from aromatic amines, in particular compounds of diarylamine type and more particularly of diphenylamine type, sterically hindered phenols, in particular. alkylphenols, and mixtures thereof.

3. Use according to the preceding claim, in which the compounds of aromatic amine type are chosen from diarylamines, preferably of formula

TJ „ ^" KTΉG

1V6 “1 JnL- TJK ?.„?

wherein R 6 and R7 are selected, independently of each other, from:

- a phenyl group, optionally substituted, preferably at the para of the amine function, by hydrocarbon groups, in particular chosen from alkyl or alkenyl groups, comprising from 1 to 12 carbon atoms, preferably from 3 to 10 carbon atoms ; and

- a naphthyl group, optionally substituted, preferably at the para of the amine function, by hydrocarbon groups, in particular chosen from alkyl or alkenyl groups, comprising from 1 to 12 carbon atoms, preferably from 3 to 10 carbon atoms ,

and more preferably of formula (I):

in which R 1 and R 2 are chosen, independently of one another, from a hydrogen atom, alkyl or alkenyl groups, preferably alkyl, linear or branched, comprising from 1 to 12 carbon atoms, preferably from 3 to 10 carbon atoms;

and in particular of formula (G):

in which R 1 and R 2, identical or different, represent alkyl groups, linear or branched, C 1 to C ₁₂ , preferably C ₃ to Cio, for example chosen from octyl and butyl groups, linear or branched.

4. Use according to any one of claims 2 to 3, wherein the sterically hindered phenol compounds are of formula (IG)

in which

at least one of R ¹ and R ² represents an alkyl group C1-C10, preferably an alkyl group in Ci-C _O, preferably a C4 alkyl group, for example tert-butyl; or a hydroxyl group;

n being an integer between 0 and 3;

5. Use according to any one of claims 1 to 4, wherein said compound with a sterically hindered amine or phenolic function is chosen from p, p'-butyl-octyl-diphenylamine, roctyl-3,5-di-tert-. butyl-4-hydroxy-hydrocinnamate, 2,6-di-tert-butylphenol, and mixtures thereof.

6. Use according to any one of the preceding claims, in which the amino and / or sulfur antiwear additive is chosen from derivatives of dimercaptothiadiazole, in particular derivatives of 2,5-dimercapto-l, 3,4-. thiadiazole of the following formulas taken alone or as a mixture:

in which the group (s) 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, even 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.

7. Use according to any one of the preceding claims, in which the said compound (s) containing a sterically hindered amine or phenolic function 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 0.1% to 1% by mass, relative to the total mass of the lubricating composition and / or said anti- additive (s). wear 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 0.1% to 1% by mass, relative to the total mass of the lubricating composition.

8. Use of a lubricating composition comprising one or more compound (s) comprising at least one sterically hindered amine or phenolic function, as anti-corrosion additive (s), and one or more anti-wear additive (s) amine (s) and / or sulfur (s), 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.

9. Use according to the preceding claim, wherein the compound (s) comprising at least one sterically hindered amine or phenolic function are as defined according to any one of claims 2 to 5 and 7; and / or the amino and / or sulfur antiwear additive (s) are as defined according to any one of claims 6 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.