WO2020260458A1

WO2020260458A1 - Use of a succinimide compound as an anti-corrosion additive in a lubricant composition for a propulsion system of an electric or hybrid vehicle

Info

Publication number: WO2020260458A1
Application number: PCT/EP2020/067820
Authority: WO
Inventors: Shimin Zhang; Hakim EL-BAHI; Julien Guérin
Original assignee: Total Marketing Services
Priority date: 2019-06-28
Filing date: 2020-06-25
Publication date: 2020-12-30
Also published as: EP3990593A1; CN114096645B; CN114096645A; KR20220032057A; JP2022538637A; FR3097873B1; FR3097873A1; US20220364010A1; MX2021015548A

Abstract

. The invention relates to the use of at least one succinimide compound 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 for lubricating a propulsion system of an electric or hybrid vehicle.

Description

Title: USE OF A SUCCINIMIDE-TYPE COMPOUND AS AN ANTI-CORROSION ADDITIVE IN 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 succinimide type 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, 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.

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 the context of the implementation of lubricants for vehicle engine systems electric or hybrid, whether 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 succinimide type, 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 additives. (s) anti-wear amine (s) and / or sulfur (s).

Compounds of succinimide type, such as for example polyalkylene succinimides such as polyisobutylene succinimides (PIBSI), have already been proposed as dispersants, for example in lubricants for vehicle engines, as described for example in application WO 2014/096328.

To the knowledge of the inventors, however, it has never been proposed to use compounds of the succinimide type, as an anti-corrosion additive, in the context of the use of a lubricant for a propulsion system. an electric or hybrid vehicle, 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 of succinimide type make it possible to effectively reduce the corrosion effects induced by amine and / or sulfur antiwear additives.

Thus, the addition of at least one compound of succinimide type advantageously makes it possible to improve the anti-corrosion properties of a lubricant comprising one or more anti-wear additive (s) 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 succinimide-type compound (s) 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 corrosion problems, discussed previously. 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 1.3 μm after immersion for 80 hours, in particular less than or equal to to 0.8 µm after immersion for 40 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 hi) The resistivity must 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 succinimide-type compound used according to the invention is chosen from polyalkylene mono- or bis-succinimides, such as polyisobutene (PIB) mono- or bis-succinimides; their borated derivatives; their succinic anhydride derivatives such as polyisobutylene succinic anhydrides (PIBSA); compounds obtained by opening such a succinic anhydride ring such as pentaerythritol ester succinimide PIBs; and their mixtures.

Preferably, the compound of succinimide type is chosen from:

polyalkylene bis-succinimides, the alkyl chain of which is optionally linked to the succinimide via a - (0 = O¾) - group, in particular polyisobutylene (PIB) bis-succinimides whose alkyl chain is optionally linked to succinimide via a - (C = CH2) - group, and their borated derivatives, the two groups succinimides being linked to one another via their respective nitrogen atom via an alkylene group or a polyamine group, in particular polyalkyleneamine;

polyalkylene mono-succinimides whose alkyl chain is optionally linked to the succinimide via a group - (0 = O¾) -, in particular polyisobutylene (PIB) monosuccinimides whose alkyl chain is optionally linked to the succinimide via a group - (C = CH2) -, and their borated derivatives, substituted on the nitrogen atom by a polyamine group, in particular polyalkyleneamine; and

their mixtures.

The introduction, into a lubricating composition intended for a propulsion system of an electric or hybrid vehicle, of one or more compound (s) of succinimide 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 amine and sulfur anti-wear 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 exhibits good stability, in particular to oxidation, as well as good properties in terms of electrical insulation.

The present invention also relates to the 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 composition lubricant comprising:

one or more compounds of succinimide type 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 of succinimide type as defined in the invention, as anti-corrosion additive, 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 compound (s) of succinimide type as anti-corrosion additives according to the invention will emerge better 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.

Unless specified otherwise, the expression "comprising a" should be understood as "comprising at least one".

Brief description of the drawings

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

detailed description

SUCCINIMIDE ANTI-CORROSION 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 compound of the succinimide type.

As mentioned above, many succinimide-type compounds have already been proposed for their use as dispersing agents, such as, for example, polyalkylene mono- or bis-succinimides, such as polyisobutene (PIB) mono- or bis-succinimides; their borated derivatives; their succinic anhydride derivatives, as by example polyisobutylene succinic anhydrides (PIBSA); compounds obtained by opening such a succinic anhydride ring, such as for example polyisobutylene pentaerythritol ester succinimides.

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 so-called “succinimide-type” compounds are compounds comprising at least one succinimide group, in other words a group of following formula (i):

[Chem 1]

or a borate derivative (B-O bonds) thereof; or a succinic anhydride derivative of such a succinimide group, or a compound obtained by opening the succinic anhydride ring.

As already mentioned above, the compounds of succinimide type can be of various kinds. They can be mono-succinimide or bis-succinimide compounds.

Preferably, the compound of succinimide type is chosen from compounds comprising at least one substituted succinimide group, in particular of the following formula (ii): [Chem 2]

or a borated derivative (BO bonds) of such a substituted succinimide group of formula (ii), or a succinic anhydride derivative of such a substituted succinimide group of formula (ii), or a compound obtained by opening the succinic anhydride ring, in which R ¹ represents a hydrocarbon group, preferably comprising from 8 to 400 carbon atoms.

R ¹ can be more particularly chosen from linear or branched C6 to C400 alkyl groups, in particular C50 to C200, linear or branched C6 to C400 alkenyl groups, in particular C50 to C200, aryl groups in Cr, to Cio, arylalkyl groups and alkylaryl groups.

Preferably, R ¹ represents a long alkyl chain, preferably branched, Cs to C400, in particular C50 to C200 or a long alkenyl chain, preferably branched, Cx to C400, in particular C50 to C200 comprising a single double bond of which one of the two carbon atoms is directly linked to the succinimide ring.

Advantageously, R ¹ represents a polyalkylene group, preferably having an average molecular mass Mw of between 140 and 50,000, in particular between 2,000 and 30,000.

According to a particular embodiment, R ¹ represents a poly isobutylene group, preferably with a number-average molecular mass of between 140 and 30,000, in particular between 2,000 and 20,000, or even 2,000 and 7,000 and in particular between 3,000 and 5,000. According to another particular embodiment, R ¹ represents a polyisobutylene group, preferably with a number-average molecular mass of between 140 and 30,000, in particular between 2,000 and 20,000, or even 2,000 and 7,000 and in particular between 3,000 and 5,000, linked to the succinimide group via a group - (0 = O¼) - and is of formula (A) which follows: [Chem 3]

in which the symbol * indicates the point of attachment of this group to the succinimide group, and n represents an integer ranging from 6 to 500.

Thus, according to a particular embodiment, the compound of succinimide type comprises at least one substituted succinimide group of formula (ii), or a borate derivative of said group (ii), or a succinic anhydride derivative of said group (ii), or a compound obtained by opening the succinic anhydride ring, in which R ¹ represents a hydrocarbon-based group, preferably comprising from 8 to 400 carbon atoms, in particular a polyalkylene group optionally linked to the succinimide group via a - (C = CH 2) - group, preferably having a mass average molecular mass Mw between 140 and 50,000, in particular between 2,000 and 30,000, and more particularly a polyisobutylene group optionally linked to the succinimide group via a - (C = CH2) - group, preferably of average molecular weight Mw between 140 and 30,000, in particular between 2,000 and 20,000 or even between 2,000 and 7,000 and in particular between 3,000 and 5,000.

More particularly, the compound of succinimide type can be chosen from mono-succinimide compounds comprising a substituted succinimide group of above-mentioned formula (ii) and bis-succinimide compounds comprising two substituted succinimide groups, in particular of above-mentioned formula (ii), said succinimide groups being more particularly linked at their summit bearing a nitrogen atom via a polyamine group.

According to a particular embodiment, the compound of succinimide type used according to the invention corresponds to the following formula (I):

[Chem 4]

or one of its borated derivatives,

where A represents an alkylene group, linear or branched, C2 to C24, preferably C ₂ to C ₆ ;

R ¹ is as defined above, for example a polyisobutylene group optionally optionally linked to the succinimide group via a group - (C = CH2) - x represents 0 or an integer ranging from 1 to 6, preferably x is 2, 3 or 4 ;

R ² and R ³ are chosen, independently of one another, from a hydrogen atom, a linear or branched alkyl group, in particular from C1 to C25; an alkoxy group, in particular C 1 to C ₁₂ , an alkenyl group, in particular C ₂ to C ₁₂ , optionally carrying one or more hydroxyl and / or amine functions;

or R ² and R ³ together form, with the nitrogen atom carrying them, an optionally substituted succinimide group, preferably a succinimide group substituted with an R ¹ group as defined above.

According to a first variant embodiment, a compound of succinimide type used according to the invention can be a mono-succinimide compound of above-mentioned formula (I) in which R ² and R ³ are chosen, independently of one another. , from a hydrogen atom, a linear or branched alkyl group, in particular C 1 to C ₂₅ ; an alkoxy group, in particular C 1 to C ₁₂ , an alkenyl group, in particular C ₂ to C ₁₂ , optionally carrying one or more hydroxyl and / or amine functions.

Preferably, a compound of succinimide type used according to the invention is of formula (I) above in which R ² and R ³ represent hydrogen atoms.

In other words, a compound of succinimide type used according to the invention can be of the following formula (II):

[Chem 5]

or one of its borated derivatives,

where: R ¹ is as defined above, in particular R ¹ represents a polyalkylene group optionally linked to the succinimide group via a group - (0 = O¾) -, in particular polyisobutylene optionally linked to the succinimide group via a group - (C = CH ₂ ) -,

A is as defined above, preferably represents at least one of the following segments -CH2-CH2-, -CH2-CH2-CH2-, -CH ₂ -CH (CH) -; and

y represents an integer between 1 and 6, in particular y represents 2, 3 or 4. According to another variant embodiment, a compound of succinimide type used according to the invention can be a bis-succinimide compound of formula ( I) above in which R ² and R ³ together form, with the nitrogen atom carrying them, an optionally substituted succinimide group, preferably a succinimide group substituted with an R ¹ group as defined above.

Advantageously, a bis-succinimide-type compound used according to the invention may be of the following formula (III):

[Chem 6]

or one of its borated derivatives, where:

R ¹ , identical or different, are as defined above;

z represents an integer between 0 and 10, preferably between 2 and 6;

s represents an integer between 2 and 6, preferably between 2 and 4.

Preferably, the compound of bis-succinimide type may be of formula (III) in which R ¹ represent polyalkylene groups, in particular polyisobutylene groups, preferably with a molecular mass of between 150 and 15,000, in particular between 500 and 2000 and in particular between 500 and 1500.

The borated derivatives of the compounds of succinimide type of formula (I), (II) or (III) above can be obtained from non-borated compounds of succinimide type, by reaction with borates, for example with boric acid, in particular to achieve a concentration of 0.1 to 3% by mass, in particular from 1 to 2% by mass of boron in the succinimide compound.

Among the succinic anhydride derivatives suitable for the invention, mention may be made of polyisoalkylene succinic anhydrides, in particular polyisobutylene succinic anhydrides (called “PIB SA”) such as the following compound, of molecular mass in number Mn of between 300 and 30,000 and with a molecular mass by mass Mw of between 300 and 30,000:

[Chem 7]

wherein R is a polyisobutylene group.

Among the compounds obtained by opening the succinic anhydride ring, there may be mentioned in particular the polyalkylenes pentaerithritol ester succinimides such as, for example, the polyisobutylene pentaerithritol ester succinimides of the following formulas, of molecular mass in number Mn of between 300 and 30,000 and of molecular mass in mass. Mw between 300 and 30,000:

[Chem 8]

wherein PIB represents polyisobutylene;

[Chem 9]

wherein PIB represents polyisobutylene.

In the context of the invention, by:

alkyl, a saturated, linear or branched aliphatic group; for example, Cx to Cz alkyl represents a linear or branched hydrocarbon chain of x to z carbon atoms; alkylene represents a divalent alkyl group. For example, a C _x -C _z alkylene group represents a divalent hydrocarbon chain of x to z carbon atoms, linear or branched;

alkenyl, an unsaturated, linear or branched aliphatic group; for example, a Cx to Cz alkenyl group represents an unsaturated carbon chain of x to z 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 additive of succinimide type (mono or bis-succinimide) is chosen from polyalkylene succinimides (in other words the compounds comprising at least one group of above-mentioned formula (ii) where R ¹ is a polyalkylene group optionally linked to the succinimide group via a group - (0 = O¾) -) and in particular polyisobutylene (PIB) succinimides, the polyisobutylene part of which is optionally linked to the succinimide group via a group - (0 = O¾) -, and their borated derivatives.

According to a particular embodiment, the additive of succinimide type is chosen from polyalkylene succinimides whose alkyl chain is optionally linked to succinimide via a - (0 = O¾) - group, in particular polyisobutylene (PIB) succinimides whose chain alkyl is optionally linked to succinimide via a group - (0 = O¾) -, and their borated derivatives, substituted on the nitrogen atom by a polyamine group, in particular polyalkyleneamine, for example polyethylene amine.

Preferably, the additive of succinimide type is chosen from the mono- or bis-succinimides of the above-mentioned formula (I), in particular the mono-succinimides of the above-mentioned formula (II), the bis-succinimides of the above-mentioned formula (III), and their mixtures.

According to a particularly preferred embodiment, the additive of succinimide type is chosen from:

polyalkylene bis-succinimides, the alkyl chain of which is optionally linked to the succinimide via a - (0 = O¾) - group, in particular polyisobutylene (PIB) bis-succinimides whose alkyl chain is optionally linked to the succinimide via a - (C) group = CH2) -, and their borated derivatives, the two succinimide groups being linked one to the other via their respective nitrogen atom via an alkylene group or a polyamine group, in particular polyalkyleneamine or even polyethyleneamine;

polyalkylene mono-succinimides whose alkyl chain is optionally linked to the succinimide via a group - (0 = O¾) -, in particular polyisobutylene (PIB) monosuccinimides whose alkyl chain is optionally linked to the succinimide via a group - (C = CH2) -, and their borated derivatives, substituted on the nitrogen atom by a polyamine group, in particular polyalkyleneamine or even polyethyleneamine; and

their mixtures.

According to an even more particularly preferred embodiment, the additive of succinimide type is chosen from the following compounds:

[Chem 10]

wherein n is from 6 to 500, preferably is 90; and R is a linear or branched, C2 to C24, preferably C2 to C6 alkylene _OR a group -R ”- (NH-R ') x- in which R' and R” represent, independently one of the other a linear or branched alkylene, C2 to C24, preferably from C2 to _C6 and x is an integer ranging from 1 to 6, preferably x is 2, 3, 4 or 5. It is more precisely a bis-succinimide whose average molecular mass Mn is between 3000 and 4000, preferably is 3410; the average molecular mass Mw is between 5000 and 6000, preferably is 5225; the polydispersity index Ip is between 1.25 and 2, preferably is 1.5;

[Chem 11]

where n is from 10 to 350, preferably is 65; and R is a linear or branched alkyl, C1 to C24, preferably from C2 to G or a group - (R '- (NH) yH in which R' represents a linear or branched, C2 to C24 alkylene, preferably from C2 to C>,, and y is an integer ranging from 1 to 6, preferably x is 2, 3 or 4. It is more precisely a succinimide PIB whose average molecular mass Mn is between 800 and 18,000 preferably is 3519; the average molecular weight Mw is between 1000 and 20,000, preferably is 6220; the polydispersity index Ip is between 1.5 and 2.3, preferably is 1 , 6; and

their mixtures.

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

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

For example, succinimide-type compounds can be synthesized by condensation of an optionally substituted succinic anhydride, for example of a succinic anhydride substituted with a polyisobutylene group, with a poly (alkyleneamine). Succinic anhydride substituted with a polyisobutylene group (PIB) can be obtained beforehand, for example by reaction of maleic anhydride with methyl vinylidene polyisobutene.

The invention is not limited to the succinimide-type compounds specifically described above. Other succinimide-type compounds, in particular known as dispersants, can be used as anti-corrosion additives according to the invention. The compound (s) of succinimide type, in particular as defined above, can be used in a lubricating composition according to the invention, in an amount of 0.01% to 10% by mass, in particular from 0.1% to 10% by mass, and more particularly from 0.5% to 8% 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 of succinimide type. According to a particular embodiment, a lubricating composition used according to the invention is free from anti-corrosion additive of triazole type or of compound type with an amine function or sterically hindered phenolic function.

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 (di) 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 which 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, in addition to the cyclic compounds containing one sulfur atom and one nitrogen atom per ring with five atoms, 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 12]

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

1 _* 2,5 -thiadiazole l, $ A -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 13]

4.5-Ilanercapto-1,2,3 -thiadiazole 3, 5-clinercapio-i _» 2,4 -thiadiazole

3 4-dimercapto 1, 2, 5 -thia diazole 2, 5-dimercapto-1, 3, 4 -thia 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 14]

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 15]

[Chem 16]

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, R independently of one another represent linear alkyl groups, Ci-C24, preferably C2 to Cis, in particular C4 to C _6, more preferably 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.

Polysulfide additives

The amine and / or sulfur anti-wear additive or additives used in a lubricating composition according to the invention can still be chosen from among sulfur-based anti-wear additives of the polysulfide 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 can comprise from 0.01 to 10% by mass, in particular from 0.1 to 5% by mass and more particularly from 0.5 to 3% by mass of anti-wear additive (s) 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 amino and / or sulfur additives, can be envisaged, provided that they do not affect the properties conferred by the combination. of said compound (s) of succinimide type and of said amino and / or sulfur antiwear additive (s) according to the invention.

A lubricating composition considered according to the invention may comprise from 0.01 to 15% by mass, in particular from 0.1 to 10% by mass and more particularly from 0.5 to 5% by mass of anti- additive (s). wear, including one or more amine and / or sulfur additives, as described above.

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 of succinimide type, in particular chosen from polyalkylene mono- or bis-succinimides and their borated derivatives, such as polyisobutene mono- or bis-succinimides and their borated derivatives, in particular chosen from compounds of formula ( I) above, preferably from the compounds of formula (II) and (III) as defined above; 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 of succinimide 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.

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 may also further comprise all types of additives, other than additives of succinimide 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 the amount 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 succinimide type and of or of said amine (s) and / or sulfur (s) additives 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, dispersants distinct from the succinimide-type compounds according to the invention, antioxidants, pour point depressants, anti-foaming agents and mixtures thereof. Advantageously, a composition suitable for the invention comprises at least one additional additive chosen from friction modifiers, viscosity index modifiers, detergents, extreme pressure additives, dispersants, antioxidants, point-d depressants. flow, anti-foam agents and mixtures thereof.

These additives can be introduced singly 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 G ACEA (Association European Automobile Manufacturers) and / or GARI (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 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 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. 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 free of ash or be 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 by at least one C 1 -C12 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 -Cio alkyl group, preferably an alkyl group. C _I -C _O, preferably a C4 alkyl group, preferably 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 a alkylene group or an alkenylene group, R ⁸ represents an alkyl group, an 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 is that of copper compounds, for example copper thio- or dithio-phosphates, copper and carboxylic acid salts, dithiocarbamates, sulphonates, phenates, copper 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, distinct from the succinimide-type compounds defined according to the invention.

The dispersing agent can be selected from Mannich bases.

A lubricating composition used according to the invention may for example comprise from 0.2 to 10% by weight of dispersing agent (s) distinct (s) from the compounds of succinimide type defined according to the invention, relative to to the total weight of the composition.

Advantageously, the lubricating composition used according to the invention does not include any dispersing agent (s), other than the succinimide-type compounds defined according to the invention.

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, mention may be made of polymethacrylates of alkyl, polyacrylates, polyarylamides, polyalkylphenols, polyalkylnaphthalenes, alkylated polystyrenes. In particular, a lubricating composition used according to the invention may be free from anti-corrosion additive of triazole type and from antioxidant additive of aromatic amine type or of sterically hindered phenol type.

In terms of formulation of such a lubricating composition, the said compound (s) of succinimide type may 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 succinimide type may 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, the said anti-corrosion additive (s) of succinimide type 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 base oils. .

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;

one or more additives of succinimide type, preferably chosen from polyalkylene mono- and bis-succinimides, such as polyisobutene mono- and bis-succinimides, and their borated derivatives; in particular chosen from the compounds of formula (I) above, preferably from the compounds of formula (II) and (III) as defined 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 as defined above;

optionally one or more additional additives chosen from friction modifiers, viscosity index modifiers, detergents, extreme pressure additives, dispersants, antioxidants, pour point depressants, anti-foam agents and their mixtures.

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

from 0.01% to 10% by weight, in particular from 0.1% to 10% by weight, and more particularly from 0.5% to 8% by weight, of one or more additives of succinimide type, preferably chosen from among polyalkylene mono- and bis-succinimides, such as polyisobutene mono- and bis-succinimides, and their borated derivatives; in particular chosen from the compounds of formula (I) above, preferably from the compounds of formula (II) and (III) as defined above;

from 0.01 to 10% by weight, in particular from 0.1 to 5% by weight, and more particularly from 0.5 to 3% by weight, of one or more amine and / or sulfur antiwear additives, preferably of 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 0.1% to 5% by mass of one or more additives chosen from friction modifiers, viscosity index modifiers, detergents, extreme pressure additives, dispersants, antioxidants, point depressants flow, anti-foaming 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 compounds of succinimide type, in particular as defined above, and one or more anti-wear amine and / or sulfur additives, of 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 to increase its lifespan. 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 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 and 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 antiwear additive, of the dimercaptothiadiazole type and free of additive of the succinimide type;

a C2 composition comprising said anti-wear additive of dimercaptothiadiazole type, and a dispersant additive of succinimide type, in accordance with the invention, more precisely a bis-succinimide of the following formula:

[Chem 17]

as defined above,

a C3 composition comprising said anti-wear additive of dimercaptothiadiazole type, and a dispersant additive of succinimide type, in accordance with the invention, more specifically a succinimide PIB of high molecular weight,

a C4 composition comprising said anti-wear additive of dimercaptothiadiazole type, and a dispersant additive of succinimide type, in accordance with the invention, more specifically a succinimide PIB of the following formula:

[Chem 18]

Compositions C1 to C4 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

Assessment method

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 to C4 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]

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 have the relation 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 the following table, and are expressed in μm (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 1.3 μm after immersion for 80 hours, in particular less than or equal to 0.8 μm after immersion. for 40 hours in the composition comprising said compound.

[Table 3]

It emerges from these results that the addition of a succinimide-type compound according to the invention makes it possible to reduce the corrosion effects induced by the amine and sulfur anti-wear additive.

Claims

1. Use of at least one compound of succinimide type, 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 anti-corrosion additive (s). wear amine (s) and / or sulfur (s).

2. Use according to claim 1, in which said compound of succinimide type is chosen from polyalkylene mono- or bis-succinimides, such as polyisobutene (PIB) mono- or bis-succinimides; their borated derivatives; their succinic anhydride derivatives, such as, for example, polyisobutylene succinic anhydrides (PIBSA); compounds obtained by opening such a succinic anhydride ring, such as for example the polyisobutylene pentaerythritol ester succinimides; and their mixtures.

3. Use according to any one of the preceding claims, wherein said succinimide-type compound comprises at least one substituted succinimide group of the following formula (ii):

or a borate derivative of said group (ii), or a succinic anhydride derivative of said group (ii), or a compound obtained by opening the succinic anhydride ring, in which R ¹ represents a hydrocarbon group, preferably comprising from 8 to 400 atoms of carbons, in particular a polyalkylene group optionally linked to the succinimide group via a - (C = CH2) - group, preferably having an average molecular mass Mw of between 140 and 50,000, in particular between 2,000 and 30,000, and more particularly a polyisobutylene group optionally linked to the succinimide group via a - (C = CH2) - group, preferably with an average molecular weight Mw of between 140 and 30,000, in particular between 2,000 and 20,000 or even between 2,000 and 7,000 and in particular between 3,000 and 5,000.

4. Use according to any one of the preceding claims, in which said compound of succinimide type is a mono-succinimide of the following formula (II):

or one of its borated derivatives,

in which :

R ¹ is as defined in claim 3, in particular R ¹ represents a polyalkylene group optionally linked to the succinimide group via a group - (0 = O¾) -, in particular R ¹ represents a polyisobutylene group optionally linked to the succinimide group via a group - (0 = WHERE) -,

A represents an alkylene group, linear or branched C ₂ -C _24, preferably C ₂ C _O; preferably represents at least one of the following segments -CH2-CH2-, -CH ₂ - CH2-CH2-, -CH ₂ -CH (CH) -; and

y represents an integer between 1 and 6, in particular y represents 2, 3 or 4.

5. Use according to any one of claims 1 to 3, wherein the succinimide compound is a bis-succinimide of the following formula (III):

or one of its borate derivatives

in which :

R ¹ , identical or different, are as defined in claim 3, in particular R ¹ represent polyalkylene groups optionally linked to the succinimide group via a - (0 = O¾) - group, in particular polyisobutylene groups optionally linked to the succinimide group via a group - (C = CH2) -;

z represents an integer between 0 and 10, preferably between 2 and 6;

s represents an integer between 2 and 6, preferably between 2 and 4.

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:

7. Use according to any one of the preceding claims, in which the said compound (s) of succinimide type is (are) present in a content ranging from 0.01% to 10% by mass, in particular of 0.1% to 10% by mass, and more particularly from 0.5% to 8% by mass, relative to the total mass of the lubricating composition, and / or said amine anti-wear additive (s) ( s) and / or sulfur (s) is (are) present in a content ranging from 0.01 to 10% by mass, in particular from 0.1 to 5% by mass and more particularly from 0.5 to 3% by mass, relative to the total mass of the lubricating composition.

8. Use of a lubricating composition comprising one or more compound (s) of succinimide type 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, in which the anti-corrosion additive (s) of succinimide type are as defined in any one of claims 2 to 5 and 7; and / or the amino and / or sulfur antiwear additive (s) are as defined in any one of claims 6 and 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.