WO2025083136A1 - Lubricant composition for motor vehicle transmission - Google Patents

Abstract

The present invention relates to a group of additives comprising: - at least one phosphite compound of formula (1), and - at least one thiadiazole compound corresponding to one of formulae (2), (3), (4) or (5), in which: R and R¹ represent, independently of each other, a hydrogen atom or a linear or branched, saturated or unsaturated hydrocarbon group comprising from 1 to 24 carbon atoms, said hydrocarbon group optionally comprising one or more heteroatoms, R² and R³ represent, independently of each other, a hydrogen atom or a linear or branched, saturated or unsaturated hydrocarbon group comprising from 1 to 24 carbon atoms, said hydrocarbon group optionally comprising one or more heteroatoms.

Description

Description

Title: Lubricating composition for automobile transmission.

Technical field

The present invention relates to the field of lubricating compositions, in particular for motor vehicles, in particular for lubricating the transmission components of motor vehicles, in particular the gears of thermal or electric engine transmissions.

State of the art

Automotive transmission components operate under heavy loads and at high speeds. The oils (also known as lubricating compounds or lubricants) for these transmissions must therefore be particularly effective in protecting parts against wear and fatigue, and in particular in protecting gear teeth against seizure.

Seizure occurs under high load conditions and can be assessed by monitoring visual deterioration.

Preventing this phenomenon involves reducing contact stresses through appropriate part geometry and reducing friction by preventing adhesion. The lubricating composition plays a role in this prevention process, primarily through the physicochemical reactivity of its additives.

Anti-wear and extreme pressure additives containing sulfur, phosphorus, or borates are generally added to give transmission oils anti-seize properties.

These additives can therefore have a beneficial effect on the durability of the lubricating oil incorporating them, but can however present disadvantages from a corrosion point of view, in particular of copper parts.

The inventors of the present invention have discovered that a specific combination of phosphorus and sulfur-containing additives can be implemented in a lubricating composition having good anti-corrosion properties towards copper, in addition to good durability properties. It is therefore an object of the present invention to provide a composition for lubricating manual or automatic transmission components, in particular transmission gears, preferably for electric vehicles, said composition having improved anti-corrosion properties as well as good durability.

Summary of the invention

More specifically, the present invention relates to an additive package comprising:

- at least one phosphite compound of formula (1), and - at least one thiadiazole compound corresponding to one of formulas (2), (3), (4) or (5),

[Chem 5]

dans lesquelles : [Chem 1]

[Chem 5]

in which:

R and R ¹ represent, independently of one another, a hydrogen atom or a linear or branched, saturated or unsaturated hydrocarbon group, comprising from 1 to 24 carbon atoms, said hydrocarbon group optionally comprising one or more heteroatoms,

R ² and R ³ represent, independently of one another, a hydrogen atom or a linear or branched, saturated or unsaturated hydrocarbon group, comprising from 1 to 24 carbon atoms, said hydrocarbon group optionally comprising one or more heteroatoms.

The dotted bonds mean that the bond can be double or single. If the bond is double inside the ring, the nitrogen atom attached to this double bond is not bonded to a hydrogen atom according to the valence rules. If the bond is double outside the ring, the sulfur atom is not bonded to ^R2 or ^R3 according to the valence rules. At least one of the dotted bonds is a double bond.

Preferably, the mass ratio between the phosphite compound of formula (1) and the thiadiazole compound ranges from 1/10 to 10/1, preferably from 1/5 to 5/1, more preferably from 1/2 to 2/1.

According to one embodiment, the additive package further comprises at least one dispersant, preferably a borated dispersant, more preferably a borated dispersant chosen from borated succinimides, more preferably from borated polyisobutene succinimides, said at least one dispersant preferably representing from 10 to 70% by weight, more preferably from 20 to 60% by weight, of dispersant(s), relative to the total weight of the additive package. Preferably, the mass ratio between the sulfur content and the phosphorus content provided by the phosphite compound(s) of formula (1) and the thiadiazole compound(s) ranges from 1/1 to 3.5/1.

According to one embodiment of the additive package:

- R and R ¹ represent, independently of one another, a hydrogen atom or a linear or branched alkyl group, comprising from 1 to 24 carbon atoms, preferably from 1 to 12 carbon atoms, more preferably from 2 to 8 carbon atoms, preferably R and R ¹ represent a linear or branched alkyl group, from 1 to 24 carbon atoms, preferably from 1 to 12 carbon atoms, more preferably from 2 to 8 carbon atoms, and/or

- said at least one thiadiazole compound corresponds to formula (2), in which R ² and R ³ independently of each other represent a hydrogen atom, a linear or branched alkyl group comprising from 6 to 18 carbon atoms, a -SR' group where R' can be a linear or branched alkyl group comprising from 6 to 18 carbon atoms.

According to one embodiment, the additive package according to the invention further comprises one or more thiophosphate compounds, the mass ratio between the thiadiazole compound(s) and the thiophosphate compound(s) ranging from 1/5 to 2/1, preferably from 1/2 to 1.5/1, preferably said at least one thiophosphate compound corresponding to formula (6):

dans laquelle : [Chem 6]

in which:

R ⁵ and R ⁶ represent, independently of one another, a hydrogen atom or a linear or branched, saturated or unsaturated hydrocarbon group, comprising from 1 to 24 carbon atoms, said hydrocarbon group optionally comprising one or more heteroatoms,

R ⁴ represents an OR ^4a group or an SR ^4a group where R ^4a represents a linear or branched, saturated or unsaturated hydrocarbon group, comprising from 1 to 24 carbon atoms, said hydrocarbon group optionally comprising one or more heteroatoms,

X represents a sulfur atom or an oxygen atom, it being understood that if X represents an oxygen atom then R ⁴ represents an SR ^4a group.

According to a preferred embodiment of the additive package:

- R ⁵ and R ⁶ represent, independently of one another, a hydrogen atom or a linear or branched alkyl group, comprising from 1 to 24 carbon atoms, preferably from 1 to 12 carbon atoms, more preferably from 2 to 8 carbon atoms, and/or

- X represents a sulfur atom, and/or

- R ⁴ represents an SR ^4a group where R ^4a represents an R ^4b COOH group where R ^4b represents a linear or branched alkyl group, comprising from 1 to 24 carbon atoms, preferably from 1 to 12 carbon atoms, more preferably from 2 to 8 carbon atoms.

According to one embodiment, the additive package further comprises at least one phosphate compound, preferably corresponding to formula (7):

dans laquelle : [Chem 7]

in which:

R ⁷ and R ⁸ are chosen independently of one another from a hydrogen atom or linear or branched, saturated or unsaturated hydrocarbon groups comprising from 4 to 24 carbon atoms, at least one of the two radicals R ⁷ or R ⁸ being a linear or branched, saturated or unsaturated hydrocarbon group comprising from 4 to 24 carbon atoms. According to one embodiment, the additive package comprises:

- at least 0.5% by weight, preferably from 0.5 to 20% by weight, more preferably from 1 to 10% by weight, or even from 2 to 5% by weight, of phosphite compound(s) of formula (1),

- at least 1% by weight, preferably from 1 to 20% by weight, more preferably from 2 to 15% by weight, or even from 3 to 10% by weight, of thiadiazole compound(s),

- optionally from 1 to 20% by weight, preferably from 2 to 15% by weight, preferably from 3 to 10% by weight, of compound(s) chosen from (i) a thiophosphate compound, preferably corresponding to formula (6), (ii) a phosphate compound, preferably corresponding to formula (7), and (iii) their mixture,

- possibly up to 100% by weight of base oil(s) and/or additive(s) other than phosphite, thiadiazole, phosphate and thiophosphate additives, relative to the total weight of the additive package.

The invention also relates to a lubricating composition comprising:

- at least 60% by weight of base oil(s), relative to the total weight of the lubricating composition,

- at least one package of additives according to the invention.

Preferably, the lubricating composition according to the invention comprises:

- from 80 to 99.5% by weight, preferably from 85 to 99% by weight, of base oil(s),

- from 0.5 to 20% by weight, preferably from 1 to 15% by weight, of the additive package, relative to the total weight of the lubricating composition.

According to a preferred embodiment, the lubricating composition according to the invention comprises:

- from 70 to 99% by weight, preferably from 85 to 99% by weight, of base oil(s),

- from 0.01 to 5% by weight, preferably from 0.05 to 1% by weight, of phosphite compound(s),

- from 0.01 to 5% by weight, preferably from 0.05 to 1% by weight, of thiadiazole compound(s), - optionally from 0.01 to 5% by weight, preferably from 0.05 to 1% by weight, of compound(s) chosen from (i) a thiophosphate compound, preferably corresponding to formula (6), (ii) a phosphate compound, preferably corresponding to formula (7), and (iii) their mixture,

- optionally from 1 to 20% by weight of dispersant(s), preferably from 1 to 15% by weight, more preferably from 2 to 10% by weight, of dispersant(s),

- optionally up to 100% by weight of additive(s) other than the phosphite, thiadiazole, thiophosphate, phosphate and dispersant additives, relative to the total weight of the lubricating composition.

Preferably, the lubricating composition according to the invention has a kinematic viscosity at 100°C ranging from 1 to 20 mm2/s, preferably from 1.5 to 15 mm2/s, more preferably from 2 to 10 mm2/s.

The invention also relates to the use of the additive package according to the invention, for preparing a lubricating composition intended to lubricate at least one mechanical part of a motor vehicle, said part preferably being a transmission member, and/or said motor vehicle preferably being an electric vehicle.

Preferably, the lubricating composition according to the invention is used to lubricate at least one mechanical part of a motor vehicle, said part preferably being a transmission member, and/or said motor vehicle preferably being an electric vehicle.

The lubricating composition according to the invention has improved anti-corrosion properties.

The lubricating composition according to the invention has the advantage of having very good properties for reducing the phenomenon of seizure.

The lubricating composition according to the invention also has good durability. The lubricating composition exhibits particularly satisfactory performance in both reducing corrosion and reducing wear even under heavy load, even in the absence of a zinc-based additive.

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

Unless otherwise stated, quantities in a product are expressed by weight, relative to the total weight of the product.

Detailed description

The present invention relates to a lubricating composition comprising:

- at least one base oil,

- at least one package of additives.

The additive package of the invention comprises:

- at least one phosphite compound of formula (1), and

- at least one thiadiazole compound corresponding to one of the formulas (2), (3), (4) or (5)

[Chem 1]

dans lesquelles : [Chem 3]

in which:

R and R ¹ represent, independently of one another, a hydrogen atom or a linear or branched, saturated or unsaturated hydrocarbon group, comprising from 1 to 24 carbon atoms, said hydrocarbon group optionally comprising one or more heteroatoms,

R ² and R ³ represent, independently of one another, a hydrogen atom or a linear or branched, saturated or unsaturated hydrocarbon group, comprising from 1 to 24 carbon atoms, said hydrocarbon group optionally comprising one or more heteroatoms.

The bond with the dotted line means that the bond can be double or single. If the bond is double, the nitrogen atom attached to this double bond is not bonded to a hydrogen atom according to the valence rules. If the bond is double outside the ring, the sulfur atom is not bonded to R ² or R ³ according to the valence rules.

The inventors have in fact discovered that the combination of the two additives phosphite and thiadiazole makes it possible to surprisingly improve the anti-corrosion properties as well as the durability of the lubricating composition comprising said combination of additives. The present invention thus makes it possible to propose an additive package and a lubricating composition making it possible to improve the anti-corrosion properties while having good durability, and this with a simple composition. In particular, the additive package and the lubricating composition according to the invention do not require the addition of zinc-based anti-wear or phenate, sulfonate and salicylate type detergent and do not require large quantities of phosphorus or sulfur.

Phosphite compound of formula (1)

The additive package according to the invention comprises one or more phosphite-type additives corresponding to formula (1):

[Chem 1]

GOLD

OH in which,

R and R ¹ represent, independently of one another, a hydrogen atom or a linear or branched, saturated or unsaturated hydrocarbon group, comprising from 1 to 24 carbon atoms, said hydrocarbon group optionally comprising one or more heteroatoms.

For the purposes of the present invention, the term “hydrocarbon group” means a chain comprising carbon and hydrogen atoms and optionally comprising one or more heteroatoms, such as oxygen or nitrogen atoms.

Advantageously, the phosphite compound of formula (1) does not comprise a sulfur atom.

According to one embodiment, R and R ¹ represent, independently of one another, a hydrogen atom or a linear or branched alkyl group, comprising from 1 to 24 carbon atoms, preferably from 1 to 12 carbon atoms, more preferably from 2 to 8 carbon atoms. Preferably, R and R ¹ represent a linear or branched alkyl group, of 1 to 24 carbon atoms, preferably of 1 to 12 carbon atoms, more preferably of 2 to 8 carbon atoms.

Preferably, R and R ¹ are identical and represent a linear or branched alkyl group, of 1 to 24 carbon atoms, preferably of 1 to 12 carbon atoms, more preferably of 2 to 8 carbon atoms.

For the purposes of the present invention, “alkyl” means a saturated group consisting of carbon and hydrogen atoms.

Particularly advantageously, the phosphite additive of formula (1) is dibutyl hydrogen phosphite.

The additive package may optionally comprise a mixture of compounds corresponding to formula (1).

According to one embodiment, the additive package comprises at least 0.5% by weight, preferably from 0.5 to 20% by weight, more preferably from 1 to 10% by weight, or even from 2 to 5% by weight, of phosphite compound(s) of formula (1), relative to the total weight of the additive package.

Thiadiazole compound

The additive package according to the invention comprises one or more thiadiazole additives corresponding to one of the formulas (2), (3), (4) or (5)

[Chem 2]

dans lesquelles : [Chem 3]

in which:

R ² and R ³ represent, independently of one another, a hydrogen atom or a linear or branched, saturated or unsaturated hydrocarbon group, comprising from 1 to 24 carbon atoms, said hydrocarbon group optionally comprising one or more heteroatoms.

The bond with the dotted line means that the bond can be double or single. If the bond is double, the nitrogen atom attached to this double bond is not bonded to a hydrogen atom according to the valence rules.

In particular, the compounds of formula (2), (3), (4) or (5) may correspond respectively to one of the formulas (2bis), (3bis), (4bis) or (5bis):

[Chem 3bis]

[Chem 2bis]

[Chem 3bis]

For example, the compound of formula (2) may be a compound of formula (8), formula (9), formula (10) or formula (11): [Chem 8]

[Chem 10]

Preferably, R ² and R ³ represent, independently of one another, a hydrogen atom, a linear or branched alkyl group comprising from 6 to 18 carbon atoms, a -SR' group where R' can be a linear or branched alkyl group comprising from 6 to 18 carbon atoms.

Preferably, R ² and R ³ are not both hydrogen in the thiadiazole compound of formula (2), (3), (4) and/or (5).

Preferably, the additive package according to the invention comprises at least one thiadiazole compound corresponding to formula (2).

The additive package may optionally comprise a mixture of thiadiazole compounds corresponding to one or more of formulas (2), (3), (4) or (5).

According to an advantageous embodiment, the package of additives according to the invention comprises a mixture of compounds corresponding to formula (2).

According to one embodiment, the additive package comprises at least 1% by weight of thiadiazole compound(s) of formula (2), (3), (4) and/or (5), preferably from 1 to 20% by weight, more preferably from 2 to 15% by weight, or even from 3 to 10% by weight, relative to the total weight of the additive package.

Preferably, the mass ratio between the quantity of phosphite compound(s) of formula (1) and the quantity of thiadiazole compound(s) of formula (2), (3), (4) and/or (5) ranges from 1/10 to 10/1, preferably from 1/5 to 5/1, more preferably from 1/2 to 2/1. According to a particularly advantageous embodiment, the package of additives according to the invention comprises at least one phosphite compound of formula (1) and at least one thiadiazole compound of formula (2), in which:

R and R ¹ represent, independently of one another, a linear or branched alkyl group, of 1 to 24 carbon atoms, preferably of 1 to 12 carbon atoms, more preferably of 2 to 8 carbon atoms; and/or

R ² and R ³ independently represent a hydrogen atom, a linear or branched alkyl group comprising from 6 to 18 carbon atoms, a -SR' group where R' can be a linear or branched alkyl group comprising from 6 to 18 carbon atoms.

The additive package advantageously comprises the combination of the phosphite and thiadiazole compounds as defined in the invention with at least one compound chosen from (i) a thiophosphate compound in particular of formula (6) or (ii) a phosphate compound in particular of formula (7).

Thiophosphate additive

According to one embodiment, the additive package further comprises at least one thiophosphate compound, preferably corresponding to formula (6):

dans laquelle : [Chem 6]

in which:

R ⁵ and R ⁶ represent, independently of one another, a hydrogen atom or a linear or branched, saturated or unsaturated hydrocarbon group, comprising from 1 to 24 carbon atoms, said hydrocarbon group optionally comprising one or more heteroatoms,

R ⁴ represents an OR ^4a group or an SR ^4a group where R ^4a represents a linear or branched, saturated or unsaturated hydrocarbon group, comprising from 1 to 24 carbon atoms, said hydrocarbon group optionally comprising one or more heteroatoms,

X represents a sulfur atom or an oxygen atom, it being understood that if X represents an oxygen atom then R ⁴ represents an SR ^4a group.

Advantageously, when the additive package comprises thiophosphate compounds, then the mass ratio between the quantity of thiadiazole compound(s) and thiophosphate compound(s) ranges from 1/5 to 2/1, preferably from 1/2 to 1.5/1. The inventors have in fact observed that the anti-corrosion properties were further improved when the lubricating composition comprises this mass ratio between the thiadiazole compound(s) and the thiophosphate compound(s).

Preferably, in formula (6):

- R ⁵ and R ⁶ represent, independently of one another, a hydrogen atom or a linear or branched alkyl group, comprising from 1 to 24 carbon atoms, preferably from 1 to 12 carbon atoms, more preferably from 2 to 8 carbon atoms, and/or

- X represents a sulfur atom, and/or

- R ⁴ represents an SR ^4a group where R ^4a represents an R ^4b COOH group where R ^4b represents a linear or branched alkyl group, comprising from 1 to 24 carbon atoms, preferably from 1 to 12 carbon atoms, more preferably from 2 to 8 carbon atoms.

The additive package may optionally include a mixture of thiophosphate compounds, or even a mixture of several compounds corresponding to formula (6).

According to one embodiment, the additive package comprises from 1 to 20% by weight, preferably from 2 to 15% by weight, preferably from 3 to 10% by weight, of thiophosphate compound(s), preferably corresponding to formula (6), relative to the total weight of the additive package. Phosphate additive

According to one embodiment, the additive package further comprises at least one phosphate compound, preferably corresponding to formula (7):

dans laquelle : [Chem 7]

in which:

R ⁷ and R ⁸ are chosen independently of one another from a hydrogen atom or linear or branched, saturated or unsaturated hydrocarbon groups comprising from 4 to 24 carbon atoms, at least one of the two radicals R ⁷ or R ⁸ being a linear or branched, saturated or unsaturated hydrocarbon group comprising from 4 to 24 carbon atoms.

In the context of the present invention, a phosphate compound is distinguished from a thiophosphate compound in particular in that it does not contain sulfur atoms.

Preferably, R ⁷ and R ⁸ are chosen independently of one another from a hydrogen atom or a linear or branched, saturated or unsaturated aliphatic group comprising from 4 to 24 carbon atoms, preferably from 8 to 20 carbon atoms.

The additive package may optionally include a mixture of phosphate compounds, or even a mixture of several compounds corresponding to formula (7).

According to one embodiment, the additive package comprises from 1 to 25% by weight, preferably from 2 to 20% by weight, preferably from 3 to 15% by weight, of phosphate compound(s), preferably corresponding to formula (7), relative to the total weight of the additive package.

Other ingredients in the additive package or lubricating composition

The additive package may optionally further comprise one or more base oils and/or one or more functional additives other than the phosphite additives, different from thiadiazole additives and different from thiophosphate additives and different from phosphate additives.

Among the functional additives other than phosphite additives, other than thiadiazole additives and other than (thio)phosphate additives, which can be added, mention may be made of dispersants, antioxidants, anticorrosion agents, antifoam agents, viscosity index improvers, and mixtures thereof.

Base oil

Preferably, the additive package according to the invention comprises at least one base oil having a kinematic viscosity at 100°C according to the ASTM D445 standard ranging from 1.5 to 35 cSt. Advantageously, the base oil(s) of the additive package according to the invention has(have) a kinematic viscosity at 100°C ranging from 1.5 to 35 cSt.

These base oils may be selected from base oils conventionally used in the field of lubricating oils, such as mineral, synthetic or natural, animal or vegetable oils or mixtures thereof. Typically, the base oil(s) are non-aqueous base oils.

It can be a mixture of several base oils, for example a mixture of two, three, or four base oils.

The base oils may in particular be oils of mineral or synthetic origin 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, de-alphatting, solvent dewaxing, hydrotreating, hydrocracking, hydroisomerization and hydrofinishing.

Blends of synthetic and mineral oils, which can be bio-sourced, can also be used.

There is generally no limitation on the use of different base oils to make the additive package and the lubricating composition according to the invention, except that they must have properties, in particular in terms of viscosity, viscosity index, or resistance to oxidation, suitable for use in transmissions, in particular for electric vehicles.

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

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

Advantageously, the base oil or oils of the additive package and/or of the lubricating composition according to the invention may be chosen from base oils of group II or III.

According to an alternative embodiment, the base oil or oils of the additive package and/or of the composition according to the invention are chosen from polyalphaolefins (PAO), polyalkylene glycol (PAG) and esters of carboxylic acids and alcohols.

The additive package may comprise from 1 to 80% by weight of base oil(s), preferably from 2 to 50% by weight of base oil(s), more preferably from 5 to 30% by weight of base oil(s).

Dispersing

According to one embodiment, the additive package according to the invention further comprises at least one dispersant, preferably a borated dispersant, more preferably a borated dispersant chosen from borated succinimides, more preferably from borated polyisobutene succinimides. Typically, the dispersant will ensure the maintenance in suspension and the evacuation of insoluble solid contaminants constituted by the secondary oxidation products which form when the lubricating composition is in service.

According to this embodiment, preferably, the additive package comprises from 5 to 80% by weight of dispersant(s), preferably from 10 to 70% by weight, more preferably from 20 to 60% by weight, of dispersant(s), relative to the total weight of the additive package.

The additive package and/or the lubricating composition according to the invention may contain all types of dispersants known to those skilled in the art.

Antioxidant

The additive package according to the invention may comprise at least one antioxidant additive. The antioxidant additive generally helps to delay the degradation of the composition in service. This degradation can notably result in the formation of deposits, the presence of sludge or an increase in the viscosity of the composition.

Antioxidant additives act in particular as radical inhibitors or hydroperoxide destroyers. Among the commonly used antioxidant additives, mention may be made of phenolic antioxidant additives and amine antioxidant additives. Phenolic antioxidant additives may be ash-free or in the form of neutral or basic metal salts. The antioxidant additives may 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 C1-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 vicinal carbon of the carbon carrying the alcohol function is substituted by at least one C1-C10 alkyl group, preferably a C1-C6 alkyl group, preferably a C4 alkyl group, preferably by the tert-butyl group.

Amino compounds are another class of antioxidant additives that can be used, optionally in combination with phenolic antioxidant additives. Examples of amine compounds are aromatic amines, for example aromatic amines of the formula NR ¹⁰ R ⁿ R ¹² in which R ¹⁰ represents an aliphatic group or an aromatic group, optionally substituted, R ¹¹ represents an aromatic group, optionally substituted, R ¹² represents a hydrogen atom, an alkyl group, an aryl group or a group of the formula R ¹³ S(O) _Z R ¹⁴ in which R ¹³ represents an alkylene group or an alkenylene group, R ¹⁴ represents an alkyl group, an alkenyl group or an aryl group and z represents 0, 1 or 2.

The additive package and/or the lubricating composition according to the invention may contain all types of antioxidant additives known to those skilled in the art.

According to this embodiment, preferably, the additive package comprises from 1 to 40% by weight of antioxidant(s), preferably from 2 to 30% by weight, more preferably from 5 to 25% by weight, of antioxidant(s), relative to the total weight of the additive package. These other functional additives (different from phosphite additives, different from thiadiazole additives and different from thiophosphate additives) can be added to the lubricating composition according to the invention via the additive package according to the invention or directly individually to the lubricating composition according to the invention.

According to one embodiment, the additive package comprises:

- at least one phosphite compound of formula (1), and

- at least one thiadiazole compound corresponding to one of the formulas (2), (3), (4) or (5), - at least one borated dispersant,

[Chem 1]

dans lesquelles : [Chem 5]

in which:

R and R ¹ represent, independently of each other, a hydrogen atom or a linear or branched, saturated or unsaturated hydrocarbon group comprising from 1 to 24 carbon atoms, said hydrocarbon group optionally comprising one or more heteroatoms, R ² and R ³ represent, independently of each other, a hydrogen atom or a linear or branched, saturated or unsaturated hydrocarbon group comprising from 1 to 24 carbon atoms, said hydrocarbon group optionally comprising one or more heteroatoms, said additive package further comprising at least one compound chosen from (i) a thiophosphate compound, (ii) a phosphate compound corresponding to formula (7), and (iii) their mixture,

dans laquelle : [Chem 7]

in which:

R ⁷ and R ⁸ are chosen independently of one another from a hydrogen atom or linear or branched, saturated or unsaturated hydrocarbon groups comprising from 4 to 24 carbon atoms, at least one of the two radicals R ⁷ or R ⁸ being a linear or branched, saturated or unsaturated hydrocarbon group comprising from 4 to 24 carbon atoms.

According to this embodiment, advantageously, when one or more thiophosphate compounds are present, then the mass ratio between the thiadiazole compound(s) and the thiophosphate compound(s) ranges from 1/5 to 2/1, preferably from 1/2 to 1.5/1. According to one embodiment of the invention, the additive package comprises:

- at least 0.5% by weight, preferably from 0.5 to 20% by weight, more preferably from 1 to 10% by weight, or even from 2 to 5% by weight, of phosphite compound(s) of formula (1),

- at least 1% by weight, preferably from 1 to 20% by weight, more preferably from 2 to 15% by weight, or even from 3 to 10% by weight, of thiadiazole compound(s), preferably corresponding to formula (2),

- optionally from 1 to 20% by weight, preferably from 2 to 15% by weight, of compound(s) chosen from (i) a thiophosphate compound, preferably corresponding to formula (6), (ii) a phosphate compound, preferably corresponding to formula (7), and (iii) their mixture,

- optionally up to 100% by weight of base oil(s) and/or additive(s) other than the phosphite, thiadiazole, phosphate and thiophosphate additives, it being understood that if the additive package further comprises a thiophosphate compound, then the mass ratio between the thiadiazole compound(s) and the thiophosphate compound(s) ranges from 1/5 to 2/1, relative to the total weight of the additive package.

According to one embodiment of the invention, the additive package comprises:

- from 2 to 5% by weight of phosphite compound(s) of formula (1),

- from 3 to 10% by weight of thiadiazole compound(s), preferably corresponding to formula (2),

- optionally from 2 to 15% by weight of compound(s) chosen from (i) a thiophosphate compound, preferably corresponding to formula (6), (ii) a phosphate compound, preferably corresponding to formula (7), and (iii) their mixture,

- optionally up to 100% by weight of base oil(s) and/or additive(s) other than the phosphite, thiadiazole, phosphate and thiophosphate additives, it being understood that if the additive package further comprises a thiophosphate compound, then the mass ratio between the thiadiazole compound(s) and the thiophosphate compound(s) ranges from 1/5 to 2/1, relative to the total weight of the additive package.

According to one embodiment of the invention, the additive package comprises:

- at least 0.5% by weight, preferably from 0.5 to 20% by weight, more preferably from 1 to 10% by weight, or even from 2 to 5% by weight, of phosphite compound(s) of formula (1), in in which R and R ¹ represent a linear or branched alkyl group, of 1 to 24 carbon atoms, preferably of 1 to 12 carbon atoms, more preferably of 2 to 8 carbon atoms,

- at least 1% by weight, preferably from 1 to 20% by weight, more preferably from 2 to 15% by weight, or even from 3 to 10% by weight, of thiadiazole compound(s), preferably corresponding to formula (2),

- optionally from 1 to 20% by weight, preferably from 2 to 15% by weight, of compound(s) chosen from (i) a thiophosphate compound, preferably corresponding to formula (6), (ii) a phosphate compound, preferably corresponding to formula (7), and (iii) their mixture,

- possibly up to 100% by weight of base oil(s) and/or additive(s) other than phosphite, thiadiazole, phosphate and thiophosphate additives, relative to the total weight of the additive package.

According to one embodiment of the invention, the additive package comprises:

- at least 0.5% by weight, preferably from 0.5 to 20% by weight, more preferably from 1 to 10% by weight, or even from 2 to 5% by weight, of phosphite compound(s) of formula (1),

- at least 1% by weight, preferably from 1 to 20% by weight, more preferably from 2 to 15% by weight, or even from 3 to 10% by weight, of thiadiazole compound(s), preferably corresponding to formula (2),

- optionally from 1 to 20% by weight, preferably from 2 to 15% by weight, of compound(s) chosen from (i) a thiophosphate compound, preferably corresponding to formula (6), (ii) a phosphate compound, preferably corresponding to formula (7), and (iii) their mixture,

- optionally from 5 to 80% by weight of dispersant(s), preferably from 10 to 70% by weight, more preferably from 20 to 60% by weight, of dispersant(s), preferably at least one dispersant is a borated dispersant,

- possibly up to 100% by weight of base oil(s) and/or additive(s) other than the phosphite, thiadiazole, thiophosphate, phosphate and dispersant additives, relative to the total weight of the additive package.

According to one embodiment of the invention, the additive package comprises:

- from 2 to 5% by weight of phosphite compound(s) of formula (1),

- from 3 to 10% by weight of thiadiazole compound(s), preferably corresponding to formula (2), - from 2 to 15% by weight of compound(s) chosen from (i) a thiophosphate compound, preferably corresponding to formula (6), (ii) a phosphate compound, preferably corresponding to formula (7), and (iii) their mixture,

- optionally from 20 to 60% by weight of dispersant(s), preferably at least one dispersant is a borated dispersant,

- possibly up to 100% by weight of base oil(s) and/or additive(s) other than the phosphite, thiadiazole, thiophosphate, phosphate and dispersant additives, relative to the total weight of the additive package.

According to one embodiment of the invention, the additive package comprises:

- at least 0.5% by weight, preferably from 0.5 to 20% by weight, more preferably from 1 to 10% by weight, or even from 2 to 5% by weight, of phosphite compound(s) of formula (1),

- at least 1% by weight, preferably from 1 to 20% by weight, more preferably from 2 to 15% by weight, or even from 3 to 10% by weight, of thiadiazole compound(s), preferably corresponding to formula (2),

- from 1 to 20% by weight, preferably from 2 to 15% by weight, of compound(s) chosen from (i) a thiophosphate compound corresponding to formula (6) in which R ⁴ represents an SR ^4a group where R ^4a represents an R ^4b COOH group where R ^4b represents a linear or branched alkyl group, comprising from 1 to 24 carbon atoms, preferably from 1 to 12 carbon atoms, more preferably from 2 to 8 carbon atoms, (ii) a phosphate compound, preferably corresponding to formula (7), and (iii) their mixture,

- optionally from 5 to 80% by weight of dispersant(s), preferably from 10 to 70% by weight, more preferably from 20 to 60% by weight, of dispersant(s), preferably at least one dispersant is a borated dispersant,

- possibly up to 100% by weight of base oil(s) and/or additive(s) other than the phosphite, thiadiazole, thiophosphate, phosphate and dispersant additives, relative to the total weight of the additive package.

This embodiment is particularly advantageous when the additive package is implemented in a lubricating composition itself implemented in an electric vehicle.

According to one embodiment of the invention, the additive package comprises: - from 2 to 5% by weight of phosphite compound(s) of formula (1),

- from 3 to 10% by weight of thiadiazole compound(s), preferably corresponding to formula (2),

- from 2 to 15% by weight of compound(s) chosen from (i) a thiophosphate compound, preferably corresponding to formula (6), (ii) a phosphate compound, preferably corresponding to formula (7), and (iii) their mixture,

- from 20 to 60% by weight of dispersant(s), preferably at least one dispersant is a borated dispersant,

- possibly up to 100% by weight of base oil(s) and/or additive(s) other than the phosphite, thiadiazole, thiophosphate, phosphate and dispersant additives, relative to the total weight of the additive package.

According to one embodiment of the invention, the additive package comprises:

- from 2 to 5% by weight of phosphite compound(s) of formula (1),

- from 3 to 10% by weight of thiadiazole compound(s), preferably corresponding to formula (2),

- from 2 to 15% by weight of compound(s) chosen from (i) a thiophosphate compound, preferably corresponding to formula (6), (ii) a phosphate compound corresponding to formula (7), and (iii) their mixture,

- from 20 to 60% by weight of dispersant(s), preferably at least one dispersant is a borated dispersant,

- possibly up to 100% by weight of base oil(s) and/or additive(s) other than the phosphite, thiadiazole, thiophosphate, phosphate and dispersant additives, relative to the total weight of the additive package.

According to one embodiment of the invention, the additive package comprises:

- at least 0.5% by weight, preferably from 0.5 to 20% by weight, more preferably from 1 to 10% by weight, or even from 2 to 5% by weight, of phosphite compound(s) of formula (1),

- at least 1% by weight, preferably from 1 to 20% by weight, more preferably from 2 to 15% by weight, or even from 3 to 10% by weight, of thiadiazole compound(s), preferably corresponding to formula (2),

- optionally from 1 to 20% by weight, preferably from 2 to 15% by weight, of compound(s) chosen from (i) a thiophosphate compound, preferably corresponding to formula (6), (ii) a phosphate compound, preferably corresponding to formula (7), and (iii) their mixture, - optionally from 5 to 80% by weight of dispersant(s), preferably from 10 to 70% by weight, more preferably from 20 to 60% by weight, of dispersant(s), preferably at least one dispersant is a borated dispersant,

- possibly up to 100% by weight of base oil(s) and/or additive(s) other than the phosphite, thiadiazole, thiophosphate, phosphate and dispersant additives, relative to the total weight of the additive package.

According to one embodiment of the invention, the additive package comprises:

- at least 0.5% by weight, preferably from 0.5 to 20% by weight, more preferably from 1 to 10% by weight, or even from 2 to 5% by weight, of phosphite compound(s) of formula (1) where R and R ¹ represent, independently of one another, a hydrogen atom or a linear or branched alkyl group, comprising from 1 to 24 carbon atoms, preferably from 1 to 12 carbon atoms, more preferably from 2 to 8 carbon atoms,

- at least 1% by weight, preferably from 1 to 20% by weight, more preferably from 2 to 15% by weight, or even from 3 to 10% by weight, of thiadiazole compound(s), at least one of which corresponds to formula (2),

- from 1 to 20% by weight, preferably from 2 to 15% by weight, preferably from 3 to 10% by weight, of compound(s) chosen from (i) a thiophosphate compound corresponding to formula (6), (ii) a phosphate compound corresponding to formula (7), and (iii) their mixture, preferably chosen from (i) a thiophosphate compound corresponding to formula (6),

- optionally from 5 to 80% by weight of dispersant(s), preferably from 10 to 70% by weight, more preferably from 20 to 60% by weight, of dispersant(s), preferably at least one dispersant is a borated dispersant,

- optionally up to 100% by weight of base oil(s) and/or additive(s) other than the phosphite, thiadiazole, thiophosphate, phosphate and dispersant additives, relative to the total weight of the additive package, it being understood that if the additive package comprises a thiophosphate compound, then the mass ratio between the thiadiazole compound and the thiophosphate compound ranges from 1/5 to 2/1, preferably from 1/2 to 1.5/1.

Preferably, the additive package according to the invention comprises from 4000 to 30000 ppm by weight of sulfur, preferably from 5000 to 15000 ppm by weight of sulfur. Preferably, the additive package according to the invention comprises from 6000 to 40000 ppm by weight of phosphorus, preferably from 10000 to 30000 ppm by weight of phosphorus.

Preferably, the additive package according to the invention does not comprise anti-wear additives comprising zinc.

Preferably, the additive package according to the invention does not comprise sulfonate detergent, phenate detergent or salicylate detergent.

Preferably, the package of additives according to the invention does not comprise phosphorus compounds other than the compound(s) corresponding to formula (1) and formula (7).

The phosphite compounds of formula (1) and the thiadiazole compound(s) of formula (2), (3), (4) and/or (5) provide sulfur and/or phosphorus to the additive package according to the invention. Preferably, the phosphite compounds of formula (1) provide phosphorus but do not provide sulfur and the thiadiazole compounds of formula (2), (3), (4) and/or (5) provide sulfur but do not provide phosphorus.

Advantageously, the mass ratio between the sulfur content and the phosphorus content provided by the phosphite compound(s) of formula (1) and the thiadiazole compound(s) ranges from 1/1 to 3.5/1. Preferably, the mass ratio between the sulfur content provided by the thiadiazole compounds of formula (2), (3), (4) and/or (5) and the phosphorus content provided by the phosphite compounds of formula (1) ranges from 1/1 to 3.5/1.

The invention relates to a lubricating composition obtained by mixing the additive package according to the invention with at least one base oil and optionally one or more functional additives generally different from the additives of the additive package.

The base oil(s) used to obtain the lubricating composition according to the invention may be identical to or different from the base oil(s) possibly present in the additive package.

Thus, the present invention relates to a lubricating composition comprising:

- at least 60% by weight of base oil(s), relative to the total weight of the lubricating composition,

- at least one phosphite compound of formula (1), and - at least one thiadiazole compound corresponding to one of the formulas (2), (3), (4) or (5).

The compounds of formula (1), (2), (3), (4) and (5) are as defined within the additive package and preferably exhibit one or more of the advantageous characteristics defined within the additive package.

The base oil(s) as defined in the additive package may exhibit one or more of the beneficial characteristics defined in the additive package.

According to one embodiment, the lubricating composition according to the invention comprises, or even consists of:

- from 80 to 99.5% by weight, preferably from 85 to 99% by weight, of base oil(s),

- from 0.5 to 20% by weight, preferably from 1 to 15% by weight, of the additive package according to the invention, relative to the total weight of the lubricating composition.

According to one embodiment, the lubricating composition according to the invention further comprises (i) at least one thiophosphate compound, preferably corresponding to formula (6), and/or (ii) at least one phosphate compound, preferably corresponding to formula (7).

The compound of formula (6) is as defined within the additive package and preferably exhibits one or more of the advantageous characteristics defined within the additive package.

When the lubricating composition comprises thiophosphate compounds, then the mass ratio between the quantity of thiadiazole compound(s) and thiophosphate compound(s) ranges from 1/5 to 2/1, preferably from 1/2 to 1.5/1.

The compound of formula (7) is as defined within the scope of the additive package and preferably exhibits one or more of the advantageous characteristics defined within the scope of the additive package. Preferably, the lubricating composition according to the invention comprises, or even consists of:

- from 70 to 99% by weight, preferably from 85 to 99% by weight, of base oil(s),

- from 0.01 to 5% by weight, preferably from 0.05 to 1% by weight, of phosphite compound(s),

- from 0.01 to 5% by weight, preferably from 0.05 to 1% by weight, of thiadiazole compound(s),

- optionally from 0.01 to 5% by weight, preferably from 0.05 to 1% by weight, of compound(s) chosen from (i) a thiophosphate compound, preferably corresponding to formula (6), (ii) a phosphate compound, preferably corresponding to formula (7), and (iii) their mixture,

- optionally up to 100% by weight of additive(s) other than the phosphite, thiadiazole and thiophosphate additives, relative to the total weight of the lubricating composition wherein if the lubricating composition comprises (i) a thiophosphate compound, then the mass ratio between the thiadiazole compound and the thiophosphate compound ranges from 1/5 to 2/1, preferably from 1/2 to 1.5/1.

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

- from 70 to 99% by weight, preferably from 85 to 99% by weight, of base oil(s),

- from 0.01 to 5% by weight, preferably from 0.05 to 1% by weight, of phosphite compound(s) of formula (1) in which R and R ¹ represent a linear or branched alkyl group, from 1 to 24 carbon atoms, preferably from 1 to 12 carbon atoms, more preferably from 2 to 8 carbon atoms,

- from 0.01 to 5% by weight, preferably from 0.05 to 1% by weight, of thiadiazole compound(s),

- optionally from 0.01 to 5% by weight, preferably from 0.05 to 1% by weight, of compound(s) chosen from (i) a thiophosphate compound, preferably corresponding to formula (6), (ii) a phosphate compound, preferably corresponding to formula (7), and (iii) their mixture,

- optionally up to 100% by weight of additive(s) other than the phosphite, thiadiazole and thiophosphate additives, relative to the total weight of the lubricating composition, wherein if the lubricating composition comprises (i) a thiophosphate compound, then the mass ratio between the thiadiazole compound and the thiophosphate compound ranges from 1/5 to 2/1, preferably from 1/2 to 1.5/1. Preferably, the lubricating composition according to the invention comprises, or even consists of:

- from 70 to 99% by weight, preferably from 85 to 99% by weight, of base oil(s),

- from 0.01 to 5% by weight, preferably from 0.05 to 1% by weight, of phosphite compound(s),

- from 0.01 to 5% by weight, preferably from 0.05 to 1% by weight, of thiadiazole compound(s),

- from 0.01 to 5% by weight, preferably from 0.05 to 1% by weight, of compound(s) chosen from (i) a thiophosphate compound, preferably corresponding to formula (6), (ii) a phosphate compound, preferably corresponding to formula (7), and (iii) their mixture,

- optionally up to 100% by weight of additive(s) other than the phosphite, thiadiazole, phosphate and thiophosphate additives, relative to the total weight of the lubricating composition, wherein if the lubricating composition comprises (i) a thiophosphate compound, then the mass ratio between the thiadiazole compound and the thiophosphate compound ranges from 1/5 to 2/1, preferably from 1/2 to 1.5/1.

According to one embodiment, the lubricating composition according to the invention further comprises at least one dispersant, preferably a borated dispersant, more preferably a borated dispersant chosen from borated succinimides, more preferably from borated polyisobutene succinimides.

According to one embodiment, the lubricating composition according to the invention comprises, or even consists of:

- from 70 to 99% by weight, preferably from 85 to 99% by weight, of base oil(s),

- from 0.01 to 5% by weight, preferably from 0.05 to 1% by weight, of phosphite compound(s),

- from 0.01 to 5% by weight, preferably from 0.05 to 1% by weight, of thiadiazole compound(s),

- optionally from 0.01 to 5% by weight, preferably from 0.05 to 1% by weight, of compound(s) chosen from (i) a thiophosphate compound, preferably corresponding to formula (6), (ii) a phosphate compound, preferably corresponding to formula (7), and (iii) their mixture,

- optionally from 1 to 20% by weight of dispersant(s), preferably from 1 to 15% by weight, more preferably from 2 to 10% by weight, of dispersant(s), - optionally up to 100% by weight of base oil(s) and/or additive(s) other than the phosphite, thiadiazole, thiophosphate, phosphate and dispersant additives, relative to the total weight of the lubricating composition, wherein if the lubricating composition comprises (i) a thiophosphate compound, then the mass ratio between the thiadiazole compound and the thiophosphate compound ranges from 1/5 to 2/1, preferably from 1/2 to 1.5/1.

According to one embodiment, the lubricating composition according to the invention further comprises at least one antioxidant. The lubricating composition according to the invention may comprise from 0.2 to 2% by weight, preferably from 0.3 to 1% by weight, of antioxidant additive(s), relative to the total weight of the composition.

The lubricating composition according to the invention may also comprise at least one viscosity index improving additive (VI improver). Examples of VI improvers include polymethacrylates, polyisobutenes or fatty acid esters. The viscosity index improving additive may represent from 0.01 to 10% by weight, or even from 0.05 to 5% by weight, of the total weight of the lubricating composition.

The lubricating composition according to the invention may further comprise at least one antifoaming agent. The antifoaming agent may be chosen from silicones. The lubricating composition according to the invention may comprise from 0.01 to 5% by weight, preferably from 0.1 to 1.5% by weight or even from 0.1 to 2% by weight of antifoaming agent, relative to the total weight of the composition.

According to one embodiment, the lubricating composition according to the invention comprises, or even consists of:

- from 70 to 99% by weight, preferably from 85 to 99% by weight, of base oil(s),

- from 0.01 to 5% by weight, preferably from 0.05 to 1% by weight, of phosphite compound(s),

- from 0.01 to 5% by weight, preferably from 0.05 to 1% by weight, of thiadiazole compound(s),

- from 0.01 to 5% by weight, preferably from 0.05 to 1% by weight, of compound(s) chosen from (i) a thiophosphate compound, preferably corresponding to formula (6), (ii) a phosphate compound, preferably corresponding to formula (7), and (iii) their mixture,

- from 1 to 15% by weight, more preferably from 2 to 10% by weight, of dispersant(s), - optionally from 0.2 to 2% by weight, preferably from 0.3 to 1% by weight, of antioxidant additive(s),

- optionally from 0.01 to 5% by weight, preferably from 0.1 to 1.5% by weight, of antifoam additive(s),

- optionally from 0.01 to 10% by weight, or even from 0.05 to 5% by weight, of viscosity index improver, relative to the total weight of the lubricating composition, wherein if the lubricating composition comprises (i) a thiophosphate compound, then the mass ratio between the thiadiazole compound and the thiophosphate compound ranges from 1/5 to 2/1, preferably from 1/2 to 1.5/1.

According to one embodiment, the lubricating composition according to the invention comprises, or even consists of:

- from 70 to 99% by weight, preferably from 85 to 99% by weight, of base oil(s),

- from 0.01 to 5% by weight, preferably from 0.05 to 1% by weight, of phosphite compound(s),

- from 0.01 to 5% by weight, preferably from 0.05 to 1% by weight, of thiadiazole compound(s),

- from 0.01 to 5% by weight, preferably from 0.05 to 1% by weight, of compound(s) chosen from (i) a thiophosphate compound corresponding to formula (6), (ii) a phosphate compound corresponding to formula (7), and (iii) their mixture, preferably chosen from (i) a thiophosphate compound corresponding to formula (6),

- from 1 to 15% by weight, more preferably from 2 to 10% by weight, of dispersant(s),

- optionally from 0.2 to 2% by weight, preferably from 0.3 to 1% by weight, of antioxidant additive(s),

- optionally from 0.01 to 5% by weight, preferably from 0.1 to 1.5% by weight, of antifoam additive(s),

- optionally from 0.01 to 10% by weight, or even from 0.05 to 5% by weight, of viscosity index improver, relative to the total weight of the lubricating composition, wherein if the lubricating composition comprises (i) a thiophosphate compound, then the mass ratio between the thiadiazole compound and the thiophosphate compound ranges from 1/5 to 2/1, preferably from 1/2 to 1.5/1. Preferably, the thiophosphate compound(s) provides from 100 to 1000 ppm by weight of sulfur to the lubricating composition according to the invention, preferably from 150 to 700 ppm by weight.

Preferably, the thiadiazole compound(s) of formula (2), (3), (4) and/or (5) provides from 100 to 3000 ppm by weight of sulfur to the lubricating composition according to the invention, preferably from 200 to 2000 ppm by weight.

Preferably, the phosphite compound(s) of formula (1) provides from 100 to 1000 ppm by weight of phosphorus to the lubricating composition according to the invention, preferably from 120 to 500 ppm by weight.

Preferably, the lubricating composition according to the invention comprises from 200 to 4000 ppm by weight of sulfur, preferably from 350 to 2700 ppm by weight of sulfur.

Preferably, the lubricating composition according to the invention comprises from 100 to 1200 ppm by weight of phosphorus, preferably from 120 to 1000 ppm by weight of phosphorus.

Preferably, the lubricating composition according to the invention does not comprise anti-wear additives comprising zinc.

Preferably, the lubricating composition according to the invention does not comprise sulfonate detergent, phenate detergent or salicylate detergent.

Preferably, the lubricating composition according to the invention does not comprise phosphorus compounds other than the compound(s) corresponding to formula (1) and formula (7).

Advantageously, the lubricating composition according to the invention has a kinematic viscosity, measured at 40°C according to the ASTM D445 standard, ranging from 5 to 300 mm ² /s, preferably from 10 to 30 mm ² /s, more preferably from 15 to 25 mm ² /s.

Advantageously, the lubricating composition according to the invention has a kinematic viscosity, measured at 100°C according to the ASTM D445 standard, ranging from 1 to 20 mm ² /s, preferably from 1.5 to 15 mm ² /s, more preferably from 2 to 10 mm ² /s.

The present invention also relates to the use of the additive package according to the invention for formulating a lubricating composition intended to lubricate the motor vehicle transmissions, particularly transmission gears. Transmissions can be manual or automatic transmissions.

The additive package as defined in the present invention makes it possible to improve the anti-corrosion properties, in particular with respect to copper, of a lubricating composition comprising said additive package.

The additive package as defined in the present invention also makes it possible to improve the durability of a lubricating composition comprising said additive package.

Indeed, the combination of phosphite additives of formula (1) with thiadiazole additives of formula (2), (3), (4), and/or (5) makes it possible to surprisingly improve the anti-corrosion properties and the durability properties when the lubricating composition is used in transmissions.

The present invention also relates to the use of the lubricating composition according to the invention for lubricating the transmissions of motor vehicles, in particular the gears of the transmissions. The transmissions may be manual or automatic transmissions.

Preferably, the lubricating composition according to the invention is used to reduce the wear of a mechanical part of a motor vehicle transmission, in particular of a motor vehicle gear. Thus, according to this embodiment, the lubricating composition according to the invention makes it possible to reduce the wear of the transmission gears.

Preferably, the lubricating composition according to the invention is used to reduce flaking of a mechanical part of a motor vehicle transmission, in particular of a motor vehicle gear.

According to an advantageous embodiment, the lubricating composition according to the invention is used to both reduce wear and reduce flaking of a mechanical part of a motor vehicle transmission, in particular of a motor vehicle gear.

Preferably, the lubricating composition according to the invention is used in electric vehicles. The invention also relates, according to another of its aspects, to a method for lubricating at least one part of a transmission of a motor vehicle, in particular a gear of a motor vehicle, comprising at least one step of bringing at least said part into contact with a lubricating composition according to the invention.

The invention also relates, according to another of its aspects, to a method for improving the anti-corrosion properties of a lubricating composition, said method comprising a step of mixing at least one phosphite additive of formula (1) as defined in the present invention, with at least one thiadiazole additive as defined in the invention, preferably said additives are further mixed with a thiophosphate additive.

All of the characteristics and preferences described for the lubricating composition according to the invention as well as for its uses also apply to these processes.

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 for illustrative and non-limiting purposes of the invention.

Examples

Example 1: Preparation of additive packages

The additive packages were prepared by mixing the ingredients at a temperature of approximately 40°C, according to methods well known to those skilled in the art.

Table 2 shows the weight proportions of the ingredients in the tested additive packages.

[Table 2]

In which:

- the phosphite compound is dibutyl hydrogen phosphite,

- the thiadiazole compound comprises a mixture of thiadiazole compound(s) corresponding to formula (2) in which R ² and R ³ independently of each other represent a hydrogen atom, a linear or branched alkyl group comprising from 6 to 18 carbon atoms, a -SR' group where R' may be a linear or branched alkyl group comprising from 6 to 18 carbon atoms, it being understood that R ² and R ³ are not both a hydrogen atom in each of the thiadiazole compounds,

- the thiophosphate compound corresponds to formula (6) in which X is a sulfur atom; R ⁵ and R ⁶ represent, independently of one another, a hydrogen atom or a linear or branched alkyl group, comprising from 2 to 8 carbon atoms; R ⁴ represents an SR ^4a group where R ^4a represents an R ^4b COOH group where R ^4b represents a linear or branched alkyl group, comprising from 2 to 8 carbon atoms;

- the phosphate compound is an acid phosphate corresponding to formula (7) in which R ⁷ and R ⁸ are chosen independently of one another from a hydrogen atom or a linear or branched, saturated or unsaturated aliphatic group, comprising from 8 to 20 carbon atoms,

- the dispersing compound is a boronated PIB SI,

- the anticorrosion is a triazole derivative,

- the base oil is a group III base oil having a viscosity at 100°C of approximately 4 cSt. Example 2: Preparation of lubricating compositions

Lubricating compositions were prepared by mixing an additive package defined in Example 1 with a base oil and additives at a temperature of approximately 40°C, according to methods well known to those skilled in the art.

Table 3 shows the proportions (%) by weight of the ingredients of the lubricating compositions tested as well as the nature of the additive package used.

[Table 3]

Wherein the additives are selected from an antifoam and a viscosity index improver.

The elemental contents of phosphorus and sulfur were determined by inductively coupled plasma (ICP) spectrometry and are also shown in Table 3 in ppm by weight.

The lubricating compositions tested have a viscosity at 100°C of approximately 4.5 cSt measured according to ASTM D445.

Example 3: Studies of the performance of lubricating compositions

The anticorrosion properties of the lubricating compositions described in Table 3 were measured according to ASTM DI 30 modified as follows:

- Lubricating composition temperature of 150°C,

- Trial period of 168 hours,

- Weighing of the copper blade before and after testing, - ICP measurement of the copper content in the lubricating composition at the end of the test.

These operating conditions correspond to the more significant constraints placed on lubricating compositions in electric vehicle applications.

The difference in mass before and after testing (Amasse) is shown in Table 4.

[Table 4]

The compositions according to the invention also exhibit a very low difference in mass of the copper blade, demonstrating excellent anti-corrosion properties. Compositions C11 to C14 also exhibit better anti-corrosion properties than composition C15 exhibiting a mass ratio between the thiadiazole compound(s) and the thiophosphate compound(s) of 3/1.

Furthermore, the compositions according to the invention exhibit very good load-carrying capacity. In particular, compositions C11 to C15 showed values of at least 7 in an FZG A10/16.6R/90 test. These load-carrying capacity values (FZG) demonstrate the very good durability of the lubricating composition, particularly for use in transmissions.

The additive package as defined in the present invention makes it possible to improve the performance of the lubricating composition. More particularly, a lubricating composition according to the invention comprising an additive package according to the invention has improved anti-corrosion and durability properties.

Claims

Claims 1. Additive package including: - at least one phosphite compound of formula (1), and - at least one thiadiazole compound corresponding to one of formulas (2), (3), (4) or (5), [Chem 1]

in which: R and R ¹ represent, independently of one another, a hydrogen atom or a linear or branched, saturated or unsaturated hydrocarbon group, comprising from 1 to 24 carbon atoms, said hydrocarbon group optionally comprising one or more heteroatoms, R ² and R ³ represent, independently of one another, a hydrogen atom or a linear or branched, saturated or unsaturated hydrocarbon group, comprising from 1 to 24 carbon atoms, said hydrocarbon group optionally comprising one or more heteroatoms. 2. Additive package according to claim 1, wherein the mass ratio between the phosphite compound of formula (1) and the thiadiazole compound ranges from 1/10 to 10/1, preferably from 1/5 to 5/1, more preferably from 1/2 to 2/1. 3. An additive package according to claim 1 or 2, further comprising: - at least one borated dispersant, and - at least one compound chosen from (i) a thiophosphate compound, (ii) a phosphate compound corresponding to formula (7), and (iii) their mixture, [Chem 7]

in which: R ⁷ and R ⁸ are chosen independently of each other from a hydrogen atom or linear or branched, saturated or unsaturated hydrocarbon groups comprising from 4 to 24 carbon atoms, at least one of the two radicals R ⁷ or R ⁸ being a linear or branched, saturated or unsaturated hydrocarbon group comprising from 4 to 24 carbon atoms, it being understood that if one or more thiophosphate compounds are present, then preferably, the mass ratio between the thiadiazole compound(s) and the thiophosphate compound(s) ranges from 1/5 to 2/1, preferably from 1/2 to 1.5/1. 4. Additive package according to any one of claims 1 to 3, further comprising at least one dispersant, preferably a borated dispersant, more preferably a borated dispersant chosen from borated succinimides, more preferably from borated polyisobutene succinimides, said at least one dispersant preferably representing from 10 to 70% by weight, more preferably from 20 to 60% by weight, of dispersant(s), relative to the total weight of the additive package. 5. Additive package according to any one of claims 1 to 4, in which the mass ratio between the sulfur content and the phosphorus content provided by the phosphite compound(s) of formula (1) and the thiadiazole compound(s) ranges from 1/1 to 3.5/1. 6. Additive package according to any one of claims 1 to 5, wherein: - R and R ¹ represent, independently of one another, a hydrogen atom or a linear or branched alkyl group, comprising from 1 to 24 carbon atoms, preferably from 1 to 12 carbon atoms, more preferably from 2 to 8 carbon atoms, preferably R and R ¹ represent a linear or branched alkyl group, from 1 to 24 carbon atoms, preferably from 1 to 12 carbon atoms, more preferably from 2 to 8 carbon atoms, and/or - said at least one thiadiazole compound corresponds to formula (2), in which R ² and R ³ independently of each other represent a hydrogen atom, a linear or branched alkyl group comprising from 6 to 18 carbon atoms, a -SR' group where R' can be a linear or branched alkyl group comprising from 6 to 18 carbon atoms. 7. Additive package according to any one of claims 1 to 6, further comprising at least one thiophosphate compound, the mass ratio between the thiadiazole compound(s) and the thiophosphate compound(s) ranging from 1/5 to 2/1, preferably from 1/2 to 1.5/1, preferably said at least one thiophosphate compound corresponding to formula (6): [Chem 6]

in which: R ⁵ and R ⁶ represent, independently of one another, a hydrogen atom or a linear or branched, saturated or unsaturated hydrocarbon group, comprising from 1 to 24 carbon atoms, said hydrocarbon group optionally comprising one or more heteroatoms, R ⁴ represents an OR ^4a group or an SR ^4a group where R ^4a represents a linear or branched, saturated or unsaturated hydrocarbon group, comprising from 1 to 24 carbon atoms, said hydrocarbon group optionally comprising one or more heteroatoms, X represents a sulfur atom or an oxygen atom, it being understood that if X represents an oxygen atom then R ⁴ represents an SR ^4a group, preferably in which: - R ⁵ and R ⁶ represent, independently of one another, a hydrogen atom or a linear or branched alkyl group, comprising from 1 to 24 carbon atoms, preferably from 1 to 12 carbon atoms, more preferably from 2 to 8 carbon atoms, and/or - X represents a sulfur atom, and/or - R ⁴ represents an SR ^4a group where R ^4a represents an R ^4b COOH group where R ^4b represents a linear or branched alkyl group, comprising from 1 to 24 carbon atoms, preferably from 1 to 12 carbon atoms, more preferably from 2 to 8 carbon atoms, more preferably in which: - R ⁵ and R ⁶ represent, independently of one another, a hydrogen atom or a linear or branched alkyl group, comprising from 1 to 24 carbon atoms, preferably from 1 to 12 carbon atoms, more preferably from 2 to 8 carbon atoms, and - X represents a sulfur atom, and - R ⁴ represents an SR ^4a group where R ^4a represents an R ^4b COOH group where R ^4b represents a linear or branched alkyl group, comprising from 1 to 24 carbon atoms, preferably from 1 to 12 carbon atoms, more preferably from 2 to 8 carbon atoms. 8. Additive package according to any one of claims 1 to 7, further comprising at least one phosphate compound, preferably corresponding to formula (7): [Chem 7]

in which: R ⁷ and R ⁸ are chosen independently of one another from a hydrogen atom or linear or branched, saturated or unsaturated hydrocarbon groups comprising from 4 to 24 carbon atoms, at least one of the two radicals R ⁷ or R ⁸ being a linear or branched, saturated or unsaturated hydrocarbon group comprising from 4 to 24 carbon atoms. 9. Additive package according to any one of claims 1 to 8, comprising: - at least 0.5% by weight, preferably from 0.5 to 20% by weight, more preferably from 1 to 10% by weight, or even from 2 to 5% by weight, of phosphite compound(s) of formula (1), - at least 1% by weight, preferably from 1 to 20% by weight, more preferably from 2 to 15% by weight, or even from 3 to 10% by weight, of thiadiazole compound(s), - optionally from 1 to 20% by weight, preferably from 2 to 15% by weight, preferably from 3 to 10% by weight, of compound(s) chosen from (i) a thiophosphate compound, preferably corresponding to formula (6), (ii) a phosphate compound, preferably corresponding to formula (7), and (iii) their mixture, - possibly up to 100% by weight of base oil(s) and/or additive(s) other than the phosphite, thiadiazole, phosphate and thiophosphate additives, relative to the total weight of the additive package. 10. Lubricating composition comprising: - at least 60% by weight of base oil(s), relative to the total weight of the lubricating composition, - at least one package of additives according to any one of claims 1 to 9. 11. Lubricating composition according to the preceding claim, comprising: - from 80 to 99.5% by weight, preferably from 85 to 99% by weight, of base oil(s), - from 0.5 to 20% by weight, preferably from 1 to 15% by weight, of the additive package, relative to the total weight of the lubricating composition. 12. Lubricating composition according to claim 10 or 11, comprising: - from 70 to 99% by weight, preferably from 85 to 99% by weight, of base oil(s), - from 0.01 to 5% by weight, preferably from 0.05 to 1% by weight, of phosphite compound(s), - from 0.01 to 5% by weight, preferably from 0.05 to 1% by weight, of thiadiazole compound(s), - optionally from 0.01 to 5% by weight, preferably from 0.05 to 1% by weight, of compound(s) chosen from (i) a thiophosphate compound, preferably corresponding to formula (6), (ii) a phosphate compound, preferably corresponding to formula (7), and (iii) their mixture, - optionally from 1 to 20% by weight of dispersant(s), preferably from 1 to 15% by weight, more preferably from 2 to 10% by weight, of dispersant(s), - optionally up to 100% by weight of additive(s) other than the phosphite, thiadiazole, thiophosphate, phosphate and dispersant additives, relative to the total weight of the lubricating composition. 13. Lubricating composition according to any one of claims 10 to 12, having a kinematic viscosity at 100°C ranging from 1 to 20 mm ² /s, preferably from 1.5 to 15 mm ² /s, more preferably from 2 to 10 mm ² /s. 14. Use of the additive package according to any one of claims 1 to 9, for preparing a lubricating composition intended to lubricate at least one mechanical part of a motor vehicle, said part preferably being a transmission member, and/or said motor vehicle preferably being an electric vehicle. 15. Use of the lubricating composition according to any one of claims 10 to 13, for lubricating at least one mechanical part of a motor vehicle, said part preferably being a transmission member, and/or said motor vehicle preferably being an electric vehicle.