WO2024110560A1

WO2024110560A1 - Lubricating composition for a motor vehicle drive train

Info

Publication number: WO2024110560A1
Application number: PCT/EP2023/082760
Authority: WO
Inventors: Goulven BOUVIER; Hakim EL-BAHI; Sonia YOUNESSE
Original assignee: Totalenergies Onetech
Priority date: 2022-11-23
Filing date: 2023-11-22
Publication date: 2024-05-30
Also published as: FR3142198A1

Abstract

The present invention relates to a lubricating composition comprising: - at least one base oil, - at least one additive corresponding to formula (I), in which R and R ¹ are chosen independently of one another from a hydrogen atom or the linear, saturated or unsaturated hydrocarbon groups, comprising from 8 to 20 carbon atoms, at least one of the two radicals R or R ¹ being a linear, saturated or unsaturated hydrocarbon group comprising from 8 to 20 carbon atoms.

Description

Title: Lubricating composition for automobile transmission.

Technical area

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

State of the art

Motor vehicle transmissions operate under heavy load and high speeds. Oils (also called “lubricating compositions” or “lubricants”) for these transmissions must therefore be particularly effective in protecting parts against wear and fatigue, and in particular protecting gear teeth against the phenomenon of seizure.

Seizing occurs under heavy load conditions and can be assessed by monitoring visual deterioration.

Preventing this phenomenon involves reducing contact stresses thanks to appropriate geometry of the parts, and reducing friction, by avoiding adhesion. The lubricating composition intervenes in this prevention process, mainly through the physicochemical reactivity of its additives.

Anti-wear and extreme pressure additives containing sulfur, phosphorus, or borate are generally added to give transmission oils protective properties against seizure. The other additives present in the lubricating composition can also have an impact, positive or negative, on this phenomenon.

Another advantage which the object of the invention must meet is to avoid the introduction of any additive, and more particularly of any extreme pressure anti-wear additive, comprising sulfur. It is desirable to limit, or even completely eliminate, sulfur from transmission oils, in particular for electric vehicle transmissions, in order to limit the occurrence of the corrosion phenomenon and to limit the conductivity values to the required levels.

Advantageously, the composition, object of the present invention, will not include any anti-wear additive based on Zinc. Document EP3546550A1 discloses a composition comprising the reaction product between an acid phosphate and a nitrogen compound.

Document EP3812445A1 discloses a composition comprising an acid phosphate comprising hydrocarbon groups of 1 to 6 carbon atoms.

The compounds described in these documents do not always have satisfactory lubricating properties, particularly in terms of durability and load capacity.

It is therefore an object of the present invention to provide a composition making it possible to lubricate the manual or automatic transmission members, in particular the transmission gears of thermal vehicles or preferably for electric vehicles, said composition having good durability and being devoid of any sulfur-based additive.

Summary of the invention

More specifically, the present invention relates to a lubricating composition comprising:

- at least one base oil,

- at least one additive corresponding to formula (I):

[Chem 1]

RC P—Oil

OR ' in which,

R and R ¹ are chosen independently of each other from a hydrogen atom or linear hydrocarbon groups, saturated or unsaturated, comprising from 8 to 20 carbon atoms, at least one of the two radicals R or R ¹ being a linear hydrocarbon group, saturated or unsaturated, comprising from 8 to 20 carbon atoms.

According to one embodiment, the hydrocarbon groups are chosen from alkyl groups and alkenyl groups.

According to one embodiment, R and R ¹ are chosen independently of each other from linear alkyl groups comprising from 8 to 18 carbon atoms. Preferably, the lubricating composition comprises:

- from 250 to 1300 ppm by weight of phosphorus, including preferably from 400 to 1400 ppm by weight of phosphorus provided by the additive(s) corresponding to formula (I) and/or

- less than 10 ppm by weight of sulfur, preferably less than 5 ppm by weight of sulfur, even preferably less than 1 ppm by weight of sulfur.

According to a preferred embodiment, the lubricating composition according to the invention further comprises at least one additive chosen from phosphites comprising from 1 to 24 carbon atoms, preferably from phosphites comprising from 4 to 12 carbon atoms, preferably among phosphites comprising two alkyl groups each having from 2 to 6 carbon atoms.

Preferably, the lubricating composition comprises from 0.01 to 10% by weight, preferably from 0.05 to 5% by weight, more preferably from 0.1 to 3% by weight, of additive(s) corresponding to formula (I) relative to the total weight of the lubricating composition.

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

- from 0.01 to 5% by weight, preferably from 0.02 to 2% by weight, of additive(s) corresponding to formula (I), and

- from 0.05 to 5% by weight, preferably from 0.1 to 2% by weight, of additive(s) chosen from phosphites comprising two alkyl groups each having from 2 to 6 carbon atoms.

According to one embodiment of the invention, the lubricating composition 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 of the invention, the lubricating composition comprises: - at least 70% by weight, preferably from 75 to 99.5% by weight of non-aqueous base oil(s);

- from 0.01% to 5% by weight, in particular from 0.02% to 2% by weight, of additive(s) corresponding to formula (I);

- from 0.05 to 5% by weight, preferably from 0.1% to 2% by weight, of additive(s) chosen from phosphites containing 1 to 24 carbon atoms;

- optionally from 0.1 to 15% by weight, preferably from 1 to 10% by weight, of one or more functional additives, preferably chosen from dispersants, antioxidants, pour point depressants, agents anti-foam and their mixtures, relative to the total weight of the lubricating composition.

Preferably, the base oil(s) have a kinematic viscosity at 100°C ranging from 1.5 to 35 cSt.

The invention also relates to the use of the lubricating composition according to the invention for lubricating at least one mechanical part of a motor vehicle, preferably present in a transmission member of a motor vehicle, preferably a gear of a motor vehicle.

The invention also relates to the use of an additive in a lubricating composition comprising at least one base oil, to improve the load capacity of the lubricating composition, said additive corresponding to formula (I):

[Chem 1]

in which,

- R and R ¹ are chosen independently of each other from a hydrogen atom or linear hydrocarbon groups, saturated or unsaturated, comprising from 8 to 20 carbon atoms, at least one of the two radicals R or R ¹ being a linear hydrocarbon group, saturated or unsaturated, comprising from 8 to 20 carbon atoms. Preferably, the additive corresponding to formula (I) is used in combination with an additive chosen from phosphites containing 1 to 24 carbon atoms, preferably with the following proportions in the lubricating composition:

- from 0.01 to 5% by weight, preferably from 0.02 to 2% by weight, of additive(s) corresponding to formula (I),

- from 0.05 to 5% by weight, preferably from 0.1 to 2% by weight, of additive(s) chosen from phosphites containing 1 to 24 carbon atoms, relative to the total weight of the lubricating composition.

Preferably, the lubricating composition used in the use of the additive according to the invention is as defined in the invention. In particular, the lubricating composition used in the use of the additive according to the invention has one or more of the following characteristics: the hydrocarbon groups are chosen from alkyl groups and alkenyl groups, and/or

- R and R ¹ are chosen independently of each other from linear alkyl groups comprising from 8 to 18 carbon atoms, and/or the lubricating composition comprises: o from 250 to 1300 ppm by weight of phosphorus, of which preferably from 400 to 1400 ppm by weight of phosphorus provided by the additive(s) corresponding to formula (I) and/or o less than 10 ppm by weight of sulfur, preferably less than 5 ppm by weight of sulfur, more preferably less than 1 ppm by weight of sulfur, and/or the lubricating composition further comprises at least one additive chosen from phosphites comprising from 1 to 24 carbon atoms, preferably from phosphites comprising from 4 to 12 carbon atoms, from preferably from phosphites comprising two alkyl groups each having from 2 to 6 carbon atoms, and/or the lubricating composition comprises from 0.01 to 10% by weight, preferably from 0.05 to 5% by weight, more preferably from 0.1 to 3% by weight, additive(s) corresponding to formula (I) relative to the total weight of the lubricating composition, and/or the lubricating composition comprises, relative to the total weight of the lubricating composition: o from 0.01 to 5% by weight, preferably from 0, 02 to 2% by weight, of additive(s) corresponding to formula (I), and o from 0.05 to 5% by weight, preferably from 0.1 to 2% by weight, of additive(s ) chosen from phosphites comprising two alkyl groups each having from 2 to 6 carbon atoms, and/or the lubricating composition further comprises at least one dispersant, preferably a borated dispersant, more preferably a borated dispersant chosen from borated succinimides, more preferably among borated polyisobutene succinimides, and/or the lubricating composition comprises, relative to the total weight of the lubricating composition: o at least 70% by weight, preferably from 75 to 99.5% by weight non-aqueous base oil(s); o from 0.01% to 5% by weight, in particular from 0.02% to 2% by weight, of additive(s) corresponding to formula (I); o from 0.05 to 5% by weight, preferably from 0.1% to 2% by weight, of additive(s) chosen from phosphites containing 1 to 24 carbon atoms; o optionally from 0.1 to 15% by weight, preferably from 1 to 10% by weight, of one or more functional additives, preferably chosen from dispersants, antioxidants, pour point depressants, agents defoamers and mixtures thereof, the base oil(s) have a kinematic viscosity at 100°C ranging from 1.5 to 35 cSt.

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

The lubricating composition has particularly satisfactory performance in reducing wear even under heavy load, even in the absence of sulfur-based additive and/or in the absence of zinc-based additive.

In the rest of the text, the expressions “between ... and . . . ", " 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 anti-wear additive corresponding to formula (I).

The lubricating composition according to the invention comprises at least one acid phosphate type additive corresponding to formula (I):

[Chem 1]

in which,

- R and R ¹ are chosen independently of each other from a hydrogen atom or linear hydrocarbon groups, saturated or unsaturated, comprising from 8 to 20 carbon atoms, at least one of the two radicals R or R ¹ being a linear hydrocarbon group, saturated or unsaturated, comprising from 8 to 20 carbon atoms.

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

Preferably, the hydrocarbon groups are chosen from alkyl groups and alkenyl groups.

According to one embodiment, R and R ¹ are chosen independently of each other from a hydrogen atom or linear alkyl groups comprising from 8 to 20 carbon atoms, preferably, R and R ¹ are chosen independently one from the other among linear alkyl groups comprising from 8 to 18 carbon atoms, it being understood that at least one of the groups R or R ¹ is a linear alkyl group.

The lubricating composition may optionally comprise a mixture of compounds corresponding to formula (I).

Preferably, the anti-wear(s) corresponding to formula (I) provide(s) from 250 to 1300 ppm by weight of phosphorus.

Preferably, the anti-wear additive(s) of formula (I) represents(s) from 0.01 to 10% by weight, preferably from 0.05 to 5% by weight, more preferably from 0. 1 to 3% by weight of the total weight of the lubricating composition according to the invention.

Phosphite type anti-wear additive

According to an advantageous embodiment of the invention, the lubricating composition according to the invention comprises an anti-wear additive chosen from phosphites comprising from 1 to 24 carbon atoms, preferably from phosphites comprising from 4 to 12 carbon atoms .

Advantageously, the phosphite type anti-wear additive is chosen from phosphites comprising two alkyl groups each having from 2 to 6 carbon atoms.

Particularly advantageously, the phosphite type anti-wear additive is dibutyl hydrogen phosphite. According to one embodiment, the phosphite type anti-wear additive represents 0.05 to 5% by weight, preferably 0.1 to 2% by weight, of the total weight of the lubricating composition according to the invention.

According to one embodiment of the invention, the lubricating composition comprises:

- from 0.01 to 5% by weight, preferably from 0.02 to 2% by weight, of anti-wear additive(s) corresponding to formula (I) where R and R ¹ are chosen independently from one of the other from a hydrogen atom or linear, saturated or unsaturated hydrocarbon groups, comprising from 8 to 20 carbon atoms, at least one of the two radicals R or R ¹ being a linear, saturated or unsaturated hydrocarbon group, comprising from 8 to 20 carbon atoms, and

- from 0.05 to 5% by weight, preferably from 0.1 to 2% by weight, of anti-wear additive(s) chosen from phosphites containing 1 to 24 carbon atoms, relative to the weight total of the lubricating composition.

- from 0.01 to 5% by weight, preferably from 0.02 to 2% by weight, of anti-wear additive(s) corresponding to formula (I) where R and R ¹ are chosen independently from one of the other among linear, saturated or unsaturated alkyl or alkenyl groups, comprising from 8 to 20 carbon atoms, and

- from 0.01 to 5% by weight, preferably from 0.02 to 2% by weight, of anti-wear additive(s) corresponding to formula (I) where R and R ¹ are chosen independently from one of the another among linear alkyl groups comprising from 8 to 18 carbon atoms, and - from 0.05 to 5% by weight, preferably from 0.1 to 2% by weight, of anti-wear additive(s) chosen from phosphites comprising two alkyl groups each having from 2 to 6 carbon atoms , relative to the total weight of the lubricating composition.

Base oil(s)

The lubricating composition according to the invention comprises one or more base oils, preferably in a content of at least 70% by weight, preferably ranging from 75 to 99.5% by weight, more preferably from 80 to 99%. by weight, preferably from 85 to 98% by weight, relative to the total weight of the lubricating composition.

Preferably, the lubricating composition 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 oils of the lubricating composition according to the invention have a kinematic viscosity at 100°C ranging from 1.5 to 35 cSt.

These base oils can be chosen 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 of the lubricating compositions considered according to the invention 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, desalphating, solvent dewaxing, hydrotreating, hydrocracking, hydroisomerization and hydrofinishing .

Blends of synthetic and mineral oils, which can be biosourced, 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, particularly in terms of viscosity, viscosity index, or resistance to oxidation, suitable for use for 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 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 the 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 base oils of the lubricating composition according to the invention can be chosen from group II or III base oils. According to an alternative embodiment, the base oil or oils of the composition used according to the invention are chosen from polyalphaolefins (PAO), polyalkylene glycol (PAG) and esters of carboxylic acids and alcohols.

Complementary additives

The lubricating composition according to the invention may also comprise all types of functional additives, distinct from the anti-wear of formula (I) and distinct from the anti-wear of the phosphite type defined in the present invention, suitable for use in a lubricant for motor vehicles, in particular for manual or automatic transmission of motor vehicles.

Such additives, known to those skilled in the art in the field of motor vehicle lubrication, can be chosen from detergents, dispersants, antioxidants, pour point depressants, anti-foaming agents, water improvers. viscosity index, and their mixtures.

Advantageously, the composition according to the invention comprises at least one functional additive chosen from detergents, dispersants, antioxidants, pour point depressants, anti-foaming agents, viscosity index improvers, and mixtures thereof. .

Typically, when present, these additional functional additives represent (in total) from 1 to 30% by weight, preferably from 1.5 to 25% by weight, preferably from 2 to 20% by weight, of the weight total of the lubricating composition.

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

The lubricating composition according to the invention may comprise at least one antioxidant additive.

The antioxidant additive generally makes it possible to delay the degradation of the composition in service. This degradation can 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 free radical inhibitors or hydroperoxide destroyers. Among the commonly used antioxidant additives, mention may be made of phenolic-type antioxidant additives and amine-type antioxidant additives. Phenolic antioxidant additives can 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 alkyl group in Cl -Cl 2, 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 alkyl group in Ci-Cio, preferably an alkyl group in CI-CÔ, preferably a C4 alkyl group, preferably by the tert-butyl group.

Amino compounds are another class of antioxidant additives that can be used, possibly in combination with phenolic antioxidant additives. Examples of amino compounds are aromatic amines, for example aromatic amines of 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 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, a alkenyl group or an aryl group and z represents 0, 1 or 2.

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

Another class of antioxidant additives is that of copper compounds, for example copper salts and carboxylic acids, copper phenates, copper acetylacetonates. Copper I and II salts, succinic acid or anhydride salts can also be used.

The lubricating composition according to the invention may contain all types of antioxidant additives known to those skilled in the art. Advantageously, the lubricating composition according to the invention comprises at least one ash-free antioxidant additive.

The lubricating composition according to the invention may comprise from 0.5 to 2% by weight of at least one antioxidant additive, relative to the total weight of the composition.

The lubricating composition according to the invention may also comprise at least one detergent additive.

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

The detergent additives which can be used in the lubricating composition according to the invention are generally known to those skilled in the art. The detergent additives may be anionic compounds comprising a long lipophilic hydrocarbon chain and a hydrophilic head. The associated cation may 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, salicylates, naphthenates, as well as phenate salts. The alkali and alkaline earth metals are preferably calcium, magnesium, sodium or barium.

These metal salts generally include the metal in stoichiometric quantity or in excess, therefore in quantity greater than the stoichiometric quantity. 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 the oil, for example a carbonate, a hydroxide, an oxalate, an acetate, a glutamate, preferably a carbonate .

The lubricating composition suitable for the invention may for example comprise from 0.5 to 4% by weight of detergent additive, relative to the total weight of the composition.

Also, the lubricating composition according to the invention may comprise at least one dispersing agent. Typically, the dispersant will ensure the maintenance in suspension and evacuation of insoluble solid contaminants consisting of secondary oxidation products which form when the lubricating composition is in use.

The dispersing agent can be chosen from Mannich bases, succinimide type compounds, such as polyisobutylene succinimide (PIBSI), optionally borated, or borated dispersants other than succinimides, preferably from borated dispersants, more preferably from borated succinimide dispersants, particularly borated SI PIBs.

The lubricating composition according to the invention may for example comprise from 0.2 to 10% by weight of dispersing agent(s), relative to the total weight of the composition.

The lubricating composition according to the invention may further comprise at least one anti-foaming agent.

The anti-foaming agent can be chosen from silicones.

The lubricating composition according to 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 agent antifoam, relative to the total weight of the composition.

The lubricating composition according to the invention may also comprise at least one pour point depressant additive (also known as “PPD” agents for “Pour Point Depressant” in English).

By slowing the formation of paraffin crystals, pour point depressant additives generally improve the cold behavior of the composition. As an example of pour point depressant additives, mention may be made of polyalkyl methacrylates, polyacrylates, polyarylamides, polyalkylphenols, polyalkylnaphthalenes, alkylated polystyrenes.

The lubricating composition according to the invention may also comprise at least one additive improving the viscosity index (VI improver). As an example of VI improver, mention may be made of polymethacrylates, polyisobutenes or fatty acid esters. When present, these additives can represent from 1 to 25% by weight of the total weight of the lubricating composition. Preferably, the lubricating composition according to the invention does not comprise anti-wear additives comprising zinc.

In terms of formulation of such a lubricating composition, the anti-wear additive(s) according to the invention can be added to a base oil or mixture of oils, then other possible additional additives added.

Alternatively, the anti-wear additive(s) according to the invention can be added to a pre-existing conventional lubricating formulation, comprising in particular one or more base oils, and possibly additional additives.

Alternatively, the anti-wear additive(s) according to the invention can be combined with one or more additional additives when they are present, and the “package” of additives thus formed added to a base oil or mixture of oils.

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, in particular from 10 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, in particular from 2 to 15 mm ² /s.

Preferably, the lubricating composition comprises from 400 to 1400 ppm by weight of phosphorus, including advantageously from 250 to 1300 ppm by weight of phosphorus provided by the anti-wear(s) corresponding to formula (I).

Preferably, the lubricating composition is substantially free of sulfur, preferably completely free of sulfur.

In particular, the lubricating composition according to the invention preferably does not comprise additives comprising sulfur.

Thus, the lubricating composition according to the invention typically comprises less than 10 ppm by weight of sulfur, or even less than 5 ppm by weight of sulfur, or even less than 1 ppm by weight of sulfur. According to a particular embodiment, the lubricating composition according to the invention comprises, or even consists of:

- a base oil or mixture of base oils;

- an anti-wear additive corresponding to formula (I);

- optionally an anti-wear additive chosen from phosphites containing 1 to 24 carbon atoms;

- optionally one or more additional additives chosen from dispersants, antioxidants, pour point depressants, anti-foaming agents and their mixtures.

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

- at least 70% by weight, preferably from 75 to 99.5% by weight of base oil(s);

- from 0.01% to 10% by weight, in particular from 0.05% to 5% by weight, of anti-wear additive(s) corresponding to formula (I);

- optionally from 0.05 to 5% by weight, in particular from 0.1% to 2% by weight, of anti-wear additive(s) chosen from phosphites containing 1 to 24 carbon atoms;

- at least 70% by weight, preferably from 75 to 99.5% by weight of base oil(s);

- from 0.01% to 5% by weight, in particular from 0.02% to 2% by weight, of anti-wear additive(s) corresponding to formula (I);

- from 0.05 to 5% by weight, preferably from 0.1% to 2% by weight, of anti-wear additive(s) chosen from phosphites containing 1 to 24 carbon atoms;

- optionally from 0.1 to 15% by weight, preferably from 1 to 10% by weight, of one or more functional additives, preferably chosen from dispersants, antioxidants, pour point depressants, agents anti-foam and their mixtures, relative to the total weight of the lubricating composition. According to a particular embodiment, the lubricating composition according to the invention comprises:

- at least 70% by weight, preferably from 75 to 99.5% by weight, of base oil(s);

- from 0.05 to 5% by weight, preferably from 0.1% to 2% by weight, of additive(s) chosen from phosphites containing 1 to 24 carbon atoms, preferably 4 with 12 carbon atoms, preferably among phosphites comprising two alkyl groups each having from 2 to 6 carbon atoms;

- at least 70% by weight, preferably from 75 to 99.5% by weight of base oil(s);

- optionally from 0.1 to 15% by weight, preferably from 1 to 10% by weight, of one or more functional additives, preferably chosen from dispersants, antioxidants, pour point depressants, agents anti-foam and mixtures thereof, said composition comprising less than 10 ppm by weight of sulfur, relative to the total weight of the lubricating composition.

- at least 70% by weight, preferably from 75 to 99.5% by weight of base oil(s);

- from 0.01 to 5% by weight, preferably from 0.02 to 2% by weight, of anti-wear additive(s) corresponding to formula (I) where R and R ¹ are chosen independently of each other from linear alkyl groups comprising from 8 to 18 carbon atoms;

- from 0.05 to 5% by weight, preferably from 0.1 to 2% by weight, of anti-wear additive(s) chosen from phosphites comprising two alkyl groups each having from 2 to 6 atoms of carbon ;

- at least 70% by weight, preferably from 75 to 99.5% by weight of base oil(s);

- from 0.5 to 5% by weight, preferably from 0.1% to 2% by weight, of dispersant(s), preferably chosen from borated dispersants;

- optionally from 0.1 to 10% by weight, preferably from 0.5 to 5% by weight, of one or more functional additives, preferably chosen from antioxidants, pour point depressants, anti -foam and their mixtures, relative to the total weight of the lubricating composition.

The present invention also relates to the use of the lubricating composition according to the invention to lubricate the transmissions of motor vehicles, in particular the gears of the transmissions. Transmissions can 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 transmission gears.

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

The invention also relates, according to another of its aspects, to a method of 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 bringing at least said part into contact with a lubricating composition as described above.

The invention also relates, according to another of its aspects, to a process for improving the durability of a lubricating composition, said process comprising a step of mixing at least one anti-wear additive of formula (I) such as defined in the present invention, with at least one base oil, preferably said anti-wear additive of formula (I) is further mixed with an anti-wear additive chosen from phosphites comprising from 1 to 24 carbon atoms.

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 by way of illustration and not limitation of the invention. Examples

Example 1: Preparation of lubricating compositions

The lubricating compositions were prepared by mixing the ingredients at a temperature of approximately 40°C, according to methods well known to those skilled in the art. The lubricating compositions which were prepared and tested are detailed in Tables 2 and 3 below.

The elemental phosphorus and sulfur contents were calculated based on the elemental contents in the ingredients and are also shown in Table 2 in ppm by weight.

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

[Table 2]

In the compositions of table 2:

- the base oils are group III base oils, - the anti-wear II corresponds to formula (I) where R and RI are two linear C8 alkyl chains, - the anti-wear PI is dibutyl hydrogen phosphite,

- anti-wear Cl does not meet formula (I) since it is an acid phosphate with branched chains comprising 8 carbon atoms,

- anti-wear C2 does not meet formula (I) since it is an acid phosphate with chains containing 5 carbon atoms,

- the dispersant is a borated PIB SI dispersant making it possible to provide approximately 85 ppm of boron,

- the antioxidant comprises a phenolic antioxidant and/or an amino antioxidant,

- the anti-corrosion is a triazole derivative,

- the additive package contains a pour point improver and an anti-foam.

Example 2: Studies of the performance of lubricating compositions

The seizure load capacity of the lubricating compositions described in Table 2 was tested by the FZG A10/16.6R/90 method (according to the modified CEC-L-84-02 standard). The results are shown in Table 4 below.

The average coefficient of friction was determined on an MTM machine (mini traction machine) with the following conditions:

- load = 5N,

- rolling speed/drive speed = 3 mm/s,

- temperature = 90°C,

- duration = 10 minutes,

- SSR (slide-roll ratio or in French “rollover rate”) = 330%.

[Table 4]

The compositions according to the invention Cil to CI4 have very good loading capacity. These load capacity values (FZG) demonstrate the very good durability of the lubricating composition, particularly for use in transmissions. The compositions according to the invention Cil to CI4 also have a lower average coefficient of friction, demonstrating better lubricating properties.

The anti-wear products corresponding to formula (I) as defined in the present invention make it possible to improve the performance of the lubricating composition. More particularly, the anti-wear corresponding to formula (I) as defined in the present invention have better properties than the anti-wear C1 and C2 of the state of the art.

Claims

1. Lubricating composition comprising:

- at least one base oil,

- at least one additive corresponding to formula (I):

[Chem 1]

O

RO — P ■— 011

ÔR' in which,

R and R ¹ are chosen independently of each other from a hydrogen atom or linear hydrocarbon groups, saturated or unsaturated, comprising from 8 to 20 carbon atoms and optionally comprising one or more heteroatoms, at least one of the two radicals R or R ¹ being a linear hydrocarbon group, saturated or unsaturated, comprising from 8 to 20 carbon atoms.

2. Lubricating composition according to claim 1, in which the hydrocarbon groups are chosen from alkyl groups and alkenyl groups.

3. Lubricating composition according to any one of the preceding claims, in which R and R ¹ are chosen independently of each other from linear alkyl groups comprising from 8 to 18 carbon atoms.

4. Lubricating composition according to any one of the preceding claims, comprising:

5. Lubricating composition according to any one of the preceding claims, further comprising at least one additive chosen from phosphites comprising from 1 to 24 carbon atoms, preferably from phosphites comprising 4 to 12 carbon atoms, preferably among phosphites comprising two alkyl groups each having 2 to 6 carbon atoms.

6. Lubricating composition according to the preceding claim, comprising from 0.01 to 10% by weight, preferably from 0.05 to 5% by weight, more preferably from 0.1 to 3% by weight, of additive(s). ) corresponding to formula (I) relative to the total weight of the lubricating composition.

7. Lubricating composition according to one of the preceding claims, comprising, relative to the total weight of the lubricating composition:

8. Lubricating composition according to any one of the preceding claims, 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.

9. Lubricating composition according to any one of the preceding claims, comprising: at least 70% by weight, preferably from 75 to 99.5% by weight, of base oil(s); from 0.01% to 5% by weight, in particular from 0.02% to 2% by weight, of additive(s) corresponding to formula (I); from 0.05 to 5% by weight, preferably from 0.1% to 2% by weight, of additive(s) chosen from phosphites comprising from 1 to 24 carbon atoms, preferably from 4 to 12 carbon atoms, preferably from phosphites comprising two alkyl groups each having from 2 to 6 carbon atoms; relative to the total weight of the lubricating composition.

10. Lubricating composition according to any one of the preceding claims, comprising: at least 70% by weight, preferably from 75 to 99.5% by weight of non-aqueous base oil(s); from 0.01% to 5% by weight, in particular from 0.02% to 2% by weight, of additive(s) corresponding to formula (I); from 0.05 to 5% by weight, preferably from 0.1% to 2% by weight, of additive(s) chosen from phosphites containing 1 to 24 carbon atoms; optionally from 0.1 to 15% by weight, preferably from 1 to 10% by weight, of one or more functional additives, preferably chosen from dispersants, antioxidants, pour point depressants, anti -foam and their mixtures, relative to the total weight of the lubricating composition.

11. Lubricating composition according to any one of the preceding claims, in which the base oil(s) have a kinematic viscosity at 100°C ranging from 1.5 to 35 cSt.

12. Use of the composition according to any one of claims 1 to 11, for lubricating at least one mechanical part of a motor vehicle, preferably present in a transmission member of a motor vehicle, preferably a gear. a motor vehicle.

13. Use of an additive in a lubricating composition comprising at least one base oil, to improve the load capacity of the lubricating composition, said additive corresponding to formula (I):

[Chem 1]

in which,

- R and R ¹ are chosen independently of each other from a hydrogen atom or linear hydrocarbon groups, saturated or unsaturated, comprising from 8 to 20 carbon atoms and optionally comprising one or more heteroatoms, at least l one of the two radicals R or R ¹ being a linear hydrocarbon group, saturated or unsaturated, comprising from 8 to 20 carbon atoms.

14. Use according to claim 13, in which the additive corresponding to formula (I) is used in combination with an additive chosen from phosphites comprising from 1 to 24 carbon atoms, preferably with the following proportions in the lubricating composition :

15. Use according to claim 13 or 14, in which the lubricating composition is as defined in any one of claims 2 to 11.