EP3430110A1

EP3430110A1 - Polyalkylene glycol-based lubricant composition

Info

Publication number: EP3430110A1
Application number: EP17710731.5A
Authority: EP
Inventors: Laura BROUTIN; Nicolas Obrecht; Nadjet KHELIDJ-SUEDMEYER
Original assignee: Total Marketing Services SA; Dow Global Technologies LLC
Current assignee: TotalEnergies Onetech SAS; Dow Global Technologies LLC
Priority date: 2016-03-15
Filing date: 2017-03-14
Publication date: 2019-01-23
Also published as: US20190078036A1; KR20180126477A; WO2017157892A1; FR3048977B1; BR112018068689A2; FR3048977A1; JP2019508561A; KR102336568B1; MX2018011050A; CN109072120A

Abstract

The present application relates to a lubricant composition comprising: - an oil selected from among polyalkylene glycols (PAG); and - a wear-resistant additive selected from among the compounds of formula (I) where R1 and R2 are identical or different and independently represent a linear or branched secondary alkyl group containing 2 to 7 carbon atoms, preferably 3 to 6 carbon atoms. Said lubricant composition is particularly useful for lubricating a vehicle engine, preferably a motor vehicle engine.

Description

LUBRICATING COMPOSITION BASED ON POLYALKYLENE GLYCOLS

The present application relates to the field of lubricating compositions, especially lubricating compositions for a vehicle engine, in particular for a motor vehicle engine. In particular, the present application relates to lubricating compositions based on polyalkylated glycols (PAG or polyalkylene glycols) for the

vehicle engine lubrication, especially motor vehicle.

Energy efficiency and reduced fuel consumption of automotive engines is a growing concern. It is known that engine lubricants used in said vehicles have an important role in this regard.

To formulate "fuel-eco" lubricants or fuel economizers, it is known to play on the viscosity of the lubricating bases used. It is also known to use viscosity index (VI) improving polymers, or to use friction modifiers (MF). However, the viscosity index improvers have the disadvantage of degrading the engine cleanliness of the lubricating compositions in which they are employed. However, current engines have high thermal stresses that cause significant deposition phenomena. The deposits are related to the chemical transformation of the lubricant in the parts closest to the combustion chamber and therefore the hottest ones.

"Fuel-Eco" lubricant compositions based on PAG have been described in document WO 2013/164449, said compositions also having good motor properties.

However, the use of these PAGs can sometimes cause an increase in the wear of the mechanical parts of the engine, and therefore a degradation of the durability of said engine.

There is therefore an interest in providing a lubricant composition, especially a lubricating composition for motor vehicle engines, to meet all or part of the disadvantages of the prior art. An object of the present invention is to provide a lubricant composition based on PAG, in particular a lubricant composition based on PAG for motor vehicle engines, having improved anti-wear properties.

Another object of the present invention is to provide a lubricant composition based on PAG, in particular a lubricant composition based on PAG for a vehicle engine. automotive, having both improved anti-wear properties and satisfactory "Fuel-Eco" properties.

Another object of the present invention is to provide a lubricating composition based on PAG, especially a PAG lubricant composition for a motor vehicle engine, having both improved anti-wear properties and does not degrade engine cleanliness.

Another object of the present invention is to provide a lubricant composition based on PAG, especially a PAG lubricant composition for a motor vehicle engine, having improved anti-wear properties, satisfactory "Fuel-Eco" properties and not not degrading engine cleanliness.

Another object of the invention is to provide a lubricant composition based on PAG, in particular a lubricant composition based on PAG for motor vehicle engine, having improved anti-wear properties and easy to formulate. In order to meet the above objectives and the drawbacks cited in the state of the art, the present invention proposes a lubricant composition comprising:

an oil chosen from polyalkylated glycols (PAGs or polyalkylene glycols), and

an anti-wear additive chosen from compounds of formula (I)

(I)

in which R1 and R2, which may be identical or different, independently represent a linear or branched secondary alkyl group comprising from 2 to 7 carbon atoms, preferably from 3 to 6 carbon atoms. In the context of the present invention, the term "linear or branched secondary alkyl comprising from 2 to 7 carbon atoms" means an alkyl chosen so as to form with the O to which it is attached a secondary alcohol.

Particularly advantageously, the lubricant composition of the present invention is a lubricant composition for an engine, preferably a vehicle, more preferably a motor vehicle. According to the invention, the PAG of the lubricant composition according to the invention may be a block polymer or a random polymer.

The PAG according to the invention comprises alkyl groups whose length of the hydrocarbon chains may vary. According to the invention, the length of the hydrocarbon chains is defined by a mean value of the number of carbon atoms. Preferably, the PAG of the composition according to the invention PAG is a block polymer of formula (II) or a random polymer of formula (II)

in which

^■ R 3 is a C ₃₀ linear alkyl group or branched, preferably a C ₂ -C ₄ linear or branched alkyl;

^■ n is a number from 2 to 60, preferably from 5 to 30 or 7 to 15;

^■ R4 and R5, identical or different, independently represent a hydrogen atom or a dC ₂ alkyl group.

For the PAG according to the invention, n can represent a number ranging from 2 to 60, preferably ranging from 5 to 30 or from 7 to 15.

For a preferred PAG according to the invention, R 3 represents a linear or branched C ₄ -C ₁₂ -alkyl group, R 4 and R 5 are different and independently represent a hydrogen atom or a linear C ₁ -C ₂ -alkyl group and n represents a number ranging from 7 to 15.

Also preferably, the PAG of the composition according to the invention is a block polymer of formula (MA) or a random polymer of formula (MA)

(IIA)

in which

^■ R 3 is a C ₃₀ linear alkyl group or branched, preferably a C ₂ -C ₄ linear or branched alkyl; ^■ m is a number from 2 to 60, preferably from 5 to 30 or 7 to 15;

^■ R6 and R7 represent a hydrogen atom; or R6 represents a hydrogen atom and R7 represents a methyl group; or R6 represents a methyl group and R7 represents a hydrogen atom; or R6 and R7 represent a methyl group; or R6 represents an ethyl group and R7 represents a hydrogen atom; or R6 represents a hydrogen atom and R7 represents an ethyl group. For the PAG according to the invention, m may represent a number ranging from 2 to 60, preferably ranging from 5 to 30 or from 7 to 15.

In a preferred PAG of the invention, R3 represents a group C ₂ -C ₄ linear or branched alkyl, R6 and R7 are different and independently represent a hydrogen atom, a methyl group or an ethyl group and m represents a number ranging from 7 to 15.

Also preferably, the PAG of the composition according to the invention is a block polymer of formula (MB) or a random polymer of formula (MB)

(MB)

in which

^■ R 3 is a C ₃₀ linear alkyl group or branched, preferably a C ₂ -C ₄ linear or branched alkyl, more preferably a C ₈ -C ₁₂ linear or branched alkyl; P and q independently represent a number ranging from 1 to 30, preferably from 2 to 15 or from 2 to 8;

^■ R8 and R9 represent a hydrogen atom; or R8 represents a hydrogen atom and R9 represents a methyl group; or R8 represents a methyl group and R9 represents a hydrogen atom; or R8 and R9 represent a methyl group; or R8 represents an ethyl group and R9 represents a hydrogen atom; or R8 represents a hydrogen atom and R9 represents an ethyl group; ^■ R1 R1 0 and 1 represent a hydrogen atom; or R 1 0 represents a hydrogen atom and R 1 1 represents a methyl group; or R10 represents a methyl group and R1 1 represents a hydrogen atom; or R 1 0 and R 1 1 represent a methyl group; or R 10 represents an ethyl group and R 1 represents a hydrogen atom; or R 1 0 represents a hydrogen atom and R 1 1 represents an ethyl group.

For the PAG according to the invention, p and q may independently represent a number ranging from 1 to 30, preferably from 2 to 15 or from 2 to 8.

As particular PAG according to the invention, mention may be made

^■ PAG for which R8, R9, R10 and R1 1 represents a hydrogen atom; or

^■ PAG for which R8 and R1 0 represents a hydrogen atom and R9 and R1 1 are methyl; or

the PAGs for which R8 and R10 represent a hydrogen atom and R9 and R1 1 represent an ethyl group; or

^■ PAG for which R8 and R10 represent a hydrogen atom, R9 represents a methyl group and R1 1 is ethyl; or

^■ PAG for which R8 and R10 represent a hydrogen atom, R9 is ethyl and R1 1 represents a methyl group; or

^■ PAG for which R8, R9 and R1 1 represents a hydrogen atom and R10 represents a methyl group; or

^■ PAG for which R8, R1 0 and R1 1 represents a hydrogen atom and R9 represents a methyl group.

For a preferred PAG according to the invention, R 3 represents a linear or branched C ₄ -C ₁₂ -alkyl group, R 8, R 1 0 and R 1 1 represent a hydrogen atom and R 9 represents a methyl group, p represents a number ranging from 3 to 5, for example 4.5, and q represents a number from 1 to 3, for example 2.

In a more preferred PAG of the invention, R3 represents a group C ₂ -C ₈ linear or branched alkyl, R8 represents a hydrogen atom and R9 represents a methyl group, R10 represents a hydrogen atom and R1 1 represents an ethyl group, p represents a number ranging from 3 to 8, for example 5, and q represents a number ranging from 3 to 8, for example 4. More preferably, the PAG of the composition according to the invention is a block polymer of formula (III) or a random polymer of formula (III)

(III)

in which

^■ R3 represents a group C ₄ -C ₁₂ linear or branched alkyl, preferably a C ₄ linear or branched alkyl;

^■ p represents a number from 1 to 30, preferably from 2 to 15 or 2 to 8;

^■ q is a number from 1 to 30, preferably from 1 to 10.

Examples of PAG of formula (III) include the products of the Synalox 50-B® range marketed by Dow Chemical.

More particularly preferably, the PAG of the composition according to the invention is a block polymer of formula (IV) or a random polymer of formula (IV)

(IV)

in which

^■ R3 represents a group C ₂ -C ₈ linear or branched alkyl;

^■ p represents a number from 2 to 6;

^■ q represents a number ranging from 2 to 5.

The PAG used for the composition according to the invention may be prepared by reacting at least one alcohol-type initiator comprising from 1 to 30 carbon atoms with the epoxy bonding of one or more alkylene oxides and then propagation of the reaction. to obtain these polymers. The preferred alkylene oxides are ethylene oxide, propylene oxide and butylene oxide. Processes for preparing PAG of formula (IV) are described in international patent application WO-2012/070007 or in international patent application WO-2013/164449.

More particularly preferably, the PAG of the composition according to the invention is a block polymer of formula (V) or a random polymer of formula (V)

(V)

in which

^■ R3 represents a group C ₂ -C ₄ linear or branched alkyl, preferably a C ₄ linear or branched alkyl;

^■ r is a number from 2 to 60, preferably from 5 to 30 or 7 to 15.

As examples of PAG of formula (III), mention may be made of the products of the Synalox 100-B® range marketed by Dow Chemical.

More preferably, the PAG is a block polymer of formula (VI) or a random polymer of formula (VI)

(VI)

in which

^■ R 12 is a group CC ₃₀ linear or branched alkyl, preferably a C ₈ -C ₁₅ linear or branched alkyl;

^■ s and t independently represent an average number ranging from 1 to 5.

For a preferred PAG according to the invention, R12 represents a group chosen from a linear C ₈ -alkyl group; a branched C ₈ -alkyl group; a linear C ₉ -alkyl group; a branched C ₉ -alkyl group; a linear C ₁₀ -alkyl group; C ₁₀ -alkyl branched; a linear C n -alkyl group; a branched C n -alkyl group; a linear C ₁₂ -alkyl group; a branched C ₁₂ -alkyl group; a linear C ₁₃ -alkyl group; a branched C ₁₃ -alkyl group; a linear C ₁₄ -alkyl group; a branched C ₁₄ -alkyl group; a linear C ₁₅ -alkyl group; a branched C ₁₅ -alkyl group.

For a preferred PAG according to the invention:

^■ s is greater than or equal to t; or

^■ s represents an average number ranging from 2 to 4.5; or

^■ t is an average number ranging from 1, 5 to 4.

For a preferred PAG according to the invention:

^■ s represents an average number ranging from 2.5 to 3.5; or

^■ t represents an average number of from 2 to 3.

For a preferred PAG according to the invention:

^■ s represents an average number equal to 2.5 and t represents an average number equal to 2; or

^■ s represents an average number equal to 3.5 and t represents an average number equal to 2.8.

For a preferred PAG according to the invention:

^■ a kinematic viscosity at 100 ° C as measured according to ASTM D445, is from 2.5 to 4.5 mm ² .s ^"1, or which

^■ its viscosity index is greater than 160 or is between 160 and 210; or whose

^■ its pour point is less than -40 ° C; or whose

^■ its dynamic viscosity (CCS) at -35 ° C as measured according to ASTM D5293 of less than 1200 mPa.s.

Methods for preparing PAG of formula (VI) are described in application WO-2016/016362.

Preferably, the PAG according to the invention comprises at least one butylene oxide unit.

Preferably, the lubricant composition according to the invention comprises from 1 to 99.5% by weight of PAG. Preferably, the lubricating composition according to the invention comprises from 1 to 99.5%, preferably from 5 to 80%, for example from 5 to 70%, from 5 to 60%, from 5 to 50%, from 5 to 40%, preferably from 10 to 80%, for example from 10 to 70%, from 10 to 60%, from 10 to 50%, from 10 to 40%, preferably from 20 to 80%, for example from 20 to 70%, 20 to 60%, 20 to 50%, 20 to 40%, preferably 30 to 80%, for example 30 to 70%, 30 to 60%, 30 to 50%, 30 to 40% by weight of PAG.

More preferably, the lubricating composition according to the invention comprises from 1 to 30%, preferably from 1 to 20%, more preferably from 1 to 15% by weight of PAG.

In a more preferred manner, the lubricating composition according to the invention comprises from 40 to 99.5%, preferably from 50 to 99.5%, more preferably from 60 to 99.5%, even more preferably from 70 to 99%, 5%, advantageously 80 to 99.5% by weight of PAG.

In addition to a PAG, the lubricant composition according to the invention comprises an anti-wear additive chosen from compounds of formula (I)

(I)

in which R1 and R2, which may be identical or different, independently represent a linear or branched secondary alkyl group comprising from 2 to 7 carbon atoms, preferably from 3 to 6 carbon atoms.

In a preferred manner, the antiwear additive is chosen from compounds of formula (I)

R1- O S S O RI

V V Y

R2- O ^' SS ^' Ό- R2

(I)

in which R1 and R2, identical or different, represent a secondary C3-alkyl group or a secondary C6-alkyl group. More preferably, the groups R 1 and R 2, which are identical or different, represent a dimethyl butyl group or an isopropyl group. Even more preferably, the groups R 1 and R 2, which are identical, represent a dimethyl butyl group or an isopropyl group.

In yet another more preferred way, the anti-wear additive comprises a mixture:

at least one compound of formula (I) in which R1 represents a secondary C3-alkyl group and R2 represents a secondary C6-alkyl group,

at least one compound of formula (I) in which R1 and R2, which are identical, represent a secondary C6-alkyl group.

In yet another more preferred embodiment, the anti-wear additive comprises a mixture of: at least one compound of formula (I) in which R 1 represents a secondary C 6 -alkyl group and R 2 represents a secondary C 3 -alkyl group ,

at least one compound of formula (I) in which R1 and R2, which are identical, represent a secondary C6-alkyl group. As examples of compounds of formula (I), mention may be made of Lubrizol 1371® product marketed by Lubrizol.

Preferably, the lubricating composition according to the invention comprises from 0.1 to 3%, preferably from 0.1 to 2%, more preferably from 0.1 to 1% by weight of compound of formula (I).

In addition to a PAG and a compound of formula (I), the lubricating composition according to the invention may comprise a base oil.

In general, the lubricating composition according to the invention may comprise any type of lubricating base oil, mineral, synthetic or natural, animal or plant adapted to its use.

The base oils used in the lubricant compositions according to the invention can therefore be oils of mineral or synthetic origins belonging to groups I to V according to the classes defined in the API classification (or their equivalents according to the ATIEL classification) (Table A ) or their mixtures. Preferably, the base oil is different from the PAG.

Table A The mineral base oils that can be used for the lubricating composition according to the invention include any type of bases obtained by atmospheric and vacuum distillation of crude oil, followed by refining operations such as solvent extraction, desalting, solvent dewaxing, hydrotreating, hydrocracking, hydroisomerization and hydrofinishing. Mixtures of synthetic and mineral oils can also be used.

There is generally no limitation on the use of different lubricating bases to make the lubricating compositions according to the invention, except that they must have properties, in particular viscosity, viscosity index, sulfur content. and oxidation resistance, especially adapted for use for engines or for vehicle transmissions.

The base oils of the lubricating compositions according to the invention may also be chosen from synthetic oils, such as certain carboxylic acid esters and alcohols, as well as from polyalphaolefins. The polyalphaolefins used as base oils are, for example, obtained from monomers comprising from 4 to 32 carbon atoms, for example from octene or decene, and whose viscosity at 100 ° C. is between 1, 5 and 15 mm ² . s ^"1 according to the ASTM D445 standard, their average molecular weight is generally between 250 and 3000 according to the ASTM D5296 standard. Advantageously according to the invention, the base oil can be chosen from Group III oils, Group IV oils and Group V oils. Advantageously, the lubricating composition according to the invention can comprise at least 50% by weight of base oils relative to the total mass of the composition. More advantageously, the lubricant composition according to the invention may comprise at least 60% by weight, or even at least 70% by weight, of base oils relative to the total mass of the composition. More particularly advantageously, the lubricant composition according to the invention may comprise from 50, 60 or 70 to 99.9% by weight, or 50, 60 or 70 to 90% by weight, of one or more base oils. relative to the total mass of the composition.

The lubricating composition according to the invention may also comprise at least one additional additive. Many additional additives can be used for the lubricant composition according to the invention. The additional additives preferred for the lubricating composition according to the invention are chosen from detergent additives, antiwear additives different from the compounds of formula (I), friction modifying additives, extreme pressure additives, dispersants, improvers and pour point, defoamers, thickeners and mixtures thereof.

Preferably, the lubricating composition according to the invention comprises at least one organic friction modifier chosen from esters, preferably from mono-esters of polyols, more preferably chosen from glycerol mono-esters. More preferably, the organic friction modifier is chosen from the glycerol mono-esters obtained by esterification reaction between glycerol and a saturated or unsaturated carboxylic acid comprising at least 10 carbon atoms, preferably from 10 to 20 atoms. carbon, more preferably from 15 to 20 carbon atoms, preferably from 15 to 18 carbon atoms. As an example of organic friction modifiers according to the invention, mention may be made of glycerol mono-oleate.

Preferably, the lubricating composition according to the invention comprises from 0.1 to 2% by weight, preferably from 0.1 to 1.5% by weight, more preferably from 0.5 to 1.5% by weight of modifiers. of organic friction. There is a wide variety of additional anti-wear additives different from the compounds of formula (I).

Amine phosphates are also anti-wear additives which can be used in the lubricating composition according to the invention. However, the phosphorus provided by these additives can act as a poison of the catalytic systems of automobiles because these additives are ash generators. These effects can be minimized by partially substituting amine phosphates with non-phosphorus additives, such as, for example, polysulfides, especially sulfur-containing olefins. Advantageously, the lubricant composition according to the invention may comprise from 0.01 to 6% by weight, preferably from 0.05 to 4% by weight, more preferably from 0.1 to 2% by weight relative to the mass. total lubricating composition, additional anti-wear additives. The lubricating composition according to the invention may comprise at least one inorganic friction modifier additive. The inorganic friction modifier additive may be selected from a compound providing metal elements and an ash free compound. Among the compounds providing metal elements, mention may be made of transition metal complexes such as Mo, Sb, Sn, Fe, Cu and Zn, the ligands of which may be hydrocarbon compounds comprising oxygen, nitrogen, sulfur or phosphorus.

Advantageously, the lubricant composition according to the invention may comprise at least one antioxidant additive. The antioxidant additive generally serves to retard the degradation of the lubricating 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 lubricant composition.

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

Preferably, according to the invention, the sterically hindered phenols are chosen from compounds comprising a phenol group in which at least one vicinal carbon of the carbon bearing the alcohol function is substituted with at least one alkyl group containing ₁₀ carbon atoms, preferably an alkyl group containing CrC ₆ , preferably a C ₄ alkyl group, preferably by the ter-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 formula NR ^a R ^b R ^c wherein R ^a represents an optionally substituted aliphatic or aromatic group, R ^b represents an aromatic group, optionally substituted, R ^c represents a hydrogen atom, an alkyl group, an aryl group or a group of formula R ^d S (0) _z R ^e in which R ^d represents an alkylene group or an alkenylene group, R ^e represents an alkyl group, 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 copper compounds, for example copper thio- or dithio-phosphates, copper and carboxylic acid salts, dithiocarbamates, sulphonates, phenates, copper acetylacetonates. Copper salts I and II, succinic acid or anhydride salts can also be used.

The lubricant composition according to the invention may contain all types of antioxidant additives known to those skilled in the art.

Also advantageously, the lubricating composition according to the invention comprises from 0.5 to 2% by weight relative to the total weight of the composition, of at least one antioxidant additive.

The lubricant composition according to the invention may also comprise at least one detergent additive. The detergent additives generally make it possible to reduce the formation of deposits on the surface of the metal parts by dissolving the secondary oxidation and combustion products. The detergent additives that may be used in the lubricant composition according to the invention may be anionic compounds comprising a long lipophilic hydrocarbon chain and a hydrophilic head. The associated cation may be a metal cation of an alkali metal or alkaline earth metal. The detergent additives are preferably chosen from the alkali metal or alkaline earth metal salts of carboxylic acids, the sulphonates, the salicylates, the naphthenates and the phenate salts. The alkali and alkaline earth metals are preferably calcium, magnesium, sodium or barium. These metal salts generally comprise the metal in stoichiometric amount or in excess, therefore in an amount greater than the stoichiometric amount. It is then overbased detergent additives; the excess metal bringing the overbased character to the detergent additive is then generally in the form of an oil insoluble metal salt, for example a carbonate, a hydroxide, an oxalate, an acetate, a glutamate, preferably a carbonate .

Advantageously, the lubricant composition according to the invention may comprise from 2 to 4% by weight of detergent additive relative to the total mass of the lubricating composition.

Also advantageously, the lubricant composition according to the invention may also comprise at least one pour point depressant additive.

By slowing the formation of paraffin crystals, pour point depressant additives generally improve the cold behavior of the lubricant composition according to the invention.

As examples of pour point depressant additives, mention may be made of alkyl polymethacrylates, polyacrylates, polyarylamides, polyalkylphenols, polyalkylnaphthalenes and alkylated polystyrenes.

Advantageously, the lubricant composition according to the invention may also comprise at least one dispersing agent. The dispersing agent may be chosen from Mannich bases, succinimides and their derivatives.

Also advantageously, the lubricating composition according to the invention may comprise from 0.2 to 10% by weight of dispersing agent relative to the total mass of the lubricating composition.

Advantageously, the lubricating composition may also comprise at least one viscosity index improving polymer. As examples of an improving polymer the viscosity number include polymeric esters, homopolymers or copolymers, hydrogenated or non-hydrogenated, styrene, butadiene and isoprene, polymethacrylates (PMA).

Also advantageously, the lubricating composition according to the invention may comprise from 1 to 15% by weight relative to the total weight of the viscosity index improving lubricant composition.

Preferably, the lubricating composition according to the invention is used for lubricating an engine, preferably a vehicle, more preferably a motor vehicle.

Thus, the present invention also relates to the use of a lubricant composition according to the invention for lubricating an engine, preferably a vehicle, more preferably a motor vehicle.

More preferably, the present invention also relates to the use of a lubricant composition according to the invention for lubricating a vehicle engine, more preferably a motor vehicle.

The present invention also relates to a method of lubricating a motor vehicle, preferably motor vehicle, comprising at least one step of contacting said motor with the lubricant composition according to the invention.

The present invention also relates to the use of a compound of formula (I) for improving the anti-wear properties of a lubricating composition comprising an oil selected from PAG. The set of characteristics and preferences relating to the compound of formula (I) and to the PAG described above applies to this use.

The present invention will now be illustrated by means of non-limiting examples. Example 1: Lubricating compositions according to the invention

Lubricating compositions according to the invention are prepared according to Table 1 below (the compositions are given by weight (g)).

In the compositions below: PAG 1: PAG comprising propylene oxide and butylene oxide units and an OH terminus (corresponding to formula (IV) with p ~ 2.8 and q ~ 2.2)

PAG 2: PAG comprising propylene oxide and butylene oxide units and a -OCH ₃ terminus (corresponding to formula (VI) with s ~ 3.5 and t ~ 2.8)

- Anti-wear 1 (Lubrizol 1371® sold by LUBRIZOL): a mixture of compound of formula (I) in which R1 and R2 represent a dimethyl butyl group and of compound of formula (I) in which R1 and R2 represent a grouping isopropyl

- Anti-wear 2 (RC3045® marketed by RheinChemie): a mixture of compound of formula (I) in which R1 and R2 represent a pentyl group and of compound of formula (I) in which R1 and R2 represent a butyl group

- Anti-wear 3 (KT2203® marketed by Kangtai Lubricant Additives): compound of formula (I) in which R1 and R2 represent a primary C-8 alkyl group

- Friction modifier 1: glycerol mono-oleate

Friction modifier 2 (Sakuralube 525® marketed by the company Adeka): molybdenum dithiocarbamate

Table 1

Example 2: Evaluation of the anti-wear properties

This assessment is based on a procedure based on ASTM D2670 requiring the use of a FALEX tribometer and whose test conditions are described below.

- test pieces: FALEX steel - Break-in time: 300 s

- Test duration: 180 min

- Break-in charge: 445 N

- Test load: 1335 N

- Speed: 290 rpm

- Ambient temperature

The results are presented in Table 2 and are expressed in μηι; the lower the value obtained, the better the anti-wear properties of the evaluated composition

Table 2

The results show that the lubricant compositions according to the invention (compositions 1, 2, 3 and 4) have improved anti-wear properties compared to comparative lubricating compositions (comparative compositions 1 and 2).

Claims

1. Lubricating composition comprising 1 to 99.5% by weight of an oil chosen from polyalkylated glycols (PAG or polyalkylene glycols) and an anti-wear additive chosen from compounds of formula (I)

(I)

2. Composition according to claim 1 wherein the PAG is a block polymer of formula (II) or a random polymer of formula (II)

in which

^■ R3 represents a group CC ₃₀ linear or branched alkyl, preferably a C ₄ -C ₁₂ linear alkyl group or branched;

^■ n is a number from 2 to 60, preferably from 5 to 30 or 7 to 15;

^■ R4 and R5, identical or different, independently represent a hydrogen atom or a C ₂ alkyl group.

3. Composition according to claim 1 or 2 for which the PAG is chosen from

a block polymer of formula (IIA) or a random polymer of formula (MA)

(IIA)

in which ^■ R3 represents a group CC ₃₀ linear or branched alkyl, preferably a C ₄ -C ₁₂ linear alkyl group or branched;

^■ m is a number from 2 to 60, preferably from 5 to 30 or 7 to 15;

^■ R6 and R7 represent a hydrogen atom; or R6 represents a hydrogen atom and R7 represents a methyl group; or R6 represents a methyl group and R7 represents a hydrogen atom; or R6 and R7 represent a methyl group; or R6 represents an ethyl group and R7 represents a hydrogen atom; or R6 represents a hydrogen atom and R7 represents an ethyl group;

a block polymer of formula (MB) or a random polymer of formula (MB)

(MB)

in which

^■ R 3 is a C ₃₀ linear alkyl group or branched, preferably a C ₂ -C ₄ linear or branched alkyl, more preferably a C ₈ -C ₂ alkyl linear or branched;

^■ p and q are independently a number ranging from 1 to 30, preferably from 2 to 15 or 2 to 8;

^■ R8 and R9 represent a hydrogen atom; or R8 represents a hydrogen atom and R9 represents a methyl group; or R8 represents a methyl group and R9 represents a hydrogen atom; or R8 and R9 represent a methyl group; or R8 represents an ethyl group and R9 represents a hydrogen atom; or R8 represents a hydrogen atom and R9 represents an ethyl group;

^■ R10 and R1 1 represents a hydrogen atom; or R10 represents a hydrogen atom and R1 1 represents a methyl group; or R10 represents a methyl group and R1 1 represents a hydrogen atom; or R10 and R1 1 represent a methyl group; or R10 represents an ethyl group and R1 1 represents a hydrogen atom; or R10 represents a hydrogen atom and R1 1 represents an ethyl group.

4. Composition according to one of claims 1 to 3 wherein the PAG is selected from - a block polymer of formula (III) or a random polymer of formula (III) in which

^■ p represents a number from 1 to 30, preferably from 2 to 15 or 2 to 8;

^■ q is a number from 1 to 30, preferably from 1 to 10, or a block polymer of formula (IV) or a random polymer of formula (IV)

(IV)

in which

^■ R 3 is a C ₈ -C ₁₂ linear or branched alkyl;

^■ p represents a number from 2 to 6;

^■ q represents a number ranging from 2 to 5.

a block polymer of formula V) or a random polymer of formula (V)

(V)

in which

^■ r is a number from 2 to 60, preferably from 5 to 30 or 7 to 15.

5. Composition according to claim 1 wherein the PAG is a block polymer of formula (VI) or a random polymer of formula (VI)

(VI)

in which

R 12 is a C ₃₀ linear alkyl group or branched, preferably a C ₈ -C ₅ linear or branched alkyl;

^■ s and t independently represent an average number ranging from 1 to 5.

6. Composition according to one of claims 1 to 5 comprising 1 to 99.5% by weight of PAG.

7. Composition according to any one of claims 1 to 6 comprising from 1 to 30%, preferably from 1 to 20%, more preferably from 1 to 15% by weight of PAG.

8. Composition according to any one of claims 1 to 6 comprising from 40 to 99.5%, preferably from 50 to 99.5%, more preferably from 70 to 99.5% by weight of PAG.

9. Composition according to any one of claims 1 to 6 comprising from 5 to 80%, preferably from 10 to 80%, for example from 10 to 70%, for example from 20 to 60%, preferably from 30 to 50%. % by weight of PAG.

10. Composition according to one of claims 1 to 9 wherein the antiwear additive is selected from compounds of formula (I)

(I)

in which R1 and R2, identical or different, represent a secondary C3-alkyl group or a secondary C6-alkyl group.

1 1. Composition according to one of claims 1 to 10 comprising from 0.1 to 3%, preferably from 0.1 to 2%, more preferably from 0.1 to 1% by weight of compound of formula (I).

12. Composition according to one of claims 1 to 1 1 comprising a lubricating base oil.

13. Composition according to one of claims 1 to 12 further comprising an organic friction modifier selected from esters, preferably from mono-esters of polyols, more preferably selected from mono-esters of glycerol.

14. Use of a lubricant composition according to one of claims 1 to 13 for the lubrication of a vehicle engine, preferably a motor vehicle.