This application relates to the field of lubricant compositions, including lubricating compositions for motor vehicles, particularly for motor vehicle mloteur. In particular, the present application relates to lubricating compositions based on polyalkyl glycols (PAG or polyalkylene glycols) to the
engine lubricating vehicle, in particular motor vehicle.
Energy efficiency and automotive engine fuel consumption reduction is a growing concern. It is known that lubricants for engines used in these vehicles have an important role in this regard.

To formulate lubricants "Fuel Eco" or fuel savers, it is known to play on the viscosity of the base oil used. It is also known to use polymers improvers viscosity index (VI), or use of friction modifiers. However, improving polymers the viscosity index have the disadvantage of degrading the engine cleanliness of the lubricant compositions in which they are employed. But today's engines have high thermal stresses that result in significant deposition phenomena. The deposits are associated with the chemical transformation of the lubricant in the nearest of the combustion chamber and therefore the hottest parts.

Lubricating compositions "Fuel-Eco" based on polyalkyl glycols (PAG or polyalkylene glycols) have been described in WO 2013/164449, said compositions also having good engine cleanliness properties.

However, the use of the PAG can sometimes lead to increased wear of mechanical parts of the engine, and thus degradation of durability of said motor.

There is therefore an interest in providing a lubricating composition including a lubricating composition dre 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, particularly a lubricant composition based PAG for motor vehicle engines, having improved antiwear properties.

Another object of the present invention is to provide a lubricant composition based on PAG, particularly a lubricating composition PAG-based vehicle engine

automobile, having both anti-wear properties and improved "Fuel-Eco" properties satisfactory.

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

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

Another object of the invention is to provide a lubricant composition based on PAG, particularly a lubricant composition based PAG for a motor vehicle engine, having improved antiwear properties and easy to formulate.

To meet the above objectives and the drawbacks mentioned in the prior art, the present invention provides a lubricating composition comprising:

- an oil selected from polyalkyl glycols (PAG or polyalkylene glycols), and

- a nitrogen-containing compound selected from amine phosphates or amine tungstates.

Particularly advantageously, the lubricant composition of the present invention is a lubricating composition for the engine, preferably vehicle, more preferably of a motor vehicle.

The nitrogen compound of the invention may be selected from amine phosphates and preferably composition further comprises a friction modifier selected from organomolydène compounds, preferably selected from molybdenum dithiocarbamates and their derivatives.

Preferably, the nitrogen compound of the invention is a phosphate selected from amine

• the compounds of formula (IA)

(IA)

in which :

- R1 represents a linear or branched alkyl group comprising from 2 to 10 carbon atoms, preferably from 3 to 9 carbon atoms, more preferably from 5 to 8 carbon atoms;

- R2 represents a linear or branched alkyl group comprising from 8 to 15 carbon atoms, preferably from 9 to 14 carbon atoms, more preferably from 10 to 14 carbon atoms;

• the compounds of formula (IB)

(IB)

in which :

- R1 represents a linear or branched alkyl group comprising from 2 to 10 carbon atoms, preferably from 3 to 9 carbon atoms, more preferably from 5 to 8 carbon atoms;

- R2 represents a linear or branched alkyl group comprising from 8 to 15 carbon atoms, preferably from 9 to 14 carbon atoms, more preferably from 10 to 14 carbon atoms;

• a mixture of at least one compound of formula (IA) and at least one compound of formula (IB)

More preferably, the nitrogen compound of the invention is a phosphate selected from amine

• the compounds of formula (IA)

(HE)

in which

- R1 represents a linear alkyl group comprising from 2 to 10 carbon atoms, preferably from 3 to 9 carbon atoms, more preferably from 5 to 8 carbon atoms;

- R2 represents a linear or branched alkyl group comprising from 8 to 15 carbon atoms, preferably from 9 to 14 carbon atoms, more preferably from 10 to 14 carbon atoms;

• the compounds of formula (IB)

(IB)

in which :

- R1 represents a linear alkyl group comprising from 2 to 10 carbon atoms, preferably from 3 to 9 carbon atoms, more preferably from 5 to 8 carbon atoms;

- R2 represents a linear or branched alkyl group comprising from 8 to 15 carbon atoms, preferably from 9 to 14 carbon atoms, more preferably from 10 to 14 carbon atoms;

• a mixture of at least one compound of formula (IA) and at least one compound of formula (IB)

Also more preferably, the nitrogen compound of the invention is a phosphate selected from amine

• the compounds of formula (IA)

(HE)

in which :

- R1 represents a branched alkyl group comprising from 2 to 10 carbon atoms, preferably from 3 to 9 carbon atoms, more preferably from 5 to 8 carbon atoms;

- R2 represents a linear or branched alkyl group comprising from 8 to 15 carbon atoms, preferably from 9 to 14 carbon atoms, more preferably from 10 to 14 carbon atoms;

• the compounds of formula (IB)

(IB)

in which :

- R1 represents a branched alkyl group comprising from 2 to 10 carbon atoms, preferably from 3 to 9 carbon atoms, more preferably from 5 to 8 carbon atoms;

- R2 represents a linear or branched alkyl group comprising from 8 to 15 carbon atoms, preferably from 9 to 14 carbon atoms, more preferably from 10 to 14 carbon atoms;

• a mixture of at least one compound of formula (IA) and at least one compound of formula (IB)

Also more preferably, the nitrogen compound of the invention is a phosphate selected from amine

• the compounds of formula (IA)

(HE)

in which :

- R1 represents a linear or branched alkyl group comprising from 2 to 10 carbon atoms, preferably from 3 to 8 carbon atoms, more preferably from 4 to 7 carbon atoms;

- R2 represents a linear alkyl group comprising from 8 to 15 carbon atoms, preferably from 9 to 14 carbon atoms, more preferably from 10 to 14 carbon atoms;

• the compounds of formula (IB)

(IB)

in which :

- R1 represents a linear or branched alkyl group comprising from 2 to 10 carbon atoms, preferably from 3 to 8 carbon atoms, more preferably from 4 to 7 carbon atoms;

- R2 represents a linear alkyl group comprising from 8 to 15 carbon atoms, preferably from 9 to 14 carbon atoms, more preferably from 10 to 14 carbon atoms;

"A mixture of at least one compound of formula (IA) and at least one compound of formula (IB)

Also more preferably, the nitrogen compound of the invention is a phosphate selected from amine

• the compounds of formula (IA)

(HE)

in which :

- R1 represents a linear or branched alkyl group comprising from 2 to 10 carbon atoms, preferably from 3 to 8 carbon atoms, more preferably from 4 to 7 carbon atoms;

- R2 represents a branched alkyl group containing from 8 to 15 carbon atoms, preferably from 9 to 14 carbon atoms, more preferably from 10 to 14 carbon atoms;

• the compounds of formula (IB)

in which :

- R1 represents a linear or branched alkyl group comprising from 2 to 10 carbon atoms, preferably from 3 to 8 carbon atoms, more preferably from 4 to 7 carbon atoms;

- R2 represents a branched alkyl group containing from 8 to 15 carbon atoms, preferably from 9 to 14 carbon atoms, more preferably from 10 to 14 carbon atoms;

• a mixture of at least one compound of formula (IA) and at least one compound of formula (IB)

Advantageously, the nitrogen compound is a mixture of at least one compound of fomrule (IA) and at least one compound of formula (IB) in which:

- R1 is a hexyl or ethylhexyl group,

- R2 represents a linear or branched alkyl group comprising from 1 1 to 14 volumes atoms, preferably a linear C13-alkyl group or branched.

The nitrogen compound of the invention may be selected from amine tungstates.

amine tungstates according to the invention and their method of preparation are described in International patent application WO-2008/1 16099 or in International patent application WO-2013/077 948.

Also preferably, the nitrogen-containing compound according to the invention is selected from:

- amine tungstates obtained from at least one fatty amine comprising at least one linear alkyl group comprising from 8 to 15 carbon atoms, preferably from 9 to 14 carbon atoms, more preferably from 10 to 14 carbon atoms ,

- amine tungstates obtained from at least one fatty amine comprising at least one branched alkyl group comprising from 8 to 15 carbon atoms, preferably from 9 to 14 carbon atoms, more preferably from 10 to 14 carbon atoms ,

- a mixture of at least one amine tungstate obtained from at least one fatty amine comprising at least one linear alkyl group comprising from 8 to 15 carbon atoms, preferably from 9 to 14 carbon atoms, more preferably from 10 to 14 carbon atoms and an amine tungstate obtained from at least one fatty amine comprising at least one branched alkyl group comprising from 8 to 15

carbon atoms, preferably from 9 to 14 carbon atoms, more preferably from 10 to 14 carbon atoms.

More preferably, the nitrogen compound is a mixture of at least one amine tungstate obtained from at least one fatty amine comprising at least one linear alkyl group comprising from 1 1 to 14 carbon atoms, preferably a group linear or branched C13-alkyl and an amine tungstate obtained from at least one fatty amine comprising at least one branched alkyl group comprising from 1 1 to 14 carbon atoms, preferably a linear C13-alkyl group or branched .

Examples of nitrogen-containing compounds according to the invention include the product Irgalube 349 marketed by BASF or product Vanlube W-324® sold by the Vanderbilt company.

Preferably, the lubricating composition according to the invention comprises from 0.1 to 3%, preferably from 0.1 to 2%, more preferably from 0.4 to 1, 5% by weight of nitrogen compound.

According to the invention, the PAG of the lubricating composition according to the invention can be a block polymer or a random polymer.

The PAG of the invention includes alkyl groups in which the length of hydrocarbon chains can vary. According to the invention, the length of hydrocarbon chains is defined by an average 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

■ R3 represents a group CC 30 linear or branched alkyl, preferably a group C 4 -C 12 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 group -C 2 -alkyl.

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

In a preferred PAG of the invention, R3 represents a group C 4 -C 12 linear or branched alkyl, R4 and R5 are different and independently represent a hydrogen atom or a group -C 2 linear alkyl and n is a number 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

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

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

■ R 6 and R 7 represent a hydrogen atom; or R6 is hydrogen and R7 is methyl; or R6 is methyl and R7 is hydrogen; or R6 and R7 represent a methyl group; or R6 is ethyl and R7 is hydrogen; or R6 is hydrogen and R7 is ethyl.

For the PAG of the invention, m can be a number from 2 to 60, preferably ranging from 5 to 30 or 7 to 15.

In a preferred PAG of the invention, R3 is C 4 -C 2 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 from 7 to 15.

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

(MB)

in which

■ R3 represents a group CC 30 linear or branched alkyl, preferably a group C 4 -C 12 linear or branched alkyl, more preferably a C 8 -C 12 linear or branched alkyl;

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

■ R 8 and R 9 represent a hydrogen atom; or R8 is hydrogen and R9 is methyl; or R8 is methyl and R9 is hydrogen; or R8 and R9 are methyl; or R8 is ethyl and R9 is hydrogen; or R8 is hydrogen and R9 is ethyl;

■ R10 and R1 1 represents a hydrogen atom; or R10 represents a hydrogen atom and R1 1 represents a methyl group; or R10 is methyl and R1 1 is hydrogen; or R10 and R1 1 are methyl; or R10 is ethyl and R1 1 represents a hydrogen atom; or R10 represents a hydrogen atom and R1 1 is ethyl.

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

As individuals PAG of the invention include

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

■ PAG for which R8 and R10 represent a hydrogen atom and R9 and R1 1 are methyl; or

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

In a preferred PAG of the invention, R3 is C 4 -C 2 linear or branched alkyl, R8, R10 and R1 1 represents a hydrogen atom and R9 represents a methyl group, p represents a number ranging from 3 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, R 3 is a C 8 -C 2 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 from 3 to 8, for example 5, and q represents a number 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 in the range SYNALOX 50-B® marketed by Dow Chemical.

More 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 8 -C 2 linear or branched alkyl;

■ p represents a number from 2 to 6;

■ q is a number from 2 to 5.

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

More 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

■ R 3 is a C 4 -C 2 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.

Examples of PAG of formula (V) include the products in the range SYNALOX 100-B® marketed by Dow Chemical.

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

(WE)

in which

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

■ s and t are independently an average number from 1 to 5.

In a preferred PAG of the invention, R12 represents a group selected from a C 8 linear alkyl; a C 8 alkyl branched; a C 9 linear alkyl; a C 9 alkyl branched; a linear Cio-alkyl group; Cio-alkyl branched; a linear Cn-alkyl group; a Cn-alkyl group branched; a group The two linear alkyl; a group Ci 2 alkyl branched; a C group 3 linear alkyl; a C 3 alkyl branched; a C group 4 linear alkyl; a group C 14 alkyl branched; a C 15 linear alkyl; a C 15 alkyl branched.

In a preferred PAG of the invention:

■ s is greater than or equal to t; or

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

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

In a preferred PAG of the invention:

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

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

In a preferred PAG of the invention:

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

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

In a preferred PAG of 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 below -40 ° C; or whose

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

PAG of processes for preparing of formula (VI) are described in WO-2016/016 362.

Preferably, the lubricating composition according to the invention comprises from 1 to 99.5% by weight of PAG.

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

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

Alternatively more preferably, the lubricant composition according to the invention comprises 40 to 99.5%, preferably from 50 to 99.5% more preferably from 60 to 99.5%, more preferably from 70 to 99, 5%, preferably from 80 to 99.5% by weight of PAG.

Furthermore a PAG and a nitrogen compound selected from amine phosphates or amine tungstates, the lubricating composition according to the invention may comprise a base oil.

Generally, 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 lubricating compositions of the invention may 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 classification ATIEL) (Table A ) or mixtures thereof.

Preferably, the base oil is different from the PAG.

Table A

The mineral base oils that may be used for the lubricant composition of the invention include all types of bases obtained by atmospheric and vacuum distillation of crude oil, followed by refining operations such as extraction solvent, désalphatage, dewaxing solvent, 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 realize the lubricating compositions according to the invention, except that they must have properties, including viscosity, viscosity index, sulfur and resistance to oxidation, particularly suitable for use in engines or for vehicle transmissions.

Base oils of lubricating compositions according to the invention may also be chosen from synthetic oils such certain esters of carboxylic acids and alcohols as well as from polyalphaolefins. 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 having a viscosity at 100 ° C is between 1, 5 and 15 mm 2 . s "1 in accordance with ASTM D445. The average molecular mass is generally between 250 and 3000 according to the ASTM D5296 standard.

Advantageously according to the invention, the base oil may be selected from the Group III oils, Group IV oils and oils of the group V.

Advantageously, the lubricating composition according to the invention may comprise at least 50% by weight of base oils relative to the total weight of the composition. More advantageously, the lubricating composition according to the invention may comprise at least 60% by weight, or even at least 70 wt%, base oil based on the total weight of the composition. Of more advantageously, the lubricating composition according to the invention may comprise 50, 60 or 70 to 99.9% by mass, or 50, 60 or 70 to 90% by weight, of one or more base oils relative to the total weight of the composition.

The lubricating composition according to the invention may also comprise at least one additional additive. Many additives can be used for the lubricant composition according to the invention. Preferred additional additives for the lubricant composition according to the invention are selected from detergent additives, the various anti-wear additives of the compounds selected from amine phosphates or amine tungstates, friction modifiers additives, extreme additives pressure, dispersants, pour point improvers to, antifoaming agents, thickeners and mixtures thereof.

Preferably, the lubricating composition according to the invention comprises at least an inorganic friction modifier selected from organomolybdenum compounds, preferably among molybdenum dithiocarbamates and their derivatives.

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 modifier inorganic friction.

There are a wide variety of additional antiwear additives different from the compounds selected from amine phosphates or amine tungstates.

Additional anti-wear additives may be selected from phospho-sulfurized additives such as metal alkylthiophosphates, especially zinc alkylthiophosphates, more specifically zinc dialkyldithiophosphates or ZnDTP. Preferred compounds are of the formula Zn ((SP (S) (OR 13 ) (OR 14 )) 2 , wherein R 13 and R 14 , identical or different, independently represent an alkyl, preferably an alkyl group having from 1 to 18 carbon atoms.

Advantageously, the lubricating 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 mass relative to the mass total lubricant composition, of additional anti-wear additives.

The lubricating composition according to the invention may comprise at least one organic friction modifier additive. The organic friction modifier additive can be selected from monoesters of fatty acids and of polyols, alkoxylated amines, alkoxylated fatty amines, fatty epoxides, borated fatty epoxides; fatty amines or fatty acid glycerol esters. According to the invention, the fatty compounds comprise at least one hydrocarbon group having from 10 to 24 carbon atoms.

Advantageously, the lubricating composition according to the invention may comprise at least one antioxidant additive. The antioxidant additive generally used to delay the degradation of the lubricating composition in service. This degradation may especially result in the formation of deposits, the presence of sludge or by increasing the viscosity of the lubricant composition.

Antioxidant additives such act as free radical inhibitors or destructive hydroperoxides. Among the additives commonly used antioxidants include phenolic antioxidants additives type additives amine antioxidants, antioxidants additives phosphorosulphur. Some of these antioxidant additives, such as antioxidants phosphorosulphur additives may be ash generators. Additives phenolic antioxidants may be ashless or be in the form of neutral or basic metal salts. Antioxidant additives may be chosen from sterically hindered phenols, sterically hindered phenol esters and hindered phenols comprising a thioether bridge, the diphenylamines, the substituted diphenylamines at least one alkyl group -C 12 , the Ν, Ν ' -dialkyle-aryl diamines and mixtures thereof.

Preferably according to the invention, sterically hindered phenols are selected from compounds comprising a phenol group in which at least one carbon vicinal carbon bearing the alcohol function is substituted by at least one alkyl group dC 1 0, preferably an alkyl group -C 6 , preferably an alkyl group C 4 , preferably by tert-butyl group.

Amine compounds are another class of antioxidant additives that can be used, optionally in combination with additives phenolic antioxidants. Examples of amino compounds are aromatic amines, for example, aromatic amines of the formula NR a R b R c wherein R a represents an aliphatic group or an aromatic group, optionally substituted, 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 may also be used as antioxidant additives.

Another antioxidant additives class is that of copper compounds, for examples thio- or dithio-phosphates of copper, copper salts of carboxylic acids, dithiocarbamates, sulphonates, phenates, copper acetylacetonates. Copper salts I and II, acid salts or succinic anhydride can also be used.

The lubricating composition according to the invention can contain all types of additives antioxidants 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 lubricating composition according to the invention may also comprise at least one detergent additive. The detergent additives generally reduce the formation of deposits on the surface of metal parts by dissolution of secondary oxidation and combustion products.

The detergent additives used in the lubricant composition according to the invention may be anionic compounds comprising a lipophilic long 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 selected from alkali metal salts or alkaline earth metal salts of carboxylic acids, sulfonates, salicylates, naphthenates, phenates and the salts. Alkali and alkaline earth metals are preferably calcium, magnesium, sodium or barium. These metal salts generally include the metal in stoichiometric amount or in excess, so in excess of the stoichiometric amount. It is then overbased detergents additives; excess metal providing the character to the overbased detergent additive is then usually in the form of an insoluble metal salt in the oil, for example a carbonate, hydroxide, oxalate, acetate, glutamate, preferably a carbonate .

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

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

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

Examples of additives of pour point depressants include alkyl polymethacrylates, polyacrylates, polyarylamides, the polyalkylphenols, the polyalkylnaphthalenes, alkylated polystyrenes.

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

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 weight of the lubricating composition.

Advantageously, the lubricating composition may also comprise at least one polymer improving the viscosity index. Examples of polymeric viscosity index improver, there may be mentioned ester polymers, homopolymers or copolymers, hydrogenated or non-hydrogenated, styrene, butadiene and isoprene, polymethacrylates (PMA).

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

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

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

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

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

The present invention also relates to the use of a nitrogen compound selected from amine phosphates or amine tungstates to improve antiwear properties of a lubricating composition comprising an oil selected from the PAG.

The set of characteristics and preferences for nitrogen compound and PAG described above applies to such use.

The present invention will now be illustrated with 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:

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

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

- PAG 3 (SYNALOX 50-15B® sold by the company DOW CHEMICAL): PAG based on ethylene oxide units and propylene oxide units

- PAG 4 (SYNALOX 100-20B® sold by the company DOW CHEMICAL): PAG based on propylene oxide units

- 5 PAG: PAG comprising propylene oxide units and butylene oxide and an -OH terminus (corresponding to formula (IV) with p and q ~ 5 ~ 4)

- nitrogen-containing compound 1 (Irgalube 349® marketed by BASF): a mixture of compound of formula (IA) and compound of formula (IB) wherein R1 is a hexyl or ethylhexyl group and R2 represents an alkyl group comprising from 1 1 to 14 volumes atoms.

- nitrogen-containing compound 2 (Vanlube W-324® sold by the Vanderbilt company): mixture of at least one amine tungstate obtained from at least one fatty amine comprising at least one linear alkyl group comprising from 1 1 to 14 carbon atoms and an amine tungstate obtained from at least one fatty amine comprising at least one branched alkyl group comprising from 1 1 to 14 carbon atoms

- Friction Modifier (Sakuralube 525® marketed by Adeka Corporation): molybdenum dithiocarbamate

- Base oil (Yubase 4 + ® sold by the company SK) Group III base oil (kinematic viscosity 4.1 mm 2 / s measured at 100 ° C according to ASTM D445)

- Polymer 1 (Viscoplex 6-565® marketed by Evonik): polymethacrylate

- Polymer 2 (SV203® sold by the company Infineum): polyisoprene / hydrogenated styrene (pish)

- additive package: dispersant of succinimide type antiwear type dithiophosphate, calcium salicylate detergent, phenolic antioxidant, diphenylamine antioxidant of the type

Table 1

Example 2: Evaluation of anti-wear properties

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

- specimens: Steel FALEX

- running time: 300 s

- Test Time: 180 min

- lapping load: 445 N

- Test load: 1335 N

- Speed: 290 rev / min

- Ambient temperature

The results are presented in Table 2 and are expressed in μηι; the higher the value obtained is low, the better the anti-wear properties of the composition evaluated Composition 1 2 3 4 5 6 7 8

total wear (μηι) 28 24 24 38 24 18 44 28

Table 2

The results show that the lubricating compositions according to the invention (compositions 1-8) have good anti-wear properties.

It should be noted that improved anti-wear properties is actually obtained - in the presence or absence of additional base oils

- in the presence or absence of further additives.

CLAIMS
1. A lubricating composition comprising an oil selected from polyalkyl glycols (PAG or polyalkylene glycols) and a nitrogen compound selected from amine tungstates or amine phosphates.

2. The composition of claim 1 wherein the nitrogen compound is selected from:

- amine tungstates obtained from at least one fatty amine comprising at least one linear alkyl group comprising from 8 to 15 carbon atoms, preferably from 9 to 14 carbon atoms, more preferably from 10 to 14 carbon atoms ,

- amine tungstates obtained from at least one fatty amine comprising at least one branched alkyl group comprising from 8 to 15 carbon atoms, preferably from 9 to 14 carbon atoms, more preferably from 10 to 14 carbon atoms ,

- a mixture of at least one amine tungstate obtained from at least one fatty amine comprising at least one linear alkyl group comprising from 8 to 15 carbon atoms, preferably from 9 to 14 carbon atoms, more preferably from 10 to 14 carbon atoms and an amine tungstate obtained from at least one fatty amine comprising at least one branched alkyl group comprising from 8 to 15 carbon atoms, preferably from 9 to 14 carbon atoms, more preferably from 10 to 14 carbon atoms.

3. The composition of claim 1 wherein the nitrogen compound is an amine phosphate and further comprising a friction modifier selected from organomolydène compounds, preferably selected from molybdenum dithiocarbamates and their derivatives.

4. Composition according to claim 1 or 2, wherein the nitrogen compound is selected from amine phosphate:

• the compounds of formula (IA)

(HE)

in which :

- R1 represents a linear or branched alkyl group comprising from 2 to 10 carbon atoms, preferably from 3 to 9 carbon atoms, more preferably from 5 to 8 carbon atoms;

- R2 represents a linear or branched alkyl group comprising from 8 to 15 carbon atoms, preferably from 9 to 14 carbon atoms, more preferably from 10 to 14 carbon atoms;

• the compounds of formula (IB)

O

II 2

*Rt—■ O— P— - OH H M

| V

o R2

I

RI

(IB)

in which :

R1 represents a linear or branched alkyl group comprising from 2 to 10 carbon atoms, preferably from 3 to 9 carbon atoms, more preferably from 5 to 8 carbon atoms;

- R2 represents a linear or branched alkyl group comprising from 8 to 15 carbon atoms, preferably from 9 to 14 carbon atoms, more preferably from 10 to 14 carbon atoms;

• a mixture of at least one compound of formula (IA) and at least one compound of formula (IB).

5. Composition according to one of claims 1 to 4 wherein the PAG is a block polymer of formula (II) or a random polymer of formula (II)

(the)

in which

■ R3 represents a group CC 30 linear or branched alkyl, preferably a group C 4 -C 12 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 group -C 2 -alkyl.

6. Composition according to one of claims 1 to 5 wherein the PAG is selected from o 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 group C 4 -C 12 linear or branched alkyl;

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

■ R 6 and R 7 represent a hydrogen atom; or R6 is hydrogen and R7 is methyl; or R6 is methyl and R7 is hydrogen; or R6 and R7 represent a methyl group; or R6 is ethyl and R7 is hydrogen; or R6 is hydrogen and R7 is ethyl;

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

(MB)

in which

■ R3 represents a group CC 30 linear or branched alkyl, preferably a group C 4 -C 12 linear or branched alkyl, more preferably a C 8 -C 12 linear or branched alkyl;

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

■ R 8 and R 9 represent a hydrogen atom; or R8 is hydrogen and R9 is methyl; or R8 is methyl and R9 is hydrogen; or R8 and R9

represent a methyl group; or R8 is ethyl and R9 is hydrogen; or R8 is hydrogen and R9 is ethyl;

■ R10 and R1 1 represents a hydrogen atom; or R10 represents a hydrogen atom and R1 1 represents a methyl group; or R10 is methyl and R1 1 is hydrogen; or R10 and R1 1 are methyl; or R10 is ethyl and R1 1 represents a hydrogen atom; or R10 represents a hydrogen atom and R1 1 is ethyl.

7. Composition according to one of claims 1 to 6 wherein the PAG is selected from - 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, or - a polymer block of formula (IV) or a random polymer of formula (IV)

(IV)

in which

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

■ p represents a number from 2 to 6;

■ q is a number from 2 to 5.

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

(V)

in which

■ R 3 is a C 4 -C 2 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.

8. Composition according to one of claims 1 to 4 wherein the PAG is a block polymer of formula (VI) or a random polymer of the formula (VI)

(WE)

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 are independently an average number from 1 to 5.

9. Composition according to one of claims 1 to 8 comprising from 1 to 99.5% by weight of PAG.

10. Composition according to any one of claims 1 to 9 comprising from 1 to 30%, preferably 1 to 20%, more preferably from 1 to 15% by weight of PAG.

January 1. Composition according to any one of claims 1 to 9 comprising from 40 to 99.5%, preferably from 50 to 99.5%, more preferably from 70 to 99.5% by weight of PAG.

12. Composition according to one of claims 1-1 1, further comprising 0.1 to 3%, preferably from 0.1 to 2%, more preferably from 0.4 to 1, 5% by weight of nitrogen compound.

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

14. Composition according to one of claims 1, 2 and 4 to 13 further comprising a friction modifier selected from organomolydène compounds, preferably selected from molybdenum dithiocarbamates and their derivatives.

15. Use of a lubricating composition according to one of claims 1 to 14 for the lubrication of an engine or for lubricating an automotive engine.