The present application relates to the field of lubricant compositions, more particularly the field of lubricant compositions for engines, in particular motor vehicle engine, and transmission to gear. More particularly, the present application relates to the field of lubricant compositions for transmission and gearing.

The lubricant compositions for transmission (eg gearboxes or bridge) or gear, including industrial gears, must meet many requirements, particularly related to driving comfort (perfect speed passage, silent march, trouble-free operation, high reliability ), the life of the assembly (reducing wear during cold passage, no deposits and high thermal stability, lubrication safety at high temperatures, stable viscosity position and no loss shear, long life) and the consideration of environmental aspects (lower fuel consumption, lubricant consumption reduction, low noise emission, easy removal). It s' These include requirements for lubricant compositions boxes of manual transmissions and axle gears. Regarding the requirements for oils automatic transmissions (ATF oils for automatic transmission fluids), they are very specific and particular concern great constancy of the friction coefficient for the duration of stay for a change of optimum speed, excellent aging stability for long drain intervals, good viscosity-temperature held to ensure proper functionality with a hot engine and a cold engine and sufficient sealing compatibility with various elastomers in transmissions of joints so that these do swell no, do not shrink and does not weaken. Otherwise,2 requires to develop products that reduce friction in gearboxes and differentials bridges. This reduction of friction in the gearbox and the differential bridge must be obtained for different operating conditions. These reductions in friction should concern the internal friction of the lubricant but also friction of the components of gearboxes and differentials bridges, especially metallic elements.

(Poly) alkyl methacrylate (PAMA) are conventionally used for their very good intake of viscosity index and yet have a low shear stability. In addition, PAMA are expensive.

Polyalphaolefins (PAO) are used as exhibit good shear stability, however their intake of viscosity index is small.

There is therefore an interest in providing a solution to have a good intake of viscosity and good shear stability.

An object of the present invention is therefore to provide a lubricant composition, especially for transmission and gearing having a compromise between viscosity index and shear stability.

Another object of the present invention is also to provide such a composition which has a viscosity stability as a function of the temperature, that is to say a good viscosity index.

Yet another object of the present invention is to provide such a composition for a gain of Fuel Eco.

Other goals become apparent on reading the description of the invention that follows.

These objectives are met by the present application which relates to a lubricating composition comprising:

- at least a base oil;

- at least one polyalkylene glycol (PAG), comprising at least 50% by weight of butylene oxide units and propylene oxide units, having a kinematic viscosity measured at 100 ° C according to ASTM D445 (2015), greater than or equal to 50 mm 2 / s, a kinematic viscosity, measured at 40 ° C according to ASTM D445 (2015), greater than or equal to 500 mm 2 / s, more preferably greater than or equal to 1000 mm 2 / s, and a viscosity index, measured according to ASTM D2270 (2012), greater than or equal to 160, preferably greater than or equal to 180, even more preferably greater than or equal to 200.

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

- at least a base oil;

- at least one polyalkylene glycol (PAG), comprising at least 50% by weight of butylene oxide units, and preferably comprising only oxide units of

butylene, having a kinematic viscosity measured at 100 ° C according to ASTM D445 (2015), greater than or equal to 50 mm 2 / s, a kinematic viscosity, measured at 40 ° C according to ASTM D445 (2015), higher or equal to 1000 mm 2 / s and a viscosity index, measured according to ASTM D2270 (2012), greater than or equal to 180.

There has to be understood in the context of the present invention, the base oil and PAG are separate compounds.

Preferably, the PAG of the invention comprises at least 80% by weight of butylene oxide units and propylene oxide units. Even more preferably, the PAG of the invention is a PAG with alkylene units are only butylene oxide units.

The PAG of the invention is therefore described as a PAG whose alkylene oxide units are selected from butylene oxide units and propylene oxide with at least 50% by weight, preferably at least 80% by weight, more preferably 100% by weight, of butylene oxide units.

According to a preferred embodiment, the PAG of the invention comprises 100% by weight of butylene oxide units.

Particularly advantageously, the PAG of the invention is soluble in the base oil, and advantageously regardless of the temperature.

Preferably the PAG is obtained by polymerization or copolymerization of butylene oxides. Including the PAG of the invention may be prepared according to methods known in particular described in US20120108482 and in particular by reacting one or more alcohols having 2 to 12 carbon atoms, including polyol, preferably diol, with butylene oxide and propylene oxide. The alcohols include diols and preferably 1, 2-propanediol. The butylene oxide may be selected from 1, 2-butylene oxide or 2,3-butylene oxide, preferably 1, 2-butylene oxide. In the case where the PAG comprises only butylene oxide units, the method described in US20120108482 is tailored to the unique implementation of butylene oxide.

According to one embodiment, the PAG is obtained by reacting one or more polyols containing 2 to 12 carbon atoms, preferably diol, with butylene oxides.

Preferably, the PAG of the invention comprises from 25 to 300 moles of butylene oxide units, preferably from 50 to 200 moles.

Preferably, the PAG of the invention comprises a ratio O / C (oxygen atom / carbon atom) in weight between 0.29 and 0.38, preferably between 0.29 and 0.35.

Preferably, the PAG of the invention has a molar mass between 5000 and 200 000 g / mol.

Preferably, the PAG of the invention has a kinematic viscosity measured at 100 ° C according to ASTM D445 (2015), between 50 and 500 mm 2 / s, a kinematic viscosity, measured at 40 ° C according to standard ASTM D445 (2015), between 500 and 4000 mm 2 / s and a viscosity index, measured according to ASTM D2270 (2012), between 160 and 300.

Preferably, the PAG of the invention, especially comprising 100% by weight of butylene oxide units, has a kinematic viscosity, measured at 40 ° C according to ASTM D445 (2015), between 1000 and 4500 mm 2 / s, preferably between 1000 and 4250 mm 2 / s, and preferably between 1100 and 4250 mm 2 / s.

Preferably, the PAG of the invention, especially comprising 100% by weight of butylene oxide units, has a viscosity index, measured according to ASTM D2270 (2012), between 180 and 300, preferably between 200 and 300 .

According to a particularly preferred embodiment, the PAG has a kinematic viscosity measured at 100 ° C according to ASTM D445 (2015) between 50 and 500 mm 2 / s, a kinematic viscosity measured at 40 ° C according to ASTM D445 (2015 ) of between 1000 and 4500 mm 2 / s and a viscosity index measured according to ASTM D2270 (2012) of between 180 and 300.

Preferably, the lubricant composition of the invention comprises at most 30% by weight of PAG, preferably from 2% to 30% by weight of PAG, more preferably from 2% to 15% relative to the total weight of the lubricating composition.

Preferably, the lubricant composition of the invention comprises at most 30% by weight of PAG, preferably from 6% to 30% by weight of PAG, more preferably from 9% to 16% relative to the total weight of the lubricating composition.

The lubricating composition used according to the invention comprises at least one base oil. Generally, the lubricating composition used according to the invention may comprise any type of lubricating base oil of mineral, synthetic or natural, animal or plant, known to those skilled in the art.

The base oils used in the lubricating compositions of the invention may be of mineral or synthetic origin oils 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.

Table A

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

Oils bases lubricating compositions used according to the invention may also be chosen from synthetic oils such certain carboxylic acid esters and alcohols, and among polyalphaolefins (PAO). 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 according to ASTM D445 (2015). The average molecular mass is generally between 250 and 3000 according to ASTM D5296.

Preferably, the base oils of the present invention are selected from the base oils above whose aromatic content is between 0 and 45%, preferably between 0 and 30%. The aromatic content of the oils was measured according to the UV Burdett method.

Advantageously, the lubricant composition used according to the invention comprises at least 50% by weight of base oils relative to the total weight of the composition.

More advantageously, the lubricant composition used according to the invention comprises at least 60 mass%, or even at least 70 wt%, base oil based on the total weight of the composition.

Of more advantageously, the lubricant composition used according to the invention comprises from 60 to 99.5% by weight of base oil, preferably from 70 to 99.5% by weight base oil, based on the total weight of the composition, preferably from 70 to 98%.

Numerous additives can be used for the lubricant composition used according to the invention.

Preferred additives for the lubricant composition used according to the invention are selected from the friction modifiers, detergents, antiwear additives, extreme pressure additives, viscosity improvers index, dispersants, antioxidants, improvers pour point, antifoams, thickeners and mixtures thereof.

Preferably, the lubricating composition used according to the invention comprises at least one antiwear additive, at least one extreme pressure additive or mixtures thereof. Anti-wear additives and extreme pressure additives protect formation by rubbing surfaces of a protective film adsorbed on these surfaces. There are a wide variety of anti-wear additives. Preferably the lubricating composition according to the invention, the anti-wear additives are 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 2 ) (OR 3 )) 2 , wherein R2 and R 3 , identical or different, independently represent an alkyl, preferably an alkyl group having 1 to 18 carbon atoms. Phosphates amines are also anti-wear additives that can be used in the composition

lubricating the invention. However, phosphorus brought by these additives can act as a poison for automobile catalytic systems because these additives are generators of ashes. Can minimize these effects by partially substituting the amine phosphates by additives bringing no phosphorus, such as, for example, polysulfides, such as sulfurized olefins. 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 lubricating composition, antiwear and extreme pressure additives additives.

Advantageously, the lubricating composition according to the invention may comprise at least one friction modifier additive. The friction modifier additive can be selected from a compound supplying metal elements and a free compound of ashes. Among the compounds providing the metallic elements include transition metal complexes such as Mo, Sb, Sn, Fe, Cu, Zn whose ligands can be hydrocarbon compounds containing oxygen, nitrogen, sulfur or phosphorus. The ashless friction modifier additives are usually of organic origin and may 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 from 0.01 to 2% by weight or 0.01 to 5% by weight, preferably from 0.1 to 1, 5% by mass or 0.1 to 2% by weight based on the total weight of the lubricating composition, friction modifier additive.

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.

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 in C 1 -C 12 , the Ν , Ν'-dialkyl-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 CC 10 , preferably an alkyl group -C 6 , preferably an alkyl group C4 , 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 4 R 5 R 6 wherein R 4 represents an aliphatic group or an aromatic group, optionally substituted, R 5 represents an aromatic group optionally substituted, R 6 represents a hydrogen atom, an alkyl group, an aryl group or a group of formula R 7 S (0) z R8 in which R 7 represents an alkylene group or alkenylene group, R 8represents an alkyl group, an alkenyl group or an aryl group and z represents 0, 1 or 2. sulfurized alkyl phenols or their alkali and alkaline earth metal salts 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. Advantageously, the lubricant composition comprises at least one antioxidant ashless additive. 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 lubricating composition according to the invention are generally known to those skilled in the art. The detergent additives can be anionic compounds comprising a long

lipophilic hydrocarbon chain and a hydrophilic head. The associated cation 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 lubricating composition according to the invention may comprise from 0.5 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.

The lubricating composition of the present invention may also comprise at least one additive improving the viscosity index. Examples of additives which improve the viscosity index, there may be mentioned ester polymers, homopolymers or copolymers, hydrogenated or non-hydrogenated, styrene, butadiene and isoprene, polyacrylates, polymethacrylates (PMA) olefins or copolymers, including ethylene / propylene copolymers.

The lubricating composition according to the invention may be in various forms. The lubricating composition according to the invention may in particular be an anhydrous composition. Preferably, the lubricant composition is not an emulsion.

Preferably, the base oil of the composition according to the invention is selected from Group II oils and oils of group III as defined above.

Preferably, the base oil of the composition according to the invention comprises at least a polyalphaolefin (PAO) as described above, in particular an alkene oligomer whose final viscosity is between 2 and 500 cSt.

Preferably, the base oil of the composition according to the invention is selected from Group II oils and oils of group III as defined above and at least one polyalphaolefin (PAO) as described above.

Advantageously, the lubricating composition according to the invention has excellent shear stability. Shear stability can especially be determined from the kinematic viscosities before and after a shearing process according to the KRL test 20h according to CEC-L-45-A-99 (2014). Advantageously, the shear loss is less than 5%.

Da Advantageously, the lubricating composition according to the invention has low traction coefficients. The traction coefficient is determined by machine MTM (Mini Traction Machine) sold by PCS instrument. Watched the operating conditions are a temperature of 40 ° C under a load of 75N and a disc speed of 1 m / s for a SRR (slide report / rolling or sliding-rolling ratio in English) of 20%.

Advantageously, the lubricant composition of the invention has a stable viscosity to temperature.

Advantageously, the lubricant composition of the invention enables a gain in Fuel Eco.

Advantageously, the lubricant composition of the invention retains satisfactory anti-wear properties.

Advantageously, the lubricating composition according to the invention allows a performance gain on the cold properties.

The lubricant composition of the invention is particularly useful for the lubrication of motor vehicle transmission components, including transmission for light or heavy vehicle, for example gearboxes, bridges,

Any manual gearbox and heavyweight bridges; or gears, including industrial gears. Thus, the present invention relates to the use of a lubricating composition according to the invention for lubricating the motor vehicle transmission components, including transmission for light or heavy vehicle, for example gearboxes, bridges, preferably gearbox manual and heavy bridges; or gears, including industrial gears. Preferably, in the context of lubricants for transmissions of any type 70W and 75W grade suitable.

The present invention also relates to a method of lubricating at least one mechanical part of a motor vehicle transmission member, in particular for transmission light or heavy vehicle, for example gearboxes, bridges, preferably manual gearbox and bridges heavyweight ; or gears, particularly industrial gears, said method comprising at least a step wherein said mechanical part is contacted with at least one lubricating composition according to the invention.

The lubricating composition according to the present invention can also be used for engine lubrication, in particular motor vehicle engine, preferably for SAE grades OW-8, 0W-12 and 0W-16.

The invention also relates to the use of the lubricating composition according to the invention for reducing the traction coefficient of a vehicle engine oil.

The invention also relates to the use of the lubricating composition according to the invention to reduce the fuel consumption of a vehicle equipped with a bridge or a gearbox lubricated by means of this composition.

The invention also relates to the use of the lubricating composition according to the invention to reduce the fuel consumption of a vehicle equipped with a transmission lubricated by means of this composition.

The invention also relates to the use of the lubricating composition according to the invention for reducing the traction coefficient of a transmission oil, in particular a gear oil or axle oil.

The present application also relates to the use of at least one PAG as defined above in a lubricating composition, in particular for motor vehicles or gear transmissions bodies, including industrial gears, to increase the viscosity index of the composition lubricating while providing stability of the lubricant composition to shear.

CLAIMS

A lubricating composition comprising:

- at least a base oil;

- at least one polyalkylene glycol (PAG) comprising at least 50% by mass of oxide units of butylene and having a kinematic viscosity measured at 100 ° C according to ASTM D445 (2015) greater than or equal to 50 mm 2 / s, kinematic viscosity measured at 40 ° C according to ASTM D445 (2015) greater than or equal to 1000 mm 2 / s and a viscosity index measured according to ASTM D2270 (2012) greater than or equal to 180.

2. - A lubricating composition according to claim 1, wherein the PAG comprises from 25 to 300 moles of butylene oxide units, preferably from 50 to 200.

3. - A lubricant composition according to any one of claims 1 or 2, wherein the PAG comprises a O / C ratio (oxygen atom / carbon atom) by weight / mole of between 0.29 and 0.38 , preferably between 0.29 and 0.35.

4. A lubricating composition according to any one of claims 1 to 3, wherein the PAG comprises at least 80% by mass of oxide units butylene.

5. - A lubricant composition according to any one of claims 1 to 4, wherein the alkylene oxide units of the PAG are only oxide units butylene.

6. - A lubricant composition according to any one of claims 1 to 5, wherein the PAG has a kinematic viscosity measured at 100 ° C according to ASTM D445 (2015) between 50 and 500 mm 2 / s, a kinematic viscosity measured at 40 ° C according to ASTM D445 (2015) of between 1000 and 4500 mm 2 / s and a viscosity index measured according to ASTM D2270 (2012) of between 180 and 300.

7. - A lubricant composition according to any one of claims 1 to 6 comprising at most 30% by weight of PAG, preferably from 6% to 30%, more preferably from 9% to 16%.

8. A lubricating composition according to any one of claims 1 to 7, wherein the PAG is obtained by reacting one or more polyols containing 2 to 12 carbon atoms, preferably diol, with butylene oxides.

9. A lubricating composition according to any one of claims 1 to 8, wherein the base oil is selected from Group II oils and Group III oils.

10. - Use of a lubricating composition according to any one of claims 1 to 9, for the lubrication of motor vehicle transmission components, including transmission for light and heavy vehicles, for example gearboxes, bridges, preferably manual gearbox and heavy bridges; or for industrial gears.

January 1. - Use of a lubricating composition according to any one of claims 1 to 9 for the engine lubrication, in particular motor vehicle engine, preferably for SAE grades OW-8, OW-12 and OW-16.

12. - A method of lubricating at least one mechanical part of a motor vehicle transmission member or industrial gears, said method comprising at least a step wherein said mechanical part is contacted with at least one lubricating composition according to any one of claims 1 to 9.