Use of a monoester in a lubricant composition for vehicle transmissions

Abstract

The present invention relates to the use of a composition comprising 1-methylheptyl laurate as a lubricant composition for transmissions.

Description

[0001] Use of a monoester in a lubricating composition for vehicle transmissions

[0002] Technical field

[0003] The present invention relates to the field of lubricating compositions, more particularly the field of lubricating compositions for transmissions in vehicles with thermal engines (gearboxes and / or axles) as well as transmissions, in particular the reducer, in the propulsion systems of electric or hybrid vehicles. It relates more particularly to the use of a monoester in order to improve the efficiency performance of transmissions in thermal engines as well as the efficiency performance for the reducers of electric motors.

[0004] Prior art

[0005] Lubricating compositions, also called "lubricants", are commonly used in the various components of motor vehicles for the main purpose of reducing friction forces between the various moving metal parts in these components, in particular the engine, the transmission and the hydraulic circuit. They are also effective in preventing premature wear or even damage to these parts, and in particular to their surface. To do this, a lubricating composition is conventionally composed of a base oil to which are generally associated several additives dedicated to boosting the lubricating performance of the base oil, such as for example friction modifying additives, but also to provide additional performance.

[0006] Lubricating compositions for transmissions (e.g. gearboxes or axles) must meet numerous requirements, particularly with regard to the strict specifications imposed by car manufacturers. In particular, they must have satisfactory properties in terms of viscosity, viscosity-temperature resistance, cold performance, etc. suitable for their use in a transmission component, particularly in the gearbox or axles, in a vehicle.

[0007] The evolution of international standards for reducing CO2 emissions, but also for reducing energy consumption, is pushing car manufacturers to offer alternatives to combustion engines. One of the solutions identified by car manufacturers is to replace combustion engines with electric motors. Research into reducing CO2 emissions has therefore led to the development of electric vehicles by several car companies.

[0008] For the purposes of the present invention, the term “electric vehicle” means a vehicle comprising an electric motor as the sole means of propulsion, whereas a hybrid vehicle comprises a combustion engine and an electric motor as combined means of propulsion.

[0009] For the purposes of the present invention, the term "propulsion system" is understood to mean a system comprising the mechanical parts necessary for the propulsion of an electric vehicle. The propulsion system thus more particularly encompasses an electric motor comprising the rotor-stator assembly of the power electronics (dedicated to speed regulation), a transmission (also called a reducer, and when the reducer is attached to the motor, it is then referred to as a geared motor) and a battery. The battery itself is generally made up of a set of electrical accumulators, called cells.

[0010] There is a need to provide lubricant compositions of renewable plant origin with low environmental impact.

[0011] Furthermore, current environmental concerns, particularly with a view to reducing carbon dioxide emissions, are leading to an urgent need to reduce the fuel consumption of motor vehicles. As such, it is known that lubricating compositions represent an effective means of acting on fuel consumption via their impact on the friction forces generated between the various components of motor vehicles. Thus, there is a need to develop lubricants that can reduce friction in gearboxes and axle differentials.

[0012] Improving the “Fuel Eco” properties of transmission lubricants, while maintaining the required high levels of performance, remains a challenge.

[0013] The invention specifically aims to propose a monoester that can be entirely biosourced and is capable of improving the efficiency performance of transmissions in thermal engines as well as the efficiency performance for reducers in electric motors. Summary of the invention

[0014] The present invention thus relates to the use of a composition comprising 1-methylheptyl laurate, as a lubricating composition for transmissions.

[0015] According to one embodiment, the lubricating composition comprising 1-methylheptyl laurate is used for transmissions in thermal engines and / or for reducers in electric motors.

[0016] According to one embodiment, the lubricating composition comprising 1-methylheptyl laurate is used to improve the performance of transmissions.

[0017] According to one embodiment, the lubricating composition comprising 1-methylheptyl laurate is used to reduce the fuel consumption of a vehicle equipped with a transmission member, in particular a gearbox and / or an axle, lubricated by means of said lubricating composition.

[0018] According to one embodiment, the lubricating composition comprising 1-methylheptyl laurate is used to improve the efficiency of reducers in electric motors.

[0019] According to one embodiment, the lubricating composition comprising 1-methylheptyl laurate is used to extend the battery life of an electric or hybrid vehicle.

[0020] Preferably, the lubricating composition comprises 5 to 50% by mass of 1-methylheptyl laurate, preferably 10 to 40% by mass of 1-methylheptyl laurate, relative to the total mass of the lubricating composition.

[0021] Preferably, the lubricating composition comprises: from 5 to 50% by mass, preferably from 10 to 40% by mass, of 1-methylheptyl laurate, and from 50 to 95% by mass, preferably from 60 to 90% by mass, of one or more base oils other than 1-methylheptyl laurate, relative to the total mass of the lubricating composition.

[0022] Preferably, the lubricating composition has a kinematic viscosity at 100°C ranging from 1 to 6 mm 2 / s, preferably ranging from 1 to 4 mm 2 / s.

[0023] Preferably, the 1-methylheptyl laurate has a carbon content of biological origin of at least 90% by weight relative to the total weight of carbon atoms. According to one embodiment, the lubricating composition comprises, in addition to the 1-methylheptyl laurate, at least one additive chosen from antioxidants, viscosity index improving additives, pour point depressant additives, antifoaming agents, anticorrosion agents, antiwear and / or extreme pressure additives, friction modifiers, detergents, dispersing agents and mixtures thereof, in particular from antioxidants, pour point depressant additives, antifoaming agents and anticorrosion agents.

[0024] Preferably, the additive(s) represent from 0.01 to 20% by mass, preferably from 0.1 to 15% by mass, more preferably from 0.5 to 10% by mass, relative to the total mass of the lubricating composition.

[0025] The invention aims specifically to improve the efficiency performance of transmissions in thermal engines as well as the efficiency performance for reducers in electric motors.

[0026] The present invention thus aims to improve the “fuel eco” properties for thermal engines and to extend the battery life for electric motors.

[0027] Other characteristics, variants and advantages of the implementation of a monoester according to the invention will emerge more clearly on reading the description and examples which follow, given by way of illustration and not limitation of the invention.

[0028] In the rest of the text, the expressions "between ... and ...", "ranging from ... to . . ." and "varying from ... to ..." are equivalent and are intended to mean that the limits are included, unless otherwise stated.

[0029] Unless otherwise indicated, the expression “comprising a” should be understood as “comprising at least one”.

[0030] Brief description of the drawings

[0031] [Fig 1] schematically represents an electric or hybrid vehicle propulsion system. Detailed description

[0032] Firstly, the invention relates to the use of 1-methylheptyl laurate in a lubricating composition for transmissions.

[0033] The invention relates to the use of a composition comprising 1-methylheptyl laurate as a lubricating composition for transmissions.

[0034] 1-Methylheptyl laurate can be obtained by esterification reaction between lauric acid and octan-2-ol.

[0035] Preferably, the lauric acid and / or octan-2-ol are of bio-sourced origin. The bio-sourced octan-2-ol can be obtained by cracking ricinoleic acid.

[0036] Thus, preferably, 1-methylheptyl laurate has a carbon content of biological origin of at least 90% by weight, preferably at least 95% by weight, advantageously 100% by weight, relative to the total weight of carbon atoms.

[0037] For the purposes of the present invention, the bio-based carbon content may be measured according to ASTM D6866.

[0038] 1-Methylheptyl laurate, also called monoester of the invention, is used in a lubricating composition for transmissions.

[0039] Annex base oil(s)

[0040] The lubricating composition used according to the invention may comprise, in addition to the monoester according to the invention, one or more base oils distinct from the monoester according to the invention.

[0041] Said base oil(s), optionally present in a lubricating composition according to the invention, are chosen appropriately, with regard to their compatibility with the monoester used according to the invention.

[0042] It can be a mixture of several base oils, for example a mixture of two, three or four base oils.

[0043] Preferably, the base oil or mixture of additional base oils, used in a lubricating composition according to the invention, may have a kinematic viscosity, measured at 100°C according to standard ASTM D445, ranging from 1.5 to 8 mm 2 / s, especially from 1.5 to 6.1 mm 2 / s, more particularly from 1.5 to 4.1 mm 2 / s, even more particularly from 1.5 to 2.1 mm 2 / s. Base oils can be chosen from oils of mineral or synthetic origin belonging to groups I to V according to the classes defined in the API classification (or their equivalents according to the ATIEL classification) and presented in table 1 below or their mixtures.

[0044] [Table 1]

[0045] Mineral base oils include all types of base oils obtained by atmospheric and vacuum distillation of crude oil, followed by refining operations such as solvent extraction, de-alphatting, solvent dewaxing, hydrotreating, hydrocracking, hydroisomerization and hydrofinishing.

[0046] Blends of synthetic and mineral oils, which can be bio-sourced, can also be used.

[0047] There are generally no limitations on the use of additional different base oils to make lubricating compositions, except that they should preferably have properties, in particular viscosity index, sulfur content or oxidation resistance, suitable for use in propulsion systems of an electric or hybrid vehicle.

[0048] The base oils may also be chosen from synthetic oils, such as certain esters of carboxylic acids and alcohols, other than the diester defined according to the invention, from polyalphaolefins (PAOs), and from polyalkylene glycols (PAGs) obtained by polymerization or copolymerization of alkylene oxides comprising from 2 to 8 carbon atoms, in particular from 2 to 4 carbon atoms. The PAOs used as base oils are, for example, obtained from monomers comprising from 4 to 32 carbon atoms, for example from octene or decene.

[0049] The mass average molecular mass of PAO can vary quite widely. Preferably, the mass average molecular mass of PAO is less than 600 Da. The mass average molecular mass of PAO can also range from 100 to 600 Da, from 150 to 600 Da, or from 200 to 600 Da.

[0050] For example, the PAOs used in the context of the invention, having a kinematic viscosity, measured at 100°C according to the ASTM D445 standard, ranging from 1.5 to 8 mm 2 / s are sold commercially by Ineos under the brands Durasyn® 162, Durasyn® 164, Durasyn® 166 and Durasyn® 168.

[0051] Advantageously, the additional base oil or oils are chosen from polyalphaolefins (PAOs).

[0052] It is up to a person skilled in the art to adjust the content of additional base oil(s) present in a lubricating composition according to the invention.

[0053] According to one embodiment, a composition used according to the invention may comprise from 5 to 95% by mass, preferably from 50 to 95% by mass, more preferably from 60 to 90% by mass, of one or more base oils different from the monoester according to the invention, relative to the total mass of said composition.

[0054] Additives

[0055] A lubricating composition according to the invention may further comprise one or more additives known to those skilled in the art in the field of transmission lubrication, in particular for thermal engines and for propulsion systems of electric or hybrid vehicles.

[0056] The additives that can be incorporated into a composition according to the invention can be chosen from antioxidants, pour point depressant additives, antifoam agents, anticorrosion agents, antiwear and / or extreme pressure additives, friction modifiers, detergents, dispersing agents and mixtures thereof, in particular from antioxidants, pour point depressant additives, antifoam agents and anticorrosion agents. Preferably, a lubricating composition according to the invention can further comprise one or more additives chosen from antioxidants, antifoams, pour point improvers, viscosity index improvers and anticorrosion agents.

[0057] The addition of one or more additives chosen from anti-wear additives, friction modifiers, detergents, extreme pressure additives and dispersants, may also prove advantageous in the context of the implementation of the lurifying composition according to the invention as a multifunctional fluid, for example for cooling the battery and / or the power electronics, and for lubricating parts of the propulsion system, for example the transmission, in an electric or hybrid vehicle.

[0058] It is understood that the nature and quantity of additives used are chosen so as not to affect the properties of the lubricating composition conferred by the monoester according to the invention.

[0059] These additives can be introduced in isolation and / or in the form of a mixture similar to those already available for sale for commercial lubricant formulations for vehicle engines, with performance levels as defined by the ACEA (Association of European Automobile Manufacturers) and / or the API (American Petroleum Institute), well known to those skilled in the art.

[0060] Said additive(s) may be present in the lubricating composition according to the invention in a content of less than or equal to 20% by mass, in particular ranging from 0.01 to 20% by mass, preferably from 0.1 to 15% by mass, more preferably from 0.5 to 10% by mass, relative to the total mass of said composition.

[0061] A lubricating composition used according to the invention can thus comprise at least one antioxidant additive.

[0062] The invention thus relates, according to another of its aspects, to a lubricating composition, in particular capable of lubricating a transmission, in particular of a thermal engine or of a propulsion system of an electric or hybrid vehicle, said composition comprising (i) at least one monoester according to the invention, and (ii) at least one antioxidant additive. The antioxidant additive generally makes it possible to delay the degradation of the composition in service. This degradation can in particular result in the formation of deposits, by the presence of sludge or by an increase in the viscosity of the composition.

[0063] Antioxidant additives act in particular as radical inhibitors or hydroperoxide destroyers. Among the commonly used antioxidant additives, mention may be made of phenolic antioxidant additives, amine antioxidant additives, and phosphosulfur antioxidant additives. Some of these antioxidant additives, for example phosphosulfur antioxidant additives, may be ash-generating. Phenolic antioxidant additives may be ash-free or in the form of neutral or basic metal salts. The antioxidant additives may in particular be chosen from sterically hindered phenols, sterically hindered phenol esters and sterically hindered phenols comprising a thioether bridge, diphenylamines, diphenylamines substituted by at least one C1-C12 alkyl group, N,N'-dialkylaryldiamines and mixtures thereof.

[0064] Preferably according to the invention, the sterically hindered phenols are chosen from compounds comprising a phenol group of which at least one vicinal carbon of the carbon carrying the alcohol function is substituted by at least one C1-C10 alkyl group, preferably a C1-C6 alkyl group, preferably a C4 alkyl group, preferably by the tert-butyl group.

[0065] Amino compounds are another class of antioxidant additives that can be used, possibly in combination with phenolic antioxidant additives. Examples of amino compounds are aromatic amines, for example aromatic amines of the formula NR 4 R 5 R 6 in which R 4 represents an aliphatic group or an aromatic group, optionally substituted, R 5 represents an aromatic group, optionally substituted, R 6represents a hydrogen atom, an alkyl group, an aryl group or a group of formula R 7 S(O) Z R 8 in which R 7 represents an alkylene group or an alkenylene group, R 8 represents an alkyl group, an alkenyl group or an aryl group and z represents 0, 1 or 2.

[0066] 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, e.g., copper thio- or dithio-phosphates, copper carboxylic acid salts, dithiocarbamates, sulphonates, phenates, copper acetylacetonates. Copper I and II salts, succinic acid or anhydride salts can also be used.

[0067] Advantageously, a lubricating composition comprises at least one ash-free antioxidant additive.

[0068] Said additive(s) may be used, in a lubricating composition according to the invention, at a rate of 0.1 to 2% by mass, relative to the total mass of the composition.

[0069] A lubricating composition according to the invention may comprise at least one anti-wear and / or extreme pressure additive.

[0070] Anti-wear additives and extreme pressure additives protect friction surfaces by forming a protective film adsorbed on these surfaces.

[0071] There are a wide variety of anti-wear additives. Preferably, the anti-wear additives are chosen from phosphosulfur additives such as metal alkylthiophosphates, in particular zinc alkylthiophosphates, and more specifically zinc dialkyldithiophosphates or ZnDTP. The preferred compounds are of formula Zn((SP(S)(OQ 2 )(OQ 3 ))2, in which Q 2 and Q 3 , identical or different, independently represent an alkyl group, preferably an alkyl group comprising from 1 to 18 carbon atoms.

[0072] Amine phosphates are also anti-wear additives that can be used in a composition according to the invention. However, the phosphorus provided by these additives can act as a poison for automobile catalytic systems because these additives generate ash. These effects can be minimized by partially substituting the amine phosphates with additives that do not provide phosphorus, such as, for example, polysulfides, in particular sulfur-containing olefins.

[0073] A lubricating composition may comprise from 0.01 to 6% by mass, preferably from 0.05 to 4% by mass, more preferably from 0.1 to 2% by mass of anti-wear additives and extreme pressure additives, by mass relative to the total mass of composition. A lubricating composition according to the invention may further comprise an antifoaming agent.

[0074] The antifoam agent can be chosen from silicones.

[0075] A lubricating composition may comprise from 0.01 to 2% by mass or from 0.01 to 5% by mass, preferably from 0.1 to 1.5% by mass or from 0.1 to 2% by mass of antifoaming agent, relative to the total mass of the composition.

[0076] A lubricating composition according to the invention may comprise at least one friction modifying additive.

[0077] The friction modifying additive may be chosen from a compound providing metallic elements and an ash-free compound. Among the compounds providing metallic elements, mention may be made of transition metal complexes such as Mo, Sb, Sn, Fe, Cu, Zn, the ligands of which may be hydrocarbon compounds comprising oxygen, nitrogen, sulfur or phosphorus atoms. The ash-free friction modifying additives are generally of organic origin and may be chosen from monoesters of fatty acids and polyols, alkoxylated amines, alkoxylated fatty amines, fatty epoxides, borate fatty epoxides; fatty amines or fatty acid glycerol esters. According to the invention, the fatty compounds comprise at least one hydrocarbon group comprising from 10 to 24 carbon atoms.

[0078] A lubricating composition may comprise from 0.01 to 2% by mass or from 0.01 to 5% by mass, preferably from 0.1 to 1.5% by mass or from 0.1 to 2% by mass of friction modifying additive, relative to the total mass of the composition.

[0079] A lubricating composition according to the invention may comprise at least one additive making it possible to improve the viscosity index of the lubricating composition (in English “viscosity index improver”).

[0080] For the purposes of the invention, the term "additive for improving the viscosity index" means a chemical compound that ensures good cold resistance and minimal viscosity at high temperature of the lubricating composition.

[0081] Examples of viscosity index improving polymers include polymeric esters; hydrogenated or non-hydrogenated homopolymers or copolymers of styrene, butadiene and isoprene; homopolymers or copolymers of olefins, such as ethylene or propylene; polyacrylates and polymethacrylates (PMA).

[0082] The lubricating composition according to the invention typically comprises from 0.1% to 15% by mass of additive(s) improving the viscosity index, relative to the total mass of the lubricating composition.

[0083] A lubricating composition according to the invention may comprise at least one detergent additive.

[0084] Detergent additives generally reduce the formation of deposits on the surface of metal parts by dissolving secondary oxidation and combustion products.

[0085] Detergent additives usable in a lubricating composition are generally known to those skilled in the art. The detergent additives may be anionic compounds comprising a lipophilic hydrocarbon group and a hydrophilic head. The associated cation may be a metal cation of an alkali or alkaline earth metal.

[0086] The detergent additives are preferably chosen from alkali metal or alkaline earth metal salts of carboxylic acids, sulfonates, salicylates, naphthenates, as well as phenate salts. The alkali and alkaline earth metals are preferably calcium, magnesium, sodium or barium.

[0087] These metal salts generally comprise the metal in a stoichiometric quantity or in excess, i.e. in a quantity greater than the stoichiometric quantity. These are then overbased detergent additives; the excess metal providing the overbased character to the detergent additive is then generally in the form of an oil-insoluble metal salt, for example a carbonate, a hydroxide, an oxalate, an acetate, a glutamate, preferably a carbonate.

[0088] A lubricating composition used according to the invention may, for example, comprise from 2 to 4% by mass of detergent additive, relative to the total mass of the composition.

[0089] A lubricating composition implemented 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 composition. Examples of pour point depressant additives include polyalkyl methacrylates, polyacrylates, polyarylamides, polyalkylphenols, polyalkylnaphthalenes, and alkylated polystyrenes.

[0090] A lubricating composition used according to the invention may, for example, comprise from 0.05 to 2% by mass of pour point lowering additive, relative to the total mass of the composition.

[0091] Also, a lubricating composition implemented according to the invention may comprise at least one dispersing agent.

[0092] The dispersing agent may be chosen from Mannich bases, succinimides and their derivatives. A lubricating composition used according to the invention may, for example, comprise from 0.2 to 10% by mass of dispersing agent, relative to the total mass of the composition.

[0093] According to a particular embodiment, a lubricating composition used according to the invention comprises, or is formed from (i) the monoester according to the invention and (ii) at least one additive chosen from antioxidants, antifoaming agents, pour point depressant additives, anticorrosion agents, antiwear and / or extreme pressure additives, friction modifiers, detergents, dispersing agents and mixtures thereof, preferably from antioxidants, pour point depressant additives, antifoaming agents, anticorrosion agents, and mixtures thereof.

[0094] Advantageously, a lubricating composition used according to the invention comprises (i) the monoester according to the invention and (ii) at least one antioxidant additive.

[0095] According to a particular embodiment, a lubricating composition implemented according to the invention comprises, or even consists of:

[0096] - from 5 to 50% by mass, preferably from 10 to 40% by mass, of 1-methylheptyl laurate; - from 50 to 95% by mass, preferably from 60 to 90% by mass, of one or more base oils other than 1-methylheptyl laurate;

[0097] - optionally from 0.01 to 20% by mass, preferably from 0.1 to 15% by mass, more preferably from 0.5 to 10% by mass, of one or more additives chosen from friction modifying additives, anti-wear additives, extreme pressure additives, detergents, antioxidants, viscosity index (VI) improvers, pour point depressant (PPD) additives, dispersants, anti-foaming agents, thickeners, corrosion inhibitors, copper passivating agents, and mixtures thereof; and the contents being expressed relative to the total mass of said composition.

[0098] According to a particular embodiment, a lubricating composition implemented according to the invention comprises, or even consists of:

[0099] - from 5 to 45% by mass, preferably from 10 to 40% by mass, of 1-methylheptyl laurate;

[0100] - from 50 to 95% by mass, preferably from 55 to 90% by mass, of one or more base oils other than 1-methylheptyl laurate;

[0101] - from 0.01 to 20% by mass, preferably from 0.1 to 15% by mass, more preferably from 0.5 to 10% by mass, of one or more additives chosen from friction modifying additives, anti-wear additives, extreme pressure additives, detergents, antioxidants, viscosity index (VI) improvers, pour point depressant (PPD) additives, dispersants, anti-foaming agents, thickeners, corrosion inhibitors, copper passivating agents, and mixtures thereof; and the contents being expressed relative to the total mass of said composition.

[0102] According to a particular embodiment, a lubricating composition implemented according to the invention comprises, or even consists of:

[0103] - from 5 to 50% by mass, preferably from 10 to 40% by mass, of 1-methylheptyl laurate;

[0104] - from 50 to 95% by mass, preferably from 55 to 90% by mass, of one or more base oils other than esters; - optionally from 0.01 to 20% by mass, preferably from 0.1 to 15% by mass, more preferably from 0.5 to 10% by mass, of one or more additives chosen from friction modifying additives, anti-wear additives, extreme pressure additives, detergents, antioxidants, viscosity index (VI) improvers, pour point depressant (PPD) additives, dispersants, anti-foaming agents, thickeners, corrosion inhibitors, copper passivating agents, and mixtures thereof; and the contents being expressed relative to the total mass of said composition.

[0105] According to a particular embodiment, a lubricating composition implemented according to the invention comprises, or even consists of:

[0106] - from 5 to 45% by mass, preferably from 10 to 40% by mass, of 1-methylheptyl laurate;

[0107] - from 50 to 95% by mass, preferably from 55 to 90% by mass, of one or more base oils other than the esters;

[0108] - from 0.01 to 20% by mass, preferably from 0.1 to 15% by mass, more preferably from 0.5 to 10% by mass, of one or more additives chosen from friction modifying additives, anti-wear additives, extreme pressure additives, detergents, antioxidants, viscosity index (VI) improvers, pour point depressant (PPD) additives, dispersants, anti-foaming agents, thickeners, corrosion inhibitors, copper passivating agents, and mixtures thereof; and the contents being expressed relative to the total mass of said composition.

[0109] According to a particular embodiment, a lubricating composition implemented according to the invention comprises, or even consists of:

[0110] - from 5 to 45% by mass, preferably from 10 to 40% by mass, of 1-methylheptyl laurate;

[0111] - from 50 to 95% by mass, preferably from 55 to 90% by mass, of one or more base oils other than the esters;

[0112] - from 0.01 to 20% by mass, preferably from 0.1 to 15% by mass, more preferably from 0.5 to 10% by mass, of one or more additives chosen from antioxidants, pour point lowering additives, anti-foaming agents, anti-corrosion agents, and mixtures thereof; and the contents being expressed relative to the total mass of said composition.

[0113] According to a particular embodiment, a lubricating composition implemented according to the invention comprises, or even consists of:

[0114] - from 5 to 50% by mass, preferably from 10 to 40% by mass, of 1-methylheptyl laurate;

[0115] - from 50 to 95% by mass, preferably from 55 to 90% by mass, of one or more mineral or synthetic base oils chosen from group I oils, group II oils, group III oils and group IV oils, and mixtures thereof;

[0116] - optionally from 0.01 to 20% by mass, preferably from 0.1 to 15% by mass, more preferably from 0.5 to 10% by mass, of one or more additives chosen from friction modifying additives, anti-wear additives, extreme pressure additives, detergents, antioxidants, viscosity index (VI) improvers, pour point depressant (PPD) additives, dispersants, anti-foaming agents, thickeners, corrosion inhibitors, copper passivating agents, and mixtures thereof; and the contents being expressed relative to the total mass of said composition.

[0117] According to a particular embodiment, a lubricating composition implemented according to the invention comprises, or even consists of:

[0118] - from 5 to 45% by mass, preferably from 10 to 40% by mass, of 1-methylheptyl laurate;

[0119] - from 50 to 95% by mass, preferably from 55 to 90% by mass, of one or more mineral or synthetic base oils chosen from group I oils, group II oils, group III oils and group IV oils, and mixtures thereof;

[0120] - from 0.01 to 20% by mass, preferably from 0.1 to 15% by mass, more preferably from 0.5 to 10% by mass, of one or more additives chosen from friction modifying additives, anti-wear additives, extreme pressure additives, detergents, antioxidants, viscosity index (VI) improvers, pour point depressant (PPD) additives, dispersants, anti-foaming agents, thickeners, corrosion inhibitors, copper passivating agents, and mixtures thereof; and the contents being expressed relative to the total mass of said composition.

[0121] According to a particular embodiment, a lubricating composition implemented according to the invention comprises, or even consists of:

[0122] - from 5 to 45% by mass, preferably from 10 to 40% by mass, of 1-methylheptyl laurate;

[0123] - from 50 to 95% by mass, preferably from 55 to 90% by mass, of one or more mineral or synthetic base oils chosen from group I oils, group II oils, group III oils and group IV oils, and mixtures thereof;

[0124] - from 0.01 to 20% by mass, preferably from 0.1 to 15% by mass, more preferably from 0.5 to 10% by mass, of one or more additives chosen from antioxidants, pour point lowering additives, anti-foaming agents, anti-corrosion agents, and mixtures thereof; and the contents being expressed relative to the total mass of said composition.

[0125] A lubricating composition used according to the invention advantageously has a kinematic viscosity, measured at 100°C according to standard ASTM D445, ranging from 1 to 6 mm 2 / s, preferably 1 to 4 mm 2 / s.

[0126] A lubricating composition used according to the invention advantageously has a kinematic viscosity, measured at 40°C according to standard ASTM D445, ranging from 2 to 20 mm 2 / s, preferably 3 to 10 mm 2 / s.

[0127] Application

[0128] As indicated previously, the lubricating composition according to the invention can be used as a lubricating fluid for transmission.

[0129] In particular, the lubricating composition defined in the present invention makes it possible to improve the performance of transmissions.

[0130] 1-Methylheptyl laurate improves transmission performance when incorporated into a lubricating composition used to lubricate transmissions. 1-Methylheptyl laurate also improves the fuel-saving properties, known as "Fuel-Eco" properties, of the lubricating composition comprising said 1-methylheptyl laurate. Indeed, 1-methylheptyl laurate reduces the traction coefficient of the lubricating composition comprising said 1-methylheptyl laurate.

[0131] Transmissions can be transmissions for thermal vehicle engines and / or transmissions for electric or hybrid vehicle propulsion systems.

[0132] The transmission of a propulsion system of an electric or hybrid vehicle more specifically comprises a speed reducer. Thus, the monoester according to the invention makes it possible in particular to improve the efficiency of the reducers in the propulsion systems of electric or hybrid vehicles.

[0133] As shown schematically in Figure 1, the propulsion system of an electric or hybrid vehicle includes in particular the electric motor part (1), an electric battery (2) and a transmission, and in particular a speed reducer (3).

[0134] The electric motor typically comprises power electronics (11) connected to a stator (13) and a rotor (14). The stator comprises coils, in particular copper coils, which are alternately supplied with an electric current. This generates a rotating magnetic field. The rotor itself comprises coils, permanent magnets or other magnetic materials, and is rotated by the rotating magnetic field.

[0135] The power electronics (11), stator (13) and rotor (14) of a propulsion system (1) are parts whose structure is complex and generates a large amount of heat during engine operation.

[0136] A bearing (12) is generally integrated between the stator (13) and the rotor (14). A transmission, and in particular a speed reducer (3), makes it possible to reduce the rotation speed at the output of the electric motor and to adapt the speed transmitted to the wheels, allowing at the same time to control the speed of the vehicle.

[0137] Advantageously, a lubricating composition defined in the present invention can be used to improve the efficiency of transmissions, in particular for thermal vehicle engines and for the propulsion system of an electric or hybrid vehicle. In particular, a lubricating composition defined in the present invention can be used to improve the efficiency of the reducers of the propulsion system of an electric or hybrid vehicle.

[0138] The invention also relates, according to another of its aspects, to a method for lubricating at least one mechanical part of a transmission member of motor vehicles, in particular light or heavy vehicles, for example gearbox, axles, preferably manual gearbox and heavy goods vehicle axles, or even reducer of electric or hybrid vehicles, said method comprising at least one step in which said mechanical part is brought into contact with at least one lubricating composition according to the invention.

[0139] The invention also relates to the use of the monoester according to the invention, as defined above, for reducing the traction coefficient of a lubricating composition for transmission in a motor vehicle, in particular a gearbox lubricant and / or an axle lubricant, in particular heavy goods vehicle axles, or even reducers for electric or hybrid vehicles.

[0140] Also, as mentioned above, a lubricating composition according to the invention has excellent properties in terms of reducing fuel consumption (“Fuel Eco” properties).

[0141] Advantageously, a lubricating composition according to the invention thus has low traction coefficients.

[0142] A lubricating composition defined in the invention can also be used to cool the electric motor of an electric or hybrid vehicle, in particular to cool the power electronics and / or the rotor and / or the stator of the electric motor and / or the geared motor.

[0143] The invention will now be described by means of the following examples, given of course for illustrative purposes and not as a limitation of the invention. Example

[0144] The properties of the monoester of the invention (El), ester of lauric acid and 2-octanol, were compared with another monoester, ester of lauric acid and 2-ethylhexanol (E2).

[0145] 2-ethylhexanol is not of bio-sourced origin whereas the 2-octanol used in this example is of bio-sourced origin.

[0146] Kinematic viscosity was measured at 40°C (KV40) and 100°C (KV100) according to ASTM D445.

[0147] The mini pour point (MP) is measured according to ASTM D7346.

[0148] Viscosity index (VI) is measured according to ASTM D2270.

[0149] Tribological properties can be assessed using a PCS Instruments MTM (Mini Traction Machine, also known as a ball-and-plane) tribometer test. This test is used to assess lubricant performance in terms of friction in mixed / limit conditions depending on the load, pressure, or speed conditions applied.

[0150] The traction coefficient of the tested lubricating compositions is determined at 40°C and 100°C and 140°C by using a hardened steel ball of approximately 2 cm in diameter, for example 1.905 cm in diameter, on a hardened steel plane.

[0151] This device allows a steel ball and a steel plane to be put into relative motion in order to determine the friction coefficients for a given lubricant composition, while varying various properties such as speed, load, and temperature. The hardened steel plane is of AISI 52100 reference with a mirror finish and the ball is also of AISI 52100 reference made of hardened steel.

[0152] The applied load is 25 N respectively and the rotation speed varies from 20 mm / s to 2500 mm / s. (SRR (slide-roll-ratio =5%))

[0153] Approximately 50 ml of the tested lubricating composition was introduced into the device. The ball is engaged face against plane, said ball and said plane being actuated independently so as to create a mixed rolling / sliding contact.

[0154] The traction coefficient is measured and recorded using a force sensor.

[0155] Table 2 lists the results of tribological property measurements at 40°C (40°C SRR 5%), 100°C (100°C SRR 5%) and 140°C (140°C SRR 5%). [Table 2]

[0156] As the results in this table show, the monoester according to the invention has a better traction coefficient, i.e. a lower traction coefficient, than the comparative monoester of the state of the art. This lower traction coefficient will allow for a better gain in terms of fuel economy (Fuel-Eco) for a thermal engine and a better gain in terms of battery autonomy for an electric or hybrid vehicle.

Claims

Claims 1. Use of a composition comprising 1-methylheptyl laurate, as a lubricating composition for transmissions.

2. Use according to claim 1, for transmissions in thermal engines and / or for reducers in electric motors.

3. Use according to any one of claims 1 to 2, to improve the efficiency of transmissions.

4. Use according to any one of claims 1 to 3, for reducing the fuel consumption of a vehicle equipped with a transmission member, in particular a gearbox and / or an axle, lubricated by means of said lubricating composition.

5. Use according to any one of claims 1 to 3, for improving the efficiency of reducers in electric motors.

6. Use according to any one of claims 1 to 3 or 5, for extending the battery life of an electric or hybrid vehicle.

7. Use according to any one of claims 1 to 6, wherein the lubricating composition comprises 5 to 50% by mass of 1-methylheptyl laurate, preferably 10 to 40% by mass of 1-methylheptyl laurate, relative to the total mass of the lubricating composition.

8. Use according to any one of claims 1 to 7, in which the composition comprises: - from 5 to 50% by mass, preferably from 10 to 40% by mass, of 1-methylheptyl laurate, and - from 50 to 95% by mass, preferably from 60 to 90% by mass, of one or more base oils other than 1-methylheptyl laurate, relative to the total mass of the lubricating composition.

9. Use according to any one of claims 1 to 8, in which the lubricating composition has a kinematic viscosity at 100°C ranging from 1 to 6 mm 2 / s, preferably ranging from 1 to 4 mm 2 / s.

10. Use according to any one of claims 1 to 9, in which the 1-methylheptyl laurate has a carbon content of biological origin of at least 90% by weight relative to the total weight of carbon atoms.

11. Use according to any one of claims 1 to 10, characterized in that said lubricating composition comprises, in addition to 1-methylheptyl laurate, at least one additive chosen from antioxidants, viscosity index improving additives, pour point lowering additives, anti-foaming agents, anti-corrosion agents, anti-wear and / or extreme pressure additives, friction modifiers, detergents, dispersing agents and mixtures thereof, in particular from antioxidants, pour point lowering additives, anti-foaming agents and anti-corrosion agents.

12. Use according to claim 11, in which the additive(s) represent from 0.01 to 20% by mass, preferably from 0.1 to 15% by mass, more preferably from 0.5 to 10% by mass, relative to the total mass of the lubricating composition.

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