Use of monoesters in lubricating compositions for vehicle transmissions

Abstract

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

Description

Technical Field

[0001] The present invention relates to the field of lubricating compositions, more specifically to the field of lubricating compositions for transmissions (gearboxes and / or axles) in vehicles with internal combustion engines and transmissions (more specifically reduction gears) in propulsion systems of electric or hybrid vehicles. The present invention more specifically relates to the use of monoesters for improving the efficiency properties of transmissions in internal combustion engines and the efficiency properties of reduction gears of electric motors. Background Art

[0002] Lubricating compositions, also called "lubricants", are generally used in different parts of motor vehicles, with the main purpose of reducing the friction between the different metal parts moving in the parts, more particularly in the engine, the transmission and the hydraulic circuit. In addition, they are effective in preventing premature wear or even damage to these parts, in particular their surfaces. To this end, lubricating compositions generally consist of a base oil, which is usually combined with various additives dedicated to stimulating the lubricating properties of the base oil (for example friction modifier additives), and also to obtain additional properties.

[0003] Lubricating compositions for transmission devices, such as gearboxes or axles, must meet numerous requirements, in particular with regard to the stringent specifications imposed by automobile manufacturers. More particularly, they must have satisfactory properties in terms of viscosity, viscosity-temperature resistance, cold performance, etc., suitable for their implementation in transmission parts in vehicles, in particular in gearboxes or axles.

[0004] The evolution of international standards for reducing CO2 emissions as well as reducing energy consumption is driving car manufacturers to come up with alternative solutions to the internal combustion engine.

[0005] One of the solutions identified by car manufacturers is to replace the internal combustion engine with an electric motor. Therefore, research on reducing CO2 emissions has led many car companies to develop electric vehicles.

[0006] An "electric vehicle" as defined in the present invention refers to a vehicle including an electric motor as the sole propulsion means, while a hybrid vehicle includes an internal combustion engine and an electric motor as a combined propulsion means.

[0007] A "propulsion system" as defined in the present invention is a system comprising the mechanical components required to propel an electric vehicle. Thus, a propulsion system more specifically comprises an electric motor including a rotor-stator assembly of a power electronics system (dedicated to speed regulation), a transmission (also called a reduction gear, and when the reduction gear is connected to the engine, one speaks of an engine reduction gear) and a battery. Such a battery is usually composed of a group of accumulators called cells.

[0008] There is a need to provide lubricating compositions of renewable plant origin that have low environmental impact.

[0009] Furthermore, current environmental problems, especially those aimed at reducing carbon dioxide emissions, lead to an urgent need to reduce the fuel consumption of motor vehicles. Lubricating compositions are therefore known to represent an effective means of acting on fuel consumption through their influence on the friction forces generated between the different parts of a motor vehicle. It is therefore desirable to develop lubricants that reduce friction in gearboxes and axle differentials.

[0010] Improving the "fuel economy" performance of transmission lubricants while maintaining the required high level of performance remains a challenge.

[0011] It is an object of the present invention to specify a monoester which can be of completely biological origin and which is suitable for improving the efficiency properties of transmissions in internal combustion engines and of reduction gears in electric motors. Summary of the invention

[0012] The present invention therefore provides for the use of a composition comprising 1-methylheptyl laurate as a lubricating composition for a transmission.

[0013] According to one embodiment, the lubricating composition comprising 1-methylheptyl laurate is used for transmissions in thermal engines and / or for reduction gears in electric motors.

[0014] According to one embodiment, a lubricating composition comprising 1-methylheptyl laurate is used to improve the efficiency of a transmission.

[0015] According to one embodiment, a lubricating composition comprising 1-methylheptyl is used to reduce the fuel consumption of a vehicle equipped with transmission parts, in particular gearboxes and / or axles, which are lubricated by said lubricating composition.

[0016] According to one embodiment, a lubricating composition comprising 1-methylheptyl laurate is used to improve the efficiency performance of a reduction gear in an electric motor.

[0017] In one embodiment, a lubricating composition comprising 1-methylheptyl laurate is used to extend the autonomy of a battery of an electric or hybrid vehicle.

[0018] Preferably, the lubricating composition comprises 5 to 50 wt. % of 1-methylheptyl laurate, preferably 10 to 40 wt. % of 1-methylheptyl laurate, relative to the total weight of the lubricating composition.

[0019] Preferably, the lubricating composition comprises, relative to the total weight of the lubricating composition:

[0020] - 5 to 50% by weight, preferably 10 to 40% by weight, of 1-methylheptyl ester, and

[0021] 50% to 95% by weight, preferably 60% to 90% by weight, of one or more base oils other than 1-methylheptyl laurate.

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

[0023] Preferably, 1-methylheptyl laurate has a carbon content of biogenic origin of at least 90% by weight, relative to the total weight of carbon atoms.

[0024] According to one embodiment, the lubricating composition comprises, in addition to 1-methylheptyl laurate, at least one additive chosen from antioxidants, viscosity index-improving additives, pour point depressants, defoamers, corrosion inhibitors, antiwear and / or extreme pressure additives, friction modifiers, detergents, dispersants and mixtures thereof, more particularly chosen from antioxidants, pour point depressants, defoamers and corrosion inhibitors.

[0025] Preferably, the one or more additives represent 0.01 wt % to 20 wt %, preferably 0.1 wt % to 15 wt %, further preferably 0.5 wt % to 10 wt %, relative to the total weight of the lubricating composition.

[0026] The object of the present invention is precisely to improve the efficiency performance of a transmission in an internal combustion engine and of a reduction gear in an electric motor.

[0027] The invention therefore aims to improve the "fuel economy" performance of the internal combustion engine and to extend the duration of the autonomy of the electric motor-battery.

[0028] Other characteristics, variants and advantages of embodiments of the monoesters of the invention will become more apparent on reading the following description and examples, which are given as illustration of the invention but are not limiting thereof.

[0029] Hereinafter, the expressions “included between ... and ...,” “range from ... to ..." and “varies from ... to ..." are equivalent and mean to include the endpoints, unless otherwise specified.

[0030] Unless otherwise stated, the expression "comprising a" should be understood as "comprising at least one". BRIEF DESCRIPTION OF THE DRAWINGS

[0031] [ Figure 1 ] schematically illustrates an electric or hybrid vehicle propulsion system. DETAILED DESCRIPTION

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

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

[0034] 1-Methylheptyl laurate can be obtained by the esterification reaction of lauric acid with octan-2-ol.

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

[0036] Thus, preferably, 1-methylheptyl laurate has a carbon content of biogenic 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] Within the framework of the present invention, the carbon content of biogenic origin can be measured according to standard ASTM D6866.

[0038] 1-Methylheptyl laurate, also referred to as the monoester of the present invention, is used in lubricating compositions for transmissions.

[0039] Other base oils

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

[0041] The base oil optionally present in the lubricating composition according to the invention is suitably chosen according to its compatibility with the monoester used according to the invention.

[0042] There may be mixtures of several base oils present, for example mixtures of two, three or four base oils.

[0043] Preferably, the base oil or other base oil mixture used in the lubricating composition according to the invention may have a relative humidity of 1.5 to 8 mm, measured at 100° C. according to standard ASTM D445. 2 / s, especially 1.5 to 6.1 mm 2 / s, more particularly 1.5 to 4.1 mm 2 / s, even more particularly 1.5 to 2.1 mm 2 / s kinematic viscosity.

[0044] The base oil may be chosen from mineral or synthetic oils belonging to groups I to V of the categories defined according to the API classification (or equivalents according to the ATIEL classification), as shown in Table 1 below, or mixtures thereof.

[0045] [Table 1]

[0046]

[0047] Mineral base oils include any type of base oil obtained by atmospheric and vacuum distillation of crude oil followed by refining operations such as solvent extraction, deasphalting, solvent dewaxing, hydrotreating, hydrocracking, hydroisomerization and hydrofinishing.

[0048] Mixtures of synthetic oils, which may be of biological origin, and mineral oils may also be used.

[0049] There are generally no restrictions on the use of different further base oils for producing the lubricating composition, except that the composition preferably must have properties suitable for use in the propulsion system of an electric or hybrid vehicle, in particular with regard to viscosity index, sulphur content or oxidation resistance.

[0050] The base oil may further be chosen from synthetic oils, such as certain carboxylic acid esters and alcohol esters other than the diesters defined in the present invention, polyalphaolefins (PAO), and polyalkylene glycols (PAG) obtained by polymerizing or copolymerizing alkylene oxides containing 2 to 8 carbon atoms, in particular 2 to 4 carbon atoms.

[0051] The PAOs used as base oils are obtained, for example, from monomers containing from 4 to 32 carbon atoms, for example from octene or decene.

[0052] The weight average molecular weight of PAO can vary quite significantly. Preferably, the weight average molecular weight of PAO is less than 600Da. The weight average molecular weight of PAO can further be 100 to 600Da, 150 to 600Da, or further be 200 to 600Da.

[0053] For example, the PAOs used in the context of the present invention have a particle size of 1.5 to 8 mm measured at 100° C. according to standard ASTM D445. 2 / s kinematic viscosity, trademarked by Ineos 162. 164. 166 and 168 Commercial sales.

[0054] Advantageously, the further base oil(s) are selected from polyalphaolefins (PAOs).

[0055] The content of the auxiliary base oil present in the lubricating composition according to the invention can be adjusted by a person skilled in the art.

[0056] According to one embodiment, the composition according to the invention may comprise 5 to 95% by weight, preferably 50 to 95% by weight and preferably 60 to 90% by weight of one or more base oils different from the monoesters according to the invention, relative to the total weight of the composition.

[0057] additive

[0058] The lubricating composition according to the invention may further comprise one or more additives known to a person skilled in the art in the field of transmission lubrication, more particularly additives known to a person skilled in the art in the field of transmission lubrication for internal combustion engines and for propulsion systems of electric or hybrid vehicles.

[0059] The additives that may be incorporated into the composition according to the invention may be chosen from antioxidants, pour point depressants, defoamers, corrosion inhibitors, antiwear and / or extreme pressure additives, friction modifiers, detergents, dispersants and mixtures thereof, more particularly from antioxidants, pour point depressants, defoamers and corrosion inhibitors.

[0060] Preferably, the lubricating composition according to the present invention may further comprise one or more additives selected from antioxidants, defoamers, pour point improvers, viscosity index improvers and anti-corrosion agents.

[0061] Within the framework of using the lubricating composition of the invention as a multifunctional fluid, it may also be advantageous to add one or more additives selected from antiwear additives, friction modifiers, detergents, extreme pressure additives and dispersants, for example for cooling batteries and / or electronic power components, and for lubricating components of propulsion systems, such as transmissions in electric or hybrid vehicles.

[0062] It will be appreciated that the nature and amount of the additives are chosen so as not to affect the properties of the lubricating composition imparted by the monoester according to the invention.

[0063] Such additives may be introduced alone and / or as a mixture similar to additives already available for commercial lubricant formulations for commercial vehicle engines, having performance levels defined by ACEA (Association of European Automobile Manufacturers) and / or API (American Petroleum Institute) well known to those skilled in the art.

[0064] Said additive may be present in the lubricating composition according to the invention in a content less than or equal to 20% by weight, more particularly from 0.01 to 20% by weight, preferably from 0.1 to 15% by weight and preferably from 0.5 to 10% by weight relative to the total weight of the composition.

[0065] Therefore, the lubricating composition according to the invention may comprise at least one antioxidant additive.

[0066] Thus, according to one aspect of the invention, the invention relates to a lubricating composition, more particularly suitable for lubricating a transmission, more particularly a transmission of an internal combustion 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.

[0067] Antioxidant additives generally make it possible to delay the degradation of the composition in use. This degradation is most often seen in the formation of deposits, in the presence of sludge or in an increase in the viscosity of the composition.

[0068] Antioxidant additives are particularly useful as free radical inhibitors or destructors of hydroperoxides. Commonly used antioxidant additives include phenolic antioxidants, aminic antioxidant additives, phosphorus-sulfur antioxidant additives. Some such antioxidant additives, such as phosphorus-sulfur antioxidant additives, produce ash. Phenolic antioxidant additives may be ashless or in the form of neutral or alkaline metal salts. The antioxidant additive may be particularly selected from sterically hindered phenols, sterically hindered phenol esters and sterically hindered phenols containing thioether bridges, diphenylamine, esters of at least one C1-C 12 Alkyl partially substituted diphenylamines, N,N'-dialkyl-aryl-diamines and mixtures thereof.

[0069] Preferably, according to the present invention, the hindered phenol is selected from compounds comprising a phenolic group in which at least one of the carbon atoms adjacent to the carbon atom carrying the alcohol functional group is blocked by at least one C1-C 10 Alkyl, preferably C1-C6 alkyl, preferably C4 alkyl, preferably tert-butyl.

[0070] Amine compounds are another class of antioxidant additives which may be used optionally in combination with phenolic antioxidant additives. Examples of amine compounds are aromatic amines, such as those having the formula NR 4 R 5 R 6 Aromatic amines, where R 4 represents an aliphatic group or a possibly substituted aromatic group, R 5 represents a possibly substituted aromatic group, R 6 represents a hydrogen atom, an alkyl group, an aryl group or a group having the formula R 7 S(O) z R 8 A group in which R 7 represents an alkylene or alkenylene group, R 8 represents an alkyl group, an alkenyl group or an aryl group, and z is 0, 1 or 2.

[0071] Sulfuralkylphenols or alkali metal or alkaline earth metal salts thereof may also be used as antioxidant additives.

[0072] Another class of antioxidant additives are copper compounds, such as copper thiophosphates or dithiophosphates, copper salts and carboxylates, copper dithiocarbamates, copper sulfonates, copper phenates, copper acetylacetonate. Copper salts I and II, succinates or succinic anhydride salts can also be used.

[0073] Advantageously, the lubricating composition comprises at least one ashless antioxidant additive.

[0074] In the lubricating composition according to the present invention, the additive may be used in a proportion of 0.1 to 2 wt % relative to the total mass of the composition.

[0075] The lubricating composition according to the invention may also comprise at least one antiwear and / or extreme pressure additive.

[0076] Antiwear additives and extreme pressure additives protect surfaces subject to friction by forming a protective film that adsorbs onto the surface.

[0077] There are many types of anti-wear additives. Preferably, the anti-wear additive is selected from phosphorus-sulfur additives, such as metal alkylthiophosphates, more particularly zinc alkylthiophosphates, more particularly zinc dialkyldithiophosphates or ZnDTP. Preferred compounds have the formula Zn((SP(S)(OQ 2 )(OQ 3 ))2, where Q 2 and Q 3 -same or different- independently represent an alkyl group, preferably an alkyl group containing 1 to 18 carbon atoms.

[0078] Phosphate amines are also anti-wear additives that can be used in the lubricating composition according to the invention. However, the phosphorus provided by such additives can act as a poison in the catalytic system of the vehicle because it produces ash. This effect can be minimized by partially replacing the phosphate amines with additives that do not bring phosphorus, such as polysulfides, especially sulfur olefins.

[0079] The lubricating composition may comprise 0.01 to 6 wt %, preferably 0.05 to 4 wt %, more preferably 0.1 to 2 wt % of antiwear additives and extreme pressure additives relative to the total weight of the composition.

[0080] The lubricating composition according to the present invention may further comprise an antifoaming agent.

[0081] The defoaming agent may be selected from silicones.

[0082] The lubricating composition may comprise 0.01 wt % to 2 wt % or 0.01 wt % to 5 wt %, preferably 0.1 wt % to 1.5 wt % or 0.1 wt % to 2 wt % of the defoaming agent relative to the total weight of the composition.

[0083] The lubricating composition according to the invention may further comprise at least one friction modifier additive.

[0084] Friction modifier additives may be selected from compounds providing metal elements and ashless compounds. Compounds providing metal elements include complexes of transition metals such as Mo, Sb, Sn, Fe, Cu, Zn, whose ligands may be hydrocarbon compounds containing oxygen, nitrogen, sulfur or phosphorus atoms. Ashless friction modifier additives are generally of organic origin and may be selected from fatty acids and polyol monoesters, alkoxylated amines, alkoxylated fatty amines, fatty epoxides, fatty epoxide borate esters, fatty amine acids or fatty acid glycerides. According to the present invention, the fatty compound comprises at least one hydrocarbon moiety comprising 10 to 24 carbon atoms.

[0085] The lubricating composition may comprise from 0.01 to 2 wt. % or from 0.01 to 5 wt. %, preferably from 0.1 to 1.5 wt. % or from 0.1 to 2 wt. % of the friction modifier additive, relative to the total weight of the composition.

[0086] The lubricating composition according to the invention may contain at least one additive capable of improving the viscosity index of the lubricating composition ("viscosity index improver" in English).

[0087] As defined herein, "viscosity index improver" refers to a compound used to provide a lubricating composition with good cold resistance and minimum viscosity at high temperatures.

[0088] Examples of viscosity index improving polymers include polymer 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).

[0089] The lubricating composition according to the invention generally comprises 0.1 to 15 wt. % of viscosity index improver, relative to the total weight of the lubricating composition.

[0090] The lubricating composition according to the invention may comprise at least one detergent additive.

[0091] Detergent additives generally reduce the formation of deposits on the surfaces of metal parts by dissolving oxidation and combustion byproducts.

[0092] Detergent additives useful in lubricating compositions are generally known to those skilled in the art. The detergent additive may be an anionic compound comprising a lipophilic hydrocarbon portion and a hydrophilic head. The associated cation may be a metal cation of an alkali metal or an alkaline earth metal.

[0093] The detergent additive is preferably selected from alkali metal or alkaline earth metal salts of carboxylic acids, sulfonates, salicylates, naphthenates and phenates. The alkali metal and alkaline earth metal are preferably calcium, magnesium, sodium or barium.

[0094] Such metal salts typically include the metal in a stoichiometric amount or in excess (i.e., in a concentration greater than the stoichiometric amount). This is also true for overbased detergents; the excess metal that imparts the overbased character to the detergent additive is typically in the form of an oil-insoluble metal salt, such as a carbonate, hydroxide, oxalate, acetate, glutamate, preferably a carbonate.

[0095] The lubricating composition used according to the invention may comprise, for example, 2 to 4% by weight of detergent additives, relative to the total weight of the composition.

[0096] The lubricating composition used according to the present invention may further comprise at least one pour point depressant additive.

[0097] Pour point depressant additives generally improve the behavior of the composition under cold conditions by slowing down the formation of paraffin crystals.Examples of pour point depressant additives include polyalkyl methacrylates, polyacrylates, polyarylamide, polyalkylphenols, polyalkylnaphthalenes, alkylpolystyrenes.

[0098] The lubricating composition used according to the invention may, for example, comprise from 0.05 to 2% by weight of a pour point depressant additive, relative to the total weight of the composition.

[0099] Furthermore, the lubricating composition used according to the invention may comprise at least one dispersant.

[0100] The dispersant may be chosen from Mannich bases, succinimides and derivatives thereof.The lubricating composition used according to the invention may comprise, for example, 0.2 to 10% by weight of dispersant, relative to the total weight of the composition.

[0101] According to one particular embodiment, the lubricating composition used according to the invention comprises or is even formed from (i) at least one monoester according to the invention, and (ii) at least one additive selected from antioxidants, defoamers, pour point depressants, anticorrosives, antiwear and / or extreme pressure additives, friction modifiers, detergents, dispersants and mixtures thereof, preferably selected from antioxidants, pour point depressants, defoamers, anticorrosives and mixtures thereof.

[0102] Advantageously, the lubricating composition used according to the invention comprises (i) a monoester according to the invention and (ii) at least one antioxidant additive.

[0103] According to one embodiment, the lubricating composition used according to the invention comprises or even consists of:

[0104] - 5 to 50% by weight, preferably 10 to 40% by weight, of 1-methylheptyl laurate;

[0105] - 50 to 95% by weight, preferably 60 to 90% by weight, of one or more base oils different from 1-methylheptyl laurate,

[0106] - optionally 0.01 to 20 wt. %, preferably 0.1 to 15 wt. %, also preferably 0.5 to 10 wt. % of one or more additives selected from friction modifier additives, antiwear additives, extreme pressure additives, detergents, antioxidants, viscosity index (VI) improvers, pour point depressant additives (PPD), dispersants, defoamers, thickeners, corrosion inhibitors, copper passivators and mixtures thereof; and

[0107] The content is expressed relative to the total weight of the composition.

[0108] According to one embodiment, the lubricating composition used according to the invention comprises or even consists of:

[0109] - 5 to 45% by weight, preferably 10 to 40% by weight, of 1-methylheptyl laurate;

[0110] - 50 to 95% by weight, preferably 55 to 90% by weight, of one or more base oils different from 1-methylheptyl laurate,

[0111] - 0.01 wt. % to 20 wt. %, preferably 0.1 wt. % to 15 wt. %, and also preferably 0.5 wt. % to 10 wt. % of one or more additives selected from friction modifier additives, antiwear additives, extreme pressure additives, detergents, antioxidants, viscosity index (VI) improvers, pour point depressant additives (PPD), dispersants, defoamers, thickeners, corrosion inhibitors, copper passivators and mixtures thereof; and

[0112] The content is expressed relative to the total weight of the composition.

[0113] According to one embodiment, the lubricating composition used according to the invention comprises or even consists of:

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

[0115] - 50 to 95% by weight, preferably 55 to 90% by weight, of one or more base oils other than esters;

[0116] - optionally 0.01 to 20 wt. %, preferably 0.1 to 15 wt. %, also preferably 0.5 to 10 wt. % of one or more additives selected from friction modifier additives, antiwear additives, extreme pressure additives, detergents, antioxidants, viscosity index (VI) improvers, pour point depressant additives (PPD), dispersants, defoamers, thickeners, corrosion inhibitors, copper passivators and mixtures thereof; and

[0117] The content is expressed relative to the total weight of the composition.

[0118] According to one embodiment, the lubricating composition used according to the invention comprises or even consists of:

[0119] - 5 to 45% by weight, preferably 10 to 40% by weight, of 1-methylheptyl laurate;

[0120] - 50 to 95% by weight, preferably 55 to 90% by weight, of one or more base oils other than esters;

[0121] - 0.01 wt. % to 20 wt. %, preferably 0.1 wt. % to 15 wt. %, and also preferably 0.5 wt. % to 10 wt. % of one or more additives selected from friction modifier additives, antiwear additives, extreme pressure additives, detergents, antioxidants, viscosity index (VI) improvers, pour point depressant additives (PPD), dispersants, defoamers, thickeners, corrosion inhibitors, copper passivators and mixtures thereof; and

[0122] The content is expressed relative to the total weight of the composition.

[0123] According to one embodiment, the lubricating composition used according to the invention comprises or even consists of:

[0124] - 5 to 45% by weight, preferably 10 to 40% by weight, of 1-methylheptyl laurate;

[0125] - 50 to 95% by weight, preferably 55 to 90% by weight, of one or more base oils other than esters;

[0126] - 0.01 to 20% by weight, preferably 0.1 to 15% by weight, also preferably 0.5 to 10% by weight of one or more additives selected from antioxidants, pour point depressants, defoamers, anticorrosives and mixtures thereof; and

[0127] The content is expressed relative to the total weight of the composition.

[0128] According to one embodiment, the lubricating composition used according to the invention comprises or even consists of:

[0129] - 5 to 50% by weight, preferably 10 to 40% by weight, of 1-methylheptyl laurate;

[0130] - 50 to 95% by weight, preferably 55 to 90% by weight, of one or more mineral or synthetic base oils selected from Group I oils, Group II oils, Group III oils and Group IV oils and mixtures thereof;

[0131] - optionally 0.01 to 20 wt. %, preferably 0.1 to 15 wt. %, also preferably 0.5 to 10 wt. % of one or more additives selected from friction modifier additives, antiwear additives, extreme pressure additives, detergents, antioxidants, viscosity index (VI) improvers, pour point depressant additives (PPD), dispersants, defoamers, thickeners, corrosion inhibitors, copper passivators and mixtures thereof; and

[0132] The content is expressed relative to the total weight of the composition.

[0133] According to one embodiment, the lubricating composition used according to the invention comprises or even consists of:

[0134] - 5 to 45% by weight, preferably 10 to 40% by weight, of 1-methylheptyl laurate;

[0135] - 50 to 95% by weight, preferably 55 to 90% by weight, of one or more mineral or synthetic base oils selected from Group I oils, Group II oils, Group III oils and Group IV oils and mixtures thereof;

[0136] - 0.01 wt. % to 20 wt. %, preferably 0.1 wt. % to 15 wt. %, and also preferably 0.5 wt. % to 10 wt. % of one or more additives selected from friction modifier additives, antiwear additives, extreme pressure additives, detergents, antioxidants, viscosity index (VI) improvers, pour point depressant additives (PPD), dispersants, defoamers, thickeners, corrosion inhibitors, copper passivators and mixtures thereof; and

[0137] The content is expressed relative to the total weight of the composition.

[0138] According to one embodiment, the lubricating composition used according to the invention comprises or even consists of:

[0139] - 5 to 45% by weight, preferably 10 to 40% by weight, of 1-methylheptyl laurate;

[0140] - 50 to 95% by weight, preferably 55 to 90% by weight, of one or more mineral or synthetic base oils selected from Group I oils, Group II oils, Group III oils and Group IV oils and mixtures thereof;

[0141] - 0.01 to 20% by weight, preferably 0.1 to 15% by weight, and also preferably 0.5 to 10% by weight, of one or more additives selected from antioxidants, pour point depressants, defoamers, anticorrosives and mixtures thereof; and

[0142] The content is expressed relative to the total weight of the composition.

[0143] The lubricating composition used according to the invention advantageously has a relative humidity of 1 to 6 mm, measured at 100° C. according to standard ASTM D445. 2 / s, preferably 1 to 4 mm 2 / s kinematic viscosity.

[0144] The lubricating composition used according to the invention advantageously has a thermal conductivity of 2 to 20 mm, measured at 40° C. according to standard ASTM D445. 2 / s, preferably 3 to 10 mm 2 / s kinematic viscosity.

[0145] application

[0146] As described above, the lubricating composition according to the present invention can be used as a lubricating fluid for a transmission.

[0147] More particularly, the lubricating composition defined in the present invention is used to improve the efficiency properties of a transmission.

[0148] 1-Methylheptyl laurate improves the performance of transmissions when incorporated into lubricating compositions for lubricating transmissions.

[0149] 1-Methylheptyl laurate also improves the fuel saving properties, the so-called "fuel economy" properties, of lubricating compositions comprising said 1-methylheptyl laurate. In fact, 1-methylheptyl laurate serves to reduce the traction coefficient of lubricating compositions comprising said 1-methylheptyl laurate.

[0150] The transmission may be a transmission for an engine of an internal combustion vehicle and / or a transmission for a propulsion system of an electric or hybrid vehicle.

[0151] The transmission of the propulsion system of an electric or hybrid vehicle more particularly comprises a reduction gear.The monoester according to the invention is therefore most particularly used to improve the efficiency of a reduction gear in the propulsion system of an electric or hybrid vehicle.

[0152] like Figure 1 As schematically shown in , the propulsion system of an electric or hybrid vehicle comprises in particular an electric motor (1) component, a battery (2) and a transmission, and more particularly a reducer (3).

[0153] The electric motor generally comprises an electronic power component (11) connected to a stator (13) and a rotor (14). The stator comprises coils, more particularly copper coils, which are alternately supplied with electric current. In this way, a rotating magnetic field is generated. Such a rotor comprises coils or permanent magnets or other magnetic materials and is rotated by the rotating magnetic field.

[0154] The electronic power components (11), the stator (13) and the rotor (14) of the propulsion system (1) are components having a complex structure and generating a large amount of heat during motor operation.

[0155] The bearing (12) is usually integrated between the stator (13) and the rotor (14). The transmission, more specifically the reduction gear (3), is used to reduce the speed of the motor output and adjust the speed transmitted to the wheels, so that the speed of the vehicle can be controlled at the same time.

[0156] Advantageously, the lubricating composition defined in the present invention can be used to improve the efficiency of transmissions, more particularly for engines of internal combustion vehicles and for propulsion systems of electric or hybrid vehicles. More particularly, the lubricating composition defined in the present invention can be used to improve the efficiency of reduction gears of propulsion systems of electric or hybrid vehicles.

[0157] According to another aspect of the invention, the invention also relates to a method for lubricating at least one mechanical part of a transmission member of a motor vehicle, in particular a light or heavy vehicle, such as a gearbox, an axle, preferably a manual gearbox and a heavy axle, or a reduction gear of an electric or hybrid vehicle, the method comprising at least one step of contacting the mechanical part with at least one lubricating composition according to the invention.

[0158] The invention further relates to the use of the monoester according to the invention as defined above for reducing the traction coefficient of a lubricating composition for a transmission in a motor vehicle, more particularly a lubricant for a gearbox and / or for an axle, in particular for an axle of a heavy vehicle, or a lubricant for a reduction gear in an electric or hybrid vehicle.

[0159] Furthermore, as described above, the lubricating composition according to the present invention has excellent performance in reducing fuel consumption ("fuel economy" performance).

[0160] Advantageously, the lubricating composition according to the invention thus has a low traction coefficient.

[0161] The lubricating composition defined in the present invention may also be used for cooling an electric motor of an electric or hybrid vehicle, more particularly for cooling the power electronics and / or the rotor and / or the stator of the electric motor and / or the motor reduction gear.

[0162] The invention will now be described by the following examples which are of course given as illustration of the invention but not limiting thereof.

[0163] Example

[0164] The properties of the monoester according to the invention (E1), 2-octanol laurate, were compared with another monoester, 2-ethylhexanol laurate (E2).

[0165] 2-Ethylhexanol is not of bio-based origin, whereas 2-octanol used in the examples is of bio-based origin.

[0166] The kinematic viscosity at 40° C. (KV40) and the kinematic viscosity at 100° C. (KV100) are determined according to standard ASTM D445.

[0167] The mini pour point (mini PP) is measured according to standard ASTM D7346.

[0168] The viscosity index (VI) is measured according to ASTM D2270.

[0169] The tribological properties can be evaluated by testing on a PCs instruments brand MTM type tribometer (micro traction machine, also known as ball-plane). This test is used to evaluate the performance of a lubricant in terms of friction under mixed / restricted conditions depending on the applied load, pressure or speed conditions.

[0170] The traction coefficient of the lubricating composition tested was determined at 40°C, 100°C and 140°C by using a hardened steel ball of about 2 cm diameter, for example 1.905 cm diameter, on a hardened steel flat surface.

[0171] This device is used to move a steel ball and a steel plane relative to each other in order to determine the coefficient of friction of a given lubricating composition while varying various properties such as speed, load and temperature. The hardened steel surface has an AISI 52100 reference with a mirror finish and the ball also has an AISI 52100 reference and is made of hardened steel.

[0172] The applied load was 25N and the rotation speed varied from 20mm / s to 2500mm / s. (SRR (sliding-rolling ratio = 5%))

[0173] About 50 ml of the lubricating composition to be tested is added to the apparatus. The balls are engaged face to face, the balls and the plane being independently actuated to produce a mixed rolling / sliding contact.

[0174] The traction coefficient is measured and recorded with the aid of a force sensor.

[0175] Table 2 summarizes the measurement results of tribological properties at 40°C (40°C SRR5%), 100°C (100°C SRR5%) and 140°C (140°C SRR5%).

[0176] [Table 2]

[0177] E1 E2 KV40(cSt) 1.855 1.801 KV100(cSt) 5.31 5.086 mini PP(℃) -36 -33 VI 142 143 (40℃ SRR 5%) 0.01 0.021 (100℃ SRR 5%) 0.019 0.045 (140℃ SRR 5%) 0.019 0.038

[0178] As shown in the results of this table, the monoesters according to the invention have a better traction coefficient, i.e. a lower traction coefficient, than the comparative monoesters of the prior art. A lower traction coefficient will allow better gains in fuel economy (fuel economy) of internal combustion engines and better gains in battery autonomy of electric or hybrid vehicles.

Claims

1. Use of a composition comprising 1-methylheptyl laurate as a lubricating composition for a transmission.

2. The method according to claim 1, wherein the gear is used in a transmission in an internal combustion engine and / or in a reduction gear in an electric motor.

3. Use according to any one of claims 1 to 2 for increasing the efficiency of a transmission.

4. The method according to claim 1 for reducing the fuel consumption of a vehicle equipped with transmission components, in particular transmission components of a gearbox and / or axles, which are lubricated by the lubricating composition.

5. Use according to any one of claims 1 to 3 for improving the efficiency performance of a reduction gear in an electric motor.

6. The use according to any one of claims 1 to 3 or 5 for extending the driving time of a battery of an electric vehicle or a hybrid vehicle.

7. The use according to any one of claims 1 to 6, wherein The lubricating composition comprises 5 to 50 wt % of 1-methylheptyl laurate, preferably 10 to 40 wt % of 1-methylheptyl laurate, relative to the total weight of the lubricating composition.

8. The use according to any one of claims 1 to 7, wherein Relative to the total weight of the lubricating composition, the composition comprises: - 5 to 50% by weight, preferably 10 to 40% by weight, of 1-methylheptyl laurate, and 50% to 95% by weight, preferably 60% to 90% by weight, of one or more base oils different from 1-methylheptyl laurate.

9. The use according to any one of claims 1 to 8, wherein The kinematic viscosity of the lubricating composition at 100° C. is 1 to 6 mm 2 / s, preferably 1 to 4 mm 2 / s.

10. The use according to any one of claims 1 to 9, wherein 1-Methylheptyl laurate has a carbon content of biogenic origin of at least 90% by weight relative to the total weight of carbon atoms.

11. The use according to any one of claims 1 to 10, characterized in that In addition to 1-methylheptyl laurate, the lubricating composition comprises at least one additive selected from antioxidants, viscosity index-improving additives, pour point depressants, defoamers, corrosion inhibitors, antiwear and / or extreme pressure additives, friction modifiers, detergents, dispersants and mixtures thereof, more particularly selected from antioxidants, pour point depressants, defoamers and corrosion inhibitors.

12. The use according to claim 11, wherein The at least one additive accounts for 0.01 to 20 wt %, preferably 0.1 to 15 wt %, and more preferably 0.5 to 10 wt %, relative to the total weight of the lubricating composition.

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