Use of a monoester in a composition for cooling electronic devices

Abstract

The present invention relates to the use of a composition for cooling at least one electronic device, the composition comprising, relative to the total weight of said composition, at least 70% by mass 2-ethylhexyl laurate. The invention also relates to a method for cooling at least one electronic device, the method comprising at least one step of bringing into contact with the electronic device a composition comprising, relative to the total weight of said composition, at least 70% by mass 2-ethylhexyl laurate.

Description

[0001] Use of a monoester in a composition for cooling electronic devices

[0002] Technical field

[0003] The present invention relates to the field of cooling compositions, more particularly to the field of cooling compositions for electronic devices, in particular for cooling the powertrain of an electric or hybrid vehicle. It relates more particularly to the use of a monoester in a composition in order to cool and lubricate one or more elements of the powertrain of an electric vehicle, more specifically to cool and lubricate all the elements of the powertrain of an electric vehicle.

[0004] Prior art

[0005] The evolution of international standards for reducing CO2 emissions, but also for reducing energy consumption, is pushing car manufacturers to offer alternative solutions to combustion engines.

[0006] One solution 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.

[0007] 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.

[0008] For the purposes of the present invention, the term "propulsion system" or "powertrain" 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 and a battery. The battery itself is generally made up of a set of electrical accumulators, called cells. Generally speaking, it is necessary to implement, in electric or hybrid vehicles, compositions to meet the lubrication and / or cooling constraints of the various parts of the propulsion system mentioned above.

[0009] In particular, electric propulsion systems generate heat during operation via the electric motor, power electronics and batteries. Since the amount of heat generated is greater than the amount of heat normally dissipated to the environment, it is necessary to ensure cooling of the motor, power electronics and batteries. Generally, cooling is carried out on several parts of the propulsion system that generate heat and / or the parts of said system that are sensitive to heat, in order to avoid reaching dangerous temperatures, and in particular the power electronics and batteries.

[0010] Traditionally, electric motors have been cooled with air or water, possibly combined with glycol. However, with the advent of increasingly smaller and more powerful motors, these cooling methods are no longer sufficient. Furthermore, the heat generated by a battery, particularly during rapid charging, cannot be extracted using conventional methods.

[0011] Thus, alternative methods of cooling propulsion systems, particularly batteries, have recently been proposed.

[0012] In this respect, lubricating compositions have been proposed to ensure the dual function of lubrication and cooling. Lubricating compositions are conventionally composed of one or more base oils, to which are generally associated several additives dedicated to boosting the lubricating performance of the base oils, such as for example friction modifying additives. For example, document WO 2018 / 078290 proposes to use, for cooling and / or lubricating a motorization system of an electric vehicle, a composition comprising at least one polyalkylene glycol obtained by polymerization or copolymerization of alkylene oxides comprising from 2 to 8 carbon atoms.

[0013] Despite the implementation of a cooling system, the risk of the battery overheating cannot be completely ruled out, for example in the case of a defective cell, or during an accident during which a cell may be pierced. This can even lead to an explosion and a global fire of the battery, known as the "runaway effect". Such overheating is particularly feared in the context of the operation of a Li-ion battery. Safety tests (UN RE100 standard) must therefore be conducted on batteries before they are marketed.

[0014] Therefore, it is desirable that the properties of the cooling fluid used in the propulsion systems of electric or hybrid vehicles, and in particular in the batteries and / or power electronics, are maintained, even at the high temperatures likely to be reached in the event of overheating of the battery.

[0015] The invention aims specifically to propose a monoester having excellent cooling properties for cooling electronic devices likely to increase in temperature during their operation.

[0016] Summary of the invention

[0017] The present invention thus relates to the use of a composition comprising 2-ethylhexyl laurate, as a cooling composition for at least one electronic device.

[0018] The present invention relates to the use of 2-ethylhexyl laurate in compositions for cooling electronic devices.

[0019] More particularly, an object of the invention is the use of a composition comprising at least 70% by mass of 2-ethylhexyl laurate, relative to the total mass of the composition as a cooling composition for at least one electronic device.

[0020] Preferably, the electronic device is selected from energy storage devices, power electronics, photovoltaic panels, cables, high-power chargers, electric motors, data centers, high-power computers, electric charging stations, stationary electricity storage devices, transformers, concentrated solar power devices, heat storage devices, antennas, medical devices, switching devices, chargers, computers, aeronautical electronics, computer electronics, inverters, rectifiers, converters and electric motor controllers. Preferably, the electronic device is at least one element of a propulsion system of an electric or hybrid vehicle.

[0021] According to one embodiment, the composition is used as a cooling and lubricating composition for at least one element of a propulsion system of an electric or hybrid vehicle.

[0022] Preferably, the cooling and lubricating composition is implemented as the sole fluid throughout the propulsion system of an electric or hybrid vehicle.

[0023] According to one embodiment, the composition is used to improve the efficiency of reducers in electric motors.

[0024] According to one embodiment, the composition is used to extend the battery life of an electric or hybrid vehicle.

[0025] Preferably, the composition comprises at least 70% by mass of 2-ethylhexyl laurate, at least 80% by mass, at least 90% by mass, or even at least 95% by mass of 2-ethylhexyl laurate relative to the total mass of the composition.

[0026] According to one embodiment, the composition comprises: from 70 to 95% by mass, preferably from 80 to 95% by mass, of 2-ethylhexyl laurate, and from 5 to 30% by mass, preferably from 5 to 20% by mass, of one or more base oils other than 2-ethylhexyl laurate, relative to the total mass of the composition.

[0027] Preferably, the 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.

[0028] According to one embodiment, said composition comprises, in addition to 2-ethylhexyl laurate, at least one additive 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.

[0029] 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 composition. The invention also relates to a method for cooling at least one electronic device, said method comprising at least one step of bringing a composition comprising 2-ethylhexyl laurate into contact with said electronic device.

[0030] Another subject of the invention is therefore a method for cooling at least one electronic device, said method comprising at least one step of bringing a composition comprising at least 70% by mass, relative to the total mass of the composition, of 2-ethylhexyl laurate into contact with said electronic device.

[0031] Preferably, in the context of the cooling method according to the invention, the electronic device has one or more of the following characteristics:

[0032] - the electronic device is chosen from energy storage devices, power electronics, photovoltaic panels, cables, high-power chargers, electric motors, data centers, high-power computers, electric charging stations, stationary electricity storage devices, transformers, concentrated solar energy devices, heat storage devices, antennas, medical devices, switching devices, chargers, computers, aeronautical electronics, computer electronics, inverters, rectifiers, converters and electric motor controllers;

[0033] - the electronic device is at least one element of a propulsion system of an electric or hybrid vehicle.

[0034] Preferably, in the context of the cooling method according to the invention, the composition has one or more of the following characteristics:

[0035] - the composition comprises at least 70% by mass, preferably at least 80% by mass, more preferably at least 90% by mass, or even at least 95% by mass of 2-ethylhexyl laurate, relative to the total mass of the composition;

[0036] - the composition comprises: o from 70% to 95% by mass, preferably from 80 to 95% by mass, of 2-ethylhexyl laurate, and o from 5 to 30% by mass, preferably from 5 to 20% by mass, of one or more base oils other than 2-ethylhexyl laurate, relative to the total mass of the composition;

[0037] - the 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 ;

[0038] - said composition comprises, in addition to 2-ethylhexyl laurate, at least one additive 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, 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 composition.

[0039] According to one embodiment of the cooling method according to the invention, the electronic device is a propulsion system of an electric or hybrid vehicle and in which the composition is brought into contact with the electric motor comprising the rotor-stator assembly of the power electronics, the transmission and the battery of said propulsion system.

[0040] The invention aims specifically to improve the cooling performance of compositions currently used to cool electronic devices.

[0041] The present invention also aims to improve, in addition to the cooling performance, the lubrication performance. Thus, the invention aims to propose a monoester which can be implemented in a composition implemented as a single fluid for the cooling and lubrication of all the elements of the powertrain of an electric or hybrid vehicle, advantageously electric. Other characteristics, variants and advantages of the implementation of a monoester according to the invention will become more apparent upon reading the description and examples which follow, given by way of illustration and not limitation of the invention.

[0042] 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.

[0043] Unless otherwise indicated, the expression “comprising a” should be understood as “comprising at least one”.

[0044] Brief description of the drawings

[0045] [Fig 1] schematically represents an electric or hybrid vehicle propulsion system.

[0046] Detailed description

[0047] Firstly, the invention relates to the use of 2-ethylhexyl laurate in a composition for cooling at least one electronic device.

[0048] The invention relates to the use of a composition comprising at least 70% by mass of 2-ethylhexyl laurate, relative to the total mass of the composition for cooling at least one electronic device.

[0049] 2-Ethylhexyl laurate can be obtained by esterification reaction between lauric acid and 2-ethylhexanol.

[0050] 2-Ethylhexyl laurate, also called monoester of the invention, is used in a cooling composition for at least one electronic device.

[0051] In the context of the invention, the composition comprising 2-ethylhexyl laurate is also called a cooling composition.

[0052] Additional base oil(s) The cooling 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.

[0053] Said base oil(s), optionally present in a cooling composition according to the invention, are chosen appropriately, with regard to their compatibility with the monoester used according to the invention.

[0054] It can be a mixture of several base oils, for example a mixture of two, three or four base oils.

[0055] Preferably, the base oil or mixture of additional base oils, used in a cooling 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.

[0056] 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.

[0057] [Table 1]

[0058] 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, dealphating, solvent dewaxing, hydrotreating, hydrocracking, hydroisomerization, and hydrofinishing. Blends of synthetic and mineral oils, which may be bio-based, may also be used.

[0059] There are generally no limitations on the use of additional different base oils to make cooling 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.

[0060] The base oils may also be chosen from synthetic oils, such as certain esters of carboxylic acids and alcohols, distinct from the diester defined according to the invention, from polyalphaolefins (PAO), and from polyalkylene glycols (PAG) obtained by polymerization or copolymerization of alkylene oxides comprising from 2 to 8 carbon atoms, in particular from 2 to 4 carbon atoms.

[0061] PAOs used as base oils are, for example, obtained from monomers containing 4 to 32 carbon atoms, for example from octene or decene.

[0062] 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.

[0063] 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.

[0064] Advantageously, the additional base oil or oils are chosen from polyalphaolefins (PAOs).

[0065] It is up to a person skilled in the art to adjust the content of additional base oil(s) present in a cooling composition according to the invention.

[0066] According to one embodiment, a composition implemented according to the invention may comprise from 5 to 30% by mass, preferably from 5 to 20% by mass of one or more base oils different from the monoester according to the invention, relative to the total mass of said composition. Additives

[0067] A cooling composition according to the invention may further comprise one or more additives known to those skilled in the art in the field of cooling and in particular in the field of cooling and lubrication of propulsion systems of electric or hybrid vehicles.

[0068] The additives that can be incorporated into a composition according to the invention can be chosen from friction modifying additives, anti-wear additives, extreme pressure additives, detergents, antioxidants, viscosity index (VI) improvers, pour point depressant (PPD) additives, dispersants, antifoaming agents, thickeners, corrosion inhibitors, copper passivating agents, and mixtures thereof.

[0069] In the context of the present invention, said additives are different from 2-ethylhexyl laurate and different from base oils.

[0070] Preferably, a cooling composition according to the invention may further comprise one or more additives chosen from antioxidants, antifoams, pour point improvers and anticorrosion agents.

[0071] 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 cooling 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.

[0072] It is understood that the nature and quantity of additives used are chosen so as not to affect the properties of the cooling composition conferred by the monoester according to the invention.

[0073] These additives may be introduced in isolation and / or in the form of a mixture similar to those already available for sale for formulations of commercial lubricants for vehicle engines, with a performance level 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. Said additive(s) may be present in the cooling composition according to the invention in a content of less than or equal to 10% by mass, in particular less than or equal to 5% by mass, and more particularly ranging from 0.01 to 3% by mass, relative to the total mass of said composition.

[0074] A cooling composition implemented according to the invention can thus comprise at least one antioxidant additive.

[0075] The invention thus relates, according to another of its aspects, to a cooling and optionally lubricating composition, in particular capable of cooling a propulsion system, in particular the engine or the geared motor, the battery and / or the power electronics of an electric or hybrid vehicle, said composition comprising (i) at least one monoester as defined previously, and (ii) at least one antioxidant additive.

[0076] The antioxidant additive generally helps to delay the degradation of the composition in service. This degradation can notably result in the formation of deposits, the presence of sludge or an increase in the viscosity of the composition.

[0077] 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.

[0078] Preferably according to the invention, the sterically hindered phenols are chosen from compounds comprising a phenol group in which at least one vicinal carbon of the carbon 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. Amino compounds are another class of antioxidant additives which can be used, optionally in combination with the phenolic antioxidant additives. Examples of amino compounds are aromatic amines, for example aromatic amines of 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.

[0079] Sulfurized alkyl phenols or their alkali and alkaline earth metal salts can also be used as antioxidant additives.

[0080] Another class of antioxidant additives is copper compounds, e.g. copper thio- or dithio-phosphates, copper salts of carboxylic acids, dithiocarbamates, sulphonates, phenates, copper acetylacetonates. Copper I and II salts, succinic acid or anhydride salts can also be used.

[0081] Advantageously, a cooling composition comprises at least one ash-free antioxidant additive.

[0082] Said additive(s) may be used, in a cooling composition according to the invention, at a rate of 0.1 to 2% by mass, relative to the total mass of the composition.

[0083] A cooling composition according to the invention may comprise at least one anti-wear and / or extreme pressure additive.

[0084] Anti-wear additives and extreme pressure additives protect friction surfaces by forming a protective film adsorbed on these surfaces.

[0085] 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.

[0086] 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.

[0087] A cooling 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 the composition.

[0088] A cooling composition according to the invention may also comprise at least one viscosity index (VI) improving additive.

[0089] Viscosity index improvers, particularly viscosity index improver polymers, help ensure good cold resistance and minimal viscosity at high temperatures.

[0090] Examples of viscosity index improving polymers include hydrogenated or non-hydrogenated polymeric esters, homopolymers or copolymers of styrene, butadiene and isoprene, homopolymers or copolymers of olefins, such as ethylene or propylene, polyacrylates and polymethacrylates (PMA), preferably homopolymers or copolymers of olefins, such as ethylene or propylene.

[0091] In particular, a cooling composition according to the invention may comprise from 1 to 15% by mass of additive(s) improving the viscosity index, preferably from 5% to 10% by mass, relative to the total mass of the cooling composition.

[0092] A cooling composition according to the invention may further comprise an antifoaming agent.

[0093] The antifoaming agent may be chosen from silicones. A cooling 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.

[0094] A cooling composition according to the invention may comprise at least one friction modifying additive.

[0095] 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.

[0096] A cooling 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.

[0097] Advantageously, a cooling composition is free of friction modifying additive, in particular for use in cooling the battery part.

[0098] A cooling composition according to the invention may comprise at least one detergent additive.

[0099] Detergent additives generally reduce the formation of deposits on the surface of metal parts by dissolving secondary oxidation and combustion products.

[0100] Detergent additives usable in a cooling 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.

[0101] 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.

[0102] 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.

[0103] A cooling composition may, for example, comprise from 2 to 4% by mass of detergent additive, relative to the total mass of the composition.

[0104] A cooling composition may also include at least one pour point depressant additive.

[0105] By slowing the formation of paraffin crystals, pour point depressants generally improve the cold behavior of the composition. Examples of pour point depressants include polyalkyl methacrylates, polyacrylates, polyarylamides, polyalkylphenols, polyalkylnaphthalenes, and alkylated polystyrenes.

[0106] Also, a cooling composition may include at least one dispersing agent.

[0107] The dispersing agent may be chosen from Mannich bases, succinimides and their derivatives. A cooling composition may, for example, comprise from 0.2 to 10% by mass of dispersing agent, relative to the total mass of the composition.

[0108] The cooling composition used according to the invention comprises at least 70% by mass of 2-ethylhexyl laurate, preferably at least 80% by mass of 2-ethylhexyl laurate, preferably at least 90% by mass, or even at least 95% by mass of 2-ethylhexyl laurate relative to the total mass of the composition.

[0109] Alternatively, the cooling composition used according to the invention may comprise 100% by mass of 2-ethylhexyl laurate, relative to the total mass of the composition.

[0110] According to a particular embodiment, a cooling composition implemented according to the invention comprises, or even consists of:

[0111] - from 70 to 95% by mass, preferably from 80 to 95% by mass, of 2-ethylhexyl laurate;

[0112] - from 5 to 30% by mass, preferably from 5 to 20% by mass, of one or more base oils other than 2-ethylhexyl laurate;

[0113] - 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, said additives being different from 2-ethylhexyl laurate and different from base oils; the contents being expressed relative to the total mass of said composition.

[0114] According to a particular embodiment, a cooling composition implemented according to the invention comprises, or even consists of:

[0115] - from 70% to 94% by mass, preferably from 80 to 94% by mass, of 2-ethylhexyl laurate;

[0116] - from 5 to 29% by mass, preferably from 5 to 19% by mass, of one or more base oils other than 2-ethylhexyl laurate;

[0117] - 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, said additives being different from 2-ethylhexyl laurate and different from base oils; the contents being expressed relative to the total mass of said composition.

[0118] According to a particular embodiment, a cooling composition implemented according to the invention comprises, or even consists of:

[0119] - from 70% to 94% by mass, preferably from 80 to 94% by mass, of 2-ethylhexyl laurate;

[0120] - from 5 to 29% by mass, preferably from 5 to 19% 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;

[0121] - 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, said additives being different from 2-ethylhexyl laurate and different from base oils; the contents being expressed relative to the total mass of said composition.

[0122] According to a particular embodiment, a cooling composition implemented according to the invention comprises, or even consists of:

[0123] - from 70% to 94% by mass, preferably from 80 to 94% by mass, of 2-ethylhexyl laurate;

[0124] - from 5 to 29% by mass, preferably from 5 to 19% 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;

[0125] - 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, said additives being different from 2-ethylhexyl laurate and different from base oils; the contents being expressed relative to the total mass of said composition.

[0126] A cooling 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.

[0127] A cooling 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 18 mm 2 / s.

[0128] Application

[0129] A composition defined in the invention may be implemented as a cooling fluid for cooling at least one electronic device, said electronic device preferably being chosen from energy storage devices, such as a battery, for example an electric or hybrid vehicle battery, power electronics, photovoltaic panels, cables, high-power chargers, electric motors, data centers, high-power computers, electric charging stations, stationary electricity storage devices, transformers, concentrated solar energy devices, heat storage devices, antennas, such as 5G antennas, medical devices, switching devices, chargers, computers, heat storage devices, aeronautical electronics, computer electronics, inverters, rectifiers, converters,for example DC / DC, DC / DC, AC / AC, DC / AC or AC / DC converters, and electric motor controllers, preferably among the propulsion systems of an electric or hybrid vehicle.,

[0130] More specifically, according to a particularly advantageous embodiment, a composition according to the invention can be used as a cooling and possibly lubricating fluid for a propulsion system of an electric or hybrid vehicle.

[0131] 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).

[0132] 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.

[0133] 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 operation of the motor. It is therefore imperative to ensure cooling of the electric motor and the power electronics.

[0134] 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.

[0135] Cooling may be implemented by immersion or semi-immersion of the electronic device in the cooling composition.

[0136] By "immersion" is meant that the entire electronic device is surrounded by the cooling composition according to the invention. By "semi-immersion" is meant that only a part of the electronic device is in contact with said composition.

[0137] Advantageously, a composition according to the invention can be used to cool the battery of an electric or hybrid vehicle. In particular, according to this embodiment, it is intended to be placed in direct contact with the battery. As batteries suitable for the propulsion systems of an electric or hybrid vehicle, mention may be made in particular of Li-ion batteries or nickel-cadmium batteries.

[0138] A composition according to 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.

[0139] The cooling composition according to the invention has in particular electrical insulation properties which are particularly satisfactory for use in electric or hybrid vehicles.

[0140] It is possible to take advantage, in addition to the cooling properties of a composition according to the invention, of its lubricating properties.

[0141] Thus, a composition according to the invention can simultaneously be used to lubricate the various parts of a propulsion system of an electric or hybrid vehicle, in particular bearings located between the rotor and the stator of an electric motor, or even the transmission, in particular the reducer, in an electric or hybrid vehicle, and to cool the elements of the propulsion system such as the battery and the power electronics for example.

[0142] In the case of such an application, a cooling composition according to the invention advantageously further comprises one or more additives chosen from anti-wear additives, friction modifiers, detergents, dispersants, extreme pressure additives, and mixtures thereof.

[0143] The present invention also relates to a method for cooling at least one electronic device, said method comprising at least one step of bringing a composition comprising at least 70% by mass, relative to the total mass of the composition, of 2-ethylhexyl laurate into contact with said electronic device. Typically, said electronic device will be put into operation and during this operation, said device may heat up. The cooling composition defined in the invention may then make it possible to cool said device during the cooling method according to the invention. All of the characteristics and embodiments defined in the context of the use apply to the cooling method according to the invention.In particular, the composition, called cooling composition, used in the cooling method according to the invention is as defined in the context of the use according to the invention.

[0144] In the context of the cooling method according to the invention, bringing the cooling composition according to the invention into contact with the electronic device(s) may consist of immersion or semi-immersion of said electronic device(s) in said composition or even of injection of said composition onto the surface of said electronic device(s).

[0145] By "immersion" is meant that the entire electronic device is surrounded by the cooling composition according to the invention. By "semi-immersion" is meant that only a part of the electronic device is in contact with said composition.

[0146] Cooling can be implemented by any method known to those skilled in the art. The electronic device can be immersed or semi-immersed, static or circulating, in said composition.

[0147] Examples of direct contact include cooling by injection, jet, spraying, immersion or semi-immersion in a bath, or by forming a mist from the composition according to the invention under pressure and by gravity on the electronic device.

[0148] Advantageously, the composition is injected by jet under fairly high pressure into the areas to be cooled of the electronic device, such as the propulsion system. Advantageously, the shear resulting from this injection makes it possible to reduce the viscosity of the fluid at the injection zone, compared to the kinematic viscosity at rest, and thus, to further increase the cooling potential of the composition.

[0149] Additionally, oil circulation systems commonly used in electric motors may be employed, as for example described in WO 2015 / 116496.

[0150] More particularly, the present invention relates to a method for cooling at least one element of a propulsion system of an electric or hybrid vehicle, said method comprising at least one step of bringing a composition comprising 2-ethylhexyl laurate into contact with at least one element of said propulsion system of an electric or hybrid vehicle.

[0151] According to this embodiment, bringing the cooling composition according to the invention into contact with the element(s) of a propulsion system of an electric or hybrid vehicle may consist of immersion or semi-immersion of said element(s) of a propulsion system of an electric or hybrid vehicle in said composition or even of injection of said composition onto the surface of said element(s) of a propulsion system of an electric or hybrid vehicle.

[0152] According to one embodiment, the cooling method comprises at least one step of bringing a battery, for example a lithium-ion or nickel-cadmium battery, into contact with a composition comprising 2-ethylhexyl laurate.

[0153] In the context of the cooling method according to the invention, bringing the cooling composition according to the invention into contact with the battery may consist of immersion or semi-immersion of the battery in said composition or even of injection of said composition onto the surface of the battery.

[0154] According to one embodiment, the invention relates to a method for cooling and lubricating at least one element of a propulsion system of an electric or hybrid vehicle, said method comprising at least one step of bringing a composition comprising 2-ethylhexyl laurate into contact with at least one element of said propulsion system of an electric or hybrid vehicle.

[0155] Preferably, the cooling and lubrication method according to the invention comprises bringing the cooling composition defined in the invention into contact with the electric motor comprising the rotor-stator assembly of the power electronics (dedicated to speed regulation), the transmission and the battery of said propulsion system of an electric or hybrid vehicle, advantageously electric.

[0156] All of the characteristics and embodiments defined in the context of the use apply to the cooling and lubrication method according to the invention. In particular, the composition, called cooling composition, used in the cooling and lubrication method according to the invention is as defined in the context of the use according to the invention. The invention will now be described by means of the following examples, given of course as illustrations and not as limitations of the invention.

[0157] Example

[0158] The compositions described in Table 2 were tested and compared. The proportions are mass proportions relative to the total mass of each composition.

[0159] [Table 2]

[0160] In Table 2:

[0161] Laurate 2-EH means 2-ethylhexyl laurate,

[0162] Group III oil means a Group III base oil, branched monoester means a monoester obtained from a carboxylic acid comprising a branched alkyl chain and an alcohol comprising a branched alkyl chain,

[0163] ADD1 is a package of additives including an antioxidant, an antifoam, a VI additive and an anti-wear,

[0164] ADD2 stands for antioxidant additive.

[0165] So far, the branched monoester implemented in the comparative composition CC2 is used as a reference for cooling applications since it is known to have good thermal properties. The thermal conductivity of the compounds described in Table 2 was determined according to ASTM D7896-19 at different temperatures.

[0166] The results are shown in Table 3.

[0167] [Table 3]

[0168] These results show that the composition comprising the monoester of the invention has very good thermal properties, which allows their use in a cooling composition.

[0169] 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.

[0170] The traction coefficient of the tested compositions is determined at 40°C and 80°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.

[0171] 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.

[0172] The applied load is 75 N and the rotation speed is 1 m / s. (SRR (slide-roll-ratio =20%)).

[0173] Approximately 50 ml of the tested lubricating composition was introduced into the device. The ball is engaged face against the plane, said ball and said plane being actuated independently so as to create a mixed rolling / sliding contact. The traction coefficient is measured and recorded via a force sensor.

[0174] Table 4 shows the results of the traction coefficient (TOC) measurements at 40°C and 80°C.

[0175] [Table 4]

[0176] As shown by the results in this Table 4, the monoester according to the invention has a better traction coefficient, i.e. a lower traction coefficient, than the comparative compositions of the state of the art. This lower traction coefficient will allow for better lubrication properties and thus a better gain in terms of battery autonomy for an electric or hybrid vehicle.

[0177] In summary of the above, the monoester of the invention has both very good cooling properties and very good lubricating properties, which makes it particularly well suited for use in a composition for cooling electronic devices but also for lubrication. Thus, the monoester of the invention can be advantageously used for cooling and lubricating the propulsion system of an electric or hybrid vehicle, in particular as the sole fluid in the entire propulsion system of an electric or hybrid vehicle, advantageously electric.

Claims

Claims 1. Use of a composition comprising at least 70% by mass of 2-ethylhexyl laurate, relative to the total mass of the composition, as a cooling composition for at least one electronic device.

2. Use according to claim 1, wherein the electronic device is chosen from energy storage devices, power electronics, photovoltaic panels, cables, high-power chargers, electric motors, data centers, high-power computers, electric charging stations, stationary electricity storage devices, transformers, concentrated solar energy devices, heat storage devices, antennas, medical devices, switching devices, chargers, computers, aeronautical electronics, computer electronics, inverters, rectifiers, converters and electric motor controllers.

3. Use according to any one of claims 1 to 2, in which the electronic device is at least one element of a propulsion system of an electric or hybrid vehicle.

4. Use according to any one of claims 1 to 3, as a cooling and lubricating composition for at least one element of a propulsion system of an electric or hybrid vehicle.

5. Use according to claim 4, wherein the cooling and lubricating composition is implemented as the sole fluid in the entire propulsion system of an electric or hybrid vehicle.

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

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

8. Use according to any one of claims 1 to 7, in which the 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.

9. Use according to any one of claims 1 to 8, characterized in that said composition comprises, in addition to 2-ethylhexyl laurate, at least one additive 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.

10. Use according to claim 9 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 composition.

11. Method for cooling at least one electronic device, said method comprising at least one step of bringing a composition comprising at least 70% by mass, relative to the total mass of the composition, of 2-ethylhexyl laurate into contact with said electronic device.

12. Method according to claim 11, wherein the electronic device is as defined in one of claims 2 or 3 and / or the composition is as defined in one of claims 8 to 9.

13. Method according to claim 11 or 12, wherein the electronic device is a propulsion system of an electric or hybrid vehicle and wherein the composition is brought into contact with the electric motor comprising the rotor-stator assembly of the power electronics, the transmission and the battery of said propulsion system.

Images