Use of diesters in cooling and / or lubricating compositions for electric or hybrid vehicles

Abstract

The invention relates to the use of a composition for cooling and / or lubricating a propulsion system of an electric or hybrid vehicle, said composition comprising one or more diesters, each of which is formed between a diol containing 3 to 12 carbon atoms and two identical or different monocarboxylic acids, the monocarboxylic acid includes a linear or branched hydrocarbon chain having from 4 to 10 carbon atoms.

Description

Technical Field

[0001] The present invention relates to the field of compositions for cooling and / or lubricating propulsion systems of electric or hybrid vehicles, more particularly, compositions for cooling batteries and motor reducers, batteries and / or power electronic components of electric or hybrid vehicles. More particularly, the present invention aims to propose cooling compositions and their implementation in motors or motor reducers, batteries and power electronic components. Background Art

[0002] The evolution of international standards for reducing CO2 emissions and lowering energy consumption has prompted car manufacturers to come up with alternative solutions to the internal combustion engine.

[0003] One of the solutions identified by car manufacturers is to replace the internal combustion engine with an electric motor. Therefore, the research on reducing CO2 emissions has prompted many car companies to develop electric vehicles.

[0004] An "electric vehicle" as defined in the present invention refers to a vehicle including an electric motor as the sole propulsion device, while a hybrid vehicle includes an internal combustion engine and an electric motor as a combined propulsion device.

[0005] The term "propulsion system" as defined in the present invention refers to a system comprising the mechanical parts required to propel an electric vehicle. Thus, the propulsion system more particularly comprises an electric motor including a rotor-stator assembly of a power electronics system (dedicated to speed regulation), a transmission (also called a reducer, and when the reducer is connected to the motor, one speaks of a motor reducer) and a battery. The battery is usually composed of a group of storage cells called cells.

[0006] Generally speaking, in electric or hybrid vehicles, it is necessary to use a composition to meet the lubrication and / or cooling requirements of the various parts of the propulsion system described above.

[0007] More specifically, electric propulsion systems generate heat during their operation through the electric motors, power electronics and batteries. Since the heat generated is greater than what is usually dissipated to the environment, cooling must be provided for the motors, electronics and batteries. Generally, several heat generating parts of the propulsion system and / or heat sensitive parts of said system are cooled, in particular the power electronics and batteries, to prevent them from reaching dangerous temperatures.

[0008] Traditionally, it is known how to cool electric motors by air or water, optionally in combination with ethylene glycol. However, with the advent of smaller and more powerful engines, this cooling method is no longer sufficient. In addition, the heat that the battery can generate, especially during fast charging, cannot be extracted by the methods traditionally used.

[0009] Therefore, alternative methods of cooling and lubrication of propulsion systems, and more particularly batteries, have recently been proposed.

[0010] Lubricating compositions have therefore been proposed to perform the dual functions of lubrication and cooling.Lubricating compositions are generally composed of one or more base oils, which are usually associated with a variety of additives designed to stimulate the lubricating properties of the base oils, such as friction modifier additives.

[0011] For example, document WO 2018 / 078290 proposes using a composition comprising at least one polyalkylene glycol to cool and / or lubricate the motor system of an electric vehicle, the composition being obtained by polymerization or copolymerization of an alkylene oxide containing 2 to 8 carbon atoms.

[0012] The object of the present invention is precisely to propose a novel composition suitable for its implementation for cooling and / or lubricating the propulsion system of an electric vehicle or a hybrid vehicle, more particularly for cooling the motor or motor reducer, batteries and / or power electronic components, or in particular for lubricating the motor or motor reducer, or even only for the reducer. Summary of the invention

[0013] A subject of the present invention is therefore the use of a composition for cooling and / or lubricating a propulsion system of an electric or hybrid vehicle, the composition comprising one or more diesters, each of said diesters being formed between a diol having from 3 to 12 carbon atoms and two identical or different monocarboxylic acids comprising a linear or branched hydrocarbon chain having from 4 to 10 carbon atoms.

[0014] According to one embodiment, the composition comprises at least 5% by weight, preferably at least 10% by weight, further preferably at least 30% by weight, even more preferably at least 50% by weight or even at least 70% by weight of said one or more diesters or 100% by weight of said one or more diesters relative to the total weight of the composition.

[0015] Preferably, the composition comprises, relative to the total weight of the one or more diesters and the base oil other than the diester:

[0016] - 5 to 95% by weight, preferably 5 to 50% by weight, more preferably 10 to 40% by weight of said one or more diesters, and

[0017] - 5% to 95% by weight, preferably 50% to 95% by weight, preferably 60% to 90% by weight, of one or more base oils other than the diesters.

[0018] According to one embodiment, the composition is used for cooling batteries and / or power electronic components of electric or hybrid vehicles, more particularly lithium-ion batteries or nickel-cadmium batteries.

[0019] Preferably, the diester comprises from 13 to 25 carbon atoms; preferably from 15 to 24 carbon atoms.

[0020] Preferably, the kinematic viscosity of the diester at 100°C is 1 mm 2 / s to 6mm 2 / s, preferably within 1mm 2 / s to 4mm 2 / s range.

[0021] Preferably, at least one of the two hydroxyl functions of the diol is borne by a primary carbon atom.

[0022] Preferably, the diol is selected from 1,2-propylene glycol, 1,2-decanediol and 1,3-alkanediols having 3 to 10 carbon atoms.

[0023] Preferably, the diol is selected from 1,2-propylene glycol and 1,3-propylene glycol, preferably, the diol is 1,2-propylene glycol.

[0024] Preferably, the monocarboxylic acids, which may be the same or different, comprise a linear hydrocarbon chain having from 4 to 10 carbon atoms, preferably from 5 to 9 carbon atoms.

[0025] Preferably, in addition to the diester, the composition comprises at least one additive selected from antioxidants, pour point depressants, defoamers, preservatives, antiwear and / or extreme pressure additives, friction modifiers, detergents, dispersants and mixtures thereof, more particularly selected from antioxidants, pour point depressants, defoamers and preservatives.

[0026] According to one embodiment of the present invention, the present invention relates to the use of a composition for cooling and / or lubricating a propulsion system of an electric vehicle or a hybrid vehicle, the composition comprising one or more diesters selected from the following:

[0027] one or more diesters formed between a diol selected from 1,2-decanediol and 1,3-propylene glycol, and two identical or different monocarboxylic acids comprising a linear or branched hydrocarbon chain having from 4 to 10 carbon atoms,

[0028] - a diester formed from 1,2-propylene glycol and two heptanoic acids,

[0029] — a diester formed from 1,2-propylene glycol and two octanoic acids,

[0030] - a diester formed from 1,2-propylene glycol and two capric acids,

[0031] - a diester formed from 1,2-propylene glycol, caprylic acid and capric acid,

[0032] and mixtures thereof.

[0033] Other characteristics, variants and advantages of embodiments of the diesters according to the invention will become more apparent on reading the following description and examples, which are given as illustration of the invention but not as a limitation thereof.

[0034] In the following, unless otherwise stated, expressions such as “included between… and…,” “ranging from… to…,” and “varying from… to…” are equivalent and mean to include these limitations.

[0035] Unless otherwise specified, the expression "comprising a" should be understood as "comprising at least one".

[0036] BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 An electric or hybrid vehicle propulsion system is schematically shown. DETAILED DESCRIPTION

[0038] Firstly, the present invention relates to the use of a composition for cooling and / or lubricating a propulsion system of an electric or hybrid vehicle, the composition comprising one or more diesters, each of the diesters being formed between a diol having 3 to 12 carbon atoms and two identical or different monocarboxylic acids comprising a linear or branched hydrocarbon chain having 4 to 10 carbon atoms.

[0039] The invention also relates to the use of one or more diesters, each of which is formed between a diol having 3 to 12 carbon atoms and two identical or different monocarboxylic acids comprising a linear or branched hydrocarbon chain having 4 to 10 carbon atoms, for cooling and / or lubricating the propulsion system of an electric or hybrid vehicle.

[0040] The present invention may employ one or more diesters, each of which is formed between:

[0041] o a diol selected from 1,2-propylene glycol, 1,2-decanediol and a 1,3-diol having 3 to 10 carbon atoms, and

[0042] o Two identical or different monocarboxylic acids, including straight or branched hydrocarbon chains having 5 to 10 carbon atoms.

[0043] More particularly, the diester mixture can be prepared by reacting a mixture of diols with monocarboxylic acids.

[0044] For example, a diol can be reacted with three monocarboxylic acids A1, A2 and A3. Thus, according to this example, a diester mixture falling within the scope of the present invention may include:

[0045] - a diester formed between a diol and two acids A1,

[0046] - a diester formed between a diol and two acids A2,

[0047] - a diester formed between a diol and two acids A3,

[0048] - diesters formed between diols and acids A1 and A2,

[0049] - diesters formed between diols and acids A1 and A3,

[0050] - Diesters formed between diols and acids A2 and A3.

[0051] The diester used in the present invention

[0052] As stated above, the one or more diesters used in the present invention are formed between a diol and two monocarboxylic acids.

[0053] The "diester formed between a diol and two monocarboxylic acids" defined in the present invention refers to a compound obtained by two esterification reactions, each esterification reaction being carried out between one of the two alcohol functions of the diol and the acid function of one of the two monocarboxylic acids.

[0054] According to a preferred embodiment, the diester has from 13 to 25 carbon atoms, preferably from 15 to 24 carbon atoms.

[0055] The diols used in the present invention have from 3 to 12 carbon atoms. Preferably, at least one of the two hydroxyl functions of the diol is borne by a primary carbon atom.

[0056] When a carbon atom is bonded to only one other carbon atom, it is called a primary carbon atom.

[0057] According to one embodiment, the diol is chosen from 1,2-propylene glycol, 1,2-decanediol and 1,3-diols having 3 to 12 carbon atoms.

[0058] "Diol" refers to a compound that includes (exactly) two hydroxyl functions (-OH).

[0059] “1,3-diol comprising X to Y carbon atoms” refers to a diol whose alcohol functions are respectively located at positions 1 and 3 of the hydrocarbon chain comprising X to Y carbon atoms.

[0060] Preferably, the 1,3-diol is chosen from 1,3-diols having 3 to 10 carbon atoms, preferably having 3 to 7 carbon atoms.

[0061] "Hydrocarbon chain" as defined herein refers to a straight or branched, saturated or unsaturated alkyl or alkylene chain. The hydrocarbon chain may optionally be interrupted by one or more heteroatoms, more particularly by one or more oxygen atoms. Preferably, the hydrocarbon chain is a straight or branched, saturated or unsaturated alkyl or alkylene chain consisting of carbon atoms and hydrogen atoms.

[0062] According to one embodiment, the 1,3-diol having 3 to 12 carbon atoms is chosen from 1,3-alkanediols having 3 to 12 carbon atoms.

[0063] "1,3-alkanediol having X to Y carbon atoms" refers to a diol whose alcohol functions are located at positions 1 and 3, respectively, of an alkane chain having X to Y carbon atoms.

[0064] According to one embodiment, the diol is chosen from 1,2-propylene glycol, 1,2-decanediol and 1,3-diols having 3 to 7 carbon atoms, preferably from 1,2-propylene glycol and 1,3-alkanediols having 3 to 7 carbon atoms, more preferably from 1,2-propylene glycol and 1,3-propylene glycol, advantageously the diol is 1,2-propylene glycol.

[0065] The diols used in the present invention can be commercially available or synthesized according to any method known to those skilled in the art.

[0066] Preferably, the diols used according to the invention comprise a biogenic carbon content of at least 60 wt.-%, preferably at least 70 wt.-%, further preferably at least 80 wt.-%, further more preferably at least 90 wt.-%, relative to the total weight of the carbon atoms of the diol.

[0067] Within the framework of the present invention, the biogenic carbon content can be measured according to the ASTM D6866 standard.

[0068] The diesters used according to the invention are obtained from two identical or different monocarboxylic acids.

[0069] "Monocarboxylic acid" refers to a compound that includes a single carboxyl function (-COOH).

[0070] The hydroxycarboxylic acid used to form the diester of the present invention is selected from monocarboxylic acids comprising a linear hydrocarbon chain having 4 to 10 carbon atoms, preferably 5 to 9 carbon atoms, further preferably 5 to 8 carbon atoms. Preferably, the linear or branched hydrocarbon chain of the monocarboxylic acid is saturated.

[0071] According to one embodiment, the identical or different monocarboxylic acids comprise a linear hydrocarbon chain having 4 to 10 carbon atoms, preferably 5 to 9 carbon atoms, further preferably 5 to 8 carbon atoms.

[0072] According to one embodiment, the identical or different monocarboxylic acids comprise a saturated linear hydrocarbon chain having 5 to 10 carbon atoms, preferably 5 to 9 carbon atoms, further preferably 5 to 8 carbon atoms.

[0073] The monocarboxylic acid used in the present invention may be commercially available or synthesized according to any method known to those skilled in the art.

[0074] Preferably, the monocarboxylic acid used according to the invention comprises a carbon content of biogenic origin of at least 60% by weight, preferably at least 70% by weight, further preferably at least 80% by weight, further more preferably at least 90% by weight, relative to the total weight of carbon atoms of the diol.

[0075] Within the framework of the present invention, the biogenic carbon content can be measured according to the ASTM D6866 standard.

[0076] Preferably, the one or more diesters used in the present invention are saturated.

[0077] "Saturated diester" as defined in the present invention refers to a diester having a saturated hydrocarbon chain. Therefore, preferably, the diol used in the present invention comprises a saturated hydrocarbon chain, and the monocarboxylic acid used in the present invention each comprises a saturated hydrocarbon chain, preferably, the hydrocarbon chain consists of carbon atoms and hydrogen atoms.

[0078] According to a preferred embodiment, the diester used according to the invention is a branched diester.

[0079] "Branched diester" as defined herein refers to a diester having a branched hydrocarbon chain which may be positioned between the two ester functions of the diester and / or at one or both ends of the diester.

[0080] According to a preferred embodiment, the diester used in the present invention is saturated and branched.

[0081] According to one embodiment, the diester used in the present invention has a relative humidity of 1 mm2 measured at 100°C according to ASTM D445. 2 / s to 6mm 2 / s range, preferably within 1mm 2 / s to 4mm 2 Kinematic viscosity in the range of / s.

[0082] According to one embodiment, the diester according to the invention has a relative humidity at 2 mm2, measured at 40°C according to the ASTM D445 standard. 2 / s to 20mm 2 / s range, preferably within 3mm 2 / s to 10mm 2 Kinematic viscosity in the range of / s.

[0083] It will be appreciated that the definitions of carboxylic acids and alcohols given above may be combined as much as possible to define further specific embodiments.

[0084] The diester used according to the invention may more particularly correspond to the following formula (I):

[0085] [Chemical formula 1]

[0086]

[0087] in:

[0088] -R 1 denotes a linear or branched, saturated or unsaturated hydrocarbon chain having 3 to 9 carbon atoms, preferably saturated, preferably having 4 to 8 carbon atoms, preferably having 5 to 7 carbon atoms, said hydrocarbon chain being optionally interrupted by one or more heteroatoms, such as oxygen atoms, preferably consisting of carbon and hydrogen atoms;

[0089] -R 2 represents a linear or branched, saturated or unsaturated hydrocarbon chain having 4 to 9 carbon atoms, preferably saturated, said hydrocarbon chain being optionally interrupted by one or more heteroatoms, such as oxygen atoms, preferably consisting of carbon and hydrogen atoms; and

[0090] -R 3 It denotes a linear or branched, saturated or unsaturated hydrocarbon chain having 3 to 10 carbon atoms, which is preferably saturated, the hydrocarbon chain being optionally interrupted by one or more heteroatoms, such as oxygen atoms, preferably the hydrocarbon chain consisting of carbon and hydrogen atoms.

[0091] Preferably, the diester or diesters corresponding to formula (I) have from 13 to 25 carbon atoms, preferably from 15 to 24 carbon atoms.

[0092] According to a particular embodiment, the free radical R 3 Represents the following part: -CH(G 1 )-CH(G 2 )-,

[0093] Among them G 1 and G 2 G represents independently of one another a hydrogen atom or a linear or branched (preferably linear), saturated or unsaturated (preferably saturated) hydrocarbon chain having 1 to 8 carbon atoms, it being understood that 1 and G 2 It can't be all hydrogen.

[0094] Preferably, G 1 or G 2 One of them is a hydrogen atom.

[0095] According to one embodiment, the one or more diesters used in the present invention are selected from:

[0096] - a diester formed from 1,2-decanediol and two heptanoic acids,

[0097] - a diester formed from 1,2-decanediol and two valeric acids,

[0098] - a diester formed from 1,2-propylene glycol and two heptanoic acids,

[0099] - a diester formed from 1,2-propylene glycol and two nonanoic acids,

[0100] - a diester formed from 1,3-propanediol and two heptanoic acids,

[0101] - a diester formed from 1,2-propylene glycol and two octanoic acids,

[0102] - a diester formed from 1,2-propylene glycol and two capric acids,

[0103] - a diester formed from 1,2-propylene glycol, caprylic acid and capric acid,

[0104] and mixtures thereof.

[0105] The diesters according to the invention can be prepared according to synthesis methods known to those skilled in the art. The synthesis method more particularly uses two esterification reactions, each esterification reaction being carried out between an alcohol function of a diol and an acid function of a monocarboxylic acid.

[0106] Of course, a person skilled in the art will adjust the synthesis conditions in order to obtain the diesters according to the invention.

[0107] It will be appreciated that, within the framework of the present invention, the diester according to the invention may be in the form of a mixture of at least two diesters according to the invention, more particularly diesters as defined above.

[0108] Preferably, the diester used according to the invention comprises a biogenic carbon content of at least 60% by weight, preferably at least 70% by weight, further preferably at least 80% by weight, further more preferably at least 90% by weight, relative to the total weight of the carbon atoms of the diester.

[0109] Within the framework of the present invention, the biogenic carbon content can be measured according to the ASTM D6866 standard.

[0110] The diester or mixture of diesters according to the invention may represent at least 5% by weight, preferably at least 10% by weight, preferably at least 30% by weight, more preferably at least 50% by weight, further more preferably at least 70% by weight, more particularly at least 80% by weight, more particularly at least 90% by weight or even at least 95% by weight of the total weight of the composition used according to the invention.

[0111] The one or more diesters used in the present invention can be used together with one or more auxiliary base oils (also called common bases). According to one embodiment, relative to the total weight of the one or more diesters and the base oil different from the diester, the composition comprises:

[0112] - 5 to 95% by weight, preferably 5 to 50% by weight, more preferably 10 to 40% by weight, of one or more diesters according to the invention, and

[0113] - 5 to 95% by weight, preferably 50 to 95% by weight, preferably 60 to 90% by weight, of one or more different base oils according to the invention.

[0114] According to one embodiment, the composition used according to the invention may comprise at least 30% by weight of a diester or a mixture of diesters according to the invention, more particularly between 50% and 99.5% by weight, preferably between 70% and 99% by weight, more preferably between 80% and 99% by weight or even between 80% and 95% by weight, relative to the total weight of the composition.

[0115] According to a particular embodiment, the cooling and / or lubricating composition according to the invention may be formed with more than 95% by weight, more particularly more than 98% by weight, or even with 100% by weight of one or more diesters according to the invention.

[0116] According to a particular embodiment, the cooling composition used according to the invention will comprise 100% by weight of a mixture of diesters as defined according to the invention and one or more auxiliary base oils, preferably in a proportion such that the composition comprises, relative to the total weight of the cooling composition:

[0117] - 5 to 95% by weight, preferably 5 to 50% by weight, more preferably 10 to 40% by weight, of one or more diesters according to the invention, and

[0118] - 5 to 95% by weight, preferably 50 to 95% by weight, preferably 60 to 90% by weight, of one or more different base oils according to the invention.

[0119] Auxiliary base oil

[0120] The cooling and / or lubricating composition used according to the invention may also comprise, in addition to one or more diesters according to the invention, one or more base oils which are different from the diesters according to the invention.

[0121] The one or more base oils present (again where appropriate) in the cooling and / or lubricating composition according to the invention are suitably chosen with regard to their compatibility with the one or more diesters used according to the invention.

[0122] There may be mixtures of various base oils, for example mixtures of two, three or four base oils.

[0123] Preferably, the base oil or the mixture of auxiliary base oils used in the cooling composition according to the present invention may have a relative humidity at 1.5 mm2 measured at 100°C according to ASTM D445 standard. 2 / s to 8mm 2 / s range, especially within 1.5mm 2 / s to 6.1mm 2 / s range, more particularly within 1.5 mm 2 / s to 4.1mm 2 / s, even more particularly in the range of 1.5 mm 2 / s to 2.1mm 2 Kinematic viscosity in the range of / s.

[0124] The base oil may be chosen from mineral or synthetic oils belonging to Group I to Group V of the categories defined according to the API classification (or their equivalents according to the ATIEL classification) and shown in Table 1 below, or mixtures thereof.

[0125] Table 1

[0126]

[0127] Mineral base oils include any type of base oil obtained by atmospheric and vacuum distillation of crude oil and subsequent refining operations such as solvent extraction, deasphalting, solvent dewaxing, hydrotreating, hydrocracking, hydroisomerization and hydrofinishing.

[0128] Mixtures of synthetic oils, which may be of biological origin, and mineral oils may also be used.

[0129] There are generally no restrictions on the use of different additional base oils for producing the cooling and / or lubricating composition, but the composition must have properties suitable for use in the propulsion system of an electric or hybrid vehicle, in particular viscosity index, sulphur content or oxidation resistance.

[0130] The base oil may also be chosen from synthetic oils (for example certain carboxylic acid esters and alcohol esters other than the diesters defined in the present invention), polyalphaolefins (PAO) and polyalkylene glycols (PAG) obtained by polymerization or copolymerization of alkylene oxides containing from 2 to 8 carbon atoms, more particularly from 2 to 4 carbon atoms.

[0131] The PAOs used as base oils are obtained, for example, from monomers comprising 4 to 32 carbon atoms, for example from octene or decene.

[0132] The weight average molecular weight of PAO can vary greatly. Preferably, the weight average molecular weight of PAO is less than 600Da. The weight average molecular weight of PAO can also be in the range of 100Da to 600Da, 150Da to 600Da, or further 200Da to 600Da.

[0133] For example, the PAO used in the context of the present invention has a PAO density at 1.5 mm measured at 100° C. according to the ASTM D445 standard. 2 / s to 8mm 2 Kinematic viscosities in the range of / s are commercially available from Ineos under the trademark and

[0134] Advantageously, the additional base oil or oils are selected from polyalphaolefins (PAOs).

[0135] The person skilled in the art adjusts the content of the one or more auxiliary base oils present in the cooling and / or lubricating composition according to the invention.

[0136] According to one embodiment, the composition according to the invention may comprise from 5% to 95% by weight, preferentially from 50% to 95% by weight, further preferentially from 60% to 90% by weight, of one or more base oils different from the diesters according to the invention, relative to the total weight of the composition.

[0137] additive

[0138] The cooling and / or lubricating composition according to the invention may also comprise one or more additives known to a person skilled in the art of lubricating and / or cooling the propulsion system of an electric or hybrid vehicle.

[0139] The additives that may be included in the composition according to the invention may be chosen from antioxidants, pour point depressants, defoamers, preservatives, antiwear agents and / or extreme pressure additives, friction modifiers, detergents, dispersants and mixtures thereof, more particularly, the additives are chosen from antioxidants, pour point depressants, defoamers and preservatives.

[0140] Preferably, the cooling and / or lubricating composition according to the present invention may further comprise one or more additives selected from antioxidants, defoamers, pour point improvers and corrosion inhibitors.

[0141] Within the framework of the use of the cooling composition according to the invention as a multifunctional fluid, for example for cooling batteries and / or power electronic components and for lubricating parts of the propulsion system in electric or hybrid vehicles, such as the transmission, the addition of one or more additives selected from antiwear additives, friction modifiers, detergents, extreme pressure additives and dispersants may also prove to be advantageous.

[0142] It will be appreciated that the nature and amount of the additives used are chosen so as not to affect the properties imparted by the diesters according to the invention to the cooling and / or lubricating composition.

[0143] Such additives may be introduced alone and / or as a mixture of additives similar to those already sold in commercial lubricant formulations for vehicle engines, with performance levels defined by ACEA (European Automobile Manufacturers Association) and / or API (American Petroleum Institute), as is well known to those skilled in the art.

[0144] The content of the one or more additives in the cooling and / or lubricating composition according to the invention may be less than or equal to 10% by weight, more particularly less than or equal to 5% by weight and more particularly within the range of 0.01% to 3% by weight relative to the total weight of the composition.

[0145] Therefore, the cooling and / or lubricating composition used in accordance with the invention may include at least one antioxidant additive.

[0146] According to another aspect of the invention, the present invention also relates to a cooling and / or lubricating composition, which is more particularly suitable for cooling a propulsion system, more particularly cooling an electric motor or an electric motor reducer, a battery and / or power electronic components of an electric or hybrid vehicle, said composition comprising (i) at least one diester as defined above, and (ii) at least one antioxidant additive.

[0147] Antioxidant additives generally retard the degradation of the composition in use. In the presence of sludge or increased viscosity of the composition, such degradation may significantly lead to the formation of deposits.

[0148] Antioxidant additives act in particular as free radical inhibitors or destroyers of hydroperoxides. Commonly used antioxidant additives include phenolic antioxidants, amine antioxidant additives, phosphorus-sulfur antioxidant additives. Some such antioxidant additives, such as phosphorus-sulfur antioxidant additives, produce ash. Phenolic antioxidant additives may be ash-free 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 phenolic aldehydes containing thioether bridges, diphenylamines, esters of at least one C1-C 12 Alkyl partially substituted diphenylamines, N,N'-dialkyl-aryl-diamines and mixtures thereof.

[0149] Preferably, according to the invention, the sterically hindered phenol is chosen from compounds comprising a phenolic moiety in which at least one adjacent carbon atom to the carbon atom bearing the alcohol function is replaced by at least one C1-C 10 The alkyl group is partially substituted, preferably with a C1-C6 alkyl group, preferably with a C4 alkyl group, and preferably with a tert-butyl group.

[0150] Amine compounds are another class of antioxidant additives that can be used in combination with phenolic antioxidant additives. Examples of amine compounds are aromatic amines, such as those of formula NR 4 R 5 R 6 Aromatic amines, where R 4 represents an aliphatic moiety or an aromatic moiety which may be substituted, R 5 represents an aromatic moiety that may be substituted, R 6 represents a hydrogen atom, an alkyl moiety, an aryl moiety or a group having the formula R 7 S(O) z R 8 part, where R 7 represents an alkylene or alkenylene moiety, R 8 represents an alkyl moiety, an alkenyl moiety or an aryl moiety, and z is 0, 1 or 2.

[0151] Sulfuralkylphenols or alkali metal salts or alkaline earth metal salts thereof can also be used as antioxidant additives.

[0152] Another class of antioxidant additives are copper compounds, such as copper thio- or dithiophosphates, copper salts and carboxylates, copper dithiocarbamates, copper sulfonates, copper carbolate, copper acetylacetonate. Copper salts I and II, succinates or succinic anhydride salts can also be used.

[0153] Advantageously, the cooling and / or lubricating composition comprises at least one ashless antioxidant additive.

[0154] In the cooling composition according to the invention, the one or more additives are used in a proportion of 0.1 wt % to 2 wt % relative to the total weight of the composition.

[0155] The cooling and / or lubricating composition according to the invention may also comprise at least one antiwear agent and / or extreme pressure additive.

[0156] Anti-wear additives and extreme pressure additives protect surfaces subject to friction by forming a protective film that adsorbs to the surface.

[0157] 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 dialkyl dithiophosphates or ZnDTP. Preferred compounds have the formula Zn((SP(S)(OQ2 )(OQ 3 ))2, where the same or different Q 2 and Q 3 Independently represents an alkyl moiety, preferably an alkyl moiety comprising 1 to 18 carbon atoms.

[0158] Amine phosphates are also anti-wear additives that can be used in the lubricating compositions according to the invention. However, the phosphorus provided by such additives can act as a poison in the catalytic system of the vehicle because they produce ash. This effect can be minimized by partially replacing the amine phosphates with additives that do not contain phosphorus, such as polysulfides, especially sulfur olefins.

[0159] The cooling and / or 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.

[0160] The cooling and / or lubricating composition according to the invention may also comprise an antifoaming agent.

[0161] The defoaming agent may be selected from silicones.

[0162] The cooling and / or lubricating composition may comprise 0.01 to 2 wt % or 0.01 to 5 wt %, preferably 0.1 to 1.5 wt % or 0.1 to 2 wt % of antifoaming agent relative to the total weight of the composition.

[0163] The cooling and / or lubricating composition according to the invention may also comprise at least one friction modifier additive.

[0164] 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 including 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 epoxyborates, fatty amino acids or fatty acid glycerides. According to the present invention, the fatty compound includes at least one hydrocarbon portion containing 10 to 24 carbon atoms.

[0165] The cooling and / or lubricating composition may comprise 0.01 to 2 wt % or 0.01 to 5 wt %, preferably 0.1 to 1.5 wt % or 0.1 to 2 wt % of friction modifier additives relative to the total weight of the composition.

[0166] Advantageously, the cooling and / or lubricating composition does not contain any friction modifier additives, more particularly for use in cooling battery components.

[0167] The cooling and / or lubricating composition according to the invention may comprise at least one detergent additive.

[0168] Detergent additives generally reduce the formation of deposits on metal part surfaces by dissolving oxidation and combustion byproducts.

[0169] Detergent additives useful in cooling and / or 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.

[0170] 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.

[0171] Such metal salts generally include a stoichiometric amount or an excess of the metal, i.e., a concentration greater than the stoichiometric amount. This is also true for overbased detergents; the excess metal that gives the detergent additive an overbased character is generally in the form of an oil-insoluble metal salt, such as a carbonate, hydroxide, oxalate, acetate, glutamate, preferably a carbonate.

[0172] The cooling and / or lubricating composition may, for example, comprise from 2% to 4% by weight of detergent additives, relative to the total weight of the composition.

[0173] The cooling and / or lubricating composition may also include at least one pour point depressant additive.

[0174] Pour point depressant additives generally improve the properties of the composition under cold conditions by slowing down the formation of paraffin crystals. Examples of pour point depressant additives include polyalkyl methacrylates, polyacrylates, polyaramids, polyalkylphenols, polyalkylnaphthalenes, alkylated polystyrenes.

[0175] Furthermore, the cooling and / or lubricating composition may comprise at least one dispersant.

[0176] The dispersant may be selected from Mannich bases, succinimide and derivatives thereof. The cooling composition may comprise, for example, 0.2% to 10% by weight of the dispersant relative to the total weight of the composition.

[0177] According to a particular embodiment, the cooling and / or lubricating composition used according to the invention comprises or even consists of (i) at least one diester according to the invention and (ii) at least one additive selected from antioxidants, defoamers, pour point depressants, corrosion inhibitors, antiwear agents and / or extreme pressure additives, friction modifiers, detergents, dispersants and mixtures thereof, preferably selected from antioxidants, pour point depressants, defoamers and corrosion inhibitors.

[0178] Advantageously, the cooling and / or lubricating composition used according to the invention is formed from (i) at least one diester corresponding to one of the formulae (I) defined above and (ii) at least one antioxidant additive.

[0179] According to a particular embodiment, the cooling and / or lubricating composition used according to the invention comprises or even consists of:

[0180] - at least 5% by weight, preferably at least 10% by weight, preferably at least 30% by weight, preferably at least 50% by weight, more preferably at least 70% by weight or even at least 90% by weight of one or more diesters corresponding to formula (I);

[0181] - optionally, 0.01 to 20 wt. %, preferably 0.05 to 15 wt. %, more preferably 0.1 to 10 wt. %, further more preferably 0.5 to 7 wt. % or even 1 to 5 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 thickeners and mixtures thereof; and

[0182] - optionally, 5 to 94% by weight, preferably 10 to 94% by weight, preferably 15 to 90% by weight, of one or more base oils different from the diesters according to the invention,

[0183] The content is expressed relative to the total weight of the composition.

[0184] According to a particular embodiment, the cooling and / or lubricating composition used according to the invention comprises or even consists of:

[0185] - 5 to 95% by weight, preferably 5 to 50% by weight, further preferably 10 to 40% by weight, of the one or more diesters corresponding to formula (I);

[0186] - 5 to 95% by weight, preferably 50 to 95% by weight, preferably 60 to 90% by weight, of one or more different said diesters;

[0187] - optionally, 0.01 to 20 wt. %, preferably 0.05 to 15 wt. %, more preferably 0.1 to 10 wt. %, further more preferably 0.5 to 7 wt. % or even 1 to 5 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;

[0188] The content is expressed relative to the total weight of the composition.

[0189] According to a particular embodiment, the cooling and / or lubricating composition used according to the invention comprises or even consists of:

[0190] - 5 to 95% by weight, preferably 10 to 90% by weight, more preferably 20 to 80% by weight, even more preferably 30 to 70% by weight or even 40 to 60% by weight of one or more diesters corresponding to formula (I);

[0191] - optionally, 5 to 95% by weight, preferably 10 to 90% by weight, more preferably 20 to 80% by weight, further more preferably 30 to 70% by weight or even 40 to 60% by weight of one or more base oils different from the diesters;

[0192] - optionally, 0.01 to 20% by weight, preferably 0.05 to 15% by weight, more preferably 0.1 to 10% by weight, further more preferably 0.5 to 7% by weight or even 1 to 5% by weight of one or more additives other than the diester and other than the base oil or oils, the additives being 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;

[0193] The content is expressed relative to the total weight of the composition.

[0194] The cooling and / or lubricating composition used in the present invention advantageously has a relative humidity of 1 mm2 measured at 100°C according to ASTM D445. 2 / s to 6mm 2 / s range, preferably within 1mm 2 / s to 4mm 2 Kinematic viscosity in the range of / s.

[0195] The cooling and / or lubricating composition used in the present invention advantageously has a relative humidity of 2 mm2 measured at 40°C according to ASTM D445 standard. 2 / s to 20mm 2 / s range, preferably within 3mm 2 / s to 10mm 2 Kinematic viscosity in the range of / s.

[0196] application

[0197] As mentioned above, the composition according to the invention can be used as a cooling and / or lubricating fluid for the propulsion system of an electric or hybrid vehicle.

[0198] like Figure 1 As shown schematically, the propulsion system of an electric vehicle or a hybrid vehicle comprises in particular an electric motor (1), a battery (2) and a transmission, more particularly a speed reducer (3).

[0199] The electric motor generally comprises a power electronic 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. The rotor itself comprises coils or permanent magnets or other magnetic materials and is rotated by the rotating magnetic field.

[0200] The power electronic components (11), stator (13) and rotor (14) of the propulsion system (1) are parts with complex structures and generate a lot of heat during the operation of the motor. Therefore, cooling must be provided for the motor and the power electronic components.

[0201] The bearing (12) is usually integrated between the stator (13) and the rotor (14). The transmission, more specifically the reducer (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.

[0202] Advantageously, the composition according to the invention can be used to cool the battery of an electric or hybrid vehicle. More particularly, according to this embodiment, it is intended to be in direct contact with the battery.

[0203] Suitable batteries for the propulsion system of electric or hybrid vehicles include, in particular, lithium-ion batteries or nickel-cadmium batteries.

[0204] According to another aspect of the invention, the invention also relates to a method for cooling at least a portion of a propulsion system of an electric or hybrid vehicle, more particularly a battery, comprising at least one step of contacting at least said portion, in particular said battery, such as a lithium-ion battery or a nickel-cadmium battery, with a composition comprising at least one diester according to the invention as described above.

[0205] Bringing the cooling composition according to the present invention into contact with the battery may include immersing or semi-immersing the battery in the composition, or injecting the composition on the surface of the battery.

[0206] "Immersed" means that the entire battery is surrounded by the cooling composition according to the invention. "Semi-immersed" means that only part of the battery is in contact with the composition.

[0207] Cooling may be achieved by any method known to those skilled in the art.The cell may be immersed or semi-immersed (statically or cyclically) in the composition.

[0208] Examples of direct contact include cooling by injection, jet, spray, immersion or semi-immersion in a bath, or by forming a mist of the composition according to the invention on the battery under pressure and gravity.

[0209] Advantageously, the composition is injected into the area to be cooled of the propulsion system by means of a jet at a relatively high pressure. Advantageously, the shear forces generated by the injection can reduce the viscosity of the fluid in the injection zone compared to the kinematic viscosity at rest, thereby further increasing the cooling potential of the composition.

[0210] In addition, as described in document WO 2015 / 116496, an oil circulation system commonly used in electric motors can be used.

[0211] The composition according to the invention can also be used for cooling an electric motor of an electric or hybrid vehicle, more particularly for cooling power electronics and / or a rotor and / or a stator and / or a motor reducer of an electric motor.

[0212] The cooling composition according to the invention has particularly electrical insulating properties and is particularly suitable for electric vehicles or hybrid vehicles.

[0213] In addition to the cooling properties of the compositions according to the invention, it is also possible to utilize their lubricating properties.

[0214] Therefore, the composition according to the invention can be used simultaneously to lubricate different parts of the propulsion system of an electric or hybrid vehicle, more particularly the bearings between the rotor and the stator of the electric motor, or the transmission, more particularly the reducer, in an electric or hybrid vehicle.

[0215] In the case of such use, the cooling composition according to the invention advantageously also comprises one or more additives selected from antiwear additives, friction modifiers, detergents, dispersants, extreme pressure additives and mixtures thereof.

[0216] The present invention will now be described by way of the following examples which are, of course, illustrative of the present invention but not limiting thereof.

[0217] Example

[0218] Example 1: Preparation of test compounds

[0219] The following compounds were prepared:

[0220] - Diester A: Diester formed from 1,2-decanediol and two heptanoic acids

[0221] - Diester B: Diester formed from 1,2-decanediol and two valeric acids

[0222] - Diester C: Diester formed from 1,2-propylene glycol and two heptanoic acids

[0223] - Diester D: Diester formed from 1,2-propylene glycol and two nonanoic acids

[0224] - Diester E: Diester formed from 1,3-propanediol and two heptanoic acids

[0225] - Diester F: Diester mixture formed from 1,2-propylene glycol and bio-based fragments of C8-C10 acids

[0226] - monoesters formed from monocarboxylic acids having a saturated hydrocarbon chain containing 3 to 14 carbon atoms; and monoalcohols having a saturated hydrocarbon chain containing 3 to 14 carbon atoms.

[0227] The diesters and monoesters are prepared according to known methods for preparing esters.

[0228] Example 2: Viscosity Measurement

[0229] The kinematic viscosity at 100° C. (KV100) and the kinematic viscosity at 40° C. (KV40) of the compound of Example 1 were determined according to ASTM D445 standard.

[0230] Table 2 shows the viscosities.

[0231] Table 2

[0232] <![CDATA[KV100(mm 2 / s)]]> <![CDATA[KV40(mm 2 / s)]]> Diester A 2.38 7.916 Diester B 1.856 5.659 Diester C 1.55 4.236 Diester D 1.878 5.503 Diester E 1.7404 4.7422 Diester F 2.147 6.61 Monoester 1.8 5.2

[0233] All diesters used in the present invention have a viscosity of less than 4 mm at 100°C. 2 / s.

[0234] Example 3: Thermal conductivity measurement

[0235] The thermal conductivity of the compound described in Example 1 was determined at different temperatures according to the ASTM D7896-19 standard.

[0236] Table 3 shows the results.

[0237] Table 3

[0238]

[0239] The results show that the diester used in the present invention has good thermal properties, which makes the diester useful as a cooling fluid in the propulsion system of electric or hybrid vehicles.

[0240] Example 4: Minimum flash point measurement

[0241] The minimum flash point is measured according to ASTM D93Ac standard (Cleveland open cup method).

[0242] Table 4 shows the values.

[0243] Table 4

[0244]

[0245]

[0246] As shown by the values ​​in Table 4, the flash point is better when the diester is a branched diester. In fact, the diester formed from 1,2-propylene glycol has a lower flash point than the diester formed from 1,3-propylene glycol, with the same number of overall carbon atoms.

Claims

1. Use of a composition for cooling and / or lubricating a propulsion system of an electric or hybrid vehicle, the composition comprising one or more diesters, each of the diesters being formed between a diol comprising 3 to 12 carbon atoms and two identical or different monocarboxylic acids comprising a linear or branched hydrocarbon chain having 4 to 10 carbon atoms, the hydrocarbon chain optionally being interrupted by one or more heteroatoms.

2. The method according to claim 1, wherein the straight or branched hydrocarbon chain having 4 to 10 carbon atoms is a straight or branched, saturated or unsaturated alkyl or alkylene chain consisting of carbon atoms and hydrogen atoms.

3. Use according to claim 1 or 2, wherein the composition comprises at least 5% by weight, preferably at least 10% by weight, further preferably at least 30% by weight, even more preferably at least 50% by weight or even at least 70% by weight of the one or more diesters or 100% by weight of the one or more diesters, relative to the total weight of the composition.

4. The use according to claim 1 or 2, wherein the composition comprises, relative to the total weight of the one or more diesters and the base oil different from the diester: - 5 to 95% by weight, preferably 5 to 50% by weight, further preferably 10 to 40% by weight, of the one or more diesters, and - 5% to 95% by weight, preferably 50% to 95% by weight, preferably 60% to 90% by weight, of one or more base oils other than the diesters.

5. Use according to any one of claims 1 to 4, for cooling batteries and / or power electronic components of electric or hybrid vehicles, more particularly for cooling lithium-ion batteries or nickel-cadmium batteries.

6. Use according to any one of the preceding claims, wherein the diester has 13 to 25 carbon atoms, preferably 15 to 24 carbon atoms.

7. Use according to any one of the preceding claims, wherein the one or more diesters correspond to formula (I): [Chemical formula 1] in: —R 1 denotes a linear or branched, saturated or unsaturated hydrocarbon chain having 3 to 9 carbon atoms, preferably saturated, preferably having 4 to 8 carbon atoms, preferably having 5 to 7 carbon atoms, said hydrocarbon chain being optionally interrupted by one or more heteroatoms, such as oxygen atoms, preferably consisting of carbon and hydrogen atoms; —R 2 represents a linear or branched, saturated or unsaturated hydrocarbon chain having 4 to 9 carbon atoms, preferably saturated, the hydrocarbon chain being optionally interrupted by one or more heteroatoms, such as oxygen atoms, preferably consisting of carbon atoms and hydrogen atoms; and - R 3 It represents a linear or branched, saturated or unsaturated hydrocarbon chain having 3 to 10 carbon atoms, which is preferably saturated, the hydrocarbon chain being optionally interrupted by one or more heteroatoms, such as oxygen atoms, preferably, the hydrocarbon chain consisting of carbon atoms and hydrogen atoms.

8. The use according to any one of the preceding claims, wherein the diester has a kinematic viscosity at 100°C of 1 mm 2 / s to 6mm 2 / s range, preferably within 1mm 2 / s to 4mm 2 / s range.

9. Use according to any one of the preceding claims, wherein at least one of the two hydroxyl functions of the diol is carried by a primary carbon atom.

10. Use according to any one of the preceding claims, wherein the diol is chosen from 1,2-propylene glycol, 1,2-decanediol and 1,3-alkanediols comprising 3 to 10 carbon atoms.

11. Use according to any one of the preceding claims, wherein the diol is selected from 1,2-propylene glycol and 1,3-propylene glycol, preferably the diol is 1,2-propylene glycol.

12. Use according to any one of the preceding claims, wherein the identical or different monocarboxylic acids comprise a linear hydrocarbon chain having from 4 to 10 carbon atoms, preferably from 5 to 9 carbon atoms.

13. Use according to any one of the preceding claims, wherein the one or more diesters are selected from: one or more diesters formed between a diol selected from 1,2-decanediol and 1,3-propylene glycol, and two identical or different monocarboxylic acids comprising a linear or branched hydrocarbon chain having from 4 to 10 carbon atoms, - a diester formed from 1,2-propylene glycol and two heptanoic acids, — a diester formed from 1,2-propylene glycol and two octanoic acids, - a diester formed from 1,2-propylene glycol and two capric acids, - a diester formed from 1,2-propylene glycol, caprylic acid and capric acid, and mixtures thereof.

14. Use according to any one of the preceding claims, wherein the one or more diesters are selected from: — diester formed from 1,2-decanediol and two heptanoic acids, — diesters formed from 1,2-decanediol and two valeric acids, - a diester formed from 1,2-propylene glycol and two heptanoic acids, — diesters formed from 1,2-propylene glycol and two nonanoic acids, - a diester formed from 1,3-propanediol and two heptanoic acids, — a diester formed from 1,2-propylene glycol and two octanoic acids, - a diester formed from 1,2-propylene glycol and two capric acids, - a diester formed from 1,2-propylene glycol, caprylic acid and capric acid, and mixtures thereof.

15. Use according to any one of the preceding claims, characterized in that In addition to the diester, the composition further comprises at least one additive selected from antioxidants, pour point depressants, defoamers, preservatives, antiwear agents and / or extreme pressure agents, friction modifiers, detergents, dispersants and mixtures thereof, more particularly selected from antioxidants, pour point depressants, defoamers and preservatives.

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