Use of a biodiesel in a cooling and / or lubrication composition of an electric or hybrid vehicle

Abstract

The present invention relates to the use, for cooling and / or lubricating a propulsion system of an electric or hybrid vehicle, of a composition comprising: at least one diester formed between: a pentanediol, and two monocarboxylic acids, identical or different, having a linear or branched hydrocarbon chain comprising 4 to 10 carbon atoms, said hydrocarbon chain optionally comprising one or more heteroatoms, such as a nitrogen or oxygen atom, and optionally at least one base oil distinct from the diester and / or at least one additive distinct from the diester, said additive being selected from friction modifiers, anti-wear additives, extreme pressure additives, detergents, antioxidants, viscosity index (VI) improvers, pour point depressants (PPD) additives, dispersants, antifoaming agents, thickeners, corrosion inhibitors, copper passivating agents,and their mixtures. Figure for the abbreviation: None,

Description

Title of the invention: Use of a biodiesel in a cooling and / or lubrication composition for an electric or hybrid vehicle. Technical field

[0001] The present invention relates to the field of compositions for cooling and / or lubricating a propulsion system of an electric or hybrid vehicle, and more particularly for cooling the motor or geared motor, the battery and / or the power electronics of an electric or hybrid vehicle. It aims in particular to provide a cooling composition compatible with its implementation at the level of a motor or geared motor, a battery and / or the power electronics. Previous technique

[0002] The evolution of international standards for the reduction of CO2 emissions, but also for the reduction of energy consumption, is pushing car manufacturers to offer alternative solutions to combustion engines.

[0003] One of the solutions identified by car manufacturers is to replace combustion engines with electric motors. Research into reducing CO2 emissions has therefore led to the development of electric vehicles by a number of automotive companies.

[0004] For the purposes of this invention, "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.

[0005] For the purposes of this invention, "propulsion system" means a system comprising the mechanical parts necessary for the propulsion of an electric vehicle. More specifically, the propulsion system includes an electric motor comprising the rotor-stator assembly of the power electronics (dedicated to speed regulation), a transmission (also called a gearbox, and when the gearbox is attached to the motor, it is then called a geared motor), and a battery. The battery itself generally consists of a set of electrical accumulators, called cells.

[0006] In general, it is necessary to implement, in electric or hybrid vehicles, compositions to meet the lubrication and / or cooling requirements of the various parts of the propulsion system mentioned above.

[0007] In particular, electric propulsion systems generate heat during operation via the electric motor, power electronics, and batteries. Since the amount of heat generated exceeds 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 on heat-sensitive parts of the system, in order to prevent dangerous temperatures from reaching the required levels, and in particular on the power electronics and batteries.

[0008] Traditionally, electric motors have been cooled by 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 dissipated using conventional methods.

[0009] Thus, alternative methods of cooling and lubricating propulsion systems, in particular batteries, have recently been proposed.

[0010] As such, lubricating compositions have been proposed to ensure the dual function of lubrication and cooling. Lubricating compositions are classically composed of one or more base oils, to which are generally added several additives designed to enhance the lubricating performance of the base oils, such as friction modifiers.

[0011] By way of example, document WO 2018 / 078290 proposes to implement, 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 2 to 8 carbon atoms.

[0012] The invention aims precisely to provide a new composition, suitable for implementation in the cooling and / or lubrication of propulsion systems of electric or hybrid vehicles, in particular for cooling the motor or geared motor, batteries and / or power electronics, or in particular for lubricating the motor or geared motor, or even the gearbox alone. Summary of the invention

[0013] The present invention thus relates to the use, for cooling and / or lubricating a propulsion system of an electric or hybrid vehicle, of a composition comprising: at least one diester formed between: • a pentanediol, and • two monocarboxylic acids, identical or different, comprising a linear or branched hydrocarbon chain having from 4 to 10 carbon atoms, said hydrocarbon chain possibly comprising one or more heteroatoms, such as a nitrogen or oxygen atom, and - possibly at least one base oil separate from the diester and / or at least one additive separate from the diester, said additive being selected from friction modifiers, anti-wear additives, extreme pressure additives, detergents, antioxidants, viscosity index (VI) improvers, pour point depressants (PPD) additives, dispersants, anti-foaming agents, thickeners, corrosion inhibitors, copper passivating agents, and mixtures thereof.

[0014] According to a preferred embodiment, the composition has one or more of the following characteristics: - pentanediol is 1,4-pentanediol, and / or - Pentanediol is derived from the reduction of a keto acid, preferably levulinic acid, said keto acid preferably being derived from vegetable raw materials, and / or - said diester has a kinematic viscosity at 100°C ranging from 1 to 6 mm² / s, preferably ranging from 1 to 4 mm² / s, and / or - said monocarboxylic acids, whether identical or different, comprise a linear alkyl chain having from 4 to 10 carbon atoms, preferably from 5 to 9 carbon atoms, or even from 5 to 8 carbon atoms, said alkyl chain possibly comprising one or more heteroatoms, for example one or more oxygen atoms, and / or - the said diester(s) is / are chosen from: • a diester formed from 1,4-pentanediol and two heptanoic acids, • a diester formed from 1,4-pentanediol and two pentanoic acids, • a diester formed from 1,4-pentanediol and two isovaleric acids, • a diester formed from 1,4-pentanediol and two levulinic acids, • a diester formed from 1,4-pentanediol and two nonanoic acids, • a diester formed from 1,4-pentanediol and two octanoic acids, • a diester formed from 1,4-pentanediol and two decanoic acids, • a diester formed from 1,4-pentanediol and octanoic acid and decanoic acid,

[0015] and mixtures thereof, and / or - the composition comprises, in relation to the total mass of the composition: • from 5 to 95% by mass, preferably from 10 to 90% by mass, preferably still from 20 to 80% by mass, even more preferably from 30 to 70% by mass, or even from 40 to 60% by mass of said diester(s), • from 1 to 95% by mass, preferably from 10 to 90% by mass, preferably even more from 20 to 80% by mass, even more preferably from 30 to 70% by mass, or even from 40 to 60% by mass of one or more base oils different from said diesters, • possibly from 0.01 to 20% by mass, preferably from 0.05 to 15% by mass, preferably still from 0.1 to 10% by mass, even more preferably from 0.5 to 7% by mass, or even from 1 to 5% by mass of one or more additives distinct from the biodiesel and distinct from the base oil(s), and / or - the composition comprises, in relation to the total mass of the composition: • at least 5% by mass, preferably at least 10% by mass, preferably at least 30% by mass, preferably at least 50% by mass, more preferably at least 70% by mass, or even at least 90% by mass, of one or more diesters; • from 0.01 to 20% by mass, preferably from 0.05 to 15% by mass, preferably still from 0.1 to 10% by mass, even more preferably from 0.5 to 7% by mass, or even from 1 to 5% by mass, of one or more additives chosen from among friction modifiers, anti-wear additives, extreme pressure additives, detergents, antioxidants, viscosity index (VI) improvers, pour point depressants (PPD) additives, dispersants, antifoaming agents, thickeners, corrosion inhibitors, copper passivating agents, and mixtures thereof; and • possibly from 5 to 94% by mass, preferably from 10 to 94% by mass, preferably from 15 to 90% by mass of separate base oil(s) from said diester, and / or - the biodiesel has a carbon content of biological origin of at least 60% by weight, preferably at least 75% by weight, preferably even more at least 90% by weight, or even at least 95% by weight, relative to the total weight of carbon atoms in said biodiesel, and / or - the composition comprises at least 5% by mass, preferably at least 10% by mass, preferably even more preferably at least 30% by mass, even more preferably at least 50% by mass, or even at least 70% by mass of said diester(s) or 100% by mass of said diester(s), relative to the total mass of the composition, and / or - the composition consists of one or more diesters and one or more base oils different from said diesters, preferably in a proportion such that the composition consists of: • 5 to 95% by mass, preferably 5 to 50% by mass, preferably still 10 to 40% by mass, of the biodiesel(s), and • 5 to 95% by mass, preferably 50 to 95% by mass, preferably 60 to 90% by mass, of one or more base oils different from the biodiesels, • relative to the total mass of the composition.

[0016] According to one embodiment, the composition according to the invention is used to cool the battery and / or the power electronics of an electric or hybrid vehicle, in particular a lithium-ion or nickel-cadmium battery.

[0017] According to one embodiment, the composition according to the invention is used to cool and / or to protect against thermal runaway a battery, preferably a lithium-ion battery.

[0018] According to one embodiment, the vehicle is an electric vehicle.

[0019] The diesters defined in the present invention can be used alone or in a composition with one or more other base oils and / or with one or more functional additives to lubricate and / or to cool elements of a propulsion system of an electric or hybrid vehicle, in particular an electric vehicle.

[0020] More specifically, the diesters defined in the present invention can be used to cool the battery of an electric or hybrid vehicle, in particular an electric one.

[0021] In addition, the diesters defined in the present invention exhibit excellent cold properties.

[0022] The diesters defined in the present invention make it possible to reduce the coefficient of traction and the coefficient of friction.

[0023] Finally, the diesters defined in the present invention exhibit good thermal conductivity showing the cooling capabilities of a diester-based lubricant composition according to the invention.

[0024] In the following text, the expressions "between ... and ...", "ranging from ... to ..." and "varying from ... to ..." are equivalent and are meant to mean that the limits are included, unless otherwise stated.

[0025] Unless otherwise indicated, the expression "including one" should be understood as "including at least one". Detailed description

[0026] Firstly, the invention relates to the use, for cooling and / or lubricating a propulsion system of an electric or hybrid vehicle, of a composition comprising one or more diesters, each of said diesters being formed between a pentanediol, preferably 1,4-pentanediol, and two monocarboxylic acids, identical or different, comprising a linear or branched hydrocarbon chain comprising 4 to 10 carbon atoms, said hydrocarbon chain possibly comprising one or more heteroatoms, such as a nitrogen or oxygen atom.

[0027] The invention also relates to the use, for cooling and / or lubricating a propulsion system of an electric or hybrid vehicle, of one or more diesters, each of said diesters being formed between a pentanediol, preferably 1,4-pentanediol, and two monocarboxylic acids, identical or different, comprising a linear or branched hydrocarbon chain comprising 4 to 10 carbon atoms, said hydrocarbon chain possibly comprising one or more heteroatoms, such as a nitrogen or oxygen atom.

[0028] Thus, the invention relates to a lubricating and / or cooling composition comprising: - at least one diester formed between: • a pentanediol, preferably 1,4-pentanediol, and • two monocarboxylic acids, identical or different, comprising a linear or branched hydrocarbon chain having from 4 to 10 carbon atoms, said hydrocarbon chain possibly comprising one or more heteroatoms, such as a nitrogen or oxygen atom,

[0029] said diester preferably having a carbon content of biological origin of at least 60% by weight, preferably of at least 75% by weight, preferably even of at least 90% by weight, or even of at least 95% by weight, relative to the total weight of the carbon atoms of said ester,

[0030] and - possibly at least one ingredient selected from the separate base oils of the diester, the separate additives of the diester, and mixtures thereof, where present said additive being preferably selected from friction modifier 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.

[0031] The lubricating composition according to the invention may comprise one or more diesters, each of said diesters being formed between: • a pentanediol, preferably 1,4-pentanediol, and • two monocarboxylic acids, identical or different, comprising a linear or branched hydrocarbon chain with 4 to 10 carbon atoms.

[0032] In particular, it is possible to prepare a mixture of diesters by reacting a pentanediol and a mixture of monocarboxylic acids.

[0033] For example, it is possible to react 1,4-pentanediol with three monocarboxylic acids A1, A2, and A3. Thus, according to this example, the mixture of diesters within the scope of the present invention is likely to comprise: - a diester formed between 1,4-pentanediol and two Al acids, - a diester formed between 1,4-pentanediol and two A2 acids, - a diester formed between 1,4-pentanediol and two A3 acids, - a diester formed between 1,4-pentanediol and an Al acid and an A2 acid, - a diester formed between 1,4-pentanediol and an Al acid and an A3 acid, - a diester formed between 1,4-pentanediol and an A2 acid and an A3 acid. Diester implemented according to the invention

[0034] As mentioned above, the diester(s) implemented according to the invention is / are formed between a pentanediol and two monocarboxylic acids.

[0035] By "diester formed between a pentanediol and two monocarboxylic acids" in the context of the present invention, we mean a compound obtained by two esterification reactions, each esterification reaction being carried out between one of the two alcohol functions of the pentanediol and the acid function of one of the two monocarboxylic acids.

[0036] According to one embodiment, the diester comprises 13 to 25 carbon atoms, preferably 15 to 23 carbon atoms or even 15 to 21 carbon atoms.

[0037] By "pentanediol" is meant a compound comprising (exactly) two hydroxyl functions (-OH) and five carbon atoms.

[0038] By "1,4-pentanediol" is meant a diol whose alcohol functions are located respectively in position 1 and in position 4 of an alkyl chain comprising 5 carbon atoms.

[0039] For the purposes of this invention, "hydrocarbon chain" means a linear or branched, saturated or unsaturated alkyl or alkylene chain. The linear or branched hydrocarbon chain may optionally comprise one or more heteroatoms, in particular one or more oxygen or nitrogen atoms. Preferably, the hydrocarbon chain is a linear or branched, saturated or unsaturated alkyl or alkylene chain composed of carbon and hydrogen atoms.

[0040] The diol implemented according to the invention may be commercially available or synthesized according to any method known to a person skilled in the art.

[0041] According to one embodiment, the diol used in the invention is obtained by reduction of a keto-acid, preferably by reduction of levulinic acid.

[0042] A “keto-acid” is a compound comprising a carboxylic acid function (-COOH) and a ketone function (>C=O).

[0043] Preferably, levulinic acid is derived from vegetable raw materials, such as cellulose or sugar.

[0044] Thus, preferably, the diol used in the invention is derived from plant-based raw materials, such as cellulose or sugar.

[0045] Preferably, the diol implemented according to the invention comprises a carbon content of biological origin of at least 60% by mass, preferably at least 75% by mass, preferably still at least 90% by mass, even more preferably at least 95% by mass, relative to the total mass of carbon atoms of the diol.

[0046] Within the framework of the present invention, the carbon content of biological origin can be measured according to the ASTM D6866 standard.

[0047] The diester implemented according to the invention is obtained from two identical or different monocarboxylic acids.

[0048] By “monocarboxylic acid” is meant a compound having a single carboxyl function (-COOH).

[0049] The carboxylic acids used to form a diester of the invention are selected from monocarboxylic acids, comprising a linear or branched hydrocarbon chain having from 4 to 10 carbon atoms, preferably from 5 to 9 carbon atoms, and even more preferably from 5 to 8 carbon atoms. Preferably, the linear or branched hydrocarbon chain of the monocarboxylic acids is saturated.

[0050] According to one embodiment, the monocarboxylic acids, identical or different, comprise a linear hydrocarbon chain consisting of 5 to 10 atoms of carbon, preferably with 5 to 9 carbon atoms or even 5 to 8 carbon atoms.

[0051] According to one embodiment, the monocarboxylic acids, identical or different, comprise a linear and saturated alkyl chain comprising 5 to 10 carbon atoms, preferably 5 to 9 carbon atoms or even 5 to 8 carbon atoms.

[0052] The monocarboxylic acids implemented according to the invention can be commercially available or synthesized by any method known to a person skilled in the art.

[0053] Preferably, the monocarboxylic acids implemented according to the invention comprise a biologically sourced carbon content of at least 60% by mass, preferably at least 75% by mass, more preferably at least 90% by mass, even more preferably at least 95% by mass, relative to the total mass of carbon atoms of the monocarboxylic acids.

[0054] Within the framework of the present invention, the biologically sourced carbon content can be measured according to ASTM D6866.

[0055] By way of example, the diesters according to the invention can be formed from a pentanediol, preferably 1,4-pentanediol, and a bio-based fraction comprising several monocarboxylic acids having from 4 to 10 carbon atoms, for example, a bio-based fraction comprising monocarboxylic acids having an alkyl chain having from 8 to 10 carbon atoms. According to this example, a mixture of diesters according to the invention is obtained and used in the composition of the invention.

[0056] Preferably, the diester implemented according to the invention is saturated.

[0057] For the purposes of this invention, "saturated diester" means a diester comprising saturated hydrocarbon chains. Thus, preferably, the monocarboxylic acids implemented according to the invention each comprise a saturated hydrocarbon chain, preferably, said hydrocarbon chain is made up of carbon and hydrogen atoms.

[0058] According to a particularly preferred embodiment, the diester used in the invention is a branched diester. It should be noted that in the case where the pentanediol is 1,4-pentanediol, the diester thus obtained will be a branched diester.

[0059] By "branched diester" in the sense of the invention, we mean a diester comprising a branched hydrocarbon chain which may be located between the two ester functions and / or at one or both ends of the diester.

[0060] According to a preferred embodiment, the diester implemented in the invention is saturated and branched.

[0061] According to one embodiment, the diester implemented according to the invention has a kinematic viscosity, measured at 100°C according to ASTM D445, ranging from 1 to 6 mm2 / s, preferably from 1 to 4 mm2 / s.

[0062] According to one embodiment, the diester implemented according to the invention has a kinematic viscosity, measured at 40°C according to ASTM D445, ranging from 2 to 20 mm2 / s, preferably from 3 to 18 mm2 / s.

[0063] It is understood that the definitions given above for carboxylic acid and alcohol can be combined, as far as possible, to define other particular embodiments.

[0064] A diester implemented according to the invention can more particularly correspond to formula (I):

[0065] [Chem.l] O

[0066] in which: - R1 represents a hydrocarbon chain, linear or branched, saturated or unsaturated, preferably saturated, having from 3 to 9 carbon atoms, preferably from 4 to 8 carbon atoms, preferably from 5 to 7 carbon atoms, said hydrocarbon chain being optionally interrupted by one or more heteroatoms, such as oxygen atoms, preferably the hydrocarbon chain being composed of carbon and hydrogen atoms; and - R2 represents a hydrocarbon chain, linear or branched, saturated or unsaturated, preferably saturated, having 3 to 9 carbon atoms, preferably 4 to 8 carbon atoms, preferably 5 to 7 carbon atoms, said hydrocarbon chain being optionally interrupted by one or more heteroatoms, such as oxygen atoms, preferably the hydrocarbon chain is made up of carbon and hydrogen atoms.

[0067] In the diester of formula (I), R1 and R2 may be identical or different.

[0068] According to one embodiment, R1 and R2 are chosen from alkyls comprising of 3 to 9 carbon atoms, linear or branched, possibly containing a ketone functional group (of type >=O). An example of a monocarboxylic acid that can lead to a diester of formula (I) in which R1 and / or R2 contain a carboxyl functional group is levulinic acid.

[0069] According to one embodiment, the diester(s) used according to the invention is / are chosen from: - a diester formed from 1,4-pentanediol and two heptanoic acids, - a diester formed from 1,4-pentanediol and two pentanoic acids, - a diester formed from 1,4-pentanediol and two isovaleric acids, - a diester formed from 1,4-pentanediol and two levulinic acids, - a diester formed from 1,4-pentanediol and two nonanoic acids, - a diester formed from 1,4-pentanediol and two octanoic acids, - a diester formed from 1,4-pentanediol and two decanoic acids, - a diester formed from 1,4-pentanediol and a mixture of acids comprising an octanoic acid and a decanoic acid,

[0070] and mixtures thereof.

[0071] It is understood that, within the framework of the present invention, a diester according to the invention may be in the form of a mixture of at least two diesters according to the invention, in particular as defined above.

[0072] Preferably, the diester implemented according to the invention comprises a carbon content of biological origin of at least 60% by mass, preferably at least 75% by mass, preferably still at least 90% by mass, even more preferably at least 95% by mass, relative to the total mass of carbon atoms of the diester.

[0073] Within the framework of the present invention, the carbon content of biological origin can be measured according to the ASTM D6866 standard.

[0074] Advantageously, the diesters according to the invention also have a high flash point, preferably a flash point of at least 120°C. The flash point can be measured according to ASTM D93Ac (open-cup Cleaveland method). According to certain embodiments, the flash point of the diesters can be at least 150°C or even at least 160°C. These high flash point values ​​can be obtained in particular when the diester is obtained from a monocarboxylic acid comprising a linear alkyl chain optionally substituted by a heteroatom, such as an oxygen atom.

[0075] The diester or mixture of diesters according to the invention can represent at least 5% by mass of the composition according to the invention, preferably at least 10% by mass, preferably at least 30% by mass, more preferably at least 50% by mass, even more preferably at least 70% by mass, in particular at least 80% by mass, more particularly at least 90% by mass, or even at least 95% by mass, or even 100% by mass, of the total mass of the composition according to the invention.

[0076] The diester(s) according to the invention can be used with one or more auxiliary base oils (also called co-bases). In this embodiment, preferably, the composition will comprise: - from 5 to 95% by mass, preferably from 5 to 50% by mass, preferably still 10 to 40% by mass, of the diester(s) according to the invention, and - from 5 to 95% by mass, preferably from 50 to 95% by mass, preferably from 60 to 90% by mass, of one or more base oils different from the diesters according to the invention,

[0077] in relation to the total mass of the diester(s) and base oils other than the diesters.

[0078] According to one embodiment, a lubricating composition according to the invention may comprise at least 30% by mass of a diester or mixture of diesters according to the invention, more particularly between 50% and 99.5% by mass, preferably between 70% and 99% by mass, more preferably between 80% and 99% by mass, or even between 80% and 95% by mass, relative to the total mass of said composition.

[0079] According to a particular embodiment, a lubricating composition according to the invention can be formed at more than 95% by mass, in particular at more than 98% by mass, of one or more diesters according to the invention, or even at 100% by mass of one or more diesters according to the invention.

[0080] According to a particular embodiment, the composition according to the invention is a composition comprising 100% by mass of a mixture of diester(s) defined in the invention and auxiliary base oil(s), preferably in a proportion such that the composition comprises: - from 5 to 95% by mass, preferably from 5 to 50% by mass, preferably still 10 to 40% by mass, of the diester(s) according to the invention, and - from 5 to 95% by mass, preferably from 50 to 95% by mass, preferably from 60 to 90% by mass, of one or more base oils different from the diesters according to the invention,

[0081] in relation to the total mass of the composition.

[0082] This embodiment is particularly advantageous when the composition is used for cooling, as a cooling fluid. Additional base oil(s) (co-base(s))

[0083] The lubricating composition according to the invention may include, in addition to one or more diesters according to the invention, one or more base oils distinct from the diesters according to the invention, referred to as "additional base oil".

[0084] The base oil(s), possibly present in the lubricating composition according to the invention, are chosen appropriately, with regard to their compatibility with the diester(s) used according to the invention.

[0085] It may be a mixture of several base oils, for example a mixture of two, three or four base oils.

[0086] Preferably, the base oil or mixture of auxiliary base oils, used in the lubricating composition according to the invention, can have a kinematic viscosity, measured at 100 °C according to ASTM D445, ranging from 1.5 to 8 mm2 / s, in particular from 1.5 to 6.1 mm2 / s, more particularly from 1.5 to 4.1 mm2 / s, even more particularly from 1.5 to 2.1 mm2 / s.

[0087] Base oils can be chosen from mineral or synthetic oils 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.

[0088] [Tables] Saturates content Sulfur content Viscosity index (VI) Group I (Mineral oils) <90% > 0.03% 80 <VI < 120 Groupement II (Huiles hydrocraquées) >90% <0.03% 80 <VI < 120 Groupement III (Huiles hydrocraquées ou hydro-isomérisées) >90% <0.03% >120 Group IV Polyalphaolefins (PAO) Group V Esters and other bases not included in groups I to IV

[0089] 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, desalpha removal, solvent dewaxing, hydrotreating, hydrocracking, hydroisomerization and hydrofinishing.

[0090] Mixtures of synthetic and mineral oils, which may be bio-based, may also be used.

[0091] Base oils can also be chosen from synthetic oils, such as certain esters of carboxylic acids and alcohols, distinct from the ester defined according to the invention, from polyalphaolefins (PAO), and from polyalkylene glycol (PAG) obtained by polymerization or copolymerization of alkylene oxides comprising 2 to 8 carbon atoms, in particular 2 to 4 carbon atoms.

[0092] PAOs used as base oils are for example obtained from monomers comprising 4 to 32 carbon atoms, for example from octene or decene.

[0093] 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.

[0094] For example, the PAOs implemented within the framework of the invention, having a kinematic viscosity, measured at 100 °C according to the ASTM D445 standard, ranging from 1.5 to 8 mm2 / s are sold commercially by Ineos under the brands Durasyn® 162, Durasyn® 164, Durasyn® 166 and Durasyn® 168.

[0095] Advantageously, the additional base oil or oils are chosen from polyalphaolefins (PAO).

[0096] It is for a person skilled in the art to adjust the content of the additional base oil(s) present in the composition according to the invention.

[0097] In particular, a composition according to the invention may comprise from 5 to 95% by mass, preferably from 50 to 95% by mass, preferably still from 60 to 90% by mass, of one or more base oils different from the diesters according to the invention, relative to the total mass of said composition. Additives

[0098] A cooling and / or lubrication composition according to the invention may further comprise one or more additives known to those skilled in the art in the field of lubrication and in particular in the field of lubrication and / or cooling of propulsion systems of electric or hybrid vehicles.

[0099] The additives, which can be incorporated into a composition according to the invention, can be chosen from friction modifier 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.

[0100] Preferably, a cooling and / or lubrication composition according to the invention may further comprise one or more additives selected from antioxidants, antifoams, pour point improvers and anti-corrosion agents.

[0101] The addition of one or more additives selected from among anti-wear additives, friction modifiers, detergents, extreme-pressure additives, and dispersants may also prove advantageous in the context of implementing the cooling composition according to the invention as a multifunctional fluid, for example, for cooling the battery and / or power electronics, and for lubrication parts of the propulsion system, for example the transmission, in an electric or hybrid vehicle.

[0102] It is understood that the nature and quantity of additives used are chosen so as not to affect the properties of the cooling and / or lubrication composition conferred by the diester according to the invention.

[0103] These additives can be introduced individually and / or in the form of a mixture similar to those already available for sale for commercial lubricant formulations for vehicle engines, of performance level as defined by ACEA (European Automobile Manufacturers' Association) and / or API (American Petroleum Institute), well known to those skilled in the art.

[0104] The said additive(s) may be present in the cooling and / or lubrication composition according to the invention in a content 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.

[0105] A cooling and / or lubrication composition implemented according to the invention may thus include at least one antioxidant additive.

[0106] The invention thus relates, according to another of its aspects, to a cooling and / or lubrication composition, in particular suitable for cooling a propulsion system, in particular the engine or geared motor, the battery and / or the power electronics of an electric or hybrid vehicle, said composition comprising (i) at least one diester as defined above, and (ii) at least one antioxidant additive.

[0107] 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.

[0108] Antioxidant additives act, in particular, as radical inhibitors or hydroperoxide scavengers. Commonly used antioxidant additives include phenolic antioxidants, amine antioxidants, and phosphosulfur antioxidants. Some of these antioxidant additives, for example, phosphosulfur antioxidants, may generate ash. Phenolic antioxidant additives may be ash-free or in the form of neutral or basic metal salts. Antioxidant additives may be selected, in particular, from sterically hindered phenols, sterically hindered phenol esters, and sterically hindered phenols comprising a thioether bridge, diphenylamines, diphenylamines substituted with at least one Ci-Ci2 alkyl group, N,N'-dialkylaryl diamines, and mixtures thereof.

[0109] Preferably according to the invention, sterically hindered phenols are chosen from compounds comprising a phenol group in which at least one vicinal carbon of the carbon bearing the alcohol function is substituted by at least one CrCio alkyl group, preferably a Ci-C6 alkyl group, preferably a C4 alkyl group, preferably by the tert-butyl group.

[0110] Amino compounds are another class of antioxidant additives that can be used, possibly in combination with phenolic antioxidant additives. Examples of amine compounds are aromatic amines, for example aromatic amines of formula NR4R5R6 in which R4 represents an aliphatic or aromatic group, possibly substituted, R5 represents an aromatic group, possibly substituted, R6 represents a hydrogen atom, an alkyl group, an aryl group or a group of formula R7S(O)ZR8 in which R7 represents an alkylene or alkenylene group, R8 represents an alkyl, alkenyl or aryl group and z represents 0, 1 or 2.

[0111] Sulfurized alkyl phenols or their alkali and alkaline earth metal salts can also be used as antioxidant additives.

[0112] Another class of antioxidant additives is that of copper compounds, for example copper thio- or dithio-phosphates, copper salts of carboxylic acids, dithiocarbamates, sulfonates, phenates, copper acetylacetonates. Copper I and II salts, succinic acid or succinic anhydride salts can also be used.

[0113] Advantageously, a cooling and / or lubrication composition includes at least one ash-free antioxidant additive.

[0114] The said additive(s) can be implemented, 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.

[0115] A cooling and / or lubrication composition according to the invention may include at least one anti-wear and / or extreme-pressure additive.

[0116] Anti-wear additives and extreme pressure additives protect surfaces in friction by forming a protective film adsorbed on these surfaces.

[0117] There is a wide variety of anti-wear additives. Preferably, anti-wear additives are chosen from among phosphosulfur additives such as metal alkylthiophosphates, in particular zinc alkylthiophosphates, and more specifically zinc dialkyldithiophosphates or ZnDTP. Preferred compounds have the formula Zn((SP(S)(OQ2)(OQ3))2, in which Q2 and Q3 are identical or different, independently represent an alkyl group, preferably an alkyl group comprising from 1 to 18 carbon atoms.

[0118] Amine phosphates are also anti-wear additives that can be used in a composition according to the invention. However, the phosphorus supplied by these additives can act as a poison for the catalytic converters of automobiles because these additives generate ash. These effects can be minimized by partially substituting the amine phosphates with additives that do not supply phosphorus, such as, for example, polysulfides, in particular sulfur olefins.

[0119] A cooling and / or lubrication 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.

[0120] A cooling and / or lubrication composition according to the invention may also include at least one additive improving the viscosity index (VI).

[0121] Viscosity index improvers, in particular viscosity index improving polymers, make it possible to guarantee good cold resistance and minimal viscosity at high temperature.

[0122] Examples of viscosity index improving polymers include polymer esters, homopolymers or copolymers, hydrogenated or non-hydrogenated, of styrene, butadiene and isoprene, homopolymers or copolymers of olefin, such as ethylene or propylene, polyacrylates and polymethacrylates (PMA), preferably homopolymers or copolymers of olefin, such as ethylene or propylene.

[0123] In particular, a lubricating 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 lubricating composition.

[0124] A cooling and / or lubrication composition according to the invention may further comprise an antifoaming agent.

[0125] The antifoaming agent can be chosen from silicones.

[0126] A cooling and / or lubrication 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.

[0127] A cooling and / or lubrication composition according to the invention may include at least one friction-modifying additive.

[0128] The friction-modifying additive can be selected from a compound containing metallic elements and an ash-free compound. Examples of compounds containing metallic elements include transition metal complexes such as Mo, Sb, Sn, Fe, Cu, Zn, whose ligands 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 selected from fatty acid and polyol monoesters, alkoxylated amines, alkoxylated fatty amines, fatty epoxides, borate fatty epoxides; fatty amines or glycerol esters of fatty acids. According to the invention, the fatty compounds comprise at least one hydrocarbon group comprising 10 to 24 carbon atoms.

[0129] A cooling and / or lubrication 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 modifier additive, relative to the total mass of the composition.

[0130] Advantageously, a cooling and / or lubrication composition is free of friction-modifying additives, particularly for use in cooling the battery section.

[0131] A cooling and / or lubrication composition according to the invention may include at least one detergent additive.

[0132] Detergent additives generally make it possible to reduce the formation of deposits on the surface of metal parts by dissolving secondary oxidation and combustion products.

[0133] Detergent additives usable in a cooling and / or lubricating composition are generally known to those skilled in the art. Detergent additives may be anionic compounds comprising a lipophilic hydrocarbon group and a hydrophilic head. The associated cation may be a metallic cation of an alkali or alkaline earth metal.

[0134] Detergent additives are preferably selected from alkali metal or alkaline earth metal salts of carboxylic acids, sulfonates, salicylates, naphthenates, and phenate salts. The alkali and alkaline earth metals are preferably calcium, magnesium, sodium, or barium.

[0135] These metallic salts generally comprise the metal in stoichiometric quantities or in excess, i.e., in a quantity greater than the stoichiometric quantity. These are then referred to as over-basic detergent additives; the excess metal giving the detergent additive its over-basic character is then generally in the form of a metallic salt insoluble in oil, for example a carbonate, a hydroxide, an oxalate, an acetate, a glutamate, preferably a carbonate.

[0136] A cooling and / or lubrication composition may, for example, comprise 2 to 4% by mass of detergent additive, relative to the total mass of the composition.

[0137] A cooling and / or lubrication composition may also include at least one pour point lowering additive.

[0138] By slowing down the formation of paraffin crystals, pour point lowering additives generally improve the cold behavior of the composition. Examples of pour point lowering additives include alkyl polymethacrylates, polyacrylates, polyarylamides, polyalkylphenols, polyalkylnaphthalenes, and alkylated polystyrenes.

[0139] Also, a cooling and / or lubrication composition may include at least one dispersing agent.

[0140] The dispersing agent can be chosen from Mannich bases, succinimides and their derivatives. A cooling composition may, for example, comprise from 0.2 to 10% mass of dispersing agent, relative to the total mass of the composition.

[0141] According to a particular embodiment, a cooling and / or lubrication composition implemented according to the invention comprises, or is formed from (i) at least one diester according to the invention and (ii) at least one additive selected from antioxidants, antifoaming agents, pour point lowering additives, anti-corrosion agents, anti-wear and / or extreme-pressure additives, friction modifiers, detergents, dispersing agents and mixtures thereof, preferably from antioxidants, pour point lowering additives, antifoaming agents and anti-corrosion agents.

[0142] Advantageously, a cooling and / or lubrication composition implemented according to the invention is formed (i) of at least one diester corresponding to formula (I) as defined above and (ii) of at least one antioxidant additive.

[0143] According to a particular embodiment, a cooling and / or lubrication composition implemented according to the invention comprises, or is made up of: - at least 5% by mass, preferably at least 10% by mass, preferably at least 30% by mass, preferably at least 50% by mass, more preferably at least 70% by mass, or even at least 90% by mass, of diester(s) meeting the formula (I); - possibly from 0.01 to 20% by mass, preferably from 0.05 to 15% by mass, preferably still from 0.1 to 10% by mass, even more preferably from 0.5 to 7% by mass, or even from 1 to 5% by mass, of one or more additives chosen from among friction modifiers, anti-wear additives, extreme pressure additives, detergents, antioxidants, viscosity index (VI) improvers, additives pour point depressants (PPDs), dispersants, antifoaming agents, thickeners, corrosion inhibitors, copper passivating agents, and mixtures thereof; and - possibly from 5 to 94% by mass, preferably from 10 to 94% by mass, preferably from 15 to 90% by mass of separate base oil(s) from the diester according to the invention,

[0144] the contents being expressed in relation to the total mass of said composition.

[0145] According to a particular embodiment, a cooling and / or lubrication composition implemented according to the invention comprises, or is made up of: - from 5 to 95% by mass, preferably from 5 to 50% by mass, preferably still 10 to 40% by mass, of said or said diesters corresponding to formula (i); - from 5 to 95% by mass, preferably from 50 to 95% by mass, preferably from 60 to 90% by mass, of one or more base oils different from said diesters; - possibly from 0.01 to 20% by mass, preferably from 0.05 to 15% by mass, preferably still from 0.1 to 10% by mass, even more preferably from 0.5 to 7% by mass, or even from 1 to 5% by mass, of one or more additives chosen from among friction modifiers, anti-wear additives, extreme pressure additives, detergents, antioxidants, viscosity index (VI) improvers, pour point depressants (PPD) additives, dispersants, antifoaming agents, thickeners, corrosion inhibitors, copper passivating agents, and mixtures thereof,

[0146] the contents being expressed in relation to the total mass of said composition.

[0147] According to a particular embodiment, a cooling and / or lubrication composition implemented according to the invention comprises, or is made up of: - from 5 to 95% by mass, preferably from 10 to 90% by mass, preferably still from 20 to 80% by mass, even more preferably from 30 to 70% by mass, or even from 40 to 60% by mass, of diester(s) meeting the formula (i); - possibly from 5 to 95% by mass, preferably from 10 to 90% by mass, preferably still from 20 to 80% by mass, even more preferably from 30 to 70% by mass, or even from 40 to 60% by mass of one or more base oils different from said diesters; - possibly from 0.01 to 20% by mass, preferably from 0.05 to 15% by mass, preferably still from 0.1 to 10% by mass, even more preferably from 0.5 to 7% by mass, or even from 1 to 5% by mass of a or several additives distinct from the biodiesel and distinct from the base oil(s), including friction modifiers, anti-wear additives, extreme pressure additives, detergents, antioxidants, viscosity index (VI) improvers, pour point depressants (PPD) additives, dispersants, antifoaming agents, thickeners, corrosion inhibitors, copper passivating agents, and mixtures thereof,

[0148] the contents being expressed in relation to the total mass of said composition.

[0149] A cooling and / or lubrication composition implemented according to the invention advantageously has a kinematic viscosity, measured at 100°C according to ASTM D445, ranging from 1 to 6 mm2 / s, preferably from 1 to 4 mm2 / s.

[0150] A cooling and / or lubrication composition implemented according to the invention advantageously has a kinematic viscosity, measured at 40°C according to ASTM D445, ranging from 2 to 20 mm2 / s, preferably from 3 to 18 mm2 / s. Preparation process

[0151] The diesters according to the invention can be prepared by synthetic methods known to those skilled in the art. These synthetic methods more particularly involve two esterification reactions, each esterification reaction being carried out between an alcohol function of the diol and the acid function of the monocarboxylic acid.

[0152] Of course, it is up to a person skilled in the art to adjust the synthesis conditions to obtain a diester according to the invention.

[0153] The invention also relates to a method for preparing the lubricating composition according to the invention, said method comprising:

[0154] a) an esterification step of each hydroxyl function of pentanediol using one or more monocarboxylic acids, identical or different, comprising a linear or branched hydrocarbon chain comprising 4 to 10 carbon atoms, said hydrocarbon chain optionally comprising one or more heteroatoms, such as a nitrogen or oxygen atom, in order to obtain one or more diesters,

[0155] b) optionally the mixture of the diester(s) from step a) with at least one base oil separate from the diester and / or at least one additive separate from the diester, said additive being selected from friction modifier 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.

[0156] According to one embodiment, the preparation process further comprises a preliminary step of preparing pentanediol, said preliminary step being preferably a reduction step of a keto-acid, preferably levulinic acid, said keto-acid preferably being derived from vegetable raw materials.

[0157] Thus, pentanediol, monocarboxylic acids, base oils and additives used in the preparation process according to the invention can each have one or more of the characteristics defined in the composition according to the invention. Application

[0158] As previously stated, a composition according to the invention can be implemented as a cooling and / or lubricating fluid for a propulsion system of an electric or hybrid vehicle.

[0159] As schematically represented in [Fig.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).

[0160] The electric motor typically comprises power electronics (11) connected to a stator (13) and a rotor (14). The stator includes coils, in particular copper coils, which are alternately energized by an electric current. This generates a rotating magnetic field. The rotor itself comprises coils, permanent magnets, or other magnetic materials, and is set in rotation by the rotating magnetic field.

[0161] The power electronics (11), the stator (13) and the rotor (14) of a propulsion system (1) are complex components that generate a significant amount of heat during motor operation. Therefore, it is essential to ensure cooling of the electric motor and the power electronics.

[0162] 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 rotational speed at the output of the electric motor and to adapt the speed transmitted to the wheels, thus allowing the speed of the vehicle to be controlled at the same time.

[0163] 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 in direct contact with the battery.

[0164] As suitable batteries for the propulsion systems of an electric or hybrid vehicle, Li-ion batteries or nickel-cadmium batteries can be mentioned in particular.

[0165] The invention further relates, according to another aspect, to a method for cooling at least one part of a propulsion system of an electric or hybrid vehicle, in particular the battery, comprising at least one step of bringing at least said part, in particular said battery, into contact, for example of a lithium-ion or nickel-cadmium battery, with a composition comprising at least one diester according to the invention, as defined above.

[0166] Bringing the cooling composition according to the invention into contact with the battery can consist of immersing or semi-immersing the battery in said composition or injecting said composition onto the surface of the battery.

[0167] By "immersion," it is meant that the entire battery is surrounded by the cooling composition according to the invention. By "semi-immersion," it is meant that only a portion of the battery is in contact with said composition.

[0168] Cooling can be achieved by any method known to those skilled in the art. The battery can be immersed or semi-immersed, static or circulating, in said composition.

[0169] 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 battery.

[0170] Advantageously, the composition is injected by jet under sufficiently high pressure into the areas of the propulsion system to be cooled. Advantageously, the shear resulting from this injection reduces the viscosity of the fluid at the injection site, relative to the kinematic viscosity at rest, and thus further increases the cooling potential of the composition.

[0171] In addition, oil circulation systems commonly used in electric motors can be employed, as for example described in document WO 2015 / 116496.

[0172] A composition according to the invention can further be implemented 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.

[0173] The cooling composition according to the invention has, in particular, electrical insulation properties that are particularly satisfactory for use in electric or hybrid vehicles.

[0174] It is possible to take advantage, in addition to the cooling properties of a composition according to the invention, of its lubrication properties.

[0175] 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 the bearings located between the rotor and the stator of an electric motor, or the transmission, in particular the reducer, in an electric or hybrid vehicle.

[0176] In the case of such an application, a cooling composition according to the invention advantageously further comprises one or more additives selected from among anti-wear additives, friction modifiers, detergents, dispersants, extreme-pressure additives, and mixtures thereof.

[0177] The invention will now be described by means of the following examples, given of course by way of illustration and not limitation of the invention. Examples Example 1: Preparation of the tested compounds

[0178] The following compounds were prepared: - Diester A: diester formed from 1,4-pentanediol and two heptanoic acids, - Diester B: diester formed from 1,4-pentanediol and two isovaleric acids, - Diester C: diester formed from 1,4-pentanediol and two levulinic acids, - Diester D: diester formed from 1,4-pentanediol and a bio-based cut of C8-C10 acids (octanoic acids and decanoic acids), - monoester comprising 20 carbon atoms, formed from a monocarboxylic acid comprising a saturated hydrocarbon chain of 3 to 14 carbon atoms; and a monoalcohol comprising a saturated hydrocarbon chain of 3 to 14 carbon atoms.

[0179] The diesters and the monoester were prepared according to known methods of ester preparation.

[0180] The compositions tested in the following examples comprise 100% of each ester (diester or monoester) defined in this example 1. Example 2: Viscosity Measurement

[0181] The kinematic viscosity at 100°C (KV100) and the kinematic viscosity at 40°C (KV40) were determined according to ASTM D445.

[0182] Viscosities are shown in Table 2.

[0183] [Tables2] KV100 (mm2 / s) KV40 (mm2 / s) Diester A 1.96 5.81 Diester B 1.50 4.32 Diester C 3.43 16.95 Diester D 2.55 8.24 Monoester 1.8 5.2

[0184] The diesters implemented according to the invention have a viscosity of less than 4 mm% at 100°C.

[0185] The diesters according to the invention also exhibit good cold-weather properties. Indeed, diester A according to the invention has a Brookfield viscosity at -40°C of 3010 mPa·s. The Brookfield viscosity was measured according to ASTM D 2983, 2022. Example 3: Measurement of friction coefficients

[0186] Tribological properties can be evaluated by a test on a ball-on-disc (also called ball-on-plate) rotary tribometer of the linear reciprocating tribometer type. This test makes it possible, in particular, to evaluate the performance of lubricants in terms of friction under mixed / limit conditions according to the applied load, pressure, or speed conditions.

[0187] The coefficient of friction of the tested lubricating compositions is determined at 140°C by using a hardened steel ball of approximately 2 cm in diameter, for example 1.905 cm in diameter, on a hardened steel surface.

[0188] The tribometer can be a device for setting a steel ball and a steel plate in relative motion in order to determine the coefficients of friction for a given lubricant composition, while varying various properties such as speed, load, and temperature. The hardened steel plate is AISI 52100 with a mirror finish, and the ball is also AISI 52100 made of hardened steel.

[0189] The applied load is 25 N and the drive speed varies from 10 mm / s to 2500 mm / s. The coefficient of friction is determined in particular at a rotational speed of 10 mm / s. The coefficient is determined at a slide-to-roll ratio (SRR) of 20% to 100%.

[0190] Approximately 50 ml of the tested lubricating composition were introduced into the device. The ball is engaged face-to-plane, said ball and said plan being actuated independently so as to create a mixed rolling / sliding contact.

[0191] The coefficient of friction is measured and recorded via a force sensor.

[0192] The results with a training velocity of 225 mm2 / s are shown in Table 3.

[0193] The tested lubricating compositions comprise 100% of each ester defined in Example 1.

[0194] [Tables3] 20% 40% 60% 80% 100% Diester A 0.0414 0.0634 0.0612 0.0548 0.548 Diester C 0.0472 0.0482 0.0482 0.0487 0.0488 Diester D 0.0591 0.0669 0.0662 0.0658 0.0666 Monoester 0.0681 0.0702 0.0699 0.0693 0.705

[0195] These results show that the diesters implemented according to the invention have very low coefficients of friction, in particular a lower coefficient of friction than the monoester. Example 4: Measuring the minimum pour point

[0196] The minimum pour point is measured according to ASTM D7346.

[0197] The values ​​are shown in Table 4.

[0198] [Tables4] Minimum pour point (°C) Diester A -95 Diester B -81 Diester C -45 Monoester -34

[0199] The results in Table 5 show that the diesters used in the lubricating composition according to the invention have a low pour point, in particular lower than the monoester. Example 5: Measurement of thermal conductivity

[0200] The thermal conductivity of the compounds described in Example 1 was determined according to ASTM D7896-19 at various temperatures.

[0201] The results are shown in Table 5.

[0202] [Tables5] Thermal conductivity (mW.m'.K') 50°C 90°C 130°C Diester A 145.0 136.4 127.6 Diester C 157.7 151.9 144.4 Diester D 142.4 134.8 126.3 Monoester 141.1 132.2 123.4

[0203] These results show that the diesters defined in the invention have good thermal properties, which allows their use as a cooling fluid. Example 6: Measurement of traction coefficients

[0204] The coefficient of traction (COT) was measured using the MTM tribometer from PCS instrument. It allows for the evaluation of lubricant performance in terms of friction under mixed / hydrodynamic conditions. This test consists of setting a steel ball and a steel plate in relative motion at different speeds, allowing the determination of the %SSR (Slide-to-Roll Ratio), which corresponds to the sliding speed / drive speed. This test aims to reproduce limiting lubrication conditions.

[0205] The measurement conditions were 25 N load, a disk speed of 1.4 m / s for an estimated temperature of 140 °C and an SRR of 60%, 80% and 100%.

[0206] The lower the coefficient of traction for a lubricating composition, the more the friction between the metal parts is reduced, thus resulting in a greater gain in terms of fuel economy.

[0207] The results obtained are shown in Table 6.

[0208] [Tableauxô] 60%SRR 80%SRR 100%SRR Diester A 0.0136 0.0144 0.0153 Diester C 0.0107 0.0124 0.014 Monoester 0.016 0.0182 0.0198

[0209] These results show that the diesters defined in the invention have a good coefficient of traction and in particular a better coefficient of traction than the monoester. Example 7

[0210] The mini flash point is measured according to ASTM D93Ac (open vessel Cleaveland method).

[0211] The values ​​are shown in Table 7.

[0212] [Tables7] Mini flash point (°C) Diester A 169.3 Diester C 207.5 Diester D 206

[0213] The diesters according to the invention exhibit a very good flash point.

Claims

Demands

1. Use, for cooling and / or lubricating a propulsion system of an electric or hybrid vehicle, of a composition comprising: - at least one diester formed between: • a pentanediol, and • two monocarboxylic acids, identical or different, comprising a linear or branched hydrocarbon chain having from 4 to 10 carbon atoms, said hydrocarbon chain optionally comprising one or more heteroatoms, such as a nitrogen or oxygen atom, and - optionally at least one base oil distinct from the diester and / or at least one additive distinct from the diester, said additive being selected from friction modifiers, anti-wear additives, extreme pressure additives, detergents, antioxidants, viscosity index (VI) improvers, pour point depressants (PPD) additives, dispersants, antifoaming agents, thickeners, corrosion inhibitors,copper passivating agents, and mixtures thereof, said diester having a kinematic viscosity at 100°C ranging from 1 to 6 mm² / s.

2. Use according to claim 1, wherein pentanediol is 1,4-pentanediol.

3. Use according to claim 1 or 2, wherein the pentanediol is obtained from the reduction of a keto acid, preferably levulinic acid, said keto acid preferably being obtained from vegetable raw materials.

4. Use according to any one of claims 1 to 3, wherein said diester has a kinematic viscosity at 100°C ranging from 1 to 4 mm2 / s.

5. Use according to any one of claims 1 to 4, wherein said monocarboxylic acids, identical or different, comprise a linear alkyl chain having from 4 to 10 carbon atoms, preferably from 5 to 9 carbon atoms, or even from 5 to 8 carbon atoms, the said alkyl chain possibly comprising one or more heteroatoms, for example one or more oxygen atoms.

6. Use according to any one of claims 1 to 5, wherein said diester(s) is / are selected from: - a diester formed from 1,4-pentanediol and two heptanoic acids, - a diester formed from 1,4-pentanediol and two pentanoic acids, - a diester formed from 1,4-pentanediol and two isovaleric acids, - a diester formed from 1,4-pentanediol and two levulinic acids, - a diester formed from 1,4-pentanediol and two nonanoic acids, - a diester formed from 1,4-pentanediol and two octanoic acids, - a diester formed from 1,4-pentanediol and two decanoic acids, - a diester formed from 1,4-pentanediol and of octanoic acid and decanoic acid, and mixtures thereof.

7. Use according to any one of claims 1 to 6, wherein the composition comprises:

8. - from 5 to 95% by mass, preferably from 10 to 90% by mass, preferably still from 20 to 80% by mass, even more preferably from 30 to 70% by mass, or even from 40 to 60% by mass of said diester(s), - from 1 to 95% by mass, preferably from 10 to 90% by mass, preferably even more from 20 to 80% by mass, even more preferably from 30 to 70% by mass, or even from 40 to 60% by mass of one or more base oils different from said diesters, - possibly from 0.01 to 20% by mass, preferably from 0.05 to 15% by mass, preferably still from 0.1 to 10% by mass, even more preferably from 0.5 to 7% by mass, or even from 1 to 5% by mass of one or more additives distinct from the diester and distinct from the base oil(s), relative to the total mass of the composition. Use according to any one of claims 1 to 6, wherein the composition comprises: - at least 5% by mass, preferably at least 10% by mass, preferably at least 30% by mass, preferably at least 50% by mass, more preferably at least 70% by mass, or even at least 90% by mass, of one or more diesters; - from 0.01 to 20% by mass, preferably from 0.05 to 15% by mass, preferably still from 0.1 to 10% by mass, even more preferably from 0.5 to 7% by mass, or even from 1 to 5% by mass, of one or more additives chosen from among friction modifiers, anti-wear additives, extreme pressure additives, detergents, antioxidants, viscosity index (VI) improvers, pour point depressants (PPD) additives, dispersants, antifoaming agents, thickeners, corrosion inhibitors, copper passivating agents, and mixtures thereof; and - optionally from 5 to 94% by mass, preferably from 10 to 94% by mass, preferably from 15 to 90% by mass of separate base oil(s) from said diester, relative to the total mass of the composition.

9. Use according to any one of claims 1 to 8, wherein the diester has a biologically sourced carbon content of at least 60% by weight, preferably at least 75% by weight, more preferably at least 90% by weight, or even at least 95% by weight, relative to the total weight of carbon atoms in said ester.

10. Use according to any one of claims 1 to 6 or 9, wherein the composition comprises at least 5% by mass, preferably at least 10% by mass, preferably still at least 30% by mass, even more preferably at least 50% by mass, or even at least 70% by mass of said diester(s) or 100% by mass of said diester(s), relative to the total mass of the composition.

11. Use according to any one of claims 1 to 6 or 9, wherein the composition consists of one or more diesters and one or more base oils different from said diesters, preferably in a proportion such that the composition consists of: - 5 to 95% by mass, preferably 5 to 50% by mass, preferably a further 10 to 40% by mass, of the diester(s), and - 5 to 95% by mass, preferably 50 to 95% by mass, preferably 60 to 90% by mass, of one or more base oils different from the diesters, relative to the total mass of the composition.

12. Use according to any one of claims 1 to 11, for cooling the battery and / or power electronics of an electric or hybrid vehicle, in particular a lithium-ion or nickel-c odium battery.

13. Use according to any one of claims 1 to 12, for cooling and / or for protecting against thermal runaway a battery, preferably a lithium-ion battery.

14. Use according to any one of claims 1 to 13, wherein the vehicle is an electric vehicle.

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