FR3145568A1 - Use of a diester in a cooling and/or lubricating composition for an electric or hybrid vehicle - Google Patents

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, comprising a linear or branched hydrocarbon chain comprising 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 chosen from friction modifying additives, anti-wear additives, extreme pressure additives, detergents, antioxidants, viscosity index (VI) improvers, pour point depressant (PPD) additives, dispersants, anti-foaming agents, thickeners, corrosion inhibitors, copper passivators, and mixtures thereof. Figure for abstract: None

Description

Use of a diester in a cooling and/or lubricating composition for an electric or hybrid vehicle

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 engine or geared motor, the battery and/or the power electronics of an electric or hybrid vehicle. It aims in particular to propose a cooling composition compatible with its implementation at the level of an engine or geared motor, a battery and/or the power electronics.

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.

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 car companies.

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

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

Generally speaking, it is necessary to implement, in electric or hybrid vehicles, compositions to meet the lubrication and/or cooling constraints of the various parts of the propulsion system mentioned above.

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

Traditionally, it is known to cool electric motors with air or water, possibly combined with glycol. However, with the advent of increasingly smaller and more powerful motors, these cooling methods are no longer sufficient. In addition, the heat that a battery can generate, especially during rapid charging, cannot be extracted by the methods traditionally used.

Thus, alternative methods of cooling and lubricating propulsion systems, especially batteries, have recently been proposed.

In this respect, lubricating compositions have been proposed to ensure the dual function of lubrication and cooling. Lubricating compositions are conventionally composed of one or more base oils, to which are generally associated several additives dedicated to boosting the lubricating performance of the base oils, such as for example friction modifier additives.

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 from 2 to 8 carbon atoms.

The invention aims specifically to propose a new composition, suitable for its implementation for the cooling and/or lubrication of the propulsion systems of electric or hybrid vehicles, in particular for the cooling of the motor or the geared motor, the batteries and/or the power electronics, or in particular for the lubrication of the motor or the geared motor, or even of the reducer alone.

• au moins un diester formé entre :
  • un pentanediol, et
  • deux acides monocarboxyliques, identiques ou différents, comportant une chaîne hydrocarbonée linéaire ou ramifiée comportant de 4 à 10 atomes de carbone, ladite chaine hydrocarbonée comportant éventuellement un ou plusieurs hétéroatomes, tels qu’un atome d’azote ou d’oxygène, et
• éventuellement au moins une huile de base distincte du diester et/ou au moins un additif distinct du diester, ledit additif étant choisi parmi les additifs modificateurs de frottement, les additifs anti-usure, les additifs extrême pression, les détergents, les antioxydants, les améliorants de l’indice de viscosité (VI), les additifs abaisseurs du point d’écoulement (PPD), les dispersants, les agents anti-mousse, les épaississants, les inhibiteurs de corrosion, les agents passivant du cuivre, et leurs mélanges.

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 comprising 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 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 passivators, and mixtures thereof.

• le pentanediol est le 1,4-pentanediol, et/ou
• le pentanediol est issu de la réduction d’un céto-acide, de préférence de l’acide lévulinique, ledit céto-acide étant de préférence issu de matières premières végétales, et/ou
• ledit diester présente une viscosité cinématique à 100°C allant de 1 à 6 mm²/s, de préférence allant de 1 à 4 mm²/s, et/ou
• lesdits acides monocarboxyliques, identiques ou différents, comportent une chaîne alkyle linéaire comportant de 4 à 10 atomes de carbone, de préférence de 5 à 9 atomes de carbone, voire de 5 à 8 atomes de carbone, ladite chaîne alkyle comportant éventuellement un ou plusieurs hétéroatomes, par exemple un ou plusieurs atomes d’oxygène, et/ou
• ledit ou lesdits diester(s) est(sont) choisi(s) parmi :
  • un diester formé à partir de 1,4-pentanediol et de deux acides heptanoïques,
  • un diester formé à partir de 1,4-pentanediol et de deux acides pentanoïques,
  • un diester formé à partir de 1,4-pentanediol et de deux acides isovalériques,
  • un diester formé à partir de 1,4-pentanediol et de deux acides lévuliniques,
  • un diester formé à partir de 1,4-pentanediol et de deux acides nonanoïques,
  • un diester formé à partir de 1,4-pentanediol et de deux acides octanoïques,
  • un diester formé à partir de 1,4-pentanediol et de deux acides décanoïques,
  • un diester formé à partir de 1,4-pentanediol et d’un acide octanoïque et d’un acide décanoïque,

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 plant 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, identical or different, comprise a linear alkyl chain comprising from 4 to 10 carbon atoms, preferably from 5 to 9 carbon atoms, or even from 5 to 8 carbon atoms, said alkyl chain optionally comprising one or more heteroatoms, for example one or more oxygen atoms, and/or
• 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 an octanoic acid and a decanoic acid,

• la composition comprend par rapport à la masse totale de la composition :
  • de 5 à 95% massique, de préférence de 10 à 90% massique, de préférence encore de 20 à 80% massique, encore plus préférentiellement de 30 à 70% massique, voire de 40 à 60% massique dudit ou desdits diesters,
  • de 1 à 95% massique, de préférence de 10 à 90% massique, de préférence encore de 20 à 80% massique, encore plus préférentiellement de 30 à 70% massique, voire de 40 à 60% massique d’une ou plusieurs huiles de base différentes desdits diesters,
  • éventuellement de 0,01 à 20% massique, de préférence de 0,05 à 15% massique, de préférence encore de 0,1 à 10% massique, encore plus préférentiellement de 0,5 à 7% massique, voire de 1 à 5% massique d’un ou plusieurs additifs distincts du diester et distincts de(s) huile(s) de base, et/ou
• la composition comprend par rapport à la masse totale de la composition :
  • au moins 5% massique, de préférence au moins 10% massique, de préférence au moins 30% massique, de préférence au moins 50% massique, plus préférentiellement au moins 70% massique, voire au moins 90% massique, d’un ou plusieurs diesters ;
  • de 0,01 à 20% massique, de préférence de 0,05 à 15% massique, de préférence encore de 0,1 à 10% massique, encore plus préférentiellement de 0,5 à 7% massique, voire de 1 à 5% massique, d’un ou plusieurs additifs choisi(s) parmi les additifs modificateurs de frottement, les additifs anti-usure, les additifs extrême pression, les détergents, les antioxydants, les améliorants de l’indice de viscosité (VI), les additifs abaisseurs du point d’écoulement (PPD), les dispersants, les agents anti-mousse, les épaississants, les inhibiteurs de corrosion, les agents passivant du cuivre, et leurs mélanges ; et
  • éventuellement de 5 à 94% massique, de préférence de 10 à 94% massique, de préférence de 15 à 90% massique d’huile(s) de base distincte(s) dudit diester, et/ou
• le diester présente une teneur en carbone d’origine biologique d’au moins 60% en poids, de préférence d’au moins 75% en poids, de préférence encore d’au moins 90% en poids, voire d’au moins 95% en poids, par rapport au poids total des atomes de carbone dudit ester, et/ou
• la composition comprend au moins 5% massique, de préférence au moins 10% massique, de préférence encore au moins 30% massique, encore plus préférentiellement au moins 50% massique, voire au moins 70% massique dudit ou desdits diesters ou 100% massique dudit ou desdits diesters, par rapport à la masse totale de la composition, et/ou
• la composition consiste en un ou plusieurs diesters et en une ou plusieurs huiles de base différentes desdits diesters, de préférence en une proportion telle que la composition consiste en :
  • de 5 à 95% en masse, de préférence de 5 à 50% en masse, de préférence encore 10 à 40% en masse, du ou des diesters, et
  • de 5 à 95% en masse, de préférence de 50 à 95% en masse, de préférence de 60 à 90% en masse, d’une ou plusieurs huiles de base différentes des diesters,
  • par rapport à la masse totale de la composition.

and their mixtures, 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, more preferably 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, more preferably 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,
  • optionally from 0.01 to 20% by mass, preferably from 0.05 to 15% by mass, more preferably 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), 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, more preferably 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 friction modifier additives, anti-wear additives, extreme pressure additives, detergents, antioxidants, viscosity index (VI) improvers, pour point depressants (PPD), dispersants, anti-foaming agents, thickeners, corrosion inhibitors, copper passivators, 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 base oil(s) distinct from said diester, and/or
• the diester has a carbon content of biological origin 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 the carbon atoms of said ester, and/or
• the composition comprises at least 5% by mass, preferably at least 10% by mass, 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:
  • from 5 to 95% by mass, preferably from 5 to 50% by mass, more preferably 10 to 40% by mass, of the diester(s), 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 other than diesters,
  • relative to the total mass of the composition.

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.

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.

According to one embodiment, the vehicle is an electric vehicle.

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 for lubricating and/or for cooling elements of a propulsion system of an electric or hybrid vehicle, in particular an electric vehicle.

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 vehicle.

Furthermore, the diesters defined in the present invention exhibit excellent cold properties.

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

Finally, the diesters defined in the present invention have good thermal conductivity, demonstrating the cooling capabilities of a diester-based lubricating composition according to the invention.

In the remainder of the text, the expressions “between … and …”, “ranging from … to …” and “varying from … to …” are equivalent and are intended to mean that the limits are included, unless otherwise stated.

Unless otherwise indicated, the expression “comprising a” must be understood as “comprising at least one”.

Detailed description

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 from 4 to 10 carbon atoms, said hydrocarbon chain optionally comprising one or more heteroatoms, such as a nitrogen or oxygen atom.

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 from 4 to 10 carbon atoms, said hydrocarbon chain optionally comprising one or more heteroatoms, such as a nitrogen or oxygen atom.

• au moins un diester formé entre :

• un pentanediol, de préférence le 1,4-pentanediol, et
• deux acides monocarboxyliques, identiques ou différents, comportant une chaîne hydrocarbonée linéaire ou ramifiée comportant de 4 à 10 atomes de carbone, ladite chaine hydrocarbonée comportant éventuellement un ou plusieurs hétéroatomes, tels qu’un atome d’azote ou d’oxygène,

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 comprising from 4 to 10 carbon atoms, said hydrocarbon chain optionally comprising one or more heteroatoms, such as a nitrogen or oxygen atom,

said diester preferably having a carbon content of biological origin 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 the carbon atoms of said ester,

• éventuellement au moins un ingrédient choisi parmi les huiles de base distinctes du diester, les additifs distincts du diester, et leurs mélanges, lorsqu’il est présent ledit additif étant de préférence choisi parmi les additifs modificateurs de frottement, les additifs anti-usure, les additifs extrême pression, les détergents, les antioxydants, les améliorants de l’indice de viscosité (VI), les additifs abaisseurs du point d’écoulement (PPD), les dispersants, les agents anti-mousse, les épaississants, les inhibiteurs de corrosion, les agents passivant du cuivre, et leurs mélanges.

And

• optionally at least one ingredient selected from base oils other than diester, additives other than diester, and mixtures thereof, when present said additive preferably being selected from friction modifier additives, anti-wear additives, extreme pressure additives, detergents, antioxidants, viscosity index (VI) improvers, pour point depressants (PPD), dispersants, anti-foaming agents, thickeners, corrosion inhibitors, copper passivators, and mixtures thereof.

• un pentanediol, de préférence le 1,4-pentanediol, et
• deux acides monocarboxyliques, identiques ou différents, comportant une chaîne hydrocarbonée linéaire ou ramifiée comportant de 4 à 10 atomes de carbone.

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 containing from 4 to 10 carbon atoms.

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

• un diester formé entre le 1,4-pentanediol et deux acides A1,
• un diester formé entre le 1,4-pentanediol et deux acides A2,
• un diester formé entre le 1,4-pentanediol et deux acides A3,
• un diester formé entre le 1,4-pentanediol et un acide A1 et un acide A2,
• un diester formé entre le 1,4-pentanediol et un acide A1 et un acide A3,
• un diester formé entre le 1,4-pentanediol et un acide A2 et un acide A3.

For example, it is possible to react 1,4-pentanediol and three monocarboxylic acids A1, A2 and A3. Thus, according to this example, the mixture of diesters falling within the scope of the present invention is likely to comprise:

• a diester formed between 1,4-pentanediol and two A1 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 acid A1 and an acid A2,
• a diester formed between 1,4-pentanediol and an acid A1 and an acid A3,
• a diester formed between 1,4-pentanediol and an acid A2 and an acid A3.

Diester implemented according to the invention

As mentioned above, the diester(s) used according to the invention is (are) formed between a pentanediol and two monocarboxylic acids.

For the purposes of the present invention, the term “diester formed between a pentanediol and two monocarboxylic acids” means 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.

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

By "pentanediol" we mean a compound containing (exactly) two hydroxyl functions (-OH) and five carbon atoms.

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.

For the purposes of the invention, the term “hydrocarbon chain” is intended to denote 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 consisting of carbon and hydrogen atoms.

The diol used according to the invention may be commercially available or synthesized according to any method known to those skilled in the art.

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

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

Preferably, levulinic acid is derived from plant raw materials, such as cellulose or sugar.

Thus, preferably, the diol used in the invention comes from plant raw materials, such as cellulose or sugar.

Preferably, the diol used according to the invention comprises a carbon content of biological origin 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 diol.

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

The diester used according to the invention is obtained from two identical or different monocarboxylic acids.

By "monocarboxylic acid" is meant a compound having a single carboxyl function (-COOH).

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

According to one embodiment, the monocarboxylic acids, identical or different, comprise a linear hydrocarbon chain comprising from 5 to 10 carbon atoms, more preferably from 5 to 9 carbon atoms or even from 5 to 8 carbon atoms.

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

The monocarboxylic acids used according to the invention may be commercially available or synthesized according to any method known to those skilled in the art.

Preferably, the monocarboxylic acids used according to the invention comprise a carbon content of biological origin 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.

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

By way of example, the diesters according to the invention may be formed from a pentanediol, preferably 1,4-pentanediol and a biosourced cut comprising several monocarboxylic acids comprising from 4 to 10 carbon atoms, for example a biosourced cut comprising monocarboxylic acids comprising 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.

Preferably, the diester used according to the invention is saturated.

For the purposes of the invention, the term “saturated diester” means a diester comprising saturated hydrocarbon chains. Thus, preferably, the monocarboxylic acids used according to the invention each comprise a saturated hydrocarbon chain, preferably, said hydrocarbon chain is made up of carbon and hydrogen atoms.

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.

For the purposes of the invention, the term “branched diester” means 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.

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

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

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

It is understood that the definitions given above for carboxylic acid and alcohol may be combined, where possible, to define other particular embodiments.

A diester used according to the invention may more particularly correspond to formula (I):

• R¹représente une chaîne hydrocarbonée, linéaire ou ramifiée, saturée ou insaturée, de préférence saturée, présentant de 3 à 9 atomes de carbone, de préférence de 4 à 8 atomes de carbone, de préférence de 5 à 7 atomes de carbone, ladite chaîne hydrocarbonée étant éventuellement interrompue par un ou plusieurs hétéroatomes, tels que des atomes d’oxygène, de préférence la chaine hydrocarbonée est constituée d’atomes de carbone et d’hydrogène ; et
• R²représente une chaîne hydrocarbonée, linéaire ou ramifiée, saturée ou insaturée, de préférence saturée, présentant de 3 à 9 atomes de carbone, de préférence de 4 à 8 atomes de carbone, de préférence de 5 à 7 atomes de carbone, ladite chaîne hydrocarbonée étant éventuellement interrompue par un ou plusieurs hétéroatomes, tels que des atomes d’oxygène, de préférence la chaine hydrocarbonée est constituée d’atomes de carbone et d’hydrogène.

in which:

• R ¹ represents a linear or branched, saturated or unsaturated, preferably saturated, hydrocarbon chain 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 is made up of carbon and hydrogen atoms; and
• R ² represents a linear or branched, saturated or unsaturated, preferably saturated, hydrocarbon chain 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 is made up of carbon and hydrogen atoms.

In the diester of formula (I), R ¹ and R ² may be the same or different.

According to one embodiment, R¹and R² are chosen from alkyls comprising from 3 to 9 carbon atoms, linear or branched, optionally comprising a ketone functional group (of type >=O). An example of a monocarboxylic acid which can result in a diester of formula (I) in which R¹and/or R² include(s) a carboxyl functional group is levulinic acid.

• un diester formé à partir de 1,4-pentanediol et de deux acides heptanoïques,
• un diester formé à partir de 1,4-pentanediol et de deux acides pentanoïques,
• un diester formé à partir de 1,4-pentanediol et de deux acides isovalériques,
• un diester formé à partir de 1,4-pentanediol et de deux acides lévuliniques,
• un diester formé à partir de 1,4-pentanediol et de deux acides nonanoïques,
• un diester formé à partir de 1,4-pentanediol et de deux acides octanoïques,
• un diester formé à partir de 1,4-pentanediol et de deux acides décanoïques,
• un diester formé à partir de 1,4-pentanediol et d’un mélange d’acides comprenant un acide octanoïque et un acide décanoïque,

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 including an octanoic acid and a decanoic acid,

and their mixtures.

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.

Preferably, the diester used according to the invention comprises a carbon content of biological origin 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 diester.

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

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 the ASTM D93Ac standard (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.

The diester or the mixture of diesters according to the invention may 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.

• de 5 à 95% en masse, de préférence de 5 à 50% en masse, de préférence encore 10 à 40% en masse, du ou des diesters selon l’invention, et
• de 5 à 95% en masse, de préférence de 50 à 95% en masse, de préférence de 60 à 90% en masse, d’une ou plusieurs huiles de base différentes des diesters selon l’invention,

The diester(s) according to the invention may be used with one or more additional base oils (also called co-bases). According to this embodiment, preferably, the composition will comprise:

• from 5 to 95% by mass, preferably from 5 to 50% by mass, more preferably 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,

relative to the total mass of the diester(s) and the base oils other than the diesters.

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.

According to a particular embodiment, a lubricating composition according to the invention may 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.

• de 5 à 95% en masse, de préférence de 5 à 50% en masse, de préférence encore 10 à 40% en masse, du ou des diesters selon l’invention, et
• de 5 à 95% en masse, de préférence de 50 à 95% en masse, de préférence de 60 à 90% en masse, d’une ou plusieurs huiles de base différentes des diesters selon l’invention,

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 of ancillary 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, more preferably 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,

relative to the total mass of the composition.

This embodiment is particularly advantageous when the composition is used for cooling, as a cooling fluid.

Annex base oil(s) (co-base(s))

The lubricating composition according to the invention may comprise, in addition to one or more diesters according to the invention, one or more base oils distinct from the diesters according to the invention, called “additional base oil”.

Said base oil(s), optionally present in the lubricating composition according to the invention, are chosen appropriately, with regard to their compatibility with said diester(s) used according to the invention.

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

Preferably, the base oil or mixture of additional base oils, used in the lubricating composition according to the invention, may have a kinematic viscosity, measured at 100°C according to the ASTM D445 standard, 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.

Base oils may be chosen from oils of mineral or synthetic origin belonging to groups I to V according to the classes defined in the API classification (or their equivalents according to the ATIEL classification) and presented in table 1 below or their mixtures.

Saturated content Sulfur content Viscosity index (VI) Group I (Mineral oils) < 90% > 0.03% 80 ≤VI < 120 Group II (Hydrocracked oils) ≥90% ≤0.03% 80 ≤VI < 120 Group III (Hydrocracked or hydroisomerized oils) ≥90% ≤0.03% ≥120 Group IV Polyalphaolefins (PAO) Group V Esters and other bases not included in groups I to IV

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

Mixtures of synthetic and mineral oils, which can be bio-sourced, can also be used.

The base oils may also be chosen from synthetic oils, such as certain esters of carboxylic acids and alcohols, other than the ester defined according to the invention, from polyalphaolefins (PAOs), and from polyalkylene glycols (PAGs) obtained by polymerization or copolymerization of alkylene oxides comprising from 2 to 8 carbon atoms, in particular from 2 to 4 carbon atoms.

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

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.

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

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

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

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

Additives

A cooling and/or lubricating 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.

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

Preferably, a cooling and/or lubricating composition according to the invention may further comprise one or more additives chosen from antioxidants, anti-foams, pour point improvers and anti-corrosion agents.

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

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 lubricating composition conferred by the diester according to the invention.

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

Said additive(s) may be present in the cooling and/or lubricating composition according to the invention in a content of less than or equal to 10% by mass, in particular less than or equal to 5% by mass, and more particularly ranging from 0.01 to 3% by mass, relative to the total mass of said composition.

A cooling and/or lubricating composition used according to the invention can thus comprise at least one antioxidant additive.

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

The antioxidant additive generally makes it possible to delay the degradation of the composition in service. This degradation can notably result in the formation of deposits, the presence of sludge or an increase in the viscosity of the composition.

Antioxidant additives act in particular as radical inhibitors or hydroperoxide destroyers. Among the commonly used antioxidant additives, mention may be made of phenolic antioxidant additives, amine antioxidant additives, and phosphosulfur antioxidant additives. Some of these antioxidant additives, for example phosphosulfur antioxidant additives, may be ash-generating. Phenolic antioxidant additives may be ash-free or in the form of neutral or basic metal salts. Antioxidant additives may in particular be chosen from sterically hindered phenols, sterically hindered phenol esters and sterically hindered phenols comprising a thioether bridge, diphenylamines, diphenylamines substituted by at least one C ₁ -C ₁₂ alkyl group, N,N'-dialkyl-aryl-diamines and mixtures thereof.

Preferably according to the invention, the sterically hindered phenols are chosen from compounds comprising a phenol group of which at least one vicinal carbon of the carbon carrying the alcohol function is substituted by at least one C ₁ - C ₁₀ alkyl group, preferably a C ₁ - C ₆ alkyl group, preferably a C ₄ alkyl group, preferably by the tert-butyl group.

Amino compounds are another class of antioxidant additives that can be used, possibly in combination with phenolic antioxidant additives. Examples of amino compounds are aromatic amines, for example aromatic amines of the formula NR⁴R⁵R⁶in which R⁴represents an aliphatic group or an aromatic group, optionally substituted, R⁵represents an aromatic group, optionally substituted, R⁶ represents a hydrogen atom, an alkyl group, an aryl group or a group of formula R⁷S(O)_zR⁸in which R⁷represents an alkylene group or an alkenylene group, R⁸represents an alkyl group, an alkenyl group or an aryl group and z represents 0, 1 or 2.

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

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

Advantageously, a cooling and/or lubricating composition comprises at least one ash-free antioxidant additive.

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

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

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

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

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

A cooling and/or lubricating composition may comprise from 0.01 to 6% by mass, preferably from 0.05 to 4% by mass, more preferably from 0.1 to 2% by mass of anti-wear additives and extreme pressure additives, by mass relative to the total mass of the composition.

A cooling and/or lubricating composition according to the invention may also comprise at least one additive improving the viscosity index (VI).

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

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

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.

A cooling and/or lubricating composition according to the invention may further comprise an antifoaming agent.

The antifoaming agent can be chosen from silicones.

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

A cooling and/or lubricating composition according to the invention may comprise at least one friction modifying additive.

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

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

Advantageously, a cooling and/or lubricating composition is free of friction modifying additive, in particular for use in cooling the battery part.

A cooling and/or lubricating composition according to the invention may comprise at least one detergent additive.

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

Detergent additives that can be used in a cooling and/or lubricating composition are generally known to those skilled in the art. The detergent additives may be anionic compounds comprising a lipophilic hydrocarbon group and a hydrophilic head. The associated cation may be a metal cation of an alkali or alkaline-earth metal.

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

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

A cooling and/or lubricating composition may for example comprise from 2 to 4% by weight of detergent additive, relative to the total weight of the composition.

A cooling and/or lubricating composition may also include at least one pour point depressant additive.

By slowing the formation of paraffin crystals, pour point depressant additives generally improve the cold behavior of the composition. Examples of pour point depressant additives include polyalkyl methacrylates, polyacrylates, polyarylamides, polyalkylphenols, polyalkylnaphthalenes, alkylated polystyrenes.

Also, a cooling and/or lubricating composition may comprise at least one dispersing agent.

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

According to a particular embodiment, a cooling and/or lubricating 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 chosen from antioxidants, anti-foaming 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, anti-foaming agents and anti-corrosion agents.

Advantageously, a cooling and/or lubricating composition used according to the invention is formed (i) from at least one diester corresponding to formula (I) as defined above and (ii) from at least one antioxidant additive.

• au moins 5% massique, de préférence au moins 10% massique, de préférence au moins 30% massique, de préférence au moins 50% massique, plus préférentiellement au moins 70% massique, voire au moins 90% massique, de diester(s) répondant à la formule (I) ;
• éventuellement de 0,01 à 20% massique, de préférence de 0,05 à 15% massique, de préférence encore de 0,1 à 10% massique, encore plus préférentiellement de 0,5 à 7% massique, voire de 1 à 5% massique, d’un ou plusieurs additifs choisi(s) parmi les additifs modificateurs de frottement, les additifs anti-usure, les additifs extrême pression, les détergents, les antioxydants, les améliorants de l’indice de viscosité (VI), les additifs abaisseurs du point d’écoulement (PPD), les dispersants, les agents anti-mousse, les épaississants, les inhibiteurs de corrosion, les agents passivant du cuivre, et leurs mélanges ; et
• éventuellement de 5 à 94% massique, de préférence de 10 à 94% massique, de préférence de 15 à 90% massique d’huile(s) de base distincte(s) du diester selon l’invention,

According to a particular embodiment, a cooling and/or lubricating composition implemented according to the invention comprises, or even consists 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) corresponding to formula (I);
• optionally from 0.01 to 20% by mass, preferably from 0.05 to 15% by mass, more preferably 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 friction modifier additives, anti-wear additives, extreme pressure additives, detergents, antioxidants, viscosity index (VI) improvers, pour point depressants (PPD), dispersants, anti-foaming agents, thickeners, corrosion inhibitors, copper passivators, 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 base oil(s) distinct from the diester according to the invention,

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

• de 5 à 95% en masse, de préférence de 5 à 50% en masse, de préférence encore 10 à 40% en masse, dudit ou desdits diesters répondant à la formule (I) ;
• de 5 à 95% en masse, de préférence de 50 à 95% en masse, de préférence de 60 à 90% en masse, d’une ou plusieurs huiles de base différentes desdits diesters ;
• éventuellement de 0,01 à 20% massique, de préférence de 0,05 à 15% massique, de préférence encore de 0,1 à 10% massique, encore plus préférentiellement de 0,5 à 7% massique, voire de 1 à 5% massique, d’un ou plusieurs additifs choisi(s) parmi les additifs modificateurs de frottement, les additifs anti-usure, les additifs extrême pression, les détergents, les antioxydants, les améliorants de l’indice de viscosité (VI), les additifs abaisseurs du point d’écoulement (PPD), les dispersants, les agents anti-mousse, les épaississants, les inhibiteurs de corrosion, les agents passivant du cuivre, et leurs mélanges,

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

• from 5 to 95% by mass, preferably from 5 to 50% by mass, more preferably 10 to 40% by mass, of said diester(s) 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;
• optionally from 0.01 to 20% by mass, preferably from 0.05 to 15% by mass, more preferably 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 friction modifying additives, anti-wear additives, extreme pressure additives, detergents, antioxidants, viscosity index (VI) improvers, pour point depressants (PPD), dispersants, anti-foaming agents, thickeners, corrosion inhibitors, copper passivators, and mixtures thereof,

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

• de 5 à 95% massique, de préférence de 10 à 90% massique, de préférence encore de 20 à 80% massique, encore plus préférentiellement de 30 à 70% massique, voire de 40 à 60% massique, de diester(s) répondant à la formule (I) ;
• éventuellement de 5 à 95% massique, de préférence de 10 à 90% massique, de préférence encore de 20 à 80% massique, encore plus préférentiellement de 30 à 70% massique, voire de 40 à 60% massique d’une ou plusieurs huiles de base différentes desdits diesters ;
• éventuellement de 0,01 à 20% massique, de préférence de 0,05 à 15% massique, de préférence encore de 0,1 à 10% massique, encore plus préférentiellement de 0,5 à 7% massique, voire de 1 à 5% massique d’un ou plusieurs additifs distincts du diester et distincts de(s) huile(s) de base, parmi les additifs modificateurs de frottement, les additifs anti-usure, les additifs extrême pression, les détergents, les antioxydants, les améliorants de l’indice de viscosité (VI), les additifs abaisseurs du point d’écoulement (PPD), les dispersants, les agents anti-mousse, les épaississants, les inhibiteurs de corrosion, les agents passivant du cuivre, et leurs mélanges,

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

• from 5 to 95% by mass, preferably from 10 to 90% by mass, more preferably 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) corresponding to formula (I);
• optionally from 5 to 95% by mass, preferably from 10 to 90% by mass, more preferably 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;
• optionally from 0.01 to 20% by mass, preferably from 0.05 to 15% by mass, more preferably 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), among 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 passivators, and mixtures thereof,

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

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

A cooling and/or lubricating composition used according to the invention advantageously has a kinematic viscosity, measured at 40°C according to standard ASTM D445, ranging from 2 to 20 mm²/s, preferably from 3 to 18 mm²/s.

Preparation process

The diesters according to the invention can be prepared according to synthesis methods known to those skilled in the art. These synthesis methods more particularly implement two esterification reactions, each esterification reaction being implemented between an alcohol function of the diol and the acid function of the monocarboxylic acid.

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

The invention also relates to a process for preparing the lubricating composition according to the invention, said process comprising:

a) a step of esterification of each hydroxyl function of pentanediol using one or more monocarboxylic acids, identical or different, comprising a linear or branched hydrocarbon chain comprising from 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,

b) optionally mixing the diester(s) from step a) with at least one base oil distinct from the diester and/or at least one additive distinct from the diester, said additive being chosen from friction modifying additives, anti-wear additives, extreme pressure additives, detergents, antioxidants, viscosity index (VI) improvers, pour point depressant (PPD) additives, dispersants, anti-foaming agents, thickeners, corrosion inhibitors, copper passivators, and mixtures thereof.

According to one embodiment, the preparation method further comprises a preliminary step of preparing pentanediol, said preliminary step preferably being a step of reducing a keto acid, preferably levulinic acid, said keto acid preferably being derived from plant raw materials.

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

Application

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

As schematically represented in , the propulsion system of an electric or hybrid vehicle, comprises in particular the electric motor part (1), an electric battery (2) and a transmission, and in particular a speed reducer (3).

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

The power electronics (11), stator (13) and rotor (14) of a propulsion system (1) are parts with a complex structure and generate a large amount of heat during engine operation. It is therefore imperative to ensure cooling of the electric motor and the power electronics.

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

Advantageously, a composition according to the invention can be used to cool the battery of an electric or hybrid vehicle. In particular, according to this embodiment, it is intended to be placed in direct contact with the battery.

As batteries suitable for the propulsion systems of an electric or hybrid vehicle, we can cite in particular Li-ion batteries or nickel-cadmium batteries.

The invention also relates, according to another of its aspects, 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, for example a lithium-ion or nickel-cadmium battery, into contact with a composition comprising at least one diester according to the invention, as defined above.

Bringing the cooling composition according to the invention into contact with the battery may consist of immersion or semi-immersion of the battery in said composition or even injection of said composition onto the surface of the battery.

By “immersion” is meant that the entire battery is surrounded by the cooling composition according to the invention. By “semi-immersion” is meant that only a portion of the battery is in contact with said composition.

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

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.

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

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

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

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

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

Thus, a composition according to the invention can simultaneously be used to lubricate the various parts of a propulsion system of an electric or hybrid vehicle, in particular bearings located between the rotor and the stator of an electric motor, or even the transmission, in particular the reducer, in an electric or hybrid vehicle.

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

The invention will now be described by means of the following examples, given of course as illustrations and not as limitations of the invention.

Examples Example 1: Preparation of the test compounds

• Diester A : diester formé à partir de 1,4-pentanediol et de deux acides heptanoïques,
• Diester B : diester formé à partir de 1,4-pentanediol et de deux acides isovalériques,
• Diester C : diester formé à partir de 1,4-pentanediol et de deux acides lévuliniques,
• Diester D : diester formé à partir de 1,4-pentanediol et d’une coupe biosourcée d’acides en C8-C10 (acides octanoïques et acides décanoïques),
• monoester comportant 20 atomes de carbone, formé à partir d’un acide monocarboxylique comportant une chaîne hydrocarbonée saturée de 3 à 14 atomes de carbone ; et un monoalcool comportant une chaîne hydrocarbonée saturée de 3 à 14 atomes de carbone.

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 biosourced cut of C8-C10 acids (octanoic acids and decanoic acids),
• monoester having 20 carbon atoms, formed from a monocarboxylic acid having a saturated hydrocarbon chain of 3 to 14 carbon atoms; and a monoalcohol having a saturated hydrocarbon chain of 3 to 14 carbon atoms.

The diesters and monoester were prepared according to known methods of ester preparation.

The compositions tested in the following examples comprise 100% of each ester (diester or monoester) defined in this example 1.

Example 2: Viscosity measurement

Kinematic viscosity at 100°C (KV100) and kinematic viscosity at 40°C (KV40) were determined according to ASTM D445.

Viscosities are shown in Table 2.

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

The diesters used according to the invention have a viscosity of less than 4 mm²/s at 100°C.

The diesters according to the invention also exhibit good cold properties. Indeed, the diester A according to the invention exhibits a Brookfield viscosity at -40°C of 3010 mPa.s. The Brookfield viscosity was measured according to ASTM D 2983, 2022.

Example 3: Measuring friction coefficients

Tribological properties can be assessed by a test on a rotating ball-disc tribometer (also called a ball-plate) of the Linear Reciprocating Tribometer type. This test is used in particular to assess the performance of lubricants in terms of friction in mixed/limit regime according to the load, pressure or speed conditions applied.

The coefficient of friction of the lubricating compositions tested 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 plane.

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

The applied load is 25 N respectively and the drive speed varies from 10 mm/s to 2500 mm/s. The friction coefficient is determined in particular at a rotation speed of 10 mm/s. The coefficient is determined at a sliding speed/drive speed ratio ("Slide-to-Roll Ratio" or %SRR) of 20% to 100%.

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

The coefficient of friction is measured and recorded using a force sensor.

The results with a drive speed of 225 mm²/s are shown in Table 3.

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

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

These results show that the diesters used according to the invention have very low coefficients of friction, in particular a lower coefficient of friction than the monoester.

Example 4: Measuring the mini pour point

The mini pour point is measured according to ASTM D7346.

The values are shown in Table 4.

Mini pour point (°C) Diester A -95 Diester B -81 Diester C -45 Monoester -34

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: Measuring thermal conductivity

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

The results are shown in Table 5.

Thermal conductivity (mW.m ^{- 1} .K ^-1 ) 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

These results show that the diesters defined in the invention have good thermal properties, which allows their use as a cooling fluid.

Example 6: Measurements of traction coefficients

The coefficient of traction (COT) was measured using the MTM tribometer from PCS instrument. It is used to evaluate the performance of lubricants in terms of friction in mixed/hydrodynamic conditions. This test consists of putting a steel ball and a steel plane in relative motion, at different speeds, to define the %SSR (Slide-to-Roll Ratio) which corresponds to the sliding speed/drive speed. This test aims to reproduce limit lubrication conditions.

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%.

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

The results obtained are shown in Table 6.

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

These results show that the diesters defined in the invention have a good traction coefficient and in particular a better traction coefficient than the monoester.

Example 7

The mini flash point is measured according to ASTM D93Ac (Cleaveland open cup method).

The values are shown in Table 7.

Mini flash point (°C) Diester A 169.3 Diester C 207.5 Diester D 206

The diesters according to the invention have a very good flash point.

Claims (14)

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 comprising 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 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 passivators, and mixtures thereof.

Use according to claim 1, wherein the pentanediol is 1,4-pentanediol. Use according to claim 1 or 2, wherein the pentanediol is derived from the reduction of a keto acid, preferably levulinic acid, said keto acid preferably being derived from plant raw materials. Use according to any one of claims 1 to 3, in which said diester has a kinematic viscosity at 100°C ranging from 1 to 6 mm²/s, preferably ranging from 1 to 4 mm²/s. Use according to any one of claims 1 to 4, in which said monocarboxylic acids, identical or different, comprise a linear alkyl chain comprising from 4 to 10 carbon atoms, preferably from 5 to 9 carbon atoms, or even from 5 to 8 carbon atoms, said alkyl chain optionally comprising one or more heteroatoms, for example one or more oxygen atoms. Use according to any one of claims 1 to 5, in which 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 an octanoic acid and a decanoic acid,

and their mixtures. Use according to any one of claims 1 to 6, in which the composition comprises:

• from 5 to 95% by mass, preferably from 10 to 90% by mass, more preferably 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, more preferably 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,
• optionally from 0.01 to 20% by mass, preferably from 0.05 to 15% by mass, more preferably 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, in which 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, more preferably 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 friction modifier additives, anti-wear additives, extreme pressure additives, detergents, antioxidants, viscosity index (VI) improvers, pour point depressants (PPD), dispersants, anti-foaming agents, thickeners, corrosion inhibitors, copper passivators, 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 base oil(s) distinct from said diester,

relative to the total mass of the composition. Use according to any one of claims 1 to 8, in which the diester has a carbon content of biological origin 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 the carbon atoms of said ester. Use according to any one of claims 1 to 6 or 9, in which the composition comprises at least 5% by mass, preferably at least 10% by mass, 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. Use according to any one of claims 1 to 6 or 9, in which 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:

• from 5 to 95% by mass, preferably from 5 to 50% by mass, more preferably 10 to 40% by mass, of the diester(s), 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 other than diesters,

relative to the total mass of the composition. Use according to any one of claims 1 to 11, for cooling the battery and/or the power electronics of an electric or hybrid vehicle, in particular a lithium-ion or nickel-cadmium battery. Use according to any one of claims 1 to 12, for cooling and/or protecting a battery, preferably a lithium-ion battery, against thermal runaway. Use according to any one of claims 1 to 13, wherein the vehicle is an electric vehicle.