Use of anti-wear additive for increasing thermal conductivity of cooling fluid for electric vehicle

Abstract

The invention relates to the use of at least one anti-wear additive for increasing the thermal conductivity of a fluid containing at least one base oil.

Description

Technical Field

[0001] The present invention relates to the field of lubricating compositions for electric vehicles. More specifically, the present invention relates to the field of lubricating and cooling compositions for electric vehicles, more specifically, to the field of cooling batteries of electric vehicles. Background Art

[0002] The development of international standards to reduce CO2 emissions and lower energy consumption has prompted car manufacturers to come up with alternative solutions to the internal combustion engine.

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

[0004] Generally, in vehicles, it is necessary to use lubricating compositions, also called "lubricating fluids", the main purpose of which is to reduce the friction between the different parts of the vehicle propulsion system, in particular the friction between the moving metal parts in the electric motors. In addition, such lubricating compositions effectively prevent premature wear and even damage to these parts, in particular their surfaces.

[0005] Electric motors generate heat during operation. If the heat generated is greater than what is normally dissipated to the environment, the engine needs to be cooled. Typically, one or more of the heat generating components of the engine and / or the heat sensitive components of the engine are cooled to prevent dangerous temperatures from being reached.

[0006] Cooling can be done by direct cooling or indirect cooling. Due to the continuous increase in the power density of electric motors, it is necessary to develop and improve the direct cooling mode of electric motors, in which the lubricating fluid of the transmission components will be further used to cool the high-temperature parts of the electric motor. An example is the Tesla Model S vehicle, in which the reducer lubricant is also circulated through the hollow rotor of the electric motor to cool the stator coil head by a large amount of injection oil.

[0007] To this end, lubricating compositions are generally composed of one or more base oils, usually combined with a variety of additives designed to enhance the lubricating properties of the base oils (eg, friction modifier additives).

[0008] For economy and ease of implementation, a composition that simultaneously meets the lubrication and cooling requirements of an electric vehicle propulsion system (engine, battery, etc.) would be advantageous.Unfortunately, at first glance, these two properties, lubrication and cooling, impose opposing constraints.

[0009] One type of property that is particularly useful for lubricating compositions for electric vehicle propulsion systems includes having good anti-wear properties, which are systematically required to be met as part of manufacturer specifications.

[0010] Furthermore, lubricating compositions of this type must facilitate cooling of the propulsion system of the electric vehicle.

[0011] It is therefore a subject of the present invention to provide a single fluid (single lubricating composition) that can be used in all components of an electric vehicle propulsion system. Summary of the invention

[0012] More precisely, the invention relates to the use of at least one antiwear additive for increasing the thermal conductivity of a fluid comprising at least one base oil.

[0013] According to the present invention, the antiwear additive is selected from phosphated antiwear additives, phosphosulfurized antiwear additives, phosphoaminated antiwear additives, sulfurized antiwear additives, borated antiwear additives and mixtures thereof.

[0014] According to one embodiment, the antiwear additive is used to improve the heat transfer properties of the fluid.

[0015] According to one embodiment, the fluid is used to cool a battery of an electric vehicle.

[0016] According to one embodiment, the anti-wear additive is used to prepare a single fluid, which is used to lubricate and cool the propulsion system of an electric vehicle. Thus, according to this embodiment, a single fluid (the same fluid) circulates throughout the cooling and lubrication systems of the electric vehicle propulsion system.

[0017] Preferably, the antiwear additive is selected from phosphated antiwear additives, phosphosulfurized antiwear additives, phosphoaminated antiwear additives and mixtures thereof, preferably selected from phosphated antiwear additives.

[0018] Preferably, the antiwear additive is a phosphite polymer, preferably corresponding to formula (I):

[0019]

[0020] in,

[0021] -R 1 , R 2 , R 3 and R 4 Each of which can be independently selected from C1-C20 alkyl, C3-C22 alkenyl, C6-C40 cycloalkyl, C7-C40 cycloalkenyl, C1-20 methoxyalkyl glycol ether and Y-OH part;

[0022] -Y is selected from C2-C40 alkylene, C2-C40 alkyl lactone moiety, -R 7 -N(R 8 )-R 9 Group, where R7 , R 8 and R 9 are independently selected from hydrogen, C1-C20 alkyl, C3-C22 alkenyl, C6-C40 cycloalkyl, C7-C40 cycloalkenyl, C1-20 methoxyalkyl glycol ether moiety,

[0023] -m is an integer from 2 to 100,

[0024] -n is an integer from 1 to 1000.

[0025] According to one embodiment, the weight average molecular weight of the phosphite polymer corresponding to formula (I) is preferably less than 30000 g / mol, preferably in the range of 5000 g / mol to 20000 g / mol.

[0026] According to one embodiment, the antiwear additive represents 0.01 to 10% by weight of the total weight of the fluid.

[0027] According to one embodiment, the antiwear additive comprises from 5 ppm to 9150 ppm by weight of phosphorus, preferably from 5 ppm to 4500 ppm by weight of phosphorus, relative to the total weight of the fluid.

[0028] According to one embodiment, the fluid comprises at least 70% by weight, preferably at least 80% by weight, more preferably at least 85% by weight of base oil relative to the total weight of the fluid.

[0029] According to one embodiment, the fluid comprises, relative to the total weight of the fluid:

[0030] - 70% to 99.99% by weight of one or more base oils, and

[0031] - 0.01 to 10% by weight of an antiwear additive, preferably selected from phosphated antiwear additives, preferably selected from phosphite polymers,

[0032] - Optionally, 1 to 30% by weight of one or more functional additives, preferably selected from viscosity index improvers, antioxidant additives, defoaming additives, dispersants, detergents, viscosity improvers and mixtures thereof.

[0033] The fluid used according to the invention has the advantage that it can be easily used for lubricating components of the propulsion system of an electric vehicle and for cooling components of the propulsion system of an electric vehicle.

[0034] Unless otherwise stated, quantities in products are expressed by weight and are relative to the total weight of the product. DETAILED DESCRIPTION

[0035] The present invention relates to the use of at least one antiwear additive:

[0036] - to increase the thermal conductivity of a fluid comprising at least one base oil, and / or

[0037] - for improving the heat transfer properties of a fluid comprising at least one base oil, and / or

[0038] - in a fluid comprising at least one base oil, for cooling a battery of an electric vehicle.

[0039] An "electric vehicle" as defined herein refers to a vehicle that includes an electric motor as the sole propulsion means, as distinguished from a hybrid vehicle that includes an internal combustion engine and an electric motor as a combined propulsion means.

[0040] The term "propulsion system" as defined herein refers to a system comprising the mechanical components required for the propulsion of a vehicle. In the context of an electric vehicle, the propulsion system therefore more specifically comprises the rotor-stator assembly of the electric motor or power electronics system (dedicated to speed regulation), a transmission (also called a reducer) and a battery.

[0041] The thermal conductivity can be determined according to standard ASTM D7896-19. Within the framework of the present invention, it is preferably determined at 30°C.

[0042] Anti-wear additives

[0043] An antiwear additive used in a lubricating composition is an additive known to have wear reducing properties when added to a base oil.

[0044] According to the present invention, the antiwear additive is selected from the group consisting of phosphated antiwear additives, phosphosulfurized antiwear additives, phosphoaminated antiwear additives, sulfurized antiwear additives, borated antiwear additives and mixtures thereof.

[0045] Preferably, the antiwear additive is selected from the group consisting of phosphated antiwear additives, phosphosulfurized antiwear additives, phosphoaminated antiwear additives and mixtures thereof.

[0046] As defined in the present invention, a "phosphated antiwear additive" refers to an antiwear additive that contains at least one phosphorus atom and contains neither sulfur nor nitrogen.

[0047] As defined in the present invention, a "sulphurized antiwear additive" is an antiwear additive that contains at least one sulphur atom and contains neither phosphorus nor nitrogen.

[0048] As defined in the present invention, a "phosphosulfurized antiwear additive" refers to an antiwear additive comprising at least one phosphorus atom and at least one sulfur atom and not comprising any nitrogen atom.

[0049] As defined in the present invention, a "phosphamidated antiwear additive" refers to an antiwear additive comprising at least one phosphorus atom and at least one nitrogen atom and not comprising any sulfur atom.

[0050] A "sulphurized antiwear additive" as defined in the present invention is an antiwear additive comprising at least one sulphur atom and not comprising any phosphorus atom nor any nitrogen atom.

[0051] As defined in the present invention, a "borated antiwear additive" refers to an antiwear additive that contains at least one boron atom and does not contain any phosphorus atom, does not contain a nitrogen atom, and does not contain a sulfur atom.

[0052] Antiwear additives, such as phosphated antiwear additives, phosphosulfurized antiwear additives, phosphoaminated antiwear additives, sulfurized antiwear additives and borated antiwear additives, are commercially available.

[0053] Among the phosphating antiwear additives, mention may be made of phosphates, phosphites and phosphonates. These terms refer to: phosphoric acid, phosphorous acid and phosphonic acid; monoesters, diesters and triesters of phosphoric acid, phosphorous acid and phosphonic acid, such as alkyl phosphates, alkyl phosphonates; and salts of phosphoric acid, phosphorous acid and phosphonic acid.

[0054] The phosphosulfurized antiwear additives used in the present invention, if any, may be (mono- or di-)thiophosphates and thiophosphites, which terms include thiophosphoric acids and thiophosphorous acids, esters of thiophosphoric acids and thiophosphorous acids, salts of thiophosphoric acids and thiophosphorous acids, and dithiophosphites and dithiophosphates.

[0055] As examples of phosphorus-cured antiwear additives, mention may be made of monobutyl thiophosphate, monooctyl thiophosphate, monolaur thiophosphate, dibutyl thiophosphate, dilaur thiophosphate, tributyl thiophosphate, trioctyl thiophosphate, triphenyl thiophosphate, monooctyl thiophosphite, trilaur thiophosphate, monolaur thiophosphite, monobutyl thiophosphite, dibutyl thiophosphite, dilaur thiophosphite, tributyl thiophosphite, trioctyl thiophosphite, triphenyl thiophosphite, trilaur thiophosphite and their salts.

[0056] Among the phosphosulfurized antiwear additives in salt form, mention may be made of metal salts of dithiophosphoric acids, such as zinc dithiophosphate, cobalt dithiophosphate or nickel dithiophosphate.

[0057] Among the sulfurized antiwear agents, mention may be made of sulfurized olefins, sulfurized esters, polysulfides (especially disulfides), thiocarbamates and dithiocarbamates and their salts.

[0058] Among the sulphurized antiwear agents in salt form, mention may be made of the type of metal salts of dithiocarbamic acids, for example zinc dithiocarbamate, cobalt dithiocarbamate or nickel dithiocarbamate.

[0059] Among the borated antiwear agents, mention may be made of borated esters, calcium borates and potassium borates.

[0060] According to one embodiment, the antiwear additive is chosen from phosphite polymers, preferably corresponding to formula (I):

[0061]

[0062] in,

[0063] -R 1 , R 2 , R 3 and R 4 Each of which can be independently selected from C1-C 20 Alkyl, C3-C 22 Alkenyl, C6-C 40 Cycloalkyl, C7-C 40 Cycloalkenyl, C 1-20 Methoxyalkyl glycol ether and Y-OH (used as terminal group) moiety;

[0064] -Y is selected from C2-C 40 Alkylene, C2-C 40 Alkyl lactone part, -R 7 -N(R 8 )-R 9 - group, where R 7 , R 8 and R 9 independently selected from hydrogen, C1-C 20 Alkyl, C3-C 22 Alkenyl, C6-C 40 Cycloalkyl, C7-C 40 Cycloalkenyl, C 1-20 Methoxyalkyl glycol ether moiety,

[0065] -m is an integer from 2 to 100,

[0066] -n is an integer from 1 to 1000.

[0067] For the purposes of the present invention, the term "alkyl" refers to a saturated, linear or branched non-cyclic hydrocarbon, optionally containing one or more heteroatoms, such as oxygen, nitrogen or sulfur atoms. Preferably, the alkyl group consists of carbon and hydrogen atoms.

[0068] As defined in the present invention, "alkenyl" refers to an unsaturated, linear or branched non-cyclic hydrocarbon, optionally containing one or more heteroatoms, such as oxygen, nitrogen or sulfur atoms. Preferably, the alkenyl group consists of carbon and hydrogen atoms.

[0069] "Cycloalkyl" as defined herein refers to a saturated monocyclic or polycyclic moiety optionally having one or more alkyl or alkenyl substituents, wherein the ring(s) themselves may be substituted with one or more heteroatoms (such as oxygen, nitrogen or sulfur atoms). Preferably, the cycloalkyl group is composed of carbon and hydrogen atoms.

[0070] "Cycloalkenyl" as defined herein refers to an unsaturated monocyclic or polycyclic moiety optionally having one or more alkyl or alkenyl substituents, wherein the ring(s) themselves may be substituted with one or more heteroatoms (such as oxygen, nitrogen or sulfur atoms). Preferably, the cycloalkenyl group consists of carbon and hydrogen atoms.

[0071] “C i -C j " moiety is a moiety comprising i to j carbon atoms.

[0072] According to a preferred embodiment, the Y group is selected from an alkylene group containing 2 to 20 carbon atoms, preferably 2 to 12 carbon atoms, or preferably 2 to 8 carbon atoms.

[0073] According to one embodiment, m ranges from 4 to 100.

[0074] According to one embodiment, the weight average molecular weight of the phosphite polymer corresponding to formula (I) is preferably less than 30000 g / mol, preferably in the range of 3000 g / mol to 20000 g / mol. The weight average molecular weight can be measured by size exclusion chromatography.

[0075] According to one embodiment, the number average molecular weight of the phosphite polymer corresponding to formula (I) is preferably less than 10000 g / mol, preferably in the range of 1000 g / mol to 5000 g / mol. The number average molecular weight can be measured by size exclusion chromatography.

[0076] According to one embodiment, it is preferred that the polydispersity index of the phosphite polymer corresponding to formula (I) is in the range of 1 to 5, preferably in the range of 2 to 4.

[0077] Preferably, the phosphite polymer corresponding to formula (I) contains less than 2% by weight, preferably less than 1% by weight or even less than 0.7% by weight of (alkyl)phenol moieties relative to the total weight of the phosphite polymer of formula (I).

[0078] Preferably, the phosphite polymer corresponding to formula (I) is completely free of aromatic moieties other than (alkyl)phenol moieties.

[0079] Generally, it is preferred that the phosphite polymer corresponding to formula (I) is in liquid form.

[0080] According to one embodiment, the phosphite polymer preferably corresponding to formula (I) has a phosphorus concentration ranging from 0.5% to 20% by weight, preferably from 1% to 10% by weight, relative to the total weight of the phosphite polymer.

[0081] The phosphite polymer that can be used in the present invention can be obtained according to the method described in document WO2011102861. More specifically, the polymer can be obtained according to the method described in paragraphs 27 to 32 of the document.

[0082] The synthesis of polymers of formula (I) generally involves a transesterification reaction in which triphenyl phosphite (or any other suitable alkyl or aryl phosphite) can be reacted with a saturated or unsaturated alcohol or a polyethylene or polypropylene glycol ether and a diol or diol polymer diol H(OY) m OH (wherein Y and m are as defined above) at a temperature between 20° C. and 250° C., preferably between 50° C. and 185° C. Examples of saturated or unsaturated alcohols include, but are not limited to, decyl glycol ether, isodecyl glycol ether, lauryl glycol ether, tridecyl glycol ether, isotridecyl glycol ether, tetradecyl glycol ether, pentadecyl glycol ether, hexadecyl glycol ether, stearyl glycol ether, isostearyl glycol ether, oleyl glycol ether, monohydroxy glycol ether.

[0083] Preferably, the fluid used according to the invention comprises from 0.01% to 10% by weight of antiwear additives, preferably from 0.01% to 5% by weight of antiwear additives, relative to the total weight of the fluid.

[0084] The amount of antiwear additive may be adjusted to obtain a phosphorus content in the fluid ranging from 5 ppm to 9150 ppm by weight. Preferably, the phosphorus concentration in the fluid used according to the invention ranges from 5 ppm to 4500 ppm by weight relative to the total weight of the fluid.

[0085] Base oil

[0086] The fluid used according to the invention comprises one or more base oils, preferably in a concentration of at least 70% by weight, preferably in the range of 70% to 99% by weight, further preferably in a concentration of 80% to 98% by weight, preferably in a concentration of 85% to 95% by weight, relative to the total weight of the fluid.

[0087] Such base oils can be selected from base oils commonly used in the lubricating oil field, such as synthetic or natural mineral oils, animal or vegetable oils, or mixtures thereof.

[0088] Mixtures of various base oils may be present, for example mixtures of two, three or four base oils.

[0089] The base oil of the fluid under consideration according to the invention may in particular be a mineral or synthetic oil belonging to groups I to V according to the categories defined by the API classification (or its equivalent according to the ATIEL classification), as shown in table 1 below, or mixtures thereof.

[0090] Table 1

[0091]

[0092] Mineral base oils include any type of base oil obtained by atmospheric and vacuum distillation of crude oil followed by refining operations such as solvent extraction, deasphalting, solvent dewaxing, hydrotreating, hydrocracking, hydroisomerization and hydrofinishing.

[0093] It is further possible to use mixtures of synthetic oils, which may be of biological origin, and mineral oils.

[0094] The use of different base oils for producing the composition used in the present invention is generally not limited, except that the composition must have properties suitable for use in electric or hybrid vehicle propulsion systems, in particular viscosity, viscosity index or oxidation resistance.

[0095] The base oil of the fluid used according to the invention may further be chosen from synthetic oils, such as certain carboxylic acid esters and alcohol esters, polyalphaolefins (PAO), and polyalkylene glycols (PAG) obtained by polymerization or copolymerization of alkylene oxides containing 2 to 8 carbon atoms, in particular 2 to 4 carbon atoms.

[0096] The PAO used as a base oil is obtained, for example, from a monomer comprising 4 to 32 carbon atoms, such as octene or decene. The weight average molecular weight of the PAO varies considerably. Preferably, the weight average molecular weight of the PAO is less than 600 Da. The weight average molecular weight of the PAO may further be in the range of 100 Da to 600 Da, in the range of 150 Da to 600 Da, or further in the range of 200 Da to 600 Da.

[0097] Advantageously, the base oil or oils of the fluid used according to the invention may be chosen from base oils of group II or group III.

[0098] According to an alternative embodiment, the base oil or base oils used according to the invention are chosen from polyalphaolefins (PAOs), polyalkylene glycols (PAGs), carboxylic acid esters and alcohol ethers.

[0099] Additional additives

[0100] Furthermore, the fluid used according to the invention may also contain all types of functional additives suitable for lubricants for electric vehicles, which are different from the antiwear additives defined in the context of the present invention.

[0101] Such additives known to those skilled in the art of electric vehicle lubrication may be selected from detergents, dispersants, antioxidants, pour point depressants, anti-foam additives, viscosity index improvers, and mixtures thereof.

[0102] Advantageously, the fluid used according to the invention comprises at least one functional additive selected from detergents, dispersants, antioxidants, pour point depressants, antifoam additives, viscosity index improvers and mixtures thereof.

[0103] Typically, when present, the additional functional additives (in total) comprise from 1% to 30% by weight, preferably from 1.5% to 25% by weight, preferably from 2% to 20% by weight, based on the total weight of the fluid.

[0104] Similar to additives already marketed for commercial lubricant formulations for vehicle engines, such additives may be introduced individually and / or as a mixture with performance levels defined by ACEA (European Automobile Manufacturers Association) and / or API (American Petroleum Institute), as is well known to those skilled in the art.

[0105] The fluid used according to the invention may contain at least one antioxidant additive.

[0106] Antioxidant additives generally retard the degradation of the composition in use. Such degradation can result significantly in the formation of deposits, the presence of sludge or an increase in the viscosity of the composition.

[0107] Antioxidant additives act in particular as free radical inhibitors or hydroperoxide destroyers. Commonly used antioxidant additives include phenolic antioxidants, amine antioxidant additives, and phosphosulfurized antioxidant additives. Some such antioxidant additives (such as phosphosulfurized antioxidant additives) can produce ash. Phenolic antioxidant additives may be ash-free, or may be in the form of neutral or alkaline metal salts. Antioxidant additives may be selected in particular from sterically hindered phenols, sterically hindered phenol esters, and sterically hindered phenols containing thioether bridges, diphenylamines, diphenylamines substituted with at least one C1-C12 alkyl group, N,N′-dialkylaryl diamines, and mixtures thereof.

[0108] Preferably, according to the present invention, the sterically hindered phenols are selected from compounds comprising a phenolic moiety in which at least one carbon adjacent to the carbon atom bearing the alcohol function is replaced by at least one C1-C 10Alkyl substituted, preferably C1-C6 alkyl substituted, preferably C4 alkyl substituted, preferably tert-butyl substituted.

[0109] Amine compounds are another class of antioxidant additives that may be used optionally in combination with phenolic antioxidant additives. Examples of amine compounds are aromatic amines, such as those of formula NR 10 R 11 R 12 Aromatic amines, where R 10 represents an aliphatic part or a possibly substituted aromatic part, R 11 represents the aromatic part which may be substituted, R 12 represents a hydrogen atom, an alkyl moiety, an aryl moiety or a group of formula R 13 S(O) z R 14 part, where R 13 represents an alkylene or alkenylene moiety, R 14 represents an alkyl moiety, an alkenyl moiety or an aryl moiety, and z is 0, 1 or 2.

[0110] Sulfuralkylphenols or alkali metal salts or alkaline earth metal salts thereof can further be used as antioxidant additives.

[0111] Another class of antioxidant additives are copper compounds, such as copper thiophosphates or dithiophosphates, copper salts and carboxylates, copper dithiocarbamates, copper sulfonates, copper phenates, copper acetylacetonate. Copper I and II salts, succinates or succinic anhydride salts can also be used.

[0112] The fluids used according to the invention may also contain any type of antioxidant known to those skilled in the art.

[0113] Advantageously, the fluid used according to the invention comprises at least one ashless antioxidant additive.

[0114] The fluid used according to the invention may comprise from 0.5% to 2% by weight of at least one antioxidant additive, relative to the total weight of the fluid.

[0115] The fluid used according to the invention may also contain at least one detergent additive.

[0116] Detergent additives generally reduce the formation of deposits on the surfaces of metal parts by dissolving oxidation and combustion byproducts.

[0117] Detergent additives that can be used for the fluids used in the present invention are generally known to those skilled in the art. Detergent additives can be anionic compounds comprising a long lipophilic hydrocarbon chain and a hydrophilic end. The associated cation can be a metal cation of an alkali metal or an alkaline earth metal.

[0118] The detergent additive is preferably selected from alkali metal or alkaline earth metal salts of carboxylic acids, sulfonates, salicylates, naphthenates and phenates. The alkali metal and alkaline earth metal are preferably calcium, magnesium, sodium or barium.

[0119] Such metal salts generally include a stoichiometric amount or an excess (i.e., greater than a stoichiometric amount) of the metal. These are then overbased detergents; the excess metal that gives the detergent additive an overbased character is generally in the form of an oil-insoluble metal salt, such as a carbonate, hydroxide, oxalate, acetate, glutamate, preferably a carbonate.

[0120] The fluid used according to the invention may comprise from 0.5% to 4% by weight of detergent additives relative to the total weight of the composition.

[0121] The fluid used according to the present invention may also contain at least one dispersant. Typically, the dispersant will be used to maintain in suspension and discharge insoluble solid contaminants consisting of oxidation byproducts formed when the fluid is used.

[0122] The dispersant may be selected from Mannich bases or succinimide compounds, such as polyisobutylene succinimide (PIBSI).

[0123] The fluid used according to the invention may contain, for example, from 0.2% to 10% by weight of dispersant, relative to the total weight of the fluid.

[0124] The fluid used according to the invention may also contain at least one antifoam additive.

[0125] The antifoam additive may be selected from polysiloxanes.

[0126] The fluid used according to the invention may comprise 0.01 to 2% by weight or 0.01 to 5% by weight, preferably 0.1 to 1.5% by weight or 0.1 to 2% by weight of antifoam additives, relative to the total weight of the fluid.

[0127] The fluid used according to the invention may also contain at least one pour point depressant (PPD) additive.

[0128] Pour point depressant additives generally improve the performance of the fluid in cold conditions by slowing down the formation of paraffin crystals. Examples of pour point depressant additives include alkyl polymethacrylates, polyacrylates, polyaramids, polyalkylphenols, polyalkylnaphthalenes, alkylpolystyrenes.

[0129] The fluid used according to the present invention may contain at least one additive that increases the viscosity index (VI improver). Examples of VI improvers include polymethacrylates, polyisobutylenes or fatty acid esters. When present, such additives may account for 1% to 25% by weight of the total weight of the fluid.

[0130] Regarding the formulation of such fluids, anti-wear additives may be added to the oil or base oil blend, followed by other possible supplemental additives.

[0131] Alternatively, the antiwear additive may be added to a pre-existing conventional lubricating formulation comprising, inter alia, one or more base oils and one or more supplementary additives.

[0132] Alternatively, when an antiwear additive is present, it may be combined with one or more additives and the resulting additive "package" added to the base oil or base oil blend.

[0133] Advantageously, the fluid according to the invention has a kinematic viscosity measured at 40° C. according to standard ASTM D445 in the range of 5 mm 2 / s to 300mm 2 / s, more particularly 10 mm 2 / s to 25mm 2 / s.

[0134] Advantageously, the fluid used according to the invention has a kinematic viscosity measured at 100° C. according to standard ASTM D445 in the range of 1 mm 2 / s to 20mm 2 / s, more particularly 2 mm 2 / s to 15mm 2 / s.

[0135] According to a particular embodiment, the fluid used according to the invention comprises or even consists of:

[0136] - a base oil or a mixture of base oils;

[0137] - one or more antiwear agents;

[0138] - optionally one or more additional additives selected from viscosity index improvers, detergents, dispersants, antioxidants, pour point depressants, antifoam additives and mixtures thereof.

[0139] According to a particular embodiment, the fluid according to the invention comprises or even consists of, relative to the total weight of the fluid:

[0140] - 70% to 99.99% by weight of one or more base oils, and

[0141] - 0.01 to 10% by weight of an antiwear additive, preferably selected from phosphated antiwear additives, preferably selected from phosphite polymers,

[0142] - Optionally, 1 to 30% by weight of one or more functional additives, preferably selected from viscosity index improvers, antioxidant additives, defoaming additives, dispersants, detergents, viscosity improvers and mixtures thereof.

[0143] According to a particular embodiment, the fluid according to the invention comprises or even consists of, relative to the total weight of the fluid:

[0144] - 70 to 99% by weight of one or more base oils, and

[0145] - 0.01 to 10% by weight of an antiwear additive, preferably selected from phosphated antiwear additives, preferably selected from phosphite polymers,

[0146] - Optionally, 1 to 30% by weight of one or more functional additives, preferably selected from viscosity index improvers, antioxidant additives, defoaming additives, dispersants, detergents, viscosity improvers and mixtures thereof.

[0147] According to a particular embodiment, the fluid used according to the invention comprises or even consists of, relative to the total weight of the fluid:

[0148] - at least 70% by weight, preferably from 70 to 99% by weight, of base oil;

[0149] - 0.05 to 10% by weight, in particular 0.1 to 7% by weight, more particularly 1 to 5% by weight, of a phosphite polymer corresponding to formula (I);

[0150] - Optionally, 1 to 20% by weight, preferably 1.5 to 10% by weight, more particularly 2 to 5% by weight, of one or more functional additives, preferably selected from viscosity index improvers, detergents, dispersants, antioxidants, pour point depressants, defoaming additives and mixtures thereof.

[0151] According to one embodiment, the fluid used according to the invention comprises from 5 ppm to 9150 ppm by weight of phosphorus, preferably from 5 ppm to 4500 ppm by weight of phosphorus, relative to the total weight of the fluid.

[0152] According to one embodiment, the fluid used according to the invention comprises from 5 to 4000 ppm by weight of sulphur, preferably from 7 to 1000 ppm by weight of sulphur or preferably from 10 to 800 ppm by weight of sulphur relative to the total weight of the fluid.

[0153] The invention further relates to the use of at least one antiwear additive for improving the heat transfer properties of a fluid comprising at least one base oil.

[0154] Preferably, the one or more antiwear additives have one or more characteristics defined in the present invention.

[0155] Preferably, the fluid has one or more of the properties defined in the present invention.

[0156] The invention further relates to the use of at least one antiwear additive in a fluid comprising at least one base oil for cooling a battery of an electric vehicle.

[0157] Preferably, the one or more antiwear additives have one or more characteristics defined in the present invention.

[0158] Preferably, the fluid has one or more of the properties defined in the present invention.

[0159] The invention further relates to the use of a fluid comprising at least one base oil and at least one antiwear additive for increasing the thermal conductivity of a fluid comprising at least one base oil and / or for increasing the heat transfer of a fluid and / or for cooling a battery of an electric vehicle.

[0160] Preferably, the one or more antiwear additives have one or more characteristics defined in the present invention.

[0161] Preferably, the fluid has one or more of the properties defined in the present invention.

[0162] According to another aspect of the present invention, the present invention further relates to a method for lubricating and cooling a propulsion system of an electric vehicle, the method comprising circulating a single fluid in a lubrication and cooling system of the entire propulsion system of the electric vehicle, the fluid comprising a base oil and at least one anti-wear additive.

[0163] Preferably, the one or more antiwear additives have one or more characteristics defined in the present invention.

[0164] Preferably, the fluid has one or more of the properties defined in the present invention.

[0165] Typically, the propulsion system of an electric vehicle includes an electric motor, a rotor-stator assembly of a power electronics system (dedicated to speed regulation), a transmission (also called a reducer), and a battery.

[0166] According to another aspect of the present invention, the present invention further relates to a method for improving the thermal conductivity of a fluid comprising at least one base oil, the method comprising the step of mixing at least one anti-wear additive as defined in the present invention with at least one base oil, preferably the anti-wear additive being selected from phosphating anti-wear additives, preferably being selected from phosphite polymers preferably corresponding to formula (I).

[0167] Preferably, the one or more antiwear additives have one or more characteristics defined in the present invention.

[0168] Preferably, the fluid has one or more of the properties defined in the present invention.

[0169] The present invention will now be described by way of the following examples which, of course, serve as illustrations of the present invention but are not intended to be limiting thereof.

[0170] Example

[0171] Example 1

[0172] In this embodiment, a phosphite polymer antiwear agent is used, for example. It is a phosphite polymer corresponding to the formula (I) described in the present invention. It contains 4.50% phosphorus and 0% sulfur by weight, a weight average molecular weight of about 10000 g / mol, a number average molecular weight of about 3000 g / mol, and can be obtained, for example, according to the method described in Example 2 of document WO 2011 / 102861.

[0173] In this example, a group III base oil is used. The base oil has a viscosity of 7.62 cSt at 40° C. measured according to standard ASTM D445.

[0174] In this example, fluid 1 contains 99% by weight of base oil and 1% by weight of anti-wear additives, and fluid 2 contains 95% by weight of base oil and 5% by weight of anti-wear additives.

[0175] Table 2 collates the thermal conductivity of the tested compositions at 30° C., 60° C. and 90° C. The thermal conductivity is measured according to standard ASTM D7896-19.

[0176] Table 2

[0177] Separate base oil Fluid 1 Fluid 2 Thermal conductivity at 30℃(mW.mK) 137 137.5 137.8 Thermal conductivity at 60℃(mW.mK) 129.3 130.3 130.5 Thermal conductivity at 90℃(mW.mK) 125 125.4 126.8

[0178] The results in Table 2 show that the antiwear additive increases the thermal conductivity of the lubricating composition at 30°C, 60°C and 90°C.

[0179] Example 2

[0180] The lubricating compositions were prepared by mixing the ingredients at a temperature of about 40° C. according to methods well known to those skilled in the art. The details of the lubricating compositions prepared and tested are given in Table 3 below.

[0181] The concentrations of elemental phosphorus and sulfur were calculated from the elemental concentrations in the compositions and are presented in Table 3 in ppm by weight.

[0182] Finally, the kinematic viscosity at 40° C. and 100° C. was determined by method ASTM D445 and is shown in Table 3.

[0183] Table 3

[0184]

[0185]

[0186] In the composition of Table 3:

[0187] - the base oil is a Group III base oil,

[0188] - the phosphite polymer is the same as the phosphite polymer used in Example 1,

[0189] The phosphated antiwear additive is tert-butylphenyl phosphate (not corresponding to formula (I)), which contains 8.10% by weight of phosphorus and 0% of sulfur and is marketed as an antiwear additive.

[0190] - the antioxidant is an alkylated diphenylamine antioxidant,

[0191] - The preservative is toluene triazine,

[0192] - The detergent is an overbased calcium sulfonate detergent,

[0193] -The additive package contains a pour point depressant and a defoamer.

[0194] The antiwear properties of the additives of the formula (I) were determined by the FZG A / 8,3 / 90 method at low loads.

[0195] The lubricating compositions described in Table 3 were subjected to the FZG A / 8,3 / 90 method (according to standard ISO 14635-1). The results are shown in Table 3 herein.

[0196] At equal concentrations of phosphorus, composition CI1 according to the invention has better antiwear properties than composition CC1.

Claims

1. Use of at least one antiwear additive selected from the group consisting of phosphated antiwear additives, phosphosulfurized antiwear additives, phosphamidized antiwear additives, sulfurized antiwear additives, boronized antiwear additives and mixtures thereof for improving the thermal conductivity of a fluid comprising at least one base oil.

2. Use of at least one antiwear additive according to claim 1 for improving the heat transfer properties of the fluid.

3. Use of at least one antiwear additive according to claim 1 or 2, wherein the fluid is used for cooling a battery of an electric vehicle.

4. Use of at least one antiwear additive according to any one of claims 1 to 3 for preparing a single fluid for lubricating and cooling a propulsion system of an electric vehicle.

5. Use of at least one antiwear additive according to any one of claims 1 to 4, wherein the antiwear additive is selected from phosphated antiwear additives, phosphosulfurized antiwear additives, phosphamidized antiwear additives and mixtures thereof, preferably selected from phosphated antiwear additives.

6. Use of at least one antiwear additive according to any one of claims 1 to 5, wherein the antiwear additive is a phosphite polymer, preferably corresponding to formula (I): Formula (I) in, -R 1 , R 2 , R 3 and R 4 Each of which can be independently selected from C1-C20 alkyl, C3-C22 alkenyl, C6-C40 cycloalkyl, C7-C40 cycloalkenyl, C1-20 methoxyalkyl glycol ether and Y-OH part; -Y is selected from C2-C40 alkylene, C2-C40 alkyl lactone moiety, -R 7 -N(R 8 )-R 9 Group, where R 7 , R 8 and R 9 are independently selected from hydrogen, C1-C20 alkyl, C3-C22 alkenyl, C6-C40 cycloalkyl, C7-C40 cycloalkenyl, C1-20 methoxyalkyl glycol ether moiety, -m is an integer from 2 to 100, -n is an integer from 1 to 1000.

7. Use of at least one antiwear additive according to claim 6, wherein the weight average molecular weight of the phosphite polymer preferably corresponding to formula (I) is less than 30000 g / mol, preferably in the range of 5000 g / mol to 20000 g / mol.

8. Use of at least one antiwear additive according to any one of claims 1 to 7, wherein the antiwear additive represents 0.01 to 10% by weight of the total weight of the fluid.

9. Use of at least one antiwear additive according to any one of claims 1 to 8, wherein the antiwear additive comprises from 5 ppm to 9150 ppm by weight of phosphorus, preferably from 5 ppm to 4500 ppm by weight of phosphorus, relative to the total weight of the fluid.

10. Use of at least one antiwear additive according to any one of claims 1 to 9, wherein the fluid comprises at least 70% by weight, preferably at least 80% by weight, more preferably at least 85% by weight of base oil relative to the total weight of the fluid.

11. Use of at least one antiwear additive according to any one of claims 1 to 10, wherein: Relative to the total weight of the fluid, the fluid comprises: - 70% to 99.99% by weight of one or more base oils, and - 0.01 to 10% by weight of an antiwear additive, preferably selected from phosphated antiwear additives, more preferably selected from phosphite polymers, - Optionally, 1 to 30% by weight of one or more functional additives, preferably selected from viscosity index improvers, antioxidant additives, defoaming additives, dispersants, detergents, viscosity improver additives and mixtures thereof.

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