Aqueous composition for the lubrication of a motorized system

Abstract

The present invention relates to an aqueous lubricating composition for lubricating fixed or mobile motorized systems, which comprises at least: deionized water; at least one polyalkylene glycol; at least one antifreeze compound selected from diols and at least one phosphorus-containing compound. The present invention also relates to the use of such an aqueous lubricating composition for lubricating and cooling fixed or mobile motorized systems.

Description

Field of the Invention

[0001] The present invention relates to the field of lubricating compositions, in particular lubricating compositions for lubricating mechanical systems such as rolling bearings, gear mechanisms, bearings or engines. In particular, the present invention relates to aqueous-based lubricating compositions for lubricating mobile or stationary motorized systems. Background of the Invention

[0002] Lubricating compositions, also known as "lubricants", are generally used in mechanical systems to reduce friction between components and thus protect the components from wear. In addition to the wear phenomenon, friction also hinders the relative movement between the contacting components and causes energy losses that are harmful to the optimal operation of the mechanical system.

[0003] Lubricants are used in a variety of applications, such as for metalworking, especially for metal deformation operations, for gas turbines or steam turbines in the fields of aviation, shipping, rail transportation and power generation, and for the propulsion systems of motor vehicles, such as for lubricating rolling bearings, gear mechanisms, engines, etc.

[0004] For example, in the field of lubricants for the engines or transmissions of motor vehicles, the formulation of lubricants is an important issue because they can affect fuel consumption and thus carbon dioxide emissions by influencing the frictional forces generated between different components of the motor vehicle.

[0005] The most common lubricants are hydrocarbon-based lubricants. These hydrocarbon-based lubricants usually consist of one or more base oils, and usually a variety of additives are combined with the base oil, and the additives are dedicated to stimulating the lubricating properties of the base oil, such as friction improvement additives.

[0006] In addition, the friction between moving parts generates heat, and it may be necessary to ensure the cooling of the mechanical system concomitantly. This cooling is usually provided by a cooling fluid different from the hydrocarbon-based lubricant, such as air, an aqueous fluid such as water, or a mixture of water and glycol.

[0007] Today, the development of new lubricants must take into account new restrictions to avoid using toxic or potentially toxic solvents, or to reduce their environmental impact and carbon dioxide emissions. Therefore, water-based formulations are attracting increasing attention.

[0008] Although water is an excellent cooling fluid, it does not possess the tribological properties required for a lubricant, especially in terms of reducing friction and protecting components from wear.

[0009] Water-based lubricating compositions supplemented with various additives have been studied. For example, document US 2012 / 0149616 proposes an aqueous lubricant which, in addition to water, contains a water-soluble polyalkylene glycol, an emulsifier, an alkylene glycol or glycerol-type anti-freeze additive, a corrosion inhibitor additive, an anti-foaming additive and an anti-friction additive. Summary of the Invention

[0010] Overview of the Invention

[0011] The present invention aims to provide a novel water-based composition having tribological properties suitable for use in lubricating mechanical systems.

[0012] More particularly, according to a first aspect thereof, the present invention relates to an aqueous lubricating composition for lubricating stationary or mobile motorized systems, comprising at least:

[0013] - deionized water;

[0014] - at least one polyalkylene glycol;

[0015] - at least one anti-freeze compound selected from glycols, preferably alkylene glycols; glycerol; diglycerol; triglycerol, and mixtures thereof; and

[0016] - at least one phosphorus-containing compound.

[0017] The term "aqueous composition" in the context of the present invention is understood to mean a composition comprising water as a base fluid (in other words as the main solvent). In particular, water (preferably deionized water) preferably accounts for more than 35% by mass of the total weight of the lubricating composition.

[0018] The term "osmotic water" in the context of the present invention is understood to mean water that has been purified, in particular by reverse osmosis, to reduce the content of organic and / or mineral compounds, for example to a content of less than 5.0% by weight, preferably less than 1.0% by weight. In the remainder of this text, the expressions "demineralized water" or "ultrapure water" will be considered equivalent or synonymous with the expression "osmotic water". In particular, osmotic water can be "deionized water", in other words water that has been purified to reduce the content of ions such as Ca 2+ and HCO3 - ions. Preferably, deionized water is ion-free.

[0019] In the remainder of this text, an "aqueous lubricating composition" or an "aqueous lubricant" means a lubricating composition according to the present invention, intended for lubricating moving parts in a mechanical system, more particularly intended for lubricating mobile or stationary motorized systems.

[0020] The term "motorization system (système de motorisation)" in the meaning of the present invention is understood to mean a system that includes all the mechanical components required for intended mobile or stationary applications and includes at least one engine. It can be an internal combustion, gas (especially hydrogen, ammonia), electric or hybrid motorization system, depending on the nature of the one or more engines included in the motorization system: internal combustion engine, gas (hydrogen, ammonia) engine and / or electric motor.

[0021] A "mobile" motorization system is more particularly a motorization system used in vehicles (véhicules), including light vehicles, heavy vehicles, mobile machines called "off-road", or marine vehicles (véhicules marins).

[0022] A mobile motorization system thus more particularly corresponds to a propulsion system for a vehicle.

[0023] The term "propulsion system" in the meaning of the present invention refers to a system that includes the mechanical components necessary to propel a vehicle. This propulsion system thus more specifically includes an engine, a transmission and optionally a battery (batterie). The battery itself is usually composed of a set of electric accumulators also called battery cells (cellules).

[0024] Advantageously, this mobile motorization system is a propulsion system for an electric or hybrid vehicle. This propulsion system thus more specifically includes an electric motor, a rotor-stator assembly including power electronics (dedicated to speed regulation), a transmission and a battery.

[0025] The term "electric vehicle" in the meaning of the present invention refers to a vehicle that includes an electric motor as the sole propulsion means, as opposed to a hybrid vehicle that includes an internal combustion engine and an electric motor as a combined propulsion means.

[0026] The term "stationary" motorization system in the meaning of the present invention is a motorization system that includes a stationary engine. It can be applied, for example, to power generation equipment. It can in particular be a gas motorization system, especially a stationary gas engine.

[0027] Contrary to all expectations, the inventors have found that by adding to water a specific combination of at least one antifreeze compound selected from glycols, at least one phosphorus-containing compound and at least one polyalkylene glycol, it is possible to obtain an aqueous formulation having excellent tribological properties.

[0028] Advantageously, the aqueous lubricating composition according to the present invention thus exhibits performance equivalent to or even improved compared to that achieved using a conventional lubricant based on hydrocarbon oil in reducing the friction between moving parts in a mechanical system.

[0029] The aqueous compositions according to the invention have thus proven suitable for use as lubricants for lubricating moving parts in mechanical systems, and more particularly for lubricating mobile or stationary motorized systems. They can thus be used in any system and any application to replace conventional hydrocarbon-based lubricants. Examples of applications are given in the remainder of this text.

[0030] Thus, according to another aspect thereof, the present invention relates to the use of an aqueous lubricating composition according to the invention for lubricating moving parts in a mechanical system, and more particularly for lubricating a mobile or stationary motorized system.

[0031] The present application particularly relates to the use of an aqueous lubricating composition according to the invention for lubricating a mobile motorized system, in particular the propulsion system of a vehicle, and more particularly the propulsion system of an electric or hybrid vehicle.

[0032] The present application also relates to the use of an aqueous lubricating composition according to the invention for reducing the friction between moving parts in a mechanical system, in particular in a mobile or stationary motorized system, and more particularly in the propulsion system of a vehicle, and to the use of an aqueous lubricating composition according to the invention for reducing the wear of parts in a mechanical system, in particular in a mobile or stationary motorized system, and more particularly in the propulsion system of a vehicle.

[0033] According to another aspect thereof, the present invention also relates to a method for lubricating a mechanical system (or a part in a mechanical system), said mechanical system being in particular a mobile or stationary motorized system, and more particularly the propulsion system of a vehicle, the method comprising at least one step of bringing at least one part of said mechanical system into contact with an aqueous lubricating composition according to the invention.

[0034] Advantageously, the compositions according to the invention combine good cooling properties associated with the presence of water, and good tribological properties, in particular anti-friction and anti-wear properties. Thus, the aqueous compositions according to the invention can advantageously provide a dual function of lubrication and cooling.

[0035] Thus, the present invention also relates to the use of an aqueous lubricating composition according to the invention for lubricating and cooling moving parts in a mechanical system, in particular in a mobile or stationary motorized system, and more particularly in the propulsion system of a vehicle.

[0036] The present application particularly relates to the use of an aqueous lubricating composition according to the invention for lubricating and cooling a mobile motorized system, in particular the propulsion system of a vehicle and more particularly the propulsion system of an electric or hybrid vehicle.

[0037] It is thus possible to use the aqueous compositions according to the invention to avoid using two different fluids: on the one hand a cooling fluid and on the other hand a lubricating fluid.

[0038] In addition, the composition according to the invention has the advantage of being easy to formulate. In addition to the combined properties of cooling and lubrication, it also has good stability. Advantageously, it also has good anti-corrosion properties.

[0039] According to an application variant, the aqueous lubricating composition can be used to lubricate the engine or transmission in a motor vehicle. These uses include bringing at least one component of the engine or transmission, in particular the gearbox ( de vitesse) or the axles (ponts) into contact with the aqueous lubricating composition according to the invention.

[0040] The aqueous lubricating composition according to the invention advantageously makes it possible to effectively influence fuel consumption by acting on the frictional forces generated between the different components of the motor vehicle. In particular, the aqueous lubricating composition has proven to be particularly advantageous for reducing friction in the gearbox, in the axle differential and / or in the cylinder head.

[0041] By thus reducing the friction between the moving parts in the propulsion system of the vehicle, the lubricating composition according to the invention can not only reduce wear, but also limit the energy losses that lead to excessive fuel consumption.

[0042] The aqueous lubricating composition according to the invention thus advantageously has good performance (also known as "Fuel Eco" performance) in reducing the fuel consumption of a motor vehicle and actually helps to reduce CO2 emissions.

[0043] The invention thus relates, according to another aspect thereof, to the use of the aqueous lubricating composition according to the invention for reducing the fuel consumption of an engine lubricated with such a composition, in particular a vehicle engine.

[0044] The invention also relates to the use of the aqueous lubricating composition according to the invention for reducing the fuel consumption of a vehicle equipped with a transmission lubricated with such a composition, in particular an axle or a gearbox.

[0045] Other characteristics, variants and advantages of the aqueous lubricating composition according to the invention will become more apparent on reading the following description and examples, which are given by way of illustration and do not limit the invention.

[0046] The expressions "compris entre... et...", "allant de... à...", "formé de... à..." and "variant de... à..." are to be understood as including the boundary values, unless otherwise indicated.

[0047] In the specification and the examples, unless otherwise indicated, the percentages are by weight. The percentages are thus expressed as a mass relative to the total mass of the composition. Unless otherwise indicated, the temperature is in degrees Celsius and, unless otherwise indicated, the pressure is atmospheric pressure. Description of the Drawings

[0048] Figure 1 Shows the frictional torque measured by the "cylinder head bench" test for the composition (I1) according to the invention and the comparative composition (C1) in the rotational speed range from 400 rpm to 2000 rpm. Detailed Description

[0049] Detailed Explanation

[0050] aqueous composition

[0051] As mentioned above, the aqueous lubricating composition (also referred to as aqueous lubricant) according to the invention is a formulation comprising water (in particular deionized water) as the main solvent.

[0052] For the purposes of the present invention, "main solvent" is understood to mean that the amount of water present is greater than any other solvent that may be present in the composition. Preferably, the aqueous lubricating composition according to the invention comprises at least 35% by mass, preferably 35% - 90% by mass, more preferably 40% - 75% by mass of water, in particular deionized water, based on the total mass of the composition.

[0053] Advantageously, in addition to its role as a solvent, water also enables a lubricating composition with good cooling properties to be obtained, which can be used as a cooling fluid for moving parts in a mechanical system.

[0054] According to a particular embodiment, the water used in the aqueous lubricating composition according to the invention is deionized water, also known as demineralized water.

[0055] Deionized water does not contain ions such as Ca 2+ and HCO3 - ions, which cause electrical conduction in water.

[0056] The use of deionized water is thus particularly advantageous in the following applications: the use of the aqueous lubricant according to the invention in applications for fluids that require little or no electrical conductivity, such as the use of the aqueous lubricant for lubricating and cooling mechanical systems comprising an electrical circuit, such as in particular an electric or hybrid engine in an electric or hybrid vehicle.

[0057] The aqueous lubricating composition according to the invention thus differs from lubricants conventionally used in mechanical systems, which comprise a major proportion of one or more water-insoluble base oils.

[0058] "Water-insoluble oil" is understood to particularly mean an oil that is substantially insoluble in water at ambient temperature (about 25 °C). In particular, the water-insoluble oil has a solubility in water at ambient temperature of less than 0.2 g / L.

[0059] This particularly relates to lubricating base oils belonging to Groups I to V according to the categories defined in the API classification (or their equivalents according to the ATIEL classification) and mixtures thereof.

[0060] Preferably, the aqueous lubricating composition according to the invention comprises less than 5% by mass, preferably less than 2% by mass and more preferably less than 1% by mass of water-insoluble base oil relative to the total mass of the composition.

[0061] Advantageously, the aqueous lubricating composition according to the invention is completely free of water-insoluble oil.

[0062] polyalkylene glycol

[0063] As mentioned above, the aqueous lubricating composition according to the invention comprises at least one polyalkylene glycol.

[0064] The polyalkylene glycol (referred to as "PAG") is selected from water-soluble polyalkylene glycols.

[0065] The term "water-soluble" means a polyalkylene glycol that has a solubility in water at ambient temperature (about 25 °C) of at least 10 g / L, preferably at least 500 g / L.

[0066] The polyalkylene glycol may more particularly be formed from C1-C4, preferably C1-C3 and more particularly C2-C3 alkylene oxide units.

[0067] Advantageously, the polyalkylene glycol used in the aqueous lubricating composition according to the invention comprises at least 50% by mass, in particular at least 80% by mass, more preferably at least 90% by mass of propylene oxide and / or ethylene oxide units. It may be a copolymer of ethylene oxide / propylene oxide, in particular a random copolymer.

[0068] Preferably, the polyalkylene glycol used in the aqueous lubricating composition according to the present invention has a weight-average molar mass (Mn) between 1000 and 20000 g.mol -1 and preferably between 5000 and 15000 g.mol -1 between.

[0069] The number-average molar mass can be measured by gel permeation chromatography (GPC).

[0070] Preferably, the polyalkylene glycol used in the aqueous lubricating composition according to the present invention has a kinematic viscosity measured at 100 °C (KV100) according to ASTM D445 standard between 100 and 5000 mm 2 / s, especially between 150 and 3000 mm 2 / s, more especially between 500 and 3000 mm 2 / s.

[0071] Preferably, the polyalkylene glycol used in the aqueous lubricating composition according to the present invention has a kinematic viscosity measured at 40 °C (KV40) according to ASTM D445 standard between 500 and 30000 mm 2 / s, especially between 1000 and 25000 mm 2 / s, or even between 5000 and 25000 mm 2 / s.

[0072] The flash point of the polyalkylene glycol used in the aqueous lubricating composition according to the present invention is preferably higher than or equal to 160 °C, especially higher than or equal to 220 °C. The flash point can be measured by ISO 2592 or ASTM D92 standard.

[0073] Preferably, the polyalkylene glycol used in the aqueous lubricating composition according to the present invention has a viscosity index measured according to ASTM D2270 standard between 100 and 800, preferably between 250 and 550.

[0074] In particular, the one or more polyalkylene glycol compounds can be used in the aqueous lubricating composition according to the present invention in a content of at least 5.0% by mass, preferably between 5.0% and 50% by mass, more preferably between 10% and 40% by mass, especially between 15% by mass and 30% by mass, based on the total mass of the composition.

[0075] anti-freeze compound

[0076] As described above, the aqueous lubricating composition according to the present invention comprises at least one antifreeze compound selected from glycols, preferably alkylene glycols; glycerol; diglycerol; triglycerol, and mixtures thereof.

[0077] These compounds are known for their antifreeze action, i.e., they can be used to lower the freezing temperature of the composition.

[0078] The diol is a diol in which two hydroxyl groups are carried by different carbon atoms, preferably by adjacent carbon atoms.

[0079] Preferably, the diol is an alkylene diol, particularly having 2 - 10 carbon atoms, especially 2 - 6 carbon atoms. For example, monoethylene glycol, diethylene glycol, and propylene glycol can be mentioned.

[0080] The antifreeze compound can also be selected from glycerol, diglycerol, triglycerol, and mixtures thereof.

[0081] Preferably, the antifreeze compound used according to the present invention is selected from monoethylene glycol, diethylene glycol, propylene glycol, glycerol, and mixtures thereof. Preferably, the antifreeze compound is monoethylene glycol.

[0082] In particular, the antifreeze compound can be used in the aqueous lubricating composition according to the present invention in an amount of at least 5.0% by mass, preferably between 5.0% and 35% by mass, more preferably between 10% and 35% by mass, especially between 15% and 30% by mass, based on the total mass of the composition.

[0083] phosphorus-containing compound

[0084] The aqueous lubricating composition according to the present invention contains at least one phosphorus-containing compound, i.e., a compound containing at least one phosphorus atom. Preferably, the phosphorus-containing compound considered according to the present invention does not introduce sulfur.

[0085] The phosphorus-containing compound is advantageously used in a water-soluble or water-emulsifiable form, particularly in the form of an ionic salt.

[0086] In particular, the phosphorus-containing compound can be selected from phosphoric acid amines; phosphate esters or salts such as esters of phosphoric acid, especially alkyl, alkenyl, or aryl esters of phosphoric acid; polyphosphate esters; phosphonate esters such as esters of phosphonic acid, especially alkyl, alkenyl, or aryl esters of phosphonic acid; polyphosphonate esters; carbamoyl phosphoric acid; hypophosphite esters; and mixtures thereof.

[0087] The one or more phosphorus-containing compounds are preferably present in the aqueous lubricating composition according to the present invention in the form of salts, particularly in the form of phosphate, phosphonate, or hypophosphite ions neutralized by appropriate counterions.

[0088] The salts can be alkali metal or alkaline earth metal salts, ammonium salts, alkanolamine salts, especially C2 - C8 alkanolamine salts, or alkaneamine salts, especially C2 - C8 alkaneamine salts of phosphoric acid, phosphonic acid, or hypophosphorous acid.

[0089] Examples of compounds which are very particularly suitable for the present invention are phosphates, phosphonates and their salts, preferably phosphates and their salts.

[0090] Phosphates, also known as esters of phosphoric acid, can be obtained by reacting at least one optionally ethoxylated linear or branched alcohol, preferably at least one alcohol containing 1-18 carbon atoms, especially 1-14 carbon atoms, particularly 1-12 carbon atoms, more preferably 2-8 carbon atoms, with phosphorus pentoxide of the formula P2O5 or with phosphoric acid.

[0091] Preferably, the phosphorus-containing compounds used in the aqueous compositions according to the invention are selected from phosphates, especially alkyl, alkenyl or aryl phosphates, particularly aryl phosphates, more particularly ethoxylated aryl phosphates.

[0092] Such compounds can especially be selected from ethoxylated tridecanol phosphate, ethoxylated triphenylvinylphenol phosphate, and mixtures thereof.

[0093] Phosphates can be used especially in the form of pH-regulating additives in neutralized or acid form, said pH-regulating additives being especially selected from ethanolamines such as monoethanolamine (MEA), diethanolamine (DEA); triethanolamine (TEA), diethylene glycolamine (DGA) isopropanolamines, such as monoisopropanolamine (MIPA), diisopropanolamine (DIPA) and triisopropanolamine (TIPA), ethylenediamines, such as ethylenediamine (EDA), diethylenetriamine (DETA), triethylenetetramine (TETA) and tetraethylenepentamine (TEPA), alkanolamines, such as methyldiethanolamine (MDEA), cycloamines, such as cyclohexylamine, 2-amino-2-ethyl-1,3-propanediol, 2-amino-2-methyl-1-propanol and mixtures thereof.

[0094] Advantageously, the phosphorus-containing compounds used in the aqueous compositions according to the invention are selected from salts of phosphates, especially alkali metal salts of phosphates, especially C1-C8 alkyl or dialkyl phosphates.

[0095] Such compounds can especially be selected from potassium butyl phosphate, potassium dibutyl phosphate and mixtures thereof.

[0096] Some of these phosphorus-containing compounds have been proposed for use as antistatic agents in hydraulic fluids. However, to the knowledge of the present inventors, such compounds have never been used in aqueous lubricating compositions.

[0097] The aqueous lubricating composition according to the invention can comprise, relative to the total mass of the composition, less than 5.0% by mass, preferably 0.1%-5.0% by mass, more preferably 0.5%-3.0% by mass of the phosphorus-containing compounds as defined above, especially in the form of salts, especially in the form of salts of phosphates.

[0098] According to a particular embodiment, the aqueous lubricating composition according to the invention may comprise a phosphorus content of from 0.016% to 0.40% by mass, in particular from 0.04% to 0.24% by mass and more particularly from 0.08% to 0.16% by mass.

[0099] Advantageously, the aqueous lubricating composition according to the invention may comprise a phosphorus content of from 0.010% to 0.40% by mass, in particular from 0.014% to 0.16% by mass, more particularly from 0.04% to 0.10% by mass.

[0100] The phosphorus content can be measured by ICP (Inductively Coupled Plasma).

[0101] According to a particular embodiment, the aqueous lubricating composition according to the invention comprises:

[0102] - water, preferably deionized water;

[0103] - at least one polyalkylene glycol, in particular as defined above;

[0104] - at least one antifreeze compound selected from glycols, preferably alkylene glycols; glycerol; diglycerol; triglycerol, and mixtures thereof; preferably selected from monoethylene glycol, diethylene glycol, propylene glycol, glycerol and mixtures thereof, and

[0105] - at least one phosphorus-containing compound, particularly selected from phosphoric esters or salts thereof, particularly selected from:

[0106] - alkali metal salts of phosphoric esters, especially C1-C8 alkyl or dialkyl phosphoric esters, such as selected from potassium butyl phosphate, potassium dibutyl phosphate;

[0107] - ethoxylated alkyl, alkenyl or aryl phosphates, such as selected from ethoxylated tridecanol phosphate, ethoxylated triphenylvinylphenol phosphate; and

[0108] - mixtures thereof.

[0109] additive

[0110] The aqueous lubricating composition according to the invention may further comprise various additives.

[0111] It should be understood that the additives are compatible with their use in an aqueous medium. Advantageously, the additives are used in a water-soluble or water-emulsifiable form, for example in the form of ionic salts or liquids.

[0112] The additives are of course selected for the intended application of the aqueous lubricant.

[0113] Of course, those skilled in the art will note that the selection of possible additives and / or their amounts should be such that the advantageous properties of the aqueous lubricating composition according to the invention, in particular the tribological properties, in particular the properties of reducing friction and protecting components against wear, as well as the cooling properties, are not adversely affected by the addition of the proposed additives.

[0114] Such additives may more particularly be selected from defoamers, biocides, pH regulators, corrosion inhibitors, antiwear and / or extreme pressure additives, chelating agents, metal deactivators, colorants, dispersants, emulsifiers and mixtures thereof.

[0115] Advantageously, the aqueous lubricating composition according to the invention may comprise one or more additives selected from defoamers, extreme pressure agents, corrosion inhibitors, pH regulators, metal deactivators, colorants and mixtures thereof.

[0116] The aqueous lubricating composition according to the invention may more particularly comprise additives in an amount of 0.1% - 10% by mass, more preferably 1.0% - 8.0% by mass, based on the total mass of the composition.

[0117] corrosion inhibitor

[0118] The aqueous lubricating composition according to the invention may comprise at least one corrosion inhibitor. The corrosion inhibitor advantageously makes it possible to reduce or even prevent the corrosion of metal components. The nature of the corrosion inhibitor may be selected according to the metal to be protected against corrosion, such as aluminium, steel, galvanized steel, yellow metals such as copper or brass.

[0119] Among the inorganic corrosion inhibitors, mention may be made of nitrites, sulphites, silicates, borates, sodium, potassium, calcium or magnesium phosphate salts, alkali metal phosphates, hydroxides, molybdates, zinc, magnesium or nickel sulphate salts.

[0120] Among the organic corrosion inhibitors, mention may be made of alkanolamines such as triethanolamine, aliphatic monocarboxylic acids having in particular 4 - 15 carbon atoms such as octanoic acid, aliphatic dicarboxylic acids having 4 - 15 carbon atoms such as sebacic acid, undecanedioic acid, dodecanedioic acid or mixtures thereof, polycarboxylic acids optionally neutralized with triethanolamine, such as 1,3,5 - triazine - 2,4,6 - tris(6 - aminohexanoic) acid, alkanoyl amidocarboxylic acids, in particular isononanoyl amidocaproic acid and mixtures thereof. Boron acid amides produced by the reaction of amines or amino alcohols with boric acid may also be used.

[0121] The aqueous lubricating composition according to the invention may particularly comprise a corrosion inhibitor in an amount of 0.1% - 5% by mass, preferably 0.5% - 4% by mass, more preferably 1% - 2.5% by mass, based on the total mass of the composition.

[0122] anti-wear / extreme pressure additive

[0123] The aqueous lubricating composition according to the invention may comprise at least one antiwear and / or extreme pressure additive. Their function is to reduce wear and the coefficient of friction, or to prevent metal-metal contact by forming an adsorbed protective film on these surfaces.

[0124] There is a wide variety of antiwear additives, among which those selected from phosphorus-sulfur additives such as metal alkyl thiophosphates or their salts may be mentioned.

[0125] Additives that do not provide phosphorus may also be suitable, such as polysulfides, especially sulfur-containing olefins.

[0126] According to a particular embodiment, the aqueous lubricating composition according to the invention comprises at least one extreme pressure additive selected from sulfur-containing fatty acids and dimercapto thiadiazole, preferably used in their neutralized, water-emulsifiable or water-soluble form. Advantageously, the aqueous lubricating composition according to the invention comprises at least one extreme pressure additive of the following type: sulfur-containing fatty acids, preferably in neutralized form, especially in the form neutralized with an inorganic basifying agent or an alkanolamine.

[0127] The sulfur-containing fatty acids may contain 8-22 carbon atoms, preferably 12-18 carbon atoms.

[0128] The amount of sulfur according to the ASTM D2622 standard provided by the said sulfur-containing fatty acids may be 5%-30% by mass, especially 10%-20% by mass.

[0129] Preferably, the amount of active sulfur at 150 °C according to the ASTM D1662 standard provided by the sulfur-containing fatty acids in the aqueous lubricating composition according to the invention, relative to the total mass of the lubricating composition, is greater than or equal to 2% by mass, especially 5%-10% by mass.

[0130] The term "active sulfur" in the context of the present invention is understood to mean the sulfur that a compound is capable of generating or releasing when the compound is placed under the conditions of the ASTM D1662 standard. The ASTM D1662 standard defines the active sulfur content of a compound at a given temperature as the difference, expressed as a percentage by weight, in the sulfur content before and after a sample of the sulfur-containing compound reacts with a given amount of copper over a fixed period of time.

[0131] The amount of active sulfur at 150 °C (ASTM D1662 standard) in the aqueous lubricating composition of the present invention affects its extreme pressure performance. The active sulfur content at 150 °C (ASTM D1662 standard) in this lubricating composition must not be too low, otherwise satisfactory extreme pressure performance cannot be obtained. It also cannot be too high to avoid the risk of corrosion, especially for metals and metal alloys, especially for copper.

[0132] As described above, the sulfur-containing fatty acid is preferably used in the aqueous lubricating composition of the present invention in the form of its neutralization by a basifying agent, such as sodium hydroxide, potassium hydroxide or alkanolamines such as monoethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine and triisopropanolamine.

[0133] The aqueous lubricating composition according to the present invention may comprise an antiwear and / or extreme pressure additive in an amount of from 0.01% to 10% by mass, preferably from 0.2% to 5% by mass, based on the total mass of the composition, in particular the sulfur-containing fatty acid as described above.

[0134] defoamer

[0135] The aqueous lubricating composition according to the present invention may comprise at least one defoaming additive. The defoaming agent can prevent the lubricating fluid from foaming.

[0136] It may be, for example, a defoaming agent based on polysiloxane or acrylate polymer. Preferably, the defoaming agent is selected from three-dimensional siloxanes.

[0137] In addition, the defoaming agent may be a polar polymer, such as polymethylsiloxane or polyacrylate.

[0138] In particular, the aqueous lubricating composition according to the present invention may comprise a defoaming additive in an amount of from 0.001% to 3.0% by mass, preferably from 0.005% to 1.5% by mass, more preferably from 0.01% to 1.0% by mass, based on the total mass of the composition.

[0139] pH regulator

[0140] The aqueous lubricating composition according to the present invention may comprise at least one pH-adjusting additive, in particular an alkaline buffer. The pH regulator makes it possible to maintain the desired pH of the lubricating composition, in particular in order to maintain an alkaline pH, advantageously between 8 and 11, thereby in particular preventing the corrosion of metal surfaces.

[0141] The pH regulator may be selected from amines, in particular alkanolamines and amino alcohols.

[0142] It may in particular be a pH-adjusting additive selected from: ethanolamines, such as monoethanolamine (MEA), diethanolamine (DEA); triethanolamine (TEA), diethylene glycolamine (DGA) isopropanolamines, such as monoisopropanolamine (MIPA), diisopropanolamine (DIPA) and triisopropanolamine (TIPA), ethylenediamines, such as ethylenediamine (EDA), diethylenetriamine (DETA), triethylenetetramine (TETA) and tetraethylenepentamine (TEPA), alkanolamines, such as methyldiethanolamine (MDEA), cycloamines, such as cyclohexylamine, 2-amino-2-ethyl-1,3-propanediol, 2-amino-2-methyl-1-propanol and mixtures thereof.

[0143] The aqueous lubricating composition according to the present invention may particularly comprise a pH adjusting additive in an amount of 0.1% to 10% by mass, preferably 0.5% to 5% by mass, based on the total mass of the composition.

[0144] metal deactivator

[0145] The aqueous lubricating composition according to the present invention may comprise at least one metal deactivator. The metal deactivator can protect metal components by promoting the formation of metal oxides on their surfaces.

[0146] The metal deactivator can be selected, for example, from triazole derivatives such as tetrahydrobenzotriazole (THBTZ), tolyltriazole (TTZ), benzotriazole (BTZ), amines substituted with triazole groups such as N,N-bis(2-ethylhexyl)-1,2,4-triazol-1-ylmethanamine, N'-bis(2-ethylhexyl)-4-methyl-1H-benzotriazole-1-methanamine, N,N-bis(heptyl)-ar-methyl-1H-benzotriazole-1-methanamine, N,N-bis(nonyl)-ar-methyl-1H-benzotriazole-1-methanamine, N,N-bis(decyl)-ar-methyl-1H-benzotriazole-1-methanamine, N,N-bis(undecyl)-ar-methyl-1H-phenyltriazole-1-methanamine, N,N-bis(dodecyl)-ar-methyl-1H-benzotriazole-1-methanamine, N,N-bis(2-ethylhexyl)-ar-methyl-1H-benzotriazole-1-methanamine, 1,2,4-triazole, benzimidazole, 2-alkyldithiobenzimidazole, 2-alkyldithiobenzothiazole, 2-(N,N-dialkyldithiocarbamoyl)benzothiazole, 2,5-bis(alkyldithio)-1,3,4-thiadiazole such as 2,5-bis(trioctyldithio)-1,3,4-thiadiazole, 2,5-bis(trinonyldithio)-1,3,4-thiadiazole, 2,5-bis(tridecyldithio)-1,3,4-thiadiazole, 2,5-bis(tridecyldithio)-1,3,4-thiadiazole, 2,5-bis(tridodecyldithio)-1,3,4-thiadiazole, 2,5-bis(tridodecyldithio)-1,3,4-thiadiazole, 2,5-bis(tritridecyldithio)-1,3,4-thiadiazole, 2,5-bis(tetradecyldithio)-1,3,4-thiadiazole, 2,5-bis(pentadecyldithio)-1,3,4-thiadiazole, 2,5-bis(hexadecyldithio)-1,3,4-thiadiazole, 2,5-bis(heptadecyldithio)-1,3,4-thiadiazole, 2,5-bis(octadecyldithio)-1,3,4-thiadiazole, 2,5-bis(nonadecyldithio)-1,3,4-thiadiazole, 2,5-bis(eicosyldithio)-1,3,4-thiadiazole, 2,5-bis(N,N-dialkyldithiocarbamoyl)-1,3,4-thiadiazole, 2-alkyldithio-5-mercaptothiadiazole, and mixtures thereof.

[0147] Preferably, the metal deactivator is selected from tetrahydrobenzotriazole (THBTZ), tolyltriazole (TTZ), benzotriazole (BTZ) and salts thereof, used alone or as a mixture.

[0148] The aqueous lubricating composition according to the present invention may particularly contain 0.01% - 2.0% by mass, preferably 0.1% - 1.0% by mass, more preferably 0.2% - 0.8% by mass of the metal deactivator based on the total mass of the composition.

[0149] colorant

[0150] The aqueous lubricating composition according to the invention may comprise one or more colorants. The colorants may be natural or synthetic, and are generally organic.

[0151] The colorants that can be used in the aqueous lubricating composition may more particularly be selected from natural or synthetic water-soluble colorants such as Colorant FDC Red 4, DC Red 6, DC Red 22, DC Red 28, DC Red 30, DC Red 33, DC Orange 4, DC Yellow 5, DC Yellow 6, DC Yellow 8, FDC Green 3, DC Green 5, FDC Blue 1, betanin (beet), carmine, chlorophyllin, methylene blue, anthocyanins (anthocyanosides, black carrots and hibiscus), caramel and riboflavin.

[0152] The aqueous lubricating composition according to the invention may comprise a colorant in an amount of 0.01% - 2.0% by mass, preferably 0.01% - 1.5% by mass, more preferably 0.02% - 1.0% by mass, based on the total mass of the composition.

[0153] emulsifier

[0154] The aqueous lubricating composition according to the invention may comprise one or more emulsifiers, also known as emulsifying agents. Their role is to form a stable emulsion in water.

[0155] The emulsifiers may more particularly be nonionic, such as ethoxylated fatty alcohols, ethoxylated fatty acids, ethoxylated fatty amides; anionic, such as soaps of KOH or NaOH; sulfonates; cationic, such as quaternary ammonium compounds; or water-soluble or water-emulsifiable carboxylic acid esters.

[0156] In particular, the aqueous lubricating composition according to the invention may comprise an emulsifier in an amount of 0.01% - 10% by mass, preferably 0.1% - 5.0% by mass, based on the total mass of the lubricating composition.

[0157] chelating agent

[0158] The aqueous lubricating composition according to the invention may comprise at least one chelating agent. The chelating agent (also known as a chelating reagent) enables the scaling of metal ions in the composition to be restricted.

[0159] As examples of chelating agents, those derived from phosphonic acids and phosphonates can be mentioned, such as diethylenetriamine pentamethylphosphonic acid (DTPMPA), aminotris(methylenephosphonic acid) (ATMP), hydroxyethane diphosphonic acid (HEDP), 1-hydroxyethylidene-1,1-diphosphonate, 2-hydroxyethylamine di(methylenephosphonic acid) (HEAMBP), diethylenetriamine penta(methylenephosphonic acid) (DTMP), polyfunctional organic acids and hydroxy acids such as ethylenediaminetetraacetic acid (EDTA), pteroyl-L-glutamic acid (PGLU), organic polyacids such as maleic acid and polyaspartic acid, polysaccharides and carbohydrates such as inulin, carboxymethyl inulin and carboxymethyl chitosan.

[0160] The aqueous lubricating composition according to the invention may comprise from 0.001% to 2.0% by mass, preferably from 0.01% to 1.0% by mass, of a chelating agent, based on the total mass of the composition.

[0161] biocide and fungicide

[0162] The aqueous lubricating composition according to the invention may comprise at least one biocide and / or fungicide. Biocides and fungicides can be used to improve the biostability of the composition by limiting the proliferation of bacteria, fungi and yeasts in the lubricating fluid.

[0163] Such biocides may be selected from parabens, aldehydes, reactive acetylacetone compounds, isothiazolinones, phenolic compounds, acid salts, halogenated compounds, quaternary ammonium, certain alcohols and mixtures thereof.

[0164] Preferably, the biocide may be selected from optionally substituted benzisothiazolinone (BIT), such as N-butyl-1,2-benzisothiazolin-3-one, methylisothiazolinone (MIT), a mixture of methylisothiazolinone and chloromethylisothiazolinone (MIT / CMIT), o-phenylphenol (OPP) or its sodium salt, 3-iodo-2-propynyl butylcarbamate (IPBC), chlorocresol and N,N-methylenebis(morpholine) (MBM); sorbic acid; preferably selected from o-phenylphenol (OPP) or its sodium salt, 3-iodo-2-propynyl butylcarbamate, chlorocresol, benzisothiazolinone and N,N-methylenebis(morpholine).

[0165] The aqueous lubricating composition according to the invention may particularly comprise from 0.01% to 10% by mass, preferably from 0.5% to 5.0% by mass, of a biocide and / or fungicide, based on the total mass of the composition.

[0166] According to a particular embodiment, the aqueous lubricating composition according to the invention comprises:

[0167] - at least 35% by mass of water, preferably deionized water;

[0168] - At least one polyalkylene glycol in an amount of 5.0% - 50% by mass, in particular as defined above;

[0169] - At least one antifreeze compound in an amount of 5.0% - 35%, selected from glycols, preferably alkylene glycols; glycerol; diglycerol; triglycerol and mixtures thereof; preferably selected from monoethylene glycol;

[0170] - At least one phosphorus-containing compound in an amount of 0.1% - 10% by mass, particularly selected from phosphate esters and their salts, particularly selected from:

[0171] - Alkali metal salts of phosphate esters, especially C1 - C8 alkyl or dialkyl phosphate esters, such as selected from potassium butyl phosphate, potassium dibutyl phosphate;

[0172] - Ethoxylated alkyl, alkenyl or aryl phosphate esters, such as selected from ethoxylated tridecyl alcohol phosphate ester, ethoxylated triphenylvinylphenol phosphate ester; and

[0173] - Mixtures thereof.

[0174] - Optionally, one or more additives in an amount of 0.1% - 10% by mass, selected from defoamers, extreme pressure agents, corrosion inhibitors, pH regulators, metal passivators, colorants, emulsifiers, chelating agents and mixtures thereof.

[0175] The contents are expressed relative to the total mass of the lubricating composition.

[0176] In particular, the aqueous lubricating composition according to the invention may consist of:

[0177] - At least one polyalkylene glycol in an amount of 5.0% - 50% by mass, in particular as defined above;

[0178] - At least one antifreeze compound in an amount of 5.0% - 35%, selected from glycols, preferably alkylene glycols; glycerol; diglycerol; triglycerol and mixtures thereof; preferably selected from monoethylene glycol;

[0179] - At least one phosphorus-containing compound in an amount of 0.1% - 10% by mass, particularly selected from phosphate esters and their salts, particularly selected from:

[0180] - Alkali metal salts of phosphate esters, especially C1 - C8 alkyl or dialkyl phosphate esters, such as selected from potassium butyl phosphate, potassium dibutyl phosphate;

[0181] - Ethoxylated alkyl, alkenyl or aryl phosphate esters, such as selected from ethoxylated tridecyl alcohol phosphate ester, ethoxylated triphenylvinylphenol phosphate ester; and

[0182] - Mixtures thereof.

[0183] - Optionally, 0.1% - 10% by mass of one or more additives selected from defoamers, extreme pressure agents, corrosion inhibitors, pH regulators, metal passivators, colorants, emulsifiers, chelating agents, and mixtures thereof.

[0184] The content is expressed relative to the total mass of the lubricating composition.

[0185] The balance consists of water, preferably deionized water.

[0186] Advantageously, the lubricating composition according to the invention has a kinematic viscosity measured at 40 °C (KV40) according to standard ASTM D445 (ISO 3104) of 10 - 1000 mm 2 / s, especially 20 - 300 mm 2 / s, more especially 25 - 80 mm 2 / s.

[0187] The kinematic viscosity of the lubricating composition according to the invention measured at 100 °C (KV100) according to standard ASTM D445 (ISO 3104) can advantageously be 3 - 50 mm 2 / s, especially 4 - 25 mm 2 / s, particularly 5 - 10 mm 2 / s.

[0188] Advantageously, the lubricating composition according to the invention has a kinematic viscosity measured at - 10 °C (KV - 10) according to standard ASTM D445 (ISO 3104) of 200 - 600 mm 2 / s, especially 250 - 500 mm 2 / s, more especially 275 - 400 mm 2 / s.

[0189] application

[0190] As described above, the aqueous lubricating composition formulated according to the invention (especially as described above) has excellent tribological properties, especially in terms of reducing friction and anti - wear properties, which makes it particularly suitable for use as a lubricating fluid.

[0191] The aqueous lubricating compositions can be used in various applications. Generally, they can be used as lubricating fluids for systems and applications, replacing traditional hydrocarbon - based lubricants.

[0192] The aqueous lubricating composition according to the invention can thus be used for lubricating gear mechanisms, rolling bearings, bearings (such as rolling bearings or sliding bearings), or engines.

[0193] For example, the aqueous lubricating composition according to the invention can be used to lubricate mobile motorized systems, in particular to lubricate various components of a motor vehicle, in particular a transmission or an engine, and in particular the cylinder head of an internal combustion engine of a vehicle engine, for example. It advantageously makes it possible to reduce the friction between the components of the propulsion system of a vehicle (such as a transmission and an engine).

[0194] As mentioned above, the lubricating composition according to the invention has excellent performance in reducing fuel consumption ("fuel economy" performance).

[0195] Internal combustion engines are generally divided into a part called the "upper engine", which consists of at least one cylinder head assembled to the "lower engine". The cylinder head is the component that closes the top of the engine cylinder. It ensures the distribution of the intake air in the combustion chamber through the intake pipe and the intake valve, and ensures the discharge of the combustion gases through the exhaust pipe and the exhaust valve. As shown in the examples, the aqueous lubricating composition according to the invention can significantly reduce the friction in the cylinder head of a vehicle engine.

[0196] The lubricating composition according to the invention can also be used to lubricate the components of a motor vehicle transmission (in particular for transmissions for light or heavy vehicles), such as a gearbox and / or an axle.

[0197] In another application variant, the aqueous lubricating composition according to the invention can be used in metalworking, for example for processing metals such as aluminum, steel, galvanized steel, and yellow metals.

[0198] Advantageously, the lubricating composition according to the invention, which is mainly formed of water, has a very small toxicological impact, especially for the people using such a lubricant. Advantageously, even though water is the main solvent of the aqueous lubricant according to the invention, the treated surface is properly lubricated.

[0199] Furthermore, the presence of a large proportion of water makes it possible to more easily clean the surface to be treated, in particular by simply rinsing with water.

[0200] The aqueous lubricating composition according to the invention also has an advantageous application for lubricating the propulsion system of an electric or hybrid vehicle, and more particularly for lubricating the engine, the power electronics, the transmission, and / or the battery.

[0201] The aqueous composition according to the invention can thus be used both as a coolant and as a lubricant, for example in the propulsion system of an electric or hybrid vehicle. Advantageously, the composition according to the invention makes it possible to achieve good performance jointly in terms of cooling and lubricating the components of the propulsion system of an electric or hybrid vehicle.

[0202] More particularly, the composition according to the invention is capable of cooling and lubricating the electric motor of an electric or hybrid vehicle. It is particularly effective for cooling the power electronics and / or the rotor and / or the stator of the electric motor. It also ensures the lubrication of the rolling bearings located between the rotor and the stator of the electric motor of an electric or hybrid vehicle.

[0203] Advantageously, the composition according to the invention makes it possible to ensure the lubrication of the transmission (when it is present, in particular the reduction gear) of an electric or hybrid vehicle. Furthermore, the composition according to the invention advantageously makes it possible to effectively cool the battery present in an electric or hybrid vehicle.

[0204] Thus, advantageously, it is possible to ensure the cooling of the battery and the lubrication of the transmission (in particular the reduction gear) in an electric or hybrid vehicle, for example by using a single composition according to the invention.

[0205] According to the invention, the characteristics, advantages or preferred features of the composition according to the invention make it possible to define the characteristics, advantages and preferred features of the uses according to the invention.

[0206] The invention will now be described by means of the following examples, which are given by way of illustration of the invention without any doubt.

[0207] Examples

[0208] friction measurement

[0209] The performance of the composition in terms of friction reduction was measured using a cylinder head test bench.

[0210] The engine cylinder head was driven by a generator in order to measure the drive friction generated by the contact between the cam and the tappet via a torque sensor.

[0211] The tests were carried out at a fixed pressure of 2.5 - 3.5 bar and at two different temperatures:

[0212] - A temperature of -32°C - 40°C, called "low temperature"; and

[0213] - A temperature of -58°C - 62°C, called "high temperature".

[0214] A speed increase cycle was carried out for each temperature according to the following operating procedure:

[0215] - The cylinder head test bench was rinsed with a flushing oil containing a detergent additive and then with a reference lubricating composition;

[0216] - Once the first set point temperature was reached, the cylinder head inlet pressure was adjusted;

[0217] - When the set point temperature was reached, the control program was started;

[0218] - Successive platforms of approximately 60 seconds from 500 rpm to 2000 rpm, each platform increasing by 50 rpm gradually (i.e., 30 platforms in 60 seconds - the time interval between each platform lasts approximately 2 seconds);

[0219] - A 60 - second platform at 2000 rpm;

[0220] - Successive platforms of approximately 60 seconds from 2000 rpm to 500 rpm, each platform decreasing by 50 rpm gradually (i.e., again 30 platforms in 60 seconds - the time interval between each platform lasts approximately 2 seconds);

[0221] - Repeat the operating procedure for the next temperature by adjusting the set - point temperature to the desired temperature.

[0222] For each temperature and each speed platform, record the average frictional torque, the oil temperature at the cylinder head inlet, and the standard deviation of the torque measurement.

[0223] The values are calculated within the last 30 seconds of each platform and are the average of the last 2 cycles for each temperature.

[0224] At the end of the test: Stop the motor, then completely stop the test bench.

[0225] measurement of extreme pressure performance

[0226] According to ASTM D2783 standard, evaluate the anti - friction performance of the composition using two four - ball tests, and the following parameters apply to this test:

[0227] - The speed is close to 1500 rpm,

[0228] - The ambient temperature, i.e., approximately 20 °C,

[0229] - For the measurement of the welding load, the load duration is 1 minute, or for the measurement of the last load before seizure, the load duration is 10 seconds,

[0230] - The initial contact pressure is approximately 3.5 GPa.

[0231] The extreme - pressure measurement is carried out by rotating a stainless - steel ball on three stainless - steel balls (which remain stationary), and all four balls are completely coated with a lubricating film. A load is applied to the balls and increased gradually (starting from 10 kg and increasing by 10 kg) until the balls stick together. Replace the balls before each increase in load.

[0232] The extreme pressure capacity corresponds to the load value at which the four balls adhere, preventing the upper ball from rotating on the other three balls. The greater the load, the higher the extreme pressure capacity.

[0233] measurement of anti-wear performance

[0234] According to ASTM D2670 standard, the anti-wear performance of the lubricating composition of the present invention was evaluated using a FALEX friction meter under the following test conditions: Specimen: FALEX steel; Running-in period: 300 s; Test duration: 180 minutes; Running-in load: 445 N; Test load: 1335 N; Rotation speed: 290 rpm; and Ambient temperature.

[0235] Example 1

[0236] Preparation of the lubricating compositions according to the invention and comparative compositions

[0237] The aqueous lubricating composition (I1) according to the present invention and the comparative lubricating composition (C1) based on Group II and Group III base oils were formulated by simply mixing the following components shown in mass percentages in Table 1 below at ambient temperature. The percentages are thus expressed as mass relative to the total mass of the composition.

[0238] composition Composition (I1) according to the invention Comparative composition (C1) Group II base oil [%] - 71 Group III base oil [%] - 15 deionized water [%] 57.31 - polyalkylene glycol [%] 17.65 - monoethylene glycol [%] 20.52 - <![CDATA[8% (1) Alkali metal phosphate [%]]]> 1.0 - neutralized sulfur-containing fatty acid [%] 0.7 - anti-corrosion additive [%] 1.39 - deactivator [%] 0.33 - friction improver [%] - 0.5 pour point depressant additive [%] - 0.2 anti-oxidant additive [%] - 1.5 pH regulating additive [%] 1.07 - defoaming additive [%] 0.03 - colorant [%] 0.03 - additive package [%] - 12.3

[0239] (1) Phosphorus content of the phosphorus-containing compound [%]

[0240] Table 1

[0241] Example 2

[0242] Characterization of the compositions according to the invention and comparative compositions in terms of friction reduction

[0243] According to the measurement protocol defined above, the frictional torque caused by the aqueous lubricating composition (I1) according to the present invention was compared with the torque caused by the comparative oily lubricating composition (C1) at each speed and each temperature.

[0244] The results are summarized in Figure 1 and show the frictional torque of each composition in the speed range of 400 rpm to 1800 rpm at a given temperature. The lower the measured torque, the greater the friction reduction gain.

[0245] The torque value of the aqueous lubricating composition I1 according to the present invention is always lower than the torque value obtained for the comparative lubricating composition C1.

[0246] This shows that the aqueous lubricating composition I1 according to the present invention has a significant friction reduction gain compared to using a lubricating composition containing at least one hydrocarbon-based fluid (comparative composition C1).

[0247] Furthermore, the greater the friction reduction gain, the higher the fuel economy or Fuel-Eco. This thus means that the aqueous lubricating composition according to the present invention has improved performance in terms of fuel economy as compared to an oil-based lubricating composition.

[0248] Example 3

[0249] Preparation of the lubricating compositions according to the invention

[0250] Three lubricating compositions (I2, I3, and I4) according to the present invention were formulated by simply mixing at ambient temperature the following components shown in mass percentages in Table 2 below. The percentages are thus expressed in mass relative to the total mass of the composition.

[0251]

[0252] (1) Phosphorus content of the phosphorus-containing compound [%]

[0253] Table 2

[0254] Example 4

[0255] Characterization of the compositions according to the invention and comparative compositions in terms of extreme pressure and anti-wear performance

[0256] The extreme pressure and anti-wear properties of the lubricating compositions of the present invention according to the measurement protocol defined above.

[0257] The results are summarized in Table 3 below and show the seizure load value, the last load value before seizure, and the wear value (expressed in μm). The higher the load value, the better the extreme pressure performance. The lower the wear value, the better the anti-wear performance.

[0258]

[0259] Table 3

[0260] Compositions I1, I2, I3, and I4 according to the present invention have high load values and thus have very good extreme pressure performance.

[0261] Likewise, compositions I1, I2, I3, and I4 according to the present invention have low wear values and thus have very good anti-wear performance.

Claims

1. An aqueous lubricating composition for lubricating stationary or mobile motorized systems, comprising at least: - deionized water; - at least one polyalkylene glycol; - at least one antifreeze compound selected from glycols; glycerol; diglycerol; triglycerol, and mixtures thereof; and - at least one phosphorus-containing compound selected from salts of phosphoric acid esters.

2. The aqueous lubricating composition according to claim 1, comprising at least 35% by mass of deionized water, based on the total mass of the composition.

3. The aqueous lubricating composition according to claim 1, wherein the polyalkylene glycol comprises at least 50% by mass of propylene oxide and / or ethylene oxide units.

4. The aqueous lubricating composition according to claim 1, wherein the polyalkylene glycol has a kinematic viscosity measured at 100 °C (KV100) according to ASTM D445 standard between 100 and 5000 mm 2 / s.

5. The aqueous lubricating composition according to claim 1, comprising at least 5.0% by mass of polyalkylene glycol, based on the total mass of the composition.

6. The aqueous lubricating composition according to claim 1, wherein the antifreeze compound is selected from monoethylene glycol, diethylene glycol, propylene glycol, glycerol, and mixtures thereof.

7. The aqueous lubricating composition according to claim 1, comprising at least 5.0% by mass of antifreeze compound, based on the total mass of the composition.

8. The aqueous lubricating composition according to claim 1, comprising less than 5.0% by mass of phosphorus-containing compound, based on the total mass of the composition.

9. The aqueous lubricating composition according to claim 1, further comprising at least one additive selected from defoamers, biocides, pH regulators, corrosion inhibitors, antiwear and / or extreme pressure additives, chelating agents, metal deactivators, colorants, dispersants, emulsifiers, and mixtures thereof.

10. The aqueous lubricating composition according to claim 1, comprising at least one extreme pressure additive selected from sulfur-containing fatty acids and dimercaptothiadiazole.

11. The aqueous lubricating composition according to claim 1, comprising less than 5% by mass of water-insoluble oil, based on the total mass of the composition.

12. Use of the aqueous lubricating composition as defined in any one of claims 1-11 for lubricating mobile or stationary motorized systems.

13. Use according to claim 12, for lubricating the propulsion system of an electric or hybrid vehicle.

14. Use according to claim 12, wherein the motorization system is a hydrogen motorization system or an ammonia motorization system.

15. Use of an aqueous lubricating composition as defined in any one of claims 1 - 11 for lubricating and cooling a stationary or mobile motorization system.

16. Use according to claim 15, for lubricating and cooling the propulsion system of an electric or hybrid vehicle.

17. Use according to claim 15, wherein the motorization system is a hydrogen motorization system or an ammonia motorization system.

18. Use of an aqueous lubricating composition as defined in any one of claims 1 - 11 for reducing the fuel consumption of an engine or a vehicle equipped with a transmission, the engine or the transmission being lubricated by means of such a composition.

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