Lubricating fluids based on at least partly re-refined lubricating oils

Abstract

Title: Lubricating fluids based on at least partly re-refined lubricating oils The present application relates to the use of a composition based on at least one at least partly re-refined lubricating oil as a lubricating fluid. It also relates to a method for lubricating and advantageously for lubricating and cooling the components of a propulsion system of an electric or hybrid vehicle, said method comprising at least one step of bringing into contact at the level of said propulsion system a composition based on at least one at least partly re-refined lubricating oil.

Description

Title of the invention: Lubricating fluids based on at least partly re-refined lubricating oils Technical field

[0001] The present invention relates to the field of lubricating fluids. More specifically, the present invention relates to the use of re-refined lubricating oils for the formulation of a lubricating fluid and possibly cooling fluid for a propulsion system of electric or hybrid vehicles, in particular for the formulation of a single fluid for the lubrication and cooling of a propulsion system of electric vehicles. Prior art

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

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

[0004] Generally speaking, it is necessary to implement, in vehicles, lubricating compositions, also called "lubricating fluids", for the main purposes of reducing the friction forces between the different parts of the vehicle's propulsion system, in particular between the moving metal parts in the engines. These lubricating compositions are also effective in preventing premature wear or even damage to these parts, and in particular to their surface.

[0005] Electric motors generate heat during operation. If the amount of heat generated is greater than the amount of heat normally dissipated to the environment, it is necessary to ensure cooling of the motor. Generally, cooling is carried out on one or more parts of the motor generating heat and / or the parts of the motor sensitive to heat, in order to avoid reaching dangerous temperatures.

[0006] This cooling can be done by direct cooling or indirect cooling. Due to the growing increase in the power density of electric motors, it will be necessary to develop and improve the direct cooling mode of the electric motor where the lubricating fluid of the transmission part will also serve to cool the hot parts of the electric motor.

[0007] Water is commonly used as the base liquid of coolants, due to its natural availability and the lack of environmental impact of its implementation. In fact, water is an excellent carrier of thermal energy due to its high specific heat capacity, high thermal conductivity and low viscosity. A significant limitation of using water as a heat transfer fluid is that it freezes at a relatively high temperature of 0°C, making it unsuitable for use in many systems requiring operating temperatures below 0°C. In addition, water-based fluids are naturally corrosive and can cause significant damage to the systems in which they operate.To overcome these limitations, a large number of coolants have been developed in which freezing point depressants are added to the water to lower its freezing temperature, along with various additives to control corrosion.

[0008] Mineral oils derived from petroleum refining have also been proposed as base liquids for coolants, particularly for applications in systems in which the fluid is likely to be heated to high temperatures.

[0009] A non-aqueous lubricating composition is conventionally composed of one or more base oils, with which are generally associated several additives dedicated to stimulating the lubricating performance of the base oil, such as for example friction modifying additives.

[0010] However, a large amount of crude oil is generally required to obtain refined oils. Typically, to extract 1 liter of refined oil, 37 liters of crude oil are required. In addition, oil refining processes are very energy-intensive. However, current issues of environmental protection and resource conservation are pushing manufacturers to offer more eco-responsible alternative solutions to conventional oils.

[0011] For reasons of economy and ease of implementation, it would be advantageous to have a composition that can simultaneously meet the lubrication and cooling needs of a propulsion system (engine, battery, etc.) of an electric vehicle. Unfortunately, these two properties, lubrication and cooling, impose at first sight opposing constraints.

[0012] A particularly useful type of performance for a lubricating composition for electric vehicle propulsion systems consists of exhibiting good mechanical durability properties, properties which are systematically part of the prerogatives to be respected in the manufacturers' specifications.

[0013] Furthermore, this type of lubricating composition must be able to cool the propulsion systems of electric vehicles, in particular the battery of electric vehicles.

[0014] It is therefore an object of the present invention to provide a single fluid (unique lubricating composition) more environmentally friendly, while presenting excellent durability and cooling properties and can be implemented in all components of a propulsion system of an electric or hybrid vehicle. Statement of the invention

[0015] The present invention aims to propose new lubricating fluids meeting these expectations.

[0016] The invention relates to the use of a composition comprising at least one lubricating oil at least partly re-refined as a lubricating fluid for the lubrication of the components of a propulsion system of an electric or hybrid vehicle.

[0017] The invention may have one or more of the following characteristics:

[0018] - the composition is used as a lubricating fluid for the geared motor and as a fluid battery cooling; and / or

[0019] - the composition is used as a sole fluid for lubrication and cooling development of all the components of a propulsion system of an electric vehicle; and / or

[0020] - the composition makes it possible to improve the properties of mechanical durability, preferably both mechanical durability properties and cooling properties; and / or

[0021] - the at least partly re-refined lubricating oil comes from a used lubricant having been subjected to one or more prior stages of dehydration, distillation, filtration, hydrogenation, liquid / liquid extraction, decantation and / or passage of the used lubricant over an adsorbent material; and / or

[0022] - the composition has a kinematic viscosity measured at 40°C ranging from 12 to 26 mm2 / s, preferably from 15 to 25 mm2 / s, more preferably from 20.5 to 24 mm2 / s, or even from 21 to 24 mm2 / s, and / or

[0023] - the composition comprises:

[0024] - from 10 to 90% by weight, preferably from 20 to 80% by weight, more preferably from 30 to 70% by weight of a first lubricating oil at least partly re-refined having a kinematic viscosity at 40°C ranging from 5 to 20 mm2 / s, preferably from 10 to 16 mm2 / s, and

[0025] - from 10 to 90% by weight, preferably from 20 to 80% by weight, more preferably from 30 to 70% by weight of a second lubricating oil at least partly re-refined having a kinematic viscosity at 40°C ranging from 21 to 35 mm2 / s, preferably from 25 to 32 mm2 / s,

[0026] relative to the total weight of the composition; and / or

[0027] - the composition presents:

[0028] - a kinematic viscosity measured at 40°C ranging from 12 to 26 mm2 / s, in particular 15 to 25 mm2 / s, and

[0029] - a thermal conductivity, measured at 90°C and at atmospheric pressure, ranging from 115 to 140 mW / mK, in particular 120 to 130 mW / mK; and / or

[0030] - the composition has a sulfur content of between 0.01% and 0.2% mass, relative to the total mass of said at least partly re-refined lubricating oil, and / or

[0031] - the composition has a content of aromatic compound(s) greater than or equal to 0.5% by mass, in particular greater than or equal to 1% by mass, in particular between 1% and 25% by mass, more particularly between 2.5% and 20% by mass, relative to the total mass of said at least partly re-refined lubricating oil; and / or

[0032] - the composition has a density less than or equal to 870 kg / m3, in particular between 830 and 870 kg / m3, more particularly between 840 and 860 kg / m3; and / or

[0033] - the composition has a thermal conductivity, measured at 90°C and at pressure atmospheric, greater than or equal to 115 mW / mK, more particularly between 115 and 140 mW / mK; and / or

[0034] - said composition comprises one or more base oils distinct from the oil at least partly re-refined lubricant and / or one or more additives, in particular chosen from anti-corrosion additives, friction modifier additives, extreme pressure additives, anti-wear additives, detergents, antioxidants, viscosity index (VI) improvers, pour point depressants (PPD), dispersants, anti-foaming agents, and mixtures thereof; and / or

[0035] - said composition comprises more than 80% by mass, in particular between 90% and 100% by mass of one or more lubricating oils at least partly re-refined, relative to the total mass of said composition.

[0036] The invention also relates to a method for lubricating, preferably for lubricating and cooling, the components of a propulsion system of an electric vehicle, comprising at least one step of bringing into contact at the level of said system a composition based on at least one at least partly re-refined lubricating oil, in particular as defined in the invention, in particular having one or more of the following characteristics:

[0037] - the at least partly re-refined lubricating oil comes from a used lubricant having been subjected to one or more prior stages of dehydration, distillation, filtration, hydrogenation, liquid / liquid extraction, decantation and / or passage of the used lubricant over an adsorbent material; and / or

[0038] - the composition has a kinematic viscosity measured at 40°C ranging from 12 to 26 mm2 / s, preferably from 15 to 25 mm2 / s, more preferably from 20.5 to 24 mm2 / s, or even from 21 to 24 mm2 / s; and / or

[0039] - the composition comprises:

[0040] - from 10 to 90% by weight, preferably from 20 to 80% by weight, more preferably from 30 to 70% by weight of a first lubricating oil at least partly re-refined having a kinematic viscosity at 40°C ranging from 5 to 20 mm2 / s, preferably from 10 to 16 mm2 / s, and

[0041] - from 10 to 90% by weight, preferably from 20 to 80% by weight, more preferably from 30 to 70% by weight of a second lubricating oil at least partly re-refined having a kinematic viscosity at 40°C ranging from 21 to 35 mm2 / s, preferably from 25 to 32 mm2 / s,

[0042] relative to the total weight of the composition; and / or

[0043] - the composition presents:

[0044] - a kinematic viscosity measured at 40°C ranging from 12 to 26 mm2 / s, in particular 15 to 25 mm2 / s, and

[0045] - a thermal conductivity, measured at 90°C and at atmospheric pressure, ranging from 115 to 140 mW / mK, in particular 120 to 130 mW / mK; and / or

[0046] - the composition has a sulfur content of between 0.01% and 0.2% mass, relative to the total mass of said at least partly re-refined lubricating oil, and / or

[0047] - the composition has a content of aromatic compound(s) greater than or equal to 0.5% by mass, in particular greater than or equal to 1% by mass, in particular between 1% and 25% by mass, more particularly between 2.5% and 20% by mass, relative to the total mass of said at least partly re-refined lubricating oil; and / or

[0048] - the composition has a density less than or equal to 870 kg / m3, in particular between 830 and 870 kg / m3, more particularly between 840 and 860 kg / m3; and / or

[0049] - the composition has a thermal conductivity, measured at 90°C and at pressure atmospheric, greater than or equal to 115 mW / mK, more particularly between 115 and 140 mW / mK; and / or

[0050] - said composition comprises one or more base oils distinct from the oil at least partly re-refined lubricant and / or one or more additives, in particular chosen from anti-corrosion additives, friction modifier additives, extreme pressure additives, anti-wear additives, detergents, antioxidants, viscosity index (VI) improvers, pour point depressants (PPD), dispersants, anti-foaming agents, and mixtures thereof; and / or

[0051] - said composition comprises more than 80% by mass, in particular between 90% and 100% by mass of one or more lubricating oils at least partly re-refined, relative to the total mass of said composition.

[0052] More particularly, the inventors have discovered that the recycled lubricating base oils are particularly suitable for their implementation as lubricating fluids to improve the durability of the fluid, more specifically, the inventors have discovered that the recycled lubricating base oils are particularly suitable for their implementation as lubricating fluids and cooling fluids. Thus, the inventors have discovered that the recycled lubricating base oils are particularly suitable for their implementation as a single fluid that can be implemented in all the components of a propulsion system of an electric vehicle.

[0053] Thus, the invention relates, according to a first of its aspects, to the use of a composition based on at least one at least partly re-refined lubricating oil as a lubricating fluid for the lubrication of the components of a propulsion system of an electric vehicle, preferably as a lubricating fluid and cooling fluid for the lubrication and cooling of the components of a propulsion system of an electric vehicle.

[0054] In the context of the present invention, the expression “at least partly re-refined lubricating oil”, also referred to more simply in the remainder of the text as “re-refined oil”, “regenerated oil” or even “recycled oil”, designates an oil originating at least partly from a used lubricating composition having been subjected to one or more treatment steps known as re-refining treatment.

[0055] According to the invention, the term “used lubricating composition” (or more simply “used lubricant” or “used lubricating oil”) is intended to denote any lubricating composition that has been used for the lubrication of moving parts, in particular metal parts, of a mechanical system, such as, but not limited to, bearings, gears or motors.

[0056] Used lubricating oil can come from different sources. In particular, as detailed in the rest of the text, it can be a lubricant used for the lubrication of a motorization system, in particular “mobile”, or for the lubrication of a so-called industrial system, in particular “stationary”.

[0057] Due to their origin, used lubricating oils, in particular engine lubricating oils, include a number of degradation products derived from the oil itself or from the additives it contains, as well as metal particles, metal oxides and other elements, for example from the engine. A used oil may contain in particular a high content of undesirable elements, for example calcium (Ca), iron (Fe), magnesium (Mg), sodium (Na), nickel (Ni), phosphorus (P), silicon (Si), chlorine (Cl), zinc (Zn) etc.

[0058] Methods for re-refining or reconditioning used lubricating oils have been developed to regenerate these oils and allow their subsequent reuse.

[0059] A re-refined lubricating oil is thus an oil obtained at the end of one or more stages of treatment of a used lubricant, aimed at eliminating, at least in part, a certain number of contaminating elements present therein, such as dust, water, fuel fractions, metallic elements and other residues resulting from the degradation of the additives present in the lubricant.

[0060] To the inventors' knowledge, it has never been proposed to use a recycled lubricating oil to formulate a lubricating and cooling fluid for the lubrication and cooling of the components of a propulsion system of an electric or hybrid vehicle.

[0061] The use according to the invention of a re-refined lubricating oil as a lubricating fluid, advantageously as a lubricating fluid and cooling fluid, proves to be advantageous in several respects.

[0062] On the one hand, as illustrated in the examples which follow, the inventors have shown that the composition based on one or more re-refined lubricating oils has particularly advantageous durability properties, as well as particularly advantageous thermo-physical properties, in particular in terms of density and thermal conductivity, which make them particularly suitable as lubricating and cooling fluids.

[0063] Surprisingly, recycled lubricating oils even exhibit durability and thermo-physical properties for their use as lubricating and cooling fluid, identical or even superior to those of refined base oils, in other words virgin or new base oils.

[0064] A refined base oil, also called “virgin” or “new” base oil, unlike re-refined lubricating oils, is an oil directly derived from petroleum refining and which has not yet been used.

[0065] On the other hand, advantageously, the use of recycled lubricating oils as lubricating fluids meets current expectations for reducing environmental impact and conserving resources. Thus, the use of lubricating fluids based on regenerated lubricating oils advantageously makes it possible to reduce the carbon footprint of the products, compared to the use of virgin base oils.

[0066] Furthermore, the use of a single fluid to both lubricate and cool the components of a propulsion system of an electric or hybrid vehicle also makes it possible to reduce the carbon footprint.

[0067] As detailed in the rest of the text, said re-refined lubricating oil(s) can be used as such, i.e. alone, in other words without additives. tivation, as a lubricating fluid. In a particular embodiment, the invention thus relates to the use of at least one at least partly re-refined lubricating oil as a lubricating fluid for the lubrication of the components of a propulsion system of an electric or hybrid vehicle, preferably electric.

[0068] Said re-refined lubricating oil(s) may also be used in combination with one or more other ingredients. In particular, they may be ad-ditivated with one or more additives, for example intended to promote the compatibility of the lubricating fluid with the materials of the system for which it is intended, such as, for example and in a non-limiting manner, anti-corrosion additives, antioxidant additives, etc.

[0069] In the context of this embodiment variant, the lubricating fluid according to the invention is advantageously formed mainly from said re-refined lubricating oil(s). In particular, said re-refined lubricating oil(s) may represent more than 80% by mass of the total mass of the lubricating fluid, in particular more than 90% by mass of the total mass of the lubricating fluid.

[0070] Said re-refined lubricating oil(s) may also be used in combination with at least one new base oil.

[0071] The present invention also relates to the use of at least one at least partly re-refined lubricating oil for formulating or preparing a lubricating fluid for the lubrication of the components of a propulsion system of an electric or hybrid vehicle.

[0072] The present invention also relates to the use of at least one at least partly re-refined lubricating oil for formulating or preparing a lubricating and cooling fluid, also called a single fluid, for the lubrication and cooling of the components of a propulsion system of an electric or hybrid vehicle.

[0073] It also relates to a process or method for preparing a lubricating fluid, in particular a lubricating and cooling fluid, comprising at least one step consisting of obtaining a lubricating oil at least partly re-refined from a used lubricant.

[0074] The process for preparing a lubricating fluid according to the invention, in particular a lubricating and cooling fluid, may more particularly comprise the steps consisting of: (i) preparing one or more lubricating oil(s) at least partly re-refined from a used lubricant; (ii) optionally, mixing said at least partly re-refined lubricating oil with one or more new base oils, distinct from re-refined lubricating oils, for example one or more mineral oils; and (iii) optionally, supplementing said lubricating oil at least in part re- refined from step (i), or the mixture of lubricating oils from step (ii), with at least one additive, in particular chosen from anti-corrosion additives, friction modifier additives, extreme pressure additives, anti-wear additives, detergents, antioxidants, viscosity index (VI) improvers, pour point depressants (PPD), dispersants, anti-foaming agents, and mixtures thereof.

[0075] The invention also relates, according to another of its aspects, to the use of a lubricating fluid according to the invention, based on at least one at least partly re-refined lubricating oil, as the sole fluid for the lubrication and cooling of all the components of a propulsion system of an electric vehicle.

[0076] Furthermore, the invention also relates, according to another of its aspects, to the use of a lubricating fluid according to the invention, based on at least one at least partly re-refined lubricating oil, as lubricating fluid for the geared motor and as cooling fluid for the battery of a propulsion system of an electric vehicle.

[0077] The invention also relates to the improvement of mechanical durability properties, preferably the improvement of both mechanical durability properties and cooling properties by the use of a composition comprising one or more lubricating oils at least partly re-refined as defined in the present invention.

[0078] Other characteristics, variants and advantages of the use of at least partly re-refined lubricating oils for the formulation of a lubricating fluid according to the invention will become more apparent upon reading the description and examples which follow, given by way of illustration and not limitation of the invention.

[0079] The expressions “between ... and ...”, “ranging from ... to ...”, “formed from ... to ...”, and “varying from ... to ...”, must be understood inclusively, unless otherwise stated.

[0080] In the description and the examples, unless otherwise indicated, the percentages are mass percentages. The percentages are therefore expressed in mass relative to the total mass of the composition. Detailed description Lubricating oil at least partly re-refined

[0081] As previously specified, the oil used to formulate a lubricating fluid according to the invention is a lubricating oil that is at least partly re-refined, also called “regenerated oil” or “recycled oil”, in other words a lubricating oil from a used lubricating composition that has been subjected to one or more re-refining treatment steps can be used according to the invention.

[0082] It is understood that a used lubricating composition may be a mixture of several used lubricating compositions, from the same source or from several different sources.

[0083] Used lubricating compositions and, consequently, regenerated lubricating oils, comprise, in the majority quantity, one or more base oils conventionally used in the field of lubricants, such as mineral, synthetic or natural, animal or vegetable oils or their mixtures.

[0084] It may be a mixture of several base oils, for example a mixture of two, three, or four base oils.

[0085] These base oils may be of natural origin, for example from plants or animals, such as vegetable, animal, fish oils, and mixtures thereof. Examples of such oils are rapeseed oil, canola oil, tall oil, sunflower oil, soybean oil, hemp oil, olive oil, linseed oil, mustard oil, palm oil, peanut oil, castor oil, coconut oil, animal fats, and mixtures thereof.

[0086] Advantageously, these base oils are oils of mineral or synthetic origin belonging to groups I to V according to the classes defined in the API classification (or their equivalents according to the ATIEL classification) and presented in the following table, or their mixtures.

[0087] [Tables 1] Saturates content Sulphur content Viscosity index (VI) Group I Mineral oils < 90% > 0.03% 80 <VI < 120 Groupement II Huiles hydrocraquées >90% <0.03% 80 <VI < 120 Groupement III Huiles hydrocraquées ou hydro-isomérisées >90% <0.03% >120 Group IV Polyalphaolefins (PAO) Group V Esters and other bases not included in groups I to IV

[0088] In particular, the used lubricating composition, from which the regenerated lubricating oil used according to the invention is derived, may comprise at least 50% by weight of base oil(s) relative to its total weight, in particular at least 60% by weight of base oil(s), and more particularly between 60 and 99% by weight of base oil(s).

[0089] The re-refined lubricating oils used according to the invention advantageously have characteristics in terms of content of saturated compounds, sulfur content and viscosity index, satisfying the criteria defined by the API classification for oils of groups I, II, III, IV and / or V, in particular for oils of groups I, II, III and / or IV.

[0090] The invention thus aims at the use as lubricating fluid of a composition formed in whole or in part from at least one lubricating oil at least partly re-refined, obtained at the end of one or more stages of treatment of a used lubricant based on one or more oils from groups I to V according to the API classification.

[0091] According to a particular embodiment, the re-refined lubricating oil used according to the invention may come from the treatment of a used lubricating composition having been used for the lubrication of a motorization system, in particular “mobile”, that is to say including light vehicles, heavy goods vehicles, so-called “off-road” mobile machines, or even marine vehicles.

[0092] According to another particular embodiment, the re-refined lubricating oil used according to the invention may come from the treatment of a used lubricating composition having been used for the lubrication of a so-called industrial system, in particular “stationary”, that is to say including, in a non-limiting manner, turbines, compressors, hydraulic systems, gears, or even forming or cutting machines.

[0093] A used lubricating composition, from which the regenerated lubricating oil used according to the invention is derived, may contain various additives conventional in the field of lubricants, such as friction modifying additives, extreme pressure additives, anti-wear additives, detergents, antioxidants, viscosity index (VI) improvers, pour point depressant (PPD) additives, dispersing agents, anti-foaming agents, thickeners, and mixtures thereof.

[0094] As already mentioned previously, the properties of the used lubricating composition are degraded due to its use, for a more or less long period, for the lubrication and / or cooling of a mechanical system, in particular a motorization system, such as a combustion engine.

[0095] Due to their origin, used lubricating compositions may thus contain one or more additives described above and impurities resulting from the degradation of additives originally present in the lubricant, or resulting from the wear of moving mechanical parts.

[0096] The composition of the used lubricant can of course be different depending on the origin of the lubricant, its initial formulation and the fact that it may have been contaminated differently depending on its use.

[0097] The regenerated lubricating oil used according to the invention comes more particularly from a used lubricating composition having been subjected to one or more prior pre-treatment steps known in the field of re-refining used lubricants.

[0098] In particular, these treatment steps aim to eliminate, at least partially, water, solid particles, fuel and / or other contaminants, such as polycyclic aromatic hydrocarbons (PAHs), which are undesirable in the formulation of lubricants.

[0099] According to a particular embodiment, the regenerated lubricating oil used according to the invention comes from a used lubricant having been subjected to one or more prior steps of dehydration, distillation, filtration, hydrogenation, liquid / liquid extraction, decantation and / or passage of the used lubricant over an adsorbent material, preferably as detailed below.

[0100] Thus, the invention relates to the use, as a lubricating fluid, in particular for the lubrication of the components of a propulsion system of an electric vehicle, of a composition based on at least one at least partly re-refined lubricating oil, in particular formed from at least one at least partly re-refined lubricating oil, preferably as described above, said at least partly re-refined lubricating oil being obtained from a used lubricating composition having been subjected to at least one or more steps of dehydration, distillation, filtration, hydrogenation, liquid / liquid extraction, decantation and / or passage of said used lubricating composition over an adsorbent material, preferably carried out under the conditions detailed below.

[0101] Thus, the invention relates to the use, as a lubricating and cooling fluid, in particular for the lubrication and cooling of the components of a propulsion system of an electric vehicle, of a composition based on at least one at least partly re-refined lubricating oil, in particular formed from at least one at least partly re-refined lubricating oil, preferably as described above, said at least partly re-refined lubricating oil being obtained from a used lubricating composition having been subjected to at least one or more steps of dehydration, distillation, filtration, hydrogenation, liquid / liquid extraction, decantation and / or passage of said used lubricating composition over an adsorbent material, preferably carried out under the conditions detailed below.

[0102] Thus, the invention relates to the use, as a single fluid for the lubrication and cooling of the components of a propulsion system of an electric vehicle, of a composition based on at least one at least partly re-refined lubricating oil, in particular formed from at least one at least partly re-refined lubricating oil, preferably as described above, said at least partly re-refined lubricating oil being obtained from a used lubricating composition having been subjected to at least one or more steps of dehydration, distillation, filtration, hydrogenation, liquid / liquid extraction, decantation and / or passage of said used lubricating composition over an adsorbent material, preferably carried out under the conditions detailed below.

[0103] Preferably, the regenerated lubricating oil used according to the invention is obtained by subjecting a used lubricating composition to at least one dehydration step. This dehydration step makes it possible to eliminate any water possibly present in the used lubricant.

[0104] Advantageously, the regenerated lubricating oil used according to the invention thus comprises a water content of less than or equal to 10% by mass, in particular less than or equal to 5% by mass, in particular less than or equal to 2% by mass and more particularly less than or equal to 1% by mass, relative to the total mass of said regenerated lubricating oil.

[0105] This dehydration can be carried out by any method known to those skilled in the art, for example by distillation, evaporation, decantation, heating or passing a flow of hot air over the used lubricating composition.

[0106] According to one embodiment, the dehydration step can be carried out at a temperature between 50°C and 250°C, preferably between 100°C and 200°C. In particular, it can be carried out at a pressure between 50,000 and 150,000 Pa, preferably at atmospheric pressure.

[0107] Preferably, the regenerated lubricating oil used according to the invention is obtained by subjecting a used lubricating composition to at least one prior filtration step. This filtration can be carried out by any method known to those skilled in the art. This filtration step can be a particulate or non-particulate filtration step. It can, for example, be carried out by diatomaceous earth type systems.

[0108] Preferably, the regenerated lubricating oil used according to the invention is obtained by subjecting a used lubricating composition to at least one distillation step, preferably which follows a prior dehydration step. Said distillation step(s) may be carried out by any technique known to those skilled in the art. It may be, for example, atmospheric distillation or distillation under reduced pressure. The distillations may, for example, be carried out at a temperature of between 100°C and 500°C, preferably between 200°C and 400°C, more preferably between 300°C and 380°C. In particular, they can be operated at a pressure between 25 and 2,000 Pa, preferably between 50 and 1,000 Pa, more particularly between 50 and 250 Pa.

[0109] Advantageously, the regenerated lubricating oil used according to the invention is obtained by subjecting a used lubricating composition to at least one prior step of passing said used lubricating composition over an adsorbent material.

[0110] The adsorbent material advantageously makes it possible to selectively adsorb aromatic compounds, in particular PAHs.

[0111] In particular, passing over an adsorbent material, preferably over activated carbon, advantageously makes it possible to reduce the content of polycyclic aromatic hydrocarbons (PAHs), notably chosen from chrysene, benzo[b]fluoranthene, benzo[j]fluoranthene, benzo[k]fluoranthene, benzo[e]pyrene, benzo[a]pyrene, dibenz[a,h]anthracene and / or benz[a]anthracene, of the used lubricating composition.

[0112] The term “passage of the used lubricating composition over an adsorbent material” means the flow of the used lubricating composition over the adsorbent support.

[0113] The adsorbent materials may be, for example, activated carbon, zeolites, clays or functionalized porous compounds. Preferably, it is activated carbon.

[0114] For example, the regenerated lubricating oil used in the process of the invention can be obtained from the treatment of a used lubricating composition according to the process described in document WO 2018 / 109208.

[0115] In the case of passing the used lubricating composition over activated carbon, the quantity of activated carbon used is preferably between 0.5 and 60 g of activated carbon per liter of used lubricating composition, preferably between 0.5 and 50 g / L, preferably from 1 to 50 g / L, preferably between 1 and 30 g / L, for example between 5 and 60 g / L, preferably between 5 and 50 g / L.

[0116] The flow rate of the used lubricating composition may be between 1 m3 / h and 15 m3 / h, for example between 5 and 10 m3 / h.

[0117] Preferably, the activated carbon is characterized by a density of between 200 and 500 kg / m3, for example measured according to the ASTDM D2854 standard.

[0118] Preferably, the activated carbon is a coal, preferably comprising from 70 to 95%, advantageously from 80 to 90% by weight of carbon.

[0119] The step of passing the used lubricating composition onto an adsorbent support, preferably onto activated carbon, is advantageously preceded by the following preliminary steps: - one or more distillation stages; and - a filtration step, in particular as defined previously.

[0120] Advantageously, the regenerated lubricating oil used according to the invention can be obtained by subjecting a used lubricating composition to at least one prior hydrogenation (or hydrotreatment) step, preferably which follows a prior dehydration and / or distillation step. Said hydrogenation step(s) can be carried out by any technique known to those skilled in the art and generally consist of treating the lubricating oil with hydrogen, generally in the presence of a hydrotreatment catalyst. Such a catalyst can contain, for example, at least one oxide or a sulfide of at least one group VI metal and / or at least one group VIII metal, such as molybdenum, tungsten, nickel or cobalt, and a support, for example alumina, silica-alumina or a zeolite.

[0121] Advantageously, the regenerated lubricating oil used according to the invention can be obtained by subjecting a used lubricating composition to at least one prior step of liquid / liquid extraction by a solvent, preferably which follows a prior step of dehydration and / or distillation. In particular, the liquid / liquid extraction by a solvent advantageously makes it possible to lighten a dark-colored used oil, to eliminate at least in part the bad odor or the aromatic compounds, in particular the PAHs. Said extraction step(s) can be implemented by any technique known to those skilled in the art. The extraction is generally carried out in a mixer-settler or in an extraction column, using a suitable extraction solvent.

[0122] Advantageously, the regenerated lubricating oil used according to the invention can be obtained by subjecting a used lubricating composition to at least one prior decantation step. Said decantation step(s) can be implemented by any technique known to those skilled in the art.

[0123] It is understood that the invention is in no way limited to the use of regenerated oils obtained according to the treatment methods described above. Other lubricating oils at least partly re-refined, for example group I and / or II, resulting from treatment steps different from those described above, may be suitable for the invention.

[0124] In any event, a re-refined lubricating oil used according to the invention is distinguished from a used lubricating oil, in particular due to the reduced content of certain undesirable contaminating elements, for example water, fuel, metallic elements or even certain heteroatoms.

[0125] A regenerated lubricating oil used according to the invention is notably characterized by a silicon content of between 0 ppm and 300 ppm, notably between 1 and 300 ppm.

[0126] A regenerated lubricating oil used according to the invention is in particular characterized by a phosphorus content of less than or equal to 100 ppm, in particular between 0 ppm and 100 ppm, for example 0 ppm.

[0127] A regenerated lubricating oil used according to the invention may also be characterized by its content of one or more other elements chosen from chlorine, oxygen and nitrogen. It may, for example, have a chlorine content of between 0 ppm and 50 ppm, for example 0 ppm.

[0128] The content of these elements can be evaluated by any method known to those skilled in the art, for example by X-ray fluorescence (XRF), or by infrared or ultraviolet spectroscopy.

[0129] On the other hand, a regenerated lubricating oil used according to the invention is distinguished, due to its formation from a used lubricant, from a virgin or new base oil, oil directly derived from petroleum refining, or even from native base oils, for example of natural origin, both in terms of its composition and its physicochemical properties.

[0130] In particular, as indicated above, surprisingly, a regenerated lubricating oil has excellent thermo-physical and hydraulic properties, in particular in terms of viscosity index, density, Noack volatility, flash point and / or thermal conductivity, and advantageously thermo-physical and hydraulic properties superior to those of a virgin base oil.

[0131] Preferably, the kinematic viscosity measured at 100°C according to the ASTM D445 standard of the at least partly re-refined lubricating oil is greater than or equal to 3 mm2 / s, for example between 3 and 10 mm2 / s, more particularly between 3 and 8 mm2 / s.

[0132] Advantageously, the at least partly re-refined lubricating oil used according to the invention has a kinematic viscosity measured at 40°C according to the ASTM D445 standard of between 10 and 40 mm2 / s, in particular between 12 and 30 mm2 / s.

[0133] Preferably, an at least partly re-refined lubricating oil used according to the invention has a viscosity index greater than or equal to 110. The viscosity index of the at least partly re-refined lubricating oil can thus be between 110 and 130, in particular between 112 and 125.

[0134] The viscosity index can in particular be determined according to standard NF ISO 2909.

[0135] Preferably, a regenerated lubricating oil used according to the invention has a Noack volatility of less than or equal to 15%, or even strictly less than 12%. The Noack volatility of the at least partly re-refined lubricating oil can thus be between 8% and 15%, or even between 8% and 11.9%.

[0136] Noack volatility can in particular be determined according to the CEC L-40-93 standard at 250°C.

[0137] Preferably, a regenerated lubricating oil used according to the invention has a sulfur content of between 0.01% and 0.2% by mass, relative to the total mass of said regenerated lubricating oil.

[0138] Preferably, a regenerated lubricating oil used according to the invention has a content of aromatic compound(s) greater than or equal to 0.5% by mass, in particular greater than or equal to 1% by mass, relative to the total mass of said regenerated lubricating oil. The content of aromatic compound(s) in the regenerated lubricating oil may thus be between 1% and 25% by mass, in particular between 2.5% and 20% by mass, relative to the total mass of said regenerated lubricating oil.

[0139] The contents of these different elements can be determined according to any method known to those skilled in the art, for example by X-ray fluorescence (XRF) or by infrared or ultraviolet spectroscopy.

[0140] At least one re-refined lubricating oil used according to the invention advantageously has at least one, at least two, at least three, or even all of the following characteristics: - a kinematic viscosity measured at 100°C according to standard ASTM D445 greater than or equal to 2 mm2 / s, for example between 2 and 12 mm2 / s, more particularly between 3 and 10 mm2 / s; - a viscosity index greater than or equal to 100, in particular between 105 and 130, in particular between 105 and 125; - a Noack volatility less than or equal to 40%, in particular between 8% and 40%, more particularly between 10% and 38%; - a sulfur content of between 0.01% and 0.2% by mass, in particular between 0.015% and 0.1% by mass, relative to the total mass of said regenerated lubricating oil; - a content of aromatic compound(s) greater than or equal to 0.5% by mass, in particular between 1% and 25% by mass, relative to the total mass of said regenerated lubricating oil;

[0141] - a silicon content ranging from 2 to 60 ppm, preferably from 4 to 50 ppm by mass, relative to the total mass of said regenerated lubricating oil.

[0142] Advantageously, a regenerated lubricating oil used according to the invention has a density less than or equal to 870 kg / m3, in particular less than or equal to 860 kg / m3. The density of the at least partly re-refined lubricating oil can thus be between 830 and 870 kg / m3, in particular between 840 and 860 kg / m3.

[0143] The density can in particular be determined according to standard NF EN ISO 12185 at 15°C.

[0144] Advantageously, a regenerated lubricating oil used according to the invention has a flash point greater than or equal to 180°C, in particular greater than or equal to 182°C. The flash point of the at least partly re-refined lubricating oil can thus be between 182°C and 245°C.

[0145] The flash point can in particular be determined according to standard NF EN ISO 2592.

[0146] Advantageously, a regenerated lubricating oil used according to the invention has a thermal conductivity, measured at 40°C and at atmospheric pressure, greater than or equal to 115 mW / mK, in particular greater than or equal to 120 mW / mK. The thermal conductivity of the at least partly re-refined lubricating oil can thus be between 120 and 145 mW / mK, in particular between 125 and 145 mW / mK.

[0147] Thermal conductivity can in particular be determined according to the ASTM D7896-19 standard.

[0148] Due to these properties in terms of viscosity index, density, thermal conductivity, flash point, Noack volatility and density, the re-refined lubricating oils used according to the invention have excellent performance both in terms of mechanical durability, cooling efficiency and hydraulic performance, and advantageously increased performance compared to virgin base oils.

[0149] A high viscosity index makes it possible in particular to have a lubricating fluid whose viscosity varies little with temperature, thus ensuring good hydraulic properties of the lubricating fluid. Thus, the lubricating fluid according to the invention can be used in systems which may be subjected to large temperature variations, for example as a lubricating fluid, advantageously as a lubricating and cooling fluid, in vehicles, and remains pumpable over the temperature range in which it must circulate in said system.

[0150] In particular, re-refined lubricating oils advantageously have a low density, in particular lower than that of virgin base oils, and a high viscosity index, in particular higher than that of virgin base oils, which makes it possible to reduce pumping costs, while having better thermal properties. Lubricating fluid

[0151] As mentioned above, said re-refined lubricating oil(s) used according to the invention, in particular as defined and characterized above, can be used as such as a lubricating fluid, or be formulated in a composition intended to be used as a lubricating fluid.

[0152] As mentioned above, said re-refined lubricating oil(s) used according to the invention, in particular as defined and characterized above, can be used as such as lubricating and re-refining fluid. cooling, or be formulated in a composition intended for use as a lubricating and cooling fluid.

[0153] The composition used as a lubricating fluid, advantageously as a lubricating and cooling fluid, may thus comprise one or more base oils distinct from the at least partly re-refined lubricating oil and / or one or more additives.

[0154] In a particular embodiment, said re-refined lubricating oil(s) may be formulated in combination with one or more distinct base oils, in particular one or more new base oils.

[0155] They are in particular chosen from base oils conventionally used in the field of lubricants, such as mineral, synthetic or natural, animal or vegetable oils or their mixtures.

[0156] Advantageously, these base oils are oils of mineral or synthetic origin belonging to groups I to V according to the classes defined in the API classification (or their equivalents according to the ATIEL classification) and presented in table 1 above, or their mixtures.

[0157] A composition implemented according to the invention according to the invention may thus comprise, or even be formed from, a mixture of one or more lubricating oils at least partly re-refined and one or more new base oils, for example at least one mineral oil.

[0158] In particular, a composition used according to the invention may comprise between 0% and 80% by mass, in particular between 5% and 75% by mass of new base oil(s), distinct from re-refined lubricating oils required according to the invention and defined above, relative to the total mass of the composition.

[0159] According to a particular embodiment, a composition used as a lubricating fluid, advantageously as a lubricating and cooling fluid, according to the invention comprises less than 50% by mass of new base oil(s), distinct from re-refined lubricating oils, relative to the total mass of the composition.

[0160] Preferably, a composition used as a lubricating fluid according to the invention is formed mainly from said re-refined lubricating oil(s).

[0161] Thus, a composition used as a lubricating fluid according to the invention advantageously comprises more than 80% by mass, in particular between 90% and 100% by mass, of one or more lubricating oil(s) at least partly re-refined, relative to the total mass of the composition.

[0162] In a particular embodiment, a composition used as a lubricating fluid according to the invention is completely free of base oil other than re-refined lubricating oils.

[0163] According to a preferred embodiment of the invention, the composition used in as a lubricating fluid, and advantageously as a lubricating and cooling fluid, has a kinematic viscosity measured at 40°C ranging from 12 to 26 mm2 / s, preferably from 15 to 25 mm2 / s, more preferably from 20.5 to 24 mm2 / s, or even from 21 to 24 mm2 / s, typically measured according to standard ASTM D445.

[0164] The composition used as a lubricating fluid, and advantageously as a lubricating and cooling fluid, advantageously has at least one, at least two, or even all of the following characteristics: - a kinematic viscosity measured at 100°C typically measured according to the ASTM D445 standard greater than or equal to 2 mm2 / s, for example between 2 and 10 mm2 / s, more particularly between 3 and 8 mm2 / s; - a density at 15°C typically measured according to standard NF EN ISO 12185 less than or equal to 860 kg / m3, in particular between 830 and 860 kg / m3, in particular between 840 and 860 kg / m3; - a thermal conductivity, measured at 90°C and at atmospheric pressure, typically measured according to standard ASTM D7896-19, greater than or equal to 115 mW / mK, in particular between 115 and 140 mW / mK, in particular between 120 and 130 mW / mK.

[0165] According to a particular embodiment, the composition has:

[0166] - a kinematic viscosity typically measured according to ASTM D445 measured at 40°C ranging from 12 to 26 mm2 / s, in particular from 15 to 25 mm2 / s, and

[0167] - a thermal conductivity, measured at 90°C and at atmospheric pressure, ty stinging measured according to ASTM D7896-19, ranging from 115 to 140 mW / mK, in particular from 120 to 130 mW / mK.

[0168] According to a preferred embodiment of the invention, the composition used as a lubricating fluid, and advantageously as a lubricating and cooling fluid, comprises: - from 10 to 90% by weight, preferably from 20 to 80% by weight, more preferably from 30 to 70% by weight, of a first lubricating oil at least partly re-refined having a kinematic viscosity at 40°C ranging from 5 to 20 mm2 / s, preferably from 10 to 16 mm2 / s, typically measured according to the ASTM D445 standard, and - from 10 to 90% by weight, preferably from 20 to 80% by weight, more preferably from 30 to 70% by weight, of a second lubricating oil at least partly re-refined having a kinematic viscosity at 40°C ranging from 21 to 35 mm2 / s, preferably from 25 to 32 mm2 / s, typically measured according to the ASTM D445 standard,

[0169] relative to the total weight of the composition.

[0170] Preferably, according to this embodiment, the first lubricating oil at least in re-refined part having a kinematic viscosity at 40°C ranging from 5 to 20 mm2 / s, preferably from 10 to 16 mm2 / s has one or more of the following characteristics: - a kinematic viscosity at 100°C measured according to the ASTM D445 standard ranging from 2 to 6 mm2 / s, and / or - a viscosity index measured according to standard NF ISO 2909 ranging from 105 to 120, and / or - a flash point measured according to standard NF EN ISO 2592 ranging from 180°C to 210°C, and / or - a sulfur content ranging from 0.01 to 0.05% by weight, relative to the total weight of the at least partly re-refined lubricating oil, and / or - a Noack volatility measured according to the CEC L-40-93 standard at 250°C ranging from 15 to 40%.

[0171] Preferably, according to this embodiment using a mixture of two lubricating oils at least partly re-refined, the second lubricating oil at least partly re-refined having a kinematic viscosity at 40°C ranging from 21 to 35 mm2 / s, preferably from 25 to 32 mm2 / s, has one or more of the following characteristics: - a kinematic viscosity at 100°C measured according to the ASTM D445 standard ranging from 4 to 10 mm2 / s, and / or - a viscosity index measured according to standard NF ISO 2909 ranging from 110 to 130, and / or - a flash point measured according to standard NF EN ISO 2592 ranging from 210°C to 240°C, and / or - a sulfur content ranging from 0.02 to 0.2% by weight, relative to the total weight of the at least partly re-refined lubricating oil, and / or - a Noack volatility measured according to the CEC L-40-93 standard at 250°C ranging from 8 to 11.9%.

[0172] In a particular embodiment, a composition used as a lubricating fluid according to the invention may comprise, in addition to said re-refined lubricating oil(s), one or more additives, in particular intended to promote the compatibility of the lubricating fluid with the materials of the system for which it is intended.

[0173] These additives may in particular be chosen from anti-corrosion additives, friction modifier additives, extreme pressure additives, anti-wear additives, detergents, antioxidants, viscosity index (VI) improvers, pour point depressants (PPD), dispersants, anti-foaming agents, and mixtures thereof.

[0174] These additives can be added to the said regenerated base oil(s) put into work according to the invention or to the mixture of said regenerated base oil(s) and at least one new base oil in an appropriate quantity, determined by a person skilled in the art. It is understood that the nature and quantity of the additives used are chosen in such a way that the advantageous properties, as a lubricating fluid, of the composition based on said re-refined lubricating oil(s), are not or are not substantially altered by the envisaged addition.

[0175] A composition used as a lubricating fluid according to the invention may comprise between 0% and 20% by mass, in particular between 0.01% and 10% by mass, of additives, in particular as described above, relative to the total mass of the composition.

[0176] The invention thus relates, according to another of its aspects, to a process or method for preparing a lubricating fluid, comprising at least one step consisting of obtaining a lubricating oil at least partly re-refined from a used lubricant.

[0177] Advantageously, such a process or method comprises at least the steps consisting of: (i) having an at least partly re-refined lubricating oil obtained from a used lubricant, in particular formed by subjecting a used lubricant to at least one or more steps of dehydration, distillation, filtration, hydrogenation, liquid / liquid extraction, decantation and / or passing the used lubricant over an adsorbent material, preferably as detailed previously; (ii) optionally, mixing said at least partly re-refined lubricating oil with one or more new base oils, distinct from re-refined lubricating oils, for example one or more mineral oils; and (iii) optionally, supplementing said at least partly re-refined lubricating oil from step (i) or the mixture of lubricating oils from step (ii), with at least one additive, in particular as described above. Applications

[0178] As mentioned above, an at least partly re-refined lubricating oil is suitable for use as a lubricating fluid, given its durability properties, particularly for the lubrication of the components of a propulsion system of an electric or hybrid vehicle.

[0179] As mentioned above, the at least partly re-refined lubricating oil is also particularly suitable for use as a cooling fluid, given its thermo-physical properties.

[0180] In particular, a fluid based on at least one re-refined lubricating oil according to the invention can be used for various systems and applications, in particular as the sole fluid for the lubrication and cooling of the components of an electric vehicle propulsion system.

[0181] In particular, the present invention relates to the use of a composition based on at least one lubricating oil at least partly re-refined as a fluid for the lubrication of the components of a propulsion system of an electric vehicle.

[0182] Preferably, the composition based on at least one at least partly re-refined lubricating oil is used as a fluid for the lubrication and cooling of the components of a propulsion system of an electric vehicle.

[0183] More particularly, the composition based on at least one at least partly re-refined lubricating oil is used as the sole fluid for the lubrication of the geared motor and for the cooling of the battery of an electric vehicle.

[0184] The invention relates in particular to a method or process for lubricating, and preferably for lubricating and cooling, at least one member of a propulsion system of an electric or hybrid vehicle, preferably all of the members of a propulsion system of an electric vehicle, said method or process comprising at least one step of bringing into contact at said member, as lubricating fluid, advantageously lubricating and cooling fluid, a composition based on at least one lubricating oil that is at least partly re-refined, in particular as described above.

[0185] Such a process or method comprises in particular the steps consisting of: a) having a composition comprising, or even being formed from, one or more lubricating oil(s) at least partly re-refined, in particular as defined above; b) implementing said composition of step a) at the level of a component of a propulsion system of an electric or hybrid vehicle, in particular as described previously; and c) circulating said composition to provide lubrication and advantageously lubrication and cooling during operation of said propulsion system of an electric or hybrid vehicle.

[0186] For the purposes of the present invention, the term "propulsion system" is understood to mean a system comprising the mechanical parts necessary for propelling a vehicle. The propulsion system more particularly includes a motor, for example an electric motor comprising the rotor-stator assembly of the power electronics (dedicated to speed regulation), a transmission and possibly a battery. The battery itself is generally made up of a set of electrical accumulators, called cells.

[0187] Also, a lubricating fluid based on at least one re-refined lubricating oil according to the invention can further be used as a cooling fluid for cooling the battery present in an electric or hybrid vehicle.

[0188] As an example of application, a lubricating fluid according to the invention based on at least one re-refined lubricating oil can be used for the lubrication and cooling of a propulsion system of an electric or hybrid vehicle, and more particularly of the engine, the power electronics, the transmission and / or the battery.

[0189] A composition according to the invention based on at least one re-refined lubricating oil makes it possible to jointly achieve good properties in terms of cooling and lubrication of the parts in a propulsion system of an electric or hybrid vehicle, such as an electric motor of an electric or hybrid vehicle, as well as in terms of cooling the battery of an electric or hybrid vehicle.

[0190] The present invention also relates, according to another of its aspects, to a propulsion system for an electric or hybrid vehicle, in which a composition based on at least one at least partly re-refined lubricating oil, in particular as defined in the invention, is used as a lubricating fluid, preferably as a lubricating and cooling fluid, more preferably as a single fluid for the lubrication and cooling of all the components of a propulsion system of an electric vehicle.

[0191] According to the invention, the particular, advantageous or preferred characteristics of these oils and compositions make it possible to define uses according to the invention which are also particular, advantageous or preferred.

[0192] The invention will now be described by means of the following examples, given for illustrative and non-limiting purposes of the invention. Examples

[0193] Method for measuring kinematic viscosity

[0194] The kinematic viscosity of oils is measured at 40°C (KV40) and at 100°C (KV100) using a viscometer, according to the NF EN ISO 3104 standard. This standard is technically equivalent to the ASTM D445 standard. The results are expressed in mm2 / s (equivalent to the centistoke, noted cSt).

[0195] Method of measuring volatility

[0196] Volatility is used to determine the evaporation loss of oils at high temperatures. It is determined by the NOACK volatility test, carried out according to CEC L-40-93. During the test, the oil sample is subjected to a constant flow of air, heated to approximately 250°C, for approximately 60 minutes. The result is expressed as a fraction of weight loss, as a mass percentage.

[0197] Method for measuring density

[0198] The density of oils is measured at 15°C using a U-tube densimeter, according to standard NF EN ISO 12185. It is expressed in kg / m3.

[0199] Method for measuring viscosity index

[0200] The viscosity index is a dimensionless ratio, which gives an indication of the variation in the viscosity of oils as a function of temperature. This is calculated from the kinematic viscosity values ​​at 40°C and 100°C, according to the NF ISO 2909 standard. The higher this index, the less the viscosity of the oils is influenced by temperature variations.

[0201] Method for measuring thermal conductivity

[0202] Thermal conductivity, often denoted X (lambda), characterizes the ability of the oil to diffuse heat in the media. It is measured by a transient hot wire liquid thermal conductivity method, according to ASTM D7896-19. It is expressed in mW / mK.

[0203] Method for measuring heat capacity

[0204] The heat capacity (Cp) of a sample corresponds to the quantity of energy, in the form of heat, that must be supplied to it or that it must lose to obtain a variation in its temperature of one degree. It was determined according to the ASTM El269 standard at different temperatures, from 0 to 90°C. It is expressed in J / (g*K).

[0205] Flash point measurement method

[0206] The flash point gives an indication of the ability of a product to form a flammable mixture with air under controlled conditions. It is determined using a Cleveland open-cup apparatus, according to standard NF EN ISO 2592. The flash point at ambient atmospheric pressure is the lowest temperature at which the passage of a flame over the test vessel containing the oil causes the vapors above the surface of the liquid to ignite. It is expressed in degrees Celsius.

[0207] Method for measuring the content of sulfur and aromatic compounds

[0208] The sulfur and aromatic compound contents in the oil are determined by infrared or ultraviolet spectroscopy.

[0209] Measurement of gear deterioration by seizure

[0210] The galling load capacity indicates the maximum load that the lubricant can withstand without damaging the gear tooth surface. It is determined according to ISO 14635-1 (test method FZG A / 8.3 / 90). Example 1

[0211] The properties of two re-refined lubricating oils II and 12, in accordance with the invention and commercially available, were evaluated.

[0212] These oils are obtained from used base oils and having undergone at least one stage of dehydration, distillation, filtration, hydrogenation, extraction liquid / liquid, decantation and / or passage of the used lubricant over an adsorbent material, in particular at least one step of dehydration, distillation, liquid / liquid extraction and / or hydrogenation.

[0213] A new lubricating oil Cl, not in accordance with the invention because it had not undergone any recycling or re-refining step, was also evaluated.

[0214] This oil is a monoester type base oil.

[0215] In particular, the kinematic viscosities at 40°C and 100°C, viscosity index, density, volatility, flash point and thermal conductivity of these oils were measured according to the protocols detailed above.

[0216] The results are presented in Table 2 for re-refined and virgin oils.

[0217] [Tables2] Oil II 12 Cl KV40 (mm2 / s) 13.91 28.2 4.65 KV100 (mm2 / s) 3.319 5.6 1.66 Viscosity index 109 120 137 Density (kg / m3) 843.8 849.5 858.3 Noack volatility (%) 32.8 10.9 -100 Flash point (°C) 182 230 146 Thermal conductivity 40°C (mW / mK) 131.99 142.09 109 Sulphur content (%) 27 0.02 0 Aromatic content (%) nd 9 0

[0218] nd not determined

[0219] These oils II, 12 and Cl are formulated. The formulated compositions are described in Table 3. In Table 3: - ADD1 is an additive package comprising at least one phosphorus anti-wear agent and at least one antifoam agent. - ADD2 is an antioxidant. - ADD3 is a pour point depressant. - ADD4 is a viscosity agent polymer.

[0220] [Tables3] Compositions Yarn FC1 FC2 FC3 Il (%) 55.7 12 (%) 35.75 Cl (%) 99.5 91.95 85.25 ADD1 (%) 8.05 8.05 8.05 ADD2 (%) 0.5 ADD3 (%) 0.5 ADD4 (%) 6.7

[0221] These compositions were evaluated for their mechanical durability properties, their physicochemical properties as well as their cooling properties. The results are shown in Table 4.

[0222] [Tables4] Temperature (°C) Wire FC1 FC2 FC3 KV40 (mm2 / s) 40 21.8 4.6 5.584 13.76 KV100 (mm2 / s) 100 4.6 1.7 1.958 4.558 Density (g / cm3) 15 0.85 0.86 0.86 0.86 Thermal conductivity (mW / mK) 30 135 110 110 110 40 133 109 109 109 50 132 107 107 107 60 131 106 106 106 70 129 104 104 104 80 128 102 102 102 90 126 101 101 101 Load capacity at seizure (-) 12 5 12 11 Results

[0223] The results in Table 4 show that the composition according to the invention (Fil) comprising a mixture of two at least partly re-refined oils exhibits both good mechanical durability properties (seizure load capacity) and good cooling properties (thermal conductivity).

[0224] Consequently, the at least partly re-refined oils have particularly advantageous mechanical durability properties and thermo-physical properties, making it possible to achieve performances as lubricating and cooling fluids that are identical or even superior to those of new lubricating oils that have not undergone any recycling.

[0225] A lower density also makes it possible to ensure good hydraulic performance, in particular to reduce the costs associated with pumping these oils during their use as a lubricating and cooling fluid.

[0226] In conclusion, a lubricating oil that is at least partly re-refined has particularly advantageous properties, in particular identical or even superior to those of a new oil, allowing its use as a lubricating fluid and cooling fluid.

Claims

Claims

1. Use of a composition comprising at least one lubricating oil at least partly re-refined as a lubricating fluid for the lubrication of the components of a propulsion system of an electric or hybrid vehicle.

2. Use according to the preceding claim, in which the composition is used as a lubricating fluid for the geared motor and as a cooling fluid for the battery.

3. Use according to any one of the preceding claims, in which the composition is used as the sole fluid for the lubrication and cooling of all the components of a propulsion system of an electric vehicle.

4. Use according to any one of the preceding claims, wherein the composition allows to improve the mechanical durability properties, preferably both the mechanical durability properties and the cooling properties.

5. Use according to any one of the preceding claims, in which the at least partly re-refined lubricating oil comes from a used lubricant having been subjected to one or more prior steps of dehydration, distillation, filtration, hydrogenation, liquid / liquid extraction, decantation and / or passage of the used lubricant over an adsorbent material.

6. Use according to any one of the preceding claims, in which the composition has a kinematic viscosity measured at 40°C ranging from 12 to 26 mm2 / s, preferably from 15 to 25 mm2 / s, more preferably from 20.5 to 24 mm2 / s, or even from 21 to 24 mm2 / s.

7. Use according to any one of the preceding claims, in which the composition comprises: - from 10 to 90% by weight, preferably from 20 to 80% by weight, more preferably from 30 to 70% by weight, of a first lubricating oil at least partly re-refined having a kinematic viscosity at 40°C ranging from 5 to 20 mm2 / s, preferably from 10 to 16 mm2 / s, and - from 10 to 90% by weight, preferably from 20 to 80% by weight, more preferably from 30 to 70% by weight, of a second lubricating oil at least partly re-refined having a kinematic viscosity at 40°C ranging from 21 to 35 mm2 / s, preferably 25 to 32 mm2 / s, relative to the total weight of the composition.

8. Use according to any one of the preceding claims, in which the composition has: - a kinematic viscosity measured at 40°C ranging from 12 to 26 mm2 / s, in particular from 15 to 25 mm2 / s, and - a thermal conductivity, measured at 90°C and at atmospheric pressure, ranging from 115 to 140 mW / mK, in particular from 120 to 130 mW / mK.

9. Use according to any one of the preceding claims, in which the composition has a sulfur content of between 0.01% and 0.2% by mass, relative to the total mass of said at least partly re-refined lubricating oil.

10. Use according to any one of the preceding claims, in which the composition has a content of aromatic compound(s) greater than or equal to 0.5% by mass, in particular greater than or equal to 1% by mass, in particular between 1% and 25% by mass, more particularly between 2.5% and 20% by mass, relative to the total mass of said at least partly re-refined lubricating oil.

11. Use according to any one of the preceding claims, in which the composition has a density less than or equal to 870 kg / m3, in particular between 830 and 870 kg / m3, more particularly between 840 and 860 kg / m3.

12. Use according to any one of the preceding claims, in which the composition has a thermal conductivity, measured at 90°C and at atmospheric pressure, greater than or equal to 115 mW / mK, more particularly between 115 and 140 mW / mK.

13. Use according to any one of the preceding claims, wherein said composition comprises one or more base oils distinct from the at least partly re-refined lubricating oil and / or one or more additives, in particular chosen from anti-corrosion additives, friction modifier additives, extreme pressure additives, anti-wear additives, detergents, antioxidants, agents viscosity index (VI) improvers, pour point depressants (PPD), dispersants, antifoam agents, and mixtures thereof.

14. Use according to any one of the preceding claims, wherein said composition comprises more than 80% by mass, in particular between 90% and 100% by mass of one or more lubricating oils at least partly re-refined, relative to the total mass of said composition.

15. Method for lubricating, preferably for lubricating and cooling, the components of a propulsion system of an electric vehicle, comprising at least one step of bringing into contact at the level of said system a composition based on at least one at least partly re-refined lubricating oil, in particular as defined in any one of claims 5 to 14.