Re-refined lubricating oils for improving the energy saving properties of drive systems

Abstract

The present application relates to the use of at least one lubricating oil, which is at least partially re-refined, for improving the energy efficiency properties of a lubricating composition intended for a drive system. The application also relates to the use of a lubricating composition based on at least one lubricating oil, which is at least partially re-refined, for reducing the energy consumption of a drive system lubricated with said composition, in particular in a vehicle.

Description

[0001] Description

[0002] Title: Re-refined lubricating oils to improve the energy-saving properties of powertrain systems

[0003] Technical field

[0004] The present invention relates to the field of lubricating compositions, more particularly the field of lubricating compositions used for the lubrication of moving parts in stationary or mobile motorization systems, in particular in vehicles.

[0005] It relates more particularly to the use of re-refined lubricating oils in lubricating compositions intended for the lubrication of engine systems in order to improve their properties in terms of energy efficiency, in other words their ability to ultimately limit the energy consumption of the engine system.

[0006] Prior art

[0007] Lubricating compositions, also called "lubricants", are commonly used in the various components of motor vehicles for the main purpose of reducing friction forces between the various moving metal parts in these components, in particular the engine, the transmission and the hydraulic circuit. They are also effective in preventing premature wear or even damage to these parts, and in particular to their surface. To do this, a lubricating composition is conventionally composed of a base oil to which are generally associated several additives dedicated to boosting the lubricating performance of the base oil, such as for example friction modifying additives, but also to provide additional performance.

[0008] Combustion engines generate CO2 during operation due to the combustion of the fuel they use to operate. Current environmental concerns, particularly with regard to reducing carbon dioxide emissions, have led to an urgent need to reduce the fuel consumption of motor vehicles.

[0009] In this respect, lubricants represent an effective means of influencing fuel consumption through their impact on the friction forces generated between the various components of engine systems, for example in motor vehicles. Lubricants with good traction or friction performance advantageously allow a reduction in friction in hydrodynamic lubrication regimes and, consequently, a reduction in fuel consumption.

[0010] Thus, the formulation of lubricants with good traction or friction performance represents an important issue insofar as it constitutes an important lever in reducing fuel consumption, and therefore in reducing carbon dioxide emissions and, more generally, in reducing the energy consumption of engine systems.

[0011] Summary of the invention

[0012] The present invention aims specifically to propose new lubricating compositions intended for the lubrication of engine systems, in particular in vehicles, making it possible to achieve improved performance in terms of energy saving, for example in terms of fuel saving.

[0013] Surprisingly, as the following examples show, the inventors have discovered that re-refined oils from used oil recycling channels provide access to lubricants with improved properties in terms of energy efficiency, in particular by reducing the traction coefficient.

[0014] It is indeed well known to those skilled in the art, in particular from the article Holmberg et al. (Kenneth Holmberg, Peter Andersson, Ali Erdemir, Global energy consumption due to friction in passenger cars, Tribology International, Volume 47, 2012, Pages 221-234, ISSN 0301-679X), that there is a direct correlation between the reduction of the traction coefficient and energy efficiency.

[0015] Thus, the invention relates, according to a first of its aspects, to the use of at least one lubricating oil at least partly re-refined to improve the energy efficiency properties of a lubricating composition intended for a motorization system.

[0016] According to another of its aspects, the invention relates to the use of at least one at least partly re-refined lubricating oil to improve the energy efficiency properties of a lubricating composition intended for a motorization system; 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.

[0017] 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 in part from a used lubricating composition having been subjected to one or more treatment steps known as re-refining treatment.

[0018] 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.

[0019] 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".

[0020] Due to their origin, used lubricating oils, particularly engine lubricating oils, contain 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. 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.

[0021] Methods for re-refining or reconditioning used lubricating oils have been developed to regenerate these oils and enable their subsequent reuse.

[0022] 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. Preferably, as detailed in the rest of the text, the at least partly re-refined lubricating oils used according to the invention have characteristics, in particular in terms of saturated compound contents, sulfur content and viscosity index, satisfying the criteria defined by the API classification for group I or group II oils.

[0023] The at least partly re-refined lubricating oils used according to the invention preferably have a kinematic viscosity measured at 100°C according to standard ASTM D445 greater than or equal to 4.0 mm 2 / s, in particular between 4.0 and 12 mm 2 / s, in particular greater than or equal to 4.3 mm 2 / s and more particularly between 4.4 and 10 mm 2 / s, especially between 4.5 and 6 mm 2 / s.

[0024] To the inventors' knowledge, it has never been proposed to use a recycled lubricating oil in a lubricating composition intended for a motorization system, to improve its performance in terms of energy efficiency.

[0025] “Energy efficiency” means the ability of a lubricating composition to ultimately limit the energy consumption of a mobile or stationary, combustion, hybrid or electric motor system, in particular, but not limited to, by reducing the coefficient of traction or friction, more particularly at the level of the engine itself, but also of the transmission components, such as the reducer, the gear(s), the axles, the bearings. This energy efficiency results in a gain in fuel consumption for a combustion engine (“Fuel Economy” or FE) or by a service life or an extended recharge interval for an electric motor.

[0026] The invention also relates to a process or method for improving the energy efficiency, for example the Fuel-Eco properties, of a lubricant intended for an engine system, by using in the formulation of the lubricant one or more at least partly re-refined base oils.

[0027] In a particular embodiment, the invention relates to the use of at least one at least partially re-refined lubricating oil in a lubricating composition intended for a powertrain system equipped with an internal combustion engine, to improve its Fuel-Eco properties. As detailed in the remainder of the text, the re-refined lubricating oils can thus be used to improve the “Energy Efficiency” properties of lubricants for various powertrain systems, in particular in vehicles, including light vehicles, combustion engine vehicles, electric or hybrid vehicles; heavy-duty vehicles, or even marine vehicles.

[0028] Preferably, said re-refined lubricating oil(s) may represent more than 50% by mass, in particular more than 70% by mass, in particular more than 80% by mass and more particularly more than 90% by mass, of the total mass of the lubricating composition.

[0029] As detailed in the remainder of the text, said re-refined lubricating oil(s) may be used as the sole base oil(s), i.e., without the addition of a separate base oil, e.g., new base oil. Alternatively, they may be used in combination with at least one new base oil.

[0030] In a particular embodiment, the lubricating composition is formed solely from one or more re-refined lubricating oils.

[0031] Advantageously, the use of one or more re-refined lubricating oils makes it possible to improve the energy efficiency of the lubricating compositions by reducing their traction coefficient.

[0032] Thus, said at least partially re-refined lubricating oil(s) are notably used according to the invention to reduce the traction coefficient of the lubricating composition.

[0033] This traction coefficient, noted COT, can be measured using an MTM tribometer, for example under the conditions detailed in the examples.

[0034] Surprisingly, as illustrated in the examples, the inventors have discovered that recycled oils have reduced traction coefficients, compared to new oils, which makes them particularly advantageous for improving the energy efficiency of lubricants. In fact, a lower traction coefficient makes it possible to effectively reduce friction losses in mechanical contacts, and thus to reduce the energy consumption of the engine, for example the fuel consumption of an internal combustion engine. Advantageously, re-refined oils allow a reduction in the traction coefficient over a wide temperature range, corresponding to the temperatures encountered in engines, in particular for temperatures ranging from 40°C to 100°C.

[0035] The invention also relates to the use of an at least partially re-refined lubricating oil to reduce the traction coefficient of a lubricating composition intended for the lubrication of a motorization system.

[0036] It also relates to a process or method for reducing the traction coefficient of a lubricant intended for the lubrication of an engine system, by using in the formulation of the lubricant one or more base oils which are at least partly re-refined.

[0037] The invention also relates, according to another of its aspects, to the use of a lubricating composition based on at least one at least partly re-refined lubricating oil, for reducing energy consumption or improving the energy-saving properties of a powertrain system lubricated using said lubricating composition, for example fuel consumption in the context of a combustion powertrain system.

[0038] As detailed in the rest of the text, said motorization system may in particular be a mobile or stationary, combustion, electric or hybrid motorization system, in particular in a vehicle, in particular in a light vehicle, heavy goods vehicle or marine vehicle.

[0039] The invention further relates to a method or process for reducing energy consumption or for improving the energy saving properties of a powertrain system, in particular in a vehicle, comprising lubricating at least one of the parts of the powertrain system with a lubricating composition comprising at least one at least partly re-refined oil.

[0040] The process or method for reducing the energy consumption of a motorization system may more particularly comprise the steps consisting of:

[0041] (i) preparing an at least partly re-refined lubricating oil from a used lubricant;

[0042] (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;

[0043] (iii) supplementing said at least partly re-refined lubricating oil from step (i), or the mixture of lubricating oils from step (ii), with one or more additives, for example as described in the remainder of the text; and

[0044] (iv) using the lubricant obtained at the end of step (iii) for the lubrication of at least one mechanical part of said motorization system

[0045] Also, advantageously, as illustrated in the examples that follow, reclaimed lubricating oils exhibit reduced Noack volatility compared to that of a virgin base oil.

[0046] Thus, said at least partially re-refined lubricating oil(s) are notably used according to the invention to reduce the Noack volatility of the lubricating composition.

[0047] Noack volatility can be determined in particular according to the CEC L-40-93 standard.

[0048] Lower volatility advantageously allows the use of more fluid base oils to be considered in the formulation of lubricants, this further enabling action to be taken to improve the energy efficiency of the composition, for example, in the case of a composition intended for a combustion engine system, to maximize Fuel-Eco gains.

[0049] The invention also relates to the use of an at least partially re-refined lubricating oil to reduce the volatility of a lubricating composition intended for the lubrication of a motorization system.

[0050] It also relates to a process or method for reducing the volatility of a lubricant intended for the lubrication of an engine system, by using in the formulation of the lubricant one or more base oils that are at least partly re-refined.

[0051] Advantageously, the use of re-refined lubricating oils according to the invention thus makes it possible to meet current expectations for reducing environmental impact and conserving resources via two levers: on the one hand, the formulation of lubricants based on regenerated lubricating oils makes it possible to reduce the carbon footprint of the products, compared to the use of virgin base oils and, on the other hand, as described previously, the use of re-refined base oils makes it possible to improve the energy efficiency of the lubricating compositions, in particular by reducing the traction coefficient, and in particular to act on the reduction of the fuel consumption of combustion engine systems and therefore on CO2 emissions.

[0052] Other characteristics, variants and advantages of the use of lubricating oils at least partly re-refined according to the invention will become more apparent on reading the description and examples which follow, given by way of illustration and not limitation of the invention.

[0053] In the rest of the text, the expressions "between ... and ...", "ranging ... to ..." and "varying from ... to ..." are equivalent and are intended to mean that the limits are included, unless otherwise stated.

[0054] In the description and examples, unless otherwise indicated, percentages are percentages by mass. The percentages are therefore expressed by mass relative to the total mass of the composition.

[0055] Detailed description

[0056] Lubricating oil at least partly re-refined

[0057] As previously specified, the base oil used to improve the energy efficiency properties of the lubricating compositions is a lubricating oil that is at least partly re-refined, also known as “regenerated oil” or “recycled oil”, in other words a lubricating oil derived from a used lubricating composition that has been subjected to one or more re-refining treatment steps.

[0058] 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.

[0059] 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.

[0060] It may be a mixture of several base oils, for example a mixture of two, three, or four base oils. 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.

[0061] 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.

[0062] [Table 1]

[0063] 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).

[0064] 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.

[0065] 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.

[0066] A used lubricating composition, from which the reclaimed lubricating oil used according to the invention is derived, may contain various conventional additives in the field of lubricants, such as friction modifier 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.

[0067] As already mentioned above, 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.

[0068] 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.

[0069] The composition of used lubricant can of course vary depending on the origin of the lubricant, its initial formulation and the fact that it may have been contaminated differently depending on its use.

[0070] The regenerated lubricating oil used according to the invention comes more particularly from a used lubricant having been subjected to one or more prior pre-treatment steps known in the field of re-refining used lubricants.

[0071] In particular, these treatment steps aim to remove, 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.

[0072] 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.

[0073] 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.

[0074] 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.

[0075] 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.

[0076] 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.

[0077] 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. 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 following a prior dehydration step. Said distillation step(s) can be carried out by any technique known to those skilled in the art. It can, for example, be atmospheric distillation or distillation under reduced pressure.The distillations can be carried out, for example, 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 carried out at a pressure of between 25 and 2,000 Pa, preferably between 50 and 1,000 Pa, more particularly between 50 and 250 Pa.

[0078] 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.

[0079] The adsorbent material advantageously allows the selective adsorption of aromatic compounds, in particular PAHs.

[0080] 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.

[0081] The term "passage of the used lubricating composition over an adsorbent material" means the flow of the used lubricating composition over the adsorbent support.

[0082] Absorbent materials may be, for example, activated carbon, zeolites, clays or functionalized porous compounds. Preferably, it is activated carbon.

[0083] For example, the regenerated lubricating oil used in the method of the invention can be obtained from the treatment of a used lubricating composition according to the method described in document WO 2018 / 109208.

[0084] 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. The flow rate of passage of the used lubricating composition may be between 1 m 3 / h and 15 m 3 / h, for example between 5 and 10 m 3 / h.

[0085] Preferably, the activated carbon is characterized by a density between 200 and 500 kg / m 3 , for example measured according to ASTDM D2854.

[0086] Preferably, the activated carbon is a coal, preferably comprising from 70 to 95%, advantageously from 80 to 90% by weight of carbon.

[0087] The step of passing the used lubricating composition onto an adsorbent support, preferably onto activated carbon, is advantageously preceded by the following preliminary steps:

[0088] - one or more distillation stages; and

[0089] - a filtration step, in particular as defined previously.

[0090] 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 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.

[0091] 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. 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 decantation.Said decantation step(s) may be implemented by any technique known to those skilled in the art.

[0092] 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, resulting from treatment steps different from those described above, may be suitable for the invention.

[0093] 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.

[0094] 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.

[0095] 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.

[0096] 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.

[0097] 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. The content of these elements may 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.

[0098] Preferably, the re-refined lubricating oils used according to the invention have characteristics, in particular 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.

[0099] According to a particularly preferred embodiment, said re-refined lubricating oil(s) used according to the invention are chosen from re-refined oils whose characteristics, in particular in terms of saturated compound content, sulfur content and viscosity index, satisfy the criteria defined by the API classification for group I oils or group II oils.

[0100] Preferably, the re-refined lubricating oils used according to the invention, in particular whose characteristics are equivalent to those defined by the API classification for group I or group II base oils, have a kinematic viscosity measured at 100°C according to the ASTM D445 standard, between 4.0 and 12 mm 2 . s 1 .

[0101] Advantageously, the re-refined lubricating oil used according to the invention has a kinematic viscosity measured at 100°C according to standard ASTM D445, greater than or equal to 4.3 mm 2 . s 1 , in particular between 4.4 and 10 mm 2 . s 1 and more particularly between 4.5 and 6 mm 2 . s -1 .

[0102] Preferably, a re-refined lubricating oil used according to the invention, in particular whose characteristics are equivalent to those defined by the API classification for group I or group II base oils, has a viscosity index greater than or equal to 110. The viscosity index of the at least partly re-refined lubricating oil may be more particularly between 110 and 130, in particular between 112 and 125 and more particularly between 112 and 122.

[0103] The viscosity index can in particular be determined according to standard NF ISO 2909. Preferably, a regenerated lubricating oil used according to the invention, in particular whose characteristics are equivalent to those defined by the API classification for group I or group II base oils, has a sulfur content of between 0.01% and 0.2% by mass, relative to the total mass of said regenerated lubricating oil.

[0104] Preferably, a regenerated lubricating oil used according to the invention, in particular whose characteristics are equivalent to those defined by the API classification for group I or group II base oils, 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 in particular 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.

[0105] The contents of these different elements can be determined using any method known to those skilled in the art, for example by X-ray fluorescence (XRF) or by infrared or ultraviolet spectroscopy.

[0106] In a first embodiment variant, the re-refined lubricating oil used according to the invention has characteristics, in particular in terms of saturated compound content, sulfur content and viscosity index, satisfying the criteria defined by the API classification for group I oils.

[0107] Such a regenerated oil, whose characteristics are equivalent to those of group I base oils, advantageously has a kinematic viscosity measured at 100°C according to standard ASTM D445, greater than or equal to 4.4 mm 2 / s, in particular between 4.5 and 10 mm 2 / s and more particularly between 4.5 and 6 mm 2 / s.

[0108] In particular, it has a viscosity index greater than or equal to 110, in particular between 110 and 130, in particular between 112 and 125 and more particularly between 112 and 122.

[0109] The viscosity index can in particular be determined according to standard NF ISO 2909.

[0110] Preferably, a regenerated lubricating oil used according to the invention has a sulfur content greater than 0.03% by mass, in particular between 0.05 and 0.20% by mass. Preferably, a regenerated lubricating oil used according to the invention has a content of aromatic compound(s) greater than or equal to 5% by mass, in particular between 5% and 15%, in particular between 7% and 20%, relative to the total mass of said regenerated lubricating oil.

[0111] In another particular embodiment variant, the re-refined lubricating oil used according to the invention has characteristics, in particular in terms of saturated compound content, sulfur content and viscosity index, satisfying the criteria defined by the API classification for group II oils.

[0112] Such a regenerated oil, whose characteristics are equivalent to those of group II base oils, advantageously has a kinematic viscosity measured at 100°C according to standard ASTM D445, greater than or equal to 4.0 mm 2 / s, in particular between 4.2 and 10 mm 2 / s, more particularly between 4.3 and 6 mm 2 / s.

[0113] In particular, it has a viscosity index greater than or equal to 110, in particular between 110 and 130, in particular between 112 and 125 and more particularly between 115 and 120.

[0114] The viscosity index can in particular be determined according to standard NF ISO 2909.

[0115] Preferably, a regenerated lubricating oil used according to the invention has a sulfur content of less than or equal to 0.03% by mass, in particular less than or equal to 0.02% by mass.

[0116] Preferably, a regenerated lubricating oil used according to the invention has a content of aromatic compound(s) less than or equal to 10% by mass, in particular less than or equal to 9% by mass, and more particularly between 1 and 9% by mass, relative to the total mass of said regenerated lubricating oil.

[0117] As indicated above, the re-refined lubricating oils used according to the invention, in particular whose characteristics are equivalent to those defined by the API classification for group I or group II base oils, advantageously have, compared to virgin base oils of equivalent group according to the API classification, reduced volatility.

[0118] The volatility properties can be more particularly evaluated by determining the Noack volatility according to the CEC L-40-93 standard. Advantageously, a regenerated lubricating oil used according to the invention has a Noack volatility of less than or equal to 15%, in particular less than or equal to 14%. More preferably, a regenerated lubricating oil used according to the invention may have a Noack volatility strictly less than 12%, in particular between 7% and 11%.

[0119] Also, as mentioned above, the re-refined base oils used according to the invention advantageously have lower traction coefficients compared to virgin base oils, and this advantageously over a wide temperature range.

[0120] The traction coefficient can be determined by MTM machine (Mini Traction Machine) sold by PCS instrument. It can be evaluated, as described in the examples, according to the following operating conditions: temperature of 40°C or 100°C, load of 25N, sliding rate SRR (sliding-rolling ratio) of 40% and speed gradient of 2500 to 20 mm / s.

[0121] In particular, the traction coefficient of a re-refined base oil, the characteristics of which are equivalent to those defined by the API classification for Group I or Group II base oils, is thus significantly reduced compared to the traction coefficient of a virgin base oil of an equivalent group according to the API classification.

[0122] Advantageously, the coefficient of traction (COT) of the re-refined lubricating oils used according to the invention, in particular whose characteristics are equivalent to those defined by the API classification for group I or group II base oils, is reduced by at least 7%, in particular by at least 10%, advantageously by at least 15%, in particular by at least 20%, or even by at least 25%, compared to the coefficient of traction of a virgin base oil of equivalent group according to the API classification.

[0123] In particular, a re-refined base oil used according to the invention, the characteristics of which are equivalent to those defined by the API classification for group I base oils, advantageously has a lower traction coefficient than that of a virgin group I base oil. Advantageously, the TOC traction coefficient of a re-refined oil, the characteristics of which are equivalent to those defined by the API classification for group I base oils, evaluated at a temperature of 40°C, is less than or equal to 0.050, preferably less than or equal to 0.048 and more preferably less than or equal to 0.045.

[0124] Advantageously, the TOC traction coefficient of a re-refined oil, the characteristics of which are equivalent to those defined by the API classification for group I base oils, evaluated at a temperature of 100°C, is less than or equal to 0.026, preferably less than or equal to 0.025 and more preferably less than or equal to 0.024.

[0125] Similarly, a re-refined base oil whose characteristics are equivalent to those defined by the API classification for Group II base oils, advantageously has a lower traction coefficient than that of a virgin Group II base oil.

[0126] Advantageously, the TOC traction coefficient of a re-refined oil, the characteristics of which are equivalent to those defined by the API classification for group II base oils, evaluated at a temperature of 40°C, is less than or equal to 0.045, preferably less than or equal to 0.043.

[0127] Advantageously, the TOC traction coefficient of a re-refined oil, the characteristics of which are equivalent to those defined by the API classification for group II base oils, evaluated at a temperature of 100°C, is less than or equal to 0.022, preferably less than or equal to 0.020.

[0128] Advantageously, these good traction coefficient reduction properties are verified over a wide range of lubricant operating temperatures, in particular for temperatures ranging from 40°C to 100°C, representative of the temperatures at the engine system level.

[0129] According to a particular embodiment, a regenerated lubricating oil used according to the invention has a density less than or equal to 870 kg / m 3 , in particular less than or equal to 860 kg / m 3The density of the at least partly re-refined lubricating oil can thus be between 830 and 870 kg / m 3 , particularly between 840 and 860 kg / m 3 . The density can in particular be determined according to standard NF EN ISO 12185.

[0130] In particular, a regenerated lubricating oil used according to the invention has a flash point greater than or equal to 225°C, in particular greater than or equal to 228°C. The flash point of the at least partly re-refined lubricating oil can thus be between 225°C and 245°C.

[0131] The flash point can in particular be determined according to standard NF EN ISO 2592.

[0132] In particular, a regenerated lubricating oil used according to the invention has a thermal conductivity, measured at 100°C and at atmospheric pressure, greater than or equal to 125 mW / mK, in particular greater than or equal to 128 mW / mK. The thermal conductivity of the at least partly re-refined lubricating oil can thus be between 125 and 145 mW / mK, in particular between 128 and 140 mW / mK.

[0133] Thermal conductivity can be determined in particular according to ASTM D7896-19.

[0134] LUBRICATING COMPOSITION

[0135] Said re-refined lubricating oil(s) may be used as the sole base oil(s) of the lubricating composition, or may be formulated in combination with one or more separate base oils, in particular one or more new base oils.

[0136] These new base oils are particularly chosen from base oils conventionally used in the field of lubricants, such as mineral, synthetic or natural, animal or vegetable oils or their mixtures.

[0137] 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.

[0138] A lubricating composition implemented according to the invention may thus comprise a mixture of one or more at least partly re-refined lubricating oils and one or more new base oils, for example at least one mineral oil.

[0139] Preferably, a lubricating composition according to the invention comprises less than 50% by mass of new base oil(s), distinct from re-refined lubricating oils. Preferably, a lubricating composition according to the invention is formed mainly from said re-refined lubricating oil(s).

[0140] In particular, said re-refined lubricating oil(s) may represent more than 70% by mass of the total mass of the lubricating composition, in particular more than 80% by mass, in particular more than 90% by mass and more particularly between 95% and 100% by mass, in particular between 95% and 99% by mass, of the total mass of the lubricating composition.

[0141] In a particular embodiment, a lubricating composition according to the invention is completely free of base oil other than re-refined lubricating oils.

[0142] In a particular embodiment, a lubricating composition according to the invention is formed solely from one or more re-refined lubricating oils. In other words, said re-refined lubricating oil(s) may represent 100% of the lubricating composition.

[0143] According to a particular embodiment, the at least partly re-refined lubricating oil is present in a content not exceeding 99%, or even 95% by mass of the total mass of the base oil of the lubricating composition.

[0144] In another embodiment, said re-refined lubricating oil(s) may represent more than 70% by mass of the total mass of the base oil of the lubricating composition, in particular more than 80% by mass, in particular more than 90% by mass and more particularly between 95% and 100% by mass, in particular between 95% and 99% by mass, of the total mass of the base oil of the lubricating composition.

[0145] In a particular embodiment, a lubricating composition according to the invention is formed solely from one or more re-refined lubricating oils. In other words, said re-refined lubricating oil(s) may represent 100% of the base oil of the lubricating composition.

[0146] In yet another particular embodiment, said re-refined lubricating oil(s) may represent more than 70% by mass of the total mass of the base oil of the lubricating composition and less than 99%, or even 95% by mass of the total mass of the base oil of the lubricating composition.

[0147] Additives

[0148] A lubricating composition implemented according to the invention may further comprise all types of additives suitable for the intended use of the lubricant, as detailed in the remainder of the text, for example for use in engine systems of light or heavy vehicles, or even marine vehicles, in combustion, electric or hybrid engine systems.

[0149] These additives may be chosen in particular from friction modifying additives, anti-wear additives, extreme pressure additives, detergents, antioxidants, viscosity index (VI) improvers, pour point depressants (PPD), dispersants, anti-foaming agents, thickeners, corrosion inhibitors, copper passivating agents, and mixtures thereof.

[0150] Advantageously, a lubricating composition according to the invention comprises one or more additives chosen from viscosity index improvers, pour point lowering additives, anti-wear additives, antioxidants and mixtures thereof.

[0151] These additives may be added to the said regenerated base oil(s) used according to the invention or to the mixture of the 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 “Energy efficiency” properties of the composition based on the said re-refined lubricating oil(s) are not or are not substantially altered by the envisaged addition.

[0152] A lubricating composition used according to the invention may comprise between 0.01 and 20% by mass, in particular between 0.05 and 10% by mass of additives, in particular as described below, relative to the total weight of the composition.

[0153] Thus, in one embodiment, said re-refined lubricating oil(s) may represent more than 70% by mass of the total mass of the base oil of the lubricating composition, in particular more than 80% by mass, in particular more than 90% by mass and more particularly between 95% and 100% by mass, in particular between 95% and 99% by mass, of the total mass of the base oil of the lubricating composition and the lubricating composition may further comprise between 0.01 and 20% by mass, in particular between 0.05 and 10% by mass of additives, in particular as described below, relative to the total weight of the composition. Said lubricating composition may then comprise from 99.99 to 80% by mass of base oil(s), in particular from 99.05 to 90% by mass of base oil(s) relative to the total weight of the composition.

[0154] In a particular embodiment, a lubricating composition according to the invention is formed solely from one or more re-refined lubricating oils. In other words, said re-refined lubricating oil(s) may represent 100% of the base oil of the lubricating composition. Said lubricating composition may then comprise from 99.99 to 80% by mass of re-refined lubricating oil(s), in particular from 99.05 to 90% by mass of re-refined lubricating oil(s) as the sole base oil(s) relative to the total weight of the composition.

[0155] Advantageously, a lubricating composition used according to the invention may comprise at least one friction-modifying additive. The friction-modifying additives make it possible to limit friction by forming adsorbed monolayers on the surfaces of the metals in contact with them. They may be chosen from compounds providing metallic elements and ash-free compounds. Among the compounds providing metallic elements, mention may be made of transition metal complexes such as Mo, Sb, Sn, Fe, Cu, Zn, the ligands of which may be hydrocarbon compounds comprising oxygen, nitrogen, sulfur or phosphorus atoms.The ash-free friction modifying additives are generally of organic origin and may be chosen from fatty acid esters and polyols, distinct from the monoester required according to the invention, alkoxylated amines, alkoxylated fatty amines, fatty epoxides, borate fatty epoxides, fatty amines or fatty acid glycerol esters. According to the invention, the fatty compounds comprise at least one hydrocarbon group comprising from 10 to 24 carbon atoms. In particular, the molybdenum-based compounds may be chosen from molybdenum dithiocarbamates (Mo-DTC), molybdenum dithiophosphates (Mo-DTP), and mixtures thereof.

[0156] Advantageously, a lubricating composition according to the invention may comprise from 0.01 to 5% by mass, preferably from 0.01 to 5% by mass, more particularly from 0.1 to 2% by mass or even more particularly from 0.1 to 1.5% by mass, relative to the total weight of the lubricating composition, of friction modifying additives.

[0157] Preferably, a lubricating composition according to the invention comprises at least one anti-wear additive, an extreme pressure additive or mixtures thereof. The anti-wear additives and the extreme pressure additives are dedicated to protecting the friction surfaces by forming a protective film adsorbed on these surfaces. There is a wide variety of anti-wear additives. Particularly suitable for the lubricating compositions according to the invention are the anti-wear additives chosen from polysulfide additives, sulfur-containing olefin additives or phospho-sulfur additives such as metal alkylthiophosphates, in particular zinc alkylthiophosphates, and more specifically zinc dialkyldithiophosphates or ZnDTP. The preferred compounds are of formula Zn((SP(S)(OR)(OR'))2, in which R and R', identical or different, independently represent an alkyl group, preferably comprising from 1 to 18 carbon atoms.

[0158] Advantageously, a lubricating composition according to the invention may comprise from 0.01 to 6% by mass, preferably from 0.05 to 4% by mass, more preferably from 0.1 to 2% by mass, relative to the total weight of the composition, of anti-wear additives and extreme pressure additives.

[0159] Advantageously, a lubricating composition according to the invention may comprise at least one antioxidant additive. The antioxidant additive makes it possible to delay the degradation of the lubricating composition in service. This degradation may in particular result in the formation of deposits, the presence of sludge or an increase in the viscosity of the lubricating composition. They act in particular as radical inhibitors or hydroperoxide destroyers.

[0160] Commonly used antioxidant additives include phenolic antioxidants, amine antioxidant additives, and phosphosulfur antioxidant additives. Some of these antioxidant additives, for example phosphosulfur antioxidant additives, may be ash-generating. Phenolic antioxidant additives may be ash-free or in the form of neutral or basic metal salts. The antioxidant additives may in particular be chosen from sterically hindered phenols, sterically hindered phenol esters, and sterically hindered phenols comprising a thioether bridge, diphenylamines, diphenylamines substituted with at least one C1-C12 alkyl group, N,N'-dialkylaryldiamines, and mixtures thereof.

[0161] Preferably, the sterically hindered phenols are chosen from compounds comprising a phenol group in which at least one vicinal carbon of the carbon bearing the alcohol function is substituted by at least one C1-C10 alkyl group, preferably a C1-C6 alkyl group, preferably a C4 alkyl group, preferably by the tert-butyl group. Amino compounds are another class of antioxidant additives that can be used, optionally in combination with the phenolic antioxidant additives. Examples of amino compounds are aromatic amines, for example aromatic amines of formula NR 5 R 6 R 7 in which R 5 represents an aliphatic group or an aromatic group, optionally substituted, R 6 represents an aromatic group, optionally substituted, R 7represents a hydrogen atom, an alkyl group, an aryl group or a group of formula R 8 S(O) Z R 9 in which R 8 represents an alkylene group or an alkenylene group, R 9 represents an alkyl group, an alkenyl group or an aryl group and z represents 0, 1 or 2. Sulphurized alkyl phenols or their alkali and alkaline earth metal salts can also be used as antioxidant additives.

[0162] Advantageously, a lubricating composition according to the invention may comprise from 0.1 to 2% by mass, relative to the total weight of the composition, of at least one antioxidant additive.

[0163] A lubricating composition according to the invention may also comprise at least one detergent additive. Detergent additives generally make it possible to reduce the formation of deposits on the surface of metal parts by dissolving secondary oxidation and combustion products. The detergent additives that can be used in a lubricating composition according to the invention are generally known to those skilled in the art. The detergent additives may be anionic compounds comprising a long lipophilic hydrocarbon chain and a hydrophilic head. The associated cation may be a metal cation of an alkali or alkaline-earth metal. The detergent additives are preferably chosen from alkali metal or alkaline-earth metal salts of carboxylic acids, sulfonates, salicylates, naphthenates, as well as phenate salts. The alkali and alkaline-earth metals are preferably calcium, magnesium, sodium or barium.These metal salts generally comprise the metal in stoichiometric quantity or in excess, therefore in a quantity greater than the stoichiometric quantity. These are then overbased detergent additives; the excess metal providing the overbased character to the detergent additive is then generally in the form of a metal salt insoluble in the base oil, for example a carbonate, a hydroxide, an oxalate, an acetate, a glutamate, preferably a carbonate.

[0164] A lubricating composition according to the invention may comprise from 0.5 to 8%, preferably from 0.5 to 4% by mass, relative to the total weight of the lubricating composition, of detergent additive.

[0165] Advantageously, a lubricating composition according to the invention may also comprise at least one pour point depressant additive (also called a “PPD” agent for “Pour Point Depressant” in English). By slowing down the formation of paraffin crystals, the pour point depressant additives generally improve the cold behavior of the lubricating composition according to the invention. Examples of pour point depressants include polyalkyl methacrylates, polyacrylates, polyarylamides, polyalkylphenols, polyalkylnaphthalenes and alkylated polystyrenes.

[0166] A lubricating composition according to the invention may comprise from 0.1% to 2%, preferably from 0.2% to 1% by mass of pour point lowering additive(s), relative to the total weight of the composition.

[0167] A lubricating composition according to the invention may also comprise at least one dispersing agent. Such dispersing agents ensure the maintenance in suspension and the evacuation of insoluble solid contaminants consisting of secondary oxidation products which form when the lubricating composition is in service. They may be chosen from Mannich bases, succinimides and their derivatives, such as polyisobutylene succinic anhydride derivatives.

[0168] In particular, a lubricating composition according to the invention may comprise from 0.2 to 10% by mass of dispersing agent(s), relative to the total weight of the composition.

[0169] A lubricating composition according to the invention may also comprise at least one viscosity index (VI) improving additive. Viscosity index improvers, in particular viscosity index improving polymers, make it possible to ensure good cold resistance and minimal viscosity at high temperatures. Examples of viscosity index improving polymers include hydrogenated or non-hydrogenated polymer esters, homopolymers or copolymers of styrene, butadiene and isoprene, homopolymers or copolymers of olefin, such as ethylene or propylene, polyacrylates and polymethacrylates (PMA), preferably homopolymers or copolymers of olefin, such as ethylene or propylene.

[0170] In particular, a lubricating composition according to the invention may comprise from 1 to 15% by mass of additive(s) improving the viscosity index, preferably from 5% to 10% by mass, relative to the total weight of the lubricating composition.

[0171] A lubricating composition may also comprise at least one anti-foam additive, for example chosen from polar polymers such as polymethylsiloxanes or polyacrylates. In particular, a lubricating composition according to the invention may comprise from 0.01 to 3% by mass of anti-foam additive(s), relative to the total weight of the lubricating composition.

[0172] It may also comprise at least one anti-corrosion agent or copper passivating agent, for example compounds such as succinic polyisobutene anhydrides, thiadiazole sulfonates or mercaptobenzothiazoles. They are typically present in a lubricating composition according to the invention at contents of between 0.01% and 1% by mass, relative to the total weight of the composition.

[0173] Thus, a lubricating composition according to the invention may further comprise 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 friction modifying additives, anti-wear additives, extreme pressure additives, detergents, antioxidants, viscosity index (VI) improvers, pour point depressant (PPD) additives, dispersants, anti-foaming agents, thickeners, corrosion inhibitors, copper passivating agents, and mixtures thereof.

[0174] APPLICATIONS

[0175] As previously indicated, re-refined oils, preferably having characteristics equivalent to those defined by the API classification for Group I or Group II base oils, are used according to the invention to improve the energy efficiency of lubricants intended for the lubrication of various engine systems.

[0176] These can be mobile or stationary motorization systems.

[0177] By "motorization system" within the meaning of the present invention, is meant a system comprising all the mechanical parts necessary for the intended mobile or stationary application and including by means of a motor. It may be a combustion, gas, in particular hydrogen, ammonia, electric or hybrid motorization system, depending on the nature of the motor(s) included in the motorization system: combustion, gas, in particular hydrogen, ammonia and / or electric engine.

[0178] A "stationary" drive system within the meaning of the invention is a drive system including a stationary engine. It may find applications, for example, in devices for producing electrical energy. It may in particular be a gas drive system, in particular a stationary gas engine.

[0179] A “mobile” motorization system is more specifically a motorization system implemented in vehicles, including light vehicles, heavy goods vehicles, so-called “off-road” mobile machines, or even marine vehicles.

[0180] A mobile motorization system can thus be a propulsion system of a vehicle, in particular a vehicle with a combustion engine, an electric or hybrid vehicle.

[0181] For the purposes of the present invention, the term "propulsion system" is intended to denote a system comprising the mechanical parts necessary for the propulsion of a vehicle. The propulsion system more particularly encompasses an engine, for example an internal combustion engine or an electric motor comprising the rotor-stator assembly of the power electronics, a transmission and possibly a battery. As indicated previously, the use of re-refined oils advantageously makes it possible to act effectively on the energy consumption of the engine via its impact on the friction forces generated between the various components of the engine system, for example the vehicle's propulsion system.

[0182] A lubricating composition can thus be used for the lubrication of gears, transmission components, in particular at the level of the reducer, gearbox and / or axles, of the engine.

[0183] In particular, the re-refined oils according to the invention can be used to reduce friction in the propulsion systems of light or heavy vehicles, in particular vehicles with combustion, electric or hybrid engines.

[0184] As non-limiting examples of the invention, the re-refined oil according to the invention may consist of at least one of the re-refined oils offered by the following suppliers: PROLUMINAS (BR), OSILUB (FR), TAM HOUSE (IN), SAHARA (IN), ENVIROIL (PT), CATOR (ES), SETERGO (ES), MASAFEE (EG), SOUTHERN OIL (AU), CLENAWAY (AU), PETROLUBE (BR), TERRAPURE (CA), FINAS (CN), BROAD (CN), JUNGU (CN), LWART (EG), TECOIL (FI), OSILUB+ (FR), AVISTA (DE), PURAGLOBE (DE), LPC HELLAS (GR), ITELYUM (IT), FFS REFINERS (ZA), TAYRAS (TR), REGENIII (USA), SAFETY KLEEN (USA), DAYA LUBRICANT (IN), LUBRICON (IN), IFP PETRO (IN), PLUS LUBRICANT (IN), PENTAS FLORA (MY).

[0185] The invention will now be described by means of the following examples, given by way of illustration and not limitation of the invention.

[0186] Example

[0187] Method for measuring kinematic viscosity

[0188] The kinematic viscosity of oils is measured at 100°C (KV100) using a viscometer, according to standard NF EN ISO 3104. This standard is technically equivalent to standard ASTM D445. The results are expressed in mm 2 / s (equivalent to centistoke, noted cSt).

[0189] Method of measuring viscosity index

[0190] The viscosity index is a dimensionless ratio that provides an indication of how the viscosity of oils varies with temperature. It is calculated from the kinematic viscosity values ​​at 40°C and 100°C, according to standard NF ISO 2909. The higher this index, the less the viscosity of oils is influenced by temperature variations.

[0191] Method for measuring sulfur and aromatic compound content

[0192] The sulfur and aromatic compound contents in the oil are determined by infrared or ultraviolet spectroscopy.

[0193] Method of measuring volatility

[0194] 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.

[0195] Evaluation of the traction coefficient of the compositions

[0196] The coefficient of traction (COT) was measured using the PCS instrument MTM tribometer. It is used to evaluate the performance of lubricants in terms of friction in mixed / hydrodynamic conditions. This test involves placing a steel ball and a steel plane in relative motion at different speeds, allowing the definition of the %SSR (Slide-to-Roll Ratio) which corresponds to the sliding speed / drive speed.

[0197] The measurement conditions were 25 N (920 MPa) load, a disc speed of 2500 - 20 mm / s for an SRR of 40% and an evaluated temperature of 40 °C and 100 °C.

[0198] The lower the traction coefficient for a lubricating composition, the more friction between metal parts is reduced, thus resulting in greater gain in terms of fuel economy.

[0199] Example 1

[0200] The properties of re-refined lubricating oils II to 110, in accordance with the invention and commercially available, were evaluated. These oils are obtained from used base oils and having undergone at least one step of dehydration, distillation, filtration, hydrogenation, liquid / liquid extraction, 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.

[0201] Two new lubricating oils Cl and C2, not in accordance with the invention because they had not undergone any recycling or re-refining step, were also evaluated.

[0202] These oils are commercially available API Group I or II base oils.

[0203] In particular, the kinematic viscosity at 100°C, viscosity index, traction coefficients at 40°C and 100°C, as well as the Noack volatility of these oils were measured according to the protocols detailed above.

[0204] The results are presented in Table 2 for re-refined and virgin oils with characteristics equivalent to those defined by the API classification for Group I base oils and in Table 3 for re-refined and virgin oils with characteristics equivalent to those defined by the API classification for Group II base oils, below.

[0205] [Table 2]

[0206]

[0207] [Table 3]

[0208]

[0209] It can be observed that the re-refined lubricating oils according to the invention have lower traction coefficients compared to the new reference oils.

[0210] A lower traction coefficient reduces friction losses in mechanical contacts working in full film and thus reduces the fuel used. The traction coefficient is lower over a wide temperature range (from 40 to 100°C), corresponding to temperatures at the engine crankcase.

[0211] Furthermore, the majority of re-refined lubricating oils exhibit reduced volatility compared to that measured for virgin oils. Lower base oil volatility allows for the use of thinner base oils in lubricant formulations; this further maximizes Fuel-Eco gains.

Claims

Claims 1. Use of at least one at least partially re-refined lubricating oil to improve the energy efficiency properties of a lubricating composition intended for a motorization system.

2. Use according to the preceding claim, for reducing the traction coefficient of the lubricating composition.

3. Use according to claim 1 or 2, for reducing the Noack volatility of the lubricating composition.

4. 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.

5. Use according to any one of the preceding claims, in which the at least partly re-refined lubricating oil has characteristics in terms of saturated compound content, sulfur content and viscosity index, satisfying the criteria defined by the API classification for group I oils or group II oils.

6. Use according to any one of the preceding claims, in which the at least partly re-refined lubricating oil has a kinematic viscosity measured at 100°C according to ASTM D445 of greater than or equal to 4.0 mm 2 / s, in particular between 4.0 and 12 mm 2 / s, in particular greater than or equal to 4.3 mm 2 / s and more particularly between 4.4 and 10 mm 2 / s, especially between 4.5 and 6 mm 2 / s.

7. Use according to any one of the preceding claims, in which the at least partly re-refined lubricating oil has a viscosity index, determined according to standard NF ISO 2909, greater than or equal to 110, in particular between 110 and 130, preferably between 112 and 125 and more particularly between 112 and 122.

8. Use according to any one of the preceding claims, in which the at least partly re-refined lubricating oil has a Noack volatility, determined according to the CEC L-40-93 standard, of less than or equal to 15%, in particular less than or equal to 14%, preferably strictly less than 12%, in particular between 7% and 11%.

9. Use according to any one of the preceding claims, in which the at least partly re-refined lubricating oil, in particular the characteristics of which are equivalent to those defined by the API classification for group I or group II base oils, has a reduced traction coefficient of at least 7%, in particular at least 10%, advantageously at least 15%, in particular at least 20%, or even at least 25%, compared to the traction coefficient of a virgin base oil of equivalent group according to the API classification.

10. Use according to any one of the preceding claims, in which the at least partly re-refined lubricating oil 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.

11. Use according to any one of the preceding claims, in which the at least partly re-refined lubricating oil 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.

12. Use according to any one of the preceding claims, wherein said composition further 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 friction modifying additives, anti-wear additives, extreme pressure additives, detergents, antioxidants, viscosity index (VI) improvers, pour point depressants (PPD), dispersants, anti-foaming agents, thickeners, corrosion inhibitors, copper passivators, and mixtures thereof.

13. Use according to any one of the preceding claims, said at least partly re-refined lubricating oil(s) representing more than 70% by mass of the total mass of the lubricating composition, in particular more than 80% by mass, in particular more than 90% by mass and more particularly between 95% and 99% by mass, relative to the total mass of said lubricating composition.

14. Use of a lubricating composition based on at least one at least partly re-refined lubricating oil, in particular as defined in claims 4 to 11, for reduce the energy consumption of a lubricated engine system using said lubricating composition.

15. Use according to claim 14, said motorization system being a mobile or stationary, combustion, electric or hybrid motorization system, in particular in a vehicle, in particular in a light vehicle, heavy-duty vehicle or marine vehicle.

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