Use of at least partially re-refined lubricating oils to reduce wear

Abstract

The present application relates to the use of at least one at least partially re-refined lubricating oil to reduce the wear of parts in a mechanical system, in particular the wear of moving parts in a mechanical system.

Description

[0001] Description

[0002] Title: Use of at least partly re-refined lubricating oils to reduce wear

[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 mechanical systems, in particular in vehicles.

[0005] It relates more particularly to the use of re-refined lubricating oils to reduce wear of parts in a mechanical system, in particular wear of moving parts in a mechanical system, and in particular to reduce pitting of moving parts in a mechanical system.

[0006] Prior art

[0007] A typical cause of damage to mechanical systems is fatigue damage, which occurs under repeated stresses. This phenomenon is induced by repeated rolling stresses under heavy loads. This results in particular in pitting phenomena (surface fatigue).

[0008] Prevention of this phenomenon involves reducing contact stresses through appropriate part geometry, and reducing friction by avoiding adhesion.

[0009] As such, lubricating compositions, also known as "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, and thus protecting the parts against wear. They are thus used to prevent premature wear or even damage to these parts, and in particular to their surface.

[0010] To do this, a lubricating composition is classically composed of one or more base oils, to which are generally associated several additives dedicated to stimulating the lubricating performance of the base oils, such as for example friction modifying additives.

[0011] The lubricant thus plays a role in the prevention process, due to its viscosity and the physicochemical reactivity of its additives. Thus, a particularly useful type of performance for a lubricating composition of mechanical systems consists of presenting good wear resistance properties, properties which are systematically part of the prerogatives to be respected in the manufacturers' specifications.

[0012] To this end, various solutions have been proposed, such as the use of surface treatments, sulfur and / or phosphorus additives in the compositions, or nanoparticles. However, these solutions have not proven satisfactory in several respects.

[0013] Indeed, sulfur additives, as well as phosphorus and phospho-sulfur additives, are widely used in oil formulations as anti-wear and extreme pressure additives. They protect parts in friction under high load by forming an adsorbed film on their surface. Sulfur additives help prevent seizure, a phenomenon that occurs in the early stages of use, when the interface strength exceeds that of the underlying material.

[0014] However, despite the existence of a large number of anti-wear additives, extreme pressure additives or friction modifying additives, not all have the same effectiveness, some being able to improve one property and at the same time deteriorate a second property.

[0015] Similarly, the chemistry of these additives is complex and the additives can react with each other to form new chemical species whose influence on extreme pressure, wear, friction and seizure properties is ultimately unknown.

[0016] Furthermore, the proposed surface treatments are expensive and nanoparticles have problems with stability in suspension, causing clogging of filters in mechanical machines. Furthermore, these solutions are not satisfactory from an environmental point of view.

[0017] In this respect, to meet a growing expectation to free ourselves from the use of toxic solvents and to reduce the impact of products on the environment, studies have also focused on the development of water-based lubricants.

[0018] For example, application WO 2021 / 259853 has described an aqueous lubricating composition comprising a polyalkylene glycol, an antifreeze compound and a phosphorus compound. However, this type of aqueous lubricant is not entirely satisfactory with regard to the phenomenon of pitting due to mechanical fatigue that it is likely to cause. Indeed, it has been observed that this lubricating composition can generate this type of failure in mechanical contacts, in particular depending on the formulation protocol of the composition.

[0019] There is therefore a need to increase the lifespan of friction parts in mechanical systems, by limiting the appearance of wear phenomena, and in particular pitting due to mechanical fatigue.

[0020] There also remains a need for more environmentally friendly lubricating compositions, while exhibiting excellent properties in terms of reducing wear, and in particular pitting phenomena due to mechanical fatigue.

[0021] Statement of the invention

[0022] The present invention aims to propose the use of specific oils making it possible to meet these expectations.

[0023] More particularly, the inventors have discovered that recycled lubricating base oils are particularly suitable for use in lubricating compositions, to reduce wear of parts in a mechanical system, in particular wear of moving parts in a mechanical system.

[0024] Summary of the invention

[0025] The present invention aims precisely to propose a new use of at least partly re-refined lubricating oil making it possible to reduce, or even eliminate, wear phenomena, in particular pitting due to mechanical fatigue.

[0026] 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 to reduce the wear of parts in a mechanical system, in particular the wear of moving parts in a mechanical system.

[0027] Surprisingly, as is evident from the examples which follow, the inventors have discovered that re-refined oils, originating from used oil recycling channels, make it possible to access lubricants having improved properties in terms of reducing wear of parts in a mechanical system, and in particular reducing pitting by mechanical fatigue of moving parts in a mechanical system.

[0028] 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 derived from a used lubricating composition having been subjected to one or more treatment steps known as re-refining treatment.

[0029] 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.

[0030] According to the invention, the term "moving parts" is intended to mean any association of at least two parts exhibiting any relative movement between them. This may in particular be parts, in particular metal parts in a rolling system, in particular within an engine, in a transmission system or in a hydraulic circuit.

[0031] 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".

[0032] 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.

[0033] Methods for re-refining or reconditioning used lubricating oils have been developed in order to regenerate these oils and allow their subsequent reuse. 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.

[0034] Preferably, as detailed in the remainder 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.

[0035] The at least partly re-refined lubricating oils used according to the invention preferably have a kinematic viscosity measured at 100°C according to the ASTM D445 standard greater than or equal to 4.0 mm 2 / s, notably ranging from 4.0 to 12 mm 2 / s, in particular greater than or equal to 4.3 mm 2 / s and more particularly varying from 4.4 to 10 mm 2 / s, especially from 5.0 to 6.5 mm 2 / s.

[0036] To the inventors' knowledge, it has never been proposed to use a recycled lubricating oil to reduce wear of parts in a mechanical system, and more particularly to reduce pitting by mechanical fatigue of moving parts in a mechanical system.

[0037] "Mechanical fatigue pitting" means the fatigue deterioration of surfaces, particularly surfaces of moving parts in a mechanical system, due to the removal of fragments of various sizes from said parts formed by the propagation of fatigue cracks.

[0038] The appearance of fatigue cracks is caused by the accumulation of cyclic stresses exceeding the fatigue limits of the parts. Pitting by superficial mechanical fatigue particularly affects the metal surfaces of parts, especially in highly loaded Hertzian contact, subjected to a pure or mixed elastohydrodynamic regime in pure rolling or rolling accompanied by sliding.

[0039] The use according to the invention of a re-refined lubricating oil to reduce wear of parts in a mechanical system proves advantageous in several respects. On the one hand, as illustrated in the examples which follow, the inventors have shown that re-refined lubricating oils make it possible to prevent pitting by mechanical fatigue of moving parts, in particular moving parts in a motorization system, at least to the same extent as lubricating compositions whose only base oils are new base oils.

[0040] Indeed, surprisingly, the inventors discovered that re-refined lubricating oils make it possible to improve the resistance to pitting by mechanical fatigue of moving parts, in particular moving parts in a motorization system, compared to a lubricating composition comprising, as base oil, only new base oil of the same origin. To the inventors' knowledge, such results had never been obtained until then.

[0041] 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.

[0042] On the other hand, the use of recycled lubricating oils advantageously meets current expectations for reducing environmental impact and conserving resources. Thus, the use of regenerated lubricating oils advantageously reduces the carbon footprint of products, compared to the use of virgin base oils.

[0043] In a particular embodiment, the invention relates to the use of at least one at least partially re-refined lubricating oil to reduce pitting by mechanical fatigue of moving parts in a mechanical system.

[0044] As detailed in the rest of the text, said moving parts may constitute all or part of a motorization system, in particular 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.

[0045] According to another aspect, the invention also relates to the use of at least one lubricating composition comprising at least one at least partially re-refined lubricating oil, for reducing wear of parts in a mechanical system, in particular wear of moving parts in a mechanical system, and more particularly for reducing pitting by mechanical fatigue of moving parts in a mechanical system. 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 75% by mass and more particularly more than 80% by mass, of the total mass of the composition containing it or them.

[0046] 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.

[0047] Said re-refined lubricating oil(s) may be used in combination with one or more other ingredients. In particular, they may be supplemented with one or more additives, such as, for example and without limitation, anti-corrosion additives, antioxidant additives, etc.

[0048] The present invention also relates to a method for reducing wear of parts in a mechanical system, in particular pitting by mechanical fatigue of moving parts in a mechanical system, comprising at least one step of circulating at said mechanical system a composition based on at least one lubricating oil which is at least partly re-refined.

[0049] It also relates to a process or method for preparing a lubricating composition comprising at least one step of obtaining a lubricating oil at least partly re-refined from a used lubricant.

[0050] The process for preparing the composition may more particularly comprise the steps consisting of:

[0051] (i) preparing an at least partly re-refined lubricating oil from a used lubricant;

[0052] (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

[0053] (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 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.

[0054] 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 above, the use of re-refined base oils makes it possible to effectively reduce the wear of parts in a mechanical system, in particular the wear of moving parts in a mechanical system, and more particularly pitting by mechanical fatigue of moving parts in a mechanical system.

[0055] Other characteristics, variants and advantages of the use of at least partly re-refined lubricating oils and of the compositions containing them will become more apparent upon reading the description and examples which follow, given by way of illustration and not limitation of the invention.

[0056] The expressions "between ... and ...", "ranging from ... to ...", "formed from ... to ...", and "varying from ... to ...", must be understood inclusively, unless otherwise stated.

[0057] 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.

[0058] Brief description of the drawings

[0059] [Fig 1] represents the two-dimensional chromatogram of a first re-refined lubricating oil according to the invention, oil J of the experimental part.

[0060] [Fig 2] represents the two-dimensional chromatogram of a second re-refined lubricating oil according to the invention, oil H of the experimental part.

[0061] Detailed description Lubricating oil at least partly re-refined

[0062] As previously specified, the oil used 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.

[0063] 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.

[0064] 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.

[0065] H can be a mixture of several base oils, for example a mixture of two, three, or four base oils.

[0066] 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.

[0067] In particular, 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.

[0068] [Table 1]

[0069] 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 from 60% to 99% by weight of base oil(s).

[0070] 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.

[0071] The invention thus aims at the use 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.

[0072] 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.

[0073] According to another particular embodiment, the re-refined lubricating oil used according to the invention may be derived 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, but not limited to, turbines, compressors, hydraulic systems, gears, or even forming or cutting machines. A used lubricating composition, from which the regenerated lubricating oil used according to the invention is derived, may contain various conventional additives in the field of lubricants, such as friction modifying additives, extreme pressure additives, anti-wear additives, detergents, antioxidants, viscosity index (VI) improvers, pour point depressants (PPD) additives, dispersing agents, anti-foaming agents, thickeners, and mixtures thereof.

[0074] 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.

[0075] 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.

[0076] 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.

[0077] 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.

[0078] 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.

[0079] 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.

[0080] Thus, the invention relates to the use of 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.

[0081] 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.

[0082] Preferably, 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.

[0083] 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.

[0084] According to one embodiment, the dehydration step can be carried out at a temperature ranging from 50°C to 250°C, preferably from 100°C to 200°C. In particular, it can be carried out at a pressure ranging from 50,000 to 150,000 Pa, preferably at atmospheric pressure.

[0085] 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.

[0086] 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) 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 ranging from 100°C to 500°C, preferably from 200°C to 400°C, more preferably from 300°C to 380°C. In particular, they may be carried out at a pressure ranging from 25 to 2000 Pa, preferably from 50 to 1000 Pa, more particularly from 50 to 250 Pa.

[0087] Preferably, 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.

[0088] The adsorbent material advantageously allows the selective adsorption of aromatic compounds, in particular PAHs.

[0089] 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.

[0090] The term "passage of the used lubricating composition over an adsorbent material" means the flow of the used lubricating composition over the adsorbent support.

[0091] The adsorbent materials can be, for example, activated carbon, zeolites, clays or functionalized porous compounds. Preferably, it is activated carbon.

[0092] For example, the regenerated lubricating oil used according to the invention can be obtained from the treatment of a used lubricating composition according to the method described in document WO 2018 / 109208.

[0093] In the case of passing the used lubricating composition over activated carbon, the quantity of activated carbon used preferably varies from 0.5 to 60 g of activated carbon per liter of used lubricating composition, preferably from 0.5 to 50 g / L, preferably from 1 to 50 g / L, preferably from 1 to 30 g / L, for example from 5 to 60 g / L, preferably from 5 to 50 g / L.

[0094] The flow rate of the used lubricating composition can vary from 1 m 3 / h at 15 m 3 / h, for example from 5 to 10 m 3 / h.

[0095] Preferably, the activated carbon is characterized by a density ranging from 200 to 500 kg / m 3 , for example measured according to ASTDM D2854.

[0096] Preferably, the activated carbon is a coal, preferably comprising from 70 to 95%, preferably from 80 to 90% by weight of carbon.

[0097] The step of passing the used lubricating composition onto an adsorbent support, preferably onto activated carbon, is advantageously preceded by the following preliminary steps:

[0098] - one or more distillation stages; and

[0099] - a filtration step, in particular as defined previously.

[0100] Preferably, 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.

[0101] Preferably, 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.

[0102] Preferably, 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 carried out by any technique known to those skilled in the art.

[0103] 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. 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.

[0104] A regenerated lubricating oil used according to the invention is in particular characterized by a silicon content varying from 0 ppm to 300 ppm, in particular varying from 1 to 300 ppm. A regenerated lubricating oil used according to the invention is in particular characterized by a phosphorus content less than or equal to 100 ppm, in particular varying from 0 ppm to 100 ppm, for example 0 ppm.

[0105] 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 varying from 0 ppm to 50 ppm, for example 0 ppm.

[0106] The content of these elements can be assessed by any method known to those skilled in the art, for example by X-ray fluorescence (XRF), or by infrared or ultraviolet spectroscopy.

[0107] According to one embodiment, a re-refined lubricating oil according to the present invention comprises one or more alkylphenol(s). By "alkylphenol" is meant a phenolic compound with an alkyl group Ri in the para position, and therefore of formula Ri-Côtk-OH. The presence of alkylphenol is characteristic of re-refined lubricating oils, since native (unused) oils do not comprise alkylphenol.

[0108] Preferably, the content of alkylphenol(s) in the re-refined lubricating oil according to the present invention ranges from 5 to 3200 ppm, in particular from 10 to 2000 ppm, preferably from 15 to 1500 ppm, of alkylphenol(s).

[0109] According to one embodiment, a re-refined lubricating oil according to the present invention comprises from 10 to 300 ppm, preferably from 15 to 250 ppm, of alkylphenol(s).

[0110] According to another embodiment, a re-refined lubricating oil according to the present invention comprises from 150 to 2,000 ppm, preferably from 200 to 1,500 ppm, of alkylphenol(s).

[0111] The alkylphenol(s) content in the re-refined lubricating oil is measured according to the method described in the patent application filed under number FR 23 15133. This method is based on the implementation of liquid chromatography and mass spectrometry steps, using a standard compound which is 4-hexadecylphenol. For the liquid chromatography steps, a column filled with particles composed of Cs-grafted silica is used. The measurements are carried out at 40 °C with a flow rate of 0.4 mL / min.

[0112] Here, a so-called reversed-phase column is used to separate the different components of the sample (here, re-refined lubricating oil to be analyzed) according to their polarity. The composition of the mobile phase is used to modify these interactions over time and thus gradually elute the different molecules of the sample analyzed (here, re-refined lubricating oil).

[0113] The mobile phase is used in the form of a gradient as shown in the table below, from a solution A comprising 50% water and 50% acetonitrile and a solution B comprising 100% methanol.

[0114] Using mass spectrometry detection, it is then possible to obtain only the signal produced by the molecules of interest, identified both by their mass and their retention time.

[0115] The ionization source used is preferably the electrospray ionization (ESI) source which allows the selective ionization of polar compounds. In the case of the method used here, the detection mode chosen is the negative detection mode because it allows the selective ionization of polar compounds with an acidic character. The range for mass / charge ratios (m / z) varies from 100 to 1200.

[0116] In particular, the method for measuring the alkylphenol content in the re-refined lubricating oil used according to the invention comprises a first step consisting in preparing the standard solution (4-hexadecylphenol) and the solution to be analyzed (re-refined lubricating oil): - preparation of a standard solution at different concentrations to obtain a calibration line as explained later, by dilution in THF with the addition of 2% ammonium hydroxide; and - preparation of a solution of said re-refined lubricating oil by dilution in THF with the addition of 3% ammonium hydroxide.

[0117] To establish the calibration curve, the intensity of the chromatographic peak associated with the 4-hexadecylphenol ion of the standard is recovered by plotting an extracted ion chromatogram (EIC). This allows to have an extracted chromatogram only for a given m / z ratio, namely here 317.28 for the standard molecule, the deprotonated form corresponding to the C22H37O- ion. The intensity of the EIC is therefore recovered for each of the analyses at the different concentrations tested.

[0118] The data obtained allow the construction of the calibration line. This calibration line is obtained by injecting several standard solutions at different concentrations: the line is constructed by linear regression, and the calculation of the correlation coefficient (R 2 ) allows to check the linearity of the detector and the correct preparation of the standard solutions.

[0119] The associated equation then allows us to predict the concentration of an unknown sample by entering the experimentally obtained y value. Here, the equation is: y = 1001.9x - 15309

[0120] To quantify the alkylphenols in the re-refined lubricating oil according to the invention, the analysis method comprises a step of identifying the m / z ratios of the alkylphenol residues on the average mass spectrum by integrating the entire chromatogram. This average spectrum corresponds to an average of all the mass spectra obtained on the complete chromatographic run. This makes it possible to have all the compounds that were ionized during the analysis. From this average mass spectrum is extracted a mass list grouping together all the m / z ratios of the ions with the associated intensities.

[0121] The next step is to construct a Kendrick diagram with this mass list. This is a molecular map that allows us to identify series of compounds of the same type, but with different degrees of alkylation, by overcoming the mass defect of the hydrogens of the CH2 motif.

[0122] The Kendrick diagram can be made by calculating the following values:

[0123] 14,00000

[0124] KM = mass (IUPAC or EXPER)

[0125] K J 14.01565 where KM corresponds to the Kendrick mass, IUP AC mass corresponds to the theoretical mass calculated from the sum of each element constituting the molecule of interest, here for the standard molecule hexadecylphenol of formula CiithvO', the IUP AC mass = 317.284440 g. mol' 1 , and EXPER mass corresponds to an experimental mass measurement, measured during an experiment.

[0126] The Kendrick mass KM is calculated for each peak of the average mass spectrum, determined previously as explained above.

[0127] Then, the Kendrick MKD mass defect is typically calculated according to the following equation:

[0128] KMD = NKM - KM where KMD corresponds to the Kendrick mass defect,

[0129] KM corresponds to the Kendrick mass, and

[0130] NKM is the nearest integer rounding of the Kendrick mass KM.

[0131] The Kendrick KMD mass defect is calculated for each peak (each peak corresponding for example to a compound present in the re-refined lubricating oil).

[0132] Kendrick diagrams are a 2D molecular map representing KMDs versus NKMs. Homologous compounds varying in their degree of alkylation appear as a horizontal line.

[0133] The set of m / z ratios of the alkylphenols is obtained by applying a filter on the y-axis (KMD): this is the value KMD = 0.069. Once all the m / z ratios at KMD = 0.069 are identified, they are used to construct extracted ion chromatograms (EIC) as described for the standard molecule. This allows to have a chromatogram dependent only on the requested m / z ratio. The intensities of the EIC of each m / z ratio corresponding to the alkylphenols are thus summed to have the total intensity (several alkylphenol type molecules are obtained on the spectra of re-refined lubricating oil according to the invention, these molecules varying by the length of their alkyl chain).

[0134] To obtain a quantification, the sum of the intensities of the obtained EICs is used as the value of y for the equation of the calibration line. For example, if the obtained value is 2.45 E6, the quantification of alkylphenol residues in the re-refined lubricating oil used according to the invention is: y = 1001.9% - 15309 y + 15309

[0135] X ~ 1001.9 and therefore x is equal to 2460.6 ppm.

[0136] According to one embodiment, a re-refined lubricating oil according to the present invention comprises one or more polyalphaolefins (PAOs). The presence of polyalphaolefin(s) is characteristic of re-refined lubricating oils, since native (unused) oils do not comprise polyalphaolefins (PAOs).

[0137] Figures 1 to 2 represent two-dimensional chromatograms of two re-refined lubricating oils according to the present invention. The arrow in each of the figures indicates the characteristic peak of PAO (at C30), a marker of re-refined oils.

[0138] According to one embodiment, a re-refined lubricating oil according to the present invention comprises one or more polyalphaolefins (PAOs) comprising less than 40 carbon atoms, and preferably comprising 30 carbon atoms.

[0139] The presence of PAOs in re-refined lubricating oil is determined according to the method described in the patent application filed under number FR 2406231.

[0140] This method is based on the implementation of comprehensive two-dimensional gas chromatography (GCxGC) and classification steps.

[0141] In particular, it is implemented via a chromatography device, the chromatography device comprising a comprehensive two-dimensional gas chromatography module comprising a first column A and a second column B, and capable of separating different compounds of the product according to their volatility and their polarity, the chromatography device further comprising a flame ionization detector capable of measuring an intensity of electric ionization current generated for each compound included in the product, the chromatography device being calibrated with at least one calibration product, making it possible to correct the retention time of the different compounds present in the product. The method is furthermore implemented by an electronic classification device, comprising the following steps: a.determining a table describing the intensity of the ionization electric current generated for each compound included in the product as a function of the corrected retention times in columns A and B, from a measurement carried out by the chromatography device on the product; b. assigning a class to the product, from among a plurality of classes, by applying a multivariate statistical algorithm to the table, said algorithm being trained on tables obtained from reference products.

[0142] The chromatography device comprises a comprehensive two-dimensional gas chromatography module comprising a first column A and a second column B. The comprehensive two-dimensional gas chromatography modules (2DGC or GCxGC) that can be used in the context of the present disclosure are those described in the literature.

[0143] These modules generally include an injection module, a vaporization module, a first column A, a modulator, and a second column B. They allow a two-dimensional separation of complex mixtures, because the product is subjected to two separations, we then obtain a two-dimensional chromatogram as a function of the retention times of columns A and B and a table describing the intensity of the electric ionization current generated for each compound included in the product as a function of the corrected retention times in columns A and B.

[0144] According to one embodiment, the first column A and the second column B are columns based on polydimethylsiloxane partially functionalized with phenyl groups. The percentage of phenyl group functionalization may be between 2% and 50%. According to a particular embodiment, the percentage of phenyl group functionalization of column A is greater than the percentage of phenyl group functionalization of column B. Advantageously, the length of column A is greater than that of column B. The diameter of the two columns A and B may be equivalent. The two columns may have a film thickness of 0.1 pm suitable for the separation of low-volatile samples. According to one embodiment, the temperature gradient applied to the oven is 2°C / min up to 400°C.A quantity of product is injected into the first column A to obtain a first separation, then via the modulator, into the second column B to obtain a second separation. The product can be injected directly without pretreatment, particularly in the case of lubricating oil analysis.

[0145] The GCxGC device is coupled to a flame ionization detector, or FID. This is capable of measuring the intensity of the ionization electrical current generated for each compound included in the product. The flame ionization detector is located at the outlet of the second column.

[0146] Following analysis by the flame ionization detector, a table describing the intensity of the ionization electric current generated for each compound included in the product, as a function of the corrected retention times in columns A and B, is determined. The table is therefore derived from a two-dimensional chromatogram obtained from a measurement carried out by the chromatography device on the product.

[0147] In addition, during this initial step, an external calibration is performed to correct the retention time of the various compounds present in the product. This is performed by injecting at least one calibration product. In the case where the product to be classified is a lubricating oil, the calibration product may be a lubricating oil, preferably recycled. According to one embodiment, the calibration product comprises at least one marker, preferably at least two markers. The marker may be selected from n-paraffins, polyalphaolefins, and their mixture. The correction of the retention times may be performed by software.

[0148] At the end of this initial step, the classification device moves on to a next step, during which it assigns, via its product assignment module, a respective class from among the plurality of classes, by applying a multivariate statistical algorithm to the table, said algorithm being trained on tables obtained from reference products.

[0149] The multivariate statistical algorithm used in the allocation step may be a partial least squares regression multivariate statistical algorithm; the multivariate statistical algorithm preferably being selected from the group consisting of: a partial least squares regression algorithm, and a partial least squares regression algorithm with discriminant analysis. The algorithm is typically a partial least squares regression algorithm, such as the PLS algorithm or the PLS-DA algorithm. The multivariate statistical algorithm used in the allocation step is trained on tables obtained from reference products.

[0150] In Partial Least Squares Discriminant Analysis (PLS-DA), the prediction coefficient on a scale of 0 to 1 represents the probability or confidence of a sample belonging to a particular class.

[0151] Here is how this coefficient is calculated and used:

[0152] 1. Creation of latent variables:

[0153] PLS-DA creates latent variables (components) that capture the maximum variance of the X data (the predictors) while maximizing the covariance with the Y classes (the categorical responses).

[0154] 2. Calculation of scores:

[0155] Samples are projected onto these latent variables, producing scores that are used to discriminate between classes.

[0156] 3. Modeling:

[0157] A linear model is fitted to these scores to predict the values ​​of Y. In the case of PLS-DA, Y is often binary encoded to represent classes (e.g., 0 for group A and 1 for group B).

[0158] 4. Prediction:

[0159] When predicting for new samples, the scores of these samples are calculated and passed through the linear model to obtain a continuous prediction. This continuous prediction is then transformed into a probability on a scale of 0 to 1.

[0160] 5. Interpretation of probabilities:

[0161] These probabilities are then interpreted to assign the samples to the different classes.

[0162] For example :

[0163] - If the probability is less than 0.4, the sample is classified in group A (here group of re-refined base oils); and

[0164] - If the probability is greater than or equal to 0.4, the sample is classified in group B (conventional base oil group).

[0165] 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.

[0166] 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.

[0167] 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.

[0168] In particular, as previously indicated, surprisingly, a reclaimed lubricating oil exhibits excellent thermo-physical and hydraulic properties, particularly in terms of viscosity index, density, Noack volatility, flash point and / or thermal conductivity, and advantageously superior thermo-physical and hydraulic properties to those of a virgin base oil.

[0169] Preferably, the regenerated lubricating oil used according to the invention has a kinematic viscosity measured at 100°C according to the ASTM D445 standard varying from 2 to 12 mm 2 / s' x , especially 3 to 10 mm 2 / s .

[0170] Preferably, the kinematic viscosity measured at 100°C according to ASTM D445 of the at least partially re-refined lubricating oil is greater than or equal to 4.0 mm 2 / s, notably ranging from 4.0 to 12 mm 2 / s, in particular greater than or equal to 4.3 mm 2 / s and more particularly varying from 4.4 to 10 mm 2 / s, especially from 5.0 to 6.5 mm 2 / s.

[0171] Preferably, the regenerated lubricating oil used according to the invention has a kinematic viscosity measured at 40°C according to the ASTM D445 standard varying from 20 to 40 mm 2 / s, especially 25 to 40 mm 2 / s, and more particularly from 26 to 35 mm 2 / s.

[0172] Preferably, a regenerated 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 vary from 110 to 130, in particular from 115 to 125. The viscosity index can in particular be determined according to the EN ISO 2909 standard. Preferably, a regenerated lubricating oil used according to the invention has a Noack volatility less than or equal to 15%. The Noack volatility of the at least partly re-refined lubricating oil can thus vary from 5% to 15%.

[0173] More preferably, a regenerated lubricating oil used according to the invention has a Noack volatility strictly less than 12%, in particular ranging from 5% to 12%, and more particularly ranging from 6% to 11.5%.

[0174] Noack volatility can be determined in particular according to the CEC L-40-93 standard.

[0175] Preferably, a regenerated lubricating oil used according to the invention has a sulfur content varying from 0.001% to 0.2% by mass, in particular from 0.01% to 0.2% by mass, more particularly from 0.02% to 0.2% by mass, in particular ranging from 0.09% to 0.15% by mass, relative to the total mass of said regenerated lubricating oil.

[0176] Preferably, a regenerated lubricating oil used according to the invention has a content of aromatic compound(s) greater than or equal to 0.01% by mass, more particularly ranging from 0.02% to 10% by mass, relative to the total mass of said regenerated lubricating oil.

[0177] 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.

[0178] The 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:

[0179] - a kinematic viscosity measured at 100°C according to ASTM D445 greater than or equal to 4.0 mm 2 / s, for example ranging from 4.0 to 12 mm 2 / s, more particularly from 4.4 to 10 mm 2 / s ;

[0180] - a viscosity index greater than or equal to 110, in particular varying from 110 to 130, in particular from 115 to 125;

[0181] - a Noack volatility less than or equal to 15%, in particular varying from 5% to 15%, preferably strictly less than 12%, more particularly ranging from 5% to 12%, and more particularly ranging from 6% to 11.5%;

[0182] - a sulfur content varying from 0.001% to 0.2% by mass, in particular from 0.01% to 0.2% by mass, in particular varying from 0.02% to 0.2% by mass, in particular ranging from 0.09% to 0.15% by mass, relative to the total mass of said regenerated lubricating oil;

[0183] - a content of aromatic compound(s) greater than or equal to 0.01% by mass, more particularly ranging from 0.02% to 10% by mass, relative to the total mass of said regenerated lubricating oil.

[0184] Preferably, 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 3 The density of the at least partly re-refined lubricating oil can thus vary from 830 to 870 kg / m 3 , in particular from 840 to 860 kg / m 3 .

[0185] The density can in particular be determined according to standard NF EN ISO 12185.

[0186] Preferably, 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 vary from 225°C to 245°C.

[0187] The flash point can in particular be determined according to standard NF EN ISO 2592.

[0188] Preferably, 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 vary from 125 to 145 mW / mK, in particular from 128 to 140 mW / mK.

[0189] Thermal conductivity can be determined in particular according to ASTM D7896-19.

[0190] 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 exhibit excellent performance.

[0191] A high viscosity index makes it possible to have a composition whose viscosity varies little with temperature.

[0192] 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.

[0193] In particular, the at least partly re-refined lubricating oils are chosen from those marketed by the companies Proluminas, Osilub, Tam house, Sahara, Enviroil, Cator, Setergo, Masafee, Southern Oil, Cienaway, Petrolube, Terrapure, Finas, Broad, Jungu, LWART, Tecoil, Osilub+, Avista, Puraglobe, LPC Hellas, Itelyum, FFS Refiners, Tayras, ReGENIII, Safety Kleen, Daya Lubricant, Lubricon, IFP Petro, Plus Lubricant, or Pentas Flora.

[0194] Lubricating composition

[0195] 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.

[0196] 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.

[0197] Preferably, 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.

[0198] A lubricating composition used 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.

[0199] 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.

[0200] Preferably, a lubricating composition according to the invention is formed mainly from said re-refined lubricating oil(s).

[0201] In particular, said re-refined lubricating oil(s) may represent more than 50% by mass of the total mass of the composition containing it(s), in particular more than 70% by mass, in particular more than 75% by mass and preferably more than 80% by mass, of the total mass of the composition containing it(s).

[0202] Said re-refined lubricating oil(s) may also represent more than 90% by mass, more particularly from 90% to 100% by mass, and preferably from 95% to 100% by mass, of the total mass of the base oil(s) of the composition containing it(them). In a particular embodiment, a lubricating composition according to the invention is completely free of base oil distinct from the re-refined lubricating oil(s)^).

[0203] Additives

[0204] In a particular embodiment, a 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.

[0205] 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.

[0206] Preferably, the composition comprises one or more additives selected from viscosity index improvers, pour point depressant additives, anti-wear additives, antioxidants and mixtures thereof.

[0207] 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 properties of the composition based on the said re-refined lubricating oil(s) are not or are not substantially altered by the envisaged addition.

[0208] In particular, the composition may comprise from 0% to 20% by mass, in particular from 0.01% to 10% by mass, of additives, in particular as described above, relative to the total weight of the composition.

[0209] In particular, the composition may comprise from 80% to 99.95% by mass, preferably from 80% to 99.99% by mass, of at least one base oil consisting of at least one at least partly re-refined lubricating oil and, optionally, new lubricating oil, and from 0.01% to 20% by mass, and preferably from 0.05% to 10% by mass of additives, relative to the total weight of the composition.

[0210] The invention thus relates, according to another of its aspects, to a process or method for preparing a lubricating composition, comprising at least one step consisting of obtaining a lubricating oil at least partly re-refined from a used lubricant.

[0211] Preferably, such a method or process comprises at least the steps of:

[0212] (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 passage of the used lubricant over an adsorbent material, preferably as detailed previously;

[0213] (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

[0214] (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.

[0215] Applications

[0216] A lubricating oil that is at least partly re-refined is particularly suitable for use in a lubricating composition.

[0217] As previously indicated, the use of re-refined oils, preferably whose characteristics are equivalent to those defined by the API classification for Group I or Group II base oils, advantageously makes it possible to reduce the wear of parts, in particular the wear of moving parts, and more particularly to reduce pitting by mechanical fatigue of moving parts in a mechanical system.

[0218] In particular, the mechanical system may be a mobile or stationary motorization system.

[0219] 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.

[0220] 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.

[0221] 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.

[0222] 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.

[0223] For the purposes of the present invention, the term "propulsion system" means a system comprising the mechanical parts necessary for the propulsion of a vehicle. The propulsion system more particularly includes 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.

[0224] 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.

[0225] The re-refined oils according to the invention can be used in a composition for lubricating the various parts of a propulsion system of an electric or hybrid vehicle, in particular the engine, the power electrics, the transmission and / or the battery, more particularly the bearings located between the rotor and the stator of an electric motor, or even the transmission, in particular the reducer, in an electric or hybrid vehicle.

[0226] More particularly, they can be used to lubricate an electric motor of an electric or hybrid vehicle. They also provide lubrication of the bearings located between the rotor and the stator of an electric motor of an electric or hybrid vehicle. In particular, a composition based on at least one re-refined oil used according to the invention makes it possible to provide lubrication of the transmission, when present, in particular the reducer, of an electric or hybrid vehicle.

[0227] Thus, advantageously, it is for example possible, by using a composition based on at least one re-refined oil used according to the invention, to ensure the lubrication of the transmission, in particular the reducer, in an electric or hybrid vehicle.

[0228] The invention relates in particular to a method or process for reducing wear of parts in a mechanical system, in particular pitting by mechanical fatigue of moving parts in a mechanical system, comprising at least one step of circulating at said mechanical system a composition based on at least one at least partly re-refined lubricating oil, in particular as described above. Such a method or process comprises in particular the steps consisting of: a) providing a composition based on at least one at least partly re-refined lubricating oil, in particular as defined above; b) implementing said composition of step a) at a mechanical system, in particular as described above; and c) circulating said composition at said mechanical system.

[0229] 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.

[0230] The invention will now be described by means of the following examples, given by way of illustration and not limitation of the invention.

[0231] Examples

[0232] The methods for measuring the various parameters indicated in the examples are detailed below.

[0233] Method for measuring kinematic viscosity The kinematic viscosity of oils is measured at 40°C (KV40) and at 100°C (KV 100) 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).

[0234] Method of measuring viscosity index

[0235] The viscosity index is a dimensionless ratio that gives 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 EN ISO 2909. The higher the index, the less the viscosity of oils is influenced by temperature variations.

[0236] Method for measuring sulfur and aromatic compound content

[0237] The sulfur and aromatic compound contents in the oil are determined by infrared or ultraviolet spectroscopy.

[0238] Method of measuring acid number

[0239] The acid number, also called Acid Number (AN) and formerly Total Acid Number (TAN), is by definition the number of milligrams of potash necessary to neutralize the organic or mineral acids contained in one gram of oil (mg KOH / g).

[0240] The measurement of the acid number is carried out by the potentiometric titration method ASTM D 664 (11 / 2018, Edition 5) for new and used oils.

[0241] Pour point measurement method

[0242] The pour point of compositions is measured according to ASTM D5950 and is expressed in degrees Celsius.

[0243] Volatility measurement method

[0244] 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.

[0245] Method of measuring density

[0246] 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 / m 3 .

[0247] Method of measuring thermal conductivity

[0248] Thermal conductivity, often denoted by λ, characterizes the oil's ability to diffuse heat into the environment. It is measured by a transient hot-wire liquid thermal conductivity method, according to ASTM D7896-19. It is expressed in mW / niK.

[0249] Flash point measurement method

[0250] The flash point provides an indication of a product's ability 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.

[0251] Measurement of pitting by mechanical fatigue

[0252] Pitting by mechanical fatigue (or “pitting” in Anglo-Saxon) is assessed by a test on an MPR tribometer (for “Micro Pitting Rig” in Anglo-Saxon).

[0253] The MPR tribometer is a machine that places a central roller (diameter 12 mm) in contact with three rings (diameter 54 mm) arranged around the roller. This geometric configuration allows the test roller to be subjected to a large number of rolling contact cycles over a short test period, which promotes pitting by mechanical fatigue.

[0254] Fatigue pitting is detected using an accelerometer connected to a vibration monitor. When the vibration setpoint is exceeded due to the occurrence of pitting, the test is stopped. For each composition, the test is carried out two to three times. The duration of each test until the vibration setpoint is reached is recorded. The longer the test duration, i.e. the longer it takes to reach the vibration setpoint, the higher the performance in terms of mechanical fatigue pitting of the tested compositions.

[0255] Example 1

[0256] The properties of lubricating compositions II and 12 comprising an at least partly re-refined oil H, in accordance with the invention and commercially available, were evaluated.

[0257] The properties of another lubricating composition 13 comprising an at least partly re-refined oil J, in accordance with the invention and commercially available, were also evaluated.

[0258] The at least partly re-refined H oil is obtained from used lubricating compositions (comprising a significant proportion of base oil in their composition) which have 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.

[0259] The at least partly re-refined J oil is obtained from used lubricating compositions (comprising a significant proportion of base oil in their composition) which have 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.

[0260] A lubricant composition Cl based on new / native base oil only, not in accordance with the invention because it has not undergone any recycling or re-refining step, was also evaluated. This composition comprises a commercially available API group I base oil.

[0261] Composition II comprises 25% new / native oil and 75% H oil as defined above.

[0262] Composition 12 is free of new oil and therefore only comprises H oil as defined above. Composition 13 comprises 25% new / native oil and 75% J oil as defined above.

[0263] The kinematic viscosity at 40°C and 100°C, viscosity index, density at 15°C, Noack volatility and Cleveland flash point of H and J oils were measured according to the protocols detailed above. The results are presented in Table 2 below.

[0264] [Table 2]

[0265] The kinematic viscosity at 40 °C and 100 °C, viscosity index, sulfur content, acid number, and pour point of these compositions Cl, II, 12 and 13 were measured according to the protocols detailed above. The results are presented in Table

[0266] 3 below.

[0267] [Table 3] The mechanical fatigue pitting performance of the compositions was tested according to the previously described mechanical fatigue pitting measurement test. The results are shown in Table 4 below. [Table 4]

[0268] It is observed that the re-refined lubricating oils according to the invention exhibit, in a lubricating composition, a performance in pitting by mechanical fatigue which is equivalent or even very significantly improved compared to an equivalent new lubricating oil.

[0269] In particular, results equivalent to those obtained with the reference composition C1 were obtained using composition II according to the invention. In addition, surprising results were obtained using composition 12 according to the invention, this composition being free of new oil. Thus, for composition 12, the test systematically reaches the end of the maximum test duration set (750 hours) for the three tests.

[0270] Similarly, with a re-refined lubricating oil of a different nature from that introduced in II and 12 (and present at a content of 75% by weight relative to the total weight of oil integrated into the lubricating composition 13), the composition 13 offers even more surprising results with a maximum test duration increasing to 2750 h on average, and this in the absence of a maximum threshold fixed this time.

Claims

Claims 1. Use of at least one at least partly re-refined lubricating oil for reducing wear of parts in a mechanical system, in particular wear of moving parts in a mechanical system.

2. Use according to claim 1, for reducing pitting by mechanical fatigue of moving parts in a mechanical system.

3. Use according to any one of the preceding claims, said at least partly re-refined lubricating oil(s) originating 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.

4. Use according to any one of the preceding claims, said at least partly re-refined lubricating oil(s) being used in a composition in a content of at least 50% by mass, in particular at least 70% by mass, in particular at least 75% by mass, and more particularly at least 80% by mass, relative to the total mass of said composition.

5. Use according to any one of the preceding claims, said at least partly re-refined lubricating oil(s) having a kinematic viscosity, measured at 100°C according to standard ASTM D445, greater than or equal to 4.0 mm 2 / s, notably varying from 4.0 to 12 mm 2 / s, in particular greater than or equal to 4.3 mm 2 / s and more particularly varying from 4.4 to 10 mm 2 / s, especially from 5.0 to 6.5 mm 2 / s.

6. Use according to any one of the preceding claims, said at least partly re-refined lubricating oil(s) having a viscosity index greater than or equal to 110, in particular varying from 110 to 130, in particular from 115 to 125.

7. Use according to any one of the preceding claims, said at least partly re-refined lubricating oil(s) having a Noack volatility strictly less than 12%, in particular ranging from 5% to 12%, and more particularly ranging from 6% to 11.5%.

8. Use according to any one of the preceding claims, said at least partly re-refined lubricating oil(s) having a sulfur content ranging from 0.001% to 0.2% by mass, in particular from 0.01% to 0.2% by mass relative to the total mass of said regenerated lubricating oil.

9. Use according to any one of the preceding claims, said at least partly re-refined lubricating oil(s) having a content of aromatic compound(s) greater than or equal to 0.01% by mass, more particularly ranging from 0.02% to 10% by mass, relative to the total mass of said regenerated lubricating oil.

10. Use according to any one of the preceding claims, said at least partly re-refined lubricating oil(s) having a density less than or equal to 870 kg / m 3 , in particular ranging from 830 to 870 kg / m 3 , in particular less than or equal to 860 kg / m 3 , and more particularly ranging from 840 to 860 kg / m 3 .

11. Use according to any one of the preceding claims, said at least partly re-refined lubricating oil(s) having an alkylphenol(s) content ranging from 5 to 3,200 ppm, in particular from 10 to 2,000 ppm, preferably from 15 to 1,500 ppm.

12. Use according to any one of the preceding claims, said at least partly re-refined lubricating oil(s) comprising one or more polyalphaolefins (PAO) comprising less than 40 carbon atoms, and preferably comprising 30 carbon atoms.

13. Use according to any one of the preceding claims, said at least partly re-refined lubricating oil(s) being used in a composition comprising 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, viscosity index (VI) improvers, pour point depressants (PPD), dispersants, anti-foaming agents, and mixtures thereof.

14. Use of at least one lubricating composition comprising at least one at least partly re-refined lubricating oil, in particular as defined in any one of claims 3 to 12, for reducing wear of parts in a mechanical system, in particular wear of moving parts in a mechanical system, and more particularly for reducing pitting by mechanical fatigue of moving parts in a mechanical system.

15. Method for reducing wear of parts in a mechanical system, in particular pitting by mechanical fatigue of moving parts in a mechanical system, comprising at least one step of putting into circulation at said mechanical system of a composition based on at least one at least partly re-refined lubricating oil, in particular as defined in any one of claims 3 to 12.

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