Lubricating composition comprising a re-refined lubricating oil and a spiro compound

Abstract

Lubricating Composition Comprising a Re-Refined Lubricating Oil and a Spiro Compound. This application relates to a lubricating composition, in particular for preventing and / or reducing deposits in a powertrain lubricated by means of the lubricating composition, which comprises at least: a lubricating oil, at least partially re-refined; and a spiro compound of the following formula (I), in which: M is an atom selected from boron and aluminum; n1 and n2 are, independently of each other, 0, 1, 2, 3, or 4; and R represents, independently of each other, a hydrocarbon group comprising from 1 to 50 carbon atoms. It also relates to the use of such a lubricating composition for preventing and / or reducing deposits in a powertrain lubricated by means of said lubricating composition, in particular in an internal combustion engine. Figure for abstract: None

Description

Title of the invention: Lubricating composition comprising a re-refined lubricating oil and a spiro compound Technical field

[0001] The present invention relates to the field of lubricating compositions, in particular usable in mechanical systems, such as motorization systems, in particular for the lubrication of internal combustion engines.

[0002] More particularly, the present invention provides new lubricating compositions which, when used, provide good detergency properties, in particular by preventing and / or reducing deposits in an engine system. Prior art

[0003] Lubricating compositions, also called "lubricants", are commonly used in the various components of motor vehicles for the main purpose of reducing the 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 with which are generally associated several additives dedicated to stimulating the lubricating performance of the base oil, for example friction modifying additives, but also to providing additional performance.

[0004] In fact, lubricants intended for the lubrication of engines, for example diesel engines, must meet several requirements. They must therefore combine good anti-wear and anti-corrosion performance, as well as good detergency and dispersion properties to reduce the formation of deposits.

[0005] In particular, it is essential that lubricants, especially for gasoline, diesel, gas (liquefied, compressed or hydrogen) or dual fuel engines, have good detergency properties. In fact, incomplete combustion of the fuel produces soot which can lead to sludge deposits, as well as carbon and varnish deposits. In the case of diesel or gasoline fuels, the residual sulfur in the fuel burns in the combustion chamber to produce sulfur-derived acids. These acids are responsible for corrosion and wear in the engine and accelerate the degradation of the oil.

[0006] Detergent additives are thus added to base oils to prevent the formation of deposits on the surface of metal parts, which are harmful to the engine, by dissolving the oxidation and combustion by-products, and thus increase engine life. Commonly used detergent additives are metal salts, including sulfonates, phenates, and salicylates of alkali metals, particularly calcium or magnesium, whether overbased or not. However, these metal detergents generate ash, including sulfated ash, as well as phosphorus and sulfur, which are known to damage the exhaust gas aftertreatment systems that are now fitted to all new vehicles to eliminate harmful emissions such as NOx, CO, or soot. Furthermore, existing and proposed environmental emissions regulations require manufacturers to develop increasingly efficient exhaust gas aftertreatment systems.

[0007] Therefore, research has been directed towards the development of new low ash detergent compounds.

[0008] Applications WO / 2023057590 and WO / 2023057586 propose, for example, the use of spiroboronate compounds as a detergent additive in a lubricating oil, as an alternative to the metallic detergents commonly used previously.

[0009] It is also accepted that the effectiveness of a detergent additive within a lubricating composition depends on the quality of the base oils into which the detergent additive is introduced.

[0010] Current environmental concerns, particularly with a view to reducing carbon dioxide emissions, also lead to an urgent need for lubricating compositions with a reduced carbon footprint. However, it is essential that these compositions with a reduced carbon footprint have technical performances that are at least equivalent to, or even superior to, the compositions used to date.

[0011] There is therefore a need to have lubricating compositions for engine systems, having a reduced carbon footprint, while having optimized detergency properties.

[0012] The present invention aims precisely to meet these needs. Statement of the invention

[0013] According to a first aspect, the present invention relates to a lubricating composition comprising at least:

[0014] i. an at least partly re-refined lubricating oil; and

[0015] ii. a spiro compound of the following formula (I):

[0016] [Chem.l]

[0017] in which:

[0018] M is an atony chosen from boron and aluminum;

[0019] ni and n2 are, independently of each other, 0, 1, 2, 3 or 4, and

[0020] R represent, independently of one another, a hydrocarbon group comprising from 1 to 50 carbon atoms.

[0021] In the remainder of the text, the term “lubricating composition” or “lubricant” according to the invention will refer to a lubricating composition as defined above.

[0022] 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 re-refining treatment steps.

[0023] 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.

[0024] 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”.

[0025] Due to their origin, used lubricating oils, in particular engine lubricating oils, include a number of degradation products derived from the oil itself or from the additives it contains, as well as metal particles, metal oxides and other elements, for example from the engine. A used oil may contain in particular a high content of undesirable elements, for example calcium (Ca), iron (Fe), magnesium (Mg), sodium (Na), nickel (Ni), phosphorus (P), silicon (Si), chlorine (Cl), zinc (Zn), oxygen (O), or nitrogen (N), etc.

[0026] Methods for re-refining or reconditioning used lubricating oils have been developed to regenerate these oils and allow their subsequent reuse.

[0027] 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.

[0028] In the remainder of the text, a spiro compound of formula (I) as defined above will also be referred to as a "spiro compound" according to the invention. Examples of spiro compounds considered according to the invention are described in more detail in the remainder of the text.

[0029] It is noted that the spiro compounds of formula (I) as defined above are used as detergent additives and, optionally, as antioxidant additives, in particular for controlling deposits or oxidation in a mechanical system.

[0030] Surprisingly, as illustrated in the examples which follow, the inventors have discovered that the formulation of a spiro compound of formula (I) in combination with at least one at least partly re-refined lubricating oil advantageously allows a potentiation of the detergency efficiency compared to the formulation of the spiro compound at the level of a virgin base oil.

[0031] These detergency properties, in particular in terms of prevention and / or reduction of deposits, can be evaluated by implementing the conditions of the test detailed in the section “Measurement of detergency properties”, corresponding to a TDI3 engine test carried out according to the CEC L1 17-20 method, measuring in particular the cleanliness of the pistons defining engine cleanliness.

[0032] Advantageously, as described in Example 2 below, the use of the spiro compound in association with a re-refined lubricating oil thus makes it possible to achieve values ​​in terms of detergency efficiency which are particularly high and, to the inventors' knowledge, never achieved with the detergency additives usually used at the level of native base oils (also called virgin or new oils).

[0033] As explained in detail below, the composition of re-refined oils differs from that of virgin base oils, in particular by the presence of degradation products. It was therefore by no means obvious to the inventors that the use of the spiro compound in re-refined oils could exacerbate the detergency efficiency, especially since it is usually sought to formulate the additives in quality base oils.

[0034] The lubricating compositions according to the invention advantageously have a reduced carbon footprint, compared to oil-based lubricating compositions. virgin, in that they are prepared from recycled oils.

[0035] The inventors have further discovered that, advantageously, the use of a spiro compound of formula (I), as defined above, in combination with re-refined lubricating oils makes it possible to obtain a lubricating composition having excellent antioxidant properties, in particular improved antioxidant efficiency compared to the antioxidant properties achieved when the spiro compound is formulated within virgin base oils.

[0036] These antioxidant properties, highlighted in example 3 below, can for example be evaluated under the conditions described in the test detailed in the section “Measurement of oxidation stability”, corresponding to a standard procedure in the lubricating oil industry based on the CEC L-85 T-99 standard.

[0037] According to another aspect, the present invention relates to the use in a lubricating composition of at least one spiro compound of formula (I) in combination with at least one re-refined lubricating oil as defined above, to improve the detergency properties of said lubricating composition intended for a powertrain system, in particular an internal combustion engine, in particular to prevent and / or reduce deposits in said powertrain system lubricated by means of said lubricating composition.

[0038] In particular, the invention relates to the use in a lubricating composition of at least one spiro compound of formula (I) in combination with at least one re-refined lubricating oil, as defined above, to simultaneously improve the detergency properties and the antioxidant properties of said lubricating composition intended for a powertrain system, in particular an internal combustion engine, in particular to prevent and / or reduce deposits in said powertrain system lubricated by means of said lubricating composition.

[0039] According to another aspect, the present invention relates to the use of a lubricating composition as defined above, for preventing and / or reducing deposits in an engine system lubricated by means of said lubricating composition, in particular in an internal combustion engine.

[0040] The invention also relates to a method or process for preventing and / or reducing deposits in a powertrain system, in particular in an internal combustion engine, comprising the lubrication of said powertrain system with a lubricating composition according to the invention. Such a system comprises, in particular, an engine, for example an internal combustion engine and / or a mechanical transmission member.

[0041] Said method or process more particularly comprises a step of bringing at least one mechanical part of said motorization system, for example a mechanical part of an internal combustion engine, into contact with a com- lubricating position according to the invention as defined previously.

[0042] Other characteristics, variants and advantages of the lubricating compositions 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.

[0043] The expressions “between ... and ...”, “ranging from ... to ...”, “formed from ... to ...”, and “varying from ... to ...”, must be understood inclusively, unless otherwise stated.

[0044] The expression "at least one" is equivalent to "one or more" and, unless otherwise indicated, the limits of a domain of values ​​are included in this domain.

[0045] In the description and examples, unless otherwise indicated, the percentages are weight percentages. The percentages are therefore expressed by mass relative to the total mass of the composition. The temperature is expressed in degrees Celsius unless otherwise indicated, and the pressure is atmospheric pressure, unless otherwise indicated. Detailed description Lubricating oil at least partly re-refined

[0046] As indicated previously, a lubricating composition according to the invention comprises at least one lubricating oil that is at least partly re-refined, also called “regenerated oil” or “recycled oil”, in other words an oil originating at least partly from a used lubricating composition that has been subjected to one or more re-refining treatment steps.

[0047] It is understood that a used lubricating composition may be a mixture of several used lubricating compositions, originating from the same source or from several different sources.

[0048] 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.

[0049] It may be a mixture of several base oils, for example a mixture of two, three, or four base oils.

[0050] 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.

[0051] 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.

[0052] [Tables 1] Saturates content Sulphur content Viscosity index (VI) Group I Mineral oils < 90% > 0.03% 80 <VI< 120 Groupement II Huiles hydrocraquées > 90% <0.03% 80 <VI < 120 Groupement III Huiles hydrocraquées ou hydro-isomérisées >90% <0.03% >120 Group IV Polyalphaolefins (PAO) Group V Esters and other bases not included in groups I to IV

[0053] In particular, the used lubricating composition, from which the regenerated lubricating oil used in lubricating compositions according to the invention is derived, may comprise at least 50% by mass of base oil(s) relative to its total mass, in particular at least 60% by mass of base oil(s), and more particularly between 60 and 99% by mass of base oil(s).

[0054] According to a particular embodiment, the re-refined lubricating oil used in lubricating compositions according to the invention may be obtained from the treatment of a used lubricating composition having been used for the lubrication of a motorization system, in particular a “mobile” system, i.e. including light vehicles, heavy goods vehicles, or even so-called “off-road” mobile machines.

[0055] According to another particular embodiment, the re-refined lubricating oil used in lubricating compositions 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.

[0056] A used lubricating composition, from which the regenerated lubricating oil used in lubricating compositions according to the invention is derived, may contain different conventional additives in the field of lubricants, such as friction modifier additives, extreme pressure additives, anti-wear additives, detergents other than spiro compounds of formula (I) as defined above, antioxidants, viscosity index (VI) improvers, pour point depressant (PPD) additives, dispersing agents, anti-foaming agents, thickeners, and mixtures thereof.

[0057] As already mentioned previously, the properties of the used lubricating composition are degraded due to its use, for a more or less long period, for the lubrication and / or cooling of a mechanical system, in particular a motorization system, such as a combustion engine.

[0058] 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.

[0059] The composition of used lubricating compositions may of course be different depending on the origin of the lubricating compositions, their initial formulation and the fact that they may have been contaminated differently depending on their use.

[0060] The regenerated lubricating oil used in lubricating compositions 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.

[0061] In particular, these treatment steps aim to eliminate, at least partially, water, solid particles, fuel and / or other contaminants, such as polycyclic aromatic hydrocarbons (PAHs), which are undesirable in the formulation of lubricants.

[0062] According to a particular embodiment, the at least partly re-refined lubricating oil, used in lubricating compositions 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.

[0063] Preferably, the regenerated lubricating oil used in lubricating compositions 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.

[0064] Advantageously, the at least partly re-refined lubricating oil, in other words the regenerated lubricating oil, used in lubricating compositions according to the invention, thus comprises a water content of less than or equal to 10% by mass, in 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 lubricating oil at least partly re-refined.

[0065] 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.

[0066] 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.

[0067] Preferably, the at least partly re-refined lubricating oil used in lubricating compositions 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.

[0068] Preferably, the at least partly re-refined lubricating oil used in lubricating compositions 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 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 may 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.

[0069] Advantageously, the at least partly re-refined lubricating oil, used in lubricating compositions 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.

[0070] The adsorbent material advantageously makes it possible to selectively adsorb aromatic compounds, in particular PAHs.

[0071] In particular, the passage over an adsorbent material, preferably over activated carbon, advantageously makes it possible to reduce the content of polycyclic aromatic hydrocarbons (PAHs), in particular 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 lu- composition used grinder.

[0072] The term “passage of the used lubricating composition over an adsorbent material” means the flow of the used lubricating composition over the adsorbent support.

[0073] The adsorbent materials may be, for example, activated carbon, zeolites, clays or functionalized porous compounds. Preferably, it is activated carbon.

[0074] For example, the at least partly re-refined lubricating oil, used in lubricating compositions 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.

[0075] 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.

[0076] The flow rate of the used lubricating composition may be between 1 m3 / h and 15 m3 / h, for example between 5 and 10 m3 / h.

[0077] Preferably, the activated carbon is characterized by a density of between 200 and 500 kg / m3, for example measured according to the ASTDM D2854 standard.

[0078] Preferably, the activated carbon is a coal, preferably comprising from 70 to 95%, advantageously from 80 to 90% by mass of carbon.

[0079] The step of passing the used lubricating composition onto an adsorbent support, preferably onto activated carbon, is advantageously preceded by the following preliminary steps: - one or more distillation stages; and - a filtration step, in particular as defined previously.

[0080] Advantageously, the at least partly re-refined lubricating oil can be obtained by subjecting a used lubricating composition to at least one prior hydrogenation (or hydrotreatment) step, preferably following 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 used lubricating composition 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.

[0081] Advantageously, the at least partly re-refined lubricating oil 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 used lubricating composition of dark color, 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.

[0082] Advantageously, the at least partially re-refined lubricating oil 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.

[0083] It is understood that the invention is in no way limited to regenerated lubricating oils obtained according to the treatment methods described above. Other at least partly re-refined lubricating oils, resulting from treatment steps different from those described above, may be suitable for the invention.

[0084] In any event, a re-refined lubricating oil used according to the invention is distinguished from a used lubricating composition, in particular 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.

[0085] On the other hand, a regenerated lubricating oil used according to the invention is distinguished, due to its formation from a used lubricating composition, 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.

[0086] According to a particular embodiment, the re-refined lubricating oil(s) used in compositions according to the invention have(s) a kinematic viscosity measured at 40°C according to the ASTM D445 standard, greater than or equal to 20 mm2 / s and more particularly between 20 and 40 mm2 / s, in particular between 25 and 35 mm2 / s.

[0087] According to a particular embodiment, the re-refined lubricating oil or oils have a kinematic viscosity measured at 100°C according to the ASTM D445 standard greater than or equal to 3.0 mm2 / s, in particular greater than or equal to 4.0 mm2 / s, in particular between 4.0 and 12 mm2 / s, in particular greater than or equal to 4.3 mm2 / s and more particularly between 4.4 and 10 mm2 / s, in particular between 4.5 and 6 mm2 / s.

[0088] According to one embodiment, the re-refined lubricating oil or oils have a viscosity index, determined according to the ASTM D2270 standard, greater than or equal to 110, in particular between 110 and 130, preferably between 112 and 125, and more particularly between 118 and 124.

[0089] The viscosity index is calculated by measuring the kinematic viscosity at 40°C and 100°C. These measurements are then compared to the results of two reference oils. Its calculation method is described in ASTM D2270.

[0090] According to a particular embodiment, the re-refined lubricating oil or oils have a sulfur content of between 0.01% and 0.2% by mass, relative to the total mass of said at least partly regenerated lubricating oil.

[0091] According to a particular embodiment, the re-refined lubricating oil(s) have(s) 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 15% by mass, relative to the total mass of said re-refined lubricating oil(s).

[0092] The contents of these different elements can be determined according to any method known to those skilled in the art, for example by X-ray fluorescence (XRF) or by infrared or ultraviolet spectroscopy.

[0093] In a particular embodiment, in the lubricating composition according to the invention, said at least partly re-refined lubricating oil(s) represent more than 10% by mass, in particular more than 20% by mass, more particularly more than 30% by mass, in particular more than 40% by mass, of the total mass of the lubricating composition.

[0094] According to a particular embodiment, the mass content of at least partly re-refined lubricating oil(s) is at least 50% by mass of the total mass of the lubricating composition, in particular at least 60% by mass, in particular at least 70% by mass and more particularly between 75% and 85% by mass relative to the total mass of said lubricating composition.

[0095] As detailed in the remainder of the text, said re-refined lubricating oil(s) may be used as the sole base oil(s), in other words, without the addition of a separate base oil, for example new base oil. Alternatively, they may be used in combination with at least one new base oil.

[0096] In a particular embodiment, the lubricating composition thus further comprises one or more base oils distinct from said at least partly re-refined lubricating oil(s), in particular one or more new base oils.

[0097] These new base oils can be chosen in particular from oils of bases conventionally used in the field of lubricants, such as mineral, synthetic or natural, animal or vegetable oils or their mixtures.

[0098] 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.

[0099] 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.

[0100] In particular, the at least partly re-refined lubricating oil(s) may represent at least 10% by mass, in particular at least 20% by mass, notably at least 30% by mass and more particularly at least 40% by mass, of the total mass of lubricating oils in the lubricating composition.

[0101] In a particular embodiment, said at least partly re-refined lubricating oil(s) may represent more than 50% by mass of the total mass of lubricating oils, in particular at least 60% by mass, in particular more than 70% by mass, more particularly more than 80% by mass, in particular more than 90% by mass, or even 100% of the total mass of lubricating oils in the lubricating composition.

[0102] In a particular embodiment, a lubricating composition according to the invention is completely free of base oil other than re-refined lubricating oils. Spiro compound

[0103] In the context of the invention, the following terms are understood to mean:

[0104] - “hydrocarbon group”, a saturated or unsaturated radical, linear, branched or cyclic, aromatic or not, comprising carbon and hydrogen;

[0105] - “aliphatic chain”, a hydrocarbon group consisting exclusively of atoms of carbon and hydrogen, linear or branched, saturated or unsaturated, non-aromatic. Preferably, an aliphatic chain is an alkyl chain;

[0106] - “alkyl”, a saturated, linear or branched aliphatic group; for example, an alkyl in Cx to Cz represents a saturated carbon chain of x to z carbon atoms, linear or branched; - “alkenyl”, a mono- or poly-unsaturated aliphatic group, linear or branched;

[0107] - “cycloalkyl”, a cyclic alkyl group, for example a Cx to Cz cycloalkyl represents a cyclic carbon group of x to z carbon atoms, for example cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl;

[0108] - “aryl”, a mono- or polycyclic aromatic group, in particular comprising between 6 and 10 carbon atoms. Examples of aryl groups include phenyl or naphthyl groups;

[0109] - “aralkyl”, an aryl group as defined above, substituted by at least an alkyl group as defined above.

[0110] As indicated previously, a lubricating composition according to the invention comprises at least one spiro compound of formula (I) as defined previously.

[0111] As mentioned previously, the spiro compound considered according to the invention is of the following formula (I):

[0112] [Chem.2]

[0113] in which: M is an atom selected from boron and aluminum, in particular is a boron atom; ni and n2 are, independently of each other, 0, 1, 2, 3 or 4; and R represent, independently of one another, a hydrocarbon group comprising from 1 to 50 carbon atoms, in particular from 5 to 15 carbon atoms.

[0114] The hydrocarbon groups considered according to the invention may optionally be interrupted by one or more heteroatoms, for example -O-, -NH-, -N= or -S-, in particular -O- or -NH-; and / or optionally substituted by one or more -OH, -NH2 and -SH groups, in particular -OH or -NH2.

[0115] According to a particular embodiment, the R groups are composed solely of carbon and hydrogen atoms.

[0116] The hydrocarbon groups may in particular be alkyl, alkenyl, aryl or aralkyl groups.

[0117] According to a particular embodiment, the substituents R represent, independently of one another, a hydrocarbon group, preferably an aliphatic chain, linear or branched, comprising from 3 to 50 carbon atoms, in particular from 3 to 30 carbon atoms, in particular from 5 to 25 carbon atoms and more particularly from 8 to 15 carbon atoms.

[0118] In particular, the substituents R may represent, independently of one another, a linear or branched aliphatic chain, in particular an alkyl chain, preferably linear, from C1 to C50, in particular from C3 to C30, in particular from C5 to C25, more particularly from C8 to C15, more preferably from C14.

[0119] According to a particular embodiment, ni and n2 are equal to 0.

[0120] According to another particular embodiment, n1 and n2 are equal to 1 or 2.

[0121] When ni is 2 or n2 is 2, the R groups, carried by the same cycle, may be the same or different.

[0122] According to a particular embodiment, the spiro compound may be of formula (I) above, in which n1 and n2 are 1; the substituents R may be identical or different, preferably identical.

[0123] According to a particular embodiment, the spiro compound is of formula (I) above, in which: ni and n2 are 1; and the R groups, which are identical, represent alkyl groups, preferably linear, from C1 to C50, in particular from C3 to C30, in particular from C5 to C23 and more particularly from C8 to C15.

[0124] According to a particular embodiment, the spiro compound is of formula (I) in which M is a boron atom.

[0125] In other words, according to this particular embodiment, the spiro compound can be a so-called spiroboronate compound, of the following formula (!):

[0126] [Chem.3]

[0127] in which ni and n2 and R are as defined previously.

[0128] For example, the spiro compound may be of formula (!') in which n1 and n2 are 1 and R is a linear C14 alkyl group.

[0129] According to another particular embodiment, the spiro compound is of formula (I) in which M is an aluminum atom.

[0130] In other words, according to this particular embodiment, the spiro compound can be a so-called spiroaluminate compound, of the following formula (I”):

[0131] [Chem.4]

[0132] in which ni, n2 and R are as defined previously.

[0133] The invention thus relates, according to another of its aspects, to a spiro compound of formula (I) above, in which: - M is an aluminum atom; - ni and n2 are, independently of each other, 0, 1 or 2, at least one of ni and n2 being 1 or 2; preferably ni and n2 are 1; - the R groups represent, independently of one another, an aliphatic chain, linear or branched, in particular an alkyl chain, preferably linear, in C5 to C5o, in particular in C6 to C30, in particular in C8 to C2s and more particularly in C10 to C15.

[0134] In other words, the invention relates to a spiroaluminate type compound of formula (I”) above, in which: - ni and n2 are, independently of each other, 0, 1 or 2, at least one of ni and n2 being 1 or 2; preferably ni and n2 are 1; and - the R groups represent, independently of one another, an aliphatic chain, linear or branched, in particular an alkyl chain, preferably linear, in C5 to C5o, in particular in C6 to C30, in particular in C8 to C23 and more particularly in Cio to C15.

[0135] According to a particular embodiment, the spiroaluminate type compound according to the invention is of formula (I”) in which: - ni and n2 are equal to 1; and - the R groups, identical or different, preferably identical, represent alkyl chains, preferably linear, in C5 to C50, in particular in C6 to C30, in particular in C8 to C25 and more particularly in C10 to C15.

[0136] The spiro compound used according to the invention can be prepared from at least salicylic acid or a salicylic acid derivative and a boron compound or an aluminum compound.

[0137] More particularly, it can be obtained by reaction: - at least one compound chosen from salicylic acid and its derivatives, of the following formula (Ia):

[0138] [Chem.5] (there)

[0139] in which R is as defined previously and n3 is as defined previously for n1 and n2; and - at least one boron or aluminum compound, in particular boric acid or aluminum hydroxide.

[0140] The preparation of the spiro compound used in the lubricating composition according to the invention does not involve any step, subsequent to the reaction of salicylic acid or one of its derivatives with said boron or aluminum compound, of reaction with an amine compound, as is the case for example in the context of the preparation of the compounds proposed in applications WO2018 / 220007 and WO2018 / 220009.

[0141] Salicylic acid and its derivatives of formula (Ia) above can be synthesized according to synthesis methods known to those skilled in the art or be commercially available.

[0142] The boron compound (in other words, boron-based) may be chosen in particular from boric acid (B(OH)3), boronic acids, boric and boronic esters, boron oxide and boric acid complexes.

[0143] In particular, the boron compound may be chosen from boric acid; boron oxide; boric acid complexes; trialkyl borates, in particular in which the alkyl groups comprise, independently of one another, from 1 to 4 carbon atoms; boronic acids having a C1 to C12 alkyl group; boric acids substituted by two alkyl groups, in particular C1 to C12; boric acids substituted by two aryl groups, in particular C6 to C12; boric acids substituted by one or two aralkyl groups, in particular C7 to C12, and derivatives of these compounds obtained by substitution of at least one alkyl group by one or more alkoxy groups.

[0144] Boric acid complexes are in particular complexes of boron with one or more molecules comprising one or more alcohol functions.

[0145] According to a particular embodiment, the boron compound is boric acid.

[0146] The aluminum compound (in other words, aluminum-based) may be chosen, for example, from aluminum hydroxide (A1(OH)3), aluminum oxide, aluminum sulfate aluminum (A12SO4)3.

[0147] It is up to the person skilled in the art to adjust the reaction conditions between said compound(s) (Ia) and the boron or aluminum compound to obtain the desired spiro compound.

[0148] In particular, the reaction can be carried out in a solvent medium consisting of one or more apolar solvents and / or protic polar solvents.

[0149] The solvent medium may consist of one or more solvents chosen from naphtha, protic polar solvents, such as water and alcohols, for example methanol, ethanol, propanol, butanol; and mixtures thereof.

[0150] Advantageously, the reaction between salicylic acid or one of its derivatives of formula (Ia) above and the boron or aluminum compound to obtain the desired spiro compound, in particular the reaction between salicylic acid or one of its derivatives of formula (Ia) and the boron compound to obtain the desired spiroboronate compound, can be carried out in an apolar aprotic solvent medium, in particular in toluene.

[0151] According to one embodiment, one or more spiro compounds of formula (I) are used in a content of between 0.05% and 15% by mass relative to the total mass of the lubricating composition, in particular of between 0.1% and 10% by mass, more particularly of between 1% and 5% by mass relative to the total mass of the lubricating composition. Other Additives

[0152] A lubricating composition 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, off-road vehicles, in particular in combustion engine systems.

[0153] These additives, distinct from the spiro compound(s) defined above, may in particular be chosen from friction modifying additives, antiwear additives, extreme pressure additives, additional detergents, basic organic additives improving the total base number (TBN), antioxidants, viscosity index (VI) improvers, pour point depressant (PPD) additives, dispersants, antifoaming agents, thickeners, corrosion inhibitors, copper passivating agents, and mixtures thereof.

[0154] These additives can be introduced in isolation and / or in the form of a mixture, or “additive package”, similar to those already available for sale for commercial lubricant formulations.

[0155] Advantageously, a lubricating composition according to the invention may comprise one or more additives chosen from viscosity index improvers, additives pour point depressants, anti-wear additives, antioxidants and their mixtures.

[0156] These additives may be added to said at least partly re-refined lubricating oil(s) or to the mixture of said at least partly re-refined lubricating 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 detergency properties of a composition according to the invention are not or are not substantially altered by the envisaged addition.

[0157] A lubricating composition used according to the invention may comprise between 0.01% and 35% by mass of additives relative to the total mass of the composition, in particular between 1% and 30% by mass of additives relative to the total mass of the composition, more particularly between 5% and 25% by mass of additives, in particular as described below, relative to the total mass of the composition, in particular between 15% and 25% by mass of additives, in particular as described below, relative to the total mass of the composition.

[0158] Advantageously, a lubricating composition according to the invention may comprise at least one friction-modifying additive. The friction-modifying additives make it possible to limit friction by forming monolayers adsorbed 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.

[0159] 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 mass of the lubricating composition, of friction modifying additives.

[0160] Advantageously, a lubricating composition according to the invention comprises at least one anti-wear additive, an extreme pressure additive or their mixtures. 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. Suitable, for example, for the lubricating compositions according to the invention are anti-wear additives chosen from polysulfide additives, sulfur-containing olefin additives or even phospho-sulfur additives such as metal alkyldithiophosphates, in particular zinc alkyldithiophosphates, and more specifically zinc dialkyldithiophosphates or ZnDTP. The preferred compounds are of formula Zn((SP(S)(ORi)(OR2))2, in which Ri and R2, identical or different, independently represent an alkyl group, preferably comprising from 1 to 18 carbon atoms.

[0161] For example, 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 mass of the composition, of anti-wear additives and extreme pressure additives.

[0162] Advantageously, a lubricating composition according to the invention may also comprise, in addition, at least one antioxidant additive distinct from the spiro compound of formula (I) defined above. 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, in the presence of sludge or in an increase in the viscosity of the lubricating composition. They act in particular as radical inhibitors or hydroperoxide destroyers.

[0163] Among the commonly used antioxidant additives, mention may be made of phenolic type antioxidants, amine type antioxidant additives, phosphosulfur antioxidant additives. Some of these antioxidant additives, for example phosphosulfur antioxidant additives, may be ash-generating. The 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 by at least one CrCi2 alkyl group, N,N'-dialkyl-aryl-diamines and mixtures thereof.

[0164] Preferably, the sterically hindered phenols are chosen from compounds comprising a phenol group in which at least one vicinal carbon of the carbon carrying the alcohol function is substituted by at least one C1 to C10 alkyl group, preferably a C1 to 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 phenolic antioxidant additives. Examples of amine compounds are aromatic amines, for example aromatic amines of formula NR5R6R7 in which R5 represents an aliphatic group or an aromatic group, optionally substituted, R6 represents an aromatic group, optionally substituted, R7 represents a hydrogen atom, an alkyl group, an aryl group or a group of formula R8S(O)ZR9 in which R8 represents an alkylene group or an alkenylene group, R9 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.

[0165] Advantageously, a lubricating composition according to the invention may comprise from 0.1 to 2% by mass, relative to the total mass of the composition, of at least one antioxidant additive.

[0166] Advantageously, a lubricating composition according to the invention may also further comprise an additional detergent additive distinct from the spiro compound of formula (I) defined above. Such additional 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 additional 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 additional 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 additional 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 lubricating oil, for example a carbonate, a hydroxide, an oxalate, an acetate, a glutamate, preferably a carbonate.

[0167] 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 mass of the lubricating composition, of additional detergent additive distinct from the spiro compound of formula (I) as defined above.

[0168] Advantageously, a lubricating composition according to the invention may also comprise at least one pour point lowering additive (also called Pour point depressant (PPD) agent). By slowing the formation of paraffin crystals, pour point depressant additives generally improve the cold performance of the lubricant composition according to the invention. Examples of pour point depressants include polyalkyl methacrylates, polyacrylates, polyarylamides, polyalkylphenols, polyalkylnaphthalenes and alkylated polystyrenes.

[0169] 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 mass of the composition.

[0170] Advantageously, 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 the 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.

[0171] 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 mass of the composition.

[0172] 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 temperature. Examples of viscosity index improving polymers include polymer esters, homopolymers or copolymers, hydrogenated or non-hydrogenated, of styrene, butadiene and isoprene, homopolymers or copolymers of olefin, such as ethylene or propylene, polyacrylates and polymethacrylates (PMA).

[0173] In a particular embodiment, a lubricating composition according to the invention comprises at least one viscosity index improver chosen from olefin copolymers (Olefin Copolymers OCP), in particular ethylene-propylene copolymers OCP.

[0174] 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 mass of the lubricating composition.

[0175] A lubricating composition according to the invention may also comprise at least one anti-foam additive. The anti-foam additives may be chosen from polar polymers such as polymethylsiloxanes or polyacrylates; succinimides and their derivatives, in particular among polyisobutylene succinimide (PIBSI) or polyisobutylene succinic anhydride (PIBSA). For example, the antifoaming agent(s) may be used to counteract the effect of metallic detergents which may be present in the composition.

[0176] 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 mass of the lubricating composition.

[0177] A lubricating composition according to the invention 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 mass of the composition.

[0178] A lubricating composition according to the invention may also comprise at least one basic organic additive making it possible to increase the total base number, known as TBN, of the lubricating composition.

[0179] These basic organic additives, called “TBN boosters”, make it possible to increase the total base number of the composition; in other words, they are capable of neutralizing acids and provide improved detergent performance.

[0180] Basic organic additives improving TBN are known to those skilled in the art.

[0181] They may in particular be amino, alkylated or aromatic organic additives or even nitrogenous dispersants.

[0182] In particular, said basic organic additive(s) improving the TBN may be used in a content greater than or equal to 0.1% by mass, relative to the total mass of said lubricating composition, in particular in a content of between 0.1 and 10% by mass, more particularly between 0.5 and 7% by mass, preferably between 1 and 5% by mass.

[0183] In a particular embodiment, a lubricating composition formulated according to the invention comprises, or even consists of: - from 50% to 98.9% by mass, in particular from 65% to 85% by mass, of one or more lubricating oils at least partly re-refined; - from 0.1% to 20% by mass, preferably from 0.5% to 10% by mass, of one or more spiro compounds according to the invention as defined above, in particular of one or more spiroboronate compounds according to the invention; and - from 1% to 40% by mass, preferably from 5% to 30% by mass, more preferably from 10% to 30% by mass, for example from 15% to 25% by mass, of one or more additive(s) chosen from additional detergent additives, distinct from the or of said spiro compounds of formula (I) as defined above, in particular chosen from metallic detergent additives; anti-wear additives; antioxidants; dispersants; viscosity index improvers and mixtures thereof; the contents being expressed relative to the total mass of said lubricating composition.

[0184] In particular, a lubricating composition formulated according to the invention may comprise, or even consist of: - from 50% to 98.9% by mass, in particular from 65% to 85% by mass, of one or more lubricating oils at least partly re-refined; - from 0.1% to 20% by mass, preferably from 0.5% to 10% by mass, of one or more spiro compounds according to the invention as defined above, in particular of one or more spiroboronate compounds according to the invention; - from 0.1% to 15% by mass, in particular from 1% to 10% by mass, of one or more viscosity index improvers, in particular as defined above, notably chosen from olefin copolymers, for example ethylene-propylene OCP copolymers and their mixtures; and - optionally from 1% to 30% by mass, preferably from 3% to 20% by mass, of one or more other additives chosen from anti-wear additives, detergents, dispersants, antioxidants, and mixtures thereof, the contents being expressed relative to the total mass of said lubricating composition. Applications

[0185] As indicated previously, the compositions comprising at least one re-refined oil and a spiro compound of formula (I) as defined above, are used in various engine systems and have improved detergency properties, in particular by preventing and / or reducing deposits in various engine systems.

[0186] These may be mobile or stationary motorization systems.

[0187] 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.

[0188] A “stationary” motorization system within the meaning of the invention is a motorization system including a stationary motor. It can find applications, for example, in electrical energy production devices. This can be, for example, particular of a gas engine system, in particular a stationary gas engine.

[0189] A “mobile” motorization system is more particularly a motorization system implemented in vehicles, including light vehicles, heavy goods vehicles, so-called “off-road” mobile machines, or even marine vehicles.

[0190] A mobile motorization system can thus be a propulsion system for a vehicle, in particular a combustion engine vehicle, an electric or hybrid vehicle.

[0191] 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.

[0192] 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.

[0193] The invention will now be described by means of the following examples, given by way of illustration and not limitation of the invention. Examples

[0194] Measurement of detergency properties of lubricants - engine cleanliness test

[0195] The performance of the compositions in terms of engine cleanliness was evaluated by the TDI3 engine test according to the CEC Ll 17-20 method which measures in particular the cleanliness of the pistons. Measurement of oxidation stability

[0196] Oxidation stability is assessed by differential pressure scanning calorimetry, which determines the oxidation induction time, or OIT, for lubricating compositions. This is a standard procedure in the lubricating oil industry based on CEC L-85 T-99.

[0197] According to this protocol, the lubricating composition to be tested is heated to a high temperature (in this case, isothermal at 50°C for 5 minutes, then raised to 210°C at a rate of 40°C / min, with oxidation occurring at 210°C), and the time at which the lubricant begins to decompose is measured. The longer the test duration, expressed in minutes, the better the oxidation stability of the lubricant. Example 1 Preparation of lubricating compositions

[0198] Four lubricating compositions have been formulated: - a lubricant, not in accordance with the invention, noted CCI, based on new base oil and free from spiroboronate compound;

[0199] - a lubricant, not in accordance with the invention, noted CC2, based on new base oil and comprising a spiroboronate compound;

[0200] - a lubricant, not in accordance with the invention, noted CC3, based on a lubricating oil re-refined and free of spiroboronate compound; and

[0201] - a lubricant, in accordance with the invention, noted II, based on a lubricating oil re refined and containing a spiroboronate compound.

[0202] The components and quantities (expressed as a mass percentage) for the different lubricants are indicated in the following table. The lubricants are formulated by simple mixing at 60°C of the different components.

[0203] [Tables2] CCI CC2 CC3 II Base oil 1(1) [%] 59.6 57.6 - - Base oil 2(2) [%] 20 20 - - Re-refined lubricating oil(3) [%] - - 79.2 77.2 Additive package® [%] 13.2 13.2 13.2 13.2 OCP polymer [%] 7.2 7.2 7.6 7.6 Spiroboronate compound® [%] - 2 - 2

[0204] (1) Group III base oil (KV100 = 6.3-6.7 mm2 / s, KV40 = 37 mm2 / s, VI greater than 128-130);

[0205] (2) Group III base oil (KV100 = 4.2 mm2 / s, KV40 = 19.2 mm2 / s, VI of 124-125);

[0206] (3) Re-refined lubricating oil (KV100 = 5.3 - 5.6 mm2 / s, KV40 = 28 mm2 / s, VI of 120-121);

[0207] (4) Mixture of different additives usual in the field of lubricants and available commercially. It includes detergent, anti-wear, dispersant and antioxidant additives;

[0208] ® Spiro compound of formula (I), in which M is a boron atom, R re each have a tetradecyl group and ni and n2 are 1. Example 2

[0209] Evaluation of the detergency properties of lubricants

[0210] The detergency properties of CCI, CC2, CC3 and II lubricants were evaluated by the engine cleanliness test described above, using the TDK engine test according to CEC method L1 17-20.

[0211] The results are collected in the following table 3.

[0212] [Tables3] Lubricant CCI CC2 CC3 II TDI CEC L-117-20 52 58 42 60 Relative variation associated with the introduction of the spiro compound,J +11.5% +43%

[0213] Relative variation in engine cleanliness results according to the TDK test linked to the addition of the spiro compound.

[0214] These results show that the implementation of a spiroboronate compound in combination with a re-refined lubricating oil improves the detergency properties, in particular engine cleanliness. Surprisingly, the improvement in the detergency properties associated with the additivation by a spiro additive according to the invention at the level of a lubricant based on at least partly re-refined lubricating oil (+43% improvement in the detergent effect measured according to the CEC L-85 T-99 standard, associated with the implementation of the spiro additive at the level of the lubricant based on re-refined oil) is much higher than the effect observed during the additivation by the spiro additive of a lubricant based on virgin oil (+11.5% improvement in the detergent effect measured according to the CEC L-85 T-99 standard), thus demonstrating a potentiating effect of the detergency efficiency associated with the spiro compound in combination with a re-refined lubricating oil. Example 3

[0215] Evaluation of oxidation stability properties

[0216] The oxidation stability properties of CCI, CC2, CC3 and II lubricants were evaluated according to the protocol based on CEC L-85 T-99 standard, described above.

[0217] The oxidation induction time (OIT) results are collected in the following Table 4.

[0218] [Tables4] Lubricant CCI CC2 CC3 II Oxidation induction time (in min) 73 213 88 >250

[0219] These results show that the combination of a spiroboronate compound and a re-refined lubricating oil in a lubricating composition additionally improves the oxidation stability of the lubricant.

Claims

Claims

1. Lubricating composition, comprising at least: i. an at least partly re-refined lubricating oil; and ii. a spiro compound of the following formula (I) 0 ,9 y---o o---% \ / + \___ / . \\ MH / / a in which: M is an atom chosen from boron and aluminum; ni and n2 are, independently of each other, 0, 1, 2, 3 or 4, and R represent, independently of each other, a hydrocarbon group comprising from 1 to 50 carbon atoms.

2. Lubricating composition according to claim 1, characterized in that it further comprises one or more base oils distinct from said at least partly re-refined lubricating oil(s), in particular one or more new base oils.

3. Lubricating composition according to any one of the preceding claims, characterized in that the at least partly re-refined lubricating oil(s) represent more than 10% by mass, in particular more than 20% by mass, more particularly more than 30% by mass, in particular more than 40% by mass, of the total mass of the lubricating composition.

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

5. Lubricating composition according to any one of the preceding claims, characterized in that the at least partly re-refined lubricating oil has: a kinematic viscosity measured at 100°C according to standard ASTM D445 greater than or equal to 3.0 mmVs, in particular greater than or equal to 4.0 mm2 / s, in particular between 4.0 and 12 mm2 / s, in particular greater than or equal to 4.3 mm2 / s and more particularly between 4.4 and 10 mm2 / s, in particular between 4.5 and 6 mm2 / s; and / or a viscosity index, determined according to standard ASTM D2270, greater than or equal to 110, in particular between 110 and 130, preferably between 112 and 125, and more particularly between 118 and 124.

6. Lubricating composition according to any one of the preceding claims, characterized in that said spiro compound is of formula (I) in which M is a boron atom.

7. Lubricating composition according to any one of the preceding claims, characterized in that said spiro compound is of formula (I) in which the substituents R represent, independently of one another, a linear or branched aliphatic chain, in particular an alkyl chain, preferably linear, of C1 to C50, in particular of C3 to C30, in particular of C5 to C25, more particularly of C8 to C15, more preferably of Cu; preferably n1 and n2 are 1 and the substituents R are identical.

8. Lubricating composition according to any one of the preceding claims, characterized in that the said spiro compound(s) are used in a content of between 0.05% and 15% by mass relative to the total mass of the lubricating composition, in particular of between 0.1% and 10% by mass, more particularly of between 1% and 5% by mass relative to the total mass of the lubricating composition.

9. Lubricating composition according to any one of the preceding claims, characterized in that it further comprises one or more additives, distinct from said spiro compound(s), in particular chosen from friction modifying additives, anti-wear additives, extreme pressure additives, additional detergents, basic organic additives improving the total base number, antioxidants, viscosity index improvers, pour point lowering additives, dispersants, anti-foaming agents, thickeners, corrosion inhibitors, copper passivating agents, and mixtures thereof.

10. Use of a lubricating composition as defined according to one of claims 1 to 9, for preventing and / or reducing deposits in a motorization system lubricated by means of said lubricating composition- burning, especially in an internal combustion engine.