Use of an antioxidant to reduce and / or prevent the toxicity of a lubricating composition

Abstract

The present invention relates to the use of at least one antioxidant in a lubricant composition, said at least one antioxidant comprising at least one oligomer and / or polymer comprising at least one d

Description

Description Title of the invention: Use of an antioxidant to reduce and / or prevent the toxicity of a lubricating composition TECHNICAL FIELD

[0001] The present invention relates to the field of antioxidant additives used in lubricating compositions. The present invention relates in particular to the use of specific polymeric antioxidants in a lubricating composition in order to reduce and / or prevent its toxicity. TECHNOLOGICAL BACKGROUND

[0002] As is known, lubricating compositions are mainly used to reduce friction between two moving elements (industrial machinery, motor vehicles, etc.). The introduction of a lubricating composition between two parts therefore makes it possible to reduce friction and therefore the negative effects resulting from it, such as wear, fatigue; corrosion of parts, breakage, etc. For this purpose, a lubricating composition is a balanced mixture of a certain number of components generally consisting of a base oil (mineral or synthetic oil) and base additives, such as anti-wear additives, antioxidant additives, etc.

[0003] They are thus used in many fields, such as in the automotive industry (to lubricate, for example, thermal engines or transmission boxes), in wind power (for gears), in energy production (gas turbines or any other turbines dedicated to energy production). Also, in the maritime, agricultural or public works sectors, a significant quantity of lubricating compositions are used as engine oil, stern oil, hydraulic fluids.

[0004] However, some of the lubricating compositions used in the above-mentioned areas, such as wind farms, the marine environment, etc., are likely to be dispersed in the environment and are a source of pollution of the seas / oceans, their soils, runoff water or even groundwater.

[0005] Thus, a lubricating composition must, on the one hand, meet specific technical performance requirements to reduce friction between two moving elements, and, on the other hand, take into account new requirements relating to the protection of humans and their environment.

[0006] In particular, antioxidant additives are also used in a large number of everyday applications and objects, and, despite their relatively modest content in the lubricating compositions in which they are incorporated, their contribution is crucial with regard to the lifespan and the conservation of the physicochemical properties of the latter.

[0007] To date, two main categories of antioxidants are used: aromatic amines, such as diphenylamine monomers (DPA) and phenolic compounds. Unfortunately, recent studies show that the toxicological profile of standard antioxidants, such as those based on aromatic amines, is evolving negatively, in a drastic and worrying way in view of the established dangers related to humans and their environment (carcinogenic, mutagenic, or toxic for reproduction, known as "CMR" character, aquatic toxicity / ecotoxicity, bioaccumulation, substance classified as Persistent, Bioaccumulative and Toxic, known as "PBT"). This trend is accelerating under the influence of international regulatory agencies pushing for increasingly precise and intensive characterization of chemical materials produced in very large volumes. For example, the European Chemicals Agency (ECHA) reports the obvious dangers of the main antioxidants belonging in particular to the family of diphenylamine monomers (DPA) used massively in the chemical fluids and lubricants industry.

[0008] In particular, standard antioxidants and their proven toxicity(ies) are listed in Table 1 below: Table 1]

[0009] The toxicity potential of certain oxidants has been confirmed in particular by recent scientific research, such as that of Tian et al. Science, 2021, 371 (6525), 185-189 or that of W. Huang et al. Environ.Sci.Technol.Lett. 2021, 8, 381-385, which shows that the main antioxidants used to date are toxic to humans and / or the environment.

[0010] The publication by Tian et al. focuses on the effect of antioxidants on Pacific coho salmon (Oncorhynchus kisutch) (Northwestern USA). The authors found that in this salmon, exposure to stormwater results in acute mortality when adult salmon migrate to urban streams to spawn under the influence of oxidation products of antioxidants present in tire wear particles.

[0011] It is known from the prior art that oligomers and / or polymers comprising repeating units of diphenylamine monomers exhibit good antioxidant properties for lubricating oils containing synthetic ester-based lubricants (US 5,489,711, US 2019 / 127526, US 6,426,324, EP 2,217,687 and US 3,509,214).

[0012] However, document WO 2019 / 126751, published in 2016, teaches that diphenylamine derivatives, including oligomers with diphenylamine repeating units, are toxic (see start page 3).

[0013] There is therefore a very urgent need in the state of the art to develop alternative antioxidant additives to standard antioxidants such as those mentioned above in order to manufacture lubricant compositions that are more respectful of humans and their environment, especially in the current context in which current substances are evolving towards CMR classifications according to European regulations (REACH). Recent examples concern antioxidants well known to lubricant formulators such as Irganox L57 and Ethanox 4702 (also called 4,4'-Methylene-bis-(2,6-di-tert-butylphenol) (MEDBP) (see table 4, entry 3), both CMR. Other evaluations are underway under the aegis of ECHA and ANSES, such as that of Irganox L67, which in the long term risks evolving and experiencing the same evolution and classification as its counterpart Irganox L57.The skilled person is therefore deprived of satisfactory and safe formulation solutions, i.e. non-toxic, for applications which may be general public (for example, car engine oils) and environmentally sensitive (lost lubrication, leaks into the environment, water and oceans, etc., manual maintenance of machines and equipment, release of vapors or aerosols under the effect of the heat produced within the system, etc.).

[0014] There is therefore an urgent and crucial need in the state of the art to develop alternative antioxidant additives for lubricating compositions having both a satisfactory antioxidant effect, while making it possible to increase the level of safety (reduction in danger for humans) and to reduce the environmental impact of the lubricating composition in which the antioxidant is incorporated, in the targeted fields of application (automobile, industry, wind power, ships, energy production, agricultural and forestry environments, 2T engine tools, etc.), STATEMENT OF THE INVENTION

[0015] In this context, the Applicant has endeavored to develop compounds exhibiting both antioxidant properties, while making it possible to prevent and / or reduce the toxicity of a lubricant composition in which they are incorporated, with respect to that of standard antioxidants, such as those mentioned above, belonging in particular to the family of diphenylamine (DPA) or phenolic monomers.

[0016] As will be illustrated in the experimental part below, it has notably demonstrated, surprisingly and unexpectedly, that once oligomerized and / or polymerized, the toxicity of diphenylamine monomers is drastically reduced. They thus make it possible to form oligomers and / or polymers comprising at least one diphenylamine repeating unit having both antioxidant properties, suitable for the various fields of use of lubricating compositions (vehicle engine, wind turbine gears, etc.), while being weakly or not at all toxic to humans and / or the environment. The present invention thus goes against the teaching of the document WO 2019 / 126751 mentioned above which teaches that diphenylamine derivatives including oligomers having the diphenylamine repeating units are toxic.

[0017] However, the experimental tests below show that the antioxidants according to the invention, which were selected by the Applicant, are not arbitrary and have a different technical effect (namely they make it possible to reduce / prevent / prevent the toxicity of a lubricating composition) compared to other antioxidant compounds, in particular compared to diphenylamine (DPA) monomers.

[0018] As mentioned above, the antioxidant properties of some of the compounds according to the invention have for example been demonstrated in the prior art, in particular in documents FR 2 924 122, EP 0734 432 and WO 2009 / 071857. Although the use of the compounds according to the invention has already been envisaged in the prior art as antioxidant additives, to the knowledge of the Applicant, no study has demonstrated their non-toxicity and consequently their interest in preventing and / or reducing, or even preventing, the toxicity of a lubricating composition. The Applicant has indeed demonstrated the absence or low toxicity of the antioxidant compounds according to the invention, whether in terms of neurotoxicity, reprotoxicity, mutagenicity or even carcinogenicity, which reinforces their interest as an alternative to DPA or phenolic monomers as an antioxidant agent in lubricating compositions.

[0019] Furthermore, the Applicant considers that testing the toxicity of antioxidants is not an obvious measure for those skilled in the art. This is why it has developed an effective and in-depth methodology based on four models (C: carcinogenic, M: mutagenic, R: reprotoxic and N: neurotoxic) coupled with an in vivo biological measurement in order to indisputably test the toxicity of a compound in a global manner. This methodology has notably made it possible to highlight the greatly reduced toxicity of the diphenylamine oligomers / polymers according to the invention compared to other usual antioxidant compounds. This invention constitutes a unique solution to date allowing lubricant formulators to offer high-performance or even very high-performance and sustainable products, i.e. without the risk of seeing their classifications evolve towards CMR categories or otherwise toxic and / or neurotoxic. SUMMARY OF THE INVENTION

[0020] Thus, the present invention relates to the use of at least one antioxidant in a lubricating composition, said at least one antioxidant comprising at least one oligomer and / or polymer comprising at least one diphenylamine repeating unit of general formula (I): wherein each of R1 to R10 is independently selected from a hydrogen atom, an alkyl group which is a saturated, straight or branched hydrocarbon group comprising from 1 to 24 carbon atoms and an aralkyl group which is an alkyl group as described above in which at least one of the carbon atoms is substituted by a monocyclic or polycyclic aromatic hydrocarbon aryl group comprising 5 to 14 carbon atoms, to reduce and / or prevent the toxicity of said lubricating composition.

[0021] Of course, the various features, variants and embodiments of the invention may be combined with each other in various combinations to the extent that they are not incompatible or mutually exclusive.

[0022] In the present invention, unless otherwise specified, the term "comprising" and its derivatives should be understood as non-limiting and not excluding the presence of other components or steps. In certain particular embodiments, the term "comprising" may be understood as "consisting essentially of" or "consisting of".

[0023] Unless otherwise specified, the intervals mentioned in the present invention are understood to be inclusive. DETAILED DESCRIPTION

[0024] The present invention thus relates to the use of at least one antioxidant in a lubricating composition, said at least one antioxidant comprising at least one oligomer and / or polymer comprising at least one diphenylamine repeating unit of general formula (I): wherein each of R1 to R10 is independently selected from: a hydrogen atom, an alkyl group which is a saturated, linear or branched hydrocarbon group comprising from 1 to 24 carbon atoms and an aralkyl group which is an alkyl group as described above in which at least one of the carbon atoms is substituted by a monocyclic or polycyclic aromatic hydrocarbon aryl group comprising 5 to 14 carbon atoms, to reduce and / or prevent the toxicity of said lubricating composition.

[0025] Antioxidants are specialty chemical additives that serve to interrupt the degradation process linked to oxidation in compositions in which they are incorporated, in this case lubricating compositions.

[0026] According to the invention, by "toxicity" of a substance and / or a composition, it is meant that said substance and / or said composition has at least one, preferably at least two, in particular at least three, typically at least four, such as at least four, five, six, or even all of the following toxicities: - reprotoxicity which corresponds to the alteration of fertility or alteration of the unborn mammal / living being, - mutagenicity which is the propensity of a substance to cause genetic mutations, - acute toxicity which is the toxicity induced, in a short period of time (e.g. 24 hours), by the administration or contact (topical application) of a single dose (possibly massive) or of several doses acquired in this period of time of a toxic product or mixture (natural or chemical), - ecotoxicity which is the set of imbalances or nuisances caused by an industrial activity or the placement of a body, a foreign product in a natural environment generally linked to human activity; - neurotoxicity which is the ability of a substance or compound to induce harmful effects in the nervous system of a mammal / living being, such as humans or planarians, - the carcinogenic character which is the propensity of a substance to cause / provoke the appearance of cancer or participate in its aggravation, its appearance, - toxicity on the synthesis, degradation, transport and mode of action of hormones, as is the case with endocrine disruptors (indirect toxicity via the physiological modifications they cause).

[0027] A compound with a CMR character (carcinogenic, mutagenic, or toxic for reproduction) thus presents various toxicities.

[0028] According to a characteristic of the invention, the toxicity thus comprises one or more of the following toxicities: neurotoxicity, reprotoxicity, mutagenicity, acute toxicity, carcinogenicity, toxicity on the synthesis, degradation, transport and mode of action of hormones and ecotoxicity.

[0029] "By reducing" the toxicity of a lubricating composition, it is meant that said at least one antioxidant according to the invention (namely comprising at least one oligomer and / or polymer comprising at least one diphenylamine repeating unit of general formula (I)) is capable and / or configured to reduce the toxicity of a lubricating composition in which it is included, namely by its presence, in particular compared to other possible standard antioxidant compounds which are generally toxic, said at least one oxidant according to the invention comprising at least one oligomer and / or polymer comprising at least one diphenylamine repeating unit of general formula (I) makes it possible to lower / reduce the toxicity of a lubricating composition.

[0030] “By preventing” the toxicity of a lubricating composition, it is meant that said at least one oxidant according to the invention comprising at least one oligomer and / or polymer comprising at least one diphenylamine repeating unit of general formula (I) makes it possible to prevent the lubricating composition from being considered toxic and / or to prevent the appearance of toxic symptoms in a mammal or any other living being, such as a human being or an animal which would be in contact with said lubricating composition.For example, neurotoxic symptoms may affect the central nervous system (CNS) and present the following effects: headaches, loss of appetite, drowsiness, mood and personality disorders, cognitive impairment (learning and concentration difficulties), or affect the peripheral nervous system (PNS) and present the following effects: motor impairment such as weakness, tremors, incoordination, convulsions, etc. or sensory impairment, such as reduced hearing, color vision, tinnitus, loss of balance, etc.; these effects may or may not be reversible depending on the degree of acute or chronic exposure of the mammal. For example, symptoms of acute toxicity may be skin irritations, an allergic skin reaction, vomiting, etc.

[0031] In general, said at least one antioxidant according to the invention (namely comprising at least one oligomer and / or polymer comprising at least one diphenylamine repeating unit of general formula (I)) is capable of and / or configured to reduce and / or prevent the toxicity of a lubricating composition at the different stages of its life, namely its implementation, its use and its end of life.

[0032] According to a particular embodiment, said oligomer and / or polymer comprising at least one diphenylamine repeating unit of general formula (I) may also comprise at least one phenyl a-naphthylamine repeating unit of general formula (II): wherein each of R11 to R22 is independently selected from: a hydrogen atom and an alkyl group which is a saturated, linear or branched hydrocarbon group comprising from 1 to 24 carbon atoms.

[0033] By "polymer" of at least one diphenylamine and optionally at least one phenyl a-naphthylamine, is meant in the present invention a compound comprising the repetition of at least two diphenylamine units with optionally at least one phenyl a-naphthylamine unit.

[0034] By "oligomer" of at least one diphenylamine and optionally at least one phenyl a-naphthylamine, is meant in the present invention a polymer of at least one diphenylamine and optionally at least one phenyl a-naphthylamine which comprises between 2 and 15 repeating units, or a mixture of such compounds. It may in particular be a dimer, a trimer, a tetramer, a pentamer, a hexamer, a heptamer, an octamer, a nonamer, a decamer and / or any mixture of such compounds. Preferably, the oligomer contains (in relative %) at least 70%, preferably 80% and in particular 90% by mass of dimer, trimer, tetramer, pentamer or a mixture of such compounds.

[0035] By "repeating unit" diphenylamine or phenyl a-naphthylamine, we mean the fact that, in the final structure of the oligomer or polymer obtained according to the invention, there is present at least one diphenylamine unit and at least one phenyl a-naphthylamine unit, or at least two diphenylamine units with optionally at least one phenyl a-naphthylamine unit.

[0036] The diphenylamine and phenyl a-naphthylamine repeating units can be positioned in any way relative to each other in the structure of the polymer or oligomer according to the invention. Thus, the polymer or oligomer can comprise, at least on a part of its structure, a regular alternation of diphenylamine and phenyl a-naphthylamine repeating units. It can comprise, at least on a part of its structure, a random distribution of the diphenylamine and phenyl a-naphthylamine repeating units. Finally, it can comprise, on at least a part of its structure, a block comprising a single type of diphenylamine or phenyl a-naphthylamine repeating unit.

[0037] In one embodiment, the polymer and / or oligomer according to the invention comprises in its structure only diphenylamine and phenyl a-naphthylamine repeating units. In another embodiment, the polymer and / or oligomer according to the invention comprises in its structure only diphenylamine repeating units.

[0038] By "diphenylamine" is meant a compound of formula (I): wherein each of R1 to R10 is independently selected from: a hydrogen atom, an alkyl group (which is a saturated, straight or branched hydrocarbon group comprising from 1 to 24 carbon atoms) and an aralkyl group (which is an alkyl group as described above in which at least one of the carbon atoms is substituted by a monocyclic or polycyclic aromatic hydrocarbon aryl group comprising from 5 to 14 carbon atoms).

[0039] In one embodiment, the at least one diphenylamine of formula (I) is an alkylated diphenylamine, i.e., at least one of R1 to R10 is an alkyl or aralkyl group. In another embodiment, at least one of R1 to R5 is an alkyl or aralkyl group, and at least one of R6 to R10 is an alkyl or aralkyl group.

[0040] In general, each of R1 to R10 is independently selected from: a hydrogen atom or an alkyl group which is a saturated, linear or branched hydrocarbon group comprising from 1 to 24 carbon atoms, preferably comprising from 1 to 15 carbon atoms, in particular from 3 to 12 carbon atoms and typically from 3 to 10 carbon atoms.

[0041] Generally, at least one, particularly at least two and typically at least three substituents among R1 to R10 is an alkyl group (as defined below), the other substituents being a hydrogen atom. Generally less than nine, particularly less than six and typically less than four of the substituents among R1 to R10 is an alkyl group, the other substituents being a hydrogen atom. According to the invention, “at least one” includes the following numbers and all intervals between these values: 1; 2; 3; 4; 5; 6; 7; 8; 9; 10. Also, within the scope of the invention, “less than nine” includes the following numbers and all intervals between these values: 9; 8; 7; 6; 5; 4; 3; 2; 1. For example, one or two substituents of R1 to R10 is an alkyl group, the other substituents being a hydrogen atom.

[0042] In the present invention, the term "alkyl" means a saturated, linear, branched or cyclic hydrocarbon group comprising from 1 to 24 carbon atoms. Preferably, an alkyl group comprises from 1 to 12 carbon atoms. Thus, according to the invention, "an alkyl comprising 1 to 24 carbon atoms" includes the following carbon numbers and all the intervals between these values: 1; 2; 3; 4; 5; 6; 7; 8; 9; 10; 11; 12; 13; 14; 15; 16; 17; 18; 19; 20; 21; 22; 23; 24. Among the alkyl groups, mention may be made in particular of the methyl group, the ethyl group, the n-propyl group, the iso-propyl group, the n-butyl group, the tert-butyl group, the iso-butyl group, the n-pentyl group, the iso-pentyl group, the n-hexyl group, the group cyclohexyl, n-heptyl group, n-octyl group, tert-octyl group, iso-octyl group, n-nonyl group, n-decyl group, n-undecyl group, n-dodecyl group and iso-dodecyl group. In a particular embodiment, an alkyl group is selected from the group consisting of the tert-butyl group and the tert-octyl group, or the n-nonyl group (nC9), and may be selected for example from the group consisting of the tert-butyl group and the tert-octyl group.

[0043] In the present invention, the term "aralkyl" means an alkyl group in which at least one of the carbon atoms is substituted by an aryl group. Examples of aralkyl groups include, in particular, the 1-methyl-1-phenylethyl group, a styryl group (C6H5-CH=CH-) or methylstyryl.

[0044] In the present invention, the term "aryl group" means a monocyclic or polycyclic aromatic hydrocarbon group. Each aromatic or polyaromatic ring comprises 5 to 14 atoms. Examples of aryl groups include, in particular, the phenyl group.

[0045] In one embodiment, the diphenylamine of formula (I) is selected from the group consisting of N,N-diphenylamine, N,N-di-(p-tert-butylphenyl)amine, N,N-di-(p-tert-octylphenyl)amine, N-(p-tert-butylphenyl)-N-phenylamine, N-(p-tert-octylphenyl)-N-phenylamine, N-(p-tert-butylphenyl)-N-(p-tert-octylphenyl)amine, tert-butylated and / or tert-octylated diphenylamines, nonylated diphenylamines, and any mixture thereof.

[0046] In a particular embodiment, the polymer or oligomer according to the present invention comprises only diphenylamine units. The oligomer comprising at least one diphenylamine repeating unit of general formula (I) according to the invention may thus be a dimer, a trimer, a tetramer, a pentamer of one or more of these diphenylamines of formula (I) described above, and is generally a dimer or a trimer. The oligomer may correspond, for example, to a dimer or a trimer of di-(p-tert-octylphenyl)amine (DODPA), alone or as a mixture.

[0047] In particular, when the oligomer comprising at least one diphenylamine repeating unit of general formula (I) according to the invention is a dimer, the latter has at least three, generally at least four substituents among all the substituents R1 to R10 of the repeating unit of formula (I) forming the dimer which are not a hydrogen atom (the other substituents are thus hydrogen atoms). According to the invention, "at least three substituents among all the substituents R1 to R10 of the repeating unit of formula (I) forming the dimer" comprises the following values: 3; 4; 5; 6; 7; 8; 9; 10; 11; 12; 13; 14; 15; 16; 17; 18; 19; 20 and may correspond for example to three or four substituents among all the substituents R1 to R10 forming the dimer. In general, said at least three substituents are preferably each an alkyl group, ie: saturated, linear or branched hydrocarbon group comprising from 1 to 24 carbon atoms, preferably comprising from 3 to 15 carbon atoms, in particular from 5 to 12 carbon atoms and typically from 6 to 9 carbon atoms. By way of example, said at least three substituents may be, independently of one another, a tert-butyl group or a tert-octyl group or even an n-nonyl group. Generally, said at least three substituents are independently distributed over the two diphenylamine repeating units of formula (I) of the dimer. Typically, each repeating unit comprises at least one of said three substituents. For example, one repeating unit of the dimer comprises at least one substituent from R1 to R10 which is not a hydrogen atom (and is preferably an alkyl group as defined above) and the other unit of the dimer comprises at least two substituents from R1 to R10 which is not a hydrogen atom (and is preferably an alkyl group as defined above).

[0048] In general, when the oligomer comprising at least one diphenylamine repeating unit of general formula (I) according to the invention is a trimer, the latter has at least one, preferably at least two substituents among all the substituents R1 to R10 of the repeating unit of formula (I) forming the trimer, which is not a hydrogen atom (the other substituents are thus hydrogen atoms). According to the invention, "at least one substituent among all the substituents R1 to R10 of the repeating unit of formula (I) forming the trimer" comprises the following values: 1, 2, 3; 4; 5; 6; 7; 8; 9; 10; 11; 12; 13; 14; 15; 16; 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30 and may correspond for example to five or six substituents among all the substituents R1 to R10 forming the trimer. In particular, said at least one, preferably five, or even six substituents are generally each an alkyl group, ie: saturated, linear or branched hydrocarbon group comprising from 1 to 24 carbon atoms, preferably comprising from 3 to 15 carbon atoms, in particular from 5 to 12 carbon atoms and typically from 6 to 9 carbon atoms. By way of example, said substituent(s) may be independently of one another a tert-butyl group or a tert-octyl group or an n-nonyl group and is typically a tert-octyl group. Generally, said at least one, preferably five, or even six substituents is / are independently distributed over the three diphenylamine repeating units of formula (I) forming the trimer. Typically, each repeating unit of the trimer comprises at least one, or even two substituents from R1 to R10 which is an alkyl group as defined above (the other substituents being hydrogen atoms).Generally, said alkyl substituent(s) are independently distributed over the three diphenylamine repeating units of formula (I) of the trimer. Typically, each repeating unit of the trimer comprises at least one, or even two alkyl substituents (the other substituents being hydrogen atoms).

[0049] The diphenylamines according to the invention may be present alone or as a mixture with each other. For example, they may be present in the form of a mixture of N,N-diphenylamine, N,N-di-(p-tert-butylphenyl)amine, N,N-di-(p-tert-octylphenyl)amine, N-(p-tert-butylphenyl)-N-phenylamine, N-(p-tert-octylphenyl)-N-phenylamine and N-(p-tert-butylphenyl)-N-(p-tert-octylphenyl)amine, tert-butylated and / or tert-octylated diphenylamines, nonylated diphenylamines.

[0050] The oligomers and / or polymers comprising at least one diphenylamine repeating unit of general formula (I) may correspond to the compounds exemplified below.

[0051] According to the present invention, phenyl a-naphthylamine denotes a compound of formula (II): wherein each of R11 to R22 is independently selected from: a hydrogen atom and an alkyl group which is a saturated, linear or branched hydrocarbon group comprising from 1 to 24 carbon atoms.

[0052] In one embodiment, at least one of R11 to R22 is an alkyl group. In one embodiment, only one of R11 to R22 is an alkyl group, in particular a tert-octyl group.

[0053] In a particular embodiment, the phenyl a-naphthylamine is N-(4-tert-octylphenyl)-1-naphthylamine, CAS number 4572-51-4 (OPAN).

[0054] In one embodiment of the invention, the at least one diphenylamine is in the form of a mixture of N,N-diphenylamine, N,N-di-(p-tert-butylphenyl)amine, N,N-di-(p-tert-octylphenyl)amine, N-(p-tert-butylphenyl)-N-phenylamine, N-(p-tert-octylphenyl)-N-phenylamine and N-(p-tert-butylphenyl)-N-(p-tert-octylphenyl)amine, and the at least one phenyl a-naphthylamine is N-(4-tert-octylphenyl)-1-naphthylamine (OPAN).

[0055] In another embodiment of the invention, the at least one diphenylamine is di-(p-tert-octylphenyl)amine (DODPA) and the at least one phenyl a-naphthylamine is N-phenyl 1,1,3,3-tetramethylbutylnaphthalen 1-amine (OPAN). The oligomer forming the antioxidant according to the invention can thus correspond to a trimer 2DODPA / 1OPAN, 1 DODPA / 2OPAN, 3DODPA. According to one embodiment, said at least one oligomer can correspond to a mixture of trimers, such as a mixture of 2DODPA / 1OPAN, 1 DODPA / 2OPAN and 3DODPA. In particular, within this mixture, the oligomer 2DODPA / 1OPAN is the majority. In general, said at least one oligomer comprises a mixture of trimers (such as 2DODPA / 1OPAN, 1 DODPA / 2OPAN, 3DODPA), tetramers, pentamers and hexamers.

[0056] The relative proportions by mass of the two types of diphenylamine and phenyl a-naphthylamine units within the polymer or oligomer can vary widely from 0 / 100 to 100 / 0. Preferably, the relative proportion by mass of diphenylamine / phenyl a-naphthylamine is between 100 / 0 and 10 / 90, in particular between 100 / 0 and 30 / 70 (such as 50 / 50 or 80 / 20), in particular between 100 / 0 and 90 / 10 and typically between 100 / 0 and 95 / 5.

[0057] The polymer or oligomer according to the present invention forming said at least one antioxidant according to the invention can in particular be prepared according to the process described in the application of patent FR 2010199 filed by the Applicant company, namely in a continuous reactor. A person skilled in the art is able to adjust the quantities of diphenylamine and phenyl a-naphthylamine to be introduced into the reactor depending in particular on the desired structure of the oligomer or polymer to be synthesized and the desired thermal characteristics. The polymer or oligomer according to the present invention forming said at least one antioxidant according to the invention can in particular also be prepared according to the process described in document WO 2008 / 022028.

[0058] For the present invention, the Applicant has demonstrated the non-toxicity of said at least one antioxidant comprising at least one oligomer and / or one polymer comprising at least one diphenylamine repeating unit of formula (I) and optionally at least one phenyl a-naphthylamine repeating unit of formula (II) according to the invention by QSAR modeling tests for neurotoxicity, for reprotoxicity, for mutagenicity and carcinogenicity.

[0059] In particular, the oligomer and / or polymer comprising at least one diphenylamine repeating unit of formula (I) and optionally at least one phenyl a-naphthylamine repeating unit of formula (II) has a QSAR value for the measurement of each of the following toxicities: neurotoxicity (neurotoxic QSAR), reprotoxicity (reprotoxic QSAR), mutagenicity (mutagenic QSAR) and carcinogenicity (carcinogenic QSAR), corresponding to a statistical threshold value (%) subtracted from a delta of at least 30%, said statistical threshold value being determined, for each of said toxicities, by QSAR (quantitative structure-activity relationship) modeling according to the method described below in the experimental part,

[0060] According to the invention, "a delta of at least 30%" for QSAR modeling includes the following values ​​and all intervals between these values: 30; 31; 32; 33; 34; 35; 36; 37; 38; 39; 40; 41; 42; 43; 44; 45; 46; 47; 48; 49; 50; 51; 52; 55; 60; 65; 70; 75; 80; 85; 90; 91; 92; 93; 94; 95; 96; 97; 98; 99; 100 (this range of at least 30% is to be adapted for each of the toxicities).

[0061] According to one embodiment, the statistical threshold value (neurotoxic QSAR) in percentage is typically 55%.

[0062] Preferably, the delta for the neurotoxic QSAR measurement is at least 45%, advantageously at least 55% and typically at least 53%.

[0063] In general, the oligomer and / or the polymer comprising at least one diphenylamine repeating unit of formula (I) and optionally at least one phenyl a-naphthylamine repeating unit of formula (II) has a percentage value (%) by QSAR modeling of less than or equal to 10%, preferably less than or equal to 5% and typically less than or equal to 2% for the measurement of neurotoxicity (neurotoxic QSAR).

[0064] According to the invention, a value less than or equal to 10% for neurotoxic QSAR modeling includes the following values ​​and all intervals between these values: 10; 9; 8; 7; 6; 5; 4; 3; 2; 1; 0.9; 0.8; 0.70; 0.69; 0.68; 0.67; 0.66; 0.65; 0.64; 0.63; 0.62; 0.61; 0.60; 0.59; 0.58; 0.57; 0.56; 0.55; 0.54; 0.53; 0.52; 0.51; 0.50; 0.49; 0.48; 0.47; 0.46; 0.45; 0.44; 0.42; 0.40; 0.38; 0.36; 0.34; 0.32; 0.30; 0.28; 0.26; 0.24; 0.22; 0.20; 0.18; 0.16; 0.14; 0.12; 0.10; 0.09; 0.08; 0.07; 0.06; 0.005; 0.04; 0.03; 0.02; 0.01; 0.00.

[0065] According to another embodiment, the statistical threshold value (reprotoxic QSAR) in percentage is typically 90%.

[0066] Preferably, the delta for the measurement of the reprotoxic QSAR is at least 41%, advantageously at least 43% and typically at least 46%.

[0067] In general, the oligomer and / or polymer comprising at least one diphenylamine repeating unit of formula (I) and optionally at least one phenyl a-naphthylamine repeating unit of formula (II) has a percentage value (%) by QSAR modeling of less than or equal to 65%, preferably less than or equal to 50% and typically less than or equal to 45% for the measurement of reprotoxicity (reprotoxic QSAR).

[0068] According to the invention, a value less than or equal to 65% for reprotoxic QSAR modeling includes the following values ​​and all intervals between these values: 65; 64; 63; 62; 61; 60; 59; 58; 57; 56; 55; 54; 53; 52; 51; 50; 49; 48; 47; 46; 45; 44; 43; 42; 41; 40; 39; 38; 37; 36; 35; 34; 33; 32; 31; 30; 29; 28; 27; 26; 25; 24; 23; 22; 21; 20; 15; 10; 5; 3; 1; 0.50; ; 0.49; 0.48; 0.47; 0.46; 0.45; 0.44; 0.42; 0.40; 0.38; 0.36; 0.34; 0.32; 0.30; 0.28; 0.26; 0.24; 0.22; 0.20; 0.18; 0.16; 0.14; 0.12; 0.10; 0.09; 0.08; 0.07; 0.06; 0.005; 0.04; 0.03; 0.02; 0.01; 0.00.

[0069] According to another embodiment, the statistical threshold value (mutagenic QSAR) in percentage is typically 58%.

[0070] Preferably, the delta for the measurement of the mutagenic QSAR is at least 48%, advantageously at least 53% and typically at least 56%.

[0071] Generally, the oligomer and / or polymer comprising at least one diphenylamine repeating unit of formula (I) and optionally at least one phenyl a-naphthylamine repeating unit of formula (II) has a percentage value (%) by QSAR modeling of less than or equal to 10%, preferably less than or equal to 5% and typically less than or equal to 2% for the measurement of mutagenicity (mutagenic QSAR).

[0072] According to the invention, a value less than or equal to 10% for mutagenic QSAR modeling includes the following values ​​and all intervals between these values: 10; 9; 8; 7; 6; 5; 4; 3; 2; 1; 0.9; 0.8; 0.70; 0.69; 0.68; 0.67; 0.66; 0.65; 0.64; 0.63; 0.62; 0.61; 0.60; 0.59; 0.58; 0.57; 0.56; 0.55; 0.54; 0.53; 0.52; 0.51; 0.50; 0.49; 0.48; 0.47; 0.46; 0.45; 0.44; 0.42; 0.40; 0.38; 0.36; 0.34; 0.32; 0.30; 0.28; 0.26; 0.24; 0.22; 0.20; 0.18; 0.16; 0.14; 0.12; 0.10; 0.09; 0.08; 0.07; 0.06; 0.005; 0.04; 0.03; 0.02; 0.01; 0.00.

[0073] According to another embodiment, the statistical threshold value (carcinogenic QSAR) in percentage is typically 85%.

[0074] Preferably, the delta for the measurement of the carcinogenic QSAR is at least 77%, advantageously at least 82% and typically at least 85%.

[0075] In general, the oligomer and / or polymer comprising at least one diphenylamine repeating unit of formula (I) and optionally at least one phenyl a-naphthylamine repeating unit of formula (II) has a percentage (%) value by QSAR modeling less than or equal to 10%, preferably less than or equal to 5% and typically less than or equal to 2% for the measurement of carcinogenicity (carcinogenic QSAR).

[0076] According to the invention, a value less than or equal to 10% for carcinogenic QSAR modeling includes the following values ​​and all intervals between these values: 10; 9; 8; 7; 6; 5; 4; 3; 2; 1; 0.9; 0.8; 0.70; 0.69; 0.68; 0.67; 0.66; 0.65; 0.64; 0.63; 0.62; 0.61; 0.60; 0.59; 0.58; 0.57; 0.56; 0.55; 0.54; 0.53; 0.52; 0.51; 0.50; 0.49; 0.48; 0.47; 0.46; 0.45; 0.44; 0.42; 0.40; 0.38; 0.36; 0.34; 0.32; 0.30; 0.28; 0.26; 0.24; 0.22; 0.20; 0.18; 0.16; 0.14; 0.12; 0.10; 0.09; 0.08; 0.07; 0.06; 0.005; 0.04; 0.03; 0.02; 0.01; 0.00.

[0077] By "lubricating composition" we mean a composition capable of reducing friction, and where appropriate heating, between two parts during operation, but also during machining.

[0078] In general, the lubricating composition according to the invention comprises a lubricating base and at least one additive including at least the antioxidant according to the invention as described above.

[0079] Preferably, the lubricating base is well known to those skilled in the art and may comprise at least one mineral base oil and / or one synthetic base oil.

[0080] A mineral base oil can be a paraffinic or naphthenic base oil.

[0081] A synthetic base oil can be an oil made from synthetic esters, polyalphaolefins (PAO), or polyalkyl glycol (PAG).

[0082] For example, the synthetic ester base oil may be produced from mono-hydroxy alcohols and mono-carboxylic acids, or from mono-hydroxy alcohols and dicarboxylic acids. Such esters are well known to those skilled in the art. They are described, for example, in U.S. Patent No. US 3,432,433. The alcohols and acids used to prepare the esters may contain from one to six functional groups, allowing the production of mono-, di-, tri- and tetra-, penta- and hexa-esters. Included are esters of alcohols, diols, triols and pentaerythritols, said alcohols or polyols having from 2 to 20 carbon atoms, and mono- and di-carboxylic acids having from 2 to 20 carbon atoms, preferably from 4 to 12 carbon atoms. Polyols include trimethylolpropane, pentaerythritol, dipentaerythritol, neopentyl glycol, tripentaerythritol, di-TMP and mixtures thereof.

[0083] The esters that may be contained in a lubricating composition according to the invention include monoesters originating from the reaction of linear or branched monocarboxylic acids with a chain length of 2 to 24 carbons, such as, for example, monoesters of octyl acetate, decyl acetate, octadecyl acetate, ethyl 2-hexyl caprylate / caproate, methyl myristate, butyl stearate, methyl oleate, as well as polyesters of dibutyl phthalate, dioctyl adipate, di-2-ethylhexyl azelate and ethylhexyl sebacate, polyesters, reaction of polyols with linear and / or branched monocarboxylic acids with 2 to 24 carbons and polycarboxylic acids with 2 to 40 carbons or polyesters, reaction of polycarboxylic acids of 2 to 40 carbons with monoalcohols of 1 to 24 carbons and polyols.The polyol ester type base oil may be an oil prepared from dipentaerythritol or technical pentaerythritol or trimethylol propane and a mixture of linear and / or branched carboxylic acids having from 4 to 24 carbon atoms. Technical pentaerythritol is a mixture which comprises approximately 85% to 92% by weight of monopentaerythritol and 8% to 15% by weight of dipentaerythritol. A typical commercial technical pentaerythritol contains approximately 88% by weight of monopentaerythritol and approximately 12% by weight of dipentaerythritol, based on the total weight of said ester base oil. Technical pentaerythritol may also contain a certain amount of tri- and tetra-pentaerythritol which are usually formed as by-products during the production of technical pentaerythritol.

[0084] The lubricating composition generally comprises other additives, other than said at least one antioxidant according to the invention.

[0085] These other additives may be selected from detergent agents, dispersing agents, anti-foaming agents, anti-corrosion agents, anti-wear agents, additives suitable for extreme pressures, hydrolysis stabilizing agents, friction modifiers or viscosity modifying agents. Such additives are well known to those skilled in the art and commonly available commercially.

[0086] Generally, said lubricating composition and / or said at least one antioxidant additive does not substantially comprise, preferably does not comprise, diphenylamine monomers (DPA), phenolic monomers and / or any other standard antioxidant (toxic and / or ecotoxic) such as those mentioned above in the description of the prior art. In certain embodiments, the lubricating composition used according to the invention or the antioxidant agent used according to the invention does not substantially comprise, preferably does not comprise, any antioxidant additive other than the oligomer and / or the polymer comprising at least one diphenylamine repeating unit of formula (I) and optionally at least one phenyl a-naphthylamine repeating unit of formula (II) according to the invention.

[0087] In general, the antioxidant additive according to the invention represents, by mass, relative to the total mass of antioxidant agents present in the lubricating composition, from 50% to 100%, preferably from 80% to 100%, and in particular from 90% to 100% and typically 100%. According to the invention, by "50% to 100%", is meant the following values ​​or any interval between these values: 50; 55; 60; 65; 70; 75; 80; 85; 90; 95; 100.

[0088] Said at least one antioxidant agent and generally said at least one oligomer and / or polymer comprising at least one diphenylamine repeating unit of formula (I) and optionally at least one phenyl a-naphthylamine repeating unit of formula (II) is present in the lubricating composition used in the present invention in an amount such as those conventionally used in the art. For example, they may be used in an amount of 0.1 to 10% by weight, preferably 0.5 to 5% by weight, typically 1 to 4% relative to the total weight of said lubricating composition.

[0089] According to the invention, by 0.1% to 10%, we mean the following values ​​or any interval between these values: 0.1; 0.2; 0.3; 0.4; 0.5; 0.6; 0.7; 0.8; 0.9; 1; 1.5; 2; 2.5; 3; 3.5; 4; 4.5; 5; 5.5; 6; 6.5; 7; 7.5; 8; 8.5; 9; 9.5; 10.

[0090] By way of example, the lubricating composition according to the invention comprises, by mass, relative to its total mass: - at least 90% (a) of said lubricating base; - from 1 to 5% of at least one antioxidant comprising at least said at least one oligomer and / or polymer comprising at least one diphenylamine repeating unit of formula (I) and optionally at least one phenyl a-naphthylamine repeating unit of formula (II); - from 1 to 5% of at least one anti-wear agent; - 0 to 3% pour point improver additive and - from 0.01 to 0.3% of at least one metal corrosion inhibitor.

[0091] The present invention can also be applied to a method for preserving the physicochemical and mechanical properties of a lubricating composition comprising: - preparing said lubricating composition, which preferably does not comprise diphenylamine monomers (DPA) or phenolic monomers, - incorporating into said lubricating composition an effective amount of at least one antioxidant comprising an oligomer and / or polymer comprising at least one diphenylamine repeating unit of formula (I) as defined above and optionally at least one phenyl a-naphthylamine repeating unit of formula (II) as defined above, said at least one antioxidant being capable of reducing and / or preventing the toxicity of said lubricating composition.

[0092] According to the invention, unless otherwise specified, the percentages indicated in the present application are percentages by mass.

[0093] In the present invention, the term "about" a V value means a range between 0.9xV and 1.1xV. In some embodiments, it means a range between 0.95xV and 1.05xV, in particular a range between 0.99xV and 1.01xV. EXAMPLES Example 1: QSAR toxicity study

[0094] The oligomers and / or polymers comprising at least one diphenylamine repeating unit of formula (I) and optionally at least one phenyl a-naphthylamine repeating unit of formula (II) according to the invention were studied and compared to other standard antioxidant compounds, in terms of QSAR modeling for neurotoxicity, reprotoxicity, mutagenicity and carcinogenicity. QSAR modeling protocol

[0095] The toxicity levels of different compounds used according to the invention and other standard antioxidants were evaluated by QSAR (quantitative structure-activity relationship) modeling. Selection of training and validation sets

[0096] A set of test molecules was defined with chemical structures compiled from several publicly available sources such as: HSBD (Hazardous Substances Data Bank), EPA (US Environmental Protection Agency), ECHA (European Chemicals Agency) and NTP (National Toxicology Program). Approximately 34,000 molecules were selected for this project including: 3245 compounds classified as neurotoxic compounds, 12609 compounds classified as reprotoxic compounds, 4084 compounds classified as mutagenic compounds, 12158 compounds classified as carcinogenic compounds and 1953 compounds, called non-toxic, classified as neither neurotoxic, nor reprotoxic, nor mutagenic, nor carcinogenic.

[0097] From this set of test molecules, two sets of molecules were defined: a training set and a validation set. To do this, the “leave one out” method was used. The set of test molecules was divided into two sets, one containing 90% of the test molecules and forming the training set; and the other, containing the remaining 10% of the test molecules, and forming the validation set. QSAR model performance

[0098] A generalized linear model (GLM) method was chosen to perform a quantitative structure-activity relationship (QSAR) approach. From the training set, GLM models were trained separately to discriminate chemical structures (i) between neurotoxic and non-neurotoxic compounds, (ii) between reprotoxic and non-reprotoxic compounds, (iii) between mutagenic and non-mutagenic compounds, and (iv) between carcinogenic and non-carcinogenic compounds. This approach resulted in four GLM models with 328, 313, 327, and 330 significant descriptors in the neurotoxic, reprotoxic, mutagenic, and carcinogenic training sets, respectively. During training, the performance of the QSAR models was measured by Receiver Operator Characteristic (ROC) curves and resulted in area under the curve (AUC) values ​​of 0.8831 for neurotoxicity prediction, 0.7967 for reprotoxicity prediction, 0.8444 for the prediction of mutagenicity and 0.8333 for the prediction of carcinogenicity.

[0099] To validate the robustness of the QSAR models, they were then used to predict (i) the neurotoxicity categories of the compounds in the validation set (i.e., neurotoxic / non-neurotoxic categorization), (ii) the reprotoxicity categories of the compounds in the validation set (i.e., reprotoxic / non-reprotoxic categorization), (iii) the mutagenicity categories of the compounds in the validation set (i.e., mutagenic and non-mutagenic categorization), and (iv) the carcinogenicity categories of the compounds in the validation set (i.e., carcinogenic and non-carcinogenic categorization). During validation, the performance of QSAR models was measured by area under the curve (AUC) values ​​and provided significant values ​​of 0.76 and above for the prediction of neurotoxicity, mutagenicity and carcinogenicity and provided significant values ​​of 0.70 and above for the prediction of reprotoxicity.

[0100] GLM-based QSAR models were then used to study the compounds according to the invention. Interpretation of results

[0101] Once the model is built on the training set, then validated with the validation set, it mathematically determines a statistical threshold value as a percentage on a statistical basis.

[0102] The statistical QSAR cutoff values ​​for the different toxicities tested are illustrated in Table 2 below: Table 2]

[0103] This statistical threshold is a first draft allowing to distinguish between non-toxic, moderately toxic and toxic molecules. However, it does not allow to completely exclude toxic molecules from non-toxic molecules (margin of error on the probability of the risk of toxicity). The Applicant thus refined its research and determined that a reduction of the statistical threshold by a delta of 30% for each model (neurotoxic QSAR, reprotoxic QSAR, etc.) made it possible to reliably guarantee the toxicity or not of the molecules tested. Indeed, this new threshold (statistical threshold -30%), makes it possible to indisputably exclude moderately toxic and residual toxic molecules from non-toxic molecules. Also, an intermediate fringe (non-zero probability of toxicity) including moderately toxic and / or toxic residual molecules was established in order to establish a more precise classification.

[0104] The classification refined by the Applicant is illustrated in Table 3 below. Table 3]

[0105] The compounds tested are numbered as follows (Table 4 below): Table 4] SUBSTITUTION SHEET (RULE 26) SUBSTITUTION SHEET (RULE 26) SUBSTITUTION SHEET (RULE 26)

[0106] Thus, the examples named A to H are according to the invention and the examples named 1 to 26 are comparative examples (standard antioxidants and antiozonants).

[0107] The results of QSAR modeling are illustrated in Table 5 below: Table 5]

[0108] As shown in Table 5 above, the antioxidants comprising an oligomer and / or polymer comprising at least one diphenylamine repeating unit and optionally at least one phenyl a-naphthylamine repeating unit according to the invention exhibit both very low neurotoxicity, reprotoxicity, mutagenicity and low carcinogenicity. On the contrary, the compounds comprising standard antiozonant antioxidants are generally highly toxic, whether in terms of neurotoxicity, reprotoxicity, mutagenicity and / or carcinogenicity. For example, 4-terbutyldiphenylamine (component of Irganox® L57, line 9 of the table) is assessed as particularly carcinogenic, neurotoxic and reprotoxic and thus confirms the importance of the ongoing evaluation on reprotoxicity (OECD 443) of this molecule commissioned by ECHA.It therefore appears essential to replace it with a low-toxicity, or even non-toxic, compound such as that proposed by the invention. As additional examples, alpha and beta PANs (examples 19 and 20) both present very high levels of relative probability of toxicity on the 4 QSAR models (C, M, R and N), which consequently make them compounds of particular potential concern.

[0109] This QSAR modeling test therefore demonstrates that the oligomers and / or polymers comprising at least one diphenylamine repeating unit and optionally at least one phenyl a-naphthylamine repeating unit according to the invention make it possible to prevent and / or reduce the toxicity of a rubber-based composition. Example 2: Protocol for assessing toxicity by in vivo tests on non-vertebrate organisms

[0110] In order to complement the QSAR modeling tests, the Applicant conducted in vivo tests on models called planarians, invertebrate microorganisms living in water with a cephalic sphere and an apparent neuronal system, used in the literature to evaluate the neurotoxicity, neurodevelopment and reprotoxicity of compounds of concern such as pesticides and other toxic organophosphorus compounds (Poirier et al. Médecine / Sciences (Paris) 2019; 35 (6-7):544-8 “The planarian, an original animal model for toxicology”; D. Hagstrom et al. Archives of toxicology, 2017 91 (8), 2837-2847; Zhang et al. TOXICOLOGICAL SCIENCES, 2018, 1-19; Ireland et al. Chemosphere, 2020, 253, 126718).

[0111] The tests are carried out under conditions close to those reported in the mentioned publication (Zhang et al. TOXICOLOGICAL SCIENCES, 2018, 1-19).

[0112] The operating conditions used are as follows: - Number of test concentrations per chemical: 5 - Concentration ranges: 0.22 mg / L - 22 mg / L in semi-logarithmic steps - Organism studied: Whole adult planarians - Test duration: 12 days with checkpoint assessment at 7 and 12 days - Control points: lethality, adhesion (production of sticky mucus by the skin causing the planarian to be stuck to a wall rather than floating), movement speed, rest (pro rata of resting time compared to time spent moving), phototaxis and "scrunching" (specific mode of movement nominally used by the planarian in case of danger, here excessive heat). - Number of replicas: 3

[0113] The methodology used is as follows All compounds are supplied as powders. An appropriate volume of 100% DMSO (Sigma) was added, as indicated on the tubes, to obtain a stock solution at 4.4 mg / ml (i.e., 200 times more concentrated than the maximum test concentration). Each replicate was prepared using a 48-well multi-screen culture tray following the same procedure as described in Zhang et al., Neurotoxicology and Teratology, 2019. [Table 6] *Oligomers containing mainly A and B: amino oligomeric mixture based on DODPA and OPAN (i.e.: including 0-5% monomers, 25-30% A dimers, 20-25% B trimers, 15-20% tetramers) obtained according to the method described in patent applications FR 2924 122. **Recorded behavioral disorders: adhesion (production of sticky mucus by the skin leading the planarian to be stuck to a wall rather than floating), movement speed, rest (pro rata of resting time compared to the time spent moving), phototaxis and “scrunching” (specific mode of movement nominally used by the planarian in case of danger, here excessive heat).

[0114] This test shows that the antioxidants according to the invention (mixture of compounds A and B) have low toxicity in vivo, particularly in comparison with the comparative antioxidants PAN alpha and 6PPD.

[0115] Of course, various other modifications may be made to the invention within the scope of the appended claims.

Claims

Demands 1. Use of at least one antioxidant in a lubricating composition, said at least antioxidant comprising at least one oligomer and / or polymer comprising at least one diphenylamine repeating unit of general formula (I) in which each of R1 to R10 is independently chosen from a hydrogen atom, an alkyl group which is a saturated, linear or branched hydrocarbon group comprising from 1 to 24 carbon atoms and an aralkyl group which is an alkyl group as described above in which at least one of the carbon atoms is substituted by a monocyclic or polycyclic aromatic hydrocarbon aryl group comprising from 5 to 14 carbon atoms, to reduce and / or prevent the toxicity of said lubricating composition.

2. Use according to claim 1, wherein the toxicity includes one or more of the following toxicities: neurotoxicity, reproductive toxicity, mutagenicity, acute toxicity, carcinogenicity, toxicity to the synthesis, degradation, transport and mode of action of hormones, and ecotoxicity.

3. Use according to claim 1 or 2, wherein said oligomer and / or polymer also comprises at least one phenyl α-naphthylamine repeating unit of general formula (II): in which each of R11 to R22 is independently chosen from a hydrogen atom and an alkyl group which is a saturated hydrocarbon group, linear or branched, comprising from 1 to 24 carbon atoms.

4. Use according to any one of the preceding claims, wherein the at least one diphenylamine of formula (I) is an alkylated diphenylamine in which at one, preferably two, from R1 to R10 is an alkyl or aralkyl group, such as a tert-butyl group or a tert-octyl group or an n-nonyl group.

5. Use according to any one of the preceding claims 1 to 4, wherein the at least one diphenylamine of formula (I) is an alkylated diphenylamine in which at least one, preferably two, of R1 to R5 is an alkyl or aralkyl group, such as a tert-butyl group or a tert-octyl group and at least one, preferably two, of R6 to R10 is an alkyl or aralkyl group, such as a tert-butyl group or a tert-octyl group.

6. Use according to any one of the preceding claims, wherein the diphenylamine of formula (I) is selected from the group consisting of N,N-diphenylamine, N,N-di-(p-tert-butylphenyl)amine, N,N-di-(p-tert-octylphenyl)amine, N-(p-tert-butylphenyl)-N-phenylamine, N-(p-tert-octylphenyl)-N-phenylamine, N-(p-tert-butylphenyl)-N-(p-tert-octylphenyl)amine, tert-butyl and / or tert-octylated diphenylamines, nonylated diphenylamines, and any mixture thereof.

7. Use according to any one of the preceding claims 3 to 6, wherein said oligomer and / or polymer comprising at least one diphenylamine repeating unit is selected from one or more of the following compounds: a di-t-octyl-diphenylamine dimer, a di-t-octyl-diphenylamine trimer, a trimer comprising two di-t-octyl-diphenylamine motifs and one N-(4-tert-octylphenyl)-1-naphthylamine motif, and the oligomer of the mixture N,N-diphenylamine, N,N-di-(p-tert-butylphenyl)amine, N,N-di-(p-tert-octylphenyl)amine, N-(p-tert-butylphenyl)-N-phenylamine, N-(p-tert-octylphenyl)-N-phenylamine, N-(p-tert-butylphenyl)-N-(p-tert-octylphenyl)amine.

8. Use according to any one of claims 3 to 7, wherein phenyl a-naphthylamine is N-(4-tert-octylphenyl)-1 -naphthylamine.

9. Use according to any one of the preceding claims 3 to 8, wherein the polymer and / or oligomer comprises in its structure only diphenylamine repeat motifs and optionally phenyl a-naphthylamine repeat motifs.

10. Use according to any one of the preceding claims 3 to 9, wherein the oligomer and / or polymer comprising at least one diphenylamine repeat unit of formula (I) and optionally at least one phenyl α-naphthylamine repeat unit of formula (II) has a QSAR value for measuring each of the following toxicities: neurotoxicity (neurostotoxic QSAR), reprotoxicity (reprotoxic QSAR), mutagenicity (mutagenic QSAR) and carcinogenicity (carcinogenic QSAR), corresponding to a statistical threshold value (%) subtracted from a delta of at least 30%, said statistical threshold value being determined, for each of said toxicities, by QSAR modeling according to the method described below in the experimental part. 1 1. Use according to any one of claims 1 to 10, to reduce and / or prevent the toxicity of a lubricating composition in an engine of a thermal vehicle.