Use of an antioxidant for reducing and / or preventing the toxicity of a lubricant 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 diphenylamine repeat unit for reducing and / or preventing the toxicity of said lubricant composition.

Description

TECHNICAL FIELD

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

[0002] Lubricating compounds are known to be primarily used to reduce friction between two moving parts (industrial machinery, motor vehicles, etc.). Introducing a lubricating compound between two parts reduces friction and its associated negative effects, such as wear, fatigue, corrosion, breakage, and so on. A lubricating compound is a balanced mixture of several components, generally consisting of a base oil (mineral or synthetic) and basic additives, such as anti-wear additives, antioxidants, and so forth.

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

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

[0005] Thus, a lubricating composition must, on the one hand, meet specific technical performance requirements to reduce friction between two moving parts, 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 applications and everyday 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 preservation of the physico-chemical properties of the latter.

[0007] To date, two main categories of antioxidants are used: aromatic amines, such as diphenylamine monomers ( DPAand phenolic compounds. Unfortunately, recent studies show that the toxicological profile of standard antioxidants, such as those based on aromatic amines, is evolving negatively, drastically and alarmingly, given the established dangers to humans and the environment (carcinogenic, mutagenic, or toxic to reproduction, known as "CMR" toxicity; aquatic / ecotoxic toxicity; bioaccumulation; and the classification of substances as Persistent, Bioaccumulative, and Toxic, known as "PBT"). This trend is accelerating due to international regulatory agencies pushing for increasingly precise and intensive characterization of chemicals produced in very large volumes.As an 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 industry of fluids and lubricants.

[0008] In particular, standard antioxidants and their proven toxicity(s) are listed in Table 1 below: [Table 1] Compound Denomination CASE NO. Toxicity (ECHA Information - 2021) Mixture of N,N-diphenylamine monomers Irganox ®< L57 CAS 68411-46-1 Is harmful to aquatic life with long-term effects (ecotoxic) https: / / echa.europa.eu / fr / substance-information / - / substanceinfo / 100.063.733 Ongoing study on reproductive toxicity (OECD 443) Bis(nonylphenyl)amine Irganox ®< L67 CAS 36878-20-3 Is harmful to aquatic life with long-term effects (ecotoxic) https: / / echa.europa.eu / fr / substance-information / - / substanceinfo / 100.048.393 Evaluation in 2021 for suspected mutagenicity and PBT N-phenyl-1-naphthylamine PAN-1 CAS 90-30-2 It is very toxic to aquatic life with long-term effects (ecotoxic), is harmful if swallowed (acute toxicity), can cause organ damage through prolonged or repeated exposure, and may also cause an allergic skin reaction. https: / / echa.europa.eu / fr / substance-information / - / substanceinfo / 100.001.803 4,4'-methylen-bis-(2,6-di-tert-butylphenol) Ethanox ®< 4702 or MEDBP CAS 118-82-1 Currently being evaluated as an endocrine disruptor and as a persistent, bioaccumulative and toxic substance (PBT substance) https: / / echa.europa.eu / fr / substance-information / - / substanceinfo / 100.003.891

[0009] The potential toxicity 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 show 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 (Northwest USA). The authors found that in this salmon, exposure to rainwater leads to acute mortality when adult salmon migrate to urban streams to reproduce due to 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 repeat motifs, are toxic (see beginning of page 3).

[0013] There is therefore a very urgent need, given the state of the art, to develop alternative antioxidant additives to the standard antioxidants mentioned above in order to manufacture lubricating compositions that are more respectful of humans and the environment, especially in the current context where existing 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 assessments are underway under the auspices of ECHA and ANSES, such as that of Irganox L67, which in the future is likely to evolve and undergo the same evolution and classification as its counterpart Irganox L57. Those skilled in the art are therefore left without satisfactory and safe formulation solutions, i.e., non-toxic ones, for applications that may be for the general public (for example, car engine oils) and sensitive for the environment (lost lubrication, leaks into the environment, water, and oceans... manual maintenance of machines and equipment, emission of vapors or aerosols due to the heat produced within the system...).

[0014] Therefore, there is an urgent and crucial need in the state of the art to develop alternative antioxidant additives for lubricating compositions that offer both a satisfactory antioxidant effect, while also increasing the level of safety (reducing hazard to humans) and reducing the environmental impact of the lubricating composition in which the antioxidant is incorporated, in the targeted application areas (automotive, industry, wind power, ships, energy production, agricultural and forestry environments, 2-stroke engine tools, etc.). DESCRIPTION OF THE INVENTION

[0015] In this context, the Applicant has focused on developing compounds that have both antioxidant properties, while also preventing and / or reducing the toxicity of a lubricant composition in which they are incorporated, compared 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 section below, it has notably demonstrated, surprisingly and unexpectedly, that once oligomerized and / or polymerized, the toxicity of diphenylamine monomers is drastically reduced. This allows the formation of oligomers and / or polymers comprising at least one diphenylamine repeating unit, exhibiting both antioxidant properties, suitable for various applications in lubricant compositions (vehicle engines, wind turbine gears, etc.), and low or even non-toxicity to humans and / or the environment. The present invention thus contradicts the teachings of document WO 2019 / 126751 mentioned above, which state that diphenylamine derivatives, including oligomers with diphenylamine repeating units, are toxic.

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

[0018] As mentioned above, the antioxidant properties of some of the compounds according to the invention have been demonstrated in the prior art, notably in documents FR 2 924 122, EP 0 734 432, and WO 2009 / 071857. Although the use of the compounds according to the invention has already been considered in the prior art as antioxidant additives, to the Applicant's knowledge, no study has demonstrated their non-toxicity and, consequently, their usefulness in preventing and / or reducing, or even eliminating, 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, reproductive toxicity, mutagenicity, or carcinogenicity, which reinforces their potential as an alternative to DPA or phenolic monomers as antioxidant agents in lubricating compositions.

[0019] Furthermore, the Applicant considers that testing the toxicity of antioxidants is not This is a clear measure for those skilled in the art. That's why she developed an effective and thorough methodology based on four models (C: carcinogenic, M: mutagenic, R: reprotoxic, and N: neurotoxic), coupled with in vivo biological measurement, to definitively test the overall toxicity of a compound. This methodology has notably highlighted the significantly reduced toxicity of the diphenylamine oligomers / polymers according to the invention compared to other common antioxidant compounds. This invention represents a unique solution to date, enabling lubricant formulators to offer high-performance, even very high-performance, and long-lasting products, meaning without the risk of their classifications changing to CMR (carcinogenic, mutagenic, or reprotoxic) 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 antioxidant comprising at least one oligomer and / or polymer comprising at least one diphenylamine repeating unit of general formula (I): in which each among R1 has R10is 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 from 5 to 14 carbon atoms, to reduce and / or prevent the toxicity of said lubricating composition in which it is incorporated with respect to that of antioxidants belonging to the family of diphenylamine monomers (DPA), and in which said antioxidant represents from 80% to 100% by mass relative to the total mass of antioxidants present in the lubricating composition.

[0021] Of course, the different features, variants and embodiments of the invention can be combined with each other in various ways as long as they are not incompatible or mutually exclusive.

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

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

[0024] The present invention is described in and by the attached claims.

[0025] The present invention thus relates to the 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 among R1 has R10 is chosen independently 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.

[0026] Antioxidant refers to 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.

[0027] According to the invention, the "toxicity" of a substance and / or composition means that said substance and / or composition exhibits 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 mammal / living being to be born, 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 h), by the administration or contact (topical application) of a single (possibly massive) dose or 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 introduction 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 adverse effects in the nervous system of a mammal / living being, such as humans or planarians; carcinogenicity, which is the propensity of a substance to cause / provoke the onset of cancer or contribute to its aggravation or development; toxicity to the synthesis, degradation, transport, and mode of action of hormones, as is the case with endocrine disruptors (indirect toxicity via the physiological changes they cause).

[0028] A compound with CMR characteristics (carcinogenic, mutagenic, or toxic to reproduction) thus presents various toxicities.

[0029] According to one feature of the invention, toxicity thus includes 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.

[0030] “By reducing” the toxicity of a lubricating composition, it is understood that said antioxidant at least 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 suitable and / or configured to decrease 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 antioxidant at least 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 / decrease the toxicity of a lubricating composition.

[0031] “Preventing” the toxicity of a lubricating composition means that said at least 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 that would be in contact with said lubricating composition.For example, neurotoxic symptoms can affect the central nervous system (CNS) and present with the following effects: headaches, loss of appetite, drowsiness, mood and personality disorders, cognitive impairments (learning and concentration difficulties), or affect the peripheral nervous system (PNS) and present with the following effects: motor impairments such as weakness, tremors, incoordination, seizures, etc., or sensory impairments such as hearing loss, color vision deficiencies, tinnitus, loss of balance, etc.; these effects may or may not be reversible depending on the degree of acute or chronic exposure in the mammal. For example, symptoms of acute toxicity may include skin irritation, allergic skin reactions, vomiting, etc.

[0032] In general, said at least 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 suitable for and / or configured to reduce and / or prevent the toxicity of a lubricating composition at the various stages of its life, namely its implementation, use and end of life.

[0033] 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 α-naphthylamine repeating unit of general formula (II): in which each among R11 has R22 is chosen independently from: a hydrogen atom and an alkyl group which is a saturated hydrocarbon group, linear or branched, comprising from 1 to 24 carbon atoms.

[0034] In the present invention, a "polymer" of at least one diphenylamine and optionally at least one phenyl α-naphthylamine is defined as a compound comprising the repetition of at least two diphenylamine motifs with optionally at least one phenyl α-naphthylamine motif.

[0035] In the present invention, an "oligomer" of at least one diphenylamine and optionally at least one phenyl α-naphthylamine is defined as a polymer of at least one diphenylamine and optionally at least one phenyl α-naphthylamine comprising between 2 and 15 repeating units, or a mixture of such compounds. It may, in particular, be a dimer, trimer, tetramer, pentamer, hexamer, heptamer, octamer, nonamer, decamer, and / or any mixture of such compounds. Preferably, the oligomer contains (by weight percentage) at least 70%, preferably 80%, and in particular 90% by mass of the dimer, trimer, tetramer, pentamer, or a mixture of such compounds.

[0036] By "repeat motif" diphenylamine or phenyl α-naphthylamine, we mean the fact that, in the final structure of the oligomer or polymer obtained according to the invention, there is at least one diphenylamine motif and at least one phenyl α-naphthylamine motif, or at least two diphenylamine motifs with possibly at least one phenyl α-naphthylamine motif.

[0037] The diphenylamine and phenyl α-naphthylamine repeating units can be positioned in any way relative to each other within the structure of the polymer or oligomer according to the invention. Thus, the polymer or oligomer may comprise, at least in a portion of its structure, a regular alternation of diphenylamine and phenyl α-naphthylamine repeating units. It may also comprise, at least in a portion of its structure, a random distribution of diphenylamine and phenyl α-naphthylamine repeating units. Finally, it may comprise, in at least a portion of its structure, a block comprising a single type of diphenylamine or phenyl α-naphthylamine repeating unit.

[0038] In one embodiment, the polymer and / or oligomer according to the invention comprises in its structure only diphenylamine and phenyl α-naphthylamine repeating units. In another embodiment, the polymer and / or oligomer according to the invention comprises in its structure only diphenylamine repeating units.

[0039] The term “diphenylamine” refers to a compound with the formula (I): in which each among R1 has R10 is chosen independently 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).

[0040] In one embodiment, at least one diphenylamine of formula (I) is an alkylated diphenylamine, that is to say that at least one among R1 has R10 is an alkyl or aralkyl group. In another embodiment, at least one among R1 has R5 is an alkyl or aralkyl group, and at least one among R6 has R10 is an alkyl or aralkyl group.

[0041] In general, each among R1 has R10 is chosen independently from: a hydrogen atom or an alkyl group which is a saturated hydrocarbon group, linear or branched 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.

[0042] In general, at least one, in particular at least two, and typically at least three substituents from among R1 has R10is an alkyl group (as defined below), the other substituents being a hydrogen atom. Generally fewer than nine, particularly fewer than six, and typically fewer than four of the substituents among R1 has 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, "fewer than nine" includes the following numbers and all intervals between these values: 9; 8; 7; 6; 5; 4; 3; 2; 1. By way of example, one or two substituents among R1 has R10 is an alkyl group, the other substituents being a hydrogen atom.

[0043] In the present invention, "alkyl" refers to 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 numbers of carbon atoms and all 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, we can mention in particular the methyl group, the ethyl group, the n-propyl group, the isopropyl group, the n-butyl group, the tert-butyl group, the isobutyl group, the n-pentyl group, the isopentyl group, the n-hexyl group, the cyclohexyl group, the n-heptyl group, the n-octyl group, the tert-octyl group, the iso-octyl group, the n-nonyl group, the n-decyl group, the n-undecyl group, the n-dodecyl group and the isododecyl group.In a particular embodiment, an alkyl group is chosen from the group consisting of the tert-butyl group and the tert-octyl group, or the n-nonyl group (nC9), and can be chosen for example from the group consisting of the tert-butyl group and the tert-octyl group.

[0044] In the present invention, "aralkyl" refers to 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, 1-methyl-1-phenylethyl, a styryl group (C6H5-CH=CH-), or a methylstyryl group.

[0045] In the present invention, the term "aryl group" refers to a monocyclic or polycyclic aromatic hydrocarbon group. Each aromatic or polyaromatic ring comprises 5 to 14 atoms. Examples of aryl groups include the phenyl group.

[0046] In one embodiment, the diphenylamine of formula (I) is chosen 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.

[0047] 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 can thus be a dimer, a trimer, a tetramer, or 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, by way of example, correspond to a dimer or a trimer of di-(p-tert-octylphenyl)amine ( DODPA ), alone or in mixtures.

[0048] In particular, when the oligomer comprising at least one diphenylamine repeating unit of general formula (I) according to the invention is a dimer, it has at least three, generally at least four, substituents among all the R1 to R10 substituents of the repeating unit of formula (I) forming the dimer that are not hydrogen atoms (the other substituents are thus hydrogen atoms). According to the invention, "at least three substituents among all the R1 to R10 substituents of the repeating unit of formula (I) forming the dimer" includes 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 R1 to R10 substituents forming the dimer. In general, these at least three substituents are preferably each an alkyl group, i.e.: a saturated hydrocarbon group, linear or branched, comprising from 1 to 24 carbon atoms, preferably 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 independently be a tert-butyl group, a tert-octyl group, or 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.As an example, one repeating motif of the dimer comprises at least one substituent from R1 to R10 that is not a hydrogen atom (and is preferably an alkyl group as defined above) and the other motif of the dimer comprises at least two substituents from R1 to R10 that are not a hydrogen atom (and is preferably an alkyl group as defined above).

[0049] In general, when the oligomer comprising at least one diphenylamine repeating unit of general formula (I) according to the invention is a trimer, it 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 from among all the R1 to R10 substituents forming the trimer. In particular, said at least one, preferably five, or even six substituents are generally each an alkyl group, i.e.: a saturated hydrocarbon group, linear or branched, comprising from 1 to 24 carbon atoms, preferably 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 independently be a tert-butyl group, 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 substituent(s) 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 among R1 to R10 that are alkyl groups as defined above (the other substituents being hydrogen atoms).Generally, the alkyl substituent(s) are independently distributed across the three diphenylamine repeating units of formula (I) of the trimer. Typically, each repeating unit of the trimer comprises at least one, and possibly two, alkyl substituents (the other substituents being hydrogen atoms).

[0050] The diphenylamines according to the invention can be presented individually, or in mixtures with each other. For example, they can be presented as 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, and nonylated diphenylamines.

[0051] Oligomers and / or polymers comprising at least one diphenylamine repeating motif of general formula (I) may correspond to the compounds exemplified below.

[0052] Phenyl α-naphthylamine, according to the present invention, refers to a compound of formula (II): in which each among R11 has R22 is chosen independently from: a hydrogen atom and an alkyl group which is a saturated hydrocarbon group, linear or branched, comprising from 1 to 24 carbon atoms.

[0053] In one embodiment, at least one among R11 has R22 is an alkyl group. In one embodiment, only one among R11 has R22 is an alkyl group, in particular a tert-octyl group.

[0054] In one particular embodiment, phenyl α-naphthylamine is N-(4-tert-octylphenyl)-1-naphthylamine, CAS number 4572-51-4 ( OPAN ).

[0055] In one embodiment of the invention, 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 at least one phenyl α-naphthylamine is N-(4-tert-octylphenyl)-1-naphthylamine ( OPAN ).

[0056] In another embodiment of the invention, at least one diphenylamine is di-(p-tert-octylphenyl)amine ( DODPA ) and at least one phenyl α-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, 1DODPA / 2OPAN, 3DODPA. According to one embodiment, said at least oligomer may correspond to a mixture of trimers, such as a mixture of 2DODPA / 1OPAN, 1DODPA / 2OPAN And 3DODPA.In particular, within this mixture, the oligomer 2DODPA / 1OPAN is predominant. In general, said at least oligomer comprises a mixture of trimers (such as 2DODPA / 1OPAN, 1DODPA / 2OPAN, 3DODPA), of tetramers, pentamers and hexamers.

[0057] The relative mass proportions of the two types of diphenylamine and phenyl α-naphthylamine motifs within the polymer or oligomer can vary widely from 0 / 100 to 100 / 0. Preferably, the relative mass proportion of diphenylamine / phenyl α-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.

[0058] The polymer or oligomer according to the present invention, forming said antioxidant at least according to the invention, can in particular be prepared according to the process described in patent application FR 2010199 filed by the Applicant, namely in a continuous reactor. Those skilled in the art can adjust the quantities of diphenylamine and phenyl α-naphthylamine to be introduced into the reactor according to, in particular, the desired structure of the oligomer or polymer to be synthesized and the required thermal characteristics. The polymer or oligomer according to the present invention, forming said antioxidant at least according to the invention, can also in particular be prepared according to the process described in document WO 2008 / 022028.

[0059] For the present invention, the Applicant has demonstrated the non-toxicity of said at least antioxidant comprising at least one oligomer and / or a polymer comprising at least one diphenylamine repeat motif of formula (I) and optionally at least one phenyl α-naphthylamine repeat motif of formula (II) according to the invention by QSAR modeling tests for neurotoxicity, reprotoxicity, mutagenicity and carcinogenicity.

[0060] In particular, the oligomer and / or polymer comprising at least one diphenylamine repeating unit of formula (I) and possibly at least one phenyl α-naphthylamine repeating unit of formula (II) exhibits a QSAR value for the measurement of 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 (quantitative structure-activity relationship) modeling according to the method described below in the experimental part,

[0061] 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).

[0062] According to one embodiment, the statistical threshold value (neurotoxic QSAR) as a percentage is typically 55%.

[0063] Preferably, the delta for the measurement of the neurotoxic QSAR is at least 45%, advantageously at least 55% and typically at least 53%.

[0064] In general, the oligomer and / or polymer comprising at least one diphenylamine repeat motif of formula (I) and possibly at least one phenyl α-naphthylamine repeat motif 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 neurotoxicity (neurotoxic QSAR).

[0065] 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.

[0066] According to another embodiment, the statistical threshold value (reprotoxic QSAR) as a percentage is typically 90%.

[0067] Preferably, the delta for the measurement of reprotoxic QSAR is at least 41%, advantageously at least 43% and typically at least 46%.

[0068] In general, the oligomer and / or polymer comprising at least one diphenylamine repeat motif of formula (I) and possibly at least one phenyl α-naphthylamine repeat motif of formula (II) has a percentage value (%) by QSAR modeling less than or equal to 65%, preferably less than or equal to 50% and typically less than or equal to 45% for the reprotoxicity measurement (reprotoxic QSAR).

[0069] 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.

[0070] According to another embodiment, the statistical threshold value (mutagenic QSAR) in percentage is typically 58%.

[0071] Preferably, the delta for the measurement of the mutagenic QSAR is at least 48%, advantageously at least 53% and typically at least 56%.

[0072] Generally, the oligomer and / or polymer comprising at least one diphenylamine repeat motif of formula (I) and possibly at least one phenyl α-naphthylamine repeat motif 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 mutagenicity measurement (mutagenic QSAR).

[0073] 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.

[0074] According to another embodiment, the statistical threshold value (QSAR carcinogenic) in percentage is typically 85%.

[0075] Preferably, the delta for the measurement of carcinogenic QSAR is at least 77%, advantageously at least 82% and typically at least 85%.

[0076] In general, the oligomer and / or polymer comprising at least one diphenylamine repeat motif of formula (I) and possibly at least one phenyl α-naphthylamine repeat motif 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 carcinogenic character measurement (carcinogenic QSAR).

[0077] 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.

[0078] By "lubricating composition" we mean a composition capable of reducing friction, and where applicable heating, between two parts in operation, but also during machining.

[0079] In general, the lubricating composition according to the invention comprises a lubricating base and at least one additive, of which at least the antioxidant according to the invention is described above.

[0080] Preferably, the lubricating base is well known to a person skilled in the art and may include at least one mineral base oil and / or one synthetic base oil.

[0081] A mineral base oil can be a paraffinic or naphthenic base oil.

[0082] A synthetic base oil can correspond to an oil based on synthetic esters, polyalphaolefins (PAO), or polyalkylglycol (PAG).

[0083] For example, synthetic ester-based base oils can be produced from monohydroxylated alcohols and monocarboxylic acids, or from monohydroxylated 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. 3,432,433. The alcohols and acids used to prepare the esters can contain from one to six functional groups, thus enabling the production of mono-, di-, tri-, tetra-, penta-, and hexa-esters. This includes esters of alcohols, diols, triols, and pentaerythritols, said alcohols or polyols having from 2 to 20 carbon atoms, and mono- and dicarboxylic acids having from 2 to 20 carbon atoms, preferably from 4 to 12 carbon atoms. Polyols include trimethylolpropane, pentaerythritol, dipentaerythritol, neopentylglycol, tripentaerythritol, di-TMP and mixtures thereof.

[0084] The esters that may be contained in a lubricating composition according to the invention include monoesters resulting from the reaction of monocarboxylic acids with chain lengths of 2 to 24 carbons, linear or branched, 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, di-octyl adipate, di-2-ethylhexyl azelate, and ethylhexyl sebacate, polyesters, the reaction of polyols with linear and / or branched monocarboxylic acids of 2 to 24 carbons and polycarboxylic acids of 2 to 40 carbons, or polyesters, the reaction of carboxylic polyacids of 2 to 40 carbons with monoalcohols of 1 to 24 carbons and polyols.The base oil of the polyol ester type 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, monopentaerythritol, and 8% to 15% by weight of dipentaerythritol. A conventional commercial technical pentaerythritol contains about 88% by weight of monopentaerythritol and about 12% by weight of dipentaerythritol, relative to the total weight of said base oil of the ester type. Technical pentaerythritol may also contain some tri- and tetrapentaerythritol, which are usually formed as byproducts during the production of technical pentaerythritol.

[0085] The lubricating composition generally includes other additives, other than said at least antioxidant according to the invention.

[0086] These other additives can be chosen from among detergents, dispersants, antifoaming agents, corrosion inhibitors, anti-wear agents, additives suitable for extreme pressures, hydrolysis stabilizers, friction modifiers, or viscosity modifiers. Such additives are well known to those skilled in the art and are readily available commercially.

[0087] Generally, said lubricating composition and / or said at least 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 prior art description. In some 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 polymer comprising at least one diphenylamine repeating unit of formula (I) and optionally at least one phenyl α-naphthylamine repeating unit of formula (II) according to the invention.

[0088] The antioxidant additive according to the invention represents, by mass, relative to the total mass of antioxidants present in the lubricant composition, 80% to 100%, and in particular 90% to 100% and typically 100%. According to the invention, "80% to 100%" means the following values ​​or any interval between these values: 80; 85; 90; 95; 100.

[0089] 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 α-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.

[0090] According to the invention, "0.1% to 10%" means 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.

[0091] 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; 1 to 5% of at least one antioxidant comprising at least said at least oligomer and / or polymer comprising at least one diphenylamine repeating unit of formula (I) and optionally at least one phenyl α-naphthylamine repeating unit of formula (II); 1 to 5% of at least one anti-wear agent; 0 to 3% of pour point enhancement additive and 0.01 to 0.3% of at least one metal corrosion inhibitor.

[0092] The present invention can also be applied to a method for preserving the physicochemical and mechanical properties of a lubricating composition comprising: prepare said lubricating composition, which preferably does not include diphenylamine monomers ( DPA ) or phenolic monomers, incorporate 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 α-naphthylamine repeating unit of formula (II) as defined above, said at least antioxidant being capable of reducing and / or preventing the toxicity of said lubricating composition.

[0093] According to the invention, unless otherwise specified, the percentages indicated in this application are percentages by mass.

[0094] In the present invention, the term "approximately" a value V designates an interval between 0.9xV and 1.1xV. In some embodiments, it designates an interval between 0.95xV and 1.05xV, in particular an interval between 0.99xV and 1.01xV. EXAMPLES Example 1 : QSAR Toxicity Study

[0095] The oligomers and / or polymers comprising at least one diphenylamine repeat motif of formula (I) and optionally at least one phenyl α-naphthylamine repeat motif of formula (II) according to the invention have been studied and compared to other standard antioxidant compounds, in terms of QSAR modeling for neurotoxicity, reprotoxicity, mutagenicity and carcinogenicity. QSAR modeling protocol

[0096] 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 games

[0097] A set of test molecules was defined with chemical structures compiled from several publicly available sources, including the HSBD (Hazardous Substances Data Bank), the EPA (US Environmental Protection Agency), the ECHA (European Chemicals Agency), and the 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.

[0098] From this set of test molecules, two sets of molecules were defined: a training set and a validation set. The "leave one out" method was used for this purpose. 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

[0099] A generalized linear model (GLM) method was chosen to implement 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 with328, 313, 327 and 330 respectively significant descriptors within neurotoxic, reprotoxic, mutagenic, and carcinogenic training sets. During training, the performance of the QSAR models was measured by Receiver Operator Characteristic (ROC) curves and yielded area under the curve (AUC) values ​​of 0.8831 for the prediction of neurotoxicity, of 0.7967 for the prediction of reproductive toxicity, of 0.8444 for the prediction of mutagenicity and 0.8333 for predicting carcinogenicity.

[0100] 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., the neurotoxic / non-neurotoxic categorization), (ii) the reprotoxicity categories of the compounds in the validation set (i.e., the reprotoxic / non-reprotoxic categorization), (iii) the mutagenicity categories of the compounds in the validation set (i.e., the mutagenic and non-mutagenic categorization), and (iv) the carcinogenicity categories of the compounds in the validation set (i.e., the carcinogenic and non-carcinogenic categorization). During validation, the performance of the QSAR models was measured by area under the curve (AUC) values ​​and yielded significant values ​​of 0,76 and more for the prediction of neurotoxicity, mutagenicity and carcinogenicity and provided significant values ​​of 0.70and more for the prediction of reproductive toxicity.

[0101] GLM-based QSAR models were then used to study the compounds according to the invention. Interpretation of the results

[0102] Once the model is built on the training set, and then validated with the validation set, it mathematically determines, on a statistical basis, a statistical threshold value as a percentage.

[0103] The statistical threshold values ​​(QSAR) for the different toxicities tested are illustrated in Table 2 below: [Table 2] Non-toxic and moderately toxic molecules (%) Toxic molecules (%) QSAR Neurotoxic < 55% ≥ 55 % QSAR Reprotoxic < 90% ≥ 90 % QSAR Mutagen < 58 % ≥ 58 % QSAR Carcinogen < 85 % ≥ 85 %

[0104] This statistical threshold is a first draft allowing for the distinction between non-toxic, moderately toxic, and toxic molecules. However, it does not completely exclude toxic molecules from non-toxic molecules (margin of error on the probability of toxicity risk). The Applicant therefore refined its research and determined that a 30% reduction in the statistical threshold for each model (neurotoxic QSAR, reprotoxic QSAR, etc.) reliably guarantees the toxicity of the tested molecules. Indeed, this new threshold (statistical threshold -30%) definitively separates moderately toxic and residual toxic molecules from non-toxic molecules. Furthermore, an intermediate range (non-zero probability of toxicity) including moderately toxic and / or toxic residual molecules was established to create a more precise classification.

[0105] The ranking refined by the Applicant is illustrated in Table 3 below. [Table 3] Slightly toxic (%) Moderately toxic (intermediate fringe) (%) Highly Toxic (%) QSAR Neurotoxic < 25 25 ≤ QSAR < 55 55 ≤ QSAR ≤ 100 QSAR Reprotoxic < 60 60 ≤ QSAR < 90 90 ≤ QSAR ≤ 100 QSAR Mutagen < 28 28 ≤ QSAR < 58 58 ≤ QSAR ≤ 100 QSAR Carcinogen < 55 55 ≤ QSAR < 85 85 ≤ QSAR ≤ 100

[0106] The compounds tested are numbered as follows (Table 4 below): [Table 4] Ex. Chemical name CAS NO. Formula developed A p,p'-dioctyldiphenylamine dimer or DODPA dimer 35972-72-6 B Trimer: 2DODPA / 1 OPAN - C 4- Dimer N onyl-n-(4-nonylphenyl)aniline or [di(nC9)DPA] 2 - D (H,isoC8 DPA)(isoC4,isoC8 DPA) - E (isoC4,isoC8 DPA) 2 - F (DODPA)(OPAN) - G (H,isoC8 DPA)(isoC4,isoC8 DPA)(di-isoC8 DPA) - H (DODPA) 3 - I p,p'-dioctyldiphenylamine ( DODPA ) 15721-78-5 2 N-(4-tert-octylphenyl)-1-naphthylamine ( OPAN ) 4572-51-4 3 4,4'-Methylene-bis-(2,6-di-tert-butylphenol) ( MEDBP ) 118-82-1 4 Octadécyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanoate Irganox ®< L107 2082-79-3 R1 = nC 18 H 37 5 Octyl 3-[4-hydroxy-3,5-bis(2-methyl-2-propanyl)phenyl]propanoate 125643 -61-0 R1 = nC 8 H 17 6 2-ethylhexyl 3-[4-hydroxy-3,5-bis(2-methyl-2-propanyl)phenyl]propanoate Irganox ®< L145 144429 -84-5 R1 = 2Ethylhexyl 7 1,6-Hexanediyl bis{3-[4-hydroxy-3,5-bis(2-methyl-2-propanyl)phenyl]propanoate} Irganox ®< L109 35074-77-2 8 2-[(2-{[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanoyl]oxy}ethyl)sulfanyl]ethyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanoate Irganox ®< L115 41484-35-9 9 4-tert-butyldiphenylamine as a component of Irganox ®< L57 (68411-46-1) 4496-49-5 10 Biphenyl-4-ylamine 92-67-1 11 Nonylphenol 25154-52-3 mixture of positional isomers 12 4-Methylbenzene-1,3-diamine 95-80-7 13 2-(2H-benzotriazol-2-yl)-4,6-ditertpentylphenol 25973-55-1 14 4-tert-butylphenol 98-54-4 15 3,3-bis(4-hydroxyphenyl)-1,3-dihydro-2-benzofuran-1-one 77-09-8 16 2,4-Dinitrotoluene 121-14-2 17 4-[(4-aminophenyl)methyl]aniline ( MDA ) 101-77-9 18 N-phenylaniline ("Diphenylamine") DPA ) 122-39-4 19 N-phenylnaphthalene-1-amine (PAN (alpha)) 90-30-2 20 N-phenylnaphthalene-2-amine (PAN (beta)) 135-88-6 21 2-tert-butyl-6-[(3-tert-butyl-2-hydroxy-5-methylphenyl)methyl]-4-methylphenol 119-47-1 22 N-(1,3-Dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD) 793-24-8 23 N-Isopropyl-N'-phenyl-p-phenylenediamine (IPPD) 101-72-4 24 N,N'-Bis(1,4-dimethylpentyl)-P-phenylenediamine (77PD) 3081-14-9 25 Bis[4-(2-phenyl-2-propyl)phenyl]amine (NAUGARD ®< 445) 10081-67-1 26 4- N onyl-n-(4-nonylphenyl)aniline 24925-59-5

[0107] Thus, the examples named A to H are according to the invention and the named examples 1 à 26are comparative examples (standard antioxidants and anti-ozonants).

[0108] The results of the QSAR modeling are illustrated in Table 5 below:

[0109] As shown in Table 5 above, antioxidants comprising an oligomer and / or polymer including at least one diphenylamine repeating unit and optionally at least one phenyl α-naphthylamine repeating unit according to the invention exhibit very low neurotoxicity, reproductive toxicity, mutagenicity, and low carcinogenicity. In contrast, the compounds composing standard anti-ozonant antioxidants are generally highly toxic, whether in terms of neurotoxicity, reproductive toxicity, mutagenicity, and / or carcinogenicity. For example, 4-tert-butyldiphenylamine (a component of Irganox®< L57, line 9 of the table) is assessed as particularly carcinogenic, neurotoxic, and reproductive toxic, thus confirming the importance of the ongoing reproductive toxicity assessment (OECD 443) of this molecule commissioned by the ECHA.It therefore appears essential to replace it with a weakly, or even non-toxic, compound such as that proposed by the invention. As further examples, alpha and beta PANs (examples 19 and 20) both exhibit very high levels of relative probability of toxicity on the four QSAR models (C, M, R, and N), making them potentially particularly concerning compounds.

[0110] This QSAR modelling test therefore demonstrates that oligomers and / or polymers comprising at least one diphenylamine repeat motif and possibly at least one phenyl α-naphthylamine repeat motif according to the invention make it possible to prevent and / or reduce the toxicity of a rubber-based composition. Example 2: Toxicity assessment protocol using in vivo tests on non-vertebrate organisms

[0111] In order to complement the QSAR modelling tests, the Applicant conducted tests in vivoon models called planarians, invertebrate microorganisms living in water possessing a cephalic sphere and an apparent neuronal system, used in the literature to assess the neurotoxicity, neurodevelopment and reprotoxicity of compounds of concern such as pesticides and other toxic organophosphate 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).

[0112] The tests are carried out under conditions close to those reported in the publication mentioned (Zhang et al. TOXICOLOGICAL SCIENCES, 2018, 1-19).

[0113] 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 assessment of control points at 7 and 12 days. Control points: lethality, adhesion (production of sticky mucus by the skin causing the planarian to adhere to a surface rather than float), movement speed, resting (proportion of resting time to movement time), phototaxis, and scrunching (specific locomotion method nominally used by the planarian when threatened, in this case, by excessive heat). Number of replicates: 3

[0114] The methodology used was as follows: All compounds were supplied in powder form. An appropriate volume of 100% DMSO (Sigma) was added, as indicated on the tubes, to obtain a stock solution of 4.4 mg / ml (200 times more concentrated than the maximum test concentration). Each replica 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] Ex. Concentration from which behavioral disturbances potentially linked to cognitive disorders of the planarian are observed** Concentration from which significant planarian mortality is observed according to Zhang et al., Neurotoxicology and Teratology, 2019 A+ B* > 22 mg / L > 22 mg / L 19 2.2–3.9 mg / L 6.9 mg / L 22 1.5 mg / L 4.8 mg / L *Oligomers containing predominantly A and B: oligomeric amine mixture based on DODPA and OPAN (i.e., of which 0-5% are monomers, 25-30% are A dimers, 20-25% are B trimers, and 15-20% are tetramers) obtained according to the method described in the patent applications FR 2 924 122 . **Recorded behavioral disorders: adhesion (production of sticky mucus by the skin leading the planarian to be stuck to a wall rather than floating), speed of movement, rest (proportion of rest 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).

[0115] This test shows that the antioxidants according to the invention (mixture of compounds A and B) exhibit low in vivo toxicity, particularly in comparison with the comparative antioxidants PAN alpha and 6PPD.

[0116] Of course, various other modifications can be made to the invention within the scope of the attached claims.

Claims

1. 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 linear or branched saturated hydrocarbon group comprising 1 to 24 carbon atoms and an aralkyl group which is an alkyl group as described above, at least one of the carbon atoms is substituted by a monocyclic or polycyclic aromatic hydrocarbon aryl group comprising 5-14 carbon atoms, for reducing and / or preventing the toxicity of said lubricating composition in which it is incorporated with respect to that of antioxidants belonging to the family of diphenylamine (DPA) monomers and in which, said antioxidant comprising at least one oligomer and / or polymer comprising at least one diphenylamine repeating unit of general formula (I) represents, by weight, relative to the total weight of the antioxidant agents present in the lubricating composition, from 80% to 100%.

2. Use according to claim 1, wherein the toxicity 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.

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): wherein each of R11 to R22 is independently selected from a hydrogen atom and an alkyl group which is a linear or branched saturated hydrocarbon group comprising 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 wherein at least one, preferably two, of 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 wherein 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-butylated 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 dimer of di-t-octyl-diphenylamine, a trimer of di-t-octyl-diphenylamine, a trimer comprising two di-t-octyl-diphenylamine units and an N-(4-tert-octylphenyl)-1-naphthylamine unit, and the oligomer of the 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 mixture.

8. Use according to any one of claims 3 to 7, wherein the phenyl α-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 repeating units and optionally phenyl α-naphthylamine repeating units.

10. Use according to one of the preceding claims 3 to 9, wherein the oligomer and / or the polymer comprising at least one diphenylamine repeating unit of formula (I) and optionally at least one phenyl α-naphthylamine repeating unit of formula (II) has a QSAR value for measuring 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 modelling according to the method described below in the experimental part.

11. Use according to any one of claims 1 to 10, for reducing and / or preventing the toxicity of a lubricating composition in an engine of a combustion vehicle.

12. Use according to any one of claims 1 to 11, wherein said antioxidant comprising at least one oligomer and / or polymer comprising at least one diphenylamine repeating unit of general formula (I) represents, by weight, relative to the total weight of antioxidant agents present in the lubricating composition, from 90% to 100%.

13. Use according to any one of claims 1 to 12, wherein said antioxidant comprising at least one oligomer and / or polymer comprising at least one diphenylamine repeating unit of general formula (I) represents, 100% by weight, relative to the total weight of antioxidant agents present in the lubricating composition.

14. Use according to any one of claims 1 to 13, wherein said at least one antioxidant comprising said at least one oligomer and / or polymer comprising at least one diphenylamine repeating unit of formula (I) and optionally at least one phenyl α -naphthylamine repeating unit of formula (II) is present in the lubricating composition in an amount of 0.1 to 10% by weight, preferably 0.5 to 5% by weight, typically 1 to 4% by weight, relative to the total weight of antioxidants present in said lubricating composition.

15. Use according to any of claims 1 to 14, wherein said lubricant composition and / or said at least one antioxidant does not comprise diphenylamine (DPA) monomers or phenolic monomers.

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