RUBBER COMPOSITION BASED ON HIGHLY SATURATED DIENEIC ELASTOMER AND A REINFORCING RESIN

Abstract

The invention relates to a rubber composition exhibiting an improved stiffness-hysteresis compromise and to a tire comprising this composition. The composition is based on at least one elastomeric matrix comprising more than 50 parts per cent of at least one copolymer containing ethylene units and 1,3-diene units, the ethylene units in the copolymer representing between 50% and 95% by mole of the monomer units of the copolymer; a reinforcing filler; a vulcanizing system;of 1 to 30 parts per annum of epoxy resin and between 1 and 15 parts per an amine hardener comprising at least two primary amine functions, located on at least one six-atom aromatic ring, said at least one six-atom aromatic ring comprising at least one primary amine function, and at least two Ri radicals, identical or different, selected from the group consisting of linear or branched C1-C6 alkyl radicals, halogens, ethers, tertiary amines, thioethers, ketones, esters, and amides, substituted by linear or branched C1-C6 alkyl radicals, such that the at least one six-atom aromatic ring does not include a hydrogen atom located in the ortho position with respect to the primary amine functions, said amine hardener comprising at least one second primary amine function located on said at least one six-atom aromatic ring or on a possible second aromatic ring six atoms of said amine hardener;

Description

Title of the invention: RUBBER COMPOSITION BASED ON A HIGHLY SATURATED DIENIC ELASTOMER AND A REINFORCING RESIN

[0001] The present invention relates to rubber compositions intended in particular for the manufacture of tires or semi-finished products for tires.

[0002] Tire layers such as the tread or inner layers must comply with a large number of technical requirements, often contradictory, including low rolling resistance, high wear resistance, good road behavior, and a good level of material cohesion.

[0003] In order to ensure good rigidity, particularly indicative of road handling, it is known to use rubber compounds with high reinforcing load ratios. However, it is known that increasing the load ratio can negatively impact the hysteresis properties and therefore the rolling resistance of the tires.

[0004] High rigidity can also be achieved by incorporating certain reinforcing resins as disclosed in WO 02 / 10269, which proposes rubber compositions exhibiting high rigidity under small tire deformations. Resistance to small deformations is one of the properties that a tire must possess to withstand the stresses to which it is subjected.

[0005] Furthermore, it remains important that the proposed solutions to this problem do not negatively impact other properties of the rubber compound, particularly hysteresis. Indeed, the use of a hysteretic compound in a tire can lead to an increase in the tire's internal temperature, which can result in a decrease in tire durability. In light of the above, there is an ongoing objective to provide rubber compounds that offer an improved compromise between stiffness and hysteresis. Naturally, it is advantageous that improving this compromise does not come at the expense of other properties of the compound, in particular mechanical properties such as elongation at break and tensile strength, which are especially important properties in many internal tire layers.

[0006] Thus, there is a need to find ways to improve the endurance of tires comprising high-stiffness compounds without penalizing hysteresis, or even improving it, and without penalizing the mechanical properties of the composition.

[0007] Continuing its research, the Applicant unexpectedly discovered that the combined use of highly saturated diene elastomer and a curing system based on epoxy resin and a particular amine hardener makes it possible to further improve the aforementioned performance compromise.

[0008] Thus, the invention relates to a rubber composition based on at least:

[0009] - an elastomeric matrix comprising more than 50 parts per unit of at least one copolymer containing ethylene units and 1,3-diene units, the ethylene units in the copolymer representing between 50% and 95% by mole of the monomer units of the copolymer, - a reinforcing load, - a vulcanization system, - from 1 to 30 pieces of epoxy resin, - between 1 and 15 parts of an amine hardener comprising at least two primary amine functions, located on at least one six-atom aromatic ring, said at least one six-atom aromatic ring comprising: ° at least one primary amine function, and ° at least two Ri radicals, identical or different, chosen from the group consisting of linear or branched Ci-C6 alkyl radicals, halogens, ethers, tertiary amines, thioethers, ketones, esters and amides, substituted by linear or branched Ci-C6 alkyl radicals, such that at least one six-atom aromatic ring does not contain a hydrogen atom located in an ortho position relative to the primary amine functions, said amine hardener comprising at least one second primary amine function located on said at least one six-atom aromatic ring or on a possible second six-atom aromatic ring of said amine hardener.

[0010] It also relates to a tire comprising a composition according to the invention. I- DEFINITIONS

[0011] The expression "composition based on" means a composition comprising the mixture and / or the in situ reaction product of the different constituents used, some of these constituents being able to react and / or being intended to react with each other, at least partially, during the different phases of manufacturing the composition; the composition can thus be in a totally or partially crosslinked state or in a non-crosslinked state.

[0012] By "elastomer matrix", we mean all the elastomers in the composition, including the copolymer defined below.

[0013] Unless otherwise specified, the unit rates resulting from the insertion of a monomer in a copolymer are expressed as a molar percentage relative to the total number of monomer units in the copolymer.

[0014] The expression "part by weight per hundred parts by weight of elastomer" (or pce) is to be understood in the context of the present invention as the part, by mass per hundred parts of elastomer present in the rubber composition considered.

[0015] In the present, unless expressly stated otherwise, all percentages (%) indicated are percentages (%) by mass.

[0016] On the other hand, any interval of values ​​designated by the expression "between a and b" represents the domain of values ​​from greater than a to less than b (i.e., excluding the bounds a and b), while any interval of values ​​designated by the expression "from a to b" means the domain of values ​​from a to b (i.e., including the strict bounds a and b). In the present case, when an interval of values ​​is designated by the expression "from a to b", the interval represented by the expression "between a and b" is also and preferably designated.

[0017] The compounds mentioned in the description may be of fossil origin or bio-based. In the latter case, they may be partially or totally derived from biomass or obtained from renewable raw materials derived from biomass. Similarly, the compounds mentioned may also come from the recycling of materials already in use, that is to say, they may be partially or totally derived from a recycling process, or obtained from raw materials themselves derived from a recycling process. This includes, in particular, polymers, plasticizers, fillers, etc.

[0018] Unless otherwise indicated, all glass transition temperature values ​​“Tg” described herein are measured in a known manner by DSC (Differential Scanning Calorimetry) according to ASTM D3418 (1999). II- DESCRIPTION OF THE INVENTION II-1 Elastomer Matrix

[0019] According to the invention, the elastomeric matrix comprises more than 50 parts of at least one copolymer containing ethylene units and 1,3-diene units, the ethylene units in the copolymer representing between 50% and 95% by mole of the monomer units of the copolymer (hereinafter referred to as "the copolymer").

[0020] The term "copolymer containing ethylene units and 1,3-diene units" means any copolymer comprising, within its structure, at least ethylene units and 1,3-diene units. The copolymer may thus comprise monomer units other than ethylene units and 1,3-diene units. For example, the copolymer may also comprise alpha-olefin units, in particular alpha-olefin units having from 3 to 18 carbon atoms, advantageously having from 3 to 6 carbon atoms. For example, alpha-olefin units can be chosen from the group consisting of propylene, butene, pentene, hexene or mixtures thereof.

[0021] In a known manner, the expression "ethylene unit" refers to the -(CH2-CH2)- motif resulting from the insertion of ethylene into the elastomer chain.

[0022] In a known manner, the expression "1,3-diene unit" refers to units resulting from the insertion of 1,3-diene by a 1,4 addition, a 1,2 addition or a 3,4 addition in the case of a substituted diene such as isoprene for example.

[0023] Preferably, the 1,3-diene units are selected from the group consisting of butadiene units, isoprene units, and mixtures of these 1,3-diene units. In particular, the 1,3-diene units of the copolymer may be 1,3-diene units having 4 to 12 carbon atoms, for example, 1,3-butadiene, 2-methyl-1,3-butadiene (or isoprene) units. Even more preferably, the 1,3-diene units are, for more than 50% by mole, or preferably exclusively, 1,3-butadiene units.

[0024] In the copolymer, the ethylene units represent between 50% and 95% by mole of the monomer units of the copolymer. Advantageously, the ethylene units in the copolymer represent between 55% and 90%, preferably from 60% to 90%, preferably from 70% to 85%, by mole of the monomer units of the copolymer.

[0025] Advantageously, the copolymer is a copolymer of ethylene and a 1,3-diene (preferably 1,3-butadiene), that is to say, according to the invention, a copolymer consisting exclusively of ethylene units and 1,3-diene units (preferably 1,3-butadiene).

[0026] When the copolymer is a copolymer of ethylene and a 1,3-diene, it advantageously contains units of formula (I) and / or (II). The presence of a saturated 6-member cyclic motif, 1,2-cyclohexanediyl, of formula (I) as a monomer unit in the copolymer can result from a series of very specific insertions of ethylene and 1,3-butadiene into the polymer chain during its growth. -CH2-CH(CH=CH2)- (II)

[0027] For example, the copolymer of ethylene and a 1,3-diene may be devoid of formula units (I). In this case, it preferably contains formula units (II).

[0028] When the copolymer of ethylene and a 1,3-diene comprises units of formula (I) or units of formula (II) or units of formula (I) and units of formula (II), the molar percentages of units of formula (I) and units of formula (II) in the copolymer, respectively o and p, preferably satisfy the following equation (eq. 1), more preferably than equation (eq. 2), o and p being calculated on the basis of all the monomer units of the copolymer. 0 < o+p < 25 (eq. 1) 0 < o+p < 20 (eq. 2)

[0029] According to the invention, the copolymer, preferably the copolymer of ethylene and a 1,3-diene (preferably of 1,3-butadiene), is a statistical copolymer.

[0030] Advantageously, the number-average mass (Mn) of the copolymer, preferably of the copolymer of ethylene and a 1,3-diene (preferably of 1,3-butadiene) is in the range of 100,000 to 300,000 g / mol, preferably of 150,000 to 250,000 g / mol.

[0031] The Mn of the copolymer is determined in a known manner, by size exclusion chromatography (SEC) as described in point IV-1 below.

[0032] The copolymer can be obtained by various synthetic methods known to those skilled in the art, particularly depending on the desired microstructure of the copolymer. Generally, it can be prepared by copolymerization of at least one diene, preferably a 1,3-diene, even more preferably 1,3-butadiene, and ethylene, using known synthetic methods, particularly in the presence of a catalytic system comprising a metallocene complex. Examples include catalytic systems based on metallocene complexes, which are described in documents EP 1 092 731, WO 2004035639, WO 2007054223, and WO 2007054224 on behalf of the Applicant. The copolymer, including when statistical, can also be prepared by a process using a preformed catalytic system such as those described in documents WO 2017093654 Al, WO 2018020122 Al and WO 2018020123 AL

[0033] The copolymer may consist of a mixture of copolymers containing ethylene units and 1,3-diene units which differ from each other by their microstructures and / or by their macrostructures.

[0034] According to the invention, the elastomeric matrix may comprise at least one other diene elastomer, which is not the copolymer as defined above, but this is not necessary. Thus, preferably, the proportion of the at least one copolymer is in the range of 60 to 100 parts per cent, preferably 80 to 100 parts per cent. Advantageously, the at least one copolymer containing ethylene units and 1,3-diene units is the only elastomer in the composition, i.e., it represents 100% by mass of the elastomeric matrix.

[0035] By "diene" elastomer (or indistinctly rubber), whether natural or synthetic, is to be understood in a known way as an elastomer consisting at least in part (i.e., a homopolymer or a copolymer) of diene monomer units (monomers bearing two carbon-carbon double bonds, conjugated or not). This definition includes the copolymer containing ethylene units and 1,3-diene units.

[0036] When the elastomeric matrix comprises at least one other diene elastomer, which is not the copolymer containing ethylene units and 1,3-diene units, the at least one other elastomer may be, for example, selected from the group consisting of polybutadienes (BR), natural rubber (NR), synthetic polyisoprenes (IR), butadiene copolymers, isoprene copolymers, and mixtures of these elastomers. Butadiene copolymers are particularly selected from the group consisting of butadiene-styrene copolymers (SBR). II-2 Reinforcing Load

[0037] The composition according to the invention advantageously comprises a reinforcing filler, known for its ability to reinforce a rubber composition usable for the manufacture of tires. Such a reinforcing filler typically consists of particles whose average size (by mass) is less than one micrometer, generally less than 500 nm, most often between 20 and 200 nm, and in particular and more preferably between 20 and 150 nm.

[0038] The reinforcing filler may comprise carbon black, silica, or a mixture thereof. Advantageously, the reinforcing filler of the composition according to the invention comprises more than 50% by mass, preferably more than 80% by mass, of carbon black. Even more preferably, the reinforcing filler consists exclusively of carbon black, that is to say, carbon black represents 100% by mass of the reinforcing filler.

[0039] The blacks usable within the scope of the present invention can be any black conventionally used in tires or their treads (so-called tire-grade blacks). Among the latter, special mention should be made of reinforcing carbon blacks of the 100, 200, and 300 series, or blacks of the 500, 600, or 700 series (ASTM grades), such as NI 15, N134, N234, N326, N330, N339, N347, N375, N550, N683, and N772 blacks. These carbon blacks can be used in isolation, as commercially available, or in any other form, for example, as a carrier for certain rubber additives used. Carbon blacks could for example already be incorporated into the diene elastomer, in particular isoprene in the form of a masterbatch (see for example applications WO 97 / 36724 or WO 99 / 16600).

[0040] Among the aforementioned carbon blacks, those having a specific surface area BET in the range of 100 to 160 m2 / g, preferably 124 to 150 m2 / g, are particularly preferred.

[0041] The specific surface area BET of carbon blacks is measured according to standard D6556-2016 [multipoint method (minimum 5 points) - gas: nitrogen - range of relative pressure P / PO: 0.1 to 0.3].

[0042] Any type of precipitated silica may be suitable as a silica, in particular highly dispersible precipitated silica (known as "HDS" for "highly dispersible" or "highly dispersible silica"). These precipitated silicas, whether highly dispersible or not, are well known to those skilled in the art. Examples include the silicas described in applications WO03 / 016215-A1 and WO03 / 016387-A1. Among the commercial HDS silicas, one can notably use the “Ulsil ® 5000GR”, “Ulsil ® 7000GR” silicas from the company Evonik, the “Zeosil ® 1085GR”, “Zeosil® 1115 MP”, “Zeosil® 1165MP”, “Zeosil® Premium 200MP”, “Zeosil® HRS 1200 MP” silicas from the Solvay Company.As non-HDS silica, the following commercial silicas may be used: “Ultrasil® VN2GR”, “Ultrasil® VN3GR” from Evonik, “Zeosil® 175GR” from Solvay, “Hi-Sil EZ120G(-D)”, “Hi-Sil EZ160G(-D)”, “Hi-Sil EZ200G(-D)”, “Hi-Sil 243LD”, “Hi-Sil 210”, “Hi-Sil HDP 320G” from PPG.

[0043] To couple the silica to the diene elastomer, a coupling agent (or bonding agent) that is at least bifunctional can be used in a well-known manner to ensure sufficient chemical and / or physical connection between the inorganic filler (surface of its particles) and the diene elastomer. Organosilanes or polyorganosiloxanes that are at least bifunctional are used in particular. "Bifunctional" means a compound having a first functional group capable of interacting with the inorganic filler and a second functional group capable of interacting with the diene elastomer.For example, such a bifunctional compound may comprise a first functional group comprising a silicon atom, said first functional group being capable of interacting with the hydroxyl groups of an inorganic charge, and a second functional group comprising a sulfur atom, said second functional group being capable of interacting with the diene elastomer.

[0044] Preferably, when used, the organosilanes are chosen from the group consisting of polysulfide organosilanes (symmetric or asymmetric) such as bis(3-triethoxysilylpropyl) tetrasulfide, abbreviated TESPT and marketed under the name "Si69" by Evonik, or bis-(triethoxysilylpropyl) disulfide, abbreviated TESPD and marketed under the name "Si75" by Evonik, polyorganosiloxanes, mercaptosilanes, and blocked mercaptosilanes, such as S-(3-(triethoxysilyl)propyl) octanethioate, marketed by Momentive under the name "NXT Silane". More preferably, the organosilane is a polysulfide organosilane.

[0045] When a coupling agent is used to join silica to the elastomer, the amount of coupling agent can easily be adjusted by those skilled in the art. Typically, the amount of coupling agent ranges from 0.5% to 15% by weight relative to the quantity of silica.

[0046] The reinforcing filler content can easily be adjusted by a person skilled in the art according to the intended use of the rubber compound. Advantageously, the reinforcing filler content in the compound according to the invention is in the range of 10 to less than 100 parts per annum, preferably from 15 to 90 parts per annum.

[0047] Preferably, the carbon black content in the composition according to the invention is in the range of 10 to less than 100 parts per annum, preferably from 15 to 90 parts per annum, and the composition does not include any filler other than carbon black or includes less than 10 parts per annum, preferably less than 5 parts per annum, preferably again the composition does not include any filler other than carbon black. II-3 Vulcanization System

[0048] The vulcanization system is by definition sulfur-based. It may include molecular sulfur and / or at least one sulfur-donating agent. At least one vulcanization accelerator is also preferably present, and, optionally and also preferably, various known vulcanization activators such as zinc oxide, stearic acid or equivalent compounds such as stearic acid salts and transition metal salts, guanidine derivatives (in particular diphenylguanidine), or even known vulcanization retardants may be used.

[0049] Sulfur is used at a preferential rate of between 0.5 and 12 parts per annum, in particular between 1 and 10 parts per annum. The vulcanization accelerator is used at a preferential rate of between 0.5 and 10 parts per annum, more preferably between 0.5 and 5.0 parts per annum.

[0050] Any compound capable of acting as a vulcanization accelerator for diene elastomers in the presence of sulfur can be used as an accelerator, in particular accelerators of the thiazole type and their derivatives, accelerators of the sulfenamide, thiuram, dithiocarbamate, dithiophosphate, thiourea and xanthate types. Examples of such accelerators include the following compounds: 2-mercaptobenzothiazyl disulfide (abbreviated "MBTS"), N-cyclohexyl-2-benzothiazyl sulfenamide ("CBS"), N,N-dicyclohexyl-2-benzothiazyl sulfenamide ("DCBS"), N-ter-butyl-2-benzothiazyl sulfenamide ("TBBS"), N-ter-butyl-2-benzothiazyl sulfenimide ("TBSI"), tetrabenzylthiuram disulfide ("TBZTD"), zinc dibenzyldithiocarbamate ("ZBEC") and mixtures of these compounds. II-4 Epoxy Resin

[0051] The composition according to the invention comprises between 1 and 30 parts per annum of epoxy resin. Epoxy resins are reinforcing resins (or hardening resins) known to those skilled in the art for stiffening rubber compositions.

[0052] Epoxy resins usable in the present invention include all the Polyepoxide compounds. For example, the epoxy resin can be chosen from aromatic epoxy resins, alicyclic epoxy resins, and aliphatic epoxy resins. For example, the aromatic epoxy resin can be an amine-aromatic epoxy resin. These resins are preferably novolac epoxy resins, that is, epoxy resins obtained by acid catalysis, as opposed to resol resins, obtained by basic catalysis.

[0053] In particular, among aromatic epoxide compounds, epoxide resins chosen from the group consisting of 2,2 bis[4-(glycidyloxy)phenyl]propane, poly[o-cresylglycidyl ether)-co-formaldehyde], poly[phenylglycidyl ether)-co-formaldehyde], poly[(phenylglycidyl ether)-co(hydroxybenzaldehyde glycidyl ether)] and mixtures of these compounds are preferred.

[0054] Preferably, the epoxy resin is chosen from the group consisting of poly[o-cresylglycidyl ether)-co-formaldehyde], poly[o-phenylglycidyl ether)-co-formaldehyde], aromatic amine epoxy resins and mixtures of these compounds.

[0055] By way of example of commercially available epoxy resins that can be used within the framework of the present invention, one may cite, for example, the "DEN 439" epoxy resin from the company Uniqema, the epoxy resin “Tris(4-hydroxyphenyl)methane triglycidyl ether” from Sigma-Aldrich, the epoxy cresol novolac araldite ECN 1299 resin from Huntsman.

[0056] The quantity of epoxy resin is between 1 and 30 parts per cubic centimeter (ppm). Given the amine hardener used in the present invention, below the minimum resin content indicated, the intended technical effect is insufficient, while above the maximum indicated, there is a risk of excessive increase in rigidity and excessive penalization of hysteresis and Mooney plasticity. For all these reasons, the epoxy resin content is between 5 and 25 ppm. Preferably, the epoxy resin content in the composition according to the invention is between 10 and 20 ppm. II-5 Amino Hardener

[0057] The epoxy resin of the composition of the invention is associated with a particular amine hardener which allows the crosslinking of the resin.

[0058] According to the invention, the amine hardener comprises at least two primary amine functions located on at least (i.e., one or more) a six-atom aromatic ring, said at least one six-atom aromatic ring comprising: ° at least one primary amine function, and ° at least two Ri radicals, identical or different, chosen from the group consisting of linear or branched Ci-C6 alkyl radicals, halogens, and ethers, tertiary amines, thioethers, ketones, esters and amides, substituted by linear or branched Ci-C6 alkyl radicals, such that at least one six-atom aromatic ring does not contain a hydrogen atom located in an ortho position relative to the primary amine functions, said amine hardener comprising at least one second primary amine function located on said at least one six-atom aromatic ring or on a possible second six-atom aromatic ring of said amine hardener.

[0059] In other words, the amine hardener comprises one or more six-atom aromatic rings and at least two primary amine functions located on one or distributed over several of these six-atom aromatic rings.

[0060] As is well known to those skilled in the art, a primary amine function is understood to be an amine function in which the nitrogen atom is bonded to two hydrogen atoms.

[0061] Preferably, the amine hardener comprises 1 to 3, preferably also 1 or 2 aromatic rings of six atoms.

[0062] Preferably, the amine hardener comprises 2 to 4, preferably 2 more primary amine functions located on at least one six-atom aromatic ring of the amine hardener.

[0063] Among the halogens that can constitute the Ri radicals, we can mention fluorine, chlorine, bromine, or iodine atoms. Preferably, the halogens are chosen from the group consisting of chlorine and bromine atoms; even more preferably, the halogens are chlorine atoms.

[0064] According to a first embodiment of the present invention, the amine hardener may comprise a six-atom aromatic ring comprising: ° at least two primary amine functions, and ° at least two Ri radicals, identical or different, chosen from the group consisting of linear or branched Ci-C6 alkyl radicals, halogens, and ethers, tertiary amines, thioethers, ketones, esters and amides, substituted by linear or branched Ci-C6 alkyl radicals, so that said ring does not include a hydrogen atom located in an ortho position with respect to the primary amine functions.

[0065] According to a second embodiment of the present invention, the amine hardener may also comprise at least two identical or different six-atom aromatic rings, said rings each comprising: ° at least one primary amine function, and ° at least two Ri radicals, identical or different, chosen from the group consisting of linear or branched Ci-C6 alkyl radicals, halogens, and ethers, tertiary amines, thioethers, ketones, esters and amides, substituted by linear or branched Ci-C6 alkyl radicals, such that said rings do not include a hydrogen atom located in an ortho position relative to the primary amine functions.

[0066] According to another embodiment, the amine hardener can also comprise several six-atom aromatic rings and at least two primary amine functions located only on one of the aromatic rings.

[0067] When the amine hardener comprises several (i.e., at least two) six-atom aromatic rings, these rings may be identical or different. They may, for example, differ from one another in the nature of the atoms constituting said rings and / or in the number of primary amine functions located on said rings and / or in the nature and / or number of Ri radicals arranged on said rings and / or in the position of the primary amine functions and Ri radicals on said rings. Preferably, when the amine hardener comprises several six-atom aromatic rings, these rings are identical.

[0068] As indicated above, the amine hardener comprises at least two Ri radicals, identical or different, selected from the group consisting of linear or branched Ci-C6 alkyl radicals, halogens, and ethers, tertiary amines, thioethers, ketones, esters and amides, substituted by linear or branched Ci-C6 alkyl radicals. In the expression "ethers, tertiary amines, thioethers, ketones, esters and amides, substituted by linear or branched Ci-C6 alkyl radicals", the person skilled in the art understands that the terms "substituted by linear or branched Ci-C6 alkyl radicals" refer to each of the ethers, tertiary amines, thioethers, ketones, esters and amides.

[0069] Regardless of the embodiment of the present invention, the amine hardener preferably comprises at least two identical or different Ri radicals selected from the group consisting of linear or branched Ci-C6 alkyl radicals, halogens, and ethers, tertiary amines, and thioethers, substituted by linear or branched Ci-C6 alkyl radicals. Even more preferably, the amine hardener comprises at least two identical or different Ri radicals selected from the group consisting of linear or branched Ci-C6 alkyl radicals, halogens, and thioethers substituted by linear or branched Ci-C6 alkyl radicals.

[0070] Regardless of the embodiment of the present invention, the Ri radicals, whether identical or different, are preferably chosen from the group consisting of linear or branched Ci-C6 alkyl radicals. In other words, all the Ri radicals of the amine hardener can be linear or branched Ci-C6 alkyl radicals, the linear or branched Ci-C6 alkyl radicals being preferably chosen from the group consisting of methyl, ethyl and propyl radicals.

[0071] Regardless of the embodiment of the present invention, at least one cycle six-atom aromatic of the amine hardener may comprise at least two Ri radicals, identical or different, selected from the group consisting of halogens, and ethers, tertiary amines and thio-ethers, substituted by linear or branched Ci-C6 alkyl radicals, and at least one Ri radical selected from the group consisting of linear or branched Ci-C6 alkyl radicals.

[0072] Regardless of the embodiment of the present invention, whether dealing with Ri radicals or radicals of ethers, tertiary amines, thioethers, ketones, esters, or amides, the linear or branched Ci-C6 alkyl radicals may be selected from the group consisting of methyl, ethyl, propyl, isopropyl, isobutyl, and butyl radicals. Preferably, the linear or branched Ci-C6 alkyl radicals are selected from the group consisting of methyl, ethyl, and propyl radicals. Even more preferably, the linear or branched Ci-C6 alkyl radicals are selected from the group consisting of methyl and ethyl radicals.

[0073] Regardless of the embodiment of the present invention, the atoms of the aromatic rings of the amine hardener may be carbon atoms, and optionally include nitrogen atoms. Preferably, all the atoms of the aromatic rings of the amine hardener are carbon atoms. In other words, the six-atom aromatic rings of the amine hardener are preferably aromatic rings with six carbon atoms.

[0074] In formulas (III) to (VII) presented below, it is recalled that the radicals Ri can be identical or different.

[0075] According to the first embodiment of the present invention, the amine hardener can conform to formula (III): (NH2)2

[0076] Preferably, according to this embodiment, the amine hardener corresponds to formula (IV):

[0077] According to the second embodiment of the present invention, the amine hardener can also conform to the formula (V): in which n represents an integer from 0 to 4, preferably from 1 to 3, Ri and R2, identical or different, are chosen from the group consisting of a hydrogen atom and a methyl, ethyl, isobutyl or benzyl group, preferably Ri and R2 both represent a hydrogen atom.

[0078] Preferably, according to this embodiment, the amine hardener corresponds to formula (VI): in which n represents 1 or 2, preferably 1, Ri and R2, identical or different, are chosen from the group consisting of a hydrogen atom, a methyl, ethyl, isobutyl or benzyl group, preferably Ri and R2 both represent a hydrogen atom.

[0079] Preferably, according to this embodiment, the amine hardener corresponds to formula (VII):

[0080] Most preferably, according to the invention, the group constituted by the compounds of mixtures of these compounds: C2h5, CaHs (VIII), H2N.......})............nh2 -AV>—-- / 7 C2H5 C2H5 i, the amine hardener is chosen from items (VIII) to (XIII) below and the CaHs .Cl Cl C2H5 (IX), HZN—V CH2—<( '>—NH2 y—A A___ / / C2h( c2hs

[0081] As an example of commercially available amino hardeners that can be used in the context of the present invention, one can cite for example the "Ethacure 100" or the "Ethacure 300" from the company Albemarle, the "Lonzacure DETDA", the "Lonzacure MDEA" or the "Lonzacure MCDEA" from the company Lonza.

[0082] The quantity of amine hardener is between 1 and 15 parts per 10 ... II-6 Possible Additions

[0083] The rubber compositions according to the invention may optionally also include all or part of the usual additives commonly used in elastomer compositions for tires, such as plasticizers (such as plasticizing oils and / or plasticizing resins), reinforcing or non-reinforcing fillers other than those mentioned above, pigments, protective agents such as anti-ozone waxes, chemical anti-ozonants, antioxidants, anti-fatigue agents.

[0084] Advantageously, the composition according to the invention includes a condensation accelerator, which is particularly interesting for reducing the cooking time of the composition.

[0085] Thus, the composition according to the invention advantageously comprises an imidazole of general formula (XIV): Rd Jv (XIV) in which, - Ra represents a hydrogen atom or a hydrocarbon group, possibly interrupted by one or more heteroatoms and / or substituted, - Rb represents a hydrocarbon group, - Rc and Rd represent, independently of each other, a hydrogen atom or a hydrocarbon group, possibly interrupted by one or more heteroatoms and / or substituted, - or Rc and Rd together with the carbon atoms of the imidazole ring to which they are attached, form a ring possibly interrupted by one or more heteroatoms and / or substituted.

[0086] The expression "possibly interrupted by one or more heteroatoms and / or substituted" means that the Ra, Rc, and Rd groups can, independently and when they represent a hydrocarbon group, be interrupted by a heteroatom (that is, in other words, that a heteroatom is intercalated in the hydrocarbon chain), preferably chosen from nitrogen, oxygen, and sulfur, and / or substituted by a functional group. A functional group is understood to be a group comprising a heteroatom, preferably chosen from amino, alkylamine, alkoxyl, and hydroxyl groups.

[0087] By amino group, we mean a group of formula -NH2. By hydroxyl group, we mean a group of formula -OH.

[0088] Preferably, the hnidazole of general formula (XIV) has groups such as: - Ra is chosen from the group consisting of a hydrogen atom, alkyl groups having from 1 to 20 carbon atoms, cycloalkyls having from 5 to 24 carbon atoms, aryls having from 6 to 30 carbon atoms, aralkyls having from 7 to 25 carbon atoms, possibly substituted, - Rb is chosen from the group consisting of alkyl groups having from 1 to 20 carbon atoms, cycloalkyls having from 5 to 24 carbon atoms, aryls having from 6 to 30 carbon atoms or aralkyls having from 7 to 25 carbon atoms, - Rc and Rd are independently chosen from the group consisting of a hydrogen atom, alkyl groups having from 1 to 20 carbon atoms, cycloalkyls having from 5 to 24 carbon atoms, aryls having from 6 to 30 carbon atoms or aralkyls having from 7 to 25 carbon atoms; possibly substituted, or Rc and Rd together with the carbon atoms of the imidazole ring to which they are attached form a ring chosen from aromatic, heteroaromatic or aliphatic rings, comprising from 5 to 12 carbon atoms, preferably 5 or 6 carbon atoms.

[0089] Preferably, Ra is chosen from the group consisting of the alkyl groups having 2 to 12 carbon atoms and aralkyls having 7 to 13 carbon atoms, possibly substituted. More preferably, Ra is chosen from the group consisting of aralkyl groups having 7 to 13 carbon atoms, possibly substituted, and Rb is chosen from the group consisting of alkyl groups having 1 to 12 carbon atoms. Even more preferably, Ra is chosen from the group consisting of aralkyl groups having 7 to 11 carbon atoms, possibly substituted, and Rb is chosen from the group consisting of alkyl groups having 1 to 4 carbon atoms.

[0090] Preferably, Rc and Rd are independently selected from the group consisting of a hydrogen atom and alkyl groups having from 1 to 12 carbon atoms, cycloalkyls having from 5 to 8 carbon atoms, aryls having from 6 to 24 carbon atoms, and aralkyls having from 7 to 13 carbon atoms. Alternatively, and also preferably, Rc and Rd form, with the carbon atoms of the imidazole ring to which they are attached, a phenyl, cyclohexene, or cyclopentene ring.

[0091] Most preferably, Rc and Rd represent the hydrogen atom, Ra and Rb being chosen as described above.

[0092] In a preferred arrangement, Ra is a naphthylalkyl group comprising 11 to 13 carbon atoms, optionally substituted by at least one hydroxyl group, Rb is an alkyl group having 1 to 4 carbon atoms, and Rc and Rd are independently selected from the group consisting of one hydrogen atom and alkyl groups having 1 to 12 carbon atoms. A naphthylalkyl group is understood to be a group of general formula (XV), where n represents an integer from 1 to 3:

[0093] Preferably, Ra is a naphthylalkyl group comprising 11 to 13 carbon atoms substituted by at least one hydroxyl group, Rb is an alkyl group having 1 to 3 carbon atoms, and Rc and Rd are hydrogen atoms. Most preferably, Ra is a 2-naphthol-1-methyl group, Rb is a methyl group, and Rc and Rd are hydrogen atoms, with compound (XIV) then having the formula (XVI):

[0094] The rubber composition according to the invention preferably comprises 0.1 at 5 parts per 100% of imidazole of general formula (XIV). Below this minimum content, the technical effect is not significant, while above this content, imidazole of general formula (XIV) could compete with the amine hardener and alter the network obtained during crosslinking. Preferably, the composition comprises 0.1 to 3 parts per 100%, preferably 0.2 to 3 parts per 100%, preferably 0.2 to 2 parts per 100% of imidazole of general formula (XIV).

[0095] The imidazoles usable within the framework of the invention are either commercially available or easily prepared by those skilled in the art according to well-known techniques such as described for example in documents JP2012211122, JP2007269658 or in Science of Synthesis 2002,12, 325-528.

[0096] For example, as examples of commercially available imidazoles useful for the purposes of the invention, one can cite 1,2-dimethylimidazole, l-decyl-2-methylimidazole, l-benzyl-2-methylimidazole or l-((2-Methyl-lH-Imidazol-l-yl)Methyl)Naphthalen-2-ol commercially available under the name "Aradur 3123" from Huntsman.

[0097] 11-7 Preparation of rubber compositions

[0098] The compositions according to the invention can be manufactured in suitable mixers, using two successive preparation phases well known to those skilled in the art: - a first thermomechanical working or mixing phase (the so-called "non-productive" phase), which can be carried out in a single thermomechanical step during which all the necessary constituents, including the elastomeric matrix, the reinforcing filler, the epoxy resin, and any other miscellaneous additives, are introduced into a suitable mixer such as a standard internal mixer (for example, a "Banbury" type mixer). These include the elastomer matrix, the reinforcing filler, the epoxy resin, and any other miscellaneous additives, with the exception of the vulcanizing system, the amine hardener, and any condensation accelerator. The incorporation of any filler into the elastomer can be carried out in one or more stages by thermomechanical mixing.In cases where the filler is already incorporated, in whole or in part, into the elastomer in the form of a masterbatch, as described, for example, in applications WO 97 / 36724 or WO 99 / 16600, the masterbatch is directly mixed, and where applicable, other elastomers or fillers present in the composition that are not in masterbatch form, as well as any other miscellaneous additives other than the vulcanization system, are incorporated. The non-productive phase can be carried out at high temperature, up to a maximum temperature between 110°C and 200°C, preferably between 130°C and 185°C, for a duration generally between 2 and 10 minutes. - a second phase of mechanical work (the so-called "productive" phase), which can be carried out in an external mixer such as a roller mixer, after cooling the mixture obtained during the first non-productive phase to a lower temperature, typically below 120°C, for example between 40°C and 100°C. The vulcanization system is then incorporated, and the whole is then mixed for a few minutes, for example between 5 and 15 min.

[0099] Such phases have been described for example in applications EP-A-0501227, EP-A-0735088, EP-A-0810258, WO00 / 05300 or WO00 / 05301.

[0100] The final composition thus obtained is then calendered, for example, into a sheet or plate, particularly for laboratory characterization, or extruded (or co-extruded with another rubber composition) into a semi-finished (or profile) rubber product usable, for example, as an inner layer of a tire. These products can then be used for the manufacture of tires, according to techniques known to those skilled in the art.

[0101] The composition can be either in the raw state (before crosslinking or vulcanization), or in the cooked state (after crosslinking or vulcanization), can be a semi-finished product that can be used in a tire.

[0102] The crosslinking of the composition can be carried out in a manner known to those skilled in the art, for example at a temperature between 130°C and 200°C, under pressure. II-8 Rubber Article

[0103] The present invention also relates to a rubber article comprising at least one composition according to the invention. Preferably, the rubber article is a tire.

[0104] More particularly, the invention also relates to a pneumatic or non-pneumatic tire having at least one inner layer comprising a composition according to the invention. The composition according to the invention may constitute part or all of the inner layer of the tire. The inner layer is preferably selected from the group consisting of carcass plies, crown plies, bead packs, crown pads, decoupling layers, edge rubbers, packing rubbers, tread sublayer, and combinations of these inner layers. More preferably, the inner layer is selected from the group consisting of bead packs, crown pads, tread sublayer, and combinations of these inner layers. More preferably still, the inner layer is selected from the group consisting of bead packs, crown pads, and combinations of these inner layers.

[0105] The tire according to the invention can be intended to equip any type of vehicle, in particular motor vehicles, without any particular limitation. III- PREFERRED EMBODIMENTS

[0106] In view of the foregoing, the preferred embodiments of the invention are described below:

[0107] 1. Rubber composition based on at least: - an elastomeric matrix comprising more than 50 parts per cent of at least one copolymer containing ethylene units and 1,3-diene units, the ethylene units in the copolymer representing between 50% and 95% by mole of the monomer units of the copolymer, - a reinforcing load, - a vulcanization system, - from 1 to 30 pieces of epoxy resin, - between 1 and 15 parts of an amine hardener comprising at least two primary amine functions, located on at least one six-atom aromatic ring, said at least one six-atom aromatic ring comprising: ° at least one primary amine function, and ° at least two Ri radicals, identical or different, chosen from the group consisting of linear or branched Ci-C6 alkyl radicals, halogens, ethers, tertiary amines, thioethers, ketones, esters and amides, substituted by linear or branched Ci-C6 alkyl radicals, such that at least one six-atom aromatic ring does not contain a hydrogen atom located in an ortho position relative to the primary amine functions, said amine hardener comprising at least one second primary amine function located on said at least one six-atom aromatic ring or on a possible second six-atom aromatic ring of said amine hardener. 2. Rubber composition according to embodiment 1, in which the ethylene units in the copolymer represent between 55% and 90% by mole of the monomer units of the copolymer. 3. Rubber composition according to any one of the preceding embodiments, wherein the copolymer containing ethylene units and 1,3-diene units is a copolymer of ethylene and 1,3-diene. 4. Rubber composition according to any one of the preceding embodiments, wherein the 1,3-diene is 1,3-butadiene. 5. Rubber composition according to any one of the preceding embodiments, wherein the copolymer contains units of formula (I) or units of formula (II) or units of formula (I) and formula (II): -CH2-CH(CH=CH2)- (II) 6. Rubber composition according to any one embodiment 5, in which the molar percentages of formula units (1) and formula units (2) in the copolymer, respectively o and p, satisfy the following equation (eq. 1), preferably to equation (eq. 2), o and p being calculated on the basis of all monomer units of the copolymer. 0 < o+p < 25 (eq. 1) 0 < o+p < 20 (eq. 2) 7. Rubber composition according to any one of the preceding embodiments, wherein the copolymer containing ethylene units and 1,3-diene units is a statistical copolymer. 8. Rubber composition according to any one of the preceding embodiments, wherein the proportion of the copolymer containing ethylene units and 1,3-diene units is in the range of 60 to 100 parts per annum, preferably 80 to 100 parts per annum. 9. Rubber composition according to any one of the preceding embodiments, wherein the epoxy resin is selected from aromatic epoxy resins, alicyclic epoxy resins and aliphatic epoxy resins. 10. Rubber composition according to any one of embodiments 1 to 8, wherein the epoxy resin is selected from the group consisting of 2,2 bis[4-(glycidyloxy)phenyl]propane, poly[o-cresylglycidyl ether)-co-formaldehyde], poly[phenylglycidyl ether)-co-formaldehyde], poly[(phenylglycidyl ether)-co(hydroxybenzaldehyde glycidyl ether)] and mixtures of these compounds. 11. Rubber composition according to any one of the preceding embodiments, wherein the epoxy resin content is between 5 and 25 parts per annum, preferably between 10 and 20 parts per annum. 12. Rubber composition according to any one of the preceding embodiments, wherein the Ri radicals, identical or different, are selected from the group consisting of linear or branched Ci-C6 alkyl radicals, halogens, ethers, tertiary amines and thio-ethers, substituted by linear or branched Ci-C6 alkyl radicals. 13. Rubber composition according to any one of the preceding embodiments, in which the Ri radicals, identical or different, are chosen from the group consisting of linear or branched Ci-C6 alkyl radicals. 14. Rubber composition according to any one of embodiments 1 to 12, wherein at least one six-atom aromatic ring of the amine hardener comprises at least two Ri radicals, identical or different, selected from the group consisting of halogens, and ethers, tertiary amines and thioethers, substituted by linear or branched Ci-C6 alkyl radicals, and at least one Ri radical selected from the group consisting of linear or branched Ci-C6 alkyl radicals. 15. Rubber composition according to any one of the preceding embodiments, wherein the linear or branched Ci-C6 alkyl radicals are selected from the group consisting of the methyl, ethyl, propyl, isopropyl, isobutyl and butyl radicals, preferably from the group consisting of the methyl and ethyl radicals. 16. Rubber composition according to any one of the preceding embodiments, wherein at least one six-atom aromatic ring is a six-carbon aromatic ring. 17. Rubber composition according to any one of the preceding embodiments, in which the amine hardener corresponds to formula (III): (¾. (HI) (iw2 18. Rubber composition according to any one of embodiments 1 to 16, in which the amine hardener corresponds to formula (IV): Ri (IV) 19. Rubber composition according to any one of embodiments 1 to 16, in which the amine hardener corresponds to formula (V): in which n represents an integer from 0 to 4, preferably from 1 to 3, Ri and R2, identical or different, are chosen from the group consisting of a hydrogen atom and a methyl, ethyl, isobutyl or benzyl group, preferably Ri and R2 both represent a hydrogen atom. 20. Rubber composition according to any one of embodiments 1 to 16 or 19, in which the amine hardener corresponds to formula (VI): in which n represents 1 or 2, preferably 1, Ri and R2, identical or different, are chosen from the group consisting of a hydrogen atom, a methyl, ethyl, isobutyl or benzyl group, preferably Ri and R2 both represent a hydrogen atom. 21. Rubber composition according to any one of embodiments 1 to 16, in which the amine hardener corresponds to formula (VII): 22. Rubber composition according to any one of embodiments 1 to 16, wherein the amine hardener is selected from the group consisting of the compounds of formulas (VIII) to (XIII) below and mixtures of these compounds: nh2 23. Rubber composition according to any of the preceding embodiments, wherein the amount of amine hardener is in the range of 5 to 10 parts per annum, preferably 2 to 8 parts per annum. 24. Rubber composition according to any one of the preceding embodiments, further comprising an imidazole of formula (XIV): (XIV) X / R-""" N in which, ° Ra represents a hydrogen atom or a hydrocarbon group, possibly interrupted by one or more heteroatoms and / or substituted, ° Rb represents a hydrocarbon group, ° Rc and Rd represent, independently of each other, a hydrogen atom or a hydrocarbon group, possibly interrupted by one or more heteroatoms and / or substituted, ° or Rc and Rd together with the carbon atoms of the imidazole ring to which they are attached, form a ring possibly interrupted by one or more heteroatoms and / or substituted. 25. Rubber composition according to embodiment 24, wherein the imidazole of formula (XIV) contains: - Ra is chosen from the group consisting of a hydrogen atom, alkyl groups having from 1 to 20 carbon atoms, cycloalkyls having from 5 to 24 carbon atoms, aryls having from 6 to 30 carbon atoms, aralkyls having from 7 to 25 carbon atoms, possibly substituted, - Rb is chosen from the group consisting of alkyl groups having from 1 to 20 carbon atoms, cycloalkyls having from 5 to 24 carbon atoms, aryls having from 6 to 30 carbon atoms or aralkyls having from 7 to 25 carbon atoms, - Rc and Rd are independently chosen from the group consisting of a hydrogen atom, alkyl groups having from 1 to 20 carbon atoms, cycloalkyls having from 5 to 24 carbon atoms, aryls having from 6 to 30 carbon atoms or aralkyls having from 7 to 25 carbon atoms, possibly substituted, or Rc and Rd together with the carbon atoms of the imidazole ring to which they are attached, form a ring chosen from among the aromatic, heteroaromatic or aliphatic rings, comprising from 5 to 12 carbon atoms, preferably 5 or 6 carbon atoms. 26. Rubber composition according to any one of embodiments 24 to 25, wherein, in the imidazole of formula (XIV), Ra is selected from the group consisting of alkyl groups having from 2 to 12 carbon atoms and aralkyl groups having from 7 to 13 carbon atoms, optionally substituted. 27. Rubber composition according to any one of embodiments 24 to 26, wherein, in the imidazole of formula (XIV), Ra is selected from the group consisting of aralkyl groups having 7 to 13 optionally substituted carbon atoms and Rb is selected from the group consisting of alkyl groups having 1 to 12 carbon atoms. 28. Rubber composition according to any one of embodiments 24 to 27, wherein, in the imidazole of formula (XIV), Ra is selected from the group consisting of aralkyl groups having 7 to 11 optionally substituted carbon atoms and Rb is selected from the group consisting of alkyl groups having 1 to 4 carbon atoms. 29. Rubber composition according to any one of embodiments 24 to 28, wherein, in the imidazole of formula (XIV), Rc and Rd are independently selected from the group consisting of a hydrogen atom and the alkyl groups having from 1 to 12 carbon atoms, cycloalkyls having from 5 to 8 carbon atoms, aryls having from 6 to 24 carbon atoms and aralkyls having from 7 to 13 carbon atoms, Rc and Rd being very preferentially the hydrogen atom. 30. Rubber composition according to any one of embodiments 24 to 28, wherein, in the imidazole of formula (XIV), Rc and Rd form with the carbon atoms of the imidazole ring to which they are attached, a phenyl, cyclohexene, or cyclopentene ring. 31. Rubber composition according to embodiment 24, wherein, in the imidazole of formula (XIV), Ra is a naphthylalkyl group comprising from 11 to 13 carbon atoms, optionally substituted by at least one hydroxyl group, Rb is an alkyl group having from 1 to 4 carbon atoms, Rc and Rd are independently selected from the group consisting of one hydrogen atom and the alkyl groups having from 1 to 12 carbon atoms. 32. Rubber composition according to embodiment 31, wherein Ra is a naphthylalkyl group comprising 11 to 13 carbon atoms substituted by at least one hydroxyl group, Rb is an alkyl group having 1 to 3 carbon atoms, Rc and Rd are hydrogen atoms, and wherein Ra is preferably a group 2-naphtholmethyl, Rb is a methyl group, Rc and Rd are the hydrogen atom, the compound (XIV) then corresponds to the formula (XVI):

[0108] 33. Rubber composition according to any one of embodiments 24 to 32, wherein the proportion of imidazole of formula (XIV) is in the range of 0.1 to 5 pc, preferably 0.1 to 3 pc. 34. Rubber composition according to any one of the preceding embodiments, wherein the reinforcing filler comprises carbon black, silica or a mixture thereof. 35. Rubber composition according to any of the preceding embodiments, wherein the reinforcing filler comprises more than 50% by weight, preferably more than 80% by weight, of carbon black. 36. Rubber composition according to any one of embodiments 34 to 35, wherein the carbon black has a specific surface area BET in the range of 100 to 160 m2 / g, preferably 124 to 150 m2 / g. 37. Rubber composition according to any of the preceding embodiments, wherein the rate of reinforcing filler is in the range of 10 to less than 100 parts per annum, preferably from 15 to 90 parts per annum. 38. Rubber article comprising a composition as defined in any one of embodiments 1 to 37. 39. Pneumatics comprising a composition as defined in any one of embodiments 1 to 37. 40. Tire according to embodiment 39, in which the composition defined in any one of embodiments 1 to 37 is present in at least one inner layer, preferably chosen from the group consisting of carcass plies, crown plies, bead-fillers, crown feet, decoupling layers, edge rubbers, filling rubbers, tread sublayer and combinations of these inner layers. IV- EXAMPLES IV-1 Measurements and tests used Mechanical properties These tensile tests allow us to determine the elastic stresses and the Tensile strength properties. Processing the tensile recordings also allows for plotting the modulus curve as a function of elongation. The modulus used here is the nominal (or apparent) secant modulus measured at the first elongation, calculated by referring back to the initial cross-section of the specimen. Tensile stresses (CR in MPa) and elongations at break (AR in %) are measured at 23°C ± 2°C, according to standard NF T 46-002 of September 1988. The tensile energy is equal to the product of the elongation at break and the tensile stress.

[0109] The elongation-at-break results are expressed as a percentage, base 100, relative to the control composition T1 or T2, as applicable. A result greater than 100 indicates an improvement in the mechanical properties of the composition considered.

[0110] The dynamic properties G* and tan(ô)max are measured on a viscoanalyzer (Metravib VA4000), according to ASTM D5992-96. The response of a vulcanized composition sample (cylindrical specimen 2 mm thick and 79 mm2 cross-section) is recorded, subjected to sinusoidal loading in alternating simple shear, at a frequency of 10 Hz, at 60°C according to ASTM D 1349-09. A strain amplitude sweep is performed from 0.01% to 50% (forward cycle), then from 50% to 0.01% (reverse cycle).

[0111] The results used are the complex dynamic shear modulus G* and the loss factor tan(ô)max. On the forward cycle, the value of G* at 5% strain and the loss factor, denoted tan(ô)max, are recorded.

[0112] The results of G* at 60°C with 5% strain on the forward cycle and of tan(φ)max at 60°C on the forward cycle are expressed as performance base 100, the value 100 being assigned to the control T1 or T2 as appropriate. A result greater than 100 indicates that the composition of the example considered is respectively more rigid and less hysteretic, reflecting respectively better rigidity for the application considered and lower hysteresis.

[0113] Determination of the microstructure of elastomers by nuclear magnetic resonance (NMR):

[0114] The microstructure of ethylene and butadiene copolymers is determined by 1H NMR analysis, supplemented by 13C NMR analysis when the resolution of the 1H NMR spectra does not allow for the assignment and quantification of all species. The measurements are performed using a BRUKER 500 MHz NMR spectrometer at frequencies of 500.43 MHz for proton observation and 125.83 MHz for carbon observation. For insoluble elastomers that swell in a solvent, a 4 mm z-grad HRMAS probe is used, allowing observation of the proton and carbon in proton-decoupled mode. The spectra are acquired at rotation speeds of 4000 Hz to 5000 Hz. For measurements on soluble elastomers, a liquid NMR probe is used, allowing observation of the Proton and carbon are decoupled from the proton. Insoluble samples are prepared in rotors filled with the material being analyzed and a deuterated solvent that induces swelling, generally deuterated chloroform (CDC13). The solvent used must always be deuterated, and its chemical composition can be adapted by those skilled in the art. The quantities of material used are adjusted to obtain spectra with sufficient sensitivity and resolution. Soluble samples are dissolved in a deuterated solvent (approximately 25 mg of elastomer in µL), generally deuterated chloroform (CDC13). The solvent or solvent cutoff used must always be deuterated, and its chemical composition can be adapted by those skilled in the art. In both cases (soluble sample or swollen sample): For proton NMR, a single 30° pulse sequence is used.The spectral window is adjusted to observe all resonance lines belonging to the analyzed molecules. The number of accumulations is set to obtain a signal-to-noise ratio sufficient for quantifying each motif. The recycle time between each pulse is adjusted to obtain a quantitative measurement. For carbon NMR, a simple 30° pulse sequence is used with proton decoupling only during acquisition to avoid Nuclear Overhauser (NOE) effects and maintain quantitative accuracy. The spectral window is adjusted to observe all resonance lines belonging to the analyzed molecules. The number of accumulations is set to obtain a signal-to-noise ratio sufficient for quantifying each motif. The recycle time between each pulse is adjusted to obtain a quantitative measurement. NMR measurements are performed at 25°C.

[0115] Determination of the macrostructure of polymers by size exclusion chromatography (SEC):

[0116] Size exclusion chromatography (SEC) allows the fractionation of polymer chains in a solvent according to their hydrodynamic volume. Like any chromatographic system, the technique is based on the elution of a solute (the polymer) through a column containing a stationary phase. The system consists, in this order, of a solvent reservoir, a pumping system, an injector, a set of columns, and detectors. The measurement chain is equipped with a Waters Alliance e2695 module and a Waters fRI410 refractometer.

[0117] The mobile phase is eluted at a flow rate of 1 mL / min. The polymer is solubilized in THF in the presence of 1 wt% diisopropylamine and 1 wt% triethylamine at a concentration of 1 g / L. A volume of 100 pL is injected through a set of three A GELENT (MIXED B LS) size-exclusion chromatography columns. The columns are temperature-controlled in an oven at 35°C. The stationary phase of the columns is based on a divinylbenzene polystyrene gel with controlled porosity. The polymer chains are separated according to their hydrodynamic volume. These particles occupy space when solubilized in the solvent. The larger the volume they occupy, the less accessible the column pores are to them, and the shorter their elution time. Detection is performed using a refractometer (RI) thermostated at 35°C. Each elution volume is associated with a mass via Moore calibration (certified standard: Polymer Standard Service (Mainz) standard polystyrenes). The WATERS: EMPOWER software is used for data acquisition and analysis. It is then possible to determine the number-average molar masses (Mn), the mass-average molar masses (Mw), and the polydispersity (Ip = Mw / Mn). Mooney ML 1+4

[0118] For polymers and rubber compositions, the Mooney viscosities ML(l+4) at 100°C are measured using an oscillating consistometer according to ASTM D-1646 (1999). The Mooney plasticity measurement is performed according to the following principle: the composition in its raw state (i.e., before curing) is molded in a cylindrical chamber heated to 100°C. After one minute of preheating, the rotor rotates within the specimen at 2 revolutions per minute, and the torque required to maintain this rotation after 4 minutes of rotation is measured. The Mooney plasticity ML(l+4) is expressed in "Mooney units" (MU, with 1 MU = 0.83 Nm). IV-2 Synthesis of the El copolymer:

[0119] In the polymer synthesis, all reagents are commercially available except for the metallocenes. BOMAG butylmagnesium (20% in heptane, C = 0.88 mol.L*) is sourced from Chemtura and is stored in a Schlenk tube under an inert atmosphere. The N35 grade ethylene is sourced from Air Liquide and is used without prior purification.

[0120] The ethylene and 1,3-butadiene copolymer: El elastomer (according to the invention) is synthesized according to the procedure described below.

[0121] In a reactor containing methylcyclohexane, ethylene (Et), and butadiene (Bd) at 80°C in the proportions indicated in Table 1, butylmagnesium (BOMAG) is added to neutralize impurities in the reactor, followed by the catalytic system (see Table 1). At this point, the reaction temperature is regulated to 80°C and the polymerization reaction begins. The polymerization reaction proceeds at a constant pressure of 8 bar. The reactor is fed with ethylene and butadiene (Bd) throughout the polymerization process in the proportions defined in Table 1. The polymerization reaction is stopped by cooling, degassing the reactor, and adding ethanol. An antioxidant is added to the polymer solution. The copolymer is recovered by drying in a vacuum oven to a constant mass. The catalytic system is a preformed catalytic system. It is prepared in the methyl- cyclohexane from a metallocene, [Me2SiFlu2Nd(p-BH4)2Li(THF)], a cocatalyst, butylloctylmagnesium (BOMAG), and a preforming monomer, 1,3-butadiene, in the amounts indicated in Table 1. It is prepared according to a preparation method in accordance with paragraph II.1 of patent application WO 2017 / 093654 Al.

[0122] The microstructure of the El copolymer and its properties are shown in Tables 2 and 3. For the microstructure, Table 2 shows the molar ratios of the ethylene (Eth) units, the 1,3-butadiene units, and the 1,2-cyclohexanediyl (ring) motifs.

[0123] [Tables 1] Synthesis El Metallocene concentration (mmol / L) 0.07 Alkylating agent concentration (mmol / L) 0.36 Preform monomer / metal molar ratio Nd 90 Feed composition (%mol Et / Bd) 80 / 20

[0124] [Tables2] El Ethylene elastomer (%mol) 77 Butadiene 1,3 (%mol) 15 1,2-cyclohexanediyl (%mol) 8

[0125] [Tables3] Elastomer El Tg (°C) -40 Mn (g / mol) 177,000 Mooney (ML (1+4)) at 100°C 80 IV-3 Preparation of compositions

[0126] In the following examples, the rubbery compositions were produced as described in section 11-7 above. In particular, the "non-productive" phase was carried out in a 0.4-liter mixer for 3.5 minutes, at an average paddle speed of 50 revolutions per minute, until a maximum drop temperature of 165°C was reached. The "productive" phase was carried out in a roller tool at 40°C for 5 minutes.

[0127] The crosslinking of the composition was carried out at a temperature between 130°C and 200°C, under pressure. IV-4 Tests of Rubber Compositions

[0128] The examples presented below are intended to compare the performance trade-off between stiffness, hysteresis and mechanical properties (elongation at break and tensile strength) of a composition according to the present invention (Cl) with three control compositions (Tl to T3).

[0129] Table 4 presents the compositions tested (in pieces), as well as the results obtained.

[0130] Composition Cl differs from the control composition Tl only in the nature of the butadiene-styrene-based copolymer. Control compositions T2 and T3 allow for the study of the impact of the absence of the epoxy resin-based curing system and amine hardener.

[0131] The results of the Cl composition are expressed as a percentage based on 100 relative to the control composition T1 and the results of the T3 composition are expressed as a percentage based on 100 relative to the control composition T2.

[0132] [Tables4] Compositions Tl Cl T2 T3 NR(1) 100 - 100 - Elastomer El(2) - 100 - 100 NI 15(3) 60 60 60 60 Hardening resin(4) 19.5 19.5 - - Hardener(5) 4.4 4.4 - - 6PPD(6) 2.0 2.0 2.0 2.0 Stearic acid(7) 1.0 1.0 1.0 1.0 ZnO(8) 2.7 2.7 2.7 2.7 Sulfur 5.0 5.0 5.0 5.0 Accelerator(9) 2.0 2.0 - - CBS(10) 0.9 0.9 0.9 0.9 Properties AR at 23°C 100 100 ND* ND* CR at 23°C 100 110 ND* ND* G* 5% at 60°C 100 145 100 152 tan(θ)max at 60°C 100 113 100 83

[0133] (1) Natural rubber (2) Elastomer obtained by the process described in point IV-2 above (3) NI 15 grade carbon black according to ASTM D-1765 (4) "Araldite ECN 1299 CH" epoxy thermosetting resin from Huntsman (5) Huntsman company “Ethacure 300” amino hardener (6) Nl,3-dimethylbutyl-N-phenylparaphenylenediamine “Santaflex 6-PPD” from Flexsys (7) Stearic acid “Pristerene 4931” from the company Uniqema (8) Industrial grade zinc oxide from Umicore (9) Imidazole accelerator “Aradur 3123ES” from Huntsman Company (10) N-cyclohexyl-2-benzothiazyl sulfenamide “Santicure CBS” from Flexsys * Not available

[0134] The results presented in Table 4 above show that the combination of a copolymer according to the invention and a curing system based on epoxy resin and an amine hardener according to the invention improves both the stiffness and hysteresis of the composition without compromising the mechanical properties, and even improves them. Comparison of the control compositions T2 and T3 shows that this effect is not solely due to the presence of the copolymer according to the invention. The compositions according to the invention are particularly useful for applications requiring an excellent stiffness / hysteresis compromise, such as in tires, especially in the inner layers of tires.

Claims

Claims

1. Rubber composition based on at least: - an elastomer matrix comprising more than 50 phr of at least one copolymer containing ethylene units and 1,3-diene units, the ethylene units in the copolymer representing between 50% and 95% by mole of the monomer units of the copolymer, - - a reinforcing filler, - a vulcanization system, - from 1 to 30 phr of epoxy resin, - between 1 and 15 phr of an amine hardener comprising at least two primary amine functions, located on at least one aromatic ring with six atoms, said at least one aromatic ring with six atoms comprising: • at least one primary amine function, and • at least two radicals Ri, identical or different, chosen from the group consisting of linear or branched alkyl radicals C1-C6, halogens, ethers, tertiary amines, thioethers, ketones, esters and amides,substituted by linear or branched C1-C6 alkyl radicals, such that the at least one six-atom aromatic ring does not comprise a hydrogen atom located in the ortho position relative to the primary amine functions, said amine hardener comprising at least one second primary amine function located on said at least one six-atom aromatic ring or on a possible second six-atom aromatic ring of said amine hardener.,

2. A rubber composition according to claim 1, wherein the copolymer containing ethylene units and 1,3-diene units is a copolymer of ethylene and 1,3-diene, the 1,3-diene preferably being 1,3-butadiene.

3. A rubber composition according to any preceding claim, wherein the level of the copolymer containing units ethylene and 1,3-diene units is within a range of 60 to 100 phr, preferably 80 to 100 phr.

4. A rubber composition according to any preceding claim, wherein the epoxy resin is selected from aromatic epoxy resins, alicyclic epoxy resins and aliphatic epoxy resins, preferably the epoxy resin is selected from the group consisting of 2,2 bis[4-(glycidyloxy)phenyl]propane, poly[o-cresylglycidyl ether)-co-formaldehyde], poly[phenylglycidyl ether)-co-formaldehyde], poly[(phenylglycidyl ether)-co(hydroxybenzaldehyde glycidyl ether)] and mixtures of these compounds.

5. Rubber composition according to any one of the preceding claims, in which the epoxy resin content is between 5 and 25 phr, preferably between 10 and 20 phr.

6. Rubber composition according to any one of the preceding claims, in which the radicals Ri, identical or different, are chosen from the group consisting of linear or branched C1-C6 alkyl radicals, halogens, ethers, tertiary amines and thioethers, substituted by linear or branched C1-C6 alkyl radicals, preferably the radicals Ri, identical or different, are chosen from the group consisting of linear or branched C1-C6 alkyl radicals.

7. A rubber composition according to any preceding claim, wherein the at least one six-membered aromatic ring is a six-carbon aromatic ring.

8. A rubber composition according to any preceding claim, wherein the amine hardener corresponds to any one of formulae (III) to (V) and (VII): <in)’ (NH2)2 in which, in formula (V):

9. - n represents an integer ranging from 0 to 4, preferably from 1 to 3, - Ri and R2, identical or different, are chosen from the group consisting of a hydrogen atom and a methyl, ethyl, isobutyl or benzyl group, preferably Ri and R2 both represent a hydrogen atom. A rubber composition according to any one of claims 1 to 7, wherein the amine hardener is selected from the group consisting of compounds of formulae (VIII) to (XIII) below and mixtures of these compounds: c2h5 caHs (VIII) H2N............<■' .......NH2 v— C?HS 'CaHs

10.

11. Rubber composition according to any one of the preceding claims, in which the level of amine hardener is in a range from 5 to 10 phr, preferably from 2 to 8 phr. A rubber composition according to any preceding claim, further comprising an imidazole of formula (XIV): (XIV) ---N / / \ ..■•X: R^" X "X b in which, • Ra represents a hydrogen atom or a hydrocarbon group, optionally interrupted by one or more heteroatoms and / or substituted, • Rb represents a hydrocarbon group, • Rc and Rd represent, independently of each other, a hydrogen atom or a hydrocarbon group, optionally interrupted by one or more heteroatoms and / or substituted, • or Rc and Rd form together with the carbon atoms of the imidazole ring to which they are attached, a ring possibly interrupted by one or more heteroatoms and / or substituted.

12.

13.

14. Rubber composition according to claim 11, in which the level of imidazole of formula (XIV) is within a range from 0.1 to 5 pce, preferably from 0.1 to 3 pce. A rubber composition according to any preceding claim, wherein the reinforcing filler comprises more than 50% by weight, preferably more than 80% by weight of carbon black. Rubber composition according to any one of the preceding claims, in which the level of the reinforcing filler is in a range from 10 to less than 100 phr, preferably from 15 to 90 pc.

15. A tire comprising a rubber composition as defined in any one of claims 1 to 14, wherein the composition is preferably present in at least one inner layer, preferably selected from the group consisting of carcass plies, crown plies, bead fillers, crown feet, decoupling layers, edge rubbers, filler rubbers, tread sub-layer and combinations of these inner layers.