RUBBER COMPOSITION

Description

[0001] The present invention relates to diene rubber compositions intended for use in a tire which predominantly contain as elastomer a copolymer of ethylene and 1,3-dienes.

[0002] Diene rubber compositions traditionally used in tires are rubber compositions reinforced with highly unsaturated diene elastomers such as polybutadienes, polyisoprenes, butadiene and styrene copolymers.

[0003] It has been proposed, in particular in document WO 2014114607, to use copolymers of ethylene and 1,3-butadiene in rubber compositions for tires. These copolymers, which contain more than 50 mol% of ethylene units, are referred to as highly saturated diene elastomers.

[0004] Rubber compositions comprising these highly saturated diene elastomers require relatively long residence times in a curing press to be vulcanized, which has the consequence of reducing the productivity of a production line for articles containing these rubber compositions, such as tires. Furthermore, these rubber compositions, once vulcanized, have a much higher stiffness than the diene rubber compositions traditionally used and may therefore prove unsuitable for certain applications. The level of stiffness of a rubber composition is defined in part by the degree of vulcanization of the rubber, which depends on both the vulcanization kinetics and the residence time of the rubber composition in the curing press.The solution which would simply consist of extracting the rubber composition from the curing press before the end of the vulcanization reaction is not satisfactory, because it would lead to an insufficiently cured rubber composition which would then be more hysteretic.

[0005] The Applicant has discovered a reinforced rubber composition based on a copolymer of ethylene and 1,3-dienes which makes it possible to resolve the difficulties encountered and which therefore has the advantage of presenting an improved compromise between the properties of rigidity, hysteresis and curing.

[0006] Thus, a first subject of the invention is a rubber composition which comprises a reinforcing filler, a vulcanization system and more than 50 to 100 pce of an elastomer which contains more than 50 mol% of ethylene units and which is a copolymer of ethylene, a first 1,3-diene which is 1,3-butadiene, isoprene or their mixture, and a second 1,3-diene of formula CH 2 =CR-CH=CH 2 , the symbol R representing an unsaturated aliphatic hydrocarbon chain having 3 to 20 carbon atoms.

[0007] Another subject of the invention is a tire which comprises a tread, which tire comprises a rubber composition in accordance with the invention, in particular in its tread. Description

[0008] Any interval of values ​​designated by the expression "between a and b" represents the domain of values ​​greater than "a" and less than "b" (i.e., excluding the limits 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 limits a and b).

[0009] The abbreviation "pce" means parts by weight per hundred parts of elastomer (of the total elastomers if more than one elastomer is present).

[0010] The compounds mentioned in the description may be of fossil or bio-sourced origin. 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.

[0011] In the present invention, the term "tyre" means a pneumatic or non-pneumatic tire. A pneumatic tire usually comprises two beads intended to come into contact with a rim, a crown composed of at least one crown reinforcement and a tread, two sidewalls, the tire being reinforced by a carcass reinforcement anchored in the two beads. A non-pneumatic tire, for its part, usually comprises a base, designed for example for mounting on a rigid rim, a crown reinforcement, ensuring the connection with a tread and a deformable structure, such as spokes, ribs or cells, this structure being arranged between the base and the crown. Such non-pneumatic tires do not necessarily comprise a sidewall. Non-pneumatic tires are described for example in documents WO 03 / 018332 and FR2898077.According to any one of the embodiments of the invention, the tire according to the invention is preferably a pneumatic bandage.

[0012] Unless otherwise indicated, the rates of units resulting from the insertion of a monomer into a copolymer such as the copolymer useful in the invention are expressed as a molar percentage relative to the total of the monomer units of the copolymer.

[0013] The elastomer useful for the purposes of the invention is a copolymer of ethylene, a first 1,3-diene and a second 1,3-diene.

[0014] The first 1,3-diene is 1,3-butadiene, isoprene or their mixture, i.e. a mixture of 1,3-butadiene and isoprene. The first 1,3-diene is preferably 1,3-butadiene.

[0015] The second 1,3-diene has the formula (I) in which the symbol R represents an unsaturated aliphatic hydrocarbon chain having 3 to 20 carbon atoms. CH 2 =CR-CH=CH 2 (I)

[0016] The second 1,3-diene is a single compound, i.e., a single (in English "one") 1,3-diene of formula (I) or is a mixture of 1,3-dienes of formula (I), the 1,3-dienes in the mixture differing from each other by the group represented by the symbol R.

[0017] Preferably, the chain represented by R contains 6 to 16 carbon atoms. It may be a straight or branched chain, in which case the symbol R represents a straight or branched chain. Preferably, the hydrocarbon chain is acyclic, in which case the symbol R represents an acyclic chain. More preferably, the symbol R represents an unsaturated and branched acyclic hydrocarbon chain. The hydrocarbon chain represented by the symbol R is advantageously an unsaturated and branched acyclic chain containing from 3 to 20 carbon atoms, in particular from 6 to 16 carbon atoms. Very advantageously, the 1,3-diene is myrcene, β-farnesene or a mixture of myrcene and β-farnesene.

[0018] According to a preferred embodiment of the invention, the 1,3-diene is myrcene.

[0019] According to another preferred embodiment of the invention, the 1,3-diene is β-farnesene.

[0020] Since the copolymer is a copolymer of ethylene, a first 1,3-diene and a second 1,3-diene, the monomer units of the copolymer are units resulting from the polymerization of ethylene, the first 1,3-diene and the second 1,3-diene. The copolymer therefore comprises ethylene units, units of the first 1,3-diene and units of the second 1,3-diene.

[0021] The second 1,3-diene being a substituted 1,3 diene, its polymerization can give rise to units of 1,2 configuration represented by formula (1), of 3,4 configuration represented by formula (2) and of 1,4 configuration whose trans form is represented below by formula (3).

[0022] As is well known, the first 1,3-diene can give rise to 1,3-diene units which are 1,2 or 3,4 configuration units as is the case for example with isoprene and 1,4 configuration units.

[0023] Also well known, the ethylene unit is a -(CH 2 -CH 2 )- unit.

[0024] The copolymer useful for the invention is advantageously a random copolymer according to any one of the embodiments of the invention. Very advantageously, the copolymer is an atactic polymer according to any one of the embodiments of the invention.

[0025] According to the invention, the copolymer contains more than 50 mol% of ethylene units. Preferably, the copolymer contains more than 60 mol% of ethylene units. More preferably, it contains at least 70 mol% of ethylene units. The copolymer preferably contains at most 85 mol% of ethylene units.

[0026] Preferably, the copolymer contains less than 30 mol% of units of the second 1,3-diene. More preferably, the copolymer contains at most 20 mol% of units of the second 1,3-diene. Even more preferably, the copolymer contains at most 15 mol% of units of the second 1,3-diene.

[0027] According to one embodiment, the copolymer contains less than 30 mol% of units of the first 1,3-diene.

[0028] According to another embodiment, the copolymer contains less than 20 mol% of units of the first 1,3-diene.

[0029] Preferably, the copolymer contains less than 20 mol% of units of the first 1,3-diene.

[0030] According to one embodiment of the invention, the copolymer contains more than 60% to 90% by mole of ethylene units and less than 30% by mole, preferably at most 20% by mole of units of the second 1,3-diene, more preferably at most 15% by mole of units of the second 1,3-diene. According to this embodiment of the invention, the copolymer preferably contains less than 30% by mole of units of the first 1,3-diene or preferably contains less than 20% by mole of units of the first 1,3-diene.

[0031] According to another embodiment of the invention, the copolymer contains from 70% to 90% by mole of ethylene units and less than 30% by mole, preferably at most 20% by mole of units of the second 1,3-diene, more preferably at most 15% by mole of units of the second 1,3-diene. According to this embodiment of the invention, the copolymer preferably contains less than 20% by mole of units of the first 1,3-diene.

[0032] According to yet another embodiment of the invention, the copolymer contains more than 60% to 85% by mole of ethylene units and less than 30% by mole, preferably at most 20% by mole, more preferably at most 15% by mole of units of the second 1,3-diene. According to this embodiment of the invention, the copolymer preferably contains less than 30% by mole of units of the first 1,3-diene or preferably contains less than 20% by mole of units of the first 1,3-diene.

[0033] According to yet another embodiment of the invention, the copolymer contains from 70% to 85% by mole of ethylene units and less than 30% by mole, preferably at most 20% by mole, more preferably at most 15% by mole of units of the second 1,3-diene. According to this embodiment of the invention, the copolymer preferably contains less than 20% by mole of units of the first 1,3-diene.

[0034] According to any one of the embodiments of the invention, the copolymer preferably contains less than 80 mol% of ethylene units.

[0035] According to any one of the embodiments of the invention, the copolymer preferably contains at least 1 mol% of units of the second 1,3-diene, more preferably at least 5 mol% of units of the second 1,3-diene.

[0036] According to a particular embodiment of the invention, in particular when the first 1,3-diene is 1,3-butadiene or a mixture of 1,3-butadiene and isoprene, the copolymer further contains 1,2-cyclohexanediyl units. The presence of these cyclic structures in the copolymer results from a very particular insertion of ethylene and 1,3-butadiene during the polymerization. The content of 1,2-cyclohexanediyl units in the copolymer varies according to the respective contents of ethylene and 1,3-butadiene in the copolymer. The copolymer preferably contains less than 15 mol% of 1,2-cyclohexanediyl unit units.

[0037] Preferably, the copolymer has a glass transition temperature below -35°C, preferably between -70°C and -35°C.

[0038] The copolymer may be prepared by a process which comprises the polymerization of a mixture of ethylene, the first 1,3-diene and the second 1,3-diene in the presence of a catalytic system based on at least one metallocene of formula (II) and an organomagnesium compound of formula (III) P(Cp 1< Cp 2< ) Nd(BH 4 ) (1+y)- L y N x (II) MgR 1< R 2< (III) Cp 1< and Cp 2< , identical or different, being chosen from the group consisting of the cyclopentadienyl group of formula C 5 H 4 , the unsubstituted fluorenyl group of formula C 13 H 8 and the substituted fluorenyl groups, P being a group bridging the two groups Cp 1< and Cp 2< and representing a group ZR 3< R 4< , Z representing a silicon or carbon atom, R 3< and R 4< , identical or different, each representing an alkyl group comprising from 1 to 20 carbon atoms, preferably a methyl, y, an integer, being equal to or greater than 0, x, an integer or not, being equal to or greater than 0, L representing an alkali metal chosen from the group consisting of lithium, sodium and potassium, N representing a molecule of an ether, preferably diethyl ether or tetrahydrofuran, R 1< and R 2< , identical or different, representing a carbon group.

[0039] Substituted fluorenyl groups include those substituted by alkyl radicals having 1 to 6 carbon atoms or by aryl radicals having 6 to 12 carbon atoms. The choice of radicals is also guided by the accessibility of the corresponding molecules, which are substituted fluorenes, because the latter are commercially available or easily synthesized.

[0040] As substituted fluorenyl groups, mention may be made more particularly of the 2,7-ditertiobutyl-fluorenyl and 3,6-ditertiobutyl-fluorenyl groups. Positions 2, 3, 6 and 7 respectively designate the position of the carbon atoms of the rings as shown in the diagram below, position 9 corresponding to the carbon atom to which the P bridge is attached.

[0041] The catalytic system can be prepared in a traditional manner by a process similar to that described in patent application WO 2007054224 or WO 2007054223. For example, the organomagnesium compound and the metallocene are reacted in a hydrocarbon solvent, typically at a temperature ranging from 20 to 80°C for a period of between 5 and 60 minutes. The catalytic system is generally prepared in a hydrocarbon solvent, aliphatic such as methylcyclohexane or aromatic such as toluene. Generally, after its synthesis, the catalytic system is used as is in the copolymer synthesis process.

[0042] Alternatively, the catalytic system may be prepared by a process analogous to that described in patent application WO 2017093654 A1 or in patent application WO 2018020122 A1. According to this alternative, the catalytic system further contains a preformation monomer chosen from a conjugated diene, ethylene or a mixture of ethylene and a conjugated diene, in which case the catalytic system is based at least on the metallocene, the organomagnesium compound and the preformation monomer. For example, the organomagnesium compound and the metallocene are reacted in a hydrocarbon solvent, typically at a temperature of 20 to 80°C for 10 to 20 minutes to obtain a first reaction product, then with this first reaction product, the preformation monomer chosen from a conjugated diene, ethylene or a mixture of ethylene and a conjugated diene is reacted at a temperature of 40 to 90°C for 1 hour to 12 hours.The catalytic system thus obtained can be used immediately in the process according to the invention or be stored under an inert atmosphere before its use in the polymerization process to prepare the copolymer.

[0043] The metallocene used to prepare the catalytic system may be in the form of a crystallized or non-crystalline powder, or in the form of single crystals. The metallocene may be in a monomeric or dimeric form, these forms depending on the method of preparation of the metallocene, as for example described in patent application WO 2007054224 or WO 2007054223. The metallocene may be prepared in a conventional manner by a process analogous to that described in patent application WO 2007054224 or WO 2007054223, in particular by reaction under inert and anhydrous conditions of the salt of an alkali metal of the ligand with a rare earth borohydride in a suitable solvent, such as an ether, such as diethyl ether or tetrahydrofuran or any other solvent known to those skilled in the art. After reaction, the metallocene is separated from the reaction by-products by techniques known to those skilled in the art, such as filtration or precipitation in a second solvent.The metallocene is finally dried and isolated in solid form.

[0044] Like any synthesis carried out in the presence of organometallic compounds, the synthesis of the metallocene and that of the catalytic system take place under anhydrous conditions under an inert atmosphere. Typically, the reactions are carried out from solvents and anhydrous compounds under anhydrous nitrogen or argon.

[0045] The organomagnesium compound used in the catalytic system has the formula MgR 1< R 2< in which R 1< and R 2< , which may be identical or different, represent a carbon group. A carbon group is understood to mean a group which contains one or more carbon atoms. Preferably, R 1< and R 2< contain 2 to 10 carbon atoms. More preferably, R 1< and R 2< each represent an alkyl. The organomagnesium compound is advantageously a dialkylmagnesium compound, better still butylethylmagnesium or butyloctylmagnesium, even better still butyloctylmagnesium.

[0046] The molar ratio of the organomagnesium to the Nd metal constituting the metallocene is preferably within a range from 1 to 100, more preferably is greater than or equal to 1 and less than 10. The range of values ​​from 1 to less than 10 is particularly more favorable for obtaining copolymers with high molar masses.

[0047] When the copolymer is a polymer which comprises 1,2-cyclohexanediyl units, it is prepared according to the process mentioned in the present application using a metallocene of formula (II) in which Cp 1< and Cp 2< , identical or different, are chosen from the group consisting of substituted fluorenyl groups and the unsubstituted fluorenyl group of formula C 13 H 8 . For this variant, the following metallocenes are particularly suitable in which the symbol Flu has the fluorenyl group of formula C 13 H 8 : [{Me 2 SiFlu 2 Nd(µ-BH 4 ) 2 Li(THF)} 2 ] ; [Me 2 SiFlu 2 Nd(µ-BH 4 ) 2 Li(THF)]; [Me 2 SiFlu 2 Nd(µ-BH 4 )(THF)] ; [{Me 2 SiFlu 2 Nd(µ-BH 4 )(THF)} 2 ]; [Me 2 SiFlu 2 Nd(µ-BH 4 )].

[0048] The skilled person also adapts the polymerization conditions and the concentrations of each of the reactants (components of the catalytic system, monomers) according to the equipment (tools, reactors) used to carry out the polymerization and the various chemical reactions. As is known to the skilled person, the polymerization as well as the handling of the monomers, the catalytic system and the polymerization solvent(s) are carried out under anhydrous conditions and under an inert atmosphere. The polymerization solvents are typically hydrocarbon, aliphatic or aromatic solvents.

[0049] The polymerization is preferably carried out in solution, continuously or batchwise. The polymerization solvent may be a hydrocarbon, aromatic or aliphatic solvent. Examples of polymerization solvents include toluene and methylcyclohexane. The monomers may be introduced into the reactor containing the polymerization solvent and the catalytic system or, conversely, the catalytic system may be introduced into the reactor containing the polymerization solvent and the monomers. The copolymerization is typically carried out under anhydrous conditions and in the absence of oxygen, in the optional presence of an inert gas. The polymerization temperature generally varies within a range from 30 to 150°C, preferably from 30 to 120°C. Preferably, the copolymerization is carried out at constant ethylene pressure.

[0050] During the polymerization of ethylene and 1,3-dienes in a polymerization reactor, a continuous addition of ethylene and 1,3-dienes may be carried out into the polymerization reactor, in which case the polymerization reactor is a fed reactor. This embodiment is particularly suitable for the synthesis of random copolymer.

[0051] The polymerization can be stopped by cooling the polymerization medium or by adding an alcohol. The polymer can be recovered using conventional techniques known to those skilled in the art, such as precipitation, evaporation of the solvent under reduced pressure or stripping with water vapor.

[0052] Alternatively, instead of adding an alcohol, a functionalizing agent can be added, in which case a polymer carrying a function such as an amine function, a silanol function or an alkoxysilane function is recovered. According to a particular embodiment of the invention, the copolymer carries an amine, alkoxysilane or silanol function.

[0053] According to a first variant in which the function carried by the polymer is an amine function, the functionalizing agent is preferably a compound of formula (IV), Si(Fc 1< ) 3-g (Rc 2< ) g (Rca) (IV) the symbols Fc 1< , identical or different, representing an alkoxy group, the symbols Rc 2< , identical or different, representing a hydrogen atom or a hydrocarbon chain, the symbol Rca representing a hydrocarbon chain substituted by an amine function, g being an integer ranging from 0 to 1.

[0054] The alkoxy group represented by the symbol Fc 1< in formula (IV) is preferably methoxy or ethoxy.

[0055] The amine function designated in the symbol Rca in formula (IV), namely the amine function of the functionalizing agent, is a protected primary amine function, a protected secondary amine function or a tertiary amine function. As protecting groups for the primary and secondary amine functions, mention may be made of silyl groups, for example trimethylsilyl and tert-butyldimethylsilyl groups. Preferably, the amine function of the functionalizing agent is a tertiary amine function. Advantageously, the amine function of the functionalizing agent is a tertiary amine function of formula -N(RB ) 2 in which each RB represents an alkyl, preferably a methyl or an ethyl.

[0056] As functionalizing agent for preparing a polymer bearing an amine function according to the first variant, mention may be made of the compounds (N,N-dimethyl-3-aminopropyl)methyldimethoxysilane, (N,N-dimethyl-3-aminopropyl)methyldiethoxysilane, (N,N-dimethyl-3-aminopropyl)ethyldimethoxysilane, (N,N-dimethyl-3-aminopropyl)ethyl-diethoxysilane, (N,N-dimethylaminopropyl)trimethoxysilane, (N,N-dimethylaminopropyl)triethoxysilane and (N-(3-trimethoxysilyl)propyl)-N-(trimethylsilyl)silanamine, (N-(3-triethoxysilyl)propyl)-N-(trimethylsilyl)silanamine, preferably (N,N-dimethyl-3-aminopropyl)methyldimethoxysilane, (N,N-dimethyl-3-aminopropyl)ethyldimethoxysilane, (N,N-dimethylaminopropyl)trimethoxysilane and (N-(3-trimethoxysilyl)-propyl)-N-(trimethylsilyl)silanamine, more preferably (N,N-dimethylaminopropyl)trimethoxysilane and (N-(3-trimethoxysilyl)propyl)-N-(trimethylsilyl)-silanamine.

[0057] According to a second variant in which the function carried by the polymer is a silanol or alkoxysilane function, the functionalizing agent is preferably a compound of formula (V), Si(Fc 1< ) 4-g (Rc 2< ) g (V) the symbols Fc 1< , identical or different, representing an alkoxy group or a halogen atom, the symbols Rc 2< , identical or different, representing a hydrogen atom, a hydrocarbon chain or a hydrocarbon chain substituted by a chemical function Fc 2< , g being an integer ranging from 0 to 2.

[0058] When the symbol Fc 1< represents an alkoxy group in formula (V), the alkoxy group is preferably methoxy or ethoxy. When the symbol Fc 1< represents a halogen atom in formula (V), the halogen atom is preferably chlorine.

[0059] Among the hydrocarbon chains represented by the symbols Rc 2< in formulas (V), mention may be made of alkyls, preferably alkyls having at most 6 carbon atoms, more preferably methyl or ethyl, better still methyl.

[0060] Among the hydrocarbon chains substituted by a chemical function Fc 2< which are represented by the symbols Rc 2< in the formulas (V), mention may be made of alkanediyl chains, preferably those comprising at most 6 carbon atoms, more preferably the 1,3-propanediyl group, the alkanediyl group carrying a substituent, the chemical function Fc 2< , in other words, one valence of the alkanediyl chain for the function Fc 2< , the other valence for the silicon atom of the methoxysilane function.

[0061] In formulas (V), chemical function is understood to mean a group which is different from a saturated hydrocarbon group and which can participate in chemical reactions. A person skilled in the art understands that the chemical function Fc 2< in formula (V) is a group which is chemically inert with respect to the chemical species present in the polymerization medium. The chemical function Fc 2< in formula (V) may be in a protected form, as for example in the case of the primary amine, secondary amine or thiol function. As chemical function Fc 2< , the following may be mentioned: ether, thioether, protected primary amine, protected secondary amine, tertiary amine, protected thiol, silyl functions. Preferably, the chemical function Fc 2< in formula (V) is a protected primary amine function, a protected secondary amine function, a tertiary amine function or a protected thiol function.As protecting groups for primary amine, secondary amine and thiol functions, mention may be made of silyl groups, for example trimethylsilyl and tert-butyldimethylsilyl groups.

[0062] As functionalizing agent for preparing a polymer carrying a silanol or alkoxysilane function according to the second variant, mention may be made of the compounds dimethoxydimethylsilane, diethoxydimethylsilane, dimethoxydiethylsilane, diethoxydiethylsilane, (N,N-dimethyl-3-aminopropyl)methyldimethoxysilane, (N,N-dimethyl-3-aminopropyl)methyldiethoxysilane, (N,N-dimethyl-3-aminopropyl)ethyldimethoxysilane, (N,N-dimethyl-3-aminopropyl)ethyl-diethoxysilane, 3-methoxy-3,8,8,9,9-pentamethyl-2-oxa-7-thia-3,8-disiladecane, trimethoxy-methylsilane, triethoxymethylsilane, trimethoxyethylsilane, triethoxyethylsilane, (N,N-dimethylaminopropyl)trimethoxysilane, (N,N-dimethylaminopropyl)triethoxysilane, (N-(3-trimethoxysilyl)propyl)-N-(trimethylsilyl)silanamine, (N-(3-triethoxysilyl)propyl)-N-(trimethylsilyl)silanamine and 3,3-dimethoxy-8,8,9,9-tetramethyl-2-oxa-7-thia-3,8-disiladecane, preferably dimethoxydimethylsilane, dimethoxydiethylsilane, (N,N-dimethyl-3-aminopropyl)methyldimethoxysilane, (N,N-dimethyl-3-aminopropyl)ethyldimethoxysilane, 3-methoxy-3,8,8,9,9-pentamethyl-2-oxa-7-thia-3,8-disiladecanetrimethoxymethylsilane, trimethoxyethylsilane, (N,N-dimethylaminopropyl)trimethoxysilane, (N-(3-trimethoxysilyl)-propyl)-N-(trimethylsilyl)silanamine and 3,3-dimethoxy-8,8,9,9-tetramethyl-2-oxa-7-thia-3,8-disiladecane, more preferably trimethoxymethylsilane, trimethoxyethylsilane, (N,N-dimethylaminopropyl)trimethoxysilane, (N-(3-trimethoxysilyl)propyl)-N-(trimethylsilyl)-silanamine and 3,3-dimethoxy-8,8,9,9-tetramethyl-2-oxa-7-thia-3,8-disiladecane.,

[0063] Whether it is the first or second variant, the functionalizing agent is typically added to the polymerization medium. It is typically added to the polymerization medium at a monomer conversion rate chosen by a person skilled in the art according to the desired macrostructure of the copolymer. Since the polymerization step is generally carried out under ethylene pressure, degassing of the polymerization reactor may be carried out before adding the functionalizing agent. The functionalizing agent is added under inert and anhydrous conditions to the polymerization medium, maintained at the polymerization temperature. 0.25 to 10 moles of functionalizing agent are typically used per 1 mole of co-catalyst, preferably 2 to 4 moles of functionalizing agent per 1 mole of co-catalyst.The functionalizing agent is brought into contact with the polymerization medium for a sufficient time to allow the functionalization reaction. This contact time is judiciously chosen by a person skilled in the art depending on the concentration of the reaction medium and the temperature of the reaction medium. Typically, the functionalization reaction is carried out with stirring, at a temperature ranging from 17 to 80°C, for 0.01 to 24 hours.

[0064] When the functionalizing agent carries a protected function as described above, the polymer functionalization step can be followed by a hydrolysis reaction to form a copolymer carrying a deprotected function, such as a primary amine, a secondary amine or a thiol function.

[0065] A hydrolysis reaction can also follow the polymer functionalization reaction when the functionalization reaction leads to the formation of a polymer bearing an alkoxysilane function. The hydrolysis of the polymer bearing an alkoxysilane function leads to the preparation of a polymer bearing a silanol function.

[0066] The rubber composition according to the invention comprises more than 50 to 100 phr of a copolymer of ethylene, a first 1,3-diene and a second 1,3-diene, copolymer as defined in any of the embodiments described above, including their variants. It is understood that the copolymer of ethylene, a first 1,3-diene and a second 1,3-diene may consist of a mixture of copolymers of ethylene, a first 1,3-diene and a second 1,3-diene which differ from each other by their microstructure or by their macrostructure. When the content of the copolymer is greater than 50 phr and less than 100 phr, the balance to 100 phr may be provided by another elastomer, in particular another diene elastomer known to those skilled in the art.This other diene elastomer may be an elastomer conventionally used in tire rubber compositions such as polybutadienes, polyisoprenes, 1,3-butadiene copolymers and isoprene copolymers. According to a preferred embodiment, the rubber composition comprises 100 phr of a copolymer of ethylene, a first 1,3-diene and a second 1,3-diene, copolymer as defined in any of the embodiments described above, including variants thereof.

[0067] The rubber composition according to the invention has the other essential characteristic of comprising a reinforcing filler. The rubber composition may comprise any type of so-called reinforcing filler, known for its ability to reinforce a rubber composition usable for the manufacture of tires, for example an organic filler such as carbon black, a reinforcing inorganic filler such as silica with which a coupling agent is associated in a known manner, or a mixture of these two types of filler. Such a reinforcing filler typically consists of nanoparticles whose average size (by mass) is less than one micrometer, generally less than 500 nm, most often between 20 and 200 nm, in particular and more preferably between 20 and 150 nm.

[0068] The level of reinforcing filler is adjusted by a person skilled in the art depending on the use of the rubber composition. According to one embodiment of the invention, the level of reinforcing filler in the rubber composition is greater than or equal to 30 phr and less than or equal to 200 phr, preferably greater than or equal to 35 phr and less than or equal to 100 phr.

[0069] The reinforcing filler may be a silica, a carbon black, or a mixture of a carbon black and a silica. Preferably, the reinforcing filler comprises a silica that represents more than 50% by mass of the reinforcing filler. More preferably, the silica represents more than 85% by mass of the reinforcing filler.

[0070] The silica used may be any reinforcing silica known to those skilled in the art, in particular any precipitated or pyrogenic silica having a BET specific surface area and a CTAB specific surface area both less than 450 m 2 < / g, preferably within a range from 30 to 400 m 2 < / g, in particular from 60 to 300 m 2 < / g. In this presentation, the BET specific surface area is determined by gas adsorption using the Brunauer-Emmett-Teller method described in "The Journal of the American Chemical Society" (Vol. 60, page 309, February 1938), and more precisely according to a method adapted from the NF ISO 5794-1 standard, annex E of June 2010 [multipoint volumetric method (5 points) - gas: nitrogen - vacuum degassing: one hour at 160°C - relative pressure range p / po: 0.05 to 0.17].

[0071] The CTAB specific surface area values ​​were determined according to standard NF ISO 5794-1, annex G of June 2010. The process is based on the adsorption of CTAB (N-hexadecyl-N,N,N-trimethylammonium bromide) on the “external” surface of the reinforcing filler.

[0072] Any type of precipitated silica may be used, in particular highly dispersible precipitated silicas (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, we can notably use the silicas “Ultrasil ®< 5000GR”, “Ultrasil ®< 7000GR” from the company Evonik, the silicas “Zeosil ®< 1085GR”, “Zeosil ®< 1115 MP”, “Zeosil ®< 1165MP”, “Zeosil ®< Premium 200MP”, “Zeosil ®< HRS 1200 MP” from the company Solvay.As non-HDS silica, the following commercial silicas can be used: silicas “Ultrasil ®< VN2GR”, “Ultrasil ®< VN3GR” from Evonik, silica “Zeosil ®< 175GR” from Solvay, silicas “Hi-Sil EZ120G(-D)”, “Hi-Sil EZ160G(-D)”, “Hi-Sil EZ200G(-D)”, “Hi-Sil 243LD”, “Hi-Sil 210”, “Hi-Sil HDP 320G” from PPG.

[0073] The silica may be a mixture of different silicas, in which case the proportions of silica in the reinforcing filler relate to all the silicas.

[0074] Suitable carbon blacks are all carbon blacks, including those conventionally used in tires or their treads. Among the latter, we will particularly mention the reinforcing carbon blacks of the 100, 200, 300 series, or the blacks of the 500, 600 or 700 series (ASTM D-1765-2017 grades), such as for example blacks N115, N134, N234, N326, N330, N339, N347, N375, N550, N683, N772. These carbon blacks can be used in the isolated state, as commercially available, or in any other form, for example as a carrier for some of the rubber additives used.

[0075] Carbon black can be a mixture of different carbon blacks, in which case the carbon black ratios refer to all carbon blacks.

[0076] According to any of the embodiments of the invention, the carbon black is preferably used at a rate less than or equal to 20 phr, more preferably less than or equal to 10 phr (for example, the carbon black rate may be within a range from 0.5 to 20 phr, in particular from 1 to 10 phr). Advantageously, the carbon black rate in the rubber composition is less than or equal to 5 phr. In the indicated ranges, the coloring (black pigmenting agent) and anti-UV properties of carbon blacks are benefited from, without otherwise penalizing the typical performances provided by silica.

[0077] To couple the reinforcing inorganic filler, in this case silica, to the elastomer, it is possible to use, in a well-known manner, an at least bifunctional coupling agent (or bonding agent) intended to ensure a sufficient connection, of a chemical and / or physical nature, between the inorganic filler (surface of its particles) and the elastomer, in which case the rubber composition comprises a coupling agent for bonding the silica to the elastomer. In particular, at least bifunctional organosilanes or polyorganosiloxanes are used. By "bifunctional", we mean a compound having a first functional group capable of interacting with the inorganic filler and a second functional group capable of interacting with the elastomer.

[0078] In particular, polysulfurized silanes, called "symmetrical" or "asymmetrical" depending on their particular structure, are used, as described for example in applications WO03 / 002648-A1 (or US2005 / 016651-A1) and WO03 / 002649-A1 (or US2005 / 016650-A1). In particular, polysulfurized silanes corresponding to the following general formula (IV) are suitable, without the following definition being limiting, in which: ZAS x -AZ (IV) x is an integer from 2 to 8 (preferably from 2 to 5); the symbols A, identical or different, represent a divalent hydrocarbon radical (preferably a C 1 -C 18 alkylene group or a C 6 -C 12 arylene group, more particularly a C 1 -C 10 alkylene, in particular a C 1 -C 4 alkylene, in particular propylene); the symbols Z, identical or different, correspond to one of the three formulas below: in which: the radicals R a< , substituted or unsubstituted, identical or different from each other, represent a C 1 -C 18 alkyl group, a C 3 -C 18 cycloalkyl group or a C 6 -C 18 aryl group (preferably C 1 -C 6 alkyl groups, cyclohexyl or phenyl, in particular C 1 -C 4 alkyl groups, more particularly methyl and / or ethyl), the radicals R b< , substituted or unsubstituted, identical or different from each other, represent a C 1 -C 18 alkoxyl group or a C 3 -C 18 cycloalkoxyl group (preferably a group chosen from C 1 -C 8 alkoxyls and C 5 -C 8 cycloalkoxyls, more preferably still a group chosen from C 1 -C 4 , in particular methoxyl and ethoxyl), or a hydroxyl group, or such that 2 Rb radicals represent a C 3 -C 18 dialkoxyl group.

[0079] In the case of a mixture of polysulfurized alkoxysilanes corresponding to formula (V) above, in particular usual commercially available mixtures, the average value of the “x” is a fractional number preferably within a range from 2 to 5, more preferably close to 4.

[0080] Examples of polysulfurized silanes include polysulfides (especially disulfides, trisulfides or tetrasulfides) of bis-(alkoxyl(C 1 -C 4 )-alkyl(C 1 -C 4 )silyl-alkyl(C 1 -C 4 )), such as, for example, polysulfides of bis(3-trimethoxysilylpropyl) or bis(3-triethoxysilylpropyl). Among these compounds, bis(3-triethoxysilylpropyl) tetrasulfide, abbreviated TESPT, of formula [(C 2 H 3 O) 3 Si(CH 2 ) 3 S 2 ] 2 marketed under the name “Si69” by the company Evonik, or bis-(triethoxysilylpropyl) disulfide, abbreviated TESPD, of formula [(C 2 H 3 O) 3 Si(CH 2 ) 3 S] 2 marketed under the name “Si75” by the company Evonik, is used in particular.Mention will also be made, as preferred examples, of polysulfides (in particular disulfides, trisulfides or tetrasulfides) of bis-(monoalkoxyl(C 1 -C 4 )-dialkyl(C 1 -C 4 )silylpropyl), more particularly bis-monoethoxydimethylsilylpropyl tetrasulfide as described in the aforementioned patent application WO02 / 083782-A1 (or US7217751-B2).

[0081] Of course, mixtures of the coupling agents described above could also be used.

[0082] The content of coupling agent in the composition of the invention is advantageously less than or equal to 25 phr, it being understood that it is generally desirable to use as little as possible. Typically the level of coupling agent represents from 0.5% to 15% by weight relative to the amount of reinforcing inorganic filler. Its level is preferably within a range from 0.5 to 20 phr, more preferably within a range from 3 to 15 phr. This level is easily adjusted by a person skilled in the art according to the level of reinforcing inorganic filler used in the composition of the invention.

[0083] The crosslinking system useful for the purposes of the invention is a vulcanization system, i.e. based on sulfur and a vulcanization accelerator. The sulfur is typically provided in the form of molecular sulfur or a sulfur donor agent, preferably in molecular form. Sulfur in molecular form is also referred to as molecular sulfur. A sulfur donor is understood to mean any compound that releases sulfur atoms, combined or not in the form of a polysulfide chain, capable of being inserted into the polysulfide chains formed during vulcanization and bridging the elastomer chains. Various known vulcanization activators such as zinc oxide, stearic acid, guanidine derivatives (in particular diphenylguanidine), etc., may be added to the vulcanization system, incorporated during the first non-productive phase and / or during the productive phase.The sulfur content is preferably between 0.5 and 3.0 pce, that of the accelerator is preferably between 0.5 and 5.0 pce. These preferential rates can apply to any of the embodiments of the invention.

[0084] Any compound capable of acting as a vulcanization accelerator (primary or secondary) may be used which is capable of acting as a vulcanization accelerator for diene elastomers in the presence of sulfur, in particular accelerators of the thiazole type and their derivatives, accelerators of the sulfenamide type for primary accelerators, and accelerators of the thiuram, dithiocarbamate, dithiophosphate, thiourea and xanthate type for secondary accelerators.

[0085] Vulcanization is carried out in a known manner at a temperature generally between 130°C and 200°C.

[0086] The rubber composition according to the invention may also contain other additives known to be used in rubber compositions for tires, such as plasticizers such as hydrocarbon oils or resins, antiozonants, antioxidants.

[0087] Suitable oils include non-aromatic or low-aromatic oils, e.g. aliphatic oils, paraffinic oils, MES oils, TDAE oils, TRAE oils, SRAE oils, mineral oils and their mixtures.

[0088] Hydrocarbon resins, also called hydrocarbon plasticizing resins, are polymers well known to those skilled in the art, essentially based on carbon and hydrogen but which may contain other types of atoms, for example oxygen, which can be used in particular as plasticizing agents or tackifying agents in polymer matrices. They are by nature at least partially miscible (i.e., compatible) at the rates used with the polymer compositions for which they are intended, so as to act as true diluting agents. They have been described for example in the work entitled "Hydrocarbon Resins" by R. Mildenberg, M. Zander and G. Collin (New York, VCH, 1997, ISBN 3-527-28617-9) of which chapter 5 is devoted to their applications, in particular in pneumatic rubber (5.5. "Rubber Tires and Mechanical Goods").As is known, these hydrocarbon resins can also be described as thermoplastic resins in the sense that they soften upon heating and can thus be molded.

[0089] According to a particular embodiment of the invention, the rubber composition comprises a plasticizing hydrocarbon resin. This embodiment is preferred when the rubber composition is used in a tire tread.

[0090] The level of plasticizer in the rubber composition is adjusted by a person skilled in the art according to the nature of the plasticizer depending on the level of reinforcing filler and the use for which the rubber composition is intended.

[0091] The rubber composition in accordance with the invention is typically manufactured in suitable mixers, using two successive preparation phases well known to those skilled in the art: a first thermomechanical working or kneading phase (so-called "non-productive" phase) at high temperature, up to a maximum temperature of between 130°C and 200°C, followed by a second mechanical working phase (so-called "productive" phase) down to a lower temperature, typically below 110°C, for example between 40°C and 100°C, finishing phase during which the crosslinking system is incorporated.

[0092] The rubber composition in accordance with the invention, which may be either in the raw state (before crosslinking or vulcanization), or in the cooked state (after crosslinking or vulcanization), may be used in a semi-finished article for a tire, preferably in a tire tread.

[0093] Another subject of the invention, the tire which comprises a tread, comprises a rubber composition in accordance with the invention defined under any one of the embodiments of the invention, preferably in its tread.

[0094] The above-mentioned characteristics of the present invention, as well as others, will be better understood upon reading the following description of several exemplary embodiments of the invention, given for illustrative and non-limiting purposes. Examples I-Characterization of polymers : I-1) Determination of the microstructure of polymers: a) Determination of the microstructure of Ethylene-Butadiene-Myrcene copolymers:

[0095] Spectral characterization and microstructure measurements of Ethylene-Butadiene-Myrcene copolymer are performed by Nuclear Magnetic Resonance (NMR) spectroscopy.

[0096] For these measurements, a Bruker Avance III HD 400 MHz spectrometer is used, equipped with a Bruker cryo-BBFO z-grad 5 mm probe. 1H experiments are recorded using a radiofrequency pulse with a flip angle of 30°, the number of repetitions is 128 with a recycle delay of 5 seconds. 1H-13C correlation NMR experiments HSQC (Heteronuclear Single Quantum Coherence) and HMBC (Heteronuclear Multiple-Bond Correlation) are recorded with a number of repetitions of 128 and a number of increments of 128. The experiments are carried out at 25 °C.

[0097] 25 mg of sample are solubilized in 1 mL of deuterated orthodichlorobenzene (ODCB).

[0098] The 1H and 13C chemical shift axes are calibrated relative to the protonated solvent impurity at δ1H = 7.2 ppm (for the most deshielded signal) and δ13C = 127 ppm (for the least deshielded signal).

[0099] Possible monomeric units in the copolymer are -CH 2 -CH(CH=CH 2 )-, -CH 2 -CH=CH-CH 2 -, -CH 2 -CH 2 -, the 1,2-cyclohexanediyl unit and the following structures, with R 1 and R 2 representing the polymer chain:

[0100] The 1,2-cyclohexanediyl unit has the following structure:

[0101] The signals of the insertion forms of myrcene A were observed on the different recorded spectra. According to S. Georges et al. (S.Georges, M.Bria, P. Zinck and M. Visseaux. Polymer 55 (2014) 3869-3878), the signal of the -CH= group n°8" characteristic of the C form presents chemical shifts 1< H and 13< C identical to the -CH= group n°3.

[0102] The chemical shifts of the characteristic signals of the polymer are presented in Table 1 (Assignment of the 1< H and 13< C signals of the Ethylene-Butadiene-Myrcene copolymers other than those of the 1,3-butadiene units). Table 1 δ 1< H (ppm) δ 13< C (ppm) Group 5.19 125.1 3 + 8" 4.86 109.0 7 1.59 and 1.68 247 and 17.6 1 1.3 37.5 - 24.0 CH 2 ethylene

[0103] Quantifications were performed from the integration of 1D 1< H NMR spectra using Topspin software.

[0104] The integrated signals for quantification of the different patterns are: Ethylene: Total signals between 0.5 ppm and 3.0 ppm by subtracting the aliphatic contributions of the other units of the copolymer. The calculation corresponds to 4 protons of the Ethylene unit. Form A: signal n°7 (4.86 ppm) corresponding to 2 protons. The proportion of form C is not directly accessible but can be calculated from signal n°3+8" by subtracting the contribution of form A. PB1-4: Signal between 5.71 ppm and 5.32 ppm corresponds to 2 protons (by removing the contribution of PB1-2). PB1-2: signal between 5.11 ppm and 4.92 ppm corresponds to 2 protons. Cyclohexane rings (1,2-cyclohexanediyl unit): signal between 1.80 ppm and 1.70 ppm corresponds to 2 protons.

[0105] Microstructure quantification is performed in molar percentage (mol%) as follows: % molaire d ′ un motif = intégrale H <mprescripts / > <none / > 1 d ′ un motif * 100 / Σ intégrale H <mprescripts / > <none / > 1 de chaque motif . b) Determination of the microstructure of ethylene-butadiene-farnesene copolymers:

[0106] Spectral characterization and microstructure measurements of Ethylene-butadiene-farnesene copolymer are performed by Nuclear Magnetic Resonance (NMR) spectroscopy. For these measurements, a Bruker Avance III HD 400 MHz spectrometer is used, equipped with a Bruker cryo-BBFO z-grad 5 mm probe. 1H experiments are recorded using a radiofrequency pulse with a flip angle of 30°, the number of repetitions is 128 with a recycle delay of 5 seconds. 1H-13C HSQC (Heteronuclear Single Quantum Coherence) and HMBC (Heteronuclear Multiple-Bond Correlation) NMR experiments are recorded with a number of repetitions of 128 and a number of increments of 128. The experiments are performed at 25 °C. 25 mg of sample are solubilized in 1 mL of deuterated orthodichlorobenzene (ODCB).The chemical shift axes 1< H and 13< C are calibrated relative to the protonated solvent impurity at δ 1H = 7.2 ppm (for the most deshielded signal) and δ 13C = 127 ppm (for the least deshielded signal).

[0107] Possible monomeric units in the copolymer are -CH 2 -CH(CH=CH 2 )-, -CH 2 -CH=CH-CH 2 -, -CH 2 -CH 2 -, the 1,2-cyclohexanediyl unit and the following structures, with R 1 and R 2 representing the polymer chain:

[0108] The signals of the insertion form of farnesene A were observed on the different recorded spectra. The signal of the -CH= group n°11" characteristic of the C form shows chemical shifts 1< H and 13< C identical to the -CH= groups n°3 and n°7.

[0109] The chemical shifts of the characteristic signals of the polymer are presented in Table 2 (Assignment of the 1< H and 13< C signals of the Ethylene-Butadiene-Farnesene copolymers other than those of the 1,3-butadiene units). Table 2 δ 1< H (ppm) δ 13< C (ppm) Group 5.25 125.0 7 5.15 125.0 3, 11'' 4.87 109.0 14 1.59 and 1.67 24.6 and 17.5 1, 13 1.28 38 - 24.0 CH 2 ethylene

[0110] Quantifications were performed from the integration of 1D 1< H NMR spectra using Topspin software.

[0111] The integrated signals for quantification of the different patterns are: Farnesene motif form A from signal n°14 CH 2 = for 2 protons, Farnesene motif form C from signals No. 3, 11" and No. 7 CH= (subtracting the contribution of form A), for 2 protons, Farnesene motif form B: from the signal n°11',specific to this form, for 1 proton. PB1-4: Signal between 5.71 ppm and 5.32 ppm corresponds to 2 protons (removing the PB1-2 contribution). PB1-2: signal between 5.11 ppm and 4.92 ppm corresponds to 2 protons. Cyclohexane rings (1,2-cyclohexanediyl unit): signal between 1.80 ppm and 1.70 ppm corresponds to 2 protons. Ethylene unit by integrating all aliphatic signals (from ~ 0.5 to 3 ppm) and subtracting the contribution of all other aliphatic units (PB1-4, PB1-2, EBR ring, farnesene forms A and C).

[0112] Microstructure quantification is performed in molar percentage (mol%) as follows: % molaire d ′ un motif = intégrale H <mprescripts / > <none / > 1 d ′ un motif * 100 / Σ intégrales H <mprescripts / > <none / > 1 de chaque motif I-2) Determination of the glass transition temperature of polymers:

[0113] The glass transition temperature is measured using a differential scanning calorimeter according to ASTM D3418 (1999). I-3) Determination of the macrostructure of polymers by size exclusion chromatography (SEC): a) Principle of measurement:

[0114] Size exclusion chromatography (SEC) separates macromolecules in solution according to their size using columns filled with a porous gel. Macromolecules are separated according to their hydrodynamic volume, with the largest being eluted first.

[0115] Combined with 3 detectors (3D), a refractometer, a viscometer and a 90° light scattering detector, SEC allows the absolute molar mass distribution of a polymer to be understood. The various number-average (Mn), weight-average (Mw) absolute molar masses and the dispersity (D = Mw / Mn) can also be calculated. b) Preparation of the polymer:

[0116] Each sample is solubilized in tetrahydrofuran at a concentration of approximately 1 g / L. The solution is then filtered through a 0.45µm porosity filter before injection. c) 3D SEC analysis:

[0117] To determine the number-average molar mass (Mn), and where appropriate the weight-average molar mass (Mw) and the polydispersity index (Ip) of polymers, the method below is used.

[0118] The number-average molar mass (Mn), weight-average molar mass (Mw) and polydispersity index of the polymer (hereinafter referred to as sample) are determined absolutely by triple detection size exclusion chromatography (SEC). Triple detection size exclusion chromatography has the advantage of measuring average molar masses directly without calibration.

[0119] The refractive index increment dn / dc value of the sample solution is measured online using the peak area detected by the refractometer (RI) of the liquid chromatography equipment. To apply this method, it must be ensured that 100% of the sample mass is injected and eluted through the column. The RI peak area depends on the sample concentration, the RI detector constant and the dn / dc value.

[0120] To determine the average molar masses, the previously prepared and filtered 1g / l solution is used and injected into the chromatographic system. The equipment used is a "WATERS alliance" chromatographic chain. The elution solvent is tetrahydrofuran containing 250 ppm of BHT (2,6-diter-butyl 4-hydroxy toluene), the flow rate is 1 mL.min -1< , the system temperature is 35° C and the analysis time is 60 min. The columns used are a set of three AGILENT columns with the trade name "PL GEL MIXED B LS". The injected volume of the sample solution is 100 µL. The detection system is composed of a Wyatt differential viscometer with the trade name “VISCOSTAR II”, a Wyatt differential refractometer with the trade name “OPTILAB T-REX” with a wavelength of 658 nm, a Wyatt multi-angle static light scattering detector with a wavelength of 658 nm and the trade name “DAWN HELEOS 8+”.

[0121] For the calculation of the number-average molar masses and the polydispersity index, the value of the refractive index increment dn / dc of the sample solution obtained above is integrated. The software for processing the chromatographic data is the “ASTRA de Wyatt” system. II-Characterization of rubber compositions : II-1) Vulcanization properties:

[0122] The measurements are carried out at 150°C with an oscillating chamber rheometer, according to DIN 53529 - Part 3 (June 1983). The evolution of the rheometric torque as a function of time describes the evolution of the stiffening of the composition as a result of the vulcanization reaction. The measurements are processed according to DIN 53529 - Part 2 (March 1983). Tα (e.g. T90) is the time required to achieve a conversion of α%, i.e. α% (e.g. 90%) of the difference between the minimum and maximum torques. II-2) Rigidity and hysteresis of rubber compositions:

[0123] The dynamic properties are measured on a viscoanalyzer (Metravib VA4000), according to standard D 5992-96. The response of a sample of vulcanized composition (cylindrical specimen 4 mm thick and 400 mm 2< in section) is recorded, subjected to a sinusoidal stress in alternating simple shear at an imposed stress of 0.7 MPa and at a frequency of 10 Hz, during a temperature sweep, from a minimum temperature lower than the Tg of the elastomers of the compositions up to a maximum temperature higher than 100°C. The results used are the complex dynamic shear modulus (G*) and the loss factor tanδ; the values ​​of G* are taken at a temperature of 60°C and the loss factor tanδ at 20°C and 60°C.

[0124] The stiffness and hysteresis results are expressed in base 100 relative to a control taken as a reference. A value less than 100 indicates a lower value than that of the control. III-Preparation of elastomers: Synthesis of an ethylene / 1,3-butadiene copolymer:

[0125] A copolymer of ethylene and 1,3-butadiene E1 is synthesized according to the following procedure: In a reactor containing methylcyclohexane, ethylene (Eth) and 1,3-butadiene (Btd) at 80°C in the proportions indicated in Table 3, butyloctylmagnesium (BOMAG) is added to neutralize the impurities in the reactor, then the catalytic system (see Table 3). At this time, the reaction temperature is regulated at 80°C and the polymerization reaction starts. The polymerization reaction takes place at a constant pressure of 8 bars. The reactor is supplied throughout the polymerization with ethylene and 1,3-butadiene in the proportions defined in Table 3. The polymerization reaction is stopped by cooling, degassing the reactor and adding ethanol. An antioxidant is added to the polymer solution. Copolymer E1 is recovered by drying in a vacuum oven until constant mass.

[0126] The catalytic system is a preformed catalytic system. It is prepared in methylcyclohexane from a metallocene, [Me 2 Si(Flu) 2 Nd(µ-BH 4 ) 2 Li(THF)], a co-catalyst, butyloctylmagnesium (BOMAG), and a preforming monomer, 1,3-butadiene, in the contents indicated in Table 3. It is prepared according to a preparation method in accordance with paragraph II.1 of patent application WO 2017093654 A1. Table 3 Metallocene concentration (mmol / L) Alkylating agent concentration (mmol / L) Preformation monomer / metal Nd molar ratio Feed composition (%mol Eth / Bdt) 0.07 0.36 90 80 / 20 Synthesis of ethylene / butadiene / farnesene copolymers:

[0127] Two copolymers E2 and E3 are synthesized according to the following procedure: In a reactor containing methylcyclohexane, ethylene, 1,3-butadiene and β-farnesene (Far) at 80°C in the proportions indicated in Table 4, butyloctylmagnesium (BOMAG) is added to neutralize the impurities in the reactor, then the catalytic system (see Table 4). At this time, the reaction temperature is regulated at 80°C and the polymerization reaction starts. The polymerization reaction takes place at a constant pressure of 8 bars. The reactor is supplied throughout the polymerization with ethylene, 1,3-butadiene and β-farnesene in the proportions defined in Table 4. 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 until constant mass.

[0128] The catalytic system is a preformed catalytic system. It is prepared in methylcyclohexane from a metallocene, [Me 2 Si(Flu) 2 Nd(µ-BH 4 ) 2 Li(THF)], a co-catalyst, butyloctylmagnesium (BOMAG), and a preforming monomer, 1,3-butadiene, in the contents indicated in Table 4. It is prepared according to a preparation method in accordance with paragraph II.1 of patent application WO 2017093654 A1. Table 4 Copolymer Metallocene concentration (mmol / L) Alkylating agent concentration (mmol / L) Preformation monomer / metal Nd molar ratio Feed composition (%mol Eth / Btd / Far) E2 0.10 0.4 90 84 / 9 / 7 E3 0.09 0,25 90 81 / 9 / 10 Synthesis of an ethylene / butadiene / myrcene copolymer:

[0129] An E4 copolymer is synthesized according to the following procedure: In a reactor containing methylcyclohexane, ethylene, 1,3-butadiene and myrcene (Myr) at 80°C in the proportions indicated in Table 5, butyloctylmagnesium (BOMAG) is added to neutralize the impurities in the reactor, then the catalytic system (see Table 5). At this point, the reaction temperature is regulated at 80°C and the polymerization reaction starts. The polymerization reaction takes place at a constant pressure of 8 bars. The reactor is supplied throughout the polymerization with ethylene, 1,3-butadiene and myrcene in the proportions defined in Table 5. 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 constant mass.

[0130] The catalytic system is a preformed catalytic system. It is prepared in methylcyclohexane from a metallocene, [Me2Si(Flu)2Nd(µ-BH4)2Li(THF)], a co-catalyst, butyloctylmagnesium (BOMAG), and a preforming monomer, 1,3-butadiene, in the contents indicated in Table 5. It is prepared according to a preparation method in accordance with paragraph II.1 of patent application WO 2017093654 A1. Table 5 Copolymer Metallocene concentration (mmol / L) Alkylating agent concentration (mmol / l) Preformation monomer / metal Nd molar ratio Feed composition (%mol Eth / Btd / Myr) E4 0.09 0.4 90 73 / 15 / 12

[0131] The microstructure of elastomers E1 to E4 is shown in Table 6, which indicates the molar ratios of ethylene units (Eth), 1,3-butadiene units, 1,2-cyclohexanediyl units (cycle), β-farnesene units or myrcene units. Table 6 also shows the molar ratio of β-farnesene or myrcene units according to whether they are of 1,4 configuration, 1,2 configuration or 3,4 configuration and the number-average molar mass measured according to paragraph I-3). Table 6 Elastomer Eth Btd cycle Far or Myr 1.4 1.2 3.4 Mn (g / mol) E1 78 14 8 - - - - 128888 E2 79 8 5 8 (Far) 37 <1 63 161000 E3 76 8 5 11 (Far) 36 <1 64 200800 E4 71 15 6 8 (Myr) 37 <1 63 133000 IV-Preparation of rubber compositions:

[0132] Rubber compositions whose formulation expressed in pce (parts by weight per hundred parts of elastomer) is shown in Table 7, were prepared in an internal mixer into which the copolymer, the reinforcing filler, and the various other ingredients except for the vulcanization system are successively introduced. Thermomechanical work (non-productive phase) is then carried out in one step, lasting a total of approximately 5 minutes, until a maximum "fall" temperature of 150°C is reached. The mixture thus obtained is recovered, cooled, and then sulfur and the accelerator are incorporated on a mixer (homo-finisher) at 40°C, mixing everything (productive phase) for approximately ten minutes. The compositions thus obtained are then calendered either in the form of plates (thickness of 2 to 3 mm) or thin sheets of rubber for the measurement of their physical or mechanical properties after vulcanization at 150°C.The applied curing time, T(99), is the time required for the composition torque to reach 99% of the composition's maximum torque.

[0133] Composition C1 which contains elastomer E1, a copolymer of ethylene and 1,3-butadiene, is a composition not in accordance with the invention. Compositions C2 to C4 which respectively contain elastomers E2 to E4 are compositions in accordance with the invention. Table 7 Composition C1 C2 C3 C4 Elastomer E1 100 - - - E2 Elastomer - 100 - - Elastomer E3 - - 100 - E4 Elastomer - - - 100 Carbon black (1) 4 4 4 4 Silica (2) 98 98 98 98 Liquid plasticizing agent (3) 4 4 4 4 Plasticizing resin (4) 47 47 47 47 Antioxidant 5.4 5.4 5.4 5.4 Antiozonant wax 2.5 2.5 2.5 2,5 Coupling agent (5) 10 10 10 10 Stearic acid (6) 4 4 4 4 DPG (7) 2.1 2.1 2.1 2.1 ZnO (8) 1 1 1 1 Accelerator (9) 2.4 2.4 2.4 2.4 Sulfur 1 1 1 1 (1) N234 (2) "Zeosil 1165 MP" from Solvay-Rhodia in the form of microbeads (3) MES / HPD (Catenex SNR from Shell) (4) C9 / Dicyclopentadiene hydrocarbon resin "Escorez 5600" from EXXON (Tg = 52°C) (5) TESPT ("Si69" from Evonik) (6) Stearin "Pristerene 4931" from Uniquema (7) Diphenylguanidine (8) Industrial grade Zinc Oxide from Umicore (9) N-cyclohexyl-2-benzothiazol-sulfenamide ("Santocure CBS" from Flexsys) V-Results:

[0134] The results are shown in Table 8. They are expressed on a base of 100 relative to the composition C1 taken as a control. A value lower than 100 indicates a lower value than that of the control. Table 8 Composition C1 C2 C3 C4 G* 60°C 100 63 70 85 tanδ 20°C 100 90 85 96 tanδ 60°C 100 91 78 87 T90 100 43 41 54

[0135] Compositions C2 to C4 have lower rigidity than composition C1, even though the ethylene levels are comparable. The hysteresis of compositions C2 to C4 is also lower than that of C1. The time required for vulcanization of the rubber compositions is also greatly reduced given the T90 values ​​which are much lower than 100. Both the curing, hysteresis and rigidity properties of the rubber compositions according to the invention are improved.

Claims

1. Rubber composition which comprises a reinforcing filler, a vulcanization system and more than 50 to 100 phr of an elastomer which contains more than 50 mol% of ethylene units and which is a copolymer of ethylene, of a first 1,3-diene which is 1,3-butadiene, isoprene or mixture thereof, and of a second 1,3-diene of formula (I), CH2=CR-CH=CH2 (I), the symbol R representing an unsaturated aliphatic hydrocarbon chain having 3 to 20 carbon atoms.

2. Rubber composition according to Claim 1, in which the copolymer contains more than 60 mol% of ethylene units, preferably at least 70 mol% of ethylene units.

3. Rubber composition according to either one of Claims 1 and 2, in which the copolymer contains at most 85 mol% of ethylene units.

4. Rubber composition according to any one of Claims 1 to 3, in which the copolymer contains less than 30 mol%, preferentially at most 20 mol% of units of the second 1,3-diene, more preferentially at most 15 mol% of units of the second 1,3-diene of formula (I).

5. Rubber composition according to any one of Claims 1 to 4, in which the copolymer contains less than 30 mol% of units of the first 1,3-diene or less than 20 mol% of units of the first 1,3-diene.

6. Rubber composition according to any one of Claims 1 to 5, in which the copolymer contains at least 1 mol% of units of the second 1,3-diene.

7. Rubber composition according to any one of Claims 1 to 6, in which the copolymer contains at least 5 mol% of units of the second 1,3-diene.

8. Rubber composition according to any one of Claims 1 to 7, in which the copolymer contains less than 80 mol% of ethylene units.

9. Rubber composition according to any one of Claims 1 to 8, in which the first 1,3-diene is 1,3-butadiene.

10. Rubber composition according to any one of Claims 1 to 9, in which the second 1,3-diene is myrcene, β-farnesene or a mixture of myrcene and β-farnesene.

11. Rubber composition according to any one of Claims 1 to 10, in which the copolymer is a statistical copolymer.

12. Rubber composition according to any one of Claims 1 to 11, in which the reinforcing filler is present at a content ranging from 30 to 200 phr.

13. Rubber composition according to any one of Claims 1 to 12, in which the reinforcing filler comprises a silica which represents more than 50% by weight of the reinforcing filler.

14. Tyre which comprises a tread, which tyre comprises a rubber composition defined in any one of Claims 1 to 13, preferably in the tread thereof.