Rubber composition

Abstract

The present invention relates to a rubber composition comprising a highly saturated diene elastomer, which is a copolymer containing 1, 3-diene units and more than 50 mol% ethylene units and bearing at one chain end a functional group of the formula-CH2-CH (CH3)-COOZ, a crosslinking system and a reinforcing filler, wherein Z is a hydrocarbyl group substituted with a tertiary amine functional group, the reinforcing filler comprises silica or carbon black, and wherein the highly saturated diene elastomer is a copolymer of ethylene and 1, 3-diene or a copolymer of ethylene, 1, 3-diene and an alpha-monoolefin.

Description

Technical Field

[0001] The field of the invention is that of rubber compositions which can be used in particular for the production of tires and which comprise a reinforcing filler and a highly saturated diene elastomer. Background Art

[0002] It is well known that tires must meet a number of often conflicting technical requirements, including low rolling resistance, high wear resistance, and high dry and wet grip. In recent years, energy-saving "green tires", especially those intended for passenger vehicles, have improved this performance compromise, especially in terms of rolling resistance and wear resistance, by using special new low-hysteresis rubber compositions characterized by being mainly reinforced with highly dispersible silica (HDS), which is comparable to conventional tire-grade carbon black in terms of reinforcement capabilities.

[0003] In document WO 2014114607, the Applicant describes the use of highly saturated diene elastomers in rubber compositions for tires in order to modify the performance compromise between rolling resistance and wear. These highly saturated diene elastomers contain 1,3-diene units and greater than 50 mol % of ethylene units.

[0004] In the course of the work, the Applicant developed a novel low-hysteresis rubber composition comprising a weakly saturated diene elastomer and a reinforcing filler containing silica or carbon black, also with the aim of reducing the rolling resistance of the tire. In fact, contrary to all expectations, a low-hysteresis rubber composition was developed comprising a highly saturated diene elastomer comprising, as functional group at the end of the elastomer chain, a single methacrylate monomer unit bearing an amine function. Summary of the invention

[0005] First, the present invention provides a rubber composition comprising a highly saturated diene elastomer, a crosslinking system and a reinforcing filler, wherein the highly saturated diene elastomer contains 1,3-diene units and more than 50 mol % of ethylene units and carries a crosslinking system and a reinforcing filler at one of its chain ends. 2 -CH(CH 3 )-COOZ, Z is a hydrocarbon group substituted by a tertiary amine functional group, the reinforcing filler includes silica or carbon black, and the highly saturated diene elastomer is a copolymer of ethylene and 1,3-diene or a copolymer of ethylene, 1,3-diene and α-monoolefin.

[0006] Secondly, the present invention provides a tire comprising a tread, the tire comprising the rubber composition according to the present invention, preferably comprising the rubber composition according to the present invention in the tread of the tire. DETAILED DESCRIPTION

[0007] Any numerical interval represented by the expression "between a and b" means a numerical range greater than "a" and less than "b" (i.e., does not include the end values ​​a and b), while any numerical interval represented by the expression "a to b" means a numerical range extending from "a" to "b" (i.e., includes the strict end values ​​a and b).

[0008] The abbreviation "phr" means parts by weight per hundred parts of elastomer (or the sum of the elastomers, if more than one elastomer is present).

[0009] In the present disclosure, formula (C n -C m )alkyl is used to represent an alkyl group having n to m carbon atoms, n is an integer greater than or equal to 1, and m is an integer greater than n. For example, (C 1 -C 2 )alkyl represents an alkyl group having 1 to 2 carbon atoms. Similarly, (C n -C m ) The alkoxy group represents an alkoxy group having n to m carbon atoms.

[0010] The compounds mentioned in this specification may be compounds of fossil origin or may be bio-based compounds. In the case where the compounds are bio-based compounds, they may be partially or completely produced from biomass or obtained from renewable raw materials produced from biomass. Similarly, the compounds mentioned may also originate from the recycling of used materials, i.e. they may be partially or completely derived from a recycling process, or obtained by raw materials that themselves originate from a recycling process.

[0011] In the present invention, "tire" is understood to mean a pneumatic tire or a non-pneumatic tire. A pneumatic tire generally comprises two beads intended to come into contact with the rim, a crown consisting of at least one crown reinforcement and a tread, two sidewalls, the tire being reinforced by a carcass reinforcement anchored in the two beads. On the other hand, a non-pneumatic tire generally comprises a base (for example designed to be mounted on a rigid rim), a crown reinforcement (ensuring connection with the tread) and a deformable structure (for example spokes, ribs or a grid) arranged between the base and the crown. Such non-pneumatic tires do not necessarily include sidewalls. For example, non-pneumatic tires are described in documents WO03 / 018332 and FR2898077. According to any embodiment of the invention, the tire according to the invention is preferably a pneumatic tire.

[0012] The expression "based on" used to define the components of the catalytic system (or catalytic composition) is understood to mean a mixture of these components, or a product of the reaction of some or all of these components with one another.

[0013] Elastomers that can be used for the purposes of the present invention are highly saturated diene elastomers, provided that ethylene units represent more than 50 mol % of all the monomer units in the highly saturated diene elastomer. Preferably, the highly saturated diene elastomer is a statistical copolymer.

[0014] As is well known, the expression "ethylene unit" refers to the -(CH 2 -CH 2 )-units. The ethylene units in the highly saturated diene elastomer preferably represent at least 60 mol %, more preferably at least 65 mol % of all the monomer units in the highly saturated diene elastomer. Even more preferably, the ethylene units in the highly saturated diene elastomer represent at least 70 mol % of all the monomer units in the highly saturated diene elastomer.

[0015] Preferably, ethylene units in the highly saturated diene elastomer represent less than 90 mol % of all the monomer units in the highly saturated diene elastomer. More preferably, ethylene units represent at most 85 mol % of all the monomer units in the highly saturated diene elastomer. Even more preferably, ethylene units represent at most 80 mol % of all the monomer units in the highly saturated diene elastomer.

[0016] According to an advantageous embodiment, the highly saturated diene elastomer comprises from 60 mol% to less than 90 mol% of ethylene units, in particular from 60 mol% to 85 mol% of ethylene units, the molar percentages being calculated on the basis of all the monomer units in the highly saturated diene elastomer. More advantageously, the highly saturated diene elastomer comprises from 60 mol% to 80 mol% of ethylene units, the molar percentages being calculated on the basis of all the monomer units in the highly saturated diene elastomer.

[0017] According to another advantageous embodiment, the highly saturated diene elastomer comprises from 65 mol% to less than 90 mol% of ethylene units, in particular from 65 mol% to 85 mol% of ethylene units, the molar percentages being calculated on the basis of all the monomer units in the highly saturated diene elastomer. More advantageously, the highly saturated diene elastomer comprises from 65 mol% to 80 mol% of ethylene units, the molar percentages being calculated on the basis of all the monomer units in the highly saturated diene elastomer.

[0018] According to yet another advantageous embodiment of the invention, the highly saturated diene elastomer comprises from 70 mol% to less than 90 mol% of ethylene units, in particular from 70 mol% to 85 mol% of ethylene units, the molar percentages being calculated on the basis of all the monomer units in the highly saturated diene elastomer. More advantageously, the highly saturated diene elastomer comprises from 70 mol% to 80 mol% of ethylene units, the molar percentages being calculated on the basis of all the monomer units in the highly saturated diene elastomer.

[0019] Highly saturated diene elastomers also comprise 1,3-diene units resulting from the polymerization of 1,3-dienes. As is known, the expressions “1,3-diene units” or “diene units” mean units resulting, for example in the case of isoprene, from 1,4-, 1,2- or 3,4-addition insertion into a 1,3-diene.

[0020] According to one embodiment of the invention, 1,3-diene units represent at least 35 mol % of the monomer units in the highly saturated diene elastomer.

[0021] According to one embodiment of the invention, 1,3-diene units represent less than 35 mol % of the monomer units in the highly saturated diene elastomer.

[0022] The highly saturated diene elastomer may contain α-monoolefin units. α-Monoolefin is understood to mean an α-olefin containing at least 3 carbon atoms and having a single carbon-carbon double bond (excluding double bonds in aromatic compounds). For example, styrene is considered to be an α-monoolefin. The α-monoolefin is preferably aromatic, more preferably styrene or styrene whose benzene ring is substituted by one or more alkyl groups. Even more preferably, the α-monoolefin is styrene.

[0023] The 1,3-dienes are single compounds, i.e. only single (one) 1,3-dienes, or mixtures of 1,3-dienes having different chemical structures. For example, 1,3-dienes having 4 to 20 carbon atoms are suitable as 1,3-dienes. Preferably, the 1,3-dienes are 1,3-butadiene, isoprene, myrcene, β-farnesene or mixtures thereof, such as mixtures of at least two thereof. The mixture of at least two thereof is advantageously a mixture containing 1,3-butadiene. The mixture of 1,3-dienes is preferably a mixture of 1,3-butadiene and myrcene or a mixture of 1,3-butadiene and β-farnesene.

[0024] According to a particularly preferred embodiment of the present invention, the 1,3-diene is a mixture of 1,3-butadiene and myrcene or a mixture of 1,3-butadiene and β-farnesene.

[0025] According to another particularly preferred embodiment of the present invention, the 1,3-diene is 1,3-butadiene.

[0026] The highly saturated diene elastomer is advantageously a copolymer of ethylene and 1,3-diene, in which case the units constituting the highly saturated diene elastomer are units resulting from the polymerization of 1,3-diene and ethylene. In particular, the highly saturated diene elastomer is a copolymer of ethylene and 1,3-butadiene or a copolymer of ethylene, 1,3-butadiene and myrcene or a copolymer of ethylene, 1,3-butadiene and β-farnesene. The highly saturated diene elastomer is more advantageously a statistical copolymer of ethylene and 1,3-butadiene or a statistical copolymer of ethylene, 1,3-butadiene and myrcene or a statistical copolymer of ethylene, 1,3-butadiene and β-farnesene.

[0027] According to a particularly preferred embodiment of the invention, in particular when the 1,3-diene is 1,3-butadiene or a mixture of 1,3-dienes, one of which is 1,3-butadiene, the highly saturated diene elastomer contains cyclic 1,2-cyclohexane units of formula (I).

[0028]

[0029] The presence of saturated 6-membered 1,2-cyclohexane ring units of formula (I) in highly saturated diene elastomers is probably due to a very specific series of insertions of ethylene and 1,3-butadiene into the polymer chain during its growth. The mechanism for obtaining this microstructure is described, for example, in Macromolecules (2009, 42, 3774-3779). When a highly saturated diene elastomer comprises units of formula (I), it preferably contains up to 15 mol % of units of formula (I), this percentage being expressed relative to all monomer units.

[0030] Another characteristic of highly saturated diene elastomers is that they carry at one of their chain ends a residue of the formula -CH 2 -CH(CH 3 )-COOZ functional group. The functional group is usually covalently attached to the end of the highly saturated diene elastomer chain. 2 ) is covalently bonded to a carbon atom of a terminal monomer unit constituting the highly saturated diene elastomer.

[0031] The symbol Z represents a hydrocarbon group substituted by a tertiary amine functional group. Preferably, Z represents a saturated acyclic hydrocarbon group substituted by a tertiary amine functional group, and the saturated acyclic hydrocarbon group substituted by a tertiary amine functional group is advantageously an alkyl group having 1 to 3 carbon atoms. The tertiary amine functional group is preferably an N,N-dialkylamino group, and the alkyl groups replacing the nitrogen atoms preferably each have 1 to 3 carbon atoms, and better still have 1 carbon atom or 2 carbon atoms. According to any embodiment of the present invention, the alkyl groups replacing the nitrogen atoms are preferably the same.

[0032] According to a most particularly preferred embodiment, Z represents N,N-di(C 1 -C 3 ) alkylamino (C 1 -C 3 )alkyl, preferably 2-(N,N-dimethylamino)ethyl, 2-(N,N-diethylamino)ethyl or 2-(N,N-diisopropylamino)ethyl, more preferably 2-(N,N-dimethylamino)ethyl.

[0033] The functionalized highly saturated diene elastomers that can be used for the purposes of the present invention can be prepared by a process comprising the following consecutive steps a), b) and c),

[0034] - step a) is the polymerization of a monomer mixture containing 1,3-diene and ethylene and, where appropriate, α-monoolefins in the presence of a catalytic system based at least on a metallocene of formula (Ia) and an organomagnesium compound

[0035] {P(Cp 1 )(Cp 2 )Nd(BH 4 ) (1+y)- L y -N x} (Ia)

[0036] Cp 1 and Cp 2 are the same or different and are selected from fluorenyl, cyclopentadienyl and indenyl, which groups are substituted or unsubstituted,

[0037] P is the bridge Cp 1 and Cp 2 Two groups and groups containing silicon atoms or carbon atoms,

[0038] Nd represents a neodymium atom,

[0039] L represents an alkali metal selected from lithium, sodium and potassium,

[0040] N represents an ether molecule,

[0041] x is an integer or non-integer equal to or greater than 0,

[0042] y is an integer equal to or greater than 0,

[0043] The olefin is ethylene or a mixture of ethylene and α-monoolefins.

[0044] - step b) is to react methacrylic acid ester with the product of the polymerization reaction in step a),

[0045] - Step c) is a chain termination reaction.

[0046] Step a) of the process consists in polymerizing a monomer mixture containing 1,3-diene and ethylene and, where appropriate, α-monoolefins, which makes it possible to prepare chains of highly saturated diene elastomer: the growing chains are intended to react in the next step (step b) with a functionalizing agent, methacrylate.

[0047] Preferably, the monomer mixture in step a) contains more than 50 mol % of ethylene, this percentage being expressed relative to the total number of moles of the monomers in the monomer mixture in step a). When the monomer mixture contains α-monoolefins (such as styrene), it preferably contains less than 40 mol % of α-monoolefins, this percentage being expressed relative to the total number of moles of the monomers in the monomer mixture in step a). Preferably, the monomer mixture in step a) is a mixture of 1,3-diene and ethylene.

[0048] The copolymerization of the monomer mixture can be carried out according to patent applications WO 2007 / 054223 A2 and WO 2007 / 054224 A2 using a catalytic system consisting of a metallocene and an organomagnesium compound.

[0049] In the present patent application, "metallocene" is understood to mean an organometallic complex whose metal (in this case a neodymium atom) is bound to a so-called ligand and which consists of Cp atoms linked together by bridges P. 1 and Cp 2 These Cp 1 and Cp 2 The groups are identical or different and are selected from fluorenyl, cyclopentadienyl and indenyl, and these groups may be substituted or unsubstituted.

[0050] According to the present invention, the metallocene used as an essential component in the catalytic system corresponds to the formula (Ia)

[0051] {P(Cp 1 )(Cp 2 )Nd(BH 4 ) (1+y)- L y -N x} (Ia)

[0052] P is the bridge Cp 1 and Cp 2 Two groups and groups containing silicon atoms or carbon atoms,

[0053] Cp 1 and Cp 2 are the same or different and are selected from fluorenyl, cyclopentadienyl and indenyl, which groups are substituted or unsubstituted,

[0054] Nd represents a neodymium atom,

[0055] L represents an alkali metal selected from lithium, sodium and potassium,

[0056] N represents an ether molecule,

[0057] x is an integer or non-integer equal to or greater than 0,

[0058] y is an integer equal to or greater than 0.

[0059] Any ether which is able to complex alkali metals, in particular diethyl ether, methyltetrahydrofuran and tetrahydrofuran, is suitable as ether.

[0060] Substituted cyclopentadienyl, fluorenyl and indenyl groups include substituted alkyl groups having 1 to 6 carbon atoms or aryl groups having 6 to 12 carbon atoms or trialkylsilyl groups (such as SiMe 3 The choice of free radical also depends on the availability of parent molecules, which are substituted cyclopentadienes, fluorenes and indenes, as they are commercially available or can be easily synthesized.

[0061] Substituted fluorenyl groups include those substituted at positions 2, 7, 3 or 6, particularly 2,7-di(tert-butyl)fluorenyl and 3,6-di(tert-butyl)fluorenyl. As shown in the figure below, positions 2, 3, 6 and 7 represent the positions of the carbon atoms of the ring, respectively, and position 9 corresponds to the carbon atom to which the bridge P is attached.

[0062]

[0063] Substituted cyclopentadienyl groups include those substituted at position 2 (or 5) or position 3 (or 4), particularly those substituted at position 2, more particularly tetramethylcyclopentadienyl. Position 2 (or 5) refers to the position of the carbon atom adjacent to the carbon atom to which the bridge P is attached, as shown in the following figure. It should be noted that substitution at position 2 or 5 is also referred to as substitution at the alpha position of the bridge.

[0064]

[0065] Substituted indenyl groups include those substituted at position 2, more particularly 2-methylindenyl or 2-phenylindenyl. Position 2 refers to the position of the carbon atom adjacent to the carbon atom to which the bridge P is attached, as shown in the figure below.

[0066]

[0067] Preferably, Cp 1 and Cp 2 The same or different, is a cyclopentadienyl, a substituted fluorenyl, a substituted indenyl or a substituted indenyl of formula C 13 H 8 Fluorenyl or formula C 9 H 7 More preferably, Cp1 and Cp 2 The same or different, selected from substituted fluorenyl and formula C 13 H 8 Unsubstituted fluorenyl. When Cp 1 and Cp 2 The same and each expression C 13 H 8 This is advantageous when the fluorenyl group is an unsubstituted fluorenyl group (represented by the symbol Flu).

[0068] Preferably, the linking group Cp 1 and Cp 2 The bridge P is of the formula ZR 1 R 2 , where Z represents a silicon atom or a carbon atom, R 1 and R 2 are the same or different and each represents an alkyl group containing 1 to 20 carbon atoms, preferably a methyl group. 1 R 2 In the formula (a), Z advantageously represents a silicon atom, Si.

[0069] Even more preferably, the metallocene is of formula (I-1), (I-2), (I-3), (I-4) or (I-5):

[0070] [Me 2 Si(Flu) 2 Nd(μ-BH 4 ) 2 Li(THF)] (I-1)

[0071] [{Me 2 SiFlu 2 Nd(μ-BH 4 ) 2 Li(THF)} 2 ] (I-2)

[0072] [Me 2 SiFlu 2 Nd(μ-BH 4 )(THF)] (I-3)

[0073] [{Me 2 SiFlu 2 Nd(μ-BH 4 )(THF)} 2 ] (I-4)

[0074] [Me 2 SiFlu 2 Nd(μ-BH 4 )] (I-5)

[0075] Where Flu represents C 13 H 8 Group.

[0076] The metallocene that can be used for the synthesis of catalyst system can be the form of crystalline powder or non-crystalline powder, or be single crystal form.Metallocene can be monomeric form or dimer form, and these forms depend on the preparation method of metallocene, as described in patent application WO 2007054224 A2 or WO 2007054223A2 for example.Metallocene can be conventionally prepared by the method similar to the method described in patent application WO 2007054224A2 or WO 2007054223 A2, especially by reacting the borohydride of alkali metal salt of part and rare earth metal neodymium in suitable solvent (for example ether (such as diethyl ether or tetrahydrofuran), or any other solvent well known to persons skilled in the art) under inertia and anhydrous conditions to prepare.After the reaction, by technology well known to persons skilled in the art, for example, filter or precipitate from the second solvent, thereby metallocene is separated from byproduct of reaction.Finally, metallocene is dried and separated in solid form.

[0077] The organomagnesium compound is another basic component of the catalyst system and is a co-catalyst of the catalyst system. Generally, the organomagnesium compound can be a diorganomagnesium reagent or an organomagnesium halide. Preferably, the organomagnesium compound is of formula (IIa) or (IIb), wherein R 3 and R 4 are the same or different, representing a carbon-based group, X is a halogen atom,

[0078] Mg 3 R 4 (IIa)

[0079] XOtM 5 (IIb)

[0080] A "carbonyl group" is understood to mean a group containing one or more carbon atoms. A carbonyl group may be a hydrocarbon group (hydrocarbonyl group) or a heterohydrocarbon group, i.e. a group containing one or more heteroatoms in addition to carbon atoms and hydrogen atoms. Suitable organomagnesium compounds having a heterohydrocarbon group include the compounds described as transfer agents in patent application WO 2016 / 092227 A1. 3 and R 4 The carbyl group represented by is preferably a hydrocarbon group.

[0081] By the symbol R 3 and R 4 The carbonyl groups represented can be aliphatic or aromatic. They can contain one or more heteroatoms, such as oxygen atoms, nitrogen atoms, silicon atoms or sulfur atoms. Preferably, they are alkyl, phenyl or aryl. They can contain 1 to 20 carbon atoms.

[0082] Represented as R 3 and R 4 The alkyl group may contain 2 to 10 carbon atoms and is especially ethyl, butyl or octyl.

[0083] Represented as R 3 and R 4 The aryl group may contain 7 to 20 carbon atoms and is especially phenyl substituted by one or more alkyl groups (eg methyl, ethyl, isopropyl).

[0084] R 3 and R 4 Preferred is an alkyl group having 2 to 10 carbon atoms, a phenyl group having 7 to 20 carbon atoms, or an aryl group.

[0085] According to a particular embodiment of the present invention, R 3 A benzene ring comprising two carbon atoms substituted: one of the two carbon atoms is substituted by a methyl, ethyl or isopropyl group, or forms a ring with the carbon atom closest thereto, the second carbon atom is substituted by a methyl, ethyl or isopropyl group, a magnesium atom is located at an ortho position to each of the two carbon atoms, R 4 According to this particular embodiment, R 3 Advantageously, it is 1,3-dimethylphenyl, 1,3-diethylphenyl, mesityl or 1,3,5-triethylphenyl, R 4 Advantageously it is ethyl, butyl or octyl.

[0086] According to another specific embodiment of the present invention, R 3 and R 4 is an alkyl group containing 2 to 10 carbon atoms, especially ethyl, butyl or octyl.

[0087] Examples of suitable organomagnesium compounds are butylethylmagnesium, butyloctylmagnesium, ethylmagnesium chloride, butylmagnesium chloride, ethylmagnesium bromide, butylmagnesium bromide, octylmagnesium chloride, octylmagnesium bromide, 1,3-dimethylphenylbutylmagnesium, 1,3-diethylphenylethylmagnesium, butylmesitylmagnesium, ethylmesitylmagnesium, 1,3-diethylphenylbutylmagnesium, 1,3-diethylphenylethylmagnesium, 1,3-diisopropylphenylbutylmagnesium, 1,3-diisopropylphenylethylmagnesium, 1,3,5-triethylphenylbutylmagnesium, 1,3,5-triethylphenylethylmagnesium, 1,3,5-triisopropylphenylbutylmagnesium and 1,3,5-triisopropylphenylethylmagnesium.

[0088] The compounds of formula (IIa) and (IIb) are well known as Grignard reagents, and some of them are even commercial products. For their synthesis, reference can be made to, for example, the compilation volumes of "Organic Synthesis".

[0089] As with any organomagnesium compound, the organomagnesium compound constituting the catalyst system, in particular the organomagnesium compound of formula (IIa) or (IIb), may be in the form of a monomeric substance or in the form of a polymeric substance. For example, the organomagnesium compound (IIa) may be in the form of a monomeric substance (MgR 3 R 4 ) 1 , or in the form of polymeric substances (MgR 3 R 4 ) p (p is an integer greater than 1), especially a dimer (MgR 3 R 4 ) 2 .

[0090] Furthermore, whether in the form of a monomer or a polymer, the organomagnesium compound may also be in the form of a complex with one or more molecules of a solvent (preferably an ether such as diethyl ether, tetrahydrofuran or methyltetrahydrofuran).

[0091] According to any embodiment of the present invention, the organomagnesium compound is preferably of formula (IIa).

[0092] The amounts of the cocatalyst and metallocene reacted such that the ratio of the molar number of Mg of the cocatalyst to the molar number of the rare earth metal (neodymium) of the metallocene is preferably 0.5 to 200, more preferably 1 to less than 20. The value range of 1 to less than 20 is particularly advantageous for obtaining copolymers of high molar mass.

[0093] According to one embodiment, the catalytic system is conventionally prepared by a method similar to that described in patent application WO 2007054224A2 or WO2007054223 A2. For example, the cocatalyst (in this case an organomagnesium compound) and the metallocene are reacted in a hydrocarbon solvent, typically at a temperature ranging from 20° C. to 80° C., for a period of time (between 5 minutes and 60 minutes). The catalytic system is typically prepared in an aliphatic hydrocarbon solvent (such as methylcyclohexane) or an aromatic hydrocarbon solvent (such as toluene), preferably in an aliphatic hydrocarbon solvent (such as methylcyclohexane). Typically, after synthesis, the catalytic system is used as is in step a).

[0094] According to another embodiment, the catalytic system is prepared by a method similar to that described in patent application WO 2017093654A1 or patent application WO2018020122 A1: it is called preformed type. For example, the organomagnesium compound and the metallocene are reacted in a hydrocarbon solvent, usually at a temperature of 20°C to 80°C for 10 to 20 minutes to obtain a first reaction product, and then the preformed monomer is reacted with the first reaction product at a temperature ranging from 40°C to 90°C for 1 hour to 12 hours. The preformed monomer is preferably used in a molar ratio (preformed monomer / metal of metallocene) ranging from 5 to 1000, preferably 10 to 500. Before being used for polymerization, the preformed catalytic system can be stored under an inert atmosphere, especially at a temperature ranging from -20°C to room temperature (23°C). The preformed catalytic system has a preformed monomer selected from 1,3-diene, ethylene and mixtures thereof as its essential component. In other words, in addition to the metallocene and the cocatalyst, the "preformed" catalytic system also contains a preformed monomer. The 1,3-diene used as the pre-formed monomer may be 1,3-butadiene, isoprene or a diolefin of the formula CH 2 =CR 6 -CH=CH 2 1,3-diene, symbol R 6 denotes a hydrocarbon radical having 3 to 20 carbon atoms, in particular myrcene or β-farnesene. The preformed monomer is preferably 1,3-butadiene.

[0095] The catalytic system is usually present in a solvent, which is preferably a solvent for preparing the catalytic system. The concentration of the rare earth metal (i.e., neodymium) of the metallocene is preferably in the range of 0.0001 mol / L to 0.2 mol / L, more preferably in the range of 0.001 mol / L to 0.03 mol / L.

[0096] As with any synthesis carried out in the presence of an organometallic compound, the synthesis of the metallocene, the synthesis of the organomagnesium compound and the synthesis of the catalytic system are carried out under anhydrous conditions and in an inert atmosphere. Typically, the reaction is started using anhydrous solvents and compounds under anhydrous nitrogen or argon.

[0097] The polymerization of the monomer mixture is preferably carried out continuously or discontinuously in a solution. The polymerization solvent is generally a hydrocarbon solvent, preferably an aliphatic hydrocarbon solvent. A particularly suitable example of an aliphatic hydrocarbon solvent is methylcyclohexane. The monomer mixture can be introduced into a reactor containing a polymerization solvent and a catalyst system, or conversely, the catalyst system can be introduced into a reactor containing a polymerization solvent and a monomer mixture. The monomer mixture and the catalyst system can be introduced simultaneously into a reactor containing a polymerization solvent, especially in the case of continuous polymerization. The polymerization is usually carried out under anhydrous conditions and in the absence of oxygen and optionally in the presence of an inert gas. The polymerization temperature ranges generally from 40°C to 150°C, preferably from 40°C to 120°C. Those skilled in the art adjust the polymerization conditions, such as the polymerization temperature, the concentration of each reagent, and the pressure in the reactor, according to the composition of the monomer mixture, the polymerization reactor, and the desired microstructure and macrostructure of the copolymer chain.

[0098] The polymerization is preferably carried out under a constant monomer pressure. One monomer or each monomer can be added continuously to the polymerization reactor, in which case the polymerization reactor is a feed reactor. This embodiment is most particularly suitable for statistical incorporation of monomers. Preferably, the polymerization in step a) is a statistical polymerization, which is reflected in the statistical incorporation of monomers in the monomer mixture used in step a).

[0099] Once the desired degree of monomer conversion has been achieved in the polymerization reaction in step a), step b) is carried out.

[0100] Step b) of the process according to the invention combines a functionalizing agent methacrylate with the reaction product of step a), so that at one end of the highly saturated diene elastomer chain produced at the end of step a) a methacrylate monomer unit with a functional group useful for the purposes of the invention is introduced. Step b) is a functionalization reaction at the end of the highly saturated diene elastomer chain, without subsequent polymerization of the methacrylate.

[0101] Methacrylates are "functional" methacrylates and are of the formula CH 2 =CCH 3 COOR', R' is a hydrocarbon group substituted by a tertiary amine functional group.

[0102] The hydrocarbon group of symbol R' is preferably saturated. The number of carbon atoms in the hydrocarbon group of symbol R' is not limited per se. The hydrocarbon group may contain up to 20 carbon atoms. Preferably, the hydrocarbon group of symbol R' contains 1 to 6 carbon atoms, more preferably 1 to 3 carbon atoms. Preferably, the hydrocarbon group of symbol R' is a saturated acyclic hydrocarbon group substituted by the tertiary amine functional group.

[0103] Preferably, the methacrylate is of the formula CH 2 =CCH 3COOR', wherein R' is an alkyl group substituted by a dialkylamino group (a saturated acyclic hydrocarbon group), in particular, the methacrylate is N,N-di(C 1 -C 3 ) alkylamino (C 1 -C 3 ) alkyl methacrylate, preferably 2-(dimethylamino)ethyl methacrylate, 2-(diethylamino)ethyl methacrylate, 2-(diisopropylamino)ethyl methacrylate, more preferably 2-(dimethylamino)ethyl methacrylate.

[0104] The methacrylates which can be used for the purposes of the present invention may be commercial products. These are generally commercially available products. When the methacrylates are packaged in the presence of stabilizers, as is the case with most commercial methacrylates, they are generally used after removing the stabilizer (which can be carried out in a well-known manner by distillation or treatment on an alumina column).

[0105] Preferably, step b) is carried out in an aliphatic hydrocarbon solvent (e.g. methylcyclohexane). Advantageously, it is carried out in the reaction medium produced in step a). It is usually carried out in its reaction medium by adding methacrylate to the reaction product of step a) under stirring.

[0106] Prior to the addition of the methacrylate, the reactor is preferably degassed and inertized. Degassing the reactor removes residual gaseous monomers and also facilitates the addition of the methacrylate to the reactor. Making the reactor inert (e.g., with nitrogen) helps prevent the deactivation of carbon-metal bonds present in the reaction medium and necessary for the functionalization reaction of the copolymer. The added methacrylate can be pure or diluted with a hydrocarbon solvent, preferably with an aliphatic hydrocarbon solvent (e.g., methylcyclohexane). The methacrylate is kept in contact with the reaction product in step a) for the time required for the functionalization reaction of the copolymer chain ends. The functionalization reaction can usually be monitored by chromatographic analysis to monitor the consumption of methacrylate. The functionalization reaction is preferably carried out at a temperature ranging from 23° C. to 120° C., under stirring, for 1 minute to 60 minutes. The functionalization reaction is preferably carried out in an excess of the moles of methacrylate relative to the moles of neodymium and magnesium. In order to achieve almost quantitative functionalization, the molar ratio of the moles of methacrylate to the moles of neodymium and magnesium is greater than 2, particularly greater than 4. The molar ratio between the moles of methacrylate and the moles of neodymium and magnesium preferably ranges from 4 to 50, more preferably from 4 to 10.

[0107] Once the chain ends have been modified, step b) is followed by step c).

[0108] Step c), i.e. the chain termination reaction, is generally a reaction to deactivate the reactive sites still present in the reaction medium produced in step b). In step c), the chain termination reagent is brought into contact with the reaction product of step b) (generally in the reaction medium), for example by adding the termination reagent to the reaction medium produced in step b) or pouring the reaction medium obtained at the end of step b) into a solution containing the termination reagent. The termination reagent is generally added in excess relative to the number of carbon-metal bonds (such as C-Mg and C-Nd) present in the reaction medium. The termination reagent is generally a protic compound, a compound containing relatively acidic protons. Termination reagents include water, carboxylic acids (especially C 2 -C 18 fatty acids, such as acetic acid or stearic acid), aliphatic or aromatic alcohols (such as methanol, ethanol or isopropanol), or phenolic antioxidants.

[0109] After reaction with the protic compound, this process leads to a highly saturated diene elastomer carrying a tertiary amine function at one of its chain ends.

[0110] The highly saturated diene elastomer carrying a tertiary amine function at one of its chain ends can be separated from the reaction medium of step c) by methods known to those skilled in the art, for example by evaporating the solvent under reduced pressure or by a steam stripping operation.

[0111] Preferably, the rubber composition contains more than 50 phr of highly saturated diene elastomers useful for the purposes of the present invention, more preferably at least 80 phr of highly saturated diene elastomers useful for the purposes of the present invention. The remainder of 100 phr may consist entirely or partly of diene and ethylene elastomers in which the compounds of formula —CH —, useful for the purposes of the present invention as described in the present patent application, are absent. 2 -CH(CH 3 )-COOZ functional groups. The rubber composition may also comprise an elastomer selected from the group consisting of polybutadiene, polyisoprene, butadiene copolymers, isoprene copolymers and mixtures thereof, diene elastomers. The content of highly saturated diene elastomer useful for the purposes of the present invention is advantageously 100 phr. The highly saturated diene elastomer useful for the purposes of the present invention may consist of a mixture of highly saturated diene elastomers useful for the purposes of the present invention that differ from one another in microstructure or macrostructure.

[0112] The rubber composition is also essentially characterized by containing a reinforcing filler comprising silica or carbon black.

[0113] The silica used may be any reinforced silica known to those skilled in the art, especially one having a BET specific surface area and a CTAB specific surface area of ​​less than 450 m 2 / g, preferably 30m 2 / g to 400m 2 / g, especially at 60m 2 / g to 300m 2 / g. Examples of highly dispersible precipitated silicas ("HDS") include Ultrasil 7000 and Ultrasil 7005 silicas from Degussa, Zeosil 1165MP, 1135MP and 1115MP silicas from Rhodia, Hi-Sil EZ150G silica from PPG, Zeopol 8715, 8745 and 8755 silicas from Huber or silicas with a high specific surface area as described in application WO 03 / 016387.

[0114] In the present disclosure, 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" (Volume 60, page 309, February 1938), more specifically according to the French standard NF ISO 9277 of December 1996 [multipoint volumetric method (5 points) - gas: nitrogen - degassing: 160°C for 1 hour - relative pressure p / p 0 The CTAB specific surface area is the external surface area measured according to the French standard NF T 45-007 of November 1987 (method B).

[0115] The physical state in which the silica is provided is not important, whether it is in the form of powder, microspheres, granules or beads. Of course, silica is also understood to mean mixtures of different reinforcing silicas, in particular mixtures of highly dispersible silicas as described above.

[0116] A person skilled in the art will understand that a reinforcing filler of another nature, especially organic nature, such as carbon black, can be used as a filler equivalent to the silica described in this section, provided that the reinforcing filler is covered with a silica layer or contains functional sites, especially hydroxyl sites, on its surface that require the use of a coupling agent to establish a bond between the filler and the elastomer. Examples include carbon blacks for tires, such as described, for example, in patent documents WO 96 / 37547 and WO 99 / 28380.

[0117] All carbon blacks, in particular blacks of the HAF, ISAF, SAF, FF, FEF, GPF and SRF types conventionally used in rubber compositions for tires ("tire-grade" carbon blacks) are suitable as carbon blacks. These carbon blacks can be used alone as commercially available or in any other form (for example as a carrier for some of the rubber additives used).

[0118] According to one embodiment of the invention, the reinforcing filler comprises a mixture of silica and carbon black. When the rubber composition contains a mixture of silica and carbon black, the carbon black is preferably used in an amount of less than 20 phr, more preferably less than 10 phr (e.g., between 0.5 phr and 20 phr, especially between 2 phr and 10 phr). Within the specified interval, the coloring properties (black coloring agent) and UV stability of the carbon black are benefited without adversely affecting the typical performance qualities contributed by silica.

[0119] According to a most particularly preferred embodiment of the invention, the reinforcing filler contains more than 50% by mass of silica. More preferably, the reinforcing filler contains more than 50% by mass of silica and contains carbon black in an amount less than or equal to 5 phr.

[0120] To couple the silica to the elastomer, at least difunctional coupling agents (or binders), especially silanes, are used in a known manner, which are intended to ensure a satisfactory connection between the silica (its particle surface) and the elastomer. In particular, at least difunctional organosilanes or polyorganosiloxanes are used.

[0121] Use is made in particular of silane polysulfides which, depending on their specific structure, are referred to as “symmetrical” or “asymmetrical”, as described, for example, in applications WO 03 / 002648 (or US 2005 / 016651) and WO 03 / 002649 (or US 2005 / 016650).

[0122] Particularly suitable, without being restricted by the following definition, are silane polysulfides corresponding to the general formula (III):

[0123] JGS x -GJ(III)

[0124] in

[0125] -x is an integer from 2 to 8 (preferably from 2 to 5);

[0126] - Symbols G are the same or different and represent a divalent hydrocarbon group (preferably C 1 -C 18 Alkylene or C 6 -C 12 Arylene, more particularly C 1-C 10 Alkylene, especially C 1 -C 4 Alkylene, especially propylene);

[0127] - Symbol J, the same or different, corresponds to one of the following three formulas:

[0128]

[0129] in:

[0130] -Group R 1 , substituted or unsubstituted, identical or different from each other, represents C 1 -C 18 Alkyl, C 5 -C 18 Cycloalkyl or C 6 -C 18 Aryl (preferably C 1 -C 6 Alkyl, cyclohexyl or phenyl, especially C 1 -C 4 alkyl, more particularly methyl and / or ethyl),

[0131] -Group R 2 , substituted or unsubstituted, identical or different from each other, represents C 1 -C 18 Alkoxy or C 5 -C 18 Cycloalkoxy (preferably selected from C 1 -C 8 Alkoxy or C 5 -C 8 The cycloalkoxy group is even more preferably selected from C 1 -C 4 alkoxy groups, in particular methoxy and / or ethoxy).

[0132] In the case of mixtures of alkoxysilane polysulfides corresponding to the above formula (I), in particular the conventional commercially available mixtures, the average value of "x" is preferably a fraction between 2 and 5, more preferably a fraction close to 4. However, the invention can also be advantageously carried out using, for example, alkoxysilane disulfides (x=2).

[0133] Examples of silane polysulfides more particularly include bis((C 1 -C 4 ) alkoxy (C 1 -C 4 )alkylsilyl(C 1 -C 4)alkyl) polysulfides (especially disulfides, trisulfides or tetrasulfides), such as, for example, bis(3-trimethoxysilylpropyl) or bis(3-triethoxysilylpropyl) polysulfides. Among these compounds, bis(3-triethoxysilylpropyl) tetrasulfide (abbreviated to TESPT, formula [(C 2 H 5 O) 3 Si(CH 2 ) 3 S 2 ] 2 ) or bis(triethoxysilylpropyl) disulfide (abbreviated as TESPD, with the formula [(C 2 H 5 O) 3 Si(CH 2 ) 3 S] 2 ).

[0134] Coupling agents other than alkoxysilane polysulfides include in particular difunctional POS (polyorganosiloxanes), or hydroxysilane polysulfides as described in patent applications WO 02 / 30939 (or US 6774255) and WO 02 / 31041 (or US 2004 / 051210), or silanes or POS carrying azodicarbonyl functions as described, for example, in patent applications WO 2006 / 125532, WO 2006 / 125533 and WO 2006 / 125534.

[0135] The content of coupling agent is advantageously less than 30 phr, it being understood that it is generally desirable to use as little coupling agent as possible. Typically, the content of coupling agent is from 0.5 to 15% by weight relative to the amount of silica. Its content is preferably between 0.5 and 16 phr, more preferably in the range of 3 to 10 phr. It is easy for a person skilled in the art to adjust this content according to the content of silica used in the composition.

[0136] Preferably, the total content of reinforcing filler (whether silica or carbon black or a mixture thereof) is between 30 and 200 phr, more preferably between 40 and 160 phr. Any of these ranges for the total content of reinforcing filler can be applied to any embodiment of the present invention.

[0137] In addition to the coupling agents, the rubber composition according to the invention may also contain coupling activators, agents for coating the inorganic fillers or, more generally, processing aids capable of improving the processability in the uncured state in a known manner by improving the dispersion of the filler in the rubber matrix and reducing the viscosity of the composition.

[0138] Another basic feature of the rubber composition is to contain a crosslinking system. Chemical crosslinking allows the formation of covalent bonds between the elastomer chains. The crosslinking system can be a vulcanization system or one or more peroxide compounds. According to any embodiment of the present invention, the crosslinking system is preferably a vulcanization system.

[0139] The vulcanization system itself is based on sulfur (or sulfur donor) and a primary vulcanization accelerator. In addition to this basic vulcanization system, various known secondary vulcanization accelerators or vulcanization activators are introduced during the first non-production phase and / or during the production phase as described later, such as zinc oxide, stearic acid or equivalent compounds, or guanidine derivatives (especially diphenylguanidine). Sulfur is preferably used in a content of 0.5phr to 12phr, especially 1phr to 10phr. The primary vulcanization accelerator is preferably used in a content between 0.5phr and 10phr, more preferably between 0.5phr and 5phr. The accelerator used (primary or secondary) can be any compound that can be used as a vulcanization accelerator for diene elastomers in the presence of sulfur, especially thiazole-type accelerators and derivatives thereof, or thiuram-type or zinc dithiocarbamate-type accelerators. It is preferred to use a sulfonamide-type primary accelerator.

[0140] When one or more peroxide compounds are used for chemical crosslinking, the one or more peroxide compounds preferably account for 0.01 to 10 phr. Peroxide compounds that can be used as chemical crosslinking systems include acyl peroxides such as benzoyl peroxide or p-chlorobenzoyl peroxide, ketone peroxides such as methyl ethyl ketone peroxide, peroxyesters such as tert-butyl peroxyacetate, tert-butyl peroxybenzoate and tert-butyl peroxyphthalate, alkyl peroxides such as diisopropyl peroxide, di(tert-butyl) peroxybenzoate and 1,3-bis(tert-butylperoxyisopropyl)benzene, or hydroperoxides such as tert-butyl hydroperoxide.

[0141] The rubber composition according to the invention may also contain some or all of the customary additives usually used in elastomeric compositions intended to constitute the external mix of a finished rubber article (for example a tire, in particular a tread), such as, for example, plasticizers or extender oils, whether these are hydrocarbon plasticizing resins of an aromatic or non-aromatic nature, especially very weakly aromatic or non-aromatic oils (for example paraffin oils or hydrogenated naphthenic oils, MES oils or TDAE oils), vegetable oils, in particular glycerides such as triolein, pigments, protective agents such as antiozonant waxes, chemical antiozonants or antioxidants.

[0142] The rubber composition according to the invention can be produced in a suitable mixer according to the general procedures well known to those skilled in the art, by adopting two consecutive preparation stages: a first stage of thermomechanical processing or kneading at high temperature (up to a maximum temperature between 130° C. and 200° C., preferably between 145° C. and 185° C.) (sometimes called the “non-productive” stage), followed by a second stage of mechanical processing at a lower temperature, generally below 120° C., for example between 60° C. and 100° C. (sometimes called the “productive” stage), during which finishing stage a chemical crosslinking agent, in particular a vulcanization system, is incorporated.

[0143] Generally, all the essential components of the composition that the tyre of the invention comprises, with the exception of the crosslinking system, namely the reinforcing inorganic filler and, where appropriate, the coupling agent, are intimately incorporated into the elastomer by kneading during a first ("non-productive") stage, i.e. at least these various essential components are introduced into a mixer and subjected to thermomechanical kneading in one or more steps until a maximum temperature of between 130° C. and 200° C., preferably between 145° C. and 185° C., is reached.

[0144] By way of example, the first phase (non-productive phase) is carried out in a single thermomechanical step, during which all the necessary components, except the chemical crosslinking agent, the optional additional processing aids and various other additives are introduced into a suitable mixer (e.g. a standard internal mixer). The total duration of kneading in this non-productive phase is preferably between 1 and 15 minutes. After cooling the mixture thus obtained during the first (non-productive) phase, the crosslinking system is then generally incorporated into an open mixer (e.g. an open mill) at low temperature; everything is then mixed (productive phase) for a few minutes, for example between 2 and 15 minutes.

[0145] The final composition thus obtained is subsequently calendered, for example, in the form of sheets or plates, especially for laboratory characterizations, or extruded into rubber moldings which can be used as semi-finished tires for vehicles.

[0146] Thus, according to a particular embodiment of the invention, the rubber composition according to the invention, which may be in the uncured state (before crosslinking or vulcanization) or in the cured state (after crosslinking or vulcanization), is a semi-finished product that can be used in tires, in particular in tire treads.

[0147] In summary, the present invention is advantageously implemented according to any one of the following embodiments 1 to 25:

[0148] Embodiment 1: A rubber composition comprising a highly saturated diene elastomer containing 1,3-diene units and more than 50 mol % of ethylene units and carrying at one of its chain ends a radical of the formula -CH2 -CH(CH 3 )-COOZ, Z is a hydrocarbon group substituted by a tertiary amine functional group, the reinforcing filler includes silica or carbon black, and the highly saturated diene elastomer is a copolymer of ethylene and 1,3-diene or a copolymer of ethylene, 1,3-diene and α-monoolefin.

[0149] Embodiment 2: The rubber composition according to Embodiment 1, wherein Z represents a saturated acyclic hydrocarbon group substituted with a tertiary amine functional group.

[0150] Embodiment 3: The rubber composition according to Embodiment 2, wherein the saturated acyclic hydrocarbon group substituted with the tertiary amine functional group is an alkyl group having 1 to 3 carbon atoms.

[0151] Embodiment 4: The rubber composition according to any one of Embodiments 1 to 3, wherein the tertiary amine functional group is an N,N-dialkylamino group.

[0152] Embodiment 5: The rubber composition according to Embodiment 4, wherein the alkyl groups substituting the nitrogen atoms each have 1 to 3 carbon atoms.

[0153] Embodiment 6: The rubber composition according to Embodiment 4 or 5, wherein the alkyl groups substituting the nitrogen atoms each have 1 carbon atom or 2 carbon atoms.

[0154] Embodiment 7: The rubber composition according to any one of Embodiments 1 to 6, wherein Z represents N,N-di(C 1 -C 3 ) alkylamino (C 1 -C 3 )alkyl.

[0155] Embodiment 8: The rubber composition according to any one of Embodiments 1 to 7, wherein Z represents 2-(N,N-dimethylamino)ethyl, 2-(N,N-diethylamino)ethyl or 2-(N,N-diisopropylamino)ethyl, more preferably 2-(N,N-dimethylamino)ethyl.

[0156] Embodiment 9: The rubber composition according to any one of Embodiments 1 to 8, wherein the copolymer is a copolymer of ethylene and 1,3-diene.

[0157] Embodiment 10: The rubber composition according to any one of Embodiments 1 to 9, wherein the ethylene units in the highly saturated diene elastomer represent at least 60 mol % of all the monomer units in the highly saturated diene elastomer.

[0158] Embodiment 11: The rubber composition according to any one of Embodiments 1 to 10, wherein the ethylene units in the highly saturated diene elastomer represent at least 65 mol % of all the monomer units in the highly saturated diene elastomer.

[0159] Embodiment 12: The rubber composition according to any one of Embodiments 1 to 11, wherein the ethylene units in the highly saturated diene elastomer represent at least 70 mol % of all monomer units in the highly saturated diene elastomer.

[0160] Embodiment 13: The rubber composition according to any one of Embodiments 1 to 12, wherein the ethylene units in the highly saturated diene elastomer represent less than 90 mol % of all monomer units in the highly saturated diene elastomer.

[0161] Embodiment 14: The rubber composition according to any one of Embodiments 1 to 13, wherein the ethylene units in the highly saturated diene elastomer represent at most 85 mol % of all the monomer units in the highly saturated diene elastomer.

[0162] Embodiment 15: The rubber composition according to any one of Embodiments 1 to 14, wherein the ethylene units in the highly saturated diene elastomer represent at most 80 mol % of all the monomer units in the highly saturated diene elastomer.

[0163] Embodiment 16: The rubber composition of any one of Embodiments 1 to 15, wherein the 1,3-diene is 1,3-butadiene, isoprene, myrcene, β-farnesene, or a mixture thereof.

[0164] Embodiment 17: The rubber composition according to any one of Embodiments 1 to 16, wherein the 1,3-diene is 1,3-butadiene or a mixture of 1,3-butadiene and myrcene or a mixture of 1,3-butadiene and β-farnesene.

[0165] Embodiment 18: The rubber composition according to any one of Embodiments 1 to 17, wherein the copolymer contains 1,2-cyclohexane units of formula (I)

[0166]

[0167] Embodiment 19: The rubber composition according to embodiment 18, wherein the highly saturated diene elastomer contains up to 15 mol % of 1,2-cyclohexane units of formula (I), this percentage being expressed relative to all the monomer units in the highly saturated diene elastomer.

[0168] Embodiment 20: The rubber composition according to any one of Embodiments 1 to 19, wherein the α-monoolefin is styrene.

[0169] Embodiment 21: The rubber composition of any one of Embodiments 1 to 20, wherein the highly saturated diene elastomer is a statistical copolymer.

[0170] Embodiment 22: The rubber composition according to any one of Embodiments 1 to 21, wherein the reinforcing filler contains greater than 50% by mass of silica.

[0171] Embodiment 23: The rubber composition according to any one of Embodiments 1 to 22, wherein the crosslinking system is a vulcanization system.

[0172] Embodiment 24: A tire comprising a tread, the tire comprising the rubber composition defined in any one of Embodiments 1 to 23.

[0173] Embodiment 25: The tire of Embodiment 24, comprising the rubber composition in a tread of the tire.

[0174] The above mentioned and other characteristics of the invention will be more clearly understood on reading the following description of an embodiment of the invention given by way of illustration and not limitation.

[0175] Example

[0176] Nuclear Magnetic Resonance (NMR):

[0177] pass 1 H. 13 C and 29 Si NMR spectroscopy was used to characterize the functionalized products of the copolymers. NMR spectra were recorded on a Bruker Avance III HD 500 MHz spectrometer equipped with a BBFO Z-stage 5 mm "broadband" cryoprobe. 1 Quantitative H NMR experiments used a 30° simple pulse sequence with a 5 s repetition time between acquisitions. Between 64 and 256 accumulations were performed. 13 C NMR quantitative experiments used a 30° simple pulse sequence with proton decoupling and a repetition time of 10 seconds between each acquisition. Accumulations of 1024 to 10240 were performed. 1 H / 13 C 2D experiments to determine the structure of the functionalized polymer. 1 The axis of the H chemical shift is relative to the solvent (CDCl 3 ) in δ 1H =7.20 ppm for calibration with protonated impurities. 13The axis of the C chemical shift is relative to the solvent (CDCl 3 ) in δ 13C =77ppm for calibration.

[0178] The chemical structure of each functional polymer was determined by NMR ( 1 H. 13 C) Identification.

[0179] 3D-SEC analysis:

[0180] In order to determine the number-average molar mass (Mn) and, where appropriate, the weight-average molar mass (Mw) and the polydispersity index (PI, also denoted ), use the following method.

[0181] The number average molar mass (Mn), weight average molar mass (Mw) and polydispersity index of the polymers (hereinafter samples) were determined absolutely by triple-detection size exclusion chromatography (SEC). The advantage of triple-detection size exclusion chromatography is that the average molar mass can be measured directly without calibration.

[0182] The value of the refractive index increment dn / dc of the sample solution is measured online using the peak area detected by the refractometer (RI) of the liquid chromatography equipment. In order to use this method, it is necessary to check that 100% of the sample mass is injected and eluted through the column. The area of ​​the RI peak depends on the concentration of the sample, the constant of the RI detector and the value of dn / dc.

[0183] The average molar mass is determined using a 1 g / l previously prepared and filtered tetrahydrofuran solution which is injected into the chromatographic line. The apparatus used is a Wyatt chromatographic line. The elution solvent is tetrahydrofuran containing 250 ppm BHT (2,6-di(tert-butyl)-4-hydroxytoluene) at a flow rate of 1 mL.min -1 , the system temperature was 35°C, and the analysis time was 60 minutes. The chromatographic columns used were a set of three Agilent chromatographic columns with the trade name PL Gel Mixed B LS. The volume of the injected sample solution was 100 μl. The detection system consisted of a Wyatt differential viscometer with the trade name Viscostar II, a Wyatt differential refractometer with the trade name OptilabT-Rex at a wavelength of 658 nm, and a Wyatt multi-angle static light scattering detector with a wavelength of 658 nm and the trade name Dawn Heleos 8+.

[0184] By integrating the values ​​of the refractive index increment dn / dc of the sample solution obtained above, the number average molar mass and the polydispersity index were calculated. The software used for processing the chromatographic data was the Astra system from Wyatt.

[0185] Determination of glass transition temperature of polymers:

[0186] The glass transition temperature is measured using a differential scanning calorimeter according to standard ASTM D3418 (1999).

[0187] Kinetic properties:

[0188] The dynamic properties are measured on a viscosity analyzer (Metravib VA4000) according to standard ASTM D 5992-96. The dynamic properties are recorded on a sample of the vulcanized composition (thickness 4 mm and cross-sectional area 400 mm) subjected to a simple alternating sinusoidal shear stress at a frequency of 10 Hz under standard temperature conditions (23° C.) according to standard ASTM D 1349-99. 2 The response of the rubber composition (cylindrical test specimen) is measured. The strain amplitude sweep is performed from 0.1% to 50% (outward cycle) and then from 50% to 0.1% (return cycle). The result adopted is the loss factor tan(δ). For the return cycle, the maximum value tan(δ) observed is recorded, denoted tan(δ)max. The values ​​of tan(δ)max are given in base 100, with the value 100 being assigned to the control composition (T). The lower the value of tan(δ)max, the lower the hysteresis of the rubber composition.

[0189] Preparation of elastomers:

[0190] The metallocene [{Me 2 SiFlu 2 Nd(μ-BH 4 ) 2 Li(THF)}] 2 .

[0191] Butyloctylmagnesium BOMAG (20% in heptane, 0.88 mol.l -1 ) was obtained from Chemtura and stored in a Schlenk tube under an inert atmosphere.

[0192] N35 grade ethylene was obtained from Air Liquide and used without prior purification.

[0193] 1,3-Butadiene and myrcene were purified through an alumina protection tube.

[0194] The functionalizing agent used was ethyl 2-(dimethylamino)methacrylate from Sigma-Aldrich. The commercial methacrylate was used after being purified by passing through an alumina protection tube and sparged with nitrogen.

[0195] Methylcyclohexane (MCH) solvent from BioSolve was dried and purified on an alumina column in a solvent purifier from mBraun and used under an inert atmosphere.

[0196] All reactions were carried out under an inert atmosphere.

[0197] Synthesis of non-functionalized copolymers of ethylene, 1,3-butadiene and myrcene: Elastomer E1:

[0198] 64 L of a solution of MCH and BOMAG (23 mmol) in MCH (0.01 mol / L) were introduced into a 90 L stainless steel reactor. The reactor was heated to 80°C and the monomers were added at a controlled rate to keep the composition of the monomer mixture in the polymerization medium constant. The ethylene flow rate was set to 40 g / min; myrcene and butadiene were injected independently, with the flow rates controlled by the ethylene flow rate according to a myrcene / ethylene weight ratio of 1.62 and according to a butadiene / ethylene weight ratio of 0.25. When the reactor pressure reached 8 bar, a preformed catalytic system (6.25 mmol Nd) prepared according to the protocol at a concentration of 0.007 mol / L was introduced into the polymerization medium. When 5 to 6 kg of polymer were formed, a chain termination reaction was carried out by quenching with methanol: the polymer was recovered after the stripping step. The polymer was then dried at 150°C on a single screw worm turbine.

[0199] The catalytic system is a preformed catalytic system. The catalytic system consists of a metallocene [Me 2 Si(Flu) 2 Nd(μ-BH 4 ) 2 Li(THF)], a cocatalyst (butyloctyl magnesium (BOMAG) and a preformed monomer (1,3-butadiene) were prepared in methylcyclohexane. The catalytic system was prepared according to the preparation method of Section II.1 of patent application WO 2017 / 093654A1.

[0200] 5.7 mL of a solution of butyloctyl magnesium in heptane (0.88 M, 5.0 mmol) and 1.462 g of the complex {(Me 2 Si(C 13 H 8 ) 2 )Nd(μ-BH 4 ) 2 Li(THF)} 2(Nd mole number, nNd = 2.3 mmol) (complex 1) was introduced into a 500 mL steinie bottle containing 380 mL methylcyclohexane which had been degassed with nitrogen in advance. 17 mL of 1,3-butadiene (hereinafter also referred to as butadiene) was added to the steinie bottle at 17°C. The contents of the steinie bottle were then heated to 80°C and stirred for 4 hours. The resulting catalyst solution was stored in a freezer at -25°C.

[0201] Synthesis of functionalized copolymers of ethylene, 1,3-butadiene and myrcene: Elastomer E2:

[0202] Functional elastomers were prepared under the same synthetic conditions as their non-functional homologues, except that the chain termination reaction was replaced by a functionalization reaction as described in the Functionalization Procedure below.

[0203] Functionalization procedure:

[0204] When the desired monomer conversion is reached (5 to 6 kg of polymer), the contents of the reactor are degassed and the functionalizing agent methacrylate is introduced into the polymerization medium under an inert atmosphere by overpressure in a ratio of 40 equivalents relative to the moles of Nd and Mg introduced into the reactor. The reaction medium is stirred at 80° C. for 15 minutes. The reaction medium is deactivated with methanol. After the stripping step, the polymer is recovered. The polymer is then dried on a single screw worm turbine at 150° C. It is then purified by SEC (THF) and 1 H and 13 C NMR analysis.

[0205] The properties of the prepared elastomers are shown in Table 1. SEC and NMR analysis confirmed that the chain ends of elastomer E2 were functionalized with only one methacrylate monomer unit bearing an amine function.

[0206] Table 1

[0207]

[0208] (1) 1,2-cyclohexane ring unit of formula (I)

[0209] Preparation of rubber composition:

[0210] The rubber compositions (whose formulations, expressed in phr (parts by weight per hundred parts by weight of elastomer) are shown in Table 2) were prepared according to the following procedure: elastomer, silica, coupling agent and various other ingredients except the vulcanizing system were continuously introduced into an 85 cm 3The mixture is then subjected to a thermomechanical treatment (non-production phase) in a step of about 5 min for a total duration until a maximum discharge temperature of 160 ° C is reached. The mixture thus obtained is recovered and cooled, and then sulfur and accelerators are incorporated into a mixer (homogenizer) at 25 ° C, and all materials are mixed (production phase) for about ten minutes. The composition thus obtained is then calendered into the form of a rubber sheet (thickness of 2 mm to 3 mm) or a rubber sheet for measuring physical properties or mechanical properties after vulcanization at 150 ° C.

[0211] The rubber composition C1 contains a highly saturated diene elastomer with methacrylate monomer units at the chain ends (elastomer E2). It is in accordance with the invention. The rubber composition T1 contains an unfunctionalized highly saturated diene elastomer E1. It is synthesized according to the same procedure as the elastomer E2, except that no functionalizing agent is added, the process being carried out directly after degassing the reactor, with the step of precipitation from the reaction medium methanol.

[0212] The results are shown in Table 3.

[0213] The rubber composition C1 exhibits a lower hysteresis than its reference composition T1. This reduction in hysteresis is attributed to the functionalization of the chain ends of the highly saturated diene elastomer with a single methacrylate monomer unit bearing a tertiary amine function, since this result is obtained without modification of the elastomer by methacrylate and without the formation of polymethacrylate blocks (the formation of which leads to a change in the glass transition temperature of the rubber composition), thus modifying certain properties of the rubber composition, such as rheological properties and in particular stiffness.

[0214] Table 2

[0215] Composition (in phr) T1 C1 Elastomer E1 100 Elastomer E2 100 Silica (1) 70 70 Carbon Black(2) 2 2 Coupling agent (3) 7 7 DPG(4) 1.2 1.2 Ozone wax(5) 2.5 2.5 Antioxidants (6) 3.8 3.8 Antioxidants (7) 1.6 1.6 Stearic acid(8) 3 3 ZnO(9) 0.9 0.9 sulfur 0.9 0.9 CBS(10) 2.3 2.3

[0216] (1) Zeosil 1165MP in microbead form from Solvay-Rhodia

[0217] (2)N234

[0218] (3) Liquid silane (TESPT) Si69 from Evonik

[0219] (4) Diphenylguanidine, Perkacit DPG from Flexsys

[0220] (5) Ozone-resistant wax, Varazon 4959 from Sasol Wax

[0221] (6) N-(1,3-Dimethylbutyl)-N'-phenyl-p-phenylenediamine, Santoflex 6PPD from Flexsys

[0222] (7) Tetramethylquinone

[0223] (8) Stearic acid, Pristerene 4931 from Uniqema

[0224] (9) Industrial grade zinc oxide from Umicore

[0225] (10) N-cyclohexyl-2-benzothiazolesulfonamide, Santocure CBS from Flexsys Table 3

[0226] Composition T1 C1 tan(δ)max at 23℃ 100 90

Claims

1. A rubber composition comprising a highly saturated diene elastomer containing 1,3-diene units and more than 50 mol % of ethylene units and having at one of its chain ends a residue of the formula -CH 2 -CH(CH 3 )-COOZ, Z is a hydrocarbon group substituted by a tertiary amine functional group, the reinforcing filler includes silica or carbon black, and the highly saturated diene elastomer is a copolymer of ethylene and 1,3-diene or a copolymer of ethylene, 1,3-diene and α-monoolefin.

2. The rubber composition according to claim 1, in, Z represents a saturated acyclic hydrocarbon group substituted with a tertiary amine functional group.

3. The rubber composition according to claim 2, in, The saturated acyclic hydrocarbon group substituted by the tertiary amine functional group is an alkyl group having 1 to 3 carbon atoms.

4. The rubber composition according to any one of claims 1 to 3, in, The tertiary amine functional group is N,N-dialkylamino.

5. The rubber composition according to claim 4, in, The alkyl groups substituting the nitrogen atom each have 1 to 3 carbon atoms, preferably 1 carbon atom or 2 carbon atoms.

6. The rubber composition according to any one of claims 1 to 5, in, Z represents N,N-di(C 1 -C 3 ) alkylamino (C 1 -C 3 )alkyl, preferably 2-(N,N-dimethylamino)ethyl, 2-(N,N-diethylamino)ethyl or 2-(N,N-diisopropylamino)ethyl, more preferably 2-(N,N-dimethylamino)ethyl.

7. The rubber composition according to any one of claims 1 to 6, in, The copolymer is a copolymer of ethylene and 1,3-diene.

8. The rubber composition according to any one of claims 1 to 7, in, The ethylene units in the highly saturated diene elastomer represent less than 90 mol % of all the monomer units in the highly saturated diene elastomer.

9. The rubber composition according to any one of claims 1 to 8, in, The 1,3-diene is 1,3-butadiene, isoprene, myrcene, β-farnesene or a mixture thereof.

10. The rubber composition according to any one of claims 1 to 9, in, The 1,3-diene is 1,3-butadiene or a mixture of 1,3-butadiene and myrcene or a mixture of 1,3-butadiene and β-farnesene.

11. The rubber composition according to any one of claims 1 to 10, in, The copolymer contains 1,2-cyclohexane units of formula (I):

12. The rubber composition according to any one of claims 1 to 11, in, The highly saturated diene elastomer is a statistical copolymer.

13. The rubber composition according to any one of claims 1 to 12, in, The reinforcing filler contains more than 50% by mass of silica.

14. A tyre comprising a tread, said tyre comprising the rubber composition as defined in any one of claims 1 to 13, preferably comprising said rubber composition in the tread of said tyre.

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