Triblock polymer having two terminal blocks of polystyrene and polyvinylpyridine, respectively, and a random copolymer elastomer of ethylene and 1,3-dienes as the central block

Abstract

The invention relates to a triblock polymer of formula A-B-C in which the symbols A, B and C represent a polystyrene block, an elastomer block and a polyvinylpyridine block, respectively, the styrene units of block A being present in the triblock polymer at a molar content of less than 15% of the constituent repeating units of the triblock polymer, the elastomer block being a random copolymer of ethylene, a first 1,3-diene and a second 1,3-diene, the first 1,3-diene being 1,3-butadiene or isoprene, the second 1,3-diene being a 1,3-diene of formula CH2=CR'-CH=CH2, the symbol R' representing a hydrocarbon chain having 3 to 20 carbon atoms, the vinylpyridine units of block C being present in the triblock polymer at a molar content of less than 5% of the constituent repeating units of the triblock polymer.

Description

[0001] Triblock polymer having two terminal blocks, respectively polystyrene and polyvinylpyridine, and as a central block a statistical copolymer elastomer of ethylene and 1,3-dienes

[0002] The field of the present invention is that of copolymers containing ethylene units and 1,3-diene units.

[0003] The Applicant described statistical copolymers of ethylene and myrcene or of p-famesene and 1,3-butadiene, and their use in tire rubber compositions, in patent applications WO 2021053051 A1 and WO 2022189718 A1. These statistical copolymers, compared to statistical copolymers of ethylene and 1,3-butadiene, provide a rubber composition with a better compromise between stiffness, hysteresis, and curing properties. To meet certain tire applications, it may be necessary to improve dry grip performance. To address this need, manufacturers seek to increase the high-temperature hysteresis (100°C) of the rubber compositions used in tire treads.

[0004] The inventors discovered that replacing in a rubber composition an elastomer which is a statistical copolymer of ethylene, a 1,3-diene which is 1,3-butadiene or isoprene and a branched 1,3-diene of formula CH2=CR'-CH=CH2, the symbol R' representing a hydrocarbon chain having 3 to 20 carbon atoms with a triblock polymer having as its central block the statistical copolymer and two terminal blocks, one a polystyrene, the other a polyvinylpyridine in given molar proportions, makes it possible to significantly increase the high temperature hysteretic potential, 100°C, of ​​the rubber composition.

[0005] Thus, a first object of the invention is a triblock polymer of formula ABC in which the symbol A represents a polystyrene block, the symbol B represents an elastomer block and the symbol C represents a polyvinylpyridine block,

[0006] the styrene units of block A being present in the triblock polymer at a molar content of less than 15% of the repeating motifs constituting the triblock polymer,

[0007] the elastomer block being a statistical copolymer of ethylene, a first 1,3-diene and a second 1,3-diene, the first 1,3-diene being 1,3-butadiene or isoprene, the second 1,3-diene being a 1,3-diene of formula CH2=CR'-CH=CH2, the symbol R' representing a hydrocarbon chain having 3 to 20 carbon atoms,

[0008] the vinylpyridine units of block C being present in the triblock polymer in a molar content of less than 5% of the repeating motifs constituting the triblock polymer.

[0009] A second object of the invention is a rubber composition comprising a triblock polymer according to the invention, a reinforcing filler, and a crosslinking system. A third object of the invention is a tire comprising a tread, which tire includes a rubber composition according to the invention, preferably in its tread.

[0010] 2024PAT00265WO Another object of the invention is a process for synthesizing a triblock polymer of formula ABC, A representing a polystyrene block, B representing an elastomer block which is a statistical copolymer of ethylene, a first 1,3-diene and a second 1,3-diene, the first 1,3-diene being 1,3-butadiene or isoprene, the second 1,3-diene being a 1,3-diene of formula CH2=CR'-CH=CH2, the symbol R' representing a hydrocarbon chain having 3 to 20 carbon atoms, C representing a polyvinylpyridine block,

[0011] which process comprises, in the presence of a catalytic system based on at least one metallocene of formula (I) and an organomagnesium compound of formula (II), the statistical copolymerization of a monomer mixture of ethylene, the first 1,3-diene and the second 1,3-diene, followed by the homopolymerization of a vinylpyridine,

[0012] P(Cp 1 CP 2 ) Nd(BH4)(i +v ) Li v (THF)x (I)

[0013] R-Mg-A (II)

[0014] CP 1 and Cp 2 , identical or different, being chosen from the group consisting of cyclopentadienyl groups and fluorenyl groups, the groups being substituted or not, P being a group bridging the two Cp groups 1 and Cp 2 and representing a ZR group 1 R 2 Z represents a silicon or carbon atom, R 1 and R 2, identical or different, each representing an alkyl group comprising from 1 to 20 carbon atoms, preferably a methyl,

[0015] y, an integer, being equal to or greater than 0,

[0016] x, whether an integer or not, being equal to or greater than 0,

[0017] R comprising a benzene ring of which two carbon atoms are substituted, one of the two is substituted by a methyl, an ethyl or an isopropyl or forms a ring with the carbon atom which is its nearest neighbor, the second carbon atom being substituted by a methyl, an ethyl or an isopropyl, the magnesium atom being in ortho position with respect to each of said two carbon atoms,

[0018] the symbol A in formula (II) representing the polystyrene block constituting the triblock polymer.

[0019] Detailed description:

[0020] Any range of values ​​designated by the expression "between a and b" represents the range of values ​​greater than "a" and less than "b" (i.e., bounds a and b excluded) while any range of values ​​designated by the expression "from a to b" means the range of values ​​from "a" to "b" (i.e., including the strict bounds a and b).

[0021] The abbreviation "pce" means parts by weight per hundred parts of elastomer (of the total elastomers if more than one elastomer is present).

[0022] The compounds mentioned in the description can be of fossil origin or bio-based. In the latter case, they may be derived, partially or entirely, from biomass or obtained from renewable raw materials derived from biomass. Similarly, the compounds mentioned may also come from the recycling of previously used materials; that is, they may be derived, partially or entirely, from a process

[0023] 2024PAT00265WOde recycling, or obtained from raw materials themselves derived from a recycling process.

[0024] The block represented by the symbol B in the ABC formula, hereafter referred to as "block B," constitutes the central block of the triblock polymer. Block B is an elastomer block that is a statistical copolymer, meaning that the monomer units constituting block B are statistically distributed within block B. The two other blocks, represented by A and C, hereafter referred to as block A and block C, constitute the terminal blocks of the triblock polymer. Block A and block C are homopolymers, respectively a polystyrene and a polyvinylpyridine.

[0025] According to the invention, block B is a copolymer of ethylene, a first 1,3-diene and a second 1,3-diene, in which case the monomer units of block B are those resulting from the copolymerization of the only three monomers, namely ethylene, the first 1,3-diene and the second 1,3-diene.

[0026] An ethylene unit is known to be a unit with the repeating unit -(CH2-CH2)-. Block B preferably contains more than 50 mole percent of ethylene units. In this application, the percentage of ethylene units in block B, that is, the number of moles of ethylene units in block B, is expressed as a mole percentage relative to the number of repeating units constituting block B. More preferably, block B contains more than 60 mole percent of ethylene units. More preferably, block B contains at least 70 mole percent of ethylene units.

[0027] According to a particular embodiment of the invention, block B contains less than 90% by moles of ethylene units.

[0028] According to another particular embodiment of the invention, block B contains at most 85% by moles of ethylene units.

[0029] Preferably, block B contains less than 30 mole percent of the second 1,3-diene units. More preferably, block B contains at most 20 mole percent of the second 1,3-diene units. Even more preferably, block B contains at most 15 mole percent of the second 1,3-diene units. In this application, the percentage of second 1,3-diene units in block B, that is, the number of moles of second 1,3-diene units in block B, is expressed as a mole percentage relative to the number of repeating units constituting block B.

[0030] According to one embodiment, block B contains less than 30 mole percent of first 1,3-diene units. In the present application, the percentage of first 1,3-diene units in block B, namely the number of moles of first 1,3-diene units in block B, is expressed as a mole percentage relative to the number of repeating units constituting block B. Preferably, block B contains less than 20 mole percent of first 1,3-diene units.

[0031] According to one embodiment of the invention, block B contains from 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

[0032] 2024PAT00265WO1,3-diene. According to this embodiment of the invention, block B preferably contains less than 30% by mole of units of the first 1,3-diene, more preferably less than 20% by mole of units of the first 1,3-diene.

[0033] According to another embodiment of the invention, block B 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, block B preferably contains less than 20% by mole of units of the first 1,3-diene.

[0034] According to yet another embodiment of the invention, block B contains from 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, block B preferably contains less than 30% by mole of units of the first 1,3-diene, more preferably less than 20% by mole of units of the first 1,3-diene.

[0035] According to yet another embodiment of the invention, block B 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, block B preferably contains less than 20% by mole of units of the first 1,3-diene.

[0036] According to any one of the embodiments of the invention, block B preferably contains less than 80% by mole of ethylene units.

[0037] According to any one of the embodiments of the invention, block B preferably contains at least 1 mole percent of units of the second 1,3-diene, more preferably at least 5 mole percent of units of the second 1,3-diene.

[0038] According to the invention, "a second 1,3-diene" means one or more second 1,3-dienes. Suitable second 1,3-dienes include, for example, myrcene, p-farnesene, or a mixture thereof. The second 1,3-diene is preferably myrcene, p-farnesene, or a mixture of myrcene and p-famesene. Preferably, the expression "a second 1,3-diene" refers to a single compound, that is, a single second 1,3-diene. The second 1,3-diene is more preferably myrcene.

[0039] The second 1,3-diene can give rise to monomeric units of configuration 1,2 represented by formula (1), of configuration 3,4 represented by formula (2), and of configuration 1,4 whose trans form is represented below by formula (3). Preferably, the units of the second 1,3-diene in configuration 1,2 and the units of the second 1,3-diene in configuration 3,4 represent more than 50% by mole of the units of the second 1,3-diene. When block B contains units of the second 1,3-diene that are more than 50% by mole of the units of configuration 1,2 or 3,4, the complement to 100% of the units

[0040] 2024PAT00265WOdu second 1,3-diene is preferentially 1,4-trans configuration units.

[0041]

[0042] According to any one of the embodiments of the invention, block B preferably contains vinyl units, i.e. of configuration 1,2 and of configuration 3,4.

[0043] According to a particular embodiment of the invention, especially when the first 1,3-diene is 1,3-butadiene or a mixture of 1,3-butadiene and isoprene, block B further contains 1,2-cyclohexanediyl motifs. The 1,2-cyclohexanediyl motif has formula (II).

[0044]

[0045] (II)

[0046] The presence of these cyclic structures in block B results from a very specific insertion of ethylene and 1,3-butadiene during polymerization, as described, for example, in document WO 2007054224. The mechanism for obtaining such a microstructure is described, for example, in Macromolecules 2009, 42, 3774-3779. The content of 1,2-cyclohexanediyl motifs in block B varies according to the respective contents of ethylene and 1,3-butadiene in block B. Block B preferably contains less than 15 mol% of 1,2-cyclohexanediyl motif units. In the present application, the content of 1,2-cyclohexanediyl motifs in block B is expressed as a mole percentage relative to the number of repeating motifs constituting block B.

[0047] Preferably, block B has a glass transition temperature below -35°C, preferably between -70°C and -35°C. The glass transition temperature of block B can be adjusted, for example, by the chemical structure of the 1,3-dienes, using the respective proportions of units resulting from the copolymerization of the monomers constituting block B.

[0048] According to any one of the embodiments of the invention, the first 1,3-diene is preferably 1,3-butadiene.

[0049] Block B has a number-average molar mass, Mn, preferably greater than 100,000 g / mol. Block B has a number-average molar mass preferably less than 200,000 g / mol.

[0050] Advantageously, block B has a number-average molar mass ranging from more than 100,000 g / mol to less than 200,000 g / mol.

[0051] The block represented by the symbol A in formula ABC, and hereafter referred to as block A, has the essential characteristic of being a polystyrene. Preferably, block A represents linear polystyrene. Preferably, block A is atactic polystyrene.

[0052] The styrene units of block A are present in the triblock polymer at a molar content of less than 15% of the repeating units constituting the triblock polymer. With a molar content of styrene units of block A below 15%, the triblock polymer exhibits elastomeric properties. Above 15%, the polymer begins to lose its elastomeric properties, and the finishing steps become problematic. The styrene units of block A are present in the triblock polymer at a molar content preferably greater than 2% of the repeating units constituting the triblock polymer. Preferably, block A has a number-average molar mass greater than 3,000 g / mol and less than or equal to 30,000 g / mol.

[0053] The block represented by the symbol C in the ABC formula and hereafter referred to as block C has the essential characteristic of being a polyvinylpyridine. The vinylpyridine units of block C are present in the triblock polymer at a molar content of less than 5% of the repeating units constituting the triblock polymer. Vinylpyridine unit contents of block C greater than or equal to 5% lead to an increase in the rigidity of the triblock polymer, and the finishing steps become more difficult. The vinylpyridine units of block C are present in the triblock polymer at a molar content preferably greater than 0.1% of the repeating units constituting the triblock polymer. The vinylpyridine may be 4-vinylpyridine, 2-vinylpyridine, or a mixture thereof. According to any one embodiment of the invention, the vinylpyridine is preferably 4-vinylpyridine.Preferably, block C has a number-average molar mass less than 10,000 g / mol. More preferably, block C has a number-average molar mass greater than 100 g / mol. Even more preferably, block C has a number-average molar mass greater than 100 g / mol and less than 10,000 g / mol.

[0054] Advantageously, in the triblock polymer according to the invention, block A has a number-average molar mass greater than 3,000 g / mol and less than or equal to 30,000 g / mol, block B has a number-average molar mass greater than 100,000 g / mol and less than 200,000 g / mol, and block C has a number-average molar mass less than 10,000 g / mol. Preferably, the triblock polymer has a Mooney viscosity ML(1+4) at 100°C greater than 30. Below a Mooney viscosity value of 30 or less, the finishing steps in the manufacture of the triblock polymer, such as spinning and drying, can become difficult and lead to a decrease in productivity. Preferably, the triblock polymer has a Mooney viscosity ML (1+4) at 100°C greater than or equal to 40. A viscosity value ML (1+4) at 100°C greater than 40 further facilitates the conduct of the finishing steps.The viscosity ML (1+4) at 100°C of the triblock polymer is advantageously less than 70.

[0055] 2024PAT00265WO The triblock polymer according to the invention can be prepared according to a process, which includes the statistical copolymerization of a monomer mixture of ethylene, the first 1,3-diene and the second 1,3-diene in the presence of a catalytic system, and then the subsequent polymerization of vinylpyridine.

[0056] The catalytic system (or catalytic composition) used in the statistical copolymerization of the monomer mixture and in the homopolymerization of vinylpyridine is based on at least one metallocene of formula (I) and one organomagnesium compound of formula (II) PfCp^p 2 ) Nd(BH4)(i +v ) Liy (THF)x (I)

[0057] R-Mg-A (II)

[0058] CP 1 and Cp 2, identical or different, being chosen from the group consisting of cyclopentadienyl groups and fluorenyl groups, the groups being substituted or not, P being a group bridging the two Cp groups 1 and Cp 2 and representing a ZR group 1 R 2 Z represents a silicon or carbon atom, R 1 and R 2 , identical or different, each representing an alkyl group comprising from 1 to 20 carbon atoms, preferably a methyl,

[0059] y, an integer, being equal to or greater than 0,

[0060] x, whether an integer or not, being equal to or greater than 0

[0061] R comprising a benzene nucleus of which two carbon atoms are substituted, one of the two is substituted by a methyl, an ethyl or an isopropyl or forms a ring with the carbon atom which is its nearest neighbor, the second carbon atom being substituted by a methyl, an ethyl or an isopropyl, the magnesium atom being in ortho position with respect to each of said two carbon atoms.

[0062] The symbol A in formula (II) represents the polystyrene block constituting the triblock polymer according to the invention, in other words a polystyrene chain identical to the polystyrene block, block A, of formula ABC.

[0063] In formula (I), the neodymium atom is linked to a ligand molecule consisting of the two Cp groups 1 and Cp 2 connected to each other by bridge P. Preferably, the symbol P, designated as bridge, corresponds to the formula ZR 1 R 2 , Z representing a silicon atom, R1 and R 2 , identical or different, representing an alkyl group comprising from 1 to 20 carbon atoms. More preferably, the P bridge has the formula SiR x R 2 , R 1 and R 2 , being identical and as defined previously. Even more preferably, P satisfies the formula SiMe?.

[0064] Examples of substituted cyclopentadienyl and fluorenyl groups include those substituted with alkyl groups having 1 to 6 carbon atoms, aryl groups having 6 to 12 carbon atoms, or trialkylsilyl groups such as SiMes. The choice among alkyl, aryl, and trialkylsilyl groups is also influenced by the availability of the corresponding molecules, namely the substituted cyclopentadienes and fluorenes, because these are either commercially available or easily synthesized.

[0065] Examples of substituted cyclopentadienyl groups include those substituted at both position 2 (or 5) and position 3 (or 4), particularly those substituted at position 2, more

[0066] 2024PAT00265WO particularly the tetramethylcyclopentadienyl group. In the present application, in the case of the cyclopentadienyl group, position 2 (or 5) designates the position of the carbon atom which is adjacent to the carbon atom to which the P-bridge is attached, as shown in the diagram below.

[0067]

[0068] P

[0069] Examples of substituted fluorenyl groups include those substituted at positions 2,7, 3, or 6, particularly the 2,7-ditertiobutyl-fluorenyl and 3,6-ditertiobutyl-fluorenyl groups. Positions 2, 3, 6, and 7 respectively designate the positions of the carbon atoms in the rings, as shown in the diagram below, with position 9 corresponding to the carbon atom to which the P-bridge is attached.

[0070]

[0071] Preferably, Cp 1 and Cp 2 are identical and are chosen from the group consisting of the substituted fluorenyl groups and the fluorenyl group. Advantageously, in formula (I) Cp 1 and Cp 2Each represents a substituted fluorenyl group or a fluorenyl group, preferably a fluorenyl group. The fluorenyl group has the formula CBHS. Preferably, the metallocene has the formula (la), (Ib), (le), (Id), or (le), in which the symbol Flu represents the fluorenyl group of formula CBHS.

[0072] [{Me2SiFlu2Nd(p-BH4)2Li(THF)}2] (la)

[0073] (Me2SiFlu2Nd(p-BH4)2Li(THF)] (Ib)

[0074] [Me2SiFlu2Nd(p-BH4)(THF)] (the)

[0075] [{Me2SiFlu2Nd(p-BH4)(THF)}2] (Id)

[0076]

[0077] [Me2SiFlu2Nd(p-BH4)] (the)

[0078] The metallocene used to prepare the catalytic system can be in the form of crystalline or non-crystalline powder, or as single crystals. The metallocene can be monomeric or dimeric, depending on the method of preparation, as described in the patent application.

[0079] WO 2007054224. Metallocene can be prepared conventionally by a process analogous to that described in patent application WO 2007054224, in particular by reacting the salt of an alkali metal of the ligand with a rare-earth borohydride under inert and anhydrous conditions in a suitable solvent, such as an ether, like diethyl ether or tetrahydrofuran, or any other solvent known to those skilled in the art. After reaction, the

[0080] 2024PAT00265W 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 then dried and isolated in solid form.

[0081] Like all syntheses carried out in the presence of organometallic compounds, the synthesis of metallocene takes place under anhydrous conditions in an inert atmosphere. Typically, the reactions are conducted using solvents and anhydrous compounds under anhydrous nitrogen or argon.

[0082] The organomagnesium compound of formula (II) is used in the catalytic system as a cocatalyst. Preferably, the two substituents on the two carbon atoms with respect to which the magnesium atom is in the ortho position are identical. More preferably, they are methyl or ethyl. Advantageously, they are methyl.

[0083] Preferably, the organomagnesium compound of formula (II) corresponds to formula (II-1) in which A represents the polystyrene block, Ri and Rs, identical or different, represent a methyl or an ethyl group, and R2, R3, and R4, identical or different, represent a hydrogen atom or an alkyl group. Preferably, Ri and R5 represent a methyl group. Preferably, R2 and R4 represent a hydrogen atom.

[0084]

[0085] According to a preferred variant, Ri, R3, and R5 are identical. According to a more preferred variant, R2 and R4 represent a hydrogen atom, and Ri, R3, and R5 are identical. In a further preferred variant, R2 and R4 represent a hydrogen atom, and Ri, R3, and R5, being identical, represent a methyl or ethyl atom, preferably a methyl atom. The organomagnesium compound of formula (II) can be prepared by a process that includes the reaction of an anionic living polystyrene ALi with a halide of an organomagnesium compound of formula R-Mg-X, R being defined as in formula (II), A representing the polystyrene block, X being a halogen atom, preferably a chlorine or bromine atom, more preferably a bromine atom, the symbol Li representing, in a well-known manner, the lithium atom. Anionic polystyrene is commonly understood to be polystyrene that is prepared by anionic polymerization.Also known is living polystyrene, which has polymer chains with a reactive center for polymerization, typically a carbon-lithium bond, particularly at the end of the polymer chain.

[0086] Living anionic polystyrene is conventionally obtained by anionic polymerization of styrene in a solvent, called the polymerization solvent. The polymerization solvent can be any hydrocarbon solvent known to be used in the

[0087] 2024PAT00265WO Polymerization of styrene. The polymerization solvent is preferably a hydrocarbon solvent, more preferably cyclohexane or toluene.

[0088] The ratio of solvent to styrene required for the formation of anionic styrene is determined by a person skilled in the art based on the desired viscosity of the styrene polymer solution. This viscosity depends not only on the concentration of the polymer solution but also on numerous other factors, such as the length of the polymer chains, the intermolecular interactions between the styrene chains, the complexing power of the solvent, and the temperature of the polymer solution. Therefore, a person skilled in the art adjusts the amount of solvent on a case-by-case basis. To initiate styrene polymerization, compounds well-known to those skilled in the art can be used as initiators for anionic styrene polymerization. An initiator is, for example, a compound that contains a carbon-lithium bond. Examples of initiators include organolithium compounds such as n-butyllithium, sec-butyllithium, and tert-butyllithium.The initiator is used at a rate chosen according to the desired chain length of the living polystyrene.

[0089] The polymerization temperature for forming living polystyrene can vary widely. Traditionally, it ranges from -20 to 100°C, preferably from 20 to 70°C.

[0090] To prepare the organomagnesium compound of formula (II), the reaction of anionic living polystyrene with the halide of an organomagnesium compound can be carried out by adding a solution of the anionic living polystyrene to a solution of the thalide of an organomagnesium compound R-Mg-X, but it is preferably carried out by adding a solution of the thalide of an organomagnesium compound R-Mg-X to a solution of the anionic living polystyrene. The solution of the anionic living polystyrene is generally a solution in a hydrocarbon solvent, preferably the polymerization solvent used for the synthesis of the anionic living polystyrene. The solution of the halide of an organomagnesium compound R-Mg-X is generally a solution in an ether, preferably diethyl ether or dibutyl ether. The concentration of living anionic polystyrene is preferentially from 0.01 to 1 mole of lithium equivalent (eq) / L, more preferably from 0.05 to 0.2 mole of lithium equivalent / L, that of the organomagnesium solution R-Mg-X preferably from 1 to 5 mol / L, more preferably from 2 to 3 mol / L.

[0091] The reaction between living anionic polystyrene and the organomagnesium halide R-Mg-X is typically carried out at a temperature ranging from 0°C to 60°C. Contact is preferably made at a temperature between 0°C and 23°C.

[0092] As with any synthesis involving organometallic compounds, the contact and reaction take place under anhydrous conditions in an inert atmosphere. Typically, solvents and solutions are used under anhydrous nitrogen or argon. The various steps of the process are generally carried out with stirring.

[0093] 2024PAT00265WO Once the organomagnesium of formula (II) has been formed, the solution of the organomagnesium of formula (II) is typically stored before its use as a co-catalyst of the catalytic system in hermetically sealed containers, for example capped bottles, at a temperature between -25°C and 23°C, under an inert and anhydrous atmosphere.

[0094] The catalytic system can be prepared conventionally by a process analogous to that described in patent applications WO 2007054224 or WO 2007054223. For example, the co-catalyst and the metallocene are reacted in a hydrocarbon solvent, typically at a temperature of 20 to 80°C for a duration of 5 to 60 minutes. The amounts of co-catalyst and metallocene reacted are such that the ratio of the number of moles of Mg in the co-catalyst to the number of moles of rare-earth metal in the metallocene is preferably from 1 to 100, and more preferably from 1 to less than 10. The range of values ​​from 1 to less than 10 is particularly favorable for obtaining polymers with high molar masses. The catalytic system is generally prepared in a hydrocarbon solvent, either aliphatic such as methylcyclohexane or aromatic such as toluene.Generally, after its synthesis, the catalytic system is used as is in the polymer synthesis process according to the invention.

[0095] The catalytic system is generally in the form of a solution in a hydrocarbon solvent. The hydrocarbon solvent can be aliphatic, such as methylcyclohexane, or aromatic, such as toluene. The hydrocarbon solvent is preferably aliphatic, and more specifically, methylcyclohexane. Generally, the catalytic system is stored as a solution in the hydrocarbon solvent before being used in polymerization. This can then be referred to as a catalytic solution, which comprises the catalytic system and the hydrocarbon solvent. The concentration of the catalytic solution is typically defined by the metallocene content in the solution. The metallocene concentration is preferably from 0.0001 to 0.2 mol / L, and more preferably from 0.001 to 0.03 mol / L.

[0096] As with any synthesis carried out in the presence of organometallic compounds, the synthesis of the catalytic system takes place under anhydrous conditions in an inert atmosphere. Typically, the reactions are conducted using solvents and anhydrous compounds under anhydrous nitrogen or argon.

[0097] The catalytic system is used for both polymerization steps: the statistical copolymerization of the monomer mixture and the subsequent homopolymerization of vinylpyridine. Both polymerization steps, that of the monomer mixture and that of vinylpyridine, are preferably carried out in solution, either continuously or batchwise, in a suitably stirred reactor. The polymerization solvent can be a hydrocarbon, aromatic, or aliphatic solvent. Examples of polymerization solvents include toluene and methylcyclohexane.

[0098] The catalytic system is generally introduced into the reactor containing the polymerization solvent and the monomer mixture containing ethylene, the first 1,3-diene, and the second 1,3-diene. To achieve the desired macrostructure of block B, a person skilled in the art adjusts the polymerization conditions, particularly the molar ratio of the organomagnesium compound.

[0099] 2024PAT00265WO on the Nd metal constituting the metallocene. The molar ratio can reach the value of 100, knowing that a molar ratio less than 10 is more favorable for obtaining polymers with high molar masses.

[0100] Block B is prepared by the statistical copolymerization of a mixture of ethylene monomer, the first 1,3-diene, and the second 1,3-diene. Preferably, a continuous addition of ethylene, the first 1,3-diene, and the second 1,3-diene is carried out in the polymerization reactor, in which case the polymerization reactor is a fed reactor. This embodiment is particularly suitable for the statistical incorporation of ethylene, the first 1,3-diene, and the second 1,3-diene.

[0101] The polymerization temperature generally varies from 30 to 160°C, preferably from 30 to 120°C. During the preparation of block B, the temperature of the reaction medium is advantageously kept constant during copolymerization, and the total pressure in the reactor is also advantageously kept constant. The preparation of block B is completed by stopping the monomer supply, notably by dropping the reactor pressure, preferably to about 0.1 bar.

[0102] The preparation of the polyvinylpyridine block, block C, by the subsequent polymerization of vinylpyridine, proceeds by adding vinylpyridine to the reactor. Vinylpyridine can be added to the reactor pure or diluted in a hydrocarbon solvent, preferably aliphatic such as methylcyclohexane. The vinylpyridine, pure or diluted, is introduced into the degassed reaction medium. The amount of vinylpyridine introduced into the reaction medium to be polymerized to form block C is adjusted by those skilled in the art according to the desired percentage of vinylpyridine in block form within the triblock polymer. It can vary, in particular, from 0.01 to 25 g per 100 g of block B formed, and more specifically from 2 g to 25 g per 100 g of block B formed. The homopolymerization of vinylpyridine is preferably carried out at the same temperature as the synthesis of block B.According to any one embodiment of the invention, the polymerization temperature for the synthesis of block C generally varies in the range of 30 to 160°C, preferably from 30 to 120°C. The synthesis of block C can typically be monitored by chromatographic analysis to track the consumption of vinylpyridine. The synthesis of block C is complete when block C reaches the desired number-average molar mass or when the conversion of the vinylpyridine polymerization reaction reaches the desired conversion rate, for example, 100%.

[0103] The synthesis of the C-block can be stopped by cooling the polymerization medium or by adding an alcohol, preferably one containing 1 to 3 carbon atoms, such as ethanol. The triblock 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 steam stripping.

[0104] Alternatively, the triblock polymer can be prepared by another process which differs from that described in that the co-catalyst is not the organomagnesium compound of formula (II), but the living anionic polystyrene ALi, and that the molar ratio between the number of moles of

[0105] 2024PAT00265WO living polymer and the number of moles of Nd atoms in the metallocene varies in a range from 0.8 to 1.2.

[0106] The triblock polymer is typically an elastomer and can be used in a rubber composition, another object of the invention.

[0107] The rubber compound may include any type of reinforcing filler known for its ability to strengthen a rubber compound suitable for tire manufacturing, such as carbon black, silica combined with a known coupling agent, or a mixture of these two types of filler. Such a reinforcing filler typically consists of nanoparticles with an average size (by mass) of less than one micrometer, generally less than 500 nm, most often between 20 and 200 nm, and more preferably between 20 and 150 nm. The reinforcing filler content is adjusted by a person skilled in the art according to the intended use of the rubber compound. According to any one embodiment of the invention, the reinforcing filler preferably comprises silica, and more preferably more than 50% by mass of silica.

[0108] All carbon blacks conventionally used in tire rubber compounds (so-called tire-grade blacks) are suitable as substitutes for carbon black. When present, carbon black is preferably used at a concentration below 20 parts per liter (ppm), and more preferably below 10 ppm (for example, between 0.5 and 20 ppm, particularly between 2 and 10 ppm). Within these ranges, the coloring (black pigmenting agent) and UV-resistant properties of carbon blacks are utilized without compromising the typical performance provided by silica.

[0109] To couple silica to the polymer, a coupling agent, in particular a silane (or bonding agent), is used in a well-known manner. This agent must be at least bifunctional and designed to ensure sufficient connection between the silica (surface of its particles) and the polymer. Organosilanes or polyorganosiloxanes, at least bifunctional, are used in particular. Polysulfide silanes, described as "symmetric" or "asymmetric" depending on their specific structure, are notably used, as described, for example, in applications W003 / 002648 (or

[0110] US 2005 / 016651) and W003 / 002649 (or US 2005 / 016650). In particular, but not limited to, polysulfide silanes conforming to the general formula (III) are suitable.

[0111] J - G - Sx - GJ (III)

[0112] in which:

[0113] - x is an integer from 2 to 8 (preferably from 2 to 5);

[0114] - The symbols G, whether identical or different, represent a divalent hydrocarbon radical (preferably an alkylene group in the C1-C1S position or an arylene group in the C2-C1N position, more particularly an alkylene in the C1-C1O position, especially in C1-C4, in particular propylene); - The symbols J, whether identical or different, correspond to one of the three formulas below:

[0115] 2024PAT00265WOR1

[0116] — If— R2

[0117]

[0118] R2

[0119] in which:

[0120] - the radicals R 1 , substituted or unsubstituted, identical or different from each other, represent a C1-C18 alkyl group, a C5-C18 cycloalkyl group or a C1-C18 aryl group (preferably C1-C18 alkyl groups, cyclohexyl or phenyl groups, especially C1-C4 alkyl groups, more particularly methyl and / or ethyl),

[0121] - the radicals R 2, substituted or unsubstituted, identical or different from each other, represent a C5-C18 alkoxyl group in Ci-Cis or cycloalkoxyl (preferably a group chosen from C5-C8 alkoxyls and cycloalkoxyls, more preferably a group chosen from C1-C4 alkoxyls, in particular methoxyl and ethoxyl).

[0122] In the case of a mixture of polysulfurized alkoxysilanes conforming to formula (III) above, particularly common commercially available mixtures, the average value of "x" is a fractional number preferably between 2 and 5, more preferably close to 4. But the invention can also be advantageously implemented, for example, with disulfurized alkoxysilanes (x = 2). By way of examples of polysulfurized silanes, particular mention will be made of the polysulfides (in particular disulfides, trisulfides or tetrasulfides) of bis-(alkoxyl(Ci-C4)-alkyl(Ci-C4)silyl-alkyl(Ci-C4)), such as, for example, the polysulfides of bis(3-trimethoxysilylpropyl) or bis(3-triethoxysilylpropyl). Among these compounds, in particular, the tetrasulfide of bis(3-triethoxysilylpropyl), abbreviated TESPT, with the formula [(C2HsO)3Si(CH2)3S2]2, or the disulfide of bis-(triethoxysilylpropyl), abbreviated TESPD, with the formula [(C2H5O)3Si(CH2)3S]2, is used.

[0123] The coupling agent content is advantageously less than 30 parts per liter, it being understood that it is generally desirable to use as little as possible. Typically, the coupling agent content represents 0.5% to 15% by weight relative to the amount of silica. Its content is preferably between 0.5% and 16 parts per liter, and more preferably within the range of 3% to 10%. This content is easily adjusted by those skilled in the art according to the amount of silica used in the composition.

[0124] The reinforcing load ratio varies preferentially between 40 pc and 160 pc.

[0125] Advantageously, the reinforcing filler ratio varies preferentially between 40 pc and 160 pc and silica represents more than 50% by mass of the reinforcing filler.

[0126] The crosslinking system may be based on sulfur, sulfur donors, peroxides, bismaleimides, or mixtures thereof. According to any one embodiment of the invention, the crosslinking system is preferably a vulcanization system, that is, a system based on sulfur (or a sulfur-donating agent) and a primary vulcanization accelerator. Various known secondary accelerators or vulcanization activators, such as zinc oxide, stearic acid or equivalent compounds, guanidine derivatives (in particular diphenylguanidine), or known vulcanization retarders, may be added to this basic vulcanization system. Sulfur is used at a preferential rate of

[0127] 2024PAT00265WO 0.5 to 12 parts per liter, in particular 1 to 10 parts per liter. The primary vulcanizing accelerator is used at a preferential rate between 0.5 and 10 parts per liter, more preferably between 0.5 and 5 parts per liter. Any compound capable of acting as a vulcanizing accelerator for diene elastomers in the presence of sulfur may be used as an accelerator (primary or secondary), in particular thiazole-type accelerators and their derivatives, thiuram-type accelerators, and zinc dithiocarbamates. Preferably, a sulfenamide-type primary accelerator is used.

[0128] The rubber composition according to the invention may also include all or part of the usual additives commonly used in elastomer compositions intended to constitute external compounds of finished rubber articles such as tires, in particular treads, such as plasticizers or extending oils, pigments, protective agents such as anti-ozone waxes, chemical anti-ozonants, antioxidants.

[0129] The rubber composition according to 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 mixing phase (the so-called "non-productive" phase) at high temperature of the ingredients of the rubber composition, with the exception of the crosslinking system, up to a maximum temperature between 130°C and 200°C, followed by a second mechanical working phase (the so-called "productive" phase) down to a lower temperature, typically below 110°C, for example between 40°C and 100°C, a finishing phase during which the crosslinking system is incorporated.

[0130] After the incorporation of all the ingredients of the rubber composition, the final composition thus obtained can be calendered, for example in the form of a sheet or plate, particularly for characterization in the laboratory, or extruded, for example to form a rubber profile used as a rubber component or semi-finished product, particularly for the manufacture of a tire.

[0131] Thus, according to a particular embodiment of the invention, the rubber composition according to the invention, which can be either in the raw state (before crosslinking or vulcanization) or in the cooked state (after crosslinking or vulcanization), is in a tire, for example in a tire tread.

[0132] Crosslinking (or curing), where applicable vulcanization, is carried out in a known manner at a temperature generally between 130°C and 200°C, for a sufficient time which can vary for example between 5 and 120 min depending in particular on the curing temperature, the crosslinking system adopted and the crosslinking kinetics of the composition considered.

[0133] The rubber composition according to the invention, which can be either in the raw state (before crosslinking or vulcanization) or in the cured state (after crosslinking or vulcanization), can be used in a semi-finished article for pneumatics.

[0134] 2024PAT00265WO The tire, another object of the invention, which includes a tread, comprises the rubber composition according to the invention defined under any one of the embodiments of the invention, preferably in its tread.

[0135] In the present invention, the term "pneumatic" (in English, "tire") refers to a pneumatic or non-pneumatic tire. A pneumatic tire typically comprises two beads for contact with a rim, a crown consisting of at least one crown reinforcement and a tread, and two sidewalls. The tire is reinforced by a carcass reinforcement anchored in the two beads. A non-pneumatic tire, on the other hand, typically comprises a base, designed, for example, for mounting on a rigid rim, a crown reinforcement connecting to a tread, and a deformable structure, such as spokes, ribs, or dimples, this structure being arranged between the base and the crown. Such non-pneumatic tires do not necessarily include sidewalls. Non-pneumatic tires are described, for example, in documents WO 03 / 018332 and FR2898077.According to any one embodiment of the invention, the tire according to the invention is preferably a pneumatic tire. The aforementioned features of the present invention, as well as others, will be better understood upon reading the following description of several illustrative and non-limiting examples of embodiments of the invention.

[0136] Examples

[0137] The name EBMR is used to designate a statistical copolymer of ethylene, 1,3-butadiene and myrcene; the name VP is used to designate a homopolymer of 4-vinylpyridine; the name PS is used to designate a homopolymer of styrene; the name Mes is used to designate the mesityl group.

[0138] All reagents are obtained commercially except for the metallocene of formula [{Me2SiFlu2Nd(p-BH4)2Li(THF)}2] which is prepared according to the procedure described in document WO 2007054224.

[0139] Styrene (Sigmal-Aldrich) is dried for 24 hours on CaFL and then distilled under vacuum.

[0140] The ethylene, of N35 grade, comes from the company Air Liquide and is used without prior purification.

[0141] 1,3-Butadiene is purified over alumina guards.

[0142] The myrcene, with a purity of 92.5% by weight, comes from the company DRT and is purified on an alumina column.

[0143] 2-mesitylmagnesium bromide, at 1 mol / L in THF, comes from Sigma-Aldrich (2-mesitylmagnesium bromide).

[0144] Lithium-butyl (1.6 M in hexane, Sigma-Aldrich) is used as received.

[0145] Also from Sigma-Aldrich are 4-vinylpyridine and sec-BuLi at 1.4 M in cyclohexane.

[0146] 4-Vinylpyridine is purified according to the following procedure: 100 mL of 4-vinylpyridine (Sigma-Aldrich, 95% purity, containing 100 ppm hydroquinone) are placed in a Steinie bottle containing 30 g of alumina. The bottle is then capped and shaken for 30 minutes at room temperature (23 °C) protected from light.

[0147] 2024PAT00265WO Butylloctylmagnesium BOMAG (20% by mass in heptane, C = 0.88 mol L' 1 ) comes from Lanxess and is stored in a metal cylinder under an inert atmosphere.

[0148] The purified polymerization solvents (toluene, methylcyclohexane, cyclohexane) are purified through three alumina columns. The methylcyclohexane solvent from BioSolve is dried and purified on alumina columns in a solvent fountain from mBraun, operated in an inert atmosphere.

[0149] All reactions are carried out in an inert atmosphere (argon) in Steinie bottles and sealed, inert reactors.

[0150] Mooney viscosity measurement:

[0151] To measure Mooney viscosity, an oscillating consistometer as described in ASTM DI 646-2007 (Reapproved 2012) is used. The Mooney viscosity measurement is performed according to the following principle: the elastomer is molded in a cylindrical chamber heated to 100°C under pressure. After a one-minute preheating period, the rotor rotates within the specimen at 2 revolutions per minute, and the torque required to maintain this rotation is measured after 4 minutes of 8 rotations. The Mooney viscosity (ML 1+4) is expressed in Mooney units (LM, with 1 LM = 0.83 Newton-meters).

[0152] Nuclear magnetic resonance (NMR):

[0153] Nuclear magnetic resonance (NMR):

[0154] Spectra were acquired on a Brüker Avance III 500 MHz spectrometer equipped with a 5 mm BBIz-grad "broadband" cryo-probe. Samples were solubilized in CDCh chloroform. Calibration was performed on the protonated impurity of deuterated chloroform at 7.26 ppm by NMR. X H. The quantitative 'H' NMR experiment uses a simple 30° pulse sequence and a 5-second repetition delay between each acquisition.

[0155] Nuclear magnetic resonance (NMR) (block polymer synthesis):

[0156] The block polymers are solubilized in CDCh chloroform. Calibration is performed on the protonated impurity of deuterated chloroform at 7.26 ppm by NMR. XH. The quantitative ¹H NMR experiment uses a simple 30° pulse sequence and a 5-second repetition delay between each acquisition. 64 to 256 accumulations are performed. Two-dimensional ¹H / ¹³C experiments are used to determine the unit structure of polymers. The ¹H-¹³C HMBC (heteronuclear multiple bond correlation) experiment detects long-range correlations via J-coupling between protons and carbon-13 nuclei. The ¹H NMR spectra and the edited ²D ¹H / ¹³C IJ HSQC NMR correlation spectrum allow for the determination of the block polymer microstructure and the proportion of each block in the sample.

[0157] Determination of the percentage of block polymer by DOSY:

[0158] The DOSY experiment, an NMR method, allows for the analysis of complex mixtures and the detection of trace elements. The aim of this experiment is to demonstrate that the block polymer constitutes the majority of the sample and that the presence of homopolymer is very low. DOSY NMR analysis allows for the separation of the species present, particularly polymer matrices, by analyzing their diffusion coefficient in solution. The principle of the technique is as follows: The DOSY experiment consists of recording proton spectra in

[0159] 2024PAT00265WO by varying the applied gradient force G and thus the diffusion force. A linear increase in the gradient intensity will lead to an exponential decrease in the NMR signal intensity. The DOSY experiment will produce a two-dimensional map.

[0160] The second dimension F2 of the DOSY corresponds, after processing by the Fourier transform, to the dimension 1H. The first dimension Fl corresponds to the decay of the NMR signal as a function of the applied gradient force. After processing the dimension F2, the diffusion coefficient is extracted from equation (1), and a DOSY map is obtained.

[0161] I = I0.exp(-Dy 2 G 2 oh 2 (A-ô / 3)) (1)

[0162] If the two matrices have the same diffusion coefficient, this means that the two matrices have the same hydrodynamic radius and are therefore grafted. Conversely, if the two matrices have different diffusion coefficients, this means that they are free from each other.

[0163] The equation that describes the diffusion coefficient is as follows:

[0164] k E T

[0165] O ss — - —

[0166]

[0167] érmrs

[0168] The experiment was conducted on samples of poly(styrene-b-poly(ethylene-co-myrcene) and poly(styrene-b-poly(ethylene-co-myrcene)-b-4-vinylpyridine) synthesized according to the process according to the invention.

[0169] Recording two 1H ID NMR spectra with a scattering filter, one with a magnetic field gradient set at 90% of the maximum power of the gradient amplifier and the other at 1% of this value, allows, by comparison with the 1H NMR spectrum, observation of the signal loss due to spatial scattering of molecules and magnetization relaxation. The signal loss due to scattering is then attributed to "small molecules" not bound to the polymer matrix (reagents, antioxidants, solvents, etc.).

[0170] High-temperature size exclusion chromatography (SEC-3D):

[0171] The number-average molar mass (Mn), weight-average molar mass (Mw), and polydispersity index of the prepared polymers (hereafter referred to as the sample) are determined absolutely by triple-detection size exclusion chromatography (SEC-3D). Triple-detection size exclusion chromatography has the advantage of directly measuring average molar masses without calibration. SEC / 3D analyses are performed on a WATERS system equipped with three mixed-BLS columns and Wyatt refractometric, differential viscometric, and light-scattering detectors. Samples are prepared at a concentration of 5 g / L. 1 in tetrahydrofuran and the analyses are carried out at 35°C at a flow rate of 1 mL min' 1The mobile phase flow rate is 1 mL / min. Data are acquired and processed using ASTRA software, and the dn / dc of ethylene-based copolymers is assumed to be 0.1000 by default.

[0172] Differential scanning calorimetry (DSC):

[0173] The glass transition temperature (Tg) of the polymers is determined by differential scanning calorimetry (DSC). DSC analyses are performed on a DSC 3+ instrument (Mettler Toledo) with sealed aluminum crucibles (40 pL) and under a nitrogen flow (20 mL min⁻¹). 1 The thermograms of homopolymers, diblock and triblock polymers are

[0174] 2024PAT00265WO obtained according to the following program repeated 3 times: ramp from +180 °C to -80 °C to 10 °C min' 1 , isothermal temperature of 5 min at -80 °C, ramp from -80 °C to +180 °C at 10 °C min' 1 , isothermal for 5 minutes at +180 °C.

[0175] Dynamic properties:

[0176] Dynamic properties are measured according to ASTM D 5992-96 and ASTM D 1349-99 standards. The tan(φ) values, noted as "tan(φ) 100°C", are taken from a temperature sweep at 0.7 MPa at 100°C. They indicate the dry surface adhesion performance: the higher the tan(φ) value, the better the corresponding adhesion performance. Results are given on a scale of 100 relative to a control.

[0177] Polymer synthesis:

[0178] Example 1: Synthesis of an EBMR polymer (block B):

[0179] In an 80 L reactor, 53 L of methylcyclohexane and 400 mL of a BOMAG solution in methylcyclohexane at a concentration of 0.0134 mol / L are added. The temperature in the reactor is raised to 80°C and the monomers 1,3-butadiene, myrcene and ethylene are injected at a controlled rate into the reactor, respecting a mass ratio (g / g) myrcene / ethylene = 1.59 and 1,3-butadiene / ethylene = 0.24, until a pressure of 6 bars is obtained in the reactor.

[0180] The catalytic system (5.99 mmol of Nd) is injected into the reactor ca t, or 3.8 g of Nd cat) to a concentration of 0.0062 mol / L in methylcyclohexane to initiate the polymerization reaction of ethylene, 1,3-butadiene, and myrcene. The polymerization temperature is regulated at 80°C, and the pressure in the reactor is increased to 8 bar. The pressure in the reactor is maintained constant at 8 bar by feeding 1,3-butadiene, myrcene, and ethylene throughout the polymerization reaction at the mass ratios myrcene / ethylene = 1.59 and 1,3-butadiene / ethylene = 0.24.

[0181] The conversion of the polymerization reaction is measured by dry extract, and when a mass of 5.3 kg of polymer is reached after 70 min of polymerization, the injection of monomers into the reactor is stopped. The weighed mass of copolymer, 5.4 kg after 74 min, allows the determination of the average catalytic activity of the catalytic system, expressed in kilograms of polymer synthesized per mole of neodymium metal per hour (kg / mol·h), as 827 kg / mol·h.

[0182] 550 mL of 1 mol / L ethanol is injected to stop polymerization. 226 mL of an antioxidant, Irganox 1520L at 218 g / L, is injected into the reactor. The reactor contents are transferred to another reactor, called a "stripping reactor," to remove the solvent by steam distillation while maintaining a temperature of 100°C. The copolymer is collected and then dried for 48 hours in an oven at 60°C under vacuum and nitrogen purging.

[0183] Example 2: Synthesis of a triblock polymer PS-Z>-EBMR-Z>-VP (triblock polymer of formula ABC)

[0184] L ere Step: Synthesis of the first block (block A) and transmetallation reaction:

[0185] In an 80 L reactor containing cyclohexane (11.5 L) and heated to 40°C, we introduce

[0186] 2024PAT00265WO 1.2 L of styrene (10.6 mol). The polymerization of styrene is initiated by a solution of sec-butyllithium (55 mmol, 0.5 L) at a concentration of 0.11 mol / L in methylcyclohexane. The conversion of styrene is monitored by dry extract and a 100% conversion is achieved after 35 min, yielding 1.1 kg of polystyrene.

[0187] Once the living polystyrene (PSLi) is formed, a transmetallation reaction is carried out to form the PSMgMes species. For this, 2-mesitylmagnesium bromide is injected in toluene solution at a concentration of 0.5 mol / L (1 eq / Li, 122 mL) into an 80 L reactor at a temperature of 40°C. The temperature in the reactor is maintained at 40°C for 10 min.

[0188] Next, 39.1 L of cyclohexane is introduced into the polymerization reactor and the polymer solution is heated to 80°C in the reactor.

[0189] 2 eme Step: Synthesis of the second block (block B):

[0190] During the temperature rise of the polymer solution (up to 80°C), the monomers 1,3-butadiene, myrcene and ethylene are injected at a controlled rate into the reactor, respecting a mass ratio (g / g) myrcene / ethylene = 1.59 and butadiene / ethylene = 0.24, until a pressure of 6 bars is obtained in the reactor.

[0191] The metallocene {Me2Si(Ci3H8)2Nd(BH4)2.Li(THF)}2 (Nd ca t) (5.99 mmol of Nd, or 3.8 g of Nd) in solution in 500 mL of cyclohexane. The polymerization temperature is regulated at 80°C, and the pressure in the reactor is increased to 8 bar. The pressure in the reactor is maintained constant at 8 bar by feeding 1,3-butadiene, myrcene, and ethylene throughout the polymerization reaction at the mass ratios myrcene / ethylene = 1.59 and 1,3-butadiene / ethylene = 0.24.

[0192] The conversion of the polymerization reaction is measured by dry extract, and when the mass of 4.9 Kg corresponding to the formation of the second block is reached after 118 min of polymerization of ethylene, 1,3-butadiene and myrcene, the injection of monomers into the reactor is stopped.

[0193] The mass weighed corresponding to the formation of the second block, 4.9 Kg, allows us to determine the average catalytic activity of the catalytic system expressed in kilograms of polymer synthesized per mole of neodymium metal per hour (kg / mol.h), of 458 Kg / mol.h.

[0194] 3 eme Step: Synthesis of the third block (block C):

[0195] 268 mL of a pure 4-vinylpyridine solution (5% mass of the target PS-b-EBMR block polymer mass, i.e. a target Mn of block C of 5500 g / mol) are then transferred by overpressure into the reactor.

[0196] The temperature in the reactor is maintained at 80°C throughout the 4-vinylpyridine polymerization reaction (30 min). Then, 550 mL of 1 mol / L ethanol is injected to stop the polymerization reaction. 226 mL of the antioxidant Irganox 1520L at 218 g / L is injected into the reactor. The reactor contents are transferred to another reactor, called the "stripping reactor," to remove the solvent by steam distillation while maintaining a temperature of 100°C. The polymer is then recovered and dried on an extrusion line.

[0197] The mass weighed corresponding to the formation of the first two blocks is 5.3 kg. The microstructure and macrostructure characteristics of the triblock are shown in Table 1.

[0198] 2024PAT00265WO The rate of units is expressed as a mole percentage calculated relative to the total number of moles of styrene, ethylene, myrcene, 1,3-butadiene and 4-vinylpyridine inserted into the polymer chain.

[0199] The microstructure and macrostructure characteristics of the synthesized polymers are shown in Table 1. The rate of units is expressed as a mole percentage calculated relative to the total number of moles of styrene, ethylene, myrcene, 1,3-butadiene and 4-vinylpyridine inserted into the polymer chain.

[0200] Table 1:

[0201] Example Example 1 Example 2

[0202] EBMR PS-Z polymer > EBMR-Z > VP

[0203] Ethylene (%mol) 75 68

[0204] Styrene (%mol) 0 9

[0205] Myrcene (%mol) 14 11

[0206] 1,3-Butadiene (%mol) 8 7

[0207] Cyclohexanediyl (%mol) 3 4

[0208] 4-Vinylpyridine (%mol) 0 1

[0209] Mn block PS (g / mol) NA 22800

[0210] Dispersion block PS NA 1.02

[0211] Mn polymer (g / mol) 140900 161800

[0212] Polymer dispersion 1.54 1.36

[0213] ML polymer 44.8 79.5

[0214]

[0215] Tg (°C) polymer -54 -53

[0216] Preparation of rubber compounds:

[0217] Rubber compositions are prepared according to the following procedure:

[0218] Rubber compositions, whose formulation expressed in parts per hundred parts of elastomer (pce) is shown in Tables 2 and 3, were prepared in an internal mixer. The copolymer, reinforcing filler, and various other ingredients, with the exception of the vulcanizing system, were introduced sequentially. A thermomechanical process (non-productive phase) was then carried out in a single step, lasting approximately 5 minutes, until a maximum "drop" temperature of 150°C was reached. The resulting mixture was collected, cooled, and then sulfur and an accelerator were incorporated in a mixer (homo-finisher) at 40°C, where the mixture was blended for about ten minutes (productive phase). The compositions thus obtained were then calendered into either sheets (2 to 3 mm thick) or thin sheets of rubber for the measurement of their physical and mechanical properties after vulcanization at 150°C.The applied crosslinking time, T(99), is the time required for the couple.

[0219] 2024PAT00265WOdes compositions of the invention reach 99% of the maximum torque of these compositions, i.e. 20 minutes.

[0220] (1) PI, Example 1 Polymer

[0221] (2) P2, Polymer of example 2

[0222] (3) “Zeosil 1165 MP” from Solvay-Rhodia in the form of microbeads, CTAB 160 m 2 / g, precipitated silica

[0223] (4) ASTM N234 Grade Carbon Black

[0224] (5) “Su-640” resin from Kolon Industries (Tg= 83 °C, 100% aliphatic, Mn 398 g / mol).

[0225] (6) Liquid silane triethoxysilylpropyltetrasulfide (TESPT) “Si69” from Evonik (7) N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine “Santaflex 6PPD” from Flexys

[0226] (8) Diphenylguanidine “Perkacit DPG” from the company Flexsys

[0227] (9) Stearic acid “Pristerene 4931” from the company Uniqema

[0228] (10) Industrial grade zinc oxide from Umicore

[0229] (11) N-cyclohexyl-2-benzothiazol-sulfenamide “Santicure CBS” from Flexsys. Compositions C1 and C3, which contain a polymer not according to the invention, PI, are compositions not according to the invention. Compositions C2 and C4, which contain a block polymer according to the invention, P2, are compositions according to the invention. These are the ones that exhibit the highest hysteresis at high temperature (100°C). Table 2:

[0230] Ingredients Composition Cl Composition C2

[0231] Pl (l) 100

[0232] P2 (2) 100

[0233] Silica (3) 86 86

[0234] N234 (4) 3 3

[0235] Plasticizing resin (5) 30 30

[0236] Si69 (6) 6.88 6.88

[0237] 6PPD (7) 3.8 3.8

[0238] DPG (8) 1.72 1.72

[0239] Stearic acid (9) 3 3

[0240] ZnO (10) 0.9 0.9

[0241] Soluble sulfur 0.9 0.9

[0242] CBS (11) 2.3 2.3

[0243] Cooked properties

[0244]

[0245] tan(φ) 100°C 100 185

[0246] Table 3:

[0247] Ingredients Composition C3 Composition C4

[0248] Pl (l) 100

[0249] P2 (2) 100

[0250]

[0251] Silica (3) 69 69

[0252] 2024PAT00265WON234 (4) 3 3

[0253] Si69 (6) 5.52 5.52

[0254] 6PPD (7) 3.8 3.8

[0255] DPG (8) 1.38 1.38

[0256] Stearic acid (9) 3 3

[0257] ZnO (10) 0.9 0.9

[0258] Soluble sulfur 0.9 0.9

[0259] CBS (11) 2.3 2.3

[0260] Cooked properties

[0261]

[0262] tan(φ) 100°C 100 275

[0263] The results show that the addition of two terminal blocks, respectively a polystyrene and a polyvinylpyridine, to an EBMR chain significantly increases the hysteresis at 100°C of the rubber compositions.

[0264] 2024PAT00265WO

Claims

Demands 1. Triblock polymer of formula ABC in which the symbol A represents a polystyrene block, the symbol B represents an elastomer block and the symbol C represents a polyvinylpyridine block, the styrene units of block A being present in the triblock polymer at a molar content of less than 15% of the repeating motifs constituting the triblock polymer, the elastomer block being a statistical copolymer of ethylene, a first 1,3-diene and a second 1,3-diene, the first 1,3-diene being 1,3-butadiene or isoprene, the second 1,3-diene being a 1,3-diene of formula CH2=CR'-CH=CH2, the symbol R' representing a hydrocarbon chain having 3 to 20 carbon atoms, the vinylpyridine units of block C being present in the triblock polymer in a molar content of less than 5% of the repeating motifs constituting the triblock polymer.

2. Triblock polymer according to claim 1 in which the ethylene units of block B represent more than 50% by mole of the repeating motifs constituting block B.

3. Triblock polymer according to any one of claims 1 to 2 wherein the ethylene units of block B represent at most 85% by mole of the repeating motifs constituting block B.

4. Triblock polymer according to any one of claims 1 to 3 wherein block B contains less than 30 mole percent of units of the second 1,3-diene.

5. Triblock polymer according to any one of claims 1 to 4 in which block B contains at least 1 mole percent of units of the second 1,3-diene.

6. Triblock polymer according to any one of claims 1 to 5 wherein the second 1,3-diene is myrcene or P-farnesene or a mixture of myrcene and P-farnesene, preferably myrcene.

7. Triblock polymer according to any one of claims 1 to 6 in which block B contains less than 30 mole percent of units of the first 1,3-diene.

8. Triblock polymer according to any one of claims 1 to 7 wherein the first 1,3-diene is 1,3-butadiene.

9. Triblock polymer according to claim 8 in which the triblock polymer contains 1,2-cyclohexanediyl motifs.

10. Triblock polymer according to any one of claims 1 to 9 wherein block A has a number-average molar mass greater than 3,000 g / mol and less than or equal to 30,000 g / mol, block B has a number-average molar mass greater than 100,000 g / mol and less than 200,000 g / mol, block C has a number-average molar mass less than 10,000 g / mol.

11. Rubber composition comprising a triblock polymer according to any one of claims 1 to 10, a reinforcing filler and a crosslinking system.

12. A tire comprising a tread, which tire comprises a rubber composition defined in claim 11.

13. Process for synthesizing a triblock polymer of formula ABC, where A represents a polystyrene block, B represents an elastomer block which is a random copolymer of ethylene, a first 1,3-diene and a second 1,3-diene, the first 1,3-diene being 1,3-butadiene or isoprene, the second 1,3-diene being a 1,3-diene of formula 2024PAT00265WOCH2=CR'-CH=CH2, where R' represents a hydrocarbon chain with 3 to 20 carbon atoms, and C represents a polyvinylpyridine block, which process comprises, in the presence of a catalytic system based on at least one metallocene of formula (I) and an organomagnesium compound of formula (II), the statistical copolymerization of a monomer mixture of ethylene, the first 1,3-diene and the second 1,3-diene, followed by the homopolymerization of a vinylpyridine, P(Cp 1 CP 2 ) Nd(BH4)(i + v) Liy (THF)x (I) R-Mg-A (II) CP 1 and Cp 2 , identical or different, being chosen from the group consisting of cyclopentadienyl groups and fluorenyl groups, the groups being substituted or not, P being a group bridging the two Cp groups 1 and Cp 2 and representing a ZR group 1 R 2 Z represents a silicon or carbon atom, R 1 and R 2 , 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, whether an integer or not, being equal to or greater than 0, R comprising a benzene ring of which two carbon atoms are substituted, one of the two is substituted by a methyl, an ethyl or an isopropyl or forms a ring with the carbon atom which is its nearest neighbor, the second carbon atom being substituted by a methyl, an ethyl or an isopropyl, the magnesium atom being in ortho position with respect to each of said two carbon atoms, the symbol A in formula (II) representing the polystyrene block constituting the triblock polymer.

14. A process according to claim 13 wherein the organomagnesium of formula (II) corresponds to formula (II-1) in which A represents the polystyrene block, Ri and Rs, identical or different, represent a methyl or an ethyl and R2, R3 and R4, identical or different, represent a hydrogen atom or an alkyl.

15. Method according to claim 14 wherein R2 and R4 represent a hydrogen atom and Ri, R3 and R5, identical, represent a methyl or an ethyl. 2024PAT00265WO

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