DIORGANOMAGNESIUM HAVING A DIENE OR OLEFINIC CHAIN AND AMINE FUNCTION

Description

[0001] The field of the present invention is that of organomagnesium compounds used as co-catalysts in a catalytic system for the preparation of polymers which are both block copolymers based on ethylene and a comonomer, and amine functional polymers, the comonomer being a conjugated diene or an α-monoolefin.

[0002] Organomagnesium compounds are known to be used as co-catalysts in rare-earth metallocene-based catalytic systems to prepare olefin and 1,3-diene copolymers. See, for example, patent applications EP 1 092 731, WO 2004035639, WO 2007054224, and WO 2018224776. These organomagnesium compounds are typically organomagnesium halide compounds such as organomagnesium chloride or dialkylmagnesium compounds such as dibutylmagnesium, butylethylmagnesium, and butyloxylmagnesium.

[0003] It is also known to prepare block polymers comprising a homopolymer block of a 1,3-diene and a copolymer block of ethylene and 1,3-diene. For example, patent application WO 2019077232 describes a process for synthesizing such block polymers by reacting a living homopolymer obtained by anionic polymerization of a 1,3-diene with a rare-earth metallocene in the presence of a cocatalyst, followed by the subsequent polymerization of a mixture of ethylene and a 1,3-diene. A drawback of this process is the low catalytic activity associated with the metallocene activation reaction, which requires equal moles of metallocene and cocatalyst.

[0004] It is also known to prepare ethylene and 1,3-diene block copolymers by subsequent polymerization of different monomer fillers, as described for example in patent application EP 2599809.

[0005] Copolymers of ethylene and 1,3-diene that are statistical and bear an amine group at the end of the chain are also known. For example, they can be prepared by a process described in patent application WO 201709783, which uses an organomagnesium compound bearing an amine group as a co-catalyst.

[0006] The Applicants have discovered a synthetic route that enables the preparation, via catalytic polymerization with strong catalytic activity, of ethylene-comonomer-based copolymers that are both block polymers and chain-end amine functional polymers, the comonomer being a conjugated diene or an α-monoolefin. The synthesis is made possible by the use of a novel organomagnesium cocatalyst in a catalytic system comprising a rare-earth metallocene.

[0007] Thus, a first object of the invention is a diorganomagnesium compound of formula (I) RB< -Mg-R A< (I) RA< being different from RB<, RA< being a polymer chain of a first monomer chosen from the group of monomers consisting of 1,3-dienes, aromatic α-monolefins and mixtures thereof, the polymer chain having a first end bonded to the magnesium atom and a second end bearing an amine function, RB< comprising a benzene ring substituted by the magnesium atom, one of the carbon atoms of the benzene ring ortho to the magnesium being substituted by a methyl, an ethyl, an isopropyl or forming a ring with its nearest neighbor carbon atom meta to the magnesium, the other carbon atom of the benzene ring ortho to the magnesium being substituted by a methyl, an ethyl or an isopropyl, provided that if one of the two ortho carbon atoms is substituted by an isopropyl, the second ortho carbon atom is not not substituted by an isopropyl.

[0008] A second object of the invention is a catalytic system based on at least one metallocene of formula (IIIa) or (IIIb) and a diorganomagnesium compound according to the invention as a co-catalyst, {P(Cp 1< )(Cp 2< )Y} (IIIa) Cp 3< Cp 4< Y (IIIb) Y designating a group comprising an atom of a rare earth, Cp 1< , Cp 2< , Cp 3< and Cp 4< , identical or different, being chosen from the group consisting of fluorenyl groups, cyclopentadienyl groups and indenyl groups, the groups being substituted or unsubstituted, P being a group bridging the two groups Cp 1< and Cp 2< , and comprising an atom of silicon or carbon.

[0009] A third object of the invention is a process for preparing a polymer which comprises the polymerization of a second monomer in the presence of a catalytic system according to the invention, the second monomer being ethylene or a mixture of ethylene and a comonomer, the comonomer being a 1,3-diene, an α-monoolefin or a mixture thereof.

[0010] A fourth object of the invention is a block polymer that can be obtained by the process according to the invention. Detailed description

[0011] 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).

[0012] The compounds mentioned in the description can be of fossil origin or bio-based. In the latter case, they may be partially or entirely derived 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 partially or entirely produced through a recycling process, or obtained from raw materials themselves derived from a recycling process.

[0013] The expression "based on" used to define the constituents of the catalytic system means the mixture of these constituents, or the product of the reaction of some or all of these constituents with each other.

[0014] The compound according to the invention, with formula (I), is hereinafter referred to as an asymmetric diorganomagnesium compound, since the two groups represented by the symbols RB< and RA< are different from each other. RB< -Mg-RA< (I)

[0015] The group represented by the symbol RA< is a polymer chain containing units of a first monomer chosen from the group of monomers consisting of 1,3-dienes, aromatic α-monolefins, and mixtures thereof. Suitable 1,3-dienes are those having from 4 to 20 carbon atoms. The 1,3-diene as the first monomer is preferably 1,3-butadiene, isoprene, or a mixture thereof. The aromatic α-monolefin as the first monomer is an α-monolefin with the formula CH₂=CH-Ar, where Ar represents an aromatic group, substituted or unsubstituted. The Ar group is preferably phenyl or aryl. The aromatic α-monolefin as the first monomer is preferably styrene or a styrene substituted with one or more alkyl groups, more preferably styrene. Preferably, RA< represents a homopolymer chain of 1,3-butadiene, isoprene or styrene or a copolymer chain of monomers selected from 1,3-butadiene, isoprene and styrene.

[0016] The polymer chain represented by the symbol RA< is also characterized by being a functional chain. It bears an amine function at its chain end. The amine function is a primary, secondary, or tertiary amine, preferably tertiary.

[0017] The group represented by the symbol RB< is characterized by a benzene ring substituted by a magnesium atom. Both carbon atoms of the benzene ring ortho to magnesium bear a substituent, either identical or different. Alternatively, one of the two carbon atoms of the benzene ring ortho to magnesium may bear a substituent, while the other carbon atom of the benzene ring ortho to magnesium may form a ring. The substituent is a methyl, an ethyl, or an isopropyl. If one of the two carbon atoms of the benzene ring ortho to magnesium is substituted by an isopropyl, the second carbon atom of the benzene ring ortho to magnesium is not substituted by an isopropyl. Preferably, the carbon atoms of the benzene ring ortho to magnesium are substituted by a methyl or an ethyl.More preferentially, the carbon atoms of the benzene ring ortho to magnesium are substituted by a methyl.

[0018] According to a preferred embodiment, the asymmetric diorganomagnesium compound corresponds to formula (II) in which RA< is a polymer chain as defined above, R1 and R5, 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, R1 and R5 represent a methyl group. Preferably, R2 and R4 represent a hydrogen atom.

[0019] According to a preferred variant, R1, R3, and R5 are identical. According to a more preferred variant, R2 and R4 represent hydrogen, and R1, R3, and R5 are identical. In a further preferred variant, R2 and R4 represent hydrogen, and R1, R3, and R5 represent methyl.

[0020] According to a preferred embodiment, the polymer chain represented by the symbol RA< is prepared by anionic polymerization.

[0021] The asymmetric diorganomagnesium compound according to the invention can be prepared by a process which comprises the following steps: the contacting of a living anionic polymer RA< Li with a halide of an organomagnesium compound of formula RB< -Mg-X, the reaction of the living anionic polymer and the halide, Let X be a halogen chosen from the group consisting of chlorine, fluorine, bromine, and iodine, with RB< and RA< being as defined previously. X is preferably a bromine atom or a chlorine atom. X is more preferably a bromine atom.

[0022] The living anionic polymer useful for the synthesis of the organometallic compound with the formula RA<Li is typically a polymer chain with a first end bearing an amine group and a second end bearing a carbanion. It generally results from the initiation and propagation reactions of a polymer chain in the anionic polymerization of the first monomer. 1,3-Dienes, aromatic α-monolefins, and mixtures thereof, which can be used as the first monomer, are well known to polymerize or copolymerize together anionically and to form living polymer chains or copolymers. The polymerization processes of these monomers are also well known and widely described.

[0023] In the initiation of the polymerization reaction, a lithium amide or an organolithium compound bearing an amine functional group is used as an initiator. Such initiators have been described, for example, in patents EP 0 590 490 B1 and EP 0 626 278 B1. Examples of lithium amides include lithium pyrrolidine amide and lithium hexamethyleneimine amide. Suitable organolithium compounds bearing an amine functional group include dimethylaminopropyllithium and 3-pyrrolidinopropyllithium. Advantageously, the initiator is lithium hexamethyleneimine amide, in which case the amine functional group at the end of the block copolymer is the hexamethyleneimino group. The initiator is used at a rate chosen according to the desired chain length of the polymer and can therefore vary considerably.

[0024] The living anionic polymer is thus obtained conventionally by anionic polymerization of the first monomer in a solvent, called the polymerization solvent. The polymerization solvent can be any hydrocarbon solvent known to be used in the polymerization of 1,3-diene and α-aromatic monomers. Preferably, the polymerization solvent is a hydrocarbon solvent, ideally an aliphatic one such as hexane, cyclohexane, or methylcyclohexane.

[0025] The polymerization solvent for the first monomer may include an additive to control the polymer chain microstructure and the rate of the polymerization reaction. This additive can be a polar agent such as an ether or a tertiary amine. The additive is most often used in small quantities, particularly to limit site deactivation reactions that propagate the anionic polymerization reaction. The amount of additive in the polymerization solvent, traditionally indexed to the amount of initiator used in the polymerization medium, is adjusted according to the desired polymer chain microstructure and therefore depends on the complexing power of the additive.

[0026] The ratio between the amount of solvent and the amount of first monomer required for the formation of the living polymer is determined by a person skilled in the art according to the desired viscosity of the living 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 living polymer 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.

[0027] The polymerization temperature for forming the living polymer can vary considerably. It is chosen based on factors such as the stability of the carbon-metal bond in the polymerization solvent, the relative rate coefficients of the initiation and propagation reactions, and the desired microstructure of the living polymer. Traditionally, it ranges from -20 to 100°C, preferably from 20 to 70°C.

[0028] Preferably, the living anionic polymer is a living polymer obtained by anionic polymerization of 1,3-butadiene, isoprene, styrene, or a mixture of two or all three of them. In other words, the first monomer is preferably 1,3-butadiene, isoprene, styrene, or a mixture of two or all three of them.

[0029] The living anionic polymer can be a homopolymer or a copolymer, in the case where the first monomer is a mixture of monomers. The copolymer can be random or block, since the insertion of monomers into the polymer chain can be controlled under known operating conditions of anionic polymerization processes. For example, it is known that the polarity of the polymerization solvent and the method of feeding the monomers into the anionic polymerization medium influence the relative incorporation of the monomers.

[0030] In the preparation of the asymmetric diorganomagnesium compound according to the invention, the contacting of the living anionic polymer with the halide of an organomagnesium compound is preferably achieved by adding a solution of the living anionic polymer RA< Li to a solution of the halide of an organomagnesium compound RB< -Mg-X. The solution of the living anionic polymer RA< Li is generally a solution in a hydrocarbon solvent, preferably aliphatic, such as n-hexane, cyclohexane, or methylcyclohexane. The solution of the halide of an organomagnesium compound RB< -Mg-X is generally a solution in an ether, preferably diethyl ether or dibutyl ether. The concentration of the living anionic polymer RA< Li is preferentially from 0.0001 to 1 mol of lithium equivalent / L, more preferably from 0.0005 to 0.2 mol of lithium equivalent / L, that of the solution of the organomagnesium RB< -Mg-X preferentially from 0.1 to 5 mol / L, more preferably from 0.1 to 3 mol / L.

[0031] The reaction between the living anionic polymer RA< Li and the halide of an organomagnesium compound RB< -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.

[0032] 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.

[0033] Once the asymmetric diorganomagnesium compound is formed, it is generally recovered in solution after filtration conducted under an inert and anhydrous atmosphere. The solution of the asymmetric diorganomagnesium compound is typically stored before use in airtight containers, for example, capped bottles, at a temperature between -25°C and 23°C.

[0034] Like any organomagnesium compound, the diorganomagnesium compound RB< -Mg-RA< useful for the purposes of the invention can be in the form of a monomeric entity (RB< -Mg-RA< ) 1 or in the form of a polymeric entity (RB< -Mg-RA< ) p, p being an integer greater than 1, in particular a dimer (RB< -Mg-RA< ) 2. Furthermore, whether in the form of a monomeric or polymeric entity, it can also be in the form of an entity coordinated to one or more molecules of a solvent, preferably an ether such as diethyl ether, tetrahydrofuran or methyltetrahydrofuran.

[0035] The asymmetric diorganomagnesium compound according to the invention is particularly intended for use as a co-catalyst in a catalytic system comprising an organometallic complex and useful for the polymerization or copolymerization of olefins or dienes. The organometallic complex is typically a rare-earth metallocene or hemimetallocene.

[0036] The asymmetric diorganomagnesium compound's role is to activate the organometallic complex in the polymerization reaction, particularly in the polymerization initiation reaction. It can replace the co-catalyst in the catalytic systems described, for example, in documents EP 1092731 A1, WO 2004035639 A1, WO 2005028526 A1, WO2007045223 A2, and WO2007045224 A2.

[0037] In particular, the asymmetric diorganomagnesium compound according to the invention is one of the essential constituents of a catalytic system, another object of the invention.

[0038] The catalytic system according to the invention therefore has as basic constituents the asymmetric diorganomagnesium compound according to the invention and a metallocene of formula (IIIa) or (IIIb) {P(Cp 1< )(Cp 2< )Y} (IIIa) Cp 3< Cp 4< Y (IIIb) Y designating a group comprising an atom of a rare earth, Cp 1< , Cp 2< , Cp 3< and Cp 4< , identical or different, being chosen from the group consisting of fluorenyl groups, cyclopentadienyl groups and indenyl groups, the groups being substituted or unsubstituted, P being a group bridging the two groups Cp 1< and Cp 2< , and comprising an atom of silicon or carbon.

[0039] It is worth recalling that rare earths are metals and refer to the elements scandium, yttrium and lanthanides whose atomic number varies from 57 to 71.

[0040] According to a first embodiment of the invention, the metallocene used as a basic constituent in the catalytic system according to the invention corresponds to the formula (IIIa) {P(Cp 1< )(Cp 2< )Y} (IIIa) in which Y denotes a group containing a rare earth atom, Cp 1< and Cp 2<, identical or different, are chosen from the group consisting of fluorenyl groups, cyclopentadienyl groups and indenyl groups, the groups being substituted or unsubstituted, P is a group bridging the two groups Cp 1< and Cp 2<, and comprising a silicon or carbon atom.

[0041] According to a second embodiment of the invention, the metallocene used as a basic constituent in the catalytic system according to the invention corresponds to the formula (IIIb) Cp 3< Cp 4< Y (IIIb) in which Y designates a group containing a rare earth atom, Cp 3< and Cp 4< , identical or different, are chosen from the group consisting of fluorenyl groups, cyclopentadienyl groups and indenyl groups, the groups being substituted or unsubstituted.

[0042] Examples of substituted cyclopentadienyl, fluorenyl, and indenyl groups include those substituted by alkyl radicals with 1 to 6 carbon atoms, aryl radicals with 6 to 12 carbon atoms, or trialkylsilyl radicals such as SiMe3. The choice of radicals is also guided by the accessibility of the corresponding molecules, namely the substituted cyclopentadienes, fluorenes, and indenes, because these are either commercially available or easily synthesized.

[0043] Examples of substituted fluorenyl groups include those substituted at positions 2,7, 3, or 6, particularly 2,7-ditertiobutyl-fluorenyl and 3,6-ditertiobutyl-fluorenyl. 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.

[0044] 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, most notably the tetramethylcyclopentadienyl group. Position 2 (or 5) refers to the position of the carbon atom adjacent to the carbon atom to which the P-bridge is attached, as shown in the diagram below.

[0045] Examples of substituted indenyl groups include those substituted at position 2, particularly 2-methylindenyl and 2-phenylindenyl. Position 2 refers to the position of the carbon atom adjacent to the carbon atom to which the P-bridge is attached, as shown in the diagram below.

[0046] Preferably, the metallocene is of formula (IIIa).

[0047] According to a preferred embodiment of the invention, Cp1 and Cp2 are identical and are selected from the group consisting of substituted fluorenyl groups and the unsubstituted fluorenyl group of formula C13H8. The catalytic system according to this preferred embodiment has the particularity of leading to butadiene and ethylene copolymers which, in addition to ethylene monomer units and butadiene units, comprise cyclic units, 1,2-cyclohexane units of the following formula:

[0048] The cyclic units result from a specific insertion of ethylene and 1,3-butadiene monomers into the polymer chain, in addition to the conventional ethylene and 1,3-butadiene units, namely -(CH₂-CH₂)-, -(CH₂-CH=CH-CH₂)-, and -(CH₂-CH(C=CH₂))-. The mechanism for obtaining such a microstructure is described, for example, in Macromolecules 2009, 42, 3774-3779.

[0049] Advantageously, Cp 1< and Cp 2< are identical and each represent an unsubstituted fluorenyl group of formula C 13 H 8, represented by the symbol Flu.

[0050] According to a preferred embodiment of the invention, the symbol Y represents the Met-G group, with Met denoting the rare-earth atom and G denoting a group comprising the borohydride motif BH4 or a halogen atom selected from the group consisting of chlorine, fluorine, bromine, and iodine. Advantageously, G denotes a chlorine atom or the group of formula (IV): (BH4)(1+y)-Ly-Nx(IV) in which L represents an alkali metal chosen from the group consisting of lithium, sodium and potassium, N represents a molecule of an ether, x, an integer or not, is equal to or greater than 0, y, an integer, is equal to or greater than 0.

[0051] Most advantageously, G denotes the group of formula (IV).

[0052] Any ether that has the ability to complex alkali metal is suitable, especially diethyl ether and tetrahydrofuran.

[0053] According to any one of the embodiments of the invention, the metal of the metallocene useful for the need of the invention, in this case the rare earth, is preferably a lanthanide whose atomic number ranges from 57 to 71, more preferably neodymium, Nd, in which case the symbol Met in the group Met-G preferentially designates a lanthanide atom whose atomic number ranges from 57 to 71, more preferably a neodymium atom.

[0054] The P-bridge connecting the Cp1< and Cp2< groups preferably corresponds to the formula ZR1<R2<, in which Z represents a silicon or carbon atom, and R1< and R2<, identical or different, each represent an alkyl group comprising from 1 to 20 carbon atoms, preferably a methyl. In the formula ZR1<R2<, Z advantageously represents a silicon atom, Si.

[0055] The metallocene used in the synthesis of 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 patent applications WO 2007054224 or WO 2007054223. The metallocene can be prepared conventionally by a process similar to that described in patent applications WO 2007054224 or WO 2007054223, specifically by reacting, under inert and anhydrous conditions, the salt of an alkali metal of the ligand with a rare-earth borohydride 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 metallocene is separated from the reaction byproducts by techniques known to those skilled in the art, such as filtration or precipitation in a second solvent.The metallocene is ultimately dried and insulated in solid form.

[0056] According to a particularly preferred embodiment, the metallocene has the formula (III-1), (III-2), (III-3), (III-4) or (III-5): [Me 2 Si(Flu) 2 Nd(µ-BH 4 ) 2 Li(THF)] (III-1) [{Me 2 SiFlu 2 Nd(µ-BH 4 ) 2 Li(THF)} 2 ] (III-2) [Me 2 SiFlu 2 Nd(µ-BH 4 )(THF)] (III-3) [{Me 2 SiFlu 2 Nd(µ-BH 4 )(THF)} 2 ] (III-4) [Me 2 SiFlu 2 Nd(µ-BH 4 )] (III-5) where Flu represents the C 13 H 8 group.

[0057] The catalytic system according to the invention can be prepared conventionally by a process analogous to that described in patent application WO 2007054224 or WO 2007054223. For example, the asymmetric diorganomagnesium compound 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 usually prepared in a hydrocarbon solvent, aliphatic such as methylcyclohexane or aromatic such as toluene.Generally, after its synthesis, the catalytic system is used as is in the polymer synthesis process according to the invention.

[0058] Like all syntheses carried out in the presence of organometallic compounds, the synthesis of the metallocene, the synthesis of the asymmetric diorganomagnesium compound, and the synthesis of the catalytic system take place under anhydrous conditions in an inert atmosphere. Typically, the reactions are conducted using solvents and anhydrous compounds under anhydrous nitrogen or argon. In particular, the solvents are generally purified, for example, by known methods such as distillation, treatment on alumina columns, bubbling with an inert gas like nitrogen or argon, or treatment with an organometallic compound such as an organolithium, organomagnesium, or organoaluminum compound.

[0059] 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 preferably ranges from 0.0001 to 0.2 mol / L, and more preferably from 0.001 to 0.03 mol / L.

[0060] The catalytic system according to the invention is intended for use in a process for synthesizing block copolymers and amine functionals, particularly elastomers, for use in rubber compositions, for example, for tires. The use of the catalytic system according to the invention makes it possible to prepare, by catalytic polymerization with strong catalytic activity, ethylene- and 1,3-diene or α-monolefin-based polymers that are both block copolymers and chain-end amine functionals.

[0061] The process for synthesizing block and amine functional copolymers, another object of the invention, comprises a step of polymerizing a second monomer in the presence of the conforming catalytic system. The second monomer is ethylene or a mixture of ethylene and a comonomer, the comonomer being a 1,3-diene, an α-monoolefin, or a mixture thereof. An α-monoolefin is defined as an α-olefin having a single carbon-carbon double bond, double bonds in aromatic compounds not being taken into account. For example, styrene is considered an α-monoolefin. Preferably, the comonomer is 1,3-butadiene, isoprene, or a mixture of two or all three of the comonomers 1,3-butadiene, isoprene, and styrene.

[0062] Since the process involves the polymerization of a monomer, referred to as the second monomer, in the presence of a catalytic system comprising a co-catalyst consisting of a polymer chain RAc, the polymer chain RAc and the polymer chain resulting from the polymerization of the second monomer constitute the block copolymer synthesized by the process according to the invention. The polymers synthesized by the process according to the invention are therefore block, diblock, or multiblock copolymers. Indeed, the polymer chain RAc can be a homopolymer, a block copolymer, or a random copolymer. The polymer chain resulting from the polymerization of the second monomer can be a random copolymer or a block copolymer when the second monomer is a mixture of monomers.

[0063] Preferably, the second monomer is ethylene or a mixture of a 1,3-diene and ethylene, the 1,3-diene as comonomer preferably being 1,3-butadiene, isoprene, or a mixture thereof. Depending on the microstructure and length of the polymer chains prepared by the process according to the invention, the polymer can be an elastomer.

[0064] The polymerization of the second monomer is preferably carried out in solution, either continuously or batchwise. The polymerization solvent can be a hydrocarbon, aromatic, or aliphatic solvent. Examples of polymerization solvents include toluene and methylcyclohexane. The second monomer can be introduced into the reactor containing the polymerization solvent and the catalytic system, or conversely, the catalytic system can be introduced into the reactor containing the polymerization solvent and the second monomer. The second monomer and the catalytic system can be introduced simultaneously into the reactor containing the polymerization solvent, particularly in the case of continuous polymerization. Polymerization is typically carried out under anhydrous conditions and in the absence of oxygen, possibly with the addition of an inert gas.The polymerization temperature generally varies between 40 and 150°C, preferably between 40 and 120°C. It is adjusted according to the second monomer to be polymerized. If the second monomer is a mixture of monomers containing ethylene, the copolymerization is preferably carried out at constant monomer pressure. If the second monomer is a mixture of monomers, the second block can be either random or block-type, depending on the respective monomer feeding method.

[0065] In cases where the polymerization of a second monomer is a mixture of ethylene and 1,3-diene in a polymerization reactor, a continuous addition of ethylene and 1,3-diene can be 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 and 1,3-diene.

[0066] Once the desired conversion rate of the second monomer polymerization reaction is reached, the polymerization reaction is stopped by a termination reaction. Typically, the polymerization reaction is followed by a reaction with a protic compound to stop the polymerization reaction, such as an alcohol, typically methanol or ethanol, or with a functionalizing agent to functionalize the polymer. The functionalizing agent is typically a compound known to react with a compound containing a carbon-magnesium bond. Suitable functionalizing agents include amines, dihalogens, ketones, esters, and alkoxysilanes, such as iodine and 4,4'-bis(diethylamino)benzophenone.The block copolymer can be recovered, in particular by separating it from the reaction medium, for example by coagulating it in a solvent causing its coagulation or by removing the polymerization solvent and any residual monomer under reduced pressure or under the effect of steam entrainment (stripping operation).

[0067] The block and amine functional copolymers obtainable by the process according to the invention are essentially characterized by comprising two blocks. One of the blocks, referred to as the first block, is a polymer chain of a first monomer selected from 1,3-dienes, aromatic α-monolefins, and mixtures thereof. The second block is a polymer chain of a second monomer selected from ethylene and mixtures of ethylene and a comonomer, the comonomer being a 1,3-diene, an α-monoolefin, or a mixture thereof. The amine functional group at the end of the polymer according to the invention is borne by the first block. The amine functional group is preferably a tertiary amine, more preferably the hexamethyleneimno group.

[0068] In the case where the second block is a copolymer of ethylene and a comonomer, the ethylene units of formula -(CH2-CH2)- present in the second block preferentially represent more than 50% by moles of the monomer units of the second block.

[0069] The polymers according to the invention are prepared with high catalytic activity, making their preparation attractive for at least two reasons. The first is the catalytic cost of the polymers according to the invention, which is significantly lower than that of known non-functional block copolymers. The second is the content of catalytic residues, which is also much lower in the polymers according to the invention than in known non-functional block copolymers.

[0070] The aforementioned features of the present invention, as well as others, will be better understood upon reading the following description of examples of embodiments of the invention, given by way of illustration and not limitation. Examples Preparation of 2-mesitylmagnesium bromide:

[0071] The toluene and 2-methyltetrahydrofuran (MeTHF) used in the syntheses were distilled over sodium / benzophenone.

[0072] 4.15 g (170 mmol, 3.4 equivalents) of magnesium are introduced into a 200 mL round-bottom flask fitted with a magnetic olive in a glove box. Approximately 30 mg of diiodine (0.12 mmol, 0.003 equivalents) are added to the magnesium. The flask is fitted with a 100 mL inert dropping funnel. 50 mL of MeTHF are introduced into the dropping funnel, and 10 mL are immediately dropped onto the magnesium while stirring. 7.65 mL of degassed and activated molecular sieve-dried 2-bromomesitylene (50 mmol, 1 equivalent) is introduced into the flask while stirring using the dropping funnel. The 2-bromomesitylene solution is added dropwise to the magnesium over 1 h, with exothermic reaction control. Stirring is maintained for 12 h at 20 °C. At the end of the reaction, the solution is transferred to a filtering cannula in a second inert 200 mL flask. This solution is concentrated under vacuum and then diluted in 71 mL of toluene. The concentration of 2-mesitylmagnesium bromide is estimated to be 0.50 mol L -1< (M). Preparation of the lithium hexamethyleneimide initiator: HMNLi

[0073] 384 mL of methylcyclohexane (MCH) from the solvent fountain are placed in a 750 mL Steinie bottle. 4.75 mL of hexamethyleneimine (HMN) (42 mmol, 1 equivalent) are diluted in the bottle containing the MCH. The contents of the bottle are degassed for 10 min under nitrogen. 30.5 mL of 1.38 M BuLi (42 mmol, 1 equivalent) are introduced into the bottle. The reaction time is estimated at 1 hour. The concentration of active Li determined by the Gilman method is 0.087 M.

[0074] Six elastomers according to the invention, which are block copolymers and bear an amine function, were prepared according to the operating procedures of tests 1 to 6 described in examples 1, 2 and 3.

[0075] Example 1 according to the invention: preparation of two polymers with amine functional blocks, the first blocks being a polybutadiene, the second blocks being a random copolymer of ethylene and 1,3-butadiene, the amine function being hexamethyleneimine. Preparation of the first block:

[0076] Approximately 86 mL of methylcyclohexane are introduced into two 250 mL Steinie bottles. The contents of the bottles are degassed under nitrogen for 10 minutes. 82 mL of methylcyclohexane are thus recovered from each bottle. 13.5 mL (9 g) of butadiene is introduced by syringe into bottles for test 1, and 2.7 mL (1.8 g) is introduced into bottles for test 2. 10 mL of 0.087 M (0.87 mmol) HMNLi solution is added to each bottle. The bottles are shaken in a water bath at 53 °C for approximately 2 hours. Preparation of the second block: For each trial 1 and 2, the procedure is as follows:

[0077] 2.4 mL (1.2 mmol, 1.4 equivalents) of 2-(mesitylmagnesium) bromide are introduced into the bottles (test 1: PB 10000 -Mg or test 2: PB2000 -Mg). A white precipitate forms (LiBr salt).

[0078] 230 mL of methylcyclohexane (MCH) are introduced into a 750 mL Steinie bottle. The contents of the bottle are degassed under nitrogen for approximately ten minutes. 220 mL of methylcyclohexane are thus recovered. 46 mg (72 µmol neodymium) of metallocene {(Me₂Si(C₁₃H₈)₂)Nd(BH₄)[(BH₄)Li(THF)]}₂ are weighed into a 250 mL Steinie bottle in a glove box. 0.6 mL (0.3 mmol) of 2-mesitylmagnesium bromide is introduced into the 750 mL bottle to neutralize impurities from the methylcyclohexane. Approximately 1 / 3 of the contents of the 750 mL bottle is transferred into the 250 mL bottle containing the metallocene using a double-needle system.

[0079] Half the contents of the 750 mL bottle containing methylcyclohexane are introduced into the inert reactor under stirring (400 rpm) at 77 °C. The contents of the bottle containing PB 10000-Mg or P B2000-Mg are transferred to the reactor after returning to room temperature (23 °C). Then, the contents of the 250 mL bottle containing the neodymium complex are transferred to the reactor, followed successively by the remaining methylcyclohexane from the 750 mL bottle. The Mg / Nd molar ratio is 21. The reactor is degassed under vacuum until gas bubbles form, then pressurized to 3 bar with an 80 / 20 ethylene / butadiene mixture (molar percentage).

[0080] When the ballast pressure reaches the pressure drop corresponding to 9 g of monomers, the reactor is degassed with 3 vent / nitrogen cycles. Two equivalents of a 0.2 mol / L 4,4'-bis(diethylamino)benzophenone (DEAB) solution in toluene (3.0 mmol), previously introduced into an inert 250 mL Steinie bottle, are introduced into the reactor.

[0081] Agitation is maintained for 1 hour, then the heating is switched off and agitation stopped. The polymerization medium is deactivated with a few mL of ethanol, then emptied into an aluminum tray and dried under vacuum at 50 °C in an oven for 24 h.

[0082] Approximately 2 g of polymer are solubilized in 20 mL of MCH, then precipitated in approximately 150 mL of acetone. This operation is repeated three times to wash the polymer.

[0083] The washed, dry polymer is recovered for analysis.

[0084] Example 2 according to the invention: preparation of two copolymers with amine functional blocks, the first blocks being a polybutadiene, the second blocks being a random copolymer of ethylene and 1,3-butadiene, the amine function being hexamethyleneimine: Preparation of the first block:

[0085] Approximately 86 mL of MCH are introduced into two 250 mL Steinie bottles. The contents of the bottles are degassed under nitrogen for 10 minutes. 82 mL of MCH are thus recovered from each bottle. 13.5 mL (9 g) of butadiene are introduced by syringe into the bottles for tests 3 and 4.

[0086] 0.7 mL of ETE (Ethyl tetrahydrofurfuryl ether) at 0.1 M in methylcyclohexane (0.07 mmol) are introduced into test bottle 3 and 1.0 mL of TMEDA (N,N,N',N'-tetramethylethylenediamine) at 0.5 M in methylcyclohexane (0.5 mmol) are introduced into test bottle 4.

[0087] 10 mL of 0.087 M (0.87 mmol) HMNLi solution are added to each bottle. The bottles are shaken in a water bath at 53 °C for approximately 1 hour. Preparation of the second block:

[0088] The procedure is identical to that of example 1.

[0089] Example 3 according to the invention: preparation of two copolymers with amine functional blocks, the first blocks being a statistical copolymer of styrene and 1,-butadiene, the second blocks being a statistical copolymer of ethylene and 1,3-butadiene, the amine function being hexamethyleneimine: Preparation of the first block:

[0090] Approximately 86 mL of MCH are introduced into four 250 mL Steinie bottles. The contents of the bottles are degassed under nitrogen for 10 minutes. 82 mL of MCH are thus recovered from each bottle. 10.2 mL (6.75 g) of butadiene and 2.5 mL (2.25 g) of styrene are introduced by syringe into the bottles for tests 5 and 6.

[0091] 0.7 mL of ETE (Ethyl tetrahydrofurfuryl ether) at 0.1 M in methylcyclohexane (0.07 mmol) are introduced into test 5 and 1.0 mL of TMEDA (N,N,N',N'-tetramethylethylenediamine) 0.5 M (0.5 mmol) are introduced into test 6.

[0092] 10 mL of the prepared HMNLi [0.087] (0.87 mmol) solution are added to each of the bottles. The bottles are shaken in a water bath at 53 °C for approximately 1 hour. Preparation of the second block:

[0093] The procedure is identical to that of example 1.

[0094] Example 4 not in accordance with the invention: preparation of a copolymer with functional amine blocks by non-catalytic polymerization, the first block being a polybutadiene, the second block being a polyethylene. Preparation of the first block:

[0095] Approximately 300 mL of toluene is introduced into a 750 mL Steinie bottle. The contents of the bottle are degassed under nitrogen for 10 minutes. 1 g of butadiene is introduced into the bottle using a syringe. 1 mL of 0.1 M (0.1 mmol) HMNLi solution is added to the bottle and shaken in a 60 °C water bath for 1 hour and 44 minutes. Preparation of the second block:

[0096] Transfer the entire volume of the solution containing the first block, using a double-needle system, into a 750 mL bottle containing 62 mg (96.9 µmol neodymium) of metallocene {(Me₂Si(C₁₃H₈)₂)Nd(BH₄)[(BH₄)Li(THF)]}₂ to activate the neodymium complex. The bottle is then enriched with ethylene to a pressure of approximately 3 bar. The bottle is then maintained at 60°C for 1 hour and 20 minutes.

[0097] The polymerization medium is deactivated with a few mL of ethanol, then emptied into an aluminum tray and dried under vacuum at 50 °C in an oven for 24 h. 1.25 g of polymer are recovered (test 7).

[0098] The polymers were characterized by high amino weight SEC analysis and 1<H / 13<C NMR to determine their number-average molar mass Mn and their microstructure respectively. SEC Method:

[0099] Size exclusion chromatography (SEC) allows the fractionation of polymer chains in a solvent according to their hydrodynamic volume. Like any chromatographic system, the technique is based on the elution of a solute (the polymer) through a column containing a stationary phase. The system consists, in this order, of a solvent reservoir, a pumping system, an injector, a set of columns, and detectors. The measurement chain is equipped with a Waters Alliance e2695 module and a Waters fRI410 refractometer.

[0100] The mobile phase is eluted at a flow rate of 1 mL / min. The polymer is solubilized in THF in the presence of 1 wt% diisopropylamine and 1 wt% triethylamine at a concentration of 1 g / L. A volume of 100 µL is injected through a set of three size-exclusion chromatography columns. AGILENT(MIXED B LS). The columns are thermostated in an oven at 35°C. The stationary phase of the columns is based on a divinylbenzene polystyrene gel with controlled porosity. The polymer chains are separated according to the hydrodynamic volume they occupy when solubilized in the solvent. The larger the volume, the less accessible the column pores are to them, and the shorter their elution time. Detection is performed by a refractometer (RI) thermostated at 35°C. Each elution volume is associated with a mass via Moore calibration (certified standard conversion: standard polystyrenes (peak molar masses)). M p: 1620 to 2,570,000 g mol⁻¹ (from Polymer Standard Service, Mainz). WATERS: EMPOWER software was used for data acquisition and analysis. This allowed for the determination of number-average molar masses (Mn), mass-average molar masses (Mw), and dispersity (D = Mw / Mn). 1H NMR method:

[0101] Nuclear magnetic resonance (NMR) 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 1,2-dichlorobenzene d4. Calibration was performed on the protonated impurity of 1,2-dichlorobenzene at 7.20 ppm using 1H NMR. The quantitative 1H NMR experiment employed a single 30° pulse sequence with a 5-second repetition interval between acquisitions.

[0102] The chemical shift between 5.36 and 5.10 ppm is attributed to the 1.4 units of butadiene, the signal between 5.63 and 5.36 ppm is attributed to the 1.2 units of butadiene, and the signal at 1.18 ppm is attributed to ethylene units.

[0103] The results are shown in Table 1. The functionalization of the block copolymers achieved by the initiation reaction with the initiator HMNLi and by the termination reaction with the modifying agent DEAB is also demonstrated by NMR analysis: Table 2 summarizes the chemical shifts in ppm of the signals for the block copolymers from tests 1 and 5. The catalytic activity of the polymers according to the invention (tests 1 to 6) was calculated and is shown in Table 3. The catalytic activity of the polymer obtained by non-catalytic polymerization (test 7) ​​was also calculated for comparison. [Table 1] Essay Mn g / mol Ð Ethylene / butadiene / styrene (mol%) 1 21 860 1.26 60.6 / 39.4 / 0 2 23 640 1,71 77.8 / 22.2 / 0 3 21 790 1.20 59.9 / 40.1 / 0 4 23 790 1.37 60.1 / 39.9 / 0 5 22 310 1.24 62.0 / 35.5 / 2.8 6 21 780 1.49 59.3 / 37.6 / 3.1 [Table 2] Essay HMNLi Functionality ATM functionality 1 3.13 (br, 2H, -CH2-HMN), 2.61 (br, 4H, HMN), 7.24 (br, 4H), 6.59 (d, J = 8.3 Hz, 4H), 3.32 (quad, J = 7.4 Hz, 8H), 1.13 (t, J = 7.0 Hz, 12H) 5 3.13 (br, 2H, -CH2-HMN, 2.61 (br, 4H, HMN, 1.60 (br, 8H, HMN), 6.58 (br, 4H), 3.31 (br, 8H), 1.14 (br, 12H) HMN representing the hexamethyleneimino radical, d: doublet; t: triplet; quad: quadruplet; br: broad, J: coupling constant. [Table 3] Essay Catalytic activity (kg mol -1 < h -1 < ) 1 110 2 120 3 110 4 55 5 110 6 55 7 1.94

[0104] The results show that using the diorganomagnesium compound according to the invention as a co-catalyst in a catalytic system comprising a rare-earth metallocene allows the preparation of novel chain-end amine block copolymers with strong catalytic activity. The polymers thus prepared are characterized by a first block of a 1,3-diene and / or an aromatic α-monolefin bearing the amine function and a second block containing ethylene units, the second block also potentially bearing a functional group at its end. The presence of the chain-end amine function and the respective compositions of the blocks make it possible to combine, in a single polymer, the properties of a polymer bearing a chain-end amine function with those of a block copolymer formed from a first block of a 1,3-diene and / or an aromatic α-monolefin and a second block containing ethylene units.Furthermore, the catalytic cost of the polymers according to the invention and their content of rare earth catalytic residues are relatively low.

Claims

1. Diorganomagnesium compound of formula (I)         RB-Mg-RA     (I) RA being different from RB, RA being a polymer chain of a first monomer chosen from the group of monomers consisting of 1,3-dienes, aromatic α-monoolefins and mixtures thereof, the polymer chain having a first end bonded to the magnesium atom and a second end bearing an amine function, RB comprising a benzene nucleus substituted with a magnesium atom, one of the carbon atoms of the benzene nucleus ortho to the magnesium being substituted with a methyl, an ethyl, an isopropyl or forming a ring with the carbon atom which is its closest neighbour and which is meta to the magnesium, the other carbon atom of the benzene nucleus ortho to the magnesium being substituted with a methyl, an ethyl or an isopropyl, on condition that if one of the 2 ortho carbon atoms is substituted with an isopropyl, the second ortho carbon atom is not substituted with an isopropyl.

2. Diorganomagnesium compound according to Claim 1, in which the diorganomagnesium compound is of formula (II) R1 and R5, which may be identical or different, represent a methyl or an ethyl, preferably a methyl, R2, R3 and R4, which may be identical or different, being a hydrogen atom or an alkyl, RA being defined according to Claim 1.

3. Diorganomagnesium compound according to either one of Claims 1 to 2, in which RA is a 1,3-butadiene, isoprene or styrene homopolymer chain or a copolymer chain of monomers chosen from 1,3-butadiene, isoprene and styrene.

4. Diorganomagnesium compound according to any one of Claims 1 to 3, in which the amine function is a tertiary amine.

5. Catalytic system based at least: - on a metallocene of formula (IIIa) or (IIIb), - on a diorganomagnesium compound as cocatalyst,         {P(Cp1)(Cp2)Y}     (IIIa)         Cp3Cp4Y     (IIIb) Y denoting a group including a rare-earth metal atom, Cp1, Cp2, Cp3 and Cp4, which may be identical or different, being chosen from the group consisting of fluorenyl groups, cyclopentadienyl groups and indenyl groups, the groups being substituted or unsubstituted, P being a group bridging the two groups Cp1 and Cp2 and comprising a silicon or carbon atom, the diorganomagnesium compound being a diorganomagnesium compound defined in any one of Claims 1 to 4.

6. Catalytic system according to Claim 5, in which Cp1 and Cp2 are identical and are chosen from the group consisting of substituted fluorenyl groups and the unsubstituted fluorenyl group of formula C13H8.

7. Catalytic system according to either one of Claims 5 to 6, in which the rare-earth metal is a lanthanide the atomic number of which ranges from 57 to 71, preferably neodymium.

8. Catalytic system according to any one of Claims 5 to 7, in which the bridge P corresponds to the formula ZR1R2, Z representing a silicon or carbon atom and R1 and R2, which may be identical or different, each representing an alkyl group comprising from 1 to 20 carbon atoms, preferably a methyl.

9. Catalytic system according to Claim 8, in which Z is Si.

10. Catalytic system according to any one of Claims 5 to 9, in which the symbol Y represents the group Met-G, with Met denoting the rare-earth metal atom and G denoting a group comprising the borohydride BH4 unit or denoting a halogen atom chosen from the group consisting of chlorine, fluorine, bromine and iodine.

11. Catalytic system according to Claim 10, in which G denotes a chlorine atom or the group of formula (IV)         (BH4)(1+y)-Ly-Nx     (IV) in which L represents an alkali metal chosen from the group consisting of lithium, sodium and potassium, N represents a molecule of an ether, preferably diethyl ether or tetrahydrofuran, x, which may or may not be an integer, is greater than or equal to 0, y, which is an integer, is greater than or equal to 0.

12. Process for preparing a polymer, which comprises polymerizing a second monomer in the presence of a catalytic system defined in any one of Claims 5 to 11, the second monomer being ethylene or a mixture of ethylene and a comonomer, the comonomer being a 1,3-diene, an α-monoolefin or a mixture thereof.

13. Process for preparing a polymer according to Claim 12, in which the comonomer is 1,3-butadiene, isoprene or a mixture of two or three comonomers 1,3-butadiene, isoprene and styrene.

14. Process for preparing a polymer according to either one of Claims 12 to 13, in which the polymerization of the second monomer is followed by a reaction with a protic compound or with a functionalizing agent.