ethylene-rich diene tri-block polymers having statistical blocks and two terminal polyethylene blocks

Abstract

This invention relates to a triblock polymer having the formula B-A-B, wherein the symbol A represents a block referred to as the central block, which is a statistical copolymer comprising 1,3-diene units and greater than 50 mol% ethylene units, and the symbol B represents a block referred to as a terminal block, which is composed of polyethylene with a melting point above 90°C and a number-average molar mass greater than or equal to 2000 g / mol and less than or equal to 10000 g / mol. Compared with statistical copolymers based on ethylene and 1,3-diene having the same microstructure, this triblock polymer exhibits improved rheological properties without altering its mechanical, kinetic, or thermal properties.

Description

Technical Field

[0001] The field of this invention is the field of diene copolymers rich in ethylene units. Background Technology

[0002] It has been shown that statistical copolymers based on ethylene and 1,3-diene and rich in ethylene units have favorable stiffness, hysteresis, abrasion, and adhesion properties. For example, reference can be made to patent applications WO 2014 / 114607 A1, WO 2016 / 012259 A1, and WO 2016 / 087248 A1.

[0003] Another advantage of these copolymers is the use of ethylene, a common commercially available monomer that can be obtained through fossil or biological pathways. Yet another advantage is the presence of ethylene units along the polymer backbone, which are much less sensitive to oxidative or thermal oxidative degradation mechanisms than diene units, resulting in better material stability and lifespan.

[0004] Controlling the rheological properties of polymers is a key parameter for polymer industrialization and use. The manufacture of articles made wholly or partially of polymers typically involves various operations such as kneading, extrusion, and molding, during which the polymer is subjected to stresses across a wide range of frequencies. The rheological properties of the polymer must be adapted to these diverse operations to meet the quality standards of the manufactured articles and the productivity standards of the production line. In particular, high viscosity at low-frequency strains is desirable to limit polymer flow phenomena. For example, solutions for increasing viscosity at low shear rates without affecting viscosity at higher shear rates are described in WO 99 / 10421 A1. These include crosslinking the polymer through free radical reactions or modifying it using multifunctional coupling agents capable of intercalating into CH bonds. Grafting associative functional groups onto the polymer is also a solution for improving polymer rheological properties, as described in patent application WO 2008 / 099125 A1. Summary of the Invention

[0005] The applicant has discovered that the rheological properties of statistical copolymers based on ethylene and 1,3-diene and rich in ethylene units can be improved without altering their mechanical, kinetic, or thermal properties.

[0006] Therefore, the first subject of the present invention is a triblock polymer of formula BAB, wherein the symbol A represents a “central” block, which is a statistical copolymer comprising 1,3-diene units and more than 50 mol% ethylene units, and the symbols B each represent “end” blocks, which are polyethylenes with a melting point above 90°C and a number-average molar mass greater than or equal to 2000 g / mol and less than or equal to 10000 g / mol, and the content of ethylene units in the central block is expressed as a molar percentage relative to the number of moles of monomer units constituting the central block.

[0007] The second subject of the invention is a composition comprising a triblock polymer according to the invention and another component.

[0008] The third subject of the invention is a method for synthesizing a triblock polymer according to the invention.

[0009] illustrate

[0010] Any numerical interval expressed as “between a and b” represents a range of values ​​greater than “a” and less than “b” (i.e., excluding the endpoints a and b), while any numerical interval expressed as “a to b” means a range of values ​​extending from “a” to “b” (i.e., including the strict endpoints a and b).

[0011] The expression “based on” used to define the components of a catalytic system or composition is understood to mean a mixture of these components, or the product of some or all of these components reacting with each other.

[0012] Unless otherwise stated, the content of units resulting from monomer insertion into the copolymer is expressed as a molar percentage relative to all monomer units constituting the polymer.

[0013] The compounds mentioned in the specification may be fossil-derived or bio-based. In the case of bio-based compounds, they may be derived partly or entirely from biomass, or obtained from renewable raw materials derived from biomass. Similarly, the compounds mentioned may also be obtained by recycling used materials, i.e., they may come partly or entirely from the recycling process, or from raw materials that themselves come from the recycling process.

[0014] The polymer according to the invention is a triblock of formula BAB. The block A, referred to as the central block, represents a block that is a statistical copolymer comprising ethylene units and 1,3-diene units, meaning that the constituent monomer units of the central block are statistically distributed within the central block, due to the statistical bonding of the monomers into the growing polymer chain. The other two blocks, represented by B, are each homopolymer polyethylene.

[0015] In a known manner, the term "ethylene unit" refers to a unit with a -(CH2-CH2)- moiety. The ethylene units present in block A, referred to as the central block, constitute more than 50 molar percent of the units constituting the central block. In this patent application, the content of ethylene units in the central block, i.e., the number of moles of ethylene units in the central block, is expressed as a molar percentage relative to the number of moles of the monomeric units constituting the central block.

[0016] According to any embodiment of the invention, the central block is preferably a statistical copolymer of ethylene and 1,3-diene, in which the monomer units of the central block are monomer units generated by copolymerization of ethylene and 1,3-diene and are statistically distributed in the central block.

[0017] According to the present invention, the 1,3-diene constituting the monomer unit of the central block is a single compound (i.e., a single 1,3-diene) or a mixture of 1,3-dienes with different chemical structures. The 1,3-diene is preferably 1,3-butadiene, isoprene, or a mixture of 1,3-dienes, wherein one of the 1,3-diene mixtures is 1,3-butadiene. More preferably, the 1,3-diene is 1,3-butadiene. Very preferably, the central block is a statistical copolymer of ethylene and 1,3-butadiene.

[0018] In a known manner, in the case of a substituted diene (such as isoprene), 1,3-diene can be inserted into an extended polymer chain via 1,4 or 2,1 or 3,4 insertion to form 1,4-configured, 1,2-configured, or 3,4-configured 1,3-diene units, respectively. Preferably, the 1,2-configured and 3,4-configured 1,3-diene units account for more than 50 moles of the total 1,3-diene units.

[0019] According to one embodiment of the invention, the central block comprises a 1,4-configured 1,3-diene unit, preferably a trans-1,4-configured 1,3-diene unit. Preferably, the trans-1,4-configured 1,3-diene unit accounts for more than 50 mol% of the 1,4-configured 1,3-diene unit. More preferably, the trans-1,4-configured 1,3-diene unit accounts for 100 mol% of the 1,4-configured 1,3-diene unit.

[0020] According to a particularly preferred embodiment of the invention, the central block comprises a 1,3-diene unit comprising more than 50 mol% of 1,2 or 3,4-configured units, with the balance of 100% of the 1,3-diene units being trans-1,4-configured units.

[0021] According to another particularly preferred embodiment of the invention, especially when the 1,3-diene is 1,3-butadiene or a mixture of 1,3-dienes in which one is 1,3-butadiene, the central block further comprises a 1,2-cyclohexanediyl unit or a 1,4-cyclohexanediyl unit, preferably a 1,2-cyclohexanediyl unit. The presence of these cyclic structures in the central block is caused by the very specific insertion of ethylene and 1,3-butadiene during their copolymerization. The mechanism for obtaining this microstructure is described, for example, in Macromolecules 2009 (42, 3774-3779). The content of the 1,2-cyclohexanediyl and 1,4-cyclohexanediyl units in the central block varies depending on the respective content of ethylene and 1,3-butadiene in the central block. For the case where the ethylene content in the central block is the highest, the central block typically contains less than 10 mol% of 1,2-cyclohexanediyl units and 1,4-cyclohexanediyl units. For the case where the ethylene content in the central block is the lowest, the central block can contain more than 10 mol% of 1,2-cyclohexanediyl units and 1,4-cyclohexanediyl units, for example, up to 15%. This percentage is relative to the molar number of monomer units constituting the central block. The 1,2-cyclohexanediyl unit corresponds to the following formula.

[0022]

[0023] Since the stiffness of triblock polymers increases with the content of ethylene units in the central block, triblock polymers with a particularly high content of ethylene units in the central block may be desirable for applications requiring high stiffness. Preferably, the ethylene units in the central block account for more than 60 mol% of the units constituting the central block; in this case, the central block contains more than 60 mol% of ethylene units. More preferably, the ethylene units in the central block account for at least 70 mol% of the units constituting the central block; in this case, the central block contains at least 70 mol% of ethylene units.

[0024] According to a particular embodiment of the invention, the ethylene units in the central block account for no more than 90 mol% of the units constituting the central block, in which case the central block contains no more than 90 mol% of ethylene units.

[0025] According to another particular embodiment of the invention, the ethylene unit in the central block accounts for no more than 85 mol% of the units constituting the central block, in which case the central block contains no more than 85 mol% of ethylene units.

[0026] Preferably, the central block has a glass transition temperature between -90°C and -20°C. More preferably, the glass transition temperature of the central block is between -60°C and -20°C, and advantageously between -50°C and -30°C.

[0027] The central block preferably has a number-average molar mass greater than or equal to 3000 g / mol and less than or equal to 80000 g / mol.

[0028] The essential characteristic of the "end" block B is that each of them is polyethylene with a number average molar mass greater than or equal to 2000 g / mol and less than or equal to 10000 g / mol. Another essential characteristic of the end block is that it has a melting point above 90°C, preferably above 90°C and below 140°C. Preferably, B represents linear polyethylene.

[0029] The triblock according to the invention can be prepared by a method comprising: statistical copolymerization of a monomer mixture containing ethylene and 1,3-diene, followed by polymerization of ethylene.

[0030] The catalytic systems used in methods for synthesizing block polymers are advantageously based on metallocene and organomagnesium reagents of formula (I).

[0031] p(Cp 1 Cp 2 Nd(BH4) (1+y) Li y (THF) x (I)

[0032] Cp 1 and Cp 2 Same or different, selected from cyclopentadienyl and fluorenyl groups, whether these groups are substituted or unsubstituted.

[0033] P is the bridge Cp 1 and Cp 2 Two groups represent ZR 1 R 2 The group of the group, Z represents silicon or carbon atom, R 1 and R 2 Whether the terms are the same or different, each represents an alkyl group containing 1 to 20 carbon atoms, preferably a methyl group.

[0034] y is an integer equal to or greater than 0.

[0035] x is an integer or a non-integer that is equal to or greater than 0.

[0036] In equation (I), neodymium atoms are connected to Cp atoms linked together by bridge P. 1 and Cp 2 A ligand molecule composed of two groups. Preferably, the symbol P, represented by the term bridge, corresponds to the formula ZR. 1 R 2 Z represents silicon atoms, R 1 and R 2"Same" or "different" refers to an alkyl group containing 1 to 20 carbon atoms. More preferably, bridge P has the formula SiR. 1 R 2 R 1 and R 2 Same as and as defined above. More preferably, P corresponds to formula SiMe2.

[0037] As alternatives to the substituted cyclopentadienyl and fluorene groups, those substituted with alkyl groups containing 1 to 6 carbon atoms, or aryl groups containing 6 to 12 carbon atoms, or trialkylsilyl groups (such as SiMe3) may be mentioned. The choice of groups also depends on the availability of the corresponding molecules, which are substituted cyclopentadienes and fluorenes, because the corresponding molecules are commercially available or readily synthesized.

[0038] As substituted cyclopentadienyl groups, those substituted at position 2 (or 5) and position 3 (or 4) can be mentioned, especially those substituted at position 2, and more particularly tetramethylcyclopentadienyl. In this application, in the case of cyclopentadienyl, position 2 (or 5) indicates the position of the carbon atom adjacent to the carbon atom connected to bridge P, as shown in the figure below.

[0039]

[0040] As substituted fluorene groups, those substituted at positions 2, 7, 3, or 6 can be mentioned, particularly 2,7-di(tert-butyl)fluorene and 3,6-di(tert-butyl)fluorene. As shown in the diagram below, positions 2, 3, 6, and 7 represent the positions of carbon atoms in the ring, and position 9 corresponds to the carbon atom connected to bridge P.

[0041]

[0042] Preferably, Cp 1 and Cp 2 The same and selected from substituted fluorene groups. Advantageously, in formula (I), Cp 1 and Cp 2 Each represents a substituted fluorenyl group or a fluorenyl group, preferably a fluorenyl group. The fluorenyl group has the formula C. 13 H8. Preferably, the metallocene has the formula (Ia), (Ib), (Ic), (Id), or (Ie), wherein the symbol Flu represents the formula C. 13 The fluorene group of H8.

[0043] [{Me2SiFlu2Nd(μ-BH4)2Li(THF)}2] (Ia)

[0044] [Me2SiFlu2Nd(μ-BH4)2Li(THF)] (Ib)

[0045] [Me2SiFlu2Nd(μ-BH4)(THF)] (Ic)

[0046] [{Me2SiFlu2Nd(μ-BH4)(THF)}2] (Id)

[0047] [Me2SiFlu2Nd(μ-BH4)] (Ie)

[0048] The organomagnesium reagents used as cocatalysts in the catalytic system are organomagnesium compounds of formula (II) or (III).

[0049] R B -(Mg-R A ) m -Mg-R B (II)

[0050] X-Mg-R C -Mg-X (III)

[0051] R A It is a divalent aliphatic hydrocarbon chain, which is interrupted by one or more oxygen atoms or sulfur atoms or one or more arylene groups, or is not interrupted.

[0052] R B It contains a benzene ring substituted with a magnesium atom, wherein one of the carbon atoms of the benzene ring adjacent to the magnesium atom is substituted with a methyl, ethyl, or isopropyl group, or forms a ring with the nearest carbon atom of the benzene ring located meta-position in the magnesium atom, and the other carbon atom of the benzene ring adjacent to the magnesium atom is substituted with a methyl, ethyl, or isopropyl group.

[0053] R C It is a divalent aliphatic hydrocarbon chain, which is interrupted by one or more oxygen atoms or sulfur atoms or one or more arylene groups, or is not interrupted.

[0054] X is a halogen atom.

[0055] m is a number greater than or equal to 1, preferably equal to 1.

[0056] The cocatalysts of formulas (II) and (III) both have the following special characteristics: they include magnesium-carbon bonds involving different magnesium atoms. In formula (II), the two magnesium atoms are each bonded to a group belonging to R. B The first carbon atom shares the first bond and belongs to R A The second carbon atom shares a second bond. The first carbon atom is R. B The constituent atoms of the benzene ring. The second carbon atom is an aliphatic hydrocarbon group R. A The constituent atoms of the aliphatic hydrocarbon chain R A It may contain one or more heteroatoms selected from oxygen and sulfur, or one or more aryl groups within its chain. In the preferred case where m equals 1, each magnesium atom is therefore associated with R.B The first carbon atom shares the first bond and is with R A The second carbon atom shares a second bond. In formula (III), each magnesium atom therefore shares a first bond with a halogen atom and with R. C The carbon atoms share a second bond.

[0057] In equation (II), R B Its characteristic is that it includes a benzene ring substituted with a magnesium atom. R B The two carbon atoms adjacent to magnesium in the benzene ring have the same or different substituents. Alternatively, R... B One of the two carbon atoms adjacent to magnesium in the benzene ring can carry a substituent, while R B The carbon atom adjacent to magnesium in the benzene ring can form a ring. The substituents are methyl, ethyl, or isopropyl. In R... B When one of the two carbon atoms adjacent to magnesium in the benzene ring is substituted with an isopropyl group, R B The second carbon atom of the benzene ring adjacent to magnesium is preferably not substituted with an isopropyl group. Preferably, R... B The carbon atom in the benzene ring adjacent to magnesium is replaced by a methyl or ethyl group. More preferably, R B The carbon atom in the benzene ring adjacent to magnesium is replaced by a methyl group.

[0058] The organomagnesium compound of formula (II) preferably corresponds to formula (IIa-m), wherein m is greater than or equal to 1; R1 and R5 are the same or different, representing methyl or ethyl, preferably methyl; R2, R3 and R4 are the same or different, representing hydrogen atoms or alkyl groups; R A It is a divalent aliphatic hydrocarbon chain, which is interrupted by one or more oxygen atoms or sulfur atoms or one or more arylene groups, or is not interrupted. Preferably, R1 and R5 represent methyl groups. Preferably, R2 and R4 represent hydrogen atoms.

[0059]

[0060] The organomagnesium compounds of formula (IIa-m) are of formula (IIa-1) when m equals 1.

[0061]

[0062] According to preferred variant forms, R1, R3, and R5 are identical in formula (IIa-m), particularly in formula (IIa-1). According to more preferred variant forms, R2 and R4 represent hydrogen and R1, R3, and R5 are identical. In even more preferred variant forms, R2 and R4 represent hydrogen and R1, R3, and R5 represent methyl groups.

[0063] In equations (II) and (IIa-m), especially in equation (IIa-1), RA It is a divalent aliphatic hydrocarbon chain, which may contain one or more heteroatoms selected from oxygen and sulfur, or one or more aryl groups. Preferably, R A It is a branched or linear alkyldiyl, cycloalkyldiyl, or xylenediyl group. More preferably, R A It is an alkyl diol.

[0064] Preferably, R A It contains 3 to 10 carbon atoms, and in particular 3 to 8 carbon atoms.

[0065] Even more preferably, R A It is an alkyldiyl group containing 3 to 10 carbon atoms. Advantageously, R A It is an alkyldiyl group containing 3 to 8 carbon atoms. Very advantageously, R... A It is a linear alkyldiyl group. 1,3-propadiyl, 1,4-butadiyl, 1,5-pentadiyl, 1,6-hexadiyl, 1,7-heptadiyl, and 1,8-octadiyl are particularly suitable as the R group. A .

[0066] According to any embodiment of the invention, in formula (II), particularly in formula (IIa-m), m is preferably equal to 1.

[0067] The organomagnesium compound of formula (II) can be prepared by a method comprising: making X'Mg-R A -MgX' first organomagnesium reagent with formula R B The second organomagnesium reagent reaction of -Mg-X', where X' represents a halogen atom, preferably bromine or chlorine, R B and R A As previously defined, X' is more preferably a bromine atom. The stoichiometry used in the reaction determines the value of m in formulas (II) and (IIa-m). For example, a molar ratio of 0.5 between the amount of the first organomagnesium reagent and the amount of the second organomagnesium reagent favors the formation of an organomagnesium compound of formula (II) with m equal to 1, while a molar ratio greater than 0.5 favors the formation of an organomagnesium compound of formula (II) with m greater than 1.

[0068] To carry out the reaction between the first and second organomagnesium reagents, a solution of the second organomagnesium reagent is typically added to a solution of the first organomagnesium reagent. Both the first and second organomagnesium reagent solutions are usually solutions in ether (such as diethyl ether, dibutyl ether, tetrahydrofuran, methyltetrahydrofuran, or a mixture of two or more of these ethers). Preferably, the concentrations of the first and second organomagnesium reagent solutions are 0.01 mol / L to 3 mol / L and 0.02 mol / L to 5 mol / L, respectively. More preferably, the concentrations of the first and second organomagnesium reagent solutions are 0.1 mol / L to 2 mol / L and 0.2 mol / L to 4 mol / L, respectively.

[0069] The first and second organomagnesium reagents can be prepared in advance from metallic magnesium and suitable precursors via a Grignard reaction. For both the first and second organomagnesium reagents, the respective precursors are of formula X'-R. A -X' and R B -X',R A R B X' is as defined above. Grignard reactions are typically carried out by adding a precursor to metallic magnesium, usually in the form of fragments. Preferably, iodine (I2) is introduced into the reactor, usually in droplet form, prior to the addition of the precursor, thereby activating the Grignard reaction in a known manner.

[0070] Alternatively, the organomagnesium compound according to the invention can be made by using the formula MR A -M organometallic compounds and formula R B It is prepared by the reaction of -Mg-X' with an organomagnesia reagent, where M represents a lithium, sodium, or potassium atom, and X', R B and R A As previously defined. Preferably, M represents a lithium atom, in which case the formula MR A -M organometallic compounds are organolithium reagents.

[0071] The reaction between organolithium and organomagnesium reagents is typically carried out in an ether (e.g., diethyl ether, dibutyl ether, tetrahydrofuran, or methyltetrahydrofuran). The reaction is also typically carried out at temperatures ranging from 0°C to 60°C. Preferably, the contact is carried out at temperatures between 0°C and 23°C. Formula MR A -M organometallic compounds and formula R B Contact with organomagnesium reagents of -Mg-X' is preferably achieved by using organometallic compounds MR A -M solution added to organomagnesium reagent R B The reaction is carried out in a solution of -Mg-X'. Organometallic compounds MR ASolutions of -M are typically solutions in hydrocarbon solvents (preferably n-hexane, cyclohexane, or methylcyclohexane). Organomagnesium reagent R B Solutions of -Mg-X' are typically in ether (preferably diethyl ether or dibutyl ether). Preferably, organometallic compounds MR A -M solution and organomagnesium reagent R B The concentrations of the -Mg-X' solutions were respectively from 0.01 mol / L to 1 mol / L and from 0.02 mol / L to 5 mol / L. More preferably, the organometallic compound MR A -M solution and organomagnesium reagent R B The concentrations of the -Mg-X' solutions were 0.05 mol / L to 0.5 mol / L and 0.2 mol / L to 3 mol / L, respectively.

[0072] As with any synthesis in the presence of organometallic compounds, the described synthesis of organomagnesia reagents was carried out in a stirred reactor under anhydrous conditions and an inert atmosphere. Typically, the solvent and solution were used under anhydrous nitrogen or argon.

[0073] When an organomagnesium compound of formula (II) is formed, it is typically recovered into solution after filtration under an inert anhydrous atmosphere. It can be stored in solution in a sealed container (e.g., a capped bottle) at a temperature between -25°C and 23°C before use.

[0074] Like any organomagnesia compound, the organomagnesia compound of formula (II) can be in the form of a monomer (R B -(Mg-R A ) m -Mg-R B )1, or in the form of polymeric substances (R B -(Mg-R A ) m -Mg-R B ) p (where p is an integer greater than 1), especially dimers (R B -(Mg-R A ) m -Mg-R B )2, where m is as defined above. In addition, whether in monomeric or polymeric form, it may also be a substance in which one or more molecules of a solvent (preferably an ether, such as diethyl ether, tetrahydrofuran or methyltetrahydrofuran) are coordinated.

[0075] In equation (III), R C It is a divalent aliphatic hydrocarbon chain, which may contain one or more heteroatoms selected from oxygen and sulfur, or one or more aryl groups. Preferably, R CIt is a branched or linear alkyldiyl, cycloalkyldiyl, or xylenediyl group. More preferably, R C It is an alkyl diol.

[0076] Preferably, R C It contains 3 to 10 carbon atoms, and in particular 3 to 8 carbon atoms.

[0077] Even more preferably, R C It is an alkyldiyl group containing 3 to 10 carbon atoms. Advantageously, R C It is an alkyldiyl group containing 3 to 8 carbon atoms. Very advantageously, R... C It is a linear alkyldiyl group. 1,3-propadiyl, 1,4-butadiyl, 1,5-pentadiyl, 1,6-hexadiyl, 1,7-heptadiyl, and 1,8-octadiyl are particularly suitable as the R group. C .

[0078] Compounds of formula (III) are well-known Grignard reagents. However, they are not used as co-catalysts in catalytic systems for the preparation of triblock polymers. Grignard reagents of formula (III) are described, for example, in J. March's "Advanced Organic Chemistry" (4th edition, 1992, pp. 622-623) or in Gary S. Silverman and Philip E. Rakita's "Handbook of Grignard Reagents" (1996, pp. 502-503). They can be synthesized by reacting metallic magnesium with formula XR... C Synthesized by contacting -X dihalogen compounds, R C As defined in this invention. For information on their synthesis, see, for example, the compilations of volumes of "Organic Synthesis".

[0079] Like any organomagnesium compound, the organomagnesium compound of formula (III) can be in the form of a monomer (X-Mg-R). C -Mg-X)1, or in the form of polymeric substances (X-Mg-R) C -Mg-X) p (p is an integer greater than 1), especially the dimer (X-Mg-R C -Mg-X)2. In addition, whether in monomeric or polymeric form, it can also be a substance in which one or more molecules of a solvent (preferably an ether, such as diethyl ether, tetrahydrofuran or methyltetrahydrofuran) are coordinated.

[0080] The catalytic system can be routinely prepared using methods similar to those described in patent applications WO 2007054224 or WO 2007054223. For example, organomagnesia reagents and metallocenes are typically reacted in hydrocarbon solvents at temperatures ranging from 20°C to 80°C for a time between 5 and 60 minutes. The catalytic system is typically prepared in aliphatic hydrocarbon solvents (such as methylcyclohexane) or aromatic hydrocarbon solvents (such as toluene).

[0081] The metallocene used to prepare the catalytic system can be in the form of crystalline or amorphous powder, or in single-crystal form. The metallocene can be in monomeric or dimer form, depending on the method of preparation, as described, for example, in patent applications WO 2007 / 054224 or WO 2007 / 054223. The metallocene can be routinely prepared by methods similar to those described in patent applications WO 2007 / 054224 or WO 2007 / 054223, particularly by reacting an alkali metal salt of the ligand with a rare earth metal borohydride (in this case, neodymium) under inert and anhydrous conditions in a suitable solvent (e.g., an ether (such as diethyl ether or tetrahydrofuran), or any other solvent known to those skilled in the art). Following the reaction, the metallocene is separated from the reaction byproducts using techniques known to those skilled in the art, such as filtration or precipitation from a second solvent. Finally, the metallocene is dried and separated in solid form.

[0082] As with any synthesis in the presence of organometallic compounds, the synthesis of metallocenes and catalytic systems is carried out under an inert atmosphere and anhydrous conditions. Typically, the reaction begins with anhydrous solvents and compounds under anhydrous nitrogen or argon atmosphere.

[0083] A catalytic system is typically introduced into a reactor containing a polymerization solvent and monomers. To achieve the desired macroscopic structure of the triblock polymer, those skilled in the art adjust the polymerization conditions, particularly the molar ratio of the organomagnesium reagent to the metal Nd constituting the metallocene. The amounts of the co-catalyst and the metallocene satisfy a ratio of the molar number of Mg in the co-catalyst to the molar number of the rare earth metal in the metallocene preferably from 1 to 200, more preferably from 1 to less than 20. A value range of 1 to less than 20 is particularly advantageous for obtaining polymers with high molar masses. The catalytic system is typically prepared in an aliphatic hydrocarbon solvent (such as methylcyclohexane) or an aromatic hydrocarbon solvent (such as toluene). Typically, after its synthesis, the catalytic system is used as is in the method for synthesizing the polymer according to the invention.

[0084] Those skilled in the art also adjust the polymerization conditions and the concentration of each reagent (components of the catalytic system, monomers) according to the equipment (tools, reactors) used to carry out the polymerization and various chemical reactions. As is known to those skilled in the art, the polymerization and treatment of monomers, catalytic systems, and polymerization solvents are carried out under anhydrous conditions and an inert atmosphere. The polymerization solvent is typically an aliphatic hydrocarbon solvent or an aromatic hydrocarbon solvent.

[0085] Polymerization is preferably carried out continuously or intermittently in solution in an advantageously stirred reactor. The polymerization solvent can be an aromatic hydrocarbon solvent or an aliphatic hydrocarbon solvent. Examples of polymerization solvents that may be mentioned include toluene and methylcyclohexane. Advantageously, polymerization is carried out in solution with a hydrocarbon solvent.

[0086] The preparation of the central block is carried out by copolymerization of a mixture comprising ethylene and 1,3-diene. The polymerization temperature typically ranges from 30°C to 160°C, preferably varying within the range of 30°C to 120°C. During the preparation of the central block, the temperature of the reaction medium is advantageously kept constant during copolymerization, and the total pressure of the reactor is also advantageously kept constant. The preparation of the central block is terminated by cutting off the monomer supply, particularly by reducing the reactor pressure (preferably to about 3 bar).

[0087] The preparation of end blocks via subsequent ethylene polymerization is continued by applying ethylene pressure in the reactor, which is maintained constant until the desired ethylene consumption is reached to achieve the desired number-average molar mass of the end blocks. The applied ethylene polymerization temperature is preferably the same as the temperature at which the central block is prepared. The polymerization temperature used to prepare the end blocks typically varies from 30°C to 160°C, preferably from 30°C to 120°C. The pressure used to prepare the end blocks typically varies from 1 bar to 150 bar, preferably from 1 bar to 10 bar. The synthesis of the end blocks is terminated when the desired number-average molar mass of the end blocks is reached.

[0088] Polymerization can be stopped by cooling the polymerization medium or by adding an alcohol (preferably an alcohol containing 1 to 3 carbon atoms, such as ethanol). Triblock polymers can be recovered using conventional techniques known to those skilled in the art, such as by precipitation, by evaporating the solvent under reduced pressure, or by stripping.

[0089] Compared to statistical copolymers with the same microstructure and macrostructure as the central block of the triblock polymer, the triblock polymer according to the invention exhibits improved rheological properties. The improvement in rheological properties is evident in the significant increase in viscosity at low shear rates (typically less than 10 rad / s) and minimal effect on viscosity at high shear rates (typically greater than 50 rad / s). This improvement in rheological properties allows for greater control over polymer flow during operations that apply stress to the polymer at low shear rates (e.g., hot extrusion). This result is even more surprising because it is achieved without altering the macrostructure or thermal properties (i.e., glass transition temperature) of the polymer. In fact, the triblock polymer maintains a linear chain structure, just like statistical copolymers with the same microstructure as the central block, and it retains the glass transition temperature value of the same statistical copolymer. Preferably, the triblock polymer according to the invention is an elastomer.

[0090] The triblock polymer according to the invention can be used in compositions that are another subject of the invention, the composition further comprising another component. This other component may be a filler (such as carbon black or silica), a plasticizer (such as oil), a crosslinking agent (such as sulfur or peroxide), or an antioxidant. The other component may also be a polymer, particularly an elastomer. The composition may be a rubber composition.

[0091] In summary, the present invention is advantageously carried out according to any one of the following embodiments 1 to 24:

[0092] Implementation Scheme 1: A triblock polymer of formula BAB, wherein symbol A represents a “central” block, which is a statistical copolymer comprising 1,3-diene units and more than 50 mol% ethylene units, and symbols B each represent “end” blocks, which are polyethylenes with a melting point above 90°C and a number-average molar mass greater than or equal to 2000 g / mol and less than or equal to 10000 g / mol, and the content of ethylene units in the central block is expressed as a molar percentage relative to the number of moles of the monomer units constituting the central block.

[0093] Implementation Scheme 2: The triblock polymer according to Implementation Scheme 1, wherein the central block is a statistical copolymer of ethylene and 1,3-diene.

[0094] Implementation Scheme 3: The triblock polymer according to any one of Implementation Schemes 1 and 2, wherein the central block comprises more than 60 mol% ethylene units.

[0095] Implementation Scheme 4: The triblock polymer according to any one of Implementation Schemes 1 to 3, wherein the central block comprises at least 70 mol% ethylene units.

[0096] Implementation Scheme 5: The triblock polymer according to any one of Implementation Schemes 1 to 4, wherein the central block comprises no more than 90 mol% ethylene units.

[0097] Implementation Scheme 6: The triblock polymer according to any one of Implementation Schemes 1 to 5, wherein the central block comprises no more than 85 mol% ethylene units.

[0098] Implementation Scheme 7: The triblock polymer according to any one of Implementation Schemes 1 to 6, wherein the central block has a glass transition temperature between -90°C and -20°C.

[0099] Implementation Scheme 8: The triblock polymer according to any one of Implementation Schemes 1 to 7, wherein the glass transition temperature of the central block is between -60°C and -20°C.

[0100] Implementation Scheme 9: The triblock polymer according to any one of Implementation Schemes 1 to 8, wherein the glass transition temperature of the central block is between -50°C and -30°C.

[0101] Implementation Scheme 10: The triblock polymer according to any one of Implementation Schemes 1 to 9, wherein the central block has a number-average molar mass greater than or equal to 3000 g / mol and less than or equal to 80000 g / mol.

[0102] Implementation Scheme 11: The triblock polymer according to any one of Implementation Schemes 1 to 10, wherein the 1,3-diene is 1,3-butadiene, isoprene, or a mixture of 1,3-dienes, and one of the 1,3-diene mixtures is 1,3-butadiene.

[0103] Implementation Scheme 12: The triblock polymer according to any one of Implementation Schemes 1 to 11, wherein the 1,3-diene is 1,3-butadiene.

[0104] Implementation Scheme 13: The triblock polymer according to any one of Implementation Schemes 1 to 12, wherein the 1,3-diene is 1,3-butadiene or a mixture of 1,3-dienes, one of the 1,3-diene mixtures being 1,3-butadiene, and the central block comprises a 1,2-cyclohexanediyl unit or a 1,4-cyclohexanediyl unit.

[0105] Implementation Scheme 14: The triblock polymer according to any one of Implementation Schemes 1 to 13, wherein the 1,3-diene is 1,3-butadiene or a mixture of 1,3-dienes, one of the 1,3-diene mixtures being 1,3-butadiene, and the central block comprises a 1,2-cyclohexanediol unit.

[0106] Implementation Scheme 15: The triblock polymer according to any one of Implementation Schemes 1 to 14, wherein the 1,2-configured 1,3-diene units and the 3,4-configured 1,3-diene units account for more than 50 moles of the 1,3-diene units.

[0107] Implementation Scheme 16: The triblock polymer according to any one of Implementation Schemes 1 to 15, wherein the central block comprises a 1,3-diene unit in a 1,4 configuration.

[0108] Implementation Scheme 17: The triblock polymer according to any one of Implementation Schemes 1 to 16, wherein the central block comprises a 1,3-diene unit in the trans-1,4 configuration.

[0109] Implementation Scheme 18: The triblock polymer according to Implementation Scheme 17, wherein the trans-1,4 configuration 1,3-diene units account for more than 50 moles of the 1,4 configuration 1,3-diene units.

[0110] Implementation Scheme 19: The triblock polymer according to Implementation Scheme 17 or 18, wherein the trans-1,4 configuration 1,3-diene unit accounts for 100 moles of the 1,4 configuration 1,3-diene unit.

[0111] Implementation Scheme 20: The triblock polymer according to any one of Implementation Schemes 1 to 19, wherein B represents linear polyethylene.

[0112] Implementation Scheme 21: The triblock polymer according to any one of Implementation Schemes 1 to 20, wherein the melting point of the end blocks is above 90°C and below 140°C.

[0113] Implementation Scheme 22: The triblock polymer according to any one of Implementation Schemes 1 to 21, wherein the polymer is an elastomer.

[0114] Implementation Scheme 23: A composition comprising the triblock polymer according to any one of Implementation Schemes 1 to 22 and another component.

[0115] Implementation Scheme 24: A method for synthesizing the triblock polymer defined in any one of Implementation Schemes 1 to 22, said method comprising: statistically copolymerizing a monomer mixture comprising ethylene and 1,3-diene in the presence of a catalytic system, followed by polymerization of ethylene, said catalytic system being based on at least one metallocene of formula (I) and an organomagnesium reagent of formula (II) or (III).

[0116] p(Cp 1 Cp 2 Nd(BH4) (1+y) Li y (THF) x(I)

[0117] R B -(Mg-R A ) m -Mg-R B (II)

[0118] X-Mg-R C -Mg-X (III)

[0119] Cp 1 and Cp 2 Same or different, selected from cyclopentadienyl and fluorenyl groups, whether these groups are substituted or unsubstituted.

[0120] P is the bridge Cp 1 and Cp 2 Two groups represent ZR 1 R 2 The group of the group, Z represents silicon or carbon atom, R 1 and R 2 Whether the terms are the same or different, each represents an alkyl group containing 1 to 20 carbon atoms, preferably a methyl group.

[0121] y is an integer equal to or greater than 0.

[0122] x is an integer equal to or greater than 0, or a non-integer.

[0123] R A It is a divalent aliphatic hydrocarbon chain, which is interrupted by one or more oxygen atoms or sulfur atoms or one or more arylene groups, or is not interrupted.

[0124] R B It contains a benzene ring substituted with a magnesium atom, wherein one of the carbon atoms of the benzene ring adjacent to the magnesium atom is substituted with a methyl, ethyl, or isopropyl group, or forms a ring with the nearest carbon atom of the benzene ring located meta-position in the magnesium atom, and the other carbon atom of the benzene ring adjacent to the magnesium atom is substituted with a methyl, ethyl, or isopropyl group.

[0125] R C It is a divalent aliphatic hydrocarbon chain, which is interrupted by one or more oxygen atoms or sulfur atoms or one or more arylene groups, or is not interrupted.

[0126] X is a halogen atom.

[0127] m is a number greater than or equal to 1, preferably equal to 1. Detailed Implementation

[0128] The above-mentioned and other features of the invention will become clearer by reading the following description of several embodiments of the invention given in a non-limiting manner.

[0129] Example:

[0130] High-Temperature Size Exclusion Chromatography (HT-SEC): HT-SEC analysis was performed using a Viscotek (Malvern Instruments) system equipped with three columns (PLgel Olexis 300mm x 7mm ID from Agilent Technologies) and three detectors (differential refractometer, viscometer, and light scattering). The chromatography was performed at 150°C using 1 mL min… -1 The flow rate was 200 μl of eluting solution in 1,2,4-trichlorobenzene at a concentration of 3 mg / min. -1 The sample solution. The mobile phase consisted of 2,6-di(tert-butyl)-4-methylphenol (400 mg / L). -1 Stable. OmniSEC software was used for data acquisition and analysis. A universal calibration curve was used (based on a polystyrene standard sample using a refractometer and viscometer from the Polymer Standard Service (Mainz) with peak molar mass M). p : 672 to 12,000,000 g mol -1 Calibration was used to calculate the number-average molar mass (Mn) and mass-average molar mass (Mw) of the synthesized ethylene-butadiene copolymer. Dispersibility was also calculated. ( ).

[0131] Nuclear magnetic resonance (NMR): High-resolution images of the copolymer were obtained on a Brüker 400 Avance III spectrometer equipped with a 5 mm BBFO probe and operated at 400 MHz. 1 ¹H NMR spectra. Acquisition was performed at 363 K. A mixture of tetrachloroethylene (TCE) and deuterated benzene (C6D6) (2 / 1 v / v) was used as the solvent. The concentration was 17 g / L. -1 The concentration of the sample was analyzed. Chemical shifts are expressed in ppm relative to the deuterated benzene proton signal set at 7.16 ppm. The sample size was set to 512.

[0132] Differential scanning calorimetry (DSC): In DSC 3 + The analysis was performed on the machine (Mettler Toledo) using a dynamic method comprising nine temperature stages: Stage 1: 20°C to 180°C (10°C min). -1 Phase 2: Isothermal at 180℃ (5 minutes); Phase 3: 180℃ to -80℃ (-10℃ min). -1 Phase 4: Isothermal -80℃ (5 minutes), Phase 5: -80℃ to 180℃ (10℃ min) -1Phase 6: Isothermal at 180℃ (5 minutes); Phase 7: 180℃ to -80℃ (10 minutes). -1 Stage 8: Isothermal -80℃ (5 minutes), Stage 9: -80℃ to 180℃ (10 minutes) -1 The first two rises allow for the elimination of the sample's thermal history. The glass transition temperature and melting point are measured in the ninth stage. The seventh stage is also retained to obtain information about the sample's crystallization.

[0133] Rheological analysis: Analyzed on a MARS 60 rotational rheometer (Thermo Scientific) equipped with a lower plate / Peltier upper oven assembly (with an 8mm plate-to-plate geometry). Powder samples were pressed into discs (1mm to 1.5mm thick) at 150°C for 5 minutes, then punched into 8mm diameter discs. These were then inserted into the rheometer at 150°C.

[0134] Example 1: Preparation of co-catalyst 1,5-bis(magnesium bromide)pentadiyl (DMBP):

[0135] 1.25 g (50 mmol, 10 equivalents) of magnesium was inertized in a 50 mL flask fitted with magnetized olive oil and a 10 mL dropping funnel. 10 mg of diiodine solution was added dropwise to the magnesium. While stirring, 11 mL of MeTHF distilled from sodium / benzophenone was added to the flask, and 9 mL to the dropping funnel. 0.68 mL of 1,5-dibromopentane (5 mmol, 1 equivalent), degassed and dried on an activated molecular sieve, was added to the dropping funnel. The haloalkane solution was added dropwise to the magnesium over 1 hour. The mixture was stirred continuously at 20 °C for 12 hours. The solution was concentrated under vacuum and then diluted with 10 mL of toluene. The concentration of the pentyl group was estimated to be 0.45 mol / L. -1 .

[0136] 1 ¹H NMR (C6D6-400MHz-298K) δ: ppm=2.06(quint, J=7.6Hz, “b”), 1.80(quint, J=7.4Hz, “c”), -0.05(t, J=7.7Hz, “a”); quint is a quintet.

[0137]

[0138] Example 2: Preparation of a reference statistical copolymer of ethylene and 1,3-butadiene

[0139] 200 mL of toluene (Biosolve) purified on an SPS800 MBraun system was placed into a 250 mL inert flask equipped with magnetized olive oil. While stirring, 0.31 mL (0.14 mmol) of 1,5-bis(magnesium bromide)pentanediol (DMBP 0.45 mol / L) prepared according to Example 1 was added to the flask. -1 The solution was then added to the flask. Then 32 mg (50 μmol) of neodymium (Me₂Si(C) was added. 13 H8)2)Nd(-BH4)[(-BH4)Li(THF)]}2.

[0140] Under an inert atmosphere at 70°C, the catalytic solution was transferred to a 250 mL reactor via a sleeve. The argon overpressure in the reactor was reduced to 0.5 bar, and then the reactor was pressurized to 4 bar with an 80 / 20 molar ratio ethylene / butadiene mixture under stirring at 1000 rpm. The pressure in the reactor was kept constant through a vessel containing the ethylene / butadiene mixture. The pressure drop within the vessel was equivalent to approximately 10 g of monomer (yielding the desired Mn of 72000 g mol). -1 Afterward, the feed was stopped, the reactor was degassed, and the temperature was lowered to 20°C. The copolymer solution was precipitated from methanol with stirring in the presence of approximately 20 mg of 2,2'-methylenebis(6-tert-butyl-4-methylphenol) as an antioxidant. The resulting copolymer was then vacuum-dried at 70°C for 4 hours.

[0141] Example 3: Preparation of a triblock polymer according to the present invention, wherein the triblock polymer has a central block of a statistical copolymer of ethylene and 1,3-butadiene and a polyethylene end block:

[0142] 200 mL of toluene (Biosolve) purified on an SPS800 MBraun system was placed into a 250 mL inert flask equipped with magnetized olive oil. While stirring, 0.6 mL (0.25 mmol) of 1,5-bis(magnesium bromide)pentanediol (DMBP 0.45 mol / L) prepared according to Example 1 was added to the flask. -1 The solution was then added to the flask. Then 16 mg (25 μmol of neodymium){(Me₂Si(C)} was added. 13 H8)2)Nd(-BH4)[(-BH4)Li(THF)]}2.

[0143] Preparation of the central block copolymer (Step 1): Under an inert atmosphere at 70°C, the catalytic solution was transferred to a 250 mL reactor via a sleeve. The argon overpressure in the reactor was reduced to 0.5 bar, and then the reactor was pressurized to 4 bar with an 80 / 20 molar ratio ethylene / butadiene mixture under stirring at 1000 rpm. The pressure in the reactor was kept constant through a tank containing the ethylene / butadiene mixture. After the pressure in the tank dropped to the equivalent of approximately 13 g of monomer, the feed was stopped and the reactor was isolated until the pressure in the reactor reached 2.8 bar, yielding 15 g of copolymer, i.e., 60000 g / mol of Mn for the central block copolymer. -1 .

[0144] Preparation of end-blocks (step 2): The reactor was repressurized to 4 bar using a tank containing only ethylene, and then approximately 3 g of monomer was consumed by the pressure drop within the tank, resulting in a required Mn content of 6000 g / mol for each end-block. -1 .

[0145] The reactor was degassed, and the temperature was lowered to 20°C. The polymer solution was precipitated from methanol under stirring in the presence of approximately 20 mg of 2,2'-methylenebis(6-tert-butyl-4-methylphenol) as an antioxidant. The resulting copolymer was then vacuum-dried at 70°C for 4 hours.

[0146] The properties of the polymer are shown in Table 1. In Table 1, the contents of ethylene units, 1,3-butadiene units in the 1,2-configuration (1,2 units), 1,3-butadiene units in the 1,4-configuration (1,4 units), and 1,2-cyclohexanediyl units (cyclic units) are expressed as molar percentages relative to all monomer units of the polymer. Rheological properties are shown in Table 2.

[0147] [Table 1]

[0148]

[0149] [Table 2]

[0150] Example G' at 0.1Hz and 150℃ G' at 10Hz and 150℃ 2 100 100 3 285 115

[0151] A comparison of Examples 2 and 3 shows that the G' value of the triblock polymer increases relative to the reference polymer at low shear rates (typically less than 10 rad / s). In fact, at 0.1 Hz (i.e., 0.6 rad / s), it is almost three times that of the reference polymer. For high shear rates (typically greater than 50 rad / s), the multiplication factor is much smaller, as it is only 1.1 at 10 Hz (i.e., 62 rad / s).

[0152] Using the triblock polymer according to the invention as a substitute for the statistical polymer does indeed result in a significant increase in the polymer viscosity at low shear rates, while the effect on viscosity at high shear rates is relatively small. This increase in viscosity at low shear rates allows for the restriction of polymer flow during conversion at low shear rates without significantly altering its rheological properties at high shear rates. These results reflect an improvement in the rheological properties of the statistical copolymer of ethylene and 1,3-diene without changing the macroscopic structure of the triblock relative to the statistical copolymer or the microstructure of the statistical copolymer portion, thus preserving the inherent properties of the statistical copolymer in the triblock polymer.

Claims

1. A triblock polymer of formula BAB, wherein the symbol A represents a "central" block, which is a statistical copolymer comprising 1,3-diene units and greater than 50 mol% ethylene units, and the symbols B each represent "end" blocks, which are polyethylenes with a melting point above 90°C and a number-average molar mass greater than or equal to 2000 g / mol and less than or equal to 10000 g / mol, wherein the content of ethylene units in the central block is expressed as a molar percentage relative to the number of moles of monomer units constituting the central block, wherein, The central block contains no more than 90 mol% ethylene units.

2. The triblock polymer according to claim 1, wherein, The central block is a statistical copolymer of ethylene and 1,3-diene.

3. The triblock polymer according to claim 1 or 2, wherein, The central block contains more than 60 mol% of ethylene units.

4. The triblock polymer according to claim 1, wherein, The central block contains no more than 85 mol% ethylene units.

5. The triblock polymer according to claim 1, wherein, The central block has a glass transition temperature between -90°C and -20°C.

6. The triblock polymer according to claim 1, wherein, The central block has a number-average molar mass greater than or equal to 3000 g / mol and less than or equal to 80000 g / mol.

7. The triblock polymer according to claim 1, wherein, The 1,3-diene is 1,3-butadiene, isoprene, or a mixture of 1,3-dienes, wherein one of the 1,3-diene mixtures is 1,3-butadiene.

8. The triblock polymer according to claim 1, wherein, The 1,3-diene is 1,3-butadiene or a mixture of 1,3-dienes, wherein one of the 1,3-diene mixtures is 1,3-butadiene, and the central block comprises a 1,2-cyclohexanediyl unit or a 1,4-cyclohexanediyl unit.

9. The triblock polymer according to claim 1, wherein, The polymer is an elastomer.

10. A composition comprising the triblock polymer according to any one of claims 1 to 9 and another component.

11. A method for synthesizing the triblock polymer as defined in any one of claims 1 to 9, the method comprising: In the presence of a catalytic system, a monomer mixture comprising ethylene and 1,3-diene is statistically copolymerized, followed by polymerization of ethylene, wherein the catalytic system is based on at least one metallocene of formula (I) and an organomagnesium reagent of formula (II) or (III). P(Cp 1 Cp 2 )Nd(BH4) (1+y) Liy(THF) x (I) R B -(Mg-R A ) m -Mg-R B (II) X-Mg-R C -Mg-X (III) Cp 1 and Cp 2 Same or different, selected from cyclopentadienyl and fluorenyl groups, whether these groups are substituted or unsubstituted. P is the bridge Cp 1 and Cp 2 Two groups represent ZR 1 R 2 The group of the group, Z represents silicon or carbon atom, R 1 and R 2 "Identical" or "different" respectively indicate alkyl groups containing 1 to 20 carbon atoms. y is an integer equal to or greater than 0. x is an integer equal to or greater than 0, or a non-integer. R A It is a divalent aliphatic hydrocarbon chain, which is interrupted by one or more oxygen atoms or sulfur atoms or one or more arylene groups, or is not interrupted. R B It contains a benzene ring substituted with a magnesium atom, wherein one of the carbon atoms of the benzene ring adjacent to the magnesium atom is substituted with a methyl, ethyl, or isopropyl group, or forms a ring with the nearest carbon atom of the benzene ring located meta-position in the magnesium atom, and the other carbon atom of the benzene ring adjacent to the magnesium atom is substituted with a methyl, ethyl, or isopropyl group. R C It is a divalent aliphatic hydrocarbon chain, which is interrupted by one or more oxygen atoms or sulfur atoms or one or more arylene groups, or is not interrupted. X is a halogen atom. m is a number greater than or equal to 1.

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