阅读说明：本技术 乙烯和1,3-二烯的共聚物 (Copolymers of ethylene and 1, 3-dienes ) 是由 V·拉法基耶尔 E·莫雷索 于 2019-03-18 设计创作，主要内容包括：本发明涉及乙烯和式CH<Sub>2</Sub>＝CR-CH＝CH<Sub>2</Sub>的1,3-二烯的共聚物,其中,乙烯单元占乙烯单元和1,3-二烯单元的50摩尔％和95摩尔％之间,1,2构型和3,4构型的1,3-二烯单元占1,3-二烯单元的超过50摩尔％,符号R表示具有3至20个碳原子的烃链。这种共聚物在结晶度和刚度之间具有改进的折中,并且能够拓宽富含乙烯的二烯共聚物在橡胶组合物中的应用领域。(The invention relates to ethylene and to the formula CH 2 ＝CR‑CH＝CH 2 Wherein the ethylene units represent between 50 and 95 mol% of the ethylene units and of the 1, 3-diene units, the 1, 3-diene units of 1,2 configuration and of 3,4 configuration represent more than 50 mol% of the 1, 3-diene units, and the symbol R represents a hydrocarbon chain having from 3 to 20 carbon atoms. Such copolymers have an improved compromise between crystallinity and stiffness and allow a broadening of the field of application of ethylene-rich diene copolymers in rubber compositions.)

1. A copolymer of ethylene and a 1, 3-diene of formula (I), said copolymer comprising ethylene units and 1, 3-diene units, said ethylene units constituting between 50 and 95 mol% of the ethylene units and of the 1, 3-diene units, the 1, 2-configuration and 3, 4-configuration 1, 3-diene units constituting more than 50 mol% of the 1, 3-diene units,

CH₂＝CR-CH＝CH₂(I)

the symbol R represents a hydrocarbon chain having 3 to 20 carbon atoms.

2. The copolymer of claim 1, wherein the ethylene units comprise at least 60 mole percent of the ethylene units and 1, 3-diene units.

3. The copolymer of claim 1 or 2, wherein the ethylene units comprise 60 to 90 mol% of the ethylene units and 1, 3-diene units.

4. The copolymer of any of claims 1 to 3, wherein the ethylene units comprise at least 70 mol% of the ethylene units and 1, 3-diene units.

5. The copolymer of any of claims 1 to 4, wherein the ethylene units comprise from 70 to 90 mol% of the ethylene units and 1, 3-diene units.

6. The copolymer according to any one of claims 1 to 5, wherein the symbol R represents a hydrocarbon chain having from 6 to 16 carbon atoms.

7. The copolymer according to any one of claims 1 to 6, wherein the symbol R represents a non-cyclic chain.

8. The copolymer according to any one of claims 1 to 7, wherein the symbol R represents a linear or branched chain.

9. The copolymer according to any one of claims 1 to 8, wherein the symbol R represents a saturated chain or an unsaturated chain.

10. The copolymer of any one of claims 1 to 9 having a glass transition temperature of less than-35 ℃.

11. The copolymer of any one of claims 1 to 10, having a glass transition temperature between-90 ℃ and-35 ℃.

12. The copolymer of any one of claims 1 to 11, which is a random copolymer.

13. The copolymer of any one of claims 1 to 12, which is an elastomer.

14. Process for preparing a copolymer as defined in any one of claims 1 to 13, which comprises polymerizing ethylene and a 1, 3-diene in the presence of a catalytic system based on at least a metallocene of formula (II) and an organomagnesium compound of formula (III)

P(Cp¹Cp²)Nd(BH₄)_(1+y)-L_y-N_x(II)

MgR¹R²(III)

Cp¹And Cp²Same or different, selected from substituted fluorenyl and formula C₁₃H₈(ii) an unsubstituted fluorenyl group of (a),

p is a bridged Cp¹And Cp²Two radicals and representing ZR³R⁴Group of radicals, Z representing a silicon or carbon atom, R³And R⁴Identical or different, each represents an alkyl group containing from 1 to 20 carbon atoms, preferably a methyl group,

y is an integer equal to or greater than 0,

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

l represents an alkali metal selected from lithium, sodium and potassium,

n represents an ether molecule, preferably diethyl ether or tetrahydrofuran,

R¹and R²The same or different, represent carbon radicals.

15. The process of claim 14 wherein the metallocene is of formula (IIa), (IIb), (IIc), (IId) or (IIe)

[{Me₂SiFlu₂Nd(μ-BH₄)₂Li(THF)}₂](IIa)

[Me₂SiFlu₂Nd(μ-BH₄)₂Li(THF)](IIb)

[Me₂SiFlu₂Nd(μ-BH₄)(THF)](IIc)

[{Me₂SiFlu₂Nd(μ-BH₄)(THF)}₂](IId)

[Me₂SiFlu₂Nd(μ-BH₄)](IIe)

Symbol Flu represents formula C₁₃H₈A fluorenyl group of (1).

16. The method of any one of claims 14 and 15, wherein R¹And R²Containing 2 to 10 carbon atoms.

17. The method of any one of claims 14 to 16, wherein R¹And R²Each represents an alkyl group.

18. The process according to any one of claims 14 to 17, wherein the organomagnesium compound is a dialkylmagnesium compound, preferably butylethylmagnesium or butyloctylmagnesium, more preferably butyloctylmagnesium.

19. Rubber composition based on at least a copolymer and a crosslinking system as defined in claim 13.

20. The rubber composition of claim 19, comprising a reinforcing filler.

21. A tire comprising the rubber composition as defined in any one of claims 19 and 20.

Technical Field

Background

The diene elastomers most widely used in tire manufacture are polybutadiene, polyisoprene (especially natural rubber) and copolymers of 1, 3-butadiene and styrene. These elastomers have in common that the molar proportion of diene units in the elastomer is high (generally much greater than 50%), which makes them susceptible to oxidation, in particular under the action of ozone.

In contrast, the applicant company has described elastomers having relatively few diene units, in particular in order to reduce their susceptibility to oxidation phenomena. These elastomers are described, for example, in document WO 2007054223. These elastomers are copolymers of 1, 3-butadiene and ethylene containing more than 50 mole% of ethylene units. These elastomers are referred to as ethylene-rich diene elastomers.

Ethylene-rich 1, 3-butadiene and ethylene copolymers are crystalline, with crystallinity increasing with ethylene content. When the copolymer is used in a rubber composition, the presence of crystalline portions in the copolymer may cause problems. Since the melting of the crystalline portion of the copolymer leads to a reduction in the rigidity thereof, the rigidity of a rubber composition for tires comprising such a copolymer is also reduced when the temperature reaches or exceeds the melting point of the crystalline portion (as may occur during repeated braking and acceleration phases of the tire). Thus, this dependence of stiffness on temperature variation can lead to uncontrolled fluctuations in tire performance quality. Advantageously, diene polymers rich in ethylene units can be obtained, which reduce (indeed even eliminate) the crystallinity of the polymer.

In document WO2007054224, the applicant company has described ethylene-rich diene copolymers having a reduced crystallinity. These copolymers are copolymers of 1, 3-butadiene and ethylene that additionally contain a saturated six-membered cyclic hydrocarbon motif. However, these copolymers incorporated into the rubber composition may impart excessively high rigidity to the rubber composition. The high stiffness of the rubber composition is due to the equally high stiffness of the elastomer. The high stiffness of the rubber composition may cause problems as it may in itself render the rubber composition unsuitable for certain applications.

In order to produce these ethylene-and 1, 3-butadiene copolymers rich in ethylene and comprising a saturated six-membered cyclic hydrocarbon motif, the applicant company developed a catalytic system based on metallocenes of the formula:

P(Cp¹)(Cp²)Nd(BH₄)_(1+y)-L_y-N_x

Cp¹and Cp²Same or different, selected from substituted fluorenyl and formula C₁₃H₈Unsubstituted fluorenyl radical of (A), P is a bridged Cp¹And Cp²Two radicals and representing ZR³R⁴Group of radicals, Z representing a silicon or carbon atom, R³And R⁴Identical or different, each represents an alkyl group comprising from 1 to 20 carbon atoms, preferably a methyl group, y is an integer equal to or greater than 0, x is an integer equal to or greater than 0 or a non-integer, L represents an alkali metal selected from lithium, sodium and potassium, N represents an ether molecule, preferably diethyl ether or tetrahydrofuran.

For the purpose of synthesizing ethylene-rich diene elastomers, the applicant company has found a new polymer capable of solving the above-mentioned problems.

Disclosure of Invention

A first subject of the invention is therefore a copolymer (preferably an elastomer) of ethylene and a 1, 3-diene of formula (I), said copolymer comprising ethylene units and 1, 3-diene units, the ethylene units constituting between 50% and 95% by mole of the ethylene units and of the 1, 3-diene units, the 1, 2-configuration and 3, 4-configuration 1, 3-diene units constituting more than 50% by mole of the 1, 3-diene units.

CH₂＝CR-CH＝CH₂(I)

The symbol R represents a hydrocarbon chain having 3 to 20 carbon atoms.

Another subject-matter of the invention is a process for preparing the copolymers according to the invention.

The invention also relates to a rubber composition based at least on an elastomer and a crosslinking system according to the invention and to a tire comprising a rubber composition according to the invention.

Detailed Description

I. Detailed description of the invention

In the present description, any numerical interval denoted by the expression "between a and b" means a numerical range greater than "a" and less than "b" (i.e. excluding the limits a and b), while any numerical interval denoted by the expression "from a to b" means a numerical range extending from "a" up to "b" (i.e. including the strict limits a and b).

The expression "based on" used to define the components of the catalytic system or composition is understood to mean mixtures of these components or the reaction products of some or all of these components with one another.

Unless otherwise indicated, the content of units obtained by inserting monomers into the copolymer is expressed in mole percentage with respect to all monomer units of the copolymer.

The compounds mentioned in the description may be of fossil or biological origin. In the case of biological origin, it may be partially or completely derived from biomass or obtained by renewable starting materials derived from biomass. In particular to monomers.

Since the 1, 3-diene of formula (I) as defined above and used for the requirements of the present invention is a substituted 1, 3-diene, the 1, 3-diene can give rise to a unit of 1,2 configuration represented by formula (1), a unit of 3,4 configuration represented by formula (2) and a unit of 1,4 configuration (the trans form of which is represented by the following formula (3)).

As is well known, the ethylene unit is- (CH)₂-CH₂) -units of motifs.

The copolymer according to the invention is a copolymer of ethylene and a 1, 3-diene, which means that the monomer units of the copolymer are units resulting from the polymerization of ethylene and a 1, 3-diene. Thus, the copolymer comprises ethylene units and 1, 3-diene units. According to any one of the embodiments of the invention, the 1, 3-diene required for the purposes of the invention is only one compound (i.e. only one 1, 3-diene of formula (I)) or is a mixture of 1, 3-dienes of formula (I) (the 1, 3-dienes of the mixture differ from one another by the group represented by the symbol R).

The copolymer of ethylene and 1, 3-diene according to the invention is essentially characterized in that it comprises between 50 and 95 mol% of ethylene units. In other words, ethylene units constitute between 50 and 95 mol% of ethylene units and 1, 3-diene units. Another essential feature is that it comprises more than 50 mol% of 1, 3-diene units (1,2 configuration and 1, 3-diene units of 3,4 configuration). In other words, 1, 3-diene units (whether it is in 1,2 configuration or 3,4 configuration) constitute more than 50 mole% of the 1, 3-diene units. The balance of the 1, 3-diene units of 100 mol% in the copolymer is formed wholly or partly by 1, 3-diene units of 1,4 configuration. According to any one of the embodiments of the present invention, preferably, more than half of the 1,4 configuration 1, 3-diene units are in the trans-1, 4 configuration, more preferably, all 1,4 configuration 1, 3-diene units are in the trans-1, 4 configuration.

In the 1, 3-dienes of formula (I) used as required for the present invention, the hydrocarbon chain represented by the symbol R can be linear or branched, in which case the symbol R represents linear or branched. Preferably, the hydrocarbon chain is acyclic, in which case the symbol R represents an acyclic chain. In formula (I), the hydrocarbon chain represented by the symbol R may be saturated or unsaturated, in which case the symbol R represents a saturated chain or an unsaturated chain. Preferably, the symbol R represents a hydrocarbon chain having 6 to 16 carbon atoms.

According to a preferred embodiment of the invention, in the copolymer according to the invention, the ethylene units represent at least 60 mol% of the ethylene units and of the 1, 3-diene units. More preferably, the ethylene units constitute from 60 to 90 mol% of the ethylene units and 1, 3-diene units.

According to a more preferred embodiment of the invention, in the copolymer according to the invention, the ethylene units represent at least 70 mol% of the ethylene units and of the 1, 3-diene units. More preferably, the ethylene units constitute from 70 mol% to 90 mol% of the ethylene units and 1, 3-diene units.

Preferably, the glass transition temperature of the copolymer according to the invention is less than-35 ℃, in particular between-90 ℃ and-35 ℃.

More preferably, the copolymer according to the invention is an elastomer.

The copolymers according to the invention can be prepared by a process comprising copolymerizing ethylene and a 1, 3-diene in the presence of a catalytic system based on at least a metallocene of formula (II) and an organomagnesium compound of formula (III)

P(Cp¹Cp²)Nd(BH₄)_(1+y)-L_y-N_x(II)

MgR¹R²(III)

Cp¹And Cp²Same or different, selected from substituted fluorenyl and formula C₁₃H₈(ii) an unsubstituted fluorenyl group of (a),

p is a bridged Cp¹And Cp²Two radicals and representing ZR³R⁴Group of radicals, Z representing a silicon or carbon atom, R³And R⁴Identical or different, each represents an alkyl group containing from 1 to 20 carbon atoms, preferably a methyl group,

y is an integer equal to or greater than 0,

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

l represents an alkali metal selected from lithium, sodium and potassium,

n represents an ether molecule, preferably diethyl ether or tetrahydrofuran,

R¹and R²The same or different, represent carbon radicals.

As the substituted fluorenyl group, mention may be made of a fluorenyl group substituted with an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms. The choice of group also depends on the availability of the corresponding molecule (substituted fluorenyl) since substituted fluorenyl groups are commercially available or readily synthesized.

As substituted fluorenyl groups, there may be mentioned more particularly 2, 7-di (tert-butyl) fluorenyl and 3, 6-di (tert-butyl) fluorenyl. 2. The positions 3,6 and 7 represent the positions of the carbon atoms of the rings shown in the following figures, respectively, and the position 9 corresponds to the carbon atom attached to the bridge P.

The catalytic system can be prepared conventionally by a process similar to that described in patent application WO 2007054224. For example, the organomagnesium compound and the metallocene may generally be reacted in a hydrocarbon solvent for a period of time (between 5 minutes and 60 minutes) at a temperature in the range of 20 ℃ to 80 ℃. The catalytic system is generally prepared in an aliphatic hydrocarbon solvent (e.g., methylcycloethane) or an aromatic hydrocarbon solvent (e.g., toluene). Generally, after synthesis, the catalytic system is used in this form in the process for synthesizing the copolymers according to the invention.

The metallocene used for preparing the catalytic system may be in the form of a crystalline or amorphous powder, or in the form of a single crystal. The metallocene can be provided in monomeric or dimeric form, these forms depending on the process for preparing the metallocene, as described, for example, in patent application WO 2007054224. Metallocenes may be conveniently prepared by methods analogous to those described in patent application WO2007054224, in particular by reaction of an alkali metal salt of a ligand with a rare earth metal borohydride in a suitable solvent, such as an ether (e.g. diethyl ether or tetrahydrofuran) or any other solvent known to the skilled person, under inert and anhydrous conditions. After the reaction, the metallocene is separated from the reaction by-products by techniques known to those skilled in the art (e.g., filtration or precipitation in a second solvent). Finally, the metallocene is dried and isolated in solid form.

Such as any synthesis carried out in the presence of organometallic compounds, the synthesis of metallocenes and the synthesis of catalytic systems, are carried out under anhydrous conditions in an inert atmosphere. Generally, the reaction is carried out in anhydrous nitrogen or argon starting from an anhydrous solvent and the compound.

Preferably, the metallocene is of formula (IIa), (IIb), (IIc), (IId) or (IIe), wherein the symbol Flu represents formula C₁₃H₈A fluorenyl group of (1).

[{Me₂SiFlu₂Nd(μ-BH₄)₂Li(THF)}₂](IIa)

[Me₂SiFlu₂Nd(μ-BH₄)₂Li(THF)](IIb)

[Me₂SiFlu₂Nd(μ-BH₄)(THF)](IIc)

[{Me₂SiFlu₂Nd(μ-BH₄)(THF)}₂](IId)

[Me₂SiFlu₂Nd(μ-BH₄)](IIe)

The organomagnesium compound required for the present invention is of the formula MgR¹R²Wherein R is¹And R²The same or different, represent carbon radicals. Carbon-based is understood to mean a group comprising one or more carbon atoms. Preferably, R¹And R²Containing 2 to 10 carbon atoms. More preferably, R₁And R₂Each represents an alkyl group. The organomagnesium compound is advantageously a dialkylmagnesium compound, still better still butylethylmagnesium or butyloctylmagnesium, even still better still butyloctylmagnesium.

According to any one of the embodiments of the present invention, the molar ratio of the organomagnesium compound to the metal Nd constituting the metallocene is preferably in the range of 1 to 100, more preferably greater than or equal to 1 and less than 10. A value range of from 1 to less than 10 is particularly advantageous for obtaining copolymers of high molar mass.

The polymerization conditions and the concentrations of the various reactants (components of the catalytic system, monomers) can also be adjusted by the person skilled in the art according to the equipment (plant, reactor) used for carrying out the polymerization and the various chemical reactions. As known to those skilled in the art, the copolymerization and the operation of the monomers, the catalytic system and the polymerization solvent are carried out under anhydrous conditions in an inert atmosphere. The polymerization solvent is usually an aliphatic hydrocarbon solvent or an aromatic hydrocarbon solvent.

The polymerization is preferably carried out continuously or batchwise in solution. The polymerization solvent may be an aromatic hydrocarbon solvent or an aliphatic hydrocarbon solvent. As examples of the polymerization solvent, toluene and methylcyclohexane may be mentioned. The monomer may be introduced into a reactor containing the polymerization solvent and the catalytic system, or conversely, the catalytic system may be introduced into a reactor containing the polymerization solvent and the monomer. The copolymerization is generally carried out under anhydrous conditions in the absence of oxygen in the presence of an optional inert gas. The polymerization temperature generally varies within the range of from 30 ℃ to 150 ℃, preferably from 30 ℃ to 120 ℃. Preferably, the copolymerization is carried out at constant ethylene pressure.

The polymerization can be terminated by cooling the polymerization medium. The polymer may be recovered according to conventional techniques known to those skilled in the art, such as, for example, precipitation, evaporation of the solvent under reduced pressure or steam stripping.

According to any one of the embodiments of the invention, the incorporation of the 1, 3-diene and ethylene into the growing polymer chain is preferably random. The copolymers according to the invention are advantageously random copolymers.

The copolymer according to the invention, in particular when it is an elastomer, can be used in rubber compositions.

The rubber composition (another subject of the invention) is characterized in that it comprises an elastomer according to the invention and a crosslinking system.

The crosslinking system may be based on sulfur, sulfur donors, peroxides, bismaleimides or mixtures thereof. The crosslinking system is preferably a vulcanization system, i.e. a system based on sulfur (or a sulfur donor) and a primary vulcanization accelerator. In addition to the basic vulcanization system are optional various known secondary vulcanization accelerators, vulcanization activators such as zinc oxide, stearic acid or equivalent compounds or guanidine derivatives (especially diphenylguanidine) or known vulcanization retarders.

According to a preferred embodiment of the invention, the rubber composition comprises a reinforcing filler. The rubber composition may comprise any type of "reinforcing" filler known for its ability to reinforce rubber compositions usable for the manufacture of tires, such as organic fillers (for example carbon black), reinforcing inorganic fillers (for example silica combined in a known manner with a coupling agent) or mixtures of these two types of filler. Such reinforcing fillers generally consist of nanoparticles, the (weight) average size of which is less than one micron, generally less than 500nm, most generally between 20nm and 200nm, particularly and more preferably between 20nm and 150 nm. The content of the reinforcing filler can be adjusted by those skilled in the art according to the use of the rubber composition.

The rubber composition may additionally include other additives known for use in tire rubber compositions, such as plasticizers, antiozonants, or antioxidants.

The rubber compositions according to the invention are generally manufactured in a suitable mixer using two successive preparation stages known to those skilled in the art: a first stage of thermomechanical working or kneading at high temperature ("non-productive" stage), with a maximum temperature of between 130 ℃ and 200 ℃, followed by a second stage of mechanical working ("productive" stage), usually lower than 110 ℃ (for example between 40 ℃ and 100 ℃), by the addition of a crosslinking system during the finishing stage.

The rubber compositions according to the invention can be in the raw state (before crosslinking or vulcanization) or in the cured state (after crosslinking or vulcanization) and can be used in semi-finished products for tires.

The tyre (another subject of the invention) comprises a rubber composition according to the invention as defined in any one of the embodiments of the invention.

The above mentioned and other features of the invention will be better understood by reading the following description of several embodiments of the invention, given by way of illustration and not limitation.

Examples of the invention

1)Synthesis of Polymer:

in the synthesis of the copolymers according to the invention, the 1, 3-diene (myrcene) used is a 1, 3-diene of formula (I) in which R is of formula CH₂-CH₂-CH＝CMe₂A hydrocarbon group having 6 carbon atoms.

All reactants are commercially available except for the metallocene [ { Me [ ]₂SiFlu₂Nd(μ-BH₄)₂Li(THF)}]And [ Me ]₂SiCpFluNd(μ-BH₄)₂Li(THF)](prepared according to the procedures described in patent applications WO2007054224 and WO 2007054223).

Butyl octyl magnesium BOMAG (20% heptane, C ═ 0.88mol^-1) From Chemtura and stored in Schlenk tubes under an inert atmosphere. Ethylene (grade N35) was obtained from Air Liquide and was used without purification. Myrcene (purity ≧ 95%) was obtained from Sigma-Aldrich.

1.1-control synthesis: example 1

The polymer was synthesized according to the following procedure:

cocatalyst, Butyl Octyl Magnesium (BOMAG) and metallocene [ Me ]₂SiCpFluNd(μ-BH₄)₂Li(THF)]Into a 500mL glass reactor containing 300mL of toluene. The alkylation time was 10 minutes and the reaction temperature was 20 ℃. Table 2 shows the respective amounts of the components of the catalytic system. Subsequently, the monomers were added according to the various ratios shown in table 2, ethylene (Eth) and 1, 3-butadiene (Bde) being in the form of a gaseous mixture. The polymerization was carried out at 80 ℃ under a constant ethylene pressure of 4 bar.

The polymerization was terminated by cooling, degassing of the reactor and addition of 10mL of ethanol. An antioxidant is added to the polymer solution. The copolymer was recovered by drying in an oven under vacuum to constant weight. The weighed weight enables the determination of the average catalytic activity of the catalytic system (expressed in kilograms of polymer synthesized per mole of neodymium metal per hour (kg/mol.h)).

1.2-not according to the examples of the invention: example 2

The polymer was synthesized according to the following procedure:

cocatalyst, Butyl Octyl Magnesium (BOMAG) and metallocene [ Me ]₂Si(Flu)₂Nd(μ-BH₄)₂Li(THF)]Into a 500mL glass reactor containing 300mL methylcyclohexane. The alkylation time was 10 minutes and the reaction temperature was 20 ℃. Table 2 shows the respective amounts of the components of the catalytic system. Subsequently, the monomers were added according to the various ratios shown in table 2, ethylene (Eth) and 1, 3-butadiene (Bde) being in the form of a gaseous mixture. The polymerization was carried out at 80 ℃ under a constant ethylene pressure of 4 bar.

The polymerization was terminated by cooling, degassing of the reactor and addition of 10mL of ethanol. An antioxidant is added to the polymer solution. The copolymer was recovered by drying in an oven under vacuum to constant weight. The weighed weight enables the determination of the average catalytic activity of the catalytic system (expressed in kilograms of polymer synthesized per mole of neodymium metal per hour (kg/mol.h)).

1.3-according to an embodiment of the invention: examples 3 to 5

The polymer was synthesized according to the following procedure:

cocatalyst, Butyl Octyl Magnesium (BOMAG) and metallocene [ Me ]₂Si(Flu)₂Nd(μ-BH₄)₂Li(THF)]Into a 500mL glass reactor containing 300mL methylcyclohexane. The alkylation time was 10 minutes and the reaction temperature was 20 ℃. Table 2 shows the respective amounts of the components of the catalytic system. Subsequently, myrcene was added to the reactor prior to the injection of gaseous ethylene. The polymerization was carried out at 80 ℃ under a constant ethylene pressure of 4 bar.

The polymerization was terminated by cooling, degassing of the reactor and addition of 10mL of ethanol. An antioxidant is added to the polymer solution. The copolymer was recovered by drying in an oven under vacuum to constant weight. The weighed weight enables the determination of the average catalytic activity of the catalytic system (expressed in kilograms of polymer synthesized per mole of neodymium metal per hour (kg/mol.h)).

The characteristics of the polymers are shown in tables 3 and 4.

2) Determination of the microstructure of the polymer:

spectral characterization and microstructure measurements of copolymers of ethylene and 1, 3-diene (myrcene) were performed by Nuclear Magnetic Resonance (NMR) spectroscopy.

-a spectrometer: for these measurements, a Bruker Avance III HD 400MHz spectrometer equipped with a Bruker cryo-BBFO z grade 5mm probe was used.

-experiment: using RF pulse recording with a tilt angle of 30 DEG¹H experiment, repetition number 128 times, cycle delay 5 seconds. Record HSQC (heteronuclear single quantum coherence) and HMBC (heteronuclear multiple bond correlation)¹H-¹³C NMR related experiments, the number of repetitions is 128, and the number of increments is 128. The experiment was carried out at 25 ℃.

-preparation of the sample: 25mg of the sample was dissolved in 1mLDeuterated chloroform (CDCl)₃) In (1).

Calibration of the sample: relative to solvent (CHCl)₃) In that_1H7.2ppm and_13Cprotonated impurities calibration at 77ppm¹H and¹³axis of C chemical shift.

-spectral assignment: the signals of the inserted form of 1, 3-diene A, B and C (scheme 1) were observed on the different spectra recorded. According to S.Georges et al (S.Georges, M.Bria, P.Zinck and M.Visseaux, Polymer, 55 (2014), 3869-3878), form C is characterized by a-CH-group in position 8 ″¹H and¹³the chemical shift of C is the same as for the-CH ═ group at position 3.

Table 1 shows the chemical shifts of the signature signals for motifs A, B and C. Motifs A, B and C correspond to the units of the 3,4 configuration, the units of the 1,2 configuration and the units of the trans-1, 4 configuration, respectively.

Table 1: process for preparing ethylene/myrcene copolymers¹H and¹³c signal identification

Scheme 1

Use of Topspin software for 1D¹The integral of the H NMR spectrum was quantified.

The integrated signals that quantify the different motifs were:

v. ethylene: signal at 1.2ppm corresponding to 4 protons

V. total myrcene: signal corresponding to position 1 of 6 protons (1.59ppm)

Form a: signal at position 7 (4.67ppm) corresponding to 2 protons

Form B: signal corresponding to 1 proton 8' (5.54ppm)

The quantification of the microstructure was performed in mole percent (mol%) as follows: motif mol% ═ motif¹Integral H100/sigma (per motif)¹H integral).

3) Determination of the stiffness of the polymers (as-processed):

measurements were performed on an Anton Paar model MCR301 rheometer in shear mode using cylindrical test specimens of controlled geometry (thickness between 1.5mm and 3mm, diameter between 22mm and 28 mm). The samples were subjected to sinusoidal shear stress at a fixed temperature (corresponding to the endpoint of elastomer through glass transition at 10Hz under a temperature sweep) at frequencies ranging from 0.01Hz to 100 Hz. The stiffness value selected as the stiffness of the sample rubber platform was the value of the shear modulus G' at the frequency at which the loss modulus G "reached its minimum value, according to the method described in Evaluation of differential methods for the determination of the plant model and the entry molecular weight (Polymer, 47 (2006), 4461-4479) by C.Liu, J.He, E.van Ruymbece, R.Keuning and C.Baily.

4) Determination of the glass transition temperature of the Polymer:

the glass transition temperature was measured by a differential calorimeter (differential scanning calorimeter) according to the standard ASTM D3418 (1999).

5) Determination of the crystallinity of the polymers:

the temperature, the enthalpy of fusion and the crystallinity of the polymers used are determined by Differential Scanning Calorimetry (DSC) using the standard ISO 11357-3: 2011. The reference enthalpy of polyethylene is 277.1J/g (according to Polymer Handbook, 4 th edition, J.Brandrup, E.H.Immergut and E.A.Grulke, 1999).

6) As a result:

in example 1 (control), the metallocene [ Me ] is enriched in ethylene₂SiCpFluNd(μ-BH₄)₂Li(THF)]The diene copolymer synthesized by polymerization of ethylene and 1, 3-butadiene in the presence of (a) has a high crystallinity (31%), which makes it unsuitable for certain applications.

In example 2 (not according to the invention), in the metallocene [ Me ]₂Si(Flu)₂Nd(μ-BH₄)₂Li(THF)]Has a cyclic motif. Although it includesEthylene content comparable to the control, but it was amorphous. However, it has a relatively high stiffness, which makes it unsuitable for certain applications.

In examples 3 to 5 (according to the invention), the ethylene-rich diene copolymer was a copolymer of ethylene and myrcene. In example 3, the copolymer had an ethylene content comparable to the copolymers of examples 1 and 2, but did not exhibit its disadvantages. This is because it has the advantage of being non-crystalline and having a stiffness significantly lower than the copolymer of example 2.

In example 4, the copolymer contained more ethylene (85%) than the control copolymer of example 1 (74%) and had a lower crystallinity (17%) than the control copolymer (31%).

In example 5, the copolymer had a higher myrcene content than the copolymers of examples 3 and 4. It is amorphous and also shows a lower stiffness. Examples 3 to 5 show that variation of the myrcene content in the copolymer compared to a copolymer of ethylene and 1, 3-butadiene enables an improvement of the crystallinity/stiffness compromise of the ethylene-rich diene polymer.

In summary, the formula CH is used₂＝CR-CH＝CH₂(R represents a hydrocarbon chain having 3 to 20 carbon atoms) of a 1, 3-diene (for example, myrcene) in place of 1, 3-butadiene enables the synthesis of an ethylene-rich diene polymer having an improved compromise between crystallinity and rigidity, and enables the widening of the field of application of the ethylene-rich diene copolymer in rubber compositions.