WO2019115470A1

WO2019115470A1 - Method for synthesising a functional or non-functional polymer having a specific structure

Info

Publication number: WO2019115470A1
Application number: PCT/EP2018/084214
Authority: WO
Inventors: Lise MAISONNEUVE; Karima HABHAB; Charlotte Dire
Original assignee: Compagnie Generale Des Etablissements Michelin
Priority date: 2017-12-11
Filing date: 2018-12-10
Publication date: 2019-06-20

Abstract

The invention concerns a method for preparing a modified polymer comprising: - a step of anionic polymerisation of at least one diene monomer in the presence of a difunctional polymerisation initiator, in order to obtain a difunctional living prepolymer comprising a reactive site at each of the two ends of same, then - a step of reacting said difunctional living prepolymer comprising a reactive site at each of the two ends of same by polycondensation by means of a difunctional coupling agent of the following formula (I), in which Y, Z separately refer to a function that is reactive with respect to the living prepolymer, R1 and R2 separately refer to a hydrocarbon group which can be linear, branched or cyclic, saturated or unsaturated, and preferably saturated, and optionally capable of containing one or more heteroatoms, R1 and R2 being devoid of sites that are reactive with respect to the living prepolymer, the molar ratio r = n(difunctional living prepolymer)/n(coupling agent) varying from 0.85 to 1.25.

Description

Process for synthesizing a functional or non-functional polymer with a particular structure

The present invention relates to a method for synthesizing a modified polymer comprising an anionic polymerization step in the presence of a difunctional initiator followed by a polycondensation step with a difunctional silane. The invention also relates to a modified polymer obtainable by this method, as well as a polymer modified with functions or pendant groups regularly distributed along the chains.

There are various ways to obtain polymers with pendent functions or groups along the chain known to those skilled in the art.

A first method of obtaining is to carry out an anionic polymerization in which the living polymer reacts with a functionalizing agent.

Document FR 3009560 thus describes the preparation of a functionalized polymer in the middle of the chain by anionic polymerization involving an alkoxysilane functionalization agent bearing an amine function.

FR 301 1241 B 1 discloses the preparation of a functionalized polymer in the middle of the chain and at the end of the chain by anionic polymerization involving an alkoxysilane functionalization agent carrying an amine function, the anionic polymerization being initiated by a lithium amide. introducing an amine at the end of the living chain.

Document FR 3023293 also discloses the preparation of a polymer functionalized at the end of the chain by anionic polymerization involving an alkoxysilane functionalization agent.

Other known methods of obtaining polymers with functions or groups pendant along the chain are by way of for example, radical grafting or dipolar reaction 1, 3 on an unsaturated carbon-carbon bond of a polydiene.

Also known are methods for obtaining brush polymers (brush-polymer in English) iteratively or by coupling prepolymers to reactive oligomers. The distribution of the oligomers on either side of the chain along the chains thus forms a brushed polymer (Polym Chem, 2016, 7, 2079-2086 and Macromolecules, 2014, 47, 1883-1905).

However, there is a need to be able to have polymers having a regular distribution along the chain of pendant functional groups or not (these pendant groups are not oligomers).

The Applicant has discovered that this goal can be achieved by means of a preparation process comprising:

an anionic polymerization step of at least one diene monomer in the presence of a difunctional polymerization initiator, to obtain a difunctional living prepolymer comprising a reactive site at each of its two ends, and then

a reaction step of said difunctional living prepolymer comprising a reactive site at each of its two ends by polycondensation by means of a difunctional coupling agent.

The invention is therefore obj and a process for preparing a modified polymer comprising:

a reaction step of said difunctional living prepolymer comprising a reactive site at each of its two ends by polycondensation using a difunctional coupling agent of following formula (I) R ₂

Y - Si - z

^R 1

(I) where

Y, Z independently designate a reactive function with respect to the living prepolymer,

R1 and R2 independently denote a saturated or unsaturated, preferably saturated, linear, branched or cyclic hydrocarbon group which may optionally contain one or more heteroatoms, R1 and R2 being free of a site which is reactive with the difunctional living prepolymer,

the molar ratio r = n (difunctional living prepolymer) / n (coupling agent) ranging from 0.85 to 1.25.

By diene monomer is meant a monomer bearing two carbon-carbon double bonds, conjugated or otherwise.

Preferably, the diene monomer (s) are conjugated.

According to a first embodiment, the anionic polymerization step is a homopolymerization of a conjugated diene monomer, preferably having from 4 to 12 carbon atoms.

According to a second embodiment, the anionic polymerization step is an anionic copolymerization of at least one conjugated diene monomer with one or more conjugated diene monomers and / or with one or more vinylaromatic monomers having from 8 to 20 carbon atoms.

Suitable conjugated dienes are in particular isoprene, 1,3-butadiene, piperylene, 1-methylbutadiene, 2-methylbutadiene, 2,3-dimethyl-1,3-butadiene, 2,4-dimethyl 1,3-butadiene, 1,3-pentadiene, 2-methyl-1,3-pentadiene, 3-methyl-1,3-pentadiene, 4-methyl-1,3-pentadiene, 2, 3-dimethyl-1,3-pentadiene, 2,5-dimethyl-1,3-pentadiene, 2-methyl-1,4-pentadiene, 1,3-hexadiene, 2-methyl-1,3 hexadiene, 2-methyl- 1,5-Hexadiene, 3-methyl-1,3-hexadiene, 4-methyl-1,3-hexadiene, 5-methyl-1,3-hexadiene, 2,5-dimethyl-1,3- hexadiene, 2,5-dimethyl-2,4-hexadiene, 2-neopentyl-1,3-butadiene, 1,3-cyclopentadiene, methylcyclopentadiene, 2-methyl-1,6-heptadiene, 1, 3-cyclohexadiene, 1-vinyl-1,3-cyclohexadiene, and a mixture of these conjugated dienes; preferably, these conjugated dienes are chosen from isoprene, butadiene and a mixture containing isoprene and / or butadiene. More preferably, the conjugated diene monomer is butadiene.

As vinylaromatic compounds are especially suitable styrenic monomers, namely methylstyrenes, para-tert-butylstyrene. Preferably, the vinylaromatic monomer is styrene.

The difunctional polymerization initiator usable according to the invention in the anionic polymerization step may be any difunctional organic compound which will react with the diene monomer to form a difunctional prepolymer. Difunctional anionic initiators are known to those skilled in the art.

The difunctional polymerization initiator that can be used according to the invention can thus be chosen from organometallic compounds comprising two carbon-metal bonds, such as the organolithium, organopotassium, organocesium and organosodium compounds. In a preferred embodiment, the difunctional anionic initiator is a dilithiated compound.

Preferably, the difunctional polymerization initiator is a dilithiated aromatic compound resulting from the reaction of an organolithium, in particular s-butyllithium, on a dialkenyl aromatic compound.

Preferably, the organolithium is s-butyllithium.

Preferably, the dialkenyl aromatic compound is a dialkenyl benzene.

More preferably, the polymerization initiator is a reaction adduct of s-butyllithium on a dialkenyl benzene such as diisopropenylbenzene or divinylbenzene. Advantageously, such a polymerization initiator is prepared by reacting in an aliphatic or alicyclic hydrocarbon solvent a first reagent consisting of a dialkenyl benzene and a second reagent consisting of s-butyllithium, the ratio of the number of moles of dialkenyl benzene to butyl secondary lithium being substantially equal to 0.5.

The process for obtaining such a polymerization initiator is described in particular in document WO 02/020623.

As a polymerization initiator for use in the process according to the invention, mention may be made of 1,3-bis (1,3-dimethylpentyl) benzene dilithium complex.

The anionic polymerization step is preferably carried out in an aliphatic or alicyclic hydrocarbon solvent. As the aliphatic polymerization solvent, it is possible, for example, to use cyclohexane or also methylcyclohexane.

The polymerization reaction can be carried out in the presence or absence of an ether-type polar agent, for example tetrahydrofuran, or of the amine type, for example tetramethylenediamine.

The polymerization temperature can generally vary from

0 ° C to 90 ° C, and preferably 20 ° C to 70 ° C.

Advantageously, the anionic polymerization reaction is conducted in such a way that the difunctional living prepolymer obtained at the end of this polymerization stage has an average molar mass of between 2 and 40 kg / mol.

As explained above, after the anionic polymerization step described above, the method according to the invention comprises a reaction step of the difunctional living prepolymer comprising a reactive site at each of its two ends by polycondensation using a difunctional coupling agent. of formula (I) below R ₂

Y - Si - z

^R 1

(I) where

R1 and R2 independently denote a hydrocarbon group, linear, branched or cyclic, saturated or unsaturated, preferably saturated, may optionally contain one or more heteroatoms, R1 and R2 being free of reactive site vis-à-vis the living prepolymer.

By heteroatom is meant more particularly a nitrogen atom or an oxygen atom.

Preferably, R 1 and R 2 independently contain 1 to 20 carbon atoms.

By group containing a heteroatom is meant in the sense of the present invention a functional group comprising at least one heteroatom chosen from N, O. It is possible, by way of example, to mention among these functions the primary protected or secondary protected or tertiary amines, cyclic or not, imines, ethers and polyethers.

Thus, as secondary or tertiary amine functional groups, mention may be made of amines substituted with C 1 -C 10 alkyl radicals, preferably C 1 -C 4 alkyl radicals, more preferentially a methyl or ethyl radical, or else cyclic amines. forming a heterocycle containing a nitrogen atom and at least one carbon atom, preferably 2 to 6 carbon atoms. For example, the methylamino-, dimethylamino-, ethylamino-, diethylamino-, propylamino-, dipropylamino-, butylamino-, dibutylamino-, pentylamino-, dipentylamino-, hexylamino-, dihexylamino-, hexamethyleneamino- groups, preferably the diethylamino groups, are suitable. and dimethylamino. As an imine function, mention may be made of ketimines. For example, (1,3-dimethylbutylidene) amino-, (ethylidene) amino-, (1-methylpropylidene) amino-, (4-N, N-dimethylaminobenzylidene) amino-, (cyclohexylidene) amino-, dihydroimidazole and imidazole.

Preferably, Y and Z independently denote a halogen or an alkoxy group.

According to a first preferred embodiment, Y and Z are identical and represent a halogen.

Preferably, the halogen is chlorine.

According to a second preferred embodiment, Y and Z are identical and represent an alkoxy group.

Preferably, the alkoxy group is an alkoxy group having 1 to 4 carbon atoms, more preferably a methoxy or ethoxy group.

The coupling agent according to the invention is difunctional. Advantageously, the use of such a difunctional coupling agent for the polycondensation reaction makes it possible to maintain good control of the polycondensation reaction. Indeed, the use of coupling agent having more than two reactive sites vis-à-vis the living diene elastomer leads to a rapid precipitation of product (elastomeric network) in the medium which hampers the good control of the reaction. Moreover, this type of product also impairs the implementation of the polymer or the composition containing it, the formed networks creating inhomogeneous zones within the compositions. This is all the more accentuated when high molecular weights are targeted. Thus, according to the invention, the use of a difunctional coupling agent makes it possible to obtain linear polymers of high molecular mass having a regular distribution along the chain of functional or non-functional pendant groups according to a controlled synthesis method and reproducible.

For example, as coupling agent comprising an amine, the (N, N-dialkylaminopropyl) alkyl dialkoxysilanes and the alkylaminopropyl) alkyldialkoxysilanes whose secondary amine function is protected by a trialkyl silyl group and aminopropylalkydialkoxysilanes whose primary amine function is protected by two trialkyl silyl groups. The alkyl substituents present on the nitrogen atom are linear or branched and advantageously have from 1 to 10 carbon atoms, preferably 1 to 4, more preferably 1 or 2. For example, metylamino groups are suitable as alkyl substituents. -, dimethylamino-, ethylamino-, diethylamino, propylamino-, dipropylamino-, butylamino-, dibutylamino-, pentylamino-, dipentylamino, hexylamino, dihexylamino, hexamethyleneamino, preferably the diethylamino and dimethylamino groups. The alkoxy substituents are linear or branched and generally have 1 to 10 carbon atoms, or even 1 to 8, preferably 1 to 4, more preferably 1 or 2.

Preferably, the coupling agent may be chosen from 3- (N, N-dialkylaminopropyl) alkyl dialkoxysilanes, the alkyl group on the silicon atom being the methyl or ethyl group and the alkoxy group being the methoxy or ethoxy group.

Preferably, the coupling agent may be chosen from 3- (N, N-alkyltrialklsilylaminopropyl) alkyl dialkoxysilanes, the alkyl group on the silicon atoms being the methyl or ethyl group and the alkoxy group being the methoxy or ethoxy group.

Preferably, the coupling agent may be chosen from 3- (N, N-bistrialkylsilylaminopropyl) alkyl dialkoxysilanes, the alkyl group on the silicon atoms being the methyl or ethyl group and the alkoxy group being the methoxy or ethoxy group.

For example, N- (1,3-dimethylbutylidene) -3- (dimethoxymethylsilyl) -1-propanamine, N- (1, 3-methylethylidene) -3-, may be mentioned as a coupling agent comprising an imine functional group. (dimethoxymethylsilyl) -1-propanamine, N-ethylidene-3

(dimethoxymethylsilyl) -1-propanamine, N- (1-methylpropylidene) -3- (dimethoxymethylsilyl) -1-propanamine, N- (4-N, N-) dimethylaminobenzylidene) -3- (dimethoxymethylsilyl) -1-propanamine, N- (cyclohexylidene) -3- (dimethoxymethylsilyl) -1-propanamine, N- (3-dimethoxymethylsilylpropyl) -4,5-dihydroimidazole and N- (3-dimethylaminobenzylidene) dimethoxymethylsilylpropyl) -4,5-imidazole.

The coupling agent may also be chosen from functional silane coupling agents Si (OMe) ₂ Me-alkyl-O-alkyl or Si (OEt) ₂ Me-alkyl-O-alkyl, preferably compounds where the alkyl group -O-alkyl is a polyethylene glycol of formula - (CH ₂ -CH ₂ -O) _n - or a polypropylene glycol of formula - (CH ₂ -CH (CH ₃ ) -O) _n - with n = 3 to 20.

Advantageously, the molar ratio r = n (living prepolymer) / n (coupling agent) varies from 1 to 1, when the functions of the coupling agent are of halogen type, and preferably from 0.85 to 1 when the functions of the coupling agent are of the alkoxy type.

The coupling temperature is preferably between 40 and 1 20 ° C, preferably between 60 and 90 ° C and more preferably between 70 and 90 ° C. The coupling time depends on the temperature, and is between 1 and 120 minutes, preferably from 5 to 90 minutes, more preferably of the order of 60 minutes.

The polycondensation step is advantageously carried out until the polycondensed polymer reaches an average molar mass of between 40 and 250 kg / mol, more preferably between 60 and 250 kg / mol.

According to the variants of the invention according to which the coupling agent carries a protected primary or secondary amine function, the synthesis process may be continued by a step of deprotection of the primary or secondary amine. This step is implemented after the modification reaction. By way of example, it is possible to react the functionalized chains with the protected amine group with an acid, a base, a fluorinated derivative such as tetrabutylammonium fluoride, a silver salt such as silver nitrate, etc. to deprotect this amine function. These different methods are described in the book "Protective Groups in Organic Synthesis, Green TW, PGM Wuts, Third Edition, 1999". The method of synthesis of the modified polymer according to the invention can be continued in a manner known per se by the recovery steps of the modified polymer.

The modified polymer generally has an average molar mass of between 40 and 250 kg / mol, more preferably between 60 and 250 kg / mol.

Another object of the invention is a modified polymer that can be obtained by the process according to the invention.

Finally, the invention is obj and a modified polymer having an average level of functions or pendant groups ranging from 0.1 mol% to 3 mol% regularly distributed along the polymer chains. Within the meaning of the invention, along the chain also includes positioning at the end of the chain.

Examples

characterizations

- High Resolution SEC analysis (SEC / HR) for Mn and Ip, as well as for coupled chain percentages

The apparatus used is a "WATERS alliance" chromatograph. The elution solvent is (tetrahydrofuran + 1% diisopropylamine + 1% triethylamine), the flow rate of 0.2 ml / min, the temperature of the system of 35 ° C and the analysis time of 200 min. A set of three SHODEX columns in series, of trade names "KF805" is used.

The injected volume of the solution of the polymer sample is 50 μL. The detector is a differential refractometer "WATERS 2410" and the chromatographic data exploitation software is the "WATERS EMPOWER" system.

The calculated peak molar masses relate to a calibration curve made from commercial standard polystyrene "PSS READY CAL-KIT". Mass percentages the different peaks observed are determined with respect to peak heights.

The values of Mn have been recalculated on the basis of chromato grams.

Synthesis of the di-lithiated initiator 1,3-bis (1,3-dimethylpentylbenzene dilithium complex

Example of procedure for a total solution volume of 200 μL and a targeted concentration of C ^~ Li ⁺ of 1 mol / L.

In an inert reactor introduce 16.6 mL of methylcyclohexane previously bubbled. Then add 146 mL (204 mmol) of a solution of s-BuLi at 1, 4 mol / L in cyclohexane. Stir for 10 minutes.

Add 17.1 mL (100 mmol) of 1,3-diisopropenylbenzene (or 1,3-DIB) previously bubbled and stir again for 10 minutes, then introduce 15 mL (100 mmol) of TMED. Stir at 50 ° C for 4 hours.

The title of the solution is measured by Gilman assay (article J.

Am. Chem. Soc. 66, 15, 1944). The title obtained is 0.925 mol / L for a title aimed at 1 mol / L.

Synthesis of mol and 10,000 g / mol prepolymers and modified polymers

Example for a Prepolymer of Mn Target = 20000 g / mol

In an inert reactor, introduce 67.5 mL of previously bubbled methylcyclohexane, add 5 g of 1,3-butadiene. After neutralization of the impurities present in the reaction medium with butyl lithium, introduce a volume of complex dilithium 1,3-bis (1,3-dimethylpentyl) benzene dilithium initiator corresponding to 500 pmol of carbon-lithium bonds. The polymerization is carried out at 40 ° C. After total conversion of the monomer, the prepolymer is obtained. The addition of the functionalization agent (coupling agent) or methanol (2 mL of 2 mol / L solution of methanol in toluene) is then produced to obtain the final polymer (modified polymer according to the invention) or the control polymer respectively.

The polymers are antioxidized by addition of 2,2'-methylene bis-4 methyl-6 tert-butylphenol (0.4 g per 100 g of monomer). The polymers are then dried at 60 ° C under reduced pressure.

The molar mass obtained on the control prepolymer is

18058 g / mol for a target molar mass of 20000 g / mol. The polydispersity index (Ip) obtained is 1.05.

Example for a Prepolymer of Mn Target = 10000 g / mol

In an inert reactor, introduce 67.5 mL of previously bubbled methylcyclohexane, add 5 g of 1,3-butadiene. After compensation for the impurities present in the reaction medium with butyl lithium, introduce a volume of dilithium initiator 1,3-bis (1,3-dimethylpentyl) benzene dilithium complex corresponding to 1000 pmol of carbon-lithium bonds. The polymerization is carried out at 40 ° C.

After total conversion of the monomer, the prepolymer is obtained. The addition of the functionalizing agent (coupling agent) or of methanol (2 ml of 2 mol / l solution of methanol in toluene) is produced to obtain the final polymer (polymer modified according to the invention) or the control polymer respectively.

The polymers are antioxidized by the addition of 2,2'-methylene bis-4 methyl-6 tert-butylphenol (0.4 g per 100 g of monomer). The polymers are then dried at 60 ° C under reduced pressure.

The molar mass obtained on the control prepolymer is 8619 g / mol for a target molar mass of 10000 g / mol. The polydispersity index is 1, 10. Influence of ratio r and coupling temperature on functionalization

In the reactor containing a BR prepolymer (polybutadiene) having at each end a carbon-lithium bond, introduce the volume of coupling agent corresponding to the value of r (living prepolymer / coupling agent molar ratio). After a determined time at a given temperature, the polymer is protonated by adding 2 mL of 2 mol / L solution of methanol in toluene.

Samples 001-T and 002-T correspond to control polymers.

The other samples are modified polymers according to the invention and are obtained by coupling of the control prepolymers.

Methoxysilane functionalization agent: 3-Dimethylaminopropyl (dimethoxy) methylsilane

1) Variation of ratio r

2) Variation of the coupling temperature

Chlorosilane functionalization agent (dimethyldichlorosilane)

1) Variation of ratio r

Claims

1. A process for preparing a modified polymer comprising:

a reaction step of said difunctional living prepolymer comprising a reactive site at each of its two ends by polycondensation using a difunctional coupling agent of formula (I) below,

R ₂

Y - Si - Z

^R 1

(I) where

R 1 and R 2 independently denote a saturated or unsaturated, preferably unsaturated, linear, branched or cyclic hydrocarbon group which may optionally contain one or more heteroatoms, R 1 and R 2 being free of a site which is reactive with the difunctional living prepolymer,

2. Method according to claim 1 characterized in that the living prepolymer has an average molar mass of between 2 and 40 kg / mol.

3. Method according to any one of the preceding claims characterized in that the anionic polymerization step is a homopolymerization of a conjugated diene monomer.

4. Method according to any one of claims 1 to 2 characterized in that the anionic polymerization step is an anionic copolymerization of at least one conjugated diene monomer with one or more conjugated diene monomers and / or with one or more monomers vinylaromatic compounds having 8 to 20 carbon atoms.

5. Method according to claim 3 or 4 characterized in that the conjugated diene monomer is butadiene.

6. Method according to claim 4 or 5 characterized in that the vinylaromatic monomer is styrene.

7. Process according to any one of the preceding claims, characterized in that the difunctional polymerization initiator is an aromatic dilithium compound resulting from the reaction of an organolithium, in particular s-butyllithium, with a dialkenyl aromatic compound, preferably a reaction adduct of s-butyllithium on a dialkenylbenzene.

8. Process according to any one of the preceding claims, characterized in that Y and Z independently designate a halogen or an alkoxy group.

9. The method of claim 8 characterized in that Y and Z are identical and represent a halogen such as chlorine.

10. Process according to claim 8 characterized in that Y and Z are identical and represent an alkoxy group such as a methoxy or ethoxy group.

1 1. Process according to any one of the preceding claims, characterized in that the molar ratio r = n (difunctional living prepolymer) / n (coupling agent) varies from 1 to 1, 25 when the functions of the coupling agent are of the type halogen, and preferably from 0.85 to 1 when the functions of the coupling agent are of the alkoxy type.

12. Process according to any one of the preceding claims, characterized in that the modified polymer has an average molar mass of between 40 and 250 kg / mol, more preferably between 60 and 250 kg / mol.

13. Modified polymer obtainable by the process defined according to any one of the preceding claims.

14. Modified polymer having an average level of functions or pendant groups ranging from 0.1 mol% to 3 mol% regularly distributed along the polymer chains.