Synthesis of functionalized polymers by desulfurization from elastomer-containing waste materials.

Abstract

The present invention relates to a method for synthesizing polymers by desulfurization from elastomer-containing waste, said method comprising the steps of: a) contacting said elastomer-containing waste with a solvent in the presence of a desulfurization agent; and b) heating the mixture produced in step a) in the presence of a desulfurization agent at a temperature between 20°C and 250°C for a period of 15 minutes to 24 hours, wherein the concentration of the desulfurization agent is such that the ratio of said desulfurization agent concentration, expressed in parts by weight (phr) per 100 weight of elastomer, to the solvent volume, expressed in ml, is greater than 0.3 phr / ml of solvent or less than 0.2 phr / ml of solvent when the method is carried out in air, or greater than 0.06 phr / ml of solvent when the method is carried out under an inert atmosphere.

Description

[Technical field]

[0001] The present invention relates to the field of processing waste materials containing elastomers of natural and / or synthetic origin, in particular rubber-containing waste materials, the majority of which are waste tyres.

[0002] The present invention relates to the treatment of waste materials containing highly vulcanised elastomers, such as waste lorry tyres. [Background technology]

[0003] Energy recovery from rubber waste is known in the art. It consists of incinerating the rubber waste to produce energy. Energy recovery is highly polluting to the environment.

[0004] Mechanical recovery of rubber waste is known in the art: this technique consists in crushing the waste to produce granules that may be used as additives in cement works or may be incorporated into certain materials.

[0005] Chemical recovery of rubber waste is also known in the art. Chemical recovery consists of pyrolysis and desulphurization. Pyrolysis consists of partial or complete decomposition of rubber waste in the presence of oxygen to obtain, among other things, pyrolysis oil. Pyrolysis of rubber waste is a very expensive process.

[0006] Devulcanization consists of breaking the crosslinks by causing the cleavage of carbon-sulfur bonds and / or disulfide crosslinks in order to partially or completely destroy the three-dimensional structure of the vulcanized rubber. Mechanical devulcanization, microwave devulcanization and chemical devulcanization are known in the art.

[0007] Mechanical devulcanization is carried out by an extrusion process, which causes non-selective cleavage of disulfide cross-links and also breaks the carbon-carbon bonds of the polymer chains.

[0008] Microwave devulcanization aims to break carbon-sulfur bonds or disulfide cross-links by specific microwave radiation. However, and especially when carbon black is present in the rubber waste composition, as in the case of waste tires, the method causes a very significant temperature rise of the waste within a few seconds. This rapid temperature rise causes the scission of carbon-carbon bonds in the polymer chains.

[0009] Finally, chemical devulcanization of rubber waste is known, either by disulfide metathesis or by cleavage of disulfide cross-links using desulfurizing agents.

[0010] The main drawback of metathesis is that it is not possible to achieve a high degree of desulfurization since metathesis is a reversible reaction.

[0011] Desulfurization by breaking disulfide bridges using a desulfurizing agent has the advantage of low energy consumption. However, this method still has limitations related to the relatively low degree of desulfurization achieved and the lack of selectivity of the method. The main limitation of this technique is the very low degree of desulfurization obtained when the degree of vulcanization of the devulcanized rubber is high.

[0012] Regarding chemical desulfurization, the following literature is known: Rooj S., Maji PK, Basak GC, Bhowmick AK, Journal of Polymers and the Environment, (Germany), 2011, Vol.19, p.382-390; and Zohuri G., Asadi S., Kariminejad M., Mortazavi SM, Chenar MP, Sabzekar M., Polymer Degradation and Stability, (Netherlands), 2015, Vol.118, p. 88-95.

[0013] The aim of the present invention is to overcome the above mentioned drawbacks and in particular to propose a method for the synthesis of polymers by desulfurization of elastomer-containing waste materials.

[0014] Another object is to propose a method for polymer synthesis by desulfurization of elastomer-containing waste materials, which shows a high degree of desulfurization.

[0015] Another objective is to propose a method for selective polymer synthesis by desulfurization of elastomer-containing waste materials, which allows control of the microstructure of the resulting polymer.

[0016] Another objective is to propose a method for the synthesis of polymers by devulcanization of elastomer-containing wastes, which makes it possible to achieve a high degree of devulcanization starting from highly vulcanized rubber wastes.

[0017] Another objective is to propose a method for the synthesis of polymers by desulfurization of elastomer-containing waste materials, which allows the synthesis of functionalized polymers. Summary of the Invention

[0018] [Presentation of the present invention] To this end, according to a first aspect of the present invention, a method for polymer synthesis by desulfurization from elastomer-containing waste is proposed. The method according to the invention comprises the steps of: a) contacting the elastomer-containing waste material with a solvent in the presence of a desulfurization agent; b) heating the mixture obtained in step a) at a temperature between 20° C. and 250° C. for a period between 15 minutes and 24 hours. Includes.

[0019] Thus, according to a first aspect of the present invention, the desulfurizing agent, designated DA, is a radical initiator, for example, the desulfurizing agent is a desulfurizing agent for a crosslinking point having a sulfur atom and another sulfur atom or a carbon atom bonded to the sulfur atom.

[0020] The radical initiator is capable of forming one or more radicals. Preferably, the desulfurization agent is capable of forming radicals by homolysis. More preferably, the desulfurization agent is a peroxide.

[0021] According to a first aspect of the present invention, - The radical initiator is represented by the formula (1) [ka] wherein R and R' are the same or different and each is independently a substituent that provides a mesomeric effect of a donor group or a mesomeric effect of a withdrawing group or an inductive effect of a donor group or an inductive effect of a withdrawing group; or - The concentration of the desulfurizing agent is the ratio of the concentration of the desulfurizing agent expressed in parts by weight (phr) per 100 parts by weight of elastomer to the volume of the solvent expressed in ml. greater than 0.3 phr / ml for the solvent or less than 0.2 phr / ml for the solvent if the method is carried out in air; Greater than 0.06 phr / ml for solvents if the method is carried out under an inert atmosphere Either that or

[0022] According to the present invention, R and R', which provide the mesomeric effect of the donor group, the mesomeric effect of the withdrawing group, the inductive effect of the donor group, or the inductive effect of the withdrawing group, are independently hydrogen (-H), halogen atoms selected from iodine, bromine, fluorine and chlorine, (C 1‐18 ) alkyl groups, primary amines (-NH2), secondary amines (-NHRa1, where Ra1 is selected from (C1-C5) alkyl groups and aromatic rings) or tertiary amines (-NRa1Ra2, where Ra1 and Ra2 may be the same or different and each may be independently a (C1-C5) alkyl group or an aromatic ring), hydroxyl (-OH), alcoholates (or salts) (Ra1-O -where Ra1 is selected from (C1-C5) alkyl groups and aromatic rings), (C1-C5) alkoxy groups, thiols (-SH), thioethers (-SRa1, where Ra1 is selected from (C1-C5) alkyl groups and aromatic rings), thiolates (or salts) (Ra1-S - ), where Ra1 is selected from a (C1-C5) alkyl group and an aromatic ring), an aromatic ring, a conjugate base of a carboxylic acid (—COO - ), carboxyl group (-COOH), ester (-CO2Ra1, where Ra1 is selected from (C1-C5) alkyl groups and heterocycles), aldehyde group (-CHO), carbonyl (-COR), nitro group (-NO2), nitrile group (-CN), sulfonyl group (-SO2-), Sulfonates The group is selected from the group comprising a group (salt or acid) (-SO3), a sulfone (-SO2R), a phosphate group -O-PO (ORa1) (ORa2), where Ra1 and Ra2 may be the same or different and each may be independently of each other a hydrogen or a (C1-C5) alkyl group or an aromatic ring), a primary amide group (-CONH2), a secondary amide group (-CONHRa1, where Ra1 is selected from a (C1-C5) alkyl group and an aromatic ring) or a tertiary amide group (-CONRa1Ra2, where Ra1 and Ra2 may be the same or different and each may be independently of each other a (C1-C5) alkyl group or an aromatic ring).

[0023] (C1‐C 18 The term (C1-C2) alkyl denotes any straight or branched carbon chain having 1 to 18 carbon atoms, including all alkyl groups having 1 to 18 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, neopentyl, isopentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl and octadecyl groups. 18) Alkyl groups include carbon chains with 1 to 8 carbon atoms, i.e. (C1-C8) alkyl groups, in particular methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, neopentyl, isopentyl, hexyl, heptyl, octyl groups, more preferably carbon chains with 1 to 5 carbon atoms, i.e. (C1-C5) alkyl groups, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, neopentyl, isopentyl groups, and more preferably carbon chains with 1 to 3 carbon atoms, i.e. (C1-C3) alkyl groups, in particular methyl, ethyl, n-propyl and isopropyl groups.

[0024] The term (C1-C5) alkyl refers to any straight or branched carbon chain having 1 to 5 carbon atoms, including all alkyl groups having 1, 2, 3, 4 or 5 carbon atoms, in particular methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, neopentyl and isopentyl groups. The term (C1-C5) alkoxy refers to O-(C1-C5) alkyl groups, where the (C1-C5) alkyl groups are as defined above. Examples include methoxy, ethoxy, butoxy and pentoxy groups.

[0025] The term aromatic ring includes aryl groups, in particular phenyl, benzyl, naphthyl, biphenyl and tetrahydronaphthyl groups, as well as heterocyclic rings, i.e. rings which, in addition to carbon atoms, also contain heteroatoms such as nitrogen, oxygen and sulfur, etc. Thus, examples of heterocyclic rings include benzimidazolyl, furyl, imidazolyl, piperazinyl, piperidinyl, pyranyl, pyrazinyl, pyrroazolidinyl, pyrazolinyl, pyrazolyl, pyridazinyl, pyridooxazole and pyridoimidazole.

[0026] Preferably, R and R' each independently represent a hydrogen atom, a fluorine atom, a methoxy group or an acetoxy group.

[0027] Even more preferably, R and R' are the same and each represents a fluorine atom, a methoxy group, or an acetoxy group.

[0028] When the radical initiator is a compound of formula (1), the polymer obtained by carrying out the method is a functionalized polymer.

[0029] In an advantageous embodiment of the first aspect of the invention, the radical initiator is a compound of formula (1) The concentration of the desulfurizing agent is such that the ratio of the desulfurizing agent concentration expressed in parts by weight per 100 weight of elastomer (phr) to the solvent volume expressed in ml is: greater than 0.3 phr / ml for the solvent or less than 0.2 phr / ml for the solvent if the method is carried out in air; Greater than 0.06 phr / ml for solvents if the method is carried out under an inert atmosphere It looks like this.

[0030] Advantageously, R, R' or both are other than hydrogen atoms. In other words, R and R' are both other than hydrogen atoms, or R is other than hydrogen atoms, or R' is other than hydrogen atoms. In other words, R and R' are not hydrogen atoms at the same time.

[0031] The process according to the invention makes it possible to obtain polymers. Preferably, the process according to the invention makes it possible to obtain polymers, in particular elastomers.

[0032] According to the present invention, the resulting polymer has the formula 2 and / or formula 2' [ka] A functionalized polymer of the formula: In the above formula, R and R' may be the same or different and are as defined above; x is an integer between 0 and 6, preferably equal to 0, 1, 2, 3, 4, 5 or 6; n is an integer between 6 and 600. The number n represents the number of units, each bearing a functional group, that are inserted along the polymer chain during desulfurization.

[0033] Conveniently, R and R' are other than hydrogen atoms.

[0034] Unlike conventional methods in which one or more functional groups are inserted only at the ends of the polymer chain, one or more functional groups are inserted into the interior of the polymer chain. Thus, the method of the present invention allows one or more functional groups to be inserted into the interior of the polymer chain, resulting in a functionalized polymer of formula 2 and / or formula 2'.

[0035] The method according to the invention is based on the synthesis of polymers by desulfurization of crosslinking points present in the waste from which the method is carried out. Crosslinking points comprise at least one sulfur atom and another sulfur atom or carbon atom bonded to the sulfur atom. Such crosslinking points are present in particular in elastomers. Thus, according to the invention, by elastomer-containing waste is meant waste that contains sufficient elastomers such that the amount of polymer synthesized after the method is carried out is sufficient and recoverable. Based on his general knowledge, the skilled person will be able to determine from the elastomer content in the waste to be treated whether the synthesis of polymers by carrying out the method of the invention is justified.

[0036] According to the present invention, waste containing at least 10 wt. %, preferably at least 30 wt. %, of elastomer based on the total weight of the waste, has a sufficient concentration for polymer synthesis by desulfurization according to the present invention, starting from said waste.

[0037] According to the present invention, the elastomer-containing waste material is - polyisoprene and / or polybutadiene, and / or - butadiene acrylonitrile (Nitrile Butadiene Rubber or NBR), and / or - styrene-butadiene (Styrene-Butadiene Rubber SBR), and / or - may contain ethylene-propylene diene monomer (Ethylene Propylene Diene Monomer or EPDM); and / or - It may be natural rubber (NR) and / or butyl rubber waste.

[0038] Preferably, the elastomer-containing waste material may be waste truck tires, which are elastomer waste materials with a high degree of vulcanization. By "high degree of vulcanization" is meant 10 -4 Higher than 10 mol / ml, preferably 10 -3 It is an elastomer with a crosslink density higher than 100 mol / ml.

[0039] As a non-limiting example, if the waste material is scrap tires, once the metal components have been removed, the waste material essentially contains elastomers called rubber and carbon black called filler.

[0040] According to a particular embodiment of the invention, the waste tires used are pre-shredded tires, shreds, crumb rubber or granules, preferably crumb rubber or granules.

[0041] Preferably, when the method is carried out in air, the concentration of the desulfurization agent is Between 0.3 phr / ml of the solvent and the concentration value (phr / ml of the solvent) at which the solubility limit of DA in the solvent is reached, or ● Less than 0.2 phr / ml for solvents It is.

[0042] A person skilled in the art will be able to apply his general knowledge and the teachings of this document to determine the maximum concentration of DA that is possible or suitable for use. Similarly, if the concentration of DA is less than 0.2 phr / ml of the solvent, a person skilled in the art will be able to apply his general knowledge and the teachings of this document to determine the minimum concentration of DA that is possible or suitable for use.

[0043] More preferably, when the method is carried out in air, the concentration of DA is ● 0.3phr / ml to 8phr / ml of solvent, or ● Less than 0.2 phr / ml for solvents It is.

[0044] More preferably, when the method is carried out in air, the concentration of DA is ● 0.3phr / ml to 0.6phr / ml of solvent, or ● Less than 0.2 phr / ml for solvents It is.

[0045] Preferably, when the method is carried out under argon, the concentration of DA is comprised between 0.06 phr / ml of the solvent and the concentration value (phr / ml of the solvent) at which the solubility limit of DA in the solvent is reached.

[0046] More preferably, when the method is carried out under an inert atmosphere, the concentration of DA is comprised between 0.06 phr / ml and 8 phr / ml of the solvent.

[0047] More preferably, when the method is carried out under an inert atmosphere, the concentration of DA is comprised between 0.06 phr / ml and 0.6 phr / ml of the solvent.

[0048] According to the invention, by "inert atmosphere" is meant an atmosphere that is non-reactive under the conditions under which the method is carried out. Non-limiting examples include atmospheres that are mainly composed of nitrogen and / or noble gases, such as argon. Preferably, the atmosphere is composed of nitrogen and / or noble gases.

[0049] Preferably, step b of the process is carried out at a temperature of the mixture between 20° C. and 150° C., more preferably between 40° C. and 120° C., even more preferably between 60° C. and 100° C. Most preferably, the process is carried out at a temperature of 80° C.

[0050] The heating time is preferably 1 to 8 hours, more preferably 1 to 6 hours.

[0051] Preferably, R and R' are selected from groups containing one or more carbon and / or oxygen and / or nitrogen and / or phosphorus and / or sulphur and / or halogen atoms.

[0052] The polymers synthesized by the method of the invention may consist of a mixture containing polymers and oligomers. Preferably, the polymers synthesized are oligomers. According to the invention, said oligomers are considered to be chains of monomers with a molar mass of less than 2000 g / mol.

[0053] According to the invention, the solvent may be an organic solvent or an ionic liquid or a deep eutectic solvent or a mixture thereof. By way of example, the ionic liquid may be selected from the phosphonium, imidazolium or pyridinium series. The ionic liquid according to the invention is composed of an anion and a cation and has the following general formula: [ka] wherein: - A n- PF6 - , NO3 - , F, Cl - , Br - , I- , R 9 SO3 - , R 9 OSO3 - , R 9 CO3 - , CF3SO3 - , BF4 - , B(R 9 )4 - , CF3CO2 - , R 9 PO2 - , (CF3SO2)N - , CH3SO3 - , (C 12 H 25 )C6H4SO3 - , R 9 CO2 - an anion selected from the group comprising: R 9 is selected from the group consisting of substituted or unsubstituted alkyl, substituted or unsubstituted aryl, and alkoxy; n is equal to 1, 2, or 3 depending on the negative charge of said anion, (1 / n) being equal to 1 if the anion has one negative charge, 1 / 2 if the anion has two negative charges, and 1 / 3 if the anion has three negative charges; X is a nitrogen atom, a phosphorus atom, or a sulfur atom, provided that when X is a sulfur atom, R 1 , R 2 , R 3 , R 4 At least one of the groups is absent, - R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 may be the same or different and each is selected from the group consisting of hydrogen, halogen, alkoxy, substituted or unsubstituted alkyl, substituted or unsubstituted aryl, and R 1 -R 2 , R 2 -R 3 , R 3 -R 4 , R 4 -R 5 , R5 -R 6 , R 6 -R 7 , R 7 -R 8 or R 8 -R 1 may correspond to a ring with 5, 6 or 7 carbon atoms, -Z 1 , Z 2 , Z 3 may be the same or different and are selected from the group containing carbon and nitrogen atoms, with the proviso that Z 1 , Z 2 and Z 3 At least one of the atoms represents a nitrogen atom, and Z 1 , Z 2 and Z 3 If one of the atoms in is a nitrogen atom, the corresponding group R 1 , R 2 , R 3 does not exist.

[0054] These ionic liquids are described in French patent application FR 3 014 104, pages 9 to 15.

[0055] The deep eutectic solvent according to the present invention comprises: - mixtures of quaternary ammonium salts and metal chlorides; a non-limiting example of such a mixture is a mixture of 1-ethyl-3-methylimidazolium and aluminum chloride (AlCl3); - mixtures of quaternary ammonium salts and hydrates of metal chlorides, - a mixture of a quaternary ammonium salt and a hydrogen bond donor; a non-limiting example is where the hydrogen bond donor is urea or a urea derivative; - a mixture of a metal chloride hydrate and a hydrogen bond donor; a non-limiting example is where the hydrogen bond donor is urea or a urea derivative, and a non-limiting example is where the mixture is a mixture of aluminum chloride (AlCl3) and urea. can be selected from.

[0056] Preferably, the deep eutectic solvent may be a mixture of choline chloride and urea. More preferably, the deep eutectic solvent may be a mixture of 1 mol / l choline chloride and 2 mol / l urea.

[0057] Deep eutectic solvents can partially or completely include natural products among the following: aconitic acid and choline chloride mixtures, malic acid and glucose mixtures, malic acid and fructose mixtures, malic acid and sucrose mixtures, citric acid and sucrose mixtures, maleic acid and sucrose mixtures, glucose and fructose mixtures, fructose and sucrose mixtures, glucose and sucrose mixtures, maleic acid and glucose mixtures, citric acid and glucose mixtures.

[0058] The solvent may be a mixture of solvents. Preferably, the solvent is a mixture of an organic solvent and an ionic liquid, or a mixture of an organic solvent and a deep eutectic solvent.

[0059] The organic solvent is selected from aromatic or aliphatic non-polar solvents. Preferably, the organic solvent is xylene.

[0060] The heating time of the mixture may be from 1 to 12 hours if the process is carried out under an inert atmosphere.

[0061] Preferably, the mixture is heated for a period of between 2 hours and 4 hours if the process is carried out under an inert atmosphere.

[0062] More preferably, the heating time of the mixture is 3 hours when the process is carried out under an inert atmosphere.

[0063] The heating time of the mixture may be from 1 to 12 hours when the process is carried out in air.

[0064] Preferably, the heating time of the mixture is between 3 hours and 5 hours when the process is carried out in air.

[0065] More preferably, the heating time of the mixture is 4 hours when the process is carried out in air.

[0066] More preferably, when the method is carried out in air, the concentration of DA is less than 0.2 phr / ml of the solvent.

[0067] The method may include a step of activating the elastomer-containing waste material before step a) by freeze-drying or by swelling or by treatment with supercritical CO2. Swelling can be carried out in organic solvents, ionic liquids or deep eutectic solvents. Freeze-drying may be carried out directly in water, after which the water is removed by sublimation. Freeze-drying may also be carried out in a solvent other than water, in which case a step of solvent exchange from a solvent different from water is carried out prior to the step of sublimation. For treatment with supercritical CO2, the waste material is swollen in fluid CO2, and then the CO2 is removed by evaporation. A person skilled in the art can apply his general knowledge to apply the various waste material activation techniques described above.

[0068] The swelling activation step can be carried out in the same solvent as that used in carrying out the desulfurization, or in a different solvent.

[0069] Preferably, the activation step by swelling comprises: in an organic solvent having a dipole moment between 0.5 and 2.5 Debye, or - in ionic liquids, deep eutectic solvents, or by treatment with supercritical carbon dioxide It would be good if this were carried out.

[0070] Preferably, the organic solvent having a dipole moment of 0.5 to 2.5 Debye is an aprotic solvent.

[0071] Preferably, the organic solvent having a dipole moment of 0.5 to 2.5 Debye is dichloromethane (DCM) or tetrahydrofuran (THF).

[0072] If the step of activation by swelling is carried out in an organic solvent having a dipole moment between 0.5 and 2.5 Debye, said swelling step is carried out separately from the mixture, prior to desulfurization.

[0073] The method may further comprise, following step b), a step of separating the polymer obtained. This step may be carried out by any technique known to those skilled in the art, for example by filtration, centrifugation, precipitation. The liquid phase containing the polymer is recovered. In the case of waste tires, the solid phase containing the carbon black may be reused in a new formulation.

[0074] If the polymer synthesized by the method of desulfurization according to the invention consists of a mixture containing polymers and oligomers, the separation step may be carried out by - recovering the oligomer dissolved in a solvent that does not dissolve the polymer, e.g. a polar solvent, and / or - a metathesis step, which causes cleavage of carbon-carbon double bonds of a polymer that is insoluble in the solvent used to solubilize the oligomer, to form an oligomer that is soluble in said solvent; may include.

[0075] The devulcanization reaction and the rubber waste activation steps may be carried out consecutively.

[0076] Preferably, when the desulfurization reaction and the elastomer-containing waste material activation step are carried out sequentially, they are carried out simultaneously.

[0077] Preferably, when the desulfurization reaction and the elastomer-containing waste material activation step are carried out sequentially, they are carried out in a mixture.

[0078] Preferably, when the desulfurization reaction and the activation step of the elastomer-containing waste material are carried out sequentially, the solvent of the mixture is an ionic liquid or a deep eutectic solvent.

[0079] When the desulfurization reaction and the activation step of the elastomer-containing waste are carried out sequentially in an ionic liquid or deep eutectic solvent, the resulting polymer precipitates directly in the mixture.

[0080] According to the invention, the method according to the first aspect of the invention is a recycling process which allows waste materials containing elastomers to be utilised.

[0081] According to a second aspect of the present invention, a compound of formula 3 and / or formula 3' [ka] In the above, a functionalized elastomer of the formula: x is an integer from 0 to 6, preferably equal to 0, 1, 2, 3, 4, 5, or 6; n represents the number of units each having a functional group that are inserted along the polymer chain upon desulfurization and is an integer from 6 to 600; m represents the number of monomers that the polymer contains and is an integer from 6 to 600; Y is a hydrogen atom or a methyl group; R and R' may be the same or different for each unit and are selected from hydrogen (-H), halogen atoms selected from iodine, bromine, fluorine and chlorine, (C 1‐18 ) alkyl group, primary amine (-NH2), secondary amine (-NHRa1, where Ra1 is selected from (C1-C5) alkyl groups and aromatic rings) or tertiary amine (-NRa1Ra2, where Ra1 and Ra2 may be the same or different and each may be independently a (C1-C5) alkyl group or an aromatic ring), hydroxyl (-OH), alcoholate (or salt) (Ra1-O-, where Ra1 is selected from (C1-C5) alkyl groups and aromatic rings), (C1-C5) alkoxy group, thiol (-SH), thioether (-SRa1, where Ra1 is selected from (C1-C5) alkyl groups and aromatic rings), thiolate (or salt) (Ra1-S - wherein Ra1 is selected from a (C1-C5) alkyl group and an aromatic ring, an aromatic ring, a conjugate base of a carboxylic acid (-COO- ), carboxyl group (-COOH), ester (-CO2Ra1, where Ra1 is selected from (C1-C5) alkyl groups and heterocycles), aldehyde group (-CHO), carbonyl (-COR), nitro group (-NO2), nitrile group (-CN), sulfonyl group (-SO2-), Sulfonates The group is selected from the group comprising a group (salt or acid) (-SO3), a sulfone (-SO2R), a phosphate group -O-PO (ORa1) (ORa2), where Ra1 and Ra2 may be the same or different and each may be independently of each other a hydrogen or a (C1-C5) alkyl group or an aromatic ring), a primary amide group (-CONH2), a secondary amide group (-CONHRa1, where Ra1 is selected from a (C1-C5) alkyl group and an aromatic ring) or a tertiary amide group (-CONRa1Ra2, where Ra1 and Ra2 may be the same or different and each may be independently of each other a (C1-C5) alkyl group or an aromatic ring).

[0082] (C1‐C 18 The term (C1-C2) alkyl denotes any straight or branched carbon chain having 1 to 18 carbon atoms, and includes all alkyl groups having 1 to 18 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, neopentyl, isopentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl and octadecyl groups. 18) Alkyl groups include carbon chains having 1 to 8 carbon atoms, i.e. (C1-C8) alkyl groups, specifically methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, neopentyl, isopentyl, hexyl, heptyl, octyl groups, more preferably carbon chains having 1 to 5 carbon atoms, i.e. (C1-C5) alkyl groups, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, neopentyl, isopentyl groups, and more preferably carbon chains having 1 to 3 carbon atoms, i.e. (C1-C3) alkyl groups, specifically methyl, ethyl, n-propyl and isopropyl groups.

[0083] The term (C1-C5)alkyl denotes any straight or branched carbon chain having from 1 to 5 carbon atoms, and includes all alkyl groups having 1, 2, 3, 4 or 5 carbon atoms, in particular methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, neopentyl and isopentyl groups.

[0084] The term (C1-C5)alkoxy refers to an O-(C1-C5)alkyl group, where the (C1-C5)alkyl group is as defined above. Examples include methoxy, ethoxy, butoxy and pentoxy groups.

[0085] Preferably, R or R' each independently represent a hydrogen atom, a fluorine atom, a methoxy group or an acetoxy group.

[0086] According to the present invention, R and R' may be other than a hydrogen atom.

[0087] Even more preferably, R and R' represent a fluorine atom, a methoxy group or an acetoxy group.

[0088] As mentioned above, unlike the conventional methods in which one or more functional groups are only inserted at the ends of the polymer chain, one or more functional groups are inserted into the interior of the polymer chain. Thus, the method according to the present invention makes it possible to insert one or more functional groups into the interior of the polymer chain, and thus obtain functionalized polymers of formula 3 and / or formula 3'.

[0089] Formula 4 shows the general chemical structure of an elastomer. [ka]

[0090] According to a third aspect of the present invention, the use of a functionalized elastomer according to the second aspect of the present invention as a material is proposed.

[0091] Preferably, the use of the functionalized elastomer according to the second aspect of the present invention is proposed as an elastomeric material, a thermoplastic elastomer or a biomedical elastomer.

[0092] According to a fourth aspect of the present invention, a polymer composition is proposed which is obtainable by the process according to the first or second aspect of the present invention. The process of the present invention makes it possible to obtain a polymer composition. Said polymer composition may consist of an oligomer or a mixture comprising a polymer and an oligomer. The polymer composition depends on the waste material subjected to the desulfurization process according to the present invention. The polymer composition comprises an elastomer when the waste material comprises an elastomer.

[0093] According to a fifth aspect of the present invention, it is proposed to use the polymer composition obtained according to the fourth aspect of the present invention as an additive or reagent, such as a surfactant, crosslinker or chain extender, in a mixture of virgin or new elastomers.

[0094] The use of the polymer composition obtained according to the fourth aspect of the invention is proposed as a material, in particular as a thermoplastic elastomer or elastomer in the biomedical field. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0095] [Description of the embodiment] According to the embodiment presented, the desulfurization process is carried out starting from granules or crumb rubber of waste truck tires. The reversible reactions of the process of chemical desulfurization by cleavage of disulfide bridges using a desulfurization agent are shown in the following reaction schemes 1 and 1′. [ka]

[0096] This devulcanization step therefore constitutes a route for the synthesis of polymers starting from waste tyres. The type of polymer synthesized depends mainly on the degree of polymerization, in terms of chain length, of the elastomer contained in the waste from which the process is carried out. According to a described embodiment, the elastomer-containing waste from which the process is carried out originates from waste lorry tyres. Depending on the parameters used to carry out the process, the synthesis results in oligomers or a mixture comprising polymers and oligomers. The polymer obtained according to reaction scheme 1 comprises the number of units each containing a functional group inserted along the polymer chain during devulcanization, represented by n and ranging from 6 to 600, the number of sulphur atoms linking the functional group to the polymer chain, represented by x and ranging from 0 to 6, and the number of monomers the polymer contains, represented by m and ranging from 6 to 600.

[0097] It is known that waste tires of trucks have a high degree of vulcanization. The devulcanizing agent is used in an amount of about 6 wt% based on the rubber waste. Those skilled in the art will express this ratio of 6 parts of DA per 100 parts of rubber waste by weight as "phr", which stands for "per hundred rubber". The weight of the initial waste is 300 mg when carrying out each of the embodiments presented.

[0098] According to the invention, once the synthesis process is completed, a further step is carried out to recover the synthesized polymer, which consists of a Soxhlet treatment of the desulfurized waste with acetone for 24 hours to recover the functionalized polymer. When the synthesized polymer is in suspension and / or in a solvated state, the skilled person will be able to select the most appropriate separation or extraction chemical process to recover the polymer.

[0099] The degree of desulfurization achieved after carrying out the method, hereafter referred to as DDV, is determined by Flory's principle through the change in crosslink density according to the method described by Paul J. Flory and John Rehner, The Journal of Chemical Physics, (USA), 1943, Vol.11, p.521. The degree of desulfurization therefore allows the specific measurement of the cleavage products of disulfide bridges and carbon-sulfur bonds. The value of DDV therefore allows the specific evaluation of the efficiency of the desulfurization reaction. In the prior art documents, DDV is generally determined from sol-gel measurements, generally using the Soxhlet extraction method and specifically starting from the soluble fraction of the desulfurized polymer. The soluble fraction measured includes the cleavage products of disulfide bridges and carbon-sulfur bonds, but also the cleavage products of the carbon-carbon bonds of the polymer chain.

[0100] Based on the observation that rubber is mainly composed of polyisoprene and that carbon-carbon double bonds are also susceptible to free radicals, the inventors have deduced that the main source of depolymerization is the reaction of DA with the carbon-carbon double bonds of polyisoprene. Therefore, in order to accurately evaluate the selectivity of the method according to the invention, the degree of functionalization of polyisoprene contained in waste tires, hereinafter referred to as DOF, was studied in parallel under the same conditions used when carrying out the method. The polyisoprene selected for measuring the DOF has a degree of polymerization similar to that of the waste truck tires used. The value of DOF therefore allows an accurate evaluation of the specificity of the desulfurization reaction with respect to disulfide crosslinks and carbon-sulfur bonds. A process that results in a DOF of less than 30% will be considered to have an acceptable selectivity. The reversible reaction of depolymerization of polyisoprene by reaction of a desulfurizing agent with the carbon-carbon double bonds of polyisoprene or polybutadiene is shown in the following reaction scheme 2: [ka]

[0101] The reversible reaction of depolymerization of polyisoprene by reaction of a desulfurizing agent with the carbon-carbon double bonds of polyisoprene or polybutadiene can be supplemented with the following Reaction Scheme 3. [ka]

[0102] According to a first embodiment, the method for synthesizing oligomers by desulfurization is carried out in air and DA is a compound of formula 1a, which corresponds to a compound of formula 1 in which R and R′ are hydrogen atoms. [ka] is benzoyl peroxide.

[0103] The solvent used is xylene.

[0104] Table 1 shows the effect of temperature on the method according to the first embodiment. It can be seen that going from a temperature of 80° C. to a temperature of 100° C. doubles the DDV and increases the DOF by a factor of 12. This demonstrates that the depolymerization reaction is significant above 80° C. [Table 1]

[0105] Table 2 shows the effect of time on the method according to the first embodiment. Table 2 shows that the DDV increases and reaches a maximum at a reaction time of 4 hours, then slowly decreases. As for the DOF, it remains relatively stable and low. The DOF changes from 5% at reaction times of 2 and 3 hours to 7% at reaction times of 4 and 5 hours. [Table 2]

[0106] Table 3 shows the effect of the DA concentration on the process according to the first embodiment. At a concentration of 0.24 phr per milliliter of solvent, i.e. 6 wt% DA in 25 ml of solvent volume, the DDV is relatively low and the DOF is 5%. At a high concentration of 0.6 phr / ml of DA in solvent, i.e. 6 wt% DA in 10 ml of solvent volume, the DDV is 61.3% and the DOF is 82%. At a low concentration of 0.06 phr / ml of DA in solvent, i.e. 6 wt% DA in 100 ml of solvent volume, the DDV is 61.2% and the DOF is 18%. Surprisingly, the DDV obtained with the high DA concentration is similar to that obtained with the low DA concentration, when the process is carried out for exactly the same time. The high DOF observed when carrying out the process with the high DA concentration confirms the presence of a secondary depolymerization reaction. It is noteworthy that even though the selectivity is low when using the high DA concentration, the DDV is still 13.5×10 -4 The DDV obtained for highly vulcanized waste materials such as scrap truck tires with a crosslink density of 1.0 mol / ml is typically 2.6 × 10 -4The DDV is at least equal to or higher than that obtained for rubbers with a much lower crosslink density of 100 mol / ml. For low concentrations of DA, it can be seen that the method makes it possible to obtain good DDV values ​​and has a very good selectivity with a DOF of 18%. [Table 3]

[0107] According to a second embodiment, the process is carried out under an inert atmosphere, that is argon, DA is benzoyl peroxide of formula 1a and the solvent used is xylene. [ka]

[0108] Table 4 shows the effect of an inert atmosphere on the DDV according to the second embodiment. The DDV is doubled compared to the process carried out under the same conditions in air. However, the DOF is also doubled but still low. Thus, when optimal selectivity is required, it would be preferable to run the process in air, whereas when optimal desulfurization efficiency is required, it would be preferred to run the process under argon. [Table 4]

[0109] Table 5 shows the effect of time on the method according to the second embodiment. Table 5 shows that the DDV increases and reaches a maximum at a reaction time of 3 hours, then drops off rapidly. As for the DOF, it increases with time. The DOF changes from 10% at reaction times of 2 and 3 hours to 14% and then 16% at reaction times of 4 and 5 hours. [Table 5]

[0110] Table 6 shows the effect of the concentration of DA on the method according to the second embodiment. It can be seen that the decrease in the concentration of DA leads to a decrease in DDV and an increase in DOF. Thus, a value of DA concentration higher than 0.06 phr / ml for the solvent is preferred when the method is carried out under argon, in contrast to carrying out the method in air. This indicates that, in addition to the reactions of desulfurization and radical depolymerization, additional reactions appear when the method is carried out under argon. It may be, for example, the crosslinking of sulfur-containing radicals at disulfide bridges and / or double bonds of polymer chains.

[0111] It can further be seen that by carrying out the method according to the second embodiment at DA concentration values ​​of higher than 0.06 phr / ml of the solvent, DDV and DOF values ​​are obtained that are comparable or slightly better than those obtained when the method is carried out according to the first embodiment at DA concentration values ​​of less than 0.2 phr / ml of the solvent. [Table 6]

[0112] According to a particular embodiment of the method according to the invention, a step of activating the waste tire granules is carried out prior to the desulfurization reaction.

[0113] According to a first variant embodiment, the activation comprises a step of swelling the granules. Table 7 shows the effect of the type of solvent on the degree of swelling of the granules and on the proportion of the granules solubilized by the solvent. This swelling step consists of placing a given amount of granules from waste tires in a solvent for a given time and recovering the part of the waste tires solubilized by the solvent. Each experiment was carried out three times and the calculated average values ​​are shown in Table 7. Table 7 shows that the polar solvent acetone (dipole moment μ=2.86 Debye) is not effective, with a very low proportion of the waste solubilized and a very low degree of swelling. The non-polar solvent pentane (dipole moment μ=0.2D) is not very effective. However, the less polar solvents dichloromethane (DCM) (dipole moment μ=1.55D) and tetrahydrofuran (THF) (dipole moment μ=1.75D) show very efficient dissolution of the waste and swelling of the waste. This is especially true when the experiments are carried out using a Soxhlet type extractor. It is generally believed that non-polar solvents have a polar moment less than 0.5D and polar solvents have a dipole moment greater than 2D and as much as 2.5D. In terms of the protic or aprotic nature of the solvent, protic solvents would seem to be the least efficient. In fact, by comparison, ethanol (μ=1.74D), which has a dipole moment equivalent to THF and lower than acetone, swells the least and dissolves the least waste materials. [Table 7]

[0114] According to a second variant, the activation comprises a step of freeze-drying the granules. The granules are swollen in DCM for 24 hours as described in the first variant. A solvent exchange is then performed: DCM-ethanol, then ethanol-water. The water-swollen granules are then frozen and freeze-dried for 48 hours.

[0115] Table 8 shows the effect of activation by freeze drying on the devulcanization of waste tire derived granules.

[0116] When the method is carried out in air starting from freeze-dried granules, the DDV is significantly higher than that obtained with granules that have not undergone activation. The DOF remains unchanged and low.

[0117] When the method is carried out under argon starting from freeze-dried granules, the DDV is significantly reduced but the DOF remains constant. This indicates that the radical crosslinking seen when the method is carried out under argon is increased when waste tires are freeze-dried. Furthermore, when the DA concentration is reduced from 0.24 phr / ml of solvent to 0.06 phr / ml of solvent, the DDV is reduced and the DOF is increased. This also supports the results above and those shown in Table 6 that the reduced concentration of DA amplifies the radical crosslinking. [Table 8]

[0118] According to a third variant, the activation comprises a step of swelling the granules for 12 hours in trihexyltetradecylphosphonium chloride, an ionic liquid known under the trade name "Cyphos 101".

[0119] Table 9 shows the effect of carrying out the process in air starting from granules that have undergone a step of swelling in an ionic liquid. Compared to the DDV and DOF obtained without activation, the DDV increases by a factor of two and there is a clear increase in the DOF. Compared to the DDV and DOF obtained upon activation by freeze-drying, there is a perceptible increase in the DDV and there is a clear increase in the DOF. [Table 9]

[0120] According to a fourth variant, the activation comprises a step of swelling the granules by treatment with supercritical CO2 (ScCO2), which consists of treating the granules by swelling in ethanol or in acetone, followed by a solvent exchange between ethanol or acetone and ScCO2 in a dehydrator. The results of the polymer synthesis by desulfurization carried out starting from the granules swollen by treatment with ScCO2 are shown in Table 10. [Table 10]

[0121] According to another embodiment of the method according to the invention, the desulfurization agent used corresponds to formula 1, where R and R' are other than hydrogen atoms. These DAs are therefore derivatives of benzoyl peroxide (BPO). The use of said derivatives makes it possible to synthesize functionalized oligomers of formula 3 and / or formula 3' by desulfurization of rubber waste. The fact that the oligomers synthesized originate from rubber waste, as well as the fact that they are functionalized, represents an additional advantage in terms of their subsequent use. Indeed, the functional groups can include a wide choice of substituents R, R' as proposed by the invention, resulting in an easier subsequent use and a broader technical field of potential applications. Advantageously, the functional groups used BPO The derivatives correspond to formula 1, in which R and R' are identical and in the para position relative to the peroxide group. In further preferred embodiments, the derivatives correspond to formulae 1b, 1c and 1d. The compound of formula 1b contains two fluorine atoms as substituents R and R', which exert an effect on the attached aromatic ring similar to the inductive effect of an attractive group. The compound of formula 1c contains two methoxy groups (-OCH3) as substituents R and R', which exert an effect on the attached aromatic ring similar to the mesomeric effect of a donor group. The compound of formula 1d contains an acetoxy group (-C(=O)OCH3) as substituents R and R', which exert an effect on the attached aromatic ring similar to the mesomeric effect of an attractive group. [ka]

[0122] The process was carried out in air starting from granules from waste truck tires that had not undergone activation. The effect of various substituents R and R' is shown in Table 11. Each of the BPO derivatives (1b, 1c and 1d) clearly improves the DDV. Compounds 1b and 1d improve the DDV by a factor of two. Compounds 1b and 1c also lead to a significant increase in the DOF, which still remains below 30%. Compound 1d, however, reduces the DOF to 2%, thereby increasing the selectivity of the process. Surprisingly, the DDV remains significantly higher when using substituted BPO derivatives with donor or withdrawing substituents R and R', regardless of whether the electron density of the aromatic ring is increased by the effect of a substituent exerting a donor effect, or whether the electron density is drastically decreased by the effect of a substituent exerting an withdrawing effect.

[0123] This therefore makes it possible to envisage the synthesis of a wide variety of functionalised oligomers. The results obtained when compound 1d is used in carrying out the method are particularly interesting in terms of selectivity and DDV. [Table 11]

[0124] In this embodiment, other benzoyl peroxide (BPO) derivatives were used as DA. These compounds are designated as 1e, 1f, 1g, and 1h. Compound 1e has two methyl groups (-CH3) as substituents R and R', which exert a donor inductive effect on the aromatic ring to which it is attached. Compound 1f has two nitro groups (-NO2) as substituents R and R', which exert a mesomeric attracting effect on the aromatic ring to which it is attached. Compound 1g has two chlorine atoms in the ortho position as substituents R and R', which exert a attracting inductive effect on the aromatic ring to which it is attached. Compound 1h has two bromine atoms as substituents R and R', which exert a attracting inductive effect on the aromatic ring to which it is attached. [ka]

[0125] The method was carried out in air starting from unactivated waste truck tire granules. The effect of various substituents R and R' is shown in Table 12. All of the presented BPO derivatives improve the DDV significantly. Compounds 1e, 1g and 1h improve the DDV by more than 2-fold. 1g of compound also significantly increases the DOF, but the DOF still remains below 30%. Compounds 1f and 1h further reduce the DOF to 6% and 3%, respectively, thus increasing the selectivity of the process. Again, the DDV remains significantly higher when using substituted BPO derivatives bearing donor or withdrawing group substituents R and R', whether the electron density of the aromatic ring is increased by the influence of a substituent exerting a donor effect, or whether the electron density is drastically decreased by the influence of a substituent exerting an withdrawing effect.

[0126] It should be noted that for compound 1g, a reaction time of 3 hours was chosen to obtain a similar level of DDV as the other compounds presented (1b, 1c, 1d, 1e, 1f, and 1h). A reaction time of 4 hours results in a DDV similar to that obtained with compound 1a and a significant increase in DOF.

[0127] These results support the possibility of envisioning the synthesis of a wide variety of functionalized oligomers. The results obtained when compounds 1f and 1h are used in carrying out the method are particularly interesting in terms of selectivity and DDV. The results obtained when compounds 1e and 1h are used in carrying out the method are particularly interesting in terms of DDV. Compounds 1d and 1h appear to be particularly interesting due to the high DDV and low DOF (selective reaction, i.e. almost no depolymerization) that they can obtain. [Table 12]

[0128] According to a third embodiment, the solvent used when carrying out the method is the ionic liquid trihexyltetradecylphosphonium chloride, commercially available under the name "Cyphos101", the DA used is benzoyl peroxide of formula 1a, and the method is carried out in air or under an inert atmosphere. The use of ionic liquid as solvent automatically induces swelling of the waste material accompanying the desulfurization, which allows the DDV to increase as discussed above. Furthermore, the use of ionic liquid as solvent actually leads to the precipitation of the synthesized functionalized oligomers. Thus, the method can be carried out continuously and an extraction step after carrying out the desulfurization is no longer necessary.

[0129] According to the third embodiment, additional experiments were performed to illustrate the effect of the solvent. The DDV and DOF were measured after the method was carried out in the eutectic solvent choline chloride / urea, designated as 2a, and the ionic liquids "Cyphos101" designated as 2b and dioctylimidazolium bromide ([DOIM][BR]) designated as 2c, respectively. The method was carried out in air starting from granules from waste lorry tires that had not undergone any prior activation. BPO was used as the DA. The results are shown in Table 13.

[0130] In the case of "Cyphos101", extraction of the products of the desulfurization reaction was not sufficient to measure the DOF. Comparing these results with those obtained for compound 1a (BPO) in Table 11, it can be seen that the DDV is significantly higher when ionic liquids or eutectic solvents are used. Conversely, a small increase in DOF is observed when eutectic solvents are used, and a significantly larger increase when ionic liquids are used. [Table 13]

[0131] The results presented above demonstrate that the method of synthesizing polymers by desulfurization according to the invention makes it possible, among other things, to obtain functionalized polymers that may contain a large number of different substituents, a lower degree of depolymerization than is obtained with the methods commonly used, and a higher degree of desulfurization than is obtained with the methods commonly used.

Claims

1. 1. A method for synthesizing a polymer by desulfurization from elastomer-containing waste, the method comprising the steps of: a) contacting the elastomer-containing waste material with a solvent in the presence of a desulfurizing agent for desulfurizing crosslinks comprising a sulfur atom and another sulfur atom or a carbon atom bonded to the sulfur atom; b) heating the mixture obtained in step a) at a temperature between 20° C. and 250° C. for a period between 15 minutes and 24 hours; Including, The method comprises: The desulfurizing agent is represented by the formula (1) 【Chemistry 1】 wherein R and R' are the same or different and each is, independently of the other, a substituent which brings about a mesomeric effect of a donor group or a mesomeric effect of an attracting group or an inductive effect of a donor group or an inductive effect of an attracting group, and R and R' are, independently of the other, hydrogen represented by -H, a halogen atom selected from iodine, bromine, fluorine and chlorine, (C １ -C １８ ) alkyl group, -NH ２ a primary amine represented by the formula: １ (wherein Ra is a secondary amine represented by １ (C １ -C ５ ) an alkyl group and an aromatic ring, -NRa １ Ra ２ (wherein Ra is a tertiary amine represented by １ and Ra ２ are the same or different, each independently of the other (C １ -C ５ ) an alkyl group or an aromatic ring; １ -O － or a salt thereof (wherein Ra １ (C １ -C ５ ) an alkyl group and an aromatic ring, １ -C ５ ) an alkoxy group, a thiol represented by -SH, -SRa １ (wherein Ra is a thioether represented by the formula １ (C １ -C ５ ) an alkyl group and an aromatic ring, Ra １ -S － or a salt thereof (wherein Ra １ (C １ -C ５ ) an alkyl group and an aromatic ring, an aromatic ring, —COO － A conjugate base of a carboxylic acid represented by -COOH, a carboxyl group represented by -CO ２ Ra １ (wherein Ra is an ester represented by the formula: １ (C １ -C ５ ) an alkyl group and a heterocycle; an aldehyde group represented by -CHO; a carbonyl group represented by -COR; ２ a nitro group represented by -CN, a nitrile group represented by -SO ２ a sulfonyl group represented by -, -SO ３ a sulfonate group represented by the formula: ２ Sulfone represented by R, -O-PO(ORa １ ) (ORa ２ ) (wherein Ra １ and Ra ２ are the same or different, and each is independently hydrogen or (C １ -C ５ ) an alkyl group or an aromatic ring, -CONH ２ a primary amide group represented by the formula: １ (wherein Ra is a secondary amide group represented by １ (C １ -C ５ ) an alkyl group and an aromatic ring, or -CONRa １ Ra ２ A tertiary amide group represented by the formula: １ and Ra ２ are the same or different, each independently of the other (C １ -C ５ ) an alkyl group or an aromatic ring) and R is other than a hydrogen atom.

2. The concentration of the desulfurizing agent is determined by the ratio of the desulfurizing agent concentration expressed in parts by weight (phr) per 100 weight of elastomer to the solvent volume expressed in ml: greater than 0.3 phr / ml of solvent or less than 0.2 phr / ml of solvent if the process is carried out in air, The process according to claim 1, characterized in that the concentration of the solvent is greater than 0.06 phr / ml when the process is carried out under an inert atmosphere.

3. 3. The method according to claim 1 or 2, wherein the solvent is an organic solvent or an ionic liquid or a deep eutectic solvent or a mixture thereof.

4. 4. The process according to claim 1, wherein the heating time of the mixture is between 2 hours and 4 hours when the process is carried out under an inert atmosphere.

5. The process according to any one of claims 1 to 3, wherein the heating time of the mixture is between 3 hours and 5 hours when the process is carried out in air.

6. 6. The method according to claim 1, further comprising, prior to step a), a step of activating the elastomer-containing waste material by freeze-drying or by swelling.

7. 7. The method of claim 6, wherein the desulfurization reaction and the step of activating the elastomer-containing waste material are carried out continuously.

8. 8. The method according to claim 1, wherein the synthesis of the polymer by devulcanisation is carried out from waste lorry tyres.

9. The method according to any one of claims 1 to 8, wherein the polymer synthesized is represented by the following formula 3 or formula 3': (In the above formula, x is an integer of 0 to 6, n is an integer of 6 to 600, m is an integer of 6 to 600, Y is a hydrogen atom or a methyl group, and R and R′ are the same or different for each unit and are halogen atoms selected from iodine, bromine, fluorine and chlorine; １ -C １８ ) alkyl group, -NH ２ a primary amine represented by the formula: １ (wherein Ra is a secondary amine represented by １ (C １ -C ５ ) an alkyl group and an aromatic ring, -NRa １ Ra ２ (wherein Ra is a tertiary amine represented by １ and Ra ２ are the same or different, each independently of the other (C １ -C ５ ) an alkyl group or an aromatic ring; １ -O － or a salt thereof (wherein Ra １ (C １ -C ５ ) an alkyl group and an aromatic ring, １ -C ５ ) an alkoxy group, a thiol represented by -SH, -SRa １ (wherein Ra is a thioether represented by the formula １ (C １ -C ５ ) an alkyl group and an aromatic ring, Ra １ -S － or a salt thereof (wherein Ra １ (C １ -C ５ ) an alkyl group and an aromatic ring, an aromatic ring, —COO － A conjugate base of a carboxylic acid represented by -COOH, a carboxyl group represented by -CO ２ Ra １ (wherein Ra is an ester represented by the formula: １ (C １ -C ５ ) an alkyl group and a heterocycle; an aldehyde group represented by -CHO; a carbonyl group represented by -COR; ２ a nitro group represented by -CN, a nitrile group represented by -SO ２ a sulfonyl group represented by -, -SO ３ a sulfonate group represented by the formula: ２ Sulfone represented by R, -O-PO(ORa １ ) (ORa ２ ) (wherein Ra １ and Ra ２ are the same or different, and each is independently hydrogen or (C １ -C ５ ) an alkyl group or an aromatic ring, -CONH ２ a primary amide group represented by the formula: １ (wherein Ra is a secondary amide group represented by １ (C １ -C ５ ) an alkyl group and an aromatic ring, or -CONRa １ Ra ２ A tertiary amide group represented by the formula: １ and Ra ２ may be the same or different, each independently of the other (C １ -C ５ ) an alkyl group or an aromatic ring).

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