Grafted elastomer having monoalkoxysilane functions

Abstract

The invention relates to a modified elastomer obtained by grafting at least one compound of formula (I) onto at least one unsaturated site of a starting elastomer (I), in which: - A is a C6-C14 arenediyl ring, optionally substituted with one or more hydrocarbon chains, which may be identical or different, aliphatic, preferably saturated, linear or branched; - E is a C2-C12 divalent hydrocarbon group optionally comprising one or more heteroatoms; and - Ra, Rb, Rc, which may be identical or different, represent a C1-C6 alkyl. The invention also relates to a method for preparing such a modified elastomer and to compositions based on at least one modified elastomer and an additive.

Description

[0001] ELASTOMER GRAFTED WITH MONOALCOXYSILANE FUNCTIONS

[0002] FIELD OF INVENTION

[0003] The field of the present invention is that of elastomers modified by modifying agents; in particular that of diene elastomers modified post-polymerization by 1,3-dipolar compounds.

[0004] STATE OF THE ART

[0005] Elastomeric compositions intended for tire manufacturing include unsaturated elastomers, particularly diene elastomers, and reinforcing fillers that impart good reinforcing properties to the elastomeric compositions containing them. Furthermore, the reinforcing fillers influence the hysteresis properties of the elastomeric compositions.

[0006] Ideally, a tire tread should meet a large number of technical requirements, including low hysteresis, while offering the tire very good road handling.

[0007] This level of road behavior can be achieved by using, in the tread, a judiciously chosen elastomeric composition due to its rather high curing rigidity.

[0008] To increase the curing stiffness of an elastomeric composition, it is known, for example, to increase the rate of reinforcing fillers or to reduce the rate of plasticizers in the elastomeric composition or to introduce styrene and butadiene copolymers with a high styrene content.

[0009] However, some of these solutions generally have the drawback of increasing the hysteresis of the elastomeric composition. Conversely, tire manufacturers need elastomeric compositions with low hysteresis to limit vehicle rolling resistance and fuel consumption. Therefore, improving the stiffness properties of the elastomeric composition must not come at the expense of its hysteresis properties.

[0010] It is also known that increased rigidity results in a decrease in the tensile strength of elastomeric compounds. If tensile strength decreases, the tire will be less resistant to physical stresses, thus exhibiting reduced durability and ultimately a shorter lifespan. Furthermore, given the depletion of raw materials and fossil fuels, it is becoming increasingly important for manufacturers to offer tires with a certain longevity, and therefore good durability.

[0011] It is therefore a permanent objective of designers of elastomeric compositions to ensure that the improvement of certain properties does not come at the expense of others, in particular that obtaining a reinforced elastomeric composition with high stiffness also exhibits good stress-at-break properties and is low hysteretic.

[0012] It is known that, generally speaking, to obtain the optimal reinforcing properties conferred by a reinforcing filler, the latter must be present in the elastomeric matrix in a final form that is both as finely divided as possible and as homogeneously distributed as possible. However, such conditions can only be achieved if the reinforcing filler has a very good ability, firstly, to incorporate into the elastomeric matrix during mixing with the elastomer and to deagglomerate, and secondly, to disperse homogeneously within this matrix.

[0013] Carbon black is known to possess such properties, which is generally not the case for inorganic reinforcing fillers like silica. Indeed, due to mutual affinities, inorganic reinforcing filler particles tend to agglomerate within the elastomeric matrix. These interactions limit the dispersion of the inorganic reinforcing filler and thus restrict its reinforcing properties to a level significantly lower than that which could theoretically be achieved if all the bonds (reinforcing fillers / elastomers) that could be formed during the mixing process had actually been established.

[0014] Many solutions have already been tested to achieve good dispersion of the reinforcing inorganic filler in an elastomeric composition and to obtain elastomeric compositions exhibiting a decrease in hysteresis.

[0015] In particular, it is common practice to use polysulfide silane compounds, known as coupling agents for the inorganic reinforcing filler to the elastomer, to improve the dispersion of this reinforcing inorganic filler. However, these coupling agents are manufactured from fossil-based raw materials and are expensive to produce. Given the environmental impact of using these raw materials, it is becoming a major challenge for tire manufacturers to use as few such coupling agents as possible without diminishing the properties of the elastomeric compositions and / or altering the dispersion of the inorganic reinforcing filler within the composition. Furthermore, it is always advantageous for a manufacturer to reduce the production costs of these compositions.

[0016] In order to improve the dispersion of the reinforcing filler, especially the inorganic reinforcing filler, it is also known to use elastomers, especially diene elastomers, modified by post-polymerization grafting using modifying or functionalizing agents.

[0017] For example, document W02020 / 094993 describes a grafting agent that is a 1,3-dipolar compound containing an imidazole functional group. This nitrile oxide, 2,4,6-trimethyl-3((2-methyl-1H-imidazol-lyl)methyl)benzene, when grafted to the ethylene-butadiene copolymer elastomer, imparts good properties to compositions reinforced with an inorganic reinforcing filler, as demonstrated by strain measurements. However, the compositions in this document contain a coupling agent for the inorganic reinforcing filler to the elastomer.

[0018] There is, therefore, always a constant need for new elastomers, in particular diene elastomers, modified by post-polymerization grafting which allow access to elastomeric compositions with a good compromise of properties such as stiffness, hysteresis and tensile strength, while maintaining good dispersion of the inorganic reinforcing filler in these compositions.

[0019] DESCRIPTION OF THE INVENTION

[0020] The applicant has thus developed new elastomers, in particular new diene elastomers, grafted with monoalkoxysilane pendant groups, which make it possible to meet the needs mentioned above.

[0021] Thus, a first object of the present invention relates to a modified elastomer obtained by grafting at least one compound of formula (I) onto at least one unsaturation of an initial elastomer

[0022] (I) in which:

[0023] A represents an arenediyl ring in CÔ-CU, possibly substituted by one or more hydrocarbon chains, identical or different, aliphatic, preferably saturated, linear or branched;

[0024] E represents a divalent hydrocarbon group in the C2-C12 range, possibly comprising one or more heteroatoms; and

[0025] Ra, Rb, Rc, whether identical or different, represent an alkyl in C1-CO.

[0026] Surprisingly, the modified elastomers, particularly the diene elastomers, of the invention described above allow for the production of elastomeric compositions exhibiting a good compromise between stiffness, hysteresis, and tensile strength, while maintaining good dispersion of the inorganic reinforcing filler. Also surprisingly, they allow for the production of these compositions using little or no polysulfide silane coupling agents. Advantageously, this results in a lower manufacturing cost for these elastomeric compositions.

[0027] Another object of the present invention is a composition based on at least one additive and at least one elastomer, in particular a modified diene elastomer obtained by grafting at least one compound of formula (I) as described above onto at least one unsaturation of an initial elastomer. Another object of the present invention is a process for preparing a modified elastomer, said process comprising a step of grafting a compound of formula (I) onto an initial elastomer comprising at least one unsaturation by cycloaddition [3+2] of the nitrile oxide of the compound of formula (I) onto said unsaturation.

[0028] (I) in which:

[0029] A represents an arenediyl ring in CÔ-CU, possibly substituted by one or more hydrocarbon chains, identical or different, aliphatic, preferably saturated, linear or branched;

[0030] E represents a divalent hydrocarbon group in the C2-C12 range, possibly comprising one or more heteroatoms; and

[0031] Ra, Rb, Rc, whether identical or different, represent an alkyl in C1-CO.

[0032] DETAILED DESCRIPTION OF THE INVENTION

[0033] As mentioned above, a first object of the present invention relates to a modified elastomer obtained by grafting at least one compound of formula (I) onto at least one unsaturation of an initial elastomer

[0034] (I) in which:

[0035] A represents an arenediyl ring in CÔ-CU, possibly substituted by one or more hydrocarbon chains, identical or different, aliphatic, preferably saturated, linear or branched;

[0036] E represents a divalent hydrocarbon group in the C2-C12 range, possibly comprising one or more heteroatoms; and

[0037] Ra, Rb, Rc, whether identical or different, represent an alkyl in C1-CO.

[0038] In this document, unless expressly stated otherwise, all percentages (%) shown are percentages (%) by mass. On the other hand, any range of values ​​designated by the expression "between a and b" represents the range of values ​​from greater than a to less than b (i.e., excluding bounds a and b), while any range of values ​​designated by the expression "from a to b" means the range of values ​​from a to b (i.e., including the strict bounds a and b).

[0039] The compounds mentioned in the description can be of fossil origin or bio-based. In the latter case, they may be partially or entirely derived from biomass or obtained from renewable raw materials derived from biomass. Obviously, the compounds mentioned can also come from the recycling of previously used materials; that is, they may be partially or entirely produced through a recycling process, or obtained from raw materials themselves derived from a recycling process. This includes, in particular, polymers, plasticizers, fillers, etc.

[0040] The expression "composition based on" means a composition comprising the mixture and / or the in situ reaction product of the different constituents used, some of these constituents being able to react and / or being intended to react with each other, at least partially, during the different phases of manufacturing the composition; the composition can thus be in a totally or partially crosslinked state or in a non-crosslinked state.

[0041] The expression "part by weight per hundred parts by weight of elastomer" (or pce) is to be understood in the context of the present invention as the part, by mass per hundred parts by mass of elastomer.

[0042] The term 1,3-dipolar compound is understood according to the definition given by IUP AC. By definition, a 1,3-dipolar compound includes a dipole.

[0043] For the purposes of this invention, "hydrocarbon chain" means a chain comprising one or more carbon atoms and one or more hydrogen atoms.

[0044] The expression "Ci-Cj alkyl" refers to a linear, branched or cyclic hydrocarbon group comprising i to j carbon atoms; i and j being integers.

[0045] The expression "Ci-Cj aryl" refers to an aromatic group containing i to j carbon atoms; i and j being integers.

[0046] An "alkanediyl" is a hydrocarbon group derived from an alkane in which two hydrogen atoms have been removed. An alkanediyl is therefore a divalent group.

[0047] The invention and its advantages will be readily understood in light of the description and implementation examples that follow.

[0048] The term "grafted modified elastomer" or "grafted modified elastomer" refers to an elastomer containing functional groups, particularly monoalkoxysilane groups, that have been introduced into the F elastomer chain. In practice, a modified F elastomer is obtained by grafting a compound bearing a monoalkoxysilane group and a functional group capable of forming a covalent bond with an unsaturation of the F elastomer. This covalently bonding functional group is a nitrile oxide. The grafting reaction is therefore the covalent attachment of the compound of formula (I) bearing a monoalkoxysilane group to at least one unsaturation of the elastomer chain.

[0049] As is known, an elastomer generally comprises at least one main elastomer chain. This elastomer chain can be considered main when all other chains of the elastomer are considered to be pendant chains, as mentioned in the document "Glossary of basic terms in polymer science" (IUPAC recommendations 1996), PAC, 1996, 68, 2287, p2294.

[0050] By "unsaturation" we mean a multiple covalent bond between two carbon atoms; this multiple covalent bond can be a carbon-carbon double bond or a carbon-carbon triple bond, preferably a carbon-carbon double bond.

[0051] For the purposes of this invention, the term "initial elastomer chain" refers to the elastomer chain prior to the grafting reaction; this chain comprises at least one unsaturation capable of reacting with the compound of formula (I) described above. The initial elastomer is therefore the elastomer used as the starting reagent in the grafting reaction. The grafting reaction allows a modified elastomer to be obtained from an initial elastomer.

[0052] Preferably, the initial elastomer can be a diene elastomer.

[0053] By "diene" elastomer (or indistinctly rubber), whether natural or synthetic, should be understood in a known way as an elastomer consisting at least in part (i.e., a homopolymer or a copolymer) of diene monomer units (monomers bearing two carbon-carbon double bonds, conjugated or not).

[0054] The term diene elastomer suitable for use in the context of the present invention means in particular: any homopolymer of a diene monomer, conjugated or not, having from 4 to 18 carbon atoms; any copolymer of a diene monomer, conjugated or not, having from 4 to 18 carbon atoms and at least one other monomer.

[0055] The other monomer can be ethylene, an olefin or a diene, conjugated or not.

[0056] Suitable conjugated dienes are those with 4 to 12 carbon atoms, in particular 1,3-dienes, such as 1,3-butadiene and isoprene.

[0057] Suitable as unconjugated dienes are unconjugated dienes having 6 to 12 carbon atoms, such as 1,4-hexadiene, ethylidene norbornene, dicyclopentadiene.

[0058] Suitable olefins include vinylaromatic compounds with 8 to 20 carbon atoms and aliphatic α-monoolephs with 3 to 12 carbon atoms.

[0059] Suitable examples of vinylaromatic compounds include styrene, ortho-, meta-, para-methylstyrene, the commercial vinyl-toluene mixture, and para-tert-butylstyrene. Suitable examples of aliphatic α-monoolefins include acyclic aliphatic α-monoolefins with 3 to 18 carbon atoms.

[0060] More specifically, a diene elastomer can be: any homopolymer of a conjugated diene monomer, in particular any homopolymer obtained by polymerization of a conjugated diene monomer having 4 to 12 carbon atoms; any copolymer obtained by copolymerization of one or more dienes conjugated to each other or with one or more vinylaromatic compounds having 8 to 20 carbon atoms; a copolymer of isobutene and isoprene (butyl rubber), as well as halogenated versions, in particular chlorinated or brominated, of this type of copolymer; any copolymer obtained by copolymerization of one or more dienes, conjugated or not, with ethylene, an α-monoolefin or their mixture such as for example elastomers obtained from ethylene, propylene with a non-conjugated diene monomer of the aforementioned type.

[0061] The diene elastomer may be selected from homopolymers of a diene monomer, conjugated or not, having from 4 to 12 carbon atoms, copolymers of a diene monomer, conjugated or not, having from 4 to 12 carbon atoms and at least one other monomer selected from the group consisting of (i) ethylene, (ii) vinylaromatic compounds having from 8 to 20 carbon atoms, (iii) aliphatic alpha-monoolefins having from 3 to 12 carbon atoms and (iv) diene monomer, conjugated or not, having from 4 to 18 carbon atoms, and mixtures of these homopolymers and copolymers.

[0062] Preferably, the diene elastomer may be selected from homopolymers of 1,3-diene monomers, copolymers of 1,3-diene monomers and at least one other monomer selected from the group consisting of ethylene, styrene, propylene and 1,3-diene monomers and mixtures of these homopolymers and copolymers.

[0063] Preferably, the 1,3-diene monomer is chosen from 1,3-butadiene, 2-methyl-1,3-butadiene (or isoprene) units, units of the formula CH2=CR-CH=CH2, the symbol R representing a hydrocarbon chain having 3 to 20 atoms as described below, and mixtures thereof. More preferably still, the 1,3-diene monomer is 1,3-butadiene, isoprene, and mixtures thereof.

[0064] More preferably, the diene elastomer may be selected from homopolymers of 1,3-diene monomers, copolymers of 1,3-diene monomers and at least one other monomer selected from the group consisting of ethylene, styrene, propylene, and 1,3-diene monomers, and mixtures of these homopolymers and copolymers; the 1,3-diene monomer may be selected from 1,3-butadiene, isoprene, and mixtures thereof. When the initial elastomer is preferably a homopolymer of 1,3-diene monomer, it may be selected from the group consisting of natural rubber (NR), synthetic polyisoprene (IR), polybutadiene (BR), and mixtures of these elastomers.

[0065] When the initial elastomer is preferably a copolymer, it can be chosen from the group consisting of ethylene-propylene-1,3-diene monomer (EPDM) copolymers, ethylene-1,3-diene monomer copolymers, styrene-1,3-diene monomer copolymers, copolymers of 1,3-diene monomers different from each other, and mixtures of these elastomers.

[0066] Examples of copolymers resulting from the polymerization of different 1,3-diene monomers that can be used as an initial elastomer in the context of the present invention include isoprene and butadiene copolymers (BIR).

[0067] Examples of copolymers resulting from the polymerization of a styrene monomer and 1,3-diene monomers usable as an initial elastomer in the context of the present invention include styrene-butadiene copolymers (SBR), styrene-isoprene copolymers (SIR), styrene-isoprene-butadiene copolymers (SBIR), and mixtures of these elastomers.

[0068] Among the copolymers resulting from the polymerization of a 1,3-diene monomer with another monomer chosen from the group consisting of ethylene, styrene, propylene, 1,3-diene monomers, copolymers containing ethylene units and 1,3-diene units are particularly preferred.

[0069] The term "copolymer containing ethylene and 1,3-diene units," or "ethylene-1,3-diene copolymer," or "ethylene monomer-1,3-diene monomer copolymer," refers to any copolymer comprising, within its structure, at least ethylene units and 1,3-diene units. This copolymer may comprise a single type of 1,3-diene monomer or several 1,3-diene monomers of different chemical natures.

[0070] The copolymer may also include monomer units other than ethylene and 1,3-diene units, but this is not preferred. For example, the copolymer may also include alpha-olefin units, particularly alpha-olefin units having from 3 to 18 carbon atoms, advantageously having from 3 to 6 carbon atoms. For example, the alpha-olefin units may be selected from the group consisting of propylene, butene, pentene, hexene, or mixtures thereof.

[0071] The well-known expression "ethylene unit" refers to the -(CH2-CH2)- motif resulting from the insertion of ethylene into the copolymer chain.

[0072] The term "1,3-diene unit" is known to refer to units resulting from the insertion of the 1,3-diene monomer by a 1,4 addition, a 1,2 addition, or a 3,4 addition in the case of a substituted diene such as isoprene, for example.

[0073] Preferably, the 1,3-diene units may be 1,3-diene units having 4 to 24 carbon atoms, more preferably the 1,3-diene units may be chosen from the group consisting of 1,3-butadiene units, 2-methyl-1,3-butadiene (or isoprene) units, units of formula CH2=CR-CH=CH2, the symbol R representing a hydrocarbon chain having 3 to 20 carbon atoms and mixtures of these units.

[0074] Advantageously, the ethylene units represent 50% to 95% by mole of the total number of moles of monomer units in the copolymer. Most preferably, the copolymer contains ethylene units representing 70% to 85% by mole of the total number of moles of monomer units in the copolymer.

[0075] When the ethylene and 1,3-diene unit copolymer is a copolymer containing ethylene units and units of a 1,3-diene of formula CH2=CR-CH=CH2, the symbol R representing a hydrocarbon chain having 3 to 20 carbon atoms, then the ethylene units in the copolymer can represent between 50% and 95% by mole relative to the total number of moles.

[0076] The 1,3-diene with the formula CH2=CR-CH=CH2 is a substituted 1,3-diene, which can give rise to units of configuration 1,2 represented by formula (1), of configuration 3,4 represented by formula (2) and of configuration 1,4 whose trans form is represented below by formula (3)

[0077] In the formula CH2=CR-CH=CH2 for the 1,3-diene unit, the hydrocarbon chain represented by the symbol R can be a saturated or unsaturated chain of 3 to 20 carbon atoms, preferably having 6 to 16 carbon atoms. It can be a linear, branched, or acyclic chain. Preferably, the hydrocarbon chain represented by the symbol R is advantageously an unsaturated, branched, acyclic chain containing 3 to 20 carbon atoms, particularly 6 to 16 carbon atoms. Very advantageously, this 1,3-diene unit can be chosen from the group consisting of myrcene, p-famesene, and mixtures of myrcene and p-famesene. Even more advantageously, this 1,3-diene unit is myrcene.

[0078] Advantageously, when the copolymer contains units of 1,3-diene of formula CH2=CR-CH=CH2 as described above, these can represent between 10% and 40% by mole, preferably between 15% and 30% by mole, relative to the total number of moles of monomer units in the copolymer.

[0079] The copolymer containing ethylene units and units of a 1,3-diene of the formula CH2=CR-CH=CH2 as described above may include a second 1,3-diene unit selected from 1,3-butadiene, isoprene, or a mixture thereof. In this case, the copolymer is a copolymer of ethylene, a 1,3-diene of the formula CH2=CR-CH=CH2 as described above, and a second 1,3-diene unit selected from 1,3-butadiene, isoprene, or a mixture thereof. Advantageously, the second 1,3-diene unit of the copolymer is 1,3-butadiene.

[0080] When the copolymer containing ethylene units and units of a 1,3-diene of formula CH2=CR-CH=CH2 as described above contains units of the second 1,3-diene, these may advantageously represent between 1% and 49% by moles, preferably between 4% and 29% by moles, preferably between 4% and 25% by moles relative to the total number of moles of monomer units of the copolymer.

[0081] When the 1,3-diene unit is 1,3-butadiene, the copolymer may also contain 1,2-cyclohexanediyl repeating units. The presence of these cyclic structures in the copolymer results from a very specific insertion of ethylene and 1,3-butadiene during polymerization. The content of 1,2-cyclohexanediyl repeating units in the copolymer varies depending on the respective contents of ethylene and 1,3-butadiene in the copolymer. Preferably, the copolymer contains less than 15 mole percent of 1,2-cyclohexanediyl repeating units relative to the total number of moles of monomer units in the copolymer.

[0082] A copolymer containing ethylene units and 1,3-diene units, particularly useful in the context of the present invention, may be a copolymer containing ethylene units and 1,3-butadiene units. More preferably, in this copolymer containing ethylene units and 1,3-butadiene units, the ethylene units represent from 50% to 95% by mole relative to the total number of moles of monomer units in the copolymer. Most preferably, this copolymer contains ethylene units that represent from 70% to 85% by mole relative to the total number of moles of monomer units in the copolymer.

[0083] The copolymer of ethylene and a 1,3-diene (preferably 1,3-butadiene) can be obtained by various synthetic methods known to those skilled in the art, particularly depending on the desired microstructure of the copolymer. Generally, it can be prepared by copolymerization of at least one 1,3-diene as described above and ethylene, using known synthetic methods, especially in the presence of a catalytic system described in documents EP1092731A1, W02004035639A1, W02007054223A2, W02007054224A2, WO2017093654A1, WO 2018020122A1, WO 2018020123A1 and W02020070443A1.

[0084] The initial elastomers usable within the scope of the invention, preferably diene elastomers, can have any microstructure that depends on the polymerization conditions used. These elastomers can, for example, be block, random, sequenced, or microsequenced, and be prepared as dispersions, emulsions, or solutions. They can be coupled and / or star-shaped, for example, by means of a silicon or tin atom that links the elastomer chains together.

[0085] According to the invention, the initial elastomer, preferably the diene elastomer, is modified by grafting a compound of formula (I) as defined above, also called a modifying agent.

[0086] According to formula (I), the compound according to the invention comprises group A which represents a CÔ-CU arenediyl ring, optionally substituted by one or more identical or different aliphatic hydrocarbon chains, preferably saturated, linear or branched.

[0087] For the purposes of this invention, an "arendiyl ring" is defined as a monocyclic or polycyclic aromatic hydrocarbon group derived from an arene in which two hydrogen atoms have been removed. An arendiyl ring is therefore a divalent group.

[0088] A monocyclic or polycyclic aromatic hydrocarbon group is defined as one or more aromatic rings whose backbone is composed of carbon atoms. In other words, there are no heteroatoms in the ring's backbone. The arenediyl ring can be monocyclic, meaning it consists of a single ring, or polycyclic, meaning it consists of several condensed aromatic hydrocarbon rings; such condensed rings then share at least two successive carbon atoms. These rings can be orthocondensed or ortho- and pericondensed. The arenediyl ring comprises from 6 to 14 carbon atoms.

[0089] The arenediyl ring can be unsubstituted, partially substituted, or totally substituted. An arenediyl ring is partially substituted when one, two, or more hydrogen atoms (but not all) are replaced by one, two, or more aliphatic hydrocarbon chains, preferably saturated, linear or branched. These chains are also called substituents. If all the hydrogen atoms are replaced by these chains, then the arenediyl ring is totally substituted. The substituents of the arenediyl ring can be identical or different from one another.

[0090] Preferably, when the arenediyl ring is substituted by one or more hydrocarbon chain(s), identical or different, independent of each other, this or these chain(s) are inert with respect to the substituted silicon atom and the nitrile oxide group.

[0091] For the purposes of this invention, "inert hydrocarbon chain(s) with respect to the substituted silicon atom and the nitrile oxide group" means a hydrocarbon chain that does not react with either the substituted silicon atom or the nitrile oxide group. Thus, the inert hydrocarbon chain with respect to the substituted silicon atom and the nitrile oxide group is, for example, a hydrocarbon chain that does not contain alkenyl or alkynyl functional groups capable of reacting with the substituted silicon atom or the nitrile oxide group. Preferably, these hydrocarbon chains are aliphatic, saturated, linear or branched, and may comprise from 1 to 24 carbon atoms.

[0092] Preferably, A represents a CÔ-CU arendiyl ring, optionally substituted by one or more identical or different hydrocarbon chain(s), saturated at C1-C24. More preferably still, group A is a CÔ-CU arendiyl ring, optionally substituted by one or more substituents, identical or different, the substituents being alkyls at C1-C12, preferably at CI-CÔ, more preferably at C1-C4.

[0093] In compounds of formula (I), E represents a C2-C12 hydrocarbon divalent group that may optionally contain one or more heteroatoms. For the purposes of this invention, "hydrocarbon divalent group" means a spacer group (or bonding group) forming a bridge between the oxygen atom attached to A and the silicon atom substituted by Ra, Rb, or -ORc, with Ra, Rb, and Rc as defined above; this spacer group E comprising from 2 to 12 carbon atoms. This spacer group may be a C2-C12 hydrocarbon chain, preferably saturated, linear or branched, that may optionally contain one or more heteroatoms such as, for example, N, O, and S. This hydrocarbon chain may optionally be substituted, provided that the substituents do not react with the T group and the substituted silicon atom as defined above.

[0094] Preferably, in compounds of formula (I), E can represent a divalent hydrocarbon group in C2-C10, preferably in C2-C9, more preferably in C2-C7, more preferably still in C2-C5, possibly containing one or more heteroatom(s) such as, for example, N, O and S.

[0095] More preferably, in compounds of formula (I), E can represent a C2-C10 alkanediyl, preferably a C2-C9 alkanediyl, more preferably a C2-C7 alkanediyl, and even more preferably a C2-C5 alkanediyl.

[0096] Preferably, in compounds of formula (I), Ra, Rb, Rc, identical or different, can be a C1-C4 alkyl, preferably a C1-C4 alkyl.

[0097] Preferably, in compounds of formula (I), Ra and Rb may be identical and may be a C1-C4 alkyl, preferably the methyl, and Rc may be the ethyl.

[0098] Preferably, in compounds of formula (I), Ra, Rb, Rc, identical or different, can be methyl or ethyl.

[0099] According to a preferred embodiment of the invention, in the compounds of formula (I), Ra and Rb can be methyl and Rc can be ethyl.

[0100] Preferably, the compound of formula (I) can be chosen from among the compounds of formula (la) and the compounds of formula (lia) in which (i) a grouping chosen from Ri to R5 of formula (la) and a grouping chosen from Ri to R7 of formula (lia) denote the following group of formula (II): in which E, Ra, Rb, Rc are as defined above and the symbol (*) represents attachment to (la) or to (Ha), and (ii) the four groups of formula (la) chosen from Ri to Rs other than that designating the group of formula (II) and the six groups of formula (lia) chosen from Ri to Rs other than that designating the group of formula (II), identical or different, independently represent a hydrogen atom or an aliphatic hydrocarbon chain, preferably saturated, linear or branched in C1-C24, and preferably independently represent a hydrogen atom or an alkyl in C1-C12.

[0101] Preferably, in the compounds of formulas (la) and (lia), the four groups of formula (la) chosen from Ri to R5 other than that designating the group of formula (II) and the six groups of formula (lia) chosen from Ri to R7 other than that designating the group of formula (II), identical or different, represent independently of each other, a hydrogen atom or an aliphatic hydrocarbon chain, saturated, linear or branched, in C1-C24.

[0102] Even more preferably, in the compounds of formulas (la) and (lia), the four groups of formula (la) chosen from Ri to R5 other than that designating the group of formula (II) and the six groups of formula (lia) chosen from Ri to R7 other than that designating the group of formula (II), identical or different, are chosen from the group consisting of the hydrogen atom, the alkyls in C1-C12, preferably in C1-C2, even more preferably in C1-C4.

[0103] More preferably still, in the compounds of formulas (la) and (lia), the four groups of formula (la) chosen from Ri to R5 other than that designating the group of formula (II) and the six groups of formula (lia) chosen from Ri to R7 other than that designating the group of formula (II), identical or different, represent independently of each other, a hydrogen atom or a methyl.

[0104] According to a preferred embodiment of the invention, in formula (la), R2 represents a group of formula (II) and Ri, R3, R4 and R5, identical or different, represent a hydrogen atom or an aliphatic hydrocarbon chain, preferably saturated, linear or branched, in C1-C24. More preferably, R2 represents a group of formula (II) and Ri, R3, R4 and R5, identical or different, are chosen from the group consisting of a hydrogen atom and an alkyl in C1-C12, more preferably in C1-C2, more preferably in C1-C4.

[0105] More preferably in this embodiment, R2 represents a group of formula (II), R4 represents a hydrogen atom, and Ri, R3, and R5 represent an aliphatic hydrocarbon chain, preferably saturated, linear or branched, in C1-C24. More preferably still, R2 represents a group of formula (II), R4 represents a hydrogen atom, and Ri, R3, and R5, identical or different, represent an alkyl group in C1-C12, more preferably in C1-C2, more preferably in C1-C4.

[0106] According to another preferred embodiment of the invention, in formula (Ha), Ri represents a group of formula (II) and R2 to R7, identical or different, represent a hydrogen atom or an aliphatic hydrocarbon chain, preferably saturated, linear or branched, in C1-C24. More preferably, Ri represents a group of formula (II) and R2 to R7, identical or different, are chosen from the group consisting of a hydrogen atom and an alkyl group in C1-C12, more preferably in C1-C2, more preferably in C1-C4. Even more preferably in this embodiment, Ri represents a group of formula (II) and R2 to R7, identical, represent a hydrogen atom.

[0107] Preferably, in compounds of formula (la), and (Ila), E represents a divalent hydrocarbon group in C2-C10, preferably in C2-C9, more preferably in C2-C7, more preferably still in C2-C5, possibly containing one or more heteroatom(s) such as, for example, N, O and S.

[0108] More preferably, in the compounds of formula (la), and (Ila), E represents a C2-C10 alkanediyl, preferably a C2-C9 alkanediyl, more preferably a C2-C7 alkanediyl, and even more preferably a C2-C5 alkanediyl.

[0109] Preferably, in compounds of formula (la) and (lia), Ra, Rb, Rc, identical or different, are a C1-C4 alkyl, preferably a C1-C4 alkyl.

[0110] Preferably, in compounds of formula (la) and (Ha), Ra and Rb are identical and are a C1-C4 alkyl, preferably the methyl, and Rc is the ethyl.

[0111] Preferably, in compounds of formula (la) and (lia), Ra, Rb, Rc, whether identical or different, are methyl or ethyl.

[0112] According to a preferred embodiment of the invention, in the compounds of formula (la) and (Ha), Ra and Rb are methyl and Rc is ethyl.

[0113] Preferably, the compound of formula (I) may be the compound of formula (la) in which the group R2 is the group of formula (II) with the group E representing a C2-C9 alkanediyl, more preferably a C2-C7 alkanediyl, more preferably a C2-C5 alkanediyl, the groups Ra, Rb, Rc identical or different, are a C1-C4 alkyl, preferably a C1-C4 alkyl, more preferably are chosen from the methyl and ethyl groups, the group R4 represents a hydrogen atom and the groups Ri, R3, R5 identical or different, represent a C1-C4 alkyl, preferably a C1-C4 alkyl, more preferably the methyl group.

[0114] A particularly preferred compound of formula (I) is the compound of formula (III):

[0115] Surprisingly, modified elastomers, particularly dienic elastomers, obtained by grafting compounds (I) and its preferred forms (la), (lia), and (III), described above, allow access to elastomeric compositions exhibiting a good compromise of properties such as stiffness, hysteresis, and tensile strength, while maintaining good dispersion of the inorganic reinforcing filler. Also surprisingly, they allow access to compositions using little or no polysulfide-silane coupling agents. Thus, advantageously, the manufacturing cost of these elastomeric compositions is lower.

[0116] The compounds of formula (I) are obtained according to the process described below, which a person skilled in the art will be able to adapt to obtain the preferred modes (la), (lia) and (III).

[0117] The process for preparing a compound of formula (I) may include at least one reaction (d) of a compound of formula (Ib) with a halogenating agent in the presence of at least one organic solvent SL1 according to the following reaction scheme: with :

[0118] A represents a CÔ-CU arenediyl ring, possibly substituted by one or more identical or different aliphatic hydrocarbon chains, preferably saturated, linear or branched; E represents a C2-C12 divalent hydrocarbon group possibly comprising one or more heteroatoms; and

[0119] Ra, Rb, Rc, whether identical or different, represent an alkyl in C1-CO.

[0120] The preferred modes of A, E, Ra, Rb and Rc as described above, also apply to the process of preparing the compound of formula (I) from a compound of formula (Ib).

[0121] Preferably, the halogenating agent is chosen from the group consisting of N-bromosuccinimide in the presence of a base, N-chlorosuccinimide in the presence of a base, and sodium hypochlorite. Preferably, the base may be triethylamine. A halogenating agent is defined as a chemical compound that enables halogenation or dehalogenation reactions to occur via an addition or substitution mechanism.

[0122] Advantageously, the amount of halogenating agent is in the range of 1 to 5 molar equivalents, preferably 1 to 2 molar equivalents relative to the molar amount of the compound of formula (Ib).

[0123] Preferably, the organic solvent SL1 is chosen from chlorinated solvents, ester-type solvents, ether-type solvents and alcohol-type solvents, more preferably chosen from dichloromethane, trichloromethane, ethyl acetate, butyl acetate, diethyl ether, isopropanol and ethanol, even more preferably is chosen from ethyl acetate, trichloromethane, dichloromethane and butyl acetate.

[0124] Preferably, at the start of the reaction, the compound of formula (Ib) represents from 1% to 30% by weight, preferably from 1% to 20% by weight, relative to the total weight of the assembly comprising said compound of formula (Ib), said organic solvent SL1 and said halogenating agent.

[0125] The compound of formula (Ib) can in particular be obtained from a preparation process comprising at least one reaction (c) of at least one compound of formula (le) with an aqueous solution of hydroxylamine NH2OH (compound of formula (IV)) according to the following reaction scheme:

[0126] with :

[0127] A represents an arenediyl ring in CÔ-CU, possibly substituted by one or more hydrocarbon chains, identical or different, aliphatic, preferably saturated, linear or branched;

[0128] E represents a divalent hydrocarbon group in the C2-C12 range, possibly comprising one or more heteroatoms; and

[0129] Ra, Rb, Rc, whether identical or different, represent an alkyl in C1-CO.

[0130] The preferred modes of A, E, Ra, Rb and Rc as described above, also apply to the process of preparing a compound of formula (Ib) from a compound of formula (le).

[0131] Preferably, F hydroxylamine (compound of formula (IV)) can be added to the reaction medium at a temperature within a range of 1°C to 100°C, more preferably within a range of 20°C to 70°C.

[0132] The compound of formula (the) can be obtained by a preparation process comprising at least one hydrosilylation reaction (b) of the compound of formula (V) with a compound of formula (VI), preferably in the presence of an organometallic catalyst, according to the following reaction scheme: with :

[0133] A represents an arenediyl ring in CÔ-CU, possibly substituted by one or more hydrocarbon chains, identical or different, aliphatic, preferably saturated, linear or branched;

[0134] E represents a divalent hydrocarbon group in C2-C12 possibly comprising one or more heteroatoms;

[0135] Ra, Rb, Rc, whether identical or different, represent an alkyl group in the form C1-CO; and

[0136] Ei represents a group -(CH2)n-CH=CH2 with n an integer from 0 to 10, preferably from 0 to 8, more preferably from 0 to 7, more preferably still from 0 to 3.

[0137] The preferred modes of A, E, Ra, Rb and Rc also apply to the process of preparing a compound of formula (the) from the compound of formula (VI) and the compound of formula (V).

[0138] The reaction between the compound of formula (VI) and that of formula (V) can generally be carried out, in particular, in the presence of an organometallic catalyst and preferably at a temperature within a range of 0°C to 150°C, preferably within a range of 20°C to 80°C. The organometallic catalyst may be a platinum-based organometallic complex, such as, in particular, a Karstedt catalyst or a Speier catalyst.

[0139] Preferably, one can introduce into the reaction medium, for example, less than 1000 ppm, preferably less than 500 ppm, of platinum calculated in relation to the total mass of compound (VI) and of the compound of formula (V).

[0140] Compounds of formula (V) as defined above are commercially available from suppliers such as Sigma-Aldrich, Merk, Chimieliva, etc. Compound of formula (VI) can be obtained by nucleophilic substitution of a halogenated compound of formula (VII) by an alcohol compound of formula (VIII) according to the following reaction scheme: with

[0141] A represents an arenediyl ring in CÔ-CU, possibly substituted by one or more hydrocarbon chains, identical or different, aliphatic, preferably saturated, linear or branched;

[0142] Ei represents a group -(CH2)n-CH=CH2 with n an integer from 0 to 10, preferably from 0 to 8, more preferably from 0 to 7, and even more preferably from 0 to 3; and

[0143] X represents a halogen atom chosen from the group consisting of bromine, iodine and chlorine, preferably bromine.

[0144] Preferably, this reaction takes place in the presence of a Brønsted base such as, for example, a tertiary amine of the triethylamine type, or a mineral base of the potassium or sodium carbonate type, or even with potassium or sodium hydroxide. Preferably, this reaction takes place at a temperature in the range of 20°C to 150°C, more preferably in the range of 30°C to 100°C, and even more preferably in the range of 35°C to 70°C.

[0145] The compounds of formula (VIII) and (VII) are commercially available from suppliers such as Sigma Aldrich, ABCR.

[0146] As explained previously, the compounds of formula (I) and their preferred embodiments, in particular the compound of formula (III), are used as functionalizing agents. They can be grafted onto one or more elastomers comprising at least one unsaturated carbon-carbon bond; in particular, this elastomer can be a diene elastomer as defined previously. The compounds of formula (I) and their preferred forms advantageously allow the production of grafted elastomers (also called modified elastomers), particularly grafted diene elastomers, regardless of the initial microstructure of the elastomer, the only requirement being that the elastomer comprises at least one unsaturated carbon-carbon bond, preferably a carbon-carbon double bond.Surprisingly, modified elastomers, particularly dienic elastomers, obtained by grafting compounds (I) and its preferred forms (la), (lia), and (III), described above, allow access to elastomeric compositions exhibiting a good compromise of properties such as stiffness, hysteresis, and tensile strength, while maintaining good dispersion of the inorganic reinforcing filler. Also surprisingly, they allow access to compositions using little or no polysulfide-silane coupling agents. Thus, advantageously, the manufacturing cost of these elastomeric compositions is lower.

[0147] The invention also relates to a method for preparing a modified elastomer, said method comprising a step of grafting a compound of formula (I) onto an initial elastomer comprising at least one unsaturation by cycloaddition [3+2] of the nitrile oxide of the compound of formula (I) onto said unsaturation in which:

[0148] A represents an arenediyl ring in CÔ-CU, possibly substituted by one or more hydrocarbon chains, identical or different, aliphatic, preferably saturated, linear or branched;

[0149] E represents a divalent hydrocarbon group in the C2-C12 range, possibly comprising one or more heteroatoms; and

[0150] Ra, Rb, Rc, whether identical or different, represent an alkyl in C1-CO.

[0151] Preferably, the process for preparing a modified elastomer may include a step of grafting a compound of formula (la) or (lia), more preferably a compound of formula (III), onto an initial elastomer comprising at least one unsaturation by cycloaddition [3+2] of nitrile oxide of said compound onto said unsaturation. Preferably, the initial elastomer F may be a diene elastomer as defined above.

[0152] Preferably, this elastomer can be selected from homopolymers of a diene monomer, conjugated or not, having from 4 to 12 carbon atoms, copolymers of a diene monomer, conjugated or not, having from 4 to 12 carbon atoms and at least one other monomer selected from the group consisting of ethylene, vinylaromatic compounds having from 8 to 20 carbon atoms and aliphatic alpha-monoolefins having from 3 to 12 carbon atoms, diene monomer conjugated or not, having from 4 to 18 carbon atoms, and mixtures of these homopolymers and copolymers. More preferably, this diene elastomer can be chosen from homopolymers of 1,3-diene monomers, copolymers of 1,3-diene monomers and at least one other monomer chosen from the group consisting of ethylene, styrene, propylene, 1,3-diene monomers and mixtures of these homopolymers and copolymers.Preferably, the 1,3-diene monomer is chosen from the group consisting of 1,3-butadiene and isoprene.

[0153] More specifically, the initial elastomer may be a copolymer containing ethylene units and 1,3-diene units, or more preferably, a copolymer containing ethylene units and 1,3-butadiene units. Most preferably, in this copolymer containing ethylene units and 1,3-butadiene units, the ethylene units represent 50% to 95% by mole relative to the total number of moles of monomer units in the copolymer. Very preferably, this copolymer contains ethylene units that represent 70% to 85% by mole relative to the total number of moles of monomer units in the copolymer.

[0154] The grafting of these compounds is carried out by [3+2] cycloaddition of the nitrile oxide group of said compounds onto an unsaturated carbon-carbon bond of the elastomer chain. The mechanism of this cycloaddition is illustrated in particular in document WO2012 / 007441 Al, specifically on page 13. During this reaction, said compound of formula (I) and its preferred embodiments, in particular the compound of formulas (la), (lia), and (III), form covalent bonds with the elastomer chain.

[0155] According to the invention, the modified elastomer carries along the main elastomer chain one or more pendant groups resulting from the grafting reaction of compounds of formula (I), in particular compound of formula (La) or (Ha), more particularly compound of formula (III), as defined above. Advantageously, these pendant groups are randomly distributed along the main elastomer chain.

[0156] According to a preferred embodiment, the molar rate of grafting of the compound of formula (I), in particular of the compound of formula (la) or (lia), more particularly of the compound of formula (III), is in the range of 0.01% to 15%, preferably of 0.05% to 10%, more preferably of 0.07% to 5%.

[0157] The term "grafting molar ratio" refers to the number of moles of compound of formula (I), in particular compound of formula (la) or (lia), more specifically compound of formula (III), grafted onto the elastomer per 100 moles of monomer unit constituting the initial elastomer. The grafting molar ratio can be determined by conventional methods of elastomer analysis, such as NMR analysis. 1 H.

[0158] The grafting of the compound of formula (I) and its preferred embodiments, in particular the compound of formulas (a1a), (lia), and (III), can be carried out in bulk, for example in an internal mixer or in an external mixer such as a roller mixer, or can be carried out in solution. The grafting process can be performed in solution continuously or batchwise. The modified elastomer can be separated from its solution by any means known to those skilled in the art, and in particular by steam stripping.

[0159] The invention also relates to a composition comprising at least one additive and at least one modified elastomer obtained by grafting the compound of formula (I), preferably the compound of formula (la) or (Ha), more preferably the compound of formula (III) as described above or obtained according to the process of the invention as described above.

[0160] The additives usable in the composition according to the invention may be plasticizers (such as plasticizing oils and / or plasticizing resins), fillers (reinforcing or non-reinforcing), pigments, protective agents such as ozone-blocking waxes, chemical ozone detoxifiers, antioxidants, anti-fatigue agents, reinforcing resins (such as those described, for example, in application WO 02 / 10269), a crosslinking system, for example, based on sulfur and other vulcanizing agents, and / or peroxide and / or bismaleimide. Preferably, this additive is a reinforcing filler; more preferably, this additive is an inorganic reinforcing filler; and even more preferably, this additive is silica.

[0161] EXAMPLES OF THE INVENTION'S IMPLEMENTATION

[0162] The following examples illustrate the invention, but the latter cannot be limited to these examples alone.

[0163] 1 - Synthesis of compounds:

[0164] Mesitylene, paraformaldehyde, hydrochloric acid, acetic acid, dichloromethane (DCM), petroleum ether, titanium tetrachloride, dichloromethyl methyl ether (DCMME), 2-methylimidazole, N,N-dimethylformamide (DMF), ethanol, T-hydroxylamine, sodium hypochlorite (NaOCl), allyl bromide, 2,4,6-trimethylphenol, potassium carbonate, anhydrous toluene, xylene, ethyl acetate, triethylamine, N-bromosuccinimide, sodium sulfate are marketed by Fisher Scientific.

[0165] Triethoxysilane, Karstedt catalyst, and dimethylethoxysilane are marketed by Merck.

[0166] 1.1 - Synthesis of compound A

[0167] The compound 1,3-dipolar N-oxide 2,4,6-trimethyl-3-((2-methyl-1H-imidazol-1-yl)methyl)benzonitrile (compound A) can be prepared according to the following reaction scheme:

[0168]

[0169] 1.1.1 - Synthesis of 2-(chloromethyl)-1,3,5-trimethylbenzene:

[0170] This compound can be obtained according to a procedure described in the following article: Zenkevich, I.

[0171] G.; Makarov, AA; Russian Journal of General Chemistry; flight. 77; nb. 4; (2007); p. 611 -619 (Zhurnal Obshchei Khimii; vol. 77; nb. 4; (2007); p. 653 - 662)

[0172] A mixture of mesitylene (100.0 g, 0.832 mol), paraformaldehyde (26.2 g, 0.874 mol), and hydrochloric acid (240 mL, 37%, 2.906 mol) in acetic acid (240 mL) is stirred and heated very slowly (1.5 hours) to 37°C. After returning to room temperature (23°C), the mixture is diluted with water (1.0 L) and CH2Cl2 (200 mL). The product is extracted with CH2Cl2 (4 times per 50 mL).

[0173] The organic phases are collected, then washed with water (5 times per 100 ml) and evaporated to 11-12 mbar (bath temperature = 42°C).

[0174] A colorless oil (133.52 g, 95% yield) is obtained. After 15-18 hours at a temperature of +4°C, the oil has crystallized. The crystals are filtered, washed with petroleum ether cooled to -18°C (40 ml), and then dried for 3 to 5 hours under atmospheric pressure at room temperature (23°C).

[0175] A white solid (95.9 g, yield 68%) with a melting point of 39 °C is obtained. The molar purity is greater than 96% (NMR ^j.

[0176] [Table 1]

[0177] Analysis performed in CDCh 1.1.2 - Synthesis of 3-(chloromethyl)-2,4,6-trimethylbenzaldehyde:

[0178] This compound can be obtained according to a procedure described in the following article: Yakubov, AP; Tsyganov, DV; Belen'kii, LI; Krayushkin, MM; Bulletin of the Academy of Sciences of the USSR, Division of Chemical Science (English Translation); vol. 40; nb. 7.2; (1991); p. 1427 - 1432 (Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya; nb. 7; (1991); p. 1609 - 1615)

[0179] A solution of TiCU (90.0 g, 0.474 mol) in dichloromethane (200 mL) at 17°C is added under argon for 10–12 minutes to a solution of 2-(chloromethyl)-1,3,5-trimethylbenzene (20.0 g, 0.118 mol) and dichloromethyl methyl ether (27.26 g, 0.237 mol) in dichloromethane (200 mL). After stirring for 15–20 minutes at 17–20°C, water (1000 mL) and ice (500 g) are added to the reaction mixture. After 10–15 minutes of stirring, the organic phase is separated. The aqueous phase is extracted with CH2Q2 (3 times per 75 mL). The collected organic phases are washed with water (4 times per 100 ml) and evaporated under reduced pressure to produce a solid (bath temperature = 28 °C).

[0180] The target product (22.74 g) is obtained with a yield of 97% and has a melting point of 58 °C. The molar purity was estimated by NMR. is 95%.

[0181] [Table 2] Analysis carried out in the CDCh

[0182] 1.1.3 - Synthesis of 2,4,6-trimethyl-3-((2-methyl-1H-imidazol-1-yl)methyl)benzaldehyde:

[0183] A mixture of 3-(chloromethyl)-2,4,6-trimethylbenzaldehyde (10.0 g, 0.051 mol) and 2-methylimidazole (10.44 g, 0.127 mol) in DMF (10 ml) is stirred at 80°C for one hour.

[0184] After cooling to 40-50°C, the mixture is diluted with water (200 mL) and stirred for 10 minutes. The resulting precipitate is filtered and washed with water (4 times per 25 mL) and then dried at room temperature (23°C). A white solid (7.92 g, 64% yield) with a melting point of 161°C is obtained. The molar purity is 91% (NMR). 1 H).

[0185] [Table 3]

[0186] 1.1.4 - Synthesis of 2,4,6-trimethyl-3-((2-methyl-1H-imidazol-1-yl)methyl)benzaldehyde oxime:

[0187] To a solution of 2,4,6-trimethyl-3-((2-methyl-1H-imidazol-1-yl)methyl)benzaldehyde (20.3 g, 0.084 mol) in ethanol (110 ml) at 40°C, an aqueous solution of hydroxylamine (809 g, 0.134 mol, 50% in water, Aldrich) in ethanol (10 ml) is added.

[0188] The reaction mixture is stirred for 2.5 hours at a temperature of 50°C to 55°C. After returning to a temperature of 23°C, the precipitate obtained is filtered and washed twice on the filter with an ethanol / water mixture (10 ml / 15 ml) and dried for 15 to 20 hours under atmospheric pressure at room temperature (23°C, 1 atm).

[0189] A white solid (19.57 g, 91% yield) with a melting point of 247°C is obtained. The molar purity is greater than 87%.

[0190] [Table 4]

[0191] 1.1.5 - Synthesis of 2,4,6-trimethyl-3-((2-methyl-1H-imidazol-1-yl)methyl)benzonitrile oxide:

[0192] To a mixture of 2,4,6-trimethyl-3-((2-methyl-1H-imidazol-1-yl)methyl)benzaldehyde oxime (8.80 g, 0.034 mol) in CH2Q2 (280 mL) at 6°C, an aqueous solution of NaOCl (4% active chlorine (w / w), 49 mL) is added dropwise over 5 minutes. The temperature of the reaction mixture is maintained between 6°C and 8°C. The reaction mixture is then stirred for 2 hours from 8°C to 21°C. The organic phase is separated.

[0193] The organic phase is washed with water (3 times per 50 mL). After concentration under reduced pressure (bath temperature = 22-23°C, 220 mbar), petroleum ether (10 mL) is added, the solvent is evaporated to 8-10 mL, and the solution is maintained at -18°C for 10-15 hours to obtain a precipitate. The precipitate is filtered and washed through a filter with a mixture of CH₂Q₂ / petroleum ether (2 mL / 6 mL), then with petroleum ether (2 x 10 mL), and finally dried for 10-15 hours under atmospheric pressure (1 atm) at room temperature (23°C).

[0194] A white solid (5.31 g, 61% yield) with a melting point of 139 °C is obtained. The molar purity is greater than 95% (NMR). 1 H).

[0195] [Table 5] 1.2 - Synthesis of compound B:

[0196] The 1,3-dipolar N-oxide compound of 3-(3-(Ethoxydimethylsilyl)propoxy)-2,4,6-trimethylbenzonitrile, compound B, is synthesized according to the following protocol:

[0197] 1.2.1 - Synthesis of 3-hydroxy-2,4,6-trimethylbenzaldehyde (product Bl):

[0198] Compound Bl can be obtained according to a procedure described in the following article: Yakubov, AP; Tsyganov, DV; Belen'kii, L. / .; Krayushkin, MM; Bulletin of the Academy of Sciences of the USSR, Division of Chemical Science (English Translation); vol. 40; nb. 7.2; (1991); p. 1427 - 1432; Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya; nb. 7; (1991); p. 1609 — 1615.

[0199] 1.2.2 - Synthesis of 3-(allyloxy)-2,4,6-trimethylbenzaldehyde (product Cl):

[0200] A suspension of compound B1 (19.0 g, 115.7 mmol), allyl bromide (15.4 g, 127.3 mmol), and potassium carbonate (14.4 g, 104.1 mmol) in DMF (80 mL) is heated to 75°C for 30–40 minutes. After 3–4 hours of stirring at this temperature and after returning to room temperature (23°C, 1 atm), the reaction mixture is filtered to remove the potassium carbonate. The filtrate is poured onto cold water at 3–4°C (700 mL). The target product is extracted four times per 100 mL of tert-butyl methyl ether.

[0201] The organic solutions are combined and washed twice with a 5% (w / mL) sodium hydroxide solution (50 mL) and then twice with water (50 mL). The organic solution is concentrated under reduced pressure (2 mbar, 40°C) to yield an oil (21.9 g).

[0202] After purification on a silica column (diameter 0.45 cm x 51 cm) using a mixture of ethyl acetate and petroleum ether as the eluent in a ratio of 1:20 to 1:15, the combined organic solutions were concentrated under reduced pressure (0 mbar, 40°C). A colorless oil (20.19 g) was obtained with a yield of 85.4% and a molar purity greater than 97% (NMR). 1 H).

[0203] [Table 6]

[0204] Analysis carried out in the CDCh

[0205] 1.2.3 - Synthesis of 3-(3-(ethoxydimethylsilyl)propoxy)-2,4,6-trimethylbenzaldehyde (product D): To a solution of 3-(allyloxy)-2,4,6-trimethylbenzaldehyde (compound Cl obtained previously) (6.00 g, 29.37 mmol) in anhydrous toluene (28 mL) at room temperature (23°C, 1 atm) under an argon atmosphere, dimethylethoxysilane (4.29 g, 41.12 mmol) is added. A solution of Karstedt catalyst (2.0%–2.4% wt. in xylene) (0.400 g) in anhydrous toluene (2 mL) is added in small portions over 10–15 minutes to the reaction mixture heated to 35°C.

[0206] After 10 minutes of stirring at this temperature, the reaction mixture is heated to 50–55°C. After 4 hours of stirring at this temperature, followed by a return to room temperature, the reaction mixture is concentrated under reduced pressure (9 mbar, 40°C) to yield an oil (9.5 g). This oil proceeds to the next step without further purification, achieving a purity of 73 molar (NMR). 1 H, CDCh).

[0207] [Table 7]

[0208] Analyses performed in CDCh

[0209] 1.2.4 - Synthesis of 3-(3-(ethoxydimethylsilyl)propoxy)-2,4,6-trimethylbenzaldehyde oxime, (product E):

[0210] To a solution of compound D obtained in the previous step (~29.4 mmol) in absolute ethanol (110 ml) at room temperature is added a 50% wt% hydroxylamine solution in water (2.91 g, 44.1 mmol) diluted in absolute ethanol (10 ml).

[0211] After 30-40 minutes of stirring at room temperature, the reaction mixture is concentrated under reduced pressure (20 mbar, 30°C) to yield a cloudy oil (11.55 g). This residue is then resuspended in petroleum ether (40 mL). The solution is filtered through a silica gel filter (diameter 0.35 cm, thickness 0.5-0.7 cm), and the residue is washed twice on the filter with petroleum ether (10 mL).

[0212] The solution is concentrated under reduced pressure (2 mbar, 30°C) to produce a colorless oil. The pure target product is obtained after purification on a silica column (diameter 0.45 cm x 47 cm; eluent ethyl acetate / petroleum ether: 1 / 10 to 18 (v / v)).

[0213] The solution is concentrated under reduced pressure (0 to 1 mbar, 40°C) to produce a colorless oil (4.547 g, 14.06 mmol) with a yield of 51% and a molar purity of 94%.

[0214] [Table 8]

[0215] Analyses performed in CDCh

[0216] 1.2.5 - Synthesis of 3-(3-(Ethoxydimethylsilyl)propoxy)-2,4,6-trimethylbenzonitrile N-oxide (compound B):

[0217] Triethylamine (1.99 g, 19.6 mmol) was added to a solution of compound E obtained in the previous step (4.52 g, 13.14 mmol) in dichloromethane (65 mL). The mixture was stirred under nitrogen and then cooled to 0–1°C. N-Chloro succinimide (2.11 g, 15.76 mmol) was then added to the mixture when the reaction temperature reached 0–1°C.

[0218] After 25-30 minutes of stirring at 0°C, the reaction mixture is washed twice with water (15 mL). The organic solution is dried over sodium sulfate and concentrated under reduced pressure (9 mbar, 18°C) to yield 5.41 g of a yellow / orange oil. This oil is reconstituted in a mixture of ethyl acetate (10 mL) and petroleum ether (60 mL). The solution is filtered through a silica gel (diameter 0.35 cm x 1.0 cm) and washed over a filter with a mixture of ethyl acetate (5 mL) and petroleum ether (25 mL). The colorless permeate is concentrated under reduced pressure (0 mbar, 18°C, 1 hour) to yield, with a 97% yield, an oil (12.78 mmol, 4.108 g) with a molar purity greater than [Table 9]

[0219] Analysis carried out in the CDCh

[0220] 1.3 - Characterization of the synthesized compounds:

[0221] Structural analysis and molar purity determination of the synthetic molecules are performed by NMR analysis. Spectra are acquired on a Bruker Avance 3400 MHz spectrometer equipped with a 5 mm BBFO-zgrad broadband probe. The quantitative ¹H NMR experiment uses a single 30° pulse sequence and a 3-second repetition delay between each of the 64 acquisitions. Samples are solubilized in a deuterated solvent, deuterated chloroform (CDCh), unless otherwise specified. The deuterated solvent is also used for the lock signal. For example, calibration is performed on the proton signal of deuterated CDCl3 at 7.20 ppm relative to a TMS reference at 0 ppm. The ¹H NMR spectrum is coupled to the 2D HSQC experiments. allow the structural determination of molecules. Molar quantifications are performed from the spectrum quantitative.

[0222] 2 - Synthesis of the elastomer:

[0223] The polymerization of ethylene (N35 grade from Air Liquide, used without prior purification) and 1,3-butadiene is carried out by a continuous process in solution in methylcyclohexane at 80°C under 11.5 bar in the presence of a catalytic system (94 pmoles Nd for 100 g of monomers), the mass concentration of monomer feed into the reactor being 6%, the mass ratio 1,3-butadiene / ethylene being 0.53, the molar ratio active Mg / Nd being 3.7. At the desired conversion (73%, 120 minutes) to reach a Mn of approximately 138000 g / mol, the polymerization is stopped at the line outlet using a solution of antioxidants in methylcyclohexane (0.6 pc of N-(l,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine and 0.7 pc of 2,2'-methylene-bis(4-methyl-6-tert-butylphenol).The copolymer is recovered by a steam stripping process, well known to those skilled in the art, and then dried on a screw conveyor equipped with a single screw. The catalytic system is a preformed catalytic system. It is prepared in methylcyclohexane from a metallocene, [Me2Si(Flu)2Nd(p-BH4)2i(THF)] at 0.0065 mol / L, a cocatalyst, butylmagnesium (BOMAG) with a BOMAG / Nd molar ratio of 2.2, and a preforming monomer, 1,3-butadiene with a 1,3-butadiene / Nd molar ratio of 90. The mixture is heated to 80°C for 5 hours. It is prepared according to a preparation method conforming to paragraph II.1 of document W02017093654AL.

[0224] The elastomer obtained has the following microstructure: 7 molar% of 1,4 polybutadiene unit, 11 molar% of 1,2 polybutadiene, 75 molar% of ethylene and 7 molar% of 1,2-cyclohexanediyl unit.

[0225] The elastomer has a Tg of -43°C, a Mn of 138000 g / mol measured by the method described below, and a Mooney (ML (1+4)) at 100°C of 64 UM (see measurement method below).

[0226] 3 - Determination of the microstructure of elastomers:

[0227] The microstructure of elastomers is determined by NMR analysis 1 H, supplemented by NMR analysis 13 This is used when the resolution of the NMR spectra does not allow for the assignment and quantification of all species. Measurements are performed using a BRUKER 500 MHz NMR spectrometer at frequencies of 500.43 MHz for proton observation and 125.83 MHz for carbon observation. A liquid NMR probe enabling observation of both protons and carbon in proton-decoupled mode is employed.

[0228] The preparation of insoluble samples is carried out in rotors filled with the material to be analyzed and a deuterated solvent that induces swelling, generally deuterated chloroform (CDCL). The solvent used must always be deuterated, and its chemical composition can be adapted by those skilled in the art. The quantities of material used are adjusted to obtain spectra with sufficient sensitivity and resolution.

[0229] Soluble samples are dissolved in a deuterated solvent (approximately 25 mg of elastomer in 1 ml), generally deuterated chloroform (CDCL). The solvent or solvent cutting agent used must always be deuterated, and its chemical composition can be adapted by a person skilled in the art.

[0230] In both cases (soluble sample or swollen sample):

[0231] For proton NMR, a single 30° pulse sequence is used. The spectral window is adjusted to observe all the resonance lines belonging to the analyzed molecules. The accumulation number is set to obtain a signal-to-noise ratio sufficient for quantifying each motif. The recycling time between each pulse is adjusted to obtain a quantitative measurement.

[0232] For carbon NMR, a simple 30° pulse sequence is used with proton decoupling only during acquisition to avoid Nuclear Overhauser Effects (NOE) and maintain quantitative accuracy. The spectral window is adjusted to observe all resonance lines belonging to the analyzed molecules. The accumulation number is set to obtain a signal-to-noise ratio sufficient for quantifying each motif. The recycle time between each pulse is optimized for quantitative measurement.

[0233] NMR measurements are performed at 25°C.

[0234] 4 - Determination of the Tg of elastomers:

[0235] The glass transition temperature (Tg) values ​​described herein are measured in a known manner by DSC (Differential Scanning Calorimetry) according to ASTM D3418-2008.

[0236] 5- Determination of the Mn of elastomers:

[0237] Measurement of Mn, Mw and Ip of elastomers by triple-detection size exclusion chromatography (SEC-3D)

[0238] The number-average molar mass (Mn), and where applicable the weight-average molar mass (Mw) and the polydispersity index (Ip) of the elastomers are determined in a known manner, by triple-detection size exclusion chromatography “SEC-3D” (SEC: “Size Exclusion Chromatography”).

[0239] Triple detection size exclusion chromatography has the advantage of measuring average molar masses directly without calibration.

[0240] The refractive index increment dn / dc of the sample is determined first. To do this, the sample is first solubilized in tetrahydrofuran at precisely known concentrations (0.5 g / L, 0.7 g / L, 0.8 g / L, 1 g / L, and 1.5 g / L). Each solution is then filtered through a 0.45 µm pore size filter. Each solution is then injected directly, using a syringe pump, into a Wyatt Technology differential refractometer, commercially known as the "OPTILAB T-REX," with a wavelength of 658 nm and a temperature of 35°C. The refractive index is measured by the refractometer at each concentration. Wyatt Technology's "ASTRA" software plots the detector signal against the sample concentration.The "ASTRA" software automatically determines the slope of the line corresponding to the refractive index increment of the sample in tetrahydrofuran at 35°C and a wavelength of 658 nm.

[0241] To determine the average molar masses, the previously prepared and filtered 1 g / L solution is injected into the chromatographic system. The equipment used is a WATERS alliance chromatographic system. The elution solvent is oxidized tetrahydrofuran, with 250 ppm BHT (2,6-diter-butyl 4-hydroxytoluene), at a flow rate of 1 mL / min. 1The system temperature was 35°C and the analysis time 60 min. The columns used were a set of three AGILENT columns, commercially known as "PL GEL MIXED B LS". The injected volume of the sample solution was 100 µL. The detection system consisted of a Wyatt Technology differential viscometer, commercially known as "VISCOSTAR II", a Wyatt Technology differential refractometer, commercially known as "OPTILAB T-REX" with a wavelength of 658 nm, and a Wyatt Technology multi-angle static light scattering detector, commercially known as "DAWN HELEOS 8+", with a wavelength of 658 nm.

[0242] For the calculation of the number-average molar masses and the polydispersity index, the value of the refractive index increment dn / dc of the sample solution obtained above is incorporated. The chromatographic data processing software is the "ASTRA" system from Wyatt Technology.

[0243] 6 - Determination of the Mooney viscosity ML(l+4) at 100°C according to ASTM D-1646 for elastomers:

[0244] A consistometer is used as described in ASTM D-1646 (1999). The Mooney viscosity measurement is performed according to the following principle: the elastomer is molded in a cylindrical chamber heated to 100 °C. After one minute of preheating, the rotor rotates within the specimen at 2 revolutions per minute, and the torque required to maintain this rotation after 4 minutes of rotation is measured. The Mooney viscosity (ML(l+4)) is expressed in Mooney Units (MU, with 1 MU = 0.83 Nm).

[0245] 7 - Grafting the compounds onto an elastomer:

[0246] 7.1 - Elastomer grafted with compound A:

[0247] Compound A (N-oxide 2,4,6-trimethyl-3-((2-methyl-1H-imidazol-1-yl)methyl)benzonitrile) obtained according to the process described in paragraph 1.1 (0.3% mol i.e. 2.12 g) is incorporated into 100 g of EBR elastomer obtained according to the process described in paragraph 2.

[0248] The incorporation is carried out using a roller tool (external mixer at 30°C). The mixture is homogenized fifteen times on this tool.

[0249] This mixing phase is followed by a heat treatment (10 min at 120°C) under a press at 10 bars of pressure.

[0250] Following the two processing steps, the analysis by NMR enabled the determination of a molar rate of grafted nitrile oxide (CNO) function of 0.16 mol%, i.e. a molar grafting yield of 80%.

[0251] 7.2 - Elastomer grafted with compound B:

[0252] Compound B (3-(3-(Ethoxydimethylsilyl)propoxy)-2,4,6-trimethylbenzonitrile N-oxide) obtained according to the process described in paragraph 1.3 (0.3% mol i.e. 2.65 g) is incorporated into 100 g of EBR obtained according to the process described in paragraph 2.

[0253] The incorporation is carried out using a roller tool (external mixer at 30°C). The mixture is homogenized fifteen times on this tool.

[0254] This mixing phase is followed by heat treatment (10 min at 100°C) under pressure from a press at 10 bar. Following the two treatment stages, NMR analysis determined a molar grafting rate of 0.16 mol% with a molar grafting yield of 80%.

[0255] 7.3 - Characterization of compounds grafted onto diene elastomers:

[0256] The molar content of compounds grafted onto diene elastomers was determined by NMR analysis. Spectra were acquired on a 500 MHz BRUKER spectrometer equipped with a CryoSonde BBFO-zgrad-5 mm. The quantitative ¹H NMR experiment used a single 30° pulse sequence with a 5-second repetition interval between acquisitions. Samples were solubilized in deuterated chloroform (CDCh) to obtain a lock signal. 2D NMR experiments were used to verify the nature of the grafted motif by observing the chemical shifts of carbon and proton atoms.

[0257] 8 - Obtaining elastomeric compositions:

[0258] The elastomeric compositions, the detailed formulation of which is shown in the table below, were prepared as follows:

[0259] The grafted or ungrafted elastomer is introduced into an internal mixer (final filling rate: approximately 70% by volume), the initial temperature of which can be between 80°C and 100°C. Silica, carbon black, and the coupling agent for the inorganic filler are then added to the elastomer. After one to two minutes of mixing, the various other ingredients are added, with the exception of sulfur and the vulcanization accelerator. A thermomechanical process (non-productive phase) is then carried out in a single step, lasting approximately 5 to 6 minutes in total, until a maximum "drop" temperature of 160°C is reached.

[0260] The mixture thus obtained is collected, cooled, and then sulfur and vulcanization accelerator are incorporated on a roller tool at 23°C, mixing the mixture and these ingredients (productive phase) for an appropriate time of 8 minutes.

[0261] The compositions thus obtained are then calendered from thin plates or sheets to measure their physical or mechanical properties.

[0262] The crosslinking was then carried out at a temperature of 150°C for 90 min, under pressure.

[0263] 9 - Dynamic properties of elastomeric compositions:

[0264] Dynamic properties are measured on a viscoelastic analyzer (Metravib VA4000), according to ASTM D 5992-96. The response of a cross-linked composition sample (a 4 mm thick cylindrical specimen molded between 3 coated steel blocks and 10 mm in diameter) is recorded, subjected to sinusoidal loading in alternating simple shear, at a frequency of 10 Hz, under defined temperature conditions (e.g., 60°C or 100°C) according to ASTM D 1349-99. A strain amplitude sweep is performed from 0.1% to 100% (forward cycle), then from 100% to 0.1% (reverse cycle). The results used are the complex shear modulus G*, the loss factor tan(θ), and the modulus difference AG* between the values ​​of 0.1% and 100% strain (Payne effect), on the return cycle.

[0265] For the return cycle, we indicate the maximum value of tan(ô) observed at 60°C (noted tan(ô)max at 60°C) and the maximum value of tan(ô) observed at 100°C, noted tan(ô)max at 100°C; as well as the modulus G* at 25% deformation noted G*25% return at 60°C.

[0266] The G*25% values ​​returning to 60°C are representative of the stiffness

[0267] The values ​​of tan(ô) max return at 60°C and tan(ô) max return at 100°C are representative of the hysteresis.

[0268] The results are shown in base 100; the arbitrary value 100 is assigned to the control to calculate and then compare tan(ô) ma x at 100°C, tan(ô) ma x at 00°C, G*25% return at 00°C and AG* of the different samples tested.

[0269] For tan(ô) ma x at 60°C, the value in base 100 for the sample to be tested is calculated according to the operation: (value of tan(θ) ma x at 60°C of the sample to be tested / value of tan(θ) max at 60°C of the control) x 100. The same calculation is performed with tan(θ) ma x at 100°C In this way, a result less than 100 indicates a decrease in hysteresis which corresponds to an improvement in rolling resistance performance.

[0270] For G*25% return at 60°C, the value in base 100 for the sample to be tested is calculated according to the operation: (value of G*25% return at 60°C of the sample to be tested / value of G*25% return at 60°C of the control) x 100. In this way, a result greater than 100 indicates an improvement in the complex dynamic shear modulus G*25% return at 60°C, which corroborates an improvement in the stiffness of the material.

[0271] For (AG*), the value in base 100 for the sample to be tested is calculated according to the operation: (value of AG* of the sample to be tested / value of AG* of the control) x 100. In this way, a result less than 100 reflects a decrease in the deviation of the modulus, i.e. an increase in the linearization of the elastomeric composition, i.e. a better dispersion of the reinforcing charge in the composition.

[0272] 10 - Tensile properties of elastomeric compositions:

[0273] These tensile tests determine the breaking properties. Unless otherwise specified, they are carried out in accordance with the French standard NF T 46-002 of September 1988.

[0274] The breaking stresses (in MP a) are measured at 100°C ± 2°C according to standard NF T 46- 002 and in true secant modulus.

[0275] The results are presented on a base of 100, with the arbitrary value 100 being assigned to the control to calculate and compare to the value of the composition tested: (value of the tensile strength of the sample to be tested / value of the tensile strength of the control) x 100. In this way, a result greater than 100 indicates an improvement in the tensile strength property.

[0276] 11- Test: This test aims to show that the modified diene elastomer according to the invention obtained by grafting compound B gives the elastomeric compositions containing it a very good compromise of properties between the properties of breaking strength, hysteresis and stiffness, while maintaining a good dispersion of the reinforcing charge.

[0277] The proportions of the different constituents of these compositions, expressed in parts per cent parts per hundred weight of elastomer, are presented in the table below.

[0278] The mechanical properties of the elastomeric compositions measured after baking are presented in the table below.

[0279] [Table 10]

[0280] (1) Non-grafted diene elastomer (Elastomer outside the scope of invention)

[0281] (2) Diene elastomer grafted with compound A according to the process described in paragraph 7.1 (Elastomer not part of the invention)

[0282] (3) Diene elastomer grafted with compound B according to the process described in paragraph 7.2 (Elastomer according to the invention)

[0283] (4) Silica “Zeosil 1165MP” marketed by Solvay

[0284] (5) ASTM N234 grade carbon black (ASTM D1765-17) marketed by Cabot Corporation

[0285] (6) Coupling agent of the inorganic reinforcing agent to the elastomer: Bis[3-(triethoxysilyl)propyl] Tetrasulfide silane (TESPT) marketed by Evonik under the reference “Si69”

[0286] (7) Anti-ozone wax: “Varazon 4959” wax from Sasol Wax

[0287] (8) Antioxidant: ((N-(l,3-dimethylbutyl)-N-phenyl-para-phenylenediamine marketed under the reference "Santaflex 6-PPD" by the company Flexsys

[0288] (9) Stearic acid marketed under the reference "Pristerene 4931" by the company Uniqema

[0289] (10) Industrial grade zinc oxide marketed by Umicore

[0290] (11) Accelerator: N-cyclohexyl-2-benzothiazyl-sulfenamide: “Santocure CBS” from Flexsys. In the presence of a coupling agent for the inorganic reinforcing filler to the diene elastomer, the elastomer modified by grafting compound B (elastomer according to the invention) yields an elastomeric composition (composition Cl) exhibiting improved linearity (Paye effect) and a good compromise of hysteresis / stiffness / tensile strength properties compared to an elastomeric composition (composition Tl) not comprising a grafted diene elastomer. These observed improvements in properties are of the same order of magnitude as the improvement observed for an elastomeric composition comprising a diene elastomer grafted with a prior art 1,3-dipolar compound (comparison of compositions T3 versus Tl).

[0291] When the coupling agent of the inorganic reinforcing filler with F diene elastomeric in the elastomeric compositions (Compositions T2, T4 and C2) is removed, only the elastomeric composition comprising the diene elastomer grafted according to the invention (composition C2) exhibits an improvement in the stress-at-break properties while retaining the improvement in linearity and the compromise of hysteresis / stiffness properties (see composition C2 versus Cl).

[0292] Thus, the diene elastomer grafted according to the invention makes it possible to give the elastomeric compositions containing it a very good compromise of tensile strength, hysteresis and stiffness properties, while maintaining good dispersion of the reinforcing filler including when the elastomeric composition includes a small amount or no coupling agent of the inorganic reinforcing filler to the diene elastomer.

Claims

DEMANDS 1) Modified elastomer obtained by grafting at least one compound of formula (I) onto at least one unsaturation of an initial elastomer (D in which: A represents an arenediyl ring in CÔ-CU, possibly substituted by one or more hydrocarbon chains, identical or different, aliphatic, preferably saturated, linear or branched; E represents a divalent hydrocarbon group in the C2-C12 range, possibly comprising one or more heteroatoms; and Ra, Rb, Rc, whether identical or different, represent an alkyl in C1-CO. 2) Modified elastomer according to claim 1, wherein E represents a divalent hydrocarbon group in C2-C10, preferably in C2-C9, more preferably in C2-C7, more preferably still in C2-C5. 3) Modified elastomer according to any one of the preceding claims, in which E represents a C2-C10 alkanediyl, preferably a C2-C9 alkanediyl, more preferably a C2-C7 alkanediyl, more preferably still a C2-C5 alkanediyl. 4) Modified elastomer according to any one of the preceding claims, wherein Ra, Rb, Rc, identical or different, represent a C1-C4 alkyl. 5) Modified elastomer according to any one of the preceding claims, wherein Ra and Rb are identical and are a C1-C4 alkyl, preferably methyl, and Rc is ethyl. 6) Modified elastomer according to any one of the preceding claims, wherein the compound of formula (I) is selected from the compounds of formula (la) and (lia) in which (i) a grouping chosen from Ri to R5 of formula (la) and a grouping chosen from Ri to R7 of formula (lia) denote the following group of formula (II): wherein E, Ra, Rb, Rc are as defined in any one of claims 1 to 5 and the symbol (*) represents attachment to (la) or to (Ha), and (ii) the four groups of formula (la) selected from Ri to R5 other than that designating formula group (II) and the six groups of formula (lia) selected from Ri to R7 other than that designating formula group (II), whether identical or different, independently represent a hydrogen atom or an aliphatic hydrocarbon chain, preferably saturated, linear or Ci-C branched 24 . 7) Modified elastomer according to claim 1, which compound of formula (I) is the compound of formula (III) (HD 8) Modified elastomer according to any one of the preceding claims, wherein the initial elastomer is a diene elastomer. 9) Modified elastomer according to claim 8, wherein the diene elastomer is selected from homopolymers of a diene monomer, conjugated or not, having from 4 to 12 carbon atoms, copolymers of a diene monomer, conjugated or not, having from 4 to 12 carbon atoms and at least one other monomer selected from the group consisting of ethylene, vinylaromatic compounds having from 8 to 20 carbon atoms, aliphatic alpha-monoolefins having from 3 to 12 carbon atoms and diene monomer, conjugated or not, having from 4 to 18 carbon atoms, and mixtures of these homopolymers and copolymers. 10) Modified elastomer according to claim 8 or 9, wherein the diene elastomer is selected from homopolymers of 1,3-diene monomers, copolymers of 1,3-diene monomers and at least one other monomer selected from the group consisting of ethylene, styrene, propylene and 1,3-diene monomers, and mixtures of these homopolymers and copolymers. 11) Modified elastomer according to claim 10, wherein the 1,3-diene monomer is selected from the group consisting of 1,3-butadiene, isoprene and mixtures thereof. 12) Modified elastomer according to any one of the preceding claims, wherein the molar rate of grafting of the compound of formula (I) is in the range of 0.01% to 15%, preferably 0.05% to 10%, more preferably 0.07% to 5%. 13) Process for preparing a modified elastomer, said process comprising a step of grafting a compound of formula (I) onto an initial elastomer comprising at least one unsaturation by cycloaddition [3+2] of the nitrile oxide of the compound of formula (I) onto said unsaturation, in which: A represents an arenediyl ring in CÔ-CU, possibly substituted by one or more hydrocarbon chains, identical or different, aliphatic, preferably saturated, linear or branched; E represents a divalent hydrocarbon group in the C2-C12 range, possibly comprising one or more heteroatoms; and Ra, Rb, Rc, whether identical or different, represent an alkyl in C1-CO. 14) A method for preparing a modified elastomer according to claim 13, wherein the initial elastomer is a diene elastomer, preferably a diene elastomer selected from homopolymers of a diene monomer, conjugated or not, having from 4 to 12 carbon atoms, and copolymers of a diene monomer, conjugated or not, having from 4 to 12 carbon atoms and at least one other monomer selected from the group consisting of ethylene, vinylaromatic compounds having 8 to 20 carbon atoms and aliphatic alpha-monoolefins having 3 to 12 carbon atoms, conjugated or unconjugated diene monomers having 4 to 18 carbon atoms, and mixtures of these homopolymers and copolymers. 15) Composition comprising at least one additive and at least one modified elastomer as defined in any one of claims 1 to 12 or obtained according to the process of any one of claims 13 to 14.

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