Rubber composition

Abstract

The present invention relates to a rubber composition comprising an elastomer that is a copolymer containing more than 50 mol % ethylene units, containing units of 1,3-diene and carrying pendant groups with N-substituted imidazole functionality, a vulcanization system, a reinforcing filler containing silica, and an organofunctional silane coupling agent having at least one blocked thiol functionality, at least one thiol functionality, and at least one functional group that is a hydroxyalkoxysilyl or cyclic dialkoxysilyl group. Such a composition has improved properties at break in the cured state.

Description

[Technical field]

[0001] The field of the invention is rubber compositions comprising silica and highly saturated diene elastomers, particularly intended for use in the manufacture of tires. [Background technology]

[0002] Rubber compositions reinforced with silica and comprising highly saturated diene elastomers are known from the documents WO2014114607 and WO2018224776. Highly saturated diene elastomers are copolymers of ethylene and 1,3-diene, such as 1,3-butadiene, with the particularity of containing more than 50 mol% ethylene units. Due to their high ethylene content and their low diene unit content of less than 50 mol%, they are very different from diene elastomers customarily used in rubber compositions and generally containing more than 50 mol% diene units, such as polybutadiene, polyisoprene and copolymers of 1,3-butadiene or isoprene with styrene. In particular, they have the particularity of giving the rubber composition a different compromise of properties between stiffness and hysteresis. There remains a need to further improve the rupture properties of rubber compositions reinforced with silica and containing highly saturated diene elastomers. Summary of the Invention

[0003] We have discovered new rubber compositions which are silica reinforced and contain highly saturated diene elastomers, which in the cured state exhibit improved properties at break. Thus, the present invention provides a functional highly saturated diene elastomer which is a copolymer containing ethylene units and 1,3-diene units and carrying pendent groups containing N-substituted imidazole functional groups, the ethylene units representing more than 50 mol % of the constituent repeat units of the functional highly saturated diene elastomer, - Vulcanization systems, - reinforcing fillers containing silica, as well as organofunctional silane coupling agents containing at least one blocked thiol functional group, at least one thiol functional group and at least one functional group which is a hydroxyalkoxysilyl group or a cyclic dialkoxysilyl group, said organofunctional silane coupling agents corresponding to formula (1) The present invention relates to a rubber composition comprising: (A) p (B) q (1) (wherein A and B represent a blocked mercaptosilane unit corresponding to formula (2) and a mercaptosilane unit corresponding to formula (3), respectively.

[0004] [ka] TIFF2024542524000002.tif3370(in the formula, R3 is a hydrogen atom, a linear or branched C1-C 18 Alkyl, linear or branched C2-C 18 alkenyl, Each R4 is independently selected from a linear or branched, saturated C1-C6 divalent hydrocarbon-based group; Each Z unit may be the same or different, and forms a bridge structure between a silicon atom of one unit and a silicon atom of another unit. b is (-O-) 0.5 and [-O(R 0 CR 0 ) f O-] 0,5 are independently selected from the symbol R 0 may be the same or different and each represents a hydrogen atom or a C1-C3 alkyl; f is a number ranging from 2 to 15; Each Z unit forms a ring structure with a silicon atom c is the formula [-O(R 0 CR 0 ) f O-] 0.5 is a group of R 0 and f is as defined above, Each X is a hydrogen atom, a hydroxyl group, a C1-C6 alkyl group, a C1-C6 alkoxy group, or a group of the formula HO(R 0 CR 0 ) f R is independently selected from the group consisting of O-, 0 and f is as defined above, u+v+2w=3, where u is a number equal to 0, 1, 2 or 3, v is a number equal to 1, 2 or 3, and w is a number equal to 0 or 1; p is a number in the range of 1 to 20; q is a number in the range of 1 to 20) The present invention also relates to a tire comprising, preferentially in its tread, a rubber composition according to the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0005] Any interval of values ​​indicated by the expression "from a to b" denotes a range of values ​​greater than "a" and less than "b" (i.e., the limiting values ​​a and b are excluded), whereas any interval of values ​​indicated by the expression "a to b" means a range of values ​​extending from "a" to "b" (i.e., including the strict limiting values ​​a and b). The abbreviation "phr" means parts by weight per 100 parts of elastomer (of all elastomers if several elastomers are present). The compounds mentioned herein may be of fossil origin or may be bio-based. In the latter case, they may be partially or completely derived from biomass or may be obtained from renewable starting materials originating from biomass. Likewise, the compounds mentioned may also originate from recycling of already used materials, i.e. they may be partially or completely derived from regeneration processes or may be obtained from the starting materials themselves originating from regeneration processes.

[0006] In the present invention, the term "tire" is understood to mean a pneumatic or non-pneumatic tire. A pneumatic tire usually comprises two beads intended to come into contact with the rim, a crown consisting of at least one crown reinforcement and a tread, two sidewalls and a tire reinforced by a carcass reinforcement fixed to the two beads. A non-pneumatic tire, for its part, usually comprises a base, for example designed to be fixed on a rigid rim, a crown reinforcement that ensures a connection with the tread and a deformable structure, for example spokes, ribs or cells, the structure of the crown reinforcement being arranged between the base and the crown. Such a non-pneumatic tire does not necessarily comprise a sidewall. Non-pneumatic tires are described, for example, in WO 03 / 018332 and in FR 2 898 077. According to any one of the embodiments of the invention, the tire according to the invention is preferentially a pneumatic tire.

[0007] Unless otherwise indicated, the content of a unit within a polymer, such as a functional highly saturated diene elastomer useful in the present invention, is expressed as a mole percentage compared to the total constituent repeat units (also referred to by the abbreviation CRU in IUPAC) of the polymer. The elastomers useful for the purposes of the present invention are functional highly saturated diene elastomers, which preferably contain ethylene units resulting from the polymerization of ethylene. In known manner, the expression "ethylene units" refers to -(CH2-CH2)- units resulting from the insertion of ethylene into the elastomer chain. The functional highly saturated diene elastomers are rich in ethylene units, since they represent more than 50 mol% of the constituent repeat units of the functional highly saturated diene elastomer. Preferably, the functional highly saturated diene elastomer comprises at least 60 mol % of ethylene units, preferentially at least 65 mol % of ethylene units, more preferentially at least 70 mol % of ethylene units. Preferably, the highly saturated functional diene elastomer comprises at most 90 mol % of ethylene units. More preferentially, the diene elastomer comprises at most 85 mol % of ethylene units. Even more preferentially, the diene elastomer comprises at most 80 mol % of ethylene units.

[0008] According to an advantageous embodiment, the highly saturated diene functional elastomer comprises 60 mol % to 90 mol % of ethylene units, in particular 60 mol % to 85 mol % of ethylene units, and more advantageously 60 mol % to 80 mol % of ethylene units. According to another advantageous embodiment, the highly saturated diene functional elastomer comprises 65 mol % to 90 mol % of ethylene units, in particular 65 mol % to 85 mol % of ethylene units, and more advantageously, the highly saturated diene functional elastomer comprises 65 mol % to 80 mol % of ethylene units. According to yet another advantageous embodiment of the invention, the highly saturated diene functional elastomer comprises 70 mol % to 90 mol % of ethylene units, in particular 70 mol % to 85 mol % of ethylene units, and more advantageously 70 mol % to 80 mol % of ethylene units. The highly saturated functional diene elastomers contain 1,3-diene units. In a known manner, the term "1,3-diene units" or "diene units" refers to units resulting from the insertion of 1,3-dienes via 1,4-addition, 1,2-addition or 3,4-addition, for example in the case of isoprene. The 1,3-diene units are, for example, 1,3-dienes containing from 4 to 12 carbon atoms, such as 1,3-butadiene, isoprene, 1,3-pentadiene or aryl-1,3-butadiene. Preferably, the 1,3-diene is 1,3-butadiene or a mixture of 1,3-dienes, one of which is 1,3-butadiene. More preferentially, the 1,3-diene is 1,3-butadiene. The functional highly saturated diene elastomer preferably comprises units of formula (I) or units of formula (II).

[0009] [ka]

[0010] The presence of the saturated 6-membered ring unit of formula (I), 1,2-cyclohexanediyl, in the functional highly saturated diene elastomer may result from a series of highly specific insertions of ethylene and 1,3-butadiene into the growing polymer chain. When the functional highly saturated diene elastomer contains units of formula (I) or units of formula (II), the mole percentages o and p of the units of formula (I) and units of formula (II) in the functional highly saturated diene elastomer preferably satisfy the following equation (eq.1) or equation (eq.2), respectively, where o and p are calculated based on the total constituent repeat units of the functional highly saturated diene elastomer. 0 <o+p≦30 (eq.1) 0 <o+p<25 (eq.2) Preferably, the functional highly saturated diene elastomer comprises units of formula (I) in a molar content greater than 0 mol% and less than 15 mol%, more preferentially less than 10 mol%, calculated based on all constituent repeat units of the functional highly saturated diene elastomer. These preferential ranges of the molar content of units of formula (I) can be applied to any one of the embodiments of the present invention.

[0011] The functional highly saturated diene elastomer is also characterized by carrying pendant groups containing N-substituted imidazole functional groups. The skilled person will understand that the pendant groups are attached to the elastomer by covalent bonds. The pendant groups containing imidazole functional groups according to the present invention are preferably randomly arranged pendant groups in the functional highly saturated diene elastomer. Preferably, the content of imidazole functional groups in the functional highly saturated diene elastomer is less than 3 mol% of the constituent repeat units of the functional highly saturated diene elastomer. Usually, the content is greater than 0 mol% and preferentially less than 3 mol%, more preferentially greater than 0.02 mol% and less than 2 mol%, and even more preferentially greater than 0.07 mol% and less than 0.7 mol%, calculated based on the total constituent repeat units of the functional highly saturated diene elastomer. These preferential ranges of the molar content of imidazole functional groups can be applied to any one of the embodiments of the present invention. The N-substituted imidazole function is preferentially a group of formula (4).

[0012] [ka] (wherein, symbol Y1 represents a hydrogen atom or an alkyl having 1 to 6 carbon atoms, symbol Y2 represents a bond to a diene unit of a functional highly saturated diene elastomer, and symbols Y3 and Y4 each represent a hydrogen atom.) Advantageously, the functional group is a group of formula (4) in which the alkyl represented by Y1 contains from 1 to 3 carbon atoms and is preferably methyl. The term "bond to a diene unit of a functional highly saturated diene elastomer" is understood to mean a bond or a group capable of covalently linking the five-membered ring of the imidazole functionality to said unit. According to one embodiment of the present invention, the functional highly saturated diene elastomer is a copolymer of ethylene and a 1,3-diene modified by reacting a modifying agent containing groups reactive towards diene units and containing an imidazole functionality of formula (5).

[0013] [ka] (wherein, symbol Z1 represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, symbol Z2 represents a bond to a reactive group, and symbols Z3 and Z4 each represent a hydrogen atom). According to this embodiment, the units attached to the N-substituted imidazole functional groups are diene units modified by reaction of a modifier, and the functional highly saturated diene elastomer is obtained by modifying a highly saturated diene elastomer, called the starting highly saturated diene elastomer, by reaction of grafting the modifier to the 1,3-diene units of the starting highly saturated diene elastomer, resulting in the presence of unmodified 1,3-diene units and modified 1,3-diene units in the functional highly saturated diene elastomer. The reactive group of the modifier can be a dipole capable of reacting with a carbon-carbon double bond, for example a 1,3-diene unit. The dipole can be a nitrile oxide, nitrone or nitrile imine group.

[0014] The modifier is preferentially a 1,3-dipolar nitrile oxide, nitrone or nitrile imine compound, then the reactive group of the modifier is a nitrile oxide, nitrone or nitrile imine, and even more preferentially a nitrile oxide. The term "1,3-dipolar compound" is understood according to the definition given by IUPAC. 1,3-dipolar compounds are characterized by containing a dipole, a nitrile oxide, nitrone or nitrile imine and an imidazole function. The dipole constitutes the reactive group of the modifier towards the diene unit. The dipole usually reacts with the diene unit in particular by a [3+2] cycloaddition reaction. More preferentially, the modifier is a 1,3-dipole compound which is an aromatic nitrile monoxide, a compound containing a benzene ring substituted with a nitrile oxide dipole and substituted with a group containing an imidazole function of formula (5).

[0015] [ka] (wherein the symbol Z1 represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, the symbol Z2 represents a bond to a dipole, and the symbols Z3 and Z4 each represent a hydrogen atom). The term "aromatic nitrile monoxide compound" is understood to mean an aromatic compound containing one nitrile oxide dipole and in which the benzene ring is substituted with the nitrile oxide dipole, meaning that the carbon atom of the dipole is directly bonded to the carbon atom of the benzene ring via a covalent bond. The benzene ring substituted with the nitrile oxide dipole is also substituted with a group containing an imidazole function. Preferably, the benzene ring is also substituted with the dipole in the ortho position. Advantageously, the 1,3-dipole compound contains a unit of formula (6).

[0016] [ka] (wherein R'1 represents a nitrile oxide dipole, one of the symbols R'2 to R'6 represents a saturated group having 1 to 6 carbon atoms and covalently bonded to one of the nitrogen atoms of the 5-membered ring of the imidazole functional group of formula (5), and the other symbols may be the same or different and represent a hydrogen atom or a substituent.) The substituents in formula (6) can be any group as long as they do not react with the dipole. The substituents in formula (6) can form a ring with the substituents on adjacent carbons. Preferably, the substituents in formula (6) are alkyl groups having 1 to 3 carbon atoms, preferentially methyl or ethyl, more preferentially methyl.

[0017] The saturated group in formula (6) allows the imidazole function to be covalently linked to a benzene ring substituted in particular with a nitrile oxide dipole. The saturated group may contain one or more heteroatoms. The saturated group preferentially contains 1 to 3 carbon atoms. The saturated group in formula (6) is preferably alkanediyl, more preferentially alkanediyl having 1 to 3 carbon atoms, even more preferentially methanediyl. In formula (6), R'2 and R'6 are preferentially different from a hydrogen atom. Preferably, R'2, R'4 and R'6 are all the same and different from a hydrogen atom. The synthesis of 1,3-dipole compounds can be carried out using a relatively easy synthetic route using commercially available precursors, such as mesitylene, as described in particular in document WO 2015 / 059269. Advantageously, the 1,3-dipole compound is a compound of formula (7), 2,4,6-trimethyl-3-((2-methyl-1H-imidazol-1-yl)methyl)benzonitrile oxide, or a compound of formula (8), 2,4,6-triethyl-3-((2-methyl-1H-imidazol-1-yl)methyl)benzonitrile oxide, more advantageously a compound of formula (7).

[0018] [ka] According to a preferential variant of the invention, the functional highly saturated diene elastomer is a modified highly saturated diene elastomer since it can be obtained by modification of a starting highly saturated diene elastomer in which part of the diene units is modified by grafting with the abovementioned modifiers. The modification can be carried out in bulk or in solution. The functional highly saturated diene elastomer is preferentially a modified copolymer of ethylene and 1,3-dienes or a copolymer of ethylene and several 1,3-dienes, the 1,3-dienes being advantageously 1,3-butadiene or a mixture of 1,3-dienes, one of which being 1,3-butadiene. The functional highly saturated diene elastomer is more preferentially a modified copolymer of ethylene and 1,3-butadiene. Advantageously, the functional highly saturated diene elastomer is a modified statistical copolymer.

[0019] The starting highly saturated diene elastomer can be obtained according to various synthesis methods known to those skilled in the art, depending in particular on the targeted microstructure of the functional highly saturated diene elastomer.Generally, it can be prepared by copolymerization of at least one 1,3-diene, preferably 1,3-butadiene, and ethylene, according to known methods of synthesis, in the presence of a catalytic system, in particular comprising a metallocene complex.In this respect, mention can be made of catalytic systems based on metallocene complexes, which are described in EP 1092731, WO 2004 / 035639, WO 2007 / 054223 and WO 2007 / 054224 in the name of the applicant. The starting highly saturated diene elastomer, including the statistical case, can also be prepared via a method using a catalyst system of the type implemented, for example, as described in the documents WO 2017093654, WO 2018020122 and WO 2018020123. Advantageously, the starting highly saturated diene elastomer is statistical and is preferentially prepared according to the semi-continuous or continuous method described in the documents WO 2017103543, WO 201713544, WO 2018193193 and WO 2018193194.

[0020] The rubber composition may contain, in addition to the functional highly saturated diene elastomer, a second diene elastomer. Diene elastomer is understood to mean an elastomer composed at least in part (i.e. homopolymer or copolymer) of diene monomer units (the monomers carrying two conjugated or non-conjugated carbon-carbon double bonds). The second elastomer may be selected from the group of highly unsaturated diene elastomers consisting of polybutadiene, polyisoprene, butadiene copolymers, isoprene copolymers and mixtures thereof. Highly unsaturated elastomer refers to an elastomer containing more than 50 mol% diene units.

[0021] Preferably, the content of the functional highly saturated diene elastomer in the rubber composition is at least 50 parts by mass per 100 parts of elastomer of the rubber composition (phr). More preferentially, the content of the functional highly saturated diene elastomer in the rubber composition varies in the range of 80 to 100 phr. Even more preferentially, the content varies in the range of 90 to 100 phr. The content is advantageously 100 phr. The functional highly saturated diene elastomer can be one functional highly saturated diene elastomer or a mixture of several functional highly saturated diene elastomers differing from each other in their microstructure or macrostructure. When the rubber composition comprises several functional highly saturated diene elastomers differing from each other in their microstructure or macrostructure, the content of the functional highly saturated diene elastomer in the rubber composition refers to a mixture of functional highly saturated diene elastomers.

[0022] The silica used may be any reinforcing silica known to those skilled in the art, in particular 450m 2 / g, preferably 30 to 400m 2 / g range, especially 60-300m 2 The specific surface area may be any precipitated or fumed silica having a BET specific surface area of ​​1000 nm / g and also a CTAB specific surface area of ​​1000 nm / g. In the present disclosure, the BET specific surface area is measured by gas adsorption using the Brunauer-Emmett-Teller method described in “The Journal of the American Chemical Society”, (Vol. 60, page 309, February 1938), more specifically according to the method adopted in the standard NF ISO 5794-1, Annex E of June 2010 [multipoint (5-point) volumetric method - gas: nitrogen - degassed under vacuum: 160°C for 1 hour - relative pressure p / p0 range: 0.05 to 0.17]. The CTAB specific surface area values ​​were measured according to the standard NF ISO 5794-1, Annex G of June 2010. The method is based on the adsorption of CTAB (N-hexadecyl-N,N,N-trimethylammonium bromide) on the “outer” surface of the reinforcing filler.

[0023] All kinds of precipitated silicas can be used, especially highly dispersible silicas (HDS). These precipitated silicas, whether highly dispersible or not, are well known to those skilled in the art. For example, mention can be made of the silicas described in patent applications WO 03 / 016215 and WO 03 / 016387. Among the commercially available HDS silicas, in particular the Ultrasil® 5000GR and Ultrasil® 7000GR silicas from Evonik or the Zeosil® 1085GR, Zeosil® 1115 MP, Zeosil® 1165MP, Zeosil® Premium 200MP and Zeosil® HRS 1200 MP silicas from Solvay can be used. As non-HDS silicas the following commercially available silicas can be used: Ultrasil® VN2GR and Ultrasil® VN3GR silicas from Evonik, Zeosil® 175GR silica from Solvay or Hi-Sil EZ120G(-D), Hi-Sil EZ160G(-D), Hi-Sil EZ200G(-D), Hi-Sil 243LD, Hi-Sil 210 and Hi-Sil HDP320G silicas from PPG.

[0024] The reinforcing filler can include any kind of "reinforcing" filler other than silica, such as carbon black, known for its ability to reinforce rubber compositions that can be used in particular in the manufacture of tires. Suitable carbon blacks include all carbon blacks, in particular black pigments conventionally used in tires or their treads. Among said carbon blacks, more specifically mention is made of the reinforcing carbon blacks of the 100, 200 and 300 series, or the black pigments of the 500, 600 or 700 series (ASTM D-1765-2017 grades), such as N115, N134, N234, N326, N330, N339, N347, N375, N550, N683 and N772 black pigments. These carbon blacks can be used in isolated form, as commercially available, or in any other form, for example as a support for some rubber additives used. When carbon black is used in the rubber composition, it is preferably present in a content of less than or equal to 10 phr (for example, the carbon black content may be in the range of 1 to 10 phr). Advantageously, the carbon black content in the rubber composition is less than or equal to 5 phr. Within the indicated interval, the chromogenic (black colorant) and UV stabilizing properties of carbon black are beneficial and do not further adversely affect the typical performance qualities provided by silica. Silica preferentially represents more than 50% by weight of the reinforcing filler, in other words the proportion of silica in the reinforcing filler is greater than 50% by weight compared to the total weight of the reinforcing filler, and more preferentially silica represents more than 85% by weight of the reinforcing filler.

[0025] The total content of reinforcing fillers can vary over a wide range, for example from 30 phr to 150 phr. According to a first embodiment, the total content of reinforcing fillers varies within the range of 30 phr to 60 phr. According to a second embodiment, the total content of reinforcing fillers varies within the range of more than 60 phr to 150 phr. For use of the rubber composition in treads with very low rolling resistance, the first embodiment is preferred over the second embodiment. Any one of these ranges of the total content of reinforcing fillers can be applied to any one of the embodiments of the present invention. To couple the silica to the functional highly saturated diene elastomer, a coupling agent (or binder), a silane that is at least difunctional, is used to ensure a sufficient correlation of chemical and / or physical properties between the silica and the diene elastomer. The rubber composition according to the invention comprises as coupling agent an organofunctional silane containing at least one blocked mercaptosilane unit, at least one mercaptosilane unit and at least one functional group which is a hydroxyalkoxysilyl group or a cyclic dialkoxysilyl group. The organofunctional silane corresponds to the following formula (1): (A) p (B) q (1) (In the formula, -A is a symbol representing a blocked mercaptosilane unit corresponding to formula (2),

[0026] [ka] -B is a symbol representing a mercaptosilane unit corresponding to formula (3). [ka] In formula (2), R3 is a hydrogen atom, a linear or branched C1-C 18 Alkyl, linear or branched C2-C 18 alkenyl.

[0027] In formulas (2) and (3), each R4 is independently selected from a linear or branched C1-C6 saturated hydrocarbon-based divalent group, and each Z forms a bridge structure between a silicon atom of one unit and a silicon atom of another unit. b may be the same or different, (-O-) 0.5 and [-O(R 0 CR 0 ) f O-] 0.5 are independently selected from the symbol R 0 may be the same or different, each represents a hydrogen atom or a C1-C3 alkyl, f is a number within the range of 2 to 15, and each Z c is the formula [-O(R 0 CR 0 ) f O-] 0.5 is a group of R 0 and f are as defined above, and each X is a hydrogen atom, a hydroxyl group, a C1-C6 alkyl group, a C1-C6 alkoxy group, or a group of formula HO(R 0 CR 0 ) f R is independently selected from the group consisting of O-, 0 and f is as defined above, and u+v+2w=3, where u is a number equal to 0, 1, 2 or 3, v is a number equal to 1, 2 or 3, and w is a number equal to 0 or 1.

[0028] p is a number within the range of 1 to 20, and q is a number within the range of 1 to 20. For purposes of this invention, the term "organofunctional silane" refers to a silane or mixture of silanes characterized in that it has at least one blocked, i.e., protected, thiol functional group, one unprotected thiol functional group, and at least one functional group which is a hydroxyalkoxysilyl group or a cyclic dialkoxysilyl group. The term "mercaptosilane unit" means a unit that contains at least one silicon atom bonded to a carbon atom and a thiol functional group (-SH). The term "blocked mercaptosilane unit" refers to a unit containing at least one silicon atom and at least one blocked thiol functional group. The blocked thiol functional group can be, for example, a thioester group -S-(CO)-R. In the compound of formula (1), the order of the blocked mercaptosilane repeating units (A) and the mercaptosilane repeating units (B) is random. In particular, this order can be alternating (e.g., ABABAB), block (e.g., AAABBB) or statistical, i.e., the sequential distribution of the units (A) and (B) follows known statistical laws. The term "hydroxyalkoxy group" as used in the name hydroxyalkoxysilyl refers to a group of the formula HO(R 0 CR 0 ) f R represents a monovalent group of O- 0 and f is as defined above.

[0029] The term "cyclic dialkoxysilyl group" refers to a group in which a silicon atom is bonded to two oxygen atoms that are each bonded to different carbon atoms of the same alkylene group. The term "bridged structure" refers to a chemical structure made of a covalent bond that allows the connection of two repeating units, which may be identical or different. Group C n -C m refers to the number of carbon atoms making up a group containing n to m carbon atoms, where n and m are integers with m being greater than n. Preferably, R3 in formula (2) is a hydrogen atom, C1-C 10 Alkyl and C2-C 10 alkenyl. In a more preferred manner, R3 in formula (2) is a straight chain C6-C8 alkyl. In an even more preferred manner, the symbol R3 in formula (2) is heptyl (C7H 15 -). Preferably, each R4 in formulae (2) and (3) is independently a linear C1-C4 alkylene. More preferably, each R4 is propylene. Preferably, each Z in formulas (2) and (3) b is the formula (-O-) 0.5 , [-OCH2CH2CH2O-] 0.5 , [-OCH2CH2CH2CH2O-] 0.5 and [-OCH2CH(CH3)CH2O-] 0.5 More preferentially, Z in formula (2) and (3) is independently selected from the group consisting of: b is the formula (-O-) 0.5 or the formula [-OCH2CH(CH3)CH2O-] 0.5 has.

[0030] Preferably, each Z in formulas (2) and (3) c has the formula [-OCH2CH2CH2O-] 0.5 , [-OCH2CH2CH2CH2O-] 0.5 and [-OCH2CH(CH3)CH2O-] 0.5 More preferentially, each Z in formula (2) and (3) is independently selected from the group consisting of: c has the formula [-OCH2CH(CH3)CH2O-] 0.5 It is. Preferably, each X in formula (2) and (3) is independently selected from the group consisting of hydroxyl, methoxy, ethoxy, methyl, ethyl, 3-hydroxypropoxy, 3-hydroxy-2-methylpropoxy and 4-hydroxybut-1-oxy. More preferentially, each X in formula (2) and (3) is the same and is selected from the group consisting of hydroxyl, methoxy, ethoxy and 3-hydroxy-2-methylpropoxy. Highly advantageously, in formulas (2) and (3), R3 is heptyl (CH 15 -), each R4 is propylene, and each Z b is the formula (-O-) 0.5 or [-OCH2CH(CH3)CH2O-] 0.5 And each Z c has the formula [-OCH2CH(CH3)CH2O-] 0.5wherein each X is selected from the group consisting of hydroxyl, methoxy, ethoxy, and 3-hydroxy-2-methylpropoxy; and u+v+2w=3, where u is 0, 1, 2, or 3; v is 1, 2, or 3; and w is 0 or 1.

[0031] Notation (-O-) 0.5 and [-O(R 0 CR 0 ) f O-] 0.5 refers to half of the siloxane bonds and half of the bridging dialkoxy groups, respectively. These notations are used in conjunction with the silicon atoms of the repeating units of the oligomer. The notations indicate half of the oxygen atoms, i.e., half of the oxygen atoms bonded to the silicon atoms of the repeating unit, or half of the dialkoxy groups, i.e., half of the dialkoxy group atoms bonded to the silicon atoms of the repeating unit, with the understanding that the other half of the oxygen atoms or dialkoxy groups, respectively, are bonded to other silicon atoms of other repeating units of the oligomer structure, which may be the same or different. Thus, (-O-) 0.5 forms a siloxane bond between two silicon atoms belonging to each repeating unit. [-O(R 0 CR 0 ) f O-] 0.5 is a bridge structure between two silicon atoms belonging to each repeating unit (this intermolecular structure is Z b or [-O(R 0 CR 0 ) f O-] 0.5 A ring structure of two oxygen atoms (this intramolecular structure is Z c A person skilled in the art will understand that in the compound of formula (1), the bridge structures may be the same or different between the repeating units. For example, the bridge structure may be -Si-O(R 0 CR 0 ) f Type of O-Si- or -Si-O(R 0 CR 0 ) fIt may be a mixture of -O-Si- and -Si-O-Si- bridged structures.

[0032] Preferentially, the organofunctional silane has a molar percentage of blocked mercaptosilane units (A) in the range of 20% to 80% and a molar percentage of mercaptosilane units (B) in the range of 80% to 20%. More preferentially, the organofunctional silane has a molar percentage of blocked mercaptosilane units (A) in the range of 40% to 60% and a molar percentage of mercaptosilane units (B) in the range of 60% to 40%. Even more preferentially, the organofunctional silane has a molar percentage of blocked mercaptosilane units in the range of 50% to 55% and a molar percentage of mercaptosilane units in the range of 50% to 45%. The molar percentage of blocked mercaptosilane units and the molar percentage of mercaptosilane units in the organofunctional silane, whether blocked or not, are calculated relative to the total number of thiol units in the organofunctional silane and can be calculated by any method known to the person skilled in the art, for example 1 It can be measured via 1 H NMR analysis. The coupling agent, an organofunctional silane, can be obtained via a synthesis method comprising at least one step (a) of transesterifying a diol compound of formula (9) with at least one blocked mercaptosilane compound of formula (10) and at least one mercaptosilane compound of formula (11). HO(R 0 CR 0 ) f OH (9) (RO)3SiR4SC(=O)R3(10) (RO)3SiR4SH (11) (In the formula, R 0 and f is as defined above, i.e., R 0 may be the same or different and represent a hydrogen atom, methyl, ethyl, or propyl; f is a number ranging from 2 to 15; R may be the same or different and represents a linear C1-C6 alkyl group; R and R are as defined above, i.e. R represents a linear or branched, saturated divalent C1-C6 hydrocarbon-based group; R is a hydrogen atom, a linear or branched C1-C 18 Alkyl or linear or branched C2-C 18 (representing alkenyl)

[0033] The transesterification reaction is a reaction well known to those skilled in the art and may be carried out in the presence of a transesterification catalyst, such as a strong acid.

[0034] Preferentially, in the above-mentioned method, the diol compound of formula (9) is selected from HOCH2CH2CH2OH, HOCH2CH2CH2CH2OH and HOCH2CH(CH3)CH2OH. More preferentially, in the above-mentioned method, the diol compound of formula (4) is HOCH2CH(CH3)CH2OH. Preferentially, the compounds of formula (10) and (11) used in carrying out the abovementioned process are those in which the radical R is selected from methyl, ethyl, propyl, isopropyl, n-butyl and isobutyl. Preferentially, the compound of formula (10) used in the implementation of the above-mentioned method is one in which R3 is a hydrogen atom, a linear or branched C1-C 10 Alkyl, or linear or branched C2-C 10 More preferentially, the compound of formula (10) used in the above-mentioned method is one in which R3 is a linear C6-C8 alkyl. Even more preferentially, the compound of formula (10) used in the above-mentioned method is one in which R3 is a heptyl (C7H 15 -). Preferably, the compounds of formulae (10) and (11) used in carrying out the above-mentioned method are those in which each R4 is independently a divalent hydrocarbon-based radical selected from the group consisting of linear C1-C4 alkylenes. More preferentially, the compounds of formulae (10) and (11) used in carrying out the above-mentioned method are those in which each R4 is propylene.

[0035] Preferentially, the compounds of formula (10) and (11) used in the implementation of the above-mentioned process are those in which R3 is heptyl, R4 is propylene, R may be identical or different (preferably identical) and are selected from methyl, ethyl, propyl, isopropyl, n-butyl and isobutyl, and the compound of formula (9) used in the implementation of the above-mentioned process is HOCH2CH(CH3)CH2OH. The mixture of compounds of formula (10) and the mixture of compounds of formula (11) can be used to synthesize organofunctional silane coupling agents. The method for synthesizing the coupling agent includes - at least one step (b) of treating the product obtained in step (a) to convert some blocked thiol functions, if any, present in the product obtained in step (a) into thiol (-SH) functions, and / or - at least one step (c) of treating the product obtained in step (a) to convert some of the thiol functions, if any, present in the product obtained in step (a) into blocked thiol functions, and / or at least one step (d) of partial hydrolysis of the product obtained in step (a), if step (b) is carried out in the process, and of the product obtained in step (b), if step (c) is carried out in the process, It may also include.

[0036] Treatment step (b) may be, for example, a step of converting the blocked thiol functions carried by the product obtained in step (a) into thiol functions using a strong base, for example NaOEt. Treatment step (c) may be, for example, a step of converting a carboxylic acid (in particular CH 15 COOH) or acyl chloride (especially CH 15The partial hydrolysis step (d) may be carried out in the presence of excess water relative to the product and reagents used in step (a) and, if present, optionally in steps (b) and (c). The partial hydrolysis step may be carried out in the presence of excess water relative to the product and reagents used in step (a) and, if present, optionally in steps (b) and (c). b (-O-) 0.5 or OH. The skilled person may in particular refer to document WO 2007 / 098120, which describes a method for producing organofunctional silane coupling agents. The organofunctional coupling agent can be obtained in the form of a mixture resulting from the implementation of the above-mentioned method and can be used in the form of this mixture in the rubber composition according to the invention, which mixture contains not only the organofunctional coupling agent but also other silanes selected from any one of the following compounds and their mixtures: - a compound of formula (2') derived from formula (2), which is represented by the formula (2') b v But, Z a t is replaced by Z a has the same definition as the group X in formula (2), t is a number equal to 0, 1, 2 or 3, and u+t+2w=3, with u and w having the same definition as in formula (2), - a compound of formula (3') derived from formula (3), which is represented by the formula (3') b v But, Z a t is replaced by Z a has the same definition as the group X in formula (3), t is a number equal to 0, 1, 2 or 3, and u+t+2w=3, with u and w having the same definition as in formula (3), - a dimer consisting of two blocked mercaptosilane units of formula (2), - a dimer consisting of two mercaptosilane units of formula (3), - a dimer consisting of a blocked mercaptosilane unit (2) and a mercaptosilane unit of formula (3), - oligomers consisting of blocked mercaptosilane units of formula (2), - oligomers consisting of mercaptosilane units of formula (3):

[0037] Organofunctional silane coupling agents are commercially available, for example, from Momentive under the trade name "NXT-Z", particularly "NXT-Z45". In the rubber composition according to the invention, the content of the organofunctional silane coupling agent is adjusted by the person skilled in the art according to the specific surface area of ​​the silica used in the rubber composition and according to the silica content in the rubber composition, which is preferentially in the range of 1 to 15 phr, more preferentially 1.5 to 10 phr, even more preferentially 2 to 5 phr. Another essential feature of the rubber composition according to the invention is that it contains a vulcanization system, i.e. a sulfur-based crosslinking system. The sulfur is generally provided in the form of molecular sulfur or sulfur donors, preferably in molecular form. Sulfur in molecular form is also called molecular sulfur. The term "sulfur donor" means any compound that releases sulfur atoms that may combine in the form of polysulfide chains that can be inserted into the polysulfide chains formed during vulcanization and crosslinked to elastomer chains. Various known secondary vulcanization accelerators or vulcanization activators, such as zinc oxide, stearic acid, guanidine derivatives (especially diphenylguanidine), etc., are added to the vulcanization system that is incorporated during the first non-production stage and / or during the productive stage. The sulfur content is preferably between 0.5 and 4 phr, and the content of the primary accelerator is preferably between 0.5 and 5 phr. These preferential contents may be applied to any one of the embodiments of the present invention.

[0038] As vulcanization accelerators (primary or secondary), any compound capable of acting as an accelerator of the vulcanization of diene elastomers in the presence of sulfur can be used, in particular accelerators of the thiazole type and also of its derivatives, accelerators of the sulfenamide type for the primary accelerators, or accelerators of the thiuram, dithiocarbamate, dithiophosphate, thiourea and xanthate type for the secondary accelerators. As examples of primary accelerators, mention may be made in particular of sulfenamide compounds, such as N-cyclohexyl-2-benzothiazylsulfenamide ("CBS"), N,N-dicyclohexyl-2-benzothiazylsulfenamide ("DCBS"), N-tert-butyl-2-benzothiazylsulfenamide ("TBBS"), and mixtures of these compounds. The primary accelerators are preferentially sulfenamides, more preferentially N-cyclohexyl-2-benzothiazylsulfenamides. As examples of secondary accelerators, mention may be made in particular of thiuram disulfides, such as tetraethylthiuram disulfide, tetrabutylthiuram disulfide ("TBTD"), tetrabenzylthiuram disulfide ("TBZTD") and mixtures of these compounds. The secondary accelerator is preferentially a thiuram disulfide, more preferentially tetrabenzylthiuram disulfide. Vulcanization is carried out in known manner at temperatures generally ranging from 130° C. to 200° C. for a sufficient period of time which may range, for example, from 5 minutes to 90 minutes, depending in particular on the cure temperature of the vulcanization system employed and on the vulcanization kinetics of the composition under consideration.

[0039] The rubber composition according to the invention may also contain all or some of the conventional additives commonly used in elastomeric compositions intended for the manufacture of tires, in particular pigments, protective agents such as antiozonant waxes, chemical antiozonants, antioxidants, and plasticizers such as plasticizing oils or resins. The rubber composition can be prepared, prior to vulcanization, in a suitable mixer using two successive preparation stages according to procedures well known to those skilled in the art: a first stage of thermomechanical processing or mixing at high temperatures up to a maximum temperature of 110°C to 190°C, preferably 130°C to 180°C (sometimes called the "non-forming" stage), followed by a second stage of mechanical processing at lower temperatures, generally below 110°C, for example 40°C to 100°C (sometimes called the "forming" stage), during which the sulfur or sulfur donors and vulcanization accelerators are incorporated. By way of example, the first (non-productive) stage is carried out in one thermomechanical step during which all necessary components, optional auxiliary processing aids and various other additives, except the vulcanization system, are introduced into a suitable mixer, for example a conventional internal mixer. In this non-productive stage, the total time of mixing is preferably between 1 and 15 minutes. After the mixture thus obtained during the first non-productive stage has been cooled, the vulcanization system is then incorporated at low temperature, typically in an external mixer, for example an open mill, after which everything is mixed for a few minutes, for example between 2 and 15 minutes (productive stage).

[0040] The rubber composition may be calendered or extruded, in particular in the form of sheets or slabs for laboratory characterization, or also in the form of rubber semi-finished products (or profiled elements) that can be used in tires. The composition may be either in the raw state (before crosslinking or vulcanization) or in the cured state (before crosslinking or after vulcanization). The composition may consist of all or some of the semi-finished products intended for use in pneumatic or non-pneumatic tires, in particular with the tread, in particular in the tire tread. In summary, the present invention is advantageously carried out according to any one of the following embodiments 1 to 47. Embodiment 1: - A functional highly saturated diene elastomer which is a copolymer containing ethylene units and 1,3-diene units and carrying pendant groups containing N-substituted imidazole functional groups, wherein the ethylene units represent more than 50 mol % of the constituent repeat units of the functional highly saturated diene elastomer; - Vulcanization systems, - reinforcing fillers containing silica, as well as organofunctional silane coupling agents containing at least one blocked thiol functional group, at least one thiol functional group and at least one functional group which is a hydroxyalkoxysilyl group or a cyclic dialkoxysilyl group, said organofunctional silane coupling agents corresponding to formula (1) A rubber composition comprising: (A) p (B) q (1) (wherein A and B represent a blocked mercaptosilane unit corresponding to formula (2) and a mercaptosilane unit corresponding to formula (3), respectively.

[0041] [ka]

[0042] (In the formula, R3 is a hydrogen atom, a linear or branched C1-C 18 Alkyl, linear or branched C2-C 18 alkenyl, Each R4 is independently selected from a linear or branched, saturated C1-C6 divalent hydrocarbon-based group; Each Z unit may be the same or different, and forms a bridge structure between a silicon atom of one unit and a silicon atom of another unit. b is (-O-) 0.5 and [-O(R 0 CR 0 ) f O-] 0,5 are independently selected from the symbol R 0 may be the same or different and each represents a hydrogen atom or a C1-C3 alkyl; f is a number ranging from 2 to 15; Each Z unit forms a ring structure with a silicon atom c is the formula [-O(R 0 CR 0 ) f O-] 0.5 is a group of R 0 and f is as defined above, Each X is a hydrogen atom, a hydroxyl group, a C1-C6 alkyl group, a C1-C6 alkoxy group, or a group of the formula HO(R 0 CR 0 ) f R is independently selected from the group consisting of O-, 0 and f is as defined above, u+v+2w=3, where u is a number equal to 0, 1, 2 or 3, v is a number equal to 1, 2 or 3, and w is a number equal to 0 or 1; p is a number in the range of 1 to 20; q is a number in the range of 1 to 20)

[0043]

[0023] Embodiment 2: The rubber composition of embodiment 1, wherein the ethylene units in the functionalized highly saturated diene elastomer represent at least 60 mol % of the constituent repeat units of the functionalized highly saturated diene elastomer. Embodiment 3: A rubber composition according to any one of embodiments 1 and 2, wherein the ethylene units in the functional highly saturated diene elastomer represent at least 65 mol % of the constituent repeat units of the functional highly saturated diene elastomer. Embodiment 4: A rubber composition according to any one of embodiments 1 and 3, wherein the ethylene units in the functional highly saturated diene elastomer represent at least 70 mol % of the constituent repeat units of the functional highly saturated diene elastomer. Embodiment 5: The rubber composition according to any one of embodiments 1 to 4, wherein the ethylene units in the functional highly saturated diene elastomer represent up to 90 mol % of the constituent repeat units of the functional highly saturated diene elastomer.

[0044] Embodiment 6: The rubber composition according to any one of embodiments 1 to 5, wherein the ethylene units in the functional highly saturated diene elastomer represent up to 85 mol % of the constituent repeat units of the functional highly saturated diene elastomer. Embodiment 7: The rubber composition according to any one of embodiments 1 to 6, wherein the ethylene units in the functional highly saturated diene elastomer represent up to 80 mol % of the constituent repeat units of the functional highly saturated diene elastomer. Embodiment 8: The rubber composition according to any one of embodiments 1 to 7, wherein the N-substituted imidazole functional group is a group of formula (4).

[0045] [ka] (wherein, symbol Y1 represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, symbol Y2 represents a bond to a diene unit of a functional highly saturated diene elastomer, and symbols Y3 and Y4 each represent a hydrogen atom). Embodiment 9: The rubber composition of embodiment 8, wherein the alkyl represented by Y2 contains 1 to 3 carbon atoms. Embodiment 10: The rubber composition according to any one of embodiments 8 and 9, wherein the alkyl represented by Y1 is methyl. Embodiment 11: The rubber composition according to any one of embodiments 1 to 10, wherein the functional highly saturated diene elastomer is a copolymer of ethylene and a 1,3-diene modified by reacting a modifier containing a group reactive to diene units and containing an imidazole functional group of formula (5).

[0046] [ka] (wherein, symbol Z1 represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, symbol Z2 represents a bond to a reactive group, and symbols Z3 and Z4 each represent a hydrogen atom).

[0031] Embodiment 12: The rubber composition of embodiment 11, wherein the modifier is a 1,3-dipolar nitrile oxide, nitrone, or nitrile imine compound. Embodiment 13: A rubber composition according to any one of embodiments 11 and 12, wherein the modifier is a 1,3-dipole compound that is an aromatic nitrile monoxide, i.e., a compound that contains a benzene ring substituted with a nitrile oxide dipole and a group containing an imidazole functional group of formula (5).

[0047] [ka] (wherein the symbol Z1 represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, the symbol Z2 represents a bond to a dipole, and the symbols Z3 and Z4 each represent a hydrogen atom). Embodiment 14: The rubber composition according to any one of embodiments 12 and 13, wherein the 1,3-dipole compound contains units of formula (6).

[0048] [ka] (wherein R'1 represents a nitrile oxide dipole, one of the symbols R'2 to R'6 represents a saturated group having 1 to 6 carbon atoms and covalently bonded to one of the nitrogen atoms of the 5-membered ring of the imidazole functional group of formula (5), and the other symbols may be the same or different and represent a hydrogen atom or a substituent.)

[0031] Embodiment 15: The rubber composition of embodiment 14, wherein the saturated group is an alkanediyl.

[0041] Embodiment 16: The rubber composition according to any one of embodiments 14 and 15, wherein the saturated group is an alkanediyl having 1 to 3 carbon atoms.

[0049] Embodiment 17: The rubber composition according to any one of embodiments 14 to 16, wherein the saturated group is methanediyl. Embodiment 18: The rubber composition according to any one of embodiments 14 to 17, wherein the substituent is an alkyl group having 1 to 3 carbon atoms. Embodiment 19: The rubber composition according to any one of embodiments 14 to 18, wherein the substituent is methyl or ethyl. Embodiment 20: The rubber composition according to any one of embodiments 14 to 19, wherein R'2 and R'6 are different from a hydrogen atom. Embodiment 21: The rubber composition according to any one of embodiments 14 to 20, wherein R'2, R'4 and R'6 are the same and are different from hydrogen atoms. Embodiment 22: The rubber composition according to any one of embodiments 1 to 21, wherein the content of imidazole functional groups in the functional highly saturated diene elastomer is greater than 0 mol% and less than 3 mol% of the constituent repeating units of the functional highly saturated diene elastomer.

[0050] Embodiment 23: The rubber composition according to any one of embodiments 1 to 22, wherein the 1,3-diene is 1,3-butadiene or a mixture of 1,3-dienes, one of which is 1,3-butadiene. Embodiment 24: The rubber composition according to any one of embodiments 1 to 23, wherein the 1,3-diene is 1,3-butadiene.

[0041] Embodiment 25: The rubber composition according to any one of embodiments 1 to 24, wherein the functional highly saturated diene elastomer is a statistical copolymer. Embodiment 26: The rubber composition according to any one of embodiments 1 to 25, wherein the content of the functional highly saturated diene elastomer is at least 50 parts by weight per 100 parts elastomer (phr) of the rubber composition. Embodiment 27: The rubber composition according to any one of the embodiments 1 to 26, wherein the content of the functional highly saturated diene elastomer varies within the range of 80 to 100 phr.

[0051] Embodiment 28: The rubber composition according to any one of embodiments 1 to 27, wherein silica represents more than 50% by mass of the reinforcing filler. Embodiment 29: The rubber composition according to any one of embodiments 1 to 28, wherein silica represents more than 85% by mass of the reinforcing filler. Embodiment 30: The rubber composition according to any one of embodiments 1 to 29, wherein the total content of reinforcing fillers varies within the range of 30 to 150 phr. Embodiment 31: The rubber composition according to any one of embodiments 1 to 30, wherein the total content of reinforcing fillers varies within the range of 30 phr to 60 phr. Embodiment 32: R3 in formula (2) is a hydrogen atom, C1-C 10 Alkyl and C2-C 10 The rubber composition according to any one of embodiments 1 to 31, wherein the alkyl group is selected from the group consisting of aryl, aryl, and alkenyl. Embodiment 33: A rubber composition according to any one of embodiments 1 to 32, wherein R3 in formula (2) is a linear C6-C8 alkyl, more preferentially heptyl.

[0052] Embodiment 34: The rubber composition according to any one of embodiments 1 to 33, wherein each R4 in formulas (2) and (3) is independently a linear C1-C4 alkylene. Embodiment 35: The rubber composition according to any one of embodiments 1 to 34, wherein each R4 in formulas (2) and (3) is propylene. Embodiment 36: Each Z in formula (2) and (3) b But the formula (-O-) 0.5 , [-OCH2CH2CH2O-] 0.5 , [-OCH2CH2CH2CH2O-] 0.5 and [-OCH2CH(CH3)CH2O-] 0.5 36. The rubber composition according to any one of embodiments 1 to 35, wherein the units are independently selected from the group consisting of: Embodiment 37: Each Z in formulas (2) and (3) b But the formula (-O-) 0.5 or [-OCH2CH(CH3)CH2O-] 0.5 The rubber composition according to any one of embodiments 1 to 36, Embodiment 38: Each Z in formula (2) and (3) c has the formula [-OCH2CH2CH2O-] 0.5 , [-OCH2CH2CH2CH2O-] 0.5 and [-OCH2CH(CH3)CH2O-] 0.5 38. The rubber composition of any one of embodiments 1 to 37, wherein the units are independently selected from the group consisting of: Embodiment 39: Each Z in formulas (2) and (3) c has the formula [-OCH2CH(CH3)CH2O-] 0.5 The rubber composition according to any one of embodiments 1 to 38, wherein

[0053] Embodiment 40: The rubber composition of any one of embodiments 1 to 39, wherein each X in formulas (2) and (3) is independently selected from the group consisting of hydroxyl, methoxy, ethoxy, methyl, ethyl, 3-hydroxypropoxy, 3-hydroxy-2-methylpropoxy, and 4-hydroxybut-1-oxy. Embodiment 41: The rubber composition according to any one of embodiments 1 to 40, wherein each X in formulas (2) and (3) is the same and is selected from the group consisting of hydroxyl, methoxy, ethoxy, and 3-hydroxy-2-methylpropoxy. Embodiment 42: The rubber composition according to any one of embodiments 1 to 41, wherein the organofunctional silane has a mole percentage of blocked mercaptosilane units (A) in the range of 20% to 80% and a mole percentage of mercaptosilane units (B) in the range of 80% to 20%. Embodiment 43: The rubber composition according to any one of embodiments 1 to 42, wherein the organofunctional silane has a mole percentage of blocked mercaptosilane units (A) in the range of 40% to 60% and a mole percentage of mercaptosilane units (B) in the range of 60% to 40%. Embodiment 44: The rubber composition according to any one of embodiments 1 to 43, wherein the organofunctional silane has a mole percentage of blocked mercaptosilane units in the range of 50% to 55% and a mole percentage of mercaptosilane units in the range of 50% to 45%.

[0054] Embodiment 45: The rubber composition according to any one of embodiments 1 to 44, wherein the content of the organofunctional silane coupling agent ranges from 1 to 15 phr. Embodiment 46: A rubber composition according to any one of the embodiments 1 to 45, wherein the content of organofunctional silane coupling agent ranges from 1.5 to 10 phr, preferentially from 2 to 5 phr. Embodiment 47: A tire comprising, preferentially in its tread, a rubber composition as defined in any one of the embodiments 1 to 46. The above mentioned, and other, features of the invention will be better understood on reading the following description of some exemplary embodiments of the invention, given by way of non-limiting example. EXAMPLES

[0055] Properties at break: The tensile test makes it possible to determine the properties at break. Unless otherwise stated, this test is carried out according to French standard NF T 46-002 of September 1988, with type H2 specimens and a pulling speed of 500 mm / min. The tensile strength (in MPa) and the elongation at break (in %) are measured at 60 °C ± 2 °C and also at 100 °C ± 2 °C according to standard NF T 46-002. Results are expressed relative to the control, with a standard deviation of 100. Values ​​greater than the control value, arbitrarily set at 100, indicate an improved result, i.e., the measured amount is greater than the control amount. Elastomer microstructure by Nuclear Magnetic Resonance (NMR) analysis: The microstructure of the elastomer is 1 If the resolution of the H NMR spectrum does not allow for the assignment and quantification of all species, 13 Combined with C NMR analysis, 1 Determined by H NMR analysis. The measurements are carried out using a Bruker 500 MHz NMR spectrometer at frequencies of 500.43 MHz for proton observation and 125.83 MHz for carbon observation. For insoluble elastomers capable of swelling in the solvent, a 4 mm z-grade HRMAS probe was used in proton decoupling mode for proton and carbon observations. Spectra are acquired at spinning rates of 4000 Hz to 5000 Hz.

[0056] For measurements on soluble elastomers, a liquid NMR probe was used in proton decoupling mode for proton and carbon monitoring. An insoluble sample is prepared in a rotor filled with the material to be analyzed and a deuterated solvent that allows expansion, typically deuterated chloroform (CDCl3). The solvent used must always be deuterated and its chemistry can be adapted by the skilled artisan. The amount of material used is adjusted to obtain a spectrum of sufficient sensitivity and resolution. Soluble samples are dissolved in a deuterated solvent (approximately 25 mg of elastomer in 1 ml), typically deuterated chloroform (CDCl3). The solvent or solvent blend used must always be deuterated, and its chemistry can be adapted by the skilled artisan. In both cases (soluble or swollen samples): For proton NMR, a 30° single pulse sequence is used. The spectral window is set to observe all resonance lines belonging to the molecule being analyzed. The number of accumulations is set to obtain a signal-to-noise ratio sufficient for quantification of each unit. The repetition wait time between each pulse is adapted to obtain a quantitative measurement. For carbon NMR, a 30° single pulse sequence with only proton decoupling is used to avoid the Nuclear Overhauser Effect (NOE) during acquisition and maintain quantitation. The spectral window is set to observe all resonance lines belonging to the molecule being analyzed. The number of accumulations is set to obtain a signal-to-noise ratio sufficient for quantification of each unit. The repetition wait time between each pulse is adapted to obtain a quantitative measurement.

[0057] The NMR measurements are carried out at 25°C. Glass Transition Temperature of Polymer: The glass transition temperature (Tg) is measured by differential scanning calorimetry according to standard ASTM D3418 (1999). Mooney Viscosity: Mooney viscosity is measured using a vibrating consistometer according to standard ASTM D1646 (1999). The measurement is carried out according to the following principle: the sample to be analyzed in the uncured state (i.e. before curing) is cast (formed) in a cylindrical chamber heated to a given temperature (100° C.). After 1 minute of preheating, the rotor rotates in the test specimen at 2 revolutions per minute and the working torque to maintain this movement is measured after 4 minutes of rotation. Mooney viscosity (ML) is expressed in "Mooney units" (MU, 1 MU = 0.83 Newton meters). Preparation of the starting highly saturated diene elastomer, E1: Elastomer E1 is a highly saturated diene elastomer, which is a copolymer of ethylene and 1,3-butadiene, and is prepared according to the following procedure.

[0058] A solution of butyloctylmagnesium (BOMAG) in methylcyclohexane and the catalyst system are added to a 70 L reactor containing methylcyclohexane (64 L), ethylene (5600 g) and 1,3-butadiene (2948 g). The Mg / Nd ratio is 6.2. The volume of the catalyst system solution introduced is 840 ml and the concentration of the catalyst system solution in Nd is 0.0065 M. The reaction temperature is controlled at a temperature of 80° C. and the polymerization reaction is started. The polymerization reaction occurs at a constant pressure of 8.3 bar. Throughout the polymerization, the reactor is fed with ethylene and 1,3-butadiene in a molar ratio of 73 / 27. The polymerization reaction is stopped by cooling the reactor, degassing and adding ethanol. An antioxidant is added to the polymer solution. After steam stripping and drying to constant weight, the copolymer is recovered. The polymerization time is 225 min. The weighed mass (6.206 kg) allows to measure the average catalytic activity of the catalytic system, expressed in kilograms of polymer synthesized per mole of neodymium metal and per hour (kg / mol.h). The copolymer has an ML value equal to 62. The catalyst system is a preformed catalyst system. The catalyst system is prepared from the metallocene at 0.0065 mol / l, [Me2Si(Flu)2Nd(μ-BH4)2Li(THF)], the cocatalyst BOMAG at a molar ratio BOMAG / Nd equal to 2.2, and the preformed monomer 1,3-butadiene at a molar ratio 1,3-butadiene / Nd equal to 90 in methylcyclohexane. The medium is heated at 80° C. for a period of 5 hours. The catalyst system is prepared according to the preparation method according to section II.1 of patent application WO2017093654.

[0059] Preparation of rubber composition: The 1,3-dipole compound 2,4,6-trimethyl-3-((2-methyl-1H-imidazol-1-yl)methyl)benzonitrile oxide is used as a modifier, the synthesis of which is described in patent application WO2015059274. The starting highly saturated diene elastomer used is elastomer E1. Four rubber compositions are prepared, which are manufactured in the following manner: The starting highly saturated diene elastomer E1, the modifiers mixed alone with the elastomer at 120°C for about 1 minute, then the various other components, except for silica, silane coupling agent and vulcanization system, are introduced into a 400 ml internal mixer at an initial tank temperature of about 80°C (final degree of filling: about 70% by volume). Then, the thermomechanical processing (non-production stage) is carried out in one step, lasting about 5 to 6 minutes at an average pallet speed of 100 rpm, until a maximum "drop-off" temperature of 160°C is reached. The mixture thus obtained is collected and cooled, after which the sulfur and sulfenamide type accelerators are placed in a mixer (homofinisher) at 23°C and everything is mixed for 5 minutes (production stage).

[0060] All rubber compositions contain a functional highly saturated diene elastomer according to the invention, a vulcanization system, silica and a silane coupling agent. Only rubber compositions C1 and C2 are according to the invention, since the silane coupling agent is an organofunctional silane of formula (1) according to the invention, "NXT-Z45" sold by Momentive. Compositions T1 and T2 differ from compositions C1 and C2, respectively, in that the coupling agent is bis(3-triethoxysilylpropyl)tetrasulfide having the formula [(C2H5O)3Si(CH2)3S2]2, abbreviated as TESPT, a polysulfide silane sold by Evonik under the trade name "Si69". In the case of rubber compositions T1 and T2, the total sulfur content is the same for the rubber compositions compared to each other, i.e. 0.3 phr, bearing in mind that the coupling agent "Si69" releases free sulfur during reaction with the elastomer and represents a source of sulfur available for vulcanization. The rubber composition formulations (in phr) are set forth in Table 1.

[0061] The compositions thus obtained are subsequently calendered either in the form of rubber slabs (thickness range 2-3 mm) or thin sheets for the measurement of their physical or mechanical properties after vulcanization at 150° C. (cured state) or in the form of profiled elements which, after cutting to the desired size and / or assembly, can be used directly as semi-finished products, for example for tires. The results of the properties of the rubber compositions in the cured state are given in Table 2. Table 2 shows that the elongation at break of rubber compositions C1 and C2 is significantly increased compared to their respective control compositions, T1 and T2, at both 60° C. and 100° C. This result is obtained without reducing the stress at break. Thus, the rubber compositions according to the invention show a strong improvement in properties at break.

[0062] [Table 1] (1) A copolymer of ethylene and 1,3-butadiene containing 74 mol % ethylene units, 19 mol % butadiene units in the form of 1.2 and 1.4 units and 7 mol % 1,2-cyclohexanediyl units and having a Tg of -44°C. (2) "Zeosil 1165 MP" from Solvay-Rhodia, microbead morphology (3) "Si69" Triethoxysilylpropyltetrasulfide (TESPT) liquid silane from Evonik (4) Silane mercapto-thiocarboxylate oligomer ("NXT-Z45") - CAS 922519-17-3 - Momentive (5) 1,3-dipole compound (2,4,6-trimethyl-3-((2-methyl-1H-imidazol-1-yl)methyl)benzonitrile oxide) (6) "Perkacit DPG" diphenyl guanidine from Flexsys (7) Anti-Ozone Wax from Sasol Wax, Varazon 4959 (8) N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine, Santoflex 6PPD from Flexys (9) Stearic Acid from Uniqema, Pristerene 4931 (10) Zinc oxide, technical grade, from Umicore (11) N-Cyclohexyl-2-benzothiazole sulfenamide, Santocure CBS from Flexsys.

[0063] [Table 2]

Claims

1. a functional highly saturated diene elastomer which is a copolymer containing ethylene units and 1,3-diene units and carrying pendant groups containing N-substituted imidazole functional groups, said ethylene units representing greater than 50 mol % of the constituent repeat units of said functional highly saturated diene elastomer; Vulcanization system, a reinforcing filler containing silica; and an organofunctional silane coupling agent comprising at least one blocked thiol functional group, at least one thiol functional group, and at least one functional group which is a hydroxyalkoxysilyl group or a cyclic dialkoxysilyl group, the organofunctional silane coupling agent corresponding to formula (1) A rubber composition comprising: (A) p (B) q (1) (wherein A and B represent a blocked mercaptosilane unit corresponding to formula (2) and a mercaptosilane unit corresponding to formula (3), respectively. 【Chemistry 1】 (In the formula, R 3 is a hydrogen atom, a straight-chain or branched C 1 -C 18 Alkyl, linear or branched C 2 -C 18 alkenyl, Each R 4 is a linear or branched saturated C 1 -C 6 are independently selected from divalent hydrocarbon-based groups; Each Z unit may be the same or different, and forms a bridge structure between a silicon atom of one unit and a silicon atom of another unit. b is (-O-) 0.5 and [-O(R 0 CR 0 ) f O-] 0,5 and the symbol R 0 may be the same or different, and each represents a hydrogen atom or C 1 -C 3 alkyl, and f is a number ranging from 2 to 15; Each Z unit forming a ring structure with the silicon atom c is represented by the formula [-O(R 0 CR 0 ) f O-] 0.5 is a group of R 0 and f is as defined above; Each X is a hydrogen atom, a hydroxyl group, C 1 -C 6 Alkyl group, C 1 -C 6 Alkoxy groups and groups of the formula HO(R 0 CR 0 ) f O— groups, and R 0 and f is as defined above; u+v+2w=3, where u is a number equal to 0, 1, 2 or 3, v is a number equal to 1, 2 or 3, and w is a number equal to 0 or 1; p is a number ranging from 1 to 20; q is a number in the range of 1 to 20

2. The rubber composition of claim 1, wherein the N-substituted imidazole functional group is a group of formula (4). 【Chemistry 2】 (wherein the symbol Y 1 represents a hydrogen atom or an alkyl having 1 to 6 carbon atoms, and the symbol Y 2 represents a bond to a diene unit of the functional highly saturated diene elastomer, and the symbol Y 3 and Y 4 are hydrogen atoms)

3. 2. The rubber composition of claim 1, wherein the 1,3-diene is 1,3-butadiene or a mixture of 1,3-dienes, one of which is 1,3-butadiene.

4. The rubber composition of claim 1 , wherein the functional highly saturated diene elastomer is a statistical copolymer.

5. The rubber composition of claim 1 , wherein silica represents greater than 50% by weight of the reinforcing filler.

6. R in formula (2) 3 is a hydrogen atom, C 1 -C 10 Alkyl and C 2 -C 10 The rubber composition of claim 1, wherein the alkyl group is selected from the group consisting of alkynyl and alkynyl.

7. Each R in formulas (2) and (3) 4 However, independently, linear C 1 -C 4 The rubber composition according to claim 1, wherein the alkylene is alkylene.

8. Each Z in formulas (2) and (3) b is the formula (-O-) 0.5 , [-OCH 2 CH 2 CH 2 O-] 0.5 , [-OCH 2 CH 2 CH 2 CH 2 O-] 0.5 and [-OCH 2 CH (CH 3 ) CH 2 O-] 0.5 2. The rubber composition of claim 1, wherein the units are independently selected from the group consisting of:

9. Each Z in formulas (2) and (3) c is represented by the formula [-OCH 2 CH 2 CH 2 O-] 0.5 , [-OCH 2 CH 2 CH 2 CH 2 O-] 0.5 and [-OCH 2 CH (CH 3 ) CH 2 O-] 0.5 2. The rubber composition of claim 1, wherein the units are independently selected from the group consisting of:

10. 2. The rubber composition according to claim 1, wherein each X in formulas (2) and (3) is independently selected from the group consisting of hydroxyl, methoxy, ethoxy, methyl, ethyl, 3-hydroxypropoxy, 3-hydroxy-2-methylpropoxy, and 4-hydroxybut-1-oxy.

11. 2. The rubber composition of claim 1, wherein the organofunctional silane has a mole percent of blocked mercaptosilane units (A) in the range of 20% to 80% and a mole percent of mercaptosilane units (B) in the range of 80% to 20%.

12. A tire comprising a rubber composition defined in any one of claims 1 to 11.

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