Rubber composition

Abstract

The present invention relates to a rubber composition comprising a highly saturated diene elastomer, which is a copolymer of ethylene and 1,3-diene, with ethylene units accounting for more than 50 mol % of the monomer units of the copolymer, a vulcanization system, a reinforcing filler containing silica, and an organofunctional silane coupling agent having 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, such a composition provides improved rupture properties in the cured state.

Description

[Technical field]

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

[0002] Rubber compositions reinforced with silica and comprising highly saturated diene elastomers are known from WO 2014 / 114607 and WO 2018 / 224776. Highly saturated diene elastomers are copolymers of ethylene and 1,3-diene, such as 1,3-butadiene, with the distinctive feature of containing more than 50 mol% of ethylene units. Due to their high ethylene content and low diene unit content of less than 50 mol%, they are generally very different from diene elastomers conventionally used in rubber compositions containing more than 50 mol% of diene units, such as polybutadiene, polyisoprene, and copolymers of 1,3-butadiene or isoprene with styrene. In particular, they have the distinctive feature of providing the rubber composition with a different property compromise between stiffness and hysteresis. There remains a need to further improve the rupture properties of such rubber compositions in the cured state. Summary of the Invention

[0003] The present inventors have discovered a novel rubber composition which has improved break properties in the cured state, such as elongation at break and stress at break. Thus, the present invention provides - highly saturated diene elastomers which are copolymers of ethylene and 1,3-diene, the ethylene units representing more than 50 mol % of the monomer units of the copolymer; - Vulcanization system, - reinforcing fillers containing silica, and an organofunctional silane coupling agent 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, and corresponding to formula (1) (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] During the ceremony, R 3 is a hydrogen atom, a linear 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 b forms a bridge structure between a silicon atom of one unit and a silicon atom of another unit (the units may be the same or different), forming (-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 C 1 -C 3 alkyl, and f is a number ranging from 2 to 15; each Z c forms a ring structure with the silicon atom of a unit and has 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, or C 1 -C 6 Alkyl group, C 1 -C 6 Alkoxy groups, and groups 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 relates to a rubber composition comprising: The present invention also relates to a tire comprising a rubber composition according to the invention, preferentially a tire comprising 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 "between a and b" denotes a range of values ​​greater than "a" and less than "b" (i.e. excluding the limits a and b), whereas any interval of values ​​indicated by the expression "a to b" means a range of values ​​extending from "a" up to "b" (i.e. including the precise limits a and b). The abbreviation "phr" means parts by weight per 100 parts of elastomer (or the sum of the elastomers if several elastomers are present). The compounds referred to herein may be of fossil origin or bio-based. In the latter case, they may be derived partly or entirely from biomass or may be obtained from renewable starting materials derived from biomass. Likewise, the compounds referred to may originate from the recycling of pre-used materials, i.e. they may come partly or entirely from recycling processes or may be obtained from starting materials which themselves come from recycling 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, the tire being reinforced by a carcass reinforcement fixed to the two beads. A non-pneumatic tire usually comprises, for its part, a base, for example designed to be mounted on a rigid rim, a crown reinforcement that ensures the connection with the tread, and a deformable structure, such as spokes, ribs, cells, which is 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 all the embodiments of the invention, the tire according to the invention is preferentially a pneumatic tire. Unless otherwise indicated, the content of units resulting from the insertion of a monomer into a copolymer, such as the copolymers useful in the present invention, is expressed as a molar percentage relative to the total monomer units of the copolymer.

[0007] The elastomers useful for the purposes of the present invention are highly saturated diene elastomers, preferably statistical, containing ethylene units resulting from the polymerization of ethylene. In the known manner, the expression "ethylene unit" refers to the -(CH 2 -CH 2 Highly saturated diene elastomers are rich in ethylene units because they account for more than 50 mol % of the total monomer units of the elastomer.

[0008] Preferably, the highly saturated diene elastomer comprises at least 60 mol% of ethylene units, preferentially at least 65 mol% of ethylene units, and more preferentially at least 70 mol% of ethylene units. In other words, the ethylene units in the highly saturated diene elastomer preferentially account for at least 60 mol% of the total monomer units of the highly saturated diene elastomer, and more preferentially at least 65 mol% of the total monomer units of the highly saturated diene elastomer. Even more preferentially, the ethylene units account for at least 70 mol% of the total monomer units of the highly saturated diene elastomer. Preferably, the ethylene units in the highly saturated diene elastomer account for no more than 90 mol% of the total monomer units of the highly saturated diene elastomer. More preferentially, the ethylene units account for no more than 85 mol% of the total monomer units of the highly saturated diene elastomer. Even more preferentially, the ethylene units account for no more than 80 mol% of the total monomer units of the highly saturated diene elastomer. According to an advantageous embodiment, the highly saturated diene elastomer comprises 60 mol% to 90 mol% of ethylene units, in particular 60 mol% to 85 mol% of ethylene units, said molar percentage being calculated based on the total monomer units of the highly saturated diene elastomer, and more advantageously, the highly saturated diene elastomer comprises 60 mol% to 80 mol% of ethylene units, said molar percentage being calculated based on the total monomer units of the highly saturated diene elastomer.

[0009] According to another advantageous embodiment, the highly saturated diene elastomer comprises 65 mol% to 90 mol% of ethylene units, more particularly 65 mol% to 85 mol% of ethylene units, said molar percentage being calculated based on the total monomer units of the highly saturated diene elastomer, and more advantageously, the highly saturated diene elastomer comprises 65 mol% to 80 mol% of ethylene units, said molar percentage being calculated based on the total monomer units of the highly saturated diene elastomer. According to yet another advantageous embodiment of the present invention, the highly saturated diene elastomer comprises 70 mol% to 90 mol% of ethylene units, in particular 70 mol% to 85 mol% of ethylene units, said molar percentage being calculated based on the total monomer units of the highly saturated diene elastomer, more advantageously, the highly saturated diene elastomer comprises 70 mol% to 80 mol% of ethylene units, said molar percentage being calculated based on the total monomer units of the highly saturated diene elastomer. Highly saturated diene elastomers are copolymers of ethylene and 1,3-dienes and therefore also contain 1,3-diene units resulting from the polymerization of 1,3-dienes. In a known manner, the expression "1,3-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. 1,3-diene units are units of 1,3-dienes containing 4 to 12 carbon atoms, such as, for example, 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, in which case the highly saturated diene elastomer is a copolymer of ethylene and 1,3-butadiene, preferably a statistical copolymer of ethylene and 1,3-butadiene.

[0010] The highly saturated diene elastomer can be obtained according to various synthetic methods known to those skilled in the art, depending in particular on the targeted microstructure of the highly saturated diene elastomer. In general, it can be prepared by copolymerization of at least a 1,3-diene, preferably 1,3-butadiene, with ethylene, and according to known synthetic methods, in particular in the presence of a catalytic system comprising a metallocene complex. Mention may be made of catalytic systems based on metallocene complexes, which are described in the name of the applicant in EP 1 092 731, WO 2004 / 035639, WO 2007 / 054223 and WO 2007 / 054224. The highly saturated diene elastomers can also be prepared through processes using preformed type catalyst systems, including those described in WO 2017 / 093654, WO 2018 / 020122 and WO 2018 / 020123, including when they are statistical. Advantageously, the diene elastomers are statistical and are preferentially prepared through semi-continuous or continuous processes, as described in WO 2017 / 103543, WO 2017 / 13544, WO 2018 / 193193 and WO 2018 / 193194. The highly saturated diene elastomers may carry functional groups containing one or more heteroatoms, such as nitrogen, oxygen, silicon or halogens. Functional groups may be introduced into the highly saturated diene elastomers during or after their synthesis, as described, for example, in WO 2017 / 097831. According to any one embodiment of the invention, the highly saturated diene elastomer is preferentially a hydrocarbon-based polymer, i.e. consisting only of hydrogen and carbon atoms. The highly saturated diene elastomer preferably contains units of formula (I) or units of formula (II).

[0011] [ka] The presence in the copolymer of 1,2-cyclohexanediyl, which is a saturated six-membered ring unit of formula (I), can result from a very specific series of insertions of ethylene and 1,3-butadiene during the growth of the polymer chain. When the highly saturated diene elastomer contains units of formula (I) or units of formula (II), the molar percentages of the units of formula (I) and the units of formula (II) in the highly saturated diene elastomer are o and p, respectively, preferably satisfying the following formula (Formula 1) or formula (Formula 2), and o and p are calculated based on all the monomer units of the highly saturated diene elastomer. 0 < o + p ≤ 30 (Formula 1) 0 < o + p < 25 (Formula 2)

[0012] Preferably, the highly saturated diene elastomer contains units of formula (I) in a molar content greater than 0% and less than 15%, more preferably less than 10 mol%, and the molar percentage is calculated based on all the monomer units of the highly saturated diene elastomer. In addition to the highly saturated diene elastomer, the rubber composition can contain a second diene elastomer. The term "diene elastomer" means an elastomer (i.e., a homopolymer or copolymer) that is at least partially derived from diene monomer units (monomers having two conjugated or non-conjugated carbon-carbon double bonds). Diene monomer units are known as diene units. The second elastomer can be selected from the group of highly unsaturated diene elastomers consisting of polybutadiene, polyisoprene, butadiene copolymers, isoprene copolymers, and mixtures thereof. The highly unsaturated elastomer contains more than 50 mol% of diene units. Preferably, the content of highly saturated diene elastomer in the rubber composition is at least 50 parts by weight per 100 parts of elastomer of the rubber composition (phr). More preferentially, the content of highly saturated diene elastomer in the rubber composition varies in a range ranging from 80 to 100 phr. Even more preferentially, it varies in a range ranging from 90 to 100 phr. Advantageously, it is 100 phr. The highly saturated diene elastomer may be a single highly saturated diene elastomer or a mixture of highly saturated diene elastomers which differ from each other in terms of their microstructure or macrostructure. If the rubber composition contains several highly saturated diene elastomers which differ from each other in terms of their microstructure or macrostructure, the content of highly saturated diene elastomer in the rubber composition refers to a mixture of highly saturated diene elastomers.

[0013] The silica used may be any reinforcing silica known to those skilled in the art, in particular one having a BET specific surface area and a CTAB specific surface area of ​​450 m 2 / g, preferably 30 to 400m 2 / g, especially 60-300m 2 The specific surface area may be any precipitated or fumed silica ranging from 0.01 to 0.05 / g. In the present disclosure, the BET specific surface area is determined by gas adsorption using the Brunauer-Emmett-Teller method described in “The Journal of the American Chemical Society”, (vol. 60, page 309, February 1938), and more specifically according to the method taken from the standard NF ISO 5794-1, Appendix E, June 2010 [multipoint (5-point) volumetric method - gas: nitrogen - degassing under vacuum: 160°C for 1 hour - relative pressure p / po range: 0.05 to 0.17]. The CTAB specific surface area values ​​were determined according to the standard NF ISO 5794-1, Appendix G, June 2010. This process is based on the adsorption of CTAB (N-hexadecyl-N,N,N-trimethylammonium bromide) on the “outer” surface of the reinforcing filler.

[0014] All kinds of precipitated silicas can be used, in particular highly dispersible silicas (HDS). These precipitated silicas can be either highly dispersible or not and are well known to those skilled in the art. Mention can be made, for example, 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® 1115MP, Zeosil® 1165MP, Zeosil® Premium 200MP and Zeosil® HRS 1200MP 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 HDP 320G silicas from PPG.

[0015] The reinforcing fillers may include any kind of "reinforcing" filler other than silica, such as carbon black, known to be capable of reinforcing rubber compositions that can be used in particular in the manufacture of tires. Suitable carbon blacks include all carbon blacks, in particular blacks conventionally used in tires or their treads. Among said carbon blacks, more particularly mention may be made of the reinforcing carbon blacks of the 100, 200 and 300 series, or blacks 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 blacks. These carbon blacks may be used in the isolated form commercially available or in any other form, for example as a support for some of the rubber engineering 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 range from 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 coloring (black pigmentation) and UV stabilizing properties of carbon black are utilized without adversely affecting the typical performance qualities contributed by silica. Silica preferably 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 relative to the total weight of the reinforcing filler. More preferably, silica represents more than 85% by weight of the reinforcing filler.

[0016] The total reinforcing filler content can vary in a wide range, for example from 30 phr to 150 phr. According to a first embodiment, the total reinforcing filler content ranges from 30 phr to 60 phr. According to a second embodiment, the total reinforcing filler content ranges from more than 60 phr to 150 phr. The first embodiment is preferred over the second embodiment due to the use of the rubber composition in the tread having a very low rolling resistance. Any one of these ranges of the total reinforcing filler content can be applied to any of the embodiments of the present invention.

[0017] To couple the silica to the highly saturated diene elastomer, a silane coupling agent (or bonding agent) that is at least difunctional is used to ensure sufficient interlinking of chemical and / or physical properties between the silica and the diene elastomer. The rubber composition according to the present invention comprises as coupling agent an organofunctional silane that contains at least one blocked mercaptosilane unit, at least one mercaptosilane unit, and at least one functional group that is a hydroxyalkoxysilyl group or a cyclic dialkoxysilyl group. The organofunctional silane corresponds to the following formula (1): (A) p (B) q (1) During the ceremony, A is a symbol representing a blocked mercaptosilane unit corresponding to formula (2),

[0018] [ka] - B is a symbol representing a mercaptosilane unit corresponding to formula (3), [ka] In formula (2), R 3 is a hydrogen atom, a linear or branched C 1 -C 18 Alkyl, linear or branched C 2 -C 18 alkenyl. In formulas (2) and (3), each R 4 is a linear or branched C 1 -C 6 each Z is independently selected from saturated hydrocarbon-based divalent groups; b forms a bridge structure between a silicon atom of one unit and a silicon atom of another unit (the units may be the same or different), (-O-) 0.5 and [-O(R 0 CR 0 ) f O-] 0.5are independently selected from the symbol R 0 may be the same or different, and each represents a hydrogen atom or C 1 -C 3 alkyl, f is a number ranging from 2 to 15, and each Z c forms a ring structure with the silicon atom of a unit and has 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, C 1 -C 6 Alkyl group, C 1 -C 6 Alkoxy groups, and groups 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, 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. p is a number in the range of 1 to 20, and q is a number in the range of 1 to 20.

[0019] For purposes of this invention, the term "organofunctional silane" means a silane or mixture of silanes having 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 and a thiol functional group (-SH) linked to a carbon atom. 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 sequence of the blocked mercaptosilane repeating units (A) and the mercaptosilane repeating units (B) is random. In particular, the sequence 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.

[0020] 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. The term "cyclic dialkoxysilyl group" refers to a group in which a silicon atom is linked to two oxygen atoms, each attached to a different carbon atom of the same alkylene group. The term "bridged structure" refers to a chemical structure composed of a covalent bond that allows the connection of two repeating units, which may be identical or different. The group C n -C m The notation refers to the number of carbon atoms that make up the group, which contains n to m carbon atoms, where n and m are integers and m is greater than n. Preferably, R in formula (2) 3 is a hydrogen atom, C 1 -C 10 Alkyl, and C 2 -C 10 In a more preferred manner, R in formula (2) is selected from alkenyl. 3 is a linear C 6 -C 8 In a further preferred manner, the symbol R in formula (2) is 3 is heptyl (C 7 H 15 -).

[0021] Preferably, each R in formulas (2) and (3) 4 are independently linear C 1 -C 4More preferably, each R 4 is propylene. Preferably, 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 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 [-OCH 2 CH(CH 3 )CH 2 O-] 0.5 has. Preferably, each Z in formulas (2) and (3) c is 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 More preferentially, each Z in formula (2) and (3) is independently selected from the group consisting of: c is the formula [-OCH 2 CH(CH 3 )CH 2 O-] 0.5 has.

[0022] Preferably, each X in formulae (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 formulae (2) and (3) is the same and is selected from the group consisting of hydroxyl, methoxy, ethoxy, and 3-hydroxy-2-methylpropoxy. Very advantageously, in formulas (2) and (3), R 3 is heptyl (C 7 H 15 -), and each R 4 is propylene, and each Z b is the formula (-O-) 0.5 or the formula [-OCH 2 CH(CH 3 )CH 2 O-] 0.5 and each Z c is the formula [-OCH 2 CH(CH 3 )CH 2 O-] 0.5 wherein 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. (-O-) 0.5 and [-O(R 0 CR 0 ) f O-] 0.5 The notations (-O-) and (-O-) refer 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. They represent half of the oxygen atoms, i.e., half of the oxygen atoms bonded to the silicon atoms of the repeating units, or half of the dialkoxy groups, i.e., half of the dialkoxy group atoms bonded to the silicon atoms of the repeating units, with the other half of the oxygen atoms or the other half of the dialkoxy groups, respectively, being understood to be linked to another silicon atom of another repeating unit of the oligomer structure, which may be the same or different. Thus, (-O-) 0.5forms a siloxane bond between two silicon atoms in 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 a cyclic structure (the intramolecular structure is represented by Z c ) may form either [-O(R 0 CR 0 ) f O-] 0.5 The two oxygen atoms of are linked to the silicon atom of the unit. One skilled in the art will appreciate that in a compound of formula (1), the bridging structures may be the same or different between the repeating units. For example, the bridging structure may be -Si-O(R 0 CR 0 ) f It may have the O-Si- type or -Si-O(R 0 CR 0 ) f It may also be a mixture of O-Si- and -Si-O-Si- crosslinked structures.

[0023] Preferentially, the organofunctional silane has a molar percentage of blocked mercaptosilane units (A) ranging from 20% to 80% and a molar percentage of mercaptosilane units (B) ranging from 80% to 20%. More preferentially, the organofunctional silane has a molar percentage of blocked mercaptosilane units (A) ranging from 40% to 60% and a molar percentage of mercaptosilane units (B) ranging from 60% to 40%. Even more preferentially, the organofunctional silane has a molar percentage of blocked mercaptosilane units ranging from 50% to 55% and a molar percentage of mercaptosilane units ranging from 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 in any manner known to the person skilled in the art, for example by 1 It can be determined via 1 H NMR analysis.

[0024] The coupling agent organofunctional silane can be obtained via a synthesis process comprising at least one step (a) of a transesterification reaction between a diol compound of formula (4) and at least one blocked mercaptosilane compound of formula (5) and at least one mercaptosilane compound of formula (6): HO(R 0 CR 0 ) f OH (4) (RO) 3 SiR 4 SC(=O)R 3 (5) (RO) 3 SiR 4 SH (6) R 0 and f are as defined above, i.e., R 0 represents a hydrogen atom, methyl, ethyl, or propyl, and f is a number ranging from 2 to 15; R, which may be the same or different, is a linear C 1 -C 6 Represents an alkyl group, R 3 and R 4 is as defined above, i.e., R 4 is a linear or branched saturated divalent C 1 -C 6 R represents a hydrocarbon-based group. 3 is a hydrogen atom, a linear or branched C 1 -C 18 Alkyl, or linear or branched C 2 -C 18 Represents alkenyl.

[0025] The transesterification reaction is a reaction well known to those skilled in the art and can be carried out in the presence of a transesterification catalyst, such as a strong acid. Preferentially, in the above process, the diol compound of formula (4) is HOCH 2 CH 2 CH 2 OH, HOCH 2 CH2 CH 2 CH 2 OH, and HOCH 2 CH(CH 3 )CH 2 More preferentially, in the above process, the diol compound of formula (4) is selected from HOCH 2 CH(CH 3 )CH 2 It is OH. Preferentially, the compounds of formula (5) and (6) used in the above process are those in which the R group is selected from methyl, ethyl, propyl, iso-propyl, n-butyl and iso-butyl. Preferentially, the compound of formula (5) used in the above process is R 3 is a hydrogen atom, a linear or branched C 1 -C 10 Alkyl, or linear or branched C 2 -C 10 More preferentially, the compound of formula (5) used in the above process is R 3 is a linear C 6 -C 8 Even more preferentially, the compound of formula (5) used in the above process is R 3 Heptyl (C 7 H 15 -).

[0026] Preferably, the compounds of formula (5) and (6) used in carrying out the above-mentioned process each R 4 are independent and linear C 1 -C 4 More preferentially, the compounds of formula (5) and (6) used in carrying out the above process are those in which each R 4 is propylene. Preferably, the compounds of formula (5) and (6) used in carrying out the above-mentioned process are 3 is heptyl, and R 4is propylene, R may be the same or different (preferably the same) and is selected from methyl, ethyl, propyl, isopropyl, n-butyl, and iso-butyl, and the compound of formula (4) used in carrying out the above process is HOCH 2 CH(CH 3 )CH 2 It is OH. A mixture of compounds of formula (5) and a mixture of compounds of formula (6) can be used to synthesize an organofunctional silane coupling agent.

[0027] The process of synthesizing the coupling agent may also include: - at least one step (b) of treating the product obtained in step (a) to convert some of the blocked thiol functions, if 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 present in the product obtained in step (a), into blocked thiol functions, and / or - at least one step (d) of partially hydrolyzing the product obtained in step (a), or, if step (b) is carried out in the process, the product obtained in step (b), and, if step (c) is carried out in the process, the product obtained in step (c). 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 the thiol functions of the product obtained in step (a) into carboxylic acids, in particular C 7 H 15 COOH) or acyl chloride (especially C 7 H 15COCl) to esterify them and convert them into blocked thiol functions. A partial hydrolysis step (d) may be optionally performed if excess water is present relative to the products and reagents used in step (a) and if present in steps (b) and (c). The partial hydrolysis step provides Z b is (-O-) 0.5 or OH.

[0028] The skilled person may refer in particular to WO 2007 / 098120, which describes a process 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 process and can be used in the form of this mixture in the rubber composition according to the invention, the mixture containing 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), b v Z a t It differs from equation (2) in that it is replaced by Z a has the same definition as the X group 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), b v Z a t This differs from equation (3) in that it is replaced by Z a has the same definition as the X group 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), - an oligomer consisting of blocked mercaptosilane units of formula (2) - an oligomer consisting of mercaptosilane units of formula (3):

[0029] 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 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 and 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 usually provided in the form of molecular sulfur or in the form of a sulfur donor, preferably in molecular form. Sulfur in molecular form is also referred to by the term "molecular sulfur". The term "sulfur donor" means any compound that releases sulfur atoms that can be inserted into the polysulfide chains formed during vulcanization to crosslink the elastomer chains (which may be combined in the form of polysulfide chains). Various known secondary vulcanization accelerators or vulcanization activators, such as zinc oxide, stearic acid, and guanidine derivatives (especially diphenylguanidine), are added to the vulcanization system and incorporated during the first non-productive and / or productive phase. 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 can be applied to any one of the embodiments of the invention.

[0030] As vulcanization accelerators (primary or secondary), any compound capable of acting as an accelerator for the vulcanization of diene elastomers in the presence of sulfur can be used, in particular thiazole type accelerators and their derivatives, sulfenamide type accelerators for the primary accelerators, or thiuram type, dithiocarbamate type, dithiophosphate type, thiourea type and xanthate type accelerators for the secondary accelerators. Examples of primary accelerators include, in particular, 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-benzothiazylsulfenamide. Examples of secondary accelerators include thiuram disulfides, such as tetraethyl thiuram disulfide, tetrabutyl thiuram disulfide ("TBTD"), tetrabenzyl thiuram disulfide ("TBZTD"), and mixtures of these compounds, among others. The secondary accelerator is preferentially a thiuram disulfide, more preferentially tetrabenzyl thiuram disulfide.

[0031] Vulcanization is generally carried out in known manner at temperatures between 130° C. and 200° C. for a sufficient time which may range, for example, between 5 and 90 minutes, depending in particular on the cure temperature, on the vulcanization system employed, and on the vulcanization kinetics of the composition under consideration. The rubber composition according to the invention may also contain all or part of the usual additives customarily used in elastomeric compositions intended for the manufacture of tires, in particular pigments, protective agents such as antiozonant waxes, chemical antiozonants, antioxidants or plasticizers such as plasticizing oils or resins. The rubber composition before vulcanization can be prepared in a suitable mixer, according to procedures well known to those skilled in the art, using two successive preparation stages: a first stage of thermomechanical working or kneading at high temperatures up to a maximum temperature between 110°C and 190°C, preferably between 130°C and 180°C (sometimes called the "non-productive" stage), followed by a second stage of mechanical working at lower temperatures, typically below 110°C, for example between 40°C and 100°C (sometimes called the "productive" stage), during which the finishing stage sulfur or sulfur donors and vulcanization accelerators are incorporated.

[0032] By way of example, the first (non-productive) stage is carried out in a single thermomechanical step, during which all the necessary components, except the vulcanization system, optional auxiliary processing aids and various other additives, are introduced into a suitable mixer, such as a standard internal mixer. The total mixing time in this non-productive stage is preferably between 1 and 15 minutes. Thus, after cooling the mixture obtained during the first non-productive stage, the vulcanization system is incorporated at low temperature, generally in an external mixer, such as an open mill, and the whole is then mixed for a few minutes, for example between 2 and 15 minutes (productive stage). The rubber composition can be calendered or extruded in the form of sheets or plaques, especially for laboratory characterization, or else in the form of rubber semi-finished products (or profiled elements) that can be used in tires. The composition can be either in the green state (before crosslinking or vulcanization) or in the cured state (after crosslinking or vulcanization). It can consist of all or part of a semi-finished article intended for use in pneumatic or non-pneumatic tires, especially including treads, and in particular in tire treads. In summary, the present invention is advantageously carried out according to any one of the following embodiments 1 to 35:

[0033] Embodiment 1: - highly saturated diene elastomers which are copolymers of ethylene and 1,3-diene, the ethylene units representing more than 50 mol % of the monomer units of the copolymer; - Vulcanization system, - reinforcing fillers containing silica, and an organofunctional silane coupling agent 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, and corresponding to formula (1) (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;

[0034] [ka] During the ceremony, R 3 is a hydrogen atom, a linear 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 b forms a bridge structure between a silicon atom of one unit and a silicon atom of another unit (the units may be the same or different), forming (-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 C 1 -C 3 alkyl, and f is a number ranging from 2 to 15; each Z c forms a ring structure with the silicon atom of a unit and has the formula [-O(R 0 CR 0 ) f O-] 0.5 is a group of R 0and f is as defined above, Each X is a hydrogen atom, a hydroxyl group, or C 1 -C 6 Alkyl group, C 1 -C 6 Alkoxy groups, and groups 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; A rubber composition comprising:

[0035] Embodiment 2: The rubber composition of embodiment 1, wherein the 1,3-diene is 1,3-butadiene or a mixture of 1,3-dienes, one of which is 1,3-butadiene. Embodiment 3: The rubber composition of embodiment 1 or 2, wherein the 1,3-diene is 1,3-butadiene. Embodiment 4: The rubber composition according to any one of embodiments 1 to 3, wherein the ethylene units of the highly saturated diene elastomer account for at least 60 mol % of the total monomer units of the highly saturated diene elastomer.

[0036] Embodiment 5: The rubber composition according to any one of embodiments 1 to 4, wherein the ethylene units of the highly saturated diene elastomer account for at least 65 mol % of the total monomer units of the highly saturated diene elastomer. Embodiment 6: The rubber composition according to any one of embodiments 1 to 5, wherein the ethylene units of the highly saturated diene elastomer account for at least 70 mol % of the total monomer units of the highly saturated diene elastomer. Embodiment 7: The rubber composition according to any one of embodiments 1 to 6, wherein the ethylene units of the highly saturated diene elastomer account for 90 mol % or less of the total monomer units of the highly saturated diene elastomer.

[0037] Embodiment 8: The rubber composition according to any one of embodiments 1 to 7, wherein the ethylene units of the highly saturated diene elastomer account for 85 mol % or less of the total monomer units of the highly saturated diene elastomer. Embodiment 9: The rubber composition according to any one of embodiments 1 to 8, wherein the ethylene units of the highly saturated diene elastomer account for 80 mol % or less of the total monomer units of the highly saturated diene elastomer. Embodiment 10: The rubber composition according to any one of embodiments 1 to 9, wherein the highly saturated diene elastomer contains units of formula (I) or units of formula (II).

[0038] [ka]

[0039] Embodiment 11: A rubber composition according to any one of embodiments 1 to 10, wherein the highly saturated diene elastomer comprises units of formula (I) in a molar content greater than 0% and less than 15%, the molar percentage being calculated based on the total monomer units of the highly saturated diene elastomer. [ka] Embodiment 12: A rubber composition according to any one of embodiments 1 to 11, wherein the highly saturated diene elastomer comprises units of formula (I) in a molar content greater than 0% and less than 10 mol%, the molar percentage being calculated based on the total monomer units of the highly saturated diene elastomer. [ka]

[0040] Embodiment 13: The rubber composition according to any one of embodiments 1 to 12, wherein the highly saturated diene elastomer is a statistical copolymer. Embodiment 14: The rubber composition according to any one of embodiments 1 to 13, wherein the content of the highly saturated diene elastomer is at least 50 parts by weight per 100 parts of elastomer (phr) of the rubber composition. Embodiment 15: The rubber composition according to any one of embodiments 1 to 14, wherein the content of highly saturated diene elastomer varies within the range of 80 to 100 phr. Embodiment 16: The rubber composition according to any one of the embodiments 1 to 15, wherein the total content of reinforcing fillers varies within the range of 30 to 150 phr. Embodiment 17: The rubber composition according to any one of the embodiments 1 to 16, wherein the total reinforcing filler content varies within the range of 30 phr to 60 phr.

[0041] Embodiment 18: The rubber composition of any one of embodiments 1 to 17, wherein silica comprises more than 50% by weight of the reinforcing filler. Embodiment 19: The rubber composition of any one of embodiments 1 to 18, wherein silica comprises more than 85% by weight of the reinforcing filler. Embodiment 20: R in formula (2) 3 is a hydrogen atom, C 1 -C 10 Alkyl, and C 2 -C 10 20. The rubber composition according to any one of embodiments 1 to 19, wherein the aryl group is selected from alkenyl. Embodiment 21: R in formula (2) 3 But linear C 6 -C 8 21. The rubber composition according to any one of the preceding embodiments, wherein the aryl group is alkyl, more preferentially heptyl. Embodiment 22: R in formulas (2) and (3) 4 However, independently, linear C 1 -C 4 The rubber composition according to any one of embodiments 1 to 21, wherein the alkylene is alkylene. Embodiment 23: Each R in formula (2) and (3) 4 23. The rubber composition according to any one of embodiments 1 to 22, wherein is propylene.

[0042] Embodiment 24: Each Z in formula (2) and (3) b But the formula (-O-) 0.5 , [-OCH 2 CH 2 CH2 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 24. The rubber composition of any one of embodiments 1 to 23, wherein the units are independently selected from the group consisting of: Embodiment 25: Each Z in formula (2) and (3) b But the formula (-O-) 0.5 or [-OCH 2 CH(CH 3 )CH 2 O-] 0.5 The rubber composition according to any one of embodiments 1 to 24, wherein Embodiment 26: Each Z in formula (2) and (3) c is expressed 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 26. The rubber composition of any one of embodiments 1 to 25, wherein the units are independently selected from the group consisting of: Embodiment 27: Each Z in formula (2) and (3) c is expressed by the formula [-OCH 2 CH(CH 3 )CH 2 O-] 0.5 The rubber composition according to any one of embodiments 1 to 26, Embodiment 28: The rubber composition according to any one of embodiments 1 to 27, 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.

[0043] Embodiment 29: The rubber composition according to any one of embodiments 1 to 28, 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 30: The rubber composition according to any one of embodiments 1 to 29, wherein 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%. Embodiment 31: The rubber composition according to any one of embodiments 1 to 30, wherein 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%. Embodiment 32: The rubber composition according to any one of embodiments 1 to 31, wherein 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%. Embodiment 33: The rubber composition according to any one of embodiments 1 to 32, wherein the content of the organofunctional silane coupling agent ranges from 1 to 15 phr.

[0044] Embodiment 34: A rubber composition according to any one of the embodiments 1 to 33, wherein the content of organofunctional silane coupling agent ranges from 1.5 to 10 phr, preferentially from 2 to 5 phr. Embodiment 35: Tire comprising a rubber composition according to any one of embodiments 1 to 34, preferentially in its tread. The above-mentioned, as well as other, features of the invention will be more clearly understood on reading the following description of some embodiments of the invention given by way of non-limiting example. EXAMPLES

[0045] Breaking properties: The tensile test is used to determine the breaking properties. Unless otherwise indicated, this test is carried out according to the French standard NF T 46-002 of September 1988, using H2 type specimens, with a pulling speed of 500 mm / min. The tensile strength (in MPa) and the elongation at break (in %) are measured according to the standard NF T 46-002 at 23°C ± 2°C and also at 100°C ± 2°C. Results are expressed relative to the control on a scale of 100. Values ​​greater than the control value, which is arbitrarily set to 100, indicate improved results, i.e., measurements greater than the control value. Elastomer microstructure by Nuclear Magnetic Resonance (NMR) analysis: The microstructure of the elastomer is 1 As determined by H NMR analysis, 1 If the resolution of the H NMR spectrum is not sufficient to assign and quantify all species, 13 Combined with C NMR analysis. 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.

[0046] For insoluble elastomers that can be swollen in the solvent, a 4 mm z-grad HRMAS probe is used to observe protons and carbons in the proton uncoupled mode. Spectra are acquired at spin rates of 4000 Hz to 5000 Hz. For the measurement of soluble elastomers, a liquid NMR probe is used to observe protons and carbons in the proton uncoupled mode. Preparation of insoluble samples involves the combination of the substance to be analyzed with a deuterated solvent that allows for swelling, typically deuterated chloroform (CDCl). 3 ) in a rotor filled with 10 ...

[0047] Soluble samples were prepared in a deuterated solvent (approximately 25 mg of elastomer per ml), typically deuterated chloroform (CDCl3 The solvent or solvent blend used must always be deuterated, the chemistry of which can be adapted by one skilled in the art. In both cases (soluble or swollen samples): A 30° single pulse sequence is used for proton NMR. The spectral window is adjusted to observe all resonance lines belonging to the molecule being analyzed. The number of integrations is adjusted to provide a sufficient signal-to-noise ratio for quantification of each unit. The recycle delay between each pulse is adjusted to obtain a quantitative measurement. For carbon NMR, a single pulse sequence of 30° is used to avoid "nuclear Overhauser" effects (NOE) and maintain quantitation, with only proton decoupling during acquisition. The spectral window is adjusted to observe all resonance lines belonging to the molecule being analyzed. The number of integrations is adjusted to obtain a signal-to-noise ratio sufficient for quantification of each unit. The recycle delay between each pulse is adjusted to obtain a quantitative measurement.

[0048] NMR measurements are carried out at 25°C. Glass Transition Temperature of Polymer: The glass transition temperature (Tg) is measured using a differential scanning calorimeter according to standard ASTM D3418 (1999). Mooney Viscosity: Mooney viscosity is measured using a vibrating table consistometer as described in 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 (molded) 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, after 4 minutes of rotation, the working torque to maintain this movement is measured. Mooney viscosity (ML) is expressed in "Mooney Units" (MU, 1 MU = 0.83 Newton meters). Preparation of rubber composition: Three rubber compositions C1 to C3 are prepared. These compositions are produced in the following manner: The elastomer, then the silica, the silane coupling agent and the various other materials, except for the vulcanization system, are introduced into an internal mixer (final filling level: about 70% by volume) with an initial tank temperature of about 80° C. The thermomechanical work (non-productive phase) is then carried out in one step, lasting approximately 5 to 6 minutes, until a maximum "drop" temperature of 160° C. is reached. The mixture thus obtained is collected and cooled, then the sulfur and sulfenamide type accelerators are incorporated into the mixer (homofinisher) at 23° C. and everything is mixed for an appropriate time, for example between 5 and 12 minutes (productive phase).

[0049] The rubber compositions C1 to C3 all contain the elastomer E1 which is a highly saturated diene elastomer, a vulcanization system, silica, and a silane coupling agent, but differ from each other in the chemical properties of the silane coupling agent. In the rubber composition C1, the silane coupling agent is a polysulfide silane, bis(3-triethoxysilylpropyl)tetrasulfide, abbreviated as TESPT, having the formula [(C 2 H 5 O) 3 Si(CH 2 ) 3 S 2 ] 2 and is sold by Evonik under the name "Si69". In rubber composition C2, the coupling agent is S-(octanoyl)mercaptopropyltriethoxysilane sold under the name "NXT" by Momentive. In the rubber composition C3, the silane coupling agent is "NXT-Z45" sold by Momentive.

[0050] Rubber compositions C1 and C2 are rubber compositions that do not comply with the present invention because the silane coupling agent does not comply with the formula (1) of the organofunctional silane. Rubber composition C3 is a rubber composition according to the present invention because the coupling agent is an organofunctional silane that complies with formula (1). The formulations (unit: phr) of rubber compositions C1 to C3 are shown in Table 1 (Table 1). In the case of rubber composition C1, taking into account that the coupling agent "Si69" releases free sulfur during reaction with the elastomer, which represents a source of sulfur available for vulcanization, i.e. 0.3 phr, the total sulfur content is the same for each rubber composition. The other three rubber compositions C4 to C6 are prepared by the same procedure used for compositions C1 to C3. They all contain the highly saturated diene elastomer (E1), the vulcanization system, silica, and the organofunctional silane coupling agent "NXT-Z45" of formula (1), and therefore are in accordance with the invention. Compositions C4 and C5 differ from composition C3 by their "NXT-Z45" content. Composition C6 differs from composition C3 in terms of the vulcanization system, since the vulcanization accelerator is a thiuram disulfide instead of a sulfenamide. The formulations (in phr) of rubber compositions C4 to C6 are listed in Table 2 (Table 2). The composition thus obtained is then calendered, after vulcanization at 150° C. (cured state), either in the form of slabs (2-3 mm thick) or thin rubber sheets, or in a profiled form which can be used directly, after cutting to the desired dimensions and / or assembling, for example as a semi-finished product for a tire, in order to measure its physical or mechanical properties.

[0051] The elastomer E1 is a highly saturated diene elastomer, a copolymer of ethylene and 1,3-butadiene, prepared according to the following procedure: In a 70 L reactor containing methylcyclohexane (64 L), ethylene (5600 g), and 1,3-butadiene (2948 g), butyloctylmagnesium (BOMAG) dissolved in methylcyclohexane and the catalyst system are added. The Mg / Nd ratio is 6.2. The volume of the catalyst system solution introduced is 840 mL, and the Nd concentration of the catalyst system solution is 0.0065 M. The polymerization reaction starts when the reaction temperature is adjusted to 80 °C. The polymerization reaction is carried out at a constant pressure of 8.3 bar. The reactor is fed with ethylene and 1,3-butadiene in a molar ratio of 73 / 27 during the polymerization. The polymerization reaction is stopped by cooling, degassing the reactor, and adding ethanol. An antioxidant is added to the polymer solution. After steam distillation and drying to constant weight, the copolymer is recovered. The polymerization time is 225 min. From the weighed mass (6.206 kg) it is possible to determine 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 ML value of the copolymer is equal to 62. The catalyst system is a preformed catalyst system. It contains 0.0065 mol / L of the metallocene [Me 2 SiFlu 2 Nd(μ-BH 4 ) 2 Li(THF)], the cocatalyst butyloctylmagnesium (BOMAG) (the BOMAG / Nd molar ratio is equal to 2.2) and the preformed monomer 1,3-butadiene (the 1,3-butadiene / Nd molar ratio is equal to 90) in methylcyclohexane. The medium is heated at 80° C. for 5 hours. It is prepared according to the preparation method according to paragraph II.1 of patent application WO 2017 / 093654.

[0052] The results of the rupture properties of the rubber compositions in the cured state are summarized in Tables 3 and 4. Table 3 shows that rubber composition C3 is the rubber composition with the best breaking properties at both 23° C. and 100° C. Both the breaking elongation and tensile strength of rubber composition C3 are much higher than those of compositions C1 and C2 at both 23° C. and 100° C., respectively. Table 4 shows that improvements in rupture properties are obtained for different contents of silane coupling agent "NXT-Z45" than in composition C3, and also for different vulcanization systems.

[0053] [Table 1] [Table 2] (1) Ethylene-1,3-butadiene copolymer 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, Tg -44°C. (2) Solvay-Rhodia's "Zeosil 1165 MP" in microbead form (3) Evonik's "Si69" triethoxysilylpropyl tetrasulfide (TESPT) liquid silane (4) Silane 3-octanoylthio-1-propyltriethoxysilane ("NXT") - CAS 220727-26-4 - Momentive (5) Silane mercapto-thiocarboxylate oligomer ("NXT-Z45") - CAS 922519-17-3 - Momentive (6) Diphenylguanidine, "Perkacit DPG" from Flexsys (7) Sasol Wax's "Varazon 4959" ozone depletion prevention wax (8) N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, "Santoflex 6-PPD" from Flexsys (9) Uniqema's "Pristerene 4931" stearic acid (10) Zinc Oxide, Industrial Grade, Umicore (11) N-Cyclohexyl-2-benzothiazole sulfenamide, "Santocure CBS" from Flexsys (12) Tetrabenzyl thiuram disulfide (Perkacit TBZTD from Flexsys) - CAS 10591-85-2

[0054] [Table 3] [Table 4]

Claims

1. - highly saturated diene elastomers which are copolymers of ethylene and 1,3-diene, the ethylene units representing more than 50 mol % of the monomer units of said copolymer; - vulcanization system, - reinforcing fillers containing silica, and 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, and corresponding to formula (1): (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】 During the ceremony, R 3 represents a hydrogen atom, a linear 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 b forms a bridge structure between a silicon atom of one unit and a silicon atom of another unit (the units may be the same or different), and (—O—) 0.5 and [-O(R 0 CR 0 ) f O-] 0.5 independently selected from 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 c forms a ring structure with the silicon atom of a certain unit and has 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 in the range of 1 to 20; q is a number in the range of 1 to 20; A rubber composition comprising:

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

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

4. The rubber composition of claim 1 , wherein silica comprises more than 50% by weight of the reinforcing filler.

5. 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.

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

7. 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:

8. 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:

9. 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.

10. 2. The rubber composition of claim 1, wherein the organofunctional silane has a mole percentage of blocked mercaptosilane units (A) ranging from 20% to 80% and a mole percentage of mercaptosilane units (B) ranging from 80% to 20%.

11. A tire comprising the rubber composition according to any one of claims 1 to 10.

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