Rubber composition comprising a highly saturated dienic elastomer

Description

1 / 22 “RUBBER COMPOSITION COMPRISING A HIGHLY SATURATED DIENE ELASTOMER”

[0001] The present invention relates to rubber compositions including a highly saturated diene elastomer, the rubber compositions being particularly intended for use in a tread for a heavy-duty tire.

[0002] Tires designed for vehicles carrying heavy loads include specific characteristics of dimensions, robustness, and architecture that distinguish them from other tires, notably tires for equipping passenger vehicles. Their treads must meet a large number of technical requirements, often conflicting, such as low rolling resistance, high wear resistance, as well as good resistance to damage from foreign bodies present on the surface on which the tire rolls.

[0003] In fact, the use of these tires on terrains with numerous pebbles and other objects or holes causes wear on the tread. For equipment carrying heavy loads, particularly heavy vehicles, it is known that the treads of the tires fitted to these vehicles are subjected to repetitive impacts that can cause material to detach from the tread. It is therefore necessary that the tire treads of these vehicles exhibit good resistance to wear as well as better stretch-to-tear strength in order to limit the appearance of cracks in the rubber compounds that make up these treads. Stretch-to-tear strength corresponds to the ability of these compounds to deform without breaking.It is also important to consider tear resistance (the ability of the compounds to resist the propagation of cracks) and fatigue resistance (the ability of the compounds to withstand the numerous mechanical demands that are repeatedly applied cyclically during tire wear). Improvements in stretch-to-tear strength should preferably occur without significantly impacting tear resistance and fatigue resistance, while simultaneously improving them. Petition 870260074934, dated 07 / 28 / 2026, page 13 / 37 2 / 22

[0004] Thus, manufacturers are always looking for solutions to further improve tensile strength properties while keeping tear resistance properties within acceptable limits.

[0005] Following these searches, the Applicant unexpectedly found that adding a specific amount of polyisoprene to a rubber compound that comprises mostly a highly saturated diene elastomer allows for further improvement in the aforementioned performance impairment.

[0006] Thus, a first object of the invention is a rubber composition based on at least one elastomeric matrix comprising 85 to 98 phr of at least one copolymer containing ethylene units and 1,3-diene units, the molar fraction of the ethylene units in the copolymer being in the range of more than 50% to 95%, and 2 to 15 phr of a polyisoprene including a mass ratio of 1,4-cis linkages of at least 90% of the mass of the polyisoprene, wherein a reinforcing filler comprises carbon black having a specific BET surface area in the range of 50 to 160 m2 / g and a crosslinking system.

[0007] A second object of the invention is a heavy-duty pneumatic tire comprising a rubber composition as per the invention. I - DEFINITIONS

[0008] The expression “composition based on” should be understood as a composition that includes the mixture and / or the product of in situ reaction of different constituents used, some of these constituents being able to react and / or being intended to react with each other, at least partially, at different stages of the composition's manufacture; the composition may thus be in the fully or partially crosslinked state or in the non-crosslinked state.

[0009] By elastomeric matrix, the set of elastomers in the composition is meant the set of elastomers in the composition, including the copolymer defined below.

[0010] Unless otherwise indicated, the unit rates resulting from the insertion of a monomer into a copolymer are expressed as a molar percent. Petition 870260074934, dated 07 / 28 / 2026, page 14 / 37 3 / 22 in relation to the total number of monomer units in the copolymer.

[0011] The expression "part by weight to one hundred parts by weight of elastomer (or phr)" should be understood, in the sense of the present invention, as the part by mass to one hundred parts of elastomer present in the rubber composition considered.

[0012] In this document, unless expressly stated otherwise, all percentages (%) indicated are percentages (%) by mass.

[0013] On the other hand, any range of values ​​designated by the expression “between a and b” represents the domain of values ​​in the range from more than a to less than b (that is, limits a and b excluded) while any range of values ​​designated by the expression “from a to b” means the domain of values ​​in the range from a to b (that is, including the strict limits a and b). In this document, when a range of values ​​is designated by the expression “from a to b”, it is equally and preferably designated by the range represented by the expression “between a and b”.

[0014] When reference is made to a “major compound,” it is understood within the present invention that this compound is the major compound among compounds of the same type in the composition, that is, it is the one that represents the largest quantity by mass among compounds of the same type. Thus, for example, a major elastomer is the elastomer representing the largest mass relative to the total mass of elastomers in the composition. Similarly, a so-called major filler is the one representing the largest mass among the fillers in the composition. By way of example, in a system comprising a single elastomer, it is the major elastomer within the present invention; and in a system comprising two elastomers, the major elastomer represents more than half of the mass of elastomers. Conversely, a “minor” compound is a compound that does not represent the largest mass fraction among compounds of the same type.Preferably, by "majority" it is understood to mean present in more than 50%, preferably more than 60%, 70%, 80%, 90%, and most preferably the majority compound represents 100%.

[0015] The compounds mentioned in the description may be of fossil or biogenic origin. In the latter case, they may be partially or totally derived from biomass or obtained from renewable raw materials. Petition 870260074934, dated 07 / 28 / 2026, page 15 / 37 4 / 22 derived from biomass. Similarly, the compounds mentioned may also originate from the recycling of already used materials, that is, they may be partially or totally derived from a recycling method, or even obtained from raw materials that are themselves derived from a recycling method. Polymers, plasticizers, fillers, etc. are notably included.

[0016] Unless otherwise indicated, all glass transition temperature values ​​“Tg” described herein are measured in a manner known to be DSC (Differential Scanning Calorimetry) in accordance with ASTM D3418 (1999). II - DESCRIPTION OF THE INVENTION II-1 ELASTOMERIC MATRIX

[0017] According to the invention, the elastomeric matrix comprises 85 to 98 phr of at least one copolymer containing ethylene units and 1,3-diene units, the ethylene units in the copolymer representing between 50% and 95% by mole of the monomer units of the copolymer (hereinafter referred to as the copolymer) and 2 to 15 phr of a polyisoprene including a mass ratio of 1,4-cis linkages of at least 90% by mass of the polyisoprene.

[0018] A copolymer containing ethylene units and 1,3-diene units means any copolymer comprising, within its structure, at least ethylene units and 1,3-diene units. The copolymer may thus comprise monomer units other than ethylene units and 1,3-diene units. For example, the copolymer may also comprise alpha-olefin units, notably alpha-olefin units having from 3 to 18 carbon atoms, advantageously having from 3 to 6 carbon atoms. For example, the alpha-olefin units may be chosen from the group consisting of propylene, butene, pentene, hexene or mixtures thereof. However, the copolymer does not comprise a 1,3-diene unit of the formula CH2=CR-CH=CH2, the symbol R representing a hydrocarbon chain with 3 to 20 carbon atoms.

[0019] As is well known, the expression ethylene unit refers to the -(CH2-CH2)- motif resulting from the insertion of ethylene into the elastomer chain.

[0020] As is well known, the expression 1,3-diene unit refers to Petition 870260074934, dated 07 / 28 / 2026, page 16 / 37 5 / 22 units result from the insertion of 1,3-diene by a 1,4 addition, a 1,2 addition, or a 3,4 addition in the case of a substituted diene such as isoprene, for example.

[0021] Preferably, the 1,3-diene units are selected from the group consisting of butadiene units, isoprene units, and mixtures of these 1,3-diene units. In particular, the 1,3-diene units of the copolymer may be 1,3-diene units with 4 to 12 carbon atoms, for example 1,3-butadiene, 2-methyl-1,3-butadiene (or isoprene) units. More preferably, the 1,3-diene units are mostly, in moles, or preferably exclusively, 1,3-butadiene units.

[0022] In the copolymer, the ethylene units represent between 50% and 95% by mole of the copolymer monomer units. Advantageously, the ethylene units in the copolymer represent between 55% and 90%, preferably 60% to 90%, preferably 60% to 80%, by mole of the copolymer monomer units.

[0023] Advantageously, the copolymer is a copolymer of ethylene and a 1,3-diene (preferably 1,3-butadiene), that is, according to the invention, a copolymer consisting exclusively of ethylene units and a 1,3-diene unit (preferably 1,3-butadiene).

[0024] Preferably, the copolymer does not contain a 1,3-diene unit of the formula CH2=CR-CH=CH2, where R represents a hydrocarbon chain with 3 to 20 carbon atoms.

[0025] When the copolymer is a copolymer of ethylene and a 1,3-diene, it advantageously contains units of formula (I) below and / or (II) below. The presence of a 6-membered saturated cyclic motif, 1,2-cyclohexanedi-yl, of formula (I) as a monomer unit in the copolymer may result from a series of very particular insertions of ethylene and 1,3-butadiene into the polymer chain along its growth. Petition 870260074934, dated 07 / 28 / 2026, page 17 / 37 6 / 22 -CH2-CH(CH=CH2)- (IT)

[0026] For example, the copolymer of ethylene and a 1,3-diene may be devoid of units of formula (I). In that case, it preferably contains units of formula (II).

[0027] When the ethylene-1,3-diene copolymer comprises units of formula (I) or units of formula (II) or even units of formula (I) and units of formula (II), the molar percentages of the units of formula (I) and the units of formula (II) in the copolymer, respectively oep, preferably satisfy the following equation (eq. 1), more preferably equation (eq. 2), oep being calculated on the basis of the set of monomer units of the copolymer. < o+p < 25 (eq. 1) < o+p < 20 (eq. 2)

[0028] According to the invention, the copolymer, preferably the copolymer of ethylene and a 1,3-diene (preferably 1,3-butadiene), is a statistical copolymer.

[0029] Advantageously, the number-average mass (Mn) of the copolymer, preferably of the ethylene-1,3-diene copolymer (preferably 1,3-butadiene), is comprised in a range of 100,000 to 300,000 g / mol, preferably 150,000 to 250,000 g / mol.

[0030] The Mn of the copolymer is determined in a known manner by steric exclusion chromatography (SEC) as described in section 111-1 below.

[0031] The copolymer can be obtained according to different synthesis methods known to those skilled in the art, notably depending on the desired microstructure of the copolymer. Generally, it can be prepared by Petition 870260074934, dated 07 / 28 / 2026, page 18 / 37 7 / 22 copolymerization of at least one diene, preferably a 1,3-diene, more preferably 1,3-butadiene, and ethylene, and according to known synthesis methods, in particular in the presence of a catalytic system comprising a metallocene complex. Catalytic systems based on metallocene complexes, described in documents EP 1 092 731, WO 2004035639, WO 2007054223 and WO 2007054224 on behalf of the Applicant, may be cited in this regard. The copolymer, understood here as statistical, may also be prepared by a method using a preformed type catalytic system such as those described in documents WO 2017093654 A1, WO 2018020122 A1 and WO 2018020123 A1.

[0032] The copolymer may consist of a mixture of copolymers containing ethylene units and 1,3-diene units that differ from each other by their microstructures and / or by their macrostructures.

[0033] Advantageously, the rate of at least one copolymer containing ethylene units and 1,3-diene units may be comprised in a range of 88 to 97 phr, preferably more than 90 to 96 phr.

[0034] Advantageously, the polyisoprene having a 1,4-cis linkage mass ratio of at least 90% by mass is a natural rubber, a synthetic polyisoprene or a mixture thereof. More preferably, the polyisoprene having a 1,4-cis linkage mass ratio of at least 90% by mass is a natural rubber.

[0035] Advantageously, the polyisoprene content in the composition according to the invention is preferably comprised in a range of 3 to 12 phr, preferably from 4 to less than 10 phr. II-2 REINFORCEMENT LOAD

[0036] The composition according to the invention comprises a reinforcing filler, known for its capabilities of reinforcing a rubber composition usable for the manufacture of tires. Such a reinforcing filler typically consists of particles whose average size (by mass) is less than one micrometer, generally less than 500 nm, most frequently between 20 and 200 nm. Petition 870260074934, dated 07 / 28 / 2026, page 19 / 37 8 / 22 nm, in particular and more preferably between 20 and 150 nm.

[0037] According to the invention, the reinforcing filler comprising carbon black has a specific surface area BET comprised in a range of 50 to 160 m2 / g.

[0038] The reinforcing filler may also comprise a reinforcing filler in addition to carbon black, in particular silica, but this is not mandatory.

[0039] For example, the reinforcing filler may comprise more than 50% by weight, preferably more than 90% by weight, preferably 100% by weight, of carbon black. In this case, the reinforcing filler preferably comprises more than 50% by weight, preferably more than 90% by weight, preferably 100% by weight of carbon black having a specific surface area BET comprised in a range of 50 to 160 m2 / g. When the reinforcing filler comprises a mixture of carbon black and silica, the reinforcing filler advantageously comprises 50% to 95% by weight, preferably 60% to 95% by weight of silica and 5% to 50% by weight, preferably 5% to 40% by weight, of carbon black.

[0040] The carbon blacks usable within the scope of the present invention may be any carbon black conventionally used in tires or their treads (so-called tire-grade carbon blacks). Among the latter, the reinforcing carbon blacks of the 100, 200, 300 series (ASTM grades) will be mentioned more particularly, such as N115, N134, N234, N326, N330, N339, N347, N375). These carbon blacks may be used in the isolated state, as commercially available, or in any other form, for example as a carrier for certain tire additives used. The carbon blacks could, for example, already be incorporated into the diene elastomer, notably isoprene in the form of a masterbatch (see, for example, applications WO 97 / 36724 or WO 99 / 16600).

[0041] Among precipitated carbon blacks, those exhibiting a specific surface area BET comprised in a range of 90 to 160 m2 / g, and preferably 100 to 150 m2 / g, are particularly preferred.

[0042] The BET specific surface area of ​​carbon blacks is measured from Petition 870260074934, dated 07 / 28 / 2026, page 20 / 37 9 / 22 in accordance with standard D6556-10 [multiple-point method (minimum 5 points) gas: nitrogen - relative pressure range P / P0: 0.1 to 0.3],

[0043] As silicas may be any type of precipitated silica, notably highly dispersible precipitated silicas (so-called HDS for highly dispersible or highly dispersible silica). These precipitated silicas, whether highly dispersible or not, are well known to those skilled in the art. Examples include the silicas described in applications W003 / 016215-A1 and W003 / 016387-A1. Among commercial HDS silicas, the following can notably be used: Ultrasil® 5000GR, Ultrasil® 7000GR from Evonik, Zeosil® 1085GR, Zeosil® 1115 MP, Zeosil® 1165MP, Zeosil® Premium 200MP, and Zeosil® HRS 1200 MP from Solvay. As for non-HDS silicas, the following commercial silicas can be used: Ultrasil® VN2GR, Ultrasil® VN3GR from Evonik, Zeosil® 175GR from Solvay, and Hi-Sil EZ120G(-D), Hi-Sil EZ160G(-D), and Hi-Sil EZ200G(-D). Hi-Sil 243LD, Hi-Sil 210, Hi-Sil HDP 320G from PPG.

[0044] In the present exposition, the specific surface area BET 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 precisely according to a method adapted from the NF ISO 5794-1 standard, Annex E of June 2010 [volumetric multipoint method (5 points) - gas: nitrogen - vacuum degassing: one hour at 160°C - relative pressure range p / po: 0.05 to 0.17].

[0045] To couple silica to the diene elastomer, a well-known coupling agent (or bonding agent) that is at least bifunctional can be used to ensure a sufficient chemical and / or physical connection between the inorganic filler (the surface of its particles) and the diene elastomer. In particular, at least bifunctional organosilanes or polyorganosiloxanes are used. By bifunctional, it is understood a compound that has a first functional group capable of interacting with the inorganic filler and a second functional group capable of interacting with the diene elastomer. For example, such Petition 870260074934, dated 07 / 28 / 2026, page 21 / 37 10 / 22 bifunctional compound may comprise a first functional group comprising a silicon atom, said first functional group being able to interact with the hydroxyl groups of an inorganic filler and a second functional group comprising a sulfur atom, said second functional group being able to interact with the diene elastomer.

[0046] Preferably, when used, organosilanes are chosen from the group consisting of polysulfated organosilanes (symmetric or asymmetric) such as bis(3-triethoxysilylpropyl) tetrasulfide, abbreviated TESPT, marketed under the name Si69 by Evonik, or bis-(triethoxysilylpropyl) disulfide, abbreviated TESPD, marketed under the name Si75 by Evonik, polyorganosiloxanes, mercaptosilanes, blocked mercaptosilanes, such as S(3-(triethoxysilyl)propyl) octanethioate, marketed by Momentive under the name NXT Silane. More preferably, the organosilane is a polysulfated organosilane.

[0047] When the reinforcing filler comprises silica, the coupling agent content can be easily adjusted by those skilled in the art. Typically, the coupling agent ratio represents 0.5% to 15% by weight relative to the amount of silica.

[0048] The reinforcing load rate can be easily adjusted by those skilled in the art depending on the use of the rubber composition. Advantageously, the reinforcing load rate in the composition according to the invention is comprised in a range of 20 to 70 phr, preferably 30 to 60 phr. II-3 NETTING SYSTEM

[0049] The crosslinking system may be any type of system known to those skilled in the art in the field of rubber compounds for tires. It may notably be sulfur-based and / or peroxide-based and / or bismaleimide-based.

[0050] Preferably, the crosslinking system is sulfur-based, then it is called a vulcanization system. Advantageously, the vulcanization system Petition 870260074934, dated 07 / 28 / 2026, page 22 / 37 11 / 22 comprises molecular sulfur and / or at least one sulfur donor agent. At least one vulcanization accelerator is equally and preferably present, and, optionally, preferably and equally, various known vulcanization activators may be used, such as zinc oxide, stearic acid or equivalent compounds such as stearic acid salts and transition metal salts, guanidine derivatives (in particular difernylguanidine), or known vulcanization retardants.

[0051] Sulfur is used at a preferred rate between 0.5 and 2 phr, in particular between 0.6 and 1.5 phr. The vulcanization accelerator is used at a preferred rate between 0.5 and 2 phr, more preferably between 0.6 and 1.5 phr.

[0052] Any compound capable of acting as an accelerator for the vulcanization of diene elastomers in the presence of sulfur can be used as an accelerator, notably thiazole-type accelerators, as well as their derivatives, sulfenamide-type accelerators, thiurams, dithiocarbamates, dithiophosphates, thioureas, and xanthan gums. Examples of such accelerators include the following compounds: 2-mercaptobenzothializate disulfide (MBTS), N-cyclohexyl-2-benzothiazyl sulfenamide (CBS), and N,N-dicyclohexyl-2-benzothiazyl sulfenamide.

[0053] (DCBS), N-tert-butyl-2-benzothiazyl sulfenamide (TBBS), N-tert-butyl-2-benzothiazyl sulfenimide (TBSI), tetrabenzylthiuram disulfide (TBZTD), zinc dibenzylthiocarbamate (ZBEC) and mixtures of these compounds. II-4 POSSIBLE ADDITIVES

[0054] The rubber compositions according to the invention may optionally include in the same way all or part of the common additives usually used in elastomer compositions for tires, such as plasticizers (such as plasticizing oils and / or plasticizing resins), pigments, protective agents such as anti-ozone waxes, chemical antiozonants, antioxidants, anti-fatigue agents, reinforcing resins (such as described, for example, in application WO 02 / 10269).

[0055] The rubber composition preferably does not comprise granules of Petition 870260074934, dated 07 / 28 / 2026, page 23 / 37 12 / 22 rubber. Rubber granules are understood to be a cross-linked composition based on at least one elastomer and a filler in the form of particles having a size, namely, their diameter in the case of spherical particles or their largest dimension in the case of anisometric particles, of a few tens or hundreds of microns.

[0056] The composition according to the invention does not require the use of reinforcing resins (or solidifying resins) known to those skilled in the art to harden rubber compositions, notably by increasing their Young's modulus or the dynamic shear complex G*. Advantageously, the rubber composition does not comprise formaldehyde resin, preferably not the reinforcing resin. Examples of such reinforcing resins can be found in Chapter II.3 of patent WO20198679A1.

[0057] Advantageously, the composition according to the invention does not comprise liquid plasticizer at 23°C or comprises less than 10 phr, preferably less than 5 phr. Preferably, the composition according to the invention does not comprise liquid plasticizer at 23°C. II-5 Preparation of the compositions

[0058] Rubber compositions conforming to the invention can be manufactured in suitable mixers, using two successive preparation phases well known to those skilled in the art: - a first phase of thermomechanical work or mixing (a so-called non-productive phase), which can be carried out in a single thermomechanical step during which all the necessary constituents are introduced into a suitable mixer, such as a conventional internal mixer (e.g., of the 'Banbury' type), notably the elastomeric matrix, the reinforcing filler, and any other miscellaneous additives, with the exception of the crosslinking system. The incorporation of the filler into the elastomer can be carried out in one or more stages during thermomechanical mixing. In the case where the filler is already incorporated wholly or partially into the elastomer in the form of a masterbatch, as described, for example, in applications WO 97 / 36724 or WO 99 / 16600, it is the masterbatch that is directly mixed and, Petition 870260074934, dated 07 / 28 / 2026, page 24 / 37 13 / 22 If applicable, other elastomers or fillers present in the composition that are not in the form of a master mix are incorporated, as well as any other miscellaneous additives besides the crosslinking system. The non-productive phase can be carried out at high temperature, up to a maximum temperature between 110 °C and 200 °C, preferably between 130 °C and 185 °C, for a duration generally between 2 and 10 minutes. - a second mechanical processing phase (the so-called productive phase), which can be carried out in an external mixer, such as a ball mixer, after cooling the mixture obtained during the first non-productive phase to a lower temperature, typically below 120 °C, for example between 40 °C and 100 °C. The crosslinking system is then incorporated, and the total is then mixed for a few minutes, for example between 5 and 15 minutes.

[0059] These phases were described, for example, in applications EP-A-0501227, EP-A0735088, EP-A-0810258, WO00 / 05300 or WO00 / 05301.

[0060] The final composition thus obtained is then calendered, for example, into a sheet or plate, notably for laboratory characterization, or extruded (or co-extruded with another rubber composition) into a semi-finished (or profile) rubber product usable, for example, as a tire tread. These products can then be used for the manufacture of tires, according to techniques known to those skilled in the art.

[0061] The composition may be in the raw state (before crosslinking or vulcanization), or in the cooked state (after crosslinking or vulcanization), it may be a semi-finished product that can be used in a tire.

[0062] The crosslinking of the composition can be carried out in a manner known to those skilled in the art, for example, at a temperature between 130°C and 200°C, under pressure. II-6 RUBBER ARTICLE

[0063] The present invention also relates to a rubber article comprising at least one composition according to the invention. The article Petition 870260074934, dated 07 / 28 / 2026, p. 25 / 37 14 / 22 of rubber can be selected from the group consisting of tires, conveyor belts, conveyor belts, and anti-vibration articles. Preferably, the rubber article is selected from the group consisting of tires and conveyor belts. Preferably still, the rubber article is a tire.

[0064] In the present invention, a pneumatic (in English, tyre) means a pneumatic or non-pneumatic tire. A pneumatic tire typically includes two protrusions intended to contact a rim, a spike composed of at least one spike frame and a tread, two sidewalls, the tire being reinforced by a carcass frame anchored to the two protrusions. A non-pneumatic tire, for its part, typically includes a base, designed for example for mounting on a rigid rim, a spike frame that ensures the connection with a tread, and a deformable structure, such as spokes, ribs or alveoli, this structure being disposed between the base and the spike. Such non-pneumatic tires do not necessarily comprise a sidewall. Non-pneumatic tires are described for example in documents WO 03 / 018332 and FR2898077.According to any of the embodiments of the invention, the pneumatic component according to the invention is preferably a pneumatic bandage.

[0065] The tire according to the invention can be used to equip any type of vehicle, in particular motor vehicles, without particular limitation. However, considering the performance compromise of the composition according to the invention, it is particularly well suited to heavy-duty tires, in particular to their tread. Thus, the invention also has as its object a heavy-duty tire comprising a composition according to the invention. Preferably, the composition according to the invention is present in the tread of the heavy-duty tire. The composition according to the invention may constitute part or all of the tire tread.

[0066] A heavy-duty tire is understood to be a tire, Petition 870260074934, dated 07 / 28 / 2026, p. 26 / 37 15 / 22 notably with radial carcass frame, for vehicles with a gross vehicle weight rating (GVWR) of more than 3.5 tons. These vehicles are fitted with wheels whose rims have a nominal diameter greater than or equal to 19.5 inches. Thus, preferably, the diameter of the heavy-duty tire according to the invention is comprised in a range of 19.5 to 25 inches. III - EXAMPLES III-1 MEASUREMENTS AND TESTS USED FATIGUE TEST

[0067] Fatigue resistance, expressed in cycle number or relative unit (ur), is measured in a known manner in 12 test tubes subjected to repeated low-frequency tensile stresses up to a stretch of 75%, at 23°C, using a Monsanto apparatus (type MFTR) until the test tube breaks, in accordance with ASTM D4482-85 and ISO 6943 standards.

[0068] The result is expressed on a basis of 100 relative to a control composition. A value higher than that of the control, arbitrarily set at 100, indicates an improved result, i.e., better fatigue resistance of the rubber samples and therefore better durability. Mechanical properties after cooking: Tensile test

[0069] The stretch-to-break (STB%) and shrink-to-break (STB) tests are based on the NF ISO 37 standard of December 2005 in an H2 type dumbbell cylinder and are measured at a tensile speed of 500 mm / min at a temperature of 60°C. The stretch-to-break is expressed as % stretch. The shrink-to-break is expressed in MPa. These values ​​are expressed on a base of 100 relative to a control composition. A value greater than 100 indicates an improvement in the mechanical properties of the composition considered compared to the control composition.

[0070] All these tensile measurements are carried out under normal hygrometric conditions (50+5% relative humidity), in accordance with the French standard NF T 40101 (December 1979). Petition 870260074934, dated 07 / 28 / 2026, p. 27 / 37 16 / 22 TEAR

[0071] Tear indices are measured at 100°C. Notably, the force required to achieve rupture (FRD, in MPa (in N / mm2)) is determined, and the strain at rupture (DRD, in %) is measured in a 10 x 85 x 2.5 mm specimen notched in the center of its length by 3 notches to a depth of 3 mm to cause the specimen to rupture. Thus, the energy to cause rupture (rupture energy) of the specimen can be determined, which is the product of FRD and DRD.

[0072] Rupture energy results are expressed on a base of 100 relative to a control composition. A result greater than 100 indicates an improvement in tear resistance. DETERMINATION OF THE MICROSTRUCTURE OF ELASTOMERS BY NUCLEAR MAGNETIC RESONANCE (NMR):

[0073] Ethylene and 1,3-butadiene copolymers are characterized by ¹H,13C NMR spectrometry. NMR spectra are recorded on a Brüker Avance III 500 MHz spectrometer equipped with a 5 mm BBIz-grad broadband cryo-probe. The quantitative ¹H NMR experiment uses a single 30° pulse sequence and a 5-second repetition time between each acquisition. 64 to 256 accumulations are performed. The quantitative ¹3C NMR experiment uses a single 30° pulse sequence with proton decoupling and a 10-second repetition time between each acquisition. 1024 to 10240 accumulations are performed. Two-dimensional experiments are used to determine the structure of the polymers. The determination of the microstructure of copolymers is defined in the literature, according to the article by Llauro et al., Macromolecules 2001, 34, 6304-6311.

[0074] NMR measurements are performed at 25°C. The copolymers are in solution in a deuterated solvent (approximately 25 mg of elastomer in 1 mL), generally deuterated chloroform (CDC13). DETERMINATION OF POLYMER MACROSTRUCTURE BY STERIC EXCLUSION CHROMATOGRAPHY (SE):

[0075] Size exclusion chromatography (SEC) allows fractionation Petition 870260074934, dated 07 / 28 / 2026, page 28 / 37 17 / 22 of the polymer chains in a solvent according to their hydrodynamic volume. Like all chromatographic systems, the technique is based on the elution of a solute (the polymer) through a column containing a stationary phase. The system is composed, in this order: of a solvent reservoir, a pumping system, an injector, a set of columns, and detectors. The measurement chain is equipped with a Waters Alliance e2695 module and a Waters fRI410 refractometer.

[0076] The mobile phase is eluted at a flow rate of 1 mL / min. The polymer is solubilized in THF in the presence of 1 wt% diisopropylamine and 1 wt% triethylamine at a concentration of 1 g / L. A volume of 100 μL is injected through a set of 3 AGILENT (MIXED B LS) steric exclusion chromatography columns. The columns are thermostated in an oven at 35°C. The stationary phase of the columns is based on a polystyrene divinylbenzene gel with controlled porosity. The polymer chains are separated according to the hydrodynamic volume they occupy when solubilized in the solvent. The more significant the volume they occupy, the less accessible the column pores are and the shorter their elution time. Detection is ensured by a refractometer (RI) thermostated at 35°C. Each elution volume is associated with a mass via Moore calibration (passing a certified standard: standard polystyrenes from Polymer Standard Service (Mainz)).The WATERS: EMPOWER software is used for data acquisition and analysis. It is then possible to determine the median molar masses in number (Mn), the median molar masses in mass (Mw), as well as the polydispersity (Ip = Mw / Mn). Mooney ml 1+4

[0077] For polymers and rubber compounds, Mooney viscosities mL(1+4) at 100°C are measured using an oscillating consistometer according to ASTM D-1646 (1999). The Mooney plasticity measurement is performed according to the following principle: the composition in the raw state (i.e., before baking) is molded in a cylindrical container heated to 100°C. After one minute of preheating, the rotor rotates within the test tube at 2 revolutions / minute and the useful torque for Petition 870260074934, dated 07 / 28 / 2026, page 29 / 37 18 / 22 monitoring this movement after 4 minutes of rotation is measured. The Mooney plasticity mL(1+4) is expressed in Mooney units (MU, with 1 MU = 0.83 Nm). III-2 Synthesis of the El copolymer:

[0078] In the synthesis of ethylene and 1,3-butadiene copolymers, all reagents are commercially obtained except for the metallocenes. The butyloctylmagnesium BOMAG (20% in the heptate, C = 0.88 mol.L⁻¹) is sourced from Chemtura and stored in a Schlenk tube under an inert atmosphere. The ethylene, of N35 quality, is sourced from Air Liquide and is used without prior purification.

[0079] The ethylene-1,3-butadiene copolymer: elastomer El (according to the invention) is synthesized according to the operational mode described below.

[0080] The polymerization of ethylene (grade N35, from Air Liquide, used without prior purification) and 1,3-butadiene is carried out according to a continuous method in solution in methylcyclohexane at 80°C under 11.5 bar in the presence of a catalytic system (94 pmoles of Nd per 100 g of monomers), the mass concentration of monomer feed in the reactor being 6%, the mass ratio of 1,3-butadiene / ethylene being 0.53, and the molar ratio of active Mg / Nd being 3.7. At the desired conversion (73%, 120 minutes) to achieve a Mn of approximately 139 Kg / mol, the polymerization is stopped at the line outlet with the help of an antioxidant solution in methylcyclohexane (0.6 phr of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine and 0.7 phr of 2,2'-methylene-bis(4-methyl-6-tert-butylphenol, phr: part by weight per hundred parts of elastomer).The copolymer is recovered by a steam-driven method called stripping, well known to those skilled in the art, and then dried in a screw conveyor machine fitted with a single screw.

[0081] The catalytic system is a pre-formed catalytic system. It is prepared in methylcyclohexane from a metallocene, [Me2Si(Flu)2Nd(p-BH4)2Li(THF)] at 0.0065 mol / L, a co-catalyst, butyloctylmane (BOMAG) with a BOMAG / Nd molar ratio of 2.2, and a pre-formed monomer, 1,3-butadiene with a 1,3-butadiene / Nd molar ratio of 90. The medium is heated to 80°C for 5 hours. It is prepared according to a preparation method as described in paragraph [number missing]. Petition 870260074934, dated 07 / 28 / 2026, pp. 30 / 37 19 / 22 II. 1 of patent application WO 2017093654 Al.

[0082] The microstructure of the El copolymer and its properties are shown in Tables 1 and 2. For the microstructure, Table 1 indicates the molar ratios of ethylene (Eth) units, 1,3-butadiene units, and 1,2-cyclohexanedi-yl (cyclo) motifs. TABLE 1 elastomer El ethylene (%mol) 68.6 butadiene 1,3 (%mol) 14.9 1,2-cyclohexanedi-yl (%mol) 8.5 TABLE 2 elastomer El Tg (°C) -43.4 Mn (g / mol) 157.700 Mooney (mL (1+4)) at 100°C 69.9 III-3 PREPARATION OF COMPOSITIONS

[0083] In the examples that follow, the rubber compounds were made as described in point II.5 above. In particular, the non-productive phase was carried out in a 0.4 liter mixer for 3.5 minutes, at an average paddle speed of 50 revolutions per minute until a maximum drop temperature of 160°C was reached. The productive phase was carried out in a cylinder tool at 23°C for 5 minutes.

[0084] The crosslinking of the composition was carried out at a temperature between 130°C and 200°C, under pressure. III-4 Rubber compound tests

[0085] The examples presented below are intended to compare the Petition 870260074934, dated 07 / 28 / 2026, pp. 31 / 37 20 / 22 performance compromise between the stretch-to-break and tear resistance of compositions according to the present invention (C1 to C3) with control compositions (T0 to T3).

[0086] Table 3 presents the compositions tested (in phr), as well as the results obtained.

[0087] The control compositions differ from the compositions (C1 to C3) by the nature of the butadiene-styrene based copolymer, by the nature of the natural rubber, by the reinforcement load rate.

[0088] The tensile strength at 60°C and tear strength results are expressed as a percentage on a 100 basis relative to the control compound T0, corresponding to a standard tread compound for heavy loads. A decrease of less than 10 from 10 to 100 in tear resistance is considered acceptable given the high performance of the T0 control compound. TABLE 3 Compositions T0 T1 C1 C2 T2 T3 C3 NR(1) 60 - 2.5 5 20 - 5 BR (2) 20 - - - - - SBR (3) 20 - - - - - Elastomer E1 (4) - 100 97.5 95 80 100 95 Carbon black (5) 55 40 40 40 40 12 12 Silica (6) 24 24 Silane (7) - - - - - 2 2 Paraffin 1 1 1 1 1 1 1 Antioxidant (8) 2 2 2 2 2 2 2 Polyethylene glycol (9) - 0.6 0.6 0.6 0.6 - Stearic acid (10) 1.5 1.5 1.5 1.5 1.5 1.5 1.5 Petition 870260074934, dated 07 / 28 / 2026, pages 32 / 37 21 / 22 ZnO(11) 2.5 2.5 2.5 2.5 2.5 2.5 2.5 Accelerator (12) 1 1 1 1 1 0.5 0.5 Sulfur 1 1 1 1 1 0.75 0.75 DPG(13) - - - - - 0.75 0.75 Properties Stretch at rupture (%) 100 121 115 110 74 121 130 Tear 100 132 110 93 17 101 97 (1) Natural rubber (2) 98% 1,4-Cis neodymium polybutadiene, Tg = -108°C (3) SBR tin-functionalized solution with 15% styrene and 24% 1,2-polybutadiene butadiene moieties (Tg = -65°C) (4) E1 elastomer prepared in point III-2 above (5) N234 grade carbon black according to ASTM D-1765 (6) Solvay Zeosil 1165MP silica (7) Momentive Mercapto-Thiocarboxylate silane oligomer (8) Flexsys N-1,3-dimethylbutyl-N-phenylparaphenylenediamine “Santoflex 6-PPD” (9) Dow Corning CARBOWAX 8000 polyethylene glycol (10) Pristerene 4931 stearic acid from Uniqema (11) Industrial grade zinc oxide from Umicore (12) Santocure CBS N-cyclohexyl-1-2-benzothiazyl sulfenamide from Flexsys (13) Perkacit DPG diphenylguanidine from Flexsys

[0089] The results presented in Table 3 above show that compositions comprising a copolymer containing ethylene units and 1,3-diene units as per the invention exhibit improved stretch-to-break strength without significantly impacting tear resistance when these compositions comprise less than 20 phr of polyisoprene, including a mass ratio of 1,4-cis linkages of at least 90%. Petition 870260074934, dated 07 / 28 / 2026, pp. 33 / 37 22 / 22

[0090] Additionally, fatigue resistance tests were performed on compositions T1 to T3 and C1 to C3 to compare the effect of the polyisoprene ratio on the durability of two formulations (Table 4).

[0091] Fatigue resistance results are expressed as a percentage on a basis of 100 relative to control composition T1 for compositions C1, C2 and T2, and relative to composition T3 for composition C3. TABLE 4 Compositions T1 C1 C2 T2 T3 C3 Properties Fatigue (MFTR) Base 100 100 112 138 53 100 149

[0092] The results presented in Table 4 above show that the presence of polyisoprene at the rates pertaining to the invention allows for improved fatigue resistance.

[0093] Thus, the compositions according to the invention exhibit a very good compromise of performance between stretch to rupture, tear resistance and fatigue resistance, and consequently better durability or longevity. Petition 870260074934, dated 07 / 28 / 2026, pp. 34 / 37

Claims

1 / 2 CLAIMS 1. Rubber composition characterized by being based on at least: - an elastomeric matrix comprising 85 to 98 phr of at least one copolymer containing ethylene units and 1,3-diene units, the molar fraction of the ethylene units in the copolymer being in a range from more than 50% to 95%, and 2 to 15 phr of a polyisoprene comprising a mass ratio of 1,4-cis linkages of at least 90% of the mass of the polyisoprene, - a reinforcing filler comprising carbon black having a specific BET surface area in a range from 50 to 160 m2 / g, and - a crosslinking system.

2. Rubber composition according to claim 1, characterized in that the copolymer containing ethylene units and 1,3-diene units is an ethylene-1,3-diene copolymer.

3. Rubber composition according to claim 1 or 2, characterized in that the 1,3-diene units are 1,3-butadiene units.

4. Rubber composition, according to any one of claims 1 to 3, characterized in that the copolymer does not contain a 1,3-diene unit of the formula CH2=CR-CH=CH2, wherein R represents a hydrocarbon chain having 3 to 20 carbon atoms.

5. Rubber composition, according to any one of claims 1 to 4, characterized in that the ratio of at least one copolymer containing ethylene units and 1,3-diene units is comprised in a range of 88 to 97 phr, preferably from more than 90 to 96 phr.

6. Rubber composition, according to any one of claims 1 to 5, characterized in that the polyisoprene is selected from the group consisting of natural rubber, synthetic polyisoprenes and mixtures thereof, preferably the polyisoprene is natural rubber.

7. Rubber composition, according to any one of claims 1 to 6, characterized in that the polyisoprene content is comprised in a range of 3 to 12 phr, preferably from 4 to less than 10 phr.

8. Rubber composition, according to any one of claims 1 to 7, characterized in that the carbon black has a specific surface area (BET) comprising a range of 90 to 160 m² / g, and preferably 100 to 150 m² / g.

9. Rubber composition, according to any one of claims 1 to 8, characterized in that the reinforcing filler comprises more than 50% by weight, preferably more than 90% by weight, of carbon black.

10. Rubber composition, according to any one of claims 1 to 8, characterized in that the reinforcing filler comprises 50% to 95% by weight, preferably 60% to 95% by weight, of silica and 5% to 50% by weight, preferably 5% to 40% by weight, of carbon black.

11. Rubber composition, according to any one of claims 1 to 10, characterized in that the reinforcing load ratio is comprised in a range of 20 to 70 phr, preferably 30 to 60 phr.

12. Rubber composition, according to any one of claims 1 to 11, characterized in that the crosslinking system is a molecular sulfur-based and / or sulfur-donating agent-based vulcanization system.

13. Rubber composition according to any one of claims 1 to 12, characterized in that the rubber composition does not comprise rubber granules.

14. Rubber composition, according to any one of claims 1 to 13, characterized in that the rubber composition does not comprise formaldehyde resin, preferably does not comprise reinforcing resin.

15. Heavyweight tire characterized by comprising a composition, as defined in any one of claims 1 to 14, the composition being present in the tire tread. Petition 870260074934, dated 07 / 28 / 2026, pp. 36 / 37