Tyre provided with an outer sidewall based on a composition containing pyrolysis carbon black

Abstract

The present invention relates to pneumatic tyres and more particularly to the outer sidewalls of tyres, i.e. by definition, to the elastomeric layers located radially on the outside of the tyre which are in contact with the ambient air.

Description

[0001] TYRE PROVIDED WITH AN EXTERNAL SIDEWALL BASED ON A COMPOSITION COMPRISING PYROLYSIS CARBON BLACK

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to pneumatic tires and more particularly to the external sidewalls of tires, that is to say, by definition, to the elastomeric layers located radially outside the tire, which are in contact with the ambient air.

[0004] TECHNOLOGICAL BACKGROUND

[0005] Within a tire, three zones are classically distinguished: the radially outer zone in contact with the ambient air; the radially inner zone in contact with the inflation gas; the internal zone of the tire.

[0006] The radially outer zone in contact with the ambient air is essentially made up of the tread and the outer sidewall of the tire. An outer sidewall is an elastomeric layer arranged outside the carcass reinforcement relative to the internal cavity of the tire, between the crown and the bead so as to totally or partially cover the area of ​​the carcass reinforcement extending from the crown to the bead.

[0007] The radially inner zone in contact with the inflation gas is generally constituted by the inflation gas-tight layer, sometimes called the inner liner.

[0008] The inner zone of the tire is the area between the outer and inner zones. This zone includes layers or plies that are referred to here as the inner layers of the tire. These are, for example, carcass plies, tread sub-layers, tire belt plies, or any other layer that is not in contact with the ambient air or the tire inflation gas.

[0009] It is important for the tire performance that the outer sidewall area has good rolling resistance performance. Good rolling resistance performance can be achieved by lowering the filler content of rubber compounds and by using silica predominantly. However, it has been observed that lowering the filler content in rubber compounds leads to processability problems of the compounds, in particular uncontrollable swelling of the compounds making them unsuitable for use in industrial equipment commonly used for tire manufacturing.

[0010] Thus, a need remains for the provision of compositions exhibiting both good processability and exhibiting good performance in the cured state, particularly in terms of rolling resistance, and which advantageously meet an increasingly present need to limit the environmental impact of the manufacture and use of tires.

[0011] BRIEF DESCRIPTION OF THE INVENTION

[0012] The present invention relates to a tire provided with an external sidewall, the external sidewall comprising at least one rubber composition based on:

[0013] - at least one elastomer;

[0014] - 16 to 20% by volume, relative to the total volume of the composition, of reinforcing fillers; and

[0015] - a crosslinking system; the reinforcing fillers comprising: from 6 to 16%, preferably from 6 to 11%, by volume, relative to the total volume of the composition, of reinforcing fillers selected from the group consisting of reinforcing inorganic fillers, carbon blacks having a CTAB specific surface area greater than or equal to 90 m 2 / g and mixtures of reinforcing inorganic fillers and carbon blacks having a CTAB specific surface area greater than or equal to 90 m 2 / g in which the reinforcing inorganic filler is the majority by mass; pyrolysis carbon blacks in sufficient quantity to achieve a volume of reinforcing fillers in the composition ranging from 16% to 20% relative to the total volume of the composition.

[0016] Other aspects of the invention are as described below and in the claims.

[0017] DEFINITIONS

[0018] The expression "composition based on" means a composition comprising the mixture and / or the in situ reaction product of the different constituents used, some of these constituents being able to react and / or being intended to react with each other, at least partially, during the different phases of manufacture of the composition; the composition can thus be in a totally or partially crosslinked state or in a non-crosslinked state.

[0019] By the expression "part by weight per hundred parts by weight of elastomer" (or pce), it is meant, within the meaning of the present invention, the part, by mass per hundred parts by mass of elastomer or rubber, the two terms being synonymous.

[0020] In this document, unless expressly stated otherwise, all percentages (%) indicated are percentages (%) by mass.

[0021] By "predominantly" or "in a majority capacity", it is meant, within the meaning of the present invention, that the compound is in the majority among the compounds of the same type in the composition, that is to say that it is the one which represents the largest quantity by mass among the compounds of the same type. In other words, the mass of this compound represents at least 51% of the total mass of the compounds of the same type in the composition. For example, in a system comprising a single elastomer, this is in the majority within the meaning of the present invention; and in a system comprising two elastomers, the majority elastomer represents more than half of the total mass of the elastomers, in other words the mass of this elastomer represents at least 51% of the total mass of the elastomers. In the same way, a so-called majority filler is that representing the largest mass among the fillers in the composition.In other words, the mass of this filler represents at least 51% of the total mass of fillers in the composition.

[0022] On the other hand, any interval of values ​​designated by the expression "between a and b" represents the range of values ​​from more than a to less than b (i.e., excluding the limits a and b), while any interval of values ​​designated by the expression "from a to b" means the range of values ​​from a to b (i.e., including the strict limits a and b). In this document, when describing an interval of values ​​by the expression "from a to b", the interval represented by the expression "between a and b" is also and preferably described.

[0023] The term "radial" refers to a radius of the tire. In this sense, a point P1 is said to be "radially inward" of a point P2 (or "radially inward" of point P2) if it is closer to the tire's axis of rotation than point P2. Conversely, a point P3 is said to be "radially outward" of a point P4 (or "radially outward" of point P4) if it is further from the tire's axis of rotation than point P4. We say that we are moving "radially inward (or outward)" when we are moving toward smaller (or larger) radii. When talking about radial distances, this meaning of the term also applies.

[0024] By "radial cut" or "radial section" is meant here a cut or section along a plane which contains the axis of rotation of the tire.

[0025] An “axial” direction is a direction parallel to the tire’s axis of rotation. A point P5 is said to be “axially inboard” of a point P6 (or “axially inboard” of point P6) if it is closer to the tire’s median plane than point P6. Conversely, a point P7 is said to be “axially outboard of” a point P8 (or “axially outboard” of point P8) if it is further from the tire’s median plane than point P8. The tire’s “median plane” is the plane that is perpendicular to the tire’s axis of rotation and is equidistant from the annular reinforcement structures of each bead.

[0026] A "circumferential" direction is a direction that is perpendicular to both a tire radius and the axial direction.

[0027] The carbon-containing compounds mentioned in the description may be of fossil or bio-sourced origin. In the latter case, they may be, partially or totally, derived from biomass or obtained from renewable raw materials derived from biomass. This includes, in particular, polymers, plasticizers, fillers, etc.

[0028] DETAILED DESCRIPTION OF THE INVENTION

[0029] The inventors have developed rubber compositions that meet the expressed needs. It has been demonstrated that the addition of pyrolysis carbon black to a rubber composition makes it possible to increase the filler content in the composition, and therefore to promote its processability, without penalizing the performance of the composition.

[0030] Thus, the present invention relates to a tire provided with an external sidewall, the external sidewall comprising at least one rubber composition based on:

[0031] - at least one elastomer;

[0032] - 16 to 20% by volume, relative to the total volume of the composition, of reinforcing fillers; and

[0033] - a crosslinking system; the reinforcing fillers comprising: from 6 to 16%, preferably from 6 to 11%, by volume, relative to the total volume of the composition, of reinforcing fillers selected from the group consisting of reinforcing inorganic fillers (preferably silica), carbon blacks having a CTAB specific surface area greater than or equal to 90 m 2 / g and mixtures of reinforcing inorganic fillers (preferably silica) and carbon blacks having a CTAB specific surface area greater than or equal to 90 m 2 / g in which the reinforcing inorganic filler (preferably silica) is the majority by mass; pyrolysis carbon blacks in sufficient quantity to achieve a volume of reinforcing fillers in the composition ranging from 16% to 20% relative to the total volume of the composition.

[0034] The rubber composition may further comprise customary additives and processing agents.

[0035] The various constituents of the rubber composition may be as described below.

[0036] Elastomer

[0037] The composition useful in the context of the present invention is based on at least one elastomer (or indistinctly rubber).

[0038] The elastomer may be chosen from the group consisting of diene elastomers and mixtures thereof.

[0039] By "diene" elastomer, whether natural or synthetic, is meant in a known manner an elastomer consisting at least in part (i.e., a homopolymer or a copolymer) of diene monomer units (monomers carrying two carbon-carbon double bonds, conjugated or not).

[0040] These diene elastomers can be classified into two categories: "essentially unsaturated" or "essentially saturated". "Essentially unsaturated" generally means a diene elastomer derived at least in part from conjugated diene monomers, having a content of units or patterns of diene origin (conjugated dienes) which is greater than 15% (mol %); thus, diene elastomers such as butyl rubbers or copolymers of dienes and alpha-olefins such as EPDM do not fall within the preceding definition and can be described in particular as "essentially saturated" diene elastomers (low or very low content of patterns of diene origin, always less than 15%).

[0041] The following are particularly understood to mean a diene elastomer which may be used: (a) - any homopolymer obtained by polymerization of a diene monomer, conjugated or not, having from 4 to 18 carbon atoms;

[0042] (b) - any copolymer obtained by copolymerization of a diene, conjugated or not, having from 4 to 18 carbon atoms and at least one other monomer.

[0043] The other monomer can be ethylene, an olefin or a diene, conjugated or not.

[0044] Suitable conjugated dienes are conjugated dienes having 4 to 12 carbon atoms, in particular 1,3-dienes, such as 1,3-butadiene and isoprene.

[0045] Suitable olefins are vinylaromatic compounds with 8 to 20 carbon atoms and aliphatic α-monoolefins with 3 to 12 carbon atoms.

[0046] Suitable vinyl aromatic compounds are, for example, styrene, ortho-, meta-, para-methylstyrene, the commercial mixture "vinyl-toluene", para-tert-butylstyrene. Suitable aliphatic α-monoolefins are, in particular, acyclic aliphatic α-monoolefins having from 3 to 18 carbon atoms.

[0047] More particularly, the diene elastomer capable of being used in the compositions can be:

[0048] (a') - any homopolymer obtained by polymerization of a conjugated diene monomer having from 4 to 12 carbon atoms;

[0049] (b') - any copolymer obtained by copolymerization of one or more conjugated dienes with each other or with one or more vinylaromatic compounds having from 8 to 20 carbon atoms;

[0050] (c') - any copolymer obtained by copolymerization of one or more dienes, conjugated or not, with ethylene, an α-monoolefin or their mixture, such as for example elastomers obtained from ethylene, propylene with a non-conjugated diene monomer of the aforementioned type.

[0051] Preferably, the diene elastomer is chosen from the group consisting of polybutadienes (BR), natural rubber (NR), synthetic polyisoprenes (IR), butadiene copolymers, isoprene copolymers, and blends of these elastomers. Butadiene copolymers are particularly chosen from the group consisting of butadiene-styrene copolymers (SBR).

[0052] The diene elastomer can be modified, i.e. either coupled and / or star-shaped, or functionalized, or coupled and / or star-shaped and simultaneously functionalized.

[0053] Thus, the diene elastomer can be coupled and / or star-shaped, for example by means of a silicon or tin atom which links the elastomer chains together. The diene elastomer can be simultaneously or alternatively functionalized and comprise at least one functional group. By functional group is meant a group comprising at least one heteroatom chosen from Si, N, S, O, P. Particularly suitable as functional groups are those comprising at least one function such as: silanol, an alkoxysilane, a primary, secondary or tertiary amine, cyclic or not, a thiol, an epoxide.

[0054] The rubber composition useful in the context of the invention may contain a single diene elastomer or a mixture of several diene elastomers.

[0055] In certain embodiments, the rubber composition useful in the context of the invention comprises one or more elastomers; it may thus comprise from 25 to 100 phr of natural rubber and from 0 to 75 phr of at least one polybutadiene, preferably from 35 to 75 phr of natural rubber and from 25 to 65 phr of at least polybutadiene.

[0056] In certain embodiments, the rubber composition useful in the context of the invention comprises, as elastomer, a mixture of natural rubber (NR) and at least one polybutadiene (BR). Preferably, the mixture consists of 50 phr of natural rubber (NR) and 50 phr of polybutadiene (BR).

[0057] The composition useful in the context of the present invention comprises reinforcing fillers. The reinforcing fillers represent from 16 to 20% by volume of the total volume of the composition.

[0058] The term "reinforcing filler" commonly refers to any type of filler known for its ability to reinforce a rubber composition that can be used in particular for the manufacture of tires, for example organic fillers such as carbon black or pyrolysis carbon black, or inorganic fillers such as silica or alumina.

[0059] The composition useful in the context of the present invention comprises: from 6 to 16%, preferably from 6 to 11%, by volume, relative to the total volume of the composition, of reinforcing fillers selected from the group consisting of reinforcing inorganic fillers (preferably silica), carbon blacks having a CTAB specific surface area greater than or equal to 90 m 2 / g and mixtures of reinforcing inorganic fillers (preferably silica) and carbon blacks having a CTAB specific surface area greater than or equal to 90 m 2 / g in which the reinforcing inorganic filler (preferably silica) is the majority by mass; pyrolysis carbon blacks in sufficient quantity to achieve a volume of reinforcing fillers in the composition ranging from 16% to 20% relative to the total volume of the composition.

[0060] In certain embodiments, the composition useful in the context of the present invention comprises: from 6 to 16%, preferably from 6 to 11%, by volume, relative to the total volume of the composition, of reinforcing fillers selected from the group consisting of reinforcing inorganic fillers (preferably silica) and mixtures of reinforcing inorganic fillers (preferably silica) and carbon blacks having a CTAB specific surface area greater than or equal to 90 m 2 / g in which the reinforcing inorganic filler (preferably silica) is the majority by mass; pyrolysis carbon blacks in sufficient quantity to achieve a volume of reinforcing fillers in the composition ranging from 16% to 20% relative to the total volume of the composition.

[0061] Typically, mixtures of inorganic fillers (preferably silica) and carbon blacks having a CTAB specific surface area greater than or equal to 90 m 2 / g in which the inorganic filler is the majority by mass include 10 volumes of inorganic fillers for 2 to 3 volumes of carbon blacks.

[0062] The CTAB specific surface area of ​​carbon blacks is determined according to ASTM D3765-03a published in December 2003.

[0063] The reinforcing fillers may be as described below.

[0064] Pyrolysis carbon black

[0065] For the purposes of the present invention, the term "pyrolysis carbon black" means a carbon black resulting from a process for the pyrolysis of a material comprising at least one carbon polymer and one carbon black, hereinafter the material to be pyrolyzed, for example in the context of the recycling of such a material. The physical state in which the material to be pyrolyzed is present is indifferent, whether in the form of powder, granules, strips, or any other form, in a crosslinked or non-crosslinked state.

[0066] Preferably, the material to be pyrolyzed may be recovered from manufactured articles or products generated during their manufacture / production (such as by-products or scraps); these manufactured articles may be chosen from the group consisting of pneumatic tires, non-pneumatic tires, industrial conveyor belts, transmission belts, rubber seals, rubber hoses, shoe soles and windshield wipers. Even more preferably, the pyrolysis carbon black that can be used in the context of the present invention is a carbon black obtained from a pyrolysis process in which the material to be pyrolyzed is derived from manufactured articles chosen from the group consisting of pneumatic tires and non-pneumatic tires.

[0067] Pyrolysis in the context of the present invention means any type of thermal decomposition in the absence of oxygen and whose raw material is the material to be pyrolyzed as defined above. Pyrolysis carbon blacks are therefore distinguished from so-called industrial and / or ASTM grade carbon blacks in that the carbon raw material used for pyrolysis is a material comprising at least one carbon polymer and one carbon black and not materials derived from petroleum fractions or from coal or from oils of natural origin.

[0068] The pyrolysis carbon blacks that can be used in the context of the present invention are distinguished from known carbon blacks such as industrial carbon blacks, in particular so-called “furnace” carbon blacks, in particular by a higher ash content.

[0069] Preferably, the pyrolysis carbon black usable in the context of the present invention has an ash content within a range from 5 to 30% by weight, more preferably from 8 to 25% by weight, more preferably still from 10% to 22% by weight, relative to the total weight of the pyrolysis carbon black.

[0070] Preferably, the pyrolysis carbon black usable in the context of the present invention has a sulfur content greater than 2% by weight, preferably 2.5 to 5% by weight, relative to the total weight of the pyrolysis carbon black.

[0071] Preferably, the pyrolysis carbon black usable in the context of the present invention has a zinc content greater than or equal to 2% by weight, preferably 2.5 to 8% by weight, relative to the total weight of the pyrolysis carbon black. Preferably, the pyrolysis carbon black usable in the context of the present invention has a specific surface area STSA measured according to the ASTM D 6556-2021 standard within a range from 20 to 200 m 2 / g, more preferably ranging from 30 to 90 m 2 / g.

[0072] Preferably, the pyrolysis carbon black usable in the context of the present invention has a void volume measured according to standard ASTM D7854-21 and at a pressure of 50 MPa within a range from 30 to 60 ml / 100g, more preferably from 35 to 55 ml / 100g.

[0073] The ash content is determined by calcination in platinum capsules in a muffle furnace at 825°C according to the following protocol. A capsule is previously identified before each series of measurements and is tared to the nearest 0.1 mg and the mass is noted PO. In the capsule, 5 g of pyrolysis carbon black sample is introduced and weighed precisely to the nearest 0.1 mg; this mass is noted P1. The capsule and its contents are pre-calcined using a Bunsen burner until fumes appear and the product ignites. Once the product has completely burned, the capsule and its contents are introduced into a muffle furnace heated to 825 C for 1 h. After 1 h, the capsule is removed from the furnace and immediately placed in a desiccator at room temperature. When the capsule and the ash have returned to room temperature, the capsule is weighed again to obtain the mass P2.Finally, it is possible to obtain the ash content (% ash) using the formula below:.

[0074] % ... ash 100

[0075] The zinc content in the pyrolysis carbon black is determined after calcination of the sample, then recovery of the ashes in an acid medium and determination by ICP-AES (inductively coupled plasma atomic emission spectroscopy). The ashes are obtained by carrying out the protocol above. Approximately 100 mg of ashes (test sample) are taken and placed in a PFA (perfluoroalkoxy) tube for a HotBIock hot plate. 8 mL of 37% concentrated hydrochloric acid, 3 mL of 65% concentrated nitric acid and 0.5 mL of 40% hydrofluoric acid are then added. The tube is closed with its cap and heated at 130 C for 2 h. After cooling, the contents are then transferred using ultrapure water into a 100 mL PTFE (polytetrafluoroethylene) volumetric flask already containing 2 g of boric acid (to neutralize the hydrofluoric acid). The volume is topped up with ultrapure water to the fill line.The solution obtained is diluted by 100, by taking 1 mL in a 100 mL PFTE flask, previously containing 8 mL of 37% concentrated hydrochloric acid, 3 mL of 65% concentrated nitric acid, 0.5 mL of 40% hydrofluoric acid and 2 g of boric acid. This diluted solution is then filtered through a 0.45 pm GHP syringe filter before being analyzed by inductively coupled plasma atomic emission spectrometry (ICP-AES). Before analyzing the diluted solution, at least 5 standards are analyzed by ICP-AES at zinc concentrations of 0, 0.5, 1, 2 and 5 mg / L. These standards were prepared in 100 mL volumetric flasks, by diluting a certified commercial solution to a zinc concentration of 1 g / L.

[0076] These volumetric flasks contain 8 mL of 37% concentrated hydrochloric acid, 3 mL of 65% concentrated nitric acid, 0.5 mL of 40% hydrofluoric acid and 2 g of boric acid. The standard solutions are analyzed by ICP-AES at a wavelength of λZn = 202.613 nm. For each standard concentration (c), the zinc signal intensity IZn is plotted on a graph IZn = f(c), which corresponds to the calibration line (of type y = ax + b). The sample solution (diluted solution) of unknown concentration is then measured under the same conditions as the standards. The measured intensity is related to the concentration using the calibration line obtained previously. The concentration [c]ash in % by mass is thus obtained directly by the software, because the test portion and the volume have been previously recorded. The zinc concentration in pyrolysis black [c]black in mass % is obtained by the following equation: ashes

[0077] The determination of the sulfur content in pyrolysis carbon blacks is carried out by LECO furnace. LECO sulfur analyzers are designed to measure, in particular, the sulfur content in organic and / or inorganic materials by combustion and non-dispersive infrared detection. Before measuring the sulfur content on the sample, the boats are cleaned and the furnace calibrated. The boats for LECO furnaces are previously cleaned: this involves analyzing the empty boat, under the same conditions as the samples. The preparation of the calibration curve is done from a commercial standard called "BBOT" whose purity is greater than 99.99% and whose carbon (C), hydrogen (H), nitrogen (N), oxygen (O) and sulfur (S) content is guaranteed. This content is as follows: C%: 72.52; H% 6.09; N% 6.51; 0% 7.43 and S% 7.44. Approximately 10 ± 3, 20 ± 3 and 40 ± 3 mg of BBOT are weighed exactly in a pod.The standard / boat assembly is introduced into the combustion furnace, regulated at 1350 C under pure oxygen. The combination of the furnace temperature and the analysis flow rate causes the combustion of the sample and the release of sulfur and / or carbon in the form of SC>2(g). After a time of 20 s, oxygen begins to flow through the "lance" to accelerate the combustion of difficult-to-burn materials. The sulfur and / or carbon, in the form of SC>2(g), are carried by an oxygen flow through the infrared detection cells. The instrument software draws a straight line connecting the mass of standard introduced and the observed response (area) on the detector. This gives a calibration straight line. After carefully cleaning the sampling equipment, approximately 80 ± 5 mg of pyrolysis carbon black is weighed and introduced into a LECO tower boat.The observed SO2 peak area is related to the concentration using the calibration line. The instrument software then calculates the mass % of sulfur in the sample using the mass of the sample introduced into the basket.

[0078] Pyrolysis carbon blacks are marketed, for example, by the company BlackBear under the reference “BBCT30” or by the company Scandinavian Enviro Systems under the reference “P550”.

[0079] Carbon black

[0080] All carbon blacks are suitable as carbon blacks, including blacks conventionally used in tires or their treads, in particular industrial carbon blacks, more specifically so-called "furnace" carbon blacks.

[0081] Among carbon blacks having a CTAB specific surface area greater than or equal to 90 m 2 / g, we will mention more particularly the reinforcing carbon blacks of the 100 and 200 series, such as for example blacks N115, N 134 and N234 (grades ASTM D-1765-2017). The carbon blacks can be used in the isolated state, as commercially available, or in any other form, for example as a support for some of the rubber additives used. The carbon blacks could for example already be incorporated into the diene elastomer, in particular isoprene in the form of a masterbatch (see for example applications WO 97 / 36724-A2 or WO 99 / 16600-A1). Reinforcing inorganic filler

[0082] By "reinforcing inorganic filler" is meant here any inorganic or mineral filler, whatever its color and origin (natural or synthetic), also called "white" filler, "clear" filler or even "non-black" filler as opposed to carbon black, capable of reinforcing on its own, without any other means than an intermediate coupling agent, a rubber composition intended for the manufacture of tires. As is known, certain reinforcing inorganic fillers can be characterized in particular by the presence of hydroxyl groups (-OH) on their surface.

[0083] Suitable reinforcing inorganic fillers are, in particular, mineral fillers of the siliceous type, preferably silica (SiC>2) or of the aluminous type, in particular alumina (AI2O3). The silica used may be any reinforcing silica known to those skilled in the art, in particular any precipitated or pyrogenic silica having a BET specific surface area and a CTAB specific surface area, both of less than 450 m 2 / g, preferably within a range of 30 to 400 m 2 / g, especially from 60 to 300 m 2 / g.

[0084] Any type of precipitated silica can be used, in particular highly dispersible precipitated silicas (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 WO 03 / 016215-A1 and WO 03 / 016387-A1. Among the commercial HDS silicas, it is possible to use in particular the silicas "Ultrasil ® 5000GR", "Ultrasil ® 7000GR" from the company Evonik, the silicas "Zeosil ® 1085GR", "Zeosil® 1115 MP", "Zeosil® 1165MP", "Zeosil® Premium 200MP", "Zeosil® HRS 1200 MP" from the company Solvay.As non-HDS silica, the following commercial silicas can be used: silicas “Ultrasil ® VN2GR”, “Ultrasil ® VN3GR” from Evonik, silica “Zeosil® 175GR” from Solvay, silicas “Hi-Sil EZ120G(-D)”, “Hi-Sil EZ160G(- D)”, “Hi-Sil EZ200G(-D)”, “Hi-Sil 243LD”, “Hi-Sil 210”, “Hi-Sil HDP 320G” from PPG.

[0085] The BET specific surface area of ​​silica is determined in a known manner by gas adsorption using the Brunauer-Emmett-Teller method described in "The Journal of the American Chemical Society" Vol. 60, page 309, February 1938, more precisely according to the French standard NF ISO 9277 of December 1996 (multipoint volumetric method (5 points) - gas: nitrogen - degassing: 1 hour at 160°C - relative pressure range p / po: 0.05 to 0.17). The CTAB specific surface area of ​​silica is determined according to the French standard NF T 45-007 of November 1987 (method B).

[0086] As other examples of inorganic fillers that may be used in the compositions, mention may also be made of mineral fillers of the aluminous type, in particular alumina (AI2O3), aluminum oxides, aluminum hydroxides, aluminosilicates, titanium oxides, silicon carbides or nitrides, all of the reinforcing type as described, for example, in applications WO 99 / 28376-A2, WO 00 / 73372-A1, WO 02 / 053634-A1, WO 2004 / 003067-A1, WO 2004 / 056915-A2, US 6,610,261-B1 and US 6,747,087-B2. Examples include "Baikalox A125" or "CR125" aluminas (Baïkowski company), "APA-100RDX" (Condéa), "Aluminoxid C" (Evonik) or "AKP-G015" (Sumitomo Chemicals). While kaolin is composed primarily of aluminosilicates, it is well known to those skilled in the art that kaolin is not a reinforcing filler.

[0087] The physical state in which the reinforcing inorganic filler is presented is indifferent, whether in the form of powder, microbeads, granules, or even beads or any other suitable densified form. Of course, the term reinforcing inorganic filler also means mixtures of different reinforcing inorganic fillers, in particular silicas as described above.

[0088] Those skilled in the art will understand that, as a replacement for the reinforcing inorganic filler described above, a reinforcing filler of another nature could be used, provided that this reinforcing filler of another nature is covered with an inorganic layer such as silica, or else has functional sites on its surface, in particular hydroxyl sites, requiring the use of a coupling agent to establish the bond between this reinforcing filler and the diene elastomer. By way of example, mention may be made of carbon blacks partially or completely covered with silica, or carbon blacks modified with silica, such as, without limitation, the “Ecoblack®” type fillers of the CRX2000 series or the “CRX4000” series from Cabot Corporation.

[0089] The person skilled in the art will be able to adapt the total rate of reinforcing charge according to the use concerned, in particular according to the type of tire concerned, for example a tire for a motorcycle, for a passenger vehicle or even for a utility vehicle such as a van or heavy goods vehicle.

[0090] To couple the reinforcing inorganic filler to the diene elastomer, it is possible to use, in a well-known manner, an at least bifunctional coupling agent (or bonding agent) intended to ensure a sufficient connection, of a chemical and / or physical nature, between the inorganic filler (surface of its particles) and the diene elastomer. In particular, at least bifunctional organosilanes or polyorganosiloxanes are used. By "bifunctional", we mean a compound having 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 a bifunctional compound may comprise a first functional group comprising a silicon atom, said first functional group being capable of interacting with the hydroxyl groups of an inorganic filler and a second functional group comprising a sulfur atom, said second functional group being capable of interacting with the diene elastomer.

[0091] Preferably, the organosilanes are chosen from the group consisting of polysulfurized organosilanes (symmetrical or asymmetrical) such as bis(3-triethoxysilylpropyl) tetrasulfide, abbreviated to TESPT, marketed under the name “Si69” by the company Evonik or bis-(triethoxysilylpropyl) disulfide, abbreviated to TESPD, marketed under the name “Si75” by the company Evonik, polyorganosiloxanes, mercaptosilanes, blocked mercaptosilanes, such as S-(3-(triethoxysilyl)propyl) octanethioate marketed by the company Momentive under the name “NXT Silane”. More preferably, the organosilane is a polysulfurized organosilane.

[0092] The skilled person can find examples of coupling agent in the following documents: WO 02 / 083782, WO 02 / 30939, WO 02 / 31041, WO 2007 / 061550, WO 2006 / 125532, WO 2006 / 125533, WO 2006 / 125534, US 6,849,754, WO 99 / 09036, WO 2006 / 023815, WO 2007 / 098080, WO 2010 / 072685 and WO 2008 / 055986.

[0093] The coupling agent content preferably represents from 0.5% to 15% by weight relative to the amount of reinforcing inorganic filler, preferably from 4 to 12%, more preferably from 6 to 10% by weight relative to the amount of reinforcing inorganic filler. Typically, the coupling agent level is less than 20 phr, preferably within a range from 6 to 17 phr, preferably from 8 to 15 phr. This level can easily be adjusted by a person skilled in the art according to the level of inorganic filler used in the composition.

[0094] The composition may also contain, in addition to the coupling agents, coupling activators, agents for covering inorganic fillers or more generally processing aids capable, in a known manner, thanks to an improvement in the dispersion of the filler in the rubber matrix and a reduction in the viscosity of the compositions, of improving their processability in the raw state, these agents being, for example, hydrolyzable silanes such as alkylalkoxysilanes (in particular alkyltriethoxysilanes), polyols, polyethers (for example polyethylene glycols), primary, secondary or tertiary amines (for example trialkanol-amines), hydroxylated or hydrolyzable POS, for example α,co-dihydroxy-polyorganosiloxanes (in particular α,co-dihydroxy-polydimethylsiloxanes), fatty acids such as, for example, stearic acid.

[0095] Crosslinking system

[0096] The composition useful in the context of the invention comprises a crosslinking system.

[0097] The crosslinking system may be any type of system known to those skilled in the art in the field of tire rubber compositions. It may in particular be based on sulfur, and / or peroxide and / or bismaleimides.

[0098] Preferably, the crosslinking system is sulfur-based, in which case it is referred to as a vulcanization system. The sulfur can be provided in any form, in particular in the form of molecular sulfur, or a sulfur-donating agent. At least one vulcanization accelerator is also preferably present, and, optionally, also preferably, various known vulcanization activators can be used, such as zinc oxide, stearic acid or equivalent compounds such as stearic acid salts and transition metal salts, guanidine derivatives (in particular diphenylguanidine), or even known vulcanization retarders.

[0099] Sulfur is used at a preferential rate of between 0.5 and 10 pce, particularly between 1 and 5 pce. The vulcanization accelerator is used at a preferential rate of between 0.5 and 10 pce, more preferably between 0.5 and 5.0 pce.

[0100] Any compound capable of acting as an accelerator for the vulcanization of diene elastomers in the presence of sulfur may be used as an accelerator, in particular accelerators of the thiazole type and their derivatives, accelerators of the sulfenamide, thiuram, dithiocarbamate, dithiophosphate, thiourea and xanthate types. Examples of such accelerators include, but are not limited to, the following compounds: 2-mercaptobenzothiazyl disulfide (abbreviated as "MBTS"), N-cyclohexyl-2-benzothiazyl sulfenamide ("CBS"), N,N-dicyclohexyl-2-benzothiazyl sulfenamide ("DCBS"), N-tert-butyl-2-benzothiazyl sulfenamide ("TBBS"), N-tert-butyl-2-benzothiazyl sulfenimide ("TBSI"), tetrabenzylthiuram disulfide ("TBZTD"), zinc dibenzyldithiocarbamate ("ZBEC") and mixtures of these compounds. Common additives and processing agents

[0101] The composition useful in the context of the invention may also comprise all or part of the usual additives and processing agents, known to those skilled in the art and usually used in rubber compositions for tires, in particular in compositions intended for the manufacture of external sidewalls of tires, such as for example plasticizers (such as plasticizing oils and / or plasticizing resins having or not a tackifying character), non-reinforcing fillers, pigments, protective agents such as anti-ozone waxes, chemical antiozonants, antioxidants, anti-fatigue agents, reinforcing resins (as described for example in application WO 02 / 10269).

[0102] In certain embodiments, the composition useful in the context of the invention comprises a plasticizer. The plasticizer content is then greater than 0 and less than or equal to 10 phr, for example from 1 to 5 phr.

[0103] The plasticizer is preferably chosen from hydrocarbon resins, plasticizing oils, and mixtures thereof.

[0104] Particularly suitable are plasticizing oils chosen from the group consisting of naphthenic oils (low or high viscosity, in particular hydrogenated or not), paraffinic oils, MES oils (Medium Extracted Solvates), TDAE oils (Treated Distillate Aromatic Extracts), RAE oils (Residual Aromatic Extract oils), TRAE oils (Treated Residual Aromatic Extract) and SRAE oils (Safety Residual Aromatic Extract oils), mineral oils, vegetable oils, ether plasticizers, ester plasticizers, phosphate plasticizers, sulfonate plasticizers and mixtures of these compounds.

[0105] Hydrocarbon resins, also called hydrocarbon plasticizing resins, are polymers well known to those skilled in the art, essentially based on carbon and hydrogen but which may contain other types of atoms, for example oxygen, which can be used in particular as plasticizing agents or tackifying agents in polymer matrices. They are by nature at least partially miscible (i.e., compatible) at the rates used with the polymer compositions for which they are intended, so as to act as true diluting agents. They have been described for example in the work entitled "Hydrocarbon Resins" by R. Mildenberg, M. Zander and G. Collin (New York, VCH, 1997, ISBN 3-527-28617-9) of which chapter 5 is devoted to their applications, in particular in pneumatic rubber (5.5. "Rubber Tires and Mechanical Goods").As is known, these hydrocarbon resins can also be described as thermoplastic resins in the sense that they soften upon heating and can thus be molded.

[0106] The softening point of hydrocarbon resins is measured according to ISO 4625 ("Ring and Bail" method). The Tg is measured according to ASTM D3418 (1999). The macrostructure (Mw, Mn and Ip) of the hydrocarbon resin is determined by size exclusion chromatography (SEC): tetrahydrofuran solvent; temperature 35°C; concentration 1 g / l; flow rate 1 ml / min; solution filtered through a 0.45 pm porosity filter before injection; Moore calibration with polystyrene standards; set of 3 "WATERS" columns in series ("STYRAGEL" HR4E, HR1 and HR0.5); detection by differential refractometer ("WATERS 2410") and its associated operating software ("WATERS EMPOWER").

[0107] Hydrocarbon resins can be aliphatic, aromatic, or aliphatic / aromatic, i.e., based on aliphatic and / or aromatic monomers. They can be natural or synthetic, petroleum-based or not (if so, also known as petroleum resins).

[0108] Suitable aromatic monomers include, for example, styrene, alpha-methylstyrene, indene, ortho-, meta-, para-methylstyrene, vinyl toluene, para-tert-butylstyrene, methoxystyrenes, chlorostyrenes, vinylmesitylene, divinylbenzene, vinylnaphthalene, any vinylaromatic monomer derived from a C9 fraction (or more generally from a C8 to C10 fraction). Preferably, the vinylaromatic monomer is styrene or a vinylaromatic monomer derived from a C9 fraction (or more generally from a C8 to C10 fraction). Preferably, the vinylaromatic monomer is the minority monomer, expressed as a molar fraction, in the copolymer under consideration.

[0109] According to a particularly preferred embodiment, the hydrocarbon plasticizing resin is chosen from the group consisting of cyclopentadiene (abbreviated CPD) or dicyclopentadiene (abbreviated DCPD) homopolymer or copolymer resins, terpene homopolymer or copolymer resins, terpene phenol homopolymer or copolymer resins, 05-cut homopolymer or copolymer resins, 09-cut homopolymer or copolymer resins, alpha-methyl-styrene homopolymer and copolymer resins and mixtures of these resins.

[0110] The term "terpene" here covers, in a known manner, the monomers alpha-pinene, beta-pinene and limonene; the limonene monomer being present, in a known manner, in the form of three possible isomers: L-limonene (levorotatory enantiomer), D-limonene (dextrorotatory enantiomer), or dipentene, the racemate of the dextrorotatory and levorotatory enantiomers. Among the above hydrocarbon plasticizing resins, mention will be made in particular of homo- or copolymer resins of alphapinene, betapinene, dipentene or polylimonene.

[0111] As is known, high Tg hydrocarbon resins are thermoplastic hydrocarbon resins with a Tg greater than 20°C.

[0112] Preferably, the plasticizing resin is a high Tg hydrocarbon plasticizing resin having at least one of the following characteristics: a Tg greater than 30°C; a number-average molecular mass (Mn) of between 300 and 2000 g / mol, more preferably between 400 and 1500 g / mol; a polymolecularity index (Ip) of less than 3, more preferably less than 2 (reminder: Ip = Mw / Mn with Mw weight-average molecular mass).

[0113] More preferably, this high Tg hydrocarbon plasticizing resin has all of the above preferred characteristics.

[0114] The above preferred high Tg hydrocarbon resins are well known to those skilled in the art and commercially available, for example sold with regard to: polylimonene resins: by the company DRT under the name "Dercolyte L120" (Mn=625 g / mol; Mw=1010 g / mol; lp=1.6; Tg=72°C) or by the company ARIZONA under the name "Sylvagum TR7125C" (Mn=630 g / mol; Mw=950 g / mol; lp=1.5; Tg=70°C); C5 cut / vinylaromatic copolymer resins, in particular O5 cut / styrene or O5 cut / C9 cut: by Neville Chemical Company under the names "Super Nevtac 78", "Super Nevtac 85" or "Super Nevtac 99", by Goodyear Chemicals under the name "Wingtack Extra", by Kolon under the names "Hikorez T1095" and "Hikorez T1100", by Exxon under the names "Escorez 2101" and "Escorez 1273";limonene / styrene copolymer resins: by DRT under the name "Dercolyte TS 105" from DRT, by ARIZONA Chemical Company under the names "ZT 115LT" and "ZT5100".;

[0115] Examples of other preferred resins include phenol-modified alpha-methyl-styrene resins. To characterize these phenol-modified resins, it is recalled that a so-called "hydroxyl index" (measured according to ISO 4326 standard and expressed in mg KOH / g) is used in a known manner. Alpha-methyl-styrene resins, in particular phenol-modified ones, are well known to those skilled in the art and are commercially available, for example sold by Arizona Chemical under the names "Sylvares SA 100" (Mn = 660 g / mol; Ip = 1.5; Tg = 53°C); "Sylvares SA 120" (Mn = 1030 g / mol; Ip = 1.9; Tg = 64°C); "Sylvares 540" (Mn = 620 g / mol; Ip = 1.3; Tg = 36°C; hydroxyl number = 56 mg KOH / g); "Sylvares 600" (Mn = 850 g / mol; Ip = 1.4; Tg = 50°C; hydroxyl number = 31 mg KOH / g).

[0116] We can also mention resins from the alkyl-phenol family such as octylphenyl formaldehyde (OPF) available for example under the name “SP 1068” from the company SI Group as well as gem rosin resins such as those supplied for example by the company Costa Irmaos.

[0117] Production of compositions

[0118] The rubber composition useful in the context of the invention is manufactured in suitable mixers, using two successive preparation phases well known to those skilled in the art:

[0119] - a first phase of working or thermomechanical mixing (so-called "non-productive" phase), which can be carried out in a single thermomechanical step during which all the necessary constituents, in particular the elastomeric matrix, the fillers, any other various additives, with the exception of the crosslinking system, are introduced into a suitable mixer such as a conventional internal mixer (for example of the 'Banbury' type). The incorporation of the filler into the elastomer can be carried out in one or more stages by thermomechanical mixing.In the case where the filler is already incorporated in whole or in part 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 which is directly mixed and where appropriate the other elastomers or fillers present in the composition which are not in the form of a masterbatch are incorporated, as well as any other various additives other than the crosslinking system.

[0120] The non-productive phase is carried out at high temperature, up to a maximum temperature of between 130°C and 170°C, for a duration generally of between 2 and 10 minutes. a second phase of mechanical work (so-called "productive" phase), which is carried out in an external mixer such as a roller mixer, after cooling the mixture obtained during the first non-productive phase to a lower temperature, typically below 110°C, for example between 40°C and 100°C. The crosslinking system is then incorporated, and everything is then mixed for a few minutes, for example between 1 and 30 min.

[0121] The final composition thus obtained is then calendered, for example, in the form of a sheet or plate, in particular for characterization in the laboratory, or extruded in the form of a semi-finished (or profiled) rubber usable, for example, as an internal layer in a tire.

[0122] The composition can be either in the raw state (before crosslinking or vulcanization), or in the cooked state (after crosslinking or vulcanization), can be a semi-finished product which can be used in a tire.

[0123] 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, preferably under pressure, for a sufficient time which can vary for example between 5 and 90 min. The examples which follow are given for illustrative purposes, but should in no case be considered as limiting the present invention.

[0124] TIRES

[0125] The tire according to the invention is intended to equip motor vehicles of the passenger car, SUV ("Sport Utility Vehicles") type, or two-wheeled vehicles (particularly motorcycles), or airplanes, or even industrial vehicles chosen from vans, "Heavy Goods Vehicles", - that is to say metro, bus, road transport vehicles (trucks, tractors, trailers), off-road vehicles such as agricultural or civil engineering vehicles -, and others. Preferably, the tire according to the invention is particularly suitable for equipping passenger car, van and SUV type vehicles.

[0126] The following examples are given for illustrative purposes. They should in no way be considered as limiting the present invention. EXAMPLES ues:

[0127] The dynamic properties, in particular G*10% return to 60°C and G”10% return to 60°C, representing respectively the rigidity and the hysteresis, are measured on a viscoanalyzer (Metravib VA4000), according to the ASTM D 5992-96 standard. The response of a sample of the vulcanized composition (cylindrical specimens of 4 mm thickness and 400 mm2 of section), subjected to a sinusoidal stress in alternating simple shear, at the frequency of 1000 Hz, at a temperature of 60°C is recorded.

[0128] For the measurements of dynamic complex shear modulus (G*) and loss factor (G”), a strain amplitude sweep is performed from 0.1% to 100% peak-peak (forward cycle), then from 100% to 0.1% peak-peak (return cycle). For the return cycle, the observed value of G”10% is indicated, as well as the G* modulus at 10% strain noted G*10%.

[0129] The results are expressed on a basis of 100 relative to the control (the value of 100 is given to the control).

[0130] Tensile Tests:

[0131] These tensile tests are used to determine the yield stresses and breaking properties. Unless otherwise stated, they are carried out in accordance with French standard NF T 46-002.

[0132] A treatment of the tensile recordings makes it possible in particular to plot the modulus curve as a function of the elongation. The modulus used here is the nominal (or apparent) secant modulus measured at first elongation, calculated by reducing it to the initial section of the specimen. The nominal secant modulus (or apparent stress, in MPa) is measured at first elongation at 10% and 300% elongation, noted respectively as MSA10 and MSA300.

[0133] The deformations at break and the tear energy at 23°C and 100°C+ / -2°C are also measured, according to the NFT 46-002 standard, on samples cooked for 50 min at 140°C.

[0134] The results are expressed on a basis of 100 relative to the control (the value of 100 is given to the control). Tearability

[0135] Tensile tests are used to determine the elastic moduli and breaking properties and are based on the NF ISO 37 standard of December 2005.

[0136] The tearability indices are measured at 23°C. In particular, the force required to achieve rupture (in N / mm) is determined and the strain at rupture (in %) is measured on a test piece measuring 10 x 85 x 2.5 mm, notched in the center of its length by 3 notches to a depth of 5 mm, to cause the specimen to rupture. This allows the energy required to cause rupture of the specimen to be determined, which is the product of the rupture force and the rupture strain. The results are given on a base of 100, i.e. the values ​​are expressed relative to a control, the measured value of which is considered as the reference at 100.

[0137] Thus, a lower value of the breaking energy represents a decrease in tear resistance performance (i.e., a decrease in breaking energy), while a higher value represents better performance.

[0138] Swelling index

[0139] The swelling index is determined using a rheometer, RHEOGRAPH 75, equipped with a camera system (i2S Company, reference 21400328).

[0140] The rheometer consists of two identical (20mm diameter) parallel tanks. The tanks are heated to the test temperature. Only one tank is used for the swelling measurement (sheath number 1).

[0141] The mixture to be tested is placed in the tank, it is then compressed by a piston which forces this mixture to evacuate through the die (extrusion of the mixture) located at the bottom of the tank. The length, diameter and surface condition of the two dies are known. The piston moves at different speed levels predefined by the user. The pressure is measured throughout the acquisition in order to calculate the rheological characteristics of the material.

[0142] The measurement result is the result of a single measurement. The result obtained is a swelling index (unitless number) for each speed step. Swelling index

[0143] The results are expressed on a basis of 100 relative to the control (the value of 100 is given to the control). Preparation of rubber compositions:

[0144] The compositions are manufactured in suitable mixers, using two successive preparation phases well known to those skilled in the art: a first thermo-mechanical working or kneading phase (sometimes referred to as the "non-productive" phase) at high temperature, up to a maximum temperature of between 110°C and 200°C, preferably between 130°C and 180°C, followed by a second mechanical working phase (sometimes referred to as the "productive" phase) at a lower temperature, typically below 110°C, for example between 60°C and 100°C, a finishing phase during which the crosslinking or vulcanization system is conventionally incorporated; such phases have been described, for example, in applications EP-A-0501227, EP-A-0735088, EP-A-0810258, WO 00 / 05300 or WO 00 / 05301.

[0145] The compositions are cooked at 140°C for 50 minutes.

[0146] Tests

[0147] Tests were carried out with different rubber compositions shown in Table 1.

[0148] The formulations of the prepared compositions are described in Table 1 (components and content - unless otherwise indicated, the contents are expressed in pce).

[0149] Table 1: formulations of the compositions

[0150] (1) WTR80-0 marketed by Leghih Technologies

[0151] (2) P550 marketed by the company Scandinavian Enviro Systems (ash (%): 18.5; sulfur (%): 3; zinc (%): 4.5; specific surface STSA: 56 m 2 / g (ASTM D6556-2021); void volume at 50MPa: 44ml / 100g (ASTM D7854-21))

[0152] (3) Ultrasil ® 7000GR” marketed by the company EVONIK

[0153] (4) Combination of two antioxidants TMQ ((N-(1,3-dimethylbutyl)-N-phenyl-para-phenylenediamine (“Santoflex 6-PPD” from Flexsys) and 2,2,4-trimethyl-1,2-dihydroquinolone (“TMQ” from Lanxess)

[0154] (5) Zinc Oxide (industrial grade) marketed by Unicore

[0155] (6) Stearin marketed by the company Unigema under the name "Pristerene 4931"

[0156] (7) N-cyclohexyl-2-Benzothiazyl-sulfenamide marketed by the company Flexsy under the name 'Santocunre CBS'

[0157] (8) Diphenylguanidine “Perkacit DPG” from Flexsys

[0158] The properties of the compositions measured as cooked are presented in Table 2.

[0159] Table 2: Properties of the compositions

[0160] The tests carried out show that a reduction in the rate of reinforcing fillers in a rubber composition leads to compositions exhibiting gains in hysteresis (compositions T and C1). However, this gain in hysteresis is accompanied by a reduction in the tear energy and a degradation in the processability of the compositions (IG 80s-1). In fact, the swelling of the compositions reaches levels making the compositions less efficient for use in commonly used industrial equipment.

[0161] Comparing compositions C1 and C2, it can be observed that an increase in the total charge volume allows for a reduction in swelling. However, this effect is accompanied by a deterioration in rolling resistance performance (increase in G”10% return).

[0162] Surprisingly, it was observed that for the same total charge volume (comparison of C2 and INV compositions), the partial substitution of silica by pyrolysis carbon black makes it possible to achieve a good performance / processability compromise.

Claims

Tl CLAIMS 1. Tire provided with an external sidewall, the external sidewall comprising at least one rubber composition based on: - at least one elastomer; - 16 to 20% by volume, relative to the total volume of the composition, of reinforcing fillers; and - a crosslinking system; reinforcing fillers comprising: - from 6 to 16%, preferably from 6 to 11%, by volume, relative to the total volume of the composition, of reinforcing fillers selected from the group consisting of reinforcing inorganic fillers, carbon blacks having a CTAB specific surface area greater than or equal to 90 m 2 / g and mixtures of reinforcing inorganic fillers and carbon blacks having a CTAB specific surface area greater than or equal to 90 m 2 / g in which the reinforcing inorganic filler is the majority by mass; - pyrolysis carbon blacks in sufficient quantity to achieve a volume of reinforcing fillers in the composition ranging from 16% to 20% relative to the total volume of the composition.

2. Tire according to claim 1, in which the or each elastomer is a diene elastomer chosen from the group consisting of polybutadienes (BR), natural rubber (NR), synthetic polyisoprenes (IR), butadiene copolymers, isoprene copolymers, and mixtures of these elastomers.

3. A tire according to claim 1 or 2, wherein the rubber composition comprises from 25 to 100 pce of natural rubber and from 0 to 75 pce of at least one polybutadiene.

4. A tire according to claim 3, wherein the rubber composition comprises 50 pce of natural rubber and 50 pce of polybutadiene.

5. Tire according to any one of claims 1 to 4 in which the carbon blacks have a CTAB specific surface area greater than or equal to 90 m 2 / g are selected from the reinforcing carbon blacks of the 100 and 200 series.

6. Tire according to any one of claims 1 to 5 in which the reinforcing inorganic fillers are silica.

7. A tire according to any one of the preceding claims, wherein the crosslinking system is a vulcanization system based on molecular sulfur and / or a sulfur donor agent.

8. A tire according to any one of the preceding claims, wherein the vulcanization system comprises between 0.5 and 10 pce of sulfur, preferably between 1 and 5 pce.

9. A tire according to any one of the preceding claims, wherein the pyrolysis carbon black has an ash content ranging from 5 to 30% by weight, preferably from 8 to 25% by weight, relative to the total weight of the pyrolysis carbon black.

10. Tire according to any one of the preceding claims, in which the pyrolysis carbon black has a sulfur content greater than 2% by weight, preferably ranging from 2.5 to 5% by weight, relative to the total weight of the pyrolysis carbon black.

11. A tire according to any one of the preceding claims, wherein the composition further comprises one or more agents selected from the group consisting of plasticizers, non-reinforcing fillers, pigments, protective agents such as anti-ozone waxes, chemical anti-ozonants, antioxidants, anti-fatigue agents and reinforcing resins.

12. A tire according to any one of the preceding claims, wherein the reinforcing fillers are reinforcing inorganic fillers or mixtures of reinforcing inorganic fillers and carbon blacks having a CTAB specific surface area greater than or equal to 90 m 2 / g in which the reinforcing inorganic filler is the majority by mass.

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