Radial-reinforced pneumatic tire

Abstract

The present invention relates to a tire (1) with a radial carcass reinforcement (2). The tire (1) comprises, between the carcass reinforcement elements (2) and the tire cavity (8), a rubber compound comprising a composition based on: - an isoprene elastomer; - 40 to 70 parts per annum of reinforcing fillers, of which at least 10 parts per annum of pyrolysis carbon black, preferably at least 30 parts per annum of pyrolysis carbon black; and - a crosslinking system. Figure 1a

Description

Title of the invention: Pneumatic tire with radial carcass reinforcement FIELD OF THE INVENTION

[0001] The present invention relates to a tire with a radial carcass reinforcement, more particularly a tire intended to equip vehicles carrying heavy loads and traveling at high speed, such as for example trucks, tractors, trailers and road buses. TECHNOLOGICAL BACKGROUND

[0002] Generally speaking, a tire comprises a tread, intended to come into contact with a ground via a rolling surface, the two axial ends of which are connected via two sidewalls with two beads ensuring the mechanical connection between the tire and the rim on which it is intended to be mounted. A radial tire further comprises a reinforcing reinforcement, consisting of a crown reinforcement, radially inside the tread, and a carcass reinforcement, radially inside the crown reinforcement.

[0003] The rubber compound, located between the carcass reinforcement and the tire cavity, more precisely between the carcass reinforcement and the tire sealing layer, must be both a chemical and physical barrier to oxygen in order to limit the diffusion of oxygen inside the tire. The rubber compound must thus be capable of reacting with oxygen (chemical barrier) and be impermeable to oxygen (physical barrier).

[0004] By limiting the diffusion of oxygen in the lower zone and / or in the crown of the tire, this rubber mixture contributes to the endurance of the tire.

[0005] It is known to those skilled in the art that the oxygen reactivity of a rubber mixture can be promoted by increasing the sulfur content of the mixture. However, this increase in oxygen reactivity is accompanied by an increased risk of nodule formation during the shaping of the mixture due to a reduced curing tO of the mixture.

[0006] It is also known to those skilled in the art that the impermeability to air, and therefore to oxygen, of a rubber mixture can be promoted by increasing the content of reinforcing fillers in the mixture, for example carbon black. However, this increase in impermeability is achieved to the detriment of the rolling resistance of the tire, the increase in the content of reinforcing fillers also increasing the hysteresis.

[0007] Thus, a need remains for the provision of a rubber compound, which can be placed between the carcass reinforcement and the cavity of a tire, more precisely precisely between the carcass reinforcement and the sealing layer of the tire, presenting improved impermeability and reactivity to oxygen as well as better rolling resistance while having a preserved level of rigidity and which does not affect the shaping of the mixture. Advantageously, the proposed solution will make it possible to reduce the environmental footprint of tires with radial carcass reinforcement by incorporating a significant proportion of recycled materials. BRIEF DESCRIPTION OF THE INVENTION

[0008] The present invention relates to a tire with a radial carcass reinforcement consisting of at least one layer of reinforcing elements, the tire comprising a crown reinforcement, itself radially capped with a tread, the tread being joined to two beads by means of two sidewalls, characterized in that the tire comprises, between the reinforcing elements of the carcass reinforcement and the cavity of the tire, a rubber mixture, said rubber mixture comprising a composition based on:

[0009] - an isoprene elastomer;

[0010] - 40 to 70 pce of reinforcing fillers, including at least 10 pce of carbon black pyrolysis, preferably at least 30 pce of pyrolysis carbon black; and

[0011] - a crosslinking system.

[0012] Other aspects of the invention are as described below and in the claims. DEFINITIONS

[0013] 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 thus being able to be in a totally or partially crosslinked state or in a non-crosslinked state.

[0014] By the expression "part by weight per hundred parts by weight of elastomer" (or pce), it is meant the part, by mass per hundred parts by mass of elastomer or rubber, the two terms being synonymous.

[0015] In this document, unless expressly indicated otherwise, all percentages (%) indicated are percentages (%) by mass.

[0016] 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 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 the present, when describing an interval of values ​​by the expression "from a to b", we also and preferentially describe the interval represented by the expression "between a and b".

[0017] The expression "radial" refers to a radius of the tire. It is in this sense that 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 axis of rotation of the tire 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 axis of rotation of the tire than point P4. We will say that we are moving "radially inward (or outward)" when we are moving in the direction of smaller (or larger) radii. When we are talking about radial distances, this meaning of the term also applies.

[0018] By "radial cut" or "radial section" is meant here a cut or a section along a plane which contains the axis of rotation of the tire.

[0019] An “axial” direction is a direction parallel to the axis of rotation of the tire. A point P5 is said to be “axially inside” a point P6 (or “axially inside” point P6) if it is closer to the median plane of the tire than point P6. Conversely, a point P7 is said to be “axially outside” a point P8 (or “axially outside” point P8) if it is further from the median plane of the tire than point P8. The “median plane” of the tire is the plane which is perpendicular to the axis of rotation of the tire and which is equidistant from the annular reinforcement structures of each bead.

[0020] A “circumferential” direction is a direction that is perpendicular to both a tire radius and the axial direction.

[0021] 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.

[0022] The cooking time of a rubber mixture designates the time allowing the processability of the mixture before the formation of crosslinking bridges (induction time). DETAILED DESCRIPTION OF THE INVENTION

[0023] Surprisingly, the inventors have discovered that the use of pyrolysis carbon black in a rubber mixture makes it possible to improve the oxygen reactivity properties and the oxygen impermeability of the latter without reducing the level of rigidity while reducing the level of hysteresis and increasing the cooking tO of the mixture.

[0024] Thus, the present invention relates to a tire with a radial carcass reinforcement. consisting of at least one layer of reinforcing elements, the tire comprising a crown reinforcement, itself radially capped with a tread, the tread being joined to two beads by means of two sidewalls, characterized in that the tire comprises, between the reinforcing elements of the carcass reinforcement and the cavity of the tire, a rubber mixture, said rubber mixture comprising, or consisting of, a composition based on:

[0025] - an isoprene elastomer;

[0026] - 40 to 70 pce of reinforcing fillers, including at least 10 pce of carbon black pyrolysis, preferably at least 30 pce of pyrolysis carbon black; and

[0027] - a crosslinking system.

[0028] The composition may further comprise usual additives and implementing agents.

[0029] The various constituents of the composition may be as described below. Elastomer

[0030] The composition useful in the context of the present invention is based on an isoprene elastomer.

[0031] By "isoprenic elastomer" is meant, in a known manner, a homopolymer or a copolymer of isoprene, in other words an elastomer chosen from the group consisting of natural rubber (NR), synthetic polyisoprenes (IR), isoprene copolymers (e.g. copolymer of isobutene and isoprene) and their mixtures.

[0032] Preferably, the composition useful in the context of the present invention is based on an isoprene elastomer chosen from the group consisting of natural rubber, synthetic polyisoprenes and their mixtures. The elastomer is then typically made up of 70 to 100 phr of natural rubber and 0 to 30 phr of synthetic polyisoprenes.

[0033] In certain embodiments, the composition useful in the context of the present invention is based on natural rubber. In other words, the composition does not comprise other elastomers. Reinforcing charge

[0034] The composition useful in the context of the present invention comprises from 40 to 70 phr of reinforcing fillers, including at least 10 phr of pyrolysis carbon black, preferably at least 30 phr of pyrolysis carbon black.

[0035] The term “reinforcing filler” designates any type of filler known for its ability to reinforce a rubber composition which 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.

[0036] In addition to the pyrolysis carbon black, the composition may therefore also comprise an inorganic reinforcing filler (e.g. silica or alumina) or an organic reinforcing filler such as carbon black so as to achieve a total content of reinforcing fillers ranging from 40 to 70 pce.

[0037] In certain embodiments, the composition comprises from 40 to 70 phr of reinforcing fillers, the reinforcing fillers being pyrolysis carbon black. It must then be understood that the composition comprises pyrolysis carbon black as the only reinforcing fillers (the composition therefore does not comprise inorganic reinforcing fillers and other organic reinforcing fillers).

[0038] The reinforcing fillers may be as described below. Pyrolysis carbon black

[0039] The composition useful in the context of the invention comprises at least 10 phr of pyrolysis carbon black, preferably at least 30 phr of pyrolysis carbon black.

[0040] In some embodiments, the composition comprises from 40 to 70 phr of pyrolysis carbon black.

[0041] 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 a 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 the crosslinked or non-crosslinked state.

[0042] Preferably, the material to be pyrolyzed may be recovered from manufactured articles or from 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 comes from manufactured articles chosen from the group consisting of pneumatic tires and non-pneumatic tires.

[0043] Pyrolysis in the context of the present invention means any type of thermal decomposition in the absence of oxygen and the raw material of which 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 carbonaceous raw material used for pyrolysis is a material comprising at least one carbonaceous polymer and one carbon black and not materials derived from pe- from coal or from natural oils.

[0044] The pyrolysis carbon blacks which 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 “fumac” carbon blacks, in particular by a higher ash content.

[0045] Preferably, the pyrolysis carbon black usable in the context of the present invention has an ash content ranging from 5 to 30% by weight, more preferably ranging from 8 to 25% by weight, even more preferably ranging from 10% to 22% by weight, relative to the total weight of the pyrolysis carbon black.

[0046] Preferably, the pyrolysis carbon black usable in the context of the present invention 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.

[0047] 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 ranging from 2.5 to 8% by weight, relative to the total weight of the pyrolysis carbon black.

[0048] 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 m2 / g, more preferably from 30 to 90 m2 / g.

[0049] Preferably, the pyrolysis carbon black usable in the context of the present invention has a void volume measured according to standard ASTM D7854 (2018) and at a pressure of 50 MPa within a range from 30 to 60 ml / 100g, more preferably from 35 to 55 ml / 100g.

[0050] 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, 5g of pyrolysis carbon black sample is introduced and weighed precisely to the nearest 0.1 mg; this mass is noted PL 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: .

[0051] [Math.l] P2 - PO % cexidra ~ ——— X 100 PI - PO

[0052] The zinc content in the pyrolysis carbon black is determined after calcination of the sample, then recovery of the ash in an acid medium and determination by ICP-AES (inductively coupled plasma atomic emission spectroscopy). The ash is obtained by carrying out the above protocol. Approximately 100 mg of ash (test sample) is taken and placed in a PFA (perfluoroalkoxy) tube for a HotBlock 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 hours. 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 mark.The solution obtained is diluted by 100, by taking 1 mL from 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). Prior to the analysis of 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.

[0053] These volumetric flasks first 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 XZn = 202.613 nm. For each standard concentration (c), the intensity of the zinc signal 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:

[0054] [Math.2] the black [c]œn*ss * 100 * % ashes

[0055] 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 carrying out the measurement of the sulfur content on the sample, cleaning of the nacelles and calibration of the furnace are carried out. The nacelles for LECO furnace are previously cleaned: this involves analyzing the empty nacelle, 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 in a basket.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 SO2(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 SO2(g), are carried by an oxygen flow through the infrared detection cells. The instrument software plots 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 are weighed exactly and introduced into a LECO furnace 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.

[0056] 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”. Carbon black

[0057] The composition useful in the context of the invention may comprise carbon black.

[0058] Suitable carbon blacks are all carbon blacks, in particular the blacks conventionally used in tires or their treads, in particular industrial carbon blacks, more specifically so-called “furnace” carbon blacks.

[0059] Among the carbon blacks, mention will be made more particularly of the reinforcing carbon blacks of the 100, 200, 300 series, or the blacks of the 500, 600 or 700 series (ASTM grades D-1765-2017), such as blacks NI 15, N134, N234, N326, N330, N339, N347, N375, N550, N683, N772. Preferably, the carbon blacks are selected from the group consisting of series blacks 300, 500, 600 and 700.

[0060] 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. 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 WO97 / 36724-A2 or WO99 / 16600-A1). Reinforcing inorganic filler

[0061] The composition useful in the context of the invention may comprise a reinforcing inorganic filler.

[0062] 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. In a known manner, certain reinforcing inorganic fillers can be characterized in particular by the presence of hydroxyl groups (-OH) on their surface.

[0063] Suitable reinforcing inorganic fillers include, in particular, mineral fillers of the siliceous type, preferably silica (SiO2) or of the aluminous type, in particular alumina (A12O3). 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 CT AB specific surface area both less than 450 m2 / g, preferably within a range from 30 to 400 m2 / g, in particular from 60 to 300 m2 / g.

[0064] Any type of precipitated silica may be used, in particular highly dispersible precipitated silicas (known as "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 that may be mentioned are the silicas described in applications WO03 / 016215-A1 and WO03 / 016387-A1. Among the commercial HDS silicas, we can notably use 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 the PPG company.

[0065] 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 CT AB specific surface area of ​​silica is determined according to the French standard NF T 45-007 of November 1987 (method B).

[0066] As other examples of inorganic fillers that can be used in the compositions, mention may also be made of mineral fillers of the aluminous type, in particular alumina (A12O3), 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, US6610261-B1 and US6747087-B2. Examples include the aluminas “Baikalox A125” or “CR125” (Baïkowski company), “APA-100RDX” (Condéa), “Aluminoxid C” (Evonik) or “AKP-G015” (Sumitomo Chemicals).

[0067] The physical state in which the reinforcing inorganic filler is present 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.

[0068] 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.

[0069] A person skilled in the art will be able to adapt the total rate of reinforcing filler 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.

[0070] To couple the reinforcing inorganic filler to the diene elastomer, it is possible to use in a well-known manner a coupling agent (or bonding agent) at least bi functional group 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.

[0071] 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 TES PD 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.

[0072] The person skilled in the art can find examples of coupling agents 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.

[0073] 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 content is less than 20 phr, preferably within a range from 6 to 17 phr, preferably from 8 to 15 phr. This content can easily be adjusted by a person skilled in the art according to the content of inorganic filler used in the composition.

[0074] 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 ability to be processed 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 stearic acid. Other organic loads

[0075] The composition useful in the context of the invention may comprise a reinforcing organic filler of functionalized polyvinyl type as described in applications WO 2006 / 069792-Al, WO 2006 / 069793-Al, WO 2008 / 003434-Al and WO 2008 / 003435-Al. Crosslinking system

[0076] The composition useful in the context of the invention comprises a crosslinking system.

[0077] 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.

[0078] 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.

[0079] Sulphur is used at a preferential rate of between 0.5 and 12 pce, in particular between 1 and 10 pce, preferably between 2 and 9 pce.

[0080] The vulcanization accelerator is used at a preferential rate of between 0.1 and 10 pce, more preferably between 0.3 and 1.0 pce.

[0081] The vulcanization activator is used at a preferential rate of between 1 and 10 pce, more preferably between 3.3 and 10 pce.

[0082] 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 the following compounds: 2-mercaptobenzothiazyl disulfide (abbreviated "MBTS"), N-cy- clohexyl-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 implementing agents

[0083] 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, such as, for example, plasticizers (such as plasticizing oils and / or plasticizing resins), non-reinforcing fillers, pigments, agents promoting green tack (i.e., tackifying agent, for example rosin), pro-oxidizing metal salts, protective agents such as anti-ozone waxes, chemical anti-ozonants, antioxidants, anti-fatigue agents, reinforcing resins (as described, for example, in application WO 02 / 10269).

[0084] In certain embodiments, the composition useful in the context of the invention comprises more than 0 to 5 phr of a green stickiness promoting agent, for example from 1 to 5 phr of a green stickiness promoting agent.

[0085] In certain embodiments, the composition useful in the context of the invention comprises from 0.3% to 4% by mass relative to the total mass of the composition of one or more antioxidant agent(s), preferably from 0.5% to less than 0.7% by mass.

[0086] The antioxidant agent may be of the amine, phenol, imidazole, para-phenylenediamine(s) and / or dihydrotrimethylquinoline(s) type, polymerized quinine, wax or any other antioxidant usually used in elastomer formulations.

[0087] Specific examples include: N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6-PPD, marketed for example under the trademarks ANTIGENE® 6C by Sumitomo Chemical Co., Ltd. NOCLAC® 6C by Ouchi Shinko Chemical Industrial Co., Ltd.), the product "Ozonon" 6C marketed by Seiko Chemical Co., Ltd., polymerized 1,2-dihydro-2,2,4-trimethyl quinoline (TMQ, marketed for example under the trademark Agerite Resin D, by RT Vanderbilt), butylhydroxytoluene (BHT), and butylhydroxyanisole (BHA).

[0088] The antioxidant agent is advantageously an N-alkyl-N'-phenyl-paraphenyldiamine corresponding to the formula (I):

[0089] [Chem.l] (I)

[0090] in which R1 represents a linear or branched alkyl group having from 1 to 12 carbon atoms or a cycloalkyl group having from 5 to 8 carbon atoms.

[0091] Preferably, R1 represents an alkyl having from 2 to 8 carbon atoms, preferably chosen from the group consisting of ethyl, propyl (i.e., n-propyl, iso-propyl), butyl (i.e., n-butyl, sec-butyl and tert-butyl), pentyl, hexyl, heptyl and octyl, or a cycloalkyl group having from 5 to 8 carbon atoms (cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl), more preferably a cyclohexyl group.

[0092] More preferably, compounds are used whose R1 groups are branched, of formulas (I -bis) below:

[0093] [Chem.2] 0 hkO

[0094] in which R4, R5, identical or different from each other, each represent an alkyl group whose number of carbon atoms conforms to the preferred definitions given above for R1.

[0095] As more preferred examples of branched radicals R1, mention will be made in particular of isopropyl, 1,3-dimethylbutyl and 1,4-dimethylpentyl.

[0096] The compounds of formula (Lbis) above are well known to those skilled in the art. They have been used for a very long time as anti-aging protection agents in rubber compositions for tires, particularly in the belts of such tires, and belong to the family of paraphenylenediamine ("PPD") derivatives such as, for example:

[0097] N-isopropyl-N'-phenyl-paraphenylenediamine ("I-PPD")

[0098] [Chem.3]

[0099] or Nl,3-dimethylbutyl-N'-phenyl-paraphenylenediamine ("6-PPD")

[0100] [Chem.4]

[0101] (see for example applications WO 2004 / 033548, WO 2005 / 063510, WO 2005 / 133666).

[0102] In certain embodiments, the composition useful in the context of the present invention comprises one or more pro-oxidizing metal salts whose content determined on the basis of the metal element varies from 0.05 to 0.15g of metal per 100g of the composition or from 0.07 to 0.15g of metal per 100g of the composition.

[0103] A pro-oxidant metal salt accelerates oxygen fixation by catalyzing oxidation.

[0104] Such salts are well known to those skilled in the art. Examples of pro-oxidizing metal salts include, but are not limited to, cobalt salts, in particular cobalt salts selected from the group consisting of abietates, acetyla-ketonates, tallates, naphthenates, resinates and mixtures thereof, manganese salts or iron salts (e.g. iron III salts as described in WO 99 / 24502 ​​or WO 00 / 68309).

[0105] In certain embodiments, the composition useful in the context of the invention is a composition based on:

[0106] - an isoprene elastomer;

[0107] - 40 to 70 pce of reinforcing fillers, including at least 10 pce of carbon black pyrolysis, preferably at least 30 pce of pyrolysis carbon black;

[0108] - a crosslinking system, preferably the crosslinking system (eg, a vulcanization system) including:

[0109] - between 0.5 and 12 pce, in particular between 1 and 10 pce, preferably between 2 and 9 pce, of sulfur;

[0110] - between 0.1 and 10 pce, preferably between 0.3 and 1.0 pce of one or more access vulcanization lerators;

[0111] - between 1 and 10 pce, preferably between 3.3 and 10 pce, of one or more ac vulcanization activators;

[0112] - 0.3% to 4% by mass, preferably from 0.5% to less than 0.7% by mass, relative to to the total mass of the composition of one or more antioxidant agent(s); and

[0113] - one or more pro-oxidizing metal salts whose content is determined on the basis of the metal element varies from 0.05 to 0.15 g of metal per 100 g of the composition, preferably 0.07 to 0.15 g of metal per 100 g of the composition. Special embodiments

[0114] In certain embodiments, the composition useful in the context of the invention is a composition based on:

[0115] - an isoprene elastomer;

[0116] - 40 to 70 pce of reinforcing fillers, including at least 10 pce of carbon black pyrolysis, preferably at least 30 pce of pyrolysis carbon black;

[0117] - a crosslinking system, preferably the crosslinking system (eg a system vulcanization) including:

[0118] - between 0.5 and 12 pce, in particular between 1 and 10 pce, preferably between 2 and 9 pce, of sulfur;

[0119] - between 0.1 and 10 pce, preferably between 0.3 and 1.0 pce of one or more access vulcanization lerators;

[0120] - between 1 and 10 pce, preferably between 3.3 and 10 pce, of one or more ac vulcanization agents; and

[0121] - 0.7% to 4%, preferably 0.8% to 4% by mass relative to the total mass of the composition of one or more antioxidant agents.

[0122] The composition may further comprise one or more pro-oxidizing metal salts whose content determined on the basis of the metal element varies from 0.05 to 0.15g of metal per 100g of the composition, preferably from 0.07 to 0.15g of metal per 100g of the composition.

[0123] The inventors have discovered that the use of pyrolysis carbon black in a rubber mixture advantageously makes it possible to increase the contents of antioxidant agents in the latter without degrading the capacity of the mixture to react with oxygen and without reducing the cooking tO of the mixture.

[0124] In certain embodiments, the composition useful in the context of the invention is a composition based on:

[0125] - an isoprene elastomer;

[0126] - 40 to 70 pce of reinforcing fillers, including at least 10 pce of carbon black pyrolysis, preferably at least 30 pce of pyrolysis carbon black;

[0127] - a crosslinking system, preferably the crosslinking system (eg, a vulcanization system) including:

[0128] - between 0.5 and 12 pce, in particular between 1 and 10 pce, preferably between 2 and 9 pce, of sulfur;

[0129] - between 0.1 and 10 pce, preferably between 0.3 and 1.0 pce of one or more access vulcanization lerators;

[0130] - between 1 and 10 pce, preferably between 3.3 and 10 pce, of one or more ac vulcanization agents; and

[0131] - less than 0.07g of metal from a pro-oxidizing metal salt per 100g of composition, preferably less than 0.05g, or even less than 0.02g or less than 0.01g of metal from a pro-oxidizing metal salt per 100g of composition, even more preferably 0g of metal from a pro-oxidizing metal salt.

[0132] The composition may further comprise from 0.3 to 4% by mass relative to the total mass of the composition of one or more antioxidant agent(s), preferably from 0.5 to less than 0.7% by mass.

[0133] The inventors have discovered that the use of pyrolysis carbon black in a rubber mixture advantageously makes it possible to reduce the metal salt content without degrading the oxygen reactivity properties and this while increasing the curing tO of the mixture. The composition thus advantageously makes it possible to avoid the use of metal salts in rubber mixtures without degrading other performances such as endurance and shaping. The proposed solution makes it possible to improve the overall impact on the environment and to reduce the cost of the mixtures. Production of compositions

[0134] The 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: - 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.

[0135] 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 the whole is then mixed for a few minutes, for example between 1 and 30 min.

[0136] 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.

[0137] The composition may be either in the raw state (before crosslinking or vulcanization), or in the cured state (after crosslinking or vulcanization), and may be a semi-finished product which may be used in a tire.

[0138] 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. TIRES

[0139] The compositions described above are particularly useful for forming the inner wall of a tire with a radial carcass reinforcement, more particularly for being arranged between the reinforcing elements of the carcass reinforcement and the cavity of the tire, even more precisely between the reinforcing elements of the carcass reinforcement and the sealing layer of the tire.

[0140] In certain embodiments, the tire of the present invention as described above is characterized in that the rubber mixture between the tire cavity and the reinforcing elements of the carcass reinforcement consists of at least two layers of rubber mixture, the layer of rubber mixture, radially adjacent to the radially innermost layer of rubber mixture, comprising, or consisting of, a composition as described above. In other words, the layer of rubber mixture comprising, or consisting of, a composition as described above is located between the carcass reinforcement and the sealing layer of the tire (radially innermost layer of rubber mixture).The tires targeted by the invention are therefore tires comprising, in addition to the carcass reinforcement and the sealing layer, an additional layer of rubber mixture as described above. Thus, this layer is not in direct contact with the air.

[0141] The tire of the present invention may be as described with reference to the following figures.

[0142] - [Fig. la], a meridian view of a diagram of a tire according to a method of rea lization of the invention,

[0143] - [Fig.lb], an enlarged partial view of part of the diagram of [Fig.la]. The figures are not shown to scale to simplify understanding. In [Fig.1a] and [Fig.1b], the tire 1, of size 315 / 70 R 22.5, comprises a radial carcass reinforcement 2 anchored in two beads 3, around bead wires 4. The carcass reinforcement 2 is formed of a single layer of metal cords 11 and two layers of calendering 13. The carcass reinforcement 2 is bound by a crown reinforcement 5, itself capped with a tread 6.

[0144] [Fig.lb] illustrates an enlargement of zone 7 of [Fig.la] and indicates in particular the thickness E of rubber mixture between the inner surface 10 of the cavity 8 of the tire and the point 12 of a reinforcing element 11 closest to said surface 10. This thickness E is equal to the length of the orthogonal projection of the point 12 of a reinforcing element 11 closest to said surface 10 on the surface 10. This thickness E is the sum of the thicknesses of the different rubber mixtures placed between said reinforcing element 11 of the carcass reinforcement 2; this is on the one hand the thickness of the radially inner calendering layer 13 of the carcass reinforcement and on the other hand, the thicknesses e1, e2 of the different layers 14, 15 of rubber mixture forming the internal wall of the tire 1.These thicknesses el, e2 are also equal to the length of the orthogonal projection of a point of one surface onto the other surface of the layer concerned respectively 14 or 15. .

[0145] The compositions described above are particularly useful for forming the rubber mix layer 14 (rubber mix layer radially adjacent to the radially innermost rubber mix layer 15).

[0146] The following examples are given for illustrative purposes. They should in no way be considered as limiting the present invention. EXAMPLES Example 1 Measurement method Rheometry:

[0147] The measurements are carried out at 140°C with an oscillating chamber rheometer, according to DIN 53529 - part 3 (June 1983). The evolution of the rheometric torque as a function of time describes the evolution of the stiffening of the composition as a result of the vulcanization reaction. The measurements are processed according to DIN 53529 - part 2 (March 1983).

[0148] tO is the induction time, i.e. the time required for the start of the reaction of vulcanization.

[0149] ta is the time required to achieve a conversion of a%, i.e. a% of the difference between the minimum and maximum torques of the crosslinked composition.

[0150] t99 is therefore the time required to reach 99% of the conversion. Dynamic properties:

[0151] The dynamic properties and in particular G* 10% return to 60°C and G' ' 10% return to 60°C, respectively representative of 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 4 mm thick and 400 mm2 in cross-section), subjected to sinusoidal stress in alternating simple shear, at the frequency of 1100 Hz, at a temperature of 60°C, is recorded.

[0152] For the measurements of dynamic complex shear modulus (G*) and loss factor (G”), a strain amplitude sweep is carried out 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%.

[0153] The results are expressed on a basis of 100 relative to the control (the value of 100 is given to the control). Oxygen reactivity measurements:

[0154] 7 samples of mixtures 6 / 10ths of a mm thick are cooked at 140°C for a duration corresponding to t99.

[0155] The rate of oxygen initially contained in this sample is measured.

[0156] The remaining 6 samples are placed in a study under air at 85°C for the following aging times respectively: 3, 5, 7, 10, 12 and 14 days.

[0157] The oxygen level contained in each of the 6 aged samples is then measured.

[0158] For each of the 7 samples, the fixed oxygen level is calculated: oxygen level measured in the aged sample - oxygen level measured in the initial sample.

[0159] The reactivity with oxygen of the mixture then corresponds to the slope of the straight line linking the fixed oxygen level (in mass %) to the number of days of aging at 85°C in air (in days).

[0160] The results are expressed on a basis of 100 relative to the control (the value of 100 is given to the control). Oxygen level measurements:

[0161] The cooked mixture is introduced into a pyrolysis chamber at a temperature of around 1000°C, swept by a constant current of helium.

[0162] The pyrolysate passes through a carbon reducer. The oxygen is converted into carbon monoxide. The gases pass through sodium hydroxide and a desiccant to remove acid vapors. The carbon monoxide is separated from the other pyrolysis gases by a chromatographic column and detected by a catharometer.

[0163] The oxygen content in the cooked mixture is calculated via a calibration curve made with cholesterol. It is expressed as a mass % of the mixture. Oxygen permeability measurements:

[0164] Oxygen permeability values ​​are measured using a MOCON OXTRAN permeability "tester" at 60°C. Baked samples in the form of discs of a determined thickness (approximately 0.8 to 1 mm) are mounted on the apparatus and sealed with vacuum grease. One face of the disc is maintained under 10 psi of nitrogen while the other face is maintained under lOpsi of oxygen (lpsi = 6894.76 Pa). The increase in oxygen concentration is monitored using a "Coulox" oxygen detector on the face maintained under nitrogen. The oxygen concentration is noted on the face maintained under nitrogen to achieve a constant value, used to determine the oxygen permeability.

[0165] An arbitrary value of 100 is given for the oxygen permeability of the control, a result less than 100 indicating a decrease in oxygen permeability and therefore better impermeability. Preparation of the compositions

[0166] 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 a "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 a "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.

[0167] Cooking is carried out at 140°C for a duration corresponding to t99.

[0168] The mixtures prepared are as described in Table 1 (components and content - unless otherwise indicated, the contents are expressed in pce). ML1 ML2 ML3 ML4 Natural rubber 100 100 100 100 Carbon black (grade 300) 48 Carbon black (grade 500) 37 Pyrolysis carbon black (“P550” from Scandinavian Enviro Systems) 62.5 47.3 Pro-oxidant metal salt Cobalt dihydroxide expressed in grams of cobalt per 100g of mixture (equivalent pce) 0.14 (0.35) 0.13 (0.35) Cobalt naphthenate expressed in grams of cobalt per 100g of mixture (equivalent pce) 0.08 (1.5) 0.075 (1.5) Antioxidant 6PPD expressed in grams per 100g of mixture (equivalent pce) 0.62 (1) 0.57 (1) 0.66 (1) 0.61 (1) Tackifying agent Rosin 1 1 Resin “Impera R1507” Eastman 1 1 Vulcanization system Sulfur 5.5 5.5 5.8 5.8 TBBS 0.6 0.6 0.6 0.6 Stearic acid 0.9 0.9 0.5 0.5 ZnO 5 5 5 5

[0170] Table 1: prepared mixtures

[0171] Mixture ML1 is a control mixture.

[0172] Mixture ML2 is a mixture with iso-rigidity with mixture ML1.

[0173] Mixture ML4 is a mixture with iso-rigidity with mixture ML3. Results :

[0174] The properties of the mixtures are presented in Table 2. ML1 ML2 ML3 ML4 G*10%return at 60°C (MPa) (Base 100 vs. ML1) 100 99 / / G*10%return at 60°C (MPa) (Base 100 vs. ML3) / / 100 95 G” 10%return at 60°C (MPa) (Base 100 vs. ML1) 100 76 / / G” 10%return at 60°C (MPa) (Base 100 vs. ML3) / / 100 105 Reactivity with Oxygen at 85°C (Base 100 vs. ML1) 100 185 / / Reactivity with Oxygen at 85°C (Base 100 vs. ML3) / / 100 235 Oxygen Permeability at 60°C (Base 100 vs. ML1) 100 89 / / Oxygen permeability at 60°C (Base 100 vs. ML3) / / 100 92 tO (min) 5.91 6.98 7.19 8.15

[0176] Table 2: properties of mixtures

[0177] Surprisingly, the inventors have discovered that the use of pyrolysis carbon black in a rubber mixture makes it possible to improve the oxygen reactivity properties and the oxygen impermeability of the latter without reducing the level of rigidity and by increasing the cooking tO of the mixture. Example 2 Measurement method

[0178] Oxygen reactivity measurements and oxygen level measurements

[0179] The measurements are carried out as described in Example 1. Rheometry:

[0180] The measurements are carried out as described in Example 1. Tensile Tests:

[0181] The tests were carried out in accordance with the French standard NF T 46-002 of September 1988. All tensile measurements were carried out under the conditions of temperature (100+ / -2°C) and humidity (50+ / -5% relative humidity) according to the French standard NF T 40-101 (December 1979).

[0182] The elongations at break (AR in %) were measured at 100°C+ / -2°C, according to standard NFT 46-002, on samples cooked for 50 min at 140°C.

[0183] The above test is carried out on the one hand in the initial state and on the other hand after accelerated thermo-oxidative aging of 14 days, the sample of the tested composition then being placed in a ventilated oven maintained at a temperature of 77°C and under an ambient humidity of 40%. Preparation of the compositions

[0184] 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 a "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 a "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.

[0185] Cooking is carried out at 140°C for 50 min for mixtures 1 to 5.

[0186] The mixtures prepared are as described in Table 3 (components and content - unless otherwise indicated, the contents are expressed in pce). ML1 ML2 ML3 ML4 ML5 Elastomer NR 100 100 100 100 100 Carbon black (grade 500) 37 Pyrolysis carbon black (“P550” from Scandinavian Enviro Systems) 47.3 47.3 47.3 47.3 Cobalt naphthenate expressed in grams of cobalt per 100g of mixture (equivalent pce) 0.08 (1.5) 0.075 (1.5) 0.074 (1.5) 0.073 (1.5) 0.073 (1.5) Resin “Impera R1507” Eastman 1 1 1 1 1 Vulcanization system Sulfur 5.8 5.8 5.8 5.8 5.8 TBBS 0.6 0.6 0.6 0.6 0.6 Stearic acid 0.5 0.5 0.5 0.5 0.5 ZnO 5 5 5 5 5

[0188] Table 3: prepared mixtures

[0189] To the components listed above are added one or more antioxidant agents in the following proportions (Table 4): ML1 ML2 ML3 ML4 ML5 6PPD expressed in number of grams per 100g of mixture (equivalent pce) 0.66 (1) 0.61 (1) 0.83 (1.35) 0.61 (1) 0.61 (1) TMQ expressed in number of grams per 100g of mixture (equivalent pce) 0.46 (0.75) 1.2 (2)

[0191] Table 4: nature and content of antioxidant agent in the mixtures

[0192] Mixture ML1 is a control mixture.

[0193] Mixtures ML3, ML4, ML5 are mixtures according to the invention. Results :

[0194] The properties of the mixtures are presented in Table 5. ML1 ML2 ML3 ML4 ML5 Reactivity with Oxygen at 85°C (Base 100 vs. ML1) 100 141 103 103 102 tO (min) at 140°C 7.26 9.17 8.97 9.11 9.15 Initial elongation at break 100°C 403% 565% 544% 598% 574% Elongation at break 100°C after 14-day oven drying at 77°C in air 143% 116% 126% 139% 187%

[0196] Table 5: properties of mixtures

[0197] It can be observed that the mixtures ML3, ML4 and ML5 comprising a total content of antioxidant agents higher than the contents commonly used (ML1 and ML2) exhibit better resistance to thermo-oxidative degradation than the mixture ML2 without reducing their capacity to react with oxygen and without reducing the cooking tO of the mixture. Example 3 Measurement method

[0198] Oxygen reactivity measurements and oxygen level measurements

[0199] The measurements are carried out as described in Example 1. Rheometry:

[0200] The measurements are carried out as described in Example 1. Preparation of the compositions

[0201] The compositions are manufactured in suitable mixers, using two successive preparation phases well known to those skilled in the art: a first working phase or thermo-mechanical mixing (sometimes referred to as a "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 phase of mechanical working (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.

[0202] Cooking is carried out at 140°C for 50 min. Examples

[0203] The mixtures prepared are as described in Table 6 (components and content - unless otherwise indicated, the contents are expressed in pce).

[0204] [Tableauxô] ML1 ML2 ML3 ML4 ML5 ML6 ML7 ML8 ML9 NR 100 100 100 100 100 100 100 100 100 Carbon black (grade 500) 37 37 37 37 37 Pyrolysis carbon black (“P550” from Scandinavian Enviro Systems) 47.3 47.3 47.3 47.3 Cobalt naphthenate expressed as number of grams of cobalt per 100g of mixture (equivalent pce) 0.08 (1.5) 0.075 (1.5) 0 0.012 (0.25) 0.050 (1) 0.08 (1.5) 0 0.013 (0.24) 0.053 (1) 6PPD expressed in number of grams per 100g of mixture (equivalent pce) 0.66 (1) 0.61 (1) 0.62 (1) 0.62 (1) 0.62 (1) 0.66 (1) 0.67 (1) 0.67 (1) 0.66 (1) Resin “Impera R1507” Eastman 1 1 1 1 1 Crosslinking system Sulfur 5.8 5.8 5.8 5.8 5.8 5.8 5.8 5.8 5.8 TBBS 0.6 0.6 0.6 0.6 0.6 0.6 0.6 0.6 0.6 Stearic acid 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 ZnO 5 5 5 5 5 5 5 5 5

[0205] Table 6: prepared mixtures

[0206] Mixtures ML1 and ML6 are control mixtures.

[0207] Mixtures ML3, ML4 and ML5 are mixtures according to the invention.

[0208] Mixtures ML7, ML8 and ML9 are counterexamples without carbon black of pyrolysis. They illustrate the effects of different pro-oxidant metal salt contents (comparison with ML6). Results :

[0209] The properties of the mixtures are presented in Table 7.

[0210] [Tables?] ML1 ML2 ML3 ML4 ML5 ML6 ML7 ML8 ML9 Reactivity with Oxygen at 85°C (Base 100 ML1) 100 141 97 109 117 100 / / / Reactivity with Oxygen at 85°C (Base 100 ML6) / / / / / 100 59 69 81 tO (min) 7.26 9.17 7.36 8.19 9.01 6.58 6.11 6.30 5.63

[0211] Table 7: properties of mixtures

[0212] It can be observed that the use of pyrolysis carbon black in a rubber mixture makes it possible to reduce the metal salt content without degrading the reactivity properties with oxygen and this while increasing the cooking tO of the mixture.

Claims

Claims

1. A tire with a radial carcass reinforcement consisting of at least one layer of reinforcing elements, the tire comprising a crown reinforcement, itself radially capped with a tread, the tread being joined to two beads by means of two sidewalls, characterized in that the tire comprises, between the reinforcing elements of the carcass reinforcement and the cavity of the tire, a rubber mixture, said rubber mixture comprising a composition based on: - an isoprene elastomer; - 40 to 70 phr of reinforcing fillers, including at least 10 phr of pyrolysis carbon black, preferably at least 30 phr of pyrolysis carbon black; and - a crosslinking system.

2. Tire according to the preceding claim in which the isoprene elastomer is chosen from the group consisting of natural rubber (NR), synthetic polyisoprenes (IR), isoprene copolymers (e.g. copolymer of isobutene and isoprene) and their mixtures.

3. A tire according to claim 1 or 2 wherein the elastomer consists of 70 to 100 pce of natural rubber and 0 to 30 pce of synthetic polyisoprenes.

4. A tire according to any one of the preceding claims, in which the pyrolysis carbon black has an ash content ranging from 5 to 30% by weight, preferably ranging from 8 to 25% by weight, more preferably ranging from 10% to 22% by weight, relative to the total weight of the pyrolysis carbon black.

5. A tire according to any one of the preceding claims wherein 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.

6. A tire according to any one of the preceding claims wherein the pyrolysis carbon black has a zinc content greater than or equal to 2% by weight, preferably ranging from 2.5 to 8% by weight, relative to the total weight of the pyrolysis carbon black.

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

8. A tire according to claim 7 wherein the vulcanization system comprises between 0.5 and 12 pce of sulfur, preferably between 2 and 9 pce.

9. A tire according to claim 7 or 8 wherein the vulcanization system comprises between 0.1 and 10 pce, preferably between 0.3 and 1.0 pce of one or more vulcanization accelerators.

10. A tire according to claim 7, 8 or 9 wherein the vulcanization system comprises between 1 and 10 pce, preferably between 3.3 and 10 pce of one or more vulcanization activators.

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, green tack promoting agents, pro-oxidizing metal salts, 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, in which the composition further comprises from 0.3 to 4% by mass relative to the total mass of the composition of one or more antioxidant agent(s).

13. A tire according to any one of the preceding claims wherein the composition further comprises one or more pro-oxidizing metal salts whose content determined on the basis of the metal varies from 0.05 to 0.15 g of metal per 100 g of the composition.

14. A tire according to any preceding claim wherein the rubber mixture between the reinforcing elements of the carcass reinforcement and the tire cavity consists of at least two layers of rubber mixture, the layer of rubber mixture radially adjacent to the radially innermost layer of rubber mixture comprising a composition as described in any one of claims 1 to 13.

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