PNEUMATIC COMPRISING AT LEAST ONE WORKING PLATE

Abstract

The invention relates to a tire comprising at least one working layer including metallic reinforcement elements embedded in a rubber composition based on at least one diene elastomer, 10 to 70 parts by weight per hundred parts of elastomers, abbreviated pc, of reinforcing filler, said reinforcing filler comprising 2 to 60 pc of carbon black and 8 to 60 pc of inorganic reinforcing filler, at least 4 pc of sulfur, a metallic oxide, and 0.1 to 4 pc of a metallic stearate, said composition comprising at most 0.4 pc of stearic acid.

Description

Title of the invention: PNEUMATIC COMPRISING AT LEAST ONE WORKING PLATE Technical field of the invention

[0001] The present invention relates to the field of vehicle tires, and in particular to the field of tires comprising at least one layer reinforced by metallic reinforcing elements. Previous art

[0002] Reinforcing plies for tires or rubber-reinforced articles typically comprise a rubber compound, known as the calendered compound, and metal reinforcing cords. The calendered compound must meet numerous requirements, such as good adhesion to the metal reinforcing cords, hysteresis properties that result in a low contribution to rolling resistance, and good resistance to cracking throughout the tire's service life. These compounds must also be able to be properly calendered around the reinforcing elements and exhibit curing characteristics compatible with the surrounding compounds and their position within the tire.

[0003] Adhesion between the wire ropes and the surrounding rubber is one of the key properties for the effectiveness of reinforcement plies in pneumatic tires or rubber-reinforced articles. Calendering compositions, which include a diene elastomer, particularly natural rubber, and a reinforcing filler, also generally include a specific vulcanization system and, as an adhesion promoter, cobalt salts. This specific vulcanization system usually includes a high sulfur content, a high zinc oxide to stearic acid mass ratio, a so-called slow vulcanization accelerator, and a vulcanization retarder. In these systems, adhesion between the calendering composition and the wire rope is created via the sulfidation of the brass-coated surface of the rope, with the cobalt salts acting to ensure the durability of the adhesion.

[0004] Although these systems are mastered, there is still a need to improve one or more of the performances of the rubber compositions without disturbing the other properties, whether in the crosslinked state or in the raw state.

[0005] Continuing its research, the applicant discovered that a rubber composition based on at least one diene elastomer, of 10 to 70 parts by weight per hundred parts of elastomers, abbreviated pce, of reinforcing filler, said reinforcing filler comprising 2 to 60 parts carbon black and 8 to 60 parts reinforcing inorganic filler, at least 4 parts sulfur, a metal oxide, and 0.1 to 4 parts metal stearate, said composition comprising at most 0.4 parts stearic acid, makes it possible to obtain a good compromise of properties when this composition is used in the working plies of vehicle tires. Detailed description of the invention

[0006] The invention relates to a vehicle tire comprising at least one working layer comprising metallic reinforcing elements embedded in a rubber composition based on at least one diene elastomer, 10 to 70 parts by weight per hundred parts of elastomers, abbreviated pc, of reinforcing filler, said reinforcing filler comprising 2 to 60 pc of carbon black and 8 to 60 pc of inorganic reinforcing filler, at least 4 pc of sulfur, a metallic oxide, and 0.1 to 4 pc of a metallic stearate, said composition comprising at most 0.4 pc of stearic acid. Definitions

[0007] The compounds mentioned in the description may be of fossil origin or bio-based. In the latter case, they may be partially or totally derived from biomass or obtained from renewable raw materials derived from biomass. Obviously, the compounds mentioned may also come from the recycling of materials already in use, that is to say, they may be partially or totally derived from a recycling process, or even obtained from raw materials themselves derived from a recycling process. This includes, in particular, polymers, plasticizers, fillers, etc.

[0008] 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 manufacturing the composition; the composition can thus be in a totally or partially crosslinked state or in a non-crosslinked state.

[0009] The expression "part by weight per hundred parts by weight of elastomer" (or pce) is to be understood in the present description as the part, by mass per hundred parts by mass of elastomer.

[0010] In this document, unless expressly stated otherwise, all percentages (%) indicated are percentages (%) by mass.

[0011] On the other hand, any interval of values ​​designated by the expression "between a and b" represents the domain of values ​​ranging from greater than a to less than b (i.e., excluding bounds 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 (that is, including the strict bounds a and b).

[0012] In this description, "pneumatic" (in English "tire" or "tire") means a vehicle tire, whether the tire is pneumatic, i.e. supporting the vehicle's load by means of a pressurized gas, or a non-pneumatic tire, i.e. supporting the vehicle's load by means other than a pressurized gas, for example by means of guy wires. Dienic elastomer

[0013] The tire according to the invention comprises at least one working layer comprising metallic reinforcement elements embedded in a rubber composition based on at least one diene elastomer.

[0014] By "diene" elastomer (or indistinctly rubber), whether natural or synthetic, is to be understood in a known way as an elastomer consisting at least in part (i.e., a homopolymer or a copolymer) of diene monomer units (monomers bearing two carbon-carbon double bonds, conjugated or not).

[0015] These diene elastomers can be classified into two categories: "essentially unsaturated" or "essentially saturated". Generally, "essentially unsaturated" means a diene elastomer derived at least in part from conjugated diene monomers, having a proportion of diene motifs or units (conjugated dienes) greater than 15% (mole percent); thus, diene elastomers such as butyl rubbers or EPDM-type diene-alpha-olefin copolymers do not fall under the preceding definition and can be described in particular as "essentially saturated" diene elastomers (low or very low proportion of diene motifs, always less than 15% by mole).

[0016] In the present application, diene elastomers are by definition non-thermoplastic and are preferably homopolymers or statistical copolymers.

[0017] The term diene elastomer, which can be used in compositions according to the invention, is particularly understood to mean: - any homopolymer of a diene monomer, conjugated or not, having from 4 to 18 carbon atoms; - any copolymer of a diene, conjugated or not, having from 4 to 18 carbon atoms and at least one other monomer.

[0018] The other monomer may be an olefin or a diene, conjugated or not.

[0019] Suitable conjugated dienes are conjugated dienes having 4 to 12 carbon atoms, in particular 1,3-dienes, such as 1,3-butadiene and isoprene.

[0020] Suitable olefins include vinylaromatic compounds having 8 to 20 carbon atoms and aliphatic alpha-monoolefins having 3 to 12 carbon atoms.

[0021] Suitable examples of vinylaromatic compounds include styrene, ortho-, meta-, para-methylstyrene, the commercial mixture "vinyl-toluene", para-tert-butylstyrene.

[0022] Alpha-monoolefins are particularly suitable as aliphatic alpha- acyclic aliphatic monoolefins having from 3 to 12 carbon atoms.

[0023] More specifically, the diene elastomer is: - any homopolymer of a conjugated diene monomer, in particular any homopolymer obtained by polymerization of a conjugated diene monomer having 4 to 12 carbon atoms; - any copolymer obtained by copolymerization of one or more dienes conjugated together or with one or more vinylaromatic compounds having 8 to 20 carbon atoms; - a copolymer of isobutene and isoprene (butyl rubber), as well as halogenated versions, in particular chlorinated or brominated, of this type of copolymer. - any copolymer obtained by copolymerization of one or more dienes, conjugated or not, with an alpha-monoolefin.

[0024] Preferably, the diene elastomer is chosen from the group consisting of natural rubber (NR), isoprene synthetic elastomers, butadien synthetic elastomers and mixtures of these elastomers, preferably chosen from the group consisting of natural rubber, polyisoprene synthetic elastomers and mixtures thereof.

[0025] The term "isoprene synthetic elastomer" refers, in a known manner, to a homopolymer or copolymer of isoprene, in other words, a diene elastomer selected from the group consisting of synthetic polyisoprenes (IR), various isoprene copolymers, and mixtures of these elastomers. Among the isoprene copolymers, particular examples include isobutene-isoprene (butyl rubber - IIR) and isoprene-styrene (SIR) copolymers. This isoprene elastomer is preferably a synthetic cis-1,4 polyisoprene; more preferably, a synthetic polyisoprene having a cis-1,4 bonding percentage (molar %) greater than 90%, and even more preferably greater than 98%.

[0026] The term "butadiene elastomer" is understood to mean, in a known manner, a homopolymer or copolymer of butadiene, in particular a diene elastomer selected from the group consisting of polybutadienes (BR), the various copolymers of butadiene, and mixtures of these elastomers. Among the butadiene copolymers, mention will be made of, among others: in particular butadiene-styrene (SBR), isoprene-butadiene (BIR) or isoprene-butadiene-styrene (SBIR) copolymers.

[0027] The rubber composition of at least one working ply of the tire according to the invention may also contain, in small quantities, any type of synthetic elastomer other than diene, or even polymers other than elastomers, for example, thermoplastic polymers. Preferably, the rubber composition of at least one working ply of the tire according to the invention does not comprise any elastomer other than an elastomer selected from the group consisting of natural rubber, isoprene synthetic elastomers, and mixtures thereof. Reinforcing load

[0028] The tire according to the invention comprises at least one working layer comprising metallic reinforcement elements embedded in a rubber composition based on 10 to 70 parts by weight per hundred parts of elastomers, abbreviated pc, of reinforcing filler, said reinforcing filler comprising 2 to 60 pc of carbon black and 8 to 60 pc of inorganic reinforcing filler.

[0029] A reinforcing filler is known for its ability to strengthen a rubber composition usable for the manufacture of tires.

[0030] The tire rubber composition according to the invention comprises a blend of a carbon black reinforcing filler and an inorganic reinforcing filler. Indeed, the use of a filler blend, in combination with the other characteristics of the rubber composition, makes it possible to achieve a compromise between raw and cured properties that the use of a single type of filler, particularly a single inorganic filler, does not allow.

[0031] Any type of so-called reinforcing filler, known for its ability to reinforce a rubber composition usable in particular for the manufacture of tires, can be used, for example a filler such as carbon black and a reinforcing inorganic filler such as silica.

[0032] Preferably, the reinforcing filler consists of 2 to 60 parts carbon black and 8 to 60 parts inorganic reinforcing filler, and preferably includes at least 3 parts carbon black, preferably at least 4 parts carbon black, most preferably at least 5 parts carbon black, most preferably at least 7 parts carbon black.

[0033] All carbon blacks are suitable as carbon blacks, including those conventionally used in tires or their treads. Among the latter, particularly reinforcing carbon blacks of the 100, 200, and 300 series, or blacks of the 500, 600, or 700 series (ASTM D-1765-2017 grades), such as NI 15, N134, N234, N326, N330, N339, N347, N375, N550, N683, and N772, are suitable. These carbon blacks can be used in isolation, as commercially available, or in any other form, for example as a carrier for certain rubber additives used. Carbon blacks could, for example, already be incorporated into diene elastomer, particularly isoprene, in the form of a masterbatch (see, for example, applications WO97 / 36724-A2 or WO99 / 16600-A1).

[0034] The term "reinforcing inorganic filler" here refers to any inorganic or mineral filler, regardless of its color or origin (natural or synthetic), also called "white" filler, "light" filler, or even "non-black" filler (as opposed to carbon black), capable of reinforcing, on its own and 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.

[0035] Suitable inorganic reinforcing fillers include mineral fillers of the siliceous type, preferably silica (SiO2), or of the aluminous type, in particular alumina (Al2O3). The silica used may be any reinforcing silica known to those skilled in the art, in particular any precipitated or pyrogenated silica having a specific surface area BET and a specific surface area CTAB both less than 450 m2 / g, preferably in the range of 30 to 400 m2 / g, in particular 60 to 300 m2 / g.

[0036] Precipitated silica can be produced from raw materials derived from inorganic sand (silicon dioxide from inorganic sand), from recycled material such as glass, in particular soda-lime glass, or from bio-based raw materials such as organic waste from plants such as bamboo leaves, corn cobs, sugarcane bagasse, rice, wheat, mustard, in particular rice husks, wheat husks, mustard husks.

[0037] Any type of precipitated silica can 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 include the silicas described in applications WO03 / 016215-A1 and WO03 / 016387-A1. Among commercial HDS silicas, the following can be used: "Ultrasil® 5000GR", "Ultrasil® 7000GR" from Evonik, and "Zeosil® 1085GR", "Zeosil® 1115 MP", "Zeosil® 1165 MP", "Zeosil® Premium 200 MP", and "Zeosil® HRS 1200 MP" from Solvay. As non-HDS silica, the following commercial silicas can be used: "Ultrasil® VN2GR" and "Ultrasil® VN3GR" silicas from Evonik, "Zeosil® 175GR" silica from Solvay, and "Hi-Sil" silicas. EZ120G(-D)”, “Hi-Sil EZ160G(-D)”, “Hi-Sil EZ200G(-D)”, “Hi-Sil 243LD”, “Hi-Sil 210”, “Hi-Sil HDP 320G” from PPG.

[0038] As further examples of reinforcing inorganic fillers that can be used in the rubber compositions of the invention, mineral fillers of the aluminous type, in particular alumina (Al12O3), aluminum oxides, aluminum hydroxides, aluminosilicates, titanium oxides, silicon carbides or nitrides, all of the reinforcing type as described for example in applications WO99 / 28376-A2, WO00 / 73372-A1, WO02 / 053634-Al, WO2004 / 003067-A1, WO2004 / 056915-A2, US6610261-B1 and US6747087-B2, may also be cited. Examples include the aluminas “Baikalox A125” or “CR125” (Baïkowski company), “APA-100RDX” (Condéa), “Aluminoxid C” (Evonik) or “AKP-G015” (Sumitomo Chemicals).

[0039] Preferably, the reinforcing inorganic filler in the rubber composition of the invention is silica, preferably precipitated silica.

[0040] The physical state of the reinforcing inorganic filler is irrelevant, whether it is in the form of powder, microbeads, granules, or spheres, or any other suitable densified form. Of course, the term "reinforcing inorganic filler" also includes mixtures of different reinforcing inorganic fillers, particularly silicas as described above.

[0041] Those skilled in the art will understand that, in place of the inorganic reinforcing filler described above, a reinforcing filler of another nature could be used, provided that this reinforcing filler of another nature is coated with an inorganic layer such as silica, or has functional sites on its surface, particularly hydroxyl sites, requiring the use of a coupling agent to establish the bond between this reinforcing filler and the diene elastomer. Examples include carbon blacks partially or fully coated with silica, or carbon blacks modified with silica, such as, but not limited to, the "Ecoblack®" fillers of the CRX2000 series or the "CRX4000" series from Cabot Corporation.

[0042] A person skilled in the art will be able to adapt the total reinforcing load rate according to the use concerned, in particular according to the type of tire concerned, for example tire for motorcycle, for passenger vehicle or for utility vehicle such as van or heavy goods vehicle.

[0043] In the present exposition, the specific surface area BET is determined by gas adsorption using the Brunauer-Emmett-Teller method described in "The Journal of the American Chemical Society" (Vol. 60, page 309, February 1938), and more specifically according to a method adapted from standard NF ISO 5794-1, Annex E of June 2010 [multipoint volumetric method (5 points) - gas: nitrogen - degassing under vacuum: one hour at 160°C - relative pressure range p / po: 0.05 to 0.17].

[0044] For inorganic fillers such as silica for example, the specific surface area values ​​CT AB were determined according to standard NF ISO 5794-1, Annex G of June 2010. The process is based on the adsorption of CTAB (N-hexadecyl-N,N,N-trimethylammonium bromide) on the "external" surface of the reinforcing filler.

[0045] Preferably, the rubber composition of the tire working ply according to the invention comprises at least one coupling agent of the reinforcing inorganic filler to the diene elastomer, the content of coupling agent representing at most 10% by weight relative to the weight of the reinforcing inorganic filler.

[0046] To couple the inorganic reinforcing filler to the diene elastomer, a coupling agent (or bonding agent) is used in a well-known manner. This agent must be at least bifunctional and ensure sufficient chemical and / or physical connection between the inorganic filler (surface of its aggregates) and the diene elastomer. "Bifunctional" means 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 including a silicon atom, said first functional group being capable of interacting with the hydroxyl groups of an inorganic filler, and a second functional group including a sulfur atom, said second functional group being capable of interacting with the diene elastomer.

[0047] When used, the coupling agent content represents at most 10% by weight relative to the weight of the reinforcing inorganic filler. A higher content does not improve the raw / baked compromise of the compositions used in the tire according to the invention.

[0048] Preferably, the coupling agent of the reinforcing inorganic filler to the diene elastomer is chosen from polysulfide silanes, polyorganosiloxanes, mercaptosilanes, blocked mercaptosilanes, mercaptosilane dimers, blocked mercaptosilane dimers, mercaptosilane oligomers, blocked mercaptosilane oligomers and mixtures thereof.

[0049] More preferably still, the coupling agent of the reinforcing inorganic filler to the diene elastomer is a silane polysulfide.

[0050] In particular, polysulfide silanes, called "symmetric" or "asymmetric" depending on their particular structure, can be used, as described for example in applications WO03 / 002648 (or US 2005 / 016651) and WO03 / 002649 (or US 2005 / 016650).

[0051] Preferably, polysulfide silanes corresponding to the following general formula (II) are particularly suitable, without the following definition being limiting:

[0052] Z - A - Sx - A - Z (II),

[0053] in which: - x is an integer from 2 to 8 (preferably from 2 to 5); - the symbols A, identical or different, represent a divalent hydrocarbon radical (preferably an alkylene group in Cl-Cl 8 or an arylene group in C6-C12, more particularly an alkylene in CICI 0, notably in a C1-C4 alkylene, in particular propylene); - The symbols Z, whether identical or different, correspond to one of the three formulas below:

[0054] [Chem.l]

[0055] in which: - the Ra radicals, substituted or unsubstituted, identical or different from each other, represent an alkyl group in Cl-Cl8, a cycloalkyl group in C5-C18 or an aryl group in C6-C18 (preferably alkyl groups in Cl-C6, cyclohexyl or phenyl, in particular alkyl groups in C1-C4, more particularly methyl and / or ethyl). - the Rb radicals, substituted or unsubstituted, identical or different from each other, represent an alkoxyl group in Cl-Cl8 or a cycloalkoxyl group in C5-C18 (preferably a group chosen from the alkoxyls in C1-C8 and the cycloalkoxyls in C5-C8, more preferably a group chosen from the alkoxyls in C1-C4, in particular the methoxyl and the ethoxyl), or a hydroxyl group, or such that 2 Rb radicals represent a dialkoxyl group in C3-C18.

[0056] In the case of a mixture of polysulfurized alkoxysilanes corresponding to formula (II) above, in particular common commercially available mixtures, the average value of "x" is a fractional number preferably between 2 and 5, more preferably close to 4. But the rubber composition can also advantageously include, for example, disulfide alkoxysilanes (x = 2).

[0057] Examples of polysulfide silanes include, in particular, the polysulfides (especially disulfides, trisulfides or tetrasulfides) of bis-(alkoxyl(Cl-C4)-alkyl(Cl-C4)silyl-alkyl(Cl-C4)), such as, for example, the polysulfides of bis(3-trimethoxysilylpropyl) or bis(3-triethoxysilylpropyl). Among these compounds, the tetrasulfide of bis(3-triethoxysilylpropyl), abbreviated TESPT, with the formula [(C2H5O)3Si(CH2)3S2]2, or the disulfide of bis-(triethoxysilylpropyl), abbreviated TESPD, with the formula [(C2H5O)3Si(CH2)3S]2, are used in particular. We will also cite as preferential examples the polysulfides (in particular disulfides, trisulfides or tetrasulfides) of bis-(monoalkoxyl(Cl-C4)-dialkyl(Cl-C4)silylpropyl), more particularly the tetrasulfide of bis-monoethoxydimethylsilylpropyl as described in the aforementioned patent application WO02 / 083782 (or US7217751).

[0058] Preferably, the coupling agent of the reinforcing inorganic filler to the diene elastomer corresponds to the formula (II), x being an integer from 2 to 8 (preferably from 2 to 5), the symbols A, identical or different, represent an alkylene group in Cl-CIO, preferably an alkylene in C1-C4, more preferably propylene, the symbols Z, identical or different, correspond to the formula Si(Rb)3 with Rb, identical or different from each other, representing an alkoxyl group in Cl-C4, in particular methoxyl and ethoxyl.

[0059] More preferably, the coupling agent of the inorganic reinforcing filler to the diene elastomer is chosen from the group consisting of bis(triethoxysilylpropyl) tetrasulfide, bis(trimethoxysilylpropyl) tetrasulfide, bis-(triethoxysilylpropyl) disulfide and bis-(trimethoxysilylpropyl) disulfide, more preferably is chosen from the group consisting of bis(triethoxysilylpropyl) tetrasulfide and bis(trimethoxysilylpropyl) tetrasulfide.

[0060] By way of example of coupling agents other than a polysulfurized alkoxysilane, mention shall be made in particular of bifunctional POS (polyorganosiloxanes) or polysulfides of hydroxysilane (Rb = OH in formula I above) as described for example in patent applications WO02 / 30939-A1 (or US6774255-B1), WO02 / 31041-A1 (or US2004 / 051210-A1), and WO2007 / 061550-A1, or silanes or POS bearing azo-dicarbonyl functional groups, as described for example in patent applications WO2006 / 125532-A1, WO2006 / 125533-A1, WO2006 / 125534-A1.

[0061] By way of examples of other sulfided silanes, we will cite for example silanes bearing at least one thiol function (-SH) (called mercaptosilanes) and / or at least one blocked thiol function, such as for example "NXT-Silane" marketed by the company Momentive, the dimers or oligomers of these silanes, as described for example in patents or patent applications US6849754, WO99 / 09036, WO2006 / 023815, WO2007 / 098080, WO2007 / 98120, EP1994038, EP2079793, WO2010 / 072685 and WO2008 / 055986. Crosslinking system

[0062] The crosslinking system is a sulfur-based system. This is referred to as a vulcanization system. The sulfur can be supplied in any form, including molecular sulfur or a sulfur-donating agent. The crosslinking system also includes a metal oxide, optionally a vulcanization accelerator, and 0.1 to 4 parts per million of a metal stearate. The rubber composition comprises at most 0.4 parts per million of stearic acid. The metal oxide in the rubber composition is preferably zinc oxide.

[0063] The crosslinking system may also include guanidine derivatives (in particular diphenylguanidine) or known vulcanization retardants as vulcanization activators.

[0064] Sulfur is used at a rate of at least 4 parts per annum. Below this rate, the rubber composition less effectively meets the criteria required for a calendering composition of metallic elements.

[0065] Any compound capable of acting as a vulcanization accelerator for diene elastomers in the presence of sulfur can 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-cyclohexyl-2-benzothiazyl sulfenamide ("CBS"), N,N-dicyclohexyl-2-benzothiazyl sulfenamide ("DCBS"), N-ter-butyl-2-benzothiazyl sulfenamide ("TBBS"), N-ter-butyl-2-benzothiazyl sulfenimide ("TBSI"), tetrabenzylthiuram disulfide ("TBZTD"), zinc dibenzyldithiocarbamate ("ZBEC") and mixtures of these compounds.

[0066] The rubber composition comprises from 0.1 to 4 parts per annum of a metallic stearate. By metallic stearate is meant a stearate of a metal selected from zinc, magnesium, potassium, calcium, sodium, cobalt, and copper. In addition, the rubber composition comprises at most 0.4 parts per annum of stearic acid, preferably at most 0.2 parts per annum of stearic acid, and preferably does not comprise any stearic acid.

[0067] Surprisingly, the combination of the above-mentioned levels of metallic stearate with a rubber composition comprising a cutting of fillers and not comprising, or little, stearic acid makes it possible to obtain good adhesion properties without significantly affecting hysteretic properties.

[0068] Preferably, the metallic stearate is zinc stearate. This stearate provides particularly advantageous adhesion properties without altering the cooking properties of the compositions, thus facilitating their implementation. Various additives

[0069] The rubber composition of the tire according to the invention may also include all or some of the usual additives commonly used in elastomer compositions for the manufacture of tire treads, such as plasticizers or stretching oils, whether aromatic or non-aromatic, pigments, protective agents such as ozone-blocking waxes, chemical ozone detoxifiers, antioxidants, anti-fatigue agents, setting agents, and adhesion promoters such as cobalt salts. Preferably, the rubber composition of at least one working ply of the tire according to the invention also includes a cobalt salt selected from cobalt abietates, naphthenates, and cobalt acetylacetonates. Reinforcing element

[0070] The tire according to the invention comprises at least one working layer comprising metallic reinforcement elements embedded in a rubber composition.

[0071] The work mat is therefore a reinforced product comprising metallic reinforcing elements and a rubber composition, the composition having been able to react with the surface of the reinforcing elements during the different phases of manufacture of the reinforced product, in particular during the crosslinking of the composition or during the making of the reinforced product before crosslinking of the composition.

[0072] The metallic reinforcing elements are wire elements. By metallic, we mean that they are made of a metallic material. A wire element is an element extending along a principal direction, its dimension along the principal direction being much greater than its dimensions along directions perpendicular to the principal direction. A wire element is flexible, that is to say, it can be elastically wound.

[0073] The metal reinforcement elements are embedded in the rubber composition, i.e. totally surrounded by the composition, with the possible exception of the cut areas of the sheet.

[0074] According to a first embodiment, the metallic surface of the reinforcing elements is made of a different material from the rest of the reinforcing elements. In other words, the reinforcing elements are made of a metallic material that is at least partly, preferably totally covered by a metallic layer which constitutes the metallic surface.

[0075] According to a second variant of the invention, the metallic reinforcement elements are made of the same material, in which case the reinforcement elements are made of a metal that is identical to the metal of the metallic surface.

[0076] According to one embodiment of the invention, the metallic surface comprises a metal selected from the group consisting of iron, copper, zinc, tin, aluminum, cobalt, nickel, and alloys comprising at least one of these metals. The alloys may be, for example, binary or ternary alloys, such as steel, bronze, and brass. Preferably, the metal of the metallic surface is iron, copper, tin, zinc, or an alloy comprising at least one of these metals. More preferably, the metal of the metallic surface is steel, brass (Cu-Zn alloy), zinc, or bronze (Cu-Sn alloy); even more preferably, brass or steel; and most preferably, brass.

[0077] When the metallic surface is made of steel, the steel is preferably carbon steel or stainless steel. When the steel is carbon steel, its carbon content, by weight, is preferably between 0.01% and 1.2%, or between 0.05% and 1.2%, or even between 0.2% and 1.2%, in particular between 0.4% and 1.1%. When the steel is stainless steel, it preferably contains at least 11% chromium and at least 50% iron.

[0078] The metal reinforcement elements are arranged side by side along a main direction. Preparation of rubber compositions

[0079] The rubber composition implemented in the invention is manufactured in suitable mixers, using two successive preparation phases well known to those skilled in the art: - a first thermomechanical working or mixing phase (the so-called "non-productive" phase), which can be carried out in a single thermomechanical step during which all the necessary constituents are introduced into a suitable mixer such as a standard internal mixer (for example, a Banbury type mixer). These constituents include the diene elastomer(s), the reinforcing filler(s), including the reinforcing inorganic filler, the coupling agent for the reinforcing inorganic filler to the diene elastomer, the specific processing agent, and any other miscellaneous additives, with the exception of the crosslinking system. The incorporation of the reinforcing filler into the elastomer can be carried out in one or more stages by thermomechanical mixing. This is particularly relevant if the filler is already fully or partially incorporated into the elastomer in the form of a masterbatch. ('masterbatch' in English) as described for example in applications WO 97 / 36724 or WO 99 / 16600, it is the masterbatch which is directly mixed and where appropriate other elastomers or fillers present in the composition which are not in the form of masterbatch are incorporated, as well as any other miscellaneous additives other than the crosslinking system. - a second mechanical working phase (the 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 120°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 5 and 15 min.

[0080] The non-productive phase can be carried out at high temperature, up to a maximum temperature between 110°C and 200°C, preferably between 130°C and 185°C, for a duration generally between 2 and 10 minutes.

[0081] The final composition thus obtained is then calendered, for example, into a sheet or plate, particularly for laboratory characterization, or extruded into a semi-finished (or profile) rubber product. The rubber composition is calendered, and then the metallic reinforcement elements are embedded between two strips of rubber composition to form at least one working layer of the tire according to the invention.

[0082] The composition can be either in the raw state (before crosslinking or vulcanization), or in the cooked state (after crosslinking or vulcanization).

[0083] The crosslinking of the composition can be carried out in a manner known to those skilled in the art, for example at a temperature between 130°C and 200°C, under pressure. Pneumatic

[0084] A tire having a geometry of revolution about an axis of rotation, its geometry is usually described in a meridian plane containing the tire's axis of rotation. For a given meridian plane, the radial, axial, and circumferential directions respectively denote the directions perpendicular to the tire's axis of rotation, parallel to the tire's axis of rotation, and perpendicular to the meridian plane. By convention, the expressions "radially inside" and "radially outside" mean "closer to" and "farthest from" the tire's axis of rotation. "Axially inside" and "axially outside" mean "closer to" and "farthest from" the tire's equatorial plane. of the tire being the plane passing through the middle of the tire's rolling surface and perpendicular to the tire's axis of rotation.

[0085] The tire of the invention is preferably intended to equip passenger and SUV type motor vehicles (“Sport Utility Vehicles”).

[0086] In this application, "pneumatic" (in English "tire" or "tire") means a pneumatic or non-pneumatic tire.

[0087] By "pneumatic tire" is meant a tire intended to form a cavity by cooperating with a support element, for example a rim, this cavity being capable of being pressurized to a pressure greater than atmospheric pressure.

[0088] By contrast, a "non-pneumatic bandage" is understood to be a bandage that is not suitable for being pressurized.

[0089] Thus, a pneumatic tire usually comprises two beads intended to come into contact with a rim, a crown consisting of at least one crown reinforcement and a tread, two sidewalls, the tire being reinforced by a carcass reinforcement anchored in the two beads. The crown reinforcement includes at least one working layer comprising metallic reinforcing elements arranged parallel to each other and forming an angle of at least 10° with the circumferential plane.

[0090] The pneumatic tires according to the invention are intended to equip in particular vehicles of all types such as passenger vehicles, two-wheeled vehicles, heavy goods vehicles, agricultural vehicles, civil engineering vehicles or aircraft or, more generally, any rolling device.

[0091] A non-pneumatic tire is a toroidal body made of at least one polymeric material, designed to perform the function of a tire but without being subjected to inflation pressure. A non-pneumatic tire can be solid or hollow. A hollow non-pneumatic tire can contain air, but at atmospheric pressure; that is, it does not have the pneumatic rigidity provided by an inflation gas at a pressure higher than atmospheric pressure. Thus, a non-pneumatic tire usually comprises a base, designed, for example, for mounting on a rigid rim, a crown reinforcement, ensuring the connection with a tread, and a deformable structure, such as spokes, ribs, or dimples, this structure being arranged between the base and the crown. Such non-pneumatic tires do not necessarily include a sidewall. Non-pneumatic tires are described, for example, in documents WO 03 / 018332 and FR2898077.Non-pneumatic tires are intended for use on passenger vehicles or two-wheeled vehicles.

[0092] The invention relates to tires both in the raw state (that is to say, before cooking) and in the cooked state (that is to say, after vulcanization). Examples Preparation of rubber compositions

[0093] The following tests are carried out as follows: the diene elastomer, the reinforcing filler, and the various other ingredients, with the exception of the vulcanization system, are successively introduced into an internal mixer (final filling rate: approximately 70% by volume), the initial tank temperature of which is approximately 90 °C. A thermomechanical process (non-productive phase) is then carried out in a single step, lasting approximately 3 to 4 minutes in total, until a maximum "drop" temperature of 165 °C is reached.

[0094] The mixture thus obtained is recovered, cooled, and then sulfur and an accelerator (sulfenamide) are incorporated on a mixer (homo-finisher) at 30 °C, mixing everything (productive phase) for an appropriate time (for example between 5 and 12 min).

[0095] The crosslinking of the composition was carried out at a temperature of 160°C, under pressure for 10 to 15 min. Measurement methods Cooking time

[0096] The duration t90 is determined from a cooking rheogram at 60°C according to DIN 53529. The value alpha is determined according to the following calculation: alpha(t)=(C(t)-Cmin) / (Cmax-Cmin) where C is a torque from the rheogram and t is a time. t90 is the time such that alpha=0.90. Maximum temperature at 60°C

[0097] The dynamic loss tan(D) measured at 60°C is a dynamic property well known to those skilled in the art and measured on a Metravib VA4000 or DMA+450 type viscoelastic analyzer using specimens comprising a baked composition. The response of the specimens subjected to a sinusoidal alternating simple shear load at a frequency of 10 Hz is recorded under determined temperature conditions (here 60°C) according to ASTM DI349-99. A strain amplitude sweep is performed from 0.1% cc to 100% cc (forward cycle), then from 100% cc to 0.1% cc (reverse cycle), cc meaning peak-to-peak. The specimen is of cylindrical cross-section as described in ASTM D 5992-96 (version reapproved in 2011, originally approved in 1996) in Figure X2.1 (circular embodiment) and has a diameter of 10 mm [0 to +0.04 mm] and a thickness of 2 mm [1.83-2.33].The tangent tan(d) of the phase angle d between the force exerted on the sample and its displacement represents a dynamic loss and is equal to the ratio G” / G’. The maximum value of the tangent tan(d) of the phase angle d observed during the deformation feedback cycle is recorded. This is the value reported in the table. Membership

[0098] To carry out the adhesion test, 14 or 15 metal cables made up of two brass wires of 30 hundredths of a millimeter in diameter twisted together (referred to as "reinforcements" below) are cut to a minimum length of 200mm and introduced into a mold.

[0099] The mold comprises two linear sections, each consisting of 15 holes for the reinforcements. In one of these two sections, each hole terminates in a conical chamfer designed to create a conical rubber fillet where the reinforcement "enters" the rubber block. The geometric characteristics of this fillet are: angle with the reinforcement = 45°, diameter of the cone base = D, and height = DD, where D' corresponds to the diameter of the hole. The assembly composed of the reinforcements and Rubber will be labeled "test tube".

[0100] The 2 linear parts mentioned above are separated by a width L (L corresponding to the length of the reinforcement embedded in the rubber) and which meet at their ends to form a frame, creating a space of length 200mm, width L and thickness 7.4mm on either side of the reinforcements.

[0101] After positioning the reinforcements in the mold, the previously mentioned spaces are filled with raw rubber, which a person skilled in the art judges to be compliant from a quality point of view and placed at room temperature for more than 24 hours and less than 2 weeks. A rolling operation is carried out.

[0102] All the operations described above and subsequently are carried out in a room where the temperature is 23 + / - 5°C, the humidity < 90% and protected from direct sunlight.

[0103] The filled mold is then pressure-baked. The temperature and baking time are adapted to the intended test conditions and left to the discretion of a person skilled in the art; for example, in the present case, the test specimen is baked at 160°C for 15 minutes.

[0104] Once cooked, the test tube is immediately removed from the mold and cooled.

[0105] Within 30 minutes to 4 hours after cooling, the rubber block of the test specimen is placed in the fixed jaws of a tensile testing machine having a 5 kN force cell according to ISO 7500 / 1. The movable jaws clamp the reinforcement on the side with the conical fillet. Each reinforcement is pulled individually at a constant speed of 100 ± 5 mm / min.

[0106] Adhesion is thus determined by measuring the force required to tear the reinforcement off the baked rubber block.

[0107] The value of tan(d) is determined on a crosslinked mixture directly after manufacturing this mixture.

[0108] The adhesion value is determined on a crosslinked mixture, after this mixture has been aged in an oven for 14 days at a temperature of 40°C and a relative humidity of 60%.

[0109] The results are expressed as a base of 100, taking the value of the control as the reference.

[0110] For the values ​​of t90 and tan(d), the calculation is carried out as follows: value for composition i (base 100) = 100 + (measured value for the control composition - measured value for composition i) / (measured value for the control composition) x 100. For the adhesion values, the calculation is carried out as follows: value for composition i (base 100) = (measured value for composition i) / (measured value for the control composition) x 100.

[0111] A value greater than 100 therefore means a performance superior to that of the control.

[0112] The different compositions shown in Table 1 are prepared. Mixture T1 is the reference mixture for compositions C1, C2, and C3. Mixture T2 is the reference mixture for compositions C4, C5, and C6. Mixture T3 is the reference mixture for compositions C7 and C8. Mixture T4 is the reference mixture for composition C9. Mixture T5 is the reference mixture for composition C10. Each mixture C1 comprises a molar content of stearate equivalent to the molar content of stearic acid in its reference mixture.

[0113] It is observed that the use of a metallic stearate in a composition comprising both carbon black and silica improves the adhesion properties to metallic reinforcements without significant influence on hysteretic properties compared to mixtures comprising stearic acid.

[0114] It is observed that the specific use of zinc stearate substantially improves the adhesion properties to the metallic reinforcements while preserving the firing properties, without any significant influence on the hysteretic properties compared to mixtures containing stearic acid. These effects are not observed with other stearate salts. The mixtures can therefore be used simply, without altering the overall behavior of the crosslinked composition, while ensuring improved adhesion to the reinforcements.

[0115] In a mixture consisting only of silica, these effects are not observed.

[0116] [Table 1] Tl Cl C2 C3 T2 C4 C5 C6 T3 C7 C8 T4 09 T5 CIO NR (1} 100' 100 100 10O 100 100' 100 100 1GO 100 100 100 100 100 100 Carbon black (2i 30 30 30 30 30 30 .39 30 30 30 30' Silica (3) 20 20 20 20 20 20 20 20 20 20 20 50 50 50 50 Agent de couplage (4j 1,6' 1,6 1,5 1,5 1,6 1,6 1,6 1,6 1,6 1.6 4 4 d 4 DPG {5} 0.4 0.4 0.4 0.4 pi 4 0.4 0.4 0.4 0.4 0.4 0.4 1 1 1 i 6PPD (6) 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 acide steanque (7) 0.5 1.1 1.8 0.5 1.1 stearate of zinc {8} 0.6 1.2 2 0.3 1.2 stearate of magnesium (S) çê U 1.9 stearate of cobalt {10} 0.8 1.2 ZnO {11} g 8 8 8 8 8 8 S 8 8 8 8 8 8 S Sei de cobalt 02) 1 1 0.7 1 1 1 1 1 1 1 1 1 1 1 TBBS (13) 0.9 0.9 0.9 0.9 0.9 Ü.9 0.9 03 ■ 0;9 0.9 0.9 0.9 0.9 6.9 6.9 Soufre (14) 5 5.5 S 5 5 5 c 5 5 5 5 5 c Results (ICO base) t9O 100 103 109 107 100 101 100| 113 ICO 103 108 100 104 100 103 Results after baking 15 min at 160°C Tanfd) 60“C 100 97 99 100 100' 101 105 104 100 96 98 109 102 100 98 Results after baking after raw aging for 14 days then baking 15 min at 160°C Adhesion 100 140 114 137 100; 125 103 103 100 141 124 100 91 100| 90 . 1. Natural rubber 2. ASTM N326 grade carbon black (designation according to ASTM D-1765); 3. "Zeosil 1165 MP" from Solvay-Rhodia in the form of micropearls, CTAB 160 m2 / g, precipitated silica 4. Liquid silane triethoxysilylpropyltetrasulfide (TESPT) "Si69" from Evonik 5. Diphenylguanidine “Perkacit DPG” from Flexsys 6. N-(l,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine "Santaflex 6PPD" from the company Flexys 7. Stearic acid “Pristerene 4931” from the company Uniqema 8. Zinc stearate from the company "Baerlocher" 9. Magnesium stearate from the company "Sigma Aldrich" 10. Cobalt stearate from the company "Taekwang Fine Chemical Co" 11. Industrial grade zinc oxide from Umicore 12. Cobalt naphthenate, Product No. 60830 from Fluka 13. N-Tert-Butyl-2-Benzothiazole sulfenamide 14. Sulfur

Claims

Demands

1. A tire comprising at least one working layer comprising metallic reinforcing elements embedded in a rubber composition based on at least one diene elastomer, 10 to 70 parts by weight per hundred parts of elastomers, abbreviated pc, of reinforcing filler, said reinforcing filler comprising 2 to 60 pc of carbon black and 8 to 60 pc of inorganic reinforcing filler, at least 4 pc of sulfur, a metallic oxide, and 0.1 to 4 pc of a metallic stearate, said composition comprising at most 0.4 pc of stearic acid.

2. Pneumatic according to the preceding claim wherein the metallic stearate is zinc stearate.

3. Pneumatic according to any one of the preceding claims wherein the rubber composition of at least one working layer does not comprise stearic acid.

4. Pneumatic according to any one of the preceding claims wherein the metal oxide of the rubber composition of at least one working layer is zinc oxide.

5. Pneumatic according to any one of the preceding claims in which said rubber composition comprises at least one coupling agent of the inorganic filler reinforcing the diene elastomer.

6. Pneumatic according to any one of the preceding claims, wherein the diene elastomer of the rubber composition of at least one working ply is selected from the group consisting of natural rubber, isoprene synthetic elastomers, butadien synthetic elastomers and mixtures of these elastomers, preferably selected from the group consisting of natural rubber, isoprene synthetic elastomers and mixtures thereof.

7. Pneumatic according to any one of the preceding claims wherein said rubber composition also comprises a cobalt salt selected from cobalt abietates, naphthenates and cobalt acetylacetonates.

8. Pneumatic according to any one of the preceding claims, wherein the reinforcing filler of the rubber composition of at least one working layer consists of 2 to 60 parts per inch of carbon black and 8 to 60 parts per annum of reinforcing inorganic filler, and preferably includes at least 3 parts per annum of carbon black, preferably at least 4 parts per annum of carbon black, most preferably at least 5 parts per annum of carbon black, most preferably at least 7 parts per annum of carbon black.