HARDENED PRODUCT CONTAINING AT LEAST ONE METAL HARDENING ELEMENT AND A RUBBER COMPOSITION

Description

Technical field of the invention

[0001] The present invention relates to the field of reinforced rubber products, in particular for pneumatic or non-pneumatic tires, as well as to articles comprising such reinforced products. Previous art

[0002] Reinforcing plies in tires or reinforced rubber products typically comprise a calendered rubber compound and textile or metallic reinforcing cords. Since these plies are subjected to significant stresses during tire operation, particularly due to potentially harsh driving conditions such as humid and corrosive environments, they must possess high durability, especially against the phenomenon of separation or cracking of the ends of the cross-laminated layers in the tire's shoulder area, a problem known as "cleavage." This requirement necessitates that the rubber compounds used in tire belt construction exhibit very high resistance to crack propagation and thermal oxidation, as well as appropriate breaking strength properties.

[0003] Numerous studies have been conducted by tire manufacturers to improve one or more of these performance characteristics, notably through the addition of additives to rubber compounds. For example, US patent 5,859,101 describes a tire compound comprising 0.05 to 5 parts per liter of a selected compound, including ascorbic acid and its derivatives, tocopherol, and citric acid and its derivatives, designed to improve the abrasion resistance, crack resistance, and fatigue resistance of rubber compounds suitable for calendering. This patent does not address the issue of adhesion to reinforcing elements.

[0004] Document EP3167110 discloses in-situ gummed cables in which the rubber composition includes an antioxidant such as ascorbic acid to improve the durability of the composition's adhesion to the metal reinforcement without degrading the initial adhesion.

[0005] US3903026 states that adding magnesium oxide to a composition containing cobalt carboxylate improves adhesion to a zinc-coated or zinc-alloy-coated metal reinforcement. The fracture properties of the compositions are not discussed.

[0006] Continuing her research, the applicant discovered that a rubber composition comprising an ascorbate compound and an alkaline earth metal exhibited both improved adhesion and resistance to crack propagation properties when the composition was used in calendering a metal reinforcement element, without degrading the fracture properties. Detailed description of the invention

[0007] The invention relates to a reinforced product, a finished or semi-finished article and a pneumatic or non-pneumatic bandage as defined in claims 1 to 15. Definitions

[0008] The expression "based on" refers to a product or composition containing the mixture and / or reaction product. in situ 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 product or composition may thus be in a totally or partially crosslinked state or in a non-crosslinked state.

[0009] By the expression "part by weight per hundred parts by weight of elastomer" (or pce), it is to be understood in the sense of the present invention, the part, by mass per hundred parts by mass of elastomer.

[0010] In this document, unless expressly stated otherwise, all percentages (%) shown 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 ​​going from more than a to less than b (that is, bounds a and b excluded) while any interval of values ​​designated by the expression "from a to b" means the domain of values ​​going from a to b (that is, including the strict bounds a and b).

[0012] The carbon-containing compounds mentioned in the description can be of fossil or bio-based origin. In the latter case, they may be partially or entirely derived from biomass or obtained from renewable raw materials derived from biomass. This includes, in particular, polymers, plasticizers, fillers, etc. Reinforced product

[0013] The reinforced product according to the invention is based on at least one metallic reinforcing element and a rubber composition based on at least one diene elastomer, a reinforcing filler and a sulfur-based crosslinking system, the rubber composition comprising at least one alkaline earth metal and an ascorbate compound of general formula (I): in which R 1 represents a hydrogen atom H, or a group selected from alkyl groups comprising from 1 to 18 carbon atoms, alkylcarbonyl and alkenyl groups comprising from 2 to 18 carbon atoms and alkenylcarbonyl groups comprising from 3 to 18 carbon atoms, the rubber composition having an ascorbate compound content of at least 0.5 pc and an ascorbate compound to alkaline earth metal molar ratio of 0.7 to 2.5.

[0014] An alkenyl group is understood to be a monovalent hydrocarbon group comprising at least one unsaturation. A carbonyl group is understood to be a divalent group -CO-. Ascorbate and alkaline earth metal

[0015] The rubber composition of the reinforced product according to the invention comprises at least one alkaline earth metal and an ascorbate compound of general formula (I), and has a content of ascorbate compound of general formula (I) of at least 0.5 pc and a molar ratio of ascorbate compound of general formula (I) to alkaline earth metal ranging from 0.7 to 2.5.

[0016] Alkaline earth metal is defined as a metal chosen from the group consisting of berillium, magnesium, calcium, strontium, barium and radium.

[0017] The molar ratio of ascorbate compound to alkaline earth metal in the rubber composition ranges from 0.7 to 2.5. In association with the other features of the invention, a molar ratio below 0.7 leads to weaker adhesive strength, while a ratio above 2.5 leads to a reduction in elongation at break.

[0018] The ascorbate compound of general formula (I) can be any type of ascorbate compound meeting this formula.

[0019] Preferably, the rubber composition of the reinforced product according to the invention comprises an ascorbate-based compound of general formula (II): A − n R 2 n + (II) in which R 2 represents a hydrogen atom or an alkaline earth metal, n is an integer equal to 1 or 2, and A represents an ascorbate compound of general formula (I).

[0020] Preferably, R1 represents a hydrogen atom or a group selected from alkyl groups comprising 1 to 5 carbon atoms, preferably 1 to 3 carbon atoms, alkylcarbonyl and alkenyl groups comprising 2 to 5 carbon atoms and preferably 2 to 4 carbon atoms, and alkenylcarbonyl groups comprising 3 to 5 carbon atoms and preferably 3 to 4 carbon atoms.

[0021] In particular, in one preferred arrangement, the R1 group is preferentially a group selected from alkyl groups comprising 1 to 5 carbon atoms, preferably 1 to 3 carbon atoms, and alkenyl groups comprising 2 to 5 carbon atoms, and preferably 2 to 4 carbon atoms. In another preferred arrangement, the R1 group is preferentially a group selected from alkylcarbonyl groups comprising 2 to 5 carbon atoms, and preferably 2 to 4 carbon atoms, and alkenylcarbonyl groups comprising 3 to 5 carbon atoms, and preferably 3 to 4 carbon atoms. In yet another preferred arrangement, R1 represents the hydrogen atom.

[0022] Group R2 is preferentially chosen from among the alkaline earth metals, and preferably chosen from among magnesium and calcium.

[0023] Preferably, the ascorbate compound is chosen from ascorbic acid, calcium ascorbate and magnesium ascorbate, preferably from magnesium ascorbate and calcium ascorbate, and preferably from calcium ascorbate.

[0024] Preferably, the ascorbate compound content of general formula (I) in the rubber composition is at most 3 parts per million (ppm). It has been observed that for an ascorbate compound content below 0.5 ppm, while the other features of the invention are maintained, adhesion and elongation at break performance are degraded. A content above 3 ppm can impact the processability of the compositions, resulting in a shorter curing time that must be taken into account when implementing the reinforced product. Thus, an ascorbate compound content of general formula (I) in the range of 0.5 to 3 ppm, preferably from 1 to 3 ppm, represents an excellent compromise between the properties in the raw state (i.e., before crosslinking) and the properties after curing.

[0025] The rubber composition of the reinforced product according to the invention preferably also comprises an oxide or hydroxide of an alkaline earth metal, more preferably an oxide of an alkaline earth metal. The alkaline earth metal included in the rubber composition of the reinforced product according to the invention is derived both from the ascorbate-based compound of general formula (II) when group R2 is selected from the alkaline earth metals and from the oxide or hydroxide of the alkaline earth metal when the latter is present in the rubber composition.

[0026] In a preferred arrangement, the rubber composition of the reinforced product according to the invention comprises ascorbic acid and an alkaline earth metal oxide, preferably selected from calcium oxide and magnesium oxide, and preferably being magnesium oxide, these combinations showing particularly advantageous performance.

[0027] In another preferred arrangement, the rubber composition of the reinforced product according to the invention comprises calcium ascorbate and magnesium oxide.

[0028] Preferably, the oxide of an alkaline earth metal is chosen from magnesium oxide, calcium oxide, and mixtures of these oxides.

[0029] Preferably, the alkaline earth metal included in the rubber composition of the reinforced product according to the invention is chosen from calcium and magnesium. Dienic elastomer

[0030] By "diene" elastomer (or indistinctly rubber), whether natural or synthetic, should 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).

[0031] These diene elastomers can be classified into two categories: "essentially unsaturated" or "essentially saturated." Generally, "essentially unsaturated" refers to a diene elastomer derived at least in part from conjugated diene monomers, with a proportion of diene-derived motifs or units (conjugated dienes) greater than 15% (mole percent); this is the case for diene elastomers such as butyl rubbers or diene-alpha-olefin copolymers. EPDM do not fall within the preceding definition and may be specifically described as "essentially saturated" diene elastomers (low or very low content of diene-derived motifs, always less than 15% by mole). The diene elastomers included in the composition according to the invention are preferably essentially unsaturated.

[0032] The term diene elastomer specifically refers to a type of elastomer suitable for use in compositions according to the invention: (a) any homopolymer of a conjugated or unconjugated diene monomer having from 4 to 18 carbon atoms; (b) any copolymer of a diene, conjugated or unconjugated, having from 4 to 18 carbon atoms and at least one other monomer.

[0033] The other monomer can be ethylene, an olefin or a diene, conjugated or not.

[0034] Suitable conjugated dienes are those having 4 to 12 carbon atoms, in particular 1,3-dienes, such as 1,3-butadiene and isoprene.

[0035] Suitable olefins include vinylaromatic compounds with 8 to 20 carbon atoms and aliphatic α-monoolefins with 3 to 12 carbon atoms.

[0036] Examples of suitable vinylaromatic compounds include styrene, ortho-, meta-, para-methylstyrene, the commercial "vinyl-toluene" mixture, and para-tert-butylstyrene.

[0037] As suitable for aliphatic α-monoolefins, acyclic aliphatic α-monoolefins with 3 to 18 carbon atoms are particularly suitable.

[0038] Preferably, the diene elastomer is chosen from the group consisting of polybutadienes (BR), natural rubber (NR), synthetic polyisoprenes (IR), butadiene copolymers, isoprene copolymers, and mixtures of these elastomers. Butadiene copolymers are particularly chosen from the group consisting of butadiene-styrene copolymers (SBR).

[0039] Preferably, the diene elastomer is an isoprene elastomer.

[0040] The term "isoprene elastomer" is commonly understood to mean a homopolymer or copolymer of isoprene, in other words, a diene elastomer selected from the group consisting of natural rubber (NR), synthetic polyisoprenes (IR), various isoprene copolymers, and mixtures of these elastomers. Among the isoprene copolymers, particular examples include isobutene-isoprene (butyl rubber - IIR), isoprene-styrene (SIR), isoprene-butadiene (BIR), and isoprene-butadiene-styrene (SBIR). This isoprene elastomer is preferably selected from the group consisting of natural rubber, synthetic cis-1,4 polyisoprenes, and mixtures thereof; among these synthetic polyisoprenes, polyisoprenes with a molar percentage of cis-1,4 bonds greater than 90% are preferred, and even more preferably greater than 98%.Preferably and according to any one of the arrangements herein, diene elastomer is natural rubber.

[0041] Preferably, the proportion of diene elastomer, preferably isoprene elastomer, preferably natural rubber, is 50 to 100 parts per cent, more preferably 70 to 100 parts per cent, even more preferably 80 to 100 parts per cent, and most preferably 90 to 100 parts per cent. In particular, the proportion of diene elastomer, preferably isoprene elastomer, preferably natural rubber, is most preferably 100 parts per cent.

[0042] Whether it contains a single diene elastomer or a mixture of several diene elastomers, the rubber composition according to the invention may also contain, in small amounts, any type of synthetic elastomer other than a diene elastomer, or even polymers other than elastomers, for example, thermoplastic polymers. Preferably, the rubber composition according to the invention contains no synthetic elastomer other than a diene elastomer or any polymer other than elastomers, or contains less than 20 parts per million, preferably less than 15 parts per million. Crosslinking system

[0043] The rubber composition of the reinforced product according to the invention comprises a sulfur-based crosslinking system. This is referred to as a vulcanization system.

[0044] Sulfur can be supplied in any form, including molecular sulfur or a sulfur-donating agent. At least one vulcanization accelerator is also preferably present, and optionally, various known vulcanization activators such as zinc oxide, stearic acid or equivalent compounds such as stearic acid salts and transition metal salts, guanidine derivatives (especially diphenylguanidine), or known vulcanization retardants may be used.

[0045] Sulfur is used at a preferential rate of between 0.5 and 12 parts per thousand (ppm), particularly between 1 and 10 ppm. The vulcanization accelerator is used at a preferential rate of between 0.5 and 10 ppm, more preferably between 0.5 and 5 ppm, and very preferably between 0.5 and 3 ppm.

[0046] Preferably, the rubber composition of the reinforced product according to the invention comprises at least 3 parts per million of zinc oxide, and preferably at least 5 parts per million of zinc oxide. Preferably, the rubber composition of the reinforced product according to the invention comprises at most 15 parts per million of zinc oxide, and preferably at most 12 parts per million of zinc oxide.

[0047] Any compound capable of acting as a vulcanization accelerator for diene elastomers in the presence of sulfur can be used as an accelerator, including thiazole-type accelerators and their derivatives, sulfenamide-type accelerators, thiurams, dithiocarbamates, dithiophosphates, thioureas and xanthates. 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. Reinforcing load

[0048] The rubber composition includes one or more reinforcing fillers.

[0049] Any type of so-called reinforcing filler can be used, known for its ability to strengthen a rubber composition usable in particular for the manufacture of tires, for example an organic filler such as carbon black, an inorganic filler such as silica or a mixture of these two types of fillers.

[0050] All carbon blacks are suitable, including those conventionally used in tires or their treads. Among these, particularly the reinforcing carbon blacks of the 100, 200, and 300 series, or the 500, 600, and 700 series (ASTM D-1765-2017 grades), such as N115, N134, N234, N326, N330, N339, N347, N375, N550, N683, and N772. These carbon blacks can be used on their own, as commercially available, or in other forms, for example, as a carrier for certain rubber compound additives. 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).Also suitable are carbon blacks from tire recycling such as blacks from pyrolysis of tire bands, such as Enviro CB P550 black from the 500 series produced by the Scandinavian company Enviro Systems.

[0051] Examples of organic fillers other than carbon blacks include functionalized polyvinyl organic fillers as described in applications WO2006 / 069792-A1, WO2006 / 069793-A1, WO2008 / 003434-A1 and WO2008 / 003435-A1.

[0052] 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 the need for an intermediate coupling agent, a rubber compound intended for tire manufacturing. As is known, some reinforcing inorganic fillers are characterized, in particular, by the presence of hydroxyl groups (-OH) on their surface.

[0053] Suitable inorganic reinforcing fillers include mineral fillers of the siliceous type, preferably silica (SiO₂), or of the aluminous type, particularly alumina (Al₂O₃). The silica used may be any reinforcing silica known to those skilled in the art, including any precipitated or fumed silica with a specific surface area (BET) and a specific surface area (CTAB) both below 450 m² / g, preferably within the range of 30 to 400 m² / g, and in particular from 60 to 300 m² / g. Any type of precipitated silica may be used, including 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 the commercial HDS silicas, one can notably use the silicas “Ulsil ®< 5000GR”, “Ulsil ®< 7000GR” from the company Evonik, the silicas “Zeosil ®< 1085GR”, “Zeosil ®< 1115 MP”, “Zeosil ®< 1165MP”, “Zeosil ®< Premium 200MP”, “Zeosil ®< HRS 1200 MP” from the Solvay Company. As non-HDS silica, the following commercial silicas may be used: “Ultrasil ®< VN2GR”, “Ultrasil ®< VN3GR” from Evonik, “Zeosil ®< 175GR” silica from Solvay, “Hi-Sil EZ120G(-D)”, “Hi-Sil EZ160G(-D)”, “Hi-Sil EZ200G(-D)”, “Hi-Sil 243LD”, “Hi-Sil 210”, “Hi-Sil HDP 320G” from PPG and “K-160” from Wilmar.

[0054] In this presentation, 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 the 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 w / in: 0.05 to 0.17].

[0055] For inorganic fillers such as silica, for example, the CTAB specific surface area values ​​were determined according to the NF ISO 5794-1 standard, 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.

[0056] For carbon blacks, the STSA specific surface area is determined according to ASTM D6556-2016.

[0057] Other examples of inorganic fillers that could be used in the rubber compositions of the invention may also be cited: mineral fillers of the aluminous type, in particular alumina (Al2O3), 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-A1, WO2004 / 003067-A1, WO2004 / 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).

[0058] The physical state of the reinforcing inorganic filler is irrelevant, whether it be in the form of powder, microbeads, granules, spheres, or any other suitable densified form. Of course, the term "reinforcing inorganic filler" also refers to mixtures of different reinforcing inorganic fillers, particularly silicas as described above.

[0059] A professional skilled in the art will know how to adjust the total reinforcing filler content according to the intended use, particularly the type of tire, for example, motorcycle tires, passenger car tires, or commercial vehicle tires such as vans or trucks. Preferably, the total reinforcing filler content (carbon black and / or inorganic reinforcing filler such as silica) is between 10 and 200 parts per cubic meter (ppc), more preferably between 25 and 180 ppc, the optimum being known to vary depending on the specific application.

[0060] To couple the reinforcing inorganic filler to the diene elastomer, a well-known coupling agent (or bonding agent) can be used to ensure sufficient chemical and / or physical connection between the inorganic filler (the surface of its particles) and the diene elastomer. Organosilanes or polyorganosiloxanes, at least bifunctional, are particularly suitable. "Bifunctional" refers to a compound possessing a first functional group capable of interacting with the inorganic filler and a second functional group capable of interacting with the diene elastomer.

[0061] For example, such a bifunctional compound may comprise a first functional group comprising a silicon atom, said first functional group being able to interact with the hydroxyl groups of an inorganic charge and a second functional group comprising a sulfur atom, said second functional group being able to interact with the diene elastomer.

[0062] Preferably, organosilanes are chosen from the group consisting of polysulfide organosilanes (symmetric or asymmetric) such as bis(3-triethoxysilylpropyl) tetrasulfide, abbreviated TESPT and marketed under the name "Si69" by Evonik, or bis-(triethoxysilylpropyl) disulfide, abbreviated TESPD and marketed under the name "Si75" by Evonik; polyorganosiloxanes; mercaptosilanes; and blocked mercaptosilanes, such as S-(3-(triethoxysilyl)propyl) octanethioate, marketed by Momentive under the name "NXT Silane". More preferably, the organosilane is a polysulfide organosilane.

[0063] The coupling agent content in the composition of the invention is preferably less than or equal to 35 parts per liter (ppm), it being understood that it is generally desirable to use as little as possible. Typically, the coupling agent content represents 0.5% to 15% by weight relative to the amount of reinforcing inorganic filler, preferably 5% to 15% by weight. Its content is preferably in the range of 0.5% to 20 parts per liter, more preferably in the range of 3% to 10%. This content is readily adjusted by a person skilled in the art according to the amount of reinforcing inorganic filler used in the composition of the invention.

[0064] 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. Additives

[0065] The rubber compositions of the reinforced product according to the invention may also include all or part of the usual additives and processing agents known to those skilled in the art and commonly used in rubber compositions for pneumatic tires, such as plasticizers (such as plasticizing oils and / or plasticizing resins), fillers (reinforcing or non-reinforcing / other than those mentioned above such as, for example, regenerated or devulcanized powders from the recycling of pneumatic tires), pigments, protective agents such as anti-ozone waxes, chemical anti-ozonants, antioxidants, anti-fatigue agents, reinforcing resins (such as described, for example, in application WO 02 / 10269), a crosslinking system, for example based on sulfur and other vulcanizing agents, and / or peroxide and / or bismaleimide.

[0066] The use of an ascorbate compound and an alkaline earth metal under the conditions of the invention minimizes the amount of cobalt salts present in the rubber composition of the reinforced product. Thus, in a preferred arrangement, the cobalt salt content in the rubber composition of the reinforced product according to the invention is in the range of 0.5 to 2 parts per million, preferably from 0.5 to 1 part per million. Reinforcing element

[0067] The reinforced product according to the invention is based on at least one metallic reinforcing element and a rubber composition.

[0068] The expression "based on at least one metallic reinforcing element and a rubber composition" means a reinforced product comprising the reinforcing element and said composition, the composition having been able to react with the surface of the reinforcing element during the different phases of manufacture of the reinforced product, in particular during the crosslinking of the composition or during the manufacture of the reinforced product before crosslinking of the composition.

[0069] The said metallic reinforcement element is a wire element. It can be entirely or partially metallic.

[0070] In a particular arrangement, said reinforcing element includes a metallic surface.

[0071] The metallic surface of the reinforcing element constitutes at least part, and preferably all, of the surface of said element and is intended to come into direct contact with the rubber composition. Preferably, the reinforcing element is metallic, that is to say, made of a metallic material.

[0072] The rubber compound coats at least part of the reinforcing element, preferably the entire element.

[0073] According to a first embodiment of the invention, the metallic surface of the reinforcing element is made of a material different from the rest of the reinforcing element. In other words, the reinforcing element is made of a material that is at least partially, preferably totally, covered by a metallic layer that constitutes the metallic surface. The material at least partially, preferably totally, covered by the metallic surface is metallic or non-metallic, preferably metallic.

[0074] According to a second variant of the invention, the reinforcing element is made of the same material, in which case the reinforcing element is made of a metal that is identical to the metal of the metallic surface.

[0075] The metallic surface can, for example, improve the implementation properties of the reinforcing element, or the usage properties of the reinforced product and / or the pneumatic tire itself, such as adhesion properties, corrosion resistance or resistance to aging.

[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] Since some metals are subject to oxidation when in contact with ambient air, the metal may be partially oxidized.

[0078] 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 is preferably between 0.01% and 1.2%, or between 0.05% and 1.2%, or between 0.2% and 1.2%, particularly between 0.4% and 1.1%. When the steel is stainless steel, it preferably contains at least 11% chromium and at least 50% iron.

[0079] The invention applies in particular to steels of the type steel cord normal resistance (called "NT") for "Normal Tensile ") or high resistance (called "HT" for " High Tensile "), the (second and third) carbon steel reinforcements then having a tensile strength (Rm) which is preferably greater than 2000 MPa, more preferably greater than 2500 MPa. The invention also applies to steels of the type steel cord to very high resistance (called "SHT") for "Super High Tensile "), ultra-high resistance (called "UHT" for "Ultra High Tensile"or "MT" for "Mega Tensile "), the (second and third) carbon steel reinforcements then having a tensile strength (Rm) which is preferably greater than 3000 MPa, more preferably greater than 3500 MPa. The total elongation at break (At) of these reinforcements, the sum of the elastic elongation and the plastic elongation, is preferably greater than 2.0%.

[0080] The measurements of breaking strength, breaking resistance noted Rm (in MPa) and elongation at break noted At (total elongation in %) are carried out in tension according to the ISO 6892 standard of 1984.

[0081] According to a preferred embodiment, the reinforced product of the invention comprises several reinforcing elements as defined above and a calendered rubber in which the reinforcing elements are embedded, the calendered rubber being the rubber composition of the reinforced product of the invention. In this embodiment, the reinforcing elements are generally arranged side by side along a principal direction. For a envisaged application in the tire industry, the reinforced product of the invention can therefore constitute a reinforcing reinforcement for the tire.

[0082] The reinforced product according to the invention can be in its raw state (before crosslinking of the rubber composition) or in its cured state (after crosslinking of the rubber composition). The reinforced product according to the invention is cured after the reinforcing element(s) have been brought into contact with the rubber composition.

[0083] The reinforced product according to the invention can be manufactured by a process which comprises the following steps: Prepare two layers of the rubber composition, sandwich the reinforcement element(s) between the two layers, and if necessary, bake the reinforced product according to the invention.

[0084] Alternatively, the reinforced product according to the invention can be manufactured by depositing the reinforcing element on a portion of a layer, the layer is then folded over itself to cover the reinforcing element which is thus sandwiched along its entire length or part of its length.

[0085] The layers can be produced by calendering. During the curing of the reinforced product according to the invention, the rubber composition is cross-linked.

[0086] When the reinforced product according to the invention is intended to be used as a reinforcing reinforcement in a pneumatic tire, the curing of the reinforced product according to the invention generally takes place during the curing of the tire. Finished or semi-finished article and pneumatic

[0087] The invention also relates to a finished or semi-finished article comprising a reinforced product according to the invention. The finished or semi-finished article may be any article comprising a reinforced product. Examples, without limitation, include balloons, conveyor belts, shoe soles, and pneumatic or non-pneumatic bandages.

[0088] The pneumatic or non-pneumatic bandage, another object of the invention, has as its essential characteristic the inclusion of the reinforced product according to the invention. The bandage may be in its raw state (before cross-linking of the rubber composition) or in its cured state (after cross-linking of the rubber composition). Generally, during the manufacture of the bandage, the reinforced product is deposited in its raw state (i.e., before cross-linking of the rubber composition) within the bandage structure prior to the curing stage.

[0089] The tire according to the invention comprises a reinforced layer made of a reinforced product according to the invention, preferably selected from carcass plies, crown plies, bead-fillers, and combinations of these reinforced layers. Furthermore, the rubber composition of the reinforced product according to the invention could be used as an inner layer in a pneumatic or non-pneumatic tire, an inner layer being a layer of the tire that is neither in contact with ambient air nor with the inflation gas. Such inner layers are, for example, crown-foot layers, decoupling layers, edge rubbers, and combinations of these inner layers. In the present context, "edge rubber" means a layer positioned within the tire directly in contact with the end of a reinforced layer, the end of a reinforcing element, or another edge rubber.

[0090] The invention relates particularly to tires intended to equip motor vehicles of the passenger car type, SUVs ("Sport Utility Vehicles"), or two wheels (in particular motorcycles), or aircraft, or even industrial vehicles chosen from among vans, "Heavy Goods Vehicles", i.e. metro, buses, road transport vehicles (trucks, tractors, trailers), off-road vehicles such as agricultural or civil engineering vehicles, and others.

[0091] Thus, the invention relates in particular to a pneumatic or non-pneumatic tire comprising a crown including a crown reinforcement formed of two crown layers of reinforcing elements and surmounted by a tread, two beads intended to come into contact with a rim each comprising a circumferential reinforcing element and two sidewalls each extending radially inwards from an axial end of the crown to the beads, said tire further comprising a carcass reinforcement anchored to each of the beads and extending from the beads through the sidewalls towards the crown, at least one of the two crown layers of reinforcing elements being made of a reinforced product according to the invention. Examples Preparation of rubber compositions

[0092] The following tests are conducted 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 fill level: approximately 70% by volume), with an initial tank temperature of approximately 60°C. A single-stage thermomechanical process (non-productive phase) is then carried out, lasting approximately 3 to 4 minutes in total, until a maximum "drop" temperature of 165°C is reached.

[0093] The mixture thus obtained is collected, 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).

[0094] The compositions thus obtained are then calendered into plates (2 to 3 mm thick) or thin sheets of rubber and then subjected to a baking step at 150°C for 25 min before measuring their physical or mechanical properties. Measurement methods Traction tests

[0095] These tensile tests determine the elastic stresses and breaking properties of rubber compounds. The tests were carried out in accordance with French standard NF T 46-002 of September 1988. Elongations at break (in %) are measured at 100°C.

[0096] The results are expressed on a scale of 100, with the value 100 assigned to the control composition T1. A result greater than 100 indicates that the composition of the example considered exhibits a greater elongation at break than the control. Adhesion test Preparing the test tubes

[0097] The rubber compositions thus prepared are used to make a composite in the form of a test specimen according to the following protocol.

[0098] The metal / rubber composite used in this test is a block of rubber compound, consisting of two plates measuring 200 mm by 12.5 mm and 3.5 mm thick, applied one on top of the other before curing; the resulting block is then 7 mm thick. During the preparation of this block, the reinforcements, for example twelve in number, are sandwiched between the two raw plates; only a specific length of reinforcement, for example 12.5 mm, is left exposed to come into contact with the rubber compound, to which this reinforcement will bond during curing; the remaining length of the reinforcements is insulated from the rubber compound (for example, using a plastic or metallic film) to prevent any adhesion outside the defined contact area.Each reinforcement passes through the rubber block from one side to the other, with at least one of its free ends being kept of sufficient length (at least 5 cm, for example between 5 and 10 cm) to allow subsequent pulling of the reinforcement.

[0099] Each metal reinforcement consists of 2 steel wires with 0.7% carbon, 30 / 100ths of a millimeter in diameter twisted together, the brass coating comprises 63% copper.

[0100] The block containing the twelve reinforcements is then placed in a suitable mold and then baked for 15 minutes at 160°C, under a pressure of approximately 11 bar.

[0101] After the block has been baked, the following accelerated aging conditions are applied, allowing the resistance of the samples to the combined action of heat and humidity to be determined: the rubber blocks are placed in an oven at a temperature of 55°C, for 28 days and under a relative humidity of 95%. Measurement of pull-out forces

[0102] After the cooking and aging described above, the block is cut into test specimens, each containing a reinforcement which is pulled out of the rubber block, using a tensile testing machine according to the method described in ASTM D 2229-02; the tensile speed is 100 mm / min; the adhesion is thus characterized by the force required to pull the reinforcement out of the test specimen, at a temperature of 60°C; the pull-out force represents the average of the 15 measurements corresponding to the 15 reinforcements of the composite.

[0103] The higher the force value, the greater the adhesion between the cable and the rubber compound. Results are expressed as a scale of 100 relative to a control specimen containing metallic reinforcements of the same type as the tested specimen and containing the "T1" rubber compound. A value higher than that of the control specimen, arbitrarily set at 100, indicates an improved result, i.e., a pull-out force greater than that of the control specimen. Resistance test has the propagation of cracks

[0104] The cracking rate was measured on test specimens of the T-1 to T-19 rubber compositions, using a type 381 cyclic fatigue machine (“Elastomer Test System”) from MTS, as explained below.

[0105] Crack resistance is measured using repeated tensile tests on a specimen that is initially prepared (after a first tensile cycle) and then notched. The tensile specimen consists of a parallelepiped-shaped rubber plate, for example, 1 to 2 mm thick, 130 to 170 mm long, and 10 to 15 mm wide. Each of the two lateral edges is covered lengthwise with a cylindrical rubber bead (5 mm diameter) to secure it in the jaws of the tensile testing machine. The specimens prepared in this way are tested after accelerated aging at 77 °C for 14 days in a ventilated chamber. The test was conducted in air at a temperature of 60 °C.After accommodation, three very fine notches, 15 to 20 mm long, are made with a razor blade at mid-width and aligned lengthwise along the specimen, one at each end and one in the center, before the test begins. At each tensile cycle, the specimen's strain rate is automatically adjusted to maintain a constant energy release rate (the amount of energy released during crack propagation) of approximately 1000 J / m². The crack propagation rate is measured and expressed in nanometers per cycle. A lower value indicates greater resistance to crack propagation.

[0106] The results are expressed as a base of 100 relative to the control rubber composition T1. A value lower than that of the control specimen indicates an improved result, i.e. a lower crack propagation rate than that of the control specimen. Measuring roasting time

[0107] Measurements are taken at 130°C on raw rubber composition, i.e., before curing or crosslinking, in accordance with French standard NF T 43-005 (1991). The evolution of the consistometric index over time allows the curing time of the rubber compositions to be determined, assessed according to the aforementioned standard by the parameter T5 (case of a large rotor), expressed in minutes, and defined as the time required to obtain an increase in the consistometric index (expressed in UM or Mooney Unit, with 1 UM = 0.83 Newton-meters) of 5 units above the minimum value measured for this index.

[0108] The results are expressed as a base of 100 relative to the control rubber composition T1. A value lower than that of the control specimen indicates a shorter roasting time than the control specimen.

[0109] The compositions of the different test specimens tested and the results obtained are presented in Table 1.

[0110] It is observed that only the test specimens conforming to the invention exhibit both better adhesion to the metallic reinforcement with pull-out forces greater than the control, while exhibiting preserved elongation at break and improved resistance to cracking.

Claims

1. Reinforced product based on at least one metallic reinforcing element and a rubber composition based on at least one diene elastomer, a reinforcing filler and a sulfur-based crosslinking system, the rubber composition comprising at least one alkaline-earth metal and one ascorbate compound of general formula (I): in which R1 represents a hydrogen atom H, or a group selected from alkyl groups comprising from 1 to 18 carbon atoms, alkylcarbonyl and alkenyl groups comprising from 2 to 18 carbon atoms, and alkenylcarbonyl groups comprising from 3 to 18 carbon atoms, the rubber composition having a content of ascorbate compound at least equal to 0.5 phr and a molar ratio of ascorbate compound to alkaline-earth metal ranging from 0.7 to 2.5.

2. Reinforced product according to the preceding claim, in which the rubber composition comprises an ascorbate-based compound of general formula (II): A − n R 2 n + (II) in which R2 represents a hydrogen atom or an alkaline-earth metal, n is an integer equal to 1 or 2, and A represents an ascorbate compound of general formula (I).

3. Reinforced product according to either one of the preceding claims, in which R1 represents a hydrogen atom or a group selected from alkyl groups comprising from 1 to 5 carbon atoms, preferentially from 1 to 3 carbon atoms, alkylcarbonyl and alkenyl groups comprising from 2 to 5 carbon atoms and preferably from 2 to 4 carbon atoms and alkenylcarbonyl groups comprising from 3 to 5 carbon atoms and preferably from 3 to 4 carbon atoms.

4. Reinforced product according to any one of the preceding claims, in which R1 represents a group selected from linear alkyl, alkenyl, alkylcarbonyl and alkenylcarbonyl groups.

5. Reinforced product according to Claim 1 or 2, in which R1 represents a hydrogen atom.

6. Reinforced product according to any one of Claims 2 to 5, in which R2 is selected from alkaline-earth metals, preferentially selected from magnesium and calcium.

7. Reinforced product according to Claim 1, in which the ascorbate compound is selected from ascorbic acid, calcium ascorbate and magnesium ascorbate, preferentially selected from magnesium ascorbate and calcium ascorbate and preferably is calcium ascorbate.

8. Reinforced product according to any one of the preceding claims, in which the rubber composition further comprises an oxide or hydroxide of an alkaline-earth metal, preferentially an oxide of an alkaline-earth metal.

9. Reinforced product according to the preceding claim, in which the oxide of an alkaline-earth metal is selected from magnesium oxide, calcium oxide and the mixture of these oxides.

10. Reinforced product according to Claim 1, in which the rubber composition comprises ascorbic acid and an alkaline-earth metal oxide, preferably selected from calcium oxide and magnesium oxide, and preferably being magnesium oxide.

11. Reinforced product according to any one of the preceding claims, in which the content of ascorbate compound of general formula (I) in the rubber composition is at most 3 phr, and preferably within the range of from 1 to 3 phr.

12. Reinforced product according to any one of the preceding claims, in which the reinforcing filler of the rubber composition comprises carbon black, silica or a mixture of carbon black and silica.

13. Reinforced product according to any one of the preceding claims, in which the rubber composition comprises a diene elastomer selected from the group consisting of polybutadienes, natural rubber, synthetic polyisoprenes, butadiene copolymers, isoprene copolymers, and mixtures of these elastomers.

14. Finished or semi-finished article comprising a reinforced product according to any one of Claims 1 to 13.

15. Pneumatic or non-pneumatic tyre comprising a reinforced product according to one of Claims 1 to 13.