Tyre for a vehicle comprising a carcass ply with improved deformability in the green state

Abstract

The invention relates to a tyre for a vehicle that comprises a carcass ply, the ply comprising a plurality of filamentary reinforcing elements which are substantially parallel to one another extending in a so-called longitudinal direction and regularly spaced at a pitch p measured in a so-called transverse direction, which is perpendicular to the longitudinal direction, the plurality of reinforcing elements being embedded in a rubber composition based on a butadiene elastomer and at most 65 phr of isoprene elastomer, at least 25 phr of an inorganic reinforcing filler, and a crosslinking system.

Description

[0001] VEHICLE TIRE WITH IMPROVED RAW DEFORMABILITY CARCASS PLY

[0002] Technical field of the invention

[0003] The present invention relates to the field of vehicle tires comprising layers including metallic or textile reinforcements embedded in a rubber composition.

[0004] Previous art

[0005] A vehicle tire typically comprises a crown, two sidewalls, and two ridges, with each sidewall connecting each ridge to the crown. Each ridge includes at least one circumferential reinforcement element, usually in the form of a bead.

[0006] The vehicle tire also includes a carcass reinforcement anchored in each bead and extending into each sidewall and the top. The carcass reinforcement typically comprises a single layer of carcass material, including a portion wrapped around each circumferential reinforcement element.

[0007] The crown comprises a tread designed to come into contact with the ground during tire movement, as well as a crown reinforcement arranged radially between the tread and the carcass reinforcement. The crown reinforcement includes a working reinforcement comprising at least one working plies.

[0008] The top reinforcement generally also includes a shrinkage reinforcement arranged radially outside the working reinforcement, the shrinkage reinforcement being axially delimited by two axial edges and comprising at least one shrinkage wire reinforcement element wound circumferentially helically so as to extend axially from one axial edge to the other axial edge of the shrinkage reinforcement along a principal direction of the or each shrinkage wire reinforcement element.

[0009] The performance of a vehicle tire, whether pneumatic (i.e., capable of supporting the vehicle's load by means of a pressurized gas) or non-pneumatic (i.e., capable of supporting the vehicle's load without the use of a pressurized gas, for example, by means of stays), is linked not only to the mechanical properties of the various components constituting the tire, but also to the correct adherence to the geometry and relative positioning of these different elements within the tire. During the manufacturing of the vehicle tire, the various components can be deformed to varying degrees, particularly during the so-called forming stage, in which different layers of rubber and plies assembled in a generally cylindrical shape are deformed to form a generally toroidal structure.In the case of a bandage as described in documents WO2019 / 122621 and WO2019 / 180367, the top reinforcement of which comprises a single working layer, the carcass layer may have further undergone deformation along the circumferential direction such that each wire reinforcement element of the carcass layer forms with the circumferential direction an angle, in absolute value, greater than or equal to 10°, preferably from 20° to 75° and more preferably from 35° to 70°, in the portion of the carcass layer extending axially to the radial perpendicular of the working layer.

[0010] When this angle is obtained by deformation of the carcass layer, for example by applying a shear stress, it is important that the gaps between the reinforcing elements of said carcass layer are maintained so that these reinforcing elements remain regularly spaced and can perform their function.

[0011] The coating mixture for the carcass layer must therefore be able to deform, while retaining properties that allow the carcass layer to be shaped before its incorporation into the bandage, and while retaining its properties once cross-linked.

[0012] Document EP 1 803 766 describes a calendering composition suitable for use as a carcass layer and exhibiting very good processability, evaluated by the Mooney of the composition, as well as good stiffness comprising at least 25 parts per cent of silica, a specific coupling agent and a natural rubber content of at least 85 parts per cent if rolling resistance properties are to be kept as low as possible.

[0013] US patent 2014 / 0166181 describes a tire comprising a carcass layer whose calendering composition includes at least 70 parts per cubic inch (ppc) of natural rubber, 20 to 100 parts per cubic inch (ppc) of silica, and an adhesive system. This composition may include, to achieve good processability, 15 to 25 parts per cubic inch (ppc) of polybutadiene.

[0014] Continuing its research, the applicant developed a vehicle tire comprising at least one carcass ply, said ply comprising a plurality of wire reinforcement elements, substantially parallel to each other, extending along a longitudinal direction and regularly spaced at a pitch p measured along a transverse direction, perpendicular to the longitudinal direction. The plurality of reinforcement elements are embedded in a rubber composition based on a butadiene elastomer and at most 65 parts per cubic centimeter of isoprene elastomer, at least 25 parts per cubic centimeter of a reinforcing inorganic filler, and a cross-linking system. This tire exhibits excellent performance, the carcass ply displaying low rolling resistance and good rigidity, while also possessing very good processability, and in particular deformability that allows for maintaining a regular spacing of the reinforcement elements.

[0015] Detailed description of the invention

[0016] The invention therefore relates to a vehicle tire comprising at least one carcass ply, preferably a single carcass ply, said ply comprising a plurality of wire reinforcement elements substantially parallel to each other extending along a direction called longitudinal and regularly spaced according to a pitch p measured along a direction called transverse, perpendicular to the longitudinal direction, the plurality of reinforcement elements being embedded in a rubber composition based on a butadiene elastomer and at most 65 parts isoprene elastomer, at least 25 parts of a reinforcing inorganic filler, and a crosslinking system.

[0017] Definitions

[0018] The carbon-containing compounds mentioned in the description can be of fossil origin or bio-based. In the latter case, they may be partially or entirely derived from biomass or obtained from renewable raw materials derived from biomass. Similarly, the compounds mentioned may also come from the recycling of previously used materials; that is, they may be partially or entirely produced through a recycling process, or obtained from raw materials themselves derived from a recycling process. This includes, in particular, polymers, plasticizers, fillers, etc.

[0019] Any range of values ​​designated by the expression "between a and b" represents the range of values ​​greater than "a" and less than "b" (i.e., excluding the bounds a and b), while any range of values ​​designated by the expression "from a to b" means the range of values ​​from "a" to "b" (i.e., including the strict bounds a and b). The abbreviation "pce" means parts by weight per hundred parts of elastomer (of the total elastomers if multiple elastomers are present).

[0020] The expression "based on" composition is meant in this description as a composition comprising the mixture and / or the in situ reaction product of the different constituents used, some of these basic constituents (for example the elastomer, the filler or the constituents of the vulcanization system or other additive conventionally used in a rubber composition intended for the manufacture of tires) being capable of, or intended to react with each other, at least in part, during the different manufacturing phases of the composition intended for the manufacture of vehicle tires.

[0021] Butadiene elastomer

[0022] The rubber composition of the carcass ply of the vehicle tire according to the invention has the essential characteristic of being based on a butadiene elastomer.

[0023] The term "butadiene elastomer" is commonly understood to mean a homopolymer or copolymer of butadiene, in particular a diene elastomer selected from the group consisting of polybutadienes (BR), the various butadiene copolymers, and mixtures of these elastomers. Among the butadiene copolymers, butadiene-styrene (SBR), isoprene-butadiene (BIR), and isoprene-butadiene-styrene (SBIR) copolymers are particularly noteworthy.

[0024] Preferably, the butadiene elastomer is chosen from the group consisting of polybutadienes, butadiene-styrene copolymers and their mixtures, and preferably is polybutadiene.

[0025] Isoprene elastomer

[0026] The rubber composition of the carcass ply of the vehicle tire according to the invention has the essential characteristic of being based on at most 65 parts per annum of isoprene elastomer.

[0027] By "isoprene elastomer" is meant a homopolymer or a copolymer of isoprene, in other words a diene elastomer chosen from the group consisting of natural rubber (NR) which can be plasticized or peptized, synthetic polyisoprenes (IR), the various isoprene copolymers, in particular isoprene-styrene copolymers (SIR), isoprene-butadiene copolymers (BIR) or isoprene-butadiene-styrene copolymers (SBIR), and mixtures of these elastomers.

[0028] Preferably, the isoprene elastomer is chosen from the group consisting of synthetic polyisoprenes, natural rubber, isoprene copolymers, and mixtures thereof, preferably from the group consisting of natural rubber, synthetic polyisoprenes comprising a cis 1,4 bond mass percentage of at least 90%, and more preferably at least 98%, relative to the mass of the isoprene elastomer and mixtures thereof. Most preferably, the isoprene elastomer is natural rubber. Above a content of 65% isoprene elastomer, and particularly above a content of 70% isoprene elastomer, the stress crystallization phenomena characteristic of isoprene elastomers make the rubber compositions less susceptible to significant deformation.

[0029] Preferably, the rubber composition of the composite according to the invention comprises at least 5 parts per annum of isoprenoid elastomer. Preferably, the proportion of isoprenoid elastomer in the rubber composition is greater than 20 parts per annum and less than or equal to 65 parts per annum, preferably ranging from 50 parts per annum to 65 parts per annum.

[0030] The presence of at least two elastomers, an isoprene elastomer and a butadien elastomer, makes it possible to obtain good properties in raw and cooked form, that is to say once the composition is cross-linked, and in particular to ensure both good breaking properties and a great capacity to deform.

[0031] Inorganic filler

[0032] The rubber composition of the carcass ply of the vehicle tire according to the invention is based on at least 25 parts per an inorganic reinforcing filler.

[0033] In this application, "reinforcing inorganic filler" should be understood by definition as any inorganic or mineral filler (regardless of its color and whether 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, without any other means than an intermediate coupling agent, a rubber composition intended for the manufacture of pneumatic tires, in other words, capable of replacing, in its reinforcing function, a conventional carbon black of pneumatic grade. Such a filler is generally characterized, in a known way, by the presence of hydroxyl groups (-OH) on its surface.

[0034] Suitable inorganic reinforcing fillers include mineral fillers of the siliceous type, in particular silica (SiOa), or of the aluminous type, in particular alumina (Al2O3).

[0035] Preferably, the reinforcing inorganic filler is silica. The silica used may be any reinforcing silica known to those skilled in the art, including any precipitated or fumed silica having a BET surface area and a CTAB specific surface area measured according to ASTM D3765, both less than 450 m² 2 / g, preferably from 30 to 400 m 2 / g. Examples of highly dispersible precipitated silicas (known as "HDS") include, for example, "Ultrasil 7000" and "Ultrasil 7005" silicas from Degussa, "Zeosil 1165MP", "1135MP" and "1115MP" silicas from Rhodia, "Hi-Sil EZ150G" silica from PPG, "Zeopol 8715", "8745" and "8755" silicas from Huber, and high specific surface area silicas as described in application WO 03 / 16837.

[0036] 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 highly dispersible siliceous and / or aluminous fillers.

[0037] The reinforcing inorganic filler used, particularly if it is silica, preferably has a CTAB surface area between 45 and 400 m² 2 / g, more preferably strictly greater than 150 m 2 / g.

[0038] Preferably, the rubber composition of the composite according to the invention comprises from 25 to 100 parts per liter of silica. The minimum content of 25 parts per liter allows for excellent performance in terms of durability for the vehicle tire according to the invention, durability being defined as the number of kilometers traveled under a given load and speed.

[0039] To couple the reinforcing inorganic filler to the elastomer, one can optionally use in a known manner a coupling agent (or bonding agent) at least bifunctional intended to ensure a sufficient connection, of a chemical and / or physical nature, between the inorganic filler (surface of its particles) and the elastomer, in particular organosilanes, or bifunctional polyorganosiloxanes.

[0040] When the reinforcing inorganic filler is silica, a coupling agent must be used. Therefore, silica without a coupling agent is not considered a reinforcing filler within the meaning of the present invention.

[0041] In particular, polysulfide silanes, described as "symmetric" or "asymmetric" depending on their particular structure, can be used, as described for example in applications W003 / 002648 (or US 2005 / 016651) and W003 / 002649 (or US 2005 / 016650).

[0042] Examples of polysulfurized 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 bis(3) polysulfides _ trimethoxysilylpropyl) or bis(3 _ triethoxysilylpropyl). Among these compounds, bis(3) tetrasulfide is used in particular. _triethoxysilylpropyl), abbreviated TESPT, with the formula [(C2H5O)3Si(CH2)3S2]2, or bis-(triethoxysilylpropyl) disulfide, abbreviated TESPD, with the formula [(C2H5O)3Si(CH2)3S]2. Polysulfides (particularly disulfides, trisulfides, or tetrasulfides) of bis-(triethoxysilylpropyl) should also be cited as preferred examples. _ (monoalkoxyl(Cl -C4)-dialkyl(Cl _ C 4) silylpropyl), more specifically bis-monoethoxydimethylsilylpropyl tetrasulfide as described in US patent application 2004 / 132880.

[0043] Examples of coupling agents other than polysulfurized alkoxysilane include bifunctional POS (polyorganosiloxanes) or hydroxysilane polysulfides as described in patent applications WO 02 / 30939 and WO 02 / 31041, or silanes or POS bearing azo'dicarbonyl functional groups, as described for example in patent applications WO 2006 / 125532, WO 2006 / 125533, WO 2006 / 125534.

[0044] In the rubber compositions of the carcass ply of the vehicle tire according to the invention, the coupling agent content is preferably in the range of 5 to 60% by weight relative to the amount of silica, preferably in the range of 15 to 50% by weight relative to the amount of silica, and most preferably in the range of 20 to 40% by weight relative to the amount of silica. These levels have proven particularly advantageous for obtaining the desired properties of the carcass ply rubber composition.

[0045] The rubber composition of the composite according to the invention may also include carbon black.

[0046] All carbon blacks are suitable, including those of the HAF, ISAF, and SAF types conventionally used in tires (so-called tire-grade blacks). Among these, carbon blacks of the 100, 200, or 300 series (ASTM grades) are particularly relevant, such as NI 15, N134, N234, N326, N330, N339, N347, and N375, or, depending on the intended application, blacks of higher series (e.g., N660, N683, N772). Carbon blacks could, for example, already be incorporated into an isoprene elastomer as a masterbatch (see, for example, applications WO 97 / 36724 or WO 99 / 16600). The specific surface area BET of carbon blacks is measured according to standard D6556-10 [multipoint method (minimum 5 points) — gas: nitrogen - relative pressure range P / PO: 0.1 to 0.3].Preferably, the rubber composition of the composite according to the invention does not include carbon black, or includes less than 10 parts per annum, preferably less than 5 parts per annum.

[0047] Crosslinking system

[0048] The rubber composition of the carcass ply of the vehicle tire according to the invention includes a crosslinking system.

[0049] The crosslinking system may be based on sulfur, sulfur donors, peroxide, and / or bismaleimides. Preferably, the crosslinking system is a vulcanization system, i.e., a system based on sulfur (or a sulfur-donating agent) and a vulcanization accelerator. Any compound capable of acting as a vulcanization accelerator for diene elastomers in the presence of sulfur may be used, including thiazole-type accelerators and their derivatives, sulfenamide, thiuram, dithiocarbamate, dithiophosphate, thiourea, and xanthate-type accelerators. Examples of such accelerators include the following sulfenamide compounds: ■ N-cyclohexyl-2-benzothiazyl sulfenamide ("CBS"), N,N-dicyclohexyl-2-benzothiazyl sulfenamide ("DCBS"), N-ter-butyl-2-benzothiazyl sulfenamide ("TBBS") and mixtures of these compounds.

[0050] Sulfur is used at a preferential rate of between 0.3 and 10 parts per annum, more preferably between 0.3 and 5 parts per annum. The primary vulcanization accelerator is used at a preferential rate of between 0.5 and 10 parts per annum, more preferably between 0.5 and 5 parts per annum.

[0051] Preferably, the composite composition according to the invention comprises a metal oxide and a stearic acid derivative, the ratio of the metal oxide to stearic acid derivative, by weight, being greater than 2. This preferred ratio ensures good adhesion to the reinforcing element embedded in the rubber composition. The metal oxide is preferably zinc oxide.

[0052] The rubber composition of the carcass ply of the vehicle tire according to the invention preferably comprises a vulcanization accelerator. The vulcanization accelerator is used at a preferential rate such that the sulfur / vulcanization accelerator mass ratio is less than or equal to 5, preferably less than or equal to 4.

[0053] 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.

[0054] Crosslinking (or curing), where applicable vulcanization, is carried out in a known manner at a temperature generally between 130°C and 200°C, for a sufficient time which can vary for example between 5 and 90 min depending in particular on the curing temperature, the crosslinking system adopted and the crosslinking kinetics of the composition considered.

[0055] Various additives

[0056] The rubber composition of the composite according to the invention may also include all or part of the usual additives commonly used in elastomer compositions intended for use in a vehicle tire, conveyor belt or belt, such as processing agents, plasticizers, pigments, protective agents such as anti-ozone waxes, chemical anthrozonants, antioxidants.

[0057] Suitable plasticizers include all plasticizers conventionally used in tires. These include preferably non-aromatic or very weakly aromatic oils chosen from the group consisting of naphthenic oils, paraffinic oils, MES oils, TDAE oils, vegetable oils, ether plasticizers, and ester plasticizers.

[0058] Preferably, the rubber composition comprises less than 10 parts, preferably less than 5 parts, of plasticizer.

[0059] The rubber composition can be manufactured in suitable mixers, using two successive preparation phases according to a general procedure well known to those skilled in the art: a first thermo-mechanical working or mixing phase (sometimes referred to as the "non-productive" phase) at high temperature, up to a maximum temperature between 110°C and 190°C, preferably between 130°C and 180°C, followed by a second mechanical working phase (sometimes referred to as the "productive" phase) at a lower temperature, typically below 110°C, for example between 40°C and 100°C, a finishing phase during which sulfur or sulfur donor and vulcanization accelerator are incorporated.

[0060] As an example, the first (non-productive) phase is carried out in a single thermomechanical step during which all the necessary constituents, any additional processing agents, and other miscellaneous additives, with the exception of sulfur and the vulcanization accelerator, are introduced into a suitable mixer, such as a standard internal mixer. The total mixing time in this non-productive phase is preferably between 1 and 15 minutes. After the mixture obtained in the first non-productive phase has cooled, the sulfur and the vulcanization accelerator are then incorporated at a low temperature, generally in an external mixer such as a roller mixer. The mixture is then blended (productive phase) for a few minutes, for example, between 2 and 15 minutes.

[0061] The final composition thus obtained is then calendered, for example in the form of a sheet or plate, particularly for characterization in the laboratory, or extruded, for example to form a rubber profile used for the manufacture of semi-finished products such as a reinforcement layer for tires.

[0062] Reinforcing element

[0063] The rubber composition of the carcass ply of the vehicle tire according to the invention comprises a plurality of wire reinforcement elements substantially parallel to each other extending in a so-called longitudinal direction and regularly spaced according to a pitch p measured in a so-called transverse direction, perpendicular to the longitudinal direction, the plurality of reinforcement elements being embedded in the rubber composition.

[0064] By "embedded", we mean that the reinforcing element is totally covered by the rubber composition, with the possible exception of the composite cutting areas.

[0065] By wire reinforcement element, we mean an element enabling the mechanical reinforcement of a matrix in which this reinforcement element is intended to be embedded.

[0066] Each wire reinforcement element within the plurality of wire reinforcement elements can be metallic or textile. A wire element is defined as an element with a length at least 10 times greater than the longest dimension of its cross-section, regardless of the cross-section's shape (circular, elliptical, oblong, polygonal, including rectangular, square, or oval). In the case of a rectangular cross-section, the wire element is in the form of a strip.

[0067] A metallic wire element can be a basic metallic monofilament. Such a basic metallic monofilament comprises a steel core, optionally coated with one or more layers of a coating that may be metallic and / or based on a non-metallic adhesive composition. Thus, preferably, each wire reinforcement element in the plurality of wire reinforcement elements is a basic metallic monofilament or an assembly of several basic metallic monofilaments.

[0068] The metallic cladding comprises a metal selected from zinc, copper, tin, cobalt, and alloys of these metals. Examples of alloys of these metals include brass and bronze. The core steel is a carbon steel containing between 0.1% and 1.2% carbon by mass, a maximum of 11% chromium by mass, and less than 1% by mass of each of the following elements: manganese, silicon, aluminum, boron, cobalt, copper, molybdenum, nickel, niobium, titanium, tungsten, vanadium, zirconium, phosphorus, sulfur, and nitrogen. The remainder consists of iron and unavoidable impurities resulting from the manufacturing process. The steel may exhibit a pearlitic, ferritic, austenitic, bainitic, or martensitic microstructure, or a microstructure resulting from a mixture of these microstructures.

[0069] The elementary metallic monofilament exhibits a mechanical strength ranging from 1000 MPa to 5000 MPa. Such mechanical strengths correspond to the steel grades commonly encountered in the field of tires, namely, grades NT (Normal Tensile), HT (High Tensile), ST (Super Tensile), SHT (Super High Tensile), UT (Ultra Tensile), UHT (Ultra High Tensile) and MT (Mega Tensile). The use of high mechanical strengths potentially allows for improved reinforcement of the matrix in which the reinforcing element is intended to be embedded, and a reduction in the weight of the reinforced matrix.

[0070] In the case where the elementary metallic monofilament has a circular cross-section, the diameter of these elementary metallic monofilaments preferentially ranges from 0.05 mm to 0.50 mm.

[0071] A metallic wire element can be an assembly of several elementary metallic monofilaments as described above, assembled together in a helix, for example by cabling or twisting the elementary metallic monofilaments to form, for example, layered cables comprising several concentric layers of elementary metallic monofilaments or stranded cables, each strand comprising several concentric layers of elementary metallic monofilaments. Optionally, and as described in W02005071157, such a metallic wire element includes a layer based on a polymer composition, preferably a composition comprising an elastomer, this layer being disposed between two layers of elementary metallic monofilaments of the layered cable or of a strand of the stranded cable.

[0072] A textile fiber element can be a basic textile monofilament, optionally coated with one or more layers of an adhesive-based coating. This basic textile monofilament is obtained, for example, by melt spinning, solution spinning, or gel spinning. Each basic textile monofilament is made from an organic material, particularly a polymer, or an inorganic material, such as glass or carbon. Polymeric materials can be thermoplastic, such as aliphatic polyamides, particularly polyamide 6-6, and polyesters, particularly polyethylene terephthalate. Polymeric materials can be non-thermoplastic, such as aromatic polyamides, particularly aramid, and cellulose, both natural and synthetic, particularly rayon.

[0073] Preferably, each wire reinforcement element of the plurality of wire reinforcement elements comprises a textile wire element made of a thermoplastic or non-thermoplastic polymeric material.

[0074] A textile yarn element can be an assembly of several elementary textile monofilaments as defined above. In one variant, the assembly comprises 2 to 7 elementary textile monofilaments, each with a substantially circular cross-section and a diameter ranging, for example, from 0.10 mm to 0.50 mm. In a second variant, the assembly comprises more than 10 elementary textile monofilaments, preferably more than 100 elementary textile monofilaments, and more preferably more than 500 elementary textile monofilaments, each with a substantially circular cross-section and a diameter ranging, for example, from 2 m to 100 m. In both the first and second variants, the resulting assembly is commonly called a strand.

[0075] A textile fiber element can also be an assembly of several assemblies or strands as defined above. In one variant, the materials from which the elementary textile monofilaments of each assembly or strand are made are identical. In another variant, the materials from which the elementary textile monofilaments of each assembly or strand are made are different, the textile fiber element then being commonly called a hybrid textile fiber element. In one embodiment, whether in the case of a metallic or textile fiber element, the layer based on a non-metallic adhesive composition is formed by a layer of an adhesion primer to improve the adhesion of the fiber element, for example, to an elastomeric matrix.Such adhesion primers are those commonly used by professionals for pre-gluing certain textile fibers (particularly polyester fibers, such as PET, aramid, and aramid / nylon). For example, an epoxy-based primer, especially one based on polyglycerol polyglycidyl ether, can be used. A blocked isocyanate-based primer can also be used.

[0076] In another embodiment, whether for a metallic or textile wire element, the layer based on a non-metallic adhesive composition is formed by a layer based on a resin and an elastomer latex. Examples include RFL (Resorcinol-Formaldehyde-Latex) type adhesive compositions, as well as adhesive compositions as described in W02015118041.

[0077] In yet another embodiment, whether in the case of a metallic or textile wire element, there may be a layer of an adhesion primer as described above and coating the wire element, this layer of adhesion primer itself being coated with a layer based on a resin and a latex of one or more elastomers as described above.

[0078] In one embodiment, the reinforcement element comprises a wire element and optionally a sheath covering the wire element individually or several wire elements collectively. The sheath may comprise one or more layers, each layer being based on a polymer composition, for example a [thermoplastic] composition or [as described in WO2010 / 136389, W02010 / 105975, WO2011 / 012521, WO2011 / 051204, WO2012 / 016757, W02012 / 038340, WO2012 / 038341, WO2012 / 069346, WO2012 / 104279, W02012 / 104280 and W02012 / 104281]. In this embodiment, the polymer composition of each layer of the sheath is different from the composition based on the matrix in which the sheathed wire element(s) is intended to be embedded.

[0079] The reinforcing wire elements are arranged parallel to each other and embedded, for example by calendering, in the rubber compound. This results in a so-called straight sheet, in which the reinforcing wire elements are parallel to each other and parallel to a principal direction of the sheet. Then, if necessary, portions of each straight sheet are cut at a cutting angle and these portions are joined together to obtain a so-called angled sheet, in which the reinforcing wire elements are parallel to each other and form an angle with the principal direction of the angled sheet, the angle formed with the principal direction being equal to the cutting angle.

[0080] Vehicle bandage

[0081] The vehicle tire according to the invention comprises a top, two sides, and two ridges, each side connecting each ridge to the top. Each ridge includes at least one circumferential reinforcing element, generally in the form of a rod.

[0082] The vehicle tire according to the invention also includes a carcass reinforcement anchored in each bead and extending into each sidewall and the top. The carcass reinforcement comprises a single layer of carcass including a portion wrapped around each circumferential reinforcement element.

[0083] The crown comprises a tread designed to come into contact with the ground during tire movement, as well as a crown reinforcement arranged radially between the tread and the carcass reinforcement. The crown reinforcement includes a working reinforcement comprising at least one working plies.

[0084] The top reinforcement also includes a shrinkage reinforcement arranged radially outside the working reinforcement, the shrinkage reinforcement being axially delimited by two axial edges and comprising at least one shrinkage wire reinforcement element wound circumferentially helically so as to extend axially from one axial edge to the other axial edge of the shrinkage reinforcement along a principal direction of the or each shrinkage wire reinforcement element.

[0085] Preferably, each wire reinforcement element of the plurality of substantially parallel wire reinforcement elements of the carcass ply of the vehicle tire according to the invention forms with the circumferential direction an angle, in absolute value, greater than or equal to 10°, preferably from 20° to 75° and more preferably from 35° to 70°, in the portion of the carcass ply extending axially to the radial vertical axis of the working ply.

[0086] In an embodiment allowing easy anchoring of the carcass reinforcement in each bead, each bead comprises at least one circumferential reinforcement element, a portion of the carcass ply being wrapped around each circumferential reinforcement element, the principal direction of each wire carcass reinforcement element forming, with the circumferential direction of the vehicle tire, an angle, in absolute value, strictly greater than 0°, preferably from 27° to 150° and more preferably from 56° to 123°, in the wrapped portion of the carcass ply.

[0087] The rubber composition of the carcass ply of the pneumatic tire according to the invention allows, in this particular arrangement where each wire reinforcement element of the plurality of wire reinforcement elements substantially parallel to each other of the carcass ply of the vehicle tire according to the invention forms with the circumferential direction an angle, in absolute value, greater than or equal to 10°, preferably from 20° to 75° and more preferably from 35° to 70°, in the portion of the carcass ply extending axially to the radial vertical of the working ply, allows to maintain a regular spacing between the wire reinforcement elements due to its good deformation properties, more homogeneous than with the compositions of the prior art.

[0088] Examples

[0089] Preparation of rubber compositions

[0090] Four rubber compositions, the detailed formulation of which is shown in Table 1, were prepared as follows ■

[0091] In an internal mixer (final fill level approximately 70% by volume), with an initial tank temperature of approximately 80°C, the elastomers, the organic or inorganic filler (carbon black or silica), and various other ingredients, with the exception of sulfur and the vulcanization accelerator, are successively introduced. A thermomechanical process (non-productive phase) is then carried out in a single step, lasting approximately 3 to 4 minutes, until a maximum "drop" temperature of 165°C is reached. The resulting mixture is collected, cooled, and then the sulfur and vulcanization accelerator are incorporated in a mixer (homo-finisher) at 30°C, mixing everything together (productive phase) for an appropriate time (for example, about ten minutes).

[0092] The compositions thus obtained are then calendered either in the form of plates (2 to 3mm thick) or thin sheets of rubber for the measurement of their physical or mechanical properties, or extruded to form, for example, a profile for a tire.

[0093] Tests and measurements: Measurement of Mooney viscosity (or Mooney plasticity)

[0094] An oscillating consistometer, as described in the French standard NF T 43005 (1991), is used. The Mooney plasticity measurement is performed according to the following principle: the raw (before firing) composition is molded in a cylindrical chamber heated to 100°C. After one minute of preheating, the rotor rotates within the specimen at 2 revolutions per minute, and the torque required to maintain this rotation is measured after 4 minutes of rotation. The Mooney plasticity (ML 1+4) is expressed in "Mooney units" (MU, with 1 MU = 0.83 Newton-meters). The lower the Mooney value, the lower the viscosity before firing and the better the processability of the composition.

[0095] Traction tests

[0096] The tests were carried out in accordance with the French standard NF T 46'002 of September 1988. All tensile measurements were carried out under normal temperature (23±2°C) and humidity (50±5% relative humidity) conditions, according to the French standard NF T 40'101 (December 1979).

[0097] We measured in second elongation (i.e. after accommodation) the nominal secant modulus calculated by reducing to the initial section of the specimen (or apparent stress, in MPa) at 10% elongation and at 100% elongation noted respectively MAio and MAioo on samples baked for 60 minutes at 150°C.

[0098] The stresses at break (in MPa) and the elongations at break (AR in %) were also measured at 23°C ± 2°C, according to the NF T 46'002 standard, on raw samples.

[0099] Dynamic properties (after cooking)

[0100] The dynamic properties tan(d)max at 23°C are measured on a viscoanalyzer (Metravib VA4000), according to ASTM D 5992-96. The response of a cross-linked sample (cylindrical specimen 4 mm thick and 400 mm long) is recorded. 2(of cross-section), subjected to a sinusoidal alternating simple shear load at a frequency of 10 Hz, under defined temperature conditions, for example, 23°C according to ASTM D 1349-99. A strain amplitude sweep is performed from 0.1 to 50% (forward cycle), then from 50% to 1% (return cycle). The results used are the loss factor tan(d) and the complex dynamic shear modulus G*. For the forward cycle, the complex dynamic shear modulus G*(10%) at 10% strain, at 23°C, is indicated. For the return cycle, the maximum observed value of tan(d), denoted tan(d)max, is indicated. It is recalled that, as is well known to those skilled in the art, the value of tan(d)max at 23°C is representative of the hysteresis of the material and therefore of its contribution to rolling resistance ■ the lower tan(d)max at 23°C is, the lower the rolling resistance and therefore the improved.

[0101] [Table 1]

[0102] (1) Natural rubber

[0103] (2) Neodymium Polybutadiene “Synteca 44” from Syntheos

[0104] (3) SBR with a Tg of -48°C as described in the examples of WO2015 / 185394 (4) Carbon black, ASTM grade N550

[0105] (5) Silica, “Zeosil 1165 MP” from Solvay, type HDS

[0106] (6) Coupling agent ■ “Si69” from Evonik — Degussa

[0107] (7) N-(1,3-Dimethylbutyl)'N'-phenyl-p-phenylenediamine (Santoflex 6) _ PPD") from Flexsys (8) Stearine, "Pristerene 4931" from Uniqema

[0108] (9) Zinc oxide, industrial grade — Umicore

[0109] (10) N-Cyclohexyl-2-benzothiazolesulfenamide (“Santocure CBS” from Flexsys)

[0110] (11) Diphenylguanidine, “Perkacit DPG” from Flexsys

[0111] It is observed that the compositions according to the invention exhibit, in their raw state, lower stresses while maintaining elongations at break and even improving cured stiffness, with a reduced contribution to hysteresis losses. After forming, a carcass sheet comprising the compositions according to the invention, having undergone shear deformation in the circumferential direction such that the reinforcing elements within the shear-deformed zone each form an angle, in absolute value, between 35° and 70° with the circumferential direction, exhibits wire reinforcement elements whose inter-wire spacing is better preserved than with compositions T1 and T2. This can undoubtedly be explained by the lower resistance to deformation of the mixtures according to the invention.

Claims

DEMANDS

1. Vehicle bandage comprising at least one carcass ply, said ply comprising a plurality of wire reinforcement elements substantially parallel to each other extending in a direction called longitudinal and regularly spaced in a pitch p measured in a direction called transverse, perpendicular to the longitudinal direction, the plurality of reinforcement elements being embedded in a rubber composition based on a butadiene elastomer and at most 65 parts per an isoprene elastomer, at least 25 parts per an inorganic reinforcing filler, and a crosslinking system.

2. Bandage according to the preceding claim wherein the butadiene elastomer is selected from the group consisting of polybutadienes, butadiene-styrene copolymers and mixtures thereof, and preferably is polybutadienes.

3. Bandage according to any one of the preceding claims wherein the isoprene elastomer is selected from the group consisting of natural rubber, synthetic polyisoprenes comprising a cis 1,4 bond mass ratio of at least 90% and mixtures thereof.

4. Bandage according to any one of the preceding claims wherein the reinforcing inorganic filler of the rubber composition is silica.

5. Bandage according to the preceding claim in which the rubber composition comprises from 25 to 100 parts per cent of silica.

6. Bandage according to claim 4 or 5 in which the silica has a CTAB surface area measured according to ASTM D3765 strictly greater than 150 m 2 / g.

7. Bandage according to any one of claims 4 to 6 wherein the rubber composition comprises a coupling agent having a content in the range of 5% to 60% by weight relative to the amount of silica, preferably in the range of 15% to 50% by weight relative to the amount of silica and preferably in the range of 20% to 40% by weight relative to the amount of silica.

8. Bandage according to any one of the preceding claims wherein the rubber composition does not comprise carbon black, or comprises less than 10 pc, preferably less than 5 pc.

9. Bandage according to any one of the preceding claims wherein each wire reinforcement element of the plurality of wire reinforcement elements comprises a textile or metallic wire element.

10. Bandage according to the preceding claim in which each wire reinforcement element of the plurality of wire reinforcement elements is a metallic elementary monofilament or an assembly of several metallic elementary monofilaments.

11. Bandage according to claim 9 wherein each wire reinforcement element of the plurality of wire reinforcement elements comprises a textile wire element made of a thermoplastic or non-thermoplastic polymeric material.

12. A tire according to any one of the preceding claims, wherein each wire reinforcement element of the plurality of substantially parallel wire reinforcement elements of the carcass ply of the vehicle tire according to the invention forms with the circumferential direction an angle, in absolute value, greater than or equal to 10°, preferably from 20° to 75° and more preferably from 35° to 70°, in the portion of the carcass ply extending axially to the radial perpendicularity of the working ply.

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