Hybrid cord and tire having the same

Abstract

A tire for a vehicle wheel comprises a support structure and a tread band arranged in a radially outer position relative to the support structure. The support structure comprises a plurality of hybrid reinforcing cords (10), each hybrid reinforcing cord having a plurality of monofilament textile wires (20) twisted to at least one multifilament textile yarn (30). In any cross section of the hybrid reinforcing cord (10), at least a portion of at least one monofilament textile wire (20) of the plurality of monofilament textile wires (20) defines a first radially outer surface portion of the hybrid reinforcing cord (10), and at least a portion of the at least one multifilament textile yarn (30) defines a second radially outer surface portion of the hybrid reinforcing cord (10).

Description

Technical Field

[0001] The present invention relates to a tyre for a vehicle wheel.

[0002] The tire of the present invention is preferably a tire for wheels of sports cars, in particular high-performance cars and ultra-high-performance cars.

[0003] Tires for high-performance and ultra-high-performance vehicles are generally designated as "HP" or "UHP" tires, specifically those designed to reach speeds exceeding 200 km / h and up to 300 km / h. Examples of such tires are those classified as "T," "U," "H," "V," "Z," "W," and "Y" according to the ETRTO (European Tyre and Rim Technical Organisation) standards, as well as racing tires, particularly for high-displacement four-wheeled vehicles. Typically, tires belonging to this category have a cross-sectional width equal to or greater than 185 mm, preferably between 195 mm and 385 mm, and more preferably between 195 mm and 355 mm. Such tires are typically mounted on rims with a mounting diameter equal to or greater than 13 inches, preferably not greater than 24 inches, and more preferably between 16 inches and 23 inches.

[0004] However, the tire of the present invention can also be used in vehicles other than the above-mentioned automobiles, for example in high-performance sports motorcycles.

[0005] The tire of the invention comprises hybrid reinforcing cords, as defined hereinafter in this description. Background Art

[0006] Tires with reinforcement cords comprising textile filaments of different materials twisted together are described, for example, in US 7222481 B2, EP 3196343 A1, US 4343343 A1, EP 329590 A1. Summary of the Invention

[0007] Throughout the specification and the claims that follow, when reference is made to certain values ​​of certain angles, unless otherwise specified, these refer to absolute values, ie, both positive and negative values ​​relative to a reference direction or plane.

[0008] Additionally, when any range of values ​​between a minimum value and a maximum value is recited, unless expressly stated otherwise, the aforementioned minimum and maximum values ​​are intended to be included in the aforementioned range.

[0009] Hereinafter, the following definitions apply.

[0010] The term “equatorial plane” of the tire is used to denote the plane perpendicular to the tire's axis of rotation and which divides the tire into two symmetrical equal parts.

[0011] The terms "radial" and "axial" and the expressions "radially inside / outside" and "axially inside / outside" are used with reference to a direction substantially parallel to the equatorial plane of the tire and a direction substantially perpendicular to the equatorial plane of the tire, respectively, i.e. with reference to a direction substantially perpendicular to the axis of rotation of the tire and a direction substantially parallel to the axis of rotation of the tire, respectively.

[0012] The terms "circumferential" and "circumferentially" are used with reference to the annular extension of the tyre, ie with reference to the rolling direction of the tyre, which corresponds to a direction lying in a plane coinciding with or substantially parallel to the equatorial plane of the tyre.

[0013] The term "substantially axial direction" is used to denote a direction that is inclined at an angle comprised between about 70° and about 90° with respect to the equatorial plane of the tire.

[0014] The term "substantially circumferential direction" is used to denote a direction oriented at an angle of between about 0° and about 10° relative to the equatorial plane of the tire.

[0015] The term "elastomeric material" or "elastomer" is used to refer to a material comprising a vulcanizable natural or synthetic polymer and a reinforcing filler, wherein the material, at room temperature and after vulcanization, can be deformed by a force and can quickly and strongly recover its substantially original shape and size after the deforming force is removed (as defined in ASTM D1566-11 Standard Terminology Relating To Rubber).

[0016] The expression “reinforcement cord” or more simply “cord” is used to denote an element consisting of one or more elongated elements (also called “wires” or “yarns”) possibly coated or embedded in a matrix of elastomeric material.

[0017] In the following, the expression "wire" will be used to refer to a single elongated element consisting of a single textile filament (in which case the expression "monofilament textile wire" will also be used) or even of a metallic material, whereas the expression "yarn" will be used to refer to an elongated element consisting of an aggregate of multiple textile filaments (in which case the expression "multifilament textile yarn" will also be used).

[0018] Each filament can also be called a "fiber."

[0019] The yarn may have one or more "ends", wherein the term "end" is used to denote a bundle of filaments twisted together. Preferably, a single end or at least two ends twisted together are provided.

[0020] Textile reinforcing cords can be identified by symbols representing the textile material, the count of the fibers used and the number of ends forming the reinforcing cord. For example, a reinforcing cord with ends made of aramid (aromatic polyamide) identified as Ar1672 means a cord containing aramid fibers with a count of 1670 dTex formed by two ends twisted together.

[0021] The term "strand" is used to denote the combination of at least two wires or yarns, or the combination of at least one wire and at least one yarn, to form an elongated element intended to be twisted with at least one other elongated element to form at least part of a reinforcing cord.

[0022] The expression “hybrid reinforcement cord” is used to denote a reinforcement cord comprising at least one monofilament textile thread and at least one multifilament textile yarn, said monofilament textile thread and said multifilament textile yarn being made of the same textile material or of different textile materials.

[0023] With particular reference to textile reinforcement cords, the expression “non-hybrid reinforcement cord” is intended to denote a reinforcement cord comprising only monofilament textile threads or only multifilament textile yarns.

[0024] The term "diameter" of a reinforcing cord or wire or yarn is used to denote the diameter measured in accordance with the provisions of the BISFA E10 method (The International Bureau For The Standardization Of Man-Made Fibres, Internationally Agreed Methods For Testing Steel Tire Cords, 1995 edition).

[0025] In the context of yarns, the term "diameter" is used to denote the diameter of an ideal circle that circumscribes all the filaments that define the yarn.

[0026] The term "count" of a layer is used to denote the number of reinforcing cords per unit length provided in the layer. The count can be measured in cords / dm (number of cords per decimeter).

[0027] The term "linear density" or "count" of a cord or wire / yarn is used to denote the weight per unit length of the cord or wire / yarn. Linear density can be measured in dtex (grams per 10 km of length). According to the test prescribed by BISFA, the measurement of linear density refers to flat wire / yarn, where no twist is applied during the test step or twisting step. For example, refer to:

[0028] For aramid fiber (AR):

[0029] -Test Methods for Para-aramid Fiber Yarn, 2002 Edition,

[0030] -Determination of Linear Density-Chapter 6

[0031] - Determination of tensile properties - Chapter 7 - Test procedures - Paragraph 7.5 - Procedure with initial pre-stretching;

[0032] For Lyocell fibers:

[0033] -Determination of Linear Density-Chapter 6

[0034] - Test Methods for Viscose, Cupro, Acetate, Triacetate, and Lyocell Filament Yarns - 2007 Edition, Determination of Tensile Properties - Chapter 7 - Tensile Test Conditions: Oven Dry Test - Table 7.1 - Test Procedure - Paragraph 7.5 - Oven Dry Test on Relaxed Specimens - Subparagraph 7.5.2.4.

[0035] Tires for sports cars require excellent ground adhesion to effectively transfer the high drive torque they experience to the road, resulting in high thrust and effective braking. They must also be lightweight and responsive to the lateral forces they experience during cornering.

[0036] A tyre for a sports car generally comprises a radial carcass structure extending between opposing bead structures; a cross-belt structure arranged in a radially outer position relative to the carcass structure; a zero-degrees reinforcement layer arranged in a radially outer position relative to the cross-belt structure; and a tread band arranged in a radially outer position relative to the zero-degrees reinforcement layer.

[0037] The carcass structure is designed to provide the desired integrity and structural strength characteristics of the tire, while the belt structure, in addition to contributing to these integrity and structural strength characteristics, is also designed to transfer the lateral and longitudinal stresses to which the tire is subjected when in contact with the road during driving to the carcass structure, thereby providing the desired performance (i.e., grip, driving stability, controllability, directionality, road holding) and comfort of the tire. On the other hand, the zero-degree reinforcement layer is designed to limit radial deformation of the belt structure.

[0038] For these reasons, one or more reinforcement layers are provided in the carcass structure and the belt structure, each reinforcement layer comprising a plurality of reinforcement cords suitably inclined with respect to the circumferential or rolling direction, while in the zero-degree reinforcement layers reinforcement cords oriented substantially parallel to the circumferential or rolling direction are provided.

[0039] In the context of the general trend to reduce the emissions of carbon dioxide into the atmosphere, the Applicant has considered the problem of reducing the rolling resistance of its tyres, including tyres for sports cars.

[0040] The Applicant therefore thought of using as light as possible reinforcement cords in its tyres for sports cars.

[0041] For some time, the applicant has been producing and selling tires comprising particularly light reinforcing cords made of metallic material. Each such reinforcing cord comprises three steel wires twisted together, the diameter of each steel wire being equal to 0.175 mm.

[0042] The applicant has focused his attention on textile reinforcement cords.

[0043] The Applicant has observed that, depending solely on the type of elongated element used in the reinforcing cord (monofilament textile wire, multifilament textile yarn and / or possible combination of one or more of the above-mentioned wires with one or more of the above-mentioned yarns), it is possible to produce a variety of hybrid reinforcing cords having various properties so as to be theoretically suitable for use in the carcass structure and / or belt structure and / or zero-degree reinforcement layer of a tire for a sports car.

[0044] In particular, the Applicant has observed that, being of equal material and diameter, monofilament textile threads are better suited than multifilament textile yarns for withstanding compressive and bending stresses and for reducing hysteresis caused by mutual friction between threads and / or textile filaments, whereas multifilament textile yarns are better suited than monofilament textile threads for withstanding tensile stresses and for adhering to surrounding elastomeric materials.

[0045] However, the Applicant has also recognized that, in tires for any type of vehicle, it is essential to obtain good adhesion of the reinforcing cords to the surrounding elastomeric material. This leads to the use of reinforcing cords comprising multifilament textile yarns in tires, thereby also obtaining good resistance to the tensile stresses to which the reinforcing cords are typically subjected.

[0046] The applicant also believes that in order to reduce the hysteresis problem and also to provide the above-mentioned reinforcing cords with the desired resistance to compressive stresses and bending stresses to which the reinforcing cords are typically subjected, monofilament textile wires are more suitable, as described above.

[0047] The applicant has found that the above-mentioned contrasting needs can be met by manufacturing a hybrid reinforcing cord comprising more than one monofilament textile wire and twisting the monofilament textile wires with at least one multifilament textile yarn such that at least a portion of the radially outer surface of the hybrid reinforcing cord is defined by at least one of the monofilament textile wires and at least one other portion of the radially outer surface of the hybrid reinforcing cord is defined by at least one multifilament textile yarn.

[0048] Thus, in a first aspect thereof, the invention relates to a tyre for vehicle wheels, said tyre comprising a supporting structure and a tread band arranged in a radially outer position relative to the supporting structure.

[0049] Preferably, the support structure comprises a plurality of hybrid reinforcement cords.

[0050] Preferably, each of said hybrid reinforcement cords comprises a plurality of monofilament textile wires twisted to at least one multifilament textile yarn.

[0051] Preferably, in any cross-section of the hybrid reinforcement cord, at least a portion of the monofilament textile wires of the plurality of monofilament textile wires defines a first radially outer surface portion of the hybrid reinforcement cord.

[0052] Preferably, in any cross-section of the hybrid reinforcement cord, at least a portion of said at least one multifilament textile yarn defines a second radially outer surface portion of the hybrid reinforcement cord.

[0053] The applicant has discovered that the desired resistance to compressive and bending stresses and the desired reduction in hysteresis can be achieved by providing a plurality of monofilament textile threads in the hybrid reinforcing cord of the present invention, while the desired tensile strength can be achieved by providing at least one multifilament textile yarn. Furthermore, the monofilament textile threads and the multifilament textile yarn are arranged relative to each other such that the outer surface of the reinforcing cord is defined both by a portion of the at least one multifilament textile yarn and by a portion of the at least one monofilament textile thread, which makes it possible to achieve the desired results in terms of adhesion to the surrounding elastomeric material and reduction in hysteresis.

[0054] Furthermore, the twisting of the plurality of monofilament textile wires with the at least one multifilament textile yarn provides the hybrid reinforcement cord with good fatigue properties.

[0055] In a second aspect of the invention, the present invention relates to a hybrid reinforcement cord.

[0056] Preferably, the hybrid reinforcement cord comprises a plurality of monofilament textile wires and at least one multifilament textile yarn twisted to the plurality of monofilament textile wires.

[0057] Preferably, in any cross section of the hybrid reinforcing cord, at least a portion of the monofilament textile wires of the plurality of monofilament textile wires defines a first radially outer surface portion of the hybrid reinforcing cord, and at least a portion of the at least one multifilament textile yarn defines a second radially outer surface portion of the hybrid reinforcing cord.

[0058] The Applicant believes that the hybrid reinforcing cord described above can be used in tires for all types of vehicles requiring high performance, therefore not only in sports cars but also, for example, in sports motorcycles, achieving the advantages described above.

[0059] As discussed below, the applicant also believes that the hybrid reinforcement cords described above may be used in the carcass structure, also or only in the belt structure of the tire, and also or only in the zero-degree reinforcement layers.

[0060] The Applicant also believes that the above-mentioned hybrid reinforcing cords can also be used or used exclusively in other reinforcing components of the tire, such as in the tire reinforcing components described below and indicated as "fluffers" and "chafers", to replace traditional metal cords (thus offering advantages in terms of reducing the weight of the tire and the possibility of running a deflated tire without the risk of overheating the reinforcing cords) and traditional textile cords containing only multifilament textile yarns (thus offering advantages in terms of stiffness, fatigue resistance and performance).

[0061] Furthermore, the use of the above-described hybrid reinforcing cords in the belt structure of the tire reduces or completely eliminates the occurrence of interference phenomena with possible radio frequency identification (RFID) processes of the tire and / or signals emitted by possible sensors arranged inside the tire (e.g. pressure sensors and / or temperature sensors).

[0062] In at least one of the above aspects, the present invention may have at least one of the preferred features described below.

[0063] Preferably, the first radially outer surface portion is defined by at least a portion of at least two of the plurality of monofilament textile threads, in which case one or more of the plurality of monofilament textile threads are completely surrounded by the filaments of the multifilament textile yarn and the at least two monofilament textile threads.

[0064] However, alternative embodiments are envisioned wherein the first radially outer surface portion is defined by at least a portion of each of the plurality of monofilament textile threads.

[0065] In a particular embodiment, about 50% of the outer surface of the hybrid reinforcing cord is defined by at least a portion of the at least one multifilament textile yarn, and about 50% of the outer surface of the hybrid reinforcing cord is defined by at least a portion of at least one monofilament textile thread of the plurality of monofilament textile threads. This means that, considering the theoretical center of the reinforcing cord, the angular dimension of the first radially outer surface portion is substantially equal to the angular dimension of the second radially outer surface portion.

[0066] However, the angular dimension of the first radially outer surface portion may be larger or smaller than the angular dimension of the second radially outer surface portion, in the first case promoting adhesion at the expense of hysteresis, and in the second case promoting hysteresis at the expense of adhesion.

[0067] In a first embodiment, the plurality of monofilament textile wires are twisted together at a predetermined first twist length to form a strand of monofilament textile wire.

[0068] Preferably, said at least one multifilament textile yarn is twisted together with said strands of said monofilament textile wire at a predetermined second twist length.

[0069] In a second embodiment, at least one first monofilament textile wire of the plurality of monofilament textile wires is twisted together with the at least one multifilament textile yarn at a predetermined first twist length to form a strand of mono-multifilament textile wires.

[0070] Preferably, the above-mentioned lay length is greater than or equal to about 2 mm, more preferably greater than or equal to about 3 mm.

[0071] Preferably, the lay length is less than or equal to about 20 mm, more preferably less than or equal to about 10 mm.

[0072] In a preferred embodiment, the lay length is between about 2 mm and about 20 mm, preferably between about 3 mm and about 10 mm.

[0073] Preferably, at least one second monofilament textile wire of the plurality of monofilament textile wires is twisted together with the strands of the mono-multifilament textile wire at a predetermined second twist length.

[0074] In the above two embodiments, the first lay length may be equal to or different from the second lay length.

[0075] In some preferred embodiments, the first lay length is different from (greater than or less than) the second lay length.

[0076] In a further embodiment, each monofilament textile wire of the plurality of monofilament textile wires is twisted together with at least one other monofilament textile wire of the plurality of monofilament textile wires and with the at least one multifilament textile yarn at a predetermined twist length to form a strand of monofilament textile wires.

[0077] This lay length is preferably equal to the first lay length described above.

[0078] In all embodiments, each of the plurality of monofilament textile threads is preferably made of aliphatic polyamide fibers (e.g., nylon 6, nylon 6.6, nylon 4.6, nylon 4.10, nylon 10.10, nylon 11, nylon 12, nylon 6.10, nylon 6.12), polyester fibers (e.g., polybutylene terephthalate, polyethylene terephthalate, polyethylene isophthalate), polyaryletherketone fibers (e.g., polyetheretherketone), or mixtures thereof.

[0079] In all embodiments, the at least one multifilament textile yarn preferably comprises filaments made of aromatic polyamide fibers, aliphatic polyamide fibers (e.g., nylon 6, nylon 6.6, nylon 4.6, nylon 4.10, nylon 10.10, nylon 11, nylon 12, nylon 6.10, nylon 6.12), polyester fibers (e.g., polybutylene terephthalate, polyethylene terephthalate, polyethylene isophthalate), polyketone fibers, polyvinyl alcohol fibers, cellulosic fibers (e.g., rayon, lyocell fibers), glass fibers, carbon fibers, or mixtures thereof.

[0080] Preferably, each monofilament textile wire of the plurality of monofilament textile wires has a diameter greater than or equal to about 0.1 mm, more preferably greater than or equal to about 0.2 mm.

[0081] Preferably, the diameter is less than or equal to about 1 mm, more preferably less than or equal to about 0.5 mm.

[0082] In a preferred embodiment, the diameter is between about 0.1 mm and about 1 mm, preferably between about 0.2 mm and about 0.5 mm.

[0083] Preferably, said hybrid reinforcing cord comprises a number greater than or equal to two monofilament textile threads.

[0084] Preferably, the number of the aforementioned monofilament textile threads is less than 10, more preferably less than or equal to 8, even more preferably less than or equal to 6.

[0085] In a preferred embodiment, the number of the above-mentioned monofilament textile threads is between 2 and 10, more preferably between 2 and 8, even more preferably between 2 and 6, for example equal to 3 or 4.

[0086] Generally speaking, it is preferred that the greater the number of monofilament textile wires provided in the hybrid reinforcing cord, the smaller the diameter of the monofilament textile wires.

[0087] Preferably, the linear density of the at least one multifilament textile yarn is greater than or equal to about 400 dTex, more preferably greater than or equal to about 800 dTex.

[0088] Preferably, the linear density is less than or equal to about 4500 dTex, more preferably less than or equal to about 4000 dTex.

[0089] In a preferred embodiment, the linear density is between about 400 dTex and about 4500 dTex, preferably between about 800 dTex and about 4000 dTex.

[0090] Preferably, said hybrid reinforcing cord comprises a number greater than or equal to one multifilament textile yarn.

[0091] Preferably, the number of multifilament textile yarns is less than or equal to 4, more preferably less than or equal to 3, even more preferably less than or equal to 2.

[0092] Preferably, the number of multifilament textile yarns is between 1 and 4, more preferably between 1 and 3, even more preferably between 1 and 2, such as equal to 1.

[0093] In some embodiments, at least some of the hybrid reinforcement cords include at least one metal wire helically wound around the plurality of monofilament textile wires and the at least one multifilament textile yarn.

[0094] The aforementioned metal wires advantageously contribute to strengthening the reinforcing cords and to keeping the monofilament textile wires firmly twisted to the multifilament textile yarns.

[0095] The winding direction of the metal wire onto the assembly defined by the monofilament textile wire and the at least one multifilament textile yarn may be identical or inconsistent with the twist direction of the monofilament textile wire relative to the at least one multifilament textile yarn.

[0096] Preferably, the winding direction is opposite to the twisting direction.

[0097] Preferably, the metal wire is wound on the above-mentioned assembly with a winding pitch greater than about 2 mm, more preferably greater than about 3.5 mm.

[0098] Preferably, the metal wire is wound on the assembly at a winding pitch of less than about 10 mm, more preferably less than about 5 mm.

[0099] In a preferred embodiment, the metal wire is wound on the assembly at a winding pitch of between about 2 mm and about 10 mm, preferably between about 3.5 mm and about 5 mm.

[0100] Preferably, the diameter of the metal wire is greater than about 0.08 mm, more preferably greater than about 0.10 mm.

[0101] Preferably, the metal wire has a diameter of less than about 0.20 mm, more preferably less than about 0.15 mm.

[0102] Preferably, the diameter of the metal wire is between about 0.08 mm and about 0.20 mm, more preferably between about 0.10 mm and about 0.15 mm.

[0103] Preferably, hybrid reinforcement cords comprising the above-mentioned metal wires are used in the cross belt structure and / or the zero-degree belt layer and / or the above-mentioned reinforcement layer.

[0104] Preferably, the filaments of said at least one multifilament textile yarn are coated with an adhesive substance or subjected to a chemical or physical bonding treatment in order to further improve the adhesion to the elastomeric material in which said filaments are embedded or coated.

[0105] In some embodiments, the at least one multifilament textile yarn comprises at least one textile monofilament and a plurality of textile filaments.

[0106] In this case, in any cross section of the hybrid reinforcing cord, the at least one textile monofilament is at least partially bound between the textile filaments, for example partially or completely surrounded by the textile filaments.

[0107] Each monofilament textile wire may be twisted with itself at a predetermined first twist length.The Applicant has observed that such an arrangement may contribute to optimizing the fatigue performance of the reinforcement cord.

[0108] Preferably, said first lay length is equal to said lay length.In this way, the bonding of the monofilament textile threads between the filaments of the respective multifilament textile yarns is maximized to greatly benefit the adhesion of the hybrid reinforcement cord to the surrounding elastomeric material.

[0109] The at least one multifilament textile yarn may or may not be twisted with itself at a predetermined second twist length. When twisted with itself, the second twist length is preferably equal to the twist length. This is done to maximize the bonding of the monofilament textile threads between the filaments of the multifilament textile yarn.

[0110] Preferably, said supporting structure comprises a carcass structure comprising at least one carcass ply having opposite end edges associated with (e.g. turned about) respective annular anchoring structures so as to define respective bead structures on opposite sides relative to the equatorial plane of the tyre.

[0111] Preferably, said supporting structure comprises a cross-belt structure arranged in a radially external position with respect to the carcass structure and in a radially internal position with respect to the tread band.

[0112] Preferably, said plurality of hybrid reinforcing cords is arranged in said carcass structure and / or in said belt structure.

[0113] As an alternative to or in addition to the cross-belt structure, the support structure may also include a zero-degree reinforcement layer, which may include non-hybrid reinforcement cords, which preferably only include monofilament textile wires or multifilament textile yarns (for example, made of aramid, nylon), or the zero-degree reinforcement layer may include hybrid reinforcement cords of the above-mentioned type.

[0114] Preferably, said supporting structure comprises at least one reinforcing layer associated with said at least one carcass layer at or near a respective end edge, said plurality of hybrid reinforcing cords being arranged in said at least one reinforcing layer.

[0115] Preferably, said at least one reinforcing layer may be associated with said at least one carcass layer at or near a respective bead structure.

[0116] Preferably, said at least one reinforcing layer may be arranged between the respective end edge of said at least one carcass layer and the respective bead structure.

[0117] More preferably, said at least one reinforcing layer may at least partially surround said bead structure.Such a reinforcing layer is also denoted by the term "flipper".

[0118] Alternatively or additionally, said at least one reinforcing layer may be associated with a respective end edge of said at least one carcass layer, in an axially external position with respect to the respective annular anchoring structure.

[0119] More preferably, said at least one reinforcing layer may extend from said annular anchoring structure towards said tread band.Such a reinforcing layer is also denoted by the term "chafer".

[0120] The chafer may be arranged in an axially external position or in an axially internal position relative to the end edge of the at least one carcass layer. In the case where the carcass structure comprises a plurality of carcass layers (e.g. two), the chafer may be arranged between the respective end edges of the respective carcass layers.

[0121] In a preferred embodiment of the tire in which the plurality of hybrid reinforcing cords are arranged in a carcass structure, each of the hybrid reinforcing cords comprises: three monofilament textile threads made of nylon, each having a diameter equal to approximately 0.21 mm; and a multifilament textile yarn made of nylon having a linear density equal to approximately 1400 dTex. Such a tire is particularly suitable for use in high-performance and ultra-high-performance vehicles as defined above.

[0122] In a preferred embodiment of a tire in which the plurality of hybrid reinforcing cords are arranged in a cross-belt structure, each of the hybrid reinforcing cords comprises: three monofilament textile threads made of PET, each having a diameter equal to approximately 0.40 mm; and a multifilament textile yarn made of aramid, having a linear density equal to approximately 1100 dTex. Such a tire is particularly suitable for use in high-performance and ultra-high-performance vehicles as defined above.

[0123] In a preferred embodiment of a tire in which the plurality of hybrid reinforcing cords are arranged in a zero-degree belt layer, each of the hybrid reinforcing cords comprises two strands twisted together, each strand comprising: two monofilament textile threads made of PET, each having a diameter of approximately 0.20 mm; and a multifilament textile yarn made of aramid, twisted to the two strands, having a linear density of approximately 1100 dTex. Such a tire is also particularly suitable for use in high-performance and ultra-high-performance vehicles as defined above.

[0124] In preferred embodiments of the tire in which the plurality of hybrid reinforcing cords are arranged in the at least one reinforcing layer (eg, chafer or flipper), the hybrid reinforcing cords are the same as described above in the case of use in a cross-belt structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0125] Further features and advantages of the tire of the present invention will become more apparent from the following detailed description of preferred embodiments thereof with reference to the accompanying drawings, in which:

[0126] - Figure 1 is a schematic partial half cross-sectional view of a portion of a tire according to an embodiment of the present invention;

[0127] - Figure 2 is Figure 1 A schematic side view of a test piece of a first embodiment of a hybrid reinforcement cord used in a tire of FIG.

[0128] - Figure 3 yes Figure 2 A schematic enlarged view of a cross section of a hybrid reinforcement cord, the cross section being Figure 2 Taken on the section SS drawn in;

[0129] - Figure 4 is Figure 1 A schematic side view of a test piece of a second embodiment of a hybrid reinforcement cord for use in a tire;

[0130] - Figure 5 yes Figure 4 A schematic enlarged view of a cross section of a hybrid reinforcement cord, the cross section being Figure 4 Taken on the section SS drawn in;

[0131] - Figure 6 is Figure 1 Schematic side view of a test specimen of a second embodiment of a hybrid reinforcement cord for use in a tire. DETAILED DESCRIPTION

[0132] For simplicity, Figure 1Only a portion of an embodiment of a tyre 100 according to the invention is shown, the remaining portions, not shown, being substantially identical and arranged symmetrically with respect to the equatorial plane MM of the tyre.

[0133] Figure 1 The tire 100 shown is particularly an embodiment of a tire for a four-wheeled vehicle.

[0134] Preferably, the tire 100 is a HP or UHP tire for sports and / or high performance or ultra high performance cars.

[0135] exist Figure 1 , “a” denotes an axial direction, “c” denotes a radial direction, “MM” denotes an equatorial plane of the tire 100 , and “RR” denotes an axis of rotation of the tire 100 .

[0136] The tyre 100 comprises at least one supporting structure 100a and a tread band 109 of elastomeric material situated in a radially outer position relative to the supporting structure 100a.

[0137] The supporting structure 100 a comprises a carcass structure 101 comprising at least one carcass layer 111 .

[0138] In the following, for simplicity of presentation, reference will be made to an embodiment of a tire 100 comprising a single carcass layer 111. However, it will be understood that what has been described has analogous application in tires comprising more than one carcass layer.

[0139] The carcass layer 111 has axially opposite end edges engaged with respective annular anchoring structures 102, called bead cores, and possibly associated with an elastomeric filler 104. The region of the tyre 100 comprising the bead cores 102 and the possible elastomeric filler 104 forms an annular reinforcing structure 103, called “bead structure” and intended to allow the tyre 100 to be anchored on a corresponding mounting rim, not shown.

[0140] The carcass layer 111 comprises a plurality of reinforcing cords 10 ′ coated with an elastomeric material or embedded in a matrix of a crosslinked elastomeric material.

[0141] The carcass structure 101 is of radial type, ie the reinforcing cords 10 ′ are arranged in a plane containing the axis of rotation RR of the tyre 100 and substantially perpendicular to the equatorial plane MM of the tyre 100 .

[0142] Each annular reinforcing structure 103 is associated with the carcass structure 101 by folding back (or turning up) the opposite end edges of at least one carcass ply 111 around the bead core 102 and possibly the elastomeric filler 104 so as to form a so-called turnup 101a of the carcass structure 101 .

[0143] In one embodiment, the coupling between the carcass structure 101 and the annular reinforcing structure 103 can be achieved by applying a second carcass layer ( Figure 1 is performed using a CMOS process (not shown).

[0144] A wear strip 105 is arranged at each annular reinforcement structure 103 so as to surround the annular reinforcement structure 103 along its axially inner region, axially outer region, and radially inner region, so that when the tire 100 is mounted on a wheel rim, the wear strip is arranged between the annular reinforcement structure 103 and the rim. However, such a wear strip 105 may not be provided.

[0145] The support structure 100a comprises a cross-belt structure 106 situated in a radially outer position with respect to the carcass structure 101 , the cross-belt structure comprising at least two belt layers 106a, 106b arranged radially superimposed on each other.

[0146] The belt layers 106a, 106b each include a plurality of reinforcing cords 10a, 10b. These reinforcing cords 10a, 10b are oriented at an angle of about 15° to about 45°, preferably about 20° to about 40°, relative to the circumferential direction of the tire 100 or the equatorial plane MM of the tire 100. For example, this angle is about 30°.

[0147] The reinforcing cords 10a, 10b of the belt layers 106a, 106b are parallel to each other and have a cross orientation with respect to the reinforcing cords of the other belt layer 106b, 106a.

[0148] In ultra-high performance tires, the belt structure 106 can be an inverted cross-belt structure. This belt structure is made by placing at least one belt layer on a support element and inverting the opposite lateral end edges of the at least one belt layer. Preferably, the first belt layer is first placed on the support element, then the support element is radially expanded, followed by the second belt layer being placed on the first belt layer, and finally the opposite axial end edges of the first belt layer are inverted on the second belt layer to at least partially cover the second belt layer as the radially outermost layer. In some cases, a third belt layer can be placed on the second belt layer. Advantageously, the inversion of the axially opposite end edges of the belt layer on another belt layer arranged in a radially outer position gives the tire greater reactivity and responsiveness when entering a curve.

[0149] The support structure 100a comprises at least one zero-degree reinforcement layer 106c, generally referred to as a "zero-degree belt," in a radially outer position relative to the cross-belt structure 106. Said zero-degree reinforcement layer comprises reinforcing cords 10c oriented in a generally circumferential direction. Such reinforcing cords 10c thus form an angle of several degrees relative to the equatorial plane MM of the tire 100.

[0150] The reinforcing cords 10a, 10b, 10c are coated with an elastomeric material or embedded in a matrix of a cross-linked elastomeric material.

[0151] Like the other semi-finished products constituting the tyre 100 , the tread band 109 is made of elastomeric material and is applied in a radially outer position relative to the zero-degree reinforcement layer 106 c .

[0152] Respective sidewalls 108 made of elastomeric material are also applied to the side surfaces of the carcass structure 101 in an axially external position with respect to the carcass structure 101 itself. Each sidewall 108 extends from one of the lateral edges of the tread band 109 up to a respective annular reinforcing structure 103.

[0153] The wear strips 105 , if provided, extend at least as far as the respective side walls 108 .

[0154] In some specific embodiments, like the one shown and described herein, the stiffness of the sidewall 108 can be increased by providing a reinforcing layer 120 , or an additional strip-like insert, commonly referred to as a “flipper,” which has the function of increasing the stiffness and integrity of the annular reinforcement structure 103 and the sidewall 108 .

[0155] The flipper 120 is wound around the corresponding bead core 102 and the elastomeric filler 104 to at least partially surround the annular reinforcement structure 103. In particular, the flipper 120 surrounds the annular reinforcement structure 103 along its axially inner region, axially outer region and radially inner region.

[0156] The flipper 120 is arranged between the turned-up end edge of the carcass layer 111 and the respective annular reinforcing structure 103. Generally, the flipper 120 is in contact with the carcass layer 111 and with the annular reinforcing structure 103.

[0157] In some specific embodiments, like the one shown and described herein, the bead structure 103 may also include an additional reinforcement layer 121 or a protective strip, generally referred to by the term “chafer”, and which has the function of increasing the stiffness and integrity of the annular reinforcement structure 103 .

[0158] The chafer 121 is associated with a respective turned-up end edge of the carcass layer 111 in an axially external position with respect to the respective annular reinforcing structure 103 and extends radially towards the sidewall 108 and the tread band 109 .

[0159] The flipper 120 and the chafer 121 comprise reinforcing cords 10 d coated with an elastomeric material or embedded in a matrix of a cross-linked elastomeric material (in the figures, the reinforcing cords of the flipper 120 are not visible).

[0160] The tread band 109 has, in its radially outer position, a rolling surface 109a intended to contact the ground. The rolling surface 109a is formed with circumferential grooves ( Figure 1 Not shown), the circumferential groove is formed by a transverse notch ( Figure 1 ) are connected so as to define a plurality of blocks ( Figure 1 not shown).

[0161] An underlayer 107 is arranged between the cross belt structure 106 and the tread band 109 .

[0162] In some particular embodiments, like the one shown and described herein, a strip 110 composed of an elastomeric material, generally called a “mini-sidewall”, may optionally be provided in the connection zone between the sidewall 108 and the tread band 109. The mini-sidewall 110 is generally obtained by coextrusion with the tread band 109 and allows to improve the mechanical interaction between the tread band 109 and the sidewall 108.

[0163] Preferably, the end portions of the sidewalls 108 directly cover the lateral edges of the tread band 109 .

[0164] In the case of a tubeless tire, a rubber layer 112 , generally called a “liner”, may also be provided in a radially internal position relative to the carcass layer 111 , in order to provide the necessary impermeability for the inflation of the tire 100 .

[0165] At least some of the reinforcing cords 10' (preferably, all the reinforcing cords 10' provided in the carcass layer 111) and / or at least some of the reinforcing cords 10a, 10b (preferably, all the reinforcing cords 10a provided in the belt layer 106a and all the reinforcing cords 10b provided in the belt layer 106b, even in the case where the belt structure 106 is an inverted cross-belt structure) and / or at least some of the reinforcing cords 10c of the zero-degree reinforcing layer 106c and / or at least some of the reinforcing cords 10d of the flipper 120 and / or the chafer 121 are Figure 2-6 A hybrid reinforcing cord 10 of the type shown and described below.

[0166] Reference Figure 2 and Figure 3 , the hybrid reinforcing cord 10 includes three monofilament textile wires 20 twisted to each other and a multifilament textile yarn 30 twisted to the three monofilament textile wires 20 at a predetermined twist length and defined by a plurality of filaments 32 .

[0167] Preferably, the three monofilament textile threads 20 are identical. Therefore, only one of them will be described below.

[0168] The above-mentioned reinforcing cord 10 can be manufactured in various ways.

[0169] The first way provides for initially twisting three monofilament textile wires 20 at a twist pitch P1 to form a strand of monofilament textile wires 20. Thereafter, this strand is twisted together with a multifilament textile yarn 30 at a twist pitch P2, which may be equal to or different from the twist pitch P1.

[0170] The second method provides for initially twisting one or more of the monofilament textile wires 20 with the multifilament textile yarn 30 at a twist length P1 to form a strand of monofilament textile wires. Thereafter, the strand is twisted together with another monofilament textile wire 20 at a twist length P2, which may be equal to or different from the twist length P1.

[0171] The third way provides a single twisting operation, wherein each of the monofilament textile wires 20 is twisted together with other monofilament textile wires 20 and the multifilament textile yarn 30 at a predetermined twist length P1 to form strands of monofilament and multifilament textile wires.

[0172] exist Figure 2 and Figure 3 In the embodiment shown, in any cross section of the reinforcing cord 10 (e.g. Figure 3 cross-section), preferably in all cross-sections of the reinforcing cord 10, each monofilament textile thread 20 is arranged on the outside relative to the filaments 32 of the multifilament textile yarn 30.

[0173] The mutual arrangement of the monofilament textile wires 20 and the multifilament textile yarns 30 is such that a first radially outer surface portion of the hybrid reinforcing cord 10 is defined by a portion of each of the three monofilament textile wires 20 , and a second radially outer surface portion of the hybrid reinforcing cord 10 is defined by a portion of the multifilament textile yarns 30 .

[0174] For example, approximately 50% of the outer surface of the hybrid reinforcement cord 10 is defined by the multifilament textile yarns 30 , while the remaining approximately 50% is defined by the monofilament textile wires 20 .

[0175] exist Figure 2 and Figure 3In the example shown, each of the three monofilament textile threads 20 is in contact with two other monofilament textile threads, and only two of the three monofilament textile threads 20 are in contact with the multifilament textile yarn 30 .

[0176] The monofilament textile wire 20 and the multifilament textile yarn 30 extend in the longitudinal direction A, as shown in FIG. Figure 2 shown.

[0177] The lay pitch P1 is preferably between about 2 mm and about 20 mm, more preferably between about 3 mm and about 10 mm, for example equal to about 3.5 mm.

[0178] Each monofilament textile wire 20 is made of aliphatic polyamide (e.g., nylon 6, nylon 6.6, nylon 4.6, nylon 4.10, nylon 10.10, nylon 11, nylon 12, nylon 6.10, nylon 6.12) or polyester fiber (e.g., polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polyethylene isophthalate (PEI)) or polyaryletherketone fiber (e.g., polyetheretherketone (PEEK)) or a mixture thereof.

[0179] The filaments 32 of the multifilament textile yarn 30 are made of an assembly of aromatic polyamide fibers or aliphatic polyamide fibers (e.g., nylon 6, nylon 6.6, nylon 4.6, nylon 4.10, nylon 10.10, nylon 11, nylon 12, nylon 6.10, nylon 6.12) or polyester fibers (e.g., polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polyethylene isophthalate (PEI)) or polyketone fibers or polyvinyl alcohol fibers or cellulosic fibers (e.g., rayon or lyocell) or glass fibers or carbon fibers or any other mixture of the above fibers or mixed fibers containing two or more of the above materials. Such mixed fiber assemblies are hereinafter referred to as "blended fibers."

[0180] In the case of a "fiber blend," the fibers of the filaments 32 may, for example, include:

[0181] 50% of aramid with a linear density equal to about 1100 dTex and 50% of PET with a linear density equal to about 1100 dTex (this component is hereinafter indicated as “blend 2200 dTex”);

[0182] 43% of aramid with a linear density equal to about 840 dTex and 57% of PET with a linear density equal to about 1100 dTex (this component is hereinafter referred to as “blend 1940 dTex”);

[0183] 33% of aramid with a linear density equal to about 550 dTex and 67% of PET with a linear density equal to about 1100 dTex (this component is denoted hereinafter as “blend 1650 dTex”).

[0184] Regardless of the specific type of textile material used for the filaments 32 of the multifilament textile yarn 30, this material is appropriately surface bonded to provide sufficient adhesion to the surrounding elastomeric material. Typically, the bonding process can be performed by coating with an adhesive substance or by chemical or physical treatment.

[0185] For example, after the monofilament textile wires 20 and the multifilament textile yarns 30 have been twisted together, the bonding treatment is performed by immersing the hybrid reinforcing cord 10 in a solution containing a bonding substance.

[0186] Each monofilament textile wire 20 preferably has a diameter between about 0.1 mm and about 1 mm, more preferably between about 0.2 mm and about 0.5 mm, also depending on the material from which it is made and the area of ​​the tire 100 where the hybrid reinforcing cords 10 are arranged.

[0187] The multifilament textile yarn 30 preferably has a linear density comprised between about 400 dTex and about 4500 dTex, preferably between about 800 dTex and about 4000 dTex, also depending on the material from which it is made and the zone of the tire 100 in which the hybrid reinforcing cords 10 are arranged.

[0188] In a particular embodiment, only the reinforcing cord 10 ′, and not the reinforcing cords 10 a , 10 b , 10 c and 10 d , is a hybrid reinforcing cord 10 of the type described above; or vice versa.

[0189] In other particular embodiments, only the reinforcing cord 10a, and not the reinforcing cords 10', 10b, 10c, 10d, is a hybrid reinforcing cord 10 of the type described above; or vice versa.

[0190] In some embodiments, only the reinforcing cords 10a and / or 10b, but not the reinforcing cords 10', 10c and 10d, are hybrid reinforcing cords 10 of the type described above.

[0191] In other embodiments, only the reinforcing cord 10d, and not the reinforcing cords 10', 10a, 10b and / or 10c, is a hybrid reinforcing cord 10 of the type described above.

[0192] When the reinforcing cord 10d is a hybrid reinforcing cord 10 of the above-mentioned type, such a hybrid reinforcing cord 10 can be used only in the core wrapper 120 (if a core wrapper is provided and when no core wrapper is provided or a core wrapper is provided and the core wrapper includes non-hybrid reinforcing cords), used only in the core wrapper 121 (if a core wrapper is provided and when no core wrapper is provided or a core wrapper is provided and the core wrapper includes non-hybrid reinforcing cords), or used in both the core wrapper 120 and the core wrapper 121 (if both are provided).

[0193] Figure 4 and Figure 5 An embodiment of a hybrid reinforcement cord 10 is shown which differs from the previous figures only in that the multifilament textile yarn 30 comprises monofilament textile threads 31 bonded between filaments 32 .

[0194] Figure 6 An embodiment of a hybrid reinforcement cord 10 is shown which differs from the previous figures only in that it further comprises a metal wire 50 helically wound around a monofilament textile wire 20 twisted together with the multifilament textile yarn 30 .

[0195] In the illustrated embodiment, the winding direction of the metal wire 50 is opposite to the twisting direction of the monofilament textile wire 20 twisted together with the multifilament textile yarn 30 .

[0196] The winding of the metal wire 50 has a winding pitch preferably comprised between about 2 mm and about 10 mm, more preferably between about 3.5 mm and about 5 mm, for example equal to about 4 mm.

[0197] The Applicant has manufactured some samples of hybrid reinforcing cords 10 for use in the carcass structure 101 , the cross belt structure 106 , the zero-degree reinforcing layer 106 c and the reinforcement layers 120 , 121 of the tyre 100 of the present invention.

[0198] In order to Figure 1 For use in the carcass structure 101 of a tire 100 of the type shown, and therefore intended for use in high-performance and ultra-high-performance vehicles as defined above, a hybrid reinforcing cord 10 has been produced comprising three monofilament textile threads 20 made of nylon, each having a diameter of approximately 0.21 mm, twisted together with a multifilament textile yarn 30 made of nylon and having a linear density of approximately 1400 dTex. This reinforcing cord is briefly designated as: Ny 3×0.21 mm+Ny 1400 dTex.

[0199] In order to Figure 1For use in the cross-belt structure 106 of a tire 100 of the type shown, and therefore intended for use in high-performance and ultra-high-performance vehicles as defined above, a hybrid reinforcing cord 10 has been produced comprising three monofilament textile threads 20 made of PET and each having a diameter of approximately 0.40 mm, twisted together with a multifilament textile yarn 30 made of aramid and having a linear density of approximately 1100 dTex. This reinforcing cord is briefly identified as: PET 3×0.40 mm+Ar1100 dTex.

[0200] In order to Figure 1 For use in the zero-degree belt 106c of a tire 100 of the type shown, and therefore intended for use in high-performance and ultra-high-performance vehicles as defined above, a hybrid reinforcing cord 10 has been produced comprising two strands, each comprising two monofilament textile threads 20 made of PET and each having a diameter of approximately 0.20 mm, twisted together to form a multifilament textile yarn 30 made of aramid. The multifilament textile yarn 30 has a linear density of approximately 1100 dTex. This reinforcing cord is briefly designated as: PET 2×(2×0.20 mm)+Ar 1100 dTex.

[0201] The Applicant has also manufactured a reinforcing cord 10 for use in the reinforcing layer 120 or 121 of the tire 100. This reinforcing cord 10 has the same structure as described above with reference to the cross-belt structure 106 and is made of the same material.

[0202] Comparative testing

[0203] The applicant has carried out comparative tests on some of the reinforcing cords 10 described above with respect to conventional reinforcing cords currently used by the applicant and currently considered suitable for ensuring the desired driving properties and desired tire performance. Some of these tests are discussed below.

[0204] Tests were carried out to compare the hysteresis (energy dissipated after friction between the wires / filaments) of a 200 mm test piece of a hybrid reinforcing cord of the Ny 3×0.21 mm+Ny 1400 dTex type and the hysteresis of a 200 mm test piece of a conventional reinforcing cord made by twisting together two yarns of Nylon 1400 dTex (designated here: 2×Ny 1400 dTex).

[0205] The reinforcing cords of the two specimens have substantially the same weight and substantially the same volume, and the two specimens have substantially the same amount of elastomeric material. Therefore, the two specimens have substantially the same weight.

[0206] These test pieces were subjected to 100 cycles of traction and compression using a Zwick dynamometer, which applied stresses to them with loads increasing up to 12 N between a maximum elongation of 1.5% (equal to 3 mm) and a minimum elongation of 0.5% (equal to 1 mm), and a traction / compression application rate equal to 50 mm / min. The average of the measurements taken was given as an indicator of the energy dissipated, with a value equal to 2.05 for conventional reinforcing cords and 2.24 for hybrid reinforcing cords of the Ny 3×0.21 mm + Ny 1400 dTex type, thus confirming the superior hysteresis performance of the hybrid reinforcing cords of the invention relative to conventional reinforcing cords comprising only multifilament textile yarns. This confirms the desirability of using hybrid reinforcing cords of the Ny 3×0.21 mm + Ny 1400 dTex type in tire carcass structures.

[0207] The applicant also conducted comparative tests to measure the bending strength of hybrid reinforcing cords of the PET 3×0.40 mm + Ar 1100 dTex type and conventional reinforcing cords of the 3×0.175 mm type made of steel. To this end, test specimens made of vulcanized elastomeric material were manufactured, comprising a plurality of hybrid reinforcing cords of the PET 3×0.40 mm + Ar 1100 dTex type, with a count equal to 80 cords / dm (8 cords per centimeter), and test specimens made of vulcanized elastomeric material were manufactured, comprising a plurality of conventional reinforcing cords of the 3×0.175 mm type made of steel, with a count equal to 130 cords / dm (13 cords per centimeter).

[0208] The test specimen comprising hybrid reinforcing cords of the PET 3×0.40 mm+Ar 1100 dTex type had a thickness of elastomeric material equal to about 1.30 mm and a weight equal to about 1480 g / m 2 The weight of the test specimens containing conventional metal reinforcing cords had an elastomeric material thickness equal to about 0.80 mm and a weight equal to about 1470 g / m 2 weight.

[0209] The two test specimens were subjected to a ring compression test as follows: the test specimens were folded and welded to form respective rings with a diameter of 80 mm. Such test specimens were subjected to an initial pre-tension of 0.5 N and a compression of 25 mm, wherein the compression speed was 100 mm / min.

[0210] The maximum force withstood by the test specimens containing the PET 3×0.40 mm + Ar 1100 dTex hybrid reinforcing cord was approximately 0.95 N, while the maximum force withstood by the test specimens containing the conventional metal reinforcing cord was approximately 0.86 N, thus confirming that the hybrid reinforcing cord of the present invention has better performance in terms of bending stiffness than the conventional metal reinforcing cord. This confirms the desirability of using the PET 3×0.40 mm + Ar 1100 dTex hybrid reinforcing cord in the belt structure and chafer and / or flipper of the tire.

[0211] The Applicant has also carried out comparative tests to measure the resistance to compressive stress of a hybrid reinforcing cord of the PET 3×0.40 mm+Ar1100 dTex type and of a traditional reinforcing cord made of steel of the 3×0.175 mm type.

[0212] The Applicant has indeed observed that, among the stresses that can reduce the life of the reinforcement cords, dynamic compressive stresses are particularly relevant, with particular reference to the belt structure and the chafer and / or flipper. In particular, when subjected to repeated compressive stresses, the reinforcement cords used in the aforementioned structural components of the tire deform, forming corrugations that lead to "unraveling", i.e., to the separation of the individual wires / yarns, thus damaging the tire.

[0213] In order to evaluate the performance of the reinforcing cords with respect to the above-mentioned compressive stresses, two test specimens were produced, each comprising two strips of vulcanized elastomeric material, each strip comprising a plurality of parallel reinforcing cords and arranged inclined at an angle of about 30° relative to each other.

[0214] One of the two test specimens (hereinafter referred to as "test specimen A") comprised hybrid reinforcing cords of the PET 3×0.40 mm+Ar1100dTex type, with a count equal to 80 cords / dm (8 cords per centimeter), while the other test specimen (hereinafter referred to as "test specimen B") comprised conventional reinforcing cords made of steel of the 3×0.175 mm type, with a count equal to 130 cords / dm (13 cords per centimeter).

[0215] The thickness of the elastomer material of the test specimen A is equal to about 1.30 mm and the weight is equal to about 1480 g / m 2 , and the thickness of the elastomer material of the test specimen B is equal to about 0.80 mm and the weight is equal to about 1470 g / m 2 .

[0216] Both test specimens were cured at 170°C for 10 minutes and conditioned at room temperature for 16 hours.

[0217] Each of the two test specimens was subjected to bending / compression cycles in a De Mattia type testing machine until fracture occurred.

[0218] The endurance time of test specimen A is about 40% longer than that of test specimen B. This confirms the advisability of using hybrid reinforcing cords of the PET 3×0.40 mm+Ar 1100 dTex type in the belt structure and in the chafer and / or flipper of the tire.

[0219] In summary, the comparative tests discussed above highlight that, in the case of a substantially equal weight of a semi-finished product containing reinforcing cords:

[0220] - Hybrid reinforcing cords of the Ny 3×0.21mm+Ny 1400 type have better performance in terms of hysteresis than traditional reinforcing cords of the 2×Ny 1400dTex type and are therefore suitable for use in tire carcass structures;

[0221] -The PET 3×0.40mm+Ar 1100dTex type hybrid reinforcing cord has better performance in bending stiffness and compressive stress resistance than the 3×0.175mm type traditional reinforcing cord made of steel currently used in the belt structure and chafer and / or bead core wrap, and is therefore suitable for use in the belt structure and bead core wrap of the tire.

[0222] The present invention has been described with reference to some preferred embodiments. Various modifications may be made to the embodiments described above while still falling within the scope of protection of the invention as defined by the following claims.

Claims

1. A tyre (100) for a vehicle wheel, said tyre comprising a support structure (100a) and a tread band (109) arranged in a radially outer position relative to said support structure (100a), wherein The support structure (100a) includes a plurality of hybrid reinforcement cords (10), each hybrid reinforcement cord (10) having a plurality of monofilament textile wires (20) twisted to at least one multifilament textile yarn (30), wherein the plurality of monofilament textile wires (20) are wound onto the at least one multifilament textile yarn (30) and the at least one multifilament textile yarn (30) is also wound onto the plurality of monofilament textile wires (20), wherein each hybrid reinforcement cord (10) includes a number of between 2 and 10 monofilament textile wires (20), wherein, in any cross section of the hybrid reinforcement cord (10), at least one monofilament textile wire ( At least a portion of the at least one multifilament textile yarn (30) defines a first radially outer surface portion of the hybrid reinforcing cord (10), and at least a portion of the at least one multifilament textile yarn (30) defines a second radially outer surface portion of the hybrid reinforcing cord (10), wherein the plurality of monofilament textile wires (20) are twisted together at a predetermined first twist pitch (P1) to form strands of the monofilament textile wire, and the at least one multifilament textile yarn (30) is twisted together with the strands of the monofilament textile wire at a predetermined second twist pitch (P2), wherein each monofilament textile wire (20) of the plurality of monofilament textile wires (20) is made of aliphatic polyamide fiber, polyester fiber, polyaryletherketone fiber or a mixture thereof.

2. The tire (100) according to claim 1, wherein The first radially outer surface portion is defined by at least a portion of at least two monofilament textile wires of the plurality of monofilament textile wires (20).

3. The tire (100) according to claim 1, wherein The at least one multifilament textile yarn (30) comprises textile filaments made from aromatic polyamide fibers, aliphatic polyamide fibers, polyester fibers, polyketone fibers, polyvinyl alcohol fibers, cellulose fibers, glass fibers, carbon fibers, or mixtures thereof.

4. The tire (100) according to claim 1, wherein Each monofilament textile wire (20) of the plurality of monofilament textile wires (20) has a diameter between 0.1 mm and 1 mm.

5. The tire (100) according to claim 1, wherein The at least one multifilament textile yarn (30) has a linear density between 400 dTex and 4500 dTex.

6. The tire (100) according to claim 1, wherein The hybrid reinforcing cord (10) comprises a number of multifilament textile yarns (30) ranging from 1 to 4.

7. The tire (100) according to claim 1, wherein At least some of the hybrid reinforcement cords (10) include at least one metal wire (50) helically wound around the plurality of monofilament textile wires (20) and the at least one multifilament textile yarn (30).

8. The tire (100) according to claim 1, wherein The at least one multifilament textile yarn (30) comprises at least one textile monofilament and a plurality of textile filaments, wherein in any cross section of the hybrid reinforcement cord (10), the at least one textile monofilament is at least partially bonded between the textile filaments.

9. The tire (100) according to claim 1, wherein The support structure (100a) comprises: - a carcass structure (101) comprising at least one carcass ply (111) having opposite end edges (101a) associated with respective annular anchoring structures (102) so as to define respective bead structures (103) on opposite sides relative to the equatorial plane (MM) of the tyre (100); - a belt structure (106) arranged in a radially external position with respect to said carcass structure (101) and in a radially internal position with respect to said tread band (109); Wherein, the hybrid reinforcement cord (10) is arranged in at least one of the following: - the carcass structure (101); - the belt structure (106); - at least one reinforcing layer (120, 121) associated with said at least one carcass layer (111) at or near a respective end edge (101a).

10. The tire (100) according to claim 9, wherein Said belt structure (106) comprises a zero-degrees reinforcement layer (106c) arranged in a radially inner position relative to said tread band (109), wherein said zero-degrees reinforcement layer (106c) comprises a plurality of said hybrid reinforcement cords (10).

11. A hybrid reinforcement cord (10), comprising a plurality of monofilament textile wires (20) and at least one multifilament textile yarn (30) twisted to the plurality of monofilament textile wires (20), wherein: The plurality of monofilament textile wires (20) are wound onto the at least one multifilament textile yarn (30) and the at least one multifilament textile yarn (30) is also wound onto the plurality of monofilament textile wires (20), wherein each hybrid reinforcement cord (10) includes between 2 and 10 monofilament textile wires (20), wherein, in any cross-section of the hybrid reinforcement cord (10), at least a portion of at least one monofilament textile wire (20) of the plurality of monofilament textile wires (20) defines a first radially outer surface portion of the hybrid reinforcement cord (10), and At least a portion of at least one multifilament textile yarn (30) defines a second radially outer surface portion of the hybrid reinforcing cord (10), wherein the plurality of monofilament textile wires (20) are twisted together at a predetermined first twist pitch (P1) to form strands of monofilament textile wires, and the at least one multifilament textile yarn (30) is twisted together with the strands of monofilament textile wires at a predetermined second twist pitch (P2), wherein each monofilament textile wire (20) of the plurality of monofilament textile wires (20) is made of aliphatic polyamide fiber, polyester fiber, polyaryletherketone fiber, or a mixture thereof.

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