RU2806467C2 - Hybrid cord and tire with such cord - Google Patents

Abstract

FIELD: transport vehicles.

SUBSTANCE: tire contains a support structure and a tread band located in a radially outer location relative to the support structure. The support structure contains a plurality of hybrid reinforcing cords (10), each of which has a plurality of monofilament textile threads (20) twisted with at least one multifilament textile thread (30). In any cross section of the hybrid reinforcing cord (10), at least one portion of at least one monofilament textile yarn (20) of said plurality of monofilament textile yarns (20) forms a first portion of the radially outer surface of the hybrid reinforcing cord (10) and at least one portion of said at least one multifilament textile thread (30) forms a second portion of the radially outer surface of the hybrid reinforcing cord (10).

EFFECT: improvement of the operational characteristics.

16 cl, 6 dwg

Description

The present invention relates to a tire for vehicle wheels.

The tire according to the invention is preferably a tire for sports car wheels, in particular high and ultra-high performance cars.

High and ultra-high performance vehicle tires, commonly referred to as “HP” or “UHP” tires, are specifically tires that provide the ability to achieve speeds in excess of 200 km/h, up to and above 300 km/h. Examples of such tires are tires belonging to classes “T”, “U”, “H”, “V”, “Z”, “W”, “Y” according to the E.T.R.T.O. standard. (European Technical Organization for Tires and Rims), and racing tires, in particular for large-displacement four-wheelers. Typically, tires belonging to such classes have a section width equal to or greater than 185 mm, preferably in the range between 195 mm and 385 mm, more preferably in the range between 195 mm and 355 mm. Such tires are typically mounted on rims having seat diameters equal to or greater than 13 inches, preferably not exceeding 24 inches, more preferably ranging between 16 inches and 23 inches.

However, the tire of the invention can be used in vehicles other than the above-mentioned automobiles, such as high performance sports motorcycles.

The tire of the invention contains hybrid reinforcing cords as defined hereinafter.

State of the art

Tires with reinforcing cords containing textile continuous fibers of different materials twisted together are described, for example, in US 7222481 B2, EP 3196343 A1, US 4343343 A1, EP 329590 A1.

The essence of the invention

Throughout the present description and in the following claims, when certain values of certain angles are mentioned, absolute values are meant, that is, either positive values or negative values, relative to the direction or plane of reference, unless otherwise indicated.

In addition, when any range of values between the minimum value and the maximum value is mentioned, it is provided that the aforementioned minimum and maximum values are included in the above range unless expressly stated otherwise.

In what follows, the following definitions apply.

The term "equatorial plane" of a tire is used to refer to the plane that is perpendicular to the axis of rotation of the tire and which divides the tire into two symmetrical equal parts.

The terms "radial" and "axial" and the expressions "radially inner/outer" and "axially inner/outer" are used to refer respectively to a direction substantially parallel to the equatorial plane of the tire and a direction substantially perpendicular to the equatorial plane of the tire, then is with respect to, respectively, 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.

The terms "circumferential" and "along/circumference" are used with respect to the direction of the tire's circumferential extent, that is, the rolling direction of the tire, which corresponds to a direction "lying" in a plane coinciding with the equatorial plane of the tire or substantially parallel to the equatorial plane of the tire.

The term "substantially axial direction" is used to mean a direction inclined relative to the equatorial plane of the tire at an angle ranging between about 70° and about 90°.

The term “substantially circumferential direction” is used to mean a direction oriented relative to the equatorial plane of the tire at an angle ranging between about 0° and about 10°.

The term "elastomeric material" or "elastomer" is used to denote a material containing a natural or synthetic polymer that can be vulcanized and an active filler, such material at indoor temperature and after vulcanization may exhibit force-induced deformation and capable of quickly and completely restoring substantially its original shape and size upon removal of the deforming force (as defined by ASTM D1566-11 Standard Rubber Terminology).

The expression "reinforcing cord", or more simply "cord", is used to designate an element consisting of one or more elongated elements (also called "wires" or "threads"), possibly coated with or embedded in a matrix of elastomeric material.

In the following, the term "wire/monofilament thread" will be used to refer to a single elongated element consisting of a single textile continuous fiber (in this case the expression "monofilament textile thread" or even metallic material will also be used, while the term "multifilament "thread" will be used to refer to an elongated element consisting of a cluster of multiple textile continuous fibers (in this case the expression "multi-filament textile thread" will also be used).

Each continuous fiber may also be referred to simply as a "fiber".

Multifilament filaments may have one or more "strands", with the term "strand" being used to refer to a bundle of continuous fibers twisted together. Preferably there is/are one thread or at least two threads twisted together.

Textile reinforcing cords may be identified by a symbol that represents the textile material, the fiber number used, and the number of threads making up the reinforcing cord. For example, the designation Ar1672 for aramid (aromatic polyamide) strand reinforcement cord indicates a cord containing 1670 dtex aramid fibers and formed from two strands twisted together.

The term "strand" is used to mean an assembly of at least two monofilament strands or multifilament strands, or at least one monofilament strand and at least one multifilament strand, to form an elongate member for being twisted together with at least one other elongate member. for forming at least one part of the reinforcing cord.

The expression “hybrid reinforcing cord” is used to refer to a reinforcing cord comprising at least one monofilament textile yarn and at least one multifilament textile yarn, wherein the monofilament yarn and the multifilament textile yarn are formed from the same textile material or from different textile materials.

The expression "non-hybrid reinforcing cord", especially when applied to textile reinforcing cords, is used to designate a reinforcing cord containing only monofilament textile yarns or only multifilament textile yarns.

The term "diameter" of a reinforcing cord or monofilament yarn or multifilament yarn is used to refer to the diameter measured as prescribed by BISFA Method E10 (Bureau International Standards for Man-made Fibers, Internationally Harmonized Test Methods for Steel Tire Cords, 1995 Edition).

In the case of multifilament yarns, the term "diameter" is used to refer to the diameter of the ideal circle that describes all the continuous fibers that make up the multifilament yarn.

The term "density" of a layer is used to indicate the number of reinforcing cords that are provided in such a layer per unit length. Density can be measured in cords per dm (cords per decimeter).

The term "linear density" or "number" of a cord or monofilament yarn/multifilament yarn is used to indicate the mass of the cord or monofilament yarn/multifilament yarn per unit length. Linear density can be measured in dtex (grams per 10 km length). For determination of linear density, reference should be made to straight monofilament/multifilament yarns without twists applied during the testing phase or during the twisting phase, as per BISFA regulated tests. For example, it should be mentioned:

for aramid fibers (AR):

- Test methods for para-aramid fiber yarns, 2002 edition.

-- Determination of linear density - Chapter 6

-- Determination of tensile mechanical properties - Chapter 7 - Test procedure - Clause 7.5 - in the procedure with initial pretension;

for lyocell fibers:

-- Determination of linear density - Chapter 6

-- Test Methods for Viscose, Copper-Ammonia, Acetate, Triacetate Continuous and Lyocell Yarns - 2007 Edition, Determination of Tensile Mechanical Properties - Chapter 7 - Tensile Test Conditions: Oven Drying Test - Table 7.1 - Test procedure - Clause 7.5 - When testing with oven drying for samples subjected to relaxation - Subclause 7.5.2.4.

Sports car tires must have high traction to ensure that the high torque they are subjected to is effectively transferred to the ground, thereby achieving high traction and effective braking power. Such tires must also be lightweight and provide adequate response to the lateral loads to which the tire is subjected during cornering.

Sports car tires typically comprise a radial carcass structure extending between opposing bead structures, a cross-cord belt structure located at a radially outer location relative to the carcass structure, a reinforcement layer having cords positioned at an angle of zero degrees, and a in a radially outer location relative to the belt structure with intersecting cords, and a tread band located in a radially outer location relative to the reinforcing layer with cords located at an angle of zero degrees.

The carcass structure is designed to provide the tire with specified integrity and structural strength characteristics, while the belt structure, in addition to helping to provide the aforementioned integrity and structural strength characteristics, is designed to transfer the lateral and longitudinal loads to which the tire is subjected while driving in contact with the surface. road, - a frame structure to give the tire specified performance characteristics (that is, traction, driving stability, controllability, directionality, road holding) and provide comfort. On the other hand, a reinforcing layer with cords angled at zero degrees is designed to limit the radial deformation of the belt structure.

For these reasons, one or more reinforcing layers are provided in the frame structure and in the belt structure, each reinforcing layer comprising a plurality of reinforcing cords having a proper slope relative to the circumferential or rolling direction, while the reinforcing cords are oriented substantially parallel to the rolling direction. along the circumference or rolling direction, are provided in a reinforcing layer with cords located at an angle of zero degrees.

In connection with the general trend towards reducing CO ₂ emissions into the atmosphere, the Applicant considered the problem of reducing the rolling resistance of the tires it produces, including tires for sports cars.

Thus, the Applicant considered it appropriate to use reinforcing cords that are as light as possible in the sports car tires it produces.

For some time the Applicant has been producing and selling tires containing particularly lightweight reinforcing cords made of metallic material. Each of these reinforcing cords contains 3 steel wires twisted together, each steel wire having a diameter of 0.175 mm.

The applicant focused on textile reinforcing cords.

The Applicant has found through observation that even based only on the type of elongated elements used in the reinforcing cord (monofilament textile yarns, multifilament textile yarns and/or a possible combination of one or more of the above-mentioned monofilament yarns with one or more of the above-mentioned multifilament yarns), a variety of hybrid reinforcing cords having characteristics theoretically suitable for use in a carcass structure and/or a belt structure and/or a zero degree cord reinforcement layer in sports car tires.

In particular, the Applicant has established through observation that, given the same material and diameter, monofilament textile yarns are better suited than multifilament textile yarns to withstand compressive and bending loads and to reduce the hysteresis caused by friction between monofilament yarns and/or textile continuous fibers , while multifilament textile yarns are more suitable than monofilament textile yarns for withstanding tensile loads and for adhesively bonding to the surrounding elastomeric material.

However, the Applicant also took into account that in tires for any type of vehicle it is necessary to ensure good adhesive bond between the reinforcing cords and the surrounding elastomeric material. This leads to the use of reinforcing cords containing multifilament textile yarns in tires, thereby also providing good resistance to the tensile stresses to which reinforcing cords are typically subjected.

The Applicant also took into account that in order to reduce the problems associated with hysteresis, as well as to provide the above-mentioned reinforcing cords with a specified resistance to the compressive and bending loads to which the reinforcing cords are typically subjected, monofilament textile yarns are more suitable, as indicated above .

The Applicant has found that the above conflicting requirements can be satisfied by forming a hybrid reinforcing cord containing more than one monofilament textile yarn, and twisting the monofilament textile yarns together with at least one multifilament textile yarn so that at least one portion of the radially outer surface of the hybrid reinforcing yarn the cord was formed by at least one of the monofilament textile yarns and at least one other portion of the radially outer surface of the hybrid reinforcing cord was formed by the at least one multifilament textile yarn.

Therefore, in accordance with its first aspect, the present invention relates to a tire for vehicle wheels comprising a support structure and a tread band located at a radially outer location relative to the support structure.

The support structure preferably comprises a plurality of hybrid reinforcing cords.

Each of said hybrid reinforcing cords preferably comprises a plurality of monofilament textile yarns spun with at least one multifilament textile yarn.

Preferably, in any cross section of the hybrid reinforcing cord, at least one monofilament textile yarn portion of said plurality of monofilament textile yarns forms a first portion of the radially outer surface of the hybrid reinforcing cord.

Preferably, in any cross section of the hybrid reinforcing cord, at least one portion of said at least one multifilament textile yarn forms a second portion of the radially outer surface of the hybrid reinforcing cord.

The Applicant has found that the presence of a plurality of monofilament textile yarns in the hybrid reinforcing cord of the invention makes it possible to provide a given resistance to compressive and bending loads/stresses and a given reduction in hysteresis, while the presence of at least one multifilament textile yarn makes it possible to provide a given tensile strength . In addition, the fact that the monofilament textile threads and the multifilament textile thread are mutually positioned such that the outer surface of the reinforcing cord is formed by both a part of the at least one multifilament textile thread and a part of the at least one monofilament textile thread makes it possible to achieve desired results in terms of adhesive bonding to the surrounding elastomeric material and reduction of hysteresis.

In addition, twisting the monofilament textile yarns together with the at least one multifilament textile yarn provides a hybrid reinforcing cord with good fatigue properties.

In accordance with its second aspect, the invention relates to a hybrid reinforcing cord.

The hybrid reinforcing cord preferably comprises a plurality of monofilament textile yarns and at least one multifilament textile yarn twisted with said plurality of monofilament textile yarns.

Preferably, in any cross section of the hybrid reinforcing cord, at least one portion of a monofilament textile yarn from said plurality of monofilament textile yarns forms a first portion of the radially outer surface of the hybrid reinforcement cord and at least one portion of said at least one multifilament textile yarn forms a second portion of the radially outer surface surface of the hybrid reinforcing cord.

The Applicant believes that the above-described hybrid reinforcing cords can be used in tires of all types of vehicles that require high performance, therefore not only in sports cars, but also, for example, in sports motorcycles, thereby providing the advantages discussed higher.

As discussed further, Applicant also believes that the above-described hybrid reinforcing cords can be used in a carcass structure as well as a tire belt structure or only a tire belt structure, as well as a reinforcing layer with cords angled at zero degrees, or only in this layer.

Applicant also believes that the above-described hybrid reinforcing cords can be used also or only in other tire reinforcing components, such as, for example, the tire reinforcing components described below and referred to as "fender tape" and "bead tape", instead of conventional metal cords ( with the associated benefits of reduced tire weight and the ability to run flat without risk of overheating of the reinforcing cords) and instead of conventional textile cords containing only multifilament textile yarns (with associated benefits of stiffness, fatigue resistance and performance).

In addition, the use of the above-described hybrid reinforcing cords in the tire belt structure can reduce or completely eliminate the occurrence of undesirable effects on possible radio frequency identification (RFID) processes of the tire and/or on signals transmitted by possible sensors located inside the tire, such as, for example, pressure sensors and /or temperature sensors.

In accordance with at least one of the above aspects, the present invention may have at least one of the preferred features described below.

Said first radially outer surface portion is preferably formed by at least one portion of at least two of said monofilament textile yarns, wherein in this case one or more monofilament textile yarns are completely surrounded by continuous fibers of the multifilament textile yarn and at least two monofilament textile threads.

However, alternative embodiments are possible in which said first radially outer surface portion is formed by at least one portion of each of the monofilament textile yarns of said plurality of monofilament textile yarns.

In a specific embodiment, approximately 50% of the outer surface of the hybrid reinforcing cord is formed by said at least one portion of at least one multifilament textile yarn and approximately 50% of the outer surface of the hybrid reinforcing cord is formed by said at least one portion of at least one of said monofilament yarns. textile threads. This means that, relative to the theoretical center of the reinforcing cord, the angular extent of said first radially outer surface portion is substantially equal to the angular extent of said second radially outer surface portion.

However, the angular extent of said first radially outer surface portion may be greater or less than the angular extent of said second radially outer surface portion, wherein the aspect ratio in the first case promotes adhesive bonding to the detriment of hysteresis-related characteristics, and in the second case improves the hysteresis-related characteristics. with hysteresis, to the detriment of adhesive bonding.

In first embodiments, said plurality of monofilament textile yarns are twisted together with a predetermined first twisting step to form a strand of monofilament textile yarns.

Said at least one multifilament textile thread is preferably twisted together with said strand of monofilament textile yarns at a predetermined second twist pitch.

In second embodiments, at least one first monofilament textile yarn of said plurality of monofilament textile yarns is twisted together with said at least one multifilament textile yarn at a predetermined first twist pitch to form a strand of mono- and multifilament textile yarns.

The above twist pitch is preferably greater than or equal to about 2 mm, more preferably greater than or equal to about 3 mm.

The above twist pitch is preferably less than or equal to about 20 mm, more preferably less than or equal to about 10 mm.

In preferred embodiments, the above twist pitch is in the range between about 2 mm and about 20 mm, preferably between about 3 mm and about 10 mm.

At least one second monofilament textile thread from said plurality of monofilament textile threads is preferably twisted together with said strand of mono- and multifilament textile threads at a predetermined second twist pitch.

In both of the above embodiments, the first twist step may be equal to the second twist step or may be different from the second twist step.

In some preferred embodiments, the first twist step is different from (more or less than) the second twist step.

In further embodiments, each monofilament textile thread of said plurality of monofilament textile threads is twisted together with at least one other monofilament textile thread of said plurality of monofilament textile threads and with said at least one multifilament textile thread at a predetermined twist pitch to form a strand of mono - and multifilament textile threads.

This twisting step is preferably equal to the above-mentioned first twisting step.

In all embodiments, each monofilament textile yarn of said plurality of monofilament textile yarns is preferably formed from 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), polyarylether ketone fibers (e.g. polyether ether ketone) or mixtures thereof.

In all embodiments, said at least one multifilament textile yarn preferably comprises continuous fibers formed from 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, cellulose fibers (e.g., hydrated cellulose fibers, lyocell fibers), glass fibers, carbon fibers, or their mixtures.

Each monofilament textile thread of the plurality of monofilament textile threads preferably has a diameter that is greater than or equal to about 0.1 mm, more preferably greater than or equal to about 0.2 mm.

Said diameter is preferably less than or equal to approximately 1 mm, more preferably less than or equal to approximately 0.5 mm.

In preferred embodiments, said diameter is in the range between about 0.1 mm and about 1 mm, preferably between about 0.2 mm and about 0.5 mm.

Said hybrid reinforcing cord preferably contains monofilament textile yarns in an amount greater than or equal to 2.

The above number of monofilament textile yarns is preferably less than 10, more preferably less than or equal to 8, even more preferably less than or equal to 6.

In preferred embodiments, said number of monofilament textile yarns is in the range between 2 and 10, more preferably between 2 and 8, even more preferably between 2 and 6, for example 3 or 4.

In general, it is preferably provided that the more monofilament textile threads are contained in the hybrid reinforcing cord, the smaller the diameter of said monofilament textile threads.

Said at least one multifilament textile yarn preferably has a linear density that is greater than or equal to about 400 dtex, more preferably greater than or equal to about 800 dtex.

Said linear density is preferably less than or equal to about 4500 dtex, more preferably less than or equal to about 4000 dtex.

In preferred embodiments, said linear density is in the range between about 400 dtex and about 4500 dtex, preferably between about 800 dtex and about 4000 dtex.

Said hybrid reinforcing cord preferably contains multifilament textile yarns in an amount greater than or equal to 1.

The number of multifilament textile threads is preferably less than or equal to 4, more preferably less than or equal to 3, even more preferably less than or equal to 2.

The number of multifilament textile threads is preferably in the range between 1 and 4, more preferably between 1 and 3, even more preferably between 1 and 2, for example equal to 1.

In some embodiments, at least some of said hybrid reinforcing cords comprise at least one metal wire wound helically around said plurality of monofilament textile yarns and the at least one multifilament textile yarn.

The above-mentioned metal wire preferably helps to increase the strength of the reinforcing cord and keep the monofilament textile yarns firmly twisted with the multifilament textile yarn.

The direction of winding of the metal wire on the assembly formed by the monofilament textile threads and the at least one multifilament textile thread may or may not be related to the direction of twist of the monofilament textile threads relative to the at least one multifilament textile thread.

The above-mentioned winding direction is preferably opposite to the above-mentioned twisting direction.

The metal wire is preferably wound on the above set with a winding pitch greater than about 2 mm, more preferably greater than about 3.5 mm.

The metal wire is preferably wound on the above set with a winding pitch of less than about 10 mm, more preferably less than about 5 mm.

In preferred embodiments, the metal wire is wound on the above assembly with a winding pitch ranging between about 2 mm and about 10 mm, preferably between about 3.5 mm and about 5 mm.

Said metal wire preferably has a diameter greater than about 0.08 mm, more preferably greater than about 0.10 mm.

Said metal wire preferably has a diameter of less than about 0.20 mm, more preferably less than about 0.15 mm.

Said metal wire preferably has a diameter in the range between about 0.08 mm and about 0.20 mm, more preferably between about 0.10 mm and about 0.15 mm.

Hybrid reinforcing cords containing the above-mentioned metal wires are preferably used in cross-cord belt structures and/or in a zero-degree belt ply and/or in the above-mentioned stiffening layers.

The continuous fibers of said at least one multifilament textile yarn are preferably coated with an adhesive or chemically or physically treated to impart adhesive properties to further improve adhesive bonding to the elastomeric material in which they are embedded or coated.

In some embodiments, said at least one multifilament textile yarn comprises at least one textile monofilament fiber and a plurality of textile continuous fibers.

In this case, in any cross section of the hybrid reinforcing cord, said at least one textile monofilament is at least partially located between said textile continuous fibers, for example, partially or completely surrounded by said textile continuous fibers.

Each monofilament textile thread can be twisted around itself with a given first pitch of twist. The Applicant has determined through observation that such a measure can help optimize the fatigue performance of the reinforcing cord.

Said first twist pitch is preferably equal to said twist pitch. In this way, the "envelopment" of the monofilament textile yarns by the continuous fibers of the corresponding multifilament textile yarns is maximized, which greatly contributes to the adhesive bond of the hybrid reinforcing cord to the surrounding elastomeric material.

Said at least one multifilament textile thread may or may not be twisted around itself with a predetermined second twist pitch. When it is twisted around itself, the second twist pitch is preferably equal to said twist pitch. This is intended to maximize the "coverage" of the monofilament textile yarns over the continuous fibers of the multifilament textile yarn.

Said support structure preferably comprises a carcass structure comprising at least one carcass ply having opposite end edges coupled to respective annular locking structures (e.g., folded around respective annular locking structures) to form respective bead structures on sides opposite relative to the equatorial plane of the tire .

Said support structure preferably comprises a cross-cord belt structure located at a radially outer location relative to the carcass structure and at a radially inboard location relative to the tread band.

Said plurality of hybrid reinforcing cords are preferably located in said frame structure and/or in said belt structure.

The support structure may also comprise, as an alternative to or in addition to the cross-cord belt structure, a reinforcing layer which has cords positioned at a zero degree angle and which may comprise non-hybrid reinforcing cords which preferably comprise only monofilament textile yarns or multifilament textile yarns , formed, for example, from aramid, nylon, or hybrid reinforcing cords of the above type.

Said support structure preferably comprises at least one stiffening layer connected to said at least one carcass layer adjacent to or adjacent to a corresponding end edge, and said plurality of hybrid reinforcing cords are disposed in said at least one stiffening layer. rigidity.

Said at least one stiffening layer may preferably be connected to said at least one frame layer adjacent to or adjacent to a corresponding side structure.

Said at least one stiffening layer may preferably be located between the corresponding end edge of said at least one frame layer and the corresponding side structure.

More preferably, said at least one stiffening layer may at least partially surround said side structure. This stiffening layer is also called “wing tape”.

Alternatively or in addition, said at least one stiffening layer may be connected to a corresponding end edge of said at least one frame layer at a location axially outer with respect to the corresponding annular fixing structure.

More preferably, said at least one stiffening layer may extend from said annular retaining structure towards said tread band. This stiffening layer is also called "bead tape".

The bead strip may be located at an axially outer location or at an axially inner location relative to the end edge of the at least one carcass ply. In the case where the frame structure contains multiple frame layers, for example two, the bead strip may be located between the respective end edges of the different frame layers.

In preferred embodiments of tires in which said plurality of hybrid reinforcing cords are arranged in a carcass structure, each of said hybrid reinforcing cords comprises three monofilament textile yarns which are formed from nylon and each having a diameter of approximately 0.21 mm, and a multifilament a textile thread formed from nylon and having a linear density of approximately 1400 dtex. This tire is particularly suitable for use in high and ultra high performance vehicles as defined above.

In preferred embodiments of tires in which said plurality of hybrid reinforcing cords are arranged in a cross-cord belt structure, each of said hybrid reinforcing cords comprises three monofilament textile yarns that are formed from polyethylene terephthalate (PET) and each of which has a diameter of approximately 0 .40 mm, and a multifilament textile thread formed from aramid and having a linear density of approximately 1100 dtex. This tire is particularly suitable for use in high and ultra high performance vehicles as defined above.

In preferred embodiments of tires in which said plurality of hybrid reinforcing cords are arranged in a belt ply with the cords positioned at an angle of zero degrees, each of said hybrid reinforcing cords comprises two strands twisted together, each of which contains two monofilament textile threads which are formed from polyethylene terephthalate (PET) and each of which has a diameter equal to approximately 0.20 mm, and a multifilament textile thread formed from aramid, twisted with the above two strands and having a linear density equal to approximately 1100 dtex. This tire is also particularly suitable for use in high and ultra high performance vehicles as defined above.

In preferred embodiments of tires in which said plurality of hybrid reinforcing cords are located in said at least one stiffening layer, for example, a bead tape or a wing tape, the hybrid reinforcing cords are identical to those described above as being used in a belt structure with intersecting cords.

Brief description of drawings

Additional characteristics and advantages of the tire of the present invention will become more apparent from the following detailed description of preferred embodiments thereof, taken in conjunction with the accompanying drawings. On the drawings:

FIG. 1 is a schematic view of a partial half-section of a part of a tire according to an embodiment of the present invention; FIG.

FIG. 2 is a schematic side view of a portion of the hybrid reinforcing cord of the first embodiment used in the tire of FIG. 1;

FIG. 3 is a schematic enlarged view of the cross-section of the hybrid reinforcing cord of FIG. 2, such cross-section being in the section plane S-S shown in FIG. 2;

FIG. 4 is a schematic side view of a portion of the hybrid reinforcing cord of the second embodiment used in the tire of FIG. 1; FIG.

FIG. 5 is a schematic enlarged view of the cross-section of the hybrid reinforcing cord of FIG. 4, such cross-section being in the section plane S-S shown in FIG. 4; And

Fig.6 is a schematic side view of a section of the hybrid reinforcing cord along the third embodiment used in the bus of FIG. 1.

Description of Embodiments of the Invention

For simplicity, FIG. 1 shows only a portion of an embodiment of a tire 100 in accordance with the present invention, with the remaining portion, which is not shown, being substantially identical and located symmetrically with respect to the equatorial plane M-M of the tire.

The tire 100 shown in FIG. 1 is, in particular, an embodiment of a tire for four-wheeled vehicles.

Tire 100 is preferably a high performance (HP) or ultra high performance (UHP) tire for sports cars and/or high or ultra high performance vehicles.

In FIG. 1, “a” denotes the axial direction, “c” denotes the radial direction, “M-M” denotes the equatorial plane of the tire 100, and “R-R” denotes the rotation axis of the tire 100.

The tire 100 includes at least one support structure 100a and, at a radially outer location relative to the support structure 100a, a tread band 109 of an elastomeric material.

The support structure 100a includes a frame structure 101, which in turn contains at least one frame layer 111.

In the following, for ease of presentation, reference will be made to an embodiment of a tire 100 comprising a single carcass ply 111. However, it should be understood that what is described has similar application in tires containing more than one carcass ply.

The carcass layer 111 has end edges opposed in the axial direction and in contact with corresponding annular retaining structures 102, called bead cores, optionally connected to an elastomeric filler 104. The region of the tire 100 containing the bead core 102 and optional elastomeric filler 104 forms an annular reinforcement a structure 103, referred to as a "bead structure" and designed to enable the tire 100 to be supported/fixed on a corresponding mounting rim, not shown.

The carcass layer 111 comprises a plurality of reinforcing cords 10' coated with an elastomeric material or embedded in a matrix of cross-linked elastomeric material.

The carcass structure 101 is a radial type structure, that is, the reinforcing cords 10' are located in planes containing the axis R-R of rotation of the tire 100 and substantially perpendicular to the equatorial plane M-M of the tire 100.

Each annular reinforcement structure 103 is connected to the carcass structure 101 by folding (or folding) opposite end edges of the at least one carcass layer 111 around the bead core 102 and optional elastomeric filler 104 to form so-called flaps 101a of the carcass structure 101.

In an embodiment, the connection between the frame structure 101 and the annular reinforcement structure 103 may be made by a second frame layer (not shown in FIG. 1) applied at a radially outer location relative to the frame layer 111.

An anti-abrasion tape 105 is located in the area of each ring reinforcement structure 103 to surround the ring reinforcement structure 103 along the axially inner, axially outer and radially inner zones of the ring reinforcement structure 103, thus the tape 105 will be located between the ring reinforcement structure 103 and the wheel rim when the tire 100 is mounted on the rim. However, such anti-abrasion tape 105 may not be provided.

The support structure 100a includes, at a radially outer location relative to the carcass structure 101, a cross-cord belt structure 106 comprising at least two belt layers 106a, 106b superimposed on each other in the radial direction.

The belt layers 106a, 106b respectively comprise a plurality of reinforcing cords 10a, 10b. Such reinforcing cords 10a, 10b have an orientation inclined relative to the circumferential direction of the tire 100 or relative to the equatorial plane M-M of the tire 100 at an angle ranging between about 15° and about 45°, preferably between about 20° and about 40°. For example, such an angle is approximately 30°.

The reinforcing cords 10a, 10b of the belt layer 106a, 106b are parallel to each other and have a crisscross orientation relative to the reinforcing cords of the other belt layer 106b, 106a.

In ultra-high performance tires, the belt structure 106 may be a cross-corded belt structure with a turn-over. Such a belt structure is formed by placing at least one belt layer on a support element and folding opposite side end edges of the at least one belt layer. Preferably, first the first belt layer is placed on the support element, then the support element is moved apart in the radial direction, then the second belt layer is placed on the first belt layer, and finally the axially opposite end edges of the first belt layer are folded over the second belt layer for at least as partial closure of the second belt layer, which is the layer furthest from the center in the radial direction. In some cases, a third belt layer may be placed on the second belt layer. Folding the axially opposite end edges of a belt ply over another belt ply located at a radially outer location advantageously provides the tire with greater cornering responsiveness and sensitivity.

The support structure 100a includes, at a radially outer location relative to the criss-cross cord breaker structure 106, at least one reinforcing layer 106c having cords at a zero degree angle, commonly known as a “zero degree cord breaker.” " It contains reinforcing cords 10c oriented substantially in the circumferential direction. Thus, such reinforcing cords 10c form an angle of several degrees with respect to the equatorial plane M-M of the tire 100.

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

The tread band 109 is made of an elastomeric material like other semi-finished products forming the tire 100, and is superimposed at a radially outer location with respect to the reinforcing layer 106c with cords positioned at an angle of zero degrees.

Corresponding sidewalls 108 made of an elastomeric material are also applied to the side surfaces of the frame structure 101 at a location axially outer with respect to the frame structure 101 itself. Each sidewall 108 extends from one of the side edges of the tread band 109 to a corresponding ring reinforcement structure 103.

The anti-abrasion tape 105, if provided, extends at least as far as the corresponding sidewall 108.

In some specific embodiments, like the embodiment shown and described herein, the rigidity of the sidewall 108 may be increased by providing a stiffening layer 120, which is commonly known as a "wing tape" or additional tape-like insert, and which is designed to enhance rigidity and integrity. ring strengthening structure 103 and sidewall 108.

The wing tape 120 is wound around a respective bead core 102 and the elastomeric filler 104 so that it at least partially surrounds the annular reinforcement structure 103. Specifically, the wing tape 120 surrounds the annular reinforcement structure 103 along the axially inner, axially outer and radially inner zones of the annular reinforcement designs 103.

The wing strip 120 is located between the folded end edge of the carcass layer 111 and the corresponding annular reinforcement structure 103. The wing strip 120 is generally in contact with the carcass layer 111 and the annular reinforcement structure 103.

In some specific embodiments, similar to the embodiment shown and described herein, the bead structure 103 may also include an additional stiffening layer 121, which is commonly known as bead tape or protective strip, and which is designed to increase rigidity and integrity of the ring reinforcing structure 103.

The bead strip 121 is connected to the corresponding folded end edge of the carcass ply 111 at a location axially outer of the corresponding annular reinforcement structure 103 and extends radially toward the sidewall 108 and the tread band 109.

The wing tape 120 and the bead tape 121 comprise reinforcing cords 10d (the reinforcing cords of the wing tape 120 are not visible in the accompanying figures) coated with an elastomeric material or embedded in a matrix of cross-linked elastomeric material.

The tread band 109 has at its radially outer location a rolling surface 109a for contacting the ground. The rolling surface 109a has circumferential grooves (not shown in FIG. 1) formed thereon, which grooves are connected by transverse grooves (not shown in FIG. 1) to form a plurality of blocks of different shapes and sizes (not shown in FIG. 1) on the rolling surface 109a. Fig.1).

The sublayer 107 is located between the cross-cord belt structure 106 and the tread band 109.

In some specific embodiments, similar to the embodiment shown and described herein, a strip 110 consisting of an elastomeric material, commonly known as a "minisidewall", may be provided in the junction area between the sidewalls 108 and the tread band 109, if desired. The minisidewall 110, typically extruded together with the tread band 109, and the minisidewall 110 allows for improved mechanical interaction between the tread band 109 and the sidewalls 108.

The end portion of the sidewall 108 preferably directly covers the side edge of the tread band 109.

In the case of tubeless tires, a rubber layer 112, commonly known as a “sealing layer,” may also be provided at a radially internal location relative to the carcass layer 111 to provide the necessary impermeability to the air with which the tire 100 is inflated.

At least some of the reinforcing cords 10' (preferably all the reinforcing cords 10' provided in the carcass layer 111) and/or 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 a cross-cord and turn-over belt structure) and/or reinforcing cords 10c of the reinforcing layer 106c with cords positioned at an angle of zero degrees, and/or reinforcing cords 10d of the wing tape 120 and/or the side tape 121 are hybrid reinforcing cords 10 of the type shown in FIGS. 2-6 and described below.

As shown in FIGS. 2 and 3, the hybrid reinforcing cord 10 comprises three monofilament textile yarns 20 twisted together and a multifilament textile yarn 30 twisted with three monofilament textile yarns 20 at a predetermined twist pitch and formed by a plurality of continuous fibers 32.

The three monofilament textile yarns 20 are preferably identical. Therefore, only one of them will be described in the following.

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

The first method involves initially twisting three monofilament textile yarns 20 with a twist pitch P1 to form a strand of monofilament textile yarns 20. The strand is then twisted together with a multifilament textile yarn 30 with a twist pitch P2, which may be equal to or different from the twist pitch P1 twisting step P1.

The second method involves initially twisting one or more monofilament textile threads 20 together with a multifilament textile thread 30 at a twist pitch P1 to form a strand of mono- and multifilament textile threads. Thereafter, such a strand is twisted together with another monofilament textile thread 20 with a twist pitch P2, which may be equal to or different from the twist pitch P1.

The third method involves a single twisting operation in which each of the monofilament textile threads 20 is twisted together with the remaining monofilament textile threads 20 and with the multifilament textile thread 30 with a predetermined twist pitch P1 to form a strand of mono- and multifilament textile threads.

In the embodiment shown in FIGS. 2 and 3, each monofilament textile thread 20 in any cross-section of the reinforcing cord 10 (such as, for example, the cross-section of FIG. 3) and preferably in all cross-sections of the reinforcing cord 10 is located outside the relatively continuous fibers. 32 multifilament textile thread 30.

The relative position of the monofilament textile threads 20 and the multifilament textile thread 30 is such that the first portion of the radial outer surface of the hybrid reinforcing cord 10 is formed by a portion of each of the three monofilament textile threads 20 and the second portion of the radial outer surface of the hybrid reinforcing cord 10 is formed by a portion of the multifilament textile thread 30.

For example, approximately 50% of the outer surface of the hybrid reinforcing cord 10 is formed by multifilament textile yarn 30 and the remaining approximately 50% is formed by monofilament textile yarn 20.

In the example shown in FIGS. 2 and 3, each of the three monofilament textile threads 20 is in contact with the other two monofilament textile threads, and only two of the three monofilament textile threads 20 are in contact with the multifilament textile thread 30.

The monofilament textile threads 20 and the multifilament textile threads 30 extend along the longitudinal direction A shown in FIG. 2.

The twist pitch P1 is preferably between about 2 mm and about 20 mm, more preferably between about 3 mm and about 10 mm, for example about 3.5 mm.

Each monofilament textile yarn 20 is formed from fibers made from an aliphatic polyamide, for example, 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, for example, polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polyethylene isophthalate (PEI), or polyaryletherketone fibers, such as polyetheretherketone (PEEK), or mixtures thereof.

The continuous fibers 32 of the multifilament textile yarn 30 are formed from aromatic polyamide fibers or from aliphatic polyamide fibers, for example, 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 from polyester fibers, for example polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polyethylene isophthalate (PEI), or from polyketone fibers, or from polyvinyl alcohol fibers, or from cellulosic fibers, for example hydrated cellulose fibers or lyocell fibers, or of glass fibers or carbon fibers, or of any other mixture of the foregoing fibers, or of mixed fiber assemblies containing two or more of the above materials. Such mixed fiber assemblies are hereinafter referred to as "mixed fibers".

In the case of "mixed fibers", the fibers forming the continuous fibers 32 may, for example, contain:

- 50% aramid fibers with a linear density of approximately 1100 dtex, and 50% polyethylene terephthalate (PET) fibers with a linear density of approximately 1100 dtex (this combination is hereinafter referred to as “mixed fibers with a linear density of 2200 dtex”);

- 43% aramid fibers with a linear density of approximately 840 dtex, and 57% polyethylene terephthalate (PET) fibers with a linear density of approximately 1100 dtex (this combination is hereinafter referred to as “mixed fibers with a linear density of 1940 dtex”);

- 33% aramid fibers with a linear density of approximately 550 dtex, and 67% polyethylene terephthalate (PET) fibers with a linear density of approximately 1100 dtex (this combination is hereinafter referred to as “mixed fibers with a linear density of 1650 dtex”).

Regardless of the specific type of textile material used for the continuous fibers 32 of the multifilament textile yarn 30, such material is suitably subjected to surface adhesive processing so that it has the proper ability to adhesively adhere to the surrounding elastomeric material. Generally, imparting adhesive adhesion may be accomplished by coating with an adhesive substance or by chemical or physical treatment.

For example, imparting adhesive adhesion is accomplished by immersing the hybrid reinforcing cord 10 in a solution containing an adhesive agent after twisting the monofilament textile yarns 20 together with the multifilament textile yarn 30.

Each monofilament textile thread 20 preferably has a diameter in the range between about 0.1 mm and about 1 mm, more preferably between about 0.2 mm and about 0.5 mm, which also depends on the material from which it is formed and the area tire 100, in which hybrid reinforcing cords 10 are placed.

The multifilament textile thread 30 preferably has a linear density in the range between about 400 dtex and about 4500 dtex, preferably between about 800 dtex and about 4000 dtex, which also depends on the material from which the multifilament textile thread 30 is formed and the area of the tire 100 in which which contains hybrid reinforcing cords 10.

In specific embodiments, only the reinforcing cords 10', and not the reinforcing cords 10a, 10b, 10c and 10d, or vice versa, are hybrid reinforcing cords 10 of the type described above.

In other specific embodiments, only the reinforcing cords 10a, and not the reinforcing cords 10', 10b, 10c, 10d, or vice versa, are hybrid reinforcing cords 10 of the type described above.

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

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

When the reinforcing cords 10d are hybrid reinforcing cords 10 of the type described above, such hybrid reinforcing cords 10 can only be used in the wing tape 120 (if provided and when the side strip is not provided or is provided and contains non-hybrid reinforcing cords), only in the bead tape 121 (if provided and where the wing tape is not provided or is provided and contains non-hybrid reinforcing cords), or in both the wing tape 120 and the side tape 121 (if both are provided).

4 and 5 show an embodiment of a hybrid reinforcing cord 10 that differs from the embodiment of the previous figures only in that the multifilament textile yarn 30 comprises a monofilament textile yarn 31 sandwiched between continuous fibers 32.

FIG. 6 shows an embodiment of a hybrid reinforcement cord 10 which differs from the embodiment of the previous figures only in that the hybrid reinforcement cord 10 also includes a metal wire 50 wound spirally around monofilament textile yarns 20 twisted together with a multifilament textile yarn 30.

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

The winding of metal wire 50 has a winding pitch preferably in the range 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.

Applicant has produced some examples of hybrid reinforcing cords 10 for the carcass structure 101, for the cross-cord belt structure 106, for the zero degree cord reinforcement layer 106c, and for the stiffening layers 120, 121 of the tire 100 of the present invention.

A hybrid reinforcing cord 10 has been manufactured for use in the carcass structure 101 of a tire 100 of the type shown in FIG. 1, and therefore intended for use in high- and ultra-high-performance vehicles as defined above, and comprising three monofilament textile threads 20, which are formed from nylon, each of which has a diameter equal to approximately 0.21 mm, and which are twisted together with a multifilament textile thread 30, formed from nylon and having a linear density equal to approximately 1400 dtex. This reinforcing cord is briefly designated as: Ny 3×0.21 mm+Ny 1400 dTex.

A hybrid reinforcing cord 10 has been fabricated for use in the cross-ply belt structure 106 of a tire 100 of the type shown in FIG. 1, and therefore intended for use in high- and ultra-high-performance vehicles as defined above, and containing three monofilament textile threads 20, which are formed from polyethylene terephthalate (PET), each of which has a diameter of approximately 0.40 mm, and which are twisted together with a multifilament textile thread 30, formed from aramid and having a linear density of approximately 1100 dtex. This reinforcing cord is briefly designated as: PET 3×0.40 mm+Ar 1100 dTex.

A hybrid reinforcing cord 10 has been fabricated for use in the zero degree belt ply 106c in a tire 100 of the type shown in FIG. 1 and is therefore intended for use in vehicles with high and ultra-high performance as defined above, and comprising two strands, each of which contains two monofilament textile threads 20, which are formed from polyethylene terephthalate (PET) and each of which has a diameter of approximately 0.20 mm, the two strands being twisted together with multifilament textile thread 30 formed from aramid. Multifilament textile thread 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.

The applicant has also manufactured reinforcing cords 10 for the stiffening layer 120 or 121 of the tire 100. Such reinforcing cords 10 are of the same design and made from the same materials as described above with respect to the cross-cord belt structure 106.

Comparative tests

For some of the reinforcing cords 10 described above, the Applicant has performed tests for comparison with known reinforcing cords that are currently in use by the Applicant and are currently considered suitable for providing the desired driving characteristics and desired behavior of the tire. Some of these tests are discussed below.

A test was performed to measure the hysteresis (energy dissipated due to friction between monofilament yarns/continuous fibers) of a 200 mm long piece of Ny 3×0.21 mm+Ny 1400 dTex type hybrid reinforcing cord in comparison with the hysteresis of a 200 mm long piece of a known reinforcing cord made by twisting together two multifilament strands of 1400 dtex nylon (referred to herein as: 2 × Ny 1400 dTex).

The reinforcing cords from which both pieces described above were derived had substantially the same weight and the same volume, and both pieces had substantially the same amount of elastomeric material. Therefore, both pieces described above had essentially the same mass.

Such pieces were subjected to 100 cycles of tension and compression using a Zwick dynamometer, with the above pieces subjected to a load increasing to 12 N, between a maximum elongation of 1.5% (equivalent to 3 mm) and a minimum elongation of 0. 5% (equivalent to 1 mm), with an applied tension/compression rate of 50 mm/min. The average of the values obtained from the measurements performed gave as a value characterizing the dissipated energy a value equal to 2.05 for the known reinforcing cord and equal to 2.24 for the hybrid reinforcing cord type Ny 3×0.21 mm+Ny 1400 dTex , which confirms the better hysteresis characteristics of the hybrid reinforcing cord according to the invention compared to the known reinforcing cord containing only multifilament textile yarns. This confirmed that it is advisable to use a hybrid reinforcing cord of the Ny 3×0.21 mm+Ny 1400 dTex type in the tire carcass structure.

The Applicant has also carried out comparative tests to determine the flexural stiffness of a hybrid PET 3 x 0.40 mm+Ar 1100 dTex type reinforcement cord in comparison with the flexural stiffness of a known 3 x 0.175 mm type reinforced cord made of steel. For this purpose, a sample was made from a vulcanized elastomeric material containing many hybrid reinforcing cords of the PET 3×0.40 mm+Ar 1100 dTex type with a density of 80 cords per 1 dm (8 cords per 1 cm), and a sample from a vulcanized elastomeric material , containing a variety of known reinforcing cords of the 3 × 0.175 mm type, made of steel, with a density of 130 cords per 1 dm (13 cords per 1 cm).

The sample containing PET 3×0.40 mm+Ar 1100 dTex hybrid reinforcing cords had an elastomeric material thickness of approximately 1.30 mm and a weight of approximately 1480 g/ ^m2 , while the sample containing the known metal reinforcing cords, had an elastomeric material thickness of approximately 0.80 mm and a weight of approximately 1470 g/m ² .

Both specimens described above were subjected to the ring failure rigidity test as follows: the specimens were bent and welded to create corresponding rings with a diameter of 80 mm. Such specimens were subjected to an initial pre-tension load of 0.5 N and a compression load of 25 mm at a compression rate of 100 mm/min.

The sample containing hybrid reinforcing cords type PET 3×0.40 mm+Ar 1100 dTex withstood a maximum force of 0.95 N, while the sample containing known metal reinforcing cords withstood a maximum force of 0.86 N , which confirms the better characteristics of the hybrid reinforcing cord according to the invention, associated with flexural rigidity, compared to the known metal reinforcing cord. This confirmed that it is advisable to use a hybrid reinforcing cord of the PET 3×0.40 mm+Ar 1100 dTex type in the belt structure of the tire, as well as in the bead tape and/or the wing tape.

The Applicant has also carried out comparative tests to determine the compressive load resistance of a hybrid PET 3 x 0.40 mm+Ar 1100 dTex type reinforcement cord in comparison with the compressive load resistance exhibited by known 3 x 0.175 mm type reinforcement cords made of steel.

The applicant has indeed established through observation that, in particular in the case of the belt structure and side strip and/or wing strip, of the stresses that can lead to a reduction in the service life of the reinforcing cords, those caused by dynamic compressive loads are of particular importance. In particular, when subjected to repeated compressive loads, the reinforcing cords used in the above-mentioned tire structural components deform, forming waves that result in “unraveling,” i.e., separation of the individual monofilament/multifilament yarns from each other, resulting in tire failure. .

To evaluate the behavior of the reinforcing cords under the above-mentioned compressive loads, two samples were prepared, each containing two strips of vulcanized elastomeric material, each strip containing a plurality of parallel reinforcing cords and the two strips being inclined relative to each other at an angle of approximately 30° .

One of the two samples (hereinafter referred to as “sample A”) contained hybrid reinforcing cords of the PET 3×0.40 mm+Ar 1100 dTex type with a density of 80 cords per 1 dm (8 cords per 1 cm), while the other sample (hereinafter referred to as "sample B") contained known reinforcing cords of the 3 x 0.175 mm type, made of steel, with a density equal to 130 cords per 1 dm (13 cords per 1 cm).

Sample A had an elastomeric material thickness of approximately 1.30 mm and a mass of approximately 1480 g/ ^m2 , while Sample B had an elastomeric material thickness of approximately 0.80 mm and a mass of approximately 1470 g / ^m2 .

These two samples were cured at 170°C for 10 minutes and kept at indoor temperature for 16 hours.

Each of these two specimens was subjected to bending/compression cycles in a De Mattia testing machine until failure occurred.

Sample A demonstrated resistance for a period of time approximately 40% greater than the corresponding period of time for sample B. This confirmed that it is advisable to use a hybrid reinforcing cord of the PET 3×0.40 mm + Ar 1100 dTex type in the tire belt structure, as well as in the side tape and/or wing tape.

In general, the comparative tests discussed above indicate that, with essentially the same mass of the semi-finished product containing reinforcing cords:

- hybrid reinforcing cords of type Ny 3×0.21 mm+Ny 1400 dTex have better characteristics related to hysteresis, relatively corresponding to the characteristics of known reinforcing cords of type 2 × Ny 1400 dTex, therefore, hybrid reinforcing cords of type Ny 3×0.21 mm +Ny 1400 dTex are suitable for use in carcass tires;

- hybrid reinforcing cords of type PET 3 × 0.40 mm + Ar 1100 dTex have better characteristics related to flexural rigidity and resistance to compressive loads, relatively corresponding to the characteristics of known reinforcing cords type 3 × 0.175 mm, made of steel and currently used in breaker structure, as well as in the bead and/or fender strip, therefore, hybrid reinforcing cords of the type PET 3×0.40 mm+Ar 1100 dTex are suitable for use in the breaker structure, as well as in the bead and/or fender strip of tires.

The present invention has been described with reference to certain preferred embodiments. Various modifications may be made to the embodiments described above while still remaining within the scope of the invention as defined by the claims below.

Claims (22)

1. A tire (100) for vehicle wheels, comprising a support structure (100a) and a tread band (109) located at a radially outer location relative to the support structure (100a), wherein the support structure (100a) contains a plurality of hybrid reinforcing cords (10 ), each of which has a plurality of monofilament textile threads (20) twisted with at least one multifilament textile thread (30), and in any cross section of the hybrid reinforcing cord (10) at least one portion of at least one monofilament textile thread (20) from said plurality of monofilament textile threads (20) forms a first portion of the radially outer surface of the hybrid reinforcing cord (10) and at least one portion of said at least one multifilament textile thread (30) forms a second portion of the radially outer surface of the hybrid reinforcing cord (10). 2. The tire (100) according to claim 1, wherein said first radially outer surface portion is formed by at least one portion of at least two of said monofilament textile yarns (20). 3. The tire (100) according to claim 1 or 2, wherein said plurality of monofilament textile threads (20) are twisted together with a predetermined first twisting step (P1) to form a strand of monofilament textile threads, and said at least one multifilament textile thread (30) is twisted together with the specified strand of monofilament textile yarns with a given second pitch (P2) of twisting. 4. The tire (100) according to claim 1 or 2, wherein at least one first monofilament textile thread (20) of said plurality of monofilament textile threads (20) is twisted together with said at least one multifilament textile thread (30) with a predetermined first twisting step (P1) to form a strand of mono- and multifilament textile threads, and at least one second monofilament textile thread (20) from said plurality of monofilament textile threads (20) is twisted together with said strand of mono- and multifilament textile threads threads with a given second pitch (P2) of twisting. 5. The tire (100) according to claim 1 or 2, wherein each monofilament textile thread (20) of said plurality of monofilament textile threads (20) is twisted together with at least one more monofilament textile thread (20) of said plurality of monofilament textile threads threads (20) and with said at least one multifilament textile thread (30) with a given pitch (P1) of twisting to form a strand of mono- and multifilament textile threads. 6. The tire (100) as claimed in any one of the preceding claims, wherein each monofilament textile yarn (20) of said plurality of monofilament textile yarns (20) is formed from aliphatic polyamide fibers, polyester fibers, polyaryletherketone fibers, or mixtures thereof. 7. The tire (100) according to any one of the preceding claims, wherein said at least one multifilament textile thread (30) contains textile continuous fibers (31) formed from aromatic polyamide fibers, aliphatic polyamide fibers, polyester fibers, polyketone fibers, polyvinyl alcohol fibers, cellulose fibers, glass fibers, carbon fibers or mixtures thereof. 8. The tire (100) according to any one of the preceding claims, wherein each monofilament textile thread (20) of said plurality of monofilament textile threads (20) has a diameter in the range between about 0.1 mm and about 1 mm. 9. The tire (100) according to any one of the preceding claims, wherein said hybrid reinforcing cord (10) contains monofilament textile yarns (20) in an amount ranging between 2 and 10. 10. The tire (100) according to any one of the preceding claims, wherein said at least one multifilament textile thread (30) has a linear density in the range between about 400 dtex and about 4500 dtex. 11. The tire (100) according to any one of the preceding claims, wherein said hybrid reinforcing cord (10) contains multifilament textile threads (30) in an amount ranging between 1 and 4. 12. The tire (100) as claimed in any one of the preceding claims, wherein at least some of said hybrid reinforcing cords (10) comprise at least one metal wire (50) wound spirally around said plurality of monofilament textile yarns (20) and said at least one multifilament textile thread (30). 13. The tire (100) according to any one of the preceding claims, wherein said at least one multifilament textile thread (30) contains at least one textile monofilament fiber (31) and a plurality of textile continuous fibers (32), in any cross section hybrid reinforcing cord (10), said at least one textile monofilament fiber (31) is at least partially located between said textile continuous fibers (32). 14. The tire (100) as claimed in any one of the preceding claims, wherein the support structure (100a) comprises: - a frame structure (101) containing at least one frame layer (111) having opposite end edges (101a) connected to corresponding annular fixing structures (102) to form corresponding side structures (103) on sides opposite relative to the equatorial plane (M-M) tires (100); - a belt structure (106) located in a radially outer location relative to the frame structure (101) and in a radially inner location relative to the tread band (109); wherein the hybrid reinforcing cords (10) are located in at least one of: - frame structure (101); - belt structure (106); - at least one stiffening layer (120, 121) connected to said at least one frame layer (111) adjacent to or near the corresponding end edge (101a). 15. The tire (100) of claim 14, wherein the belt structure (106) comprises a reinforcing layer (106c) which has cords angled at zero degrees and which is located at a radially inward location relative to the tread band (109) , wherein the reinforcing layer (106c) with cords located at an angle of zero degrees contains a plurality of said hybrid reinforcing cords (10). 16. Hybrid reinforcing cord (10), containing a plurality of monofilament textile threads (20) and at least one multifilament textile thread (30), twisted with the specified plurality of monofilament textile threads (20), while in any cross section of the hybrid reinforcing cord ( 10) at least one part of at least one monofilament textile thread (20) from the specified plurality of monofilament textile threads (20) forms the first section of the radially outer surface of the hybrid reinforcing cord (10) and at least one part of the specified at least one multifilament textile thread (30) forms a second section of the radially outer surface of the hybrid reinforcing cord (10).