RU2775036C1 - Tire for vehicle wheels - Google Patents

Abstract

FIELD: tire industry.

SUBSTANCE: tire contains a support structure and a tread bracelet located in a radially external location with respect to the support structure. The support structure contains a variety of hybrid reinforcing cords (10). Each of the hybrid reinforcing cords (10) has at least two complex threads (20) twisted together with a given twisting step (P). Each of these at least two complex threads (20) contains at least one monofilament textile thread (21) and at least one multifilament textile thread (22) containing a plurality of textile continuous fibers (22a). In any cross–section of the hybrid reinforcing cord (10), the specified at least one monofilament textile thread (21) is at least partially inserted into the continuous fibers (22a) of the specified at least one multifilament textile thread (22).

EFFECT: improvement in the performance of the tire.

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 for high performance and ultra high performance cars.

Tires for high performance and ultra high performance vehicles, commonly referred to as "HP" or "UHP", are in particular tires that enable speeds in excess of 200 km/h, up to and above 300 km/h. Examples of such tires are tires belonging to the classes “T”, “U”, “H”, “V”, “Z”, “W”, “Y” according to the E.T.R.T.O.- (European Tire and Rim Technical Organization), and tires for racing cars, in particular for four-wheeled vehicles with a large cylinder displacement. As a rule, 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 preferably mounted on rims having rim diameters equal to or greater than 13 inches (330.2 mm), preferably not exceeding 24 inches (609.6 mm), more preferably between 16 inches and 23 inches (between 406, 4 mm and 584.2 mm).

However, the tire according to the invention can be used in vehicles other than the aforementioned vehicles, such as high performance sport bikes.

The tire of the invention comprises hybrid reinforcing cords as defined throughout this specification.

State of the art

Tires with reinforcing cords containing a core made of a textile material and a winding of one or more textile threads formed from a material different from the core material located around the core are described, for example, in US 7222481 B2, EP 3196343 A1, US 4343343 A1 , EP 329590A1.

The essence of the invention

Throughout this specification and in the following claims, when referring to certain values of certain angles, absolute values, i.e. both positive and negative values, relative to the reference plane or direction are meant, unless otherwise indicated.

In addition, when referring to any range of values between the minimum value and the maximum value, it is intended that the aforementioned minimum and maximum values are included in the above range, unless otherwise indicated.

In what follows, the following definitions apply.

The term "equatorial plane" of a tire is used to refer to a plane which 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 "radial inner/outer" and "axial inner/outer" are used with respect to a direction substantially parallel to the equatorial plane of the tire and to a direction substantially perpendicular to the equatorial plane of the tire, respectively, are relative 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/circumferential" are used in relation to the direction of the tire's circumferential extent, i.e. the direction of rolling of the tire, which corresponds to a direction "lying" in a plane coinciding with the equatorial plane of the tire or substantially parallel to equatorial plane of the tire.

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

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

The term "elastomeric material" or "elastomer" is used to refer to a material containing a natural or synthetic polymer that can be vulcanized and an active filler, such material at room temperature and after being vulcanized can have deformations caused by force, and capable of quickly and completely returning to substantially its original shape and size after removal of the deforming force (as defined by ASTM D1566-11 (American Society for Testing and Materials) Standard Rubber Terminology).

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

In the following, the term "wire/monofilament yarn" will be used to refer to one elongate element made of a metallic material or one elongate element consisting of a single textile continuous fiber (in this case, the expression "monofilament textile yarn" will also be used), while while the term "multifilament thread" will be used to refer to an elongated element consisting of an accumulation of a plurality of textile continuous fibers (in this case, the expression "multifilament textile thread" will also be used).

Each continuous fiber can also be defined as a "fiber".

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

Reinforcing textile cords may be marked with a symbol that represents the textile material, the fiber number used, and the number of threads forming the reinforcing cord. For example, the designation Ar1672 of a reinforcing cord with threads formed from aramid (aromatic polyamide) indicates a cord containing aramid fibers with a number of 1670 dtex and formed from two threads twisted together.

The term "strand/ply yarn" is used to refer to a combination of at least two monofilament yarns or multifilament yarns to form an elongate element intended to be twisted with at least another elongate element to form a reinforcing cord. The two multifilament yarns that form the reinforcing cord may be the same or may be different from each other.

The expression "hybrid reinforcing cord" is used to denote a reinforcing cord containing at least one monofilament textile thread and at least one multifilament textile thread, while the monofilament thread and the multifilament thread can be formed from the same textile material or from different textile materials.

The expression "non-hybrid reinforcing cord" is used to denote 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 the BISFA method E10 (International Bureau of Standards for Man-made Fibers, Internationally Harmonized Test Methods for Steel Tire Cords, 1995 edition).

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

The term "radial frame structure" is used to refer to a frame structure containing a plurality of reinforcing cords, each of which is oriented along a substantially axial direction. Such reinforcing cords may be included in a single carcass ply or in a plurality of carcass plies (preferably two) superimposed one on top of the other in the radial direction.

The term "cross-cord belt structure" is used to refer to a belt structure comprising a first belt ply, including reinforcing cords substantially parallel to each other and sloping with respect to the equatorial plane of the tire at a predetermined angle, and at least one second belt ply, located in a radially outer location with respect to the first belt layer and includes reinforcing cords substantially parallel to each other, but oriented with an inclination opposite to the inclination of the reinforcing cords of the first layer, relative to the equatorial plane of the tire.

The term "zero-degree cord belt layer" is used to refer to a reinforcing layer containing at least one reinforcing cord wound around the belt structure in accordance with the winding direction substantially along the circumference.

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

The term "linear density" or "number" of the cord or monofilament yarn/multifilament yarn is used to refer to the weight of the cord or monofilament yarn/multifilament yarn per unit length. Linear density can be measured in dtex (grams per 10 km length). For the determination of linear density, reference should be made to even monofilament yarns/multifilament yarns without twists applied in the test phase or in the twisting phase, according to the tests regulated by BISFA. For example, you should mention:

for aramid fibers (AR):

- Test Methods for Para-Aramid Filament Yarn, 2002 Edition

-- Determination of Linear Density - Chapter 6

-- Determination of mechanical tensile 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 yarns of viscose, ammonium copper, acetate, triacetate continuous fibers and lyocell fibers - 2007 edition, Determination of tensile mechanical properties - Chapter 7 - Tensile test conditions: oven-dry test - Table 7.1 - Test procedure - Clause 7.5 - Oven-drying test for samples subjected to relaxation - Subclause 7.5.2.4.

Sports car tires must have high ground traction to enable the high torque to which they are subjected to be effectively transmitted to the ground, and thus achieve high traction and effective braking force. Such tires must also be lightweight and provide adequate response to the lateral loads that the tire is subjected to during cornering.

Sports car tires typically comprise a radial carcass structure extending between opposing bead structures, a criss-cross belt structure located at a radially outward position with respect to the carcass structure, a reinforcing layer having cords arranged at an angle of zero degrees, and located in a radially outer position with respect to the criss-crossed belt structure, and a tread band located in a radially outer position with respect to the reinforcing layer with cords located at an angle of zero degrees.

The carcass structure is designed to give the tire the desired 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 - which the tire is subjected to during movement in contact with the road surface , - carcass structure to give the tire the desired performance characteristics (i.e. grip, road stability, handling, directionality, road holding) and provide comfort. On the other hand, the reinforcing layer with cords arranged at an angle of zero degrees is intended 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 an appropriate slope with respect to the circumferential or rolling direction.

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 tires produced by him, including tires for sports cars.

Thus, Applicant hypothesized the use of reinforcing cords, which are as light as possible, in his sports car tires and therefore focused on textile reinforcing cords.

The Applicant has found as a result of observation that even based on the type of elongated elements used in the reinforcing cord (monofilament textile yarns, multifilament textile yarns and/or possible combination of one or more of the aforementioned monofilament yarns with one or more of the aforementioned multifilament yarns) it is possible to produce many hybrid reinforcing cords having characteristics that are theoretically suitable for use in the carcass and/or belt structure of sports car tires.

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

The Applicant has taken into account that in any type of vehicle tyre, it is necessary to provide good adhesive adhesion of the reinforcing cords to the surrounding elastomeric material. This leads to the use of reinforcing cords containing multifilament textile yarns in tires.

However, in order to reduce hysteresis problems, as well as to give the aforementioned reinforcing cords the desired resistance to the compressive loads that the reinforcing cords may be subjected to, monofilament textile yarns as mentioned above are most suitable.

In resolving this contradiction, the Applicant has found that a hybrid reinforcing cord formed by twisting together at least two multifilament yarns of a textile material, in which each of the aforementioned multifilament yarns contains at least one multifilament textile yarn and a monofilament textile yarn arranged so that in all cross-sections of the reinforcing cord, the monofilament textile yarn is at least partially embedded or “embedded” in the continuous fibers of at least one multifilament textile yarn, has very good adhesion to the surrounding elastomeric material, very good fatigue resistance and an optimum compromise combination of characteristics associated with both bending and compression resistance and hysteresis.

In addition, due to the aforementioned “switching on”, the hybrid reinforcement cord exhibits a substantially isostatic behavior when subjected to a compressive load, i.e. all components of the reinforcement cord (monofilament textile yarns and continuous fibers of multifilament textile yarns) are loaded in essentially the same way.

In the Applicant's opinion, if special attention is paid to adhesive bonding, it should be noted that even only partial coverage of a monofilament textile yarn with continuous fibers of a multifilament textile yarn guarantees that in each cross section of the reinforcing cord there will be at least one sufficiently large area of the outer surface of the reinforcing a cord which is formed by continuous fibers of a multifilament textile yarn and therefore has a very good adhesive bonding ability to the surrounding elastomeric material. Such adhesive bonding is the greater, the greater is that part of the monofilament textile thread, which in any cross-section of the hybrid reinforcing cord is covered by the multifilament textile thread.

Therefore, according to 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 outward position with respect to the support structure.

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

Each of said hybrid reinforcing cords preferably comprises at least two multifilament yarns twisted together with a predetermined twist pitch.

Each of said at least two multifilament yarns preferably comprises at least one monofilament textile yarn and at least one multifilament textile yarn containing a plurality of textile continuous fibers.

In any cross section of the hybrid reinforcing cord, said at least one monofilament textile yarn is preferably at least partially embedded in continuous fibers of said at least one multifilament textile yarn.

The use of such a hybrid reinforcing cord makes it possible not to reduce the advantages associated with adhesive bonding due to the presence of multifilament textile yarns, while at the same time providing the advantages discussed above regarding hysteresis and resistance to compressive loads. In particular, due to the fact that the monofilament textile yarn is always at least partially embedded in or surrounded by continuous fibers of the multifilament textile yarn, the outer surface of the hybrid reinforcing cord will be mainly formed by the continuous fibers of the multifilament textile yarn to provide greater adhesive adhesion to the surrounding elastomeric material. .

In addition, having two multifilament yarns of the type described above twisted together makes it possible to increase the fatigue resistance of the reinforcing cord while maintaining the advantages discussed above.

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

The hybrid reinforcing cord preferably comprises at least two multifilament yarns twisted together at a predetermined twist pitch.

Each of said at least two multifilament yarns preferably contains at least one monofilament textile yarn.

Each of said at least two multifilament yarns preferably contains at least one multifilament textile yarn containing a plurality of textile continuous fibers.

In any cross section of the hybrid reinforcing cord, said at least one monofilament textile yarn is preferably at least partially embedded in continuous fibers of said at least one multifilament textile yarn.

The Applicant believes that the above-described hybrid reinforcing cords can be used in all types of vehicle tires where high performance is required, hence not only in sports cars, but also, for example, in sports motorcycles, while achieving the advantages discussed above.

As discussed below, the Applicant also contemplates that the above-described hybrid reinforcing cords can be used in both the carcass structure and the belt structure of a tire (both or only one of the aforementioned structures).

The Applicant also contemplates that the above-described hybrid reinforcing cords can also be used, or only, in other tire reinforcing components, such as, for example, the tire reinforcing components described below and referred to as "wing tape" and "bead tape" as a substitute for conventional metal cords. (with the corresponding advantages of reduced tire mass, the ability to identify the tire by radio frequency identification (RFID) and the ability to run with a flat tire without the risk of overheating the reinforcing cords), and instead of conventional textile cords containing only multifilament textile yarns (with the corresponding advantages, related to stiffness, fatigue resistance and performance).

In the Applicant's opinion, in the particular case of application in belt structures, it is also possible to obtain a reduction in resonant frequencies, resulting in noise-related advantages.

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

In any cross-section of the hybrid reinforcing cord, preferably at least 50% of the outer surface of the monofilament textile yarn is located between the continuous fibers or inserted into the continuous fibers of the at least one multifilament textile yarn. Thus, a possible part of the outer surface of the monofilament textile yarn, which in each cross section of the hybrid cord will be directly exposed to the surrounding elastomeric material, will have such an extension that the very good adhesive adhesion of the hybrid reinforcing cord to the surrounding elastomeric material is not impaired.

In some preferred embodiments, each multifilament yarn comprises one monofilament textile yarn and one multifilament textile yarn.

In this case, in any cross section of the hybrid reinforcing cord, preferably at least 50% of the outer surface of each monofilament textile yarn is located between the continuous fibers or is embedded in the continuous fibers of the respective multifilament textile yarn. Thus, the likelihood of having a portion of the outer surface of the monofilament textile yarn directly exposed to the elastomeric material will be extremely low.

In other embodiments, each multifilament yarn comprises more than one monofilament textile yarn (eg, two monofilament textile yarns) and one multifilament textile yarn.

In further embodiments, each multifilament yarn comprises one monofilament textile yarn and more than one multifilament textile yarn (eg, two multifilament textile yarns).

In further embodiments, each multifilament yarn comprises more than one monofilament textile yarn (eg, two monofilament textile yarns) and more than one multifilament textile yarn (eg, two multifilament textile yarns).

In all of the embodiments, the twist pitch P is preferably greater than about 1 mm, more preferably greater than about 2 mm.

The twist pitch P is preferably less than about 20 mm, more preferably less than about 15 mm.

In preferred embodiments, the twist pitch is between about 1 mm and about 20 mm, more preferably between about 2 mm and about 15 mm.

Said at least one monofilament textile thread is preferably twisted on its own/around itself with a predetermined first twisting pitch. The Applicant has found from observation that such a measure helps to optimize the fatigue behavior of the reinforcing cord.

Said first twist pitch is preferably equal to said predetermined twist pitch. In this way, the maximum insertion of the monofilament textile yarns into the continuous fibers of the corresponding multifilament textile yarns is ensured, which greatly improves the adhesion of the reinforcing cord to the surrounding elastomeric material.

Said at least one multifilament textile thread may or may not be twisted by itself with a predetermined second twist pitch. With a given twist, the second twist pitch is preferably equal to the specified twist pitch. This is provided to ensure maximum insertion of the monofilament textile yarns into the continuous fibers of the multifilament textile yarns.

In some preferred embodiments, said at least one multifilament textile yarn is substantially parallel to said at least one monofilament textile yarn.

In other preferred embodiments, continuous fibers of said at least one multifilament textile yarn are helically wound on said at least one monofilament textile yarn with a predetermined winding pitch.

As in the previous embodiment, in order to ensure maximum insertion of the monofilament textile yarns into the continuous fibers of the multifilament textile yarns, the specified winding pitch is preferably equal to the specified twisting pitch.

Said at least one monofilament textile yarn is preferably formed from fibers of aliphatic polyamides (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 (eg polybutylene terephthalate, polyethylene terephthalate, polyethylene isophthalate), polyaryletherketone fibers (eg polyetheretherketone) or mixtures thereof.

The continuous fibers of said at least one multifilament textile yarn are preferably 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 6.12), polyester fibers (e.g. polybutylene terephthalate, polyethylene terephthalate, polyethylene isophthalate), polyketone fibers, polyvinyl alcohol fibers, cellulose fibers (e.g. rayon fibers, lyocell fibers), glass fibers, carbon fibers or mixtures thereof.

Said at least one monofilament textile thread preferably has a diameter greater than about 0.10 mm, more preferably greater than about 0.15 mm.

Said at least one monofilament textile thread preferably has a diameter of less than about 0.70 mm, more preferably less than about 0.50 mm.

In preferred embodiments, said at least one monofilament textile yarn has a diameter in the range between about 0.10 mm and about 0.70 mm, more preferably between about 0.15 mm and about 0.50 mm.

As a rule, it is preferably provided that the more monofilament textile yarns are contained in each multifilament yarn of the hybrid reinforcing cord, the smaller the diameter of said monofilament textile yarns.

Said at least one multifilament textile thread preferably has a linear density greater than about 400 dtex, more preferably greater than about 800 dtex.

Said at least one multifilament textile thread preferably has a linear density of less than about 4000 dtex, more preferably less than about 2500 dtex.

In preferred embodiments, said at least one multifilament textile yarn has a linear density in the range between about 400 dtex and about 4000 dtex, more preferably between about 800 dtex and about 2500 dtex.

Said support structure preferably comprises a carcass structure comprising at least one carcass ply having opposite end edges folded around respective annular anchor structures to form respective bead structures on sides opposite the equatorial plane of the tire.

Said support structure preferably comprises a criss-cross belt structure located in a radially outward position with respect to the carcass structure and in a radially inward position with respect to the tread band.

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

Said support structure preferably comprises at least one stiffening layer bonded to said at least one carcass layer adjacent to or adjacent to a respective folded end edge, and said plurality of hybrid reinforcing cords located in said at least one layer giving rigidity.

Said at least one stiffening layer can preferably be connected to said at least one carcass layer adjacent to or adjacent to a respective side structure.

Said at least one stiffening layer may advantageously be located between a respective folded end edge of said at least one carcass layer and a respective side structure.

More preferably, said at least one stiffening layer may at least partially surround said side structure. Such a stiffening layer is also referred to as a "wing tape".

Alternatively or in addition, said at least one stiffening layer may be connected to a corresponding folded end edge of said at least one carcass layer at an axially outward location with respect to the respective annular retaining structure.

More preferably, said at least one stiffening layer may extend from said annular retaining structure towards said tread band. Such a stiffening layer is also referred to as a "bead tape".

The bead tape can be located at an axially outer location or at an axially inner location with respect to the end edge of said at least one carcass ply. In the case where the carcass structure comprises many carcass plies, for example two, the bead strip may be located between the respective end edges of the different carcass plies.

In all embodiments and in all applications discussed above, the zero degree cord reinforcement layer preferably comprises non-hybrid reinforcing cords, which preferably comprise only monofilament textile yarns or multifilament textile yarns formed from, for example, aramid or nylon.

However, embodiments are envisaged in which the zero degree cord breaker ply comprises hybrid reinforcing cords of the type described above.

In the first preferred embodiments of a tire in which said plurality of hybrid reinforcing cords are arranged in a carcass structure, each of said hybrid reinforcing cords comprises two multifilament yarns twisted together, each of the multifilament yarns comprising a monofilament textile yarn formed from nylon and having a diameter of about 0.23 mm and a multifilament textile thread formed from nylon and having a linear density of about 940 dtex. Such a tire is particularly suitable for use in high performance and ultra high performance vehicles as defined above.

In second preferred embodiments of a tire in which said plurality of hybrid reinforcing cords are disposed in a carcass structure, each of said hybrid reinforcing cords comprises two multifilament yarns twisted together, each of the multifilament yarns comprising a monofilament textile yarn formed from nylon and having a diameter , equal to approximately 0.23 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 performance sport bikes.

In the first preferred embodiments of a tire in which said plurality of hybrid reinforcing cords are arranged in a criss-cross cord breaker structure, each of said hybrid reinforcing cords comprises two multifilament yarns twisted together, each of the multifilament yarns comprising a monofilament textile yarn formed from PET. (polyethylene terephthalate) and having a diameter of approximately 0.30 mm, and a multifilament textile thread formed from aramid and having a linear density of approximately 1680 dtex. Such a tire is particularly suitable for use in the high performance and ultra high performance vehicles defined above and is stronger or stiffer than current tires manufactured by the Applicant which contain non-hybrid textile reinforcing cords in a crisscross cord construction.

In a second preferred embodiment of a tire in which said plurality of hybrid reinforcing cords are arranged in a crisscross cord breaker structure, each of said hybrid reinforcing cords comprises three multifilament yarns twisted together, each of the multifilament yarns comprising a monofilament textile yarn formed from PET (polyethylene terephthalate) and having a diameter of approximately 0.40 mm, and a multifilament textile thread formed from aramid and having a linear density of approximately 1100 dtex. Such a tire is particularly suitable for use in the high performance and ultra high performance vehicles defined above and is lighter as well as more amenable to radio frequency identification (RFID) identification than the Applicant's current tires which contain a crossover belt structure. cords metal reinforcing cords.

In preferred embodiments of a tire in which said plurality of hybrid reinforcing cords are located in said at least one stiffening layer, e.g., in a bead or wing tape, the hybrid reinforcing cords are identical to the hybrid reinforcing cords described above for belt applications. structures with crossed cords.

Said carcass structure preferably comprises one carcass ply, and said plurality of hybrid reinforcing cords are located in said one carcass ply. In this way, an advantageous weight reduction is achieved while maintaining the benefits of hysteresis and unchanged stiffness.

In some embodiments, at least some of said hybrid reinforcing cords comprise at least one metal wire wound helically around said at least two multifilament yarns twisted together.

The aforementioned metal wire preferably helps to increase the strength of the reinforcing cord and to keep said at least two complete threads tightly twisted together, while on the other hand, there are no obstacles to the identification process by radio frequency identification (RFID).

The winding direction of the metal wire on said at least two multifilament yarns twisted together may or may not be the same as the twisting direction of said at least two multifilament yarns.

The aforementioned winding direction is preferably opposite to the twisting direction of said at least two multifilament yarns.

The metal wire is preferably wound on said at least two multifilament yarns twisted together with a winding pitch greater than about 2 mm, more preferably greater than about 3.5 mm.

The metal wire is preferably wound on said at least two multifilament filaments twisted together 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 said at least two multifilament filaments twisted together 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 aforementioned metal wire are preferably used in criss-cross cord constructions and/or in the aforementioned 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 bonding capability to further improve adhesive bonding to the elastomeric material in which they are embedded or coated.

Description of embodiments of the invention

Additional features and advantages of the tire according to the present invention will become clearer from the following detailed description of the preferred embodiments thereof, made with reference to the attached drawings, in which:

fig. 1 is a schematic representation of a part of a tire according to an embodiment of the present invention in partial half section;

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 an enlarged schematic cross-sectional view of the hybrid reinforcing cord of FIG. 2 included in the tire part of FIG.

fig. 4 is a schematic perspective view of the hybrid reinforcement cord of FIG. 2 in which some of the cord components have been removed to show other components that would otherwise be hidden;

fig. 5 is a schematic perspective view of a second embodiment of the hybrid reinforcing cord of FIG. 2 in which some of the cord components have been removed to show other components that would otherwise be hidden; and

fig. 6 is a schematic side view of a portion of the second embodiment hybrid reinforcing cord used in the tire of FIG.

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

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 and/or high or ultra high performance vehicles.

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

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

The support structure 100a comprises a frame structure 101, which in turn comprises 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 a similar application in tires containing more than one carcass ply.

The carcass ply 111 has end edges axially opposite and in contact with corresponding annular retaining structures 102, called bead cores, optionally connected to an elastomeric filler 104. structure 103, referred to as the "bead structure" and designed to enable the tire 100 to be held/fixed on a corresponding mounting rim, not shown.

The carcass ply 111 comprises a plurality of reinforcing cords 10' coated with elastomeric material or embedded in a matrix of crosslinked elastomeric material.

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

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

In an embodiment, the connection between the carcass structure 101 and the annular reinforcement structure 103 may be made by means of a second carcass ply (not shown in FIG. 1) superimposed at a radially outer location with respect to the carcass ply 111.

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

The support structure 100a comprises, at a radially outer location with respect to the frame structure 101, a criss-cross belt structure 106 comprising at least two belt layers 106a, 106b superimposed on each other in the radial direction.

The breaker layers 106a, 106b respectively comprise a plurality of reinforcing cords 10a, 10b. Such reinforcing cords 10a, 10b are slanted with respect to the circumferential direction of the tire 100, or relative to the MM equatorial plane of the tire 100, at an angle in the range between about 15° and about 45°, preferably between about 20° and about 40°. For example, such an angle is approximately 30°.

The support structure 100a may also include an additional breaker ply (not shown) located between the skeleton structure 101 and the breaker ply closest to the center in the radial direction of the aforementioned breaker plies 106a, 106b, and containing a plurality of reinforcing cords having an orientation inclined with respect to the longitudinal direction. the circumference of the tire 100 or relative to the equatorial plane M-M of the tire 100 at an angle of approximately 90°.

The support structure 100a may also include an additional breaker ply (not shown) located at a radially outward location with respect to the breaker ply most radially outward from the center of the aforementioned breaker plies 106a, 106b, and containing a plurality of reinforcing cords having an orientation inclined relative to direction along the circumference of the tire 100 or relative to the equatorial plane M-M of the tire 100 at an angle in the range between about 20° and about 70°.

The reinforcing cords 10a, 10b of the breaker ply 106a, 106b are parallel to each other and have a criss-crossing orientation with respect to the reinforcing cords of the other breaker ply 106b, 106a.

In ultra-high performance tires, the belt structure 106 may be a criss-cross, wraparound belt structure. Such a belt structure is formed by placing at least one belt layer on the support element and bending opposite side end edges of said at least one belt layer. Preferably, first the first breaker layer is applied to the support element, then the support element is expanded in the radial direction, after that the second breaker layer is applied to the first breaker layer, and finally the axially opposite, end edges of the first breaker layer are folded over the second breaker layer for at least the measure of partial closure of the second breaker layer, which is the layer most distant from the center in the radial direction. In some cases, the third belt layer may be placed on top of the second belt layer. Folding axially opposite end edges of a belt ply over another belt ply located at a radially outward location preferably provides more responsiveness and sensitivity to the tire when cornering.

The support structure 100a comprises, at a position radially outward of the criss-cross belt structure 106, at least one reinforcing layer 106c having cords at an angle of zero degrees, commonly known as a "angled cord breaker". being zero degrees. It contains reinforcing cords 10 s oriented essentially in the direction along the circumference. Thus, such reinforcing cords 10c form an angle of several degrees (typically less than about 10°, such as between about 0° and 6°) relative to the M-M equatorial plane of the tire 100.

The reinforcing cords 10a, 10b, 10c are covered with elastomeric material or embedded in a matrix of crosslinked elastomeric material.

A tread band 109 made of an elastomeric material is applied at a radially outward location to the zero degree cord reinforcement layer 106c, similar to the other components of the semi-finished tire 100.

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

The abrasion resistance band 105, if provided, extends at least to the corresponding sidewall 108.

In some specific embodiments, like the embodiment shown and described herein, the stiffness of the sidewall 108 can be increased by providing a stiffening layer 120, commonly known as a "wing tape" or additional band-like insert, and which is designed to increase stiffness and integrity. an annular reinforcing structure 103 and a sidewall 108.

The wing tape 120 is wound around the respective bead core 102 and the elastomeric filler 104 so that it at least partially surrounds the annular reinforcement structure 103. designs 103.

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

In certain specific embodiments, like the embodiment shown and described herein, the bead structure 103 may also comprise an additional stiffening layer 121, which is commonly known by the name/term "bead tape" or security strip, and which is intended to increase stiffness and integrity of the annular reinforcing structure 103.

The bead band 121 is connected to the respective folded end edge of the carcass ply 111 at an axially outward location with respect to the respective annular reinforcement structure 103 and extends radially towards the sidewall 108 and tread band 109.

The wing tape 120 and the side tape 121 comprise reinforcing cords 10d (the reinforcing cords of the wing tape 120 are not visible in the attached figure) coated with an elastomeric material or embedded in a matrix of crosslinked elastomeric material.

The tread band 109 has, at its radially outer location, a rolling surface 109a intended to be in contact with the ground. The rolling surface 109a has circumferential grooves (not shown in FIG. 1) formed thereon, which 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. ).

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

In certain specific embodiments, like the embodiment shown and described herein, a strip 110 composed of an elastomeric material, commonly known as a "mini-sidewall", may optionally be provided at the junction between the sidewalls 108 and the tread band 109. The mini-sidewall 110, typically produced by extrusion together with the tread band 109, and the mini-sidewall 110 improves the mechanical interaction between the tread band 109 and the sidewalls 108.

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

In the case of tubeless tyres, a rubber layer 112, commonly known as a "sealer", may also be provided at a radially inward location with respect 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 reinforcing cords 10' provided in the carcass layer 111) and/or reinforcing cords 10a, 10b (preferably all reinforcing cords 10a provided in the breaker layer 106a and all reinforcing cords 10b, provided in the breaker layer 106b, even in the case where the breaker structure 106 is a criss-cross and fold-over breaker) and/or the reinforcing cords 10 from the wing tape 120 and/or the side tape 121 are hybrid reinforcing cords 10 of this type, as shown in Figures 2-6 and described below.

On the other hand, the reinforcing cords 10c are preferably non-hybrid reinforcing cords, that is, they are formed from a single textile material, preferably aramid or nylon.

As shown in FIGS. 2-4, the hybrid reinforcing cord 10 comprises two multifilament yarns 20 twisted together with a predetermined twist pitch P.

The two multifilament threads 20 are preferably identical to each other. Therefore, only one of them will be described in the following.

As shown in FIGS. 3 and 4, the multifilament yarn 20 comprises one monofilament textile yarn 21 and one multifilament textile yarn 22 formed by a plurality of fibers 22a. However, each multifilament yarn 20 may comprise more than one monofilament textile yarn 21 and more than one multifilament textile yarn 22.

In any cross section of the reinforcing cord 10, the monofilament textile yarn 21 is inserted into the continuous fibers 22a of the multifilament textile yarn 22.

In the embodiment shown in FIGS. 3 and 4, the monofilament textile yarn 21 in any cross section of the reinforcing cord 10 is completely embedded in the continuous fibers 22a of the multifilament textile yarn 22, and hence the aforementioned continuous fibers 22 are arranged around the monofilament textile yarn 21 so that that they completely surround the monofilament textile thread 21.

Therefore, in FIG. 2, the monofilament textile yarn 21 is not visible because it is completely covered by the continuous fibers of the multifilament textile yarn 22.

Although the embodiment of FIGS. 2-4 (and also, as will be seen later, the embodiment of FIGS. 5 and 6) in which the monofilament textile thread 21 is fully inserted in any cross section of the reinforcing cord 10 into the continuous fibers 22a of the multifilament textile yarn 22 is particularly preferred, equally preferred are embodiments in which, in any cross section of the reinforcing cord 10, the monofilament textile yarn 21 is only partially inserted into the continuous fibers 22a of the multifilament textile yarn 22, and in particular, those embodiments in which at least 50% of the outer surface of the monofilament textile yarn 21 is "embedded" into the continuous fibers 22a of the multifilament textile yarn 22.

The monofilament textile thread 21 runs along the longitudinal direction A shown in FIG.

The mutual arrangement of the monofilament textile yarn 21 and the continuous fibers 22a of the multifilament textile yarn 22 along the longitudinal direction A may be such that the monofilament textile yarn 21 will run substantially parallel to the continuous fibers 22a of the multifilament textile yarn 22, as shown in Fig. 4, or such that that the continuous fibers 22a of the multifilament textile yarn 22 will be helically wound on the monofilament textile yarn 21 with a predetermined winding pitch W, which is preferably equal to the twisting pitch P.

In this latter case, the twisting direction of the two multifilament yarns 20 is preferably the same as the winding direction of the continuous fibers 22a of the multifilament textile yarn 22 on the monofilament textile yarn 21, but opposite directions can be provided.

The twist pitch P is preferably between about 1 mm and about 20 mm, more preferably between about 2 mm and about 15 mm, eg about 12.5 mm.

Fig. 5 shows an embodiment of a hybrid reinforcing cord 10 which differs from the hybrid reinforcing cord 10 shown in FIGS. 2 and 3 only in that the monofilament textile yarn 21 is twisted by itself with a predetermined twist pitch T.

The twisting pitch T is preferably equal to the twisting pitch P.

The twisting direction of the monofilament textile yarn 21 may be the same or opposite to the twisting direction of the two multifilament yarns 20.

The monofilament textile thread 21 is formed from fibers of aliphatic polyamides, such as 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, such as polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polyethylene isophthalate (PEI), or polyaryletherketone fibers such as polyetheretherketone (PEEK), or mixtures thereof.

The continuous fibers 22a of the multifilament textile yarn 22 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 polyester fibers such as polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polyethylene isophthalate (PEI), or polyketone fibers, or polyvinyl alcohol fibers, or cellulose fibers, such as rayon fibers or lyocell fibers, or from glass fibers or carbon fibers, or from any mixture of the aforementioned fibers, or from aggregates of mixed fibers containing two or more of the materials listed above. Such combinations of mixed fibers are hereinafter referred to as "mixed fibers".

In the case of "mixed fibres", the fibers forming the continuous fibers 22a may, for example, comprise:

- 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 referred to hereinafter as "blended 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 referred to hereinafter 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 referred to hereinafter as "mixed fibers with a linear density of 1650 dtex").

Regardless of the particular type of textile material used for the continuous fibers 22a of the multifilament textile yarn 22, such material is suitably subjected to an adhesive bonding treatment to become adhesive on the surface to ensure proper adhesive bonding to the surrounding elastomeric material. Generally, the imparting of adhesive bonding may be carried out by coating with an adhesive agent or by chemical or physical treatment.

For example, imparting adhesive bonding capability is accomplished by dipping the hybrid reinforcing cord 10 into a solution containing an adhesive agent after twisting the two multifilament yarns 20 together.

The monofilament textile thread 21 preferably has a diameter in the range between about 0.10 mm and about 0.70 mm, more preferably between about 0.15 mm and about 0.50 mm, which also depends on the material from which it is formed and the tire zone 100, in which the hybrid reinforcing cord 10 is placed.

The multifilament textile thread 22 preferably has a linear density in the range between about 400 dtex and about 4000 dtex, preferably between about 800 dtex and about 2500 dtex, which also depends on the material from which the multifilament textile thread 22 is formed and the area of the tire 100 in which contains a hybrid reinforcing cord 10.

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

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

In other additional embodiments, only the reinforcing cords 10d, and not the reinforcing cords 10', 10a and/or 10b, 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 bead tape is not provided or is provided and contains non-hybrid reinforcing cords), only in the bead tape 121 (if it is provided and when on-board tape is not provided or is provided and contains non-hybrid reinforcing cords), or both in the wing tape 120 and in the side tape 121 (if both are provided).

Fig. 6 shows an embodiment of a hybrid reinforcing cord 10 which differs from the hybrid reinforcing cord 10 of the previous figures only in that the hybrid reinforcing cord 10 also comprises a metal wire 30 wound helically around two multifilament yarns 20 twisted together.

In the embodiment shown, the winding direction of the metal wire 30 is opposite to the twisting direction of the two multifilament yarns 20.

The metal wire winding 30 has a winding pitch preferably between about 2 mm and about 10 mm, more preferably between about 3.5 mm and about 5 mm, such as about 4 mm.

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

A hybrid reinforcing cord 10 has been produced for use in the carcass structure 101 of a tire 100 of the type shown in FIG. 20 twisted together, each containing a monofilament textile thread 21 formed from nylon and having a diameter of approximately 0.23 mm, and a multifilament textile thread 22 formed from nylon and having a linear density of approximately 940 dtex. Hereinafter, such cord marked 2x(Ny 0.23 mm+Ny 940 dTex).

A hybrid reinforcing cord 10 for use in the carcass structure of a tire for use in high performance sports motorcycles has been produced, and comprising two multifilament yarns 20 twisted together, each containing a monofilament textile yarn 21 formed from nylon and having a diameter of approximately 0.23 mm and a multifilament textile thread 22 formed from aramid and having a linear density of approximately 1100 dtex. Hereinafter, such a hybrid reinforcement cord 10 is designated 2x(Ny 0.23 mm+Ar 1100 dTex).

Another example of a hybrid reinforcing cord 10 manufactured by the Applicant and preferably intended for use in the carcass construction of high performance and ultra high performance automobile tires and/or high performance sports motorcycles is 2x(Ny 0.21 mm+Ny 1400 dTex ), that is, it contains two multifilament yarns 20 twisted together, each of which contains a monofilament textile yarn 21 formed from nylon and having a diameter of approximately 0.21 mm, and a multifilament textile yarn 22 formed from nylon and having a linear density , equal to approximately 1400 dtex.

A hybrid reinforcing cord 10 has been made for use in a crossover belt structure 106 of a tire 100 of the type shown in FIG. two multifilament yarns 20 each containing a monofilament textile yarn 21 formed from PET and having a diameter of approximately 0.30 mm and a multifilament textile yarn 22 formed from aramid and having a linear density of approximately 1680 dtex. the hybrid reinforcing cord 10 is designated 2x(PET 0.30 mm+Ar 1680 dTex).

A hybrid reinforcing cord 10 was made, also for use in a breaker construction 106 with crossed cords of a tire 100 of the type shown in FIG. of PET and having a diameter of approximately 0.40 mm, and a multifilament textile yarn 22 formed from aramid and having a linear density of approximately 1110 dtex. dtex).

The Applicant has also produced reinforcing cords 10 for the stiffening layer 121 of the tire 100. Such reinforcing cords 10 are of the same design and made from the same materials as described above for the cross-cord belt structure 106.

COMPARATIVE TESTS

For some of the reinforcing cords 10 described above, Applicant performed tests for comparison with conventional reinforcing cords. Some of these tests are discussed below.

A test was performed to measure the hysteresis (energy dissipated by friction between the monofilament filaments/continuous fibers) of a 200 mm piece of 2x(Ny 0.23 mm+Ny 940 dTex) type hybrid reinforcement cord, compared to the hysteresis of a 200 mm piece conventional reinforcing cord made by twisting together two multifilament nylon yarns with a linear density of 1400 dtex.

Both pieces described above were subjected to 100 cycles of tension and compression by means of a Zwick dynamometer, while the above pieces were subjected to a load increasing to 12 N between a maximum elongation of 1.5% (equivalent to 3 mm) and a minimum elongation , constituting 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 made gave as a value characterizing the dissipated energy a value equal to 2.45 for a conventional reinforcing cord and equal to 2.24 for a hybrid reinforcing cord type 2x(Ny 0.23 mm+Ny 940 dTex ), which confirms the better hysteresis behavior of the hybrid reinforcing cord according to the invention compared to a conventional reinforcing cord containing only a multifilament textile thread. This makes it expedient to use a 2x(Ny 0.23 mm+Ny 940 dTex) hybrid reinforcing cord in the carcass structure of the tire.

The 2x(Ny 0.23 mm+Ny 940 dTex) hybrid reinforcing cord was also subjected to a comparative test to determine its flexural stiffness (i.e., ability to withstand bending loads). For this, a sample was made from a vulcanized elastomeric material containing a plurality of hybrid reinforcing cords of the type 2x (Ny 0.23 mm + Ny 940 dTex) with a density of 108 cords per 1 dm, and a sample from a vulcanized elastomeric material containing a plurality of conventional reinforcing cords , each of which contains two complex threads of nylon with a linear density of 1400 dtex, with a density equal to 112 cords per 1 dm.

Both of the specimens described above were subjected to the Ring Break Stiffness test as follows: the specimens were bent and welded to create respective rings with a diameter of 80 mm. Such specimens were subjected to an initial pretension under a load of 0.5 N and a compression value of 25 mm at a compression rate of 100 mm/min.

The sample containing 2x(Ny 0.23 mm+Ny 940 dTex) hybrid reinforcing cords withstood a maximum force of 0.282 N, while the sample containing conventional reinforcing cords withstood a maximum force of 0.243 N, confirming the best the flexural stiffness characteristics of the hybrid reinforcing cord of the invention compared to a conventional reinforcing cord containing only a multifilament textile yarn. This makes it expedient to use a 2x(Ny 0.23 mm+Ny 940 dTex) hybrid reinforcing cord in the carcass structure of the tire.

The Applicant also performed comparative tests to determine the flexural stiffness of a 2x(PET 0.3 mm+Ar 1680 dTex) hybrid reinforcing cord in comparison to a conventional reinforcing cord. For this, a sample was made from a vulcanized elastomeric material containing a plurality of hybrid reinforcing cords of the 2x type (PET 0.30 mm + Ar 1680 dTex) with a density of 70 cords per 1 dm (7 cords per 1 cm), and a sample from a vulcanized elastomeric material containing a plurality of conventional metal reinforcing cords, each containing 3 steel wires with a diameter of 0.22 mm, twisted together, with the sample indicated last containing 11 cords in 1 cm.

Both specimens described above were subjected to the Ring Break Stiffness test described above.

The sample containing 2x(PET 0.30 mm+Ar 1680 dTex) hybrid reinforcement cords withstood a maximum force of approximately 3.2 N, while the specimen containing conventional metal reinforcement cords withstood a maximum force of approximately 2 .3 N, which confirms the better characteristics of the hybrid reinforcing cord according to the invention, associated with flexural rigidity, compared with conventional reinforcing cord. This makes it expedient to use a hybrid reinforcing cord of the 2x type (PET 0.30 mm + Ar 1680 dTex) in the breaker structure of the tire, as well as in the bead and/or wing tape.

The present invention has been described with reference to certain preferred embodiments. Various changes can be made to the embodiments described above, while still remaining within the scope of the invention, which is defined by the following claims.

Claims (28)

1. Tire (100) for vehicle wheels, containing a support structure (100a) and a tread band (109) located in a radially outer position with respect to the support structure (100a), while the support structure (100a) contains a plurality of hybrid reinforcing cords (10), wherein each of the hybrid reinforcing cords (10) has at least two multifilament yarns (20) twisted together with a predetermined pitch (P) of twisting, wherein each of said at least two multifilament yarns (20) contains: - at least one monofilament textile thread (21); - at least one multifilament textile thread (22) containing a plurality of continuous textile fibers (22a), moreover, in any cross section of the hybrid reinforcing cord (10), said at least one monofilament textile thread (21) is at least partially inserted into continuous fibers (22a) of said at least one multifilament textile thread (22). 2. Tire (100) according to claim 1, in which in any cross-section of the hybrid reinforcing cord (10) at least 50% of the outer surface of the monofilament textile thread (21) is introduced into the continuous fibers (22a) of the specified at least one multifilament textile threads (22). 3. Tire (100) according to claim 1 or 2, wherein said at least one monofilament textile thread (21) is twisted by itself with a predetermined first twist pitch (T). 4. Tire (100) according to claim 3, wherein the first twist pitch (T) is equal to the predetermined twist pitch (P). 5. Tire (100) according to any one of the preceding claims, wherein said at least one multifilament textile yarn (22) is substantially parallel to said at least one monofilament textile yarn (21). 6. Tire (100) according to any one of claims 1 to 4, wherein the continuous fibers (22a) of said at least one multifilament textile yarn (22) are wound helically around said at least one monofilament textile yarn (21) with a predetermined step (W) of winding. 7. Tire (100) according to claim 6, wherein the winding pitch (W) is equal to the twisting pitch (P). 8. Tire (100) according to any one of the preceding claims, wherein said at least one monofilament textile thread (21) is formed from aliphatic polyamide fibers, polyester fibers, polyaryletherketone fibers or mixtures thereof. 9. Tire (100) according to any of the preceding claims, wherein the continuous fibers (22a) of said at least one multifilament textile yarn (22) are formed from aromatic polyamide fibers, aliphatic polyamide fibers, polyester fibers, polyketone fibers , polyvinyl alcohol fibers, cellulose fibers, glass fibers, carbon fibers or mixtures thereof. 10. Tire (100) according to any one of the preceding claims, wherein each of said at least two multifilament yarns (20) comprises one monofilament textile yarn (21) and one multifilament textile yarn (22). 11. Tire (100) according to any one of the preceding claims, wherein said at least one monofilament textile thread (21) has a diameter in the range between about 0.10 mm and about 0.70 mm. 12. Tire (100) according to any one of the preceding claims, wherein said at least one multifilament textile thread (21) has a linear density in the range between about 400 dtex and about 4000 dtex. 13. Tire (100) according to any one of the preceding claims, wherein the support structure (100a) comprises: - frame structure (101) containing at least one layer (111) of the frame, having opposite end edges (101a), bent around the respective annular fixing structures (102) to form the corresponding side structures (103) on sides opposite to the equatorial plane (X) tires (100); - a belt structure (106) with crossed cords, located in a radially outer position relative to the frame structure (101) and in a radially inner position relative to the tread band (109); wherein said plurality of hybrid reinforcing cords (10) is 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 carcass layer (111) at or near the corresponding folded end edge (101a). 14. Tire (100) according to any one of the preceding claims, wherein at least some of the hybrid reinforcing cords (10) comprise at least one metal wire (30) wound helically around said at least two multifilament yarns (20) twisted together. 15. Tire (100) according to claim 14, in which said at least two complex threads (20) are twisted together in accordance with a given direction of twisting, and said at least one metal wire (30) is wound around said at least two multifilament threads (20) twisted together with the winding direction opposite to the specified twist direction. 16. A hybrid reinforcing cord (10) containing at least two complex threads (20) twisted together with a given pitch (P) of twisting, each of said at least two complex threads (20) containing: - at least one monofilament textile thread (21); - at least one multifilament textile thread (22) containing a plurality of continuous textile fibers (22a), moreover, in any cross section of the hybrid reinforcing cord (10), said at least one monofilament textile thread (21) is at least partially inserted into continuous fibers (22a) of said at least one multifilament textile thread (22).

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