Reinforcing cord for tyres for vehicle wheels and method for manufacturing such reinforcing cord

Abstract

The invention relates to a reinforcing cord (10) for tyres for vehicle wheels, comprising at least two elongated elements (11a, 11b) made of a non-metallic material, in which the at least one elongated element (11a) extends around a hollow space (10a) along a helical path at a predetermined pitch (E). The reinforcing cord (10) is obtained by winding the at least one elongate element (11a) around the at least one sacrificial elongate element at the predetermined pitch (E) to make a semi-finished product, and then removing the at least one sacrificial elongate element from the semi-finished product, thereby forming the empty space (10a).

Description

Technical Field

[0001] This invention relates to a reinforcing cord for a tire used in vehicle wheels.

[0002] The present invention also relates to a method for manufacturing such reinforcing cords.

[0003] The present invention also relates to a tire for a vehicle wheel that includes such reinforcing cords.

[0004] The reinforcing cord of the present invention has a geometry suitable for achieving high partial load elongation. Background Technology

[0005] US10,618,353B2 describes a fabric reinforcing cord comprising two or more yarns twisted together and made of aramid fibers. The high modulus of the aramid fibers imparts a desired stiffness to these reinforcing cords. To improve partial load elongation, during the manufacture of this reinforcing cord, the yarns are spaced apart and an RFL adhesive composition is inserted between them. When these reinforcing cords are pulled, the yarns move closer together, thereby compressing the adhesive composition and achieving the desired partial load elongation. As the load increases, the elongation is offset by the high modulus of the aramid fibers.

[0006] WO2012 / 083148A1, US2017 / 0274706A1 and US4,155,394A describe a fabric-reinforced cord comprising elongated elements made of a high-modulus, low-elongation material (aramid), said elongated elements being twisted to elongated elements made of a low-modulus, high-elongation material (nylon).

[0007] KR20110061110A describes a reinforcing cord comprising: at least one elongated element with high elongation made of nylon; at least one elongated element with medium elongation made of a material selected from polyester, polyethylene, polyvinyl acetate (PVA), rayon, lyocell, and PEN; and at least one elongated element with low elongation made of, for example, aramid, carbon fiber, or glass fiber. Summary of the Invention

[0008] In this specification and the appended claims, unless otherwise stated, when referring to certain angle values, these angle values ​​shall be regarded as absolute values, that is, positive and negative values ​​relative to a reference plane or direction.

[0009] Furthermore, unless otherwise explicitly stated, when referring to any range of values ​​between the minimum and maximum values, the aforementioned minimum and maximum values ​​are considered to be included within the aforementioned range.

[0010] Furthermore, even if not specifically described, all ranges include any combination of the stated minimum and maximum values ​​and include any intermediate ranges.

[0011] Unless otherwise specified, any numerical value is to be regarded as being preceded by the term “about” to indicate any value that is slightly different from the stated value, for example, taking into account typical dimensional tolerances in the reference field.

[0012] The following definitions apply in the following text:

[0013] The term "green tire" is used to refer to tires that have been produced by manufacturing processes but have not yet been molded and vulcanized.

[0014] The terms "tire" or "finished tire" are used to refer to tires obtained by molding and vulcanizing raw tires in a vulcanizing mold.

[0015] The term "ground contact area" of a tire is used to refer to the portion of the tire that contacts the ground or road surface when the tire is mounted on the rim and a predetermined vertical load is applied to the tire.

[0016] The term "parallel" is used not only to indicate a state of perfect parallelism, but also to indicate a state that deviates slightly from perfect parallelism, for example, by an angle of deviation of no more than 5°.

[0017] The term "vertical" is used not only to indicate a state that is perfectly perpendicular or orthogonal, but also to indicate a state that deviates slightly from a perfectly perpendicular or orthogonal state, for example, by an angle of deviation of no more than 5°.

[0018] The term "equatorial plane" in tire terminology refers to the centerline plane perpendicular to the tire's axis of rotation. The equatorial plane subdivides the tire into two generally symmetrical and identical parts.

[0019] The term "elastomer material" or "elastomer" is used to refer to a material comprising a vulcanizable natural or synthetic polymer and reinforcing fillers, wherein the material, when vulcanized at room temperature, is readily deformable under stress and is able to rapidly and positively recover its basic original shape and dimensions after the deformation force is removed (according to the definition of standard terms related to rubber in ASTM D1566-11).

[0020] The terms "upstream" and "downstream" are used with reference to a predetermined direction and a predetermined reference. Thus, assuming, for example, a direction from left to right and a reference taken along said direction, a "downstream" position relative to said reference indicates a position to the right of said reference, while a "upstream" position relative to said reference indicates a position to the left of said reference.

[0021] When referring to tires, the terms "circumferential" and "circumferentially" are used with reference to the direction of rolling of the tire, which corresponds to a direction lying on a plane that coincides with or is substantially parallel to the tire's equatorial plane. When referring to reinforcing cords, the same terminology is used with reference to the direction of rotation about the center of the reinforcing cord in any cross-section of the reinforcing cord.

[0022] When referring to tires, the terms "radial," "radial inward," and / or "radial outward" are used with reference to a direction substantially parallel to the tire's equatorial plane (i.e., substantially perpendicular to the tire's axis of rotation). Conversely, when referring to reinforcing cords, the same terms are used with reference to a direction substantially perpendicular to the longitudinal direction of the reinforcing cords.

[0023] When referring to tires, the terms "axial," "inward axial," and / or "outward axial" are used with reference to a direction substantially perpendicular to the tire's equatorial plane (i.e., substantially parallel to the tire's axis of rotation). Conversely, when referring to reinforcing cords, the same terms are used with reference to a direction substantially parallel to the longitudinal direction of the reinforcing cords.

[0024] The terms "longitudinal trajectory" and "longitudinal direction" of reinforcing cords refer to the trajectory and direction along which the centers of the circumferences of all cross sections of the external reinforcing cord follow each other.

[0025] When a reference line is fixed at the outermost radial point of the reinforcing cord, tangent to the reinforcing cord and pointing along the longitudinal direction of the reinforcing cord, if the distance from the center of the aforementioned circle to the reference line changes along the longitudinal direction of the reinforcing cord such that the difference between the maximum and minimum distances is greater than 150 μm, then the longitudinal trajectory is considered "non-linear".

[0026] The term "basic axial direction" is used to indicate a direction that is tilted at an angle between 70° and 90° relative to the equatorial plane of the tire.

[0027] The term "basic circumferential direction" is used to indicate a direction oriented at an angle between 0° and 10° relative to the equatorial plane of the tire.

[0028] The term "reinforced cord" or simply "cord" is used to refer to an elongated element comprising several elongated elements, which may be covered by or incorporated into a matrix of elastomeric material.

[0029] The term "slender element" is used to refer to wire or yarn.

[0030] The term "wire" is used to refer to a long, thin component consisting of a single filament. Therefore, the term "single filament" is also used to refer to "wire".

[0031] The term "yarn" is used to refer to a long, thin element composed of an aggregate of multiple filaments twisted together. Therefore, the term "multiple filaments" is also used to refer to "yarn".

[0032] Each filament can also be called a "fiber".

[0033] Therefore, slender elements can be composed of a single wire, a single yarn, or several yarns twisted together.

[0034] In the case of yarns, elongated elements can be identified by abbreviations representing the fabric material, the linear density of the fibers used, and the number of yarns forming the elongated element. For example, an elongated element made of PET (polyethylene terephthalate) identified by PET1672 indicates an elongated element consisting of PET fibers with a linear density of 1670 dtex and formed by two yarns twisted together.

[0035] The term "strand" is used to refer to an assembly consisting of at least two elongated elements. The strand itself may define a reinforcing cord, or it may be intended to be twisted to at least another elongated element or at least another strand to create a reinforcing cord.

[0036] The term "hybrid strand" is used to refer to a strand consisting of at least two slender elements made of different materials.

[0037] In this specification and the following claims, any reference to a particular plastic material should be understood to extend both to fossil-derived plastic materials and, if any, to corresponding recycled or bio-based materials. Thus, for example, when PET is mentioned, it is anticipated that such PET may be of fossil or recycled origin.

[0038] The term “recycled material” is used to refer to a plastic material obtained from waste or industrial waste products made from the corresponding plastic material (usually, but not necessarily of fossil origin) and subjected to appropriate mechanical and / or chemical and / or thermal treatment to enable the production of reusable products.

[0039] The term "non-recycled material" is used to refer to plastic materials derived from fossils.

[0040] The term "bio-based material" is used to refer to materials that are not of fossil origin and are not derived from waste or industrial waste products, but are derived from renewable sources such as, for example, agricultural and forestry products grown and / or used by humans but not for human or animal nutrition.

[0041] The term "diameter" in wire refers to the diameter measured according to the BISFA E10 method (International Bureau for Standardization of Man-made Fibers, Internationally Recognized Test Method for Steel Cord in Tires, 1995).

[0042] The “diameter” of a yarn is intended to represent the diameter of the ideal circumference of all the filaments that circumferentially define the yarn.

[0043] The term "breaking load" for reinforcing cord is used to describe the load at which a reinforcing cord breaks, as assessed according to the BISFA (International Bureau for Standardization of Man-made Fibers) standards relating to the test material as defined herein.

[0044] The term "partial load elongation" for reinforcing cords is used to express the difference between the percentage elongation obtained when the reinforcing cord is subjected to a traction force of 50 N and the percentage elongation obtained when the reinforcing cord is subjected to a traction force of 2.5 N. Partial load elongation is evaluated using the BISFA E7 method (International Bureau for Standardization of Man-Made Fibers, Internationally Recognized Test Method for Steel Cords in Tires, 1995).

[0045] The term "modulus" is used to represent the ratio between load (or force) and elongation measured at any point on a load-elongation curve according to BISFA standards. This curve is plotted by calculating the first derivative of the load-elongation function that defines the curve, which is normalized to a linear density in TeX. Therefore, the modulus is expressed as cN / Tex or MPa. In a load-elongation curve plot, the modulus is identified by the slope of the curve relative to the X-axis.

[0046] The term "initial modulus" is used to refer to the modulus calculated at the origin of the load-elongation curve (i.e., when the elongation is zero).

[0047] The term "final modulus" is used to refer to the modulus calculated near the breaking load, before any sudden failure occurs.

[0048] In the context of this invention, the term "high modulus" is used to refer to a modulus above 5 MPa, while the term "low modulus" is used to refer to a modulus below 5 MPa.

[0049] The term "linear density" or "count" for yarn is used to indicate the weight of a cord / slender element per unit length. Linear density can be measured in dtex (grams per 10 kilometers of length).

[0050] For the measurement of linear density and the determination of tensile properties (such as breaking load), according to the tests specified in the BISFA standard, flat yarn refers to yarn that has not been twisted during the testing phase. Specifically:

[0051] - For aramid fibers (AR), refer to the test methods for aramid fiber yarns - 2002 edition.

[0052] • Determination of linear density - Chapter 6;

[0053] • Determination of tensile properties - Chapter 7 - Test procedures - Section 7.5 - Using the initial pre-stretching procedure;

[0054] - For nylon (NY), refer to BISFA - Test Methods for Polyamide Yarns - 2004 Edition.

[0055] • Determination of linear density - Chapter 6 - Procedure A;

[0056] • Determination of tensile properties - Chapter 7 - Procedure A;

[0057] • Preparation of laboratory samples: Preparation of relaxed samples - Section 7.4.1.1 => Preparation of samples on foldable spools;

[0058] • Preparation of laboratory samples and execution of tests: manual testing - Section 7.5.2.1 => c);

[0059] • Program start => e) Pre-stretch at the start of the program;

[0060] • Use the Zwick-Roell Z010 force gauge to implement traction;

[0061] - For polyester (PET), refer to BISFA - Test Methods for Polyester Yarn - 2004 Edition:

[0062] • Determination of linear density - Chapter 6 - Procedure A;

[0063] • Determination of tensile properties - Chapter 7 - Procedure A;

[0064] • Preparation of laboratory samples: Preparation of relaxed samples - Section 7.4.1.1 => Preparation of samples on foldable spools;

[0065] • Preparation of laboratory samples and execution of tests: manual testing - Section 7.5.2.1 => c);

[0066] • Start Program => e) Pre-stretch at the start of the program;

[0067] • Use the Zwick-Roell Z010 force gauge to implement traction.

[0068] In the following text, when referring to the adhesion to the elastomeric material of the reinforcing cord or its elongated element, reference is made to the adhesive ability of the reinforcing cord / elongated element solely by its shape or structure, and therefore surface coating treatments by adhesive compositions, such as, for example, resorcinol-formaldehyde-latex (RFL) compositions commonly used in the tire manufacturing industry.

[0069] The term "structural component" for tire is used to refer to any tire ply or layer containing reinforcing cords, such as, for example, the carcass ply of a car or motorcycle tire, or the belt ply of a car tire, or the zero-degree reinforcement ply (or cross-belt structure) of a motorcycle tire, or a reinforcing layer associated with the carcass ply of a car tire, said reinforcing layer being located at or near the corresponding folded-up edge of the carcass ply and is also referred to below by the terms "flipper" and "chafer".

[0070] The term "mechanical behavior" of a reinforcing cord or its elongated elements or strip elements incorporating the reinforcing cord is used to describe the response of the reinforcing cord / strip element when subjected to a load (or force). In the case of a traction load, such a load causes an elongation that is a function identified by a specific load-elongation curve and is dependent on the amount of load.

[0071] A tire for a vehicle wheel includes a carcass structure comprising a plurality of reinforcing cords (typically fabric). These reinforcing cords may be incorporated into a single carcass ply or into a plurality of carcass plies (preferably no more than two layers) stacked radially together.

[0072] The tire carcass structure has: a crown portion extending on opposite sides relative to the equatorial plane, wherein reinforcing cords extend in a generally axial direction at the crown portion; and two side portions extending on opposite sides relative to the crown portion, each of the side portions being close to a corresponding sidewall of the tire.

[0073] A crown structure including a belt structure is provided at a radially outer position relative to the tire body structure, and a tread belt made of an elastomeric material is provided at a radially outer position relative to the belt structure.

[0074] The belt structure may include a cross belt structure and / or a zero-degree reinforcement layer.

[0075] A cross-belt structure typically found in automobile tires comprises several radially overlapping belt layers. Specifically, it may provide a first belt layer and at least one second belt layer. The first belt layer comprises reinforcing cords (typically fabric or metal reinforcing cords) that are substantially parallel to each other and inclined at a predetermined angle relative to the tire equator. The second belt layer is arranged radially outward relative to the first belt layer and comprises reinforcing cords (typically fabric or metal reinforcing cords) that are substantially parallel to each other but oriented with an inclination relative to the tire equator opposite to that of the reinforcing cords of the first belt layer.

[0076] The "zero-degree reinforcement layer" comprises multiple fabric reinforcement cords arranged in a generally circumferential winding direction on the belt structure (in the case of automobile tires) or on the crown portion of the tire carcass structure (in the case of motorcycle tires). In motorcycle tires, the zero-degree reinforcement layer itself may define the "belt structure" of the tire, or it may be replaced by two overlapping reinforcement layers defining a cross belt structure.

[0077] Typically, the reinforcing cords of the zero-degree reinforcement layer are incorporated into strip elements of rubberized fabric. These strip elements are spirally wound from one end to the other on the crown portion of the tire carcass structure with a predetermined laying tension.

[0078] The production cycle of tires for vehicle wheels typically begins with a process of building a raw tire, in which the various structural components of the tire are built and assembled. The raw tire thus formed then undergoes molding and vulcanization processes designed to define the structure of the finished tire according to the desired geometry and tread design.

[0079] Typically, the various structural components of a tire are built and assembled on specialized forming drums with a basic cylindrical shape. These forming drums can contract / expand radially.

[0080] Specifically, the body structure is constructed on the first forming drum, which is called the first stage drum, while the crown structure is constructed on the second forming drum, which is called the auxiliary drum or the second stage drum.

[0081] The assembly of the carcass structure and the crown structure can be performed on a first forming drum, in which case the first stage drum is referred to as a single-stage drum or "one-stage" drum. The assembly of the carcass structure and the crown structure can also be performed on different forming drums, referred to as forming drums. This assembly involves shaping the green tire by radially expanding the first stage drum and / or the forming drum after positioning the crown structure coaxially aligned and radially outward relative to the carcass structure. This shaping allows the radially outer surface of the carcass structure to align with the radially inner surface of the crown structure and gives the green tire a toroidal configuration.

[0082] The applicant has observed that during the forming of a green tire, the elongation of the reinforcing cords in the zero-degree reinforcing layer located at the axial center portion of the drum (hereinafter referred to as the "center") is greater than that of the reinforcing cords located at the opposite shoulder portion of the drum (hereinafter referred to as the "shoulder"). In other words, during the forming of a green tire, the strip element incorporating the aforementioned reinforcing cords exhibits greater elongation at the portion around the center of the drum (hereinafter referred to as the "center portion" of the strip element), and less elongation at the opposite side portion around the shoulder of the drum (hereinafter referred to as the "shoulder portion" of the strip element).

[0083] Therefore, at the end of molding, the strip element is stretched more at its central portion and thus has greater stiffness, while it is stretched less at its relative shoulder portion and thus has less stiffness. In particular, the applicant has found that the difference in elongation and therefore stiffness between the central and shoulder portions of the strip element is about 2%-3%.

[0084] The applicant has observed that, on the contrary, it is desirable for the strip element to have substantially uniform stiffness in the axial direction at the end of molding in order to avoid undesirable mechanical behavior inhomogeneity in the zero-degree reinforcement layer in the axial direction at the tire contact area.

[0085] The applicant believes that a suitable measure to limit the aforementioned elongation or stiffness differences and thus shift towards a desired uniformity of stiffness in the axial direction is to wrap the strip element around the drum with a laying tension that varies between the shoulder and center of the drum. Specifically, there may be a greater laying tension at the shoulder of the drum and a smaller laying tension at the center. Thus, at the end of the strip element's laying on the drum and before the forming of the green tire, the strip element is pulled more and therefore stiffer at the shoulder of the drum, and less and therefore stiffer at the center.

[0086] However, the applicant has discovered that the fabric-reinforced cords currently used in tire strip elements on the market have limited elongation under low loads (such as the loads borne by the strip element due to the aforementioned laying tension). Therefore, applying a smaller laying tension at the center of the drum and a larger laying tension at the shoulder of the drum allows only a partial reduction of the stiffness difference that typically exists between the center and shoulder portions of the strip element at the end of molding.

[0087] Therefore, the applicant conceived of manufacturing reinforcing cords with high partial load elongation so that when the strip element is wound onto the drum using a laying tension that is greater at the shoulder of the drum and smaller at the center of the drum, a significantly larger elongation at the shoulder portion of the strip element can be achieved. In this way, before forming the green tire, the strip element is stretched to a greater extent at its shoulder portion (and therefore with greater stiffness) and to a lesser extent at its center portion (and therefore with less stiffness), thereby compensating for the unavoidable difference in elongation along the axial direction that occurs during green tire forming. Therefore, at the end of green tire forming, the desired uniformity of stiffness of the strip element along the axial direction can be achieved.

[0088] In order to reduce the rolling resistance of its tires and thus reduce carbon dioxide emissions into the atmosphere, the applicant is committed to manufacturing the lightest possible reinforcing cords and therefore decided to use slender elements made of non-metallic materials.

[0089] The applicant has recognized that lightweight reinforced cords with high partial load elongation can be obtained by incorporating blank spaces within the reinforcing cord and at least one elongated element made of a non-metallic material and spirally arranged around the blank space. When the reinforcing cord is pulled, the blank spaces allow the helical structure defined by one or more elongated elements of non-metallic material to stretch, thereby achieving a significant elongation of the reinforcing cord.

[0090] To achieve the aforementioned geometry, the applicant envisions using a sacrificial elongated element, around which at least one elongated element made of a non-metallic material is spirally wound, followed by the removal of the sacrificial elongated element. After removal, the at least one elongated element made of the non-metallic material is spirally arranged around the empty space previously occupied by the sacrificial elongated element. Therefore, the sacrificial elongated element serves as a support for at least one elongated element of the reinforcing cord during manufacturing, while simultaneously defining an empty space within the reinforcing cord after its removal.

[0091] Before or after removing sacrificial elongated elements, the blank spaces in the reinforcing cord are maintained by performing a routine adhesion treatment on the reinforcing cord.

[0092] Therefore, in a first aspect of the invention, the present invention relates to a reinforcing cord for a tire used in a vehicle wheel, the reinforcing cord comprising at least two elongated elements made of a non-metallic material.

[0093] Preferably, at least one of the at least two elongated elements is a first elongated element that extends along a helical path around the blank space with a predetermined pitch.

[0094] Therefore, the reinforcing cord of the present invention has a blank space in its radial interior or core portion, and at least two elongated elements in its radial exterior or crown portion.

[0095] The blank space does not necessarily exist in all cross sections of the reinforcing cord, but only needs to exist in multiple cross sections distributed along the entire longitudinal extension of the reinforcing cord.

[0096] In a second aspect, the present invention relates to a method for manufacturing reinforcing cords for tires used in vehicle wheels.

[0097] Preferably, at least one semi-finished product is provided.

[0098] Preferably, the semi-finished product includes at least one sacrificial elongated element.

[0099] Preferably, the semi-finished product includes at least two elongated elements made of non-metallic material.

[0100] Preferably, at least one of the at least two elongated elements, a first elongated element, extends along a helical path with a predetermined pitch around at least one sacrificial elongated element.

[0101] Preferably, at least one sacrificial elongated element is removed from at least one semi-finished product.

[0102] Preferably, after removing at least one sacrificial elongated element, a reinforcing cord is obtained, the reinforcing cord having a blank space previously occupied by the at least one sacrificial elongated element at a radially inward position relative to the at least one first elongated element.

[0103] Preferably, the at least one first elongated element extends along a helical path around the empty space with the predetermined pitch.

[0104] Because the area occupied by the empty space in the reinforcing cord after removing the sacrificial elongated element is not necessarily equal to the area previously occupied by the sacrificial elongated element in its actual cross-section. For example, if the elongated elements defining the reinforcing cord shift relative to each other after removing the sacrificial elongated element, the area occupied by the empty space in the opposite cross-section of the reinforcing cord can be smaller than the area previously occupied by the sacrificial elongated element. However, this area size allows the reinforcing cord to stretch significantly under traction, thereby achieving a high partial load elongation.

[0105] In another aspect of the invention, the invention relates to a tire for a vehicle wheel, the tire comprising a plurality of cords according to a first aspect of the invention.

[0106] According to the applicant, the reinforcing cord of the present invention allows for the achievement of desired stiffness uniformity of the strip element in the axial direction at the end of the forming of a green tire. This is due to the fact that when the strip element is wound around the drum with a larger laying tension at the shoulder of the drum and a smaller tension at the center of the drum, the shoulder portion of the strip element can elongate significantly, resulting in a greater degree of tension and stiffness than the center portion of the strip element, thus compensating for the greater elongation / tension of the center portion of the strip element relative to the shoulder portion during the forming of the green tire.

[0107] Before the tire is formed, the increased stiffness of the shoulder portion of the strip element increases the stiffness of the entire tire crown, thus enabling uniform and effective force transmission between the tire and the road surface at the tire contact patch, which is beneficial to tire performance and rolling resistance.

[0108] The blank spaces also allow the elastomer material to penetrate fully into the reinforcing cord, which is beneficial for the adhesion between the cord and the elastomer material.

[0109] Elastomer materials existing in the empty spaces often also serve as structural components for reinforcing cords, and thus help to make the reinforcing cords more rigid, thereby benefiting tire performance.

[0110] Furthermore, the high partial load elongation of the reinforcing cords of the present invention allows the strip elements combined with these reinforcing cords to withstand high tensile forces during the forming of raw tires, thereby making it possible to lay the strip elements on drums with a diameter smaller than that of drums typically provided, without the risk of breakage of the belt structure with the strip elements wrapped around it.

[0111] The applicant has observed that, depending on the type of elongated elements (wires, yarns, and / or any combination of one or more wires and one or more yarns) used in the reinforcing cord and the type of non-metallic material (low-modulus material, high-modulus material, or any combination of these materials), it is possible to manufacture reinforcing cords according to the invention with properties such that they are suitable for structural components of automobile and motorcycle tires in addition to zero-degree reinforcing layers. In particular:

[0112] - Given the same material and diameter, wire is better suited than yarn to withstand compressive stress and reduce the hysteresis effect caused by friction between wire and / or yarn filaments, while yarn is better suited than wire to withstand bending stress and to bond with surrounding elastomeric materials.

[0113] - For slender elements of the same type and diameter, high modulus materials allow for increased stiffness and / or breaking load, while low modulus materials allow for maximum partial load elongation and / or breaking elongation.

[0114] According to the applicant, when the reinforcing cord of the present invention is used in the cross-belt structure of a tire or the reinforcing structure of the bead (hereinafter referred to as "bead wrapping" and "bead wrapping") or the tire carcass structure, it is preferable to maximize stiffness and / or breaking load, and when the reinforcing cord of the present invention is used in the zero-degree reinforcement layer, it is preferable to maximize partial load elongation and / or breaking elongation.

[0115] In at least one of the foregoing aspects, the present invention may have at least one of the following preferred features.

[0116] Preferably, in at least some cross-sections of the reinforcing cord, the area occupied by the blank space is greater than or equal to 0.018 mm. 2 .

[0117] The applicant believes that, in this case, all the above benefits and advantages can be realized more clearly and effectively, assuming all other parameters are the same.

[0118] Preferably, in all cross-sections of the reinforcing cord, the area occupied by the blank space is greater than or equal to 0.018 mm².

[0119] The applicant has discovered that, in this case, the aforementioned benefits and advantages are maximized.

[0120] Preferably, the predetermined pitch is greater than 2 mm, more preferably greater than 3 mm, and even more preferably greater than 4 mm.

[0121] Preferably, the predetermined pitch is less than 25 mm, more preferably less than 20 mm, and even more preferably less than 12.5 mm.

[0122] In a preferred embodiment, the predetermined pitch is between 2 mm and 25 mm, preferably between 3 mm and 20 mm, and even more preferably between 4 mm and 12.5 mm.

[0123] The applicant has discovered that, under these conditions, with other parameters remaining the same, the partial load elongation and breaking elongation of the reinforcing cord can be maximized. In particular, considering that if the pitch decreases, the diameter of the sacrificial elongated element and the area occupied by the resulting blank space may increase, it is preferable to keep the pitch within the aforementioned range.

[0124] Preferably, at least one of the at least two elongated elements extends around the blank space along its respective helical path with its respective pitch. This measure helps to increase the partial load elongation and breaking elongation of the reinforcing cord, as well as increase the penetration of the elastomer material and its adhesion to the elastomer material.

[0125] The respective pitches may be equal to or different from the predetermined pitch.

[0126] Preferably, the respective pitches are equal to the predetermined pitch.

[0127] In a preferred embodiment, the at least one second elongated element is twisted to at least one first elongated element. In this case, the at least two elongated elements define at least one first strand.

[0128] In a preferred embodiment, the at least one first elongated element is defined by at least one yarn, and the at least one second elongated element is defined by at least one thread. In this way, the typical advantages of both yarn and thread are achieved simultaneously.

[0129] In some preferred embodiments, the reinforcing cord comprises a single first strand.

[0130] Preferably, the single first strand comprises a single strand twisted into a single yarn.

[0131] In other preferred embodiments, the reinforcing cord comprises two first strands twisted together and extending around a blank space along their respective helical paths with their respective pitches.

[0132] The two first-line stocks may be the same as each other or different from each other.

[0133] Preferably, the two first-line strands are identical to each other.

[0134] The respective pitches may be equal to or different from the predetermined pitch.

[0135] Preferably, the respective pitches are equal to the predetermined pitch.

[0136] Preferably, each of the two first strands comprises at least one corresponding thread twisted to at least one corresponding yarn.

[0137] More preferably, each of the two first strands comprises a single strand twisted into a single yarn.

[0138] In some embodiments, the at least one first elongated element and the at least one second elongated element are both made of the same non-metallic material.

[0139] In this case, preferably, the at least two elongated elements are defined by at least one wire and at least one yarn, or by at least two wires with the same or different diameters, or by corresponding yarns with the same or different linear densities.

[0140] In a preferred embodiment, the at least one first elongated element is made of a first non-metallic material, and the at least one second elongated element is made of a second non-metallic material different from the first material. In this case, the at least two elongated elements define at least one first hybrid strand when twisted together.

[0141] In a preferred embodiment, the first material and the second material are selected from: nylon, rayon, PET, aramid, and glass fiber.

[0142] Preferably, the first material is selected from nylon, rayon, PET, aramid, and glass fiber.

[0143] Preferably, the second material is selected from nylon, rayon, and PET.

[0144] Preferably, one elongated element is made of a low-modulus material, while the other elongated element is made of a material with a modulus higher than that of the other elongated elements.

[0145] Preferably, one elongated element is made of a low-modulus material, while the other elongated element is made of a high-modulus material, so as to achieve high stiffness under higher loads in addition to the desired partial load elongation.

[0146] This yields the typical characteristic "bimodulus" mechanical behavior of hybrid reinforced cords, which, in the load-elongation curve, is transformed into a curve defined by two segments separated by a connecting inflection point. In this curve, the segment to the left of the inflection point (representing partial load elongation, which is particularly high in the reinforced cords of this invention) has a much smaller inclination relative to the horizontal axis than the segment to the right of the inflection point (representing stiffness). Under low loads, the mechanical properties of the reinforced cord are primarily determined by the response provided by the low-modulus material (and by the blank space); while under high loads, the mechanical properties of the reinforced cord are primarily determined by the response provided by the high-modulus material.

[0147] Preferably, the at least one first elongated element is defined by at least one aramid or glass fiber or PET yarn, and the at least one second elongated element is defined by at least one nylon or rayon or PET thread.

[0148] In some specific embodiments, at least one first elongated element and at least one second elongated element are both defined by nylon yarn. In this case, a greater partial load elongation is achieved relative to a conventional reinforcing cord defined by two nylon elongated elements, solely due to the presence of blank spaces.

[0149] In some specific embodiments, at least one first elongated element and / or at least one second elongated element are both defined by PET wire or yarn. In these cases, the reinforced cord has greater stiffness than conventional reinforced cords defined by nylon elongated elements because the provision of blank spaces enables partial load elongation, and because at least one of the two elongated elements is made of PET.

[0150] In all the foregoing embodiments described above, the reinforcing cord comprises a plurality of generally circular cross-sections.

[0151] In this case, at least two elongated elements may be arranged on opposite sides of the blank space along the diameter in at least some cross sections of the reinforcing cord, or arranged adjacent to each other circumferentially, possibly in substantial contact with each other.

[0152] In some preferred embodiments, the reinforcing cord further includes at least one third elongated element, which is made of a non-metallic material and is arranged at a radially inward position relative to the at least two elongated elements.

[0153] In this case, preferably, the at least two elongated elements extend along their respective helical paths around at least one third elongated element with the predetermined pitch.

[0154] Therefore, the reinforcing cords in these embodiments have blank spaces and at least one third elongated element in their respective radial inner portions or core portions, and at least two elongated elements in their respective radial outer portions or crown portions.

[0155] The at least one third elongated element may be made of a non-metallic material that is the same as or different from the first material.

[0156] Preferably, the at least one third elongated element is made of a non-metallic material different from the first material.

[0157] Preferably, the at least one third elongated element is made of a material selected from nylon, rayon, or PET.

[0158] Preferably, the at least one third elongated element is defined by at least one wire.

[0159] Preferably, the third elongated element is defined by a single wire.

[0160] In some preferred embodiments, the reinforcing cord includes at least one fourth elongated element, which is made of a non-metallic material and is arranged at a radially inward position relative to the at least two elongated elements.

[0161] Therefore, the reinforcing cords of this embodiment have blank spaces, at least one third elongated element and at least one fourth elongated element in their respective radial inner portions or core portions, and at least two elongated elements in their respective radial outer portions or crown portions.

[0162] Preferably, the at least one fourth elongated element is twisted to at least one third elongated element.

[0163] The at least one fourth elongated element may be made of a non-metallic material that is the same as or different from the material of the at least one third elongated element.

[0164] Preferably, the at least one fourth elongated element is made of a non-metallic material different from the non-metallic material of the at least one third elongated element.

[0165] In this case, the at least third elongated element and the at least fourth elongated element define at least one second hybrid strand, which is preferably arranged at a radially inward position relative to the first hybrid strand.

[0166] The second hybrid strand may be the same as or different from the first hybrid strand.

[0167] Preferably, the second hybrid strand is equivalent to the first hybrid strand.

[0168] Preferably, the at least two elongated elements extend along their respective helical paths around at least one fourth elongated element with the predetermined pitch.

[0169] In some preferred embodiments, the reinforcing cord includes a single second hybrid strand.

[0170] Preferably, the single second hybrid strand comprises a single strand twisted into a single yarn.

[0171] Preferably, the at least one fourth elongated element is made of a material selected from nylon, rayon, PET, aramid, and glass fiber.

[0172] Preferably, the at least one fourth elongated element is defined by at least one yarn.

[0173] Preferably, the at least third elongated element is defined by at least one nylon, rayon, or PET thread, and the at least one fourth elongated element is defined by at least one aramid or glass fiber yarn.

[0174] More preferably, the at least one third elongated element is defined by a single nylon, rayon, or PET thread, and the at least one fourth elongated element is defined by a single aramid or glass fiber yarn.

[0175] Preferably, in all embodiments provided with at least one third elongated element and / or at least one fourth elongated element, the reinforcing cord comprises a plurality of cross sections having a generally elliptical shape.

[0176] Preferably, the reinforcing cord has an initial modulus and a final modulus such that the ratio of the final modulus to the initial modulus is greater than or equal to 9.

[0177] Preferably, the ratio of the final modulus to the initial modulus is greater than or equal to 12, even more preferably greater than or equal to 20, and even more preferably greater than or equal to 30.

[0178] Preferably, the diameter of each wire is greater than or equal to 0.10 mm, more preferably greater than or equal to 0.16 mm, and even more preferably greater than or equal to 0.23 mm.

[0179] Preferably, the diameter of each wire is less than or equal to 0.8 mm, more preferably less than or equal to 0.5 mm, and even more preferably less than or equal to 0.35 mm.

[0180] In a preferred embodiment, the diameter of each wire is between 0.10 mm and 0.8 mm, more preferably between 0.16 mm and 0.5 mm, and even more preferably between 0.23 mm and 0.35 mm.

[0181] Preferably, the linear density of each yarn is greater than or equal to 235 dtex, more preferably greater than or equal to 500 dtex, and even more preferably greater than or equal to 940 dtex.

[0182] Preferably, the linear density of each yarn is less than or equal to 3300 dtex, more preferably less than or equal to 2700 dtex, and even more preferably less than or equal to 2200 dtex.

[0183] Preferably, the linear density of each yarn is between 235 dtex and 3300 dtex, more preferably between 500 dtex and 2700 dtex, and even more preferably between 940 dtex and 2200 dtex.

[0184] Preferably, the reinforcing cord extends along a non-linear longitudinal trajectory.

[0185] Preferably, the longitudinal trajectory is substantially wavy. This wavy shape helps to increase the partial load elongation of the reinforcing cord.

[0186] Preferably, the at least one sacrificial elongated element is a yarn made of a synthetic polymer material, more preferably polyvinyl alcohol (PVA) or polyester (PES) yarn. This material is non-toxic, colorless, and odorless, therefore its use poses no risk to personnel operating it or those near it.

[0187] Preferably, the linear density of at least one sacrificial elongated element is greater than or equal to 200 dtex, more preferably greater than or equal to 700 dtex.

[0188] Preferably, the linear density of at least one sacrificial elongated element is less than or equal to 4400 dtex, more preferably less than or equal to 1670 dtex.

[0189] In a preferred embodiment, the line density of at least one sacrificial elongated element is between 200 dtex and 4400 dtex, preferably between 700 dtex and 1670 dtex.

[0190] Preferably, the at least one sacrificial elongated element is obtained by twisting together elongated elements in a number equal to 16 or a multiple of 16 (e.g., 32).

[0191] In some embodiments, the material of the at least one sacrificial elongated element is water-soluble to allow removal of the at least one sacrificial elongated element by a water bath or water jet.

[0192] Preferably, in the semi-finished product, the at least two elongated elements extend along their respective helical paths around at least one sacrificial elongated element with their respective pitches.

[0193] Preferably, the respective pitches are equal to the predetermined pitch.

[0194] In the method for manufacturing the reinforcing cord of the present invention, after at least one semi-finished product is made, it can be wound onto a service roll, and then the semi-finished product is removed from the service roll to remove the sacrificial elongated elements, and thus the reinforcing cord is made.

[0195] Alternatively, at least one semi-finished product can be continuously fed along a predetermined feed direction to remove the sacrificial elongated element, and thus form a reinforcing cord. In this case, the removal of the sacrificial elongated element from at least one semi-finished product is carried out continuously while manufacturing the semi-finished product, and therefore also continuously while manufacturing the reinforcing cord.

[0196] In both of the above cases, the at least one sacrificial elongated element and the at least two elongated elements are fed into the twisting device.

[0197] Preferably, the at least one first elongated element and the at least one sacrificial elongated element are twisted together in the twisting device.

[0198] Preferably, the twisting is performed with a twist pitch equal to the predetermined pitch.

[0199] Preferably, the twisting is performed by winding the at least one elongated element around the sacrificial elongated element such that the at least one sacrificial elongated element is positioned radially inward relative to the at least one first elongated element.

[0200] In some preferred embodiments, the at least two elongated elements are twisted together before being fed into the twisting device.

[0201] In other preferred embodiments, the at least two elongated elements are fed independently to the twisting device and twisted together with the sacrificial elongated elements in the twisting device at the predetermined twist pitch.

[0202] In some preferred embodiments, the at least one sacrificial elongated element, the at least two elongated elements, and the at least one third elongated element are fed into the twisting device.

[0203] In this case, preferably, the at least two elongated elements and the at least one third elongated element are twisted together with the at least one sacrificial elongated element in a twisting device.

[0204] Preferably, the twisting is performed with the predetermined twist pitch.

[0205] Preferably, the twisting is performed by winding the at least two elongated elements around the sacrificial elongated element and the at least one third elongated element such that the at least one sacrificial elongated element and the at least one third elongated element are arranged in a radially inward position relative to the at least two elongated elements.

[0206] In a further preferred embodiment, the at least one sacrificial elongated element, the at least two elongated elements, the at least one third elongated element, and the at least one fourth elongated element are fed into the twisting device.

[0207] In this case, preferably, the at least two elongated elements, the at least one third elongated element, and the at least one fourth elongated element are twisted together with the at least one sacrificial elongated element in a twisting device.

[0208] Preferably, the twisting is performed with the predetermined twist pitch.

[0209] Preferably, the twisting is performed by winding the at least two elongated elements around the sacrificial elongated element, at least one third elongated element, and at least one fourth elongated element such that the at least one sacrificial elongated element, at least one third elongated element, and at least one fourth elongated element are arranged in a radially inward position relative to the at least two elongated elements.

[0210] In some preferred embodiments, the at least one third elongated element and the at least one fourth elongated element are twisted together before being fed into the twisting device.

[0211] Preferably, the at least two elongated elements, the at least one third elongated element, and the at least one fourth elongated element are twisted together with at least one sacrificial elongated element in the twisting device at the predetermined twist pitch, such that in the semi-finished product, at least one sacrificial elongated element is arranged in a radially inward position relative to the at least two elongated elements, the at least one third elongated element, and the at least one fourth elongated element, or at least one sacrificial elongated element is arranged in a radially inward position relative to the at least two elongated elements and in a radially outward position relative to the at least one third elongated element and the at least one fourth elongated element.

[0212] In some preferred embodiments, in order to remove the at least one sacrificial elongated element, the at least one semi-finished product is fed into a machine equipped with a mechanical removal component.

[0213] In another preferred embodiment where the at least one sacrificial elongated element is made of a water-soluble material, in order to remove the at least one sacrificial elongated element, the at least one semi-finished product is immersed in a water bath and / or impacted by a water jet.

[0214] Preferably, after the at least one sacrificial elongated element has been removed, the reinforcing cord is impinged with a jet of compressed air and dried.

[0215] Preferably, after optional drying, the reinforcing cord is wound onto a collection reel and then removed from the collection reel for use in constructing a tire or a structural component thereof.

[0216] Preferably, the reinforcing cord of the present invention is used in the zero-degree reinforcing layer of a tire. Attached Figure Description

[0217] Further features and advantages of the tire of the present invention will become more apparent from the following detailed description of preferred embodiments of the invention with reference to the accompanying drawings. In these drawings:

[0218] - Figure 1 This is a schematic partial half-sectional view of a portion of an embodiment of a tire including the reinforcing cords according to the invention;

[0219] - Figure 2 These are segmented photographs of a first embodiment of the reinforcing cord according to the present invention;

[0220] - Figure 2a yes Figure 2 The reinforcing cord in Figure 2 A schematic cross-sectional view of the section cut at plane AA marked in the middle;

[0221] - Figure 3 These are segmented photographs of a second embodiment of the reinforcing cord according to the present invention;

[0222] - Figure 3a yes Figure 3 The reinforcing cord in Figure 3 A schematic cross-sectional view of the section cut at the marked plane BB;

[0223] - Figure 4 The load-elongation curves of conventional fabric reinforced cords and reinforced cords manufactured according to the present invention are shown.

[0224] - Figure 5This is a schematic diagram of a first embodiment of an apparatus for manufacturing reinforcing cords according to the present invention, the apparatus performing continuous processing;

[0225] - Figure 6a and Figure 6b A second embodiment of an apparatus for manufacturing reinforcing cords according to the present invention is shown, the apparatus performing intermittent processing;

[0226] - Figure 7 This is a photograph of the sacrificial elongated element used in manufacturing the reinforcing cord of the present invention. Detailed Implementation

[0227] For the sake of simplicity, Figure 1 Only a portion of an exemplary embodiment of the tire 100 according to the invention is shown; the remaining portions, not shown, are substantially the same and are arranged symmetrically with respect to the equatorial plane MM of the tire.

[0228] Figure 1 The tire 100 shown is an exemplary embodiment, particularly for a tire used in a four-wheeled vehicle.

[0229] Preferably, tire 100 is an HP or UHP type tire for sport and / or high-performance and ultra-high-performance vehicles. This tire allows speeds above 190 km / h, up to a maximum of over 300 km / h, and has one of the following speed codes according to ETRTO standards (European Tyre and Rim Technology Organization): “T”, “U”, “H”, “V”, “Z”, “W”, “Y”. The tire's section width is equal to or greater than 185 mm, preferably between 195 mm and 385 mm, more preferably between 195 mm and 355 mm, and is designed to be mounted on rims with a diameter equal to or greater than 13 inches, preferably no greater than 24 inches, more preferably between 16 inches and 23 inches.

[0230] Figure 1 In the diagram, "a" represents the axial direction, "c" represents the radial direction, "MM" represents the equatorial plane of tire 100, and "RR" represents the axis of rotation of tire 100.

[0231] The tire 100 includes a carcass structure 101, which in turn includes at least one carcass ply 111.

[0232] In the following description, for the sake of simplicity, reference will be made to an embodiment of a tire 100 comprising a single carcass ply 111. The description also applies to tires comprising more than one carcass ply.

[0233] The axially opposite end edges of the carcass ply 111 engage with corresponding annular anchoring structures 102 (referred to as bead cores), which may be associated with elastomeric filler 104. The region of the tire 100 including the bead core 102 and possibly the elastomeric filler 104 forms an annular reinforcing structure 103 (referred to as a “bead structure”) and is configured to allow the tire 100 to be anchored to a corresponding mounting rim (not shown).

[0234] The carcass ply 111 includes a plurality of reinforcing cords 10', which are coated with an elastomeric material or incorporated into a matrix of a cross-linked elastomeric material.

[0235] The tire carcass structure 101 is radial, that is, the reinforcing cords 10' are arranged on a plane including the axis of rotation RR of the tire 100 and are substantially perpendicular to the equatorial plane MM of the tire 100.

[0236] Each annular reinforcement structure 103 is associated with the carcass structure 101 by folding (or turning up) the opposite end edges of at least one carcass ply 111 around the bead core 102 and possibly the elastomeric filler 104 to form a so-called flange 101a of the carcass structure 101.

[0237] The crown structure is positioned radially outward relative to the carcass structure 101. The crown structure includes a cross-belt structure 106 and a zero-degree reinforcement layer 106c (commonly referred to as "zero-degree belt").

[0238] The cross-belt structure 106 includes at least two belt layers 106a and 106b that overlap radially with each other.

[0239] The belt layers 106a and 106b each include a plurality of reinforcing cords 10'' and 10'''. These reinforcing cords 10'' and 10''' are oriented at an angle relative to the circumferential direction of the tire 100 or the equatorial plane MM of the tire 100, with the angle between 15° and 45°, preferably between 20° and 40°. For example, the angle is equal to 30°.

[0240] The reinforcing cords 10'', 10''' of one belt layer 106a, 106b are parallel to each other and have a cross orientation relative to the reinforcing cords 10''', 10'' of the other belt layer 106b, 106a.

[0241] The zero-degree reinforcement layer 106c includes reinforcing cords oriented in a generally circumferential direction. Therefore, these reinforcing cords form an angle of a few degrees (typically less than 10°, for example, between 0° and 6°) with respect to the equatorial plane MM of the tire 100.

[0242] The tread strip 109, made of elastomeric material, is applied at a radially outer position relative to the zero-degree reinforcement layer 106c.

[0243] A corresponding sidewall 108 made of an elastomeric material is also applied to the side surface of the carcass structure 101 at an axially lateral position relative to the carcass structure 101 itself. Each sidewall 108 extends from one of the side edges of the tread band 109 to the corresponding annular reinforcement structure 103.

[0244] In some specific embodiments, such as those shown and described herein, the stiffness of the sidewall 108 can be increased by providing a reinforcing layer 120 (commonly referred to as a “wire loop overlay” or additional strip insert), the function of which is to increase the stiffness and integrity of the annular reinforcement structure 103 and the sidewall 108.

[0245] The outer wrapping fabric 120 of the steel wire bead is wound around the corresponding bead core 102 and the elastomeric filler 104 to at least partially surround the annular reinforcement structure 103. In particular, the outer wrapping fabric 120 of the steel wire bead wraps around the annular reinforcement structure 103 along the axial inner region, the axial outer region, and the radial inner region of the annular reinforcement structure 103.

[0246] The outer sheath 120 of the steel wire bead is arranged between the raised edge of the carcass ply 111 and the corresponding annular reinforcement structure 103. Typically, the outer sheath 120 of the steel wire bead is in contact with the carcass ply 111 and the annular reinforcement structure 103.

[0247] In some specific embodiments, such as those shown and described herein, the bead structure 103 may also include another reinforcing layer 121 (commonly referred to by the term "bead wrap" or protective strip) and the function of the other reinforcing layer is to increase the stiffness and integrity of the annular reinforcing structure 103.

[0248] The bead wrap 121 is connected to the corresponding folded end edge of the carcass ply 111 at an axially lateral position relative to the corresponding annular reinforcement structure 103 and extends radially toward the sidewall 108 and the tread strip 109.

[0249] The outer sheath 120 of the bead and the outer sheath 121 of the tire include reinforcing cords 10* (in the attached drawings, the reinforcing cords of the outer sheath 120 of the bead are not visible).

[0250] exist Figure 1 In the tire, at least some (preferably all the cords of the zero-degree reinforcement layer 106c) are reinforcement cords 10 according to the invention.

[0251] Figure 2 and Figure 2a A first embodiment of this reinforced cord 10 is shown.

[0252] This reinforcing cord 10 includes two strands 11, each of which includes two elongated elements 11a, 11b made of a non-metallic material.

[0253] Each of the two strands 11, and therefore each of the corresponding elongated elements 11a, 11b, extends longitudinally around the empty space 10a along its respective helical path with a predetermined pitch E. Figure 2 The longitudinal direction L of each elongated element 11a, 11b is indicated, and thus the longitudinal direction L of the two strands 11 is also indicated, as well as the longitudinal direction L of the reinforcing cord 10.

[0254] Preferably, the reinforcing cord 10 extends along the longitudinal direction L in a non-linear (more preferably wavy) trajectory.

[0255] See below for reference Figure 5 , Figure 6a and Figure 6b The reinforcing cord 10 is obtained by combining two strands 11 and a sacrificial elongated element 20 (e.g., ...). Figure 7 The type shown, and in Figure 2a (Indicated by dashed lines) are twisted together with a pitch equal to the pitch E mentioned above to form a semi-finished product 15, so that the sacrificial elongated element 20 is in a radially inward position relative to the two strands 11.

[0256] Before twisting the two strands 11 together with the sacrificial elongated element 20, each of the two strands 11 can be obtained by twisting together the corresponding elongated elements 11a, 11b.

[0257] After the sacrificial elongated element 20 and the two strands 11 have been twisted, the sacrificial elongated element 20 is removed from the semi-finished product 15, thereby leaving a blank space 10a in the reinforcing cord 10. After removal, the two strands 11 retain their helical geometry and define the reinforcing cord 10, which also has a helical geometry.

[0258] like Figure 2a As shown, each cross-section of the reinforcing cord 10 is generally circular and has a blank space 10a in the position previously occupied by the sacrificial elongated element 20 and therefore in a radially inward position relative to the two strands 11. In the particular case shown herein, the two strands 11 are arranged on diametrically opposite sides relative to the blank space 10a.

[0259] The sacrificial elongated element 20 is preferably a yarn made of a synthetic polymer material (preferably a water-soluble polymer material, such as polyvinyl alcohol (PVA) or polyester (PES)). It can be purchased from a specialized manufacturer (such as, for example, Kuraray Co., Ltd or Sekisui Specialty Chemicals), or it can also be made by twisting multiple PVA or PES elongated elements together in a conventional twisting apparatus.

[0260] The pitch E ranges from 2 mm to 25 mm, preferably from 3 mm to 20 mm, and more preferably from 4 mm to 12.5 mm.

[0261] The linear density of the sacrificial elongated element 20 is between 200 dtex and 4400 dtex, preferably between 700 dtex and 1670 dtex.

[0262] The diameter and / or linear density of the sacrificial elongated element 20 and the pitch E are selected such that the area occupied by the blank space 10a in at least some cross sections (preferably all cross sections) of the reinforcing cord 10 is greater than or equal to 0.018 mm². In this case, the diameter of the sacrificial elongated element 20 is greater than or equal to about 0.15 mm.

[0263] exist Figure 2 and Figure 2a In the embodiment of the reinforcing cord 10 shown, each of the two elongated elements 11a is defined by a corresponding yarn, while each of the two elongated elements 11b is defined by a corresponding wire.

[0264] The diameter of each wire is between 0.10 mm and 0.8 mm, preferably between 0.16 mm and 0.5 mm, and more preferably between 0.23 mm and 0.35 mm.

[0265] The linear density of each yarn is between 235 dtex and 3300 dtex, preferably between 500 dtex and 2700 dtex, and more preferably between 940 dtex and 2200 dtex.

[0266] Each wire is made from materials selected from nylon, rayon, and PET.

[0267] Each yarn is made from materials selected from nylon, rayon, PET, aramid, and glass fiber.

[0268] Preferably, each wire is made of a low-modulus material, particularly nylon, rayon, or PET, and each yarn is made of a high-modulus material, particularly aramid or glass fiber.

[0269] In cases where each thread is made of nylon, rayon, or PET, each yarn can be made of PET.

[0270] refer to Figure 5 It describes the manufacturing process. Figure 2 Exemplary embodiments of the apparatus and method for enhancing the cord 10.

[0271] The sacrificial elongated element 20 (water-soluble in this example) and the two strands 11 are removed from the corresponding spools 40 and 30 and fed into the twisting device 60 for mutual twisting to form a semi-finished product 15. The twisting device 60 is therefore relative to... Figure 5 The feed direction, indicated by A, is located downstream of spools 40 and 30. The twisting of the sacrificial elongated element 20 and the two strands 11 is performed by winding the two strands 11 around the sacrificial elongated element 20 such that the sacrificial elongated element 20 is positioned radially inward relative to the two strands 11.

[0272] The semi-finished product 15 is fed along the feed direction A to the removal device 70, where sacrificial elongated elements 20 are removed from the semi-finished product 15 to form the reinforcing cord 10. Therefore, the removal device 70 is arranged downstream of the twisting device 60 relative to the feed direction A.

[0273] In one embodiment of the invention, the removal device 70 includes a tank 73 in which the semi-finished product 15 is impacted by a jet of hot water flowing in the opposite direction while moving along the feed direction A. The hot water jet dissolves the sacrificial elongated element 20, while the strand 11 passes through the jet, making the strand the sole component of the reinforcing cord 10.

[0274] Preferably, the reinforcing cord 10 thus formed then travels through the compressed air supply and drying device 75 to subsequently wind onto a corresponding collection drum 50 from which the reinforcing cord can be removed during tire 100 construction. Therefore, the compressed air supply and drying device 75 is arranged downstream of the removal device 70 relative to the feed direction A.

[0275] In the above reference Figure 5 In the described process, the reinforcing cord 10 is continuously manufactured simultaneously with the production of the semi-finished product 15 (and thus the reinforcing cord 10 is also continuously manufactured during the removal of the sacrificial elongated element 20). The reinforcing cord 10 is then manufactured by a continuous process that, in chronological order, includes: forming the semi-finished product 15 by twisting the strands 11 and the sacrificial elongated element 20 together; moving the thus formed semi-finished product 15 along the feed direction A; removing the sacrificial elongated element 20; drying the thus formed reinforcing cord 10; and winding the reinforcing cord 10 onto the collection spool 50.

[0276] However, the reinforcing cord 10 can also be made through two different operating steps (i.e., through intermittent processing), such as, for example, Figure 6a and Figure 6b The process shown is the same as described in the reference above. Figure 5 The only difference in the described process is that, once the semi-finished product 15 is made, it is collected into the service roll 45. Figure 6a When it is desired to proceed with the manufacturing of the previously described reinforcing cord 10, the semi-finished product can be removed from the service drum 45. Figure 6b Therefore, the service roll 45 is intended to be positioned downstream of the twisting device 60 when manufacturing the semi-finished product 15, and upstream of the removal device 70 when removing the sacrificial elongated element 20 from the semi-finished product 15 to manufacture the reinforcing cord 10.

[0277] Alternatively, sacrificial elongated elements 20 can be removed from the semi-finished product 15 by feeding it into a machine equipped with mechanical removal components. These mechanical removal components remove the sacrificial elongated elements 20 while maintaining their integrity, allowing them to be reused for other purposes.

[0278] Before or after the removal of the sacrificial elongated element 20, the reinforcing cord 10 undergoes a conventional adhesion treatment that allows the geometry of the reinforcing cord 10 to be stabilized while maintaining the aforementioned blank space 10a in the reinforcing cord 10.

[0279] The reinforcing cord 10 is intended to be incorporated into a strip-shaped element made of an elastomeric material and is intended to be used in the manufacture of the zero-degree reinforcing layer 106c of the tire 100.

[0280] Figure 2 and Figure 2a A first example of the reinforcing cord 10 of the type shown has the following construction:

[0281] (32)+2×(AR1680+NY0.28)4.3

[0282] Moving from left to right:

[0283] - The number in parentheses indicates the number of elongated elements made of PVA and twisted together to obtain the sacrificial elongated elements 20 that will be removed later (32 elongated elements in this particular case).

[0284] - The number after the "+" sign indicates the number of strands 11 twisted into the sacrificial elongated element 20 (2 strands in this particular case).

[0285] - The content in parentheses after the "×" sign indicates the composition of each strand 11, which specifies the material and linear density of the yarn and the material and diameter of the thread (in this particular case, each strand 11 is a hybrid strand, which includes aramid yarn with a linear density of 1680 dtex and nylon thread with a diameter of 0.28 mm).

[0286] -4.3 is the pitch E of the 11-strand thread.

[0287] In this example, two strands 11 extend along corresponding helical paths at pitch E at the crown portion of the reinforcing cord 10, while blank space 10a is arranged at the core portion of the reinforcing cord 10.

[0288] Figure 2 and Figure 2a Another example of the reinforcing cord 10 of the type shown has the following construction:

[0289] (32)+2×(AR1680+PET0.16)4.3.

[0290] The only difference between this reinforcing cord 10 and the reinforcing cord of the first example is that, in each strand 11, in addition to the aramid yarn, there is a PET thread with a diameter of 0.16 mm, instead of a nylon thread with a diameter of 0.33 mm.

[0291] A method according to the present invention and constructed with Figure 2 and 2a Examples of reinforcing cords with different constructions, not shown, have the following constructions:

[0292] (32)+1×(AR1680+NY0.33)4.3.

[0293] The only difference between this reinforced cord and the reinforced cord in the first example is that it provides only a single strand, which, in addition to the aramid yarn, also includes nylon thread with a diameter of 0.33 mm. It can be used in conjunction with the above reference. Figure 2 and Figure 2a The reinforcing cord is manufactured using a similar process to that used for reinforcing cords, for example, by using... Figure 5 , Figure 6a and Figure 6b The process described and shown is similar to that used to manufacture this reinforced cord. However, in this case, in addition to the sacrificial elongated elements (from the drum 40), individual strands 11 (from the corresponding drum 30) are also fed to the twisting device 60.

[0294] Figure 3 and Figure 3a Another example of the reinforcing cord 10 according to the invention is shown.

[0295] This reinforced cord 10 and Figure 2 and Figure 2a The difference in the reinforcing cord shown is that, in addition to the two strands 11 and the blanking space 10a described above, it also includes two elongated elements 11c made of non-metallic material and arranged in a radially inward position. Furthermore, in this reinforcing cord 10, the two strands 11 extend along their respective helical paths at a pitch E at the crown portion of the reinforcing cord 10. However, in this case, the reinforcing cord 10 includes, in its core portion, the blanking space 10a previously occupied by the sacrificial elongated elements 20 (in... Figure 3a (represented by dashed lines) and two slender elements 11c.

[0296] In this case, such as Figure 3a As shown, each cross-section of the reinforcing cord 10 has a generally elliptical shape.

[0297] exist Figure 3 and Figure 3a In the specific example shown, two strands 11 are arranged adjacent to each other in the circumferential direction around two elongated elements 11c and the blank space 10a.

[0298] exist Figure 3 and Figure 3a In the embodiment of the reinforcing cord 10 shown, each of the two elongated elements 11c is defined by a corresponding wire with a diameter between 0.10 mm and 0.8 mm, preferably between 0.16 mm and 0.5 mm, and more preferably between 0.23 mm and 0.35 mm.

[0299] Each of the wires is made of a material selected from nylon, rayon, and PET.

[0300] Figure 3 and Figure 3a The example of the reinforcing cord 10 of the type shown has the following construction:

[0301] (32)+2×NY0.23+2×(AR1680+NY0.23)5.3,

[0302] Two of the wires, 11c, are made of nylon and have a diameter of 0.23 mm.

[0303] Figure 3 and Figure 3a The reinforcing cord shown can be made from the reference above. Figure 2 and Figure 2a The reinforcing cord is manufactured using a similar process to that described above, for example, with... Figure 5 , Figure 6a and Figure 6bThe manufacturing process is similar to that described and shown in the text. However, in this case, in addition to the spools 40 and 30 shown, two additional spools are provided for feeding the elongated element 11c to the twisting device 60.

[0304] Figure 3 and Figure 3a Another example of the reinforcing cord 10 of the type shown differs from the example above only in that the cord 11c is made of PET instead of nylon, and / or is provided as a single cord 11c of nylon or PET instead of two cords 11c; and / or is provided as a single strand 11 instead of two strands 11.

[0305] The invention and its construction are described below. Figure 2 and Figure 2a as well as Figure 3 and Figure 3a Another embodiment, not shown, with different constructions of the reinforcing cords.

[0306] In addition to the two strands 11 and the blank space 10a, this reinforcing cord also includes another strand arranged in a radially inward position relative to the two strands 11, the other strand including an elongated element 11c of the above type twisted to another elongated element made of a non-metallic material.

[0307] Therefore, in this case, two strands 11 extend along their respective helical paths at the crown portion of the reinforcing cord 10 around the core portion of the reinforcing cord 10 with a pitch E, the core portion including the blank space 10a previously occupied by the sacrificial elongated element 20 and the other strand.

[0308] In the above-described embodiment of the reinforcing cord, the other elongated element is defined by a yarn with a linear density between 235 dtex and 3300 dtex, preferably between 500 dtex and 2700 dtex, and more preferably between 940 dtex and 2200 dtex.

[0309] The yarn is made from materials selected from nylon, rayon, PET, aramid, and glass fiber.

[0310] The construction example of the above-mentioned reinforcing cord is as follows:

[0311] (32)+(AR1680+NY0.28)+(AR1680+NY0.33)5.3.

[0312] In this specific case, the strands arranged in the core portion of the reinforcing cord comprise aramid yarn with a linear density of 1680 dtex, which is twisted into nylon thread with a diameter of 0.28 mm. The crown portion comprises a single strand, which also comprises aramid yarn with a linear density of 1680 dtex, twisted into nylon thread with a diameter of 0.33 mm.

[0313] This type of reinforcing cord can be made from the above reference. Figure 2 and Figure 2a The reinforcing cords are manufactured using a process similar to that described above, for example, employing a process similar to that described above. Figure 5 , Figure 6a and Figure 6b The process described and shown is similar to that used in the process. However, in this case, in addition to the sacrificial elongated element 20 (supplied from spool 40) and strand 11 (supplied from spool 30), another strand (feed from a spool similar to spool 30) is also fed to the twisting device 60.

[0314] In all reinforcing cords according to the invention, it is preferred to provide at least one elongated element made of a low-modulus material and at least one elongated element made of a high-modulus material. In particular, the ratio of final modulus to initial modulus is greater than or equal to 9.

[0315] The applicant conducted comparative tensile tests on three types of reinforcing cords according to the present invention and conventional reinforcing cords commonly used in zero-degree reinforcement layers of tires, in accordance with BISFA standards.

[0316] The standard reinforcing cord comprises two aramid yarns, each with a linear density of 1330 dtex, twisted to a nylon yarn with a linear density of 1400 dtex. This cord is referred to herein as STD.

[0317] The reinforcing cord according to the present invention has the following structure:

[0318] -(32)+2×(AR1680+NY0.28), here denoted as INV1;

[0319] -(16)+PET0.30+2×(AR1680+NY0.23), here denoted as INV2;

[0320] -(32)+2×NY0.23+2×(AR1680+NY0.23), here denoted as INV3.

[0321] In the three types of reinforcing cords, INV1, INV2, and INV3, the sacrificial elongated elements are made of PVA.

[0322] Figure 4The results of these comparative tests are shown.

[0323] It is worth noting that, with other parameters being equal, the partial load elongation of the reinforced cord according to the present invention is much greater than that of conventional reinforced cords, consistently exceeding 2%, and approaching 8% in the specific case of cord INV3. It is also noteworthy that, due to the use of sacrificial elongated elements (and therefore the resulting empty space after their removal) and the use of both low-modulus and high-modulus elongated elements, the reinforced cord according to the present invention possesses characteristic "bimodulus" mechanical properties, thereby ensuring high full-load stiffness in addition to the desired partial load elongation.

[0324] The present invention has been described with reference to some preferred embodiments. Various modifications can be made to the above embodiments, and these modifications still fall within the protection scope of the present invention as defined by the following claims.

Claims

1. A reinforcing cord (10) for a tire used in a vehicle wheel, said reinforcing cord comprising at least two elongated elements (11a, 11b) made of a non-metallic material, wherein, At least one of the at least two elongated elements (11a, 11b) extends along a helical path around a blank space (10a) with a predetermined pitch (E).

2. The reinforcing cord (10) according to claim 1, wherein, In at least some cross sections of the reinforcing cord (10), the blank space (10a) occupies an area greater than or equal to 0.018 mm².

3. The reinforcing cord (10) according to claim 1 or 2, wherein, At least one of the at least two elongated elements (11a, 11b) extends along its respective helical path around the empty space (10a) with its respective pitch (E).

4. The reinforcing cord (10) according to claim 3, wherein, The at least one first elongated element (11a) is defined by at least one yarn, and the at least one second elongated element (11b) is defined by at least one wire.

5. The reinforcing cord (10) according to claim 3 or 4, wherein, The at least one first elongated element (11a) is made of a non-metallic first material, and the at least one second elongated element (11b) is made of a non-metallic second material different from the first material.

6. The reinforcing cord (10) according to claim 5, wherein, The first material and the second material are selected from: nylon, rayon, PET, aramid, and glass fiber.

7. The reinforcing cord (10) according to any one of the preceding claims, the reinforcing cord further comprising at least one third elongated element (11c), said at least one third elongated element being made of a non-metallic material and arranged in a radially inward position relative to said at least two elongated elements (11a, 11b), wherein, The at least two elongated elements (11a, 11b) extend along their respective helical paths around the at least one third elongated element (11c) at the predetermined pitch (E).

8. The reinforcing cord (10) according to claim 7, wherein, The at least one third elongated element (11c) is made of a material selected from nylon, rayon, and PET.

9. The reinforcing cord (10) according to claim 7 or 8, wherein, The at least one third elongated element (11c) is defined by at least one wire.

10. The reinforcing cord (10) according to any one of the preceding claims, wherein, The reinforcing cord (10) has an initial modulus and a final modulus such that the ratio of the final modulus to the initial modulus is greater than or equal to 9.

11. The reinforcing cord (10) according to any one of the preceding claims, wherein, The reinforcing cord (10) extends along a non-linear longitudinal trajectory.

12. A method for manufacturing reinforcing cords for tires used in vehicle wheels, the method comprising: - Provide at least one semi-finished product (15), the at least one semi-finished product comprising at least one sacrificial elongated element (20) and at least two elongated elements (11a, 11b) made of non-metallic material, wherein at least one of the at least two elongated elements (11a, 11b) extends along a helical path around the at least one sacrificial elongated element (20) with a predetermined pitch (E); - Remove the at least one sacrificial elongated element (20) from the at least one semi-finished product (15) to obtain a reinforcing cord (10) having a blank space (10a) previously occupied by the at least one sacrificial elongated element (20) in a radially inward position relative to the at least one first elongated element (11a), wherein the at least one first elongated element (11a) extends along a helical path around the blank space (10a) with the predetermined pitch (E).

13. The method according to claim 12, wherein, Providing the at least one semi-finished product (15) includes: - The at least one sacrificial elongated element (20) and the at least two elongated elements (11a, 11b) are fed into the twisting device (60). - By winding the at least one first elongated element (11a) around the sacrificial elongated element (20) such that the at least one sacrificial elongated element (20) is arranged in a radially inward position relative to the at least one first elongated element (11a), the at least one first elongated element (11a) and the at least one sacrificial elongated element (20) are twisted together in the twisting device (60) with a twist equal to the predetermined pitch (E).

14. The method according to claim 13, wherein, Providing the at least one semi-finished product (15) includes: - The at least one sacrificial elongated element (20), the at least two elongated elements (11a, 11b) and the at least one third elongated element (11c) are fed into the twisting device (60). - By winding the at least two elongated elements (11a, 11b) around the sacrificial elongated element (20) and the at least one third elongated element (11c), such that the at least one sacrificial elongated element (20) and the at least one third elongated element (11c) are arranged in a radially inward position relative to the at least two elongated elements (11a, 11b), thereby twisting the at least two elongated elements (11a, 11b) and the at least one third elongated element (11c) together with the at least one sacrificial elongated element (20) in the twisting device (60) with the predetermined twist pitch.

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