Double-layer multi-strand cable with improved surface breaking energy

Abstract

The present invention relates to a multi-strand cable (50), comprising an inner cable layer (CI) and an outer cable layer (CE), wherein the inner cable layer (CI) is composed of K=1 inner strands (TI) having three layers (C1, C2, C3), i.e., an inner layer (C1) consisting of Q inner metal wires (F1), a middle layer (C2), and an outer layer (C3) consisting of N outer metal wires (F3), and the outer cable layer (CE) is composed of L>1 outer strands (TE) having two layers (C1', C3') wound around the inner cable layer (CI), i.e., an inner layer (C1') consisting of Q' inner metal wires (FT) and an outer layer (C3') consisting of N' outer metal wires (F3'). The cable (50) has a surface breaking energy ES>175 N.mm-1, ES=(I), where (II) is the sum of the breaking forces of Nc wires, (III) is the sum of the total elongation of Nc wires, Cfrag is the weakening coefficient of the cable (50), and D is the diameter of the cable (50). (I)#imgabs0#(II)#imgabs1#(III)#imgabs2#

Description

Technical Field

[0001] The present invention relates to cords and tires comprising these cords. Background Art

[0002] A tire for construction site vehicles is known from the prior art (in particular document EP 2 426 255 B1), having a radial carcass reinforcement and comprising a tread, two inextensible beads, two sidewalls connecting the beads to the tread, and a crown reinforcement arranged circumferentially between the carcass reinforcement and the tread. This crown reinforcement comprises four plies reinforced with reinforcing elements (for example metal cords), the cords of one ply being embedded in an elastomeric matrix of the ply.

[0003] The crown reinforcement comprises a plurality of working plies comprising a plurality of filamentary reinforcing elements. Each working filamentary reinforcing element is a double-layer multi-strand cord, which has an inner cord layer and an outer cord layer. The inner cord layer is composed of K=1 three-layer internal wire strands, and the three-layer internal wire strands include an inner layer composed of Q=3 internal metal wires with a diameter of d1=0.40 mm, a middle layer composed of M=9 middle metal wires with a diameter of d2=0.40 mm wrapped around the inner layer, and an outer layer composed of N=15 external metal wires with a diameter of d3=0.40 mm wrapped around the middle layer. The outer cord layer is composed of L=8 double-layer external wire strands, and the double-layer external wire strands include an inner layer composed of Q'=3 internal metal wires with a diameter of d1'=0.35 mm and an outer layer composed of N'=9 external metal wires with a diameter of d3'=0.35 mm wrapped around the inner layer. For a breaking force of 36128 N, the diameter of the non-wound cord is equal to 5.27 mm.

[0004] On the one hand, when the tire passes over obstacles (for example in the form of rocks), these obstacles present the risk of puncturing the tire up to the crown reinforcement. These punctures allow corrosive agents to enter the crown reinforcement of the tire and reduce its life.

[0005] On the other hand, it has been found that the cords of the crown ply may exhibit breakage caused by relatively significant deformations and loads applied to the cords, in particular when the tire passes over an obstacle. Summary of the Invention

[0006] A subject of the present invention is a cord making it possible to reduce or even eliminate the number of breaks and the number of punctures.

[0007] For this purpose, a subject of the invention is a double-layer multi-strand cord comprising:

[0008] - an inner layer of cords, said inner layer of cords being composed of K=1 three-layer inner strands, said three-layer inner strands comprising:

[0009] - an inner layer consisting of Q inner metal wires,

[0010] - an intermediate layer consisting of M intermediate metal wires wound around the inner layer, and

[0011] an outer layer consisting of N outer metal wires of diameter d3 wound around the intermediate layer,

[0012] - an outer layer of cords, said outer layer of cords being composed of L>1 double-layer outer strands wound around an inner layer of cords, said double-layer outer strands comprising:

[0013] - an inner layer consisting of Q' = 2, 3 or 4 inner metal wires, and

[0014] - an outer layer consisting of N' outer metal wires with a diameter d3' wound around the inner layer, wherein the breaking energy per unit area of the cord ES ≥ 175 N.mm -1 , in:

[0015] - is the sum of the breaking forces of Nc wires, in Newtons;

[0016] - Nc = Q + M + N + L × (Q' + N') is the total number of metal wires;

[0017] -D is the diameter of the cord, in mm;

[0018] - is the sum of the total elongation of Nc wires and is dimensionless;

[0019] -Cfrag is the dimensionless weakening coefficient of the cord, where

[0020] in:

[0021] d3 and d3' are expressed in mm,

[0022] αf is the contact angle between the outer wire of the inner strand and the outer wire of the outer strand, expressed in radians,

[0023] αt is the helix angle of each external strand (TE), expressed in radians;

[0024] Cste=1500N.mm -2 .

[0025] Due to its relatively high breaking energy per unit area, the cord according to the present invention is able to reduce punctures and thus extend the life of the tire, and is also able to reduce the number of breaks. Specifically, the inventors of the present invention have discovered that the determining criterion for reducing cord breakage lies not only in the breaking force widely taught in the prior art, but also in the breaking energy per unit area, which is expressed in the present application as an indicator equal to the product of the breaking force, elongation at break, and weakening factor of the cord divided by the cord diameter.

[0026] The weakening factor allows for the loss of tensile performance of the cord due to transverse weakening of the inter-wire contact between the layers of outer metal wires in the inner and outer layers to be taken into account. This weakening factor depends on the number of outer metal wires in the inner layer, the contact angle between the inner and outer strands, the diameters d3 and d3' of the outer metal wires of the inner and outer layers, respectively, the helix angle of the outer strands, and the breaking force of the outer strands. Thus, strong cords have a weakening factor close to 1, while weak cords have a suboptimal weakening factor close to 0.5.

[0027] Specifically, the cords of the prior art have a relatively high breaking force but a suboptimal weakening factor (e.g., Example 2 of EP 2426255 B1), or have an optimal weakening factor (i.e., a weakening factor close to 1) but a relatively low breaking force. In both cases, the cords of the prior art have a relatively low breaking energy per unit area. Due to their relatively high weakening factor and their relatively high breaking force, the cords according to the present invention exhibit a relatively high breaking energy per unit area.

[0028] Any numerical range expressed by the expression "between a and b" means a numerical range from greater than a to less than b (i.e., excluding the endpoints a and b), while any numerical range expressed by the expression "from a to b" means a numerical range extending from the endpoint "a" up to the endpoint "b" (i.e., including the strict endpoints "a" and "b").

[0029] By definition, the diameter of a strand is the diameter of the smallest circle within which the strand is circumscribed.

[0030] By definition, the diameter of a cord is the diameter of the smallest circle within which the bare cord is circumscribed.

[0031] In the present invention, the cord has two layers with strands, which means that it comprises an assembly consisting of neither more nor less than two layers with strands, which means that the assembly has two layers with strands, not one layer, not three layers, but only two layers.

[0032] In one embodiment, the inner strands of the cord are surrounded by the polymer compound and then by the outer layer.

[0033] Advantageously, the inner strand has a cylindrical layer.

[0034] Advantageously, each outer strand has a cylindrical layer.

[0035] Advantageously, the inner strand and each outer strand have a cylindrical layer. It should be recalled that such a cylindrical layer is obtained when the various layers of the strand are wound with different lay lengths and / or when the winding direction of these layers varies from one layer to another. Unlike strands with compact layers (in which all layers have the same lay length and all layers are wound in the same direction, thus exhibiting very low permeability), strands with cylindrical layers are extremely highly permeable.

[0036] The inner strand is a three-layer strand. The inner strand comprises a thread aggregate consisting of neither more nor less than three layers with filaments, which means that the thread aggregate has three layers with filaments, not two layers, not four layers, but only three layers.

[0037] The outer strands are double-layered strands. The outer strands comprise a thread assembly consisting of neither more nor less than two layers with threads, which means that the thread assembly has two layers with threads, not one, not three, but only two layers.

[0038] It should be recalled that, as is known, the lay length of a strand represents the length of this strand, measured parallel to the axis of the cord, after which a strand having this lay length completes one full turn around said axis of the cord. Similarly, the lay length of a thread represents the length of this thread, measured parallel to the axis of the strand in which it is located, after which a thread having this lay length completes one full turn around said axis of the strand.

[0039] The winding direction of a layer with strands or a layer with filaments means the direction in which the strands or filaments form relative to the axis of the cord or strand. The winding direction is usually indicated by the letter Z or the letter S.

[0040] Determine the lay length, winding direction and diameter of wires and strands according to the 2014 standard ASTM D2969-04.

[0041] The contact angle between the outer wires of the inner strand and the outer wires of the outer strand is Figure 6Angle αf is shown. This schematic diagram of the cord according to the invention shows the cord axis AA', around which the inner and outer layers are wound. In this figure, only the two metal wires of the outer layer of the outer strand are retained to better illustrate the angle αf, which is the contact angle between the outer metal wires of the inner strand and the outer metal wires of the outer strand. This is one of the relevant parameters for determining the cord's weakening coefficient, as the smaller the contact angle, the less weakening the cord will be.

[0042] The helix angle αt of each outer strand is a parameter well known to those skilled in the art and can be determined using the following calculation formula: tanαt = 2×π×Re / pe, where pe is the lay length of each outer strand in millimeters, re is the helix radius of each outer strand in millimeters, and tan represents the tangent function. αt is expressed in degrees.

[0043] By definition, the helix radius Re of the outer layer of the cord is the radius of a theoretical circle which passes through the centre of the external strands of the outer layer in a plane perpendicular to the axis of the cord.

[0044] The total elongation Δt (a parameter well known to those skilled in the art) is determined, for example, by applying the 2014 ASTM D2969-04 standard to the tested yarn to obtain a force-elongation curve. From the resulting curve, Δt is derived as the elongation in %, which corresponds to the projection of the point on the force-elongation curve where the yarn breaks (i.e., the point where the load increases to a maximum breaking force (Fm) and then drops sharply after breaking) onto the elongation axis. When the decrease relative to Fm exceeds a certain level, this means that the yarn has broken.

[0045] Preferably, the strands are not pre-formed.

[0046] Advantageously, the cord is made of metal. By definition, the term "metal cord" is understood to mean a cord formed from threads made primarily (i.e., greater than 50% of these threads) or entirely (100% of the threads) of a metallic material. This metallic material is preferably steel, more preferably pearlitic (or ferritic-pearlitic) carbon steel, hereinafter referred to as "carbon steel," or stainless steel (by definition, steel containing at least 11% chromium and at least 50% iron). However, other steels or other alloys may also be used.

[0047] When carbon steel is advantageously used, its carbon content (% by weight of steel) is preferably between 0.4% and 1.2%, in particular between 0.5% and 1.1%; these contents represent a good compromise between the mechanical properties required for the tire and the processability of the wire.

[0048] The metal or steel used (whether in particular carbon steel or stainless steel) may itself be coated with a metal layer which, for example, improves the workability of the metal cord and / or its constituent elements or improves the use properties of the cord and / or the tire itself (for example, properties of adhesion, corrosion resistance or aging resistance). According to a preferred embodiment, the steel used is covered with a layer of brass (Zn-Cu alloy) or zinc.

[0049] Preferably, the wires of the same layer of predetermined (inner or outer) strands all have substantially the same diameter. Advantageously, the outer strands all have substantially the same diameter. "Substantially the same diameter" means that the wires or strands have the same diameter within industrial tolerances.

[0050] Advantageously, the outer strands are helically wound around the inner strands with a lay length pe in the range 40 mm to 100 mm, preferably in the range 50 mm to 90 mm.

[0051] The energy per unit area is 171N.mm -1 Compared to the prior art cords, the cords according to the invention have a significantly higher energy per unit area. The inventors of the present invention have hypothesized that the greater the inter-thread contacts (more particularly in the inter-strand areas where the stresses are greatest) (i.e., the greater the contact between the outer metal wires of the inner strand and the outer metal wires of the outer strand), the greater the weakening load diluted by the number of contacts. This contact load depends on the load that each strand can react to, i.e., the cord load divided by the number of strands. In order to optimize these contacts, the inventors of the present invention have hypothesized that it is necessary to have good geometric properties in the contacts, more specifically in the contact angles between the outer metal wires of the inner strand and the outer metal wires of the outer strand, so as to optimize the contacts inside the cord.

[0052] Advantageously, ES≥180N.mm -1 , preferably, ES ≥ 185N.mm -1 .

[0053] Advantageously, the breaking force Fr≥25000 N is satisfied, preferably Fr≥26000 N, more preferably Fr≥28000 N. The breaking force is measured according to the standard ASTM D2969-04. As described above, the cord has a relatively high breaking force, thereby maximizing the breaking energy per unit area.

[0054] Another subject of the invention is a cord extracted from a polymer matrix, said cord comprising:

[0055] - an inner layer of cords, said inner layer of cords being composed of K=1 three-layer inner strands, said three-layer inner strands comprising:

[0056] - an inner layer consisting of Q inner metal wires,

[0057] - an intermediate layer consisting of M intermediate metal wires wound around the inner layer, and

[0058] an outer layer consisting of N outer metal wires of diameter d3 wound around the intermediate layer,

[0059] - an outer layer of cords, said outer layer of cords being composed of L>1 double-layer outer strands wound around an inner layer of cords, said double-layer outer strands comprising:

[0060] - an inner layer consisting of Q' = 2, 3 or 4 inner metal wires, and

[0061] - an outer layer consisting of N' outer metal wires with a diameter d3' wound around an inner layer, wherein the breaking energy ES' of the extracted cord is ≥ 170 N.mm -1 , in:

[0062] - is the sum of the breaking forces of Nc wires, in Newtons;

[0063] - Nc = Q + M + N + L × (Q' + N') is the total number of metal wires;

[0064] -D is the diameter of the cord, in mm;

[0065] - is the sum of the total elongation of Nc wires and is dimensionless;

[0066] -Cfrag' is the dimensionless weakening coefficient of the cord, where

[0067] in:

[0068] Cp is the permeability coefficient of the cord,

[0069] d3 and d3' are expressed in mm,

[0070] αf is the contact angle between the outer wire of the inner strand and the outer wire of the outer strand, expressed in radians,

[0071] αt is the helix angle of the outer strand, expressed in radians;

[0072] Cste=1500N.mm -2 .

[0073] Preferably, ES'≥175N.mm -1, more preferably, ES'≥180N.mm -1 .

[0074] The total elongation At of the extracted cord is measured in a similar manner to the total elongation At of the cord defined above.

[0075] The weakening coefficient, Cfrag', takes into account the degree of polymer matrix penetration into the cord using the interstrand permeability coefficient, Cp. To calculate this permeability coefficient, the extracted cord is cut into transverse sections using a saw. This operation is repeated ten times, resulting in ten transverse sections, over which the average permeability coefficient, Cp, can be calculated. The area of each extracted cord filled with the polymer compound is then observed using an electron microscope, and image processing software is used to quantify the ratio of the non-metallic surface area free of polymer compound to the surface area filled with polymer compound in the contact area between the outer and inner strands. Thus, a well-permeated cord has a permeability coefficient close to 1, while a less well-permeated cord has a permeability coefficient close to 0.5.

[0076] Preferably, the polymer matrix is an elastomeric matrix.

[0077] The polymer matrix, preferably an elastomeric matrix, is based on a polymer, preferably an elastomer, compound.

[0078] A polymer matrix is understood to mean a matrix comprising at least one polymer. The polymer matrix is therefore based on a polymer compound.

[0079] An elastomeric matrix is understood to mean a matrix comprising at least one elastomer. Preferred elastomeric matrices are therefore based on elastomeric compounds.

[0080] The expression "based on" is understood to mean that the compound comprises a mixture and / or in situ reaction products of the various components used, some of which are able and / or intended to react at least partially with one another during the various stages of manufacture of the compound; the compound may therefore be in a completely or partially crosslinked state or in a non-crosslinked state.

[0081] A polymer compound is understood to mean a compound comprising at least one polymer. Preferably, this polymer may be a thermoplastic polymer (such as polyester or polyamide), a thermosetting polymer, an elastomer (such as natural rubber), a thermoplastic elastomer, or a combination of these polymers.

[0082] An elastomeric compound is understood to mean a compound comprising at least one elastomer and at least one other component. Preferably, the compound comprising at least one elastomer and at least one other component comprises an elastomer, a crosslinking system, and a filler. Compounds that can be used for these plies are conventional compounds for surface coatings of filamentous reinforcing elements and comprise a diene elastomer (e.g., natural rubber), a reinforcing filler (e.g., carbon black and / or silica), a crosslinking system (e.g., a vulcanization system, preferably comprising sulfur, stearic acid, and zinc oxide, and possibly vulcanization accelerators and / or retarders and / or various additives). Adhesion between the metal threads and the matrix in which they are embedded is provided, for example, by a metal coating (e.g., a brass layer).

[0083] The values of the characteristics described in this application for the extracted cords are measured or determined on the cords extracted from a polymer matrix (particularly an elastomeric matrix), for example, of a tire. Thus, in order to be able to see the cord to be extracted radially flush with the polymer matrix, for example, on a tire, a strip of material radially outside the cord to be extracted is removed. This removal can be performed by stripping using a cutter and a clamp or by planing. The ends of the cord to be extracted are then exposed using a cutter. The cord is then pulled to extract it from the matrix, applying a relatively shallow angle to avoid plasticizing the cord to be extracted. The extracted cord is then carefully cleaned, for example using a cutter, to separate any residues of the polymer matrix that may have locally adhered to the cord, while taking care not to damage the surface of the metal wire.

[0084] Advantageously, the extracted cord exhibits a breaking force Fr' that satisfies It satisfies Fr' ≥ 24000 N, preferably Fr' ≥ 25000 N, more preferably Fr' ≥ 27000 N. The breaking force is measured on the extracted cords according to standard ASTM D2969-04.

[0085] The advantageous features described below apply equally to the cords and extracted cords defined above.

[0086] Preferably, the diameter D of the cord satisfies D≤6.0 mm, preferably 4.0 mm≤D≤5.5 mm. The diameter D is measured on the cord according to standard ASTM D2969-04.

[0087] Preferably, αf is greater than or equal to 0°, preferably greater than or equal to 5°.

[0088] Preferably, αf is less than or equal to 25°, preferably less than or equal to 20°.

[0089] Within this range of contact angles of 0° to 25°, the contact area is maximized and the cord is relatively well penetrated by the polymer compound.

[0090] Preferably, αt is greater than or equal to 0°, preferably greater than or equal to 5°.

[0091] Preferably, αt is less than or equal to 20°, preferably less than or equal to 15°, more preferably less than or equal to 10°.

[0092] Within this range of the helix angle, when tension is applied to the cord, the contact load between the outer strands and the inner strands is minimized.

[0093] Preferably, d1, d1', d2, d3, d3' are independently in the range of 0.25 mm to 0.50 mm, preferably 0.30 mm to 0.45 mm, more preferably 0.32 mm to 0.42 mm.

[0094] Advantageously, the outer layer of the cord is saturated so that, in a section of the cord perpendicular to the main axis of the cord, the interstrand distance of the outer strands is strictly less than 20 μm, said interstrand distance being defined as the shortest distance which on average separates the circular envelope in which two adjacent outer strands are inscribed.

[0095] By definition, the saturated layer of the cord is such that the interstrand distance of the outer strands is strictly less than 20 μm. The interstrand distance of the outer layer of outer strands is defined as the shortest distance separating, on average, the circular envelope in which two adjacent outer strands are inscribed, in a cross section of the cord perpendicular to the main axis of the cord. This construction of the cord thus ensures good structural stability of the outer layer, and the saturation of the outer layer ensures that the outer layer comprises a relatively large number of outer strands, thus exhibiting a relatively high breaking force.

[0096] The distance E between the strands is the distance between the two centers of two adjacent outer strands (e.g. Figure 7 The distance between points A and B shown) minus the diameter of the outer strand.

[0097] Preferably, the wires of the same layer of predetermined (inner or outer) strands all have substantially the same diameter. Advantageously, the outer strands all have substantially the same diameter. "Substantially the same diameter" means that the wires or strands have the same diameter within industrial tolerances.

[0098] For this purpose, in a standard orthogonal 2D reference system (i.e. along the cross section of the cable), with OA as the transverse axis, where O is the center of the cord, and taking into account the fact that the outer strands all have substantially the same diameter, the coordinates of the centers A and B of the two strands are calculated as: A = [Re TE ,0],B=[Re TE ×cos(2π / L);ReTE×sin(2π / L)], where L is the number of external strands, ReTE is the helix radius in millimeters for each outer strand.

[0099] Calculate the helix radius for each outer strand using the following formula: Re TE = max(Re_minTE; ReTE is unsaturated), where

[0100] Re_minTE is the winding radius obtained if the layer is supersaturated.

[0101] This is the minimum radius of all strands to be in contact.

[0102] Re_minTE=1 / [(sin 2 (π / L) / D TE / 2) 2 -cos 2 (π / L)×(2π / pe) 2 ]

[0103] Where L is the number of external strands, pe is the lay length of each external strand in millimeters, and D TE is the diameter of the outer strand in millimeters, and

[0104] Re TE不饱和 Corresponding to unsaturated or strictly saturated structures, Re TE不饱和 =D TI / 2+D TE / 2, where DTI is the diameter of the inner strand in mm, and D TE Diameter of the outer strands in millimeters.

[0105] The diameter of the outer strands is calculated as follows:

[0106] DTE = 2 × Re1' + d1' + 2 × d3', where Re1' is the winding radius of the inner layer of the outer strand,

[0107] - If the inner layer of the outer strands consists of a single inner metal wire, then Re1' = 0

[0108] -or Re1'=1 / [(sin2(π / Q') / d1' / 2)2-cos2(π / Q')×(2π / p1')2

[0109] Wherein Q' is the number of metal wires in the inner layer of the outer strands, d1' is the diameter of the metal wires of the inner layer of the outer strands in mm, and the lay pitch p1' is the lay pitch of the inner layer of the outer strands in mm.

[0110] Then, the distance AB in the reference frame is calculated using the following formula: AB = [(xb-xa) 2+(yb-ya) 2 ] 1 / 2 , then find the distance between the strands E = AB-D TE / cos(αt)×1000, in micrometers, where D TE is the diameter of the outer strand, αt=atan(2πReTE / pe) is the helix angle of the outer strand, where pe is the lay length of each outer strand wound, expressed in millimeters.

[0111] In contrast, the unsaturated layer of the cord is such that the interstrand distance of the outer strands is greater than or equal to 20 μm.

[0112] Advantageously, the outer layer of the inner strands is unsaturated.

[0113] By definition, an unsaturated layer satisfies the requirement that there is sufficient space between the filaments to allow the polymer compound (preferably an elastomeric compound) to pass through. An unsaturated layer means that the filaments are not in contact, and there is sufficient space between two adjacent filaments to allow the polymer compound (preferably an elastomeric compound) to pass through. In contrast, a saturated layer satisfies the requirement that there is insufficient space between the filaments of the layer to allow the polymer compound (preferably an elastomeric compound) to pass through, for example because the two filaments of each pair in the layer are in contact with each other.

[0114] By definition, the inter-filament distance of a layer is defined as the shortest distance which on average separates two adjacent filaments of the layer, in a cross section of the cord perpendicular to the main axis of the cord.

[0115] The distance between the threads of a layer is calculated as follows:

[0116] The winding radius of the outer layer of the outer strands is calculated as:

[0117] Re3'=Re1'+d1' / 2+d3' / 2

[0118] wherein Re1 ' is the winding radius of the inner layer of the outer strand as defined above.

[0119] The distance I3' between the threads is as follows Figure 7 The distance between the centers of the 2 wire strands shown is calculated by subtracting the wire diameter from the wire diameter, using the same calculation method used for the outer strands:

[0120] A'=[Re 3’ ,0]

[0121] B'=[Re 3’ ×cos(2π / N'); Re3'×sin(2π / N')]

[0122] A'B'=[(xb'-xa') 2 +(yb'-ya') 2 ]1 / 2

[0123] This then gives I3' = A'B' - d3' / cos(αC3') x 1000, where αC3' = atan(2πR3' / p3') is the helix angle of the outer layer of the outer strand.

[0124] The sum SI3' is the sum of the inter-wire distances that separate each pair of adjacent outer wires of the outer layer.

[0125] The sum SI2' is the sum of the inter-wire distances of each pair of adjacent intermediate wires that separate the outer layer.

[0126] Preferably, the filaments are not pre-formed.

[0127] Advantageously, the inter-filament distance of the outer layer of the inner strands is greater than or equal to 5 μm. Preferably, the inter-filament distance of the outer layer of the inner strands is greater than or equal to 15 μm, more preferably greater than or equal to 35 μm, still more preferably greater than or equal to 50 μm, and the height is preferably greater than or equal to 60 μm.

[0128] Preferably, the inter-filament distance of the outer layer of the inner strand is less than or equal to 100 μm.

[0129] Advantageously, the sum SI3 of the inter-wire distances I3 of the outer layer of the inner strands is greater than the diameter d3 of the outer wires of the outer layer.

[0130] Advantageously, each strand is of the type not rubberized in situ. Not rubberized in situ means that each strand consists of filaments of individual layers and does not have any polymer compound (in particular any elastomeric compound) before assembling the strands to each other.

[0131] Advantageously, the outer layer of each outer strand is unsaturated.

[0132] Advantageously, the inter-thread distance of the outer layer of each outer strand is greater than or equal to 5 μm. Preferably, the inter-thread distance of the outer layer of each outer strand is greater than or equal to 15 μm, more preferably greater than or equal to 35 μm, even more preferably greater than or equal to 50 μm, and the height is preferably greater than or equal to 60 μm.

[0133] Preferably, the inter-filament distance of the outer layer of each outer strand is less than or equal to 100 μm.

[0134] Advantageously, the sum SI3' of the inter-filament distances I3' of the outer layer of each outer strand is greater than or equal to the diameter d3' of the outer wires of the outer layer.

[0135] Preferably, d1, d1’, d2, d3, d3’ are independently in the range of 0.12 mm to 0.45 mm, preferably 0.15 mm to 0.40 mm, each other.

[0136] In one embodiment, the diameter d1 of each inner filament is strictly less than the diameter d3 of each outer filament, and preferably, d1 < d2 = d3. In another embodiment where d1 = d2 = d3, the number of different filaments to be managed can be restricted in the manufacture of the cord.

[0137] Preferably, the outer layer of the inner strand winds around the inner layer of the inner strand and contacts the inner layer of the inner strand.

[0138] Advantageously, L = 6, 7 or 8; preferably, L = 6 or 7, more preferably, L = 6.

[0139] Preferably, K = 1 and L = 6. In the cord with K = 1, the most severe lateral load is the lateral load exerted by the outer strand on the inner strand.

[0140] The inner strands of the cord according to the invention

[0141] In one embodiment, Q = 1.

[0142] Advantageously, M = 3, 4, 5 or 6, and preferably, M = 4, 5 or 6.

[0143] Advantageously, N = 9, 10, 11 or 12.

[0144] In another preferred embodiment, Q > 1, and preferably, Q = 2, 3 or 4.

[0145] Advantageously, M = 7, 8, 9 or 10, and preferably, M = 7, 8 or 9.

[0146] Advantageously, N = 12, 13, 14 or 15, and preferably, N = 12, 13 or 14.

[0147] In the first alternative form, Q = 2, M = 7 or 8, and N = 12 or 13.

[0148] In the second alternative form, Q = 3, M = 8 or 9, and N = 13 or 14.

[0149] In the third alternative form, Q = 4, M = 9 or 10, and N = 12, 13 or 14, preferably, Q = 4, M = 9, and N = 14.

[0150] Advantageously, the diameter d1 of each internal thread of the internal strand is equal to the diameter d2 of each intermediate thread of the internal strand and equal to the diameter d3 of each external thread of the internal strand. Thus, threads of the same diameter are preferably used in the inner, intermediate and outer layers of the internal strand, thus limiting the number of different threads that need to be managed during the manufacture of the cord.

[0151] The outer strands of the cord according to the invention

[0152] Advantageously, N′=7, 8, 9 or 10, and preferably, N′=8 or 9.

[0153] In a first alternative, Q'=2, and N'=7 or 8, preferably Q'=2, N'=7.

[0154] In a second alternative, Q'=3, and N'=7, 8 or 9, preferably Q'=3, N'=8.

[0155] In a third alternative, Q'=4, and N'=7, 8, 9 or 10, preferably Q'=4, N'=9.

[0156] Advantageously, the diameter d1 ′ of each inner thread of the outer strand is equal to the diameter d3 ′ of each outer thread of the outer strand. Thus, threads of the same diameter are preferably used in the inner and outer layers of the outer strand, thus limiting the number of different threads that need to be managed during the manufacture of the cord.

[0157] Advantageously, Q=4, M=9, N=14, Q′=4, N′=9, and d1=d3=d1′=d3′.

[0158] Enhanced product according to the invention

[0159] Another subject of the invention is a reinforced product comprising a polymer matrix and at least one cord or extracted cord as defined above.

[0160] Advantageously, the reinforced product comprises one or more cords according to the invention embedded in a polymer matrix and, in the case of a plurality of cords, said cords are arranged side by side in a main direction.

[0161] Tire according to the invention

[0162] Another subject of the invention is a tire comprising at least one extracted cord or reinforcement product as defined above.

[0163] A tire comprising an extracted cord means a tire comprising a cord whose properties measured after extraction from the tire are the properties of the extracted cord, such as the cords described above, before being incorporated into the tire.

[0164] Preferably, the tire has a carcass reinforcement anchored in two beads and radially covered by a crown reinforcement, itself covered by a tread, connected to the beads by two sidewalls and comprising at least one cord as defined above.

[0165] In a preferred embodiment, the crown reinforcement comprises a protective reinforcement and a working reinforcement comprising at least one cord as defined above, the protective reinforcement being radially interposed between the tread and the working reinforcement.

[0166] The cords are most particularly intended for industrial vehicles chosen from heavy vehicles (such as “heavy duty vehicles”, ie metros, buses, road transport vehicles (trucks, tractors, trailers), off-road vehicles, agricultural vehicles or construction site vehicles) or other transport or handling vehicles.

[0167] Preferably, the tire is for a construction site type vehicle. Thus, the tire has a size where the diameter in inches of the base of the rim on which the tire is intended to be mounted is greater than or equal to 40 inches.

[0168] The present invention also relates to a rubber product comprising the component according to the invention or comprising the impregnated component according to the invention. A rubber product is understood to mean any type of product made of rubber, such as a ball, a non-pneumatic object (e.g. a non-pneumatic tire casing), a conveyor belt or a crawler track. BRIEF DESCRIPTION OF THE DRAWINGS

[0169] The invention will be better understood on reading the following examples given purely by way of non-limiting example and with reference to the accompanying drawings, in which:

[0170] - Figure 1 is a cross-sectional view perpendicular to the circumferential direction of the tire according to the invention;

[0171] - Figure 2 for Figure 1 Detail of Area II;

[0172] - Figure 3 is a cross-sectional view of a reinforced product according to the present invention;

[0173] - Figure 4 is a schematic diagram of a cross section perpendicular to the cord axis (assuming the cord is straight and stationary) of a cord (50) according to one embodiment of the present invention;

[0174] - Figure 5is a schematic diagram of a cross section perpendicular to the cord axis (assuming the cord is straight and stationary) of an extracted cord (50') according to one embodiment of the present invention;

[0175] - Figure 6 for Figure 4 A schematic diagram of the angle αf of the cord (50); and

[0176] - Figure 7 Schematic diagram of different geometric parameters of the cord. DETAILED DESCRIPTION

[0177] Figure 1 and Figure 2 Reference frames X, Y, Z are depicted corresponding to the general axial (X), radial (Y) and circumferential (Z) directions of the tire, respectively.

[0178] The “median circumferential plane” M of the tyre is the plane perpendicular to the axis of rotation of the tyre and equidistant from the annular reinforcing structure of each bead.

[0179] Figure 1 and Figure 2 A tyre according to the invention is shown, indicated generally at 10 .

[0180] The tyre 10 is intended for heavy vehicles of the construction site type, for example of the "dump truck" type. The tyre 10 therefore has a size of the 53 / 80R63 type.

[0181] The tire 10 comprises a crown 12, reinforced by a crown reinforcement 14, two sidewalls 16, and two beads 18, each of these beads 18 being reinforced with an annular structure, in this case a bead wire 20. The crown reinforcement 14 is radially covered by a tread 22 and connected to the beads 18 by the sidewalls 16. A carcass reinforcement 24 is anchored in the two beads 18 (in this case wound around two bead wires 20) and comprises a turn-up 26 arranged towards the outside of the tire 20, which is shown here mounted on a wheel rim 28. The carcass reinforcement 24 is radially covered by the crown reinforcement 14.

[0182] The carcass reinforcement 24 comprises at least one carcass ply 30 reinforced by radial carcass cords (not shown). The carcass cords are arranged substantially parallel to one another and extend from one bead 18 to the other, making an angle of between 80° and 90° with the median circumferential plane M (a plane perpendicular to the axis of rotation of the tire, midway between the two beads 18 and passing through the center of the crown reinforcement 14).

[0183] The tire 10 also comprises a sealing ply 32 made of elastomer (commonly called “inner liner”) which defines a radially inner surface 34 of the tire 10 and is intended to protect the carcass ply 30 from the diffusion of air from the interior space of the tire 10 .

[0184] The crown reinforcement 14 includes, radially from the outside toward the inside of the tire 10, a protective reinforcement 36, a working reinforcement 38, and an additional reinforcement 40. The protective reinforcement 36 is arranged radially inside the tread 22, the working reinforcement 38 is arranged radially inside the protective reinforcement 36, and the additional reinforcement 40 is arranged radially inside the working reinforcement 38. Therefore, the protective reinforcement 36 is radially inserted between the tread 22 and the working reinforcement 38. The working reinforcement 38 is radially inserted between the protective reinforcement 36 and the additional reinforcement 40.

[0185] The protective reinforcement 36 comprises a first protective ply 42 and a second protective ply 44 comprising protective metal cords, the first ply 42 being arranged radially on the inside of the second ply 44. Optionally, the protective metal cords form an angle with the circumferential direction Z of the tire of at least 10°, preferably ranging from 10° to 35° and more preferably from 15° to 30°.

[0186] The working reinforcement 38 comprises a first working ply 46 and a second working ply 48, the first ply 46 being arranged radially on the inside of the second ply 48. Each ply 46, 48 comprises at least one cord 50. Optionally, the working metal cords 50 are crossed from one working ply to the other and form an angle with the circumferential direction Z of the tire of at most 60°, preferably ranging from 15° to 40°.

[0187] The additional reinforcement 40 (also called a limiter, the purpose of which is to partially absorb the mechanical stresses of inflation) comprises, for example and in a manner known per se, an additional metallic reinforcing element, such as described in FR 2419181 or FR 2419182, which forms an angle with the circumferential direction Z of the tyre 10 of at most 10°, preferably ranging from 5° to 10°.

[0188] Examples of enhanced products according to the present invention

[0189] Figure 3 There is depicted a reinforced product according to the invention, indicated overall with 100. The reinforced product 100 comprises at least one cord 50 (in this case a plurality of cords 50) embedded in a polymer matrix 102.

[0190] Figure 3The polymer matrix 102 and the cord 50 are depicted in a reference frame X, Y, Z, wherein direction Y is the radial direction and directions X and Z are the axial and circumferential directions. Figure 3 In the embodiment of the present invention, the reinforced product 100 comprises a plurality of cords 50 arranged side by side in a main direction X, extending parallel to one another within the reinforced product 100 and being jointly embedded in a polymer matrix 102 .

[0191] In this case, the polymer matrix 102 is an elastomeric matrix based on an elastomeric compound.

[0192] Cord according to the first embodiment of the present invention

[0193] Figure 4 A cord 50 according to a first embodiment of the invention is depicted.

[0194] refer to Figure 5 Each protective reinforcing element 43, 45 and each hooping reinforcing element 53, 55 is formed from an extracted cord 50' as described below, after extraction from the tire 10. The cord 50 is obtained by embedding in a polymer matrix, in this case, in a polymer matrix forming each polymer matrix of each protective ply 42, 44 and each hooping ply 52, 54 in which the protective reinforcing elements 43, 45 and the hooping reinforcing elements 53, 55, respectively, are embedded.

[0195] The cord 50 and the extracted cord 50' are made of metal and are of the multi-strand type having two cylindrical layers. It will therefore be understood that there are two (no more, no less) layers of strands made of the cord 50 or 50'.

[0196] The cord 50 or cord 50' comprises an inner layer CI composed of K = 1 inner strands TI. An outer layer CE is composed of L > 1 outer strands TE wound around the inner layer CI. In this particular case, L = 6, 7, or 8; preferably, L = 6 or 7, more preferably, L = 6, in this case L = 6.

[0197] The breaking energy per unit area of the cord 50 is:

[0198]

[0199]

[0200] Wherein Nc=Q+M+N+L×(Q′+N′)=1+4+9+6×(4+9)=92.

[0201]

[0202]

[0203] The cord 50 also comprises a covering F (not shown) made of a single covering filament.

[0204] The breaking energy per unit area of the extracted cord 50' is:

[0205]

[0206] To calculate Cp, the software is used to determine the ratio of the non-metallic surface area without polymer compound to the surface area filled with polymer compound in the contact area Scp between the outer and inner strands. Here, the ratio averaged over 10 transverse cross sections is equal to 0.9.

[0207]

[0208] The outer layers of the cords 50 and 50' are saturated. Therefore, the interstrand distance E of the outer strands is strictly less than 20 μm. Here, E=0 μm.

[0209] αf is greater than or equal to 0°, preferably greater than or equal to 5° and less than or equal to 25°, preferably less than or equal to 20°. Here, αf=5.5°.

[0210] αt is greater than or equal to 0°, preferably greater than or equal to 5° and less than or equal to 20°, preferably less than or equal to 15°, more preferably less than or equal to 10°. Here, αt=9.1°.

[0211] Inner strands TI of cords 50 and 50'

[0212] Each internal strand TI is a three-layer strand, including an inner layer C1 composed of Q=1 internal metal wires F1, an intermediate layer C2 composed of M intermediate metal wires F2 wound around the inner layer C1, and an outer layer C3 composed of N external metal wires F3 wound around the intermediate layer C2.

[0213] Here, Q=1.

[0214] Advantageously, M=3, 4, 5 or 6, and preferably, M=4, 5 or 6. Here, M=4.

[0215] Advantageously, N=9, 10 or 11. Here, N=9.

[0216] The outer layer C3 of each inner strand TI is unsaturated. The inter-filament distances of the outer layer of the inner strands are greater than or equal to 15 μm, more preferably greater than or equal to 35 μm, and here equal to 71 μm. The sum SI3 of the inter-filament distances I3 of the outer layer C3 is greater than the diameter d3 of the outer threads F3 of the outer layer C3. Here, the sum SI3 = 0.71 × 9 = 0.64 mm, which is greater than d3 = 0.40 mm.

[0217] The range of d1, d2 and d3 is independently 0.12 mm to 0.45 mm, preferably 0.15 mm to 0.40 mm. Here, d1 = 0.20 mm and d2 = d3 = 0.40 mm.

[0218] Outer strands TE of cords 50 and 50'

[0219] Each outer strand TE has two layers, including an inner layer C1 ′ constituted by Q′ inner metal wires F1 ′ and an outer layer C3 ′ constituted by N′ outer metal wires F3 ′ wound around the inner layer C1 ′.

[0220] Here, Q'=4.

[0221] N'=7, 8, 9 or 10, and preferably, N'=8 or 9, where N'=9.

[0222] The outer layer C3' of each outer strand TE is unsaturated. Because it is unsaturated, the inter-filament distance I3' of the outer layer C3', which separates the N' outer filaments on average, is greater than or equal to 5 μm. The inter-filament distance I3' of the outer layer of each outer strand is greater than or equal to 15 μm, more preferably greater than or equal to 35 μm, even more preferably greater than or equal to 50 μm, and here is equal to 0.55 μm. The sum SI3' of the inter-filament distances I3' of the outer layer C3' is greater than the diameter d3' of the outer filaments F3' of the outer layer C3'. Here, the sum SI3' = 61 × 9 = 0.55 mm, which is greater than d3' = 0.40 mm.

[0223] Each inner layer C1 ' and outer layer C3' of each outer strand TE is wound in the same winding direction of the cord as the inner layer C1 and outer layer C3 of the inner strand TI. Here, the winding direction of each layer of the cord and of the cord itself is Z.

[0224] Each inner wire and outer wire of each outer strand TE has a diameter d1' and d3' respectively. The diameter d1' of each inner metal wire F1' of each outer strand TE is greater than or equal to the diameter d3' of each outer metal wire F3' of each outer strand TE; preferably, 1.00≤d1' / d3'≤1.20.

[0225] The range of d1' and d3' is independently 0.12 mm to 0.45 mm, preferably 0.15 mm to 0.40 mm. Here, d1'=d3'=0.40 mm.

[0226] The cords 50 and 50 ′ satisfy Q=1, M=4 and N=9, and Q′=4 and N′=9.

[0227] At least 50% of the metal wires of the cord, preferably at least 60%, more preferably at least 70%, highly preferably each metal wire comprises a steel core having a composition according to standard NF EN 10020 of September 2000 and a carbon content C>0.80%, preferably C≥0.82%, and at least 50% of the metal wires of the cord, preferably at least 60%, more preferably at least 70%, highly preferably each metal wire comprises a steel core having a composition according to standard NF EN 10020 of September 2000 and a carbon content C≤1.20%, preferably C≤1.10%. Here, each metal wire comprises a steel core having a composition according to standard NF EN 10020 of September 2000 and a carbon content C=1%.

[0228] The breaking strength (denoted as Rm) of each wire satisfies 2500 MPa≤Rm≤3100 MPa. The steel of these wires is referred to as SHT ("super high strength") grade. Other wires may be used, for example lower grade wires such as NT ("normal strength") or HT ("high strength") grades, or higher grade wires such as UT ("extra strength") or MT ("mega strength") grades.

[0229] Method for producing a cord according to the invention

[0230] One embodiment of a method of manufacturing the multi-strand cord 50 will now be described.

[0231] Each of the aforementioned internal strands is manufactured according to a known method comprising the following steps, preferably carried out in sequence and continuously:

[0232] - first a first assembly step, forming the inner layer C1 at a first assembly point by cabling its Q=1 internal threads F1 in the Z direction with a lay pitch p1;

[0233] - followed by a second assembly step of forming the intermediate layer C2 at a second assembly point by cabling or twisting M=4 intermediate threads F2 in the Z direction with a lay pitch p2 around the internal threads F1 of the inner layer C1 ;

[0234] - followed by a third assembly step of assembling the outer layer C3 at a third assembly point by cabling or twisting N=9 outer threads F3 with a lay length p3 in the Z direction around the M intermediate threads F2 of the intermediate layer C2;

[0235] - Preferably, a final twist balancing step.

[0236] Each of the aforementioned outer strands is manufactured according to a known method comprising the following steps, preferably carried out in sequence and continuously:

[0237] - first a first step of assembly, forming the inner layer C1 ′ at a first assembly point by cabling its Q′=4 internal threads F1 ′ in the S direction with a lay pitch p1 ′;

[0238] - followed by a second assembly step, by cabling or twisting N′=9 external threads F3′ with a lay length p3′ in the S direction around the Q′ internal threads F1′ of the inner layer C1′, so as to form the outer layer C3′ at a second assembly point;

[0239] - Preferably, a final twist balancing step.

[0240] As is known to those skilled in the art, "twist balance" here means the elimination of the residual torque applied to each filament of the strand (or elastic recovery of the twist) in the middle and outer layers.

[0241] After this final twist balancing step, the manufacture of the strands is complete.Before the subsequent operation of cabling the elementary strands together to obtain a multistrand cord, each strand is wound onto one or more take-up drums for storage.

[0242] To manufacture the multistrand cord of the invention, the method is to cable or twist together the strands previously obtained using a cabling or twisting machine of a size matching that of the assembled strands, as is well known to those skilled in the art.

[0243] Thus, L external strands TE are assembled in the Z direction with a lay pe around the internal strands TI, forming the cord 50. Possibly, in a final assembly step, a sheath F is wound in the S direction with a lay pf around the assembly previously obtained.

[0244] The cords 50 are then incorporated by calendering into a composite fabric formed from a known compound based on natural rubber and carbon black as a reinforcing filler, and commonly used in the manufacture of crown reinforcements for radial tires. Besides the elastomer and the reinforcing filler (carbon black), this compound essentially contains an antioxidant, stearic acid, an extender oil, cobalt naphthenate as an adhesion promoter, and finally a vulcanization system (sulfur, accelerators, and ZnO).

[0245] The composite fabrics reinforced with these cords have an elastomeric compound matrix formed by two thin layers of elastomeric compound superimposed on either side of the cord and each having a thickness ranging from 1 mm to 4 mm. The calendering pitch (the distance between the cords in the elastomeric compound fabric) ranges from 4 mm to 8 mm.

[0246] These composite fabrics are then used as working plies in the crown reinforcement during a process for manufacturing a tire, the steps of which are known to those skilled in the art.

[0247] Table 1 below summarizes the characteristics of the various cords 50 and 50 ′.

[0248] [Table 1]

[0249]

[0250]

[0251] Comparative testing

[0252] Evaluation of fracture energy per unit area

[0253] Various control cords and prior art cords were simulated.

[0254] Table 2 summarizes the characteristics of a cord EDT of the prior art (Example 2 of EP2426255).

[0255] [Table 2]

[0256]

[0257] Tables 1 and 2 show that the cords 50 and 50' exhibit improved breaking energy per unit area relative to the prior art cords EDT and EDT'. Specifically, the cords EDT and EDT' have relatively high weakening coefficients, but relatively low breaking forces, resulting in insufficient breaking energy per unit area to reduce the number of cord breaks and punctures in the tire. Thus, the cords according to the present invention have a breaking energy per unit area ES ≥ 175 N.mm -1 , which is high enough to overcome these shortcomings.

[0258] The present invention is not limited to the above-described embodiments.

Claims

1. A double-layer multi-strand cord (50), comprising: - an inner layer (CI) of cords consisting of K=1 inner strands (TI) having three layers (C1, C2, C3), said inner strands (TI) comprising: - an inner layer (C1) consisting of Q inner metal wires (F1), - an intermediate layer (C2) consisting of M intermediate metal wires (F2) wound around the inner layer (C1), and an outer layer (C3) consisting of N external metal wires (F3) of diameter d3 wound around the intermediate layer (C2), - a cord outer layer (CE) consisting of L>1 external strands (TE) of two layers ( C1 ′, C3 ′) wound around a cord inner layer (CI), said external strands (TE) comprising: - an inner layer (C1') consisting of Q'=2, 3 or 4 inner metal wires (F1'), and an outer layer (C3') consisting of N' outer metal wires (F3') of diameter d3' wound around the inner layer (C1'), It is characterized by The cord (50) has a breaking energy per unit area ES≥175N.mm -1 , in: - is the sum of the breaking forces of Nc wires, in Newtons; - Nc = Q + M + N + L × (Q' + N') is the total number of metal wires; -D is the diameter of the cord, in mm; - is the sum of the total elongation of Nc wires and is dimensionless; - Cfrag is the dimensionless weakening coefficient of the cord (50), where in: d3 and d3' are expressed in mm, αf is the contact angle between the outer wire (F3) of the inner strand (TI) and the outer wire (F3') of the outer strand (TE), expressed in radians, αt is the helix angle of each external strand (TE), expressed in radians; Cste=1500N.mm -2 ; The total elongation At is determined by applying the 2014 standard ASTM D2969-04.

2. The double-layer multi-strand cord (50) according to claim 1, wherein ES≥180N.mm -1 。 3. The double-layer multi-strand cord (50) according to claim 1 or 2, wherein the breaking strength of the cord (50) is Satisfy Fr≥25000N.

4. The double-layer multi-strand cord (50) according to claim 1, wherein The diameter D of the cord (50) satisfies D≤6.0 mm.

5. The double-layer multi-strand cord (50) according to claim 1, wherein αf is greater than or equal to 0°.

6. The double-layer multi-strand cord (50) according to claim 1, wherein αf is less than or equal to 25°.

7. The double-layer multi-strand cord (50) according to claim 1, wherein αt is greater than or equal to 0°.

8. The double-layer multi-strand cord (50) according to claim 1, wherein αt is less than or equal to 20°.

9. The double-layer multi-strand cord (50) according to claim 1, wherein The outer layer (CE) of the cord is saturated so that the inter-strand distance of the outer strands is strictly less than 20 μm, and the inter-strand distance is defined as the shortest distance of the circular envelope in which two adjacent outer strands (TE) are inscribed on average in the cord section perpendicular to the main axis of the cord (50).

10. The double-layer multi-strand cord (50) according to claim 1, wherein The outer layer (C3) of the inner strand (TI) is unsaturated.

11. The double-layer multi-strand cord (50) according to claim 1, wherein The outer layer (C3') of each outer strand (TE) is unsaturated.

12. A cord (50') extracted from a polymer matrix, the extracted cord (50') comprising: - an inner layer (CI) of cords consisting of K=1 inner strands (TI) having three layers (C1, C3), said inner strands (TI) comprising: - an inner layer (C1) consisting of Q inner metal wires (F1), - an intermediate layer (C2) consisting of M intermediate metal wires (F2) wound around the inner layer (C1), and an outer layer (C3) consisting of N external metal wires (F3) of diameter d3 wound around the intermediate layer (C2), - a cord outer layer (CE) consisting of L>1 external strands (TE) of two layers ( C1 ′, C3 ′) wound around a cord inner layer (CI), said external strands (TE) comprising: - an inner layer (C1') consisting of Q'=2, 3 or 4 inner metal wires (F1'), and an outer layer (C3') consisting of N' outer metal wires (F3') of diameter d3' wound around the inner layer (C1'), It is characterized by The extracted cord (50') has a breaking energy ES'≥170N.mm -1 , in: - is the sum of the breaking forces of Nc wires, in Newtons; - Nc = Q + M + N + L × (Q' + N') is the total number of metal wires; -D is the diameter of the cord, in mm; - is the sum of the total elongation of Nc wires and is dimensionless; - Cfrag' is the dimensionless weakening coefficient of the cord (50'), where in: Cp is the permeability coefficient of the cord, d3 and d3' are expressed in mm, αf is the contact angle between the outer wire (F3) of the inner strand (TI) and the outer wire (F3') of the outer strand (TE), expressed in radians, αt is the helix angle of the external strand (TE), expressed in radians; Cste=1500N.mm -2 ; The total elongation At is determined by applying the 2014 standard ASTM D2969-04.

13. The cord (50') extracted from a polymer matrix according to claim 12, wherein ES'≥175N.mm -1 。 14. Cord (50') extracted from a polymer matrix according to claim 12 or 13, wherein The diameter D of the cord (50') satisfies D≤6.0 mm.

15. The cord (50') extracted from a polymer matrix according to claim 12, wherein αf is greater than or equal to 0°.

16. The cord (50') extracted from a polymer matrix according to claim 12, wherein αf is less than or equal to 25°.

17. The cord (50') extracted from a polymer matrix according to claim 12, wherein αt is greater than or equal to 0°.

18. The cord (50') extracted from a polymer matrix according to claim 12, wherein αt is less than or equal to 20°.

19. The cord (50') extracted from a polymer matrix according to claim 12, wherein The outer layer (CE) of the cord is saturated so that the interstrand distance of the external strands is strictly less than 20 μm, the interstrand distance being defined as the shortest distance separating on average the circular envelope in which two adjacent external strands (TE) are inscribed, on a cross section of the cord perpendicular to the main axis of the cord (50′).

20. The cord (50') extracted from a polymer matrix according to claim 12, wherein The outer layer (C3) of the inner strand (TI) is unsaturated.

21. The cord (50') extracted from a polymer matrix according to claim 12, wherein The outer layer (C3') of each outer strand (TE) is unsaturated.

22. Enhanced product (100), characterized in that The reinforced product (100) comprises a polymer matrix (102) and at least one cord (50') extracted from the polymer matrix according to any one of claims 12 to 21.

23. A tire (10), characterized in that The tire (10) comprises at least one cord (50') extracted from a polymer matrix according to any one of claims 12 to 21 or a reinforcement product according to claim 22.

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