Two-layer multi-strand cable with improved surface breakdown energy

Abstract

The present invention relates to a multi-strand cable (50) comprising an inner cable layer (CI) consisting of K=1 inner strands (TI) with two plies (C1, C3) of which the inner ply (C1) consists of Q wires (F1) and the outer ply (C3) consists of N outer wires (F3), and an outer cable layer (CE) consisting of L>1 outer strands (TE) wound on the inner cable layer (CI), with the inner ply (C1) consisting of Q' inner wires (FT) and the outer ply (C3') consisting of two plies (CT, C3') of which the inner ply (C3') consists of N' outer wires (F3'). The cable (50) has a surface rupture energy ES≥145 N.mm -1 and TIFF2023503055000027.tif21153 where TIFF2023503055000028.tif21153 is the total breaking force of Nc metal wires, TIFF2023503055000029.tif21153 is the sum of the total elongation rates of the Nc metal wires, Cfrag is the embrittlement factor of the cable (50), and D is the diameter of the cable (50).

Description

[Technical Field]

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

[0002] From the prior art, in particular from WO 2016 / 017655, a tire for a plant construction vehicle is known, which has a radial carcass reinforcement including a tread portion, two inelastic bead portions, two sidewall portions connecting the bead portions to the tread portion, and a crown reinforcement arranged circumferentially between the carcass reinforcement and the tread portion, the crown reinforcement including four plies reinforced by reinforcing elements such as metal cords, the cords of one ply being embedded in the elastomer matrix of the ply.

[0003] The crown reinforcement includes a plurality of working plies, each of which includes a plurality of filamentary reinforcing elements. Each working filamentary reinforcing element is a two-ply multistrand cord having an inner layer of cord consisting of K=1 two-ply inner strands, with an inner layer consisting of Q=3 inner metal threads with a diameter d1=0.25 mm and an outer layer consisting of N=8 outer metal threads with a diameter d3=0.33 mm wound around the inner layer, and an outer layer of cord consisting of L=6 two-ply outer strands, with an inner layer consisting of Q'=3 inner metal threads with a diameter d1'=0.29 mm and an outer layer consisting of N'=9 outer metal threads with a diameter d3'=0.29 mm wound around the inner layer. For a breaking force of 17,572 N, the diameter of the unwrapped cord is equal to 3.72 mm.

[0004] On the one hand, when the tire passes over obstacles, for example in the form of stones, there is a risk that these obstacles will perforate the tire down to the crown reinforcement, which will allow corrosive agents to penetrate the crown reinforcement of the tire, shortening the tire's service life.

[0005] On the other hand, it has been found that the cords of the crown ply may exhibit failure due to the relatively significant deformations and loads that are applied to the cords, particularly when the tire passes over obstacles. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2016 / 017655 [Patent Document 2] French Patent No. 2419181 [Patent Document 3] French Patent No. 2419182 Summary of the Invention [Problem to be solved by the invention]

[0007] One subject of the present invention is a cord that makes it possible to reduce or eliminate the number of breakages and perforations. [Means for solving the problem]

[0008] To this end, one subject of the present invention is a two-layer multistrand cord, Q = an inner layer consisting of 2, 3 or 4 inner metal threads; and an outer layer consisting of N outer metal threads of diameter d3 wound around the inner layer; an inner layer of the cord consisting of K=1 two-layer inner strands including Q' = an inner layer consisting of 2, 3 or 4 inner metal threads, and an outer layer consisting of N' outer metal threads of diameter d3' wound around the inner layer; an outer layer of cord comprising L>1 two-layer outer strands wrapped around the inner layer of cord, The cord has a breaking energy per unit area ES≧ 155 N.mm -1 and JPEG0007737372000001.jpg6170, where: JPEG0007737372000002.jpg6170 is the total breaking force in Newtons of Nc threads, Nc=Q+N+L×(Q'+N') is the total number of metal threads, D is the diameter of the cord in mm, JPEG0007737372000003.jpg6170 is the sum of the total elongation rates of Nc threads and is dimensionless, Cfrag is the dimensionless weakening factor of the code, JPEG0007737372000004.jpg12170, where d3 and d3' are expressed in mm, αf is the contact angle between the outer metal thread of the inner strand and the outer metal thread of the outer strand, expressed in radians; αt is the helix angle of each outer strand, expressed in radians; Cste=1500N.mm -2 That is the code.

[0009] The cord according to the present invention has a relatively high breaking energy per unit area, which reduces perforations and therefore extends the life of the tire and also allows for a reduction in the number of breaks. Specifically, the inventors of the present invention have discovered that the criterion for reducing cord breakage is not only the breaking force, as widely taught in the prior art, but also the breaking energy per unit area, which in the present application is represented by an index equal to the product of the breaking force, the breaking elongation and the weakening factor of the cord, divided by the diameter of the cord.

[0010] The weakening factor allows taking into account the loss of tensile behavior of the cord caused by the transverse weakening of the inter-thread contact at the level of the outer metal threads of the inner and outer layers. This weakening factor depends on the number of outer metal threads of the inner layer, the contact angle between the inner strand and the or each outer strand, the diameter d3 of the outer metal threads of the inner layer and the diameter d3' of the outer metal threads of the outer layer, the helix angle of the outer strands, and the breaking force of the outer strands. Thus, a strong cord has a weakening factor close to 1, while a weakened cord has a suboptimal weakening factor closer to 0.5.

[0011] Specifically, prior art cords either have a relatively high breaking force but a suboptimal weakening coefficient, or, as in Example 8 of WO 2016 / 017655, an optimal weakening coefficient, i.e., close to 1, but a relatively low breaking force. In either case, prior art cords have a relatively low breaking energy per unit area. The cord according to the present invention exhibits a relatively high breaking elongation and a relatively high breaking energy per unit area due to its relatively high weakening coefficient and relatively high breaking force.

[0012] Any numerical range expressed as "between a and b" refers to a numerical range greater than a and less than b (i.e., excluding the endpoints a and b), whereas a numerical range expressed as "from a to b" refers to a numerical range from the endpoint a to the endpoint b (i.e., including the exact endpoints a and b).

[0013] By definition, the diameter of a strand is the diameter of the smallest circle that can circumscribe the strand.

[0014] Advantageously, the diameter of the cord is the diameter of the smallest circle circumscribing the cord, not including the wrapper. The cord preferably has a diameter D such that D≦6.0 mm, and preferably has a diameter D such that 5.0 mm≦D≦5.5 mm. Diameter D is measured on the cord in accordance with ASTM standard D2969-04.

[0015] In the present invention, the cord has two layers of strands, ie, it comprises an assembly made up of exactly two layers of strands, ie, the assembly has only two layers of strands, rather than one or three layers.

[0016] In one embodiment, the inner strands of the cord are surrounded by a polymeric compound which is then surrounded by an outer layer.

[0017] Advantageously, the inner strand has a cylindrical layer.

[0018] Advantageously, each outer strand has a cylindrical layer.

[0019] It is highly advantageous for the inner strand and each outer strand to have a cylindrical layer. It will be recalled that such a cylindrical layer is obtained when the various layers of the strand are wound with different pitches and / or when the winding direction of these layers differs from layer to layer. Unlike strands with dense layers, in which the pitch of all layers and the winding direction of all layers are the same, and which exhibit a much lower permeability, strands with cylindrical layers are very permeable.

[0020] The inner strand is a two-ply strand. The inner strand includes a group of threads that is made up of exactly two layers of threads, i.e., the group of threads has only two layers of threads, not one or three layers.

[0021] The outer strand is a two-ply strand. The outer strand includes a group of threads that is made up of exactly two layers of threads, i.e., the group of threads has only two layers of threads, not one or three layers.

[0022] As is well known, it will be recalled that the pitch of a strand denotes the length of this strand measured parallel to the axis of the cord, the strand having this pitch then being rotated through 180° around the axis of said cord, and similarly, the pitch of a thread denotes the length of this thread measured parallel to the axis of the strand in which it is located, the thread having this pitch then being rotated through 180° around the axis of said strand.

[0023] The winding direction of a layer of strands or threads is the direction in which the strands or threads occur relative to the axis of the cord or strand. The winding direction is commonly designated by the letters Z or S.

[0024] The pitch, winding direction and diameter of the threads and strands are determined in accordance with ASTM Standard D2969-04, 2014.

[0025] The contact angle between the outer metal threads of the inner strand and the outer metal threads of the outer strand is the angle αf shown in Figure 7. This schematic diagram of a cord according to the invention shows the axis A-A' of the cord around which the inner and outer layers are wound. In this diagram, only the two metal threads of the outer layer of the outer strand are retained in order to better see the angle αf, which is the contact angle between the outer metal threads of the inner strand and the outer metal threads of the outer strand. This contact angle is one of the relevant parameters in determining the weakening factor of a cord, since the smaller the contact angle, the less the cord will weaken.

[0026] The helix angle αt of each outer strand is a parameter known to those skilled in the art and can be determined using the calculation tan αt = 2 x π x Re / Pe, where p e is the winding pitch of each outer strand in millimeters, re is the helix radius of each outer strand in millimeters, and tan denotes the tangent function. αt is expressed in degrees.

[0027] By definition, the helix radius Re of the outer layer of the cord is the radius of a theoretical circle passing through the centres of the outer strands of the outer layer in a plane perpendicular to the axis of the cord.

[0028] The total elongation At, a parameter well known to those skilled in the art, is determined by applying, for example, the 2014 ASTM standard D2969-04 to a thread tested in such a way as to obtain a force-elongation curve. From this curve, At is estimated as the elongation in % corresponding to the thread's break point on the force-elongation curve, i.e., the point where the load increases to a maximum value of the breaking force (Fm) and then suddenly decreases after breakage, projected onto the elongation axis. If the decrease in Fm exceeds a certain level, it means that the thread has broken.

[0029] Preferably, the strands are not preformed.

[0030] Advantageously, the cord is made of metal. The term "metallic cord" is understood to mean, by definition, a cord made up of threads mainly (i.e., more than 50% of these threads) or entirely (100% of the threads) of a metallic material. Such metallic material is preferably implemented using a material made of steel, and even more preferably using a material made of pearlitic (or ferritic-pearlitic) carbon steel, hereinafter referred to as "carbon steel", or a material made of stainless steel (a stainless steel containing, by definition, at least 11% chromium and at least 50% iron). However, it is of course also possible to use other steels or other alloys.

[0031] If 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 representing a good compromise between the mechanical properties required for the tire and the processing properties of the thread.

[0032] The metal or steel used, whether specifically carbon steel or stainless steel, can itself be coated with a metal layer that improves, for example, the processing properties of the metal cord and / or its components, or the use properties of the cord and / or the tire itself, such as adhesion, corrosion resistance or ageing resistance. According to one preferred embodiment, the steel used is covered with a layer of brass (Zn-Cu alloy) or zinc.

[0033] Preferably, the threads of one and the same layer of a given (internal or external) strand all have substantially the same diameter. Advantageously, the external strands all have substantially the same diameter. By "substantially the same diameter" is meant that the threads or strands have the same diameter within industrial tolerances.

[0034] Advantageously, the outer strands are wound helically around the inner strands with a pitch pe ranging from 40 mm to 100 mm, preferably from 50 mm to 90 mm.

[0035] The cord according to the present invention has a strength of 120 N.mm -1 The present inventors have a significantly improved energy per unit area compared to prior art cords, which have an energy per unit area of ​​0.05 ...

[0036] ES≧160N.mm -1Advantageously, ES≧165N.mm -1 It is preferable that ES≧170N.mm -1 It is more preferable that:

[0037] Breaking force: TIFF0007737372000005.tif21153 Advantageously, Fr≧25,000 N, preferably Fr≧26,000 N, and more preferably Fr≧28,000 N. The breaking force is measured in accordance with ASTM standard D2969-04. As mentioned above, this cord has a relatively high breaking force to maximize the breaking energy per unit area.

[0038] Another subject of the invention is an extraction code extracted from a polymer matrix, comprising: Q = an inner layer consisting of 2, 3 or 4 inner metal threads; and an outer layer consisting of N outer metal threads of diameter d3 wound around the inner layer; an inner layer of the cord consisting of K=1 two-layer inner strands including Q' = an inner layer consisting of 2, 3 or 4 inner metal threads, and an outer layer consisting of N' outer metal threads of diameter d3' wound around the inner layer; an outer layer of cord comprising L>1 two-layer outer strands wrapped around an inner layer of cord, The extraction cord has a breaking energy ES'≧150N.mm -1 and TIFF0007737372000006.tif21153 where: TIFF0007737372000007.tif21153 is the total breaking force in Newtons of Nc threads, Nc=Q+N+L×(Q'+N') is the total number of metal threads, D is the diameter of the cord in mm, TIFF0007737372000008.tif21153 is the sum of the total elongation rates of Nc threads and is dimensionless, Cfrag' is the dimensionless weakening factor of the chord, TIFF0007737372000009.tif22153 where: Cp is the permeability coefficient of the cord; d3 and d3' are expressed in mm, αf is the contact angle between the outer metal thread of the inner strand and the outer metal thread of the outer strand, expressed in radians; αt is the helix angle of the outer strand, expressed in radians; Cste=1500N.mm -2 That is the code.

[0039] ES'≧155N.mm -1 It is preferable that ES'≧160N.mm -1 It is more preferable that:

[0040] The total elongation percentage At of the extracted cord is measured in the same manner as the total elongation percentage At of the cord defined above.

[0041] The extraction cord preferably has a diameter D such that D≦6.0 mm, and preferably has a diameter D such that 5.0 mm≦D≦5.5 mm. Diameter D is measured on the cord according to ASTM standard D2969-04.

[0042] The weakening factor Cfrag' takes into account the degree of penetration of the polymer matrix into the cord through the interstrand penetration coefficient Cp. To calculate this penetration coefficient, a saw is used to create cross sections of the extracted cord. This process is repeated 10 times to obtain 10 cross sections, and the average penetration coefficient Cp is calculated across these cross sections. Next, an electron microscope is used to observe the polymer-filled areas of each extracted cord, and image processing software is used to quantify the ratio of the polymer-free non-metallic surface area to the polymer-filled surface area in the contact area Scp between the outer and inner strands, as shown in Figure 8. Thus, a well-permeated cord will have a penetration coefficient close to 1, while a less well-permeated cord will have a penetration coefficient close to 0.5.

[0043] Preferably, the polymeric matrix is ​​an elastomeric matrix.

[0044] The polymeric matrix, which is preferably an elastomeric matrix, is based on a polymeric compound, which is preferably an elastomeric compound.

[0045] A polymeric matrix means a matrix that comprises at least one polymer, and is therefore based on polymeric compounds.

[0046] Elastomeric matrix means a matrix comprising at least one elastomer. Preferred elastomeric matrices are therefore based on elastomeric compounds.

[0047] The expression "based on" is to be understood as meaning that the compound comprises a mixture and / or a product of an in situ reaction of the various components used, some of which can and / or are intended to react at least partially with one another during the various stages of the preparation of the compound, and thus the compound can be fully or partially crosslinked or uncrosslinked.

[0048] By polymeric compound is meant that the compound comprises at least one polymer, which is preferably a thermoplastic, e.g., a polyester or polyamide, a thermoset polymer, an elastomer, e.g., natural rubber, a thermoplastic elastomer, or a combination of these polymers.

[0049] The term "elastomeric compound" means that the compound contains at least one elastomer and at least one other component. The compound containing at least one elastomer and at least one other component preferably contains an elastomer, a crosslinking system, and a filler. Compounds that can be used for these plies are conventional compounds for skim coating filamentous reinforcing elements, preferably containing sulfur, stearic acid, and zinc oxide, and optionally containing vulcanization accelerators and / or retarders and / or various additives; a diene-based elastomer, such as natural rubber; a reinforcing filler, such as carbon black and / or silica; and a crosslinking system, such as a vulcanization system. The adhesion between the metal threads and the matrix in which they are embedded is achieved by a metal coating, such as a brass layer.

[0050] The characteristic values ​​of the extracted cord described in this application are measured on or determined from a cord extracted from a polymeric matrix, particularly an elastomeric matrix, of, for example, a tire. Thus, for example, in a tire, a piece of material radially outside the cord to be extracted is removed so that the cord to be extracted can be seen at the same radial height as the polymeric matrix. This removal can be done by peeling using a cutter and gripper, or by planing. A knife is then used to expose the end of the cord to be extracted. The cord to be extracted is then extracted from the matrix by pulling it at a relatively shallow angle, so as not to plasticize it. Afterwards, the extracted cord is carefully cleaned, for example, using a knife, to sever the remaining polymeric matrix that is locally attached to the cord, while taking care not to damage the surface of the metal threads.

[0051] Extraction code, breaking force: TIFF0007737372000010.tif21153 Advantageously, Fr'≧24,000 N, preferably Fr'≧25,000 N, and even more preferably Fr'≧27,000 N. The breaking force is measured according to ASTM standard D2969-04 on an extraction cord.

[0052] The advantageous features described below apply equally to the codes and extraction codes defined above.

[0053] αf is preferably 0° or more, and more preferably 5° or more.

[0054] αf is preferably 25° or less, and preferably 20° or less.

[0055] In this contact angle range of 0° to 25°, the contact area is maximized and the polymer compound penetrates the cord relatively well.

[0056] αt is preferably 0° or more, and more preferably 5° or more.

[0057] αt is preferably 20° or less, more preferably 15° or less, and even more preferably 10° or less.

[0058] This helix angle range minimizes the contact load between the outer and inner strands when tension is applied to the cord.

[0059] Advantageously, at least 50%, preferably at least 60%, more preferably at least 70%, and very preferably each metal thread of the cord comprises a steel core having a composition according to NF-EN Standard 10020 of September 2000, with a carbon content of C>0.80%, preferably C≧0.82%. Such steel compositions are combinations of non-alloy steels (items 3.2.1 and 4.1 of NF-EN Standard 10020 of September 2000), stainless steels (items 3.2.2 and 4.2 of NF-EN Standard 10020 of September 2000), and other alloy steels (items 3.2.3 and 4.3 of NF-EN Standard 10020 of September 2000). The relatively high carbon content allows achieving a mechanical strength of the metal threads of the cord according to the invention. It would also be possible to modify the manufacturing method of the metal threads to increase their mechanical strength, in particular by further work-hardening each metal thread. While modifying the manufacturing method of the metal thread requires a relatively large industrial investment, the use of a relatively high carbon content does not require such investment. Furthermore, the use of a relatively high carbon content allows the metal thread to maintain its bending and compressive strength, unlike methods that involve further work hardening the metal thread, which significantly reduces its bending and compressive strength.

[0060] Advantageously, at least 50%, preferably at least 60%, more preferably at least 70%, and very preferably each metal thread of the cord comprises a steel core having a composition according to NF-EN standard 10020 of September 2000, with a carbon content C≦1.20%, preferably C≦1.10%. The use of excessively high carbon contents is, on the one hand, relatively expensive and, on the other hand, reduces the corrosion fatigue resistance of the metal thread.

[0061] Preferably, d1, d1', d3, and d3' are independently in the range of 0.25 mm to 0.50 mm, preferably in the range of 0.30 mm to 0.45 mm, and more preferably in the range of 0.32 mm to 0.42 mm.

[0062] Advantageously, the outer layer of the cord is saturated so that the interstrand distance of the outer strands is strictly less than 20 μm.

[0063] 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 the outer strands is defined as the shortest distance that, on average, separates the circular envelopes inscribed in two adjacent outer strands in a cross section of the cord perpendicular to the main axis of the cord. This cord structure therefore ensures good structural stability of the outer layer, and the saturation of the outer layer ensures that the outer layer contains a relatively large number of outer strands and therefore exhibits a relatively high breaking strength.

[0064] The inter-strand distance E is the distance between the two centers of two adjacent outer strands, which are points A and B as shown in FIG. 9, minus the diameter of the outer strands.

[0065] Preferably, the threads of one and the same layer of a given (internal or external) strand all have substantially the same diameter. Advantageously, the external strands all have substantially the same diameter. By "substantially the same diameter" is meant that the threads or strands have the same diameter within industrial tolerances.

[0066] For this purpose, if we consider an orthonormal 2-D reference system, i.e., in the cross section of the cord, the direction of the horizontal axis of which O is the center of the cord, is OA, then in the case where the outer strands all have substantially the same diameter, the coordinates of the centers of the two strands A and B are given by A=[Re TE ,0], B=[Re TE × cos(2π / L), ReTE × sin(2π / L)], where L is the number of external strands and Re TE is the helix radius of each outer strand expressed in millimeters.

[0067] The helical radius of each outer strand is Re TE=max(Re_minTE;ReTEunsaturated), where Re_minTE is the winding radius obtained when the layer is supersaturated. This radius is the minimum radius at which all strands touch: Re_minTE=1 / [(sin 2 (π / L) / D TE / 2) 2 -cos 2 (π / L)×(2π / pe) 2 ], where L is the number of outer strands, pe is the winding pitch of each outer strand in millimeters, DTE is the diameter of the outer strand in mm, and Re TEunsaturated corresponds to unsaturated or strictly saturated structures, and Re TEunsaturated =D TI / 2+D TE / 2, where DTI is the diameter of the inner strand in mm and D TE is the diameter of the outer strand in mm.

[0068] The diameter of the outer strand is D TE = 2 × Re1' + d1' + 2 × d3', where Re1' is the turn radius of the inner layer of the outer strand, - If the inner layer of the outer strand contains only one inner metal thread, Re1'=0; - Otherwise, Re1'=1 / [(sin 2 (π / Q') / d1' / 2) 2 -cos 2 (π / Q')×(2π / p1') 2 ] and where Q' is the number of metal threads in the inner layer of the outer strand, d1' is the diameter in mm of the metal threads in the inner layer of the outer strand, and pitch p1' is the pitch in mm of the inner layer of the outer strand.

[0069] Next, AB=[(xb-xa) 2 +(yb-ya) 2 ] 1 / 2The distance AB in the reference frame is calculated using the formula, and then the interstrand distance is calculated as E=AB-D TE / cos(αt)×1000, and the D TE is the diameter of the outer strands, αt=atan(2πReTE / pe) is the helix angle of the outer strands, and pe is the winding pitch of each outer strand expressed in millimeters.

[0070] In contrast, the unsaturated layer of the cord is such that the interstrand distance of the outer strands is 20 μm or more.

[0071] Advantageously, the outer layer of the inner strand is unsaturated.

[0072] By definition, an unsaturated layer is one in which there is sufficient space between the threads to allow the passage of a polymeric compound, preferably an elastomeric compound. An unsaturated layer means that the threads do not touch each other, and there is sufficient space between two adjacent threads to allow the passage of a polymeric compound, preferably an elastomeric compound. In contrast, a saturated layer is one in which there is not sufficient space between the threads of the layer, for example, because each pair of two threads of the layer is in contact with each other, to allow the passage of a polymeric compound, preferably an elastomeric compound.

[0073] By definition, the interstrand distance of a layer is taken as the shortest distance that separates, on average, two adjacent threads of the layer in a cross section of the cord perpendicular to the major axis of the cord.

[0074] The inter-thread distance for a layer is calculated as follows: The radius of the outer layer of the outer strand is Re3'=Re1'+d1 / 2+d3 / 2 where Re1' is the turn radius of the inner layer of the outer strand as defined above.

[0075] The inter-thread distance I3' is the distance between the two centers of the metal threads as shown in Figure 9 minus the thread diameter, and the calculation method is the same as that used for the outer strands. A'=[Re 3’ ,0] B'=[Re 3’ ×cos(2π / N'),Re3'×sin(2π / N')] A'B'=[(xb'-xa') 2 +(yb'-ya') 2 ] 1 / 2

[0076] This then gives I3' = A'B' - d3' / cos(αC3') × 1000, where αC3' = atan(2πR3' / p3') is the helix angle of the outer layer of the outer strand.

[0077] The total SI3' is the sum of the inter-thread distances separating each pair of adjacent outer threads in the outer layer.

[0078] Advantageously, the interthread distance of the outer layer of the inner strands is 5 μm or more, preferably 15 μm or more, more preferably 35 μm or more, even more preferably 50 μm or more, and most preferably 60 μm or more.

[0079] The distance between the threads in the outer layer of the inner strand is preferably 100 μm or less.

[0080] Advantageously, the sum SI3 of the inter-thread distances I3 of the outer layer of the inner strands is greater than the diameter d3 of the outer threads of the outer layer.

[0081] Advantageously, each strand is of the type that is not rubberized in situ, meaning that each strand is made up of different layers of threads and does not contain any polymeric compounds, in particular elastomeric compounds, before the strands are assembled together.

[0082] Advantageously, the outer layer of each outer strand is unsaturated.

[0083] Advantageously, the interthread distance of the outer layer of each outer strand is 5 μm or more, preferably 15 μm or more, more preferably 35 μm or more, even more preferably 50 μm or more, and most preferably 60 μm or more.

[0084] The inter-thread distance of the outer layer of each outer strand is preferably 100 μm or less.

[0085] Advantageously, the sum SI3' of the inter-thread distances I3' of the outer layers of each outer strand is equal to or greater than the diameter d3' of the outer threads of the outer layer.

[0086] Each inner metal thread of an inner strand preferably has a diameter d1 greater than or equal to the diameter d3 of each outer metal thread of the inner strand, preferably 1.00≦d1 / d3≦1.20.

[0087] Each internal metal thread of each external strand preferably has a diameter d1' that is equal to or greater than the diameter d3' of each external metal thread of each external strand (TE), preferably 1.00≦d1' / d3'≦1.20.

[0088] In one embodiment, each inner thread has a diameter d1 or d1' equal to or greater than the diameter d3 or d3' of each outer thread, respectively. Using diameters such that d1 > d3 or d1' > d3' can facilitate penetration of polymeric compounds, such as elastomeric compounds, through the outer layer. In another embodiment, where d1 = d3 and d1' = d3', the number of different threads that must be managed in the manufacture of the cord can be limited.

[0089] The outer layer of the inner strand preferably contacts and wraps around the inner layer of the inner strand.

[0090] Advantageously, L=6, 7 or 8, preferably L=6 or 7, and even more preferably L=6.

[0091] Preferably, K = 1 and L = 6. In a cord with K = 1, the greatest lateral load is the lateral load exerted by the outer strands on the inner strands.

[0092] Inner strand of the cord according to the invention In one preferred embodiment, Q>1, preferably Q=2, 3 or 4. In cases where Q is equal to 1, there is a risk of seeing the inner threads of the inner strands move radially away from the inner strands and the cord under the effect of repeated compressive loads on the cord. This risk is reduced by the presence of multiple (Q>1) threads in the inner layer of the inner strands, which distributes the compressive load over multiple threads in the inner layer.

[0093] Advantageously, N=7, 8, 9 or 10, preferably N=8 or 9.

[0094] In a first alternative, Q=2 and N=7 or 8, preferably Q=2, N=7.

[0095] In a second alternative, Q=3 and N=7, 8 or 9, preferably Q=3 and N=8.

[0096] In a third alternative, Q=4 and N=7, 8, 9 or 10, with Q=4 and N=9 being preferred.

[0097] It is highly advantageous for each inner thread of an inner strand to have a diameter d1 equal to the diameter d3 of each outer thread of the inner strand.Thus, it is preferred that threads of the same diameter are used in the inner and outer layers of the inner strand, thereby limiting the number of different threads that need to be managed during the manufacture of the cord.

[0098] Outer strand of the cord according to the invention Advantageously, N'=7, 8, 9 or 10, preferably N'=8 or 9.

[0099] In a first alternative, Q'=2 and N'=7 or 8, preferably Q'=2, N'=7.

[0100] In a second alternative, Q'=3 and N'=7, 8 or 9, preferably Q'=3, N'=8.

[0101] In a third alternative, Q'=4 and N'=7, 8, 9 or 10, preferably Q'=4, N'=9.

[0102] It is highly advantageous for each of the inner threads of the outer strands to have a diameter d1' equal to the diameter d3' of each of the outer threads of the outer strands.Thus, it is preferred that threads of the same diameter are used in the inner and outer layers of the inner strands, thereby limiting the number of different threads that need to be managed during the manufacture of the cord.

[0103] Advantageously, Q=4 and N=9, Q'=4 and N'=9, and d1=d3=d1'=d3'.

[0104] Reinforced product according to the present invention Another subject of the invention is a reinforced product comprising a polymeric matrix and at least one cord or extraction cord as defined above.

[0105] The reinforced product comprises one or more cords according to the invention embedded in a polymeric matrix, the cords being advantageously arranged side by side in the main direction in the case of a plurality of cords.

[0106] Tire according to the present invention Another subject of the invention is a tire comprising at least one cord or reinforcing product as defined above.

[0107] Preferably, the tire has a carcass reinforcement fixed in two bead portions, on which radially rests a crown reinforcement connected to said bead portions by two sidewall portions and including at least one cord as defined above, and on which a tread portion rests.

[0108] In one preferred embodiment, the crown reinforcement comprises a working reinforcement comprising at least one cord as defined above, and a protective reinforcement sandwiched radially intermediate the tread portion and the working reinforcement.

[0109] The Code covers, inter alia, "heavy vehicles", i.e. industrial vehicles selected from heavy vehicles such as subways, buses, road vehicles (lorries, tractors, trailers), off-road vehicles, agricultural or plant construction vehicles or other transport or haulage vehicles.

[0110] The tire is preferably for a construction plant type vehicle, and therefore has a size such that the diameter in inches of the rim seat to which the tire is intended to be mounted is 40 inches or greater.

[0111] The present invention also relates to a rubber item comprising an assembly according to the invention or an impregnated assembly according to the invention, by which is meant any type of rubber item such as a ball, a non-pneumatic object such as a non-pneumatic tire casing, a conveyor belt or a catwalk.

[0112] The invention will be better understood on reading the following examples, given purely as non-limiting examples, with reference to the drawings in which: [Brief explanation of the drawings]

[0113] [Figure 1] 1 is a cross-sectional view perpendicular to the circumferential direction of a tire according to the present invention; [Figure 2] FIG. 2 is a detailed view of region II in FIG. 1. [Figure 3]1 is a cross-sectional view of a reinforced product according to the present invention. [Figure 4] 1 is a schematic diagram of a cord (50) according to a first embodiment of the invention in cross section perpendicular to the cord axis (assumed to be straight and stationary). FIG. [Figure 5] 1 is a schematic diagram of an extraction cord (50') according to a first embodiment of the invention, in cross section perpendicular to the axis of the cord (assumed to be straight and stationary). FIG. [Figure 6] 5 is a view similar to that of FIG. 4 of a cord (60) according to a second embodiment of the invention. [Figure 7] FIG. 5 is a schematic diagram of the angle αf of the cord (50) of FIG. 4. [Figure 8] 1 is a photograph of a cord (50) according to a first embodiment of the present invention. [Figure 9] 1 is a schematic diagram of different geometric parameters of a code; DETAILED DESCRIPTION OF THE INVENTION

[0114] Example of a tire according to the present invention 1 and 2 show reference systems X, Y, Z corresponding to the normal axial (X), radial (Y) and circumferential (Z) directions of the tire, respectively.

[0115] The "median circumferential plane" M of the tire is a plane perpendicular to the tire's axis of rotation and equidistant from the annular reinforcing structure of each bead.

[0116] 1 and 2 show a tire according to the present invention, designated by the general reference numeral 10. In FIG.

[0117] The tire 10 is intended for heavy vehicles of the construction plant type, for example of the "dump truck" type, and therefore has dimensions of the 53 / 80R63 type.

[0118] The tire 10 has a crown 12 reinforced by a crown reinforcement 14, two sidewall portions 16, and two bead portions 18, each of which is reinforced by an annular structure, in this case a bead thread 20. A tread portion 22 radially rests on the crown reinforcement 14 and is connected to the bead portions 18 by the sidewall portions 16. A carcass reinforcement 24 is fixed to the two bead portions 18, wrapped around the two bead threads 20 in this case, and includes a turn-up portion 26 arranged towards the outside of the tire 20, here shown mounted on a wheel rim 28. The carcass reinforcement 24 radially rests on the crown reinforcement 14.

[0119] The carcass reinforcement 24 includes 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 portion 18 to the other so as to form an angle of 80° to 90° with the median circumferential plane M (a plane that is located midway between the two bead portions 18, passes through the center of the crown reinforcement 14, and is perpendicular to the tire rotational axis).

[0120] The tire 10 also includes a sealing ply 32 composed of an elastomer (commonly known as an "inner liner") that defines the 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.

[0121] The crown reinforcement 14 includes, from the outside of the tire 10 toward the radially inside of the tire 10, a protective reinforcement 36 arranged radially inside the tread portion 22, a working reinforcement 38 arranged radially inside the protective reinforcement 36, and an additional reinforcement 40 arranged radially inside the working reinforcement 38. Thus, the protective reinforcement 36 is arranged radially intermediate between the tread portion 22 and the working reinforcement 38. The working reinforcement 38 is arranged radially intermediate between the protective reinforcement 36 and the additional reinforcement 40.

[0122] The protective reinforcement 36 includes first and second protective plies 42, 44 containing protective metal cords, the first ply 42 being disposed radially inward of the second ply 44. Optionally, the protective metal cords form an angle with the circumferential direction Z of the tire that is at least equal to 10°, preferably in the range of 10° to 35°, more preferably in the range of 15° to 30°.

[0123] The working reinforcement 38 includes first and second working plies 46, 48, with the first ply 46 disposed radially inward of the second ply 48. Each ply 46, 48 includes at least one cord 50. Optionally, the working metal cord 50 crosses from one working ply to the other and forms an angle with the circumferential direction Z of the tire equal to a maximum of 60°, preferably ranging from 15° to 40°.

[0124] The additional reinforcement 40, also called limiting block and intended to partially absorb the mechanical expansion stresses, comprises, for example, additional metallic reinforcing elements known per se, which form an angle with the circumferential direction Z of the tire 10 equal to a maximum of 10°, preferably ranging from 5° to 10°, as described, for example, in French patent no. 2 419 181 or French patent no. 2 419 182.

[0125] Examples of reinforced products according to the present invention 3 shows a reinforced product according to the present invention, designated by the general reference numeral 100. The reinforced product 100 comprises at least one cord 50, in this example a plurality of cords 50, embedded in a polymeric matrix 102.

[0126] In Figure 3, the polymer matrix 102, the cords 50 are shown in a reference system X, Y, Z, in which direction Y is radial and directions X and Z are axial and circumferential. In Figure 3, the reinforced product 100 comprises a plurality of cords 50 arranged side by side in the main direction X, extending parallel to one another within the reinforced product 100 and collectively embedded in the polymer matrix 102. In this case, the polymer matrix 102 is an elastomeric matrix based on an elastomeric compound.

[0127] Code according to a first embodiment of the present invention FIG. 4 shows a cord 50 according to a first embodiment of the present invention.

[0128] As can be seen with reference to Figure 5, each protective reinforcing element 43, 45 and each hoop reinforcing element 53, 55, once extracted from the tire 10, is formed by an extracted cord 50', which will be described below. The cord 50 is obtained by embedding each of the protective reinforcing elements 43, 45 and each of the hoop reinforcing elements 53, 55 in a polymer matrix, in this case the polymer matrix forming each of the protective plies 42, 44 and each of the hoop layers 52, 54, respectively.

[0129] The cord 50 and extraction cord 50' are made of metal and are of the multi-strand type including two cylindrical layers, and it will be understood that there are therefore no more or less than two layers of strands making up the cord 50 or 50'.

[0130] The cord 50 or cord 50' includes an inner layer CI of cord made up of K≧1 inner strands TI. The outer layer CE is made up of L>1 outer strands TE wound around the inner layer CI of cord. In this particular case, L=6, 7 or 8, preferably L=6 or 7, and more preferably L=6, where L=6.

[0131] Code 50 is the breaking energy per unit area: TIFF0007737372000011.tif41155 It has.

[0132] TIFF0007737372000012.tif21153 is.

[0133] The code 50 also includes a wrapper F (not shown) that consists of a single wrapping thread.

[0134] Extraction Code 50' is the breaking energy per unit area: TIFF0007737372000013.tif48155 It has. To calculate Cp, for example, from the photograph of cord 50' in the composite of Figure 8, software can be used to determine the ratio of the polymer-free non-metallic surface area to the polymer-filled surface area in the contact zone Scp between the outer and inner strands, where the ratio averaged over 10 cross sections is equal to 0.9.

[0135] TIFF0007737372000014.tif21153 is.

[0136] The outer layers of the cords 50 and 50' are saturated, so the interstrand distance E of the outer strands is strictly less than 20 μm, where E=0 μm.

[0137] αf is 0° or more, preferably 5° or more, and 25° or less, preferably 20° or less. Here, αf=18.9°.

[0138] αt is 0° or more, preferably 5° or more, and 20° or less, preferably 15° or less, and more preferably 10° or less. Here, αt=9.1°.

[0139] Cord 50 and 50' inner strand TI Each inner strand TI is a two-layer strand and includes an inner layer C1 made up of Q=2, 3 or 4 inner metal threads F1 and an outer layer C3 made up of N outer metal threads F3 wound around the inner layer C1.

[0140] Here Q=4.

[0141] Advantageously, N=7, 8, 9 or 10, preferably N=8 or 9, where N=9.

[0142] The outer layer C3 of each inner strand TI is desaturated. The inter-thread distance of the outer layer of the inner strand is 15 μm or more, more preferably 35 μm or more, even more preferably 50 μm or more, and very preferably 60 μm or more, here equal to 61 μm. The sum SI3 of the inter-thread distances I3 of the outer layers is greater than the diameter d3 of the outer thread F3 of the outer layer C3. Here, the sum SI3 = 0.061 × 9 = 0.55 mm, which is greater than d3 = 0.40 mm.

[0143] Each inner and outer thread of each inner strand TI has a diameter d1 and a diameter d3, respectively. Each inner metal thread F1 of each inner strand TI has a diameter d1 that is equal to or greater than the diameter d3 of each outer metal thread of each inner strand TI, preferably 1.00≦d1 / d3≦1.20.

[0144] d1 and d3 are independently in the range of 0.25 mm to 0.50 mm, preferably in the range of 0.30 mm to 0.45 mm, and more preferably in the range of 0.32 mm to 0.42 mm, where d1=d3=0.40 mm.

[0145] Outer strand TE of cord 50 and 50' Each outer strand TE has two layers, including an inner layer C1' made up of Q'=2, 3 or 4 inner metal threads F1' and an outer layer C3' made up of N' outer metal threads F3' wound around the inner layer C1'.

[0146] Here, Q'=4.

[0147] N'=7, 8, 9 or 10, preferably N'=8 or 9, where N'=9.

[0148] The outer layer C3' of each outer strand TE is unsaturated. Because the outer layer C3' is unsaturated, the inter-thread distance I3' of the outer layer C3', which separates the N' outer threads on average, is 5 μm or more. The inter-thread distance I3' of the outer layer of each outer strand is 15 μm or more, more preferably 35 μm or more, even more preferably 50 μm or more, and very preferably 60 μm or more, here equal to 61 μm. The sum SI3' of the inter-thread distances I3' of the outer layer C3' is greater than the diameter d3' of the outer thread F3' of the outer layer C3'. Here, the sum SI3' = 0.061 × 9 = 0.55 mm, which is greater than d3' = 0.40 mm.

[0149] Each inner and outer layer C1', C3' of each outer strand TE is wound in the same direction as the winding direction of the cord and the inner and outer layers C1, C3 of the inner strand TI, where the winding direction of each layer of the cord and the winding direction of the cord itself is Z.

[0150] Each inner and outer thread of each outer strand TE has a diameter d1' and a diameter d3', respectively. Each inner metal thread F1' of each outer strand TE has a diameter d1' equal to or greater than the diameter d3' of each outer metal thread F3' of each outer strand TE, preferably 1.00≦d1' / d3'≦1.20.

[0151] d1' and d3' are independently in the range of 0.25 mm to 0.50 mm, preferably in the range of 0.30 mm to 0.45 mm, and more preferably in the range of 0.32 mm to 0.42 mm, where d1'=d3'=0.40 mm.

[0152] The codes 50 and 50' are such that Q=4 and N=9, Q'=4 and N'=9, and d1=d3=d1'=d3', where d1=d3=d1'=d3'=0.40 mm.

[0153] The metal threads of the cord comprise a steel core in which at least 50%, preferably at least 60%, more preferably at least 70%, and very preferably each metal thread has a composition in accordance with NF-EN standard 10020 of September 2000, with a carbon content C>0.80%, preferably C≧0.82%, and the metal threads of the cord comprise a steel core in which at least 50%, preferably at least 60%, more preferably at least 70%, and very preferably each metal thread has a composition in accordance with NF-EN standard 10020 of September 2000, with a carbon content C≦1.20%, preferably C≦1.10%, and wherein each metal thread comprises a steel core in which the composition is in accordance with NF-EN standard 10020 of September 2000, with a carbon content C=1%.

[0154] Each thread has a breaking strength, expressed in Rm, such that 2500≦Rm≦3100 MPa. The steel of these threads is said to be of SHT (“super high tensile”) grade. Other threads can be used, such as lower grade threads, for example NT (“normal tensile”) or HT (“high tensile”) grades, as well as higher grade threads, for example UT (“ultra tensile”) or MT (“mega tensile”) grades.

[0155] Method for manufacturing a cord according to the present invention Next, an example of a method for manufacturing the multi-strand cord 50 will be described.

[0156] Each of the above-mentioned inner strands is preferably carried out continuously in-line. a first step of assembling initially Q=4 internal threads F1 of the inner layer C1 by cable knitting in the Z direction with a pitch p1 to form the inner layer C1 at a first assembly point; a second step of assembling N outer threads F3 around the Q inner threads F1 of the inner layer C1 in the Z direction with a pitch p3 by cable knitting or twisting to form an outer layer C3 at a second assembly point; - preferably a final twist balancing step; The compound is prepared according to known methods, including

[0157] Each of the above-mentioned outer strands is preferably carried out in-line continuously. a first step of assembling initially Q'=2, 3 or 4 internal threads F1' of an internal layer C1' by cable knitting in the Z direction with a pitch p1' to form an internal layer C1' at a first assembly point; a second step of assembling N' outer threads F3' around the Q' inner threads F1' of the inner layer C1' by cable knitting or twisting in the Z direction with a pitch p3' to form an outer layer C3' at a second assembly point; - preferably a final twist balancing step; The compound is prepared according to known methods, including

[0158] As known to those skilled in the art, "twist balancing" herein refers to the elimination of residual torque (or elastic return of twist) on each thread of the strand in the middle layers as well as the outer layers.

[0159] After this final twist balancing step, the strand production is complete, and each strand is wound onto one or more storage reels for storage before the subsequent operation of cable-braiding the elementary strands together to obtain a multi-strand cord.

[0160] To manufacture the multi-strand cord of the present invention, a method well known to those skilled in the art is to cable or twist together pre-obtained strands using a cable or twisting machine rated to assemble strands.

[0161] Thus, L outer strands TE are assembled in the Z direction around the inner strand TI with a pitch pe to form the cord 50. Optionally, in a final assembly step, a wrapper F is wound in the S direction around the assembly already obtained with a pitch pf.

[0162] 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 reinforcing fillers, conventionally used for the manufacture of crown reinforcements in radial tires. Essentially, this compound contains, in addition to the elastomer and reinforcing filler (carbon black), antioxidants, stearic acid, extender oil, cobalt naphthenate as adhesion promoter, and finally a vulcanization system (sulphur, accelerator and ZnO).

[0163] These cord-reinforced composite fabrics have an elastomeric composite matrix formed from two thin layers of elastomeric composite, each 1 mm to 4 mm thick, overlapping each other on either side of the cord. The skim pitch (the spacing between the cords within the elastomeric composite fabric) ranges from 4 mm to 8 mm.

[0164] These composite fabrics are then used as working plies in the crown reinforcement during the manufacturing process of the tire, a step otherwise known to those skilled in the art.

[0165] Code according to a second embodiment of the present invention FIG. 6 shows a cord 60 according to a second embodiment of the present invention.

[0166] Unlike the first embodiment described above, the code 60 according to the second embodiment is such that Q=3 and N=8, and Q'=3 and N'=8.

[0167] Table 1 below summarizes the properties of the various cords 50, 50' and 60.

[0168] [Table 1]

[0169] Comparative Test Evaluation of fracture energy per unit area Various control and prior art cords were simulated.

[0170] Table 2 summarizes the properties of the control code T1 and the code EDT of the prior art (Example 8 of WO 2016 / 017655).

[0171] [Table 2]

[0172] Tables 1 and 2 show that cords 50, 50' and 60 exhibit improved breaking energy per unit area relative to prior art cords EDT and EDT'. Specifically, cords EDT and EDT' have a relatively high weakening factor but a relatively low breaking force, so that the breaking energy per unit area is not sufficient to reduce the number of cord breaks and punctures in tires. Therefore, the cord according to the invention has a breaking energy per unit area ES≧150 N.mm that is high enough to overcome these disadvantages. -1 It has.

[0173] The present invention is not limited to the above-described embodiments. [Explanation of symbols]

[0174] 50 Code CE code outer layer The inner layer of CI code C1 Inner layer of inner strand C1' Inner layer of outer strand C3 Outer layer of inner strand C3' outer layer of outer strand F1 Internal metal thread of the internal strand F1' inner metal thread of outer strand F3 External metal thread on internal strand F3' outer metal thread of outer strand TE Outer Strand TI Internal Strand

Claims

1. A two-layer multi-strand cord (50), an inner layer (CI) of said cord consisting of K=1 inner strand (TI) having two layers (C1, C3), The two layers (C1, C3) are an inner layer (C1) consisting of Q=2, 3 or 4 inner metal threads (F1); an outer layer (C3) consisting of N outer metal threads (F3) of diameter d3 wound around the inner layer (C1); Including, The two-layer multi-strand cord (50) is an outer layer (CE) of the cord consisting of L>1 outer strands (TE) wound around the inner layer (CI) of the cord, the outer layer (CE) having two layers (C1', C3'), The two layers (C1', C3') are an inner layer (C1') consisting of Q'=2, 3 or 4 inner metal threads (F1'); an outer layer (C3) consisting of N' outer metal threads (F3') of diameter d3' wound around the inner layer (C1'); Including, The cord (50) has a breaking energy per unit area ES≧155 N.mm -1 and where: is the total breaking force in Newtons of Nc threads, Nc=Q+N+L×(Q′+N′) is the total number of metal threads; D is the diameter of the cord in mm, is the sum of the total elongation rates of the Nc threads and is dimensionless; Cfrag is the dimensionless weakening coefficient of the cord (50), where: d3 and d3' are expressed in mm; αf is the contact angle between the outer metal thread (F3) of the inner strand (TI) and the outer metal thread (F3′) of the outer strand (TE), expressed in radians; αt is the helix angle of each outer strand (TE) expressed in radians; Cste=1500N. mm -2 and Each thread has a breaking strength, in Rm, such that 2500≦Rm≦3100 MPa. A code (50) characterized in that

2. ES≧160N. mm -1 That is, The cord (50) of claim 1.

3. Breaking force such that Fr≧25,000 N: Showing, The cord (50) of claim 1.

4. An extraction cord (50') extracted from a polymer matrix, an inner layer (CI) of said cord consisting of K=1 inner strand (TI) having two layers (C1, C3), The two layers (C1, C3) are an inner layer (C1) consisting of Q=2, 3 or 4 inner metal threads (F1); an outer layer (C3) consisting of N outer metal threads (F3) of diameter d3 wound around the inner layer (C1); Including, The extraction code (50') an outer layer (CE) of the cord consisting of L>1 outer strands (TE) wound around the inner layer (CI) of the cord, the outer layer (CE) having two layers (C1', C3'), The two layers (C1', C3') are an inner layer (C1') consisting of Q'=2, 3 or 4 inner metal threads (F1'); an outer layer (C3) consisting of N' outer metal threads (F3') of diameter d3' wound around the inner layer (C1'); Including, The extraction cord (50') has a breaking energy ES'≧150 N.mm -1 and where: is the total breaking force in Newtons of Nc threads, Nc=Q+N+L×(Q′+N′) is the total number of metal threads; D is the diameter of the cord in mm, is the sum of the total elongation rates of the Nc threads and is dimensionless; Cfrag' is the dimensionless weakening factor of the cord (50'), where: Cp is the permeability coefficient of the cord; d3 and d3' are expressed in mm; αf is the contact angle between the outer metal thread (F3) of the inner strand (TI) and the outer metal thread (F3′) of the outer strand (TE), expressed in radians; αt is the helix angle of the outer strand (TE) expressed in radians; Cste=1500N. mm -2 and Each thread has a breaking strength, in Rm, such that 2500≦Rm≦3100 MPa. A cord (50') characterized in that

5. The cord (50, 50') according to claim 1 or 4, wherein αf is equal to or greater than 0° and αf is equal to or less than 25°.

6. αt is greater than or equal to 0° and αt is less than or equal to 20°; A cord (50, 50') according to claim 1 or 4.

7. The outer layer (C3) of the inner strand (TI) is unsaturated. A cord (50, 50') according to claim 1 or 4.

8. The outer layer C3' of each outer strand (TE) is unsaturated; A cord (50, 50') according to claim 1 or 4.

9. a polymer matrix (102) and at least one extraction code (50') according to claim 4, A reinforced product (100) characterized in that:

10. 10. The reinforcement product according to claim 9, comprising at least one extraction cord (50') according to claim 4. A tire (10) characterized in that

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