REINFORCED FABRIC WITH A VARIETY OF METAL REINFORCEMENT ELEMENTS

Description

Technical field of the invention

[0001] The present invention relates to the field of reinforced fabrics, in particular reinforced fabrics used in pneumatic tires, as well as to the field of pneumatic tires. Prior art

[0002] A pneumatic tire with a radial carcass reinforcement for a passenger vehicle or light truck comprises, as we know, a tread, two inextensible beads, two flexible sidewalls connecting the beads to the tread and a rigid crown reinforcement, or "belt", arranged circumferentially between the carcass reinforcement and the tread.

[0003] The crown reinforcement comprises several reinforced fabrics, called plies, and is generally made up of at least two rubber plies called "working plies", "triangulation plies" or "working reinforcements", superimposed and crossed, most often reinforced with metal cables arranged substantially parallel to each other and inclined relative to the median circumferential plane of the tire, and a rubber ply located above the working plies (tread side), called "friction ply" or "friction reinforcement", which is generally reinforced by reinforcing threads called "circumferential" and whose primary function is to resist centrifugation of the crown at high speed. These plies may or may not be associated with other plies and / or rubber fabrics.The primary function of the working plies is to give the tire a high level of stiffness or drift thrust (in English, "drift thrust" or "cornering"), which is known to be necessary for obtaining good handling on a motor vehicle.

[0004] Such belt structures, ultimately consisting of a multi-layer composite laminate comprising at least one hooping layer, most often textile, and two generally metallic working layers, are well known to those skilled in the art and do not need to be described here in more detail. Such belt structures are illustrated for example by documents US 4,371,025 and FR 2,504,067.

[0005] The availability of increasingly strong and durable steels means that tire manufacturers are now moving, as far as possible, towards using very simple structured cables in tire belts, particularly with only two wires, or even single filaments, in order on the one hand to simplify manufacturing and reduce costs, on the other hand to reduce the thickness of the reinforcement plies and thus the hysteresis of the tires and, ultimately, to reduce the energy consumption of vehicles equipped with such tires.

[0006] However, efforts to reduce the mass of tires, particularly by reducing the thickness of their belt and the rubber layers constituting it, naturally come up against physical limits which can give rise to a certain number of difficulties. In particular, it may happen that the hooping function provided by the hooping reinforcement and the stiffening function provided by the working reinforcement are no longer sufficiently differentiated from each other and may disrupt each other. This is detrimental to the proper functioning of the crown of the tire, to the performance and overall endurance of the tire.

[0007] Thus, patent applications WO 2013 / 117476 and WO 2013 / 117477 proposed a multi-layer composite laminate with a specific structure that makes it possible to significantly lighten the tire belt, and therefore lower its rolling resistance, while overcoming the drawbacks mentioned above, consisting of a textile hoop ply and two working plies comprising metal monofilaments. Application WO2019 / 020888 aims to further reduce the mass of the plies while improving buckling resistance, by linking the diameter of the metal monofilaments, the density of said monofilaments and the thickness of the ply.

[0008] Other work, such as for example that set out in application JP2001 / 328407, has focused on the use of metal reinforcement elements whose cross-section is no longer circular, but inscribed in a rectangle in order, in particular, to refine the plies, thus leading to their lightening and inducing a reduction in the rolling resistance of the tire. Document JP2017 / 048351 teaches the use of a flat reinforcement whose height to width ratio is preferably between 0.4 and 0.5 with an intercable, i.e. the distance between two consecutive reinforcement elements, between 0.15 and 0.54 mm, associated with a specific elastomeric composition in order to lower rolling resistance, limit heating problems and avoid ply separation problems.

[0009] However, the heavier weight of vehicles and their increased performance lead, among other things, to an increase in the breaking strength of the plies. This strength can be increased, for example, by increasing the mechanical strength of the metal reinforcements, with limits inherent in the availability of steels, or by increasing their diameter and / or the density of these reinforcements, which can lead to an increase in the thickness of the plies and / or their mass, thus increasing the weight of the tire and / or reducing the space separating two consecutive metal reinforcement elements within a ply. It then becomes difficult to feed the rubber bridges located between the reinforcement elements, which can harm the endurance of the ply(ies) and therefore of the tire, in particular due to the risk of cleavage, which corresponds to the appearance of cracks propagating between the working plies.Reducing the intercable can also make the fabrication of the layers difficult, by requiring many metal wires to be placed in parallel and at a short distance from each other.

[0010] Continuing its research, the applicant discovered a specific configuration of fabric reinforced by metallic reinforcing elements having very good breaking strength, lower rolling resistance and sufficient intercable to avoid possible cleavage problems compared to the reinforced fabrics of the state of the art. Detailed description of the invention Definitions

[0011] Main direction means the direction in which the largest dimension of a metal reinforcing element extends, coincident with the axis of this reinforcing element.

[0012] By transverse direction we mean a direction perpendicular to the main direction.

[0013] By substantially is meant within the limits of mechanical tolerances or measurement methods.

[0014] The carbon-containing compounds mentioned in the description may be of fossil origin or bio-sourced. In the latter case, they may be, partially or totally, derived from biomass or obtained from renewable raw materials derived from biomass. This includes, in particular, polymers, plasticizers, fillers, etc. Reinforced fabric

[0015] The invention relates to a reinforced fabric comprising a plurality of metal reinforcing elements substantially parallel to each other and extending in a main direction, arranged in a transverse direction perpendicular to the main direction at a laying pitch p expressed in mm, embedded in an elastomeric composition based on at least one elastomer, a reinforcing filler, a crosslinking system, each metal reinforcing element having, in a plane perpendicular to the main direction, a transverse section inscribed in a rectangle of length W and height T and having a breaking strength RF expressed in MPa and measured according to the ISO 6892 standard of 1984, said fabric having a breaking force expressed in N / mm equal to R n , in which the laying pitch of the metal reinforcing elements is p≥ 0.8. RF / R n .(a-1+π / 4).T 2< , with a=W / T and 1 / a ranging from 0.35 to 0.75.

[0016] It appeared that such characteristics made it possible to correctly feed the rubber bridge between two consecutive reinforcing elements while lightening the reinforced fabric compared to reinforced fabrics of the prior art, while retaining particularly interesting properties of resistance to rupture and so-called "on-field" and so-called "out-of-plane" rigidity.

[0017] In a manner known to those skilled in the art, the laying pitch is defined as the distance between the geometric centers of two immediately adjacent metal reinforcement elements, measured in the transverse direction.

[0018] Preferably, the laying pitch p is such that p≤ 1.2. RF / R n .(a-1+π / 4).T 2< . Indeed, when the pitch becomes too large, the cooperation between the juxtaposed metal reinforcing elements becomes less good when the fabric is used as a working ply in a pneumatic tire.

[0019] Very preferably, the laying step p is such that 0.9. RF / R n .(a-1+π / 4).T 2< ≤p≤ 1.1. RF / R n .(a-1+π / 4).T 2< . Reinforcing element

[0020] Each reinforcing element is metallic. Preferably, the reinforcing element comprises a steel core coated with a layer of metallic coating made of a metal other than steel in order to improve, for example, the processing properties of the reinforcing element, or the usage properties of the reinforcing element and / or the bandage, such as the adhesion properties, corrosion resistance or even resistance to aging. For example, the metal of the layer of metallic coating is chosen from zinc, copper, tin and alloys of these metals. Examples of alloys of these metals include brass and bronze.

[0021] Steel can have a pearlitic, ferritic, austenitic, bainitic, martensitic microstructure or a microstructure resulting from a mixture of these microstructures.

[0022] According to a preferred embodiment, when a carbon steel is used, its carbon content (% by weight of steel) is in a range from 0.2% to 1.2%; according to another preferred embodiment, the carbon content of the steel is in a range from 0.6% to 0.8%.

[0023] The invention applies in particular to steels of the high-strength steel cord type (known as "HT" for "High Tensile"), preferably very high-strength (known as "SHT" for "Super High Tensile"), or even ultra-high-strength (known as "UHT" for "Ultra High Tensile"), the reinforcing elements then having a tensile strength (RF) which is preferably greater than or equal to 3650-2000.D, where D, expressed in mm, is equal to (T+W) / 2, more preferably greater than or equal to 4000-2000.D, and more preferably greater than or equal to 4350-2000.D. The total elongation at break (At) of these reinforcements, the sum of the elastic elongation and the plastic elongation, is preferably greater than 2.0%.

[0024] Preferably, each reinforcing element has an elastic torsional deformation C, expressed as an absolute value, less than or equal to 6 turns per 6 m of metal reinforcement, preferably less than or equal to 3 turns per 6 m of metal reinforcement.

[0025] This low elastic deformation makes it possible to obtain a fabric that is sufficiently flat to be easily incorporated into a rubber article, in particular a pneumatic tire. In a preferred arrangement, the reinforcing elements may be arranged in the fabric so as to alternate their elastic deformations, as taught in document WO2017 / 203119.

[0026] Each metal reinforcement element has a cross-section, in a plane perpendicular to the main direction, inscribed in a rectangle of length W and height T.

[0027] Such a reinforcing element is, in itself, well known in the state of the art and described for example in documents JP2001 / 328407 and DE102015209343. This reinforcing element can be obtained for example by wire drawing, using dies of substantially rectangular shape, the corners being able to be rounded, or by crushing by passing through a rolling mill a metallic reinforcing element of circular section.

[0028] Each metal reinforcing element of the fabric according to the invention preferably has a ratio 1 / a, representing the ratio of its height, or thickness, T to its width W ranging from 0.35 to 0.65, preferably ranging from 0.45 to 0.65. Such a preferred ratio makes it possible to significantly increase the so-called "on-field" rigidity, i.e. in the axial direction of a pneumatic tire comprising such a fabric as a working ply, while not substantially modifying the so-called "out-of-plane" rigidity, i.e. in the radial direction of a pneumatic tire comprising such a fabric as a working ply, a lower out-of-plane rigidity allowing better "flattening" of the pneumatic tire on horizontal ground.

[0029] Preferably, each metal reinforcing element has a height, or thickness, T ranging from 0.15 to 0.70 mm, preferably from 0.15 to 0.40 mm, very preferably from 0.20 to 0.30 mm. Such a thickness, combined with the other characteristics of the metal reinforcing element, makes it possible to obtain a good compromise between the total thickness of the working ply and its breaking strength.

[0030] The reinforced fabric preferably has a breaking strength R n greater than or equal to 220 N / mm, preferably greater than or equal to 300 N / mm, preferably between 330 and 470 N / mm. Such breaking strengths are particularly advantageous when the fabric according to the invention is used in a pneumatic tire intended to support relatively heavy loads, such as modern passenger vehicles, in particular vehicles of the “Sport Utility Vehicles” type, or vans.

[0031] The total thickness of the reinforced fabric is equal to the thickness of the metal reinforcing element to which are added the thicknesses of rubber located on either side of the reinforcing element, called "thickness on the back", measured in a radial direction, perpendicular to the plane formed by the transverse and main directions. These two thicknesses on the back, on either side of the reinforcement, may be identical or different, and are noted "edos_1" and "edos_2". Thus, the total thickness of the reinforced fabric measured in the radial direction is expressed as edos_1 + T + edos_2. In the particular arrangement where edos_1 = edos_2, the thickness of rubber on the back of the reinforcement is then simply noted "edos" and the total thickness of the reinforced fabric measured in the radial direction is equal to T + 2.edos.

[0032] The thinner the fabric thickness, the lower the hysteresis and therefore the lower the rolling resistance of a tire comprising such a fabric. The rubber bridges between the metal reinforcing elements allow the forces exerted on the or each ply to be correctly absorbed. However, too thin a fabric thickness presents a significant risk of having imperfectly formed rubber bridges and therefore poor absorption of the forces of the fabric(s) when it(they) is(are) used as working ply(ies) of a tire. On the other hand, in a tire, too thin a fabric thickness presents the risk of bringing the metal reinforcing elements closer to the fabric located radially outside the hoop reinforcement.

[0033] Thus, preferably, the reinforced fabric according to the invention has, on either side of the metal reinforcing elements, thicknesses of rubber on the back of the metal reinforcing elements, denoted respectively "edos_1" and "edos_2", measured in a radial direction, perpendicular to the plane formed by the transverse and main directions, such that edos_1 and edos_2 range independently of one another from 0.10 to 0.40 mm, preferably from 0.10 to 0.25 mm, very preferably from 0.15 to 0.22 mm. Elastomeric composition

[0034] The reinforcing elements are embedded in an elastomeric composition, embedded being understood as “totally coated”, with the possible exception of the fabric cutting planes.

[0035] By elastomeric composition is meant a composition with elastomeric behavior. Such a composition is advantageously based on at least one elastomer and one other constituent.

[0036] Preferably, the elastomer is a diene elastomer, that is to say, as a reminder, any elastomer (single elastomer or mixture of elastomers) which is derived, at least in part (i.e., a homopolymer or a copolymer), from diene monomers, that is to say from monomers carrying two carbon-carbon double bonds, whether the latter are conjugated or not.

[0037] This diene elastomer is more preferably chosen from the group consisting of polybutadienes (BR), natural rubber (NR), synthetic polyisoprenes (IR), butadiene copolymers, isoprene copolymers, and mixtures of these elastomers, such copolymers being in particular chosen from the group consisting of butadiene-styrene copolymers (SBR), isoprene-butadiene copolymers (BIR), isoprene-styrene copolymers (SIR) and isoprene-butadiene-styrene copolymers (SBIR).

[0038] A particularly preferred embodiment consists of using an "isoprenic" elastomer, that is to say a homopolymer or a copolymer of isoprene, in other words a diene elastomer chosen from the group consisting of natural rubber (NR), synthetic polyisoprenes (IR), the different copolymers of isoprene and the mixtures of these elastomers.

[0039] The elastomeric composition may comprise one or more diene elastomer(s), also all or part of the additives usually used in compositions intended for the manufacture of bandages, such as for example reinforcing fillers like carbon black or silica, coupling agents, anti-aging agents, antioxidants, plasticizing agents or extending oils, whether the latter are of aromatic or non-aromatic nature (in particular very weakly or non-aromatic oils, for example of the naphthenic or paraffinic type, with high or preferably low viscosity, MES or TDAE oils), plasticizing resins with a high glass transition temperature (above 30°C), agents facilitating the implementation (processability) of the compositions in the raw state, tackifying resins, anti-reversion agents,methylene acceptors and donors such as, for example, HMT (hexamethylenetetramine) or H3M (hexamethoxymethylmelamine), reinforcing resins (such as resorcinol or bismaleimide), known adhesion promoting systems of the metal salt type, for example, in particular cobalt, nickel or lanthanide salts, a crosslinking or vulcanization system.,

[0040] Preferably, the crosslinking system of the elastomeric composition is a so-called vulcanization system, i.e. based on sulfur (or a sulfur-donating agent) and a primary vulcanization accelerator. Various known secondary accelerators or vulcanization activators may be added to this basic vulcanization system. The sulfur is used at a preferred rate of between 0.5 and 10 phr, the primary vulcanization accelerator, for example a sulfenamide, is used at a preferred rate of between 0.5 and 10 phr. The rate of reinforcing filler, for example carbon black and / or silica, is preferably greater than 30 phr, in particular between 30 and 100 phr. By phr is meant parts by weight per hundred parts of elastomer.

[0041] Suitable carbon blacks are all carbon blacks, in particular HAF, ISAF, SAF type blacks conventionally used in tires (so-called tire grade blacks). Among the latter, we will mention in particular carbon blacks of grade (ASTM) 300, 600 or 700 (for example N326, N330, N347, N375, N683, N772). Suitable silicas are in particular precipitated or pyrogenic silicas having a BET surface area of ​​less than 450 m2 / g, preferably 30 to 400 m2 / g.

[0042] Those skilled in the art will know, in light of the present description, how to adjust the formulation of the rubber compositions in order to achieve the desired property levels (in particular modulus of elasticity), and adapt the formulation to the specific application envisaged.

[0043] Preferably, the elastomeric composition has, in the crosslinked state, a secant modulus in extension, at 10% elongation, which is between 4 and 25 MPa, more preferably between 4 and 20 MPa; values ​​in particular between 5 and 15 MPa have proven to be particularly suitable. The modulus measurements are carried out in tension, unless otherwise indicated according to standard ASTM D 412 of 1998 (test piece "C"): the "true" secant modulus (i.e., reduced to the actual section of the test piece) at 10% elongation is measured in second elongation (i.e., after an accommodation cycle), noted here Ms and expressed in MPa (normal temperature and humidity conditions according to standard ASTM D 1349 of 1999). Pneumatic tire

[0044] The invention also relates to a pneumatic tire comprising a crown comprising a tread, two sidewalls, two beads, each sidewall connecting each bead to the crown, a carcass reinforcement anchored in each of the beads and extending in the sidewalls and in the crown, a crown reinforcement extending in the crown in the circumferential direction and located radially between the carcass reinforcement and the tread, the crown reinforcement comprising a working reinforcement comprising at least first and second working plies, in which at least one working ply is a reinforced fabric according to the invention.

[0045] Axial direction means the direction substantially parallel to the axis of rotation of the tire.

[0046] By circumferential direction is meant the direction which is substantially perpendicular to both the axial direction and a radius of the tire (in other words, tangent to a circle whose center is on the axis of rotation of the tire).

[0047] By radial direction is meant the direction along a radius of the tire, that is to say any direction intersecting the axis of rotation of the tire and substantially perpendicular to this axis.

[0048] By median circumferential plane (noted M), we mean the plane perpendicular to the axis of rotation of the tire which is located midway between the two beads and passes through the middle of the crown reinforcement.

[0049] In a preferred embodiment, the reinforcing elements of a first working ply form an angle ranging from 10 to 45 degrees with the circumferential direction.

[0050] In a preferred embodiment, the reinforcing elements of a second working ply form an angle ranging from 10 to 45 degrees with the circumferential direction.

[0051] Advantageously, the reinforcing elements of the first and second working plies are crossed between the first working ply and the second working ply. Thus, if the angle made by the reinforcing elements of the first working ply with the circumferential direction is positive, the angle made by the reinforcing elements of the second working ply with this same circumferential direction is negative. Conversely, if the angle made by the reinforcing elements of the first working ply with the circumferential direction is negative, the angle made by the reinforcing elements of the second working ply with this same circumferential direction is positive.

[0052] In a preferred embodiment, the angle that the reinforcing elements of the first working ply make with the circumferential direction is, in absolute value, substantially equal to the angle that the reinforcing elements of the second working ply make with this same circumferential direction.

[0053] Preferably, each of the two working layers is made of a reinforced fabric according to the invention.

[0054] Preferably, the bandage further comprises a hoop reinforcement comprising at least one hoop ply comprising textile reinforcing elements arranged substantially parallel to each other in the hoop ply. Preferably, these textile reinforcing elements are embedded in an elastomeric composition. The hoop ply is preferably located between the radially outermost working ply and the tread.

[0055] Textile reinforcing elements can have any known shape, they can certainly be monofilaments but most often they are made of multifilament fibers twisted together in the form of textile ropes.

[0056] Preferably, the textile reinforcing elements form an angle at most equal to 10°, preferably ranging from 5° to 10° with the circumferential direction.

[0057] Preferably, the textile reinforcing elements are heat-shrinkable. This means that with an increase in temperature, the material constituting the textile reinforcing elements shrinks. The thermal contraction CT of the textile reinforcing elements, measured after 2 min at 185°C, is advantageously less than 7.5% under the test conditions set out below and preferably less than 3.5%, more preferably less than 3%, values ​​which have proven to be optimal for the stability of manufacturing and sizing of the tires, in particular during the curing and cooling phases of the latter. The CT quantity is measured, unless otherwise specified, according to the ASTM D1204-08 standard, for example on a “TESTRITE” type device, under a so-called standard pre-tension of 0.5 cN / tex (therefore reduced to the linear density or count of the sample tested).At constant length, the maximum contraction force (denoted FC) is also measured using the above test, this time at a temperature of 180°C and under 3% elongation. This contraction force FC is preferably greater than 20 N (Newton). A high contraction force has proven particularly favorable to the hooping capacity of heat-shrinkable textile reinforcement elements, with respect to the crown reinforcement of the tire when the latter heats up under high rolling speed.

[0058] The above CT and FC quantities can be measured indiscriminately on the initial textile reinforcement elements glued before their incorporation into the ply and the bandage, or measured on these reinforcement elements once extracted from the central zone of the vulcanized bandage and preferably “degummed” (i.e. freed from the elastomer composition in which they are embedded).

[0059] Any heat-shrinkable textile material that meets the CT contraction characteristics set out above is suitable. Preferably, this heat-shrinkable textile material is chosen from the group consisting of polyamides, polyesters and polyketones. Among the polyamides, mention may be made in particular of polyamides 4-6, 6, 6-6, 11 or 12. Among the polyesters, mention may be made, for example, of PET (polyethylene terephthalate), PEN (polyethylene naphthalate), PBT (polybutylene terephthalate), PBN (polybutylene naphthalate), PPT (polypropylene terephthalate), PPN (polypropylene naphthalate). Also usable, provided that they meet the recommended CT characteristic, are hybrid reinforcements made of two (at least two) different materials such as, for example, aramid / nylon, aramid / polyester, aramid / polyketone hybrid cords.

[0060] In the reinforced fabric according to the invention, the various geometric characteristics such as the thicknesses edos_1 and edos_2, laying pitch p, length W, height T are measured in a central part of the fabric in the raw state, i.e. unvulcanized, over a total axial width of 4 cm, by calculating an average over all the reinforcing elements present.

[0061] In the pneumatic tire according to the invention, the various geometric characteristics such as the thicknesses edos_1 and edos_2, laying pitch p, length W, height T are measured in the central part of the crown reinforcement of the tire in the vulcanized state, on either side of the median plane M over a total axial width of 4 cm, by calculating an average over all the reinforcing elements present in the central part of the working reinforcement, in an axial interval extending between - 2 cm and + 2 cm relative to the median plane M. Description of figures

[0062] [ Fig 1 ] There figure 1 represents a schematic view of a portion of reinforced fabric according to the invention. In this figure are represented, in a section plane perpendicular to the main direction of the metal reinforcing elements, three reinforcing elements of width W and height or thickness T, these elements being juxtaposed according to a laying pitch p and embedded in an elastomeric composition such that the fabric has on either side of each reinforcing element in the radial direction a thickness of rubber noted respectively "edos_1" and "edos_2". Measurement methods

[0063] The absolute breaking strength of a sheet, expressed in N, is measured by multiplying the number of reinforcing elements present over a 10 cm length of the sheet in the transverse direction by the unit breaking strength of each reinforcing element. The measurements of breaking strength, breaking resistance noted RF (in MPa) and elongation at break noted At (total elongation in %) are carried out in tension according to the ISO 6892 standard of 1984.

[0064] The breaking strength of the web is obtained by dividing the absolute breaking strength of the web determined in the manner indicated above by 100, and is expressed in N / mm.

[0065] The elastic torsional deformation is measured over a given length of metal reinforcement element, for example a length ranging from 5 to 10 m, and the value found is reduced to 6 m in order to obtain the value C. To do this, a very long table is provided, the length of the table being at least equal to the length of metal reinforcement for which the elastic torsional deformation is being measured, and one end of the metal reinforcement is fixed to one end of the table. The metal reinforcement is unrolled, taking care to hold the metal reinforcement to prevent it from rotating on itself around its main axis. At the other end, the metal reinforcement is hung over the edge of the table and a rod is fixed to its end perpendicular to the main axis of the metal reinforcement. Then, the hanging end of the metal reinforcement is left free to rotate. The number of turns the rod makes is then measured.If the rod makes an incomplete turn, the angle made during this turn is related to the non-integer value of this turn. Thus, for an angle of 180°, we will have 0.5 turns.

[0066] The bending stiffness is estimated, for a circular cross-section reinforcement element, by the equation Yd 4< / 64, where d represents the diameter of the circular cross-section reinforcement element and Y represents the Young's modulus of this element. A circular cross-section reinforcement element has by construction the same bending stiffness on fields and out of plane.

[0067] The bending stiffness is estimated, for a reinforcement element of length W and height T by the equation YTW 3< / 12 for the bending stiffness on fields and YWT 3< / 12 for the out-of-plane bending stiffness, where Y represents the Young's modulus of this element. Examples

[0068] The following tests show the advantages of the reinforced fabrics in accordance with the invention.

[0069] Fabrics T1 and T3 correspond to state-of-the-art fabrics using single metal monofilaments as reinforcing elements, with a diameter of 0.32 mm in the case of T1, and a diameter of 0.35 mm in the case of T2. Fabric T2 corresponds to a fabric having the same thickness as the fabric conforming to C1.

[0070] Fabrics C1 and T1 on the one hand, and C3 and T3 on the other, have the same intercable distance. Fabric T2 has the same thickness as fabric C1. Fabric C2 has the same mass, per 1 m 2 < of fabric, as fabric T2. Fabric C4 includes the same metal reinforcing elements as fabric C3 and the same ply strength as fabric T3.

[0071] Regarding mass, the results are given on a base of 100 relative to fabric T1 for fabrics C1, T2 and C2, and relative to fabric T3 for fabrics C3 and C4. A value greater than 100 means that the fabric has a mass greater than the mass of the reference fabric and a value less than 100 means that the fabric has a mass less than the mass of the reference fabric. A higher fabric mass induces a higher rolling resistance of a tire comprising such a fabric. [Table 1] T1 C1 T2 C2 T3 C3 C4 Width W (mm) 0.32 0.42 0.25 0.53 0.35 0.5 0.6 Height T (mm) 0.32 0.25 0.25 0.21 0.35 0.3 0.3 1 / a = T / W 1.00 0.60 1.00 0.40 1.00 0.50 0.50 Breaking force Rn (N / mm) 350 350 350 350 350 437.5 350 No pose p (mm) 0.79 0.89 0.50 0.97 0.93 1.17 1.47 Intercable (mm) 0.47 0.47 0.25 0.44 0.58 0.57 0.87 Fabric thickness (mm) 0.72 0.65 0.65 0.61 0.75 0.7 0.7 Implementation in pneumatic tires - Base 100 Out-of-plane bending stiffness 100 94 59 65 100 145 116 Bending stiffness on fields 100 261 59 403 100 581 465 Rolling resistance 100 95 93 93 100 110 99

Claims

1. A reinforced fabric comprising a plurality of substantially parallel metal reinforcing elements extending in a main direction, arranged in a transverse direction perpendicular to the main direction at a laying pitch p expressed in mm, embedded in an elastomer composition based on at least one elastomer, a reinforcing filler, and a crosslinking system, each metal reinforcing element having, in a plane perpendicular to the main direction, a cross-section inscribed in a rectangle of length W and height T and having a breaking strength RF expressed in MPa and measured in accordance with ISO 6892:1984, said fabric having a breaking force expressed in N / mm equal to Rn, wherein the laying pitch of the metal reinforcing elements is p≥ 0.

8. RF / Rn.(a-1+π / 4).T2, where a=W / T and 1 / a ranges from 0.35 to 0.75.

2. The reinforced fabric as claimed in the preceding claim, wherein the ratio 1 / a ranges from 0.35 to 0.65, preferably from 0.45 to 0.65.

3. The reinforced fabric as claimed in any of the preceding claims, wherein the height T ranges from 0.15 mm to 0.70 mm, preferably from 0.15 to 0.40 mm, and more preferably from 0.20 to 0.30 mm.

4. The reinforced fabric as claimed in any one of the preceding claims, wherein the laying pitch p is such that p≤ 1.

2. RF / Rn.(a-1+π / 4).T2.

5. The reinforced fabric as claimed in any one of the preceding claims, wherein each metal reinforcing element is at least high tensile grade, that is, having a breaking strength RF greater than or equal to 3,650-2,000.D, where D, expressed in mm, is equal to (T+W) / 2.

6. The reinforced fabric as claimed in any one of the preceding claims, wherein each metal reinforcing element is at least super high tensile grade, that is, having a breaking strength RF greater than or equal to 4,000-2,000.D, where D, expressed in mm, is equal to (T+W) / 2.

7. The reinforced fabric as claimed in any one of the preceding claims, wherein each metal reinforcing element is at least ultra high tensile grade, that is, having a breaking strength RF greater than or equal to 4,350-2,000.D, where D, expressed in mm, is equal to (T+W) / 2.

8. The reinforced fabric as claimed in any one of the preceding claims, having, on either side of the metal reinforcing elements, rubber thicknesses on the back of the metal reinforcing elements, respectively denoted "edos_1" and "edos_2", measured in a radial direction perpendicular to the plane formed by the transverse and main directions, such that edos_1 and edos_2 range independently of each other from 0.10 to 0.40 mm, preferably 0.10 to 0.25 mm, and more preferably 0.15 to 0.22 mm.

9. The reinforced fabric as claimed in any one of the preceding claims, wherein each reinforcing element comprises a steel core covered with a metal coating layer made from a metal other than steel.

10. The reinforced fabric as claimed in any one of the preceding claims, wherein each reinforcing element has a torsional elastic deformation C, expressed as an absolute value, less than or equal to 6 turns per 6 m of metal reinforcer, preferably less than or equal to 3 turns per 6 m of metal reinforcer.

11. The reinforced fabric as claimed in any one of the preceding claims, wherein Rn is greater than or equal to 220 N / mm, preferably greater than or equal to 300 N / mm, more preferably between 330 and 470 N / mm.

12. The reinforced fabric as claimed in any one of the preceding claims, wherein the elastomer of the elastomer composition is a diene elastomer, preferably an isoprene elastomer.

13. A pneumatic tire comprising a crown comprising a tread, two sidewalls, and two beads, each sidewall connecting each bead to the crown, a carcass reinforcement anchored in each of the beads and extending in the sidewalls and in the crown, a crown reinforcement extending in the crown in the circumferential direction and situated radially between the carcass reinforcement and the tread, the crown reinforcement comprising a working reinforcement comprising at least first and second working plies, wherein at least one working ply is a reinforced fabric as claimed in any one of the preceding claims.

14. The pneumatic tire as claimed in the preceding claim, wherein each first and second working ply consists of a reinforced fabric as claimed in any one of claims 1 to 12.

15. The pneumatic tire as claimed in any one of the preceding claims, comprising a hoop reinforcement comprising at least one hooping ply comprising textile reinforcing elements arranged substantially parallel to each other in the hooping ply.