Reinforcing element and method for manufacturing such a reinforcing element

Abstract

A reinforcing element (50; 50'; 50'') comprising an assembly of at least two monofilaments (52), the monofilaments (52) each comprising at least one glass fibre and a cross-linked resin coating the glass fibre, the monofilaments (52) being assembled together by being wound helically along an axis of extension (A-A) of the reinforcing element (50; 50'; 50'').

Description

[0001] DESCRIPTION

[0002] TITLE: Reinforcing element and method of manufacturing such a reinforcing element

[0003] Technical field

[0004] The present invention relates to the field of reinforcements based on composite materials.

[0005] More specifically, the invention relates to a reinforcing element and a method of manufacturing such a reinforcing element.

[0006] In the tire sector, designers have long been looking for low-density textile or composite reinforcements that can be an advantageous and effective substitute for conventional metal wires or cables, particularly in order to reduce the weight of these tires and also to overcome potential corrosion problems.

[0007] In particular, the top of the tires must be both rigid in tension to transmit forces and avoid deformation of the tire at high speed, but also sufficiently flexible to absorb shocks and resist them.

[0008] The use as reinforcements of composite fabrics comprising both metallic materials and textile materials, in particular aramid, is also known.

[0009] The combination of intrinsically rigid metallic materials and textile materials with intrinsically low bending stiffness results in a composite fabric with reduced bending stiffness.

[0010] However, aramid is a particularly expensive, high-tech textile reinforcement and, given its carbon footprint and its production, which generates high toxicity, its environmental impact is significant.

[0011] The use of composite reinforcements in which fibers are impregnated with a thermosetting matrix is ​​also known. Document ER 3 009 225 describes in particular a single strand of CVR glass resin composite, with the acronym "CVR", in which a glass fiber is impregnated with thermosetting resin.

[0012] Due to the impregnation of the glass fiber by the resin matrix, such composite reinforcements become very rigid in bending and have a high critical bending radius. The critical bending radius is defined as the radius below which a rigid material breaks when it is bent into a loop.

[0013] The present invention therefore aims to overcome the aforementioned drawbacks and to provide a lightweight reinforcing element achieving a compromise of high longitudinal rigidity, high strength, high fatigue resistance, low bending rigidity and low critical radius of curvature.

[0014] The present invention relates to a reinforcing element comprising an assembly of at least two single strands, said single strands each comprising at least one glass fiber and a crosslinked resin coating the glass fiber, said single strands being assembled together by helically winding along an axis of elongation of the reinforcing element.

[0015] It has been determined that the individual impregnation of each single strand with crosslinked resin as well as the assembly of a plurality of single strands by helically winding leads to low bending stiffness and a low critical radius of curvature of the reinforcing element.

[0016] Such a reinforcing element is sufficiently rigid in tension to transmit forces and prevent deformation of an article incorporating the reinforcing element, but also sufficiently flexible to withstand shocks by absorbing the resulting energy.

[0017] In addition, the reinforcing element is inexpensive, low density and has high compressive strength properties.

[0018] Advantageously, the single strands can have an individual twist of less than or equal to 15 turns per meter.

[0019] Preferably, the helix angle P of the assembly is such that 0 < P < 30°, preferably between 3 and 25°. Preferably, the diameter of said single strands is between 0.15 and 1.50 mm, preferably between 0.20 and 1.40 mm, more preferably between 0.25 and 1.20 mm.

[0020] Preferably, the weight ratio of glass fibers in the reinforcing element may be between 50 and 80%, more preferably between 60 and 75%, even more preferably between 65 and 75%.

[0021] Advantageously, the crosslinked resin can be a polyester or vinylester resin.

[0022] Preferably, the crosslinked resin has a Young's modulus measured at 20°C according to standard ISO 6721-5 of at least 2 GPa, preferably at least 4 GPa, which allows the reinforcing element to better withstand compressive stress.

[0023] Preferably, the crosslinked resin has a maximum tan(delta) measured at 20°C according to standard ISO 6721-5 of less than 0.2, preferably less than 0.1, which makes it possible to limit the heat dissipation of the crosslinked resin and therefore of the reinforcing element, and thus to limit the fuel consumption of the tire and the local heating of the structure.

[0024] Preferably, the crosslinked resin comprises acrylate functions.

[0025] More preferably, the crosslinked resin contains acrylate functions.

[0026] Advantageously, the glass fibers may be chosen from: boro-aluminosilicate glass fibers, preferably of type E, aluminosilicate glass fibers, preferably of type E-CR, S or S2, or a mixture thereof.

[0027] The invention also relates to a method of manufacturing a reinforcing element comprising an assembly of at least two single strands.

[0028] By definition, a single strand includes at least one fiber.

[0029] Advantageously, the fiber is chosen from glass fibers, basalt fibers, aramid fibers, fibers derived from biomass, such as flax, hemp, jute, kenaf or ramie and preferably glass fibers. According to one embodiment, the monostrands can be arranged in the form of one or more strands, each strand comprising one or more of said monostrands arranged in a single-layer arrangement.

[0030] For example, the reinforcing element may comprise an assembly of three single strands.

[0031] According to one embodiment, the monostrands may be arranged in the form of one or more strands, each strand comprising one or more of said monostrands arranged in a multi-layer arrangement.

[0032] Advantageously, each strand comprises one or more of said single strands arranged in a multi-layer arrangement comprising an inner layer, an outer layer and optionally one or more intermediate layers arranged between the inner layer and the outer layer.

[0033] For example, the reinforcing element may comprise an inner layer comprising one monostrand and an outer layer comprising six monostrands.

[0034] The invention relates to a method for manufacturing a reinforcing element comprising an assembly of at least two single strands, comprising the following steps: a) providing at least two single strands each comprising at least one fiber; b) coating said single strands by impregnation with a resin; c) at least partially crosslinking the resin; and d) assembling said single strands together by helically winding by cabling along an axis of elongation of the reinforcing element.

[0035] The manufacturing process is particularly simple to implement.

[0036] Advantageously, the single strands can have an individual twist of less than or equal to 15 turns per meter.

[0037] In step b), the monostrands are preferably fully coated with resin, i.e. impregnated with resin over their entire length. Alternatively, the monostrands may be partially coated with resin.

[0038] Advantageously, the fiber can be chosen from glass fibers, basalt fibers, aramid fibers, fibers from biomass, such as linen, hemp, jute, kenaf or ramie.

[0039] Preferably, the fiber is a glass fiber.

[0040] Preferably, the resin at least partially crosslinked in step c) has a Young's modulus measured at 20°C according to standard ISO 6721-5 of at least 2 GPa, preferably at least 4 GPa.

[0041] Preferably, the resin at least partially crosslinked in step c) has a maximum tan(delta) measured at 20°C according to standard ISO 6721-5 of less than 0.2, preferably less than 0.1.

[0042] Preferably, the resin at least partially crosslinked in step c) comprises acrylate functions.

[0043] More preferably, the resin at least partially crosslinked in step c) crosslinked contains acrylate functions.

[0044] The invention also relates to a finished article or semi-finished product comprising a reinforcing element as described above.

[0045] The invention also relates to a tire comprising at least one reinforcing element as described previously.

[0046] According to one characteristic, the tire may comprise a carcass reinforcement anchored in two beads and surmounted radially by a crown reinforcement itself surmounted by a tread, the crown reinforcement being joined to said beads by two sidewalls, the crown reinforcement comprising at least one reinforcing element as described previously.

[0047] The present invention will be better understood and other aims, advantages and characteristics will emerge from the detailed description which follows, comprising embodiments given purely for illustrative purposes and made with reference to the appended drawings, presented as non-limiting examples, which may serve to complete the understanding of the invention and the description of its embodiment and, where appropriate, contribute to its definition, in which: [Fig 1] is a sectional view of a tire according to an embodiment of the invention,

[0048] [Fig 2] is a schematic view of the cross-section of a reinforcing element of the tire of Figure 1 according to one embodiment of the invention,

[0049] [Fig 3] is a front view of the reinforcing element shown in Figure 2,

[0050] [Fig 4] is a schematic view of the cross-section of a reinforcing element according to another embodiment of the invention,

[0051] [Fig 5] illustrates a device for manufacturing a reinforcing element according to one embodiment of the invention, and

[0052] [Fig 6] schematically illustrates the assembly of the single strands of a reinforcing element according to a third embodiment.

[0053] It should be noted that, in the figures, the structural and / or functional elements common to the different embodiments may have the same references. Thus, unless otherwise stated, such elements have identical structural, dimensional and material properties.

[0054] In the description of the invention which is to be made, the expression "at least one" used must be considered as equivalent to the expression "one or more".

[0055] It is also specified that the expression "between" used in the present description of the invention must be understood as including each of the limits mentioned.

[0056] In the figures, a reference X, Y, Z is shown corresponding to the usual axial (X), radial (Y) and circumferential (Z) directions of a tire.

[0057] 1 schematically shows a radial sectional view of a tire according to a first embodiment of the invention and designated by the general reference 10. The tire 10 is substantially of revolution around an axis substantially parallel to the axial direction X. The tire 10 is here intended for a passenger vehicle. The tire 10 has a crown 12 comprising a crown reinforcement 14 comprising a working reinforcement 15 comprising two working plies 16, 18 of working reinforcement elements and a hoop reinforcement 17 comprising a hoop ply 19 of hoop reinforcement elements according to the invention. The crown reinforcement 14 is surmounted by a tread 20 arranged radially outside the crown reinforcement 14. Here, the hoop reinforcement 17, the hoop ply 19, is radially interposed between the working reinforcement 15 and the tread 20.

[0058] The tire also comprises two sidewalls 22 extending the crown 12 radially inwards. The tire 10 further comprises two beads 24 radially inside the sidewalls 22 and each comprising an annular reinforcing structure 26, in this case a bead wire 28, surmounted by a mass of rubber 30 for filling the bead wire, as well as a radial carcass reinforcement 32.

[0059] The carcass reinforcement 32 comprises at least one carcass ply comprising several reinforcing elements, the ply being anchored to each of the beads 24 by a turn-up around the bead wire 28, so as to form in each bead 24 a forward strand 38 extending from the beads through the sidewalls towards the crown 12, and a return strand 40, the radially outer end 42 of the return strand 40 being radially outside the annular reinforcing structure 26. The carcass reinforcement 32 thus extends from the beads 24 through the sidewalls 22 into the crown 12. The carcass reinforcement 32 is arranged radially inside the crown reinforcement 14 and the hoop reinforcement 17. The carcass reinforcement 32 comprises a single carcass ply 34.

[0060] The tire 10 also comprises an internal sealing layer 43, preferably made of butyl, axially inside the sidewalls 22 and radially inside the crown reinforcement 14 and extending between the two beads 24.

[0061] Each working ply 16, 18, hooping ply 19 and carcass ply 34 comprises a polymeric composition in which reinforcing elements of the corresponding ply are embedded. Each polymeric composition, here an elastomeric composition, of the working plies 16, 18, hooping ply 19 and carcass ply 34 is made from a conventional composition for calendering reinforcing elements conventionally comprising a diene elastomer, for example natural rubber, a reinforcing filler, for example carbon black and / or silica, a crosslinking system, for example a vulcanization system, preferably comprising sulfur, stearic acid and zinc oxide, and optionally a vulcanization accelerator and / or retarder and / or various additives.

[0062] We will now describe in more detail the reinforcing elements of the hoop sheet 19.

[0063] Figure 2 is a cross-sectional view of a reinforcing element 50 according to a first embodiment, comprising seven single strands 52 assembled in a “1 + 6” multi-layer arrangement.

[0064] By “single strand” we mean an individual strand.

[0065] As can be seen in Figure 3 and as will be described in more detail later, the single strands 52 of the reinforcing element 50 are assembled together by helically winding along an elongation axis AA of the reinforcing element 50. The elongation axis A-A forms the longitudinal axis of the reinforcing element 50.

[0066] The illustrated reinforcing element 50 comprises a single strand formed by the seven single strands 52.

[0067] By strand is meant an assembly of single strands 52 wound helically with each other around the axis of elongation A - A of the reinforcing element 50.

[0068] The illustrated strand comprises an inner layer CI comprising a single monostrand 52, and an outer layer CE which extends radially around the inner layer CI and which comprises six monostrands 52.

[0069] In the “1+6” arrangement, the single strands 52 of the outer layer CE are helically wound around the unwound single strand 52 of the inner layer CI.

[0070] According to an alternative, the reinforcing element 50 may comprise a plurality of strands, for example a plurality of strands as illustrated in FIGS. 2 and 3, assembled by winding with each other in a helix.

[0071] Each 52 monostrand comprises a glass fiber and a crosslinked resin coating the glass fiber.

[0072] Glass fibers are multifilament, continuous, unidirectional fibers.

[0073] The term “multifilament fiber” means a fiber which comprises several elementary filaments arranged side by side to form a bundle whose elementary fibers are unidirectional while being substantially parallel to each other.

[0074] Such an assembly of a plurality of single strands makes it possible to obtain a reinforcing element 50 of low bending rigidity and low critical radius of curvature, in particular in comparison with a single single strand of diameter identical to the multi-strand assembly of the reinforcing element 50.

[0075] Critical radius of curvature is the radius below which a rigid material breaks when it is bent into a loop.

[0076] The critical radius of curvature is determined by the following protocol: a 30 cm long sample of a reinforcing element 50 is cut. A loop is made by hand and then the loop is introduced around a measuring template. The loop is then tightened and the stress maintained for approximately 1 second so that the sample of the reinforcing element 50 is fully in contact with the measuring template.

[0077] When the sample breaks, particularly by cracking or the appearance of fibrils, the diameter value corresponding to the breakage is noted.

[0078] If the sample does not break, the loop is released, positioned on a smaller diameter and then tightened. This step is carried out until the sample of the reinforcing element 50 breaks.

[0079] The individual coating of each single strand 52 by the crosslinked resin and then the helical winding of the single strands 52 contribute to the conservation of the elongation potential of each glass fiber and therefore to a high overall elongation potential of the reinforcing element 50. The reinforcing element 50 is sufficiently rigid in tension to transmit the forces and prevent deformation of the tire at high speed, but also sufficiently flexible to withstand impacts by absorbing the resulting energy.

[0080] Advantageously, the single strands 52 of the reinforcing element 50 are assembled together by helically winding by cabling.

[0081] By wiring is meant that the single strands 52 are wound relative to each other in a helix. The single strands 52 have a collective twist due to the helix winding but do not have their own individual twist. In other words, the single strands 52 are wound relative to each other in a helix and have a collective twist due solely to this helix winding.

[0082] Preferably, the helix angle P of the assembly is such that 0 < P < 30°, preferably between 3 and 25.

[0083] For example, the helix angle P is equal to 5°.

[0084] Such ranges of values ​​of the helix angle P and the diameter of the single strands are particularly advantageous for reducing the critical radius of curvature and the bending rigidity of the reinforcing element 50.

[0085] Preferably, the single strands 52 each comprising a resin-coated glass fiber, have a diameter of between 0.15 and 1.50 mm, preferably between 0.20 and 1.40 mm, more preferably between 0.25 and 1.20 mm.

[0086] Such diameter value ranges cover both single strands of essentially cylindrical shape, in particular with a circular cross-section, and single strands of different shapes, for example oblong single strands, of more or less flattened shape, or of rectangular cross-section.

[0087] In the case of a non-circular “S” section and unless otherwise specifically indicated, the diameter is by convention the diameter d defined as: d = square root (S / TT).

[0088] The assembly of a plurality of single strands 52 having such a unit diameter makes it possible to obtain a reinforcing element 50 having a critical radius of curvature and a bending rigidity significantly higher than those of a single single strand of diameter similar to that of the assembly of single strands of the reinforcing element 50.

[0089] Preferably, the count of each single strand 52, each comprising a resin-coated glass fiber, is between 45 and 1800 tex, preferably between 50 and 500 tex.

[0090] By titre, we mean the linear mass of each 52 monofilament determined by the following measurement: 6 meters of a sample are cut on a table and then weighed on a precision balance. Three tests are repeated and the average is taken to obtain the linear mass. The titre is expressed in tex and represents the mass in grams of a thousand meters of 52 monofilament, 1 tex being equal to 1 0 6 kg / m.

[0091] Preferably, the weight ratio of glass fibers in the reinforcing element 50 may be between 50 and 80%, more preferably between 60 and 75%, even more preferably between 65 and 75%.

[0092] The crosslinked resin can be a polyester or vinylester resin, more preferably a vinylester resin.

[0093] By "polyester" resin, we mean, in a known manner, a resin of the unsaturated polyester type.

[0094] Glass fibers have high mechanical strength, electrical resistivity, and thermal and chemical inertia properties.

[0095] Advantageously, the glass fibers may be chosen from: boro-aluminosilicate glass fibers, boron-free aluminosilicate glass fibers, or a mixture thereof.

[0096] The boro-aluminosilicate glass fibers may advantageously be E-type boro-aluminosilicate glass fibers.

[0097] Type E boro-aluminosilicate glass fibers include the following:

[0098] SiCh between 52 and 56% by weight;

[0099] CaO between 16 and 25% by weight;

[0100] AI2O3 between 10 and 13% by weight;

[0101] MgO between 0 and 5% by weight; B 2 O3 between 0 and 10% by weight;

[0102] TiCh between 0 and 1.5% by weight;

[0103] Na2O between 0 and 2% by weight;

[0104] K2O between 0 and 2% by weight; and

[0105] Fe2O3 between 0 and 0.08% by weight.

[0106] The percentages of the elements are defined in relation to the total weight of the fiberglass.

[0107] In an alternative embodiment, the glass fibers may be boron-free aluminosilicate glass fibers, such as E-CR type aluminosilicate glass fibers, based on calcium silicate and alumina with a very low content of alkali oxides such as Na2 Û and K2 O, and without boron, having high corrosion resistance properties.

[0108] Aluminosilicate glass fibers of type E-CR include the following elements:

[0109] SiCh between 58 and 63% by weight;

[0110] CaO between 21 and 23% by weight;

[0111] AI2 O3 between 10 and 13% by weight;

[0112] MgO between 2 and 4% by weight;

[0113] TiCh between 1 and 2.5% by weight;

[0114] Na2O between 0 and 1.2% by weight;

[0115] K2O between 0 and 1.2% by weight;

[0116] Fe2O3 between 0 and 0.04% by weight; and

[0117] ZnO between 0 and 3.5% by weight.

[0118] The percentages of the elements are defined in relation to the total weight of the fiberglass.

[0119] In an alternative embodiment, the glass fibers may be aluminosilicate glass fibers, such as S or S2 type glass fibers.

[0120] Glass fibers of type S and S2 have a high silica and alumina content, are boron and alkali free and have particularly high mechanical strength properties.

[0121] Aluminosilicate glass fibers of type S or S 2 comprise the following elements: SiO2: between 60 and 70% by weight;

[0122] AI2O3: between 20 and 30% by weight; and

[0123] MgO: between 5 and 15% by weight;

[0124] The percentages of the elements are defined in relation to the total weight of the fiberglass.

[0125] Advantageously, the glass fibers may comprise a mixture of E, E-CR, S and S2 type glass fibers.

[0126] The reinforcing element 50 is thus a glass resin composite “CVR” presenting high mechanical properties.

[0127] In the illustrated example, the reinforcing elements 50 are integrated into the crown of a tire.

[0128] Alternatively, one or more reinforcing elements 50 may be used for reinforcing another region of a tire or non-pneumatic semi-finished products or finished articles, for example belts, such as timing belts, or in concrete reinforcement applications.

[0129] Figure 4 is a cross-sectional view of a reinforcing element 50' according to a second embodiment, comprising a single strand. The strand comprises three single strands 52 arranged in a single-layer arrangement of 3.

[0130] The portions of the reinforcing element 50' according to the second embodiment similar to the portions of the reinforcing element 50 of the first embodiment are identified with similar reference numbers.

[0131] As can be seen, the reinforcing element 50' comprises three single strands 52 arranged on a single CU layer and wound helically with each other.

[0132] The single strands 52 of the reinforcing element 50, 50' can be arranged in various arrangements.

[0133] In another embodiment, the reinforcing element 50, 50' may comprise an inner layer CI, an outer layer CE and one or more intermediate layers disposed between the inner layer CI and the outer layer CE. For example, the reinforcing element 50, 50' may have an arrangement of the type "1 +6+ 12" and comprise an inner layer CI comprising a single monostrand 52, an intermediate layer comprising six monostrands 6 and an outer layer CE comprising twelve monostrands 52.

[0134] According to another example, the reinforcing element 50, 50' may have an arrangement of the "3+9" type and comprise an inner layer CI comprising three single strands 52 and an outer layer CE comprising nine single strands 52.

[0135] In another embodiment, the reinforcing member 50' may also comprise a plurality of strands helically wound with one another.

[0136] The invention also relates to a method of manufacturing a reinforcing element 50, 50'.

[0137] Figure 5 represents a device 60 for manufacturing a reinforcing element according to the invention.

[0138] In the example illustrated, the manufacturing device 60 is arranged for the manufacturing of a reinforcing element 50” according to a third embodiment of the invention, comprising two single strands.

[0139] The manufacturing device 60 comprises a base 62 on which is mounted a rotation module 64 comprising a rotating nose 66.

[0140] The circumference of the rotary nose 66 comprises a gear toothing 66a meshing with a complementary gear toothing 68a of a transmission member 68. The actuation of a worm screw 70, connected by one of its ends to the transmission member 68 and by its opposite end to a drive element 72, allows the transmission of a torque to the rotary nose 66.

[0141] Two reels 74, each carrying a single strand 52 comprising a glass fiber and a crosslinked resin coating the glass fiber, are arranged upstream of the rotary nose 66, and a reel 86 for storing the reinforcing element 50' is arranged downstream of the rotary nose 66.

[0142] An assembly grid 76 is disposed between the coils 74 of single strands 52, comprising the glass fiber and the crosslinked resin coating the glass fiber, and the rotating nose 66. In addition, a guide grid 78 is disposed between the rotating nose 66 and the assembly grid 76.

[0143] The method for manufacturing the reinforcing element 50” comprises the following steps: a) providing two single strands 52 each comprising at least one fiber; b) coating the two single strands 52 by impregnation with the resin; c) at least partially crosslinking the resin; and d) assembling the two single strands 52 together by helically winding by cabling along the axis of elongation AA of the reinforcing element 50”.

[0144] In step a), the number of single strands 52 is adjusted according to the arrangement of the reinforcing element that one wishes to manufacture.

[0145] Preferably, in step b), the coating of the two single strands 52 with the resin is carried out over the entire surface and over the entire length of each of the fibers.

[0146] In step c), the resin can be crosslinked by any known method, in particular by UV (or UV-visible) radiation, preferably emitting in a spectrum ranging from at least 300 nm to 450 nm.

[0147] Each of the two single strands 52 of fibers impregnated with crosslinked resin are then wound individually onto one of the reels 74.

[0148] In one embodiment, the fiber may be a glass fiber.

[0149] In step b), each of the two single strands 52 is individually coated with the resin.

[0150] Alternatively, the fiber may be chosen from basalt fibers, aramid fiber, fibers from biomass, such as flax, hemp, jute, kenaf or ramie.

[0151] The coils 74 are then arranged on the manufacturing device 60 so as to pass through the assembly grid 76, the guide grid 78 and the rotating nose 66.

[0152] The number and position of the coils 74 can be adjusted depending on the desired arrangement of the reinforcing element. The two single strands 52 converge towards an assembly point 88 located upstream of the rotating nose 66 and downstream of the guide grid 78.

[0153] In step d), the manufacturing device 60 is put into operation.

[0154] As shown in Figure 6, the two single strands 52 from the coils 74 are driven in a forward direction and, simultaneously, the rotating nose 66 rotates and winds the two single strands 52 which pass through it as they advance.

[0155] The two single strands 52 are thus wound in a helix by cabling along the elongation axis AA of the reinforcing element 50”.

[0156] The manufacturing of the 50” reinforcement element can be carried out continuously.

[0157] As the two monostrands 52 advance, rotation of the rotating nose 66 results in a collective twist of the two monostrands 52 which wind to form a helix at the joining point 88.

[0158] The rotation speed of the rotating nose 66 and the forward speed of the two single-strand propellers 52 can be adjusted according to the desired propeller angle and pitch.

[0159] An individual twist along a specific elongation axis of each of the two single strands 52 may result from the winding assembly. This individual twist is negligible or even zero.

[0160] By negligible we mean an individual twist less than or equal to 15 turns per meter.

[0161] As it is manufactured and advanced, the resulting 50” reinforcement element is wound around the 86 reel for storage.

[0162] Examples

[0163] The mechanical resistance properties of four reinforcement elements according to the invention made of CVR composite were studied.

[0164] The glass fibers used are S2 glass fibers, with a tex of 66 and impregnated with vinylester resin. An ER- / 3-5 reinforcing element comprises three S2 glass fibers impregnated with vinylester resin which have been assembled, after crosslinking the resin, by cabling in a 3-by-3 arrangement as illustrated in Figure 4.

[0165] The helix angle of the ER- / 3-5 reinforcement element is equal to 5°.

[0166] Two other reinforcing elements ER-1+6-5 and ER-1 + 6-10 each comprise seven S2 glass fibers impregnated with vinylester resin which were assembled, after crosslinking of the resin, by cabling in a “1+6” arrangement as illustrated in Figure 2.

[0167] The helix angle of the ER-1+6-5 reinforcement element is equal to 5°.

[0168] The helix angle of the ER-1+6-10 reinforcement element is equal to 10°.

[0169] Longitudinal tensile tests were carried out on the ER- / 3-5, ER-1 + 6-5 and ER-1+6-10 reinforcing elements. A comparative test was also carried out on a control ER-T reinforcing element comprising a single monofilament comprising a glass fibre and a crosslinked resin coating the glass fibre similar to the glass fibres used for the manufacture of the ER- / 3-5, ER-1+6-5 and ER-1+6-10 reinforcing elements.

[0170] Longitudinal tensile tests were performed according to ISO 2062 using an Instron 5969 device equipped with an IkN load cell, using wire tensile clamps with a pretension of 0.5 cN / tex, a gauge length of 400 mm and a strain rate of 200 mm / min.

[0171] For each tensile test, a stress-strain curve was obtained and the results are shown in Table 1 below.

[0172] Table 1: In Table 1, a is the strain or “elongation” in % and Fr is the breaking force in N.

[0173] It can be seen that the yield and elongation values ​​of the ER- / 3-5, ER- 1 + 6-5 and ER- 1 + 6- 10 reinforcing elements are maintained while having a much higher breaking strength than that of the single-strand control ER-T reinforcing element.

[0174] The yield is defined as the ratio between, on the one hand, the breaking strength of the assembled reinforcing element and, on the other hand, the sum of the breaking strength of the single strands making up the assembled reinforcing element.

Claims

CLAIMS 1. Reinforcing element (50; 50'; 50") comprising an assembly of at least two single strands (52), said single strands (52) each comprising at least one glass fiber and a crosslinked resin coating the glass fiber, said single strands (52) being assembled together by helically winding along an elongation axis (AA) of the reinforcing element (50; 50'; 50").

2. Reinforcing element according to claim 1, in which the helix angle P of the assembly is such that 0° < P < 30°, preferably between 3° and 25°.

3. Reinforcing element according to claim 1 or 2, in which the diameter of said single strands (52) is between 0.15 and 1.50 mm, preferably between 0.20 and 1.40 mm, more preferably between 0.25 and 1.20 mm.

4. Reinforcing element according to any one of the preceding claims, in which the weight ratio of glass fibers in the reinforcing element (50; 50'; 50") is between 50 and 80%, preferably between 60 and 75%, even more preferably between 65 and 75%.

5. Reinforcing element according to any one of the preceding claims, in which the crosslinked resin is a polyester or vinylester resin.

6. Reinforcing element according to any one of the preceding claims, wherein said glass fibers are chosen from: boro-aluminosilicate glass fibers, preferably of type E, aluminosilicate glass fibers, preferably of type E-CR, S or S2, or a mixture thereof.

7. Reinforcing element according to any one of the preceding claims, in which the crosslinked resin has a Young's modulus measured at 20°C according to standard ISO 6721-5 of at least 2 GPa, preferably at least 4 GPa.

8. Reinforcing element according to any one of the preceding claims, in which the crosslinked resin has a maximum tan(delta) measured at 20°C according to standard ISO 6721-5 of less than 0.2, preferably less than 0.

1.

9. Reinforcing element according to any one of the preceding claims, in which the crosslinked resin contains acrylate functions.

10. A reinforcing element according to any one of the preceding claims, wherein said monostrands (52) are arranged in the form of one or more strands, each strand comprising one or more of said monostrands (52) arranged in a single-layer arrangement, preferably comprising three monostrands (52). 1 1. Reinforcing element according to any one of claims 1 to 9, wherein said monostrands (52) are arranged in the form of one or more strands, each strand comprising one or more of said monostrands (52) arranged in a multi-layer arrangement comprising an inner layer (CI), an outer layer (CE) and optionally one or more intermediate layers arranged between the inner layer (CI) and the outer layer (CE), preferably comprising an inner layer (CI) comprising one monostrand (52) and an outer layer (CE) comprising six monostrands (52).

12. Method for manufacturing a reinforcing element (50; 50'; 50") comprising an assembly of at least two single strands (52) comprising the following steps: a) providing at least two single strands (52) each comprising at least one fiber; b) coating said single strands (52) by impregnation with a resin; c) at least partially crosslinking the resin; and d) assembling said single strands (52) together by helically winding by cabling along an elongation axis (AA) of the reinforcing element (50; 50'; 50").

13. Method according to claim 12, in which the fiber is chosen from glass fibers, basalt fibers, aramid fibers, biomass fibers, such as flax, hemp, jute, kenaf or ramie and preferably glass fibers.

14. Finished article or semi-finished product comprising a reinforcing element (50; 50'; 50") according to any one of claims 1 to 11.

15. Tire comprising at least one reinforcing element (50; 50'; 50") according to any one of claims 1 to 11.

16. A tire according to claim 15, comprising a carcass reinforcement (24) anchored in two beads (18) and surmounted radially by a crown reinforcement (14) itself surmounted by a tread (22), the crown reinforcement (14) being joined to said beads (18) by two sidewalls (16), the crown reinforcement (14) comprising at least one reinforcing element (50; 50'; 50") according to any one of claims 1 to 11.

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