Elastomer composite with a plurality of reinforcing elements sewn in a main direction

Abstract

The invention relates to an elastomer composite (35) having a thickness E measured in a direction (Y) which is perpendicular to the main direction (X), comprising a plurality of thread-like reinforcing elements (45) which are substantially parallel to one another, and an elastomer composition having a secant modulus of elasticity MA10 at 10% deformation, determined according to the NF ISO 37 standard of February 2018, ranging from 2.5 to 55.0 MPa, wherein each reinforcing element (45) is sewn through the thickness of the elastomer composition.

Description

[0001] Elastomer composite with a plurality of reinforcing elements sewn in a main direction

[0002]

[0001] The present invention relates to a tire composite comprising a plurality of stitched reinforcing elements.

[0003]

[0002] Known from the state of the art, in particular from application EP 3988347, is a tire comprising a carcass ply which comprises a sewn portion into which a conductive thread is sewn to allow the static electricity of a vehicle to be easily released to the ground.

[0004]

[0003] Also known from the state of the art, in particular from application EP 1279481, is a method for orienting short fibers in a composite in two directions and in particular the direction of the thickness of the composite and in particular after calendering which imposes a single direction of orientation of the fibers.

[0005]

[0004] Such a process makes it possible to orient the fibers in the thickness of the composite after their calendering but it does not make it possible to control the properties of the composite and in particular the reinforcement of the composite.

[0006]

[0005] Document EP3403854 is also known from the state of the art.

[0007]

[0006] The aim of the invention is to find a composite which is free from the constraints linked to calendering while making it possible to control its properties and in particular its breaking strength and also to save on the cutting of these composites.

[0008]

[0007] For this purpose, the subject of the invention is an elastomer composite having a thickness E measured in a direction (Y) perpendicular to the main direction (X), comprising a plurality of wire reinforcement elements substantially parallel to each other and an elastomer composition having a secant elastic modulus MA10 at 10% deformation determined according to standard NF ISO 37 of February 2018 ranging from 2.5 to 55.0 MPa in which each reinforcement element is sewn continuously through the thickness of the elastomer composition.

[0009]

[0008] By substantially parallel is meant that the distance between two consecutive reinforcing elements is substantially constant.

[0010]

[0009] By elastomer composition is meant a composition comprising an elastomer, preferably diene, for example natural rubber, a reinforcing filler, for example carbon black and / or silica and a crosslinking system, for example a vulcanization system, preferably comprising sulfur.

[0011]

[0010] Preferably, the elastomer composition comprises a diene elastomer.

[0011] In one embodiment, the elastomer composition is uncured, for example unvulcanized.

[0012]

[0012] In another embodiment, the elastomer composition is cured, preferably under pressure, for example vulcanized.

[0013]

[0013] By definition, the MA10 is the secant elastic modulus in tension of a vulcanized polymer matrix measured at 10% elongation from a stress-elongation curve produced according to the recommendations of the NF ISO 37 standard of February 2018. This is the elastic modulus of the mixture measured during a uniaxial tensile experiment, at an elongation value of 0.1 (i.e. 10% elongation, expressed as a percentage). A constant uniaxial tensile speed is imposed on the test piece, and its elongation and force are measured. The measurement is carried out using an INSTRON type tensile machine, at a temperature of 23°C, and a relative humidity of 50% (ISO 23529 standard). The conditions for measuring and using the results to determine the elongation and stress are as described in standard NF ISO 37: 2018-02. The stress is determined for an elongation of 0.1 and the elastic modulus at 10% is calculated by calculating the ratio of this stress value to the elongation value. A person skilled in the art will know how to choose and adapt the dimensions of the test piece according to the quantity of accessible and available mixture, particularly in the case of taking samples from a finished product such as a tire.

[0014]

[0014] This continuous alignment of the reinforcing elements in the thickness of the composite thus makes it possible to select the properties of elongation at break and strength at break of the composite.

[0015]

[0015] By continuously sewn through the thickness of the elastomer composition, it is meant that if a section is made in the plane (X; Y), the reinforcing element is present along the entire thickness E measured in a direction (Y).

[0016]

[0016] Preferably, in a first embodiment, the tire composite comprises a plurality of reinforcing elements which extend in the main direction (X).

[0017]

[0017] In a second embodiment, the tire composite comprises a plurality of reinforcing elements which extend in the direction (Z) perpendicular to the main direction (X).

[0018] In this first embodiment, the density of reinforcing elements in the composite ranges from 15 to 150 reinforcing elements per decimeter of composite, preferably from 15 to 130 reinforcing elements per decimeter of composite.

[0018]

[0019] The density of reinforcing elements in the composite is the number of reinforcing elements taken on one decimeter of the composite in the direction perpendicular to the direction in which the reinforcing elements extend parallel to each other. In this range of reinforcing element density, the composite has a relatively high breaking strength compared to a composite without reinforcing elements in the transverse direction perpendicular to the main direction of the reinforcing elements.

[0019]

[0020] Advantageously, each reinforcing element is a textile reinforcing element.

[0021] Preferably, the reinforcing elements are sewn with a stitch.

[0020]

[0022] A backstitch is a row of forward stitches combined with backstitching to make a continuous line on the right and wrong sides of the composite.

[0021]

[0023] Advantageously, each textile reinforcement element comprises a layer of an adhesive composition.

[0022]

[0024] We will mention the adhesive compositions of the RFL type (Resorcinol - Formaldehyde - Latex) but also the adhesive compositions as described in WO201 5118041.

[0023]

[0025] Preferably, each reinforcing element may also be impregnated with a pre-adhesive of aqueous composition, in particular for fibers and / or filaments having a poor affinity with RFL type adhesive compositions. This pre-adhesive step is carried out upstream of the step of manufacturing the textile reinforcing element. Examples include pre-adhesives containing epoxy compounds and isocyanate compounds.

[0024]

[0026] The amount of adhesive composition is measured by chemical attack, either by attack of the adhesive composition or by attack of the fiber.

[0025]

[0027] For polyamides, chemical attack is carried out by attacking the fiber with a hot acid solution. The fiber is thus destroyed and the residue consisting of the adhesive composition is recovered and weighed. The weight of the adhesive composition is determined by relating the weight of the residue to the weight of the dry, unsized fiber.

[0026]

[0028] For other fibers such as polyester, polyurethane polyketone, acrylic, polyolefin or polyetheretherketone fibers, chemical attack is carried out by attacking the adhesive composition with an acidic oxidizing solution. The adhesive composition as well as the size and pre-adhesive are destroyed.

[0027]

[0029] The residue consisting of the fibers is recovered and weighed. The determination of the weight of the adhesive composition is obtained by weighing the fibers before and after attack of the adhesive composition, correcting the result obtained by the quantity of sizing and pre-adhesive deposited on the fiber.

[0028]

[0030] The quantity of sizing and pre-adhesive deposited on the fiber can be determined experimentally by attacking the unbleached fiber.

[0029]

[0031] Preferably, in one embodiment, the textile reinforcing element comprises a single multifilament strand.

[0030]

[0032] A strand is a unitary element of very great length and continuous generally obtained by spinning a molten material. It can be either artificial or synthetic.

[0031]

[0033] Preferably, in this embodiment, the textile reinforcing element consists of a single multifilament strand.

[0032]

[0034] In another embodiment, the textile reinforcing element comprises an assembly consisting of two multifilament strands, the two strands being helically wound around each other and preferably, the reinforcing element is twist balanced.

[0033]

[0035] Preferably, the multifilament strand(s) are chosen from polyester strands, polyamide strands, polyketone strands, polyurethane strands, acrylic strands, polyolefin strands, polyetheretherketone strands and assemblies of these filaments and these fibers, preferably from polyester strands, polyamide strands and assemblies of these filaments and these fibers and more preferably the organic synthetic strands are polyester or polyamide filaments and fibers such as nylons PA4.6, PA56, PA6, PA6.6 and also PA6.10.

[0034]

[0036] Advantageously, the multifilament strands are chosen from polyester strands, aliphatic polyamide strands, strands comprising aromatic polyamides or aromatic copolyamides and strands comprising mixtures of filaments of these materials, preferably chosen from aliphatic polyamide strands and more preferably made of nylon 6.6.

[0035]

[0037] By definition, a textile reinforcement element is an assembly of these strands. Each reinforcement element is impregnated with a composition ensuring the cohesion of these strands with each other and preventing the fraying of each reinforcement element.

[0036]

[0038] Polyester strands are a set of filaments made up of linear macromolecules formed by groups linked together by ester bonds. Polyesters are manufactured by polycondensation, by esterification between a dicarboxylic acid or one of its derivatives, a diol. For example, polyethylene terephthalate can be manufactured by polycondensation of terephthalic acid and ethylene glycol. Among the known polyesters, we can cite polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), polybutylene naphthalate (PBN), polypropylene terephthalate (PPT) or polypropylene naphthalate (PPN).

[0037]

[0039] By aromatic polyamide strand or aromatic copolyamide, it is well known that it is a set of filaments made up of linear macromolecules formed of aromatic groups linked together by amide bonds of which at least 85% are directly linked to two aromatic nuclei, and more particularly of poly (p-phenylene terephthalamide) (or PPTA) fibers, manufactured for a very long time from optically anisotropic spinning compositions.Among the aromatic polyamides or aromatic copolyamides, mention may be made of polyarylamides (or PAA, known in particular under the trade name “Ixef” from the company Solvay), poly(metaxylylene adipamide), polyphthalamides (or PPA, known in particular under the trade name “Amodel” from the company Solvay), amorphous semi-aromatic polyamides (or PA 6-3T, known in particular under the trade name “Trogamid” from the company Evonik), meta-aramids (or poly(metaphenylene isophthalamide or PA MPD-I known in particular under the trade name “Nomex” from the company Du Pont de Nemours) or para-aramids (or poly(paraphenylene terephthalamide or PA PPD-T known in particular under the trade name “Kevlar” from the company Du Pont de Nemours or “Twaron” from the company Teijin).

[0038]

[0040] Aliphatic polyamide strands are defined as a set of filaments made up of linear macromolecules of polymers or copolymers containing amide functions that do not have aromatic cycles and can be synthesized by polycondensation between a carboxylic acid and an amine. Aliphatic polyamides include nylons PA4.6, PA6, PA6.6 or PA6.10, and in particular "Zytel" from DuPont, "Technyl" from Solvay or "Rilsamid" from Arkema.

[0039]

[0041] Advantageously, the title of the aliphatic polyamide strand ranges from 7 to 660 tex, preferably from 50 to 440 tex, more preferably from 90 to 220 tex.

[0040]

[0042] Preferably, the titer of the aliphatic polyamide strand ranges from 70 to 120 tex and preferably from 90 to 110 tex.

[0041]

[0043] The density (or linear mass) of each strand is determined according to ASTM D1423. The density is given in tex (mass in grams of 1000 m of product - reminder: 0.111 tex equals 1 denier). The density of reinforcing elements in the composite is the number of reinforcing elements taken on one decimeter of the composite in the direction perpendicular to the direction in which the reinforcing elements extend parallel to each other.

[0042]

[0044] Preferably, the diameter of the reinforcing element is less than or equal to 0.95 mm, preferably less than or equal to 0.80 mm, more preferably less than or equal to 0.70 mm.

[0043]

[0045] Advantageously, the torsion of the reinforcing element ranges from 200 to 500 turns per meter and preferably from 250 to 490 turns per meter.

[0044]

[0046] Advantageously, the thickness E of the composite is less than or equal to 6.0 mm, preferably less than or equal to 5.0 mm and more preferably less than or equal to 4.5 mm.

[0045]

[0047] Advantageously, the thickness E of the composite is greater than or equal to 1.0 mm and preferably greater than or equal to 2.0 mm.

[0046]

[0048] The thickness of the composite is the shortest distance between the two external surfaces of the composite, that is, the distance measured in a direction perpendicular to the two external surfaces of the composite.

[0047]

[0049] Another subject of the invention is a tire comprising at least one elastomer composite as described previously.

[0048]

[0050] Preferably, the tires may be intended for motor vehicles of the passenger car, 4x4, "SUV" (Sport Utility Vehicles) type.

[0049]

[0051] The invention will be better understood in light of the following description, given solely by way of non-limiting example and with reference to the drawings in which:

[0050] - figure 1 illustrates a composite (35) according to the invention;

[0051] - Figure 2 is a photograph of the composites (30; 35; 35') according to the invention; and - Figure 3 illustrates the stress-elongation curve for the composites (30; 35; 35') according to the invention and the composite of the state of the art.

[0052] EXAMPLE OF A COMPOSITE ACCORDING TO THE INVENTION

[0053]

[0052] The composite 35 comprises reinforcing elements 45 sewn into an elastomer composition in which each reinforcing element 45 is sewn continuously through the thickness of the elastomer composition. The reinforcing elements 45 are substantially parallel to each other and extend in a main direction (X).

[0054]

[0053] The reinforcing elements extend continuously in a main direction (X) and are textile reinforcing elements.

[0055]

[0054] The reinforcing elements are sewn by stitching.

[0056] Nature of the strands of each reinforcing element

[0057]

[0055] The textile reinforcing element (45) comprises a single multifilament strand, made of aliphatic polyamide and more precisely of nylon 6,6.

[0058] Title of each reinforcement element

[0059]

[0056] The count of the multifilament strand of aliphatic polyamide of the warp reinforcing element ranges from 70 to 120 tex and preferably from 90 to 110 tex. Here the count of each multifilament strand of aliphatic polyamide 6,6 of the reinforcing element is 105 tex.

[0060]

[0057] The reinforcing element also comprises a layer of an adhesive composition coating it. Such an adhesive composition is for example of the RFL type (acronym for Resorcinol-Formaldehyde-Latex) but also the adhesive compositions as described in WO201511804. Here, the nylon 6,6 is previously glued with an RFL composition.

[0061]

[0058] The diameter of the reinforcing element is less than or equal to 0.95 mm, preferably less than or equal to 0.80 mm, more preferably less than or equal to 0.70 mm. Here, the diameter of the reinforcing element is 0.38 mm.

[0062] Torsion of each reinforcement element

[0063]

[0059] The twist of the reinforcing element ranges from 200 to 500 turns per meter and preferably from 250 to 490 turns per meter. Here, the twist of the reinforcing element is 345 turns per meter.

[0064] Density of reinforcing elements in the composite

[0065]

[0060] The density of the reinforcing elements in the composite of 15 to 150 reinforcing elements per decimeter of composite measured in a transverse direction (Y) perpendicular to the main direction of the reinforcing elements, preferably ranges from 15 to 130 reinforcing elements per decimeter of composite and more preferably it ranges from 15 to 125 reinforcing elements per decimeter of composite. Here, it is 20 threads per dm of composite.

[0066] Geometric characteristics of the composite

[0067]

[0061] The thickness of the composite is less than or equal to 6.0 mm, preferably less than or equal to 5.0 mm, more preferably less than or equal to 4.5 mm. The thickness E of the composite is greater than or equal to 1.0 mm and preferably greater than or equal to 2.0 mm, here it is 2.5 mm.

[0068]

[0062] The elastomer composition has a secant elastic modulus MA10 at 10% deformation determined according to the NF ISO 37 standard of February 2018 ranging from 2.5 to 55.0 MPa. Here for the composite, the secant elastic modulus MA10 at 10% elongation is 55 MPa.

[0069] METHOD FOR MANUFACTURING THE COMPOSITE ACCORDING TO THE INVENTION

[0070]

[0063] Each composite 35 is manufactured by sewing the reinforcing element 45 to the elastomer composition via the sewing machine by selecting the stitching point. The elastomer composition conventionally comprises 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. The elastomer composition is uncured.

[0071] MEASUREMENTS AND COMPARATIVE TESTS

[0072]

[0064] Table 1 summarizes the characteristics of the TEDT composites of the state of the art without sewn reinforcing elements, the composite 30 according to the invention with a seam along the (Z) axis, and the composites 35 and 35' according to the invention with a seam along the (Y) axis.

[0073]

[0065] Tensile tests

[0074] Production of test specimens:

[0075]

[0066] A strip of mixture with a minimum dimension of 15 mm by 150 mm is left raw depending on the test to be carried out. The test piece is then cut using a die cutter. The tensile strength of the test pieces is achieved using an INSTRON tensile testing machine at a speed of 100 mm / min.

[0067] The force-elongation curves of the TEDT composites of the state of the art, and of the composites 30, 35 and 35' according to the invention were plotted by applying the ASTM D 2969-04 of 2014 standard as shown in Figure 3 and the improvement in reinforcement in the 20 to 25% elongation range compared to the composite of the state of the art TEDT was determined.

[0076]

[0068] [Table 1]

[0077]

[0069] It is noted that the stitching, whatever its direction, reduces the elongations at break of the composites 30, 35 and 35' as shown in Figure 3 and in Table 1 compared to the TEDT composite.

[0070] It is noted that the stitching in the width direction reinforces the composite 30 compared to the TEDT composite.

[0071] It is also noted that the stitching in the length direction reinforces the composite 35, 35' even more compared to the composite 30 and compared to the TEDT composite.

[0078]

[0072] The higher the density, the greater the reinforcement if we compare composite 35 to composite 35'.

[0079]

[0073] Thus, the composites according to the invention make it possible to overcome the constraints linked to calendering while making it possible to control the properties of the composite and in particular its breaking strength and also to save on the cutting of these composites.

[0080]

[0074] The invention is not limited to the embodiments previously described.

[0081]

[0075] It is also possible to combine the characteristics of the different embodiments and variants described or envisaged above, provided that they are compatible with each other.

Claims

CLAIMS 1. Elastomer composite (35) for a tire having a thickness E measured in a direction (Y) perpendicular to the main direction (X), characterized in that it comprises a plurality of wire reinforcement elements (45) substantially parallel to each other and an elastomer composition having a secant elastic modulus MA10 at 10% deformation determined according to standard NF ISO 37 of February 2018 ranging from 2.5 to 55.0 MPa in which each reinforcement element (45) is sewn continuously through the thickness of the elastomer composition; in which each reinforcement element (45) extends in the main direction (X) and in which the density of reinforcement elements (45) in the composite (35) ranges from 15 to 150 reinforcement elements per decimeter of composite.

2. Elastomer composite (35) according to the preceding claim, wherein the density of reinforcing elements (45) in the composite (35) ranges from 15 to 130 reinforcing elements per decimeter of composite.

3. An elastomer composite (35) according to any preceding claim, wherein each reinforcing element (45) is a textile reinforcing element.

4. Elastomer composite (35) according to any one of the preceding claims, in which the reinforcing elements are stitched.

5. Elastomer composite (35) according to the preceding claim, wherein each textile reinforcing element (45) comprises a layer of an adhesive composition.

6. Elastomer composite (35) according to any one of claims 2 to 5, wherein the textile reinforcing element (45) comprises a single multifilament strand.

7. Elastomer composite (35) according to any one of claims 2 to 5, wherein the textile reinforcing element (45) comprises an assembly consisting of two multifilament strands, the two strands being wound helically around each other and preferably, the reinforcing element is torsionally balanced.

8. Elastomer composite (35) according to claim 6 or 7, in which the multifilament strand(s) are chosen from polyester strands, aliphatic polyamide strands, strands comprising aromatic polyamides or aromatic copolyamides and strands comprising mixtures of filaments of these materials, preferably chosen from aliphatic polyamide strands and more preferably made of nylon 6.

6.

9. Elastomer composite (35) according to the preceding claim, in which the count of the aliphatic polyamide strand ranges from 70 to 120 tex and preferably from 90 to 110 tex.

10. Elastomer composite (35) according to any one of the preceding claims, wherein the thickness E of the composite (35) is less than or equal to 6.0 mm, preferably less than or equal to 5.0 mm and more preferably less than or equal to 4.5 mm.

11. Tire, characterized in that it comprises at least one elastomer composite (35) according to any one of claims 1 to 10.

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