POLYETHYLENE FURANOATE THREAD AND ITS MANUFACTURING PROCESS

Abstract

The invention relates to a yarn comprising polyethylene-2,5-furanedicarboxylate (PEF) filaments having a tenacity at break of at least 4 cN / dTex and an energy at break, defined as the product of the tenacity at break in cN / dTex by the elongation at break in %, of at least 40 cN / dTex, the tenacity at break and the elongation at break being determined according to ASTM D885-03 and its preparation process.

Description

Title of the invention: POLYETHYLENE FURANOATE YARN AND METHOD FOR PRODUCING THE SAME Technical field of the invention

[0001] The present invention relates to the field of textile yarns and their preparation process. Prior art

[0002] Polyesters have numerous applications in the industrial and textile fields. Their versatility is such that the volumes produced each year are very large. Therefore, it is of interest to synthesize polyesters from monomers derived from renewable resources, and having technical characteristics allowing them to be substituted for petroleum-based polyesters, such as, for example, polyethylene terephthalate (PET).

[0003] Much research has been carried out to produce polyesters from furanedicarboxylate monomers. These can in fact be obtained from renewable resources such as sugars, which makes it possible to envisage a reduction in the environmental impact of the production of these polyesters. The synthesis of polyester typically comprises an esterification step and a polycondensation step, possibly followed by crystallization and post-condensation steps in the solid state in order to adjust the properties of the polyester, then a shaping step, in particular spinning when the aim is to obtain a yarn. The structure, and therefore the characteristics, of the polyester obtained depends on the conduct of these different steps.

[0004] Among the various properties sought, and in particular for uses in rubber articles such as tires or conveyor belts, it is desired that the threads be able to withstand high thermo-mechanical stresses and therefore have both high mechanical tensile strength and elongation at break, high tensile rigidity and high thermal resistance.

[0005] Document EP 3 348 679 describes, for example, that the combination of a drawing ratio greater than 6 associated with a ratio of the winding speed of the yarn to the speed at the outlet of the filament extrusion die ("spin draft" according to English terminology) ranging from 700 to 2000 makes it possible to obtain a PEF yarn having a high storage modulus (the storage modulus being defined in a known manner as the real part of the dynamic modulus, or complex modulus, which represents the response of the material to dynamic stress) and a relatively high tenacity, greater than 3.0 cN / dTex.

[0006] Document WO2014 / 204313 teaches the manufacture of PEF yarns having relatively high tenacities, at the cost of elongation at break. These yarns are obtained by spinning PEF in a first stage conducted at 90°C at a draw ratio of 2.5 followed by a second stage conducted at a temperature of 100°C or 150°C at a draw ratio of 1.8 (i.e. a total draw ratio of 4.5).

[0007] However, it remains desirable to obtain yarns having both high tenacity at break, while maintaining a high elongation at break, which is expressed by the energy at break, defined as the product of the tenacity at break in cN / dTex by the elongation at break in %, expressed in cN / dTex and homogeneous at [J] / [kg]. Detailed description of the invention

[0008] The invention relates to a yarn comprising polyethylene-2,5-furanedicarboxylate (PEF) filaments having a tenacity at break of at least 4 cN / dTex and a breaking energy, defined as the product of the tenacity at break in cN / dTex and the elongation at break in %, of at least 40 cN / dTex, the tenacity at break and the elongation at break being determined according to ASTM D885-03. Definitions

[0009] The carbon-containing compounds mentioned in the description may be of fossil or bio-sourced origin. In the latter case, they may be, partially or totally, derived from biomass or obtained from renewable raw materials derived from biomass. This concerns in particular polymers, plasticizers, fillers, etc. Yarn according to the invention

[0010] The invention relates to a yarn comprising polyethylene-2,5-furanedicarboxylate (PEF) filaments having a tenacity at break at least equal to 4 cN / dTex and a breaking energy, defined as the product of the tenacity at break in cN / dTex by the elongation at break in %, at least equal to 40 cN / dTex, the tenacity at break and the elongation at break being determined according to ASTM D885-03.

[0011] PEF is a polyester comprising ethylene 2,5-furanedicarboxylate units and diethylene glycol units.

[0012] The yarn according to the invention preferably has a secant modulus at 3 cN / dTex at least equal to 13 GPa, preferably at least equal to 15 GPa. Such a secant modulus allows the yarn according to the invention to have very good tensile rigidity, useful for its use as a reinforcing element for rubber articles such as pneumatic or non-pneumatic tires, or conveyor belts.

[0013] Preferably, the yarn according to the invention has an elongation at break greater than 6%, preferably at least equal to 8%. Such an elongation at break, associated with the other characteristics of the yarn, allows it to withstand strong stresses. mechanical stresses that may be experienced by rubber articles such as pneumatic or non-pneumatic tires, or conveyor belts.

[0014] Preferably, the PEF constituting the filaments of the yarn according to the invention has a melting temperature at least equal to 215°C. Such a melting temperature allows the yarn according to the invention to respond to high thermal stresses, for example during the curing of rubber articles in which the yarn can be used as a reinforcing element.

[0015] Preferably, the yarn according to the invention is made up of PEF filaments. By made up of, it is meant that the yarn according to the invention preferably does not comprise filaments of a chemical nature other than PEF filaments, and in particular does not comprise PET (polyethylene terephthalate) filaments. Indeed, the thermomechanical properties of the yarn according to the invention are sufficient for it to be used without requiring reinforcement of the yarn with filaments of another chemical nature.

[0016] The invention also relates to a textile article comprising at least one yarn according to the invention, or a yarn prepared according to the method described below. This article may be a reinforcing element such as those used in vehicle tires, or a fabric, usable for making clothing, inflatable articles or the like.

[0017] To make the textile article, the yarn according to the invention, or the yarn prepared according to the process according to the invention, can undergo twisting, overtwisting, wrapping, weaving, knitting, braiding, 2D or 3D actions with only yarns according to the invention or in combination with another yarn known to those skilled in the art such as a yarn of polyester, polyamide, aramid, natural fibers or regenerated fibers.

[0018] The invention also relates to a reinforced product comprising a yarn according to the invention or a yarn prepared according to the process according to the invention embedded in a polymer matrix, in particular embedded in an elastomeric matrix.

[0019] Such a reinforced product may be any product reinforced by a textile article, in particular a reinforced product chosen from transmission belts, conveyor belts, inflatable articles and vehicle wheel tires.

[0020] Synthesis of the PEF used in the yarn according to the invention

[0021] The PEF used in the yarn according to the invention is synthesized by a process implementing at least the following steps: • An esterification step; • A polycondensation step; • A crystallization step; • A solid-state post-condensation step; • A shaping step in the form of granules. Esterification step

[0022] The process for synthesizing PEF implemented in the yarn according to the invention comprises a step of esterification of a composition comprising a dimethyl-2,5-furanedicarboxylate compound, denoted DMF, said composition also comprising ethylene glycol, denoted EG, this esterification step being carried out at a temperature increasing in the range from 150°C to at least 185°C with an EG / DMF molar ratio ranging from 3 to 1.3 in the presence of a Lewis acid catalyst.

[0023] The esterification step makes it possible to produce ethylene-furanedicarboxylate oligomers from the reaction of ethylene glycol with the furanedicarboxylate compound. The operating conditions of this step have a decisive influence on the structure of the polyester obtained. In the composition feeding this step, the EG / DMF molar ratio is preferably between 2 and 1.5. Below 1.3, the rate of progress of the reaction is significantly impacted, while above 3, the content of diethylene glycol (DEG) unit in the polyester becomes too high.

[0024] The esterification step is carried out for a period preferably ranging from 1 to 5 hours, more preferably ranging from 2 to 4 hours.

[0025] According to the invention, the esterification step is carried out at a temperature increasing in the range from 150°C to at least 185°C. By "increasing in the range from 150°C to at least 185°C", it is meant that the esterification step is carried out at a temperature included in the temperature range from 150°C to at least 185°C, the operating temperature increasing during the esterification step. The implementation of an increasing temperature profile makes it possible to obtain a polyester which has, in particular, a very high melting temperature, in particular, in association with the other operating parameters, by obtaining a very low DEG unit content and by a very low quantity of ester functions located at the end of the chain.

[0026] In a preferred arrangement, the temperature increases continuously in the range from 150°C to at least 185°C according to a ramp less than or equal to +1°C / min, preferably less than or equal to +0.5°C / min. When the highest temperature is reached, a plateau can be maintained until the esterification rate is greater than 80%.

[0027] In another preferred arrangement, the temperature increases in the range from 150°C to at least 185°C in steps within a range from 5 to 15°C. Preferably, each step lasts independently from 15 min to 2h30. Very preferably, the esterification step is carried out with at least three temperature steps.

[0028] The highest temperature at which the esterification step is carried out is preferably in the range from 185°C to 205°C, preferably from 185°C to 200°C, and very preferably ranging from 190°C to 200°C. Below 185°C, the rate of progress of the reaction is significantly impacted, resulting in insufficient conversion of the ester chain ends and final intrinsic viscosity, while above 205°C, the DEG unit content in the polyester increases significantly.

[0029] Preferably, the duration between the end of the first stage and the start of the last stage, or between the lowest and highest temperature of the esterification step when the temperature increases continuously, is at least equal to 30 min, preferably at least equal to 45 min. Indeed, it has been observed that when the temperature increase was too rapid, higher DEG unit contents were obtained.

[0030] It has been observed by the applicant that the application of these particular temperature conditions made it possible, the other operating conditions of the invention being respected, to greatly limit the formation of DEG units in the polyester while ensuring good reaction kinetics.

[0031] For example, the esterification step can be carried out for 1 h at 160°C, then 1 h at 170°C and finally 2 h at 195°C. In this case, the stages are respectively 10°C and 25°C and the respective duration of each of the three stages is 1 h, 1 h and 2 h.

[0032] The esterification step is preferably carried out at moderate pressure, ranging from 0.8 to 2 bar. Preferably, the step is carried out under an inert atmosphere. The operation at moderate pressure, or even at slight overpressure or underpressure, i.e. preferably between 800 and 1700 mbar, makes it possible to carry out the esterification step in the liquid phase while removing reaction products such as water.

[0033] The esterification step is carried out in the presence of a Lewis acid catalyst. Preferably, the Lewis acid catalyst is chosen from hafnium acetylacetonate, zirconium acetylacetonate, titanium isopropoxide (TIS) and titanium tetrabutoxide (TBT). Preferably, the Lewis acid catalyst is titanium tetrabutoxide (TBT), the latter making it possible to obtain a low level of DEG units as well as a low level of decarboxylation at the end of the chain.

[0034] The esterification step is carried out with a catalyst content ranging from 100 to 1000 ppm, preferably ranging from 150 to 500 ppm, and very preferably ranging from 200 to 450 ppm.

[0035] These operating conditions, with a temperature increasing in stages in the mentioned range and in the presence of a Lewis acid catalyst, in particular a catalyst such as titanium tetrabutoxide (TBT), make it possible to greatly limit the formation of DEG units in the polymer, while guaranteeing an esterification rate greater than 80%, a quantity of ester functions located at the end of chain less than 100 meq / kg, preferably less than 80 meq / kg at the end of esterification for the polyester prepolymer obtained. The esterification rate is determined by dividing the mass of water resulting from the esterification step by the theoretical mass of water produced, considering that all the acid functions of the DMFC compound have reacted.

[0036] The content of DEG units in the polyester formed is less than 4 mol%, or even less than 3 mol%, preferably less than 2 mol%. Under the conditions of the invention, in particular with the use of an increasing temperature, it has been observed that the addition of anti-DG unit formation agents as described in application WO2015 / 137805, for example ammonium compounds, in particular tetraalkylammonium compounds, did not provide any additional effect. Thus, the method according to the invention preferably does not comprise the addition of anti-DG unit formation agents. By applying all of the preferred conditions, the content of DEG units in the polyester obtained at the end of the method according to the invention is below the limit of detectability by NMR type measurement. Polycondensation step

[0037] The PEF synthesis process implemented in the yarn according to the invention comprises a polycondensation step in a molten medium carried out at a temperature in the range from 220°C to 250°C and a pressure of less than 100 mbar.

[0038] At the end of the esterification step, the pressure is gradually lowered for a period of between 60 and 120 min, preferably between 80 and 100 min to reach the operating pressure of the polycondensation step. When the pressure is less than 400 mbar, preferably less than 300 mbar and very preferably less than 200 mbar, the temperature of the reaction medium is increased until the initial operating temperature of the polycondensation step is reached. The increase in temperature to the initial operating temperature of the polycondensation step is carried out over a period of between 15 and 45 min.

[0039] The use of a low operating pressure, and in particular the depressurization phase, makes it possible to gradually evacuate the ethylene glycol (EG) present in the reaction system. Preferably, the polycondensation step is carried out at a temperature increasing in the range from 220°C to 250°C. Preferably, the temperature increases in the range from 225°C to 240°C in steps within a range from 2 to 10°C. Preferably, each step lasts independently from 15 min to 2h30. The applicant has observed that the application of an increasing temperature profile during the polycondensation step makes it possible to limit the formation of DEG units in the polyester.

[0040] For example, the polycondensation step can be carried out for 1 h at 230°C, then 1 h at 240°C. In this case, each stage, namely the temperature difference between two tem successive operating temperatures, is 10°C and the respective duration of each of the two stages is 1h and 2h.

[0041] Thus, the use of increasing temperatures for the esterification and polycondensation steps is particularly advantageous in terms of controlling the structure of the polyester obtained. In particular, they make it possible to obtain a polyester which comprises a quantity of decarboxylated chain ends below the detectability threshold.

[0042] The polycondensation step is carried out for a period preferably ranging from 1 to 5 hours, preferably ranging from 2 to 4 hours. This step is carried out under low pressure, preferably at a pressure below 100 mbar, very preferably at a pressure below 50 mbar. These particular conditions make it possible to maintain a very low content of DEG units in the polyester, or even contents below the limits of detectability.

[0043] The polycondensation step is carried out with a catalyst content ranging from 100 to 1000 ppm, preferably ranging from 150 to 500 ppm, and very preferably ranging from 200 to 450 ppm. The catalyst is generally added to the reaction system during the esterification step. A catalyst addition, identical or different from that used during the esterification step, can be made if necessary during the polycondensation step.

[0044] The polyester obtained at the end of this step, called polycondensate, is then cooled rapidly by contact with water and cut into granules. This rapid contact makes it possible to limit the agglomeration of the granules with each other. The granulation step is carried out so as to form granules that are substantially homogeneous in size, in order to facilitate subsequent operations.

[0045] The granules are then dried at a temperature ranging from 80°C to 100°C at a pressure less than or equal to atmospheric pressure under an inert atmosphere, for example under a nitrogen atmosphere.

[0046] The polyester obtained at the end of the polycondensation step is substantially amorphous.

[0047] The polyester obtained at the end of the polycondensation step has an intrinsic viscosity of between 0.35 and 0.50 dL / g. This intrinsic viscosity is linked to the molar mass of the polyester, and is all the greater as the molar mass of the polyester is high. Preferably, the intrinsic viscosity of the polyester is between 0.4 and 0.50 dL / g. Crystallization stage

[0048] Following the shaping of the polyester in the form of granules, a crystallization step is carried out at a temperature between the crystallization temperature and the melting temperature of the polyester. This step makes it possible to increase the crystallinity of the polyester.

[0049] In order for crystallization to take place, the crystallization step is carried out at a temperature ranging from 150°C to 210°C and for a duration ranging from 15 min to 2h30, preferably carried out at a temperature ranging from 180°C to 200°C for 20 min to 1h30. Post-condensation step in the solid state

[0050] In order to increase the average molar mass of the polyester obtained and its melting temperature, a post-condensation step in the solid state is carried out following the crystallization step. This step is carried out by heating the polyester to a temperature close to and below its melting temperature.

[0051] Thus, the solid phase post-condensation step is carried out at a temperature increasing in the range from 210°C to 260°C, preferably in the range from 210°C to 250°C and very preferably in the range from 210 to 235°C for a period of time ranging from 24 h to 72 h. Preferably, the temperature of the solid phase post-condensation step is increased in steps within a range from 2 to 10°C.

[0052] By carrying out this step with a temperature increasing in the range from 210°C to 260°C, preferably in the range from 220°C to 250°C, preferably by increasing this temperature in steps within a range from 2 to 10°C, preferably from 3 to 5°C, the increase in the molar mass and the melting temperature of the polyester obtained is maximized. In addition, and surprisingly, the melting zone, i.e. the temperature range visible on the thermogram obtained by DSC according to the method described later in the present document in which the melting is observed, is significantly reduced compared to the polyesters obtained according to the methods of the prior art.

[0053] At the end of the post-condensation step in the solid state, the intrinsic viscosity of the polyester is increased, and is preferably between 0.65 and 1.05 dL / g, preferably between 0.65 and 0.90 dL / g.

[0054] The characteristics of the polyester synthesized according to the process described above make it particularly suitable for being spun to obtain a yarn according to the invention. In particular, its high molar masses, melting temperature and intrinsic viscosity make it possible to obtain, by spinning it under particular conditions described below, a yarn whose thermomechanical characteristics are particularly advantageous. The very high melting temperature of the polyester obtained in particular allows the yarn produced from this polyester under the conditions of the invention to be incorporated into a tire and to withstand the severe curing conditions imposed during tire crosslinking operations.

[0055] The granules are then used to form a yarn according to the invention by a melt spinning process comprising at least the following steps: • A step of spinning the granules by melting / extrusion; • A yarn stretching stage; • A winding step on a receiving reel. Method of manufacturing the yarn according to the invention

[0056] The invention also relates to a method for manufacturing a yarn made of PEF filaments comprising at least the following steps:

[0057] a. A spinning step in which PEF pellets are fed to an extruder in which they are melted and extruded into filaments through a die, then grouped together as an undrawn yarn;

[0058] b. A step of drawing the undrawn yarn on at least two pairs of drawing buckets,

[0059] wherein the ratio of the yarn speed at the first pair of godets drawing on the average speed of the filaments at the outlet of the die ranges from 3 to 59, preferably from 10 to 25. Pellet spinning stage by melting / extrusion

[0060] An extruder comprising a feed hopper, a heated extrusion screw, a volumetric pump and a die comprising a multitude of holes whose diameter ranges from 250 to 800 μm, preferably from 300 to 500 μm, making it possible to produce filaments whose diameter ranges from 10 to 70 μm, preferably from 30 to 70 μm and preferably from 40 to 60 μm is fed with previously dried polymer granules, either in line at the inlet of the screw, or in an oven in order to evacuate any residual moisture which would be harmful to the properties of the filaments by causing degradation of the polymer, in particular by hydrolysis of the chains, induced by the heat during passage through the die.

[0061] The polymer is melted, sheared and pushed by a temperature-controlled extrusion screw to a volumetric pump whose flow rate is chosen to feed the die. The extrusion temperature ranges from 240°C to 300°C, preferably from 260°C to 290°C. The extrusion temperature is adjusted to a temperature above the melting temperature of the polymer to ensure its melting, preferably at a temperature at least 20°C above the melting temperature of the polymer, and preferably at least 30°C above the melting temperature of the polymer.

[0062] The molten polymer arrives in the die under pressure and at high temperature. After passing through a filter, the polymer is spun by passing through the holes of the die from which it flows by gravity with a certain material flow rate depending on the flow rate of the pump, forming a filament.

[0063] The filaments which flow in several distinct flows in the molten state are cooled by an air flow at a temperature ranging from 10 to 30°C, preferably from 15 to 25°C, for example at room temperature, orthogonal. Yarn drawing stage

[0064] These filaments are then grouped together so as to form a pre-stretched multi-filament yarn and pass through a spraying or impregnation step with a sizing solution, the function of which is to limit friction or rubbing between filaments and on the spinning machine in order to reduce the formation of static electricity and also to facilitate the subsequent steps of transformation of the multifilament.

[0065] The pre-stretched multi-filament yarn is wound several turns around a first pair of godets rotating at room temperature. A pair of godets consists of two cylinders whose axes are not entirely parallel, the surface of which is covered with a coating suitable for driving without degradation of the yarn. They are rotated in the same direction and at the same speed and their temperature can generally be regulated. In practice, the yarn is wound around the two godets over several turns. Over this portion of its path, contact with the godets modifies its temperature, which is reduced in the case of this first pair, but it is not stretched.

[0066] The yarn passes from one pair of buckets to the next along the same trajectory of winding several turns around each pair, until a final pair feeds a storage bobbin.

[0067] The yarn can also be stored on a storage reel as an intermediate step between two drawing stages. This is called drawing in two (or more) stages.

[0068] Each pair of godets may have a different temperature and have a different speed from that of the previous pair, chosen according to the level of drawing desired at each stage. It is the difference in rotation speed between two successive pairs which induces the so-called "cold" drawing, as opposed to the so-called "melt" drawing of the filaments during their gravitational fall between the outlet of the die and the first pair of godets. The speed between two successive pairs of godets may be slightly lower so as to relax the yarn and thus limit its standard contraction, the rotation speeds increasing overall in the direction of travel of the yarn.

[0069] Preferably, each pair of cups, with the exception of the first which is at room temperature, is regulated at a temperature ranging from 30°C to 180°C, preferably ranging from 40°C to 150°C.

[0070] Preferably, each pair of godets except the first is regulated at a temperature above 100°C, preferably between 100°C and 150°C. Such temperature regulation makes it possible to obtain a yarn having a very good elongation at break without degrading the tenacity. Below these values, yarns having a very good tenacity can be obtained, with a lower elongation at break.

[0071] Preferably, the step of drawing the yarn is carried out on a succession of 2 to 10 pairs of godets, preferably 3 to 6 pairs of godets, very preferably 4 to 6 pairs of godets.

[0072] Preferably, the rate of drawing of the yarn in step b), corresponding to the ratio of the speed of the last pair of godets to the speed of the first pair of godets, is between 1.5 and 6.

[0073] At the exit of the last pair of buckets, the yarn is cut onto a receiving reel. Description of the figures

[0074] [Fig.l] [Fig.l] schematically represents a possible arrangement of the method according to the invention.

[0075] PEF granules are fed via a feed hopper (A) into a heated extrusion screw (B) in which they are melted and pushed towards a volumetric pump (C), which feeds a die (D). This die comprises several holes. By passing through these holes, the molten polymer forms filaments which flow by gravity and are cooled by an orthogonal air flow.

[0076] These filaments are grouped into a yarn which is wound several turns around a first pair of cups at room temperature (EI). The speed of the filament at the outlet of the die being lower than the speed of the yarn on the first pair of cups, the yarn has therefore undergone a first drawing.

[0077] The yarn passes from one pair of buckets to the next (E1, E2, E3, E4) along the same trajectory of a winding of several turns around each pair, up to a last pair (E5) which feeds a storage reel (F).

[0078] The scheme shown here includes, but is not limited to, a total of five pairs of godets. This is a so-called "one-step" drawing scheme because the yarn is drawn from the die outlet to the storage bobbin without intermediate storage on a bobbin. Intermediate storage could be envisaged after the first pair of godets, or between subsequent pairs of godets. Measurement methods Secant modulus

[0079] The secant modulus is determined from a toughness / elongation curve obtained during a tensile test carried out in accordance with ASTM D885-3 in de ending the slope of the line passing through the origin and the point of the curve cor corresponding to a tenacity of 3 cN / dTex.

[0080] The tenacity 3cN / dTex is converted into strength by multiplying the former by the titre tested yarn FF a t”I titrsïdTcx p] = 3*.........ioo......

[0081] We then calculate the slope of the line passing through the origin: Forcf [AQx 100 elongation at 3eN.dTex'\,:>l}

[0082] The result obtained is divided by the surface area of ​​the yarn tested, to obtain a value expressed in Pascal: sw. face [)n2] = Title

[0083] Knowing that 1 Tex = 1 g / lOOOm = 106 kg / m.

[0084] p being the density of the material considered, we will take 1.38g / cm3 for PET and 1.48g / cm3 for PEF.

[0085] Module [GPa] = —...... ? L 3 surface x 10 Examples Manufacture of PEF granules

[0086] A transesterification step is fed with a composition comprising dimethylfuranedicarboxylate (DMF) and ethylene glycol (EG) with an EG / DMF molar ratio equal to 1.7. This composition is placed in the presence of 400 ppm of titanium tetrabutoxide (TBT) catalyst.

[0087] The transesterification step is carried out at 1.5 bar with a temperature ranging from 160°C to 194°C with a temperature ramp of +0.2°C / min for 3 h, the highest temperature being maintained once reached.

[0088] At the end of this step, a prepolymer is obtained in which the presence of DEG units is not detectable. The transesterification rate is 82%.

[0089] The pressure of the reaction medium is lowered to 200 mbar in 20 min while initially maintaining the temperature at 194°C. When the pressure reaches 200 mbar, the temperature is increased to reach 230°C in 30 min while continuing to lower the pressure. Finally, 40 min after reaching 230°C, i.e. when P<1.3 mbar, the polycondensation step is started, during which the temperature is maintained at 230°C for 1 h, then raised to 240°C and maintained for 1 h.

[0090] At the end of the polycondensation step, the polycondensate is cooled rapidly by contacting it with water and cut into granules.

[0091] The granules obtained are then dried for 5 hours at 100°C and then treated in a crystallization step in which they are brought to a temperature of 190°C for 1 hour 30 minutes.

[0092] At the end of crystallization, a post-condensation step is carried out in the solid state by bringing the granules to a temperature of 217°C for 6 hours, then to a temperature of 227°C for 34 hours, under a flow of nitrogen.

[0093] The polyester obtained at the end of this step has the following characteristics: • Intrinsic viscosity (IV): 0.71 dL / g • Crystallinity rate: 52% • Melting temperature: 234.5°C

[0094] The melting temperature measured by applying a temperature ramp of 20 K / min as recommended in the ISO 11357-3 standard of March 2018 is 242.5°C. Spinning of PEF granules

[0095] The pellets are spun according to the process described below.

[0096] The granules are fed into a screw extruder in which they are gradually heated. A volumetric pump feeds the molten polymer into a die comprising 4 circular orifices, the temperature at the die being equal to Tfliage.

[0097] The 4 filaments are grouped into a yarn which is drawn over a series of 5 pairs of cups and then cut onto a receiving reel at a speed equal to the winding speed.

[0098] The applied drawing ratio, corresponding to the ratio of the speed of the last pair of godets to the speed of the first pair of godets, as well as the other parameters of the spinning process, are indicated in Table 1.

[0099] [Tables 1] Gratified Process parameters Mn and / bu Mw fg / OMlî T fii-sge T” Drawing buckets ('CJ Drawing rate Speed ​​ernbobtRage (m / rnihj Pake! Pair 2 Pake? Pake 4 Pair 5 TeK 1 MP = 496«* Mw = 1091«* 270 Amb. •25 125 105 43 6 150*0 Test 2 = 1091«} 230' Amb *25 125 105 45 6 1500

[0100] The characterizations carried out on the yarn obtained are presented in Table 2. These characterizations are carried out from a sample of yarn taken from the receiving reel.

[0101] [Tables2] Yarn characterization Yarn count (dTex) Number of filaments in the yarn Tenacity (cN / dTex) at max force {%) Energy at break (cN / dTex) Sequential modulus at 3cN / dTex Filament melting [°C] Test 1 100 4 6 16 96 21.0 216 Test 2 112 4 6 13 75 19.8 216

[0102] The yarns shown in Table 3 are manufactured using the same process as those in Table 1. The temperatures of the pairs of drawing cups were varied. "Amb" means that the first pair of cups is at room temperature, i.e. approximately 25°C

[0103] [Tables3] Pellets Process parameters Mo and / or MW TfqiSage T” Drawing cups Drawing ratio Winding speed Pair! Pair 2 Pair 3 Pair 4 Pair 5 Tes'? 3 2?$ Arnb 12s 115 45 45 5: 15M Test 4 272 Amt lis iÔS 45 15M Test 5 27'3 Amb îZ5 lie 145 S55: 5

[0104] The characterizations of these yarns, established from samples collected on the receiving coil, are reported in Table 4.

[0105] [Tables4] Yarn characterization Title (dTex) Number of filaments in the yarn Tenacity (cN / dTex) at max force (%} Energy at break [cN / dTex] Test 3 72 4 4 31 130.2 Test 4 71 4 4 37 155.4 Test 5 70 4 4 40 160

[0106] The use of temperatures above 100°C makes it possible to improve the elongation at break of the yarns, without significantly impacting their tenacity.

Claims

Claims

1. A yarn comprising polyethylene-2,5-furanedicarboxylate (PEF) filaments having a tenacity at break of at least 4 cN / dTex and a breaking energy, defined as the product of the tenacity at break in cN / dTex and the elongation at break in %, of at least 40 cN / dTex, the tenacity at break and the elongation at break being determined according to ASTM D885-03.

2. Yarn according to the preceding claim having a secant modulus at 3 cN / dTex at least equal to 13 GPa, preferably at least equal to 15 GPa.

3. Yarn according to any one of the preceding claims having an elongation at break greater than 6%, preferably at least equal to 8%.

4. A yarn according to any preceding claim wherein the PEF constituting the PEF filaments of the yarn has a melting temperature of at least 215°C.

5. A yarn according to any preceding claim made of PEF filaments.

6. A method of manufacturing a yarn according to claim 5 comprising at least the following steps: a. A spinning step in which PEF granules are fed to an extruder in which they are melted and extruded into filaments through a die and then grouped together as an undrawn yarn; b. A step of drawing the undrawn yarn over at least two pairs of drawing cups, wherein the ratio of the yarn speed at the first pair of drawing cups to the average speed of the filaments leaving the die is from 10 to 25.

7. Manufacturing method according to claim 6 wherein the extrusion temperature in step a) ranges from 240°C to 300°C, preferably from 260°C to 290°C.

8. A manufacturing method according to any one of claims 6 to 7 wherein each pair of drawing cups, except the first pair, is regulated at a temperature above 100°C, preferably between 100°C and 150°C.

9. Manufacturing method according to any one of claims 6 to 8 wherein the stretch ratio of the yarn in step b) is between 1.5 and 6.

10. Manufacturing method according to any one of claims 6 to 9 in which the step of drawing the yarn is carried out on a succession of 2 to 10 pairs of godets, preferably 3 to 6 pairs of godets, very preferably 4 to 6 pairs of godets.

11. Manufacturing process according to any one of claims 6 to 10 in which the PEF granules are obtained by a process successively comprising: • A step of esterification of a composition comprising a dimethyl-2,5-furanedicarboxylate compound, denoted DMF, said composition also comprising ethylene glycol, denoted EG, this esterification step being carried out at a temperature increasing in the range from 150°C to at least 185°C with an EG / DMF molar ratio ranging from 3 to 1.3 in the presence of a Lewis acid catalyst; • A step of polycondensation in a molten medium carried out at a temperature increasing in the range from 220°C to 250°C and a pressure of less than 100 mbar so as to obtain a polyester.

12. A textile article comprising at least one yarn according to any one of claims 1 to 5 or a yarn prepared by a process according to any one of claims 6 to 11.

13. A reinforced product comprising a yarn according to any one of claims 1 to 5 or a yarn prepared according to any one of claims 6 to 11 embedded in a polymeric matrix.

14. Reinforced product according to the preceding claim selected from transmission belts, conveyor belts, inflatable articles and wheel tires.

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