Method for producing an elastic yarn by means of melt extrusion spinning

Abstract

The present invention relates to a method for producing an elastic yarn by means of melt extrusion spinning using a spinning machine (1) comprising an extruder (2) and a spinning pack (3) comprising at least one spinneret (19), the method comprising at least the following steps: a preliminary step of cold drawing the yarn (20) at the outlet of the spinneret (19), followed by a step of hot drawing the yarn (20) and subsequently a step of cold drawing the yarn (20). The invention also relates to a textile comprising such an elastic yarn and to a facility configured to carry out this method.

Description

[0001] DESCRIPTION

[0002] TITLE: Process for manufacturing an elastic thread by melt spinning extrusion

[0003] The present invention relates to a method for manufacturing a recyclable elastic thread, usable in particular for the manufacture of textiles and footwear.

[0004] Elastic textiles have been known for many years. Such textiles can be used, for example, in the sports field, to make clothing such as sports tights, socks, swimsuits, but also shoes. The elasticity of these textiles is generally achieved by means of elastane threads, which can, for example, be present in the textile in a content ranging from 2 to 50% of the total composition of threads and / or fibers of the textile. Elastane is a segmented polyurethane in the form of a copolymer of a soft segment and a hard segment. Elastane thread has a high level of stretch, or elongation: this thread can, for example, be stretched to more than 600% of its original length before breaking.Elastane yarn also has a high recovery power, or elastic return: thus, after being stretched several times, this yarn returns, when the stretching stress is released, to a length very close to its original length, for example a length ranging from 90% to 100% of its original length.

[0005] However, there are several disadvantages to the production and use of spandex yarn.

[0006] According to ADEME (French Environment and Energy Management Agency), the production of 1 kg of elastane yarn generates 21 kg of CO2 equivalent (ADEME Base Impact V2.01). The production of elastane yarn therefore has a relatively high negative environmental impact.

[0007] Furthermore, since elastane is a thermosetting material, it degrades before being melted. Elastane cannot therefore be thermally recycled. Chemical recycling of elastane could be considered, but the necessary use of solvents in such a process generates too high an environmental impact for it to seem reasonable to implement it.

[0008] Therefore, to date in Europe, textiles containing elastane are generally incinerated or landfilled. The impact of these processes on the environment is damaging. Thus, still according to ADEME, 1 kg of incinerated textiles emits 0.4 kg of CO2 equivalent and 1 kg of buried textiles emits 2.2 kg of CO2 equivalent (ADEME Base Impact V2.01).

[0009] Thus, in view of current environmental considerations, there remains a need for recyclable elastic textiles. In this regard, there remains a need for recyclable elastic yarns, which would have elastic properties comparable to, or even superior to, those of existing non-recyclable elastic yarns such as elastane yarns. These recyclable elastic yarns should also be able to be combined with non-elastic yarns that are also recyclable, in order to produce fully recyclable elastic textiles, regardless of the proportion of elastic yarns within said textiles.

[0010] The present invention aims to address this need by providing a method for manufacturing a recyclable elastic thread by the melt extrusion process.

[0011] The present invention relates to a method for manufacturing an elastic yarn by melt spinning using a spinning machine comprising an extruder, a spinning metering pump, a spinning pack comprising at least one die, a cooling system, at least one delivery roller and at least one draw roller, said method comprising at least the following steps:

[0012] A) said extruder is fed with granules of a copolymer with polyamide blocks and polyether blocks, the polyamide blocks being chosen from PA 11, PA 12, PA 1010, PA 1014, their copolymer and their mixture, the polyether blocks being blocks derived from polytetramethylene glycol, the hardness of the copolymer measured according to standard 7619-1 being between 22 and 61 ShD, in order to obtain by extrusion a molten elastomer of the copolymer with polyamide blocks and polyether blocks,

[0013] B) the molten elastomer obtained in step A) is spun within the spinneret of said spinning pack in order to obtain a yarn of the copolymer with polyamide blocks and polyether blocks,

[0014] C) the yarn of the copolymer with polyamide blocks and polyether blocks obtained in step B) is subjected at the outlet of the die to cooling to a temperature strictly lower than the glass transition temperature of said polyamide blocks, for example to a temperature ranging from approximately 10°C to approximately 49°C, preferably ranging from approximately 10°C to approximately 30°C, more preferably ranging from approximately 20°C to approximately 25°C,

[0015] D) the yarn of the polyamide block and polyether block copolymer is subjected to preliminary stretching at the temperature of step C),

[0016] E) the yarn of the copolymer with polyamide blocks and polyether blocks obtained at the end of step D) is subjected to hot drawing at a temperature strictly higher than the glass transition temperature of said polyamide blocks, for example at a temperature ranging from approximately 45°C to approximately 125°C, preferably ranging from 45°C to 120°C, preferably ranging from approximately 50°C to approximately 125°C, more preferably ranging from approximately 90°C to approximately 120°C,

[0017] F) the yarn of the polyamide block and polyether block copolymer obtained at the end of step E) is subjected to cold drawing at a temperature ranging from approximately 10°C to approximately 49°C, ranging from approximately 10°C to approximately 30°C, preferably ranging from approximately 20°C to approximately 25°C.

[0018] In the present application, yarn means any fiber of infinite length. In particular, the yarn may be in the form of monofilaments or multifilaments.

[0019] In the present application, the term glass transition temperature means the temperature below which a polymer is in the glassy (solid) state and above which said polymer exhibits a rubbery state (plastic solid behavior).

[0020] The process according to the invention makes it possible to obtain an elastic thread based on a recyclable copolymer, said elastic thread having excellent elastic properties. In particular, the elastic thread obtained by the process according to the invention has an elongation, or elongation at break, greater than or equal to 106%, for example greater than or equal to 131%, for example greater than or equal to 164.5%, for example greater than or equal to 180%, for example greater than or equal to 200%, for example approximately 233.3%, measured according to the method described in Example 1 of this document. Similarly, the elastic thread obtained by the process according to the invention has an elastic recovery of up to 96.6%, measured according to the method described in Example 1 of this document. Furthermore, the elastic thread obtained by the process according to the invention has a particularly low permanent deformation, for example of the order of 2.5%, measured according to the method described in Example 1 of this document.

[0021] Another aspect of the invention relates to an elastic thread obtainable by the method according to the invention, having an average elongation at break, measured according to standard DIN ISO 13895, greater than or equal to approximately 106%, preferably greater than or equal to approximately 131%, preferably greater than or equal to 164.5%, preferably greater than or equal to 180%, for example approximately 233.3%, and / or having an elastic return, measured according to standard DIN 53835-2, greater than or equal to approximately 86.5%, preferably greater than or equal to 91.8%, preferably greater than or equal to 94%, preferably greater than or equal to 96.3%, for example approximately 96.6%.

[0022] Thus, one aspect of the invention relates to an elastic thread capable of being obtained by the method according to the invention, having an average elongation at break, measured according to standard DIN ISO 13895, of approximately 106%, and an elastic return, measured according to standard DIN 53835-2, of approximately 86.5%.

[0023] One aspect of the invention relates to an elastic thread obtainable by the method according to the invention, having an average elongation at break, measured according to standard DIN ISO 13895, of approximately 131%, and an elastic return, measured according to standard DIN 53835-2, of approximately 94%.

[0024] One aspect of the invention relates to an elastic thread obtainable by the method according to the invention, having an average elongation at break, measured according to standard DIN ISO 13895, of approximately 164.5%, and an elastic return, measured according to standard DIN 53835-2, of approximately 91.8%.

[0025] One aspect of the invention relates to an elastic thread obtainable by the method according to the invention, having an average elongation at break, measured according to standard DIN ISO 13895, of approximately 180%, and an elastic return, measured according to standard DIN 53835-2, of approximately 96.3%.

[0026] One aspect of the invention relates to an elastic thread obtainable by the method according to the invention, having an average elongation at break, measured according to standard DIN ISO 13895, of approximately 233.3%, and an elastic return, measured according to standard DIN 53835-2, of approximately 96.6%.

[0027] Another aspect of the invention relates to a textile comprising at least one elastic thread capable of being obtained by the method according to the invention.

[0028] Another aspect of the invention relates to a method for recycling a textile comprising at least one elastic thread according to the invention, and at least one thermoplastic thread, preferably made of polyamide, characterized in that it comprises the following steps:

[0029] - i) said textile is ground to obtain particles,

[0030] - ii) the particles from step ii) are then melted in an extruder in order to obtain granules of said mixture.

[0031] The recycling process may further comprise the following step iii):

[0032] - iii) a recycled yarn is spun by melt extrusion from the pellets obtained in step ii).

[0033] The granules from step ii) constitute raw materials for all applications, particularly textiles.

[0034] In this application, the term "textile" means any material made from fibers or yarns. In particular, the textile may be an arrangement of fibers and / or yarns in the form of a knit, a woven, a non-woven, a braid and combinations thereof.

[0035] Another aspect of the invention relates to a garment comprising at least one elastic thread capable of being obtained by the method according to the invention.

[0036] Another aspect of the invention is an installation configured to implement the method according to the invention, said installation comprising:

[0037] - a spinning machine comprising an extruder, a spinning metering pump, a spinning pack comprising at least one spinneret,

[0038] - a cooling system located at the outlet of the die,

[0039] - at least one delivery roller placed at the outlet of the cooling system,

[0040] - at least one first stretching roller, arranged downstream of the delivery roller, - at least one second stretching roller, arranged downstream of the first stretching roller,

[0041] - a heating means arranged between the delivery roller and the first stretching roller.

[0042] In the present application, "upstream" means the direction towards the place of "birth" or extrusion of the yarn (spinning pack) and "downstream" means the opposite direction, in other words the direction towards the place of storage of the elastic yarn, once the yarn has undergone all the desired stretching.

[0043] In one embodiment, the installation may comprise a winding roller downstream of the delivery roller in order to store the wire resulting from the preliminary cold drawing step. The wire resulting from this winding roller is then, in a second step, passed over the first drawing roller.

[0044] The method for manufacturing an elastic thread according to the invention is based on the melt spinning technique using the extrusion-spinning of a molten polymer within an extruder and then a spinning pack. In this respect, the different stages of the process as described below are carried out continuously.

[0045] Thus, in a first step of the process according to the invention, an extruder is fed with granules of a copolymer with polyamide blocks and polyether blocks, the polyamide blocks being chosen from PA 11, PA 12, PA 1010, PA 1014, their copolymer and their mixture, the polyether blocks being blocks derived from polytetramethylene glycol, the hardness of the copolymer measured according to standard 7619-1 being between 22 and 61 ShD, in order to obtain by extrusion a molten elastomer of the copolymer with polyamide blocks and polyether blocks.

[0046] The nomenclature used to define polyamides is described in ISO 1874-1:2011 "Plastics - Polyamide (PA) materials for molding and extrusion - Part 1: Designation", particularly on page 3 (tables 1 and 2) and is well known to those skilled in the art.

[0047] It is further specified that the expressions "between. . . and. . ." and "from. . . to. . ." used in this description must be understood as including each of the limits mentioned.

[0048] The word "polyamide" covers both homopolyamides and copolyamides.

[0049] The copolymer used in the process according to the invention has a hardness measured according to standard 7619-1 of between 22 and 61 ShD, preferably between 22 and 55 ShD, preferably between 22 and 40 ShD.

[0050] The polyamide blocks can be chosen from PA 11, PA 12, their copolymer and their mixture. Preferably, the polyamide blocks are PA 11 blocks. A copolymer that can be used in the process according to the invention is the product sold under the trade name “PEBAX® RNEW 35R53 SP 01” by the company Arkema. This elastomeric copolymer has the following characteristics: a density of 1020 kg / m 3 , measured according to ISO 1183, a hardness of 25 shore D, at 15 seconds, measured according to ISO 7619-

[0051] 1, a melting point of 135°C, measured according to ISO 1 1357-1 / -3, a content of bio-sourced component, such as polyamide PA 11, of 29%, measured according to ASTM D6866.

[0052] Another copolymer that can be used in the process according to the invention is the product sold under the trade name “PEBAX® 7033 SP 01” by the company Arkema. This elastomeric copolymer has the following characteristics: a density of 1010 kg / m 3 , measured according to ISO 1183, a hardness of 61 shore D, at 15 seconds, measured according to ISO 7619-

[0053] 1, a melting point of 172°C, measured according to ISO 1 1357-1 / -3.

[0054] Another copolymer that can be used in the process according to the invention is the product sold under the trade name “PEBAX® 2533 SA 01” by the company Arkema. This elastomeric copolymer has the following characteristics: a density of 1000 kg / m 3 , measured according to ISO 1183, a hardness of 22 shore D, at 15 seconds, measured according to ISO 7619-

[0055] 1, a melting point of 134°C, measured according to ISO 1 1357-1 / -3.

[0056] To carry out the first step of the process according to the invention, the copolymer may be dried beforehand in order to reduce the moisture content of the copolymer to less than 200 ppm. The moisture content characterization tests may, for example, be carried out using the Karl-Fischer titration method.

[0057] The spinning machine comprises an extruder, for example a screw extruder, a spinning metering pump, and a spinning pack. The spinning pack typically comprises a die. The spinning pack may also typically contain a distribution plate, a metal filter, and filter sand. The extruder and the spinning pump are purged before being fed with copolymer. The spinning machine also comprises a cooling system, at least one delivery roller, for example a pair of delivery rollers, and at least one draw roller, for example a pair of draw rollers. The draw rollers may or may not be heatable. The spinning machine also preferably comprises a winding roller for storing the produced yarn.In a first step, step A) of the process according to the invention, the polyamide block and polyether block copolymer granules as described above are introduced into the extruder in which they are melted. At the outlet of the extruder, a molten elastomer of the polyamide block and polyether block copolymer is obtained. In a second step, step B) of the process according to the invention, the molten elastomer obtained in step A) is spun within the spinneret of the spinning pack in order to obtain a yarn of the polyamide block and polyether block copolymer. The spinning metering pump controls the flow of the elastomer to the spinneret of the spinning pack. The metal filter and the filter sand can be used to remove impurities. The elastomer is injected into the spinneret. At the outlet of the spinneret, a yarn of the polyamide block and polyether block copolymer is established.

[0058] According to a third step, step C) of the process according to the invention, the yarn of the copolymer with polyamide blocks and polyether blocks is subjected at the outlet of the die to cooling to a temperature strictly lower than the glass transition temperature of said polyamide blocks, for example to a temperature ranging from approximately 10°C to approximately 30°C, preferably ranging from approximately 20°C to approximately 25°C.

[0059] Wire cooling can be carried out by air or water quenching, depending on the thickness of the wire and the efficiency of the cooling system. In the case of water quenching, the wire may, for example, be passed through a tank filled with water at a temperature of 20-25°C.

[0060] In the case of air cooling, the wire may be passed through a current of cold air, for example brought to a temperature ranging from 10 to 25°C.

[0061] During the cooling stage, the wire solidifies.

[0062] According to a fourth step, step D) of the method according to the invention, the wire is subjected to a first stretching, or preliminary stretching, at the temperature of step C). This preliminary cold stretching makes it possible to give the wire a first elasticity.

[0063] In one embodiment, the yarn leaving the spinneret of the spinning pack of step B) according to a linear speed of the spinning metering pump VP, the yarn is drawn in step D) by passing over a delivery roller having a linear speed of the delivery V1, V1 being chosen such that the rate D1 of the preliminary drawing is greater than or equal to 2.53, where D1 = V1 / VP. Such a preliminary drawing rate makes it possible to give the yarn significant elasticity while maintaining good tenacity, and therefore good mechanical properties.

[0064] In this application, the term "linear speed" of a pump or a roller, feeder, stretcher or winder, is understood to mean the linear speed of the outer wall of the pump or roller in contact with the wire during the movement of the latter.

[0065] In one embodiment, the yarn obtained at the end of step D) can be stored on a winding roll before being subjected to step E). According to a fifth step, step E) of the process according to the invention, the yarn of the copolymer with polyamide blocks and polyether blocks obtained at the end of step D), whether stored on a winding roll or directly from the delivery roll, is subjected to hot drawing. The temperature of the hot drawing is strictly higher than the glass transition temperature of the polyamide blocks of the copolymer and can range from approximately 40°C to approximately 125°C, preferably ranging from approximately 50°C to approximately 125°C, preferably ranging from approximately 90°C to approximately 120°C. The temperature of the hot drawing can depend on the linear speed of the yarn. For example, this temperature can be approximately 115°C. To do this, the wire is brought through or in contact with a heating means brought to the desired temperature.For example, the heating means may be a furnace heated to the desired temperature. Alternatively or in combination, the heating means may comprise one or more drawing rolls heated to the desired temperature. For example, the hot drawing temperature may be 115°C when the heating means is a furnace located between two pairs of cold drawing rolls. In another example, the hot drawing temperature may be 45°C when the heating means comprises hot drawing rolls (e.g. heated to 45°C). Hot drawing makes it possible to reduce the thickness of the wire, in other words to increase its fineness.

[0066] In one embodiment, the wire is drawn in step E) by passing over a first drawing roller having a linear drawing speed V2, V2 being chosen such that the rate D2 of the hot drawing is less than or equal to 8, where D2 = V2 / V1. When the heating means is an oven through which the wire passes, the oven can thus be located between the delivery roller and the first drawing roller. Alternatively, the first drawing roller can be a heatable roller brought to the desired temperature. Such a hot drawing rate makes it possible to give the wire a significant fineness while retaining an interesting elasticity.

[0067] According to a sixth step, step F) of the process according to the invention, the yarn of the polyamide block and polyether block copolymer obtained at the end of step E) is subjected to cold drawing. The temperature of this cold drawing can range from approximately 20°C to approximately 49°C, preferably from approximately 20°C to approximately 25°C. This second cold drawing makes it possible to give the yarn additional elasticity.

[0068] In one embodiment, the wire is drawn in step F) by passing over a second drawing roller having a linear drawing speed V3, V3 being chosen such that the cold drawing rate D3 is greater than or equal to 1, where D3 = V3 / V2. Such a drawing rate at this step makes it possible to obtain a wire having very good elasticity.

[0069] In one embodiment, D1 = 5.07. In one embodiment, D1 = 5.07 and D2 = 4. In one embodiment, D1 = 5.07, D2 = 4 and D3 = 1. The resulting yarn has very good elasticity while having good fineness. In one embodiment, the second drawing roller is a winding roller. The yarn is thus wound onto this roller and can be stored.

[0070] In one embodiment, the stored wire may subsequently be subjected to further stretching, also called post-stretching, to improve its elastic recovery.

[0071] In one embodiment, the method according to the invention further comprises the following step G):

[0072] - G) the yarn of the copolymer with polyamide blocks and polyether blocks obtained at the end of step F) is subjected to post-stretching at a temperature strictly lower than the glass transition temperature of said polyamide blocks, for example at a temperature ranging from approximately 10°C to approximately 30°C, preferably ranging from approximately 20°C to approximately 25°C.

[0073] During step G), the wire can be post-stretched by passing over a first post-stretching roller having a linear speed V4 then over a second post-stretching roller having a linear speed V5, V4 and V5 being chosen such that the post-stretching rate D4 is greater than or equal to 1.65, where D4 = V5 / V4.

[0074] The method may further comprise the following step H):

[0075] - H) the yarn of the copolymer with polyamide blocks and polyether blocks obtained at the end of step G) is subjected to relaxation at a temperature strictly lower than the glass transition temperature of said polyamide blocks, for example at a temperature ranging from approximately 10°C to approximately 30°C, preferably ranging from approximately 20°C to approximately 25°C.

[0076] In step H), the wire can be relaxed by passing over a winding roller having a linear speed V6 chosen such that V6 / V4 ranges from 1 to 1.50, preferably from 1 to 1.25, more preferably from 1.00 to 1.05.

[0077] The installation according to the invention can thus further comprise: at least one first post-stretching roller arranged downstream of the winding roller, at least one second post-stretching roller arranged downstream of the first post-stretching roller.

[0078] In one embodiment, the yarn is heat-set at the end of step F) or after post-stretching, in particular according to step G) described above, or after relaxation, in particular according to step H) described above. Heat-setting allows the yarn to retain its elastic and mechanical properties over the long term, for example for one year. Heat-setting can, for example, be carried out at a temperature strictly higher than the glass transition temperature of said polyamide blocks, for example at a temperature ranging from approximately 70°C to approximately 90°C, preferably approximately 80°C. Other characteristics and advantages of the present invention will appear even more clearly on reading the following example and the appended drawings in which: [Fig. 1] is a diagram representing a first embodiment of an installation making it possible to implement the method according to the invention, [Fig.2] is a graph showing the results of elastic return and permanent deformation tests for wires produced using the method according to the invention.

[0079] [Fig. 3a], [Fig. 3b], [Fig. 3c] and [Fig. 3d] are graphs showing the tensile force versus elongation curves of the wires of Example 1,

[0080] [Fig. 4a], [Fig. 4b], [Fig. 4c] and [Fig. 4d] are graphs showing the hysteresis curves obtained for the wires of Example 1,

[0081] [Fig. 5] is a diagram representing a second embodiment of an installation making it possible to implement the method according to the invention,

[0082] [Fig. 6] is a graph showing the tensile force versus elongation curve for the wire of Example 2,

[0083] [Fig. 7] is a graph showing the hysteresis curve obtained for the wire of Example 2,

[0084] [Fig. 8] is a diagram showing an installation for implementing the post-stretching and relaxation steps,

[0085] [Fig. 9a] and [Fig. 9b] are graphs showing the tensile force versus elongation curves of the wires in Example 3.

[0086] Referring to Figure 1, a first embodiment of an installation 100 is shown for implementing the method according to the invention. The installation 100 comprises a spinning machine 1 comprising an extruder 2 and a spinning pack 3. The installation 100 also comprises a tank 4 filled with water 5, a pair 6 of delivery rollers 6a, a pair 7 of stretching rollers 7a and a winding roller 8. The installation 100 finally comprises a furnace 9 located between the delivery rollers 6 and the stretching rollers 7a.

[0087] The steps of the method according to the invention will now be described with reference to Figure 1.

[0088] We have 10 granules of a copolymer with polyamide blocks and polyether blocks sold under the trade name "PEBAX RNEW 35R53 SP 01" by the company Arkema. The polyamide blocks of this copolymer are PA 11 blocks, the polyether blocks being blocks derived from polytetramethylene glycol.

[0089] This elastomeric copolymer has the following characteristics:

[0090] - a density of 1020 Kg / m3, measured according to ISO 1183 standard,

[0091] - a hardness of 25 shore D, at 15 seconds, measured according to the ISO 7619-1 standard, - a melting point of 135°C, measured according to the ISO 11357-1 / -3 standard,

[0092] - a polyamide PA 11 content, which is a bio-sourced polyamide, of 29%, measured according to the ASTM D6866 standard.

[0093] Prior to their introduction into the extruder, the granules 10 are preferably dried in order to reduce the moisture content of the polymer to a level below 200 ppm. The moisture content characterization tests can, for example, be carried out using the Karl-Fischer titration method. For example, the granules 10 can be dried in an oven at 80°C overnight and under vacuum.

[0094] The granules 10 are then introduced into the extruder 2 by means of a feed hopper 11 at an inlet 2a of the extruder 2. The extruder 2 comprises a body 12 formed by a cylinder in which a worm screw (not shown) rotates. The extruder 2 comprises, within the body 12, heating zones 14, the temperature of these heating zones 14 increasing from the inlet 2a of the extruder 2 to an outlet 2b of the extruder 2. For example, the temperature of the heating zones 14 can vary from 195°C in the vicinity of the inlet 2a of the extruder to 205°C in the vicinity of the outlet 2b of the extruder 2. Within the extruder 2, the granules 10 are kneaded and melted. At the outlet 2b of the extruder 2, a molten elastomer is obtained, which is transported to the spinning pack 3 by means of a transport line formed of a thermally insulated metal pipe 16.The temperature within the transport line is close to that of the outlet temperature of extruder 2, for example 205°C.

[0095] The spinning pack 3 comprises a metering pump 17, a filter 18 and a die 19. The metering pump 17 controls the flow of the molten elastomer to the die 19. In the example shown, the metering pump 17 rotates at a linear speed of 7.5 m / min. The filter 18 is arranged between the metering pump 17 and the die 19 and serves to remove impurities potentially present in the molten elastomer. In the example shown, the filter 18 has a pressure of 40 bar.

[0096] After passing through the filter 18, the molten elastomer is injected into the die 19 at the temperature of the spinning pump 3 which is approximately 210°C. In the example shown, the size of the hole in the die 19 is 0.73 mm and the ratio of the length (L) of the die hole 19 to its diameter (D) is 1 / 4 (ratio L / D). At the outlet of the die 19, a wire 20 is thus established. The wire 20 leaves the die 19 at a linear speed VP corresponding to the linear speed of the metering pump 17. In the present example, since the die 19 has only one hole, the wire 20 is in the form of a monofilament.

[0097] As shown in Figure 1, once it has left the die 19, the wire 20 is brought through the reservoir 4 filled with water 5. The water 5 is at room temperature, in other words at a temperature ranging from approximately 20°C to approximately 25°C. The wire 20 is thus cooled by quenching with water. The cooling of the wire 20 allows the latter to solidify.

[0098] Once cooled, the wire 20 is made to pass over a delivery roller 6a. The delivery roller 6a has a linear speed V1, greater than the linear speed VP. Thus, the wire 20 is subjected, between the exit of the die 19 and the delivery roller 6a, to a preliminary stretching, the rate of which is equal to D1 = V1 / VP. This preliminary stretching takes place cold, and in particular at a temperature strictly lower than the glass transition temperature of the polyamide blocks of the copolymer, for example at a temperature ranging from approximately 20°C to approximately 25°C. Such a preliminary cold stretching makes it possible to give the wire 20 a first elasticity.

[0099] The wire 20 is then brought through the furnace 9 and then, at the outlet of the furnace 9, to pass over a stretching roller 7a. In the example shown, the temperature to which the wire 20 is subjected inside the furnace 9 is approximately 115°C. In other embodiments not shown, the temperature of the furnace could range from 50°C to 120°C.

[0100] The stretching roller 7a has a linear speed V2, greater than the linear speed V1. Thus, the wire 20 is subjected, between the delivery roller 6a and the stretching roller 7a, to hot stretching, the rate of which is equal to D2 = V2 / V1. This hot stretching makes it possible to reduce the thickness of the wire 20, or even to give it a certain fineness.

[0101] The wire 20 is then passed over the winding roller 8. In the example shown, the linear speed V3 of the winding roller is 150 m / min. This linear speed is greater than the linear speed V2. Thus, the wire 20 is subjected, between the drawing roller 7a and the winding roller 8, to a drawing whose rate is equal to D3 = V3A / 2. This drawing takes place outside the furnace 9 at ambient temperature, i.e. at a temperature ranging from approximately 20°C to approximately 25°C. This second cold drawing makes it possible to give the wire 20 additional elasticity.

[0102] In an exemplary embodiment not shown, the winding roller 8 could be a stretching roller, the wire continuing its path towards a subsequent winding roller.

[0103] With reference to Figure 5, a second embodiment of an installation 200 is shown for implementing the method according to the invention. In this Figure 5, the references designating elements identical to those of Figure 1 have been retained.

[0104] The installation 200 comprises a spinning machine 1 comprising an extruder 2 and a spinning pack 3. The installation 200 also comprises a pair 6 of delivery rollers 6a, two pairs 26 of heatable stretching rollers 26a, a pair 27 of relaxation rollers 27a and a winding roller 8.

[0105] The extruder 2 comprises an inlet 2a and an outlet 2b, as well as a feed hopper 11. The extruder 2 comprises heating zones 14, the temperature of these heating zones 14 increasing from the inlet 2a of the extruder 2 towards an outlet 2b of the extruder 2. The polyamide block and polyether block copolymer is the same as that described for Figure 1, namely that sold under the trade name “PEBAX RNEW 35R53 SP 01” by the company Arkema.

[0106] Referring to Figure 5, the copolymer pellets 10 are prepared as described for Figure 1 and are introduced into the extruder 2 through the feed hopper 11.

[0107] Upon exiting extruder 2, the molten elastomer is transported to spinning pack 3 via a transport line 16.

[0108] The spinning pack 3 comprises a metering pump 17, a filter 18 and a spinneret 19. In the installation 200, the metering pump 17 rotates at a linear speed of 65.4 m / min. The spinneret 19 comprises 17 holes: each hole has a size of 0.6 mm and the ratio of the length (L) of a spinneret hole 19 to its diameter (D) is 1 / 4 (L / D ratio). Thus, the yarn 21 which exits the spinneret 19 is in the form of a multifilament yarn. The yarn 21 exits the spinneret 19 at a linear speed VP corresponding to the linear speed of the metering pump 17.

[0109] The wire 21 is cooled by means of air quenching in the form of an air stream 22, the air stream 22 having a temperature less than or equal to 25°C, for example a temperature of approximately 10°C. Preferably, the air stream 22 is applied to the wire 21 according to the arrows F shown in Figure 5 over a height of the wire 21 of several meters, for example over a height of 5 m.

[0110] The installation 200 comprises a device 23 configured to apply a sizing oil to the yarn 21. The installation 200 also comprises a guide 24 adapted to gather the various filaments of the yarn 21 coming from the holes of the die 19. The sizing of the yarn 21 and the guide 24 make it possible to hold together all the filaments coming from the holes of the die 19 in order to form a multifilament yarn 21.

[0111] The wire 21 is then made to pass over a delivery roller 6a, maintained at room temperature, in other words at a temperature ranging from 20 to 25°C. The delivery roller 6a has a linear speed V1, greater than the linear speed VP. Thus, the wire 21 is subjected, between the outlet of the die 19 and the delivery roller 6a, to a preliminary stretching, the rate of which is equal to D1 = V1 / VP. This preliminary stretching takes place cold, and in particular at a temperature strictly lower than the glass transition temperature of the polyamide blocks of the copolymer, for example at a temperature ranging from approximately 20°C to approximately 25°C. Such a preliminary cold stretching makes it possible to give the wire 21 a first elasticity.

[0112] The wire 21 is then brought to pass over a first pair 25 of rollers 25a, which are maintained at room temperature, in other words between 20 and 25°C. The linear speed of the rollers 25a is identical to that of the delivery roller 6a.

[0113] The wire 21 is then passed over two pairs 26 of heatable stretching rollers 26a. The rollers 26a have a temperature of 50°C and a linear speed V2 equal to V1. Thus, the wire 21 is subjected, between the delivery roller 6a and the stretching rollers 26a, to hot stretching, the rate of which is equal to D2 = V2 / V1. This hot stretching makes it possible to reduce the thickness of the wire 21, or even to give it a certain fineness.

[0114] The wire 21 is then passed over a second pair 28 of rollers 28a, which are maintained at room temperature, in other words between 20 and 25°C. The linear speed V3 of the rollers 28a is greater than the linear speed V2. Thus, the wire 21 is subjected, between the stretching rollers 26a and the roller 28a, to a stretching whose rate is equal to D3 = V3 / V2. This stretching takes place at room temperature, i.e. at a temperature ranging from approximately 20°C to approximately 25°C. This second cold stretching makes it possible to give the wire 21 additional elasticity.

[0115] The wire 21 is then passed over a pair 27 of relaxation rollers 27a. The rollers 27a are kept at room temperature, in other words between 20 and 25°C and their linear speed is identical to that of the rollers 28a.

[0116] The wire 21 is then brought to pass over the winding roller 8. The winding roller 8 is kept at room temperature, in other words between 20°C and 25°C. Its linear speed may be slightly lower than V3.

[0117] Referring to Figure 8, there is shown a part of installation 300 for implementing a post-stretching step and a relaxation step, these steps being subsequent to the extrusion, preliminary stretching, hot stretching and cold stretching steps described in Figures 1 and 5 for the yarns (20, 21). The yarn 22 subjected to the post-stretching and relaxation steps described in Figure 8 may be a monofilament yarn such as the yarn 20 obtained according to the method described in Figure 1 or a multifilament yarn such as the yarn 21 obtained according to the method described in Figure 5. The yarn 22 is wound and stored on the winding roller 8.

[0118] The installation part 300 comprises a pair 30 of first post-stretching rollers 30a, a pair 31 of second post-stretching rollers 31a and a final winding roller 32. The installation part 300 is maintained at a temperature strictly lower than the glass transition temperature of the polyamide blocks of the polyamide block and polyether block copolymer forming the yarn 22, for example at a temperature ranging from about 10°C to about 30°C, preferably ranging from about 20°C to about 25°C.

[0119] The wire 22 is brought to pass over a first post-stretching roller 30a and then over a second post-stretching roller 31a. The first post-stretching roller 30a has a linear speed V4 and the second post-stretching roller 31a has a linear speed V5. The linear speed eV5 is greater than the linear speed V4. Thus, the wire 22 is subjected to post-stretching whose rate is equal to D4 = V5 / V4. Such post-stretching makes it possible to give the wire 22 additional elasticity.

[0120] The wire 22 is then brought to pass over the final winding roller 32. The final winding roller 32 has a linear speed V6. This linear speed V6 is preferably slightly higher than the linear speed V4. For example, the ratio V6 / V4 ranges from approximately 1 to 1.50, preferably from 1 to 1.25, more preferably from 1.00 to 1.05. Thus, the wire 22 is subjected to a relaxation step which does not compromise the additional elasticity conferred by the passage of the wire 22 over the post-stretching rollers (30a; 31a).

[0121] The elastic yarns (20, 21, 22) obtained according to the method of the invention described above, in particular in Figures 1, 5 and 8, can be incorporated into a textile or into a garment, such as for example sports tights, swimsuits, etc. The yarns obtained according to the method of the invention are entirely recyclable. Thus, the textiles or garments incorporating these yarns are also recyclable. For example, the yarns obtained by the method according to the invention, the textiles or garments incorporating them can be ground to obtain particles. These particles can be melted to form new granules of copolymers with polyamide blocks and polyether blocks. These granules can be introduced again into an extruder of a spinning machine to form new yarns. This avoids the burial and / or incineration of the elastic yarns.

[0122] EXAMPLES

[0123] EXAMPLE 1

[0124] Several threads 20 were obtained according to the method according to the invention described above with reference to Figure 1, by varying certain parameters of the method. a) Tests carried out:

[0125] Several tests were carried out implementing the process described with reference to Figure 1, in which the following parameters were varied:

[0126] The linear speed V1 of the delivery roller 6a, The linear speed V2 of the delivery roller 7a, The stretching rate D1, The stretching rate D2, The stretching rate D3.

[0127] The fixed parameters were as follows:

[0128] The linear speed VP was 7.4 m / min, The linear speed V3 was 150 m / min, The total stretch rate TD, in other words TD = D1 X D2 X D3, was 20.3. The tests listed in Table 1 below were thus carried out:

[0129] [Table 1]

[0130] Table 1: variations of parameters V1, V2, D1, D2 and D3 b) Evaluation of mechanical properties:

[0131] For each Test 1-4, the following mechanical properties of the yarn obtained after winding on winding roll 8 were measured: average yarn fineness: the yarn fineness is expressed in denier. It is representative of the size (diameter) of the yarn. The fineness was measured in accordance with the method described in DIN EN ISO 13392; average yarn tenacity: the tenacity is expressed in cN / tex. It is representative of the tensile strength of the yarn. It was measured in accordance with the method described in DIN EN ISO 13895; average elongation at break: the average elongation at break is expressed in percentage (%). It is representative of the elasticity of the yarn. The higher the average elongation at break of the yarn, the more elastic the yarn. The average elongation at break was measured in accordance with the method described in DIN ISO 13895.

[0132] All tests were carried out under ambient conditions standardized by DIN EN ISO 139 (relative humidity (RH) being 65% ± 2%, temperature being 20°C ± 2°C).

[0133] [Fig. 3a], [Fig. 3b], [Fig. 3c] and [Fig. 3d] are graphs showing the tensile force versus elongation curves for the yarns of Tests 1, 2, 3 and 4 respectively.

[0134] The results are collected in Table 2 below: [Table 2]

[0135] Table 2: Mechanical properties

[0136] These results show that the process according to the invention makes it possible to produce a yarn based on a recyclable polyamide block and polyether block copolymer having an average elongation at break greater than 200%, in particular 233.3%. Thus, the yarn from Test 1 is capable of being stretched over a length representing 233.3% of its initial length without breaking. This produces a yarn with very good elasticity, usable in elastic textiles such as sports tights, swimsuits, etc.

[0137] Furthermore, given its chemical nature based on polyamide and polyether, such an elastic yarn can be combined with other non-elastic yarns, based on polyamide (for example polyamide PA 6 or PA66) or polyester, to produce elastic textiles. The elastic textile thus obtained is completely recyclable. It is therefore not necessary to incinerate the elastic textiles thus obtained or to bury them.

[0138] The results in Table 2 above also show that at the same fineness, the higher the preliminary cold drawing ratio (D1), the more elastic the wire: thus, Test 1, for which the cold drawing ratio D1 is 5.07, has a particularly high average elongation at break (233.3%), while Test 3, for which the preliminary cold drawing ratio is 2.53, has a lower average elongation at break (106%).

[0139] It is thus preferred that the preliminary cold drawing ratio D1 be greater than or equal to 2.53.

[0140] The results in Table 2 above also show that at the same fineness and the same preliminary cold drawing rate, the higher the cold drawing rate (D3) after passing through the furnace, the more elastic the wire is: thus, Test 4, for which the cold drawing rate (D3) after passing through the furnace is 1.51, has a particularly high average elongation at break (180%), while Test 3, for which the cold drawing rate (D3) after passing through the furnace is 1, has a lower average elongation at break (106%).

[0141] It is therefore preferred that the cold drawing rate (D3) after passing through the furnace is greater than or equal to 1.

[0142] In all cases, it is also observed that the lower the hot drawing ratio (D2), the more elastic the yarn. Thus, it is preferred that the hot drawing ratio (D2) be less than or equal to 8. c) Evaluation of viscoelastic properties:

[0143] For each Test 1-4, the following viscoelastic properties of the yarn obtained after winding on winding roller 8 were measured:

[0144] Elastic return: elastic return is expressed as a percentage (%). It represents the recovery power of the elastic thread when the constraints applied to deform it are removed. The aim is to obtain the highest possible elastic return. Elastic return was measured in accordance with the method described in DIN 53835-2;

[0145] Permanent deformation: permanent or irreversible deformation is expressed as a percentage (%). It represents the permanent loss of elasticity of the wire after several successive stretches. The aim is to obtain the lowest possible permanent deformation. Permanent deformation was measured in accordance with the method described in DIN 53835-2.

[0146] All tests were carried out under ambient conditions standardized by DIN EN ISO 139 (relative humidity (RH) being 65% ± 2%, temperature being 20°C ± 2°C).

[0147] [Fig. 4a], [Fig. 4b], [Fig. 4c] and [Fig. 4d] are graphs showing the hysteresis curves obtained respectively for the wires of Tests 1, 2, 3 and 4. From these curves, it is possible to calculate the elastic return and the permanent deformation of the wires of Tests 1-4.

[0148] The results are shown in the graph shown in Figure 2. This graph shows that the process according to the invention makes it possible to produce a yarn, for example a monofilament yarn, based on a recyclable polyamide block and polyether block copolymer with remarkable viscoelastic properties. Thus, Test 1 has an elastic return of 96.6% and a permanent deformation of only 2.5%. The process according to the invention thus makes it possible to produce recyclable elastic yarns with elastic properties comparable to existing elastic yarns which are not recyclable.

[0149] EXAMPLE 2

[0150] A wire 21 was obtained according to the method according to the invention described in Figure 5.

[0151] The parameter values ​​were as follows:

[0152] The linear speed VP was 65.4 m / min

[0153] The linear speed V1 of the delivery roller 6a was 1333 m / min

[0154] The linear speed V2 of the stretching rollers 26a heated to 50°C was 1333 m / min

[0155] The linear speed V3 of roller 28a at room temperature was 2000 m / min

[0156] The linear speed of the winding roller is 1950 m / min

[0157] The stretch ratio D1 was: D1 = VP / V1 = 20.4

[0158] The stretch ratio D2 was: D2 = V2 / V1 = 1

[0159] The stretch ratio D3 was: D3 = V3 / V2 = 1.5

[0160] Yarn 21 has a linear density of 193 dtex (174 D) with 34 filaments.

[0161] The mechanical properties of wire 21 were measured according to the methods described in Example 1.

[0162] [Fig. 6] is a graph showing the tensile force versus elongation curve for wire 21.

[0163] The results are collected in the following Table 3:

[0164] [Table 3]

[0165] Table 3: Mechanical properties

[0166] The viscoelastic properties of yarn 21 were measured according to the methods described in Example 1.

[0167] [Fig. 7] is a graph showing the hysteresis curve obtained for wire 21.

[0168] The results are collected in the following Table 4:

[0169] [Table 4]

[0170] Table 4: Viscoelastic properties

[0171] It is clear from this example that the method according to the invention makes it possible to produce a yarn, for example a multifilament yarn, based on a recyclable polyamide block and polyether block copolymer having remarkable viscoelastic properties. The method according to the invention thus makes it possible to produce recyclable elastic yarns having elastic properties comparable to existing elastic yarns which are not recyclable.

[0172] EXAMPLE 3

[0173] A multifilament yarn 21 obtained according to the method described in Figure 5 was subjected to a post-stretching step then a relaxation step as described in Figure 8, with the following parameters:

[0174] - Initial average fineness of the multifilament yarn in denier, on the winding roll 8: 202

[0175] - Linear speed V4 of the first post-stretching roller 30a: 103 m / min

[0176] - Linear speed V5 of the second post-stretching roller 31a: 107 m / min

[0177] - D4 post-stretching rate: D4 = V5 / V4 = 1.65

[0178] - Linear speed V6 of the final winding roller 32: 107 m / min

[0179] - D5 relaxation rate: D5 = V6 / V5 = 0.63 The overall post-stretching rate over the two stages was therefore: D4 x D5 = 1.04.

[0180] The final average yarn fineness after the post-drafting and relaxation steps, on the final winding roll 32, was, in denier: 194.

[0181] [Fig. 9a] is a graph showing the tensile force versus elongation curve for multifilament yarn 21 before the post-stretching and relaxation steps.

[0182] [Fig. 9b] is a graph showing the tensile force versus elongation curve for multifilament yarn 21 after the post-stretching and relaxation steps.

[0183] The standards used to perform these tests are the same as those in the previous examples.

[0184] On these curves:

[0185] - the part referenced A corresponds to the initial elastic part,

[0186] - the part referenced B corresponds to the rigid part,

[0187] - the part referenced C corresponds to the viscoelastic part.

[0188] The results are collected in the following Table 5:

[0189] [Table 5]

[0190] These results show that the yarn exhibits superior elastic properties after undergoing post-stretching and relaxation.

[0191] EXAMPLE 4:

[0192] A textile comprising elastic threads (20, 21, 22) according to the invention obtained according to the methods described in Figures 1, 5 and 8 and polyamide 6 (PA 6) threads was recycled as described below. 1°) Preparation of the particles and mixtures of the particles:

[0193] Elastic threads and polyamide 6 threads were ground to obtain particles.

[0194] Hereinafter referred to as:

[0195] Particles 1: Polyamide 6 yarn particles, Particles 2: Elastic yarn particles.

[0196] The following three blends were made

[0197] Mixture 1: this mixture included, in mass relative to the mass of the mixture:

[0198] - 90% of Particles 1, and

[0199] - 10% of Particles 2.

[0200] Mixture 2: this mixture included, in mass relative to the mass of the mixture:

[0201] - 80% of Particles 1, and

[0202] - 20% of Particles 2.

[0203] Mixture 3: this mixture included, in mass relative to the mass of the mixture:

[0204] - 70% of Particles 1,

[0205] - 30% of Particles 2.

[0206] These blends were extruded using a six-zone screw extruder. The extrusion parameters used are listed in Table 6 below:

[0207] [Table 6]

[0208]

[0209] At the extruder outlet, the molten mixtures are subjected to granulation. Hereinafter called:

[0210] Granules 1: the granules resulting from the extrusion of Mix 1

[0211] Granules 2: the granules resulting from the extrusion of Mix 2

[0212] Granules 3: granules resulting from the extrusion of Mix 3

[0213] 2°) Characterization

[0214] Particles 1, Particles 2, and Granules 1, Granules 2 and Granules 3 were characterized using the following tests:

[0215] Differential Scanning Calorimetry (DSC)

[0216] Thermal Gravimetric Analysis (TGA)

[0217] Viscosity index measurement a°) Differential scanning calorimetry DSC

[0218] This test is used to check whether the pellet will be one phase or two phases. The test was carried out according to the following program:

[0219] First DSC cycle: from -70°C to +350°C or less if thermal degradation begins before, no holding time,

[0220] Second DSC cycle: from + 350°C to - 70°C, no holding time,

[0221] Third DSC cycle: from -70°C to +350°C or less if thermal degradation begins before,

[0222] Final cooling

[0223] The measurement was made after the first cycle for Particles 1 and for Particles 2.

[0224] The measurement was made after the second cycle for Granules 1, Granules 2 and Granules 3. The glass transition temperature is determined from the second cycle. The melting point is determined from the first cycle. The crystallization temperature is determined from the first cooling cycle.

[0225] The results are collected in the following Table 7:

[0226] [Table 7]

[0227] These results show that Granules 1, Granules 2 and Granules 3 are homogeneous mixtures. b°) Thermal gravimetric analysis

[0228] This test allows us to check the start of thermal degradation for each particle / granule. The test was carried out according to the following program:

[0229] Nitrogen condition

[0230] Heating up to 600°C

[0231] Heating speed always at 10°C / min

[0232] The results are collected in the following Table 8: [Table 8]

[0233] These results show that Particles 1, Particles 2 and the extruded blends Granules 1, Granules 2 and Granules 3 begin to thermally degrade at temperatures above their respective spinning temperatures. Indeed:

[0234] Spinning temperature for Particles 1: 260°C

[0235] Spinning temperature for Particles 2: 210°C

[0236] Spinning temperature for Pellets 1, Pellets 2 and Pellets 3: 250°C

[0237] These results confirm that the conditions for spinning the extruded mixtures Granules 1, Granules 2 and Granules 3 are met. c°) Measurement of the viscosity index

[0238] This test is used to check whether the viscosity of each extruded mixture Granules 1, Granules 2 and Granules 3 is suitable for melt spinning or not. The test was carried out using sulfuric acid H2SO4 (0.5%).

[0239] The results are collected in the following Table 9:

[0240] [Table 9]

[0241] These results confirm that the extruded mixtures Granules 1, Granules 2 and Granules 3 have good viscosity, suitable for melt spinning. 3°) Production of recycled yarn from the extruded mixture Granules 2

[0242] The Granules 2 mixture is left to dry at 65°C under vacuum overnight.

[0243] A spinning machine is prepared, comprising an extruder, a spinning metering pump, and a spinning pack including a spinneret. The extruder is purged, and then the spinning pack is inserted.

[0244] The extruder is fed with Pellets 2 and extrusion is started. It was observed that stable extrusion and then stable spinning were achieved. This allowed the spinning of a recycled multifilament yarn with a fineness of approximately 480 dtex.

[0245] The recycled multifilament yarn thus obtained can be used to make new textiles.

Claims

CLAIMS 1. Method for manufacturing an elastic yarn (20; 21) by melt spinning using a spinning machine (1) comprising an extruder (2), a spinning metering pump (17), a spinning pack (3) comprising at least one die (19), a cooling system (4, 5; 22), at least one delivery roller (6a) and at least one stretching roller (7a; 26a), said method comprising at least the following steps: A) said extruder (2) is fed with granules (10) of a copolymer with polyamide blocks and polyether blocks, the polyamide blocks being chosen from PA 11, PA 12, PA 1010, PA 1014, their copolymer and their mixture, the polyether blocks being blocks derived from polytetramethylene glycol, the hardness of the copolymer measured according to standard 7619-1 being between 22 and 61 ShD, in order to obtain by extrusion a molten elastomer of the copolymer with polyamide blocks and polyether blocks, B) the molten elastomer obtained in step A) is spun within the die (19) of said spinning pack (3) in order to obtain a yarn (20; 21) of the copolymer with polyamide blocks and polyether blocks, C) the yarn (20; 21) of the copolymer with polyamide blocks and polyether blocks obtained in step B) is subjected at the outlet of the die (19) to cooling to a temperature strictly lower than the glass transition temperature of said polyamide blocks, for example to a temperature ranging from approximately 10°C to approximately 49°C, preferably ranging from approximately 10°C to approximately 30°C, more preferably ranging from approximately 20°C to approximately 25°C, D) the yarn (20; 21) of the polyamide block and polyether block copolymer is subjected to preliminary stretching at the temperature of step C), E) the yarn (20; 21) of the copolymer with polyamide blocks and polyether blocks obtained at the end of step D) is subjected to hot drawing at a temperature strictly higher than the glass transition temperature of said polyamide blocks, for example at a temperature ranging from approximately 45°C to approximately 125°C, preferably ranging from 45°C to 120°C, preferably ranging from approximately 50°C to approximately 125°C, more preferably ranging from approximately 90°C to approximately 120°C, F) the yarn (20; 21) of the polyamide block and polyether block copolymer obtained at the end of step E) is subjected to cold drawing at a temperature ranging from approximately 10°C to approximately 49°C, ranging from approximately 10°C to approximately 30°C, preferably ranging from approximately 20°C to approximately 25°C.

2. Method according to claim 1, characterized in that, said yarn (20; 21) leaving the spinneret (19) spinning pack (3) of step B) according to a linear speed of the spinning metering pump VP, the yarn (20; 21) is drawn in step D) by passing over a delivery roller (6a) having a linear delivery speed V1, V1 being chosen such that the rate D1 of the preliminary drawing is greater than or equal to 2.53, where D1 = V1 / VP.

3. Method according to claim 1 or 2, characterized in that during step E), the wire (20; 21) is stretched by passing over a first stretching roller (7a; 26a) having a linear stretching speed V2, V2 being chosen such that the rate D2 of the hot stretching is less than or equal to 8, where D2 = V2 / V1.

4. Method according to any one of claims 1 to 3, characterized in that during step F), the wire (20; 21) is drawn by passing it over a second drawing roller (8; 28a) having a linear drawing speed V3, V3 being chosen such that the cold drawing rate D3 is greater than or equal to 1, where D3 = V3 / V2.

5. Method according to claim 4, characterized in that the second stretching roller is a winding roller (8).

6. Method according to any one of the preceding claims, characterized in that during step C), the wire (20) is cooled by quenching with water (5).

7. Method according to any one of claims 1 to 5, characterized in that during step C), the wire (21) is cooled by air.

8. Method according to any one of the preceding claims, characterized in that the thread (20) of the copolymer with polyamide blocks and polyether blocks obtained at the end of step F) is heat-set at a temperature strictly higher than the glass transition temperature of said polyamide blocks, for example at a temperature ranging from approximately 70°C to approximately 90°C, preferably approximately 80°C.

9. Method according to any one of claims 1 to 7, characterized in that it further comprises the following step G): - G) the yarn (20; 21) of the copolymer with polyamide blocks and polyether blocks obtained at the end of step F) is subjected to post-stretching at a temperature strictly lower than the glass transition temperature of said polyamide blocks, for example at a temperature ranging from approximately 10°C to approximately 30°C, preferably ranging from approximately 20°C to approximately 25°C.

10. Method according to claim 9, characterized in that during step G), said wire (20, 21) is post-stretched by passing over a first post-stretching roller having a linear speed V4 then over a second post-stretching roller having a linear speed V5, V4 and V5 being chosen such that the post-stretching rate D4 is greater than or equal to 1.65, where D4 = V5 / V4.

11. Method according to claim 9 or 10, characterized in that it further comprises the following step H): H) the yarn (20; 21) of the copolymer with polyamide blocks and polyether blocks obtained at the end of step G) is subjected to relaxation at a temperature strictly lower than the glass transition temperature of said polyamide blocks, for example at a temperature ranging from approximately 10°C to approximately 30°C, preferably ranging from approximately 20°C to approximately 25°C.

12. Method according to claim 11, characterized in that during step H), said wire (20; 21) is relaxed by passing over a winding roller having a linear speed V6 chosen such that V6 / V4 ranges from 1 to 1.50, preferably from 1 to 1.25, more preferably from 1.00 to 1.

05.

13. Method according to any one of claims 2 to 12, characterized in that D1 = 5.

07.

14. Method according to claims 3 and 13, characterized in that D2 = 4.

15. Method according to claims 4 and 14, characterized in that D3 = 1.

16. Method according to any one of the preceding claims, characterized in that the hardness of the copolymer measured according to standard 7619-1 is between 22 and 55 ShD, preferably between 22 and 40 ShD.

17. Method according to any one of the preceding claims, characterized in that the polyamide blocks are chosen from PA 11, PA 12, their copolymer and their mixture.

18. Method according to claim 17, characterized in that the polyamide blocks are PA 11 blocks.

19. Elastic thread (20; 21) obtainable by the method according to any one of claims 1 to 18, having an average elongation at break, measured according to standard DIN ISO 13895, greater than or equal to approximately 106%, preferably greater than or equal to approximately 131%, preferably greater than or equal to 164.5%, preferably greater than or equal to 180%, for example approximately 233.3%, and / or having an elastic return, measured according to standard DIN 53835-2, greater than or equal to approximately 86.5%, preferably greater than or equal to 91.8%, preferably greater than or equal to 94%, preferably greater than or equal to 96.3%, for example approximately 96.6%.

20. Textile comprising at least one yarn (20; 21) obtainable according to any one of claims 1 to 18 or a yarn according to claim 19.

21. Garment comprising at least one thread (20; 21) obtainable according to any one of claims 1 to 18 or a thread according to claim 19.

22. Installation (100; 200) configured to implement the method according to any one of claims 1 to 18, said installation comprising: - a spinning machine (1) comprising an extruder (2), a spinning metering pump (17), a spinning pack (3) comprising at least one die (19), - a cooling system (4, 5; 22) arranged at the outlet of the die (19), - at least one delivery roller (6a) arranged at the outlet of the cooling system (4, 5; 22), - at least one first stretching roller (7a; 26a), arranged downstream of the delivery roller (6a), - at least one second stretching roller (8; 28a), arranged downstream of the first stretching roller (7a; 26a), - a heating means (9; 26) arranged between the delivery roller (6a) and the first stretching roller (7a; 26a).

23. Installation (100) according to claim 22, characterized in that the second stretching roller (8) is a winding roller.

24. Installation according to claim 23, characterized in that it further comprises: at least one first post-stretching roller (30a) arranged downstream of the winding roller (8), at least one second post-stretching roller (31a) arranged downstream of the first post-stretching roller (30a).

25. Method for recycling a textile comprising at least one elastic thread (20; 21; 22) according to claim 19 or obtainable according to any one of claims 1 to 18, and at least one thermoplastic thread, preferably made of polyamide, characterized in that it comprises the following steps: - i) said textile is ground to obtain particles, - ii) the particles from step i) are then melted in an extruder in order to obtain granules of said mixture.

26. Recycling method according to claim 25, characterized in that it further comprises the following step iii): - iii) a recycled yarn is spun by melt extrusion from the pellets obtained in step ii).

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