Method to increase the elastic properties of thread

Abstract

The present invention relates to a method for increasing the elastic properties of a yarn obtained by a melt spinning process, comprising the step of: Step 1) relaxing the yarn at a temperature in the range of about 70°C to about 110°C.

Description

Technology Field

[0001] The present invention relates to a method for increasing the elastic properties of recyclable yarn, wherein the yarn has initial elasticity. The yarn obtained by the method according to the present invention can be used particularly in the manufacture of textiles and footwear. Background Technology

[0002] Elastic fabrics have long been known. Such fabrics can be used in the manufacture of footwear as well as clothing, such as sports tights, socks, and swimwear, for example in the sports field. The elasticity of these fabrics is generally obtained through elastane yarns, which may be present in the fabric in a content ranging from 2% to 50% of the total composition of the yarns and / or fibers, for example. Elastane is a segmented polyurethane in the form of a copolymer of soft and hard segments. Elastane yarns possess a high level of stretch or extension: these yarns can be stretched, for example, to more than 600% of their original length before breaking. Elastane yarns also possess high recovery power, i.e., elastic return: thus, after being stretched multiple times, these yarns recover to a length very close to their original length when the stretching stress is released, for example, to a length ranging from 90% to 100% of their original length.

[0003] However, the production and use of elastane threads have several disadvantages.

[0004] According to ADEME (French Agency for Environment and Energy), the production of 1 kg of elastane yarn generates 21 kg of CO2 equivalent (ADEME Basic Impact V2.01). Therefore, the production of elastane yarn has a relatively large negative impact on the environment.

[0005] Furthermore, since elastane is a thermosetting material, it decomposes before melting. Therefore, thermal recycling of elastane is impossible. While chemical recycling of elastane could be considered, the necessity of solvents in such methods makes it unlikely to be feasible due to the excessive environmental impact.

[0006] Therefore, to date in Europe, fabrics containing elastane are generally incinerated or landfilled. These methods have serious adverse effects on the environment. Thus, according to ADEME, 1 kg of incinerated fabric emits 0.4 kg of CO2 equivalent, and 1 kg of landfilled fabric emits 2.2 kg of CO2 equivalent (ADEME Basic Impact V2.01).

[0007] Therefore, in terms of current environmental considerations, there is still a need for recyclable elastic fabrics. In this context, there is a continued need for recyclable elastic yarns that possess elastic properties similar to, or even superior to, existing non-recyclable elastic yarns such as elastane yarns. Furthermore, it should be possible to produce fully recyclable elastic fabrics by combining these recyclable elastic yarns with recyclable non-elastic yarns, regardless of the proportion of elastic yarns within the fabric.

[0008] The present invention aims to address this need by proposing a method to increase the elastic properties of recyclable yarns obtained by a melt extrusion process.

[0009] The present invention relates to a method for increasing the elastic properties of a yarn obtained by a melt spinning process, wherein the method

[0010] - A) A step of feeding thermoplastic copolymer pellets into an extruder to obtain a molten elastomer of the copolymer by extrusion - the hardness of the copolymer is in the range of 10 to 61 ShD when measured according to Standard 7619-1 -,

[0011] - B) A step of obtaining copolymer threads by spinning the molten elastomer obtained in step A) into the spinneret of a spinning pack,

[0012] - C) a step of cooling the copolymer yarn obtained in step B) at the spinneret exit to a temperature in the range of about 10°C to about 40°C, preferably about 20°C to about 25°C,

[0013] - D) A step of pre-stretching the yarn obtained in step C) at the temperature of step C),

[0014] - E) a step of hot stretching the yarn obtained in step D) at a temperature in the range of about 40°C to about 125°C, preferably about 45°C to about 90°C,

[0015] - F) a step of cold stretching the yarn obtained in step E) at a temperature in the range of about 10°C to about 40°C, preferably about 20°C to about 25°C,

[0016] - G) Optionally, a step of relaxing the yarn obtained in step F) at a temperature in the range of about 10°C to about 40°C, preferably about 20°C to about 25°C,

[0017] - H) Optionally, at least one post-stretching step of hot-stretching the yarn obtained in step F) or step G) at a temperature, for example, in the range of 30°C to 70°C, followed by cold-stretching at a temperature, for example, in the range of 20°C to 25°C,

[0018] - I) Optionally, a step of winding the yarn obtained from one of steps F), G), or H) onto an initial storage winder without stretching and without relaxation.

[0019] Includes,

[0020] The above method is characterized by including step 1) of relaxing the thread obtained in any one of steps F) to I) at a temperature in the range of about 40°C to about 110°C.

[0021] As can be seen from the detailed description and examples below, the method according to the present invention can improve the elastic properties of a yarn manufactured according to at least steps A) to F) above. In particular, the method according to the present invention can increase the strain at break of such yarn.

[0022] The method according to the present invention can also improve the extensibility (greater elongation at break) of a fabric comprising yarns manufactured according to at least steps A) through F) above. In particular, the method according to the present invention can improve the elastic modulus (i.e., force) required to stretch or relax such a fabric. The method according to the present invention can improve the elastic level of such a fabric in all directions (e.g., in the case of a knit, in the warp direction, weft direction, and diagonal direction). Additionally, the method according to the present invention enables the fabric to be imparted with greater retention.

[0023] In one embodiment, the thermoplastic copolymer is a copolymer having a polyamide block and a polyether block, the polyamide block is selected from PA 11, PA 12, PA 1010, PA 1014, copolymers thereof and mixtures thereof, the polyether block is a block derived from polytetramethylene glycol, and the hardness of the copolymer is 22 to 61 ShD, preferably 22 to 55 ShD, more preferably 22 to 40 ShD when measured according to standard 7619-1. Preferably, the polyamide block is selected from PA 11, PA 12, copolymers thereof and mixtures thereof. More preferably, the polyamide block is a PA 11 block.

[0024] In another embodiment, the thermoplastic copolymer is selected from thermoplastic elastomers (TPE), thermoplastic polyurethane elastomers, thermoplastic polyolefin elastomers (POE), polyphthalamide (PPA), polyether-esteramide elastomers, thermoplastic copolyester elastomers, copolyester (ether) elastomers, and mixtures thereof, and the hardness of the copolymer is 10 to 57 ShD, preferably 10 to 45 ShD, more preferably 10 to 35 ShD, more preferably about 22 ShD when measured according to standard 7619-1. Preferably, the copolymer is selected from a copolymer comprising a flexible block and a rigid block, the flexible block is a polyether block derived from polytetramethylene glycol (PTMEG), and the rigid block is selected from a diisocyanate block and a polyester block. Advantageously, the copolymer is selected from copolymers in which the flexible block is a polyether block derived from polytetramethylene glycol and the rigid block is a polyester block. For example, a copolymer having a polyether block and a polyester block is a compound of the following formula (I):

[0025]

[0026] In chemical formula (I), y=0.3x.

[0027] In one embodiment, step 1 of the method according to the present invention is performed at a temperature in the range of about 80°C to about 100°C, preferably about 90°C to about 100°C.

[0028] In one embodiment of the method according to the present invention, the thread obtained at the end of steps A) to F) and H) is treated with hot air at 70°C.

[0029] In one embodiment of the method according to the present invention, the thread obtained at the end of steps A) to F) and H) is treated with hot air at 100°C.

[0030] In one embodiment of the method according to the present invention, during step 1°), the yarn obtained in step F) is passed over a first roll having a linear speed W1 and then over a second roll having a linear speed W2, wherein the linear speed W2 is strictly lower than the linear speed W1. In this embodiment, for example, the first roll may be heated to a temperature in the range of about 40°C to 125°C, preferably 40°C to 90°C, more preferably 45°C to 70°C.

[0031] In another embodiment of the method according to the present invention, step 1°) is the following step:

[0032] - 1°)a1), step F) i) winding the yarn obtained in step F) onto a perforated winding roll - the applied winding tension is selected to enable the yarn to contract as it is wound onto the winding roll -, then

[0033] - 1°)a2), step of placing the coiled thread roll into a steam chamber or boiling water bath

[0034] Includes

[0035] In another embodiment of the method according to the present invention, during step 1), the yarn obtained in step I) is unwound from an initial storage winder at a first linear speed W3, and after passing through a heating medium, is wound onto a final storage winder at a linear speed W4, wherein the linear speed W4 is strictly lower than the linear speed W3.

[0036] In another embodiment of the method according to the present invention, the yarn obtained in one of steps F) to I) is present in a fabric, and step 1) comprises treating the fabric at a temperature in the range of about 70°C to about 110°C. For example, the fabric is treated as follows:

[0037] - purifying,

[0038] - stripping

[0039] - dyeing

[0040] You can receive one or more of them.

[0041] The method according to the present invention is intended to be applied to a yarn obtained by a melt spinning process comprising steps A) through F) above and optionally steps G) through I) above. For example, these steps are performed through a spinning machine comprising an extruder, a spinning metering pump, a spinning pack comprising at least one spinneret, a cooling system, at least one transfer roll, and at least one draft roll.

[0042] In this application, "thread" refers to any fiber of infinite length. In particular, the thread may be in the form of a monofilament or a multifilament.

[0043] In this application, the glass transition temperature refers to a temperature below which the polymer is in a glass (solid) state and above which the polymer is in a rubber state (plastic solid behavior).

[0044] In this application, "fabric" means any material made of fibers or yarn. In particular, fabric may be an arrangement of fibers and / or yarn in the form of knit, woven, nonwoven, braid, and combinations thereof.

[0045] A method for manufacturing a yarn to be used in the method according to the present invention is based on melt spinning technology that uses extrusion-spinning of a molten polymer within an extruder and a spinning pack. Once extruded, the yarn undergoes a series of stretchings that may be cold or hot. In particular, the extruded yarn undergoes at least one preliminary cold stretching, at least one hot stretching, and at least one cold stretching following the hot stretching. Each of these stretchings, namely the preliminary cold stretching, the hot stretching, and the cold stretching after the hot stretching, may ultimately consist of several partial stretchings.

[0046] In this application, "upstream" means the direction toward the point where the yarn (spun pack) is "generated" or extruded, and "downstream" means the opposite direction, that is, the direction toward the point where the elastic yarn is stored after the yarn has undergone all the desired stretching.

[0047] Accordingly, in the first step of the present method, thermoplastic copolymer pellets are fed into an extruder. Through this step, a molten elastomer of the copolymer can be obtained by extrusion.

[0048] In one embodiment, the thermoplastic copolymer is a copolymer having a polyamide block and a polyether block, the polyamide block is selected from PA 11, PA 12, PA 1010, PA 1014, copolymers thereof and mixtures thereof, the polyether block is a block derived from polytetramethylene glycol, and the hardness of the copolymer is 22 to 61 ShD, preferably 22 to 55 ShD, more preferably 22 to 40 ShD when measured according to standard 7619-1. Preferably, the polyamide block is selected from PA 11, PA 12, copolymers thereof and mixtures thereof. More preferably, the polyamide block is a PA 11 block.

[0049] The nomenclature used to define polyamides is described in the ISO 1874-1:2011 standard "Plastics - Polyamide (PA) materials for moulding and extrusion - Part 1: Designation", particularly on page 3 (Tables 1 and 2), and is well known to those skilled in the art.

[0050] Furthermore, the expressions “…to…” and “…from…” used in this description should be understood to include the respective limits mentioned.

[0051] The word "polyamide" includes both homopolyamide and copolyamide.

[0052] The copolymer that can be used to manufacture the thread to be used in the method according to the present invention is a product sold by Arkema under the trade name "PEBAX® RNEW 35R53 SP 01". This elastomer copolymer has the following characteristics:

[0053] - Density of 1020 kg / m³ when measured according to ISO 1183 standard 3 ,

[0054] - 25 Shore D hardness at 15 seconds when measured according to ISO 7619-1 standard,

[0055] - Melting point 135℃ when measured according to ISO 11357-1 / -3 standard,

[0056] - Content of bio-derived components, such as PA 11 polyamide, is 29% when measured according to ASTM D6866 standard.

[0057] Another copolymer that can be used to manufacture the thread used in the method according to the present invention is a product sold by Arkema under the trade name "PEBAX® 7033 SP 01". This elastomer copolymer has the following characteristics:

[0058] - Density 1010 kg / m³ when measured according to ISO 1183 standard 3 ,

[0059] - 61 Shore D hardness at 15 seconds when measured according to ISO 7619-1 standard,

[0060] - Melting point 172℃ when measured according to ISO 11357-1 / -3 standard.

[0061] Another copolymer that can be used to manufacture the thread used in the method according to the present invention is a product sold by Arkema under the trade name "PEBAX® 2533 SA 01". This elastomeric copolymer has the following characteristics:

[0062] - Density of 1,000 kg / m³ when measured according to ISO 1183 standard 3 ,

[0063] - 22 Shore D hardness at 15 seconds when measured according to ISO 7619-1 standard,

[0064] - Melting point 134℃ when measured according to ISO 11357-1 / -3 standard.

[0065] In another embodiment, the thermoplastic copolymer is selected from thermoplastic elastomers (TPE), thermoplastic polyurethane elastomers, thermoplastic polyolefin elastomers (POE), polyphthalamide (PPA), polyether-esteramide elastomers, thermoplastic copolyester elastomers, copolyester (ether) elastomers, and mixtures thereof, and the hardness of the copolymer is 10 to 57 ShD, preferably 10 to 45 ShD, more preferably 10 to 35 ShD, and more preferably about 22 ShD when measured according to standard 7619-1. Such hardness makes it possible to obtain a yarn having excellent elastic properties.

[0066] Among thermoplastic polyurethane (TPU) elastomers, the following types may be mentioned: (TPU-polyester), (TPU-polyether), (TPU-polycarbonate), (TPU-polycaprolactone), and (TPU-ester / ether). Among thermoplastic copolyester elastomers, the following types may be mentioned: TPC-ET elastomer, TPC-ES elastomer, and TPC elastomer.

[0067] The elastomer is a copolymer composed of a series of rigid polymer blocks (hereinafter referred to as rigid blocks) and flexible polymer blocks (hereinafter referred to as flexible blocks). The rigid blocks may be selected from, for example, polyester blocks and diisocyanate blocks. The flexible blocks may be, for example, polyol blocks. The polyols may be based on polyesters, polyether-esters, polycarbonates, or polyethers.

[0068] Accordingly, preferably, the copolymer is selected from a copolymer comprising a flexible block and a hard block, wherein the flexible block is a polyether block derived from polytetramethylene glycol (PTMEG), and the hard block is selected from a diisocyanate block and a polyester block.

[0069] More preferably, the copolymer is selected from copolymers in which the flexible block is a polyether block derived from polytetramethylene glycol and the hard block is a polyester block.

[0070] A copolymer having a polyether block and a polyester block that can be used in the manufacture of a yarn to be used in the method according to the present invention is a compound of the following formula (I):

[0071]

[0072] In chemical formula (I), y=0.3x.

[0073] In this chemical formula (I), the soft block is a polyether block which is itself a poly(tetramethylene ether) glycol (hereinafter PTMEG) block with a degree of polymerization DP of 27 ± 2 and a molecular weight of 1950 ± 150 g / mol, and the hard block is based on a polyester which is itself a polybutylene terephthalate (hereinafter PBT) block with a molecular weight of about 875 ± 100 g / mol.

[0074] Therefore, the structure of the copolymer of formula (I) can be presented as follows:

[0075]

[0076] A copolymer that can be used to manufacture the yarn used in the method according to the present invention may have a melting point in the range of, for example, about 150°C to about 222°C. The melting point of the copolymer will be selected according to the desired application of the obtained elastic yarn.

[0077] The copolymer that can be used to manufacture the yarn to be used in the method according to the present invention is a product sold by Radici Group under the trade name "HERAFLEX E 2517 1000 NT". This elastomeric copolymer is a copolymer having a polyester block and a polyether block of the above chemical formula (I) and has the following characteristics:

[0078] - Density of 1080 kg / m³ when measured according to ISO 1183 standard 3 ,

[0079] - 22 Shore D hardness at 15 seconds when measured according to ISO 7619-1 standard,

[0080] - Melting point 175℃ when measured according to ISO 11357-1 / -3 standard,

[0081] - When measured according to the ISO 1133 standard, the melt flow rate index is 12 g / 10 min.

[0082] To proceed with Step A), the copolymer may be pre-dried to reduce the moisture content of the copolymer to less than 200 ppm. A moisture content characteristic test may be performed, for example, using the Karl-Fischer titration method.

[0083] The spinneret may include an extruder, such as a screw extruder, a spinning metering pump, and a spinning pack. The spinning pack generally includes a spinneret. The spinning pack may also generally include a distribution plate, a metal filter, and filter sand. The extruder and the spinning pump are purged before receiving the copolymer. The spinneret also includes a cooling system, at least one transfer roll, e.g., a pair of transfer rolls, and at least one draft roll, e.g., a pair of draft rolls. The draft roll may or may not be heated. The spinneret also preferably includes a winding roll for storing the produced yarn.

[0084] According to Step A), thermoplastic copolymer pellets, which are elastomers, are fed into an extruder and melted. At the extruder outlet, molten elastomer of the copolymer is obtained. According to Step B, the second step, the molten elastomer obtained in Step A) is spun within the spinneret of a spinning pack to obtain copolymer threads. A spinning metering pump controls the flow rate of the elastomer toward the spinneret of the spinning pack. Impurities can be removed using a metal filter and filter sand. The elastomer is injected into the spinneret. At the spinneret outlet, copolymer threads are formed.

[0085] According to step C), which is the third step, the copolymer yarn is cooled at the spinneret exit to a temperature in the range of about 10°C to about 40°C, preferably about 20°C to about 25°C.

[0086] Preferably, when the copolymer is a copolymer having a soft block and a hard block, the cooling of the copolymer is performed at a temperature strictly lower than the glass transition temperature of the hard block.

[0087] Cooling of the yarn can be performed by air quenching or water quenching depending on the thickness of each filament of the yarn and the efficiency of the cooling system. In the case of water quenching, the yarn can be passed through a tank filled with water at, for example, 20°C to 25°C.

[0088] In the case of air cooling, the thread can be passed through a cold air flow controlled to a temperature in the range of, for example, 10°C to 25°C.

[0089] During the cooling phase, the thread solidifies.

[0090] In the fourth step, step D), the yarn undergoes primary stretching or preliminary stretching at the temperature of step C). Through this cooling preliminary stretching, primary elasticity can be imparted to the yarn.

[0091] For example, when the yarn exiting the spinneret of the spinning pack in step B) is at a linear spinning metering pump speed VP, the yarn may be stretched while passing through a transfer roll having a transfer linear speed V1 in step D), V1 is selected such that the pre-elongation D1 is 2 or more, preferably 8 or more, for example 12 or more, and D1 = V1 / VP. The elongation D1 may have a value greater than, for example 100, for example 132. Such a pre-elongation of 2 or more can impart significant elasticity to the yarn while possessing excellent tensile strength (tenacity), and thus excellent mechanical properties.

[0092] In this application, the term "linear velocity" of a pump or a conveying, stretching, or winding roll refers to the linear velocity of the outer wall of the pump or roll in contact with the yarn during the displacement of the yarn.

[0093] The yarn obtained at the end of step D) can be stored in a winding roll before receiving step E).

[0094] According to Step E), which is Step 5, the copolymer yarn obtained in Step D) is hot-stretched at a temperature ranging from about 40°C to about 125°C, preferably from about 45°C to about 90°C, whether stored in a winding roll or fed directly from a feed roll. Preferably, if the copolymer is a copolymer having a flexible block and a hard block, the hot-stretching is performed at a temperature strictly higher than the glass transition temperature of the hard block.

[0095] To perform such hot drawing, the yarn passes through or comes into contact with a heating means heated to a desired temperature. For example, the heating means may be an oven heated to a desired temperature. Alternatively, or in combination, the heating means may include one or more draft rolls heated to a desired temperature. Through hot drawing, the thickness of the yarn can be reduced, that is to say, the fineness of the yarn can be increased.

[0096] For example, in step E), the yarn is stretched by passing through a first draft roll having a linear stretching speed V2, V2 is selected such that the hot elongation D2 is 2 or less, and D2 = V2 / V1. The elongation D2 may be, for example, about 1.28, 1.05, 1.10, or 1.4. If the heating means is an oven through which the yarn passes, the oven may be located between the transfer roll and the first draft roll. Alternatively, the first draft roll may be a heated roll that is heated to a desired temperature. Through such hot elongation, a yarn can be obtained that possesses excellent elasticity while having significant fineness.

[0097] According to Step F), which is Step 6, the copolymer yarn obtained in Step E) undergoes cold stretching. The temperature of this cold stretching may be in the range of about 10°C to about 40°C, preferably about 20°C to about 25°C. Through this second cold stretching process, additional elasticity can be imparted to the yarn.

[0098] For example, in step F), the yarn is stretched by passing it through a second draft roll having a linear stretching rate V3, V3 is selected such that the cold elongation D3 is 1 or greater, and D3 = V3 / V2. The elongation D3 can be, for example, 1.10, 1.7, or about 2.83. Using such elongation in this step allows for obtaining a yarn with very good elasticity.

[0099] A method for manufacturing a thread to be used in the method according to the present invention may further include the following step G):

[0100] - G) A step of relaxing the copolymer yarn obtained in step F) at a temperature in the range of about 10°C to about 40°C, preferably about 20°C to about 25°C.

[0101] The relaxation temperature can be strictly lower than, for example, the glass transition temperature of the hard block of the copolymer.

[0102] In step G), the thread can be relaxed by passing through a winding roll having a linear speed V4 selected such that V4 / V3 is strictly less than 1, preferably about 0.97.

[0103] Afterwards, it can actually undergo additional stretching called post-stretch to improve its elastic return.

[0104] A method for manufacturing a thread to be used in the method according to the present invention may further include the following step H):

[0105] - H) A step of subjecting the copolymer yarn obtained in step F) or step G) to at least one post-stretching, for example, hot stretching at a temperature in the range of 30°C to 70°C, followed by cold relaxation at a temperature in the range of 20°C to 25°C.

[0106] Preferably, during post-stretching, the hot stretching elongation elongation ratio E1 is greater than 1.5, and the cold relaxation elongation relaxation ratio R3 = V3 / V4 is less than 1.3.

[0107] Copolymer yarns can undergo multiple post-stretching processes. Exposing the yarn to one or more post-stretching processes improves the yarn's elastic properties.

[0108] A method for manufacturing a thread to be used in the method according to the present invention may further include the following step I):

[0109] - I) A step of winding the yarn obtained in one of steps F), G), or H) onto a storage winder without stretching and without relaxation.

[0110] The yarn produced according to the manufacturing method described above comprises at least 50%, preferably at least 80%, more preferably at least 90%, and particularly about 100% of a thermoplastic copolymer based on the weight of the yarn.

[0111] The method according to the present invention comprises step 1°) of relaxing the yarn obtained in any one of steps F) to I) described above at a temperature in the range of about 70°C to about 110°C.

[0112] During this relaxation step, internal stress stored within the yarn during the manufacture of the yarn, as described above, is removed. Due to the removal of this internal stress, the yarn shrinks. Relaxation of the yarn can be obtained in-line during the continuous production process of the yarn through the extrusion process, or offline for yarn stored after production. Relaxation for yarn stored offline can be obtained by simple heat treatment of the yarn, namely by heating the yarn to a temperature in the range of about 70°C to about 110°C using a heating means. Relaxation of the yarn in-line can be obtained by passing the yarn over a heated roll: in this case, the roll can be heated to a temperature in the range of about 40°C to 125°C, preferably 40°C to 90°C, more preferably 45°C to 70°C.

[0113] The heating means may be any device capable of heating the room to a temperature in the range of about 70°C to about 110°C. Thus, the heating means may be selected from an oven, a steam chamber, and a water bath heated to 100°C.

[0114] In the case of the yarn obtained in step G), it will be understood that the yarn undergoes several relaxation processes at different temperatures.

[0115] For example, the yarn obtained in steps A) to F) and H) is treated with hot air at 70°C. Through this treatment, the elasticity of the yarn can be increased from 52% to 100%, and the elasticity is measured according to the method described in the example below.

[0116] Alternatively, the yarn obtained in steps A) through F) and H) is treated with hot air at 100°C. This treatment can increase the elasticity of the yarn from 52% to 200%, and the elasticity is measured according to the method described in the example below.

[0117] In one embodiment of the method according to the present invention, during step 1°), the yarn obtained in step F) passes through a first roll having a linear speed W1 and then passes through a second roll having a linear speed W2, wherein the linear speed W2 is strictly lower than the linear speed W1. In this embodiment, step 1°) of the method according to the present invention is performed directly and continuously on a yarn production line. In particular, while the yarn passes from the first roll to the second roll, it passes through the aforementioned heating means, e.g., an oven, a steam bath, or a boiling water bath. Furthermore, the first roll and the second roll may be heated to a temperature in the range of about 40°C to 125°C, preferably 40°C to 90°C, preferably 45°C to 70°C. In this embodiment, the relaxation of the yarn is achieved by both the heat treatment and the fact that the linear speed of the second roll is lower than the linear speed of the first roll, and this difference in speed also contributes to forcing the shrinkage of the yarn.

[0118] In another embodiment of the method according to the present invention, step 1°) comprises the following steps:

[0119] - 1°)a1), step F) i) winding the yarn obtained in step F) onto a perforated winding roll - the applied winding tension is selected to enable the yarn to contract as it is wound onto the winding roll -, then

[0120] - 1°)a2), step of placing the coiled roll with the thread wound on it into a steam room or boiling water bath.

[0121] In this embodiment, the perforations of the perforated winding roll allow the heat from the steam chamber or boiling water bath to optimally diffuse into the wound yarn. The steam chamber may be configured to supply steam to the perforated winding roll directly, e.g., through the center of the tube, or indirectly, e.g. by induction. In this embodiment, the relaxation of the yarn is achieved by both heat treatment and mechanical action that forces the shrinkage of the yarn in the winding roll.

[0122] In another embodiment of the method according to the present invention, during step 1), the yarn obtained in step I) is unwound from an initial storage winder at a first linear speed W3, and after passing through a heating medium, is wound onto a final storage winder at a linear speed W4, wherein the linear speed W4 is strictly lower than the linear speed W3.

[0123] In this embodiment, the heating medium is obtained using the aforementioned heating means, e.g., an oven, a steam bath, or a boiling water bath. In this embodiment, the relaxation of the yarn is achieved by both the heat treatment and the fact that the linear speed of the final storage winder is lower than the linear speed of the initial storage winder, and that this speed difference also contributes to forcing the shrinkage of the yarn.

[0124] In another embodiment of the method according to the present invention, where a yarn obtained by one of steps F) to I) is present in a fabric, step 1) includes the step of treating the fabric at a temperature in the range of about 70°C to about 110°C. For example, the fabric is treated as follows:

[0125] - purifying,

[0126] - stripping

[0127] - dyeing

[0128] You can receive one or more of them.

[0129] For example, the fabric can be washed at a temperature of about 90°C to 100°C for at least one hour. Through this treatment, the elastic properties of the fabric can be increased. Brief explanation of the drawing

[0130] Other features and advantages of the present invention will become more apparent from reading the following examples and the accompanying drawings: - [Fig. 1] is a diagram showing equipment capable of manufacturing a thread to be used in the method according to the present invention, and - [Fig. 2] is a diagram showing equipment capable of applying post-stretching to a yarn manufactured with the equipment of Fig. 1, and - [Fig. 3] is a graph showing a curve representing the tensile force (cN) as a function of elongation (%) for two threads: one that is not treated by the method according to the present invention and one that is treated by the method according to the present invention; - [Fig. 4] is a diagram showing the knitting structure of a fabric to be used in the method according to the present invention, and - [Fig. 5] is a graph showing a curve representing the tensile force (N) in the inclination direction as a function of tensile strain (or displacement) (%) for a knit not treated by the method according to the present invention, and - [Fig. 6] is a graph showing a curve representing the tensile force (N) in the inclination direction as a function of tensile strain (or displacement) (%) for a knit treated by the method according to the present invention, and - [Fig. 7] is a graph showing a curve representing the tensile force (N) in the weft direction as a function of tensile strain (or displacement) (%) for a knit not treated by the method according to the present invention, and - [Fig. 8] is a graph showing a curve representing the tensile force (N) in the weft direction as a function of tensile strain (or displacement) (%) for a knit treated by the method according to the present invention, and - [Fig. 9] is a graph showing a curve representing the tensile force (N) in the diagonal direction as a function of tensile strain (or displacement) (%) for a knit not treated by the method according to the present invention, and - [Fig. 10] is a graph showing a curve representing the tensile force (N) in the diagonal direction as a function of tensile strain (or displacement) (%) for a knit treated by the method according to the present invention, and - [Fig. 11] is a graph showing the hysteresis curve in the slope direction for a knit not treated by the method according to the present invention, and - [Fig. 12] is a graph showing the hysteresis curve in the weft direction for a knit not treated by the method according to the present invention, and - [Fig. 13] is a graph showing the hysteresis curve in the slope direction for a knit treated by the method according to the present invention, and - [Fig. 14] is a graph showing the hysteresis curve in the weft direction for a knit treated by the method according to the present invention, and - [Fig. 15] is a bar graph showing the tensile force in different charge and discharge extensions in the inclined direction for a knit not treated by the method according to the present invention and a knit treated by the method according to the present invention, - [Fig. 16] is a bar graph showing tensile strength in different charge and discharge extensions in the weft direction for a knit not treated by the method according to the present invention and a knit treated by the method according to the present invention. Specific details for implementing the invention

[0131] Referring to FIG. 1, equipment (100) capable of manufacturing a thread to be used in the method according to the present invention is shown.

[0132] The equipment (100) includes a spinneret (1) comprising an extruder (2) and a spinning pack (3). Additionally, the equipment (200) includes a pair of transfer rolls (4), a pair of draft rolls (5), and an initial storage winder (6).

[0133] The extruder (2) includes an inlet (2a) and an outlet (2b), as well as a feed hopper (7).

[0134] Now, referring to Figure 1, the steps of the actual manufacturing method will be explained.

[0135] Step A)

[0136] A thermoplastic copolymer pellet is provided. The pellet is fed into the extruder (2) through the feed hopper (7) at the inlet (2a) of the extruder (2). Inside the extruder (2), the pellet is kneaded and melted. At the outlet (2b) of the extruder (2), the molten elastomer is obtained and transported to a spinning pack (3) through a transport line formed by an insulating metal pipe (8).

[0137] Step B)

[0138] The spinning pack (3) includes a metering pump, a filter, and a spinneret (9). The metering pump controls the flow rate of the molten elastomer to the spinneret (9).

[0139] The molten elastomer passes through a filter and is injected into a spinneret (9). The spinneret (9) has multiple holes. Two threads (10) are formed at the outlet of the spinneret (9), and each thread (10) contains multiple filaments. The two threads (10) are combined into a single thread (11) in a unit (12) configured to guide these two threads (10) into a single thread (11) and apply fabric oil to the thread (11).

[0140] Step C)

[0141] The seal (11) can be cooled to a temperature in the range of about 10°C to about 40°C, preferably about 20°C to about 25°C, for example through air quenching.

[0142] Step D)

[0143] Once cooled, the thread (11) passes through a transfer roll (4) and undergoes preliminary stretching at a temperature in the range of about 10°C to about 40°C, preferably about 20°C to about 25°C.

[0144] Step E)

[0145] Then, the thread (11) passes through a draft roll (5) and undergoes hot stretching at a temperature ranging from about 40°C to about 125°C, preferably from about 45°C to about 90°C.

[0146] Step F)

[0147] The thread (11) passes through the draft roll (5) and undergoes cold stretching at a temperature ranging from about 10°C to about 40°C, preferably from about 20°C to about 25°C.

[0148] Step I)

[0149] Finally, the thread (11) is wound onto an initial winding roll (6). A 12-filament thread with a count of 60 dtex is obtained.

[0150] Referring to FIG. 2, equipment (200) capable of performing a post-stretching step and a relaxation step following the extrusion, pre-stretching, hot-stretching, and cold-stretching steps described in FIG. 1 is shown. The yarn (11) is wound and stored on an initial storage winder (6).

[0151] Therefore, the post-stretching and relaxation steps described in Fig. 2 correspond to the optional step H) described above.

[0152] The equipment (200) includes a pair of heated first post-draft rolls (12), a pair of second post-draft rolls (13), a pair of third post-draft rolls (14), a fourth post-draft roll (15), and a final winding roll (16).

[0153] The thread (11) is unwound from the initial storage winder (6) and passes through the first post-draft roll (12), the second post-draft roll (13), the third post-draft roll (14), and the fourth post-draft roll (15) in sequence. Then the thread (11) is sent to the final storage winder (16).

[0154] The temperature and linear velocity of the post-draft roll are summarized in Table 1 below:

[0155]

[0156] Accordingly, the yarn (11) undergoes hot post-stretching as it passes through the roll (12). Then, it undergoes relaxation as it passes from the roll (13) to the roll (15).

[0157] The final post-stretch count is 50 + / - 3 dtex.

[0158] Examples

[0159] In all of the following examples, mechanical properties were measured according to the BISFA 2015 standard. Tests were performed at a constant elongation speed on a mechanical test bench using Tensolab software. The filament samples were placed 5 cm apart between two compressed air jaws. The upper jaw moved at a speed of 500 mm / min.

[0160] In all of the following examples, viscoelastic properties were measured as follows: Tests were performed at 100% elongation on a mechanical test bench using Tensolab software according to the BISFA Bare Elastic Yarn 2015 standard. Yarn samples were placed between two clamps spaced 10 cm apart under compressed air. Five measurements were taken. To obtain more accurate results, the average of the five measurements can be calculated.

[0161] Example 1

[0162] A yarn was produced according to the method described in FIGS. 1 and 2 using a copolymer composed of a polyamide block and a polyether block sold by Arkema under the trade name "PEBAX RNEW 35R53 SP 01". The polyamide block of this copolymer was a PA 11 block, and the polyether block was a block derived from polytetramethylene glycol.

[0163] This elastomeric copolymer had the following characteristics:

[0164] - Density of 1020 kg / m³ when measured according to ISO 1183 standard 3 ,

[0165] - 25 Shore D hardness at 15 seconds when measured according to ISO 7619-1 standard,

[0166] - Melting point 135℃ when measured according to ISO 11357-1 / -3 standard,

[0167] - Content of bio-derived components, such as PA 11 polyamide, is 29% when measured according to ASTM D6866 standard.

[0168] Accordingly, the produced yarn was manufactured by performing steps A) through F) and then step H) in accordance with the above description. A 12-filament yarn with a count of 60 dtex was obtained. This yarn is hereinafter referred to as "Yarn 1".

[0169] To evaluate the mechanical properties of Thread 1, this thread was subjected to various heat treatments as follows:

[0170] - Unheat-treated yarn 1, "Unbleached yarn": 5 samples of this yarn were tested, and

[0171] - Yarn 1 treated according to the method of the present invention, more specifically, yarn 1 subjected to hot air heat treatment at 70°C: 5 samples of this yarn were tested, and

[0172] - Yarn 1 processed according to the method of the present invention, more specifically, yarn 1 subjected to hot air heat treatment at 100°C: 5 samples of this yarn were tested.

[0173] Figure 3 shows the curve representing the tensile force (cN) for the three tests above as a function of elongation (%). In Figure 3:

[0174] - The left curve corresponds to the unbleached sand, and

[0175] - The middle curve corresponds to thread 1 processed at 70℃, and

[0176] - The curve on the right corresponds to thread 1 processed at 100℃, and

[0177] - The gray area at the bottom left represents the elastic region of the curve.

[0178] The results are summarized in Table 2 below.

[0179]

[0180] These results show that the fracture strain of yarn 1 increases after heat treatment according to the method of the present invention. In addition, the fracture strain increased with increasing application temperature. Accordingly, the same trend was observed in the elastic strain (gray area in Fig. 3), and compared to the elastic modulus of 52% of the initial unbleached yarn that was not heat-treated, the elastic modulus of yarn 1 treated at 70°C increased to 100%, and the elastic modulus of yarn 1 treated at 100°C increased to 200%.

[0181] Example 2

[0182] From the untreated yarn 1 of Example 1, yarn 1 was combined with a 78 dtex, 23-filament textured PA66 polyamide yarn to produce yarn 2. The yarn 2 produced in this way is suitable for woven knitting.

[0183] Accordingly, the inventors produced a knit using yarn 2 according to the jersey knitting weave shown in FIG. 4. In FIG. 4, arrow A indicates the direction of the warp, arrow B indicates the direction of the weft, and arrow C indicates the diagonal direction.

[0184] The generated knit is processed as follows:

[0185] - Wash in a dishwasher at 98℃ for 2 hours and 40 minutes,

[0186] - Dry in a dryer at 60℃ for 2 hours and 30 minutes

[0187] Received.

[0188] The mechanical and elastic properties of an untreated initial knit (hereinafter Knit 0) and a knit treated by the method according to the present invention (washed and dried as described above) (hereinafter Knit 1) were tested according to the following method:

[0189] - Determination of maximum tensile strength and elongation of knitsThe principle of this test was to stretch the specimen at a constant rate until it broke. To this end, the fabric was exposed to a temperature of (20 ± 2)°C and a relative humidity of (65 ± 4)% for 24 hours. Then, five specimens were cut in the warp direction with a length of 300 mm and a width of 50 mm, and five specimens were cut in the weft direction. Each specimen was secured between two clamps of a dynamometer. The upper clamp was moved upward until the sample broke. The tensile strength-elongation curve was recorded.

[0190] - Monitoring of elastic properties of elastic fabrics The principle of this test was to stretch the components during three charge-discharge cycles with a fixed charge. To this end, the fabric was exposed to a temperature of (20 ± 2)°C and a relative humidity of (65 ± 4)% for 2 hours. First, the inventors cut three test specimens with a length of 150 mm and a width of 50 mm in the warp direction and three test specimens in the weft direction. Each test specimen was fixed between two clamps of a dynamometer (the lower clamp was fixed and the upper clamp was movable). The initial distance between the clamps was 100 mm. Then, three charge-discharge cycles were performed while recording the tensile-elongation curve. In each cycle, the upper clamp was raised until the tensile force reached 15 N (charge phase), and then lowered to the initial length of the test specimen (discharge phase). After three charge-discharge cycles, the tensile-elongation curve representing the stretching characteristics of the elastic fabric was plotted.

[0191] mechanical properties

[0192] Figures 5 and 7 are graphs showing curves representing the tensile force (N) in the warp and weft directions for knit 0, respectively, as a function of tensile strain (or displacement) (%).

[0193] Figures 6 and 8 are graphs showing curves representing the tensile force (N) in the warp direction and weft direction for knit 1, respectively, as a function of tensile strain (or displacement) (%).

[0194] Figure 9 is a graph showing a curve representing the tensile force (N) in the diagonal direction for knit 0 as a function of tensile strain (or displacement) (%).

[0195] Figure 10 is a graph showing a curve representing the tensile force (N) in the diagonal direction for knit 1 as a function of tensile strain (or displacement) (%).

[0196] The results are summarized in Table 3 below:

[0197]

[0198] These results show that the fracture strain of Knit 1, treated by the method according to the present invention, is much better than the fracture strain of Knit 0, which was not treated by the method according to the present invention. Accordingly, the fracture strain of Knit 1 increased by 32% in the warp direction, 26% in the weft direction, and 38% in the diagonal direction compared to Knit 0.

[0199] Elastic properties

[0200] Figures 11 and 12 are graphs showing the hysteresis curves in the warp and weft directions, respectively, for knit 0.

[0201] Figures 13 and 14 are graphs showing the hysteresis curves in the warp and weft directions, respectively, for knit 1.

[0202] Using these curves, we were able to create a bar graph showing the changes in elastic properties of Knit 0 and Knit 1. Therefore,

[0203] - FIG. 15 is a bar graph showing tensile force according to different charge and discharge elongation rates in the inclined direction for knit 0 and knit 1, and

[0204] - Figure 16 is a bar graph showing tensile force according to different charge and discharge elongation rates in the weft direction for knit 0 and knit 1.

[0205] In these diagrams:

[0206] - For example, the expression "30% strain (filling)" means a 30% extension (elongation) in the filling curve (upper curve) of the hysteresis curves in FIGS. 11 to 14, and

[0207] - For example, the expression "40% strain (discharge)" means a 40% extension (elongation) in the discharge curve (lower curve) of the hysteresis curves in FIGS. 11 to 14, and

[0208] - In each indicated extended position, the left bar corresponds to knit 0 and the right bar corresponds to knit 1.

[0209] These diagrams show that the tensile strength of Knit 1 increased compared to Knit 0 at any elongation percentage in both charging and discharging.

[0210] For example, referring to the diagram in Fig. 15, when considering a 30% extension in the filled state, it can be seen that the force required to extend the knit to 30% of its original length increased from 1.9 N for Knit 0 to 2.8 N for Knit 1. This means that, given the elasticity, Knit 1 exhibits a higher holding force than Knit 0.

[0211] The same trend could be observed in the discharge direction as well. The force required to relax the knit to 30% of its original length increased from 0.4 N for Knit 0 to 0.9 N for Knit 1. This means that, at a given elasticity, Knit 1 exhibits a higher holding force than Knit 0.

[0212] The same trend was observed in 40%, 70%, and 100% extensions.

[0213] As can be seen from the results of the present example, the method according to the present invention can improve the elasticity (greater elongation at break) of a fabric containing yarns prepared according to steps A) through F) described above. These results also show that the method according to the present invention can improve the elastic modulus (i.e., the required force) required to stretch or relax a fabric containing yarns prepared according to steps A) through F) described above.

[0214] The method according to the present invention can improve the elasticity level of a fabric comprising yarns prepared according to steps A) to F) described above in all directions (e.g., in the case of knits, in the warp direction, weft direction, and diagonal direction). In addition, the method according to the present invention can impart superior retention properties to such fabrics.

Claims

Claim 1 - A) A step of feeding thermoplastic copolymer pellets into an extruder to obtain a molten elastomer of the copolymer by extrusion - the hardness of the copolymer is in the range of 10 to 61 ShD when measured according to Standard 7619-1 -,- B) A step of obtaining copolymer threads by spinning the molten elastomer obtained in step A) within the spinneret of a spinning pack, - C) a step of cooling the copolymer yarn obtained in step B) at the spinneret exit to a temperature in the range of about 10°C to about 40°C, preferably about 20°C to about 25°C, - D) A step of pre-stretching the yarn obtained in step C) at the temperature of step C),- E) a step of hot stretching the yarn obtained in step D) at a temperature in the range of about 40°C to about 125°C, preferably about 45°C to about 90°C, - F) A step of cold stretching the yarn obtained in step E) at a temperature in the range of about 10°C to about 40°C, preferably about 20°C to about 25°C, - G) Optionally, a step of relaxing the yarn obtained in step F) at a temperature in the range of about 10°C to about 40°C, preferably about 20°C to about 25°C, - H) Optionally, a step of applying at least one post-stretch to the yarn obtained in step F) or step G), comprising hot stretching at a temperature in the range of, for example, 30°C to 70°C, followed by cold relaxing at a temperature in the range of, for example, 20°C to 25°C, - A method for increasing the elastic properties of a yarn obtained by a melt spinning process, comprising: I) optionally, winding the yarn obtained from one of steps F), G), or H) onto an initial storage winder without stretching and without relaxation, wherein the method comprises step 1) relaxing the yarn obtained from any one of steps F) to I) at a temperature in the range of about 40°C to about 110°C. Claim 2 The method according to claim 1, wherein the thermoplastic copolymer is a copolymer having a polyamide block and a polyether block, the polyamide block is selected from PA 11, PA 12, PA 1010, PA 1014, copolymers thereof and mixtures thereof, the polyether block is a block derived from polytetramethylene glycol, and the hardness of the copolymer is 22 to 61 ShD, preferably 22 to 55 ShD, more preferably 22 to 40 ShD when measured according to standard 7619-1. Claim 3 A method according to claim 2, characterized in that the polyamide block is selected from PA 11, PA 12, copolymers thereof, and mixtures thereof. Claim 4 A method according to paragraph 3, characterized in that the polyamide block is a PA 11 block. Claim 5 The method according to claim 1, wherein the thermoplastic copolymer is selected from thermoplastic elastomers (TPE), thermoplastic polyurethane elastomers, thermoplastic polyolefin elastomers (POE), polyphthalamide (PPA), polyether-esteramide elastomers, thermoplastic copolyester elastomers, copolyester (ether) elastomers, and mixtures thereof, and the hardness of the copolymer is 10 to 57 ShD, preferably 10 to 45 ShD, preferably 10 to 35 ShD, more preferably about 22 ShD when measured according to standard 7619-1. Claim 6 A method according to claim 5, wherein the copolymer is selected from a copolymer comprising a flexible block and a hard block, the flexible block is a polyether block derived from polytetramethylene glycol (PTMEG), and the hard block is selected from a diisocyanate block and a polyester block. Claim 7 A method according to claim 6, characterized in that the copolymer is selected from a copolymer in which the flexible block is a polyether block derived from polytetramethylene glycol and the hard block is a polyester block. Claim 8 In claim 7, the method is characterized in that the copolymer having a polyether block and a polyester block is a compound of the following formula (I): In chemical formula (I), y=0.3x. Claim 9 A method according to any one of claims 1 to 8, characterized in that step 1) is performed at a temperature in the range of about 80°C to about 100°C, preferably about 90°C to about 100°C. Claim 10 A method characterized in that, in any one of claims 1 to 9, the thread obtained at the end of steps A) to F) and H) is treated with hot air at 70°C. Claim 11 A method characterized in that, in any one of claims 1 to 9, the thread obtained at the end of steps A) to F) and H) is treated with hot air at 100°C. Claim 12 A method according to any one of claims 1 to 9, wherein during step 1°), the thread obtained in step F) is passed over a first roll having a linear speed W1 and then passed over a second roll having a linear speed W2, wherein the linear speed W2 is strictly lower than the linear speed W1. Claim 13 In any one of paragraphs 1 through 9, step 1°) is - 1°)a1), step of i) winding the yarn obtained in step F) onto a perforated winding roll - the applied winding tension is selected to enable the yarn to contract as it is wound onto the winding roll -, and the subsequent- 1°)a2), a method characterized by including the step of placing a coiled roll with a thread wound on it into a steam chamber or a boiling water bath. Claim 14 A method according to any one of claims 1 to 9, wherein during step 1°), the yarn obtained in step I) is unwound from an initial storage winder at a first linear speed W3, passes through a heating medium, and is wound onto a final storage winder at a linear speed W4, wherein the linear speed W4 is strictly lower than the linear speed W3. Claim 15 A method according to any one of claims 1 to 9, wherein the yarn obtained in one of steps F) to I) is present in a textile, and step 1) comprises treating the textile at a temperature in the range of about 70°C to about 110°C. Claim 16 In Item 15, the above fabric is treated as follows:- purifying,- Stripping A method characterized by receiving one or more of the dyes.

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