Preparation method of high-elastic polyester yarn

Abstract

The invention provides a preparation method of a high-elastic polyester yarn, which comprises the following steps: S10: providing a pre-oriented yarn which is composed of a polyethylene glycol terephthalate component and a polybutylene terephthalate component, the polyethylene glycol terephthalate component and the polybutylene terephthalate component are distributed on the cross section in a parallel or eccentric skin-core manner; s20, the pre-oriented yarn is fed into a false twist texturing machine; s30, enabling the yarns to pass through a texturing hot box of a false twist texturing machine, wherein the temperature of the texturing hot box is set to be 240-255 DEG C; s40, the running tension of the yarn in the deformation hot box is controlled to range from 0.5 cN to 2.0 cN by adjusting the speed ratio of feeding to output; and S50, after the yarn leaves the deformation hot box and before the yarn enters the false twister, the yarn is cooled through a water bath cooling device, and the water temperature of the water bath cooling device is 20-25 DEG C. The polyester yarn prepared through the preparation method is high in structural stability, and the elastic recovery rate and the bulkiness are not prone to being reduced.

Description

Technical Field

[0001] This invention relates to the field of polyester yarn preparation technology, and more specifically to a method for preparing high-elastic polyester yarn. Background Technology

[0002] Polyester fiber (PET) is widely used in sportswear and casual wear fabrics due to its high strength, abrasion resistance, and quick-drying properties. However, because conventional polyester fibers have high crystallinity, high modulus, and smooth surface, fabrics made from them typically have a stiff hand feel and lack the fluffiness and high resilience of spandex or natural fibers. To improve the hand feel and elasticity of polyester fibers, existing technologies typically employ the friction false twist (DTY) process. This process imparts a certain degree of fluffiness to the yarn through a "heat-twist-cool-untwist" step. However, polyester yarns produced by this process have poor structural stability. After the yarn or fabric undergoes high-temperature dyeing or washing, the crimped structure may loosen or straighten, leading to a decrease in the fabric's elastic recovery rate and fluffiness. Summary of the Invention

[0003] The purpose of this invention is to overcome the above-mentioned defects or problems in the prior art and provide a method for preparing high-elastic polyester yarn. The polyester yarn prepared by this method has strong structural stability and its elastic recovery rate and bulkiness are not easily reduced.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: Technical Solution 1: A method for preparing high-elastic polyester yarn, comprising the following steps: S10: providing pre-oriented yarn, wherein the pre-oriented yarn is composed of polyethylene terephthalate (PET) and polybutylene terephthalate (PB), and the PET and PB components are distributed in a parallel or eccentric core-sheath pattern in cross-section; S20: feeding the pre-oriented yarn into a false-twist texturing machine; S30: passing the yarn through the texturing heat chamber of the false-twist texturing machine, wherein the texturing... The temperature of the heat box is set to 240°C to 255°C; S40: By adjusting the feed-to-output speed ratio, the running tension of the yarn in the heat box is controlled to be 0.5cN to 2.0cN, so that the polybutylene terephthalate component relative to the polyethylene terephthalate component undergoes thermal shrinkage and crimping; S50: After the yarn leaves the heat box and before entering the false twister, the yarn is cooled by a water bath cooling device, the water temperature of which is 20°C to 25°C.

[0005] Technical Solution 2 based on Technical Solution 1: In step S10, the intrinsic viscosity of the polyethylene terephthalate component is 0.66 dl / g, and the intrinsic viscosity of the polybutylene terephthalate component is 0.65 dl / g.

[0006] Technical Solution 3 based on Technical Solution 1: In step S10, the mass ratio of the polyethylene terephthalate component to the polybutylene terephthalate component is 1:(0.3-1); and the two components merge in the spinneret orifice or at the micropore outlet to form a non-encapsulated parallel structure.

[0007] Technical solution four based on technical solution one: also includes step S05: before preparing the pre-oriented yarn, polyethylene terephthalate chips and polybutylene terephthalate chips are vacuum dried at a temperature of 80°C to 90°C to reduce the moisture content to less than 50 PPM.

[0008] Technical Solution 5 based on Technical Solution 1: The preparation process of the pre-oriented yarn in step S10 includes: melting and extruding the polyethylene terephthalate component at a temperature of 190°C to 210°C, melting and extruding the polybutylene terephthalate component at a temperature of 190°C to 220°C, and winding it at a spinning speed of 800 m / min to 1500 m / min.

[0009] Technical Solution Six based on Technical Solution One: In step S30, the residence time of the yarn in the deformation heat box is 0.1 seconds to 0.5 seconds.

[0010] Technical solution seven based on technical solution one: In step S50, the cooling time of the yarn in the water bath cooling device is 0.3 seconds to 0.8 seconds; and after the yarn leaves the water bath cooling device, the water adhering to the surface of the yarn is removed by an air nozzle.

[0011] Technical solution eight based on technical solution one: In step S40, the running tension is controlled by adjusting the speed ratio between the feed roller and the intermediate roller of the false twisting deformer.

[0012] Technical solution nine based on technical solution one: In step S20, the rotation speed of the false twister is set to 80,000 rpm to 100,000 rpm.

[0013] Technical solution ten based on technical solution one also includes step S60: winding the yarn after false twisting and deformation treatment at a winding speed of 500m / min to 800m / min and a winding tension of 0.5cN to 1.5cN.

[0014] As can be seen from the above description of the present invention, compared with the prior art, the present invention has the following beneficial effects: Technical Solution 1 provides a method for preparing high-elastic polyester yarn. The yarn produced by this method exhibits strong structural stability, and its elastic recovery rate and bulkiness do not easily decrease even after high-temperature dyeing and washing processes. Specifically, the preparation method provided in this solution is based on a bicomponent parallel or eccentric core-sheath structure of polyethylene terephthalate (PET) and polybutylene terephthalate (PBT), with the temperature of the texturing chamber set between 240℃ and 255℃. This temperature is close to the melting point of the PBT component. At this temperature, the PBT component softens upon heating, eliminating the internal stress generated during spinning and acquiring the ability to shrink. The key is controlling the running tension of the yarn within the texturing chamber to between 0.5cN and 2.0cN. In existing false-twist texturing processes, tensions exceeding 15cN are typically applied to prevent yarn vibration. This high tension straightens the yarn. When the yarn is straightened, even if the PBT component is heated, its shrinkage is inhibited by external forces and cannot proceed fully. Therefore, existing processes primarily rely on mechanical torsional forces to generate yarn crimp, leaving residual stress within the yarn. This mechanically formed crimp tends to straighten upon subsequent heating. This solution utilizes low tension to alleviate yarn shrinkage, causing the PBT component to shrink relative to the PET component at high temperatures. Since the two components are arranged side-by-side or eccentrically in cross-section, the shrinkage of the PBT component causes the yarn to bend, forming a helical structure. Because this helical structure is generated by the material's own shrinkage difference, rather than by external mechanical torsion, its structural stability is better. It should be noted that although this solution uses a low tension range, this tension limits and causes yarn vibration during operation. This is because at high temperatures of 240℃ to 255℃, the PBT component undergoes severe thermal shrinkage. This severe shrinkage consumes the relaxation provided by the low-tension feed, resulting in an internal shrinkage force driven by thermal shrinkage within the heating chamber. This internal shrinkage force maintains tension within the yarn, thus counteracting the relaxation effect of the external low tension and preventing yarn vibration within the heating chamber. Building upon this, this method further cools the yarn using a water bath at 20°C to 25°C after it leaves the heating chamber and before it enters the false twister. Existing processes typically employ natural air cooling or metal plate contact cooling, which results in relatively slow cooling rates. Since this method sets the heating temperature at 240°C to 255°C, the yarn is in a softened state upon leaving the heating chamber. If the cooling rate is too slow, the polymer chain segments will loosen and rearrange, causing the helical structure already formed in the heating zone to loosen or straighten. This method utilizes the thermal conductivity of water to rapidly cool the yarn, lowering its temperature below its glass transition temperature within a short time. This rapid cooling fixes the helical shape formed under high temperature and low tension, preventing structural loosening. Therefore, the yarn prepared by the method provided in this scheme has a stable helical crimp structure.During subsequent fabric dyeing, finishing, or washing processes, the yarn's crimped structure is less likely to disintegrate due to stress release, thus maintaining a high elastic recovery rate.

[0015] In Technical Solution 2, the intrinsic viscosities of the polyethylene terephthalate (PET) and polybutylene terephthalate (PET) components are defined. A specific viscosity-matching design ensures that the rheological properties of the two polymer melts are similar during composite spinning. If the viscosity difference between the two components is too large, problems such as weak interfacial bonding, bending deflection, or unstable spun yarn may easily occur during parallel composite spinning. The viscosity range selected in this solution allows the two components to form a stable laminar composite within the spinneret, with strong interfacial bonding, preventing component peeling or splitting during subsequent high-temperature deformation processing. Simultaneously, the PBT component within this viscosity range possesses sufficient fluidity at high temperatures to eliminate internal stress while maintaining the necessary melt strength to support the formation of the helical structure, thereby ensuring the uniformity of the yarn and the regularity of the crimp structure.

[0016] In technical solution three, the mass ratio of PET to PBT is limited, and the two are defined as a non-coated side-by-side structure. In this asymmetrical ratio and structure, the dominant PET component provides the physical rigidity and support of the yarn, preventing it from becoming too soft and collapsing due to excessive shrinkage. The moderately proportioned PBT component provides sufficient thermal shrinkage driving force to form a highly elastic spiral. The non-coated side-by-side structure allows both components to be exposed on the fiber surface, enabling direct contact with cooling water for rapid heat exchange and maximizing the crimping effect caused by differences in thermal shrinkage.

[0017] In technical solution four, vacuum drying is performed before spinning to prevent the polyester material from undergoing hydrolysis in a high-temperature molten state.

[0018] Technical Solution 5 specifies the relevant spinning parameters. The pre-oriented yarn prepared by this parameter combination has low crystallinity and orientation. In subsequent texturing, the low-crystallinity pre-oriented yarn has a looser internal structure, making it easier to be softened and rearranged at high temperatures in the texturing chamber. This lowers the initial stress threshold for texturing, allowing sufficient deformation to be induced under low tension of 0.5 cN to 2.0 cN, ensuring the feasibility of the process.

[0019] In technical solution six, the residence time of the yarn in the deformation heat box is limited to ensure that the yarn only undergoes the necessary thermoplastic reconstruction and avoids structural damage due to overheating.

[0020] In technical solution seven, a water bath cooling time is specified, and water is removed using air nozzles. Sufficient water bath cooling time can rapidly cool the yarn temperature below its glass transition temperature, while air nozzle water removal ensures a dry friction state during the false twisting process, guaranteeing consistent twisting efficiency and product quality.

[0021] In technical solution eight, the running tension is controlled by adjusting the speed ratio between the feed roller and the intermediate roller. By giving the yarn a certain overfeed, the length loss of the PBT component caused by heat shrinkage is pre-compensated, so that the yarn is always in a slightly relaxed state of 0.5cN to 2.0cN macroscopically.

[0022] In technical solution nine, the rotational speed of the false twister is limited. A higher speed provides stronger twisting torque, ensuring sufficient twist even under low tension, thus regularizing the helical structure. Furthermore, the centrifugal force generated by high-speed rotation helps stabilize the yarn's trajectory, and combined with the damping effect of the water bath, further suppresses potential air pocket vibrations under low tension. The high twist resulting from the high rotational speed makes the formed helical structure more compact and dense, improving the yarn's final resilience.

[0023] In technical solution ten, the winding speed and winding tension are limited. Lower winding tension can maximize the preservation of the fluffy state and spiral structure of the yarn during the deformation process, prevent secondary damage during the bobbin forming process, and ensure the high elastic recovery rate of the final product. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments are briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the polyester yarn provided in Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the polyester yarn provided in Comparative Example 1 of the present invention. Detailed Implementation

[0026] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are preferred embodiments of the present invention and should not be considered as excluding other embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0027] In the claims, description and accompanying drawings of this invention, the terms "comprising," "having," and variations thereof are used to mean "including but not limited to."

[0028] This invention relates to a method for preparing high-elastic polyester yarn, which mainly includes the following steps: S10: Provide a pre-oriented yarn, the pre-oriented yarn being composed of a polyethylene terephthalate component and a polybutylene terephthalate component, wherein the polyethylene terephthalate component and the polybutylene terephthalate component are distributed in a side-by-side or eccentric core-and-shell pattern in cross-section. S20: Feed the pre-oriented yarn into the false twist texturer; S30: Pass the yarn through the texturing chamber of the false twist texturing machine, the temperature of which is set to 240°C to 255°C; S40: By adjusting the feed-to-output speed ratio, the running tension of the yarn in the deformation heat box is controlled to be 0.5cN to 2.0cN, so that the polybutylene terephthalate component relative to the polyethylene terephthalate component undergoes thermal shrinkage and curling. S50: After the yarn leaves the texturing heat box and before it enters the false twister, the yarn is cooled by a water bath cooling device, the water temperature of which is 20°C to 25°C.

[0029] The following is a detailed explanation of each of the above steps.

[0030] First, step S10 will be explained in detail. Step S10 mainly involves the preparation of pre-oriented yarns.

[0031] In step S10, the pre-oriented yarn is composed of two polymer components: polyethylene terephthalate (PET) as the first component and polybutylene terephthalate (PBT) as the second component. The intrinsic viscosity of the PET component is selected as 0.66 dl / g, and the intrinsic viscosity of the PBT component is selected as 0.65 dl / g. This similar viscosity design ensures that the rheological properties of the two melts are matched during the composite spinning process, thereby forming a stable two-phase interface within the fiber and preventing delamination during subsequent high-temperature processing.

[0032] Before melt spinning, the raw material chips need to be dried to remove moisture from both the inside and the surface of the chips. Specifically, polyethylene terephthalate (PET) chips and polybutylene terephthalate (PET) chips are placed separately into a vacuum drum dryer. The drying temperature is controlled between 80°C and 90°C, and the drying time is adjusted flexibly according to the initial moisture content of the chips, typically continuing until the moisture content of the chips drops below 50 PPM.

[0033] After drying, the two types of PET chips were fed into two separate screw extruders for melt plasticization. The first extruder processed the polyethylene terephthalate (PET) component, with its heating temperature set between 190°C and 210°C in each section to ensure the PET chips were fully melted into a homogeneous fluid. The second extruder processed the polybutylene terephthalate (PET) component, with its heating temperature set between 190°C and 220°C. It is important to note that the extrusion temperatures here are relatively low to minimize polymer thermal degradation while maintaining melt flowability.

[0034] The two molten polymer fluids are metered by their respective metering pumps and then enter the composite spinning box. A specially designed composite spinneret is installed in the spinning box. The internal flow channel design of this spinneret determines the cross-sectional shape of the fiber. In this embodiment, the polyethylene terephthalate (PET) component and the polybutylene terephthalate (PET) component are guided by the flow channel to converge within the micro-orifice guide holes or at the micro-orifice inlet of the spinneret, and extruded from the spinneret orifice in a parallel or eccentric core-and-shell configuration. A non-coated parallel structure is preferred, meaning both components are exposed on the fiber surface, and the mass flow ratio of the two components is controlled within the range of 1:(0.3-1).

[0035] The high-temperature molten stream extruded from the spinneret enters a side-blowing cooling device. Under the action of the side-blowing air, the molten stream rapidly cools and solidifies into nascent fibers. The temperature of the cooling air is typically controlled between 15°C and 25°C, and the air velocity is controlled between 0.4 m / s and 0.6 m / s to ensure uniform cooling of the fiber bundle. The solidified fibers are then oiled by an oiling device to impart fiber bundledness and smoothness, and reduce static electricity. Finally, the fibers are wound into a bobbin by a winding head, thus obtaining pre-oriented yarn. In this embodiment, the winding speed is controlled between 800 m / min and 1500 m / min. Using this relatively low winding speed results in pre-oriented yarn with a lower degree of orientation and crystallinity, and a relatively loose internal structure.

[0036] Next, step S20 will be described in detail. Step S20 is the process of introducing the pre-oriented yarn prepared in step S10 into the false twist texturer for subsequent processing.

[0037] First, the bobbin wound with pre-oriented yarn is placed on the unwinding frame of the false-twist texturing machine. To ensure a smooth unwinding process, tangential or axial unwinding is typically used to allow the yarn to unwind smoothly from the bobbin. The unwound yarn is guided by a yarn guide to eliminate fluctuations in the unwinding air ring, and then fed into the first roller of the false-twist texturing machine, i.e., the feed roller. The feed roller's function is to continuously transport the yarn to the subsequent processing area at a set speed. In this embodiment, the false-twist texturing machine is equipped with core components such as a texturing heat box, a water bath cooling device, and a false twister. Before the yarn begins formal processing, or while the yarn is being introduced into the machine, the operating parameters of the equipment need to be set. The speed of the false twister is set to 80,000 rpm to 100,000 rpm.

[0038] Next, step S30 will be described in detail. Step S30 mainly involves the heating process of the yarn on the false-twist texturing machine. The yarn, after being conveyed by the feed rollers, then enters the texturing heating chamber. The texturing heating chamber is a device on the false-twist texturing machine used for contact or non-contact heating of the moving yarn. In this embodiment, the heating temperature of the texturing heating chamber is set to 240°C to 255°C. In this embodiment, the residence time of the yarn in the texturing heating chamber is controlled within the range of 0.1 seconds to 0.5 seconds.

[0039] Next, step S40 will be explained in detail.

[0040] Step S40 involves precisely controlling the running tension of the yarn as it passes through the texturing chamber to induce thermal shrinkage curling. In this embodiment, this tension control is achieved by adjusting the speed ratio between the feed roller and the intermediate roller of the false-twist texturing machine. Normally, to obtain stable processing tension, the speed of the subsequent roller is slightly higher than that of the preceding roller. However, in this invention, to achieve an extremely low running tension of 0.5 cN to 2.0 cN, an overfeed control strategy is employed. This involves providing a certain length compensation to the yarn based on its shrinkage tendency at high temperatures, resulting in a slightly relaxed state macroscopically. Specifically, when the yarn is in the high-temperature environment of 240°C to 255°C within the texturing chamber, the polybutylene terephthalate (PET) component exhibits a strong tendency to shrink. Since the running tension is limited to the range of 0.5 cN to 2.0 cN, this tension level is insufficient to suppress the yarn's shrinkage behavior. Therefore, the PET component undergoes free thermal shrinkage relative to the polyethylene terephthalate (PET) component. Because the two components are distributed in a parallel or eccentric core-sheath pattern in cross-section, this asymmetrical shrinkage causes the yarn to generate bending torque, which in turn spontaneously forms a dense three-dimensional spiral crimp structure.

[0041] Next, step S50 will be explained in detail.

[0042] Step S50 involves rapid cooling and setting of the yarn after it leaves the texturing chamber. After exiting the texturing chamber, the yarn immediately passes through a water bath cooling device before entering the false twister. This water bath contains flowing water, with the water temperature constantly controlled between 20°C and 25°C. Utilizing the high thermal conductivity of water, the yarn undergoes a quenching effect upon contact with the water, rapidly reducing its temperature below its glass transition temperature. To ensure sufficient cooling, the cooling time in the water bath is maintained between 0.3 and 0.8 seconds by controlling the yarn's path length and speed in the water. This rapid cooling duration is sufficient to instantly fix the high-temperature spiral structure formed in step S40, preventing molecular chain relaxation. After leaving the water bath cooling device, a water film adheres to the yarn's surface. To prevent moisture from affecting the frictional performance of the subsequent false twister, an air nozzle is installed between the water bath outlet and the false twister inlet. When the yarn passes through the air nozzle, the high-pressure airflow blows away the water adhering to the surface of the yarn, allowing the yarn to enter the false twister in a dry state, thereby ensuring the stability of the false twisting process and the uniformity of twist transmission.

[0043] This invention relates to a method for preparing high-elastic polyester yarn. The yarn produced by this method exhibits strong structural stability, and its elastic recovery rate and bulkiness do not easily decrease even after high-temperature dyeing and washing processes. The method provided in this solution is based on a bicomponent parallel or eccentric core-sheath structure of polyethylene terephthalate (PET) and polybutylene terephthalate (PBT), with the temperature of the texturing chamber set between 240°C and 255°C. This temperature is close to the melting point of the PBT component. At this temperature, the PBT component softens upon heating, eliminating the internal stress generated during spinning and acquiring the ability to shrink. The key is to control the running tension of the yarn within the texturing chamber between 0.5 cN and 2.0 cN. In existing false-twist texturing processes, tensions of 15 cN or more are typically applied to prevent yarn vibration. This high tension straightens the yarn. When the yarn is straightened, even if the PBT component is heated, its shrinkage is inhibited by external forces and cannot proceed fully. Therefore, existing processes primarily rely on mechanical torsional forces to generate yarn crimp, leaving residual stress within the yarn. This mechanically formed crimp tends to straighten upon subsequent heating. This solution utilizes low tension to alleviate yarn shrinkage, causing the PBT component to shrink relative to the PET component at high temperatures. Since the two components are arranged side-by-side or eccentrically in cross-section, the shrinkage of the PBT component causes the yarn to bend, forming a helical structure. Because this helical structure is generated by the material's own shrinkage difference, rather than by external mechanical torsion, its structural stability is better. It should be noted that although this solution uses a low tension range, this tension limits and causes yarn vibration during operation. This is because at high temperatures of 240℃ to 255℃, the PBT component undergoes severe thermal shrinkage. This severe shrinkage consumes the relaxation provided by the low-tension feed, resulting in an internal shrinkage force driven by thermal shrinkage within the heating chamber. This internal shrinkage force maintains tension within the yarn, thus counteracting the relaxation effect of the external low tension and preventing yarn vibration within the heating chamber. Building upon this, this method further cools the yarn using a water bath at 20°C to 25°C after it leaves the heating chamber and before it enters the false twister. Existing processes typically employ natural air cooling or metal plate contact cooling, which results in relatively slow cooling rates. Since this method sets the heating temperature at 240°C to 255°C, the yarn is in a softened state upon leaving the heating chamber. If the cooling rate is too slow, the polymer chain segments will loosen and rearrange, causing the helical structure already formed in the heating zone to loosen or straighten. This method utilizes the thermal conductivity of water to rapidly cool the yarn, lowering its temperature below its glass transition temperature within a short time. This rapid cooling fixes the helical shape formed under high temperature and low tension, preventing structural loosening. Therefore, the yarn prepared by the method provided in this scheme has a stable helical crimp structure.During subsequent fabric dyeing, finishing, or washing processes, the yarn's crimped structure is less likely to disintegrate due to stress release, thus maintaining a high elastic recovery rate.

[0044] To further illustrate the properties of the polyester yarn obtained by the method for preparing high-elastic polyester yarn involved in this invention, the following examples and comparative examples are provided.

[0045] Example 1 Polyethylene terephthalate (PET) chips with an intrinsic viscosity of 0.66 dl / g and polybutylene terephthalate (PBT) chips with an intrinsic viscosity of 0.65 dl / g were selected. Both types of chips were vacuum dried at 85°C until the moisture content was below 50 PPM. After drying, the PET component was melt-extruded at 205°C, and the PBT component was melt-extruded at 215°C. The two melt streams entered a non-coated parallel composite spinning assembly, controlling the PET to PBT mass ratio at 70:30. The extruded melt streams were cooled by side-blowing air, oiled, and then wound at a speed of 1200 m / min to obtain 130 dtex parallel bicomponent pre-oriented yarn. The pre-oriented yarn was fed into a modified false-twist texturing machine. During the texturing process, the temperature of the texturing chamber was set to 250°C. By adjusting the speed ratio of the feed roller to the intermediate roller, the severe shrinkage of the PBT component at high temperatures is compensated, and the running tension of the yarn in the texturing chamber is precisely controlled at 1.0 cN. Under these conditions, the yarn is in a slightly relaxed state within the chamber, allowing the PBT component to undergo sufficient thermal shrinkage and causing the PET component to form a spiral curl. After leaving the texturing chamber, the yarn immediately enters a water bath cooling device, with the water temperature controlled at 22°C, and the yarn's residence time in the water is approximately 0.5 seconds. After leaving the water bath, the yarn passes through air nozzles to remove surface water. The dried yarn then enters a false twister, with the false twister speed set at 95,000 rpm. Finally, the yarn is wound at a speed of 600 m / min, with the winding tension controlled at 1.0 cN, yielding a 75D / 36F high-elastic polyester yarn.

[0046] Example 2 Polyethylene terephthalate (PET) chips with an intrinsic viscosity of 0.66 dl / g and polybutylene terephthalate (PBT) chips with an intrinsic viscosity of 0.65 dl / g were selected. Both types of chips were vacuum dried at 80°C until the moisture content was below 50 PPM. After drying, the PET component and the PBT component were melt-extruded at 190°C. The two melt streams entered a non-coated parallel composite spinning assembly, controlling the PET to PBT mass ratio at 70:30. The extruded melt streams were cooled by side-blowing air, oiled, and then wound at a speed of 800 m / min to obtain 130 dtex parallel bicomponent pre-oriented yarn. The pre-oriented yarn was fed into a modified false-twist texturing machine. During the texturing process, the temperature of the texturing chamber was set to 240°C. By adjusting the speed ratio of the feed roller to the intermediate roller, the severe shrinkage of the PBT component at high temperatures is compensated, and the running tension of the yarn in the texturing chamber is precisely controlled at 0.5 cN. Under these conditions, the yarn is in a slightly relaxed state within the chamber, allowing the PBT component to undergo sufficient thermal shrinkage and causing the PET component to form a spiral curl. After leaving the texturing chamber, the yarn immediately enters a water bath cooling device, with the water temperature controlled at 20°C, and the yarn's residence time in the water is approximately 0.3 seconds. After leaving the water bath, the yarn passes through air nozzles to remove surface water. The dried yarn then enters a false twister, with the false twister speed set at 80,000 rpm. Finally, the yarn is wound at a speed of 500 m / min, with the winding tension controlled at 0.5 cN, yielding a 75D / 36F high-elastic polyester yarn.

[0047] Example 3 Polyethylene terephthalate (PET) chips with an intrinsic viscosity of 0.66 dl / g and polybutylene terephthalate (PBT) chips with an intrinsic viscosity of 0.65 dl / g were selected. Both types of chips were vacuum dried at 90°C until the moisture content was below 50 PPM. After drying, the PET component was melt-extruded at 210°C, and the PBT component was melt-extruded at 220°C. The two melt streams entered a non-coated parallel composite spinning assembly, controlling the PET to PBT mass ratio at 70:30. The extruded melt streams were cooled by side-blowing air, oiled, and then wound at a speed of 1500 m / min to obtain 130 dtex parallel bicomponent pre-oriented yarn. The pre-oriented yarn was fed into a modified false-twist texturing machine. During the texturing process, the temperature of the texturing chamber was set to 255°C. By adjusting the speed ratio of the feed roller to the intermediate roller, the severe shrinkage of the PBT component at high temperatures is compensated, and the running tension of the yarn in the texturing chamber is precisely controlled at 2.0 cN. Under these conditions, the yarn is in a slightly relaxed state within the chamber, allowing the PBT component to undergo sufficient thermal shrinkage and causing the PET component to form a spiral curl. After leaving the texturing chamber, the yarn immediately enters a water bath cooling device, with the water temperature controlled at 25°C, and the yarn's residence time in the water is approximately 0.8 seconds. After leaving the water bath, the yarn passes through air nozzles to remove surface water. The dried yarn then enters a false twister, with the false twister speed set at 100,000 rpm. Finally, the yarn is wound at a speed of 800 m / min, with the winding tension controlled at 1.5 cN, yielding a 75D / 36F high-elastic polyester yarn.

[0048] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that, after obtaining the pre-oriented yarn, the pre-oriented yarn was fed into a conventional false-twist texturing machine, and the temperature of the texturing chamber was set to 210°C. The running tension of the yarn in the texturing chamber was controlled at 18.0 cN. After leaving the texturing chamber, the yarn was naturally cooled in air and passed through a false twister, the speed of which was set to 95,000 rpm. Finally, the yarn was wound at a speed of 600 m / min to obtain the comparative polyester yarn.

[0049] The yarns and fabrics obtained in Examples 1 to 3 and Comparative Example 1 were subjected to performance tests. The specific test methods and standards are as follows: Air permeability test: The test shall be conducted in accordance with GB / T 5453-1997 "Determination of air permeability of textile fabrics".

[0050] Boiling water shrinkage rate test: The test was conducted in accordance with GB / T 6505-2017 "Test method for heat shrinkage rate of chemical fiber filament (after treatment)".

[0051] Dimensional stability test: The test was conducted in accordance with GB / T 8630-2013 "Determination of dimensional changes of textiles after washing and drying".

[0052] Strength recovery rate and conventional physical properties: Tested in accordance with FZ / T 50004-2011 "Polyester Elastic Yarn" and related industry standards.

[0053] The test results are as follows:

[0054] See also Figure 1 and Figure 2 The figures show schematic diagrams of the polyester yarns provided in Example 1 and Comparative Example 1, respectively. Based on the above results and figures, it is clear that the yarns obtained in Examples 1, 2, and 3 are significantly superior to Comparative Example 1 in all key performance indicators. First, regarding elastic recovery performance, the yarns in the three examples maintain a high elastic recovery rate of approximately 80%, specifically 80.43%, 81.50%, and 79.80%, respectively, while Comparative Example 1, using conventional processes, only achieves 39.88%. This indicates that the polyester yarns prepared by the method provided by this invention have excellent elastic recovery rates. Second, regarding structural and dimensional stability, the boiling water shrinkage rates of the three examples are all controlled within a low range of 2.50% to 3.10%, and the warp and weft dimensional change rates of the fabrics are significantly better than those of Comparative Example 1.

[0055] The foregoing description of the specifications and embodiments is intended to explain the scope of protection of this invention, but does not constitute a limitation on the scope of protection of this invention. Modifications, equivalent substitutions, or other improvements to the embodiments of this invention or a portion thereof that can be obtained by those skilled in the art through logical analysis, reasoning, or limited experimentation, based on the teachings of this invention or the foregoing embodiments, in conjunction with common knowledge, general technical knowledge, and / or existing technology, should all be included within the scope of protection of this invention.

Claims

1. A process for the production of a high-elasticity polyester yarn, characterized by, Comprising the following steps: S10: providing a pre-oriented yarn composed of a polyethylene terephthalate component and a polybutylene terephthalate component, and the polyethylene terephthalate component and the polybutylene terephthalate component are distributed in a side-by-side type or eccentric core-sheath type in cross section; S20: feeding the pre-oriented yarn into a false twist texturing machine; S30: passing the yarn through a texturing hot box of the false twist texturing machine, the temperature of the texturing hot box is set to 240-255℃; S40: controlling the running tension of the yarn in the texturing hot box to be 0.5-2.0 cN by adjusting the speed ratio of feeding and output, so that the polybutylene terephthalate component is heat-shrunk and curled relative to the polyethylene terephthalate component; S50: after the yarn leaves the texturing hot box and before entering the false twister, passing the yarn through a water bath cooling device for cooling, the water temperature of the water bath cooling device is 20-25℃.

2. A process for the production of a high-elasticity polyester yarn as claimed in claim 1, characterized in that, In step S10, the intrinsic viscosity of the polyethylene terephthalate component is 0.66 dl / g, and the intrinsic viscosity of the polybutylene terephthalate component is 0.65 dl / g.

3. The method for preparing a high-elastic polyester yarn as described in claim 1, characterized in that, In step S10, the mass ratio of the polyethylene terephthalate component to the polybutylene terephthalate component is 1:(0.3-1); and the two components converge at the spinneret or the micropore outlet to form a non-coated side-by-side structure.

4. The method for preparing a high-elastic polyester yarn as described in claim 1, characterized in that, Further comprising step S05: before preparing the pre-oriented yarn, vacuum drying the polyethylene terephthalate chips and the polybutylene terephthalate chips respectively at a temperature of 80-90℃, so that the moisture content is less than 50 PPM.

5. The method for preparing a high-elastic polyester yarn as described in claim 1, characterized in that, The preparation process of the pre-oriented yarn in step S10 comprises: melt extruding the polyethylene terephthalate component at a temperature of 190-210℃, melt extruding the polybutylene terephthalate component at a temperature of 190-220℃, and winding at a spinning speed of 800-1500 m / min.

6. The method for preparing a high-elastic polyester yarn as described in claim 1, characterized in that, In step S30, the residence time of the yarn in the texturing hot box is 0.1-0.5 seconds.

7. The method of claim 1, wherein the step of drawing the high-elasticity polyester yarn is performed at a temperature of 80°C to 100°C. In step S50, the cooling time of the yarn in the water bath cooling device is 0.3-0.8 seconds; and after the yarn leaves the water bath cooling device, the attached water on the surface of the yarn is removed by an air nozzle.

8. The method for preparing a high-elastic polyester yarn as described in claim 1, characterized in that, In step S40, the running tension is controlled by adjusting the speed ratio between the feed roller and the intermediate roller of the false twist texturing machine.

9. The method for preparing a high-elastic polyester yarn as described in claim 1, characterized in that, In step S20, the rotational speed of the false twister is set to 80,000-100,000 rpm.

10. The method for preparing a high-elastic polyester yarn as described in claim 1, characterized in that, Further comprising step S60: winding the yarn after the false twist texturing treatment, the winding speed is 500-800 m / min, and the winding tension is 0.5-1.5 cN.

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