Process for preparing soft super high elastic fdy fiber with improved air permeability

Abstract

This invention discloses a method for preparing soft, ultra-elastic FDY fiber with improved breathability, comprising the following steps: S1, PET, polyamide, and PTT are sliced ​​separately, then PET, polyamide, and a composite agent are melted at a mass ratio of 1:1:0.05-0.1 and extruded through a first spinneret, and then PTT is directly melted and extruded through a second spinneret; the composite agent is made of n-octyl phthalate, silicone oil, and carbon nanotubes; the first spinneret uses gourd-shaped spinneret holes, and the second spinneret uses hollow spinneret holes; S2, the fiber is then subjected to FDY process and relaxation heat treatment to obtain FDY fiber. This invention utilizes the difference in heat shrinkage properties of the two components through composite spinning of PET, polyamide, and PTT polymers in parallel composite spinning to produce a durable, stable, and elastic crimp in the fiber, which helps to improve fiber properties such as looseness, strength, and elasticity.

Description

Technical Field

[0001] This invention relates to the field of FDY fiber technology, and specifically to a method for preparing soft, ultra-elastic FDY fiber with improved breathability. Background Technology

[0002] FDY fiber, short for fully drawn yarn, is a synthetic fiber incorporating stretching during the spinning process. This fiber is characterized by high orientation and moderate crystallinity, giving it a smooth and soft feel, making it commonly used in weaving imitation silk fabrics. Due to its excellent properties, FDY fiber has wide applications in the textile industry. However, with technological advancements, researchers are constantly exploring new methods to further improve the performance of FDY fiber or reduce its cost. The FDY production process is a complex and crucial spinning process. By carefully controlling key parameters such as temperature and stretch ratio, and strengthening quality control, high-quality FDY yarn can be produced to meet diverse needs while simultaneously prioritizing environmental protection and achieving sustainable development.

[0003] Fibers made from different polymer raw materials have completely different properties, each with its own advantages and disadvantages. Therefore, combining different fiber properties to create products leverages their respective strengths. Among these, side-by-side bicomponent composite fibers utilize the difference in heat shrinkage properties between the two components to cause the fiber to bend off-axis, exhibiting a permanent spiral curl. This curl is characterized by durability, stability, and good elasticity, giving fabrics better elasticity, bulkiness, and coverage, and is widely used in clothing. However, polyester bicomponent composite fibers have high requirements for their manufacturing process, mainly due to the need to control the flow state of the polymer melt in the spinneret. Because polyester bicomponent composite fibers are widely used in various skin-friendly fabrics, further improvements in their breathability and softness are needed. Summary of the Invention

[0004] To address the above problems, this invention provides a method for preparing soft, ultra-elastic FDY fibers with improved breathability.

[0005] The technical solution of this invention is: a method for preparing soft, ultra-elastic FDY fiber with improved breathability, comprising the following steps:

[0006] S1. Cut PET, polyamide, and PTT into slices. Then melt PET, polyamide, and composite agent in a mass ratio of 1:1:0.05 to 0.1 and extrude them through the first spinneret. Then melt PTT directly and extrude it through the second spinneret. The mass ratio of PET to PTT is 3:1 to 2.

[0007] The composite agent is made of n-octyl phthalate, silicone oil, and carbon nanotubes; the first spinneret has gourd-shaped spinneret holes, and the second spinneret has hollow spinneret holes.

[0008] The number of gourd-shaped spinnerets is a, and the number of hollow spinnerets is b, where a:b is 3-4:8-9; the diameters of the gourd-shaped spinnerets are d1 and d2, and the diameter of the hollow spinnerets is d3, where d1 = 1.6-1.7d2 and d3 = d2;

[0009] S2. After extrusion using the first spinneret and the second spinneret, fiber filaments are obtained. The fiber filaments are then spun in a parallel composite manner to form a single fiber filament. After cooling by a ring blower, the temperature of the ring blower is 20-30℃ and the wind speed is 0.5-1.4m / s. The fiber then undergoes FDY process and relaxation heat treatment to obtain FDY fiber.

[0010] Explanation: By using the above method to composite spin-spin PET, polyamide, and PTT polymers, the different properties of these fibers can be combined to create products that leverage their respective advantages. Parallel composite spinning utilizes the difference in heat shrinkage properties between the two components to produce fibers with durable, stable, and elastic crimp, giving the fabric better elasticity, fluffiness, and coverage. The difference between gourd-shaped and hollow spinnerets helps to improve fiber properties: increasing fiber strength, elongation, elasticity, and other mechanical properties. The relative number of spinnerets allows for an optimal ratio of extruded fibers from gourd-shaped and hollow spinnerets. The air velocity setting ensures a uniform fiber structure and avoids fusion; however, excessive air velocity may lead to uneven fiber structure, rough surface, or breakage.

[0011] Furthermore, the length-to-diameter ratio of the gourd-shaped spinneret is 2 to 3, and the diameter in the length-to-diameter ratio is d1.

[0012] Note: Further setting the aspect ratio of the gourd-shaped spinneret can improve fiber performance and further optimize fiber structure.

[0013] Furthermore, d2 is 0.15–0.3 mm.

[0014] Furthermore, in the FDY process, the FDY pre-network pressure is 0.05–0.2 MPa, and the speed parameters are: first roller speed is 2200–2280 m / min, second roller speed is 3000–3200 m / min, and winding speed is 2900–3000 m / min.

[0015] Furthermore, in the FDY process, the temperature parameters are: spinning temperature of 272-275℃, first roller temperature of 82-89℃, and second roller temperature of 140-145℃.

[0016] Note: By limiting the FDY process parameters as described above, the quality of the obtained FDY fiber products can be guaranteed. By controlling parameters such as temperature, running speed, spinneret diameter, draw ratio, and network pressure, FDY fibers can have stable performance indicators, such as strength and elongation at break, thereby improving production efficiency.

[0017] Furthermore, the relaxation heat treatment method is as follows:

[0018] First, a composite gas is introduced into the relaxation heat treatment equipment, and infrared heating is used to raise the temperature to 90-95℃. The first static treatment is carried out for 5-8 minutes. Then, the temperature is raised to 100-105℃ and the second static treatment is carried out for 3-4 minutes. Then, the temperature is raised to 110-115℃ and the third static treatment is carried out for 3-4 minutes. The treatment is then completed.

[0019] The composite gas is N2 and CO2 in a mass ratio of 1:1.

[0020] Explanation: By setting the relaxation heat treatment method described above, the fiber structure can be made looser, thereby improving the fiber's hand feel, making it softer and more comfortable, and significantly improving the hand feel of the fabric obtained from the fiber; at the same time, it increases the bulkiness: relaxation heat treatment can cause the fiber to undergo a certain degree of uneven shrinkage under humid heat, which improves the thermal stability of the fiber after it is further processed into fabric and makes it less prone to deformation; it also helps to improve the fiber's elasticity and other properties.

[0021] Further, the first settling treatment is as follows: 30% volume fraction of water vapor is introduced into the relaxation heat treatment equipment, while the pressure is adjusted to 0.16-0.18 MPa; the second settling treatment is as follows: 10% volume fraction of water vapor is introduced into the relaxation heat treatment equipment, while the pressure is adjusted to 0.20-0.22 MPa; the third settling treatment is as follows: the pressure is adjusted to 0.16-0.18 MPa.

[0022] Note: The above-mentioned further processing can enhance the effect of relaxation heat treatment. By applying pressure and adding moisture, the uneven shrinkage effect and thermal stability can be enhanced, thereby improving the elasticity of the fiber.

[0023] Furthermore, the preparation method of the composite agent is as follows:

[0024] S1-1. First, the carbon nanotubes are pretreated. The pretreatment method is as follows: the carbon nanotubes are mixed with 70% concentrated nitric acid at a ratio of 1g:1ml and soaked at 60-70℃ for 2-3h; then the carbon nanotubes are rinsed with deionized water and dried at 60℃ for 4-5h; the pretreated carbon nanotubes are obtained.

[0025] S1-2. Prepare octyl phthalate, silicone oil and pretreated carbon nanotubes in a mass ratio of 3:1 to 2:1. Then mix them using a microfluidic device for 10 to 20 minutes to obtain a composite agent. The frequency of the microfluidic device is 100 to 150 times / s and the working pressure of the microfluidic device is 300 to 350 MPa.

[0026] Note: The addition of the above-mentioned composite agents can improve the performance of FDY fibers in multiple ways, enhancing their usability. Octyl phthalate improves the plasticity of FDY fibers, making them easier to handle during processing. It also improves the fiber's hand feel, making it softer and more comfortable, and enhances dyeing performance. Silicone oil effectively reduces friction and wear during processing, improves fiber luster, enhances antistatic properties, and makes the fiber more stable during processing and use. Carbon nanotubes improve the fiber's mechanical properties and thermal stability.

[0027] Further, in step S1-1, after soaking for 2-3 hours, the carbon nanotubes are subjected to a first plasma treatment in a plasma atmosphere. The first plasma treatment power is 400-500W and the time is 3-10s. After rinsing with deionized water, the carbon nanotubes are subjected to a second plasma treatment in a plasma atmosphere. The second plasma treatment power is 600-650W and the time is 2-3s. The plasma is argon gas.

[0028] Note: The above method can enhance the surface properties of carbon nanotubes, thereby improving their dispersibility, ensuring uniform dispersion in the system, and improving the performance of FDY fibers.

[0029] The beneficial effects of this invention are:

[0030] (1) This invention uses composite spinning of three polymers, PET, polyamide and PTT, to combine the different properties of the above fibers to make products, giving full play to their respective advantages. Parallel composite spinning utilizes the difference in heat shrinkage properties of the two components to make the fibers produce a durable, stable and elastic crimp, giving the fabric better elasticity, fluffiness and coverage. By setting the gourd-shaped spinneret and the hollow spinneret, it can help improve the fiber properties: improve the strength, elongation and elasticity of the fiber mechanical properties; by setting the relative number of spinnerets, the ratio of extruded yarn from the gourd-shaped spinneret and the hollow spinneret can be optimized; the wind speed setting can make the fiber structure uniform and avoid the melting phenomenon; while if the wind speed exceeds the range, it may lead to uneven fiber structure or surface roughness or breakage.

[0031] (2) The relaxation heat treatment setting of this invention can make the fiber structure more loose, thereby improving the fiber's hand feel, making it softer and more comfortable, and significantly improving the hand feel of the fabric obtained from the fiber; at the same time, it increases the bulkiness: relaxation heat treatment can cause the fiber to produce a certain degree of uneven shrinkage under humid heat, so that the fiber can improve thermal stability and is less prone to deformation after further processing into fabric; at the same time, it helps to improve the fiber's elasticity and other properties. Through the addition of composite agents, the performance of FDY fiber can be improved in many aspects, increasing the fiber's use value. Octyl phthalate can improve the plasticity of FDY fiber, making it easier to handle during processing. At the same time, it can also improve the fiber's hand feel, making it softer and more comfortable, and improve dyeing performance. Silicone oil effectively reduces the friction and wear of the fiber during processing, improves the fiber's luster, and improves the fiber's antistatic properties, making the fiber more stable during processing and use; carbon nanotubes improve the fiber's mechanical properties and thermal stability. Attached Figure Description

[0032] Figure 1 This is a graph showing the influence of FDY process parameters on the breaking elongation and crimp stability of FDY fibers in this embodiment of the invention. Detailed Implementation

[0033] The present invention will now be described in more detail with reference to specific embodiments, so as to better demonstrate the advantages of the present invention.

[0034] Example 1:

[0035] A method for preparing a soft, ultra-elastic FDY fiber with improved breathability includes the following steps:

[0036] S1. Cut PET, polyamide, and PTT into slices. Then melt PET, polyamide, and composite agent in a mass ratio of 1:1:0.08 and extrude them through the first spinneret. Then melt PTT directly and extrude it through the second spinneret. The mass ratio of PET to PTT is 3:1.5.

[0037] The composite agent is made of n-octyl phthalate, silicone oil, and carbon nanotubes; the first spinneret has gourd-shaped spinneret holes, and the second spinneret has hollow spinneret holes.

[0038] The number of gourd-shaped spinnerets is 'a', and the number of hollow spinnerets is 'b', with a:b = 3:9. The diameters of the gourd-shaped spinnerets are d1 and d2, and the diameter of the hollow spinnerets is d3, where d1 = 1.6d2 and d3 = d2; d2 is 0.2 mm. The length-to-diameter ratio of the gourd-shaped spinnerets is 2, with the diameter in the length-to-diameter ratio being d1.

[0039] S2. After extrusion using the first spinneret and the second spinneret, fiber filaments are obtained. The fiber filaments are then spun in a parallel composite manner to form a single fiber filament. The fiber filaments are then cooled by a ring blower at a temperature of 205°C and a wind speed of 0.9 m / s. The fiber filaments are then subjected to the FDY process and relaxation heat treatment to obtain FDY fiber.

[0040] In the FDY process, the FDY pre-network pressure is 0.1 MPa, and the speed parameters are: the first roller speed is 2250 m / min, the second roller speed is 3100 m / min, and the winding speed is 2950 m / min.

[0041] The temperature parameters are as follows: spinning temperature is 273℃, first roller temperature is 85℃, and second roller temperature is 142℃.

[0042] The relaxation heat treatment method is as follows: First, a composite gas is introduced into the relaxation heat treatment equipment, and infrared heating is used to raise the temperature to 93°C. The temperature is then left to stand for 6 minutes. Next, the temperature is raised to 103°C and left to stand for 3 minutes. Then, the temperature is raised to 113°C and left to stand for 3 minutes. The treatment is then completed. The composite gas is N2 and CO2 with a mass ratio of 1:1.

[0043] Example 2: The difference between this example and Example 1 is that the raw material composition is different. PET, polyamide and PTT are sliced ​​separately, and then PET, polyamide and composite agent are melted in a mass ratio of 1:1:0.05. The mass ratio of PET:PTT is 3:1.

[0044] Example 3: The difference between this example and Example 1 is that the raw material composition is different. PET, polyamide and PTT are sliced ​​separately, and then PET, polyamide and composite agent are melted in a mass ratio of 1:1:0.1. The mass ratio of PET:PTT is 3:2.

[0045] Example 4: The difference between this example and Example 1 is that the number of spinnerets in the first spinneret and the second spinneret is different, with a:b being 4:8.

[0046] Example 5: The difference between this example and Example 1 is that the number of spinnerets in the first spinneret and the second spinneret is different, with a:b being 4:9.

[0047] Example 6: This example differs from Example 1 in that the spinneret orifice sizes are different. The gourd-shaped spinneret orifices have diameters of d1 and d2, while the hollow spinneret orifice has a diameter of d3, with d1 = 1.7d2 and d2 being 0.3 mm. The length-to-diameter ratio of the gourd-shaped spinneret orifice is 3.

[0048] Example 7: This example differs from Example 1 in that the spinneret orifice sizes are different. The diameters of the gourd-shaped spinnerets are d1 and d2, and the diameter of the hollow spinneret is d3, with d1 = 1.7d2 and d2 being 0.15 mm. The length-to-diameter ratio of the gourd-shaped spinnerets is 2.

[0049] Example 8: This example differs from Example 1 in that the FDY process parameters are different. The FDY pre-network pressure is 0.05MPa, and the speed parameters are: the speed of the first roller is 2280m / min, the speed of the second roller is 3200m / min, and the winding speed is 2900m / min; the temperature of the ring blower is 20℃, and the wind speed is 0.5m / s.

[0050] Example 9: This example differs from Example 1 in that the FDY process parameters are different. The FDY pre-network pressure is 0.2MPa, and the speed parameters are: the speed of the first roller is 2200m / min, the speed of the second roller is 3000m / min, and the winding speed is 3000m / min; the temperature of the ring blower is 30℃, and the wind speed is 1.4m / s.

[0051] Example 10: This example differs from Example 1 in that the FDY temperature parameters are different. The spinning temperature is 272°C, the first roller temperature is 82°C, and the second roller temperature is 140°C.

[0052] Example 11: This example differs from Example 1 in that the FDY temperature parameters are different. The spinning temperature is 275°C, the first roller temperature is 89°C, and the second roller temperature is 145°C.

[0053] Example 12: This example differs from Example 1 in that the relaxation heat treatment parameters are different. The temperature is raised to 95°C and left to stand for 8 minutes. Then the temperature is raised to 105°C and left to stand for 3 minutes. Then the temperature is raised to 110°C and left to stand for 4 minutes. The treatment is then completed.

[0054] Example 13: This example differs from Example 1 in that the relaxation heat treatment parameters are different. The temperature is raised to 90°C and left to stand for 5 minutes. Then the temperature is raised to 100°C and left to stand for 4 minutes. Then the temperature is raised to 115°C and left to stand for 3 minutes. The treatment is then completed.

[0055] Example 14: This example differs from Example 1 in that the first settling process is: 30% volume fraction of water vapor is introduced into the relaxation heat treatment equipment, while the pressure is adjusted to 0.167 MPa; the second settling process is: 10% volume fraction of water vapor is introduced into the relaxation heat treatment equipment, while the pressure is adjusted to 0.21 MPa; the third settling process is: the pressure is adjusted to 0.17 MPa.

[0056] Example 15: This example differs from Example 14 in that the static treatment parameters are different. The pressure is adjusted to 0.16 MPa for the first static treatment; 0.22 MPa for the second static treatment; and 0.18 MPa for the third static treatment.

[0057] Example 16: The difference between this example and Example 14 is that the static treatment parameters are different. The pressure is adjusted to 0.18 MPa for the first static treatment; 0.20 MPa for the second static treatment; and 0.16 MPa for the third static treatment.

[0058] Example 17: This example differs from Example 14 in that the preparation method of the composite agent is as follows:

[0059] S1-1. First, the carbon nanotubes are pretreated by mixing carbon nanotubes with 70% concentrated nitric acid at a ratio of 1g:1ml and soaking at 65°C for 2.5h; then the carbon nanotubes are rinsed with deionized water and dried at 60°C for 4.5h; the pretreated carbon nanotubes are obtained.

[0060] S1-2. Prepare octyl phthalate, silicone oil and pretreated carbon nanotubes in a mass ratio of 3:1.5:1. Then mix them for 15 minutes using a microfluidic device to obtain a composite agent. The frequency of the microfluidic device is 125 times / s and the working pressure of the microfluidic device is 325 MPa. The microfluidic device uses the NanoGenizer microfluidic high-pressure homogenizer, which is a technology currently available.

[0061] Example 18: This example differs from Example 17 in that, in S1-1, the carbon nanotubes are soaked at 60°C for 3 hours; then rinsed with deionized water and dried at 60°C for 5 hours to obtain pretreated carbon nanotubes; in S1-2, octyl phthalate, silicone oil and pretreated carbon nanotubes are prepared in a mass ratio of 3:2:1, and then mixed using a microfluidic device for 20 minutes to obtain a composite agent. The frequency of the microfluidic device is 150 times / s and the working pressure of the microfluidic device is 350 MPa.

[0062] Example 19: This example differs from Example 17 in that, in S1-1, the carbon nanotubes are soaked at 70°C for 2 hours; then rinsed with deionized water and dried at 60°C for 4 hours to obtain pretreated carbon nanotubes; in S1-2, octyl phthalate, silicone oil and pretreated carbon nanotubes are prepared in a mass ratio of 3:1:1, and then mixed using a microfluidic device for 10 minutes to obtain a composite agent. The frequency of the microfluidic device is 100 times / s and the working pressure of the microfluidic device is 300 MPa.

[0063] Example 20: This example differs from Example 17 in that, after soaking for 2.5 hours, the carbon nanotubes are subjected to a first plasma treatment in a plasma atmosphere. The first plasma treatment power is 450W and the time is 8 seconds. After rinsing with deionized water, the carbon nanotubes are subjected to a second plasma treatment in a plasma atmosphere. The second plasma treatment power is 625W and the time is 2 seconds. The plasma is argon gas.

[0064] Example 21: This example differs from Example 20 in that the primary plasma treatment power is 400W and the time is 10s. After rinsing with deionized water, the carbon nanotubes are subjected to a secondary plasma treatment in a plasma atmosphere. The secondary plasma treatment power is 650W and the time is 3s.

[0065] Example 22: This example differs from Example 20 in that the primary plasma treatment power is 500W and the time is 3s. After rinsing with deionized water, the carbon nanotubes are subjected to a secondary plasma treatment in a plasma atmosphere. The secondary plasma treatment power is 600W and the time is 2s.

[0066] Experimental Example: Performance tests were conducted on the FDY fibers obtained in Examples 1 to 22. The test results are as follows:

[0067] The FDY fiber obtained in Example 1 has a water absorption rate of up to 1.5%;

[0068] like Figure 1 As shown in the figure, the crimp stability and elongation at break of the FDY fibers obtained in Examples 1 to 22 are respectively represented by the data in the figure.

[0069] The performance parameters of the FDY fibers obtained in Examples 1 to 22 are as follows: breaking elongation 50-60%; breaking strength 5-8.0 cN / dtex; monofilament fineness 0.5-1.5 dtex; crimp stability 80-85%.

[0070] Fibers with higher breaking elongation have a softer hand feel and can cushion the force during textile processing, reducing fuzz and breakage; fibers with higher breaking strength have a stronger load-bearing capacity and can withstand greater external forces without breaking; fibers with smaller monofilament fineness are generally softer and more comfortable to the touch; fibers with higher crimp stability usually have better elasticity and a softer hand feel; improving crimp stability and breaking elongation can significantly improve the breathability of fiber fabrics;

[0071] Comparative Example 1: The difference from Example 1 is that PET was used as the raw material;

[0072] Comparative Example 2: The difference from Example 1 is that both the first spinneret and the second spinneret use conventional circular spinneret holes;

[0073] Comparative Example 3: The difference from Example 1 is that the relaxation heat treatment method is: constant temperature at 95°C for 20 minutes;

[0074] Comparative Example 4: Unlike Example 1, no composite agent was added;

[0075] 1. Investigate the effects of different preparation methods on the properties of the obtained FDY fibers;

[0076] Example 1 and Comparative Examples 1 to 4 were compared, as shown in Table 1;

[0077] Table 1. Effects of different preparation methods on the properties of the obtained FDY fibers

[0078]

[0079] As shown in Table 1,

[0080] Comparing Example 1 with Comparative Example 1, it can be seen that the composite spinning of PET, polyamide and PTT polymers as raw materials in Example 1 can produce a long-lasting, stable and elastic crimp effect in the fiber, thereby improving various properties.

[0081] Comparing Example 1 and Comparative Example 2, it can be found that the conventional spinneret used in Example 1 helps to improve the fiber properties, resulting in fibers with better mechanical properties such as strength, elongation, and elasticity.

[0082] Comparing Example 1 and Comparative Example 3, it can be found that the relaxation heat treatment method in Example 1 is more preferred. The relaxation heat treatment in Example 1, which involves filling with composite gas and setting a temperature gradient, can further improve fiber properties and increase stability.

[0083] Comparing Example 1 with Comparative Example 4, it can be found that the addition of the composite agent in Example 1 can significantly improve the breaking elongation and crimp stability, thereby improving the hand feel of the fiber.

[0084] 2. Investigate the effects of different FDY process parameters on the properties of the obtained FDY fibers;

[0085] like Figure 1 As shown, among Examples 1 to 13, the parameters of Example 1 are preferred; parameters such as temperature, running speed, spinneret diameter, draw ratio and network pressure can enable FDY fibers to have stable performance indicators, such as strength and elongation at break. The parameters of Example 1 are more suitable, while the performance results of the other examples are slightly reduced.

[0086] 3. Investigate the effects of different heat relaxation treatment parameters on the properties of the obtained FDY fibers;

[0087] Comparative Example 5: Unlike Example 1, in the relaxation heat treatment, the pressure was not adjusted during the first, second, and third settling treatments; specifically, the first settling treatment was: 30% volume fraction of water vapor was introduced into the relaxation heat treatment equipment; the second settling treatment was: 10% volume fraction of water vapor was introduced into the relaxation heat treatment equipment; and the third settling treatment was a settling treatment.

[0088] Examples 14 to 16 and Comparative Example 5 were compared, as shown in Table 2.

[0089] Table 2 Effects of different heat relaxation treatments on the properties of the obtained FDY fibers

[0090] parameter Elongation at break % Fracture strength cN / dtex Monofilament fineness dtex Example 1 55 6.9 0.9 Example 14 59 7.5 0.7 Example 15 58 7.2 0.9 Example 16 57 7.3 0.8 Comparative Example 5 55 7.1 0.9

[0091] As can be seen from Table 2,

[0092] Comparing Example 1 and Example 14, it can be seen that the FDY fiber parameters obtained in Example 14 are better, with improved breaking elongation and breaking strength, and reduced single filament fineness to increase softness. It can be seen that the traditional relaxation heat treatment and the adjustment of water vapor and pressure in Example 14 can improve the elasticity and softness properties of the fiber.

[0093] Comparing Example 14 with Comparative Example 5, it can be seen that the relaxation heat treatment method of Example 14 has a better effect, that is, pressure adjustment is necessary.

[0094] Comparing Examples 14 to 16, it can be seen that the parameters of Example 14 are more preferred.

Claims

1. A method for preparing a soft super high elastic -FDY fiber for improving air permeability, characterized by, Includes the following steps: S1. Cut PET, polyamide, and PTT into slices. Then melt PET, polyamide, and composite agent in a mass ratio of 1:1:0.05~0.1 and extrude them through the first spinneret. Then melt PTT directly and extrude it through the second spinneret. The mass ratio of PET:PTT is 3:1~2. The composite agent is made of n-octyl phthalate, silicone oil, and carbon nanotubes; the preparation method of the composite agent is as follows: S1-1. First, carbon nanotubes are pretreated. The pretreatment method is as follows: carbon nanotubes are mixed with 70% mass fraction concentrated nitric acid at a ratio of 1g:1ml, and soaked at 60~70℃ for 2~3h; then the carbon nanotubes are rinsed with deionized water and dried at 60℃ for 4~5h; the pretreated carbon nanotubes are obtained. S1-2. Prepare octyl phthalate, silicone oil and pretreated carbon nanotubes in a mass ratio of 3:1 to 2:1, and then mix them for 10 to 20 minutes using a microfluidic apparatus to obtain a composite agent. The frequency of the microfluidic apparatus is 100 to 150 times / s and the working pressure of the microfluidic apparatus is 300 to 350 MPa. The first spinneret has gourd-shaped spinneret holes, and the second spinneret has hollow spinneret holes; The number of gourd-shaped spinnerets is a, and the number of hollow spinnerets is b, where a:b is 3~4:8~9; the diameters of the gourd-shaped spinnerets are d1 and d2, and the diameter of the hollow spinnerets is d3, where d1=1.6~1.7d2 and d3=d2; S2. After extrusion using the first spinneret and the second spinneret, fiber filaments are obtained. The fiber filaments are then spun in a parallel composite manner to form a single fiber filament. The fiber filaments are then cooled by a ring blower with a temperature of 20~30℃ and a wind speed of 0.5~1.4m / s. The fiber filaments are then subjected to the FDY process and relaxation heat treatment to obtain FDY fibers. The relaxation heat treatment method is as follows: First, a composite gas is introduced into the relaxation heat treatment equipment, and infrared heating is used to raise the temperature to 90~95℃. The first static treatment is carried out for 5~8 minutes. Then the temperature is raised to 100~105℃ and the second static treatment is carried out for 3~4 minutes. Then the temperature is raised to 110~115℃ and the third static treatment is carried out for 3~4 minutes. The treatment is then completed. The composite gas is N2 and CO2 in a mass ratio of 1:

1.

2. The process for preparing a soft super high elastic - FDY fiber with improved air permeability as claimed in claim 1 wherein, The length-to-diameter ratio of the gourd-shaped spinneret is 2 to 3, and the diameter in the length-to-diameter ratio is d1. ​ 3. The method for preparing a soft, ultra-elastic FDY fiber with improved breathability as described in claim 1, characterized in that, d2 is 0.15~0.3mm.

4. The method for preparing a soft, ultra-elastic FDY fiber with improved breathability as described in claim 1, characterized in that, In the FDY process, the FDY pre-network pressure is 0.05~0.2MPa, and the speed parameters are: first roller speed is 2200~2280m / min, second roller speed is 3000~3200m / min, and winding speed is 2900~3000m / min.

5. The method for preparing a soft, ultra-elastic FDY fiber with improved breathability as described in claim 1, characterized in that, In the FDY process, the temperature parameters are: spinning temperature 272~275℃, first roller temperature 82~89℃, and second roller temperature 140~145℃.

6. The method for preparing a soft, ultra-elastic FDY fiber with improved breathability as described in claim 5, characterized in that, The first settling process involves introducing 30% volume fraction water vapor into the relaxation heat treatment equipment while adjusting the pressure to 0.16~0.18 MPa; the second settling process involves introducing 10% volume fraction water vapor into the relaxation heat treatment equipment while adjusting the pressure to 0.20~0.22 MPa; and the third settling process involves adjusting the pressure to 0.16~0.18 MPa.

7. The method for preparing a soft, ultra-elastic FDY fiber with improved breathability as described in claim 6, characterized in that, In step S1-1, after soaking for 2-3 hours, the carbon nanotubes are subjected to a first plasma treatment in a plasma atmosphere. The first plasma treatment power is 400-500W and the time is 3-10 seconds. After rinsing with deionized water, the carbon nanotubes are subjected to a second plasma treatment in a plasma atmosphere. The second plasma treatment power is 600-650W and the time is 2-3 seconds. The plasma is argon gas.

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