Production method of polyester fine denier porous fiber veneer

Abstract

The invention belongs to the technical field of textile materials and processing, and relates to a polyester fine denier porous fiber veneer production method which comprises a spinning assembly spinning procedure and a cooling procedure, and first-stage circular air blowing cooling, second-stage circular air blowing cooling and side air blowing cooling are sequentially carried out during cooling; at the junction of the cross air blowing cooling area and the side air blowing cooling area, the hot air flowing downwards from the cross air blowing cooling area and influencing the side air blowing cooling effect is cooled, and downward movement of the hot air is stopped; and the specification of the polyester fine denier porous fiber is 368 to 580dtex / 548 to 576F. Cooling is carried out in three stages, parameters such as the circular blowing air pressure are reasonably set, the problems of doubling, broken filaments, broken ends, yarn unevenness increase and the like caused by improper circular blowing air pressure are solved, and the fiber quality problem is effectively reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of textile materials and processing, and relates to a single-plate production method for polyester fine denier porous fibers. Background Art

[0002] In the textile industry, polyester fibers, especially polyester fine denier porous fibers, are widely used due to their excellent physical properties. Fabrics made of such fibers are not only light but also have excellent air permeability, drapability and softness, making them the preferred materials for high-grade fabrics such as imitation silk and thin pile fabrics, showing good market prospects and significant economic benefits. Specifically, polyester fine denier porous fibers with a specification of 368-580 dtex / 548-576F play an important role in the manufacture of high-grade fabrics and many other fields.

[0003] However, in the process of producing such high-performance fibers, especially when pursuing an efficient and high-quality single-plate production method, a series of technical challenges are faced. Traditional multi-strand twisting production methods, as described in the patent application with publication number CN101078135A, although improve production efficiency to a certain extent, are prone to problems such as poor bundling of porous fibers and dispersion of tail filaments during the winding and twisting process, seriously affecting the passing rate of the subsequent texturing process and thus reducing the overall product quality.

[0004] To solve the above problems, a single-plate production method has emerged. This method directly produces through a single spinneret, which not only increases the unit output but also effectively improves the bundling of tail filaments. However, due to the large number of holes in polyester fine denier porous fibers, extremely high requirements are imposed on the cooling process. Existing cooling processes are inadequate when dealing with such high-hole-count fibers. The literature ("Discussion on the single-plate direct spinning process of high linear density fine denier polyester pre-oriented yarns" [J]. Advanced Textile Technology. 2013, (4): 1-3.) points out that when the ring blowing pressure is set small, the cooling air volume is insufficient to cool the filament bundle evenly and sufficiently, resulting in an increase in the unevenness rate of the filament bundle and an increase in the number of broken ends, seriously affecting the continuity and uniformity of the fibers; on the contrary, if the ring blowing pressure is increased, although the cooling speed can be accelerated, excessive cooling will cause the filament bundle to vibrate violently, increasing the risk of quality defects such as filament entanglement, which is also not conducive to improving the fiber quality.

[0005] Therefore, developing a cooling process that can effectively meet the requirements of single-plate production of polyester fine denier porous fibers is the key to improving the comprehensive performance of fibers, ensuring production efficiency and product quality. Summary of the Invention

[0006] The object of the present invention is to solve the problems existing in the prior art and provide a single-plate production method for polyester fine denier porous fibers.

[0007] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] A single-plate production method of polyester fine denier porous fiber, including a spinning process and a cooling process of a spinning component. During cooling, first-stage ring blowing cooling, second-stage ring blowing cooling and side blowing cooling are carried out in sequence;

[0009] During the first-stage ring blowing cooling, the ring blowing pressure is 25-28 Pa, and the length of the first ring blowing cylinder used is 10-12 cm;

[0010] During the second-stage ring blowing cooling, the ring blowing pressure is 32-35 Pa, and the length of the second ring blowing cylinder used is 8-14 cm;

[0011] The total length of the first ring blowing cylinder, the second ring blowing cylinder and the side blowing screen plate is 66-73 cm, and the side blowing wind speed is 0.60-0.70 m / s;

[0012] At the junction of the ring blowing cooling zone and the side blowing cooling zone, the hot air flowing out downward from the ring blowing cooling zone and affecting the side blowing cooling effect is cooled down and blocked from moving downward;

[0013] The specification of the polyester fine denier porous fiber is 368-580 dtex / 548-576 f.

[0014] Since the number of holes in the polyester fine denier porous fiber is relatively large, when the ring blowing pressure is small, the cooling air volume is insufficient and the filament bundle cannot be cooled evenly and sufficiently, resulting in an increase in the unevenness rate of the filament bundle and the number of broken ends; when the ring blowing pressure is large, the filament bundle cools quickly, the filament bundle oscillation intensifies, and problems such as filament doubling occur. To solve this problem, the present invention cools in three stages, namely first-stage ring blowing cooling, second-stage ring blowing cooling and side blowing cooling.

[0015] The first stage is the state before the melt stream is stretched and solidified. The fiber diameter decreases gradually from the maximum diameter in the windless zone (the expansion zone at the spinneret exit) until it is basically stable. In this stage, a slightly lower annular blowing pressure (25 - 28 Pa) can prevent the problem of fiber merging caused by excessive annular blowing pressure. Since this is the expansion zone and the stretching zone where the fiber is not fully solidified and is extremely vulnerable to the lateral force interference of the cooling air, and at this time the annular blowing pressure is small, the length of the first annular blowing cylinder is set to 10 - 12 cm in the present invention, which can match this special state area of the fiber, reduce interference, prevent fiber flutter, and problems such as fiber merging. When the annular blowing pressure is too high, due to the large number of fiber holes, the unfrozen fibers are impacted by the strong air flow, resulting in lateral flutter of the fibers, causing fiber merging, hairiness, and even breakage. When the annular blowing pressure is too low, the cooling efficiency is insufficient, the melt stream cannot be solidified in time, and the fiber is prone to breakage during subsequent drawing. If the length of the first annular blowing cylinder is too large or too small, the window effect of the wind pressure parameter will be amplified, making the abnormal situation more serious.

[0016] The second stage is still the state before the tow is solidified. If the annular blowing pressure is too low, the wind speed in the center of the annular blowing cylinder for polyester fine denier multi-hole fiber will be very low, the cooling effect will be poor, it is easy to generate a large radial temperature gradient difference in the cross-section of the filament, resulting in differences in the radial cross-section structure of the fiber, causing problems such as low breaking strength of the fiber, unevenness of the yarn evenness, and an increase in the number of broken ends. If the annular blowing pressure is too high, the adjacent single filaments will generate synchronous vibration, increasing the probability of fiber merging to 3 - 5 times that of the normal working condition. If the length of the second annular blowing cylinder is too large, the Bernoulli effect will be aggravated, increasing the impact frequency of the fiber by the lateral pulsating air flow and causing large amplitude jitter. If the length of the second annular blowing cylinder is too small, the action distance of the cooling air is short, resulting in an increase in the proportion of the residual melt in the fiber core layer, and further increasing the unevenness of the fiber yarn evenness.

[0017] Single annular blowing cooling will lead to abnormal cooling in sections similar to slub yarn due to the short cooling distance, resulting in an abnormal increase in the yarn evenness value of the product. In the present invention, side blowing cooling is carried out after the second annular blowing cooling. The cooling conditions of side blowing cooling are relatively intense (the side blowing wind speed is 0.60 - 0.70 m / s), which can quickly cool the tow. The total length of the first annular blowing cylinder, the second annular blowing cylinder, and the side blowing mesh plate is 66 - 73 cm, which can ensure uniform cooling of the fiber and good evenness of the fiber yarn. If the side blowing wind speed is too high, it is easy to form a skin-core structure. The high-speed air flow instantaneously vitrifies the fiber surface layer, forming a brittle skin layer (the breaking elongation rate of this part of the brittle skin layer decreases by 30 - 40%), and the melt flow in the core is blocked, resulting in internal stress cracks. If the side blowing wind speed is too low, insufficient cooling causes elastic retraction of the fiber during drawing, increasing the diameter fluctuation range and raising the unevenness of the finished fiber yarn. If the length of the side blowing mesh plate is too large or too small, the window effect of the wind speed parameter will be amplified, making the abnormal situation more serious.

[0018] In addition, since the polyester fine denier porous fiber has a relatively large number of pores and the temperature inside the second ring air blower is relatively high, when the tow leaves the second ring air blower, a large amount of hot air at a relatively high temperature will blow vertically downward. At the moment when the side air blower contacts the tow, the side air blower will be blocked by the hot air and heated up, which will result in a worse cooling effect of the filament strip the farther away from the air outlet end of the side air blower. Therefore, in the present invention, at the junction of the ring air blowing cooling zone and the side air blowing cooling zone, the hot air flowing downward from the ring air blowing cooling zone and affecting the cooling effect of the side air blower is cooled down and its downward movement is blocked, so as to ensure more uniform cooling when transitioning from ring air blowing to side air blowing.

[0019] As a preferred technical solution:

[0020] In a method for producing a single plate of polyester fine denier porous fiber as described above, the upper and lower sections of the first ring air blower and the second ring air blower are the upper and lower sections of the same ring air blower. The inner diameters of the first ring air blower and the second ring air blower are the same. The aperture of the mesh holes of the first ring air blower is 0.110 - 0.114 mm, and the aperture of the mesh holes of the second ring air blower is 0.220 - 0.228 mm.

[0021] In a method for producing a single plate of polyester fine denier porous fiber as described above, at the junction of the ring air blowing cooling zone and the side air blowing cooling zone, the implementation method for cooling down the hot air flowing downward from the ring air blowing cooling zone and affecting the cooling effect of the side air blower and blocking its downward movement is as follows:

[0022] Install 1 C-shaped plate at the lower end of the second ring air blower. The material of the C-shaped plate is an alloy, the thermal conductivity is 300 - 350 W / m·K, it is hollow inside and is connected to the circulating cooling water delivery pipeline;

[0023] The area between the tow and the second ring air blower is an annular area, which is composed of a symmetric first semi-annular area and a second semi-annular area. The symmetry axes of the two are parallel to the side blowing screen plate. The second semi-annular area is close to the side blowing screen plate, and the orthographic projection of the second semi-annular area completely coincides with the C-shaped plate.

[0024] In a method for producing a single plate of polyester fine denier porous fiber as described above, the lower end face of the second ring air blower is parallel to the horizontal plane, and the angle between the C-shaped plate and the horizontal plane is 30°. In this way, it can be avoided that the downward hot air affecting the cooling effect of the side air blower becomes too disordered after being affected by the C-shaped plate and has an adverse effect on the tow.

[0025] A single-plate production method of polyester fine denier porous fiber as described above, the second ring air blower is installed on the air blower frame, hinges are installed at the bottom of the air box, the axis of the hinges is horizontally arranged and parallel to the side blowing screen plate, one leaf of the hinges is fixedly connected to the bottom of the air box, and the other leaf of the hinges is fixedly connected to the position closest to the side blowing screen plate of the C-shaped plate and this leaf is connected to the bottom of the air box through a magnetic attraction device so that the included angle between the C-shaped plate and the horizontal plane is 30°. When restarting after stopping, the C-shaped plate is not needed. At this time, the magnetic attraction device is removed and the C-shaped plate is allowed to hang naturally under the action of gravity.

[0026] A single-plate production method of polyester fine denier porous fiber as described above, the temperature of the circulating cooling water conveyed by the circulating cooling water conveying pipeline is 23-25°C, and the flow rate is 0.08-0.1 L / min.

[0027] A single-plate production method of polyester fine denier porous fiber as described above, the overall process flow is: spinning by the spinning pack → cooling → spinning oiling → the first godet roller → pre-network → the second godet roller → winding and forming.

[0028] A single-plate production method of polyester fine denier porous fiber as described above, the diameter of the spinneret plate is 120 mm, the aperture of the spinneret hole is 0.14-0.16 mm, the length of the spinneret hole is 0.50-0.52 mm, the temperature of the spinning box is 287-289°C, the length of the windless area is 50-60 mm, the cooling air temperature is 20-22°C, the relative humidity of the cooling air is 75-85%, the bundling height is 850-950 mm, the speed of the first godet roller is 2680-2855 m / min, the speed of the second godet roller is 2685-2860 m / min, the pre-network pressure is 0.08-0.09 MPa, and the winding speed is 2665-2840 m / min.

[0029] A single-plate production method of polyester fine denier porous fiber as described above, the breaking strength of the polyester fine denier porous fiber ≥ 2.45 cN / dtex, the CV value of the breaking strength ≤ 3.09%, the breaking elongation is 124.1-126.9%, the CV value of the breaking elongation ≤ 2.81%, the unevenness rate of yarn evenness ≤ 1.24%, the number of broken ends ≤ 2.5 times / 18 positions·24 hours, the thermal stress deviation ≤ M×3%; M is the thermal stress central value, unit cN.

[0030] Beneficial effects:

[0031] The present invention conducts cooling in three stages (the first stage of ring air blowing cooling, the second stage of ring air blowing cooling and side air blowing cooling). By reasonably setting parameters such as the ring air blowing pressure, problems such as filament doubling, hairiness, broken ends, and increased unevenness rate of yarn evenness caused by improper ring air blowing pressure are avoided, and fiber quality problems are effectively reduced. Description of the drawings

[0032] Figure 1 Front view of the device for cooling a tow

[0033] Figure 2 Side view of the device for cooling a tow

[0034] Figure 3 Bottom view of the device for cooling a tow

[0035] Wherein, 1 - air box, 2 - first annular air blowing cylinder, 3 - second annular air blowing cylinder, 4 - C-shaped plate, 5 - side blowing screen plate, 6 - circulating cooling water conveying pipeline, 7 - cylinder frame, 8 - hinge. Specific embodiments

[0036] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.

[0037] The following are the test methods for relevant performance indicators in each example and comparative example:

[0038] Breaking strength, breaking strength CV value, breaking elongation, breaking elongation CV value: Refer to the standard of GB / T 14344-2022 "Test Method for Tensile Properties of Chemical Fiber Filaments", and use a fully automatic single yarn strength tester (model YG023B-II) to measure the polyester fibers prepared in each example. The specific process is as follows: First, place the polyester fibers in an environment with a temperature of 20°C and a humidity of 65% for moisture conditioning for 4 hours. Then, clamp them with upper and lower clamps (the clamping length is 250 mm), and apply a pre-tension of 0.05 cN / dtex by a manipulator to stabilize the polyester fibers. When starting the test, the lower clamp pulls the tow at a constant speed of 1000 mm / min until the tow breaks. At the same time, record the real-time data of the force sensor during the stretching process, and draw the relationship curve between strength and elongation through a data collection system. Finally, through data processing and analysis, obtain the breaking strength, breaking strength CV value, breaking elongation, and breaking elongation CV value of the tow.

[0039] Evenness variation rate: According to the "Test Method for Evenness Variation Rate of Continuous Filament Chemical Fibers - Capacitance Method" (GB / T 14346 - 2015), it is tested using a USTER5 evenness tester. The specific process is as follows: First, condition the tow in an environment with a temperature of 20°C and a humidity of 65% for 2 hours. Then, pass the tow through the two plates of the capacitor at a constant speed, convert the mass in each equal interval into an electrical signal, and the percentage of the standard deviation of all the tested electrical signals to the average value is the evenness variation rate. Among them, the test speed is 200 m / min, and the tow test time is 2.5 min.

[0040] Number of breaks: A break refers to the situation where a single filament suddenly breaks during spinning. When there is 1 break at one spinning position, it is recorded as 1 time. With a statistical cycle of 18 positions in 10 days, calculate the number of breaks at 18 positions in 24 hours based on the average value.

[0041] Thermal stress deviation: Thermal stress deviation = measured thermal stress - central value of thermal stress; The measured thermal stress is tested using a YG 367 thermal stress tester according to the standard of "Test Method for Dynamic Thermal Stress of Polyester Pre-oriented Yarn" (FZ / T 50051 - 2020). Before the test, condition the tow in an environment with a temperature of (20 ± 2)°C and a humidity of (65 ± 5)% for 4 hours. Then, pass the tow through the heating device and the drafting device at a specific speed and pre-tension (the specific parameter settings of the speed and pre-tension follow the regulations in the standard); Test the tensile stress generated by the drafting of the tow under heated conditions, which is the measured thermal stress; Central value of thermal stress: For products produced under normal process conditions, after testing according to the standard of "Test Method for Dynamic Thermal Stress of Polyester Pre-oriented Yarn" (FZ / T 50051 - 2020), the central value of thermal stress is determined through negotiation between the supplier and the demander.

[0042] A device for cooling a tow, as Figures 1 to 3 shown, includes an air box 1, an annular blowing cylinder, a C-shaped plate 4, a side blowing mesh plate 5, a circulating cooling water delivery pipeline 6, a cylinder rack 7, a hinge 8, and a magnetic attraction device;

[0043] As Figure 1 、 Figure 2 shown, the annular blowing cylinder is composed of a first annular blowing cylinder 2 in the upper section and a second annular blowing cylinder 3 in the lower section. The inner diameters of the first annular blowing cylinder 2 and the second annular blowing cylinder 3 are the same. The length of the first annular blowing cylinder 2 is 10 - 12 cm, the length of the second annular blowing cylinder 3 is 8 - 14 cm, the total length of the first annular blowing cylinder 2, the second annular blowing cylinder 3, and the side blowing mesh plate 5 is 66 - 73 cm. The mesh hole diameter of the first annular blowing cylinder 2 is 0.110 - 0.114 mm, and the mesh hole diameter of the second annular blowing cylinder 3 is 0.220 - 0.228 mm;

[0044] As Figure 1 、 Figure 3As shown, the C-shaped plate 4 is installed at the lower end of the second annular air-blowing cylinder 3. The C-shaped plate 4 is made of alloy, with a thermal conductivity of 300 - 350 W / m·K, is hollow inside and is connected to the circulating cooling water delivery pipeline 6; the lower end surface of the second annular air-blowing cylinder 3 is parallel to the horizontal plane, and the included angle between the C-shaped plate 4 and the horizontal plane is 30°;

[0045] As Figure 3 shown, the area between the tow and the second annular air-blowing cylinder 3 is an annular area, which is composed of a symmetric first semi-annular area and a second semi-annular area. The symmetry axes of the two are parallel to the side-blowing screen plate 5. The second semi-annular area is close to the side-blowing screen plate 5, and the orthographic projection of the second semi-annular area completely coincides with the C-shaped plate 4;

[0046] The second annular air-blowing cylinder 3 is installed on the air cylinder frame 7. The hinge 8 is installed at the bottom of the air box 1. The axis of the hinge 8 is horizontally arranged and parallel to the side-blowing screen plate 5. One leaf of the hinge 8 is fixedly connected to the bottom of the air box 1, and the other leaf of the hinge 8 is fixedly connected to the position of the C-shaped plate 4 closest to the side-blowing screen plate 5 and this leaf is connected to the bottom of the air box 1 through a magnetic attraction device.

[0047] Example 1

[0048] A single-plate production method for polyester fine denier porous fibers is as follows:

[0049] (1) Synthesis of polyester melt;

[0050] The overall process flow is: slurry preparation → first esterification → second esterification → pre-polycondensation → final polycondensation → polyester melt;

[0051] Relevant process parameters: the slurry temperature is 65°C, the slurry liquid level is 80%, and the mass of PTA in the slurry accounts for 69% of the total mass of PTA and EG; the temperature of the first esterification is 260°C and the pressure is 80 KPa; the temperature of the second esterification is 268°C and the pressure is 30 KPa; the upper chamber temperature of the pre-polycondensation is 276°C, the lower chamber temperature is 282°C, the upper chamber pressure is 10 KPa, and the lower chamber pressure is 1.8 KPa; the final polycondensation pressure is 180 Pa, the inlet temperature of the final polycondensation is 280°C, the middle temperature is 283°C, and the outlet temperature is 286°C;

[0052] The intrinsic viscosity of the synthesized polyester melt is 0.62 dL / g;

[0053] (2) Spinning;

[0054] The overall process flow is: spinning by the spinning pack → cooling by the first-stage annular air-blowing → cooling by the second-stage annular air-blowing → side-blowing cooling → spinning oiling → the first godet roller → pre-networking → the second godet roller → winding and forming;

[0055] Size parameters of the spinneret plate in the spinning assembly: The diameter of the spinneret plate is 120 mm, the aperture diameter of the spinneret holes is 0.14 mm, and the length of the spinneret holes is 0.52 mm;

[0056] For the first-stage ring blow cooling, the second-stage ring blow cooling, and the side blow cooling, the devices for tow cooling described above are all used. The first ring blow cylinder is used during the first-stage ring blow cooling, the second ring blow cylinder is used during the second-stage ring blow cooling, and the side blow screen plate is used during the side blow cooling; Relevant parameters of the device for tow cooling: The length of the first ring blow cylinder is 10 cm, the length of the second ring blow cylinder is 14 cm, the total length of the first ring blow cylinder, the second ring blow cylinder, and the side blow screen plate is 66 cm, the aperture diameter of the mesh holes of the first ring blow cylinder is 0.11 mm, the aperture diameter of the mesh holes of the second ring blow cylinder is 0.22 mm, and the thermal conductivity of the C-shaped plate is 300 W / m·K; The temperature of the circulating cooling water transported by the circulating cooling water pipeline is 24°C, and the flow rate is 0.08 L / min;

[0057] Relevant process parameters: The temperature of the spinning box is 287°C; The length of the windless zone is 56 mm, the cooling air temperature is 20°C, and the relative humidity of the cooling air is 75%; During the first-stage ring blow cooling, the ring blow pressure is 25 Pa; During the second-stage ring blow cooling, the ring blow pressure is 32 Pa; During the side blow cooling, the side blow wind speed is 0.6 m / s; The bundling height is 850 mm; The speed of the first godet roller is 2680 m / min; The speed of the second godet roller is 2685 m / min; The pre-network pressure is 0.08 MPa; The winding speed is 2665 m / min.

[0058] The specifications of the finally obtained polyester fine denier porous fiber are 368 dtex / 548 f, the breaking strength is 2.45 cN / dtex, the CV value of the breaking strength is 2.73%, the breaking elongation is 126.9%, the CV value of the breaking elongation is 2.41%, the evenness variation coefficient is 0.98%, the number of broken ends is 2.3 times / 18 positions·24 hours, the central value of the thermal stress is 160 cN, and the deviation of the thermal stress is 3 cN.

[0059] Comparative Example 1

[0060] A single-plate production method of polyester fine denier porous fiber, which is only different from Example 1 in that: during the first-stage ring blow cooling, the ring blow pressure is 23 Pa.

[0061] The evenness variation coefficient of the finally obtained polyester fine denier porous fiber is 1.45%, and the number of broken ends is 4.8 times / 18 positions·24 hours.

[0062] Compared with Example 1, the evenness variation coefficient and the number of broken ends of the polyester fine denier porous fiber in Comparative Example 1 increased significantly. This is because in the first-stage ring blowing cooling of Comparative Example 1, the ring blowing pressure was relatively small, and the cooling air volume was insufficient, making it impossible to cool the tow evenly and sufficiently, resulting in an increase in the evenness variation coefficient and the number of broken ends of the tow.

[0063] Comparative Example 2

[0064] A single-plate production method of polyester fine denier porous fiber, which is only different from Example 1 in that: during the second-stage ring blowing cooling, the ring blowing pressure is 30 Pa.

[0065] The evenness variation coefficient of the finally obtained polyester fine denier porous fiber is 1.90%, and the number of broken ends is 6.3 times / 18 positions·24 hours.

[0066] Compared with Example 1, the evenness variation coefficient and the number of broken ends of the polyester fine denier porous fiber in Comparative Example 2 increased significantly. This is because in the second-stage ring blowing cooling of Comparative Example 2, the ring blowing pressure was relatively small, and the cooling air volume was insufficient, making it impossible to cool the tow evenly and sufficiently, resulting in an increase in the evenness variation coefficient and the number of broken ends of the tow.

[0067] Comparative Example 3

[0068] A single-plate production method of polyester fine denier porous fiber, which is only different from Example 1 in that: the length of the first ring blowing cylinder is 8 cm.

[0069] The evenness variation coefficient of the finally obtained polyester fine denier porous fiber is 1.41%, and the number of broken ends is 8.2 times / 18 positions·24 hours.

[0070] Compared with Example 1, the evenness variation coefficient and the number of broken ends of the polyester fine denier porous fiber in Comparative Example 3 increased significantly. This is because the length of the first ring blowing cylinder in Comparative Example 3 was too short, making it impossible to match the relatively small ring blowing pressure during the stage when the fiber was in the swelling zone and the stretching zone and not yet fully solidified. The length of the air cylinder was insufficient, and the action distance of the air pressure was not enough. The fiber was extremely vulnerable to the lateral force interference of the cooling air, resulting in an increase in the lateral vibration of the fiber, and then causing doubling, hairiness, and even broken ends, and also leading to an increase in the evenness variation coefficient of the fiber.

[0071] Comparative Example 4

[0072] A single-plate production method of polyester fine denier porous fiber, which is only different from Example 1 in that: the length of the second ring blowing cylinder is 16 cm.

[0073] The evenness variation coefficient of the finally obtained polyester fine denier porous fiber is 1.49%, and the number of broken ends is 7.1 times / 18 positions·24 hours.

[0074] Compared with Example 1, the evenness variation coefficient and the number of broken ends of the polyester fine denier porous fiber in Comparative Example 4 are significantly increased. This is because the length of the second ring air blower in Comparative Example 4 is too large, which exacerbates the Bernoulli effect. The impact frequency of the fiber by the transverse pulsating air flow increases significantly, resulting in significant jitter of the fiber, thereby increasing the evenness variation coefficient and the number of broken ends.

[0075] Comparative Example 5

[0076] A single-plate production method of polyester fine denier porous fiber, which is only different from Example 1 in that: the total length of the first ring air blower, the second ring air blower and the side blowing screen plate is 64 cm.

[0077] The evenness variation coefficient of the finally obtained polyester fine denier porous fiber is 1.59%, the number of broken ends is 10.1 times / 18 positions·24 hours, and the thermal stress deviation is 15.7 cN.

[0078] Compared with Example 1, the evenness variation coefficient, the number of broken ends and the thermal stress deviation of the polyester fine denier porous fiber in Comparative Example 5 are significantly increased. This is because the total length of the first ring air blower, the second ring air blower and the side blowing screen plate in Comparative Example 5 is too small, and the cooling distance of the side blowing air is insufficient to ensure uniform cooling of the fiber, resulting in an increase in the evenness variation coefficient of the finished fiber and an increase in the thermal stress deviation; on the other hand, due to uneven cooling, the fine denier porous fiber is bundled before it is completely cured and formed, and the fiber strength is insufficient to withstand the bundling external force, resulting in an increase in broken ends.

[0079] Comparative Example 6

[0080] A single-plate production method of polyester fine denier porous fiber, which is only different from Example 1 in that: during side blowing cooling, the side blowing air speed is 0.5 m / s.

[0081] The evenness variation coefficient of the finally obtained polyester fine denier porous fiber is 2.09%, the number of broken ends is 11.4 times / 18 positions·24 hours, and the thermal stress deviation is 17.2 cN.

[0082] Compared with Example 1, the evenness variation coefficient, the number of broken ends and the thermal stress deviation of the polyester fine denier porous fiber in Comparative Example 6 are significantly increased. This is because the side blowing air speed in Comparative Example 6 is too small. On the one hand, the fiber is insufficiently cooled and undergoes elastic retraction during drawing, resulting in an increase in the diameter fluctuation range, thereby increasing the evenness variation coefficient of the finished fiber; on the other hand, since the fine denier porous fiber is bundled before it is completely cured and formed, the fiber strength is insufficient to withstand the bundling external force, resulting in an increase in broken ends; in addition, the side blowing air speed is too small and the number of holes in the filament bundle is large, so that the cooling effects near the screen plate and far from the screen plate during side blowing are inconsistent, resulting in non-uniform shrinkage inside the fiber, and further leading to non-uniform distribution of thermal stress, so the thermal stress deviation increases.

[0083] Example 2

[0084] A single - board production method for polyester fine - denier porous fibers is as follows:

[0085] (1) Synthesis of polyester melt;

[0086] The overall process flow is: slurry preparation → first esterification → second esterification → pre - polycondensation → final polycondensation → polyester melt;

[0087] Relevant process parameters: the slurry temperature is 68 °C, the slurry liquid level is 83%, the mass of PTA in the slurry accounts for 69.5% of the total mass of PTA and EG; the temperature of the first esterification is 265 °C, the pressure is 90 KPa; the temperature of the second esterification is 270 °C, the pressure is 33 KPa; the upper chamber temperature of the pre - polycondensation is 277 °C, the lower chamber temperature is 280 °C, the upper chamber pressure is 12 KPa, the lower chamber pressure is 1.9 KPa; the final polycondensation pressure is 200 Pa, the inlet temperature of the final polycondensation is 281 °C, the middle temperature is 285 °C, and the outlet temperature is 288 °C;

[0088] The intrinsic viscosity of the synthesized polyester melt is 0.63 dL / g;

[0089] (2) Spinning;

[0090] The overall process flow is: spinning by the spinning pack → cooling by the first - stage annular air blowing → cooling by the second - stage annular air blowing → cooling by side air blowing → spinning oiling → the first godet roller → pre - texturing → the second godet roller → winding and forming;

[0091] The size parameters of the spinneret plate in the spinning pack: the diameter of the spinneret plate is 120 mm, the aperture of the spinneret hole is 0.16 mm, and the length of the spinneret hole is 0.5 mm;

[0092] The first - stage annular air blowing cooling, the second - stage annular air blowing cooling, and the side air blowing cooling all use the above - mentioned device for tow cooling. The first - stage annular air blowing cooling uses the first annular air - blowing cylinder, the second - stage annular air blowing cooling uses the second annular air - blowing cylinder, and the side air blowing cooling uses the side - blowing mesh plate; the relevant parameters of the device for tow cooling: the length of the first annular air - blowing cylinder is 11 cm, the length of the second annular air - blowing cylinder is 13 cm, the total length of the first annular air - blowing cylinder, the second annular air - blowing cylinder, and the side - blowing mesh plate is 72 cm, the aperture of the mesh holes of the first annular air - blowing cylinder is 0.113 mm, the aperture of the mesh holes of the second annular air - blowing cylinder is 0.226 mm, and the thermal conductivity of the C - shaped plate is 350 W / m·K; the temperature of the circulating cooling water transported by the circulating cooling water delivery pipeline is 23 °C, and the flow rate is 0.09 L / min;

[0093] Relevant process parameters: The temperature of the spinning box is 288.5 °C; the length of the windless zone is 52 mm, the cooling air temperature is 21.5 °C, and the relative humidity of the cooling air is 79%; when the annular blowing cooling is in the first stage, the annular blowing pressure is 27 Pa; when the annular blowing cooling is in the second stage, the annular blowing pressure is 34 Pa; when the side blowing cooling is used, the side blowing wind speed is 0.7 m / s; the bundling height is 870 mm; the speed of the first godet roller is 2750 m / min; the speed of the second godet roller is 2755 m / min; the pre-network pressure is 0.09 MPa; the winding speed is 2740 m / min.

[0094] The specifications of the finally obtained polyester fine denier porous fiber are 510 dtex / 576 f, the breaking strength is 2.56 cN / dtex, the CV value of the breaking strength is 2.81%, the breaking elongation is 124.1%, the CV value of the breaking elongation is 2.7%, the unevenness of yarn evenness is 1.11%, the number of end breaks is 2 times / 18 positions·24 hours, the central value of the thermal stress is 230 cN, and the deviation of the thermal stress is 5 cN.

[0095] Comparative Example 7

[0096] A single-plate production method of polyester fine denier porous fiber, which is only different from Example 2 in that: when the side blowing cooling is used, the side blowing wind speed is 0.8 m / s.

[0097] The unevenness of yarn evenness of the finally obtained polyester fine denier porous fiber is 1.65%, the number of end breaks is 7.8 times / 18 positions·24 hours, and the deviation of the thermal stress is 25.1 cN.

[0098] Compared with Example 2, the unevenness of yarn evenness, the number of end breaks, and the deviation of the thermal stress of the polyester fine denier porous fiber in Comparative Example 7 are significantly increased. This is because the side blowing wind speed in Comparative Example 7 is too high, and the high-speed air flow instantaneously vitrifies the fiber surface layer, resulting in an increase in the deviation of the thermal stress of the fiber. At the same time, when the side blowing wind speed is too large, a core structure is likely to appear, resulting in an increase in the unevenness of yarn evenness and an increase in the number of end breaks.

[0099] Example 3

[0100] A single-plate production method of polyester fine denier porous fiber, the specific steps are as follows:

[0101] (1) Synthesis of polyester melt;

[0102] The overall process flow is: slurry preparation → first esterification → second esterification → pre-polycondensation → final polycondensation → polyester melt;

[0103] Relevant process parameters: The slurry temperature is 70°C, the slurry liquid level is 88%, and the mass of PTA in the slurry accounts for 70% of the total mass of PTA and EG; the temperature of the first esterification is 268°C and the pressure is 100 KPa; the temperature of the second esterification is 273°C and the pressure is 38 KPa; the temperature of the upper chamber of the pre-polycondensation is 278°C, the temperature of the lower chamber is 281°C, the pressure of the upper chamber is 13 KPa, and the pressure of the lower chamber is 2 KPa; the final polycondensation pressure is 250 Pa, the inlet temperature of the final polycondensation is 282°C, the middle temperature is 284°C, and the outlet temperature is 286°C;

[0104] The intrinsic viscosity of the synthesized polyester melt is 0.625 dL / g;

[0105] (2) Spinning;

[0106] The overall process flow is: spinning by the spinning pack → cooling by the first-stage ring blowing → cooling by the second-stage ring blowing → cooling by side blowing → oiling the spun yarn → the first godet roller → pre-networking → the second godet roller → winding and forming;

[0107] The dimensional parameters of the spinneret plate in the spinning pack: the diameter of the spinneret plate is 120 mm, the pore diameter of the spinneret holes is 0.15 mm, and the length of the spinneret holes is 0.51 mm;

[0108] The first-stage ring blowing cooling, the second-stage ring blowing cooling, and the side blowing cooling all use the device for tow cooling as described above. The first ring blowing cylinder is used for the first-stage ring blowing cooling, the second ring blowing cylinder is used for the second-stage ring blowing cooling, and the side blowing mesh plate is used for the side blowing cooling; the relevant parameters of the device for tow cooling: the length of the first ring blowing cylinder is 12 cm, the length of the second ring blowing cylinder is 8 cm, the total length of the first ring blowing cylinder, the second ring blowing cylinder, and the side blowing mesh plate is 73 cm, the pore diameter of the mesh of the first ring blowing cylinder is 0.114 mm, the pore diameter of the mesh of the second ring blowing cylinder is 0.228 mm, and the thermal conductivity of the C-shaped plate is 320 W / m·K; the temperature of the circulating cooling water transported by the circulating cooling water pipeline is 25°C and the flow rate is 0.1 L / min;

[0109] Relevant process parameters: the temperature of the spinning box is 287.5°C; the length of the windless area is 50 mm, the cooling air temperature is 22°C, and the relative humidity of the cooling air is 85%; during the first-stage ring blowing cooling, the ring blowing pressure is 26 Pa; during the second-stage ring blowing cooling, the ring blowing pressure is 35 Pa; during the side blowing cooling, the side blowing wind speed is 0.64 m / s; the bundling height is 920 mm; the speed of the first godet roller is 2855 m / min; the speed of the second godet roller is 2860 m / min; the pre-networking pressure is 0.08 MPa; the winding speed is 2840 m / min.

[0110] The specifications of the finally obtained fine denier porous polyester fiber are 580 dtex / 576 f, the breaking strength is 2.52 cN / dtex, the CV value of the breaking strength is 2.6%, the elongation at break is 125.6%, the CV value of the elongation at break is 2.68%, the unevenness of yarn evenness is 1.24%, the number of end breaks is 1.8 times / 18 positions·24 hours, the central value of thermal stress is 250 cN, and the deviation of thermal stress is 6 cN.

[0111] Comparative Example 8

[0112] A single-plate production method of fine denier porous polyester fiber, which is only different from Example 3 in that: the length of the first ring air blower is 14 cm.

[0113] The unevenness of yarn evenness of the finally obtained fine denier porous polyester fiber is 1.76%, and the number of end breaks is 8.4 times / 18 positions·24 hours.

[0114] Compared with Example 3, the unevenness of yarn evenness and the number of end breaks of the fine denier porous polyester fiber in Comparative Example 8 are significantly increased. This is because the excessive length of the first ring air blower in Comparative Example 8 will amplify the window effect of the air pressure parameter, resulting in an extended time for the fiber to be interfered by the transverse force of the cooling air, intensifying the fiber flutter, and increasing the unevenness of yarn evenness and the number of end breaks.

[0115] Comparative Example 9

[0116] A single-plate production method of fine denier porous polyester fiber, which is only different from Example 3 in that: the length of the second ring air blower is 6 cm.

[0117] The unevenness of yarn evenness of the finally obtained fine denier porous polyester fiber is 1.85%, the number of end breaks is 9.5 times / 18 positions·24 hours, and the deviation of thermal stress is 21.4 cN.

[0118] Compared with Example 3, the unevenness of yarn evenness, the number of end breaks and the deviation of thermal stress of the fine denier porous polyester fiber in Comparative Example 9 are significantly increased. This is because the length of the second ring air blower in Comparative Example 9 is too small, the action distance of the cooling air is short, resulting in an increase in the proportion of the residual melt in the fiber core layer, and further increasing the unevenness of yarn evenness and the deviation of thermal stress of the fiber; at the same time, due to the too small length of the second ring air blower, the fine denier porous polyester fiber will enter the side air blowing cooling prematurely, and the side air blowing cooling is relatively intense, causing the unfixed fiber to shake greatly, increasing the number of end breaks.

[0119] Comparative Example 10

[0120] A single-plate production method of fine denier porous polyester fiber, which is only different from Example 3 in that: the total length of the first ring air blower, the second ring air blower and the side air blowing net plate is 75 cm.

[0121] The evenness variation coefficient of the finally obtained fine denier porous polyester fiber is 2.1%, the number of broken ends is 12.8 times / 18 positions·24 hours, and the thermal stress deviation is 27.0 cN.

[0122] Compared with Example 3, the evenness variation coefficient, the number of broken ends, and the thermal stress deviation of the fine denier porous polyester fiber in Comparative Example 10 are significantly increased. This is because the total length of the first ring air blowing cylinder, the second ring air blowing cylinder, and the side blowing mesh plate in Comparative Example 10 is too large, which will amplify the window effect of the wind speed parameter, and the cooling length is too long, and the bunching position of the fiber bundle is relatively close, resulting in an increase in the spinning tension, and thus an increase in the evenness variation coefficient, the number of broken ends, and the thermal stress deviation.

[0123] Comparative Example 11

[0124] A single-plate production method of a fine denier porous polyester fiber, which is only different from Example 3 in that: during the second-stage ring air blowing cooling, the ring air blowing pressure is 38 Pa.

[0125] The evenness variation coefficient of the finally obtained fine denier porous polyester fiber is 1.68%, and the number of broken ends is 6.7 times / 18 positions·24 hours.

[0126] Compared with Example 3, the evenness variation coefficient and the number of broken ends of the fine denier porous polyester fiber in Comparative Example 11 are significantly increased. This is because the ring air blowing pressure during the second-stage ring air blowing cooling in Comparative Example 11 is too high, which will cause adjacent single filaments to generate synchronous vibration, resulting in an increase in the probability of filament merging, and thus an increase in the evenness variation coefficient and the number of broken ends.

[0127] Example 4

[0128] A single-plate production method of a fine denier porous polyester fiber is as follows:

[0129] (1) Synthesis of polyester melt;

[0130] The overall process flow is: slurry preparation → first esterification → second esterification → pre-polycondensation → final polycondensation → polyester melt;

[0131] Relevant process parameters: the slurry temperature is 75 °C, the slurry liquid level is 90%, and the mass of PTA in the slurry accounts for 71% of the total mass of PTA and EG; the temperature of the first esterification is 270 °C, and the pressure is 110 KPa; the temperature of the second esterification is 275 °C, and the pressure is 40 KPa; the upper chamber temperature of the pre-polycondensation is 280 °C, the lower chamber temperature is 278 °C, the upper chamber pressure is 15 KPa, and the lower chamber pressure is 2.2 KPa; the final polycondensation pressure is 300 Pa, the inlet temperature of the final polycondensation is 281 °C, the middle temperature is 285 °C, and the outlet temperature is 287 °C;

[0132] The intrinsic viscosity of the synthesized polyester melt is 0.628 dL / g;

[0133] (2) Spinning;

[0134] The overall process flow is: spinning by the spinning pack → cooling by the first-stage ring air-blowing → cooling by the second-stage ring air-blowing → cooling by the side air-blowing → oiling the spun yarn → the first godet roller → pre-networking → the second godet roller → winding and forming;

[0135] The dimensional parameters of the spinneret plate in the spinning pack: the diameter of the spinneret plate is 120 mm, the aperture diameter of the spinneret holes is 0.14 mm, and the length of the spinneret holes is 0.51 mm;

[0136] For the first-stage ring air-blowing cooling, the second-stage ring air-blowing cooling, and the side air-blowing cooling, the devices for tow cooling as described above are all used. The first ring air-blowing cylinder is used during the first-stage ring air-blowing cooling, the second ring air-blowing cylinder is used during the second-stage ring air-blowing cooling, and the side air-blowing screen plate is used during the side air-blowing cooling; The relevant parameters of the device for tow cooling: the length of the first ring air-blowing cylinder is 11 cm, the length of the second ring air-blowing cylinder is 10 cm, the total length of the first ring air-blowing cylinder, the second ring air-blowing cylinder, and the side air-blowing screen plate is 69 cm, the aperture diameter of the mesh holes of the first ring air-blowing cylinder is 0.112 mm, the aperture diameter of the mesh holes of the second ring air-blowing cylinder is 0.224 mm, and the thermal conductivity of the C-shaped plate is 330 W / m·K; The temperature of the circulating cooling water transported by the circulating cooling water pipeline is 23 °C, and the flow rate is 0.09 L / min;

[0137] Relevant process parameters: the temperature of the spinning box is 289 °C; the length of the windless area is 60 mm, the cooling air temperature is 20.5 °C, and the relative humidity of the cooling air is 82%; during the first-stage ring air-blowing cooling, the ring air-blowing pressure is 28 Pa; during the second-stage ring air-blowing cooling, the ring air-blowing pressure is 33 Pa; during the side air-blowing cooling, the side air-blowing speed is 0.69 m / s; the bundling height is 950 mm; the speed of the first godet roller is 2685 m / min; the speed of the second godet roller is 2690 m / min; the pre-networking pressure is 0.09 MPa; the winding speed is 2680 m / min.

[0138] The specifications of the finally obtained polyester fine denier porous fiber are 368 dtex / 576 f, the breaking strength is 2.58 cN / dtex, the CV value of the breaking strength is 3.09%, the breaking elongation is 124.9%, the CV value of the breaking elongation is 2.81%, the evenness variation coefficient is 1.15%, the number of breaks is 2.5 times / 18 positions·24 hours, the central value of the thermal stress is 160 cN, and the deviation of the thermal stress is 4 cN.

[0139] Comparative Example 12

[0140] A single-plate production method of polyester fine denier porous fiber, which is only different from Example 4 in that: during the first-stage ring air-blowing cooling, the ring air-blowing pressure is 30 Pa.

[0141] The evenness variation coefficient of the finally obtained fine denier porous polyester fiber is 1.8%, the number of broken ends is 8.4 times / 18 positions·24 hours, and the thermal stress deviation is 16.4 cN.

[0142] Compared with Example 4, the evenness variation coefficient, the number of broken ends, and the thermal stress deviation of the fine denier porous polyester fiber in Comparative Example 12 are significantly increased. This is because the air pressure of the annular air blowing during the first-stage annular air blowing cooling in Comparative Example 12 is too high. Due to the large number of fiber holes, the unfully solidified fibers are impacted by the strong air flow, resulting in the transverse vibration of the fibers, triggering filament doubling, hairiness, and even broken ends, which increases the evenness variation coefficient and the number of broken ends. At the same time, the too high air pressure of the annular air blowing leads to uneven cooling of the inner and outer layers of the fibers, making the uniformity of the forming process worse, so the thermal stress deviation increases.

[0143] Comparative Example 13

[0144] A single-plate production method of fine denier porous polyester fiber is different from Example 4 only in that: the device for cooling the tow has no C-shaped plate.

[0145] The evenness variation coefficient of the finally obtained fine denier porous polyester fiber is 2.37%, the number of broken ends is 10.6 times / 18 positions·24 hours, and the thermal stress deviation is 19.2 cN.

[0146] Compared with Example 4, the evenness variation coefficient, the number of broken ends, and the thermal stress deviation of the fine denier porous polyester fiber in Comparative Example 13 are significantly increased. This is because in Comparative Example 13, at the junction of the annular air blowing cooling zone and the side air blowing cooling zone, the hot air that affects the side air blowing cooling effect flowing downward from the annular air blowing cooling zone is not cooled down and blocked from moving downward. Due to the large number of holes in the fine denier porous polyester fiber and the relatively high temperature in the second annular air blowing cylinder, when the tow leaves the second annular air blowing cylinder, a large amount of hot air with a relatively high temperature will blow vertically downward. At the moment when the tow contacts the side air blowing, the side air blowing will be blocked and heated up by the hot air, which will cause the cooling effect of the filament to be worse the farther away from the air outlet end of the side air blowing, making the uniformity of the forming process worse, so the thermal stress deviation increases; in addition, due to the large difference between the cold and hot air flows, it is easy to cause the disorder of single filaments, resulting in an increase in the evenness variation coefficient and the number of broken ends.

Claims

1. A single-plate production method for polyester fine-denier porous fibers, including a spinning process of a spinning assembly and a cooling process, characterized in that, During cooling, first-stage annular blow air cooling, second-stage annular blow air cooling and side blow air cooling are carried out in sequence; During the first-stage annular blow air cooling, the annular blow air pressure is 25 - 28 Pa, and the length of the first annular blow air cylinder used is 10 - 12 cm; During the second-stage annular blow air cooling, the annular blow air pressure is 32 - 35 Pa, and the length of the second annular blow air cylinder used is 8 - 14 cm; The total length of the first annular blow air cylinder, the second annular blow air cylinder and the side blow screen plate is 66 - 73 cm, and the side blow air speed is 0.60 - 0.70 m / s; At the junction of the annular blow air cooling zone and the side blow air cooling zone, the hot air flowing out from the annular blow air cooling zone downward and affecting the side blow air cooling effect is cooled down and its downward movement is blocked; The specification of the polyester fine denier porous fiber is 368 - 580 dtex / 548 - 576 f.

2. The single-plate production method of a polyester fine denier porous fiber according to claim 1, characterized in that, The first annular blow air cylinder and the second annular blow air cylinder are the upper and lower sections of the same annular blow air cylinder. The inner diameters of the first annular blow air cylinder and the second annular blow air cylinder are the same. The pore diameter of the mesh holes of the first annular blow air cylinder is 0.110 - 0.114 mm, and the pore diameter of the mesh holes of the second annular blow air cylinder is 0.220 - 0.228 mm.

3. A single-board production method of a polyester fine-denier porous fiber according to claim 1, characterized in that At the junction of the annular blow air cooling zone and the side blow air cooling zone, the realization method of cooling down the hot air flowing out from the annular blow air cooling zone downward and affecting the side blow air cooling effect and blocking its downward movement is: Install 1 C-shaped plate at the lower end of the second annular blow air cylinder. The material of the C-shaped plate is alloy, the thermal conductivity is 300 - 350 W / m·K, it is hollow inside and is connected to the circulating cooling water delivery pipeline; The area between the tow and the second annular blow air cylinder is an annular area, which is composed of a symmetric first semi-annular area and a second semi-annular area. Their symmetry axes are parallel to the side blow screen plate. The second semi-annular area is close to the side blow screen plate, and the orthographic projection of the second semi-annular area completely coincides with that of the C-shaped plate.

4. A single-plate production method of a polyester fine-denier porous fiber according to claim 3, characterized in that, The lower end face of the second annular blow air cylinder is parallel to the horizontal plane, and the included angle between the C-shaped plate and the horizontal plane is 30°.

5. The single-board production method of a polyester fine denier porous fiber according to claim 4, characterized in that, The second annular blow air cylinder is installed on the air cylinder frame. Hinges are installed at the bottom of the air box. The axis of the hinges is horizontally arranged and parallel to the side blow screen plate. One leaf of the hinges is fixedly connected to the bottom of the air box, and the other leaf of the hinges is fixedly connected to the position of the C-shaped plate closest to the side blow screen plate and this leaf is connected to the bottom of the air box through a magnetic attraction device.

6. A method for producing a single board of polyester fine denier porous fiber according to claim 3, characterized in that, The temperature of the circulating cooling water conveyed by the circulating cooling water delivery pipeline is 23 - 25 °C, and the flow rate is 0.08 - 0.1 L / min.

7. A single-plate production method of a polyester fine denier porous fiber according to claim 1, characterized in that The overall process flow is: spinning by the spinning pack → cooling → spinning oiling → the first godet roller → pre-network → the second godet roller → winding and forming.

8. A single-board production method of a polyester fine-denier porous fiber according to claim 7, characterized in that, The diameter of the spinneret is 120 mm, the aperture diameter of the spinneret holes is 0.14 - 0.16 mm, the length of the spinneret holes is 0.50 - 0.52 mm, the temperature of the spinning box is 287 - 289 °C, the length of the windless zone is 50 - 60 mm, the temperature of the cooling air is 20 - 22 °C, the relative humidity of the cooling air is 75 - 85%, the bundling height is 850 - 950 mm, the speed of the first godet roller is 2680 - 2855 m / min, the speed of the second godet roller is 2685 - 2860 m / min, the pre-network pressure is 0.08 - 0.09 MPa, and the winding speed is 2665 - 2840 m / min.

9. A method for producing a single board of polyester fine denier porous fibers according to claim 7, characterized in that, The breaking strength of the polyester fine denier porous fiber is ≥ 2.45 cN / dtex, the CV value of the breaking strength is ≤ 3.09%, the breaking elongation is 124.1 - 126.9%, the CV value of the breaking elongation is ≤ 2.81%, the evenness variation coefficient is ≤ 1.24%, the number of end breaks is ≤ 2.5 times / 18 positions·24 hours, and the thermal stress deviation is ≤ M × 3%; M is the central value of the thermal stress, in the unit of cN.

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