Preparation method of low-pore-number high-holding high-strength nylon 6

Abstract

This invention relates to a method for preparing low-pore-count, high-cohesion, and high-strength nylon 6: Nylon 6 chips with a moisture content of 350-450 ppm are extruded through a screw extruder and quantitatively conveyed to a spinning assembly by a metering pump to form fibers. The radial cross-section of the fibers has several hooks spaced along the circumferential direction. The extruded fibers are sequentially fed into a slow cooler and a monomer suction device, and then uniformly cooled by side blowing to form filament bundles. The filament bundles are fed into a spinning bundle strengthening oiling device with an oil nozzle, guide hooks, and a blower bundle, allowing several filament bundles to be oiled by the oil nozzles and their corresponding guide hooks. Finally, the several filament bundles enter the blower bundle together and are hooked together by compressed air. The oiled and bundled filament bundles are sent to a pre-networker to blow the oil agent evenly onto the filament bundles, and then stretched and heated by a first and second roller, and disturbed by a main networker. After the spinning tension is adjusted by a guide disc, the filament bundles are wound into a filament cake at the winding head. The high-strength nylon 6 filament bundles prepared by this method have strong cohesion and are not easily separated under external force. When woven into fabric, they can play a very good anti-snagging role.

Description

Technical Field

[0001] This invention relates to a method for preparing a low-pore-count, high-cohesion, high-strength nylon 6. Background Technology

[0002] High-strength nylon 6 is widely used in aerospace, military equipment, and sportswear due to its high breaking strength. However, precisely because of its high strength, when preparing fibers with low porosity (F number below 10), several challenges arise: 1. The small number of monofilaments makes it difficult to create a network using air pressure; 2. To achieve higher strength (>6.0 cN / detx), the fiber draw ratio is high during spinning, resulting in greater fiber stretching and stiffness, making it difficult to create the required number of network points using air pressure. Furthermore, the higher the strength of nylon 6, the more difficult it becomes to create a network. Additionally, most nylon 6 fibers now have a circular cross-section, which results in poor fiber cohesion without network points, leading to easy fraying of the fiber bundles. This is detrimental to subsequent weaving and results in fabrics with poor anti-snagging properties. Summary of the Invention

[0003] The purpose of this invention is to provide a method for preparing high-strength nylon 6 with low porosity and high cohesion. The high-strength nylon 6 filaments prepared by this method have strong cohesion and are not easily separated under external force. Moreover, the fabric woven from them has very good anti-snagging properties.

[0004] The technical solution of this invention is: a method for preparing low-pore-count, high-cohesion, high-strength nylon 6, comprising the following steps:

[0005] (1) Nylon 6 chips with a moisture content of 350-450ppm are extruded through a screw extruder and quantitatively transported to the spinning assembly by a metering pump to form fibers. The radial cross section of the fibers is provided with several hooks at intervals along the circumferential direction.

[0006] (2) The ejected fibers pass through a slow cooler and a single-unit suction device in sequence, and are then cooled evenly by side blowing air;

[0007] (3) Then the filament bundle is fed into a spinning bundle strengthening oiling device with an oil nozzle, a guide hook and a blower bundle, which divides all the monofilaments ejected from a spinneret into several filament bundles, which are oiled by the oil nozzle and the corresponding guide hooks respectively. Finally, the several filament bundles enter the blower bundle together and are hooked together by compressed air.

[0008] (4) The oiled bundles are sent to the pre-networker to blow the oil evenly on the bundles, and then they are stretched and shaped by the first and second rollers, and the main networker disturbs the upper network to improve the cohesion of the bundles.

[0009] (5) After the spinning tension is adjusted by the guide plate, the yarn is wound into a cake at the winding head.

[0010] Furthermore, in step (1), the set temperature of the screw extruder is 255-280℃.

[0011] Furthermore, the spinning assembly is provided with a spinneret, and the spinneret is provided with a plurality of spinnerets of the same shape and size at intervals. The spinnerets are composed of at least three arrow-shaped structures arranged at intervals along the circumference.

[0012] Further, in step (2), the temperature of the slow cooler is 230-270℃; the pressure at the smoke extraction point of the single suction device is 0.1-0.3 barr; the wind speed of the side blowing is 0.3-0.6 m / s, and the wind temperature is 19-23℃.

[0013] Furthermore, the spinning bundle reinforcement oiling device includes an oil nozzle frame, on which at least three oil nozzles for spinning oiling are installed at intervals. A guide hook frame is provided on the lower side of the oil nozzle frame, on which guide hooks corresponding to the number of oil nozzles and used for guiding the yarn are installed at intervals. A blower bundler frame is provided on the lower side of the guide hook frame, on which blower bundlers are installed for the yarn to pass through and achieve yarn bundle bundling.

[0014] Furthermore, the nozzle holder includes a main oil supply pipe connected to the oil supply pipe, a fixing ring is provided at the other end of the main oil supply pipe, and oil supply branch pipes are installed at intervals on the fixing ring. The nozzle is installed at the other end of the oil supply branch pipe. The nozzle is vertically provided with a through groove for the filament bundle to pass through, and is provided with an oil spray port connected to the oil supply branch pipe.

[0015] Furthermore, the air-blowing cluster includes an air guide pipe, one end of which is connected to a compressed air pipe, and a switch for controlling the compressed air pressure is provided on the compressed air pipe. The other end of the air guide pipe is provided with a clustering hole, and an arc-shaped air-blowing channel is provided on the air guide pipe that leads into the clustering hole. The outlet direction of the arc-shaped air-blowing channel is tangent to the side wall of the clustering hole. An arc-shaped installation channel for installing the spinning element is also provided on the outside of the clustering hole and communicates with the clustering hole.

[0016] Further, in step (4), the pressure of the pre-networker is 0.05-0.1MPa; the speeds of the first and second rollers are 1200-2000m / min and 3600-5000m / min, respectively, and the temperature of the second roller is 140-205℃; the pressure of the main networker is 0.45-0.75MPa.

[0017] Furthermore, in step (4), a first main network device and a second main network device are provided, and the pressure of the first main network device and the second main network device is 0.45-0.75MPa.

[0018] Furthermore, in step (5), the speed of the guide disc is 3500-4960 m / min, and the winding speed of the winding head is 3400-4900 m / min.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] 1. This invention changes the shape of the fiber cross-section to create "hooks" in the fiber bundle cross-section. During spinning, after the fiber bundle is agitated by the air pressure of the networker, the fibers can hook together and are not easily separated under external force, thus improving the cohesion of the fiber bundle.

[0021] 2. The low-pore-count high-strength nylon 6 prepared by this invention exhibits excellent cohesion between its individual filaments, making it difficult for individual filaments to detach, which is beneficial for subsequent weaving and processing, and also improves the anti-snagging performance of the fabric. The obtained low-pore-count high-strength nylon 6 has a strength of 5.5-9.0 cN / dtex, a breaking elongation of 22-35%, and a network point count of 5-15 per meter, while the low-pore-count high-strength nylon 6 prepared using conventional methods has only 1-7 network points per meter.

[0022] 3. Conventional spinning processes mainly use one main networker to apply a network to the yarn bundle. This invention adds a network nozzle to the existing process, using two main networkers to apply a network to the yarn bundle, thereby increasing the number of network points in the yarn bundle and improving the cohesion of the yarn bundle. Attached Figure Description

[0023] Figure 1 This is a schematic diagram showing the cooperation between the spinneret and the spinning bundle reinforcement oiling device of the present invention;

[0024] Figure 2 This is a schematic diagram of the spinneret hole structure of the present invention;

[0025] Figure 3 For the present invention Figure 1 A schematic diagram of direction A;

[0026] Figure 4 This is an enlarged schematic diagram of the nozzle of the present invention;

[0027] Figure 5 For the present invention Figure 1 A schematic diagram of direction B;

[0028] Figure 6 For the present invention Figure 1 A schematic diagram of direction C;

[0029] Figure 7 This is a schematic diagram of the cross-section after spinning and bundling according to the present invention;

[0030] In the diagram: 1-Fiber 1a-Hook 10-Spinneret 11-Spinneret Hole 12-Outlet Channel 20-Oil Nozzle Holder 21-Oil Main Pipe 22-Fixing Ring 23-Oil Branch Pipe 30-Oil Nozzle 31-Through Groove 32-Oil Inlet 40-Guide Hook Holder 41-Fixing Rod 42-Connecting Ring 43-Connecting Rod 50-Guide Hook 51-Through Hole 52-Spinning Inlet 60-Blower Bundle 62-Bundling Hole 63-Arc-shaped Blower Channel 64-Arc-shaped Installation Channel. Detailed Implementation

[0031] To make the above features and advantages of the present invention more readily understood, specific embodiments are described below in conjunction with the accompanying drawings, but the present invention is not limited thereto.

[0032] Example 1 (Reference) Figures 1 to 7

[0033] A method for preparing low-pore-number, high-cohesion, high-strength nylon 6, comprising the following steps:

[0034] (1) Nylon 6 chips with a moisture content of 350 ppm are fed into a screw extruder through a hopper for extrusion. The melt temperature in the screw extruder is set to 260°C. The melt extruded from the screw extruder is transported to a spinning metering pump through a melt pipeline, and then quantitatively delivered to the spinning assembly by the metering pump. Due to the action of the metal grit and nonwoven fabric in the spinning assembly, the polymer melt forms high pressure at the spinning assembly, which allows it to be ejected from the spinneret to form fibers. The radial cross section of the fibers is provided with a number of hooks 1a spaced along the circumferential direction.

[0035] (2) The ejected fiber 1 passes through the slow cooler in sequence. The temperature of the slow cooler is 265℃. Its main function is to allow the fiber to cool slowly after it is ejected from the spinneret. This provides more time for the macromolecular chains in the fiber to move in orientation, thereby improving the strength of the fiber.

[0036] (3) Then, the smoke is drawn through a single-unit suction device. The pressure at the smoke suction point is 0.12 barr. The smoke suction is to remove the single-unit generated at the spinneret to prevent it from adhering to the spinneret surface or the fiber and affecting the stability of the spinning production. Then, the fiber bundle is formed by uniform cooling by side blowing. The side blowing wind speed is 0.35 m / s and the wind temperature is 19.5℃. Its function is to uniformly cool the fiber bundle so that it has a certain strength to be drawn.

[0037] (4) Then the filament bundle is fed into the spinning bundle enhancement oiling device with oil nozzle 30, guide hook 50 and air blower bundle 60. All the monofilaments sprayed from a spinneret are divided into several strands and oiled by the oil nozzles respectively. Then each strand passes through the guide hook under the corresponding oil nozzle. Finally, the strands enter the air blower bundle together and are hooked together by compressed air.

[0038] (5) The oiled bundles are sent to the pre-networker through the spinning tunnel. The pressure of the pre-networker is 0.07 MPa. Its main function is to blow the oil on the bundles evenly, which is beneficial to the product performance and production stability. In addition, it also has the function of applying a network to the bundles.

[0039] (6) Then the filament bundle is stretched and shaped by the first and second rollers. The speeds of the first and second rollers are 1350 m / min and 3750 m / min, respectively, and the temperature of the second roller is 165°C. The first and second rollers mainly play a stretching role on the filament bundle, so that the filament bundle has a certain strength. The temperature of the second roller can provide the energy required for the molecular chains in the filament bundle to move in the direction of the force under the action of the stretching force. The so-called thermal stretching prevents the filament bundle from breaking or producing fuzz under high speed and high stretching ratio.

[0040] (7) The filament bundle is disturbed and networked by the main networker. The pressure of the main networker is 0.45 MPa. Compressed air is used to disturb the filament bundle, thereby forming a network to improve the cohesion of the filament bundle. Because low-pore-count (F number less than 10) high-strength nylon 6 has high strength, and the higher the strength, the harder the fiber, these two factors make it difficult for low-pore-count high-strength nylon 6 to form network points. Therefore, this invention uses a main networker to form a network on the filament bundle, combined with a special irregular cross-section with "hooks" on the filament bundle cross-section, so that the number of network points of low-pore-count high-strength nylon 6 is significantly higher than that of high-strength nylon 6 with a circular uniform cross-section.

[0041] (8) After the spinning tension is adjusted by the guide disc, the yarn is wound into a cake at the winding head. The speed of the guide disc is 3725 m / min, and the winding speed of the winding head is 3700 m / min.

[0042] In this embodiment, to ensure that the spun fibers can hook together after being agitated by the air pressure of the spinning device, making them less prone to separation under external force and improving the cohesion of the fiber bundle, the spinning assembly is equipped with a spinneret 10. The spinneret is provided with a plurality of spinneret holes 11 of the same shape and size, spaced apart. The spinneret holes are shaped like arrows, arranged at least three times outwards along the circumferential direction, with the other ends of the arrows connected and identical. This results in hooked sections on the extruded spun fibers, improving the cohesion of the fiber bundle.

[0043] In this embodiment, the spinning bundle reinforcement oiling device includes an oil nozzle frame 20, on which at least three oil nozzles 30 for spinning oiling are installed at intervals. A guide hook frame 40 is located below the oil nozzle frame, on which guide hooks 50, corresponding to the number of oil nozzles and used for guiding the yarn, are installed at intervals. A blower bundler frame is located below the guide hook frame, on which blower bundlers 60 are installed for the yarn to pass through and bundle together. This ensures that multiple yarn bundles are hooked together after passing through the spinning bundle reinforcement oiling device.

[0044] In this embodiment, for better installation of the nozzle, the nozzle holder includes a main oil supply pipe 21 connected to the oil supply pipe. A retaining ring 22 is provided at the other end of the main oil supply pipe, and branch oil supply pipes 23 are installed at intervals on the retaining ring. The nozzle is installed at the other end of the branch oil supply pipes. The nozzle has a vertically arranged through groove 31 for the filament to pass through, and an oil spray nozzle 32 communicating with the branch oil supply pipes. The nozzle is made of ceramic.

[0045] In this embodiment, to facilitate the installation of the guide hook, the guide hook frame includes a fixing rod 41, with a connecting ring 42 fixed to the other end of the fixing rod. Guide hooks 50 are installed at intervals along the circumferential direction via the connecting rod 43 on the connecting ring. For convenient spinning guidance and installation, the guide hook is spiral-shaped, with a through hole 51 in the middle for the spinning yarn to pass through, and a spinning inlet 52 leading into the through hole. The guide hook is made of ceramic.

[0046] In this embodiment, to achieve the bundling of several strands of spun yarn into one by air pressure, the air-blowing bundler includes an air guide pipe 61. One end of the air guide pipe is connected to a compressed air pipe, and a switch for controlling the compressed air pressure is provided on the compressed air pipe. The other end of the air guide pipe is provided with a bundling hole 62 for the spun yarn to pass through. An arc-shaped air blowing channel 63 is provided on the air guide pipe leading into the bundling hole. The width of the arc-shaped air blowing channel gradually narrows from the air guide pipe towards the bundling hole, thereby allowing the incoming air to be compressed again. Furthermore, the outlet direction of the arc-shaped air blowing channel is tangent to the side wall of the bundling hole, so that the compressed air blows around the bundling hole in one direction, causing the spun yarn to rotate and wind in the direction of rotation of the compressed air within the bundling hole. An arc-shaped mounting channel 64, communicating with the bundling hole, is also provided on the outside of the bundling hole for mounting the spun yarn, so that the spun yarn can be installed into the bundling hole.

[0047] In this embodiment, the air-blowing cluster is made of ceramic, and the diameter of the clustering hole is 0.5~1.5cm, and the height of the clustering hole is 1-2cm. During operation, the air pressure of the air-blowing cluster is 0.03~0.15MPa.

[0048] Since the compressed air is blown in one direction around the bundling hole, the filament bundles will rotate and intertwine with each other at the bundling hole. Because the cross-section of the filament bundle has a hook structure, the filament bundles between each other will hook together during this process, thereby enhancing the cohesion between the filament bundles.

[0049] In this embodiment, the slow cooler, the single-unit suction device, and the side blower are arranged between the spinneret and the nozzle holder.

[0050] In this embodiment, in step (7), two main networkers are provided, namely a first main networker and a second main networker, both with a pressure of 0.51 MPa. The second main networker may or may not be used, depending on the specific situation. When using two main networkers to network the filament bundle, the special irregular cross-section with "hooks" on the filament bundle cross-section can further increase the number of network points of the filament bundle, thereby improving the cohesion of the filament bundle.

[0051] In this embodiment, the produced fiber specification is FDY30D05F, and the fiber breaking strength is 6.8 cN / dtex. The number of fiber bundle network points is 8 per meter.

[0052] A cross-sectional photo of the produced 30D05F high-strength nylon 6 shows that the filament bundles are connected to each other by hooks in the middle area of ​​the image.

[0053] Example 2 (Reference) Figures 1 to 7

[0054] A method for preparing low-pore-number, high-cohesion, high-strength nylon 6, comprising the following steps:

[0055] (1) Nylon 6 chips with a moisture content of 400 ppm are fed into a screw extruder through a hopper for extrusion. The melt temperature in the screw extruder is set to 268°C. The melt extruded from the screw extruder is transported to a spinning metering pump through a melt pipeline, and then quantitatively delivered to the spinning assembly by the metering pump. Due to the action of the metal grit and nonwoven fabric in the spinning assembly, the polymer melt forms high pressure at the spinning assembly, which allows it to be ejected from the spinneret to form fibers. The radial cross-section of the fibers is provided with a number of hooks 1a spaced along the circumferential direction.

[0056] (2) The ejected fiber 1 passes through the slow cooler in sequence. The temperature of the slow cooler is 250℃. Its main function is to allow the fiber to cool slowly after it is ejected from the spinneret. This provides more time for the macromolecular chains in the fiber to move in orientation, thereby improving the strength of the fiber.

[0057] (3) Then, the smoke is drawn through a single-unit suction device. The pressure at the smoke suction point is 0.2 barr. The smoke suction is to remove the single-unit generated at the spinneret to prevent it from adhering to the spinneret surface or the fiber and affecting the stability of the spinning production. Then, the fiber bundle is formed by uniform cooling by side blowing. The side blowing speed is 0.45 m / s and the wind temperature is 21℃. Its function is to uniformly cool the fiber bundle so that it has a certain strength to be drawn.

[0058] (4) Then the filament bundle is fed into the spinning bundle enhancement oiling device with oil nozzle 30, guide hook 50 and air blower bundle 60. All the monofilaments sprayed from a spinneret are divided into several strands and oiled by the oil nozzles respectively. Then each strand passes through the guide hook under the corresponding oil nozzle. Finally, the strands enter the air blower bundle together and are hooked together by compressed air.

[0059] (5) The oiled bundles are sent to the pre-networker through the spinning tunnel. The pressure of the pre-networker is 0.055 MPa. Its main function is to blow the oil on the bundles evenly, which is beneficial to the product performance and production stability. In addition, it also has the function of networking the bundles.

[0060] (6) Then the filament bundle is stretched and shaped by the first and second rollers. The speeds of the first and second rollers are 1650 m / min and 4950 m / min, respectively, and the temperature of the second roller is 175°C. The first and second rollers mainly play a stretching role on the filament bundle, so that the filament bundle has a certain strength. The temperature of the second roller can provide the energy required for the molecular chains in the filament bundle to move in the direction of the force under the action of the stretching force. The so-called thermal stretching prevents the filament bundle from breaking or producing fuzz under high speed and high stretching ratio.

[0061] (7) The filament bundle is disturbed and networked by the main networker. The pressure of the main networker is 0.55 MPa. Compressed air is used to disturb the filament bundle, thereby forming a network to improve the cohesion of the filament bundle. Because low-pore-count (F number less than 10) high-strength nylon 6 has high strength, and the higher the strength, the harder the fiber, these two factors make it difficult for low-pore-count high-strength nylon 6 to form network points. Therefore, this invention uses a main networker to form a network on the filament bundle, combined with a special irregular cross-section with "hooks" on the filament bundle cross-section, so that the number of network points of low-pore-count high-strength nylon 6 is significantly higher than that of high-strength nylon 6 with a circular uniform cross-section.

[0062] (8) After the spinning tension is adjusted by the guide disc, the yarn is wound into a cake at the winding head. The speed of the guide disc is 4900 m / min, and the winding speed of the winding head is 4870 m / min.

[0063] In this embodiment, to ensure that the spun fibers can hook together after being agitated by the air pressure of the spinning device, making them less prone to separation under external force and improving the cohesion of the fiber bundle, the spinning assembly is equipped with a spinneret 10. The spinneret is provided with a plurality of spinneret holes 11 of the same shape and size, spaced apart. The spinneret holes are shaped like arrows, arranged at least three times outwards along the circumferential direction, with the other ends of the arrows connected and identical. This results in hooked sections on the extruded spun fibers, improving the cohesion of the fiber bundle.

[0064] In this embodiment, the spinning bundle reinforcement oiling device includes an oil nozzle frame 20, on which at least three oil nozzles 30 for spinning oiling are installed at intervals. A guide hook frame 40 is located below the oil nozzle frame, on which guide hooks 50, corresponding to the number of oil nozzles and used for guiding the yarn, are installed at intervals. A blower bundler frame is located below the guide hook frame, on which blower bundlers 60 are installed for the yarn to pass through and bundle together. This ensures that multiple yarn bundles are hooked together after passing through the spinning bundle reinforcement oiling device.

[0065] In this embodiment, for better installation of the nozzle, the nozzle holder includes a main oil supply pipe 21 connected to the oil supply pipe. A retaining ring 22 is provided at the other end of the main oil supply pipe, and branch oil supply pipes 23 are installed at intervals on the retaining ring. The nozzle is installed at the other end of the branch oil supply pipes. The nozzle has a vertically arranged through groove 31 for the filament to pass through, and an oil spray nozzle 32 communicating with the branch oil supply pipes. The nozzle is made of ceramic.

[0066] In this embodiment, to facilitate the installation of the guide hook, the guide hook frame includes a fixing rod 41, with a connecting ring 42 fixed to the other end of the fixing rod. Guide hooks 50 are installed at intervals along the circumferential direction via the connecting rod 43 on the connecting ring. For convenient spinning guidance and installation, the guide hook is spiral-shaped, with a through hole 51 in the middle for the spinning yarn to pass through, and a spinning inlet 52 leading into the through hole. The guide hook is made of ceramic.

[0067] In this embodiment, to achieve the bundling of several strands of spun yarn into one by air pressure, the air-blowing bundler includes an air guide pipe 61. One end of the air guide pipe is connected to a compressed air pipe, and a switch for controlling the compressed air pressure is provided on the compressed air pipe. The other end of the air guide pipe is provided with a bundling hole 62 for the spun yarn to pass through. An arc-shaped air blowing channel 63 is provided on the air guide pipe leading into the bundling hole. The width of the arc-shaped air blowing channel gradually narrows from the air guide pipe towards the bundling hole, thereby allowing the incoming air to be compressed again. Furthermore, the outlet direction of the arc-shaped air blowing channel is tangent to the side wall of the bundling hole, so that the compressed air blows around the bundling hole in one direction, causing the spun yarn to rotate and wind in the direction of rotation of the compressed air within the bundling hole. An arc-shaped mounting channel 64, communicating with the bundling hole, is also provided on the outside of the bundling hole for mounting the spun yarn, so that the spun yarn can be installed into the bundling hole.

[0068] In this embodiment, the air-blowing cluster is made of ceramic, and the diameter of the clustering hole is 0.5~1.5cm, and the height of the clustering hole is 1-2cm. During operation, the air pressure of the air-blowing cluster is 0.03~0.15MPa.

[0069] Since the compressed air is blown in one direction around the bundling hole, the filament bundles will rotate and intertwine with each other at the bundling hole. Because the cross-section of the filament bundle has a hook structure, the filament bundles between each other will hook together during this process, thereby enhancing the cohesion between the filament bundles.

[0070] In this embodiment, the slow cooler, the single-unit suction device, and the side blower are arranged between the spinneret and the nozzle holder.

[0071] In this embodiment, in step (7), two main networkers are set up, namely a first main networker and a second main networker, and the pressure of both the first and second main networkers is 0.62 MPa. The second main networker can be used or not, depending on the specific situation. When using two main networkers to network the filament bundle, the special irregular cross-section with "hooks" on the filament bundle cross-section can further increase the number of network points of the filament bundle, thereby improving the cohesion of the filament bundle.

[0072] In this embodiment, the produced fiber specification is FDY40D05F, and the fiber breaking strength is 7.5 cN / dtex. The number of fiber bundle network points is 7 per meter.

[0073] Example 3 (Reference) Figures 1 to 7

[0074] A method for preparing low-pore-number, high-cohesion, high-strength nylon 6, comprising the following steps:

[0075] (1) Nylon 6 chips with a moisture content of 445 ppm are fed into a screw extruder through a hopper for extrusion. The melt temperature in the screw extruder is set to 275°C. The melt extruded from the screw extruder is transported to a spinning metering pump through a melt pipeline, and then quantitatively delivered to the spinning assembly by the metering pump. Due to the action of the metal grit and nonwoven fabric in the spinning assembly, the polymer melt forms high pressure at the spinning assembly, which allows it to be ejected from the spinneret to form fibers. The radial cross-section of the fibers is provided with a number of hooks 1a spaced along the circumferential direction.

[0076] (2) The ejected fiber 1 passes through the slow cooler in sequence. The temperature of the slow cooler is 265℃. Its main function is to allow the fiber to cool slowly after it is ejected from the spinneret. This provides more time for the macromolecular chains in the fiber to move in orientation, thereby improving the strength of the fiber.

[0077] (3) Then, the smoke is drawn through a single-unit suction device. The pressure at the smoke suction point is 0.29 barr. The smoke suction is to remove the single-unit generated at the spinneret to prevent it from adhering to the spinneret surface or the fiber and affecting the stability of the spinning production. Then, the fiber bundle is formed by uniform cooling by side blowing. The side blowing wind speed is 0.57 m / s and the wind temperature is 23℃. Its function is to uniformly cool the fiber bundle so that it has a certain strength to be drawn.

[0078] (4) Then the filament bundle is fed into the spinning bundle enhancement oiling device with oil nozzle 30, guide hook 50 and air blower bundle 60. All the monofilaments sprayed from a spinneret are divided into several strands and oiled by the oil nozzles respectively. Then each strand passes through the guide hook under the corresponding oil nozzle. Finally, the strands enter the air blower bundle together and are hooked together by compressed air.

[0079] (5) The oiled bundles are sent to the pre-networker through the spinning tunnel. The pressure of the pre-networker is 0.095 MPa. Its main function is to blow the oil on the bundles evenly, which is beneficial to the product performance and production stability. In addition, it also has the function of networking the bundles.

[0080] (6) Then the filament bundle is stretched and shaped by the first and second rollers. The speeds of the first and second rollers are 1750 m / min and 4980 m / min, respectively, and the temperature of the second roller is 190°C. The first and second rollers mainly play a stretching role on the filament bundle, so that the filament bundle has a certain strength. The temperature of the second roller can provide the energy required for the molecular chains in the filament bundle to move in the direction of the force under the action of the stretching force. The so-called thermal stretching prevents the filament bundle from breaking or producing fuzz under high speed and high stretching ratio.

[0081] (7) The filament bundle is disturbed by the main networker. The pressure of the main networker is 0.65 MPa. Compressed air is used to disturb the filament bundle, thereby networking the filament bundle and improving its cohesion. Because low-pore-count (F-number less than 10) high-strength nylon 6 has high strength, and the higher the strength, the harder the fiber, these two factors make it difficult for low-pore-count high-strength nylon 6 to form network points. Therefore, this invention uses a main networker to network the filament bundle, combined with a special irregular cross-section with "hooks" on the filament bundle cross-section, so that the number of network points of low-pore-count high-strength nylon 6 is significantly higher than that of high-strength nylon 6 with a circular uniform cross-section.

[0082] (8) After the spinning tension is adjusted by the guide disc, the yarn is wound into a cake at the winding head. The speed of the guide disc is 4950 m / min, and the winding speed of the winding head is 4900 m / min.

[0083] In this embodiment, to ensure that the spun fibers can hook together after being agitated by the air pressure of the spinning device, making them less prone to separation under external force and improving the cohesion of the fiber bundle, the spinning assembly is equipped with a spinneret 10. The spinneret is provided with a plurality of spinneret holes 11 of the same shape and size, spaced apart. The spinneret holes are shaped like arrows, arranged at least three times outwards along the circumferential direction, with the other ends of the arrows connected and identical. This results in hooked sections on the extruded spun fibers, improving the cohesion of the fiber bundle.

[0084] In this embodiment, the spinning bundle reinforcement oiling device includes an oil nozzle frame 20, on which at least three oil nozzles 30 for spinning oiling are installed at intervals. A guide hook frame 40 is located below the oil nozzle frame, on which guide hooks 50, corresponding to the number of oil nozzles and used for guiding the yarn, are installed at intervals. A blower bundler frame is located below the guide hook frame, on which blower bundlers 60 are installed for the yarn to pass through and bundle together. This ensures that multiple yarn bundles are hooked together after passing through the spinning bundle reinforcement oiling device.

[0085] In this embodiment, for better installation of the nozzle, the nozzle holder includes a main oil supply pipe 21 connected to the oil supply pipe. A retaining ring 22 is provided at the other end of the main oil supply pipe, and branch oil supply pipes 23 are installed at intervals on the retaining ring. The nozzle is installed at the other end of the branch oil supply pipes. The nozzle has a vertically arranged through groove 31 for the filament to pass through, and an oil spray nozzle 32 communicating with the branch oil supply pipes. The nozzle is made of ceramic.

[0086] In this embodiment, to facilitate the installation of the guide hook, the guide hook frame includes a fixing rod 41, with a connecting ring 42 fixed to the other end of the fixing rod. Guide hooks 50 are installed at intervals along the circumferential direction via the connecting rod 43 on the connecting ring. For convenient spinning guidance and installation, the guide hook is spiral-shaped, with a through hole 51 in the middle for the spinning yarn to pass through, and a spinning inlet 52 leading into the through hole. The guide hook is made of ceramic.

[0087] In this embodiment, to achieve the bundling of several strands of spun yarn into one by air pressure, the air-blowing bundler includes an air guide pipe 61. One end of the air guide pipe is connected to a compressed air pipe, and a switch for controlling the compressed air pressure is provided on the compressed air pipe. The other end of the air guide pipe is provided with a bundling hole 62 for the spun yarn to pass through. An arc-shaped air blowing channel 63 is provided on the air guide pipe leading into the bundling hole. The width of the arc-shaped air blowing channel gradually narrows from the air guide pipe towards the bundling hole, thereby allowing the incoming air to be compressed again. Furthermore, the outlet direction of the arc-shaped air blowing channel is tangent to the side wall of the bundling hole, so that the compressed air blows around the bundling hole in one direction, causing the spun yarn to rotate and wind in the direction of rotation of the compressed air within the bundling hole. An arc-shaped mounting channel 64, communicating with the bundling hole, is also provided on the outside of the bundling hole for mounting the spun yarn, so that the spun yarn can be installed into the bundling hole.

[0088] In this embodiment, the air-blowing cluster is made of ceramic, and the diameter of the clustering hole is 0.5~1.5cm, and the height of the clustering hole is 1-2cm. During operation, the air pressure of the air-blowing cluster is 0.03~0.15MPa.

[0089] Since the compressed air is blown in one direction around the bundling hole, the filament bundles will rotate and intertwine with each other at the bundling hole. Because the cross-section of the filament bundle has a hook structure, the filament bundles between each other will hook together during this process, thereby enhancing the cohesion between the filament bundles.

[0090] In this embodiment, the slow cooler, the single-unit suction device, and the side blower are arranged between the spinneret and the nozzle holder.

[0091] In this embodiment, in step (7), two main networkers are set up, namely a first main networker and a second main networker, and the pressure of both the first and second main networkers is 0.73 MPa. The second main networker can be used or not, depending on the specific situation. When using two main networkers to network the filament bundle, the special irregular cross-section with "hooks" on the filament bundle cross-section can further increase the number of network points of the filament bundle, thereby improving the cohesion of the filament bundle.

[0092] In this embodiment, the produced fiber specification is FDY70D08F, and the fiber breaking strength is 7.2 cN / dtex. The number of fiber bundle network points is 12 per meter.

[0093] The above description is only a preferred embodiment of the present invention. For those skilled in the art, according to the teachings of the present invention, designing different forms of preparation methods for low-pore-count, high-cohesion, and high-strength nylon 6 does not require creative labor. All equivalent changes, modifications, substitutions, and variations made in accordance with the scope of the patent application of the present invention without departing from the principles and spirit of the present invention shall be covered by the present invention.

Claims

1. A method for preparing low-pore-count, high-cohesion, high-strength nylon 6, characterized in that, The steps are as follows: (1) Nylon 6 chips with a moisture content of 350-450ppm are extruded through a screw extruder and quantitatively transported to the spinning assembly by a metering pump to form fibers. The radial cross section of the fibers is provided with a number of hooks at intervals along the circumferential direction. The set temperature of the screw extruder is 255-280℃. The spinning assembly is provided with a spinneret. The spinneret is provided with a number of spinnerets of the same shape and size at intervals. The spinnerets are composed of at least three arrow-shaped structures arranged at intervals along the circumferential direction, with the other ends of the arrows connected and identical. (2) The ejected fibers pass through a slow cooler and a single-unit suction device in sequence, and are then cooled evenly by side blowing air; (3) Then the filament bundle is fed into a spinning bundle reinforcement oiling device with an oil nozzle, a guide hook, and a blower bundle. All the monofilaments ejected from a spinneret are divided into several bundles, which are oiled by the oil nozzles and the corresponding guide hooks. Finally, the bundles enter the blower bundle together and are hooked together by compressed air. The spinning bundle reinforcement oiling device includes an oil nozzle frame, on which at least three oil nozzles for spinning oiling are installed at intervals. A guide hook frame is set on the lower side of the oil nozzle frame, on which guide hooks corresponding to the number of oil nozzles and used for guiding the filaments are installed at intervals. A blower bundler frame is located below the guide hook frame. The blower bundler frame is equipped with a blower bundler for the spinning yarn to pass through and bundle the yarn. The blower bundler includes an air guide pipe, one end of which is connected to a compressed air pipe, and a switch for controlling the compressed air pressure is provided on the compressed air pipe. The other end of the air guide pipe has a bundling hole, and an arc-shaped blowing channel is provided on the air guide pipe leading into the bundling hole. The outlet direction of the arc-shaped blowing channel is tangent to the side wall of the bundling hole. An arc-shaped mounting channel communicating with the bundling hole for installing the spinning yarn is also provided outside the bundling hole. (4) The oiled bundles are sent to the pre-networker to blow the oil evenly on the bundles, and then they are drawn and shaped by the first and second rollers, and the main networker disturbs the upper network to improve the cohesion of the bundles; a first main networker and a second main networker are provided. (5) After the spinning tension is adjusted by the guide plate, the yarn is wound into a yarn cake at the winding head.

2. The method for preparing a low-pore-count, high-cohesion, high-strength nylon 6 according to claim 1, characterized in that, In step (2), the temperature of the slow cooler is 230-270℃; the pressure at the smoke extraction point of the single extraction device is 0.1-0.3 barr; the wind speed of the side blowing is 0.3-0.6 m / s, and the wind temperature is 19-23℃.

3. The method for preparing a low-pore-count, high-cohesion, high-strength nylon 6 according to claim 1, characterized in that, The nozzle holder includes a main oil supply pipe connected to the oil supply pipe, a fixing ring at the other end of the main oil supply pipe, and oil supply branch pipes installed at intervals on the fixing ring. The nozzle is installed at the other end of the oil supply branch pipe. The nozzle is vertically provided with a through groove for the filament bundle to pass through, and is provided with an oil spray port connected to the oil supply branch pipe.

4. The method for preparing a low-pore-count, high-cohesion, high-strength nylon 6 according to claim 1, characterized in that, In step (4), the pressure of the pre-networker is 0.05-0.1 MPa; the speeds of the first and second rollers are 1200-2000 m / min and 3600-5000 m / min, respectively, and the temperature of the second roller is 140-205℃; the pressure of the main networker is 0.45-0.75 MPa.

5. A method for preparing a low-pore-count, high-cohesion, high-strength nylon 6 according to claim 1, 3, or 4, characterized in that, In step (4), the pressure of the first master networker and the second master networker is 0.45-0.75MPa.

6. The method for preparing a low-pore-count, high-cohesion, high-strength nylon 6 according to claim 1, characterized in that, In step (5), the speed of the guide disc is 3500-4960 m / min, and the winding speed of the winding head is 3400-4900 m / min.

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