Process and apparatus for dry spinning uhmwpe fibers

Abstract

This invention relates to the field of dry spinning technology, specifically to a method and apparatus for preparing UHMWPE fibers by dry spinning. The method includes: spinning UHMWPE gel to obtain several filament bundles; feeding the filament bundles into an annular channel for stretching; providing several air inlets in the inner central air duct of the channel, with slits on the duct wall; simultaneously with the stretching process, air from the air inlets is blown through the slits into the channel to provide airflow to the filament bundles; performing bundle-gathering, drawing, setting, and winding processes on the stretched filament bundles to obtain UHMWPE fiber precursors; and then performing post-spinning processes on the precursors to obtain UHMWPE fibers. The method provided by this invention can significantly reduce the impact of channel airflow on the evenness of the finished fiber during dry spinning, effectively improving the fineness uniformity of UHMWPE fibers prepared by dry spinning.

Description

Technical Field

[0001] This invention relates to the field of dry spinning technology, and specifically to a method and apparatus for preparing UHMWPE fibers by dry spinning. Background Technology

[0002] Internationally, there are two major brands in the production of ultra-high molecular weight polyethylene (UHMWPE) fibers: (DSM Netherlands) and (Honeywell, Inc., USA) represents two different production process technology routes: with The dry process, represented by [example name], uses a highly volatile decahydronaphthalene solvent to prepare ultra-high molecular weight polyethylene spinning solution. After the spinning solution is extruded from the spinneret, the decahydronaphthalene vaporizes and escapes, yielding dry gel-like fibers. These fibers are then subjected to high-ratio stretching to obtain high-strength, high-modulus polyethylene fibers. This is referred to as the dry process. The wet process, represented by [example of wet process], uses low-volatile solvents (mineral oil, white oil, etc.) to prepare ultra-high molecular weight polyethylene spinning dope. After extrusion from the spinneret, the spinning dope is coagulated in a water bath (or a mixed bath of water and ethylene glycol, etc.) to obtain wet gel fiber containing the low-volatile solvent. This wet gel fiber is then subjected to multi-stage extraction using a high-volatile extractant and a continuous extraction device to displace the low-volatile solvent, yielding the gel fiber (the mixture of extractant, solvent, and water is collected and sent to a distillation unit for separation and recovery). The extractant in the gel fiber undergoes continuous multi-stage drying to fully vaporize and escape, resulting in dry gel fiber. This dry gel fiber is then subjected to high-strength, high-modulus polyethylene fiber. This process is referred to as the wet process.

[0003] The domestic high-performance polyethylene fiber industry has developed rapidly over the past two decades, forming two main technological routes: the wet process developed by Donghua University and the dry process jointly developed by the China Textile Academy and the Nanjing Chemical Industry Research Institute. The wet process technology was industrialized earlier, with over a dozen companies in China, including Beijing Tongyi, Hunan Zhongtai, Zhejiang Dacheng, Shandong Aidi, and Beijing Weiya, already in operation. The dry process technology came later. In 2008, Yizheng Chemical Fiber (utilizing the first-generation product technology from this project in cooperation with the Nanjing Chemical Industry Research Institute) completed and put into operation the first 300t / a high-performance polyethylene fiber industrial plant in China, currently boasting a capacity of 3,300 tons. It is also the only company in China using the dry spinning method to produce ultra-high molecular weight polyethylene fiber.

[0004] In the large-scale pilot and industrial-scale implementation of dry spinning, the entire process from the spinneret outlet to the guide roller, after the prepared and pre-swollen gel raw material solution is the fiber head stretching, which is also the most crucial process in dry spinning. The quality of the fiber bundle formation directly determines the subsequent drafting process and the product performance indicators of the fiber. First, after the raw material solution is extruded through the spinneret, the volatile solvent decahydronaphthalene in the solution vaporizes at high temperature and exchanges heat with the side-blowing air and duct air below the spinneret. The vapor is then carried into the recovery system by the side-blowing air and duct air, thereby achieving the purpose of solvent removal and forming gel filaments. The fiber bundle is stretched in a 4-8 meter duct. Even with the adjustment of air temperature and speed within the duct, the fiber bundle is inevitably disturbed by the duct air, affecting the uniformity of fiber formation and other physical properties.

[0005] This invention provides a method and equipment for improving the performance of UHMWPE fibers prepared by dry spinning. Based on existing spinning technology, it greatly reduces the influence of tunnel air on the unevenness of finished fibers during dry spinning, and effectively improves the fineness uniformity of UHMWPE fibers prepared by dry spinning. Summary of the Invention

[0006] The purpose of this invention is to overcome the problem of uniformity in the formation of dry-spun fibers in the prior art, and to provide a method and apparatus for preparing UHMWPE fibers by dry spinning.

[0007] To achieve the above objectives, the first aspect of the present invention provides a method for preparing UHMWPE fibers by dry spinning, the method comprising: spinning UHMWPE gel to obtain several filament bundles, feeding the filament bundles into an annular channel for stretching, and providing several air outlets in the inner central air duct of the channel, and providing slits on the wall of the inner central air duct.

[0008] During the stretching process, air from the air outlet is blown through the slit into the channel to supply air to the filament bundle. The stretched filament bundle is then subjected to bundling, stretching, shaping, and winding processes to obtain UHMWPE fiber filaments. The fiber filaments are then subjected to post-spinning processes to obtain UHMWPE fibers.

[0009] A second aspect of the present invention provides an apparatus for dry spinning to prepare UHMWPE fibers, the apparatus comprising a channel, wherein a spinneret is provided at the upper part of the channel for spinning UHMWPE gel to obtain several fiber bundles;

[0010] The channel includes an outer annular channel and an inner central air duct. The inner central air duct has several slits on its wall to connect it to the outer annular channel. The outer annular channel is used to stretch the filament bundle.

[0011] Along the direction away from the spinneret, the tunnel is sequentially provided with a first tunnel air outlet, a second tunnel air outlet, a first air supply pipe, a second air supply pipe, and a third air supply pipe;

[0012] The first and second air outlets of the tunnel are arranged opposite to each other and are respectively connected to the tunnel.

[0013] The first air supply pipe, the second air supply pipe, and the third air supply pipe pass through the outer ring annular channel and enter the inner ring central air supply pipe. The air supplied by the first air supply pipe, the second air supply pipe, and the third air supply pipe blows through the slit in the wall of the inner ring central air supply pipe toward the outer ring annular channel to supply air to the filament bundle, and exhausts the air through the air outlet of the first channel and the air outlet of the second channel.

[0014] The lower part of the channel is provided with guide rollers at intervals. The central axis of the channel is tangent to the outer ring of the guide rollers. The guide rollers are used to bundle the stretched filaments together.

[0015] Through the above technical solutions, the method and apparatus for preparing UHMWPE fibers by dry spinning provided by the present invention have the following beneficial effects:

[0016] The method provided by this invention can reduce the disturbance of the fiber bundle by the tunnel air during dry spinning, reduce the unevenness of the finished fiber and the impact of fiber breakage during the stretching process, effectively improve the fineness uniformity of UHMWPE fiber prepared by dry spinning, and further reduce the moisture content of the fiber filament, thereby improving the mechanical properties of the finished fiber. Attached Figure Description

[0017] Figure 1 This invention provides a preferred embodiment of an apparatus for dry spinning to prepare UHMWPE fibers;

[0018] Figure 2 This is a traditional apparatus used in Comparative Examples 1-2 for the dry spinning preparation of UHMWPE fibers.

[0019] Explanation of reference numerals in the attached figures

[0020] 1. Passageway 2. Spinneret 21. Top view of the spinneret

[0021] 3. Outer ring-shaped duct; 4. Inner ring central air duct.

[0022] 41. Partial schematic diagram of the inner central duct wall. 42. Schematic diagram of the narrow slit in the inner central duct wall.

[0023] 5. First tunnel air outlet; 6. Second tunnel air outlet; 7. First air supply duct.

[0024] 8. Second air supply duct; 9. Third air supply duct; 10. Guide roller.

[0025] 11. End cap; 12. Side air inlet; 13. Side air outlet.

[0026] 14. Duct air inlet 15. Duct air outlet 16. Nitrogen blanketing

[0027] 17. Standard spinneret 18. Side-blowing air box 19. Standard tunnel Detailed Implementation

[0028] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0029] The first aspect of the present invention provides a method for preparing UHMWPE fibers by dry spinning, the method comprising: spinning UHMWPE gel to obtain several filament bundles, feeding the filament bundles into an annular channel for stretching, and providing several air outlets in the inner central air duct of the channel, and providing slits on the wall of the inner central air duct.

[0030] During the stretching process, air from the air outlet is blown through the slit into the channel to supply air to the filament bundle. The stretched filament bundle is then subjected to bundling, stretching, shaping, and winding processes to obtain UHMWPE fiber filaments. The fiber filaments are then subjected to post-spinning processes to obtain UHMWPE fibers.

[0031] In this invention, the filament bundle is stretched in an annular channel on the outer ring, which can reduce the disturbance of the filament bundle by the channel air during dry spinning, reduce the impact on the evenness of the finished fiber and the fiber breakage during the stretching process, effectively improve the fineness uniformity of the UHMWPE fiber prepared by dry spinning, and the UHMWPE fiber obtained has excellent evenness performance, and also improves the relevant mechanical properties such as breaking strength, breaking modulus, strength variation rate CV, and elongation variation rate CV.

[0032] In a preferred embodiment of the present invention, the gel extrusion rate of the spinneret is 2-10 m / min, preferably 3-6 m / min.

[0033] In a preferred embodiment of the present invention, along the fiber stretching direction, a first air outlet, a second air outlet, and a third air outlet are sequentially arranged in the inner ring central air duct.

[0034] In a preferred embodiment of the present invention, the air supply temperature of the first air outlet is 10-160°C, preferably 90-130°C.

[0035] In a preferred embodiment of the present invention, the air supply temperature of the second air outlet is 10-160°C, preferably 50-90°C.

[0036] In a preferred embodiment of the present invention, the air supply temperature of the third air outlet is 10-160°C, preferably 10-50°C.

[0037] In a preferred embodiment of the present invention, the air supply pressure of the first air outlet, the second air outlet, and the third air outlet is each independently 10-400 kPaG, preferably 100-200 kPaG.

[0038] In this invention, based on the solvent content in the fiber bundle and the amount of heat exchange at different locations in the channel, three air outlets with different temperatures are sequentially set in the inner central air duct. This allows for the efficient recovery of the solvent evaporated in the channel, resulting in fiber filaments with low moisture content. Simultaneously, it can further improve the breaking strength and breaking modulus of UHMWPE fibers, reduce the variability in strength (CV), variability in elongation (CV), and evenness of UHMWPE fibers, and reduce the number of fiber breaks per 100 meters.

[0039] In a preferred embodiment of the present invention, the method for preparing the UHMWPE gel includes:

[0040] After UHWMPE resin, sodium stearate, and antioxidant are mixed evenly, the mixture is placed into a swelling vessel containing preheated decahydronaphthalene solvent. The external heating of the swelling vessel is turned on and the inside of the swelling vessel is stirred to carry out the swelling treatment. The resulting liquid is transferred to a homogenizing vessel, and the inside of the homogenizing vessel is stirred to carry out the homogenization treatment at room temperature. Then the resulting liquid is transferred to a twin-screw extruder (the temperature settings of the seven zones of the twin-screw extruder are 85℃-120℃-155℃-165℃-165℃-170℃-165℃) for further swelling, dissolution, shearing, degassing and back-mixing treatment to obtain UHWMPE gel.

[0041] The antioxidant is selected from at least one of antioxidant BHT, antioxidant 1076, and antioxidant 1010; the viscosity-average molecular weight of the UHWMPE resin is 4.5-5.8 million; the mass ratio of UHWMPE resin, sodium stearate, antioxidant, and decahydronaphthalene solvent is 140-150:1-1.15:1:1800-1900; the preheating temperature is 95-98℃; the swelling time is 2.5-4 hours; and the homogenization time is 3-24 hours.

[0042] The second aspect of the present invention provides an apparatus for dry spinning to prepare UHMWPE fibers, the apparatus comprising a channel 1, wherein a spinneret 2 is provided on the upper part of the channel 1 for spinning UHMWPE gel to obtain several filament bundles;

[0043] The passageway 1 includes an outer annular passageway 3 and an inner central air duct 4. The inner central air duct 4 has several slits on its wall to connect the inner central air duct 4 and the outer annular passageway 3. The outer annular passageway 3 is used to stretch the filament bundle.

[0044] Along the direction away from the spinneret 2, the tunnel 1 is sequentially provided with a first tunnel air outlet 5, a second tunnel air outlet 6, a first air supply pipe 7, a second air supply pipe 8, and a third air supply pipe 9;

[0045] The first tunnel air outlet 5 and the second tunnel air outlet 6 are arranged opposite to each other and are respectively connected to the tunnel 1;

[0046] The first air supply pipe 7, the second air supply pipe 8, and the third air supply pipe 9 pass through the outer ring annular channel 3 and enter the inner ring central air supply pipe 4. The air supplied by the first air supply pipe 7, the second air supply pipe 8, and the third air supply pipe 9 is blown through the slits in the wall of the inner ring central air supply pipe 4 to the outer ring annular channel 3 to supply air to the filament bundle, and is exhausted through the first channel air outlet 5 and the second channel air outlet 6.

[0047] The lower part of the channel 1 is provided with guide rollers 10 at intervals. The central axis of the channel 1 is tangent to the outer ring of the guide rollers 10. The guide rollers 10 are used to bundle the stretched filaments.

[0048] In a preferred embodiment of the present invention, the openable portion of the spinneret 2 is an annular shape with a notch. The openable portion of the spinneret 2 is correspondingly arranged with the outer annular channel 3. The projection of the notch portion on the horizontal plane coincides with the projection of the portions of the first air supply pipe 7, the second air supply pipe 8, and the third air supply pipe 9 passing through the outer annular channel 3 on the horizontal plane, so as to ensure that all the filaments obtained by the spinneret 2 after the spinning process can be stretched in the outer annular channel 3.

[0049] In a preferred embodiment of the present invention, the ratio of the area of ​​the perforated portion of the spinneret 2 to the cross-sectional area of ​​the inner central duct 4 is 1:0.3-0.5.

[0050] In a preferred embodiment of the present invention, the openings of the first air supply pipe 7, the second air supply pipe 8 and the third air supply pipe 9 are located at the central axis of the passageway 1 and the opening direction is vertically upward.

[0051] In a preferred embodiment of the present invention, a cap 11 is provided at the bottom of the inner ring central air duct 4.

[0052] In a preferred embodiment of the present invention, the slit is a rounded rectangle, and the ratio of the total height of the slit to the diameter of the cross-section of the inner ring central duct 4 is 1:1.25-1.3.

[0053] In a preferred embodiment of the present invention, the ratio of the total height of the slit to the width of the slit is 1:0.05-0.1.

[0054] In a preferred embodiment of the present invention, the total area of ​​the slit accounts for 25-45% of the wall area of ​​the inner central duct 4.

[0055] In a preferred embodiment of the present invention, the method for preparing UHMWPE fibers by dry spinning provided by the present invention is as follows: Figure 1 The process is carried out in the apparatus shown, and the specific procedure is as follows:

[0056] The air supply temperature of the first air supply duct 7 is set to 90-130℃, the air supply temperature of the second air supply duct 8 is set to 50-90℃, and the air supply temperature of the third air supply duct 9 is set to 10-50℃. The air supply pressure of the first air supply duct 7, the second air supply duct 8, and the third air supply duct 9 is independently set to 100-200KPaG. The UHMWPE gel is sequentially fed into the spinneret 2 through a booster pump and a metering pump for spinnereting to obtain several filament bundles. The filament bundles are then stretched in the outer annular channel 3. The metering pump has a rotation speed of 18-30Hz, the gel extrusion rate of the spinneret is 3-6m / min, the perforated part of the spinneret 2 is a notched annular shape, the perforated part of the spinneret 2 is correspondingly arranged with the outer annular channel 3, the ratio of the area of ​​the perforated part of the spinneret 2 to the cross-sectional area of ​​the inner central air duct 4 is 1:0.3-0.5, and the spinneret 2 is provided with 280-420 holes with a diameter of 0.5-0.85mm;

[0057] During the stretching process, the air supplied by the first air supply pipe 7, the second air supply pipe 8 and the third air supply pipe 9 is blown through the slit in the wall of the inner ring central air supply pipe 4 to the outer ring annular channel 3 to supply air to the filament bundle, and is exhausted through the first channel outlet 5 and the second channel outlet 6.

[0058] The slit is a rounded rectangle, the ratio of the total height of the slit to the diameter of the cross-section of the inner central duct 4 is 1:1.25-1.3, the ratio of the total height of the slit to the width of the slit is 1:0.05-0.1, and the total area of ​​the slit accounts for 25-45% of the wall area of ​​the inner central duct 4.

[0059] After being bundled by the guide roller 10, the stretched filaments are fed into a five-roller drawing machine, a setting box, and a winding machine for sequential drawing, setting, and winding to obtain UHMWPE fiber filaments.

[0060] The UHMWPE fiber precursor was kept in a static environment for 24-48 hours and then subjected to post-spinning treatment to obtain UHMWPE fiber.

[0061] The post-spinning process includes: subjecting UHMWPE fiber filaments to high-ratio stretching under the following conditions: first-stage hot stretching at 140±1℃ at 5-10 times the temperature, second-stage hot stretching at 144±1℃ at 2-5 times the temperature, and third-stage hot stretching at 147±1℃ at 1-2 times the temperature; then feeding the high-ratio stretched UHMWPE fiber filaments into a winding machine for winding to obtain UHMWPE fibers.

[0062] The present invention will be described in detail below through examples. In the following examples and comparative examples, the relevant data were measured after the device was running stably for 4-12 hours under the set process parameters. The method for determining the wet content of the precursor fiber is as follows: 10 samples were randomly selected from the prepared UHMWPE fiber precursor fiber to determine the wet content of the precursor fiber (i.e., the solvent concentration in the precursor fiber), and the average value was taken.

[0063] The method for determining the mechanical properties is as follows: 15 samples are randomly selected from the prepared UHMWPE fiber and tested 10 times on an Instron universal drawing machine. The average value is taken to obtain the mechanical properties of the UHMWPE fiber, including breaking strength, breaking modulus, strength variation rate CV, and elongation variation rate CV.

[0064] Evenness: The evenness of UHMWPE fiber was determined according to GB / T 14346-1993, the electronic test method for evenness of chemical fiber filament.

[0065] 100-meter breakage: Ten samples were randomly selected from the prepared UHMWPE fiber. After accurately cutting 100 meters using a yarn length measuring machine, the number of broken ends and fuzzes on the fiber surface were observed evenly through a self-made incandescent lamp and reflector, and the average value was taken.

[0066] Preparation Example 1 is used to illustrate the preparation of UHMWPE gel.

[0067] Preparation Example 1

[0068] After UHWMPE resin, sodium stearate, and antioxidant are mixed evenly, the mixture is placed into a swelling vessel containing preheated decahydronaphthalene solvent. The external heating of the swelling vessel is turned on and the inside of the swelling vessel is stirred to carry out the swelling treatment. The resulting liquid is transferred to a homogenizing vessel, and the inside of the homogenizing vessel is stirred to carry out the homogenization treatment at room temperature. Then the resulting liquid is transferred to a twin-screw extruder (the temperature settings of the seven zones of the twin-screw extruder are 85℃-120℃-155℃-165℃-165℃-170℃-165℃) for further swelling, dissolution, shearing, degassing and back-mixing treatment to obtain UHWMPE gel.

[0069] The antioxidant is antioxidant 1010, the viscosity-average molecular weight of the UHWMPE resin is 4.5 million, the mass ratio of UHWMPE resin, sodium stearate, antioxidant, and decahydronaphthalene solvent is 143:1.15:1:1900, the preheating temperature is 98°C, the swelling time is 3 hours, and the homogenization time is 4 hours.

[0070] Examples 1-6 and Comparative Examples 1-2 all used the UHMWPE gel prepared in Preparation Example 1.

[0071] Example 1

[0072] like Figure 1 As shown, the air supply temperature of the first air supply duct 7 is set to 99-101℃, the air supply temperature of the second air supply duct 8 is set to 59-61℃, and the air supply temperature of the third air supply duct 9 is set to 14-16℃. The air supply pressure of the first air supply duct 7, the second air supply duct 8, and the third air supply duct 9 is 150 kPaG. The UHMWPE gel is sequentially fed into the spinneret 2 through a booster pump and a metering pump for spinning, resulting in several filament bundles. These filament bundles are then processed in the outer annular channel 3. Stretching process; wherein, the metering pump rotates at 20 Hz, the gel extrusion rate of the spinneret is 3.25 m / min, the perforated portion of the spinneret 2 is a notched annular shape, the perforated portion of the spinneret 2 is correspondingly arranged with the outer annular channel 3, the ratio of the area of ​​the perforated portion of the spinneret 2 to the cross-sectional area of ​​the inner central air duct 4 is 2:1, and the spinneret 2 is provided with 320 holes with a diameter of 0.75 mm;

[0073] During the stretching process, the air supplied by the first air supply pipe 7, the second air supply pipe 8 and the third air supply pipe 9 is blown through the slit in the wall of the inner ring central air supply pipe 4 to the outer ring annular channel 3 to supply air to the filament bundle, and is exhausted through the first channel air outlet 5 and the second channel air outlet 6.

[0074] The slit is a rounded rectangle, the ratio of the total height of the slit to the diameter of the cross-section of the inner central duct 4 is 1:1.25, the ratio of the total height of the slit to the width of the slit is 10:1, and the total area of ​​the slit accounts for 35% of the wall area of ​​the inner central duct 4.

[0075] After being bundled by the guide roller 10, the stretched filaments are fed into the five-roller drawing machine, the shaping hot box and the winding machine for stretching, shaping and winding in sequence to obtain UHMWPE fiber filaments. The moisture content of the UHMWPE fiber filaments is measured by sampling and the results are shown in Table 1.

[0076] The UHMWPE fiber filaments were kept in a static environment for 24 hours and then subjected to post-spinning treatment to obtain UHMWPE fibers.

[0077] The post-spinning process includes: subjecting UHMWPE fiber filaments to high-ratio stretching under the following conditions: first-stage hot stretching at 140±1℃ at 5-10 times the temperature, second-stage hot stretching at 144±1℃ at 2-5 times the temperature, and third-stage hot stretching at 147±1℃ at 1-2 times the temperature; then feeding the high-ratio stretched UHMWPE fiber filaments into a winding machine for winding to obtain UHMWPE fibers, and taking samples to test the evenness rate, number of breaks per 100 meters, and related mechanical properties of the UHMWPE fibers. The results are shown in Table 1.

[0078] Example 2

[0079] The same method as in Example 1 is used, except that the air supply temperature of the first air supply pipe 7 is set to 119-121℃, the air supply temperature of the second air supply pipe 8 is set to 79-81℃, and the air supply temperature of the third air supply pipe 9 is set to 29-31℃. The air supply pressure of the first air supply pipe 7, the second air supply pipe 8, and the third air supply pipe 9 is 300kPaG. The rotation speed of the metering pump is 25Hz, and the extrusion rate of the gel in the spinneret process is 4m / min.

[0080] Example 3

[0081] The same method as in Example 1 is used, except that the air supply temperature of the first air supply pipe 7 is set to 119-121℃, the air supply temperature of the second air supply pipe 8 is set to 69-71℃, and the air supply temperature of the third air supply pipe 9 is set to 19-21℃. The air supply pressure of the first air supply pipe 7, the second air supply pipe 8, and the third air supply pipe 9 is 200 kPaG. The rotation speed of the metering pump is 22 Hz, and the extrusion rate of the gel in the spinneret process is 3.58 m / min.

[0082] Example 4

[0083] The same method as in Example 1 is used, except that the air supply temperature of the first air supply pipe 7 is set to 128-130℃, the air supply temperature of the second air supply pipe 8 is set to 88-90℃, and the air supply temperature of the third air supply pipe 9 is set to 39-41℃. The air supply pressure of the first air supply pipe 7, the second air supply pipe 8, and the third air supply pipe 9 is 350 kPaG. The rotation speed of the metering pump is 27 Hz, and the extrusion rate of the gel in the spinneret process is 4.38 m / min.

[0084] Example 5

[0085] The same method as in Example 1 is used, except that the air supply temperature of the first air supply pipe 7 is set to 90-92℃, the air supply temperature of the second air supply pipe 8 is set to 50-52℃, and the air supply temperature of the third air supply pipe 9 is set to 10-12℃. The air supply pressure of the first air supply pipe 7, the second air supply pipe 8, and the third air supply pipe 9 is 100kPaG. The rotation speed of the metering pump is 18Hz, and the extrusion rate of the gel in the spinneret process is 3m / min.

[0086] Example 6

[0087] The same method as in Example 1 is used, except that the air supply temperature of the third air supply duct 9 is set to 59-61℃.

[0088] Comparative Examples 1-2 Figure 2 The apparatus shown is used to prepare UHMWPE fibers.

[0089] Comparative Example 1

[0090] like Figure 2As shown, the side-blowing air inlet 12 is set with an air temperature of 99-101℃, the side-outlet air pressure is 150KPaG, the tunnel air inlet 14 is set with an air temperature of 59-61℃, the tunnel air outlet 15 is set with a pressure of 150KPaG, and the nitrogen sealing 16 near the filament outlet is at room temperature and pressure of 155KPaG. The UHMWPE gel is sequentially fed through a booster pump and a metering pump into a conventional spinneret 17 for spinning to obtain several filament bundles. The filament bundles are then stretched in a conventional tunnel 19 after entering the side-blowing air box 18. The metering pump rotates at 20Hz, the extrusion rate of the spinned gel is 3.25m / min, the openable portion of the conventional spinneret 17 is circular, and the conventional spinneret 17 has 300 holes with a diameter of 0.75mm.

[0091] After being bundled by the guide roller 10, the stretched filaments are fed into the five-roller drawing machine, the shaping hot box and the winding machine for stretching, shaping and winding in sequence to obtain UHMWPE fiber filaments. The moisture content of the UHMWPE fiber filaments is measured by sampling and the results are shown in Table 1.

[0092] The UHMWPE fiber filaments were kept in a static environment for 24 hours and then subjected to post-spinning treatment to obtain UHMWPE fibers.

[0093] The post-spinning process includes: subjecting UHMWPE fiber filaments to high-ratio stretching under the following conditions: first-stage hot stretching at 140±1℃ at 5-10 times the temperature, second-stage hot stretching at 144±1℃ at 2-5 times the temperature, and third-stage hot stretching at 147±1℃ at 1-2 times the temperature; then feeding the high-ratio stretched UHMWPE fiber filaments into a winding machine for winding to obtain UHMWPE fibers, and taking samples to test the evenness rate, number of breaks per 100 meters, and related mechanical properties of the UHMWPE fibers. The results are shown in Table 1.

[0094] Comparative Example 2

[0095] The same method as Comparative Example 1 was used, except that the side blowing air inlet 12 was set to a supply air temperature of 109-111℃, the duct air inlet 14 was set to a supply air temperature of 69-71℃, the metering pump speed was 22Hz, and the gel extrusion rate of the spinneret was 3.57m / min.

[0096] Table 1

[0097]

[0098]

[0099] As can be seen from the results in Table 1, compared with Comparative Examples 1-2, the wet content of UHMWPE fiber filaments using the method and apparatus provided by the present invention is reduced by more than 30%, the unevenness of UHMWPE fiber yarn is reduced by more than 35%, the number of breaks per 100 meters is reduced or there are no breaks, and the mechanical properties of breaking strength, breaking modulus, strength variation rate CV, and elongation variation rate CV are more superior.

[0100] A comparison of the data from Examples 1-5 and Example 6 shows that setting the air supply temperature of the three sections of the air supply duct in the inner central duct within the preferred range of this invention can further improve the breaking strength and breaking modulus of UHMWPE fibers, reduce the strength variation rate (CV), elongation variation rate (CV), and yarn unevenness of UHMWPE fibers, and reduce the number of broken ends per 100 meters of UHMWPE fibers.

[0101] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing UHMWPE fibers by dry spinning, characterized in that, The method includes: spinning UHMWPE gel to obtain several filament bundles, feeding the filament bundles into an outer ring-shaped channel for stretching, setting several air outlets in the inner ring central air duct of the channel, and setting slits on the wall of the inner ring central air duct. During the stretching process, air from the air outlet is blown through the slit into the channel to supply air to the filament bundle. The stretched filament bundle is then subjected to bundling, stretching, shaping and winding processes to obtain UHMWPE fiber filaments. The fiber filaments are then subjected to post-spinning processes to obtain UHMWPE fibers. Along the fiber stretching direction, a first air outlet, a second air outlet, and a third air outlet are sequentially arranged in the inner ring central air duct. Three air outlets with different temperatures are sequentially installed in the inner central air duct.

2. The method according to claim 1, wherein, The extrusion rate of the gel after spinning is 2-10 m / min.

3. The method according to claim 1, wherein, The extrusion rate of the gel after spinning is 3-6 m / min.

4. The method according to claim 1 or 2, wherein, The air supply temperature of the first air outlet is 10-160℃.

5. The method according to claim 4, wherein, The air supply temperature of the first air outlet is 90-130℃.

6. The method according to claim 1 or 2, wherein, The air supply temperature of the second air outlet is 10-160℃.

7. The method according to claim 6, wherein, The air supply temperature of the second air outlet is 50-90℃.

8. The method according to claim 1 or 2, wherein, The air supply temperature of the third air outlet is 10-160℃.

9. The method according to claim 8, wherein, The air supply temperature of the third air outlet is 10-50℃.

10. The method according to claim 1 or 2, wherein, The air supply pressure of the first air outlet, the second air outlet, and the third air outlet is independently 10-400 kPaG.

11. The method according to claim 10, wherein, The air supply pressure of the first air outlet, the second air outlet, and the third air outlet is 100-200 kPaG each independently.

12. An apparatus for implementing the method for preparing UHMWPE fibers by dry spinning according to any one of claims 1-11, characterized in that, The device includes a channel, and a spinneret is provided at the upper part of the channel for spinning UHMWPE gel to obtain several filament bundles; The channel includes an outer annular channel and an inner central air duct. The inner central air duct has several slits on its wall to connect it to the outer annular channel. The outer annular channel is used to stretch the filament bundle. Along the direction away from the spinneret, the tunnel is sequentially provided with a first tunnel air outlet, a second tunnel air outlet, a first air supply pipe, a second air supply pipe, and a third air supply pipe; The first and second air outlets of the tunnel are arranged opposite to each other and are respectively connected to the tunnel. The first air supply pipe, the second air supply pipe, and the third air supply pipe pass through the outer ring annular channel and enter the inner ring central air supply pipe. The air supplied by the first air supply pipe, the second air supply pipe, and the third air supply pipe blows through the slit in the wall of the inner ring central air supply pipe toward the outer ring annular channel to supply air to the filament bundle, and exhausts the air through the air outlet of the first channel and the air outlet of the second channel. The lower part of the tunnel is provided with guide rollers at intervals. The central axis of the tunnel is tangent to the outer ring of the guide rollers. The guide rollers are used to bundle the stretched filaments. The openings of the first, second, and third air supply pipes are located at the central axis of the passageway and the opening direction is vertically upward.

13. The apparatus according to claim 12, wherein, The openable portion of the spinneret is a notched annular shape, and the openable portion of the spinneret is correspondingly arranged with the outer annular channel.

14. The apparatus according to claim 12 or 13, wherein, The ratio of the area of ​​the perforated portion of the spinneret to the cross-sectional area of ​​the inner central duct is 1:0.3-0.

5.

15. The apparatus according to claim 12 or 13, wherein, The bottom of the inner ring central air duct is equipped with a cap.

16. The apparatus according to claim 12 or 13, wherein, The slit is a rounded rectangle, and the ratio of the total height of the slit to the diameter of the cross-section of the inner central duct is 1:1.25-1.

3.

17. The apparatus according to claim 16, wherein, The ratio of the total height of the slit to the width of the slit is 1:0.05-0.

1.

18. The apparatus according to claim 16, wherein, The total area of ​​the slits accounts for 25-45% of the wall area of ​​the inner central duct.

Images