A device and method for preparing fine denier high-strength UHMWPE fiber

Abstract

An apparatus and method for preparing fine denier high-strength UHMWPE fibers are disclosed. The method involves adding low-entanglement UHMWPE resin and a good solvent in a stirred, expanding vessel and heating the mixture to obtain a spinning solution. The spinning solution is then passed through a twin-screw extruder to form a high-viscoelastic gel solution, which is extruded through a distributed spinneret and enters a vertical spinning box to form gel filaments. These gel filaments first pass through a cooling section within the vertical spinning box to form gel filaments. They then pass through a steam azeotropic solvent removal section to form gel filaments with a certain level of humidity. Finally, they pass through a constant-temperature dehumidification section and are drawn at a set draw ratio within the spinning box to obtain dry filaments. The dry filaments are further drawn at a set draw ratio by a post-spinning device to obtain fine denier high-strength UHMWPE fibers. The good solvent recovery rate in the preparation process of this invention is over 98%; the finished fine denier high-strength UHMWPE fiber has a fineness of 0.1-0.7 dtex, a strength of 31-45 cN / dtex, and a modulus of 1200-1700 cN / dtex.

Description

Technical Field

[0001] This invention relates to the field of polymer materials, especially fiber materials, and particularly to the field of dry spinning for preparing ultra-high molecular weight polyethylene fibers. Specifically, it relates to a highly efficient and energy-saving spinning process, equipment, and fibers for preparing fine denier, high-strength ultra-high molecular weight polyethylene fibers. Background Technology

[0002] In existing technologies for the preparation and production of ultra-high molecular weight polyethylene (UHMWPE) fibers, dry spinning refers to the process of preparing UHMWPE spinning dope by mixing and swelling UHMWPE resin with highly volatile solvents, such as decahydronaphthalene. After the spinning dope is extruded from the spinneret, decahydronaphthalene is vaporized and released in a high-temperature inert gas atmosphere to obtain dry gel filaments, which are then stretched at high ratios to obtain high-strength, high-modulus polyethylene fibers.

[0003] Currently, the dry spinning technology for high-performance polyethylene fibers in China has been industrialized. Its core technology involves the extrusion of the raw material liquid through a spinneret. The volatile solvent decahydronaphthalene in the raw material liquid is vaporized in high-temperature nitrogen gas and exchanges heat with the side-blowing air and tunnel air below the spinneret. The side-blowing air and tunnel air carry it into the recovery system. The gas in the recovery system needs to go through a series of high-energy-consuming and high-power-consumption equipment and processes such as compression, condensation, adsorption-desorption, and membrane separation to remove and recover the solvent, thereby enabling the raw material liquid to form gel filaments. Summary of the Invention

[0004] The purpose of this invention is to address the problems of high energy consumption in the traditional high-temperature inert gas flow for purging volatile solvents during the above-mentioned spinning process. At the same time, the high temperature during the process can easily cause incompletely untangled UHMWPE gel fibers to stick together or dissolve in reverse in the solvent decahydronaphthalene that is not removed in time, resulting in problems such as fuzziness, breakage, or uneven fineness in the prepared fibers. Therefore, this invention proposes an equipment and method for preparing fine denier high-strength UHMWPE fibers.

[0005] The main technical solution of this invention is as follows: An apparatus for preparing fine denier high-strength UHMWPE fibers, comprising swelling, extrusion, and post-spinning equipment, characterized in that a distributed spinneret assembly and a vertical spinning box are provided after the extrusion equipment; the distributed spinneret assembly includes multiple spinnerets with different orifice diameters, arranged in a matrix or single-row configuration; the vertical spinning box includes, from top to bottom, a spinning cooling section, a steam azeotropic solvent removal section, and a constant temperature dehumidification section; the steam azeotropic solvent removal section includes a vertical steam inner pipe, the wall of which is provided with steam jet sprayers corresponding to the fiber bundle channels.

[0006] Furthermore, the middle of the cooling section consists of a single-row or matrix-arranged filament channel, while the periphery consists of a channel for flowing freezing medium.

[0007] Furthermore, the middle of the steam azeotropic solvent removal section is a single-row arrangement of filament channels, with a steam jet sprayer placed on one side of the filament channels.

[0008] Furthermore, the middle of the steam azeotropic solvent removal section is a matrix-arranged filament channel, with steam jet sprayers placed on one side and both sides of the filament channel.

[0009] Furthermore, the vertical steam inner pipe of the steam azeotropic solvent removal section is connected to the high-pressure steam pipeline network through a steam transition tank; the steam outlet of the steam azeotropic solvent removal section is equipped with a steam regulating valve and a steam condensation solvent recovery pipeline.

[0010] Furthermore, the steam condensation solvent recovery pipeline is coiled around the periphery of the constant temperature dehumidification section fiber bundle channel.

[0011] This invention also provides a method for preparing fine denier high-strength UHMWPE fibers, using the above-mentioned equipment, and comprising the following steps:

[0012] Low-entanglement UHMWPE resin and a good solvent are added to a stirred swelling vessel and heated to obtain a spinning solution.

[0013] The spinning solution is formed into a highly viscoelastic gel solution by a twin-screw extruder, and after being extruded by a distributed spinneret, it enters a vertical spinning box to form gel filaments;

[0014] In a vertical spinning box, the gel filaments first pass through a cooling section to form gel filaments; then through a steam azeotropic solvent removal section to form gel filaments with a certain humidity; finally, through a constant temperature and dehumidification section, and after being drawn at a set draw ratio within the box, dry filaments are obtained.

[0015] Dry raw yarn is further drawn by the drawn ratio set by the spinning equipment to obtain fine denier high-strength UHMWPE fiber.

[0016] Further, in step 1), the UHMWPE resin has a viscosity-average molecular weight of 4 million to 6.5 million and an entanglement degree of 0.1 to 0.6; the good solvent is selected from decahydronaphthalene, tetrahydronaphthalene, and xylene; the ratio of UHMWPE resin to good solvent is (5:94) to (12:88); after heating to 80°C, the temperature is gradually increased to 95°C at a rate of 5°C per hour and then stabilized for one hour.

[0017] Furthermore, the cooling section has a temperature control range of -30℃ to 10℃, preferably -20℃ to 0℃, and more preferably -15℃ to 5℃.

[0018] Furthermore, in the steam azeotropic solvent removal section, the steam entering the spinning box has a steam dryness of 90, a steam pressure of 50KPa-300KPa, preferably 80KPa-200KPa, more preferably 100KPa-160KPa, and a temperature of 80℃-130℃, preferably 90℃-120℃, more preferably 102℃-110℃.

[0019] Furthermore, in the steam azeotropic solvent removal section, the steam jet spray nozzle has a gas velocity of 1m / s-5m / s.

[0020] Furthermore, the residence time of the filament bundle in the cooling and dehumidification section is 10-120s, preferably 20-100s, more preferably 30-90s; the moisture content of the filament bundle is 60%-98%, preferably 70%-95%, more preferably 80%-90%; the residence time of the filament bundle in the steam azeotropic solvent removal section is 10-300s, preferably 30-200s, more preferably 45-135s; the moisture content of the filament bundle is 1%-30%, preferably 2%-20%, more preferably 4%-10%; the residence time of the filament bundle in the constant temperature dehumidification section is 30-400s, preferably 50-240s, more preferably 60-180s; and the moisture content of the filament bundle is less than 2%.

[0021] Furthermore, the heat source for the constant temperature dehumidification section is provided by the high-pressure steam from the steam condensation solvent recovery pipeline and pipeline network of the steam azeotropic solvent removal section, and the temperature is controlled at 120±5℃ by a steam regulating valve.

[0022] Furthermore, the draw ratio in step 3) is 5-40 times, preferably 10-30 times, and more preferably 18-26 times.

[0023] The good solvent recovery rate in the preparation process of this invention is over 98%; the finished fine denier high-strength UHMWPE fiber has a fineness of 0.1-0.7 dtex, a strength of 31-45 cN / dtex, and a modulus of 1200-1700 cN / dtex. Beneficial effects

[0024] By employing the steam azeotropic method implemented in this invention to remove solvent from gel-coated filaments during the spinning process, the volatile solvent azeosulates with the steam under the action of flowing steam at different temperatures and pressures within the spinning box, thereby rapidly removing the water / solvent mixture from the fiber surface. A steam condensation solvent recovery pipe is installed at the steam outlet on the side of the hot box for solvent recovery. Simultaneously, the latent heat of the steam condensate can be used for insulation of the lower section of the hot box. Therefore, the goal of efficient solvent recovery can be achieved under low energy consumption conditions, which not only greatly reduces the operating cost of the device but also significantly reduces the equipment setup. Attached Figure Description

[0025] Figure 1This is a schematic diagram of the spinneret assembly and spinning box in the equipment for preparing fine denier high-strength UHMWPE fibers according to an embodiment of the present invention.

[0026] Figure 2 This is a top view of the spinneret arrangement in the embodiment.

[0027] Figure 3 This is a top view of the upper part of the spinning box in the embodiment.

[0028] In the diagram, 1-spinneret assembly; 2-cooling section; 3-steam azeotropic solvent removal section; 4-steam condensation solvent recovery pipeline; 5-constant temperature dehumidification section; 6-solvent collection tank; 7-bundling; 8-steam regulating valve; 9-steam transfer tank; 11-top view of single-row spinneret assembly arrangement; 12-top view of matrix arrangement of spinneret assembly; 21-top view of single-row arrangement of filament channels in cooling section; 22-top view of matrix arrangement of filament channels in cooling section. Implementation

[0029] The present invention will now be described in detail with reference to embodiments and accompanying drawings. Example

[0030] An apparatus for preparing fine denier high-strength UHMWPE fibers mainly includes swelling, extrusion, and post-spinning equipment. Its innovation lies in the addition of a distributed spinneret assembly 1 and a vertical spinning box after the extrusion equipment (see attached diagram). Figure 1-3 The distributed spinneret assembly 1 includes multiple spinnerets with different orifice diameters, arranged in a matrix or single-row configuration (see attached diagram). Figure 2 The vertical spinning box includes, from top to bottom, a spinning cooling section 2, a steam azeotropic solvent removal section 3, and a constant temperature dehumidification section 5; the steam azeotropic solvent removal section 3 includes a vertical steam inner pipe, and the wall of the vertical steam inner pipe is equipped with a steam spray nozzle corresponding to the yarn channel.

[0031] In this embodiment, the middle of the cooling section 2 is a single-row or matrix-arranged filament channel, and the periphery is a flow cooling medium channel (see attached diagram). Figure 3 ).

[0032] In the embodiment, the middle of the steam azeotropic solvent removal section 3 is a filament channel arranged in a single row or matrix. When arranged in a single row, the steam jet sprayer is placed on one side of the filament channel. When arranged in a matrix, the steam jet sprayer is placed on one side and the front and rear sides of the filament channel.

[0033] In this embodiment, the vertical steam inner pipe of the steam azeotropic solvent removal section 3 is connected to the high-pressure steam pipeline network through the steam transition tank 9; the steam outlet of the steam azeotropic solvent removal section 3 is equipped with a steam regulating valve 8 and a steam condensation solvent recovery pipe 4, which is coiled around the periphery of the fiber bundle channel of the constant temperature dehumidification section 5.

[0034] The following embodiments use the above-mentioned equipment to prepare fine denier high-strength UHMWPE fibers. During the preparation process, steam is provided by a high-pressure steam pipeline network and sprayed out through the vertical steam inner pipe wall of the steam azeotropic solvent removal section 3. The heat source of the constant temperature dehumidification section 5 is provided by the high-pressure steam of the steam condensation solvent recovery pipeline 4 and the pipeline network. Example 1

[0035] 1.25 kg of ultra-high molecular weight polyethylene resin with a viscosity-average molecular weight of 6 million and an entanglement degree of 0.368 was added to a swelling vessel containing 20 L of solvent decahydronaphthalene with stirring. The mixture was heated to 80°C and then gradually increased to 95°C at a rate of 5°C per hour, stabilizing for one hour to complete the preparation of the spinning solution. The spinning solution was then fed from a self-circulating homogenizing vessel into a twin-screw extruder for further swelling, dissolution, shearing, defoaming, and backmixing to form a high viscoelastic gel solution. After extrusion through multiple matrix-type or single-row arranged spinnerets 1, the solution first entered and passed through the cooling section 2 of a vertical spinning box. The cooling medium temperature was set to -10℃. After the fiber bundle remained in this section for 60 seconds, it entered the steam azeotropic solvent removal section 3 of the spinning box. The fiber bundle underwent solvent removal in a steam atmosphere at 106℃ and 135KPa. After remaining in this section for 90 seconds, the fiber bundle entered the constant temperature dehumidification section 5 of the spinning box. It remained in the box at a set temperature of 120±5℃ for 120 seconds to further reduce the moisture content of the fiber. After being drawn 22 times within the box, the bundle was collected and dropped into the bobbin to obtain dry raw fibers. The condensate generated by the azeotropic process entered the solvent collection tank 6 through the steam condensation solvent recovery pipe 4 for recovery. After the device was running stably, the moisture content of the fiber bundles at the end of the upper cooling section, the middle steam azeotropic solvent removal section, and the lower constant temperature dehumidification section of the spinning box was sampled and analyzed. The test results were 86.64%, 7.21%, and 1.33%, respectively, and the solvent recovery rate of the spinning process was 98.46%. The dry raw yarn from the bobbin is subjected to a three-stage drawing process with a total ratio of 9.5 times in the post-spinning equipment to prepare the fine denier high-strength ultra-high molecular weight polyethylene fiber obtained in this invention. Its performance test results are as follows: single filament fineness 0.19 dtex, breaking strength 44.12 cN / dtex, and modulus 1608 cN / dtex. Example 2

[0036] 1.25 kg of ultra-high molecular weight polyethylene resin with a viscosity-average molecular weight of 5 million and an entanglement degree of 0.315 was added to a swelling vessel containing 20 L of solvent decahydronaphthalene with stirring. The mixture was heated to 80°C and then gradually increased to 95°C at a rate of 5°C per hour, stabilizing for one hour to complete the preparation of the spinning solution. The spinning solution was then fed from a self-circulating homogenizing vessel into a twin-screw extruder for further swelling, dissolution, shearing, defoaming, and backmixing to form a high viscoelastic gel solution. After extrusion through multiple matrix-type or single-row arranged spinnerets 1, the solution first entered and passed through the cooling section 2 of a vertical spinning box. The cooling medium temperature was set to -5℃. After the fiber bundle remained in this section for 90 seconds, it entered the steam azeotropic solvent removal section 3 of the spinning box. The fiber bundle underwent solvent removal in a steam atmosphere at 102℃ and 116KPa. After remaining in this section for 135 seconds, the fiber bundle entered the constant temperature dehumidification section 5 of the spinning box. It remained in the box at a set temperature of 120±5℃ for 180 seconds to further reduce the moisture content of the fiber. After being drawn 18 times within the box, the fiber bundle was collected and dropped into the drum to obtain dry raw yarn. The condensate generated by the azeotropic process entered the solvent collection tank 6 through the steam condensation solvent recovery pipe 4 for recovery. After the device was running stably, the moisture content of the fiber bundle at the end of the upper cooling section, the middle steam azeotropic solvent removal section, and the lower constant temperature dehumidification section of the spinning box was sampled and analyzed. The test results were 81.57%, 4.54%, and 1.00%, respectively, and the solvent recovery rate of the spinning process was 98.78%. The dry raw yarn from the bobbin is subjected to a three-stage drawing process with a total ratio of 12 in the post-spinning equipment to prepare the fine denier high-strength ultra-high molecular weight polyethylene fiber obtained in this invention. The performance test results are as follows: single filament fineness 0.27 dtex, breaking strength 42.54 cN / dtex, and modulus 1543 cN / dtex. Example 3

[0037] 1.15 kg of ultra-high molecular weight polyethylene resin with a viscosity-average molecular weight of 6.5 million and an entanglement degree of 0.414 was added to a swelling vessel containing 20 L of solvent decahydronaphthalene with stirring. The mixture was heated to 80°C and then gradually increased to 95°C at a rate of 5°C per hour, stabilizing for one hour to complete the preparation of the spinning solution. The spinning solution was then fed from a self-circulating homogenizing vessel into a twin-screw extruder for further swelling, dissolution, shearing, defoaming, and backmixing to form a high viscoelastic gel solution. After extrusion through multiple matrix-type or single-row spinnerets 1, the solution first entered and passed through the cooling section 2 of a vertical spinning box. The internal cooling medium temperature is set to -15℃. After the fiber bundle stays in this section for 30 seconds, it enters the steam azeotropic solvent removal section 3 of the spinning box. The fiber bundle undergoes solvent removal in a steam atmosphere at 110℃ and 150KPa. After staying in this section for 45 seconds, the fiber bundle enters the constant temperature dehumidification section 5 of the spinning box. It stays in the box at a set temperature of 120±5℃ for 60 seconds to further reduce the moisture content of the fiber. After being drawn 26 times within the box, the bundle is collected and dropped into the bobbin to obtain dry raw fibers. The condensate generated by the azeotropic process enters the solvent collection tank 6 through the steam condensation solvent recovery pipe 4 for recovery. After the device is running stably, the moisture content of the fiber bundles at the end of the upper cooling section, the middle steam azeotropic solvent removal section, and the lower constant temperature dehumidification section of the spinning box is sampled and analyzed. The test results are 89.25%, 9.18%, and 1.57%, respectively, and the solvent recovery rate of the spinning process is 98.78%. The dry raw yarn from the bobbin is subjected to a three-stage drawing process with a total ratio of 7.5 times in the post-spinning equipment to prepare the fine denier high-strength ultra-high molecular weight polyethylene fiber obtained in this invention. Its performance test results are as follows: single filament fineness 0.21 dtex, breaking strength 43.18 cN / dtex, and modulus 1578 cN / dtex. Example 4

[0038] 1.05 kg of ultra-high molecular weight polyethylene resin with a viscosity-average molecular weight of 5 million and an entanglement degree of 0.356 was added to a swelling vessel containing 20 L of solvent decahydronaphthalene with stirring. The mixture was heated to 80°C and then gradually increased to 95°C at a rate of 5°C per hour, stabilizing for one hour to complete the preparation of the spinning solution. The spinning solution was then fed from a self-circulating homogenizing vessel into a twin-screw extruder for further swelling, dissolution, shearing, defoaming, and backmixing to form a high viscoelastic gel solution. After extrusion through multiple matrix-type or single-row spinnerets, the solution first entered and passed through the cooling section 2 of a vertical spinning box. The cooling medium temperature is set to 0℃. After the fiber bundle stays in this section for 120s, it enters the steam azeotropic solvent removal section 3 of the spinning box. The fiber bundle undergoes solvent removal in a steam atmosphere at 100℃ and 100KPa. After staying in this section for 180s, the fiber bundle enters the constant temperature dehumidification section 5 of the spinning box. It stays in the box at a set temperature of 120±5℃ for 240s to further reduce the moisture content of the fiber. After being drawn 10 times within the box, the bundle is collected 7 and dropped into the bobbin to obtain dry raw fibers. The condensate generated by the azeotropic process enters the solvent collection tank 6 through the steam condensation solvent recovery pipe 4 for recovery. After the device is running stably, the moisture content of the fiber bundles at the end of the upper cooling section, the middle steam azeotropic solvent removal section, and the lower constant temperature dehumidification section of the spinning box is sampled and analyzed. The test results are 75.41%, 3.37%, and 0.75%, respectively, and the solvent recovery rate of the spinning process is 99.01%. The dry raw yarn from the bobbin is processed through a three-stage drawing process with a total ratio of 8 times in the post-spinning equipment to prepare the fine denier high-strength ultra-high molecular weight polyethylene fiber obtained in this invention. The performance test results are as follows: single filament fineness 0.56 dtex, breaking strength 32.45 cN / dtex, and modulus 1238 cN / dtex. Example 5

[0039] 1.35 kg of ultra-high molecular weight polyethylene resin with a viscosity-average molecular weight of 4.5 million and an entanglement degree of 0.298 was added to a swelling vessel containing 20 L of solvent decahydronaphthalene with stirring. The mixture was heated to 80°C and then gradually increased to 95°C at a rate of 5°C per hour, stabilizing for one hour to complete the preparation of the spinning solution. The spinning solution was then fed from a self-circulating homogenizing vessel into a twin-screw extruder for further swelling, dissolution, shearing, defoaming, and backmixing to form a high viscoelastic gel solution. After extrusion through multiple matrix-type or single-row spinnerets, the solution first entered and passed through the cooling section of a vertical spinning box. The cooling medium temperature was set to -20℃. After the fiber bundle remained in this section for 20 seconds, it entered the steam azeotropic solvent removal section 3 of the spinning box. The fiber bundle underwent solvent removal in a steam atmosphere at 115℃ and 181KPa. After remaining in this section for 30 seconds, the fiber bundle entered the constant temperature dehumidification section 5 of the spinning box. It remained in the box at a set temperature of 120±5℃ for 40 seconds to further reduce the moisture content of the fiber. After being drawn 28 times within the box, the bundle was collected and dropped into the bobbin to obtain dry raw fibers. The condensate generated by the azeotropic process entered the solvent collection tank 6 through the steam condensation solvent recovery pipe 4 for recovery. After the device was running stably, the moisture content of the fiber bundles at the end of the upper cooling section, the middle steam azeotropic solvent removal section, and the lower constant temperature dehumidification section of the spinning box was sampled and analyzed. The test results were 95.11%, 14.45%, and 1.84%, respectively, and the solvent recovery rate of the spinning process was 98.07%. The dry raw yarn from the bobbin is subjected to a three-stage drawing process with a total ratio of 5.4 times in the post-spinning equipment to prepare the fine denier high-strength ultra-high molecular weight polyethylene fiber obtained in this invention. Its performance test results are as follows: single filament fineness 0.37 dtex, breaking strength 36.28 cN / dtex, and modulus 1475 cN / dtex. Example 6

[0040] 1.15 kg of ultra-high molecular weight polyethylene resin with a viscosity-average molecular weight of 5.5 million and an entanglement degree of 0.364 was added to a swelling vessel containing 20 L of solvent decahydronaphthalene with stirring. The mixture was heated to 80°C and then gradually increased to 95°C at a rate of 5°C per hour, stabilizing for one hour to complete the preparation of the spinning solution. The spinning solution was then fed from a self-circulating homogenizing vessel into a twin-screw extruder for further swelling, dissolution, shearing, defoaming, and backmixing to form a high viscoelastic gel solution. After extrusion through multiple matrix-type or single-row spinnerets 1, the solution first entered and passed through the cooling section 2 of a vertical spinning box. The internal cooling medium temperature is set to -15℃. After the fiber bundle stays in this section for 30 seconds, it enters the steam azeotropic solvent removal section 3 of the spinning box. The fiber bundle undergoes solvent removal in a steam atmosphere at 112℃ and 163KPa. After staying in this section for 45 seconds, the fiber bundle enters the constant temperature dehumidification section 5 of the spinning box. It stays in the box at a set temperature of 120±5℃ for 60 seconds to further reduce the moisture content of the fiber. After being drawn 24 times within the box, the bundle is collected and dropped into the bobbin to obtain dry raw fibers. The condensate generated by the azeotropic process enters the solvent collection tank 6 through the steam condensation solvent recovery pipe 4 for recovery. After the device is running stably, the moisture content of the fiber bundles at the end of the upper cooling section, the middle steam azeotropic solvent removal section, and the lower constant temperature dehumidification section of the spinning box is sampled and analyzed. The test results are 93.28%, 12.78%, and 1.70%, respectively, and the solvent recovery rate of the spinning process is 98.18%. The dry raw yarn from the bobbin is subjected to a three-stage drawing process with a total ratio of 6.1 in the post-spinning equipment to prepare the fine denier high-strength ultra-high molecular weight polyethylene fiber obtained in this invention. Its performance test results are as follows: single filament fineness 0.61 dtex, breaking strength 35.56 cN / dtex, and modulus 1279 cN / dtex. Example 7

[0041] 1.05 kg of ultra-high molecular weight polyethylene resin with a viscosity-average molecular weight of 6 million and an entanglement degree of 0.378 was added to a swelling vessel containing 20 L of solvent decahydronaphthalene with stirring. The mixture was heated to 80°C and then gradually increased to 95°C at a rate of 5°C per hour, stabilizing for one hour to complete the preparation of the spinning solution. The spinning solution was then fed from a self-circulating homogenizing vessel into a twin-screw extruder for further swelling, dissolution, shearing, defoaming, and backmixing to form a high viscoelastic gel solution. After extrusion through multiple matrix-type or single-row spinnerets 1, the solution first entered and passed through the cooling section 2 of a vertical spinning box. The cooling medium temperature was set to -10℃. After the fiber bundle remained in this section for 60 seconds, it entered the steam azeotropic solvent removal section 3 of the spinning box. The fiber bundle underwent solvent removal in a steam atmosphere at 118℃ and 200KPa. After remaining in this section for 90 seconds, the fiber bundle entered the constant temperature dehumidification section 5 of the spinning box. It remained in the box at a set temperature of 120±5℃ for 120 seconds to further reduce the moisture content of the fiber. After being drawn 24 times within the box, the bundle was collected and dropped into the bobbin to obtain dry raw fibers. The condensate generated by the azeotropic process entered the solvent collection tank 6 through the steam condensation solvent recovery pipe 4 for recovery. After the device was running stably, the moisture content of the fiber bundles at the end of the upper cooling section, the middle steam azeotropic solvent removal section, and the lower constant temperature dehumidification section of the spinning box was sampled and analyzed. The test results were 90.16%, 10.67%, and 1.40%, respectively, and the solvent recovery rate of the spinning process was 98.45%. The dry raw yarn from the bobbin is subjected to a three-stage drawing process with a total ratio of 6.5 times in the post-spinning equipment to prepare the fine denier high-strength ultra-high molecular weight polyethylene fiber obtained in this invention. Its performance test results are as follows: single filament fineness 0.49 dtex, breaking strength 36.78 cN / dtex, and modulus 1429 cN / dtex. Example 8

[0042] 1.45 kg of ultra-high molecular weight polyethylene resin with a viscosity-average molecular weight of 4 million and an entanglement degree of 0.351 was added to a swelling vessel containing 20 L of solvent decahydronaphthalene with stirring. The mixture was heated to 80°C and then gradually increased to 95°C at a rate of 5°C per hour, stabilizing for one hour to complete the preparation of the spinning solution. The spinning solution was then fed from a self-circulating homogenizing vessel into a twin-screw extruder for further swelling, dissolution, shearing, defoaming, and backmixing to form a high viscoelastic gel solution. After extrusion through multiple matrix-type or single-row arranged spinnerets 1, the solution first entered and passed through the cooling section 2 of a vertical spinning box. The cooling medium temperature was set to -5℃. After the fiber bundle remained in this section for 90 seconds, it entered the steam azeotropic solvent removal section 3 of the spinning box. The fiber bundle underwent solvent removal in a steam atmosphere at 100℃ and 100KPa. After remaining in this section for 135 seconds, the fiber bundle entered the constant temperature dehumidification section 5 of the spinning box. It remained in the box at a set temperature of 120±5℃ for 180 seconds to further reduce the moisture content of the fiber. After being drawn 16 times within the box, the bundle was collected and dropped into the bobbin to obtain dry raw fibers. The condensate generated by the azeotropic process entered the solvent collection tank 6 through the steam condensation solvent recovery pipe 4 for recovery. After the device was running stably, the moisture content of the fiber bundles at the end of the upper cooling section, the middle steam azeotropic solvent removal section, and the lower constant temperature dehumidification section of the spinning box was sampled and analyzed. The test results were 82.25%, 5.51%, and 1.48%, respectively, and the solvent recovery rate of the spinning process was 98.20%. The dry raw yarn from the bobbin is subjected to a three-stage drawing process with a total ratio of 7.5 times in the post-spinning equipment to prepare the fine denier high-strength ultra-high molecular weight polyethylene fiber obtained in this invention. Its performance test results are as follows: single filament fineness 0.38 dtex, breaking strength 38.18 cN / dtex, and modulus 1276 cN / dtex. Example 9

[0043] 1.45 kg of ultra-high molecular weight polyethylene resin with a viscosity-average molecular weight of 4.5 million and an entanglement degree of 0.376 was added to a swelling vessel containing 20 L of solvent decahydronaphthalene with stirring. The mixture was heated to 80°C and then gradually increased to 95°C at a rate of 5°C per hour, stabilizing for one hour to complete the preparation of the spinning solution. The spinning solution was then fed from a self-circulating homogenizing vessel into a twin-screw extruder for further swelling, dissolution, shearing, defoaming, and backmixing to form a high viscoelastic gel solution. After extrusion through multiple matrix-type or single-row arranged spinnerets 1, the solution first entered and passed through the cooling section 2 of a vertical spinning box. The cooling medium temperature was set to -20℃. After the fiber bundle remained in this section for 20 seconds, it entered the steam azeotropic solvent removal section 3 of the spinning box. The fiber bundle underwent solvent removal in a steam atmosphere at 125℃ and 249KPa. After remaining in this section for 30 seconds, the fiber bundle entered the constant temperature dehumidification section 5 of the spinning box. It remained in the box at a set temperature of 120±5℃ for 40 seconds to further reduce the moisture content of the fiber. After being drawn 24 times within the box, the bundle was collected and dropped into the bobbin to obtain dry raw fibers. The condensate generated by the azeotropic process entered the solvent collection tank 6 through the steam condensation solvent recovery pipe 4 for recovery. After the device was running stably, the moisture content of the fiber bundles at the end of the upper cooling section, the middle steam azeotropic solvent removal section, and the lower constant temperature dehumidification section of the spinning box was sampled and analyzed. The test results were 96.74%, 15.68%, and 1.67%, respectively, and the solvent recovery rate of the spinning process was 98.27%. The dry raw yarn from the bobbin is subjected to a three-stage drawing process with a total ratio of 5.5 times in the post-spinning equipment to prepare the fine denier high-strength ultra-high molecular weight polyethylene fiber obtained in this invention. Its performance test results are as follows: single filament fineness 0.29 dtex, breaking strength 40.16 cN / dtex, and modulus 1315 cN / dtex.

[0044] By employing the steam azeotropic method implemented in this invention to remove solvent from gel-coated filaments during the spinning process, the volatile solvent azeosulates with the steam under the action of flowing steam at different temperatures and pressures within the spinning box, thereby rapidly removing the water / solvent mixture from the fiber surface. A steam recovery pipe is installed at the steam outlet on the side of the hot box for solvent recovery. Simultaneously, the latent heat of the steam condensate can be used for insulation of the lower section of the hot box. Therefore, the goal of efficient solvent recovery can be achieved under low energy consumption conditions, which not only greatly reduces the operating cost of the device but also significantly reduces the equipment setup.

Claims

1. An apparatus for preparing fine denier high-strength UHMWPE fibers, comprising swelling, extrusion, and post-spinning equipment, characterized in that... The extrusion equipment is followed by a distributed spinneret assembly and a vertical spinning box; the distributed spinneret assembly includes multiple spinnerets with different orifice diameters, arranged in a matrix or single row; the vertical spinning box includes a spinning cooling section, a steam azeotropic solvent removal section, and a constant temperature dehumidification section from top to bottom; the steam azeotropic solvent removal section includes a vertical steam inner pipe, and the wall of the vertical steam inner pipe is equipped with steam jet sprayers corresponding to the yarn bundle channel.

2. The device according to claim 1, characterized in that... The cooling section has a single-row or matrix-arranged filament channel in the middle and a flowing freezing medium channel on the periphery.

3. The device according to claim 1, characterized in that... The middle of the steam azeotropic solvent removal section is a single-row arrangement of filament channels, with a steam jet sprayer placed on one side of the filament channels.

4. The device according to claim 1, characterized in that... The middle of the steam azeotropic solvent removal section is a matrix-arranged filament channel, with steam jet sprayers placed on one side and both sides of the filament channel.

5. The device according to claim 1, characterized in that... The vertical steam inner pipe of the steam azeotropic solvent removal section is connected to the high-pressure steam pipeline network through a steam transition tank; the steam outlet of the steam azeotropic solvent removal section is equipped with a steam regulating valve and a steam condensation solvent recovery pipeline.

6. The device according to claim 5, characterized in that... The steam condensation solvent recovery pipeline is coiled around the periphery of the constant temperature dehumidification section's fiber bundle channel.

7. A method for preparing fine denier high-strength UHMWPE fibers, characterized in that... Using the device according to any one of claims 1-6, the steps include: Low entanglement UHMWPE resin and a good solvent are added to a stirred swelling vessel and heated to obtain a spinning solution. The spinning solution is formed into a highly viscoelastic gel solution by a twin-screw extruder, and after being extruded by a distributed spinneret, it enters a vertical spinning box to form gel filaments; In a vertical spinning box, the gel filaments first pass through a cooling section to form gel filaments; then through a steam azeotropic solvent removal section to form gel filaments with a certain humidity; finally, through a constant temperature and dehumidification section, and after being drawn at a set draw ratio within the box, dry filaments are obtained. Dry raw yarn is further drawn by the drawn ratio set by the spinning equipment to obtain fine denier high-strength UHMWPE fiber.

8. The method according to claim 7, characterized in that In step 1), the UHMWPE resin has a viscosity-average molecular weight of 4 million to 6.5 million and an entanglement degree of 0.1 to 0.6; the good solvent is selected from decahydronaphthalene, tetrahydronaphthalene, and xylene; the ratio of UHMWPE resin to good solvent is (5:94) to (12:88); after heating to 80°C, the temperature is gradually increased to 95°C at a rate of 5°C per hour and then stabilized for one hour.

9. The method according to claim 7, characterized in that... The cooling section has a temperature control range of -30℃ to 10℃.

10. The method according to claim 7, characterized in that... In the steam azeotropic solvent removal section, the steam entering the spinning box has a dryness of 90%, a pressure of 50KPa-300KPa, and a temperature of 80℃-130℃.

11. The method according to claim 7, characterized in that... In the steam azeotropic solvent removal section, the steam jet spray nozzle has an air velocity of 1m / s-5m / s.

12. The method according to claim 7, characterized in that... The residence time of the filament bundle in the cooling and dehumidification section is 10-120s; the moisture content of the filament bundle is 60%-98%; the residence time of the filament bundle in the steam azeotropic solvent removal section is 10-300s; the moisture content of the filament bundle is 1%-30%; the residence time of the filament bundle in the constant temperature dehumidification section is 30-400s; the moisture content of the filament bundle is less than 2%.

13. The method according to claim 7, characterized in that... The heat source for the constant temperature dehumidification section is provided by the high-pressure steam from the steam condensation solvent recovery pipeline and pipeline network of the steam azeotropic solvent removal section, and the temperature is controlled at 120±5℃ by the steam regulating valve.

14. The method according to claim 7, characterized in that... The draw ratio in step 3) is 5-40 times.

15. The method according to any one of claims 7-14, characterized in that... The good solvent recovery rate during the preparation process is over 98%; the finished fine denier high-strength UHMWPE fiber has a fineness of 0.1-0.7 dtex, a strength of 31-45 cN / dtex, and a modulus of 1200-1700 cN / dtex.

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