UHMWPE (Ultra High Molecular Weight Polyethylene) dry spinning process and fiber preparation method

Abstract

According to the novel UHMWPE dry spinning process and the fiber preparation method, on the basis of an existing dry spinning technology, the dry spinning technological process is greatly shortened, the operation cost of the device is reduced, and the production efficiency of the device is improved on the basis of guaranteeing the fiber quality. The device mainly comprises a preparation unit of primary gel wet filaments and a subsequent multi-stage high-power drafting unit. The primary gel wet strand preparation unit is characterized in that a gel melt of UHWMPE resin is extruded and bundled at a high speed and high pressure through a spinneret plate with inverted conical spinneret orifices, then enters a condensation bath which is located below the spinneret plate and is provided with a bundling roller and a godet, and enters a multi-stage high-power drafting unit through a multi-roller drafting machine after going out of the condensation bath; the multi-stage high-power drafting unit comprises at least three steam azeotropic drafting hot boxes with different temperatures and pressures for multi-stage drafting; and the bundling roller, the godet and the condensation bath can move up and down.

Description

Technical Field

[0001] The invention relates to the technical field of polymer materials, especially dry spinning to prepare ultra-high molecular weight polyethylene fibers, and specifically to process parameters and equipment in the fiber spinning process and ultra-high molecular weight polyethylene fibers. Background Art

[0002] Ultra-high molecular weight polyethylene (UHMWPE) fiber is also called high-strength and high-modulus polyethylene fiber. Currently, the processing and preparation of this fiber has been industrialized. The more mature process routes are dry spinning route and wet spinning route, depending on the raw material solvents used.

[0003] The wet spinning route is represented by Dyneema® of Honeywell in the United States. Its process characteristics are that low-volatile solvents (mineral oil, white oil, etc.) are used to prepare ultra-high molecular weight polyethylene gel precursors. After the gel precursors are extruded from the spinneret, they enter a water bath (or a mixed bath of water and ethylene glycol, etc.) to solidify to obtain wet gel precursors containing low-volatile solvents. The wet gel precursors are extracted with a highly volatile extractant and a continuous extraction device in multiple stages to replace the low-volatile solvent to obtain gel precursors (a mixture of the extractant, solvent and water is collected and sent to a distillation device for separation and recovery). The extractant in the gel precursor is dried in multiple stages and fully vaporized to obtain dry gel precursors. After high-multiple drawing, high-strength and high-modulus polyethylene fibers are obtained. Domestically, the fiber preparation technology developed by Donghua University has been industrialized in more than a dozen companies such as Beijing Tongyi, Hunan Zhongtai, Zhejiang Dacheng, Shandong Aidi, and Beijing Weiya.

[0004] The dry spinning route is represented internationally by Dyneema® of DSM of the Netherlands, which uses highly volatile decahydronaphthalene solvent to prepare ultra-high molecular weight polyethylene spinning solution. After the spinning solution is extruded from the spinneret, the decahydronaphthalene is vaporized and escaped to obtain dry gel precursor, which is then stretched to obtain high-strength and high-modulus polyethylene fibers. This process route was developed relatively late in China. After 2008, Yizheng Chemical Fiber (using the first-generation product technology of this project jointly cooperated with the applicant unit) built and put into production the first 300t / a high-performance polyethylene fiber dry spinning industrial device, with a current production capacity of 3,300 tons. It is also the only company in China that produces ultra-high molecular weight polyethylene fibers by dry spinning.

[0005] In the dry spinning expansion test and the specific implementation of the industrial device, the preparation of low-entanglement primary gel wet filaments, the amount of solvent evaporation on the surface of the filaments during the high-multiple drawing of the filament bundle, and the speed of spinning have a great impact on the performance indicators of the fiber. In the technology provided by Chinese patent CN110079881B, the fiber is not subjected to high-multiple drawing in a constant temperature freezer or a closed hot box, and the frozen gelatin raw yarn still contains spinning solvent of not less than 30% of the raw yarn weight, which is not conducive to the subsequent drawing process, and the residual solvent amount in the fiber also limits its scope of use. Summary of the invention

[0006] The purpose of the present invention is to overcome the above-mentioned shortcomings and to provide a new UHMWPE dry spinning process and fiber preparation method, which greatly shortens the dry spinning process flow and reduces the operating cost of the device on the basis of the existing dry spinning technology, and improves the production efficiency of the device while ensuring the fiber quality.

[0007] The main technical scheme of the present invention is: a UHMWPE dry spinning process, characterized in that it includes a preparation unit for primary gel wet filaments and a subsequent multi-stage high-multiple drawing unit; the primary gel wet filament preparation unit includes: the gel melt of the UHWMPE resin is extruded and bundled at high speed and high pressure through a spinneret provided with an inverted cone-shaped spinneret hole, and then enters a condensation bath provided with a bundling roller and a guide roller located below the spinneret, and after exiting the condensation bath, enters the multi-stage high-multiple drawing unit through a multi-roller drawing machine; the multi-stage high-multiple drawing unit includes: at least three steam azeotropic drawing hot boxes with different temperatures and pressures for multi-stage drawing; the bundling roller, the guide roller and the condensation bath can all move up and down.

[0008] Furthermore, after the prepared raw material liquid is swollen and homogenized, a gel melt is formed through a twin-screw extruder. The gel melt after passing through a booster pump and a metering pump enters a primary gel wet filament preparation unit. The gel melt pressure out of the booster pump is 2.0-6.5 MPa, preferably 3.0-5.5 MPa, and more preferably 3.5-4.5 MPa.

[0009] Furthermore, the inverted cone-shaped spinneret is a circular hole, comprising an upper and lower section, the upper section is inverted cone-shaped, and the lower section is straight-cylindrical; the D / d ratio of the inverted cone-shaped spinneret in the outer dimensions is 3:1-15:1, preferably 5:1-12:1, more preferably 6:1-8:1, and H / h is 2:1-10:1, preferably 3:1-8:1, more preferably 4:1-6:1; the (H+h) / d ratio is 15:1-40:1, preferably 18:1-35:1, more preferably 20:1-30:1, wherein D is the upper diameter, d is the lower diameter, H is the height of the upper inverted cone-shaped section, and h is the height of the lower straight-cylindrical section.

[0010] Furthermore, the extrusion rate of the primary gel wet filaments exiting the inverted cone-shaped spinneret is 5-30 m / min, preferably 10-20 m / min, and more preferably 10-15 m / min.

[0011] Furthermore, the residence time of the primary gel wet filaments exiting the inverted cone-shaped spinneret in the condensation bath is 5-50 s, preferably 10-30 s, more preferably 10-20 s.

[0012] Furthermore, the multi-roller drawing machine is a five-roller drawing machine, and its drawing ratio is 1-3 times, preferably 1-2 times, and more preferably 1-1.5 times.

[0013] Furthermore, the primary gel wet filaments are drawn in three or four stages through three or four steam azeotropic drawing hot boxes.

[0014] Furthermore, the yarn output speed of the last stage of multi-stage drawing is 150-600 m / min, preferably 200-500 m / min, and more preferably 300-400 m / min.

[0015] The present invention also provides a method for preparing UHMWPE fibers. The raw fibers prepared by the dry spinning process of the present invention are stored in a static room for 24-48 hours, and then sent to a post-spinning process for multi-stage hot drawing to prepare ultra-high molecular weight polyethylene fine denier fibers of different specifications. The finished UHMWPE fibers are obtained by winding the raw fibers on a tow winding machine.

[0016] Preferably, the residual solvent content in the finished fiber is 5-50 ppm, preferably 10-30 ppm, more preferably 10-20 ppm.

[0017] Generally, the UHMWPE dry spinning process provided by the present invention is specifically implemented as follows.

[0018] (1) UHWMPE resin with a molecular weight range of 2 million to 4 million is pre-swelled with solvent decalin in an amount not less than 10% of the total mass of the raw material, and then fed into a parallel twin-screw extruder for further swelling, dissolution and transportation to form a gel melt. The pressure of the melt after passing through a booster pump and a metering pump is maintained at 3.5-4.5 MPa, and the melt is extruded at a high speed and high pressure of 10-15 m / min through an inverted cone-shaped spinneret (11) with an aspect ratio [(H+h) / d] of 20:1. The primary gel wet filaments exiting the cone-shaped spinneret are bundled and sent to a five-roller drawing machine. The nozzle drawing ratio of the filaments in this process is 1.0-1.5 times. At the same time, during this process, the residence time of the filament bundle in the condensation bath water tank below the spinneret does not exceed 10-20 seconds. The residence time of the filament bundle can be adjusted by a bundling roller (3) and a guide roller (4) that can move up and down and are arranged in the condensation bath water tank.

[0019] (2) The newly formed gel wet filaments from the five-roll drawing machine are subjected to at least three stages of drawing in a steam azeotropic hot box, wherein the first stage drawing ratio is not higher than 10 times, the second stage drawing ratio is not higher than 30 times, and the third stage drawing ratio is not higher than 5 times. The speed of the filaments exiting the third stage azeotropic drawing hot box is 300-400 m / min.

[0020] According to the method for preparing UHMWPE fibers provided by the present invention, after the primary raw fibers are subjected to multi-stage drawing in a steam azeotropic hot box and then to a drying hot box and post-spinning drawing treatment, the residual solvent content in the finished fibers is 5-50 ppm, preferably 10-30 ppm, and more preferably 10-20 ppm.

[0021] Beneficial effects: Based on the existing dry spinning technology, the present invention greatly shortens the spinning process, reduces the operating cost of the device, and improves the production efficiency of the device on the basis of ensuring the fiber quality. The improved setting of the spinneret and the spinneret hole reduces the shearing effect of the gel fluid under high pressure, thereby reducing the molecular weight degradation caused by the mechanical action of the spinning process; the higher spinneret extrusion speed and low-ratio nozzle drafting ensure that the low entanglement state of the viscoelastic gel out of the spinneret is not destroyed by excessive drafting; the multi-stage drafting set in the steam azeotropic hot box ensures the high-ratio drafting of the fiber, thereby achieving the high-strength and high-modulus characteristics of the fiber; the original process flow is greatly shortened, the uniformity of the fineness of the UHMWPE fiber prepared by dry spinning is effectively improved, and the operating cost of the device is greatly reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a partial schematic diagram of the dry spinning process in the embodiment provided by the present invention.

[0023] Figure 2 Schematic diagram of top view of spinneret in the embodiment.

[0024] Figure 3 2 is a front cross-sectional schematic diagram of a spinneret in an embodiment.

[0025] Figure 4 Schematic diagram of the enlarged structure of the spinneret hole in the embodiment.

[0026] In the figure, 1-spinneret; 2-condensation bath; 3-bunching roller; 4-guide roller; 5-drawing machine; 11-spinneret hole. Implementation

[0027] The present invention will be described in detail below through examples and drawings. Example

[0028] (I) A UHMWPE dry spinning process reference Figure 1, mainly including the preparation unit (A) of the primary gel wet filaments and the subsequent multi-stage high-multiple drawing unit (B). The primary gel wet filament preparation unit (A) mainly includes a spinneret 1 with an inverted cone-shaped spinneret hole 11, a condensing bath 2 with a bunching roller 3 and a guide roller 4 located below the spinneret 1, and a five-roller drawing machine 5 behind the condensing bath 2; the multi-stage high-multiple drawing unit (B) mainly includes three steam azeotropic drawing hot boxes (B1, B2, B3) with different temperatures and pressures; the bunching roller 3, the guide roller 4 and the condensing bath 2 can all move up and down.

[0029] (ii) Dry spinning steps: After pre-swelling of UHWMPE resin with a viscosity-average molecular weight range of 2-4 million with solvent decalin and other additives in an amount not less than 10% of the total mass of the raw materials, the resin is fed into a parallel twin-screw extruder for further swelling, dissolution and transportation to form a gel melt. The pressure of the melt is maintained at 3.5-4.5 MPa after passing through a booster pump and a metering pump. After high-speed and high-pressure extrusion and bundling through an inverted cone spinneret with an aspect ratio [(H+h) / d] of 20:1, the melt enters a condensation bath located below the spinneret for a short stay, and enters a steam azeotropic hot box multi-stage drawing unit (B) through a five-roll drawing machine for 3-stage drawing. The filament bundles exiting the azeotropic hot box pass through a five-roll drawing machine, enter a drying hot box for drying, and are wound to obtain ultra-high molecular weight polyethylene fiber precursors.

[0030] (III) Fiber preparation process: After the raw yarn prepared above is kept in a static room for 24-48 hours, it is sent to post-spinning for multi-stage hot drawing to prepare ultra-high molecular weight polyethylene fine denier fibers of different specifications, and the finished UHMWPE fiber is obtained by winding the tow on a winding machine.

[0031] The data related to the embodiment are measured after the device has been running stably for 4-12 hours under the set process parameters. The method for measuring the fineness and mechanical properties of the finished fiber is as follows: the fineness and mechanical properties of the finished fiber are measured according to the national standard GB / T19975-2005 method. Example 1

[0032] After pre-swelling of a UHWMPE resin with a viscosity-average molecular weight ranging from 2 million to 4 million with a solvent decalin and other additives in an amount not less than 10% of the total weight of the raw materials, the resin is fed into a parallel twin-screw extruder for further swelling, dissolution and transportation to form a gel melt. The pressure of the melt is maintained at 3.5±0.1 MPa after passing through a booster pump and a metering pump. The melt is bundled in a condensation bath (2) at an extrusion speed of 12 m / min through an inverted cone spinneret (11) with an aspect ratio [(H+h) / d] of 22. The residence time is 10±1s, the nozzle drawing ratio of the gel tow is 1, and it enters the steam azeotropic hot box multi-stage drawing unit (B) through a five-roller drawing machine (5) for three-stage drawing. The drawing ratio in the azeotropic hot box (B1) is 1.1 times, the drawing ratio in the azeotropic hot box (B2) is 10 times, and the drawing ratio in the azeotropic hot box (B3) is 2.3 times. The tow exiting the azeotropic hot box (B3) passes through a five-roller drawing machine at a linear speed of 300m / min, enters a drying hot box for drying, and is wound to obtain ultra-high molecular weight polyethylene fiber precursor.

[0033] The raw yarn obtained from the dry spinning process of preparing UHMWPE of the present invention was stored in a static room for 24 hours and then sent to post-spinning, and was hot-drawn under the following conditions: the first-stage hot-drawing temperature was 143° C., and the degree of drawing was 3 times; the second-stage hot-drawing temperature was 147° C., and the drawing multiple was 5 times; the third-stage hot-drawing temperature was 148° C., and the drawing multiple was 1.1 times, to prepare ultra-high molecular weight polyethylene fine denier fiber, and the finished UHMWPE fiber was obtained by winding on the tow, and samples were taken for relevant mechanical property detection and analysis, and the results are shown in Table 1. Example 2

[0034] After pre-swelling of a UHWMPE resin with a viscosity-average molecular weight ranging from 2 million to 4 million with a solvent decalin and other additives in an amount not less than 10% of the total weight of the raw materials, the resin is fed into a parallel twin-screw extruder for further swelling, dissolution and transportation to form a gel melt. The pressure of the melt is maintained at 3.7±0.1 MPa after passing through a booster pump and a metering pump. The melt is bundled in a condensation bath (2) at an extrusion speed of 15 m / min through an inverted cone spinneret (11) with an aspect ratio [(H+h) / d] of 22. The residence time is 8±1s, the nozzle drawing ratio of the gel tow is 1.2, and it enters the steam azeotropic hot box multi-stage drawing unit (B) through a five-roller drawing machine (5) for three-stage drawing. The drawing ratio in the azeotropic hot box (B1) is 1.2 times, the drawing ratio in the azeotropic hot box (B2) is 12 times, and the drawing ratio in the azeotropic hot box (B3) is 1.7 times. The tow exiting the azeotropic hot box (B3) passes through a five-roller drawing machine at a linear speed of 300m / min, enters a drying hot box for drying, and is wound to obtain ultra-high molecular weight polyethylene fiber precursor.

[0035] The raw yarn obtained from the dry spinning process of preparing UHMWPE of the present invention was stored in a static room for 24 hours and then sent to post-spinning, and was hot-drawn under the following conditions: the first-stage hot-drawing temperature was 142° C., and the degree of drawing was 2 times; the second-stage hot-drawing temperature was 146° C., and the drawing multiple was 6 times; the third-stage hot-drawing temperature was 148° C., and the drawing multiple was 1.2 times, to prepare ultra-high molecular weight polyethylene fine denier fiber, and the finished UHMWPE fiber was obtained by winding the tow on the tow winder, and samples were taken for relevant mechanical property detection and analysis, and the results are shown in Table 1. Example 3

[0036] After pre-swelling of a UHWMPE resin with a viscosity-average molecular weight ranging from 2 million to 4 million with a solvent decalin and other additives in an amount not less than 10% of the total weight of the raw materials, the resin is fed into a parallel twin-screw extruder for further swelling, dissolution and transportation to form a gel melt. The pressure of the melt is maintained at 4.0±0.1 MPa after passing through a booster pump and a metering pump. The melt is bundled in a condensation bath (2) at an extrusion speed of 14 m / min through an inverted cone spinneret (11) with an aspect ratio [(H+h) / d] of 22. The residence time is 9±1s, the nozzle drawing ratio of the gel tow is 1.1, and it enters the steam azeotropic hot box multi-stage drawing unit (B) through a five-roller drawing machine (5) for three-stage drawing. The drawing ratio in the azeotropic hot box (B1) is 1.0 times, the drawing ratio in the azeotropic hot box (B2) is 14 times, and the drawing ratio in the azeotropic hot box (B3) is 1.8 times. The tow exiting the azeotropic hot box (B3) passes through a five-roller drawing machine at a linear speed of 350m / min, enters a drying hot box for drying, and is wound to obtain ultra-high molecular weight polyethylene fiber precursor.

[0037] The raw yarn obtained from the dry spinning process of preparing UHMWPE of the present invention was stored in a static room for 24 hours and then sent to post-spinning, and was hot-drawn under the following conditions: the first-stage hot-drawing temperature was 140° C., and the drawing multiple was 1.5 times; the second-stage hot-drawing temperature was 143° C., and the drawing multiple was 4 times; the third-stage hot-drawing temperature was 147° C., and the drawing multiple was 1.5 times, to prepare ultra-high molecular weight polyethylene fine denier fiber, and the finished UHMWPE fiber was obtained by winding the tow on the tow winder, and samples were taken for relevant mechanical property detection and analysis, and the results are shown in Table 1. Example 4

[0038] After pre-swelling of a UHWMPE resin with a viscosity-average molecular weight ranging from 2 million to 4 million with a solvent decalin and other additives in an amount not less than 10% of the total weight of the raw materials, the resin is fed into a parallel twin-screw extruder for further swelling, dissolution and transportation to form a gel melt. The melt is maintained at a pressure of 4.2±0.1 MPa after passing through a booster pump and a metering pump. The melt is bundled in a condensation bath (2) at an extrusion speed of 16 m / min through an inverted cone spinneret (11) with an aspect ratio [(H+h) / d] of 28. The residence time is 7±1s, the nozzle drawing ratio of the gel tow is 1.3, and it enters the steam azeotropic hot box multi-stage drawing unit (B) through a five-roller drawing machine (5) for three-stage drawing. The drawing ratio in the azeotropic hot box (B1) is 1.1 times, the drawing ratio in the azeotropic hot box (B2) is 12.8 times, and the drawing ratio in the azeotropic hot box (B3) is 1.5 times. The tow exiting the azeotropic hot box (B3) passes through a five-roller drawing machine at a linear speed of 340m / min, enters a drying hot box for drying, and is wound to obtain ultra-high molecular weight polyethylene fiber precursor.

[0039] The raw yarn obtained from the dry spinning process of preparing UHMWPE of the present invention was stored in a static room for 24 hours and then sent to post-spinning, and hot-drawn under the following conditions: the first-stage hot-drawing temperature was 143° C., and the degree of drawing was 2.0 times; the second-stage hot-drawing temperature was 146° C., and the drawing multiple was 5 times; the third-stage hot-drawing temperature was 148° C., and the drawing multiple was 2.0 times, to prepare ultra-high molecular weight polyethylene fine denier fiber, and the finished UHMWPE fiber was obtained by winding on the tow, and samples were taken for relevant mechanical property detection and analysis, and the results are shown in Table 1. Example 5

[0040] After pre-swelling of a UHWMPE resin with a viscosity-average molecular weight ranging from 2 million to 4 million with a solvent decalin and other additives in an amount not less than 10% of the total weight of the raw materials, the resin is fed into a parallel twin-screw extruder for further swelling, dissolution and transportation to form a gel melt. The pressure of the melt is maintained at 4.0±0.1 MPa after passing through a booster pump and a metering pump. The melt is bundled in a condensation bath (2) at an extrusion speed of 10 m / min through an inverted cone spinneret (11) with an aspect ratio [(H+h) / d] of 28. The residence time is 11±1s, the nozzle drawing ratio of the gel tow is 1, and it enters the steam azeotropic hot box multi-stage drawing unit (B) through a five-roller drawing machine (5) for three-stage drawing. The drawing ratio in the azeotropic hot box (B1) is 1.5 times, the drawing ratio in the azeotropic hot box (B2) is 15 times, and the drawing ratio in the azeotropic hot box (B3) is 1.6 times. The tow exiting the azeotropic hot box (B3) passes through a five-roller drawing machine at a linear speed of 350m / min, enters a drying hot box for drying, and is wound to obtain ultra-high molecular weight polyethylene fiber precursor.

[0041] The raw yarn obtained from the dry spinning process of preparing UHMWPE of the present invention was stored in a static room for 24 hours and then sent to post-spinning, and was hot-drawn under the following conditions: the first-stage hot-drawing temperature was 140° C., and the degree of drawing was 1.8 times; the second-stage hot-drawing temperature was 145° C., and the drawing multiple was 6 times; the third-stage hot-drawing temperature was 146° C., and the drawing multiple was 1.8 times, to prepare ultra-high molecular weight polyethylene fine denier fiber, and the finished UHMWPE fiber was obtained by winding the tow on the tow winder, and samples were taken for relevant mechanical property detection and analysis, and the results are shown in Table 1. Example 6

[0042] After pre-swelling of a UHWMPE resin with a viscosity-average molecular weight ranging from 2 million to 4 million with a solvent decalin and other additives in an amount not less than 10% of the total weight of the raw materials, the resin is fed into a parallel twin-screw extruder for further swelling, dissolution and transportation to form a gel melt. The pressure of the melt is maintained at 4.2±0.1 MPa after passing through a booster pump and a metering pump. The melt is bundled in a condensation bath (2) at an extrusion speed of 12 m / min through an inverted cone spinneret (11) with an aspect ratio [(H+h) / d] of 28. The residence time is 10±1s, the nozzle drawing ratio of the gel tow is 1.1, and it enters the steam azeotropic hot box multi-stage drawing unit (B) through a five-roller drawing machine (5) for three-stage drawing. The drawing ratio in the azeotropic hot box (B1) is 1.2 times, the drawing ratio in the azeotropic hot box (B2) is 15 times, and the drawing ratio in the azeotropic hot box (B3) is 1.5 times. The tow exiting the azeotropic hot box (B3) passes through a five-roller drawing machine at a linear speed of 320m / min, enters a drying hot box for drying, and is wound to obtain ultra-high molecular weight polyethylene fiber precursor.

[0043] The raw yarn obtained from the dry spinning process of preparing UHMWPE of the present invention was stored in a static room for 24 hours and then sent to post-spinning, and was hot-drawn under the following conditions: the first-stage hot-drawing temperature was 142° C., and the drawing multiple was 2.0 times; the second-stage hot-drawing temperature was 146° C., and the drawing multiple was 5 times; the third-stage hot-drawing temperature was 149° C., and the drawing multiple was 2.0 times, to prepare ultra-high molecular weight polyethylene fine denier fiber, and the finished UHMWPE fiber was obtained by winding on the tow, and samples were taken for relevant mechanical property detection and analysis, and the results are shown in Table 1. Example 7

[0044] After pre-swelling of a UHWMPE resin with a viscosity-average molecular weight ranging from 2 million to 4 million with a solvent decalin and other additives in an amount not less than 10% of the total weight of the raw materials, the resin is fed into a parallel twin-screw extruder for further swelling, dissolution and transportation to form a gel melt. The pressure of the melt is maintained at 4.5±0.1 MPa after passing through a booster pump and a metering pump. The melt is bundled in a condensation bath (2) at an extrusion speed of 18 m / min through an inverted cone spinneret (11) with an aspect ratio [(H+h) / d] of 28. The residence time is 7±1s, the nozzle drawing ratio of the gel tow is 1.5, and it enters the steam azeotropic hot box multi-stage drawing unit (B) through a five-roller drawing machine (5) for three-stage drawing. The drawing ratio in the azeotropic hot box (B1) is 1.1 times, the drawing ratio in the azeotropic hot box (B2) is 14 times, and the drawing ratio in the azeotropic hot box (B3) is 1.5 times. The tow exiting the azeotropic hot box (B3) passes through a five-roller drawing machine at a linear speed of 400m / min, enters a drying hot box for drying, and is wound to obtain ultra-high molecular weight polyethylene fiber precursor.

[0045] The raw yarn obtained from the dry spinning process of preparing UHMWPE of the present invention was stored in a static room for 24 hours and then sent to post-spinning, and was hot-drawn under the following conditions: the first-stage hot-drawing temperature was 144° C., and the drawing multiple was 3.0 times; the second-stage hot-drawing temperature was 147° C., and the drawing multiple was 6 times; the third-stage hot-drawing temperature was 148° C., and the drawing multiple was 1.5 times, to prepare ultra-high molecular weight polyethylene fine denier fiber, and the finished UHMWPE fiber was obtained by winding the tow on the tow winder, and samples were taken for relevant mechanical property detection and analysis, and the results are shown in Table 1.

[0046] Table 1 Example test analysis results

[0047] The adoption of this technical invention can greatly shorten the spinning process on the basis of the existing dry spinning technology, reduce the operating cost of the device, and improve the production efficiency of the device on the basis of ensuring the quality of the fiber. The improved setting of the spinneret and the spinneret hole reduces the shearing effect of the gel fluid under high pressure, thereby reducing the molecular weight degradation caused by the mechanical action of the spinning process; the higher spinneret extrusion speed and low-ratio nozzle drafting ensure that the low entanglement state of the viscoelastic gel out of the spinneret is not destroyed by excessive drafting; the multi-stage drafting set in the steam azeotropic hot box ensures the high-ratio drafting of the fiber, thereby achieving the high-strength and high-modulus characteristics of the fiber; the original process flow is greatly shortened, the uniformity of the fineness of the UHMWPE fiber prepared by dry spinning is effectively improved, and the operating cost of the device is greatly reduced.

Claims

1. A UHMWPE dry spinning process, characterized in that: It includes a preparation unit for primary gel wet filaments and a subsequent multi-stage high-multiple drawing unit; the primary gel wet filament preparation unit includes: the gel melt of UHWMPE resin is extruded and bundled at high speed and high pressure through a spinneret with inverted cone-shaped spinneret holes, and then enters a condensation bath provided with a bundling roller and a guide roller below the spinneret, and after exiting the condensation bath, enters the multi-stage high-multiple drawing unit through a multi-roller drawing machine; the multi-stage high-multiple drawing unit includes: at least three steam azeotropic drawing hot boxes with different temperatures and pressures for multi-stage drawing; the bundling roller, the guide roller and the condensation bath can all move up and down.

2. The UHMWPE dry spinning process according to claim 1, characterized in that: After the prepared raw material liquid is swollen and homogenized, a gel melt is formed through a twin-screw extruder. The gel melt after passing through a booster pump and a metering pump enters a primary gel wet filament preparation unit. The gel melt pressure out of the booster pump is 2.0-6.5 MPa, preferably 3.0-5.5 MPa, and more preferably 3.5-4.5 MPa.

3. The UHMWPE dry spinning process according to claim 1, characterized in that: The inverted cone-shaped spinneret is a circular hole, including an upper and lower section, the upper section is inverted cone-shaped, and the lower section is straight-cylindrical; the outer dimensions of the inverted cone-shaped spinneret have a D / d ratio of 3:1-15:1, preferably 5:1-12:1, more preferably 6:1-8:1, and H / h of 2:1-10:1, preferably 3:1-8:1, more preferably 4:1-6:1; the (H+h) / d ratio is 15:1-40:1, preferably 18:1-30:1, more preferably 20:1-30:1, wherein D is the upper diameter, d is the lower diameter, H is the height of the upper inverted cone-shaped section, and h is the height of the lower straight-cylindrical section.

4. The UHMWPE dry spinning process according to claim 1, characterized in that: The extrusion rate of the primary gel wet filaments exiting the inverted cone-shaped spinneret is 5-30 m / min, preferably 10-20 m / min, more preferably 10-15 m / min.

5. The UHMWPE dry spinning process according to claim 1, characterized in that: The residence time of the primary gel wet filaments exiting the inverted cone-shaped spinneret in the condensation bath is 5-50 s, preferably 10-30 s, more preferably 10-20 s.

6. The UHMWPE dry spinning process according to claim 1, characterized in that: The multi-roller drawing machine is a five-roller drawing machine, and its drawing ratio is 1-3 times, preferably 1-2 times, and more preferably 1-1.5 times.

7. The UHMWPE dry spinning process according to claim 1, characterized in that: The primary gel wet filaments are drawn in three or four stages through three or four steam azeotropic drawing heat boxes.

8. The UHMWPE dry spinning process according to claim 1 or 8, characterized in that: The yarn output speed of the last stage of multi-stage drawing is 150-600 m / min, preferably 200-500 m / min, more preferably 300-400 m / min.

9. A method for preparing UHMWPE fiber, characterized in that: The raw yarn prepared by the spinning process according to any one of claims 1 to 8 is stored in a static room for 24 to 48 hours, and then sent to a post-spinning machine for multi-stage hot drawing to prepare ultra-high molecular weight polyethylene fine denier fibers of different specifications, and the UHMWPE fiber finished product is obtained by winding the yarn bundle on a winding machine.

10. The method for preparing UHMWPE fiber according to claim 9, characterized in that: The residual solvent content in the finished fiber is 5-50 ppm, preferably 10-30 ppm, more preferably 10-20 ppm.

Images