A melt spinning method for ultra-high molecular weight polyethylene fiber

Abstract

The present application discloses a melt spinning method for ultra-high molecular weight polyethylene fiber, comprising the following steps: step 1: mixing ultra-high molecular weight polyethylene resin with polyethylene wax and high-density polyethylene to form a composition; step 2: melting the composition at high temperature to form a melt, and performing melt spinning, and obtaining nascent fibers after being stretched by a nozzle and air-cooled; step 3: thermally stretching and thermally setting the nascent fibers to obtain the final ultra-high molecular weight polyethylene fibers. By adopting the above technical solution, high-density polyethylene and polyethylene wax can greatly improve the melt fluidity of ultra-high molecular weight polyethylene, so that the ultra-high molecular weight polyethylene resin can be melt-spun smoothly. At the same time, during the thermal stretching process, polyethylene wax can participate in the crystallization process of ultra-high molecular weight polyethylene resin and high-density polyethylene, and finally the mechanical properties of ultra-high molecular weight polyethylene fibers can be well maintained.

Description

Technical Field

[0001] The present application relates to the field of polymer technology, and more specifically, to a melt spinning method for ultra-high molecular weight polyethylene fibers. Background Art

[0002] Ultra-high molecular weight polyethylene fiber has multiple excellent properties such as light weight, high specific strength, high specific modulus, superior energy absorption, good wear resistance, corrosion resistance, and light resistance. It has been widely used in aerospace, national defense and military, security protection, marine engineering, sports equipment, power communications, medical materials, and civil ropes and nets.

[0003] Ultra-high molecular weight polyethylene fibers are usually prepared by gel spinning process. The gel spinning process is to first make a spinning solution of ultra-high molecular weight polyethylene and a suitable solvent, then form gel fibers through extrusion molding, then extract and dry the solvent in the gel fibers, and finally obtain ultra-high molecular weight polyethylene fibers through super-multiple hot drawing.

[0004] The key technology of the existing ultra-high molecular weight polyethylene fiber gel spinning process is to prepare a fully dissolved uniform solution to obtain the spinnability of the resin. However, due to the ultra-high molecular weight of the resin, the viscosity is very high when all the resin raw materials are completely dissolved, and the conditions for preparing a uniform solution are harsh, so it is difficult to obtain a high-concentration uniform solution. The solvent needs to be removed by extraction and drying methods, and the preparation process is long and the cost is high. Therefore, it is particularly important to develop melt spinning technology for ultra-high molecular weight polyethylene fibers.

[0005] "Excellent performance, difficult processing" is the characteristic of ultra-high molecular weight polyethylene. Ultra-high molecular weight polyethylene is a rubber-like high-viscosity elastic body in the melt state, with a melt viscosity of up to 10 8 Pa·s, the melt flow index is almost zero, so the critical shear rate of ultra-high molecular weight polyethylene is very low, it is easy to produce defects such as melt fracture, and it is difficult to form ultra-high molecular weight polyethylene fibers using conventional polymer melt spinning methods. Technicians in ultra-high molecular weight polyethylene fibers and related fields have been exploring a low-cost processing method for ultra-high molecular weight polyethylene fibers suitable for industrial production, which has become a technical problem that people in related fields have been eager to solve. Summary of the invention

[0006] In order to further effectively improve the processability and mechanical properties of ultra-high molecular weight polyethylene fibers, the present application provides a melt spinning method for ultra-high molecular weight polyethylene fibers.

[0007] The present application provides a melt spinning method for ultra-high molecular weight polyethylene fibers, comprising the following steps:

[0008] Step 1: mixing ultra-high molecular weight polyethylene resin, linear polyethylene wax and high-density polyethylene to form a composition;

[0009] Step 2: Melting the composition at high temperature to form a melt, and performing melt spinning, and then stretching through a nozzle and air cooling to obtain a nascent fiber;

[0010] Step 3: The spun fibers are further subjected to heat stretching and heat setting to obtain the final ultra-high molecular weight polyethylene fibers.

[0011] By adopting the above technical solution, high-density polyethylene and a weight-average molecular weight of 2.0×10 3 ~5.0×10 3 g / mol of linear polyethylene wax can greatly improve the melt fluidity of ultra-high molecular weight polyethylene, so that ultra-high molecular weight polyethylene resin can be melt-spun smoothly. At the same time, during the hot stretching process, linear polyethylene wax can participate in the crystallization process of ultra-high molecular weight polyethylene and high-density polyethylene, thereby reducing or even eliminating the destructive effect of linear polyethylene wax as a low molecular weight substance on the mechanical properties of ultra-high molecular weight polyethylene fibers, and ultimately maintaining the mechanical properties of ultra-high molecular weight polyethylene fibers. High-density polyethylene can not only improve the melt fluidity of ultra-high molecular weight polyethylene, but also eliminate the weak phase separation caused by the large molecular weight gap between ultra-high molecular weight polyethylene and polyethylene wax, thereby improving the mechanical properties of ultra-high molecular weight polyethylene fibers.

[0012] Moreover, compared with the traditional process, the present application also omits the step of using solvent to extract linear polyethylene wax, which not only reduces the use of solvents and reduces costs, but also reduces pollution to the environment.

[0013] Preferably, the composition of step 1 contains 60-90 wt% of ultra-high molecular weight polyethylene resin, 4-16 wt% of polyethylene wax, and 6-24 wt% of high-density polyethylene.

[0014] Preferably, the content of ultra high molecular weight polyethylene resin in the composition is 70 to 85 wt %.

[0015] By adopting the above technical solution, too low UHMWPE resin content will affect the mechanical properties of the final UHMWPE fiber. However, too high UHMWPE resin content will affect the preparation stability and production efficiency of the UHMWPE fiber.

[0016] Preferably, the weight average molecular weight of the high density polyethylene is 8.0×10 4 ~30.0×10 4 g / mol, branching degree is 0~1 / 10 3 .

[0017] Preferably, the composition in step 2 is melted at high temperature in a twin-screw extruder and spun through a spinning assembly, and the feeding section temperature of the twin-screw extruder is 90-140°C, the compression section temperature is 160-250°C, the homogenization section temperature is 160-250°C, the spinning assembly temperature is 160-250°C, and the rotation speed of the twin-screw extruder is 20-300r / min.

[0018] Preferably, the temperatures of the compression section, homogenization section and spinning assembly of the twin-screw extruder are all 170-200°C.

[0019] By adopting the above technical solution, within the temperature range of 160-250°C, especially within the range of 170-200°C, not only can the folded chain lamellae of the ultra-high molecular weight polyethylene resin be fully melted, but also some straight chain crystals can be retained. Thus, not only the fluidity of the ultra-high molecular weight polyethylene resin can be ensured, but also the retained straight chain crystals have very high mechanical properties, and can also act as nucleating agents to induce linear polyethylene wax and high-density polyethylene to crystallize on its surface during the stretching process, so that the ultra-high molecular weight polyethylene fiber can maintain excellent mechanical properties.

[0020] Preferably, in step 2, the raw silk is stretched 1.5 to 5 times through the nozzle.

[0021] Preferably, the raw silk is stretched 2.4 to 4.2 times through the nozzle.

[0022] By adopting the above technical solution, the nozzle stretching multiple is small, which cannot play the role of arranging the straight chain crystals retained in the melting process along the fiber axis. The nozzle stretching multiple is large, which affects the stability of the nozzle stretching.

[0023] Preferably, the temperature of the heat stretching in step 3 is 80 to 135° C., and the total multiple of the heat stretching is 6 to 30 times.

[0024] By adopting the above technical solution, the formation efficiency of straight chain crystals is low when the hot stretching temperature is low, and the degree of crystallization of linear polyethylene wax and high-density polyethylene in ultra-high molecular weight polyethylene is insufficient when the hot stretching temperature is high, and the quality instability such as doubling may also occur during the hot stretching preparation process of the fiber. The total stretching multiple can improve the mechanical properties of the fiber while taking into account the processing efficiency to a greater extent.

[0025] In summary, this application has the following beneficial effects:

[0026] 1. The present invention adopts a specific ultra-high molecular weight polyethylene, linear polyethylene wax and high-density polyethylene composition for melt spinning, so that the linear polyethylene wax and high-density polyethylene greatly improve the fluidity of the ultra-high molecular weight polyethylene during the extrusion spinning process, and fully participate in the crystallization of the ultra-high molecular weight polyethylene during the hot stretching process, thereby preparing high-performance ultra-high molecular weight polyethylene fibers, while also eliminating the use of solvents and reducing pollution to the environment;

[0027] 2. The temperature of the compression section, homogenization section and spinning assembly of the twin-screw extruder is controlled within the temperature range of 170-200°C, which can not only fully melt the folded chain lamellae of the ultra-high molecular weight polyethylene resin, but also retain the straight chain crystals. This not only ensures the fluidity of the ultra-high molecular weight polyethylene, but also improves the mechanical properties of the ultra-high molecular weight polyethylene fiber;

[0028] 3. After being stretched 2.4 to 4.2 times by the nozzle, it can not only make the ultra-high molecular weight polyethylene straight chain crystals retained in the melting process arranged along the fiber axis, but also ensure the stability of stretching;

[0029] 4. The temperature of heat stretching is controlled at 80-135°C, which not only increases the efficiency of forming straight chain crystals in ultra-high molecular weight polyethylene fibers, but also allows more linear polyethylene wax and high-density polyethylene to participate in the crystallization of ultra-high molecular weight polyethylene. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a two-dimensional wide-angle X-ray diffraction pattern of the ultra-high molecular weight polyethylene fiber in Example 1 of the present application;

[0031] Figure 2 It is a two-dimensional wide-angle X-ray diffraction pattern of the ultra-high molecular weight polyethylene fiber in Comparative Example 8 of the present application. DETAILED DESCRIPTION

[0032] The present application is further described in detail below in conjunction with the accompanying drawings, embodiments and comparative examples.

[0033] Example 1

[0034] A melt spinning method for ultra-high molecular weight polyethylene fiber, characterized in that it comprises the following steps:

[0035] Step 1: The viscosity average molecular weight is 4.12×10 6 g / mol ultra-high molecular weight polyethylene resin and a weight average molecular weight of 3.51×10 3 g / mol linear polyethylene wax, with a weight average molecular weight of 19.21×10 4 g / mol and a branching degree of 2 / 10 4 The high-density polyethylene is uniformly mixed to form a composition;

[0036] Step 2: adding the composition to a twin-screw extruder for high-temperature melting to obtain a high-temperature melt, and passing the high-temperature melt through a metering pump and a spinneret for melt spinning, and stretching the high-temperature melt by 3.2 times through a nozzle, and cooling the fiber to room temperature at 20° C. in air to obtain a nascent fiber;

[0037] Step 3: The nascent fiber is heat-stretched at 110° C. to a total multiple of 18 times, and then heat-set at 130° C. to obtain the final ultra-high molecular weight polyethylene fiber.

[0038] Among them, the content of ultra-high molecular weight polyethylene resin in the composition is 75wt%, the content of linear polyethylene wax is 10wt%, and the content of high-density polyethylene is 15wt%; the feeding section temperature of the twin-screw extruder is 115°C, the compression section temperature is 185°C, the homogenization section temperature is 185°C, the spinning component temperature is 185°C, and the speed of the twin-screw extruder is 160r / min.

[0039] Example 2

[0040] A melt spinning method for ultra-high molecular weight polyethylene fiber, characterized in that it comprises the following steps:

[0041] Step 1: The viscosity average molecular weight is 4.12×10 6 g / mol ultra-high molecular weight polyethylene resin and a weight average molecular weight of 2.0×10 3 g / mol linear polyethylene wax, weight average molecular weight of 8.0×10 4 g / mol and a branching degree of 2 / 10 4 The high-density polyethylene is uniformly mixed to form a composition;

[0042] Step 2: adding the composition to a twin-screw extruder for high-temperature melting to obtain a high-temperature melt, and passing the high-temperature melt through a metering pump and a spinneret for melt spinning, and stretching the high-temperature melt by 1.5 times through a nozzle, and cooling the fiber to room temperature at 20° C. in air to obtain a nascent fiber;

[0043] Step 3: The nascent fiber is heat-stretched at 80°C to a total multiple of 6 times, and then heat-set at 130°C to obtain the final ultra-high molecular weight polyethylene fiber.

[0044] Among them, the content of ultra-high molecular weight polyethylene resin in the composition is 60wt%, the content of polyethylene wax is 16wt%, and the content of high-density polyethylene is 24wt%; the feeding section temperature of the twin-screw extruder is 90°C, the compression section temperature is 160°C, the homogenization section temperature is 160°C, the spinning component temperature is 160°C, and the speed of the twin-screw extruder is 20r / min.

[0045] Example 3

[0046] A melt spinning method for ultra-high molecular weight polyethylene fiber, characterized in that it comprises the following steps:

[0047] Step 1: The viscosity average molecular weight is 4.12×10 6 g / mol ultra-high molecular weight polyethylene resin and a weight average molecular weight of 5.0×10 3 g / mol linear polyethylene wax, with a weight average molecular weight of 30.0×10 4 g / mol and a branching degree of 2 / 10 4 The high-density polyethylene is uniformly mixed to form a composition;

[0048] Step 2: adding the composition to a twin-screw extruder for high-temperature melting to obtain a high-temperature melt, and passing the high-temperature melt through a metering pump and a spinneret for melt spinning, and stretching the high-temperature melt through a nozzle by 5 times, and cooling the fiber to room temperature at 20° C. with air to obtain a nascent fiber;

[0049] Step 3: The nascent fiber is heat-stretched at 135° C. to a total multiple of 30 times, and then heat-set at 140° C. to obtain the final ultra-high molecular weight polyethylene fiber.

[0050] Among them, the content of ultra-high molecular weight polyethylene resin in the composition is 90wt%, the content of polyethylene wax is 4wt%, and the content of high-density polyethylene is 6wt%; the feeding section temperature of the twin-screw extruder is 140°C, the compression section temperature is 250°C, the homogenization section temperature is 250°C, the spinning component temperature is 250°C, and the speed of the twin-screw extruder is 300r / min.

[0051] Comparative Example 1:

[0052] The difference between this comparative example and Example 1 is that the weight average molecular weight is 19.21×10 4 g / mol and a branching degree of 2 / 10 4 High-density polyethylene replaces linear polyethylene wax.

[0053] Comparative Example 2:

[0054] The difference between this comparative example and Example 2 is that the weight average molecular weight is 8.0×10 4 g / mol and a branching degree of 2 / 10 4 High-density polyethylene replaces linear polyethylene wax.

[0055] Comparative Example 3:

[0056] The difference between this comparative example and Example 3 is that the weight average molecular weight is 30.0×10 4 g / mol and a branching degree of 2 / 10 4 High-density polyethylene replaces linear polyethylene wax.

[0057] Comparative Example 4:

[0058] The difference between this comparative example and Example 1 is that the weight average molecular weight is 3.51×10 3 g / mol of linear polyethylene wax to replace high-density polyethylene.

[0059] Comparative Example 5:

[0060] The difference between this comparative example and Example 2 is that the weight average molecular weight is 2.0×10 3 g / mol of linear polyethylene wax to replace high-density polyethylene.

[0061] Comparative Example 6:

[0062] The difference between this comparative example and Example 3 is that the weight average molecular weight is 5.0×10 3 g / mol of linear polyethylene wax to replace high-density polyethylene.

[0063] The tensile mechanical properties, thermal properties and crystallization properties of the ultra-high molecular weight polyethylene fibers of Examples 1 to 3 and Comparative Examples 1 to 6 were tested, and the specific testing methods are as follows.

[0064] 1. Thermal performance test

[0065] The ultra-high molecular weight polyethylene fiber was cut into pieces, 5 to 10 mg was weighed and placed in a standard aluminum crucible. The fiber was protected by a dry nitrogen flow and the thermal properties of the ultra-high molecular weight polyethylene fiber were tested using a differential scanning calorimeter (DSC). The fiber was heated from 25 °C to 200 °C at a heating rate of 10 °C / min and scanned. The thermal properties curve of the fiber was recorded.

[0066] 2. Crystallinity and orientation test

[0067] The crystallinity and orientation of the ultra-high molecular weight polyethylene fibers were tested by wide angle X-ray diffraction (WAXD) with an X-ray wavelength of 0.124 nm. The two-dimensional WAXD results were collected by a Pilatus 900K detector with a resolution of 172 × 172 μm. 2 , the distance from the detector to the sample is 210 mm. The WAXD data obtained by processing with FIT2D software. The two-dimensional WAXD image is integrated in one dimension to obtain the intensity distribution curve in the 2θ direction. Then the curve is peak-fitted, the ratio of amorphous area to crystalline area is calculated, and then the crystallinity is calculated. The calculation formula is as follows: Xc=Ac / (Ac+Aa), where Ac and Aa represent the area under the crystalline peak and amorphous peak of the I(2θ)~2θ curve, respectively.

[0068] The Hermans method is used to determine the crystal orientation of ultra-thin molecular weight polyethylene fibers. The fiber stretching direction is taken as the reference direction, and the crystal plane is set as hkl. The orientation parameter can be expressed as:

[0069]

[0070] in, is the azimuth, is the scattering intensity along the azimuth angle. f It can be calculated by the following formula:

[0071]

[0072] when f =-0.5, the normal direction of the crystal plane is perpendicular to the reference direction; when f =1, the normal direction of the crystal plane is parallel to the reference direction; when f = 0, the normal of the crystal plane is freely oriented.

[0073] 3. Tensile mechanical properties test:

[0074] The tensile mechanical properties of ultra-high molecular weight polyethylene fibers were tested at room temperature using a universal mechanical testing machine. The fibers were stretched at a speed of 50 mm / min to characterize their mechanical properties. At least five samples of each fiber were used to obtain the average value and standard deviation.

[0075] According to the above detection method, the test results of Examples 1 to 3 and Comparative Examples 1 to 3 were obtained, as shown in Table 1 below.

[0076] Table 1

[0077]

[0078] Conclusion 1:

[0079] By comparing the test results of Examples 1 to 3 with Comparative Examples 1 to 6, it can be seen that the high-density polyethylene and polyethylene wax are mixed with the ultra-high molecular weight polyethylene resin, which can greatly improve the fluidity of the ultra-high molecular weight polyethylene melt resin, so that melt spinning can be smoothly performed. At the same time, it is also beneficial to improve the mechanical properties of the ultra-high molecular weight polyethylene fiber.

[0080] In addition, the polyethylene wax in the required molecular weight range added is solid polyethylene wax, which does not need to be removed like liquid polyethylene wax.

[0081] High-density polyethylene can also eliminate the weak phase separation caused by the large molecular weight difference between ultra-high molecular weight polyethylene and polyethylene wax, and improve the mechanical properties of ultra-high molecular weight polyethylene fibers.

[0082] Example 4

[0083] The only difference between this embodiment and embodiment 1 is that the content of ultra-high molecular weight polyethylene resin in the composition is 70 wt %, the content of linear polyethylene wax is 13 wt %, and the content of high-density polyethylene is 17 wt %.

[0084] Example 5

[0085] The only difference between this embodiment and embodiment 1 is that the content of ultra-high molecular weight polyethylene resin in the composition is 80 wt %, the content of linear polyethylene wax is 8 wt %, and the content of high-density polyethylene is 12 wt %.

[0086] Example 6

[0087] The only difference between this embodiment and embodiment 1 is that the content of ultra-high molecular weight polyethylene resin in the composition is 60 wt %, the content of linear polyethylene wax is 16 wt %, and the content of high-density polyethylene is 24 wt %.

[0088] Example 7

[0089] The only difference between this embodiment and embodiment 1 is that the content of ultra-high molecular weight polyethylene resin in the composition is 90 wt %, the content of linear polyethylene wax is 4 wt %, and the content of high-density polyethylene is 6 wt %.

[0090] The ultra-high molecular weight fibers of Examples 4 to 7 were tested according to the testing method in Table 1 above, and the test results of the ultra-high molecular weight polyethylene fibers were obtained, as shown in Table 2 below.

[0091] Table 2

[0092]

[0093] Conclusion 2:

[0094] By comparing the test results of Example 1, Example 4 to Example 7, it can be seen that too low an ultra-high molecular weight polyethylene resin content will affect the mechanical properties of the final ultra-high molecular weight polyethylene fiber. However, too high an ultra-high molecular weight polyethylene resin content will affect the preparation stability and production efficiency of the ultra-high molecular weight polyethylene fiber. For this reason, the ultra-high molecular weight polyethylene resin content is preferably 70 to 85 wt%.

[0095] Comparative Example 7

[0096] The only difference between this comparative example and Example 1 is that the linear polyethylene wax is replaced by a branched polyethylene wax, and the branching degree of the branched polyethylene wax is 70 / 1000C.

[0097] The ultra-high molecular weight polyethylene fiber of Comparative Example 7 was tested according to the testing method in Table 1 above, and the test results are shown in Table 3 below.

[0098] Table 3

[0099]

[0100] Conclusion 3:

[0101] By comparing the test results of Example 1 and Comparative Example 7, it can be seen that the use of straight-chain polyethylene wax is more conducive to improving the mechanical properties of the final ultra-high molecular weight polyethylene fiber.

[0102] Example 8

[0103] The only difference between this embodiment and embodiment 1 is that the temperatures of the compression section, homogenization section and spinning assembly of the twin-screw extruder are all 170°C.

[0104] Example 9

[0105] The only difference between this embodiment and embodiment 1 is that the temperatures of the compression section, homogenization section and spinning assembly of the twin-screw extruder are all 200°C.

[0106] Example 10

[0107] The only difference between this embodiment and embodiment 1 is that the temperatures of the compression section, homogenization section and spinning assembly of the twin-screw extruder are all 160°C.

[0108] Embodiment 11

[0109] The only difference between this embodiment and embodiment 1 is that the temperatures of the compression section, homogenization section and spinning assembly of the twin-screw extruder are all 250°C.

[0110] Comparative Example 8

[0111] The only difference between this comparative example and Example 1 is that the temperatures of the compression section, homogenization section and spinning assembly of the twin-screw extruder are all 270°C.

[0112] Comparative Example 9

[0113] The only difference between this comparative example and Example 1 is that the temperatures of the compression section, homogenization section and spinning assembly of the twin-screw extruder are all 150°C.

[0114] The ultra-high molecular weight polyethylene fibers of Examples 8 to 11 and Comparative Examples 8 and 9 were tested according to the testing method in Table 1. The specific test results are shown in Table 4 below.

[0115] Table 4

[0116]

[0117] Conclusion 4:

[0118] from Figure 1 and Figure 2 By comparison, the two diffraction arcs from the inside to the outside correspond to the (110) and (200) crystal planes of the polyethylene orthorhombic crystal, and the diffraction arc angles of the (110) crystal plane are recorded as ∠1 and ∠2, respectively. Figure 2 , Figure 1 The diffraction arc of the wide-angle X-ray diffraction pattern is narrower (∠1 is smaller) and more concentrated in the 180° direction, indicating that during the stretching process, the crystals are arranged more orderly along the stretching direction and have a higher degree of orientation. Therefore, the ultra-high molecular weight polyethylene fiber of Example 1 is better oriented along the stretching direction, which is beneficial to improving the mechanical properties. In addition, combined with the comparison of the test results of Example 1, Example 8 to Example 11, and Comparative Example 8 and Comparative Example 9, when the compression section, homogenization section and spinning assembly of the twin-screw extruder are controlled within the temperature range of 160 to 250°C, especially in the temperature range of 170-200°C for high-temperature melting, it is not only more convenient for melt spinning of ultra-high molecular weight polyethylene, but also beneficial to improving the mechanical properties of the final ultra-high molecular weight polyethylene fiber.

[0119] Example 12

[0120] The only difference between this embodiment and embodiment 1 is that the raw silk is stretched 1.5 times through the nozzle.

[0121] Embodiment 13

[0122] The only difference between this embodiment and embodiment 1 is that the raw silk is stretched 5 times through the nozzle.

[0123] Embodiment 14

[0124] The only difference between this embodiment and embodiment 1 is that the raw silk is stretched 2.4 times through the nozzle.

[0125] Embodiment 15

[0126] The only difference between this embodiment and embodiment 1 is that the raw silk is stretched 4.2 times through the nozzle.

[0127] Comparative Example 10

[0128] The difference between this comparative example and Example 1 is that the raw silk is stretched 1.2 times through the nozzle.

[0129] Comparative Example 11

[0130] The only difference between this comparative example and Example 1 is that the raw silk is stretched 5.3 times through the nozzle.

[0131] The ultra-high molecular weight polyethylene fibers of Examples 12 to 15 and Comparative Examples 10 to 11 were tested according to the testing method in Table 1. The specific test results are shown in Table 5 below.

[0132] Table 5

[0133]

[0134] Conclusion 5:

[0135] By comparing the test results of Example 1, Example 12 to Example 15 and Comparative Example 10 and Comparative Example 11, it can be seen that when the precursor is stretched 1.5 to 5 times, especially 2.4 to 4.2 times, through the nozzle, not only can the preparation stability of the final ultra-high molecular weight polyethylene fiber be guaranteed, but also the mechanical properties of the ultra-high molecular weight polyethylene fiber can be improved.

[0136] Example 16

[0137] The only difference between this embodiment and embodiment 1 is that the temperature of the heat stretching is 80°C.

[0138] Embodiment 17

[0139] The only difference between this embodiment and embodiment 1 is that the temperature of the heat stretching is 135°C.

[0140] Comparative Example 12

[0141] The only difference between this comparative example and Example 1 is that the temperature of the heat stretching is 70°C.

[0142] Comparative Example 13

[0143] The only difference between this comparative example and Example 1 is that the temperature of the heat stretching is 145°C.

[0144] The ultra-high molecular weight polyethylene fibers of Examples 16 to 17 and Comparative Examples 12 to 13 were tested according to the testing method in Table 1. The specific test results are shown in Table 6 below.

[0145] Table 6

[0146]

[0147] Conclusion 6:

[0148] By comparing the test results of Example 1, Example 16 and Example 17 and Comparative Example 12 and Comparative Example 13, it can be seen that when the original hot stretching temperature is 80-145°C, it is beneficial to improve the mechanical properties of the ultra-high molecular weight polyethylene fiber.

[0149] Embodiment 18

[0150] The only difference between this embodiment and embodiment 1 is that the total multiple of heat stretching is 6 times.

[0151] Embodiment 19

[0152] The only difference between this embodiment and embodiment 1 is that the total thermal stretching multiple is 30 times.

[0153] Comparative Example 14

[0154] The only difference between this comparative example and Example 1 is that the total thermal stretching multiple is 4 times.

[0155] Comparative Example 15

[0156] The only difference between this comparative example and Example 1 is that the total thermal stretching multiple is 33 times.

[0157] The ultra-high molecular weight polyethylene fibers of Examples 18 to 19 and Comparative Examples 14 to 15 were tested according to the testing method in Table 1. The specific test results are shown in Table 7 below.

[0158] Table 7

[0159]

[0160] Conclusion 7:

[0161] By comparing the test results of Example 1, Example 18 and Example 19 and Comparative Example 14 and Comparative Example 15, it can be seen that when the stretching multiple is 6 to 30 times, not only can the mechanical properties of the fiber be improved, but also the processing efficiency can be taken into account to a greater extent.

[0162] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A melt spinning method for ultra-high molecular weight polyethylene fibers, characterized in that: The following steps are included: Step 1: 70-85 wt% of ultra-high molecular weight polyethylene resin, 4-16 wt% of linear polyethylene wax, and 6-24 wt% of high-density polyethylene are mixed to form a composition; Step 2: adding the composition to a twin-screw extruder to melt at high temperature to form a melt, and spinning the melt through a spinning assembly, stretching it by 1.5 to 5 times through a nozzle, and air cooling to obtain a nascent fiber; Step 3: The spun fibers are further subjected to heat stretching and heat setting to obtain the final ultra-high molecular weight polyethylene fibers; Among them, the weight average molecular weight of linear polyethylene wax is 2.0×10 3 ~5.0×10 3 g / mol, the feeding section temperature of the twin-screw extruder is 90-140°C, the compression section temperature is 160-250°C, the homogenization section temperature is 160-250°C, the spinning assembly temperature is 160-250°C, the speed of the twin-screw extruder is 20-300r / min, the hot stretching temperature in step 3 is 80-135°C, and the total multiple of hot stretching is 6-30 times.

2. The melt spinning method of an ultra-high molecular weight polyethylene fiber according to claim 1, characterized in that: The weight average molecular weight of the high density polyethylene is 8.0×10 4 ~30.0×10 4 g / mol, branching degree is 0~1 / 10 3 .

3. The melt spinning method of an ultra-high molecular weight polyethylene fiber according to claim 1, characterized in that: The temperatures of the compression section, homogenization section and spinning assembly of the twin-screw extruder are all 170-200°C.

4. The melt spinning method of an ultra-high molecular weight polyethylene fiber according to claim 1, characterized in that: The nozzle is stretched 2.4 to 4.2 times.

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