Method for preparing wear-resistant and fatigue-resistant ultrahigh molecular weight polyethylene fiber and application thereof in ropes and cables

Abstract

The application discloses a preparation method of wear-resistant and fatigue-resistant ultrahigh molecular weight polyethylene fiber and application of the fiber in ropes and cables. Through limited swelling treatment, light stabilizer system mother liquor introduction, high shear dispersion and deoxygenation treatment, the light stabilizer is uniformly dispersed in the fiber. The obtained fiber has high strength, high wear resistance, excellent fatigue resistance, ultraviolet aging resistance and low creep performance, and is suitable for the field of high-strength ropes and cables.

Description

Technical Field

[0001] This invention relates to the technical field of ultra-high molecular weight polyethylene (UHMWPE) fibers, and in particular to a gel spinning method for preparing UHMWPE fibers and their application in high-strength ropes and cables. Background Technology

[0002] Ultra-high molecular weight polyethylene (UHMWPE) fiber, with its extremely high specific strength, low density, excellent abrasion resistance, chemical corrosion resistance, and good flexibility, has become a core material in the field of high-performance ropes and cables. In the marine engineering field, UHMWPE fiber ropes and cables are widely used in deep-sea mooring cables, tow cables, anchor ropes, and floating platform mooring systems, gradually replacing traditional steel wire ropes and aramid ropes. Its advantages lie in its extremely low creep tendency, excellent bending fatigue performance, and high strength-to-weight ratio, significantly reducing the self-weight of the ropes and cables and improving operational safety. In recent years, to further meet the needs of complex working conditions, researchers at home and abroad have conducted extensive work on fiber modification. The main technical approaches include: introducing nanoparticles (such as SiO2, carbon nanotubes), short fiber reinforcing phases (such as basalt short fibers, glass short fibers), mother liquor modification with coupling agents and antioxidants (such as the method described in CN107326462B), as well as post-spinning crosslinking, surface coating, or UV absorber addition. These modifications significantly improve the fiber's abrasion and cut resistance as well as its short-term mechanical stability, enabling its application in personal protective equipment (such as cut-resistant gloves) and some medium- and low-strength ropes. Simultaneously, by optimizing molecular weight distribution, orientation control, and low-creep formulations, the long-term stability of the ropes under static load conditions is further enhanced.

[0003] However, existing UHMWPE fiber and rope manufacturing technologies still have significant shortcomings under long-term marine service conditions. In particular, the UV-induced photo-oxidation reaction is difficult to effectively suppress, leading to strength decay, increased creep rate, and shortened bending fatigue life, which may not meet the design life requirements for deep-sea mooring and other applications. Commonly used antioxidants in existing technologies (such as hindered phenolic pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and phosphite tris(2,4-di-tert-butyl)phosphite) mainly function by capturing peroxide radicals (ROO•) and decomposing hydrogen peroxides (ROOH) during thermal oxidation. They have almost no quenching ability for the photo-oxidation process, which is excited by 290-400 nm UV radiation to generate alkyl radicals (R•) from the CH bonds of the molecular chain and initiates a chain β-fracture reaction. This reaction leads to main chain breakage, a sharp decrease in molecular weight, an increase in defects in the crystalline region, and damage to the molecular chain orientation, thereby amplifying the creep rate and bending fatigue sensitivity. Summary of the Invention

[0004] This application provides a method for preparing wear-resistant and fatigue-resistant ultra-high molecular weight polyethylene fiber, comprising the following steps: S1. Mix ultra-high molecular weight polyethylene powder with a weight average molecular weight of 3 million to 6 million with white oil, and subject it to restricted swelling treatment at 110 to 140°C to form a gel precursor system with semi-swollen segments as the main component of ultra-high molecular weight polyethylene. S2. The light-stabilized system is introduced into the gel precursor system in the form of a solvent mother liquor, and a high-shear dispersion treatment is applied at 150-175℃ to obtain a uniform and transparent spinning solution. S3. The spinning solution is subjected to controlled vacuum and inert gas synergistic deoxidation treatment under high temperature and high viscosity conditions; S4. The deoxygenated spinning solution is subjected to extrusion molding, air gap gelation, solvent extraction, multi-stage hot stretching and heat setting treatment in sequence to obtain ultra-high molecular weight polyethylene fiber.

[0005] It should be noted that in this invention, the ultra-high molecular weight polyethylene powder is subjected to restricted swelling treatment at 110–140°C, so that the polymer segments are in a predominantly semi-swollen gel precursor state, thereby establishing preliminary segment relaxation and mobility space without complete dissolution. Based on this, a light-stabilizing system is introduced in the form of a solvent mother liquor and uniformly dispersed under higher temperature and high shear conditions, allowing the light stabilizer to enter the system synchronously with the semi-swollen polyethylene segments, preventing migration or phase separation during subsequent spinning. Simultaneously, controlled vacuum and inert gas synergistic deoxygenation treatment under high temperature and high viscosity effectively reduces the impact of dissolved oxygen and trace gases on the polymer segments and light stabilizer, providing a stable spinning solution basis for subsequent extrusion, gelation, and multi-stage thermal stretching processes, thus ensuring the comprehensive performance of the obtained ultra-high molecular weight polyethylene fiber in terms of structural uniformity and long-term service stability.

[0006] A preferred technical solution for preparing wear-resistant and fatigue-resistant ultra-high molecular weight polyethylene fiber involves controlling the order of addition to initially disperse the light-stabilized system in white oil, followed by heating the resulting system at 60–120°C with continuous stirring to obtain a stabilizer solvent mother liquor with a predetermined mass concentration. The light-stabilized system comprises a triazine UV absorber and a hindered amine light stabilizer. The triazine UV absorber is 2-(4,6-diphenyl-1,3,5-triazine-2-yl)-5-hexoxy-phenol, and the hindered amine light stabilizer is bis(1-octyloxy-2,2,6,6-tetramethyl-4-piperidine) sebacate.

[0007] It should be noted that this invention controls the order in which triazine UV absorbers and hindered amine light stabilizers are introduced, allowing the two types of light stabilizers to undergo molecular-scale dissolution and initial dispersion sequentially in the white oil system. This avoids local enrichment or self-aggregation caused by differences in polarity and molecular structure. Furthermore, a stable solvent mother liquor is formed through continuous heating and stirring at 60–120°C, ensuring that the light-stabilized system can achieve synchronous and uniform dispersion in the high-viscosity polyethylene gel precursor system. Based on this, the triazine UV absorbers inhibit photoinduced reactions through selective absorption of UV radiation, while the hindered amine light stabilizers inhibit oxidative breakage of polymer chains by continuously capturing free radicals during photo-oxidation. The synergistic effect of these two agents creates a long-term, effective, and stable protective mechanism within the fiber, thus solving the technical problem of easy degradation of wear resistance and fatigue resistance of ultra-high molecular weight polyethylene fibers under long-term light exposure and cyclic loading in existing technologies.

[0008] In a preferred embodiment of a method for preparing wear-resistant and fatigue-resistant ultra-high molecular weight polyethylene fiber, the mass ratio of the triazine ultraviolet absorber to the hindered amine light stabilizer is 1:1.2 to 1:4.

[0009] It should be noted that the mass ratio of the triazine UV absorber to the hindered amine light stabilizer is controlled within the range of 1:1.2 to 1:4, so that the UV absorption and free radical capture processes form a synergistic matching relationship in the system, thereby achieving the continuous performance of the light stabilization effect without affecting the solubility stability of the system.

[0010] A preferred technical solution for preparing wear-resistant and fatigue-resistant ultra-high molecular weight polyethylene fiber, wherein the initial dispersion of the light-stabilized system in white oil by controlling the order of addition specifically includes: firstly, adding the triazine ultraviolet absorber 2-(4,6-diphenyl-1,3,5-triazine-2-yl)-5-hexoxy-phenol to white oil preheated to a set temperature, and completely dissolving it under stirring conditions to form a first solution; subsequently, while maintaining the system temperature and stirring conditions, adding the hindered amine light stabilizer bis(1-octoxy-2,2,6,6-tetramethyl-4-piperidine) sebacate to the first solution and continuing stirring.

[0011] It should be noted that by first adding triazine UV absorbers to preheated white oil and dissolving them completely under stirring, these light stabilizers with larger molecular weights and distinct aromatic ring structures can preferentially form a stable molecular-level dispersion in the solvent, thus creating a uniform solvent environment. Based on this, hindered amine light stabilizers are then introduced while maintaining the system temperature and stirring conditions. These stabilizers gradually diffuse and dissolve in the already homogeneous solution system, preventing local enrichment or self-aggregation of the two types of light stabilizers during the initial contact stage due to differences in dissolution rates and molecular interactions. This is beneficial to the initial dispersion stability of the light stabilizer system in the white oil and provides a uniform basis for the subsequent formation of the stabilizer solvent mother liquor.

[0012] In a preferred technical solution for the preparation method of wear-resistant and fatigue-resistant ultra-high molecular weight polyethylene fiber, in step S2, when the light-stabilizing system is introduced in the form of a solvent mother liquor, the amount added to the spinning solution is 0.1 to 1.5% of the mass of ultra-high molecular weight polyethylene.

[0013] It should be noted that introducing the light stabilizer system in the form of a solvent mother liquor and controlling its addition amount to 0.1-1.5% of the mass of ultra-high molecular weight polyethylene can achieve effective introduction and dispersion of the light stabilizer in the system without damaging the viscosity characteristics and forming stability of the spinning solution.

[0014] In a preferred embodiment of a method for preparing wear-resistant and fatigue-resistant ultra-high molecular weight polyethylene fiber, the shear rate of the high-shear dispersion treatment in step S2 is 1000–6000 s⁻¹. -1 The processing time is 5 to 30 minutes.

[0015] It should be noted that in step S2, the shear rate of the high-shear dispersion treatment is controlled between 1000 and 6000 s. -1 The processing time is 5 to 30 minutes, which allows the spinning solution in a high-temperature and high-viscosity state to obtain sufficient shear energy without significant degradation of polymer chain segments or structural damage. This promotes the full depolymerization and uniform dispersion of the photo-stable solvent mother liquor in the gel precursor system, and avoids uneven dispersion due to insufficient shear or structural degradation due to excessive shear. This provides a stable and consistent solution state for subsequent deoxidation treatment and spinning.

[0016] As a preferred technical solution for the preparation method of wear-resistant and fatigue-resistant ultra-high molecular weight polyethylene fiber, the controlled vacuum and inert gas synergistic deoxidation treatment in step S3 includes alternating vacuum extraction and introduction of nitrogen or argon gas.

[0017] It should be noted that by alternately applying vacuum extraction and introducing nitrogen or argon under high temperature and high viscosity conditions, the dissolved oxygen and residual gas content in the spinning solution can be gradually reduced, thus avoiding adverse effects on the polymer structure stability during subsequent extrusion and stretching processes.

[0018] In a preferred technical solution for the preparation method of wear-resistant and fatigue-resistant ultra-high molecular weight polyethylene fiber, the air gap length is 5 to 50 cm during the air gap gelation process in step S4.

[0019] It should be noted that controlling the air gap length within the range of 5 to 50 cm is beneficial for the spinning solution to complete the initial orientation and achieve stable gelation after extrusion, thereby providing a uniform structural basis for the subsequent solvent extraction and thermal stretching processes.

[0020] As a preferred technical solution for the preparation method of wear-resistant and fatigue-resistant ultra-high molecular weight polyethylene fiber, the heat setting treatment is carried out under controlled tension conditions, and the setting temperature is 130-160℃.

[0021] It should be noted that heat setting under controlled tension and within the range of 130–160°C can stabilize the internal stress state while maintaining the fiber orientation structure, thus avoiding structural shrinkage or performance fluctuations.

[0022] When the polyethylene fibers obtained by the above preparation method are used in ropes and cables, thanks to the uniform dispersion of the photo-stabilized system inside the fiber and the highly oriented and highly intact molecular chain structure formed in a low-oxygen environment, the ropes and cables can still maintain high strength stability and dimensional stability under long-term stress, repeated bending and outdoor light conditions. This significantly improves wear resistance, bending fatigue life and creep resistance, reduces performance degradation caused by photo-oxidation and structural degradation, thereby extending the service life of the ropes and cables and improving their safety and reliability in marine engineering, high-strength mooring and heavy-load traction applications. Detailed Implementation

[0023] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0024] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0025] Secondly, the term "an embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places throughout this specification does not necessarily refer to the same embodiment, nor is it a single embodiment or an embodiment selectively excluded from other embodiments.

[0026] Example Example 1

[0027] S1. 100 g of ultra-high molecular weight polyethylene powder with a weight average molecular weight of 3 million and 870 g of solvent white oil were added to a 5 L stainless steel reactor equipped with mechanical stirring, temperature control and nitrogen protection. Under the protection of nitrogen flow rate of 0.5 L / min, the temperature was slowly increased to 110°C at a rate of 2°C per minute, while stirring at a low speed of 200 r / min was turned on. The reaction was carried out for 2 hours for restricted swelling treatment, so that the ultra-high molecular weight polyethylene powder gradually absorbed the white oil and formed a uniform gel precursor system with semi-swollen chain segments and moderate viscosity. The whole process avoided excessively high viscosity caused by complete dissolution of polymer, and created good conditions for the uniform dispersion of light stabilizer in the later stage.

[0028] S2. First, prepare the light stabilizer solvent stock solution: Take 30 g of white oil, preheat it to 60℃, and slowly add 0.045 g of 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-hexyloxy-phenol while stirring at 300 r / min. Continue stirring for 30 minutes until completely dissolved to form a clear first solution. Maintaining the temperature at 60℃ and stirring, add 0.055 g of bis(1-octyloxy-2,2,6,6-tetramethyl-4-piperidine) sebacate and continue stirring for 30 minutes to obtain a stable stock solution. Slowly add this stock solution to the gel precursor system obtained in S1 using a metering pump, heat to 150℃, and disperse using a high-speed shear disperser at 1000 s⁻¹. -1 The shear rate was adjusted for 5 minutes to ensure complete and uniform dispersion of the light-stabilized system, ultimately yielding a spinning solution with a uniform and transparent appearance, free of bubbles and particles.

[0029] S3. The spinning solution is kept at a high temperature and high viscosity of 150°C and subjected to controlled vacuum and inert gas synergistic deoxygenation treatment: First, the vacuum pump is started to gradually reduce the system pressure to below 10 kPa and maintain it for 20 minutes to remove dissolved oxygen. Then, the vacuum is stopped and high-purity nitrogen (99.999% purity) is introduced for 5 minutes for gas replacement. This alternating operation is repeated 3 times. The entire process is carried out under nitrogen protection to ensure that the dissolved oxygen content in the spinning solution is below 1 ppm, providing a highly stable solution environment for subsequent extrusion and stretching.

[0030] S4. The deoxygenated spinning solution is heated to 160°C and extruded through a 0.8 mm diameter, 200-hole spinning head at a speed of 5 m / min. The extruded filaments immediately pass through a 5 cm long air gap to complete the initial gelation. Then, it is placed in a room temperature n-hexane extraction bath with a bath length of 3 m and an extraction time of 30 minutes until the solvent extraction rate reaches more than 99%. After hot air drying until the solvent residue is <0.5%, it is subjected to three-stage hot stretching. The first stage is stretched 5 times on a 100°C hot plate, the second stage is stretched 6 times on a 120°C hot plate, and the third stage is stretched 5 times on a 130°C hot plate, with a total stretching ratio of about 150 times. Finally, it is heat-set at 130°C with the tension precisely controlled at 0.5 cN / dtex for 10 minutes to obtain ultra-high molecular weight polyethylene fiber.

[0031] Example 2

[0032] S1. 100 g of ultra-high molecular weight polyethylene powder with a weight average molecular weight of 6 million and 870 g of solvent white oil were added together into a 5 L stainless steel reactor equipped with mechanical stirring, temperature control and nitrogen protection. Under the protection of nitrogen flow rate of 0.5 L / min, the temperature was slowly increased to 140°C at a rate of 1.5°C per minute, while stirring at a low speed of 150 r / min was turned on. The reaction was carried out for 1.5 hours for restricted swelling treatment, so that the ultra-high molecular weight polyethylene powder could fully absorb the white oil and form a uniform gel precursor system with high viscosity, mainly composed of semi-swollen chain segments. The temperature and time were precisely controlled throughout the process to avoid local dissolution of high molecular weight polymer or excessive relaxation of chain segments, and to provide a stable matrix environment for the uniform dispersion of high-addition light stabilizers.

[0033] S2. First, prepare the light stabilizer solvent mother liquor: Take 30 g of white oil, preheat it to 120℃, and slowly add 0.3 g of 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-hexyloxy-phenol while stirring at 400 r / min. Continue stirring for 20 minutes until it is completely dissolved to form a clear first solution. Keeping the temperature at 120℃ and stirring, add 1.2 g of bis(1-octyloxy-2,2,6,6-tetramethyl-4-piperidine) sebacate and continue stirring for 20 minutes to obtain a stable mother liquor. Slowly add this mother liquor to the gel precursor system obtained in S1 using a metering pump, heat it to 175℃, and treat it with a high-speed shear disperser at a shear rate of 6000 s⁻¹ for 30 minutes to completely depolymerize and uniformly disperse the light stabilizer system under high temperature and high shear, finally obtaining a spinning solution with a uniform and transparent appearance and no gel particles or bubbles.

[0034] S3. The spinning solution is kept at a high temperature and high viscosity of 175℃ and subjected to controlled vacuum and inert gas synergistic deoxygenation treatment: First, the vacuum pump is started to gradually reduce the system pressure to below 10 kPa and maintain it for 15 minutes to remove dissolved oxygen. Then, the vacuum is stopped and high-purity nitrogen (purity 99.999%) is introduced for 5 minutes for gas replacement. This alternating operation is repeated 4 times. The temperature fluctuation is strictly controlled to not exceed ±2℃ throughout the process to ensure that the dissolved oxygen content in the spinning solution is less than 1 ppm, so as to provide a highly stable solution environment for the subsequent high-stretching of high molecular weight fibers.

[0035] S4. The deoxygenated spinning solution is heated to 180°C and extruded through a 0.8 mm diameter, 200-hole spinning head at a speed of 4 m / min. The extruded filaments immediately pass through a 50 cm long air gap to achieve full gelation. Then, it is placed in a room temperature n-hexane extraction bath with a bath length of 3 m and an extraction time of 35 minutes until the solvent extraction rate reaches more than 99.5%. After hot air drying until the solvent residue is <0.3%, it undergoes three-stage hot stretching: the first stage is stretched 6 times on a 110°C hot plate, the second stage is stretched 7 times on a 130°C hot plate, and the third stage is stretched 6 times on a 150°C hot plate, for a total stretching ratio of approximately 250 times. Finally, it is heat-set at 160°C with the tension precisely controlled at 0.8 cN / dtex for 15 minutes to obtain ultra-high molecular weight polyethylene fibers.

[0036] Example 3

[0037] S1. 100 g of ultra-high molecular weight polyethylene powder with a weight average molecular weight of 4.5 million and 870 g of solvent white oil were added to a 5 L stainless steel reactor equipped with mechanical stirring, temperature control and nitrogen protection. Under the protection of nitrogen flow rate of 0.5 L / min, the temperature was slowly increased to 125°C at a rate of 1.8°C per minute, while stirring at a low speed of 180 r / min was turned on. The reaction was carried out for 1.8 hours for restricted swelling treatment, so that the ultra-high molecular weight polyethylene powder uniformly absorbed the white oil and formed a uniform gel precursor system with semi-swollen chain segments and moderate viscosity. The heating rate and stirring intensity were precisely controlled throughout the process to avoid local overheating or uneven dissolution, creating ideal matrix conditions for the uniform dispersion of the light stabilizer.

[0038] S2. First, prepare the light stabilizer solvent mother liquor: Take 30 g of white oil, preheat it to 90℃, and slowly add 0.229 g of 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-hexyloxy-phenol while stirring at 350 r / min. Continue stirring for 25 minutes until completely dissolved to form a clear first solution. Maintaining 90℃ and stirring, add 0.571 g of bis(1-octyloxy-2,2,6,6-tetramethyl-4-piperidine) sebacate and continue stirring for 25 minutes to obtain a stable mother liquor. Slowly add this mother liquor to the gel precursor system obtained in S1 using a metering pump, heat to 162℃, and treat with a high-speed shear disperser (rotor-stator structure) at a shear rate of 3500 s⁻¹ for 17 minutes to completely and uniformly disperse the light stabilized system, finally obtaining a uniform, transparent spinning solution without bubbles or particles.

[0039] S3. The spinning solution is kept at a high temperature and high viscosity of 162℃ and subjected to controlled vacuum and inert gas synergistic deoxygenation treatment: First, the vacuum pump is started to gradually reduce the system pressure to below 10 kPa and maintain it for 20 minutes to remove dissolved oxygen. Then, the vacuum is stopped and high-purity nitrogen (purity 99.999%) is introduced for 5 minutes for gas replacement. This alternating operation is repeated 3 times. The entire process is carried out under nitrogen protection to ensure that the dissolved oxygen content in the spinning solution is below 1 ppm, providing a highly stable solution environment for subsequent extrusion and stretching.

[0040] S4. The deoxygenated spinning solution is heated to 170°C and extruded through a 0.8 mm diameter, 200-hole spinning head at a speed of 4.5 m / min. The extruded filaments immediately pass through a 27 cm long air gap to complete the initial gelation. Then, it is placed in a room temperature n-hexane extraction bath with a bath length of 3 m and an extraction time of 32 minutes until the solvent extraction rate reaches more than 99.2%. After hot air drying until the solvent residue is <0.4%, it is subjected to three-stage hot stretching. The first stage is stretched 5.5 times on a hot plate at 105°C, the second stage is stretched 6.5 times on a hot plate at 125°C, and the third stage is stretched 5.5 times on a hot plate at 140°C, with a total stretching ratio of about 200 times. Finally, it is heat-set at 145°C with the tension precisely controlled at 0.6 cN / dtex for 12 minutes to obtain ultra-high molecular weight polyethylene fiber.

[0041] Example 4

[0042] S1. 100 g of ultra-high molecular weight polyethylene powder with a weight average molecular weight of 5 million and 870 g of solvent white oil were added to a 5 L stainless steel reactor equipped with mechanical stirring, temperature control and nitrogen protection. Under the protection of nitrogen flow rate of 0.5 L / min, the temperature was slowly increased to 130℃ at a rate of 1.7℃ per minute, while stirring at a low speed of 200 r / min was turned on. The reaction was carried out for 2 hours for restricted swelling treatment, so that the ultra-high molecular weight polyethylene powder gradually absorbed the white oil and formed a uniform gel precursor system with semi-swollen chain segments and moderate viscosity. The whole process avoided the excessively high viscosity caused by complete dissolution of polymer, and created good conditions for the uniform dispersion of subsequent light stabilizers.

[0043] S2. First, prepare the light stabilizer solvent stock solution: Take 30 g of white oil, preheat it to 100℃, and slowly add 0.125 g of 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-hexyloxy-phenol while stirring at 320 r / min. Continue stirring for 25 minutes until completely dissolved to form a clear first solution. Maintaining 100℃ and stirring, add 0.375 g of bis(1-octyloxy-2,2,6,6-tetramethyl-4-piperidine) sebacate and continue stirring for 25 minutes to obtain a stable stock solution. Slowly add this stock solution to the gel precursor system obtained in S1 using a metering pump, heat to 160℃, and disperse using a high-speed shear disperser (rotor-stator structure) at 2000 s⁻¹. -1 The shear rate was adjusted for 15 minutes to ensure complete and uniform dispersion of the light-stabilized system, ultimately yielding a spinning solution with a uniform and transparent appearance, free of bubbles and particles.

[0044] S3. The spinning solution is kept at a high temperature and high viscosity of 160℃ and subjected to controlled vacuum and inert gas synergistic deoxygenation treatment: First, the vacuum pump is started to gradually reduce the system pressure to below 10 kPa and maintain it for 18 minutes to remove dissolved oxygen. Then, the vacuum is stopped and high-purity nitrogen (99.999% purity) is introduced for 5 minutes for gas replacement. This alternating operation is repeated 3 times. The entire process is carried out under nitrogen protection to ensure that the dissolved oxygen content in the spinning solution is below 1 ppm, providing a highly stable solution environment for subsequent extrusion and stretching.

[0045] S4. The deoxygenated spinning solution is heated to 175°C and extruded through a 0.8 mm diameter, 200-hole spinning head at a speed of 4.8 m / min. The extruded filaments immediately pass through a 30 cm long air gap to complete the initial gelation. Then, it is placed in a room temperature n-hexane extraction bath with a bath length of 3 m and an extraction time of 33 minutes until the solvent extraction rate reaches more than 99.3%. After hot air drying until the solvent residue is <0.4%, it is subjected to three-stage hot stretching. The first stage is stretched 6 times on a hot plate at 108°C, the second stage is stretched 6 times on a hot plate at 128°C, and the third stage is stretched 6 times on a hot plate at 145°C, with a total stretching ratio of about 220 times. Finally, it is heat-set at 150°C with the tension precisely controlled at 0.7 cN / dtex for 13 minutes to obtain ultra-high molecular weight polyethylene fiber.

[0046] Comparison Example

[0047] Compare with Example 1 Compared with Example 1, the difference is that no light stabilizer solvent stock solution is prepared or added in step S2, and the gel precursor system obtained in S1 is directly heated to 150°C and heated at 1000 s. -1 The spinning solution was obtained by shearing at a rate of 5 minutes, and the other steps were exactly the same.

[0048] Compare with Example 2 Compared with Example 1, the difference is that in step S2, the triazine UV absorber and hindered amine light stabilizer of the present invention are not used when preparing the mother liquor. Instead, 0.1 g of the conventional hindered phenolic antioxidant pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (Irganox 1010, equivalent to 0.1% of the mass of UHMWPE) is added. The mother liquor preparation temperature is still 60°C. The antioxidant is added first and dissolved for 30 minutes, and then stirred for another 30 minutes to obtain the mother liquor. The remaining operations (addition order, shearing, deoxygenation, etc.) are exactly the same as in Example 1.

[0049] Compare with Example 3 Compared with Example 1, the difference is that in step S2, no solvent stock solution is prepared. Instead, 0.045 g of triazine UV absorber and 0.055 g of hindered amine light stabilizer are directly added in powder form to the gel precursor system obtained in S1 in one step, and then the temperature is raised to 150°C and heated at 1000 s. -1 The shear rate was treated for 5 minutes; all other steps were exactly the same as in Example 1.

[0050] Compare with Example 4 Compared with Example 1, the difference is that step S3 is omitted, and the spinning solution obtained in S2 is directly subjected to subsequent treatments such as extrusion molding and air gap gelation in S4; all other steps (including the amount of light-stabilizing system added, the order of mother liquor preparation, shear dispersion, etc.) are exactly the same as in Example 1.

[0051] Performance testing methods

[0052] 1. Tensile strength and initial modulus: The tensile strength (cN / dtex) and initial modulus (cN / dtex) of the fiber were tested using an electronic universal testing machine at a tensile rate of 250 mm / min under the conditions of 23℃ and 65%RH, in accordance with GB / T 19975-2005 standard.

[0053] 2. Abrasion resistance: Using a yarn abrasion tester, the fibers were subjected to cross-friction with themselves under a tension of 1.0 cN / dtex, and the number of cycles until breakage was recorded.

[0054] 3. Bending fatigue life: Using a bending fatigue testing machine, the fiber strength was repeatedly bent under the conditions of bending radius of 5 mm, load of 0.5 cN / dtex and frequency of 1 Hz, and the number of cycles when the fiber strength decreased by 30% was recorded.

[0055] 4. Strength retention rate after UV accelerated aging: The fiber was placed in a xenon arc lamp accelerated aging chamber with a black panel temperature of 63℃ and an irradiation intensity of 0.55 W / m. 2 After irradiation at 340 nm for 500 h, tensile strength was tested according to GB / T 19975, and retention rate (%) was calculated.

[0056] 5. Creep performance: Under constant load of 0.3 cN / dtex and temperature of 23℃, the elongation (%) of the fiber was continuously recorded for 24 h, 100 h and 1000 h using a creep tester.

[0057] Table 1

[0058] As can be seen from Examples 1 to 4 and Table 1, the tensile strength of the ultra-high molecular weight polyethylene fibers obtained in the embodiments of the present invention is 5.8–6.4 cN·dtex. -1 The initial modulus is 110–122 cN·dtex. -1The wear resistance cycle count is 18,500–23,800 cycles, the flexural fatigue life is 52,000–66,500 cycles, and the strength retention rate after UV aging is 87.5–92.1%. The creep elongation at 24 h, 100 h, and 1000 h is stably controlled within the ranges of 0.51–0.62%, 0.74–0.88%, and 1.10–1.35%, respectively. Overall, it exhibits synergistic characteristics of high strength, high wear resistance, high fatigue resistance, and low creep, indicating that within the process and composition range defined by this invention, fiber products with excellent comprehensive performance and small fluctuations can be stably obtained.

[0059] As can be seen from Example 1, Comparative Example 1, and Table 1, in Comparative Example 1, where no photostable system was introduced, the fiber tensile strength was only 4.6 cN·dtex. -1 The wear resistance cycle count and flexural fatigue life decreased to 9200 and 24000 cycles, respectively, and the strength retention rate after UV aging was only 63.4%, while the creep elongation at 1000 h was as high as 3.42%; whereas the corresponding indicators in Example 1 were significantly improved. In Comparative Example 1, the polyethylene molecular chains are prone to photo-oxidation and thermal oxidation reactions during processing and service, leading to main chain breakage and orientation structure destruction. However, Example 1, by introducing a synergistic system of triazine UV absorbers and hindered amine light stabilizers, effectively inhibits free radical generation and chain degradation reactions, thereby significantly improving the long-term mechanical stability of the fiber.

[0060] As can be seen from Example 1, Comparative Example 2, and Table 1, although Comparative Example 2 introduced a traditional hindered phenolic antioxidant, its tensile strength, abrasion resistance, and fatigue life were improved compared to Comparative Example 1, but were still significantly lower than those of Example 1. Specifically, the strength retention rate after UV aging was only 68.2%, and the creep elongation at 1000 h was still as high as 3.10%. Traditional antioxidants mainly target free radicals during thermal oxidation and are difficult to effectively inhibit UV-induced photo-oxidation reactions. In contrast, the synergistic system of triazine UV absorbers and hindered amine light stabilizers used in Example 1 can simultaneously achieve UV absorption and continuous free radical capture, mechanistically blocking the photo-oxidation chain reaction, thus exhibiting a significant advantage in durability.

[0061] As can be seen from Example 1, Comparative Example 3, and Table 1, although Comparative Example 3 also used triazine UV absorbers and hindered amine light stabilizers, its wear resistance cycle count and flexural fatigue life were only 11,200 and 30,000 cycles, respectively, significantly lower than those of Example 1. In Comparative Example 3, the light stabilizer was directly added to the high-viscosity gel system in powder form, which easily led to local enrichment and uneven dispersion, forming structurally weak areas. In contrast, Example 1, by first preparing the stabilizer solvent mother liquor and controlling the order of addition, enabled the light stabilizer system to achieve molecular-level uniform dispersion in the pregelation stage, thereby significantly improving the overall structural consistency and service stability of the fiber.

[0062] Combining Example 1, Comparative Example 4, and Table 1, it can be seen that Comparative Example 4, which omits the controlled vacuum and inert gas synergistic deoxidation treatment, has a tensile strength of only 1.47 cN·dtex. -1 The strength retention and creep performance also deteriorated significantly after UV aging, with the creep elongation reaching 3.30% after 1000 h. Failure to effectively remove dissolved oxygen under high temperature and high viscosity conditions accelerates the oxidative degradation of polyethylene molecular chains and amplifies structural defects during stretching and orientation. In contrast, Example 1 significantly reduced the dissolved oxygen content in the system through deoxidation treatment, providing a stable chemical environment for subsequent high-strength stretching and long-term service, thereby significantly improving the overall mechanical and durability properties of the fiber.

[0063] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing wear-resistant and fatigue-resistant ultra-high molecular weight polyethylene fiber, characterized in that, Includes the following steps: S1. Mix ultra-high molecular weight polyethylene powder with a weight average molecular weight of 3 million to 6 million with white oil, and subject it to restricted swelling treatment at 110 to 140°C to form a gel precursor system with semi-swollen segments as the main component of ultra-high molecular weight polyethylene. S2. The light-stabilized system is introduced into the gel precursor system in the form of a solvent mother liquor, and a high-shear dispersion treatment is applied at 150-175℃ to obtain a uniform and transparent spinning solution. S3. The spinning solution is subjected to controlled vacuum and inert gas synergistic deoxidation treatment under high temperature and high viscosity conditions; S4. The deoxygenated spinning solution is subjected to extrusion molding, air gap gelation, solvent extraction, multi-stage hot stretching and heat setting treatment in sequence to obtain ultra-high molecular weight polyethylene fiber.

2. The preparation method according to claim 1, characterized in that, The photostable system is initially dispersed in white oil by controlling the order of addition. The resulting system is then heated and continuously stirred at 60–120°C to obtain a stabilizer solvent mother liquor with a predetermined mass concentration. The photostable system includes a triazine UV absorber and a hindered amine photostable agent. The triazine UV absorber is 2-(4,6-diphenyl-1,3,5-triazine-2-yl)-5-hexoxy-phenol, and the hindered amine photostable agent is bis(1-octyloxy-2,2,6,6-tetramethyl-4-piperidine) sebacate.

3. The preparation method according to claim 2, characterized in that, The mass ratio of the triazine ultraviolet absorber to the hindered amine light stabilizer is 1:1.2 to 1:

4.

4. The preparation method according to claim 2, characterized in that, The process of controlling the order of addition to initially disperse the photostable system in white oil specifically includes: first, adding the triazine-based ultraviolet absorber 2-(4,6-diphenyl-1,3,5-triazine-2-yl)-5-hexoxy-phenol to white oil preheated to a set temperature, and then completely dissolving it under stirring conditions to form a first solution; subsequently, while maintaining the system temperature and stirring conditions, adding the hindered amine-based photostable agent bis(1-octyloxy-2,2,6,6-tetramethyl-4-piperidine) sebacate to the first solution and continuing stirring.

5. The preparation method according to claim 1, characterized in that, In step S2, when the light-stabilized system is introduced in the form of a solvent mother liquor, the amount added to the spinning solution is 0.1 to 1.5% of the mass of ultra-high molecular weight polyethylene.

6. The preparation method according to claim 1, characterized in that, The shear rate of the high-shear dispersion treatment in step S2 is 1000–6000 s. -1 The processing time is 5 to 30 minutes.

7. The preparation method according to claim 1, characterized in that, The controlled vacuum and inert gas synergistic deoxygenation process described in step S3 includes alternating vacuum extraction and the introduction of nitrogen or argon gas.

8. The preparation method according to claim 1, characterized in that, During the air gap gelation process described in step S4, the length of the air gap is 5 to 50 cm.

9. The preparation method according to claim 1, characterized in that, The heat setting process is carried out under controlled tension conditions, and the setting temperature is 130–160°C.

10. The application of a polyethylene fiber prepared according to the preparation method of claim 1 in ropes and cables.

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