High-strength modified polyethylene composite fiber and method for manufacturing the same

Abstract

This invention discloses a high-strength modified polyethylene composite fiber and its preparation method, belonging to the field of fiber material technology. It uses carboxylated mesoporous silica microspheres as a matrix, coated with graphene sheets, and then grafted with hydroxyethyl methacrylate to obtain functionalized graphene / mesoporous silica microspheres. These microspheres, used as fillers in ship cables, can reduce the overall weight of the cables. The relative slippage between the graphene sheets and the mesoporous silica microspheres disperses stress and improves the strength of the polyethylene composite fiber. Furthermore, the esterification of the graphene / mesoporous silica microspheres with hydroxyethyl methacrylate introduces hydrophobic alkane long chains through graft modification, resulting in good compatibility with white oil. The steric hindrance effect prevents the microspheres from agglomerating, thus ensuring more uniform and stable dispersion in the white oil.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of fiber materials, and particularly relates to a high-strength modified polyethylene composite fiber and a preparation method thereof. BACKGROUND

[0002] The ultra-high molecular weight polyethylene fiber is a high-performance fiber prepared from polyethylene with a relative molecular weight of more than 1.5 million, and has excellent mechanical properties, small density, good weather resistance, chemical corrosion resistance, low temperature resistance, bending resistance, cutting resistance, impact resistance, low electrical conductivity, high transmittance to medium wavelength infrared, and certain waterproofness, and is widely used in military equipment, aerospace, marine engineering, safety protection, transportation, sports equipment, biological medicine, home textile products and other special fields.

[0003] In recent years, with the increasing attention to the development of marine resources, the application demand of the ultra-high molecular weight polyethylene fiber rope has increased sharply, the specific strength of the ultra-high molecular weight polyethylene fiber is the highest among the current high-performance fibers, and the breaking strength thereof can reach 1.5 times or even higher than that of a steel cable with the same diameter, and is used for mooring super tankers, marine operating platforms, lighthouse fixed anchor ropes, port tugboats and the like, solves the fracture risk caused by the corrosion of the steel cable and the degradation of the nylon cable, guarantees the safety of the ship and personnel, and provides greater flexibility for ship design and operation.

[0004] At present, as a new type of material, the ultra-high molecular weight polyethylene fiber has been widely used in fisheries and ships. As a ship cable, the ultra-high molecular weight polyethylene fiber itself has the characteristics of high modulus and low elongation, which means that it has poor deformation ability when stressed, and in long-term operation, the ship cable is prone to produce microcracks in the fiber inside due to small-radius bending at sharp edges and the like, so that the ship cable is prone to damage in long-term service, and the service life is significantly reduced. SUMMARY

[0005] The purpose of the application is to provide a high-strength modified polyethylene composite fiber and a preparation method thereof, so as to prepare a modified polyethylene composite fiber with high strength and high toughness by taking the functionalized graphene / mesoporous silica microspheres with a core-shell structure and the characteristics of "hard inside and soft outside" as fillers, and the graphene layers and the mesoporous silica microspheres of the filler particles will produce relative slip, so as to disperse stress and improve the bending resistance and service life of the ship cable prepared from the polyethylene composite fiber.

[0006] The purpose of the application can be achieved by the following technical scheme.

[0007] A preparation method of a high-strength modified polyethylene composite fiber, comprising the following steps:

[0008] Step one: through the amidation reaction of the carboxyl group of the carboxylated mesoporous silica microspheres and the amino group of γ-aminopropyl triethoxysilane, modified mesoporous silica microspheres are obtained; through the chemical bonding of the silicon hydroxyl group contained in the modified mesoporous silica microspheres and the hydroxyl group on the surface of graphene, graphene / mesoporous silica microspheres are obtained.

[0009] Step two: through the chemical bonding of the edge carboxyl group of the graphene / mesoporous silica microspheres and the hydroxyl group in hydroxyethyl methacrylate under the action of a dehydrating agent and a catalyst, functionalized graphene / mesoporous silica microspheres are obtained.

[0010] Step three: with ultra-high molecular weight polyethylene resin, functionalized graphene / mesoporous silica microspheres and antioxidant 1076 as raw materials, high-strength modified polyethylene composite fibers are obtained by spinning through a twin-screw extruder.

[0011] Further, the specific preparation steps of the modified mesoporous silica microspheres are as follows:

[0012] Carboxylated mesoporous silica microspheres and ethanol are added to a reaction kettle, stirred at 20-25℃ and 500-600r / min for 10-20min under a nitrogen atmosphere, then N,N-diisopropylethylamine and O-benzotriazole-tetramethyl urea hexafluorophosphate are added and continue to stir for 3-5min, then γ-aminopropyl triethoxysilane is added and continue to stir for 1-2h, filter, wash the product with ethanol and isopropyl alcohol for 2-3 times respectively, and vacuum dry at 60-80℃ for 1-2h to obtain modified mesoporous silica microspheres.

[0013] Further, the amount ratio of carboxylated mesoporous silica microspheres, ethanol, N,N-diisopropylethylamine, O-benzotriazole-tetramethyl urea hexafluorophosphate and γ-aminopropyl triethoxysilane is 20-30g:1-2L:0.125-0.15g:0.1-0.5g:15-20mL.

[0014] Further, the specific preparation steps of the graphene / mesoporous silica microspheres are as follows:

[0015] Modified mesoporous silica microspheres and an ethanol solution with a mass fraction of 50-55% are added to a reaction kettle, stirred at 20-25℃ and 500-600r / min for 10-20min, the pH value is adjusted to 3-4 with NaOH, then graphene is added and continue to stir for 2-3h, filter, wash the product with anhydrous ethanol and deionized water for 2-3 times respectively, and vacuum dry at 60-80℃ for 1-2h to obtain graphene / mesoporous silica microspheres.

[0016] Further, the amount ratio of modified mesoporous silica microspheres, ethanol solution and graphene is 15-20g:3-4L:12-15g.

[0017] Further, the functionalized graphene / mesoporous silica microspheres are prepared according to the following steps:

[0018] The graphene / mesoporous silica microspheres, hydroxyethyl methacrylate and tetrahydrofuran are added into a reaction kettle, stirred at 20-25 DEG C and 500 r / min for 20-30 min, then anhydrous magnesium sulfate as a dehydrating agent and p-toluenesulfonic acid monohydrate as a catalyst are added, continue to stir for 24-26 h, filter, the filter cake is washed with deionized water and anhydrous ethanol for 2-4 times respectively, vacuum dried at 60-80 DEG C for 1-2 h, to obtain the functionalized graphene / mesoporous silica microspheres.

[0019] Further, the amount ratio of the graphene / mesoporous silica microspheres, hydroxyethyl methacrylate, tetrahydrofuran, anhydrous magnesium sulfate and p-toluenesulfonic acid monohydrate is 12-14 g:4-5 g:120-140 mL:0.2-0.4 g:0.3-0.5 g.

[0020] Further, the high-strength modified polyethylene composite fiber is prepared according to the following steps:

[0021] The functionalized graphene / mesoporous silica microspheres and white oil are placed in a high-speed homogenizing mixer, mixed at 3000-3200 r / min for 30-40 min, then the ultra-high molecular weight polyethylene resin with a molecular weight of 6 million and antioxidant 1076 are added, continue to mix for 30-40 min, the product is spun through a double screw extruder, the spinning speed is 80-120 m / min at 180-200 DEG C, and the original wire is placed and hot drawn at 95-100 DEG C, to obtain the high-strength modified polyethylene composite fiber with a diameter of 60-80 mu m.

[0022] Further, the amount ratio of the functionalized graphene / mesoporous silica microspheres, white oil, ultra-high molecular weight polyethylene resin and antioxidant 1076 is 5-6 g:200-300 mL:100-120 g:2-3 g.

[0023] The beneficial effects of the present application are:

[0024] 1. The high-strength modified polyethylene composite fiber prepared by the present application uses carboxylated mesoporous silica microspheres as the matrix, the surface is coated with graphene sheet layer, and then hydroxyethyl methacrylate is grafted to obtain functionalized graphene / mesoporous silica microspheres, which are used as fillers to prepare modified polyethylene composite fibers applied to ship cables. The core-shell structure of "hard inside and soft outside" between the graphene sheet layer and the mesoporous silica microspheres will produce relative slip, effectively disperse stress, play a role in deflecting cracks, reduce the crack generation of the polymer part of the high molecular weight polyethylene fiber, thereby helping to improve the bending resistance and service life of the ship cable.

[0025] 2. The simple inorganic filler is poor in compatibility with the ultra-high molecular polyethylene, the functionalized graphene / mesoporous silica microspheres in the application are esterified with the hydroxyl groups in the hydroxyethyl methacrylate through the edge carboxyl groups in the graphene / mesoporous silica microspheres, the graft modification of the hydroxyethyl methacrylate introduces the hydrophobic alkane long chain, the compatibility with the white oil is good, the steric hindrance effect prevents the microspheres from approaching and gathering, and the microspheres are more uniformly and stably dispersed in the white oil, and after spinning of the ultra-high molecular weight polyethylene resin, the microspheres can be better dispersed in the high-strength modified polyethylene composite fiber.

[0026] 3. The functionalized graphene / mesoporous silica microspheres in the application have the characteristics of hollow and light weight with the carboxylated mesoporous silica microspheres as the matrix, and the graphene can significantly increase the wear resistance of the polyethylene composite fiber. The functionalized graphene / mesoporous silica microspheres can effectively reduce the weight of the ship cable and increase the wear resistance of the ship cable, and have a good application prospect. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the application will be clearly and completely described below in combination with the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the application.

[0028] Embodiment 1: A preparation method of a high-strength modified polyethylene composite fiber, comprising the following steps:

[0029] S1: 20 g of carboxylated mesoporous silica microspheres with a particle size of 1 μm and 1 L of ethanol are added into a reaction kettle, and stirred at 20 ℃ and 500 r / min under a nitrogen atmosphere for 10 min, then 0.125 g of N,N-diisopropylethylamine and 0.1 g of O-benzotriazole-tetramethyl urea hexafluorophosphate are added and continue to stir for 3 min, then 15 mL of γ-aminopropyl triethoxysilane is added, and continue to stir for 1 h, then the product is filtered, washed with ethanol and isopropyl alcohol for 2 times respectively, and vacuum dried at 60 ℃ for 1 h to obtain modified mesoporous silica microspheres.

[0030] The amide reaction occurs between the carboxyl groups carried on the surface of the carboxylated mesoporous silica microspheres and the amino groups of γ-aminopropyl triethoxysilane under the activation of N,N-diisopropylethylamine and O-benzotriazole-tetramethyl urea hexafluorophosphate, so that the silane groups are retained, and the modified mesoporous silica microspheres are obtained.

[0031] S2: 15 g of modified mesoporous silica microspheres and 3 L of 50% ethanol solution were added to a reaction kettle, stirred at 20°C and 500 r / min for 10 min, the pH value was adjusted to 3 with NaOH, then 12 g of graphene was added, and the stirring reaction was continued for 2 h. The product was filtered, washed with anhydrous ethanol and deionized water for 2 times respectively, and vacuum dried at 60°C for 1 h to obtain graphene / mesoporous silica microspheres.

[0032] S3: 12 g of graphene / mesoporous silica microspheres, 4 g of hydroxyethyl methacrylate and 120 mL of tetrahydrofuran were added to a reaction kettle, stirred at 20°C and 500 r / min for 20 min, then 0.2 g of anhydrous magnesium sulfate as a dehydrating agent and 0.3 g of p-toluenesulfonic acid monohydrate as a catalyst were added, and the stirring was continued for 24 h. The filter cake was washed with deionized water and anhydrous ethanol for 2 times respectively, and vacuum dried at 60°C for 1 h to obtain functionalized graphene / mesoporous silica microspheres.

[0033] The modified mesoporous silica microspheres were hydrolyzed in the ethanol solution to generate silicon hydroxyl groups which were bonded to the hydroxyl groups on the surface of graphene, thereby obtaining graphene / mesoporous silica microspheres.

[0034] S4: 5 g of functionalized graphene / mesoporous silica microspheres and 200 mL of white oil were placed in a high-speed homogenizing mixer, mixed at 3000 r / min for 30 min, then 100 g of ultrahigh molecular weight polyethylene resin with a molecular weight of 6 million and 2 g of antioxidant 1076 were added, and the mixing was continued for 30 min. The product was spun through a double-screw extruder at 180°C with a spinning speed of 80 m / min, and after the original yarn was placed and hot drawn at 95°C, high-strength modified polyethylene composite fibers with a diameter of 60 μm were obtained.

[0035] The graphene in the graphene / mesoporous silica microspheres contains edge carboxyl groups, which are esterified with the hydroxyl groups in the hydroxyethyl methacrylate under the action of a dehydrating agent and a catalyst, thereby obtaining functionalized graphene / mesoporous silica microspheres.

[0036] Example 2: A method for preparing high-strength modified polyethylene composite fibers, comprising the following steps:

[0037] S1: 25 g of carboxylated mesoporous silica microspheres with a particle size of 1.5 μm and 1.5 L of ethanol were added to a reaction kettle, stirred at 22.5 °C and 550 r / min for 15 min under a nitrogen atmosphere, then 0.1375 g of N,N-diisopropylethylamine and 0.3 g of O-benzotriazole-tetramethyl urea hexafluorophosphate were added and stirred for 4 min, then 17.5 mL of γ-aminopropyl triethoxysilane was added and the reaction was continued for 1.5 h, the product was filtered, washed with ethanol and isopropyl alcohol for 2.5 times respectively, and vacuum dried at 70 °C for 1.5 h to obtain modified mesoporous silica microspheres.

[0038] S2: 17.5 g of modified mesoporous silica microspheres and 3.5 L of an ethanol solution with a mass fraction of 52.5% were added to a reaction kettle, stirred at 22.5 °C and 550 r / min for 15 min, the pH value was adjusted to 3.5 with NaOH, then 13.5 g of graphene was added and the reaction was continued for 2.5 h, the product was filtered, washed with anhydrous ethanol and deionized water for 2.5 times respectively, and vacuum dried at 70 °C for 1.5 h to obtain graphene / mesoporous silica microspheres.

[0039] S3: 13 g of graphene / mesoporous silica microspheres, 4.5 g of hydroxyethyl methacrylate and 130 mL of tetrahydrofuran were added to a reaction kettle, stirred at 22.5 °C and 500 r / min for 25 min, then 0.3 g of anhydrous magnesium sulfate as a dehydrating agent and 0.4 g of p-toluenesulfonic acid monohydrate as a catalyst were added, and the stirring was continued for 25 h, the filter cake was washed with deionized water and anhydrous ethanol for 3 times respectively, and vacuum dried at 70 °C for 1.5 h to obtain functionalized graphene / mesoporous silica microspheres.

[0040] S4: 5.5 g of functionalized graphene / mesoporous silica microspheres and 250 mL of white oil were placed in a high-speed homogenizing mixer, mixed at 3100 r / min for 35 min, then 110 g of ultra-high molecular weight polyethylene resin with a molecular weight of 6 million and 2.5 g of antioxidant 1076 were added, and the mixing was continued for 35 min, the product was spun through a double-screw extruder at 190 °C and a spinning speed of 100 m / min, and after standing and hot drawing at 97.5 °C, high-strength modified polyethylene composite fibers with a diameter of 70 μm were obtained.

[0041] Example 3: A preparation method of a high-strength modified polyethylene composite fiber, comprising the following steps:

[0042] S1: 30 g of carboxylated mesoporous silica microspheres with a particle size of 2 μm and 2 L of ethanol were added to a reaction kettle, stirred at 25 °C and 600 r / min for 20 min under a nitrogen atmosphere, then 0.15 g of N,N-diisopropylethylamine and 0.5 g of O-benzotriazole-tetramethyluronium hexafluorophosphate were added and stirred for 5 min, then 20 mL of γ-aminopropyltriethoxysilane was added and the reaction was continued to stir for 2 h, the product was filtered, washed with ethanol and isopropyl alcohol for 3 times respectively, and vacuum dried at 80 °C for 2 h to obtain modified mesoporous silica microspheres.

[0043] S2: 20 g of modified mesoporous silica microspheres and 4 L of 55% mass fraction ethanol solution were added to a reaction kettle, stirred at 25 °C and 600 r / min for 20 min, the pH value was adjusted to 4 with NaOH, then 15 g of graphene was added and the reaction was continued to stir for 3 h, the product was filtered, washed with anhydrous ethanol and deionized water for 3 times respectively, and vacuum dried at 80 °C for 2 h to obtain graphene / mesoporous silica microspheres.

[0044] S3: 14 g of graphene / mesoporous silica microspheres, 5 g of hydroxyethyl methacrylate and 140 mL of tetrahydrofuran were added to a reaction kettle, stirred at 25 °C and 500 r / min for 30 min, then 0.4 g of anhydrous magnesium sulfate as a dehydrating agent and 0.5 g of p-toluenesulfonic acid monohydrate as a catalyst were added, and the reaction was continued to stir for 26 h, the filter cake was washed with deionized water and anhydrous ethanol for 4 times respectively, and vacuum dried at 80 °C for 2 h to obtain functionalized graphene / mesoporous silica microspheres.

[0045] S4: 6 g of functionalized graphene / mesoporous silica microspheres and 300 mL of white oil were placed in a high-speed homogenizing mixer, mixed at 3200 r / min for 40 min, then 120 g of ultrahigh molecular weight polyethylene resin with a molecular weight of 6 million and 3 g of antioxidant 1076 were added, and the mixing was continued for 40 min, the product was spun through a twin-screw extruder, the spinning was carried out at 200 °C and a spinning speed of 120 m / min, and after the original yarn was placed and hot-drawing at 100 °C, high-strength modified polyethylene composite fibers with a diameter of 80 μm were obtained.

[0046] Comparative Example 1: On the basis of Example 3, the modified mesoporous silica microspheres in step S2 were replaced by the raw material carboxylated mesoporous silica microspheres in step S1, and the rest remained unchanged to prepare high-strength modified polyethylene composite fibers.

[0047] Comparative Example 2: On the basis of Example 3, the carboxylated mesoporous silica microspheres in step S1 were replaced by commercially available carboxylated silica microspheres, and the rest remained unchanged to prepare high-strength modified polyethylene composite fibers.

[0048] Comparative Example 3: On the basis of Example 3, the functionalized graphene / mesoporous silica microspheres in step S4 were replaced with the graphene / mesoporous silica microspheres prepared in step S2, and the rest remained unchanged, to prepare high-strength modified polyethylene composite fibers.

[0049] The carboxylated mesoporous silica microspheres were purchased from Tianjin Xidian Chemical Technology Co., Ltd., CAS No. 60676-86-0.

[0050] O-benzotriazole-tetramethyl urea hexafluorophosphate was purchased from Beijing Huawei Ruike Chemical Co., Ltd.

[0051] The high-strength modified polyethylene composite fibers prepared in Examples 1-3 and Comparative Examples 1-3 were tested for performance:

[0052] 1. Anti-cutting grade test: The test was performed in accordance with the standard of ANSI / ISEA2016.

[0053] 2. Breaking strength test: The high-strength modified polyethylene composite fibers were divided into three pieces of 10 cm x 3 cm strip-shaped samples, weighed to obtain a mass M, and the fiber linear density Tt = M / L (length) was calculated. The breaking strength P0 was calculated using the formula P0 = P / Tt, and the higher the breaking strength, the stronger the tensile strength.

[0054] 3. Abrasion resistance test: The abrasion resistance of the high-strength modified polyethylene composite fibers was tested in accordance with FZ / T50025-2014 "Test Method for Abrasion Resistance of Ultra-high Molecular Weight Polyethylene Filaments". The friction roller of the reciprocating fiber abrasion tester had a diameter of 10 mm and was coated with W20(02) metallographic sandpaper. The abrasive particles on the surface of the sandpaper were SiC, and the abrasive particle size was 20 μm. During the friction process, the friction roller made a reciprocating motion with a reciprocating distance of 25 mm and a reciprocating frequency of 95 times / min -1 . During the friction test, the fiber tension was controlled at 0.45 cN·dtex -1 , and the wrapping angle of the fiber around the friction roller was 110°. The maximum number of friction times (Nf) of the fiber was defined as the number of reciprocations of the friction roller from the start of the fiber abrasion resistance test to the failure of the fiber due to abrasion and breakage. The test environment temperature was controlled at 25°C and the humidity was about 60%.

[0055] 4. Density test: The density of the high-strength modified polyethylene composite fibers was tested in accordance with ASTM D4883-08 "Standard Test Method for Determining the Density of Polyethylene by Ultrasonic Technique" to evaluate the lightweight property.

[0056] The results are shown in Table 1:

[0057] Table 1 Performance test table of high-strength modified polyethylene composite fibers

[0058] Item Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Cut resistance rating A4 A5 A5 A3 A2 A3 Breaking strength (MPa) 51.6 51.9 52.3 48.5 45.2 48.1 Wear resistance Nf (cycles) 11689 11742 11816 8234 10125 8015 Density (g / cm 3 ) 0.969 0.961 0.953 0.985 1.012 0.994

[0059] As can be seen from Table 1, the cut resistance, breaking strength and wear resistance of the high-strength modified polyethylene composite fiber prepared in Examples 1-3 are significantly better than those of the comparative examples, and the density is significantly lower than that of the comparative examples, indicating that the high-strength modified polyethylene composite fiber prepared by the present application can reduce the overall weight of the ship cable when applied to the ship cable, and has excellent strength and wear resistance.

[0060] In Comparative Example 1, the modified mesoporous silica microspheres in step S2 are replaced by carboxylated mesoporous silica microspheres, and the graphene cannot uniformly coat the carboxylated mesoporous silica microspheres, which are prone to agglomeration or falling off, resulting in uneven dispersion of graphene in the polyethylene composite fiber, invalidation of the lamellar strengthening effect, and a decrease in breaking strength, and the stress cannot be dispersed through the core-shell structure.

[0061] In Comparative Example 2, the carboxylated mesoporous silica microspheres are replaced by commercially available carboxylated silica microspheres, and the mesoporous structure of the mesoporous silica microspheres can prevent the inertia tension of the cable itself weight from causing the cable to break under long-term operation when the ship cable is shaken in the waves. The mesoporous silica microspheres can not only impart good mechanical properties, but also reduce the weight of the material and reduce the risk of cable breakage.

[0062] In Comparative Example 3, the functionalized graphene / mesoporous silica microspheres in step S4 are replaced by graphene / mesoporous silica microspheres prepared in step S2, and the graft modification of hydroxyethyl methacrylate introduces a hydrophobic alkane long chain, which has good compatibility with white oil, and the steric hindrance effect prevents the microspheres from approaching and aggregating, so that they are more uniformly and stably dispersed in white oil. Without modification by hydroxyethyl methacrylate, the graphene / mesoporous silica microspheres cannot be effectively dispersed in white oil, resulting in agglomeration.

[0063] Although embodiments of the present application have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and alterations can be made thereto without departing from the principles and spirit of the present application.

Claims

1. A method for preparing high-strength modified polyethylene composite fiber, characterized in that, It comprises the following steps: Step one: through the amidation reaction of the carboxyl group of the carboxylated mesoporous silica microspheres and the amino group of gamma-aminopropyl triethoxysilane, modified mesoporous silica microspheres are obtained; through the chemical bonding of the silicon hydroxyl group contained in the modified mesoporous silica microspheres and the hydroxyl group on the surface of graphene, graphene / mesoporous silica microspheres are obtained; Step two: the functionalized graphene / mesoporous silica microspheres are obtained by the chemical bonding of the edge carboxyl group of the graphene / mesoporous silica microspheres and the hydroxyl group in hydroxyethyl methacrylate under the action of a dehydrating agent and a catalyst; Step three: high-strength modified polyethylene composite fibers are obtained by spinning through a double-screw extruder with ultra-high molecular weight polyethylene resin, functionalized graphene / mesoporous silica microspheres and antioxidant 1076 as raw materials; The specific preparation steps of the modified mesoporous silica microspheres are as follows: carboxylated mesoporous silica microspheres and ethanol are added to a reaction kettle, stirred at 20-25°C and 500-600r / min for 10-20min under a nitrogen atmosphere, then N,N-diisopropylethylamine and O-benzotriazole-tetramethyl urea hexafluorophosphate are added and continue to stir for 3-5min, then gamma-aminopropyl triethoxysilane is added and continue to stir for 1-2h, filter, wash the product with ethanol and isopropyl alcohol for 2-3 times respectively, and vacuum dry at 60-80°C for 1-2h to obtain modified mesoporous silica microspheres; The amount ratio of the carboxylated mesoporous silica microspheres, ethanol, N,N-diisopropylethylamine, O-benzotriazole-tetramethyl urea hexafluorophosphate and gamma-aminopropyl triethoxysilane is 20-30g:1-2L:0.125-0.15g:0.1-0.5g:15-20mL; The specific preparation steps of the functionalized graphene / mesoporous silica microspheres are as follows: graphene / mesoporous silica microspheres, hydroxyethyl methacrylate and tetrahydrofuran are added to a reaction kettle, stirred at 20-25°C and 500r / min for 20-30min, then anhydrous magnesium sulfate as a dehydrating agent and p-toluenesulfonic acid monohydrate as a catalyst are added, continue to stir for 24-26h, filter, wash the filter cake with deionized water and anhydrous ethanol for 2-4 times respectively, and vacuum dry at 60-80°C for 1-2h to obtain functionalized graphene / mesoporous silica microspheres; The amount ratio of the graphene / mesoporous silica microspheres, hydroxyethyl methacrylate, tetrahydrofuran, anhydrous magnesium sulfate and p-toluenesulfonic acid monohydrate is 12-14g:4-5g:120-140mL:0.2-0.4g:0.3-0.5g; The high-strength modified polyethylene composite fiber is prepared by the following steps: the functionalized graphene / mesoporous silica microspheres and white oil are placed in a high-speed homogenizing mixer and mixed at 3000-3200 r / min for 30-40 min, then the ultrahigh molecular weight polyethylene resin with a molecular weight of 6 million and antioxidant 1076 are added and mixed for another 30-40 min, the product is spun through a double-screw extruder at 180-200℃ and a spinning speed of 80-120 m / min, and the as-spun fiber is allowed to stand and heat-drawn at 95-100℃ to obtain the high-strength modified polyethylene composite fiber with a diameter of 60-80 μm. The functionalized graphene / mesoporous silica microspheres, white oil, ultrahigh molecular weight polyethylene resin and antioxidant 1076 are used in a ratio of 5-6 g: 200-300 mL: 100-120 g: 2-3 g.

2. The method for preparing a high-strength modified polyethylene composite fiber according to claim 1, characterized in that, The graphene / mesoporous silica microspheres are prepared by the following steps: The modified mesoporous silica microspheres and an ethanol solution with a mass fraction of 50-55% are added to a reaction kettle and stirred at 20-25℃ and 500-600 r / min for 10-20 min, the pH value is adjusted to 3-4 with NaOH, then graphene is added and the reaction is continued for 2-3 h, the product is filtered and washed with anhydrous ethanol and deionized water for 2-3 times, and vacuum dried at 60-80℃ for 1-2 h to obtain the graphene / mesoporous silica microspheres.

3. The method for preparing a high-strength modified polyethylene composite fiber according to claim 2, characterized in that, The modified mesoporous silica microspheres, ethanol solution and graphene are used in a ratio of 15-20 g: 3-4 L: 12-15 g.

4. A high-strength modified polyethylene composite fiber, characterized by, The high-strength modified polyethylene composite fiber is prepared by the method of any one of claims 1-3.