Preparation method of nano silicon dioxide modified high-density polyethylene wear-resistant plate

Abstract

The invention discloses a preparation method of a nano silicon dioxide modified high-density polyethylene wear-resistant plate, and belongs to the technical field of polyethylene plates, the method comprises the following steps: firstly preparing an antioxidant PMMA microcapsule, then preparing titanium dioxide and silicon dioxide, and modifying by KH550 to obtain modified nano titanium-silicon composite particles; then, an antioxidant coated PMMA microcapsule, the modified nano titanium-silicon composite particles, POE-g-MAH and HDPE particles are premixed, and the wear-resistant plate is obtained through twin-screw extrusion granulation and pulsating force field assisted molding; through the synergistic effect of the antioxidant coated PMMA microcapsule, the modified nano titanium-silicon composite particles and the compatilizer POE-g-MAH, the problems that the wear resistance of the HDPE plate is insufficient and the antioxidant is easily adsorbed by nano silicon dioxide to cause aging resistance attenuation are solved, and the wear resistance, thermal oxidation / light aging resistance and mechanical property improvement of the plate are realized; and the requirements of high-frequency wear scenes such as mine conveying and outdoor engineering can be met.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of polyethylene plates, and particularly relates to a preparation method of a nano-silicon dioxide modified high-density polyethylene wear-resistant plate. BACKGROUND

[0002] High-density polyethylene (HDPE) is a general-purpose thermoplastic engineering plastic with excellent comprehensive performance and low cost. Due to its high crystallinity, good chemical stability, excellent impact resistance and relatively low cost, it is widely used in packaging, construction, automobiles and pipelines. However, its insufficient wear resistance limits its application in high-frequency wear scenarios such as mine transportation and industrial drainage. To improve the mechanical and wear resistance of HDPE, conventional methods include compounding with inorganic fillers or blending with other polymers.

[0003] As an important inorganic nano-filler, nano-silicon dioxide has high specific surface area, high hardness and good reactivity, and is widely used in the modification of high polymer materials. It can play multiple roles such as reinforcement, toughening, wear resistance improvement and heat resistance improvement in the polymer matrix.

[0004] The application of HDPE wear-resistant plate in outdoor engineering fields needs to resist not only particle wear but also natural aging risk. A kind of wear-resistant and scratch-resistant ultra-high molecular polyethylene composite plate and its preparation method are disclosed in Chinese patent CN104530538A. The anti-thermal-oxidative aging performance of the material is improved by the compounding system of antioxidant 168 and antioxidant 1010. However, the above antioxidants are polar molecules of hindered phenol, which have poor compatibility with non-polar HDPE matrix. They are easy to migrate from the inside to the surface or interface in the matrix, and are also easy to volatilize and lose due to outdoor environment, or to be further adsorbed and locked by the silicon hydroxyl on the surface of nano-silicon dioxide. Under the double effects, the effective amount of antioxidant continuously decreases, and its anti-aging effect significantly decays, finally making it difficult for the material to balance wear resistance and long-term anti-aging performance in outdoor working conditions. SUMMARY

[0005] The purpose of the present application is to provide a preparation method of a nano-silicon dioxide modified high-density polyethylene wear-resistant plate. Through the synergistic effect of antioxidant@PMMA microcapsules, modified nano-titanium silicon composite particles and compatibilizer POE-g-MAH, the problems of insufficient wear resistance of HDPE plate and easy adsorption of antioxidant by nano-silicon dioxide leading to anti-aging decay are solved, and the wear resistance, anti-thermal-oxidative / light aging and mechanical property improvement of the plate are realized, which can meet the needs of high-frequency wear scenarios such as mine transportation and outdoor engineering.

[0006] The purpose of the present application can be achieved by the following technical solutions: The preparation method of the nano-silicon dioxide modified high-density polyethylene wear-resistant plate comprises the following steps: Step 1: Using suspension polymerization, methyl methacrylate is used to form an antioxidant that serves as the core material, thus obtaining antioxidant@PMMA microcapsules.

[0007] Step 2: Construct a silica shell on the surface of titanium dioxide nanoparticles to obtain titanium dioxide@silicon dioxide powder, which is then modified with KH550 to obtain modified nano-titanium-silicon composite particles.

[0008] Step 3: Premix antioxidant@PMMA microcapsules, modified nano-titanium silicon composite particles, POE-g-MAH and HDPE particles, and granulate them by twin-screw extrusion to obtain composite blend material.

[0009] Step 4: After melting the composite blend material, cut, fold, and pressurize it to cool and form a nano-silica modified high-density polyethylene wear-resistant sheet.

[0010] Furthermore, the specific preparation steps of the modified nano-titanium-silicon composite particles are as follows: Titanium dioxide@silicon dioxide powder and anhydrous ethanol were added to a reaction vessel and stirred at 28°C for 20 min. Silane coupling agent KH550, anhydrous ethanol, and deionized water were added to the stirred vessel. The pH was adjusted to 9-10 with ammonia water, and the mixture was magnetically stirred for 25 min. The mixture in the stirred vessel was then added dropwise to the reaction vessel. The reaction was carried out at 70°C under reflux for 3 h. After the reaction was completed, the mixture was repeatedly washed with anhydrous ethanol and filtered. The resulting filter cake was vacuum dried at 70°C to obtain modified nano-titanium-silicon composite particles.

[0011] Furthermore, the specific preparation steps for titanium dioxide@silicon dioxide powder are as follows: Anatase titanium dioxide and an aqueous ethanol solution were added to a reaction vessel and ultrasonically dispersed for 12-18 min. Then, polyvinylpyrrolidone was added to the vessel and magnetically stirred for 15-25 min. The pH of the system was adjusted to 9-10 with ammonia. Next, a mixed solution of tetraethyl orthosilicate and anhydrous ethanol was slowly added dropwise to the vessel and reacted at 28-32℃ for 20-28 h. After the reaction was completed, the product in the vessel was centrifuged and washed with water until the pH of the filtrate was 6.8-7.2. The obtained solid was vacuum dried at 75-85℃ for 10-14 h to obtain titanium dioxide@silicon dioxide powder.

[0012] Furthermore, the ratio of tetraethyl orthosilicate to anhydrous ethanol in the tetraethyl orthosilicate-anhydrous ethanol mixed solution is 20-30 mL: 450-550 mL.

[0013] Furthermore, the ratio of anatase titanium dioxide, polyvinylpyrrolidone, and tetraethyl orthosilicate is 2-3g: 3-5g: 20-30mL.

[0014] Furthermore, the volume fraction of the ethanol-water solution is 10%.

[0015] Furthermore, the specific preparation steps of the antioxidant@PMMA microcapsules are as follows: Sodium dodecyl sulfate and deionized water were added to a reaction vessel and stirred until dissolved. Methyl methacrylate, divinylbenzene, antioxidant, and azobisisobutyronitrile were mixed and ultrasonically dispersed for 10-20 min to obtain an oil phase. This oil phase was added to the reaction vessel and stirred at 30-40℃ and 2500-3500 r / min for 8-15 min. Then, the temperature was raised to 75-90℃ and the reaction was carried out at 500-700 r / min for 6-8 h. After the reaction was completed, the product was filtered, the precipitate was washed with ethanol 2-4 times, and dried in an oven at 45-55℃ for 20-28 h to obtain antioxidant@PMMA microcapsules.

[0016] Furthermore, the ratio of sodium dodecyl sulfate, deionized water, methyl methacrylate, divinylbenzene, antioxidant, and azobisisobutyronitrile is 0.5-1.5g: 80-120mL: 8-10g: 3-6g: 8-15g: 0.2-0.5g.

[0017] Furthermore, the antioxidant is either antioxidant 1135 or antioxidant 1315.

[0018] The beneficial effects of this invention are: 1. This invention uses cross-linked polymethyl methacrylate (PMMA) as the wall material to encapsulate antioxidant 1135 into a core-shell structure, preparing antioxidant@PMMA microcapsules. On the one hand, this avoids direct contact between the antioxidant and nano-silica, completely blocking adsorption and ensuring the antioxidant remains stable and effective within the matrix. On the other hand, after being encapsulated within the PMMA microcapsules, the antioxidant cannot directly contact the HDPE matrix, and its migration is physically blocked by the PMMA wall material, preventing it from migrating to the matrix surface / interface and volatilizing due to poor compatibility with HDPE. This allows the board to maintain excellent resistance to thermo-oxidative aging during long-term outdoor use, resolving the core contradiction of difficulty in balancing wear resistance and aging resistance. Simultaneously, the dense and highly stable structure of the PMMA wall material allows for the continuous and uniform release of the core antioxidant 1135 into the HDPE matrix through slow penetration during long-term outdoor use, preventing concentrated consumption of the antioxidant in the early stages and maintaining an effective antioxidant concentration in the matrix.

[0019] 2. In this invention, a dense silica shell is grown on the surface of anatase titanium dioxide, and then grafted and modified with silane coupling agent KH550. Silica has high hardness, titanium dioxide has a certain rigidity to assist in reinforcement, and amino groups are introduced on the surface of the particles after modification to react with subsequent compatibilizers, thereby improving the dispersibility in the HDPE matrix, significantly enhancing the wear resistance of the board while strengthening the mechanical strength and structural stability. Anatase titanium dioxide has excellent UV shielding properties, which can reduce the damage of ultraviolet rays to the molecular chain of HDPE, delay the photo-aging degradation of the board from the source, provide basic anti-aging protection for the board, and complement the anti-thermal-oxidative aging effect of antioxidant @PMMA microcapsules, achieving dual protection against photo-aging and thermal-oxidative aging. The silica outer layer isolates titanium dioxide from direct contact with the HDPE matrix, while blocking excessive excitation of titanium dioxide by ultraviolet light, effectively inhibiting its photocatalytic performance. This retains the UV shielding advantage of titanium dioxide while avoiding its catalytic damage to the matrix, ensuring stable anti-aging effects without side effects.

[0020] 3. In this invention, maleic anhydride-grafted polyolefin elastomer (POE-g-MAH) is added. Its maleic anhydride groups react with the amino groups on the surface of the modified nanoparticles. The polyolefin segments have excellent compatibility with HDPE and also have a certain affinity with the polymer structure of PMMA microcapsule wall material. This effect of being compatible with both nanoparticles and microcapsules and HDPE matrix can make the components in the premix more uniformly dispersed, further eliminating internal interface defects of the material. This not only ensures the stable performance of anti-aging and wear resistance, but also avoids the decline in local mechanical properties caused by component agglomeration, and improves the overall performance consistency of the board. Detailed Implementation

[0021] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0022] Example 1: Preparation method of nano-silica modified high-density polyethylene wear-resistant sheet

[0023] S1: Add 1g of emulsifier sodium dodecyl sulfate and 100mL of deionized water to the reactor and stir until dissolved. Mix 9g of wall material monomer methyl methacrylate (MMA), 5g of crosslinking agent divinylbenzene, 11g of core material antioxidant 1135 and 0.3g of initiator azobisisobutyronitrile and ultrasonically disperse for 15min to obtain an oil phase. Add the oil phase to the reactor and stir for 12min at 35℃ and 3000r / min. Then raise the temperature to 80℃ and react for 7h at 600r / min. After the reaction is completed, filter the product, wash the precipitate three times with ethanol, and dry it in an oven at 50℃ for 24h to obtain antioxidant @PMMA microcapsules.

[0024] An oil phase containing wall material monomer (MMA), crosslinking agent, core material antioxidant 1135, and initiator is dispersed in an aqueous phase using an emulsifier. A stable oil-in-water emulsion is formed by high-speed stirring. Subsequently, the temperature is raised to induce free radical polymerization of MMA and crosslinking agent, forming PMMA crosslinked wall material on the surface of the oil phase droplets, which encapsulates the internal antioxidant core material. Finally, antioxidant@PMMA core-shell structured microcapsules are obtained after separation and drying.

[0025] S2: 2.5g of anatase titanium dioxide and 500mL of 10% (v / v) ethanol aqueous solution were added to the reactor and ultrasonically dispersed for 16min. Then, 4g of dispersant polyvinylpyrrolidone was added to the reactor and magnetically stirred for 20min until uniformly dispersed. The pH of the system was adjusted to 10 with ammonia. Then, a mixed solution of 25mL tetraethyl orthosilicate and 500mL anhydrous ethanol was slowly added dropwise to the reactor and reacted at 30℃ for 24h. After the reaction was completed, the product in the reactor was centrifuged and washed with water until the pH of the filtrate was 7. The obtained solid was then vacuum dried at 80℃ for 12h to obtain titanium dioxide@silicon dioxide powder.

[0026] Anatase titanium dioxide has abundant hydroxyl groups on its surface. Tetraethyl orthosilicate hydrolyzes under alkaline conditions to generate silicic acid. The Si-OH on its surface undergoes a dehydration condensation reaction with the Ti-OH on the titanium dioxide surface, forming chemical bonds that anchor the silica precursor to the titanium dioxide surface. As the reaction proceeds, the Si-OH between silicic acid molecules further undergoes dehydration condensation and connects with each other through Si-O-Si bonds, gradually forming a three-dimensional network structure. Finally, a uniform and dense silica shell grows on the titanium dioxide surface.

[0027] S3: Add 9g of titanium dioxide@silicon dioxide powder and 300mL of anhydrous ethanol to the reaction vessel and stir for 20min at 28℃. Add 0.2g of silane coupling agent KH550, 150mL of anhydrous ethanol and 30mL of deionized water to the stirred vessel. Adjust the pH to 10 by adding ammonia dropwise and stir magnetically for 25min until KH550 is fully hydrolyzed. Then add the mixture in the stirred vessel dropwise to the reaction vessel and react for 3h at 70℃ and under reflux. After the reaction is complete, wash the product in the reaction vessel repeatedly with anhydrous ethanol and filter until the filtrate is clear and transparent. Dry the obtained filter cake under vacuum at 70℃ to obtain modified nano-titanium-silicon composite particles.

[0028] The ethoxy group of silane coupling agent KH550 hydrolyzes under alkaline conditions to generate highly reactive silanol groups. These silanol groups undergo dehydration condensation with the hydroxyl groups remaining on the surface of titanium dioxide@silica, thereby achieving graft modification of KH550 on the substrate surface and forming Si-O-Si covalent bonds. Furthermore, the amino groups contained in the KH550 molecule are retained and introduced onto the surface of the modified nano-titanium-silica composite particles.

[0029] S4: Add 6g of antioxidant@PMMA microcapsules, 10g of modified nano silica particles and 0.4g of maleic anhydride grafted polyolefin elastomer (POE-g-MAH) to a high-speed mixer, set the temperature to 85℃ and the speed to 1800r / min, mix for 25min to obtain a uniform premix. Add the premix and 100g of HDPE particles to a twin-screw extruder, set the extrusion temperature to 200℃ and the screw speed to 320r / min, melt blend and extrusion granulation to obtain a composite blend material.

[0030] The maleic anhydride groups of POE-g-MAH react with amino groups on the surface of modified nano-silica, while its polyolefin segments have good compatibility with HDPE, acting as an interfacial compatibilizer to initially and uniformly disperse the components.

[0031] S5: Pour the composite blend material into the mold, apply a pulsed force field with a frequency of 5Hz and an amplitude of 18MPa for 4 minutes, then heat it to 200℃ at a heating rate of 5℃ / min to melt and form a molten billet. Then, take out the billet, cut it in half, fold it, and put it back in the center of the mold. Apply a static pressure of 11MPa for 2 minutes and reheat it to 200℃. Then, apply a pressure of 8MPa to the preheated billet to the mold temperature for 2 minutes and repeat 3 times. Finally, cool the mold at a pressure of 20MPa for 18 minutes to obtain nano-silica modified high-density polyethylene wear-resistant sheet.

[0032] Example 2: Preparation method of nano-silica modified high-density polyethylene wear-resistant sheet, the difference from Example 1 is that antioxidant 1135 is replaced with antioxidant 1315 in step S1, and the other steps and parameters remain the same.

[0033] Examples 3-5: Preparation methods of nano-silica modified high-density polyethylene wear-resistant sheets. The difference from Example 1 is that the amount of substance added in step S1 is different, while the other steps and parameters remain the same. The specific amounts added are shown in Table 1 below.

[0034] Table 1. Comparison of the amount of substances used in step S1

[0035] Examples 6-8: Preparation methods of nano-silica modified high-density polyethylene wear-resistant sheets. The difference from Example 1 is that the amount of substance added in step S4 is different, while the other steps and parameters remain the same. The specific amounts added are shown in Table 2 below.

[0036] Table 2 Comparison of Substance Amounts in Step S4

[0037] Comparative Example 1: Based on Example 1, step S1, the preparation of antioxidant @PMMA microcapsules, was omitted. In step S4, an equal amount of antioxidant 1135 was added to replace the antioxidant @PMMA microcapsules. The remaining steps and parameters remained unchanged, and nano-silica modified high-density polyethylene wear-resistant sheet material was obtained.

[0038] Comparative Example 2: Based on Example 1, the preparation of titanium dioxide@silica powder in step S2 and the KH550 grafting modification in step S3 were omitted. In step S4, an equal amount of unmodified nano-silica was added to replace the modified nano-titanium-silica composite particles. The remaining steps and parameters remained unchanged, and nano-silica modified high-density polyethylene wear-resistant sheet was obtained.

[0039] Comparative Example 3: Based on Example 1, the maleic anhydride-grafted polyolefin elastomer (POE-g-MAH) in step S4 was removed, while the remaining steps and parameters remained unchanged, resulting in a nano-silica modified high-density polyethylene wear-resistant sheet.

[0040] The performance of nano-silica modified high-density polyethylene wear-resistant sheets prepared in Examples 1-8 and Comparative Examples 1-3 was tested. For wear resistance testing, the volumetric wear amount was measured according to the test method specified in GB / T3960-2016. A load of 50 N was applied to the sample, the sliding speed was 0.5 m / s, and the test time was 1 hour. The smaller the measured volumetric wear amount, the better the wear resistance. The thermo-oxidative aging resistance was tested according to GB / T7141-2008. The samples were aged in an environment of 80℃ for 1000 hours. The samples were removed at 0h, 200h, 500h, and 1000h, and the tensile properties were measured according to GB / T1040.2-2006. The light aging resistance test was conducted according to the test method of GB / T16422.2-2014, with an irradiance of 0.51 W / (m²). 2 The UV radiation was measured at 65℃, 60% relative humidity, and 1000h. The color difference ΔE after aging was used as the evaluation index. The smaller the ΔE value, the smaller the color change and the lower the degree of molecular chain degradation after UV irradiation, and the better the resistance to photoaging. The tensile properties were tested according to the test method of GB / T1040.2-2006 standard, with tensile strength and elongation at break as evaluation indexes. The higher the value, the better the mechanical load-bearing capacity and toughness of the board.

[0041] Table 3. Performance Test Results of High-Density Polyethylene Abrasion-Resistant Sheets

[0042] As can be seen from Table 3, Examples 1-8 utilize the synergistic effect of antioxidant @PMMA microcapsules, modified nano-titanium silicon composite particles, and POE-g-MAH compatibilizer. Through the microcapsules preventing antioxidant adsorption, the titanium silicon composite particles providing UV protection and wear resistance reinforcement, and the compatibilizer optimizing dispersion, the wear resistance, heat and oxygen / photoaging resistance, and mechanical properties of the sheet material are synergistically improved, meeting the needs of outdoor engineering applications. In Example 2, antioxidant 1135 in the core material was replaced with antioxidant 1315 in step S1. The test results were similar to those in Example 1, demonstrating that replacing the hindered phenolic equivalent antioxidant can improve the adaptability of process raw materials without causing a deterioration in wear resistance and anti-aging performance. In Examples 3-5, the improvement in various properties by adjusting the amount of raw materials used in the microcapsule preparation in step S1 indicates that optimizing the amount of raw materials used in S1 can enhance the encapsulation and sealing performance of the PMMA crosslinked wall material on the core material antioxidant and the slow-release effect, further strengthening the resistance to thermo-oxidative / photo-aging and improving wear resistance. In Examples 6-8, by optimizing the amount of premixed components in step S4, the uniform dispersion of each functional component in the HDPE matrix can be promoted, which can fully utilize the wear-resistant reinforcing effect of modified nanoparticles, ensure the continuous release of antioxidants, and avoid the decrease in mechanical toughness caused by uneven component dispersion, thus meeting the high requirements for comprehensive performance under complex working conditions.

[0043] Comparative Example 1 omitted step S1, the preparation of antioxidant@PMMA microcapsules, based on Example 1, and directly added an equal amount of antioxidant 1135 to replace the microcapsules. As shown in Table 3, its volumetric wear amount, tensile strength retention rate, and color difference ΔE against photoaging were significantly worse than those of Example 1. This is because the uncoated antioxidant was strongly adsorbed by the silanol groups on the surface of nano-silica, resulting in a significant reduction in the effective concentration of antioxidant in the HDPE matrix. The anti-thermal / photoaging effect was significantly weakened, and a stable antioxidant-wear-resistant synergistic system was not formed. The wear resistance deteriorated simultaneously, and it could not meet the long-term use requirements of outdoor high-frequency wear scenarios.

[0044] Comparative Example 2 omits step S2, which involves the preparation of titanium dioxide@silica powder, and step S3, which involves KH550 modification. Instead, it uses unmodified nano-silica to replace the modified nano-titanium-silica composite particles. Table 3 shows that the volumetric wear, color difference ΔE in anti-photoaging, and tensile strength are significantly deteriorated. On the one hand, the lack of UV shielding effect of anatase titanium dioxide and photocatalytic inhibition effect of the silica shell leads to a significant deterioration in the anti-photoaging performance of the board. On the other hand, the unmodified nano-silica has poor dispersibility and weak interfacial bonding with the HDPE matrix, making it impossible to form an effective wear-resistant reinforcing network, resulting in a double deterioration in wear resistance and mechanical properties.

[0045] Comparative Example 3 removed the POE-g-MAH compatibilizer in step S4 of Example 1, which caused the modified nano-titanium silicon composite particles and antioxidant @PMMA microcapsules to easily agglomerate in the HDPE matrix, forming local weak areas. This not only weakened the wear-resistant reinforcement effect of the nanoparticles, but also destroyed the mechanical structural integrity of the matrix, verifying the key role of POE-g-MAH in ensuring the uniformity of component dispersion and improving the interfacial bonding strength.

[0046] It should be noted that, in this document, terms such as “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0047] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention.

Claims

1. A method for preparing nano-silica modified high-density polyethylene wear-resistant sheet, the method comprising: The composite blend material is prepared by melting, cutting, folding, and pressing and cooling the melted material to form a composite blend. The composite blend material is characterized by the following steps: Step 1: Using suspension polymerization, methyl methacrylate is used to form an antioxidant that serves as the core material for the wall coating, resulting in antioxidant@PMMA microcapsules; Step 2: Construct a silica shell on the surface of titanium dioxide nanoparticles to obtain titanium dioxide@silicon dioxide powder, which is then modified with KH550 to obtain modified nano-titanium-silicon composite particles. Step 3: Premix antioxidant@PMMA microcapsules, modified nano-titanium silicon composite particles, POE-g-MAH and HDPE particles, and granulate them by twin-screw extrusion to obtain composite blend material.

2. The method for preparing nano-silica modified high-density polyethylene wear-resistant sheet material according to claim 1, characterized in that, The specific preparation steps of the modified nano-titanium-silicon composite particles are as follows: Titanium dioxide@silicon dioxide powder and anhydrous ethanol were added to a reaction vessel and stirred at 28°C for 20 min. Silane coupling agent KH550, anhydrous ethanol, and deionized water were added to the stirred vessel. The pH was adjusted to 9-10 with ammonia water, and the mixture was magnetically stirred for 25 min. The mixture in the stirred vessel was then added dropwise to the reaction vessel. The reaction was carried out at 70°C under reflux for 3 h. After the reaction was completed, the mixture was repeatedly washed with anhydrous ethanol and filtered. The resulting filter cake was vacuum dried at 70°C to obtain modified nano-titanium-silicon composite particles.

3. The method for preparing nano-silica modified high-density polyethylene wear-resistant sheet material according to claim 2, characterized in that, The specific preparation steps of the titanium dioxide@silicon dioxide powder are as follows: Anatase titanium dioxide and an aqueous ethanol solution were added to a reaction vessel and ultrasonically dispersed for 12-18 min. Then, polyvinylpyrrolidone was added to the vessel and magnetically stirred for 15-25 min. The pH of the system was adjusted to 9-10 with ammonia. Next, a mixed solution of tetraethyl orthosilicate and anhydrous ethanol was slowly added dropwise to the vessel and reacted at 28-32℃ for 20-28 h. After the reaction was completed, the product in the vessel was centrifuged and washed with water until the pH of the filtrate was 6.8-7.

2. The obtained solid was vacuum dried at 75-85℃ for 10-14 h to obtain titanium dioxide@silicon dioxide powder.

4. The method for preparing nano-silica modified high-density polyethylene wear-resistant sheet material according to claim 3, characterized in that, The ratio of tetraethyl orthosilicate to anhydrous ethanol in the tetraethyl orthosilicate-anhydrous ethanol mixed solution is 20-30 mL: 450-550 mL.

5. The method for preparing nano-silica modified high-density polyethylene wear-resistant sheet material according to claim 3, characterized in that, The mass ratio of anatase titanium dioxide to polyvinylpyrrolidone is 2-3g:3-5g.

6. The method for preparing nano-silica modified high-density polyethylene wear-resistant sheet material according to claim 3, characterized in that, The volume fraction of the ethanol-water solution is 10%.

7. The method for preparing nano-silica modified high-density polyethylene wear-resistant sheet material according to claim 1, characterized in that, The specific preparation steps of the antioxidant@PMMA microcapsules are as follows: Sodium dodecyl sulfate and deionized water were added to a reaction vessel and stirred until dissolved. Methyl methacrylate, divinylbenzene, antioxidant, and azobisisobutyronitrile were mixed and ultrasonically dispersed for 10-20 min to obtain an oil phase. This oil phase was added to the reaction vessel and stirred at 30-40℃ and 2500-3500 r / min for 8-15 min. Then, the temperature was raised to 75-90℃ and the reaction was carried out at 500-700 r / min for 6-8 h. After the reaction was completed, the product was filtered, the precipitate was washed with ethanol 2-4 times, and dried in an oven at 45-55℃ for 20-28 h to obtain antioxidant@PMMA microcapsules.

8. The method for preparing nano-silica modified high-density polyethylene wear-resistant sheet material according to claim 7, characterized in that, The ratio of sodium dodecyl sulfate, deionized water, methyl methacrylate, divinylbenzene, antioxidant, and azobisisobutyronitrile is 0.5-1.5g: 80-120mL: 8-10g: 3-6g: 8-15g: 0.2-0.5g.

9. The method for preparing nano-silica modified high-density polyethylene wear-resistant sheet material according to claim 7, characterized in that, The antioxidant is either antioxidant 1135 or antioxidant 1315.

10. Nano-silica modified high-density polyethylene wear-resistant sheet, characterized in that, It is prepared by the preparation method described in any one of claims 1-9.

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