Foaming particle material with repelling effect and slippers made of foaming particle material

Abstract

The invention discloses a foaming particle material with a repelling effect and slippers produced from the material, and belongs to the technical field of slippers, zinc oxide grows on the surfaces of hollow silicon dioxide microspheres in situ, then modification is conducted through a silane coupling agent KH570, modified zinc oxide loaded hollow microspheres are obtained, and the hollow microspheres are loaded with the modified zinc oxide. Then uniformly compounding the ultrafine wormwood powder, hydroxypropyl-beta-cyclodextrin, the modified zinc oxide loaded hollow microspheres and polyvinyl alcohol PVA-1788 through a wet granulation process to obtain composite powder, and finally carrying out melt blending on the composite powder, an ethylene-vinyl acetate copolymer matrix, stearic acid, a foaming agent and a cross-linking agent, and carrying out extrusion granulation, so as to obtain the wormwood-containing foaming agent. The foaming particle material with the repelling effect is obtained; the slippers prepared from the material have antibacterial property and mechanical stability while the thermal processing loss of active ingredients of wormwood is reduced.

Description

Technical Field

[0001] This invention belongs to the field of slipper technology, specifically relating to a foamed granular material with repellent effect and slippers made from the material. Background Technology

[0002] Currently, the foamed granule materials used in sandals with repellent effects are made from lightweight foamed polymer materials such as EVA and TPR as the base material. They are functionally modified by incorporating natural plant-derived ingredients such as artemisia powder or safe chemical repellents such as IR3535. The aim is to balance the basic properties of being lightweight, soft, and slip-resistant with the function of repelling mosquitoes. Relying on the slow release of repellent ingredients, they can form a protective layer when worn, reducing the approach and bites of mosquitoes. The foam structure also enhances cushioning comfort. Some formulas also have the function of assisting in antibacterial and improving the foot environment.

[0003] However, the volatility of natural ingredients and the easy migration of chemical agents lead to insufficient repellency. Poor compatibility between active ingredients and the matrix affects the uniformity and mechanical properties of the material. During high-temperature mixing, extrusion and foaming processes, the insect-repellent active ingredients are prone to decomposition or uneven distribution, resulting in poor processing stability. These are all problems that need to be faced in preparing foamed particles with repellency effects.

[0004] Chinese invention patent application CN114835971A discloses a high-elasticity, breathable mugwort powder foamed composite material, its preparation method, and its application. The method involves acetylation and phosphorylation of mugwort powder, followed by coating and plasticizing with diethylene glycol dibenzoate. The modified mugwort powder is then blended and kneaded with EVA, high-elasticity rubber and plastic materials, foaming agents, and processing aids, and the composite material is obtained by foaming and molding, thus achieving an effective combination of the functions of mugwort and the properties of polymer materials.

[0005] In slippers that are frequently used outdoors in summer, the composite materials prepared in the above-mentioned scheme can only solve the compatibility and dispersion problems in rubber and plastic matrices such as EVA. In order to achieve a mosquito-repelling effect by directly adding mugwort powder, it is necessary to reduce the loss of mugwort active ingredients during the hot pressing process of slipper manufacturing in order to achieve long-lasting mosquito repellency. Summary of the Invention

[0006] The purpose of this invention is to provide a foamed granular material with repellent effect and slippers made from the material. By constructing a hollow microsphere thermal barrier, a zinc oxide antibacterial core and shell, and a surface modification design, combined with wet granulation process and low-temperature mixing, the slippers made from this material have antibacterial properties and mechanical stability while reducing the loss of Artemisia argyi active ingredients during thermal processing.

[0007] The objective of this invention can be achieved through the following technical solutions:

[0008] A foamed granular material with repellent effect is prepared by the following steps:

[0009] Step 1: Zinc oxide is grown in situ on the surface of hollow silica microspheres, and then modified with silane coupling agent KH570 to obtain modified zinc oxide-supported hollow microspheres.

[0010] Step 2: Ultrafine Artemisia argyi powder, hydroxypropyl-β-cyclodextrin, modified zinc oxide-supported hollow microspheres, and polyvinyl alcohol PVA-1788 are uniformly compounded by wet granulation process to obtain composite powder.

[0011] Step 3: The composite powder is melt-blended with the ethylene-vinyl acetate copolymer matrix, stearic acid, foaming agent and crosslinking agent, and then extruded and granulated to obtain a foamed granular material with repellency effect.

[0012] Furthermore, the specific preparation steps of the modified zinc oxide-supported hollow microspheres are as follows:

[0013] Zinc oxide-supported hollow microspheres were added to a methanol-water solution and sonicated for 20-30 min. Then, silane coupling agent KH570 was added while stirring. The pH was adjusted to 4 with 1 wt% hydrochloric acid, and nitrogen gas was introduced for protection. The reaction was carried out at 90-100℃ and 600-700 rpm for 24-26 h. After cooling to room temperature, the product was collected by centrifugation and washed 4-6 times alternately with anhydrous ethanol and deionized water. The product was then vacuum dried to constant weight, ground, and passed through a 100-mesh sieve to obtain modified zinc oxide-supported hollow microspheres.

[0014] Furthermore, the ratio of zinc oxide-supported hollow microspheres, methanol aqueous solution, and silane coupling agent KH570 is 6-8g: 150-200mL: 6-8mL.

[0015] Furthermore, the specific preparation steps of zinc oxide-supported hollow microspheres are as follows:

[0016] 0.5 mmol / L zinc nitrate solution and 0.5 mmol / L sodium citrate solution were refrigerated at 4°C for 30 min for later use. Hollow silica microspheres and the refrigerated zinc nitrate solution were added to the refrigerated sodium citrate solution. The mixture was stirred at 600-800 rpm in the dark for 30-40 min, then heated to 50-60°C. 5 wt% ammonia was added dropwise to adjust the pH to 9. The mixture was stirred for 90-100 min and then vacuum filtered. The filter cake was washed 5-7 times alternately with deionized water and anhydrous ethanol and then vacuum dried to constant weight to obtain zinc oxide-supported hollow microspheres.

[0017] Furthermore, the ratio of hollow silica microspheres, refrigerated zinc nitrate solution, and refrigerated sodium citrate solution is 6-8g: 1200-1500mL: 1200-1500mL.

[0018] Furthermore, the specific preparation steps of the composite powder are as follows:

[0019] Artemisia argyi powder was ultra-finely pulverized and vacuum dried to obtain ultra-fine Artemisia argyi powder. Ultra-fine Artemisia argyi powder, hydroxypropyl-β-cyclodextrin and modified zinc oxide-supported hollow microspheres were added to a mixer and dry-mixed for 10-20 minutes to obtain a mixed powder. Polyvinyl alcohol PVA-1788 was dissolved in deionized water and stirred at 70-80℃ to prepare an adhesive solution. After cooling to room temperature, the adhesive solution was sprayed into the mixed powder. After disc granulation, the powder was sieved (transferred to a disc granulator and granulated at 300-400 rpm, passed through a 20-mesh sieve, dried to constant weight by forced air, lightly crushed by a granulator, and passed through a 100-mesh sieve) to obtain a composite powder with an average particle size of 500 μm.

[0020] Furthermore, the mass ratio of ultrafine Artemisia argyi powder, hydroxypropyl-β-cyclodextrin, and modified zinc oxide-supported hollow microspheres is 3-6:3-6:12-16.

[0021] Furthermore, the ratio of polyvinyl alcohol PVA-1788, deionized water, and mixed powder is 0.6-0.8g: 6-10mL: 9-14g.

[0022] Furthermore, the specific preparation steps of a foamed granular material with repellent effect are as follows:

[0023] Ethylene-vinyl acetate copolymer is added to a mixer and mixed at 105°C until completely melted. Composite powder is added and mixing continues for 8-10 minutes. Stearic acid, foaming agent azodicarbonamide, and crosslinking agent dicumyl peroxide (DCP) are then added and mixing continues for 5-8 minutes. The mixture is then transferred to a twin-screw extruder and extruded to granulate, resulting in a foamed granular material with repellency effect.

[0024] Furthermore, the mass ratio of ethylene-vinyl acetate copolymer, composite powder, stearic acid, foaming agent azodicarbonamide, and crosslinking agent dicumyl peroxide (DCP) is 100-120: 5-8: 2.5-4: 5-8: 0.9-1.5.

[0025] This invention also provides a slipper made from a foamed granular material with a repellent effect. The specific production steps of this slipper are as follows:

[0026] Through compression molding, the foamed granules with repellent properties are precisely weighed and poured into the slipper mold cavity. The mold is then transferred to a preheated flat vulcanizing machine at 165℃ (165-170℃ is acceptable). The mold is closed, and a pressure of 13MPa (12-15MPa is acceptable) is applied. The pressure is maintained for 90 seconds (90-120 seconds is acceptable). During the depressurization foaming process, the pressure must be rapidly reduced to 2.5MPa within 2-3 seconds. The mold opens slightly, and the material rapidly expands and foams, filling the cavity. The slippers are then removed, cooled and shaped using a foot-shaped mold, and then trimmed, inspected, and packaged to obtain slippers made from foamed granules with repellent properties.

[0027] The beneficial effects of this invention are:

[0028] 1. In terms of material structure design, this invention utilizes the hollow structure of hollow silica microspheres to effectively block heat transfer. Zinc oxide is loaded onto the surface of the microspheres to form a core-shell structure. Zinc oxide not only endows the material with antibacterial function, but its combination with the hollow carrier also increases the surface area and surface roughness, enhancing the interaction and interfacial bonding between the microspheres and the polymer matrix. This helps improve the mechanical properties of the composite material and reduce the degree of deformation. Furthermore, surface modification with silane coupling agent KH-570 introduces organic functional groups onto the surface of the zinc oxide-loaded hollow microspheres. This not only improves the compatibility with the polymer matrix but also achieves strong interfacial bonding between inorganic and organic materials through chemical bonding, thereby achieving stable composite and synergistic effects in terms of reinforcement, heat insulation, and antibacterial properties.

[0029] 2. In terms of functional composite, this invention integrates ultrafine Artemisia argyi powder, hydroxypropyl-β-cyclodextrin, and modified zinc oxide-supported hollow microspheres through wet granulation. This encapsulates the volatile active ingredients in hydroxypropyl-β-cyclodextrin and Artemisia argyi, enhancing their thermal stability and processability. This helps control release and prolong repellency. The modified zinc oxide microspheres, with their surface organic modification and supported structure, enhance interfacial compatibility with the polymer matrix and further delay the release of active ingredients. Finally, wet granulation using a polyvinyl alcohol binder uniformly agglomerates the mixed powder into well-flowing composite particles, effectively solving the problem of easy agglomeration and uneven dispersion of ultrafine powders in subsequent melt blending.

[0030] 3. In this invention, the composite powder is mixed with EVA, foaming agent, etc. at a low temperature of 105°C and then extruded and granulated. During the hot pressing process to prepare slippers, the hollow microspheres provide thermal barrier, the zinc oxide provides foaming thermal stability, and the organic functional groups of the silane layer form good entanglement and interfacial bonding with the EVA molecular chains, achieving effective thermal buffering. This significantly reduces the heat loss of the active ingredients of Artemisia argyi, which helps to achieve long-term stable preservation and controllable release of the active ingredients. This solves the problem of active ingredients being easily decomposed and deactivated at high temperatures in traditional processes. Detailed Implementation

[0031] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments in 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.

[0032] Example 1: A method for preparing a foamed granular material with repellent effect, comprising the following steps:

[0033] S1: Place 1200 mL of 0.5 mmol / L zinc nitrate solution and 1200 mL of 0.5 mmol / L sodium citrate solution in a refrigerator at 4℃ for 30 min for later use; add 6 g of hollow silica microspheres, 1200 mL of the chilled zinc nitrate solution and 1200 mL of the chilled sodium citrate solution into an Erlenmeyer flask, stir at 600 rpm in the dark for 30 min, heat to 50℃, add 5 wt% ammonia dropwise to adjust the pH to 9, continue stirring for 90 min, vacuum filter, wash the filter cake 5 times alternately with deionized water and anhydrous ethanol, and vacuum dry at 60℃ to constant weight to obtain zinc oxide-supported hollow microspheres.

[0034] By using coprecipitation and in-situ hydrothermal synthesis, zinc ion release is controlled by sodium citrate complexation. Under alkaline conditions, zinc ions gradually hydrolyze to form zinc hydroxide and then dehydrate to form zinc oxide crystals. The zinc ions grow in situ and attach to the surface of the hollow microspheres through physical adsorption on the surface of the microspheres and coordination between zinc ions and functional groups on the surface of the hollow microspheres.

[0035] S2: Add 6g of zinc oxide-supported hollow microspheres to 150mL of methanol aqueous solution, sonicate for 20min, then add 6mL of silane coupling agent KH570 while stirring, adjust the pH to 4 with 1wt% hydrochloric acid, purge with nitrogen for protection, and react at 90℃ and 600rpm for 24h. Cool to room temperature, centrifuge to collect the product, wash with anhydrous ethanol and deionized water alternately 4 times, vacuum dry at 60℃ to constant weight, grind, and pass through a 100-mesh sieve to obtain modified zinc oxide-supported hollow microspheres.

[0036] Under weakly acidic conditions, silane coupling agent KH570 hydrolyzes to generate silanol, which then undergoes a dehydration condensation reaction with the hydroxyl groups on the surface of the composite powder to form stable Si-O-Zn covalent bonds. This allows the organic functional groups of KH570 to be chemically grafted onto the powder surface, achieving surface modification.

[0037] S3: 2g of Artemisia argyi powder was ultra-finely pulverized and vacuum dried to obtain ultra-fine Artemisia argyi powder; 1.5g of ultra-fine Artemisia argyi powder, 1.5g of hydroxypropyl-β-cyclodextrin and 6g of modified zinc oxide-supported hollow microspheres were added to a mixer and dry-mixed for 10min to obtain a mixed powder; 0.6g of polyvinyl alcohol PVA-1788 was dissolved in 6mL of deionized water and stirred at 70℃ to prepare an adhesive solution. After cooling to room temperature, the adhesive solution was sprayed into 9g of mixed powder and transferred to a disc granulator for granulation at 300rpm. The granules were passed through a 20-mesh sieve and dried at 60℃ to constant weight. After being lightly crushed by a granulator and passed through a 100-mesh sieve, the composite powder was obtained.

[0038] S4: Add 100g of ethylene-vinyl acetate copolymer to a mixer and mix at 105℃ until completely melted. Add 5g of composite powder and continue mixing for 8 minutes. Then add 2.5g of stearic acid, 5g of foaming agent azodicarbonamide, and 0.9g of crosslinking agent dicumyl peroxide (DCP) and continue mixing for 5 minutes. Transfer to a twin-screw extruder and extrude to granulate to obtain a foamed granular material with repellency effect.

[0039] Example 2: A method for preparing a foamed granular material with repellent effect, comprising the following steps:

[0040] S1: Place 1350 mL of 0.5 mmol / L zinc nitrate solution and 1350 mL of 0.5 mmol / L sodium citrate solution in a refrigerator at 4℃ for 30 min for later use; add 7 g of hollow silica microspheres, 1350 mL of the chilled zinc nitrate solution and 1350 mL of the chilled sodium citrate solution into an Erlenmeyer flask, stir at 700 rpm in the dark for 35 min, heat to 55℃, add 5 wt% ammonia dropwise to adjust the pH to 9, continue stirring for 95 min, vacuum filter, wash the filter cake 6 times alternately with deionized water and anhydrous ethanol, and vacuum dry at 65℃ to constant weight to obtain zinc oxide-supported hollow microspheres.

[0041] S2: Add 7g of zinc oxide-supported hollow microspheres to 175mL of methanol aqueous solution, sonicate for 25min, then add 7mL of silane coupling agent KH570 while stirring, adjust the pH to 4 with 1wt% hydrochloric acid, purge with nitrogen for protection, and react at 95℃ and 650rpm for 25h. Cool to room temperature, centrifuge to collect the product, wash with anhydrous ethanol and deionized water alternately 5 times, vacuum dry at 65℃ to constant weight, grind, and pass through a 100-mesh sieve to obtain modified zinc oxide-supported hollow microspheres.

[0042] S3: 3g of Artemisia argyi powder was ultra-finely pulverized and vacuum dried to obtain ultra-fine Artemisia argyi powder; 2.25g of ultra-fine Artemisia argyi powder, 2.25g of hydroxypropyl-β-cyclodextrin and 7g of modified zinc oxide-supported hollow microspheres were added to a mixer and dry-mixed for 15min to obtain a mixed powder; 0.7g of polyvinyl alcohol PVA-1788 was dissolved in 8mL of deionized water and stirred at 75℃ to prepare an adhesive solution. After cooling to room temperature, the adhesive solution was sprayed into 11.5g of the mixed powder and transferred to a disc granulator for granulation at 350rpm. The granules were passed through a 20-mesh sieve and dried at 65℃ to constant weight. After being lightly crushed by a granulator and passed through a 100-mesh sieve, the composite powder was obtained.

[0043] S4: Add 110g of ethylene-vinyl acetate copolymer to a mixer and mix at 105℃ until completely melted. Add 6.5g of composite powder and continue mixing for 9 minutes. Then add 3.25g of stearic acid, 6.5g of foaming agent azodicarbonamide, and 1.2g of crosslinking agent dicumyl peroxide (DCP) and continue mixing for 6.5 minutes. Transfer to a twin-screw extruder and extrude to granulate to obtain a foamed granular material with repellency effect.

[0044] Example 3: A method for preparing a foamed granular material with repellent effect, comprising the following steps:

[0045] S1: Place 1500 mL of 0.5 mmol / L zinc nitrate solution and 1500 mL of 0.5 mmol / L sodium citrate solution in a refrigerator at 4℃ for 30 min for later use; add 8 g of hollow silica microspheres, 1500 mL of the chilled zinc nitrate solution and 1500 mL of the chilled sodium citrate solution into an Erlenmeyer flask, stir at 800 rpm in the dark for 40 min, heat to 60℃, add 5 wt% ammonia dropwise to adjust the pH to 9, continue stirring for 100 min, vacuum filter, wash the filter cake alternately with deionized water and anhydrous ethanol 7 times, and vacuum dry at 70℃ to constant weight to obtain zinc oxide-supported hollow microspheres.

[0046] S2: Add 8g of zinc oxide-supported hollow microspheres to 200mL of methanol aqueous solution, sonicate for 30min, then add 8mL of silane coupling agent KH570 while stirring, adjust the pH to 4 with 1wt% hydrochloric acid, purge with nitrogen for protection, and react at 100℃ and 700rpm for 26h. Cool to room temperature, centrifuge to collect the product, wash with anhydrous ethanol and deionized water 6 times alternately, vacuum dry at 70℃ to constant weight, grind, and pass through a 100-mesh sieve to obtain modified zinc oxide-supported hollow microspheres.

[0047] S3: 4g of Artemisia argyi powder was ultra-finely pulverized and vacuum dried to obtain ultra-fine Artemisia argyi powder; 3g of ultra-fine Artemisia argyi powder, 3g of hydroxypropyl-β-cyclodextrin and 8g of modified zinc oxide-supported hollow microspheres were added to a mixer and dry-mixed for 20min to obtain a mixed powder; 0.8g of polyvinyl alcohol PVA-1788 was dissolved in 10mL of deionized water and stirred at 80℃ to prepare an adhesive solution. After cooling to room temperature, the adhesive solution was sprayed into 14g of mixed powder and transferred to a disc granulator for granulation at 400rpm. The granules were passed through a 20-mesh sieve and dried at 70℃ to constant weight. After being lightly crushed by a granulator and passed through a 100-mesh sieve, a composite powder with an average particle size of 500μm was obtained.

[0048] S4: Add 120g of ethylene-vinyl acetate copolymer to a mixer and mix at 105℃ until completely melted. Add 8g of composite powder and continue mixing for 10min. Then add 4g of stearic acid, 8g of foaming agent azodicarbonamide, and 1.5g of crosslinking agent dicumyl peroxide (DCP). Continue mixing for 8min. Transfer to a twin-screw extruder and extrude to granulate to obtain a foamed granular material with repellency effect.

[0049] In Examples 1-3, the hollow silica microspheres were selected from Hangzhou Jiayou New Materials Co., Ltd., CAS No. 7631-86-9; the Artemisia argyi powder was selected from Fufeng Ciyuan Biotechnology Co., Ltd.; the hydroxypropyl-β-cyclopaste was selected from Hubei Xinghengye Technology Co., Ltd., CAS No. 128446-35-5; the polyvinyl alcohol PVA-1788 was selected from Xiamen Minghuiyang Chemical Co., Ltd., CAS No. 9002-89-5; the ethylene-vinyl acetate copolymer was selected from Suzhou Yitianli Plastics Co., Ltd., item number HH5110DH7W3L; the stearic acid was selected from Shanghai Xinyue Chemical Co., Ltd., CAS No. 57-11-4; the azodicarbonamide was selected from Shandong Jinghao Chemical Co., Ltd., CAS No. 123-77-3; the dicumyl peroxide DCP was selected from Shanghai Bojing Chemical Co., Ltd.; and the remaining raw materials were all commercially available products.

[0050] Comparative Example 1: The difference from Example 1 is that step S1 is omitted, and the zinc oxide-supported hollow microspheres in step S2 are replaced with commercially available hollow silica microspheres. The remaining steps remain unchanged, and a foamed granular material with repellency effect is prepared.

[0051] Comparative Example 2: The difference from Example 1 is that step S2 is omitted, and the modified zinc oxide-supported hollow microspheres in step S3 are replaced with zinc oxide-supported hollow microspheres. The remaining steps remain unchanged, and a foamed granular material with repellency effect is prepared.

[0052] Comparative Example 3: The difference from Example 1 is that the wet granulation process in step S3 is replaced with a dry mechanical blending process. Specifically, "equal amounts of ultrafine Artemisia argyi powder, hydroxypropyl-β-cyclodextrin, modified zinc oxide-supported hollow microspheres and polyvinyl alcohol PVA-1788 are mechanically stirred and mixed for 60 min, and then passed through a 100-mesh sieve to obtain a dry-mixed composite powder". The composite powder in step S4 is replaced with a dry-mixed composite powder, and the other steps remain unchanged, thus preparing a foamed granular material with a repellency effect.

[0053] Slippers made from foamed granular material with repellent properties are produced through the following steps:

[0054] Through compression molding, the foamed granules with repellent properties are precisely weighed and poured into the slipper mold cavity. The mold is then transferred to a preheated flat vulcanizing machine at 165℃ (165-170℃ is acceptable). The mold is closed, and a pressure of 13MPa (12-15MPa is acceptable) is applied. The pressure is maintained for 90 seconds (90-120 seconds is acceptable). During the depressurization foaming process, the pressure must be rapidly reduced to 2.5MPa within 2-3 seconds. The mold opens slightly, and the material rapidly expands and foams, filling the cavity. The slippers are then removed, cooled and shaped using a foot-shaped mold, and then trimmed, inspected, and packaged to obtain slippers made from foamed granules with repellent properties.

[0055] The foamed granular materials with repellent effect obtained from Examples 1-3 and Comparative Examples 1-3 were made into slippers according to the method in the application example. A piece was cut out from the slippers as a sample and the following performance tests were performed:

[0056] Repellency rate: Referring to QB T8069-2024 "Test Method for Efficacy of Non-Smearable Repellents - Triple Cylinder Method", a triple cylinder apparatus was used. The sample was placed in the middle chamber, and 50 laboratory-fed sensitive female mosquitoes were placed in each of the two end chambers. Within 2 minutes, the distribution and number of mosquitoes at both ends were recorded. The repellency rate was calculated as [(TC) / (T+C)]×100%, where T is the number of mosquitoes in the control end and C is the number of mosquitoes in the sample end. The higher the repellency rate, the better the mosquito repellent effect of the material.

[0057] Antibacterial rate: Referring to GB / T 21866-2025 "Determination of Antiviral Activity and Antibacterial Properties of Coatings", a bacterial suspension containing a quantitative amount of bacteria (such as Staphylococcus aureus and Escherichia coli) was dropped onto the surface of the sample and the sterile control sample, respectively. A thin film was covered to ensure uniform contact. After incubation for 24 hours, the surviving bacteria were washed off and counted. The antibacterial rate was calculated by [(AB) / A]×100%, where A and B are the average number of viable bacteria on the control sample and the sample, respectively. The higher the antibacterial rate, the stronger the antibacterial ability of the material surface.

[0058] Tensile strength and elongation at break: Referring to GB-T1040.2-2022 "Determination of tensile properties of plastics - Part 2: Test conditions for molded and extruded plastics", the material is prepared into a standard dumbbell-shaped specimen, clamped on a tensile testing machine, and stretched at a speed of 50 mm / min until the specimen breaks. The instrument records the tensile force and deformation throughout the process. Tensile strength is the maximum stress the specimen withstands before fracture, and elongation at break is the percentage increase in length of the specimen at fracture relative to its original length. High tensile strength indicates that the material is not easily broken, and high elongation at break indicates that the material has good ductility.

[0059] Compression set: Refer to GB / T6669-2008 "Determination of Compression Set of Flexible Foam Polymer Materials" to measure the initial thickness of the sample, then place it between two flat plates and compress it to 50% of the original thickness. Keep it at 70℃ for 22 hours, release the pressure, and allow the sample to recover for 30 minutes before measuring its final thickness. Calculate the compression set using the formula: Compression Set = [(H0-Hr) / (H0-Hs)]×100%, where H0 is the initial thickness, Hs is the thickness under compression, and Hr is the thickness after recovery. A lower compression set is better, indicating stronger rebound and recovery ability of the material after long-term compression, better resistance to collapse, and less deformation of the slipper sole.

[0060] The results are shown in Table 1:

[0061] Table 1. Performance Test Results of Slipper Samples

[0062] project Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Avoidance rate % 88.6 86.4 83.8 35.7 76.3 64.5 Antibacterial rate % 96 95 93 8.3 89.2 82.4 Tensile strength (MPa) 5.4 5.2 4.9 4.1 4.2 4.5 Elongation at break % 328 314 297 255 258 272 Compression permanent deformation rate % 18.5 17.3 16.2 25.7 24.5 23.3

[0063] As can be seen from Table 1, the foamed granular materials with repellency effect prepared in Examples 1-3 of the present invention are superior to Comparative Examples 1-3 in terms of repellency, antibacterial properties, mechanical properties and resilience durability.

[0064] In Comparative Example 1, the repellency rate, antibacterial rate, tensile strength, elongation at break, and compression set were significantly degraded. This may be because the hollow silica microspheres were not loaded with zinc oxide. Zinc oxide itself has excellent antibacterial properties and can synergistically interact with the Artemisia argyi components to jointly volatilize and repel mosquitoes. Its absence leads to a significant decrease in antibacterial and repellent functions. At the same time, the zinc oxide crystals generated in situ are loaded on the surface of the microspheres at the nanoscale, which can increase the interaction and interfacial bonding between the microspheres and the polymer matrix, and help improve the mechanical properties of the composite material and reduce compression set.

[0065] The tensile strength, elongation at break, and compression set in Comparative Example 2 showed some deterioration, which may be due to the unmodified zinc oxide-supported hollow microspheres. Grafting with silane coupling agent KH570 can introduce organic functional groups on the surface of the zinc oxide-supported hollow microspheres, improving their compatibility and interfacial bonding with the organic polymer matrix. The unmodified powder surface is highly polar and has poor dispersibility in the non-polar EVA matrix, making it prone to agglomeration. This leads to a decrease in stress transfer efficiency and becomes a defect point inside the material. Agglomerates may become structural defects during the foaming process, affecting the integrity of the cell walls and resulting in poorer resilience and increased compression set after compression.

[0066] The repellency and antibacterial rate deteriorated in Comparative Example 3, possibly because the wet granulation process was replaced with dry mechanical blending. The wet granulation process can uniformly disperse the ultrafine Artemisia argyi powder and modified zinc oxide-supported hollow microspheres. Polyvinyl alcohol PVA-1788, as a binder and dispersant, effectively encapsulates the functional powder and forms a more stable composite structure. However, dry mechanical blending is prone to uneven distribution and agglomeration of functional components (Artemisia argyi powder and modified zinc oxide-supported hollow microspheres) in the final composite material. This results in uneven release of the repellent component, Artemisia argyi volatiles, and rapid loss of active ingredients due to heat during slipper preparation, leading to a decrease in repellency rate. The effective exposed surface area of ​​the antibacterial component (zinc oxide) is reduced and unevenly distributed, affecting the antibacterial efficiency.

[0067] 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 variations can be made to these embodiments without departing from the principles and spirit of the invention.

Claims

1. A foamed granular material with a repellent effect, characterized in that, Prepared by the following steps: Step 1: Zinc oxide is grown in situ on the surface of hollow silica microspheres, and then modified with silane coupling agent KH570 to obtain modified zinc oxide-supported hollow microspheres; Step 2: Ultrafine Artemisia argyi powder, hydroxypropyl-β-cyclodextrin, modified zinc oxide supported hollow microspheres, and polyvinyl alcohol PVA-1788 are uniformly compounded by wet granulation process to obtain composite powder; Step 3: Melt-blend the composite powder with the ethylene-vinyl acetate copolymer matrix, stearic acid, foaming agent and crosslinking agent, then extrude and granulate to obtain a foamed granular material with repellency effect.

2. The foamed granular material with repellent effect according to claim 1, characterized in that, The specific preparation steps of the modified zinc oxide-supported hollow microspheres are as follows: Zinc oxide-supported hollow microspheres were added to a methanol-water solution and sonicated for 20-30 min. Silane coupling agent KH570 was added under stirring. The pH was adjusted to 4 with 1 wt% hydrochloric acid. The reaction was carried out under nitrogen protection at 90-100℃ and 600-700 rpm for 24-26 h. After cooling to room temperature, the product was collected by centrifugation, washed, dried, ground, and passed through a 100-mesh sieve to obtain modified zinc oxide-supported hollow microspheres.

3. The foamed granular material with repellent effect according to claim 2, characterized in that, The ratio of zinc oxide-supported hollow microspheres, methanol aqueous solution, and silane coupling agent KH570 is 6-8g: 150-200mL: 6-8mL.

4. The foamed granular material with repellent effect according to claim 2, characterized in that, The specific preparation steps of the zinc oxide-supported hollow microspheres are as follows: 0.5 mmol / L zinc nitrate solution and 0.5 mmol / L sodium citrate solution were refrigerated at 4°C for 30 min for later use. Hollow silica microspheres and the refrigerated zinc nitrate solution were added to the refrigerated sodium citrate solution. The mixture was stirred at 600-800 rpm in the dark for 30-40 min. Then, 5 wt% ammonia was added dropwise at 50-60°C to adjust the pH to 9. The mixture was stirred for another 90-100 min. The mixture was then vacuum filtered, and the filter cake was washed and dried to obtain zinc oxide-supported hollow microspheres.

5. A foamed granular material with a repellent effect according to claim 4, characterized in that, The ratio of the hollow silica microspheres, the chilled zinc nitrate solution, and the chilled sodium citrate solution is 6-8g: 1200-1500mL: 1200-1500mL.

6. The foamed granular material with repellent effect according to claim 1, characterized in that, The specific preparation steps of the composite powder are as follows: Ultrafine Artemisia argyi powder, hydroxypropyl-β-cyclodextrin, and modified zinc oxide-supported hollow microspheres were added to a mixer and dry-mixed for 10-20 minutes to obtain a mixed powder. Polyvinyl alcohol PVA-1788 was dissolved in deionized water and stirred at 70-80℃ to prepare an adhesive solution. The cooled adhesive solution was added to the mixed powder by spraying. After disc granulation, the powder was sieved to obtain a composite powder with an average particle size of 500 μm.

7. A foamed granular material with a repellent effect according to claim 6, characterized in that, The mass ratio of the ultrafine Artemisia argyi powder, hydroxypropyl-β-cyclodextrin, and modified zinc oxide-supported hollow microspheres is 3-6:3-6:12-16; The ratio of polyvinyl alcohol PVA-1788, deionized water, and mixed powder is 0.6-0.8g: 6-10mL: 9-14g.

8. A foamed granular material with a repellent effect according to claim 1, characterized in that, The specific preparation steps of the foamed granular material with repellent effect are as follows: Ethylene-vinyl acetate copolymer is added to a mixer and mixed at 105°C until completely melted. Composite powder is added and mixing continues for 8-10 minutes. Stearic acid, foaming agent azodicarbonamide, and crosslinking agent dicumyl peroxide (DCP) are then added and mixing continues for 5-8 minutes. The mixture is then transferred to a twin-screw extruder and extruded to granulate, resulting in a foamed granular material with repellency effect.

9. A foamed granular material with a repellent effect according to claim 8, characterized in that, The mass ratio of the ethylene-vinyl acetate copolymer, composite powder, stearic acid, foaming agent azodicarbonamide, and crosslinking agent dicumyl peroxide (DCP) is 100-120: 5-8: 2.5-4: 5-8: 0.9-1.

5.

10. A type of slipper, characterized in that, It is produced from the foamed granular material with repellent effect as described in any one of claims 1-9.