Food-grade environment-friendly antibacterial plastic box and preparation method thereof

Abstract

The application discloses a food-grade environment-friendly antibacterial plastic box and a preparation method thereof, and belongs to the technical field of plastics. Through a multiple antibacterial mechanism of nickel ions, copper ions and bio-based pentanediamine amino groups, the porous structure of nickel MOF releases nickel ions in a slow-release manner, the amino group antibacterial fiber can controllably release copper ions, the metal ions kill bacteria by destroying bacterial cell membranes and inhibiting enzyme activity, the positively charged amino groups of pentanediamine kill bacteria through electrostatic adsorption, the thorn-like morphology on the surface of the amino group antibacterial fiber greatly increases the contact area of bacteria, the hollow structure avoids ion burst release, and long-acting antibacterial effect is achieved. The nickel MOF and the thorn-like copper morphology which also has an antibacterial component are coated on the surface of the carbon fiber together, and the design has a special synergistic effect. The thorn-like nanoneedle tip first pierces the bacterial cell membrane, causes irreversible damage to the cell membrane, and opens a channel for the nickel ions, copper ions and pentanediamine to enter the inside of the bacteria.

Description

Technical Field

[0001] This invention belongs to the field of plastics technology, specifically a food-grade environmentally friendly antibacterial plastic box and its preparation method. Background Technology

[0002] With the improvement of people's living standards and the enhancement of food safety awareness, the antibacterial properties of food packaging materials are receiving increasing attention. Plastic boxes, due to their advantages such as light weight, low cost, ease of processing, and good transparency, are widely used in food storage, preservation, and takeout. However, ordinary plastic boxes do not possess antibacterial properties and are prone to the growth of bacteria, mold, and other microorganisms during use. This can not only lead to food spoilage and decay but also potentially cause foodborne illnesses, threatening human health.

[0003] To address this issue, antibacterial plastics have emerged. Currently, antibacterial plastics on the market mainly achieve their antibacterial function by adding antibacterial agents to the plastic matrix. Commonly used antibacterial agents include inorganic antibacterial agents (such as silver, copper, zinc and their compounds), organic antibacterial agents (such as quaternary ammonium salts, guanidines, and phenols), and natural antibacterial agents (such as chitosan and plant extracts).

[0004] Inorganic antibacterial agents have advantages such as broad antibacterial spectrum, good heat resistance, and long shelf life, but they pose a risk of heavy metal ion migration, and the antibacterial effect of single metal ions is limited, easily leading to drug resistance. Organic antibacterial agents have fast bactericidal speed and significant effect, but they have poor heat resistance, are prone to precipitation, and have a short service life. Some organic antibacterial agents also have certain toxicity, which does not meet the safety requirements for food contact materials. Natural antibacterial agents are safe and environmentally friendly, but they have poor antibacterial effect, low heat resistance, and are easy to decompose, making it difficult to meet the needs of industrial production and long-term use.

[0005] In addition, existing antibacterial plastics have a common problem: during use, due to friction, impact, cleaning, and other reasons, the antibacterial sites on the plastic surface gradually wear away and fall off, leading to a rapid decline in antibacterial performance and a significant reduction in service life. To maintain the antibacterial effect, it is often necessary to increase the amount of antibacterial agent added, but this further increases the risk of heavy metal migration and adversely affects the mechanical and processing properties of the plastic. Summary of the Invention

[0006] The purpose of this invention is to provide a food-grade environmentally friendly antibacterial plastic box and its preparation method. Through nickel ions, copper ions and bio-based pentanediamine amino groups, multiple antibacterial mechanisms are used. The porous structure of nickel MOF slowly releases nickel ions, and the aminated antibacterial fibers controllably release copper ions. Metal ions kill bacteria by destroying bacterial cell membranes and inhibiting enzyme activity. The positively charged amino groups of pentanediamine kill bacteria through electrostatic adsorption. The spiky morphology on the surface of the aminated antibacterial fibers greatly increases the bacterial contact area, and the hollow structure avoids ion burst release, thus achieving long-lasting antibacterial effect.

[0007] The objective of this invention can be achieved through the following technical solutions: A method for preparing a food-grade, environmentally friendly, antibacterial plastic box includes the following steps: Step 1: Use dilute nitric acid liquid-phase oxidation pickling to remove slurry, oil and impurities from the carbon fiber surface. At the same time, oxygen-containing functional groups are introduced into the carbon fiber surface by etching to obtain modified carbon fiber.

[0008] Step 2: Using nickel nitrate as the metal center and 2,5-diaminoterephthalic acid as the organic ligand, under hydrothermal conditions, the metal ions and ligands undergo a coordination reaction to generate MOFs, which are then firmly loaded onto the surface of the modified carbon fibers through coordination and hydrogen bonding, thus obtaining nickel MOF modified carbon fibers.

[0009] Step 3: Using the silica microsphere hard template method, ammonia water and copper nitrate complex to form copper ammonia ions, which are uniformly adsorbed on the silica template and the surface of nickel MOF modified carbon fiber. Under hydrothermal alkaline environment, the copper-based precursor grows in a directional manner to form a spiky morphology. At the same time, ammonia water etches the internal silica to form a hollow structure, thus obtaining aminated antibacterial fiber.

[0010] Step 4: The carboxyl group of 3,3'-dithiodipropionic acid is used to undergo amidation grafting with the amino groups on the surface of aminated antibacterial fibers and bio-based pentanediamine, respectively, to obtain dynamically repaired antibacterial fibers.

[0011] Step 5: Using polypropylene, polyethylene, and acrylonitrile-butadiene copolymer as the composite matrix, maleic anhydride-grafted polypropylene as the compatibilizer, and dynamically repairing antibacterial fibers, antioxidant 1010, and benzophenone-based UV absorbers, the mixture is melt-extruded, molded, and demolded to obtain a food-grade environmentally friendly antibacterial plastic box.

[0012] Furthermore, the specific preparation steps for modified carbon fiber are as follows: Carbon fibers and a 1 mol / L nitric acid solution were added to a reaction vessel at a ratio of 50-60 g: 100-110 mL. The mixture was stirred and acid-washed at 50-60℃ and 400-500 r / min for 1-2 h. After filtration, the filter cake was washed with deionized water until the final washing solution was neutral. The mixture was then vacuum-dried at 60-70℃ for 1-2 h to obtain modified carbon fibers.

[0013] Furthermore, the specific preparation steps for nickel MOF modified carbon fibers are as follows: Nickel nitrate, modified carbon fiber, 2,5-diaminoterephthalic acid, and N,N-dimethylformamide were added to a polytetrafluoroethylene hydrothermal reactor and stirred for 12-14 hours at 130-140℃ and 500-600 r / min. After the reaction was completed, the mixture was centrifuged at 6000-7000 r / min for 8-10 minutes. The precipitate was washed 2-4 times with N,N-dimethylformamide and anhydrous ethanol, respectively, and then dried under vacuum at 60-70℃ for 1-2 hours to obtain nickel MOF modified carbon fiber.

[0014] Furthermore, the ratio of nickel nitrate, modified carbon fiber, 2,5-diaminoterephthalic acid and N,N-dimethylformamide is 10-15g:40-42g:15-20g:1100-1200mL.

[0015] Furthermore, the specific preparation steps for aminated antibacterial fibers are as follows: Silica microspheres and deionized water were mixed at a ratio of 10-12g:125-130mL to obtain a silica dispersion. Then, copper nitrate, silica dispersion, nickel MOF modified carbon fiber, deionized water, and ammonia water with a mass fraction of 20-22% were added to a polytetrafluoroethylene reactor. The mixture was ultrasonically dispersed for 50-60 minutes, heated to 130-145℃, and stirred for 24-26 hours. After filtration, the product was washed 2-4 times with deionized water and anhydrous ethanol, and vacuum dried at 60-70℃ for 1-2 hours to obtain aminated antibacterial fibers.

[0016] Furthermore, the ratio of copper nitrate, silica dispersion, nickel MOF modified carbon fiber, deionized water and ammonia is 7-9g: 121-130mL: 20-30g: 135-140mL: 15-20mL.

[0017] Furthermore, the specific preparation steps for the dynamically repairing antibacterial fiber are as follows: Bio-based pentanediamine, aminated antibacterial fiber, 3,3'-dithiodipropionic acid and sodium hydroxide were added to a reaction vessel and stirred for 40-50 min at 20-25℃ and 500-600 r / min. Then, N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide were added and stirred for another 40-50 min. Anhydrous ethanol as a water-absorbing agent was then added and the reaction was continued for 18-20 h. The mixture was then rotary evaporated to obtain dynamically repaired antibacterial fiber.

[0018] Furthermore, the ratio of bio-based pentanediamine, aminated antibacterial fiber, 3,3'-dithiodipropionic acid, sodium hydroxide, N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride, N-hydroxysuccinimide, and anhydrous ethanol is 12-14g:10-12g:2-4g:4-6g:2-4g:2-4g:90-100mL.

[0019] Furthermore, the specific preparation steps for food-grade environmentally friendly antibacterial plastic boxes are as follows: Polypropylene, polyethylene, and acrylonitrile-butadiene copolymer are added to a high-speed mixer and stirred for 5-6 minutes at 90-92℃ and 500-600 rpm. Then, maleic anhydride-grafted polypropylene is added and stirring is continued for 4-6 minutes. Next, dynamic repair antibacterial fiber, antioxidant 1010, and benzophenone-based UV absorbers are added. The mixture is heated to 105-110℃ and stirred for 10-12 minutes. The mixture is then melt-extruded, molded, and demolded to obtain a food-grade environmentally friendly antibacterial plastic box.

[0020] Furthermore, the mass ratio of polypropylene, polyethylene, acrylonitrile-butadiene copolymer, maleic anhydride-grafted polypropylene, dynamically repaired antibacterial fiber, antioxidant 1010 and benzophenone-based UV absorber is 200-220:100-120:80-90:20-30:2-4:1-2:1-2.

[0021] The beneficial effects of this invention are: 1. This invention utilizes nickel ions, copper ions, and bio-based pentanediamine amino groups to achieve multiple antibacterial mechanisms. The porous structure of the nickel MOF allows for the slow release of nickel ions, while the aminated antibacterial fibers controllably release copper ions. The metal ions kill bacteria by disrupting the bacterial cell membrane and inhibiting enzyme activity. The positively charged amino groups of the pentanediamine kill bacteria through electrostatic adsorption. The spiky morphology on the surface of the aminated antibacterial fibers significantly increases the bacterial contact area, and the hollow structure prevents ion burst release, thus achieving long-lasting antibacterial effects.

[0022] 2. This invention achieves multi-point bidirectional cross-linking through disulfide bonds containing dicarboxyl groups, constructing a reversible dynamic network that enables autonomous repair and regeneration of antibacterial sites. One end of the antibacterial fiber is grafted with an amino group, while the other end is cross-linked with bio-based pentanediamine, constructing a dense cross-linked network. The disulfide bonds possess reversible breakage-recombination characteristics. After the antibacterial sites on the surface of the plastic box are damaged due to use, friction, or impact, it can autonomously repair and regenerate, avoiding the problem of rapid decline in antibacterial ability caused by filler shedding and site failure in traditional antibacterial plastics. This significantly extends the service life, and the bio-based pentanediamine further enhances the amino antibacterial properties, making it green and environmentally friendly.

[0023] 3. In this invention, nickel MOF and spiky copper morphology, which also contains antibacterial components, are co-coated on the surface of carbon fibers. This design has a special synergistic effect. The spiky nanoneedles first pierce the bacterial cell membrane, causing irreversible damage to the cell membrane, opening channels for nickel ions, copper ions and pentanediamine to enter the bacteria, significantly reducing the effective concentration of antibacterial agents. Furthermore, nickel ions and copper ions are Lewis acid catalysts, which can significantly accelerate the dynamic exchange reaction rate of disulfide bonds and shorten the repair time. Detailed Implementation

[0024] 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.

[0025] Example 1: A method for preparing a food-grade environmentally friendly antibacterial plastic box, comprising the following steps: S1: Add 50g of carbon fiber and 100mL of 1mol / L nitric acid solution to the reactor, stir and acid wash for 1h at 50℃ and 400r / min, filter, wash the filter cake with deionized water until the last washing liquid is neutral, and vacuum dry at 60℃ for 1h to obtain modified carbon fiber.

[0026] S2: 10g nickel nitrate, 40g modified carbon fiber, 15g 2,5-diaminoterephthalic acid and 1100mL N,N-dimethylformamide were added to a polytetrafluoroethylene hydrothermal reactor and stirred at 130℃ and 500r / min for 12h. After the reaction was completed, the mixture was centrifuged at 6000r / min for 8min. The precipitate was washed twice with N,N-dimethylformamide and anhydrous ethanol, respectively, and dried under vacuum at 60℃ for 1h to obtain nickel MOF modified carbon fiber.

[0027] S3: Mix 10g of silica microspheres with 125mL of deionized water to obtain a silica dispersion. Then, add 7g of copper nitrate, 121mL of silica dispersion, 20g of nickel MOF modified carbon fiber, 135mL of deionized water and 15mL of 20% ammonia water to a polytetrafluoroethylene reactor. Sonicate the mixture for 50min, heat it to 130℃ and continue stirring for 24h. Filter the mixture and wash the product twice with deionized water and anhydrous ethanol, respectively. Dry it under vacuum at 60℃ for 1h to obtain aminated antibacterial fiber.

[0028] S4: Add 12g of bio-based pentanediamine, 10g of aminated antibacterial fiber, 2g of 3,3'-dithiodipropionic acid and 4g of sodium hydroxide to a reaction vessel, and stir for 40min at 20℃ and 500r / min. Then add 2g of N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride and 2g of N-hydroxysuccinimide, and continue stirring for 40min. Then add 90mL of anhydrous ethanol as a water absorbent, and continue stirring and reacting for 18h. The mixture is then rotary evaporated to obtain dynamically repaired antibacterial fiber.

[0029] S5: Add 200g of polypropylene, 100g of polyethylene and 80g of acrylonitrile-butadiene copolymer to a high-speed mixer and stir for 5 minutes at 90℃ and 500r / min. Then add 20g of maleic anhydride-grafted polypropylene and continue stirring for 4 minutes. Next, add 2g of dynamic repair antibacterial fiber, 1g of antioxidant 1010 and 1g of benzophenone-based UV absorber. Heat to 105℃ and continue stirring for 10 minutes. Melt extrusion, molding and demolding are performed to obtain a food-grade environmentally friendly antibacterial plastic box.

[0030] Example 2: A method for preparing a food-grade environmentally friendly antibacterial plastic box, comprising the following steps: S1: Add 55g of carbon fiber and 105mL of 1mol / L nitric acid solution to the reactor, stir and acid wash for 1.5h at 55℃ and 450r / min, filter, wash the filter cake with deionized water until the last washing liquid is neutral, and vacuum dry at 65℃ for 1.5h to obtain modified carbon fiber.

[0031] S2: 12.5g nickel nitrate, 41g modified carbon fiber, 17.5g 2,5-diaminoterephthalic acid and 1150mL N,N-dimethylformamide were added to a polytetrafluoroethylene hydrothermal reactor and stirred at 135℃ and 550r / min for 13h. After the reaction was completed, the mixture was centrifuged at 6500r / min for 9min. The precipitate was washed three times with N,N-dimethylformamide and anhydrous ethanol, respectively, and dried under vacuum at 65℃ for 1.5h to obtain nickel MOF modified carbon fiber.

[0032] S3: 11g of silica microspheres and 127.5mL of deionized water were stirred and mixed to obtain a silica dispersion. Then, 8g of copper nitrate, 125.5mL of silica dispersion, 25g of nickel MOF modified carbon fiber, 137.5mL of deionized water and 17.5mL of 21% ammonia water were added to a polytetrafluoroethylene reactor. The mixture was ultrasonically dispersed for 55min, heated to 137.5℃ and stirred for 25h. After filtration, the product was washed three times with deionized water and anhydrous ethanol, respectively, and dried under vacuum at 65℃ for 1.5h to obtain aminated antibacterial fiber.

[0033] S4: Add 13g of bio-based pentanediamine, 11g of aminated antibacterial fiber, 3g of 3,3'-dithiodipropionic acid and 5g of sodium hydroxide to a reaction vessel and stir for 45min at 22.5℃ and 550r / min. Then add 3g of N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride and 3g of N-hydroxysuccinimide and continue stirring for 45min. Then add 95mL of anhydrous ethanol as a water absorbent and continue stirring for 19h. The mixture is then rotary evaporated to obtain dynamically repaired antibacterial fiber.

[0034] S5: Add 210g of polypropylene, 110g of polyethylene and 85g of acrylonitrile-butadiene copolymer to a high-speed mixer and stir for 5.5min at 91℃ and 550r / min. Then add 25g of maleic anhydride-grafted polypropylene and continue stirring for 5min. Then add 3g of dynamic repair antibacterial fiber, 1.5g of antioxidant 1010 and 1.5g of benzophenone-based UV absorber. Heat to 107.5℃ and continue stirring for 11min. Melt extrusion, molding and demolding are performed to obtain a food-grade environmentally friendly antibacterial plastic box.

[0035] Example 3: A method for preparing a food-grade environmentally friendly antibacterial plastic box, comprising the following steps: S1: Add 60g of carbon fiber and 110mL of 1mol / L nitric acid solution to the reactor, stir and acid wash for 2h at 60℃ and 500r / min, filter, wash the filter cake with deionized water until the last washing liquid is neutral, and vacuum dry at 70℃ for 2h to obtain modified carbon fiber.

[0036] S2: 15g nickel nitrate, 42g modified carbon fiber, 20g 2,5-diaminoterephthalic acid and 1200mL N,N-dimethylformamide were added to a polytetrafluoroethylene hydrothermal reactor and stirred at 140℃ and 600r / min for 14h. After the reaction was completed, the mixture was centrifuged at 7000r / min for 10min. The precipitate was washed 4 times with N,N-dimethylformamide and anhydrous ethanol, respectively, and dried under vacuum at 70℃ for 2h to obtain nickel MOF modified carbon fiber.

[0037] S3: 12g of silica microspheres and 130mL of deionized water were stirred and mixed to obtain a silica dispersion. Then, 9g of copper nitrate, 130mL of silica dispersion, 30g of nickel MOF modified carbon fiber, 140mL of deionized water and 20mL of 22% ammonia water were added to a polytetrafluoroethylene reactor. The mixture was ultrasonically dispersed for 60min, heated to 145℃ and stirred for 26h. After filtration, the product was washed 4 times with deionized water and anhydrous ethanol, respectively, and dried under vacuum at 70℃ for 2h to obtain aminated antibacterial fiber.

[0038] S4: Add 14g of bio-based pentanediamine, 12g of aminated antibacterial fiber, 4g of 3,3'-dithiodipropionic acid and 6g of sodium hydroxide to a reaction vessel, and stir for 50min at 25℃ and 600r / min. Then add 4g of N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride and 4g of N-hydroxysuccinimide, and continue stirring for 50min. Then add 100mL of anhydrous ethanol as a water absorbent, and continue stirring and reacting for 20h. The mixture is then rotary evaporated to obtain dynamically repaired antibacterial fiber.

[0039] S5: Add 220g of polypropylene, 120g of polyethylene and 90g of acrylonitrile-butadiene copolymer to a high-speed mixer and stir for 6 minutes at 92℃ and 600r / min. Then add 30g of maleic anhydride-grafted polypropylene and continue stirring for 6 minutes. Next, add 4g of dynamic repair antibacterial fiber, 2g of antioxidant 1010 and 2g of benzophenone-based UV absorber. Heat to 110℃ and continue stirring for 12 minutes. Melt extrusion, molding and demolding are then performed to obtain a food-grade environmentally friendly antibacterial plastic box.

[0040] Comparative Example 1: Based on Example 3, the dynamic repair antibacterial fiber in step S5 was replaced with the aminated antibacterial fiber prepared in step S3.

[0041] Comparative Example 2: Based on Example 3, the nickel MOF modified carbon fiber in step S3 was replaced with the modified carbon fiber prepared in step S1.

[0042] Comparative Example 3: Based on Example 3, the aminated antibacterial fiber in step S4 was replaced with the nickel MOF modified carbon fiber prepared in step S2.

[0043] Performance tests were conducted on Examples 1-3 and Comparative Examples 1-3. The antibacterial effects of the samples against Staphylococcus aureus and Escherichia coli were tested according to QB / T 2591-2003. Samples were prepared into discs with a diameter of 1 cm and a thickness of 1 mm, sterilized, and dried. A 0.2% solution of Escherichia coli and a 2% solution of Staphylococcus aureus were prepared using physiological saline solution. The pH was adjusted to 7.2 after sterilization using 0.1 mol / L sodium hydroxide solution. Sterilization was carried out at 121℃ for 30 min, followed by a 6×10⁻⁶... 5 A concentration of CFU / mL was added dropwise to the sample. A sterilized polyethylene covering film (40mm × 40mm, 0.05mm thick) was then placed over the sample and incubated at 37℃ and relative humidity greater than 90% for 24 hours. After incubation, the sample was inoculated onto agar medium (purchased from Nantong Kaiheng Biotechnology Development Co., Ltd.) at an inoculation density of 10... 5CFU was cultured at 37℃ for 24 hours, and the viable count was determined according to GB / T 4789.2. The samples were then continuously immersed in distilled water at 50℃ for 16 hours, and the antibacterial rates before and after immersion were compared to reflect the antibacterial level. The load-bearing strength of the samples was determined according to GB / T14484-2008, the tensile properties were determined according to GB / T1040.1-2018, and the tensile strength was tested according to GB / T 1040.2-2022. Tensile strength was further tested until microcracks appeared, and the food-grade environmentally friendly antibacterial plastic box was left to stand at room temperature for 24 hours. The tensile strength was tested again, and the repair rate was calculated as: Repair rate = (Tensile strength after repair / Initial tensile strength) × 100%. The results are shown in Table 1: Table 1

[0044] As shown in Table 1, Comparative Example 1 lacks a reversible disulfide network. The surface antibacterial sites cannot be regenerated after friction, impact, and cleaning wear. It lacks the large number of long-chain amino antibacterial sites provided by bio-based pentanediamine, loses the dual synergy of metal ions and organic amines, and lacks an outer dense cross-linked network. The release rate of copper and nickel ions is accelerated, and the migration of heavy metals increases significantly. The amino groups in the dynamic network cannot form chemical bonds with the maleic anhydride-grafted polypropylene in the matrix. The filler and the matrix are only physically bonded, resulting in a decrease in mechanical properties.

[0045] In Comparative Example 2, the lack of nickel ion antibacterial components resulted in the loss of the bimetallic ion synergistic effect, a decrease in the initial antibacterial rate, the disappearance of the anchoring effect of nickel MOF, easy aggregation and detachment of spiky copper-based microspheres, uncontrolled release of copper ions, loss of the porous toughening effect of nickel MOF, and the formation of a large number of stress concentration points by aggregated copper microspheres. The lack of nickel ions as Lewis acid catalysts slowed down the dynamic exchange rate of disulfide bonds, reduced self-repair efficiency, and prolonged repair time.

[0046] Comparative Example 3 lacks copper ions, a core antibacterial component, and loses the physical puncture and bactericidal effect of the spiky nanoneedles. The synergistic effect is completely lost. Without the ion-releasing structure of copper-based hollow microspheres, it relies solely on the slow release of nickel ions by nickel MOF, resulting in a decrease in antibacterial rate. The lack of the reinforcing effect of copper-based microspheres leads to a decrease in mechanical properties. However, due to the retention of the porous toughening effect of nickel MOF, stress concentration caused by filler agglomeration is avoided. Therefore, the mechanical properties are still better than those of Comparative Example 2. The spiky morphology disappears, and the bacterial contact area is reduced.

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

Claims

1. A method for preparing a food-grade, environmentally friendly, antibacterial plastic box, characterized in that, Includes the following steps: Step 1: Use dilute nitric acid liquid-phase oxidation pickling to remove slurry, oil and impurities from the carbon fiber surface. At the same time, etch oxygen-containing functional groups into the carbon fiber surface to obtain modified carbon fiber. Step 2: Using nickel nitrate as the metal center and 2,5-diaminoterephthalic acid as the organic ligand, under hydrothermal conditions, the metal ions and ligands undergo a coordination reaction to generate MOFs, which are then firmly loaded onto the surface of the modified carbon fibers through coordination and hydrogen bonding with the oxygen-containing functional groups on the carbon fiber surface, thus obtaining nickel MOF modified carbon fibers. Step 3: Using the silica microsphere hard template method, ammonia water and copper nitrate complex to form copper ammonia ions, which are uniformly adsorbed on the silica template and the surface of nickel MOF modified carbon fiber. Under hydrothermal alkaline environment, the copper-based precursor grows in a directional manner to form a spiky morphology. At the same time, ammonia water etches the internal silica to form a hollow structure, thus obtaining aminated antibacterial fiber. Step 4: The carboxyl group of 3,3'-dithiodipropionic acid is used to undergo amidation grafting with the amino groups on the surface of aminated antibacterial fibers and bio-based pentanediamine, respectively, to obtain dynamically repaired antibacterial fibers. Step 5: Using polypropylene, polyethylene, and acrylonitrile-butadiene copolymer as the composite matrix, maleic anhydride-grafted polypropylene as the compatibilizer, and dynamically repairing antibacterial fibers, antioxidant 1010, and benzophenone-based UV absorbers, the mixture is melt-extruded, molded, and demolded to obtain a food-grade environmentally friendly antibacterial plastic box.

2. The method for preparing a food-grade environmentally friendly antibacterial plastic box according to claim 1, characterized in that, The specific preparation steps for the modified carbon fiber are as follows: Carbon fibers and a 1 mol / L nitric acid solution were added to a reaction vessel at a ratio of 50-60 g: 100-110 mL. The mixture was stirred and acid-washed at 50-60℃ and 400-500 r / min for 1-2 h. After filtration, the filter cake was washed with deionized water until the final washing solution was neutral. The mixture was then vacuum-dried at 60-70℃ for 1-2 h to obtain modified carbon fibers.

3. The method for preparing a food-grade environmentally friendly antibacterial plastic box according to claim 1, characterized in that, The specific preparation steps for the nickel MOF modified carbon fiber are as follows: Nickel nitrate, modified carbon fiber, 2,5-diaminoterephthalic acid, and N,N-dimethylformamide were added to a polytetrafluoroethylene hydrothermal reactor and stirred for 12-14 hours at 130-140℃ and 500-600 r / min. After the reaction was completed, the mixture was centrifuged at 6000-7000 r / min for 8-10 minutes. The precipitate was washed 2-4 times with N,N-dimethylformamide and anhydrous ethanol, respectively, and then dried under vacuum at 60-70℃ for 1-2 hours to obtain nickel MOF modified carbon fiber.

4. The method for preparing a food-grade environmentally friendly antibacterial plastic box according to claim 3, characterized in that, The ratio of nickel nitrate, modified carbon fiber, 2,5-diaminoterephthalic acid and N,N-dimethylformamide is 10-15g:40-42g:15-20g:1100-1200mL.

5. The method for preparing a food-grade environmentally friendly antibacterial plastic box according to claim 1, characterized in that, The specific preparation steps of the aminated antibacterial fiber are as follows: Silica microspheres and deionized water were mixed at a ratio of 10-12g:125-130mL to obtain a silica dispersion. Then, copper nitrate, silica dispersion, nickel MOF modified carbon fiber, deionized water, and ammonia water with a mass fraction of 20-22% were added to a polytetrafluoroethylene reactor. The mixture was ultrasonically dispersed for 50-60 minutes, heated to 130-145℃, and stirred for 24-26 hours. After filtration, the product was washed 2-4 times with deionized water and anhydrous ethanol, and vacuum dried at 60-70℃ for 1-2 hours to obtain aminated antibacterial fibers. The ratio of copper nitrate, silica dispersion, nickel MOF modified carbon fiber, deionized water and ammonia is 7-9g: 121-130mL: 20-30g: 135-140mL: 15-20mL.

6. The method for preparing a food-grade environmentally friendly antibacterial plastic box according to claim 1, characterized in that, The specific preparation steps of the dynamically repairing antibacterial fiber are as follows: Bio-based pentanediamine, aminated antibacterial fiber, 3,3'-dithiodipropionic acid and sodium hydroxide were added to a reaction vessel and stirred for 40-50 min at 20-25℃ and 500-600 r / min. Then, N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide were added and stirred for another 40-50 min. Anhydrous ethanol as a water-absorbing agent was then added and the reaction was continued for 18-20 h. The mixture was then rotary evaporated to obtain dynamically repaired antibacterial fiber.

7. The method for preparing a food-grade environmentally friendly antibacterial plastic box according to claim 6, characterized in that, The ratio of the bio-based pentanediamine, aminated antibacterial fiber, 3,3'-dithiodipropionic acid, sodium hydroxide, N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride, N-hydroxysuccinimide, and anhydrous ethanol is 12-14g:10-12g:2-4g:4-6g:2-4g:2-4g:90-100mL.

8. The method for preparing a food-grade environmentally friendly antibacterial plastic box according to claim 1, characterized in that, The specific preparation steps for the food-grade environmentally friendly antibacterial plastic box are as follows: Polypropylene, polyethylene, and acrylonitrile-butadiene copolymer are added to a high-speed mixer and stirred for 5-6 minutes at 90-92℃ and 500-600 rpm. Then, maleic anhydride-grafted polypropylene is added and stirring is continued for 4-6 minutes. Next, dynamic repair antibacterial fiber, antioxidant 1010, and benzophenone-based UV absorbers are added. The mixture is heated to 105-110℃ and stirred for 10-12 minutes. The mixture is then melt-extruded, molded, and demolded to obtain a food-grade environmentally friendly antibacterial plastic box.

9. The method for preparing a food-grade environmentally friendly antibacterial plastic box according to claim 8, characterized in that, The mass ratio of the polypropylene, polyethylene, acrylonitrile-butadiene copolymer, maleic anhydride-grafted polypropylene, dynamically repaired antibacterial fiber, antioxidant 1010, and benzophenone-based UV absorber is 200-220:100-120:80-90:20-30:2-4:1-2:1-2.

10. A food-grade, environmentally friendly, antibacterial plastic box, characterized in that, It is prepared by the preparation method described in any one of claims 1-9.

Images