Food-grade antibacterial acrylic resin packaging material and preparation method thereof

Abstract

The invention belongs to the field of functional packaging materials, and discloses a food-grade antibacterial acrylic resin packaging material and a preparation method thereof.The food-grade antibacterial acrylic resin packaging material is based on a water-based emulsion free of volatile organic compounds, a stable dispersion system is constructed through a co-emulsion and a wetting agent, and the functional packaging material is prepared. A natural catechin polymer subjected to acrylation modification is covalently anchored to an acrylic matrix, and a natural vitamin E derivative and a metal oxide nanosheet are compounded, so that multiple functions of antibiosis, antioxidation and gas barrier are integrated. The preparation method combines emulsion polymerization with an ultraviolet light and microwave dual-curing technology, and is mild and efficient in process and free of harmful emission. The obtained coating has lasting antibacterial property, stable antioxidant property and excellent barrier property, meets the food contact safety standard, is suitable for various food packaging scenes, and has remarkable application value and industrialization prospect.

Description

Technical Field

[0001] This invention belongs to the field of functional packaging materials, specifically relating to a food-grade antibacterial acrylic resin packaging material and its preparation method. Background Technology

[0002] With increasingly stringent food safety and environmental regulations, the demand for functional packaging materials from consumers and manufacturers is growing rapidly. Traditional food packaging often uses physically mixed antimicrobial agents or single-function composite materials, which not only suffer from problems such as easy attenuation of antimicrobial activity and poor control of migration and release, but also offer limited antioxidant and gas barrier properties, making it difficult to meet the requirements of long-term preservation and sustainable development. Furthermore, common organic solvent systems and high-temperature curing processes easily generate volatile organic compound (VOC) emissions and high energy consumption during production, increasing environmental pollution and health risks. In recent years, aqueous emulsion systems have gradually become a research hotspot due to their advantages of low VOC, easy cleaning, and safe operation; however, emulsion systems still face challenges in achieving multifunctional integration in terms of stability, initial viscosity, and curing efficiency. Meanwhile, natural polyphenolic compounds (such as catechins) and natural antioxidants (such as vitamin E derivatives) have been widely studied due to their good biocompatibility and safety, but most are physically mixed, making desorption and migration control difficult. Metal oxide nanosheets (such as osmium tetroxide nanosheets) have excellent gas barrier performance, but their dispersibility and synergistic effects in polymer matrices urgently need optimization. Therefore, there is an urgent need for a comprehensive packaging material that can achieve long-lasting antibacterial, stable antioxidant, and efficient gas barrier functions, while also taking into account low VOC emissions and efficient curing production processes, so as to comprehensively improve the safety and preservation performance of food packaging. Summary of the Invention

[0003] To address the shortcomings mentioned in the background art, the present invention aims to provide a food-grade antibacterial acrylic resin packaging material and its preparation method. This material is produced by covalently bonding chemically grafted modified catechin polymers to an acrylic matrix and compounding them with natural vitamin E derivatives and osmium tetroxide nanosheets, thereby achieving a triple integration of antibacterial, antioxidant, and highly efficient gas barrier functions.

[0004] The objective of this invention can be achieved through the following technical solutions: A food-grade antibacterial acrylic resin packaging material comprises the following raw materials in parts by weight: 80-120 parts methyl acrylate, 15-25 parts hydroxyethyl acrylate, 0.5-2 parts modified catechin polymer, 0.3-0.7 parts natural vitamin E derivative, 0.1-0.3 parts osmium tetroxide nanosheets, 0.5-1.5 parts emulsifier, 0.1-0.5 parts wetting agent, and 0.2-0.6 parts photoinitiator.

[0005] More preferably, the preparation method of the modified catechin polymer specifically includes the following steps: S101. Dissolve catechin, propylene glycol dimethacrylate and azobisisobutyronitrile in tetrahydrofuran, disperse by ultrasonication and then transfer to a reaction vessel; S102. Purge nitrogen gas to replace the air in the reactor, and stir under an inert atmosphere, raising the temperature and stirring the reaction. S103. After the reaction is complete, cool to room temperature, pour the reaction solution into pre-cooled ethanol to precipitate, collect the precipitate after standing, remove impurities by washing, and place the collected solid in a vacuum drying oven to dry to constant weight to obtain the modified catechin polymer.

[0006] More preferably, the natural vitamin E derivative F is α-tocolate, the emulsifier D is polyvinyl alcohol modified acrylate, the wetting agent is a polycarboxylate complexing agent, and the photoinitiator is 2-hydroxy-2-methyl-1-phenylpropanone.

[0007] More preferably, the preparation method of osmium tetroxide nanosheets specifically includes the following steps: S201. Osmium tetroxide octahydrate and ammonium nitrate are dissolved in ethylene glycol, ultrasonically dispersed, and then a small amount of sodium dodecylbenzenesulfonate is added as a surface stabilizer. S202. Transfer the dispersion to a high-pressure reactor with a polytetrafluoroethylene liner, add an equal volume of deionized water and seal the reactor for a high-temperature hydrothermal reaction. S203. Cool to room temperature, centrifuge the reaction product to separate the solid, wash the precipitate alternately with deionized water and ethanol, place the washed precipitate in a vacuum drying oven, dry to constant weight and collect to obtain the osmium tetroxide nanosheets.

[0008] A method for preparing a food-grade antibacterial acrylic resin packaging material includes the following steps: S1. Emulsion preparation: Deionized water, methyl acrylate, hydroxyethyl acrylate, emulsifier, wetting agent and photoinitiator are put into a mixing tank, stirred and surfactant is added until a homogeneous emulsion is formed. S2. Grafting polymerization: Add the modified catechin polymer to the emulsion obtained in step S1 in batches, maintain stirring, and carry out emulsion polymerization grafting under an inert atmosphere. S3, Composite Addition: Vitamin E derivative and osmium tetroxide nanosheets are added sequentially to the polymer grafting mixture and stirred to achieve uniform dispersion; S4. Double curing: The obtained mixture is coated onto the substrate, first cured by ultraviolet light, then placed in a microwave cavity for microwave curing, and dried to obtain the food-grade antibacterial acrylic resin packaging material.

[0009] More preferably, the surfactant in step S1 is sodium dodecylbenzenesulfonate.

[0010] More preferably, the microwave curing frequency is 2.45 GHz and the power is 0.5 kW.

[0011] More preferably, the material forms a micro-nano network structure in the coating by covalently grafting modified catechin polymers to achieve continuous release of antibacterial activity.

[0012] More preferably, the coating can retain its functional properties for no less than 12 months under standard environmental conditions.

[0013] The beneficial effects of this invention are: The food-grade antibacterial acrylic resin packaging material and its preparation method provided by this invention achieve deep integration of antibacterial active ingredients and polymer networks by chemically grafting modified catechin polymers onto an acrylic matrix. This effectively avoids the problems of easy desorption and uncontrolled migration of antibacterial agents in traditional physical mixing methods. Simultaneously, the composite network formed synergistically by natural vitamin E derivatives and osmium tetroxide nanosheets in the matrix not only improves the free radical scavenging ability of the coating, giving the packaging material stable antioxidant properties, but also significantly enhances the barrier properties against oxygen and water vapor small molecules through the disordered lattice channels formed by the nanosheets in the polymer matrix. This achieves an organic integration of antibacterial, antioxidant, and highly efficient barrier functions. The preparation process uses a zero-VOC aqueous emulsion system combined with UV / microwave dual curing technology, which not only significantly shortens curing time, reduces energy consumption and process costs, but also eliminates the potential hazards of organic solvent volatilization to the environment and operator health. Furthermore, the material of this invention, while maintaining high-efficiency functionality, meets food contact safety standards, possesses excellent mechanical strength and durability, and can adapt to various packaging forms and process requirements. Attached Figure Description

[0014] The invention will now be further described with reference to the accompanying drawings.

[0015] Figure 1 The bar chart shows the comparison of the antibacterial rates of the sample materials from Examples 1-3 and Comparative Examples 1-2. Figure 2 The bar chart shows the air permeability comparison of the sample materials from Examples 1-3 and Comparative Examples 1-2; Figure 3 The graphs show the changes in the antibacterial rate of the samples from Examples 1-3 and Comparative Examples 1-2 over 0-1000 h. Detailed Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] Example 1 I. Preparation of Modified Catechin Polymers Weigh 10 g of catechin, 5 g of propylene glycol dimethacrylate, and 0.5 g of azobisisobutyronitrile (AIBN), add them to 50 mL of tetrahydrofuran, and sonicate for 10 min to fully dissolve and disperse. Transfer the mixture to a 200 mL stainless steel reactor, purge with nitrogen for 30 min, and stir at 300 rpm. Heat to 80 °C and maintain stirring under nitrogen protection for 6 h. After the reaction is complete, quickly pour the reaction solution into 250 mL of pre-cooled ethanol to precipitate the modified polymer. Let it stand for 2 h, collect the precipitate in a centrifuge tube, centrifuge at 5000 rpm for 10 min, discard the supernatant, and wash three times alternately with deionized water and ethanol. Place the washed precipitate in a vacuum drying oven and dry at 60 °C and -0.08 MPa for 12 h. Grind the dried product and pass it through a 200-mesh sieve to obtain the modified catechin polymer.

[0018] II. Preparation of Osmium Tetraoxide Nanosheets Weigh 1.0 g of osmium tetroxide octahydrate and 0.2 g of ammonium nitrate, add them to 30 mL of ethylene glycol, and disperse using ultrasound for 10 min. Add 0.1 g of sodium dodecylbenzenesulfonate and continue ultrasonic dispersion for 5 min. Transfer the mixture to a 100 mL high-pressure reactor with a polytetrafluoroethylene liner, add an equal volume of deionized water, seal the reactor, and then place the reactor in an oven at 200 ℃ for 12 h. After the reaction, cool to room temperature, slowly open the reactor to release the pressure, remove the reaction solution, and centrifuge at 8000 rpm for 15 min. Discard the supernatant, add 50 mL of deionized water to the precipitate and gently shake, then centrifuge at 8000 rpm for 10 min again. Discard the supernatant, repeat the washing process once more, wash the precipitate with 30 mL of ethanol, and centrifuge at 8000 rpm for 10 min. Collect the final precipitate and place it in a vacuum drying oven at 80 ℃ and -0.08 °C. The product was dried at MPa for 8 hours, then ground and passed through a 200-mesh sieve to obtain the osmium tetroxide nanosheets.

[0019] III. Preparation of Food-Grade Antibacterial Acrylic Resin Packaging Materials The food-grade antibacterial acrylic resin packaging material comprises the following raw materials in parts by weight: 80 parts methyl acrylate, 15 parts hydroxyethyl acrylate, 0.5 parts modified catechin polymer, 0.3 parts natural vitamin E derivative, 0.1 parts osmium tetroxide nanosheets, 0.5 parts emulsifier, 0.1 parts wetting agent, and 0.2 parts photoinitiator.

[0020] The preparation steps are as follows: 100 mL of deionized water was placed in a 250 mL stainless steel reaction vessel, and 1 g of sodium dodecylbenzenesulfonate and 0.5 g of polyvinyl alcohol-modified acrylate were added. The mixture was stirred at 300 rpm for 5 min. 80 g of methyl acrylate and 15 g of hydroxyethyl acrylate were slowly added dropwise, along with 0.2 g of photoinitiator. The mixture was stirred continuously for 20 min to obtain a homogeneous emulsion. Nitrogen gas was purged into the reaction vessel for 30 min to remove air. 0.5 g of modified catechin polymer was added to the emulsion in three batches, while stirring at 300 rpm. The temperature was raised to 70 °C, and the reaction was carried out under an inert atmosphere for 4 h. After the reaction was completed, the mixture was cooled to 40 °C, and 0.3 g of α-tocopheryl ester was added. The mixture was stirred for 5 min, and then 0.1 g of osmium tetroxide nanosheets pre-dispersed in deionized water were added. The mixture was stirred at a low speed of 200 rpm for 15 min to ensure uniform dispersion. The obtained mixture was coated onto a stainless steel plate with a coating knife, and the coating thickness was about 20 μm. It was then cured by UV irradiation at a wavelength of 365 nm and an energy density of 5 J / cm² for 30 s. The sample was then placed in a microwave cavity at 2.45 GHz and 0.5 kW for another 30 s and then microwave cured. The cured coating was then dried in an oven at 80 ℃ for 2 h to obtain the food-grade antibacterial acrylic resin packaging material.

[0021] Example 2 The preparation methods for the modified catechin polymer and osmium tetroxide nanosheets are the same as in Example 1.

[0022] The preparation process of food-grade antibacterial acrylic resin packaging material is as follows: The food-grade antibacterial acrylic resin packaging material comprises the following raw materials in parts by weight: 120 parts methyl acrylate, 25 parts hydroxyethyl acrylate, 2 parts modified catechin polymer A, 0.7 parts natural vitamin E derivative, 0.3 parts osmium tetroxide nanosheets, 1.5 parts emulsifier, 0.5 parts wetting agent, and 0.6 parts photoinitiator; The preparation steps for food-grade antibacterial acrylic resin packaging materials are the same as in Example 1.

[0023] Example 3 The preparation methods for the modified catechin polymer and osmium tetroxide nanosheets are the same as in Example 1.

[0024] The preparation process of food-grade antibacterial acrylic resin packaging material is as follows: The food-grade antibacterial acrylic resin packaging material comprises the following raw materials in parts by weight: 100 parts methyl acrylate, 20 parts hydroxyethyl acrylate, 1.25 parts modified catechin polymer, 0.5 parts natural vitamin E derivative, 0.2 parts osmium tetroxide nanosheets, 1.0 part emulsifier, 0.3 parts wetting agent, and 0.4 parts photoinitiator; The preparation steps for food-grade antibacterial acrylic resin packaging materials are the same as in Example 1.

[0025] Comparative Example 1 The preparation method of osmium tetroxide nanosheets is the same as in Example 1.

[0026] The preparation process of food-grade antibacterial acrylic resin packaging material is as follows: The food-grade antibacterial acrylic resin packaging material comprises the following raw materials in parts by weight: 100 parts methyl acrylate, 20 parts hydroxyethyl acrylate, 0.5 parts natural vitamin E derivative, 0.2 parts osmium tetroxide nanosheets, 1.0 part emulsifier, 0.3 parts wetting agent, and 0.4 parts photoinitiator; The preparation of food-grade antibacterial acrylic resin packaging material is the same as in Example 1, except that no modified catechin polymer is added.

[0027] Comparative Example 2 The preparation method of the modified catechin polymer is the same as that in Example 1.

[0028] The preparation process of food-grade antibacterial acrylic resin packaging material is as follows: The food-grade antibacterial acrylic resin packaging material comprises the following raw materials in parts by weight: 100 parts methyl acrylate, 20 parts hydroxyethyl acrylate, 1.25 parts modified catechin polymer, 0.5 parts natural vitamin E derivative, 1.0 part emulsifier, 0.3 parts wetting agent, and 0.4 parts photoinitiator; The preparation of food-grade antibacterial acrylic resin packaging material is the same as in Example 1, except that osmium tetroxide nanosheets are not added.

[0029] Performance testing 1. Antibacterial activity test The prepared acrylic resin packaging material was cut into 2 cm × 2 cm sheets, and the surface was wiped with 75% ethanol and dried. 100 μL of a solution containing 10% ethanol was then evenly inoculated onto the surface of each sample. 6 CFU / mL of *Escherichia coli* and *Staphylococcus aureus* bacterial suspensions were coated with a sterile polyethylene film and incubated at room temperature for 24 h. After removing the film, the coating surface was rinsed with 10 mL of physiological saline, the eluent was collected and serially diluted, plated, and incubated for 24 h. The total number of viable bacteria in the eluent was calculated. Using the initial inoculum count as a control, the inhibition rate of each sample was calculated, and the results are shown in Table 1 below.

[0030] Table 1. Results of antibacterial rate As shown in Table 1, the antibacterial rates of the samples in Examples 1-3 of this invention are significantly higher than those in the comparative examples. In Example 1, the dosage of vitamin E and nanosheets is relatively low, yet the antibacterial rates reach 92% and 94%, respectively, indicating that the chemically anchored polyphenol structure can continuously release antibacterial activity. In Example 2, the antibacterial rates are further increased to 96% and 97%, indicating that increasing the content of active components can enhance the antibacterial effect. Example 3, using the midpoint ratio, has the highest antibacterial rate, reaching 99%, indicating that when balancing the synergistic effects of each component, the antibacterial, antioxidant, and barrier functions produce the best synergistic effect. In Comparative Example 1, due to the removal of catechin polymers, leaving only barrier and antioxidant components, the antibacterial rate drops to 60% and 62%, highlighting the key role of polyphenol grafting in antibacterial performance. In Comparative Example 2, only the nano-barrier component is removed, resulting in antibacterial rates of approximately 65% ​​and 68%, further demonstrating that although nanosheets are mainly used for gas barrier, their micro-network structure also contributes to the interfacial fixation and active release of antibacterial agents.

[0031] 2. Antioxidant capacity test The antioxidant properties of the coating were evaluated using the DPPH free radical scavenging method. 0.1 g of each of the acrylic resin packaging materials corresponding to Examples 1-3 and Comparative Examples 1-2 were weighed and extracted by ultrasonication in 10 mL of ethanol for 30 min. After standing and filtration, the sample extract was obtained. 2 mL of 0.1 mM DPPH methanol solution was mixed with 2 mL of the sample extract, and the mixture was reacted at room temperature in the dark for 30 min. The absorbance A was measured at a wavelength of 517 nm. 样本 Pure methanol and DPPH were used as controls for the determination of absorbance A. 对照 Calculate the DPPH removal rate using the formula below. The results are shown in Table 2 below.

[0032] Table 2 DPPH removal rate results As shown in Table 2, Example 3 achieved the highest scavenging rate of 95%, fully demonstrating the free radical scavenging effect of the vitamin E derivative in the chemically grafted network. Compared with Examples 1 and 2, the optimal synergistic ratio of vitamin E derivative, modified catechin polymer, and nanosheets in Example 3 enabled the antioxidant to react rapidly with DPPH in the coating matrix without reducing its activity due to excessive filler hindering diffusion. The scavenging rate of Comparative Example 1 was only 40%, indicating that chemical grafting or physical compounding alone is insufficient to achieve efficient antioxidant activity. The scavenging rate of Comparative Example 2 was only 60% after removing the nano-barrier network, indirectly confirming that the microporous channels constructed by the nanosheets not only improve the barrier performance but also promote the uniform distribution and release efficiency of the antioxidant.

[0033] 3. Oxygen transmission rate and water vapor transmission rate test Oxygen transmission rate (OTR) and water vapor transmission rate (WVTR) were tested as follows: The prepared acrylic resin packaging material was cut into 10 cm × 10 cm pieces and placed in an ASTM D3985 oxygen transmission rate tester. The test conditions were 23 °C, with pure oxygen introduced on the 0% RH side and nitrogen introduced on the other side. The change in oxygen concentration on the transmission side was recorded, and the OTR was calculated. The same path was used with an ASTM F1249 water vapor transmission rate tester, with pure water vapor introduced on the 38 °C, 90% RH side and dry nitrogen introduced on the other side, and the WVTR was measured. Each sample was measured three times, and the average value was taken. The results are shown in Table 3 below.

[0034] Table 3 Gas permeation performance test results As shown in Table 3, with the gradual increase of osmium tetroxide nanosheets G in the acrylic matrix, the OTR and WVTR of Examples 1–3 decreased significantly, especially in Example 3, where the OTR was 0.5 cm⁻¹. 3 ·m -2 ·d -1 ·kPa -1 WVTR is 4.0 g·m -2 ·d -1 The performance of the nanosheets was significantly better than that of Comparative Examples 1 and 2. This phenomenon can be attributed to the formation of disordered lattice channels in the polymer network by the nanosheets, which block the diffusion of gas molecules through narrow micropores. At the same time, the chemically grafted catechin polymers and the synergistically formulated vitamin E derivatives further filled the gaps in the channels, enhancing the sealing performance. Comparative Examples 1 and 2, lacking nano-barrier or antioxidant / filling synergistic components, exhibited significantly poor barrier performance.

[0035] 4. Mechanical and Adhesion Testing The coating adhesion was tested according to ASTM D3359 standard: acrylic resin packaging material was cut into 5 cm × 5 cm sheets, and a 6 × 6 parallel scribe line was used to score the coating surface with a 1 mm spacing between the scribe lines. Standard tape was then applied and quickly peeled off at a 90° angle. The number of scores was observed, and the adhesion grade was assessed according to ISO levels (0B–5B). Subsequently, the tensile properties of the coating were determined according to ASTM D882 standard: the coating film was prepared into 10 mm × 100 mm tensile specimens, which were then subjected to a load clamp and stretched at 50 mm / min until fracture at 25 °C and 50% RH. The maximum tensile strength (MPa) and elongation at break (%) were recorded. Each sample was tested five times, and the average value was taken as the final result. The results are shown in Table 4.

[0036] Table 4. Results of Mechanical Properties and Adhesion Tests As shown in Table 4, Example 1 exhibited good adhesion and tensile properties, thanks to the compatible network formed by the chemically grafted polyphenol polymer on the substrate surface. In Example 2, with the increase of nano-osmium tetroxide content, the coating cross-cut grade reached 5B, and the fracture strength and elongation were significantly improved, indicating that the nanosheets played a significant toughening role in the polymer matrix. Example 3, while taking into account the ratio of co-emulsifier and wetting agent, achieved the optimal micro-dispersion and network structure, further enhancing the mechanical toughness and adhesion stability of the coating. In contrast, the samples of Comparative Examples 1 and 2, which lacked key components, showed a decrease in adhesion grade and mechanical properties, fully demonstrating the comprehensive improvement effect of the synergistic construction and chemical anchoring of multifunctional components in this invention on coating performance.

[0037] 5. Aging resistance and accelerated aging tests The samples were alternately cycled in a UV aging chamber (UV 340 nm, 60 ℃) and a damp heat aging chamber (85 ℃, 85 % RH), with each cycle consisting of 24 h of UV irradiation and 24 h of damp heat treatment, for a total of 1000 h. Samples were taken out every 250 h, and the antibacterial rate, antioxidant rate, and oxygen permeability (OTR) were determined according to GB / T 21866-2008, DPPH method, and ASTM D3985, respectively. All tests were averaged three times, and the retention rate was calculated by comparing the average with the data before aging. The results are shown in Table 5 below.

[0038] Table 5 Results of Aging Resistance Tests As shown in Table 5, Example 1 maintained an antibacterial rate of 85% after 1000 h of aging, indicating that the grafted catechin polymer remained firmly attached under alternating UV and humid heat stress, continuously releasing antibacterial activity. Example 2 further improved the antibacterial and antioxidant retention rates to 90% and 85%, respectively, reflecting the protective effect of the nano-osmium tetroxide filling and micro-network structure on chemical bonds in a high-temperature and humid environment. Example 3 demonstrated the best overall stability, with an antibacterial retention rate of 95%, an antioxidant retention rate of 90%, and an OTR retention rate of 95%, reflecting the optimal ratio of each functional component and the synergistic toughening mechanism. The nanosheets not only blocked the erosion of the polymer chains by oxygen and water vapor but also limited the diffusion of free radicals. The vitamin E derivative continuously captured free radicals generated during the aging process, and the covalent anchoring structure of the catechin polymer ensured the integrity of the overall network. In contrast, Comparative Examples 1 and 2, due to the lack of key components, had network structures that were easily damaged, resulting in a significant decrease in performance retention. This further verifies the significant promoting effect of chemical grafting and multifunctional composite coating on the long-term stability of the coating in this invention.

[0039] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0040] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A food-grade antibacterial acrylic resin packaging material, characterized in that, It contains the following raw materials in parts by weight: 80-120 parts methyl acrylate, 15-25 parts hydroxyethyl acrylate, 0.5-2 parts modified catechin polymer, 0.3-0.7 parts natural vitamin E derivative, 0.1-0.3 parts osmium tetroxide nanosheets, 0.5-1.5 parts emulsifier, 0.1-0.5 parts wetting agent, and 0.2-0.6 parts photoinitiator.

2. The food-grade antibacterial acrylic resin packaging material according to claim 1, characterized in that, The preparation method of the modified catechin polymer specifically includes the following steps: S101. Dissolve catechin, propylene glycol dimethacrylate and azobisisobutyronitrile in tetrahydrofuran, disperse by ultrasonication and then transfer to a reaction vessel; S102. Purge nitrogen gas to replace the air in the reactor, and stir under an inert atmosphere, raising the temperature and stirring the reaction. S103. After the reaction is complete, cool to room temperature, pour the reaction solution into pre-cooled ethanol to precipitate, collect the precipitate after standing, remove impurities by washing, and place the collected solid in a vacuum drying oven to dry to constant weight to obtain the modified catechin polymer.

3. The food-grade antibacterial acrylic resin packaging material according to claim 1, characterized in that, The natural vitamin E derivative F is α-tocolate, the emulsifier D is polyvinyl alcohol modified acrylate, the wetting agent is a polycarboxylate complexing agent, and the photoinitiator is 2-hydroxy-2-methyl-1-phenylpropanone.

4. The food-grade antibacterial acrylic resin packaging material according to claim 1, characterized in that, The preparation method of the osmium tetroxide nanosheets specifically includes the following steps: S201. Osmium tetroxide octahydrate and ammonium nitrate are dissolved in ethylene glycol, ultrasonically dispersed, and then a small amount of sodium dodecylbenzenesulfonate is added as a surface stabilizer. S202. Transfer the dispersion to a high-pressure reactor with a polytetrafluoroethylene liner, add an equal volume of deionized water and seal the reactor for a high-temperature hydrothermal reaction. S203. Cool to room temperature, centrifuge the reaction product to separate the solid, wash the precipitate alternately with deionized water and ethanol, place the washed precipitate in a vacuum drying oven, dry to constant weight and collect to obtain the osmium oxide nanosheets.

5. A method for preparing a food-grade antibacterial acrylic resin packaging material, wherein the food-grade antibacterial acrylic resin packaging material is as described in any one of claims 1-4, characterized in that, Includes the following steps: S1. Emulsion preparation: Deionized water, methyl acrylate, hydroxyethyl acrylate, emulsifier, wetting agent and photoinitiator are put into a mixing tank, stirred and surfactant is added until a homogeneous emulsion is formed. S2. Grafting polymerization: Add the modified catechin polymer to the emulsion obtained in step S1 in batches, maintain stirring, and carry out emulsion polymerization grafting under an inert atmosphere. S3, Composite Addition: Vitamin E derivative and osmium tetroxide nanosheets are added sequentially to the polymer grafting mixture and stirred to achieve uniform dispersion; S4. Double curing: The obtained mixture is coated onto the substrate, first cured by ultraviolet light, then placed in a microwave cavity for microwave curing, and dried to obtain the food-grade antibacterial acrylic resin packaging material.

6. The method for preparing food-grade antibacterial acrylic resin packaging material according to claim 5, characterized in that, The surfactant used in step S1 is sodium dodecylbenzenesulfonate.

7. The method for preparing food-grade antibacterial acrylic resin packaging material according to claim 5, characterized in that, The microwave curing frequency is 2.45 GHz and the power is 0.5 kW.

8. The food-grade antibacterial acrylic resin packaging material according to claim 1, characterized in that, The material forms a micro-nano network structure in the coating by covalently grafting modified catechin polymers to achieve continuous release of antibacterial activity.

9. The food-grade antibacterial acrylic resin packaging material according to claim 1, characterized in that, The coating can maintain its functional properties for no less than 12 months under standard environmental conditions.

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