Starch composite polyvinyl alcohol packaging film base material, environment-friendly high-performance efficient antibacterial packaging film as well as application and preparation method of environment-friendly high-performance efficient antibacterial packaging film

Abstract

The embodiment of the invention provides a starch composite polyvinyl alcohol packaging film base material, an environment-friendly high-performance efficient antibacterial packaging film as well as application and a preparation method of the packaging film. The starch composite polyvinyl alcohol packaging film base material is obtained by carrying out silane coupling modified nano silicon dioxide reaction on modified polyvinyl alcohol and starch; wherein the modified polyvinyl alcohol is obtained by reacting polyvinyl alcohol with citric acid; the dosage of the silane coupling modified nano silicon dioxide is 1-7wt% of the total mass of the polyvinyl alcohol and the starch; the dosage of the citric acid is 5wt%-20wt% of the mass of the polyvinyl alcohol. The starch composite polyvinyl alcohol packaging film base material can be used for preparing an environment-friendly high-performance efficient antibacterial packaging film, and the prepared environment-friendly high-performance efficient antibacterial packaging film has good water resistance, thermal stability and mechanical property, has certain water solubility and dispersity, can ensure effective release of an antibacterial agent, and has a good antibacterial effect. The antibacterial rate on escherichia coli and staphylococcus aureus is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of food packaging materials, and more specifically to a starch composite polyvinyl alcohol packaging film base material, an environmentally friendly, high-performance, and efficient antibacterial packaging film, and applications and preparation methods thereof. Background Art

[0002] As people's living standards continue to improve, their concerns and demands for food safety are also increasing. Conventional protective packaging materials are unable to prevent microbial contamination and extend the shelf life of food. Furthermore, traditional petroleum-based plastic films are difficult to degrade, leading to serious environmental pollution. This is especially true for food packaging films, which are used in large quantities and have become a major source of solid waste. Therefore, the development of food packaging materials with antimicrobial and biodegradable properties has great market demand and prospects.

[0003] Common biodegradable materials include polyvinyl alcohol (PVA), polylactic acid (PLA), polyhydroxyalkanoates (PHA), and starch-based materials. These materials can be decomposed into carbon dioxide, water, and other harmless substances under the action of microorganisms. However, these materials themselves have low strength, poor thermal stability, and insufficient barrier properties to meet the requirements of packaging films. Traditional antimicrobial packaging films, on the other hand, are typically achieved by adding salt-based antimicrobial agents, such as sodium benzoate, to the plastic substrate. These antimicrobial agents are prone to deliquesce and precipitation, potentially posing food safety and environmental concerns. Furthermore, when organic synthetic and natural antimicrobial agents are added to hydrophobic substrates such as polyethylene and polylactic acid, the antimicrobial agents are difficult to release and their antimicrobial properties cannot be effectively exerted. Summary of the Invention

[0004] The purpose of the present invention is to provide a starch composite polyvinyl alcohol packaging film base material that can be used to prepare an environmentally friendly, high-performance, and efficient antibacterial packaging film, which can enable the prepared packaging film to have good mechanical properties, water resistance, and thermal stability, and can ensure the effective release of antibacterial agents.

[0005] The above-mentioned objectives are achieved by the following technical solutions.

[0006] The embodiment of the present invention provides a starch composite polyvinyl alcohol packaging film base material, wherein the starch composite polyvinyl alcohol packaging film base material is obtained by reacting modified polyvinyl alcohol and starch with silane coupling to modify nano-silicon dioxide; wherein the modified polyvinyl alcohol is obtained by reacting polyvinyl alcohol with citric acid; The amount of the silane coupling modified nano-silica is 1wt% to 7wt% of the total mass of the polyvinyl alcohol and the starch; The amount of citric acid used is 5wt% to 20wt% of the mass of the polyvinyl alcohol.

[0007] In some embodiments, the amount of the silane-coupling modified nano-silica is 1 wt% to 5 wt% of the total mass of the polyvinyl alcohol and the starch, preferably 1 wt% to 3 wt%, and more preferably 1 wt% to 2 wt%.

[0008] In some embodiments, the amount of citric acid is 8 wt % to 15 wt %, preferably 10 wt % to 20 wt %, more preferably 11 wt % to 15 wt %, and even more preferably 10 wt % to 12 wt % of the mass of the polyvinyl alcohol.

[0009] In some embodiments, the mass ratio of the citric acid to the silane-coupled modified nano-silica is 0.5-6:1, preferably 1-5:1, and more preferably 4.5-5:1.

[0010] Another embodiment of the present invention provides a method for preparing the starch composite polyvinyl alcohol packaging film base material as described above, comprising the following steps: Step a. Mix the polyvinyl alcohol solution with glycerol and stir evenly; Step b. mixing the resulting mixed solution with an acidic agent and adjusting the pH of the mixed solution to below 4; Step c. mixing the mixed solution after adjusting the pH value with citric acid and stirring the mixture to obtain the modified polyvinyl alcohol; Step d. Evenly mix the modified polyvinyl alcohol solution and the starch solution, add silane-coupled modified nano-silica and stir to react to obtain a starch composite polyvinyl alcohol packaging film base material.

[0011] In some embodiments, in step d, the reaction temperature is 45° C. to 55° C., and the reaction time is 1 h to 2 h; and / or, In step a, the amount of glycerol used is 5wt% to 30wt% of the mass of polyvinyl alcohol; and / or, In the step b, the acid agent is acetic acid; and / or, In the step b, the pH value is 1 to 3; and / or, In the step c, the reaction temperature is 60° C. to 95° C., and the reaction time is 8 h to 12 h.

[0012] Another embodiment of the present invention provides an environmentally friendly, high-performance, and efficient antibacterial packaging film, which is prepared by including the following components: chitosan, a silver metal organic framework, and the starch composite polyvinyl alcohol packaging film base material described above; wherein the amount of the chitosan is 10wt% to 50wt% of the total mass of the polyvinyl alcohol and the starch, and the amount of the silver metal organic framework is 1wt% to 10wt% of the total mass of the polyvinyl alcohol and the starch.

[0013] In some embodiments, the amount of chitosan is 20 wt% to 30 wt% of the total mass of polyvinyl alcohol and starch, and the amount of silver metal organic framework is 1 wt% to 4 wt% of the total mass of polyvinyl alcohol and starch; and / or, The preparation method of the silver metal organic framework comprises the following steps: mixing terephthalic acid and silver nitrate to obtain a suspension; The obtained suspension was poured into a polytetrafluoroethylene reactor and reacted at a temperature of 90°C to 110°C for 20h to 26h to obtain a silver metal organic framework suspension; The obtained silver metal organic framework suspension was centrifuged to obtain a precipitate, and the precipitate was dried at 55° C. to 65° C. for 10 h to 14 h.

[0014] Another embodiment of the present invention provides a use of the above-mentioned environmentally friendly, high-performance, and efficient antibacterial packaging film in food packaging materials.

[0015] Another embodiment of the present invention provides a method for preparing the environmentally friendly, high-performance, and efficient antibacterial packaging film as described above, comprising the following steps: mixing a starch composite polyvinyl alcohol packaging film base material solution and a chitosan solution to obtain a mixed solution; The obtained mixed solution is mixed with the silver metal organic framework to obtain a casting solution.

[0016] Compared with the prior art, the embodiments of the present invention have the following beneficial effects: In the present invention, polyvinyl alcohol is modified by citric acid to obtain modified polyvinyl alcohol, and the modified polyvinyl alcohol and starch are further modified by silane coupling modified nano-silica to obtain a starch composite polyvinyl alcohol packaging film base material. Under the specific dosage and ratio conditions of citric acid and silane coupling modified nano-silica, the obtained composite film has good comprehensive performance in mechanical properties, water resistance and thermal stability, has certain water solubility, can improve the cross-sectional flatness of the composite film, reduce bubbles and cracks in the composite film, and exhibits good compatibility.

[0017] Chitosan and silver metal organic framework are mixed as combined antibacterial agents with the starch composite polyvinyl alcohol packaging film base material to obtain a casting liquid. The obtained casting liquid has excellent film-forming properties and can make the film material after film formation have good water resistance, thermal stability and mechanical properties. At the same time, it has certain water solubility and dispersibility, can make the antibacterial agent evenly distributed and improve the release effect, facilitate the contact of the antibacterial agent with bacteria for sterilization, can ensure the effective release of the antibacterial agent, and improve the antibacterial rate against Escherichia coli and Staphylococcus aureus. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 a- Figure 1f is a microscopic morphology of the composite film obtained in Example 1 of the present invention when the addition ratios of citric acid and silane coupling modified nano-silica are uncrosslinked, 0:4, 1:3, 2:2, 3:1, and 4:0, respectively.

[0019] Figure 2 a- Figure 2 f is the antibacterial performance (Escherichia coli) test results of the composite membrane obtained in Example 2 of the present invention corresponding to the control group, the Ag-MOFs addition amounts of 0wt%, 1wt%, 2wt%, 3wt%, and 4wt%, and the chitosan addition amount of 30wt%.

[0020] Figure 3 These are the antibacterial performance (Staphylococcus aureus) test results of the composite membrane obtained in Example 2 of the present invention, corresponding to the control group, the Ag-MOFs addition amounts of 0wt%, 1wt%, 2wt%, 3wt%, and 4wt%, and the chitosan addition amount of 30wt%.

[0021] Figure 4 a- Figure 4 d is a microscopic morphology of the composite film obtained in Comparative Example 1 of the present invention when the citric acid addition amounts are 0 wt %, 10 wt %, 15 wt %, and 20 wt %.

[0022] Figure 5 a- Figure 5 d is a microscopic morphology of the composite film obtained in Comparative Example 2 of the present invention when the addition amounts of silane coupling modified nano-silica are 0wt%, 5wt%, 7wt% and 9wt% respectively.

[0023] Figure 6 a- Figure 6 g is the antibacterial performance (Escherichia coli) test results of the composite film obtained in Comparative Example 3 of the present invention, corresponding to the control group and the chitosan addition amounts of 0wt%, 10wt%, 20wt%, 30wt%, 40wt% and 50wt% respectively.

[0024] Figure 7 a- Figure 7 g is the antibacterial performance (Staphylococcus aureus) test results of the composite film obtained in Comparative Example 3 of the present invention corresponding to the control group and the chitosan addition amounts of 0wt%, 10wt%, 20wt%, 30wt%, 40wt% and 50wt% respectively.

[0025] Figure 8 a- Figure 8 c is a graph showing the antibacterial performance test (Escherichia coli) of the composite film obtained in Comparative Example 4 of the present invention with chitosan coating degrees of 25%, 50%, and 75%, respectively; Figure 8 d- Figure 8f is a graph showing the antibacterial performance test (Staphylococcus aureus) of the composite film obtained in Comparative Example 4 of the present invention with chitosan coating degrees of 25%, 50%, and 75%, respectively; Figure 8 g- Figure 8 i is a microscopic morphology of the composite film obtained in Comparative Example 4 of the present invention corresponding to chitosan coating degrees of 25%, 50%, and 75%, respectively.

[0026] Figure 9 These are the test results of the antibacterial properties (Escherichia coli (left), Staphylococcus aureus (right)) of the composite film obtained in Comparative Example 5 of the present invention corresponding to the addition amounts of silver metal organic framework of 1%, 2%, and 3%, respectively.

[0027] Figure 10 These are the test results of the antibacterial properties (Escherichia coli (left), Staphylococcus aureus (right)) of the composite film obtained in Comparative Example 6 of the present invention corresponding to the addition amounts of chitosan-coated Ag-MOFs of 1%, 2%, and 3%, respectively.

[0028] Figure 11 a- Figure 11 d is the antibacterial performance (Escherichia coli, Staphylococcus aureus) test result of the composite film obtained in Comparative Example 7 of the present invention corresponding to a chitosan addition amount of 30 wt % and an Ag-MOFs addition amount of 3%.

[0029] Figure 12 a- Figure 12 d is the antibacterial performance (Escherichia coli, Staphylococcus aureus) test result of the composite film obtained in Comparative Example 8 of the present invention corresponding to a chitosan addition amount of 30 wt % and an Ag-MOFs addition amount of 3%. DETAILED DESCRIPTION

[0030] To facilitate understanding of the present invention, the present invention will be described more fully below. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the present disclosure more thorough and comprehensive.

[0031] In the following examples, the experimental methods without specific conditions are generally carried out under conventional conditions or conditions recommended by the manufacturers. The various commonly used chemical reagents used in the examples are all commercially available products.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meanings as commonly understood by those skilled in the art to which this invention pertains. The terms used in this specification are for the purpose of describing specific embodiments only and are not intended to limit the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0033] The following are specific examples. Example 1

[0034] The preparation method of the starch composite polyvinyl alcohol packaging film base material provided in this embodiment comprises the following steps: Step ①: Weigh 1.5 g of polyvinyl alcohol (Tianjin Damao Chemical Reagent Factory, model 1799) and add it to 15 ml of deionized water. Add 0.4 g of propylene glycol (Tianjin Fuyu Fine Chemical Co., Ltd., analytical grade) for plasticization and stir at 95 °C for 2 h until fully dissolved.

[0035] Step ②: 2 ml of acetic acid (analytical grade, Tianjin Damao Chemical Reagent Factory) was added to step ① to adjust the pH to 1.5, and then citric acid (analytical grade, Tianjin Damao Chemical Reagent Factory) was added. The mixture was stirred at 65°C for 9 h to complete the esterification reaction to obtain modified polyvinyl alcohol. Step ③, weigh 0.5 g of soluble starch (Tianjin Tianli Chemical Reagent Co., Ltd.) and add it to 50 ml of deionized water, stirring at 95°C until fully dissolved to prepare a soluble starch solution for later use; Step ④: Mix the modified polyvinyl alcohol solution and the soluble starch solution, stir at 50 °C for 1 h until uniform, add silane-coupled modified nano-silica (Nano-SiO2, Zhejiang Zhiti Nano Micro New Materials Co., Ltd., 99.5%, VK-Sp30S), and stir at 50 °C for 1 h until uniform, to obtain a starch composite polyvinyl alcohol packaging film base material.

[0036] According to the above preparation method, under the conditions that the amount of citric acid is 15% of the mass of polyvinyl alcohol and the amount of silane-coupled silica is 7% of the total mass of polyvinyl alcohol and starch, the citric acid and silane-coupled silica are further divided into four equal parts, and the ratios of citric acid and silane-coupled silica are 0:4, 1:3, 2:2, 3:1, and 4:0, respectively. A cross-linking reaction without adding citric acid and silane-coupled silica is used as a control group to prepare a starch composite polyvinyl alcohol packaging film base.

[0037] The starch composite polyvinyl alcohol packaging film base material is evenly coated on a glass plate by a coating method and dried at room temperature to obtain Figure 1 The composite membrane shown. Figure 1 The results show that there are a lot of cracks in the polyvinyl alcohol and starch composite film before cross-linking modification (such as Figure 1 When a single silane-coupled silica is used as a cross-linking agent to modify polyvinyl alcohol, the silane-coupled silica forms a strong interaction with the matrix material, making it more regular and orderly, and the cracks in the cross section of the resulting membrane material gradually decrease (as shown in Figure 1). Figure 1As shown in b), when the silica addition amount is 7%, the effect is the best; when using only citric acid as a cross-linking agent, the film still has cracks (as shown in Figure 1 As shown in Figure f), when the citric acid addition amount is 15% of the mass of polyvinyl alcohol, the comprehensive performance is the best. When the addition ratio of citric acid to silane-coupled silica is 1:3, a large number of bubbles and a small number of cracks are generated in the cross-section of the composite film. The agglomeration of silane-coupled silica can cause the formation of bubbles. When the addition ratio is 2:2, the bubbles decrease, but the number of cracks increases significantly. At this addition amount, the cross-linking reaction between citric acid and polyvinyl alcohol makes the connection between molecular chains tighter, reducing the retention space of gas inside the film, thereby reducing the generation of bubbles. The uneven distribution of citric acid and nanoparticles leads to the concentration of internal stress in the film, which increases the number of cracks in the film cross-section. When the addition ratio is adjusted to 3:1, the cross-sectional flatness is significantly improved, the bubbles and cracks basically disappear, and the silane-coupled silica is more evenly distributed, showing the best compatibility. Example 2

[0038] The method for preparing the environmentally friendly, high-performance, and efficient antibacterial packaging film provided in this embodiment comprises the following steps: Step ①: Weigh 1.5g of polyvinyl alcohol and add it into 15ml of deionized water, add 0.4g of propylene glycol for plasticization, and stir at 95℃ for 2h until fully dissolved; Step ②, add 2 ml of acetic acid to the polyvinyl alcohol solution to adjust the pH value to 1.5, then add 0.1688 g of citric acid, and stir at 65° C. for 9 h to complete the esterification reaction to obtain modified polyvinyl alcohol; Step ③, weigh 0.5g of soluble starch and add it to 50ml of deionized water, stir at 95°C until fully dissolved, and prepare a soluble starch solution for later use; Step ④, the modified polyvinyl alcohol solution and the soluble starch solution were mixed, stirred at 50 ° C for 1 hour until uniform, 0.035g of silane-coupled modified nano-silica was added, and stirred at 50 ° C for 1 hour until uniform, to obtain a starch composite polyvinyl alcohol packaging film base material; Step 5: chitosan (CS, MacLean, degree of deacetylation ≥90%, MW~100000) was added to a 1wt% acetic acid solution according to 30wt% of the total amount of polyvinyl alcohol and starch, and stirred at 50°C for 12h to prepare a chitosan solution with a concentration of 2% for later use; Step ⑥, mixing the starch composite polyvinyl alcohol packaging film base material and the chitosan solution, stirring at 50° C. for 1 h until the mixture is uniform, to obtain a mixed solution of the chitosan-modified starch composite polyvinyl alcohol packaging film base material; Step 7: add the silver metal organic framework to the mixed solution of chitosan modified starch composite polyvinyl alcohol packaging film base material, and stir at room temperature for 1 hour until the mixture is uniform to obtain a casting solution.

[0039] According to the above preparation method, casting solutions were prepared according to the ratios of 0wt%, 1wt%, 2wt%, 3wt% and 4wt% of the total mass of polyvinyl alcohol and starch in the amount of the silver metal organic framework.

[0040] The preparation method of the silver metal organic framework (Ag-MOFs) is as follows: Step a: 2 mmol of terephthalic acid (analytical grade, Tianjin Damao Chemical Reagent Factory) and 2 mmol of silver nitrate (analytical grade, Tianjin Damao Chemical Reagent Factory) were added to 40 ml of deionized water and stirred at room temperature for 1 h until the mixture was uniform to obtain a suspension.

[0041] Step b: pour the obtained suspension into a 100 ml polytetrafluoroethylene-lined reactor and react at 100° C. for 24 h to obtain an Ag-MOFs (silver metal organic framework) suspension.

[0042] Step c: The Ag-MOFs suspension was washed three times with deionized water and anhydrous ethanol (analytical grade, Tianjin Damao Chemical Reagent Factory) by centrifugation, and the precipitate was dried in a vacuum drying oven at 60° C. for 12 h to obtain Ag-MOFs.

[0043] The obtained casting solution was evenly coated on a glass plate by a coating method and dried at room temperature to prepare a composite film, which was then subjected to an antibacterial test. Figure 2 and Figure 3 The results show that Ag-MOFs exhibit strong antibacterial properties against E. coli. At a 1 wt% addition, the composite membrane achieves 100% inhibition against E. coli, and this inhibition remains constant as the Ag-MOF addition level increases. With the addition of 1 wt% Ag-MOFs, the composite membrane's inhibition rate against Staphylococcus aureus increases from 96.7% to 99%, and as the Ag-MOF addition level increases, the composite membrane's inhibition rate against Staphylococcus aureus remains above 99.6%.

[0044] Comparative Example 1: The preparation method of the starch composite polyvinyl alcohol packaging film base material provided in this comparative example differs from that in Example 1 in that only citric acid is used to modify the starch composite polyvinyl alcohol packaging film base material, and the step of modifying the starch composite polyvinyl alcohol packaging film base material with silane coupling modified nano-silica is omitted. The other steps are the same as those in Example 1. The specific preparation method comprises the following steps: Step ①: Weigh 1.5g of polyvinyl alcohol and add it into 15ml of deionized water, add 0.4g of propylene glycol for plasticization, and stir at 95℃ for 2h until fully dissolved.

[0045] Step ②: Add 2 ml of acetic acid to step ①, and then add citric acid with a polyvinyl alcohol mass fraction of 0 wt%, 5 wt% (0.075 g), 10 wt% (0.150 g), 15 wt% (0.225 g), and 20 wt% (0.300 g), respectively, and stir at 65°C for 9 h to complete the esterification reaction to obtain modified polyvinyl alcohol; Step ③, weigh 0.5g of soluble starch and add it to 50ml of deionized water, stir at 95°C until fully dissolved, and prepare a soluble starch solution for later use; Step ④: Mix the modified polyvinyl alcohol solution with the soluble starch solution, and stir at 50° C. for 1 h until uniform, to obtain a starch composite polyvinyl alcohol packaging film base material.

[0046] The starch composite polyvinyl alcohol packaging film base material is evenly coated on a glass plate by a coating method and dried at room temperature to prepare the following Figure 4 The composite membrane shown: There are many cracks in the composite membrane. When the citric acid addition amount is 15 wt%, the cracks are reduced, but there are more bubbles in the membrane. When the citric acid addition amount is 20 wt%, the bubbles are reduced, but the cracks increase again.

[0047] Comparative Example 2 The preparation method of the starch composite polyvinyl alcohol packaging film base material provided in this comparative example differs from that in Example 1 in that the step of modifying the starch composite polyvinyl alcohol packaging film base material with citric acid is omitted, and only the step of modifying the starch composite polyvinyl alcohol packaging film base material with silane coupling modified nano-silica is used. The other steps are the same as those in Example 1. The specific preparation method comprises the following steps: Step ①: Weigh 1.5g of polyvinyl alcohol and add it into 15ml of deionized water, add 0.4g of propylene glycol for plasticization, and stir at 95℃ for 2h until fully dissolved.

[0048] Step ②, add 2 ml of acetic acid to step ①, and stir at 65°C for 9 hours to complete the reaction to obtain modified polyvinyl alcohol; Step ③, weigh 0.5g of soluble starch and add it to 50ml of deionized water, stir at 95°C until fully dissolved, and prepare a soluble starch solution for later use; Step ④, mix the modified polyvinyl alcohol solution with the soluble starch solution, stir at 50 ° C for 1 hour until uniform, add silane-coupled modified nano-silica with mass fractions of 0 wt%, 1 wt% (0.02 g), 3 wt% (0.06 g), 5 wt% (0.01 g), 7 wt% (0.14 g), and 9 wt% (0.18 g), respectively, and stir at 50 ° C for 1 hour until uniformly mixed to obtain a starch composite polyvinyl alcohol packaging film base.

[0049] The starch composite polyvinyl alcohol packaging film base material is evenly coated on a glass plate by a coating method and dried at room temperature to prepare the following Figure 5 The composite membrane shown: When single silane coupling modified nano-silica is used as a cross-linking agent to modify polyvinyl alcohol, the resulting membrane material has bubbles but no cracks. When the silica addition amount is 7%, the cross-section of the resulting membrane material has the least bubbles and is the smoothest.

[0050] Comparative Example 3 The preparation method of the environmentally friendly, high-performance, and efficient antibacterial packaging film provided in this comparative example differs from that of Example 2 in that chitosan is used as the antibacterial agent and no silver metal organic framework is added. The other aspects are the same as those of Example 2. The specific preparation method comprises the following steps: Step ①: Weigh 1.5g of polyvinyl alcohol and add it into 15ml of deionized water, add 0.4g of propylene glycol for plasticization, and stir at 95℃ for 2h until fully dissolved; Step ②: Add 2 ml of acetic acid to step ①, then add 0.1688 g of citric acid, and stir at 65°C for 9 h to complete the esterification reaction to obtain modified polyvinyl alcohol; Step ③, weigh 0.5g of soluble starch and add it to 50ml of deionized water, stir at 95°C until fully dissolved, and prepare a soluble starch solution for later use; Step ④, the modified polyvinyl alcohol solution and the soluble starch solution were mixed, stirred at 50 ° C for 1 hour until uniform, 0.035g of silane-coupled modified nano-silica was added, and stirred at 50 ° C for 1 hour until uniform, to obtain a starch composite polyvinyl alcohol packaging film base material; Step 5: Add chitosan to 1% acetic acid solution and stir at 50°C for 12 hours to prepare a 2% chitosan solution for later use; Step ⑥, mix the starch composite polyvinyl alcohol packaging film base material and the chitosan solution, stir at 50° C. for 1 h until the mixture is uniform, and obtain a casting solution of the chitosan-modified starch composite polyvinyl alcohol packaging film base material.

[0051] According to the above preparation method, a control group experiment (without any treatment) was set up, and the casting solution was prepared according to the ratio of chitosan addition of 0wt%, 10wt%, 20wt%, 30wt%, 40wt% and 50wt% of the total mass of polyvinyl alcohol and starch.

[0052] The obtained casting solution was evenly coated on a glass plate by a coating method and dried at room temperature to obtain a composite film, which was then subjected to an antibacterial test. Figure 6 and Figure 7The results shown in the figure show that when only chitosan was added without Ag-MOFs, the inhibition rate against Escherichia coli was 99.3%, and the inhibition rate against Staphylococcus aureus was 96.7%, and the antibacterial performance was inferior to that of Example 2. As the chitosan addition amount increased from 0 to 30 wt%, the number of ammonium radicals formed in the acidic environment increased, so the inhibition zone of Staphylococcus aureus and Escherichia coli showed an overall trend of expansion. As the concentration further increased, the inhibition zone of Staphylococcus aureus and Escherichia coli decreased. This is because the barrier effect of high concentration chitosan enhanced the interaction between chitosan molecules, forming aggregates or gel-like structures, reducing the effective contact area with the bacterial cell wall, and reducing the antibacterial effect. The composite film with a 50 wt% CS addition had an inhibition efficiency of only 74.3% and 54.6% against Escherichia coli and Staphylococcus aureus respectively.

[0053] Comparative Example 4 The preparation method of the environmentally friendly, high-performance, and efficient antibacterial packaging film provided in this comparative example differs from that in Example 2 in that the antibacterial agent is a chitosan-coated silver metal organic framework, and the rest is the same as in Example 2. The specific preparation method comprises the following steps: Step ①: Weigh 1.5g of polyvinyl alcohol and add it into 15ml of deionized water, add 0.4g of propylene glycol for plasticization, and stir at 95℃ for 2h until fully dissolved; Step ②: Add 2 ml of acetic acid to step ①, then add 0.1688 g of citric acid, and stir at 65°C for 9 h to complete the esterification reaction to obtain modified polyvinyl alcohol; Step ③, weigh 0.5g of soluble starch and add it to 50ml of deionized water, stir at 95°C until fully dissolved, and prepare a soluble starch solution for later use; Step ④, the modified polyvinyl alcohol solution and the soluble starch solution were mixed, stirred at 50 ° C for 1 hour until uniform, 0.035g of silane-coupled modified nano-silica was added, and stirred at 50 ° C for 1 hour until uniform, to obtain a starch composite polyvinyl alcohol packaging film base material; Step ⑤: Add the chitosan-coated silver metal organic framework to the modified starch composite polyvinyl alcohol packaging film base material according to the chitosan coating degree of 25%, 50% and 75% respectively, and stir at room temperature for 1 hour until the mixture is uniform to obtain a casting solution.

[0054] The preparation method of chitosan-coated silver metal organic framework is as follows: Step a: add 0.4 g, 1.0 g, and 1.5 g of chitosan to 2 ml of deionized water to prepare chitosan aqueous solutions with concentrations of 20%, 50%, and 75%, respectively; Step b: 0.04 g of Ag-MOFs (prepared as in Example 2) were added to the chitosan solution and stirred at room temperature in the dark for 4 h; Step c: drying the solution obtained in step b in an oven at 80° C. to obtain a chitosan-coated silver metal organic framework.

[0055] The obtained casting solution was evenly coated on a glass plate by a coating method and dried at room temperature to obtain a composite film, which was then subjected to an antibacterial test. Figure 8 The results shown are as follows: From the size of the inhibition zone, it can be seen that since chitosan coats Ag-MOFs, it is difficult for Ag-MOFs to be effectively released, and only the antibacterial property of chitosan can be exerted, and the antibacterial effect of Ag-MOFs cannot be effectively exerted. The overall antibacterial effect is not as good as that of Example 2.

[0056] Comparative Example 5: The preparation method of the environmentally friendly, high-performance, and efficient antibacterial packaging film provided in this comparative example differs from that of Example 2 in that polyvinyl alcohol is replaced with polylactic acid, and the rest is the same as Example 2. The specific preparation method comprises the following steps: Step ①: Weigh 2.0 g of polylactic acid and add it to 20 ml of dichloromethane (dichloromethane standard solution, 1 mol / L, MacLean), add 0.4 g of propylene glycol for plasticization, and stir at 95 °C for 2 h until fully dissolved; Step ②, the modified polylactic acid solution and the soluble starch solution were mixed, stirred at 50 ° C for 1 hour until uniform, 0.035g of silane-coupled modified nano-silica was added, and stirred at 50 ° C for 1 hour until the mixture was uniform, to obtain a starch composite polylactic acid base material; Step ③, chitosan was added to 1% acetic acid solution according to 30wt% of the total amount of polyvinyl alcohol and starch, and stirred at 50°C for 12h to prepare a chitosan solution with a concentration of 2% for standby use; Step ④, mixing the starch composite polylactic acid base material and the chitosan solution, stirring at 50° C. for 1 h until the mixture is uniform, to obtain a mixed solution of chitosan-modified starch composite polylactic acid base material; Step ⑤: Add the silver metal organic framework to the mixed solution of chitosan modified starch composite polylactic acid base material according to the addition amount of silver metal organic framework of 1%, 2% and 3% of the mass of polylactic acid respectively, and stir at room temperature for 1 hour until the mixture is uniform to obtain a casting solution.

[0057] The obtained composite film was evenly coated on a glass plate by a coating method and dried at room temperature to obtain an antibacterial test. Figure 9 The results shown: From the size of the inhibition zone, it can be seen that since PLA is difficult to dissolve in water, its swelling rate is 0%, making it difficult for the antibacterial agent to be released in PLA and unable to effectively exert its antibacterial effect.

[0058] Comparative Example 6: The preparation method of the environmentally friendly, high-performance, and efficient antibacterial packaging film provided in this comparative example differs from that in Example 2 in that polyvinyl alcohol is replaced with polylactic acid, and the antibacterial agent is replaced with a chitosan-coated silver metal organic framework. The specific preparation method comprises the following steps: Step ①: Weigh 2.0 g of polylactic acid and add it to 20 ml of dichloromethane, add 0.4 g of glycerol for plasticization, and stir at 95 ° C for 2 h until fully dissolved; Step ②, the modified polylactic acid solution and the soluble starch solution were mixed, stirred at 50 ° C for 1 hour until uniform, 0.035g of silane-coupled modified nano-silica was added, and stirred at 50 ° C for 1 hour until the mixture was uniform, to obtain a starch composite polylactic acid base material; Step ③, according to the chitosan-coated silver metal organic framework (the preparation method is the same as that of Comparative Example 4, and the chitosan coating degree is 50%), the addition amount is 1%, 2%, and 3% of the total mass of polylactic acid, respectively, and the chitosan-coated silver metal organic framework is added to the modified starch composite polyvinyl alcohol packaging film base material, and stirred at room temperature for 1 hour until the mixture is uniform to obtain a casting solution.

[0059] The obtained casting solution was evenly coated on a glass plate by a coating method and dried at room temperature to obtain a composite film, which was then subjected to an antibacterial test. Figure 10 The results shown are as follows: From the size of the inhibition zone, it can be seen that since PLA is insoluble in water, the swelling rate is 0%, and chitosan is coated on Ag-MOFs, it is difficult for chitosan and Ag-MOFs to be effectively released, and their antibacterial effect cannot be effectively exerted.

[0060] Comparative Example 7: The preparation method of the environmentally friendly, high-performance, and efficient antibacterial packaging film provided in this comparative example differs from that in Example 2 in that only citric acid is used to modify the starch composite polyvinyl alcohol packaging film base material, and the step of modifying the starch composite polyvinyl alcohol packaging film base material with silane coupling-modified nano-silica is omitted. The other steps are the same as in Example 2. The specific preparation method comprises the following steps: Step ①: Weigh 1.5 g of polyvinyl alcohol and add it into 15 mL of deionized water. Add 0.4 g of glycerol for plasticization and stir at 95°C for 2 h until fully dissolved. Step ②, 2 mL of acetic acid was added to the polyvinyl alcohol solution to adjust the pH to 1.5, and then 0.1688 g of citric acid was added, and the mixture was stirred at 65 ° C for 9 h to complete the esterification reaction to obtain modified polyvinyl alcohol; Step 3: Weigh 0.5 g of soluble starch and add it to 50 mL of deionized water. Stir at 95 °C until fully dissolved to prepare a soluble starch solution for later use. Step ④, mixing the modified polyvinyl alcohol solution with the soluble starch solution, stirring at 50 ° C for 1 h until uniform, to obtain a starch composite polyvinyl alcohol packaging film base; Step 5: Add 0.6 g of chitosan to a 1 wt% acetic acid solution and stir at 50 °C for 12 h to prepare a 2 wt% chitosan solution for later use; Step ⑥, mixing the starch composite polyvinyl alcohol packaging film base material and the chitosan solution, stirring at 50° C. for 1 h until the mixture is uniform, to obtain a mixed solution of the chitosan-modified starch composite polyvinyl alcohol packaging film base material; Step ⑦, adding 0.06 g of silver metal organic framework to the mixed solution of chitosan modified starch composite polyvinyl alcohol packaging film base material, stirring at room temperature for 1 hour until the mixture is uniform to obtain a casting solution.

[0061] The obtained casting solution was evenly coated on a glass plate by a coating method and dried at room temperature to obtain a composite film. The obtained membrane was subjected to plate count antibacterial test, and the results were as follows: Figure 11 The results shown are as follows: when a single citric acid cross-linked PVA / starch composite film is used, the antibacterial performance of the antibacterial film decreases after the addition of CS and Ag-MOFs. The antibacterial rate against Escherichia coli is 100%, but the antibacterial rate against Staphylococcus aureus is 99.14%, which is lower than that in Example 2. At the same time, the tensile strength of the obtained film is also worse than that of the double-cross-linked antibacterial film (Table 1).

[0062] Comparative Example 8: The preparation method of the environmentally friendly, high-performance, and efficient antibacterial packaging film provided in this comparative example differs from that in Example 2 in that only the starch composite polyvinyl alcohol packaging film base is modified with silane-coupled modified nano-silica, and the step of modifying the starch composite polyvinyl alcohol packaging film base with citric acid is omitted. The other steps are the same as in Example 2. The specific preparation method comprises the following steps: Step ①: Weigh 1.5 g of polyvinyl alcohol and add it into 15 mL of deionized water. Add 0.4 g of glycerol for plasticization and stir at 95°C for 2 h until fully dissolved. Step ②: Weigh 0.5 g of soluble starch and add it to 50 mL of deionized water. Stir at 95 °C until fully dissolved to prepare a soluble starch solution for later use. Step ③, the polyvinyl alcohol solution and the soluble starch solution were mixed, stirred at 50 ° C for 1 hour until uniform, 0.035g of silane coupling modified nano-silica was added, and stirred at 50 ° C for 1 hour until uniform, to obtain a starch composite polyvinyl alcohol packaging film base material; Step ④, add 0.6 g of chitosan to 1 wt% acetic acid solution, stir at 50°C for 12 h, and prepare a chitosan solution with a concentration of 2% for later use; Step 5: Mix the starch composite polyvinyl alcohol packaging film base material and the chitosan solution, and stir at 50° C. for 1 hour until the mixture is uniform, to obtain a mixed solution of the chitosan-modified starch composite polyvinyl alcohol packaging film base material; Step ⑥, add 0.06 g of silver metal organic framework to the mixed solution of chitosan modified starch composite polyvinyl alcohol packaging film base material, and stir at room temperature for 1 hour until the mixture is uniform to obtain a casting solution.

[0063] The obtained casting solution was evenly coated on a glass plate by a coating method and dried at room temperature to obtain a composite film. The obtained film was subjected to an antibacterial test and the results were as follows: Figure 12 The results show that when a single-crosslinked PVA / starch composite film modified by silane coupling is used, the antibacterial performance of the antibacterial film with the addition of chitosan and Ag-MOFs is reduced, with an inhibition rate of 83.89% against Staphylococcus aureus and 97.89% against Escherichia coli. This is because citric acid itself has certain antibacterial properties. Using citric acid as a crosslinking agent can improve the water resistance and antibacterial properties of the composite film. However, the single-crosslinked composite film modified by silane coupling only has two antibacterial agents to exert its antibacterial properties, so the antibacterial performance is inferior to that of Example 2. At the same time, the tensile strength of the resulting film is also lower than that of Example 2 (Table 1).

[0064] The casting solutions obtained in the Examples and Comparative Examples were applied layer by layer to a glass plate using a 20 μm diameter wire rod. After each coating layer, the glass plate was placed in a constant temperature and humidity chamber at 40°C and 40% RH for 1 hour to dry. The composite film was then applied. After all coating solutions were applied and dried, the resulting composite film was subjected to the following mechanical and antibacterial property tests.

[0065] The test method for tensile strength is: Using a 100N microcomputer-controlled electronic universal testing machine and following the GB / T1040.3-2006 standard, the film was cut with scissors into rectangles approximately 20 mm wide and 100 mm long. The sample length between the two clamps was set to 50-70 mm. Thickness was measured at three different points using a micrometer screw. Films with uniform thickness and no obvious defects were selected for mechanical property testing. The tensile speed was set to 30 mm / min, and data was recorded when the film broke.

[0066] (1) Tensile strength During the tensile process, the material enters the strengthening stage after the yield stage, and the transverse cross-sectional size is significantly reduced. The maximum force (F b ), divided by the original cross-sectional area of ​​the specimen (S0), is called the tensile strength or ultimate strength (R m ), unit is N / mm 2 Or MPa. The tensile strength calculation formula (1) is obtained as follows:

[0067] Where R m——Elongation at break, in MPa F b ——The maximum tensile force when the film breaks or fails, in N; b——film width, in mm; d——film thickness, in mm.

[0068] (2) Elongation at break The stress and deformation of any material always exist and develop simultaneously. Under the action of tensile force, the material will generally stretch. The elongation of the fiber when it is stretched to break is called the elongation at break, represented by e, and the unit is percentage (%). The elongation at break can be used to express the elongation deformation capacity of the film when it is subjected to the maximum load. From this, we can know the formula for the elongation at break of the film (2):

[0069] Where e is the elongation at break of the film; L - the maximum length of the film before breaking, in mm; L0 - the length of the film between the clamps before stretching, in mm The test method for swelling rate is: Cut the dried composite film into 2×2 cm 2 The initial weight of the composite membrane was recorded as m0 (mg). The composite membrane was immersed in deionized water for 24 h until fully swollen. The surface moisture was wiped off with absorbent paper. The weight was then weighed and recorded as m1 (mg). The swelling ratio (S) of the composite membrane in water was obtained from formula (3).

[0070]

[0071] The test method for the initial decomposition temperature is: The thermal stability of the composite membrane was tested using a thermogravimetric analyzer. 8 mg of the dried composite membrane was heated from 35°C to 700°C at a heating rate of 10 K / min under a nitrogen atmosphere. The initial decomposition temperature was determined as the temperature at which the membrane initially lost weight on the thermogravimetric curve.

[0072] Antibacterial test: inhibition zone method 3 g of tryptic soy broth (TSB) was dissolved in 100 mL of deionized water, 8 g of agar powder was dissolved in 400 mL of deionized water, and 39.6 g of nutrient agar was dissolved in 1200 mL of deionized water. Each solution was stirred at 98°C for 1 hour until completely dissolved. The three solutions and the necessary experimental equipment, including an 8 mm Oxford cup, were sterilized in an autoclave at 121°C for 15 minutes. Staphylococcus aureus and Escherichia coli bacterial cultures were diluted to 108–109 cfu / mL using the cooled TSB solution. The cultures were then serially diluted 100-fold and used for further preparation. 10 mL of agar was poured into a Petri dish. After the agar cooled and solidified, the Oxford cup was placed in the center. A uniform mixture of 1500 µl of bacterial culture and 30 mL of nutrient agar solution was poured onto the outside of the Oxford dish. After cooling and solidification, the Oxford cup was removed and 180 µl of casting solution was injected into the hole. Each experiment was repeated three times, and the average inhibition zone size was calculated. The inhibition zone sizes are shown in Table 1.

[0073] Antimicrobial testing: plate count method Dissolve 3g of tryptic soy broth (TSB) in 100ml of deionized water and 12.45g of crystal violet red bile agar (VRBA) in 300ml of deionized water. Stir each at 98°C for 1h until completely dissolved. Sterilize the TSB solution, LB nutrient agar, and all experimental equipment in an autoclave at 121°C for 15min. Dilute Staphylococcus aureus and Escherichia coli cultures to 106-107 cfu / ml using the cooled TSB solution. Then, serially dilute the cultures 100-fold for later use. Pour 30ml of VRBA solution and 30ml of LB nutrient agar into disposable plastic Petri dishes, cool, and solidify. Co-incubate 2ml of the diluted culture with 20mg of sterilized casting solution at 37°C and 70% RH for 2h. Spread 100µl of the co-incubated culture onto the solidified culture medium. Incubate inverted at 37°C and 70% RH for 24h before counting.

[0074] Results: The performance test results of the composite membranes of the embodiment and the comparative example are shown in Table 1 below.

[0075] Table 1

[0076]

[0077]

[0078]

[0079]

[0080] The experimental results of the above examples and comparative examples show that: by comparing Example 1 with Comparative Examples 1-2, it can be seen that the modified polyvinyl alcohol obtained by modifying polyvinyl alcohol with citric acid, and then further modifying the modified polyvinyl alcohol and starch with silane-coupled modified nano-silica to obtain a starch composite polyvinyl alcohol packaging film base, compared with modifying the starch composite polyvinyl alcohol packaging film base with only citric acid or modifying the starch composite polyvinyl alcohol packaging film base with only silane-coupled modified nano-silica, the resulting composite film has better comprehensive mechanical properties, water resistance, and thermal stability, and has a certain degree of water solubility. When the addition ratio of citric acid to silane-coupled silica is 3:1, the cross-sectional flatness of the composite film is significantly improved, bubbles and cracks are basically eliminated, the silane-coupled silica is more evenly distributed, and it exhibits the best compatibility and mechanical properties.

[0081] From Example 2 Figure 2 It can be seen that the Ag-MOFs / CS combined antibacterial agent exhibited a strong antibacterial activity against Escherichia coli. When the addition amount was only 1%, the antibacterial efficiency of the composite membrane against Escherichia coli reached 100% (e.g. Figure 2 (a)), and the antibacterial efficiency remains at 100% with the increase of the amount of Ag-MOFs added. Figure 2 As shown in (b), after adding 1% Ag-MOFs, the antibacterial efficiency of the composite membrane against Staphylococcus aureus increased from 96.7% to 99.0%, and as the amount of Ag-MOFs added increased, the antibacterial efficiency of the composite membrane against Staphylococcus aureus was always greater than 99.6%. It can be seen from the results in Table 1 that although the toughness of the composite membrane decreased after adding the combined antibacterial agent Ag-MOFs / CS, the tensile strength was enhanced, and the comprehensive performance was high.

[0082] A comparison between Example 2 and Comparative Example 3 shows that chitosan alone, when used as the antimicrobial agent in the composite membrane casting solution, has a maximum antimicrobial efficiency of 99.3% against E. coli, but only 96.7% against Staphylococcus aureus. However, when Ag-MOFs and chitosan are used as the antimicrobial agents in the casting solution, the antimicrobial efficiency against E. coli and Staphylococcus aureus is consistently greater than 99%, demonstrating a synergistic antimicrobial effect.

[0083] By comparing Example 2 and Comparative Example 4, it can be seen that the composite membrane of the casting liquid obtained by directly blending the starch composite polyvinyl alcohol packaging film base solution with the chitosan solution and the silver metal organic framework has a higher antibacterial efficiency than the composite membrane of chitosan-coated Ag-MOFs obtained by the coating method.

[0084] By comparing Example 2 with Comparative Examples 5-6, it can be seen that when the base film material is replaced with polylactic acid, under the same antibacterial agent addition conditions, the antibacterial performance of the obtained film is poor. This is mainly because the base film encapsulates the antibacterial agent, while the base film itself is difficult to dissolve or insoluble in water, with a swelling rate of 0, and chitosan encapsulates Ag-MOFs, making it difficult for chitosan and Ag-MOFs to be effectively released, and they cannot effectively exert their antibacterial effect.

[0085] By comparing Example 2 with Comparative Examples 7-8, it can be seen that when only citric acid or silica is used to modify the polyvinyl alcohol / starch composite film, and chitosan and Ag-MOFs are used as antibacterial agents, the antibacterial properties and mechanical properties of the obtained film are inferior to those of Example 2.

[0086] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0087] The above-described embodiments merely illustrate several implementations of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A starch composite polyvinyl alcohol packaging film base material, characterized in that: The starch composite polyvinyl alcohol packaging film base material is obtained by reacting modified polyvinyl alcohol with starch through silane coupling to modify nano-silicon dioxide; wherein the modified polyvinyl alcohol is obtained by reacting polyvinyl alcohol with citric acid; The amount of the silane coupling modified nano-silica is 1 wt% to 7 wt% of the total mass of the polyvinyl alcohol and the starch; The amount of citric acid used is 5wt% to 20wt% of the mass of the polyvinyl alcohol.

2. The starch composite polyvinyl alcohol packaging film base material according to claim 1, characterized in that: The amount of the silane coupling modified nano-silica is 1 wt% to 5 wt% of the total mass of the polyvinyl alcohol and the starch, preferably 1 wt% to 2 wt%.

3. The starch composite polyvinyl alcohol packaging film base material according to claim 1, characterized in that: The amount of citric acid used is 10 wt% to 20 wt% of the mass of the polyvinyl alcohol, preferably 10 wt% to 12 wt%.

4. The starch composite polyvinyl alcohol packaging film base material according to claim 1, characterized in that: The mass ratio of the citric acid to the silane-coupled modified nano-silica is 0.5-6:1, preferably 1-5:1, and more preferably 4.5-5:

1.

5. The method for preparing the starch composite polyvinyl alcohol packaging film base material according to any one of claims 1 to 4, characterized in that: The steps include: Step a. Mix the polyvinyl alcohol solution with glycerol and stir evenly; Step b. mixing the resulting mixed solution with an acidic agent and adjusting the pH of the mixed solution to below 4; Step c. mixing the mixed solution after adjusting the pH value with citric acid and stirring the mixture to obtain the modified polyvinyl alcohol; Step d. Evenly mix the modified polyvinyl alcohol solution and the starch solution, add silane-coupled modified nano-silica and stir to react to obtain a starch composite polyvinyl alcohol packaging film base material.

6. The preparation method according to claim 5, wherein In the step d, the reaction temperature is 45°C to 55°C, and the reaction time is 1h to 2h; and / or, In step a, the amount of glycerol is 5wt% to 30wt% of the mass of polyvinyl alcohol; and / or, In the step b, the acid agent is acetic acid; and / or, In the step b, the pH value is 1 to 2; and / or, In the step c, the reaction temperature is 60° C. to 95° C., and the reaction time is 8 h to 12 h.

7. An environmentally friendly, high-performance, and efficient antibacterial packaging film, characterized in that: The preparation comprises the following components: Chitosan, silver metal organic framework and the starch composite polyvinyl alcohol packaging film base material according to any one of claims 1 to 4; The amount of chitosan is 10 wt% to 50 wt% of the total mass of polyvinyl alcohol and starch, and the amount of silver metal organic framework is 1 wt% to 10 wt% of the total mass of polyvinyl alcohol and starch.

8. The environmentally friendly, high-performance, and efficient antibacterial packaging film according to claim 7, characterized in that: The amount of chitosan is 20 wt% to 30 wt% of the total mass of polyvinyl alcohol and starch, and the amount of silver metal organic framework is 1 wt% to 4 wt% of the total mass of polyvinyl alcohol and starch; and / or, The preparation method of the silver metal organic framework comprises the following steps: mixing terephthalic acid and silver nitrate to obtain a suspension; The obtained suspension was poured into a polytetrafluoroethylene reactor and reacted at a temperature of 90°C to 110°C for 20h to 26h to obtain a silver metal organic framework suspension; The obtained silver metal organic framework suspension was centrifuged to obtain a precipitate, and the precipitate was dried at 55° C. to 65° C. for 10 h to 14 h.

9. Use of the environmentally friendly, high-performance, and efficient antibacterial packaging film according to any one of claims 7 to 8 in food packaging materials.

10. The method for preparing the environmentally friendly, high-performance, and efficient antibacterial packaging film according to any one of claims 7 to 8, characterized in that: The steps include: mixing a starch composite polyvinyl alcohol packaging film base material solution and a chitosan solution to obtain a mixed solution; The obtained mixed solution is mixed with the silver metal organic framework to obtain a casting solution.

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