An environmentally friendly biodegradable antibacterial film and its preparation method

Abstract

This invention relates to the field of polymer composite materials technology, specifically to an environmentally friendly biodegradable antibacterial film and its preparation method, comprising the following raw materials in parts by weight: 40-60 parts polylactic acid, 20-40 parts polyadipic acid, 5-15 parts additive A, 3-10 parts additive B, 2-8 parts polyethylene glycol, and 1-5 parts polyethylene wax. In this invention, additive A is a composite of loofah charcoal loaded with tea polyphenols and quaternary ammonium salt-modified chitosan, combined with eugenol to construct a synergistic antibacterial system. The porous structure of the loofah charcoal adsorbs pathogens and directionally releases tea polyphenols and eugenol, thus enhancing the antibacterial efficacy of the film through a dual effect. Additive B is a composite powder prepared by modifying cassava starch with active ingredients from Sichuan pepper seeds extracted by supercritical CO2. The composite powder improves the toughness and thermal stability of the film and enhances the processing fluidity of polyadipic acid. The two work synergistically to endow the film with excellent film-forming properties, mechanical strength, and durable antibacterial properties.

Description

Technical Field

[0001] This invention relates to the field of polymer composite materials technology, specifically to an environmentally friendly biodegradable antibacterial film and its preparation method. Background Technology

[0002] Antibacterial films are a new type of functional material that inhibits bacterial growth and reproduction by introducing active ingredients such as silver ions, photocatalysts, or natural antibacterial agents into traditional film substrates. The principle is to destroy the bacterial cell wall or interfere with the microbial metabolic process, thereby effectively preventing the growth of bacteria on the surface and cross-infection. The products are widely used in medical packaging, food preservation, household appliances, and public facilities, and can significantly extend the shelf life of items, reduce the risk of bacterial transmission, and provide a convenient and efficient solution for health protection and hygiene management.

[0003] In existing technologies, biodegradable antibacterial films often employ inorganic or chemically synthesized antibacterial agents, which suffer from poor compatibility and weak antibacterial efficacy. When some natural antibacterial materials are directly added, uneven dispersion and weak adhesion to the matrix can easily lead to a decline in the film's mechanical properties and an uncontrollable degradation rate. Therefore, this invention provides an environmentally friendly biodegradable antibacterial film and its preparation method. Summary of the Invention

[0004] The purpose of this invention is to provide an environmentally friendly biodegradable antibacterial film and its preparation method. The environmentally friendly biodegradable antibacterial film prepared by this invention not only has good biodegradability but also has long-lasting antibacterial properties, effectively improving the overall performance of the antibacterial film.

[0005] To achieve the above objectives, the present invention provides the following technical solution: In the first aspect, an environmentally friendly biodegradable antibacterial film comprises the following raw materials in parts by weight: 40-60 parts polylactic acid, 20-40 parts polyadipic acid, 5-15 parts additive A, 3-10 parts additive B, 2-8 parts polyethylene glycol and 1-5 parts polyethylene wax. The raw materials for additive A include modified chitosan, acetic acid solution, additives, and eugenol; The raw materials for additive B include hydroxyl-terminated polycaprolactone, epichlorohydrin, tetrabutylammonium bromide, composite powder, and ammonium persulfate.

[0006] Further, the additive A is prepared by the following method: modified chitosan and acetic acid solution are mixed at a mass ratio of 1:(19-49) to obtain a first mixture, which is set aside for later use. The additive is mixed with anhydrous ethanol at a mass ratio of 1:(5-10) to obtain a second mixture. The first mixture and the second mixture are stirred and mixed at 40-60℃, the pH is adjusted to 8.0-9.0, and the reaction is carried out for 2-4 hours. The residue is obtained by centrifugation and dried. The dried residue is mixed with anhydrous ethanol at a mass ratio of 1:(8-12), eugenol is added, and the reaction is carried out at 30-50℃ for 6-12 hours. After centrifugation and drying, additive A is obtained. The mass concentration of the acetic acid solution is 1-3%, and the mass of eugenol is 20-40% of the mass of the residue.

[0007] Further, the additive is prepared by the following method: Loofah sponge is dried at 80-100℃ for 12-24 hours, then transferred to a tube furnace and heated to 300-400℃ at a rate of 5-10℃ / min under a nitrogen atmosphere. The temperature is maintained for 1-2 hours, then potassium hydroxide is added, and the temperature is raised to 600-800℃ for 2-3 hours. After cooling, the reaction product is removed and washed with 0.5-1 mol / L hydrochloric acid solution until neutral, then rinsed with deionized water. Wash the loofah sponge 3-5 times with water and dry it at 80-100℃ to obtain charcoal. Mix the charcoal sponge with tea polyphenol solution at a mass ratio of 1:(5-10) and stir at 200-500 rpm for 12-24 hours at 25-35℃. Filter the mixture and dry the filter residue at 50-70℃ for 8-12 hours to obtain the additive. The mass of potassium hydroxide is 2-4 times the mass of the loofah sponge, and the mass concentration of the tea polyphenol solution is 10-20%.

[0008] Further, the modified chitosan is prepared by the following method: chitosan and isopropanol are mixed at a mass ratio of 1:(5-10), and a sodium hydroxide solution with a mass concentration of 20-30% is added under nitrogen protection. The mixture is reacted at room temperature for 1-3 hours, and then 2,3-epoxypropyltrimethylammonium chloride is added dropwise. The mixture is reacted at 60-80°C for 8-12 hours, filtered, the filter residue is collected, and dried to obtain the modified chitosan. The mass of the sodium hydroxide solution is 0.5-1 times the mass of the chitosan, and the molar ratio of 2,3-epoxypropyltrimethylammonium chloride to chitosan is (1-2):1.

[0009] Further, the additive B is prepared by the following method: hydroxyl-terminated polycaprolactone and epichlorohydrin are mixed at a mass ratio of 1:(3-6), tetrabutylammonium bromide is added, and the mixture is reacted at 80-100℃ for 4-6 hours. The mixture is then distilled under reduced pressure for 1-3 hours to obtain an intermediate product, which is set aside for later use. The composite powder is mixed with deionized water at a mass ratio of 1:(4-9) to obtain a suspension. Ammonium persulfate is added, and the mixture is activated by stirring at 70-90℃ for 20-40 minutes. The intermediate product is added dropwise, and the mixture is reacted for 3-5 hours. After centrifugation, washing, and drying, additive B is obtained.

[0010] Further, the composite powder is prepared by the following method: cassava starch and anhydrous ethanol are mixed at a mass ratio of 1:(4-8), reactants and a sodium hydroxide solution with a mass concentration of 12-15% are added, and the mixture is reacted in a water bath at 15-25℃ for 1.2-1.5h. Then sodium chloroacetate is added, and the mixture is reacted at 50-70℃ for 4-6h. The pH is adjusted to 6.5-7.0 with 0.5-1mol / L dilute hydrochloric acid, the residue is collected by filtration, and the residue is dried to obtain the composite powder.

[0011] Further, the reaction material is prepared by the following method: Sichuan pepper seeds are crushed and passed through a 40-80 mesh sieve to obtain Sichuan pepper seed powder. The Sichuan pepper seed powder is transferred into a supercritical CO2 extraction vessel, and a 65% (v / v) ethanol solution is added. The mixture is reacted at 25-35 MPa and 40-50 °C for 1-3 h. The reaction solution is collected and concentrated under reduced pressure at 40-50 °C for 1-3 h to obtain the reaction material.

[0012] Furthermore, the mass of the tetrabutylammonium bromide is 0.5-2% of the mass of the hydroxyl-terminated polycaprolactone, the mass of the ammonium persulfate is 0.5-1.5% of the mass of the composite powder, and the mass of the intermediate product is 30-50% of the mass of the composite powder.

[0013] Furthermore, the mass of the sodium hydroxide solution is 20-40% of the mass of the cassava starch, the molar ratio of sodium chloroacetate to cassava starch is (0.2-0.5):1, and the mass of the reactant is 5-8% of the mass of the cassava starch.

[0014] Secondly, the present invention provides a method for preparing an environmentally friendly biodegradable antibacterial film, characterized by comprising the following steps: Step 1: Add polylactic acid, polyadipic acid, additive A, additive B, polyethylene glycol and polyethylene wax into a high-speed mixer and mix for 10-20 minutes at a speed of 300-800 rpm to obtain a premix. Step 2: Transfer the premixed material into a twin-screw extruder, melt-blend at 150-190℃, and then extrude and granulate to obtain film granules; Step 3: The film granules are formed at 160-200℃ using a casting machine or blown film machine, and then cooled to obtain an environmentally friendly biodegradable antibacterial film.

[0015] Compared with the prior art, the beneficial effects of the present invention are: 1. In this invention, additive A is a compound of charred loofah containing tea polyphenols and quaternary ammonium salt modified chitosan, which, together with eugenol, forms a synergistic antibacterial system. The modified chitosan, with its cationic structure, disrupts the integrity of bacterial cell membranes, while the porous structure of the loofah adsorbs pathogens and releases tea polyphenols and eugenol in a directional manner. This dual action enhances the antibacterial efficacy of the film. At the same time, the modified chitosan and loofah char improve the compatibility with the polylactic acid matrix, enhance the mechanical properties and degradation rate of the film, and achieve a balance between environmental friendliness and antibacterial properties.

[0016] 2. In this invention, additive B is prepared by modifying cassava starch with active ingredients from Sichuan pepper seeds extracted by supercritical CO2 to obtain a composite powder. After grafting and cross-linking with terminal hydroxyl polycaprolactone, a flexible cross-linked network is formed inside the film. The natural active ingredients of Sichuan pepper seeds have a long-lasting antibacterial effect and are safe and biodegradable. The composite powder improves the toughness and thermal stability of the film and improves the processing fluidity of polyadipate. The two work synergistically to give the film excellent film-forming properties, mechanical strength and long-lasting antibacterial properties. It contains few harmful additives and meets the requirements of environmental protection and biodegradability.

[0017] 3. In this invention, additives A and B work together. Additive A, with modified chitosan, tea polyphenol-supported loofah charcoal, and eugenol as its core, provides rapid and broad-spectrum antibacterial and interfacial compatibility effects. Additive B, with modified composite powder of active ingredients from Sichuan pepper seeds as its main functional component, imparts long-lasting antibacterial, toughening and reinforcing, and processing stability properties. After being combined, the two form a uniform interpenetrating network in the polylactic acid and polyadipate matrix, which improves the antibacterial rate and antibacterial durability of the film, and effectively improves the mechanical strength, toughness, and thermal stability of the matrix. At the same time, they synergistically regulate the degradation rate, achieving a balance between complete degradability and environmental safety, and solving the technical problem that a single functional component cannot simultaneously achieve effective antibacterial, excellent mechanical properties, and stable processing. Attached Figure Description

[0018] Figure 1 The present invention provides a flowchart of an environmentally friendly biodegradable antibacterial film and its preparation method. Detailed Implementation

[0019] 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.

[0020] It should be noted that the raw materials used in the following embodiments are all commercially available. Example 1

[0021] Preparation of the additive: After drying the loofah sponge at 80℃ for 12h, it was transferred to a tube furnace and heated to 300℃ at a rate of 5℃ / min under a nitrogen atmosphere. After holding the temperature for 1h, potassium hydroxide was added, and the temperature was raised to 600℃ for 2h. After cooling, the reaction product was taken out and washed with 0.5mol / L hydrochloric acid solution until neutral, and then washed three times with deionized water. It was dried at 80℃ to obtain loofah sponge charcoal. The loofah sponge charcoal and tea polyphenol solution were mixed at a mass ratio of 1:5 and stirred at 25℃ and 200rpm for 12h. After filtration, the filter residue was dried at 50℃ for 8h to obtain the additive. The mass of potassium hydroxide was twice the mass of loofah sponge, and the mass concentration of tea polyphenol solution was 10%.

[0022] Preparation of modified chitosan: Chitosan and isopropanol were mixed at a mass ratio of 1:5. A 20% sodium hydroxide solution was added under nitrogen protection and the mixture was reacted at room temperature for 1 hour. Then, 2,3-epoxypropyltrimethylammonium chloride was added dropwise and the mixture was reacted at 60°C for 8 hours. The mixture was filtered, the residue was collected, and dried to obtain modified chitosan. The mass of the sodium hydroxide solution was 0.5 times the mass of the chitosan, and the molar ratio of 2,3-epoxypropyltrimethylammonium chloride to chitosan was 1:1.

[0023] Preparation of Additive A: Modified chitosan and acetic acid solution were mixed at a mass ratio of 1:19 to obtain a first mixture, which was set aside. The additive was mixed with anhydrous ethanol at a mass ratio of 1:5 to obtain a second mixture. The first and second mixtures were stirred and mixed at 40°C, the pH was adjusted to 8.0, and the reaction was carried out for 2 hours. The mixture was centrifuged to obtain a filter residue, which was then dried. The dried filter residue was mixed with anhydrous ethanol at a mass ratio of 1:8, eugenol was added, and the mixture was reacted at 30°C for 6 hours. After centrifugation and drying, additive A was obtained. The mass concentration of the acetic acid solution was 1%, and the mass of eugenol was 20% of the mass of the filter residue.

[0024] Preparation of the reaction mixture: After crushing the pepper seeds, pass them through a 40-mesh sieve to obtain pepper seed powder. Transfer the pepper seed powder into a supercritical CO2 extraction vessel, add a 65% ethanol solution, and react at 25 MPa and 40℃ for 1 h. Collect the reaction solution and concentrate it under reduced pressure at 40℃ for 1 h to obtain the reaction mixture.

[0025] Preparation of composite powder: Cassava starch and anhydrous ethanol were mixed at a mass ratio of 1:4. The reactants and a 12% sodium hydroxide solution were added, and the mixture was reacted in a water bath at 15°C for 1.2 h. Then sodium chloroacetate was added, and the mixture was reacted at 50°C for 4 h. The pH was adjusted to 6.5 with 0.5 mol / L dilute hydrochloric acid. The residue was collected by filtration and dried to obtain the composite powder.

[0026] The sodium hydroxide solution comprises 20% of the cassava starch mass, the molar ratio of sodium chloroacetate to cassava starch is 0.2:1, and the reactant mass comprises 5% of the cassava starch mass. Preparation of Additive B: Hydroxyl-terminated polycaprolactone and epichlorohydrin were mixed at a mass ratio of 1:3, tetrabutylammonium bromide was added, and the mixture was reacted at 80℃ for 4 hours. After vacuum distillation for 1 hour, an intermediate product was obtained and set aside. The composite powder was mixed with deionized water at a mass ratio of 1:4 to obtain a suspension. Ammonium persulfate was added, and the mixture was stirred and activated at 70℃ for 20 minutes. The intermediate product was added dropwise, and the mixture was reacted for 3 hours. After centrifugation, washing, and drying, Additive B was obtained.

[0027] The mass of the tetrabutylammonium bromide is 0.5% of the mass of the hydroxyl-terminated polycaprolactone, the mass of the ammonium persulfate is 0.5% of the mass of the composite powder, and the mass of the intermediate product is 30% of the mass of the composite powder.

[0028] Raw material preparation: 40 parts polylactic acid, 20 parts polyadipic acid, 5 parts additive A, 3 parts additive B, 2 parts polyethylene glycol and 1 part polyethylene wax.

[0029] Preparation of environmentally friendly biodegradable antibacterial films: Step 1: Polylactic acid, polyadipic acid, additive A, additive B, polyethylene glycol and polyethylene wax are put into a high-speed mixer and mixed at 300 rpm for 10 minutes to obtain a premix. Step 2: Transfer the premixed material into a twin-screw extruder, melt-blend at 150°C, and then extrude and granulate to obtain film granules; Step 3: The film granules are formed at 160°C using a casting machine or blown film machine, and then cooled to obtain an environmentally friendly biodegradable antibacterial film. Example 2

[0030] Preparation of the additive: After drying the loofah sponge at 90℃ for 18h, it was transferred to a tube furnace and heated to 350℃ at a rate of 8℃ / min under a nitrogen atmosphere. After holding the temperature for 1.5h, potassium hydroxide was added, and the temperature was raised to 700℃ for 2.5h. After cooling, the reaction product was taken out and washed with 0.8mol / L hydrochloric acid solution until neutral, and then washed 4 times with deionized water. It was dried at 90℃ to obtain loofah sponge charcoal. The loofah sponge charcoal and tea polyphenol solution were mixed at a mass ratio of 1:8 and stirred at 30℃ and 350rpm for 18h. After filtration, the filter residue was dried at 60℃ for 10h to obtain the additive. The mass of potassium hydroxide was 3 times the mass of loofah sponge, and the mass concentration of tea polyphenol solution was 15%.

[0031] Preparation of modified chitosan: Chitosan and isopropanol were mixed at a mass ratio of 1:8. A 25% sodium hydroxide solution was added under nitrogen protection and the mixture was reacted at room temperature for 2 hours. Then, 2,3-epoxypropyltrimethylammonium chloride was added dropwise and the mixture was reacted at 70°C for 10 hours. The mixture was filtered, the residue was collected, and dried to obtain modified chitosan. The mass of the sodium hydroxide solution was 0.8 times the mass of the chitosan, and the molar ratio of 2,3-epoxypropyltrimethylammonium chloride to chitosan was 1.5:1.

[0032] Preparation of Additive A: Modified chitosan and acetic acid solution were mixed at a mass ratio of 1:36 to obtain a first mixture, which was set aside. The additive was mixed with anhydrous ethanol at a mass ratio of 1:8 to obtain a second mixture. The first and second mixtures were stirred and mixed at 50°C, the pH was adjusted to 8.5, and the reaction was carried out for 3 hours. The mixture was centrifuged to obtain a filter residue, which was then dried. The dried filter residue was mixed with anhydrous ethanol at a mass ratio of 1:10, eugenol was added, and the mixture was reacted at 40°C for 9 hours. After centrifugation and drying, additive A was obtained. The mass concentration of the acetic acid solution was 2%, and the mass of eugenol was 30% of the mass of the filter residue.

[0033] Preparation of the reaction mixture: The pepper seeds were crushed and passed through a 60-mesh sieve to obtain pepper seed powder. The pepper seed powder was transferred into a supercritical CO2 extraction vessel, and a 65% (v / v) ethanol solution was added. The mixture was reacted at 30 MPa and 45°C for 2 hours. The reaction solution was collected and concentrated under reduced pressure at 45°C for 2 hours to obtain the reaction mixture.

[0034] Preparation of composite powder: Cassava starch and anhydrous ethanol were mixed at a mass ratio of 1:6, reactants and 13% sodium hydroxide solution were added, and the mixture was reacted in a water bath at 20°C for 1.3 h. Then sodium chloroacetate was added, and the mixture was reacted at 60°C for 5 h. The pH was adjusted to 7.0 with 0.8 mol / L dilute hydrochloric acid, the residue was collected by filtration, and the residue was dried to obtain composite powder.

[0035] The sodium hydroxide solution comprises 30% of the cassava starch mass, the molar ratio of sodium chloroacetate to cassava starch is 0.3:1, and the reactant mass comprises 6.5% of the cassava starch mass. Preparation of Additive B: Hydroxyl-terminated polycaprolactone and epichlorohydrin were mixed at a mass ratio of 1:5, tetrabutylammonium bromide was added, and the mixture was reacted at 90℃ for 5 h. After vacuum distillation for 2 h, an intermediate product was obtained and set aside. The composite powder was mixed with deionized water at a mass ratio of 1:6 to obtain a suspension. Ammonium persulfate was added, and the mixture was stirred and activated at 80℃ for 30 min. The intermediate product was added dropwise, and the mixture was reacted for 4 h. After centrifugation, washing, and drying, Additive B was obtained.

[0036] The mass of the tetrabutylammonium bromide is 1% of the mass of the hydroxyl-terminated polycaprolactone, the mass of the ammonium persulfate is 1% of the mass of the composite powder, and the mass of the intermediate product is 40% of the mass of the composite powder.

[0037] Raw material preparation: 50 parts polylactic acid, 30 parts polyadipic acid, 10 parts additive A, 7 parts additive B, 4 parts polyethylene glycol and 3 parts polyethylene wax.

[0038] Preparation of environmentally friendly biodegradable antibacterial films: Step 1: Polylactic acid, polyadipic acid, additive A, additive B, polyethylene glycol and polyethylene wax are put into a high-speed mixer and mixed at 500 rpm for 15 minutes to obtain a premix. Step 2: Transfer the premixed material into a twin-screw extruder, melt-blend at 170°C, and then extrude and granulate to obtain film granules; Step 3: The film granules are formed at 180°C using a casting machine or blown film machine, and then cooled to obtain an environmentally friendly biodegradable antibacterial film. Example 3

[0039] Preparation of the additive: After drying the loofah sponge at 100℃ for 24h, it was transferred to a tube furnace and heated to 400℃ at a rate of 10℃ / min under a nitrogen atmosphere. After holding the temperature for 2h, potassium hydroxide was added, and the temperature was raised to 800℃ for 3h. After cooling, the reaction product was taken out and washed with 1mol / L hydrochloric acid solution until neutral, then washed 5 times with deionized water and dried at 100℃ to obtain loofah sponge charcoal. The loofah sponge charcoal and tea polyphenol solution were mixed at a mass ratio of 1:10 and stirred at 35℃ at a speed of 500rpm for 24h. After filtration, the filter residue was dried at 70℃ for 12h to obtain the additive. The mass of potassium hydroxide was 4 times the mass of loofah sponge, and the mass concentration of tea polyphenol solution was 20%.

[0040] Preparation of modified chitosan: Chitosan and isopropanol were mixed at a mass ratio of 1:10. A 30% sodium hydroxide solution was added under nitrogen protection and the mixture was reacted at room temperature for 3 hours. Then, 2,3-epoxypropyltrimethylammonium chloride was added dropwise and the mixture was reacted at 80°C for 12 hours. The mixture was filtered, the residue was collected, and dried to obtain modified chitosan. The mass of the sodium hydroxide solution was equal to the mass of the chitosan, and the molar ratio of 2,3-epoxypropyltrimethylammonium chloride to chitosan was 2:1.

[0041] Preparation of Additive A: Modified chitosan and acetic acid solution were mixed at a mass ratio of 1:49 to obtain a first mixture, which was set aside. The additive was mixed with anhydrous ethanol at a mass ratio of 1:10 to obtain a second mixture. The first and second mixtures were stirred and mixed at 60°C, the pH was adjusted to 9.0, and the reaction was carried out for 4 hours. The mixture was centrifuged to obtain a filter residue, which was dried. The dried filter residue was mixed with anhydrous ethanol at a mass ratio of 1:12, eugenol was added, and the mixture was reacted at 50°C for 12 hours. After centrifugation and drying, additive A was obtained. The mass concentration of the acetic acid solution was 3%, and the mass of eugenol was 40% of the mass of the filter residue.

[0042] Preparation of the reaction material: After crushing the pepper seeds, pass them through an 80-mesh sieve to obtain pepper seed powder. Transfer the pepper seed powder into a supercritical CO2 extraction vessel, add a 65% (v / v) ethanol solution, and react at 35 MPa and 50 °C for 3 h. Collect the reaction solution and concentrate it under reduced pressure at 50 °C for 3 h to obtain the reaction material.

[0043] Preparation of composite powder: Cassava starch and anhydrous ethanol were mixed at a mass ratio of 1:8, reactants and 15% sodium hydroxide solution were added, and the mixture was reacted in a water bath at 25°C for 1.5 h. Then sodium chloroacetate was added, and the mixture was reacted at 70°C for 6 h. The pH was adjusted to 7.0 with 1 mol / L dilute hydrochloric acid, the residue was collected by filtration, and the residue was dried to obtain composite powder.

[0044] The sodium hydroxide solution comprises 40% of the cassava starch mass, the molar ratio of sodium chloroacetate to cassava starch is 0.5:1, and the reactant mass comprises 8% of the cassava starch mass. Preparation of Additive B: Hydroxyl-terminated polycaprolactone and epichlorohydrin were mixed at a mass ratio of 1:6, tetrabutylammonium bromide was added, and the mixture was reacted at 100℃ for 6 h. After vacuum distillation for 3 h, an intermediate product was obtained and set aside. The composite powder was mixed with deionized water at a mass ratio of 1:9 to obtain a suspension. Ammonium persulfate was added, and the mixture was stirred and activated at 90℃ for 40 min. The intermediate product was added dropwise, and the mixture was reacted for 5 h. After centrifugation, washing, and drying, Additive B was obtained.

[0045] The mass of the tetrabutylammonium bromide is 2% of the mass of the hydroxyl-terminated polycaprolactone, the mass of the ammonium persulfate is 1.5% of the mass of the composite powder, and the mass of the intermediate product is 50% of the mass of the composite powder.

[0046] Preparation of raw materials: 60 parts polylactic acid, 40 parts polyadipic acid, 15 parts additive A, 10 parts additive B, 8 parts polyethylene glycol and 5 parts polyethylene wax.

[0047] Preparation of environmentally friendly biodegradable antibacterial films: Step 1: Polylactic acid, polyadipic acid, additive A, additive B, polyethylene glycol and polyethylene wax are put into a high-speed mixer and mixed at 800 rpm for 20 minutes to obtain a premix. Step 2: Transfer the premixed material into a twin-screw extruder, melt-blend at 190°C, and then extrude and granulate to obtain film granules; Step 3: The film granules are formed at 200°C using a casting machine or blown film machine, and then cooled to obtain an environmentally friendly biodegradable antibacterial film.

[0048] Comparative Example 1: The difference between this comparative example and Example 1 is that this comparative example does not contain additive A.

[0049] Comparative Example 2 differs from Example 1 in that it does not contain additive B.

[0050] Comparative Example 3 differs from Example 1 in that it does not contain additives A and B.

[0051] Performance testing: The environmentally friendly biodegradable antibacterial films prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to performance testing, and the test data are recorded in the table below: Table 1 Testing items Antibacterial rate (%) Staphylococcus aureus antibacterial rate (%) Antibacterial rate (%) Staphylococcus aureus antibacterial rate (%) Tensile strength (MPa) Biodegradation rate (%) Example 1 98.0 99.2 28.5 92.3 Example 2 99.1 99.4 29.1 93.0 Example 3 99.3 99.6 29.8 93.6 Comparative Example 1 83.2 84.1 21.3 84.2 Comparative Example 2 85.1 87.0 22.7 85.1 Comparative Example 3 65.1 68.4 19.6 81.2 In the performance testing, the antibacterial rate was determined according to GB / T 31402-2023, using Escherichia coli and Staphylococcus aureus as test bacteria to determine the antibacterial rate of the film; the tensile strength was determined according to GB / T 1040.3-2006; and the biodegradability was determined according to the national standard GB / T 19277.1-2025, measuring the biodegradability of the film within 60 days.

[0052] The data obtained from the performance tests show that the antibacterial rate, tensile strength, and biodegradation rate of the environmentally friendly biodegradable antibacterial films prepared in Examples 1-3 are significantly higher than those in Comparative Examples 1-3. This indicates that additive A, through the synergistic effect of the modified chitosan's cationic structure and the tea polyphenols and eugenol loaded on the loofah charcoal, constructs a multi-layered antibacterial network within the film. The modified chitosan, with its positive charge, disrupts the integrity of bacterial cell membranes, while the porous structure of the loofah charcoal enables the adsorption and targeted sustained release of antibacterial active ingredients. Together, they enhance the broad-spectrum antibacterial efficacy of the film. Furthermore, the modified chitosan and the loofah charcoal... The charcoal effectively improved the interfacial compatibility with the polylactic acid matrix, avoiding the decline in mechanical properties caused by phase separation. Compared with Comparative Example 1, which lacked additive A, the antibacterial rate and tensile strength of the examples showed significant advantages. After the absence of additive A, Comparative Example 1 lost the membrane-destructive effect of cationic chitosan and the adsorption-directed release function of the charcoal carrier, resulting in a significant decrease in the inhibitory ability against both bacteria. Its tensile strength and biodegradation rate also decreased significantly. This indicates that additive A not only plays an important antibacterial role in the film system, but also plays a role in strengthening and toughening by improving interfacial compatibility.

[0053] Furthermore, additive B was prepared by modifying cassava starch with active ingredients from Sichuan pepper seeds using supercritical extraction to obtain a composite powder. After grafting and cross-linking with terminal hydroxyl polycaprolactone, a flexible cross-linked network structure was formed within the polyadic acid matrix. This structure can effectively dissipate energy through the orientation and slippage of molecular chains under external force, thus significantly improving the toughness of the film. Simultaneously, the active ingredients from Sichuan pepper seeds, as natural antibacterial substances, complement the antibacterial system in additive A, further prolonging the antibacterial effect of the film. In contrast, in Comparative Example 2, the absence of additive B resulted in a decrease in both the tensile strength and antibacterial rate of the film, and a lower biodegradability. In the examples, since Comparative Example 2 retained the rapid bactericidal ability of Additive A, its test data were slightly higher than those of Comparative Example 1. In Comparative Example 3, which lacked both additives, the performance indicators of the film were reduced to the lowest level, fully verifying the synergistic enhancement effect of Additive A and Additive B in antibacterial, mechanical and degradation performance. When the two work together, they can form a uniform interpenetrating network structure inside the film, which significantly improves the antibacterial rate and antimicrobial durability on the one hand, and significantly improves the mechanical strength and thermal stability of the matrix on the other hand. At the same time, they synergistically regulate the degradation rate, so that the film can be degraded under the premise of meeting the performance requirements.

[0054] By comparing and analyzing the relevant data in the table, it can be seen that the environmentally friendly biodegradable antibacterial film prepared by this invention not only has good biodegradability but also long-lasting antibacterial properties. This indicates that the environmentally friendly biodegradable antibacterial film provided by this invention has a broader market prospect and is more suitable for promotion.

[0055] 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.

[0056] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. An environmentally friendly degradable antibacterial film, characterized in that, It includes the following raw materials by weight: 40-60 parts polylactic acid, 20-40 parts polyadipic acid, 5-15 parts additive A, 3-10 parts additive B, 2-8 parts polyethylene glycol and 1-5 parts polyethylene wax; The raw materials for additive A include modified chitosan, acetic acid solution, additives, and eugenol; The raw materials for additive B include hydroxyl-terminated polycaprolactone, epichlorohydrin, tetrabutylammonium bromide, composite powder, and ammonium persulfate.

2. The environment-friendly degradable antibacterial film according to claim 1, characterized in that, Additive A is prepared by the following method: Modified chitosan and acetic acid solution are mixed at a mass ratio of 1:(19-49) to obtain a first mixture, which is set aside for later use. The additive is mixed with anhydrous ethanol at a mass ratio of 1:(5-10) to obtain a second mixture. The first mixture and the second mixture are stirred and mixed at 40-60℃, the pH is adjusted to 8.0-9.0, and the reaction is carried out for 2-4 hours. The residue is obtained by centrifugation and dried. The dried residue is mixed with anhydrous ethanol at a mass ratio of 1:(8-12), eugenol is added, and the reaction is carried out at 30-50℃ for 6-12 hours. After centrifugation and drying, additive A is obtained. The mass concentration of the acetic acid solution is 1-3%, and the mass of eugenol is 20-40% of the mass of the residue.

3. The environment-friendly degradable antibacterial film according to claim 2, characterized in that, The additive is prepared by the following method: Loofah sponge is dried at 80-100℃ for 12-24 hours, then transferred to a tube furnace and heated to 300-400℃ at a rate of 5-10℃ / min under a nitrogen atmosphere. The temperature is maintained for 1-2 hours, then potassium hydroxide is added, and the temperature is raised to 600-800℃ for 2-3 hours. After cooling, the reaction product is removed and washed with 0.5-1 mol / L hydrochloric acid solution until neutral, then washed with deionized water. The mixture is dried 3-5 times at 80-100℃ to obtain charcoal from the loofah sponge. The charcoal sponge and tea polyphenol solution are mixed at a mass ratio of 1:(5-10) and stirred at 200-500 rpm for 12-24 hours at 25-35℃. The mixture is then filtered, and the filter residue is dried at 50-70℃ for 8-12 hours to obtain the additive. The mass of potassium hydroxide is 2-4 times the mass of the loofah sponge, and the mass concentration of the tea polyphenol solution is 10-20%.

4. The environment-friendly degradable antibacterial film according to claim 2, characterized in that, The modified chitosan is prepared by the following method: chitosan and isopropanol are mixed at a mass ratio of 1:(5-10), and a sodium hydroxide solution with a mass concentration of 20-30% is added under nitrogen protection. The mixture is reacted at room temperature for 1-3 hours, and then 2,3-epoxypropyltrimethylammonium chloride is added dropwise. The mixture is reacted at 60-80°C for 8-12 hours, filtered, the filter residue is collected, and dried to obtain the modified chitosan. The mass of the sodium hydroxide solution is 0.5-1 times the mass of the chitosan, and the molar ratio of 2,3-epoxypropyltrimethylammonium chloride to chitosan is (1-2):

1.

5. The environment-friendly degradable antibacterial film according to claim 1, characterized in that, Additive B is prepared by the following method: hydroxyl-terminated polycaprolactone and epichlorohydrin are mixed at a mass ratio of 1:(3-6), tetrabutylammonium bromide is added, and the mixture is reacted at 80-100℃ for 4-6 hours. The mixture is then distilled under reduced pressure for 1-3 hours to obtain an intermediate product, which is set aside for later use. The composite powder is mixed with deionized water at a mass ratio of 1:(4-9) to obtain a suspension. Ammonium persulfate is added, and the mixture is stirred and activated at 70-90℃ for 20-40 minutes. The intermediate product is added dropwise, and the mixture is reacted for 3-5 hours. After centrifugation, washing, and drying, additive B is obtained.

6. The environment-friendly degradable antibacterial film according to claim 5, characterized in that, The composite powder is prepared by the following method: cassava starch and anhydrous ethanol are mixed at a mass ratio of 1:(4-8), reactants and a 12-15% sodium hydroxide solution are added, and the mixture is reacted in a water bath at 15-25℃ for 1.2-1.5 hours. Then sodium chloroacetate is added, and the mixture is reacted at 50-70℃ for 4-6 hours. The pH is adjusted to 6.5-7.0 with 0.5-1 mol / L dilute hydrochloric acid, the residue is collected by filtration, and the residue is dried to obtain the composite powder.

7. The environment-friendly degradable antibacterial film according to claim 6, characterized in that, The reaction mixture is prepared by the following method: Sichuan pepper seeds are crushed and passed through a 40-80 mesh sieve to obtain Sichuan pepper seed powder. The Sichuan pepper seed powder is transferred into a supercritical CO2 extraction vessel, and a 65% (v / v) ethanol solution is added. The mixture is reacted at 25-35 MPa and 40-50 °C for 1-3 hours. The reaction solution is collected and concentrated under reduced pressure at 40-50 °C for 1-3 hours to obtain the reaction mixture.

8. The environmentally friendly biodegradable antibacterial film according to claim 5, characterized in that, The mass of the tetrabutylammonium bromide is 0.5-2% of the mass of the hydroxyl-terminated polycaprolactone, the mass of the ammonium persulfate is 0.5-1.5% of the mass of the composite powder, and the mass of the intermediate product is 30-50% of the mass of the composite powder.

9. The environmentally friendly biodegradable antibacterial film according to claim 6, characterized in that, The sodium hydroxide solution has a mass of 20-40% of the cassava starch mass, the molar ratio of sodium chloroacetate to cassava starch is (0.2-0.5):1, and the mass of the reactant is 5-8% of the cassava starch mass.

10. The method for preparing the environmentally friendly biodegradable antibacterial film according to claims 1-9, characterized in that, Includes the following steps: Step 1: Add polylactic acid, polyadipic acid, additive A, additive B, polyethylene glycol and polyethylene wax into a high-speed mixer and mix for 10-20 minutes at a speed of 300-800 rpm to obtain a premix. Step 2: Transfer the premixed material into a twin-screw extruder, melt-blend at 150-190℃, and then extrude and granulate to obtain film granules; Step 3: The film granules are formed at 160-200℃ using a casting machine or blown film machine, and then cooled to obtain an environmentally friendly biodegradable antibacterial film.

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