High-barrier environment-friendly packaging film with antibacterial function

Abstract

The application relates to the technical field of high-barrier environment-friendly packaging films, and discloses a high-barrier environment-friendly packaging film with antibacterial function, which comprises, from bottom to top, a base layer, a nano-composite barrier layer, a bio-based functional layer and an outer protective layer, and the layers are tightly attached through a coated starch-based adhesive. The high-barrier environment-friendly packaging film with antibacterial function is prepared by using polyhydroxyaliphatic ester in the base layer film, biodegradable polycaprolactone in the nano-composite barrier layer film and konjac glucomannan in the bio-functional layer film, all of which have good biodegradability and can be decomposed into carbon dioxide and water by microorganisms in various environments, and have excellent flexibility and processing performance, can adapt to different packaging requirements, provide basic flexibility and structural support for the overall packaging film and green environmental protection effect, and the procyanidins arranged in the outer protective layer film provide stronger antibacterial performance and water solubility for the overall packaging film.

Description

Technical Field

[0001] This invention relates to the field of high-barrier environmentally friendly packaging film technology, specifically a high-barrier environmentally friendly packaging film with antibacterial function. Background Technology

[0002] Currently, packaging films used for cosmetics, alcoholic beverages, and similar products are generally made by laminating PE film with self-adhesive labels. However, most PE films on the market have poor barrier properties, offering inadequate waterproofing and oil resistance, requiring special treatment. Furthermore, commonly used solvent-based adhesives, whether oil-based or water-based transfer adhesives, must be diluted with a thinner before use.

[0003] Diluents contain a large number of harmful ingredients, which directly contaminate cosmetics and alcoholic beverages. Furthermore, during the production process, the harmful ingredients in the diluent will evaporate and be released into the atmosphere, causing serious environmental pollution and greatly increasing the production cost of the products.

[0004] Therefore, the present invention provides a high-barrier environmentally friendly packaging film with antibacterial function to solve the above-mentioned problems. Summary of the Invention

[0005] Technical problems to be solved

[0006] To address the shortcomings of existing technologies, this invention provides a high-barrier composite packaging film with antibacterial function, which has the following advantages and solves the aforementioned problems.

[0007] (II) Technical Solution

[0008] To achieve the above objectives, the present invention provides the following technical solution: a high-barrier environmentally friendly packaging film with antibacterial function, comprising, from bottom to top, a base layer, a nano-composite barrier layer, a bio-based functional layer and an outer protective layer, wherein each layer is tightly bonded together by a coated starch-based adhesive.

[0009] Preferably, the base layer comprises the following raw materials in the following weight ratios: 850-900 parts of polyhydroxyalkanoate, 100-150 parts of composite reinforcing material, and 3-7 parts of natural antioxidant, wherein the natural antioxidant is ferulic acid, and the composite reinforcing material is a composite reinforcing material made of nanocellulose whiskers and graphene.

[0010] Preferably, the nanocomposite barrier layer comprises the following raw materials in the following weight ratios: 750-850 parts polycaprolactone, 120-150 parts antibacterial barrier particles, 5-10 parts environmentally friendly dispersant, and 30-70 parts bio-based plasticizer. The bio-based plasticizer is triethyl citrate, the environmentally friendly dispersant is soybean lecithin, and the antibacterial barrier particles are antibacterial barrier particles made of nano zinc oxide and silicon dioxide composite, with a particle size of 30-60 nm.

[0011] Preferably, the bio-based functional layer comprises the following raw materials in the indicated weight ratios: 450-500 parts of konjac glucomannan, 20-50 parts of a composite antibacterial agent, 20-40 parts of a natural moisturizer, and 10-30 parts of a bio-based crosslinking agent. The composite antibacterial agent is a composite antibacterial agent made of lysozyme and chitosan quaternary ammonium salt, the natural moisturizer is sodium hyaluronate, and the bio-based crosslinking agent is tannic acid.

[0012] Preferably, the outer protective layer comprises the following raw materials in the following weight ratios: 900-990 parts of polylactic acid-glycolic acid copolymer and 4-10 parts of natural anti-aging agent, wherein the natural anti-aging agent is proanthocyanidins.

[0013] Preferably, the preparation steps of the base layer are as follows:

[0014] First, prepare the composite reinforcing material: add nanocellulose whiskers and graphene to anhydrous ethanol and ultrasonically disperse for 30-60 minutes to make the nanocellulose whiskers and graphene uniformly dispersed in the ethanol solution to form a stable suspension. The ultrasonic frequency is set to 40-60kHz and the power is 200-400W.

[0015] The dried polyhydroxy fatty acid ester particles were added to a high-speed mixer, and then the nanocellulose whisker-graphene suspension was slowly poured in. Ferulic acid was added at the same time. The speed of the high-speed mixer was set to 800-1000 r / min and the mixing time was 15-20 minutes to ensure that the components were fully mixed.

[0016] The mixture is then added to a twin-screw extruder, and the extruder temperature parameters are set as follows: Zone 1 temperature 130-140℃, Zone 2 temperature 140-150℃, Zone 3 temperature 150-160℃, Zone 4 temperature 160-170℃, Die temperature 170-180℃, and screw speed controlled at 180-220 r / min. After the material is melted and blended in the extruder, it is extruded through a T-die and cooled and shaped by cooling rollers to obtain the base film.

[0017] Preferably, the preparation steps of the nanocomposite barrier layer are as follows:

[0018] First, the antibacterial barrier particles are prepared: the composite particles are added to deionized water and ultrasonically dispersed for 40-70 minutes at an ultrasonic frequency of 50-70kHz and a power of 250-450W to ensure uniform dispersion of the particles. Then, the water is removed by centrifugation and dried at 60-70℃ for 2-3 hours.

[0019] The dried polycaprolactone granules, pretreated nano-zinc oxide-silica composite particles, triethyl citrate, and soybean lecithin were sequentially added to a high-speed mixer. After the components were fully mixed, the mixture was fed into a single-screw extruder. The extruder temperatures were set as follows: feeding section temperature 140-150℃, compression section temperature 150-160℃, metering section temperature 160-170℃, and die temperature 170-180℃. The screw speed was controlled at 150-180 r / min. After extrusion, the material was cast into a film using a casting machine. The casting roller temperature was controlled at 25-30℃ to obtain a nano-composite barrier film.

[0020] Preferably, the preparation steps of the bio-based functional layer are as follows:

[0021] First, prepare a composite antibacterial agent solution: dissolve lysozyme and chitosan quaternary ammonium salt in deionized water to prepare a solution with a mass fraction of 2%-3%, then mix the two solutions at a volume ratio of 1:1 and stir evenly.

[0022] Then, slowly add konjac glucomannan to deionized water and stir to dissolve at 60-70℃. The mass ratio of konjac glucomannan to water is 1:10-1:15. The stirring speed is 200-300 r / min and the stirring time is 2-3 hours until a homogeneous solution is formed.

[0023] Next, konjac glucomannan solution, lysozyme-chitosan quaternary ammonium salt composite antibacterial agent solution, sodium hyaluronate and tannic acid are added to the reaction vessel and stirred at 50-60℃ for 1-2 hours at a stirring speed of 150-250 r / min to form a uniform bio-based functional layer solution.

[0024] Finally, the bio-based functional layer solution is uniformly coated onto a flat substrate using a blade coating method. The coated substrate is then placed in a drying oven and dried at 40-50°C for 12-24 hours to allow the solvent to fully evaporate and form a bio-based functional layer film.

[0025] Preferably, the preparation steps of the outer protective layer are as follows: adding polylactic acid-glycolic acid copolymer particles into dichloromethane, wherein the mass ratio of polylactic acid-glycolic acid copolymer to dichloromethane is 1:5-1:8, stirring and dissolving at room temperature, stirring speed 150-200 r / min, stirring time 3-4 hours, until a uniform polylactic acid-glycolic acid copolymer solution is formed;

[0026] Proanthocyanidins were added to a polylactic acid-glycolic acid copolymer solution and stirred until homogeneous at a stirring speed of 100-150 r / min for 30-40 minutes. The mixture was then uniformly coated onto a smooth polyester film and dried naturally at room temperature for 2-3 hours using a casting method to allow some of the dichloromethane to evaporate. The film was then placed in a vacuum drying oven and dried at 40-50℃ and a vacuum of -0.08 to -0.09 MPa for 8-10 hours to obtain an outer protective layer film with a thickness of 10-12 μm.

[0027] (III) Beneficial Effects

[0028] Compared with the prior art, the present invention provides a high-barrier environmentally friendly packaging film with antibacterial function, which has the following beneficial effects:

[0029] 1. This high-barrier environmentally friendly packaging film with antibacterial function utilizes polyhydroxy fatty acid esters in the base film, biodegradable polycaprolactone in the nanocomposite barrier layer film, konjac glucomannan in the biofunctional layer film, and polylactic acid-glycolic acid copolymer in the outer protective layer film. All of these materials have good biodegradability and can be decomposed into carbon dioxide and water by microorganisms in various environments. They also have excellent flexibility and processing performance, which can adapt to different packaging needs and provide basic flexibility, structural support and green environmental protection effect for the overall packaging film.

[0030] 2. This high-barrier environmentally friendly packaging film with antibacterial function provides stronger antibacterial properties and water solubility to the entire packaging film through the lysozyme-chitosan quaternary ammonium salt composite antibacterial agent set in the biofunctional layer film and the proanthocyanidins in the outer protective layer film. It can effectively inhibit a variety of bacteria and fungi, protect the outer surface of the packaging film from microbial erosion, and its natural source ensures that it will not pollute the environment after use, which is in line with the concept of environmentally friendly packaging. Detailed Implementation

[0031] 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] Example 1:

[0033] A high-barrier environmentally friendly packaging film with antibacterial function includes, from bottom to top, a base layer, a nanocomposite barrier layer, a bio-based functional layer and an outer protective layer, with each layer tightly bonded together by a coated starch-based adhesive.

[0034] The base layer comprises the following raw materials in the following weight proportions: 850 parts of polyhydroxy fatty acid ester, 100 parts of composite reinforcing material, and 3 parts of natural antioxidant. The natural antioxidant is ferulic acid, and the composite reinforcing material is a composite reinforcing material made of nano-cellulose whiskers and graphene.

[0035] The preparation steps for the base layer are as follows:

[0036] First, the composite reinforcing material was prepared: nanocellulose whiskers and graphene were added to anhydrous ethanol and ultrasonically dispersed for 30 minutes to make the nanocellulose whiskers and graphene uniformly dispersed in the ethanol solution to form a stable suspension. The ultrasonic frequency was set to 40kHz and the power was 200W.

[0037] The dried polyhydroxy fatty acid ester particles were added to a high-speed mixer, and then the nanocellulose whisker-graphene suspension was slowly poured in. Ferulic acid was added at the same time. The speed of the high-speed mixer was set to 800 r / min and the mixing time was 15 minutes to ensure that the components were fully mixed.

[0038] The mixture is then added to a twin-screw extruder, and the extruder temperature parameters are set as follows: Zone 1 temperature 130℃, Zone 2 temperature 140℃, Zone 3 temperature 150℃, Zone 4 temperature 160℃, Die temperature 170℃, and screw speed controlled at 180 r / min. After the material is melted and blended in the extruder, it is extruded through a T-die and cooled and shaped by a cooling roller to obtain the base film.

[0039] The nanocomposite barrier layer comprises the following raw materials in the following weight ratios: 750 parts polycaprolactone, 120 parts antibacterial barrier particles, 5 parts environmentally friendly dispersant, and 30 parts bio-based plasticizer. The bio-based plasticizer is triethyl citrate, the environmentally friendly dispersant is soybean lecithin, and the antibacterial barrier particles are antibacterial barrier particles made of nano zinc oxide and silicon dioxide composite, with a particle size of 30 nm.

[0040] The preparation steps of the nanocomposite barrier layer are as follows:

[0041] First, the antibacterial barrier particles were prepared: the composite particles were added to deionized water and ultrasonically dispersed for 40 minutes at a frequency of 50 kHz and a power of 250 W to ensure uniform dispersion of the particles. Then, the water was removed by centrifugation and dried at 60°C for 2 hours.

[0042] The dried polycaprolactone granules, pretreated nano-zinc oxide-silica composite particles, triethyl citrate, and soybean lecithin were sequentially added to a high-speed mixer. After the components were fully mixed, the mixture was added to a single-screw extruder. The extruder temperatures were set as follows: feeding section temperature 140℃, compression section temperature 150℃, metering section temperature 160℃, and die temperature 170℃. The screw speed was controlled at 150 r / min. After extrusion, the material was cast into a film using a casting machine. The casting roller temperature was controlled at 25℃ to obtain a nano-composite barrier film.

[0043] The bio-based functional layer comprises the following raw materials in the following weight proportions: 450 parts konjac glucomannan, 20 parts compound antibacterial agent, 20 parts natural moisturizer, and 10 parts bio-based cross-linking agent. The compound antibacterial agent is a compound antibacterial agent made of lysozyme and chitosan quaternary ammonium salt, the natural moisturizer is sodium hyaluronate, and the bio-based cross-linking agent is tannic acid.

[0044] The preparation steps of the bio-based functional layer are as follows:

[0045] First, prepare a composite antibacterial agent solution: dissolve lysozyme and chitosan quaternary ammonium salt in deionized water to prepare a 2% mass fraction solution. Then, mix the two solutions in a 1:1 volume ratio and stir until homogeneous.

[0046] Then, konjac glucomannan was slowly added to deionized water and stirred at 60°C to dissolve. The mass ratio of konjac glucomannan to water was 1:10. The stirring speed was 200 r / min and the stirring time was 2 hours until a homogeneous solution was formed.

[0047] Next, konjac glucomannan solution, lysozyme-chitosan quaternary ammonium salt composite antibacterial agent solution, sodium hyaluronate and tannic acid were added to the reaction vessel and stirred at 50°C for 1 hour at a stirring speed of 150 r / min to form a uniform bio-based functional layer solution.

[0048] Finally, the bio-based functional layer solution was uniformly coated onto a flat substrate using a scraping method. The coated substrate was then placed in a drying oven and dried at 40°C for 12 hours to allow the solvent to fully evaporate and form a bio-based functional layer film.

[0049] The outer protective layer comprises the following raw materials in parts by weight: 900 parts of polylactic acid-glycolic acid copolymer and 4 parts of natural anti-aging agent, the natural anti-aging agent being proanthocyanidins;

[0050] The preparation steps of the outer protective layer are as follows: polylactic acid-glycolic acid copolymer particles are added to dichloromethane, the mass ratio of polylactic acid-glycolic acid copolymer to dichloromethane is 1:5, and the mixture is stirred and dissolved at room temperature at a stirring speed of 150 r / min for 3 hours until a uniform polylactic acid-glycolic acid copolymer solution is formed.

[0051] Proanthocyanidins were added to a polylactic acid-glycolic acid copolymer solution and stirred until homogeneous at a stirring speed of 100 r / min for 30 minutes. The mixture was then uniformly coated onto a smooth polyester film and dried naturally at room temperature for 2 hours using a casting method to allow some of the dichloromethane to evaporate. The film was then placed in a vacuum drying oven and dried at 40°C and a vacuum of -0.08 MPa for 8 hours to obtain an outer protective layer film with a thickness of 10 μm.

[0052] Example 2:

[0053] A high-barrier environmentally friendly packaging film with antibacterial function includes, from bottom to top, a base layer, a nanocomposite barrier layer, a bio-based functional layer and an outer protective layer, with each layer tightly bonded together by a coated starch-based adhesive.

[0054] The base layer comprises the following raw materials in the following weight proportions: 900 parts of polyhydroxy fatty acid ester, 150 parts of composite reinforcing material, and 7 parts of natural antioxidant. The natural antioxidant is ferulic acid, and the composite reinforcing material is a composite reinforcing material made of nano-cellulose whiskers and graphene.

[0055] The preparation steps for the base layer are as follows:

[0056] First, the composite reinforcing material was prepared: nanocellulose whiskers and graphene were added to anhydrous ethanol and ultrasonically dispersed for 60 minutes to make the nanocellulose whiskers and graphene uniformly dispersed in the ethanol solution to form a stable suspension. The ultrasonic frequency was set to 60kHz and the power was 400W.

[0057] The dried polyhydroxy fatty acid ester particles were added to a high-speed mixer, and then the nanocellulose whisker-graphene suspension was slowly poured in. Ferulic acid was added at the same time. The speed of the high-speed mixer was set to 1000 r / min and the mixing time was 20 minutes to ensure that all components were fully mixed.

[0058] The mixture is then added to a twin-screw extruder, and the extruder temperature parameters are set as follows: Zone 1 temperature 140℃, Zone 2 temperature 150℃, Zone 3 temperature 160℃, Zone 4 temperature 170℃, Die temperature 180℃, and screw speed controlled at 220 r / min. After the material is melted and blended in the extruder, it is extruded through a T-die and cooled and shaped by a cooling roller to obtain the base film.

[0059] The nanocomposite barrier layer comprises the following raw materials in the following weight ratios: 850 parts polycaprolactone, 150 parts antibacterial barrier particles, 10 parts environmentally friendly dispersant, and 70 parts bio-based plasticizer. The bio-based plasticizer is triethyl citrate, the environmentally friendly dispersant is soybean lecithin, and the antibacterial barrier particles are antibacterial barrier particles made of nano zinc oxide and silicon dioxide composite, with a particle size of 60 nm.

[0060] The preparation steps of the nanocomposite barrier layer are as follows:

[0061] First, the antibacterial barrier particles were prepared: the composite particles were added to deionized water and ultrasonically dispersed for 70 minutes at a frequency of 70 kHz and a power of 450 W to ensure uniform dispersion of the particles. Then, the water was removed by centrifugation and dried at 70°C for 3 hours.

[0062] The dried polycaprolactone granules, pretreated nano-zinc oxide-silica composite particles, triethyl citrate, and soybean lecithin were sequentially added to a high-speed mixer. After the components were fully mixed, the mixture was added to a single-screw extruder. The extruder temperatures were set as follows: feeding section temperature 150℃, compression section temperature 160℃, metering section temperature 170℃, and die temperature 180℃. The screw speed was controlled at 180 r / min. After extrusion, the material was cast into a film using a casting machine. The casting roller temperature was controlled at 30℃ to obtain a nano-composite barrier film.

[0063] The bio-based functional layer comprises the following raw materials in the following weight proportions: 500 parts konjac glucomannan, 50 parts compound antibacterial agent, 40 parts natural moisturizer, and 30 parts bio-based cross-linking agent. The compound antibacterial agent is a compound antibacterial agent made of lysozyme and chitosan quaternary ammonium salt, the natural moisturizer is sodium hyaluronate, and the bio-based cross-linking agent is tannic acid.

[0064] The preparation steps of the bio-based functional layer are as follows:

[0065] First, prepare a composite antibacterial agent solution: dissolve lysozyme and chitosan quaternary ammonium salt in deionized water to prepare a 3% mass fraction solution. Then, mix the two solutions in a 1:1 volume ratio and stir until homogeneous.

[0066] Then, konjac glucomannan was slowly added to deionized water and stirred at 70°C to dissolve. The mass ratio of konjac glucomannan to water was 1:15. The stirring speed was 300 r / min and the stirring time was 3 hours until a homogeneous solution was formed.

[0067] Next, konjac glucomannan solution, lysozyme-chitosan quaternary ammonium salt composite antibacterial agent solution, sodium hyaluronate and tannic acid were added to the reaction vessel and stirred at 60°C for 2 hours at a stirring speed of 250 r / min to form a uniform bio-based functional layer solution.

[0068] Finally, the bio-based functional layer solution was uniformly coated onto a flat substrate using a scraping method. The coated substrate was then placed in a drying oven and dried at 50°C for 24 hours to allow the solvent to fully evaporate and form a bio-based functional layer film.

[0069] The outer protective layer comprises the following raw materials in parts by weight: 990 parts of polylactic acid-glycolic acid copolymer and 10 parts of natural anti-aging agent, the natural anti-aging agent being proanthocyanidins;

[0070] The preparation steps of the outer protective layer are as follows: polylactic acid-glycolic acid copolymer particles are added to dichloromethane, the mass ratio of polylactic acid-glycolic acid copolymer to dichloromethane is 1:8, and the mixture is stirred and dissolved at room temperature at a stirring speed of 200 r / min for 4 hours until a uniform polylactic acid-glycolic acid copolymer solution is formed.

[0071] Proanthocyanidins were added to a polylactic acid-glycolic acid copolymer solution and stirred until homogeneous at a stirring speed of 150 r / min for 40 minutes. The mixture was then uniformly coated onto a smooth polyester film and dried naturally at room temperature for 3 hours using a casting method to allow some of the dichloromethane to evaporate. The film was then placed in a vacuum drying oven and dried at 50°C and a vacuum of -0.09 MPa for 10 hours to obtain an outer protective layer film with a thickness of 12 μm.

[0072] Example 3:

[0073] A high-barrier environmentally friendly packaging film with antibacterial function includes, from bottom to top, a base layer, a nanocomposite barrier layer, a bio-based functional layer and an outer protective layer, with each layer tightly bonded together by a coated starch-based adhesive.

[0074] The base layer comprises the following raw materials in the following weight proportions: 850 parts of polyhydroxy fatty acid ester, 100 parts of composite reinforcing material, and 3 parts of natural antioxidant. The natural antioxidant is ferulic acid, and the composite reinforcing material is a composite reinforcing material made of nano-cellulose whiskers and graphene.

[0075] The preparation steps for the base layer are as follows:

[0076] First, the composite reinforcing material was prepared: nanocellulose whiskers and graphene were added to anhydrous ethanol and ultrasonically dispersed for 30 minutes to make the nanocellulose whiskers and graphene uniformly dispersed in the ethanol solution to form a stable suspension. The ultrasonic frequency was set to 40kHz and the power was 200W.

[0077] The dried polyhydroxy fatty acid ester particles were added to a high-speed mixer, and then the nanocellulose whisker-graphene suspension was slowly poured in. Ferulic acid was added at the same time. The speed of the high-speed mixer was set to 800 r / min and the mixing time was 15 minutes to ensure that the components were fully mixed.

[0078] The mixture is then added to a twin-screw extruder, and the extruder temperature parameters are set as follows: Zone 1 temperature 130℃, Zone 2 temperature 140℃, Zone 3 temperature 150℃, Zone 4 temperature 160℃, Die temperature 170℃, and screw speed controlled at 180 r / min. After the material is melted and blended in the extruder, it is extruded through a T-die and cooled and shaped by a cooling roller to obtain the base film.

[0079] The nanocomposite barrier layer comprises the following raw materials in the following weight ratios: 850 parts polycaprolactone, 150 parts antibacterial barrier particles, 10 parts environmentally friendly dispersant, and 70 parts bio-based plasticizer. The bio-based plasticizer is triethyl citrate, the environmentally friendly dispersant is soybean lecithin, and the antibacterial barrier particles are antibacterial barrier particles made of nano zinc oxide and silicon dioxide composite, with a particle size of 60 nm.

[0080] The preparation steps of the nanocomposite barrier layer are as follows:

[0081] First, the antibacterial barrier particles were prepared: the composite particles were added to deionized water and ultrasonically dispersed for 70 minutes at a frequency of 70 kHz and a power of 450 W to ensure uniform dispersion of the particles. Then, the water was removed by centrifugation and dried at 70°C for 3 hours.

[0082] The dried polycaprolactone granules, pretreated nano-zinc oxide-silica composite particles, triethyl citrate, and soybean lecithin were sequentially added to a high-speed mixer. After the components were fully mixed, the mixture was added to a single-screw extruder. The extruder temperatures were set as follows: feeding section temperature 150℃, compression section temperature 160℃, metering section temperature 170℃, and die temperature 180℃. The screw speed was controlled at 180 r / min. After extrusion, the material was cast into a film using a casting machine. The casting roller temperature was controlled at 30℃ to obtain a nano-composite barrier film.

[0083] The bio-based functional layer comprises the following raw materials in the following weight proportions: 500 parts konjac glucomannan, 50 parts compound antibacterial agent, 40 parts natural moisturizer, and 30 parts bio-based cross-linking agent. The compound antibacterial agent is a compound antibacterial agent made of lysozyme and chitosan quaternary ammonium salt, the natural moisturizer is sodium hyaluronate, and the bio-based cross-linking agent is tannic acid.

[0084] The preparation steps of the bio-based functional layer are as follows:

[0085] First, prepare a composite antibacterial agent solution: dissolve lysozyme and chitosan quaternary ammonium salt in deionized water to prepare a 3% mass fraction solution. Then, mix the two solutions in a 1:1 volume ratio and stir until homogeneous.

[0086] Then, konjac glucomannan was slowly added to deionized water and stirred at 70°C to dissolve. The mass ratio of konjac glucomannan to water was 1:15. The stirring speed was 300 r / min and the stirring time was 3 hours until a homogeneous solution was formed.

[0087] Next, konjac glucomannan solution, lysozyme-chitosan quaternary ammonium salt composite antibacterial agent solution, sodium hyaluronate and tannic acid were added to the reaction vessel and stirred at 60°C for 2 hours at a stirring speed of 250 r / min to form a uniform bio-based functional layer solution.

[0088] Finally, the bio-based functional layer solution was uniformly coated onto a flat substrate using a scraping method. The coated substrate was then placed in a drying oven and dried at 50°C for 24 hours to allow the solvent to fully evaporate and form a bio-based functional layer film.

[0089] The outer protective layer comprises the following raw materials in parts by weight: 900 parts of polylactic acid-glycolic acid copolymer and 4 parts of natural anti-aging agent, the natural anti-aging agent being proanthocyanidins;

[0090] The preparation steps of the outer protective layer are as follows: polylactic acid-glycolic acid copolymer particles are added to dichloromethane, the mass ratio of polylactic acid-glycolic acid copolymer to dichloromethane is 1:5, and the mixture is stirred and dissolved at room temperature at a stirring speed of 150 r / min for 3 hours until a uniform polylactic acid-glycolic acid copolymer solution is formed.

[0091] Proanthocyanidins were added to a polylactic acid-glycolic acid copolymer solution and stirred until homogeneous at a stirring speed of 100 r / min for 30 minutes. The mixture was then uniformly coated onto a smooth polyester film and dried naturally at room temperature for 2 hours using a casting method to allow some of the dichloromethane to evaporate. The film was then placed in a vacuum drying oven and dried at 40°C and a vacuum of -0.08 MPa for 8 hours to obtain an outer protective layer film with a thickness of 10 μm.

[0092] The beneficial effects of this invention are as follows: This high-barrier environmentally friendly packaging film with antibacterial function utilizes polyhydroxy fatty acid esters in the base film, biodegradable polycaprolactone in the nanocomposite barrier layer film, konjac glucomannan in the biofunctional layer film, and polylactic acid-glycolic acid copolymer in the outer protective layer film. All of these components exhibit excellent biodegradability, allowing them to be decomposed into carbon dioxide and water by microorganisms in various environments. Furthermore, they possess excellent flexibility and processing performance, adapting to different packaging needs and providing basic flexibility, structural support, and a green and environmentally friendly effect for the overall packaging film. This high-barrier environmentally friendly packaging film with antibacterial function also provides stronger antibacterial properties and water solubility through the lysozyme-chitosan quaternary ammonium salt composite antibacterial agent in the biofunctional layer film and proanthocyanidins in the outer protective layer film. It exhibits good inhibitory effects against various bacteria and fungi, protecting the outer surface of the packaging film from microbial erosion. Moreover, its natural origin ensures that it will not pollute the environment after use, aligning with the concept of environmentally friendly packaging.

[0093] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A high-barrier, environmentally friendly packaging film with antibacterial properties, characterized in that, From bottom to top, it consists of a base layer, a nanocomposite barrier layer, a bio-based functional layer, and an outer protective layer, with each layer tightly bonded together by a coated starch-based adhesive. The base layer comprises the following raw materials in the following weight proportions: 850-900 parts of polyhydroxy fatty acid ester, 100-150 parts of composite reinforcing material, and 3-7 parts of natural antioxidant, wherein the natural antioxidant is ferulic acid, and the composite reinforcing material is a composite reinforcing material made of nano-cellulose whiskers and graphene. The nanocomposite barrier layer comprises the following raw materials in the following weight ratios: 750-850 parts polycaprolactone, 120-150 parts antibacterial barrier particles, 5-10 parts environmentally friendly dispersant, and 30-70 parts bio-based plasticizer. The bio-based plasticizer is triethyl citrate, the environmentally friendly dispersant is soybean lecithin, and the antibacterial barrier particles are antibacterial barrier particles made of nano zinc oxide and silicon dioxide composite, with a particle size of 30-60 nm. The bio-based functional layer comprises the following raw materials in the following weight ratios: 450-500 parts konjac glucomannan, 20-50 parts composite antibacterial agent, 20-40 parts natural moisturizer, and 10-30 parts bio-based crosslinking agent. The composite antibacterial agent is a composite antibacterial agent made of lysozyme and chitosan quaternary ammonium salt. The natural moisturizer is sodium hyaluronate, and the bio-based crosslinking agent is tannic acid. The outer protective layer comprises the following raw materials in the following weight ratios: 900-990 parts of polylactic acid-glycolic acid copolymer and 4-10 parts of natural anti-aging agent, wherein the natural anti-aging agent is proanthocyanidins.

2. The high-barrier environmentally friendly packaging film with antibacterial function according to claim 1, characterized in that, The preparation steps of the base layer are as follows: First, prepare the composite reinforcing material: add nanocellulose whiskers and graphene to anhydrous ethanol and ultrasonically disperse for 30-60 minutes to make the nanocellulose whiskers and graphene uniformly dispersed in the ethanol solution to form a stable suspension. The ultrasonic frequency is set to 40-60kHz and the power is 200-400W. The dried polyhydroxy fatty acid ester particles were added to a high-speed mixer, and then the nanocellulose whisker-graphene suspension was slowly poured in. Ferulic acid was added at the same time. The speed of the high-speed mixer was set to 800-1000 r / min and the mixing time was 15-20 minutes to ensure that the components were fully mixed. The mixture is then added to a twin-screw extruder, and the extruder temperature parameters are set as follows: Zone 1 temperature 130-140℃, Zone 2 temperature 140-150℃, Zone 3 temperature 150-160℃, Zone 4 temperature 160-170℃, Die temperature 170-180℃, and screw speed controlled at 180-220 r / min. After the material is melted and blended in the extruder, it is extruded through a T-die and cooled and shaped by cooling rollers to obtain the base film.

3. The high-barrier environmentally friendly packaging film with antibacterial function according to claim 1, characterized in that, The preparation steps of the nanocomposite barrier layer are as follows: First, the antibacterial barrier particles are prepared: nano zinc oxide-silica composite particles are added to deionized water and ultrasonically dispersed for 40-70 minutes at an ultrasonic frequency of 50-70kHz and a power of 250-450W to ensure uniform dispersion of the particles. Then, the water is removed by centrifugation and dried at 60-70℃ for 2-3 hours. The dried polycaprolactone granules, pretreated nano-zinc oxide-silica composite particles, triethyl citrate, and soybean lecithin were sequentially added to a high-speed mixer. After the components were fully mixed, the mixture was fed into a single-screw extruder. The extruder temperatures were set as follows: feeding section temperature 140-150℃, compression section temperature 150-160℃, metering section temperature 160-170℃, and die temperature 170-180℃. The screw speed was controlled at 150-180 r / min. After extrusion, the material was cast into a film using a casting machine. The casting roller temperature was controlled at 25-30℃ to obtain a nano-composite barrier film.

4. The high-barrier environmentally friendly packaging film with antibacterial function according to claim 1, characterized in that, The preparation steps of the bio-based functional layer are as follows: First, prepare a composite antibacterial agent solution: dissolve lysozyme and chitosan quaternary ammonium salt in deionized water to prepare a solution with a mass fraction of 2%-3%, then mix the two solutions at a volume ratio of 1:1 and stir evenly. Then, slowly add konjac glucomannan to deionized water and stir to dissolve at 60-70℃. The mass ratio of konjac glucomannan to water is 1:10-1:

15. The stirring speed is 200-300 r / min and the stirring time is 2-3 hours until a homogeneous solution is formed. Next, konjac glucomannan solution, lysozyme-chitosan quaternary ammonium salt composite antibacterial agent solution, sodium hyaluronate and tannic acid are added to the reaction vessel and stirred at 50-60℃ for 1-2 hours at a stirring speed of 150-250 r / min to form a uniform bio-based functional layer solution. Finally, the bio-based functional layer solution is uniformly coated onto a flat substrate using a blade coating method. The coated substrate is then placed in a drying oven and dried at 40-50°C for 12-24 hours to allow the solvent to fully evaporate and form a bio-based functional layer film.

5. The high-barrier environmentally friendly packaging film with antibacterial function according to claim 1, characterized in that, The preparation steps of the outer protective layer are as follows: polylactic acid-glycolic acid copolymer particles are added to dichloromethane, the mass ratio of polylactic acid-glycolic acid copolymer to dichloromethane is 1:5-1:8, and the mixture is stirred and dissolved at room temperature at a stirring speed of 150-200 r / min for 3-4 hours until a uniform polylactic acid-glycolic acid copolymer solution is formed. Proanthocyanidins were added to a polylactic acid-glycolic acid copolymer solution and stirred until homogeneous at a stirring speed of 100-150 r / min for 30-40 minutes. The mixture was then uniformly coated onto a smooth polyester film and dried naturally at room temperature for 2-3 hours using a casting method to allow some of the dichloromethane to evaporate. The film was then placed in a vacuum drying oven and dried at 40-50℃ and a vacuum of -0.08 to -0.09 MPa for 8-10 hours to obtain an outer protective layer film with a thickness of 10-12 μm.