High-barrier environment-friendly packaging film with antibacterial function

Abstract

The invention relates to the technical field of high-barrier environment-friendly packaging films, and discloses a high-barrier environment-friendly packaging film with an antibacterial function, the high-barrier environment-friendly packaging film comprises a base layer, a nano composite barrier layer, a bio-based functional layer and an outer protective layer from bottom to top in sequence, and the layers are tightly attached through a coated starch-based adhesive. According to the high-barrier environment-friendly packaging film with the antibacterial function, good biodegradability of polyhydroxyalkanoate adopted in the base layer film, polycaprolactone which is adopted in the nano-composite barrier layer film and has a biodegradable function and konjac glucomannan in the biological functional layer film are utilized; the composite packaging film can be decomposed into carbon dioxide and water by microorganisms in various environments, has excellent flexibility and processability, can adapt to different packaging requirements, provides basic flexibility, structural support and green and environment-friendly effects for the whole packaging film, and has a wide application prospect. The procyanidine arranged in the outer protective layer film provides stronger antibacterial property and water solubility for the whole packaging film.

Description

Technical Field

[0001] The present invention relates to the technical field of high-barrier environmentally friendly packaging films, in particular to a high-barrier environmentally friendly packaging film with antibacterial function. Background Art

[0002] Currently, packaging films used for cosmetics, alcoholic beverages, and other products typically consist of PE film laminated with self-adhesive adhesive. However, most PE films currently on the market have poor barrier properties, including poor water and oil resistance, requiring special treatment. Furthermore, commonly used solvent-based adhesives, whether oil-based or water-based, must be diluted with a diluent before use.

[0003] The diluents contain a large amount of ingredients that are harmful to the human body, causing direct pollution to cosmetics, alcoholic beverages, and during the production process, the harmful ingredients in the diluents will evaporate and be discharged into the atmosphere, causing serious pollution to the environment and greatly increasing the production cost of the products. 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

[0004] Technical problems solved In view of the shortcomings of the prior art, the present invention provides a high-barrier composite packaging film with antibacterial function, which has the following advantages and solves the above-mentioned problems.

[0005] (2) Technical solution 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, and the layers are tightly bonded together by applying a starch-based adhesive.

[0006] Preferably, the base layer comprises the following raw materials in the following weight proportions: 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.

[0007] Preferably, the nano-composite barrier layer comprises the following raw materials in the following weight proportions: 750-850 parts of polycaprolactone, 120-150 parts of antibacterial barrier particles, 5-10 parts of environmentally friendly dispersant and 30-70 parts of bio-based plasticizer, the bio-based plasticizer is triethyl citrate, the environmentally friendly dispersant is soy lecithin, the antibacterial barrier particles are antibacterial barrier particles made of a composite of nano-zinc oxide and silicon dioxide, and the particle size of the antibacterial barrier particles is 30-60 nm.

[0008] Preferably, the bio-based functional layer comprises the following raw materials in the following 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 cross-linker, wherein 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 cross-linker is tannic acid.

[0009] 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 a natural anti-aging agent, wherein the natural anti-aging agent is proanthocyanidin.

[0010] Preferably, the preparation steps of the base layer are: First, prepare the composite reinforcement: add nanocellulose whiskers and graphene to anhydrous ethanol and ultrasonically disperse them for 30-60 minutes to uniformly disperse the nanocellulose whiskers and graphene in the ethanol solution to form a stable suspension. The ultrasonic frequency is set to 40-60kHz and the power is 200-400W. Add the dried polyhydroxyalkanoate particles to a high-speed mixer, then slowly pour in the nanocellulose whisker-graphene suspension and add ferulic acid. Set the speed of the high-speed mixer to 800-1000 rpm and mix for 15-20 minutes to ensure that all components are fully mixed. The mixed material is then added to a twin-screw extruder, and the temperature parameters of the extruder are set: zone 1 temperature 130-140°C, zone 2 temperature 140-150°C, zone 3 temperature 150-160°C, zone 4 temperature 160-170°C, die head temperature 170-180°C, and the screw speed is controlled at 180-220r / min. After the materials are melt-blended in the extruder, they are extruded through a T-die, cooled and shaped by a cooling roller to obtain a base film.

[0011] Preferably, the steps for preparing the nanocomposite barrier layer are: 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 50-70 kHz and a power of 250-450 W to uniformly disperse the particles. The water is then removed by centrifugation and the particles are dried at 60-70°C for 2-3 hours. The dried polycaprolactone particles, pretreated nano zinc oxide-silicon dioxide composite particles, triethyl citrate and soybean lecithin are added to a high-speed mixer in sequence, and after the components are fully mixed, the mixture is added to a single-screw extruder, and the extruder temperature is set as follows: the feeding section temperature is 140-150°C, the compression section temperature is 150-160°C, the metering section temperature is 160-170°C, and the die head temperature is 170-180°C; the screw speed is controlled at 150-180 r / min, and after the material is extruded, it is cast into a film through a casting machine, and the casting roller temperature is controlled at 25-30°C to obtain a nano-composite barrier layer film.

[0012] Preferably, the steps for preparing the bio-based functional layer are: First, a composite antimicrobial solution was prepared: lysozyme and chitosan quaternary ammonium salt were dissolved in deionized water to prepare a solution with a mass fraction of 2%-3%, and then the two solutions were mixed in a volume ratio of 1:1 and stirred evenly; Then, konjac glucomannan is slowly added to deionized water and stirred to dissolve at 60-70° C., with a mass ratio of konjac glucomannan to water of 1:10-1:15, a stirring speed of 200-300 r / min, and a stirring time of 2-3 hours, until a uniform solution is formed; Then, the konjac glucomannan solution, the lysozyme-chitosan quaternary ammonium salt composite antibacterial agent solution, sodium hyaluronate and tannic acid were added to the reactor, and stirred at 50-60° C. 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 evenly coated on a flat substrate using a doctor blade method. The coated substrate is 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.

[0013] Preferably, the outer protective layer is prepared by adding polylactic acid-glycolic acid copolymer particles to dichloromethane, wherein the mass ratio of polylactic acid-glycolic acid copolymer to dichloromethane is 1:5-1:8, stirring and dissolving 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 are added to a polylactic acid-glycolic acid copolymer solution and stirred evenly at a stirring speed of 100-150 r / min for 30-40 minutes. The mixed solution is evenly coated on a smooth polyester film and naturally dried at room temperature for 2-3 hours by a casting method to partially volatilize the dichloromethane. The film is then placed in a vacuum drying oven and dried for 8-10 hours at 40-50°C and a vacuum degree of -0.08-0.09 MPa to obtain an outer protective layer film with a thickness of 10-12 μm.

[0014] (3) Beneficial effects 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: 1. This high-barrier, environmentally friendly packaging film with antibacterial function utilizes the good biodegradability of polyhydroxyalkanoate used in the base film, biodegradable polycaprolactone used in the nanocomposite barrier layer, konjac glucomannan in the biofunctional layer film, and polylactic acid-glycolic acid copolymer in the outer protective layer. These films can be decomposed into carbon dioxide and water by microorganisms in a variety of environments. They also have excellent flexibility and processing properties, can adapt to different packaging needs, and provide basic flexibility and structural support for the overall packaging film, as well as green and environmentally friendly effects.

[0015] 2. This high-barrier environmentally friendly packaging film with antibacterial function provides the overall packaging film with stronger antibacterial properties and water solubility through the lysozyme-chitosan quaternary ammonium salt composite antibacterial agent set in the biological functional layer film and the proanthocyanidins in the outer protective layer film. It can have a good inhibitory effect on a variety of bacteria and fungi, and can protect the outer surface of the packaging film from microbial erosion. In addition, its natural origin means that it will not pollute the environment after use, which is in line with the concept of environmentally friendly packaging. DETAILED DESCRIPTION

[0016] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0017] Example 1: A high-barrier, environmentally friendly packaging film with antibacterial function, comprising, 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 by a coated starch-based adhesive; The base layer comprises the following raw materials in the following weight proportions: 850 parts of polyhydroxyalkanoate, 100 parts of composite reinforcement and 3 parts of natural antioxidant, wherein the natural antioxidant is ferulic acid, and the composite reinforcement is a composite reinforcement made of nanocellulose whiskers and graphene; The preparation steps of the base layer are: First, the composite reinforcement was prepared by adding nanocellulose whiskers and graphene to anhydrous ethanol and ultrasonically dispersing them for 30 minutes to uniformly disperse the nanocellulose whiskers and graphene in the ethanol solution to form a stable suspension. The ultrasonic frequency was set to 40 kHz and the power was 200 W. Add the dried polyhydroxyalkanoate particles to a high-speed mixer, then slowly pour in the nanocellulose whisker-graphene suspension and add ferulic acid. Set the speed of the high-speed mixer to 800 rpm and mix for 15 minutes to ensure that all components are fully mixed. The mixed material was then added to a twin-screw extruder, and the temperature parameters of the extruder were set as follows: zone 1 temperature 130°C, zone 2 temperature 140°C, zone 3 temperature 150°C, zone 4 temperature 160°C, die head temperature 170°C, and the screw speed was controlled at 180 r / min. After the materials were melt-blended in the extruder, they were extruded through a T-die and cooled and shaped by a cooling roller to obtain a base film. The nanocomposite barrier layer includes the following raw materials in the following weight proportions: 750 parts of polycaprolactone, 120 parts of antibacterial barrier particles, 5 parts of environmentally friendly dispersant and 30 parts of bio-based plasticizer, wherein the bio-based plasticizer is triethyl citrate, the environmentally friendly dispersant is soy lecithin, and the antibacterial barrier particles are antibacterial barrier particles made of a composite of nano zinc oxide and silicon dioxide, and the particle size of the antibacterial barrier particles is 30 nm; The preparation steps of the nanocomposite barrier layer are as follows: First, the antibacterial barrier particles were prepared: the composite particles were added to deionized water and ultrasonically dispersed for 40 minutes at an ultrasonic frequency of 50 kHz and a power of 250 W to uniformly disperse the particles. The water was then removed by centrifugation, and the particles were dried at 60°C for 2 hours. Dried polycaprolactone particles, pretreated nano zinc oxide-silicon dioxide composite particles, triethyl citrate, and soybean lecithin were sequentially added to a high-speed mixer, and after the components were thoroughly mixed, the mixture was added to a single-screw extruder. The extruder temperature was set at 140°C in the feeding section, 150°C in the compression section, 160°C in the metering section, and 170°C in the die head. The screw speed was controlled at 150 r / min, and after extrusion, the material was cast into a film using a casting machine. The casting roll temperature was controlled at 25°C to obtain a nanocomposite barrier layer film. The bio-based functional layer includes the following raw materials in the following weight proportions: 450 parts of konjac glucomannan, 20 parts of a composite antibacterial agent, 20 parts of a natural moisturizer, and 10 parts of a bio-based cross-linking agent, wherein 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 cross-linking agent is tannic acid; The preparation steps of the bio-based functional layer are as follows: First, a composite antimicrobial solution was prepared: lysozyme and chitosan quaternary ammonium salt were dissolved in deionized water to prepare a 2% solution by mass, and then the two solutions were mixed in a volume ratio of 1:1 and stirred evenly. Then, konjac glucomannan was slowly added to deionized water and stirred to dissolve at 60° C., with a mass ratio of konjac glucomannan to water of 1:10, a stirring speed of 200 r / min, and a stirring time of 2 hours, until a uniform solution was formed; Then, the konjac glucomannan solution, lysozyme-chitosan quaternary ammonium salt composite antibacterial agent solution, sodium hyaluronate, and tannic acid were added to the reactor 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; Finally, the bio-based functional layer solution is evenly coated on a flat substrate using a doctor blade coating method. The coated substrate is 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. The outer protective layer comprises the following raw materials in the following weight proportions: 900 parts of polylactic acid-glycolic acid copolymer and 4 parts of a natural anti-aging agent, wherein the natural anti-aging agent is proanthocyanidin; The outer protective layer was prepared by adding polylactic acid-co-glycolic acid copolymer particles into dichloromethane at a mass ratio of 1:5, stirring and dissolving at room temperature at a stirring speed of 150 r / min for 3 hours until a uniform polylactic acid-co-glycolic acid copolymer solution was formed; Add proanthocyanidins to the polylactic acid-glycolic acid copolymer solution and stir evenly at a stirring speed of 100 r / min for 30 minutes. The mixed solution is evenly coated on a smooth polyester film and naturally dried at room temperature for 2 hours using a casting method to partially evaporate the dichloromethane. Then, place it in a vacuum drying oven and dry it at 40°C and a vacuum degree of -0.08 MPa for 8 hours to obtain an outer protective layer film with a thickness of 10 μm.

[0018] Example 2: A high-barrier, environmentally friendly packaging film with antibacterial function, comprising, 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 by a coated starch-based adhesive; The base layer comprises the following raw materials in the following weight proportions: 900 parts of polyhydroxyalkanoate, 150 parts of composite reinforcement and 7 parts of natural antioxidant, wherein the natural antioxidant is ferulic acid, and the composite reinforcement is a composite reinforcement made of nanocellulose whiskers and graphene; The preparation steps of the base layer are: First, the composite reinforcement was prepared by adding nanocellulose whiskers and graphene to anhydrous ethanol and ultrasonically dispersing them for 60 minutes to uniformly disperse the nanocellulose whiskers and graphene in the ethanol solution to form a stable suspension. The ultrasonic frequency was set to 60 kHz and the power was 400 W. The dried polyhydroxyalkanoate particles were added to a high-speed mixer, and then the nanocellulose whisker-graphene suspension was slowly poured in. Ferulic acid was also added at the same time. The speed of the high-speed mixer was set to 1000 rpm and the mixing time was 20 minutes to ensure that all components were fully mixed. The mixed material was then added to a twin-screw extruder, and the temperature parameters of the extruder were set as follows: zone 1 temperature 140°C, zone 2 temperature 150°C, zone 3 temperature 160°C, zone 4 temperature 170°C, die head temperature 180°C, and screw speed controlled at 220 r / min. After the materials were melt-blended in the extruder, they were extruded through a T-die and cooled and shaped by a cooling roller to obtain a base film. The nanocomposite barrier layer comprises the following raw materials in the following weight proportions: 850 parts of polycaprolactone, 150 parts of antibacterial barrier particles, 10 parts of an environmentally friendly dispersant, and 70 parts of a bio-based plasticizer. The bio-based plasticizer is triethyl citrate, the environmentally friendly dispersant is soy lecithin, and the antibacterial barrier particles are antibacterial barrier particles made of a composite of nano-zinc oxide and silicon dioxide. The particle size of the antibacterial barrier particles is 60 nm. The preparation steps of the nanocomposite barrier layer are as follows: 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 uniformly disperse the particles. Water was then removed by centrifugation, and the particles were dried at 70°C for 3 hours. Dried polycaprolactone particles, pretreated nano zinc oxide-silicon dioxide composite particles, triethyl citrate, and soybean lecithin were sequentially added to a high-speed mixer, and after the components were thoroughly mixed, the mixture was added to a single-screw extruder. The extruder temperature was set to 150°C in the feeding section, 160°C in the compression section, 170°C in the metering section, and 180°C in the die head. The screw speed was controlled at 180 r / min, and after extrusion, the material was cast into a film using a casting machine, with the casting roll temperature controlled at 30°C, to obtain a nanocomposite barrier layer film. The bio-based functional layer includes the following raw materials in the following weight proportions: 500 parts of konjac glucomannan, 50 parts of a composite antibacterial agent, 40 parts of a natural moisturizer, and 30 parts of a bio-based cross-linking agent, wherein 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 cross-linking agent is tannic acid; The preparation steps of the bio-based functional layer are as follows: First, a composite antimicrobial solution was prepared: lysozyme and chitosan quaternary ammonium salt were dissolved in deionized water to prepare a 3% solution by mass, and then the two solutions were mixed in a volume ratio of 1:1 and stirred evenly. Then, konjac glucomannan was slowly added to deionized water and stirred to dissolve at 70° C., with a mass ratio of konjac glucomannan to water of 1:15, a stirring speed of 300 r / min, and a stirring time of 3 hours, until a uniform solution was formed; Then, the konjac glucomannan solution, lysozyme-chitosan quaternary ammonium salt composite antibacterial agent solution, sodium hyaluronate, and tannic acid were added to the reactor 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; Finally, the bio-based functional layer solution is evenly coated on a flat substrate using a doctor blade coating method. The coated substrate is placed in a drying oven and dried at 50°C for 24 hours to fully evaporate the solvent and form a bio-based functional layer film. The outer protective layer comprises the following raw materials in the following weight proportions: 990 parts of polylactic acid-glycolic acid copolymer and 10 parts of a natural anti-aging agent, wherein the natural anti-aging agent is proanthocyanidin; The outer protective layer was prepared by adding polylactic acid-co-glycolic acid copolymer particles into dichloromethane at a mass ratio of 1:8, stirring and dissolving the polylactic acid-co-glycolic acid copolymer at room temperature at a stirring speed of 200 r / min for 4 hours until a uniform polylactic acid-co-glycolic acid copolymer solution was formed; Add proanthocyanidins to the polylactic acid-glycolic acid copolymer solution and stir evenly at a stirring speed of 150 r / min for 40 minutes. The mixed solution is evenly coated on a smooth polyester film and naturally dried at room temperature for 3 hours using a casting method to partially evaporate the dichloromethane. Then, it is placed in a vacuum drying oven and dried at 50°C and a vacuum degree of -0.09 MPa for 10 hours to obtain an outer protective layer film with a thickness of 12 μm.

[0019] Example 3: A high-barrier, environmentally friendly packaging film with antibacterial function, comprising, 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 by a coated starch-based adhesive; The base layer comprises the following raw materials in the following weight proportions: 850 parts of polyhydroxyalkanoate, 100 parts of composite reinforcement and 3 parts of natural antioxidant, wherein the natural antioxidant is ferulic acid, and the composite reinforcement is a composite reinforcement made of nanocellulose whiskers and graphene; The preparation steps of the base layer are: First, the composite reinforcement was prepared by adding nanocellulose whiskers and graphene to anhydrous ethanol and ultrasonically dispersing them for 30 minutes to uniformly disperse the nanocellulose whiskers and graphene in the ethanol solution to form a stable suspension. The ultrasonic frequency was set to 40 kHz and the power was 200 W. Add the dried polyhydroxyalkanoate particles to a high-speed mixer, then slowly pour in the nanocellulose whisker-graphene suspension and add ferulic acid. Set the speed of the high-speed mixer to 800 rpm and mix for 15 minutes to ensure that all components are fully mixed. The mixed material was then added to a twin-screw extruder, and the temperature parameters of the extruder were set as follows: zone 1 temperature 130°C, zone 2 temperature 140°C, zone 3 temperature 150°C, zone 4 temperature 160°C, die head temperature 170°C, and the screw speed was controlled at 180 r / min. After the materials were melt-blended in the extruder, they were extruded through a T-die and cooled and shaped by a cooling roller to obtain a base film. The nanocomposite barrier layer comprises the following raw materials in the following weight proportions: 850 parts of polycaprolactone, 150 parts of antibacterial barrier particles, 10 parts of an environmentally friendly dispersant, and 70 parts of a bio-based plasticizer. The bio-based plasticizer is triethyl citrate, the environmentally friendly dispersant is soy lecithin, and the antibacterial barrier particles are antibacterial barrier particles made of a composite of nano-zinc oxide and silicon dioxide. The particle size of the antibacterial barrier particles is 60 nm. The preparation steps of the nanocomposite barrier layer are as follows: 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 uniformly disperse the particles. Water was then removed by centrifugation, and the particles were dried at 70°C for 3 hours. Dried polycaprolactone particles, pretreated nano zinc oxide-silicon dioxide composite particles, triethyl citrate, and soybean lecithin were sequentially added to a high-speed mixer, and after the components were thoroughly mixed, the mixture was added to a single-screw extruder. The extruder temperature was set to 150°C in the feeding section, 160°C in the compression section, 170°C in the metering section, and 180°C in the die head. The screw speed was controlled at 180 r / min, and after extrusion, the material was cast into a film using a casting machine, with the casting roll temperature controlled at 30°C, to obtain a nanocomposite barrier layer film. The bio-based functional layer includes the following raw materials in the following weight proportions: 500 parts of konjac glucomannan, 50 parts of a composite antibacterial agent, 40 parts of a natural moisturizer, and 30 parts of a bio-based cross-linking agent, wherein 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 cross-linking agent is tannic acid; The preparation steps of the bio-based functional layer are as follows: First, a composite antimicrobial solution was prepared: lysozyme and chitosan quaternary ammonium salt were dissolved in deionized water to prepare a 3% solution by mass, and then the two solutions were mixed in a volume ratio of 1:1 and stirred evenly. Then, konjac glucomannan was slowly added to deionized water and stirred to dissolve at 70° C., with a mass ratio of konjac glucomannan to water of 1:15, a stirring speed of 300 r / min, and a stirring time of 3 hours, until a uniform solution was formed; Then, the konjac glucomannan solution, lysozyme-chitosan quaternary ammonium salt composite antibacterial agent solution, sodium hyaluronate, and tannic acid were added to the reactor 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; Finally, the bio-based functional layer solution is evenly coated on a flat substrate using a doctor blade coating method. The coated substrate is placed in a drying oven and dried at 50°C for 24 hours to fully evaporate the solvent and form a bio-based functional layer film. The outer protective layer comprises the following raw materials in the following weight proportions: 900 parts of polylactic acid-glycolic acid copolymer and 4 parts of a natural anti-aging agent, wherein the natural anti-aging agent is proanthocyanidin; The outer protective layer was prepared by adding polylactic acid-co-glycolic acid copolymer particles into dichloromethane at a mass ratio of 1:5, stirring and dissolving at room temperature at a stirring speed of 150 r / min for 3 hours until a uniform polylactic acid-co-glycolic acid copolymer solution was formed; Add proanthocyanidins to the polylactic acid-glycolic acid copolymer solution and stir evenly at a stirring speed of 100 r / min for 30 minutes. The mixed solution is evenly coated on a smooth polyester film and naturally dried at room temperature for 2 hours using a casting method to partially evaporate the dichloromethane. Then, place it in a vacuum drying oven and dry it at 40°C and a vacuum degree of -0.08 MPa for 8 hours to obtain an outer protective layer film with a thickness of 10 μm.

[0020] The beneficial effects of the present invention are as follows: the high-barrier environmentally friendly packaging film with antibacterial function utilizes the good biodegradability of the polyhydroxyalkanoate used in the base film, the biodegradable polycaprolactone used in the nanocomposite barrier layer film, the konjac glucomannan in the biofunctional layer film, and the polylactic acid-glycolic acid copolymer in the outer protective layer film, all of which can be decomposed into carbon dioxide and water by microorganisms in various environments, and has excellent flexibility and processing properties, can adapt to different packaging requirements, and provide basic flexibility and structural support and green environmental protection effects for the overall packaging film; the high-barrier environmentally friendly packaging film with antibacterial function provides the overall packaging film with stronger antibacterial properties and water solubility through the lysozyme-chitosan quaternary ammonium salt composite antibacterial agent provided in the biofunctional layer film and the proanthocyanidins in the outer protective layer film, can effectively inhibit various bacteria and fungi, can protect the outer surface of the packaging film from microbial erosion, and its natural origin means that it will not pollute the environment after use, which is in line with the concept of environmentally friendly packaging.

[0021] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A high barrier environmentally friendly packaging film with antibacterial function, characterized in that: It includes, from bottom to top, a base layer, a nano-composite barrier layer, a bio-based functional layer and an outer protective layer, and each layer is tightly bonded together by applying a starch-based adhesive.

2. The high barrier environmentally friendly packaging film with antibacterial function according to claim 1, characterized in that: The base layer comprises the following raw materials in proportion by weight: 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 nano-cellulose whiskers and graphene.

3. The high barrier environmentally friendly packaging film with antibacterial function according to claim 1, characterized in that: The nano-composite barrier layer includes the following raw materials in the following weight proportions: 750-850 parts of polycaprolactone, 120-150 parts of antibacterial barrier particles, 5-10 parts of environmentally friendly dispersant and 30-70 parts of bio-based plasticizer, wherein 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 a composite of nano-zinc oxide and silicon dioxide, and the particle size of the antibacterial barrier particles is 30-60 nm.

4. The high barrier environmentally friendly packaging film with antibacterial function according to claim 1, characterized in that: The bio-based functional layer includes the following raw materials in the following weight proportions: 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 cross-linking agent. The composite antibacterial agent is a composite antibacterial agent prepared by combining lysozyme and chitosan quaternary ammonium salt, the natural moisturizer is sodium hyaluronate, and the bio-based cross-linking agent is tannic acid.

5. The high barrier environmentally friendly packaging film with antibacterial function according to claim 1, characterized in that: The outer protective layer comprises the following raw materials in the following weight proportions: 900-990 parts of polylactic acid-glycolic acid copolymer and 4-10 parts of a natural anti-aging agent, wherein the natural anti-aging agent is proanthocyanidin.

6. 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: First, prepare the composite reinforcement: add nanocellulose whiskers and graphene to anhydrous ethanol and ultrasonically disperse them for 30-60 minutes to uniformly disperse the nanocellulose whiskers and graphene in the ethanol solution to form a stable suspension. The ultrasonic frequency is set to 40-60kHz and the power is 200-400W. Add the dried polyhydroxyalkanoate particles to a high-speed mixer, then slowly pour in the nanocellulose whisker-graphene suspension and add ferulic acid. Set the speed of the high-speed mixer to 800-1000 rpm and mix for 15-20 minutes to ensure that all components are fully mixed. The mixed material is then added to a twin-screw extruder, and the temperature parameters of the extruder are set: zone 1 temperature 130-140°C, zone 2 temperature 140-150°C, zone 3 temperature 150-160°C, zone 4 temperature 160-170°C, die head temperature 170-180°C, and the screw speed is controlled at 180-220r / min. After the materials are melt-blended in the extruder, they are extruded through a T-die, cooled and shaped by a cooling roller to obtain a base film.

7. 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: the composite particles are added to deionized water and ultrasonically dispersed for 40-70 minutes at an ultrasonic frequency of 50-70 kHz and a power of 250-450 W to uniformly disperse the particles. The water is then removed by centrifugation and the particles are dried at 60-70°C for 2-3 hours. The dried polycaprolactone particles, pretreated nano zinc oxide-silicon dioxide composite particles, triethyl citrate and soybean lecithin are added to a high-speed mixer in sequence, and after the components are fully mixed, the mixture is added to a single-screw extruder, and the extruder temperature is set as follows: the feeding section temperature is 140-150°C, the compression section temperature is 150-160°C, the metering section temperature is 160-170°C, and the die head temperature is 170-180°C; the screw speed is controlled at 150-180 r / min, and after the material is extruded, it is cast into a film through a casting machine, and the casting roller temperature is controlled at 25-30°C to obtain a nano-composite barrier layer film.

8. 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: First, a composite antimicrobial solution was prepared: lysozyme and chitosan quaternary ammonium salt were dissolved in deionized water to prepare a solution with a mass fraction of 2%-3%, and then the two solutions were mixed in a volume ratio of 1:1 and stirred evenly; Then, konjac glucomannan is slowly added to deionized water and stirred to dissolve at 60-70° C., with a mass ratio of konjac glucomannan to water of 1:10-1:15, a stirring speed of 200-300 r / min, and a stirring time of 2-3 hours, until a uniform solution is formed; Then, the konjac glucomannan solution, the lysozyme-chitosan quaternary ammonium salt composite antibacterial agent solution, sodium hyaluronate and tannic acid were added to the reactor, and stirred at 50-60° C. 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 evenly coated on a flat substrate using a doctor blade method. The coated substrate is 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.

9. The high barrier environmentally friendly packaging film with antibacterial function according to claim 1, characterized in that: The outer protective layer is prepared by 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 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 are added to a polylactic acid-glycolic acid copolymer solution and stirred evenly at a stirring speed of 100-150 r / min for 30-40 minutes. The mixed solution is evenly coated on a smooth polyester film and naturally dried at room temperature for 2-3 hours by a casting method to partially volatilize the dichloromethane. The film is then placed in a vacuum drying oven and dried for 8-10 hours at 40-50°C and a vacuum degree of -0.08-0.09 MPa to obtain an outer protective layer film with a thickness of 10-12 μm.