Degradable antibacterial matt heat-seal film and preparation method thereof

Abstract

The present application relates to a kind of degradable antibacterial matt type heat-seal film and its preparation method, belong to biodegradable packaging film technical field, degradable antibacterial matt type heat-seal film is made of matt surface layer and antibacterial contact layer;The total thickness of the heat-seal film is 25-80 μm, wherein the thickness of matt surface layer is 22-75 μm, antibacterial contact layer dry film thickness is 1-5 μm;The matt surface layer is made by matt surface layer master batch by flow casting process, and the matt surface layer master batch is made from the following weight parts raw materials:40-55 parts PBAT, 20-35 parts PLA, 1.5-3 parts compatible agent, 3-8 parts matt powder, 0.3-0.8 parts oleic acid amide, 0.2-0.5 parts antioxidant 1010.PBAT / PLA degradation resin is used as matrix, and matt surface layer master batch is used to build matt surface layer, and water-based antibacterial spray coating is cured to form double-layer composite structure, compared with traditional degradable heat-seal film, the present application effectively solves the defects of traditional degradation film, such as poor heat-seal performance, uneven matt, no antibacterial function and low degradation efficiency, by optimizing formula system and double-layer composite process.

Description

Technical Field

[0001] This invention belongs to the field of biodegradable packaging film technology, specifically relating to a biodegradable antibacterial matte heat-sealing film and its preparation method. Background Technology

[0002] Biodegradable packaging films are gradually replacing traditional petroleum-based plastic films and are widely used in packaging for food, daily necessities, and fresh produce preservation. Among them, PBAT and PLA, as mainstream fully biodegradable resins, have excellent compostability and processability, making them the core substrates for preparing environmentally friendly heat-sealing packaging films. They can effectively solve the problems of difficult degradation and serious environmental pollution caused by traditional plastic packaging waste.

[0003] However, most conventional biodegradable heat-sealable films currently available have a high-gloss finish and a limited appearance, making them unsuitable for matte packaging needs. The industry typically achieves a matte effect by directly adding matte powder, but ordinary matte fillers have poor compatibility with the resin matrix and are prone to agglomeration. This not only results in uneven matting and numerous appearance defects in the film but also damages the internal structure of the film, significantly reducing its heat-sealing strength. Consequently, the packaging seal is prone to peeling, cracking, and leakage, leading to poor stability in use. On the other hand, existing biodegradable heat-sealable films generally lack antibacterial properties, making them prone to microbial growth when used for food and fresh produce packaging, resulting in limited preservation effects. Summary of the Invention

[0004] The purpose of this invention is to provide a biodegradable antibacterial matte heat-sealing film and its preparation method in order to solve the above-mentioned problems.

[0005] The present invention achieves the above objectives through the following technical solutions:

[0006] This invention provides a biodegradable antibacterial matte heat-sealing film, which is composed of a matte surface layer and an antibacterial contact layer; the total thickness of the heat-sealing film is 25-80μm, wherein the thickness of the matte surface layer is 22-75μm and the dry film thickness of the antibacterial contact layer is 1-5μm;

[0007] The matte surface layer is obtained by casting a matte surface layer masterbatch, which is made from the following raw materials in parts by weight: 40-55 parts PBAT, 20-35 parts PLA, 1.5-3 parts compatibilizer, 3-8 parts matting powder, 0.3-0.8 parts oleamide, and 0.2-0.5 parts antioxidant 1010;

[0008] The antibacterial contact layer is obtained by spraying a water-based antibacterial spray coating onto a matte surface treated with corona and then drying and curing it; the water-based antibacterial spray coating is made from the following raw materials in parts by weight: 40-70 parts water-based polyurethane emulsion, 5-15 parts antibacterial particles, 0.5-2 parts dispersant and 20-30 parts deionized water.

[0009] As a further optimization of the present invention, the matting powder is made by mixing modified silica powder with a pore volume of 0.6-0.9 mL / g and cross-linked styrene-acrylate microspheres, and then subjecting the mixture to ultrasonic vibration for 20-40 min to couple the pores, forming a porous composite carrier, which is then used as the matting powder.

[0010] As a further optimization of the present invention, the particle size of the silica powder with a pore volume of 0.6-0.9 mL / g is 2-4.5 μm; the particle size of the cross-linked styrene-acrylate microspheres is 0.5-0.8 μm.

[0011] As a further optimization of the present invention, the modified silica powder is obtained by modifying silica powder with silane. The specific modification process is as follows:

[0012] (a) Mix ethanol and deionized water, add glacial acetic acid to adjust the pH of the mixture to 4.5-5.5, add 2.5-5wt% KH-570 based on the mass of silica powder, stir at room temperature for 15-25 min, and the silane will be fully hydrolyzed to generate silanol to obtain the hydrolysate.

[0013] (ii) Add silica powder to the hydrolysate, stir at high speed 300-600 rpm, prepare a slurry with a solid content of 25-35%, gradually raise the temperature to 70-80℃, and keep it at the temperature while stirring for 1.5-2.5 hours;

[0014] (iii) The slurry after reaction is filtered by plate and frame filter press, washed 2-3 times with anhydrous ethanol to remove unreacted free silane, the filter cake is dried at 105-120℃, and then air-jet pulverized through a 325-400 mesh sieve to obtain modified silica powder.

[0015] As a further optimization of the present invention, the mass ratio of ethanol to deionized water is 0.2:1.

[0016] As a further optimization of the present invention, the preparation process of the antibacterial particles is as follows:

[0017] (a) Select fresh, mold-free mugwort leaves, mint leaves, papaya leaves and sesame leaves, wash to remove surface impurities, cut into 2-5mm fragments, and use a freeze-thaw cycle process to perform osmotic pressure membrane breaking treatment. Repeat the freeze-thaw cycle 2-3 times to obtain pretreated plant leaf material; the single freezing condition is -20℃ and heat preservation for 30min, and the single thawing is natural thawing at room temperature;

[0018] (ii) Add the pretreated plant leaf material to a sodium dodecyl sulfate aqueous solution and perform constant temperature stirring extraction for 12-24 hours; wherein the mass concentration of the sodium dodecyl sulfate aqueous solution is 0.5-1wt%, the material-liquid ratio is 1:20-30, and the treatment temperature is 35-40℃.

[0019] (iii) Take out the processed plant leaf material, repeatedly soak and rinse it with deionized water until there is no foam residue in the rinse water, and then rinse it with Tris-HCl buffer to remove residual sodium dodecyl sulfate and intracellular dissolution impurities to obtain plant leaf pre-processed material.

[0020] (iv) The plant leaf pre-made material is immersed in the concentrated antibacterial extract of Artemisia argyi and a vacuum-assisted impregnation process is adopted. The process parameters of vacuum-assisted impregnation are: vacuum degree -0.06~-0.09MPa, impregnation temperature 25-35℃, impregnation time 2-4h, stirring speed 60-120r / min throughout the process, and solid-liquid separation is carried out after stirring. The solid material is taken to obtain the wet antibacterial material loaded with active components.

[0021] (v) The wet antibacterial material is vacuum-frozen for 8-12 hours at a vacuum degree of 10-50 Pa and a cold trap temperature of -40 to -55℃. After drying, it is gently pulverized and passed through an 80-200 mesh sieve to obtain antibacterial particles.

[0022] As a further optimization of the present invention, the preparation method of the antibacterial extract concentrate of Artemisia argyi is as follows: dried Artemisia argyi is mixed and extracted with an ethanol aqueous solution, the volume fraction of the ethanol aqueous solution is 60-80%, the material-liquid ratio of dried Artemisia argyi to ethanol aqueous solution is 1:15-1:25, the extraction is carried out under constant temperature reflux for 1-2 hours, the extract is collected by filtration, and concentrated under reduced pressure until the solid content is 15-25% to obtain the antibacterial extract concentrate of Artemisia argyi.

[0023] As a further optimization of the present invention, the mass ratio of mugwort leaves, peppermint leaves, papaya leaves and sesame leaves is 1:0.2:0.6:0.8.

[0024] This invention also provides a method for preparing a biodegradable antibacterial matte heat-sealable film, comprising the following steps:

[0025] Preparation of matte surface layer:

[0026] (a) Put the dried PBAT and PLA into a high-speed mixer, add compatibilizer, matting powder, oleic acid amide and antioxidant 1010 in sequence, mix in a closed container, control the mixing speed to 800-1200 r / min, the mixing temperature to 40-50℃, and stir at high speed for 8-12 min to make the powder additives and resin matrix evenly dispersed to obtain a homogeneous matting surface premix.

[0027] (ii) The matte surface premix is ​​fed into a twin-screw extruder for melt plasticization, extrusion granulation to obtain matte surface masterbatch, and then the obtained masterbatch is fed into a cast film extruder with a casting die temperature of 160-185℃ to prepare a matte surface; the side of the matte surface to be coated is subjected to corona treatment, and the surface tension after corona treatment is ≥42mN / m;

[0028] Preparation of antibacterial contact layer:

[0029] (a) Mix waterborne polyurethane emulsion, antibacterial particles, dispersant and deionized water until homogeneous to obtain antibacterial spray coating;

[0030] (ii) The antibacterial coating is evenly sprayed onto the matte surface that has been corona treated, then dried with hot air at 60-80℃ for 1-3 minutes to evaporate and remove moisture. After curing, an antibacterial contact layer is obtained.

[0031] The beneficial effects of this invention are as follows: This invention uses PBAT / PLA degradable resin as the matrix, combines it with matte surface masterbatch to construct a matte surface layer, and combines it with water-based antibacterial spray coating to form a double-layer composite structure. Compared with traditional degradable heat-sealing films, this invention solves the defects of traditional degradable films such as poor heat-sealing performance, uneven matting, insufficient antibacterial ability, and low degradation efficiency by optimizing the formula system and double-layer composite process.

[0032] Tests showed that the heat-sealing strength of the samples prepared by this invention can reach 1.9-2.3 N / 15mm, and the sealing resistance to peeling and leakage is improved. At the same time, the 28-day composting biodegradation rate can reach 62-65%. In addition, this invention uses green plant-derived antibacterial components, without the addition of harmful heavy metals, and has both excellent matte appearance and long-lasting antibacterial properties. Moreover, the overall preparation process is simple, green and environmentally friendly, and suitable for industrial production, and can be applied to the field of environmentally friendly packaging for food, daily necessities and other products. Detailed Implementation

[0033] The present application will now be described in further detail. It should be noted that the following specific embodiments are only used to further illustrate the present application and should not be construed as limiting the scope of protection of the present application. Those skilled in the art can make some non-essential improvements and adjustments to the present application based on the above application content.

[0034] Unless otherwise specified, all methods used in this invention are conventional methods known to those skilled in the art, and all reagents and materials used are commercially available products.

[0035] In this invention, the compatibilizer is polylactic acid grafted with maleic anhydride; the dispersant is sodium lignosulfonate; and the solid content of the waterborne polyurethane emulsion is 45%.

[0036] Example 1

[0037] The matting agent is made by mixing modified silica powder (particle size 2 μm) with a pore volume of 0.6 mL / g and cross-linked styrene-acrylate microspheres (particle size 0.5 μm), followed by ultrasonic vibration for 20 min to couple the pores and form a porous composite carrier, which is then used as the matting agent. The mass ratio of modified silica powder to cross-linked styrene-acrylate microspheres is 0.2:0.1.

[0038] Modified silica powder is obtained by modifying silica powder with silane. The specific modification process is as follows:

[0039] (a) Mix ethanol and deionized water (mass ratio of ethanol to deionized water is 0.2:1), add glacial acetic acid to adjust the pH of the mixture to 4.5, add 2.5 wt% KH-570 based on the mass of silica powder, stir at room temperature for 15 min, and the silane is fully hydrolyzed to generate silanol to obtain the hydrolysate.

[0040] (ii) Add silica powder to the hydrolysate, stir at high speed for 300 rpm, prepare a slurry with a solid content of 25%, gradually raise the temperature to 70°C, and keep it at the temperature while stirring for 1.5 h.

[0041] (iii) The slurry after reaction was filtered by plate and frame filter press, washed twice with anhydrous ethanol to remove unreacted free silane, the filter cake was dried at 105°C, and then pulverized by air jet through a 325-mesh sieve to obtain modified silica powder.

[0042] The preparation process of antibacterial granules is as follows:

[0043] (a) Select fresh, mold-free mugwort leaves, mint leaves, papaya leaves, and sesame leaves (the mass ratio of mugwort leaves, mint leaves, papaya leaves, and sesame leaves is 1:0.2:0.6:0.8), wash to remove surface impurities, cut into 2mm fragments, and use a freeze-thaw cycle process to perform osmotic pressure membrane breaking treatment. Repeat the freeze-thaw cycle twice to obtain pretreated plant leaf material; the single freezing condition is -20℃ and heat preservation for 30min, and the single thawing is natural thawing at room temperature;

[0044] (ii) The pretreated plant leaf material was added to a sodium dodecyl sulfate aqueous solution and stirred and extracted at a constant temperature for 12 hours; wherein the sodium dodecyl sulfate aqueous solution had a mass concentration of 0.5 wt%, a material-to-liquid ratio of 1:20, and a treatment temperature of 35℃.

[0045] (iii) Take out the processed plant leaf material, repeatedly soak and rinse it with deionized water until there is no foam residue in the rinse water, and then rinse it with Tris-HCl buffer to remove residual sodium dodecyl sulfate and intracellular dissolution impurities to obtain plant leaf pre-processed material.

[0046] (iv) The plant leaf pre-made material is immersed in the concentrated antibacterial extract of Artemisia argyi and a vacuum-assisted impregnation process is adopted. The process parameters of vacuum-assisted impregnation are: vacuum degree -0.06MPa, impregnation temperature 25℃, impregnation time 2h, stirring speed 60r / min throughout the process, and solid-liquid separation is carried out after stirring. The solid material is taken to obtain the wet antibacterial material loaded with active components.

[0047] (v) The wet antibacterial material was vacuum freeze-dried for 8 hours at a vacuum degree of 10 Pa and a cold trap temperature of -40 °C. After drying, it was gently pulverized and passed through an 80-mesh sieve to obtain antibacterial particles.

[0048] The preparation method of the antibacterial extract concentrate of Artemisia argyi is as follows: dried Artemisia argyi leaves are mixed with an ethanol aqueous solution with a volume fraction of 60% and a material-to-liquid ratio of 1:15. The mixture is extracted under constant temperature reflux for 1 hour, filtered and collected, and concentrated under reduced pressure until the solid content is 15% to obtain the antibacterial extract concentrate of Artemisia argyi.

[0049] Preparation of matte surface layer:

[0050] (a) Add 40 parts of dried PBAT and 20 parts of PLA into a high-speed mixer, and add 1.5 parts of compatibilizer, 3 parts of matting powder, 0.3 parts of oleic acid amide and 0.2 parts of antioxidant 1010 in sequence. Mix in a closed container, control the mixing speed at 800 r / min, the mixing temperature at 40℃, and stir at high speed for 8 min to make the powder additives and resin matrix evenly dispersed to obtain a homogeneous matting surface premix.

[0051] (ii) The matte surface premix is ​​fed into a twin-screw extruder for melt plasticization, extrusion granulation to obtain matte surface masterbatch, and then the obtained masterbatch is fed into a cast film extruder with a casting die temperature of 160℃ to prepare a matte surface; the side of the matte surface to be sprayed is subjected to corona treatment, and the surface tension after corona treatment is 42mN / m;

[0052] Preparation of antibacterial contact layer:

[0053] (a) Mix 40 parts of waterborne polyurethane emulsion, 5 parts of antibacterial particles, 0.5 parts of dispersant and 20 parts of deionized water until homogeneous to obtain an antibacterial spray coating.

[0054] (ii) The antibacterial coating is evenly sprayed onto the matte surface that has been corona treated, then dried with hot air at 60°C for 1 minute to evaporate and remove moisture. After curing, an antibacterial contact layer is obtained.

[0055] The total thickness of the heat-sealing film is 65μm, of which the thickness of the matte surface layer is 64μm and the thickness of the antibacterial contact layer dry film is 1μm.

[0056] Example 2

[0057] The matting agent is made by mixing modified silica powder (3 μm particle size) with a pore volume of 0.7 mL / g and cross-linked styrene-acrylate microspheres (0.7 μm particle size) and then ultrasonically vibrating for 30 min to couple the pores, forming a porous composite carrier, which is used as the matting agent; the mass ratio of modified silica powder to cross-linked styrene-acrylate microspheres is 0.2:0.1.

[0058] Modified silica powder is obtained by modifying silica powder with silane. The specific modification process is as follows:

[0059] (a) Mix ethanol and deionized water (mass ratio of ethanol to deionized water is 0.2:1), add glacial acetic acid to adjust the pH of the mixture to 5.0, add 3.5wt% KH-570 based on the mass of silica powder, stir at room temperature for 20min, and the silane is fully hydrolyzed to generate silanol to obtain the hydrolysate.

[0060] (ii) Add silica powder to the hydrolysate, stir at high speed for 450 rpm, prepare a slurry with a solid content of 30%, gradually raise the temperature to 75°C, and keep it at the temperature while stirring for 2 hours;

[0061] (iii) The slurry after reaction was filtered by plate and frame filter press, washed twice with anhydrous ethanol to remove unreacted free silane, the filter cake was dried at 115°C, and then pulverized by air jet through a 370-mesh sieve to obtain modified silica powder.

[0062] The preparation process of antibacterial granules is as follows:

[0063] (a) Select fresh, mold-free mugwort leaves, mint leaves, papaya leaves, and sesame leaves (the mass ratio of mugwort leaves, mint leaves, papaya leaves, and sesame leaves is 1:0.2:0.6:0.8), wash to remove surface impurities, cut into 4mm fragments, and use a freeze-thaw cycle process to perform osmotic pressure membrane breaking treatment. Repeat the freeze-thaw cycle 3 times to obtain pretreated plant leaf material; the single freezing condition is -20℃ and heat preservation for 30min, and the single thawing is natural thawing at room temperature;

[0064] (ii) The pretreated plant leaf material was added to a sodium dodecyl sulfate aqueous solution and subjected to constant temperature stirring and extraction for 18 hours; wherein the sodium dodecyl sulfate aqueous solution had a mass concentration of 0.8 wt%, a material-to-liquid ratio of 1:25, and a treatment temperature of 37℃.

[0065] (iii) Take out the processed plant leaf material, repeatedly soak and rinse it with deionized water until there is no foam residue in the rinse water, and then rinse it with Tris-HCl buffer to remove residual sodium dodecyl sulfate and intracellular dissolution impurities to obtain plant leaf pre-processed material.

[0066] (iv) The plant leaf pre-made material is immersed in the antibacterial extract concentrate of Artemisia argyi and a vacuum-assisted impregnation process is adopted. The process parameters of vacuum-assisted impregnation are: vacuum degree -0.08MPa, impregnation temperature 30℃, impregnation time 3h, stirring speed 100r / min throughout the process, and solid-liquid separation is carried out after stirring. The solid material is taken to obtain the wet antibacterial material loaded with active components.

[0067] (v) The wet antibacterial material was vacuum freeze-dried at a vacuum degree of 35 Pa and a cold trap temperature of -45 °C for 10 h. After drying, it was gently pulverized and passed through a 150-mesh sieve to obtain antibacterial particles.

[0068] The preparation method of the antibacterial extract concentrate of Artemisia argyi is as follows: dried Artemisia argyi leaves are mixed with an ethanol aqueous solution with a volume fraction of 70% and a material-to-liquid ratio of 1:20. The mixture is extracted under constant temperature reflux for 1.5 hours, filtered and collected, and concentrated under reduced pressure until the solid content is 20% to obtain the antibacterial extract concentrate of Artemisia argyi.

[0069] Preparation of matte surface layer:

[0070] (a) Add 50 parts of dried PBAT and 30 parts of PLA into a high-speed mixer, and add 2.5 parts of compatibilizer, 5 parts of matting powder, 0.6 parts of oleic acid amide and 0.4 parts of antioxidant 1010 in sequence. Mix in a closed container, control the mixing speed at 1000 r / min, the mixing temperature at 45℃, and stir at high speed for 10 min to make the powder additives and resin matrix evenly dispersed to obtain a homogeneous matting surface premix.

[0071] (ii) The matte surface premix is ​​fed into a twin-screw extruder for melt plasticization, extrusion granulation to obtain matte surface masterbatch, and then the obtained masterbatch is fed into a cast film extruder with a casting die temperature of 175℃ to prepare a matte surface; the side of the matte surface to be sprayed is subjected to corona treatment, and the surface tension after corona treatment is 42mN / m;

[0072] Preparation of antibacterial contact layer:

[0073] (a) Mix 60 parts of waterborne polyurethane emulsion, 10 parts of antibacterial particles, 1.5 parts of dispersant and 25 parts of deionized water until homogeneous to obtain an antibacterial spray coating.

[0074] (ii) The antibacterial coating is evenly sprayed onto the matte surface that has been corona treated, then dried with hot air at 70°C for 2 minutes to evaporate and remove moisture. After curing, an antibacterial contact layer is obtained.

[0075] The total thickness of the heat-sealing film is 65μm, of which the thickness of the matte surface layer is 62μm and the thickness of the antibacterial contact layer dry film is 3μm.

[0076] Example 3

[0077] The matting agent is made by mixing modified silica powder (particle size 4.5 μm) with a pore volume of 0.9 mL / g and cross-linked styrene-acrylate microspheres (particle size 0.8 μm), followed by ultrasonic vibration for 40 min to couple the pores and form a porous composite carrier, which is then used as the matting agent. The mass ratio of modified silica powder to cross-linked styrene-acrylate microspheres is 0.2:0.1.

[0078] Modified silica powder is obtained by modifying silica powder with silane. The specific modification process is as follows:

[0079] (a) Mix ethanol and deionized water (mass ratio of ethanol to deionized water is 0.2:1), add glacial acetic acid to adjust the pH of the mixture to 5.5, add 5 wt% KH-570 based on the mass of silica powder, stir at room temperature for 25 min, and the silane is fully hydrolyzed to generate silanol to obtain the hydrolysate.

[0080] (ii) Add silica powder to the hydrolysate, stir at high speed for 600 rpm, prepare a slurry with a solid content of 35%, gradually raise the temperature to 80°C, and keep it at the temperature while stirring for 2.5 h;

[0081] (iii) The slurry after reaction was filtered by plate and frame filter press, washed three times with anhydrous ethanol to remove unreacted free silane, the filter cake was dried at 120°C, and then pulverized by air jet through a 400-mesh sieve to obtain modified silica powder.

[0082] The preparation process of antibacterial granules is as follows:

[0083] (a) Select fresh, mold-free mugwort leaves, mint leaves, papaya leaves, and sesame leaves (the mass ratio of mugwort leaves, mint leaves, papaya leaves, and sesame leaves is 1:0.2:0.6:0.8), wash to remove surface impurities, cut into 5mm fragments, and use a freeze-thaw cycle process for osmotic pressure membrane breaking treatment. Repeat the freeze-thaw cycle 3 times to obtain pretreated plant leaf material; the single freezing condition is -20℃ and heat preservation for 30min, and the single thawing is natural thawing at room temperature;

[0084] (ii) The pretreated plant leaf material was added to a sodium dodecyl sulfate aqueous solution and subjected to constant temperature stirring and extraction for 24 hours; wherein the sodium dodecyl sulfate aqueous solution had a mass concentration of 1 wt%, the material-to-liquid ratio was 1:30, and the treatment temperature was 40℃.

[0085] (iii) Take out the processed plant leaf material, repeatedly soak and rinse it with deionized water until there is no foam residue in the rinse water, and then rinse it with Tris-HCl buffer to remove residual sodium dodecyl sulfate and intracellular dissolution impurities to obtain plant leaf pre-processed material.

[0086] (iv) The plant leaf pre-made material is immersed in the concentrated antibacterial extract of Artemisia argyi and a vacuum-assisted impregnation process is adopted. The process parameters of vacuum-assisted impregnation are: vacuum degree -0.09MPa, impregnation temperature 35℃, impregnation time 4h, stirring speed 120r / min throughout the process, and solid-liquid separation is carried out after stirring. The solid material is taken to obtain the wet antibacterial material loaded with active components.

[0087] (v) The wet antibacterial material was vacuum freeze-dried for 12 hours at a vacuum degree of 50 Pa and a cold trap temperature of -55 °C. After drying, it was gently pulverized and passed through a 200-mesh sieve to obtain antibacterial particles.

[0088] The preparation method of the antibacterial extract concentrate of Artemisia argyi is as follows: dried Artemisia argyi leaves are mixed with an ethanol aqueous solution with a volume fraction of 80% and a material-to-liquid ratio of 1:25. The mixture is extracted under constant temperature reflux for 2 hours, filtered and collected, and concentrated under reduced pressure until the solid content is 25% to obtain the antibacterial extract concentrate of Artemisia argyi.

[0089] Preparation of matte surface layer:

[0090] (a) Add 55 parts of dried PBAT and 35 parts of PLA into a high-speed mixer, and add 3 parts of compatibilizer, 8 parts of matting powder, 0.8 parts of oleic acid amide and 0.5 parts of antioxidant 1010 in sequence. Mix in a closed container, control the mixing speed at 1200 r / min, the mixing temperature at 50℃, and stir at high speed for 12 min to make the powder additives and resin matrix evenly dispersed to obtain a homogeneous matting surface premix.

[0091] (ii) The matte surface premix is ​​fed into a twin-screw extruder for melt plasticization, extrusion granulation to obtain matte surface masterbatch, and then the obtained masterbatch is fed into a cast film extruder with a casting die temperature of 185℃ to prepare a matte surface; the side of the matte surface to be sprayed is subjected to corona treatment, and the surface tension after corona treatment is 42mN / m;

[0092] Preparation of antibacterial contact layer:

[0093] (a) Mix 70 parts of waterborne polyurethane emulsion, 15 parts of antibacterial particles, 2 parts of dispersant and 30 parts of deionized water until uniform to obtain an antibacterial spray coating.

[0094] (ii) The antibacterial coating is evenly sprayed onto the matte surface that has been corona treated, then dried with hot air at 80°C for 3 minutes to evaporate and remove moisture. After curing, an antibacterial contact layer is obtained.

[0095] The total thickness of the heat-sealing film is 65μm, of which the thickness of the matte surface layer is 60μm and the thickness of the antibacterial contact layer dry film is 5μm.

[0096] Comparative Example 1

[0097] The matting agent is modified silica powder with a pore volume of 0.7 mL / g and a particle size of 3 μm.

[0098] Modified silica powder is obtained by modifying silica powder with silane. The specific modification process is as follows:

[0099] (a) Mix ethanol and deionized water (mass ratio of ethanol to deionized water is 0.2:1), add glacial acetic acid to adjust the pH of the mixture to 5.0, add 3.5wt% KH-570 based on the mass of silica powder, stir at room temperature for 20min, and the silane is fully hydrolyzed to generate silanol to obtain the hydrolysate.

[0100] (ii) Add silica powder to the hydrolysate, stir at high speed for 450 rpm, prepare a slurry with a solid content of 30%, gradually raise the temperature to 75°C, and keep it at the temperature while stirring for 2 hours;

[0101] (iii) The slurry after reaction was filtered by plate and frame filter press, washed twice with anhydrous ethanol to remove unreacted free silane, the filter cake was dried at 115°C, and then pulverized by air jet through a 370-mesh sieve to obtain modified silica powder.

[0102] The preparation process of antibacterial granules is as follows:

[0103] (a) Select fresh, mold-free mugwort leaves, mint leaves, papaya leaves, and sesame leaves (the mass ratio of mugwort leaves, mint leaves, papaya leaves, and sesame leaves is 1:0.2:0.6:0.8), wash to remove surface impurities, cut into 4mm fragments, and use a freeze-thaw cycle process to perform osmotic pressure membrane breaking treatment. Repeat the freeze-thaw cycle 3 times to obtain pretreated plant leaf material; the single freezing condition is -20℃ and heat preservation for 30min, and the single thawing is natural thawing at room temperature;

[0104] (ii) The pretreated plant leaf material was added to a sodium dodecyl sulfate aqueous solution and subjected to constant temperature stirring and extraction for 18 hours; wherein the sodium dodecyl sulfate aqueous solution had a mass concentration of 0.8 wt%, a material-to-liquid ratio of 1:25, and a treatment temperature of 37℃.

[0105] (iii) Take out the processed plant leaf material, repeatedly soak and rinse it with deionized water until there is no foam residue in the rinse water, and then rinse it with Tris-HCl buffer to remove residual sodium dodecyl sulfate and intracellular dissolution impurities to obtain plant leaf pre-processed material.

[0106] (iv) The plant leaf pre-made material is immersed in the antibacterial extract concentrate of Artemisia argyi and a vacuum-assisted impregnation process is adopted. The process parameters of vacuum-assisted impregnation are: vacuum degree -0.08MPa, impregnation temperature 30℃, impregnation time 3h, stirring speed 100r / min throughout the process, and solid-liquid separation is carried out after stirring. The solid material is taken to obtain the wet antibacterial material loaded with active components.

[0107] (v) The wet antibacterial material was vacuum freeze-dried at a vacuum degree of 35 Pa and a cold trap temperature of -45 °C for 10 h. After drying, it was gently pulverized and passed through a 150-mesh sieve to obtain antibacterial particles.

[0108] The preparation method of the antibacterial extract concentrate of Artemisia argyi is as follows: dried Artemisia argyi leaves are mixed with an ethanol aqueous solution with a volume fraction of 70% and a material-to-liquid ratio of 1:20. The mixture is extracted under constant temperature reflux for 1.5 hours, filtered and collected, and concentrated under reduced pressure until the solid content is 20% to obtain the antibacterial extract concentrate of Artemisia argyi.

[0109] Preparation of matte surface layer:

[0110] (a) Add 50 parts of dried PBAT and 30 parts of PLA into a high-speed mixer, and add 2.5 parts of compatibilizer, 5 parts of matting powder, 0.6 parts of oleic acid amide and 0.4 parts of antioxidant 1010 in sequence. Mix in a closed container, control the mixing speed at 1000 r / min, the mixing temperature at 45℃, and stir at high speed for 10 min to make the powder additives and resin matrix evenly dispersed to obtain a homogeneous matting surface premix.

[0111] (ii) The matte surface premix is ​​fed into a twin-screw extruder for melt plasticization, extrusion granulation to obtain matte surface masterbatch, and then the obtained masterbatch is fed into a cast film extruder with a casting die temperature of 175℃ to prepare a matte surface; the side of the matte surface to be sprayed is subjected to corona treatment, and the surface tension after corona treatment is 42mN / m;

[0112] Preparation of antibacterial contact layer:

[0113] (a) Mix 60 parts of waterborne polyurethane emulsion, 10 parts of antibacterial particles, 1.5 parts of dispersant and 25 parts of deionized water until homogeneous to obtain an antibacterial spray coating.

[0114] (ii) The antibacterial coating is evenly sprayed onto the matte surface that has been corona treated, then dried with hot air at 70°C for 2 minutes to evaporate and remove moisture. After curing, an antibacterial contact layer is obtained.

[0115] The total thickness of the heat-sealing film is 65μm, of which the thickness of the matte surface layer is 62μm and the thickness of the antibacterial contact layer dry film is 3μm.

[0116] Comparative Example 2

[0117] The matting agent is cross-linked styrene-acrylate microspheres (particle size 0.7μm).

[0118] The preparation process of antibacterial granules is as follows:

[0119] (a) Select fresh, mold-free mugwort leaves, mint leaves, papaya leaves, and sesame leaves (the mass ratio of mugwort leaves, mint leaves, papaya leaves, and sesame leaves is 1:0.2:0.6:0.8), wash to remove surface impurities, cut into 4mm fragments, and use a freeze-thaw cycle process to perform osmotic pressure membrane breaking treatment. Repeat the freeze-thaw cycle 3 times to obtain pretreated plant leaf material; the single freezing condition is -20℃ and heat preservation for 30min, and the single thawing is natural thawing at room temperature;

[0120] (ii) The pretreated plant leaf material was added to a sodium dodecyl sulfate aqueous solution and subjected to constant temperature stirring and extraction for 18 hours; wherein the sodium dodecyl sulfate aqueous solution had a mass concentration of 0.8 wt%, a material-to-liquid ratio of 1:25, and a treatment temperature of 37℃.

[0121] (iii) Take out the processed plant leaf material, repeatedly soak and rinse it with deionized water until there is no foam residue in the rinse water, and then rinse it with Tris-HCl buffer to remove residual sodium dodecyl sulfate and intracellular dissolution impurities to obtain plant leaf pre-processed material.

[0122] (iv) The plant leaf pre-made material is immersed in the antibacterial extract concentrate of Artemisia argyi and a vacuum-assisted impregnation process is adopted. The process parameters of vacuum-assisted impregnation are: vacuum degree -0.08MPa, impregnation temperature 30℃, impregnation time 3h, stirring speed 100r / min throughout the process, and solid-liquid separation is carried out after stirring. The solid material is taken to obtain the wet antibacterial material loaded with active components.

[0123] (v) The wet antibacterial material was vacuum freeze-dried at a vacuum degree of 35 Pa and a cold trap temperature of -45 °C for 10 h. After drying, it was gently pulverized and passed through a 150-mesh sieve to obtain antibacterial particles.

[0124] The preparation method of the antibacterial extract concentrate of Artemisia argyi is as follows: dried Artemisia argyi leaves are mixed with an ethanol aqueous solution with a volume fraction of 70% and a material-to-liquid ratio of 1:20. The mixture is extracted under constant temperature reflux for 1.5 hours, filtered and collected, and concentrated under reduced pressure until the solid content is 20% to obtain the antibacterial extract concentrate of Artemisia argyi.

[0125] Preparation of matte surface layer:

[0126] (a) Add 50 parts of dried PBAT and 30 parts of PLA into a high-speed mixer, and add 2.5 parts of compatibilizer, 5 parts of matting powder, 0.6 parts of oleic acid amide and 0.4 parts of antioxidant 1010 in sequence. Mix in a closed container, control the mixing speed at 1000 r / min, the mixing temperature at 45℃, and stir at high speed for 10 min to make the powder additives and resin matrix evenly dispersed to obtain a homogeneous matting surface premix.

[0127] (ii) The matte surface premix is ​​fed into a twin-screw extruder for melt plasticization, extrusion granulation to obtain matte surface masterbatch, and then the obtained masterbatch is fed into a cast film extruder with a casting die temperature of 175℃ to prepare a matte surface; the side of the matte surface to be sprayed is subjected to corona treatment, and the surface tension after corona treatment is 42mN / m;

[0128] Preparation of antibacterial contact layer:

[0129] (a) Mix 60 parts of waterborne polyurethane emulsion, 10 parts of antibacterial particles, 1.5 parts of dispersant and 25 parts of deionized water until homogeneous to obtain an antibacterial spray coating.

[0130] (ii) The antibacterial coating is evenly sprayed onto the matte surface that has been corona treated, then dried with hot air at 70°C for 2 minutes to evaporate and remove moisture. After curing, an antibacterial contact layer is obtained.

[0131] The total thickness of the heat-sealing film is 65μm, of which the thickness of the matte surface layer is 62μm and the thickness of the antibacterial contact layer dry film is 3μm.

[0132] Comparative Example 3

[0133] The matting agent is made by mixing modified silica powder (3 μm particle size) with a pore volume of 0.7 mL / g and cross-linked styrene-acrylate microspheres (0.7 μm particle size) and then ultrasonically vibrating for 30 min to couple the pores, forming a porous composite carrier, which is used as the matting agent; the mass ratio of modified silica powder to cross-linked styrene-acrylate microspheres is 0.2:0.1.

[0134] Modified silica powder is obtained by modifying silica powder with silane. The specific modification process is as follows:

[0135] (a) Mix ethanol and deionized water (mass ratio of ethanol to deionized water is 0.2:1), add glacial acetic acid to adjust the pH of the mixture to 5.0, add 3.5wt% KH-570 based on the mass of silica powder, stir at room temperature for 20min, and the silane is fully hydrolyzed to generate silanol to obtain the hydrolysate.

[0136] (ii) Add silica powder to the hydrolysate, stir at high speed for 450 rpm, prepare a slurry with a solid content of 30%, gradually raise the temperature to 75°C, and keep it at the temperature while stirring for 2 hours;

[0137] (iii) The slurry after reaction was filtered by plate and frame filter press, washed twice with anhydrous ethanol to remove unreacted free silane, the filter cake was dried at 115°C, and then pulverized by air jet through a 370-mesh sieve to obtain modified silica powder.

[0138] Preparation of matte surface layer:

[0139] (a) Add 50 parts of dried PBAT and 30 parts of PLA into a high-speed mixer, and add 2.5 parts of compatibilizer, 5 parts of matting powder, 0.6 parts of oleic acid amide and 0.4 parts of antioxidant 1010 in sequence. Mix in a closed container, control the mixing speed at 1000 r / min, the mixing temperature at 45℃, and stir at high speed for 10 min to make the powder additives and resin matrix evenly dispersed to obtain a homogeneous matting surface premix.

[0140] (ii) The matte surface premix is ​​fed into a twin-screw extruder for melt plasticization, extrusion granulation to obtain matte surface masterbatch, and then the obtained masterbatch is fed into a cast film extruder with a casting die temperature of 175℃ to prepare a matte surface; the side of the matte surface to be sprayed is subjected to corona treatment, and the surface tension after corona treatment is 42mN / m;

[0141] Preparation of antibacterial contact layer:

[0142] (a) Mix 60 parts of waterborne polyurethane emulsion, 10 parts of nano zinc oxide (ZnO), 1.5 parts of dispersant and 25 parts of deionized water until homogeneous to obtain an antibacterial spray coating.

[0143] (ii) The antibacterial coating is evenly sprayed onto the matte surface that has been corona treated, then dried with hot air at 70°C for 2 minutes to evaporate and remove moisture. After curing, an antibacterial contact layer is obtained.

[0144] The total thickness of the heat-sealing film is 65μm, of which the thickness of the matte surface layer is 62μm and the thickness of the antibacterial contact layer dry film is 3μm.

[0145] Comparative Example 4

[0146] The matting agent is made by mixing modified silica powder with a pore volume of 0.7 mL / g (particle size of 3 μm) and cross-linked styrene-acrylate microspheres (particle size of 0.7 μm), and then subjecting the mixture to ultrasonic vibration for 30 min to couple the pores, forming a porous composite carrier, which is then used as the matting agent.

[0147] Modified silica powder is obtained by modifying silica powder with silane. The specific modification process is as follows:

[0148] (a) Mix ethanol and deionized water (mass ratio of ethanol to deionized water is 0.2:1), add glacial acetic acid to adjust the pH of the mixture to 5.0, add 3.5wt% KH-570 based on the mass of silica powder, stir at room temperature for 20min, and the silane is fully hydrolyzed to generate silanol to obtain the hydrolysate.

[0149] (ii) Add silica powder to the hydrolysate, stir at high speed for 450 rpm, prepare a slurry with a solid content of 30%, gradually raise the temperature to 75°C, and keep it at the temperature while stirring for 2 hours;

[0150] (iii) The slurry after reaction was filtered by plate and frame filter press, washed twice with anhydrous ethanol to remove unreacted free silane, the filter cake was dried at 115°C, and then pulverized by air jet through a 370-mesh sieve to obtain modified silica powder.

[0151] The preparation process of antibacterial granules is as follows:

[0152] (a) Select fresh, mold-free rosemary leaves, mint leaves, papaya leaves, and sesame leaves (the mass ratio of rosemary leaves, mint leaves, papaya leaves, and sesame leaves is 1:0.2:0.6:0.8), wash to remove surface impurities, cut into 4mm fragments, and use a freeze-thaw cycle process for osmotic pressure membrane breaking treatment. Repeat the freeze-thaw cycle 3 times to obtain pretreated plant leaf material; the single freezing condition is -20℃ and incubation for 30min, and the single thawing is natural thawing at room temperature;

[0153] (ii) The pretreated plant leaf material was added to a sodium dodecyl sulfate aqueous solution and subjected to constant temperature stirring and extraction for 18 hours; wherein the sodium dodecyl sulfate aqueous solution had a mass concentration of 0.8 wt%, a material-to-liquid ratio of 1:25, and a treatment temperature of 37℃.

[0154] (iii) Take out the processed plant leaf material, repeatedly soak and rinse it with deionized water until there is no foam residue in the rinse water, and then rinse it with Tris-HCl buffer to remove residual sodium dodecyl sulfate and intracellular dissolution impurities to obtain plant leaf pre-processed material.

[0155] (iv) The plant leaf pre-made material is immersed in the antibacterial extract concentrate of Artemisia argyi and a vacuum-assisted impregnation process is adopted. The process parameters of vacuum-assisted impregnation are: vacuum degree -0.08MPa, impregnation temperature 30℃, impregnation time 3h, stirring speed 100r / min throughout the process, and solid-liquid separation is carried out after stirring. The solid material is taken to obtain the wet antibacterial material loaded with active components.

[0156] (v) The wet antibacterial material was vacuum freeze-dried at a vacuum degree of 35 Pa and a cold trap temperature of -45 °C for 10 h. After drying, it was gently pulverized and passed through a 150-mesh sieve to obtain antibacterial particles.

[0157] The preparation method of the antibacterial extract concentrate of Artemisia argyi is as follows: dried Artemisia argyi leaves are mixed with an ethanol aqueous solution with a volume fraction of 70% and a material-to-liquid ratio of 1:20. The mixture is extracted under constant temperature reflux for 1.5 hours, filtered and collected, and concentrated under reduced pressure until the solid content is 20% to obtain the antibacterial extract concentrate of Artemisia argyi.

[0158] Preparation of matte surface layer:

[0159] (a) Add 50 parts of dried PBAT and 30 parts of PLA into a high-speed mixer, and add 2.5 parts of compatibilizer, 5 parts of matting powder, 0.6 parts of oleic acid amide and 0.4 parts of antioxidant 1010 in sequence. Mix in a closed container, control the mixing speed at 1000 r / min, the mixing temperature at 45℃, and stir at high speed for 10 min to make the powder additives and resin matrix evenly dispersed to obtain a homogeneous matting surface premix.

[0160] (ii) The matte surface premix is ​​fed into a twin-screw extruder for melt plasticization, extrusion granulation to obtain matte surface masterbatch, and then the obtained masterbatch is fed into a cast film extruder with a casting die temperature of 175℃ to prepare a matte surface; the side of the matte surface to be sprayed is subjected to corona treatment, and the surface tension after corona treatment is 42mN / m;

[0161] Preparation of antibacterial contact layer:

[0162] (a) Mix 60 parts of waterborne polyurethane emulsion, 10 parts of antibacterial particles, 1.5 parts of dispersant and 25 parts of deionized water until homogeneous to obtain an antibacterial spray coating.

[0163] (ii) The antibacterial coating is evenly sprayed onto the matte surface that has been corona treated, then dried with hot air at 70°C for 2 minutes to evaporate and remove moisture. After curing, an antibacterial contact layer is obtained.

[0164] The total thickness of the heat-sealing film is 65μm, of which the thickness of the matte surface layer is 62μm and the thickness of the antibacterial contact layer dry film is 3μm.

[0165] Performance testing

[0166] (i) The biodegradable heat-sealing films prepared by the methods in Examples 1-3 and Comparative Examples 1-4 were tested according to the methods in QB / T2358 "Test Method for Heat Seal Strength of Plastic Film Packaging Bags";

[0167] Test conditions:

[0168] Sample dimensions: Width: 15mm, Length: 100mm;

[0169] Heat sealing: Standardized temperature, pressure, and time for heat sealing;

[0170] Test: The tensile testing machine was used to peel the material at a speed of 300 mm / min, and the maximum force was recorded;

[0171] Results: expressed in N / 15mm;

[0172] The test results are shown in Table 1.

[0173] Table 1

[0174]

[0175] As can be seen from Table 1, the heat-sealing strength of the biodegradable heat-sealing films prepared in Examples 1-3 of this invention is superior to that in Comparative Examples 1-4. Among them, Example 2 achieved a heat-sealing strength of 2.3 N / 15 mm, exhibiting the best heat-sealing performance. This indicates that the formulation and preparation process of this invention can effectively improve the heat-sealing fusion effect of the biodegradable heat-sealing film, enhance the peel resistance of the seal, and reduce the risk of cracking and leakage at the heat-sealed area of ​​the packaging bag.

[0176] (ii) The biodegradable heat-sealing films prepared by the methods in Examples 1-3 and Comparative Examples 1-4 were tested according to the methods in GB / T19277.1 "Determination of the final aerobic biodegradability of materials under controlled composting conditions by measuring carbon dioxide released - Part 1: General method".

[0177] Test conditions:

[0178] Environment: Controlled composting conditions with a temperature of 58±2℃ and a humidity of 55±5%;

[0179] Period: 28 days;

[0180] Principle: Measure the amount of CO2 released and calculate the biodegradation rate;

[0181] The test results are shown in Table 2.

[0182] Table 2

[0183]

[0184] As can be seen from Table 2, the biodegradable heat-sealing films prepared in Examples 1-3 of the present invention have better 28-day biodegradation rates than those in Comparative Examples 1-4. Among them, the 28-day biodegradation rate of Example 2 can reach 65%, which is the best degradation performance. This proves that the formulation and preparation process of the present invention can improve the microbial degradability of materials, accelerate the mineralization and decomposition of polymer matrix in composting environment, and reduce the risk of environmental residues after disposal.

[0185] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A biodegradable antibacterial matte heat-sealable film, characterized in that, The biodegradable antibacterial matte heat-sealing film is composed of a matte surface layer and an antibacterial contact layer; the total thickness of the heat-sealing film is 25-80μm, of which the thickness of the matte surface layer is 22-75μm and the dry film thickness of the antibacterial contact layer is 1-5μm. The matte surface layer is obtained by casting a matte surface layer masterbatch, which is made from the following raw materials in parts by weight: 40-55 parts PBAT, 20-35 parts PLA, 1.5-3 parts compatibilizer, 3-8 parts matting powder, 0.3-0.8 parts oleamide, and 0.2-0.5 parts antioxidant 1010; The antibacterial contact layer is obtained by spraying a water-based antibacterial spray coating onto a matte surface treated with corona and then drying and curing it; the water-based antibacterial spray coating is made from the following raw materials in parts by weight: 40-70 parts water-based polyurethane emulsion, 5-15 parts antibacterial particles, 0.5-2 parts dispersant and 20-30 parts deionized water.

2. The biodegradable antibacterial matte heat-sealing film according to claim 1, characterized in that, The matting powder is made by mixing modified silica powder with a pore volume of 0.6-0.9 mL / g and cross-linked styrene-acrylate microspheres, followed by ultrasonic vibration for 20-40 minutes to couple the pores and form a porous composite carrier, which is then used as the matting powder.

3. The biodegradable antibacterial matte heat-sealable film according to claim 2, characterized in that, The silica powder with a pore volume of 0.6-0.9 mL / g has a particle size of 2-4.5 μm; the cross-linked styrene-acrylate microspheres have a particle size of 0.5-0.8 μm.

4. The biodegradable antibacterial matte heat-sealable film according to claim 2, characterized in that, The modified silica powder is obtained by modifying silica powder with silane. The specific modification process is as follows: (a) Mix ethanol and deionized water, add glacial acetic acid to adjust the pH of the mixture to 4.5-5.5, add 2.5-5wt% KH-570 based on the mass of silica powder, stir at room temperature for 15-25 min, and the silane will be fully hydrolyzed to generate silanol to obtain the hydrolysate. (ii) Add silica powder to the hydrolysate, stir at high speed 300-600 rpm, prepare a slurry with a solid content of 25-35%, gradually raise the temperature to 70-80℃, and keep it at the temperature while stirring for 1.5-2.5 hours; (iii) The slurry after reaction is filtered by plate and frame filter press, washed 2-3 times with anhydrous ethanol to remove unreacted free silane, the filter cake is dried at 105-120℃, and then air-jet pulverized through a 325-400 mesh sieve to obtain modified silica powder.

5. The biodegradable antibacterial matte heat-sealing film according to claim 4, characterized in that, The mass ratio of ethanol to deionized water is 0.2:

1.

6. The biodegradable antibacterial matte heat-sealable film according to claim 1, characterized in that, The preparation process of the antibacterial particles is as follows: (a) Select fresh, mold-free mugwort leaves, mint leaves, papaya leaves and sesame leaves, wash to remove surface impurities, cut into 2-5mm fragments, and use a freeze-thaw cycle process to perform osmotic pressure membrane breaking treatment. Repeat the freeze-thaw cycle 2-3 times to obtain pretreated plant leaf material; the single freezing condition is -20℃ and heat preservation for 30min, and the single thawing is natural thawing at room temperature; (ii) Add the pretreated plant leaf material to a sodium dodecyl sulfate aqueous solution and perform constant temperature stirring extraction for 12-24 hours; wherein the mass concentration of the sodium dodecyl sulfate aqueous solution is 0.5-1wt%, the material-liquid ratio is 1:20-30, and the treatment temperature is 35-40℃. (iii) Take out the processed plant leaf material, repeatedly soak and rinse it with deionized water until there is no foam residue in the rinse water, and then rinse it with Tris-HCl buffer to remove residual sodium dodecyl sulfate and intracellular dissolution impurities to obtain plant leaf pre-processed material. (iv) The plant leaf pre-made material is immersed in the concentrated antibacterial extract of Artemisia argyi and a vacuum-assisted impregnation process is adopted. The process parameters of vacuum-assisted impregnation are: vacuum degree -0.06~-0.09MPa, impregnation temperature 25-35℃, impregnation time 2-4h, stirring speed 60-120r / min throughout the process, and solid-liquid separation is carried out after stirring. The solid material is taken to obtain the wet antibacterial material loaded with active components. (v) The wet antibacterial material is vacuum-frozen for 8-12 hours at a vacuum degree of 10-50 Pa and a cold trap temperature of -40 to -55℃. After drying, it is gently pulverized and passed through an 80-200 mesh sieve to obtain antibacterial particles.

7. The biodegradable antibacterial matte heat-sealable film according to claim 6, characterized in that, The preparation method of the antibacterial extract concentrate of Artemisia argyi is as follows: dried Artemisia argyi is mixed with an ethanol aqueous solution for extraction, the volume fraction of the ethanol aqueous solution is 60-80%, the material-liquid ratio of dried Artemisia argyi to ethanol aqueous solution is 1:15-1:25, the extraction is carried out under constant temperature reflux for 1-2 hours, the extract is collected by filtration, and concentrated under reduced pressure until the solid content is 15-25% to obtain the antibacterial extract concentrate of Artemisia argyi.

8. The biodegradable antibacterial matte heat-sealable film according to claim 6, characterized in that, The mass ratio of the mugwort leaves, peppermint leaves, papaya leaves, and sesame leaves is 1:0.2:0.6:0.

8.

9. A method for preparing a biodegradable antibacterial matte heat-sealable film according to any one of claims 1-8, characterized in that, Includes the following steps: Preparation of matte surface layer: (a) Put the dried PBAT and PLA into a high-speed mixer, add compatibilizer, matting powder, oleic acid amide and antioxidant 1010 in sequence, mix in a closed container, control the mixing speed to 800-1200 r / min, the mixing temperature to 40-50℃, and stir at high speed for 8-12 min to make the powder additives and resin matrix evenly dispersed to obtain a homogeneous matting surface premix. (ii) The matte surface premix is ​​fed into a twin-screw extruder for melt plasticization, extrusion granulation to obtain matte surface masterbatch, and then the obtained masterbatch is fed into a cast film extruder with a casting die temperature of 160-185℃ to prepare a matte surface; the side of the matte surface to be coated is subjected to corona treatment, and the surface tension after corona treatment is ≥42mN / m; Preparation of antibacterial contact layer: (a) Mix waterborne polyurethane emulsion, antibacterial particles, dispersant and deionized water until homogeneous to obtain antibacterial spray coating; (ii) The antibacterial coating is evenly sprayed onto the matte surface that has been corona treated, then dried with hot air at 60-80℃ for 1-3 minutes to evaporate and remove moisture. After curing, an antibacterial contact layer is obtained.

Images