Preparation method of high-barrier film with slow-release antibacterial function

Abstract

The invention discloses a preparation method of a high-barrier film with a slow-release antibacterial function, which comprises the following steps: selecting polylactic acid with specific molecular weight and crystallinity as a capsule wall of a microcapsule to wrap an antibacterial solution, and then coating a base material with a barrier layer solution containing the antibacterial microcapsule to form a film with high-barrier and slow-release antibacterial effects. The thickness of the wall of the microcapsule and the diameter of the antibacterial liquid are accurately controlled, and the antibacterial agent is slowly released at a certain rate by controlling the degradation rate of polylactic acid, so that long-time continuous release of the antibacterial agent in the film is realized, and the antibacterial stability and durability of the film are ensured; the problems that an existing microcapsule antibacterial film is low in antibacterial stability and durability and the like are solved.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and more specifically, relates to a method for preparing a high-barrier film with slow-release antibacterial function. Background Art

[0002] With the continuous advancement of modern science and technology and people's increasing demands for quality of life, antibacterial materials are increasingly used in daily life. Traditional antibacterial methods mostly use additive antibacterial liquids, that is, adding antibacterial agents directly into the material matrix. The antibacterial films made in this way are difficult to meet the needs of long-term antibacterial due to the problems of easy migration and failure of antibacterial agents.

[0003] Microcapsule technology is to use various natural or synthetic polymer continuous films (walls or external phases) to completely cover the core material, and then gradually make the function of the target object appear again on the outside through certain external stimulation or sustained release. Microcapsules with antibacterial substances as the core material can be added to the antibacterial film, and the long-term antibacterial requirements of the film can be maintained by releasing the antibacterial substances inside the microcapsules. How to ensure the long-term release of antibacterial agents in microcapsules is the key to maintaining the long-term stability and persistent antibacterial properties of the film.

[0004] For example, in CN114773799B, a sustained-release antibacterial microcapsule composite biodegradable fresh-keeping film is disclosed, in which essential oil with antibacterial activity, polyhexamethylene biguanide hydrochloride with bactericidal activity and cellulose nanocrystals with barrier properties are prepared into microcapsules, and then combined with biodegradable resin, lubricant and antioxidant to obtain a sustained-release antibacterial microcapsule composite biodegradable fresh-keeping film. Although this method achieves the antibacterial, bactericidal and barrier properties of the fresh-keeping film through the sustained-release effect of the microcapsules, it can be seen from its application that the antibacterial effect of the antibacterial film prepared by this method can only last for a few days, the antibacterial stability and durability are low, and it is difficult to ensure the long-term antibacterial effect of the film. Summary of the invention

[0005] The present invention provides a method for preparing a high barrier film with slow-release antibacterial function in order to overcome the problems of low antibacterial stability and durability of the existing microcapsule antibacterial film.

[0006] The present invention is achieved through the following technical solutions:

[0007] A method for preparing a high barrier film with sustained-release antibacterial function, comprising:

[0008] S1. Preparation of antibacterial microcapsules;

[0009] Dissolving polylactic acid with a molecular weight of 5000 to 15000 and a crystallinity of 35 to 40% in an organic solvent, then adding an antibacterial agent and stirring evenly to obtain a mixed solution, then atomizing and granulating the mixed solution, and screening to obtain antibacterial microcapsules with an antibacterial liquid diameter of 5 to 10 μm and a polylactic acid wall thickness of 1 to 5 μm;

[0010] S2. Preparation of high barrier film with sustained-release antibacterial function;

[0011] The film-forming polymer, antibacterial microcapsules and solvent are mixed to obtain a coating liquid, which is coated on a substrate with a thickness of 10 to 12 μm. The coating liquid is thermally cured on the substrate layer to form a barrier layer, thereby obtaining a high barrier film with slow-release antibacterial function.

[0012] Furthermore, the concentration of the polylactic acid in the organic solvent is 5% to 10%.

[0013] Furthermore, the amount of the antibacterial liquid added is 15-20% of the polylactic acid solution.

[0014] Furthermore, the content of the antibacterial agent in the antibacterial liquid is 1.5-2.5wt%.

[0015] Furthermore, the antibacterial agent in the antibacterial liquid includes one or more of a silver ion antibacterial agent, a zinc ion antibacterial agent, and a quaternary ammonium salt antibacterial agent.

[0016] Furthermore, the air inlet temperature of the spray dryer in the atomization granulation is 120-160°C, the higher the air inlet temperature, the thicker the capsule wall, and the air outlet temperature is 60-90°C, mainly for drying the granules.

[0017] Furthermore, the rotation speed of the centrifugal atomizer in the atomization granulation is 26000-28000 rpm, and the higher the rotation speed, the smaller the droplet diameter.

[0018] Furthermore, the added amount of the antibacterial microcapsules is 5-20% of the mass of the film-forming polymer.

[0019] Furthermore, the film-forming polymer is a polyurethane resin.

[0020] Furthermore, the coating liquid also includes one or more of nano fillers, defoaming agents, and leveling agents.

[0021] Furthermore, the organic solvent in S1 is N-methylpyrrolidone, and the solvent in S2 is deionized water.

[0022] Furthermore, the substrate includes PET or paper, and has a thickness of 20 to 300 μm.

[0023] Compared with the prior art, the beneficial effects are:

[0024] The present invention uses polylactic acid as the microcapsule wall. The protective film can prevent the antibacterial agent from being quickly released in a short time. At the same time, the present invention uses the degradability of polylactic acid and controls the degradation rate of polylactic acid by controlling the crystallinity of polylactic acid, so that the antibacterial agent is slowly released at a certain rate. The present invention achieves the continuous release of the antibacterial agent over a long period of time by accurately controlling the thickness of the microcapsule wall and the diameter of the antibacterial liquid, thereby ensuring the stability and durability of the antibacterial effect. After testing, the high barrier film with slow-release antibacterial function prepared by the present invention can still achieve the initial antibacterial performance after one year.

[0025] The polylactic acid used in the present invention not only has good biocompatibility and degradability, but also meets environmental protection requirements. The prepared antibacterial film has significant advantages in fields such as food packaging and medical supplies that require long-term antibacterial effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic diagram of the structure of a high barrier membrane with slow-release antibacterial function according to the present invention;

[0027] Among them, ① is the substrate, ② is the barrier layer, ③ is the antibacterial liquid, and ④ is the capsule wall;

[0028] Figure 2 It is a picture of microcapsules. DETAILED DESCRIPTION

[0029] The following is further explained and illustrated in conjunction with the examples, but the specific examples do not limit the present invention in any form. If not specifically stated, the methods and equipment used in the examples are conventional methods and equipment in the art, and the raw materials used are all conventional commercially available raw materials.

[0030] Example 1

[0031] This embodiment provides a method for preparing a high barrier film with a sustained-release antibacterial function, the steps comprising:

[0032] S1. Preparation of antibacterial microcapsules;

[0033] Polylactic acid with a melting point of 180-200°C, a molecular weight of 5000-15000 and a crystallinity of 35% is dissolved in N-methylpyrrolidone to prepare a 10% polylactic acid solution, and then 18% of an antibacterial agent is added and stirred to obtain a mixed solution, wherein the antibacterial agent includes 2wt% zinc acetate (Zn(CH3COO)2), 0.2wt% silver nitrate (AgNO3) and 97.8wt% deionized water.

[0034] The mixed liquid is then sprayed and atomized. The inlet air temperature of the spray dryer is 120°C, the outlet air temperature is 60°C, the speed of the centrifugal atomizer is 28000rpm, and the average diameter of the antibacterial liquid is controlled to be 5μm, and the average wall thickness of the polylactic acid antibacterial microcapsules is 1μm. After screening, sustained-release antibacterial microcapsules with a diameter distribution range of 6 to 12μm are obtained.

[0035] S2. Preparation of high barrier film with sustained-release antibacterial function;

[0036] A coating liquid is obtained by mixing an aqueous polyurethane resin with a solid content of 40wt%, nano-silicon dioxide, a defoamer, a leveling agent, a dispersant, and antibacterial microcapsules with deionized water, wherein the content of each substance is 30wt% of the aqueous polyurethane resin, 10wt% of the nano-silicon dioxide, 0.3wt% of the defoamer, 0.5wt% of the leveling agent, 1wt% of the dispersant, 6wt% of the antibacterial microcapsules, and the rest is water.

[0037] A coating liquid with a thickness of 10 to 12 μm was coated on a 75 μm PET substrate by micro-concave coating, and a water-based barrier layer was formed after thermal curing at 120° C., thereby obtaining a high barrier film with slow-release antibacterial function.

[0038] Example 2

[0039] This embodiment provides a method for preparing a high barrier film with a sustained-release antibacterial function, the steps comprising:

[0040] S1. Preparation of antibacterial microcapsules;

[0041] Polylactic acid with a melting point of 180-200°C, a molecular weight of 5000-15000 and a crystallinity of 38% is dissolved in N-methylpyrrolidone to prepare an 8% polylactic acid solution, and then 20% of an antibacterial agent is added and stirred to obtain a mixed solution, wherein the antibacterial agent includes 21.5wt% of Zn(CH3COO), 0.3wt% of AgNO3 and 98.2wt% of deionized water.

[0042] The mixed liquid is then sprayed and atomized, the inlet air temperature of the spray dryer is 120°C, the outlet air temperature is 60°C, the speed of the centrifugal atomizer is 28000rpm, the average diameter of the antibacterial liquid is controlled to be 5μm, and the average wall thickness of the polylactic acid antibacterial microcapsules is controlled to be 1μm. After drying, the sustained-release antibacterial microcapsules with a diameter size distribution of 6-12μm are obtained by screening.

[0043] S2. Preparation of high barrier film with sustained-release antibacterial function;

[0044] A coating liquid is obtained by mixing an aqueous polyurethane resin with a solid content of 40wt%, nano-silicon dioxide, a defoamer, a leveling agent, a dispersant, and antibacterial microcapsules with deionized water, wherein the content of each substance is 30wt% of the aqueous polyurethane resin, 10wt% of the nano-silicon dioxide, 0.4wt% of the defoamer, 0.5wt% of the leveling agent, 1wt% of the dispersant, 10wt% of the antibacterial microcapsules, and the rest is water.

[0045] A coating liquid with a thickness of 10 to 12 μm was coated on a 75 μm PET substrate by micro-concave coating, and a water-based barrier layer was formed after thermal curing at 120° C., thereby obtaining a high barrier film with slow-release antibacterial function.

[0046] Example 3

[0047] This embodiment provides a method for preparing a high barrier film with a sustained-release antibacterial function, the steps comprising:

[0048] S1. Preparation of antibacterial microcapsules;

[0049] Polylactic acid with a melting point of 180-200°C, a molecular weight of 5000-15000 and a crystallinity of 40% is dissolved in N-methylpyrrolidone to prepare a 5% polylactic acid solution, and then 20% of an antibacterial agent is added and stirred to obtain a mixed solution, wherein the antibacterial agent includes 22wt% Zn(CH3COO) and 98wt% deionized water.

[0050] The mixed liquid is then sprayed and atomized. The inlet air temperature of the spray dryer is 160°C, the outlet air temperature is 90°C, the speed of the centrifugal atomizer is 26000rpm, and the average diameter of the antibacterial liquid is controlled to be 10μm, and the average wall thickness of the polylactic acid antibacterial microcapsules is 5μm. After drying, sustained-release antibacterial microcapsules with a diameter size distribution of 15-20μm are obtained by screening.

[0051] S2. Preparation of high barrier film with sustained-release antibacterial function;

[0052] A coating liquid is obtained by mixing an aqueous polyurethane resin with a solid content of 40wt%, nano-silicon dioxide, a defoamer, a leveling agent, a dispersant, antibacterial microcapsules and deionized water, wherein the content of each substance is 30wt% of the aqueous polyurethane resin, 10wt% of the nano-silicon dioxide, 0.4wt% of the defoamer, 0.5wt% of the leveling agent, 1wt% of the dispersant, 8wt% of the antibacterial microcapsules, and the rest is water.

[0053] A coating liquid with a thickness of 10 to 12 μm was coated on a 75 μm PET substrate by micro-concave coating, and a water-based barrier layer was formed after thermal curing at 120° C., thereby obtaining a high barrier film with slow-release antibacterial function.

[0054] Example 4

[0055] This embodiment provides a method for preparing a high barrier film with a sustained-release antibacterial function, the steps comprising:

[0056] S1. Preparation of antibacterial microcapsules;

[0057] Polylactic acid with a melting point of 180-200°C, a molecular weight of 5000-15000 and a crystallinity of 40% is dissolved in N-methylpyrrolidone to prepare a 5% polylactic acid solution, and then 15% of an antibacterial agent is added and stirred to obtain a mixed solution, wherein the antibacterial agent includes 0.5wt% of AgNO3, 21wt% of Zn(CH3COO) and 98.5wt% of deionized water.

[0058] The mixed liquid is then sprayed and atomized. The inlet air temperature of the spray dryer is 160°C, the outlet air temperature is 90°C, the speed of the centrifugal atomizer is 26000rpm, and the average diameter of the antibacterial liquid is controlled to be 10μm, and the average wall thickness of the polylactic acid antibacterial microcapsules is 5μm. After drying, sustained-release antibacterial microcapsules with a diameter size distribution of 15-20μm are obtained by screening.

[0059] S2. Preparation of high barrier film with sustained-release antibacterial function;

[0060] A coating liquid is obtained by mixing an aqueous polyurethane resin with a solid content of 40wt%, nano-silicon dioxide, a defoamer, a leveling agent, a dispersant, and antibacterial microcapsules with deionized water, wherein the content of each substance is 25wt% of the aqueous polyurethane resin, 8wt% of the nano-silicon dioxide, 0.2wt% of the defoamer, 0.3wt% of the leveling agent, 0.5wt% of the dispersant, 15wt% of the antibacterial microcapsules, and the rest is water.

[0061] A coating liquid with a thickness of 16 to 18 μm was coated on a 75 μm PET substrate by micro-concave coating, and a water-based barrier layer was formed after thermal curing at 130° C., thereby obtaining a high barrier film with slow-release antibacterial function.

[0062] Comparative Example 1

[0063] This embodiment provides a method for preparing a barrier film, the steps comprising:

[0064] A coating liquid is obtained by mixing a waterborne polyurethane resin with a solid content of 40 wt%, nano-silicon dioxide, a defoamer, a leveling agent, a dispersant and deionized water, wherein the content of each substance is 32 wt% of the waterborne polyurethane resin, 11 wt% of the nano-silicon dioxide, 0.3 wt% of the defoamer, 0.5 wt% of the leveling agent, 1 wt% of the dispersant, and the rest is water. The coating liquid with a thickness of 10 to 12 μm is coated on a 75 μm PET substrate by a micro-concave coating method, and a waterborne barrier layer is formed after thermal curing at 120° C. to obtain a barrier film.

[0065] Comparative Example 2

[0066] This embodiment provides a method for preparing an antibacterial barrier film, the steps comprising:

[0067] A coating liquid is obtained by mixing a water-based polyurethane resin with a solid content of 40wt%, nano-silicon dioxide, a defoamer, a leveling agent, a dispersant, an antibacterial liquid and deionized water, wherein the content of each substance is 30wt% of water-based polyurethane resin, 10wt% of nano-silicon dioxide, 0.4wt% of defoamer, 0.5wt% of leveling agent, 1wt% of dispersant, 10wt% of antibacterial liquid, and the rest is water. The antibacterial liquid includes 21.5wt% of Zn(CH3COO), 0.3wt% of AgNO3, and 98.2wt% of deionized water. The coating liquid with a thickness of 16 to 18μm is coated on a 75μm PET substrate by a micro-concave coating method, and a water-based barrier layer is formed after thermal curing at 120°C to obtain a high barrier film with antibacterial function.

[0068] Comparative Example 3

[0069] This embodiment provides a method for preparing an antibacterial barrier film, the steps comprising:

[0070] A coating liquid is obtained by mixing a water-based polyurethane resin with a solid content of 40 wt%, nano-silicon dioxide, a defoamer, a leveling agent, a dispersant, an antibacterial liquid and deionized water, wherein the content of each substance is 35 wt% of water-based polyurethane resin, 10 wt% of nano-silicon dioxide, 0.5 wt% of defoamer, 0.7 wt% of leveling agent, 0.8 wt% of dispersant, 10 wt% of antibacterial liquid, and the rest is water. The antibacterial liquid includes 22 wt% of Zn(CH3COO) and 98 wt% of deionized water. The coating liquid with a thickness of 16 to 18 μm is coated on a 75 μm PET substrate by a micro-concave coating method, and a water-based barrier layer is formed after thermal curing at 130°C to obtain an antibacterial barrier film.

[0071] Comparative Example 4

[0072] This embodiment provides a method for preparing an antibacterial barrier film, the steps comprising:

[0073] S1. Preparation of antibacterial microcapsules;

[0074] Polylactic acid with a melting point of 160-180°C, a molecular weight of 5000-15000 and a crystallinity of 25% is dissolved in N-methylpyrrolidone to prepare a 10% polylactic acid solution, and then 18% of an antibacterial agent is added and stirred to obtain a mixed solution, wherein the antibacterial agent includes 22wt% Zn(CH3COO), 0.2wt% AgNO3 and 97.8wt% deionized water.

[0075] The mixed liquid is then sprayed and atomized, the spray dryer inlet air temperature is 120°C, the outlet air temperature is 60°C, and the centrifugal atomizer speed is 28000rpm, to obtain antibacterial microcapsules with an average diameter of 5 μm for the antibacterial liquid, an average wall thickness of 1 μm for polylactic acid, and a diameter size distribution of 6 to 12 μm.

[0076] S2. Preparation of antibacterial barrier film;

[0077] A coating liquid is obtained by mixing an aqueous polyurethane resin with a solid content of 40wt%, nano-silicon dioxide, a defoamer, a leveling agent, a dispersant, and antibacterial microcapsules with deionized water, wherein the content of each substance is 30wt% of the aqueous polyurethane resin, 10wt% of the nano-silicon dioxide, 0.3wt% of the defoamer, 0.5wt% of the leveling agent, 1wt% of the dispersant, 6wt% of the antibacterial microcapsules, and the rest is water.

[0078] A coating liquid with a thickness of 10 to 12 μm is coated on a 75 μm PET substrate by a micro-concave coating method, and a water-based barrier layer is formed after thermal curing at 120° C. to obtain an antibacterial barrier film.

[0079] Comparative Example 5

[0080] This embodiment provides a method for preparing an antibacterial barrier film, the steps comprising:

[0081] S1. Preparation of antibacterial microcapsules;

[0082] Polylactic acid with a melting point of 185-215°C, a molecular weight of 5000-15000 and a crystallinity of 45% is dissolved in N-methylpyrrolidone to prepare an 8% polylactic acid solution, and then 20% of an antibacterial agent is added and stirred to obtain a mixed solution, wherein the antibacterial agent includes 21.5wt% of Zn(CH3COO), 0.3wt% of AgNO3 and 98.2wt% of deionized water.

[0083] The mixed liquid is then sprayed and atomized, the spray dryer inlet air temperature is 145°C, the outlet air temperature is 80°C, and the centrifugal atomizer speed is 28000rpm, to obtain antibacterial microcapsules with an average diameter of 5 μm for the antibacterial liquid, an average wall thickness of 3 μm for polylactic acid, and a diameter size distribution of 8 to 15 μm.

[0084] S2. Preparation of antibacterial barrier film;

[0085] A coating liquid is obtained by mixing an aqueous polyurethane resin with a solid content of 40wt%, nano-silicon dioxide, a defoamer, a leveling agent, a dispersant, and antibacterial microcapsules with deionized water, wherein the content of each substance is 30wt% of the aqueous polyurethane resin, 10wt% of the nano-silicon dioxide, 0.3wt% of the defoamer, 0.5wt% of the leveling agent, 1wt% of the dispersant, 10wt% of the antibacterial microcapsules, and the rest is water.

[0086] A coating liquid with a thickness of 10 to 12 μm was coated on a 75 μm PET substrate by a micro-concave coating method, and a water-based barrier layer was formed after thermal curing at 120° C. to obtain an antibacterial barrier film.

[0087] Comparative Example 6

[0088] This embodiment provides a method for preparing an antibacterial barrier film, the steps comprising:

[0089] S1. Preparation of antibacterial microcapsules;

[0090] Polylactic acid with a melting point of 180-200°C, a molecular weight of 5000-15000 and a crystallinity of 40% is dissolved in N-methylpyrrolidone to prepare a 5% polylactic acid solution, and then 20% of an antibacterial agent is added and stirred to obtain a mixed solution, wherein the antibacterial agent includes 22wt% Zn(CH3COO) and 98wt% deionized water.

[0091] The mixed liquid is then sprayed and atomized, the spray dryer inlet air temperature is 110°C, the outlet air temperature is 60°C, and the centrifugal atomizer speed is 28000rpm, to obtain antibacterial microcapsules with an average diameter of 5μm, an average wall thickness of polylactic acid of 0.05μm, and a size distribution of 5-10μm.

[0092] S2. Preparation of antibacterial barrier film;

[0093] A coating liquid is obtained by mixing an aqueous polyurethane resin with a solid content of 40wt%, nano-silicon dioxide, a defoamer, a leveling agent, a dispersant, antibacterial microcapsules and deionized water, wherein the content of each substance is 30wt% of the aqueous polyurethane resin, 10wt% of the nano-silicon dioxide, 0.4wt% of the defoamer, 0.5wt% of the leveling agent, 1wt% of the dispersant, 8wt% of the antibacterial microcapsules, and the rest is water.

[0094] A coating liquid with a thickness of 15 to 18 μm was coated on a 75 μm PET substrate by a micro-concave coating method, and a water-based barrier layer was formed after thermal curing at 130° C. to obtain an antibacterial barrier film.

[0095] Comparative Example 7

[0096] This embodiment provides a method for preparing an antibacterial barrier film, the steps comprising:

[0097] S1. Preparation of antibacterial microcapsules;

[0098] Polylactic acid with a melting point of 180-200°C, a molecular weight of 5000-15000 and a crystallinity of 38% is dissolved in N-methylpyrrolidone to prepare an 8% polylactic acid solution, and then 18% of an antibacterial agent is added and stirred to obtain a mixed solution, wherein the antibacterial agent includes 21wt% Zn(CH3COO), 0.5wt% AgNO3 and 98.5wt% deionized water.

[0099] The mixed liquid was then sprayed and atomized, the inlet air temperature of the spray dryer was 170°C, the outlet air temperature was 95°C, and the speed of the centrifugal atomizer was 26000rpm, to obtain antibacterial microcapsules with an average diameter of 10 μm and an average wall thickness of 7 μm for the antibacterial liquid.

[0100] S2. Preparation of antibacterial barrier film;

[0101] A coating liquid is obtained by mixing an aqueous polyurethane resin with a solid content of 40wt%, nano-silicon dioxide, a defoamer, a leveling agent, a dispersant, and antibacterial microcapsules with deionized water, wherein the content of each substance is 25wt% of the aqueous polyurethane resin, 8wt% of the nano-silicon dioxide, 0.2wt% of the defoamer, 0.3wt% of the leveling agent, 0.5wt% of the dispersant, 15wt% of the antibacterial microcapsules, and the rest is water.

[0102] A coating liquid with a thickness of 16 to 18 μm was coated on a 75 μm PET substrate by a micro-concave coating method, and a water-based barrier layer was formed after thermal curing at 130° C. to obtain an antibacterial barrier film.

[0103] Comparative Example 8

[0104] This embodiment provides a method for preparing an antibacterial barrier film, the steps comprising:

[0105] S1. Preparation of antibacterial microcapsules;

[0106] Polylactic acid with a melting point of 180-200°C, a molecular weight of 5000-15000 and a crystallinity of 38% is dissolved in N-methylpyrrolidone to prepare a 7% polylactic acid solution, and then 15% of an antibacterial agent is added and stirred to obtain a mixed solution, wherein the antibacterial agent includes 21.5wt% Zn(CH3COO), 0.3wt% AgNO3 and 98.2wt% deionized water.

[0107] The mixed liquid is then sprayed and atomized, the inlet air temperature of the spray dryer is 170°C, the outlet air temperature is 60-90°C, and the antibacterial microcapsules with an average diameter of 12 μm and an average wall thickness of 3 μm of polylactic acid are obtained through a centrifugal atomizer at 25,500 rpm.

[0108] S2. Preparation of antibacterial barrier film;

[0109] A coating liquid is obtained by mixing an aqueous polyurethane resin with a solid content of 40wt%, nano-silicon dioxide, a defoamer, a leveling agent, a dispersant, and antibacterial microcapsules with deionized water, wherein the content of each substance is 30wt% of the aqueous polyurethane resin, 10wt% of the nano-silicon dioxide, 0.4wt% of the defoamer, 0.5wt% of the leveling agent, 1wt% of the dispersant, 10wt% of the antibacterial microcapsules, and the rest is water.

[0110] A coating liquid with a thickness of 10 to 12 μm was coated on a 75 μm PET substrate by a micro-concave coating method, and a water-based barrier layer was formed after thermal curing at 120° C. to obtain an antibacterial barrier film.

[0111] In the sustained-release antibacterial microcapsules prepared in the examples, due to the deviation of air and droplet size during the preparation process, the actual size of the microcapsules obtained is larger than the diameter under the ideal state. The oxygen barrier properties and antibacterial properties of the films of the examples and comparative examples were tested respectively, wherein the oxygen barrier properties of the films were tested according to the GB / T 18454-2019 standard, and the antibacterial standard of the films was: 10*8CFU / mL Staphylococcus aureus was placed on the surface of the film as the target, and the bacterial killing rate within seven days was observed as the evaluation standard. The test results are shown in Table 1 below:

[0112] Table 1

[0113]

[0114]

[0115] By comparing the experimental data, the high barrier film prepared by directly adding antibacterial liquid in Comparative Examples 2 and 3 gradually decreases its antibacterial performance after use at room temperature and humidity, and the antibacterial performance after one year of use can only reach half of the initial effect. It can be seen from the data in Comparative Examples 4 and 5 that when the crystallinity of PLA is too low, its degradation rate is too fast, the antibacterial liquid wrapped is released in advance, and the antibacterial performance is greatly reduced after three months; when the crystallinity of PLA is too high, its degradation rate is too slow, which hinders the release of the antibacterial liquid and reduces the initial antibacterial performance. It can be seen from the data in Comparative Examples 6 and 7 that when the capsule wall is too thin, the wrapped antibacterial liquid will be quickly released in a short time, resulting in a strong initial antibacterial effect but a short duration; when the capsule wall is too thick, the antibacterial liquid is difficult to release, resulting in an insufficient initial antibacterial effect. It can be seen from the data in Comparative Example 8 that when the droplet diameter of the antibacterial liquid is too large, it will lead to uneven release, and larger droplets will form a local concentration that is too high when released, causing waste, and it is impossible to achieve a long-term antibacterial effect.

[0116] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A method for preparing a high barrier film with sustained-release antibacterial function, characterized in that the steps include: S1. Preparation of antibacterial microcapsules; Dissolving polylactic acid with a molecular weight of 5000 to 15000 and a crystallinity of 35 to 40% in an organic solvent, then adding an antibacterial agent and stirring evenly to obtain a mixed solution, then atomizing and granulating the mixed solution, and screening to obtain antibacterial microcapsules with an antibacterial liquid diameter of 5 to 10 μm and a polylactic acid wall thickness of 1 to 5 μm; S2. Preparation of high barrier film with sustained-release antibacterial function; The film-forming polymer, antibacterial microcapsules and solvent are mixed to obtain a coating liquid, which is coated on a substrate with a thickness of 10 to 12 μm. The coating liquid is thermally cured on the substrate layer to form a barrier layer, thereby obtaining a high barrier film with slow-release antibacterial function.

2. The method for preparing a high barrier film with sustained-release antibacterial function according to claim 1, characterized in that: The concentration of the polylactic acid in the organic solvent is 5% to 10%.

3. The method for preparing a high barrier film with sustained-release antibacterial function according to claim 1, characterized in that: The added amount of the antibacterial liquid is 15-20% of the polylactic acid solution.

4. The method for preparing a high barrier film with sustained-release antibacterial function according to claim 1, characterized in that: The content of the antibacterial agent in the antibacterial liquid is 1.5-2.5wt%.

5. The method for preparing a high barrier film with sustained-release antibacterial function according to claim 1, characterized in that: The antibacterial agent in the antibacterial liquid includes one or more of a silver ion antibacterial agent, a zinc ion antibacterial agent, and a quaternary ammonium salt antibacterial agent.

6. The method for preparing a high barrier film with sustained-release antibacterial function according to claim 1, characterized in that: The air inlet temperature of the spray dryer in the atomization granulation is 120-160°C, and the air outlet temperature is 60-90°C.

7. The method for preparing a high barrier film with sustained-release antibacterial function according to claim 1, characterized in that: The rotation speed of the centrifugal atomizer in the atomization granulation is 26000-28000 rpm.

8. The method for preparing a high barrier film with sustained-release antibacterial function according to claim 1, characterized in that: The added amount of the antibacterial microcapsules is 5-20% of the mass of the film-forming polymer.

9. The method for preparing a high barrier film with sustained-release antibacterial function according to claim 1, characterized in that: The film-forming polymer is a polyurethane resin.

10. The method for preparing a high barrier film with sustained-release antibacterial function according to claim 1, characterized in that: The coating liquid also includes one or more of nano fillers, defoamers, and leveling agents.

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