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

Abstract

The application discloses a preparation method of a high-barrier film with slow-release antibacterial function, and selects polylactic acid with specific molecular weight and crystallinity as a capsule wall of microcapsules to wrap antibacterial liquid, then a barrier layer liquid containing the antibacterial microcapsules is coated on a substrate to form a film with high barrier and slow-release antibacterial effect. The thickness of the microcapsule wall and the diameter of the antibacterial liquid are accurately controlled, the degradation rate of the polylactic acid is controlled, the antibacterial agent is slowly released at a certain rate, the long-time sustained release of the antibacterial agent in the film is realized, the stability and durability of the antibacterial film are ensured, and the problems of low antibacterial stability and durability of the existing microcapsule antibacterial film are solved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of high polymer materials, and more particularly relates to a preparation method of a high-barrier film with slow-release antibacterial function. BACKGROUND

[0002] With the continuous progress of modern science and technology and the increasing demand for the quality of life, antibacterial materials are increasingly widely used in daily life. Traditional antibacterial methods mostly use additive antibacterial liquid, that is, antibacterial agents are directly added to the material matrix. However, the antibacterial film prepared in this way is difficult to meet the long-term antibacterial demand due to the problems of easy migration and easy failure of the antibacterial agent.

[0003] Microcapsule technology is to completely cover the core material with various natural or synthetic polymer compounds (wall or outer phase), and then gradually release the function of the target material again through some external stimulation or slow release. In the antibacterial film, microcapsules with antibacterial substances as the core material can be added to maintain the long-term antibacterial demand of the film by releasing the antibacterial substances inside the microcapsules. How to ensure the long-term release of the antibacterial agent in the microcapsule is the key to maintaining the long-term stability and persistent antibacterial property of the film.

[0004] In CN114773799B, a slow-release antibacterial microcapsule composite biodegradable fresh-keeping film is prepared by combining essential oils with antibacterial activity, bactericidal active polyhexamethylene biguanide hydrochloride, and cellulose nanocrystals with barrier properties to prepare microcapsules, and combining biodegradable resins, lubricants, and antioxidants to obtain a slow-release antibacterial microcapsule composite biodegradable fresh-keeping film. Although this method realizes antibacterial, bactericidal, and barrier properties of the fresh-keeping film through the slow-release effect of the microcapsules, the antibacterial effect of the antibacterial film prepared by this method can only be maintained for a few days, and the antibacterial stability and persistence are low, which makes it difficult to ensure the long-term antibacterial effect of the film. SUMMARY

[0005] To overcome the problems of low antibacterial stability and persistence of the existing microcapsule antibacterial film, the present application provides a preparation method of a high-barrier film with slow-release antibacterial function.

[0006] The present application is achieved by the following technical solutions:

[0007] A preparation method of a high-barrier film with slow-release antibacterial function, comprising the following steps:

[0008] S1. Preparing antibacterial microcapsules;

[0009] The polylactic acid with a molecular weight of 5000-15000 and a crystallinity of 35-40% is dissolved in an organic solvent, then an antibacterial agent is added and stirred uniformly to obtain a mixed solution, and the mixed solution is atomized and granulated to obtain antibacterial microcapsules with an antibacterial liquid diameter of 5-10 microns and a polylactic acid wall thickness of 1-5 microns.

[0010] S2. Prepare a high-barrier film with slow-release antibacterial function;

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

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

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

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

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

[0016] Further, in the spray drying process, the inlet air temperature of the spray dryer is 120-160℃, the higher the inlet air temperature, the thicker the capsule wall, and the outlet air temperature is 60-90℃, mainly for drying the granules.

[0017] Further, in the spray drying process, the centrifugal atomizer has a rotation speed of 26000-28000 rpm, the higher the rotation speed, the smaller the droplet diameter.

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

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

[0020] Further, the coating liquid further includes one or more of a nano-filler, a defoaming agent, and a leveling agent.

[0021] Further, the organic solvent in S1 is N-methyl pyrrolidone, and the solvent in S2 is deionized water.

[0022] Further, the substrate includes PET or paper with a thickness of 20-300 microns.

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

[0024] The application adopts polylactic acid as the microcapsule wall, the protective film can prevent the antibacterial agent from being released rapidly in a short time, and the application utilizes the degradability of polylactic acid, 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 application realizes the sustained release of the antibacterial agent in a long period of time by precisely controlling the thickness of the microcapsule wall and the diameter of the antibacterial liquid, and ensures the stability and durability of the antibacterial effect. After testing, the high barrier film with slow-release antibacterial function prepared by the application can still achieve the initial antibacterial performance after one year.

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

[0026] Figure 1 is a structural schematic diagram of a high barrier film with slow-release antibacterial function according to the application;

[0027] Among them, ① is the base material, ② is the barrier layer, ③ is the antibacterial liquid, and ④ is the capsule wall.

[0028] Figure 2 is a microcapsule picture. DETAILED DESCRIPTION

[0029] The following examples are further explained and illustrated, but the specific examples do not have any form of limitation on the application. If not specifically indicated, the methods and devices used in the examples are conventional methods and devices in the art, and the raw materials used are conventional commercially available raw materials.

[0030] Example 1

[0031] The embodiment provides a preparation method of a high barrier film with slow-release antibacterial function, and the steps include:

[0032] S1. Preparing antibacterial microcapsules;

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

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

[0035] S2. Preparing a high-barrier film with slow-release antibacterial function;

[0036] The water-based polyurethane resin with a solid content of 40wt%, nano-silicon dioxide, defoaming agent, leveling agent, dispersant, antibacterial microcapsules and deionized water are mixed to obtain a coating liquid, wherein the content of each substance is water-based polyurethane resin 30wt%, nano-silicon dioxide 10wt%, defoaming agent 0.3wt%, leveling agent 0.5wt%, dispersant 1wt%, antibacterial microcapsules 6wt%, and the rest is water.

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

[0038] Example 2

[0039] The present embodiment provides a method for preparing a high-barrier film with slow-release antibacterial function, comprising the following steps:

[0040] S1. Preparing antibacterial microcapsules;

[0041] The 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-methyl pyrrolidone to prepare an 8% polylactic acid solution, and then 20% of an antibacterial agent is added and stirred uniformly to obtain a mixed solution, wherein the antibacterial agent comprises Zn(CH3COO)21.5wt%, AgNO30.3wt% and deionized water 98.2wt%.

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

[0043] S2. Preparing a high-barrier film with slow-release antibacterial function;

[0044] The water-based polyurethane resin with a solid content of 40wt%, nano-silica, defoaming agent, leveling agent, dispersant, antibacterial microcapsule and deionized water are mixed to obtain a coating liquid, wherein the content of each substance is water-based polyurethane resin 30wt%, nano-silica 10wt%, defoaming agent 0.4wt%, leveling agent 0.5wt%, dispersant 1wt%, antibacterial microcapsule 10wt%, and the rest is water.

[0045] The coating liquid with a thickness of 10-12μm is coated on a 75μm PET substrate by micro-concave coating method, and a water-based barrier layer is formed after heat curing at 120℃, thereby obtaining a high-barrier film with slow-release antibacterial function.

[0046] Example 3

[0047] The present embodiment provides a preparation method of a high-barrier film with slow-release antibacterial function, and the steps include:

[0048] S1. Preparing antibacterial microcapsules;

[0049] The polylactic acid with a melting point of 180-200℃, a molecular weight of 5000-15000 and a crystallinity of 40% is dissolved in N-methyl pyrrolidone to prepare a 5% polylactic acid solution, and then 20% of an antibacterial agent is added and stirred uniformly to obtain a mixed solution, wherein the antibacterial agent includes Zn(CH3COO)2 2wt% and deionized water 98wt%.

[0050] The mixed solution is further sprayed and atomized, the inlet air temperature of the spray dryer is 160℃, the outlet air temperature is 90℃, the rotating speed of the centrifugal atomizer is 26000rpm, the average diameter of the antibacterial solution is controlled to be 10μm, and the average wall thickness of the polylactic acid is controlled to be 5μm, thereby obtaining slow-release antibacterial microcapsules with a diameter size distribution of 15-20μm after drying and screening.

[0051] S2. Preparing a high-barrier film with slow-release antibacterial function;

[0052] The water-based polyurethane resin with a solid content of 40wt%, nano-silica, defoaming agent, leveling agent, dispersant, antibacterial microcapsule and deionized water are mixed to obtain a coating liquid, wherein the content of each substance is water-based polyurethane resin 30wt%, nano-silica 10wt%, defoaming agent 0.4wt%, leveling agent 0.5wt%, dispersant 1wt%, antibacterial microcapsule 8wt%, and the rest is water.

[0053] The coating liquid with a thickness of 10-12μm is coated on a 75μm PET substrate by micro-concave coating method, and a water-based barrier layer is formed after heat curing at 120℃, thereby obtaining a high-barrier film with slow-release antibacterial function.

[0054] Example 4

[0055] The embodiment provides a preparation method of a high-barrier film with slow-release antibacterial function, and steps include the following:

[0056] S1. Preparing antibacterial microcapsules;

[0057] Polylactic acid with a melting point of 180-200 DEG C, a molecular weight of 5000-15000 and a crystallinity of 40% is dissolved in N-methyl pyrrolidone to prepare a 5% polylactic acid solution, then 15% antibacterial agent is added and stirred uniformly to obtain a mixed solution, wherein the antibacterial agent comprises 0.5wt% of AgNO3, 1wt% of Zn(CH3COO)2 and 98.5wt% of deionized water.

[0058] The mixed solution is further sprayed and atomized, the inlet air temperature of a spray dryer is 160 DEG C, the outlet air temperature is 90 DEG C, the rotating speed of a centrifugal atomizer is 26000 rpm, the antibacterial microcapsules with an average diameter of 10 microns and an average wall thickness of 5 microns are controlled, and after drying, the slow-release antibacterial microcapsules with a diameter size distribution of 15-20 microns are obtained through screening.

[0059] S2. Preparing a high-barrier film with slow-release antibacterial function;

[0060] The water-based polyurethane resin with a solid content of 40wt%, nanosilica, defoaming agent, leveling agent, dispersant and antibacterial microcapsules are mixed with deionized water to obtain a coating liquid, wherein the content of each substance is 25wt% of the water-based polyurethane resin, 8wt% of nanosilica, 0.2wt% of defoaming agent, 0.3wt% of leveling agent, 0.5wt% of dispersant and 15wt% of antibacterial microcapsules, and the rest is water.

[0061] The coating liquid with a thickness of 16-18 microns is coated on a 75-micron PET substrate in a micro-concave coating mode, and a water-based barrier layer is formed after heat curing at 130 DEG C, thereby obtaining a high-barrier film with slow-release antibacterial function.

[0062] Comparative Example 1

[0063] The embodiment provides a preparation method of a high-barrier film, and steps include the following:

[0064] The water-based polyurethane resin with a solid content of 40wt%, nanosilica, defoaming agent, leveling agent and dispersant are mixed with deionized water to obtain a coating liquid, wherein the content of each substance is 32wt% of the water-based polyurethane resin, 11wt% of nanosilica, 0.3wt% of defoaming agent, 0.5wt% of leveling agent and 1wt% of dispersant, and the rest is water. The coating liquid with a thickness of 10-12 microns is coated on a 75-micron PET substrate in a micro-concave coating mode, and a water-based barrier layer is formed after heat curing at 120 DEG C, thereby obtaining a barrier film.

[0065] Comparative Example 2

[0066] The embodiment provides a preparation method of an antibacterial barrier film, and steps include the following:

[0067] The water-based polyurethane resin with a solid content of 40 wt%, nanosilica, a defoaming agent, a leveling agent, a dispersing agent, an antibacterial liquid and deionized water are mixed to obtain a coating liquid, wherein the content of each substance is as follows: the water-based polyurethane resin is 30 wt%, the nanosilica is 10 wt%, the defoaming agent is 0.4 wt%, the leveling agent is 0.5 wt%, the dispersing agent is 1 wt%, the antibacterial liquid is 10 wt%, and the rest is water. The antibacterial liquid comprises Zn(CH3COO)2 1.5 wt%, AgNO3 0.3 wt% and deionized water 98.2 wt%. The coating liquid with a thickness of 16-18 μm is coated on a 75 μm PET substrate by a micro-concave coating method, and an aqueous barrier layer is formed after heat curing at 120 DEG C, so that the high-barrier film with the antibacterial function is obtained.

[0068] Comparative Example 3

[0069] The embodiment provides a preparation method of an antibacterial barrier film, and steps include the following:

[0070] The water-based polyurethane resin with a solid content of 40 wt%, nanosilica, a defoaming agent, a leveling agent, a dispersing agent, an antibacterial liquid and deionized water are mixed to obtain a coating liquid, wherein the content of each substance is as follows: the water-based polyurethane resin is 30 wt%, the nanosilica is 10 wt%, the defoaming agent is 0.4 wt%, the leveling agent is 0.5 wt%, the dispersing agent is 1 wt%, the antibacterial liquid is 10 wt%, and the rest is water. The antibacterial liquid comprises Zn(CH3COO)2 1.5 wt%, AgNO3 0.3 wt% and deionized water 98.2 wt%. The coating liquid with a thickness of 16-18 μm is coated on a 75 μm PET substrate by a micro-concave coating method, and an aqueous barrier layer is formed after heat curing at 120 DEG C, so that the high-barrier film with the antibacterial function is obtained.

[0071] Comparative Example 4

[0072] The embodiment provides a preparation method of an antibacterial barrier film, and steps include the following:

[0073] S1. Preparing an antibacterial microcapsule;

[0074] The polylactic acid with a melting point of 160-180 DEG C, a molecular weight of 5000-15000 and a crystallinity of 25% is dissolved in N-methyl pyrrolidone to prepare a 10% polylactic acid solution, and then 18% antibacterial agent is added and stirred uniformly to obtain a mixed solution, wherein the antibacterial agent comprises Zn(CH3COO)2 2 wt%, AgNO3 0.2 wt% and deionized water 97.8 wt%.

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

[0076] S2. Preparing the antibacterial barrier film;

[0077] The water-based polyurethane resin with a solid content of 40wt%, nano-silicon dioxide, defoaming agent, leveling agent, dispersant, antibacterial microcapsules, and deionized water are mixed to obtain a coating liquid, wherein the content of each substance is 30wt% of the water-based polyurethane resin, 10wt% of nano-silicon dioxide, 0.3wt% of the defoaming agent, 0.5wt% of the leveling agent, 1wt% of the dispersant, 6wt% of the antibacterial microcapsules, and the rest is water.

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

[0079] Comparative Example 5

[0080] The present embodiment provides a method for preparing an antibacterial barrier film, and the steps include:

[0081] S1. Preparing the antibacterial microcapsules;

[0082] The 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-methyl pyrrolidone to prepare an 8% polylactic acid solution, and then 20% of an antibacterial agent is added and stirred uniformly to obtain a mixed solution, wherein the antibacterial agent includes 1.5wt% of Zn(CH3COO)2, 0.3wt% of AgNO3, and 98.2wt% of deionized water.

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

[0084] S2. Preparing the antibacterial barrier film;

[0085] The water-based polyurethane resin with a solid content of 40wt%, nano-silicon dioxide, defoaming agent, leveling agent, dispersant, antibacterial microcapsules, and deionized water are mixed to obtain a coating liquid, wherein the content of each substance is 30wt% of the water-based polyurethane resin, 10wt% of nano-silicon dioxide, 0.3wt% of the defoaming agent, 0.5wt% of the leveling agent, 1wt% of the dispersant, 10wt% of the antibacterial microcapsules, and the rest is water.

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

[0087] Comparative Example 6

[0088] The present example provides a method for preparing an antibacterial barrier film, comprising the steps of:

[0089] S1. Preparing 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-methyl pyrrolidone to prepare a 5% polylactic acid solution, and then 20% of an antibacterial agent is added and stirred uniformly to obtain a mixed solution, wherein the antibacterial agent comprises Zn(CH3COO)2 2wt%, and deionized water 98wt%.

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

[0092] S2. Preparing an antibacterial barrier film;

[0093] A water-based polyurethane resin with a solid content of 40wt%, nano-silicon dioxide, a defoaming agent, a leveling agent, a dispersing agent, antibacterial microcapsules and deionized water are mixed to obtain a coating liquid, wherein the content of each substance is water-based polyurethane resin 30wt%, nano-silicon dioxide 10wt%, defoaming agent 0.4wt%, leveling agent 0.5wt%, dispersing agent 1wt%, antibacterial microcapsules 8wt%, and the rest is water.

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

[0095] Comparative Example 7

[0096] The present example provides a method for preparing an antibacterial barrier film, comprising the steps of:

[0097] S1. Preparing 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-methyl pyrrolidone to prepare an 8% polylactic acid solution, and then 18% of an antibacterial agent is added and stirred uniformly to obtain a mixed solution, wherein the antibacterial agent comprises Zn(CH3COO)2 1wt%, AgNO3 0.5wt%, and deionized water 98.5wt%.

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

[0100] S2. Preparation of the antibacterial barrier film;

[0101] The water-based polyurethane resin with a solid content of 40wt%, nano-silicon dioxide, defoaming agent, leveling agent, dispersant, and antibacterial microcapsules are mixed with deionized water to obtain a coating liquid, wherein the content of each substance is 25wt% of the water-based polyurethane resin, 8wt% of nano-silicon dioxide, 0.2wt% of the defoaming agent, 0.3wt% of the leveling agent, 0.5wt% of the dispersant, and 15wt% of the antibacterial microcapsules, and the rest is water.

[0102] The coating liquid with a thickness of 16-18 μm is coated on a 75 μm PET substrate by micro-concave coating, and an aqueous barrier layer is formed after heat curing at 130°C to obtain the antibacterial barrier film.

[0103] Comparative Example 8

[0104] The present embodiment provides a method for preparing an antibacterial barrier film, and the steps include:

[0105] S1. Preparation of the antibacterial microcapsules;

[0106] The 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-methyl pyrrolidone to prepare a 7% polylactic acid solution, and then 15% of an antibacterial agent is added and stirred uniformly to obtain a mixed solution, wherein the antibacterial agent includes 1.5wt% of Zn(CH3COO)2, 0.3wt% of AgNO3, and 98.2wt% of deionized water.

[0107] The mixed solution is then sprayed and atomized, the inlet temperature of the spray dryer is 170°C, the outlet temperature is 60-90°C, and the centrifugal atomizer rotates at 25500 rpm to obtain the antibacterial microcapsules with an average diameter of 12 μm and an average wall thickness of 3 μm.

[0108] S2. Preparation of the antibacterial barrier film;

[0109] The water-based polyurethane resin with a solid content of 40wt%, nano-silicon dioxide, defoaming agent, leveling agent, dispersant, and antibacterial microcapsules are mixed with deionized water to obtain a coating liquid, wherein the content of each substance is 30wt% of the water-based polyurethane resin, 10wt% of nano-silicon dioxide, 0.4wt% of the defoaming agent, 0.5wt% of the leveling agent, 1wt% of the dispersant, and 10wt% of the antibacterial microcapsules, and the rest is water.

[0110] The coating liquid with a thickness of 10-12 μm is coated on a 75 μm PET substrate by micro-concave coating, and a water-based barrier layer is formed after heat curing at 120°C, thereby obtaining an antibacterial barrier film.

[0111] In the slow-release antibacterial microcapsules prepared in the examples, the actual size of the microcapsules is larger than the ideal diameter due to the presence of air and size deviation of liquid droplets during the preparation process. The oxygen barrier property and antibacterial property of the films of the examples and the comparative examples were detected, wherein the oxygen barrier property of the film was tested according to the standard GB / T 18454-2019, and the antibacterial property of the film was evaluated according to the killing rate of bacteria on the film surface within seven days. The detection results are shown in Table 1.

[0112] Table 1

[0113]

[0114]

[0115] Through comparison of the experimental data, it can be seen from the data of Comparative Examples 2 and 3 that the antibacterial property of the high-barrier film prepared by directly adding the antibacterial liquid gradually decreases after use at room temperature and humidity, and the antibacterial property after one year of use can only reach half of the initial effect. It can be seen from the data of Comparative Examples 4 and 5 that when the crystallinity of PLA is too low, the degradation rate is too fast, and the antibacterial liquid is released too early, and the antibacterial property is greatly reduced after three months; when the crystallinity of PLA is too high, the degradation rate is too slow, which hinders the release of the antibacterial liquid and reduces the initial antibacterial property. It can be seen from the data of Comparative Examples 6 and 7 that when the capsule wall is too thin, the encapsulated antibacterial liquid will be released rapidly in a short time, resulting in strong initial antibacterial effect but short duration; when the capsule wall is too thick, the antibacterial liquid is difficult to release, resulting in insufficient initial antibacterial effect. It can be seen from the data of Comparative Example 8 that when the drop diameter of the antibacterial liquid is too large, the release is uneven, the local concentration is too high when the larger droplets are released, which causes waste and cannot achieve long-term antibacterial effect.

[0116] Obviously, the above examples of the present application are merely exemplary for clearly illustrating the present application, and are not intended to limit the embodiments of the present application. Based on the above description, other different forms of changes or variations can be made by those skilled in the art. Here, it is not necessary and impossible to exhaust all the embodiments. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the claims of the present application.

Claims

1. A method for preparing a high-barrier film with a slow-release antibacterial function, characterized by the steps of The application relates to a preparation method of an antibacterial microcapsule and a high-barrier film with a slow-release antibacterial function. S1. Preparing an antibacterial microcapsule; Polylactic acid with a molecular weight of 5000-15000 and a crystallinity of 35-40% is dissolved in an organic solvent, the concentration of the polylactic acid in the organic solvent is 5-10%, then an antibacterial agent is added and stirred uniformly to obtain a mixed solution, and the mixed solution is atomized and granulated, so that antibacterial liquid with a diameter of 5-10 mu m and polylactic acid wall thickness of 1-5 mu m are obtained after screening, wherein the antibacterial agent in the antibacterial liquid comprises one or more of silver ion antibacterial agents, zinc ion antibacterial agents and quaternary ammonium salt antibacterial agents; S2. Preparing a high-barrier film with a slow-release antibacterial function; Polyurethane, antibacterial microcapsules and a solvent are mixed to obtain a coating liquid, the addition amount of the antibacterial microcapsules is 5-20% of the mass of the polyurethane, the coating liquid with a thickness of 10-12 mu m is coated on a substrate, and the coating liquid is heat-cured on the substrate layer to form a barrier layer, so that the high-barrier film with the slow-release antibacterial function is obtained.

2. The method for preparing the high-barrier membrane with sustained-release antibacterial function according to claim 1, characterized in that, The addition amount of the antibacterial agent is 15-20% of the polylactic acid solution.

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

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

5. The method for preparing the high-barrier membrane with sustained-release antibacterial function according to claim 1, characterized in that, In the atomization and granulation, the rotating speed of the centrifugal atomizer is 26000-28000 rpm.

6. The method for preparing the high-barrier membrane with sustained-release antibacterial function according to claim 1, characterized in that, The coating liquid further comprises one or more of nano fillers, defoaming agents and leveling agents.

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