Dynamic self-repairing type high-toughness bio-based degradable film as well as preparation method and application thereof

Abstract

The invention relates to the field of composite soft plastic packaging, in particular to a dynamic self-repairing type high-toughness bio-based degradable film and a preparation method and application thereof. The film is composed of a lactic acid high polymer, a copolymer of butylene adipate and butylene terephthalate, a compatibilizer, a nucleating agent, a catalyst, an auxiliary agent and an antibacterial agent, the catalyst is formed by mixing a main catalyst and a co-catalyst, the main catalyst comprises any one of zinc acetylacetonate, ferric acetylacetonate, antimony trioxide and zinc oxide, and the co-catalyst comprises any one of zinc acetylacetonate, ferric acetylacetonate, antimony trioxide and zinc oxide. The cocatalyst is selected from any one of triethylamine, triphenylphosphine and aluminum acetylacetonate. The invention provides an effective scheme for solving the core contradiction that the strength, toughness, repairability and controllable degradability of a bio-based material are difficult to consider at the same time, is expected to replace traditional plastics in the fields of high-end environment-friendly packaging, intelligent agricultural mulching films and the like, and has great environmental benefits and industrialization prospects.

Description

Technical Field

[0001] This invention relates to the field of composite flexible plastic packaging, specifically to a dynamic self-healing, high-toughness bio-based biodegradable film, its preparation method, and its application. Background Technology

[0002] Bio-based biodegradable polymers, such as polylactic acid (PLA) and polybutylene adipate terephthalate (PBAT), are considered the preferred environmentally friendly alternatives to traditional petroleum-based plastics (such as polyethylene and polypropylene) due to their renewable sources and compostable degradation properties. However, the overall performance of existing PLA / PBAT-based biodegradable films falls far short of practical application requirements.

[0003] First, in terms of reliability and durability, PLA and PBAT are inherently incompatible. Simple blending easily leads to phase separation, resulting in poor mechanical properties and barrier properties. Although adding compatibilizers, plasticizers, or nucleating agents can improve their processing and mechanical properties to some extent, these modification methods often bring new problems. For example, improving flexibility requires sacrificing strength and modulus, while increasing rigidity may lead to increased brittleness of the material.

[0004] In addition, such materials inevitably develop microscopic scratches and cracks during transportation and use. These damages continue to expand due to stress concentration, which not only significantly reduces the barrier properties of the material, causing premature packaging failure, but also becomes a breakthrough point for microbial erosion, accelerating the aging of the material and the spoilage of the product.

[0005] Current technologies generally lack effective mechanisms to address microscopic damage to materials. Once microcracks develop, their irreversible accumulation directly shortens the product's lifespan. This has become a core bottleneck restricting its widespread adoption, especially in scenarios requiring repeated stress and impact (such as cold chain logistics and fresh food packaging) or long-term outdoor use (such as agricultural mulch films).

[0006] Secondly, the limited functionality also restricts its application scope. For example, in high-humidity environments such as fresh food packaging, microorganisms easily grow on the surface of the material, and most existing biodegradable films do not have active antibacterial functions, thus failing to effectively extend the shelf life of food.

[0007] Finally, the degradation behavior of materials lacks intelligent regulation. Ideal bio-based materials not only need to remain stable during their service life but also degrade rapidly and completely after disposal. However, current technologies struggle to precisely balance performance reliability and degradation issues during use.

[0008] Therefore, improving bio-based biodegradable polymer formulations and developing a new generation of bio-based biodegradable films to overcome the inherent performance defects of PLA / PBAT substrates, while ensuring mechanical, barrier, and transparency properties, and balancing the stability during the service life and the problem of rapid degradation after disposal, are urgent technical problems to be solved. Summary of the Invention

[0009] To address the problems in the prior art, one of the objectives of this invention is to provide a dynamic self-healing, high-toughness bio-based biodegradable film.

[0010] The present invention adopts the following technical solution: A dynamic self-healing, high-toughness, biodegradable film comprising: 20-70 parts by weight of lactic acid polymer (PLA), 20-70 parts by weight of a copolymer of butylene adipate and butylene terephthalate (PBAT), 1-5 parts by weight of compatibilizer, 1-5 parts by weight of nucleating agent, 1-3 parts by weight of catalyst, 0.5-1.0 parts by weight of auxiliary agent, and 1-4 parts by weight of antibacterial agent; wherein the catalyst is composed of a main catalyst and a co-catalyst mixed at a mass ratio of 1:(0.1-0.5), wherein the main catalyst comprises any one or more combinations of zinc acetylacetonate, iron acetylacetonate, antimony trioxide, and zinc oxide, and the co-catalyst is selected from any one of triethylamine, triphenylphosphine, and aluminum acetylacetonate.

[0011] Preferably, the main catalyst is zinc acetylacetonate and the co-catalyst is triethylamine or triphenylphosphine, and the mass ratio of the main catalyst to the co-catalyst is 1: (0.1~0.5).

[0012] Preferably, the melt index of the lactic acid polymer is 3-5 g / 10 min, and the melt index of the copolymer of butylene adipate and butylene terephthalate is 3-5 g / 10 min, as tested according to GB / T 3682-2018.

[0013] Preferably, the compatibilizer is an epoxide or a diol oligomer, wherein the epoxide is epoxidized soybean oil; and the diol oligomer is a diol oligomer containing primary hydroxyl groups at both ends, with a number average molecular weight of 1000-10000, selected from polyether diols and / or polyester diols.

[0014] Preferably, the number-average molecular weight of the diol oligomer is 1000-2000.

[0015] Preferably, the polyether diol is selected from at least one of polyethylene glycol, polytetrahydrofuran, and block copolymers of polyethylene glycol and polytetrahydrofuran, and the polyester diol is selected from any one or a combination of several of the following: polybutanediol, polycaprolactone diol, polyhexanediol, polybutanediol, polysuccinic acid-octanediol, polydecanediol, polyoctanediol, polybutanediol, polyoctanediol, polydecanediol, and polyhexanediol.

[0016] Preferably, the nucleating agent is talc or polyethylene glycol (PEG), the auxiliary agent is a silane coupling agent, and the antibacterial agent is chitosan.

[0017] Preferably, the silane coupling agent is vinylmethyldimethoxysilane, which is used to modify the surface of talc powder to prevent agglomeration.

[0018] Preferably, the thickness of the film is 20~50 μm.

[0019] The second objective of this invention is to provide a method for preparing a dynamic self-healing, high-toughness biodegradable film as described above, comprising the following steps: S1. Weigh out the raw materials in each mass fraction, add them to the granulator, heat and melt them, cool them, and cut them to obtain uniform mixed particles; S2. The mixed particles are dried at 80°C until the moisture content is below 200 ppm; S3. Add the dried mixed particles to the extruder, melt extrude, filter, form with a die, and cool and solidify with a casting roller to obtain the desired film.

[0020] Preferably, the barrel temperature of the granulator is 160~210℃ and the stirring speed is 280~320 r / min.

[0021] Preferably, it also includes any one or more of the following processes: corona treatment, ink printing, and thermal lamination. The composite material used in the thermal lamination process is any one of the following: biaxially oriented polylactic acid film, modified polylactic acid film, and polypropylene carbonate blend modified film.

[0022] The third objective of this invention is to provide the application of the aforementioned dynamic self-healing, high-toughness bio-based biodegradable film in the preparation of functional plastic products, including packaging materials and films, such as food packaging films, agricultural mulch films, seed coatings, grafting wrapping films, electronic device encapsulation films, dressing base films, etc.

[0023] The beneficial effects of this invention are as follows: This invention introduces a specific dual-core dynamic catalytic system into the traditional PLA / PBAT system, enabling the film to trigger a rapid transesterification reaction upon microscopic damage, achieving efficient self-healing and significantly improving its reliability and durability during use. Experiments show that the prepared film achieves an elongation at break of 478% while maintaining a tensile strength of 39.5 MPa, effectively solving the problem of balancing strength and toughness in existing PLA / PBAT blends. Furthermore, under wet conditions, over 90% of microscopic scratches can close within 2 hours, and the mechanical property recovery rate exceeds 97% within 6 hours. This self-healing characteristic significantly improves the reliability of the film during transportation and use, effectively extending its service life.

[0024] Through the synergistic combination of chitosan and a dual-core catalytic system, while ensuring the material's high toughness, high barrier properties, and high transparency, it also endows it with excellent active antibacterial properties (inhibition rates of over 98% against both Escherichia coli and Staphylococcus aureus), and enables the film to exhibit intelligent degradation behavior of "stable during use and rapid disintegration after disposal".

[0025] Experiments show that the film provided by this invention maintains structural stability with a weight loss rate of less than 5% during its service life (approximately 30 days); however, it triggers rapid disintegration upon entering a composting environment, with a biodegradation rate exceeding 88% after 60 days and a degradation half-life of ( (No more than 50 days)

[0026] This invention also enables the film to possess high barrier properties (water vapor transmission rate less than 40 g / m²·day) and high transparency (light transmittance > 92%) through the compounding of components such as nucleating agents and antibacterial agents. Furthermore, the film exhibits excellent surface properties, allowing for direct high-quality printing, and can be combined with other biodegradable materials through composite technology to create more comprehensive packaging solutions.

[0027] This application provides an effective solution to the core contradiction of the difficulty in simultaneously achieving strength, toughness, repairability, and controllable degradation of bio-based materials. It is expected to replace traditional plastics in fields such as high-end environmentally friendly packaging and smart agricultural mulch films, and has significant environmental benefits and industrialization prospects. Detailed Implementation

[0028] The technical solution of the present invention will be described below with reference to embodiments, so that those skilled in the art can understand it.

[0029] Unless otherwise stated, the terms used herein have the meanings commonly understood by those skilled in the art.

[0030] The raw material information used in the examples is as follows: Lactic acid polymer: PT102 produced by Pulis Biotechnology Co., Ltd.; Copolymer of butylene adipate and butylene terephthalate: HF101 produced by Ruian Environmental Protection Materials Branch of Huafeng Group Co., Ltd.; Epoxidized soybean oil: H1147827 produced by Shandong Xiya Chemical Co., Ltd.; Polycaprolactone diol: P50206 from Shanghai Maclean Biochemical Technology Co., Ltd.; Talc: G24973D produced by Shanghai Titan Technology Co., Ltd.; Additive (vinylmethyldimethoxysilane): SCA-V71T manufactured by Nanjing Nengde New Materials Co., Ltd.; Polyethylene glycol: 1085772 from Shanghai Haohong Biomedical Technology Co., Ltd.; Zinc acetylacetone: Z829399 from Shanghai Maclean Biochemical Technology Co., Ltd.; Triphenylphosphine: T104475 from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0031] Example 1

[0032] A biodegradable film comprises: 60 parts by weight of PLA, 30 parts by weight of PBAT, 1 part by weight of epoxidized soybean oil, 2 parts by weight of polycaprolactone diol, 1.5 parts by weight of talc, 1.5 parts by weight of polyethylene glycol, 2 parts by weight of chitosan, 1 part by weight of zinc acetylacetonate, 0.3 parts by weight of triphenylphosphine, and 1 part by weight of silane coupling agent, prepared by a casting process. It is denoted as film S1.

[0033] Example 2

[0034] A biodegradable film comprises: 70 parts by weight of PLA, 20 parts by weight of PBAT, 1 part by weight of epoxidized soybean oil, 2 parts by weight of polycaprolactone diol, 1.5 parts by weight of talc, 1.5 parts by weight of polyethylene glycol, 2 parts by weight of chitosan, 1 part by weight of zinc acetylacetonate, 0.3 parts by weight of triphenylphosphine, and 1 part by weight of silane coupling agent, prepared by a casting process. It is denoted as film S2.

[0035] Example 3

[0036] A biodegradable film comprises: 25 parts by weight of PLA, 65 parts by weight of PBAT, 1 part by weight of epoxidized soybean oil, 2 parts by weight of polycaprolactone diol, 1.5 parts by weight of talc, 1.5 parts by weight of polyethylene glycol, 2 parts by weight of chitosan, 1 part by weight of zinc acetylacetonate, 0.3 parts by weight of triphenylphosphine, and 1 part by weight of silane coupling agent, prepared by a casting process. It is denoted as film S3.

[0037] Example 4

[0038] A biodegradable film comprises: 20 parts by weight of PLA, 20 parts by weight of PBAT, 1 part by weight of epoxidized soybean oil, 2 parts by weight of polycaprolactone diol, 1.5 parts by weight of talc, 1.5 parts by weight of polyethylene glycol, 2 parts by weight of chitosan, 1 part by weight of zinc acetylacetonate, 0.3 parts by weight of triphenylphosphine, and 1 part by weight of silane coupling agent, prepared by a casting process. It is denoted as film S4.

[0039] Example 5

[0040] A biodegradable film comprises: 45 parts by weight of PLA, 45 parts by weight of PBAT, 1 part by weight of epoxidized soybean oil, 2 parts by weight of polycaprolactone diol, 1.5 parts by weight of talc, 1.5 parts by weight of polyethylene glycol, 2 parts by weight of chitosan, 1 part by weight of zinc acetylacetonate, 0.3 parts by weight of triphenylphosphine, and 1 part by weight of silane coupling agent, prepared by a casting process. It is designated as film S5.

[0041] Example 6

[0042] A biodegradable film comprises: 60 parts by weight of PLA, 30 parts by weight of PBAT, 1 part by weight of epoxidized soybean oil, 2 parts by weight of polycaprolactone diol, 1.5 parts by weight of talc, 1.5 parts by weight of polyethylene glycol, 2 parts by weight of chitosan, 1 part by weight of zinc acetylacetonate, 0.1 parts by weight of triphenylphosphine, and 1 part by weight of silane coupling agent, prepared by a casting process. It is designated as film S6.

[0043] Example 7

[0044] A biodegradable film comprises: 60 parts by weight of PLA, 30 parts by weight of PBAT, 1 part by weight of epoxidized soybean oil, 2 parts by weight of polycaprolactone diol, 1.5 parts by weight of talc, 1.5 parts by weight of polyethylene glycol, 2 parts by weight of chitosan, 1.5 parts by weight of iron acetylacetone, 0.75 parts by weight of triphenylphosphine, and 1 part by weight of a silane coupling agent, prepared by a casting process. It is designated as film S7.

[0045] Comparative Example 1

[0046] A biodegradable film comprises 60 parts by mass of PLA and 30 parts by mass of PBAT, prepared by a casting process. It is denoted as film D1.

[0047] Comparative Example 2

[0048] A biodegradable film comprises: 60 parts by weight of PLA, 30 parts by weight of PBAT, 1 part by weight of epoxidized soybean oil, 2 parts by weight of polycaprolactone diol, 1 part by weight of zinc acetylacetonate, and 0.5 parts by weight of silane coupling agent, prepared by a casting process. It is denoted as film D2.

[0049] Comparative Example 3

[0050] A biodegradable film comprises: 62 parts by weight of PLA resin, 30 parts by weight of PBAT resin, 1 part by weight of epoxidized soybean oil, 2 parts by weight of polycaprolactone diol, 1.5 parts by weight of talc, 1.5 parts by weight of polyethylene glycol, 1 part by weight of zinc acetylacetonate, and 1 part by weight of silane coupling agent, prepared by a casting process. It is denoted as film D3.

[0051] Comparative Example 4

[0052] A biodegradable film comprises: 60 parts by weight of PLA resin, 30 parts by weight of PBAT resin, 1 part by weight of epoxidized soybean oil, 2 parts by weight of polycaprolactone diol, 1.5 parts by weight of talc, 1.5 parts by weight of polyethylene glycol, 2 parts by weight of chitosan, 1 part by weight of zinc acetylacetonate, and 1 part by weight of silane coupling agent, prepared by a casting process. It is denoted as film D4.

[0053] Comparative Example 5

[0054] A biodegradable film comprises: 60 parts by mass of lactic acid polymer (PLA), 30 parts by mass of a copolymer of butylene adipate and butylene terephthalate (PBAT), 1 part by mass of epoxidized soybean oil, 2 parts by mass of polycaprolactone diol, 1.5 parts by mass of talc, 1.5 parts by mass of polyethylene glycol, 1 part by mass of zinc acetylacetonate, 0.3 parts by mass of triphenylphosphine, and 1 part by mass of a silane coupling agent, prepared by a casting process. It is denoted as film D5.

[0055] Comparative Example 6

[0056] A biodegradable film comprises: 60 parts by weight of PLA, 30 parts by weight of PBAT, 1.5 parts by weight of talc, 1.5 parts by weight of polyethylene glycol, 2 parts by weight of chitosan, 1 part by weight of zinc acetylacetonate, 0.3 parts by weight of triphenylphosphine, and 1 part by weight of silane coupling agent, prepared by a casting process. It is denoted as film D6.

[0057] Comparative Example 7

[0058] A biodegradable film comprises: 60 parts by weight of PLA, 30 parts by weight of PBAT, 1 part by weight of epoxidized soybean oil, 2 parts by weight of polycaprolactone diol, 2 parts by weight of chitosan, 1 part by weight of zinc acetylacetonate, 0.3 parts by weight of triphenylphosphine, and 1 part by weight of silane coupling agent, prepared by a casting process. It is denoted as film D7.

[0059] The casting processes in Examples 1-7 and Comparative Examples 1-7 were prepared according to the following process: S1. Mix all kinds of granules required for production evenly according to the corresponding proportions, put them into the hopper of the granulator, form a molten state through the heating device, cool them, and then cut them under the action of the cutting blades through the transmission device. Collect the dried granules and exhaust them through the cyclone separator and bag filter, and number them 1-14, which correspond to the ingredients of Examples 1-7 and Comparative Examples 1-7 respectively.

[0060] S2. The newly produced mixed particles are poured into the hopper of the casting machine. Through the rotation of the single-screw extruder, the particles are gradually fed from the collector into the barrel. Different sections of the barrel are equipped with heating devices, so that the particles are gradually heated and melted during the conveying process, eventually forming a flowing melt.

[0061] S3. The melt then passes through the extruder filter screen to remove coking and impurities caused by overheating, and is extruded into thin sheets through a transverse "T" die.

[0062] S4. The sheet enters the casting roller device, where it is stretched, cooled, and shaped to form a film. The film is then wound into a roll by a traction and winding device, ultimately producing a biodegradable film.

[0063] By adjusting the extruder speed, the linear speed of the casting roller and traction roller, and the winding and edge-receiving parameters, film or sheet samples of different thicknesses can be prepared.

[0064] test

[0065] 1. Basic mechanical, optical and barrier properties

[0066] The test results are shown in Table 1. Tensile properties (tensile strength, elongation at break, and modulus of elasticity) were tested at room temperature according to GB / T1040.3-2006 "Determination of tensile properties of plastics - Part 3: Test conditions for films and sheets"; haze and transmittance were tested according to GB / T 2410-2008 "Determination of transmittance and haze of transparent plastics"; water vapor transmission was tested at 38℃ and 90% relative humidity according to GB / T 1037-2021 "Determination of water vapor transmission properties of plastic films and sheets - Cup method of weight gain and loss"; oxygen transmission was tested at 23℃ and 0% relative humidity according to GB / T 1038-2000 "Test method for gas permeability of plastic films and sheets - Pressure difference method".

[0067] Table 1. Test results of mechanical, optical and barrier properties

[0068] It can be seen that Examples 1-7 successfully prepared films possessing high toughness, dynamic self-healing properties, antibacterial properties, and biodegradability, while the overall performance of the films in Comparative Examples 1-7 showed a significant decline. Specifically, comparing Example 1 (dual-core catalysis) with Comparative Example 3 (single catalysis, similar composition), Example 1, while maintaining high strength (39.5 MPa), significantly increased elongation at break by 23% to 478%, and decreased elastic modulus. This indicates that the material formed a more optimized dynamic cross-linked network under the action of the dual-core catalytic system (zinc acetylacetonate / triphenylphosphine), achieving a balance between high strength and high toughness. Comparing Example 1 with Comparative Example 5 (no compatibilizer), the lack of compatibilizer (epoxidized soybean oil and polycaprolactone diol) led to a precipitous drop in mechanical properties (tensile strength decreased by 36%, elongation at break decreased by 61%) and a surge in haze, proving that compatibilizers are crucial for improving PLA / PBAT compatibility and ensuring mechanical properties and transparency. Comparing Example 1 with Comparative Example 6 (without nucleating agent), the lack of nucleating agents (talc and polyethylene glycol) leads to a decrease in material rigidity (reduced modulus) and a significant deterioration in barrier properties (water vapor permeability increases by 58%), demonstrating that nucleating agents play an irreplaceable role in improving crystal density, enhancing rigidity, and improving barrier properties. Comparative Example 7 (containing chitosan, dual-nuclear catalysis) maintains its high transparency (92% transmittance) while possessing excellent mechanical and barrier properties, indicating that the introduction of chitosan successfully integrates antibacterial function without compromising other core properties.

[0069] 2. Dynamic self-healing performance test: Under a humid environment (RH>90%, 25℃), the film was subjected to controlled scratches (depth ~10μm), and the repair process was observed. The results are shown in Table 2.

[0070] Table 2. Dynamic self-healing performance test results

[0071] As shown in Table 2, the damage repair speed (closure rate >90% after 2 hours) of Example 1 and Comparative Example 7, which employ a dual-core catalytic system, is nearly twice that of the single-catalytic systems (Comparative Examples 2 and 3), achieving highly efficient repair of microscopic damage and more thorough restoration of mechanical properties after repair (≥97%). This indicates that zinc acetylacetonate and triphenylphosphine in the formulation of this application produce a synergistic catalytic effect of "1+1>2", greatly accelerating the dynamic transesterification reaction and achieving rapid and efficient repair of microscopic damage. This provides a key technical path for solving the problems of easy damage and short lifespan of bio-based materials.

[0072] 3. Antibacterial performance test: Referring to GB / T 31402-2015 "Test Method for Antibacterial Properties of Plastic Surfaces", the antibacterial performance of the film was tested using the film lamination method. The results are shown in Table 3.

[0073] Table 3 Antibacterial performance test

[0074] As shown in Table 3, all samples with added chitosan (Examples 1-7, Comparative Example 4, and Comparative Example 7) exhibited inhibition rates of over 94% against the two common pathogenic bacteria, demonstrating that the formulation of this application imparts a potent and broad-spectrum antibacterial function to the film. The weak antibacterial activity of Comparative Example 3 (without chitosan) originated from the PLA / PBAT substrate itself. Comparing Comparative Example 4 (single catalysis) with Examples 1 / 7 (dual-nuclear catalysis), the latter showed comparable or even superior antibacterial rates, indicating that the dual-nuclear catalysis system and the antibacterial function of chitosan have good compatibility and synergy, without producing any negative impact.

[0075] 4. Degradation performance test: The composting conditions were in accordance with GB / T 19277.1-2025 "Determination of final aerobic biodegradability of materials under controlled composting conditions (using the method for determining the release of carbon dioxide, Part 1: General method)". The degradation behavior of the film was tested under standard composting conditions. The results are shown in Table 4.

[0076] Table 4 Degradation performance test results

[0077] As can be seen, Examples 1-7 all exhibit typical intelligent degradation curves: the weight loss rate remained at a low level (<13%) after 30 days, demonstrating good stability during the service life; while entering the rapid degradation stage within 60-90 days, the weight loss rate exceeded 82% after 60 days and exceeded 96% after 90 days. Data from Comparative Examples 3 and 1 also show that the nucleating agent can ensure the initial stability of the film. By increasing crystallinity, the nucleating agent significantly enhances the material's early-stage resistance to degradation. Data from Comparative Examples 3, 4, 7, and Example 1 show that the dual-nuclear catalysis and chitosan drive the rapid degradation in the later stages. It is speculated that chitosan, as a microbial nutrient source, initiates faster degradation, while the addition of the dual-nuclear catalysis system may promote the hydrolysis of polymer chains in a composting environment through its dynamic exchange characteristics. The synergistic effect of these two factors results in a shorter degradation half-life. It shortens the time by about 30%, and the disintegration speed is greatly increased in the later stage.

[0078] The above experiments demonstrate that the formulation provided in this application can prepare a dynamically self-healing, high-toughness bio-based biodegradable film, balancing the contradiction between the need for stability during the service life and the need for rapid degradation after disposal in existing bio-based biodegradable films. The film formulation provided in this application is well-suited for applications such as agricultural mulch films that have precise life-cycle requirements, providing an ideal material solution for addressing white pollution at its source.

[0079] The above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A dynamically self-healing, high-toughness, biodegradable film, characterized in that, include: 20-70 parts by weight of lactic acid polymer, 20-70 parts by weight of copolymer of butylene adipate and butylene terephthalate, 1-5 parts by weight of compatibilizer, 1-5 parts by weight of nucleating agent, 1-3 parts by weight of catalyst, 0.5-1.0 parts by weight of auxiliaries and 1-4 parts by weight of antibacterial agent; The catalyst is composed of a main catalyst and a co-catalyst mixed at a mass ratio of 1:(0.1~0.5). The main catalyst includes any one or more combinations of zinc acetylacetonate, iron acetylacetonate, antimony trioxide, and zinc oxide. The co-catalyst is selected from any one of triethylamine, triphenylphosphine, and aluminum acetylacetonate.

2. The dynamically self-healing, high-toughness, bio-based biodegradable film as described in claim 1, characterized in that, The main catalyst is zinc acetylacetone, and the co-catalyst is triethylamine or triphenylphosphine. The mass ratio of the main catalyst to the co-catalyst is 1: (0.1~0.5).

3. The dynamically self-healing, high-toughness bio-based biodegradable film as described in claim 1, characterized in that, The melt index of the lactic acid polymer is 3-5 g / 10 min, and the melt index of the copolymer of butylene adipate and butylene terephthalate is 3-5 g / 10 min.

4. The dynamically self-healing, high-toughness, bio-based biodegradable film as described in claim 1, characterized in that, The compatibilizer is an epoxide or a diol oligomer, wherein the epoxide is epoxidized soybean oil; the diol oligomer is a diol oligomer containing primary hydroxyl groups at both ends, with a number average molecular weight of 1000~10000, and is selected from polyether diols and / or polyester diols.

5. The dynamically self-healing, high-toughness, bio-based biodegradable film as described in claim 4, characterized in that, The polyether diol is selected from at least one of polyethylene glycol, polytetrahydrofuran, and block copolymers of polyethylene glycol and polytetrahydrofuran, and the polyester diol is selected from any one or a combination of several of the following: polybutanediol, polycaprolactone diol, polyhexanediol, polybutanediol, polysuccinic acid-octanediol, polydecanediol, polyoctanediol, polybutanediol, polyoctanediol, polydecanediol, and polyhexanediol.

6. The dynamically self-healing, high-toughness, bio-based biodegradable film as described in claim 1, characterized in that, The nucleating agent is talc or polyethylene glycol, the auxiliary agent is a silane coupling agent, and the antibacterial agent is chitosan.

7. The dynamically self-healing, high-toughness bio-based biodegradable film as described in claim 1, characterized in that, The thickness of the film is 20~50 μm.

8. A method for preparing a dynamic self-healing, high-toughness bio-based biodegradable film as described in any one of claims 1-7, characterized in that, Includes the following steps: S1. Weigh out the raw materials in each mass fraction, add them to the granulator, and after heating, melting, cooling, and cutting, obtain uniform mixed particles; S2. The mixed particles are dried at 80°C until the moisture content is below 200 ppm; S3. The dried mixed particles are added to the blown film equipment, and after extrusion by the casting machine, filtration, die forming, and cooling and shaping by the casting roller, the desired film is obtained.

9. The preparation method according to claim 8, characterized in that, The barrel temperature of the granulator is 160~210℃, and the stirring speed is 280~320 r / min.

10. The application of a dynamic self-healing, high-toughness bio-based biodegradable film as described in any one of claims 1-7 in the preparation of functional plastic products, wherein the functional plastic products include packaging materials and coatings.

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