Degradable antibacterial bio-based composite film material and preparation method thereof

Abstract

The application discloses a degradable antibacterial bio-based composite film material and a preparation method thereof, and relates to the technical field of degradable materials.The composite film material is prepared from PPCP, PBAT and PHBV as ternary substrates, modified bamboo powder, modified montmorillonite, bacterial cellulose and functional additives through drying and mixing, plasticizing and granulating, and film blowing forming.The application breaks through the bottleneck that the strength and toughness of traditional materials are difficult to be considered simultaneously through complementary performance of substrates and synergy of filler-substrate interface, and the material has high tensile strength, excellent elongation at break, and integrated antibacterial property, gas barrier property and biodegradability, and does not contain toxic and side components and has excellent biocompatibility.The preparation process of the application is simple and controllable, and the cost is low, and the application is suitable for large-scale production, can be widely applied to the fields of food packaging, medical dressings and the like, and has remarkable practical value.

Description

Technical Field

[0001] This invention relates to the field of biodegradable materials technology, and in particular to a biodegradable antibacterial bio-based composite film material and its preparation method. Background Technology

[0002] Currently, the global plastics industry relies heavily on fossil resources. Traditional plastic products are difficult to degrade naturally, leading to "white pollution" problems such as soil pollution and microplastic accumulation in water bodies after disposal. Furthermore, their production processes generate high carbon emissions, making the transformation of plastic materials towards green and biodegradable materials an urgent need for the industry. Against this backdrop, biodegradable bio-based materials, with their core advantages of being renewable and environmentally friendly, have become a key direction for replacing traditional plastics. Among them, polyhydroxybutyrate-valerate copolyester (PHBV), polybutylene adipate-terephthalate (PBAT), and phthalic anhydride-modified carbon dioxide copolymer (PPCP) have shown broad application potential in the field of film materials due to their unique performance characteristics. However, existing single-substrate or simple binary blend systems all have insurmountable performance shortcomings, limiting their large-scale application.

[0003] Polyhydroxybutyrate-valerate copolyester (PHBV) possesses excellent biocompatibility and complete biodegradability, along with high mechanical strength, giving it a natural advantage in applications with stringent safety requirements, such as food contact and medical materials. However, its inherent drawbacks are significant. On one hand, its slow crystallization rate leads to long processing cycles and low production efficiency; on the other hand, its high brittleness and insufficient elongation at break make the finished product prone to cracking during use, severely limiting its solo application. Polybutylene adipate terephthalate (PBAT) exhibits excellent ductility and film-forming properties, outstanding water resistance, and good processing fluidity, effectively improving the toughness of blended systems. However, its low crystallinity and weak mechanical strength make it prone to deformation when used alone, failing to meet the basic load-bearing and tensile strength requirements of packaging materials. Phthalic anhydride-modified carbon dioxide copolymer (PPCP) successfully overcomes the shortcomings of traditional carbon dioxide copolymer (PPC) in terms of poor thermal stability and weak barrier properties by introducing a rigid benzene ring structure. Moreover, the resource utilization of carbon dioxide in the raw material is in line with the concept of green chemistry, and the production cost is significantly lower than that of polylactic acid (PLA). However, the tensile strength and elongation at break of PPCP when molded alone are still difficult to meet the needs of practical applications, and it is impossible to balance the mechanical load-bearing capacity and service durability of the material.

[0004] In existing technologies, most solutions to address the aforementioned substrate defects focus on binary blend systems (such as PBAT / PHBV and PPCP / PLA), attempting to optimize the overall material performance through the complementary properties of the two substrates. However, limited by the performance boundaries of binary systems, a synergistic balance of "high strength, high toughness, heat resistance, and controllable degradation" cannot be achieved, often resulting in inherent contradictions such as "increased toughness leads to decreased strength" and "accelerated degradation leads to decreased heat resistance." More importantly, traditional binary blend systems lack integrated design of functional properties. As the requirements for material performance in fields such as food packaging and medical protective equipment continue to upgrade, relying solely on basic mechanical properties is no longer sufficient to meet high-level demands. For example, food packaging needs antibacterial properties to inhibit microbial growth and extend shelf life, while medical materials need precise barrier properties to prevent contamination and ensure safe use. Traditional blend systems struggle to simultaneously guarantee excellent overall performance. Although natural functional fillers possess antibacterial or barrier functions, their poor interfacial compatibility with the substrate leads to stress concentration and deterioration of mechanical properties, making it difficult to achieve the expected functional reinforcement effect. The basic mechanical properties of materials are difficult to integrate with functional properties such as antibacterial and barrier properties, which cannot meet the diverse needs of high value-added fields such as food packaging and medical protection.

[0005] Therefore, there is an urgent need to provide a composite film material that combines high strength and toughness, heat resistance and stability, controllable degradation, natural antibacterial properties and excellent barrier properties, so as to provide a practical technical solution for its large-scale application in food packaging, medical protection and other fields. Summary of the Invention

[0006] The purpose of this invention is to provide a biodegradable antibacterial bio-based composite film material and its preparation method, thereby solving the problems existing in the prior art. This composite film material possesses excellent mechanical properties, as well as superior antibacterial, biodegradable, and breathable / moisture-permeable properties. It has a wide range of applications, controllable costs, and can be mass-produced.

[0007] To achieve the above objectives, the present invention provides the following solution: One of the technical solutions of this invention is to provide a biodegradable antibacterial bio-based composite film material, wherein the raw materials include the following components by weight: 40-60 parts PPCP, 32-48 parts PBAT, 8-12 parts PHBV, 4-9 parts modified bamboo powder, 3-8 parts modified montmorillonite, 1-5 parts bacterial cellulose, 0.20-1.6 parts antioxidant, 2-4 parts compatibilizer and 0.5-1 part stabilizer; The modified bamboo powder is obtained by sequentially modifying bamboo powder through polydopamine coating and maleic anhydride grafting; wherein the bamboo powder is a product processed from common bamboo varieties such as moso bamboo, nan bamboo, and ci bamboo.

[0008] The modified montmorillonite is obtained by modifying montmorillonite with an organic modifier.

[0009] Furthermore, the preparation method of the modified bamboo powder includes the following steps: (1) In a buffer system with pH 8.0~9.0, bamboo powder and dopamine are mixed and reacted for 10~20 hours to form a polydopamine coating layer on the surface of bamboo powder, and polydopamine-coated bamboo powder is obtained. (2) In the presence of a silane coupling agent, the polydopamine-coated bamboo powder is reacted with maleic anhydride at 50-70°C for 2-4 hours to achieve covalent grafting of maleic anhydride onto the surface of the bamboo powder, thereby obtaining the modified bamboo powder.

[0010] Furthermore, the mass ratio of bamboo powder, dopamine, and maleic anhydride is 50:0.7~1.3:1.8~3.2.

[0011] Further, the silane coupling agent is one or both of γ-aminopropyltriethoxysilane and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane; the mass ratio between the bamboo powder and the silane coupling agent is 50:3.5~6.5; and the particle size of the modified bamboo powder is 80~120 mesh.

[0012] Furthermore, the organic modifier includes one or more of bis(octadecyldimethylammonium chloride) (DDAB), hexadecyltrimethylammonium bromide (CTAB), and octadecyltrimethylammonium chloride (OTAC); the mass ratio of montmorillonite to the organic modifier is 10:1.4~2.6.

[0013] Furthermore, the preparation method of the modified montmorillonite includes the following steps: Montmorillonite was dispersed in water to form a suspension, the organic modifier was added, and the mixture was reacted at 70-85°C. After separation, washing, and drying, the modified montmorillonite was obtained.

[0014] Furthermore, during the preparation of the modified montmorillonite, the reaction is carried out at 70~85℃ for 1~3 hours; the particle size of the modified montmorillonite is 50~150 μm.

[0015] Furthermore, the bacterial cellulose is obtained by vacuum freeze-drying at -10~-20℃ for 24 h and then pulverizing it; the preferred particle size is 50 μm.

[0016] Further, the antioxidant includes one or more of antioxidant 1010, antioxidant 1076, antioxidant 300, antioxidant 1790, antioxidant DSTBP, antioxidant 1098, antioxidant 168, and antioxidant 691.

[0017] Furthermore, the compatibilizer is one or more of acetylated tributyl citrate, ethylene-glycidyl methacrylate copolymer (EGMA), and γ-aminopropyltriethoxysilane.

[0018] Furthermore, the stabilizer includes one or more of maleic anhydride, epoxidized soybean oil, dimethyltin dithioacetate isooctyl ester, inorganic mineral powder, metal oxide, and metal soap.

[0019] This invention also provides a method for preparing the above-mentioned biodegradable antibacterial bio-based composite film material, comprising the following steps: The raw materials were weighed according to the specified weight ratio, and then granulated and blown into film to obtain the biodegradable antibacterial bio-based composite film material.

[0020] The preferred preparation method includes the following steps: (1) Select raw materials according to the weight ratio, dry PHBV, PBAT, PPCP, modified bamboo powder, bacterial cellulose, modified montmorillonite and functional additives (antioxidant, compatibilizer and stabilizer) at 50~60 ℃ for 3-5 h, add them to the mixer, stir and mix at room temperature for 30 min until uniform, and obtain the mixture; (2) Plasticizing and granulating using a co-rotating parallel twin-screw extruder. After confirming that the equipment hopper, feed port and die head are clean, start the machine, heat up to 175~180 ℃, add the mixture, gradually adjust the main screw speed to 30~50 r / min, open the feed port and die head, and after the extruded filament is cooled by cooling water, it is cut and granulated by a pelletizer. (3) Use a blown film casting machine to blow film, adjust the temperature of the feeding section to 120~130 ℃, the temperature of the melting section to 125~135 ℃, and the temperature of the homogenization section to 130~140 ℃. After heating to the set temperature, pour the granules into the hopper, set the screw speed to 15~25 rpm, adjust the traction speed and winding speed, and the speed ratio of the two is 1:1.17, blow film to obtain a biodegradable antibacterial bio-based composite film material.

[0021] This invention constructs a ternary substrate system of PPCP, PBAT, and PHBV in specific weight ratios, and combines the complementary functions of modified bamboo powder, modified montmorillonite, and bacterial cellulose, successfully overcoming the performance bottlenecks of single-material and binary blend systems. Specifically, the rigid benzene rings of PPCP and the montmorillonite nanosheets form a "dual-network" reinforcing structure, while the three-dimensional nanonetworks of bamboo powder fiber and bacterial cellulose achieve synergistic toughening. Ultimately, this results in a film possessing both high tensile strength and excellent elongation at break, effectively solving the industry pain point of traditional biodegradable materials struggling to balance strength and toughness.

[0022] Compared to existing single-function biodegradable films, this invention achieves an integrated design of antibacterial, barrier, and biodegradability. Modified bamboo powder possesses natural antibacterial components and a porous structure, endowing the material with reliable antibacterial function while providing suitable air and moisture permeability. The nanosheet structure of modified montmorillonite significantly optimizes the material's barrier performance against oxygen and water vapor, effectively reducing microbial growth and condensation buildup within the packaging. Furthermore, the synergistic effect of PHBV and bacterial cellulose accelerates the composting degradation of the material, achieving a high degree of unity between functional properties and environmental requirements, perfectly meeting the diverse needs of food packaging, medical consumables, and other fields.

[0023] This invention uses renewable bio-based materials such as PPCP, PHBV, and PBAT as its core, supplemented by widely available and inexpensive fillers such as bamboo powder and montmorillonite. This not only achieves the resource utilization of waste materials but also significantly reduces the production cost of the materials. The preparation process does not require complex equipment or high-energy-consuming processes. The process parameters for plasticizing, granulation, and blown film are clear and controllable, making it feasible for large-scale industrial production and in line with the concept of green and sustainable development.

[0024] Furthermore, the composite film material prepared by this invention is free of heavy metals and toxic additives, has excellent biocompatibility, and also possesses comprehensive properties such as high strength and toughness, breathability and moisture permeability, and controllable degradation. It can be widely used in food packaging, disposable products, medical dressings and other fields, effectively expanding the high-value-added application scenarios of bio-based biodegradable materials and providing strong support for the large-scale promotion of such materials.

[0025] The present invention discloses the following technical effects: This invention achieves a breakthrough in the synergistic performance of biodegradable film materials through the scientific compounding of ternary substrates and modified fillers. The optimized ratio of PPCP, PBAT, and PHBV, combined with the complementary functions of modified bamboo powder, modified montmorillonite, and bacterial cellulose, utilizes the rigid benzene rings of PPCP and the montmorillonite nanosheets to form a "dual-network" reinforcement structure. Furthermore, the three-dimensional network of bamboo powder fibers and bacterial cellulose synergistically strengthens the material, giving it both high tensile strength and excellent elongation at break. This overcomes the traditional challenge of achieving a balance between strength and toughness, while significantly improving oxygen and water vapor barrier properties.

[0026] This invention achieves an integrated design of antibacterial, barrier and biodegradable properties, with outstanding comprehensive performance. Moreover, the material does not contain heavy metals or toxic additives, and can meet the stringent requirements of many fields such as food packaging and medical dressings.

[0027] This invention uses renewable bio-based materials as the core, supplemented by low-cost fillers to reduce production costs. The preparation process does not require complex equipment, the parameters are clear and controllable, and it is suitable for large-scale production, effectively expanding the high-value-added application scenarios of bio-based biodegradable materials. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 The results are the antibacterial test results of the composite film materials prepared in Examples 1-5 and Comparative Examples 1-7 of this invention. Detailed Implementation

[0030] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0031] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0032] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0033] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0034] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0035] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.

[0036] The methods for testing the mechanical properties, barrier properties, and antibacterial properties of the biodegradable antibacterial bio-based composite film materials in the following embodiments and comparative examples of the present invention are as follows: (1) Mechanical properties Mechanical properties were determined using a GBH electronic tensile testing machine: the composite film was cut into 50 mm × 20 mm sample strips, the sample strips were aligned with two clamps with an initial distance of 25 mm, and pulled at a speed of 50 mm / min until they broke. This was repeated 3 times, and the test results were recorded.

[0037] (2) Barrier performance ① The oxygen transmission rate was determined according to GB / T 19789-2021 and ASTM D1434 standards. The oxygen transmission rate (OTR) of the film was measured by differential pressure method using a gas transmission rate meter. The film sample (d=110 mm) was tested for 24 h at 23 ℃ and 50% relative humidity. The average value was taken after 3 measurements.

[0038] ② The water vapor transmission rate (WVTR) of the membrane was determined according to GB 1037-88 and ASTM E96 / E96M standards. The WVTR was measured using a water vapor transmission rate meter via the gravimetric method. Distilled water was poured into a dry, clean permeation cup, and a pre-treated membrane sample (d=90 mm) was placed inside the test chamber to seal the cup. The test was conducted for 24 hours at 38 ℃ and 90% humidity. Three measurements were performed, and the average value was taken.

[0039] (3) Antibacterial properties The antibacterial experiment used the plate count method. The composite film was cut into 3cm × 3cm pieces, placed in the bacterial suspension, and incubated at 37℃ in a shaking incubator for 4 hours. The shaken solution was then diluted 10-fold. 1 mL of the diluted solution was mixed thoroughly with nutrient agar and poured into sterile petri dishes. The dishes were incubated at 37℃ for 24 hours, and the colony count was observed and counted.

[0040] (1) NC: Viable bacteria count in the blank control group; NS: Viable bacteria count in the sample group.

[0041] (4) Degradation performance The soil degradation experiment was conducted using the soil burial method. The composite membrane was cut into 3cm × 3cm strips and buried in the soil (each sample pit was approximately 10-15 cm deep). The mass loss rate was measured every week, with the burial experiment lasting five weeks. Before burial, the samples were placed in an oven at 60 °C for approximately 15 h to constant weight, and the mass M0 before degradation was recorded. Subsequently, the samples were dried in a 60 °C vacuum oven for 15 h to constant weight, and the mass Mt after degradation was recorded. The mass loss rate of the composite membrane at different degradation times was calculated using formula (2). The experiment was conducted three times, and the average value was taken.

[0042] (2) Example 1 This embodiment provides a biodegradable antibacterial bio-based composite thin film material, the preparation process of which is as follows: (1) Preparation of modified bamboo powder: a. Weigh 10g of bamboo powder and spread it evenly in a petri dish. Dry it in an oven at 100℃ for 24 hours and cool it to room temperature for later use. b. Measure 133 mL of pH 8.5, 50 mM Tris-HCl buffer, add 0.2 g of dopamine, and stir magnetically until completely dissolved to obtain a dopamine-modified solution; c. Transfer 10g of bamboo powder to the solution, stir and soak at 25 ℃ in the dark for 15 h, filter, wash with deionized water until neutral, and dry at 60 ℃ to obtain coated bamboo powder; d. Add 1 g of silane coupling agent KH550 to 45 mL of ethanol, stir magnetically until dissolved, add 5 mL of deionized water, and continue stirring for 30 min to hydrolyze the silane coupling agent to form a 1% KH550 ethanol aqueous solution. Then add 0.5 g of maleic anhydride, sonicate for 10 min, and add 0.1 mL of concentrated sulfuric acid to accelerate dissolution. Then transfer the coated bamboo powder to this solution, stir and soak at 60 ℃ for 2.5 h, filter, wash 3 times with ethanol, and dry at 80 ℃ to obtain 100 mesh modified bamboo powder.

[0043] (2) Preparation of modified montmorillonite: a. Disperse 10 g of montmorillonite in 500 mL of ultrapure water and magnetically stir for 1 h in a 70 ℃ water bath to prepare a uniform suspension; after standing for 10 min, discard the large particles of sediment at the bottom and take the upper suspension for later use; then add 2 g of trichloroacetic acid to the suspension and continue stirring for 30 min, and remove insoluble impurities by centrifugation to obtain suspension A1; b. Dissolve 2 g DDAB in 50 mL anhydrous ethanol, stir in a 60 ℃ water bath until completely dissolved, and prepare solution A2 with a concentration of 40 g / L; c. Place suspension A1 in an 80 ℃ water bath environment, and slowly add solution A2 dropwise at a stirring rate of 500 rpm. After the addition is complete, keep the solution at the temperature and stir for 2 h, and then let it cool naturally to room temperature. Then, centrifuge at 3000 rpm for 10 min, discard the supernatant, wash the precipitate three times with anhydrous ethanol, and then vacuum dry at 60 ℃ for 12 h. Crush the dried product and sieve it to obtain modified montmorillonite with a particle size of 150 μm.

[0044] (3) Pretreatment of bacterial cellulose: Bacterial cellulose was freeze-dried under vacuum at -10~-20 ℃ for 24 h, pulverized by an ultra-micro pulverizer and sieved to obtain bacterial cellulose with a diameter of 50 μm.

[0045] (4) Raw material mixing: The following raw materials are accurately weighed according to the following parts by weight: 40 parts phthalic anhydride modified carbon dioxide copolymer (PPCP), 32 parts polybutylene adipate-terephthalate (PBAT), 8 parts polyhydroxybutyrate-valerate copolyester (PHBV), 4 parts modified bamboo powder, 3 parts modified montmorillonite, 1 part bacterial cellulose, 1.2 parts antioxidant 1010, 4 parts tributyl acetylacetonate (compensator), and 1 part maleic anhydride (stabilizer). All the above raw materials are dried at 50°C for 5 hours to remove moisture, and then transferred to a mixer. The mixture is stirred and mixed at room temperature for 30 minutes to ensure that the components are evenly dispersed and a homogeneous mixture is obtained.

[0046] (5) Plasticizing and granulating: Plasticizing and granulating is carried out using a co-rotating parallel twin-screw extruder. First, check and confirm that the hopper, feed port, and die of the equipment are clean and free of impurities. Then, start the equipment and heat it to 175°C. After the temperature stabilizes, add the above mixture to the hopper, gradually adjust the speed of the main screw to 30 r / min, and open the feed port and die at the same time to allow the mixture to be fully plasticized and melted under the action of screw shearing and high temperature, and extruded to form continuous filaments. After the filaments are cooled by cooling water, they are cut into uniform particles by a pelletizer to obtain composite granules.

[0047] (6) Film blowing: Film is prepared using a blown film casting machine. Adjust the equipment temperature parameters: feeding section 120℃, melting section 125℃, homogenization section 130℃. After the temperature of each section reaches the set value and stabilizes, pour the above composite granules into the hopper, set the screw speed to 15 rpm, and adjust the traction speed and winding speed at the same time to control the speed ratio of the two to 1:1.17. Start the equipment to perform blown film operation, and finally obtain a biodegradable antibacterial bio-based composite film material.

[0048] Performance testing: The mechanical properties, barrier properties and antibacterial properties of the prepared composite film material were tested according to the test methods specified above in this invention. The test results are shown in Table 1 and Figure 1.

[0049] Example 2 This embodiment provides a biodegradable antibacterial bio-based composite thin film material, the preparation process of which is as follows: Steps (1)-(3) are the same as in Example 1.

[0050] (4) Raw material mixing: The following raw materials are accurately weighed according to the following weight parts: 45 parts phthalic anhydride modified carbon dioxide copolymer (PPCP), 36 parts polybutylene adipate terephthalate (PBAT), 9 parts polyhydroxybutyrate valerate copolyester (PHBV), 5 parts modified bamboo powder, 5 parts modified montmorillonite, 2 parts bacterial cellulose, 1.2 parts antioxidant 1076, 4 parts ethylene-glycidyl methacrylate copolymer (compatibilizer), and 1 part epoxidized soybean oil (stabilizer). All the above raw materials are dried at 50℃ for 4 hours to remove moisture, and then transferred to a mixer. The mixture is stirred and mixed at room temperature for 30 minutes to ensure that the components are evenly dispersed and a homogeneous mixture is obtained.

[0051] (5) Plasticizing and granulating: Plasticizing and granulating is carried out using a co-rotating parallel twin-screw extruder. First, check and confirm that the hopper, feed port, and die of the equipment are clean and free of impurities. Then, start the equipment and heat it to 180°C. After the temperature stabilizes, add the above mixture to the hopper, gradually adjust the speed of the main screw to 30 r / min, and open the feed port and die at the same time to allow the mixture to be fully plasticized and melted under the action of screw shearing and high temperature, and extruded to form continuous filaments. After the filaments are cooled by cooling water, they are cut into uniform particles by a pelletizer to obtain composite granules.

[0052] (6) Film blowing: Film is prepared using a blown film casting machine. Adjust the equipment temperature parameters: feeding section 125℃, melting section 130℃, homogenization section 135℃. After the temperature of each section reaches the set value and stabilizes, pour the above composite granules into the hopper, set the screw speed to 15 rpm, and adjust the traction speed and winding speed at the same time to control the speed ratio of the two to 1:1.17. Start the equipment to perform blown film operation, and finally obtain a biodegradable antibacterial bio-based composite film material.

[0053] Performance testing: The mechanical properties, barrier properties and antibacterial properties of the prepared composite film material were tested according to the test methods specified above in this invention. The test results are shown in Table 1 and Figure 1.

[0054] Example 3 This embodiment provides a biodegradable antibacterial bio-based composite thin film material, the preparation process of which is as follows: Steps (1)-(3) are the same as in Example 1.

[0055] (4) Raw material mixing: The following raw materials are accurately weighed according to the following parts by weight: 50 parts phthalic anhydride modified carbon dioxide copolymer (PPCP), 40 parts polybutylene adipate terephthalate (PBAT), 10 parts polyhydroxybutyrate valerate copolyester (PHBV), 6 parts modified bamboo powder, 6 parts modified montmorillonite, 3 parts bacterial cellulose, 1.2 parts antioxidant 1790, 4 parts γ-aminopropyltriethoxysilane (compensator), and 1 part dimethyltin dithioacetate isooctyl ester (stabilizer). All the above raw materials are dried at 60°C for 3 hours to remove moisture, and then transferred to a mixer. The mixture is stirred and mixed at room temperature for 30 minutes to ensure that the components are evenly dispersed and a homogeneous mixture is obtained.

[0056] (5) Plasticizing and granulating: Plasticizing and granulating is carried out using a co-rotating parallel twin-screw extruder. First, check and confirm that the hopper, feed port, and die of the equipment are clean and free of impurities. Then, start the equipment and heat it to 175°C. After the temperature stabilizes, add the above mixture to the hopper, gradually adjust the speed of the main screw to 40 r / min, and open the feed port and die at the same time to allow the mixture to be fully plasticized and melted under the action of screw shearing and high temperature, and extruded to form continuous filaments. After the filaments are cooled by cooling water, they are cut into uniform particles by a pelletizer to obtain composite granules.

[0057] (6) Film blowing: Film is prepared using a blown film casting machine. Adjust the equipment temperature parameters: feeding section 125℃, melting section 130℃, homogenization section 135℃. After the temperature of each section reaches the set value and stabilizes, pour the above composite granules into the hopper, set the screw speed to 20 rpm, and adjust the traction speed and winding speed at the same time to control the speed ratio of the two to 1:1.17. Start the equipment to perform blown film operation, and finally obtain a biodegradable antibacterial bio-based composite film material.

[0058] Performance testing: The mechanical properties, barrier properties and antibacterial properties of the prepared composite film material were tested according to the test methods specified above in this invention. The test results are shown in Table 1 and Figure 1.

[0059] Example 4 This embodiment provides a biodegradable antibacterial bio-based composite thin film material, the preparation process of which is as follows: Steps (1)-(3) are the same as in Example 1.

[0060] (4) Raw material mixing: The following raw materials are accurately weighed according to the following parts by weight: 55 parts phthalic anhydride modified carbon dioxide copolymer (PPCP), 44 parts polybutylene adipate terephthalate (PBAT), 11 parts polyhydroxybutyrate valerate copolyester (PHBV), 7 parts modified bamboo powder, 7 parts modified montmorillonite, 4 parts bacterial cellulose, 1.2 parts antioxidant 300, 4 parts tributyl acetylacetonate (compensator), and 1 part epoxidized soybean oil (stabilizer). All the above raw materials are dried at 50°C for 4 hours to remove moisture, and then transferred to a mixer. The mixture is stirred and mixed at room temperature for 30 minutes to ensure that the components are evenly dispersed and a homogeneous mixture is obtained.

[0061] (5) Plasticizing and granulating: Plasticizing and granulating is carried out using a co-rotating parallel twin-screw extruder. First, check and confirm that the hopper, feed port, and die of the equipment are clean and free of impurities. Then, start the equipment and heat it to 180°C. After the temperature stabilizes, add the above mixture to the hopper, gradually adjust the speed of the main screw to 45 r / min, and at the same time open the feed port and die to allow the mixture to be fully plasticized and melted under the action of screw shearing and high temperature, and extruded to form continuous filaments. After the filaments are cooled by cooling water, they are cut into uniform particles by a pelletizer to obtain composite granules.

[0062] (6) Film blowing: Film preparation is carried out using a blown film casting machine. Adjust the equipment temperature parameters: feeding section 120℃, melting section 125℃, homogenization section 135℃. After the temperature of each section reaches the set value and stabilizes, pour the above composite granules into the hopper, set the screw speed to 20 rpm, and adjust the traction speed and winding speed at the same time to control the speed ratio of the two to 1:1.17. Start the equipment to carry out the blown film operation, and finally obtain the biodegradable antibacterial bio-based composite film material.

[0063] Performance testing: The mechanical properties, barrier properties and antibacterial properties of the prepared composite film material were tested according to the test methods specified above in this invention. The test results are shown in Table 1 and Figure 1.

[0064] Example 5 This embodiment provides a biodegradable antibacterial bio-based composite thin film material, the preparation process of which is as follows: Steps (1)-(3) are the same as in Example 1.

[0065] (4) Raw material mixing: The following raw materials are accurately weighed according to the following parts by weight: 60 parts phthalic anhydride modified carbon dioxide copolymer (PPCP), 48 parts polybutylene adipate terephthalate (PBAT), 12 parts polyhydroxybutyrate valerate copolyester (PHBV), 9 parts modified bamboo powder, 8 parts modified montmorillonite, 1.2 parts bacterial cellulose, 0.4 parts antioxidant 168, 4 parts γ-aminopropyltriethoxysilane (compensator), and 1 part maleic anhydride (stabilizer). All the above raw materials are dried at 55℃ for 3 hours to remove moisture, and then transferred to a mixer. The mixture is stirred and mixed at room temperature for 30 minutes to ensure that the components are evenly dispersed and a homogeneous mixture is obtained.

[0066] (5) Plasticizing and granulating: Plasticizing and granulating is carried out using a co-rotating parallel twin-screw extruder. First, check and confirm that the hopper, feed port, and die of the equipment are clean and free of impurities. Then, start the equipment and heat it to 175°C. After the temperature stabilizes, add the above mixture to the hopper, gradually adjust the speed of the main screw to 50 r / min, and open the feed port and die at the same time to allow the mixture to be fully plasticized and melted under the action of screw shearing and high temperature, and extruded to form continuous filaments. After the filaments are cooled by cooling water, they are cut into uniform particles by a pelletizer to obtain composite granules.

[0067] (6) Film blowing: Film preparation is carried out using a blown film casting machine. Adjust the equipment temperature parameters: feeding section 125℃, melting section 135℃, homogenization section 140℃. After the temperature of each section reaches the set value and stabilizes, pour the above composite granules into the hopper, set the screw speed to 25 rpm, and adjust the traction speed and winding speed at the same time to control the speed ratio of the two to 1:1.17. Start the equipment to carry out the blown film operation, and finally obtain the biodegradable antibacterial bio-based composite film material.

[0068] Performance testing: The mechanical properties, barrier properties and antibacterial properties of the prepared composite film material were tested according to the test methods specified above in this invention. The test results are shown in Table 1 and Figure 1.

[0069] Comparative Example 1 The only difference from Example 3 is that no modified bamboo powder was added.

[0070] Performance testing: The mechanical properties, barrier properties and antibacterial properties of the prepared composite film material were tested according to the test methods specified above in this invention. The test results are shown in Table 1 and Figure 1.

[0071] Comparative Example 2 The only difference from Example 3 is that no modified montmorillonite was added.

[0072] Performance testing: The mechanical properties, barrier properties and antibacterial properties of the prepared composite film material were tested according to the test methods specified above in this invention. The test results are shown in Table 1 and Figure 1.

[0073] Comparative Example 3 The only difference from Example 3 is that no bacterial cellulose was added.

[0074] Performance testing: The mechanical properties, barrier properties and antibacterial properties of the prepared composite film material were tested according to the test methods specified above in this invention. The test results are shown in Table 1 and Figure 1.

[0075] Comparative Example 4 The only difference from Example 3 is that PHBV was not added, and the raw materials were accurately weighed by weight as follows: 56 parts phthalic anhydride modified carbon dioxide copolymer (PPCP), 44 parts polybutylene adipate terephthalate (PBAT), 6 parts modified bamboo powder, 6 parts modified montmorillonite, 3 parts bacterial cellulose, 1.2 parts antioxidant 1790, 4 parts γ-aminopropyltriethoxysilane (compensator), and 1 part dimethyltin dithioacetate isooctyl ester (stabilizer).

[0076] Performance testing: The mechanical properties, barrier properties and antibacterial properties of the prepared composite film material were tested according to the test methods specified above in this invention. The test results are shown in Table 1 and Figure 1.

[0077] Comparative Example 5 The only difference from Example 3 is that the ternary ratio is deviated, and the raw materials are accurately weighed by weight as follows: 70 parts phthalic anhydride modified carbon dioxide copolymer (PPCP), 20 parts polybutylene adipate terephthalate (PBAT), 10 parts polyhydroxybutyrate valerate copolyester (PHBV), 6 parts modified bamboo powder, 6 parts modified montmorillonite, 3 parts bacterial cellulose, 1.2 parts antioxidant 1790, 4 parts γ-aminopropyltriethoxysilane (compensator), and 1 part dimethyltin dithioacetate isooctyl ester (stabilizer).

[0078] Performance testing: The mechanical properties, barrier properties and antibacterial properties of the prepared composite film material were tested according to the test methods specified above in this invention. The test results are shown in Table 1 and Figure 1.

[0079] Comparative Example 6 The only difference from Example 3 is that PPCP is replaced with PLA, and the following raw materials are accurately weighed by weight: 50 parts polylactic acid (PLA), 40 parts polybutylene adipate terephthalate (PBAT), 10 parts polyhydroxybutyrate valerate copolyester (PHBV), 6 parts modified bamboo powder, 6 parts modified montmorillonite, 3 parts bacterial cellulose, 1.2 parts antioxidant 1790, 4 parts γ-aminopropyltriethoxysilane (compensator), and 1 part dimethyltin dithioacetate isooctyl ester (stabilizer).

[0080] Performance testing: The mechanical properties, barrier properties and antibacterial properties of the prepared composite film material were tested according to the test methods specified above in this invention. The test results are shown in Table 1 and Figure 1.

[0081] Comparative Example 7 The only difference from Example 3 is that the bamboo powder was not modified. The raw materials were accurately weighed by weight as follows: 50 parts phthalic anhydride modified carbon dioxide copolymer (PPCP), 40 parts polybutylene adipate terephthalate (PBAT), 10 parts polyhydroxybutyrate valerate copolyester (PHBV), 6 parts bamboo powder, 6 parts modified montmorillonite, 3 parts bacterial cellulose, 1.2 parts antioxidant 1790, 4 parts γ-aminopropyltriethoxysilane (compensator), and 1 part dimethyltin dithioacetate isooctyl ester (stabilizer).

[0082] Performance testing: The mechanical properties, barrier properties and antibacterial properties of the prepared composite film material were tested according to the test methods specified above in this invention. The test results are shown in Table 1 and Figure 1.

[0083] Table 1 As can be seen from the test results in Table 1, the biodegradable antibacterial bio-based composite film materials prepared in Examples 1-5 of this invention exhibit excellent comprehensive performance. Among them, Example 5 showed the best tensile strength (32 MPa), while its oxygen permeability (510 cm³ / (m²•24h•0.1 MPa)) and water vapor permeability (280 g / (m²•24h)) were both low, indicating particularly outstanding barrier performance. Example 3 had the highest mass loss rate (89%), indicating its optimal biodegradation efficiency. Comparative Example 4 lacked rigid PHBV, resulting in decreased strength and barrier performance. Comparative Example 5 had excessively high PPCP content, leading to excessively high hardness, brittleness, and reduced elongation at break. Comparative Example 7 used unmodified bamboo powder, resulting in poor interfacial compatibility, reduced elongation at break, and decreased barrier performance.

[0084] The composite film prepared by the multi-component synergistic compounding method and process of the present invention has significant advantages such as high tensile strength and low oxygen permeability and water vapor permeability. It has excellent water and gas barrier effects and can effectively play a good role in preservation and aroma preservation, which fully meets the needs of food packaging, medical protection and other fields.

[0085] The antibacterial test results of the biodegradable antibacterial bio-based composite film materials of Examples 1-5 and Comparative Examples 1-7 are shown in the figure. Figure 1 .

[0086] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A biodegradable antibacterial bio-based composite thin film material, characterized in that, The raw materials comprise the following components by weight: 40-60 parts PPCP, 32-48 parts PBAT, 8-12 parts PHBV, 4-9 parts modified bamboo powder, 3-8 parts modified montmorillonite, 1-5 parts bacterial cellulose, 0.2-1.6 parts antioxidant, 2-4 parts compatibilizer and 0.5-1 part stabilizer; The modified bamboo powder is obtained by sequentially modifying bamboo powder with polydopamine coating and maleic anhydride grafting. The modified montmorillonite is obtained by modifying montmorillonite with an organic modifier.

2. The biodegradable antibacterial bio-based composite film material according to claim 1, characterized in that, The preparation method of the modified bamboo powder includes the following steps: (1) In a buffer system with pH 8.0~9.0, bamboo powder and dopamine are mixed and reacted for 10~20h to form a polydopamine coating layer on the surface of bamboo powder, and polydopamine coated bamboo powder is obtained. (2) In the presence of a silane coupling agent, the polydopamine-coated bamboo powder is reacted with maleic anhydride at 50-70°C for 2-4 hours to achieve covalent grafting of maleic anhydride onto the surface of the bamboo powder, thereby obtaining the modified bamboo powder.

3. The biodegradable antibacterial bio-based composite film material according to claim 1, characterized in that, The silane coupling agent includes one or both of γ-aminopropyltriethoxysilane and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane.

4. The biodegradable antibacterial bio-based composite film material according to claim 1, characterized in that, The organic modifier includes one or more of bis(octadecyldimethylammonium chloride), hexadecyltrimethylammonium bromide, and octadecyltrimethylammonium chloride.

5. The biodegradable antibacterial bio-based composite film material according to claim 1, characterized in that, The preparation method of the modified montmorillonite includes the following steps: Montmorillonite was dispersed in water to form a suspension, the organic modifier was added, and the mixture was reacted at 70-85°C. After separation, washing, and drying, the modified montmorillonite was obtained.

6. The biodegradable antibacterial bio-based composite film material according to claim 1, characterized in that, The antioxidants include one or more of antioxidants 1010, 1076, 300, 1790, DSTBP, 1098, 168, and 691.

7. The biodegradable antibacterial bio-based composite film material according to claim 1, characterized in that, The compatibilizer is one or more of acetylated tributyl citrate, ethylene-glycidyl methacrylate copolymer, and γ-aminopropyltriethoxysilane.

8. The biodegradable antibacterial bio-based composite film material according to claim 1, characterized in that, The stabilizer includes one or more of maleic anhydride, epoxidized soybean oil, dimethyltin dithioacetate isooctyl ester, inorganic minerals, metal oxides, and metal soaps.

9. The method for preparing the biodegradable antibacterial bio-based composite thin film material according to any one of claims 1-8, characterized in that, Includes the following steps: The raw materials were weighed according to the specified weight ratio, and then granulated and blown into film to obtain the biodegradable antibacterial bio-based composite film material.

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