Antibacterial, antioxidant, anti-ultraviolet degradable food packaging film and preparation method and application thereof

Abstract

The application belongs to the field of new materials, and particularly relates to an antibacterial, antioxidant and ultraviolet-resistant degradable food packaging film and a preparation method and application thereof, and specifically to a degradable food packaging film prepared by melt blending, extrusion and blow molding of caffeic acid phenethyl ester, talcum powder and PBAT / PLA; through the synergistic effect of the rigidity enhancement of talcum powder and the antibacterial, antioxidant and ultraviolet-resistant functions of caffeic acid phenethyl ester, the film is endowed with long-acting antibacterial, high-efficiency ultraviolet-resistant performance and excellent 1,1-diphenyl-2-trinitrobenzene hydrazine free radical scavenging capacity. The packaging film can be completely biodegraded, can effectively delay the corruption and deterioration of perishable foods such as fruits and vegetables, prolong the shelf life, the film preparation process is simple, safe, suitable for industrial production, environment-friendly and has a wide application prospect.

Description

Technical Field

[0001] This invention belongs to the field of biodegradable food packaging materials, specifically relating to an antibacterial, antioxidant, and UV-resistant biodegradable food packaging film, its preparation method, and its application. Background Technology

[0002] Plastic cling film, as an important packaging material for food preservation, is widely used in households, supermarkets, and the catering industry. Traditional cling film is mainly made of plastics such as polyethylene (PE) and polyvinyl chloride (PVC). Although it has good film-forming properties, transparency, and barrier properties, it is non-renewable, difficult to degrade, and easily causes environmental problems. With the increasing global awareness of environmental protection, the development of environmentally friendly and biodegradable cling film has become an inevitable trend in the industry.

[0003] Polybutylene adipate / terephthalate (PBAT) and polylactic acid (PLA) are currently the most promising biodegradable polymer materials for industrialization. PBAT, copolymerized from adipic acid, terephthalic acid, and 1,4-butanediol, possesses good flexibility, film-forming properties, and biodegradability, and can be completely degraded into carbon dioxide and water within 3-6 months under composting conditions. PLA, polymerized from polylactic acid monomers, has high tensile strength, and its raw materials are derived from renewable resources such as corn and sugarcane, exhibiting good biocompatibility and compostability. However, single PBAT / PLA blends still have many shortcomings in practical applications, limiting their promotion in the high-end food preservation field. On the one hand, PLA itself is brittle and has poor toughness, while PBAT lacks rigidity and has low mechanical strength. Simple blending of the two makes it difficult to balance the strength and toughness of the film, and the dimensional stability is poor, making it difficult to meet packaging requirements. On the other hand, both PBAT and PLA contain ester bonds in their molecular chain structure, which are prone to molecular chain breakage and oxidative degradation under ultraviolet radiation, heat, oxygen, and environmental factors. This leads to rapid film aging, a sharp decline in mechanical properties, and a significantly shortened service life. Furthermore, ordinary biodegradable films lack active antibacterial, antioxidant, and barrier functions. Small molecules such as oxygen and water vapor can easily permeate the film, accelerating food oxidation and spoilage, promoting microbial growth, and failing to block ultraviolet radiation from damaging food nutrients, pigments, and flavor compounds, resulting in limited preservation effects.

[0004] To address the aforementioned issues, existing technologies have made various attempts at improvement. Chinese patent CN118440373A discloses a PVA / phenethyl caffeate composite film, which utilizes the polyphenolic structure of phenethyl caffeate to endow the composite film with certain antibacterial and antioxidant properties, providing a useful approach for the development of functional packaging films. However, this technology still has significant limitations: the film material based on water-soluble PVA has poor water resistance and insufficient mechanical strength, and it does not incorporate talc-like layered inorganic barrier fillers to construct a physical barrier, thus failing to effectively improve the film's water vapor and gas barrier properties; furthermore, its full-band UV protection effect has not been clearly verified. Chinese patent CN115011083A adds talc as a reinforcing agent to the PBAT / PLA matrix, effectively improving the mechanical properties of the composite material, but it lacks antibacterial design and its UV protection function is unclear, making it difficult to meet the long-term antibacterial and stable preservation requirements of food packaging. While Chinese patent CN121517778A utilizes tea polyphenols / anthocyanins for dual antioxidant effects, its antibacterial component content is low (0.02-0.16 parts), lacks broad-spectrum antibacterial verification, anthocyanins exhibit poor photothermal stability and are prone to degradation, the starch substrate has insufficient water resistance and glycerol is easily migrated, and its UV protection function is unclear, making it difficult to meet the requirements for long-lasting antibacterial properties, stable preservation, and safety in food packaging. Existing patent CN110894346A achieves high UV barrier protection and recyclability, but lacks antibacterial design, has no active antioxidant mechanism, and only delays oxidation through physical barrier. Furthermore, its multi-layered composite structure is non-degradable and difficult to separate and recycle, failing to meet the requirements for active food preservation and environmental protection throughout its entire life cycle. Chinese patent CN121379063A discloses a PBAT / PLA antibacterial film with added composite antibacterial agent and modified structural starch. The nano-silver-nano-titanium dioxide composite antibacterial agent modified with silane coupling agent improves the dispersibility of the antibacterial agent in the matrix and achieves a broad-spectrum and long-lasting antibacterial effect. However, the composite antibacterial agent is expensive, and nano-silver is prone to discoloration when exposed to light and preheating, posing a risk of migration into food.

[0005] Existing technologies often employ inorganic fillers or functional additives to modify the PBAT / PLA system. Talc, as an inorganic filler, is beneficial for improving the mechanical strength and rigidity of the film and has a certain shielding effect against ultraviolet rays, making it a commonly used green filler in biodegradable materials. However, relying solely on talc modification, the film still suffers from insufficient UV resistance, lack of antioxidant and antibacterial functions, and cannot meet the multifunctional requirements of food preservation.

[0006] Phenylacetyl caffeate is a natural phenolic compound with excellent UV absorption, free radical scavenging, antioxidant, and antibacterial activities. It is also safe, non-toxic, and biodegradable, making it highly compatible with food packaging requirements. However, current research on the application of phenylacetyl caffeate in biodegradable films is limited, especially lacking a systematic approach to combining it with talc to achieve synergistic enhancement of multiple functions, including mechanical reinforcement, gas barrier properties, antibacterial activity, antioxidant properties, and UV protection.

[0007] Therefore, developing a biodegradable food packaging film that combines antibacterial, antioxidant, and UV-resistant properties can solve the problems of existing products having limited functionality, short shelf life, and poor environmental adaptability, while also meeting the needs of industrial production and conforming to the trend of green and sustainable development. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of existing PBAT / PLA composite films, such as insufficient mechanical properties, limited functionality, and limited barrier properties, and to provide a biodegradable food packaging film with antibacterial, antioxidant, and UV-resistant properties, as well as its preparation method and applications. This invention prepares a biodegradable food packaging film by melt blending and extrusion blow molding of phenylethyl caffeate (CAPE), talc, and PBAT / PLA. Through the synergistic effect of the rigidity-enhancing properties of talc and the antibacterial, antioxidant, and UV-resistant functions of phenylethyl caffeate, the film is endowed with long-lasting antibacterial, highly effective UV-resistant properties, and excellent antioxidant capacity, while ensuring the biodegradability and industrial production feasibility of the film, providing an efficient and environmentally friendly packaging solution for the preservation of perishable foods.

[0009] To achieve the above objectives, the specific technical solution of the present invention is as follows: A biodegradable food packaging film with antibacterial, antioxidant, and UV-resistant properties, comprising the following raw material components by weight: 90-98 parts of fully biodegradable resin (PBAT / PLA), 5 parts of talc, and 1-5 parts of phenethyl caffeate. Furthermore, the fully bio-based degradable resin is a mixture of PBAT and PLA, with a mass ratio of PBAT to PLA of 90-95:5-10, preferably 90:5, at which point the membrane achieves the best balance between flexibility and strength. Furthermore, the particle size of the fully biodegradable resin is 2-4 mm.

[0010] Furthermore, the purity of the caffeic acid phenethyl ester is ≥98%.

[0011] Furthermore, the talc powder is food-grade talc powder with a particle size of 2000-5000 mesh, whiteness ≥90%, silica content ≥60%, and magnesium oxide content ≥30%; preferably, the talc powder has a particle size of 3000 mesh.

[0012] Furthermore, the final biodegradable food packaging film has a thickness of 30-40μm. If the thickness is too thin, the barrier and mechanical properties will be insufficient, while if it is too thick, the cost will increase and it will not be conducive to degradation. 30-40μm can balance the requirements of performance and cost.

[0013] The core innovation of this invention lies in organically combining the physical modification advantages of talc with the chemical functional advantages of phenethyl caffeate, and applying them in combination to the PBAT / PLA biodegradable system to achieve a synergistic modification effect of physical enhancement and chemical function. Talc focuses on improving the mechanical properties and gas barrier properties of the film, and provides physical-level UV shielding; phenethyl caffeate focuses on achieving antibacterial, antioxidant, and chemical-level UV absorption. The two complement each other's weaknesses and synergistically enhance each other, solving the problem that talc modification alone lacks antibacterial and antioxidant functions and has limited UV protection, while also compensating for the inability of phenethyl caffeate alone to improve the mechanical and barrier properties of the film. This successfully overcomes the technical bottleneck of existing modification technologies that cannot simultaneously achieve multiple performance improvements.

[0014] This invention further provides a method for preparing the above-mentioned antibacterial, antioxidant, and UV-resistant biodegradable food packaging film, comprising the following steps: Step 1: Vacuum dry the fully biodegradable resin particles, phenylethyl caffeate, and talc powder at 75-85 ℃ for 15-20 h, with a vacuum degree of -0.08 to -0.1 MPa, to remove moisture from the materials and avoid affecting the processing performance and membrane quality. Step 2: Add the dried material obtained in Step 1 into a high-speed mixer according to the formula, and mix at a speed of 2000-3000 rpm for 6-10 minutes to ensure that all components are fully mixed. Step 3: Add the mixed material to a twin-screw extruder, set the feed rate to 80-180 g / min and the screw speed to 30-40 rpm. Control the five temperature zones of the extruder from the feed inlet to the die head to be 160-170 ℃, 165-175 ℃, 170-180 ℃, 165-175 ℃, and 160-170 ℃ respectively. After the material is melt-blended, it is extruded from the die head, air-dried, and then granulated by a pelletizer to obtain composite masterbatch. Step 4: Vacuum dry the composite masterbatch at 75-85 ℃ for 15-20 h, then feed it into a single-screw extruder. Set the screw speed to 30-50 rpm. Control the four temperature zones of the extruder from the feed inlet to the die head to 155-165 ℃, 160-170 ℃, 165-175 ℃, and 160-170 ℃ respectively. After the material is melted and extruded, it is fed into a blown film machine to form a blown film. During the blown film process, the traction rate is 20-40 Hz, the fan speed is 40-60 Hz, and the take-up rate is 10-20 Hz to complete the film preparation. After the film is cooled and shaped, it is wound up and stored in a dry, cool place away from light.

[0015] The antibacterial, antioxidant, and UV-resistant biodegradable food packaging film provided by this invention can be widely used for the preservation of perishable foods such as fruits, vegetables, and edible fungi.

[0016] Compared with the prior art, the present invention achieves the following beneficial effects: This invention achieves multifunctional synergistic optimization by combining phenethyl caffeate and talc, resulting in improved performance. Tensile strength and elongation at break are both more than 20% higher than existing PBAT / PLA films, meeting the requirements for stretching, folding, and transportation in food packaging. Furthermore, it exhibits strong antioxidant capabilities, high DPPH free radical scavenging rate, and UV shielding, effectively delaying lipid oxidation in food.

[0017] This invention employs an extrusion blow molding process, requiring no special equipment and is compatible with existing plastic film production equipment. The synthesis process is simple, and the entire production process generates no waste, meeting the industry's requirements for green production and enabling large-scale industrial production. The food packaging film prepared by this invention is suitable for the preservation packaging of various perishable foods such as fruits and vegetables, and can also be used for protective packaging in food transportation and warehousing, possessing broad market application prospects and industrialization value. Attached Figure Description

[0018] Figure 1 The graph shows the mechanical properties of the food packaging film in Experiment Example 1. Figure 2 This is a graph showing the antibacterial properties of the food packaging film in Experiment Example 2; Figure 3 This is a graph showing the antioxidant properties of the food packaging film in Experiment Example 3; Figure 4 This is a graph showing the UV resistance results of the food packaging film in Experiment Example 4; Figure 5 These are photos of the preservation effect of bananas preserved with food packaging film in Experiment Example 5, stored at 25 ℃ for different times. Detailed Implementation

[0019] The technical solution of the present invention will be further described below with reference to specific embodiments. These embodiments are only used to illustrate the technical solution of the present invention in more detail and should not be construed as limiting the scope of protection of the present invention.

[0020] Unless otherwise specified, all reagents used in the following examples are commercially available.

[0021] Example 1: A biodegradable food packaging film containing phenethyl caffeate, possessing antibacterial, antioxidant, and UV-resistant properties, and its preparation method, the specific steps of which are as follows: (1) PBAT, PLA, talc, and phenethyl caffeate were vacuum dried at 80°C for 15 h with a vacuum degree of -0.1 MPa; (2) Add the dried PBAT, PLA, talc and phenethyl caffeate to a high-speed mixer in a weight ratio of 90:5:5:1 and mix at 3000 rpm for 10 min. (3) The above mixture is fed into a twin-screw extruder, the feed rate is set to 80-180 g / min and the screw speed is 35 rpm. The temperatures of the five temperature zones from the feed inlet to the die head of the extruder are set to 165 ℃, 170 ℃, 175 ℃, 170 ℃ and 165 ℃ respectively. After the material is melt-blended, it is extruded from the die head, air-dried and then sent to a pelletizer for granulation to obtain composite masterbatch. (4) The composite masterbatch was vacuum dried at 80℃ for 15 hours, and then fed into a single-screw extruder. The screw speed was set to 40 rpm, and the temperatures of the four temperature zones from the feed inlet to the die head of the extruder were set to 160 ℃, 165 ℃, 170 ℃, and 165 ℃ respectively. After melt extrusion, the material was fed into a blown film machine for blow molding. During the blow molding process, the traction rate was adjusted to 20 Hz, the fan speed to 50 Hz, and the take-up rate to 20 Hz to complete the film preparation. The obtained film was sealed in a black opaque plastic bag and stored in a dry, cool, and dark place. The thickness of the packaging film was controlled between 32±1 μm.

[0022] Example 2: A biodegradable food packaging film containing phenethyl caffeate, possessing antibacterial, antioxidant, and UV-resistant properties, and its preparation method, the specific steps of which are as follows: (1) PBAT, PLA, talc, and phenethyl caffeate were vacuum dried at 80°C for 15 h with a vacuum degree of -0.1 MPa; (2) Add the dried PBAT, PLA, talc, and phenethyl caffeate to a high-speed mixer in a weight ratio of 90:5:5:2 and mix at 3000 rpm for 10 min. (3) The above mixture is fed into a twin-screw extruder, the feed rate is set to 80-180 g / min and the screw speed is 35 rpm. The temperatures of the five temperature zones from the feed inlet to the die head of the extruder are set to 165 ℃, 170 ℃, 175 ℃, 170 ℃ and 165 ℃ respectively. After the material is melt-blended, it is extruded from the die head, air-dried and then sent to a pelletizer for granulation to obtain composite masterbatch. (4) The composite masterbatch was vacuum dried at 80℃ for 15 hours, and then fed into a single-screw extruder. The screw speed was set to 40 rpm, and the temperatures of the four temperature zones from the feed inlet to the die head of the extruder were set to 160 ℃, 165 ℃, 170 ℃, and 165 ℃ respectively. After melt extrusion, the material was fed into a blown film machine for blow molding. During the blow molding process, the traction rate was adjusted to 20 Hz, the fan speed to 50 Hz, and the take-up rate to 20 Hz to complete the film preparation. The obtained film was sealed in a black opaque plastic bag and stored in a dry, cool, and dark place. The thickness of the packaging film was controlled between 32±1 μm.

[0023] Example 3: A biodegradable food packaging film containing phenethyl caffeate, possessing antibacterial, antioxidant, and UV-resistant properties, and its preparation method, the specific steps of which are as follows: (1) PBAT, PLA, talc and phenethyl caffeate were vacuum dried at 75°C for 20 h with a vacuum degree of -0.1 MPa.

[0024] (2) Add the dried PBAT, PLA, talc and phenethyl caffeic acid to a high-speed mixer in a weight ratio of 90:5:5:3 and mix at 3000 rpm for 10 min.

[0025] (3) The above mixture is fed into a twin-screw extruder, the feed rate is set to 80-180 g / min and the screw speed is 35 rpm. The temperatures of the five temperature zones from the feed inlet to the die head of the extruder are set to 165 ℃, 170 ℃, 175 ℃, 170 ℃ and 165 ℃ respectively. After the material is melt-blended, it is extruded from the die head, air-dried and then sent to a pelletizer for granulation to obtain composite masterbatch.

[0026] (4) The composite masterbatch was vacuum dried at 75℃ for 20h, and then fed into a single-screw extruder. The screw speed was set to 40 rpm, and the temperatures of the four temperature zones from the feed inlet to the die head of the extruder were set to 160℃, 165℃, 170℃, and 165℃ respectively. After melt extrusion, the material was fed into a blown film machine for blow molding. During the blow molding process, the traction rate was adjusted to 20 Hz, the fan speed to 50 Hz, and the take-up rate to 20 Hz to complete the film preparation. The obtained film was sealed in a black opaque plastic bag and stored in a dry, cool, and dark place. The thickness of the packaging film was controlled between 32±1 μm.

[0027] Example 4: A biodegradable food packaging film containing phenethyl caffeate, possessing antibacterial, antioxidant, and UV-resistant properties, and its preparation method, the specific steps of which are as follows: (1) PBAT, PLA, talc and phenethyl caffeate were vacuum dried at 80°C for 15 h with a vacuum degree of -0.1 MPa.

[0028] (2) Add the dried PBAT, PLA, talc and phenethyl caffeic acid to a high-speed mixer in a weight ratio of 90:5:5:5 and mix at 3000 rpm for 10 min.

[0029] (3) The above mixture is fed into a twin-screw extruder, the feed rate is set to 80-180 g / min and the screw speed is 35 rpm. The temperatures of the five temperature zones from the feed inlet to the die head of the extruder are set to 165 ℃, 170 ℃, 175 ℃, 170 ℃ and 165 ℃ respectively. After the material is melt-blended, it is extruded from the die head, air-dried and then sent to a pelletizer for granulation to obtain composite masterbatch.

[0030] (4) The composite masterbatch was vacuum dried at 80℃ for 15 hours, and then fed into a single-screw extruder. The screw speed was set to 40 rpm, and the temperatures of the four temperature zones from the feed inlet to the die head of the extruder were set to 160 ℃, 165 ℃, 170 ℃, and 165 ℃ respectively. After melt extrusion, the material was fed into a blown film machine for blow molding. During the blow molding process, the traction rate was adjusted to 20 Hz, the fan speed to 50 Hz, and the take-up rate to 20 Hz to complete the film preparation. The obtained film was sealed in a black opaque plastic bag and stored in a dry, cool, and dark place. The thickness of the packaging film was controlled between 32±1 μm.

[0031] Comparative Example 1: No added caffeic acid phenethyl ester and talc. The packaging film was prepared using the same steps as in Example 1, except that no phenethyl caffeate or talc was added in Comparative Example 1, while the other steps were the same as in Example 1.

[0032] Comparative Example 2: No addition of phenethyl caffeate The same steps as in Example 1 were used to package the film, except that talc was added as a barrier component in Comparative Example 2. PBAT, PLA and talc were mixed in a mass ratio of 90:5:5 and then added to the feed end of a twin-screw extruder. The remaining preparation steps were the same as in Example 1.

[0033] Experimental Example 1: Mechanical Property Testing The mechanical properties of the packaging films prepared in Examples 1-4 and Comparative Examples 1-2 were tested according to the test method of national standard GB 13022-91. The test results are shown in the figure. Figure 1 ; The results showed that, compared with Comparative Example 1, Examples 1-4 and Comparative Example 2 all improved the mechanical properties of the plastic wrap, indicating that talc powder is a rigid inorganic filler that improves the toughness of the film.

[0034] Experiment Example 2: Antibacterial Performance Test The antibacterial properties of the packaging films prepared in Examples 1-4 and Comparative Examples 1-2 were tested according to the national standard GB / T 31402-2023. Commonly available Escherichia coli and Staphylococcus aureus strains were used as test strains, and the cultures were incubated at 37 °C for 24 h. The bacterial solutions were then diluted to a concentration of 1×10⁻⁶. 6 CFU / mL bacterial suspension. 50 mg of the film samples from Examples 1-4 and Comparative Examples 1-2 were taken respectively and mixed with 1 mL of the above diluted bacterial suspension and co-cultured at 37℃ for 4 h. Then, 100 μL of the mixture was added dropwise to an agar plate (AGAR), spread evenly with a sterile spreader, and incubated at 37℃ for 12 h after inverting the plate. Colony growth was recorded and the antibacterial rate was calculated. The test results are shown below. Figure 2.

[0035] The results showed that, compared with Comparative Examples 1 and 2, Examples 1-4 had antibacterial properties, with Examples 3 and 4 exhibiting superior antibacterial ability compared to the others. This indicates that the addition of phenethyl caffeate can significantly improve the antibacterial properties of the film and show better antibacterial effects.

[0036] Experiment Example 3: Antioxidant Performance Test The antioxidant properties of the food packaging films prepared in Examples 1-4 and Comparative Examples 1-2 were tested.

[0037] Dissolve 1,1-diphenyl-2-trinitrophenylhydrazine (DPPH) in 24 mL of anhydrous ethanol, sonicate for 5 min, shake thoroughly, and store in the dark. Use within 5 h. Take 1 mL of the DPPH solution, dilute with 20 mL of anhydrous ethanol, measure its absorbance at 517 nm, and adjust the absorbance to 0.7 ± 0.05.

[0038] Weigh 25 mg of the film sample and add 5 mL of two different food simulation solutions, namely 10% ethanol solution and 50% ethanol solution, respectively. Soak the samples in the dark for 2 h to obtain the soaking solution.

[0039] Take 5 mL of the above soaking solution and mix it thoroughly with 30 mL of DPPH solution. React in the dark for 1 h to form the experimental group. Use the same volume of food simulant solution and anhydrous ethanol as the blank group, and use the same volume of deionized water and DPPH solution as the control group.

[0040] The absorbance of the supernatant in each group was measured at a wavelength of 517 nm. The DPPH radical scavenging rate was calculated based on the absorbance changes to evaluate the antioxidant performance of the film. The results are shown in [Figure number missing]. Figure 3 The results showed that, compared with Comparative Examples 1 and 2, Examples 1-4 all exhibited excellent DPPH free radical scavenging ability. Among them, Examples 2, 3, and 4 achieved scavenging rates of over 90% in a 50% ethanol simulated solution. This indicates that phenethyl caffeate, as a phenolic antioxidant, can efficiently capture free radicals, and when combined with talc, it can be stably loaded in the matrix and released in a controlled manner, significantly improving the antioxidant activity of the film and providing long-lasting antioxidant protection for biodegradable food packaging films.

[0041] Experiment Example 4: UV Resistance Test The UV resistance of the food packaging films prepared in Examples 1-4 and Comparative Examples 1-2 was tested. A UV-Vis spectrophotometer was used, with a scanning range of 200–800 nm, a scanning speed of 240 nm / min, and a slit width of 2 nm. The films were flattened and fixed in a sample holder, and the transmittance of the films to different wavelengths of light was measured using air as a reference. The results are shown in [Figure number missing]. Figure 4 .

[0042] The results showed that, compared with Comparative Examples 1 and 2, Examples 1-4 all exhibited superior UV protection performance. The synergistic effect of talc and phenethyl caffeate significantly improved the UV blocking performance of the film. Talc constructs a basic barrier through physical scattering and shielding, while phenethyl caffeate efficiently absorbs UV radiation in the UVA / UVB bands through its phenolic hydroxyl structure; the two work synergistically to achieve dual protection. As the phenethyl caffeate content increased, the UV transmittance of the film continuously decreased, with the sample in Example 4 exhibiting the best UV blocking effect, providing long-lasting UV protection for biodegradable food packaging films.

[0043] Experiment Example 5: Banana Preservation Test The packaging films prepared in Examples 1-4 and Comparative Examples 1-2 were used for banana preservation tests. Bananas of uniform ripeness were selected and wrapped with the packaging films of Comparative Examples 1-2 and Examples 1-4, respectively, and placed in an environment of 25 ℃ and 60% RH for 5 days for preservation testing. The appearance was observed and photographed for recording. The results are shown in […]. Figure 5 .

[0044] The results showed that bananas wrapped in Comparative Examples 1-2 and Example 1 exhibited oxidation and browning on their surface after 3 days, while Examples 2-4 extended the shelf life to varying degrees. With increasing shelf life, Examples 2-4 demonstrated an effect of extending the shelf life of bananas. Therefore, the biodegradable food packaging film provided by this invention possesses antibacterial, antioxidant, and UV-resistant functions, and has significant practical application value.

[0045] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any equivalent substitutions or modifications made by those skilled in the art within the spirit and principle of the present invention without any creative effort should be included within the protection scope of the present invention.

Claims

1. An antibacterial, antioxidant, and UV-degradable food packaging film, characterized in that, The raw materials include the following components by weight: 90-95 parts of PBAT / PLA blended resin, 5 parts of talc, and 1-5 parts of phenethyl caffeate; in the PBAT / PLA blended resin, the mass ratio of PBAT to PLA is 90-95:5-10.

2. The antibacterial, antioxidant, and UV-degradable food packaging film according to claim 1, characterized in that, The mass ratio of PBAT to PLA is 90:

5.

3. The antibacterial, antioxidant, and UV-degradable food packaging film according to claim 1 or 2, characterized in that, The particle size of the fully biodegradable resin is 2-4 mm.

4. The antibacterial, antioxidant, and UV-degradable food packaging film according to claim 1 or 2, characterized in that, The talc powder is food-grade talc powder with a particle size of 2000-5000 mesh, whiteness ≥90%, silica content ≥60%, and magnesium oxide content ≥30%.

5. The antibacterial, antioxidant, and UV-degradable food packaging film according to claim 4, characterized in that, The talc powder has a particle size of 3000 mesh.

6. The antibacterial, antioxidant, and UV-degradable food packaging film according to claim 4, characterized in that, The thickness of biodegradable food packaging film is 30-40μm.

7. The method for preparing the antibacterial, antioxidant, and UV-degradable food packaging film according to claim 1, characterized in that, Includes the following steps: Step 1: Vacuum dry the fully biodegradable resin particles, phenethyl caffeate, and talc powder at 75-85 ℃ for 15-20 h, with a vacuum degree of -0.08 to -0.1 MPa, to remove moisture from the materials; Step 2: Add the dried material obtained in Step 1 into a high-speed mixer according to the formula, and mix at a speed of 2000-3000 rpm for 6-10 minutes to ensure that all components are fully mixed. Step 3: Add the mixed material to a twin-screw extruder, set the feed rate to 80-180 g / min and the screw speed to 30-40 rpm. Control the five temperature zones of the extruder from the feed inlet to the die head to be 160-170 ℃, 165-175 ℃, 170-180 ℃, 165-175 ℃, and 160-170 ℃ respectively. After the material is melt-blended, it is extruded from the die head, air-dried, and then granulated by a pelletizer to obtain composite masterbatch. Step 4: Vacuum dry the composite masterbatch at 75-85 ℃ for 15-20 h, then feed it into a single-screw extruder. Set the screw speed to 30-50 rpm. Control the four temperature zones of the extruder from the feed inlet to the die head to 155-165 ℃, 160-170 ℃, 165-175 ℃, and 160-170 ℃ respectively. After the material is melted and extruded, it is fed into a blown film machine to form a blown film. During the blown film process, the traction rate is 20-40 Hz, the fan speed is 40-60 Hz, and the take-up rate is 10-20 Hz to complete the film preparation. After the film is cooled and shaped, it is wound up and stored in a dry, cool place away from light.

8. The application of the antibacterial, antioxidant, and UV-degradable food packaging film according to claim 1, characterized in that, The food packaging film is used for the preservation packaging of perishable foods, which are fruits, vegetables, or edible fungi.

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