Antibacterial degradable meal box material and preparation method thereof

Abstract

The invention discloses an antibacterial degradable meal box material and a preparation method thereof, and belongs to the field of degradable materials. The antibacterial degradable meal box material comprises the following raw materials in parts by mass: 25-40 parts of polylactic acid, 30-60 parts of high amylose, 10-15 parts of modified bamboo powder fibers, 1-3 parts of a plasticizer, 0.5-2 parts of an antioxidant and 0.5-2 parts of a lubricant, and polydopamine-epoxy silane is compounded on the modified bamboo powder fibers. Wherein the linear structure of the high amylose can help molecular chains to be better oriented and arranged, improve the tightness of molecular arrangement and help to improve the heat resistance and mechanical strength of the material. The bamboo powder fiber as a reinforcing phase can improve the impact resistance and tensile strength of the composite material, and after modification, the bamboo powder fiber can be used as a bridge of a matrix material, so that the compatibility and binding force between the bamboo powder fiber and the matrix and between the matrixes are improved, and the mechanical strength of the degradable material is improved.

Description

Technical Field

[0001] The present invention relates to the field of degradable materials, and in particular to an antibacterial degradable lunch box material and a preparation method thereof. Background Art

[0002] Plastic lunch boxes are widely used worldwide due to their low price, waterproofness, and oil resistance. However, they are difficult to decompose, significantly polluting the ozone layer and posing a serious threat to Earth's surface ecosystems. This threat is also increasingly impacting the living environment of humans and marine life. With growing environmental awareness, replacing traditional plastic tableware with biodegradable lunch boxes has become a key solution to addressing this "white pollution" problem.

[0003] At present, substitutes for plastic lunch boxes are mainly made of degradable plastics, that is, by adding certain photosensitizers to the plastic, the plastic product can be decomposed into low-molecular-weight compounds. However, these low-molecular-weight compounds cannot continue to decompose and will accumulate for a long time when flowing into the natural environment, causing harm to the environment. The other is degradable bioplastic products, which are mainly made of degradable materials such as straw. After use, they can be decomposed by microorganisms in the natural environment to produce non-toxic carbon dioxide and water, which meets the requirements of sustainable development.

[0004] Biodegradable materials are primarily composed of starch-based materials and plant fiber composites, but these materials have poor mechanical strength and thermal stability, making them prone to deformation when used to hold high-temperature food. Polylactic acid, a biodegradable plastic, was initially added as an additive to biodegradable lunch box materials. However, the inherent toughness of polylactic acid makes the resulting tableware brittle and its heat resistance poorly improved.

[0005] At the same time, since tableware materials are easily exposed to and breed bacteria during storage and transportation, it will seriously affect the safety of the tableware. General antibacterial agents contain metal ions such as silver ions, or are added with inorganic particles, which can easily migrate to the surface of the lunch box, and the safety of the tableware cannot be guaranteed.

[0006] Therefore, there is an urgent need to obtain a tableware material with high mechanical strength, antibacterial properties and good stability, which can simultaneously solve the dual problems of white pollution and food safety. Summary of the Invention

[0007] The present invention provides an antibacterial and degradable lunch box material and a preparation method thereof, which can solve the problems of poor mechanical strength and weak antibacterial function of degradable tableware materials in the prior art.

[0008] In a first aspect, the present invention provides an antibacterial and degradable lunch box material, comprising the following raw materials in parts by weight: 25-40 parts of polylactic acid; High amylose starch 30-60 parts; Modified bamboo fiber 10-15 parts; Plasticizer 1-3 parts; Antioxidant 0.5-2 parts; Lubricant 0.5-2 parts; The modified bamboo fiber is compounded with polydopamine-epoxy silane.

[0009] Preferably, the plasticizer includes a combination of one or more of tributyl citrate, trioctyl citrate and acetyl tributyl citrate.

[0010] Preferably, the antioxidant includes a combination of one or more of antioxidant 1010, antioxidant 1076, antioxidant 168, antioxidant 622, antioxidant 215, antioxidant B215, antioxidant B561 and antioxidant T502.

[0011] Preferably, the lubricant includes a combination of one or more of liquid paraffin, solid paraffin, microcrystalline paraffin, polyethylene wax and polytetrafluoroethylene wax.

[0012] By adopting the above technical scheme, the application selects polylactic acid and high amylose starch as the main matrix material, so that the degradable performance of the meal box material can be realized, and the application uses high amylose starch to replace conventional starch, and compared with ordinary starch, the high amylose starch has a long linear part, and the linear structure can help the molecular chain to be better oriented and arranged, improve the compactness of the molecular arrangement, enhance the hydrogen bond interaction between the molecules, and help to improve the heat resistance and mechanical strength of the material.

[0013] However, polylactic acid itself has high brittleness and low impact resistance, and after being compounded with high amylose starch, the strength of the degradable material can be improved to a certain extent, but since polylactic acid is a hydrophobic polyester and high amylose starch is a hydrophilic polyhydroxy compound, the difference in polarity between the two leads to poor compatibility and low interfacial bonding force in the compounding process, which affects the mechanical properties of the obtained degradable material.

[0014] In order to solve the above problems, the antibacterial degradable meal box material of the application further adds modified bamboo fiber, the filling of the bamboo fiber itself can improve the impact resistance and tensile strength of the composite material as a reinforcing phase, and will not affect the degradable performance of the degradable material. However, similarly, the surface of the bamboo fiber is also rich in hydrophilic hydroxyl groups, and when it is compounded with polylactic acid, there is still a problem of weak interfacial bonding, which leads to insignificant reinforcing effect. Therefore, the bamboo fiber is modified in the application, and the modified bamboo fiber is compounded with polydopamine-epoxy silane.

[0015] Polydopamine can connect with high-amylose starch through hydrogen bonding, and the epoxy groups in epoxy silane can form covalent bonds with the carboxyl groups in polylactic acid. On the one hand, it can improve the dispersibility and binding force of the bamboo powder fiber itself in the matrix material. On the other hand, it can act as a bonding bridge between polylactic acid and high-amylose starch, thereby improving the compatibility and interfacial bonding force between the matrix materials.

[0016] Moreover, through the double cross-linking effect of polydopamine-epoxy silane, the molecular arrangement density inside the degradable material can be further improved, connecting the bamboo powder fiber and the matrix material, so that the external force can be more effectively transmitted to the rigid bamboo powder fiber, inhibiting the brittle fracture of the matrix material, thereby improving the mechanical strength of the degradable material.

[0017] Polydopamine itself also has certain antibacterial properties. Polydopamine has excellent photothermal conversion capabilities, which can convert light energy into heat energy, denaturing the bacterial cell membrane and internal proteins, causing damage to the bacterial cell membrane and leakage of internal substances, leading to bacterial death; the polar groups contained in polydopamine can also destroy the cell membrane of microorganisms and interfere with the activity of metabolic enzymes in bacteria, thereby achieving broad-spectrum antibacterial effects.

[0018] Bamboo powder fiber itself contains natural antimicrobial ingredients that inhibit mold and bacteria. By compounding modified bamboo powder fiber into a matrix material, an antimicrobial and biodegradable lunch box material with high mechanical strength and antimicrobial properties can be obtained. Furthermore, because no metal antimicrobial agents or inorganic particles are introduced, the possibility of harmful components migrating to the lunch box surface is reduced, thereby improving the safety of the lunch box material.

[0019] Preferably, the raw materials of the modified bamboo powder fiber include bamboo powder fiber, dopamine hydrochloride and epoxy silane coupling agent in a mass ratio of 1: (0.1-0.15): (0.05-0.1).

[0020] Preferably, the particle size of the bamboo powder fiber is 40 to 60 meshes.

[0021] Preferably, the epoxy silane coupling agent includes one or more of 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane and 3-(2,3-glycidoxypropyl)methyldiethoxysilane.

[0022] Preferably, the modified bamboo powder fiber is prepared according to the following method: The bamboo powder fiber is dispersed in water, tris(hydroxymethylaminomethane) is added to adjust the pH value of the solution to 8-8.5, dopamine hydrochloride is added, and the mixture is stirred at room temperature for 24-48 hours, and finally washed, filtered and dried to obtain the pretreated fiber; The epoxy silane coupling agent is added to the alcohol solvent aqueous solution, the pH value of the solution is adjusted to 3-4.5, and the solution is stirred for reaction for 3-4 hours, and then the pretreated fiber is added and the stirring reaction is continued for 2-3 hours. Finally, the modified bamboo powder fiber is obtained by filtration, washing and drying.

[0023] Preferably, the alcohol solvent aqueous solution includes any one of a methanol aqueous solution and an ethanol aqueous solution with a mass fraction of 80 to 90%.

[0024] By adopting the above technical solution, dopamine hydrochloride is oxidized and self-polymerized in an alkaline environment, deposited in situ outside the bamboo powder fiber, and attached to the surface of the bamboo powder fiber. Then, the hydrolyzed epoxy silane coupling agent is mixed with the bamboo powder fiber composited with polydopamine. The hydrolyzed epoxy silane coupling agent contains silanol groups. Under the reaction conditions, the silanol groups will preferentially react with the hydroxyl groups in the polydopamine and the hydroxyl groups on the surface of the bamboo powder fiber to form covalent bonds, retaining the activity of the epoxy groups, and obtaining the bamboo powder fiber composited with polydopamine-epoxy silane.

[0025] Because the modified bamboo powder fiber is composited with polydopamine-epoxy silane on the surface, the steric hindrance formed can improve the dispersibility of bamboo powder fiber in the matrix material and reduce the agglomeration of bamboo powder fiber. Moreover, the epoxy groups in epoxy silane and the strong adhesion of polydopamine can simultaneously connect polylactic acid and high-amylose starch, which can not only improve the interfacial bonding force between bamboo powder fiber and the matrix material, but also improve the compatibility between polylactic acid and high-amylose starch, and enhance the interfacial effect between the components, thereby facilitating the transfer of stress and improving the mechanical strength and thermal stability of the degradable material.

[0026] The synergy between polydopamine and bamboo powder fiber can also give biodegradable materials antibacterial properties. Moreover, due to the strong bonding force between the modified bamboo powder fiber and the matrix material, the antibacterial ingredients are not easy to migrate to the surface of the lunch box material, resulting in the loss of antibacterial properties.

[0027] Preferably, the high-amylose starch is also compounded with tea polyphenols.

[0028] Preferably, the mass ratio of high-amylose starch to tea polyphenols is 1:(0.2-0.4).

[0029] Preferably, high-amylose starch is compounded with tea polyphenols according to the following method: The high-amylose starch is dissolved in water to prepare a suspension with a concentration of 2-4%, and then tea polyphenols are added. After stirring and reacting at 25-35°C for 1-2 hours, the suspension is centrifuged and freeze-dried to obtain the product.

[0030] By adopting the above technical solution, the phenolic hydroxyl groups in tea polyphenols can form a strong hydrogen bond network with the hydroxyl groups in high-amylose starch. Tea polyphenols can be adsorbed on high-amylose starch, which can enhance the binding force between tea polyphenols and modified bamboo powder fibers, improve the interfacial bridging effect, and introduce rigid benzene ring groups, which can further improve the mechanical strength of the degradable material.

[0031] Moreover, tea polyphenols can destroy the integrity of microbial cell membranes, and the phenolic hydroxyl groups they contain can be oxidized to produce active free radicals, thereby inhibiting the growth of microorganisms.

[0032] The catechol groups contained in the polydopamine in the modified bamboo powder fiber serve as reaction sites, synergistically reacting with tea polyphenols to further enhance the antimicrobial properties of the biodegradable material, achieving a long-lasting antimicrobial effect. Furthermore, because the antimicrobial components are complexed with the base material, there is no risk of antimicrobial migration, loss of antimicrobial properties, or compromising the safety of the lunch box material.

[0033] In a second aspect, the present invention provides a method for preparing an antibacterial and degradable lunch box material, comprising the following process steps: S1. Drying the polylactic acid; S2. Weigh the raw materials in corresponding parts by mass and stir to obtain a mixture; S3. The mixture is melt-extruded and granulated to obtain an antibacterial and biodegradable lunch box material.

[0034] Beneficial effects of the present invention: 1. The antibacterial and degradable lunch box material of the present invention uses polylactic acid and high-amylose starch as the base materials. The linear structure of high-amylose starch can help the molecular chains to better orient and arrange, improve the compactness of the molecular arrangement, enhance the hydrogen bonding effect between molecules, and help improve the heat resistance and mechanical strength of the material.

[0035] 2. The antibacterial and biodegradable lunch box material of the present invention also contains modified bamboo fiber. As a reinforcing phase, the bamboo fiber improves the composite's impact resistance and tensile strength without affecting the biodegradability of the biodegradable material. After modification, the fiber is combined with polydopamine-epoxysilane, which acts as a bridge to the matrix material, enhancing the compatibility and bonding between the bamboo fiber and the matrix, and between the matrix itself, and thus improving the mechanical strength of the biodegradable material.

[0036] 3. In the antibacterial and degradable lunch box material of the present invention, the high-amylose starch can also be compounded with tea polyphenols. Tea polyphenols can synergistically modify the polydopamine in the bamboo powder fiber to further improve the antibacterial properties of the degradable material and achieve long-term antibacterial effect. In addition, no metal antibacterial agents and inorganic particles are introduced, which also reduces the possibility of harmful components migrating to the surface of the lunch box, thereby improving the safety of the lunch box material. DETAILED DESCRIPTION

[0037] The specific embodiments of the present application are described in detail below, but it should be understood that the scope of the present application is not limited by the specific embodiments.

[0038] Preparation Example 1

[0039] Preparation Example 1-1, a modified bamboo powder fiber, was prepared according to the following method: 10 g of bamboo powder fiber (particle size of 40-60 mesh) was dispersed in 800 mL of water, and the pH value of the solution was adjusted to 8.5 by adding trimethylol aminomethane. 1.5 g of dopamine hydrochloride was added, and the reaction was stirred at room temperature for 48 h. Finally, the pretreated fiber was obtained by washing, suction filtration, and drying. 1 g of 3-glycidyloxypropyltrimethoxysilane was added to 50 mL of an 80% mass fraction ethanol aqueous solution, and the pH value of the solution was adjusted to 4. After stirring for 3 h, the pretreated fiber obtained above was added, and the reaction was continued to stir for 3 h. Finally, the modified bamboo powder fiber was obtained by washing, suction filtration, and drying.

[0040] Preparation Example 1-2, a modified bamboo powder fiber, was prepared according to the following method:

[0041] Preparation Example 1-3, a modified bamboo powder fiber, was prepared according to the following method:

[0042] Preparation Example 1-4, a modified bamboo powder fiber, was prepared according to the following method:

[0043] Preparation Example 1-5, a modified bamboo powder fiber, was prepared according to the following method: 1 g of 3-glycidyloxypropyltrimethoxysilane was added to 50 mL of an 80% mass fraction ethanol aqueous solution, and the pH value of the solution was adjusted to 4. After stirring for 3 h, the pretreated fiber obtained above was added, and the reaction was continued to stir for 3 h. Finally, the modified bamboo powder fiber was obtained by washing, suction filtration, and drying.

[0044] Preparation Example 1-6, a modified bamboo powder fiber, was prepared according to the following method: 10 g of bamboo powder fiber (particle size of 40-60 mesh) was dispersed in 800 mL of water, and the pH value of the solution was adjusted to 8.5 by adding trimethylol aminomethane. 1.5 g of dopamine hydrochloride was added, and the reaction was stirred at room temperature for 48 h. Finally, the pretreated fiber was obtained by washing, suction filtration, and drying.

[0045] Preparation Example 2

[0046] Preparation Example 2-1: A high-amylose starch was prepared according to the following method: Dissolve 10g of high-amylose starch in water to prepare a suspension with a concentration of 3%, then add 3g of tea polyphenols, stir and react at 30°C for 1h, then centrifuge and freeze-dry to obtain the product.

[0047] Example

[0048] Example 1, an antibacterial and degradable lunch box material, prepared according to the following method: S1. Polylactic acid (average molecular weight 3.0×10 4 ) for drying; S2 weighed 30 parts of polylactic acid after drying, 45 parts of high-amylose starch, 12 parts of the modified bamboo fiber prepared in Preparation Example 1-1, 2 parts of tributyl citrate, 1 part of antioxidant 1010 and 1 part of liquid paraffin, and stirred to obtain a mixture; S3. The mixture is melt-extruded and granulated to obtain an antibacterial and biodegradable lunch box material, wherein the melt-extrusion temperature is 160 to 210°C.

[0049] Example 2 and Example 3 are antibacterial and degradable lunch box materials. The only difference from Example 1 is that the raw material ratios are adjusted, as shown in Table 1: Table 1 Formula table of Examples 1 to 3

[0050] Wherein, Examples 2 and 3 both used the modified bamboo powder fiber prepared in Preparation Example 1-1.

[0051] Example 4, an antibacterial and degradable lunch box material, is different from Example 1 only in that the modified bamboo powder fiber prepared in Preparation Example 1-1 is replaced by an equal amount of the modified bamboo powder fiber prepared in Preparation Example 1-2.

[0052] Example 5, an antibacterial and degradable lunch box material, is different from Example 1 only in that the modified bamboo powder fiber prepared in Preparation Example 1-1 is replaced by an equal amount of the modified bamboo powder fiber prepared in Preparation Example 1-3.

[0053] Example 6, an antibacterial and degradable lunch box material, is different from Example 1 only in that the modified bamboo powder fiber prepared in Preparation Example 1-1 is replaced by an equal amount of the modified bamboo powder fiber prepared in Preparation Example 1-4.

[0054] Example 7, an antibacterial and degradable lunch box material, is different from Example 1 only in that the high-amylose starch prepared in Preparation Example 2-1 is used in place of the high-amylose starch.

[0055] Comparative Example

[0056] Comparative Example 1, an antibacterial and degradable lunch box material, is different from Example 1 only in that the modified bamboo powder fiber prepared in Preparation Example 1-1 is replaced by an equal amount of the modified bamboo powder fiber prepared in Preparation Example 1-5.

[0057] Comparative Example 2, an antibacterial and degradable lunch box material, is different from Example 1 only in that the modified bamboo powder fiber prepared in Preparation Example 1-1 is replaced by an equal amount of the modified bamboo powder fiber prepared in Preparation Example 1-6.

[0058] Comparative Example 3, an antibacterial and degradable lunch box material, is different from Example 1 only in that an equal amount of unmodified bamboo powder fiber is used to replace the modified bamboo powder fiber prepared in Preparation Example 1-1.

[0059] Example 4, an antibacterial and degradable lunch box material, differs from Example 1 only in that corn starch is used instead of high-amylose starch.

[0060] Performance testing

[0061] 1. Mechanical properties test: According to the relevant records in GB / T 1040.1-2025 "Determination of tensile properties of plastics Part 1: General principles", the tensile strength of the antibacterial and degradable lunch box materials obtained in the examples and comparative examples was tested. The test results are shown in Table 2.

[0062] 2. Antibacterial performance test: According to the relevant records in GB / T 31402-2023 "Determination of antibacterial activity on the surface of plastic boxes and other non-porous materials", the inhibition rates of the antibacterial and degradable lunch box materials obtained in the examples and comparative examples against Escherichia coli and Staphylococcus aureus after 24 hours were tested. The test results are shown in Table 3.

[0063] Table 2 Mechanical properties test results

[0064] Table 3 Antibacterial performance test results

[0065] According to Table 2 and Table 3, combined with Example 1 and Example 6, it can be seen that the antibacterial performance and mechanical strength of Example 6 are both lower than those of Example 1. The reason is that, during the preparation process of the modified bamboo powder fiber, an excessive amount of dopamine hydrochloride is added. When the formed polydopamine is excessively loaded on the surface of the bamboo powder fiber, the hydrophilic groups in the polydopamine are exposed, resulting in an increase in the polarity of the bamboo powder fiber surface, which in turn leads to a decrease in the bonding force between the bamboo powder fiber and the matrix material.

[0066] Combining Example 1 and Example 7, it can be seen that the antibacterial performance and mechanical strength of Example 7 are increased compared with Example 1. The reason is that the high-amylose starch used in Example 7 is also compounded with tea polyphenols. Tea polyphenols can cooperate with the polydopamine in the modified bamboo powder fiber to further promote the antibacterial performance of the degradable lunch box material. Moreover, the introduction of tea polyphenols can increase the binding force between the high-amylose starch and the modified bamboo powder fiber, thereby improving the stress transfer efficiency and enhancing the mechanical strength of the material.

[0067] Combining Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 3, it can be seen that the antibacterial properties and mechanical strength of Comparative Examples 1, 2, and 3 are all reduced compared to Example 1. This is because the modified bamboo powder fiber in Comparative Example 1 is not compounded with polydopamine. On the one hand, this reduces the number of epoxy silane grafting sites on the bamboo powder fiber. On the other hand, the lack of polydopamine's antibacterial properties and the bamboo powder fiber's inherent antibacterial properties significantly reduce its antibacterial properties. In Comparative Example 2, the modified bamboo powder fiber is not compounded with epoxy silane, resulting in a decrease in compatibility between the modified bamboo powder fiber and polylactic acid. In particular, there is no way to bridge the polylactic acid and high-amylose starch, resulting in a decrease in compatibility between the matrix materials, which in turn causes a decrease in mechanical strength. The bamboo powder fiber in Comparative Example 3, which was not modified, has a more significant performance decline.

[0068] Combining Example 1 and Comparative Example 4, it can be seen that the mechanical strength of Comparative Example 4 is lower than that of Example 1. The reason is that ordinary starch is used in Comparative Example 4 to replace the high-amylose starch in Example 1. Compared with ordinary starch, high-amylose starch can be better oriented, improve the compactness of molecular arrangement, and enhance the hydrogen bonding effect between molecules, thereby improving the mechanical strength of the degradable material.

[0069] The above disclosures are only a few specific embodiments of the present invention. However, the embodiments of the present invention are not limited thereto. Any changes that can be conceived by those skilled in the art should fall within the scope of protection of the present invention.

Claims

1. An antibacterial and degradable lunch box material, characterized in that: Including the following raw materials in parts by weight: 25-40 parts of polylactic acid; 30-60 parts of high amylose starch; 10-15 parts of modified bamboo powder fiber; 1 to 3 parts of plasticizer; 0.5-2 parts of antioxidant; 0.5-2 parts of lubricant; The modified bamboo powder fiber is compounded with polydopamine-epoxysilane.

2. The antibacterial and degradable lunch box material according to claim 1, characterized in that: The raw materials of the modified bamboo powder fiber include bamboo powder fiber, dopamine hydrochloride and epoxy silane coupling agent in a mass ratio of 1: (0.1-0.15): (0.05-0.1).

3. The antibacterial and degradable lunch box material according to claim 2, characterized in that: The particle size of the bamboo powder fiber is 40 to 60 meshes.

4. The antibacterial and degradable lunch box material according to claim 2, characterized in that: The epoxy silane coupling agent includes one or more of 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane and 3-(2,3-glycidoxypropyl)methyldiethoxysilane.

5. The antibacterial and degradable lunch box material according to claim 2, characterized in that: The modified bamboo powder fiber is prepared according to the following method: The bamboo powder fiber is dispersed in water, tris(hydroxymethylaminomethane) is added to adjust the pH value of the solution to 8-8.5, dopamine hydrochloride is added, and the mixture is stirred at room temperature for 24-48 hours, and finally washed, filtered and dried to obtain the pretreated fiber; The epoxy silane coupling agent is added to the alcohol solvent aqueous solution, the pH value of the solution is adjusted to 3-4.5, and the solution is stirred for reaction for 3-4 hours, and then the pretreated fiber is added and the stirring reaction is continued for 2-3 hours. Finally, the modified bamboo powder fiber is obtained by filtration, washing and drying.

6. The antibacterial and degradable lunch box material according to claim 1, characterized in that: The high-amylose starch is also compounded with tea polyphenols.

7. The antibacterial and degradable lunch box material according to claim 6, characterized in that: The mass ratio of the high-amylose starch to tea polyphenols is 1:(0.2-0.4).

8. The antibacterial and degradable lunch box material according to claim 6, characterized in that: The high-amylose starch is compounded with tea polyphenols according to the following method: The high-amylose starch is dissolved in water to prepare a suspension with a concentration of 2-4%, and then tea polyphenols are added. After stirring and reacting at 25-35°C for 1-2 hours, the suspension is centrifuged and freeze-dried to obtain the product.

9. The antibacterial and degradable lunch box material according to claim 1, characterized in that: The plasticizer includes a combination of one or more of tributyl citrate, trioctyl citrate and acetyl tributyl citrate.

10. A method for preparing an antibacterial and degradable lunch box material according to any one of claims 1 to 9, characterized in that: The process steps include: S1. Drying the polylactic acid; S2. Weigh the raw materials in corresponding parts by mass and stir to obtain a mixture; S3. The mixture is melt-extruded and granulated to obtain an antibacterial and biodegradable lunch box material.

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