Degradable high-strength plastic bag and preparation method thereof

Abstract

The invention discloses a degradable high-strength plastic bag and a preparation method thereof, and relates to the technical field of plastic bag preparation. The degradable high-strength plastic bag at least comprises the following raw materials in parts by mass: 40-60 parts of polylactic acid, 20-35 parts of poly (adipic acid) / butylene terephthalate, 5-15 parts of modified nano calcium carbonate, 3-8 parts of modified wood fibers, 6-8 parts of chitosan grafted polyglycidyl methacrylate nanoparticles, 0.5-2 parts of a lubricant, 0.3-1 part of an antioxidant and 2-5 parts of a degradation accelerator. And 0.5 to 1.5 parts of an ultraviolet stabilizer. According to the degradable high-strength plastic bag prepared by the preparation method disclosed by the invention, the polylactic acid and the poly (butylene adipate-co-terephthalate) are used as base materials, the modified nano calcium carbonate and the modified fibers are used as fillers, and the chitosan grafted polyglycidyl methacrylate nanoparticles are used as a compatilizer, so that the balance of high strength and degradability is realized; the prepared degradable high-strength plastic bag can be used as a high-performance flexible packaging material.

Description

Technical Field

[0001] This invention relates to the field of plastic bag manufacturing technology, specifically to a biodegradable high-strength plastic bag and its manufacturing method. Background Technology

[0002] Plastic bags, made primarily of plastic, are widely used to carry other items due to their low cost, light weight, large capacity, and ease of storage, making them an indispensable part of daily life. However, with increasing public concern about environmental issues, the impact of discarded plastic bags on human life has become a major concern. Numerous studies have found that discarded plastic bags, due to their non-degradability, contribute to white pollution, a problem that pollutes the environment. General-purpose plastic bags typically take hundreds of years to decompose, causing long-term damage to the soil, affecting crop growth, and leading to reduced yields. Furthermore, scattered plastic can cause animals to ingest and die. In response to these problems, China officially implemented a plastic restriction order in 2008, requiring all supermarkets, shopping malls, and farmers' markets to charge for plastic shopping bags, prohibiting the free provision of plastic shopping bags, and banning the production, sale, and use of plastic shopping bags with a thickness of less than 0.025 mm nationwide. Based on this, biodegradable plastics have emerged as a solution.

[0003] Synthetic plastics possess good physicochemical properties and economic feasibility, leading to their widespread application in many fields. However, traditional petroleum-based plastics are difficult to degrade, and incineration or landfill disposal causes ecological degradation. Therefore, there is a need to develop biodegradable polymers to mitigate their negative environmental impact. Polylactic acid (PLA) is obtained by the condensation polymerization of small-molecule lactic acid from microbial fermentation of biomass raw materials such as corn or sugarcane. It is non-toxic, high-strength, high-modulus, and possesses good biocompatibility and processability, making it suitable for applications such as drug carriers, food packaging, and optoelectronic devices. It is currently considered one of the most promising biodegradable polymers. However, due to the high rigidity of the PLA molecular chain, it suffers from defects such as high brittleness, low toughness, poor thermal stability, and poor impact resistance, limiting its applications. Summary of the Invention

[0004] The purpose of this invention is to provide a biodegradable high-strength plastic bag and its preparation method, thereby solving the following technical problems:

[0005] Existing polylactic acid-based biodegradable plastic bags suffer from problems such as high brittleness, low toughness, and poor impact resistance.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A biodegradable high-strength plastic bag comprises at least the following parts by weight of raw materials:

[0008] Polylactic acid 40-60 parts, poly(butylene adipate / terephthalate) 20-35 parts, modified nano-calcium carbonate 5-15 parts, modified wood fiber 3-8 parts, chitosan-grafted poly(glycidyl methacrylate) nanoparticles 6-8 parts, lubricant 0.5-2 parts, antioxidant 0.3-1 part, degradation promoter 2-5 parts, UV stabilizer 0.5-1.5 parts.

[0009] As a further aspect of the present invention, the preparation method of the chitosan-grafted polyglycidyl methacrylate nanoparticles includes the following steps:

[0010] Sodium tripolyphosphate solution was added to chitosan solution, and chitosan cross-linked nanoparticles were obtained after the reaction.

[0011] Glycidyl methacrylate was added to the chitosan cross-linked nanoparticles, followed by the addition of a nitric acid solution of cerium ammonium nitrate. After the reaction, chitosan-grafted poly(glycidyl methacrylate) nanoparticles were obtained.

[0012] As a further aspect of the present invention, the mass ratio of the chitosan to the sodium tripolyphosphate is 2-4:1.

[0013] As a further aspect of the present invention: the mass ratio of the chitosan cross-linked nanoparticles, the glycidyl methacrylate, and the cerium ammonium nitrate is 10:15-20:0.5-1.

[0014] As a further aspect of the present invention: the modified nano-calcium carbonate is γ-methacryloxypropyltrimethoxysilane modified nano-calcium carbonate.

[0015] As a further aspect of the present invention: the mass ratio of the calcium carbonate to the γ-methacryloyloxypropyltrimethoxysilane is 100:4-6.

[0016] As a further aspect of the present invention: the modified wood fiber is γ-methacryloyloxypropyltrimethoxysilane modified wood fiber.

[0017] As a further aspect of the present invention: the mass ratio of the wood fiber to the γ-methacryloyloxypropyltrimethoxysilane is 100:3-5.

[0018] As a further aspect of the present invention: the lubricant is one or more of stearic acid, stearate, polyvinyl chloride wax, white oil, paraffin, oleamide or erucamide; the antioxidant is one or a mixture of antioxidant 1010, antioxidant 1076 or antioxidant 168; the degradation promoter is one or a mixture of citric acid, tartaric acid, malic acid, oxalic acid, malonic acid, succinic anhydride or coconut shell activated carbon; and the ultraviolet stabilizer is one or a mixture of 1,2,2,4-tetra(4-carbonyloxy-2,2,6,6-tetramethylguanidine)-amine, 2-benzotriazole-ethyl-4,6-di-tert-butylphenol or benzoate-based ultraviolet stabilizers.

[0019] A method for preparing a biodegradable high-strength plastic bag includes at least the following preparation steps:

[0020] A premix was prepared by mixing polylactic acid, polybutylene adipate / terephthalate, modified nano-calcium carbonate, modified wood fiber, and chitosan-grafted polyglycidyl methacrylate nanoparticles.

[0021] The premix, lubricant, antioxidant, degradation accelerator and UV stabilizer are subjected to twin-screw extrusion to obtain composite particles;

[0022] The composite particles are blow-molded and packaged to prepare antibacterial, high-strength, biodegradable plastic bags.

[0023] The beneficial effects of this invention are:

[0024] This invention uses polylactic acid (PLA) and polybutylene terephthalate (PET) as base materials. PET toughens PLA, exhibiting excellent biodegradability, environmental friendliness, and no pollution or burden on the environment. Modified nano-calcium carbonate and modified fibers are used as fillers to improve the mechanical properties of the composite material. Chitosan-grafted glycidyl methacrylate (GMMA) nanoparticles are used as compatibilizers to effectively compatibilize the PLA and PET blend. This invention achieves a balance between high strength and biodegradability through interfacial crosslinking of chitosan-grafted GMMA nanoparticles and reinforcement with inorganic fillers. It overcomes the shortcomings of traditional fillers, such as poor compatibility with degradable resins and low reinforcing effect, while also considering the toughness and strength of the material. The resulting biodegradable high-strength plastic bag can be used as a high-performance flexible packaging material.

[0025] In this invention, the dispersion size of chitosan particles is reduced by ionic crosslinking, followed by surface-initiated graft polymerization to obtain chitosan-grafted poly(glycidyl methacrylate) nanoparticles. This introduces reactive compatibilizing groups into the chitosan. The grafted chains in the chitosan-grafted poly(glycidyl methacrylate) nanoparticles contain a large number of epoxy side groups. During melt blending, they can undergo esterification with polylactic acid and polybutylene terephthalate (PET) to form polylactic acid-chitosan-PET copolymer in situ, thereby playing a compatibilizing role, increasing the strength of the system, and making the toughening effect of PET more obvious. This effectively improves the shortcomings of existing polylactic acid and PET blend films, such as poor compatibility and poor mechanical properties of composite materials, and takes into account comprehensive performance.

[0026] This invention also incorporates calcium carbonate and wood fiber. The wood fiber and rigid calcium carbonate particles form a "fiber-particle" dual-reinforcing network, significantly improving tensile strength. The addition of calcium carbonate and wood fiber to the matrix has a synergistic reinforcing effect, forming a three-dimensional cross-linked network of "wood fiber-calcium carbonate-matrix," resulting in a significant improvement in mechanical properties. Furthermore, this invention uses γ-methacryloyloxypropyltrimethoxysilane to surface-modify calcium carbonate and wood fiber. After hydrolysis, the siloxy groups in γ-methacryloyloxypropyltrimethoxysilane adsorb onto the surface of calcium carbonate and wood fiber, forming chemical bonds with high bond energy and strong bonding. This maximizes the improvement of the interfacial compatibility between calcium carbonate and wood fiber and polylactic acid, resulting in a relatively significant improvement in the toughness of the composite material. Moreover, the methacryloyloxy groups in γ-methacryloyloxypropyltrimethoxysilane covalently cross-link with the epoxy groups in chitosan-grafted poly(glycidyl methacrylate) nanoparticles, achieving a strong interfacial bond between the filler and the matrix, further improving the toughness and strength of the prepared biodegradable high-strength plastic bag. Detailed Implementation

[0027] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] Example 1: The preparation method of modified silica includes the following steps:

[0029] Chitosan was dissolved in 1% acetic acid to prepare a 3 mg / mL chitosan solution. Then, 0.8 mg / mL sodium tripolyphosphate solution was added to the above solution, and the mass ratio of chitosan CS to sodium tripolyphosphate was controlled at 3:1. The mixture was stirred at room temperature for 1 h, then centrifuged 3 times. The precipitate was placed in a -80℃ freezer for 2 h and then freeze-dried for 36 h to obtain chitosan cross-linked nanoparticles.

[0030] 10 g of chitosan cross-linked nanoparticles were ultrasonically dispersed in 200 mL of deionized water in a 250 mL single-necked flask. Nitrogen gas was slowly bubbled through the flask for 1 h at room temperature. Then, 15 g of glycidyl methacrylate was added and the mixture was stirred continuously for 30 min. Subsequently, 5 mL of nitric acid solution (0.5 mol / L) containing 0.5 g of cerium ammonium nitrate was added. The flask was sealed and placed in a constant-temperature oil bath at 50 °C with continuous stirring for 5 h. After the reaction was complete, the solid product was separated by filtration, washed several times with tetrahydrofuran, and finally repeatedly washed with deionized water until neutral. The product was then freeze-dried to obtain chitosan-grafted glycidyl methacrylate nanoparticles.

[0031] Example 2: The preparation method of modified nano-calcium carbonate includes the following steps:

[0032] In a 1000 mL single-necked flask, ethanol and water were added sequentially in a 9:1 volume ratio. 50 mL of glacial acetic acid was added to adjust the pH of the mixture to 8. Then, 100 g of nano-calcium carbonate, 1 g of hydroquinone, and 3 g of γ-methacryloyloxypropyltrimethoxysilane were added sequentially. The mixture was sonicated for 30 min, and then heated in an oil bath to 80 °C for 24 h. After cooling to room temperature, the mixture was centrifuged at low speed and washed with ethanol. This process was repeated twice to remove residual silane coupling agent. The mixture was then vacuum dried for 24 h to obtain modified nano-calcium carbonate.

[0033] Example 3: The preparation method of modified wood fiber includes the following steps:

[0034] 100g of wood fiber (SQMC-3) was soaked in a 5wt% NaOH solution for 4 hours, then rinsed with deionized water until neutral, air-dried at room temperature, and then dried in a vacuum drying oven at 90℃ for 24 hours to obtain alkali-treated wood fiber.

[0035] 4g of γ-methacryloxypropyltrimethoxysilane was added to an ethanol-water solution containing 180mL of ethanol and 20mL of water to prepare a 2% silane coupling agent solution. The pH was adjusted to 4 with acetic acid, and the solution was stirred and hydrolyzed. The wood fiber was then treated with the above-mentioned alkali and stirred for 1 hour. The fiber was then washed with distilled water, vacuum dried at 60℃ for 12 hours, and then heated to 90℃ and dried for another 24 hours to obtain modified wood fiber.

[0036] Example 4: A biodegradable high-strength plastic bag, made by the following method:

[0037] 40 parts by weight of polylactic acid (4032D), 20 parts by weight of poly(butylene adipate / terephthalate) (TH801 T), 15 parts by weight of modified nano-calcium carbonate prepared in Example 2, 5 parts by weight of modified wood fiber prepared in Example 3, and 7 parts by weight of chitosan-grafted poly(glycidyl methacrylate) nanoparticles prepared in Example 1 were mixed to obtain a premix.

[0038] The above premix, 1 part by weight of stearic acid, 1 part by weight of antioxidant 1010, 2 parts by weight of citric acid and 1 part by weight of benzoate-based UV stabilizer were added to a twin-screw extruder. The length-to-diameter ratio was set to 40:1, the speed was 300 rpm, and the temperature gradient was 160℃ in zone 1, 170℃ in zone 2, 175℃ in zone 3, 180℃ in zone 4 and 175℃ in the die head to obtain composite particles.

[0039] The composite granules are added to the blown film unit, and the temperature is set as follows: Zone 1: 165℃, Zone 2: 170℃, Zone 3: 175℃, and Die Head: 175℃. The blow ratio is 2.5:1, the traction speed is 15m / min, the cooling roller temperature is 25℃, and the winding tension is 50N. The blown film is then processed and packaged to obtain a biodegradable high-strength plastic bag.

[0040] Example 5: A biodegradable high-strength plastic bag, made by the following method:

[0041] 45 parts by weight of polylactic acid (4032D), 25 parts by weight of poly(butylene adipate / terephthalate) (TH801 T), 15 parts by weight of modified nano-calcium carbonate prepared in Example 2, 5 parts by weight of modified wood fiber prepared in Example 3, and 7 parts by weight of chitosan-grafted poly(glycidyl methacrylate) nanoparticles prepared in Example 1 were mixed to obtain a premix.

[0042] The above premix, 1 part by weight of stearic acid, 1 part by weight of antioxidant 1010, 2 parts by weight of citric acid and 1 part by weight of benzoate-based UV stabilizer were added to a twin-screw extruder. The length-to-diameter ratio was set to 40:1, the speed was 300 rpm, and the temperature gradient was 160℃ in zone 1, 170℃ in zone 2, 175℃ in zone 3, 180℃ in zone 4 and 175℃ in the die head to obtain composite particles.

[0043] The composite granules are added to the blown film unit, and the temperature is set as follows: Zone 1: 165℃, Zone 2: 170℃, Zone 3: 175℃, and Die Head: 175℃. The blow ratio is 2.5:1, the traction speed is 15m / min, the cooling roller temperature is 25℃, and the winding tension is 50N. The blown film is then processed and packaged to obtain a biodegradable high-strength plastic bag.

[0044] Example 6: A biodegradable high-strength plastic bag, made by the following method:

[0045] 50 parts by weight of polylactic acid (4032D), 30 parts by weight of poly(butylene adipate / terephthalate) (TH801 T), 12 parts by weight of modified nano-calcium carbonate prepared in Example 2, 8 parts by weight of modified wood fiber prepared in Example 3, and 6 parts by weight of chitosan-grafted poly(glycidyl methacrylate) nanoparticles prepared in Example 1 were mixed to obtain a premix.

[0046] The above premix, 1 part by weight of stearic acid, 1 part by weight of antioxidant 1010, 2 parts by weight of citric acid and 1 part by weight of benzoate-based UV stabilizer were added to a twin-screw extruder. The length-to-diameter ratio was set to 40:1, the speed was 300 rpm, and the temperature gradient was 160℃ in zone 1, 170℃ in zone 2, 175℃ in zone 3, 180℃ in zone 4 and 175℃ in the die head to obtain composite particles.

[0047] The composite granules are added to the blown film unit, and the temperature is set as follows: Zone 1: 165℃, Zone 2: 170℃, Zone 3: 175℃, and Die Head: 175℃. The blow ratio is 2.5:1, the traction speed is 15m / min, the cooling roller temperature is 25℃, and the winding tension is 50N. The blown film is then processed and packaged to obtain a biodegradable high-strength plastic bag.

[0048] Example 7: A biodegradable high-strength plastic bag, made by the following method:

[0049] 60 parts by weight of polylactic acid (4032D), 35 parts by weight of poly(butylene adipate / terephthalate) (TH801 T), 12 parts by weight of modified nano-calcium carbonate prepared in Example 2, 8 parts by weight of modified wood fiber prepared in Example 3, and 6 parts by weight of chitosan-grafted poly(glycidyl methacrylate) nanoparticles prepared in Example 1 were mixed to obtain a premix.

[0050] The above premix, 1 part by weight of stearic acid, 1 part by weight of antioxidant 1010, 2 parts by weight of citric acid and 1 part by weight of benzoate-based UV stabilizer were added to a twin-screw extruder. The length-to-diameter ratio was set to 40:1, the speed was 300 rpm, and the temperature gradient was 160℃ in zone 1, 170℃ in zone 2, 175℃ in zone 3, 180℃ in zone 4 and 175℃ in the die head to obtain composite particles.

[0051] The composite granules are added to the blown film unit, and the temperature is set as follows: Zone 1: 165℃, Zone 2: 170℃, Zone 3: 175℃, and Die Head: 175℃. The blow ratio is 2.5:1, the traction speed is 15m / min, the cooling roller temperature is 25℃, and the winding tension is 50N. The blown film is then processed and packaged to obtain a biodegradable high-strength plastic bag.

[0052] Compared with Example 4, Comparative Example 1 did not include the chitosan-grafted polyglycidyl methacrylate nanoparticles prepared in Example 1, but the remaining components and preparation methods were completely consistent with Example 4.

[0053] Compared with Example 4, Comparative Example 2 only replaced the modified wood fiber prepared in Example 3 with the modified calcium carbonate prepared in Example 2. The other components and preparation methods were completely the same as those in Example 4.

[0054] Compared with Example 4, Comparative Example 3 only replaced the modified calcium carbonate prepared in Example 2 with the modified wood fiber prepared in Example 3. The other components and preparation methods were completely the same as those in Example 4.

[0055] Performance testing

[0056] Tensile property testing: A universal testing machine was used, and the test was conducted in accordance with GB / T 1040.3—2006 (Determination of tensile properties of plastics, Part 3: Test conditions for films and sheets). The biodegradable high-strength plastic bag products obtained in Examples 4-7 and Comparative Examples 1-3 were cut into strips of 150mm × 25mm and tensile tests were performed at speeds of 20mm / min and 50mm / min to test the tensile strength and elongation at break. The test results are shown in Table 1.

[0057] Right-angle tear strength test: A universal testing machine was used, and the test was conducted according to QB / T 1130-1991. The biodegradable high-strength plastic bag products obtained in Examples 4-7 and Comparative Examples 1-3 were cut into strips with a length (MD direction) of 100 mm and a width of 25 mm. A 30 mm cut was made along the length direction from the middle on one side of the width. The strips were then tested at room temperature using an Instron Mode l-1211 material testing machine with a tensile rate of 10 mm / min and a test number of n = 3. The results are expressed as the average value. The test results are shown in Table 1.

[0058] Impact performance testing: The test was conducted using a cantilever beam impact testing machine, in accordance with the national standard GB / T1843-2008. The impact test specimens were made into rectangles of 80.0mm × 12.5mm × 4.0mm, and a V-shaped notch was milled using a notching sample making machine. The notch depth was 20% of the specimen width. The test results were taken as the average value of 5 specimens. The test results are shown in Table 1.

[0059] Degradation test: Take an appropriate amount of outdoor soil, place a sufficient amount of composite material block sample dried to constant weight in the soil, add an appropriate amount of tap water regularly to maintain humidity, take out the sample after 180 days, wash it clean, dry it thoroughly and weigh it, and calculate the degradation rate; the test results are shown in Table 1.

[0060] Table 1: Statistical table of performance test data of plastic bags in Examples 4-7 and Comparative Examples 1-3

[0061]

[0062] As shown in Table 1, the biodegradable high-strength plastic bags prepared by this invention possess high strength and toughness, good degradation performance, and are suitable for high-end packaging, agricultural films, and medical fields. Comparative Example 1, without the addition of chitosan-grafted polyglycidyl methacrylate nanoparticles, resulted in the worst mechanical properties of the biodegradable high-strength plastic bag. Comparative Example 2, with only modified calcium carbonate and no modified wood fiber, showed a decrease in tensile properties. Comparative Example 3, with only modified wood fiber and no modified calcium carbonate, significantly reduced the impact strength of the biodegradable high-strength plastic bag. This indicates that the chitosan-grafted polyglycidyl methacrylate nanoparticles added in this invention can improve the compatibility between polylactic acid and poly(adipic acid / butylene terephthalate), and also improve the dispersibility of the filler, which is beneficial to the mechanical properties of the prepared plastic bags. The added modified calcium carbonate and modified wood fiber have a synergistic effect; their combined use has a better effect on modifying the material properties.

[0063] The foregoing has provided a detailed description of one embodiment of the present invention, but this description is merely a preferred embodiment and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the patent coverage of this invention.

Claims

1. A biodegradable high-strength plastic bag, characterized in that, It shall include at least the following parts by weight of raw materials: Polylactic acid 40-60 parts, poly(butylene adipate / terephthalate) 20-35 parts, modified nano-calcium carbonate 5-15 parts, modified wood fiber 3-8 parts, chitosan-grafted poly(glycidyl methacrylate) nanoparticles 6-8 parts, lubricant 0.5-2 parts, antioxidant 0.3-1 part, degradation promoter 2-5 parts, UV stabilizer 0.5-1.5 parts.

2. The biodegradable high-strength plastic bag according to claim 1, characterized in that, The preparation method of the chitosan-grafted polyglycidyl methacrylate nanoparticles includes the following steps: Sodium tripolyphosphate solution was added to chitosan solution, and chitosan cross-linked nanoparticles were obtained after the reaction. Glycidyl methacrylate was added to the chitosan cross-linked nanoparticles, followed by the addition of a nitric acid solution of cerium ammonium nitrate. After the reaction, chitosan-grafted poly(glycidyl methacrylate) nanoparticles were obtained.

3. The biodegradable high-strength plastic bag according to claim 2, characterized in that, The mass ratio of chitosan to sodium tripolyphosphate is 2-4:

1.

4. A biodegradable high-strength plastic bag according to claim 2, characterized in that, The mass ratio of the chitosan cross-linked nanoparticles, the glycidyl methacrylate, and the cerium ammonium nitrate is 10:15-20:0.5-1.

5. A biodegradable high-strength plastic bag according to claim 1, characterized in that, The modified nano-calcium carbonate is γ-methacryloyloxypropyltrimethoxysilane modified nano-calcium carbonate.

6. A biodegradable high-strength plastic bag according to claim 5, characterized in that, The mass ratio of the calcium carbonate to the γ-methacryloyloxypropyltrimethoxysilane is 100:4-6.

7. A biodegradable high-strength plastic bag according to claim 1, characterized in that, The modified wood fiber is γ-methacryloyloxypropyltrimethoxysilane modified wood fiber.

8. A biodegradable high-strength plastic bag according to claim 7, characterized in that, The mass ratio of the wood fiber to the γ-methacryloyloxypropyltrimethoxysilane is 100:3-5.

9. A biodegradable high-strength plastic bag according to claim 1, characterized in that, The lubricant is one or more of stearic acid, stearate, polyvinyl chloride wax, white oil, paraffin, oleamide, or erucamide; the antioxidant is one or a mixture of antioxidant 1010, antioxidant 1076, or antioxidant 168; the degradation promoter is one or a mixture of citric acid, tartaric acid, malic acid, oxalic acid, malonic acid, succinic anhydride, or coconut shell activated carbon; and the ultraviolet stabilizer is one or a mixture of 1,2,2,4-tetra(4-carbonyloxy-2,2,6,6-tetramethylguanidine)-amine, 2-benzotriazole-ethyl-4,6-di-tert-butylphenol, or benzoate-based ultraviolet stabilizers.

10. A method for preparing a biodegradable high-strength plastic bag, characterized in that, It includes at least the following preparation steps: A premix was prepared by mixing polylactic acid, polybutylene adipate / terephthalate, modified nano-calcium carbonate, modified wood fiber, and chitosan-grafted polyglycidyl methacrylate nanoparticles. The premix, lubricant, antioxidant, degradation accelerator and UV stabilizer are subjected to twin-screw extrusion to obtain composite particles; The composite particles are blow-molded and packaged to prepare antibacterial, high-strength, biodegradable plastic bags.

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