An antibacterial co-extruded PE film and its preparation method

Abstract

The present invention discloses an antibacterial co-extruded PE film and a preparation method thereof, belonging to the technical field of PE co-extruded films. It includes an antibacterial layer, a core layer, and a barrier layer, and the core layer is located between the antibacterial layer and the barrier layer. The antibacterial layer, the core layer, and the barrier layer are co-extruded to obtain a co-extruded PE film, which has good water vapor barrier performance. An ethylene-vinyl alcohol copolymer is added to the barrier layer material, endowing the PE film with excellent oxygen barrier performance; by modifying carbon nanotubes, the compatibility with the PE matrix is better, greatly enhancing the antistatic performance and mechanical properties of the PE film; in addition, the organic molecular chains grafted on the modified carbon nanotubes can also significantly enhance the antibacterial performance of the PE film and the mechanical properties and antistatic performance to a certain extent, and the performance is long-term stable; therefore, the co-extruded PE film prepared by the present invention has excellent barrier performance, high mechanical properties, and stable and efficient antistatic and antibacterial properties, and has important application value in the technical field of PE co-extruded films.

Description

Technical Field

[0001] The present invention belongs to the technical field of PE coextruded films, and specifically, relates to an antibacterial coextruded PE film and a preparation method thereof. Background Art

[0002] Polyethylene (PE) has good chemical stability, puncture resistance and impact resistance, especially good low-temperature resistance, and the embrittlement temperature can generally reach below -50°C. PE has good processing performance and a wide processing temperature range. Also, due to its rich raw material resources, moderate price and excellent comprehensive product performance, its application scope is gradually expanding, especially in the packaging field.

[0003] The PE coextruded film is a multi-layer composite film made by coextrusion casting process with different types of polyethylene raw materials. This material has good transparency, puncture resistance, appropriate friction coefficient, composite performance, excellent hot tackiness and anti-pollution heat-sealing performance. The PE coextruded film has good water vapor barrier property, but poor oxygen barrier property, and cannot well prevent the permeation of oxygen in the external environment, which will cause the product to be oxidized through the packaging. In addition, since the PE material has a non-polar molecular structure, the molecular chain composed of its covalent bonds can neither ionize nor easily transfer free electrons. Once charged due to friction and electron gain or loss, it is very difficult to eliminate. The static electricity generated during the processing of PE materials brings many inconveniences to the further processing of packaging film materials, affecting the operability of the products and the printing effect when the film is used for packaging due to static interference, and it is difficult to separate or seal the bags after being made. In severe cases, it will even cause electric shock. Moreover, the antibacterial property of PE materials is poor. When exposed to air for a long time, bacteria in the air will grow on the surface of the packaging film, endangering people's health. Therefore, there is an urgent need to invent a coextruded PE film with excellent antibacterial and antistatic properties and good barrier properties to meet the higher requirements in the technical field of PE coextruded films. Summary of the Invention

[0004] The purpose of the present invention is to overcome the defects of the prior art and provide an antibacterial coextruded PE film and a preparation method thereof.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] An antibacterial coextruded PE film includes an antibacterial layer, a core layer and a barrier layer, and the core layer is located between the antibacterial layer and the barrier layer.

[0007] Further, the antibacterial layer accounts for 20 - 30% of the thickness of the PE film and is composed of the following raw materials in parts by weight: 80 - 100 parts of linear low-density polyethylene, 6 - 24 parts of modified carbon nanotubes, 3 - 5 parts of paraffin wax, and 4 - 8 parts of antioxidant 264.

[0008] Further, the core layer accounts for 45 - 65% of the thickness of the PE film and is composed of the following raw materials in parts by weight: 60 - 70 parts of linear low-density polyethylene and 20 - 30 parts of low-density polyethylene.

[0009] Further, the barrier layer accounts for 15 - 25% of the thickness of the PE film and is composed of the following raw materials in parts by weight: 70 - 80 parts of linear low-density polyethylene and 10 - 20 parts of ethylene-vinyl alcohol copolymer.

[0010] An antibacterial coextruded PE film is prepared through the following steps:

[0011] Add the antibacterial layer material, core layer material, and barrier layer material into three extruders respectively for melt processing, coextrude them through a die head into a three-layer coextruded structure, cool and form, then conduct longitudinal stretching, transverse stretching, heat setting, and winding to obtain the antibacterial coextruded PE film.

[0012] Further, the temperature in the molten state is set at 200°C - 240°C, and the temperature of the die head is set at 220°C - 260°C.

[0013] Coextrude the antibacterial layer, core layer, and barrier layer to obtain the coextruded PE film. Polyethylene endows the coextruded PE film with good water vapor barrier performance. The ethylene-vinyl alcohol copolymer has good processing performance and can also endow the PE film with good oxygen barrier performance.

[0014] Further, the modified carbon nanotubes are prepared through the following steps:

[0015] S1. In a three-necked flask equipped with a stirring device, dissolve triphenylphosphine (PPh3) in toluene, slowly add chloroacetaldehyde dropwise, and raise the temperature to 50°C, stir and react for 2 h. After the reaction ends, remove the solvent by vacuum distillation to obtain intermediate 1. The dosage ratio of triphenylphosphine, toluene, and chloroacetaldehyde is 26.2 g:100 mL:7.7 g;

[0016] Triphenylphosphine reacts with the chloro group of chloroacetaldehyde to obtain the quaternary phosphonium product intermediate 1. The specific reaction process is as follows:

[0017]

[0018] S2. In a three-necked flask equipped with a stirring device, add Intermediate 1 and N,N-dimethylformamide (DMF). After stirring evenly, add diethylenetriamine and piperidine (condensing agent), stir and mix evenly. Control the reaction temperature at 75 °C, keep the temperature for 4 h. After the reaction is completed, distill off part of the solvent under reduced pressure, and then purify by column chromatography (the eluent is a mixed solvent of ethyl acetate / methanol, and the volume ratio of the two is 3:2). Rotate and evaporate to remove the eluent to obtain Intermediate 2; the dosage ratio of Intermediate 1, N,N-dimethylformamide, diethylenetriamine, and piperidine is 32.4 g:100 mL:11.4 g:15 mL;

[0019] Under the action of the condensing agent, the aldehyde group on Intermediate 1 condenses with the amino group on diethylenetriamine to form an imino group (C=N Schiff base structure). By controlling the molar ratio of the two to be close to 1:1 and diethylenetriamine being slightly in excess, Intermediate 2 is obtained; the specific reaction process is as follows:

[0020]

[0021] S3. In a three-necked flask equipped with a stirring device, mix carboxylated carbon nanotubes with N,N-dimethylformamide, and ultrasonicate for 30 min to disperse the carboxylated carbon nanotubes evenly. Then add Intermediate 2 and dicyclohexylcarbodiimide (DCC), stir magnetically for 2 h, place it in a 65 °C water bath and ultrasonicate for 2 h, then remove the water bath and stir magnetically at room temperature for 8 h, filter by suction, wash with absolute ethanol 3-4 times, dry, and grind to obtain pre-modified carbon nanotubes; the dosage ratio of carboxylated carbon nanotubes, N,N-dimethylformamide, Intermediate 2, and DCC is 5 g:100 mL:7.5 g:13.7 g;

[0022] Under the action of DCC, the -COOH on the surface of carboxylated carbon nanotubes reacts with the -NH2 on Intermediate 2 to undergo an amidation reaction, grafting organic molecules on the surface of the carbon nanotubes to obtain pre-modified carbon nanotubes; the specific reaction process is as follows:

[0023]

[0024] S4. At room temperature, under nitrogen protection, in a three-necked flask equipped with a stirring device, mix the pre-modified carbon nanotubes with N,N-dimethylformamide, ultrasonicate for 30 min to disperse the carboxylated carbon nanotubes evenly, add 8-chloro-1-octene and triethylamine, turn on magnetic stirring, control the reaction temperature at 80 °C, keep the temperature for 12 h. After the reaction is completed, filter by suction, take the filter residue, wash with absolute ethanol 3-4 times, dry, and grind to obtain modified carbon nanotubes; the dosage ratio of pre-modified carbon nanotubes, N,N-dimethylformamide, 8-chloro-1-octene, and triethylamine is 5 g:100 mL:4.5 g:20 mL;

[0025] Triethylamine is used as an acid-binding agent to remove the hydrogen chloride generated by the reaction, accelerating the progress of the reaction. The secondary amino group on the pre-modified carbon nanotubes undergoes a nucleophilic substitution reaction with the chloro group on 8-chloro-1-octene to obtain modified carbon nanotubes;

[0026] The prepared modified carbon nanotubes graft organic molecular chains through chemical bonding, that is, an organic layer is formed on its surface, which can greatly improve the interfacial compatibility between the carbon nanotubes and the matrix, reduce the agglomeration phenomenon of the carbon nanotubes, thereby promoting the uniform dispersion of the modified carbon nanotubes in the matrix, giving full play to the antistatic performance of the carbon nanotubes, and also enhancing the matrix; moreover, grafting organic molecular chains on the carbon nanotubes can effectively prevent the migration and exudation of organic molecules, ensuring the durability of various properties; in addition, the organic molecular chain contains quaternary phosphonium salts, Schiff bases, long carbon chains and carbon-carbon double bond structures. Among them, the quaternary phosphonium salt functional group, where the positively charged phosphonium ion adsorbs on the surface of the bacteria, can interact with the negatively charged cell membrane of the bacteria, penetrate the cell wall, combine with the cell membrane, destroy the surface structure of the cell, cause the outflow of intracellular substances, and the respiratory function of the bacteria stops leading to cell death, not only enhancing the antibacterial performance of the matrix, but also having better antibacterial activity than quaternary ammonium salts, and also enhancing the antistatic performance of the matrix to a certain extent; moreover, the C=N Schiff base structure can interact with the proteins and enzymes of bacteria, hinder the synthesis of bacterial nucleotides and amino acids, and play a synergistic role with the quaternary phosphonium salt, greatly enhancing the antibacterial performance of the matrix; the long carbon chain belongs to a flexible chain segment, which can improve the mechanical properties of the matrix and can penetrate into the molecular chain of the matrix to enhance stability; in addition, the long carbon chain can also enhance the antibacterial property of the quaternary phosphonium salt, and belongs to a hydrophobic chain, which can further enhance the surface hydrophobicity of the carbon nanotubes and improve the compatibility with the matrix; finally, one end of the modified carbon nanotubes contains a carbon-carbon double bond, which can crosslink with the matrix, enabling the modified carbon nanotubes to be combined with the matrix in a chemical bond block manner, thereby improving the binding force between the modified carbon nanotubes and the matrix and making the performance more stable.

[0027] Furthermore, the carboxylated carbon nanotubes are prepared by the following steps:

[0028] Place the carbon nanotubes in a conical flask, then add a mixed acid, ultrasonically treat in a water bath at 55 °C for 6 h. After the mixture is cooled to room temperature, add deionized water for dilution, centrifuge, and wash 4-5 times successively with absolute ethanol and deionized water, then dry and grind to obtain carboxylated carbon nanotubes; the mixed acid is a mixture prepared by mixing concentrated sulfuric acid with a mass fraction of 98% and concentrated hydrochloric acid with a mass fraction of 38.7% according to a volume ratio of 4:1; the dosage ratio of carbon nanotubes to the mixed acid is 1 g:100 mL;

[0029] Ultrasonic shearing and oxidation treatment of carbon nanotubes with strong acids can introduce a certain number of carboxyl active groups on the sidewalls and tops of the carbon nanotubes, laying a reaction site for subsequent chemical reactions.

[0030] Advantages of the present invention:

[0031] 1. By co-extruding three layers of an antibacterial layer, a core layer, and a barrier layer, a co-extruded PE film is prepared. It has good water vapor barrier performance. Ethylene-vinyl alcohol copolymer is added to the barrier layer material, endowing the PE film with excellent oxygen barrier performance;

[0032] 2. By modifying carbon nanotubes, compared with ordinary carbon nanotubes, they have better compatibility with the PE matrix, greatly enhancing the antistatic performance and mechanical properties of the PE film; in addition, the organic molecular chains grafted on the modified carbon nanotubes can also significantly enhance the antibacterial performance and, to a certain extent, the mechanical properties and antistatic performance of the PE film, and the performance is long-term stable;

[0033] Therefore, the co-extruded PE film prepared by the present invention has excellent barrier performance, high mechanical properties, and stable and efficient antistatic and antibacterial properties, and has important application value in the technical field of PE co-extruded films. Specific embodiments

[0034] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0035] Example 1

[0036] Preparation of carboxylated carbon nanotubes:

[0037] Put 20 g of carbon nanotubes into a conical flask, then add 2000 mL of a mixed acid prepared by mixing concentrated sulfuric acid (mass fraction 98%) and concentrated hydrochloric acid (mass fraction 38.7%) in a volume ratio of 4:1. Ultrasonically treat it in a water bath at 55°C for 6 h. After the mixture is cooled to room temperature, add deionized water for dilution, centrifuge, and wash it 4 times with anhydrous ethanol and deionized water in sequence, then dry and grind to obtain carboxylated carbon nanotubes.

[0038] Example 2

[0039] Preparation of modified carbon nanotubes:

[0040] S1. In a three-necked flask equipped with a stirring device, dissolve 26.2 g of triphenylphosphine in 100 mL of toluene, slowly dropwise add 7.7 g of chloroacetaldehyde, and raise the temperature to 50°C. Stir and react for 2 h. After the reaction is completed, remove the solvent by vacuum distillation to obtain Intermediate 1;

[0041] S2. In a three-necked flask equipped with a stirring device, add 32.4 g of Intermediate 1 and 100 mL of N,N-dimethylformamide. After stirring evenly, add 11.4 g of diethylenetriamine and 15 mL of piperidine, stir and mix evenly. Control the reaction temperature at 75 °C, keep the temperature for reaction for 4 h. After the reaction is completed, remove part of the solvent by vacuum distillation, and then purify by column chromatography (the eluent uses a mixed solvent of ethyl acetate / methanol, and the volume ratio of the two is 3:2). Rotavapor to remove the eluent to obtain Intermediate 2;

[0042] S3. In a three-necked flask equipped with a stirring device, mix 5 g of the carboxylated carbon nanotubes prepared in Example 1 with 100 mL of N,N-dimethylformamide, and ultrasonicate for 30 min to disperse the carboxylated carbon nanotubes evenly. Then add 7.5 g of Intermediate 2 and 13.7 g of dicyclohexylcarbodiimide, stir magnetically for 2 h, place it in a 65 °C water bath and ultrasonicate for 2 h, then remove the water bath and stir magnetically at room temperature for 8 h. Filter by suction, wash 3 times with absolute ethanol, dry, and grind to obtain pre-modified carbon nanotubes;

[0043] S4. At room temperature, under nitrogen protection, in a three-necked flask equipped with a stirring device, mix 5 g of pre-modified carbon nanotubes with 100 mL of N,N-dimethylformamide, and ultrasonicate for 30 min to disperse the carboxylated carbon nanotubes evenly. Add 4.5 g of 8-chloro-1-octene and 20 mL of triethylamine, turn on magnetic stirring, control the reaction temperature at 80 °C, keep the temperature for reaction for 12 h. After the reaction is completed, filter by suction, take the filter residue, wash 4 times with absolute ethanol, dry, and grind to obtain modified carbon nanotubes.

[0044] Example 3

[0045] Preparation of modified carbon nanotubes:

[0046] S1. In a three-necked flask equipped with a stirring device, dissolve 52.4 g of triphenylphosphine in 200 mL of toluene, slowly add 15.4 g of chloroacetaldehyde dropwise, and raise the temperature to 50 °C, stir and react for 2 h. After the reaction is completed, remove the solvent by vacuum distillation to obtain Intermediate 1;

[0047] S2. In a three-necked flask equipped with a stirring device, add 64.8 g of Intermediate 1 and 200 mL of N,N-dimethylformamide. After stirring evenly, add 22.8 g of diethylenetriamine and 30 mL of piperidine, stir and mix evenly. Control the reaction temperature at 75 °C, keep the temperature for reaction for 4 h. After the reaction is completed, remove part of the solvent by vacuum distillation, and then purify by column chromatography (the eluent uses a mixed solvent of ethyl acetate / methanol, and the volume ratio of the two is 3:2). Rotavapor to remove the eluent to obtain Intermediate 2;

[0048] S3. In a three-necked flask equipped with a stirring device, 10 g of the carboxylated carbon nanotubes prepared in Example 1 was mixed with 200 mL of N,N-dimethylformamide, and ultrasonicated for 30 min to uniformly disperse the carboxylated carbon nanotubes. Then, 15.0 g of Intermediate 2 and 27.4 g of dicyclohexylcarbodiimide were added, and magnetically stirred for 2 h. It was placed in a 65°C water bath and ultrasonicated for 2 h, and then the water bath was removed and magnetically stirred at room temperature for 8 h. It was filtered by suction, washed 3 times with absolute ethanol, dried, ground, and the pre-modified carbon nanotubes were obtained;

[0049] S4. At room temperature, under nitrogen protection, in a three-necked flask equipped with a stirring device, 10 g of the pre-modified carbon nanotubes was mixed with 200 mL of N,N-dimethylformamide, and ultrasonicated for 30 min to uniformly disperse the carboxylated carbon nanotubes. 9.0 g of 8-chloro-1-octene and 40 mL of triethylamine were added, the magnetic stirring was started, and the reaction temperature was controlled at 80°C. The reaction was carried out with heat preservation for 12 h. After the reaction was completed, it was filtered by suction, the filter residue was taken, washed 4 times with absolute ethanol, dried, ground, and the modified carbon nanotubes were obtained.

[0050] Example 4

[0051] For the antibacterial layer material: 80 g of linear low-density polyethylene, 6 g of the modified carbon nanotubes prepared in Example 2, 3 g of paraffin wax, 4 g of antioxidant 264, for the core layer material: 60 g of linear low-density polyethylene, 20 g of low-density polyethylene, and for the barrier layer material: 70 g of linear low-density polyethylene, 10 g of ethylene-vinyl alcohol copolymer were respectively added to three extruders and melt-processed at 200°C, and co-extruded into a three-layer co-extruded structure (the core layer is located between the antibacterial layer and the barrier layer) through a 220°C die head, cooled and formed, and then longitudinally stretched, transversely stretched, heat-set, and wound up to obtain an antibacterial co-extruded PE film. The thickness of the PE film was adjusted to 60 μm by controlling the traction speed.

[0052] Example 5

[0053] For the antibacterial layer material: 90 g of linear low-density polyethylene, 15 g of the modified carbon nanotubes prepared in Example 3, 4 g of paraffin wax, 6 g of antioxidant 264, for the core layer material: 65 g of linear low-density polyethylene, 25 g of low-density polyethylene, and for the barrier layer material: 75 g of linear low-density polyethylene, 15 g of ethylene-vinyl alcohol copolymer were respectively added to three extruders and melt-processed at 220°C, and co-extruded into a three-layer co-extruded structure (the core layer is located between the antibacterial layer and the barrier layer) through a 240°C die head, cooled and formed, and then longitudinally stretched, transversely stretched, heat-set, and wound up to obtain an antibacterial co-extruded PE film. The thickness of the PE film was adjusted to 60 μm by controlling the traction speed.

[0054] Example 6

[0055] Add the antibacterial layer materials: 100 g of linear low-density polyethylene, 24 g of modified carbon nanotubes prepared in Example 3, 5 g of paraffin wax, and 8 g of antioxidant 264, the core layer materials: 70 g of linear low-density polyethylene, 30 g of low-density polyethylene, and the barrier layer materials: 80 g of linear low-density polyethylene, 20 g of ethylene-vinyl alcohol copolymer into three extruders respectively, melt and process at 240 °C, and co-extrude through a 260 °C die to form a three-layer co-extruded structure (the core layer is located between the antibacterial layer and the barrier layer), cool and form, then conduct longitudinal stretching, transverse stretching, heat setting, and winding to obtain an antibacterial co-extruded PE film, and adjust the thickness of the PE film to 60 μm by controlling the traction speed.

[0056] Comparative Example 1

[0057] Use ordinary carbon nanotubes of the same mass to replace the modified carbon nanotubes in Example 6, and the remaining steps are the same as those in Example 6 to prepare a PE film, and adjust the thickness of the PE film to 60 μm by controlling the traction speed.

[0058] Comparative Example 2

[0059] Use commercially available quaternary ammonium salt antibacterial agent of the same mass to replace the modified carbon nanotubes in Example 6, and the remaining steps are the same as those in Example 6 to prepare a PE film, and adjust the thickness of the PE film to 60 μm by controlling the traction speed.

[0060] Make the corresponding shapes of Examples 4 - 6 and Comparative Examples 1 - 2 according to different test standards, and conduct the following performance tests:

[0061] Determine the tensile strength according to the national standard GB / T 1040.3 - 2006 "Plastics - Determination of tensile properties - Part 3: Test conditions for films and sheets";

[0062] Determine the surface resistivity according to the national standard GB / T 1410 - 2006 "Test methods for volume resistivity and surface resistivity of solid insulating materials";

[0063] Determine the oxygen permeability according to the national standard GB / T 1038 - 2022 "Test method for gas permeability of plastic films and sheets - Differential pressure method";

[0064] Determine the water vapor permeability according to the national standard GB / T 1037 - 2010 "Determination of water vapor transmission properties of plastic films and sheets - Cup method for weight gain and weight loss";

[0065] The national standard GB / T 31402-2015 "Test Method for Antibacterial Properties of Plastics on the Surface of Plastics" was adopted, and the film sticking method was used to detect the inhibitory effects on Escherichia coli and Staphylococcus aureus; the method is as follows: Inoculate Escherichia coli or Staphylococcus aureus on the plate medium, and after covering the film and storing for 24 hours, carry out viable bacteria culture; compare the parallel experimental results of the blank sample to obtain the antibacterial rate of the sample;

[0066] The antibacterial rate of the sample after being placed at room temperature for 180 days was measured using the same standard;

[0067] The measured results are shown in the following table:

[0068]

[0069]

[0070] As can be seen from the above table, the co-extruded PE film prepared in the embodiment of the present invention has higher antistatic property, antibacterial property and mechanical properties than the comparative example, and has excellent barrier property, and the performance is long-term stable, and has important application value in the technical field of PE co-extruded films.

[0071] In the description of the specification, the description referring to terms such as "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0072] The above content is only an example and illustration of the present invention. Those skilled in the art of this technology make various modifications or supplements to the described specific embodiments or use similar methods to replace them. As long as they do not deviate from the invention or exceed the scope defined by the claims of the present invention, they should all belong to the protection scope of the present invention.

Claims

1. An antibacterial co-extruded PE film, comprising an antibacterial layer, a core layer and a barrier layer, characterized in that, The raw materials of the material of the antibacterial layer are as follows by weight parts: 80-100 parts of linear low density polyethylene, 6-24 parts of modified carbon nanotubes, 3-5 parts of paraffin wax, 4-8 parts of antioxidant 264; Among them, the modified carbon nanotubes are prepared by the following steps: S1. Dissolve triphenylphosphine in toluene, slowly dropwise add chloroacetaldehyde, and raise the temperature to 50 °C, stir and react for 2 h. After the reaction is completed, carry out reduced pressure distillation to obtain intermediate 1; S2. After uniformly stirring intermediate 1 and N,N-dimethylformamide, then add diethylenetriamine and piperidine, stir and mix, react at 75 °C for 4 h. After the reaction is completed, carry out reduced pressure distillation, purify by column chromatography, and carry out rotary evaporation to obtain intermediate 2; S3. Mix carboxylated carbon nanotubes with N,N-dimethylformamide, ultrasonicate for 30 min, then add intermediate 2 and dicyclohexylcarbodiimide, magnetically stir for 2 h, ultrasonicate at 65 °C for 2 h, stir at room temperature for 8 h, carry out suction filtration, wash, dry, and grind to obtain pre-modified carbon nanotubes; S4. At room temperature, under nitrogen protection, mix pre-modified carbon nanotubes with N,N-dimethylformamide, ultrasonicate for 30 min, add 8-chloro-1-octene and triethylamine, turn on magnetic stirring, react at 80 °C for 12 h. After the reaction is completed, carry out suction filtration, take the filter residue, wash, dry, and grind to obtain modified carbon nanotubes; Among them, the dosage ratio of intermediate 1, N,N-dimethylformamide, diethylenetriamine, and piperidine in step S2 is 32.4 g:100 mL:11.4 g:15 mL.

2. The antibacterial coextruded PE film according to claim 1, wherein, The dosage ratio of triphenylphosphine, toluene, and chloroacetaldehyde in step S1 is 26.2 g:100 mL:7.7 g.

3. The antibacterial co-extruded PE film according to claim 1, wherein, The dosage ratio of carboxylated carbon nanotubes, N,N-dimethylformamide, intermediate 2, and dicyclohexylcarbodiimide in step S3 is 5 g:100 mL:7.5 g:13.7 g.

4. An antibacterial co-extruded PE film according to claim 1, characterized in that, The dosage ratio of pre-modified carbon nanotubes, N,N-dimethylformamide, 8-chloro-1-octene, and triethylamine in step S4 is 5 g:100 mL:4.5 g:20 mL.

5. An antibacterial coextruded PE film according to claim 1, characterized in that, The antibacterial layer accounts for 20-30% of the thickness of the PE film.

6. The antibacterial co-extruded PE film according to claim 1, characterized in that, The barrier layer accounts for 15-25% of the thickness of the PE film and is composed of the following raw materials by weight parts: 70-80 parts of linear low density polyethylene, 10-20 parts of ethylene-vinyl alcohol copolymer.

7. The preparation method of an antibacterial co-extruded PE film according to claim 1, wherein, Including the following steps: Respectively add the antibacterial layer material, the core layer material, and the barrier layer material into three extruders for melting and processing, co-extrude through a die head into a three-layer co-extrusion structure, cool and form, then carry out longitudinal stretching, transverse stretching, heat setting, and winding to obtain an antibacterial co-extruded PE film.

8. The preparation method of an antibacterial co-extruded PE film according to claim 7, characterized in that, The temperature in the molten state is set at 200 °C - 240 °C, and the temperature of the die head is set at 220 °C - 260 °C.

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