Environment-friendly antibacterial polyethylene film for packaging and preparation method thereof

Abstract

The invention relates to the field of films, and discloses an environment-friendly antibacterial polyethylene film for packaging and a preparation method thereof, the polyethylene film comprises low density polyethylene, a modified composite material, modified nano zinc oxide and a lubricant; the modified composite material is prepared by stripping hexagonal boron nitride by using tannic acid, loading titanium dioxide by using a sol-gel method, and then grafting polyhexamethylene biguanidine to the prepared titanium dioxide-hexagonal boron nitride nanosheet composite material by using chemical reaction. The modified nano-zinc oxide is prepared by loading chitosan phosphate onto the surface of nano-zinc oxide through intermolecular dehydration and then carrying out electrostatic self-assembly on the nano-zinc oxide and carboxylated silicone oil. The carboxylated silicone oil is prepared by carrying out hydrosilylation reaction on polymethylhydrosiloxane and methyl methacrylate and then carrying out ester group hydrolysis reaction. The film material prepared by the invention has excellent mechanical strength, water resistance, flame retardance and antibacterial property.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of thin films, and particularly relates to an environmentally-friendly antibacterial polyethylene film for packaging and a preparation method thereof. BACKGROUND

[0002] Polyethylene film has the characteristics of lightness, flexibility, transparency and moisture resistance, and is widely used in the packaging industry. High functionalization of polyethylene film can not only broaden the application field of polyethylene film, but also increase the competitiveness of polyethylene film in the high value-added market. In industry, the antibacterial functionalization of the film is usually achieved by adding antibacterial agents. Titanium dioxide and zinc oxide are ideal choices for antibacterial agents due to their low cost, long-term effectiveness and biocompatibility. However, in practical applications, the main method to improve the antibacterial activity of polyethylene film is to increase the content of antibacterial agents. However, this method not only increases the cost, but also has a negative impact on the mechanical properties of the polyethylene antibacterial film. In addition, in the antibacterial film of the blend, due to the incompatibility of inorganic compounds and polyolefins, the antibacterial agent often has problems of particle aggregation and poor distribution. In addition, the existing polyethylene film has the defects of insufficient water resistance and flame retardance, thereby limiting its application range, and the mechanical strength also needs to be further improved to meet the high performance requirements of plastic bag packaging. SUMMARY

[0003] To solve the problems mentioned in the background, the purpose of the present application is to provide an environmentally-friendly antibacterial polyethylene film for packaging and a preparation method thereof. By adding modified composite materials and modified nano-zinc oxide, the film material is endowed with excellent mechanical strength, water resistance, flame retardance and antibacterial properties.

[0004] The purpose of the present application can be achieved by the following technical solutions: An environmentally-friendly antibacterial polyethylene film for packaging, comprising the following components by weight: low-density polyethylene 85-100 parts, modified composite material 2-8 parts, modified nano-zinc oxide 1-5 parts, and lubricant 0.1-1 part. The modified composite material is prepared by peeling and functionalizing hexagonal boron nitride with tannic acid, and then loading titanium dioxide on the hexagonal boron nitride nanosheet composite material by sol-gel method, and then grafting polyhexamethylene biguanide on the prepared titanium dioxide-hexagonal boron nitride nanosheet composite material by chemical reaction; The modified nano-zinc oxide is prepared by loading chitosan phosphate onto the surface of nano-zinc oxide by intermolecular dehydration to prepare functionalized nano-zinc oxide, and then preparing the functionalized nano-zinc oxide and carboxylated silicone oil by electrostatic self-assembly method. The carboxylated silicone oil is prepared by ester hydrolysis reaction after the silicon-hydrogen addition reaction of polymethylhydrosiloxane and methyl propylate.

[0005] Preferably, the preparation method of the modified composite material comprises the following steps: I. The hexagonal boron nitride nanosheets are prepared by dispersing the hexagonal boron nitride in a tannic acid aqueous solution under ultrasonic condition, treating in an oil bath at 75-85℃ for 2-3h, and then treating in an ice bath under ultrasonic condition for 0.5-1h, removing the large unexfoliated hexagonal boron nitride by centrifugation, and then centrifuging, drying, and the like; II. The titanium dioxide-hexagonal boron nitride nanosheet composite material is prepared by stirring and mixing tetrabutyl titanate and anhydrous ethanol, then adding acetic acid and the hexagonal boron nitride nanosheets, ultrasonic dispersing for 8-12h, drying, calcining in a muffle furnace at a temperature increasing rate of 5℃ / min at 450-500℃ for 4-6h, and the like. III. The modified composite material is prepared by stirring and mixing the titanium dioxide-hexagonal boron nitride nanosheet composite material and a sodium hydroxide solution, then washing, ultrasonic dispersing in N,N-dimethylformamide, stirring and reacting for 0.5-1h after adding epichlorohydrin, then stirring and reacting for 1-2h after adding polyhexamethylene biguanide, and then centrifuging, washing, drying, and the like.

[0006] Preferably, the mass ratio of the titanium dioxide-hexagonal boron nitride nanosheet composite material and the polyhexamethylene biguanide is 1:1-4.

[0007] Preferably, the preparation method of the modified nanometer zinc oxide comprises the following steps: ①The anhydrous ethanol, phosphoric acid, and triethyl phosphate are mixed uniformly, then the diphosphorus pentoxide and chitosan are added, the mixture is heated and stirred in a water bath at 40-55℃ for 20-24h, then excess anhydrous methanol is added, and the precipitate obtained by filtration is washed and dried to prepare the chitosan phosphate powder; ②The chitosan phosphate powder is dissolved in a glacial acetic acid solution, then the nanometer zinc oxide is added, ultrasonic dispersing and stirring are performed for 20-24h, and then the functionalized nanometer zinc oxide is prepared by filtration, washing, and drying after the reaction is completed; ③The functionalized nanometer zinc oxide is ultrasonic dispersed in deionized water to obtain a suspension, carboxylated silicone oil is added to dilute ammonia water and the pH value is adjusted to 8, then the carboxylated silicone oil is added to the suspension, stirring is performed for 3-5min, and then the modified nanometer zinc oxide is prepared by centrifugation, washing, and drying.

[0008] Preferably, in step ①, the volume ratio of the anhydrous ethanol, phosphoric acid, and triethyl phosphate is 4:1:1; and the mass ratio of the diphosphorus pentoxide and chitosan is 0.7-0.9:1.

[0009] Preferably, in step ②, the mass ratio of the nanometer zinc oxide and the chitosan phosphate powder is 1:0.2-0.4.

[0010] Preferably, in step ③, the mass ratio of the functionalized nanometer zinc oxide and the carboxylated silicone oil is 1:0.05-0.2.

[0011] Preferably, the preparation method of the carboxylated silicone oil comprises the following steps: The carboxylated silicone oil is prepared by the following steps: taking polymethylhydrogen siloxane, toluene and a hexahydrate chloroplatinic acid solution into a reactor, heating to 75-85 DEG C under a nitrogen atmosphere, slowly adding methyl propionate, reacting at 140-145 DEG C for 24-30 hours, then distilling under reduced pressure, washing by centrifugation, placing the obtained product and a sodium hydroxide solution at 95-102 DEG C for hydrolysis for 1.5-2 hours, fractionating methanol, then dropping the reaction solution into a dilute hydrochloric acid solution to adjust the pH value to 6, washing and drying the precipitated solid product.

[0012] Preferably, the lubricant is one or a combination of both of stearic acid octadecanol ester or polyethylene wax.

[0013] The preparation method of the environmentally-friendly antibacterial polyethylene film for packaging as described above comprises the following steps: S1, each component is weighed by weight parts, and low-density polyethylene, modified composite material, modified nano zinc oxide and lubricant are mechanically blended to obtain a premix; S2, the premix is melt-extruded and water-cooled and granulated by a double-screw granulator, the double-screw range is set to 150-200 DEG C, and a mixture is obtained; S3, the mixture is added to an extrusion casting machine, the screw temperature range is set to 140-190 DEG C, and the environmentally-friendly antibacterial polyethylene film for packaging is prepared.

[0014] The present application has the following advantages: The present application adopts tannic acid to peel and functionalize hexagonal boron nitride, and loads titanium dioxide by a sol-gel method to prepare a titanium dioxide-hexagonal boron nitride nanosheet composite material. The hexagonal boron nitride, as a two-dimensional nanomaterial, has excellent thermal stability, high hydrophobicity, high adhesion and excellent mechanical strength. The titanium dioxide has good broad-spectrum antibacterial property and chemical stability. The loading of the titanium dioxide by the sol-gel method is beneficial to the uniform dispersion of the titanium dioxide particles, and the composite material has antibacterial property and mechanical property. The polyhexamethylene biguanide with excellent antibacterial activity is grafted on the surface of the titanium dioxide-hexagonal boron nitride nanosheet composite material by a chemical reaction, which is beneficial to further improving the antibacterial property of the film material. The introduction of the organic functional group can improve the compatibility of the composite material with the matrix and the interface bonding between the nanoparticles and the matrix material, so as to better play the comprehensive performance.

[0015] The application utilizes intermolecular dehydration to load chitosan phosphate onto the surface of nano zinc oxide to prepare functionalized nano zinc oxide. Meanwhile, the application utilizes the silicon-hydrogen addition reaction of polymethylhydrogen siloxane and methyl methacrylate, and then performs ester hydrolysis to prepare carboxylated silicone oil. Then, the functionalized nano zinc oxide and the carboxylated silicone oil are prepared into modified nano zinc oxide through electrostatic self-assembly, so that the carboxylated silicone oil is coated on the surface of the functionalized nano zinc oxide, the impact resistance and water resistance of the film material are improved, the introduced silicone oil is easy to migrate and concentrate on the surface of the polymer material during the combustion process, and a protective silicon-containing carbon layer can be formed at high temperature to give the film material good flame retardant performance. In addition, the chitosan phosphate introduced on the surface of the nano zinc oxide has certain antibacterial and flame retardant effects, and cooperates to give excellent antibacterial and flame retardant performance. Moreover, the modified nano zinc oxide prepared through chemical reaction has good dispersibility in the matrix material, and gives the film material excellent mechanical properties, water resistance, antibacterial performance and flame retardant performance. DETAILED DESCRIPTION

[0016] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the application.

[0017] The preparation method of the modified composite material in Embodiment 1 includes the following steps: I. 6 g of hexagonal boron nitride is ultrasonically dispersed in a tannic acid aqueous solution with a concentration of 0.4 mg / mL, and is treated in an 80℃ oil bath for 2 h, and then is treated in an ice bath for 1 h. Large unexfoliated hexagonal boron nitride is removed by centrifugation at a speed of 2000 rpm, and then is prepared into hexagonal boron nitride nanosheets through centrifugation and drying. II. 24 mL of tetrabutyl titanate and 200 mL of anhydrous ethanol are stirred and mixed, and then 16 mL of acetic acid and 6 g of hexagonal boron nitride nanosheets are added and ultrasonically dispersed for 10 h. After drying treatment, the mixture is calcined in a muffle furnace at a temperature increasing rate of 5℃ / min at 500℃ for 4 h to prepare a titanium dioxide-hexagonal boron nitride nanosheet composite material. III. 6 g of the titanium dioxide-hexagonal boron nitride nanosheet composite material and a sodium hydroxide solution with a concentration of 0.5 mol / L are stirred and mixed, and then are ultrasonically dispersed in 250 mL of N,N-dimethylformamide after washing. 3 mL of epoxy chloropropane is added and stirred for 1 h, and then 12 g of polyhexamethylene biguanide is added and stirred for 1 h. After the reaction, the mixture is prepared into a modified composite material through centrifugation, washing and drying.

[0018] The preparation method of the modified nano zinc oxide in Embodiment 2 includes the following steps: ① Take the volume ratio of 4:1:1 of absolute ethanol, phosphoric acid and triethyl phosphate mixed evenly, then add 5g of phosphorus pentoxide and 6g of chitosan, placed in a 50℃ water bath heating and stirring for 24h, then add excess anhydrous methanol, the precipitate obtained by washing, drying, preparation of chitosan phosphate powder; ② Take 0.7g chitosan phosphate powder dissolved in mass fraction of 2% glacial acetic acid solution, then add 2g of nano zinc oxide, ultrasonic dispersion and stirring for 24h, after reaction by filtration, washing, drying, preparation of functionalized nano zinc oxide; ③ Take 2g functionalized nano zinc oxide ultrasonic dispersion in 100mL deionized water, get the suspension, take 0.2g carboxylated silicone oil added to dilute ammonia water and adjust the pH value to 8, then add to the suspension, stirring for 5min, centrifugal, washing, drying, preparation of modified nano zinc oxide; The preparation method of carboxylated silicone oil includes the following steps: Take 20g polymethylhydrosiloxane, 50mL of toluene and 0.003g of chloroplatinic acid solution (isopropanol solution, concentration of 5g / L) in the reactor, heated to 80℃ under nitrogen atmosphere, slowly drop 30g of methyl acrylate, placed in 140℃ for 28h, then distillation under reduced pressure, centrifugal washing, the product and mass fraction of 10% sodium hydroxide solution is placed in 100℃ for 2h, fractionation of methanol, then the reaction liquid drop into dilute hydrochloric acid solution to adjust the pH value to 6, the precipitate of solid product by washing, drying, preparation of carboxylated silicone oil.

[0019] Example 3 An environmentally friendly antibacterial polyethylene film for packaging, comprising the following components by weight: low density polyethylene 88 parts, modified composite material prepared by example 1 2.2 parts, modified nano zinc oxide prepared by example 2 1.3 parts, lubricant stearyl alcohol ester 0.2 parts.

[0020] The preparation method of the above-mentioned environmentally friendly antibacterial polyethylene film for packaging, comprising the following steps: S1, the components are weighed according to the weight parts, the low density polyethylene, modified composite material, modified nano zinc oxide and lubricant are mechanically blended to obtain the premix; S2, the premix is melt extruded by double screw granulator, water cooled and granulated, the double screw range is set at 150~200℃, to obtain the mixture; S3, the mixture is added to the extrusion casting machine, the screw temperature range is set at 140~190℃, to prepare the environmentally friendly antibacterial polyethylene film for packaging.

[0021] Example 4 An environmentally friendly antibacterial polyethylene film for packaging comprises the following components by weight: low density polyethylene 92 parts, modified composite material prepared in Example 1 4.7 parts, modified nano zinc oxide prepared in Example 2 2.8 parts, lubricant stearyl alcohol ester 0.5 parts.

[0022] The preparation method of the above-mentioned environmentally friendly antibacterial polyethylene film for packaging is the same as that of Example 3.

[0023] Example 5 An environmentally friendly antibacterial polyethylene film for packaging comprises the following components by weight: low density polyethylene 98 parts, modified composite material prepared in Example 1 7.7 parts, modified nano zinc oxide prepared in Example 2 4.7 parts, lubricant stearyl alcohol ester 0.8 parts.

[0024] The preparation method of the above-mentioned environmentally friendly antibacterial polyethylene film for packaging is the same as that of Example 3.

[0025] Comparative Example 1 An environmentally friendly antibacterial polyethylene film for packaging comprises the following components by weight: low density polyethylene 98 parts, titanium dioxide-hexagonal boron nitride nanosheet composite material prepared in Example 1 7.7 parts, modified nano zinc oxide prepared in Example 2 4.7 parts, lubricant stearyl alcohol ester 0.8 parts.

[0026] The preparation method of the above-mentioned environmentally friendly antibacterial polyethylene film for packaging is the same as that of Example 3.

[0027] Comparative Example 2 An environmentally friendly antibacterial polyethylene film for packaging comprises the following components by weight: low density polyethylene 98 parts, hexagonal boron nitride 4.2 parts, nano titanium dioxide 3.5 parts, modified nano zinc oxide prepared in Example 2 4.7 parts, lubricant stearyl alcohol ester 0.8 parts.

[0028] The preparation method of the above-mentioned environmentally friendly antibacterial polyethylene film for packaging is the same as that of Example 3.

[0029] Comparative Example 3 An environmentally friendly antibacterial polyethylene film for packaging comprises the following components by weight: low density polyethylene 98 parts, modified composite material prepared in Example 1 7.7 parts, functionalized nano zinc oxide prepared in Example 2 4.7 parts, lubricant stearyl alcohol ester 0.8 parts.

[0030] The preparation method of the above-mentioned environmentally friendly antibacterial polyethylene film for packaging is the same as that of Example 3.

[0031] Comparative Example 4 An environmentally friendly antibacterial polyethylene film for packaging comprises the following components by weight: low density polyethylene 98 parts, modified composite material prepared in Example 1 7.7 parts, nano zinc oxide 4.7 parts, lubricant stearyl alcohol ester 0.8 parts.

[0032] The preparation method of the above-mentioned environmentally friendly antibacterial polyethylene film for packaging is the same as that of Example 3.

[0033] Performance test The polyethylene films prepared in Examples 3-5 and Comparative Examples 1-4 were subjected to performance test: (1) Mechanical property test: the prepared film was cut into a long strip sample with a width of 15 mm and a length of ≥ 150 mm, the sampling direction was parallel to the film stretching direction (orientation), the stretching speed was set to 200 mm / min, 5 samples were tested and the average value was taken, the tensile strength and elongation at break were tested on a universal material testing machine according to GB / T 1040.3-2006; the sample film was cut into a square sheet with a size of 15 cm x 15 cm, placed in the sample test groove of the puncture resistance tester, the weight puncture strength was adjusted to A level (0.05~6.00N), the weight was released, the sample was punctured, the measurement data was read out, 5 samples were tested and the average value was taken, the puncture resistance test was performed, and the data results are shown in Table 1.

[0034] (2) Water contact angle test: under the same environmental conditions, the water contact angle of the film was detected by a contact angle analyzer to evaluate the water resistance of the sample, and the data results are shown in Table 1.

[0035] (3) Flame retardant property test: the flame retardant property of the sample was evaluated by limiting oxygen index, and the data results are shown in Table 1.

[0036] (4) Antibacterial property test: the antibacterial property was tested according to QB / T 2591-2003, the test bacteria were Staphylococcus aureus and Escherichia coli, and the data results are shown in Table 1.

[0037] Table 1 Performance test results of samples

[0038] From the data results in Table 1, it can be seen that the film samples prepared in Examples 3-5 of the present application have excellent mechanical strength, water resistance, flame retardation and antibacterial properties. Among them, in Comparative Example 1, the modified composite material is replaced by an equal amount of titanium dioxide-hexagonal boron nitride nanosheet composite material, and in Comparative Example 2, hexagonal boron nitride and nanometer titanium dioxide are simply mixed. It is measured that the mechanical properties, E. coli inhibition rate and S. aureus inhibition rate in Comparative Examples 1-2 are lower than those in Examples 3-5, because the grafting of polyhexamethylene biguanide is beneficial to improving the compatibility of the composite material with the matrix and the antibacterial properties. It is measured that the mechanical properties and antibacterial properties in Comparative Example 2 are lower than those in Comparative Example 1, which is more obvious, because the agglomeration phenomenon of hexagonal boron nitride and nanometer titanium dioxide affects the play of mechanical properties and antibacterial properties. In Comparative Example 3, the modified nanometer zinc oxide is replaced by an equal amount of functionalized nanometer zinc oxide, and in Comparative Example 4, the nanometer zinc oxide is not modified. It is measured that the puncture resistance, water contact angle and limiting oxygen index in Comparative Examples 3-4 are lower than those in Examples 3-5, which shows that the coating of carboxylated silicone oil is beneficial to improving the puncture resistance, water resistance and flame retardation of the film material. It is measured that the tensile strength, elongation at break and inhibition rate in Comparative Example 4 are lower than those in Examples 3-5, because the agglomeration phenomenon of nanometer zinc oxide leads to the decrease of mechanical properties, and the introduction of chitosan phosphate further improves the flame retardation and antibacterial properties of the film material to a certain extent.

[0039] In the description of the present specification, the description of the terms "one embodiment", "example", "specific example" and the like means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0040] The basic principles, main features and advantages of the present application are shown and described above. It should be understood by those skilled in the art that the present application is not limited by the above examples, and the above examples and descriptions in the specification are only to illustrate the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed present application.

Claims

1. An environmentally friendly antibacterial polyethylene film for packaging, characterized in that, It comprises the following components by weight: 85-100 parts of low-density polyethylene, 2-8 parts of modified composite material, 1-5 parts of modified nano zinc oxide, and 0.1-1 parts of lubricant; The modified composite material is prepared by exfoliating and functionalizing hexagonal boron nitride with tannic acid, loading titanium dioxide using the sol-gel method, and then grafting polyhexamethylene biguanide onto the prepared titanium dioxide-hexagonal boron nitride nanosheet composite material using a chemical reaction. The modified nano zinc oxide is prepared by loading chitosan phosphate onto the surface of nano zinc oxide through intermolecular dehydration to prepare functionalized nano zinc oxide, and then the functionalized nano zinc oxide and carboxylated silicone oil are prepared by electrostatic self-assembly. The carboxylated silicone oil is prepared by hydrosilylation reaction of polymethylhydrosiloxane and methyl methacrylate followed by ester hydrolysis reaction.

2. The environmentally friendly antibacterial polyethylene film for packaging according to claim 1, characterized in that, The preparation method of the modified composite material includes the following steps: I. Hexagonal boron nitride was ultrasonically dispersed in an aqueous solution of tannic acid and treated in an oil bath at 75-85°C for 2-3 hours. Then, it was ultrasonically treated in an ice bath for 0.5-1 hour. Large, unpeeled hexagonal boron nitride particles were removed by centrifugation. After centrifugation and drying, hexagonal boron nitride nanosheets were prepared. II. Take tetrabutyl titanate and anhydrous ethanol and stir to mix. Then add acetic acid and hexagonal boron nitride nanosheets. Disperse ultrasonically for 8-12 hours. After drying, calcine in a muffle furnace at 450-500℃ for 4-6 hours at a heating rate of 5℃ / min to prepare titanium dioxide-hexagonal boron nitride nanosheet composite material. III. Take titanium dioxide-hexagonal boron nitride nanosheet composite material and sodium hydroxide solution, stir and mix, then take it out, wash it and ultrasonically disperse it in N,N-dimethylformamide, add epichlorohydrin and stir for 0.5~1h, then add polyhexamethylene biguanide and continue stirring for 1~2h. After the reaction is completed, centrifuge, wash and dry to prepare the modified composite material.

3. The environmentally friendly antibacterial polyethylene film for packaging according to claim 2, characterized in that, The mass ratio of the titanium dioxide-hexagonal boron nitride nanosheet composite material to polyhexamethylene biguanide is 1:1~4.

4. The environmentally friendly antibacterial polyethylene film for packaging according to claim 1, characterized in that, The preparation method of the modified nano zinc oxide includes the following steps: ① Mix anhydrous ethanol, phosphoric acid and triethyl phosphate evenly, then add phosphorus pentoxide and chitosan, heat in a water bath at 40~55℃ and stir for 20~24h, then add excess anhydrous methanol, filter and wash and dry the precipitate to prepare chitosan phosphate powder. ② Dissolve chitosan phosphate powder in glacial acetic acid solution, then add nano zinc oxide, ultrasonically disperse evenly and stir for 20-24 hours. After the reaction is completed, filter, wash and dry to prepare functionalized nano zinc oxide. ③ Disperse functionalized nano zinc oxide in deionized water using ultrasound to obtain a suspension. Add carboxylated silicone oil to dilute ammonia and adjust the pH to 8. Then add the carboxylated silicone oil to the suspension and stir for 3-5 minutes. After centrifugation, washing, and drying, modified nano zinc oxide is obtained.

5. The environmentally friendly antibacterial polyethylene film for packaging according to claim 4, characterized in that, In step ①, the volume ratio of anhydrous ethanol, phosphoric acid, and triethyl phosphate is 4:1:1; the mass ratio of phosphorus pentoxide and chitosan is 0.7~0.9:

1.

6. The environmentally friendly antibacterial polyethylene film for packaging according to claim 4, characterized in that, In step ②, the mass ratio of nano zinc oxide to chitosan phosphate powder is 1:0.2~0.

4.

7. The environmentally friendly antibacterial polyethylene film for packaging according to claim 4, characterized in that, In step ③, the mass ratio of functionalized nano zinc oxide to carboxylated silicone oil is 1:0.05~0.

2.

8. The environmentally friendly antibacterial polyethylene film for packaging according to claim 4, characterized in that, The preparation method of the carboxylated silicone oil includes the following steps: Polymethylhydrosiloxane, toluene, and chloroplatinic acid hexahydrate solution were placed in a reactor and heated to 75-85°C under a nitrogen atmosphere. Methyl methacrylate was slowly added dropwise, and the mixture was reacted at 140-145°C for 24-30 hours. The product was then subjected to vacuum distillation and centrifugation. The resulting product and sodium hydroxide solution were hydrolyzed at 95-102°C for 1.5-2 hours. Methanol was fractionally distilled off, and the pH of the reaction mixture was adjusted to 6 by adding dilute hydrochloric acid solution. The precipitated solid product was washed and dried to prepare carboxylated silicone oil.

9. The environmentally friendly antibacterial polyethylene film for packaging according to claim 1, characterized in that, The lubricant is one or a combination of two of stearyl stearate or polyethylene wax.

10. A method for preparing an environmentally friendly antibacterial polyethylene film for packaging according to any one of claims 1 to 9, characterized in that, Includes the following steps: S1. Weigh each component according to the weight parts, and mechanically blend the low-density polyethylene, modified composite material, modified nano zinc oxide and lubricant to obtain a premix; S2. The premixed material is melt-extruded and water-cooled pelletized by a twin-screw granulator. The twin-screw temperature is set at 150~200℃ to obtain the mixture. S3. Add the mixture to the extrusion casting machine, set the screw temperature range to 140~190℃, and prepare an environmentally friendly antibacterial polyethylene film for packaging.

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