Antistatic polyolefin packaging film and method for processing the same

Abstract

This invention discloses an antistatic polyolefin packaging film and its processing method, relating to the field of packaging film technology. The packaging film is produced by loading the prepared antistatic inner layer material, core layer material, and outer layer material into the corresponding extruders of a three-layer co-extrusion blown film machine, plasticizing and extruding to form the antistatic inner layer film, core layer film, and outer layer film respectively, followed by blow-blowing and winding. The antistatic inner layer film is composed of the following parts by weight of raw materials: 50-60 parts linear low-density polyethylene, 20-25 parts metallocene polyethylene, 20-30 parts ethylene-α-olefin copolymer, and 2-5 parts antistatic agent. The antistatic agent is obtained by compounding aluminum-doped zinc oxide powder and polyion-modified attapulgite. The antistatic polyolefin packaging film produced by this invention has good application effects.

Description

Technical Field

[0001] This invention relates to the field of packaging film technology, specifically to an antistatic polyolefin packaging film and its processing method. Background Technology

[0002] In the packaging materials industry, especially in plastic film products, static electricity accumulation is a common and challenging problem. Plastics (such as polyethylene and polypropylene) are widely used due to their excellent insulation and low cost, but their high surface resistivity makes them prone to static electricity generation during production, transportation, and use due to friction, peeling, and other factors. The hazards caused by static electricity accumulation include, but are not limited to, adsorbing contaminants that affect product appearance quality, and safety hazards such as fires and explosions caused by electrostatic discharge. To address these problems, antistatic packaging films have emerged.

[0003] Antistatic packaging films effectively prevent static electricity accumulation by reducing the surface resistivity of materials through the addition of antistatic agents or surface treatment techniques. Currently, the production of antistatic packaging films typically employs the following processes: 1) blending antistatic agents with a substrate to form an antistatic masterbatch, which is then processed into a film; 2) coating the film surface with an antistatic coating to achieve the antistatic effect; 3) irradiating the substrate material with gamma or beta rays to impart antistatic properties to its surface. Although antistatic packaging film technology has made some progress, some shortcomings remain. For example, in process 1) above, the use of antistatic agents blended with the substrate leads to easy migration of the antistatic agent, resulting in a significant decay of antistatic performance over time; the addition of antistatic agents also reduces the mechanical properties of the material. Therefore, there is an urgent need to find an antistatic packaging film to address these problems. Summary of the Invention

[0004] The purpose of this invention is to provide an antistatic polyolefin packaging film and its processing method to solve the problems raised in the prior art.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] An antistatic polyolefin packaging film, characterized in that the antistatic polyolefin packaging film is composed of an antistatic inner layer film, a core layer film and an outer layer film stacked sequentially.

[0007] The antistatic inner layer film is composed of the following parts by weight of raw materials: 50-60 parts linear low-density polyethylene, 20-25 parts metallocene polyethylene, 20-30 parts ethylene-α-olefin copolymer and 2-5 parts antistatic agent.

[0008] The core film is composed of the following parts by weight of raw materials: 50-60 parts linear low-density polyethylene and 40-50 parts low-density polyethylene;

[0009] The outer film is composed of the following parts by weight of raw materials: 50-60 parts linear low-density polyethylene and 40-50 parts low-density polyethylene.

[0010] Preferably, the antistatic agent in the raw materials used in the above-mentioned antistatic inner layer film is a compound combination of aluminum-doped zinc oxide powder and polyion-modified attapulgite, and the mass ratio of aluminum-doped zinc oxide powder to polyion-modified attapulgite is 1:(1-4).

[0011] Preferably, the preparation steps of the polyion-modified attapulgite are as follows:

[0012] Step s1: Take nano-attapulgite, crush and grind it through a 400-mesh sieve, and then perform acid treatment. Place it in hydrochloric acid solution, ultrasonically disperse it for 30 min, then heat it to 60℃ and stir for 6-8 h. After standing overnight, filter and wash it, dry it, and place it in isopropanol. Ultrasonically disperse it for 30 min under a nitrogen atmosphere, then add γ-methacryloyloxypropyltrimethoxysilane. Stir and react at 60-70℃ for 4 h, then centrifuge and wash it with alcohol. After drying, the pretreated attapulgite is obtained.

[0013] Step s2: Mix the pretreated attapulgite prepared in step s1 with methacryloyloxyethyltrimethylammonium chloride, place it in isopropanol, introduce nitrogen gas, heat to 60-70℃ and stir for 1 hour, add azobisisobutyronitrile and continue stirring for 20-24 hours, centrifuge and wash with alcohol, dry and place in deionized water, stir until the system dissolves to obtain solution a, dissolve sodium tetrafluoroborate in warm water to obtain solution b, slowly add it to solution a, stir for 10-12 hours, filter, wash with water, and dry to obtain polyion-modified attapulgite.

[0014] Preferably, the ratio of γ-methacryloxypropyltrimethoxysilane to nano-attapulgite is 1 mL:(0.5-1) g; the mass ratio of pretreated attapulgite to methacryloxyethyltrimethylammonium chloride in step s2 is 1:(2-3); the mass of azobisisobutyronitrile accounts for 0.4-1% of methacryloxyethyltrimethylammonium chloride; and the concentration ratio of solution a to solution b is 1:(0.6-2) g / mL.

[0015] Preferably, the preparation steps of the aluminum-doped zinc oxide powder are as follows: zinc chloride and aluminum nitrate nonahydrate are placed in deionized water, polyethylene glycol is added, and the mixture is stirred for 20-30 minutes. Then, sodium bicarbonate solution is slowly added dropwise while stirring continuously. The mixture is reacted at 40-60°C for 2-3 hours, allowed to stand and age overnight, and then the solid is filtered out. The solid is washed with alcohol and water alternately 2-3 times and then dried at 100-120°C for 12 hours. Finally, the solid is calcined and kept at 800-1000°C for 2-3 hours to obtain aluminum-doped zinc oxide powder. The ratio of zinc chloride, aluminum nitrate nonahydrate and polyethylene glycol is 1:(0.05-0.25):(0.02-0.04).

[0016] Preferably, the processing method of the above-mentioned antistatic polyolefin packaging film is as follows:

[0017] Step 1: Mix linear low-density polyethylene, metallocene polyethylene, and half of the antistatic agent, and melt blend at 180°C to obtain intermediate a, for later use; mix ethylene-α-olefin copolymer and the remaining antistatic agent, and melt blend at 170-200°C to obtain intermediate b, which is then mixed with intermediate a to obtain the antistatic inner layer material; mix linear low-density polyethylene and low-density polyethylene to obtain the core layer material and outer layer material, respectively, for later use.

[0018] Step 2: The antistatic inner layer material, core layer material and outer layer material prepared in Step 1 are respectively loaded into the corresponding extruders of the three-layer co-extrusion blown film machine, and plasticized and extruded at 200-210℃ to form antistatic inner layer film, core layer film and outer layer film respectively. After blowing, they are drawn and wound to obtain packaging film.

[0019] Preferably, the thickness of the packaging film is 120-200μm; wherein the thickness ratio of the antistatic inner film, the core film and the outer film is 1:1:1.

[0020] Compared with the prior art, the beneficial effects of the present invention are:

[0021] 1. This invention uses a three-layer co-extrusion blown film process to obtain a packaging film. The inner layer is made of linear low-density polyethylene, metallocene polyethylene, ethylene-α-olefin copolymer and antistatic agent in a certain ratio to achieve inner layer functionalization. The outer layer and core layer are both made of linear low-density polyethylene and low-density polyethylene compound combination to maintain the overall performance of the packaging film. While achieving high performance of the inner layer, the cost is balanced to meet market demand.

[0022] 2. The inner layer material used in the processing is a mixture of intermediate a obtained by melt blending linear low-density polyethylene, metallocene polyethylene and part of the antistatic agent, and intermediate b obtained by melt blending ethylene-α-olefin copolymer and the remaining antistatic agent. This improves the compatibility of the antistatic agent in the polyolefin film and reduces agglomeration. The antistatic agent is a combination of aluminum-doped zinc oxide powder and polyion-modified attapulgite. Aluminum-doped zinc oxide powder, as a transparent conductive oxide, has good conductivity. The polyion-modified attapulgite is grafted onto silane-pretreated attapulgite using quaternary ammonium salt polyionic liquid, achieving hybridization of polyionic liquid and inorganic carrier, improving the thermal stability of polyionic liquid, and the introduction of attapulgite improves the agglomeration of polyionic liquid. Furthermore, it effectively delays the migration of quaternary ammonium salt polyionic liquid to the matrix surface, achieving long-term antistatic performance. The combination of aluminum-doped zinc oxide powder and polyion-modified attapulgite synergistically improves the antistatic performance.

[0023] 3. Add antistatic agents in a certain proportion to achieve high antistatic performance while ensuring high transparency of the polyolefin packaging film; in addition, aluminum-doped zinc oxide has certain antibacterial properties, expanding the application fields of the produced polyolefin packaging film. Detailed Implementation

[0024] 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.

[0025] In the experiment, linear low-density polyethylene DFDA-7042 and low-density polyethylene 951-000 were purchased from Maoming Petrochemical; metallocene polyethylene 2018.RA was purchased from ExxonMobil; ethylene-α-olefin copolymer POE-DF710 came from Mitsui Chemicals; and attapulgite 400 mesh was purchased from Lingshou Yanguo Mineral Products Processing Plant.

[0026] The preparation steps of aluminum-doped zinc oxide powder are as follows: 4.28 g of zinc chloride and 1.05 g of aluminum nitrate nonahydrate are placed in 100 mL of deionized water, 0.12 g of polyethylene glycol is added, and the mixture is stirred for 30 min. Then, 200 mL of 1 M sodium bicarbonate solution is slowly added dropwise while stirring continuously. The mixture is reacted at 60 °C for 2 h, allowed to stand and age overnight, and then the solid is filtered out. The solid is washed three times with alternating alcohol and water, dried at 100 °C for 12 h, and then calcined at 900 °C for 3 h to obtain aluminum-doped zinc oxide powder.

[0027] Example 1: This example provides a processing method for an antistatic polyolefin packaging film, the specific steps of which are as follows:

[0028] Step 1: Mix 53 parts of linear low-density polyethylene, 23 parts of metallocene polyethylene, and 2 parts of antistatic agent, and melt blend at 180°C to obtain intermediate a, for later use; mix 20 parts of ethylene-α-olefin copolymer and 2 parts of antistatic agent, and melt blend at 200°C to obtain intermediate b, which is then mixed with intermediate a to obtain the antistatic inner layer material; mix 50 parts of linear low-density polyethylene and 50 parts of low-density polyethylene to obtain the core layer material and outer layer material, respectively, for later use.

[0029] Step 2: The antistatic inner layer material, core layer material and outer layer material prepared in Step 1 are loaded into the corresponding extruders of the three-layer co-extrusion blown film machine in a mass ratio of 1:1:1. They are plasticized and extruded at 200°C to form antistatic inner layer film, core layer film and outer layer film respectively. After blowing, they are drawn and wound to obtain a packaging film with a thickness of 200μm.

[0030] The antistatic agent is obtained by mixing aluminum-doped zinc oxide powder and polyion-modified attapulgite in a mass ratio of 1:3.

[0031] The preparation steps of polyion-modified attapulgite are as follows:

[0032] Step s1: Take 5.02g of nano-attapulgite, crush and grind it through a 400-mesh sieve, and then acid treat it. Place it in 50mL of 1mol / L hydrochloric acid solution, ultrasonically disperse it for 30min, then heat it to 60℃ and stir for 6h. After standing overnight, filter and wash it, dry it, and place it in 100mL of isopropanol. Ultrasonically disperse it for 30min under a nitrogen atmosphere, then add 5mL of γ-methacryloyloxypropyltrimethoxysilane. Stir and react at 60℃ for 4h, then centrifuge and wash it with alcohol. After drying, the pretreated attapulgite is obtained.

[0033] Step s2: Take 3.01g of the pretreated attapulgite prepared in step s1 and mix it with 8.48g of methacryloyloxyethyltrimethylammonium chloride. Place it in 100mL of isopropanol, introduce nitrogen gas, heat to 70℃ and stir for 1h. Add 0.08g of azobisisobutyronitrile and continue stirring for 20h. After centrifugation and alcohol washing, dry it and place it in 80mL of deionized water. Stir until the system dissolves to obtain solution a. Place 13.50g of sodium tetrafluoroborate in 100mL of warm water and stir to dissolve to obtain solution b. Slowly add it to solution a and stir for 10h. After filtration, wash with water and dry to obtain polyion-modified attapulgite.

[0034] Example 2: This example provides a processing method for an antistatic polyolefin packaging film, the specific steps of which are as follows:

[0035] Step 1: Mix 50 parts of linear low-density polyethylene, 25 parts of metallocene polyethylene, and 2.5 parts of antistatic agent, and melt blend at 180°C to obtain intermediate a, for later use; mix 20 parts of ethylene-α-olefin copolymer and 2.5 parts of antistatic agent, and melt blend at 200°C to obtain intermediate b, which is then mixed with intermediate a to obtain the antistatic inner layer material; mix 50 parts of linear low-density polyethylene and 50 parts of low-density polyethylene to obtain the core layer material and outer layer material, respectively, for later use.

[0036] Step 2: The antistatic inner layer material, core layer material and outer layer material prepared in Step 1 are loaded into the corresponding extruders of the three-layer co-extrusion blown film machine in a mass ratio of 1:1:1. They are plasticized and extruded at 200°C to form antistatic inner layer film, core layer film and outer layer film respectively. After blowing, they are drawn and wound to obtain a packaging film with a thickness of 200μm.

[0037] The antistatic agent is obtained by mixing aluminum-doped zinc oxide powder and polyion-modified attapulgite in a mass ratio of 1:4.

[0038] The preparation steps of polyion-modified attapulgite are as follows:

[0039] Step s1: Take 5g of nano-attapulgite, crush and grind it through a 400-mesh sieve, and then acid treat it. Place it in 50mL of 1mol / L hydrochloric acid solution, ultrasonically disperse it for 30min, then heat it to 60℃ and stir for 6h. After standing overnight, filter and wash it, dry it, and place it in 100mL of isopropanol. Ultrasonically disperse it for 30min under a nitrogen atmosphere, then add 5mL of γ-methacryloyloxypropyltrimethoxysilane. Stir and react at 70℃ for 4h, then centrifuge and wash it with alcohol. After drying, the pretreated attapulgite is obtained.

[0040] Step s2: Take 3.01g of the pretreated attapulgite prepared in step s1 and mix it with 8.25g of methacryloyloxyethyltrimethylammonium chloride. Place it in 100mL of isopropanol, introduce nitrogen gas, heat to 70℃ and stir for 1h. Add 0.08g of azobisisobutyronitrile and continue stirring for 20h. After centrifugation and alcohol washing, dry it and place it in 80mL of deionized water. Stir until the system dissolves to obtain solution a. Place 13.48g of sodium tetrafluoroborate in 100mL of warm water and stir to dissolve to obtain solution b. Slowly add it to solution a and stir for 12h. After filtration, wash with water and dry to obtain polyion-modified attapulgite.

[0041] Example 3: This example provides a processing method for an antistatic polyolefin packaging film, the specific steps of which are as follows:

[0042] Step 1: Mix 58 parts of linear low-density polyethylene, 20 parts of metallocene polyethylene, and 1 part of antistatic agent, and melt blend at 180°C to obtain intermediate a, for later use; mix 20 parts of ethylene-α-olefin copolymer and 1 part of antistatic agent, and melt blend at 200°C to obtain intermediate b, which is then mixed with intermediate a to obtain the antistatic inner layer material; mix 50 parts of linear low-density polyethylene and 50 parts of low-density polyethylene to obtain the core layer material and outer layer material, respectively, for later use.

[0043] Step 2: The antistatic inner layer material, core layer material and outer layer material prepared in Step 1 are loaded into the corresponding extruders of the three-layer co-extrusion blown film machine in a mass ratio of 1:1:1. They are plasticized and extruded at 200°C to form antistatic inner layer film, core layer film and outer layer film respectively. After blowing, they are drawn and wound to obtain a packaging film with a thickness of 200μm.

[0044] The antistatic agent is obtained by mixing aluminum-doped zinc oxide powder and polyion-modified attapulgite in a mass ratio of 1:2.

[0045] The preparation steps of polyion-modified attapulgite are as follows:

[0046] Step s1: Take 5g of nano-attapulgite, crush and grind it through a 400-mesh sieve, and then acid treat it. Place it in 50mL of 1mol / L hydrochloric acid solution, ultrasonically disperse it for 30min, then heat it to 60℃ and stir for 6h. After standing overnight, filter and wash it, dry it, and place it in 100mL of isopropanol. Ultrasonically disperse it for 30min under a nitrogen atmosphere, then add 5mL of γ-methacryloyloxypropyltrimethoxysilane. Stir and react at 60℃ for 4h, then centrifuge and wash it with alcohol. After drying, the pretreated attapulgite is obtained.

[0047] Step s2: Take 3g of the pretreated attapulgite prepared in step s1 and mix it with 6.49g of methacryloyloxyethyltrimethylammonium chloride. Place it in 100mL of isopropanol, introduce nitrogen gas, heat to 70℃ and stir for 1h. Add 0.08g of azobisisobutyronitrile and continue stirring for 20h. After centrifugation and alcohol washing, dry it and place it in 80mL of deionized water. Stir until the system dissolves to obtain solution a. Place 13.47g of sodium tetrafluoroborate in 100mL of warm water and stir to dissolve to obtain solution b. Slowly add it to solution a and stir for 10h. After filtration, wash with water and dry to obtain polyion-modified attapulgite.

[0048] Comparative Example 1: As a control experiment for Example 1, the composition of the raw materials in the antistatic inner layer was adjusted, while other parameters remained unchanged. The steps are as follows:

[0049] Step 1: Mix 51 parts of linear low-density polyethylene, 23 parts of metallocene polyethylene, and 3 parts of antistatic agent, and melt blend at 180°C to obtain intermediate a, for later use; mix 20 parts of ethylene-α-olefin copolymer and 3 parts of antistatic agent, and melt blend at 200°C to obtain intermediate b, which is then mixed with intermediate a to obtain the antistatic inner layer material; mix 50 parts of linear low-density polyethylene and 50 parts of low-density polyethylene to obtain the core layer material and outer layer material, respectively, for later use.

[0050] Step 2: The antistatic inner layer material, core layer material and outer layer material prepared in Step 1 are loaded into the corresponding extruders of the three-layer co-extrusion blown film machine in a mass ratio of 1:1:1. They are plasticized and extruded at 200°C to form antistatic inner layer film, core layer film and outer layer film respectively. After blowing, they are drawn and wound to obtain a packaging film with a thickness of 200μm.

[0051] The antistatic agent is obtained by mixing aluminum-doped zinc oxide powder and polyion-modified attapulgite in a mass ratio of 1:3.

[0052] The preparation steps of polyion-modified attapulgite are as follows:

[0053] Step s1: Take 5.02g of nano-attapulgite, crush and grind it through a 400-mesh sieve, and then acid treat it. Place it in 50mL of 1mol / L hydrochloric acid solution, ultrasonically disperse it for 30min, then heat it to 60℃ and stir for 6h. After standing overnight, filter and wash it, dry it, and place it in 100mL of isopropanol. Ultrasonically disperse it for 30min under a nitrogen atmosphere, then add 5mL of γ-methacryloyloxypropyltrimethoxysilane. Stir and react at 60℃ for 4h, then centrifuge and wash it with alcohol. After drying, the pretreated attapulgite is obtained.

[0054] Step s2: Take 3.01g of the pretreated attapulgite prepared in step s1 and mix it with 8.48g of methacryloyloxyethyltrimethylammonium chloride. Place it in 100mL of isopropanol, introduce nitrogen gas, heat to 70℃ and stir for 1h. Add 0.08g of azobisisobutyronitrile and continue stirring for 20h. After centrifugation and alcohol washing, dry it and place it in 80mL of deionized water. Stir until the system dissolves to obtain solution a. Place 13.50g of sodium tetrafluoroborate in 100mL of warm water and stir to dissolve to obtain solution b. Slowly add it to solution a and stir for 10h. After filtration, wash with water and dry to obtain polyion-modified attapulgite.

[0055] Comparative Example 2: As a control experiment for Example 1, the antistatic agent was changed to a single polyion-modified attapulgite, while other parameters remained unchanged. The specific steps are as follows:

[0056] Step 1: Mix 53 parts of linear low-density polyethylene, 23 parts of metallocene polyethylene, and 2 parts of polyion-modified attapulgite, and melt blend at 180°C to obtain intermediate a, for later use; mix 20 parts of ethylene-α-olefin copolymer and 2 parts of polyion-modified attapulgite, and melt blend at 200°C to obtain intermediate b, which is then mixed with intermediate a to obtain the antistatic inner layer material; mix 50 parts of linear low-density polyethylene and 50 parts of low-density polyethylene to obtain the core layer material and outer layer material, respectively, for later use.

[0057] Step 2: The antistatic inner layer material, core layer material and outer layer material prepared in Step 1 are loaded into the corresponding extruders of the three-layer co-extrusion blown film machine in a mass ratio of 1:1:1. They are plasticized and extruded at 200°C to form antistatic inner layer film, core layer film and outer layer film respectively. After blowing, they are drawn and wound to obtain a packaging film with a thickness of 200μm.

[0058] The preparation steps of polyion-modified attapulgite are as follows:

[0059] Step s1: Take 5.02g of nano-attapulgite, crush and grind it through a 400-mesh sieve, and then acid treat it. Place it in 50mL of 1mol / L hydrochloric acid solution, ultrasonically disperse it for 30min, then heat it to 60℃ and stir for 6h. After standing overnight, filter and wash it, dry it, and place it in 100mL of isopropanol. Ultrasonically disperse it for 30min under a nitrogen atmosphere, then add 5mL of γ-methacryloyloxypropyltrimethoxysilane. Stir and react at 60℃ for 4h, then centrifuge and wash it with alcohol. After drying, the pretreated attapulgite is obtained.

[0060] Step s2: Take 3.01g of the pretreated attapulgite prepared in step s1 and mix it with 8.48g of methacryloyloxyethyltrimethylammonium chloride. Place it in 100mL of isopropanol, introduce nitrogen gas, heat to 70℃ and stir for 1h. Add 0.08g of azobisisobutyronitrile and continue stirring for 20h. After centrifugation and alcohol washing, dry it and place it in 80mL of deionized water. Stir until the system dissolves to obtain solution a. Place 13.50g of sodium tetrafluoroborate in 100mL of warm water and stir to dissolve to obtain solution b. Slowly add it to solution a and stir for 10h. After filtration, wash with water and dry to obtain polyion-modified attapulgite.

[0061] Comparative Example 3: As a control experiment for Example 1, the antistatic agent was adjusted to be a single aluminum-doped zinc oxide powder. The specific steps are as follows:

[0062] Step 1: Mix 53 parts of linear low-density polyethylene, 23 parts of metallocene polyethylene, and 2 parts of aluminum-doped zinc oxide powder, and melt blend at 180°C to obtain intermediate a, for later use; mix 20 parts of ethylene-α-olefin copolymer and 2 parts of aluminum-doped zinc oxide powder, and melt blend at 200°C to obtain intermediate b, which is then mixed with intermediate a to obtain the antistatic inner layer material; mix 50 parts of linear low-density polyethylene and 50 parts of low-density polyethylene to obtain the core layer material and outer layer material, respectively, for later use.

[0063] Step 2: The antistatic inner layer material, core layer material and outer layer material prepared in Step 1 are loaded into the corresponding extruders of the three-layer co-extrusion blown film machine in a mass ratio of 1:1:1. They are plasticized and extruded at 200°C to form antistatic inner layer film, core layer film and outer layer film respectively. After blowing, they are drawn and wound to obtain a packaging film with a thickness of 200μm.

[0064] Testing and Experiment

[0065] 1. Antistatic properties: The surface resistivity of the inner layer of the packaging film prepared in Examples 1-3 and Comparative Examples 1-3 was measured using a high insulation resistance meter in accordance with GB / T 31838.3, with a test voltage of 500V.

[0066] 2. Optical performance: The transparency and haze of the packaging films prepared in Examples 1-3 and Comparative Examples 1-3 were measured in accordance with GB / T 2410.

[0067] 3. Mechanical properties: The tensile strength and elongation at break of the packaging films prepared in Examples 1-3 and Comparative Examples 1-3 were tested according to GB / T 13022.

[0068]

[0069] Conclusion: The data above shows that the packaging film prepared with the raw material ratio in Example 1 has better overall performance than the other examples. In the three comparative experiments conducted on Example 1, Comparative Example 1 increased the amount of antistatic agent, which slightly improved antistatic performance, but decreased optical and mechanical properties. Comparative Example 2 replaced the antistatic agent with a single component, without adding aluminum-doped zinc oxide (conductive filler), which improved mechanical properties but decreased antistatic and optical properties. Comparative Example 3 did not add polyion-modified attapulgite, resulting in a significant decrease in both antistatic and mechanical properties. Therefore, the combination of aluminum-doped zinc oxide and polyion-modified attapulgite provides better antistatic performance than a single component, and the ratio of each raw material is crucial.

[0070] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. An antistatic polyolefin packaging film, characterized by, The antistatic polyolefin packaging film is composed of an antistatic inner layer film, a core layer film, and an outer layer film stacked sequentially. The antistatic inner layer film is composed of the following parts by weight: 50-60 parts linear low-density polyethylene, 20-25 parts metallocene polyethylene, 20-30 parts ethylene-α-olefin copolymer, and 2-5 parts antistatic agent. The core layer film is composed of the following parts by weight: 50-60 parts linear low-density polyethylene and 40-50 parts low-density polyethylene. The outer layer film is composed of the following parts by weight: 50-60 parts linear low-density polyethylene and 40-50 parts low-density polyethylene. The antistatic agent is a compound of aluminum-doped zinc oxide powder and polyion-modified attapulgite, with a mass ratio of aluminum-doped zinc oxide powder to polyion-modified attapulgite of 1:(1-4). The preparation steps of polyion-modified attapulgite are as follows: Step s1: Take nano-attapulgite, crush and grind it through a 400-mesh sieve, and then perform acid treatment. Place it in hydrochloric acid solution, ultrasonically disperse it for 30 min, then heat it to 60℃ and stir for 6-8 h. After standing overnight, filter and wash it, dry it, and place it in isopropanol. Ultrasonically disperse it for 30 min under a nitrogen atmosphere, then add γ-methacryloyloxypropyltrimethoxysilane. Stir and react at 60-70℃ for 4 h, then centrifuge and wash it with alcohol. After drying, the pretreated attapulgite is obtained. Step s2: Mix the pretreated attapulgite prepared in step s1 with methacryloyloxyethyltrimethylammonium chloride, place it in isopropanol, introduce nitrogen gas, heat to 60-70℃ and stir for 1 hour, add azobisisobutyronitrile and continue stirring for 20-24 hours, centrifuge and wash with alcohol, dry and place in deionized water, stir until the system dissolves to obtain solution a, dissolve sodium tetrafluoroborate in warm water to obtain solution b, slowly add it to solution a, stir for 10-12 hours, filter, wash with water, and dry to obtain polyion-modified attapulgite.

2. The antistatic polyolefin packaging film according to claim 1, characterized in that, The ratio of γ-methacryloxypropyltrimethoxysilane to nano-attapulgite is 1 mL:(0.5-1) g; the mass ratio of pretreated attapulgite to methacryloxyethyltrimethylammonium chloride in step s2 is 1:(2-3); the mass of azobisisobutyronitrile accounts for 0.4-1% of methacryloxyethyltrimethylammonium chloride; the concentration ratio of solution a to solution b is 1:(0.6-2) g / mL.

3. The antistatic polyolefin packaging film according to claim 1, characterized in that, The preparation steps of aluminum-doped zinc oxide powder are as follows: zinc chloride and aluminum nitrate nonahydrate are placed in deionized water, polyethylene glycol is added, and the mixture is stirred for 20-30 minutes. Then, sodium bicarbonate solution is slowly added dropwise while stirring continuously. The mixture is reacted at 40-60℃ for 2-3 hours, allowed to stand and age overnight, and then the solid is filtered out. The solid is washed with alcohol and water alternately 2-3 times and then dried at 100-120℃ for 12 hours. Finally, the solid is calcined and kept at 800-1000℃ for 2-3 hours to obtain aluminum-doped zinc oxide powder.

4. The antistatic polyolefin packaging film according to claim 3, characterized in that, The ratio of zinc chloride, aluminum nitrate nonahydrate, and polyethylene glycol is 1:(0.05-0.25):(0.02-0.04).

5. A method for processing the antistatic polyolefin packaging film according to claim 1, characterized in that, The specific processing method is as follows: Step 1: Mix linear low-density polyethylene, metallocene polyethylene, and half of the antistatic agent, and melt blend at 180°C to obtain intermediate a, for later use; mix ethylene-α-olefin copolymer and the remaining antistatic agent, and melt blend at 170-200°C to obtain intermediate b, which is then mixed with intermediate a to obtain the antistatic inner layer material; mix linear low-density polyethylene and low-density polyethylene to obtain the core layer material and outer layer material, respectively, for later use. Step 2: The antistatic inner layer material, core layer material and outer layer material prepared in Step 1 are respectively loaded into the corresponding extruders of the three-layer co-extrusion blown film machine, and plasticized and extruded at 200-210℃ to form antistatic inner layer film, core layer film and outer layer film respectively. After blowing, they are drawn and wound to obtain packaging film.

6. The processing method according to claim 5, characterized in that, The thickness of the packaging film is 120-200μm; the thickness ratio of the antistatic inner layer film, core layer film and outer layer film is 1:1:1.

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