An antistatic polyethylene composite film and its preparation method

Abstract

The present invention relates to the technical field of polymer membrane materials, and specifically discloses an antistatic polyethylene composite membrane and a preparation method thereof. By mass, it includes the following raw materials: 100 parts of low-density polyethylene, 5-9 parts of high-density polyethylene, 10-20 parts of maleic anhydride grafted polyethylene, 8-15 parts of polyvinyl alcohol modified material, 3-5 parts of antistatic modified carbon black, 0.5-1 part of antioxidant, and 1-2 parts of dispersant. Among them, the polyvinyl alcohol modified material component includes polyvinyl alcohol and carbon nanotubes. The carbon black and the carbon nanotubes are modified to have excellent dispersibility. Through the synergistic effect of physical filling and chemical grafting, the mechanical properties of the polyethylene composite membrane can be effectively enhanced. Acting together with the antistatic agent, a conductive network structure, i.e., a conductive film, can be formed on the surface of the material to prevent the generation and accumulation of static electricity. The raw materials of this polyethylene composite membrane have good compatibility and excellent mechanical and antistatic properties.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer membrane materials, and particularly to an antistatic polyethylene composite membrane and a preparation method thereof. Background Art

[0002] With the continuous progress and innovation of material technology, plastic packaging films have been widely used in fields such as food packaging, electrical protection, and encapsulation of precision electronic components, and can play a role in protecting products. Among them, polyethylene (PE) resin, as a general-purpose plastic, has rich raw material resources, is light in weight, high in strength, and low in cost, has excellent physical and chemical properties, and has a stable and reliable production process. The comprehensive performance of the product is superior and it has a wide range of applications in the packaging field. However, polyethylene has a non-polar molecular structure, is a molecular chain composed of covalent bonds, cannot be ionized, and is difficult to transfer free electrons. Once charged by friction, it is difficult to eliminate. During the daily production and use of polyethylene packaging films, due to friction on the surface, static electricity will accumulate. The accumulation of a large amount of static electricity causes dust to be adsorbed on the surface of the packaging film, affecting its appearance. Static electricity discharge may damage sensitive electronic components, affecting the performance of electronic devices. Static electricity sparks may also ignite flammable substances around, causing fires and posing safety hazards.

[0003] To solve this problem, researchers have developed a variety of antistatic polyethylene films. Chinese Patent Application CN105216349A discloses a preparation method of an antistatic polyethylene film. Surface-modified nano-conductive carbon black is prepared by a ball mill, and it is pre-mixed with linear low-density polyethylene by a ball mill and then co-extruded and granulated with linear low-density polyethylene and metallocene polyethylene. The granulated material is added to a blow molding machine to blow into a film to make an antistatic polyethylene film. This polyethylene film has good antistatic properties by adding conductive fillers, but the dispersion of conductive carbon black is poor, affecting the mechanical properties of the polyethylene film. At the same time, the introduction of metallocene polyethylene in the granulated material has compatibility problems, and phase separation is likely to occur during blending, affecting the performance of the polyethylene film. Chinese Patent Application CN106084432A discloses an antistatic PE film and a preparation method thereof. The antistatic PE film includes a surface layer film, a middle layer film, and a bottom layer film from top to bottom. LDPE polyethylene particles and LLDPE polyethylene particles with a content ratio of 1:3, an antistatic agent accounting for 3-5% of the total amount of the middle layer film material, and a softener accounting for 1-2% of the total amount of the middle layer film material are mixed and stirred evenly and then an antistatic PE film is prepared by three-layer co-extrusion. This PE film has good flexibility and good mechanical properties. However, this PE film is prone to the problem of migration failure of the antistatic agent during long-term use, resulting in insufficient durability of the antistatic property. With the design of a three-layer film, the antistatic agent is not added to the surface layer film and the bottom layer film, resulting in poor antistatic properties.

[0004] Therefore, there is an urgent need to provide a polyethylene film with excellent mechanical properties and stable antistatic properties. Summary of the Invention

[0005] (I) Technical Problem to be Solved

[0006] In view of the deficiencies of the prior art, the present invention provides an antistatic polyethylene composite film and a preparation method thereof, solving the problems of poor antistatic performance and general mechanical properties of the polyethylene composite film.

[0007] (II) Technical Solution

[0008] To achieve the above object, the present invention discloses an antistatic polyethylene composite film, which comprises the following raw materials by mass: 100 parts of low-density polyethylene, 5-9 parts of high-density polyethylene, 10-20 parts of maleic anhydride grafted polyethylene, 8-15 parts of polyvinyl alcohol modified material, 3-5 parts of antistatic modified carbon black, 0.5-1 part of antioxidant, and 1-2 parts of dispersant.

[0009] The preparation method of the antistatic modified carbon black comprises the following steps:

[0010] S1. Mix oxidized carbon black, phosphoric acid, and 3-dimethylamino-1-propylamine evenly, heat up, stir and mix, and react. After the reaction is completed, adjust the pH to neutral with sodium hydroxide solution, carry out vacuum distillation, wash with deionized water and absolute ethanol, and dry in vacuum at 60°C for 24 h to obtain modified carbon black;

[0011] S2. Disperse the modified carbon black in isopropanol, mix evenly, add long-chain haloalkane, heat under reflux, and react. After the reaction is completed, carry out vacuum distillation, wash with acetone, and dry in vacuum at 60°C for 12 h to obtain antistatic modified carbon black.

[0012] The components of the polyvinyl alcohol modified material include polyvinyl alcohol and carbon nanotubes.

[0013] Preferably, in S1, the mass ratio of oxidized carbon black, phosphoric acid, and 3-dimethylamino-1-propylamine is 100:700-900:120-150.

[0014] Preferably, in S1, the reaction temperature is 145-155°C and the reaction time is 10-12 h.

[0015] Preferably, the concentration of the sodium hydroxide solution in S1 is 0.05 mol / L.

[0016] Preferably, the preparation method of the oxidized carbon black in S1 is as follows: Mix carbon black and nitric acid solution with a mass ratio of 100:3000, where the concentration of the nitric acid solution is 4 mol / L, heat up to 90°C, stir, and react for 12 h. After the reaction is completed, carry out suction filtration, wash with deionized water and absolute ethanol, and dry in a vacuum drying oven at 60°C for 12 h to obtain oxidized carbon black.

[0017] Preferably, in S2, the mass ratio of the modified carbon black, isopropanol, and long-chain haloalkane is 100:4500 - 5500:280 - 350, the reaction temperature is 80 - 90 °C, and the reaction time is 24 - 36 h.

[0018] Preferably, the long-chain haloalkane in S2 is a bromoalkane or chloroalkane with 12 - 16 carbon atoms.

[0019] Furthermore, the long-chain haloalkane in S2 preferably includes any one of dodecyl bromide, tetradecyl bromide, hexadecyl bromide, dodecyl chloride, tetradecyl chloride, and hexadecyl chloride.

[0020] Preferably, the preparation method of the polyvinyl alcohol modifier includes the following steps:

[0021] Step 1: Ultrasonically disperse carbon nanotubes in absolute ethanol. After uniform dispersion, add γ-methacryloxypropyltrimethoxysilane, stir and mix, heat to carry out the reaction. After the reaction is completed, carry out suction filtration, wash with absolute ethanol, and dry in vacuum at 60 °C for 12 h to obtain vinyl-functionalized carbon nanotubes;

[0022] Step 2: Mix polyvinyl alcohol and deionized water, add an initiator, vinyl-functionalized carbon nanotubes, and trimethylallyl ammonium chloride, stir and mix to carry out the reaction. After the reaction is completed, adjust the pH to 6 with hydrochloric acid, carry out suction filtration, wash with acetone and deionized water, and dry in an oven at 60 °C for 12 h to obtain the polyvinyl alcohol modifier.

[0023] Preferably, in Step 1, the mass ratio of absolute ethanol, carbon nanotubes, and γ-methacryloxypropyltrimethoxysilane is 6000 - 6500:100:20 - 30.

[0024] Preferably, in Step 1, the reaction temperature is 65 - 75 °C, and the reaction time is 4 - 6 h.

[0025] ‌Preferably, in Step 2, the mass ratio of polyvinyl alcohol, deionized water, initiator, vinyl-functionalized carbon nanotubes, and trimethylallyl ammonium chloride is 100:1200 - 1800:0.03 - 0.1:4 - 9:5 - 10.

[0026] Preferably, in Step 2, the reaction temperature is 55 - 65 °C, and the reaction time is 4 - 6 h.

[0027] Preferably, the initiator in Step 2 is ammonium cerium(IV) sulfate.

[0028] A preparation method of the antistatic polyethylene composite film described above includes the following steps:

[0029] Low-density polyethylene, high-density polyethylene, maleic anhydride grafted polyethylene, polyvinyl alcohol modified material, antistatic modified carbon black, antioxidant, and dispersant were vacuum dried at 80 °C for 2 h. After drying, they were mixed evenly, melt blended in a twin-screw extruder, extruded into pellets, and then subjected to blown film treatment to obtain an antistatic polyethylene composite film.

[0030] Preferably, the processing technology of the twin-screw extruder includes: the heating temperatures of the first to sixth zones of the twin-screw extruder are 160 - 180 °C, 185 - 205 °C, 210 - 230 °C, 230 - 240 °C, 220 - 230 °C, and 200 - 210 °C respectively, the rotation speed is 200 - 300 r / min. During the blown film treatment, the die head temperature is 190 - 200 °C, and the blow-up ratio is 2.5 - 3.0.

[0031] Preferably, the antioxidant is composed of antioxidant 1010 and antioxidant 168 with a mass ratio of 3:2; the dispersant is polyethylene wax.

[0032] (III) Beneficial technical effects

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0034] (1) The carbon black used in the present invention can be used as a filler to improve the strength and hardness of the matrix, has excellent electrical conductivity, forms a conductive path in the matrix, has excellent antistatic properties, and inhibits static electricity accumulation. The carbon black is oxidized and modified to introduce carboxyl groups on the surface of the carbon black to obtain oxidized carbon black. The carboxyl groups on the oxidized carbon black react with the amino groups on 3-dimethylamino-1-propylamine to introduce amide bonds to obtain modified carbon black. The modified carbon black undergoes a quaternization reaction with long-chain haloalkanes to introduce quaternary ammonium salts on the surface of the carbon black, reducing the surface polarity to obtain antistatic modified carbon black. The long-chain alkyl groups introduced on the carbon black can effectively reduce the agglomeration of the carbon black, can be evenly dispersed in the polyethylene matrix, effectively avoid the mechanical defects caused by agglomeration, can effectively maintain the uniformity and ductility of the film. At the same time, the introduced amide bonds and quaternary ammonium salts act together to construct an ionic conductive path, reduce the surface resistivity, inhibit static electricity accumulation, and improve the antistatic persistence of the polyethylene composite film. The antistatic modified carbon black can form a stable conductive network in the polyethylene matrix, avoiding the performance attenuation caused by the migration of traditional antistatic agents.

[0035] (2) In the present invention, γ-methacryloxypropyltrimethoxysilane is used to modify carbon nanotubes to obtain vinyl-functionalized carbon nanotubes. Ammonium cerium sulfate is used as an initiator. Ammonium cerium sulfate decomposes to generate free radicals, which initiate the graft polymerization of polyvinyl alcohol, vinyl-functionalized carbon nanotubes, and trimethylallyl ammonium chloride to obtain a polyvinyl alcohol modified material. Carbon nanotubes have a high aspect ratio and a rigid skeleton structure, and can form a three-dimensional network in the polyethylene matrix, significantly improving the mechanical properties of the composite film. By surface-modifying carbon nanotubes and grafting them onto polyvinyl alcohol, the interfacial bonding force with the polyethylene matrix is enhanced, the stress concentration points are reduced, and the crack propagation is effectively avoided. Furthermore, a rigid support is formed to inhibit the slippage of polyethylene segments and enhance the creep resistance of the material. At the same time, carbon nanotubes have excellent electrical conductivity and can effectively inhibit electrostatic accumulation. Polyvinyl alcohol has excellent film-forming properties, tensile strength, and toughness, and good barrier properties. Adding it to the polyethylene matrix can significantly improve the tensile strength and barrier properties of the composite film, while effectively inhibiting the slippage of polyethylene molecules and improving the creep resistance and durability of the matrix. The polyvinyl alcohol-carbon nanotube-quaternary ammonium salt three-dimensional network formed in the polyvinyl alcohol modified material can improve the electrical conductivity of carbon nanotubes and the antistatic property of the quaternary ammonium salt. The anhydride groups in maleic anhydride-grafted polyethylene form hydrogen bonds with the hydroxyl groups of the polyvinyl alcohol modified material, and can also produce interfacial interactions with the polar groups on the surface of carbon black, improving the compatibility between the raw materials and the toughness of the polyethylene film. The quaternary ammonium salt introduced into the polyethylene composite film can release free ions through ionization to construct an ion conductive pathway. The quaternary ammonium salt is fixed on the matrix by covalent bonds, effectively avoiding migration and loss, and having persistent antistatic properties. The modified carbon black and the polyvinyl alcohol modified material act synergistically to construct a dual-path conductive network to achieve rapid dissipation of static charges.

[0036] (3) The preparation method of the polyethylene composite film in the present invention is simple. Low-density polyethylene has good toughness and excellent film-forming properties, and high-density polyethylene has excellent strength and rigidity. When the two are blended and act synergistically, the mechanical properties can be effectively balanced, and the mechanical properties of the prepared polyethylene composite film are improved. Carbon black and carbon nanotubes act synergistically through physical filling and chemical grafting, which can effectively enhance the mechanical properties of the polyethylene composite film and at the same time effectively inhibit electrostatic accumulation. Acting together with the quaternary ammonium salt, a conductive network structure, i.e., a conductive film, is formed on the surface of the material to prevent the generation and accumulation of static electricity, further improving the antistatic ability of the matrix. The antistatic agent is not easily migrated, and the antistatic property is persistent. Detailed implementation mode

[0037] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention. Example 1

[0038] A preparation method of an antistatic polyethylene composite film includes the following steps:

[0039] By mass, weigh 100 parts of low-density polyethylene, 5 parts of high-density polyethylene, 10 parts of maleic anhydride grafted polyethylene, 8 parts of polyvinyl alcohol modified material, 3 parts of antistatic modified carbon black, 0.5 part of antioxidant, and 1 part of dispersant polyethylene wax. The antioxidant is composed of antioxidant 1010 and antioxidant 168 with a mass ratio of 3:2. Vacuum dry at 80°C for 2h. After drying, mix evenly and melt-blend in a twin-screw extruder. The heating temperatures of the first to sixth zones of the twin-screw extruder are 160°C, 185°C, 210°C, 230°C, 220°C, and 200°C respectively, the rotation speed is 200r / min, extrude and pelletize, and then perform blown film treatment. During the blown film treatment, the die head temperature is 190°C and the blow-up ratio is 2.5 to obtain the antistatic polyethylene composite film.

[0040] The preparation method of the antistatic modified carbon black includes the following steps:

[0041] S1. Mix oxidized carbon black, phosphoric acid, and 3-dimethylamino-1-propylamine with a mass ratio of 100:700:120 evenly, heat up, stir and mix, and react. The reaction temperature is 145°C and the reaction time is 12h. After the reaction, use sodium hydroxide solution to adjust the pH to neutral. The concentration of the sodium hydroxide solution is 0.05mol / L. Perform vacuum distillation, wash with deionized water and absolute ethanol, and vacuum dry at 60°C for 24h to obtain modified carbon black;

[0042] S2. Disperse the modified carbon black in isopropanol, mix evenly, and then add long-chain haloalkane chlorohexadecane. The mass ratio of the modified carbon black, isopropanol, and chlorohexadecane is 100:4500:280. Heat under reflux and react. The reaction temperature is 80°C and the reaction time is 24h. After the reaction, perform vacuum distillation, wash with acetone, and vacuum dry at 60°C for 12h to obtain the antistatic modified carbon black.

[0043] The preparation method of the polyvinyl alcohol modified material includes the following steps:

[0044] Step 1: Ultrasonically disperse carbon nanotubes in absolute ethanol. After uniform dispersion, add γ-methacryloxypropyltrimethoxysilane. The mass ratio of absolute ethanol, carbon nanotubes, and γ-methacryloxypropyltrimethoxysilane is 6000:100:20. Stir and mix, heat, and react. The reaction temperature is 65°C and the reaction time is 6 h. After the reaction, perform suction filtration, wash with absolute ethanol, and vacuum dry at 60°C for 12 h to obtain vinyl-functionalized carbon nanotubes.

[0045] Step 2: Stir and mix polyvinyl alcohol, deionized water, initiator ammonium cerium(IV) sulfate, vinyl-functionalized carbon nanotubes, and trimethylallylammonium chloride with a mass ratio of 100:1200:0.03:4:5, and react. The reaction temperature is 55°C and the reaction time is 6 h. After the reaction, adjust the pH to 6 with hydrochloric acid, perform suction filtration, wash with acetone and deionized water, and dry in an oven at 60°C for 12 h to obtain polyvinyl alcohol modified material. Example 2

[0046] A method for preparing an antistatic polyethylene composite film includes the following steps:

[0047] Weigh 100 parts of low-density polyethylene, 7 parts of high-density polyethylene, 14 parts of maleic anhydride grafted polyethylene, 10 parts of polyvinyl alcohol modified material, 3.5 parts of antistatic modified carbon black, 0.6 part of antioxidant, and 1.5 parts of dispersant polyethylene wax by mass. The antioxidant consists of antioxidant 1010 and antioxidant 168 with a mass ratio of 3:2. Vacuum dry at 80°C for 2 h. After drying, mix evenly and melt-blend in a twin-screw extruder. The heating temperatures of the first to sixth zones of the twin-screw extruder are 170°C, 195°C, 220°C, 235°C, 225°C, and 205°C respectively, and the rotation speed is 240 r / min. Extrude and pelletize, and then perform blown film processing. During the blown film processing, the die head temperature is 195°C and the blow-up ratio is 2.8 to obtain the antistatic polyethylene composite film.

[0048] The preparation method of the antistatic modified carbon black includes the following steps:

[0049] S1: Mix oxidized carbon black, phosphoric acid, and 3-dimethylamino-1-propylamine with a mass ratio of 100:800:130 evenly, raise the temperature, stir and mix, and react. The reaction temperature is 150°C and the reaction time is 11 h. After the reaction, adjust the pH to neutral with sodium hydroxide solution. The concentration of the sodium hydroxide solution is 0.05 mol / L. Perform vacuum distillation, wash with deionized water and absolute ethanol, and vacuum dry at 60°C for 24 h to obtain modified carbon black.

[0050] S2. Disperse the modified carbon black into isopropyl alcohol. After mixing evenly, add long-chain halogenated alkane cetyl chloride. The mass ratio of the modified carbon black, isopropyl alcohol, and cetyl chloride is 100:5000:300. Heat under reflux to carry out the reaction. After the reaction is completed, carry out vacuum distillation, wash with acetone, and dry in vacuum at 60 °C for 12 h to obtain antistatic modified carbon black.

[0051] The preparation method of the polyvinyl alcohol modified material includes the following steps:

[0052] Step 1. Ultrasonically disperse carbon nanotubes into absolute ethanol. After dispersing evenly, add γ-methacryloxypropyltrimethoxysilane. The mass ratio of absolute ethanol, carbon nanotubes, and γ-methacryloxypropyltrimethoxysilane is 6200:100:24. Stir and mix, heat to carry out the reaction. The reaction temperature is 70 °C, and the reaction time is 5 h. After the reaction is completed, carry out suction filtration, wash with absolute ethanol, and dry in vacuum at 60 °C for 12 h to obtain vinyl-functionalized carbon nanotubes.

[0053] Step 2. Stir and mix polyvinyl alcohol, deionized water, initiator ammonium cerium(IV) sulfate, vinyl-functionalized carbon nanotubes, and trimethylallylammonium chloride with a mass ratio of 100:1500:0.05:7:6 to carry out the reaction. The reaction temperature is 60 °C, and the reaction time is 5 h. After the reaction is completed, adjust the pH to 6 with hydrochloric acid, carry out suction filtration, wash with acetone and deionized water, and dry in an oven at 60 °C for 12 h to obtain the polyvinyl alcohol modified material. Example 3

[0054] A preparation method of an antistatic polyethylene composite film includes the following steps:

[0055] By mass, weigh 100 parts of low-density polyethylene, 7 parts of high-density polyethylene, 14 parts of maleic anhydride grafted polyethylene, 10 parts of polyvinyl alcohol modified material, 3.5 parts of antistatic modified carbon black, 0.6 part of antioxidant, and 1.5 parts of dispersant polyethylene wax. The antioxidant is composed of antioxidant 1010 and antioxidant 168 with a mass ratio of 3:2. Dry in vacuum at 80 °C for 2 h. After drying, mix evenly, melt and blend in a twin-screw extruder. The heating temperatures of the first to sixth zones of the twin-screw extruder are 170 °C, 195 °C, 220 °C, 235 °C, 225 °C, and 205 °C respectively, and the rotation speed is 240 r / min. Extrude and pelletize, and then carry out blown film treatment. During the blown film treatment, the die head temperature is 195 °C, and the blow-up ratio is 2.8 to obtain the antistatic polyethylene composite film.

[0056] The preparation method of the antistatic modified carbon black includes the following steps:

[0057] S1. Mix carbon black oxide, phosphoric acid, and 3-dimethylamino-1-propanamine with a mass ratio of 100:800:140 evenly, heat up, stir and mix to make a reaction occur. The reaction temperature is 150 °C and the reaction time is 11 h. After the reaction, adjust the pH to neutral with sodium hydroxide solution with a concentration of 0.05 mol / L, perform vacuum distillation, wash with deionized water and absolute ethanol, and dry in vacuum at 60 °C for 24 h to obtain modified carbon black;

[0058] S2. Disperse the modified carbon black in isopropanol, and after mixing evenly, add long-chain halogenated alkane cetyl chloride. The mass ratio of the modified carbon black, isopropanol, and cetyl chloride is 100:5000:320. Heat under reflux to make a reaction occur. After the reaction, perform vacuum distillation, wash with acetone, and dry in vacuum at 60 °C for 12 h to obtain antistatic modified carbon black.

[0059] The preparation method of the polyvinyl alcohol modified material includes the following steps:

[0060] Step 1. Ultrasonically disperse carbon nanotubes in absolute ethanol. After dispersing evenly, add γ-methacryloxypropyltrimethoxysilane. The mass ratio of absolute ethanol, carbon nanotubes, and γ-methacryloxypropyltrimethoxysilane is 6200:100:28. Stir and mix, heat to make a reaction occur. The reaction temperature is 70 °C and the reaction time is 5 h. After the reaction, perform suction filtration, wash with absolute ethanol, and dry in vacuum at 60 °C for 12 h to obtain vinylated carbon nanotubes;

[0061] Step 2. Stir and mix polyvinyl alcohol, deionized water, initiator ammonium cerium(IV) sulfate, vinylated carbon nanotubes, and trimethylallylammonium chloride with a mass ratio of 100:1500:0.08:8:8 to make a reaction occur. The reaction temperature is 60 °C and the reaction time is 5 h. After the reaction, adjust the pH to 6 with hydrochloric acid, perform suction filtration, wash with acetone and deionized water, and dry in an oven at 60 °C for 12 h to obtain the polyvinyl alcohol modified material. Example 4

[0062] A preparation method of an antistatic polyethylene composite film includes the following steps:

[0063] By mass parts, weigh 100 parts of low-density polyethylene, 8 parts of high-density polyethylene, 18 parts of maleic anhydride grafted polyethylene, 14 parts of polyvinyl alcohol modified material, 4.5 parts of antistatic modified carbon black, 0.8 part of antioxidant, and 1.8 parts of dispersant polyethylene wax. The antioxidant consists of antioxidant 1010 and antioxidant 168 with a mass ratio of 3:2. Dry in vacuum at 80°C for 2 h. After drying, mix evenly and melt-blend in a twin-screw extruder. The heating temperatures of the first to sixth zones of the twin-screw extruder are 175°C, 200°C, 225°C, 235°C, 225°C, and 205°C respectively, the rotation speed is 260 r / min, extrude and pelletize, and then perform blown film treatment. During the blown film treatment, the die head temperature is 195°C and the blow-up ratio is 2.8 to obtain an antistatic polyethylene composite film.

[0064] The preparation methods of the antistatic modified carbon black and the polyvinyl alcohol modified material are the same as those of the antistatic modified carbon black and the polyvinyl alcohol modified material in Example 3. Example 5

[0065] A preparation method of an antistatic polyethylene composite film includes the following steps:

[0066] By mass parts, weigh 100 parts of low-density polyethylene, 9 parts of high-density polyethylene, 20 parts of maleic anhydride grafted polyethylene, 15 parts of polyvinyl alcohol modified material, 5 parts of antistatic modified carbon black, 1 part of antioxidant, and 2 parts of dispersant polyethylene wax. The antioxidant consists of antioxidant 1010 and antioxidant 168 with a mass ratio of 3:2. Dry in vacuum at 80°C for 2 h. After drying, mix evenly and melt-blend in a twin-screw extruder. The heating temperatures of the first to sixth zones of the twin-screw extruder are 180°C, 205°C, 230°C, 240°C, 230°C, and 210°C respectively, the rotation speed is 300 r / min, extrude and pelletize, and then perform blown film treatment. During the blown film treatment, the die head temperature is 200°C and the blow-up ratio is 3.0 to obtain an antistatic polyethylene composite film.

[0067] The preparation method of the antistatic modified carbon black includes the following steps:

[0068] S1. Mix evenly carbon black oxide, phosphoric acid, and 3-dimethylamino-1-propylamine with a mass ratio of 100:900:150, raise the temperature, stir and mix, and react. The reaction temperature is 155°C and the reaction time is 12 h. After the reaction, use sodium hydroxide solution to adjust the pH to neutral. The concentration of the sodium hydroxide solution is 0.05 mol / L. Perform vacuum distillation, wash with deionized water and absolute ethanol, and dry in vacuum at 60°C for 24 h to obtain modified carbon black;

[0069] S2. Disperse the modified carbon black into isopropyl alcohol. After mixing evenly, add long-chain halogenated alkane cetyl chloride. The mass ratio of the modified carbon black, isopropyl alcohol, and cetyl chloride is 100:5500:350. Heat under reflux to carry out the reaction. After the reaction ends, carry out vacuum distillation, wash with acetone, and dry in vacuum at 60 °C for 12 h to obtain antistatic modified carbon black.

[0070] The preparation method of the polyvinyl alcohol modified material includes the following steps:

[0071] Step 1. Ultrasonically disperse carbon nanotubes into absolute ethanol. After dispersing evenly, add γ-methacryloxypropyltrimethoxysilane. The mass ratio of absolute ethanol, carbon nanotubes, and γ-methacryloxypropyltrimethoxysilane is 6500:100:30. Stir and mix, heat to carry out the reaction. The reaction temperature is 75 °C, and the reaction time is 6 h. After the reaction ends, carry out suction filtration, wash with absolute ethanol, and dry in vacuum at 60 °C for 12 h to obtain vinyl-functionalized carbon nanotubes.

[0072] Step 2. Stir and mix polyvinyl alcohol, deionized water, initiator ammonium cerium(IV) sulfate, vinyl-functionalized carbon nanotubes, and trimethylallyl ammonium chloride with a mass ratio of 100:1800:0.1:9:10 to carry out the reaction. The reaction temperature is 65 °C, and the reaction time is 6 h. After the reaction ends, adjust the pH to 6 with hydrochloric acid, carry out suction filtration, wash with acetone and deionized water, and dry in a drying oven at 60 °C for 12 h to obtain the polyvinyl alcohol modified material. Comparative Example 1

[0073] A preparation method of a polyethylene composite film includes the following steps:

[0074] By mass, weigh 100 parts of low-density polyethylene, 8 parts of high-density polyethylene, 18 parts of maleic anhydride grafted polyethylene, 14 parts of polyvinyl alcohol modified material, 4.5 parts of oxidized carbon black, 0.8 part of antioxidant, and 1.8 parts of dispersant polyethylene wax. The antioxidant is composed of antioxidant 1010 and antioxidant 168 with a mass ratio of 3:2. Dry in vacuum at 80 °C for 2 h. After drying, mix evenly, carry out melt blending in a twin-screw extruder. The heating temperatures of the first to sixth zones of the twin-screw extruder are 175 °C, 200 °C, 225 °C, 235 °C, 225 °C, and 205 °C respectively, the rotation speed is 260 r / min, extrude and pelletize, and then carry out blown film treatment. During the blown film treatment, the die head temperature is 195 °C, and the blow-up ratio is 2.8 to obtain the polyethylene composite film.

[0075] The preparation method of the polyvinyl alcohol modified material is the same as that of the polyvinyl alcohol modified material in Example 3. Comparative Example 2

[0076] A preparation method of a polyethylene composite film includes the following steps:

[0077] By weight, 100 parts of low-density polyethylene, 8 parts of high-density polyethylene, 18 parts of maleic anhydride grafted polyethylene, 13 parts of polyvinyl alcohol, 1 part of carbon nanotubes, 4.5 parts of antistatic modified carbon black, 0.8 part of antioxidant, and 1.8 parts of dispersant polyethylene wax are weighed. The antioxidant is composed of antioxidant 1010 and antioxidant 168 with a mass ratio of 3:2. It is vacuum dried at 80 °C for 2 h. After drying, it is mixed evenly and melt-blended in a twin-screw extruder. The heating temperatures of the first to sixth zones of the twin-screw extruder are 175 °C, 200 °C, 225 °C, 235 °C, 225 °C, and 205 °C respectively, the rotation speed is 260 r / min, and then it is extruded and pelletized. Then, it is subjected to blown film treatment. During the blown film treatment, the die head temperature is 195 °C and the blow-up ratio is 2.8, obtaining a polyethylene composite film.

[0078] The preparation method of the antistatic modified carbon black is the same as that of the antistatic modified carbon black in Example 3.

[0079] The preparation method of the oxidized carbon black in the examples and comparative examples of the present invention is as follows: Carbon black and nitric acid solution with a mass ratio of 100:3000 are mixed, where the concentration of the nitric acid solution is 4 mol / L. It is heated to 90 °C, stirred, and reacted for 12 h. After the reaction, it is filtered by suction, washed with deionized water and absolute ethanol, and dried in a vacuum drying oven at 60 °C for 12 h to obtain oxidized carbon black.

[0080] The carbon black used in the examples and comparative examples of the present invention is purchased from Qingdao Degussa Chemical Co., Ltd., with the model of carbon black N330; the carbon nanotubes are purchased from Beijing DeKeDaoJin Technology Co., Ltd., with the model of CNT204 carbon nanotubes; the low-density polyethylene is purchased from Maoming Petrochemical Co., Ltd., China National Petroleum Corporation, with the model of 2426H, the melt index is 1.9 g / 10 min, and the density is 0.9 g / cm 3 ; the high-density polyethylene is purchased from Dongguan Shunyu Chemical Co., Ltd., with the brand of LH606; the maleic anhydride grafted polyethylene is purchased from Dongguan Shangyi Plastics Co., Ltd., with the brand of NF358E; the polyvinyl alcohol is purchased from Tianjin Alfa Aesar Co., Ltd., with a number average molecular weight of 60000; other unrevealed reagents are all commercially available.

[0081] The polyethylene composite films prepared in Examples 1-5 and Comparative Examples 1-2 are subjected to relevant performance tests as follows:

[0082] (1) Antistatic performance test: The antistatic performance of the polyethylene composite films prepared in Examples 1-5 and Comparative Examples 1-2 is tested. The test method refers to GB / T 1410-2006 "Test Methods for Volume Resistivity and Surface Resistivity of Solid Insulating Materials", and the surface resistance of the composite film is recorded;

[0083] (2)Mechanical property test: The tensile properties of the polyethylene composite films prepared in Examples 1-5 and Comparative Examples 1-2 were tested. The test method referred to GB / T 1040.3-2006 Plastics - Determination of tensile properties - Part 3: Test conditions for films and sheets. Each group of samples was tested three times, and the tensile strength and elongation at break of the composite film were recorded. According to the ASTM F1306 test standard, the puncture resistance of the samples was tested. The diameter of the puncture needle used was 1 mm, and the puncture speed was 50 mm / min. Each group of samples was tested three times, and the maximum force value was recorded;

[0084] The above test results are shown in Table 1 as follows:

[0085] Table 1

[0086]

[0087] It can be seen from the test results in Table 1 that the polyethylene composite films prepared in Examples 1-5 have excellent mechanical properties and antistatic properties. Adding fillers and polyvinyl alcohol can effectively improve the local bearing capacity of the matrix. At the same time, there is excellent interfacial bonding force between the raw materials, the material properties are stable, and it has a high puncture resistance and a high puncture resistance strength. In Comparative Example 1, the oxidized carbon black was not modified, the dispersibility of the carbon black was poor, and the mechanical properties became worse. Moreover, amide bonds and quaternary ammonium salts were not introduced on the surface of the carbon black, so the antistatic property became worse. The corresponding surface resistivity was 2.5×10 11 Ω / sq, the tensile strength was 21.3 MPa, the elongation at break was 305%, and the puncture resistance strength was 57.3 N. In Comparative Example 2, the carbon nanotubes were not modified, the dispersibility became worse, and they were prone to agglomeration. The corresponding surface resistivity of the sample was 8.4×10 10 Ω / sq, the tensile strength was 23.7 MPa, the elongation at break was 324%, and the puncture resistance strength was 60.5 N.

[0088] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made therein without departing from the principles and spirit of the present invention. All equivalent changes and improvements made within the scope of the present invention application shall still fall within the scope covered by the present invention.

Claims

1. An antistatic polyethylene composite film, characterized in that: By mass parts, it includes the following raw materials: 100 parts of low-density polyethylene, 5 - 9 parts of high-density polyethylene, 10 - 20 parts of maleic anhydride grafted polyethylene, 8 - 15 parts of polyvinyl alcohol modified material, 3 - 5 parts of antistatic modified carbon black, 0.5 - 1 part of antioxidant, and 1 - 2 parts of dispersant; The preparation method of the antistatic modified carbon black includes the following steps: S1. Mix oxidized carbon black, phosphoric acid, and 3-dimethylamino-1-propylamine evenly, raise the temperature, stir and mix, and react. After the reaction ends, adjust the pH to neutral with sodium hydroxide solution, conduct vacuum distillation, wash with deionized water and absolute ethanol, and dry in vacuum at 60 °C for 24 h to obtain modified carbon black; S2. Disperse the modified carbon black in isopropanol, mix evenly, add long-chain haloalkane, heat under reflux, and react. After the reaction ends, conduct vacuum distillation, wash with acetone, and dry in vacuum at 60 °C for 12 h to obtain antistatic modified carbon black; The polyvinyl alcohol modified material is prepared by the following steps: Polyvinyl alcohol, vinyl-functionalized carbon nanotubes, and trimethylallyl ammonium chloride undergo a polymerization reaction under the action of an initiator to obtain the polyvinyl alcohol modified material; The initiator is ammonium cerium(IV) sulfate.

2. The antistatic polyethylene composite film according to claim 1, wherein: In S1, the mass ratio of oxidized carbon black, phosphoric acid, and 3-dimethylamino-1-propylamine is 100:700 - 900:120 - 150, the reaction temperature is 145 - 155 °C, and the reaction time is 10 - 12 h.

3. The antistatic polyethylene composite film according to claim 1, characterized in that: In S2, the mass ratio of modified carbon black, isopropanol, and long-chain haloalkane is 100:4500 - 5500:280 - 350, the reaction temperature is 80 - 90 °C, and the reaction time is 24 - 36 h.

4. The antistatic polyethylene composite film according to claim 1, wherein: In S2, the long-chain haloalkane is bromoalkane or chloroalkane with 12 - 16 carbon atoms.

5. An antistatic polyethylene composite film according to claim 1, characterized in that: The preparation method of the polyvinyl alcohol modified material includes the following steps: Step 1. Ultrasonically disperse carbon nanotubes in absolute ethanol. After dispersing evenly, add γ-methacryloxypropyltrimethoxysilane, stir and mix, heat, and react. After the reaction ends, conduct suction filtration, wash with absolute ethanol, and dry in vacuum at 60 °C for 12 h to obtain vinyl-functionalized carbon nanotubes; Step 2. Mix polyvinyl alcohol and deionized water, add an initiator, vinyl-functionalized carbon nanotubes, and trimethylallyl ammonium chloride, stir and mix, and react. After the reaction ends, adjust the pH to 6 with hydrochloric acid, conduct suction filtration, wash with acetone and deionized water, and dry in an oven at 60 °C for 12 h to obtain the polyvinyl alcohol modified material.

6. The antistatic polyethylene composite film according to claim 5, characterized in that: In Step 2, the mass ratio of polyvinyl alcohol, deionized water, initiator, vinyl-functionalized carbon nanotubes, and trimethylallyl ammonium chloride is 100:1200 - 1800:0.03 - 0.1:4 - 9:5 - 10, the reaction temperature is 55 - 65 °C, and the reaction time is 4 - 6 h.

7. An antistatic polyethylene composite film according to claim 5, characterized in that: The initiator in Step 2 is ammonium cerium(IV) sulfate.

8. A method for preparing an antistatic polyethylene composite film according to any one of claims 1-7, characterized in that: It includes the following steps: Low-density polyethylene, high-density polyethylene, maleic anhydride grafted polyethylene, polyvinyl alcohol modified material, antistatic modified carbon black, antioxidant, and dispersant are vacuum dried at 80 °C for 2 h. After drying, they are mixed evenly, melt blended in a twin-screw extruder, extruded into pellets, and then subjected to blown film treatment to obtain an antistatic polyethylene composite film.

9. The preparation method of an antistatic polyethylene composite film according to claim 8, wherein: The processing technology of the twin-screw extruder includes: the heating temperatures of the first to sixth zones of the twin-screw extruder are 160 - 180 °C, 185 - 205 °C, 210 - 230 °C, 230 - 240 °C, 220 - 230 °C, and 200 - 210 °C respectively, and the rotation speed is 200 - 300 r / min. During the blown film treatment, the die head temperature is 190 - 200 °C, and the blow-up ratio is 2.5 - 3.

0.

10. The preparation method of an antistatic polyethylene composite film according to claim 8, characterized in that: The antioxidant consists of antioxidant 1010 and antioxidant 168 with a mass ratio of 3:2; the dispersant is polyethylene wax.

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