Antistatic polyethylene composite film and preparation method thereof

Abstract

The invention relates to the technical field of polymeric membrane materials, and particularly discloses an antistatic polyethylene composite membrane and a preparation method thereof. Comprising the following raw materials in parts by weight: 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 a polyvinyl alcohol modified material, 3-5 parts of antistatic modified carbon black, 0.5-1 part of an antioxidant and 1-2 parts of a dispersing agent, the polyethylene composite film has excellent dispersibility, can effectively enhance the mechanical properties of the polyethylene composite film through the synergistic effect of physical filling and chemical grafting, forms a layer of conductive network structure, namely a conductive film, on the surface of the material through the combined effect of the polyethylene composite film and the antistatic agent, prevents the generation and accumulation of static electricity, and has good compatibility among the raw materials. And the material has excellent mechanical property and antistatic property.

Description

Technical Field

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

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

[0003] In order to solve this problem, researchers have developed a variety of antistatic polyethylene films. Chinese patent application CN105216349A discloses a method for preparing an antistatic polyethylene film, which uses a ball mill to prepare surface-modified nano-conductive carbon black, which is pre-mixed with linear low-density polyethylene through a ball mill, and then blended with linear low-density polyethylene and metallocene polyethylene for extrusion and granulation. The pellets are added to a blow molding machine for blow molding to form an antistatic polyethylene film. The polyethylene film has good antistatic properties by adding conductive fillers, but the dispersibility of conductive carbon black is poor, which affects the mechanical properties of the polyethylene film. At the same time, there are compatibility issues when metallocene polyethylene is introduced into the pellets, and phase separation is easily caused during blending, which affects the performance of the polyethylene film. Chinese patent application CN106084432A discloses an antistatic PE film and a preparation method thereof, wherein the antistatic PE film includes a surface film, a middle film and a bottom film from top to bottom, and 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 film material, and a softener accounting for 1-2% of the total amount of the middle film material are mixed and fully stirred and uniformly prepared by three-layer co-extrusion to obtain an antistatic PE film. The PE film has good flexibility and good mechanical properties. However, the PE film is prone to the problem of antistatic agent migration failure in long-term use, resulting in insufficient antistatic performance. The design of the three-layer film is adopted, and no antistatic agent is added to the surface film and the bottom film, resulting in poor antistatic performance.

[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] 1. Technical issues to be resolved In view of the deficiencies in the prior art, the present invention provides an antistatic polyethylene composite film and a preparation method thereof, which solves the problems of poor antistatic performance and general mechanical properties of the polyethylene composite film.

[0006] (II) Technical solution In order to achieve the above-mentioned purpose, the present invention discloses an antistatic polyethylene composite film, which comprises the following raw materials, measured 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 parts of antioxidant, and 1-2 parts of dispersant.

[0007] The preparation method of the antistatic modified carbon black comprises the following steps: S1. Evenly mix oxidized carbon black, phosphoric acid and 3-dimethylamino-1-propylamine, heat up, stir and mix to react. After the reaction is completed, adjust the pH to neutral with sodium hydroxide solution, perform vacuum distillation, wash with deionized water and anhydrous ethanol, and vacuum dry at 60° C. for 24 h to obtain modified carbon black. S2. Disperse the modified carbon black in isopropanol, mix well, add long-chain halogenated alkane, heat under reflux to react, and after the reaction is completed, distill under reduced pressure, wash with acetone, and vacuum dry at 60°C for 12 hours to obtain antistatic modified carbon black.

[0008] The polyvinyl alcohol modified material components include polyvinyl alcohol and carbon nanotubes.

[0009] Preferably, the mass ratio of oxidized carbon black, phosphoric acid and 3-dimethylamino-1-propylamine in S1 is 100:700-900:120-150.

[0010] Preferably, the reaction temperature in S1 is 145-155° C., and the reaction time is 10-12 h.

[0011] Preferably, the concentration of the sodium hydroxide solution in S1 is 0.05 mol / L.

[0012] Preferably, the preparation method of the oxidized carbon black in S1 is as follows: mix carbon black and nitric acid solution in a mass ratio of 100:3000, wherein the concentration of the nitric acid solution is 4 mol / L, heat to 90°C, stir, react for 12 hours, and after the reaction is completed, filter, wash with deionized water and anhydrous ethanol, and dry in a vacuum drying oven at 60°C for 12 hours to obtain oxidized carbon black.

[0013] Preferably, the mass ratio of modified carbon black, isopropanol and long-chain halogenated alkane in S2 is 100:4500-5500:280-350, the reaction temperature is 80-90° C., and the reaction time is 24-36 h.

[0014] Preferably, the long-chain halogenated alkane in S2 is a brominated alkane or a chloroalkane having 12 to 16 carbon atoms.

[0015] Furthermore, the long-chain halogenated alkane in S2 preferably includes any one of dodecane bromide, tetradecane bromide, hexadecane bromide, dodecane chloride, tetradecane chloride, and hexadecane chloride.

[0016] Preferably, the preparation method of the polyvinyl alcohol modified material comprises the following steps: Step 1, ultrasonically dispersing carbon nanotubes in anhydrous ethanol, adding γ-methacryloxypropyltrimethoxysilane after uniform dispersion, stirring and mixing, heating, reacting, and after the reaction is completed, filtering, washing with anhydrous ethanol, and vacuum drying at 60° C. for 12 h to obtain olefinic carbon nanotubes; Step 2: Mix polyvinyl alcohol and deionized water, add initiator, olefinated carbon nanotubes and trimethylallyl ammonium chloride, stir and mix, react, and after the reaction, use hydrochloric acid to adjust the pH to 6, filter, wash with acetone and deionized water, and dry in a drying oven at 60°C for 12 hours to obtain a polyvinyl alcohol modified material.

[0017] Preferably, in the step 1, the mass ratio of anhydrous ethanol, carbon nanotubes and γ-methacryloxypropyltrimethoxysilane is 6000-6500:100:20-30.

[0018] Preferably, the reaction temperature in step 1 is 65-75° C., and the reaction time is 4-6 h.

[0019] Preferably, in the step 2, the mass ratio of polyvinyl alcohol, deionized water, initiator, olefinated carbon nanotubes and trimethylallylammonium chloride is 100:1200-1800:0.03-0.1:4-9:5-10.

[0020] Preferably, the reaction temperature in step 2 is 55-65° C., and the reaction time is 4-6 h.

[0021] Preferably, the initiator in step 2 is ammonium cerium sulfate.

[0022] A method for preparing the antistatic polyethylene composite film comprises 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 hours, mixed evenly after drying, melt-blended in a twin-screw extruder, extruded into granules, and then subjected to film blowing treatment to obtain an antistatic polyethylene composite film.

[0023] Preferably, the processing technology of the twin-screw extruder includes: the heating temperatures of zones 1 to 6 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 200-300r / min. During the film blowing process, the die head temperature is 190-200°C and the blowing ratio is 2.5-3.0.

[0024] Preferably, the antioxidant consists of antioxidant 1010 and antioxidant 168 in a mass ratio of 3:2; and the dispersant is polyethylene wax.

[0025] 3. Beneficial technical effects Compared with the prior art, the present invention has the following beneficial effects: (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 oxidatively modified to introduce carboxyl groups on the surface of the carbon black to obtain oxidized carbon black, and 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 reacts with long-chain halogenated alkanes to undergo quaternization, and quaternary ammonium salts are introduced on the surface of the carbon black to reduce the surface polarity, thereby obtaining antistatic modified carbon black. The long-chain alkyl group introduced on carbon black can effectively reduce the agglomeration of carbon black, and can be evenly dispersed in the polyethylene matrix, effectively avoiding the mechanical defects caused by agglomeration, and can effectively maintain the uniformity and ductility of the film. At the same time, the introduced amide bond works together with the quaternary ammonium salt to construct an ion conductive pathway, reduce surface resistivity, inhibit static electricity accumulation, and improve the antistatic durability of the polyethylene composite film. The antistatic modified carbon black can form a stable conductive network in the polyethylene matrix, avoiding the performance degradation caused by the migration of traditional antistatic agents.

[0026] (2) In the present invention, γ-methacryloxypropyltrimethoxysilane is used to modify carbon nanotubes to obtain olefinic carbon nanotubes. Ammonium cerium sulfate is used as an initiator, and the ammonium cerium sulfate decomposes to generate free radicals, which initiate the graft polymerization of polyvinyl alcohol, olefinic 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 the carbon nanotubes and grafting them onto polyvinyl alcohol, the interfacial bonding force with the polyethylene matrix is ​​enhanced, the stress concentration point is reduced, and the crack propagation is effectively avoided. Further, a rigid support is formed to inhibit the slip of the polyethylene segment and enhance the creep resistance of the material. At the same time, carbon nanotubes have excellent conductive properties and can effectively inhibit static electricity 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 slip of polyethylene molecules and improving the creep resistance and durability of the matrix. The three-dimensional network of polyvinyl alcohol-carbon nanotubes-quaternary ammonium salts formed in the polyvinyl alcohol modified material can improve the conductivity of carbon nanotubes and the antistatic property of quaternary ammonium salts. 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, thereby 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 path. The quaternary ammonium salt is fixed to the matrix through covalent bonds, effectively avoiding migration and loss, and has antistatic durability. The modified carbon black and the polyvinyl alcohol modified material work synergistically to construct a dual-pathway conductive network to achieve rapid dissipation of electrostatic charges.

[0027] (3) The preparation method of the polyethylene composite film of the present invention is simple. The low-density polyethylene has good toughness and excellent film-forming properties, and the high-density polyethylene has excellent strength and rigidity. The two are blended and can effectively balance the mechanical properties through synergistic effect, and the mechanical properties of the prepared polyethylene composite film are improved. Carbon black and carbon nanotubes can effectively enhance the mechanical properties of the polyethylene composite film through physical filling and chemical grafting synergistic effect, and can effectively inhibit the accumulation of static electricity. Together with quaternary ammonium salts, a conductive network structure, i.e., a conductive film, is formed on the surface of the material, which prevents the generation and accumulation of static electricity, further improves the antistatic ability of the matrix, and the antistatic agent is not easy to migrate, and the antistatic performance is long-lasting. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. Example 1

[0029] A method for preparing an antistatic polyethylene composite film comprises the following steps: By mass, 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 parts of antioxidant, and 1 part of dispersant polyethylene wax were weighed, wherein the antioxidant consisted of antioxidant 1010 and antioxidant 168 in a mass ratio of 3:2. The mixture was vacuum dried at 80°C for 2h. After drying, the mixture was mixed evenly and melt-blended in a twin-screw extruder. The heating temperatures of zones 1 to 6 of the twin-screw extruder were 160°C, 185°C, 210°C, 230°C, 220°C, and 200°C, respectively. The rotation speed was 200r / min. The mixture was extruded and granulated, and then film blowing was carried out. During the film blowing process, the die head temperature was 190°C and the blow-up ratio was 2.5 to obtain an antistatic polyethylene composite film.

[0030] The preparation method of antistatic modified carbon black comprises the following steps: S1. Evenly mix oxidized carbon black, phosphoric acid and 3-dimethylamino-1-propylamine in a mass ratio of 100:700:120, heat up, stir and mix, react at a temperature of 145° C. and a reaction time of 12 h. After the reaction, adjust the pH to neutral with a sodium hydroxide solution having a concentration of 0.05 mol / L, perform vacuum distillation, wash with deionized water and anhydrous ethanol, and vacuum dry at 60° C. for 24 h to obtain modified carbon black. S2. Disperse the modified carbon black in isopropanol, mix well, add long-chain halogenated alkane hexadecane chloride, wherein the mass ratio of the modified carbon black, isopropanol and hexadecane chloride is 100:4500:280, heat and reflux to react, the reaction temperature is 80°C, the reaction time is 24h, after the reaction is completed, distill under reduced pressure, wash with acetone, and vacuum dry at 60°C for 12h to obtain antistatic modified carbon black.

[0031] The preparation method of the polyvinyl alcohol modified material comprises the following steps: Step 1, ultrasonically disperse the carbon nanotubes in anhydrous ethanol, and after uniform dispersion, add γ-methacryloxypropyltrimethoxysilane, wherein the mass ratio of anhydrous ethanol, carbon nanotubes, and γ-methacryloxypropyltrimethoxysilane is 6000:100:20, stir and mix, heat, and react at a temperature of 65° C. for 6 hours. After the reaction is completed, filter, wash with anhydrous ethanol, and vacuum dry at 60° C. for 12 hours to obtain olefinated carbon nanotubes; Step 2: Stir and mix polyvinyl alcohol, deionized water, initiator ammonium cerium sulfate, olefinated carbon nanotubes and trimethylallyl ammonium chloride in a mass ratio of 100:1200:0.03:4:5 to react at a temperature of 55°C for 6 hours. After the reaction, adjust the pH to 6 with hydrochloric acid, filter, wash with acetone and deionized water, and dry in a drying oven at 60°C for 12 hours to obtain a polyvinyl alcohol modified material. Example 2

[0032] A method for preparing an antistatic polyethylene composite film comprises the following steps: By mass, 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 parts of antioxidant, and 1.5 parts of dispersant polyethylene wax were weighed, wherein the antioxidant consisted of antioxidant 1010 and antioxidant 168 in a mass ratio of 3:2. The mixture was vacuum dried at 80°C for 2h. After drying, the mixture was mixed evenly and melt-blended in a twin-screw extruder. The heating temperatures of zones 1 to 6 of the twin-screw extruder were 170°C, 195°C, 220°C, 235°C, 225°C, and 205°C, respectively. The rotation speed was 240r / min. The mixture was extruded and granulated, and then film blowing was performed. During the film blowing process, the die head temperature was 195°C and the blow-up ratio was 2.8 to obtain an antistatic polyethylene composite film.

[0033] The preparation method of antistatic modified carbon black comprises the following steps: S1. Evenly mix oxidized carbon black, phosphoric acid and 3-dimethylamino-1-propylamine in a mass ratio of 100:800:130, heat up, stir and mix, react at a temperature of 150° C. for 11 h. After the reaction, adjust the pH to neutral with a sodium hydroxide solution with a concentration of 0.05 mol / L, perform vacuum distillation, wash with deionized water and anhydrous ethanol, and vacuum dry at 60° C. for 24 h to obtain modified carbon black. S2. Disperse the modified carbon black in isopropanol, mix well, add long-chain halogenated alkane hexadecane chloride, wherein the mass ratio of the modified carbon black, isopropanol and hexadecane chloride is 100:5000:300, heat and reflux to react, after the reaction is completed, distill under reduced pressure, wash with acetone, and vacuum dry at 60°C for 12 hours to obtain antistatic modified carbon black.

[0034] The preparation method of the polyvinyl alcohol modified material comprises the following steps: Step 1, ultrasonically dispersing carbon nanotubes in anhydrous ethanol, after uniform dispersion, adding γ-methacryloxypropyltrimethoxysilane, wherein the mass ratio of anhydrous ethanol, carbon nanotubes, and γ-methacryloxypropyltrimethoxysilane is 6200:100:24, stirring and mixing, heating, reacting, the reaction temperature is 70° C., the reaction time is 5 h, after the reaction is completed, filtering, washing with anhydrous ethanol, and vacuum drying at 60° C. for 12 h to obtain olefinated carbon nanotubes; Step 2: Stir and mix polyvinyl alcohol, deionized water, initiator ammonium cerium sulfate, olefinated carbon nanotubes and trimethylallyl ammonium chloride in a mass ratio of 100:1500:0.05:7:6 to react at a temperature of 60°C for 5 hours. After the reaction, adjust the pH to 6 with hydrochloric acid, filter, wash with acetone and deionized water, and dry in a drying oven at 60°C for 12 hours to obtain a polyvinyl alcohol modified material. Example 3

[0035] A method for preparing an antistatic polyethylene composite film comprises the following steps: By mass, 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 parts of antioxidant, and 1.5 parts of dispersant polyethylene wax were weighed, wherein the antioxidant consisted of antioxidant 1010 and antioxidant 168 in a mass ratio of 3:2. The mixture was vacuum dried at 80°C for 2h. After drying, the mixture was mixed evenly and melt-blended in a twin-screw extruder. The heating temperatures of zones 1 to 6 of the twin-screw extruder were 170°C, 195°C, 220°C, 235°C, 225°C, and 205°C, respectively. The rotation speed was 240r / min. The mixture was extruded and granulated, and then film blowing was performed. During the film blowing process, the die head temperature was 195°C and the blow-up ratio was 2.8 to obtain an antistatic polyethylene composite film.

[0036] The preparation method of antistatic modified carbon black comprises the following steps: S1. Evenly mix oxidized carbon black, phosphoric acid and 3-dimethylamino-1-propylamine in a mass ratio of 100:800:140, heat up, stir and mix, react at a temperature of 150° C. for 11 h. After the reaction, adjust the pH to neutral with a sodium hydroxide solution having a concentration of 0.05 mol / L, perform vacuum distillation, wash with deionized water and anhydrous ethanol, and vacuum dry at 60° C. for 24 h to obtain modified carbon black. S2. Disperse the modified carbon black in isopropanol, mix well, add long-chain halogenated alkane hexadecane chloride, wherein the mass ratio of the modified carbon black, isopropanol and hexadecane chloride is 100:5000:320, heat under reflux to react, and after the reaction is completed, distill under reduced pressure, wash with acetone, and vacuum dry at 60°C for 12 hours to obtain antistatic modified carbon black.

[0037] The preparation method of the polyvinyl alcohol modified material comprises the following steps: Step 1, ultrasonically disperse the carbon nanotubes in anhydrous ethanol, and after uniform dispersion, add γ-methacryloxypropyltrimethoxysilane, wherein the mass ratio of anhydrous ethanol, carbon nanotubes, and γ-methacryloxypropyltrimethoxysilane is 6200:100:28, stir and mix, heat, and react at a temperature of 70° C. for 5 hours. After the reaction is completed, filter, wash with anhydrous ethanol, and vacuum dry at 60° C. for 12 hours to obtain olefinated carbon nanotubes; Step 2: Stir and mix polyvinyl alcohol, deionized water, initiator ammonium cerium sulfate, olefinated carbon nanotubes and trimethylallyl ammonium chloride in a mass ratio of 100:1500:0.08:8:8 to react at a temperature of 60°C for 5 hours. After the reaction, adjust the pH to 6 with hydrochloric acid, filter, wash with acetone and deionized water, and dry in a drying oven at 60°C for 12 hours to obtain a polyvinyl alcohol modified material. Example 4

[0038] A method for preparing an antistatic polyethylene composite film comprises the following steps: By mass, 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 parts of antioxidant, and 1.8 parts of dispersant polyethylene wax were weighed, wherein the antioxidant consisted of antioxidant 1010 and antioxidant 168 in a mass ratio of 3:2. The mixture was vacuum dried at 80°C for 2h. After drying, the mixture was mixed evenly and melt-blended in a twin-screw extruder. The heating temperatures of zones 1 to 6 of the twin-screw extruder were 175°C, 200°C, 225°C, 235°C, 225°C, and 205°C, respectively. The rotation speed was 260r / min. The mixture was extruded and granulated, and then film blowing was performed. During the film blowing process, the die head temperature was 195°C and the blow-up ratio was 2.8 to obtain an antistatic polyethylene composite film.

[0039] The preparation method of the antistatic modified carbon black and the polyvinyl alcohol modified material is the same as the preparation method of the antistatic modified carbon black and the polyvinyl alcohol modified material in Example 3. Example 5

[0040] A method for preparing an antistatic polyethylene composite film comprises the following steps: By mass, 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 were weighed, wherein the antioxidant consisted of antioxidant 1010 and antioxidant 168 in a mass ratio of 3:2. The mixture was vacuum dried at 80°C for 2h. After drying, the mixture was mixed evenly and melt-blended in a twin-screw extruder. The heating temperatures of zones 1 to 6 of the twin-screw extruder were 180°C, 205°C, 230°C, 240°C, 230°C, and 210°C, respectively. The rotation speed was 300r / min. The mixture was extruded and granulated, and then film blowing was performed. During the film blowing process, the die head temperature was 200°C and the blow-up ratio was 3.0 to obtain an antistatic polyethylene composite film.

[0041] The preparation method of antistatic modified carbon black comprises the following steps: S1. Evenly mix oxidized carbon black, phosphoric acid and 3-dimethylamino-1-propylamine in a mass ratio of 100:900:150, heat up, stir and mix, react at a temperature of 155° C. and a reaction time of 12 h. After the reaction, adjust the pH to neutral with a sodium hydroxide solution with a concentration of 0.05 mol / L, perform vacuum distillation, wash with deionized water and anhydrous ethanol, and vacuum dry at 60° C. for 24 h to obtain modified carbon black. S2. Disperse the modified carbon black in isopropanol, mix well, add long-chain halogenated alkane hexadecane chloride, wherein the mass ratio of the modified carbon black, isopropanol and hexadecane chloride is 100:5500:350, heat to reflux, react, and after the reaction is completed, distill under reduced pressure, wash with acetone, and vacuum dry at 60°C for 12 hours to obtain antistatic modified carbon black.

[0042] The preparation method of the polyvinyl alcohol modified material comprises the following steps: Step 1, ultrasonically disperse the carbon nanotubes in anhydrous ethanol, and after uniform dispersion, add γ-methacryloxypropyltrimethoxysilane, wherein the mass ratio of anhydrous ethanol, carbon nanotubes, and γ-methacryloxypropyltrimethoxysilane is 6500:100:30, stir and mix, heat, and react at a temperature of 75° C. for 6 hours. After the reaction is completed, filter, wash with anhydrous ethanol, and vacuum dry at 60° C. for 12 hours to obtain olefinated carbon nanotubes; Step 2: Stir and mix polyvinyl alcohol, deionized water, initiator ammonium cerium sulfate, olefinated carbon nanotubes and trimethylallyl ammonium chloride in a mass ratio of 100:1800:0.1:9:10 to react at a temperature of 65°C for 6 hours. After the reaction, adjust the pH to 6 with hydrochloric acid, filter, wash with acetone and deionized water, and dry in a drying oven at 60°C for 12 hours to obtain a polyvinyl alcohol modified material. Comparative Example 1

[0043] A method for preparing a polyethylene composite film comprises the following steps: By mass, 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 parts of antioxidant, and 1.8 parts of dispersant polyethylene wax were weighed, wherein the antioxidant consisted of antioxidant 1010 and antioxidant 168 in a mass ratio of 3:2. The mixture was vacuum dried at 80°C for 2h. After drying, the mixture was mixed evenly and melt-blended in a twin-screw extruder. The heating temperatures of zones 1 to 6 of the twin-screw extruder were 175°C, 200°C, 225°C, 235°C, 225°C, and 205°C, respectively. The rotation speed was 260r / min. The mixture was extruded and granulated, and then film blowing was performed. During the film blowing process, the die head temperature was 195°C and the blow-up ratio was 2.8 to obtain a polyethylene composite film.

[0044] The preparation method of the polyvinyl alcohol modified material is the same as the preparation method of the polyvinyl alcohol modified material in Example 3. Comparative Example 2

[0045] A method for preparing a polyethylene composite film comprises the following steps: By mass, 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 parts of antioxidant, and 1.8 parts of dispersant polyethylene wax were weighed, wherein the antioxidant consisted of antioxidant 1010 and antioxidant 168 in a mass ratio of 3:2. The mixture was vacuum dried at 80°C for 2h. After drying, the mixture was mixed evenly and melt-blended in a twin-screw extruder. The heating temperatures of zones 1 to 6 of the twin-screw extruder were 175°C, 200°C, 225°C, 235°C, 225°C, and 205°C, respectively. The rotation speed was 260r / min. The mixture was extruded and granulated, and then film blowing was carried out. During the film blowing process, the die head temperature was 195°C and the blow-up ratio was 2.8 to obtain a polyethylene composite film.

[0046] The preparation method of the antistatic modified carbon black is the same as the preparation method of the antistatic modified carbon black in Example 3.

[0047] The preparation method of oxidized carbon black in the embodiments and comparative examples of the present invention is as follows: carbon black and nitric acid solution in a mass ratio of 100:3000 are mixed, wherein the concentration of the nitric acid solution is 4 mol / L, the temperature is raised to 90°C, stirred, and reacted for 12 hours. After the reaction is completed, the mixture is filtered, washed with deionized water and anhydrous ethanol, and dried in a vacuum drying oven at 60°C for 12 hours to obtain oxidized carbon black.

[0048] The carbon black used in the examples and comparative examples of the present invention was purchased from Qingdao Degussa Chemical Co., Ltd., model carbon black N330; carbon nanotubes were purchased from Beijing Dekedaojin Technology Co., Ltd., model CNT204 carbon nanotubes; low-density polyethylene was purchased from Sinopec Maoming Petrochemical Co., Ltd., model 2426H, melt index of 1.9 g / 10 min, density of 0.9 g / cm 3 High-density polyethylene was purchased from Dongguan Shunyu Chemical Co., Ltd. with the brand name LH606; maleic anhydride grafted polyethylene was purchased from Dongguan Shangyi Plastic Co., Ltd. with the brand name NF358E; polyvinyl alcohol was purchased from Tianjin Alfa Aesar Co., Ltd. with a number average molecular weight of 60,000; other undisclosed reagents were commercially available.

[0049] The polyethylene composite films prepared in Examples 1-5 and Comparative Examples 1-2 were subjected to relevant performance tests, as follows: (1) Antistatic performance test: The polyethylene composite films prepared in Examples 1-5 and Comparative Examples 1-2 were tested for antistatic performance. The test method was based on GB / T 1410-2006 "Test method for volume resistivity and surface resistivity of solid insulating materials", and the surface resistance of the composite films was recorded. (2) Mechanical property test: The polyethylene composite films prepared in Examples 1-5 and Comparative Examples 1-2 were subjected to tensile property tests. The test method was based on GB / T 1040.3-2006 "Determination of tensile properties of plastics 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 films were recorded. The samples were subjected to puncture resistance test based on ASTM F1306 test standard. The puncture needle used had a diameter of 1 mm and a puncture speed of 50 mm / min. Each group of samples was tested three times, and the maximum force value was recorded. The above test results are shown in Table 1: Table 1

[0050] According to the test results in Table 1, it can be seen that the polyethylene composite films prepared in Examples 1-5 have excellent mechanical properties and antistatic properties. The addition of fillers and polyvinyl alcohol can effectively improve the local load-bearing capacity of the matrix. At the same time, the raw materials have excellent interface bonding, stable material properties, high puncture resistance, and high puncture resistance. In Comparative Example 1, the oxidized carbon black was not modified, the dispersibility of the carbon black was poor, the mechanical properties were deteriorated, and no amide bonds and quaternary ammonium salts were introduced on the surface of the carbon black, the antistatic properties were deteriorated, and the corresponding surface resistivity was 2.5×10 11 Ω / sq, tensile strength is 21.3MPa, elongation at break is 305%, and puncture resistance is 57.3N. In Comparative Example 2, the carbon nanotubes were not modified, the dispersion was poor, and they were easy to agglomerate. The surface resistivity of the corresponding sample was 8.4×10 10 Ω / sq, tensile strength is 23.7MPa, elongation at break is 324%, and puncture resistance is 60.5N.

[0051] Although the embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that all equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the present invention.

Claims

1. An antistatic polyethylene composite film, characterized in that: The raw materials include the following by weight: 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 parts of antioxidant, and 1-2 parts of dispersant; The preparation method of the antistatic modified carbon black comprises the following steps: S1. Evenly mix oxidized carbon black, phosphoric acid and 3-dimethylamino-1-propylamine, heat up, stir and mix to react. After the reaction is completed, adjust the pH to neutral with sodium hydroxide solution, perform vacuum distillation, wash with deionized water and anhydrous ethanol, and vacuum dry at 60° C. for 24 h to obtain modified carbon black. S2, dispersing the modified carbon black in isopropanol, mixing evenly, adding a long-chain halogenated alkane, heating under reflux, reacting, and after the reaction is completed, distilling under reduced pressure, washing with acetone, and vacuum drying 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, olefinic carbon nanotubes and trimethylallyl ammonium chloride are polymerized under the action of an initiator to obtain the polyvinyl alcohol modified material.

2. The antistatic polyethylene composite film according to claim 1, characterized in that: The mass ratio of oxidized carbon black, phosphoric acid and 3-dimethylamino-1-propylamine in S1 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: The mass ratio of modified carbon black, isopropanol and long-chain halogenated alkane in S2 is 100:4500-5500:280-350, the reaction temperature is 80-90° C., and the reaction time is 24-36 hours.

4. The antistatic polyethylene composite film according to claim 1, characterized in that: The long-chain halogenated alkane in S2 is a brominated alkane or a chloroalkane having 12 to 16 carbon atoms.

5. The antistatic polyethylene composite film according to claim 1, characterized in that: The preparation method of the polyvinyl alcohol modified material comprises the following steps: Step 1, ultrasonically dispersing carbon nanotubes in anhydrous ethanol, adding γ-methacryloxypropyltrimethoxysilane after uniform dispersion, stirring and mixing, heating, reacting, and after the reaction is completed, filtering, washing with anhydrous ethanol, and vacuum drying at 60° C. for 12 h to obtain olefinic carbon nanotubes; Step 2: Mix polyvinyl alcohol and deionized water, add initiator, olefinated carbon nanotubes and trimethylallyl ammonium chloride, stir and mix, react, and after the reaction, use hydrochloric acid to adjust the pH to 6, filter, wash with acetone and deionized water, and dry in a drying oven at 60°C for 12 hours to obtain a polyvinyl alcohol modified material.

6. The antistatic polyethylene composite film according to claim 5, characterized in that: In the step 2, the mass ratio of polyvinyl alcohol, deionized water, initiator, olefinic carbon nanotubes and trimethylallylammonium 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 hours.

7. The antistatic polyethylene composite film according to claim 5, characterized in that: The initiator in step 2 is ammonium cerium sulfate.

8. A method for preparing an antistatic polyethylene composite film according to any one of claims 1 to 7, characterized in that: The steps include: 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 hours, mixed evenly after drying, melt-blended in a twin-screw extruder, extruded into granules, and then subjected to film blowing treatment to obtain an antistatic polyethylene composite film.

9. The method for preparing an antistatic polyethylene composite film according to claim 8, characterized in that: The processing technology of the twin-screw extruder includes: the heating temperatures of zones 1 to 6 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 200-300r / min. During the film blowing process, the die head temperature is 190-200°C and the blowing ratio is 2.5-3.

0.

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

Images