Flame-retardant polyethylene composite material and preparation method thereof

Abstract

The invention provides a flame-retardant polyethylene composite material and a preparation method thereof, and belongs to the technical field of high polymer materials. The flame-retardant polyethylene composite material is prepared from the following components: polyethylene resin, a multifunctional flame retardant, a lubricant and a flexibilizer, wherein the multifunctional flame retardant is an oligomer formed by polymerizing phosphorus oxychloride serving as an acid source, pentaerythritol serving as a carbon source, 4, 7-bis (4-aminophenyl)-2, 1, 3-benzothiadiazole serving as a gas source and the ultraviolet light absorber, and the flame-retardant polyethylene composite material provided by the invention not only has good flame-retardant property, but also has good flame-retardant property and good flame-retardant property. The polyethylene composite material also shows excellent ultraviolet aging resistance, and the problem that the polyethylene composite material is inflammable and is easily affected by ultraviolet rays to cause aging is effectively solved.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and particularly relates to a flame retardant polyethylene composite material and a preparation method thereof. Background Art

[0002] Polyethylene is a widely used polymer material. It is widely used in many fields because of its light weight, economical price, excellent heat resistance, easy processing and excellent chemical corrosion resistance. The basic structure of low-density polyethylene is composed of two elements, carbon and hydrogen, and forms long-chain macromolecules, so it is flammable. By modifying polyethylene to be flame retardant, its ignition risk can be effectively reduced, and the probability of fire can be reduced from the source. As an important additive to give polyethylene fire resistance, flame retardants are an important part of achieving this effect. At present, the more mature flame retardants used in polyethylene include halogen flame retardants, phosphorus flame retardants, nitrogen flame retardants, silicon flame retardants, and metal hydroxide flame retardants. Among them, although the amount of halogen-containing flame retardants is not large, the effect is significant, and they are widely used due to their moderate price. However, this type of halogen-containing material will release a large amount of toxic gases and smoke when burned, causing secondary pollution.

[0003] Intumescent flame retardants have P, N and C as core components. After thermal decomposition, they can form an expanded porous protective carbon layer on the polymer surface to inhibit heat and oxygen transfer and reduce the production of volatiles. At the same time, they effectively prevent polymer droplets and achieve good flame retardant effects. However, it should be noted that such flame retardants are easily thermally decomposed under ultraviolet radiation, resulting in uneven distribution of flame retardants inside polyethylene composite materials, which in turn affects the mechanical properties of the material. In addition, when polyethylene is used outdoors, it is easily oxidized under ultraviolet radiation, which significantly deteriorates its mechanical properties and shortens its service life.

[0004] Therefore, providing a flame retardant polyethylene composite material with flame retardant and anti-ultraviolet aging properties is a technical problem that needs to be solved urgently in this field. Summary of the invention

[0005] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a flame-retardant polyethylene composite material and a preparation method thereof, which not only has good flame retardant properties, but also has excellent anti-ultraviolet aging properties, effectively solving the problem that the polyethylene composite material is flammable and susceptible to aging caused by ultraviolet rays. Specifically, the technical solution of the present invention includes the following contents:

[0006] A method for preparing a flame retardant polyethylene composite material comprises the following steps:

[0007] The polyethylene resin, the multifunctional flame retardant, the lubricant and the toughening agent are mixed to obtain a mixture, and the mixture is melt-kneaded and granulated to obtain the flame-retardant polyethylene composite material.

[0008] Furthermore, the preparation method of the multifunctional flame retardant comprises the following steps:

[0009] Pentaerythritol is dispersed in chloroform, stirred and heated to 60-70°C in an inert gas protection environment, phosphorus oxychloride is added, refluxed and stirred for reaction for 4-5 hours to obtain bisphosphate diphosphoryl chloride; the bisphosphate diphosphoryl chloride is dispersed in acetonitrile, 4,7-di(4-aminophenyl)-2,1,3-benzothiadiazole and triethylamine are added in an inert gas protection environment, the temperature is raised to 45-100°C at normal pressure, refluxed and stirred for reaction for 8-12 hours, and then washed and dried to obtain the multifunctional flame retardant.

[0010] Furthermore, the weight ratio of pentaerythritol, phosphorus oxychloride and 4,7-bis(4-aminophenyl)-2,1,3-benzothiadiazole is 0.8-1.5:1.5-3:1.2-2.

[0011] Furthermore, the weight ratio of the triethylamine to 4,7-di(4-aminophenyl)-2,1,3-benzothiadiazole is 0.5-0.8:1.

[0012] Furthermore, the inert gas is nitrogen or argon.

[0013] Furthermore, the normal pressure heating adopts a programmed temperature heating method: firstly heating to 45-60°C, reflux stirring and reacting for 3-4 hours, then heating to 90-100°C, reflux stirring and reacting for 5-8 hours.

[0014] Furthermore, the polyethylene resin is a low-density polyethylene resin.

[0015] Furthermore, the lubricant is a mixture of polyethylene wax and silicone powder.

[0016] Furthermore, the silicone powder is silicone additive GTM100.

[0017] Furthermore, the weight ratio of the polyethylene wax to the silicone additive GTM100 is 2:0.5.

[0018] Furthermore, the toughening agent is polyolefin elastomer 8401.

[0019] Furthermore, the weight ratio of the polyethylene resin, the multifunctional flame retardant, the lubricant and the toughening agent is 50-65:20-30:0.25-0.65:0.5-0.9.

[0020] Preferably, the weight ratio of the polyethylene resin, the multifunctional flame retardant, the lubricant and the toughening agent is 60:25:0.4:0.8.

[0021] Furthermore, the mixing time is 5 to 15 minutes.

[0022] Furthermore, the temperature of the melt mixing is 60-80°C and the rotation speed is 600-900 rpm.

[0023] Furthermore, the granulation includes extrusion cooling pelletizing and drying treatment.

[0024] Furthermore, the parameters of the twin-screw extruder during granulation are 160-170°C in zone 1, 170-175°C in zone 2, 175-185°C in zone 3, 185-200°C in zone 4, 200-220°C in zone 5, and the screw speed is 100-200rpm.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] (1) The present invention prepares bisphosphate diphosphoryl chloride by phosphating pentaerythritol and phosphorus oxychloride, and then introduces an ultraviolet absorber 4,7-bis(4-aminophenyl)-2,1,3-benzothiadiazole into the bisphosphate diphosphoryl chloride by a nucleophilic substitution reaction to synthesize an oligomer to prepare a multifunctional flame retardant. The polyethylene composite material added with the multifunctional flame retardant not only exhibits excellent flame retardant properties, but also has excellent anti-ultraviolet oxidation properties, thereby improving the weather resistance of the polyethylene composite material, extending the service life, and reducing resource waste.

[0027] (2) The multifunctional flame retardant in the present invention can meet higher flame retardancy requirements without adding a large amount of phosphorus due to its high phosphorus content. At the same time, the presence of N increases the adhesion of P on the polyethylene composite material, so that the multifunctional flame retardant can form a more stable carbon layer on the surface of the polyethylene composite material when it is thermally decomposed, thereby effectively improving the flame retardancy.

[0028] (3) The low-density polyethylene resin, multifunctional flame retardant, lubricant and toughening agent components of the present invention work synergistically, so that the prepared flame-retardant polyethylene composite material exhibits excellent mechanical properties, which effectively solves the problem in the prior art that the mechanical properties of polyethylene materials are significantly reduced due to the addition of flame retardants. DETAILED DESCRIPTION

[0029] The technical solution of the present invention will be clearly and completely described below through the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0030] Unless otherwise specified, the raw materials and reagents used in the present invention are commercially available or can be prepared by known methods.

[0031] 4,7-Di(4-aminophenyl)-2,1,3-benzothiadiazole was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0032] Preparation Example 1:

[0033] The preparation of multifunctional flame retardant specifically includes the following processes:

[0034] 8 parts by weight of pentaerythritol are dispersed in 100 parts by weight of chloroform, stirred and heated to 60°C in a nitrogen protection environment, 15 parts by weight of phosphorus oxychloride are added, refluxed and stirred for reaction for 5 hours to obtain bisphosphate diphosphoryl chloride; the above bisphosphate diphosphoryl chloride is dispersed in 100 parts by weight of acetonitrile, 12 parts by weight of 4,7-di(4-aminophenyl)-2,1,3-benzothiadiazole and 6 parts by weight of triethylamine are added in a nitrogen protection environment, the temperature is raised to 45°C, refluxed and stirred for reaction for 3 hours, then the temperature is raised to 100°C, refluxed and stirred for reaction for 8 hours, and after the reaction is completed, the multifunctional flame retardant is washed and dried.

[0035] Preparation Example 2:

[0036] The preparation of multifunctional flame retardant specifically includes the following processes:

[0037] 12 parts by weight of pentaerythritol are dispersed in 100 parts by weight of chloroform, stirred and heated to 65°C in an argon gas protection environment, 20 parts by weight of phosphorus oxychloride are added, refluxed and stirred for reaction for 4.5 hours to obtain bisphosphate diphosphoryl chloride; the above bisphosphate diphosphoryl chloride is dispersed in 100 parts by weight of acetonitrile, 13 parts by weight of 4,7-di(4-aminophenyl)-2,1,3-benzothiadiazole and 7.8 parts by weight of triethylamine are added in an argon gas protection environment, the temperature is raised to 50°C, refluxed and stirred for reaction for 3.5 hours, then the temperature is raised to 90°C, refluxed and stirred for reaction for 7 hours, and after the reaction is completed, the multifunctional flame retardant is washed and dried.

[0038] Preparation Example 3:

[0039] The preparation of multifunctional flame retardant specifically includes the following processes:

[0040] 15 parts by weight of pentaerythritol are dispersed in 100 parts by weight of chloroform, stirred and heated to 70°C in a nitrogen protection environment, 30 parts by weight of phosphorus oxychloride are added, refluxed and stirred for reaction for 4 hours to obtain bisphosphate diphosphoryl chloride; the above bisphosphate diphosphoryl chloride is dispersed in 100 parts by weight of acetonitrile, 20 parts by weight of 4,7-di(4-aminophenyl)-2,1,3-benzothiadiazole and 1.6 parts by weight of triethylamine are added in a nitrogen protection environment, the temperature is raised to 60°C, refluxed and stirred for reaction for 4 hours, then the temperature is raised to 95°C, stirred for reaction for 5 hours, and after the reaction is completed, the multifunctional flame retardant is washed and dried.

[0041] Preparation Example 4:

[0042] The preparation of multifunctional flame retardant specifically includes the following processes:

[0043] 10 parts by weight of pentaerythritol are dispersed in 100 parts by weight of chloroform, stirred and heated to 70°C in a nitrogen protection environment, 20 parts by weight of phosphorus oxychloride are added, refluxed and stirred for reaction for 5 hours to obtain bisphosphate diphosphoryl chloride; the above bisphosphate diphosphoryl chloride is dispersed in 100 parts by weight of acetonitrile, 15 parts by weight of 4,7-di(4-aminophenyl)-2,1,3-benzothiadiazole and 12 parts by weight of triethylamine are added in a nitrogen protection environment, the temperature is raised to 60°C, refluxed and stirred for reaction for 4 hours, then the temperature is raised to 100°C, stirred for reaction for 8 hours, and after the reaction is completed, the multifunctional flame retardant is washed and dried.

[0044] Embodiment 1:

[0045] A method for preparing a flame-retardant polyethylene composite material specifically comprises the following steps:

[0046] 50 parts by weight of low-density polyethylene resin, 20 parts by weight of the multifunctional flame retardant obtained in Preparation Example 1, 0.2 parts by weight of polyethylene wax, 0.05 parts by weight of silicone GTM100 and 0.5 parts by weight of polyolefin elastomer 8401 were placed in a high-speed mixer and mixed at 900 rpm for 5 minutes in an environment of 60°C to obtain a mixture, and the mixture was melt-kneaded in a twin-screw extruder, and extrusion cooling, pelletizing and drying were performed. The temperature parameters of each zone of the twin-screw extruder were 160°C for zone one, 170°C for zone two, 175°C for zone three, 185°C for zone four and 200°C for zone five, and the screw speed was 100 rpm to obtain a flame-retardant polyethylene composite material.

[0047] Embodiment 2:

[0048] A method for preparing a flame-retardant polyethylene composite material specifically comprises the following steps:

[0049] 55 parts by weight of low-density polyethylene resin, 25 parts by weight of the multifunctional flame retardant obtained in Preparation Example 2, 0.24 parts by weight of polyethylene wax, 0.06 parts by weight of silicone GTM100 and 0.6 parts by weight of polyolefin elastomer 8401 were placed in a high-speed mixer and mixed at 600 rpm for 10 minutes in an environment of 70°C to obtain a mixture, and the mixture was melt-kneaded in a twin-screw extruder, and extrusion cooling, pelletizing and drying were performed. The temperature parameters of each zone of the twin-screw extruder were 165°C for zone one, 172°C for zone two, 180°C for zone three, 190°C for zone four and 210°C for zone five, and the screw speed was 150 rpm to obtain a flame-retardant polyethylene composite material.

[0050] Embodiment 3:

[0051] A method for preparing a flame-retardant polyethylene composite material specifically comprises the following steps:

[0052] 60 parts by weight of low-density polyethylene resin, 30 parts by weight of the multifunctional flame retardant obtained in Preparation Example 3, 0.52 parts by weight of polyethylene wax, 0.13 parts by weight of silicone GTM100 and 0.9 parts by weight of polyolefin elastomer 8401 were placed in a high-speed mixer and mixed at 600 rpm for 15 minutes in an environment of 80°C to obtain a mixture, and the mixture was melt-kneaded in a twin-screw extruder, and extrusion cooling, pelletizing and drying were performed. The temperature parameters of each zone of the twin-screw extruder were 170°C for zone one, 175°C for zone two, 185°C for zone three, 195°C for zone four and 220°C for zone five, and the screw speed was 180 rpm to obtain a flame-retardant polyethylene composite material.

[0053] Embodiment 4:

[0054] A method for preparing a flame-retardant polyethylene composite material specifically comprises the following steps:

[0055] 60 parts by weight of low-density polyethylene resin, 25 parts by weight of the multifunctional flame retardant obtained in Preparation Example 4, 0.32 parts by weight of polyethylene wax, 0.08 parts by weight of silicone GTM100 and 0.8 parts by weight of polyolefin elastomer 8401 were placed in a high-speed mixer and mixed at 900 rpm for 15 minutes in an environment of 80°C to obtain a mixture, and the mixture was melt-kneaded in a twin-screw extruder, and extrusion cooling, pelletizing and drying were performed. The temperature parameters of each zone of the twin-screw extruder were 170°C for zone one, 175°C for zone two, 185°C for zone three, 200°C for zone four and 220°C for zone five, and the screw speed was 200 rpm to obtain a flame-retardant polyethylene composite material.

[0056] Comparative Example 1:

[0057] A method for preparing a flame-retardant polyethylene composite material specifically comprises the following steps:

[0058] 60 parts by weight of low-density polyethylene resin, 25 parts by weight of ammonium polyphosphate, 0.32 parts by weight of polyethylene wax, 0.08 parts by weight of silicone GTM100 and 0.8 parts by weight of polyolefin elastomer 8401 are placed in a high-speed mixer and mixed at a speed of 900 rpm for 15 minutes in an environment of 80°C to obtain a mixture, the mixture is melt-kneaded in a twin-screw extruder, and extrusion cooling, pelletizing and drying are performed, the temperature parameters of each zone of the twin-screw extruder are 170°C for zone one, 175°C for zone two, 185°C for zone three, 200°C for zone four and 220°C for zone five, and the screw speed is 200 rpm to obtain a flame-retardant polyethylene composite material.

[0059] Comparative Example 2:

[0060] 60 parts by weight of low-density polyethylene resin, 25 parts by weight of the multifunctional flame retardant obtained in Preparation Example 4, 0.32 parts by weight of polyethylene wax and 0.08 parts by weight of silicone GTM100 were placed in a high-speed mixer and mixed at a speed of 900 rpm for 15 minutes in an environment of 80°C to obtain a mixture, and the mixture was melt-kneaded in a twin-screw extruder, and extrusion cooling, pelletizing and drying were performed. The temperature parameters of each zone of the twin-screw extruder were 170°C for zone one, 175°C for zone two, 185°C for zone three, 200°C for zone four and 220°C for zone five, and the screw speed was 200 rpm to obtain a flame-retardant polyethylene composite material.

[0061] Comparative Example 3:

[0062] A method for preparing a flame-retardant polyethylene composite material specifically comprises the following steps:

[0063] 60 parts by weight of low-density polyethylene resin, 25 parts by weight of ammonium polyphosphate, 5 parts by weight of UV-531, 0.32 parts by weight of polyethylene wax, 0.08 parts by weight of silicone GTM100 and 0.8 parts by weight of polyolefin elastomer 8401 are placed in a high-speed mixer and mixed at a speed of 900 rpm for 15 minutes in an environment of 80°C to obtain a mixture, the mixture is melt-kneaded in a twin-screw extruder, and extrusion cooling, pelletizing and drying are performed. The temperature parameters of each zone of the twin-screw extruder are 170°C for zone one, 175°C for zone two, 185°C for zone three, 200°C for zone four, and 220°C for zone five. The screw speed is 200 rpm to obtain a flame-retardant polyethylene composite material.

[0064] Comparative Example 3:

[0065] 60 parts by weight of low-density polyethylene resin, 25 parts by weight of the multifunctional flame retardant obtained in Preparation Example 4 and 0.8 parts by weight of polyolefin elastomer 8401 are placed in a high-speed mixer and mixed at 900 rpm for 15 minutes in an environment of 80°C to obtain a mixture, and the mixture is melt-kneaded in a twin-screw extruder, and extrusion cooling, pelletizing and drying are performed. The temperature parameters of each zone of the twin-screw extruder are 170°C for zone one, 175°C for zone two, 185°C for zone three, 200°C for zone four, and 220°C for zone five. The screw speed is 200 rpm to obtain a flame-retardant polyethylene composite material.

[0066] Comparative Example 4:

[0067] 60 parts by weight of low-density polyethylene resin and 25 parts by weight of the multifunctional flame retardant obtained in Preparation Example 4 were placed in a high-speed mixer and mixed at a speed of 900 rpm for 15 minutes in an environment of 80°C to obtain a mixture, and the mixture was melt-kneaded in a twin-screw extruder, and extrusion cooling, pelletizing and drying were performed. The temperature parameters of each zone of the twin-screw extruder were 170°C for zone one, 175°C for zone two, 185°C for zone three, 200°C for zone four and 220°C for zone five, and the screw speed was 200 rpm to obtain a flame-retardant polyethylene composite material.

[0068] Test Example 1: Anti-ultraviolet aging test

[0069] The flame-retardant polyethylene composite materials prepared in Examples 1 to 4 and Comparative Examples 1 to 4 were injection molded into plates with a thickness of 4 mm, and cut into samples with a width of 10 mm and a length of 80 mm.

[0070] Referring to the method in GB / T16422.3-2014, the flame-retardant polyethylene composite materials prepared in Examples 1 to 4 and Comparative Examples 1 to 4 were subjected to aging treatment, and a UVA-340 lamp was used for 30-day exposure cycle irradiation according to Method A Cycle No. 1. Referring to the method in GB / T1043.1-2008, the impact properties of the flame-retardant polyethylene composite materials prepared in Examples 1 to 4 and Comparative Examples 1 to 4 before and after aging treatment were tested.

[0071] Impact strength retention rate = impact strength after aging / impact strength before aging

[0072] Table 1. Test results of anti-ultraviolet aging of flame-retardant polyethylene composite materials prepared in Examples 1 to 4 and Comparative Examples 1 to 4

[0073]

[0074] According to the test results in Table 1, it can be concluded that the flame-retardant polyethylene composite materials prepared in Examples 1 to 4 of the present invention have a higher impact strength retention rate than that of Comparative Examples 1 to 4 after 30 days of aging treatment, which indicates that the flame-retardant polyethylene composite materials prepared in the present invention have a more superior anti-ultraviolet aging performance and can effectively extend the service life of the flame-retardant polyethylene composite materials. In Comparative Example 3, the multifunctional flame retardant is replaced with an intumescent flame retardant and an ultraviolet absorber, and the impact strength retention rate of the flame-retardant polyethylene composite materials prepared in Examples 1 to 4 after aging is still higher than that of Comparative Example 3, which indicates that the oligomer formed by 4,7-bis(4-aminophenyl)-2,1,3-benzothiadiazole and bisphosphate diphosphoryl chloride has a synergistic effect, which can more effectively absorb and scatter ultraviolet rays and improve the anti-ultraviolet aging performance of the flame-retardant polyethylene composite materials.

[0075] Test Example 2: Performance Characterization

[0076] The flame retardant polyethylene composite materials prepared in Examples 1 to 4 and Comparative Examples 1 to 4 were tested for relevant performance indicators. The test results are shown in Table 2.

[0077] Table 2. Performance indicators of flame-retardant polyethylene composite materials prepared in Examples 1 to 4 and Comparative Examples 1 to 4

[0078]

[0079] According to the results in Table 2, the present invention uses phosphorus oxychloride as an acid source, pentaerythritol as a carbon source, and 4,7-bis(4-aminophenyl)-2,1,3-benzothiadiazole as a gas source and an ultraviolet absorber to form a multifunctional flame retardant. The flame-retardant polyethylene composite material is prepared by a melt blending process, so that the prepared flame-retardant polyethylene composite material has excellent flame retardant properties and effectively solves the problem of molten droplets. In addition, the present invention reasonably proportions each component so that the flame-retardant polyethylene composite material finally obtained exhibits good mechanical properties, thereby overcoming the problem in the prior art that adding flame retardants to polyethylene materials will lead to a decrease in the mechanical properties of the product.

[0080] The above-described embodiments provide a detailed description of the technical solutions and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected.

Claims

1. A method for preparing a flame retardant polyethylene composite material, characterized in that: The following steps are involved: The polyethylene resin, the multifunctional flame retardant, the lubricant and the toughening agent are mixed to obtain a mixture, and the mixture is melt-kneaded and granulated to obtain the flame-retardant polyethylene composite material.

2. The method for preparing a flame retardant polyethylene composite material according to claim 1, characterized in that: The preparation method of the multifunctional flame retardant comprises the following steps: Pentaerythritol is dispersed in chloroform, stirred and heated to 60-70°C in an inert gas protection environment, phosphorus oxychloride is added, refluxed and stirred for reaction for 4-5 hours to obtain bisphosphate diphosphoryl chloride; the bisphosphate diphosphoryl chloride is dispersed in acetonitrile, 4,7-di(4-aminophenyl)-2,1,3-benzothiadiazole and triethylamine are added in an inert gas protection environment, the temperature is raised to 45-100°C at normal pressure, refluxed and stirred for reaction for 8-12 hours, and then washed and dried to obtain the multifunctional flame retardant.

3. The method for preparing a flame retardant polyethylene composite material according to claim 2, characterized in that: The weight ratio of pentaerythritol, phosphorus oxychloride and 4,7-bis(4-aminophenyl)-2,1,3-benzothiadiazole is 0.8-1.5:1.5-3:1.2-2.

4. The method for preparing a flame retardant polyethylene composite material according to claim 2, characterized in that: The inert gas is nitrogen or argon.

5. The method for preparing a flame retardant polyethylene composite material according to claim 2, characterized in that: The normal pressure heating adopts a programmed heating method: firstly heating to 45-60° C., reflux stirring and reacting for 3-4 hours, then heating to 90-100° C., reflux stirring and reacting for 5-8 hours.

6. The method for preparing a flame retardant polyethylene composite material according to claim 1, characterized in that: The polyethylene resin is a low-density polyethylene resin.

7. The method for preparing a flame retardant polyethylene composite material according to claim 1, characterized in that: The lubricant is a mixture of polyethylene wax and silicone powder.

8. The method for preparing a flame retardant polyethylene composite material according to claim 1, characterized in that: The weight ratio of the polyethylene resin, the multifunctional flame retardant, the lubricant and the toughening agent is 50-65:20-30:0.25-0.65:0.5-0.

9.

9. The method for preparing a flame-retardant polyethylene composite material according to claim 1, characterized in that: The parameters of the twin-screw extruder during granulation are: 160-170°C in zone 1, 170-175°C in zone 2, 175-185°C in zone 3, 185-200°C in zone 4, 200-220°C in zone 5, and the screw speed is 100-200rpm.

10. A flame-retardant polyethylene composite material prepared by the method for preparing a flame-retardant polyethylene composite material according to any one of claims 1 to 9.

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