A flame-retardant lead-boron modified polyethylene composite material and its preparation method

Abstract

This invention discloses a flame-retardant lead-boron modified polyethylene composite material and its preparation method. The flame-retardant lead-boron modified polyethylene composite material comprises the following components: 9–22.5 wt% ultra-high molecular weight polyethylene powder, 0.5–8 wt% boron carbide powder, 70–85 wt% lead powder, 5–15 wt% halogen-free flame retardant, 0.1–0.2 wt% antioxidant, 0.2–0.5 wt% coupling agent, 0.1–0.5 wt% lubricant, and 0.1–0.5 wt% dispersant. The flame-retardant lead-boron modified polyethylene composite material prepared in this invention has shielding performance comparable to conventional lead-boron polyethylene materials, while also possessing excellent flame-retardant and physicochemical properties. Its oxygen index is ≥28, and it achieves a V0 rating in the vertical burning test.

Description

Technical Field

[0001] This invention relates to the field of shielding materials technology. Specifically, it relates to a flame-retardant lead-boron modified polyethylene composite material and its preparation method. Background Technology

[0002] Lead-boron polyethylene (PPE) is a composite shielding material prepared by adding lead powder, boron carbide powder, and processing aids to polyethylene. PPE has a high hydrogen content, and hydrogen has a good attenuation ability for fast neutrons; boron carbide has a high boron content, and boron has a large thermal neutron absorption cross-section; lead has a good shielding effect against gamma radiation. Therefore, PPE simultaneously possesses excellent shielding effects against fast neutrons, thermal neutrons, and gamma radiation. Compared with traditional metallic materials, PPE helps simplify the shielding structure, reduce the weight and volume of the shield, and has been widely used in the shielding protection design of nuclear technology devices.

[0003] However, polyethylene, the base material of lead-boron polyethylene, is a flammable material, and its oxygen index is only 18, posing a safety hazard in engineering applications. Therefore, without reducing the shielding performance, flame-retardant modification of lead-boron polyethylene is a solution to improve its safety. However, the addition of a large amount of lead powder to lead-boron polyethylene significantly increases the difficulty of the process, and the improvement in flame-retardant performance is very limited. For example, invention patent CN200510116946.5, "A lead-boron polyethylene composite shielding material and its preparation method," mentions that adding 2 parts by weight of flame retardant, including magnesium hydroxide, aluminum hydroxide, and phosphorus pentoxide, achieves an oxygen index of 22, while the oxygen index of the material without flame retardant is only 19. Invention patent CN101033313A, "A Flame-Retardant Lead-Boron Polyethylene Composite Material," mentions the use of 2.8–3.8 parts by weight of a composite flame retardant, consisting of 10–20% zinc borate, 60–70% microencapsulated red phosphorus, and 10–20% phenolic resin. The flame-retardant performance meets the FV-1 requirements of GB4609-84. Invention patent CN118006018A, "A Novel High Flame-Retardant Polyethylene-Based Shielding Material," proposes adding lead powder, boron carbide powder, cerium oxide, and benzoyl peroxide to an ultra-high molecular weight polyethylene substrate, followed by twin-screw extrusion granulation. The resulting product has an oxygen index as high as 31, but no data on vertical combustion performance is provided. Furthermore, cerium oxide is a rare earth material, relatively expensive, and difficult to widely apply.

[0004] The three patents mentioned above achieve a certain degree of flame retardancy by adding a small amount of flame retardant, but their flame retardancy still cannot meet the needs of actual engineering. For example, flame retardant materials require an oxygen index greater than 28, and some engineering fields require materials to reach a flame-retardant level with an oxygen index greater than 32, while also meeting the V0 vertical burning performance requirement. The materials mentioned in the three inventions cannot meet these requirements; they either only specify the oxygen index or only the vertical burning performance. For flame retardant materials, simultaneously meeting both the oxygen index and vertical burning performance requirements is quite difficult to implement. Summary of the Invention

[0005] Therefore, the technical problem to be solved by the present invention is to provide a flame-retardant lead-boron modified polyethylene composite material and its preparation method. The obtained flame-retardant lead-boron modified polyethylene composite material has shielding performance comparable to that of conventional lead-boron polyethylene materials, and at the same time has excellent flame-retardant properties and physical and chemical properties. Its oxygen index is ≥28 and it reaches V0 level in the vertical burning method.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0007] A flame-retardant lead-boron modified polyethylene composite material is composed of the following components: 9-22.5 wt% ultra-high molecular weight polyethylene powder, 0.5-8 wt% boron carbide powder, 70-85 wt% lead powder, 5-15 wt% halogen-free flame retardant, 0.1-0.2 wt% antioxidant, 0.2-0.5 wt% coupling agent, 0.1-0.5 wt% lubricant, and 0.1-0.5 wt% dispersant.

[0008] The above-mentioned flame-retardant lead-boron modified polyethylene composite material has a boron carbide powder particle size of less than or equal to 100 μm.

[0009] The lead powder in the above-mentioned flame-retardant lead-boron modified polyethylene composite material has a particle size of 80-500 mesh.

[0010] The flame retardant in the above-mentioned lead-boron modified polyethylene composite material has a flame retardant particle size of 200-1000 mesh.

[0011] The antioxidant in the above-mentioned flame-retardant lead-boron modified polyethylene composite material is one or more of antioxidant 1010, antioxidant 7910, antioxidant FD958 and antioxidant FD658.

[0012] The aforementioned flame-retardant lead-boron modified polyethylene composite material uses phthalate coupling agents and / or silane coupling agents. Among them, phthalate coupling agents include NDZ201, LD101, and LD126, and silane coupling agents include KH550, KH560, and KH570.

[0013] The above-mentioned flame-retardant lead-boron modified polyethylene composite material uses calcium stearate and / or zinc stearate as lubricant and polyethylene wax or oxidized polyethylene wax as dispersant. Among them, polyethylene wax includes TW-F0042 and TW-F4001, etc., and oxidized polyethylene wax includes S8115 and S0816, etc., and the melting point of polyethylene wax is ≥132℃.

[0014] The aforementioned flame-retardant lead-boron modified polyethylene composite material uses ultra-high molecular weight polyethylene powder with a viscosity coefficient of 1000-4500 ml / g.

[0015] The above-mentioned flame-retardant lead-boron modified polyethylene composite material has a density of 3.0–5.0 g / cm³. 3 .

[0016] The preparation method of the above-mentioned flame-retardant lead-boron modified polyethylene composite material includes the following steps:

[0017] Step 1) Mixing: Weigh out the ultra-high molecular weight polyethylene powder, boron carbide powder, lead powder, flame retardant, antioxidant powder, coupling agent and lubricant and put them into a dry powder mixer to mix and obtain mixed powder. The speed is 20-60 r / min and the mixing time is 2-120 min.

[0018] Step 2) Mixing: Add the mixed powder obtained in step 1) into the rheometer chamber of the internal mixer and heat and stir for 10 to 300 seconds to obtain the mixed material. The temperature of the internal mixer is 160 to 190℃ and the speed is 10 to 40 r / min.

[0019] Step 3) Molding: After weighing the mixture obtained in Step 2), place it into a mold for pressing to obtain a flame-retardant lead-boron modified polyethylene composite material; the specific pressing operation is as follows:

[0020] Step 3-1) Pre-compress for 5-10 minutes, with a pre-compressing pressure of 3-5 MPa and a pre-compressing temperature of 130-150℃;

[0021] Step 3-2) Two-stage formal pressing: The pressing time of the first stage is 5-10 min, the pressure is 10 MPa, and the temperature is 150-170℃; the pressing time of the second stage is 10-20 min, the pressure is 15-20 MPa, and the temperature is 170-190℃.

[0022] Step 3-3) Cool the water to 50-60℃ and maintain the pressure at 18-20MPa.

[0023] The technical solution of the present invention achieves the following beneficial technical effects:

[0024] 1. It has good flame retardant properties, with an oxygen index reaching the flame-retardant level and a vertical burning V0 rating, which is significantly improved compared to traditional lead-boron polyethylene materials.

[0025] 2. Through the combined use of dispersants, lubricants, and flame retardants, as well as the coordination of the preparation process, the prepared shielding material has extremely excellent mechanical properties, which are significantly improved compared with traditional shielding materials.

[0026] 3. Through the combined use of coupling agents, dispersants, lubricants, and flame retardants, as well as reasonable preparation process flow and control parameters, the polyethylene substrate and the large amount of added lead powder additives are tightly bonded, which significantly reduces dust pollution during cutting and processing, greatly reduces the generation of lead dust, protects the physiological health of operators, and improves the environmental safety of the production environment. Attached Figure Description

[0027] Figure 1 Electron micrograph of a flame-retardant lead-boron modified polyethylene composite material. Detailed Implementation

[0028] Example 1

[0029] The flame-retardant lead-boron modified polyethylene composite material in this embodiment consists of 22 parts by weight of ultra-high molecular weight polyethylene powder MII I with a molecular weight of 3.5 million, 70 parts by weight of lead powder with a particle size of 200 mesh and a purity greater than or equal to 99.5 wt%, 1.0 part by weight of boron carbide powder with a particle size of 325 mesh, 6.4 parts by weight of intumescent phosphorus-nitrogen composite flame retardant FR8310, 0.1 parts by weight of antioxidant 7910, 0.1 parts by weight of calcium stearate CV500, 0.3 parts by weight of coupling agent LD-B, and 0.1 parts by weight of polyethylene wax S3816.

[0030] The flame-retardant lead-boron modified polyethylene composite material used in this embodiment is prepared through the following steps:

[0031] Step 1) Weigh out the ultra-high molecular weight polyethylene powder MII I, boron carbide powder, lead powder, flame retardant FR8310, antioxidant 7910, coupling agent LD-B, calcium stearate CV500 and polyethylene wax S3816, put them into a sealed container, start the powder mixing equipment, rotate at 50 r / min, mix for 60 min to obtain mixed powder;

[0032] Step 2) Set the internal mixer temperature to 180-190℃ and the speed to 25r / min. Pour the mixed powder obtained in Step 1) into the internal mixer and mix for 2 minutes to obtain the mixed material. During the mixing process, pay attention to temperature control to prevent the material from clumping due to excessive temperature.

[0033] Step 3) Weigh the mixture obtained in Step 2) and place it into the mold while it is still hot. Set the mold temperature to 165℃, pre-press 3-5 MPa for 5 minutes at 130℃; increase the pressure to 10 MPa for 10 minutes at 150℃; increase the pressure to 20 MPa and hold for 30 minutes at 165℃; then circulate cooling water to lower the temperature, maintaining the pressure at 18-20 MPa. Gradually increasing the pressure effectively removes any air bubbles that may be mixed into the material, promoting uniform material distribution; holding the pressure during cooling helps release stress during the cooling process, maintaining a smooth shape.

[0034] Step 4) After hot pressing for 10 minutes, cool the product to room temperature by passing cooling water through the mold.

[0035] Example 2

[0036] The flame-retardant lead-boron modified polyethylene composite material in this embodiment consists of 16.0 parts by weight of ultra-high molecular weight polyethylene powder with a molecular weight of 2.5 million, 70 parts by weight of lead powder with a particle size of 200 mesh and a purity greater than or equal to 99.5 wt%, 8.0 parts by weight of boron carbide powder with a particle size of 200 mesh, 5.6 parts by weight of intumescent phosphorus-nitrogen composite flame retardant FR8370A, 0.1 parts by weight of antioxidant 1010, 0.1 parts by weight of zinc stearate AV301, 0.1 parts by weight of coupling agent KH550, and 0.1 parts by weight of polyethylene wax S8115.

[0037] The flame-retardant lead-boron modified polyethylene composite material used in this embodiment is prepared through the following steps:

[0038] Step 1) Weigh out the ultra-high molecular weight polyethylene powder, boron carbide powder, lead powder, flame retardant FR8370, antioxidant 1010, zinc stearate AV301, coupling agent KH550 and polyethylene wax S8115, put them into a sealed container, start the powder mixing equipment, rotate at 50 r / min, mix for 90 min, change the rotation direction once in the middle, and mix the materials more evenly by changing the rotation direction of the mixing rollers.

[0039] Step 2) Set the internal mixer temperature to 185℃ and the speed to 25r / min. Pour the mixed powder into the internal mixer and mix for 2.5min. During the mixing process, pay attention to temperature control to prevent the material from clumping due to excessive temperature.

[0040] Step 3) Weigh the mixed lead-boron polyethylene mixture and place it into the mold while it is still hot. Set the mold temperature to 170℃, pre-press 3-5MPa for 5 minutes at 135℃; increase the pressure to 10MPa for 10 minutes at 150℃; increase the pressure to 20MPa and hold for 30 minutes at 170℃; cool with cooling water and maintain the pressure at 18-20MPa.

[0041] Step 4) After hot pressing for 10 minutes, cool the product to room temperature by passing cooling water through the mold.

[0042] Example 3

[0043] The flame-retardant lead-boron modified polyethylene composite material in this embodiment comprises 13.3 parts by weight of ultra-high molecular weight polyethylene with a molecular weight of 1.5 million, 77.3 parts by weight of lead powder with a particle size of 200 mesh and a purity greater than or equal to 99.5 wt%, 1.5 parts by weight of boron carbide powder with a particle size of 200 mesh, 7.3 parts by weight of intumescent phosphorus-nitrogen composite flame retardant FR-T305, 0.1 parts by weight of antioxidant 7910, 0.1 parts by weight of calcium stearate G130, 0.2 parts by weight of coupling agent LD122, and 0.2 parts by weight of polyethylene wax TW-F4002.

[0044] The flame-retardant lead-boron modified polyethylene composite material used in this embodiment is prepared through the following steps:

[0045] Step 1) Weigh out the ultra-high molecular weight polyethylene powder, boron carbide powder, lead powder, intumescent phosphorus-nitrogen composite flame retardant FR-T305, antioxidant 7910, calcium stearate G130, coupling agent LD122 and polyethylene wax TW-F4002, put them into a sealed container, start the powder mixing equipment, rotate at 40 r / min, and mix for 30 min to obtain a mixed powder.

[0046] Step 2) Set the internal mixer temperature to 160-190℃ and the speed to 25r / min. Pour the mixed powder obtained in Step 1) into the internal mixer and mix for 3 minutes to obtain the mixed material. During the mixing process, pay attention to temperature control to prevent the material from clumping due to excessive temperature.

[0047] Step 3) Weigh the mixture obtained in Step 2) and place it into the mold while it is still hot. Set the mold temperature to 160℃, pre-press 3-5MPa for 5 minutes at 135℃; increase the pressure to 10MPa for 10 minutes at 145℃; increase the pressure to 20MPa and hold for 30 minutes at 160℃; cool down with cooling water and maintain the pressure at 18-20MPa.

[0048] Step 4) After hot pressing for 10 minutes, cool the product to room temperature by passing cooling water through the mold.

[0049] Example 4

[0050] The flame-retardant lead-boron modified polyethylene composite material in this embodiment comprises 9.9 parts by weight of ultra-high molecular weight polyethylene with a molecular weight of 2 million, 80 parts by weight of lead powder with a particle size of 80 mesh and a purity greater than or equal to 99.5 wt%, 3.0 parts by weight of boron carbide powder with a particle size of 325 mesh, 7.0 parts by weight of intumescent phosphorus-nitrogen composite flame retardant FR8300, 0.1 parts by weight of antioxidant 1010, 0.1 parts by weight of coupling agent LD123, 0.1 parts by weight of zinc stearate AV350S, and 0.1 parts by weight of oxidized polyethylene wax S0816.

[0051] The flame-retardant lead-boron modified polyethylene composite material used in this embodiment is prepared through the following steps:

[0052] Step 1) Weigh out the ultra-high molecular weight polyethylene powder, boron carbide powder, lead powder, flame retardant FR8300, antioxidant 1010, coupling agent LD123, zinc stearate AV350S and oxidized polyethylene wax dispersant S0816, put them into a sealed container, start the powder mixing equipment, rotate at 40 r / min, and mix for 50 min to obtain a mixed powder.

[0053] Step 2) Set the internal mixer temperature to 180℃ and the rotation speed to 30r / min. Pour the mixed powder obtained in Step 1) into the internal mixer and mix for 25 minutes to obtain the mixed material. During the mixing process, pay attention to controlling the temperature to prevent the material from clumping due to excessive temperature.

[0054] Step 3) Weigh the mixture obtained in Step 2) and place it into the mold while it is still hot. Set the mold temperature to 190℃, pre-press 3-5MPa for 5 minutes at 150℃; increase the pressure to 10MPa for 10 minutes at 170℃; increase the pressure to 20MPa and hold for 30 minutes at 190℃; cool down with cooling water and maintain the pressure at 18-20MPa.

[0055] Step 4) After hot pressing for 10 minutes, cool the product to room temperature by passing cooling water through the mold.

[0056] Example 5

[0057] The flame-retardant lead-boron modified polyethylene composite material in this embodiment consists of 9.3 parts by weight of ultra-high molecular weight polyethylene powder MII I with a molecular weight of 3.5 million, 85.0 parts by weight of lead powder with a particle size of 260 mesh and a purity greater than or equal to 99.5 wt%, 0.5 parts by weight of boron carbide powder with a particle size of 325 mesh, 5.0 parts by weight of intumescent phosphorus-nitrogen flame retardant FR8310, 0.1 parts by weight of antioxidant 7910, 0.2 parts by weight of coupling agent LD560, 0.1 parts by weight of calcium stearate CV550, and 0.2 parts by weight of polyethylene wax TW-F0041.

[0058] The flame-retardant lead-boron modified polyethylene composite material used in this embodiment is prepared through the following steps:

[0059] Step 1) Weigh out the ultra-high molecular weight polyethylene powder, boron carbide powder, lead powder, flame retardant FR8310, antioxidant 7910, coupling agent LD560, calcium stearate CV550 and polyethylene wax TW-F0041, put them into a sealed container, start the powder mixing equipment, rotate at 50 r / min, mix for 60 min, and change the rotation direction once in the middle.

[0060] Step 2) Set the internal mixer temperature to 190℃ and the speed to 25r / min. Pour the mixed powder into the internal mixer and mix for 2.5min. During the mixing process, pay attention to temperature control to prevent the material from clumping due to excessive temperature.

[0061] Step 3) Weigh the mixed lead-boron polyethylene mixture and place it into the mold while it is still hot. Set the mold temperature to 170℃, pre-press 3-5MPa for 5 minutes at 140℃; increase the pressure to 10MPa for 10 minutes at 155℃; increase the pressure to 20MPa and hold for 30 minutes at 170℃; cool with cooling water and maintain the pressure at 18-20MPa.

[0062] Step 4) After hot pressing for 10 minutes, cool the product to room temperature by passing cooling water through the mold.

[0063] The high-strength lead-boron polyethylene-based shielding material prepared in Example 3 of this invention is shown in the ×500 electron microscope image. Figure 1 As shown.

[0064] The performance of the flame-retardant lead-boron modified polyethylene composite materials prepared in Examples 1 to 5 and the lead-boron polyethylene PB202 mentioned in the literature "High-efficiency shielding material lead-boron polyethylene" were tested, and the test results are shown in Table 1.

[0065] Table 1 Performance test results of flame-retardant lead-boron modified polyethylene composite material and PB202

[0066] Sample 1 Sample 2 Sample 3 Sample 4 Sample 5 PB202 <![CDATA[Density (g / cm 3 )]]> 3.00 3.40 4.01 4.56 5.01 3.42 Tensile strength (MPa) 43.2 45.2 44.4 42.2 47.3 12.6 Bending strength (MPa) 39.7 40.5 28.1 34.2 42.6 19.8 Oxygen Index (LOI) 28.2 28.3 28.0 28.5 28.0 18 Vertical combustion performance V0 V0 V0 V0 V0 ＜V2 Neutron shielding coefficient (4cm) 3.75 3.61 3.55 3.41 3.42 3.58 <![CDATA[ 60 Coγ shielding coefficient (4cm) 1.98 2.22 2.61 2.97 3.23 2.23

[0067] Among them, Samples 1 to 5 are samples prepared from the flame-retardant lead-boron modified polyethylene composite materials obtained in Examples 1 to 5, respectively. Compared with the lead-boron polyethylene PB202 mentioned in the literature "High-Efficiency Shielding Material Lead-Boron Polyethylene", under similar density conditions, the oxygen index of the flame-retardant lead-boron modified polyethylene composite material of the present invention is significantly improved, reaching the flame-retardant level, and the vertical burning performance reaches the V0 level, while the mechanical strength is significantly improved.

[0068] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of the claims of this patent application.

Claims

1. A flame-retardant lead-boron modified polyethylene composite material, characterized in that, The composite material is composed of the following components: 9–22.5 wt% ultra-high molecular weight polyethylene powder, 0.5–8 wt% boron carbide powder, 70–85 wt% lead powder, 5–15 wt% halogen-free flame retardant, 0.1–0.2 wt% antioxidant, 0.2–0.5 wt% coupling agent, 0.1–0.5 wt% lubricant, and 0.1–0.5 wt% dispersant; wherein the boron carbide powder has a particle size of less than or equal to 100 μm, the lead powder has a particle size of 80–500 mesh, and the lead powder purity is greater than or equal to 99.5 wt%; the halogen-free flame retardant is composed of a smoke suppressant and a phosphorus-nitrogen intumescent composite flame retardant and / or a phosphorus-nitrogen composite organic flame retardant, and the halogen-free flame retardant has a particle size of 200–1000 mesh; the flame-retardant lead-boron modified polyethylene composite material is prepared through the following steps: Step 1) Mixing: Weigh out the ultra-high molecular weight polyethylene powder, boron carbide powder, lead powder, halogen-free flame retardant, antioxidant, coupling agent, lubricant and dispersant and put them into a dry powder mixer to mix and obtain mixed powder. The speed is 20-60 r / min and the mixing time is 2-120 min. Step 2) Mixing: Add the mixed powder obtained in step 1) into the rheometer chamber of the internal mixer and heat and stir for 10 to 300 seconds to obtain the mixed material. The temperature of the internal mixer is 160 to 190℃ and the speed is 10 to 40 r / min. Step 3) Molding: After weighing the mixture obtained in Step 2), place it into a mold for pressing to obtain a flame-retardant lead-boron modified polyethylene composite material; the specific pressing operation is as follows: Step 3-1) Pre-compress for 5-10 minutes, with a pre-compressing pressure of 3-5 MPa and a pre-compressing temperature of 130-150℃; Step 3-2) Two-stage formal pressing: The pressing time of the first stage is 5-10 min, the pressure is 10 MPa, and the temperature is 150-170℃; the pressing time of the second stage is 10-20 min, the pressure is 15-20 MPa, and the temperature is 170-190℃. Step 3-3) Cool the water to 50-60℃ and maintain the pressure at 18-20MPa.

2. The flame-retardant lead-boron modified polyethylene composite material according to claim 1, characterized in that, The antioxidant is one or more of antioxidant 1010, antioxidant 7910, antioxidant FD958 and antioxidant FD658.

3. The flame-retardant lead-boron modified polyethylene composite material according to claim 1, characterized in that, The coupling agent is a titanate coupling agent or a silane coupling agent.

4. The flame-retardant lead-boron modified polyethylene composite material according to claim 1, characterized in that, The lubricant is calcium stearate and / or zinc stearate, and the dispersant is polyethylene wax or oxidized polyethylene wax.

5. The flame-retardant lead-boron modified polyethylene composite material according to claim 1, characterized in that, Ultra-high molecular weight polyethylene powder is made from ultra-high molecular weight polyethylene with a viscosity coefficient of 1000-4500 ml / g.

6. The flame-retardant lead-boron modified polyethylene composite material according to claim 1, characterized in that, The density of flame-retardant lead-boron modified polyethylene composite material is 3.0–5.0 g / cm³. 3 .

7. The method for preparing the flame-retardant lead-boron modified polyethylene composite material according to claim 1, characterized in that, Includes the following steps: Step 1) Mixing: Weigh out the ultra-high molecular weight polyethylene powder, boron carbide powder, lead powder, halogen-free flame retardant, antioxidant, coupling agent, lubricant and dispersant and put them into a dry powder mixer to mix and obtain mixed powder. The speed is 20-60 r / min and the mixing time is 2-120 min. Step 2) Mixing: Add the mixed powder obtained in step 1) into the rheometer chamber of the internal mixer and heat and stir for 10 to 300 seconds to obtain the mixed material. The temperature of the internal mixer is 160 to 190℃ and the speed is 10 to 40 r / min. Step 3) Molding: After weighing the mixture obtained in Step 2), place it into a mold for pressing to obtain a flame-retardant lead-boron modified polyethylene composite material; the specific pressing operation is as follows: Step 3-1) Pre-compress for 5-10 minutes, with a pre-compressing pressure of 3-5 MPa and a pre-compressing temperature of 130-150℃; Step 3-2) Two-stage formal pressing: The pressing time of the first stage is 5-10 min, the pressure is 10 MPa, and the temperature is 150-170℃; the pressing time of the second stage is 10-20 min, the pressure is 15-20 MPa, and the temperature is 170-190℃. Step 3-3) Cool the water to 50-60℃ and maintain the pressure at 18-20 MPa.

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