Flame-retardant heat-insulating high-elasticity chemically-crosslinked polyethylene high-foaming material and preparation method thereof

Abstract

The invention relates to the field of polyethylene materials, in particular to a flame-retardant heat-insulating high-elasticity chemically-crosslinked polyethylene high-foaming material and a preparation method thereof. The flame-retardant heat-insulating high-elasticity chemical crosslinked polyethylene high-foaming material comprises the following raw materials in parts by weight: 80-90 parts of low-density polyethylene, 1-3 parts of a crosslinking agent, 15-20 parts of a foaming agent and 15-20 parts of a flame retardant, the preparation method of the flame retardant comprises the following steps: immersing expanded perlite in a dimethylformamide solution of 2, 6-dichlorobenzenesulfonyl amino-acetic acid, and carrying out a reaction to obtain modified expanded perlite; mixing the muscovite dispersion liquid, the modified expanded perlite and water, and performing vacuum freeze drying and calcination to obtain composite powder; and mixing the composite powder, 3, 4-dihydroxy benzaldehyde and ethanol, and reacting to obtain the flame retardant. The flame-retardant heat-insulating high-elasticity chemical crosslinked polyethylene high-foaming material has excellent flame-retardant property, good heat-insulating effect and high elasticity.

Description

Technical Field

[0001] The present invention relates to the field of polyethylene materials, in particular to a flame-retardant and heat-insulating high-elasticity chemically cross-linked polyethylene high-foam material and a preparation method thereof. Background Art

[0002] In modern industrial production and daily life, there is a growing demand for flame-retardant and thermal-insulating polymer materials. This is particularly true in key areas such as building insulation, automotive interiors, electronics, and aerospace, where the application of high-performance flame-retardant and thermal-insulating materials is crucial. Traditional polymer materials, such as polyethylene, pose serious fire safety risks due to their flammability, rapid heat release rate during combustion, and the generation of large amounts of toxic fumes, limiting their widespread application.

[0003] Currently, common flame retardant and thermal insulation methods mainly include halogen-added flame retardants, inorganic flame retardants, and the construction of thermal insulation layers. However, halogen-based flame retardants release large amounts of toxic and harmful gases during combustion, posing a serious threat to the environment and human health. Furthermore, with increasingly stringent environmental regulations, their application is greatly restricted. Inorganic flame retardants such as aluminum hydroxide and magnesium hydroxide, while having a certain flame retardant effect and being environmentally friendly, significantly reduce the mechanical and processing properties of the material when added in large quantities, making it difficult to meet the requirements of high-elasticity and high-strength materials. The simple construction of thermal insulation layers can often only delay heat transfer to a certain extent, but cannot effectively prevent material combustion. Furthermore, under complex environmental conditions, the stability and reliability of the thermal insulation layer are difficult to guarantee.

[0004] Therefore, it is urgent to develop a chemically cross-linked polyethylene high foam material with excellent flame retardant properties, good thermal insulation effect and high elasticity to fill the gap in existing technology in this field and meet the market's urgent demand for high-performance flame retardant and thermal insulation materials. Summary of the Invention

[0005] In view of this, the present invention is dedicated to providing a flame retardant and heat-insulating high-elasticity chemically cross-linked polyethylene high-foam material and a preparation method thereof, so as to solve the problem of poor flame retardancy of polypropylene materials in the prior art.

[0006] In order to solve the above technical problems, this application is implemented as follows: The present invention provides a flame-retardant and heat-insulating high-elasticity chemically cross-linked polyethylene high-foam material, which is characterized by comprising the following raw materials in parts by weight: 80-90 parts of low-density polyethylene, 1-3 parts of cross-linking agent, 15-20 parts of foaming agent and 15-20 parts of flame retardant; The preparation method of the flame retardant comprises the following steps: (1) The expanded perlite is placed in an ethanol solution of a silane coupling agent for dispersion treatment to obtain treated expanded perlite; the treated expanded perlite is immersed in a dimethylformamide solution of 2,6-dichlorobenzenesulfonylamino-acetic acid to react to obtain modified expanded perlite; (2) mixing and dispersing muscovite and an aqueous solution of tetrabutylammonium hydroxide, reacting to obtain an exfoliated muscovite dispersion; mixing the muscovite dispersion, modified expanded perlite, and water, adjusting the pH to acidic, and performing vacuum freeze drying and calcining to obtain a composite powder; (3) The composite powder, 3,4-dihydroxybenzaldehyde and ethanol are mixed, the pH value is adjusted to acidic, and a first reaction is carried out. After the first reaction is completed, the temperature is raised to a second reaction temperature, a catalyst is added, and a second reaction is carried out to obtain a flame retardant.

[0007] Preferably, in the flame-retardant and heat-insulating high-elasticity chemically cross-linked polyethylene high-foam material, in step (1), the concentration of the ethanol solution of the silane coupling agent is 3-5wt%; In step (1), the silane coupling agent includes KH550; In step (1), the usage ratio of the expanded perlite and the ethanol solution of the silane coupling agent is 10-30 g: 50-200 mL; In step (1), the concentration of the dimethylformamide solution of 2,6-dichlorobenzenesulfonylamino-acetic acid is 5-10 wt %; In step (1), the usage ratio of the expanded perlite and the dimethylformamide solution of 2,6-dichlorobenzenesulfonylamino-acetic acid is 10-20 g: 50-200 mL.

[0008] Preferably, in the above-mentioned flame-retardant and heat-insulating high-elasticity chemically cross-linked polyethylene high-foam material, in step (1), the dispersion treatment time is 30 to 40 minutes; In step (1), the immersion conditions are: pressure of -0.1 to -0.05 MPa, temperature of 10 to 30°C, and time of 1 to 2 hours; In step (1), the reaction process is: reacting at 50-60°C for 4-5 hours, and then reacting at 110-120°C for 2-3 hours.

[0009] Preferably, in the flame-retardant and heat-insulating high-elasticity chemically cross-linked polyethylene high-foam material, in step (2), the concentration of the aqueous solution of tetrabutylammonium hydroxide is 5-10wt%; In step (2), the ratio of the muscovite mica to the aqueous solution of tetrabutylammonium hydroxide is 5-10 g: 150-300 mL; In step (2), the mass ratio of the modified expanded perlite to the muscovite is 15-30:5-10; In step (2), the usage ratio of the modified expanded perlite to the water is 15-30 g: 300-500 mL; In step (2), the target pH value is 5-6.

[0010] Preferably, in the above-mentioned flame-retardant and heat-insulating high-elasticity chemically cross-linked polyethylene high-foam material, in step (2), the reaction temperature is 70-80° C., and the reaction time is 24-48 hours; In step (2), the vacuum freeze-drying time is 24 to 48 hours; In step (2), the calcination conditions are: atmosphere is inert gas, temperature is 400-500°C, and time is 1-2h.

[0011] Preferably, in the above-mentioned flame-retardant and heat-insulating high-elasticity chemically cross-linked polyethylene high-foam material, in step (3), the mass ratio of the composite powder to the 3,4-dihydroxybenzaldehyde is 10-20:3-8; In step (3), the ratio of the composite powder to the ethanol is 10-20 g: 100-300 mL; In step (3), the target pH value is 5-6; In step (3), the mass ratio of the composite powder to the catalyst is 10-20:1-3; In step (3), the catalyst is p-toluenesulfonic acid.

[0012] Preferably, in the above-mentioned flame-retardant and heat-insulating high-elasticity chemically cross-linked polyethylene high-foam material, in step (3), the temperature of the first reaction is 50-60° C., and the time of the first reaction is 3-4 hours; In step (3), the temperature of the second reaction is 100-120° C., and the time of the second reaction is 1-3 hours.

[0013] In the preparation process of the flame retardant, 2,6-dichlorobenzenesulfonylamino-acetic acid is infiltrated into the pores of perlite under vacuum conditions, and stable chemical bonds are ensured through distribution reactions, thereby achieving intercalation modification of the expanded perlite and increasing the spacing between the expanded perlite; the chlorine element captures free radicals in the gas phase, inhibiting the combustion chain reaction; after the muscovite is dispersed and exfoliated, the specific surface area is increased; the muscovite surface is positively charged, and the modified perlite is negatively charged, forming a "perlite-muscovite" composite skeleton through electrostatic adsorption; vacuum freeze-drying retains the pore structure, and inert atmosphere calcination removes residual organic matter and enhances the rigidity of the skeleton, thereby reflecting thermal radiation and extending the heat conduction path; finally, under acidic conditions (pH = 5-6), the phenolic hydroxyl groups of 3,4-dihydroxybenzaldehyde are promoted to condense with the hydroxyl groups on the surface of the composite powder to form a "core-shell" structure (the composite powder is the core and the phenolic condensate is the shell), thereby improving the quality of the carbon layer and the flame retardant efficiency.

[0014] Preferably, in the above-mentioned flame-retardant and heat-insulating high-elasticity chemically cross-linked polyethylene high-foam material, the cross-linking agent includes dicumyl peroxide or dibenzoyl peroxide; The blowing agent includes azodicarbonamide.

[0015] The present invention also provides a method for preparing a flame-retardant and heat-insulating high-elasticity chemically cross-linked polyethylene high-foam material, comprising the following steps: Low-density polyethylene, a cross-linking agent and a flame retardant are mixed, subjected to a first melt extrusion, and then mixed with a foaming agent and subjected to a second melt extrusion to obtain a flame-retardant and heat-insulating high-elasticity chemically cross-linked polyethylene high-foaming material.

[0016] Preferably, in the above-mentioned method for preparing a flame-retardant and heat-insulating high-elasticity chemically cross-linked polyethylene high-foam material, the temperature of the first melt extrusion is 120-140°C; The temperature of the second melt extrusion is 110-130°C.

[0017] Through the above technical solution, the beneficial technical effects of the present invention are: The flame-retardant, heat-insulating, highly elastic chemically cross-linked polyethylene foam material provided by this invention achieves flame retardancy, heat insulation, and high elasticity through the synergistic effect of multiple components and a hierarchical structural design. First, low-density polyethylene (LDPE) serves as the base material. Chemical cross-linking is initiated by a cross-linking agent such as dicumyl peroxide to form a three-dimensional network structure, imparting high elasticity and thermal stability. The azodicarbonamide foaming agent decomposes and produces gas during the melt extrusion process, forming a uniform closed-cell structure that reduces density while maintaining resilience. In the flame retardant, expanded perlite is modified with the silane coupling agent KH550 and then intercalated with 2,6-dichlorobenzenesulfonylamino-acetic acid. This intercalation increases the spacing between the expanded perlite, making its internal structure more porous and porous, providing more space for heat absorption and dispersion. Furthermore, the sulfonyl and amino groups catalyze carbonization during combustion, releasing nitrogen-based flame-retardant gases. Muscovite is exfoliated into nanosheets using tetrabutylammonium hydroxide and then composited with the modified perlite. After acidic self-assembly and calcination, a hierarchical porous structure is formed, which reflects thermal radiation and extends the heat conduction path. 3,4-Dihydroxybenzaldehyde condenses with the surface of the composite powder via its phenolic hydroxyl groups. The introduced aromatic ring structure promotes the formation of a dense carbon layer at high temperatures. p-Toluenesulfonic acid further catalyzes the polycondensation reaction, strengthening the crosslinked network and enhancing the continuity of the carbon layer. The physical barrier effect of the perlite-muscovite combination slows thermal diffusion, while the crosslinked network maintains the integrity of the foamed structure. DETAILED DESCRIPTION

[0018] The present invention discloses a flame retardant and heat-insulating high-elasticity chemically cross-linked polyethylene high-foam material and a preparation method thereof. Those skilled in the art can refer to the content of this article and appropriately improve the process parameters to achieve the desired effect. It should be noted in particular that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included in the present invention. The methods and applications of the present invention have been described through preferred embodiments, and relevant personnel can obviously modify or appropriately change and combine the methods and applications described herein without departing from the content, spirit and scope of the present invention to implement and apply the technology of the present invention.

[0019] The present invention is further described in detail below by way of examples. The raw materials used in the examples can all be obtained through commercial sources.

[0020] Example 1: A flame-retardant, heat-insulating, highly elastic chemically cross-linked polyethylene foam material comprising the following raw materials in parts by weight: 90 parts of low-density polyethylene, 3 parts of cross-linking agent diisopropylbenzene oxide, 20 parts of foaming agent azodicarbonamide and 20 parts of flame retardant; The method for preparing the flame retardant comprises the following steps: (1) 30 g of expanded perlite was placed in 150 mL of 5 wt% ethanol solution of silane coupling agent KH550 and dispersed for 40 min to obtain the treated expanded perlite; the treated expanded perlite was immersed in 100 mL of 10 wt% 2,6-dichlorobenzenesulfonylamino-acetic acid dimethylformamide solution under vacuum conditions of -0.1 MPa and 20°C for 2 h, and after the immersion, the solution was reacted at 60°C for 4 h and then at 110°C for 2 h to obtain the modified expanded perlite; (2) 8 g of muscovite and 200 mL of an 8 wt% aqueous solution of tetrabutylammonium hydroxide were mixed and dispersed, and the mixture was reacted at 80 °C for 24 h to obtain an exfoliated muscovite dispersion; 25 g of modified expanded perlite and 500 mL of water were added to the muscovite dispersion, and then 0.5% glacial acetic acid was added to adjust the pH to 6. The mixture was freeze-dried in a vacuum for 48 h, and then calcined at 500 °C for 2 h under a nitrogen atmosphere to obtain a composite powder; (3) 20 g of composite powder, 8 g of 3,4-dihydroxybenzaldehyde and 300 mL of ethanol were mixed, 0.5% glacial acetic acid was added to adjust the pH value to 5, and the mixture was reacted at 60 °C for 4 h. After the reaction, the temperature was raised to 120 °C, 3 g of catalyst p-toluenesulfonic acid was added, and the mixture was reacted at 120 °C for 3 h. After the reaction, the obtained product was washed and dried to obtain a flame retardant.

[0021] The preparation method of a flame-retardant, heat-insulating, highly elastic chemically cross-linked polyethylene foam material comprises the following steps: Low-density polyethylene, a cross-linking agent and a flame retardant are mixed, melt-extruded at 120° C., and then mixed with a foaming agent and melt-extruded at 110° C. to obtain a flame-retardant and heat-insulating high-elasticity chemically cross-linked polyethylene high-foam material.

[0022] Example 2: A flame-retardant, heat-insulating, highly elastic chemically cross-linked polyethylene foam material comprising the following raw materials in parts by weight: 90 parts of low-density polyethylene, 3 parts of cross-linking agent diisopropylbenzene oxide, 15 parts of foaming agent azodicarbonamide and 15 parts of flame retardant; The method for preparing the flame retardant comprises the following steps: (1) 20 g of expanded perlite was placed in 50-200 mL of an ethanol solution of a silane coupling agent KH550 with a concentration of 3-5 wt% and dispersed for 30-40 min to obtain the treated expanded perlite; the treated expanded perlite was immersed in 50-200 mL of a dimethylformamide solution of 2,6-dichlorobenzenesulfonylamino-acetic acid with a concentration of 5-10 wt% under vacuum conditions of -0.1 MPa and 20°C for 1-2 h, and after the immersion, the solution was reacted at 50-60°C for 4-5 h, and then at 110-120°C for 2-3 h to obtain the modified expanded perlite; (2) 8 g of muscovite and 300 mL of a 10 wt% aqueous solution of tetrabutylammonium hydroxide were mixed and dispersed, and the mixture was reacted at 80 °C for 24 to 48 h to obtain an exfoliated muscovite dispersion; 15 g of modified expanded perlite and 500 mL of water were added to the muscovite dispersion, and then 0.5% glacial acetic acid was added to adjust the pH to 6. The mixture was vacuum freeze-dried for 48 h, and then calcined at 500 °C for 2 h under a nitrogen atmosphere to obtain a composite powder; (3) 10 g of composite powder, 5 g of 3,4-dihydroxybenzaldehyde and 200 mL of ethanol were mixed, 0.5% glacial acetic acid was added to adjust the pH value to 5, and the mixture was reacted at 60 °C for 4 h. After the reaction, the temperature was raised to 120 °C, 3 g of catalyst p-toluenesulfonic acid was added, and the mixture was reacted at 120 °C for 3 h. After the reaction, the obtained product was washed and dried to obtain a flame retardant.

[0023] The preparation method of a flame-retardant, heat-insulating, highly elastic chemically cross-linked polyethylene foam material comprises the following steps: Low-density polyethylene, a cross-linking agent and a flame retardant are mixed, melt-extruded at 120° C., and then mixed with a foaming agent and melt-extruded at 110° C. to obtain a flame-retardant and heat-insulating high-elasticity chemically cross-linked polyethylene high-foam material.

[0024] Example 3: A flame-retardant, heat-insulating, highly elastic chemically cross-linked polyethylene foam material comprising the following raw materials in parts by weight: 80 parts of low-density polyethylene, 2 parts of cross-linking agent diisopropylbenzene oxide, 20 parts of foaming agent azodicarbonamide and 15 parts of flame retardant; The method for preparing the flame retardant comprises the following steps: (1) 20 g of expanded perlite was placed in 200 mL of 5 wt% ethanol solution of silane coupling agent KH550 and dispersed for 40 min to obtain treated expanded perlite; the treated expanded perlite was immersed in 200 mL of 10 wt% 2,6-dichlorobenzenesulfonylamino-acetic acid dimethylformamide solution under vacuum conditions of -0.1 MPa and 20°C for 2 h, and after the immersion, the mixture was reacted at 60°C for 4 h and then at 110°C for 2 h to obtain modified expanded perlite; (2) 5 g of muscovite and 150 mL of a 10 wt% aqueous solution of tetrabutylammonium hydroxide were mixed and dispersed, and the mixture was reacted at 80 ° C for 24 h to obtain an exfoliated muscovite dispersion; 15 g of modified expanded perlite and 300 mL of water were added to the muscovite dispersion, and then 0.5% glacial acetic acid was added to adjust the pH to 6. The mixture was vacuum freeze-dried for 24 h, and then calcined at 400 ° C for 1 h under a nitrogen atmosphere to obtain a composite powder; (3) 10 g of the composite powder, 3 g of 3,4-dihydroxybenzaldehyde and 100 mL of ethanol were mixed, 0.5% glacial acetic acid was added to adjust the pH value to 5, and the mixture was reacted at 60 °C for 4 h. After the reaction, the temperature was raised to 120 °C, 1 g of catalyst p-toluenesulfonic acid was added, and the mixture was reacted at 120 °C for 3 h. After the reaction, the obtained product was washed and dried to obtain a flame retardant.

[0025] The preparation method of a flame-retardant, heat-insulating, highly elastic chemically cross-linked polyethylene foam material comprises the following steps: Low-density polyethylene, a cross-linking agent and a flame retardant are mixed, melt-extruded at 120° C., and then mixed with a foaming agent and melt-extruded at 130° C. to obtain a flame-retardant and heat-insulating high-elasticity chemically cross-linked polyethylene high-foam material.

[0026] Comparative Example 1, flame retardant and heat-insulating high-elasticity chemically cross-linked polyethylene high-foam material, is different from Example 1 in that: The preparation method of the flame retardant comprises the following steps: (1) 30 g of expanded perlite was placed in 150 mL of 5 wt% ethanol solution of silane coupling agent KH550 and dispersed for 40 min to obtain the treated expanded perlite; the treated expanded perlite was immersed in 100 mL of 10 wt% 2,6-dichlorobenzenesulfonylamino-acetic acid dimethylformamide solution under vacuum conditions of -0.1 MPa and 20°C for 2 h, and after the immersion, the solution was reacted at 60°C for 4 h and then at 110°C for 2 h to obtain the modified expanded perlite; (2) 20 g of modified expanded perlite, 8 g of 3,4-dihydroxybenzaldehyde and 300 mL of ethanol were mixed, 0.5% glacial acetic acid was added to adjust the pH value to 5, and the mixture was reacted at 60 °C for 4 h. After the reaction, the mixture was heated to 120 °C and 3 g of catalyst p-toluenesulfonic acid was added, and the mixture was reacted at 120 °C for 3 h. After the reaction, the product was washed and dried to obtain a flame retardant.

[0027] The rest are the same as in Example 1.

[0028] Comparative Example 2, flame retardant and heat-insulating high-elasticity chemically cross-linked polyethylene high-foam material, differs from Example 1 in that: (1) 8 g of muscovite and 200 mL of an 8 wt% aqueous solution of tetrabutylammonium hydroxide were mixed and dispersed, and the mixture was reacted at 80 °C for 24 h to obtain an exfoliated muscovite dispersion; 25 g of expanded perlite and 500 mL of water were added to the muscovite dispersion, and then 0.5% glacial acetic acid was added to adjust the pH to 6. The mixture was freeze-dried in a vacuum for 48 h, and then calcined at 500 °C for 2 h under a nitrogen atmosphere to obtain a composite powder; (2) 20 g of composite powder, 8 g of 3,4-dihydroxybenzaldehyde and 300 mL of ethanol were mixed, 0.5% glacial acetic acid was added to adjust the pH value to 5, and the mixture was reacted at 60 °C for 4 h. After the reaction, the temperature was raised to 120 °C, 3 g of catalyst p-toluenesulfonic acid was added, and the mixture was reacted at 120 °C for 3 h. After the reaction, the obtained product was washed and dried to obtain a flame retardant.

[0029] The rest are the same as in Example 1.

[0030] Comparative Example 3, flame retardant and heat-insulating high-elasticity chemically cross-linked polyethylene high-foam material, differs from Example 1 in that: (1) 30 g of expanded perlite was placed in 150 mL of 5 wt% ethanol solution of silane coupling agent KH550 and dispersed for 40 min to obtain the treated expanded perlite; the treated expanded perlite was immersed in 100 mL of 10 wt% 2,6-dichlorobenzenesulfonylamino-acetic acid dimethylformamide solution under vacuum conditions of -0.1 MPa and 20°C for 2 h, and after the immersion, the solution was reacted at 60°C for 4 h and then at 110°C for 2 h to obtain the modified expanded perlite; (2) 8 g of muscovite and 200 mL of an 8 wt% aqueous solution of tetrabutylammonium hydroxide were mixed and dispersed, and the mixture was reacted at 80 °C for 24 h to obtain an exfoliated muscovite dispersion. 25 g of modified expanded perlite and 500 mL of water were added to the muscovite dispersion, and then 0.5% glacial acetic acid was added to adjust the pH to 6. The mixture was freeze-dried in vacuum for 48 h, and then calcined at 500 °C for 2 h in a nitrogen atmosphere to obtain a flame retardant.

[0031] The rest are the same as in Example 1.

[0032] Test Case (1) Tensile strength and elongation at break: tested in accordance with GB / T1040.1-2018 standard, with a tensile rate of 50 mm / min; (2) Thermal conductivity: Tested in accordance with ASTM D5470; (3) Flame retardant properties (limiting oxygen index): According to the GB / T2406.2-2009 standard test, the limiting oxygen index of the sample was measured using an oxygen index meter. The sample size was 100 mm × 6.5 mm × 3.2 mm. The test results are shown in Table 1.

[0033] Table 1 .

[0034] As can be seen from Table 1, the flame retardant and mechanical properties of the material prepared in the embodiment of the present invention are better than those of the comparative example, and it has higher tensile strength, elongation at break, limiting oxygen index and lower thermal conductivity. It has excellent flame retardant and heat insulation effects and good mechanical properties.

[0035] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. Flame retardant and heat-insulating high-elasticity chemically cross-linked polyethylene high foam material, characterized by: The invention comprises the following raw materials in parts by weight: 80-90 parts of low-density polyethylene, 1-3 parts of cross-linking agent, 15-20 parts of foaming agent and 15-20 parts of flame retardant; The preparation method of the flame retardant comprises the following steps: (1) The expanded perlite is placed in an ethanol solution of a silane coupling agent for dispersion treatment to obtain treated expanded perlite; the treated expanded perlite is immersed in a dimethylformamide solution of 2,6-dichlorobenzenesulfonylamino-acetic acid to react to obtain modified expanded perlite; (2) mixing and dispersing muscovite and an aqueous solution of tetrabutylammonium hydroxide, reacting to obtain an exfoliated muscovite dispersion; mixing the muscovite dispersion, modified expanded perlite, and water, adjusting the pH to acidic, and performing vacuum freeze drying and calcining to obtain a composite powder; (3) The composite powder, 3,4-dihydroxybenzaldehyde and ethanol are mixed, the pH value is adjusted to acidic, and a first reaction is carried out. After the first reaction is completed, the temperature is raised to a second reaction temperature, a catalyst is added, and a second reaction is carried out to obtain a flame retardant.

2. The flame retardant and heat insulating high elastic chemical cross-linked polyethylene high foam material according to claim 1, characterized in that: In step (1), the concentration of the silane coupling agent ethanol solution is 3-5 wt %; In step (1), the silane coupling agent includes KH550; In step (1), the usage ratio of the expanded perlite and the ethanol solution of the silane coupling agent is 10-30 g: 50-200 mL; In step (1), the concentration of the dimethylformamide solution of 2,6-dichlorobenzenesulfonylamino-acetic acid is 5-10 wt %; In step (1), the usage ratio of the expanded perlite and the dimethylformamide solution of 2,6-dichlorobenzenesulfonylamino-acetic acid is 10-20 g: 50-200 mL.

3. The flame retardant and heat insulating high elastic chemical cross-linked polyethylene high foam material according to claim 1, characterized in that: In step (1), the dispersion treatment time is 30 to 40 minutes; In step (1), the immersion conditions are: pressure of -0.1 to -0.05 MPa, temperature of 10 to 30°C, and time of 1 to 2 hours; In step (1), the reaction process is: reacting at 50-60°C for 4-5 hours, and then reacting at 110-120°C for 2-3 hours.

4. The flame retardant and heat insulating high elastic chemical cross-linked polyethylene high foam material according to claim 1, characterized in that: In step (2), the concentration of the aqueous solution of tetrabutylammonium hydroxide is 5-10 wt %; In step (2), the ratio of the muscovite mica to the aqueous solution of tetrabutylammonium hydroxide is 5-10 g: 150-300 mL; In step (2), the mass ratio of the modified expanded perlite to the muscovite is 15-30:5-10; In step (2), the usage ratio of the modified expanded perlite to the water is 15-30 g: 300-500 mL; In step (2), the target pH value is 5-6.

5. The flame retardant and heat insulating high elastic chemical cross-linked polyethylene high foam material according to claim 1, characterized in that: In step (2), the reaction temperature is 70-80°C and the reaction time is 24-48 hours; In step (2), the vacuum freeze-drying time is 24 to 48 hours; In step (2), the calcination conditions are: atmosphere is inert gas, temperature is 400-500°C, and time is 1-2h.

6. The flame retardant and heat insulating high elastic chemical cross-linked polyethylene high foam material according to claim 1, characterized in that: In step (3), the mass ratio of the composite powder to the 3,4-dihydroxybenzaldehyde is 10-20:3-8; In step (3), the ratio of the composite powder to the ethanol is 10-20 g: 100-300 mL; In step (3), the target pH value is 5-6; In step (3), the mass ratio of the composite powder to the catalyst is 10-20:1-3; In step (3), the catalyst is p-toluenesulfonic acid.

7. The flame retardant and heat insulating high elastic chemical cross-linked polyethylene high foam material according to claim 1, characterized in that: In step (3), the temperature of the first reaction is 50-60°C, and the time of the first reaction is 3-4 hours; In step (3), the temperature of the second reaction is 100-120° C., and the time of the second reaction is 1-3 hours.

8. The flame retardant and heat insulating high elastic chemical cross-linked polyethylene high foam material according to claim 1, characterized in that: The cross-linking agent includes dicumyl peroxide or dibenzoyl peroxide; The blowing agent includes azodicarbonamide.

9. The method for preparing the flame-retardant and heat-insulating high-elasticity chemically cross-linked polyethylene high-foam material according to any one of claims 1 to 8, characterized in that: The following steps are involved: Low-density polyethylene, a cross-linking agent and a flame retardant are mixed, subjected to a first melt extrusion, and then mixed with a foaming agent and subjected to a second melt extrusion to obtain a flame-retardant and heat-insulating high-elasticity chemically cross-linked polyethylene high-foaming material.

10. The method for preparing the flame-retardant and heat-insulating high-elasticity chemically cross-linked polyethylene high-foam material according to claim 9, characterized in that: The temperature of the first melt extrusion is 120-140°C; The temperature of the second melt extrusion is 110-130°C.