Preparation process of flame-retardant high-strength modified SiO2 aerogel-polystyrene composite material

Abstract

The invention relates to the technical field of polystyrene thermal insulation material preparation, and particularly discloses a flame-retardant high-strength modified SiO2 aerogel-polystyrene composite material preparation process, which comprises: (1) mixing powdery SiO2 aerogel and a dihydric phosphate solution, carrying out ultrasonic treatment under a heating condition, separating out a solid product after the ultrasonic treatment is completed, drying, and grinding to obtain a modified SiO2 aerogel-polystyrene composite material; the modified nano SiO2 aerogel powder is obtained. And (2) mixing brucite fibers, dihydric phosphate, polystyrene particles and a foaming agent, heating and mixing, and extruding and granulating to obtain the modified polystyrene particles. And uniformly mixing the modified polystyrene particles with the modified nano SiO2 aerogel powder, and carrying out foaming molding on the obtained mixture in steam to obtain the composite flame-retardant high-strength material. According to the process disclosed by the invention, not only is the dispersity of the powdery SiO2 aerogel improved, so that the flame retardant property of the polystyrene thermal insulation material is better, but also the mechanical property is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of the preparation of polystyrene thermal insulation materials, and particularly relates to a preparation process of a flame-retardant and high-strength modified SiO2 aerogel-polystyrene composite material. Background Art

[0002] Disclosing the information of this background art section is only intended to enhance the overall understanding of the present invention, and is not necessarily regarded as an admission or an implication in any form that this information has become the prior art known to those of ordinary skill in the art.

[0003] Polystyrene (EPS) thermal insulation material is a foam material synthesized by free radical addition polymerization using styrene monomer as the main raw material. It has excellent heat insulation, noise reduction, and thermal insulation properties, and is an ideal material for use as a thermal insulation layer, being widely used in fields such as construction, packaging, and refrigeration. However, polystyrene thermal insulation materials are flammable materials. When exposed to high temperatures or open flames, they are prone to problems such as deformation, collapse, and combustion, which can then trigger fires. Moreover, the combustion is rapid and it is very easy to expand the fire in a short time. Therefore, adding flame retardants to polystyrene thermal insulation materials has become a common method to improve their flame retardant properties.

[0004] Due to its special structure and the property of not burning at high temperatures, etc., SiO2 aerogel has excellent heat insulation and flame retardant properties. Adding powdered SiO2 aerogel to polystyrene thermal insulation materials helps to improve their thermal insulation properties. However, since SiO2 aerogel particles are prone to agglomeration and are not easily uniformly dispersed in polystyrene thermal insulation materials, this not only affects the improvement of the flame retardant properties of polystyrene thermal insulation materials, but also is liable to have an adverse impact on the mechanical properties. Summary of the Invention

[0005] Aiming at the above problems, the present invention provides a preparation process of a SiO2 aerogel-polystyrene composite flame-retardant and high-strength material, which not only improves the dispersibility of powdered SiO2 aerogel, making the flame retardant properties of polystyrene thermal insulation materials better, but also is conducive to the improvement of mechanical properties. Specifically, the technical solution of the present invention is as follows. A preparation process of a SiO2 aerogel-polystyrene composite flame-retardant and high-strength material comprises the following steps: (1) Mix powdered SiO2 aerogel with a dihydrogen phosphate solution and perform ultrasonic treatment under heating conditions. After completion, separate the solid product, dry it and then grind it to obtain modified nano-SiO2 aerogel powder.

[0006] (2) Mix brucite fiber, dihydrogen phosphate, polystyrene particles, and foaming agent, then heat and knead them, and then extrude and pelletize to obtain modified polystyrene particles. Then, mix the modified polystyrene particles with the modified nano-SiO2 aerogel powder evenly, and foam and mold the obtained mixture in steam to obtain the composite flame-retardant high-strength material.

[0007] Further, in step (1), the ratio of the SiO2 aerogel to the dihydrogen phosphate solution is 1 g: 20 - 40 ml. Optionally, the mass fraction of the dihydrogen phosphate solution is 3 - 10%.

[0008] Further, in step (1), the heating temperature is 60 - 90 °C, and the ultrasonic treatment time is 3 - 5 hours.

[0009] Further, in step (1), the drying temperature is 50 - 70 °C, and the drying time is 1 - 2 hours.

[0010] Further, in step (2), the mass ratio of the brucite fiber to the polystyrene particles is 0.16 - 0.23: 1. Optionally, the length of the brucite fiber is 1 - 3 mm, and the diameter is 10 - 15 μm.

[0011] Further, in step (2), the mass ratio of the dihydrogen phosphate to the brucite fiber is 0.045 - 0.07: 0.16 - 0.23.

[0012] Further, in steps (1) and (2), the dihydrogen phosphate includes at least one of potassium dihydrogen phosphate, ammonium dihydrogen phosphate, etc.

[0013] Further, in step (2), the mass ratio of the polystyrene particles to the foaming agent is 1: 0.1 - 0.17. Optionally, the foaming agent includes any one of n-pentane, isopentane, neopentane, etc.

[0014] Further, in step (2), first heat up to 160 - 185 °C and knead for 50 - 90 min, then cool down to 100 - 130 °C and extrude and pelletize.

[0015] Further, in step (2), the mass ratio of the modified polystyrene particles to the modified nano-SiO2 aerogel powder is 1: 0.02 - 0.05.

[0016] Further, in step (2), the method of foaming and molding in steam is as follows: under a gas pressure of 0.4 - 0.55 MPa, first heat the mixture with steam at 80 - 100 °C for 180 - 240 s. Then cure it in an environment with a relative humidity of 92 - 98% for 40 - 60 min, and after completion, naturally dry it at room temperature to obtain the composite flame-retardant high-strength material.

[0017] Compared with the prior art, the technical solution of the present invention has at least the following beneficial effects: The present invention first uses a dihydrogen phosphate solution to modify the surface of SiO2 aerogel particles, and thus utilizes the acidic environment of the dihydrogen phosphate solution under heating conditions. The huge surface area of the particles is used to adsorb dihydrogen phosphate molecules, and the hydroxyl groups on the dihydrogen phosphate molecules are condensed and bonded with the silanol groups on the particle surface, so that the surface of the SiO2 aerogel particles is loaded with dihydrogen phosphate molecules, which can not only form an effective steric hindrance effect to improve the dispersibility of SiO2 aerogel particles, reduce their agglomeration, so that the SiO2 aerogel particles can be more evenly distributed on the surface of the modified polystyrene particles, and thus better improve the flame retardancy of polystyrene. At the same time, the present invention uses brucite fiber and dihydrogen phosphate as the raw materials for preparing the modified polystyrene particles. On the one hand, during the steam heating and curing process, after the brucite fiber releases magnesium ions under the action of the liquid phase formed by the dihydrogen phosphate, it further reacts to form struvite. This product with high strength and high adhesiveness can well improve the bonding force between the brucite fiber and the polystyrene particles, thereby improving the mechanical strength of the polystyrene particles themselves. On the other hand, the brucite fiber on the surface of the modified polystyrene particles also releases magnesium ions under the action of the liquid phase formed by the dihydrogen phosphate on the SiO2 aerogel particles and then further reacts to form struvite, thereby increasing the bonding strength between the polystyrene particles and improving the overall strength of the prepared material. At the same time, the struvite and brucite fiber decompose to release water molecules when heated, and the two form a high-low combination, and together with the burned polystyrene, a charring layer with poor flammability is constructed, which can further strengthen the flame retardancy of polystyrene. In addition, the dihydrogen phosphate can also play a role in promoting the formation of a charring layer or protective layer with heat and oxygen isolation when polystyrene burns, thereby slowing down and preventing the spread of fire and improving the flame retardancy of polystyrene. The above-mentioned multi-faceted strengthening and flame retardant measures make the polystyrene prepared by the present invention have both good flame retardancy and mechanical properties. Description of the Drawings

[0018] The specification drawings forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention.

[0019] Figure 1Sample diagram of the composite flame-retardant high-strength material prepared for Example 1 below.

[0020] Figure 2 Sample diagram of the composite flame-retardant high-strength material prepared for Example 2 below. Detailed implementation mode

[0021] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, any methods and materials similar or equivalent to the described content can be applied to the method of the present invention. The technical solution of the present invention will be further described below in conjunction with the accompanying drawings of the specification and specific embodiments.

[0022] Example 1 A preparation process of a SiO2 aerogel-polystyrene composite flame-retardant high-strength material includes the following steps: (1) Mix powdered SiO2 aerogel with a 5 wt .% potassium dihydrogen phosphate solution in a ratio of 1 g: 30 ml, then heat to 80°C and keep warm, and perform ultrasonic treatment at this temperature for 4.5 hours (ultrasonic power 300 W). After completion, centrifuge the reaction system, separate the solid product, place it in an oven and dry at 60°C for 2 hours, and then grind and disperse the obtained solid to obtain modified nano-SiO2 aerogel powder.

[0023] (2) Mix brucite fibers with a length distribution between 1 and 3 mm and a diameter distribution between 10 and 15 μm, potassium dihydrogen phosphate powder, polystyrene particles, and n-pentane in a mass ratio of 0.2: 0.07: 1: 0.15, stir evenly, then first heat to 175°C and knead for 60 min, then cool to 120°C and extrude and granulate to obtain modified polystyrene particles with a particle size distribution between 2 and 4 mm, and set aside.

[0024] (3) Mix the modified polystyrene particles of this embodiment with the modified nano-SiO2 aerogel powder in a mass ratio of 1: 0.035, stir evenly, and then, under a gas pressure of 0.4 MPa, first heat the obtained mixture with steam at 80°C for 220 s. Then place it in a curing box with a relative humidity controlled between 95 and 98% and cure for 50 min. After completion, naturally dry at room temperature for 24 hours to obtain the SiO2 aerogel-polystyrene composite flame-retardant high-strength material, as Figure 1 shown.

[0025] Performance test: 1. Test the impact strength of the composite flame-retardant high-strength material prepared in this example according to GB / T 1843-2008 "Plastics - Determination of Izod impact strength". 2. Test the limiting oxygen index of the composite flame-retardant high-strength material according to GB / T 2408-2008 "Plastics - Determination of flammability", and the results are as follows: Impact strength = 23.41 KJ / m 2 , and the limiting oxygen index = 48.17%.

[0026] Example 2 A preparation process of a SiO2 aerogel-polystyrene composite flame-retardant high-strength material includes the following steps: (1) Mix powdered SiO2 aerogel with a 3 wt .% potassium dihydrogen phosphate solution in a ratio of 1 g:40 ml, heat to 90 °C for insulation, and perform ultrasonic treatment for 3 hours (ultrasonic power 400 W) at this temperature. After completion, centrifuge the reaction system, separate the solid product, place it in an oven and dry it at 50 °C for 2 hours, and then grind and disperse the obtained solid to obtain modified nano-SiO2 aerogel powder.

[0027] (2) Mix brucite fibers with a length distribution of 1-3 mm and a diameter distribution of 10-15 μm, potassium dihydrogen phosphate powder, polystyrene particles, and isopentane in a mass ratio of 0.23:0.06:1:0.17, stir evenly, then first heat to 185 °C and knead for 50 min, and then cool to 130 °C and extrude and pelletize to obtain modified polystyrene particles with a particle size distribution between 2-4 mm for standby.

[0028] (3) Mix the modified polystyrene particles of this example and the modified nano-SiO2 aerogel powder in a mass ratio of 1:0.05, stir evenly, and then, under a gas pressure of 0.5 MPa, first heat the obtained mixture with steam at 100 °C for 180 s. Then place it in a curing box with a relative humidity controlled between 92-95% and cure for 60 min. After completion, dry it naturally at room temperature for 24 hours to obtain the SiO2 aerogel-polystyrene composite flame-retardant high-strength material, as Figure 2 shown.

[0029] Performance test: 1. Test the impact strength of the composite flame-retardant high-strength material prepared in this example according to GB / T 1843-2008 "Plastics - Determination of Izod impact strength". 2. Test the limiting oxygen index of the composite flame-retardant high-strength material according to GB / T 2408-2008 "Plastics - Determination of flammability", and the results are as follows: Impact strength = 25.69 KJ / m 2 , and the limiting oxygen index = 51.04%.

[0030] Example 3 Preparation process of a SiO2 aerogel - polystyrene composite flame - retardant high - strength material, comprising the following steps: (1) Mix powdered SiO2 aerogel with a 10 wt .% potassium dihydrogen phosphate solution in a ratio of 1 g:20 ml, then heat to 60 °C for heat preservation, and perform ultrasonic treatment at this temperature for 5 hours (ultrasonic power 300 W). After completion, centrifuge the reaction system, separate the solid product, place it in an oven and dry at 70 °C for 1 hour, and then grind and disperse the obtained solid to obtain modified nano - SiO2 aerogel powder.

[0031] (2) Mix brucite fibers with a length distribution between 1 - 3 mm and a diameter distribution between 10 - 15 μm, potassium dihydrogen phosphate powder, polystyrene particles, and pentane in a mass ratio of 0.16:0.045:1:0.1, stir evenly, then first heat up to 160 °C for kneading for 90 min, and then cool down to 100 °C for extrusion granulation to obtain modified polystyrene particles with a particle size distribution between 2 - 4 mm, and set aside.

[0032] (3) Mix the modified polystyrene particles of this example with the modified nano - SiO2 aerogel powder in a mass ratio of 1:0.02, stir evenly, and then, under a gas pressure of 0.55 MPa, first heat the obtained mixture with steam at 90 °C for 240 s. Then place it in a curing box with a relative humidity controlled between 92 - 95% for curing for 40 min, and after completion, naturally dry at room temperature for 24 hours to obtain the SiO2 aerogel - polystyrene composite flame - retardant high - strength material.

[0033] Performance test: 1. Test the impact strength of the composite flame - retardant high - strength material prepared in this example according to GB / T1843 - 2008 "Plastics - Izod impact strength". 2. Test the limiting oxygen index of the composite flame - retardant high - strength material according to GB / T2408 - 2008 "Determination of flammability of plastics", and the results are: impact strength = 20.86 KJ / m 2 , limiting oxygen index = 43.23%.

[0034] Example 4 Preparation process of a SiO2 aerogel - polystyrene composite flame - retardant high - strength material, comprising the following steps: (1) Mix antigorite fibers with a length distribution between 1 and 3 mm and a diameter distribution between 10 and 15 μm, potassium dihydrogen phosphate powder, polystyrene particles, and n-pentane in a mass ratio of 0.2:0.07:1:0.15, and stir evenly. Then, first heat to 175 °C and knead for 60 min, and then cool to 120 °C and extrude and pelletize to obtain modified polystyrene particles with a particle size distribution between 2 and 4 mm for standby.

[0035] (2) Mix the modified polystyrene particles of this example with the same powdery SiO2 aerogel used in step (1) of Example 1 above in a mass ratio of 1:0.07, and stir evenly. Then, under a gas pressure of 0.4 MPa, first heat the obtained mixture with steam at 80 °C for 220 s. Then, place it in a curing box with a relative humidity controlled between 95% and 98% and cure for 50 min. After completion, dry naturally at room temperature for 24 hours to obtain the SiO2 aerogel-polystyrene composite flame-retardant high-strength material.

[0036] Performance test: 1. Test the impact strength of the composite flame-retardant high-strength material prepared in this example according to GB / T1843-2008 "Plastics - Izod impact strength". 2. Test the limiting oxygen index of the composite flame-retardant high-strength material according to GB / T2408-2008 "Determination of flammability of plastics", and the results are: impact strength = 20.57 KJ / m 2 and limiting oxygen index = 37.34%.

[0037] Example 5 A preparation process of a SiO2 aerogel-polystyrene composite flame-retardant high-strength material includes the following steps: (1) Mix powdery SiO2 aerogel with a 3 wt .% potassium dihydrogen phosphate solution in a ratio of 1 g:40 ml, heat to 90 °C and keep warm, and perform ultrasonic treatment at this temperature for 3 hours (ultrasonic power 400 W). After completion, centrifuge the reaction system, separate the solid product, place it in an oven and dry at 50 °C for 2 hours, and then grind and disperse the obtained solid to obtain modified nano-SiO2 aerogel powder.

[0038] (2) Mix antigorite fibers with a length distribution between 1 and 3 mm and a diameter distribution between 10 and 15 μm, polystyrene particles, and isopentane in a mass ratio of 0.23:1:0.17, and stir evenly. Then, first heat to 185 °C and knead for 50 min, and then cool to 130 °C and extrude and pelletize to obtain modified polystyrene particles with a particle size distribution between 2 and 4 mm for standby.

[0039] (3) Mix the modified polystyrene particles of this example with the modified nano-SiO₂ aerogel powder at a mass ratio of 1:0.05, stir evenly, and then, under a pressure of 0.5 MPa, first heat the obtained mixture with steam at 100 °C for 180 s. Then place it in a curing box with a relative humidity controlled between 92% and 95% for curing for 60 min. After completion, naturally dry it at room temperature for 24 hours to obtain the SiO₂ aerogel-polystyrene composite flame-retardant high-strength material.

[0040] Performance test: 1. Test the impact strength of the composite flame-retardant high-strength material prepared in this example according to GB / T1843-2008 "Plastics - Izod impact strength". 2. Test the limiting oxygen index of the composite flame-retardant high-strength material according to GB / T2408-2008 "Determination of burning behavior of plastics". The results are as follows: Impact strength = 21.44 KJ / m 2 , Limiting oxygen index = 38.19%.

[0041] Example 6 A preparation process of a SiO₂ aerogel-polystyrene composite flame-retardant high-strength material comprises the following steps: (1) Mix the powdery SiO₂ aerogel with a 5 wt .% potassium dihydrogen phosphate solution at a ratio of 1 g:30 ml, heat to 80 °C for insulation, and perform ultrasonic treatment at this temperature for 4.5 hours (ultrasonic power 300 W). After completion, centrifuge the reaction system, separate the solid product, place it in an oven and dry it at 60 °C for 2 hours, and then grind and disperse the obtained solid to obtain the modified nano-SiO₂ aerogel powder.

[0042] (2) Mix potassium dihydrogen phosphate powder, polystyrene particles, and n-pentane at a mass ratio of 0.07:1:0.15, stir evenly, then first raise the temperature to 175 °C for kneading for 60 min, and then lower the temperature to 120 °C for extrusion granulation to obtain modified polystyrene particles with a particle size distribution between 2 and 4 mm, and set aside.

[0043] (3) Mix the modified polystyrene particles of this example with the modified nano-SiO₂ aerogel powder at a mass ratio of 1:0.035, stir evenly, and then, under a pressure of 0.4 MPa, first heat the obtained mixture with steam at 80 °C for 220 s. Then place it in a curing box with a relative humidity controlled between 95% and 98% for curing for 50 min. After completion, naturally dry it at room temperature for 24 hours to obtain the SiO₂ aerogel-polystyrene composite flame-retardant high-strength material.

[0044] Performance test: 1. Test the impact strength of the composite flame-retardant high-strength material prepared in this example according to GB / T 1843-2008 "Plastics - Izod impact strength". 2. Test the limiting oxygen index of the composite flame-retardant high-strength material according to GB / T 2408-2008 "Determination of flammability of plastics", and the results are: impact strength = 15.98 KJ / m 2 , limiting oxygen index = 41.76%.

[0045] Example 7 A preparation process of a SiO2 aerogel - polystyrene composite flame-retardant high-strength material includes the following steps: (1) Mix powdered SiO2 aerogel with a 10 wt .% potassium dihydrogen phosphate solution in a ratio of 1 g:20 ml, heat to 60°C for insulation, and perform ultrasonic treatment at this temperature for 5 hours (ultrasonic power 300 W). After completion, centrifuge the reaction system, separate the solid product, place it in an oven and dry it at 70°C for 1 hour, and then grind and disperse the obtained solid to obtain modified nano-SiO2 aerogel powder.

[0046] (2) Mix brucite fibers with a length distribution of 1 - 3 mm and a diameter distribution of 10 - 15 μm, potassium dihydrogen phosphate powder, polystyrene particles, and pentane in a mass ratio of 0.16:0.045:1:0.1, stir evenly, then first raise the temperature to 160°C and knead for 90 min, then lower the temperature to 100°C and extrude and pelletize to obtain modified polystyrene particles with a particle size distribution between 2 - 4 mm for standby.

[0047] (3) Mix the modified polystyrene particles of this example and the modified nano-SiO2 aerogel powder in a mass ratio of 1:0.02, stir evenly, and then under a gas pressure of 0.55 MPa, first heat the obtained mixture with steam at 90°C for 240 s, and after completion, naturally dry it at room temperature for 24 hours to obtain the SiO2 aerogel - polystyrene composite flame-retardant high-strength material.

[0048] Performance test: 1. Test the impact strength of the composite flame-retardant high-strength material prepared in this example according to GB / T 1843-2008 "Plastics - Izod impact strength". 2. Test the limiting oxygen index of the composite flame-retardant high-strength material according to GB / T 2408-2008 "Determination of flammability of plastics", and the results are: impact strength = 16.18 KJ / m 2 , limiting oxygen index = 39.52%.

[0049] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements for some of the technical features. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. Preparation process of a SiO2 aerogel-polystyrene composite flame-retardant high-strength material, characterized in that, It includes the following steps: (1) Mix powdery SiO2 aerogel with a dihydrogen phosphate solution, conduct ultrasonic treatment under heating conditions, separate the solid product after completion, dry and grind it to obtain modified nano-SiO2 aerogel powder; (2) Mix brucite fiber, dihydrogen phosphate, polystyrene particles, and a foaming agent, heat and knead them, and then extrude and granulate to obtain modified polystyrene particles; then mix the modified polystyrene particles with the modified nano-SiO2 aerogel powder evenly, and foam and mold the obtained mixture in steam to obtain the composite flame-retardant high-strength material.

2. The preparation process of the SiO2 aerogel-polystyrene composite flame-retardant high-strength material according to claim 1, characterized in that, In step (1), the ratio of the SiO2 aerogel to the dihydrogen phosphate solution is 1 g: 20-40 ml; optionally, the mass fraction of the dihydrogen phosphate solution is 3-10%.

3. The preparation process of the SiO2 aerogel-polystyrene composite flame-retardant high-strength material according to claim 1, characterized in that, In step (1), the heating temperature is 60-90 °C, and the ultrasonic treatment time is 3-5 hours; Optionally, in step (1), the drying temperature is 50-70 °C, and the drying time is 1-2 hours.

4. The preparation process of the SiO2 aerogel-polystyrene composite flame-retardant high-strength material according to claim 1, characterized in that, In step (2), the mass ratio of the brucite fiber to the polystyrene particles is 0.16-0.23: 1; Optionally, in step (2), the length of the brucite fiber is 1-3 mm, and the diameter is 10-15 μm.

5. The preparation process of the SiO2 aerogel-polystyrene composite flame-retardant high-strength material according to claim 1, characterized in that, In step (2), the mass ratio of the dihydrogen phosphate to the brucite fiber is 0.045-0.07: 0.16-0.

23.

6. The preparation process of the SiO2 aerogel-polystyrene composite flame-retardant high-strength material according to claim 1, characterized in that, In step (2), the mass ratio of the polystyrene particles to the foaming agent is 1: 0.1-0.17; Optionally, in step (2), the foaming agent includes any one of n-pentane, isopentane, and neopentane.

7. The preparation process of the SiO2 aerogel-polystyrene composite flame-retardant high-strength material according to claim 1, characterized in that, In step (2), first raise the temperature to 160-185 °C and knead for 50-90 min, then lower the temperature to 100-130 °C and extrude and granulate.

8. The preparation process of the SiO2 aerogel-polystyrene composite flame-retardant high-strength material according to claim 1, characterized in that, In step (2), the mass ratio of the modified polystyrene particles to the modified nano-SiO2 aerogel powder is 1: 0.02-0.

05.

9. The preparation process of the SiO2 aerogel-polystyrene composite flame-retardant high-strength material according to any one of claims 1-8, characterized in that, In steps (1) and (2), the dihydrogen phosphate includes at least one of potassium dihydrogen phosphate and ammonium dihydrogen phosphate.

10. The preparation process of the SiO2 aerogel-polystyrene composite flame-retardant high-strength material according to any one of claims 1-8, characterized in that, In step (2), the method of foaming and molding in steam is: under a gas pressure of 0.4-0.55 MPa, first heat the mixture with steam at 80-100 °C for 180-240 s; then cure it in an environment with a relative humidity of 92-98% for 40-60 min, and after completion, naturally dry it at room temperature to obtain the composite flame-retardant high-strength material.

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