Flame-retardant and heat-insulating aerogel composite material as well as preparation method and application thereof

Abstract

The invention relates to a flame-retardant and heat-insulating aerogel composite material as well as a preparation method and application thereof, and belongs to the technical field of novel building materials. The fiber aerogel is prepared through coaxial electrostatic spinning, an injector containing a polymer spinning solution is connected to a skin layer needle tube connecting port, an injector containing air is connected to a core layer needle tube connecting port, coaxial electrostatic spinning is carried out to prepare micron fibers with skin-core structures, the micron fibers fall on a receiving base material, and the micron fibers with the skin-core structures fall on the receiving base material. A hollow fiber aerogel material with a three-dimensional fluffy structure is obtained, in-situ growth of hydrated nano silicate particles is carried out after thermal crosslinking treatment, the nano silicate particles grow along the fiber surface and cover the micron fiber surface of the hollow fiber aerogel material, and the aerogel composite material is obtained. The hydrated nano silicate particle growth solution comprises polyvinyl alcohol, calcium salt, silicate and aluminum salt. The prepared aerogel composite material has excellent flame retardance and heat insulation performance and is suitable for being used as a building material.

Description

Technical Field

[0001] The present application relates to a flame-retardant and heat-insulating aerogel composite material and a preparation method and application thereof, belonging to the technical field of new building materials. Background Art

[0002] Data shows that about 40% of the world's energy consumption comes from building operations, of which HVAC systems account for the highest proportion of energy consumption. Among the building envelope structures, heat loss from walls and roofs alone accounts for 40% of the total heat conduction. Therefore, the development of high-efficiency thermal insulation functional materials is of great value in promoting the green transformation of the construction industry. It is necessary to develop new building materials that are lightweight, high-strength and have excellent thermal insulation properties.

[0003] Aerogel, defined as a nanoporous solid material formed by random crosslinking of nanoparticles or polymer molecules in three dimensions, is a special form of solid matter. Aerogel, characterized by low density, high specific surface area, and high porosity, is a lightweight, porous nanomaterial with numerous excellent properties and a wide range of applications, demonstrating its potential in numerous fields.

[0004] Prior art patent CN 113683812 A discloses a flame-retardant and heat-insulating polyimide nanofiber aerogel and a preparation method thereof. The method first uses polyamide acid to prepare polyamic acid by condensation polymerization of polyacid anhydrides and polyamines, then adds a silica precursor thereto, and obtains a polyamic acid / silica nanofiber membrane by electrospinning and hydrolysis. The nanofibers are then dispersed in a solvent and freeze-dried to prepare a polyamic acid / silica nanofiber aerogel. Finally, the nanofibers are subjected to high-temperature thermal imidization treatment to obtain a polyimide nanofiber aerogel with a silica layer coated on the surface.

[0005] Prior art patent CN 113511856 A discloses a method for preparing a high-performance sound-absorbing and heat-insulating aerogel fiber concrete composite material. The method combines aerogel fibers with high-performance self-compacting plain concrete technology and uses non-woven alumina-silica aerogel nanofibers as a functional reinforcement phase. The resulting composite material retains the original decorative effects of high-performance plain concrete, such as color and surface texture, while also having good sound absorption and heat insulation properties. At the same time, its mechanical properties such as strength, toughness, and hardness are significantly improved, and it has good plasticity and appearance texture.

[0006] Prior art patent CN 107190365 A discloses a silica aerogel composite fiber and a preparation method thereof, comprising the following steps: preparing a silica wet gel; mixing the silica wet gel with an organic solvent in a volume ratio of 1:(8-30), then adding a crosslinker solution for a crosslinking reaction to obtain a spinning solution with a concentration of 0.5-1.5 g / mL; electrospinning the spinning solution and drying it at normal pressure to obtain a foamed silica aerogel composite fiber, wherein the crosslinker solution is prepared from hydroxyl silicone oil, polyacrylic acid, and an organic solvent in a mass ratio of 1:(1-10):(1-30).

[0007] The prior art patent CN 120041956 A discloses an aerogel composite fiber flame retardant thermal insulation material and its preparation method and application, including 0.5-2.5 parts of SiO2 aerogel particles, 18-21 parts of polymer, 1-3 parts of inorganic flame retardant, 1-3 parts of Al2O3 microbeads and 0.9-3.2 parts of cross-linking agent; the SiO2 aerogel particles and inorganic flame retardant are wrapped inside the aerogel composite fiber flame retardant thermal insulation material, and the Al2O3 microbeads are loaded on the surface of the aerogel composite fiber flame retardant thermal insulation material.

[0008] The technical solution of CN 107190365 A involves spinning a mixture of wet silica gel and a spinning solution, followed by a drying process to prepare composite fibers containing silica aerogel. The silica aerogel particles contained in a single organic fiber do not form a three-dimensional fiber stacking structure and are not fiber aerogels. Consequently, there is still room for improvement in the thermal insulation, fire resistance, and high-temperature resistance of the composite fibers.

[0009] Prior patent CN 120041956 A directly added ready-made aerogel particles as functional additives into the spinning solution to prepare composite fibers, and then loaded inorganic particles on the surface of the composite fibers. Since this method adds a lot of powder and particles, it makes spinning more difficult, and there is a possibility that the loaded inorganic particles will fall off.

[0010] Therefore, it is necessary to provide a novel flame retardant and heat insulating aerogel composite material to solve the problems of flame retardant and heat insulating building materials in the prior art. Summary of the Invention

[0011] In order to solve the above problems, a flame-retardant and heat-insulating aerogel composite material, a preparation method and application thereof are provided. A micron fiber aerogel with a skin-core structure is prepared by coaxial electrospinning, which is then subjected to thermal cross-linking treatment and then in-situ growth of hydrated nanosilicate particles. The nanosilicate particles grow along the fiber surface and cover the micron fiber surface of the hollow fiber aerogel material. The obtained aerogel composite material has excellent flame retardant and heat-insulating properties and is suitable for use as a building material.

[0012] The present application provides a method for preparing a flame-retardant and heat-insulating aerogel composite material, the preparation method comprising the following steps:

[0013] S1. Preparing a spinning solution: dissolving a polymer material in an organic solvent and stirring to dissolve the polymer material, and then adding a cross-linking agent to obtain a polymer material solution for use;

[0014] S2. Coaxial electrospinning to prepare fiber aerogel: Connect a syringe containing a polymer spinning solution to the skin layer needle tube connection port, and connect a syringe containing air to the core layer needle tube connection port. Coaxial electrospinning is performed to prepare micron fibers with a skin-core structure. The micron fibers fall onto a receiving substrate to obtain a hollow fiber aerogel material with a three-dimensional fluffy structure.

[0015] S3, thermal crosslinking treatment: heating the obtained hollow fiber aerogel material to perform crosslinking;

[0016] S4. In-situ growth of hydrated nanosilicate particles: placing the cross-linked hollow fiber aerogel material in a hydrated nanosilicate particle growth solution, so that the nanosilicate particles grow along the fiber surface and cover the micron fiber surface of the hollow fiber aerogel material;

[0017] S5, obtaining the aerogel composite material after drying;

[0018] The hydrated nano-silicate particle growth liquid comprises polyvinyl alcohol, calcium nitrate, sodium silicate and aluminum nitrate, and the mass ratio of the polyvinyl alcohol, calcium nitrate, sodium silicate and aluminum nitrate is (5-15): (40-60): (30-50): (5-15).

[0019] Compared with the existing technical solutions, the present application solution uses a coaxial electrospinning process to prepare a hollow fiber aerogel composite material. The hollow fiber structure and the aerogel spatial structure give the material excellent thermal insulation performance and low thermal conductivity. In addition, by in situ growing hydrated nano calcium aluminum silicate particles, a dense inorganic fireproof protective layer can be formed on the outer layer of the fiber, achieving Class A fire protection, while greatly improving the mechanical properties of the material.

[0020] Optionally, the preparation method of the hydrated nano-silicate particle growth liquid includes:

[0021] 1) dissolving polyvinyl alcohol in deionized water;

[0022] 2) adding calcium nitrate solution for cross-linking;

[0023] 3) adding sodium silicate solution and aluminum nitrate solution to generate in situ Ca-Al-Si-H nanoparticles.

[0024] Optionally, the polyvinyl alcohol has a molecular weight of 180,000 to 220,000. Polyvinyl alcohol with this molecular weight has a high degree of polymerization. As the degree of polymerization increases, the viscosity of the aqueous solution increases, improving the strength and solvent resistance of the formed film. However, a too high molecular weight can result in a solution with excessively high viscosity, making it difficult to use; while a too low molecular weight can also result in low viscosity, making it difficult to load nanoparticles during in situ growth.

[0025] Optionally, the crosslinking condition in step S3 is 70-90° C. for 40-80 minutes. This crosslinking condition is mild and moderate, and there is no problem of ineffectiveness or poor effect due to too low a temperature, nor is there a problem of excessive crosslinking and damage to the fiber material due to too high a temperature.

[0026] Optionally, in the coaxial electrospinning technique of step S2, the spinning voltage is 15-25 kV, the spinning distance is 15-25 cm, the receiving drum speed is 30-70 rpm, the perfusion rate of the skin layer syringe is 1-4 ml / h, the perfusion rate of the core layer syringe is 0.5-2 ml / h, the ambient temperature is 25±2°C, and the relative humidity is 70-90%. The perfusion rates of the skin and core layers affect the formation of the skin-core structure, and the above processing parameters can achieve a good skin-core structure formation effect; the ambient humidity affects the formation of the three-dimensional fluffy structure. Low humidity will not result in fluffiness, while humidity above 90% will cause the fibers to solidify too quickly, resulting in poor forming effect.

[0027] Optionally, the perfusion speed of the skin layer syringe is at least 1.5 times the perfusion speed of the core layer syringe;

[0028] Optionally, the perfusion rate of the skin layer syringe is at least twice the perfusion rate of the core layer syringe.

[0029] Optionally, the receiving substrate in step S2 is a polyester nonwoven fabric. It should be noted that the receiving substrate is only used to receive the hollow fiber aerogel material, and those skilled in the art may also choose other materials.

[0030] Optionally, the polymer material in step S1 is one or both of polysulfone or polystyrene; the above two materials are used as raw materials for preparing fibers, and can easily form a fluffy three-dimensional fiber stacking structure in a high-humidity environment, which is beneficial to improving thermal insulation performance. Compared with other polymer materials, they have obvious advantages and are easier to form a fluffy structure.

[0031] Optionally, the concentration of the polymer material in the polymer material solution in step S1 is 18-22 wt %. If the concentration is too low, the viscosity of the spinning solution is low and it is difficult to form fibers. If the concentration is too high, the viscosity of the spinning solution is too high and it is difficult to spin.

[0032] Optionally, the molecular weight of the polysulfone is 60,000 to 80,000;

[0033] Optionally, the molecular weight of the polystyrene is 300,000 to 400,000;

[0034] The above molecular weight range has good spinnability during the spinning process. If the molecular weight is too low, the viscosity of the spinning solution is low and it is difficult to form fibers; if the molecular weight is too high, the viscosity of the spinning solution is too high and it is also difficult to spin.

[0035] Optionally, the organic solvent in step S1 is one or more of dimethylformamide, dimethylacetamide, acetone, polymethyl sulfoxide, and tetrahydrofuran. It should be noted that those skilled in the art can also select other feasible solvents as needed.

[0036] Optionally, the cross-linking agent in step S1 is one or more of aziridine, dicumyl peroxide and benzoyl peroxide;

[0037] Optionally, the concentration of the crosslinking agent in the polymer material solution is 5-15 wt %. If the concentration is too low, the crosslinking effect is not obvious, while if the concentration is too high, the fiber membrane morphology will be destroyed.

[0038] Optionally, in step S4, the cross-linked hollow fiber aerogel material is immersed in a hydrated nano-silicate particle growth liquid for at least 2 hours, optionally 2 to 10 hours, or optionally 2 to 6 hours.

[0039] Optionally, in step S4, the cross-linked hollow fiber aerogel material is placed in a hydrated nano-silicate particle growth liquid, and the volume ratio of the hollow fiber aerogel material to the hydrated nano-silicate particle growth liquid is 1:(3-30), optionally, 1:(5-20), optionally, 1:(5-15).

[0040] Optionally, the hollow fiber aerogel material is pre-soaked in a hydrated nano-silicate particle growth solution to which sodium silicate and aluminum nitrate have not yet been added, and then sodium silicate and aluminum nitrate are added.

[0041] The present application provides an aerogel composite material prepared by the above-mentioned method for preparing the flame-retardant and heat-insulating aerogel composite material.

[0042] The present application provides the application of the above-mentioned aerogel composite material in building materials.

[0043] The beneficial effects of this application include but are not limited to:

[0044] 1. According to the flame-retardant, heat-insulating aerogel composite material and its preparation method and application in this application, a hollow fiber aerogel composite material is prepared by a coaxial electrospinning process. The hollow fiber structure and the aerogel spatial structure give the material excellent thermal insulation performance and low thermal conductivity. By in situ growing hydrated nano calcium aluminum silicate particles, a dense inorganic fireproof protective layer can be formed on the outer layer of the fiber, achieving Class A fire protection, while greatly improving the mechanical properties of the material.

[0045] 2. According to the flame-retardant and heat-insulating aerogel composite material and its preparation method and application in this application, the obtained aerogel composite material has the advantages of light weight, high efficiency thermal insulation, Class A flame retardancy, and high mechanical strength, which is convenient for construction application in construction projects.

[0046] 3. According to the flame-retardant, heat-insulating aerogel composite material and its preparation method and application in this application, the preparation process of this application scheme is simple, the aerogel fluffy structure can be achieved without the need for a freeze-drying process, and Class A fire protection can be achieved without the need for high-temperature calcination of organic materials into inorganic materials, with lower energy consumption.

[0047] 4. According to the flame-retardant and heat-insulating aerogel composite material, its preparation method and application in this application, the preparation method of the flame-retardant and heat-insulating aerogel composite material provided by the present application scheme has the advantages of convenient operation and stable product quality compared with the preparation method of products with similar functions in the prior art. The prepared product has better performance and has comprehensive excellent properties of flame retardancy, heat insulation, light weight and high strength.

[0048] 5. According to the flame-retardant and heat-insulating aerogel composite material and its preparation method and application in this application, this application scheme adopts a coaxial electrospinning process combined with the technology of in-situ growth of hydrated nano-calcium aluminum silicate particles to prepare a flame-retardant and heat-insulating aerogel composite material with excellent performance. No similar products or related reports have been seen so far. This application scheme is of great significance for the research of new building materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0050] Figure 1 Schematic diagram of the coaxial electrospinning process involved in the embodiment of the present application;

[0051] Figure 2 This is the hollow fiber aerogel material product involved in the embodiments of this application;

[0052] Figure 3 Schematic diagram of the structure of the hollow fiber in the hollow fiber aerogel material involved in the embodiment of the present application;

[0053] Figure 4 Schematic diagram of the growth of hydrated nano-calcium aluminum silicate particles in the aerogel composite material involved in the embodiment of the present application. DETAILED DESCRIPTION

[0054] The present application is described in detail below with reference to examples, but the present application is not limited to these examples. Unless otherwise specified, the raw materials and reagents in the examples of the present application are purchased through commercial channels.

[0055] Example 1

[0056] 1) Preparation of spinning solution: Using polysulfone (PSU, molecular weight 60,000-80,000) as raw material and dimethylformamide (DMF) as organic solvent, a spinning solution with a polymer mass fraction concentration of 20 wt% was prepared, magnetic stirring was performed for 4 h, and an aziridine crosslinker was added as a crosslinker at a concentration of 10 wt%;

[0057] 2) Preparation of fiber aerogel by coaxial electrospinning technology: Micron fibers with skin-core structure are prepared by coaxial electrospinning process, in which the skin layer is a polymer and the core layer is air, thus forming a Figure 3 The fiber aerogel material with a hollow structure is shown;

[0058] like Figure 1 As shown, the polymer spinning solution is injected into the syringe, the syringe is connected to the cortical needle tube connection port, and the syringe containing air is connected to the core needle tube connection port to perform coaxial electrospinning; wherein, polyester non-woven fabric is used as the receiving substrate, the spinning voltage is 20kV, the spinning distance is 20cm, the receiving drum speed is 50rpm, the perfusion speed of the cortical syringe is 3ml / h, the perfusion speed of the core syringe is 1.5ml / h, the ambient temperature is 25℃, and the ambient relative humidity is 80%. Finally, the following is obtained. Figure 2 The hollow fiber aerogel material with a three-dimensional fluffy structure shown;

[0059] 3) Thermal crosslinking treatment: The obtained fiber aerogel material is placed in an air environment and heated for 1 hour at 80°C. Under the action of the crosslinking agent, the fibers are crosslinked with each other, thereby improving the stability of the three-dimensional spatial structure;

[0060] 4) In situ growth of hydrated nanosilicate particles: The cross-linked fiber aerogel is placed in a hydrated nanosilicate particle growth solution and soaked for 4 hours. The volume ratio of the hollow fiber to the hydrated nanosilicate particle growth solution is controlled at 1:10. Figure 4 As shown, the nano-silicate particles begin to grow along the fiber surface and eventually completely cover the fiber surface of the aerogel, forming an inorganic fireproof layer and improving the mechanical properties of the aerogel.

[0061] The raw materials for preparing the growth liquid are polyvinyl alcohol (PVA, the molecular weight of polyvinyl alcohol is 180,000 to 220,000), Ca(NO3)2·4H2O, Na2SiO3·9H2O and Al(NO3)3·9H2O; the preparation method is as follows: 10g PVA is dissolved in 100g deionized water and magnetically stirred at 90°C for 1h; then, 50g Ca(NO3)2 solution (concentration 1mol / L) is added to the PVA solution for cross-linking; next, 40g Na2SiO3 (concentration 1mol / L) and 10g Al(NO3)3 (concentration 1mol / L) solutions are added successively to generate in-situ Ca-Al-Si-H nanoparticles. Before adding Na2SiO3 and Al(NO3)3, the hollow fiber aerogel material that has been heat-crosslinked is immersed in the growth liquid. After adding Na2SiO3 and Al(NO3)3, nanoparticles are generated in situ. The chemical equation can be expressed as: Ca 2+ +SiO 2- +3Al 3+ +H2O→(CaO) x (Al2O3)SiO2(H2O) y , and the transparent solution gradually turned milky white with the addition of sodium silicate, which means that Ca-Al-Si-H nanoparticles were generated. The above operation was carried out at room temperature;

[0062] 5) Drying: Drying in an environment of 80° C. until the moisture is completely removed to obtain a hollow fiber aerogel material.

[0063] Example 2

[0064] 1) Preparation of spinning solution: Using polystyrene (PS, molecular weight 300,000-400,000) as raw material and dimethylacetamide (DMAc) as organic solvent, a spinning solution with a polymer mass fraction concentration of 22 wt% was prepared, magnetic stirring was performed for 5 h, and dicumyl peroxide was added as a crosslinker at an amount of 15 wt%;

[0065] 2) Preparation of fiber aerogel by coaxial electrospinning technology: Micron fibers with skin-core structure are prepared by coaxial electrospinning process, in which the skin layer is a polymer and the core layer is air, thus forming a Figure 3 The fiber aerogel material with a hollow structure is shown;

[0066] like Figure 1As shown, the polymer spinning solution is injected into the syringe, the syringe is connected to the cortical needle tube connection port, and the syringe containing air is connected to the core needle tube connection port to perform coaxial electrospinning; wherein, polyester non-woven fabric is used as the receiving substrate, the spinning voltage is 25kV, the spinning distance is 20cm, the receiving drum speed is 50rpm, the perfusion speed of the cortical syringe is 4ml / h, the perfusion speed of the core syringe is 2ml / h, the ambient temperature is 27℃, and the ambient relative humidity is 85%, and finally the following is obtained. Figure 2 The hollow fiber aerogel material with a three-dimensional fluffy structure shown;

[0067] 3) Thermal crosslinking treatment: The obtained fiber aerogel material is placed in an air environment at 70°C and heated for 80 minutes. Under the action of the crosslinking agent, the fibers are crosslinked with each other, thereby improving the stability of the three-dimensional spatial structure;

[0068] 4) In situ growth of hydrated nanosilicate particles: The cross-linked fiber aerogel is placed in a hydrated nanosilicate particle growth solution and soaked for 3 hours. The volume ratio of the hollow fiber to the hydrated nanosilicate particle growth solution is controlled at 1:10. Figure 4 As shown, the nano-silicate particles begin to grow along the fiber surface and eventually completely cover the fiber surface of the aerogel, forming an inorganic fireproof layer and improving the mechanical properties of the aerogel.

[0069] The raw materials for preparing the growth liquid are polyvinyl alcohol (PVA, the molecular weight of polyvinyl alcohol is 180,000 to 220,000), Ca(NO3)2·4H2O, Na2SiO3·9H2O and Al(NO3)3·9H2O; the preparation method is: 5g PVA is dissolved in 100g deionized water and magnetically stirred at 90°C for 1h; then, 40g Ca(NO3)2 solution (concentration 1mol / L) is added to the PVA solution for cross-linking; next, 30g Na2SiO3 (concentration 1mol / L) and 5g Al(NO3)3 (concentration 1mol / L) solution are added continuously to generate in-situ Ca-Al-Si-H nanoparticles. Before adding Na2SiO3 and Al(NO3)3, the hollow fiber aerogel material after thermal cross-linking treatment has been immersed in the growth liquid. After adding Na2SiO3 and Al(NO3)3, nanoparticles are generated in situ. The chemical equation can be expressed as: Ca 2+ +SiO 2- +3Al 3+ +H2O→(CaO) x (Al2O3)SiO2(H2O) y , and the transparent solution gradually turned milky white with the addition of sodium silicate, which means that Ca-Al-Si-H nanoparticles were generated. The above operation was carried out at room temperature;

[0070] 5) Drying: Drying in an environment of 80° C. until the moisture is completely removed to obtain a hollow fiber aerogel material.

[0071] Example 3

[0072] 1) Preparation of a spinning solution: Using polysulfone (PSU, molecular weight 60,000-80,000) as a raw material and tetrahydrofuran (THF) as an organic solvent, a spinning solution with a polymer mass fraction concentration of 18 wt% was prepared, magnetic stirring was performed for 3 h, and benzoyl peroxide was added as a crosslinking agent at a concentration of 5 wt%;

[0073] 2) Preparation of fiber aerogel by coaxial electrospinning technology: Micron fibers with skin-core structure are prepared by coaxial electrospinning process, in which the skin layer is a polymer and the core layer is air, thus forming a Figure 3 The fiber aerogel material with a hollow structure is shown;

[0074] like Figure 1 As shown, the polymer spinning solution is injected into the syringe, the syringe is connected to the cortical needle tube connection port, and the syringe containing air is connected to the core needle tube connection port to perform coaxial electrospinning; wherein, polyester non-woven fabric is used as the receiving substrate, the spinning voltage is 15kV, the spinning distance is 20cm, the receiving drum speed is 50rpm, the perfusion rate of the cortical syringe is 1ml / h, the perfusion rate of the core syringe is 0.5ml / h, the ambient temperature is 23℃, and the ambient relative humidity is 75%, and finally the following is obtained. Figure 2 The hollow fiber aerogel material with a three-dimensional fluffy structure shown;

[0075] 3) Thermal crosslinking treatment: The obtained fiber aerogel material is placed in an air environment and heated for 40 minutes at 90°C. Under the action of the crosslinking agent, the fibers are crosslinked with each other, thereby improving the stability of the three-dimensional spatial structure;

[0076] 4) In situ growth of hydrated nanosilicate particles: The cross-linked fiber aerogel is placed in a hydrated nanosilicate particle growth solution and soaked for 6 hours. The volume ratio of the hollow fiber and the hydrated nanosilicate particle growth solution is controlled at 1:10. Figure 4 As shown, the nano-silicate particles begin to grow along the fiber surface and eventually completely cover the fiber surface of the aerogel, forming an inorganic fireproof layer and improving the mechanical properties of the aerogel.

[0077] The raw materials for preparing the growth liquid are polyvinyl alcohol (PVA, the molecular weight of polyvinyl alcohol is 180,000 to 220,000), Ca(NO3)2·4H2O, Na2SiO3·9H2O and Al(NO3)3·9H2O; the preparation method is as follows: 15g PVA is dissolved in 100g deionized water and magnetically stirred at 90°C for 1h; then, 60g Ca(NO3)2 solution (concentration 1mol / L) is added to the PVA solution for cross-linking; next, 50g Na2SiO3 (concentration 1mol / L) and 15g Al(NO3)3 (concentration 1mol / L) solutions are added successively to generate in-situ Ca-Al-Si-H nanoparticles. Before adding Na2SiO3 and Al(NO3)3, the hollow fiber aerogel material after thermal cross-linking treatment has been immersed in the growth liquid. After adding Na2SiO3 and Al(NO3)3, nanoparticles are generated in situ. The chemical equation can be expressed as: Ca 2+ +SiO 2- +3Al 3+ +H2O→(CaO) x (Al2O3)SiO2(H2O) y , and the transparent solution gradually turned milky white with the addition of sodium silicate, which means that Ca-Al-Si-H nanoparticles were generated. The above operation was carried out at room temperature;

[0078] 5) Drying: Drying in an environment of 80° C. until the moisture is completely removed to obtain a hollow fiber aerogel material.

[0079] Example 4

[0080] The main difference between this embodiment and embodiment 1 is that the molecular weight of the polyvinyl alcohol is 100,000 to 150,000.

[0081] Example 5

[0082] The main difference between this embodiment and embodiment 1 is that, in step 3), the thermal crosslinking treatment operation is to place the obtained fiber aerogel material in an air environment at 60° C. and heat it for 60 minutes.

[0083] Example 6

[0084] The main difference between this embodiment and embodiment 1 is that the thermal crosslinking treatment in step 3) is to place the obtained fiber aerogel material in an air environment at 100° C. and heat it for 60 minutes.

[0085] Example 7

[0086] The main difference between this embodiment and embodiment 1 is that the perfusion speed of the skin layer syringe is 6 ml / h, and the perfusion speed of the core layer syringe is 4 ml / h.

[0087] Example 8

[0088] The main difference between this embodiment and embodiment 1 is that the perfusion rate of the skin layer syringe is 2 ml / h, and the perfusion rate of the core layer syringe is 2 ml / h.

[0089] Comparative Example 1

[0090] Compared with Example 1, the main difference between this comparative example and Example 1 is that the amounts of polyvinyl alcohol, calcium nitrate, sodium silicate and aluminum nitrate in the growth solution are different. Specifically, the raw materials for preparing the growth solution are polyvinyl alcohol (PVA, the molecular weight of polyvinyl alcohol is 180,000 to 220,000), Ca(NO3)2·4H2O, Na2SiO3·9H2O and Al(NO3)3·9H2O; the preparation method is as follows: 10g of PVA is dissolved in 100g of deionized water and magnetically stirred at 90°C for 1h; then, 50g of Ca(NO3)2 solution (concentration 1mol / L) is added to the PVA solution for cross-linking; next, 20g of Na2SiO3 (concentration 1mol / L) and 30g of Al(NO3)3 (concentration 1 mol / L) solution was added to generate in situ Ca-Al-Si-H nanoparticles. Before adding Na2SiO3 and Al(NO3)3, the hollow fiber aerogel material after heat cross-linking treatment was immersed in the growth solution. After adding Na2SiO3 and Al(NO3)3, nanoparticles were generated in situ. The chemical equation can be expressed as: Ca 2+ +SiO 2- +3Al 3+ +H2O→(CaO) x (Al2O3)SiO2(H2O) y , and the transparent solution gradually turned milky white with the addition of sodium silicate, which means that Ca-Al-Si-H nanoparticles were generated. The above operation was carried out at room temperature.

[0091] Comparative Example 2

[0092] Compared with Example 1, the main difference between this comparative example and Example 1 is that the amounts of polyvinyl alcohol, calcium nitrate, sodium silicate and aluminum nitrate in the growth solution are different. Specifically, the raw materials for preparing the growth solution are polyvinyl alcohol (PVA, the molecular weight of polyvinyl alcohol is 180,000 to 220,000), Ca(NO3)2·4H2O, Na2SiO3·9H2O and Al(NO3)3·9H2O; the preparation method is as follows: 10g of PVA is dissolved in 100g of deionized water and magnetically stirred at 90°C for 1h; then, 30g of Ca(NO3)2 solution (concentration 1mol / L) is added to the PVA solution for cross-linking; next, 30g of Na2SiO3 (concentration 1mol / L) and 40g of Al(NO3)3 (concentration 1 mol / L) solution was added to generate in situ Ca-Al-Si-H nanoparticles. Before adding Na2SiO3 and Al(NO3)3, the hollow fiber aerogel material after heat cross-linking treatment was immersed in the growth solution. After adding Na2SiO3 and Al(NO3)3, nanoparticles were generated in situ. The chemical equation can be expressed as: Ca 2+ +SiO 2- +3Al 3+ +H2O→(CaO) x (Al2O3)SiO2(H2O) y , and the transparent solution gradually turned milky white with the addition of sodium silicate, which means that Ca-Al-Si-H nanoparticles were generated. The above operation was carried out at room temperature.

[0093] Comparative Example 3

[0094] Compared with Example 1, the main difference between this comparative example and Example 1 is that the amounts of polyvinyl alcohol, calcium nitrate, sodium silicate and aluminum nitrate in the growth solution are different. Specifically, the raw materials for preparing the growth solution are polyvinyl alcohol (PVA, the molecular weight of polyvinyl alcohol is 180,000 to 220,000), Ca(NO3)2·4H2O, Na2SiO3·9H2O and Al(NO3)3·9H2O; the preparation method is as follows: 5g of PVA is dissolved in 100g of deionized water and magnetically stirred at 90°C for 1h; then, 30g of Ca(NO3)2 solution (concentration 1mol / L) is added to the PVA solution for cross-linking; next, 60g of Na2SiO3 (concentration 1mol / L) and 15g of Al(NO3)3 (concentration 1 mol / L) solution was added to generate in situ Ca-Al-Si-H nanoparticles. Before adding Na2SiO3 and Al(NO3)3, the hollow fiber aerogel material after heat cross-linking treatment was immersed in the growth solution. After adding Na2SiO3 and Al(NO3)3, nanoparticles were generated in situ. The chemical equation can be expressed as: Ca 2+ +SiO 2- +3Al 3++H2O→(CaO) x (Al2O3)SiO2(H2O) y , and the transparent solution gradually turned milky white with the addition of sodium silicate, which means that Ca-Al-Si-H nanoparticles were generated. The above operation was carried out at room temperature.

[0095] Test Case

[0096] The performance tests were conducted on the products obtained in Examples 1 to 6 and Comparative Examples 1 to 3, and the results are shown in Table 1 below.

[0097] Thermal coefficient test: Use a thermal conductivity meter to test according to GB / T10294-2008 "Determination of steady-state thermal resistance and related properties of thermal insulation materials". The lower the thermal conductivity, the better the thermal insulation performance.

[0098] Flame retardant test: Use a building material non-combustibility test furnace and conduct tests in accordance with GB 8624 "Classification of Combustion Performance of Building Materials and Products". Building insulation materials are divided into Class A (non-combustible), Class B1 (difficult to burn), Class B2 (combustible), and Class B3 (combustible) according to their combustion performance. Class A is divided into Class A1 and Class A2, with Class A being the best.

[0099] Porosity: Use a mercury intrusion porosimeter to test according to GB / T 21650.1-2008 "Determination of pore size distribution and porosity of solid materials by mercury intrusion and gas adsorption method Part 1: Mercury intrusion method". The larger the porosity, the better the thermal insulation performance.

[0100] Bulk density: Use the geometric measurement method and test according to GB / T 17657-2013 "Test methods for physical and chemical properties of wood-based panels and veneered wood-based panels". The higher the bulk density, the greater the compressive strength, but the lower the porosity, the lower the thermal insulation performance.

[0101] Compressive strength: Use a universal testing machine and test according to GBT8813-1988-Hard Foam Plastic Compression Test Method. The greater the compressive strength, the stronger the ability to resist pressure deformation.

[0102] Table 1 Product performance test results

[0103]

[0104] The results in Table 1 indicate that the aerogel composite material provided by the present application exhibits the comprehensive advantages of lightweight material, efficient thermal insulation, Class A flame retardancy, and high mechanical strength, making it suitable for construction applications. Examples 7 and 8 failed to spin due to inappropriate infusion speed parameter settings. In Example 7, due to excessive flow rates, a large number of polymer droplets were present, while in Example 8, due to a high air flow ratio, the polymer was unable to encapsulate the air and complete spinning.

[0105] The foregoing is merely an embodiment of the present application, and the scope of protection of the present application is not limited by these specific embodiments, but is determined by the claims of the present application. For those skilled in the art, the present application may have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc. made within the technical ideas and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A method for preparing a flame retardant and heat insulating aerogel composite material, characterized in that: The preparation method comprises the following steps: S1. Preparing a spinning solution: dissolving a polymer material in an organic solvent and stirring to dissolve the polymer material, and then adding a cross-linking agent to obtain a polymer material solution for use; S2. Coaxial electrospinning to prepare fiber aerogel: Connect a syringe containing a polymer spinning solution to the skin layer needle tube connection port, and connect a syringe containing air to the core layer needle tube connection port. Coaxial electrospinning is performed to prepare micron fibers with a skin-core structure. The micron fibers fall onto a receiving substrate to obtain a hollow fiber aerogel material with a three-dimensional fluffy structure. S3, thermal crosslinking treatment: heating the obtained hollow fiber aerogel material to perform crosslinking; S4. In-situ growth of hydrated nanosilicate particles: placing the cross-linked hollow fiber aerogel material in a hydrated nanosilicate particle growth solution, so that the nanosilicate particles grow along the fiber surface and cover the micron fiber surface of the hollow fiber aerogel material; S5, obtaining the aerogel composite material after drying; The hydrated nano-silicate particle growth liquid comprises polyvinyl alcohol, calcium nitrate, sodium silicate and aluminum nitrate, and the mass ratio of the polyvinyl alcohol, calcium nitrate, sodium silicate and aluminum nitrate is (5-15): (40-60): (30-50): (5-15).

2. The method for preparing the flame-retardant and heat-insulating aerogel composite material according to claim 1, characterized in that: The preparation method of the hydrated nano-silicate particle growth liquid comprises: 1) dissolving polyvinyl alcohol in deionized water; 2) adding calcium nitrate solution for cross-linking; 3) adding sodium silicate solution and aluminum nitrate solution to generate in situ Ca-Al-Si-H nanoparticles.

3. The method for preparing the flame-retardant and heat-insulating aerogel composite material according to claim 2, characterized in that: The molecular weight of the polyvinyl alcohol is 180,000 to 220,000.

4. The method for preparing the flame-retardant and heat-insulating aerogel composite material according to claim 1, characterized in that: The cross-linking condition of step S3 is 70-90° C. for 40-80 min.

5. The method for preparing the flame-retardant and heat-insulating aerogel composite material according to claim 1, characterized in that: In the coaxial electrospinning technology of step S2, the spinning voltage is 15-25 kV, the spinning distance is 15-25 cm, the receiving drum speed is 30-70 rpm, the perfusion speed of the cortical syringe is 1-4 ml / h, the perfusion speed of the core layer syringe is 0.5-2 ml / h, the ambient temperature is 25±2°C, and the ambient relative humidity is 70-90%.

6. The method for preparing the flame-retardant and heat-insulating aerogel composite material according to claim 1, characterized in that: The polymer material in step S1 is one or both of polysulfone and polystyrene; optionally, the concentration of the polymer material in the polymer material solution in step S1 is 18-22 wt%; optionally, the molecular weight of the polysulfone is 60,000-80,000; optionally, the molecular weight of the polystyrene is 300,000-400,000.

7. The method for preparing the flame-retardant and heat-insulating aerogel composite material according to claim 1, characterized in that: The organic solvent in step S1 is one or more of dimethylformamide, dimethylacetamide, acetone, polymethyl sulfoxide, and tetrahydrofuran.

8. The method for preparing the flame-retardant and heat-insulating aerogel composite material according to claim 1, characterized in that: In step S1, the cross-linking agent is one or more of aziridine, dicumyl peroxide and benzoyl peroxide; optionally, the concentration of the cross-linking agent in the polymer material solution is 5 to 15 wt%.

9. An aerogel composite material prepared by the method for preparing a flame-retardant and heat-insulating aerogel composite material according to any one of claims 1 to 8.

10. Use of the aerogel composite material according to claim 9 in building materials.

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