A flame-retardant, thermal-insulating aerogel composite material, and a preparation method and application thereof

Abstract

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

Description

Technical Field

[0001] This application relates to a flame-retardant and heat-insulating aerogel composite material, its preparation method, and its application, belonging to the field of new building materials technology. Background Technology

[0002] Data shows that about 40% of global energy consumption comes from building operations, with HVAC systems accounting for the highest proportion of energy consumption. In the building envelope, heat loss from walls and roofs alone accounts for 40% of the total heat transfer. Therefore, developing 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 with lightweight, high strength and excellent thermal insulation performance.

[0003] Aerogels are defined as nanoporous solid materials formed by the random cross-linking of nanoparticles or polymer molecules in three-dimensional space, and are a special form of solid matter. Aerogels possess characteristics such as low density, high specific surface area, and high porosity, making them lightweight porous nanomaterials with many excellent properties and wide applications, thus demonstrating great value in many fields.

[0004] Existing patent CN 113683812 A discloses a flame-retardant and heat-insulating polyimide nanofiber aerogel and its preparation method. First, polyamic acid is prepared by polycondensation of polyacid anhydride and polyamine. Then, a silica precursor is added to it. The polyamic acid / silica nanofiber membrane is obtained by electrospinning and hydrolysis. Then, the nanofibers are dispersed in a solvent and prepared by freeze-drying to obtain polyamic acid / silica nanofiber aerogel. Finally, the nanofibers are subjected to high-temperature thermal imidization treatment to obtain a PI nanofiber aerogel with a silica layer on the surface of the nanofibers.

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

[0006] Existing patent CN 107190365 A discloses a silica aerogel composite fiber and its preparation method, including the following steps: preparing silica wet gel; mixing silica wet gel with organic solvent at a volume ratio of 1:(8-30), and then adding crosslinking agent solution to carry out crosslinking reaction to obtain a spinning solution with a concentration of 0.5-1.5 g / mL; electrospinning the spinning solution and drying it under normal pressure to obtain bubbly silica aerogel composite fiber, wherein the crosslinking agent solution is prepared by mixing hydroxyl silicone oil, polyacrylic acid, and organic solvent at a mass ratio of 1:(1-10):(1-30).

[0007] Existing patent CN 120041956 A discloses an aerogel composite fiber flame-retardant thermal insulation material and its preparation method and application, comprising 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 microspheres, and 0.9-3.2 parts of crosslinking agent; the SiO2 aerogel particles and inorganic flame retardant are encapsulated inside the aerogel composite fiber flame-retardant thermal insulation material, and the Al2O3 microspheres are loaded on the surface of the aerogel composite fiber flame-retardant thermal insulation material.

[0008] The technical solution in CN 107190365 A mixes silica wet gel with spinning solution and then spins it. After drying, it prepares composite fibers containing silica aerogel. Each organic fiber contains silica aerogel particles and does not form a three-dimensional fiber stacking structure. It is not a fiber aerogel, which means that its thermal insulation performance, fire resistance and high temperature resistance still have room for improvement.

[0009] The prior patent CN 120041956 A directly adds ready-made aerogel particles as functional additives to the spinning solution to prepare composite fibers, and then loads inorganic particles on the surface of the composite fibers. Because this method adds a lot of powder and particles, the spinning is more difficult, and there may be a phenomenon of the loaded inorganic particles falling off.

[0010] Therefore, it is necessary to provide a new type of flame-retardant and heat-insulating aerogel composite material to solve the problems of existing flame-retardant and heat-insulating building materials. Summary of the Invention

[0011] To address the aforementioned issues, a flame-retardant and heat-insulating aerogel composite material, its preparation method, and its application are provided. The method involves preparing a core-sheath structured micron-fiber aerogel via coaxial electrospinning, followed by thermal cross-linking treatment, and then in-situ growth of hydrated nano-silicate particles. This allows the nano-silicate particles to grow along the fiber surface and cover the micron-fiber surface of the hollow fiber aerogel material. The resulting aerogel composite material exhibits excellent flame-retardant and heat-insulating properties, making it suitable for use as a building material.

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

[0013] S1. Preparation of spinning solution: Dissolve the polymer material in an organic solvent and stir to dissolve. Then add a crosslinking agent to obtain a polymer material solution for later use.

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

[0015] S3. Thermal crosslinking treatment: The obtained hollow fiber aerogel material is heated to crosslink;

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

[0017] S5. After drying, the aerogel composite material is obtained;

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

[0019] Compared with existing technologies, this application utilizes coaxial electrospinning to prepare hollow fiber aerogel composite materials. The hollow fiber structure and aerogel spatial structure endow the material with 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 resistance, while greatly improving the mechanical properties of the material.

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

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

[0022] 2) Add calcium nitrate solution to perform cross-linking;

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

[0024] Optionally, the molecular weight of the polyvinyl alcohol is 180,000 to 220,000. Polyvinyl alcohol with this molecular weight has a high degree of polymerization. The higher the degree of polymerization, the higher the viscosity of the aqueous solution, which improves the strength and solvent resistance of the film after formation. However, if the molecular weight is too high, the solution viscosity will be too high, making it difficult to use; while if the molecular weight is too low, the viscosity will be too low, which is not conducive to the loading of nanoparticles during in-situ growth.

[0025] Optionally, the crosslinking conditions in step S3 are a reaction at 70–90°C for 40–80 minutes. These crosslinking conditions are mild and moderate, avoiding the problems of ineffectiveness or poor results due to excessively low temperatures, as well as the problems of over-crosslinking and damage to the fiber material due to excessively high temperatures.

[0026] Optionally, in the coaxial electrospinning technology of step S2: the spinning voltage is 15-25kV, the spinning distance is 15-25cm, the receiving roller speed is 30-70rpm, the infusion rate of the sheath injector is 1-4ml / h, the infusion rate of the core injector is 0.5-2ml / h, the ambient temperature is 25±2℃, and the relative humidity is 70-90%. The infusion rates of the sheath and core layers affect the formation of the sheath-core structure; the above processing parameters can achieve a better sheath-core structure formation effect. Ambient humidity affects the formation of the three-dimensional fluffy structure; low humidity results in a lack of fluffiness, while humidity above 90% causes the fibers to solidify too quickly, leading to poor forming results.

[0027] Optionally, the infusion rate of the cortical syringe is at least 1.5 times that of the core syringe;

[0028] Optionally, the infusion rate of the cortical syringe is at least twice that of the core 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 for receiving hollow fiber aerogel materials; those skilled in the art can choose other materials.

[0030] Optionally, the polymer material in step S1 is one or both of polysulfone or polystyrene. These two materials, as raw materials for fiber preparation, are easy to form a fluffy three-dimensional fiber stacking structure in a high humidity environment, which is beneficial to improving the thermal insulation performance. They have obvious advantages over other polymer materials 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 will be low, making it difficult to form fibers. If the concentration is too high, the viscosity of the spinning solution will be too high, making it difficult to spin.

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

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

[0034] The above-mentioned molecular weight range ensures good spinnability during the spinning process. If the molecular weight is too low, the viscosity of the spinning solution will be low, making it difficult to form fibers; if the molecular weight is too high, the viscosity of the spinning solution will be too high, making it 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 crosslinking 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 will be insignificant; if the concentration is too high, it will damage the morphology of the fiber membrane.

[0038] Optionally, in step S4, the cross-linked hollow fiber aerogel material is immersed in a hydrated nano-silicate particle growth solution 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 the 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 before sodium silicate and aluminum nitrate are added, and then sodium silicate and aluminum nitrate are added.

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

[0042] This application provides the application of the aforementioned 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 and heat-insulating aerogel composite material, its preparation method and application, hollow fiber aerogel composite material is prepared by coaxial electrospinning process. The hollow fiber structure and aerogel spatial structure endow the material with excellent thermal insulation performance and low thermal conductivity. By in-situ growth of hydrated nano-calcium aluminum silicate particles, a dense inorganic fireproof protective layer can be formed on the outer layer of the fiber to achieve Class A fire resistance, while greatly improving the mechanical properties of the material.

[0045] 2. The flame-retardant and heat-insulating aerogel composite material, its preparation method and application according to this application, the obtained aerogel composite material has the advantages of lightweight material, high-efficiency heat insulation, Class A flame retardancy and high mechanical strength, which facilitates its construction application in building engineering.

[0046] 3. According to the flame-retardant and heat-insulating aerogel composite material, its preparation method and application, the preparation process of the present application is simple, the aerogel fluffy structure can be achieved without freeze-drying, and Class A fire resistance can be achieved without calcining organic materials into inorganic materials at high temperature, with lower energy consumption.

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

[0048] 5. According to the flame-retardant and heat-insulating aerogel composite material, its preparation method and application, the present application adopts the coaxial electrospinning process combined with the technology of growing hydrated nano-calcium aluminum silicate particles to prepare a flame-retardant and heat-insulating aerogel composite material with excellent performance. At present, no similar products or related reports have been seen. The present application is of great significance to the research of new building materials. Attached Figure Description

[0049] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0050] Figure 1 This is a schematic diagram of the coaxial electrospinning process involved in the embodiments of this application;

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

[0052] Figure 3 This is a schematic diagram of the hollow fiber structure in the hollow fiber aerogel material involved in the embodiments of this application;

[0053] Figure 4 This is a schematic diagram of the growth of hydrated nano-calcium aluminum silicate particles in the aerogel composite material involved in the embodiments of this application. Detailed Implementation

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

[0055] Example 1

[0056] 1) Preparation of spinning solution: Using polysulfone (PSU, molecular weight 60,000 to 80,000) as raw material and dimethylformamide (DMF) as organic solvent, prepare a spinning solution with a polymer mass fraction concentration of 20 wt%, stir magnetically for 4 h, and use aziridine crosslinking agent as crosslinking agent with an addition amount of 10 wt%.

[0057] 2) Preparation of fiber aerogels using coaxial electrospinning technology: Micron-sized fibers with a core-sheath structure are prepared using coaxial electrospinning technology, where the sheath is a high-molecular polymer and the core is air, thus forming a structure similar to... Figure 3 The image shows a fibrous aerogel material with a hollow structure.

[0058] like Figure 1 As shown, the polymer spinning solution was injected into a syringe, which was then connected to the outer layer needle port. An air-filled syringe was connected to the core layer needle port for coaxial electrospinning. Polyester nonwoven fabric was used as the receiving substrate. The spinning voltage was 20kV, the spinning distance was 20cm, the receiving roller speed was 50rpm, the injection rate of the outer layer syringe was 3ml / h, the injection rate of the core layer syringe was 1.5ml / h, the ambient temperature was 25℃, and the relative humidity was 80%. The final result was as shown... Figure 2 The hollow fiber aerogel material shown has a three-dimensional fluffy structure;

[0059] 3) Thermal crosslinking treatment: The obtained fiber aerogel material is heated in an air environment at 80°C for 1 hour. Under the action of the crosslinking agent, the fibers crosslink with each other, which improves the stability of the three-dimensional structure.

[0060] 4) In-situ growth of hydrated nano-silicate particles: The cross-linked fiber aerogel was immersed in the hydrated nano-silicate particle growth solution for 4 hours. The volume ratio of hollow fiber to hydrated nano-silicate particle growth solution was controlled at 1:10. Figure 4 As shown, 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 while improving the mechanical properties of the aerogel.

[0061] The raw materials for preparing the growth solution are polyvinyl alcohol (PVA, with a molecular weight of 180,000–220,000), 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℃ for 1h. Then, 50g of Ca(NO3)2 solution (1mol / L) is added to the PVA solution for crosslinking. Next, 40g of Na2SiO3 (1mol / L) and 10g of Al(NO3)3 (1mol / L) solution are added consecutively to generate in-situ Ca-Al-Si-H nanoparticles. Before adding Na2SiO3 and Al(NO3)3, the thermally crosslinked hollow fiber aerogel material has been immersed in the growth solution. 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 Furthermore, 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: Dry at 80℃ until all moisture is removed to obtain hollow fiber aerogel material.

[0063] Example 2

[0064] 1) Preparation of spinning solution: Using polystyrene (PS, molecular weight 300,000 to 400,000) as raw material and dimethylacetamide (DMAc) as organic solvent, prepare a spinning solution with a polymer mass fraction concentration of 22 wt%, stir magnetically for 5 h, and use dicumyl peroxide as crosslinking agent with an addition amount of 15 wt%.

[0065] 2) Preparation of fiber aerogels using coaxial electrospinning technology: Micron-sized fibers with a core-sheath structure are prepared using coaxial electrospinning technology, where the sheath is a high-molecular polymer and the core is air, thus forming a structure similar to... Figure 3 The image shows a fibrous aerogel material with a hollow structure.

[0066] like Figure 1As shown, the polymer spinning solution was injected into a syringe, which was then connected to the outer layer needle port. An air-filled syringe was connected to the core layer needle port for coaxial electrospinning. Polyester nonwoven fabric was used as the receiving substrate. The spinning voltage was 25kV, the spinning distance was 20cm, the receiving roller speed was 50rpm, the injection rate of the outer layer syringe was 4ml / h, the injection rate of the core layer syringe was 2ml / h, the ambient temperature was 27℃, and the relative humidity was 85%. The final result was as shown... Figure 2 The hollow fiber aerogel material shown has a three-dimensional fluffy structure;

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

[0068] 4) In-situ growth of hydrated nano-silicate particles: The cross-linked fiber aerogel was immersed in the growth solution of hydrated nano-silicate particles for 3 hours. The volume ratio of hollow fiber to hydrated nano-silicate particle growth solution was controlled at 1:10. Figure 4 As shown, 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 while improving the mechanical properties of the aerogel.

[0069] The raw materials for preparing the growth solution are polyvinyl alcohol (PVA, with a molecular weight of 180,000–220,000), 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℃ for 1h. Then, 40g of Ca(NO3)2 solution (1mol / L) is added to the PVA solution for crosslinking. Next, 30g of Na2SiO3 (1mol / L) and 5g of Al(NO3)3 (1mol / L) solution are added consecutively to generate in-situ Ca-Al-Si-H nanoparticles. Before adding Na2SiO3 and Al(NO3)3, the thermally crosslinked hollow fiber aerogel material has been immersed in the growth solution. 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 Furthermore, 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: Dry at 80℃ until all moisture is removed to obtain hollow fiber aerogel material.

[0071] Example 3

[0072] 1) Preparation of spinning solution: Using polysulfone (PSU, molecular weight 60,000 to 80,000) as raw material and tetrahydrofuran (THF) as organic solvent, prepare a spinning solution with a polymer mass fraction concentration of 18wt%, stir magnetically for 3h, and add benzoyl peroxide as crosslinking agent at a rate of 5wt%.

[0073] 2) Preparation of fiber aerogels using coaxial electrospinning technology: Micron-sized fibers with a core-sheath structure are prepared using coaxial electrospinning technology, where the sheath is a high-molecular polymer and the core is air, thus forming a structure similar to... Figure 3 The image shows a fibrous aerogel material with a hollow structure.

[0074] like Figure 1 As shown, the polymer spinning solution was injected into a syringe, which was then connected to the outer layer needle port. An air-filled syringe was connected to the core layer needle port for coaxial electrospinning. Polyester nonwoven fabric was used as the receiving substrate. The spinning voltage was 15kV, the spinning distance was 20cm, the receiving roller speed was 50rpm, the injection rate of the outer layer syringe was 1ml / h, the injection rate of the core layer syringe was 0.5ml / h, the ambient temperature was 23℃, and the relative humidity was 75%. The final result was as shown... Figure 2 The hollow fiber aerogel material shown has a three-dimensional fluffy structure;

[0075] 3) Thermal crosslinking treatment: The obtained fiber aerogel material is heated in an air environment at 90℃ for 40 minutes. Under the action of the crosslinking agent, the fibers crosslink with each other, which improves the stability of the three-dimensional spatial structure.

[0076] 4) In-situ growth of hydrated nano-silicate particles: The cross-linked fiber aerogel was immersed in the hydrated nano-silicate particle growth solution for 6 hours. The volume ratio of hollow fiber to hydrated nano-silicate particle growth solution was controlled at 1:10. Figure 4 As shown, 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 while improving the mechanical properties of the aerogel.

[0077] The raw materials for preparing the growth solution are polyvinyl alcohol (PVA, with a molecular weight of 180,000–220,000), Ca(NO3)2·4H2O, Na2SiO3·9H2O, and Al(NO3)3·9H2O. The preparation method is as follows: 15g of PVA is dissolved in 100g of deionized water and magnetically stirred at 90℃ for 1h. Then, 60g of Ca(NO3)2 solution (1mol / L) is added to the PVA solution for crosslinking. Next, 50g of Na2SiO3 (1mol / L) and 15g of Al(NO3)3 (1mol / L) solution are added consecutively to generate in-situ Ca-Al-Si-H nanoparticles. Before adding Na2SiO3 and Al(NO3)3, the thermally crosslinked hollow fiber aerogel material has been immersed in the growth solution. 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 Furthermore, 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: Dry at 80℃ until all moisture is removed to obtain hollow fiber aerogel material.

[0079] Example 4

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

[0081] Example 5

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

[0083] Example 6

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

[0085] Example 7

[0086] The main difference between this embodiment and Embodiment 1 is that the infusion rate of the cortical syringe is 6 ml / h, and the infusion rate of the core syringe is 4 ml / h.

[0087] Example 8

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

[0089] Comparative Example 1

[0090] The main difference between this comparative example and Example 1 lies in the different amounts of polyvinyl alcohol, calcium nitrate, sodium silicate, and aluminum nitrate used in the growth solution. Specifically, the raw materials for the growth solution are polyvinyl alcohol (PVA, with a molecular weight of 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 1 hour; then, 50g of Ca(NO3)2 solution (concentration 1mol / L) is added to the PVA solution for crosslinking; next, 20g of Na2SiO3 (concentration 1mol / L) and 30g of... In 1 mol / L Al(NO3)3 solution, in-situ Ca-Al-Si-H nanoparticles are generated. Before adding Na2SiO3 and Al(NO3)3, the thermally cross-linked hollow fiber aerogel material was immersed in the growth solution. 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 Furthermore, 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] The main difference between this comparative example and Example 1 lies in the different amounts of polyvinyl alcohol, calcium nitrate, sodium silicate, and aluminum nitrate used in the growth solution. Specifically, the raw materials for the growth solution are polyvinyl alcohol (PVA, with a molecular weight of 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 1 hour; then, 30g of Ca(NO3)2 solution (concentration 1mol / L) is added to the PVA solution for crosslinking; next, 30g of Na2SiO3 (concentration 1mol / L) and 40g of... In 1 mol / L Al(NO3)3 solution, in-situ Ca-Al-Si-H nanoparticles are generated. Before adding Na2SiO3 and Al(NO3)3, the thermally cross-linked hollow fiber aerogel material was immersed in the growth solution. 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 Furthermore, 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] The main difference between this comparative example and Example 1 is the amount of polyvinyl alcohol, calcium nitrate, sodium silicate, and aluminum nitrate used in the growth solution. Specifically, the raw materials for the growth solution are polyvinyl alcohol (PVA, with a molecular weight of 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 crosslinking; next, 60g of Na2SiO3 (concentration 1mol / L) and 15g of... In 1 mol / L Al(NO3)3 solution, in-situ Ca-Al-Si-H nanoparticles are generated. Before adding Na2SiO3 and Al(NO3)3, the thermally cross-linked hollow fiber aerogel material was immersed in the growth solution. 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 Furthermore, 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] Performance tests were conducted on the products obtained in Examples 1-6 and Comparative Examples 1-3, and the results are shown in Table 1 below.

[0097] Thermal conductivity test: The test is conducted using a thermal conductivity meter in accordance with 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: The non-combustible building materials test furnace is used to conduct the test according to GB 8624 "Classification of Combustion Performance of Building Materials and Products". Building insulation materials are classified into Class A (non-combustible), Class B1 (flame-retardant), Class B2 (combustible), and Class B3 (flammable) according to their combustion performance. Class A is further divided into A1 and A2, with A1 being the best.

[0099] Porosity: The porosity was tested using a mercury porosimeter in accordance with GB / T 21650.1-2008 "Determination of pore size distribution and porosity of solid materials by mercury porosimeter and gas adsorption method - Part 1: Mercury porosimeter method". The higher the porosity, the better the thermal insulation performance.

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

[0101] Compressive strength: Tested using a universal testing machine according to "GBT8813-1988-Rigid Foamed Plastics 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] As shown in Table 1, the aerogel composite material provided by this application possesses excellent comprehensive properties, including lightweight, high-efficiency thermal insulation, Class A flame retardancy, and high mechanical strength, making it suitable for construction applications in building engineering. However, Examples 7 and 8 failed to spin due to inappropriate infusion speed parameters. In Example 7, the flow rate was too high, resulting in numerous polymer droplets, while in Example 8, the high air flow ratio prevented the polymer from encapsulating air and completing the spinning process.

[0105] The above description is merely an embodiment of this application, and the scope of protection of this application is not limited to these specific embodiments, but is determined by the claims of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the technical concept and principles of this application should be included within the scope of protection of this application.

Claims

1. A method for preparing a flame-retardant, thermally- insulating aerogel composite material, characterized in that, The preparation method comprises the following steps: S1, configuring a spinning solution: dissolving a polymer material in an organic solvent and stirring to dissolve, then adding a crosslinking agent to obtain a polymer material solution for standby; S2, coaxial electrospinning to prepare a fiber aerogel: connecting a syringe containing a polymer spinning solution to a skin layer needle tube connection port, connecting a syringe containing air to a core layer needle tube connection port, and performing coaxial electrospinning to prepare a micron fiber with a skin-core structure, the micron fiber falling on a receiving substrate to obtain a hollow fiber aerogel material with a three-dimensional fluffy structure; S3, heat crosslinking treatment: heating the obtained hollow fiber aerogel material for crosslinking; S4, in-situ growth of hydrated nanosilicate particles: placing the crosslinked 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, drying to obtain the aerogel composite material; The hydrated nanosilicate particle growth solution 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); the preparation method of the hydrated nanosilicate particle growth solution comprises the following steps: 1) dissolving polyvinyl alcohol in deionized water; 2) adding a calcium nitrate solution for crosslinking; 3) adding a sodium silicate solution and an aluminum nitrate solution to generate in-situ Ca-Al-Si-H nanoparticles; In the step S2 coaxial electrospinning technology: the spinning voltage is 15-25 kV, the spinning distance is 15-25 cm, the receiving drum rotating speed is 30-70 rpm, the filling speed of the skin layer syringe is 1-4 ml / h, the filling speed of the core layer syringe is 0.5-2 ml / h, the environmental temperature is 25±2 ℃, and the environmental relative humidity is 70-90%; The polymer material in the step S1 is one or both of polysulfone and polystyrene; and the concentration of the polymer material in the polymer material solution in the step S1 is 18-22 wt%.

2. The method of producing a flame retarded, thermally insulated aerogel composite material according to claim 1, characterized in that, The molecular weight of the polyvinyl alcohol is 180-220 thousand.

3. The method of producing a flame retarded, thermally insulated aerogel composite material according to claim 1, characterized in that, The crosslinking condition of the step S3 is 70-90 ℃ for 40-80 min.

4. The method of producing a flame retarded, thermally insulated aerogel composite material according to claim 1, characterized in that, The molecular weight of the polysulfone is 60-80 thousand.

5. The method of producing a flame retarded, thermally insulated aerogel composite material according to claim 1, characterized in that, The molecular weight of the polystyrene is 300-400 thousand.

6. The method of producing a flame retarded, thermally insulated aerogel composite material according to claim 1, characterized in that, The organic solvent in the step S1 is one or more of dimethylformamide, dimethylacetamide, acetone, polymethyl sulfoxide and tetrahydrofuran.

7. The method of producing a flame retarded, thermally insulated aerogel composite material according to claim 1, characterized in that, The crosslinking agent in the step S1 is one or more of aziridine, dicumyl peroxide and benzoyl peroxide.

8. The method of producing a flame retarded, thermally insulated aerogel composite material according to claim 7, characterized in that, The concentration of the crosslinking agent in the polymer material solution is 5-15 wt%.

9. The aerogel composite material prepared by the preparation method of the flame-retardant and heat-insulating aerogel composite material according to any one of claims 1-8.

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

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