Self-expanding aerogel microsphere / colloidal particle, composite material and preparation method of self-expanding aerogel microsphere / colloidal particle

Abstract

The invention belongs to the field of composite materials, and particularly relates to self-expanding aerogel microspheres / colloidal particles, a composite material and a preparation method of the self-expanding aerogel microspheres / colloidal particles. The self-expanding aerogel microspheres / colloidal particles are prepared by taking macromolecules and a flame retardant as raw materials. And then mixing the self-expanding aerogel microspheres / colloidal particles with a base material to prepare the composite material. The composite material disclosed by the invention has good flame-retardant and heat-insulating properties.

Description

Technical Field

[0001] The present invention belongs to the field of composite materials, and particularly relates to a self-expanding aerogel microsphere / granule, a composite material and a preparation method thereof. Background Art

[0002] Global warming has become a global issue. Polymer materials such as foams, resins, and films are widely used in fields such as furniture, transportation, construction, electronics, and aerospace. However, due to the large amount of C-H segments in their molecular structures, they are extremely flammable, and fires caused thereby are not uncommon. With the improvement of the living standards of mankind, the requirements for the flame retardancy of foam, resin, and film products are getting higher and higher. Therefore, developing materials with excellent thermal insulation and flame retardancy has important research value and strategic significance.

[0003] The use of polymer flame retardant technology can reduce the fire risk of substrates. Compared with reactive flame retardants, additive flame retardants have the advantages of simple operation, low cost, and being more suitable for industrial production, and have been widely used. Traditional halogen-containing flame retardants have high flame retardancy efficiency, but they have biological toxicity and environmental accumulation, and have gradually been banned by many countries in the world. Currently, halogen-free flame retardants are divided into: (1) gas-phase flame retardancy; (2) condensed-phase flame retardancy. Most of the gas-phase flame retardants represented by phosphonates are obtained by synthetic means, and the synthesis steps are complex, and their applications will be greatly limited. For the condensed-phase flame retardancy mainly based on expandable graphite (EG), although the expansion flame retardancy effect is very good, the formed carbon presents a discrete worm-like shape, and the flame retardancy efficiency is ultimately limited. For the condensed-phase flame retardancy mainly based on phosphorus-nitrogen flame retardants, most of them are still mainly based on synthesis, and the flame retardancy effect is not outstanding compared with EG. Moreover, currently, phosphorus-containing flame retardants are often used in combination with EG for synergistic flame retardancy to reduce the EG addition amount; or the surface of EG is modified to improve its compatibility; however, the problem of EG destroying the cell structure of the substrate still exists, and it is still difficult to maintain the original thermal insulation performance of the substrate. Currently, there are few reports on the work of highly efficient condensed-phase flame retardancy in the non-EG system, and the contradiction between the high flame retardancy performance and the thermal insulation performance of the substrate is difficult to effectively solve.

[0004] Therefore, developing a material with good compatibility, good flame retardancy effect, and excellent thermal insulation performance has important application value. Summary of the Invention

[0005] Aiming at the above defects, the present invention first provides a self-expanding aerogel microsphere / granule and a preparation method thereof. Then, the self-expanding aerogel microsphere / granule is added to a substrate to prepare a composite material with flame retardant and thermal insulation effects.

[0006] The technical solution of the present invention:

[0007] The present invention provides a method for preparing self - expanding aerogel microspheres / granules. The preparation method includes the following steps: mixing raw material A, a flame retardant and a solvent to prepare a precursor solution, granulating the precursor solution in an environment below - 5 °C to form droplet microspheres / granules, and then removing the ice crystal water in the droplet microspheres / granules to obtain the self - expanding aerogel microspheres / granules; the raw material A is a polymer or the raw material A is a polymer and a cross - linker.

[0008] Specifically, in the above - mentioned method for preparing self - expanding aerogel microspheres / granules, the polymer is selected from one or more of chitosan, starch, gelatin (PG / FG), cellulose, carboxymethyl cellulose, cellulose acetate, lignin, pectin, gellan gum, carboxymethyl chitosan, polyvinyl alcohol, polyacrylic acid, polydopamine, phenolic resin, melamine - formaldehyde resin, soy protein isolate, polyacrylamide, guar gum.

[0009] Specifically, in the above - mentioned method for preparing self - expanding aerogel microspheres / granules, the cross - linker is selected from one or more of hydroxymethylated melamine, hydroxymethylated phenol, glutaraldehyde, formaldehyde, divalent copper salts, divalent nickel salts.

[0010] Specifically, in the above - mentioned method for preparing self - expanding aerogel microspheres / granules, the flame retardant is selected from one or more of trimethylolphosphine oxide, ammonium polyphosphate, red phosphorus, phytic acid, aminotrimethylenephosphonic acid, phenylphosphonic acid, sodium phytate, aluminum hypophosphite, melamine cyanurate, magnesium hydroxide, aluminum hydroxide.

[0011] Further, in the above - mentioned method for preparing self - expanding aerogel microspheres / granules, the raw material A can be selected from the following systems:

[0012] Gelatin and hydroxymethylated melamine; pectin and hydroxymethylated melamine; gelatin; gellan gum and hydroxymethylated phenol; polyacrylamide and glutaraldehyde; carboxymethyl cellulose and glutaraldehyde; polydopamine and divalent copper salts (such as basic copper carbonate, CuCO3·Cu(OH)2); carboxymethyl chitosan; polyvinyl alcohol and formaldehyde; soy protein isolate and hydroxymethylated melamine; phenolic resin; melamine - formaldehyde resin and divalent copper salts (such as basic copper carbonate, CuCO3·Cu(OH)2); starch and hydroxymethylated melamine; lignin and divalent copper salts (such as basic copper carbonate, CuCO3·Cu(OH)2); guar gum; chitosan and hydroxymethylated melamine.

[0013] Furthermore, in the above - mentioned method for preparing self - expanding aerogel microspheres / granules, the raw material A and the flame retardant can be selected from the following systems:

[0014] Gelatin, hydroxymethylated melamine, and phosphorous acid, trimethylol; Pectin, hydroxymethylated melamine, and aminotrimethylene phosphonic acid; Gelatin and phytic acid; Gellan gum, hydroxymethylated phenol, and sodium phytate; Polyacrylamide, glutaraldehyde, and magnesium hydroxide; Carboxymethyl cellulose, glutaraldehyde, and aluminum hydroxide; Polydopamine, divalent copper salt (such as basic copper carbonate, CuCO3·Cu(OH)2), and melamine cyanurate; Hydroxymethyl chitosan and ammonium polyphosphate; Polyvinyl alcohol, formaldehyde, and phenylphosphonic acid; Gelatin, hydroxymethylated melamine, and aminotrimethylene phosphonic acid; Soybean protein isolate, hydroxymethylated melamine, and aminotrimethylene phosphonic acid; Gelatin and phytic acid; Phenolic resin and ammonium polyphosphate; Melamine formaldehyde resin, divalent copper salt (such as basic copper carbonate, CuCO3·Cu(OH)2), and phytic acid; Starch, hydroxymethylated melamine, and magnesium hydroxide; Lignin, divalent copper salt (such as basic copper carbonate, CuCO3·Cu(OH)2), and sodium phytate; Guar gum and phytic acid; Gelatin, hydroxymethylated melamine, and phosphorous acid, trimethylol; Chitosan, hydroxymethylated melamine, and aluminum hypophosphite.

[0015] Preferably, in the method for preparing the self - expanding aerogel microspheres / granules, when raw material A is a polymer and a cross - linker, the mass ratio of the polymer, cross - linker, and flame retardant is 10﹕0.5﹕0.5 to 1﹕1﹕1.

[0016] Preferably, in the method for preparing the self - expanding aerogel microspheres / granules, when raw material A is a polymer, the mass ratio of the polymer and the flame retardant is 10﹕0.5 to 1﹕1.

[0017] Specifically, in the method for preparing the self - expanding aerogel microspheres / granules, the solvent is water.

[0018] Furthermore, in the method for preparing the self - expanding aerogel microspheres / granules, the solid content of the precursor solution is 1 - 20 wt%.

[0019] Specifically, in the method for preparing the self - expanding aerogel microspheres / granules, the environment below - 5°C is selected from liquid nitrogen, liquid helium, cold stage, refrigerator, or freezer.

[0020] Furthermore, in the method for preparing the self - expanding aerogel microspheres / granules, the environment below - 5°C is liquid nitrogen.

[0021] Specifically, in the method for preparing the self - expanding aerogel microspheres / granules, the granulation method is selected from one of manual spraying, ultrasonic spraying, heating spraying, pneumatic spraying, electric spraying, electrospinning spraying, or syringe droplet method.

[0022] Specifically, in the above method for preparing self - expanding aerogel microspheres / granules, the method for removing the ice crystal water in the droplet micro - particles / granules is selected from freeze - drying, vacuum drying, atmospheric drying or supercritical drying.

[0023] The present invention also provides self - expanding aerogel microspheres / granules prepared by the above method for preparing self - expanding aerogel microspheres / granules.

[0024] The present invention also provides a composite material, which is prepared by mixing the above self - expanding aerogel microspheres / granules with a substrate and then processing and forming.

[0025] Furthermore, in the above composite material, the self - expanding aerogel microspheres account for 1 - 40 wt% of the total amount of the self - expanding aerogel microspheres and the substrate.

[0026] Furthermore, in the above composite material, the mass ratio of the self - expanding aerogel granules to the substrate foaming liquid is 1:10 - 10:1.

[0027] Specifically, in the above composite material, the substrate is selected from one of foam, adhesive, and aerogel.

[0028] Furthermore, in the above composite material, the foam is selected from one of polyurethane foam, polystyrene foam, polypropylene foam, and polyimide foam.

[0029] Furthermore, in the above composite material, the processing and forming is selected from one or more of molding foaming, hot - pressing forming, thermosetting forming, and injection molding.

[0030] The beneficial effects of the present invention are as follows:

[0031] The self - expanding aerogel microspheres / granules of the present invention have an excellent cross - linked network structure, and have advantages such as ablation resistance, high flame - retardant performance, self - expanding performance, and wide - temperature - range heat - insulation performance. After the self - expanding aerogel microspheres / granules of the present invention are mixed with the substrate to prepare a composite material, due to the good compatibility of the self - expanding aerogel microspheres / granules, there is an excellent interfacial bond with the substrate, and the physical structure of the substrate itself will not be damaged, thereby improving the mechanical properties of the composite material, and the composite material has good flame - retardant performance and excellent heat - insulation performance. The present invention provides a new idea for improving the flame - retardant performance of materials and coordinating their heat - insulation performance. Description of the Drawings

[0032] Figure 1 It is a scanning electron microscope (SEM) image of the aerogel microspheres and the composite material obtained in Example 1 of the present invention (in the figure, a is the aerogel microspheres, b is the composite material, and c is the composite material after combustion); Figure 1It can be seen that the aerogel microspheres of the present invention are successfully prepared, and they have good compatibility in rigid polyurethane foam. After combustion, it can be clearly observed that the spherical carbon residues generated by the thermal expansion of the porous microspheres indicate excellent expansion effect.

[0033] Figure 2 This is the SEM image of the aerogel particles and the composite material obtained in Example 3 of the present invention (a is the aerogel particles, b is the composite material, and c is the composite material after combustion in the figure); Figure 2 It can be seen that the aerogel particles are successfully prepared by the disposable injection dropping method in the present invention, and they have good interfacial compatibility with rigid polyurethane foam. After combustion, it can be clearly observed that the pores formed by the thermal expansion of the aerogel particles indicate excellent expansion effect.

[0034] Figure 3 This is the digital photo of the butane torch test of the materials obtained in Example 3, Comparative Example 1, and Comparative Example 3 of the present invention (a is the rigid polyurethane foam prepared in Comparative Example 1, b is the bulk aerogel prepared in Comparative Example 3, and c is the bulk aerogel prepared in Example 3 in the figure); Figure 3 It can be seen that the aerogel prepared in the present invention has excellent expansion and flame retardant properties.

[0035] Figure 4 This is the digital photo of the composite material obtained in Example 3 of the present invention; Figure 4 It can be seen that the composite material prepared in the present invention has good formability, exhibits low density, and can stand on the flower.

[0036] Figure 5 This is the digital photo and SEM image of the composite material obtained in Example 4 of the present invention (a is the SEM image of the aerogel particle part, and b is the SEM image of the rigid polyurethane foam part); Figure 5 It can be seen that the composite material prepared in the present invention has good formability, and the pores in both the aerogel and rigid polyurethane foam parts maintain excellent structural integrity.

[0037] Figure 6 This is the digital photo before and after the limiting oxygen index test of the composite materials obtained in Example 4, Comparative Example 1, and Comparative Example 3 of the present invention (a is the rigid polyurethane foam prepared in Comparative Example 1, b is the composite material prepared in Comparative Example 3, and c is the composite material prepared in Example 4); Figure 6 It can be seen that the composite material prepared in the present invention has good formability. After the limiting oxygen index test, the combustion surface of the composite material in Example 4 shows expanded spherical carbon residues, indicating its excellent expansion and flame retardant properties.

[0038] Figure 7 This is the infrared thermal imaging diagram of the composite material obtained in Example 3 of the present invention (a is the infrared thermal imaging diagram of the composite material placed on a constant temperature hot plate at 100 °C, and b is the infrared thermal imaging diagram of the composite material placed on a cold plate with liquid nitrogen as the cold source);Figure 7 It can be seen that after the composite material prepared by the present invention is placed on a constant temperature hot stage at 100 °C for 30 minutes, the upper surface of the material still maintains a relatively low temperature (23.3 °C); after the composite material is placed on a cold plate with liquid nitrogen as the cold source for 30 minutes, the upper surface of the material still maintains a relatively high temperature (20.0 °C); this shows that the composite material has excellent heat insulation and heat preservation performance in both hot and cold environments. Detailed implementation mode

[0039] The present invention provides a method for preparing self-expanding aerogel microspheres / colloids, and the preparation method includes the following steps: configuring raw material A, a flame retardant and a solvent into a precursor solution with a certain solid content, and adding the precursor solution into a -5 °C low-temperature environment by means of spraying or dropping granulation to form droplet microparticles / colloids, and then collecting and transferring the frozen particles to a vacuum freeze dryer, etc. to freeze-dry the ice crystal water in the microparticles / colloids, and finally they can be placed in a vacuum oven for further drying to obtain self-expanding aerogel microspheres / colloids; the raw material A is a polymer or the raw material A is a polymer and a cross-linking agent.

[0040] In the present invention, in order to ensure the uniformity and density of the porous structure of the self-expanding aerogel microspheres / colloids, the interfacial bonding between the aerogel and the substrate and its compatibility in the substrate, as well as the self-expanding performance of the aerogel, the raw materials are polymer and a flame retardant, or polymer, a cross-linking agent and a flame retardant. When the raw materials are polymer, a cross-linking agent and a flame retardant, the mass ratio of the polymer, the cross-linking agent and the flame retardant is 10﹕0.5﹕0.5 to 1﹕1﹕1. When the raw materials are polymer and a flame retardant, the mass ratio of the polymer and the flame retardant is 10﹕0.5 to 1﹕1.

[0041] In the present invention, the solvent can be selected as water or other solvents. To avoid solvent replacement, the preferred solvent is water.

[0042] In the present invention, the solid content in the precursor solution = (total mass of polymer, cross-linking agent and flame retardant) / (total mass of polymer, cross-linking agent, flame retardant and solvent) * 100%.

[0043] In the present invention, the purpose of placing the precursor solution in a -5 °C low-temperature environment is to quickly freeze the water in the formed microparticles or colloids during granulation to form ice crystal water, and realize the preliminary construction and shaping of the three-dimensional structure. This low-temperature environment is usually achieved by using a refrigerant, such as liquid nitrogen, liquid helium, or by using a cold stage, a refrigerator, etc. It is preferably liquid nitrogen. After freezing, vacuum freeze drying, atmospheric drying or supercritical drying, etc. are used to remove the "ice crystal" water, thereby forming a porous structure. Finally, a vacuum oven, etc. can also be used for further drying to remove the un-freeze-dried bound water.

[0044] In the present invention, the aerogel particles prepared by different granulation methods have different particle sizes. For example, the particle size of the aerogel prepared by spraying reaches the micron level and can be called aerogel microspheres; the particle size of the aerogel prepared by the syringe droplet method reaches the millimeter level and can be called aerogel particles. There is no requirement for the particle size of the droplet microparticles / particles. The particle size of the spray granulated aerogel microspheres is generally 0.1 μm to 500 μm, and the particle size of the syringe droplet granulated aerogel particles is generally 1 mm to 10 mm. The spraying includes manual spraying, ultrasonic spraying, heating spraying, pneumatic spraying, electric spraying, and electrospinning spraying. Both the spray granulation method and the syringe granulation method are conventional granulation methods.

[0045] The present invention also provides a composite material prepared by using the above self-expanding aerogel microspheres / particles and a substrate. The preparation method of the composite material includes the following steps: mixing the self-expanding aerogel microspheres / particles prepared above with a substrate foaming solution or each raw material component of the substrate in a certain proportion, and then processing and shaping to obtain the composite material.

[0046] In the present invention, materials with adhesiveness and capable of being cured and shaped by some methods can all be used as substrates, including but not limited to foam materials, adhesives, aerogels, etc.

[0047] In the present invention, the added raw material A functions as a carbon source and a gas source, and the flame retardant functions as an acid source. After the aerogel is heated, the acid source catalyzes the decomposition of the gas source to generate inert gases, and the carbon source dehydrates to form carbon. The three cooperate, and the inert gases are released, blowing up a dense carbon layer to form an expansion effect. The expanded carbon layer has a continuous and dense porous structure and has excellent high-temperature heat insulation performance. It can not only act as a heat insulation layer to slow down the heat transfer process between the combustion area and the substrate, reducing the possibility of further degradation of the polymer to release flammable gases when heated, but also the dense carbon layer can isolate the entry of external oxygen. Therefore, the self-expanding aerogel microspheres / particles can endow the polymer with excellent condensed-phase flame retardant performance and improve the fire safety of the polymer.

[0048] In the following examples of the present invention, the limiting oxygen index was tested on the samples according to the standard GB / T 2046.2-2009; the cone calorimeter test was evaluated according to ISO 5660-1-2015.

[0049] Example 1

[0050] Select the substrate as rigid polyurethane foam:

[0051] 1) Pretreatment: Weigh 35.0 g of melamine, add 67.6 g of formaldehyde solution to it, then add 197.4 g of deionized water to it. Place it in a water bath at 85 °C and react for 1.5 h. During the reaction process, detect the change of the solution pH value, and control the solution pH to 9 - 10 with NaOH. After the reaction, obtain the hydroxymethylated melamine solution (MOH, 20 wt%), put it in the refrigerator and freeze it for two days, then place it in a freeze dryer and freeze-dry it for three days. Take it out and pack it in a plastic-sealed bag.

[0052] 2) Preparation of aerogel microspheres: First, dissolve 6.0 g of gelatin (PG) in 82.0 g of deionized water. Place it in a water bath at 70 °C to completely dissolve the gelatin, then place it on a rotary stirrer. Weigh 6.0 g of MOH and add it to the above system. Then weigh 6.0 g of trimethylolphosphine oxide (THPO) and add it to the above system (the solid content of the precursor solution is 18%). After quickly mixing evenly, transfer it to a pneumatic sprayer and spray it into a container filled with liquid nitrogen. Collect the obtained hydrogel microspheres, place them in a freeze dryer and freeze-dry them for three days. Take out the obtained porous aerogel microspheres, place them in a vacuum oven at 80 °C for 24 h (to remove the un-freeze-dried bound water), take them out and sieve them twice (100 mesh) to obtain ternary integrated self-expanding aerogel microspheres;

[0053] 3) Preparation of composite materials: The formula of rigid polyurethane foam is

[0054]

[0055] Note: 4110 (polyether polyol for rigid foam), H2O (deionized water), A 33 B (triethylenediamine), T 12 (dibutyltin dilaurate), AK-8805 (surfactant), C5H 12 (n-pentane), PMDI (polymethylene polyphenyl isocyanate), php represents the mass per hundred parts of polyether polyol.

[0056] Add 15 php of the aerogel microspheres (6.29 wt%) prepared in step 2) to the mixture of 4110, H2O, A 33 B, T 12 , AK-8805, C5H 12 . After stirring and mixing evenly, add PMDI to it. After mixing evenly, pour it into a mold and wait for foaming to complete. Place it in an oven at 70 °C for thermosetting molding to obtain the composite material.

[0057] The density of this composite material is 76 mg / cm 3 , the limiting oxygen index is 24%, the peak heat release is 278 kW / m 2 , the compression modulus is 11 MPa, the thermal conductivity is 29.8 mW / (m·K), and the pore diameter of the aerogel is 50 nm - 100 nm.

[0058] Example 2

[0059] Select the substrate as rigid polyurethane foam:

[0060] 1) Pretreatment: Weigh 35.0 g of melamine, add 67.6 g of formaldehyde solution to it, then add 197.4 g of deionized water, place it in a water bath at 85 °C and react for 1.5 h. During the reaction process, detect the change of the pH value of the solution, and control the pH of the solution to 9 - 10 with NaOH. After the reaction, obtain the hydroxymethylated melamine solution (MOH, 20 wt%). Put it in the refrigerator and freeze for two days, then put it in a freeze dryer and freeze-dry for three days. Take it out and pack it in a plastic-sealed bag.

[0061] 2) Preparation of aerogel microspheres: First, add 4.0 g of pectin to 65.4 g of deionized water and dissolve it in a water bath at 80 °C. Take another 100 mL dry and clean beaker, add 4.0 g of MOH and 22.6 g of deionized water, dissolve it in a water bath at 70 °C to prepare a solution with a mass fraction of 15%. After the two substances are dissolved and slightly cooled, add the MOH solution to the pectin solution. Then add 4.0 g of aminotrimethylene phosphonic acid (ATMP, 50 wt%) to the pectin solution and stir evenly (the solid content of the precursor solution is 10%). Transfer it to a manual sprayer and spray it into a container filled with liquid nitrogen. Collect the obtained hydrogel microspheres, place them in a freeze dryer and freeze-dry for three days. Take out the freeze-dried aerogel microspheres, place them in a vacuum oven at 80 °C for 24 h (to remove the un-freeze-dried bound water), take them out and sieve twice (100 mesh) to obtain ternary integrated self-expanding aerogel microspheres;

[0062] 3) Preparation of composite material: The formula of rigid polyurethane foam is

[0063]

[0064] Add 20 php (8.14 wt%) of the aerogel microspheres prepared in step 2) to 4110, H2O, A 33 B, T 12 , AK - 8805, C5H 12 mixture. After stirring and mixing evenly, add PMDI to it. After mixing evenly, pour it into a mold and wait for foaming to complete, then place it in an oven at 70 °C for thermosetting molding to obtain the composite material.

[0065] The density of this product is 82 mg / cm 3 , the limiting oxygen index is 24.5%, the peak heat release is 253 kW / m 2 , the compression modulus is 11 MPa, the thermal conductivity is 28.4 mW / (m·K), and the pore size is between 30 nm - 90 nm.

[0066] Example 3

[0067] Select the substrate as rigid polyurethane foam:

[0068] 1) Preparation of aerogel particles: First, dissolve 5.0 g of gelatin (FG) in 62.75 g of deionized water. Place it in a 70 °C water bath until the gelatin (FG) is completely dissolved, then place it on a rotary stirrer. Weigh 1.0 g of phytic acid (PA, 50 wt%) and add it to the above system (the solid content of the precursor solution is 8%). After quickly mixing evenly, use a disposable syringe to drop it into a container filled with liquid nitrogen, collect the obtained hydrogel particles, place them in a freeze dryer and freeze-dry for three days. Take out the freeze-dried porous aerogel particles, place them in a vacuum oven at 80 °C for 24 h (to remove the un-freeze-dried bound water) to obtain ternary integrated self-expanding aerogel particles;

[0069] 2) Preparation of the composite material: The formula of rigid polyurethane foam is

[0070]

[0071] Note: 4110 (polyether polyol for rigid foam), TEOA (triethanolamine), H2O (pure water), AK-8805 (surfactant), C5H 12 (n-pentane), 8154 (delayed catalyst), PMDI (polymethylene polyphenyl isocyanate)

[0072] Weigh 4110, TEOA, H2O, AK-8805, C5H 12 , 8154, stir and mix evenly, then add PMDI to it. After mixing evenly, pour it into a mold. Add the aerogel particles prepared in step 1) to the mold according to the mass ratio of 1:1 with the rigid polyurethane foam foaming liquid. Wait for the polyurethane to foam and complete, that is, after molding and foaming, the composite material is obtained.

[0073] The density of this product is 103 mg / cm 3 , the limiting oxygen index is 30%, the peak heat release is 192 kW / m 2 , the compression modulus is 16 MPa, the thermal conductivity is 21.6 mW / (m·K), and the pore size is 0.2 μm - 12 μm.

[0074] Example 4

[0075] Select the substrate as rigid polyurethane foam:

[0076] 1) Preparation of aerogel colloids: First, dissolve 5.0 g of gellan gum in 92.0 g of deionized water, place it in a 70 °C water bath until the gellan gum is completely dissolved, then place it on a rotary stirrer. Weigh 2.0 g of hydroxymethylated phenol and add it to the above system. After quickly mixing, add 1.0 g of sodium phytate (the solid content of the precursor solution is 8%), mix well, and use a disposable syringe to drop it into a container filled with liquid nitrogen. Collect the obtained hydrogel colloids, place them in a freeze dryer and freeze-dry for three days. Take out the obtained porous aerogel colloids, place them in a vacuum oven at 80 °C for 24 h (to remove the un-freeze-dried bound water), and obtain ternary integrated self-expanding aerogel colloids;

[0077] 2) Preparation of composite materials: The formula of rigid polyurethane foam is

[0078]

[0079] Weigh 4110, TEOA, H2O, AK-8805, C5H 12 、8154, stir and mix well, then add PMDI to it. After mixing well, pour it into a mold. Add the aerogel colloids prepared in step 1) to the mold according to the mass ratio of 1:1 with the rigid polyurethane foam foaming liquid. Wait for the polyurethane to foam and complete, that is, after molding and foaming, the composite material is obtained.

[0080] The density of this product is 90 mg / cm 3 , the limiting oxygen index is 31%, the peak heat release is 187 kW / m 2 , the compression modulus is 16 MPa, the thermal conductivity is 22.4 mW / (m·K), and the pore size is between 0.1 μm - 18 μm.

[0081] Example 5

[0082] Select the substrate as rigid polyurethane foam:

[0083] 1) Preparation of aerogel microspheres: First, add 25.0 g of polyacrylamide (20 wt%) to 32.6 g of deionized water, then weigh 8.0 g of glutaraldehyde (50 wt%) and add it to the above system. After quickly mixing, place it in an 80 °C water bath for 15 minutes, then add 1.0 g of magnesium hydroxide (the solid content of the precursor solution is 15%). After mixing well, transfer it to a heating sprayer and spray it into a container filled with liquid nitrogen. Collect the obtained hydrogel microspheres, place them in a freeze dryer and freeze-dry for three days. Take out the obtained porous aerogel microspheres, place them in a vacuum oven at 80 °C for 24 h (to remove the un-freeze-dried bound water), take them out and sieve twice (100 mesh) to obtain ternary integrated self-expanding aerogel microspheres;

[0084] 2) Preparation of composite materials: The formula of rigid polyurethane foam is

[0085]

[0086]

[0087] Add the 20 php (8.14 wt%) aerogel microspheres prepared in step 1) to the mixture of 4110, TEOA, H2O, AK-8805, C5H 12 , 8154, stir and mix well, then add PMDI thereto, mix well, pour it into a mold and wait for foaming to complete, and place it in an oven at 70 °C for thermosetting molding to obtain the composite material.

[0088] The density of this product is 87 mg / cm 3 , the limiting oxygen index is 26%, the peak heat release is 262 kW / m 2 , the compression modulus is 13 MPa, the thermal conductivity is 22.7 mW / (m·K), and the pore size is 0.8 μm - 48 μm.

[0089] Example 6

[0090] Select the substrate as polystyrene (EPS) foam:

[0091] 1) Preparation of aerogel microspheres: First, dissolve 5.0 g of carboxymethyl cellulose in 75.6 g of deionized water, place it in a 30 °C water bath to completely dissolve the carboxymethyl cellulose, then place it on a rotary stirrer, weigh 10.0 g of glutaraldehyde (50 wt%) and add it to the above system, and then weigh 1.0 g of aluminum hydroxide and add it to the above system (the solid content of the precursor is 12%). After quickly mixing well, transfer it to an electric sprayer and spray it into a container filled with liquid nitrogen, collect the obtained hydrogel microspheres, place them in a freeze dryer and freeze-dry for three days, take out the freeze-dried porous aerogel microspheres, and place them in a vacuum oven at 80 °C for 24 h (to remove the un-freeze-dried bound water) to obtain ternary integrated self-expanding aerogel microspheres;

[0092] 2) Preparation of the composite material: Spread the polystyrene (EPS) beads flat on a tray, then place them in a forced-air drying oven at 100 °C for pre-foaming for 2 minutes, and then place them in a forced-air drying oven at 30 °C for curing for 24 hours to obtain pre-foamed EPS beads. Add 40% of the aerogel microspheres prepared in step 1) to the pre-foamed EPS beads and mix them. After mechanically stirring and mixing well, spread them flat in a mold cavity, close the mold, transfer the mold to a flat vulcanizing machine, heat and foam at 100 °C for 20 minutes, and then cool to room temperature and open the mold to obtain the product, that is, the composite material is obtained after hot pressing molding.

[0093] The density of this material is 54 mg / cm 3 , the limiting oxygen index is 23%, the peak heat release is 382 kW / m 2, the compression modulus is 4 MPa, the thermal conductivity is 27.9 mW / (m·K), and the aerogel pore size is between 7 nm and 90 nm.

[0094] Example 7

[0095] Select the substrate as polystyrene foam:

[0096] 1) Preparation of aerogel particles: First, dissolve 5.0 g of polydopamine in 58.3 g of deionized water, place it in a 30°C water bath to completely dissolve the polydopamine, then place it on a rotary stirrer. Weigh 8.0 g of divalent copper salt (basic copper carbonate, CuCO3·Cu(OH)2, 50 wt%) and add it to the above system. After quickly mixing, add 2.0 g of melamine cyanurate (the solid content of the precursor solution is 15%). After mixing, use a disposable syringe to drop it into a container filled with liquid nitrogen, collect the obtained hydrogel particles, place them in a freeze dryer and freeze-dry for three days. Take out the freeze-dried porous aerogel particles, place them in a vacuum oven at 80°C for 24 h (to remove the un-freeze-dried bound water) to obtain ternary integrated self-expanding aerogel particles;

[0097] 2) Preparation of the composite material: Spread the polystyrene (EPS) beads on a tray, then place them in a 100°C forced-air drying oven to heat and pre-foam for 2 minutes, and then place them in a 30°C forced-air drying oven to cure for 24 hours to obtain pre-foamed EPS beads. Mix the aerogel particles prepared in step 1) with the pre-foamed EPS beads according to a mass ratio of 6:1. After mechanically stirring and mixing evenly, spread them in a mold cavity, close the mold, transfer the mold to a flat vulcanizing machine, heat and foam at 100°C for 20 minutes, and then cool to room temperature and open the mold to obtain the product, that is, the composite material after hot pressing and forming.

[0098] The density of this material is 62 mg / cm 3 , the limiting oxygen index is 25%, the peak heat release is 389 kW / m 2 , the compression modulus is 7 MPa, the thermal conductivity is 25.3 mW / (m·K), and the aerogel pore size is between 0.9 μm and 20.7 μm.

[0099] Example 8

[0100] Select the substrate as polystyrene foam:

[0101] 1) Preparation of aerogel colloids: First, dissolve 5.0 g of hydroxymethyl chitosan in 54.0 g of deionized water. Place it in a 30°C water bath until the hydroxymethyl chitosan is completely dissolved, then place it on a rotary stirrer. Weigh 1.0 g of ammonium polyphosphate and add it to the above system (the solid content of the precursor solution is 10%). After quickly mixing, use a disposable syringe to drop it into a container filled with liquid nitrogen. Collect the obtained hydrogel colloids, place them in a freeze dryer and freeze-dry for three days. Take out the freeze-dried porous aerogel colloids and place them in a vacuum oven at 80°C for 24 h (to remove the un-freeze-dried bound water) to obtain ternary integrated self-expanding aerogel colloids;

[0102] 2) Preparation of composite materials: Spread polystyrene (EPS) beads on a tray, then place them in a 100°C forced-air drying oven and heat them for pre-foaming for 2 minutes, and then place them in a 30°C forced-air drying oven for curing for 24 hours to obtain pre-foamed EPS beads. Mix the aerogel colloids prepared in step 1) with the pre-foamed EPS beads according to a mass ratio of 6:1. After mechanically stirring and mixing evenly, spread them in a mold cavity, close the mold, transfer the mold to a flat vulcanizing machine, heat and foam at 100°C for 20 minutes, and then open the mold after cooling to room temperature to obtain the product, that is, the composite material after hot pressing and forming.

[0103] The density of this material is 64 mg / cm 3 , the limiting oxygen index is 27%, the peak heat release is 291 kW / m 2 , the compression modulus is 8 MPa, the thermal conductivity is 24.8 mW / (m·K), and the pore size of the aerogel is between 0.2 μm and 18 μm.

[0104] Example 9

[0105] Select the substrate as polystyrene foam:

[0106] 1) Preparation of aerogel microspheres: First, dissolve 4.0 g of polyvinyl alcohol in 51.3 g of deionized water. Place it in a 90°C water bath until the polyvinyl alcohol is completely dissolved, then place it on a rotary stirrer. Weigh 2.0 g of formaldehyde and add it to the above system. After quickly mixing, add 1.0 g of phenylphosphonic acid to it (the solid content of the precursor solution is 12%). After mixing evenly, use an ultrasonic sprayer to spray it into a container filled with liquid nitrogen. Collect the obtained hydrogel microspheres, place them in a freeze dryer and freeze-dry for three days. Take out the freeze-dried porous aerogel microspheres and place them in a vacuum oven at 80°C for 24 h (to remove the un-freeze-dried bound water) to obtain ternary integrated self-expanding aerogel microspheres;

[0107] 2) Preparation of composite material: Spread polystyrene (EPS) beads flat on a tray, then place them in a forced-air drying oven at 100 °C for pre-foaming for 2 minutes, and then place them in a forced-air drying oven at 30 °C for curing for 24 hours to obtain pre-foamed EPS beads. Add 40% of the aerogel microspheres prepared in step 1) to the pre-foamed EPS beads and mix them. After mechanical stirring and mixing evenly, spread them flat in the mold cavity, close the mold, transfer the mold to a flat vulcanizing machine, heat and foam at 100 °C for 20 minutes, and then open the mold after cooling to room temperature to obtain the product, that is, the composite material after hot pressing and forming.

[0108] The density of this material is 48 mg / cm 3 , the limiting oxygen index is 23.5%, the peak heat release is 398 kW / m 2 , the compression modulus is 5 MPa, the thermal conductivity is 28.8 mW / (m·K), and the pore size of the aerogel is 22 nm - 110 nm.

[0109] Example 10

[0110] Select the base material as polystyrene foam:

[0111] 1) Pretreatment: Weigh 35.0 g of melamine, add 67.6 g of formaldehyde solution to it, and then add 197.4 g of deionized water. Place it in a water bath at 85 °C and react for 1.5 h. During the reaction, detect the change of the solution pH value, and use NaOH to control the solution pH to 9 - 10. After the reaction, obtain the hydroxymethylated melamine solution (MOH, 20 wt%). Put it in the refrigerator and freeze for two days, then put it in a freeze dryer and freeze-dry for three days, and take it out and pack it in a plastic-sealed bag.

[0112] 2) Preparation of aerogel colloids: First, dissolve 5.0 g of gelatin (PG) in 89.0 g of deionized water. Place it in a water bath at 70 °C to completely dissolve the gelatin (PG), and then place it on a rotary stirrer. Weigh 4.0 g of hydroxymethylated melamine and add it to the above system. After quickly mixing evenly, add 2.0 g of aminotrimethylene phosphonic acid (ATMP, 50 wt%) (the solid content of the precursor solution is 10%) to it. After mixing evenly, use a disposable syringe to drop it into a container filled with liquid nitrogen, collect the obtained hydrogel colloids, place them in a freeze dryer and freeze-dry for three days, take out the freeze-dried porous aerogel colloids, and place them in a vacuum oven at 80 °C for 24 h (to remove the un-freeze-dried bound water) to obtain ternary integrated self-expanding aerogel colloids;

[0113] 3) Preparation of composite material: Spread polystyrene (EPS) beads flat on a tray, then place them in a forced-air drying oven at 100 °C for pre-foaming for 2 minutes, and then place them in a forced-air drying oven at 30 °C for curing for 24 hours to obtain pre-foamed EPS beads. Mix the porous rubber particles prepared in step 1) with the pre-foamed EPS beads according to a mass ratio of 6:1. After mechanical stirring and mixing evenly, spread them flat in a mold cavity, close the mold, transfer the mold to a flat vulcanizing machine, heat and foam at 100 °C for 20 minutes, and then open the mold after cooling to room temperature to obtain the product, that is, the composite material after hot pressing and forming.

[0114] The density of this material is 71 mg / cm 3 , the limiting oxygen index is 27.5%, the peak heat release is 323 kW / m 2 , the compression modulus is 7 MPa, the thermal conductivity is 22.9 mW / (m·K), and the pore size of the aerogel is between 5.8 μm and 89 μm.

[0115] Example 11

[0116] Select the base material as foamed polypropylene:

[0117] 1) Pretreatment: Weigh 35.0 g of melamine, add 67.6 g of formaldehyde solution to it, and then add 197.4 g of deionized water. Place it in a water bath at 85 °C and react for 1.5 h. During the reaction process, detect the change of the solution pH value, and use NaOH to control the solution pH to 9-10. After the reaction, obtain hydroxymethylated melamine solution (MOH, 20 wt%). Put it in the refrigerator and freeze for two days, then put it in a freeze dryer and freeze-dry for three days, and take it out and pack it in a plastic-sealed bag.

[0118] 2) Preparation of aerogel microspheres: First, dissolve 2.0 g of soy protein isolate in 21.8 g of deionized water, place it in a water bath at 80 °C to completely dissolve the soy protein isolate, and then place it on a rotary stirrer. Weigh 2.0 g of MOH and add it to the above system. After quickly mixing evenly, add 2.0 g of aminotrimethylene phosphonic acid (ATMP, 50 wt%) (the solid content of the precursor solution is 18%) to it. After mixing evenly, use a heating spray gun to spray it into a container filled with liquid nitrogen, collect the obtained hydrogel microspheres, place them in a freeze dryer and freeze-dry for three days, take out the obtained porous aerogel microspheres, place them in a vacuum oven at 80 °C for 24 h (to remove the un-freeze-dried bound water), take it out and sieve it twice (100 mesh) to obtain ternary integrated self-expanding aerogel microspheres;

[0119] 3) Preparation of composite material: First, place the polypropylene resin in a forced-air drying oven at 80 °C for drying for 12 hours, then add 5 wt% of microspheres, mix evenly, melt and extrude through a twin-screw extruder, and inject mold with an injection molding machine. Open the mold to obtain the product, that is, the composite material after injection molding.

[0120] The density of this material is 69 mg / cm 3 , the limiting oxygen index is 25%, and the peak heat release is 197 kW / m 2 , the tensile strength is 17 MPa, the thermal conductivity is 133 mW / (m·K), and the aerogel pore size is between 38 nm and 120 nm.

[0121] Example 12

[0122] Select the base material as foamed polypropylene:

[0123] 1) Preparation of aerogel microspheres: First, dissolve 5.0 g of gelatin (FG) in 62.75 g of deionized water, place it in a 70°C water bath to completely dissolve the gelatin (FG), then place it on a rotary stirrer. Weigh 1.0 g of phytic acid (PA, 50 wt%) and add it to the above system (the solid content of the precursor solution is 8%). After quickly mixing, use a manual spray bottle to spray it into a container filled with liquid nitrogen, collect the obtained hydrogel microspheres, place them in a freeze dryer and freeze-dry for three days. Take out the freeze-dried porous aerogel microspheres, place them in a vacuum oven at 80°C for 24 h (to remove the un-freeze-dried bound water), take out and sieve twice (100 mesh) to obtain ternary integrated self-expanding aerogel microspheres;

[0124] 2) Preparation of the composite material: First, place the polypropylene resin in a forced-air oven and dry it at 80°C for 12 hours. Then add 5 wt% of microspheres, mix well, melt-extrude through a twin-screw extruder, and perform injection molding with an injection molding machine. Open the mold to obtain the product, that is, the composite material is obtained after injection molding.

[0125] The density of this material is 72 mg / cm 3 , the limiting oxygen index is 25.5%, and the peak heat release is 176 kW / m 2 , the tensile strength is 16 MPa, the thermal conductivity is 131 mW / (m·K), and the aerogel pore size is between 33 nm and 100 nm.

[0126] Example 13

[0127] Select the base material as foamed polypropylene:

[0128] 1) Preparation of aerogel microspheres: First, dissolve 5.0 g of phenolic resin in 54.0 g of deionized water, place it in a 30°C water bath to completely dissolve the phenolic resin, then place it on a rotary stirrer. Weigh 1.0 g of ammonium polyphosphate and add it to the above system (the solid content of the precursor solution is 10%). After quickly mixing, use a manual spray bottle to spray it into a container filled with liquid nitrogen, collect the obtained hydrogel microspheres, place them in a freeze dryer and freeze-dry for three days. Take out the freeze-dried porous aerogel microspheres, place them in a vacuum oven at 80°C for 24 h (to remove the un-freeze-dried bound water), take out and sieve twice (100 mesh) to obtain ternary integrated self-expanding aerogel microspheres;

[0129] 2) Preparation of the composite material: First, put the polypropylene resin into a forced-air oven and dry it at 80 °C for 12 hours. Then, add 5 wt% microspheres. After mixing evenly, melt and extrude through a twin-screw extruder, and then perform injection molding with an injection molding machine. Open the mold to obtain the product, that is, the composite material is obtained after injection molding.

[0130] The density of this material is 71 mg / cm 3 , the limiting oxygen index is 25%, and the peak heat release is 158 kW / m 2 , the tensile strength is 17 MPa, the thermal conductivity is 126 mW / (m·K), and the aerogel pore size is between 14 nm and 80 nm.

[0131] Example 14

[0132] Select the base material as foamed polypropylene:

[0133] 1) Preparation of aerogel microspheres: First, dissolve 4.0 g of melamine formaldehyde resin in 42.0 g of deionized water. Place it in a water bath at 200 °C to completely dissolve the melamine formaldehyde resin, and then place it on a rotary stirrer. Weigh 2.0 g of divalent copper salt (basic copper carbonate, CuCO3·Cu(OH)2, 50 wt%) and add it to the above system. After quickly mixing evenly, add 2.0 g of phytic acid (PA, 50 wt%) (the solid content of the precursor solution is 12%). After mixing evenly, use a heating sprayer to spray it into a container filled with liquid nitrogen, collect the obtained hydrogel microspheres, place them in a freeze dryer and freeze-dry for three days. Take out the freeze-dried porous aerogel microspheres, place them in a vacuum oven at 80 °C for 24 h (to remove the un-freeze-dried bound water), take out and sieve twice (100 mesh) to obtain ternary integrated self-expanding aerogel microspheres;

[0134] 2) Preparation of the composite material: First, put the polypropylene resin into a forced-air oven and dry it at 80 °C for 12 hours. Then, add 5 wt% microspheres. After mixing evenly, melt and extrude through a twin-screw extruder, and then perform injection molding with an injection molding machine. Open the mold to obtain the product, that is, the composite material is obtained after injection molding.

[0135] The density of this material is 84 mg / cm 3 , the limiting oxygen index is 24.5%, and the peak heat release is 146 kW / m 2 , the tensile strength is 18 MPa, the thermal conductivity is 139 mW / (m·K), and the aerogel pore size is between 42 nm and 120 nm.

[0136] Example 15

[0137] Select the base material as foamed polypropylene:

[0138] 1) Preparation of aerogel microspheres: First, dissolve 5.0 g of gelatin (FG) in 62.75 g of deionized water. Place it in a 70 °C water bath until the gelatin (FG) is completely dissolved, then place it on a rotary stirrer. Weigh 1.0 g of phytic acid (PA, 50 wt%) and add it to the above system (the solid content of the precursor solution is 8%). After quickly mixing, use a heating sprayer to spray it into a container filled with liquid nitrogen. Collect the obtained hydrogel microspheres, place them in a freeze dryer and freeze-dry for three days. Take out the freeze-dried porous aerogel microspheres, place them in a vacuum oven at 80 °C for 24 h (to remove the un-freeze-dried bound water), take out and sieve twice (100 mesh) to obtain ternary integrated self-expanding aerogel microspheres;

[0139] 2) Preparation of composite materials: First, place the polypropylene resin in a forced-air oven and dry it at 80 °C for 12 hours. Then add 5 wt% microspheres, mix well, melt-extrude through a twin-screw extruder, and inject mold using an injection molding machine. Open the mold to obtain the product, that is, the composite material after injection molding.

[0140] The density of this material is 86 mg / cm 3 , the limiting oxygen index is 27%, the peak heat release is 152 kW / m 2 , the tensile strength is 17 MPa, the thermal conductivity is 136 mW / (m·K), and the pore size of the aerogel is between 38 nm and 112 nm.

[0141] Example 16

[0142] Select the substrate as polyimide foam:

[0143] 1) Pretreatment: Weigh 35.0 g of melamine, add 67.6 g of formaldehyde solution to it, and then add 197.4 g of deionized water. Place it in an 85 °C water bath and react for 1.5 h. During the reaction process, detect the change in the pH value of the solution, and control the pH of the solution at 9 - 10 with NaOH. After the reaction, obtain the hydroxymethylated melamine solution (MOH, 20 wt%). Put it in the refrigerator and freeze for two days, then put it in a freeze dryer and freeze-dry for three days. Take out and pack it in a plastic-sealed bag.

[0144] 2) Preparation of aerogel microspheres: First, dissolve 5.0 g of starch in 51.0 g of deionized water. Place it in a 70 °C water bath until the starch is completely dissolved, then place it on a rotary stirrer. Weigh 3.0 g of MOH and add it to the above system. After quickly mixing, add 1.0 g of magnesium hydroxide (the solid content of the precursor solution is 15%). After mixing, use a heating sprayer to spray it into a container filled with liquid nitrogen. Collect the obtained hydrogel microspheres, place them in a freeze dryer and freeze-dry for three days. Take out the freeze-dried porous aerogel microspheres, place them in a vacuum oven at 80 °C for 24 h (to remove the un-freeze-dried bound water), take out and sieve twice (100 mesh) to obtain ternary integrated self-expanding aerogel microspheres;

[0145] 3) Preparation of composite material: ① Compound catalyst: Add 10 g of pyridine, 1.5 g of triethanolamine, 21.5 g of dimethyl silicone oil, 100 g of deionized water, and 25 g of diethylene glycol into a 250 mL conical flask, mix and stir magnetically for half an hour until evenly dispersed for later use. ② White material: Weigh 2 g of N,N-dimethylformamide (DMF) and 1.09 g of pyromellitic dianhydride (PMDA) at room temperature in a dry 50 mL beaker, place it in a 65 °C water bath, seal the beaker mouth with plastic wrap, stir magnetically until PMDA is completely dissolved, add 2 g of ethanol to it, continue to stir for 30 minutes until the reaction is complete, cool to room temperature and then add 1.2 g of compound catalyst, stir evenly to obtain a colorless and transparent solution, that is, the foaming white material. ③ Black material: Add 3 g of DMF and 6 g of PMDI to a dry plastic cup and stir evenly. At this time, the solution is yellow-brown. Then add 1.55 g of 3,3′,4,4′-diphenylether tetracarboxylic dianhydride (ODPA) to it, and always keep the same molar ratio of dianhydride and PMDI in the white material and the black material. Continue to stir until ODPA is completely dissolved. At this time, the solution is light yellow, and the preparation of the black material is completed. ④ Preparation of composite material: After adding 8 wt% microspheres to the foaming white material and mixing evenly, quickly pour the black material into it to complete the foaming process. After curing and heating at 80 °C for 2 hours, 120 °C for 2 hours, 150 °C for 90 minutes, 180 °C for 90 minutes, 210 °C for 60 minutes, and 230 °C for 60 minutes, the composite material is obtained after thermosetting molding.

[0146] The density of this material is 67 mg / cm 3 , the limiting oxygen index is 25%, the peak heat release is 185 kW / m 2 , the compression modulus is 2.4 MPa, the thermal conductivity is 30.8 mW / (m·K), and the aerogel pore size is between 28 nm and 110 nm.

[0147] Example 17

[0148] Select the substrate as polyimide foam:

[0149] 1) Preparation of aerogel microspheres: First, dissolve 4.0 g of lignin in 50.3 g of deionized water, place it in a 120 °C water bath to completely soften the lignin, then place it on a rotary stirrer, and weigh 2.0 g of divalent copper salt (basic copper carbonate, CuCO3·Cu(OH)2, 50 wt%) and add it to the above system. After quickly mixing evenly, add 2.0 g of sodium phytate (the solid content of the precursor solution is 12%). After mixing evenly, use an electrospinning instrument to spray it into a container filled with liquid nitrogen, collect the obtained hydrogel microspheres, place them in a freeze dryer and freeze-dry for three days, take out the freeze-dried porous aerogel microspheres, place them in a vacuum oven at 80 °C for 24 h (to remove the un-freeze-dried bound water), take out and sieve twice (100 mesh) to obtain ternary integrated self-expanding aerogel microspheres;

[0150] 2) Preparation of composite material: ① Compound catalyst: Add 10 g of pyridine, 1.5 g of triethanolamine, 21.5 g of dimethyl silicone oil, 100 g of deionized water, and 25 g of diethylene glycol into a 250 mL conical flask, mix and stir magnetically for half an hour until evenly dispersed for later use. ② White material: Weigh 2 g of N,N-dimethylformamide (DMF) and 1.09 g of pyromellitic dianhydride (PMDA) at room temperature in a dry 50 mL beaker, place it in a 65 °C water bath, seal the beaker mouth with plastic wrap, stir magnetically until PMDA is completely dissolved, add 2 g of ethanol to it, continue to stir for 30 minutes until the reaction is complete, cool to room temperature and then add 1.2 g of compound catalyst, stir evenly to obtain a colorless transparent solution, namely the foaming white material. ③ Black material: Add 3 g of DMF and 6 g of PMDI to a dry plastic cup and stir evenly. At this time, the solution is yellowish brown. Then add 1.55 g of 3,3′,4,4′-diphenyl ether tetracarboxylic dianhydride (ODPA) to it, always keep the same molar ratio of dianhydride and PMDI in the white material and the black material, continue to stir until ODPA is completely dissolved. At this time, the solution is light yellow, and the preparation of the black material is completed. ④ Preparation of composite material: After adding 8 wt% microspheres to the foaming white material and mixing evenly, quickly pour the black material into it to complete the foaming process. After curing and heating at 80 °C for 2 hours, 120 °C for 2 hours, 150 °C for 90 minutes, 180 °C for 90 minutes, 210 °C for 60 minutes, and 230 °C for 60 minutes, the composite material is obtained after thermosetting molding.

[0151] The density of this material is 73 mg / cm 3 , the limiting oxygen index is 24.5%, the peak heat release is 158 kW / m 2 , the compression modulus is 1.8 MPa, the thermal conductivity is 27.7 mW / (m·K), and the aerogel pore size is between 18 nm and 106 nm.

[0152] Example 18

[0153] Select the substrate as polyimide foam:

[0154] 1) Preparation of aerogel particles: First, dissolve 5.0 g of guar gum in 53.0 g of deionized water, place it in a 120 °C water bath until the guar gum is completely dissolved, then place it on a rotary stirrer. Weigh 2.0 g of phytic acid (PA, 50 wt%) and add it to the above system (the solid content of the precursor solution is 10%). After quickly mixing evenly, use a disposable syringe to drop it into a container filled with liquid nitrogen, collect the obtained hydrogel particles, place them in a freeze dryer and freeze-dry for three days. Take out the freeze-dried porous aerogel particles and place them in a vacuum oven at 80 °C for 24 h (to remove the un-freeze-dried bound water) to obtain ternary integrated self-expanding aerogel particles;

[0155] 2) Preparation of composite material: ① Compound catalyst: Add 10 g of pyridine, 1.5 g of triethanolamine, 21.5 g of dimethyl silicone oil, 100 g of deionized water, and 25 g of diethylene glycol into a 250 mL conical flask, mix and stir magnetically for half an hour until evenly dispersed for later use. ② White material: Weigh 2 g of N,N-dimethylformamide (DMF) and 1.09 g of pyromellitic dianhydride (PMDA) at room temperature in a dry 50 mL beaker, place it in a 65 °C water bath, seal the beaker mouth with plastic wrap, stir magnetically until PMDA is completely dissolved, add 2 g of ethanol to it, continue stirring for 30 minutes until the reaction is complete, cool to room temperature and then add 1.2 g of compound catalyst, stir evenly to obtain a colorless transparent solution as the foaming white material. ③ Black material: Add 3 g of DMF and 6 g of PMDI to a dry plastic cup and stir evenly. At this time, the solution is yellowish-brown. Then add 1.55 g of 3,3′,4,4′-diphenylether tetracarboxylic dianhydride (ODPA) to it, always keep the same molar ratio of dianhydride and PMDI in the white material and the black material, continue stirring until ODPA is completely dissolved. At this time, the solution is light yellow, and the preparation of the black material is completed. ④ Preparation of composite material: After mixing the foaming white material evenly, pour the black material into it, quickly mix evenly, then pour it into a mold, quickly pour the rubber particles with a mass ratio of 1﹕1 to the foaming liquid into the mold. After waiting for the foaming process to be completed, carry out curing and heating at 80 °C for 2 hours, 120 °C for 2 hours, 150 °C for 90 minutes, 180 °C for 90 minutes, 210 °C for 60 minutes, and 230 °C for 60 minutes, that is, the composite material is obtained after thermosetting molding.

[0156] The density of this material is 84 mg / cm 3 , the limiting oxygen index is 27%, and the peak heat release is 121 kW / m 2 , the compression modulus is 7 MPa, the thermal conductivity is 28.4 mW / (m·K), and the pore diameter of the aerogel is 8.6 μm - 92 μm.

[0157] Example 19

[0158] Select the substrate as polyimide foam:

[0159] 1) Pretreatment: Weigh 35.0 g of melamine, add 67.6 g of formaldehyde solution to it, then add 197.4 g of deionized water, place it in an 85 °C water bath and react for 1.5 h. During the reaction process, detect the change of the solution pH value, control the solution pH with NaOH to be 9 - 10. After the reaction is completed, obtain the hydroxymethylated melamine solution (MOH, 20 wt%), put it in the refrigerator and freeze for two days, then put it in a freeze dryer and freeze-dry for three days, and take it out and pack it in a plastic-sealed bag.

[0160] 2) Preparation of aerogel particles: First, dissolve 5.0 g of gelatin (PG) in 92.0 g of deionized water. Place it in a 70 °C water bath until the gelatin is completely dissolved, then place it on a rotary stirrer. Weigh 2.0 g of MOH and add it to the above system. After quickly mixing, add 1.0 g of phosphite (the solid content of the precursor solution is 8%) to it. After mixing evenly, use a disposable syringe to drop it into a container filled with liquid nitrogen, collect the obtained hydrogel particles, place them in a freeze dryer and freeze-dry for three days. Take out the freeze-dried porous aerogel particles and place them in a vacuum oven at 80 °C for 24 h (to remove the un-freeze-dried bound water) to obtain ternary integrated self-expanding aerogel particles;

[0161] 3) Preparation of composite materials: ① Compound catalyst: Add 10 g of pyridine, 1.5 g of triethanolamine, 21.5 g of dimethyl silicone oil, 100 g of deionized water, and 25 g of diethylene glycol to a 250 mL conical flask, and mix and stir magnetically for half an hour until evenly dispersed for later use. ② White material: Weigh 2 g of N,N-dimethylformamide (DMF) and 1.09 g of pyromellitic dianhydride (PMDA) at room temperature in a dry 50 mL beaker, place it in a 65 °C water bath, seal the beaker mouth with plastic wrap, and stir magnetically until PMDA is completely dissolved. Add 2 g of ethanol to it, continue to stir for 30 minutes until the reaction is complete, cool to room temperature, and then add 1.2 g of the compound catalyst and stir evenly to obtain a colorless and transparent solution, that is, the foaming white material. ③ Black material: Add 3 g of DMF and 6 g of PMDI to a dry plastic cup and stir evenly. At this time, the solution is yellowish-brown. Then add 1.55 g of 3,3′,4,4′-diphenylether tetracarboxylic dianhydride (ODPA) to it, and always keep the same molar ratio of dianhydride and PMDI in the white material and the black material. Continue to stir until ODPA is completely dissolved. At this time, the solution is light yellow, and the preparation of the black material is completed. ④ Preparation of composite materials: After mixing the foaming white material evenly, pour the black material into it, quickly mix it evenly, then pour it into a mold, quickly pour the particles with a mass ratio of 1:1 to the foaming liquid into the mold. After waiting for the foaming process to be completed, carry out curing and heating at 80 °C for 2 hours, 120 °C for 2 hours, 150 °C for 90 minutes, 180 °C for 90 minutes, 210 °C for 60 minutes, and 230 °C for 60 minutes, that is, after thermosetting and forming, the composite material is obtained.

[0162] The density of this material is 86 mg / cm 3 , the limiting oxygen index is 28%, the peak heat release is 109 kW / m 2 , the compression modulus is 9 MPa, the thermal conductivity is 29.4 mW / (m·K), and the aerogel pore size is between 7.9 μm - 112 μm.

[0163] Example 20

[0164] Select the substrate as polyimide foam:

[0165] 1) Pretreatment: Weigh 35.0 g of melamine, add 67.6 g of formaldehyde solution to it, then add 197.4 g of deionized water. Place it in a water bath at 85 °C and react for 1.5 h. During the reaction, monitor the change in the pH value of the solution, and control the pH of the solution at 9 - 10 with NaOH. After the reaction, obtain a hydroxymethylated melamine solution (MOH, 20 wt%). Put it in the refrigerator and freeze for two days, then place it in a freeze dryer and freeze-dry for three days. Take it out and put it in a plastic-sealed bag.

[0166] 2) Preparation of aerogel microspheres: First, dissolve 5.0 g of chitosan in 103.5 g of deionized water. Place it in a water bath at 120 °C until the chitosan is completely dissolved, then place it on a rotary stirrer. Weigh 3.0 g of MOH and add it to the above system. After quickly mixing evenly, add 1.0 g of aluminum hypophosphite (the solid content of the precursor solution is 8%) to it. After mixing evenly, use a pneumatic sprayer to spray it into a container filled with liquid nitrogen, collect the obtained hydrogel microspheres, place them in a freeze dryer and freeze-dry for three days. Take out the obtained porous aerogel microspheres, place them in a vacuum oven at 80 °C for 24 h (to remove the un-freeze-dried bound water), take them out and sieve them twice (100 mesh) to obtain ternary integrated self-expanding aerogel microspheres;

[0167] 3) Preparation of composite materials: ① Compound catalyst: Add 10 g of pyridine, 1.5 g of triethanolamine, 21.5 g of dimethyl silicone oil, 100 g of deionized water, and 25 g of diethylene glycol to a 250 mL conical flask, and mix and stir magnetically for half an hour until evenly dispersed for later use. ② White material: Weigh 2 g of N,N-dimethylformamide (DMF) and 1.09 g of pyromellitic dianhydride (PMDA) at room temperature in a dry 50 mL beaker, place it in a water bath at 65 °C, seal the beaker mouth with plastic wrap, and stir magnetically until PMDA is completely dissolved. Add 2 g of ethanol to it, continue to stir for 30 minutes until the reaction is complete, cool to room temperature, and then add 1.2 g of the compound catalyst and stir evenly to obtain a colorless and transparent solution as the foaming white material. ③ Black material: Add 3 g of DMF and 6 g of PMDI to a dry plastic cup and stir evenly. At this time, the solution is yellow-brown. Then add 1.55 g of 3,3′,4,4′-diphenylether tetracarboxylic dianhydride (ODPA) to it, and always keep the same molar ratio of dianhydride and PMDI in the white material and the black material. Continue to stir until ODPA is completely dissolved. At this time, the solution is light yellow, and the preparation of the black material is completed. ④ Preparation of composite materials: Add 8 wt% of microspheres to the foaming white material and mix evenly, then quickly pour the black material into it to complete the foaming process. After curing and heating at 80 °C for 2 hours, 120 °C for 2 hours, 150 °C for 90 minutes, 180 °C for 90 minutes, 210 °C for 60 minutes, and 230 °C for 60 minutes, a composite material is obtained after thermosetting and molding.

[0168] The density of this material is 64 mg / cm 3, the limiting oxygen index is 26%, and the peak heat release is 168 kW / m 2 , the compression modulus is 2.7 MPa, the thermal conductivity is 27.1 mW / (m·K), and the aerogel pore size is between 16 nm and 170 nm.

[0169] Comparative Example 1

[0170] Compared with Examples 1, 2, 3, 4, and 5 in terms of reaction raw materials and process, the only difference is that no aerogel microspheres / colloidal particles are added, and only rigid polyurethane foam is used. The formula is as follows:

[0171]

[0172] Weigh 4110, H2O, A 33 B, T 12 , AK-8805, C5H 12 , after stirring and mixing evenly, add PMDI to it. After mixing evenly, pour it into a mold and wait for the polyurethane to foam. After the foaming is completed, the molded foam will obtain the material.

[0173] The density of this material is 102 mg / cm 3 , the limiting oxygen index is 18%, and the peak heat release is 311 kW / m 2 , the compression modulus is 16 MPa, and the thermal conductivity is 38.6 mW / (m·K).

[0174] Comparative Example 2

[0175] Compared with Examples 1, 2, 3, 4, and 5 in terms of reaction raw materials and process, the only difference is that only gelatin (FG) is used to prepare aerogel microspheres by pneumatic spraying to prepare a composite material with rigid polyurethane foam.

[0176] 1) Preparation of aerogel microspheres: First, dissolve 5.0 g of gelatin (FG) in 22.8 g of deionized water. After placing it in a 70°C water bath to completely dissolve the gelatin (FG), use a pneumatic sprayer to spray it into a container filled with liquid nitrogen. Collect the prepared hydrogel microspheres, place them in a freeze dryer and freeze-dry for three days. Take out the freeze-dried porous aerogel microspheres, place them in a vacuum oven at 80°C for 24 h (to remove the un-freeze-dried bound water), take them out and sieve them twice (100 mesh) to obtain ternary integrated self-expanding aerogel microspheres;

[0177] 2) Preparation of the composite material: The formula of the rigid polyurethane foam is

[0178]

[0179] Add the 15php (6.29 wt%) aerogel microspheres prepared in step 1) to the mixture of 4110, TEOA, H2O, AK-8805, C5H 12 , 8154. After stirring and mixing evenly, add PMDI to it. After mixing evenly, pour it into a mold and wait for foaming to complete, then place it in an oven at 70 °C for thermosetting molding to obtain the composite material.

[0180] The density of this material is 98 mg / cm 3 , the limiting oxygen index is 19.5%, the peak heat release is 306 kW / m 2 , the compression modulus is 16 MPa, the thermal conductivity is 37.4 mW / (m·K), and the aerogel pore size is between 80 nm and 200 nm.

[0181] Comparative Example 3

[0182] Compared with Examples 1, 2, 3, 4, and 5 in terms of reaction raw materials and process, the only difference is that: only gelatin (FG) is used to prepare aerogel particles by the method of dropping with a disposable syringe, and a composite material is prepared with rigid polyurethane foam.

[0183] 1) Preparation of aerogel particles: First, dissolve 5.0 g of gelatin (FG) in 57.5 g of deionized water. After placing it in a 70 °C water bath to completely dissolve the gelatin (FG), use a disposable syringe to drop it into a container filled with liquid nitrogen, collect the obtained hydrogel particles, place them in a freeze dryer for three days of freeze-drying, take out the obtained porous aerogel particles, and place them in a vacuum oven at 80 °C for 24 h (to remove the un-freeze-dried bound water) to obtain ternary integrated self-expanding aerogel particles;

[0184] 2) Preparation of composite material: The formula of rigid polyurethane foam is

[0185]

[0186] Weigh 4110, TEOA, H2O, AK-8805, C5H 12 , 8154, stir and mix evenly, then add PMDI to it. After mixing evenly, pour it into a mold, and add the aerogel particles prepared in step 1) to the mold according to the mass ratio of 1:1 with the rigid polyurethane foam foaming liquid. Wait for the polyurethane to complete foaming, that is, after molding and foaming, the composite material is obtained.

[0187] The density of this material is 104 mg / cm 3 , the limiting oxygen index is 20%, the peak heat release is 298 kW / m 2 , the compression modulus is 18 MPa, the thermal conductivity is 34.5 mW / (m·K), and the aerogel pore size is between 7 μm and 48 μm.

[0188] Comparative Example 4

[0189] The reaction raw materials and process are the same as those in Example 6, Example 7, Example 8, Example 9, and Example 10, and the difference is only that: aerogel microspheres / granules are not added, and only polystyrene foam is used. The preparation is as follows:

[0190] Spread the EPS beads on a tray, then place them in a forced-air drying oven at 100 °C for pre-foaming for 2 minutes, and then place them in a forced-air drying oven at 30 °C for curing for 24 hours to obtain pre-foamed EPS beads. Spread the pre-foamed EPS beads in the mold cavity, close the mold, transfer the mold to a flat vulcanizing machine, heat and foam at 100 °C for 20 minutes, and then open the mold after cooling to room temperature to obtain the product, that is, the material after hot pressing and forming.

[0191] The density of this material is 58 mg / cm 3 , the limiting oxygen index is 18%, and the peak heat release is 398 kW / m 2 , the compression modulus is 1.6 MPa, and the thermal conductivity is 34.8 mW / (m·K).

[0192] Comparative Example 5

[0193] The reaction raw materials and process are the same as those in Example 6, Example 7, Example 8, Example 9, and Example 10, and the difference is only that: only gelatin (FG) is used to prepare aerogel microspheres by a pneumatic spraying method, and a composite material is prepared with polystyrene foam. The preparation is as follows:

[0194] 1) Preparation of aerogel microspheres: First, dissolve 5.0 g of gelatin (FG) in 36.7 g of deionized water, place it in a water bath at 70 °C to completely dissolve the gelatin (FG), then use a pneumatic sprayer to spray it into a container filled with liquid nitrogen, collect the obtained hydrogel microspheres, place them in a freeze dryer for freeze-drying for three days, take out the freeze-dried porous aerogel microspheres, place them in a vacuum oven at 80 °C for 24 h (to remove the un-freeze-dried bound water), take out and sieve twice (100 mesh) to obtain ternary integrated self-expanding aerogel microspheres;

[0195] 2) Preparation of composite material: Spread the EPS beads on a tray, then place them in a forced-air drying oven at 100 °C for pre-foaming for 2 minutes, and then place them in a forced-air drying oven at 30 °C for curing for 24 hours to obtain pre-foamed EPS beads. Add 40% of the aerogel microspheres prepared in step 1) to the EPS pre-foamed beads and mix them, stir evenly with a mechanical stirrer, spread them in the mold cavity, close the mold, transfer the mold to a flat vulcanizing machine, heat and foam at 100 °C for 20 minutes, and then open the mold after cooling to room temperature to obtain the product, that is, the composite material after hot pressing and forming.

[0196] The density of this material is 50 mg / cm 3, the limiting oxygen index is 19%, and the peak heat release is 387 kW / m 2 , the compression modulus is 3.7 MPa, the thermal conductivity is 33.9 mW / (m·K), and the aerogel pore size is between 90 nm and 180 nm.

[0197] Comparative Example 6

[0198] The reaction raw materials and process are the same as those in Examples 6, 7, 8, 9, and 10, and the difference is only that: only gelatin (FG) is used to prepare aerogel particles by the method of dropping with a disposable syringe, and a composite material is prepared with polystyrene foam. The preparation is as follows:

[0199] 1) Preparation of aerogel particles: First, dissolve 5.0 g of gelatin (FG) in 36.7 g of deionized water. After placing it in a 70°C water bath to completely dissolve the gelatin (FG), use a disposable syringe to drop it into a container filled with liquid nitrogen, collect the obtained hydrogel particles, place them in a freeze dryer and freeze-dry for three days, take out the freeze-dried porous aerogel particles, and place them in a vacuum oven at 80°C for 24 h (to remove the un-freeze-dried bound water) to obtain ternary integrated self-expanding aerogel particles;

[0200] 2) Preparation of the composite material: Spread the EPS beads on a tray, then place them in a 100°C forced-air drying oven and heat them for pre-foaming for 2 minutes, and then place them in a 30°C forced-air drying oven for curing for 24 hours to obtain pre-foamed EPS beads. Mix the aerogel particles prepared in step 1) with the pre-foamed EPS beads at a ratio of 6:1, stir them evenly by mechanical stirring, spread them in a mold cavity, close the mold, transfer the mold to a flat vulcanizing machine, heat and foam at 100°C for 20 minutes, and then open the mold after cooling to room temperature to obtain the product, that is, the composite material after hot pressing and forming.

[0201] The density of this material is 60 mg / cm 3 , the limiting oxygen index is 22%, and the peak heat release is 356 kW / m 2 , the compression modulus is 5.4 MPa, the thermal conductivity is 32.6 mW / (m·K), and the aerogel pore size is between 3 μm and 39 μm.

[0202] Comparative Example 7

[0203] The reaction raw materials and process are the same as those in Examples 11, 12, 13, 14, and 15, and the difference is only that: no aerogel microspheres / particles are added, and only foamed polypropylene is used. The preparation is as follows:

[0204] First, place the polypropylene resin in a forced-air drying oven at 80°C and dry it for 12 hours, then melt and extrude it through a twin-screw extruder, and inject it with an injection molding machine, and open the mold to obtain the product, that is, the material after injection molding.

[0205] The density of this material is 85 mg / cm 3 , the limiting oxygen index is 18%, and the peak heat release is 211 kW / m 2 , the tensile strength is 18 MPa, and the thermal conductivity is 202 mW / (m·K).

[0206] Comparative Example 8

[0207] Compared with Examples 11, 12, 13, 14, and 15 in terms of reaction raw materials and process, the only difference is that only gelatin (FG) is used to prepare aerogel microspheres by pneumatic spraying method, and composites are prepared with foamed polypropylene. The preparation is as follows:

[0208] 1) Preparation of aerogel microspheres: First, dissolve 5.0 g of gelatin (FG) in 57.5 g of deionized water. After placing it in a 70°C water bath to completely dissolve the gelatin (FG), spray it into a container filled with liquid nitrogen using a pneumatic sprayer, collect the obtained hydrogel microspheres, place them in a freeze dryer and freeze-dry for three days. Take out the freeze-dried porous aerogel microspheres, place them in a vacuum oven at 80°C for 24 h (to remove the un-freeze-dried bound water), take out and sieve twice (100 mesh) to obtain ternary integrated self-expanding aerogel microspheres;

[0209] 2) Preparation of composites: First, put the polypropylene resin into a forced-air oven and dry it at 80°C for 12 hours. Then add 5 wt% microspheres, mix well, melt-extrude through a twin-screw extruder, and inject mold using an injection molding machine. Open the mold to obtain the product, that is, the composite material is obtained after injection molding.

[0210] The density of this material is 87 mg / cm 3 , the limiting oxygen index is 21%, and the peak heat release is 203 kW / m 2 , the tensile strength is 16 MPa, the thermal conductivity is 194 mW / (m·K), and the pore size of the aerogel is between 72 nm and 180 nm.

[0211] Comparative Example 9

[0212] Compared with Examples 11, 12, 13, 14, and 15 in terms of reaction raw materials and process, the only difference is that only gelatin (FG) is used to prepare aerogel microspheres by heating spraying method, and composites are prepared with foamed polypropylene. The preparation is as follows:

[0213] 1) Preparation of aerogel microspheres: First, dissolve 5.0 g of gelatin (FG) in 36.7 g of deionized water. Place it in a 70 °C water bath until the gelatin (FG) is completely dissolved. Then, use a heating spray bottle to spray it into a container filled with liquid nitrogen. Collect the obtained hydrogel microspheres, place them in a freeze dryer and freeze-dry for three days. Take out the obtained porous aerogel microspheres, place them in a vacuum oven at 80 °C for 24 h (to remove the un-freeze-dried bound water), take out and sieve twice (100 mesh) to obtain ternary integrated self-expanding aerogel microspheres;

[0214] 2) Preparation of composite materials: First, place the polypropylene resin in a forced-air oven and dry it at 80 °C for 12 hours. Then, add 5 wt% of microspheres, mix well, melt-extrude through a twin-screw extruder, and inject mold using an injection molding machine. Open the mold to obtain the product, that is, the composite material after injection molding.

[0215] The density of this material is 92 mg / cm 3 , the limiting oxygen index is 23%, the peak heat release is 192 kW / m 2 , the tensile strength is 14 MPa, the thermal conductivity is 188 mW / (m·K), and the pore size of the aerogel is between 3 μm and 39 μm.

[0216] Comparative Example 10

[0217] Compared with Examples 16, 17, 18, 19, and 20 in terms of reaction raw materials and process, the only difference is that: no aerogel microspheres / granules are added, and only polyimide foam is used. The preparation is as follows:

[0218] ①Compound catalyst: Add 10 g of pyridine, 1.5 g of triethanolamine, 21.5 g of dimethyl silicone oil, 100 g of deionized water, and 25 g of diethylene glycol into a 250 mL conical flask, mix and stir magnetically for half an hour until evenly dispersed for later use. ②White material: Weigh 2 g of N,N-dimethylformamide (DMF) and 1.09 g of pyromellitic dianhydride (PMDA) at room temperature in a dry 50 mL beaker, place it in a 65 °C water bath, seal the beaker mouth with plastic wrap, stir magnetically until PMDA is completely dissolved, add 2 g of ethanol to it, continue stirring for 30 minutes until the reaction is complete, cool to room temperature and then add 1.2 g of the compound catalyst, stir evenly to obtain a colorless transparent solution, which is the foaming white material. ③Black material: Add 3 g of DMF and 6 g of PMDI to a dry plastic cup and stir evenly. At this time, the solution is yellow-brown. Then add 1.55 g of 3,3′,4,4′-diphenylether tetracarboxylic dianhydride (ODPA) to it, always keep the same molar ratio of dianhydride and PMDI in the white material and the black material, continue stirring until ODPA is completely dissolved. At this time, the solution is light yellow, and the preparation of the black material is completed. ④Material preparation: After mixing the foaming white material evenly, quickly pour the black material into it to complete the foaming process, and carry out curing and heating at 80 °C for 2 hours, 120 °C for 2 hours, 150 °C for 90 minutes, 180 °C for 90 minutes, 210 °C for 60 minutes, and 230 °C for 60 minutes, that is, after thermosetting and forming, the material is obtained.

[0219] The density of this material is 68 mg / cm 3 , the limiting oxygen index is 18%, and the peak heat release is 209 kW / m 2 , the compression modulus is 1.2 MPa, and the thermal conductivity is 36.8 mW / (m·K).

[0220] Comparative Example 11

[0221] Compared with Examples 16, 17, 18, 19, and 20 in terms of reaction raw materials and process, the only difference is that: only gelatin (FG) is used to prepare aerogel microspheres by pneumatic spraying method to prepare composite materials with foamed polypropylene. The preparation is as follows:

[0222] 1) Preparation of aerogel microspheres: First, dissolve 5.0 g of gelatin (FG) in 36.7 g of deionized water, place it in a 70 °C water bath to completely dissolve the gelatin (FG), then use a pneumatic sprayer to spray it into a container filled with liquid nitrogen, collect the obtained hydrogel microspheres, place them in a freeze dryer and freeze-dry for three days, take out the freeze-dried porous aerogel microspheres, place them in a vacuum oven at 80 °C for 24 h (to remove the un-freeze-dried bound water), take out and sieve twice (100 mesh) to obtain ternary integrated self-expanding aerogel microspheres;

[0223] 2) Preparation of composite material: ① Preparation of compound catalyst: Add 10 g of pyridine, 1.5 g of triethanolamine, 21.5 g of dimethyl silicone oil, 100 g of deionized water, and 25 g of diethylene glycol into a 250 mL conical flask, mix and stir magnetically for half an hour until evenly dispersed for later use. ② White material: Weigh 2 g of N,N-dimethylformamide (DMF) and 1.09 g of pyromellitic dianhydride (PMDA) at room temperature in a dry 50 mL beaker, place it in a 65 °C water bath, seal the beaker mouth with plastic wrap, stir magnetically until PMDA is completely dissolved, add 2 g of ethanol to it, continue to stir for 30 minutes until the reaction is complete, cool to room temperature, then add 1.2 g of compound catalyst, stir evenly to obtain a colorless transparent solution, which is the foaming white material. ③ Black material: Add 3 g of DMF and 6 g of PMDI to a dry plastic cup and stir evenly. At this time, the solution is yellow-brown. Then add 1.55 g of 3,3′,4,4′-diphenylether tetracarboxylic dianhydride (ODPA) to it, and always keep the same molar ratio of dianhydride and PMDI in the white material and the black material. Continue to stir until ODPA is completely dissolved. At this time, the solution is light yellow, and the preparation of the black material is completed. ④ Material preparation: After adding 8 wt% microspheres to the foaming white material and mixing evenly, quickly pour the black material into it to complete the foaming process. After curing and heating up at 80 °C for 2 hours, 120 °C for 2 hours, 150 °C for 90 minutes, 180 °C for 90 minutes, 210 °C for 60 minutes, and 230 °C for 60 minutes, the composite material is obtained after thermosetting and forming.

[0224] The density of this material is 72 mg / cm 3 , the limiting oxygen index is 20%, the peak heat release is 199 kW / m 2 , the compressive modulus is 1.9 MPa, the thermal conductivity is 35.4 mW / (m·K), and the pore size of the aerogel is between 90 nm and 180 nm.

[0225] Comparative Example 12

[0226] Compared with Examples 16, 17, 18, 19, and 20 in terms of reaction raw materials and process, the only difference is that: only gelatin (FG) is used to prepare aerogel particles by the method of dropping with a disposable syringe, and composites are prepared with foamed polypropylene. The preparation is as follows:

[0227] 1) Preparation of aerogel particles: First, dissolve 5.0 g of gelatin (FG) in 36.7 g of deionized water, place it in a 70 °C water bath until the gelatin (FG) is completely dissolved, then use a disposable syringe to drop it into a container filled with liquid nitrogen, collect the obtained hydrogel particles, place them in a freeze dryer and freeze-dry for three days, take out the obtained porous aerogel particles, and place them in a vacuum oven at 80 °C for 24 h (to remove the un-freeze-dried bound water) to obtain ternary integrated self-expanding aerogel particles;

[0228] 2) Preparation of composite material: ① Compound catalyst: Add 10 g of pyridine, 1.5 g of triethanolamine, 21.5 g of dimethyl silicone oil, 100 g of deionized water, and 25 g of diethylene glycol into a 250 mL conical flask, mix and stir magnetically for half an hour until evenly dispersed for later use. ② White material: Weigh 2 g of N,N-dimethylformamide (DMF) and 1.09 g of pyromellitic dianhydride (PMDA) at room temperature in a dry 50 mL beaker, place it in a 65 °C water bath, seal the beaker mouth with plastic wrap, stir magnetically until PMDA is completely dissolved, add 2 g of ethanol to it, continue to stir for 30 minutes until the reaction is complete, cool to room temperature, then add 1.2 g of the compound catalyst, stir evenly to obtain a colorless transparent solution as the foaming white material. ③ Black material: Add 3 g of DMF and 6 g of PMDI into a dry plastic cup and stir evenly. At this time, the solution is yellow-brown. Then add 1.55 g of 3,3′,4,4′-diphenylether tetracarboxylic dianhydride (ODPA) to it, and always keep the same molar ratio of dianhydride and PMDI in the white material and the black material. Continue to stir until ODPA is completely dissolved. At this time, the solution is light yellow, and the preparation of the black material is completed. ④ Material preparation: After mixing the foaming white material evenly, pour the black material into it, quickly mix well, then pour it into a mold, quickly pour the rubber particles with a mass ratio of 1:1 to the foaming liquid into the mold. After waiting for the foaming process to be completed, carry out curing and heating at 80 °C for 2 hours, 120 °C for 2 hours, 150 °C for 90 minutes, 180 °C for 90 minutes, 210 °C for 60 minutes, and 230 °C for 60 minutes, that is, after thermosetting molding, the composite material is obtained.

[0229] The density of this material is 84 mg / cm 3 , the limiting oxygen index is 24%, and the peak heat release is 135 kW / m 2 , the compression modulus is 7 MPa, the thermal conductivity is 32.1 mW / (m·K), and the pore size of the aerogel is between 3 μm and 39 μm.

[0230] Table 1 Preparation conditions of each example and comparative example

[0231]

[0232]

[0233]

[0234] Note: Substrates in the table: A = rigid polyurethane foam, B = polystyrene foam, C = foamed polypropylene, D = polyimide foam; raw material A = polymer or polymer and crosslinking agent; no indicates not added

[0235] Table 2 Performance test results of samples obtained from each example and comparative example

[0236]

[0237]

[0238]

Claims

1. A method for preparing self - expanding aerogel microspheres / granules, characterized in that: It includes the following steps: mixing raw material A, a flame retardant and a solvent to prepare a precursor solution, granulating the precursor solution in an environment below -5°C to form droplet microparticles / colloidal particles, and then removing the ice crystal water in the droplet microparticles / colloidal particles to obtain the self-expanding aerogel microspheres / colloidal particles; the raw material A is: a polymer, or a polymer and a crosslinking agent.

2. The preparation method of the self-expanding aerogel microspheres / collophane according to claim 1, characterized in that: The polymer is selected from one or more of chitosan, starch, gelatin, cellulose, carboxymethyl cellulose, cellulose acetate, lignin, pectin, gellan gum, carboxymethyl chitosan, polyvinyl alcohol, polyacrylic acid, polydopamine, phenolic resin, melamine formaldehyde resin, soy protein isolate, polyacrylamide, guar gum; the crosslinking agent is selected from one or more of hydroxymethylated melamine, hydroxymethylated phenol, glutaraldehyde, formaldehyde, divalent copper salt, divalent nickel salt; the flame retardant is selected from one or more of trimethylolphosphine oxide, ammonium polyphosphate, red phosphorus, phytic acid, aminotrimethylene phosphonic acid, phenylphosphonic acid, sodium phytate, aluminum hypophosphite, melamine cyanurate, magnesium hydroxide, aluminum hydroxide. Further, when the raw material A is a polymer and a crosslinking agent, the mass ratio of the polymer, the crosslinking agent and the flame retardant is 10﹕0.5﹕0.5 to 1﹕1﹕1; when the raw material A is a polymer, the mass ratio of the polymer and the flame retardant is 10﹕0.5 to 1﹕1.

3. The preparation method of the self-expanding aerogel microspheres / corpuscles according to claim 1 or 2, characterized in that: The solvent is water; the solid content of the precursor solution is 1 to 20 wt%.

4. The preparation method of the self-expanding aerogel microspheres / granules according to any one of claims 1-3, characterized in that: The environment below -5°C is selected from liquid nitrogen, liquid helium, a cold stage, a refrigerator or a freezer; preferably liquid nitrogen.

5. The preparation method of the self-expanding aerogel microspheres / granules according to any one of claims 1-4, characterized in that: The granulation method is selected from one of manual spraying, ultrasonic spraying, heating spraying, pneumatic spraying, electric spraying, electrospinning spraying or syringe droplet method.

6. The preparation method of the self-expanding aerogel microspheres / granules according to any one of claims 1-5, characterized in that: The method for removing the ice crystal water in the droplet microparticles / colloidal particles is selected from freeze drying, vacuum drying, atmospheric drying or supercritical drying.

7. The self-expanding aerogel microspheres / colloidal particles prepared by the preparation method of the self-expanding aerogel microspheres / colloidal particles according to any one of claims 1-6.

8. Composite material, characterized in that: It is prepared by mixing the self-expanding aerogel microspheres / colloidal particles according to claim 7 with a substrate and then processing and shaping.

9. The composite material according to claim 8, wherein: The self-expanding aerogel microspheres account for 1 to 40 wt% of the total amount of the self-expanding aerogel microspheres and the substrate, or the mass ratio of the self-expanding aerogel colloidal particles to the substrate foaming liquid is 1﹕10 to 10﹕1.

10. The composite material according to claim 8 or 9, characterized in that: The substrate is selected from one of foam, adhesive, aerogel; further, the foam is selected from one of polyurethane foam, polystyrene foam, polypropylene foam, polyimide foam.

Images