Low-cost aerogel composite thermal insulation material and preparation method thereof

Abstract

The invention provides a low-cost aerogel composite thermal insulation material and a preparation method thereof. The method comprises the following steps: preparing a wet blank by using ultra-long and thin fibers, a dispersing agent, a foaming agent and a phosphate adhesive; drying the wet blank to obtain a fiber reinforced body; preparing an aerogel precursor solution by using silica sol and nano silicon dioxide powder; the high-performance aerogel composite material is prepared at a low cost by impregnating the fiber reinforcement with the precursor solution and carrying out aging, interface modification, solvent replacement and drying. The invention also provides the composite material prepared by the preparation method. According to the preparation method, the high-strength porous fibrofelt preform is prepared by taking ultra-slender fibers as a preform framework and taking a phosphate adhesive as a framework welding component through relatively low-temperature heat treatment; according to the invention, a mixed solution of silica sol and silicon dioxide nano powder is used as an aerogel precursor for coordinated regulation and interface modification, and a high-performance aerogel composite material is obtained by low-cost variable-pressure drying.

Description

Technical Field

[0001] This invention relates to the field of aerogel composite thermal insulation materials, specifically to an aerogel composite thermal insulation material with high-strength fiber felt as reinforcement and its preparation method. Background Technology

[0002] Aerogels are characterized by high temperature resistance, lightweight, and low thermal conductivity, making them a high-performance thermal insulation material with broad application prospects in aerospace, energy and power fields.

[0003] Aerogels are three-dimensional porous structures formed by the stacking of nanoparticles. The material exhibits intrinsic brittleness, making it difficult to meet the needs of practical applications.

[0004] To improve the strength of aerogel materials, researchers have reinforced and toughened aerogels using reinforcing agents such as chopped fibers, wet-laid fiber mats, and needle-punched fiber mats.

[0005] However, these reinforcements themselves lack structural integrity, and the composite material structure formed by impregnating the precursor sol has defects, making it difficult for the material's mechanical properties to meet the requirements of high-strength and high-efficiency applications in extreme environments.

[0006] To further improve the mechanical properties of aerogel materials, researchers have explored methods such as increasing the density of the preform or obtaining high-strength preforms through high-temperature sintering of fibers, thereby achieving a significant improvement in the mechanical properties of the materials.

[0007] However, the increased density of the fiber preform leads to an increase in the thermal conductivity of the material. The high-temperature sintering process not only damages the fiber structure and increases the thermal conductivity, but also increases the manufacturing cost of the material, which greatly limits its practical application.

[0008] Therefore, there is an urgent need to find a low-cost, high-performance thermal insulation material preparation technology to meet the demands of emerging extreme environments on material performance and manufacturing costs. Summary of the Invention

[0009] The purpose of this invention is to provide a new method for preparing low-cost, high-performance thermal insulation materials, which uses atmospheric pressure drying to obtain aerogel composite materials.

[0010] To achieve the above objectives, the present invention provides a method for preparing a low-cost, high-performance thermal insulation material in a first aspect, the method comprising the following steps: (1) Preparation of wet blank: Add ultrafine long fibers, dispersant and foaming agent to water and stir to disperse to obtain foam slurry. Then add phosphate binder to the foam slurry and stir evenly. Filter to obtain wet blank. (2) Preparation of fiber reinforcement: The wet preform is dried to obtain fiber reinforcement; (3) Preparation of aerogel precursor solution: The silica sol and nano silica powder are mixed and stirred evenly to obtain the aerogel precursor solution; (4) Preparation of composite material: The fiber reinforcement is impregnated with the precursor solution, and then aged, first solvent replacement, interface modification, second solvent replacement and drying are performed in sequence to obtain the composite material.

[0011] The present invention provides, in a second aspect, a composite material prepared by the preparation method described in the first aspect of the present invention.

[0012] The present invention has the following main beneficial effects: (1) The present invention selects ultra-fine long fibers as the skeleton of the preform and high-temperature resistant phosphate adhesive as the skeleton welding component, and obtains a high-strength porous fiber felt preform that can avoid sintering by heat treatment at medium and low temperature.

[0013] (2) The method of the present invention uses high-strength fiber felt as reinforcement and a mixed solution of silica sol and hollow silica nanopowder as aerogel precursor. Through the synergistic regulation of component ratio and interface modification, high-performance aerogel composite material can be obtained with low-cost pressure swing drying technology, avoiding the high energy consumption of supercritical materials and effectively reducing costs. Detailed Implementation

[0014] To make the above features and advantages of the present invention more apparent and understandable, the specific implementation of this patent is described below.

[0015] In a first aspect, this invention provides a method for preparing a low-cost, high-performance thermal insulation material, the method comprising the following steps: (1) Preparation of wet blank: Add ultrafine long fibers, dispersant and foaming agent to water and stir to disperse to obtain foam slurry. Then add phosphate binder to the foam slurry and stir evenly. Filter to obtain wet blank. (2) Preparation of fiber reinforcement: The wet preform is dried to obtain fiber reinforcement; (3) Preparation of aerogel precursor solution: The silica sol and nano silica powder are mixed and stirred evenly to obtain the aerogel precursor solution; (4) Preparation of composite material: The fiber reinforcement is impregnated with the precursor solution, and then aged, first solvent replacement, interface modification, second solvent replacement and drying are performed in sequence to obtain the composite material.

[0016] The method of the present invention will be further described step by step below.

[0017] Step (1): Preparation of wet blank In step (1), ultrafine long fibers, dispersant and foaming agent are added to water and stirred to disperse them to obtain foam slurry. Then, phosphate binder is added to the foam slurry and stirred evenly. The wet blank is obtained by vacuum filtration.

[0018] In this step, ultra-fine long fibers can be selected to construct a low-density fiber skeleton.

[0019] Preferably, the diameter of the ultrafine fibers ranges from 1 μm to 3 μm. If the fiber diameter is too small, it may not be easy to disperse effectively, and the subsequent strength may not meet the performance requirements of some applications. If the fiber diameter is too large, the density of the subsequently formed preform may be too dense, resulting in a high density of the resulting reinforcement and a high thermal conductivity.

[0020] Preferably, the length of the ultrafine fibers ranges from 0.5 cm to 2 cm.

[0021] Preferably, the ultra-fine long fibers are mullite fibers and / or quartz fibers.

[0022] In this invention, foaming agents and dispersants are selected to disperse and foam the ultrafine long fibers to ensure that the ultrafine long fibers have good overlap and pore structure.

[0023] Preferably, the dispersant is a polymer, more preferably one or more polymers selected from polyacrylamide and polyethylene oxide; Preferably, the foaming agent is an ionic surfactant, more preferably one or more ionic surfactants selected from sodium dodecylbenzenesulfonate, sodium dodecyl sulfate, dodecyltrimethylammonium chloride, and dodecyltrimethylammonium bromide.

[0024] The method of this invention uses a mixed solution of aluminum dihydrogen phosphate and aluminum sol as a binder, which can achieve effective curing and dehydration at low temperatures, thereby improving the low-temperature curing strength of the material.

[0025] Preferably, the phosphate adhesive is prepared from aluminum phosphate and nano-aluminum sol. Both aluminum phosphate and nano-aluminum sol are commercially available, with particle sizes ranging from, for example, 10 nm to 30 nm, and solid contents ranging from 5 wt% to 20 wt% (e.g., 10 wt% or 15 wt%).

[0026] More preferably, the weight ratio of aluminum phosphate to nano-aluminum sol in the phosphate adhesive is 6:4 to 9:1, for example, 7:4, 8:4, 9:4, 10:4, 20:4 or 30:4.

[0027] Preferably, the mass fraction of ultrafine long fibers in the foam slurry is 0.5% to 2% (e.g., 1% or 1.5%).

[0028] Preferably, the mass ratio of the ultrafine fibers, dispersant, and foaming agent is 100:(0.05~3):(0.01~0.1), for example, 100:(0.05, 0.1, 0.5, 1, 2, or 3):(0.01, 0.05, or 0.1). If there is too little dispersant, the fibers will not disperse easily. If too much dispersant is introduced, it may be detrimental to the control of the molding consistency of the subsequent preform. If there is too little foaming agent, it will be difficult to form a stable foam slurry; if there is too much foaming agent, it may be difficult to control the molding consistency of the material.

[0029] Preferably, the mass ratio of the phosphate adhesive to the ultrafine fibers is (3~15):100 (e.g., (3, 5, 10, or 15):100), more preferably (3~10):100, and even more preferably (5~8):100. If the amount of phosphate adhesive added is too small, it may result in fewer bonding sites, leading to insufficient strength for certain applications requiring high strength. If the amount of phosphate adhesive added is too large, it may result in an excessively large bonding area, potentially increasing the thermal conductivity of the material.

[0030] Step (2): Preparation of fiber reinforcement In this step, the wet preform is dried to obtain a fiber-reinforced material.

[0031] Preferably, the drying is gradient drying. The purpose of gradient drying is to avoid the impact damage to the structure caused by moisture evaporation, while effectively removing moisture from the adhesive through high-temperature treatment at 220°C to 280°C, thereby avoiding subsequent interference with the composite of the fiber and the precursor. A high-strength fiber reinforcement can be obtained by gradient drying, for example, by placing the wet preform in an oven. More preferably, the gradient drying method involves first drying at 70°C to 90°C (e.g., 80°C) for 12 to 18 hours (e.g., 15 hours), then drying at 120°C to 160°C (e.g., 130°C, 140°C, or 150°C) for 6 to 9 hours (e.g., 7 hours or 8 hours), and then drying at 220°C to 280°C (e.g., 230°C, 240°C, 250°C, 260°C, or 270°C) for 6 to 9 hours (e.g., 7 hours or 8 hours).

[0032] Preferably, the silica sol is an ethanol silica sol. More preferably, the particle size of the silica sol is in the range of 5 nm to 15 nm.

[0033] Preferably, the nano-silica powder is hollow nano-silica powder. More preferably, the outer diameter of the hollow nano-silica powder ranges from 100 nm to 600 nm, and the inner diameter ranges from 30 nm to 60 nm.

[0034] Preferably, the weight ratio of the silica sol to the nano-silica powder is 3:1 to 5:1 (e.g., 4:1).

[0035] Step (3): Preparation of aerogel precursor solution In this step, silica sol and nano silica powder are mixed and stirred evenly to obtain an aerogel precursor solution.

[0036] Preferably, a catalyst is added during the mixing and stirring of the silica sol and nano-silica powder. Preferably, the catalyst is an acidic catalyst, preferably hydrochloric acid or nitric acid.

[0037] Preferably, the pH of the aerogel precursor solution is adjusted to 7-8.

[0038] The total mass fraction (i.e., solid content) of silica and nano-silica powder in the aerogel precursor solution is 8% to 15% (e.g., 9%, 10%, 11%, 12%, 13%, or 14%). If the total mass fraction is too low, gelation is unlikely to occur. If the total mass fraction is too high, it may result in high thermal conductivity, and the nano-silica powder may easily settle, leading to poor system homogeneity and difficulty in controlling the gelation process.

[0039] Step (4): Preparation of composite materials In this step, the fiber reinforcement is impregnated with the precursor solution, and then subjected to aging, interface modification, solvent replacement and drying in sequence to obtain the composite material.

[0040] Preferably, the impregnation is performed using pressure impregnation. More preferably, the impregnation pressure is between 0.15 MPa and 0.25 MPa (e.g., 0.20 MPa). If the impregnation pressure is too low, it may result in uneven impregnation, and the center may be short of adhesive. If the impregnation pressure is too high, the powder may easily aggregate, causing blockage or short adhesive.

[0041] Preferably, the aging is performed at room temperature. More preferably, the aging time at room temperature is 18 to 30 hours (e.g., 24 hours).

[0042] Preferably, the interface modification is performed using an ethanol / cyclohexane solution containing an interface modifier. More preferably, the interface modifier is one or more commonly used silanizing agents selected from methyltriethoxysilane, dimethyldiethoxysilane, trimethylchlorosilane, and hexamethylenedisilazane. Further preferably, the ethanol / cyclohexane solution is a mixture of ethanol and cyclohexane in a weight ratio of 1:4 to 1:9 (e.g., 1:5, 1:6, 1:7, or 1:8). Even more preferably, the interface modification time is 18 to 30 hours (e.g., 24 hours).

[0043] Preferably, the first solvent replacement is carried out in ethanol.

[0044] Preferably, the second solvent substitution is carried out in cyclohexane.

[0045] Preferably, the mass fraction of the interface modifier in the ethanol / cyclohexane solution containing the interface modifier is 3% to 10% (e.g., 4%, 5%, 6%, 7%, 8%, or 9%). If the concentration of the interface modifier is too low, the hydrophobic effect of the system is poor, the drying shrinkage rate is large, and the thermal conductivity of the material increases. If the concentration of the interface modifier is too high, there will be too much excess in the system, which will lead to self-polymerization and increase the pressure for subsequent solvent replacement.

[0046] Preferably, the drying method is atmospheric pressure drying. More preferably, the drying is carried out as follows: first, drying at 40°C to 50°C (e.g., 45°C) for 12 to 24 hours (e.g., 18 hours), and then drying at 60°C to 70°C (e.g., 65°C) for 12 to 24 hours (e.g., 18 hours).

[0047] The preferred technical means provided in the above steps can be combined in various ways to form various technical solutions, unless otherwise stated. All of these technical solutions fall within the protection scope of this invention.

[0048] For example, the preparation method provided by the first aspect of the present invention may include a combination of certain preferred technical means described above, and includes the following steps: (1) Weigh out ultrafine long fibers and add them to water, add dispersant and foaming agent, stir and disperse into foam slurry; then add aluminum phosphate-nano aluminum sol mixed solution (for example, aluminum phosphate and nano aluminum sol are mixed at a mass ratio of 9:1), stir evenly, and filter to obtain wet blank; (2) The wet preform is placed in an oven for gradient drying to obtain a high-strength fiber reinforcement; (3) Prepare a mixed solution of silica sol (e.g., particle size range can be 5nm to 15nm) and hollow nano-silica powder (e.g., outer diameter range can be 100nm to 600nm, inner diameter range can be 30nm to 60nm), that is, add a certain mass of nano-powder to ethanol silica sol (the mass ratio of nano-powder and ethanol silica sol can be 3:1), stir evenly, add catalyst, adjust pH value to 7 to 8, and use it as aerogel precursor solution for later use; (4) The aerogel precursor solution is impregnated into the interior of the high-strength fiber reinforcement by pressure (e.g., using a pressure of 0.15 MPa to 0.25 MPa). After impregnation (this process is also called "gel injection"), it is aged at room temperature for 24 hours. Then, an ethanol / cyclohexane solution containing an interface modifying agent is added to modify the interface of the wet gel. After 24 hours of modification, it is taken out and placed in cyclohexane solvent for replacement. Finally, the composite material is obtained by drying.

[0049] The present invention provides, in a second aspect, a composite material prepared by the preparation method described in the first aspect of the present invention.

[0050] The present invention will be further described below by way of examples, but the scope of protection of the present invention is not limited to these embodiments.

[0051] Unless otherwise specified, the aluminum phosphate-nano aluminum sol mixed solution (particle size range of 10nm to 30nm, solid content of 10% by weight) used in the embodiments of this application is a solution obtained by mixing aluminum phosphate and nano aluminum sol in a weight ratio of 9:1; the dispersant is polyacrylamide; the foaming agent is sodium dodecylbenzenesulfonate; the volume ratio of ethanol to cyclohexane in the ethanol / cyclohexane solution is 1:4; the outer diameter of the hollow nano silica powder ranges from 100nm to 600nm, and the inner diameter ranges from 30nm to 60nm.

[0052] Example 1 (1) Weigh 100g of ultrafine (fiber diameter range of 1μm to 3μm, length range of 0.5cm to 2cm) quartz long fibers and add them to 20kg of water. Add 0.05g of dispersant and 1g of foaming agent and stir to disperse into foam slurry. Then, add 15g of aluminum phosphate-nano aluminum sol (9:1) mixed solution, stir evenly, and filter to obtain wet blank.

[0053] (2) The wet preform is placed in an oven for gradient drying, i.e., drying at 90℃ for 12 hours, drying at 150℃ for 6 hours, and drying at 220℃ for 6 hours to obtain a dried high-strength fiber reinforcement.

[0054] (3) Add 50g of hollow nano silica powder with a particle size range of 100nm to 600nm to 1000g of silica sol with a silica mass fraction of 10% (i.e., the amount of silica is 100g), add ethanol to dilute to a solid content (i.e., the total weight percentage of silica in silica sol and hollow nano silica powder) of 8%, stir evenly, add acidic catalyst (hydrochloric acid) to adjust the pH value to 7~8, and obtain aerogel precursor solution.

[0055] (4) The high-strength fiber reinforcement is placed in a molding mold. After the mold is closed, the precursor solution is injected into the fiber reinforcement by pressure impregnation (0.15MPa pressure). After the injection is completed, the product is aged at room temperature for 24 hours. Then, the aged product is placed in ethanol for solvent replacement, and then placed in an ethanol / cyclohexane solution containing 10% methyltriethoxysilane for modification. After 24 hours of modification, the product is taken out and placed in cyclohexane solvent for replacement. Finally, it is dried at 40°C for 12 hours and then dried at 60°C for 12 hours to obtain the composite material.

[0056] Example 2 (1) Weigh 100g of ultrafine (fiber diameter range of 1μm to 3μm, length range of 0.5cm to 2cm) mullite long fibers and add them to 5kg of water. Add 3g of dispersant (polyethylene oxide) and 0.1g of foaming agent (dodecyltrimethylammonium chloride) and stir to disperse into a foam slurry. Then, add 5g of aluminum phosphate-nano aluminum sol (9:1) mixed solution, stir evenly, and filter to obtain wet blank.

[0057] (2) The wet preform is placed in an oven for gradient drying, i.e., drying at 90℃ for 12 hours, drying at 150℃ for 6 hours, and drying at 220℃ for 6 hours to obtain a dried high-strength fiber reinforcement.

[0058] (3) Add 50g of hollow nano silica powder with a particle size range of 100nm to 600nm to 1000g of silica sol solution with a mass fraction of 10% (i.e., the amount of silica is 100g), add ethanol to dilute to a solid content of 10%, stir evenly, add acidic catalyst (nitric acid) to adjust the pH value to 7~8, and obtain aerogel precursor solution.

[0059] (4) The high-strength fiber reinforcement is placed in a molding mold. After the mold is closed, the precursor solution is injected into the fiber reinforcement by pressure impregnation (0.25 MPa pressure). After the injection is completed, the product is aged at room temperature for 24 hours. Then, the aged product is placed in ethanol for solvent replacement, and then placed in an ethanol / cyclohexane solution containing 15% dimethyldiethoxysilane for modification. After 24 hours of modification, the product is taken out and placed in cyclohexane solvent for replacement. Finally, it is dried at 40°C for 12 hours and then dried at 60°C for 12 hours to obtain the composite material.

[0060] Example 3 (1) Weigh 100g of ultrafine (fiber diameter range of 1μm to 3μm, length range of 0.5cm to 2cm) quartz long fibers and add them to 10kg of aqueous solution. Add 2g of dispersant and 0.5g of foaming agent and stir to disperse into foam slurry. Then, add 10g of aluminum phosphate-nano aluminum sol (9:1) mixed solution, stir evenly, and filter to obtain wet blank.

[0061] (2) The wet preform is placed in an oven for gradient drying, i.e., drying at 90℃ for 12 hours, drying at 150℃ for 6 hours, and drying at 220℃ for 6 hours to obtain a dried high-strength fiber reinforcement.

[0062] (3) Add 50g of hollow nano silica powder with a particle size range of 100nm to 600nm to 1000g of silica sol solution with a mass fraction of 10% (i.e., the amount of silica is 100g), add ethanol to dilute to a solid content of 10%, stir evenly, add acidic catalyst (hydrochloric acid) to adjust the pH value to 7~8, and obtain aerogel precursor solution.

[0063] (4) The high-strength fiber reinforcement is placed in the molding mold. After the mold is closed, the precursor solution is injected into the fiber reinforcement by pressure impregnation (0.2MPa pressure). After the injection is completed, it is aged at room temperature for 24 hours. Then, the aged product is placed in ethanol for solvent replacement, and then placed in an ethanol / cyclohexane solution containing 10% methyltriethoxysilane for modification. After 24 hours of modification, it is taken out and placed in cyclohexane solvent for replacement. Finally, it is dried at 40℃ for 12 hours and then dried at 60℃ for 12 hours to obtain the composite material.

[0064] Example 4 (1) Weigh 100g of ultrafine (fiber diameter range of 1μm to 3μm, length range of 0.5cm to 2cm) quartz long fibers and add them to 10kg of water. Add 2g of dispersant and 0.5g of foaming agent and stir to disperse into foam slurry. Then, add 10g of aluminum phosphate-nano aluminum sol (9:1) mixed solution, stir evenly, and filter to obtain wet blank.

[0065] (2) The wet preform is placed in an oven for gradient drying, i.e., drying at 90℃ for 12 hours, drying at 150℃ for 6 hours, and drying at 220℃ for 6 hours to obtain a dried high-strength fiber reinforcement.

[0066] (3) Add 100g of hollow nano silica powder with a particle size range of 100nm to 600nm to 1000g of silica sol solution with a mass fraction of 10% (i.e., the amount of silica is 100g), add ethanol to dilute to a solid content of 15%, stir evenly, add acidic catalyst (hydrochloric acid) to adjust the pH value to 7~8, and obtain aerogel precursor solution.

[0067] (4) The high-strength fiber reinforcement is placed in the molding mold. After the mold is closed, the precursor solution is injected into the fiber reinforcement by pressure impregnation (0.2MPa pressure). After the injection is completed, it is aged at room temperature for 24 hours. Then, the aged product is placed in ethanol for solvent replacement, and then placed in an ethanol / cyclohexane solution containing 10% methyltriethoxysilane for modification. After 24 hours of modification, it is taken out and placed in cyclohexane solvent for replacement. Finally, it is dried at 40℃ for 12 hours and then dried at 60℃ for 12 hours to obtain the composite material.

[0068] Comparative Example 1 (1) Weigh 100g of ultrafine (fiber diameter range of 1μm to 3μm, length range of 0.5cm to 2cm) quartz long fibers and add them to 10kg of water. Add 2g of dispersant and 0.5g of foaming agent and stir to disperse into foam slurry. Then, add 10g of aluminum phosphate-nano aluminum sol (9:1) mixed solution, stir evenly, and filter to obtain wet blank.

[0069] (2) The wet preform is placed in an oven for gradient drying, i.e., drying at 90℃ for 12 hours, drying at 150℃ for 6 hours, and drying at 220℃ for 6 hours to obtain a dried high-strength fiber reinforcement.

[0070] (3) Add 100g of hollow nano silica powder with a particle size range of 100nm to 600nm to 1000g of silica sol solution with a mass fraction of 10% (i.e., the amount of silica is 100g), stir evenly, add acidic catalyst (hydrochloric acid) to adjust the pH value to 7~8, and obtain aerogel precursor solution.

[0071] (4) Place the high-strength fiber reinforcement in the molding mold. After the mold is closed, inject the precursor solution into the fiber reinforcement by pressure impregnation (0.2MPa pressure). After the injection is completed, age at room temperature for 24 hours. Then, place the aged product in ethanol for solvent replacement, and then place it in an ethanol / cyclohexane solution containing 10% methyltriethoxysilane for modification. After 24 hours of modification, take it out and place it in cyclohexane solvent for replacement. Finally, dry it at 40℃ for 12 hours and then at 60℃ for 12 hours to obtain the composite material.

[0072] Comparative Example 2 (1) Weigh 100g of ultrafine (fiber diameter range of 1μm to 3μm, length range of 0.5cm to 2cm) quartz long fibers and add them to 10kg of water. Add 2g of dispersant and 0.5g of foaming agent and stir to disperse into foam slurry. Then, add 30g of aluminum phosphate-nano aluminum sol (9:1) mixed solution, stir evenly, and filter to obtain wet blank.

[0073] (2) The wet preform is placed in an oven for gradient drying, i.e., drying at 90℃ for 12 hours, drying at 150℃ for 6 hours, and drying at 220℃ for 6 hours to obtain a dried high-strength fiber reinforcement.

[0074] (3) Add 50g of hollow nano silica powder with a particle size range of 100nm to 600nm to 1000g of silica sol solution with a mass fraction of 10% (i.e., the amount of silica is 100g), add ethanol to dilute to a solid content of 10%, stir evenly, add acidic catalyst (hydrochloric acid) to adjust the pH value to 7~8, and obtain aerogel precursor solution.

[0075] (4) Place the high-strength fiber reinforcement in the molding mold. After the mold is closed, inject the precursor solution into the fiber reinforcement by pressure impregnation (0.2MPa pressure). After the injection is completed, age at room temperature for 24 hours. Then, place the aged product in ethanol for solvent replacement, and then place it in an ethanol / cyclohexane solution containing 10% methyltriethoxysilane for modification. After 24 hours of modification, take it out and place it in cyclohexane solvent for replacement. Finally, dry it at 40℃ for 12 hours and then at 60℃ for 12 hours to obtain the composite material.

[0076] Comparative Example 3 (1) Weigh 100g of ultrafine (fiber diameter range of 1μm to 3μm, length range of 0.5cm to 2cm) quartz long fibers and add them to 10kg of water. Add 2g of dispersant and stir to disperse into fiber slurry. Then, add 10g of aluminum phosphate-nano aluminum sol (9:1) mixed solution, stir evenly, and filter to obtain wet blank.

[0077] (2) The wet preform is placed in an oven for gradient drying, i.e., drying at 90℃ for 12 hours, drying at 150℃ for 6 hours, and drying at 220℃ for 6 hours to obtain a dried high-strength fiber reinforcement.

[0078] (3) Add 50g of hollow nano silica powder with a particle size range of 100nm to 600nm to 1000g of silica sol solution with a mass fraction of 10% (i.e., the amount of silica is 100g), add ethanol to dilute to a solid content of 10%, stir evenly, add acidic catalyst (hydrochloric acid) to adjust the pH value to 7~8, and obtain aerogel precursor solution.

[0079] (4) Place the high-strength fiber reinforcement in the molding mold. After the mold is closed, inject the precursor solution into the fiber reinforcement by pressure impregnation (0.2MPa pressure). After the injection is completed, age at room temperature for 24 hours. Then, place the aged product in ethanol for solvent replacement, and then place it in an ethanol / cyclohexane solution containing 10% methyltriethoxysilane for modification. After 24 hours of modification, take it out and place it in cyclohexane solvent for replacement. Finally, dry it at 40℃ for 12 hours and then at 60℃ for 12 hours to obtain the composite material.

[0080] Comparative Example 4 (1) Weigh 100g of ultrafine (fiber diameter range of 1μm to 3μm, length range of 0.5cm to 2cm) quartz long fibers and add them to 10kg of water. Add 2g of foaming agent and stir to disperse into foam slurry. Then, add 10g of aluminum phosphate-nano aluminum sol (9:1) mixed solution, stir evenly, and filter to obtain wet blank.

[0081] (2) The wet preform is placed in an oven for gradient drying, i.e., drying at 90℃ for 12 hours, drying at 150℃ for 6 hours, and drying at 220℃ for 6 hours to obtain a dried high-strength fiber reinforcement.

[0082] (3) Add 50g of hollow nano silica powder with a particle size range of 100nm to 600nm to 1000g of silica sol solution with a mass fraction of 10% (i.e., the amount of silica is 100g), add ethanol to dilute to a solid content of 10%, stir evenly, add acidic catalyst (hydrochloric acid) to adjust the pH value to 7~8, and obtain aerogel precursor solution.

[0083] (4) Place the high-strength fiber reinforcement in the molding mold. After the mold is closed, inject the precursor solution into the fiber reinforcement by pressure impregnation (0.2MPa pressure). After the injection is completed, age at room temperature for 24 hours. Then, place the aged product in ethanol for solvent replacement, and then place it in an ethanol / cyclohexane solution containing 10% methyltriethoxysilane for modification. After 24 hours of modification, take it out and place it in cyclohexane solvent for replacement. Finally, dry it at 40℃ for 12 hours and then at 60℃ for 12 hours to obtain the composite material.

[0084] Comparative Example 5 (1) Weigh 100g of ultrafine (fiber diameter range of 1μm to 3μm, length range of 0.5cm to 2cm) quartz long fibers and add them to 10kg of water. Add 0.05g of dispersant and 1g of foaming agent and stir to disperse into foam slurry. Then, add 10g of aluminum phosphate-nano aluminum sol (9:1) mixed solution, stir evenly, and filter to obtain wet blank.

[0085] (2) The wet preform is placed in an oven for gradient drying, i.e., drying at 90℃ for 12 hours, drying at 150℃ for 6 hours, and drying at 220℃ for 6 hours to obtain a dried high-strength fiber reinforcement.

[0086] (3) Add 50g of hollow nano silica powder with a particle size range of 100nm to 600nm to 1000g of silica sol solution with a mass fraction of 10% (i.e., the amount of silica is 100g), add ethanol to dilute to a solid content of 10%, stir evenly, add acidic catalyst (hydrochloric acid) to adjust the pH value to 7~8, and obtain aerogel precursor solution.

[0087] (4) Place the high-strength fiber reinforcement in the molding mold. After the mold is closed, inject the precursor solution into the fiber reinforcement by pressure impregnation (0.35MPa pressure). After the injection is completed, age at room temperature for 24 hours. Then, place the aged product in ethanol for solvent replacement, and then place it in an ethanol / cyclohexane solution containing 10% methyltriethoxysilane for modification. After 24 hours of modification, take it out and place it in cyclohexane solvent for replacement. Finally, dry it at 40℃ for 12 hours and then at 60℃ for 12 hours to obtain the composite material.

[0088] Comparative Example 6 (1) Weigh 100g of ultrafine (fiber diameter range of 1μm to 3μm, length range of 0.5cm to 2cm) quartz long fibers and add them to 10kg of water. Add 0.05g of dispersant and 1g of foaming agent and stir to disperse into foam slurry. Then, add 10g of aluminum phosphate-nano aluminum sol (9:1) mixed solution, stir evenly, and filter to obtain wet blank.

[0089] (2) The wet preform is placed in an oven for gradient drying, i.e., drying at 90℃ for 12 hours, drying at 150℃ for 6 hours, and drying at 220℃ for 6 hours to obtain a dried high-strength fiber reinforcement.

[0090] (3) Add 50g of hollow nano silica powder with a particle size range of 100nm to 600nm to 1000g of silica sol solution with a mass fraction of 10% (i.e., the amount of silica is 100g), add ethanol to dilute to a solid content of 10%, stir evenly, add acidic catalyst (hydrochloric acid) to adjust the pH value to 7~8, and obtain aerogel precursor solution.

[0091] (4) Place the high-strength fiber reinforcement in the molding mold. After the mold is closed, inject the precursor solution into the fiber reinforcement by pressure impregnation (0.2MPa pressure). After the injection is completed, age at room temperature for 24 hours. Then, place the aged product in ethanol for solvent replacement, and then place it in a solution containing ethanol / cyclohexane for modification. After 24 hours of modification, take it out and place it in cyclohexane solvent for replacement. Finally, dry it at 40℃ for 12 hours and then at 60℃ for 12 hours to obtain the composite material.

[0092] Comparative Example 7 (1) Weigh 100g of ultrafine (fiber diameter range of 1μm to 3μm, length range of 0.5cm to 2cm) quartz long fibers and add them to 10kg of water. Add 0.05g of dispersant and 1g of foaming agent and stir to disperse into foam slurry. Then, add 10g of aluminum phosphate-nano aluminum sol (9:1) mixed solution, stir evenly, and filter to obtain wet blank.

[0093] (2) The wet preform is placed in an oven for gradient drying, i.e., drying at 90℃ for 12 hours, drying at 150℃ for 6 hours, and drying at 220℃ for 6 hours to obtain a dried high-strength fiber reinforcement.

[0094] (3) Add 50g of hollow nano silica powder with a particle size range of 100nm to 600nm to 1000g of silica sol solution with a mass fraction of 10% (i.e., the amount of silica is 100g), add ethanol to dilute to a solid content of 10%, stir evenly, add acidic catalyst (hydrochloric acid) to adjust the pH value to 7~8, and obtain aerogel precursor solution.

[0095] (4) Place the high-strength fiber reinforcement in the molding mold. After the mold is closed, inject the precursor solution into the fiber reinforcement by pressure impregnation (0.2MPa pressure). After the injection is completed, age at room temperature for 24 hours. Then, place the aged product in ethanol for solvent replacement, and then place it in an ethanol / cyclohexane solution containing 10% methyltriethoxysilane for modification. After 24 hours of modification, take it out and place it in cyclohexane solvent for replacement. Finally, dry at 70℃ for 24 hours to obtain the composite material.

[0096] Comparative Example 8 (1) Weigh 100g of ultrafine (fiber diameter range of 1μm to 3μm, length range of 0.5cm to 2cm) quartz long fibers and add them to 10kg of water. Add 2g of dispersant and 0.5g of foaming agent, stir and disperse into foam slurry, and filter to obtain wet blank.

[0097] (2) The wet preform is placed in an oven for gradient drying, i.e., drying at 90℃ for 12 hours, drying at 150℃ for 6 hours, and drying at 220℃ for 6 hours to obtain the dried fiber reinforcement.

[0098] (3) Add 50g of hollow nano silica powder with a particle size range of 100nm to 600nm to 1000g of silica sol solution with a mass fraction of 10% (i.e., the amount of silica is 100g), add ethanol to dilute to a solid content of 10%, stir evenly, add acidic catalyst (hydrochloric acid) to adjust the pH value to 7~8, and obtain aerogel precursor solution.

[0099] (4) The fiber reinforcement is placed in the molding mold. After the mold is closed, the precursor solution is injected into the fiber reinforcement by pressure impregnation (0.2MPa pressure). After the injection is completed, it is aged at room temperature for 24 hours. Then, the aged product is placed in ethanol for solvent replacement, and then placed in an ethanol / cyclohexane solution containing 10% methyltriethoxysilane for modification. After 24 hours of modification, it is taken out and placed in cyclohexane solvent for replacement. Finally, it is dried at 40℃ for 12 hours and then dried at 60℃ for 12 hours to obtain the composite material.

[0100] Comparative Example 9 (1) Weigh 100g of short-cut quartz fibers (fiber diameter range 4-8μm, length range 0.5cm to 2cm) with a length of 4mm and add them to 10kg of water. Add 2g of dispersant and 0.5g of foaming agent and stir to disperse into a foam slurry. Then, add 10g of aluminum phosphate-nano aluminum sol (9:1) mixed solution, stir evenly, and filter to obtain wet blank.

[0101] (2) The wet preform is placed in an oven for gradient drying, i.e., drying at 90℃ for 12 hours, drying at 150℃ for 6 hours, and drying at 220℃ for 6 hours to obtain a dried high-strength fiber reinforcement.

[0102] (3) Add 100g of hollow nano silica powder with a particle size range of 100nm to 600nm to 1000g of silica sol solution with a mass fraction of 10% (i.e., the amount of silica is 100g), add ethanol to dilute to a solid content of 15%, stir evenly, add acidic catalyst (hydrochloric acid) to adjust the pH value to 7~8, and obtain aerogel precursor solution.

[0103] (4) The high-strength fiber reinforcement is placed in the molding mold. After the mold is closed, the precursor solution is injected into the fiber reinforcement by pressure impregnation (0.2MPa pressure). After the injection is completed, it is aged at room temperature for 24 hours. Then, the aged product is placed in ethanol for solvent replacement, and then placed in an ethanol / cyclohexane solution containing 10% methyltriethoxysilane for modification. After 24 hours of modification, it is taken out and placed in cyclohexane solvent for replacement. Finally, it is dried at 40℃ for 12 hours and then dried at 60℃ for 12 hours to obtain the composite material.

[0104] Comparative Example 10 (1) Weigh 100g of ultrafine (fiber diameter range of 1μm to 3μm, length range of 0.5cm to 2cm) quartz long fibers and add them to 10kg of water. Add 2g of dispersant and 0.5g of foaming agent and stir to disperse into foam slurry. Then, add 10g of aluminum phosphate-nano aluminum sol (9:1) mixed solution, stir evenly, and filter to obtain wet blank.

[0105] (2) The wet preform is placed in an oven for gradient drying, i.e., drying at 90℃ for 12 hours, drying at 150℃ for 6 hours, and drying at 220℃ for 6 hours to obtain the dried fiber reinforcement.

[0106] (3) Weigh 1000g of silica sol solution with a mass fraction of 10% (i.e., the amount of silica is 100g), add acidic catalyst (hydrochloric acid) to adjust the pH value to 7~8, stir evenly to obtain aerogel precursor solution.

[0107] (4) The fiber reinforcement is placed in the molding mold. After the mold is closed, the precursor solution is injected into the fiber reinforcement by pressure impregnation (0.2MPa pressure). After the injection is completed, it is aged at room temperature for 24 hours. Then, the aged product is placed in ethanol for solvent replacement, and then placed in an ethanol / cyclohexane solution containing 10% methyltriethoxysilane for modification. After 24 hours of modification, it is taken out and placed in cyclohexane solvent for replacement. Finally, it is dried at 40℃ for 12 hours and then dried at 60℃ for 12 hours to obtain the composite material.

[0108] The thermal conductivity and strength of the materials prepared in the examples and comparative examples were characterized, and the specific results are shown in Table 1 below.

[0109] Table 1. Properties of the composite materials obtained in each embodiment and comparative example Note: Comparative Example 5 has uneven glue application, poor material performance consistency, and low reliability of test data, so it is indicated by "-".

[0110] As shown in Table 1, compared to the comparative material, the material prepared in this example exhibits higher strength and lower thermal conductivity, combining mechanical strength with high thermal resistance. Given the low energy consumption of its preparation method, the preparation of a low-cost, high-performance thermal insulation material has been successfully achieved.

[0111] The parts of this invention not described in detail are techniques known to those skilled in the art.

[0112] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a low-cost aerogel composite thermal insulation material, characterized in that, The method includes the following steps: (1) Preparation of wet blank: Add ultrafine long fibers, dispersant and foaming agent to water and stir to disperse to obtain foam slurry. Then add phosphate binder to the foam slurry and stir evenly. Filter to obtain wet blank. (2) Preparation of fiber reinforcement: The wet preform is dried to obtain fiber reinforcement; (3) Preparation of aerogel precursor solution: The silica sol and nano silica powder are mixed and stirred evenly to obtain the aerogel precursor solution; (4) Preparation of composite material: The fiber reinforcement is impregnated with the precursor solution, and then aged, first solvent replacement, interface modification, second solvent replacement and drying are performed in sequence to obtain the composite material.

2. The preparation method according to claim 1, characterized in that, In step (1): The ultra-fine long fiber has a fiber diameter of 1 μm to 3 μm, and / or the length of the ultra-fine long fiber ranges from 0.5 cm to 2 cm; The foaming agent is an ionic surfactant, preferably selected from one or more of sodium dodecylbenzenesulfonate, sodium dodecyl sulfate, dodecyltrimethylammonium chloride, and dodecyltrimethylammonium bromide; and / or The phosphate adhesive is prepared from aluminum phosphate and nano-aluminum sol. Preferably, the weight ratio of aluminum phosphate to nano-aluminum sol in the phosphate adhesive is 6:4 to 9:

1.

3. The preparation method according to claim 1, characterized in that, In step (1): The mass fraction of the ultrafine long fibers is 0.5% to 2% based on the amount of water used; The mass ratio of the ultrafine long fibers, dispersant, and foaming agent is 100:(0.05~3):(0.01~0.1); and / or The mass ratio of the phosphate adhesive to the ultrafine long fiber is (3~15):100, preferably (5~8):

100.

4. The preparation method according to claim 1, characterized in that, In step (2): The drying process is gradient drying. Preferably, the gradient drying method involves first drying at 70°C to 90°C for 12 to 18 hours, then drying at 120°C to 160°C for 6 to 9 hours, and finally drying at 220°C to 280°C for 6 to 9 hours.

5. The preparation method according to claim 1, characterized in that, In step (3): The particle size of the silica sol is 5 nm to 15 nm; The nano-silica powder is a hollow nano-silica powder. Preferably, the outer diameter of the hollow nano-silica powder ranges from 100 nm to 600 nm, and the inner diameter ranges from 30 nm to 60 nm; and / or The weight ratio of the silica sol to the nano-silica powder is 3:1 to 5:

1.

6. The preparation method according to claim 1, characterized in that, In step (3): When a catalyst is added during stirring, it is preferred that the catalyst is an acidic catalyst, preferably hydrochloric acid or nitric acid. Preferably, the pH of the aerogel precursor solution is adjusted to 7-8; More preferably, the total mass fraction of silica and nano-silica powder in the aerogel precursor solution is 8% to 15%.

7. The preparation method according to claim 1, characterized in that, In step (4): The impregnation is carried out by pressure impregnation, preferably with an impregnation pressure of 0.15 MPa to 0.25 MPa; The aging process is at room temperature, preferably for 18 to 30 hours; and / or The interface modification is performed using an ethanol / cyclohexane solution containing an interface modifier. Preferably, the interface modifier is a silanizing agent, more preferably one or more selected from methyltriethoxysilane, dimethyldiethoxysilane, trimethylchlorosilane, and hexamethylenedisilazane. It is also preferred that the ethanol / cyclohexane solution is a mixed solution of ethanol and cyclohexane in a volume ratio of 1:4 to 1:

9. More preferably, the interface modification time is 18 to 30 hours.

8. The preparation method according to claim 1, characterized in that, In step (4): The mass fraction of the interface modifier in the ethanol / cyclohexane solution containing the interface modifier is 3% to 10%.

9. The preparation method according to claim 1, characterized in that, In step (4): The drying method is atmospheric pressure drying. Preferably, the drying is carried out as follows: first, drying at 40°C to 50°C for 12 to 24 hours, and then drying at 60°C to 70°C for 12 to 24 hours.

10. The composite material prepared by any one of claims 1 to 9.

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