Modified silica aerogel powder and manufacturing method, aerogel slurry and manufacturing method and application

Abstract

The present invention provides a modified silica aerogel powder having a higher water repellency and a larger contact angle, and a method for producing the same. At the same time, the present invention provides an aerogel slurry having a lower thermal conductivity and a method for producing the same. The present invention also provides a method for producing an aerogel insulating felt having low thermal conductivity, high mechanical strength, and capable of relatively well resolving the problem of powder shedding. The method for producing the modified silica aerogel powder includes the steps of (1) modifying halloysite nanotubes with dodecyl methacrylate and pentafluorophenyl methacrylate, (2) preparing a silica sol, (3) adding the modified halloysite nanotubes to the silica sol to prepare a wet gel, and (5) preparing the wet gel into the modified silica aerogel powder. The present application also provides a method for producing an aerogel slurry from the modified silica aerogel powder, and a method for producing an aerogel insulating felt from the aerogel slurry.

Description

[Technical Field]

[0001] The present application relates to the technical field of heat insulating material manufacturing, in particular to modified silica aerogel powder and manufacturing method, aerogel slurry and manufacturing method and application. [Background technology]

[0002] Silica aerogel is a lightweight nano-amorphous solid material. As an emerging super thermal insulation material, it has extremely low thermal conductivity, much lower than the thermal conductivity of static air at room temperature, which is 0.25 W / m·K. It has incomparable thermal insulation and heat retention properties compared to other materials. It also has low density, is waterproof, flame retardant, green, environmentally friendly, corrosion-resistant, aging-resistant, and has a long service life, making it known as a super thermal insulation material.

[0003] Slurry molding is a new solution for combining silica aerogel with fiber materials. It involves mixing prefabricated nanopowder with a solvent to produce a slurry, which is then infused into a prefabricated fiber fabric. The solvent is then removed from the fabric to form a fiber-reinforced aerogel composite. Taking advantage of the low cost and excellent compatibility between the slurry and fiber, the slurry can be combined with various fiber felts (e.g., glass fiber felt, quartz fiber felt, alumina fiber felt, and mullite fiber felt) to produce aerogel composite insulation felts that combine flexibility and excellent mechanical properties.

[0004] The composite insulation felt produced by the conventional slurry molding method also has problems such as relatively high thermal conductivity, poor mechanical strength, and inability to withstand high temperatures, etc. Therefore, it is of great practical significance to realize the rapid and low-cost production of silica aerogel composite insulation felt, while providing the material with flexibility, good mechanical properties, excellent insulation performance, and high-temperature resistance. Summary of the Invention [Problem to be solved by the invention]

[0005] To solve the above technical problems, a modified silica aerogel powder with a higher water repellency and a larger contact angle has been developed, and at the same time, an aerogel slurry with a lower thermal conductivity has been developed. After combining with a fiber felt, the aerogel insulation felt produced can meet the requirements of low thermal conductivity, high mechanical strength, and relatively well solving the problem of powder shedding. This application provides a modified silica aerogel powder and a manufacturing method, an aerogel slurry and a manufacturing method, and applications thereof. [Means for solving the problem]

[0006] According to a first aspect, the present application provides a method for producing a modified silica aerogel powder, comprising: Step S1: adding dodecyl methacrylate, pentafluorophenyl methacrylate, an organic solvent and halloysite nanotubes into a reaction vessel, adding an initiator, controlling the reaction temperature at 70-80°C, reacting for 4-8 hours with stirring, cooling, filtering to remove the filtration residue, washing, and drying to prepare copolymer-modified halloysite nanotubes for use; Step S2: mixing and stirring a silicon source, deionized water, absolute ethanol, and n-hexane at room temperature to prepare a silicon source precursor solution; Step S3 of adding an acid catalyst to the silicon source precursor solution prepared in step S2, adjusting the pH of the solution to 2 to 3, and carrying out a hydrolysis reaction under heating in a water bath to prepare a silica sol; Step S4: adding a basic catalyst to the silica sol prepared in step S3, adjusting the pH of the solution to 6-7, adding the copolymer-modified halloysite nanotubes prepared in step S1, stirring and ultrasonicating, adding diphenylmethane diisocyanate and an organotin catalyst, reacting at 50-60°C for 8-15 hours, and then leaving to stand to prepare a wet gel. Step S5 includes aging the wet gel produced in step S4, controlling the aging time to 10-15 hours, adding a hydrophobic modifier to perform hydrophobic modification, drying, and ball milling to produce modified silica aerogel powder.

[0007] Optionally, in step S1, the weight ratio of dodecyl methacrylate, pentafluorophenyl methacrylate, initiator and halloysite nanotubes is (5-10):(2-3):(0.2-0.5):(50-80).

[0008] Optionally, in step S1, the halloysite nanotubes are coupling-modified halloysite nanotubes, and the preparation process of the coupling-modified halloysite nanotubes includes the steps of: mixing the halloysite nanotubes with a urea solution, ultrasonicating, standing, then adding sulfuric acid, standing, filtering, and drying to prepare pre-treated halloysite nanotubes; and adding a silane coupling agent, water, and the pre-treated halloysite nanotubes to a reaction vessel, adjusting the pH to 9-10, reacting at 60-80°C for 2-3 hours, adjusting the pH to neutral, cooling, filtering, washing the filtration residue, and drying to prepare coupling-modified halloysite nanotubes.

[0009] Optionally, in step S1, the process for producing the pretreated halloysite nanotubes includes mixing halloysite nanotubes in a weight ratio of 1:(8-10) with a 20 wt% urea solution, ultrasonicating, allowing to stand, then adding a 5 wt% sulfuric acid solution, allowing to stand, filtering, and drying to produce pretreated halloysite nanotubes, wherein the weight ratio of the sulfuric acid solution to the halloysite nanotubes is 5:1.

[0010] Optionally, in step S1, the process for preparing the coupling-modified halloysite nanotubes includes adding a silane coupling agent, water, and pre-treated halloysite nanotubes to a reaction vessel, adjusting the pH to 9-10, reacting at 60-80°C for 2-3 hours, adjusting the pH to neutral, cooling, filtering, washing the filtration residue, and drying to prepare the coupling-modified halloysite nanotubes, in which the weight ratio of the silane coupling agent, water, and pre-treated halloysite nanotubes is (1-1.5):100:(9-14).

[0011] By adopting the above technical solution, urea, as a polar solvent, can help open the cavities of the halloysite nanotubes, strengthen the insulating ability of the halloysite nanotubes, and increase their internal surface area. At the same time, the insertion of urea molecules may change the surface properties of the halloysite nanotubes, improving their dispersibility and reactivity. Acid treatment of halloysite nanotubes will first lead to the removal of some hydroxyl groups, but will also promote the rehydroxylation of the halloysite nanotube surface, thereby generating more hydroxyl groups on the halloysite nanotube surface and providing more reactive sites for subsequent functionalization.

[0012] Optionally, in step S2, the weight ratio of the silicon source, deionized water, absolute ethanol, and n-hexane is 1:(5-10):(3-6):(1-2).

[0013] Optionally, in step S2, the silicon source is one or more selected from n-methyl silicate, n-ethyl silicate, sodium silicate, n-isopropyl silicate, methyltrimethoxysilane, and methyltriethoxysilane.

[0014] Optionally, in step S3, the acid catalyst is one of an oxalic acid solution, a hydrochloric acid solution, a phosphoric acid solution and a citric acid solution, and has a concentration of 0.3 to 0.5 wt %.

[0015] Optionally, in step S4, the basic catalyst is one of an aqueous ammonia solution, a sodium carbonate solution, and a sodium bicarbonate solution, and has a concentration of 0.2 to 0.4 wt %.

[0016] Optionally, in step S4, the weight ratio of silica sol, copolymer-modified halloysite nanotubes, diphenylmethane diisocyanate and organotin catalyst is (20-30):(1-3):(0.5-1):0.05.

[0017] Optionally, in step S6, the hydrophobic modifier is trimethylchlorosilane.

[0018] Optionally, in step S6, the hydrophobic modifier is a mixed liquid of n-hexane and trimethylchlorosilane with a weight ratio of (7-12):1.

[0019] By adopting the above technical solution, trimethylchlorosilane is mixed with n-hexane before being used for hydrophobic modification, which can prevent the wet gel from reacting too violently during the hydrophobic treatment process and causing the gel to break apart, thereby ensuring the surface performance of the produced aerogel.

[0020] Optionally, in step S5, the drying process is performed by vacuum freeze drying, with the temperature being (-60) to (-30)°C, the vacuum being 50 to 100 Pa, and the drying time being 10 to 30 hours.

[0021] By adopting the above technical solution, the present application grafts a copolymer of dodecyl methacrylate and pentafluorophenyl methacrylate onto the surface of halloysite nanotubes through copolymerization of acrylic monomers, thereby grafting pentafluorophenyl groups and dodecyl groups containing fluorine and benzene rings onto the surface of the halloysite nanotubes. Both groups have relatively high hydrophobicity and stability, but the long-chain alkyl structure in the dodecyl group strengthens the intermolecular hydrophobic interaction, thereby reducing the thermal conductivity. Therefore, by blending dodecyl methacrylate and pentafluorophenyl methacrylate and carrying out copolymerization to modify the halloysite nanotubes, corresponding functional groups can be grafted onto their surfaces, thereby producing copolymer-modified halloysite nanotubes.

[0022] By adopting the above technical solution, copolymer-modified halloysite nanotubes are added to the hydrolyzed silica sol, and the copolymer-modified halloysite nanotubes and silica gel are bonded through Si-O-Si bonds during the basic catalytic process. At the same time, the hydroxyl groups on the surface of the silica gel, the hydroxyl groups on the surface of the modified halloysite nanotubes, and the isocyanate groups of diphenylmethane diisocyanate are crosslinked and hardened to form a three-dimensional network structure, which can promote the uniform distribution of the copolymer-modified halloysite nanotubes in the silica aerogel and further improve the mechanical properties, weather resistance, and hydrophobicity of the formed composite aerogel. Furthermore, during the crosslinking and curing process of diphenylmethane diisocyanate, water acts as a blowing agent, imparting high porosity and a large specific surface area to the composite aerogel produced. Furthermore, diphenylmethane diisocyanate is a curing agent containing a polybenzene ring, and the hydrophobicity of the benzene ring makes the composite aerogel relatively highly hydrophobic. The hydrophobicity of the composite aerogel after hydrophobic modification is further improved, thereby imparting excellent water repellency and a relatively large contact angle to the final modified silica aerogel powder.

[0023] By introducing halloysite nanotubes into silica aerogel matrix materials, the water-repellent effect of the material can be significantly improved by transferring hydrophobic groups to the surface of the halloysite nanotubes, which have a relatively high specific surface area. Furthermore, the halloysite nanotubes have a nano-sized tubular structure with a relatively large aspect ratio, so the modified silica aerogel powder produced has good mechanical properties and temperature resistance.

[0024] According to a second aspect, the present application provides a modified silica aerogel powder produced by the above-mentioned method for producing a modified silica aerogel powder.

[0025] According to a third aspect, the present application provides an aerogel slurry made from the above modified silica aerogel powder, wherein the aerogel slurry comprises the following parts by weight of raw materials: 15-45 parts modified silica aerogel powder, 35-60 parts lightweight microspheres, 250-350 parts aqueous inorganic resin, 5-10 parts sodium bentonite, 4-10 parts wetting agent, 4-8 parts dispersant, 2-3 parts antifoaming agent, 2-3 parts antibacterial agent, and 400-550 parts water.

[0026] Optionally, the lightweight microspheres include one or more of hollow glass microspheres, hollow silica microspheres, hollow ceramic microspheres, and hollow phenolic resin microspheres, and the particle size of the lightweight microspheres is 100 to 350 μm, and the density of the lightweight microspheres is 0.1 to 0.4 g / cm. 3 is.

[0027] By adopting the above technical solution, the silicate in the aqueous inorganic resin has relatively high permeability and can undergo a mineralization reaction with the calcium ions in the lightweight microspheres and carbon dioxide in the air to form a membrane. The silicate in the aqueous inorganic resin can undergo a mineralization reaction with the aluminum ions in the aluminum oxygen layer in the halloysite nanotubes to form a membrane, thereby improving the membrane-forming effect of the aerogel slurry on the surface of the fiber felt and reducing the cracking and collapse of the aerogel slurry during drying, thereby reducing the occurrence of powder and slag shedding, and ensuring that the produced aerogel insulation felt has excellent insulation properties.

[0028] Sodium bentonite can provide an appropriate viscosity for the application of the aerogel slurry, which is beneficial for the spreading and penetration of the aerogel slurry on the surface of the fiber felt. Secondly, sodium bentonite has a relatively good thickening effect on organic resins, which can improve the sand-down resistance of the aerogel slurry, thereby improving the uniformity of the application of the aerogel slurry, reducing the cracking and collapse of the aerogel slurry after drying, and reducing the occurrence of powder shedding.

[0029] By adopting the above technical solution, the aerogel slurry is an aqueous slurry, and when the aerogel slurry is applied to the surface of the hydrophilic fiber felt, it forms an aqueous film with excellent adhesion and leveling on the surface of the hydrophilic fiber felt, making the application of the aerogel slurry more uniform and stable and less likely to drip. In the subsequent baking process, high-temperature treatment at 300-500°C can quickly evaporate the water molecules in the coating layer, which is beneficial to maintaining the overall structure of the coating layer. The coating layer can completely cover the surface of the fiber felt, thereby further improving the insulation capacity and reducing the powder shedding rate of the aerogel insulation felt. Meanwhile, the modified silica aerogel powder on the surface of the coating layer is exposed, and due to the various hydrophobic groups carried on its surface, the final aerogel insulation felt has excellent water repellency and a relatively large contact angle, which results in low thermal conductivity and effective heat insulation.

[0030] According to a fourth aspect, the present application provides a method for producing the above-mentioned aerogel slurry, The process includes adding water, a dispersant, an antifoaming agent, and half of the wetting agent to a reaction vessel, stirring, adjusting the pH to 9-9.5, adding aqueous inorganic resin and modified silica aerogel powder, controlling the temperature to 45-50°C, stirring, adding lightweight microspheres and sodium bentonite, stirring, adding an antibacterial agent and the remaining wetting agent, stirring, and producing an aerogel slurry.

[0031] According to a fifth aspect, the present application provides an application of the above aerogel slurry in the manufacture of an aerogel insulating felt.

[0032] Optionally, the method for manufacturing the aerogel insulating felt includes the steps of applying an aerogel slurry to the surface of a fiber felt, leaving the fiber felt to stably adsorb the aerogel slurry, and drying the aerogel insulating felt.

[0033] Optionally, the fiber felt is one selected from glass fiber felt, carbon fiber felt, nickel fiber felt, stainless steel fiber felt, aluminum silicate fiber felt, ceramic fiber felt, alumina fiber felt, basalt fiber felt and polyacrylonitrile fiber felt.

[0034] Optionally, the thickness of the fiber felt is 0.5 to 500 mm.

[0035] Optionally, the method for producing the aerogel insulating felt includes: Step (1) of applying the aerogel slurry to the surface of the fiber felt, leaving it to stand to allow the aerogel slurry to be stably adsorbed on the fiber felt, and then drying it. During the drying process, the aerogel slurry is first kept at 100-150°C for 1-2 hours, and then kept at 300-500°C for 1-2 hours to produce a pre-treated aerogel insulating felt. Step (2) is also included. The pre-treated aerogel insulating felt produced in step (1) is set up, and a hydrophobic modifier is sprayed from top to bottom using a spray gun, and dried at 200°C. Then, the spraying is repeated once, and the aerogel insulating felt is dried again to produce the aerogel insulating felt.

[0036] Optionally, the hydrophobic modifier is trimethylchlorosilane.

[0037] Optionally, the adsorption amount of the aerogel slurry on the surface of the fiber felt is 0.5 to 500 kg / m 2 is. [Effects of the Invention]

[0038] From the above, the present invention includes at least one of the following beneficial technical effects. 1. In this application, copolymer-modified halloysite nanotubes are added to hydrolyzed silica sol to prepare a composite aerogel. Through crosslinking with diphenylmethane diisocyanate, a composite aerogel with a three-dimensional network structure, high porosity, and high specific surface area is obtained, with hydrophobic groups such as pentafluorophenyl groups grafted onto the surface. The modified silica aerogel powder produced based on this method exhibits relatively strong water repellency. This application also produces an aerogel slurry from the modified silica aerogel powder, which is then applied to the surface of a fiber felt to produce an aerogel insulating felt. The aerogel insulating felt produced in this application has low thermal conductivity and can effectively block heat transfer. The aerogel insulating felt produced in this application has excellent temperature resistance and good mechanical properties, making it suitable for a variety of insulation applications. 2. The modified silica aerogel powder, aerogel slurry and aerogel insulating felt prepared in this application have low raw material costs, simple manufacturing processes and easy operation, and relatively low production costs, which are advantageous for industrial production and application and have important practical significance for the development of related industries. DETAILED DESCRIPTION OF THE INVENTION

[0039] The present application provides a method for producing a modified silica aerogel powder, Step S1: adding dodecyl methacrylate, pentafluorophenyl methacrylate, an organic solvent and halloysite nanotubes into a reaction vessel, adding an initiator, controlling the reaction temperature at 70-80°C, reacting for 4-8 hours with stirring, cooling, filtering to remove the filtration residue, washing, and drying to prepare copolymer-modified halloysite nanotubes for use; Step S2: mixing and stirring a silicon source, deionized water, absolute ethanol, and n-hexane at room temperature to prepare a silicon source precursor solution; Step S3 of adding an acid catalyst to the silicon source precursor solution prepared in step S2, adjusting the pH of the solution to 2 to 3, and carrying out a hydrolysis reaction under heating in a water bath to prepare a silica sol; Step S4: adding a basic catalyst to the silica sol prepared in step S3, adjusting the pH of the solution to 6-7, adding the copolymer-modified halloysite nanotubes prepared in step S1, stirring and ultrasonicating, adding diphenylmethane diisocyanate and an organotin catalyst, reacting at 50-60°C for 8-15 hours, and then leaving to stand to prepare a wet gel. Step S5 includes aging the wet gel produced in step S4, controlling the aging time to 10-15 hours, adding a hydrophobic modifier to perform hydrophobic modification, drying, and ball milling to produce modified silica aerogel powder.

[0040] The present application provides a modified silica aerogel powder produced by the above production method.

[0041] The present application provides an aerogel slurry, which comprises the following parts by weight of raw materials: 15-45 parts modified silica aerogel powder, 35-60 parts lightweight microspheres, 250-350 parts aqueous inorganic resin, 5-10 parts sodium bentonite, 4-10 parts wetting agent, 4-8 parts dispersant, 2-3 parts defoaming agent, 2-3 parts antibacterial agent, and 400-550 parts water.

[0042] The aerogel slurry of the present application is produced by the following method: The process includes adding water, a dispersant, an antifoaming agent, and half of the wetting agent to a reaction vessel, stirring, adjusting the pH to 9-9.5, adding aqueous inorganic resin and modified silica aerogel powder, controlling the temperature to 45-50°C, stirring, adding lightweight microspheres and sodium bentonite, stirring, adding an antibacterial agent and the remaining wetting agent, stirring, and producing an aerogel slurry.

[0043] The aerogel slurry of the present application can be applied in the field of manufacturing aerogel insulating felt.

[0044] The manufacturing method of aerogel insulation felt is as follows: The method includes the steps of applying the aerogel slurry to the surface of a fiber felt, leaving it to stand to allow the aerogel slurry to be stably adsorbed onto the fiber felt, and then drying the same to produce an aerogel insulating felt.

[0045] The technical problem solved by this application is that composite insulation felts produced by conventional slurry molding methods have relatively high thermal conductivity, low mechanical strength, and inability to withstand high temperatures. The modified silica aerogel produced by this application has a three-dimensional network cross-linked structure, high porosity, and high specific surface area, and is grafted with hydrophobic groups such as pentafluorophenyl groups on its surface. The modified silica aerogel powder produced based on this has relatively strong water-repellent properties. This application also produces an aerogel slurry from the modified silica aerogel powder and applies the aerogel slurry to the surface of a fiber felt to produce an aerogel insulation felt. The aerogel insulation felt produced by this application has low thermal conductivity and can effectively block heat transfer. The aerogel insulation felt produced by this application has excellent temperature resistance and good mechanical properties, making it suitable for various insulation applications.

[0046] The present application will now be described in more detail with reference to specific examples.

[0047] (Production Example 1) The method for producing the modified silica aerogel powder in Production Example 1 is as follows: Step S1: add 0.6 kg of dodecyl methacrylate, 0.25 kg of pentafluorophenyl methacrylate, 25 kg of organic solvent and 6 kg of halloysite nanotubes into a reaction vessel, add 0.03 kg of initiator, control the reaction temperature at 80°C, react for 6 hours while stirring, cool, filter to take out the filtration residue, wash and dry to prepare copolymer-modified halloysite nanotubes for use; Step S2: Stirring and mixing 1 kg of silicon source, 7 kg of deionized water, 5 kg of absolute ethanol, and 1.8 kg of n-hexane at room temperature to prepare a silicon source precursor solution; Step S3: adding an acid catalyst to the silicon source precursor solution until the pH becomes 2 to 3, carrying out a hydrolysis reaction under heating in a water bath, and reacting for 5 hours, the water bath temperature is 70°C, and producing a silica sol; Step S4: take 26 kg of silica sol, add a basic catalyst to adjust the pH to 6-7, then add 2 kg of copolymer-modified halloysite nanotubes, stir for 30 minutes, ultrasonicate for 10 minutes, add 0.6 kg of diphenylmethane diisocyanate and 0.05 kg of organotin catalyst, react at 60°C for 12 hours, and stand for 3 hours to produce a wet gel; and step S5, placing the prepared wet gel in a 1:4 volume ratio water / absolute ethanol mixture, and aging it at 25°C and 1 atmospheric pressure for 12 hours at a constant temperature and pressure. The aged wet gel is then immersed in a hydrophobic modifier for hydrophobic modification for 24 hours, and then freeze-dried at -50°C under a vacuum of 100 Pa for 24 hours. The dried modified silica aerogel is ball-milled until the particle size reaches 800 mesh, thereby preparing modified silica aerogel powder.

[0048] The halloysite nanotubes used in Production Example 1 were coupling-modified halloysite nanotubes, and the production process of the coupling-modified halloysite nanotubes was as follows: Step (1): 6 kg of halloysite nanotubes are mixed with 60 kg of 20 wt% urea solution, ultrasonicated for 30 minutes, allowed to stand for 10 hours, and then 30 kg of 5 wt% sulfuric acid solution is added, allowed to stand for 3 hours, filtered, and dried to produce pre-treated halloysite nanotubes; and (2) adding 0.6 kg of a silane coupling agent, 50 kg of water and 5 kg of pre-treated halloysite nanotubes to a reaction vessel, adjusting the pH to 9-10, reacting at 80°C for 2 hours, adjusting the pH to neutral, cooling, filtering, washing and drying the filtration residue to produce coupling-modified halloysite nanotubes.

[0049] The silane coupling agent used in Production Example 1 was KH-570.

[0050] The dodecyl methacrylate used in Production Example 1 was purchased from Sigma-Aldrich and has a CAS number of 142-90-5.

[0051] The pentafluorophenyl methacrylate used in Production Example 1 was purchased from TIXIA (Shanghai) Chemical Industry Development Co., Ltd., and has the product number P2289 and the CAS number 13642-97-2.

[0052] The silicon source used in Production Example 1 was tetraethyl orthosilicate.

[0053] The acid catalyst used in Production Example 1 was an oxalic acid solution, and the concentration of oxalic acid in the oxalic acid solution was 0.4 wt %, and the basic catalyst used in Production Example 1 was an aqueous ammonia solution, and the concentration of ammonia water in the aqueous ammonia solution was 0.4 wt %.

[0054] The organotin catalyst used in Production Example 1 was dibutyltin dilaurate.

[0055] The hydrophobic modifier in Production Example 1 consists of n-hexane and trimethylchlorosilane in a weight ratio of 8:1.

[0056] (Production Example 2) The method for producing the modified silica aerogel powder in Production Example 2 is as follows: Step S1: add 0.5 kg of dodecyl methacrylate, 0.3 kg of pentafluorophenyl methacrylate, 25 kg of organic solvent and 6 kg of halloysite nanotubes into a reaction vessel, add 0.03 kg of initiator, control the reaction temperature at 80°C, react for 6 hours while stirring, cool, filter to take out the filtration residue, wash and dry to prepare modified halloysite nanotubes for use; Step S2: Stirring and mixing 1 kg of silicon source, 7 kg of deionized water, 5 kg of absolute ethanol, and 1.8 kg of n-hexane at room temperature to prepare a silicon source precursor solution; Step S3: adding an acid catalyst to the silicon source precursor solution to adjust the solution pH to 2-3, and carrying out a hydrolysis reaction under heating in a water bath for 5 hours, the water bath temperature is 70°C, and a silica sol is produced; Step S4: take 26 kg of silica sol, add a basic catalyst to adjust the solution pH to 6-7, add 1 kg of copolymer-modified halloysite nanotubes, stir for 30 minutes, ultrasonicate for 10 minutes, add 0.5 kg of diphenylmethane diisocyanate and 0.05 kg of organotin catalyst, react at 60°C for 12 hours, and then stand for 3 hours to prepare a wet gel; and step S5, placing the prepared wet gel in a 1:4 volume ratio water / absolute ethanol mixture, and aging it at 25°C and 1 atmospheric pressure for 12 hours at a constant temperature and pressure. The aged wet gel is then immersed in a hydrophobic modifier for hydrophobic modification for 24 hours, and then freeze-dried at -50°C under a vacuum of 100 Pa for 24 hours. The dried modified silica aerogel is ball-milled until the particle size reaches 800 mesh, thereby preparing modified silica aerogel powder.

[0057] The halloysite nanotubes used in Production Example 2 were coupling-modified halloysite nanotubes, and the production process was the same as in Production Example 1.

[0058] The silicon source used in Production Example 2 was methyltrimethoxysilane, with a CAS number of 1185-55-3.

[0059] The acid catalyst, basic catalyst and organotin catalyst used in Production Example 2 were the same as those in Production Example 1.

[0060] The hydrophobic modifier in Preparation Example 2 consists of n-hexane and trimethylchlorosilane in a weight ratio of 12:1.

[0061] (Production Example 3) The method for producing the modified silica aerogel powder in Production Example 3 is as follows: Step S1: Add 1 kg of dodecyl methacrylate, 0.2 kg of pentafluorophenyl methacrylate, 25 kg of organic solvent and 6 kg of halloysite nanotubes into a reaction vessel, add 0.03 kg of initiator, control the reaction temperature at 80°C, react for 6 hours while stirring, cool, filter to take out the filtration residue, wash and dry to prepare copolymer-modified halloysite nanotubes for use; Step S2: Stirring and mixing 1 kg of silicon source, 7 kg of deionized water, 5 kg of absolute ethanol, and 1.8 kg of n-hexane at room temperature to prepare a silicon source precursor solution; Step S3: adding an acid catalyst to the silicon source precursor solution until the pH becomes 2 to 3, carrying out a hydrolysis reaction under heating in a water bath, and reacting for 5 hours, the water bath temperature is 70°C, and producing a silica sol; Step S4: take 26 kg of silica sol, add a basic catalyst to adjust the pH to 6-7, then add 3 kg of copolymer-modified halloysite nanotubes, stir for 30 minutes, ultrasonicate for 10 minutes, add 1 kg of diphenylmethane diisocyanate and 0.05 kg of organotin catalyst, react at 60°C for 12 hours, and stand for 3 hours to produce a wet gel; Step S5 includes placing the prepared wet gel in a water / absolute ethanol mixture with a volume ratio of 1:4, and aging it at 25°C and 1 atmospheric pressure for 12 hours at a constant temperature and pressure; immersing the aged wet gel in a hydrophobic modifier for hydrophobic modification for 24 hours; and then freeze-drying the aged wet gel at a temperature of -50°C, a vacuum of 100 Pa, and a drying time of 24 hours; and ball-milling the dried modified silica aerogel until the particle size is 800 mesh to prepare modified silica aerogel powder.

[0062] The halloysite nanotubes used in Production Example 3 were coupling-modified halloysite nanotubes, and the production process was basically the same as in Production Example 1, except that the silane coupling agent used was KH-550.

[0063] The silicon source used in Production Example 3 was sodium silicate.

[0064] The acid catalyst, base catalyst and organotin catalyst used in Production Example 3 were the same as those in Production Example 1.

[0065] The hydrophobic modifier in Preparation Example 3 consists of n-hexane and trimethylchlorosilane in a weight ratio of 7:1.

[0066] (Production Example 4) Preparation Example 4 is based on Preparation Example 1, except that the coupling-modified halloysite nanotubes used in step S2 of Preparation Example 4 did not undergo the pretreatment process of urea solution and sulfuric acid solution before reacting with the coupling agent.

[0067] (Comparative Manufacturing Example 1) Comparative Production Example 1 is based on Comparative Production Example 1, except that in step S1, pentafluorophenyl methacrylate is replaced with the same amount of tetrafluoroethyl methacrylate.

[0068] In the comparative manufacturing example 1, step S1 is 0.6 kg of dodecyl methacrylate, 0.25 kg of tetrafluoroethyl methacrylate, 25 kg of organic solvent and 6 kg of halloysite nanotubes are added to a reaction vessel, 0.03 kg of initiator is added, the reaction temperature is controlled at 80°C, and the reaction is carried out with stirring for 6 hours. The mixture is then cooled, filtered to remove the residue, washed and dried, and copolymer-modified halloysite nanotubes are produced and ready for use in step S1.

[0069] (Comparative Manufacturing Example 2) Comparative Production Example 2 is based on Comparative Production Example 1, except that in Comparative Production Example 2, the halloysite nanotubes are not modified with pentafluorophenyl methacrylate in step S1.

[0070] In the comparative manufacturing example 2, step S1 is 0.6 kg of dodecyl methacrylate, 25 kg of organic solvent and 6 kg of halloysite nanotubes are added to a reaction vessel, 0.03 kg of initiator is added, the reaction temperature is controlled at 80°C, and the reaction is carried out with stirring for 6 hours. The mixture is then cooled, filtered to remove the filtration residue, washed and dried to produce copolymer-modified halloysite nanotubes, which are ready for use in step S1.

[0071] (Comparative Manufacturing Example 3) Comparative Preparation 3 is based on Example 1, except that in step S1, dodecyl methacrylate is replaced with the same amount of n-butyl methacrylate.

[0072] In the comparative manufacturing example 3, step S1 is 0.6 kg of n-butyl methacrylate, 0.25 kg of pentafluorophenyl methacrylate, 25 kg of organic solvent and 6 kg of halloysite nanotubes are added to a reaction vessel, 0.03 kg of initiator is added, the reaction temperature is controlled at 80°C, and the reaction is carried out with stirring for 6 hours. The mixture is then cooled, filtered to remove the residue, washed and dried, to produce copolymer-modified halloysite nanotubes, which are ready for use in step S1.

[0073] (Comparative Manufacturing Example 4) Comparative Production Example 4 is based on Example 1, except that in Comparative Production Example 4, the halloysite nanotubes are not modified with dodecyl methacrylate in step S1.

[0074] In the comparative manufacturing example 4, step S1 is Add 0.25 kg of pentafluorophenyl methacrylate, 25 kg of organic solvent and 6 kg of halloysite nanotubes to a reaction vessel, add 0.03 kg of initiator, control the reaction temperature to 80°C, react for 6 hours with stirring, cool, filter to remove the filtration residue, wash and dry to produce copolymer-modified halloysite nanotubes, which are ready for use in step S1.

[0075] (Examples 1 to 3) Examples 1 to 3 are different aerogel slurries that were produced, and differ in the amount of raw material blended, specifically as follows:

[0076] The aerogel slurry produced in Example 1 was made from the following parts by weight of ingredients: Contains 38 parts modified silica aerogel powder, 45 parts lightweight microspheres, 280 parts aqueous inorganic resin, 8 parts sodium bentonite, 6 parts wetting agent, 6 parts dispersing agent, 2.5 parts defoamer, 2.5 parts antibacterial agent, and 500 parts water.

[0077] The aerogel slurry produced in Example 2 was prepared from the following ingredients in parts by weight: Contains 15 parts modified silica aerogel powder, 60 parts lightweight microspheres, 250 parts aqueous inorganic resin, 5 parts sodium bentonite, 10 parts wetting agent, 4 parts dispersant, 2 parts defoamer, 2 parts antibacterial agent, and 400 parts water.

[0078] The aerogel slurry produced in Example 3 was made from the following parts by weight of ingredients: Contains 45 parts modified silica aerogel powder, 35 parts lightweight microspheres, 350 parts aqueous inorganic resin, 10 parts sodium bentonite, 4 parts wetting agent, 8 parts dispersant, 3 parts defoamer, 3 parts antibacterial agent, and 550 parts water.

[0079] The modified silica aerogel powders used in Examples 1 to 3 were all produced in Production Example 1.

[0080] The lightweight microspheres used in Examples 1 to 3 were hollow ceramic microspheres with an average particle size of 150 μm and an average density of 0.3 g / cm 3 is.

[0081] The aqueous inorganic resin used in Examples 1 to 3 was a lithium silicate resin purchased from Tianjin Advanced Materials Co., Ltd., with a module (silicate-alkali ratio) of 4.8±0.1, an SiO2 content of 19.0 to 21.0 wt%, and a Li2O content of 2.0 to 2.2 wt%.

[0082] The wetting agent used in Examples 1 to 3 was METOLAT (registered trademark) 514 manufactured by Munzing Chemicals, Germany.

[0083] The dispersant used in Examples 1 to 3 was EDAPLAN 490 manufactured by Munzing Chemicals of Germany.

[0084] The antifoaming agent used in Examples 1 to 3 was AGITAN (registered trademark) 299 manufactured by Munzing Chemicals, Germany.

[0085] The antibacterial agent used in Examples 1 to 3 was No. 75 industrial antifungal agent oxobifenoxine.

[0086] The manufacturing process of Examples 1 to 3 is as follows: The process includes adding water, dispersant, antifoaming agent, and half of the wetting agent to a reaction vessel, stirring for 5 minutes, adjusting the pH to 9-9.5, adding aqueous inorganic resin and modified silica aerogel powder, controlling the temperature to 45°C, stirring for 30 minutes, adding lightweight microspheres and sodium bentonite, stirring for 5 minutes, adding the antibacterial agent and the remaining wetting agent, and stirring for 5 minutes to produce an aerogel slurry.

[0087] Examples 4-5 Example 4 is based on Example 1, except that the amount of modified silica aerogel powder used in Example 4 is changed from 38 parts to 15 parts.

[0088] Example 5 is based on Example 1, except that the amount of modified silica aerogel powder used in Example 5 is changed from 38 parts to 45 parts.

[0089] (Examples 6 to 8 and Comparative Examples 1 and 2) Examples 6 to 8 and Comparative Examples 1 to 2 are based on Example 1, except that the modified silica aerogel powders used in Examples 6 to 8 and Comparative Examples 1 to 2 are different; see Table 1 for details.

[0090] [Table 1]

[0091] (Comparative Example 5) Comparative Example 5 is based on Example 1, except that in Comparative Example 5 the modified silica aerogel powder in the raw materials was replaced with a commercially available silica aerogel powder, Wacker H15 type fumed silica from Germany.

[0092] (Application Examples 1 to 8) Application Examples 1 to 8 are aerogel heat insulating felts produced using the aerogel slurries produced in Examples 1 to 8, respectively, and the aerogel slurries used in Application Examples 1 to 8 correspond to Examples 1 to 8 in order.

[0093] The manufacturing method of the aerogel insulating felt in Application Examples 1 to 8 is as follows: The aerogel slurry was used to scrape a 5 mm thick glass fiber felt, which was then left to stand to allow the aerogel slurry to stably adsorb onto the fiber felt. The felt was then dried and heated at 150°C for 1 hour, then at 200°C for 2 hours to produce an aerogel insulating felt. The adsorption of the aerogel slurry on the fiber felt surface was 4 kg / m. 2 The method includes a step of controlling the

[0094] The density of the glass fiber felt used in Examples 1 to 8 is 0.2 g cm -3 is.

[0095] (Application example 9) Application Example 9 is a manufacturing method of Application Example 9, The aerogel slurry was used to scrape a 5 mm thick glass fiber felt, which was then left to stand and dry to ensure stable adsorption of the aerogel slurry onto the fiber felt. The felt was then first heated at 150°C for 1 hour and then at 200°C for 2 hours to produce a pre-treated aerogel insulating felt. The adsorption amount of the aerogel slurry on the fiber felt surface was 4 kg / m. 2 Step (1) of controlling The pre-treated aerogel insulating felt produced in step (1) is then stood up, and a hydrophobic modifier is sprayed from top to bottom using a spray gun, dried at 200°C, and then sprayed once more and dried again to produce an aerogel insulating felt. The hydrophobic modifier used is trimethylchlorosilane, and the spray amount per spray is 40g / m. 2 This is based on Application Example 1, except that it includes step (2) where:

[0096] (Application comparison example 1) Comparative Application Example 1 is based on Comparative Application Example 1, except that the aerogel slurry in Comparative Application Example 1 is the aerogel slurry produced in Comparative Application Example 1.

[0097] (Application Comparison Example 2) Comparative Application Example 2 is based on Application Example 1, except that the aerogel slurry in Comparative Application Example 2 is the aerogel slurry produced in Comparative Application Example 2.

[0098] (Application Comparison Example 3) Comparative Application Example 3 is based on Application Example 1, except that the aerogel slurry in Comparative Application Example 3 is the aerogel slurry produced in Comparative Application Example 3.

[0099] (Application Comparison Example 4) Comparative Application Example 4 is based on Application Example 1, except that the aerogel slurry in Comparative Application Example 4 is the aerogel slurry produced in Comparative Application Example 4.

[0100] (Application Comparison Example 5) Comparative Application Example 5 is based on Application Example 1, except that the aerogel slurry in Comparative Application Example 5 is the aerogel slurry produced in Comparative Application Example 5.

[0101] Performance Detection 1. The thermal conductivity (W / (m·K)) at 25°C of the aerogel insulating felts manufactured in Application Examples 1 to 9 and Application Comparison Examples 1 to 5 was measured in accordance with the standard GB / T 10295-2008 "Determination of Steady-State Thermal Resistance and Related Properties of Thermal Insulation Materials Using a Heat Flow Meter." The measurement results are shown in Table 2. 2. The compressive strength (MPa) of the aerogel heat insulating felts produced in Application Examples 1 to 9 and Application Comparative Examples 1 to 5 was measured, and the measurement results are shown in Table 2. 3. Referring to the standard GB 34336-2017 "Standard for Nano Aerogel Composite Insulation Articles," the powder shedding rate (%) of the aerogel insulation felts manufactured in Application Examples 1 to 9 and Application Comparison Examples 1 to 5 was measured, and the measurement results are shown in Table 2. 4. Aerogel insulation felt quench resistance test: Using a NexGen oil burner, at temperatures of 1009 to 1036°C, two aerogel insulation felt samples were used for each application example. The thickness was controlled to 10 mm, and the same side of the sample was baked for 30 minutes. After baking, the presence or absence of quenching was observed. The maximum heat flow rate (W / cm) from the back to the front 305 mm of the two aerogel insulation felt samples was measured. 2 The heat generation time (s) and the heat generation time (s) were measured, and a hardening resistance test was carried out for Application Examples 3, 5, and 9, respectively. The measurement results are shown in Table 3. (The evaluation criteria were that the maximum heat flow rate from the back surface of the heat insulating felt to the surface of 305 mm was 2.27 W / cm.) 2 (must not exceed

[0102] [Table 2]

[0103] [Table 3]

[0104] Analysis of the data in Table 2 reveals that the aerogel insulation felt produced in this application has a low thermal conductivity of 0.014 W / (m·K) at 25°C, demonstrating its extremely low thermal conductivity and effective heat insulation. Comparing Application Example 1 with Application Comparative Examples 1 and 2, it is clear that the aerogel insulation felt produced using tetrafluoroethyl methacrylate instead of pentafluorophenyl methacrylate has a significantly higher thermal conductivity, significantly weaker insulating ability, and a significantly higher powder shedding rate. Pentafluorophenyl methacrylate significantly controls the hydrophobicity of the modified silica aerogel powder and aerogel insulation felt, further improving the insulating ability of the aerogel insulation felt and facilitating the rapid removal of moisture from the aerogel insulation felt coating during firing, thereby maintaining the structural integrity of the aerogel insulation felt coating and reducing the occurrence of powder shedding. Comparing Application Example 1 with Application Comparison Examples 3 and 4, it can be seen that the use of long-chain alkyl methacrylate improves the hydrophobicity of the modified silica aerogel powder to some extent, but the effect of improving the hydrophobicity of the modified silica aerogel powder is lower than that of pentafluorophenyl methacrylate.

[0105] Analysis of the data in Table 3 reveals that the aerogel insulation felt produced in this application has excellent heat resistance, insulation properties, and fire resistance, and can be used in a variety of fire protection facilities, insulation facilities, and fire protection scenarios. In addition, the aerogel insulation felt produced in this application has high mechanical strength and little powder shedding, making it suitable for a variety of insulation scenarios.

[0106] The above are all preferred embodiments of the present application, and do not limit the scope of protection of the present application, so that any equivalent modifications made according to the structure, shape, and principle of the present application should be included within the scope of protection of the present application.

Claims

1. A method for producing a modified silica aerogel powder, comprising: Step S1: adding dodecyl methacrylate, pentafluorophenyl methacrylate, an organic solvent and halloysite nanotubes into a reaction vessel, adding an initiator, controlling the reaction temperature at 70-80°C, reacting for 4-8 hours with stirring, cooling, filtering to remove the filtration residue, washing, and drying to prepare a copolymer-modified halloysite nanotube for use; Step S2: mixing and stirring a silicon source, deionized water, absolute ethanol, and n-hexane at room temperature to prepare a silicon source precursor solution; Step S3: adding an acid catalyst to the silicon source precursor solution prepared in step S2, adjusting the pH of the solution to 2 to 3, and carrying out a hydrolysis reaction under heating in a water bath to prepare a silica sol; Step S4: adding a basic catalyst to the silica sol prepared in step S3, adjusting the pH of the solution to 6-7, adding the copolymer-modified halloysite nanotubes prepared in step S1, stirring and ultrasonicating, adding diphenylmethane diisocyanate and an organotin catalyst, reacting at 50-60°C for 8-15 hours, and then leaving to stand to prepare a wet gel. and step S5 of aging the wet gel produced in step S4, controlling the aging time to 10 to 15 hours, adding a hydrophobic modifier to hydrophobize the wet gel, drying, and ball milling to produce a modified silica aerogel powder.

2. 2. The method for producing modified silica aerogel powder according to claim 1, wherein in step S1, the halloysite nanotubes are coupling-modified halloysite nanotubes, and the preparation process of the coupling-modified halloysite nanotubes includes the steps of: mixing the halloysite nanotubes with a urea solution, ultrasonicating, and allowing to stand; then adding sulfuric acid, allowing to stand, filtering, and drying to prepare pre-treated halloysite nanotubes; and adding a silane coupling agent, water, and the pre-treated halloysite nanotubes to a reaction vessel, adjusting the pH to 9-10, reacting at 60-80°C for 2-3 hours, adjusting the pH to neutral, cooling, filtering, washing the filtration residue, and drying to prepare the coupling-modified halloysite nanotubes.

3. 2. The method for producing a modified silica aerogel powder according to claim 1, wherein in step S3, the acid catalyst is one of oxalic acid solution, hydrochloric acid solution, phosphoric acid solution, and citric acid solution, and the concentration is 0.3-0.5 wt %; and in step S4, the basic catalyst is one of ammonia water solution, sodium carbonate solution, and sodium bicarbonate solution, and the concentration is 0.2-0.4 wt %.

4. 2. The method for producing a modified silica aerogel powder according to claim 1, wherein in step S5, the hydrophobic modifier is trimethylchlorosilane.

5. Use of a modified silica aerogel powder produced by the method for producing a modified silica aerogel powder according to any one of claims 1 to 4 in producing an aerogel slurry, The aerogel slurry comprises, by weight, 15-45 parts of the modified silica aerogel powder, 35-60 parts of lightweight microspheres, 250-350 parts of aqueous inorganic resin, 5-10 parts of sodium bentonite, 4-10 parts of wetting agent, 4-8 parts of dispersant, 2-3 parts of antifoaming agent, 2-3 parts of antibacterial agent, and 400-550 parts of water.

6. 6. The method for producing aerogel slurry according to claim 5, comprising the steps of: adding water, a dispersant, an antifoaming agent, and half of the wetting agent into a reaction vessel, stirring, adjusting the pH to 9-9.5, adding aqueous inorganic resin and modified silica aerogel powder, controlling the temperature to 45-50°C, stirring, adding lightweight microspheres, stirring, adding an antibacterial agent and the remaining wetting agent, stirring, to produce an aerogel slurry.

7. 10. Use of an aerogel slurry produced by the method for producing an aerogel slurry according to claim 6 in the production of an aerogel insulating felt.

8. The method for producing the aerogel insulating felt includes the steps of applying the aerogel slurry to a surface of a fiber felt, leaving the fiber felt to stand to stably adsorb the aerogel slurry, and drying the fiber felt to produce the aerogel insulating felt; the fiber felt is one selected from glass fiber felt, carbon fiber felt, nickel fiber felt, stainless steel fiber felt, aluminum silicate fiber felt, ceramic fiber felt, alumina fiber felt, basalt fiber felt, and polyacrylonitrile fiber felt, and the thickness of the fiber felt is 0.5 to 500 mm; The use according to claim 7, characterized in that the adsorption amount of the aerogel slurry on the surface of the fiber felt is 0.5 to 50 kg / m2.

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