Aerogel-based weather-resistant thermal insulation felt and preparation method thereof

Abstract

The invention discloses an aerogel-based weather-resistant thermal insulation felt and a preparation method thereof, belongs to the technical field of thermal insulation felt processing, and is used for solving the technical problem that the thermal insulation performance and the weather resistance of a thermal insulation felt in the prior art need to be further improved. The modified aerogel base solution and the mixed slurry are added, ammonia water is added to adjust the pH value to be 8 + / -0.5, the mixture is transferred into a drying box with the temperature being 40-50 DEG C, a heat preservation reaction is conducted for 0.5-1 h, a dimethyldiethoxysilane solution is added, a heat preservation reaction is conducted for 8-10 h, n-hexane elution and drying are conducted, and the heat insulation felt is obtained. The modified aerogel and the glass fiber felt are used as base materials, the heat insulation felt is prepared through an impregnation method, the heat preservation performance and the weather resistance of the heat insulation felt are improved, and the mechanical performance of the heat insulation felt is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal insulation felt processing, and particularly relates to an aerogel-based weather-resistant thermal insulation felt and a preparation method thereof. Background Art

[0002] As an important direction for the development of clean energy, the system efficiency of solar energy utilization technology is closely related to the thermal management performance. In a solar thermal conversion system, the thermal insulation material undertakes the key function of thermal energy blocking, and its performance directly affects the control of heat loss and the energy conversion efficiency of the collector.

[0003] In the long-term outdoor application of traditional solar thermal insulation materials, they face severe challenges in environmental adaptability. The commonly used thermal insulation materials in current solar systems mainly include conventional thermal insulation products such as mineral wool and foam plastics. Among them, aerogel materials have excellent thermal insulation potential due to their unique nano-porous structure, but there are still technical bottlenecks in solar application scenarios.

[0004] In the prior art, unmodified aerogel materials have insufficient mechanical strength and are difficult to withstand the vibration load during the operation of the solar system. When adding fiber materials to improve the mechanical properties of the thermal insulation felt, due to the poor bonding force between the aerogel and the fiber, it is often difficult to achieve the expected improvement in the mechanical properties of the thermal insulation felt. Moreover, aerogels have a high water absorption rate in a humid environment, which not only increases the self-weight load but also significantly reduces the thermal insulation effect. They are prone to aging and decomposition under long-term ultraviolet irradiation, shortening the service life. To improve the bonding force between the fiber and the aerogel, an organic binder is added. However, under high-temperature working conditions, the molecular chain segments of traditional organic binders move more intensively, and the thermal conductivity increases significantly with the increase in temperature, making it difficult to meet the high-temperature protection requirements of solar collectors in the focused light spot area. And under long-term high-temperature conditions, the organic binder is prone to failure, resulting in a shortened life of the thermal insulation felt. Summary of the Invention

[0005] The purpose of the present invention is to provide an aerogel-based weather-resistant thermal insulation felt and a preparation method thereof, which are used to solve the technical problem that the thermal insulation performance and weather resistance of the thermal insulation felt in the prior art need to be further improved.

[0006] The purpose of the present invention can be achieved by the following technical solutions: A preparation method of an aerogel-based weather-resistant thermal insulation felt includes the following preparation steps:

[0007] S1. Mix a modified binder, ethanol, and modified titanium dioxide evenly to obtain a mixed slurry;

[0008] S2. Place the glass fiber felt in a mold, add the mixed slurry and the modified aerogel base liquid, add ammonia water to adjust the pH to 8 ± 0.5, transfer it to a drying oven at a temperature of 40 - 50 °C, keep it warm and react for 0.5 - 1 h, add the dimethyldiethoxysilane solution, keep it warm and react for 8 - 10 h, elute with n - hexane, and dry to obtain the thermal insulation felt.

[0009] The reaction principle for the preparation of the thermal insulation felt is as follows:

[0010] During the reaction process, adding ammonia water to adjust the solution to be weakly alkaline can accelerate the rate of the polycondensation reaction and promote the formation of the gel network. The OH - ions in ammonia water neutralize the charges on the surface of silicic acid, reducing the electrostatic repulsion between sol particles and making the particles easier to aggregate. The glass fiber felt is immersed in the modified aerogel base liquid and is evenly dispersed in the solution. The hydroxyl groups on the surface of the glass fiber undergo a condensation reaction with the silicon hydroxyl groups in the silica sol to form Si - O - Si, obtaining a precursor of the thermal insulation felt wrapped by aerogel. Dimethyldiethoxysilane hydrolyzes to generate reactive silanol groups, and the silanol groups undergo dehydration condensation with the hydroxyl groups on the surface of the thermal insulation felt precursor to form stable Si - O - Si covalent bonds. The grafted methyl groups are arranged outward to form a low - surface - energy hydrophobic layer, obtaining a hydrophobic thermal insulation felt. N - hexane, as a low - polarity organic solvent, can displace the water molecules and ethanol in the gel network. Drying at 40 - 50 °C promotes the slow volatilization of the solvent, forming a uniform porous structure. Adding in stages can optimize the penetration depth of the solvent and avoid pore collapse, obtaining the thermal insulation felt.

[0011] Further, in step S1, the dosage ratio of the modified binder, ethanol, and modified titanium dioxide is 50 - 70 g: 1000 - 1500 mL: 5 - 8 g; in step S2, the dosage ratio of the modified aerogel base liquid and the mixed slurry is 80 - 100 g: 150 - 200 g, and the impregnation ratio is 1: 30 - 35.

[0012] Further, in step S3, the dimethyldiethoxysilane solution is composed of ethanol and dimethyldiethoxysilane in a volume ratio of 10:1, and the dosage ratio of the gel thermal insulation felt and the dimethyldiethoxysilane solution is 200 - 250 g: 20 - 22 mL; in step S4, the dosage ratio of the thermal insulation felt and n - hexane is 350 - 380 g: 1200 - 1400 mL, and the volumes of n - hexane added for the first and second times are the same.

[0013] Further, the preparation method of the modified aerogel-based liquid is as follows: Put cetyltrimethylammonium bromide, deionized water, ethanol, tetraethyl orthosilicate, and dimethyldiethoxysilane into a reaction kettle, stir for 5 - 10 min, add oxalic acid solution to adjust the pH to 3 ± 0.5, heat up to 40 - 50 °C, keep the temperature for reaction for 30 - 40 min, add N,N-dimethylformamide, and stir for 3 - 5 min to obtain the modified aerogel-based liquid.

[0014] The reaction principle for the preparation of the modified aerogel-based liquid is as follows:

[0015] During the reaction process, tetraethyl orthosilicate and dimethyldiethoxysilane react with water to generate silanols, which further undergo condensation reactions to form a silica network structure. The sol gradually transforms into a gel. Cetyltrimethylammonium bromide, as a cationic surfactant, forms micelles in the solution, provides a template for the hydrolysis and polycondensation of the silicon source, and guides the formation of an ordered mesoporous structure. Adding oxalic acid solution adjusts the reaction system to be weakly acidic, inhibits the rate of the condensation reaction, and keeps the sol stable. N,N-dimethylformamide ensures the uniformity of the reaction system to obtain the modified aerogel-based liquid.

[0016] Further, according to the preparation method of an aerogel-based weather-resistant thermal insulation felt described in claim 3, it is characterized in that the dosage ratio of cetyltrimethylammonium bromide, deionized water, ethanol, tetraethyl orthosilicate, dimethyldiethoxysilane, and N,N-dimethylformamide is 0.05 - 0.10 g : 4 - 6 mL : 7 - 10 g : 1 - 2 g : 4 - 6 mL, and the concentration of the oxalic acid solution is 0.1 - 0.2 mol / mL.

[0017] Further, the modified adhesive is prepared by the following steps:

[0018] B1. Put butyl acrylate, methyl methacrylate, acrylic acid, vinyltrimethoxysilane, ethylene glycol dimethacrylate, deionized water, and sodium dodecylbenzenesulfonate into a reaction kettle, mix them evenly to obtain a mixed emulsion;

[0019] B2. Put ammonium persulfate and deionized water into a reaction kettle, add the mixed emulsion, heat up to 80 - 90 °C, and keep the temperature for reaction for 1 - 2 h to obtain an acrylic emulsion;

[0020] The reaction principle for the preparation of the acrylic emulsion is as follows:

[0021] During the reaction process, butyl acrylate, methyl methacrylate, acrylic acid, vinyltrimethoxysilane, ethylene glycol dimethacrylate, and deionized water are dispersed into tiny droplets under the action of sodium dodecylbenzenesulfonate to form a stable oil-in-water mixed emulsion. Ammonium persulfate decomposes at 80 - 90 °C to generate sulfate radicals, which initiate the opening of the double bonds of the monomers in the mixed emulsion and chain growth to obtain the acrylic emulsion.

[0022] B3. Place the acrylic emulsion in a reaction kettle, heat it up to 40 - 50 °C, add the silicate binder and sodium dodecyl sulfate, then heat it up to 55 - 65 °C and keep it warm for reaction for 3 - 4 h to obtain the modified binder.

[0023] The reaction principle for the preparation of the modified binder is as follows:

[0024] During the reaction process, the silicate powder hydrolyzes into silanol under the action of deionized water, and further, under the action of sodium dodecyl sulfate, it is evenly dispersed and undergoes a condensation reaction with the hydroxyl groups in the acrylic emulsion to obtain the modified binder.

[0025] Furthermore, in step B1, the dosage ratio of butyl acrylate, methyl methacrylate, acrylic acid, vinyltrimethoxysilane, ethylene glycol dimethacrylate, deionized water, and sodium dodecylbenzenesulfonate is 5 - 10 g : 4 - 8 g : 0.2 - 0.5 g : 0.2 - 0.5 g : 0.2 - 0.5 g : 50 - 100 mL : 0.5 - 1 g; in step B2, the dosage ratio of ammonium persulfate, deionized water, and the mixed emulsion is 0.1 - 0.2 g : 80 - 120 mL : 50 - 100 mL; in step B3, the silicate binder is composed of silicate powder and deionized water according to the dosage ratio of 10 g : 50 mL, and the dosage ratio of the acrylic emulsion, silicate binder, and sodium dodecyl sulfate is 3 - 6 mL : 8 - 13 mL : 0.1 - 0.2 g.

[0026] Furthermore, the modified titanium dioxide is obtained by the following preparation steps:

[0027] C1. Place titanium dioxide, ethanol, deionized water, and KH - 570 in a reaction kettle, heat it up to 50 - 60 °C, keep it warm for reaction for 20 - 24 h, and perform post - treatment to obtain olefin - modified titanium dioxide;

[0028] The reaction principle for the preparation of olefin - modified titanium dioxide is as follows:

[0029] During the reaction process, KH - 570 hydrolyzes into silanol under the action of deionized water, and further undergoes a condensation reaction with the hydroxyl groups on titanium dioxide to obtain olefin - modified titanium dioxide.

[0030] C2. Place aliphatic polyurethane acrylate, bis(1 - (2,4 - difluorophenyl) - 3 - pyrrolyl) titanocene, olefin - modified titanium dioxide, and toluene in a reaction kettle, mix them evenly to obtain a mixed oil phase;

[0031] C3. Place the polyvinyl alcohol solution in a reaction kettle, add the mixed oil phase, stir for 2 - 5 min, perform ultraviolet curing, and perform post - treatment to obtain the modified titanium dioxide.

[0032] The preparation reaction principle of the modified titanium dioxide is as follows:

[0033] During the reaction process, polyvinyl alcohol is used as an emulsifier to form an oil-in-water emulsion with the mixed oil phase and the polyvinyl alcohol solution. Under ultraviolet light irradiation, bis(1-(2,4-difluorophenyl)-3-pyrrolyl)titanocene initiates the free radical polymerization reaction of aliphatic polyurethane acrylate and olefin-modified titanium dioxide to form a polymer shell layer. The olefin-modified titanium dioxide has a certain hydrophilicity and migrates from toluene to the surface of the shell layer. After the toluene inside the shell layer volatilizes, the hollow-structured modified titanium dioxide is obtained.

[0034] Furthermore, in step C1, the dosage ratio of the titanium dioxide, ethanol, deionized water, and KH-570 is 3-6 g: 100-120 mL: 10-15 mL: 4-5 g. The post-treatment steps include: after the reaction is completed, wait for the reaction solution to cool to room temperature, perform suction filtration, wash the filter cake with deionized water and ethanol for 1-2 times, transfer it to a drying oven at a temperature of 50-60 °C, and dry it to a constant weight to obtain olefin-modified titanium dioxide; in step C2, the dosage ratio of the aliphatic polyurethane acrylate, bis(1-(2,4-difluorophenyl)-3-pyrrolyl)titanocene, olefin-modified titanium dioxide, and toluene is 2-4 g: 0.5-1 g: 1-1.5 g: 50-100 mL; in step C3, the polyvinyl alcohol solution is composed of deionized water and polyvinyl alcohol in a volume ratio of 100:2, and the volume ratio of the polyvinyl alcohol solution to the mixed oil phase is 80-100: 15-20. The post-treatment steps include: after the reaction is completed, perform suction filtration, wash the filter cake with ethanol for 1-2 times, transfer it to a drying oven at a temperature of 50-60 °C, and dry it to a constant weight to obtain the modified titanium dioxide.

[0035] The present invention also provides an aerogel-based weather-resistant thermal insulation felt, which is prepared by using the preparation method of an aerogel-based weather-resistant thermal insulation felt described above.

[0036] The present invention has the following beneficial effects:

[0037] 1. The present invention uses a modified binder and modified titanium dioxide as reinforcing materials, and a modified aerogel and glass fiber felt as substrates, and prepares a thermal insulation felt by an impregnation method. First, the present invention modifies titanium dioxide with a silane coupling agent to obtain olefin-modified titanium dioxide. The olefin-modified titanium dioxide further undergoes emulsion polymerization with aliphatic polyurethane acrylate to obtain an oil-in-water emulsion, and further forms a modified titanium dioxide with a hollow structure. The hollow structure of the modified titanium dioxide significantly improves the heat insulation performance of the thermal insulation felt through a gas-solid phase composite heat resistance mechanism. At the same time, the closed-cell characteristics of the hollow structure and the hydrophobic modification of the silane synergistically block the water molecule penetration path. Titanium dioxide itself has strong ultraviolet absorption ability, enabling the thermal insulation felt to maintain stable performance under harsh environments such as humidity, heat, and ultraviolet rays. The benzene ring structure in the aliphatic polyurethane acrylate coating layer can efficiently absorb ultraviolet radiation, improving the weather resistance of the thermal insulation felt.

[0038] 2. The present invention also uses ammonium persulfate to initiate a free radical polymerization reaction of monomer butyl acrylate, methyl methacrylate, acrylic acid, vinyltrimethoxysilane, and ethylene glycol dimethacrylate to obtain an acrylic acid emulsion, which is further compounded with a silicate binder to obtain a modified binder. The copolymerization of butyl acrylate and methyl methacrylate forms an alternating structure of hard and soft segments, endowing the binder with excellent flexibility and adhesion strength. When the acrylate chain segment starts to decompose at 200 - 300 °C, the formed silicon-oxygen network can still maintain the integrity of the material, avoiding the melting failure of traditional pure organic binders at high temperatures and improving the high-temperature resistance of the thermal insulation felt. The introduction of vinyltrimethoxysilane makes the polymer chain ends carry hydrolyzable siloxane groups, which can form Si-O-Si chemical bonds with the hydroxyl groups in the silicate binder and glass fiber felt during the curing process, significantly enhancing the organic-inorganic phase interface bonding force during the preparation of the thermal insulation felt, that is, improving the mechanical properties of the thermal insulation felt. Ethylene glycol dimethacrylate is used as a crosslinking agent to construct a three-dimensional network structure, enhancing the cohesive strength of the binder. This binder system has an appropriate viscosity range and rheological properties, which can not only fully infiltrate the aerogel particles but also not cause an increase in material density due to excessive penetration. The curing process can be completed at room temperature through siloxane condensation, significantly reducing the production energy consumption.

[0039] 3. The present invention also uses tetraethyl orthosilicate as a co-precursor, and prepares a modified aerogel-based liquid through the sol-gel method. The modified aerogel-based liquid, a modified binder, ethanol, and modified titanium dioxide are added to a glass fiber mat for impregnation. Further, a dimethyldiethoxysilane solution is added to modify methyl groups on the gel surface. Finally, the solvent is replaced and dried to obtain a thermal insulation mat. The modified aerogel-based liquid prepared through the sol-gel method has a more uniform pore size distribution and a higher cross-linking density in the silicon-oxygen network formed by its hydrolysis and condensation reaction. The combination of this modified aerogel-based liquid and the glass fiber mat not only retains the ultra-low thermal conductivity characteristics of the aerogel nano-porous structure but also significantly improves the mechanical strength of the material through the reinforcement of the fiber skeleton. The controllable hydrolysis rate during the sol-gel process enables the aerogel network to fully penetrate the fiber gaps, forming a three-dimensional interpenetrating structure, effectively avoiding the interface defect problem of traditional composite materials. The organosilicon component in the binder has good chemical compatibility with the aerogel matrix and forms Si-O-Si chemical bonds during the curing process, ensuring a firm bond at the organic-inorganic interface. The dimethyldiethoxysilane solution undergoes a hydrolysis and condensation reaction on the gel surface, improving the hydrophobicity of the thermal insulation mat surface by grafting methyl groups, avoiding the reduction of the thermal insulation performance of the thermal insulation mat due to the intrusion of water molecules. At the same time, the hydrophobic treatment can prevent the swelling deformation and structural collapse of the material caused by water absorption, avoiding the thermal bridge effect formed by the separation of the fiber-matrix interface, and ensuring that the material still maintains a stable pore size distribution and porosity under complex working conditions, improving the long-term stability of the thermal insulation mat in a humid environment. Detailed implementation mode

[0040] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the protection scope of the present invention.

[0041] The glass fiber mat used in the present invention is purchased from Shenyang Tianrui Qicheng Thermal Insulation Materials Co., Ltd., and its thermal conductivity is 0.022.

[0042] The silicate powder used in the present invention is purchased from Woyuan Mineral Products Processing Factory in Lingshou County, and its pH value is 9.7.

[0043] The aliphatic polyurethane acrylate used in the present invention is purchased from Yinhuang (Shanghai) Industrial Co., Ltd., and its brand

[0044] is EBECRYL.

[0045] The titanium dioxide used in the present invention is purchased from Henan Mingzhixin Chemical Products Co., Ltd., and its specific gravity is 4:1.

[0046] Example 1

[0047] This embodiment provides a method for preparing an aerogel-based weather-resistant thermal insulation felt, comprising the following steps:

[0048] S1. Prepare modified titanium dioxide

[0049] Weigh: 30 g of titanium dioxide, 1000 mL of ethanol, 100 mL of deionized water, and 40 g of KH-570, place them in a reaction kettle, heat up to 50 °C, keep the temperature for reaction for 20 h. After the reaction is completed, wait for the reaction solution to cool to room temperature, carry out suction filtration, wash the filter cake once with deionized water and ethanol, transfer it to a drying oven at 50 °C, dry to constant weight, carry out ball milling, and sieve through a 2000-mesh sieve to obtain olefin-modified titanium dioxide;

[0050] Weigh: 20 g of aliphatic polyurethane acrylate, 5 g of bis(1-(2,4-difluorophenyl)-3-pyrrolyl)titanocene dichloride, 10 g of olefin-modified titanium dioxide, and 500 mL of toluene, place them in a reaction kettle, mix evenly to obtain a mixed oil phase;

[0051] Mix deionized water and polyvinyl alcohol evenly according to a volume ratio of 100:2 to obtain a polyvinyl alcohol solution for standby;

[0052] Weigh: 800 mL of the polyvinyl alcohol solution, place it in a reaction kettle, add 150 mL of the mixed oil phase, emulsify for 2 min, carry out ultraviolet curing, the main wavelength of the ultraviolet lamp is 365 nm, the light intensity is 10 mW, the irradiation time is 20 s. After the reaction is completed, carry out suction filtration, wash the filter cake once with ethanol, transfer it to a drying oven at 50 °C, dry to constant weight to obtain modified titanium dioxide.

[0053] S2. Prepare modified binder

[0054] Weigh: 50 g of butyl acrylate, 40 g of methyl methacrylate, 2 g of acrylic acid, 2 g of vinyltrimethoxysilane, 2 g of ethylene glycol dimethacrylate, 500 mL of deionized water, and 5 g of sodium dodecylbenzenesulfonate, place them in a reaction kettle, mix evenly to obtain a mixed emulsion;

[0055] Weigh: 1 g of ammonium persulfate and 800 mL of deionized water, place them in a reaction kettle, add 500 mL of the mixed emulsion, heat up to 80 °C, keep the temperature for reaction for 1 h to obtain an acrylic emulsion;

[0056] Mix silicate powder and deionized water evenly according to a dosage ratio of 10 g:50 mL to obtain a silicate binder for standby;

[0057] Weigh: 30 mL of the acrylic emulsion, place it in a reaction kettle, heat up to 40 °C, add 80 mL of the silicate binder and 1 g of sodium dodecyl sulfate, heat up to 55 °C, keep the temperature for reaction for 3 h to obtain a modified binder.

[0058] S3. Preparation of modified aerogel-based liquid

[0059] Weigh: 0.5 g of cetyltrimethylammonium bromide, 40 mL of deionized water, 70 g of ethanol, 10 g of tetraethyl orthosilicate and 40 mL of dimethyldiethoxysilane, place them in a reaction kettle, stir for 5 min, add 1 mol / mL oxalic acid solution to adjust the pH to 3.1, heat up to 40 °C, keep the temperature for reaction for 30 min, add N,N-dimethylformamide, stir for 3 min to obtain the modified aerogel-based liquid.

[0060] S4. Preparation of thermal insulation felt

[0061] Weigh: 500 g of modified binder, 10000 mL of ethanol and 50 g of modified titanium dioxide, mix them evenly to obtain a mixed slurry;

[0062] Mix ethanol and dimethyldiethoxysilane evenly according to a volume ratio of 10:1 to obtain a dimethyldiethoxysilane solution for standby;

[0063] Weigh: Place the glass fiber felt in a mold, add 800 g of modified aerogel-based liquid and 1500 g of mixed slurry. The impregnation ratio of the glass fiber felt to the modified aerogel-based liquid is 1:30. Add ammonia water to adjust the pH to 8.1, transfer it to a drying oven at 40 °C, keep the temperature for reaction for 0.5 h, add 500 mL of dimethyldiethoxysilane solution, keep the temperature for reaction for 8 h, then add 600 mL of n-hexane, keep the temperature for reaction for 6 h, and then add 600 mL of n-hexane again, keep the temperature for reaction for 24 h to obtain the thermal insulation felt.

[0064] Example 2

[0065] This example provides a preparation method of an aerogel-based weather-resistant thermal insulation felt, including the following steps:

[0066] S1. Preparation of modified titanium dioxide

[0067] Weigh: 45 g of titanium dioxide, 1100 mL of ethanol, 125 mL of deionized water and 45 g of KH-570, place them in a reaction kettle, heat up to 55 °C, keep the temperature for reaction for 22 h. After the reaction is completed, wait for the reaction solution to cool to room temperature, carry out suction filtration, wash the filter cake with deionized water and ethanol twice, transfer it to a drying oven at 55 °C, dry it to constant weight, carry out ball milling, and pass through a 2000-mesh sieve to obtain olefin-modified titanium dioxide;

[0068] Weigh: 30 g of aliphatic polyurethane acrylate, 7 g of bis(1-(2,4-difluorophenyl)-3-pyrrolyl)titanocene dichloride, 12 g of olefin-modified titanium dioxide and 700 mL of toluene, place them in a reaction kettle, and mix them evenly to obtain a mixed oil phase;

[0069] Mix deionized water and polyvinyl alcohol evenly at a volume ratio of 100:2 to obtain a polyvinyl alcohol solution for later use;

[0070] Weigh: Place 900 mL of the polyvinyl alcohol solution in a reaction kettle, add 170 mL of the mixed oil phase, emulsify for 3 min, and then perform ultraviolet curing. The main wavelength of the ultraviolet lamp is 380 nm, the light intensity is 30 mW, and the irradiation time is 25 s. After the reaction is completed, perform suction filtration. Wash the filter cake twice with ethanol, transfer it to a drying oven at 55 °C, and dry it to a constant weight to obtain modified titanium dioxide.

[0071] S2. Preparation of modified binder

[0072] Weigh: Place 70 g of butyl acrylate, 60 g of methyl methacrylate, 3 g of acrylic acid, 3 g of vinyltrimethoxysilane, 3 g of ethylene glycol dimethacrylate, 700 mL of deionized water, and 7 g of sodium dodecylbenzenesulfonate in a reaction kettle and mix evenly to obtain a mixed emulsion;

[0073] Weigh: Place 1.5 g of ammonium persulfate and 100 mL of deionized water in a reaction kettle, add 700 mL of the mixed emulsion, heat up to 85 °C, and keep the temperature for reaction for 1.5 h to obtain an acrylic emulsion;

[0074] Mix the silicate powder and deionized water evenly according to the dosage ratio of 10 g:50 mL to obtain a silicate binder for later use;

[0075] Weigh: Place 45 mL of the acrylic emulsion in a reaction kettle, heat up to 45 °C, add 130 mL of the silicate binder and 15 g of sodium dodecyl sulfate, heat up to 60 °C, and keep the temperature for reaction for 3.5 h to obtain a modified binder.

[0076] S3. Preparation of modified aerogel base liquid

[0077] Weigh: Place 0.7 g of cetyltrimethylammonium bromide, 50 mL of deionized water, 85 g of ethanol, 15 g of tetraethyl orthosilicate, and 50 mL of dimethyldiethoxysilane in a reaction kettle, stir for 7 min, add a 0.15 mol / mL oxalic acid solution to adjust the pH to 3.2, heat up to 45 °C, keep the temperature for reaction for 35 min, add N,N-dimethylformamide, and stir for 4 min to obtain a modified aerogel base liquid.

[0078] S4. Preparation of heat insulation felt

[0079] Weigh: Mix 600 g of the modified binder, 12000 mL of ethanol, and 65 g of the modified titanium dioxide evenly to obtain a mixed slurry;

[0080] Mix ethanol and dimethyldiethoxysilane evenly at a volume ratio of 10:1 to obtain a dimethyldiethoxysilane solution for later use;

[0081] Weighing: Place the glass fiber felt in a mold, add 900 g of the modified aerogel base liquid and 1700 g of the mixed slurry. The impregnation ratio of the glass fiber felt to the modified aerogel base liquid is 1:33. Add ammonia water to adjust the pH to 8.3, transfer it to a drying oven at 45 °C, keep warm and react for 0.5 h. Add 600 mL of the dimethyldiethoxysilane solution, keep warm and react for 9 h, then add 600 mL of n-hexane, keep warm and react for 6 h, and then add 600 mL of n-hexane again, keep warm and react for 26 h to obtain the thermal insulation felt.

[0082] Example 3

[0083] This example provides a preparation method of an aerogel-based weather-resistant thermal insulation felt, which includes the following steps:

[0084] S1. Prepare modified titanium dioxide

[0085] Weighing: Place 60 g of titanium dioxide, 1200 mL of ethanol, 150 mL of deionized water and 50 g of KH-570 in a reaction kettle, heat up to 60 °C, keep warm and react for 24 h. After the reaction is completed, wait for the reaction solution to cool to room temperature, filter by suction, wash the filter cake with deionized water and ethanol twice, transfer it to a drying oven at 60 °C, dry to constant weight, ball mill, and pass through a 2000-mesh sieve to obtain olefin-modified titanium dioxide;

[0086] Weighing: Place 40 g of aliphatic polyurethane acrylate, 10 g of bis(1-(2,4-difluorophenyl)-3-pyrrolyl)titanocene dichloride, 15 g of olefin-modified titanium dioxide and 1000 mL of toluene in a reaction kettle, mix evenly to obtain a mixed oil phase;

[0087] Mix deionized water and polyvinyl alcohol evenly at a volume ratio of 100:2 to obtain a polyvinyl alcohol solution for standby;

[0088] Weighing: Place 1000 mL of the polyvinyl alcohol solution in a reaction kettle, add 200 mL of the mixed oil phase, emulsify for 5 min, and perform ultraviolet curing. The main wavelength of the ultraviolet lamp is 405 nm, the light intensity is 50 mW, and the irradiation time is 30 s. After the reaction is completed, filter by suction, wash the filter cake with ethanol twice, transfer it to a drying oven at 60 °C, dry to constant weight to obtain modified titanium dioxide.

[0089] S2. Prepare modified binder

[0090] Weighing: Place 100 g of butyl acrylate, 80 g of methyl methacrylate, 5 g of acrylic acid, 5 g of vinyltrimethoxysilane, 5 g of ethylene glycol dimethacrylate, 1000 mL of deionized water and 10 g of sodium dodecylbenzenesulfonate in a reaction kettle, mix evenly to obtain a mixed emulsion;

[0091] Weigh: 2 g of ammonium persulfate and 1200 mL of deionized water are placed in a reaction kettle, 1000 mL of mixed emulsion is added, the temperature is raised to 90 °C, and the reaction is kept for 2 h to obtain acrylic emulsion;

[0092] Mix silicate powder and deionized water in a dosage ratio of 10 g:50 mL evenly to obtain silicate binder for standby;

[0093] Weigh: 60 mL of acrylic emulsion is placed in a reaction kettle, the temperature is raised to 50 °C, 130 mL of silicate binder and 2 g of sodium dodecyl sulfate are added, the temperature is raised to 65 °C, and the reaction is kept for 4 h to obtain modified binder.

[0094] S3. Prepare modified aerogel base liquid

[0095] Weigh: 1 g of cetyltrimethylammonium bromide, 60 mL of deionized water, 100 g of ethanol, 20 g of tetraethyl orthosilicate and 60 mL of dimethyldiethoxysilane are placed in a reaction kettle, stirred for 10 min, adjusted to pH = 3.5 with 0.2 mol / mL oxalic acid solution, the temperature is raised to 50 °C, the reaction is kept for 40 min, N,N-dimethylformamide is added, and stirred for 5 min to obtain modified aerogel base liquid.

[0096] S4. Prepare heat insulation felt

[0097] Weigh: 700 g of modified binder, 15000 mL of ethanol and 80 g of modified titanium dioxide are mixed evenly to obtain mixed slurry;

[0098] Mix ethanol and dimethyldiethoxysilane in a volume ratio of 10:1 evenly to obtain dimethyldiethoxysilane solution for standby;

[0099] Weigh: Place the glass fiber felt in a mold, add 1000 g of modified aerogel base liquid and 2000 g of mixed slurry, the impregnation ratio of the glass fiber felt to the modified aerogel base liquid is 1:35, add ammonia water to adjust pH = 8.5, transfer to a drying oven at 50 °C, keep the reaction for 1 h, add 700 mL of dimethyldiethoxysilane solution, keep the reaction for 10 h, add 600 mL of n-hexane, keep the reaction for 6 h, and add 600 mL of n-hexane again, keep the reaction for 30 h to obtain heat insulation felt.

[0100] Comparative Example 1

[0101] The difference between this comparative example and Example 2 is that step S1 is cancelled, and when preparing the heat insulation felt in step S4, modified titanium dioxide is not used.

[0102] Comparative Example 2

[0103] The difference between this comparative example and Example 2 is that step S2 is cancelled, and when preparing the heat insulation felt in step S4, modified binder is not used.

[0104] Comparative Example 3

[0105] The difference between this comparative example and Example 2 is that when preparing the thermal insulation felt in step S4, dimethyldiethoxysilane solution is not used.

[0106] Performance test:

[0107] Referring to the standard GB / T 44440-2024 "Thermal insulation materials - Determination of long-term water absorption by diffusion method", the hydrophobicity rate of the thermal insulation felts prepared in Examples 1-3 and Comparative Examples 1-3 was tested;

[0108] Referring to the standard GB / T 5990-2021 "Refractory materials - Test methods for thermal conductivity, specific heat capacity and thermal diffusivity (hot wire method)", the room temperature thermal conductivity of the thermal insulation felts prepared in Examples 1-3 and Comparative Examples 1-3 was tested;

[0109] Referring to the standard GB / T 10654-2001 "Determination of tensile strength and elongation at break of high polymer porous elastic materials", the tensile strength of the thermal insulation felts prepared in Examples 1-3 and Comparative Examples 1-3 was tested;

[0110] Referring to the standard GB / T 37991-2019 "Test method for reheating linear shrinkage rate of ultra-thin glass - Dilatometer method", the heating linear shrinkage rate of the thermal insulation felts prepared in Examples 1-3 and Comparative Examples 1-3 was tested;

[0111] Referring to the standard GB / T 31899-2015 "Textiles - Weathering tests - Exposure to ultraviolet light", the strength retention rate after weathering test of the thermal insulation felts prepared in Examples 1-3 and Comparative Examples 1-3 was tested. The specific data are shown in Table 1.

[0112] Table 1 - Performance test data table of each sample

[0113]

[0114] Data analysis:

[0115] By comparing and analyzing the data in Table 1 above, the hydrophobicity rate of the thermal insulation felt prepared by the present invention is 98.6%, the room temperature thermal conductivity is 0.025 W·m -1 ·K -1 , the tensile strength is 0.25 Mpa, the heating linear shrinkage rate is 2.5%, and the strength retention rate after weathering test is 70.2%;

[0116] By comparing the hydrophobicity ratio and the thermal conductivity at room temperature after the weather resistance test, it is found that the hydrophobicity and heat insulation performance of Comparative Example 1 and Comparative Example 3 have decreased significantly. This shows that adding modified titanium dioxide during the preparation of the insulation felt, its hollow structure significantly improves the heat insulation performance of the insulation felt through the gas-solid phase composite heat resistance mechanism. At the same time, the closed-cell characteristics of the hollow structure and the hydrophobic modification of silane synergistically block the water molecule penetration path. Titanium dioxide itself has strong ultraviolet absorption ability, enabling the insulation felt to maintain stable performance under harsh environments such as humidity, heat, and ultraviolet rays. The benzene ring structure in the aliphatic polyurethane acrylate coating layer can efficiently absorb ultraviolet radiation, improving the weather resistance of the insulation felt. The dimethyldiethoxysilane solution undergoes hydrolysis and condensation reactions on the gel surface, increasing the hydrophobicity of the insulation felt surface by grafting methyl groups, avoiding the reduction of the insulation performance of the insulation felt due to the intrusion of water molecules. At the same time, the hydrophobic treatment can prevent the swelling deformation and structural collapse of the material caused by water absorption, avoiding the thermal bridge effect formed by the separation of the fiber-matrix interface, ensuring that the material still maintains a stable pore size distribution and porosity under complex working conditions, and improving the long-term stability of the insulation felt in a humid environment;

[0117] By comparing the tensile strength, it is found that the mechanical strength of Comparative Example 2 and Comparative Example 3 has decreased significantly. This shows that adding vinyltrimethoxysilane during the preparation of the insulation felt, the polymer chain ends with hydrolyzable siloxane groups, which can form Si-O-Si chemical bonds with the hydroxyl groups in the silicate binder and the glass fiber mat during the curing process, significantly improving the interfacial bonding force between the organic and inorganic phases during the preparation of the insulation felt, that is, improving the mechanical properties of the insulation felt. Ethylene glycol dimethacrylate is used as a crosslinking agent to construct a three-dimensional network structure, enhancing the cohesive strength of the binder. The modified aerogel-based liquid prepared by the sol-gel method has a more uniform pore size distribution and a higher crosslinking density in the silicon-oxygen network formed by its hydrolysis and condensation reaction. The composite of this modified aerogel-based liquid and the glass fiber mat not only retains the ultra-low thermal conductivity characteristics of the aerogel nanoporous structure but also significantly improves the mechanical strength of the material through the strengthening effect of the fiber skeleton. The controllable hydrolysis rate during the sol-gel process enables the aerogel network to fully penetrate the fiber gaps, forming a three-dimensional interpenetrating structure, effectively avoiding the interface defect problem of traditional composite materials. The organosilicon component in the binder has good chemical compatibility with the aerogel matrix and forms Si-O-Si chemical bond connections during the curing process, ensuring the firm bonding of the organic-inorganic interface;

[0118] By comparing the heat shrinkage rate of the heating wire, it is found that the high-temperature resistance of Comparative Example 2 has decreased significantly. This shows that when preparing the thermal insulation felt, adding the modified binder can form an alternating structure of hard and soft segments through the copolymerization of butyl acrylate and methyl methacrylate, endowing the binder with excellent flexibility and adhesion strength. When the acrylate chain segment starts to decompose at 200 - 300 °C, the formed silicon-oxygen network can still maintain the integrity of the material, avoiding the melting failure of traditional pure organic binders at high temperatures and improving the high-temperature resistance of the thermal insulation felt;

[0119] By comparing the retention rate of strength, it is found that the weather resistance of Comparative Examples 1 - 3 has decreased significantly. This shows that the closed-cell characteristics of the hollow structure of the modified titanium dioxide and the hydrophobic modification of silane cooperate to block the water molecule penetration path. Titanium dioxide itself has strong ultraviolet absorption ability, enabling the thermal insulation felt to maintain stable performance under harsh environments such as humidity and ultraviolet rays. The benzene ring structure in the aliphatic polyurethane acrylate coating layer can efficiently absorb ultraviolet radiation, improving the weather resistance of the thermal insulation felt; the modified binder can form an alternating structure of hard and soft segments through the copolymerization of butyl acrylate and methyl methacrylate, endowing the binder with excellent flexibility and adhesion strength. When the acrylate chain segment starts to decompose at 200 - 300 °C, the formed silicon-oxygen network can still maintain the integrity of the material, avoiding the melting failure of traditional pure organic binders at high temperatures and improving the high-temperature resistance of the thermal insulation felt; the dimethyldiethoxysilane solution undergoes hydrolysis and condensation reaction on the gel surface, improving the hydrophobicity of the thermal insulation felt surface by grafting methyl groups, avoiding the reduction of the thermal insulation performance of the thermal insulation felt due to the intrusion of water molecules. At the same time, the hydrophobic treatment can prevent the swelling deformation and structural collapse of the material caused by water absorption, avoiding the thermal bridge effect formed by the separation of the fiber-matrix interface, and ensuring that the material still maintains a stable pore size distribution and porosity under complex working conditions, improving the long-term stability of the thermal insulation felt in a humid environment.

[0120] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to only the specific implementation manners. Obviously, many modifications and variations can be made according to the content of this specification. These embodiments are selected and specifically described in this specification to better explain the principles and practical applications of the present invention, so that those skilled in the art in the relevant technical field can well understand and utilize the present invention. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. A method for preparing an aerogel-based weather-resistant thermal insulation felt, characterized in that: The method comprises the following preparation steps: S1, uniformly mixing the modified binder, ethanol and modified titanium dioxide to obtain a mixed slurry; S2. Place the glass fiber felt in a mold, add modified aerogel base liquid and mixed slurry, add ammonia water to adjust the pH to 8±0.5, transfer to a drying oven at a temperature of 40-50°C, keep warm for 0.5-1h, add dimethyldiethoxysilane solution, keep warm for 8-10h, elute with n-hexane, dry, and obtain the thermal insulation felt.

2. The method for preparing an aerogel-based weather-resistant thermal insulation felt according to claim 1, characterized in that: In step S1, the dosage ratio of the modified binder, ethanol and modified titanium dioxide is 50-70g:1000-1500mL:5-8g; in step S2, the dosage ratio of the modified aerogel base liquid, the mixed slurry and the dimethyldiethoxysilane solution is 80-100g:150-200g:50-70mL, the dimethyldiethoxysilane solution is composed of ethanol and dimethyldiethoxysilane in a volume ratio of 10:1, and the impregnation ratio of the glass fiber felt and the modified aerogel base liquid is 1:30-35.

3. The method for preparing an aerogel-based weather-resistant thermal insulation felt according to claim 1, characterized in that: The preparation method of the modified aerogel base liquid is as follows: hexadecyltrimethylammonium bromide, deionized water, ethanol, ethyl orthosilicate and dimethyldiethoxysilane are placed in a reaction kettle, stirred for 5-10 minutes, oxalic acid solution is added to adjust the pH value to 3±0.5, the temperature is raised to 40-50° C., the temperature is kept for reaction for 30-40 minutes, N,N-dimethylformamide is added, and stirred for 3-5 minutes to obtain the modified aerogel base liquid.

4. The method for preparing an aerogel-based weather-resistant thermal insulation felt according to claim 3, characterized in that: The dosage ratio of hexadecyltrimethylammonium bromide, deionized water, ethanol, ethyl orthosilicate, dimethyldiethoxysilane and N,N-dimethylformamide is 0.05-0.10 g:4-6 mL:7-10 g:1-2 g:4-6 mL, and the concentration of the oxalic acid solution is 0.1-0.2 mol / mL.

5. The method for preparing an aerogel-based weather-resistant thermal insulation felt according to claim 1, characterized in that: The modified adhesive is prepared by the following steps: B1, placing butyl acrylate, methyl methacrylate, acrylic acid, vinyl trimethoxysilane, ethylene glycol dimethacrylate, deionized water and sodium dodecylbenzene sulfonate in a reaction kettle, mixing evenly to obtain a mixed emulsion; B2. Place ammonium persulfate and deionized water in a reaction kettle, add the mixed emulsion, heat to 80-90° C., and keep the temperature for 1-2 hours to obtain an acrylic emulsion; B3. Place the acrylic emulsion in a reaction kettle, heat it to 40-50°C, add silicate binder and sodium dodecyl sulfate, heat it to 55-65°C, and keep it warm for 3-4 hours to obtain a modified binder.

6. The method for preparing an aerogel-based weather-resistant thermal insulation felt according to claim 5, characterized in that: In step B1, the amount ratio of butyl acrylate, methyl methacrylate, acrylic acid, vinyl trimethoxysilane, ethylene glycol dimethacrylate, deionized water and sodium dodecylbenzene sulfonate is 5-10g:4-8g:0.2-0.5g:0.2-0.5g:0.2-0.5g:50-100mL:0.5-1g; in step B2, the amount ratio of ammonium persulfate, deionized water and mixed emulsion is 0.1-0.2g:80-120mL:50-100mL; in step B3, the silicate binder is composed of silicate powder and deionized water in a ratio of 10g:50mL, and the amount ratio of the acrylic emulsion, silicate binder and sodium dodecyl sulfate is 3-6mL:8-13mL:0.1-0.2g.

7. The method for preparing an aerogel-based weather-resistant thermal insulation felt according to claim 1, characterized in that: The modified titanium dioxide is obtained by the following preparation steps: C1. Titanium dioxide, ethanol, deionized water and KH-570 are placed in a reaction kettle, heated to 50-60°C, kept warm for 20-24 hours, and post-treated to obtain olefin-modified titanium dioxide; C2, placing aliphatic polyurethane acrylate, bis(1-(2,4-difluorophenyl)-3-pyrrolyl) titanocene, olefin-modified titanium dioxide and toluene in a reaction kettle, mixing them evenly to obtain a mixed oil phase; C3. Place the polyvinyl alcohol solution in a reaction kettle, add the mixed oil phase, stir for 2-5 minutes, UV cure, and post-treat to obtain modified titanium dioxide.

8. The method for preparing an aerogel-based weather-resistant thermal insulation felt according to claim 7, characterized in that: In step C1, the amount ratio of the titanium dioxide, ethanol, deionized water and KH-570 is 3-6g:100-120mL:10-15mL:4-5g; in step C2, the amount ratio of the aliphatic polyurethane acrylate, bis(1-(2,4-difluorophenyl)-3-pyrrolyl) titanocene, olefin-modified titanium dioxide and toluene is 2-4g:0.5-1g:1-1.5g:50-100mL; in step C3, the polyvinyl alcohol solution is composed of deionized water and polyvinyl alcohol in a volume ratio of 100:2, and the volume ratio of the polyvinyl alcohol solution to the mixed oil phase is 80-100:15-20.

9. An aerogel-based weather-resistant thermal insulation felt, characterized in that: The aerogel-based weather-resistant thermal insulation felt is prepared by the method for preparing an aerogel-based weather-resistant thermal insulation felt as described in any one of claims 1 to 8.

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