Highly flame-retardant and high-strength silicone aerogel, and preparation method and application thereof
By introducing aminosilanes and epoxy glycidyl ethers into the silicone aerogel framework and combining them with high-temperature impregnation reactive flame retardants, a high-strength, high-flame-retardant silicone aerogel was prepared, solving the problems of poor mechanical properties and flammability, and making it suitable for building and medium- and low-temperature thermal insulation applications.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- EAST CHINA UNIV OF SCI & TECH
- Filing Date
- 2023-09-20
- Publication Date
- 2026-08-04
AI Technical Summary
Existing organosilicon aerogels have poor mechanical properties and are flammable, which limits their industrial application and safety.
By introducing aminosilane and epoxy glycidyl ether to form a silica framework, and using high-temperature impregnation of reactive flame retardants to react on the aerogel surface, high flame retardancy and high strength organosilicon aerogels are prepared, avoiding any impact on their mechanical properties.
The preparation process of organosilicon aerogel, which achieves high strength and high flame retardancy, is simple, reduces production costs, expands its application in building and medium- and low-temperature thermal insulation, and improves safety.
Smart Images
Figure CN117126452B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of organosilicon aerogel technology, and in particular to a highly flame-retardant, high-strength organosilicon aerogel, its preparation method, and its applications. Background Technology
[0002] Organosilicon aerogel is a lightweight, highly porous polymer material. It consists of nano-sol particles or polymer molecules with a rich nanoporous structure. These structural characteristics give it low thermal conductivity, high surface area, and excellent thermal insulation properties, leading to its widespread application in building materials, catalysis, aerospace, and other fields. However, its drawbacks are also significant, primarily its high cost and poor mechanical properties. These shortcomings pose a major obstacle to its further industrialization.
[0003] To address the poor mechanical properties of organosilicon aerogels, scholars both domestically and internationally have conducted numerous attempts and studies. One enhancement method involves introducing organic polymers, allowing them to react onto the silica backbone, and utilizing the ease with which organic polymers undergo cross-linking reactions to further strengthen the aerogel's backbone strength, thereby improving the mechanical strength of the organosilicon aerogel.
[0004] Researchers at Tsinghua University, including Yang Hailong, prepared polymer-reinforced silicone aerogels by using tetraethyl orthosilicate as a raw material and KH550 as a crosslinking agent to graft toluene diisocyanate onto a silica framework, followed by atmospheric pressure drying. While this method enhances the mechanical properties of silicone aerogels, its uncontrollable shrinkage under atmospheric pressure drying limits its practical application. Other researchers abroad have used polyurea, polystyrene, and epoxy polymers for reinforcement, but these methods mostly rely on supercritical drying, resulting in limited mechanical strength enhancement. Furthermore, none of these methods have solved the problem of matrix flammability caused by polymer-reinforced silicone aerogels, posing a potential hazard for future use. Summary of the Invention
[0005] The purpose of this invention is to provide a high flame retardant, high-strength organosilicon aerogel, its preparation method, and its application.
[0006] The objective of this invention can be achieved through the following technical solution: a method for preparing a highly flame-retardant and high-strength organosilicon aerogel, the method comprising the following steps:
[0007] Preparation of high-strength organosilicon aerogel: Aminosilane, glycidyl ether and an appropriate amount of deionized water are mixed in an alcohol solvent and stirred until hydrolysis is achieved. Then, an alkaline catalyst is added and stirred to obtain organosilicon sol. The organosilicon sol is transferred to a sealed container and heated for aging to obtain organosilicon wet gel. Then, it is dried at normal pressure to obtain high-strength organosilicon aerogel.
[0008] High-temperature impregnation reactive flame retardant: The flame retardant is dissolved in an alcohol solvent, then a high-strength silicone aerogel is placed in a container, and the flame retardant alcohol solution is poured into the container. The container is then sealed and placed at a high temperature to allow the flame retardant to react with the high-strength silicone aerogel. After the reaction is complete, the aerogel is removed and the unreacted flame retardant is washed with an alcohol solvent. Then, it is dried at normal pressure until the alcohol solvent is completely evaporated, finally obtaining a high-flame-retardant, high-strength silicone aerogel.
[0009] Preferably, in the organosilicon sol, the mass ratio of aminosilane to glycidyl ether is (20-80):(40-80), the mass fraction of solute is 15-60%, the amount of deionized water added is 4-6 times the molar amount of aminosilane, and the amount of catalyst added is 0-1% of the total mass.
[0010] More preferably, the amount of deionized water added is 5 times the molar amount of aminosilane.
[0011] Preferably, the aminosilane is one or more of 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldimethoxysilane, or 3-aminopropylmethyldiethoxysilane.
[0012] Preferably, the epoxy glycidyl ether is one or more of ethylene glycol diglycidyl ether, resorcinol diglycidyl ether, or diglycidyl ether.
[0013] Preferably, the alcohol solvent used in the preparation of high-strength silicone aerogel is one or more of ethanol, methanol, ethylene glycol, or isopropanol.
[0014] Preferably, the catalyst is one or more of ammonia, ammonium fluoride, or tetramethylammonium hydroxide.
[0015] Preferably, the stirring time for complete hydrolysis of aminosilane is 10-30 min, the heating aging temperature is 60-120℃, the time is 12-72 h, and the drying time is 24-72 h.
[0016] Preferably, the flame retardant is one or more of dimethyl methylphosphonate, diethyl ethyl phosphate, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, or N,N-(2-hydroxyethyl)aminomethyl phosphate.
[0017] Preferably, the solvent for dissolving the flame retardant and the alcohol solvent for washing are one or more of ethanol, methanol, ethylene glycol or isopropanol.
[0018] Preferably, when the flame retardant is dimethyl methylphosphonate, deionized water is added to the flame retardant alcohol solution.
[0019] Preferably, the reaction temperature between the flame retardant and the high-strength silicone aerogel is 80℃-150℃, and the reaction time is 12-72 hours. This invention fully utilizes the porous nature of aerogels and the high reactivity of epoxy groups. By employing a high-temperature impregnation process, the flame retardant can be reacted onto the surface of the aerogel framework without affecting its mechanical properties, thereby achieving a flame-retardant effect. This further expands the application space of polymer-reinforced silicone aerogels, and the manufacturing method is simple and easy to implement, suitable for industrial production.
[0020] A highly flame-retardant and high-strength organosilicon aerogel prepared by the above method.
[0021] An application of the above-mentioned high flame retardant and high strength organosilicon aerogel is to apply the aerogel to building materials, walls, and medium and low temperature thermal insulation.
[0022] In the preparation method of this invention, an epoxy compound is introduced as a polymer reinforcing phase, and aminosilane is directly used as a silicon source to form a silica framework, instead of using it as a crosslinking agent. This provides more adhesion sites for the epoxy polymer, greatly improving the degree of crosslinking of the framework. The resulting aerogel not only has a superior double-crosslinked three-dimensional microstructure, but also exhibits significantly improved mechanical strength. The self-catalytic properties of aminosilane are utilized during the preparation process, eliminating the need for multiple catalyst additions and solvent replacement steps required in traditional silica aerogel preparation. Furthermore, a non-shrinking aerogel can be obtained directly through atmospheric pressure drying, significantly reducing production costs. More importantly, the surface of the resulting organosilicon aerogel is rich in active epoxy functional groups, providing favorable conditions for the introduction of reactive flame retardants. High-temperature impregnation for surface modification does not affect the already formed high-strength framework; flame retardant molecules only react on the framework surface.
[0023] When exposed to an open flame, the flame retardant generates non-flammable gas, diluting the concentration of flammable gas, effectively reducing the thermal effect of the material during combustion and decomposition, and increasing the amount of carbonization, hindering the transfer of oxygen and heat, which can effectively prevent the further spread of the flame.
[0024] Compared with the prior art, the present invention has the following beneficial effects:
[0025] 1. The organosilicon aerogel of the present invention not only has high mechanical strength, but also solves the flammability problem caused by polymer-reinforced organosilicon aerogel, making it safe to use in the construction industry, wall surfaces and medium and low temperature insulation fields;
[0026] 2. The preparation method of the high flame retardant and high strength epoxy polymer reinforced silicone aerogel of the present invention is simple, does not require solvent exchange and other steps, and the finished product can be obtained directly by atmospheric pressure drying, which greatly reduces the preparation cost. The process is simple, easy to implement and low cost.
[0027] 3. This invention utilizes the abundant epoxy groups on the surface of the aerogel through high-temperature impregnation to successfully add reactive flame retardants, eliminating the flammability defects associated with polymer-reinforced silicone aerogels without affecting their original performance. This effectively improves their safety index and expands their application scenarios. Combined with its high strength and ease of preparation, it is highly suitable for industrial production and can achieve long-lasting thermal insulation in fields such as building construction, wall applications, and medium- and low-temperature thermal insulation. Attached Figure Description
[0028] Figure 1 A photograph of the high flame-retardant, high-strength silicone aerogel from Example 7;
[0029] Figure 2 A schematic diagram of the microstructure of high flame-retardant and high-strength organosilicon aerogel;
[0030] Figure 3 These are photographs of the alcohol lamp burning in Blank Example 1 and Examples 3-6;
[0031] Figure 4 Scanning electron microscope (SEM) images of blank example 1 and examples 3-6. Detailed Implementation
[0032] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.
[0033] A highly flame-retardant, high-strength organosilicon aerogel, its preparation method, and its application. The preparation method includes the following steps:
[0034] Preparation of high-strength organosilicon aerogel: Aminosilane, glycidyl ether, and an appropriate amount of deionized water were mixed in an alcohol solvent and stirred in a water bath until hydrolysis occurred. Then, an alkaline catalyst was added and the mixture was stirred again to obtain an organosilicon sol. The organosilicon sol was transferred to a sealed container and aged at high temperature to obtain a wet organosilicon gel. This wet gel was then dried at normal pressure to obtain a high-strength organosilicon aerogel.
[0035] In the organosilicon sol, the mass ratio of aminosilane to glycidyl ether is (20-80):(40-80), the mass fraction of the solute is 15-60%, and the amount of deionized water added is 5 times the molar amount of aminosilane; the amount of catalyst added is 0-1% of the total mass. The aminosilane is one or more of 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldimethoxysilane, or 3-aminopropylmethyldiethoxysilane. The epoxy glycidyl ether is one or more of ethylene glycol diglycidyl ether, resorcinol diglycidyl ether, or diglycidyl ether; the alcohol solvent is one or more of ethanol, methanol, ethylene glycol, or isopropanol; the catalyst is one or more of ammonia, ammonium fluoride, or tetramethylammonium hydroxide. The stirring time for complete hydrolysis of silane is 10-30 minutes, and the stirring time should not exceed 5 minutes. The heating and aging temperature is 60-120℃, the time is 12-48 hours, and the drying time is 24-72 hours.
[0036] High-temperature impregnation reactive flame retardant: The flame retardant is dissolved in an alcohol solution, then a high-strength silicone aerogel is placed in a container, and the flame retardant alcohol solution is poured into the container. The container is then sealed and placed at high temperature to allow the flame retardant to react with the high-strength silicone aerogel. After the reaction is complete, the aerogel is removed and washed with an alcohol solution to remove unreacted flame retardant. It is then dried at normal pressure until all the alcohol solvent has evaporated, finally yielding a highly flame-retardant, high-strength silicone aerogel.
[0037] The flame retardant is one or more of dimethyl methylphosphonate, diethyl ethyl phosphate, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, or N,N-(2-hydroxyethyl)aminomethyl phosphate. The alcohol solvent used to dissolve the flame retardant and for washing is one or more of ethanol, methanol, ethylene glycol, or isopropanol. The reaction temperature of the flame retardant is 80℃-150℃, and the reaction time is 12-72 hours.
[0038] Blank example 1
[0039] A certain amount of 3-aminopropyltrimethoxysilane, deionized water, and resorcinol diglycidyl ether were weighed and added to an ethanol solution, and stirred for 10 min to hydrolyze the aminosilane. The mass ratio of 3-aminopropyltrimethoxysilane to resorcinol diglycidyl ether was 1:2, the amount of deionized water added was 5 times the molar amount of aminosilane, and the mass concentration of the solution was 30%. After hydrolysis, 8% ammonia solution was added and stirred for 5 min to obtain an organosilicon precursor solution. The amount of ammonia solution added was 0.5% of the solution mass.
[0040] The container is sealed and placed in an oven at 100°C for 24 hours to obtain a white wet gel. The silicone wet gel is dried at room temperature for 12 hours, then placed in an oven at 50°C for 12 hours, and then placed in an oven at 80°C for 2 hours to obtain a high-strength silicone aerogel.
[0041] Example 1
[0042] A certain amount of 3-aminopropyltrimethoxysilane, deionized water, and resorcinol diglycidyl ether were weighed and added to an ethanol solution, and stirred for 10 min to hydrolyze the aminosilane. The mass ratio of 3-aminopropyltrimethoxysilane to resorcinol diglycidyl ether was 1:2, the amount of deionized water added was 5 times the molar amount of aminosilane, and the mass concentration of the solution was 30%. After hydrolysis, 8% ammonia solution was added and stirred for 5 min to obtain an organosilicon precursor solution. The amount of ammonia solution added was 0.5% of the solution mass. The container was sealed and placed in an oven at 100℃ for 24 h to obtain a white wet gel. The organosilicon wet gel was dried at room temperature for 12 h, then placed in an oven at 50℃ for 12 h, and then placed in an oven at 80℃ for 2 h to obtain a high-strength organosilicon aerogel.
[0043] High-strength silicone aerogel was encapsulated in a container. A certain amount of dimethyl methylphosphonate and deionized water were weighed out, dissolved in ethanol, and poured into the container. The mass concentration of dimethyl methylphosphonate was 5%, and the amount of deionized water was 5 times the molar amount of dimethyl methylphosphonate. The container was then sealed and placed in an oven at 100°C for 24 hours to react. After the reaction was complete, the unreacted flame retardant was washed three times with ethanol, and then dried at normal pressure for 24 hours to obtain a highly flame-retardant, high-strength silicone aerogel.
[0044] Example 2
[0045] A certain amount of 3-aminopropyltrimethoxysilane, deionized water, and resorcinol diglycidyl ether were weighed and added to an ethanol solution, and stirred for 10 min to hydrolyze the aminosilane. The mass ratio of 3-aminopropyltrimethoxysilane to resorcinol diglycidyl ether was 1:2, the amount of deionized water added was 5 times the molar amount of aminosilane, and the mass concentration of the solution was 30%. After hydrolysis, 8% ammonia solution was added and stirred for 5 min to obtain an organosilicon precursor solution. The amount of ammonia solution added was 0.5% of the solution mass. The container was sealed and placed in an oven at 100℃ for 24 h to obtain a white wet gel. The organosilicon wet gel was dried at room temperature for 12 h, then placed in an oven at 50℃ for 12 h, and then placed in an oven at 80℃ for 2 h to obtain a high-strength organosilicon aerogel.
[0046] High-strength silicone aerogel was encapsulated in a container, and then a 5% (w / w) methanol solution of N,N-(2-hydroxyethyl)aminomethyl phosphate was poured in. The container was then sealed and placed in an oven at 100°C for 24 hours. After the reaction was complete, the unreacted flame retardant was washed three times with ethanol, and then dried at normal pressure for 24 hours to obtain a high-flame-retardant, high-strength silicone aerogel.
[0047] Example 3
[0048] A certain amount of 3-aminopropyltrimethoxysilane, deionized water, and resorcinol diglycidyl ether were weighed and added to an ethanol solution, and stirred for 10 min to hydrolyze the aminosilane. The mass ratio of 3-aminopropyltrimethoxysilane to resorcinol diglycidyl ether was 1:2, the amount of deionized water added was 5 times the molar amount of aminosilane, and the mass concentration of the solution was 30%. After hydrolysis, 8% ammonia solution was added and stirred for 5 min to obtain an organosilicon precursor solution. The amount of ammonia solution added was 0.5% of the solution mass. The container was sealed and placed in an oven at 100℃ for 24 h to obtain a white wet gel. The organosilicon wet gel was dried at room temperature for 12 h, then placed in an oven at 50℃ for 12 h, and then placed in an oven at 80℃ for 2 h to obtain a high-strength organosilicon aerogel.
[0049] High-strength silicone aerogel was encapsulated in a container, and then a 5% (w / w) ethanol solution of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide was poured into it. The container was then sealed and placed in an oven at 100°C for 24 hours. After the reaction was complete, the unreacted flame retardant was washed three times with ethanol, and then dried at normal pressure for 24 hours to obtain a high-flame-retardant, high-strength silicone aerogel.
[0050] Example 4
[0051] A certain amount of 3-aminopropyltrimethoxysilane, deionized water, and resorcinol diglycidyl ether were weighed and added to an ethanol solution, and stirred for 10 min to hydrolyze the aminosilane. The mass ratio of 3-aminopropyltrimethoxysilane to resorcinol diglycidyl ether was 1:2, the amount of deionized water added was 5 times the molar amount of aminosilane, and the mass concentration of the solution was 30%. After hydrolysis, 8% ammonia solution was added and stirred for 5 min to obtain an organosilicon precursor solution. The amount of ammonia solution added was 0.5% of the solution mass. The container was sealed and placed in an oven at 100℃ for 24 h to obtain a white wet gel. The organosilicon wet gel was dried at room temperature for 12 h, then placed in an oven at 50℃ for 12 h, and then placed in an oven at 80℃ for 2 h to obtain a high-strength organosilicon aerogel.
[0052] High-strength silicone aerogel was encapsulated in a container, and then a 10% (w / w) ethanol solution of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide was poured into it. The container was then sealed and placed in an oven at 100°C for 24 hours. After the reaction was complete, the unreacted flame retardant was washed three times with ethanol, and then dried at normal pressure for 24 hours to obtain a high-flame-retardant, high-strength silicone aerogel.
[0053] Example 5
[0054] A certain amount of 3-aminopropyltrimethoxysilane, deionized water, and resorcinol diglycidyl ether were weighed and added to an ethanol solution, and stirred for 10 min to hydrolyze the aminosilane. The mass ratio of 3-aminopropyltrimethoxysilane to resorcinol diglycidyl ether was 1:2, the amount of deionized water added was 5 times the molar amount of aminosilane, and the mass concentration of the solution was 30%. After hydrolysis, 8% ammonia solution was added and stirred for 5 min to obtain an organosilicon precursor solution. The amount of ammonia solution added was 0.5% of the solution mass. The container was sealed and placed in an oven at 100℃ for 24 h to obtain a white wet gel. The organosilicon wet gel was dried at room temperature for 12 h, then placed in an oven at 50℃ for 12 h, and then placed in an oven at 80℃ for 2 h to obtain a high-strength organosilicon aerogel.
[0055] High-strength silicone aerogel was encapsulated in a container, and then a 15% (w / w) ethanol solution of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide was poured into it. The container was then sealed and placed in an oven at 100°C for 24 hours. After the reaction was complete, the unreacted flame retardant was washed three times with ethanol, and then dried at atmospheric pressure for 24 hours to obtain a high-flame-retardant, high-strength silicone aerogel.
[0056] Example 6
[0057] A certain amount of 3-aminopropyltrimethoxysilane, deionized water, and resorcinol diglycidyl ether were weighed and added to an ethanol solution, and stirred for 10 min to hydrolyze the aminosilane. The mass ratio of 3-aminopropyltrimethoxysilane to resorcinol diglycidyl ether was 1:2, the amount of deionized water added was 5 times the molar amount of aminosilane, and the mass concentration of the solution was 30%. After hydrolysis, 8% ammonia solution was added and stirred for 5 min to obtain an organosilicon precursor solution. The amount of ammonia solution added was 0.5% of the solution mass. The container was sealed and placed in an oven at 100℃ for 24 h to obtain a white wet gel. The organosilicon wet gel was dried at room temperature for 12 h, then placed in an oven at 50℃ for 12 h, and then placed in an oven at 80℃ for 2 h to obtain a high-strength organosilicon aerogel.
[0058] High-strength silicone aerogel was encapsulated in a container, and then a 20% (w / w) ethanol solution of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide was poured into it. The container was then sealed and placed in an oven at 100°C for 24 hours. After the reaction was complete, the unreacted flame retardant was washed three times with ethanol, and then dried at atmospheric pressure for 24 hours to obtain a high-flame-retardant, high-strength silicone aerogel.
[0059] Figure 3 These are photographs of the samples from the combustion tests conducted on Blank Example 1 and Examples 3-6. It can be seen that the sample without the addition of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide was completely burned after 30 seconds. With the addition of the flame retardant, the flame-retardant effect of the aerogel became increasingly pronounced; even with continuous ignition, it did not burn violently and was self-extinguishing. The figures clearly show that when the addition amount reached 15% (Example 5), the aerogel maintained its structural integrity after being ignited by an alcohol lamp for 30 seconds, with only the areas in contact with the flame undergoing carbonization. Furthermore, no continuous open flame was observed during combustion, indicating that the addition of the flame retardant significantly reduced its flammability.
[0060] Figure 2 This is a schematic diagram of the structure of a highly flame-retardant and high-strength silicone aerogel obtained after adding a reactive flame retardant. The addition of the flame retardant does not destroy the structural integrity of the aerogel; it simply reacts and adheres to the surface of the intricately cross-linked framework.
[0061] like Figure 4 The images shown are scanning electron microscope (SEM) images of blank example 1 and examples 3-6, respectively. ICP testing revealed that the phosphorus (P) content in examples 3-6 was 1.5%, 2.24%, 3.16%, and 3.26%, respectively, indicating that the flame retardant had successfully adhered to the framework. Furthermore, the microporous structure of the aerogel did not show significant changes, demonstrating that the flame retardant did not disrupt the original structure of the aerogel.
[0062] Example 7
[0063] A certain amount of 3-aminopropyltrimethoxysilane, deionized water, and resorcinol diglycidyl ether were weighed and added to an ethanol solution, and stirred for 10 min to hydrolyze the aminosilane. The mass ratio of 3-aminopropyltrimethoxysilane to resorcinol diglycidyl ether was 1:2, the amount of deionized water added was 5 times the molar amount of aminosilane, and the mass concentration of the solution was 30%. After hydrolysis, 8% ammonia solution was added and stirred for 5 min to obtain an organosilicon precursor solution. The amount of ammonia solution added was 0.5% of the solution mass. The container was sealed and placed in an oven at 100℃ for 24 h to obtain a white wet gel. The organosilicon wet gel was dried at room temperature for 12 h, then placed in an oven at 50℃ for 12 h, and then placed in an oven at 80℃ for 2 h to obtain a high-strength organosilicon aerogel.
[0064] High-strength silicone aerogel was encapsulated in a container, and then a 20% (w / w) ethanol solution of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide was poured into it. The container was then sealed and placed in an oven at 120°C for 24 hours. After the reaction was complete, the unreacted flame retardant was washed three times with ethanol, and then dried at normal pressure for 24 hours to obtain a high-flame-retardant, high-strength silicone aerogel.
[0065] Figure 1 The aerogel plate prepared in this embodiment is lightweight and can be stably placed on leaves.
[0066] Example 8
[0067] A certain amount of 3-aminopropyltrimethoxysilane, deionized water, and resorcinol diglycidyl ether were weighed and added to an ethanol solution, and stirred for 10 min to hydrolyze the aminosilane. The mass ratio of 3-aminopropyltrimethoxysilane to resorcinol diglycidyl ether was 1:2, the amount of deionized water added was 5 times the molar amount of aminosilane, and the mass concentration of the solution was 30%. After hydrolysis, 8% ammonia solution was added and stirred for 5 min to obtain an organosilicon precursor solution. The amount of ammonia solution added was 0.5% of the solution mass. The container was sealed and placed in an oven at 100℃ for 24 h to obtain a white wet gel. The organosilicon wet gel was dried at room temperature for 12 h, then placed in an oven at 50℃ for 12 h, and then placed in an oven at 80℃ for 2 h to obtain a high-strength organosilicon aerogel.
[0068] High-strength silicone aerogel was encapsulated in a container, and then a 20% (w / w) ethanol solution of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide was poured into it. The container was then sealed and placed in an oven at 100°C for 48 hours. After the reaction was complete, the unreacted flame retardant was washed three times with ethanol, and then dried at atmospheric pressure for 24 hours to obtain a high-flame-retardant, high-strength silicone aerogel.
[0069] The basic physical parameters of the samples obtained from each embodiment are summarized in Table 1 below.
[0070] Table 1
[0071]
[0072] LOI is the limiting oxygen index of the sample, indicating the minimum oxygen concentration required for combustion. Thermal conductivity is measured at room temperature using a Netzsch HFM446s instrument. Compression modulus was measured using an Instron 3367 universal testing machine. THR is the total heat released during combustion, measured by a cone calorimeter. The sample size was 100×100×5mm, and the radiation intensity was 50KW / m². 2 .
[0073] The difference between Example 1 and the blank group 1 is that Example 1 was impregnated at high temperature with a 5% (w / w) ethanol solution of dimethyl methylphosphonate. The addition of deionized water is intended to address the fact that dimethyl methylphosphonate requires hydrolysis to become reactive. After high-temperature impregnation, the flame retardant reacts to the aerogel surface, leading to an increase in mass and thus a slight increase in density. However, its flame retardant properties are significantly improved, the heat release is significantly reduced, and it is not easily ignited, while its mechanical properties remain unaffected.
[0074] Compared with Example 1, Examples 2 and 3 changed the type of flame retardant. Due to the structural differences of the three flame retardants, their reactions and flame retardancy will be different.
[0075] Examples 3-6 primarily alter the mass concentration of the flame retardant impregnation solution. Higher concentrations result in more flame retardant reacting on the aerogel surface, thus leading to better flame retardant performance. However, high concentrations of the flame retardant alcohol solution also cause a greater increase in the density of the final aerogel. Nevertheless, it has virtually no impact on the mechanical properties of the aerogel.
[0076] The difference between Examples 7 and 8 and Example 6 is that the temperature and reaction time of the flame retardant reaction are increased, which promotes the chemical reaction between the flame retardant and the matrix, thereby obtaining a larger adhesion amount and better flame retardant performance.
[0077] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.
Claims
1. A method for preparing a highly flame-retardant, high-strength organosilicon aerogel, characterized in that, The method includes the following steps: Preparation of high-strength organosilicon aerogel: aminosilane, glycidyl ether and deionized water are mixed in an alcohol solvent, stirred until hydrolysis is achieved, then a catalyst is added and stirred to obtain organosilicon sol. The organosilicon sol is heated and aged to obtain organosilicon wet gel, and then dried at normal pressure to obtain high-strength organosilicon aerogel. High-temperature impregnation reactive flame retardant: The flame retardant is dissolved in an alcohol solvent. The high-strength organosilicon aerogel is placed in a container, and the flame retardant alcohol solution is poured into the container. The container is then sealed and placed at high temperature to allow the flame retardant to react with the high-strength organosilicon aerogel. After the reaction is complete, the aerogel is removed and the unreacted flame retardant is washed with an alcohol solvent. Then, it is dried at normal pressure until the alcohol solvent is completely evaporated, and finally, a high-flame-retardant, high-strength organosilicon aerogel is obtained. The mass ratio of the aminosilane to the glycidyl ether is (20-80): (40-80); The aminosilane is one or more of 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldimethoxysilane or 3-aminopropylmethyldiethoxysilane; The glycidyl ether is one or more of ethylene glycol diglycidyl ether, resorcinol diglycidyl ether, or diglycidyl ether. The flame retardant is one or more of dimethyl methylphosphonate, diethyl ethyl phosphate, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide or N,N-(2-hydroxyethyl)aminomethyl phosphate. The reaction temperature between the flame retardant and the high-strength organosilicon aerogel is 80℃-150℃, and the reaction time is 12-72h.
2. The method for preparing high flame-retardant, high-strength organosilicon aerogel according to claim 1, characterized in that, In the organosilicon sol, the mass fraction of the solute is 15-60%, the amount of deionized water added is 4-6 times the molar amount of aminosilane, and the amount of catalyst added is 0.5-1% of the total mass.
3. The method for preparing high flame retardant and high-strength organosilicon aerogel according to claim 1, characterized in that, The alcohol solvent is one or more of ethanol, methanol, ethylene glycol or isopropanol; the catalyst is one or more of ammonia, ammonium fluoride or tetramethylammonium hydroxide.
4. The method for preparing high flame retardant and high-strength organosilicon aerogel according to claim 1, characterized in that, The stirring time for complete hydrolysis of aminosilane is 10-30 min, the heating aging temperature is 60-120℃, the time is 12-72 h, and the drying time is 24-72 h.
5. The method for preparing high flame retardant and high-strength organosilicon aerogel according to claim 1, characterized in that, The alcohol solvent used to dissolve the flame retardant and for washing is one or more of ethanol, methanol, ethylene glycol, or isopropanol.
6. A highly flame-retardant, high-strength organosilicon aerogel prepared by the method according to any one of claims 1-5.
7. An application of the high flame-retardant, high-strength organosilicon aerogel as described in claim 6, characterized in that, This aerogel can be applied to building materials, walls, and medium- and low-temperature insulation.