Preparation method of silica aerogel fireproof coating

Abstract

This invention relates to the field of fire-retardant coating technology, specifically a method for preparing a silica aerogel fire-retardant coating, comprising the following steps: S1. Mixing and stirring a modified base emulsion and pentaerythritol to obtain a preliminary mixture; S2. Adding silica aerogel and acrylate emulsion to the preliminary mixture; S3. Stirring the mixture obtained in step S2, discharging and allowing it to stand for curing to obtain the silica aerogel fire-retardant coating. This invention uses high-silica fly ash to replace traditional silicon sources, significantly reducing raw material costs while simultaneously achieving resource utilization of industrial solid waste, aligning with green manufacturing and the circular economy. Through the synergistic design of "fly ash-based aerogel + composite flame-retardant emulsion," the fire-retardant coating achieves lightweight, high-efficiency, and low-cost characteristics, possessing excellent engineering application prospects and market competitiveness.

Description

Technical Field

[0001] This invention relates to the field of fire-retardant coating technology, specifically to a method for preparing a silica aerogel fire-retardant coating. Background Technology

[0002] With the rapid development of industries such as construction, transportation, and power, higher requirements have been placed on fire-resistant and safe materials. Fire-retardant coatings, as an important passive fire protection method, delay the spread of flames and reduce heat transfer, thus buying valuable evacuation and rescue time for structural components. They have become an indispensable functional coating in modern buildings and industrial facilities.

[0003] Traditional fire-retardant coatings often rely on fillers such as aluminum hydroxide, calcium carbonate, and expanded graphite to achieve flame retardancy through physical heat absorption, gas release, or char layer expansion. However, these coatings often have the following limitations: to achieve the ideal fire resistance rating, traditional fillers often need to be added in high proportions, resulting in high coating density and thick application thickness, affecting aesthetics and applicability; under prolonged or extremely high temperatures, ordinary fillers are prone to decomposition and failure, resulting in insufficient strength of the char layer structure and difficulty in maintaining long-term heat insulation; some flame retardants contain halogens and phosphorus, posing environmental and health hazards; and high-performance heat insulation materials (such as aerogels) are difficult to use on a large scale in fire-retardant coatings due to complex preparation processes and high raw material costs.

[0004] Fly ash, a solid waste from coal-fired power plants, is rich in silica and alumina, making it a potential source of silicon and aluminum. In recent years, research on preparing silica aerogels from high-silica fly ash has deepened, offering possibilities for its application in functional materials. If it can be organically combined with coating systems, it can not only achieve high-value utilization of solid waste but also provide a new path for developing lightweight, efficient, and environmentally friendly new fire-retardant coatings. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide a method for preparing silica aerogel fire-retardant coating.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A method for preparing a silica aerogel fire-retardant coating includes the following preparation steps:

[0008] S1. By weight, mix 80-100 parts of modified base emulsion and 40-45 parts of pentaerythritol, and stir at 1300-1500 r / min for 10-15 min to obtain a preliminary mixture;

[0009] S2. Add 3.5-4 parts of silica aerogel that has passed through a 400-mesh sieve and 5-8 parts of acrylate emulsion to the preliminary mixture obtained in step S1;

[0010] S3. Stir the mixture obtained in step S2 at a speed of 2000-2200 r / min for 25-30 min, and let it stand to mature after discharge to obtain silica aerogel fireproof coating.

[0011] The preparation of the modified base emulsion includes the following steps:

[0012] S21. By weight, add 0.5-1 parts of polyethylene glycol octylphenyl ether, 0.5-1 parts of sodium nitrite, and 0.2-0.5 parts of zinc pyridinethione to 50-60 parts of deionized water and stir for 10-15 minutes to obtain a preliminary mixed emulsion.

[0013] S22. Add 45-50 parts of emulsion modifier to the preliminary mixed emulsion obtained in step S21, and stir at a speed of 750-800 r / min for 15-20 min to obtain the secondary mixed emulsion;

[0014] S23. Add 40-50 parts of deionized water to the secondary mixed emulsion obtained in step S22, stir at high speed of 2000-2500 r / min, discharge the material, and finally obtain the modified base emulsion.

[0015] Preferably, the preparation of the emulsion modifier includes the following steps:

[0016] S221. By weight, mix 40-45 parts of pure acrylic emulsion, 0.3-0.5 parts of sodium benzoate, 1-2 parts of sodium polyacrylate, and 0.5-1 parts of sodium hexametaphosphate, and stir at a speed of 400-500 r / min for 10-15 min.

[0017] S222. Add 3-5 parts of ammonium phosphate, 2-4 parts of sodium bicarbonate and 3-4 parts of aluminum hydroxide to the mixture obtained in step S221, and stir at a speed of 800-1000 r / min for 15-20 min.

[0018] S223. Add 1-2 parts of dibutyl phthalate, 0.2-0.5 parts of defoamer and 6-10 parts of deionized water to the mixture obtained in step S222, stir for 10-15 minutes, and pass through a 200-mesh sieve to obtain the emulsion modifier.

[0019] Preferably, the resting and ripening time in step S3 is 1-2 hours.

[0020] Preferably, the stirring speed in step S21 is 450-500 r / min.

[0021] Preferably, the stirring time in step S23 is 15-20 min.

[0022] Preferably, the defoamer is selected from BYK-024.

[0023] Preferably, the stirring speed in step S223 is 1200-1500 r / min.

[0024] Preferably, the preparation of silica aerogel includes the following steps:

[0025] S11. After passing through a 200-mesh sieve, the fly ash is placed in a drying oven at 105℃ and dried for 10-12 hours, and then calcined in a muffle furnace at 750-950℃ for 2-3 hours.

[0026] S12. After acid leaching, the calcined fly ash is filtered. The resulting acid residue is dried and then added to a sodium hydroxide solution with a mass fraction of 5-20%. The residue is alkali-dissolved at 60-100℃ for 2-5 hours and then filtered.

[0027] S13. Place the solution obtained by filtration in step S12 into a drying oven and age it at 60-65℃ for 36-48 hours. Wash it with deionized water 3-4 times to obtain high silica fly ash gel.

[0028] S14. Add an interface modifier to the high-silica fly ash gel and dry it under normal pressure to form a powder to obtain silica aerogel.

[0029] Compared with the prior art, the beneficial effects of the present invention are:

[0030] 1. This invention replaces traditional silicon sources with high-silica fly ash, significantly reducing raw material costs while simultaneously realizing the resource utilization of industrial solid waste, aligning with green manufacturing and the circular economy. Through the synergistic design of "fly ash-based aerogel + composite flame-retardant emulsion," the fire-retardant coating achieves lightweight, high-efficiency, and low-cost characteristics, possessing promising engineering application prospects and market competitiveness.

[0031] 2. This invention utilizes the synergistic effect of emulsion modifiers and modified base emulsions to give the fire-retardant coating a nanoporous structure with extremely low thermal conductivity. This creates a stable heat-insulating layer within the coating, significantly delaying heat transfer to the substrate. Furthermore, it forms a dense and robust carbon-silicon-aluminum composite layer at high temperatures, enhancing the integrity and erosion resistance of the carbon layer. Simultaneously, the stepwise preparation of the emulsion modifier and modified base emulsion achieves high dispersion and compatibility of the functional components, preventing filler sedimentation and agglomeration, and improving the coating's workability and storage stability. Attached Figure Description

[0032] Figure 1 This is a process flow diagram for preparing the silica aerogel fire-retardant coating of the present invention;

[0033] Figure 2 This is a microscopic image of the silica aerogel fire-retardant coating obtained in Example 1 of the present invention, taken at a depth of 1 μm before combustion.

[0034] Figure 3 This is a microscopic image of the silica aerogel fire-retardant coating obtained in Example 2 of the present invention at a depth of 1 μm before combustion;

[0035] Figure 4 This is a microscopic image of the silica aerogel fire-retardant coating obtained in Example 3 of the present invention at a depth of 1 μm before combustion;

[0036] Figure 5 This is a microscopic image of the silica aerogel fire-retardant coating obtained in Example 1 of the present invention at 200 nm after combustion.

[0037] Figure 6 This is a microscopic image of the silica aerogel fire-retardant coating obtained in Example 2 of the present invention at 200 nm after combustion.

[0038] Figure 7 This is a microscopic image of the silica aerogel fire-retardant coating obtained in Example 3 of the present invention at 200 nm after combustion.

[0039] Figure 8 This is a fire resistance limit data analysis chart of the silica aerogel fireproof coating obtained in Example 1 of the present invention;

[0040] Figure 9 The infrared spectra of the silica aerogel fire-retardant coatings obtained in Example 1 and Comparative Examples 3-5 of this invention are shown. Detailed Implementation

[0041] The present invention will now be clearly and completely described in conjunction with embodiments thereof. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0042] Please see Figures 1-9 The present invention provides a technical solution:

[0043] Example 1

[0044] A method for preparing a silica aerogel fire-retardant coating:

[0045] Before preparing the silica aerogel fire-retardant coating, the silica aerogel, emulsion modifier, and modified base emulsion are prepared first:

[0046] The preparation of silica aerogel includes the following steps:

[0047] Before preparing silica aerogel, a crosslinking modification liquid and an interface modifier are first prepared:

[0048] The preparation of the crosslinking modified liquid includes the following steps:

[0049] S1321. Dissolve 5g sodium stearate and 10g dodecyl betaine in 80ml anhydrous ethanol in a 60℃ water bath and stir at 300r / min for 20min to obtain a transparent solution.

[0050] S1322. Add 170g of trimethylchlorosilane and 180ml of anhydrous ethanol to the reaction vessel, and stir at 300r / min for 20min under a nitrogen atmosphere. During stirring, slowly add the transparent solution obtained in step S1321.

[0051] S1323. Add 30g of sodium lignosulfonate to the mixture obtained in step S1322, heat to 50℃ and react for 1.5h, then cool to room temperature and filter to obtain the crosslinked modified liquid;

[0052] The preparation of interface modifiers includes the following steps:

[0053] S131. Add 5g of lecithin and 5g of trisodium citrate to 800ml of anhydrous ethanol and ultrasonically disperse at 40℃ for 20min;

[0054] S132. Slowly add 230g of crosslinking modification liquid to the mixed solution obtained in step S131 while stirring at a speed of 200r / min, and maintain the temperature at 40℃ for 30min to obtain the primary modifier.

[0055] S133. Add 350g of n-hexane to the primary modifier and continue stirring at 200r / min for 15min to obtain the interface modifier.

[0056] S11. After passing through a 200-mesh sieve, the fly ash is placed in a drying oven at 105℃ and dried for 10 hours, then calcined in a muffle furnace at 750℃ for 2 hours.

[0057] S12. 100g of calcined fly ash was treated with 600ml of 2mol / L hydrochloric acid solution for acid leaching at 60℃ for 1h. After filtration, the acid residue was dried and then added to 800ml of 5% sodium hydroxide solution for alkaline dissolution at 60℃ for 2h. After filtration, the residue was filtered again.

[0058] S13. The solution obtained by filtration in step S12 is placed in a drying oven and aged at 60°C for 36 hours. It is then washed three times with deionized water to obtain high silica fly ash gel.

[0059] S14. Add an interface modifier with a mass of 0.3 times that of the gel to the high silica fly ash gel, and dry it at normal pressure by first drying at 60℃ for 2 hours, then at 90℃ for 2 hours, and finally at 120℃ for 1 hour to form a powder, thus obtaining silica aerogel.

[0060] The preparation of emulsion modifiers includes the following steps:

[0061] S221. Mix 40g of pure acrylic emulsion, 0.3g of sodium benzoate, 1g of sodium polyacrylate, and 0.5g of sodium hexametaphosphate, and stir at 400r / min for 10min;

[0062] S222. Add 3g of ammonium phosphate, 2g of sodium bicarbonate and 3g of aluminum hydroxide to the mixture obtained in step S221, and stir at 800r / min for 15min;

[0063] S223. Add 1g of dibutyl phthalate, 0.2g of defoamer (BYK-024) and 6g of deionized water to the mixture obtained in step S222, stir at 1200r / min for 10min, and pass through a 200-mesh sieve to obtain the emulsion modifier.

[0064] The preparation of the modified base emulsion includes the following steps:

[0065] S21. Add 0.5g polyethylene glycol octylphenyl ether, 0.5g sodium nitrite, and 0.2g zinc pyridinethione to 50g deionized water and stir at 450r / min for 10min to obtain a preliminary mixed emulsion.

[0066] S22. Add 45g of modified emulsion to the preliminary mixed emulsion obtained in step S21, and stir at 750r / min for 15min to obtain the secondary mixed emulsion;

[0067] S23. Add 40g of deionized water to the secondary mixed emulsion obtained in step S22, stir at 2000r / min for 15min, discharge the material, and finally obtain the modified base emulsion.

[0068] S1. Mix 80g of modified base emulsion and 40g of pentaerythritol, and stir at 1300r / min for 10min to obtain a preliminary mixture;

[0069] S2. Add 3.86g of silica aerogel that has passed through a 400-mesh sieve and 5g of acrylic emulsion to the preliminary mixture obtained in step S1;

[0070] S3. Stir the mixture obtained in step S2 at a speed of 2000 r / min for 25 min, and let it stand for 1 h after discharge to obtain a silica aerogel fireproof coating, wherein the content of silica aerogel is 3%.

[0071] Example 2

[0072] A method for preparing a silica aerogel fire-retardant coating:

[0073] Before preparing the silica aerogel fire-retardant coating, the silica aerogel, emulsion modifier, and modified base emulsion are prepared first:

[0074] The preparation method of silica aerogel is the same as that in Example 1.

[0075] The preparation of emulsion modifiers includes the following steps:

[0076] S221. Mix 45g of pure acrylic emulsion, 0.5g of sodium benzoate, 2g of sodium polyacrylate and 1g of sodium hexametaphosphate, and stir at 500r / min for 15min.

[0077] S222. Add 5g of ammonium phosphate, 4g of sodium bicarbonate and 4g of aluminum hydroxide to the mixture obtained in step S221, and stir at 1000r / min for 20min.

[0078] S223. Add 2g of dibutyl phthalate, 0.5g of defoamer (BYK-024) and 10g of deionized water to the mixture obtained in step S222, stir at 1500r / min for 15min, and pass through a 200-mesh sieve to obtain the emulsion modifier.

[0079] The preparation of the modified base emulsion includes the following steps:

[0080] S21. Add 1g of polyethylene glycol octylphenyl ether, 1g of sodium nitrite, and 0.5g of zinc pyridinethione to 60g of deionized water, and stir at 500r / min for 15min to obtain a preliminary mixed emulsion.

[0081] S22. Add 50g of modified emulsion to the preliminary mixed emulsion obtained in step S21, and stir at 800r / min for 20min to obtain the second-step mixed emulsion;

[0082] S23. Add 50g of deionized water to the secondary mixed emulsion obtained in step S22, stir at 2500r / min for 20min, discharge the material, and finally obtain the modified base emulsion.

[0083] S1. Mix 100g of modified base emulsion and 45g of pentaerythritol, and stir at 1500r / min for 15min to obtain a preliminary mixture;

[0084] S2. Add 3.5g of silica aerogel that has passed through a 400-mesh sieve and 8g of acrylic emulsion to the preliminary mixture obtained in step S1;

[0085] S3. Stir the mixture obtained in step S2 at a speed of 2200 r / min for 30 min, and let it stand for 2 hours after discharge to obtain silica aerogel fireproof coating.

[0086] Example 3

[0087] A method for preparing a silica aerogel fire-retardant coating:

[0088] Before preparing the silica aerogel fire-retardant coating, the silica aerogel, emulsion modifier, and modified base emulsion are prepared first:

[0089] The preparation method of silica aerogel is the same as that in Example 1.

[0090] The preparation of emulsion modifiers includes the following steps:

[0091] S221. Mix 42g of pure acrylic emulsion, 0.4g of sodium benzoate, 1.5g of sodium polyacrylate and 0.8g of sodium hexametaphosphate, and stir at 450r / min for 13min.

[0092] S222. Add 4g of ammonium phosphate, 3g of sodium bicarbonate and 3.5g of aluminum hydroxide to the mixture obtained in step S221, and stir at 900r / min for 17min;

[0093] S223. Add 1.5g of dibutyl phthalate, 0.3g of defoamer (BYK-024) and 8g of deionized water to the mixture obtained in step S222, stir at 1300r / min for 14min, and pass through a 200-mesh sieve to obtain the emulsion modifier.

[0094] The preparation of the modified base emulsion includes the following steps:

[0095] S21. Add 0.8g polyethylene glycol octylphenyl ether, 0.8g sodium nitrite, and 0.4g zinc pyridinethione to 55g deionized water and stir at 480r / min for 14min to obtain a preliminary mixed emulsion.

[0096] S22. Add 48g of modified emulsion to the preliminary mixed emulsion obtained in step S21, and stir at 780r / min for 18min to obtain the secondary mixed emulsion;

[0097] S23. Add 45g of deionized water to the secondary mixed emulsion obtained in step S22, stir at 2400r / min for 18min, discharge the material, and finally obtain the modified base emulsion.

[0098] S1. Mix 90g of modified base emulsion and 42g of pentaerythritol, and stir at 1400r / min for 14min to obtain a preliminary mixture;

[0099] S2. Add 4g of silica aerogel that has passed through a 400-mesh sieve and 6g of acrylate emulsion to the preliminary mixture obtained in step S1;

[0100] S3. Stir the mixture obtained in step S2 at a speed of 2100 r / min for 28 min, and let it stand for 1.5 h after discharge to obtain silica aerogel fireproof coating.

[0101] Comparative Example 1

[0102] The only difference between Comparative Example 1 and Example 1 is that no emulsion modifier was added in this comparative example; the other steps are exactly the same in Comparative Example 1 and Example 1.

[0103] Comparative Example 2

[0104] The only difference between Comparative Example 2 and Example 1 is that the modified base emulsion in this comparative example is replaced with a mixture of pure acrylic emulsion and pentaerythritol in a mass ratio of 1:1. The remaining steps are exactly the same in Comparative Example 2 and Example 1.

[0105] Comparative Example 3

[0106] The only difference between Comparative Example 3 and Example 1 is that the content of silica aerogel in this comparative example is controlled at 1%, while the other steps are exactly the same in Comparative Example 3 and Example 1.

[0107] Comparative Example 4

[0108] The only difference between Comparative Example 4 and Example 1 is that the content of silica aerogel in this comparative example is controlled at 2%, while the other steps are exactly the same in Comparative Example 4 and Example 1.

[0109] Comparative Example 5

[0110] The only difference between Comparative Example 5 and Example 1 is that the content of silica aerogel in this comparative example is controlled at 4%, while the other steps are exactly the same in Comparative Example 5 and Example 1.

[0111] Performance testing:

[0112] After degreasing, derusting, and anti-corrosion treatment, the steel plate substrates were coated with the silica aerogel fire-retardant coatings obtained in Examples 1-3 and Comparative Examples 1-2, respectively, with the dry film thickness controlled at 2 mm. The coatings were then allowed to air dry for 7 days at room temperature (25℃) and relative humidity (50%). Fire resistance and thermal insulation performance were tested according to GB / T 9978.1-2008 "Test Methods for Fire Resistance of Building Components". The thermal insulation performance data are shown in Table 1 below.

[0113] Table 1 Thermal insulation performance data

[0114]

[0115] According to the data in Table 1, the silica aerogel fireproof coatings obtained in Examples 1-3 are significantly better than the comparative examples in terms of heat insulation performance. This indicates that the emulsion modifier and the modified base emulsion work synergistically to build a stable heat insulation layer in the coating, significantly delaying the transfer of heat to the substrate and effectively improving the overall heat insulation performance of the material.

[0116] Appendix Figure 2-4 These are microscopic images of the silica aerogel fire-retardant coatings obtained in Examples 1-3 of this invention before combustion; (See attached images.) Figure 5-7 The images shown are microscopic images of the silica aerogel fire-retardant coatings obtained in Examples 1-3 of this invention after combustion. A comparison of the silica aerogel fire-retardant coatings before and after combustion reveals that the fire-retardant coating crystals remain intact, and the aerogel particles show no significant changes, demonstrating strong fire-retardant performance.

[0117] Appendix Figure 8 This is a data analysis graph of the fire resistance limit of the silica aerogel fire-retardant coating obtained in Example 1 of this invention. The graph shows that the initial temperature stabilizes slightly (approximately 30-40°C), then rises rapidly, jumping from about 40°C to over 250°C in about 10 minutes. This indicates that the coating absorbs heat and begins to exert its insulating effect in a short time, but the initial temperature rise rate is relatively fast. After 10 minutes, the temperature rise rate slows significantly, gradually increasing from 250°C to about 320°C (at 60 minutes), and the curve gradually flattens out. This demonstrates the insulating performance of the fire-retardant coating. As time progresses, a fire-retardant layer (such as an intumescent insulating layer) gradually forms, hindering heat transfer to the steel structure and reducing the rate of temperature rise.

[0118] Appendix Figure 9 The infrared spectra of the silica aerogel fire-retardant coatings obtained in Example 1 and Comparative Examples 3-5 of this invention are shown. In Comparative Examples 3-5, the silica aerogel content was 1%, 2%, and 4%, respectively, while in Example 1, the silica aerogel content was 3%. The figures show that the positions of the four content characteristic peaks remained essentially unchanged, but the peak intensities were affected by the aerogel, indicating that it has a regulatory effect on the sample structure and composition. (2344 cm⁻¹) -1 The peak at 1439 cm⁻¹ represents the C=O stretching vibration caused by CO₂ adsorption in the air, and its variation is not obvious. -1 and 720 cm -1 CO3 2- The characteristic peak intensity decreases with increasing aerogel content, and the transmittance of the reaction sample decreases. This is attributed to the aerogel promoting the reaction between CaO and CO2, altering the calcium carbonate content and crystallinity. This trend tends to level off after the content reaches ≥2%. (1092 cm⁻¹) -1 1102cm -1and 870cm -1 The peak at this point is a characteristic peak of Si-O. When the content reaches 3%, the peak intensity and peak width increase and shift, proving that the aerogel has been successfully introduced.

[0119] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a silica aerogel fireproof coating, characterized by, The preparation steps include the following: S1. By weight, mix 80-100 parts of modified base emulsion and 40-45 parts of pentaerythritol, and stir at 1300-1500 r / min for 10-15 min to obtain a preliminary mixture; S2. Add 3.5-4 parts of silica aerogel that has passed through a 400-mesh sieve and 5-8 parts of acrylate emulsion to the preliminary mixture obtained in step S1; S3. Stir the mixture obtained in step S2 at a speed of 2000-2200 r / min for 25-30 min, and let it stand to mature after discharge to obtain silica aerogel fireproof coating. The preparation of the modified base emulsion includes the following steps: S21. By weight, add 0.5-1 parts of polyethylene glycol octylphenyl ether, 0.5-1 parts of sodium nitrite, and 0.2-0.5 parts of zinc pyridinethione to 50-60 parts of deionized water and stir for 10-15 minutes to obtain a preliminary mixed emulsion. S22. Add 45-50 parts of emulsion modifier to the preliminary mixed emulsion obtained in step S21, and stir at a speed of 750-800 r / min for 15-20 min to obtain the secondary mixed emulsion; S23. Add 40-50 parts of deionized water to the secondary mixed emulsion obtained in step S22, stir at high speed of 2000-2500 r / min, discharge the material, and finally obtain the modified base emulsion. The preparation of the emulsion modifier includes the following steps: S221. By weight, mix 40-45 parts of pure acrylic emulsion, 0.3-0.5 parts of sodium benzoate, 1-2 parts of sodium polyacrylate, and 0.5-1 parts of sodium hexametaphosphate, and stir at a speed of 400-500 r / min for 10-15 min. S222. Add 3-5 parts of ammonium phosphate, 2-4 parts of sodium bicarbonate and 3-4 parts of aluminum hydroxide to the mixture obtained in step S221, and stir at a speed of 800-1000 r / min for 15-20 min. S223. Add 1-2 parts of dibutyl phthalate, 0.2-0.5 parts of defoamer and 6-10 parts of deionized water to the mixture obtained in step S222, stir for 10-15 minutes, and pass through a 200-mesh sieve to obtain the emulsion modifier. The defoamer is selected from BYK-024; The preparation of the silica aerogel includes the following steps: S11. After passing through a 200-mesh sieve, the fly ash is placed in a drying oven at 105℃ and dried for 10-12 hours, and then calcined in a muffle furnace at 750-950℃ for 2-3 hours. S12. After acid leaching, the calcined fly ash is filtered. The resulting acid residue is dried and then added to a sodium hydroxide solution with a mass fraction of 5-20%. The residue is alkali-dissolved at 60-100℃ for 2-5 hours and then filtered. S13. Place the solution obtained by filtration in step S12 into a drying oven and age it at 60-65℃ for 36-48 hours. Wash it with deionized water 3-4 times to obtain high silica fly ash gel. S14. Add an interface modifier to the high-silica fly ash gel and dry it under normal pressure to form a powder to obtain silica aerogel.

2. The method for preparing a silica aerogel fire-retardant coating according to claim 1, characterized in that, The resting and ripening time in step S3 is 1-2 hours.

3. The method for preparing a silica aerogel fire-retardant coating according to claim 1, characterized in that, The stirring speed in step S21 is 450-500 r / min.

4. The method for preparing a silica aerogel fire-retardant coating according to claim 1, characterized in that, The stirring time in step S23 is 15-20 min.

5. The method for preparing a silica aerogel fire-retardant coating according to claim 1, characterized in that, The stirring speed in step S223 is 1200-1500 r / min.

Images