Nano-silicon glass inorganic fireproof liquid and preparation method thereof

Abstract

This application relates to the field of fire retardants, and in particular to a nano-silica glass inorganic fire retardant liquid and its preparation method. The nano-silica glass inorganic fire retardant liquid, by weight, comprises the following raw materials: 100-130 parts deionized water, 45-60 parts potassium hydroxide, 60-75 parts quartz sand, 130-170 parts silica sol, 0.6-1.2 parts defoamer, 6-10 parts glycerol, 1-2 parts wetting and dispersing agent, 0.1-0.3 parts preservative, 3-5 parts antifreeze, and 9-15 parts combined functional agent. The nano-silica glass inorganic fire retardant liquid prepared in this application solves the technical problems of large batch-to-batch modulus fluctuations, easy gelation, and reduced fire retardant performance in existing technologies. It has a suitable modulus, stable solid content, good fluidity, high fire retardant efficiency, and excellent long-term storage stability without gelation. It solves technical problems in the field and provides a new approach to improving the overall performance of fire retardant liquids.

Description

Technical Field

[0001] This application relates to the field of fire retardants, and in particular to a nano-silicon glass inorganic fire retardant liquid and its preparation method. Background Technology

[0002] Currently, inorganic fire retardants for glass are mainly prepared through chemical synthesis and are widely used on glass surfaces in construction, transportation, and fire protection to improve the fire resistance of glass in high-temperature environments. Existing inorganic fire retardants are mostly based on silicate systems, such as using sodium silicate or potassium silicate as film-forming substances, combined with water and additives to form a transparent coating. When exposed to fire, this coating forms a dense silicate insulating layer, thus delaying glass breakage and flame spread. However, traditional silicate fire retardants often suffer from problems during preparation, including unstable modulus control, high impurity ion content, and poor product storage stability. This leads to issues in practical applications such as easy moisture absorption, whitening, crystallization, or significant degradation of fire resistance at high temperatures. With increasing industry demands for glass fire safety performance, there is an urgent need to develop a high-purity, highly stable nano-silica glass inorganic fire retardant with excellent fluidity and film-forming properties.

[0003] To address existing needs, current technologies attempt to optimize the performance of fire retardant liquids by introducing silica sol, adjusting the alkaline system, and adding additives. For example, using potassium hydroxide reacted with quartz sand to generate potassium silicate solution as the base film-forming material, and then compounding it with silica sol of different particle sizes, allows for adjustment of the product's molar ratio and solid content. Simultaneously, the introduction of additives such as glycerol improves the coating's flowability and crack resistance. The appropriate addition of defoamers also helps reduce bubble defects and improve coating quality. Nevertheless, existing preparation methods still face numerous technical bottlenecks in practical operation.

[0004] First, the synthesis conditions for potassium silicate solution are demanding, requiring a reaction temperature controlled at around 170℃ and precise pressure control, leading to significant batch-to-batch modulus fluctuations. An excessively high modulus can cause gelation, while a low modulus reduces fire-retardant performance. Second, improper addition of silica sol and temperature control, especially the initial addition of large-particle silica sol, can cause localized gelation or uneven reaction if the rate is too rapid or the temperature deviates from approximately 80℃, affecting the transparency and stability of the final product. Residue can also accelerate coating aging or generate harmful byproducts at high temperatures. These technical issues hinder the performance improvement and large-scale application of existing inorganic glass fire-retardant liquids. Summary of the Invention

[0005] In summary, optimizing the synthesis and subsequent compounding process of potassium silicate solution to obtain a nano-silica glass inorganic fire retardant liquid with suitable modulus, stable solid content, good fluidity, and no gelation during long-term storage, while ensuring high-purity raw materials and strictly controlling reaction conditions, has become a key technical challenge that urgently needs to be solved in this field.

[0006] To address the above problems, this application provides the following technical solution:

[0007] The first aspect of this application provides a nano-silica glass inorganic fire retardant liquid, the raw material scheme of which, by weight, includes: 100-130 parts of deionized water, 45-60 parts of potassium hydroxide, 60-75 parts of quartz sand, 130-170 parts of silica sol, 0.6-1.2 parts of defoamer, 6-10 parts of glycerol, 1-2 parts of wetting and dispersing agent, 0.1-0.3 parts of preservative, 3-5 parts of antifreeze, and 9-15 parts of combined functional agent.

[0008] Preferably, the potassium hydroxide has a purity of ≥99.5%.

[0009] Preferably, the mass ratio of potassium hydroxide, quartz sand and silica sol is (48~55):(62~70):(135~160).

[0010] More preferably, the mass ratio of potassium hydroxide, quartz sand and silica sol is (50~53):(65~68):(140~150).

[0011] Preferably, the quartz sand is high-purity quartz sand.

[0012] Preferably, the high-purity quartz sand has a SiO2 content of ≥99.5%.

[0013] More preferably, the high-purity quartz sand has a SiO2 content of ≥99.8%.

[0014] Preferably, the high-purity quartz sand has an average mesh size of 300-600 mesh.

[0015] More preferably, the high-purity quartz sand has an average mesh size of 400-600 mesh.

[0016] Preferably, the solid content of the silica sol is 30-40%.

[0017] Preferably, the silica sol is a combination of large-particle-size silica sol and small-particle-size silica sol.

[0018] Preferably, the mass ratio of the large-particle-size silica sol to the small-particle-size silica sol is (8.5~10.5):(4.5~6).

[0019] More preferably, the mass ratio of the large-particle-size silica sol to the small-particle-size silica sol is (9~10):(5~5.5).

[0020] Preferably, the average particle size of the large-particle-size silica sol is 50~100nm.

[0021] More preferably, the average particle size of the large-particle-size silica sol is 50~70nm.

[0022] Preferably, the average particle size of the small-particle-size silica sol is 10~30nm.

[0023] More preferably, the average particle size of the small-particle-size silica sol is 10~20nm.

[0024] Preferably, the defoamer is at least one of modified silicone defoamers.

[0025] More preferably, the defoamer is FoamStar SI 2210 or FoamStar ED 2528.

[0026] More preferably, the defoamer is FoamStar ED 2528, manufactured by BASF, Germany.

[0027] The combination of large-particle-size silica sol and small-particle-size silica sol with defoamer in this application optimizes particle packing through the synergistic effect of particle size gradient, forming a dense silica-oxygen network and improving fire resistance and stability. The stepwise addition of defoamer, in conjunction with the gradient addition of silica sol, effectively suppresses microbubbles generated by the mixing of high-solids materials, avoids structural defects caused by residual bubbles, ensures product flowability and long-term storage stability, and prevents gelation.

[0028] Preferably, the mass ratio of potassium hydroxide, glycerol and the combined functional agent is (48~55):(8~10):(11~14).

[0029] More preferably, the mass ratio of potassium hydroxide, glycerol and the combined functional agent is (50~53):(8~9):(12~13).

[0030] Preferably, the wetting and dispersing agent is sodium polyacrylate or ammonium polyacrylate.

[0031] Preferably, the wetting and dispersing agent is sodium polyacrylate.

[0032] Preferably, the preservative is isothiazolinone or benzisothiazolinone.

[0033] Preferably, the preservative is benzisothiazolinone.

[0034] Preferably, the antifreeze is a combination of ethylene glycol and propylene glycol.

[0035] Preferably, the mass ratio of ethylene glycol to propylene glycol is (1~2):(1~2).

[0036] Preferably, the mass ratio of ethylene glycol to propylene glycol is 1:1.

[0037] Preferably, the combined functional agent is a combination of boric acid, aluminum dihydrogen phosphate, and calcium formate.

[0038] Preferably, the mass ratio of boric acid, aluminum dihydrogen phosphate and calcium formate is (3~5):(4~6):(2~3).

[0039] More preferably, the mass ratio of boric acid, aluminum dihydrogen phosphate and calcium formate is (3~4):(5~6):(2.3~2.6).

[0040] In existing technologies, fire retardant liquids rely solely on the potassium silicate-silica sol system, which lacks sufficient water resistance and high-temperature strength. However, the functional composition of boric acid, aluminum dihydrogen phosphate, and calcium formate added in this application forms a boron-phosphorus-silica hybrid structure with the silicon-oxygen network at high temperatures, significantly reducing the moisture absorption of the coating. Furthermore, the high-temperature products of calcium formate react with the silica sol to form a gel, filling micropores and improving adhesion strength. The combined effect of these three components significantly enhances the fire resistance limit of the fire retardant liquid while maintaining superior storage stability.

[0041] The second aspect of this application provides a method for preparing the above-mentioned nano-silicon glass inorganic fire retardant liquid, specifically including the following steps:

[0042] S1: Add deionized water, potassium hydroxide and quartz sand to the reactor according to the ratio, start stirring to gradually raise the temperature to 80°C, keep it at the temperature and continue to raise the temperature to 170~175°C while introducing nitrogen into the reactor to stabilize the pressure, and filter the reaction liquid to obtain potassium silicate solution.

[0043] S2: Transfer the potassium silicate solution to a mixing vessel equipped with heating and stirring. Heat and maintain the temperature of the solution in the vessel at 78~82℃. Add large-particle silica sol at a rate of 8~10 parts / min while stirring, and add some defoamer at the same time. After the addition is complete, continue stirring. Then add small-particle silica sol and the remaining defoamer at the same rate. After that, add glycerol and wetting and dispersing agent and stir evenly.

[0044] S3: Add the combined functional agent, preservative and antifreeze in sequence, stirring until completely mixed after each addition. Then let it cool naturally and stand to defoam. The finished product is ready.

[0045] Preferably, the preparation method of the nano-silica glass inorganic fire retardant liquid specifically includes the following steps:

[0046] S1: Add deionized water, potassium hydroxide and quartz sand to a stainless steel reactor according to the specified ratio, start stirring at 250~350 rpm, heat to 80℃ at a rate of 1.5~2℃ / min, hold for 30~35 min, then continue heating to 170~175℃ while introducing nitrogen into the reactor to stabilize the pressure at 0.5MPa, and react at constant temperature and pressure for 6~8 h. After the reaction is completed, allow it to cool naturally to below 60℃, and send the reaction solution to a plate and frame filter press for filtration to obtain potassium silicate solution.

[0047] S2: Transfer the potassium silicate solution to a mixing vessel equipped with heating and stirring. Heat and maintain the temperature of the solution in the vessel at 78~82℃. Add large-particle silica sol at a rate of 8~10 parts / min under stirring at 150~200 rpm, and simultaneously add 60~70wt% of defoamer. After the addition is complete, continue stirring for 20~30 min. Then add small-particle silica sol and the remaining defoamer at the same rate, and continue stirring for 15~20 min. After that, add glycerol and wetting and dispersing agent and stir for 10~15 min until homogeneous.

[0048] S3: Control the temperature at 50~55℃ and add the combined functional agent, preservative and antifreeze in sequence. After each addition, stir at 100~150rpm for 15~20min until completely mixed. Then let it cool naturally and stand for 30~40min to defoam. The result is then ready.

[0049] Preferably, the modulus of the potassium silicate solution is 3.5 to 4.

[0050] More preferably, the modulus of the potassium silicate solution is 3.6 to 3.8.

[0051] In the above preparation method, compared with the traditional method of directly heating to 170℃ for reaction, which is prone to local overheating and modulus fluctuation, this application adds an 80℃ heat preservation pre-reaction step before heating to 170℃, so that potassium hydroxide and quartz sand first form low modulus potassium silicate and fix the modulus selection scheme, and then further polymerize by heating and pressurizing, which greatly improves the batch stability of the modulus of the final potassium silicate liquid, solves the technical problems of easy gelation when the modulus is too high and poor performance when the modulus is too low, and provides a foundation for improving the comprehensive performance of fire retardant liquid.

[0052] The beneficial effects and application advantages of this application are as follows:

[0053] 1. The nano-silica glass inorganic fire retardant liquid prepared in this application solves the technical problems of large batch-to-batch modulus fluctuations, which easily cause gelation and reduce fire retardant performance. It has a suitable modulus, stable solid content, good fluidity, high fire retardant efficiency, and excellent stability without gelation during long-term storage. It solves the technical problems in the field and provides a new idea to improve the comprehensive performance of fire retardant liquid.

[0054] 2. The functional composition of boric acid, aluminum dihydrogen phosphate and calcium formate added in this application forms a boron-phosphorus-silicon hybrid structure with the silicon-oxygen network at high temperature, which significantly reduces the moisture absorption of the coating. In addition, the high-temperature product of calcium formate reacts with silica sol to generate a gel material, which fills the micropores and improves the bonding strength. The combined effect of the three significantly improves the fire resistance limit of the fire retardant liquid while maintaining better storage stability.

[0055] 3. This application adds an 80°C heat preservation pre-reaction step before heating to 170°C, so that potassium hydroxide and quartz sand first form low-modulus potassium silicate and fix the selection scheme of modulus. Then, the temperature is raised and pressure is increased for further polymerization, which greatly improves the batch stability of the final potassium silicate liquid modulus and solves the technical problems of easy gelation when the modulus is too high and poor performance when the modulus is too low, thus providing a basis for improving the comprehensive performance of fire retardant liquid. Detailed Implementation

[0056] In the following specific embodiments, unless otherwise specified, the sources / preparation methods of some raw materials are as follows:

[0057] Example 1

[0058] A nano-silica glass inorganic fire retardant liquid, by weight, comprises the following raw materials: 112.5 parts deionized water, 52 parts potassium hydroxide, 66.5 parts quartz sand, 144 parts silica sol, 0.8 parts defoamer, 8.2 parts glycerol, 1.3 parts wetting and dispersing agent, 0.2 parts preservative, 3.8 parts antifreeze, and 12.6 parts combined functional agent.

[0059] The potassium hydroxide has a purity of 99.6%; the quartz sand is high-purity quartz sand with a SiO2 content of 99.8% and an average mesh size of 500 mesh.

[0060] The solid content of the silica sol is 30%; the silica sol is a combination of large-particle-size silica sol and small-particle-size silica sol, with a mass ratio of 9.5:5.5; the average particle size of the large-particle-size silica sol is 60 nm, and the average particle size of the small-particle-size silica sol is 15 nm.

[0061] The defoamer is FoamStar ED 2528, manufactured by BASF, Germany; the wetting and dispersing agent is sodium polyacrylate, industrial grade, manufactured by Shandong Hongquan Chemical Co., Ltd., China; the preservative is benzisothiazolinone; and the antifreeze is a combination of ethylene glycol and propylene glycol in a mass ratio of 1:1.

[0062] The combined functional agent is a combination of boric acid, aluminum dihydrogen phosphate and calcium formate, in a mass ratio of 3.5:6:2.5.

[0063] A method for preparing the above-mentioned nano-silica glass inorganic fire retardant liquid specifically includes the following steps: S1: Deionized water, potassium hydroxide, and quartz sand are added to a stainless steel reactor according to the specified ratio. Stirring is started at 300 rpm, and the temperature is raised to 80°C at a rate of 1.5°C / min. The temperature is maintained for 30 min, and then the temperature is raised to 170°C while nitrogen gas is introduced into the reactor to stabilize the pressure at 0.5 MPa. The reaction is carried out at constant temperature and pressure for 8 h. After the reaction is completed, the temperature is naturally cooled to below 60°C, and the reaction solution is sent to a plate and frame filter press for filtration to obtain potassium silicate solution; S2: The potassium silicate solution is transferred to a mixing vessel equipped with heating and stirring, and the solution in the vessel is heated and maintained. At a temperature range of 78~82℃, large-particle silica sol is added at a rate of 8 parts / min under stirring at 200 rpm, along with 65 wt% of defoamer. After the addition is complete, stirring continues for 25 min. Then, small-particle silica sol and the remaining defoamer are added at the same rate, and stirring continues for 20 min. After that, glycerol and wetting and dispersing agent are added and stirred evenly for 10~15 min. S3: The combined functional agent, preservative and antifreeze are added sequentially at a controlled temperature of 50℃. Each time it is added, it is stirred at 120 rpm for 15 min until it is completely mixed. Then, it is allowed to cool naturally and stand for 30 min to defoam. The result is then obtained.

[0064] The modulus of potassium silicate solution is 3.8.

[0065] Example 2

[0066] A nano-silica glass inorganic fire retardant liquid, by weight, comprises the following raw materials: 112.5 parts deionized water, 55 parts potassium hydroxide, 66.5 parts quartz sand, 144 parts silica sol, 0.8 parts defoamer, 9.5 parts glycerol, 1.3 parts wetting and dispersing agent, 0.2 parts preservative, 3.8 parts antifreeze, and 11.2 parts combined functional agent.

[0067] The above are the only differences between this embodiment and Embodiment 1; all other aspects are the same.

[0068] Example 3

[0069] A nano-silica glass inorganic fire retardant liquid, by weight, comprises the following raw materials: 112.5 parts deionized water, 55 parts potassium hydroxide, 70 parts quartz sand, 138 parts silica sol, 0.8 parts defoamer, 8.2 parts glycerol, 1.3 parts wetting and dispersing agent, 0.2 parts preservative, 3.8 parts antifreeze, and 12.6 parts combined functional agent.

[0070] The above are the only differences between this embodiment and Embodiment 1; all other aspects are the same.

[0071] Comparative Example 1

[0072] A nano-silica glass inorganic fire retardant liquid, by weight, comprises the following raw materials: 112.5 parts deionized water, 60 parts potassium hydroxide, 66.5 parts quartz sand, 144 parts silica sol, 0.8 parts defoamer, 9.8 parts glycerol, 1.3 parts wetting and dispersing agent, 0.2 parts preservative, 3.8 parts antifreeze, and 5.5 parts combined functional agent.

[0073] The above are the only differences between this comparative example and Example 1; all other aspects are the same.

[0074] Comparative Example 2

[0075] A nano-silica glass inorganic fire retardant liquid, by weight, comprises the following raw materials: 112.5 parts deionized water, 52 parts potassium hydroxide, 66.5 parts quartz sand, 144 parts silica sol, 0.8 parts defoamer, 8.2 parts glycerol, 1.3 parts wetting and dispersing agent, 0.2 parts preservative, 3.8 parts antifreeze, and 12.6 parts combined functional agent.

[0076] The silica sol has a solid content of 38%; it is a combination of large-particle-size silica sol and small-particle-size silica sol with a mass ratio of 13.5:1.5; the average particle size of the large-particle-size silica sol is 120 nm, and the average particle size of the small-particle-size silica sol is 40 nm.

[0077] The above are the only differences between this comparative example and Example 1; all other aspects are the same.

[0078] Comparative Example 3

[0079] A nano-silica glass inorganic fire retardant liquid, by weight, comprises the following raw materials: 112.5 parts deionized water, 52 parts potassium hydroxide, 66.5 parts quartz sand, 144 parts silica sol, 0.8 parts defoamer, 8.2 parts glycerol, 1.3 parts wetting and dispersing agent, 0.2 parts preservative, 3.8 parts antifreeze, and 12.6 parts combined functional agent.

[0080] The combined functional agent is a combination of boric acid, aluminum dihydrogen phosphate and calcium formate, with a mass ratio of 8:3:1.

[0081] The above are the only differences between this comparative example and Example 1; all other aspects are the same.

[0082] Comparative Example 4

[0083] A nano-silica glass inorganic fire retardant liquid, by weight, comprises the following raw materials: 112.5 parts deionized water, 52 parts potassium hydroxide, 66.5 parts quartz sand, 144 parts silica sol, 0.8 parts defoamer, 8.2 parts glycerol, 1.3 parts wetting and dispersing agent, 0.2 parts preservative, 3.8 parts antifreeze, and 12.6 parts combined functional agent.

[0084] The combined functional agent is a combination of boric acid, aluminum dihydrogen phosphate and calcium formate, with a mass ratio of 1:6.5:4.5.

[0085] The above are the only differences between this comparative example and Example 1; all other aspects are the same.

[0086] Comparative Example 5

[0087] A nano-silica glass inorganic fire retardant liquid, by weight, comprises the following raw materials: 112.5 parts deionized water, 65 parts potassium hydroxide, 70 parts quartz sand, 180 parts silica sol, 0.8 parts defoamer, 8.2 parts glycerol, 1.3 parts wetting and dispersing agent, 0.2 parts preservative, 3.8 parts antifreeze, and 16.5 parts combined functional agent.

[0088] The preparation method of nano-silica glass inorganic fire retardant liquid includes the following steps: S1: Deionized water, potassium hydroxide and quartz sand are added to a stainless steel reactor according to the specified ratio. The temperature is raised to 170℃ while nitrogen gas is introduced into the reactor to stabilize the pressure at 0.5MPa. The reaction is carried out at constant temperature and pressure for 8 hours. After the reaction is completed, the mixture is naturally cooled to below 60℃. The reaction solution is then sent to a plate and frame filter press for filtration to obtain potassium silicate solution; S2: The potassium silicate solution is transferred to a mixing vessel equipped with heating and stirring. The temperature of the solution in the vessel is heated and maintained within the range of 78~82℃. Under stirring at 200rpm, silica sol and defoamer are added and stirred for 20 minutes. Then, glycerol and wetting and dispersing agent are added and stirred evenly for 10~15 minutes; S3: The combined functional agent, preservative and antifreeze are added sequentially at a controlled temperature of 50℃. Each addition is stirred at 120rpm for 15 minutes until completely mixed. After that, the mixture is allowed to cool naturally and stand for 30 minutes to defoam. The final product is then obtained.

[0089] The above are the only differences between this comparative example and Example 1; all other aspects are the same.

[0090] Performance testing

[0091] 1. Fire resistance test: The test references ISO 834-1:2025. The fire retardant liquid is applied to a 75mm thick structure of 8 layers of tempered glass + 7 layers of fire retardant adhesive. The structure is heated according to the standard time-temperature curve, T=345log10(8t+1)+20. The temperature of the unexposed side is monitored and the failure is observed. The results are recorded until failure and the failure time is recorded. The failure time results are recorded in Table 1.

[0092] 2. Heat insulation test: Similar to the fire resistance test, fire retardant liquid was applied to a 75mm thick 8-layer tempered glass + 7-layer fire retardant structure. A high temperature of 950℃ was applied to the fire-facing side. Thermocouples were used to monitor the temperature change of the un-fired side, and the highest temperature rise of the un-fired side was recorded. The results are recorded in Table 1.

[0093] 3. Water resistance test: Apply fire retardant liquid to the surface of the substrate, dry it, immerse it in water, soak it completely for 24 hours, take it out, absorb the surface moisture with paper towels, let it stand for 4 hours, and then observe the blistering and peeling phenomena on the surface. If any phenomenon occurs, it is recorded as unqualified, otherwise it is qualified. The results of 50 sets of tests are recorded in Table 1.

[0094] 4. Moisture absorption rate: The fire retardant liquid was coated on a 100mm×100mm glass plate, dried to form a film, and weighed. Then it was placed in a constant temperature and humidity chamber at 25±1℃ and 85±2% relative humidity for 48h. After taking it out, it was weighed again and the moisture absorption rate was calculated. Moisture absorption rate = (mass after moisture absorption - mass before moisture absorption) / mass before moisture absorption × 100%. The result was the average of 10 tests and recorded in Table 1.

[0095] 5. Storage stability: Place 300 mL of sample into a sealed container, put it in a constant temperature oven at 60±2℃, let it stand for 168 h, take it out and let it return to room temperature, and then perform a viscosity test with the original sample that has not been heated and stored. Record the viscosity change rate in Table 1.

[0096] Table 1 Performance Test Results

[0097] Example 1 183 87.6 100 0.67 4.27 Example 2 177 90.1 100 0.75 4.14 Example 3 179 89.4 100 0.74 4.92 Comparative Example 1 155 110.3 90 3.24 9.31 Comparative Example 2 161 107.4 88 3.55 10.21 Comparative Example 3 170 97.6 92 2.07 7.65 Comparative Example 4 163 98.2 96 1.92 6.24 Comparative Example 5 166 99.1 94 2.22 6.83

[0098] Analysis of test results: Examples 1-3 achieved superior performance test results compared to Comparative Examples 1-5. Examples 1-3, by employing the functional composition scheme and preparation method specified in this application, formed a boron-phosphorus-silicon hybrid structure, significantly reducing the coating's moisture absorption, filling micropores, and improving adhesion strength. Furthermore, they greatly improved the batch stability of the final potassium silicate solution modulus, solving the technical problems of easy gelation due to excessively high modulus and poor performance due to excessively low modulus, thus providing a foundation for improving the overall performance of the fire retardant. In contrast, Comparative Examples 1-5, due to employing different technical solutions than those in this application, significantly reduced the effectiveness of their respective raw materials and preparation steps, ultimately resulting in a marked decline in the overall performance of the prepared fire retardant.

[0099] The above description is the preferred embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principles described in this application, and these improvements and modifications should also be considered within the scope of protection of this application.

Claims

1. A nanosilica glass inorganic fireproofing fluid, characterized in that: The raw material formula, by weight, includes: 100-130 parts deionized water, 45-60 parts potassium hydroxide, 60-75 parts quartz sand, 130-170 parts silica sol, 0.6-1.2 parts defoamer, 6-10 parts glycerol, 1-2 parts wetting and dispersing agent, 0.1-0.3 parts preservative, 3-5 parts antifreeze, and 9-15 parts combined functional agent; The silica sol is a combination of large-particle-size silica sol and small-particle-size silica sol, with a mass ratio of (8.5~10.5):(4.5~6). The average particle size of the large-particle-size silica sol is 50~100nm; the average particle size of the small-particle-size silica sol is 10~30nm. The defoamer is at least one of the modified organosilicon defoamers; The combined functional agent is a combination of boric acid, aluminum dihydrogen phosphate and calcium formate, in a mass ratio of (3~5):(4~6):(2~3).

2. The nanosilica glass inorganic fireproofing fluid of claim 1, characterized in that: The mass ratio of potassium hydroxide, quartz sand and silica sol is (48~55):(62~70):(135~160).

3. The nanosilica glass inorganic fireproofing fluid of claim 2, characterized in that: The quartz sand is high-purity quartz sand; the SiO2 content of the high-purity quartz sand is ≥99.5%.

4. The nanosilica glass inorganic fireproofing fluid of claim 3, characterized in that: The average mesh size of the high-purity quartz sand is 300~600 mesh.

5. The nanosilica glass inorganic fireproofing fluid of claim 4, characterized in that: The mass ratio of potassium hydroxide, glycerol and the combined functional agent is (48~55):(8~10):(11~14).

6. The nano-silicon glass inorganic fire retardant liquid according to claim 5, characterized in that: The wetting and dispersing agent is sodium polyacrylate or ammonium polyacrylate.

7. The nano-silicon glass inorganic fire retardant liquid according to claim 6, characterized in that: The antifreeze is a combination of ethylene glycol and propylene glycol in a mass ratio of (1~2):(1~2).

8. The nano-silicon glass inorganic fire retardant liquid according to claim 7, characterized in that: The preservative is isothiazolinone or benzoisothiazolinone.

9. The nano-silicon glass inorganic fire retardant liquid according to claim 8, characterized in that: The defoamer is FoamStar SI2210 or FoamStar ED 2528.

10. A method for preparing the nano-silicon glass inorganic fire retardant liquid according to any one of claims 1 to 9, characterized in that: Specifically, the following steps are included: S1: Add deionized water, potassium hydroxide and quartz sand to the reactor according to the ratio, start stirring to gradually raise the temperature to 80°C, keep it at the temperature and continue to raise the temperature to 170~175°C while introducing nitrogen into the reactor to stabilize the pressure, and filter the reaction liquid to obtain potassium silicate solution. S2: Transfer the potassium silicate solution to a mixing vessel equipped with heating and stirring. Heat and maintain the temperature of the solution in the vessel at 78~82℃. Add large-particle silica sol at a rate of 8~10 parts / min while stirring, and add some defoamer at the same time. After the addition is complete, continue stirring. Then add small-particle silica sol and the remaining defoamer at the same rate. After that, add glycerol and wetting and dispersing agent and stir evenly. S3: Add the combined functional agent, preservative and antifreeze in sequence, stirring until completely mixed after each addition. Then let it cool naturally and stand to defoam. The finished product is ready.