A method for preparing a fire-resistant silica-phenol-formaldehyde resin aerogel blanket for a bridge

Abstract

The application discloses a preparation method of a bridge fire-resistant silica-phenolic resin aerogel felt, and comprises the following steps: (1) mixing raw materials, i.e., sodium silicate, aluminum silicate, ethanol and water, in a container at room temperature, stirring for about 15 min, and adding acetic acid to obtain a sol; (2) placing the sol and a phenolic resin mixed solution into a reaction container to form a gel body, coating the gel body on a supporting material to form a silica-phenolic resin aerogel felt precursor; and (3) placing the gel felt in ethanol for soaking to make the gel felt absorb moisture and become soft, and finally preparing the fire-resistant flexible silica-phenolic resin aerogel felt through a vacuum freeze-drying method.

Description

Technical Field

[0001] This invention relates to the field of fire-resistant materials technology, and more specifically to a method for preparing a silica-phenolic resin aerogel felt for fire-resistant bridges. Background Technology

[0002] With the increasing global population and rapid urbanization, transportation demand is constantly growing. Long-span bridges can cross complex geographical environments such as rivers, canyons, bays, or cities, providing vital transportation connections, reducing travel time, and promoting economic and social development. The fire safety of long-span bridges is one of the key research issues. Researchers are dedicated to developing more advanced fire-resistant materials for bridges to ensure that long-span bridges maintain good fire resistance throughout their service life. With the accelerating pace of urbanization and the rapid development of transportation, the fire protection requirements for bridges are becoming increasingly prominent. Traditional fire-resistant materials such as rock wool and fiberglass have some shortcomings, such as easy moisture absorption, easy corrosion, and poor thermal conductivity. Therefore, developing a new type of fire-resistant material to improve the flame-retardant and fire-resistant properties of bridges has become an important research topic.

[0003] Phenolic resin aerogel is a porous material made from phenolic resin. Phenolic resin aerogel felts possess excellent fire resistance; their low thermal conductivity and excellent thermal insulation properties enable them to withstand high temperatures and maintain structural stability. This has made them highly sought after in fire-resistant material applications in the construction and industrial sectors.

[0004] Silica aerogel is a porous material characterized by low density, large specific surface area, and excellent thermal resistance. It is prepared from a silica mass reaction system through processes such as gelation, drying, and annealing. Silica aerogel felts possess good fire resistance, thermal insulation properties, and chemical corrosion resistance, and are therefore widely used in the field of fire protection materials.

[0005] The key to preparing silica-phenolic resin aerogel felts lies in determining the appropriate ratio of phenolic resin to silica, the gelation reaction conditions, and the drying and annealing process. By adjusting these factors, the pore structure, density, and mechanical properties of the aerogel felt can be controlled, thereby achieving better fire resistance.

[0006] In conclusion, the research on the preparation process of silica-phenolic resin aerogel felt is an important and challenging technology. By thoroughly studying factors such as the ratio of silica to phenolic resin, gelation reaction conditions, and drying processes, the preparation process of aerogel felt can be optimized, thereby improving the fire resistance of bridges. This will contribute to enhancing the fire resistance of urban bridges and protecting public safety and property.

[0007] Therefore, how to provide a method for preparing bridge fire-resistant silica-phenolic resin aerogel felt with reasonable proportions, simple operation, and simple process is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0008] To address the problems existing in the prior art, the purpose of this invention is to provide a method for preparing silica-phenolic resin aerogel felt for fire-resistant bridges, which greatly reduces costs while taking into account the weight, mechanical properties, and thermal insulation capabilities of fire-resistant fiber felt.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] This invention involves obtaining a sol by stirring a silicon source with ethanol and water, then uniformly mixing the sol with phenolic resin to form a gel. The resulting gel is then applied to a support material via coating to form a silica-phenolic resin aerogel mat precursor. After softening with ethanol, a fire-resistant flexible silica-phenolic resin aerogel mat is finally prepared.

[0011] Furthermore, the present invention provides a method for preparing a silica-phenolic resin aerogel felt for fire-resistant bridges, comprising the following steps:

[0012] (1) Mix the silicon source and solvent at room temperature, then add water and stir thoroughly. Then add an acidic catalyst to adjust the pH and continue stirring to obtain a sol.

[0013] (2) Mix the sol and phenolic resin evenly, then place them in a reaction vessel and react at a certain temperature to form a gel. Coat the obtained gel onto the support material to form a silica-phenolic resin aerogel felt precursor.

[0014] (3) At room temperature, the aerogel mat precursor is immersed in an ethanol solution to soften the aerogel mat by absorbing moisture, and then vacuum freeze-drying is performed to obtain a flexible silica-phenolic resin aerogel mat.

[0015] Preferably, the silicon source in step (1) is sodium silicate and aluminum silicate; the solvent is pure ethanol.

[0016] The beneficial effects of the above-mentioned preferred method include: the introduction of dual silicon sources can effectively improve the fire resistance of the material.

[0017] Preferably, the molar ratio of sodium silicate, aluminum silicate and pure ethanol is (1-2):1:10.

[0018] Preferably, the acidic catalyst in step (1) is acetic acid, and the concentration of the acetic acid is 0.6 to 1 mol / L; the pH adjustment is to adjust the pH to 2 to 4.

[0019] The beneficial effects of the above-mentioned preferred method include: an appropriate acetic acid concentration can control the hydrolysis rate within a suitable range, which is conducive to improving the material properties.

[0020] Preferably, the mass ratio of the sol to the phenolic resin in step (2) is (15-20):1.

[0021] The beneficial effects of the above-mentioned optimization include: effectively improving the flexibility of the material while maintaining excellent fire resistance and heat insulation performance.

[0022] Preferably, the mass ratio of the gel to the support material in step (2) is (2-4):1.

[0023] The beneficial effects of the above-mentioned optimization include: an appropriate ratio of gel to support material can maximize the performance of the material without wasting gel.

[0024] Preferably, the supporting material in step (2) is high silica fiber felt or glass fiber felt; the temperature is 50℃~60℃.

[0025] The beneficial effects of the above-mentioned optimization include: appropriate temperature helps to increase the activity of molecules in the sol, thereby improving the polycondensation rate and efficiency.

[0026] Preferably, the volume fraction of ethanol in the ethanol solution in step (3) is 60-70%, and the soaking time is 24-36 hours.

[0027] The beneficial effects of the above-mentioned preferred method include: sufficient wetting can further stabilize the gel skeleton structure and make the material properties more stable.

[0028] Preferably, the vacuum freeze drying in step (3) is performed at -55℃ to 65℃ for 48 to 72 hours.

[0029] The advantages of the above-mentioned preferred method include: vacuum freeze drying is convenient and can effectively prevent damage to the aerogel skeleton; the materials prepared by this method have good performance.

[0030] Preferably, the density of the silica-phenolic resin aerogel felt in step (3) is 0.15–0.25 g / cm³. 3 .

[0031] As can be seen from the above technical solution, compared with the prior art, the present invention has the following beneficial effects: it can improve the flexibility of the material to a certain extent while possessing excellent fire resistance, heat insulation and mechanical properties, thus expanding the application range of the material in bridges. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0033] Figure 1 The thermal conductivity of silica-phenolic resin aerogel felt.

[0034] Figure 2 Temperature rise curve for fire resistance test of the aerogel felt prepared in Example 1.

[0035] Figure 3 Temperature rise curve for fire resistance test of the aerogel felt prepared in Example 2.

[0036] Figure 4 Temperature rise curve for fire resistance test of the aerogel felt prepared in Example 3.

[0037] Figure 5 The bending stiffness of silica-phenolic resin aerogel felt. Detailed Implementation

[0038] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] Example 1

[0040] A process for preparing fire-resistant silica-phenolic resin aerogel felt for bridges includes the following steps:

[0041] (1) At room temperature, the raw materials sodium silicate, aluminum silicate and pure ethanol are thoroughly mixed in a container at a molar ratio of 1:1:10. Water is added and stirred thoroughly for about 15 minutes. Acetic acid with a concentration of 0.8 mol / L is added to make the pH of the mixed solution 3. Stirring is continued to obtain a sol.

[0042] (2) The sol and phenolic resin were mixed evenly at a mass ratio of 20:1. The mixture was placed in a reaction vessel and the temperature was controlled at 60°C until a viscous gel was formed. The resulting gel was applied to a 10 mm thick high-silica fiber felt by coating at a certain ratio, wherein the weight ratio of the gel added to the high-silica fiber felt was 2:1, to form a silica-phenolic resin aerogel felt precursor.

[0043] (3) At room temperature, the aerogel mat precursor was immersed in a 65% ethanol solution for 24 hours to soften the aerogel mat by absorbing moisture. Then, it was freeze-dried under vacuum at -60℃ for 72 hours to finally prepare a product with a density of 0.2 g / cm³. 3 Flexible silica-phenolic resin aerogel felt.

[0044] Example 2

[0045] A process for preparing fire-resistant silica-phenolic resin aerogel felt for bridges includes the following steps:

[0046] (1) At room temperature, the raw materials sodium silicate, aluminum silicate and pure ethanol are thoroughly mixed in a container at a molar ratio of 1:1:10. Water is added and stirred thoroughly for about 15 minutes. Acetic acid with a concentration of 0.8 mol / L is added to make the pH of the mixed solution 3. Stirring is continued to obtain a sol.

[0047] (2) The sol and phenolic resin were mixed evenly at a mass ratio of 20:1. The mixture was placed in a reaction vessel and the temperature was controlled at 60°C until a viscous gel was formed. The resulting gel was applied to a 10 mm thick high-silica fiber felt by coating at a certain ratio, wherein the weight ratio of the gel added to the high-silica fiber felt was 3:1, to form a silica-phenolic resin aerogel felt precursor.

[0048] (3) At room temperature, the aerogel mat precursor was immersed in a 65% ethanol solution for 24 hours to soften the aerogel mat by absorbing moisture. Then, it was freeze-dried under vacuum at -60℃ for 72 hours to finally prepare a product with a density of 0.2 g / cm³. 3 Flexible silica-phenolic resin aerogel felt.

[0049] Example 3

[0050] A process for preparing fire-resistant silica-phenolic resin aerogel felt for bridges includes the following steps:

[0051] (1) At room temperature, the raw materials sodium silicate, aluminum silicate and pure ethanol are thoroughly mixed in a container at a molar ratio of 1:1:10. Water is added and stirred thoroughly for about 15 minutes. Acetic acid with a concentration of 0.8 mol / L is added to make the pH of the mixed solution 3. Stirring is continued to obtain a sol.

[0052] (2) The sol and phenolic resin were mixed evenly at a mass ratio of 20:1. The mixture was placed in a reaction vessel and the temperature was controlled at 60°C until a viscous gel was formed. The resulting gel was applied to a 10 mm thick high-silica fiber felt by coating at a certain ratio, wherein the weight ratio of the gel added to the high-silica fiber felt was 4:1, to form a silica-phenolic resin aerogel felt precursor.

[0053] (3) At room temperature, the aerogel mat precursor was immersed in a 65% ethanol solution for 24 hours to soften the aerogel mat by absorbing moisture. Then, it was freeze-dried under vacuum at -60℃ for 72 hours to finally prepare a product with a density of 0.2 g / cm³. 3 Flexible silica-phenolic resin aerogel felt.

[0054] Example 4

[0055] A process for preparing fire-resistant silica-phenolic resin aerogel felt for bridges includes the following steps:

[0056] (1) At room temperature, the raw materials sodium silicate, aluminum silicate and pure ethanol are thoroughly mixed in a container at a molar ratio of 2:1:10. Water is added and stirred thoroughly for about 15 minutes. Acetic acid with a concentration of 1 mol / L is added to make the pH of the mixed solution 4. Stirring is continued to obtain a sol.

[0057] (2) The sol and phenolic resin were mixed evenly at a mass ratio of 15:1. The mixture was placed in a reaction vessel and the temperature was controlled at 50°C until a viscous gel was formed. The resulting gel was applied to a 10 mm thick high-silica fiber felt by coating at a certain ratio, wherein the weight ratio of the gel added to the high-silica fiber felt was 3:1, to form a silica-phenolic resin aerogel felt precursor.

[0058] (3) At room temperature, the aerogel mat precursor was immersed in a 60% ethanol solution for 36 hours to soften the aerogel mat by absorbing moisture. Then, it was freeze-dried under vacuum at -65℃ for 72 hours to finally prepare a product with a density of 0.25 g / cm³. 3 Flexible silica-phenolic resin aerogel felt.

[0059] Example 5

[0060] A process for preparing fire-resistant silica-phenolic resin aerogel felt for bridges includes the following steps:

[0061] (1) At room temperature, the raw materials sodium silicate, aluminum silicate and pure ethanol are thoroughly mixed in a container at a molar ratio of 1:1:10. Water is added and stirred thoroughly for about 15 minutes. Acetic acid with a concentration of 1 mol / L is added to make the pH of the mixed solution 2. Stirring is continued to obtain a sol.

[0062] (2) The sol and phenolic resin were mixed evenly at a mass ratio of 20:1. The mixture was placed in a reaction vessel and the temperature was controlled at 60°C until a viscous gel was formed. The resulting gel was applied to a 10 mm thick high-silica fiber felt by coating at a certain ratio, wherein the weight ratio of the gel added to the high-silica fiber felt was 3:1, to form a silica-phenolic resin aerogel felt precursor.

[0063] (3) At room temperature, the aerogel mat precursor was immersed in a 70% ethanol solution for 24 hours to soften the aerogel mat by absorbing moisture. Then, it was freeze-dried under vacuum at -55℃ for 72 hours to finally prepare a product with a density of 0.15 g / cm³. 3 Flexible silica-phenolic resin aerogel felt.

[0064] Performance Experiment

[0065] The thermal conductivity of the silica-phenolic resin aerogel felts prepared in Examples 1-3 was tested to evaluate their thermal insulation performance, such as... Figure 1 As shown, the thermal conductivity values ​​of the three types of aerogel felts prepared are all low, and the thermal conductivity decreases with the increase of gel content.

[0066] Fire resistance tests were conducted on the three products prepared in Examples 1-3. The composite material was wrapped and fixed to the surface of a 90mm diameter suspension wire model using an overlapping method. Fire-retardant sealant and fire-resistant fiber cloth were then applied and wrapped around the composite material surface using a three-adhesive, two-cloth method. After the sealant dried, the model was placed in an open-flame combustion furnace and subjected to a 90-minute fire resistance test at a simulated HC fire temperature. The surface temperature of the steel wire was as follows: Figure 2 , Figure 3 and Figure 4 As shown.

[0067] It can be seen that the composite material exhibits excellent fire resistance and heat insulation performance, which increases with the increase of gel content.

[0068] The silica-phenolic resin aerogel mats prepared in Examples 1-3 were subjected to stiffness tests to evaluate their flexibility. Six pieces of aerogel mat each, 250 mm in length and 25 mm in width, were cut. Using an LLY-01 electronic stiffness tester, the bending length of the material at a bending angle of 45° was measured. The average bending length was taken, and the bending stiffness of the material was calculated using the bending stiffness calculation formula. Figure 5 As shown.

[0069] It can be seen that the flexural stiffness of silica-phenolic resin aerogel felt is relatively low, in other words, silica-phenolic resin aerogel felt has good flexibility.

[0070] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0071] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a fire-resistant silica-phenolic resin aerogel felt for bridges, characterized in that, Includes the following steps: (1) Mix the silicon source and solvent at room temperature, then add water and stir thoroughly, then add an acidic catalyst to adjust the pH, and continue stirring to obtain a sol; (2) Mix the sol and phenolic resin evenly, then place them in a reaction vessel and react at a certain temperature to form a gel. Coat the obtained gel onto the support material to form a silica-phenolic resin aerogel felt precursor. (3) At room temperature, the aerogel mat precursor is immersed in an ethanol solution to soften the aerogel mat by absorbing moisture, and then vacuum freeze-drying is performed to obtain a flexible silica-phenolic resin aerogel mat. The silicon source mentioned in step (1) is sodium silicate and aluminum silicate; the solvent is pure ethanol; The molar ratio of sodium silicate, aluminum silicate and pure ethanol is (1~2):1:10; In step (2), the mass ratio of the sol to the phenolic resin is (15~20):1; and the mass ratio of the gel to the supporting material is (2~4):

1.

2. The method for preparing a silica-phenolic resin aerogel felt for fire-resistant bridges according to claim 1, characterized in that, The acidic catalyst mentioned in step (1) is acetic acid, and the concentration of the acetic acid is 0.6~1 mol / L; the pH adjustment is to adjust the pH to 2~4.

3. The method for preparing a fire-resistant silica-phenolic resin aerogel felt for bridges according to claim 1, characterized in that, The supporting material in step (2) is high silica fiber felt or glass fiber felt; the temperature is 50℃~60℃.

4. The method for preparing a fire-resistant silica-phenolic resin aerogel felt for bridges according to claim 1, characterized in that, The volume fraction of ethanol in the ethanol solution in step (3) is 60-70%, and the soaking time is 24-36h.

5. The method for preparing a fire-resistant silica-phenolic resin aerogel felt for bridges according to claim 1, characterized in that, The vacuum freeze drying in step (3) is drying at -55℃ to -65℃ for 48 to 72 hours.

6. The method for preparing a fire-resistant silica-phenolic resin aerogel felt for bridges according to claim 1, characterized in that, The density of the silica-phenolic resin aerogel felt in step (3) is 0.15~0.25 g / cm³. 3 .

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