Aerogel-modified solvent-free epoxy fire retardant coating and preparation method thereof

Abstract

The invention discloses a solvent-free epoxy fireproof coating based on aerogel modification and a preparation method thereof. The coating is prepared from the following raw materials in parts by weight: 40% to 60% of E51 epoxy resin, 10% to 20% of phenolic modified epoxy resin, 5% to 10% of aerogel modified material, 10% to 15% of aluminum hydroxide, 8% to 12% of ammonium polyphosphate, 15% to 20% of polyamide curing agent, 0.5% to 1% of coupling agent, 0.2% to 0.5% of leveling agent, and 0.2% to 0.5% of defoaming agent. The coating adopts a solvent-free formula, has low VOC emission, and meets environmental protection requirements. The introduction of aerogel material effectively reduces the thermal conductivity of the coating, improves the thermal insulation performance, and enables efficient fire protection to be achieved at a thinner coating thickness. The addition of phenolic modified epoxy resin improves the mechanical strength and heat resistance of the coating. The synergistic effect of phenolic modified epoxy resin and aerogel significantly improves the upper temperature resistance limit of the coating, and the coating can maintain stability for a longer time in a high temperature environment of hydrocarbon fire.

Description

Technical Field

[0001] The present invention belongs to the technical field of fire retardant coatings, and more specifically, relates to an aerogel-modified solvent-free epoxy fire retardant coating and a preparation method thereof. Background Art

[0002] In modern industrial scenarios, hydrocarbon fires (HC fires) place extremely high demands on the performance of fire retardant coatings due to the high calorific value of the fuel and rapid temperature rise (refer to ISO 22899 standard). Although traditional solvent-free epoxy fire retardant coatings are environmentally friendly (low VOC emissions), their thermal conductivity is relatively high (about 0.2 W / m·K). In order to achieve the protection target (steel plate temperature does not exceed 300°C), the coating thickness needs to be designed to be 15 to 20 mm. This not only increases the amount of materials and construction costs, but also leads to increased structural loads (about 15% to 20%), which is greatly limited in terms of economy and practicality. Traditional coatings have high thermal conductivity (0.2 W / m·K), insufficient thermal insulation performance, and heat can be quickly transferred to the substrate, which cannot meet the needs of thin layer efficient protection. Traditional aerogel powders (such as SiO 2 Aerogel) is easy to agglomerate when directly added to the epoxy system, resulting in uneven porosity inside the coating and a 30% to 50% decrease in tensile strength. Traditional aerogel powder uses pure silica aerogel, which has insufficient overall heat resistance and cannot meet the extreme working conditions of 1100°C fire protection. The upper limit of pure E51 epoxy resin is about 200°C, and its long-term stability in hydrocarbon fires is insufficient.

[0003] Therefore, there is an urgent need for a new type of fire retardant coating that can significantly reduce thermal conductivity, improve thermal insulation performance, and enhance high temperature resistance while maintaining environmental protection to meet the high performance requirements of modern industry for fire retardant coatings. Summary of the invention

[0004] In view of the above defects or improvement needs of the prior art, the present invention provides a method for preparing a solvent-free epoxy fire-retardant coating based on aerogel modification, which effectively reduces the thermal conductivity of the coating and improves the thermal insulation performance by introducing aerogel materials. The modified aerogel can improve the foaming and expansion state of the fire-retardant coating, forming a more uniform pore structure, thereby increasing the foaming ratio and enhancing the thermal insulation effect; the addition of phenolic modified epoxy resin improves the mechanical strength and heat resistance of the coating, while the uniform dispersion of aerogel avoids the problem of uneven porosity inside the coating, significantly improving the tensile strength and adhesion; the synergistic effect of phenolic modified epoxy resin and aerogel significantly improves the upper temperature resistance of the coating, and can maintain stability for a longer time in the high temperature environment of hydrocarbon fires; the coating adopts a solvent-free formula, has low VOC emissions, and meets environmental protection requirements; the coating of the present invention can achieve efficient fire protection at a thinner coating thickness, reduce material consumption and structural load, and improve economy and practicality.

[0005] In order to achieve the above object, one aspect of the present invention provides a solvent-free epoxy fire retardant coating based on aerogel modification, which is prepared from the following raw materials in parts by weight: 40% to 60% of E51 epoxy resin, 10% to 20% of phenolic modified epoxy resin, 5% to 10% of aerogel modified material, 10% to 15% of aluminum hydroxide, 8% to 12% of ammonium polyphosphate, 15% to 20% of polyamide curing agent, 0.5% to 1% of coupling agent, 0.2% to 0.5% of leveling agent, and 0.2% to 0.5% of defoaming agent;

[0006] The preparation of the aerogel modified material comprises the following steps:

[0007] S1: Immersing high-silica chopped fibers in an aerogel suspension, and using ultrasonic treatment to uniformly adsorb the aerogel on the surface of the high-silica chopped fibers to form an aerogel + high-silica fiber composite;

[0008] S2: subjecting the aerogel+high-silica fiber composite to surface treatment with a silane coupling agent and hydrophobization treatment to obtain a modified fiber material with aerogel coated on the surface, and storing the modified fiber material for later use.

[0009] As a further improvement of the present invention, the high-silica chopped fibers in step S1 have a diameter of 6 to 10 μm and a length of 3 to 5 mm.

[0010] As a further improvement of the present invention, the aerogel powder accounts for 20% to 30% of the aerogel suspension in step S1; and the ultrasonic treatment time is 10 to 20 min.

[0011] As a further improvement of the present invention, the aerogel powder is a composite aerogel mixed with silicon dioxide and aluminum oxide; the proportion of aluminum oxide is 10%-30%; and the specific surface area is ≥600 m² / g.

[0012] As a further improvement of the present invention, the aerogel+high-silica fiber composite is subjected to silane coupling agent surface treatment and hydrophobic treatment in step S2, comprising:

[0013] S21: spraying the silane coupling agent solution on the surface of the aerogel + high-silica fiber composite after the treatment in step S1 to ensure that the fiber surface is evenly covered, and drying at 60° C. to allow the coupling agent to chemically bond with the fiber surface and enhance the interface bonding force between the fiber and the aerogel;

[0014] S22: immersing the fiber composite after the coupling treatment in a hydrophobic agent solution to ensure that the fiber surface is fully wetted;

[0015] S23: placing the fiber impregnated with the hydrophobic agent in an oven at 120° C. for curing for 30 minutes;

[0016] S24: After cooling the aerogel-modified fiber material treated as above to room temperature, the aerogel-modified fiber material is sealed and packaged, and stored in a dry and ventilated environment.

[0017] As a further improvement of the present invention, the concentration of the silane coupling agent solution in step S21 is 1% to 3%.

[0018] As a further improvement of the present invention, the hydrophobic agent solution in step S23 is a methyltrimethoxysilane (MTMS) solution.

[0019] The second aspect of the present invention provides a method for preparing an aerogel-modified solvent-free epoxy fire retardant coating, which is prepared by applying the aerogel-modified solvent-free epoxy fire retardant coating, comprising the following steps:

[0020] S100: Resin mixing: 40%-60% by mass of E51 epoxy resin and 10%-20% by mass of phenolic modified epoxy resin are mixed, preheated to 60°C and stirred for 20 min to form a uniform resin matrix;

[0021] S200: Dispersing the filler, adding 10%-15% by mass of aluminum hydroxide (ATH), 8%-12% by mass of ammonium polyphosphate (APP) and 0.5%-1% by mass of a coupling agent to the resin matrix, and performing a dispersion treatment at a speed of 2000 rpm using a high-speed disperser for 30 minutes;

[0022] S300: adding the modified material, slowly adding the pre-prepared aerogel modified material with a mass percentage of 5%-10% under low-speed stirring;

[0023] S400: Curing and mixing, add 15%-20% by weight of polyamide curing agent, 0.2%-0.5% by weight of leveling agent and 0.2%-0.5% by weight of defoaming agent, and stir thoroughly to ensure that all components are mixed evenly to form a stable coating system; after stirring, discharge the coating and prepare for subsequent construction applications.

[0024] As a further improvement of the present invention, the phenolic hydroxyl content of the phenolic modified epoxy resin in step S100 is 5% to 8%.

[0025] The third aspect of the present invention provides an application of the aerogel-modified solvent-free epoxy fire retardant coating in hydrocarbon fire protection materials.

[0026] In general, the above technical solutions conceived by the present invention can achieve the following beneficial effects compared with the prior art:

[0027] (1) The present invention provides a solvent-free epoxy fire retardant coating based on aerogel modification and a preparation method thereof. By introducing aerogel modified materials, the thermal conductivity of the coating is effectively reduced, thereby greatly improving the thermal insulation performance. The thermal conductivity of Example 4 and Example 5 is reduced to 0.12 W / m·K and 0.10 W / m·K, respectively, which is significantly lower than 0.21 W / m·K of the traditional coating. In addition, the fire retardant performance test shows that the fire protection time of the coating of the present invention at a thickness of 8 mm is 1.67 times that of the traditional coating, so that the coating can achieve efficient fire protection at a thinner coating thickness, reduce the material consumption and construction cost, and reduce the structural load at the same time, significantly improving the economy and practicality of the fire retardant coating.

[0028] (2) The present invention discloses a solvent-free epoxy fire retardant coating based on aerogel modification and a preparation method thereof. The aerogel used is a composite system of aluminum oxide and silicon dioxide, with an aluminum oxide ratio of 10%-30%. By compounding an alumina-type aerogel with a better temperature resistance grade, the coating can meet the fire protection limit condition of 1100°C.

[0029] (3) The present invention discloses a solvent-free epoxy fire retardant coating based on aerogel modification and a preparation method thereof. The addition of phenolic modified epoxy resin significantly improves the upper temperature resistance limit of the coating, and can maintain stability for a longer period of time in the high temperature environment of hydrocarbon fires. The high temperature cycle test shows that after 100 hours of cyclic heating at 300°C, the mass loss rate of the coating of the present invention is only 5.8%, and the surface has only slight discoloration and no cracking, while the mass loss rate of the traditional coating reaches 12.5%, and the surface is severely cracked and powdered. This shows that the coating of the present invention has excellent stability and durability in high temperature environments.

[0030] (4) The present invention provides a solvent-free epoxy fire retardant coating based on aerogel modification and a preparation method thereof. The tensile strength and adhesion of the coating are significantly improved through the synergistic effect of phenolic modified epoxy resin and aerogel modified material. The tensile strengths of Example 4 and Example 5 are 7.8 MPa and 8.5 MPa, respectively, which are much higher than the 5.2 MPa of the traditional coating. At the same time, the uniform dispersion of the aerogel modified material avoids the problem of uneven porosity inside the coating, further enhancing the mechanical properties and durability of the coating.

[0031] (5) The present invention provides an aerogel-modified solvent-free epoxy fire retardant coating and a preparation method thereof. The three-dimensional network structure of the aerogel used can effectively block the penetration of corrosive ions. At the same time, the addition of aluminum hydroxide and ammonium polyphosphate further enhances the corrosion resistance of the coating, making it suitable for outdoor and complex environments.

[0032] (6) The aerogel-modified solvent-free epoxy fire retardant coating and its preparation method of the present invention adopt a solvent-free formula, have low VOC emissions, and meet environmental protection requirements. At the same time, the addition of leveling agent and defoaming agent improves the construction performance of the coating, ensures that the coating is uniform and smooth, reduces the generation of bubbles during the construction process, and improves the coating quality.

[0033] (7) The solvent-free epoxy fire retardant coating based on aerogel modification and the preparation method thereof of the present invention can flexibly optimize the performance of the coating by adjusting the proportion of each component. Example 4 and Example 5 achieve different thermal conductivity and tensile strength by adjusting the proportion of E51 epoxy resin, phenolic modified epoxy resin and aerogel modified material, which can meet the needs of different application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a schematic diagram of the morphology of an aerogel-modified solvent-free epoxy fire retardant coating under an electron microscope according to an embodiment of the present invention;

[0035] Figure 2 This is a schematic flow chart of a method for preparing a solvent-free epoxy fire retardant coating based on aerogel modification according to an embodiment of the present invention;

[0036] Figure 3 This is a schematic flow chart of a method for preparing an aerogel-modified material of an aerogel-modified solvent-free epoxy fire retardant coating according to an embodiment of the present invention;

[0037] Figure 4 This is a schematic diagram of formula optimization performance comparison of a solvent-free epoxy fire retardant coating based on aerogel modification according to an embodiment of the present invention;

[0038] Figure 5 This is a schematic diagram of a fire retardant performance test comparison of an aerogel-modified solvent-free epoxy fire retardant coating according to an embodiment of the present invention. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0040] Traditional fire retardant coatings have insufficient thermal insulation properties, causing the substrate to heat up too quickly, accelerating coating aging and failure, and failing to meet the needs of thin layer high-efficiency protection. Aerogel powder is easily agglomerated when added directly to the epoxy system, resulting in uneven porosity inside the coating, decreased tensile strength, reduced adhesion and durability of the coating, and increased the risk of coating shedding. Insufficient high temperature resistance and insufficient long-term stability in hydrocarbon fires cause fire retardant coatings to degrade rapidly in high temperature environments. In high temperature environments, traditional epoxy resins have poor aging resistance and significantly shortened service life.

[0041] Example 1

[0042] like Figure 1 As shown, one aspect of the present invention provides a solvent-free epoxy fire retardant coating based on aerogel modification, which is prepared from the following raw materials in mass percentage: 40% to 60% E51 epoxy resin, 10% to 20% phenolic modified epoxy resin, 5% to 10% aerogel modified material, 10% to 15% aluminum hydroxide, 8% to 12% ammonium polyphosphate, 15% to 20% polyamide curing agent, 0.5% to 1% coupling agent, 0.2% to 0.5% leveling agent, and 0.2% to 0.5% defoaming agent. The E51 epoxy resin is a base resin for providing adhesion and curing performance; the phenolic modified epoxy resin is used to enhance high temperature resistance (temperature resistance above 300°C); the aerogel modified material is an aerogel + high silica fiber composite for reducing thermal conductivity; the aluminum hydroxide (ATH) is a flame retardant filler for decomposition and heat absorption; the ammonium polyphosphate (APP) is an intumescent flame retardant for forming a carbon layer; the polyamide curing agent is cured at room temperature to improve the hardness of the coating; the coupling agent (KH550) is used to enhance the interface bonding between the filler and the resin; the leveling agent is used to improve the surface flatness of the coating; the defoaming agent is used to prevent the generation of bubbles during construction.

[0043] The aerogel-modified solvent-free epoxy fire-retardant coating of the present invention effectively reduces the thermal conductivity of the coating and improves the thermal insulation performance by introducing the aerogel material. The modified aerogel can improve the foaming and expansion state of the fire-retardant coating, form a more uniform pore structure, thereby improving the foaming ratio and enhancing the thermal insulation effect. The addition of phenolic modified epoxy resin improves the mechanical strength and heat resistance of the coating, while the uniform dispersion of aerogel avoids the problem of uneven porosity inside the coating, and significantly improves the tensile strength and adhesion. Through the synergistic effect of phenolic modified epoxy resin and aerogel, the upper temperature resistance limit of the coating is significantly improved, and it can maintain stability for a longer time under the high temperature environment of hydrocarbon fire. The three-dimensional network structure of the aerogel can block the penetration of corrosive ions, while the addition of aluminum hydroxide and ammonium polyphosphate further improves the corrosion resistance of the coating, and is suitable for outdoor and complex environments. The coating of the present invention adopts a solvent-free formula, has low VOC emissions, and meets environmental protection requirements. At the same time, the addition of leveling agent and defoamer improves the construction performance of the coating and ensures that the coating is uniform and smooth. Due to the improvement of thermal insulation performance, the coating of the present invention can achieve efficient fire protection at a thin coating thickness, reduce the amount of materials and structural load, and improve economy and practicality. The aerogel-modified solvent-free epoxy fire retardant coating of the present invention shows significant advantages in terms of thermal insulation, mechanical properties, high temperature resistance, corrosion resistance and environmental protection, and is suitable for the high performance requirements of fire retardant coatings in modern industry.

[0044] Example 2

[0045] like Figure 2 As shown, the second aspect of the present invention provides a method for preparing an aerogel-modified material based on an aerogel-modified solvent-free epoxy fire retardant coating, comprising the following steps:

[0046] S1: Immerse high-silica chopped fibers with a diameter of 6 to 10 μm and a length of 3 to 5 mm in an aerogel suspension containing 20% ​​to 30% aerogel powder, and perform ultrasonic treatment for 10 to 20 min to uniformly adsorb the aerogel on the surface of the high-silica chopped fibers to form an aerogel + high-silica fiber composite;

[0047] S2: performing a silane coupling agent surface treatment and a hydrophobic treatment on the aerogel+high-silica fiber composite to obtain a modified fiber material with aerogel coated on the surface, and storing the modified fiber material for later use;

[0048] Furthermore, step S1 includes

[0049] S11: Preparation of aerogel suspension

[0050] Mix high-purity aerogel powder and deionized water in proportion so that the proportion of aerogel powder reaches 20% to 30%; ensure that the aerogel powder is evenly dispersed in the water through high-speed stirring or mechanical dispersion to form a stable aerogel suspension;

[0051] S12: Pretreatment of high silica chopped fibers

[0052] Select high-silica short-cut fibers with a diameter of 6 to 10 μm and a length of 3 to 5 mm, and completely immerse them in the aerogel suspension to ensure that the fiber surface is fully infiltrated by the suspension; perform ultrasonic treatment for 10 to 20 minutes, and use the cavitation effect of ultrasonic waves to uniformly adsorb the aerogel on the fiber surface to form a uniform aerogel coating;

[0053] The high-purity aerogel powder described in step S11 is a composite aerogel mixed with silicon dioxide and aluminum oxide; the proportion of aluminum oxide is 10%-30%; the specific surface area is ≥600 m² / g, and it has low density, high porosity and excellent thermal insulation performance; by compounding alumina aerogel with better temperature resistance grade, it can meet the extreme working condition of 1100°C fire protection.

[0054] The high-silica chopped fibers described in step S12 have good high temperature resistance and mechanical strength, and can effectively enhance the mechanical properties of the aerogel modified material.

[0055] Furthermore, in step S2, the aerogel+high-silica fiber composite is subjected to a silane coupling agent surface treatment and a hydrophobic treatment, including:

[0056] S21: spraying the silane coupling agent solution on the surface of the aerogel + high-silica fiber composite after the treatment in step S1 to ensure that the fiber surface is evenly covered, and drying at 60° C. to allow the coupling agent to chemically bond with the fiber surface and enhance the interface bonding force between the fiber and the aerogel;

[0057] S22: immersing the fiber composite after the coupling treatment in a hydrophobic agent solution to ensure that the fiber surface is fully wetted;

[0058] S23: The fiber impregnated with the hydrophobic agent is placed in an oven at 120° C. for curing for 30 minutes. During the curing process, MTMS forms a hydrophobic film on the fiber surface, further improving the water resistance and stability of the material.

[0059] S24: After cooling the aerogel modified fiber material treated as above to room temperature, the material is sealed and packaged, and stored in a dry and ventilated environment to avoid moisture and contamination;

[0060] The modified fiber material can be used in the subsequent preparation of fire-retardant coatings, significantly improving the thermal insulation and mechanical properties of the coatings.

[0061] Furthermore, the concentration of the silane coupling agent solution in step S21 is 1% to 3%, and is prepared by dissolving the silane coupling agent (KH560) in an appropriate amount of ethanol or water; the hydrophobic agent solution in step S23 is a methyltrimethoxysilane (MTMS) solution.

[0062] Furthermore, in step S11, adding an appropriate amount of dispersant (such as polyethylene glycol) to the aerogel suspension can further improve the stability of the suspension and prevent the aerogel powder from agglomerating during the impregnation process. Before the coupling treatment in step S21, the fiber can be subjected to surface activation treatment (such as plasma treatment) to further improve the activity of the fiber surface and enhance the adhesion of the coupling agent.

[0063] Example 3

[0064] like Figure 3 As shown, the third aspect of the present invention provides a method for preparing a solvent-free epoxy fire retardant coating based on aerogel modification, which is implemented by applying the aforementioned aerogel modified material, and comprises the following steps:

[0065] S100: Resin mixing: E51 epoxy resin and phenolic modified epoxy resin are mixed in proportion (E51 epoxy resin mass percentage is 40%-60%, phenolic modified epoxy resin mass percentage is 10%-20%), preheated to 60°C and stirred for 20 minutes;

[0066] Specifically, the E51 epoxy resin and the phenolic modified epoxy resin were accurately weighed in a predetermined ratio, added to the reactor, and preheated to 60°C. Stirring was continued at this temperature for 20 minutes to ensure that the two resins were fully mixed to form a uniform resin matrix. This step is the basic guarantee for the performance of the coating. Preheating and stirring can effectively improve the compatibility and reactivity of the resin.

[0067] S200: Dispersing the filler, adding 10%-15% by mass of aluminum hydroxide (ATH), 8%-12% of ammonium polyphosphate (APP) and 0.5%-1% of a coupling agent to the resin matrix in sequence, and performing a dispersion treatment at a speed of 2000 rpm using a high-speed disperser for 30 minutes; this process is intended to ensure that the filler is evenly distributed in the resin system, and at the same time, through the action of the coupling agent, the interface bonding force between the filler and the resin is enhanced, thereby improving the overall performance of the coating;

[0068] S300: adding the modified material, slowly adding the pre-prepared aerogel modified material with a mass percentage of 5%-10% under low-speed stirring (500 rpm); in this step, special attention should be paid to the control of the stirring speed to avoid damaging the fiber structure in the aerogel modified material, thereby ensuring that the integrity and functionality of the material are retained;

[0069] S400: Curing and mixing, add 15%-20% by weight of polyamide curing agent, 0.2%-0.5% by weight of leveling agent and 0.2%-0.5% by weight of defoaming agent, and stir thoroughly to ensure that all components are mixed evenly to form a stable coating system; after stirring, discharge the coating and prepare for subsequent construction applications.

[0070] Furthermore, the phenolic hydroxyl content of the phenolic modified epoxy resin in step S100 is 5% to 8%.

[0071] It should be noted that during the resin mixing and filler dispersion process, the temperature and stirring time must be strictly controlled to ensure uniform mixing and avoid overreaction; when adding aerogel modified materials, the stirring speed can be appropriately adjusted to ensure uniform dispersion of the materials while minimizing the risk of fiber breakage; according to the specific performance requirements of the coating, the addition order and amount of additives (such as leveling agents, defoaming agents) should be optimized to further improve the construction performance and final performance of the coating.

[0072] Example 4

[0073] The only difference from Example 3 is:

[0074] The mass percentage of the E51 epoxy resin used in step S100 is 45%, and the mass percentage of the phenolic modified epoxy resin is 15%;

[0075] The mass percentage of aluminum hydroxide (ATH) used in step S200 is 10%, and the mass percentage of ammonium polyphosphate (APP) is 12%;

[0076] The mass percentage of the aerogel modified material in step S300 is 10%.

[0077] The thermal conductivity of the aerogel-modified solvent-free epoxy fire retardant coating prepared in Example 4 is 0.12 W / m·K, and the tensile strength is 7.8 MPa.

[0078] Example 5

[0079] The only difference from Example 3 is:

[0080] The mass percentage of the E51 epoxy resin used in step S100 is 50%, and the mass percentage of the phenolic modified epoxy resin is 10%;

[0081] The mass percentage of aluminum hydroxide (ATH) used in step S200 is 12%, and the mass percentage of ammonium polyphosphate (APP) is 10%;

[0082] The mass percentage of the aerogel modified material in step S300 is 8%.

[0083] The thermal conductivity of the aerogel-modified solvent-free epoxy fire retardant coating prepared in Example 5 is 0.10 W / m·K, and the tensile strength is 8.5 MPa.

[0084] Comparative Example 1

[0085] The only difference from Example 3 is:

[0086] The mass percentage of the E51 epoxy resin used in step S100 is 60%, and the mass percentage of the phenolic modified epoxy resin is 0%;

[0087] The mass percentage of aluminum hydroxide (ATH) used in step S200 is 15%, and the mass percentage of ammonium polyphosphate (APP) is 10%;

[0088] The mass percentage of the aerogel modified material in step S300 is 0%.

[0089] The thermal conductivity of the aerogel-modified solvent-free epoxy fire retardant coating prepared in Comparative Example 1 is 0.21 W / m·K, and the tensile strength is 5.2 MPa.

[0090] As shown in Table 1 and Figure 4 As shown, by comparing Example 4, Example 5 and Comparative Example 1, it can be seen that with the increase in the proportion of aerogel modified material and phenolic modified epoxy resin, the thermal conductivity of the prepared fire retardant coating is significantly reduced, and the tensile strength is maintained at a high level.

[0091] Table 1 Comparison of formulation optimization

[0092]

[0093] Furthermore, by testing the fire retardant performance of the aerogel-modified solvent-free epoxy fire retardant coating of the present invention, it can be seen that the aerogel-modified solvent-free epoxy fire retardant coating of the present invention shows a significant performance improvement. Specifically, the traditional solvent-free epoxy coating can control the temperature of the steel plate below 300°C for 36 minutes at a thickness of 8 mm; while the coating of the present invention (Example 1) has a defense time of 60 minutes at the same thickness, and the performance is improved by 66.7%. In addition, the coating of the present invention (Example 2) can achieve a defense time of 45 minutes at a thickness of 6 mm, while the traditional coating requires a thickness of 12 mm to achieve the same performance. This shows that the defense time of the coating of the present invention at a thickness of 8 mm is 1.67 times that of the traditional coating, achieving thin layer efficient protection and significantly improving the economy and practicality of the fire retardant coating; please see Table 2 and for details. Figure 5 .

[0094] Table 2 Fire performance test table

[0095]

[0096] Furthermore, in the high temperature cycle test, the aerogel-modified solvent-free epoxy fire retardant coating of the present invention exhibited excellent high temperature resistance. In the test, the coating sample was placed in an oven at 300°C for cyclic heating, and each cycle lasted for 2 hours. After 100 hours of continuous testing, the mass loss rate and surface state of the coating were evaluated. The results showed that the mass loss rate of the traditional coating reached 12.5% ​​after 100 hours, and severe cracking and powdering occurred on the surface; while the mass loss rate of the coating of the present invention was only 5.8%, and the surface had only slight discoloration and no cracking. This shows that the stability of the coating of the present invention in a high temperature environment is significantly better than that of the traditional coating, and can effectively resist the performance degradation and structural damage caused by high temperature, thereby extending the service life of the coating and improving its reliability under extreme conditions. Please see Table 3 for details.

[0097] Table 3 High temperature resistance performance test table

[0098]

[0099] In the prior art, there are some challenges and defects in the process of compounding aerogel with high-silica chopped fibers and then adding epoxy resin. First, the ultra-low density and hydrophobicity of aerogel make it difficult to disperse evenly in epoxy resin. This uneven dispersion may cause voids or air pockets to appear inside the composite material, which in turn affects the overall performance of the material. In addition, when high-silica chopped fibers are directly mixed with epoxy resin, problems such as poor adhesion and weak structural integrity may occur. These problems not only weaken the strength and durability of the composite material, but also reduce its performance in applications such as fire protection and thermal insulation.

[0100] In order to solve these problems, the present invention proposes an improved method; by adding fibers (such as high-silica chopped fibers) during the preparation of aerogels, or adding aerogel particles to the spinning solution, the uniformity and performance of the composite material can be improved. In addition, a specific surface treatment (such as coupling agent modification) is used to enhance the interfacial bonding between aerogels and epoxy resins, thereby improving the mechanical properties and durability of the composite material. These improvement measures provide new ideas and methods for the development of high-performance aerogel / high-silica chopped fibers / epoxy resin composite materials.

[0101] Compounding aerogel with high-silica chopped fibers and adding them to epoxy resin has many significant advantages:

[0102] Significantly improved thermal insulation performance: Aerogel itself has an extremely low thermal conductivity. When it is combined with high-silicon short-cut fibers and added to epoxy resin, the thermal conductivity of the composite material can be significantly reduced. For example, the room temperature thermal conductivity of SiOC aerogel / flexible ceramic fiber composites can be as low as 0.026 W / m·K, and the thermal conductivity is reduced by 47% at high temperatures, showing excellent thermal insulation performance.

[0103] Enhanced mechanical properties: The composite structure of high-silica chopped fibers and aerogel can effectively enhance the mechanical properties of epoxy resin. High-silica chopped fibers provide good mechanical support, while aerogel fills the pores between fibers, making the composite material significantly improved in strength and toughness while maintaining a low density.

[0104] Improved flexibility and durability: The composite material not only maintains the flexibility of high-silica chopped fibers, but also enhances the resilience and durability of the material through the porous structure of the aerogel. This composite structure protects the fibers under high temperature or mechanical load, further extending the service life of the material.

[0105] High temperature resistance and oxidation resistance: Aerogel / high silica chopped fiber composites show excellent stability in high temperature environments. For example, after calcining SiOC aerogel composites in air at 1200°C for 1 hour, the mass loss is only 1%, showing excellent high temperature resistance and oxidation resistance.

[0106] Enhanced hydrophobicity: The hydrophobicity of aerogel can effectively improve the waterproof performance of the composite material, enabling it to maintain good thermal insulation and mechanical properties in a humid environment.

[0107] Reduce material density: The low density of aerogel allows the composite material to have a lower overall density while maintaining excellent performance, making it suitable for application scenarios with strict requirements on weight.

[0108] Multifunctional integration: Aerogel / high-silica chopped fiber / epoxy resin composite material integrates multiple functions such as thermal insulation, sound insulation, hydrophobicity, and high temperature resistance. It is a high-performance multifunctional material that is widely used in aerospace, building energy conservation, high temperature protection and other fields.

[0109] The aerogel-modified solvent-free epoxy fire retardant coating of the present invention is prepared by compounding aerogel with high-silica chopped short fibers and then adding them to epoxy resin. It can significantly reduce the thermal conductivity, improve the thermal insulation performance, and enhance the high temperature resistance while maintaining environmental protection. It shows significant advantages in terms of thermal insulation, mechanical properties, high temperature resistance, corrosion resistance, and environmental protection. It can solve the problem that the traditional fire retardant coating has insufficient thermal insulation performance and high thermal conductivity, which leads to rapid heat transfer to the substrate, and cannot meet the demand for thin layer high-efficiency protection. The coating thickness needs to be increased to achieve the protection goal, resulting in increased material usage and construction costs. The problem of increased structural load, aerogel powder is easy to agglomerate when directly added to the epoxy system, resulting in uneven porosity inside the coating, a 30%-50% decrease in tensile strength, reduced adhesion and durability of the coating, and an increased risk of coating shedding. In addition, traditional epoxy resins have limited high temperature resistance, with an upper temperature resistance limit of only about 200°C, insufficient long-term stability in hydrocarbon fires, and a greatly shortened service life, making it difficult to meet the high performance requirements of modern industry for fire retardant coatings. The present invention can significantly improve the comprehensive performance of composite materials and meet the diverse needs of modern industry for high-performance materials.

[0110] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A solvent-free epoxy fire retardant coating based on aerogel modification, characterized in that: The invention is prepared from the following raw materials in percentage by weight: 40% to 60% of E51 epoxy resin, 10% to 20% of phenolic modified epoxy resin, 5% to 10% of aerogel modified material, 10% to 15% of aluminum hydroxide, 8% to 12% of ammonium polyphosphate, 15% to 20% of polyamide curing agent, 0.5% to 1% of coupling agent, 0.2% to 0.5% of leveling agent, and 0.2% to 0.5% of defoaming agent; The preparation of the aerogel modified material comprises the following steps: S1: Immersing high-silica chopped fibers in an aerogel suspension, and using ultrasonic treatment to uniformly adsorb the aerogel on the surface of the high-silica chopped fibers to form an aerogel + high-silica fiber composite; the aerogel used is a composite system of alumina and silica, with the proportion of alumina being 10%-30%; S2: performing a silane coupling agent surface treatment and a hydrophobic treatment on the aerogel+high-silica fiber composite to obtain a modified fiber material with aerogel coated on the surface, and storing the modified fiber material for later use; The preparation of the solvent-free epoxy fire retardant coating based on aerogel modification comprises the following steps: S100: Resin mixing: 40%-60% by mass of E51 epoxy resin and 10%-20% by mass of phenolic modified epoxy resin are mixed, preheated to 60°C and stirred for 20 min to form a uniform resin matrix; S200: Dispersing the filler, adding 10%-15% by mass of aluminum hydroxide, 8%-12% by mass of ammonium polyphosphate and 0.5%-1% by mass of a coupling agent to the resin matrix, and performing a dispersion treatment at a speed of 2000 rpm using a high-speed disperser for 30 minutes; S300: adding the modified material, slowly adding the pre-prepared aerogel modified material with a mass percentage of 5%-10% under low-speed stirring; S400: Curing and mixing, add 15%-20% by weight of polyamide curing agent, 0.2%-0.5% by weight of leveling agent and 0.2%-0.5% by weight of defoaming agent, stir well to form a stable coating system; discharge the coating and prepare for subsequent construction applications.

2. The solvent-free epoxy fire retardant coating based on aerogel modification according to claim 1, characterized in that: The high-silica chopped fibers in step S1 have a diameter of 6 to 10 μm and a length of 3 to 5 mm.

3. The aerogel-modified solvent-free epoxy fire retardant coating according to claim 1, characterized in that: The aerogel powder accounts for 20% to 30% of the aerogel suspension in step S1; and the ultrasonic treatment time is 10 to 20 min.

4. The aerogel-modified solvent-free epoxy fire retardant coating according to claim 3, characterized in that: The aerogel powder is a composite aerogel mixed with silicon dioxide and aluminum oxide; the proportion of aluminum oxide is 10%-30%; and the specific surface area is ≥600 m² / g.

5. The aerogel-modified solvent-free epoxy fire retardant coating according to claim 1, characterized in that: The step S2 of performing silane coupling agent surface treatment and hydrophobic treatment on the aerogel+high silica fiber composite comprises: S21: spraying a silane coupling agent solution on the surface of the aerogel + high-silica fiber composite after the treatment in step S1 to ensure that the fiber surface is evenly covered, and drying at 60° C. to allow the coupling agent to chemically bond with the fiber surface and enhance the interface bonding force between the fiber and the aerogel; S22: immersing the fiber composite after the coupling treatment in a hydrophobic agent solution to ensure that the fiber surface is fully wetted; S23: placing the fiber impregnated with the hydrophobic agent in an oven at 120° C. for curing for 30 minutes; S24: After cooling the aerogel-modified fiber material treated as above to room temperature, the aerogel-modified fiber material is sealed and packaged, and stored in a dry and ventilated environment.

6. The aerogel-modified solvent-free epoxy fire retardant coating according to claim 5, characterized in that: The concentration of the silane coupling agent solution in step S21 is 1% to 3%.

7. The aerogel-modified solvent-free epoxy fire retardant coating according to claim 5, characterized in that: In step S23, the hydrophobic agent solution is a methyltrimethoxysilane solution.

8. The aerogel-modified solvent-free epoxy fire retardant coating according to any one of claims 1 to 7, characterized in that: The phenolic hydroxyl content of the phenolic modified epoxy resin in step S100 is 5% to 8%.

9. Use of the aerogel-modified solvent-free epoxy fire retardant coating according to any one of claims 1 to 7 in hydrocarbon fire protection materials.

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