Water-based low-smoke intumescent fire-retardant coating for steel structure, preparation method and application thereof

Abstract

This application provides a water-based low-smoke intumescent fire-retardant coating for steel structures, its preparation method, and its application, belonging to the field of fire-retardant coatings. The coating is composed of the following chemical raw materials: 25-40 parts water-based resin, 30-50 parts intumescent system, 10-15 parts smoke-suppressing functional slurry, 2-5 parts additives, and water. The intumescent system consists of ammonium polyphosphate, pentaerythritol, and melamine. The smoke-suppressing functional slurry is prepared by wet grinding of α-zirconium phosphate, molybdenum compounds, zinc-magnesium-aluminum ternary hydrotalcite, zinc borate, montmorillonite, high molecular weight ammonium polyacrylate dispersant, and water. This application achieves a smoke density level ≤34, an expansion ratio ≥28 times, and a fire resistance limit ≥143 min through the synergistic effect of five functional powders and in-situ adsorption and passivation by ammonium polyacrylate. It combines the advantages of low smoke, high expansion, water-based environmental friendliness, and simplified process, overcoming the technical challenge of simultaneously achieving smoke suppression and expansion.

Description

Technical Field

[0001] This application relates to the field of fire-retardant coating technology, and in particular to a water-based low-smoke intumescent fire-retardant coating for steel structures, its preparation method, and its application. Background Technology

[0002] Steel structures are widely used in modern architecture, but their mechanical properties deteriorate drastically at high temperatures (yield strength drops to less than 50% of room temperature at approximately 500℃, and they may lose their load-bearing capacity at 600℃), necessitating the protection of fire-retardant coatings. Intumescent fire-retardant coatings are currently the mainstream technology for fire protection of steel structures. They utilize an acid source (ammonium polyphosphate, APP), a carbon source (pentaerythritol, PER), and a gas source (melamine, MEL) to undergo a chemical reaction upon heating, forming a porous, heat-insulating carbon layer that slows heat transfer to the substrate. However, during the high-temperature decomposition process of traditional intumescent fire-retardant coatings, organic components (such as ammonium salts in APP and hydroxyl compounds in PER) are prone to incomplete combustion, releasing large amounts of dense smoke and toxic gases (such as CO and HCN). This can lead to asphyxiation and obstructed escape routes during a fire, a problem particularly pronounced in water-based systems. In recent years, in order to meet the requirements of green buildings for low VOCs coatings, water-based intumescent fireproof coatings have become the mainstream in the industry. However, the dispersion stability of inorganic smoke suppressants in water-based media is poor, and the introduction of smoke suppressants often disrupts the continuous reaction of the expansion system, resulting in the technical bottleneck of smoke suppression leading to char loss and char retention leading to high smoke levels, making it difficult to achieve a synergistic improvement in smoke suppression performance and expansion performance.

[0003] To overcome the aforementioned problems, researchers have attempted to introduce nanomaterials to modify the expansion system. For example, Chinese invention patent CN111363380A discloses a nano-zirconium phosphate-coated modified ammonium polyphosphate and an intumescent fire-retardant coating prepared using it. This technology uses a multi-step chemical synthesis to coat the surface of the exfoliated nano-zirconium phosphate onto the surface of the ammonium polyphosphate, improving the fire-retardant performance of the coating to some extent. However, this technology still has the following limitations: the modification process is complex, the reaction conditions are harsh, and industrial production is difficult; it only modifies a single component, failing to form a multi-component synergistic smoke suppression-enhancing system; and it does not solve the compatibility problem of layered zirconium phosphate with water-based resins and other powders in aqueous media, nor does it recognize the potential risk that the acidic sites on the surface of layered zirconium phosphate may catalyze the premature reaction of APP / PER at room temperature, thus affecting the storage stability and expansion performance of the coating. Therefore, how to synergistically improve the smoke suppression and expansion performance of fire-retardant coatings for steel structures is an urgent technical problem to be solved. Summary of the Invention

[0004] This application provides a water-based low-smoke intumescent fireproof coating for steel structures, its preparation method, and its application, in order to solve the following technical problem: how to synergistically improve the smoke suppression and intumescent properties of fireproof coatings for steel structures.

[0005] In a first aspect, embodiments of this application provide a water-based low-smoke intumescent fireproof coating for steel structures. By mass, the coating is composed of the following chemical raw materials: 25-40 parts of water-based resin, 30-50 parts of intumescent system, 10-15 parts of smoke-suppressing slurry, 2-5 parts of additives, and water. The expansion system is composed of ammonium polyphosphate, pentaerythritol and melamine; The smoke-suppressing slurry is made by wet grinding of zirconium α-phosphate, molybdenum compound, zinc magnesium aluminum ternary hydrotalcite, zinc borate, montmorillonite, high molecular weight polyacrylate dispersant and water.

[0006] Optionally, by weight, the smoke-suppressing functional slurry is made from the following chemical raw materials by wet grinding: 5-20 parts of α-zirconium phosphate, 15-30 parts of molybdenum compound, 20-40 parts of zinc-magnesium-aluminum ternary hydrotalcite, 10-25 parts of zinc borate, 5-15 parts of montmorillonite, 5-10 parts of high molecular weight polyacrylate dispersant, and water.

[0007] Optionally, the molybdenum compound is ammonium molybdate or molybdenum trioxide.

[0008] Optionally, the particle size D50 of the powder in the smoke-suppressing functional slurry is ≤100nm.

[0009] Optionally, in the expansion system, the mass ratio of the ammonium polyphosphate, the pentaerythritol and the melamine is (15~25):(8~15):(8~12).

[0010] Optionally, the aqueous resin is an aqueous acrylic emulsion or an aqueous styrene-acrylic emulsion.

[0011] Optionally, the additives include at least one of the following: dispersant, defoamer, film-forming aid, thickener, and pH adjuster.

[0012] Secondly, embodiments of this application provide a method for preparing the water-based low-smoke intumescent fire-retardant coating for steel structures according to any one of the first aspects, the method comprising the following steps: S1. Mix water and high molecular weight ammonium polyacrylate dispersant, then add zirconium α-phosphate, molybdenum compound, zinc magnesium aluminum ternary hydrotalcite, zinc borate and montmorillonite in sequence, and perform wet grinding to obtain smoke-suppressing functional slurry; S2. Mix the smoke-suppressing functional slurry, the expansion system powder, water and additives to obtain a mixture; S3. Mix the mixture with a water-based resin to obtain the water-based low-smoke intumescent fireproof coating for steel structures.

[0013] Optionally, the wet grinding temperature is room temperature, and the wet grinding time is 1 to 4 hours.

[0014] Thirdly, embodiments of this application provide an application of the water-based low-smoke intumescent fire-retardant coating for steel structures as described in any one of the first aspects in the fire protection of steel structures.

[0015] The technical solutions provided in this application have the following advantages compared with the prior art: (1) In this application, five functional powders—zirconium α-phosphate, molybdenum compounds, zinc-magnesium-aluminum ternary hydrotalcite, zinc borate, and montmorillonite—are wet-milled together with a high molecular weight ammonium polyacrylate dispersant to form a smoke-suppressing functional slurry with a particle size D50 ≤ 100 nm. During this process, the carboxyl groups of the ammonium polyacrylate react with the Zr groups on the surface of the zirconium α-phosphate layer. 4+ Metal ions on the surfaces of hydrotalcite and zinc borate undergo coordination adsorption, forming a polymer adsorption layer on the powder surface.

[0016] This adsorption layer acts as a physical shield at room temperature, passivating the Lewis acid sites on the surface of α-zirconium phosphate and preventing unintended reactions with ammonium polyphosphate during coating storage and application, thus ensuring the chemical stability of the expansion system before heating. Studies have shown that the saturated adsorption of ammonium polyacrylate on the surface of inorganic powders can alter the surface chemical bond structure of the powders, increasing the electrostatic repulsion energy between particles, thereby significantly improving the stability of the suspension.

[0017] During the heating phase, as the temperature rises, the ammonium polyacrylate adsorbate layer gradually decomposes (200~350℃), and the acidic sites of α-zirconium phosphate are exposed in stages. At this time, ammonium polyphosphate begins to decompose to generate polyphosphoric acid, and pentaerythritol is dehydrated into carbon under the catalysis of polyphosphoric acid. The Brønsted acidic sites of α-zirconium phosphate further catalyze the condensation esterification reaction of polyphosphoric acid and pentaerythritol, promoting the formation of a cross-linked carbon network. This staged activation mechanism achieves a match between acidic catalysis and the expansion reaction process, avoiding side reactions at room temperature while ensuring catalytic efficiency at high temperatures.

[0018] (2) The five functional powders in this application work together to expand into carbon and suppress smoke.

[0019] Zirconium α-phosphate has a layered structure and Brønsted acidity. After the decomposition of the ammonium polyacrylate adsorbent layer, the exposed acidic sites of zirconium α-phosphate catalyze the esterification condensation reaction of ammonium polyphosphate with pentaerythritol, promoting the crosslinking of the char layer precursor. Its layered structure provides a reaction interface with a high specific surface area, which is beneficial to the adsorption of reactants and the anchoring of the product char layer, enhancing the density and continuity of the char layer. At the same time, the acidic sites of zirconium α-phosphate catalyze the esterification condensation reaction, promoting the orderly crosslinking of the char layer, reducing the formation of tar-like incomplete combustion products, and achieving smoke suppression from the condensed phase.

[0020] Molybdenum compounds are endothermic through redox reactions at high temperatures and simultaneously catalyze char formation. Molybdenum species can promote the decomposition of ammonium polyphosphate and the dehydration of pentaerythritol, thereby increasing the char residue rate. In addition, molybdenum compounds can capture hydrogen free radicals and hydroxyl free radicals generated during combustion at high temperatures, interrupting the gas-phase combustion chain reaction and suppressing smoke particles generated by incomplete combustion, thus achieving smoke suppression from the gas phase.

[0021] When heated, zinc-magnesium-aluminum ternary hydrotalcite undergoes endothermic decomposition, releasing interlayer water molecules and carbonate ions to form porous magnesium-aluminum-zinc composite metal oxides. This decomposition process absorbs a large amount of heat, lowering the system temperature. The generated alkaline oxides can adsorb and neutralize acidic gases produced during the expansion reaction, reducing the release of corrosive fumes. At the same time, the water vapor and carbon dioxide produced by the decomposition of hydrotalcite dilute the concentration of combustible gases and oxygen, reducing the combustion intensity and smoke generation, thus achieving multiple smoke suppression functions of endothermic cooling, acidic gas adsorption, and dilution effects.

[0022] Zinc borate melts at high temperature to form a glassy B2O3-ZnO capping layer, which covers the surface of the char layer and physically isolates the transfer of heat, oxygen and combustible gases. This glassy layer, together with the expanded char layer, forms a composite barrier structure, improving the integrity and thermal insulation performance of the char layer. At the same time, the glassy layer blocks the release of volatile degradation products into the gas phase, reducing the escape of smoke precursors. In addition, zinc borate can promote the char formation reaction and increase the residual char rate.

[0023] Montmorillonite, as a layered silicate, pyrolyzes at high temperatures to form silicon oxide. Its two-dimensional layered structure forms a physical barrier in the carbon layer, producing a tortuous path effect that hinders the escape of volatile degradation products and the penetration of oxygen. The silicon oxide and the carbon layer are combined to enhance the density and thermal stability of the carbon layer and improve its antioxidant properties, thus achieving physical barrier and smoke suppression from the condensed phase. Attached Figure Description

[0024] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0025] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 A schematic flowchart illustrating the preparation method of the water-based low-smoke intumescent fireproof coating for steel structures provided in this application embodiment; Figure 2 A physical image of the coating formed by the fire-retardant coating provided in Embodiment 1 of this application; Figure 3 A surface morphology diagram of the coating formed by the fire-retardant coating provided in Embodiment 1 of this application after combustion; Figure 4 A surface morphology diagram of the coating formed by the fire-retardant coating provided in Comparative Example 1 of this application after combustion; Figure 5 SEM image of the fire-retardant coating formed by the fire-retardant coating provided in Embodiment 1 of this application after combustion; Figure 6 SEM image of the fire-retardant coating formed by the fire-retardant coating provided in Comparative Example 1 of this application after combustion. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0028] Unless otherwise specified, the experimental methods described in the following examples are generally performed in accordance with national standards / industry standards / the contents of this publication; if there are no corresponding national standards / industry standards / the contents of this publication, they are performed in accordance with general international standards, conventional conditions or the conditions recommended by the manufacturer.

[0029] Example 1 (1) Preparation of smoke-suppressing functional slurry Weigh out 12 kg of α-zirconium phosphate, 20 kg of ammonium molybdate, 30 kg of zinc-magnesium-aluminum ternary hydrotalcite (model LSJ-3), 15 kg of zinc borate, 8 kg of montmorillonite (CAS number 1318-93-0), 6 kg of high molecular weight polyacrylate ammonium dispersant (model Dispex®AA 4040), and 55 kg of deionized water.

[0030] Deionized water and high molecular weight ammonium polyacrylate dispersant were added to the premixing tank of a sand mill and stirred at 300 rpm for 15 minutes until uniformly dispersed. Then, α-zirconium phosphate, ammonium molybdate, zinc magnesium aluminum ternary hydrotalcite, zinc borate, and montmorillonite were added sequentially. The sand mill was started and ground at 1500 rpm for 2.5 hours at room temperature, resulting in a powder particle size D50 of 85 nm, thus obtaining a smoke-suppressing slurry.

[0031] (2) Formulation of water-based low-smoke intumescent fireproof coating for steel structures Weigh out 32 kg of water-based acrylic emulsion (source: Jiangsu Runfeng Synthetic Technology Co., Ltd.), 22 kg of ammonium polyphosphate (degree of polymerization ≥1000, CAS number: 68333-79-9), 12 kg of pentaerythritol, 10 kg of melamine, 12 kg of the above-mentioned smoke-suppressing slurry, 0.5 kg of sodium hexametaphosphate, 0.3 kg of silicone defoamer (source: Shanghai Gerunning Chemical Technology Co., Ltd.), 2.5 kg of ethylene glycol butyl ether, 0.2 kg of hydroxyethyl cellulose, and deionized water to make up to 100 kg.

[0032] like Figure 1 As shown, smoke-suppressing functional slurry, ammonium polyphosphate, pentaerythritol, melamine, sodium hexametaphosphate, silicone defoamer, and some deionized water were added to a dispersion vessel and dispersed at 1000 rpm for 30 minutes until the fineness was ≤50 μm. After cooling to room temperature, water-based acrylic emulsion, ethylene glycol butyl ether, and hydroxyethyl cellulose were added and stirred evenly at 300 rpm. The viscosity was adjusted to 90 seconds using a Forecast-4 cup, filtered, and packaged to obtain a water-based low-smoke intumescent fire-retardant coating for steel structures.

[0033] Example 2 (1) Preparation of smoke-suppressing functional slurry Weigh out 8 kg of zirconium α-phosphate, 25 kg of molybdenum trioxide, 35 kg of zinc magnesium aluminum ternary hydrotalcite, 12 kg of zinc borate, 10 kg of montmorillonite, 8 kg of high molecular weight polyacrylate dispersant, and 60 kg of deionized water.

[0034] Following the preparation method of Example 1, the powder was milled for 3 hours until the particle size D50 was 92 nm to obtain the smoke-suppressing slurry.

[0035] (2) Formulation of water-based low-smoke intumescent fireproof coating for steel structures Weigh out 28 kg of water-based acrylic emulsion, 25 kg of ammonium polyphosphate, 10 kg of pentaerythritol, 8 kg of melamine, 10 kg of the above-mentioned smoke-suppressing slurry, 0.6 kg of sodium hexametaphosphate, 0.3 kg of silicone defoamer, 2.0 kg of ethylene glycol butyl ether, 0.2 kg of hydroxyethyl cellulose, and add deionized water to make up to 100 kg.

[0036] According to the preparation method of Example 1, a water-based low-smoke intumescent fireproof coating for steel structures was obtained.

[0037] Example 3 (1) Preparation of smoke-suppressing functional slurry Weigh out 16 kg of zirconium α-phosphate, 18 kg of ammonium molybdate, 25 kg of zinc magnesium aluminum ternary hydrotalcite, 20 kg of zinc borate, 6 kg of montmorillonite, 7 kg of high molecular weight polyacrylate dispersant, and 50 kg of deionized water.

[0038] Following the preparation method of Example 1, the powder was milled for 2 hours until the particle size D50 was 78 nm to obtain the smoke-suppressing slurry.

[0039] (2) Formulation of water-based low-smoke intumescent fireproof coating for steel structures Weigh out 35 kg of water-based acrylic emulsion, 18 kg of ammonium polyphosphate, 14 kg of pentaerythritol, 12 kg of melamine, 15 kg of the above-mentioned smoke-suppressing slurry, 0.5 kg of sodium hexametaphosphate, 0.3 kg of silicone defoamer, 2.5 kg of ethylene glycol butyl ether, 0.2 kg of hydroxyethyl cellulose, and add deionized water to make up to 100 kg.

[0040] According to the preparation method of Example 1, a water-based low-smoke intumescent fireproof coating for steel structures was obtained.

[0041] Comparative Example 1 This comparative example is modified from the one disclosed in Example 1 as follows: Without adding smoke-suppressing slurry, and keeping the other components unchanged, a traditional water-based intumescent fire-retardant coating is prepared.

[0042] Comparative Example 2 This comparative example is based on Example 1, with the following modifications: The smoke-suppressing slurry does not contain α-zirconium phosphate, while the other components and their amounts remain unchanged.

[0043] Comparative Example 3 This comparative example is based on Example 1, with the following modifications: Ammonium polyacrylate dispersant is not added to the smoke-suppressing slurry, while the other components and their amounts remain unchanged.

[0044] Comparative Example 4 This comparative example is based on Example 1, with the following modifications: Ammonium molybdate is not added to the smoke-suppressing slurry, while the other components and their amounts remain unchanged.

[0045] Comparative Example 5 This comparative example is based on Example 1, with the following modifications: The smoke-suppressing slurry does not contain zinc-magnesium-aluminum ternary hydrotalcite, while the other components and their dosages remain unchanged.

[0046] Comparative Example 6 This comparative example is based on Example 1, with the following modifications: Zinc borate is not added to the smoke-suppressing slurry, while the other components and their amounts remain unchanged.

[0047] Comparative Example 7 This comparative example is based on Example 1, with the following modifications: Montmorillonite is not added to the smoke-suppressing slurry, while the other components and their amounts remain unchanged.

[0048] The performance of the water-based low-smoke intumescent fire-retardant coatings for steel structures obtained in Examples 1-3 and Comparative Examples 1-7 was tested, and the results are shown in Table 1. The performance testing methods are as follows: Smoke density rating determination (GB / T 8627-2007): The coating is uniformly applied to the surface of a 25mm×25mm×6mm flat substrate, and the coating surface density is 3kg / m³. 2 After curing at room temperature for 7 days, the samples were tested. A combustion test was conducted using a smoke density chamber, and the transmittance change curve over time was recorded (4-minute test cycle). The smoke density level was calculated, and the average value of three tests was taken.

[0049] Expansion ratio determination: The coating was evenly applied to the surface of a 70mm×70mm×5mm steel plate, with a coating surface density of 3kg / m³. 2 After curing at room temperature for 7 days, the material was placed in a muffle furnace, heated to 800℃, and held at that temperature for 30 minutes. After cooling, the carbon layer thickness was measured. The expansion factor was calculated by dividing the carbon layer thickness by the initial coating thickness, and the average value of three tests was taken.

[0050] Fire resistance limit determination: The coating is evenly applied to the surface of No. 36 I-beam with a dry film thickness of 1.0 mm. After curing at room temperature for 7 days, it is placed in a fire resistance test furnace and heated according to the standard heating curve. The time when the temperature of the unexposed side reaches 540℃ is recorded, which is the fire resistance limit.

[0051] Storage stability test: The coating was placed in a sealed container and stored in a 50℃ constant temperature oven for 30 days. After being removed and brought to room temperature, the presence of stratification, precipitation, or clumping was observed. The change in fineness was measured using a scraper fineness meter to determine the storage stability level.

[0052] Table 1 Performance of Water-Based Low-Smoke Intumescent Fire-Retardant Coatings for Steel Structures As shown in Table 1, the smoke density rating of the water-based low-smoke intumescent fireproof coatings for steel structures in Examples 1-3 is 24-34, the expansion ratio is 28-35 times, the fire resistance limit is 143-165 min, and there is no sedimentation during storage.

[0053] Comparative Example 1, without the addition of smoke-suppressing slurry, showed that the smoke density level increased to 85, the expansion ratio decreased to 17 times, and the fire resistance limit decreased to 96 minutes, demonstrating that smoke-suppressing slurry is crucial for reducing smoke density and improving expansion performance.

[0054] In Comparative Example 2, without the addition of zirconium α-phosphate, the smoke density grade increased to 72, and the expansion ratio decreased to 22 times, indicating that the acidic catalytic carbonization of zirconium α-phosphate is indispensable.

[0055] Comparative Example 3, without the addition of ammonium polyacrylate dispersant, showed severe sedimentation of the slurry, making it impossible to form slabs, proving that the dispersant is the key to achieving stable co-dispersion of pentaneous powders.

[0056] In Comparative Example 4, without the addition of ammonium molybdate, the smoke density grade increased to 62, and the expansion ratio decreased to 26 times, indicating that the catalytic char formation and free radical capture functions of molybdenum compounds significantly contribute to smoke suppression.

[0057] Comparative Example 5, without the addition of zinc-magnesium-aluminum ternary hydrotalcite, showed an increase in smoke density to 74 and a decrease in expansion ratio to 24 times, demonstrating the smoke-suppressing effect of hydrotalcite's endothermic decomposition and acid gas adsorption.

[0058] Comparative Example 6, without the addition of zinc borate, showed an increase in smoke density grade to 68 and an increase in expansion ratio to 21, indicating that the glass barrier and char-promoting functions of zinc borate had the greatest impact on the expansion ratio.

[0059] Comparative Example 7, without the addition of montmorillonite, showed an increase in smoke density grade to 56 and a decrease in expansion ratio to 25, demonstrating that the two-dimensional layered physical barrier of montmorillonite plays a role in smoke suppression and char layer enhancement.

[0060] Figure 2 This is a physical image of the coating formed by the fire-retardant coating provided in Embodiment 1 of this application.

[0061] Depend on Figure 2 It can be seen that the coating of Example 1 has a uniform and smooth appearance, without obvious defects such as bubbles, pinholes, sagging, cracking and powdering, and has a good film-forming state and high surface smoothness.

[0062] Figure 3 A surface morphology diagram of the coating formed by the fire-retardant coating provided in Embodiment 1 of this application after combustion; Figure 4 The surface morphology of the coating formed by the fire-retardant coating provided in Comparative Example 1 of this application after combustion.

[0063] Depend on Figure 3 and Figure 4 It can be seen that the number of surface cracks in the coating of Example 1 is significantly reduced, demonstrating excellent high-temperature expansion into carbon and densification protection performance; the coating surface of Comparative Example 1 has a large number of through cracks, which provides a conduction path for flame and heat to quickly penetrate into the coating substrate, weakening the heat insulation and protection effect of the coating.

[0064] Figure 5 SEM image of the fire-retardant coating formed by the fire-retardant coating provided in Embodiment 1 of this application after combustion; Figure 6 SEM image of the fire-retardant coating formed by the fire-retardant coating provided in Comparative Example 1 of this application after combustion.

[0065] Depend on Figure 5 and Figure 6It can be seen that the surface structure of the expansion layer formed by the high-temperature expansion of the coating in Example 1 is dense, without large-area pores and cracks, which can effectively block the transfer of heat to the interior of the coating, significantly improve the density and high-temperature stability of the expansion layer, and thus extend the fire resistance service time of the coating in the flame environment; the expansion layer of the coating in Comparative Example 1 has large-area pore defects, and the coating is easy to decompose and remove quickly in the high-temperature environment, and cannot form an effective barrier layer, resulting in the rapid penetration of flame and heat into the substrate, making it difficult to achieve the long-term suppression of flame penetration.

[0066] The range descriptions used herein, such as numerical ranges and proportional ranges, include all possible sub-ranges and single numerical values ​​within that range. For example, the range descriptions of "1 to 6" or "1~6" cover all sub-ranges (such as 1 to 3, 2 to 5, etc.) and single numbers (such as 1, 2, 3, 4, 5, 6) between 1 and 6. Unless otherwise specified, the terms "including" and "contains" as used herein mean "including but not limited to"; relational terms such as "first" and "second" are used only to distinguish different entities or operations and do not imply an actual order or relationship; "and / or" indicates that multiple situations can exist individually or simultaneously; expressions such as "at least one," "multiple," and "at least one" refer to any combination of the corresponding objects, including combinations of single or multiple objects. The proportional relationships mentioned herein, such as mass ratios and molar ratios, should be understood as the correspondence between the first and second terms of a proportional formula, according to the order of description. The raw materials, reagents, instruments, and equipment used herein can all be obtained through commercial purchase or prepared using existing methods.

[0067] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. 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 this application. Therefore, this application 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 claimed herein.

Claims

1. A water-based, low-smoke, intumescent fire-retardant coating for steel structures, characterized in that, The coating is composed of the following chemical raw materials in parts by weight. Composition: 25-40 parts waterborne resin, 30-50 parts swelling system, 10-15 parts smoke-suppressing slurry, 2-5 parts additives, water; The expansion system is composed of ammonium polyphosphate, pentaerythritol and melamine; The smoke-suppressing slurry is made by wet grinding of zirconium α-phosphate, molybdenum compound, zinc magnesium aluminum ternary hydrotalcite, zinc borate, montmorillonite, high molecular weight polyacrylate dispersant and water.

2. The water-based low-smoke intumescent fireproof coating for steel structures according to claim 1, characterized in that, By weight, the smoke-suppressing functional slurry is made from the following chemical raw materials by wet grinding: 5-20 parts of α-zirconium phosphate, 15-30 parts of molybdenum compound, 20-40 parts of zinc-magnesium-aluminum ternary hydrotalcite, 10-25 parts of zinc borate, 5-15 parts of montmorillonite, 5-10 parts of high molecular weight polyacrylate dispersant, and water.

3. The water-based low-smoke intumescent fireproof coating for steel structures according to claim 2, characterized in that, The molybdenum compound is ammonium molybdate or molybdenum trioxide.

4. The water-based low-smoke intumescent fireproof coating for steel structures according to claim 2, characterized in that, The powder particle size D50 in the smoke-suppressing functional slurry is ≤100nm.

5. The water-based low-smoke intumescent fireproof coating for steel structures according to claim 1, characterized in that, In the expansion system, the mass ratio of the ammonium polyphosphate, the pentaerythritol and the melamine is (15~25):(8~15):(8~12).

6. The water-based low-smoke intumescent fireproof coating for steel structures according to claim 1, characterized in that, The aqueous resin is an aqueous acrylic emulsion or an aqueous styrene-acrylic emulsion.

7. The water-based low-smoke intumescent fireproof coating for steel structures according to claim 1, characterized in that, The additives include at least one of the following: dispersant, defoamer, film-forming aid, thickener, and pH adjuster.

8. A method for preparing a water-based low-smoke intumescent fire-retardant coating for steel structures according to any one of claims 1 to 7, characterized in that, The method includes the following steps: S1. Mix water and high molecular weight ammonium polyacrylate dispersant, then add zirconium α-phosphate, molybdenum compound, zinc magnesium aluminum ternary hydrotalcite, zinc borate and montmorillonite in sequence, and perform wet grinding to obtain smoke-suppressing functional slurry; S2. Mix the smoke-suppressing functional slurry, the expansion system powder, water and additives to obtain a mixture; S3. Mix the mixture with a water-based resin to obtain the water-based low-smoke intumescent fireproof coating for steel structures.

9. The preparation method of the water-based low-smoke intumescent fire-retardant coating for steel structures according to claim 8, characterized in that, The wet grinding temperature is room temperature, and the wet grinding time is 1 to 4 hours.

10. The application of a water-based low-smoke intumescent fire-retardant coating for steel structures according to any one of claims 1 to 8 in the fire protection of steel structures.

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