An intumescent carbon layer reinforced water-based fireproof coating, a preparation method and application thereof

Abstract

The application provides an intumescent carbon layer reinforced water-based fireproof paint and a preparation method and application thereof, and belongs to the technical field of fireproof paint. The application combines the high dispersibility, high-temperature stability of modified titanium dioxide, the gas phase / condensed phase flame-retardant effect of phosphorus-containing phytic acid and the porcelainizable ability of boron / silicon compounds, and is based on a traditional "ammonium polyphosphate-pentaerythritol-melamine" intumescent flame-retardant system to develop a high-performance, environmentally friendly intumescent carbon layer reinforced water-based fireproof paint. The coating sample prepared by using the water-based fireproof paint can form a high-quality intumescent carbon layer with high density during combustion, and the structure still remains complete under severe conditions such as high temperature and spray burning, can provide long-term stable fireproof protection for the base material, and can effectively inhibit the release of flammable gas and smoke particles, and improves the practical application value.

Description

Technical Field

[0001] This invention relates to the field of fire-retardant coating technology, and in particular to an intumescent char layer reinforced water-based fire-retardant coating, its preparation method, and its application. Background Technology

[0002] Steel structures possess advantages such as high strength, light weight, strong resistance to deformation, and wide applicability, making them one of the most common types of building support structures. However, steel structures inherently suffer from poor high-temperature resistance; their mechanical strength decreases rapidly with increasing temperature. In a fire environment, the load-bearing capacity of bare steel can decrease by 40% to 45% within 10 minutes, potentially leading to collapse. Therefore, it is necessary to conduct research on fire protection for steel structures to improve their fire resistance and safeguard the lives and property of the public.

[0003] Fire-retardant coatings for steel structures can effectively slow heat transfer, suppress fire spread, and reduce the severity of fires, buying valuable time for evacuation and rescue operations. Given the current improvement in environmental regulations and the implementation of low-VOC emission standards, water-based intumescent fire-retardant coatings have received widespread attention. Using water as a dispersion medium, they have low energy consumption and can significantly reduce harm to human health and the environment during production and construction. Currently, the traditional PCN intumescent flame-retardant system, composed of ammonium polyphosphate, pentaerythritol, and melamine, is still considered to have good synergistic flame-retardant effects. However, with the rapid development of new materials and new business models, the fire risks and fire loads faced by buildings are increasing. Traditional intumescent fire-retardant coatings may experience char layer damage and detachment under high-intensity heat flow or flame impact, thus affecting their fire-retardant effect. Therefore, there is an urgent need to further enhance the fire protection capabilities of fire-retardant coatings.

[0004] The density and integrity of the expanded char layer directly affect its fire resistance. Numerous scholars both domestically and internationally have conducted in-depth research on how to improve the strength and stability of the expanded char layer in fire-retardant coatings. Adding inorganic fillers (such as zinc borate, montmorillonite, aluminum hydroxide, silica, and titanium dioxide) is the simplest method and can effectively improve the thermal stability and integrity of the expanded char layer. However, to achieve better fire-retardant effects, it is often necessary to increase the amount of refractory filler introduced. Due to the differences in surface / interface properties between inorganic powder fillers and the resin matrix, excessive use may reduce their dispersibility, negatively impacting the overall performance of the coating. Generally, surface modification can be used to improve the compatibility between inorganic fillers and the matrix resin, such as introducing silane coupling agents to improve the interfacial properties of the material through chemical bonding. Chinese invention patent CN 119931433 A utilizes silane coupling agents to modify nano-titanium dioxide, combined with alkali-treated glass fiber and acid-treated expandable graphite as reinforcing fillers in fire-retardant coatings, which exhibit good char skeleton strength after ablation. However, this method involves the modification of multiple materials, making the process quite complex, and the intricate technical route affects its practical application. In recent years, researchers have focused on improving the strength of the char layer based on the ceramicization reaction of intumescent fire-retardant coatings. For example, Chinese invention patent CN 119463563 B utilizes glass powders with different melting temperatures as ceramic bodies so that the coating can form a gradient ceramicized expansion layer during a fire, providing long-term stable thermal protection for the substrate. However, this method faces the problem of compatibility between inorganic powders and the matrix, affecting the overall performance of the coating.

[0005] Furthermore, it is worth noting that the release of toxic fumes during a fire is a key factor leading to death, and traditional intumescent fire-retardant coatings are ineffective at suppressing these fumes, allowing them to easily spread. Therefore, it is necessary to develop a new technical solution for intumescent char-reinforced fire-retardant coatings to address the issues of fume release and the difficulty in balancing expansion performance with char layer strength in existing technologies. Summary of the Invention

[0006] The purpose of this invention is to provide an intumescent char layer reinforced water-based fire retardant coating, its preparation method, and its application. The intumescent char layer reinforced water-based fire retardant coating has good bonding strength, and its intumescent char layer structure remains intact even under harsh conditions such as high temperature and spraying, which can effectively suppress the release of smoke and solve the problem that the expansion performance and char layer strength of fire retardant coatings are difficult to balance in the prior art.

[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0008] This invention provides an expanded char layer reinforced water-based fire retardant coating, which, based on a total mass fraction of 100%, comprises the following raw materials:

[0009] Film-forming substance 18-30%, flame retardant 45-60%, modified titanium dioxide 3.5-12%, additives 1-5%, water 13-25%;

[0010] The method for preparing the modified titanium dioxide includes the following steps:

[0011] Titanium dioxide, a first dispersant, a boron compound, a silicon compound, and an amino compound are mixed, and the pH value is adjusted to 3-4 to perform the first modification, thereby obtaining boron / silicon modified titanium dioxide; the amino compound is γ-aminopropyltriethoxysilane.

[0012] The boron / silicon modified titanium dioxide is mixed with a second dispersant and phytic acid solution to undergo a second modification, thereby obtaining modified titanium dioxide.

[0013] Preferably, the boron compound includes one or more of trimethoxyborooxy ester, boric acid, and trimethyl borate;

[0014] The silicon compound includes one or more of tetramethyl orthosilicate, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, and tetramethyl orthosilicate;

[0015] The mass ratio of the titanium dioxide, boron compound, silicon compound, and amino compound is 8~10:1.25~2.5:0.5~1.5:1~3;

[0016] The first modification was performed at a temperature of 60-90 °C for 5-7 h.

[0017] Preferably, the mass ratio of the boron / silicon modified titanium dioxide to the phytic acid solution is 2.5~5:1;

[0018] The phytic acid solution has a mass concentration of 70%.

[0019] The second modification is performed at a temperature of 60-90 °C for 3-5 h.

[0020] Preferably, the film-forming substance includes at least one of waterborne epoxy resin, waterborne acrylic resin, waterborne polyurethane resin, waterborne silicone resin, and waterborne alkyd resin.

[0021] Preferably, when the film-forming substance is an aqueous epoxy resin, the film-forming substance further includes a curing agent; the mass ratio of the aqueous epoxy resin to the curing agent is 10~20:1.

[0022] Preferably, the flame retardant includes ammonium polyphosphate, pentaerythritol, and melamine; the mass ratio of ammonium polyphosphate, pentaerythritol, and melamine is 2.67~3.25:1~1.5:1.25~1.75.

[0023] Preferably, the additives include at least one of dispersants, thickeners, wetting agents, defoamers, and antibacterial agents.

[0024] Preferably, the dispersant comprises sodium polyacrylate; the thickener comprises a polyurethane thickener; the wetting agent comprises a nonionic wetting agent; the defoamer comprises a silicone defoamer; and the antibacterial agent comprises Kathon antibacterial agent.

[0025] This invention provides a method for preparing the expanded carbon layer reinforced water-based fire-retardant coating described in the above technical solution, comprising the following steps:

[0026] The film-forming substance is dispersed in water, and flame retardants, modified titanium dioxide, and additives are added to obtain an expanded carbon layer reinforced waterborne fireproof coating.

[0027] This invention provides the application of the expanded carbon layer reinforced water-based fire retardant coating described in the above technical solution or the expanded carbon layer reinforced water-based fire retardant coating prepared by the preparation method described in the above technical solution in fire retardant coatings for steel structures.

[0028] This invention provides an intumescent char-reinforced waterborne fire-retardant coating. It utilizes boron / silicon compounds and phytic acid grafted to modify titanium dioxide, resulting in organically modified titanium dioxide containing composite synergistic flame-retardant elements (phosphorus / boron / silicon). Not only is a boron / silicon ceramic precursor modified onto the titanium dioxide, but the introduced siloxane and phytic acid organic components also maintain good compatibility with the resin emulsion, thus improving its dispersibility in the fire-retardant coating. This invention combines the high dispersibility and high-temperature stability of modified titanium dioxide, the gas-phase / condensed-phase flame-retardant effect of phosphorus-containing phytic acid, and the ceramicization ability of boron / silicon compounds. Based on the traditional "ammonium polyphosphate-pentaerythritol-melamine" intumescent flame-retardant system, it develops a high-performance, environmentally friendly intumescent char-reinforced waterborne fire-retardant coating. The coating samples prepared using this water-based fireproof coating can form a high-quality expanded char layer with high density during combustion. Even under harsh conditions such as high temperature and spraying, its structure remains intact, providing long-term and stable fire protection for the substrate. It can also effectively suppress the release of combustible gases and smoke particles, thus enhancing its practical application value.

[0029] Boron / silicon compounds, as ceramic precursors, possess flame-retardant and fire-resistant properties, while titanium dioxide exhibits excellent heat and weather resistance, high chemical stability, and superior corrosion resistance. Phytic acid, a renewable resource, is primarily found in plant seeds, roots, and stems. Due to its molecular structure containing six phosphate groups (with a phosphorus content as high as 28%), it is an ideal material for constructing efficient and environmentally friendly flame-retardant systems. This invention, through structural design, utilizes boron / silicon ceramic precursors and titanium dioxide to synergistically construct a multiphase ceramic, achieving surface modification of titanium dioxide by the boron / silicon ceramic precursors and phytic acid. This enhances the fire resistance of fire-retardant coatings, expanding the utilization pathways of biomass resources and effectively strengthening the expanded char layer of the fire-retardant coating.

[0030] This invention addresses how to improve the char layer strength and fire resistance of intumescent fire-retardant coatings for steel structures. Based on the traditional "ammonium polyphosphate-pentaerythritol-melamine" intumescent flame-retardant system, it uses water-based resin as the film-forming material and organically modified titanium dioxide containing boron / silicon ceramic precursors and phytic acid as the building blocks of the intumescent char layer strengthening system to develop a high-performance, environmentally friendly fire-retardant coating. Surface modification of titanium dioxide enhances its interfacial bonding force within the coating system and improves its compatibility with the resin matrix. Modified titanium dioxide, as a multifunctional synergist, can utilize phosphorus free radicals generated during the thermal decomposition of phytic acid to capture hydroxyl free radicals produced during combustion, thus blocking the combustion chain reaction (gas-phase flame retardancy). Furthermore, the coating expands upon heating in the presence of fire; as the temperature rises, the boron / silicon ceramic precursor participates in the formation of the intumescent ceramic char layer and increases its strength. On the other hand, based on the good thermal stability of titanium dioxide, it reacts with the acid source at high temperature to form high-temperature resistant titanium pyrophosphate (TiP2O7), which is embedded in the matrix, thereby enhancing the expanded carbon layer structure (condensed phase flame retardancy), which is more conducive to providing long-lasting and durable fire protection for the substrate.

[0031] Compared with existing intumescent flame retardant systems, the intumescent char layer-reinforced flame retardant system based on modified titanium dioxide provided by this invention can achieve effective reinforcement of the intumescent char layer without the introduction of other ceramic fillers. The modified titanium dioxide used in this invention can be uniformly dispersed in the system. During combustion, the coating can generate a dense and continuous phosphorus-boron / silicon-carbon structure, and the high-temperature resistant component TiP2O7 is embedded in it, which increases the amount of char residue after ablation, can block heat transfer and effectively reduce the release of combustible gases and flue gas particles.

[0032] Furthermore, the preparation process of the modified titanium dioxide in this invention is simple, and it incorporates phytic acid, a renewable biomass resource. The raw materials used in the expanded carbon layer-reinforced water-based fire-retardant coating of this invention are environmentally friendly, low in toxicity, and inexpensive. The production process is consistent with that of traditional fire-retardant coatings, with low energy consumption, making it easy to commercialize and achieve industrial application. Attached Figure Description

[0033] Figure 1 The images show the FT-IR (a) and XPS (b) spectra of TiO2, BSTi, and PBSTi in Example 1.

[0034] Figure 2 The TG curves for TiO2, BSTi, and PBSTi in Example 1 are shown.

[0035] Figure 3 Images showing the dispersion state of TiO2 and PBSTi in Example 1;

[0036] Figure 4 The bonding strength of the fire-retardant coatings in Examples 1-3 and Comparative Examples 1-2;

[0037] Figure 5 The TG curves of the fire-retardant coatings in Examples 1-3 and Comparative Examples 1-2 are shown.

[0038] Figure 6 The fire resistance curves of the fire-retardant coatings and steel plates in Examples 1-3 and Comparative Examples 1-2 are shown.

[0039] Figure 7 The expansion ratios of the fire-retardant coatings in Examples 1-3 and Comparative Examples 1-2 are shown.

[0040] Figure 8 These are test images of the expanded carbon layer strength of the coatings obtained in Example 2 and Comparative Example 1 after ablation.

[0041] Figure 9 The heat release rate (a), total heat release (b), and total smoke generation curves (c) of the coatings obtained in Example 2 and Comparative Example 1 after ablation are shown.

[0042] Figure 10 The coatings obtained in Example 2 and Comparative Example 1 are in the expanded carbon layer state after ablation. Detailed Implementation

[0043] In this invention, unless otherwise specified, the raw materials or reagents required for preparation are all commercially available products well known to those skilled in the art.

[0044] This invention provides an expanded char layer reinforced water-based fire retardant coating, which, based on a total mass fraction of 100%, comprises the following raw materials:

[0045] Film-forming substance 18-30%, flame retardant 45-60%, modified titanium dioxide 3.5-12%, additives 1-5%, water 13-25%;

[0046] The method for preparing the modified titanium dioxide includes the following steps:

[0047] Titanium dioxide, a first dispersant, a boron compound, a silicon compound, and an amino compound are mixed, and the pH value is adjusted to 3-4 to perform the first modification, thereby obtaining boron / silicon modified titanium dioxide; the amino compound is γ-aminopropyltriethoxysilane.

[0048] The boron / silicon modified titanium dioxide is mixed with a second dispersant and phytic acid solution to undergo a second modification, thereby obtaining modified titanium dioxide.

[0049] Based on the total mass fraction of the expanded carbon layer reinforced water-based fire retardant coating being 100%, the raw materials for preparing the expanded carbon layer reinforced water-based fire retardant coating provided by the present invention include 18-30% film-forming substances, preferably 20.4-25%, and more preferably 21.1-21.9%.

[0050] In this invention, the film-forming substance preferably includes at least one selected from waterborne epoxy resin, waterborne acrylic resin, waterborne polyurethane resin, waterborne silicone resin, and waterborne alkyd resin. When the film-forming substance is two or more of the above, this invention does not have a special limitation on the ratio of different types of film-forming substances, and any ratio is acceptable. This invention does not have a special limitation on the specific specifications and source of the film-forming substance; commercially available products well known in the art are acceptable.

[0051] When the film-forming substance is an aqueous epoxy resin, the film-forming substance preferably also includes a curing agent; the mass ratio of the aqueous epoxy resin to the curing agent is preferably 10~20:1. This invention does not have a specific limitation on the type of curing agent; any commercially available curing agent corresponding to the desired epoxy resin is acceptable.

[0052] Based on the total mass fraction of the expanded carbon layer reinforced water-based fire retardant coating being 100%, the raw materials for preparing the expanded carbon layer reinforced water-based fire retardant coating provided by the present invention include 45-60% flame retardant, more preferably 51.5-55.5%, and even more preferably 52.9-53.4%.

[0053] In this invention, the flame retardant preferably includes ammonium polyphosphate, pentaerythritol, and melamine (a traditional intumescent flame retardant system); the mass ratio of ammonium polyphosphate, pentaerythritol, and melamine is preferably 2.67~3.25:1~1.5:1.25~1.75, more preferably 2.8~3.2:1~1.3:1.28~1.5, and even more preferably 3:1:1.3~1.6.

[0054] Based on the total mass fraction of the expanded carbon layer reinforced waterborne fire retardant coating being 100%, the raw materials for preparing the expanded carbon layer reinforced waterborne fire retardant coating provided by the present invention include 3.5~12% modified titanium dioxide, more preferably 3.9~11.5%, and even more preferably 7.5~10.9%.

[0055] In this invention, the method for preparing the modified titanium dioxide includes the following steps:

[0056] Titanium dioxide, a first dispersant, a boron compound, a silicon compound, and an amino compound are mixed, and the pH value is adjusted to 3-4 to perform the first modification, thereby obtaining boron / silicon modified titanium dioxide; the amino compound is γ-aminopropyltriethoxysilane.

[0057] The boron / silicon modified titanium dioxide is mixed with a second dispersant and phytic acid solution to undergo a second modification, thereby obtaining modified titanium dioxide.

[0058] In this invention, the boron compound preferably includes one or more of trimethoxyborooxy ester, boric acid, and trimethyl borate; when the boron compound is two or more of the above, this invention does not have a special limitation on the ratio of different types of boron compounds, and any ratio is acceptable.

[0059] In this invention, the silicon compound preferably includes one or more of tetraethyl orthosilicate, vinyltriethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, and tetramethyl orthosilicate; when the silicon compound is two or more of the above, this invention does not have a special limitation on the ratio of different types of silicon compounds, and any ratio is acceptable.

[0060] In this invention, the mass ratio of titanium dioxide, boron compound, silicon compound and amino compound is preferably 8~10:1.25~2.5:0.5~1.5:1~3, more preferably 9~10:1.5~2.4:1.0~1.5:2~3, and even more preferably 10:2.5:1.5:3.

[0061] This invention utilizes the electrostatic bonding between the amino group in the amino compound (γ-aminopropyltriethoxysilane) and the phosphorus hydroxyl group in phytic acid to modify the surface of titanium dioxide with phytic acid. At the same time, the amino compound also provides silicon.

[0062] In this invention, the first dispersant is preferably an anhydrous ethanol-water mixture; the mass ratio of the anhydrous ethanol to water is preferably 1:2. This invention does not impose any special limitation on the amount of the first dispersant, as long as the material is completely dispersed.

[0063] In this invention, titanium dioxide is preferably dispersed in a first dispersant, followed by the addition of a boron compound, a silicon compound, and an amino compound. The pH of the system is adjusted to 3-4, more preferably 3.5, and the mixture is magnetically stirred at room temperature for 3-3.5 h before the first modification is performed.

[0064] The present invention preferably uses hydrochloric acid solution to adjust the pH value; the present invention does not have a special limitation on the concentration of the hydrochloric acid solution, and can adjust it to achieve the required pH value as needed.

[0065] In this invention, the temperature of the first modification is preferably 60~90 °C, more preferably 70~85 °C, and the time is preferably 5~7 h, more preferably 6 h.

[0066] After completing the first modification, the present invention preferably filters and washes the obtained product three times to obtain boron / silicon modified titanium dioxide, denoted as BSTi.

[0067] In this invention, the mass concentration of the phytic acid solution is preferably 70%, and the mass ratio of the boron / silicon modified titanium dioxide to the phytic acid solution is preferably 2.5~5:1, more preferably 2.86~3.4:1.

[0068] In this invention, the second dispersant is preferably an anhydrous ethanol-water mixture, wherein the mass ratio of the anhydrous ethanol to the water is preferably 1:2.

[0069] In this invention, boron / silicon modified titanium dioxide is preferably dispersed in a second dispersant, and phytic acid solution is added to perform a second modification.

[0070] In this invention, the temperature for the second modification is preferably 60-90 °C, more preferably 70-85 °C, and the time is preferably 3-5 h, more preferably 4 h.

[0071] After completing the second modification, the present invention preferably filters and washes the obtained product three times, then dries it to obtain phosphorus / boron / silicon modified titanium dioxide, denoted as PBSTi.

[0072] The modified titanium dioxide described in this invention is a boron / silicon ceramic precursor and phytic acid-modified titanium dioxide.

[0073] Based on the total mass fraction of the expanded carbon layer reinforced water-based fire retardant coating being 100%, the raw materials for preparing the expanded carbon layer reinforced water-based fire retardant coating provided by the present invention include 1-5% additives, more preferably 2.1-2.2%.

[0074] In this invention, the additives preferably include at least one of dispersants, thickeners, wetting agents, defoamers, and antibacterial agents.

[0075] In this invention, the dispersant preferably comprises sodium polyacrylate; the thickener preferably comprises a polyurethane thickener; the wetting agent preferably comprises a nonionic wetting agent; the defoamer preferably comprises an organosilicone defoamer; and the antibacterial agent preferably comprises Kathon antibacterial agent. This invention does not impose any particular limitations on the specific specifications of the dispersant, thickener, wetting agent, defoamer, and antibacterial agent; commercially available products corresponding to the above-mentioned types well known in the art are acceptable.

[0076] In this invention, taking the total mass fraction of the expanded carbon layer reinforced water-based fireproof coating as 100%, the mass percentage content of the dispersant is preferably 0.5-0.65%, more preferably 0.56-0.62%; the mass percentage content of the thickener is preferably 0.4-0.6%, more preferably 0.5-0.52%; the mass percentage content of the wetting agent is preferably 0.25-0.45%, more preferably 0.33-0.37%; the mass percentage content of the defoamer is preferably 0.35-0.6%, more preferably 0.44-0.52%; and the mass percentage content of the antibacterial agent is preferably 0.22-0.35%, more preferably 0.26-0.31%.

[0077] Based on the total mass fraction of the expanded carbon layer reinforced water-based fire retardant coating being 100%, the raw materials for preparing the expanded carbon layer reinforced water-based fire retardant coating provided by the present invention include 13-25% water, more preferably 15.1-16.3%, and even more preferably 15.7%.

[0078] This invention provides a method for preparing the expanded carbon layer reinforced water-based fire-retardant coating described in the above technical solution, comprising the following steps:

[0079] The film-forming substance is dispersed in water, and flame retardants, modified titanium dioxide, and additives are added to obtain an expanded carbon layer reinforced waterborne fireproof coating.

[0080] The present invention preferably disperses the film-forming substance in water (1000 rpm, 5 min), adds the flame retardant and modified titanium dioxide to the obtained dispersion, and adds the additives under stirring conditions (1500 rpm, 30 min) to obtain an expanded carbon layer reinforced waterborne fireproof coating.

[0081] This invention provides the application of the expanded carbon layer reinforced water-based fire-retardant coating described in the above-described technical solutions, or the expanded carbon layer reinforced water-based fire-retardant coating prepared by the preparation method described in the above-described technical solutions, in fire-retardant coatings for steel structures. This invention does not impose any particular limitation on the method of application; any method well-known in the art can be used.

[0082] The specific embodiments of the present invention are described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0083] Unless otherwise specified, the experimental methods described in the various embodiments of this invention are conventional methods; unless otherwise specified, the reagents and raw materials described below are all commercially available.

[0084] Example 1

[0085] This embodiment provides a method for preparing an expanded carbon layer reinforced water-based fire-retardant coating, comprising the following steps:

[0086] (1) Preparation of modified titanium dioxide

[0087] 10 g of titanium dioxide (TiO2, R-930, Langfang Lanke Chemical Co., Ltd.) was dispersed in a mixed solution containing anhydrous ethanol (130 g) and deionized water (260 g). Then, 2.5 g of trimethoxyboroxyester (Shanghai Maclean Biochemical Technology Co., Ltd.), 1.5 g of tetraethyl orthosilicate (Shanghai Maclean Biochemical Technology Co., Ltd.), and 3 g of γ-aminopropyltriethoxysilane (Shanghai Maclean Biochemical Technology Co., Ltd.) were added. The pH of the system was adjusted to 3.5 using a 20% hydrochloric acid solution. The mixture was magnetically stirred at room temperature for 3 h, and then heated to 85 °C for another 6 h. After filtration and washing three times, boron / silicon modified titanium dioxide was obtained, denoted as BSTi.

[0088] 10 g of the boron / silicon modified titanium dioxide was dispersed in a mixed solution containing anhydrous ethanol (130 g) and deionized water (260 g), 3.5 g of phytic acid solution (70% by mass, Shanghai Aladdin Biochemical Technology Co., Ltd.) was added, and the mixture was magnetically stirred at 85 °C for 4 h. After filtration, washing three times, and drying, phosphorus / boron / silicon modified titanium dioxide was obtained, denoted as PBSTi.

[0089] (2) Preparation of expanded carbon layer reinforced waterborne fireproof coating

[0090] First, 32 g of aqueous epoxy resin emulsion (ALQ-RE 2156, Tianjin Aoluoqi Chemical Technology Co., Ltd.) was dispersed in 25 g of deionized water (1000 rpm, 5 min). Then, 48 g of ammonium polyphosphate (Exolit AP422, Clariant Chemical Technology (Shanghai) Co., Ltd.), 16 g of pentaerythritol (Charmor PM40, Perstor (Shanghai) Chemical Products Trading Co., Ltd.), 21 g of melamine (Mingyue, Shandong Mingyue Chemical Co., Ltd.), and 6 g of the modified titanium dioxide prepared in step (1) above were added to the above solution. Under stirring conditions (1500 rpm, 30 min), 1 g of dispersant (SC-860, Aohanshengchuan Chemical (Beijing) Co., Ltd.), 0.8 g of thickener (UH-752, Adico (Shanghai) Trading Co., Ltd.), 0.5 g of wetting agent (SC-407, Aohanshengchuan Chemical (Beijing) Co., Ltd.), and 0.8 g of thickener were added. Add 0.4 g of defoamer (BWF-WM906, Jinan Yuanyang Chemical Co., Ltd.), 0.4 g of antibacterial agent (SC-189, Aohanshengchuan Chemical (Beijing) Co., Ltd.), and finally add 1.6 g of water-based epoxy curing agent (ALQ-354, Tianjin Aoluoqi Chemical Technology Co., Ltd.) to obtain an expanded carbon layer reinforced water-based fireproof coating.

[0091] Example 2

[0092] (1) The preparation of modified titanium dioxide is the same as in Example 1.

[0093] (2) The preparation of the expanded carbon layer reinforced water-based fireproof coating is the same as in Example 1, except that the amount of modified titanium dioxide added in step (1) is 12 g.

[0094] Example 3

[0095] (1) The preparation of modified titanium dioxide is the same as in Example 1.

[0096] (2) The preparation of the expanded carbon layer reinforced water-based fireproof coating is the same as in Example 1, except that the amount of modified titanium dioxide added in step (1) is 18 g.

[0097] Example 4

[0098] (1) The preparation of modified titanium dioxide is the same as in Example 1.

[0099] (2) The preparation of the expanded carbon layer reinforced waterborne fireproof coating is the same as in Example 1, except that the waterborne epoxy resin is replaced with waterborne acrylic resin (FX-9116, Nantong Fangxin Chemical Co., Ltd.), and no waterborne epoxy curing agent is required.

[0100] Example 5

[0101] (1) The preparation of modified titanium dioxide is the same as in Example 1.

[0102] (2) The preparation of the expanded carbon layer reinforced waterborne fireproof coating is the same as in Example 1, except that the waterborne epoxy resin is replaced with waterborne polyurethane resin (SEAPUR 50G33, Guangdong Xidun New Material Technology Co., Ltd.) and waterborne silicone resin (VR2402, Shenzhen Weiteli Environmental Protection Materials Co., Ltd.), wherein the mass ratio of waterborne polyurethane resin to waterborne silicone resin is 1:1, and no waterborne epoxy curing agent is required.

[0103] Example 6

[0104] (1) Preparation of modified titanium dioxide

[0105] 10 g of titanium dioxide (R-930, Langfang Lanke Chemical Co., Ltd.) was dispersed in a mixed solution containing anhydrous ethanol (130 g) and deionized water (260 g). Then, 2.4 g of trimethyl borate (Shandong Xinshunli Chemical Technology Co., Ltd.), 1.6 g of tetramethyl orthosilicate (Shandong Rongsheng New Materials Co., Ltd.), and 3 g of γ-aminopropyltriethoxysilane (Shanghai Maclean Biochemical Technology Co., Ltd.) were added. The pH of the system was adjusted to 4 using a 20% hydrochloric acid solution. The mixture was magnetically stirred at room temperature for 3.5 h, and then heated to 90 °C for 5 h. After filtration and washing three times, boron / silicon modified titanium dioxide was obtained.

[0106] The above boron / silicon modified titanium dioxide (12 g) was dispersed in a mixed solution containing anhydrous ethanol (130 g) and deionized water (260 g), 3.5 g of phytic acid solution (Shanghai Aladdin Biochemical Technology Co., Ltd.) was added, and the mixture was magnetically stirred at 85 °C for 4 h. After filtration, washing three times, and drying, phosphorus / boron / silicon modified titanium dioxide was obtained.

[0107] (2) The preparation of the expanded carbon layer reinforced water-based fireproof coating is the same as in Example 2.

[0108] Example 7

[0109] (1) The preparation of modified titanium dioxide is the same as in Example 6, except that trimethyl borate is replaced with boric acid (Jinan Century Tongda Chemical Co., Ltd.).

[0110] (2) Preparation of expanded carbon layer reinforced waterborne fireproof coating

[0111] First, 35 g of waterborne acrylic resin (FX-9116, Nantong Fangxin Chemical Co., Ltd.) was dispersed in 25 g of deionized water (1000 rpm, 5 min). Then, 45 g of ammonium polyphosphate (Exolit AP422, Clariant Chemical Technology (Shanghai) Co., Ltd.), 15 g of pentaerythritol (Charmor PM40, Perstor (Shanghai) Chemical Products Trading Co., Ltd.), 25 g of melamine (Mingyue, Shandong Mingyue Chemical Co., Ltd.), and 12 g of the modified titanium dioxide prepared in step (1) above were added to the above solution. Under stirring conditions (1500 rpm, 30 min), 0.9 g of dispersant (SC-860, Aohanshengchuan Chemical (Beijing) Co., Ltd.), 0.8 g of thickener (UH-752, Adico (Shanghai) Trading Co., Ltd.), 0.6 g of wetting agent (SC-407, Aohanshengchuan Chemical (Beijing) Co., Ltd.), 0.7 g of defoamer (BWF-WM906, Jinan Yuanyang Chemical Co., Ltd.), and 0.5 g of other ingredients were added. g antibacterial agent (SC-189, Aohanshengchuan Chemical (Beijing) Co., Ltd.), which yields an expanded carbon layer reinforced water-based fireproof coating.

[0112] Comparative Example 1

[0113] The preparation of the water-based fire-retardant coating is the same as in Example 2, except that no modified titanium dioxide or titanium dioxide is added to the system.

[0114] Comparative Example 2

[0115] The preparation of the water-based fire-retardant coating is the same as in Example 2, except that the modified titanium dioxide is replaced with unmodified titanium dioxide raw material, and the amount added is 12 g.

[0116] Structural characterization

[0117] 1) The chemical structures of titanium dioxide before and after modification in Example 1 were characterized by FT-IR and XPS, and the results are as follows: Figure 1 As shown.

[0118] Figure 1 The images show the FT-IR (a) and XPS (b) spectra of TiO2, BSTi, and PBSTi from Example 1; Figure 1 As can be seen in (a), the FT-IR spectrum of boron / silicon modified titanium dioxide (BSTi) at 2946 cm⁻¹... -1 1520 cm -1 and 800 cm -1 The presence of stretching vibration peaks at 920 cm⁻¹, attributed to CH, bending vibration peaks of NH, and stretching vibration peaks of Si-C in γ-aminopropyltriethoxysilane, indicates that γ-aminopropyltriethoxysilane has been successfully grafted onto the titanium dioxide surface. Furthermore, the presence of peaks at 920 cm⁻¹ further supports this finding. -1The absorption peak at 3406 cm⁻¹ corresponds to that of Si-OB, indicating that boron (B) has also been modified onto the surface of titanium dioxide. The FT-IR spectrum of phosphorus / boron / silicon modified titanium dioxide (PBSTi) shows an absorption peak at 3406 cm⁻¹. -1 The stretching vibration peak at 1520 cm⁻¹ is enhanced, while the peak at 1520 cm⁻¹ is also enhanced. -1 The weakening of the bending vibration absorption peak attributed to NH indicates that the hydroxyl groups in phytic acid and the amino groups in γ-aminopropyltriethoxysilane form ionic bonds through electrostatic bonding. From the XPS spectrum of BSTi ( Figure 1 As shown in (b)), compared to unmodified titanium dioxide, the introduction of trimethoxyboroxyester and γ-aminopropyltriethoxysilane resulted in new peaks at 192.1 eV and 401.8 eV, respectively, attributable to B and N elements. Furthermore, the XPS spectrum of PBSTi was nearly identical to that of BSTi, except for the appearance of a new peak at 133.5 eV attributable to P, indicating that phytic acid had been successfully modified onto the titanium dioxide surface.

[0119] 2) The thermal stability of titanium dioxide before and after modification in Example 1 was characterized by thermogravimetric analysis (TG). The thermogravimetric curves are shown below. Figure 2 As shown. Figure 2 The TG curves for TiO2, BSTi, and PBSTi in Example 1 are shown below. Figure 2 As shown, unmodified titanium dioxide exhibited almost no weight loss within the test range, demonstrating good thermal stability of inorganic materials. After introducing trimethoxyboronyl ester, tetraethyl orthosilicate, and γ-aminopropyltriethoxysilane, the BSTi sample showed some thermal weight loss, with a mass loss rate of approximately 5.5% after heating to 800 °C, which can be mainly attributed to the thermal degradation of the organic components. Further introduction of phytic acid increased the thermal weight loss rate of the PBSTi sample to 6.1%, but it remained at a low level, mainly due to the inorganic components. These results further demonstrate the successful preparation of phosphorus / boron / silicon modified titanium dioxide samples.

[0120] 3) The modified titanium dioxide (TiO2, PBSTi) from Example 1 were dispersed in deionized water by ultrasonication (100 W, 20 min), and their dispersion was observed using a metallographic polarizing microscope (WMJ-9590, Shanghai Presys Instruments Co., Ltd.). Figure 3 As shown, after ultrasonic dispersion, TiO2 exhibited significant aggregation in deionized water. In contrast, the organically modified PBSTi sample showed better dispersion under the same conditions, with a marked improvement in aggregation, providing a good foundation for further preparation of expanded carbon layer-reinforced waterborne fire-retardant coatings.

[0121] Performance testing

[0122] 1) The bonding strength of water-based fire retardant coatings was tested in accordance with GB 14907-2018. The bonding strength between the expanded carbon layer reinforced water-based fire retardant coating and the steel plate was evaluated by pull-out test.

[0123] Figure 4 The bonding strength of the fire-retardant coatings in Examples 1-3 and Comparative Examples 1-2; such as Figure 4 As shown, the bond strength of Comparative Example 1 was 0.58 MPa. However, with the gradual increase in the amount of modified titanium dioxide introduced into the system, the bond strengths of Examples 1, 2, and 3 decreased to 0.56 MPa, 0.46 MPa, and 0.38 MPa, respectively. This is mainly because the increase in the amount of inorganic nanoparticles reduced the cohesive force of the system, thus affecting the adhesion performance between the resin matrix and the substrate. It is worth noting that compared with Example 2, the bond strength of the fire retardant coating (Comparative Example 2) with the same amount of unmodified titanium dioxide decreased to 0.35 MPa. This can be attributed to the improved dispersibility of modified titanium dioxide in the resin matrix, while the unmodified titanium dioxide exhibited partial agglomeration in the resin matrix, thus affecting its film-forming continuity and resulting in a decrease in bond strength.

[0124] 2) Thermogravimetric analysis of water-based fire-retardant coatings: STA 449F5 thermal analyzer, heating rate of 20 ℃ / min, temperature range of 40~800 ℃, nitrogen atmosphere.

[0125] Figure 5 The TG curves of the fire-retardant coatings in Examples 1-3 and Comparative Examples 1-2 are shown; from Figure 5The TG curve of the fire-retardant coating under a nitrogen atmosphere shows that with the increase of the amount of modified titanium dioxide introduced into the system, the heat resistance stability of the fire-retardant coating gradually increases, and the residual char content is also significantly improved. The fire-retardant coating prepared in this invention is based on the traditional "ammonium polyphosphate-pentaerythritol-melamine" intumescent flame-retardant system, and its thermal decomposition process is quite similar. After the coating is gradually heated, the moisture in the system gradually evaporates, and small molecules decompose. As the temperature further increases, the thermal degradation of ammonium polyphosphate to produce acid, the melting, dehydration, carbonization, and cross-linking of pentaerythritol, and the decomposition of melamine to produce gas are involved, thereby forming an intumescent char layer. The temperature range of 510~800 ℃ can be attributed to the further decomposition of the intumescent char layer at high temperature, with relatively little mass loss. The introduction of organic modified titanium dioxide is conducive to the formation of a higher quality intumescent char layer in this stage, producing a good synergistic effect with the "PCN" intumescent flame-retardant system. The residual mass rates of Examples 1, 2, and 3 were 43.5%, 47.6%, and 52.8%, respectively, which were significantly higher than the 30.5% residual mass rate of Comparative Example 1. The higher char content is beneficial for improving the fire resistance of the intumescent fire-retardant coating. It is worth noting that compared to Example 2, the residual mass rate of the fire-retardant coating with the same amount of unmodified titanium dioxide (Comparative Example 2) was 48.5%, slightly higher. This is mainly because the modified titanium dioxide is coated with organic components (silicon compounds, γ-aminopropyltriethoxysilane, and phytic acid), which undergoes pyrolysis after high-temperature ablation, leading to an increase in the overall heat loss of the fire-retardant coating system.

[0126] 3) Fire resistance test: First, an expanded carbon layer reinforced water-based fire retardant coating was brushed onto the steel plate surface (coating thickness: 1.5 mm). After it was completely dry, it was fixed to an iron stand and ignited using a methane spray gun, with a flame distance of 8.5 cm from the steel plate. A K-type thermocouple was attached to the back of the steel plate, and the back temperature was monitored in real time using a data acquisition device. The results are shown in […]. Figure 6 .

[0127] Figure 6 The fire resistance curves of the fire-retardant coatings and steel plates in Examples 1-3 and Comparative Examples 1-2 are shown; from Figure 6As can be seen, the back temperature of the uncoated steel plate reached 510 ℃ after being continuously sprayed with methane for 20 minutes, while the back temperatures of the steel plates coated with fire-retardant coatings from Comparative Example 1, Examples 1, 2, and 3 reached 256.5 ℃, 262.7 ℃, 266.9 ℃, and 299.8 ℃ respectively after the same spraying time. It can be observed that as the amount of modified titanium dioxide in the system increases, the thermal insulation performance of the fire-retardant coating decreases slightly. This is mainly because the introduction of inorganic fillers increases the foaming viscosity of the expansion system, which inhibits the expansion ratio of the coating, thus affecting the thermal insulation performance. Compared with Comparative Example 2, which added the same amount of unmodified titanium dioxide (back temperature 271.9 ℃), the steel plate coated by Example 2 had a lower back temperature. The reason for this may be that the modified titanium dioxide surface is modified with flame retardant elements such as P, B, and Si. After high-temperature calcination, it can work together with the intumescent flame retardant system and refractory filler to form a high-quality carbon layer (forming a ceramic body), thereby improving the fire resistance and heat insulation performance of the coating.

[0128] 4) Measure the expansion height of the fire-retardant coating after ablation by the methane spray gun using a ruler. Calculate the expansion ratio based on the ratio of the expanded height to the initial coating thickness (1.5 mm). For example, if the initial coating thickness is 1.5 mm and the expanded thickness after ablation is A, then the expansion ratio is A / 1.5. 100%.

[0129] Figure 7 The expansion ratios of the fire-retardant coatings in Examples 1-3 and Comparative Examples 1-2 are shown; from Figure 7 It can be seen that the trend of the expansion ratio of the prepared expanded char layer reinforced waterborne fireproof coating is consistent with the combustion back temperature test results. With the increase of the amount of modified titanium dioxide introduced, the expansion ratio decreased from 24.3% in Comparative Example 1 to 17.6% in Example 3. This is because the coating generates a dense phosphorus-silicon / boron-carbon structure during combustion, and high-temperature resistant components such as titanium pyrophosphate are embedded in it. The excessively high proportion of inorganic fillers in the system will limit the expansion of non-combustible gases on the char layer, resulting in a decrease in the expansion ratio, but it still exhibits good fireproof and heat insulation performance. It is worth noting that the expansion ratio of Example 2 is slightly higher than that of Comparative Example 2, which may be due to the higher dispersibility of modified titanium dioxide and the gas generated by the thermal decomposition of its surface organic components (such as silicon compounds, γ-aminopropyltriethoxysilane, phytic acid), which to some extent improves the expansion capacity of the char layer.

[0130] 5) Place a 100 g weight vertically on the surface of the expanded carbon layer of the fireproof coating after it has been eroded by a methane spray gun during the fire resistance test in step 3) above, and observe whether the expanded carbon layer can withstand the weight of the weight.

[0131] Figure 8The images show the strength test results of the expanded carbon layer after ablation of the coatings (1.5 mm thick) obtained in Example 2 and Comparative Example 1; from... Figure 8 It can be observed that the expanded carbon layer of the coating obtained in Example 2, after ablation, exhibits high strength and can withstand a 100 g weight without collapsing or breaking. In contrast, the expanded carbon layer of the coating obtained in Comparative Example 1, after ablation, cannot withstand this weight, and the weight sinks into the expanded carbon layer. This further demonstrates that the introduction of modified titanium dioxide can significantly improve the strength of the expanded carbon layer of the fire-retardant coating, which is beneficial for better protecting the substrate material in actual fire scenarios. In summary, although Comparative Example 1 has relatively high bond strength and expansion ratio, its expanded carbon layer has very low strength and is easily damaged by heat flow and external impact, thus losing its fire-resistant protection capability.

[0132] 6) The combustion behavior of fire-retardant coating (100 mm × 100 mm × 0.6 mm) was analyzed using an FTT cone calorimeter according to ISO 5660-1, with a thermal radiation power of 35 kW / m². 2 .

[0133] Figure 9 The graphs show the heat release rate (a), total heat release (b), and total smoke generation curves (c) of the fire-retardant coatings obtained in Example 2 and Comparative Example 1 after ablation. Figure 9 It can be seen that the coating obtained in Comparative Example 1 reaches a peak heat release rate of 103.5 kW / m² at 47 s. 2 The coating obtained in Example 2 achieved a peak heat release rate of 89.6 kW / m² at 56 s. 2 This indicates that modified titanium dioxide can provide good fire protection in fire-retardant coatings. Furthermore, Comparative Example 1 showed that the total heat release and total smoke generation of the coating were 4.3 MJ / m³. 2 and 0.28 m 2 In Example 2, the total heat release and total smoke generation of the coating were reduced to 3.6 MJ / m³. 2 and 0.25 m 2 This can be mainly attributed to the fact that after the modified titanium dioxide is introduced into the intumescent flame retardant system, it can generate a denser, continuous intumescent char layer during combustion, which hinders heat transfer and effectively reduces the release of combustible gases and flue gas particles.

[0134] 7) The microstructure of the residual char of the expanded char layer reinforced waterborne fireproof coating after ablation was studied using scanning electron microscopy (SEM).

[0135] Figure 10 The expanded carbon layer state of the coatings obtained in Example 2 and Comparative Example 1 after ablation; from Figure 10As can be seen, the expanded carbon layer of the coating obtained in Example 2 is loose and incomplete after ablation, with large pores. In contrast, the expanded carbon layer of the coating obtained in Comparative Example 1 exhibits good continuity and integrity after ablation, with no obvious pores and a dense surface, serving as a good barrier to isolate heat and flue gas transfer. This is mainly because the inorganic filler containing ceramic precursors participates in the formation of the carbon layer skeleton, and the titanium dioxide and ammonium polyphosphate or its degradation products, after complete combustion, form high-phosphorus titanium phosphate which is embedded in the matrix, thus strengthening the expanded carbon layer structure and providing more effective and durable fire-resistant protection for the substrate.

[0136] For Examples 4 and 5, after replacing the film-forming material, the bonding strength, expansion ratio, and fire resistance of the resulting intumescent fire-retardant coatings did not change significantly compared to Example 1. The bonding strength of Example 4 was 0.55 MPa, the expansion ratio was 23%, and the back temperature after a 20-minute fire resistance test was 261.5 ℃; the bonding strength of Example 5 was 0.51 MPa, the expansion ratio was 21.5%, and the back temperature after a 20-minute fire resistance test was 259.6 ℃. This indicates that the choice of film-forming material has a relatively small impact on the performance of the fire-retardant coating.

[0137] The intumescent fire-retardant coating obtained in Example 6 had a bond strength of 0.48 MPa, an expansion ratio of 20.2%, and a back temperature of 269.7 °C after a 20-minute fire resistance test. Compared with Example 2, the intumescent fire-retardant coating obtained in Example 7 had a bond strength of 0.46 MPa, an expansion ratio of 26.2%, and a back temperature of 253.5 °C after a 20-minute fire resistance test. This is mainly due to the increased introduction of melamine (gas source) in Example 7, which resulted in more gas being generated after the coating was ablated, thus increasing the expansion ratio of the system and improving its fire resistance.

[0138] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A water-based fire-retardant coating with an expanded carbon layer reinforcement, characterized in that, Based on a total mass fraction of 100% for the expanded carbon layer reinforced water-based fire retardant coating, the following raw materials are included in its preparation: Film-forming substance 18-30%, flame retardant 45-60%, modified titanium dioxide 3.5-12%, additives 1-5%, water 13-25%; The method for preparing the modified titanium dioxide includes the following steps: Titanium dioxide, a first dispersant, a boron compound, a silicon compound, and an amino compound are mixed, and the pH value is adjusted to 3-4 to perform the first modification, thereby obtaining boron / silicon modified titanium dioxide; the amino compound is γ-aminopropyltriethoxysilane. The boron / silicon modified titanium dioxide is mixed with a second dispersant and phytic acid solution to undergo a second modification, thereby obtaining modified titanium dioxide.

2. The expanded carbon layer reinforced water-based fire-retardant coating according to claim 1, characterized in that, The boron compound includes one or more of trimethoxyborooxy ester, boric acid, and trimethyl borate; The silicon compound includes one or more of tetramethyl orthosilicate, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, and tetramethyl orthosilicate; The mass ratio of the titanium dioxide, boron compound, silicon compound, and amino compound is 8~10:1.25~2.5:0.5~1.5:1~3; The first modification was performed at a temperature of 60-90 °C for 5-7 h.

3. The expanded carbon layer reinforced water-based fire-retardant coating according to claim 1, characterized in that, The mass ratio of the boron / silicon modified titanium dioxide to the phytic acid solution is 2.5~5:1; The phytic acid solution has a mass concentration of 70%. The second modification is performed at a temperature of 60-90 °C for 3-5 h.

4. The expanded carbon layer reinforced water-based fire-retardant coating according to claim 1, characterized in that, The film-forming substance includes at least one of waterborne epoxy resin, waterborne acrylic resin, waterborne polyurethane resin, waterborne silicone resin, and waterborne alkyd resin.

5. The expanded carbon layer reinforced water-based fire-retardant coating according to claim 4, characterized in that, When the film-forming substance is an aqueous epoxy resin, the film-forming substance also includes a curing agent; the mass ratio of the aqueous epoxy resin to the curing agent is 10~20:

1.

6. The expanded carbon layer reinforced water-based fire-retardant coating according to claim 1, characterized in that, The flame retardant includes ammonium polyphosphate, pentaerythritol, and melamine; the mass ratio of ammonium polyphosphate, pentaerythritol, and melamine is 2.67~3.25:1~1.5:1.25~1.

75.

7. The expanded carbon layer reinforced water-based fire-retardant coating according to claim 1, characterized in that, The additives include at least one of dispersants, thickeners, wetting agents, defoamers, and antibacterial agents.

8. The expanded carbon layer reinforced water-based fire-retardant coating according to claim 7, characterized in that, The dispersant includes sodium polyacrylate; the thickener includes a polyurethane thickener; the wetting agent includes a nonionic wetting agent; the defoamer includes an organosilicone defoamer; and the antibacterial agent includes Kathon antibacterial agent.

9. A method for preparing the expanded carbon layer reinforced waterborne fire-retardant coating according to any one of claims 1 to 8, characterized in that, Includes the following steps: The film-forming substance is dispersed in water, and flame retardants, modified titanium dioxide, and additives are added to obtain an expanded carbon layer reinforced waterborne fireproof coating.

10. The application of the expanded carbon layer reinforced waterborne fire retardant coating according to any one of claims 1 to 8 or the expanded carbon layer reinforced waterborne fire retardant coating prepared by the preparation method according to claim 9 in the fire retardant coating of steel structures.

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