Environment-friendly fireproof coating and preparation method thereof

Abstract

The application belongs to the technical field of fireproof paint and specifically relates to an environment-friendly fireproof paint and a preparation method thereof, wherein the environment-friendly fireproof paint comprises the following components in parts by mass: modified amphiphilic zinc borate composite material 5-20 parts, charring agent 5-10 parts, water-based polyurethane 50-80 parts, dispersing agent 1-3 parts, rheological modifier 0.5-2 parts, leveling agent 0.5-2 parts, modified filler 3-10 parts, deionized water 50-100 parts, pH regulator 0.1-0.5 parts, and the modified amphiphilic zinc borate composite material has a double-layer core-shell structure. The environment-friendly fireproof paint has excellent fireproof performance, low volatile organic compound release and good construction performance by introducing the modified amphiphilic zinc borate composite material and optimizing the formula composition.

Description

Technical Field

[0001] This invention belongs to the field of fire-retardant coating technology, specifically an environmentally friendly fire-retardant coating and its preparation method. Background Technology

[0002] In modern industrial and civil construction, fire-retardant coatings, as a crucial passive fire safety material, form a heat-insulating and flame-retardant protective layer on the substrate surface. During a fire, this effectively delays structural damage and inhibits the spread of fire, buying valuable time for evacuation and fire rescue. Their technological development and widespread application are of irreplaceable importance in protecting life and property. The technological development of fire-retardant coatings exhibits two core trends: firstly, the pursuit of more efficient and reliable flame-retardant performance; and secondly, a comprehensive transition to environmentally friendly water-based systems with low volatile organic compound (VOC) content and no toxicity. How to achieve both environmental friendliness of coating components and long-term service stability while ensuring excellent fire-retardant performance has become an important research direction.

[0003] Chinese patent CN103242721B discloses a fire-retardant coating based on polyvinyl acetate emulsion. It achieves a relatively effective fire-retardant effect by compounding trichloroethyl phosphate and boric acid as core flame-retardant components, and the preparation process is relatively simple. Chinese patent CN105038573B uses polyurethane acrylate and modified magnesium hydroxide as the main components. It replaces traditional halogenated flame retardants with halogen-free flame retardants such as magnesium hydroxide. Magnesium hydroxide decomposes upon heating, releasing water vapor, which has the dual functions of absorbing heat, cooling, and diluting flammable gases, significantly improving the environmental performance of the coating. Simultaneously, to enhance the synergistic flame-retardant effect, this scheme introduces borax as an auxiliary flame retardant, utilizing its characteristic of melting and forming a film at high temperatures to optimize fire-retardant performance.

[0004] However, both of these technical solutions utilize boric acid or borax, which have relatively weak chemical stability in aqueous systems, as key char-forming accelerators and glass phase forming agents. In acidic environments, boric acid has low solubility and is easily recrystallized from the system, while borax reacts chemically with acidic substances and may similarly transform into boric acid, which has even lower solubility. This precipitation or reaction of flame retardants triggers a series of negative effects. First, the precipitation and agglomeration of flame retardant particles disrupts their uniform dispersion in the coating system, leading to microscopic defects within the cured coating. This not only reduces the physical and mechanical properties of the coating and its adhesion to the substrate, but more seriously, it causes uneven distribution of the effective flame-retardant components. In the event of a fire, these areas lacking flame retardant become weak points in the fire protection system, unable to form a continuous, dense protective char layer, thus significantly weakening the overall fire-resistant performance. Furthermore, this chemical instability reduces the storage stability of the coating product, shortens its shelf life, and causes significant performance fluctuations between different batches and under different storage conditions, making it difficult to guarantee the uniformity of quality in engineering applications.

[0005] Therefore, developing a new type of fire-retardant coating that not only possesses excellent intrinsic flame retardancy and smoke suppression performance, but more importantly, can maintain high chemical stability and physical dispersion stability in complex chemical environments has become a technical challenge currently faced by those skilled in the art. Summary of the Invention

[0006] This invention provides an environmentally friendly fire-retardant coating with excellent fire resistance, low volatile organic compound (VOC) emission, and good application performance, making it suitable for modern construction, industry, and environmental protection fields.

[0007] To achieve the above objectives, the technical solution of the present invention is: an environmentally friendly fire-retardant coating, comprising the following components by weight: 5-20 parts of modified amphiphilic zinc borate composite material 5-10 parts of charring agent 50-80 parts of waterborne polyurethane 1-3 parts dispersant 0.5-2 parts of rheology modifier, Leveling agent 0.5-2 parts, 3-10 parts of modified filler 50-100 parts deionized water pH adjuster 0.1-0.5 parts, The modified amphiphilic zinc borate composite material has a double-layer core-shell structure: The core is composed of porous zinc borate particles; The outer shell is an amphiphilic composite coating layer, consisting of the following layers from the inside out: a) Hydrophobic silane layer; b) Hydrophilic polyether silane layer.

[0008] The modified amphiphilic zinc borate composite material disclosed in this invention has significant differences compared to traditional zinc borate flame retardants. Traditional zinc borate particles have relatively smooth surfaces and low surface areas, while the modified amphiphilic zinc borate composite material of this invention introduces a porous structure through template pore-forming technology, significantly increasing its specific surface area to 30-50 m². 2 / g. This porous structure enhances the material's adsorption capacity. Furthermore, the amphiphilic composite coating design further improves the material's overall performance. The presence of the hydrophobic silane layer endows the material with excellent waterproof properties, while the hydrophilic polyether silane layer improves the material's dispersibility in aqueous systems. The two-layer coating structure is formed through a stepwise chemical reaction, ensuring the interfacial bonding strength between the hydrophobic and hydrophilic layers and preventing peeling during use.

[0009] The environmentally friendly fire-retardant coating disclosed in this invention has significant differences from existing technologies. Existing fire-retardant coatings typically use flame retardants in a single form, lacking functional surface modification, and are prone to precipitation or reaction in acidic environments, leading to a decline in coating performance. In contrast, the modified amphiphilic zinc borate composite material mentioned in this invention, through a double-layer core-shell structure design, endows the flame retardant with excellent acid resistance and stability. The porous zinc borate particles in the core have abundant pores, and their molecules contain four parts water of crystallization. Therefore, during combustion, when heated, they rapidly release water of crystallization to absorb heat from the fire source. Simultaneously, the nanopores efficiently adsorb combustible gases, effectively absorbing heat and playing a flame-retardant role. Further during combustion, after zinc borate decomposes at high temperatures, it continues to exert a highly efficient flame-retardant effect through multiple mechanisms: its pyrolysis product, active boron oxide, forms a molten glass that flows and covers the surface of the char layer, forming a dense oxygen barrier that effectively blocks heat and mass transfer and seals cracks; simultaneously, the generated nano-zinc oxide particles are embedded in the char layer skeleton, significantly enhancing the mechanical strength and thermal stability of the char body and preventing high-temperature collapse. In the gas phase, the boron oxides released during decomposition efficiently quench free radicals in the combustion chain reaction, inhibiting flame propagation, while ZnO catalyzes the conversion of carbon monoxide into carbon dioxide, reducing toxic fumes. Furthermore, these residues synergistically interact with ammonium polyphosphate in the system; ZnO catalyzes the accelerated dehydration of polyphosphate into char, and at higher temperatures, boron oxide reacts with polyphosphate-derived products and metal salt decomposition products to form a phosphorus-boron-metal element network, which is then converted into a thermally stable borophosphate ceramic network through a high-temperature chemical reaction. This network, in conjunction with the ZnO-reinforced char layer, forms a composite barrier system of inorganic ceramic framework + graphitized char layer, effectively isolating heat and oxygen even at extreme temperatures, thus maintaining its flame-retardant function. The metal oxides generated from the decomposition of carbonate fillers can also be converted into a thermally stable borate ceramic body along with boron oxide, ultimately constructing a three-dimensional fireproof system of gas-phase free radical capture, molten glass sealing, and ceramicized char layer reinforcement, achieving full-cycle protection from the initial heat absorption and dehydration stage of a fire to the structural reinforcement stage at high temperatures. Its amphiphilic composite coating is achieved through a two-step coating process. The hydrophobic silane layer provides high contact angle hydrophobicity to prevent moisture penetration, while the hydrophilic polyether silane layer enhances the compatibility between the material and the coating matrix, avoiding uneven dispersion caused by poor interfacial compatibility. This dual-layer coating structure not only improves the water resistance and stability of the flame retardant but also significantly reduces the leaching of zinc ions and blocks acid attack on zinc borate, thereby extending the coating's service life.

[0010] The flame-retardant effect in this solution is not achieved by a single component. Besides the aforementioned ammonium polyphosphate decomposing upon heating to generate polyphosphate catalytic resin that dehydrates and chars, this process synergistically promotes the formation of a dense, expanded char layer with the phosphorus source in the organophosphorus modified leveling agent. This char layer physically isolates oxygen and heat transmission. Furthermore, the surface-modified inorganic carbonate filler decomposes upon heating, releasing gases that dilute oxygen. Its molten state covers the char layer surface, further strengthening the heat insulation barrier, forming a triple fire-retardant network of dehydration and cooling, gas-phase dilution, and char layer sealing. The entire system, through molecular design and interface regulation between components, achieves both high flame retardancy and environmental friendliness.

[0011] This invention further discloses the preparation process of the above-mentioned environmentally friendly fire-retardant coating, including the following steps: Step (1): Add the modified amphiphilic zinc borate composite material, charring agent, dispersant and modified filler to deionized water according to the ratio, and ultrasonically disperse for 10 minutes; Step (2): Add water-based polyurethane and stir at 300 rpm for 20 minutes; Step (3): Continue stirring and add rheology modifier and leveling agent; Step (4): Continue stirring and add pH adjuster to maintain the pH value of the system at 6.0-8.0, and adjust the viscosity to 5000-8000 mPa•s; Step (5): After filtering with a 100-mesh sieve, package to obtain an environmentally friendly fireproof coating.

[0012] Preferably, in step (1), the modified filler is prepared by: ultrasonically dispersing 5-10 parts of filler in 50-100 parts of anhydrous ethanol, adding 0.5-1 parts of polycarboxylate dispersant and 0.05-0.2 parts of silane coupling agent, stirring evenly, adding 3-5 parts of water, ball milling for 20-30 minutes, unloading, washing with deionized water until neutral, and drying to obtain the modified filler.

[0013] Preferably, in step (1), the filler is one or more of calcium carbonate, aluminum hydroxide, magnesium hydroxide, and magnesium carbonate, and the particle size of the filler is 1-5 μm. After surface modification, the surface energy of the filler is significantly reduced, and its compatibility with the waterborne polyurethane matrix is ​​improved, thereby reducing the agglomeration phenomenon in the coating system.

[0014] Preferably, in step (2), the solid content of the waterborne polyurethane is 30%-50%, and the glass transition temperature is -20℃ to 0℃. As a film-forming resin, waterborne polyurethane provides the basic physical properties of the coating, while its low VOC content meets environmental protection requirements.

[0015] Preferably, in step (3), the leveling agent is an organophosphorus modified organosilicon leveling agent. The addition of the leveling agent improves the surface tension of the coating, enabling it to spread quickly during the coating process and form a uniform coating.

[0016] Preferably, in step (4), the pH adjuster is triethanolamine, and the pH value of the adjusted system is 6.0-8.0. The control of pH value ensures the stability of the coating system and avoids precipitation or gelation caused by pH fluctuations.

[0017] Preferably, in step (1), the preparation method of the modified amphiphilic zinc borate composite material includes the following steps: Step (a) Template pore formation: 5-15 parts of SiO2 microspheres are ultrasonically dispersed in 10-75 parts of anhydrous ethanol, 10-20 parts of boric acid and 5-10 parts of zinc oxide are added, and the mixture is refluxed at 75-85℃ for 2-3 hours to generate SiO2 microspheres coated with zinc borate precursor. Then, the mixture is calcined at 550-650℃ for 2-3 hours, and the SiO2 template is removed by immersion in NaOH solution to obtain porous zinc borate particles. Step (b) Hydrophobic coating: 10-15 parts of porous zinc borate are ultrasonically dispersed in 50-75 parts of toluene, and 0.1-0.15 parts of heptadecafluorodecyltrimethoxysilane are added. The mixture is refluxed at 75-85°C for 2-3 hours to obtain hydrophobic particles. Step (c) Hydrophilic layer coating: Transfer 10-15 parts of hydrophobic particles to 50-75 parts of ethanol / water mixed solvent (volume ratio 8:2), add 0.4-0.6 parts of polyether silane, stir at 55-65℃ for 2.5-3.5 hours, wash with ethanol, dry at 50-60℃, and obtain the modified amphiphilic zinc borate composite material after dispersion.

[0018] Preferably, in step (a), the SiO2 microspheres have a particle size of 50-100 nm. The SiO2 microspheres serve as a template, and their particle size determines the pore size distribution of the final porous zinc borate particles.

[0019] Preferably, in step (a), the concentration of the NaOH solution is 10%-15% by mass, the temperature for removing the SiO2 template is 60°C, the time is 2 hours, and the removal rate is >99%. The selectivity of the NaOH solution and the reaction conditions ensure the complete removal of the SiO2 template while avoiding damage to the porous zinc borate particles.

[0020] The porous zinc borate particles in the core have an abundant pore structure, and they acquired water of crystallization during rinsing with NaOH solution. Preferably, in step (3), the rheology modifier is a hydrophobically modified ethylene oxide polyurethane. The addition of the rheology modifier improves the thixotropy of the coating, making it stable during storage and able to quickly restore its fluidity during application.

[0021] This invention's environmentally friendly fire-retardant coating addresses the problem of traditional flame retardants easily precipitating or reacting in acidic environments through the design of a modified amphiphilic zinc borate composite material. The introduction of a double-layer core-shell structure endows the flame retardant with excellent water resistance and stability, while reducing the leaching of zinc ions. Furthermore, the abundant pores of the porous zinc borate particles enable rapid release of active substances at high temperatures, promoting the decomposition of the charring agent to form a dense char layer, thereby significantly improving the coating's flame-retardant performance. The entire preparation process is simple, and the raw materials are widely available, making it suitable for large-scale production and providing technical support for the widespread application of environmentally friendly fire-retardant coatings.

[0022] The working principle and beneficial effects of this invention are as follows: 1. This invention significantly improves the flame retardant and environmental performance of coatings by introducing a modified amphiphilic zinc borate composite material. The high specific surface area of ​​the porous zinc borate particles and the design of the amphiphilic composite coating layer enable the coating to rapidly form a dense char layer during combustion, effectively isolating heat and oxygen while reducing the release of harmful gases.

[0023] 2. This invention uses waterborne polyurethane as the film-forming resin, which reduces the VOC content of the coating and meets modern environmental protection requirements. The preparation process is simple, and the components can be uniformly mixed by conventional stirring and ultrasonic dispersion, making it suitable for large-scale production. By modifying the surface of the filler and selecting the leveling agent, the construction performance and coating quality of the coating are further improved, meeting the needs of different application scenarios. Detailed Implementation

[0024] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0025] In the following examples and comparative examples, the ammonium polyphosphate was HT-208, purchased from Henan Mingzhixin Chemical Products Co., Ltd.; the polycarboxylate dispersant was dispersant 5040; the solid content of the waterborne polyurethane was 40%; the hydrophobically modified ethylene oxide polyurethane was Yale Shun™ RM-12W; the organophosphorus modified organosilicon leveling agent was BYK-378; the silane coupling agent was KH-550; and the polyether silane was DMSC-212, purchased from Sichuan Qiaoshui Technology Co., Ltd.

[0026] General Implementation Examples A method for preparing an environmentally friendly fire-retardant coating includes the following steps: Step (1) Add 5-20 parts of modified amphiphilic zinc borate composite material, 5-10 parts of char-forming agent ammonium polyphosphate, 1-3 parts of polycarboxylate dispersant, and 3-10 parts of modified filler to 50-100 parts of deionized water according to the ratio, and ultrasonically disperse for 10 minutes; Step (2) Add 50-80 parts of waterborne polyurethane and stir at 300 rpm for 20 minutes; Step (3) Continue stirring and add 0.5-2 parts of hydrophobic modified ethylene oxide polyurethane rheology modifier and 0.5-2 parts of organophosphorus modified organosilicon leveling agent BYK-378; Step (4) Continue stirring and add 0.1-0.5 parts of the pH adjuster triethanolamine to make the pH of the system 6.0-8.0 and adjust the viscosity to 5000-8000 mPa•s; Step (5) Filter and package the product using a 100-mesh sieve to obtain an environmentally friendly fire-retardant coating; The modified filler is prepared as follows: 5-10 parts of filler are ultrasonically dispersed in 50-100 parts of anhydrous ethanol, 0.5-1 parts of polycarboxylate dispersant and 0.05-0.2 parts of silane coupling agent are added, stirred evenly, and then 3-5 parts of water are added. The mixture is ball-milled for 20-30 minutes, discharged, washed with deionized water until neutral, and dried to obtain the modified filler. The filler is one or more of calcium carbonate, aluminum hydroxide, magnesium hydroxide, and magnesium carbonate with a particle size of 1-5 μm. The modified amphiphilic zinc borate composite material was prepared by the following steps: Step (a) Template pore formation: 5-15 parts of SiO2 microspheres with a particle size of 50-100 nm are ultrasonically dispersed in 10-75 parts of anhydrous ethanol, 10-20 parts of boric acid and 5-10 parts of zinc oxide are added, and the mixture is refluxed at 75-85℃ for 2-3 hours to generate SiO2 microspheres coated with zinc borate precursor. Then, the mixture is calcined at 550-650℃ for 2-3 hours, immersed in 10%-15% NaOH solution, and soaked at 60℃ for 2 hours to remove SiO2 and obtain porous zinc borate particles. Step (b) Hydrophobic coating: 10-15 parts of porous zinc borate are ultrasonically dispersed in 50-75 parts of toluene, and 0.1-0.15 parts of heptadecafluorodecyltrimethoxysilane are added. The mixture is refluxed at 75-85°C for 2-3 hours to obtain hydrophobic particles. Step (c) Hydrophilic layer coating: Transfer 10-15 parts of hydrophobic particles to 50-75 parts of ethanol / water mixed solvent (volume ratio 8:2), add 0.4-0.6 parts of polyether silane, stir at 55-65℃ for 2.5-3.5 hours, wash with ethanol, dry at 50-60℃, disperse, and obtain modified amphiphilic zinc borate composite material.

[0027] Example 1 A method for preparing an environmentally friendly fire-retardant coating includes the following steps: Step (1) Add 5 parts of modified amphiphilic zinc borate composite material, 5 parts of char-forming agent ammonium polyphosphate, 1 part of polycarboxylate dispersant, and 3 parts of modified filler to 50 parts of deionized water according to the ratio, and ultrasonically disperse for 10 minutes. Step (2) Add 50 parts of water-based polyurethane and stir at 300 rpm for 20 minutes; Step (3) Continue stirring and add 0.5 parts of hydrophobic modified ethylene oxide polyurethane rheology modifier and 0.5 parts of organophosphorus modified organosilicon leveling agent BYK-378; Step (4) Continue stirring and add 0.1 parts of the pH adjuster triethanolamine to make the pH of the system 6.0 and adjust the viscosity to 5000 mPa•s; Step (5) Filter and package the product using a 100-mesh sieve to obtain an environmentally friendly fire-retardant coating; The modified filler was prepared by ultrasonically dispersing 5 parts of filler in 50 parts of anhydrous ethanol, adding 0.5 parts of polycarboxylate dispersant and 0.05 parts of silane coupling agent, stirring evenly, adding 3 parts of water, ball milling for 20 minutes, unloading, washing with deionized water until neutral, and drying to obtain surface-modified inorganic flame-retardant filler; the filler was 1μm calcium carbonate. The modified amphiphilic zinc borate composite material was prepared by the following steps: Step (a) Template pore formation: 5 parts of SiO2 microspheres with a particle size of 50 nm were ultrasonically dispersed in 10 parts of anhydrous ethanol, 10 parts of boric acid and 5 parts of zinc oxide were added, and the mixture was refluxed at 75°C for 2 hours to generate SiO2 microspheres coated with zinc borate precursor. Then, the mixture was calcined at 550°C for 2 hours, immersed in 10% NaOH solution, and soaked at 60°C for 2 hours to remove SiO2 and obtain porous zinc borate particles. Step (b) Hydrophobic coating: 10 parts of porous zinc borate were ultrasonically dispersed in 50 parts of toluene, and 0.1 parts of heptadecafluorodecyltrimethoxysilane were added. The mixture was refluxed at 75°C for 2 hours to obtain hydrophobic particles. Step (c) Hydrophilic layer coating: 10 parts of hydrophobic particles were transferred to 50 parts of ethanol / water mixed solvent (volume ratio 8:2), 0.4 parts of polyether silane were added, stirred at 55°C for 2.5 hours, washed with ethanol, dried at 50°C, and dispersed to obtain the modified amphiphilic zinc borate composite material.

[0028] Example 2 A method for preparing an environmentally friendly fire-retardant coating includes the following steps: Step (1) Add 12 parts of modified amphiphilic zinc borate composite material, 8 parts of char-forming agent ammonium polyphosphate, 2 parts of polycarboxylate dispersant, and 6 parts of modified filler to 75 parts of deionized water according to the ratio, and ultrasonically disperse for 10 minutes. Step (2) Add 65 parts of water-based polyurethane and stir at 300 rpm for 20 minutes; Step (3) Continue stirring and add 1.2 parts of hydrophobic modified ethylene oxide polyurethane rheology modifier and 1.2 parts of organophosphorus modified organosilicon leveling agent BYK-378; Step (4) Continue stirring and add 0.3 parts of the pH adjuster triethanolamine to make the pH of the system 7.0 and adjust the viscosity to 6500 mPa•s; Step (5) Filter and package the product using a 100-mesh sieve to obtain an environmentally friendly fire-retardant coating; The modified filler was prepared by ultrasonically dispersing 7 parts of filler in 75 parts of anhydrous ethanol, adding 0.7 parts of polycarboxylate dispersant and 0.12 parts of silane coupling agent, stirring evenly, adding 4 parts of water, ball milling for 25 minutes, unloading, washing with deionized water until neutral, and drying to obtain surface-modified inorganic flame-retardant filler; the filler was a mixture of 3μm calcium carbonate and aluminum hydroxide. The modified amphiphilic zinc borate composite material was prepared by the following steps: Step (a) Template pore formation: 10 parts of SiO2 microspheres with a particle size of 80 nm were ultrasonically dispersed in 45 parts of anhydrous ethanol, 15 parts of boric acid and 8 parts of zinc oxide were added, and the mixture was refluxed at 80°C for 2.5 hours to generate SiO2 microspheres coated with zinc borate precursor. Then, the mixture was calcined at 600°C for 2.5 hours, immersed in 12% NaOH solution, and soaked at 60°C for 2 hours to remove SiO2 and obtain porous zinc borate particles. Step (b) Hydrophobic coating: 12 parts of porous zinc borate were ultrasonically dispersed in 60 parts of toluene, and 0.12 parts of heptadecafluorodecyltrimethoxysilane were added. The mixture was refluxed at 80°C for 2.5 hours to obtain hydrophobic particles. Step (c) Hydrophilic layer coating: 12 parts of hydrophobic particles were transferred to 60 parts of ethanol / water mixed solvent (volume ratio 8:2), 0.5 parts of polyether silane were added, stirred at 60°C for 3 hours, washed with ethanol, dried at 55°C, and dispersed to obtain the modified amphiphilic zinc borate composite material.

[0029] Example 3 A method for preparing an environmentally friendly fire-retardant coating includes the following steps: Step (1) Add 20 parts of modified amphiphilic zinc borate composite material, 10 parts of char-forming agent ammonium polyphosphate, 3 parts of polycarboxylate dispersant, and 10 parts of modified filler to 100 parts of deionized water according to the ratio, and ultrasonically disperse for 10 minutes. Step (2) Add 80 parts of waterborne polyurethane and stir at 300 rpm for 20 minutes; Step (3) Continue stirring and add 2 parts of hydrophobic modified ethylene oxide polyurethane rheology modifier and 2 parts of organophosphorus modified organosilicon leveling agent BYK-378; Step (4) Continue stirring and add 0.5 parts of the pH adjuster triethanolamine to make the pH of the system 8.0 and adjust the viscosity to 8000 mPa•s; Step (5) Filter and package the product using a 100-mesh sieve to obtain an environmentally friendly fire-retardant coating; The modified filler was prepared by ultrasonically dispersing 10 parts of filler in 100 parts of anhydrous ethanol, adding 1 part of polycarboxylate dispersant and 0.2 parts of silane coupling agent, stirring evenly, adding 5 parts of water, ball milling for 30 minutes, unloading, washing with deionized water until neutral, and drying to obtain surface-modified inorganic flame-retardant filler; the filler was a 5μm mixture of magnesium hydroxide and magnesium carbonate. The modified amphiphilic zinc borate composite material was prepared by the following steps: Step (a) Template pore formation: 15 parts of SiO2 microspheres with a particle size of 100 nm were ultrasonically dispersed in 75 parts of anhydrous ethanol, 20 parts of boric acid and 10 parts of zinc oxide were added, and the mixture was refluxed at 85°C for 3 hours to generate SiO2 microspheres coated with zinc borate precursor. Then, the mixture was calcined at 650°C for 3 hours, immersed in 15% NaOH solution, and soaked at 60°C for 2 hours to remove SiO2 and obtain porous zinc borate particles. Step (b) Hydrophobic coating: 15 parts of porous zinc borate were ultrasonically dispersed in 75 parts of toluene, and 0.15 parts of heptadecafluorodecyltrimethoxysilane were added. The mixture was refluxed at 85°C for 3 hours to obtain hydrophobic particles. Step (c) Hydrophilic layer coating: 15 parts of hydrophobic particles were transferred to 75 parts of ethanol / water mixed solvent (volume ratio 8:2), 0.6 parts of polyether silane were added, stirred at 65°C for 3.5 hours, washed with ethanol, dried at 60°C, and dispersed to obtain the modified amphiphilic zinc borate composite material.

[0030] Comparative Example 1 The difference from Example 1 is that only zinc borate is added: A method for preparing an environmentally friendly fire-retardant coating includes the following steps: Step (1) Add 5 parts of zinc borate, 5 parts of char-forming agent ammonium polyphosphate, 1 part of polycarboxylate dispersant, and 3 parts of modified filler to 50 parts of deionized water according to the ratio, and ultrasonically disperse for 10 minutes. Step (2) Add 50 parts of water-based polyurethane and stir at 300 rpm for 20 minutes; Step (3) Continue stirring and add 0.5 parts of hydrophobic modified ethylene oxide polyurethane rheology modifier and 0.5 parts of organophosphorus modified organosilicon leveling agent BYK-378; Step (4) Continue stirring and add 0.1 parts of the pH adjuster triethanolamine to make the pH of the system 6.0 and adjust the viscosity to 5000 mPa•s; Step (5) Filter and package the product using a 100-mesh sieve to obtain an environmentally friendly fire-retardant coating; The modified filler was prepared by ultrasonically dispersing 5 parts of filler in 50 parts of anhydrous ethanol, adding 0.5 parts of polycarboxylate dispersant and 0.05 parts of silane coupling agent, stirring evenly, adding 3 parts of water, ball milling for 20 minutes, unloading, washing with deionized water until neutral, and drying to obtain surface-modified inorganic flame-retardant filler; the filler was 1μm calcium carbonate.

[0031] Comparative Example 2 The difference from Example 1 is that zinc borate only undergoes hydrophobic modification: A method for preparing an environmentally friendly fire-retardant coating includes the following steps: Step (1) Add 5 parts of hydrophobic modified zinc borate, 5 parts of char-forming agent ammonium polyphosphate, 1 part of polycarboxylate dispersant, and 3 parts of modified filler to 50 parts of deionized water according to the ratio, and ultrasonically disperse for 10 minutes. Step (2) Add 50 parts of water-based polyurethane and stir at 300 rpm for 20 minutes; Step (3) Continue stirring and add 0.5 parts of hydrophobic modified ethylene oxide polyurethane rheology modifier and 0.5 parts of organophosphorus modified organosilicon leveling agent BYK-378; Step (4) Continue stirring and add 0.1 parts of the pH adjuster triethanolamine to make the pH of the system 6.0 and adjust the viscosity to 5000 mPa•s; Step (5) Filter and package the product using a 100-mesh sieve to obtain an environmentally friendly fire-retardant coating; The modified filler was prepared by ultrasonically dispersing 5 parts of filler in 50 parts of anhydrous ethanol, adding 0.5 parts of polycarboxylate dispersant and 0.05 parts of silane coupling agent, stirring evenly, adding 3 parts of water, ball milling for 20 minutes, unloading, washing with deionized water until neutral, and drying to obtain surface-modified inorganic flame-retardant filler; the filler was 1μm calcium carbonate. Hydrophobically modified zinc borate is prepared by the following steps: Step (a) Template pore formation: 5 parts of SiO2 microspheres with a particle size of 50 nm were ultrasonically dispersed in 10 parts of anhydrous ethanol, 10 parts of boric acid and 5 parts of zinc oxide were added, and the mixture was refluxed at 75°C for 2 hours to generate SiO2 microspheres coated with zinc borate precursor. Then, the mixture was calcined at 550°C for 2 hours, immersed in 10% NaOH solution, and soaked at 60°C for 2 hours to remove SiO2 and obtain porous zinc borate particles. Step (b) Hydrophobic coating: 10 parts of porous zinc borate were ultrasonically dispersed in 50 parts of toluene, and 0.1 parts of heptadecafluorodecyltrimethoxysilane were added. The mixture was refluxed at 75°C for 2 hours, washed, and dried to obtain hydrophobically modified zinc borate.

[0032] Comparative Example 3 The difference from Example 1 is that zinc borate was not modified to be hydrophobic: A method for preparing an environmentally friendly fire-retardant coating includes the following steps: Step (1) Add 5 parts of modified zinc borate, 5 parts of char-forming agent ammonium polyphosphate, 1 part of polycarboxylate dispersant, and 3 parts of modified filler to 50 parts of deionized water according to the ratio, and ultrasonically disperse for 10 minutes. Step (2) Add 50 parts of water-based polyurethane and stir at 300 rpm for 20 minutes; Step (3) Continue stirring and add 0.5 parts of hydrophobic modified ethylene oxide polyurethane rheology modifier and 0.5 parts of organophosphorus modified organosilicon leveling agent BYK-378; Step (4) Continue stirring and add 0.1 parts of the pH adjuster triethanolamine to make the pH of the system 6.0 and adjust the viscosity to 5000 mPa•s; Step (5) Filter and package the product using a 100-mesh sieve to obtain an environmentally friendly fire-retardant coating; The modified filler was prepared by ultrasonically dispersing 5 parts of filler in 50 parts of anhydrous ethanol, adding 0.5 parts of polycarboxylate dispersant and 0.05 parts of silane coupling agent, stirring evenly, adding 3 parts of water, ball milling for 20 minutes, unloading, washing with deionized water until neutral, and drying to obtain surface-modified inorganic flame-retardant filler; the filler was 1μm calcium carbonate. Modified zinc borate is prepared by the following steps: Step (a) Template pore formation: 5 parts of SiO2 microspheres with a particle size of 50 nm were ultrasonically dispersed in 10 parts of anhydrous ethanol, 10 parts of boric acid and 5 parts of zinc oxide were added, and the mixture was refluxed at 75°C for 2 hours to generate SiO2 microspheres coated with zinc borate precursor. Then, the mixture was calcined at 550°C for 2 hours, immersed in 10% NaOH solution, and soaked at 60°C for 2 hours to remove SiO2 and obtain porous zinc borate particles. Step (b) Hydrophilic coating: 10 parts of porous zinc borate particles were transferred to 50 parts of ethanol / water mixed solvent (volume ratio 8:2), 0.4 parts of polyether silane were added, stirred at 55°C for 2.5 hours, washed with ethanol, dried at 50°C, and dispersed to obtain modified zinc borate.

[0033] Comparative Example 4 The difference from Example 1 is that the filler was not modified: A method for preparing an environmentally friendly fire-retardant coating includes the following steps: Step (1) Add 5 parts of modified amphiphilic zinc borate composite material, 5 parts of char-forming agent ammonium polyphosphate, 1 part of polycarboxylate dispersant, and 3 parts of calcium carbonate with a particle size of 1 μm to 50 parts of deionized water according to the ratio, and ultrasonically disperse for 10 minutes. Step (2) Add 50 parts of water-based polyurethane and stir at 300 rpm for 20 minutes; Step (3) Continue stirring and add 0.5 parts of hydrophobic modified ethylene oxide polyurethane rheology modifier and 0.5 parts of organophosphorus modified organosilicon leveling agent BYK-378; Step (4) Continue stirring and add 0.1 parts of the pH adjuster triethanolamine to make the pH of the system 6.0 and adjust the viscosity to 5000 mPa•s; Step (5) Filter and package the product using a 100-mesh sieve to obtain an environmentally friendly fire-retardant coating; The modified amphiphilic zinc borate composite material was prepared by the following steps: Step (a) Template pore formation: 5 parts of SiO2 microspheres with a particle size of 50 nm were ultrasonically dispersed in 10 parts of anhydrous ethanol, 10 parts of boric acid and 5 parts of zinc oxide were added, and the mixture was refluxed at 75°C for 2 hours to generate SiO2 microspheres coated with zinc borate precursor. Then, the mixture was calcined at 550°C for 2 hours, immersed in 10% NaOH solution, and soaked at 60°C for 2 hours to remove SiO2 and obtain porous zinc borate particles. Step (b) Hydrophobic coating: 10 parts of porous zinc borate were ultrasonically dispersed in 50 parts of toluene, and 0.1 parts of heptadecafluorodecyltrimethoxysilane were added. The mixture was refluxed at 75°C for 2 hours to obtain hydrophobic particles. Step (c) Hydrophilic layer coating: 10 parts of hydrophobic particles were transferred to 50 parts of ethanol / water mixed solvent (volume ratio 8:2), 0.4 parts of polyether silane were added, stirred at 55°C for 2.5 hours, washed with ethanol, dried at 50°C, and dispersed to obtain the modified amphiphilic zinc borate composite material.

[0034] Comparative Example 5 The difference from Example 1 is that the charring agent and leveling agent are phosphorus-free components: A method for preparing an environmentally friendly fire-retardant coating includes the following steps: Step (1) Add 5 parts of modified amphiphilic zinc borate composite material, 5 parts of carbonizing agent polyvinyl alcohol, 1 part of polycarboxylate dispersant, and 3 parts of modified filler to 50 parts of deionized water according to the ratio, and ultrasonically disperse for 10 minutes. Step (2) Add 50 parts of water-based polyurethane and stir at 300 rpm for 20 minutes; Step (3) Continue stirring and add 0.5 parts of rheology modifier hydroxypropyl methylcellulose and 0.5 parts of silicone leveling agent BYK-333; Step (4) Continue stirring and add 0.1 parts of the pH adjuster triethanolamine to make the pH of the system 6.0 and adjust the viscosity to 5000 mPa•s; Step (5) Filter and package the product using a 100-mesh sieve to obtain an environmentally friendly fire-retardant coating; The modified filler was prepared by ultrasonically dispersing 5 parts of filler in 50 parts of anhydrous ethanol, adding 0.5 parts of polycarboxylate dispersant and 0.05 parts of silane coupling agent, stirring evenly, adding 3 parts of water, ball milling for 20 minutes, unloading, washing with deionized water until neutral, and drying to obtain surface-modified inorganic flame-retardant filler; the filler was 1μm calcium carbonate. The modified amphiphilic zinc borate composite material was prepared by the following steps: Step (a) Template pore formation: 5 parts of SiO2 microspheres with a particle size of 50 nm were ultrasonically dispersed in 10 parts of anhydrous ethanol, 10 parts of boric acid and 5 parts of zinc oxide were added, and the mixture was refluxed at 75°C for 2 hours to generate SiO2 microspheres coated with zinc borate precursor. Then, the mixture was calcined at 550°C for 2 hours, immersed in 10% NaOH solution, and soaked at 60°C for 2 hours to remove SiO2 and obtain porous zinc borate particles. Step (b) Hydrophobic coating: 10 parts of porous zinc borate were ultrasonically dispersed in 50 parts of toluene, and 0.1 parts of heptadecafluorodecyltrimethoxysilane were added. The mixture was refluxed at 75°C for 2 hours to obtain hydrophobic particles. Step (c) Hydrophilic layer coating: 10 parts of hydrophobic particles were transferred to 50 parts of ethanol / water mixed solvent (volume ratio 8:2), 0.4 parts of polyether silane were added, stirred at 55°C for 2.5 hours, washed with ethanol, dried at 50°C, and dispersed to obtain the modified amphiphilic zinc borate composite material.

[0035] Comparative Example 6 The difference from Example 1 is that no zinc borate-related components were added: A method for preparing an environmentally friendly fire-retardant coating includes the following steps: Step (1) Add 5 parts of ammonium polyphosphate char-forming agent, 1 part of polycarboxylate dispersant, and 3 parts of modified filler to 50 parts of deionized water according to the ratio, and ultrasonically disperse for 10 minutes; Step (2) Add 50 parts of water-based polyurethane and stir at 300 rpm for 20 minutes; Step (3) Continue stirring and add 0.5 parts of hydrophobic modified ethylene oxide polyurethane rheology modifier and 0.5 parts of organophosphorus modified organosilicon leveling agent BYK-378; Step (4) Continue stirring and add 0.1 parts of the pH adjuster triethanolamine to make the pH of the system 6.0 and adjust the viscosity to 5000 mPa•s; Step (5) Filter and package the product using a 100-mesh sieve to obtain an environmentally friendly fire-retardant coating; The modified filler was prepared by ultrasonically dispersing 5 parts of filler in 50 parts of anhydrous ethanol, adding 0.5 parts of polycarboxylate dispersant and 0.05 parts of silane coupling agent, stirring evenly, adding 3 parts of water, ball milling for 20 minutes, unloading, washing with deionized water until neutral, and drying to obtain surface-modified inorganic flame-retardant filler; the filler was 1μm calcium carbonate.

[0036] Comparative Example 7 The difference from Example 1 is that, after calcination in step (a), the sample was not immersed in NaOH solution: A method for preparing an environmentally friendly fire-retardant coating includes the following steps: Step (1) Add 5 parts of modified amphiphilic zinc borate / silica particle composite material, 5 parts of char-forming agent ammonium polyphosphate, 1 part of polycarboxylate dispersant, and 3 parts of modified filler to 50 parts of deionized water according to the ratio, and ultrasonically disperse for 10 minutes. Step (2) Add 50 parts of water-based polyurethane and stir at 300 rpm for 20 minutes; Step (3) Continue stirring and add 0.5 parts of hydrophobic modified ethylene oxide polyurethane rheology modifier and 0.5 parts of organophosphorus modified organosilicon leveling agent BYK-378; Step (4) Continue stirring and add 0.1 parts of the pH adjuster triethanolamine to make the pH of the system 6.0 and adjust the viscosity to 5000 mPa•s; Step (5) Filter and package the product using a 100-mesh sieve to obtain an environmentally friendly fire-retardant coating; The modified filler was prepared by ultrasonically dispersing 5 parts of filler in 50 parts of anhydrous ethanol, adding 0.5 parts of polycarboxylate dispersant and 0.05 parts of silane coupling agent, stirring evenly, adding 3 parts of water, ball milling for 20 minutes, unloading, washing with deionized water until neutral, and drying to obtain surface-modified inorganic flame-retardant filler; the filler was 1μm calcium carbonate. The modified amphiphilic zinc borate composite material was prepared by the following steps: Step (a) Template pore formation: 5 parts of SiO2 microspheres with a particle size of 50nm were ultrasonically dispersed in 10 parts of anhydrous ethanol, 10 parts of boric acid and 5 parts of zinc oxide were added, and the mixture was refluxed at 75℃ for 2 hours to generate SiO2 microspheres coated with zinc borate precursor. Then, the mixture was calcined at 550℃ for 2 hours to obtain zinc borate / silicon dioxide particles. Step (b) Hydrophobic coating: 10 parts of zinc borate / silica particles were ultrasonically dispersed in 50 parts of toluene, and 0.1 parts of heptadecafluorodecyltrimethoxysilane were added. The mixture was refluxed at 75°C for 2 hours to obtain hydrophobic particles. Step (c) Hydrophilic layer coating: 10 parts of hydrophobic particles were transferred to 50 parts of ethanol / water mixed solvent (volume ratio 8:2), 0.4 parts of polyether silane were added, stirred at 55°C for 2.5 hours, washed with ethanol, dried at 50°C, and dispersed to obtain the modified amphiphilic zinc borate / silica particle composite material.

[0037] Comparative Example 8 The difference from Example 1 is that the proportions of some components exceed the limits: A method for preparing an environmentally friendly fire-retardant coating includes the following steps: Step (1) Add 30 parts of modified amphiphilic zinc borate composite material, 3 parts of char-forming agent ammonium polyphosphate, 1 part of polycarboxylate dispersant, and 10 parts of modified filler to 50 parts of deionized water according to the ratio, and ultrasonically disperse for 10 minutes. Step (2) Add 90 parts of water-based polyurethane and stir at 300 rpm for 20 minutes; Step (3) Continue stirring and add 0.5 parts of hydrophobic modified ethylene oxide polyurethane rheology modifier and 0.5 parts of organophosphorus modified organosilicon leveling agent BYK-378; Step (4) Continue stirring and add 0.1 parts of the pH adjuster triethanolamine to make the pH of the system 6.0 and adjust the viscosity to 5000 mPa•s; Step (5) Filter and package the product using a 100-mesh sieve to obtain an environmentally friendly fire-retardant coating; The modified filler was prepared by ultrasonically dispersing 5 parts of filler in 50 parts of anhydrous ethanol, adding 0.5 parts of polycarboxylate dispersant and 0.05 parts of silane coupling agent, stirring evenly, adding 3 parts of water, ball milling for 20 minutes, unloading, washing with deionized water until neutral, and drying to obtain surface-modified inorganic flame-retardant filler; the filler was 1μm calcium carbonate. The modified amphiphilic zinc borate composite material was prepared by the following steps: Step (a) Template pore formation: 5 parts of SiO2 microspheres with a particle size of 50 nm were ultrasonically dispersed in 10 parts of anhydrous ethanol, 10 parts of boric acid and 5 parts of zinc oxide were added, and the mixture was refluxed at 75°C for 2 hours to generate SiO2 microspheres coated with zinc borate precursor. Then, the mixture was calcined at 550°C for 2 hours, immersed in 10% NaOH solution, and soaked at 60°C for 2 hours to remove SiO2 and obtain porous zinc borate particles. Step (b) Hydrophobic coating: 10 parts of porous zinc borate were ultrasonically dispersed in 50 parts of toluene, and 0.1 parts of heptadecafluorodecyltrimethoxysilane were added. The mixture was refluxed at 75°C for 2 hours to obtain hydrophobic particles. Step (c) Hydrophilic layer coating: 10 parts of hydrophobic particles were transferred to 50 parts of ethanol / water mixed solvent (volume ratio 8:2), 0.4 parts of polyether silane were added, stirred at 55°C for 2.5 hours, washed with ethanol, dried at 50°C, and dispersed to obtain the modified amphiphilic zinc borate composite material.

[0038] Comparative Example 9 The difference from Example 1 is that some components are in excessive or missing proportions: A method for preparing an environmentally friendly fire-retardant coating includes the following steps: Step (1) Add 3 parts of modified amphiphilic zinc borate composite material, 3 parts of char-forming agent ammonium polyphosphate, and 1 part of polycarboxylate dispersant to 50 parts of deionized water according to the ratio, and ultrasonically disperse for 10 minutes. Step (2) Add 90 parts of water-based polyurethane and stir at 300 rpm for 20 minutes; Step (3) Continue stirring and add 0.5 parts of hydrophobic modified ethylene oxide polyurethane rheology modifier; Step (4) Continue stirring and add 0.1 parts of the pH adjuster triethanolamine to make the pH of the system 6.0 and adjust the viscosity to 5000 mPa•s; Step (5) Filter and package the product using a 100-mesh sieve to obtain an environmentally friendly fire-retardant coating; The modified amphiphilic zinc borate composite material was prepared by the following steps: Step (a) Template pore formation: 5 parts of SiO2 microspheres with a particle size of 50 nm were ultrasonically dispersed in 10 parts of anhydrous ethanol, 10 parts of boric acid and 5 parts of zinc oxide were added, and the mixture was refluxed at 75°C for 2 hours to generate SiO2 microspheres coated with zinc borate precursor. Then, the mixture was calcined at 550°C for 2 hours, immersed in 10% NaOH solution, and soaked at 60°C for 2 hours to remove SiO2 and obtain porous zinc borate particles. Step (b) Hydrophobic coating: 10 parts of porous zinc borate were ultrasonically dispersed in 50 parts of toluene, and 0.1 parts of heptadecafluorodecyltrimethoxysilane were added. The mixture was refluxed at 75°C for 2 hours to obtain hydrophobic particles. Step (c) Hydrophilic layer coating: 10 parts of hydrophobic particles were transferred to 50 parts of ethanol / water mixed solvent (volume ratio 8:2), 0.4 parts of polyether silane were added, stirred at 55°C for 2.5 hours, washed with ethanol, dried at 50°C, and dispersed to obtain the modified amphiphilic zinc borate composite material.

[0039] Performance testing Storage stability test: The three coating samples were placed in a constant temperature oven at 50℃ for accelerated aging for 6 months. The changes in appearance were observed and the viscosity change rate was measured.

[0040] Flame retardant leaching test: Cured coatings (5cm×5cm×1mm) made from three different paints were immersed in 100mL of deionized water and placed in a constant temperature water bath at 40℃ for 7 days. The immersion solutions were then collected, and the zinc ion concentration in the water samples was detected using inductively coupled plasma mass spectrometry (ICP-MS).

[0041] Coating physical performance testing: A 1mm thick dry film coating was prepared on a steel plate according to national standards and tested after 7 days of curing. Adhesion testing adopted GB / T 9286-1998 (cross-cut test); acid and water resistance testing: The coated sample was immersed in acetic acid water with pH 3.5 for 24 hours and then tested again using the cross-cut test.

[0042] Fire resistance performance testing: A cone calorimeter was used to test the combustion behavior of the coating under a heat radiation flux of 50 kW / m², according to ISO 5660-1 standard. The ignition time (TTI), peak heat release rate (pHRR), total heat release (THR), and char residue after combustion were recorded.

[0043] Environmental testing: Refer to GB 24408-2020 for the control and testing of harmful substances in the coating itself; refer to GB / T 8323.2, GB / T 20285, and ISO 5660 for the testing of combustion smoke toxicity.

[0044] The test results are shown in Table 1.

[0045] Table 1. Performance test results of the examples and comparative examples.

[0046] The embodiment achieves performance improvement through the synergistic design of components and processes: In terms of components, the porous structure of the modified amphiphilic zinc borate composite material and the amphiphilic coating layer work synergistically to improve the dispersion stability of the flame retardant in the coating, and inhibit the dissolution of zinc ions in acidic environments through the hydrophobic layer. At the same time, the porous core adsorbs combustible gases and releases water of crystallization for endothermic effect, forming a dual mechanism of dehydration and charring-gas phase flame retardancy with the charring agent; waterborne polyurethane, as a low-VOC environmentally friendly resin, achieves good compatibility with surface-modified inorganic fillers by reducing surface energy, thus reducing filler agglomeration; phosphorus-containing leveling agents and rheology modifiers optimize the surface tension and thixotropy of the coating, avoiding sagging or orange peel; pH adjusters maintain a neutral environment of 6.0-8.0 in the system to prevent resin degradation or filler reaction caused by acidic or alkaline conditions. In terms of process, ultrasonic dispersion effectively breaks up the agglomeration of fillers and flame retardants, low-speed stirring avoids the breakage of resin molecular chains, pH adjustment and viscosity control ensure film uniformity, and 100-mesh filtration removes large particulate impurities, ultimately forming an integrated system of stable dispersion, synergistic flame retardancy and dense film formation, thus exhibiting excellent performance in storage stability, flame retardancy, adhesion and environmental protection.

[0047] The performance of each comparative example deteriorated due to deviations in composition or process from the design of the examples: Comparative Example 1 used only ordinary zinc borate, which has a smooth surface and small specific surface area, poor compatibility with water-based resins, is prone to agglomeration and unstable dispersion, and zinc ions easily dissolve when there is no hydrophobic layer protection, resulting in loss of flame retardant in acidic environments and inability to effectively form a char layer, significantly reducing flame retardant performance and adhesion; Comparative Example 2 used only hydrophobically modified zinc borate, which, although water-resistant, has weak interfacial bonding with the resin, uneven dispersion, large viscosity change rate, and reduced flame retardant synergy; Comparative Example 3 used only hydrophilically modified zinc borate, which has poor acid resistance, accelerates zinc ion loss in acidic environments, and causes flame retardant failure; Comparative Example 4 had no modified filler, poor compatibility with resins, and easy agglomeration, resulting in low coating density, and uneven filler dispersion weakened the synergistic effect with the flame retardant; Comparative Example 5 used phosphorus-free char-forming agent polyvinyl alcohol and phosphorus-free leveling agent, resulting in low char-forming efficiency, thin char layer, weak synergistic flame retardant ability of leveling agent, and thermal release... The peak flammation rate and char residue were inferior to those of the examples; Comparative Example 6 did not add zinc borate, so it could not form an effective char layer and gas phase barrier, resulting in rapid heat release during combustion, a TTI of only 19 seconds, a char residue of only 12.4%, and poor adhesion; Comparative Example 7 did not remove the SiO2 template, resulting in a reduced specific surface area, and the agglomeration of residual SiO2 led to unstable dispersion and a large viscosity change rate; Comparative Example 8 had excessive component ratios, with too much zinc borate and too much waterborne polyurethane. Zinc borate agglomeration reduced dispersibility, resulting in high VOC content. Excessive flame retardant increased the brittleness of the coating, and after soaking in acid water, the interfacial stress concentrated, and the adhesion should decrease; Comparative Example 9 had an unbalanced component ratio, with too little zinc borate and too little char-forming agent, and a lack of leveling agent. The flame retardant and char-forming agent failed synergistically, resulting in surface defects in the coating. The adhesion was grade 5 after soaking in water, and the flammation rate deteriorated significantly. When the flame retardant was too little, the coating layer was intact but the base concentration was low, and the actual leaching concentration needed to be increased by converting it to a higher value per unit mass. In summary, the comparative example deviates from the core design of amphiphilic modified flame retardant-environmentally friendly resin-surface modified filler-synergistic process, resulting in weaker performance in all dimensions compared to the example.

[0048] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An environmentally friendly fire-retardant coating, characterized in that, By weight, it includes the following components: 5-20 parts of modified amphiphilic zinc borate composite material 5-10 parts of charring agent 50-80 parts of waterborne polyurethane 1-3 parts dispersant 0.5-2 parts of rheology modifier, Leveling agent 0.5-2 parts, 3-10 parts of modified filler 50-100 parts deionized water pH adjuster 0.1-0.5 parts, The modified amphiphilic zinc borate composite material has a double-layer core-shell structure: Core: Porous zinc borate particles; Outer shell: Amphiphilic composite coating layer, consisting of the following layers from the inside out: a) Hydrophobic silane layer; b) Hydrophilic polyether silane layer.

2. The environmentally friendly fire-retardant coating as described in claim 1, characterized in that, The modified filler is prepared by ultrasonically dispersing 5-10 parts of filler in 50-100 parts of anhydrous ethanol, adding 0.5-1 parts of polycarboxylate dispersant and 0.05-0.2 parts of silane coupling agent, stirring evenly, adding 3-5 parts of water, ball milling for 20-30 minutes, unloading, washing with deionized water until neutral, and drying to obtain the modified filler.

3. The environmentally friendly fire-retardant coating as described in claim 2, characterized in that, The filler is one or more of calcium carbonate, aluminum hydroxide, magnesium hydroxide, and magnesium carbonate, and the particle size of the filler is 1-5 μm.

4. The environmentally friendly fire-retardant coating as described in claim 1, characterized in that, The leveling agent is an organophosphorus modified organosilicon leveling agent.

5. The environmentally friendly fire-retardant coating as described in claim 1, characterized in that, The pH value of the coating is 6.0-8.

0.

6. The environmentally friendly fire-retardant coating as described in claim 1, characterized in that, The modified amphiphilic zinc borate composite material is prepared by the following steps: Step (a) Template pore formation: 5-15 parts of SiO2 microspheres are ultrasonically dispersed in 10-75 parts of anhydrous ethanol, 10-20 parts of boric acid and 5-10 parts of zinc oxide are added, and the mixture is refluxed at 75-85℃ for 2-3 hours to generate SiO2 microspheres coated with zinc borate precursor. Then, the mixture is calcined at 550-650℃ for 2-3 hours and immersed in NaOH solution to remove SiO2, thereby obtaining porous zinc borate particles. Step (b) Hydrophobic coating: 10-15 parts of porous zinc borate are ultrasonically dispersed in 50-75 parts of toluene, and 0.1-0.15 parts of heptadecafluorodecyltrimethoxysilane are added. The mixture is refluxed at 75-85°C for 2-3 hours to obtain hydrophobic particles. Step (c) Hydrophilic layer coating: Transfer 10-15 parts of hydrophobic particles to 50-75 parts of ethanol / water mixed solvent, add 0.4-0.6 parts of polyether silane, stir at 55-65℃ for 2.5-3.5 hours, wash with ethanol, dry at 50-60℃, disperse to obtain modified amphiphilic zinc borate composite material.

7. An environmentally friendly fire-retardant coating as described in claim 6, characterized in that, The SiO2 microspheres have a particle size of 50-100 nm.

8. The environmentally friendly fire-retardant coating as described in claim 6, characterized in that, In step (a), the concentration of NaOH solution is 10%-15% by mass, and the temperature at which NaOH solution removes the SiO2 template is 60°C for 2 hours.

9. The environmentally friendly fire-retardant coating as described in claim 1, characterized in that, The charring agent is ammonium polyphosphate, the dispersant is polycarboxylate dispersant, the rheology modifier is hydrophobically modified ethylene oxide polyurethane, and the pH adjuster is triethanolamine.

10. A method for preparing an environmentally friendly fire-retardant coating as described in any one of claims 1-9, characterized in that, Includes the following steps: Step (1) Add the modified amphiphilic zinc borate composite material, charring agent, dispersant and modified filler to deionized water according to the formula, and ultrasonically disperse for 10 minutes; Step (2) Add water-based polyurethane and stir at 300 rpm for 20 minutes; Step (3) Continue stirring and add rheology modifier and leveling agent; Step (4) Continue stirring and add pH adjuster to make the pH of the system 6.0-8.0 and adjust the viscosity to 5000-8000 mPa•s; Step (5) Filter and package the product through a 100-mesh sieve to obtain an environmentally friendly fire-retardant coating.

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