Flame-retardant and mildew-proof water-based wood coating and preparation method thereof

Abstract

The application relates to the technical field of water-based paint, and particularly discloses a fire-retardant and mildew-proof water-based wood paint and a preparation method thereof. The fire-retardant and mildew-proof water-based wood paint is prepared from the following raw materials in parts by weight: 40-60 parts of water-based hydroxyl polyacrylate emulsion, 10-15 parts of organic fluorine resin, 6-10 parts of boron-doped phosphorus-nitrogen intumescent flame retardant, 0.6-1.5 parts of silicon-coated slow-release mildew-proof agent, 2-5 parts of crosslinking agent, 0.5-2 parts of fumed white carbon black, 0.1-0.5 parts of defoaming agent, 2-5 parts of film-forming aid, 0.5-1 part of leveling agent, 0.01-0.1 part of fluorocarbon active agent and 20-30 parts of deionized water. The water-based paint can greatly improve the fire-retardant and mildew-proof performance simultaneously, and can meet the high-quality and high-durability wood coating requirements.

Description

Technical Field

[0001] This application relates to the field of water-based coatings technology, and more specifically, to a flame-retardant and mildew-resistant water-based wood coating and its preparation method. Background Technology

[0002] Wood coatings, as key materials for the protection and decoration of wood products, are widely used in furniture manufacturing, interior decoration, and wooden handicrafts. Their core function is to protect wood from moisture erosion, microbial growth, physical wear, and chemical corrosion, while simultaneously giving wood products an attractive appearance and feel. Water-based wood coatings, with their advantages of using water as a dispersion medium, low VOC emissions, safety and environmental friendliness, and convenient application, have become the mainstream development direction in the wood coatings industry. Water-based wood coatings mainly include water-based polyurethane, water-based acrylic, and water-based alkyd coatings. Among these, water-based polyurethane and water-based acrylic emulsions are most widely used in mid-to-high-end wood coating applications due to their excellent film-forming properties, strong adhesion, and good weather resistance.

[0003] In related technologies, patent application CN112094552A discloses a flame-retardant and stain-resistant water-based paint for wood and its preparation method. The water-based paint is prepared from raw materials containing the following components and their weight percentages: 40-60 parts of water-based hydroxyl polyacrylate emulsion, 10-15 parts of organic fluorine resin, 1-6 parts of crosslinking agent, 2-4 parts of modified rice husk ash, 0.5-2 parts of fumed silica, 3-8 parts of functionalized graphene-modified montmorillonite, 0.1-0.5 parts of defoamer, 1-6 parts of film-forming aid, 0.4-1 part of thickener, 0.3-1.2 parts of leveling agent, 0.01-0.1 parts of fluorocarbon activator, 0.1-1 parts of mildew-proof and bactericidal agent, and 15-25 parts of deionized water. This prior art, by compounding two water-based resins with inorganic flame-retardant fillers, improves the flame-retardant performance and stain resistance of water-based wood coatings to a certain extent, meeting basic environmental protection and usage requirements.

[0004] However, the water-based paints mentioned above still have some technical shortcomings in practical applications. Their overall flame retardant and mildew-proof performance is poor, making them unsuitable for complex and demanding application scenarios. Regarding flame retardancy, this technology relies solely on conventional inorganic fillers such as modified rice husk ash and graphene-modified montmorillonite to achieve a flame-retardant effect. The flame-retardant system is singular and its efficiency is limited, failing to form a continuous and dense flame-retardant protective char layer. When the paint film encounters a high-temperature open flame, it is difficult to effectively block heat transfer, thus failing to meet high-level flame retardant standards. In terms of mildew resistance, this technology adds only a small amount of conventional mildew inhibitors and fungicides. The mildew-proof component is singular, with extremely low effective content and a narrow mildew-proof coverage spectrum, only able to inhibit a few common molds. Furthermore, these mildew inhibitors generally have poor compatibility with the coating resin system, easily migrating, precipitating, and being lost in humid and warm wood-using environments. The mildew-proof effect rapidly diminishes after long-term use, making it difficult to meet the current demand for high-quality, multi-functional, and highly durable wood coatings. Summary of the Invention

[0005] To enhance the flame retardant and mildew-resistant properties of water-based wood coatings, this application provides a flame-retardant and mildew-resistant water-based wood coating and its preparation method.

[0006] This application provides a flame-retardant and mildew-resistant water-based wood coating using the following technical solution: A flame-retardant and mildew-resistant water-based wood coating comprises the following raw materials in parts by weight: 40-60 parts of water-based hydroxyl polyacrylate emulsion; 10-15 parts of organofluorine resin; 3-10 parts of hydrotalcite; 6-10 parts of boron-doped phosphorus-nitrogen intumescent flame retardant; 0.6-1.5 parts of silicone-coated slow-release antifungal agent; 2-5 parts of crosslinking agent; Fumed silica 0.5-2 parts; 0.1-0.5 parts of defoamer; 2-5 parts of film-forming aid; Leveling agent 0.5-1 part; 0.01-0.1 parts of fluorocarbon activator; 20-30 parts deionized water.

[0007] By adopting the above technical solution, a boron-doped phosphorus-nitrogen intumescent flame retardant is introduced to replace the traditional single inorganic inert flame retardant filler. Unlike traditional fillers that rely solely on physical insulation for passive flame retardancy, this application's technical solution constructs a phosphorus-nitrogen-boron multi-element composite intumescent flame retardant system. This system can trigger a highly efficient charring reaction under high-temperature conditions, forming a continuous and complete flame-retardant protective char layer on the surface of the wood coating. This effectively blocks external heat transfer and oxygen penetration, fundamentally solving the technical problems of existing technologies where the coating film is prone to continuous combustion upon exposure to open flame, has weak flame-retardant protection, and cannot meet the requirements for high-level flame retardant applications.

[0008] By introducing a silicone-coated slow-release antifungal agent, this invention specifically addresses the shortcomings of existing technologies, such as single antifungal component, narrow antibacterial spectrum, easy migration and precipitation of small-molecule antifungal agents, and rapid decline in antifungal performance under humid and hot environments. Traditional coatings only add a small amount of free antifungal and bactericidal agents, which easily lose their protective ability due to component loss and the development of microbial resistance after long-term use, making them unsuitable for the complex use scenarios of humid and warm wood products. This application adopts a core-shell structured slow-release antifungal component, which can achieve stable and slow release of antibacterial components, significantly prolonging the antifungal protection time, while broadening the range of mold inhibition, effectively improving the shortcomings of traditional water-based wood coatings in terms of poor antifungal durability and limited protective effect.

[0009] The core of this application's technical solution lies in constructing a bidirectional synergistic enhancement system of flame-retardant and mildew-resistant components, completely breaking through the industry bottleneck of existing technologies where flame-retardant fillers and mildew-resistant additives are independent, prone to interfacial antagonism, and difficult to achieve both performance goals simultaneously. The boron-doped phosphorus-nitrogen intumescent flame retardant in the formulation is rich in hydroxyl active sites on its surface, which can form stable hydrogen bonds with the inorganic shell of the silicon-coated slow-release mildew inhibitor. This allows the mildew-resistant component to be uniformly anchored within the paint film network, effectively improving the problems of uneven dispersion and easy aggregation and precipitation of mildew inhibitors in water-based resin systems. Furthermore, the fixation effect of the flame-retardant carrier further enhances the stability and long-lasting effect of the mildew-resistant system, achieving a positive enhancement of the mildew-resistant performance by the flame-retardant system.

[0010] Meanwhile, the silicone-coated slow-release mildew inhibitor can conversely enhance the flame-retardant properties of the coating, forming a synergistic closed loop of complementary functions. When the coating is heated at high temperatures, the silica shell of the mildew inhibitor undergoes a melting phase transition, and the resulting silica-based sol can precisely fill the micropores and cracks created by the expansion of the phosphorus-nitrogen flame-retardant system into char, reconstructing a dense, closed-pore, stable char layer. This significantly improves the heat insulation, oxygen barrier, and smoke suppression properties of the char layer, solving the defects of traditional phosphorus-nitrogen flame-retardant char layers that are loose, porous, and prone to cracking and peeling. While retaining the original film-forming properties, adhesion, weather resistance, and environmental protection characteristics of the coating, it simultaneously achieves a significant improvement in both flame-retardant and mildew-resistant properties, meeting the needs of high-quality, high-durability wood coating applications.

[0011] Optionally, the boron-doped phosphorus-nitrogen intumescent flame retardant is prepared by the following method: Pentaerythritol tetraphosphate, melamine, and deionized water were mixed and stirred at 800-1000 rpm for 20-30 min to obtain a phosphorus-nitrogen precursor mixture. Then, nano-boric acid was added, and stirring was continued for 20-30 min. The temperature was raised to 125-135℃, and the mixture was subjected to a constant-temperature, high-pressure hydrothermal reaction for 3-4 h. After the reaction was completed, the mixture was allowed to cool naturally to room temperature. The suspension was centrifuged, and the lower precipitate was washed 2-3 times with anhydrous ethanol. The precipitate was then dried in an oven at 60-70℃ for 12-16 h, pulverized, and passed through an 800-mesh sieve to obtain a boron-doped phosphorus-nitrogen intumescent flame retardant.

[0012] By employing the above technical solution, boron is uniformly incorporated into the phosphorus-nitrogen flame-retardant framework through hydrothermal modification. Unlike conventional simple physical compounding flame-retardant fillers, this process allows boron to be stably bound within the powder, preserving the excellent expansion and charring characteristics of the phosphorus-nitrogen system while endowing the flame-retardant powder with intrinsic inorganic antibacterial activity and abundant surface hydroxyl active sites. This preparation method can stably achieve the anchoring and dispersion effect of the flame-retardant component on the anti-mildew component, while providing a stable structural basis for the bidirectional synergistic effect of the two components. It effectively avoids the shortcomings of traditional flame-retardant fillers, such as single function, lack of synergistic activity, and only basic physical flame retardancy.

[0013] Optionally, the mass ratio of pentaerythritol tetraphosphate, melamine and deionized water is (25-30):10:(60-65).

[0014] By adopting the above technical solution, the above ratio can ensure the efficiency of char formation and the integrity of the char layer under high temperature of the powder, while ensuring sufficient hydroxyl content on the powder surface. This not only ensures the basic flame retardant performance of the coating, but also maintains the interfacial bonding ability with the silicone-coated antifungal agent. It avoids problems such as poor char formation effect and insufficient synergistic anchoring ability caused by imbalance of raw material ratio, and ensures the stable performance of the dual-function synergistic effect.

[0015] Optionally, the amount of nano-boric acid added is 1.5%-3% of the mass of the phosphorus-nitrogen precursor mixture.

[0016] Optionally, the silicone-coated slow-release antifungal agent is prepared using the following method: (1) Mix the composite antifungal agent with dichloromethane and stir at 600-800 r / min for 10-20 min to obtain a dispersion. Under stirring conditions of 8000-10000 r / min, drop the dispersion into an aqueous solution containing sodium dodecyl sulfate and emulsify for 15-20 min to form an O / W type emulsion. (2) Add ammonia water to the O / W type emulsion to adjust the pH value of the system to 8.0-8.5. After stirring evenly, slowly add tetraethyl orthosilicate. After the addition is complete, stir the hydrolysis reaction at room temperature for 2-4 hours. After the reaction is complete, centrifuge to collect the solid product, wash it with deionized water until neutral, and dry it at low temperature of 50-60℃ to obtain the silicone-coated slow-release antifungal agent.

[0017] A core-shell structured antifungal agent was prepared by combining O / W emulsion emulsification with sol-gel hydrolysis, forming a complete and dense silica coating layer on the surface of the organic antibacterial component. This structure fundamentally solves the defects of traditional free antifungal agents, such as uneven dispersion in aqueous systems, easy migration and precipitation under humid and hot environments, and poor long-term antifungal performance. At the same time, the complete silica shell structure provides structural protection for the molten reinforcement of the flame-retardant carbon layer at high temperatures, ensuring that the antifungal component has both long-term antibacterial and auxiliary flame-retardant functions, providing core support for the realization of a two-way synergistic system.

[0018] Optionally, the composite antifungal agent is composed of carbendazim and zinc pyrithione in a mass ratio of (2-3):1; the mass ratio of the composite antifungal agent to dichloromethane is 1:(10-12).

[0019] By adopting the above technical solution, carbendazim and zinc pyrithione are combined to form an organic composite antibacterial system, which effectively compensates for the shortcomings of single antifungal agents, which have a narrow antibacterial spectrum and can only inhibit a few molds, thus significantly broadening the antifungal coverage of the coating. At the same time, the reasonable ratio of antifungal agent to dichloromethane can achieve full and uniform dispersion of antibacterial components, which is conducive to the uniform coating of silica in the subsequent process, improves the structural regularity and performance stability of the slow-release antifungal agent, and further enhances the long-lasting broad-spectrum antifungal ability of the coating.

[0020] Optionally, the amount of tetraethyl orthosilicate added is 2%-5% of the mass of the O / W emulsion.

[0021] Optionally, the organofluorine resin is selected from one of hexafluorobutyl acrylate, hexafluoroisopropyl acrylate, or hexafluoroisopropyl methacrylate.

[0022] Optionally, the film-forming aid is a mixture of dipropylene glycol butyl ether and tripropylene glycol methyl ether in a mass ratio of (2-3):1.

[0023] This application also provides a method for preparing a flame-retardant and mildew-resistant water-based wood coating, using the following technical solution: A method for preparing a flame-retardant and mildew-resistant water-based wood coating includes the following steps: S1. Add deionized water, fluorocarbon activator, leveling agent and defoamer into a mixing tank and stir at 400-500 r / min for 5-8 min to obtain the additive premix; S2. Add waterborne hydroxyl polyacrylate emulsion and organic fluorine resin to the premixed additive solution, heat to 30-35℃, stir at 600-800 r / min for 10-12 min, then add hydrotalcite, fumed silica and boron-doped phosphorus nitrogen intumescent flame retardant, continue stirring for 25-30 min, then add silicone-coated slow-release mildew inhibitor, film-forming aid and crosslinking agent, stir at 300-500 r / min for 10-20 min to obtain flame-retardant and mildew-resistant waterborne wood coating.

[0024] By employing a step-by-step process design—including premixing of additives, resin fusion, high-speed dispersion of flame-retardant powder, and low-speed compounding of anti-mildew components—optimal dispersion of different functional components is achieved. This process effectively disperses flame-retardant fillers, ensuring uniform distribution of the flame-retardant system. Simultaneously, it avoids the problem of high-speed shearing damaging the core-shell structure of the anti-mildew agent, maximizing the preservation of the synergistic functional characteristics of the dual-core components. This solves the problems of uneven component dispersion, damaged functional structures, and reduced dual-protection performance in traditional preparation processes, ensuring stable and reliable performance of the finished coating.

[0025] In summary, this application has the following beneficial effects: 1. This application uses a boron-doped phosphorus-nitrogen intumescent flame retardant to replace the conventional inert inorganic flame retardant fillers in traditional coatings, effectively solving the technical defects of existing flame retardant systems, poor charring effect, and low flame retardant rating. Traditional water-based wood coatings rely solely on ordinary inorganic fillers to achieve passive physical heat insulation and flame retardancy, failing to form a stable and continuous protective char layer. At high temperatures, they are unable to effectively block heat and oxygen transfer, resulting in weak fire resistance. This application constructs a phosphorus-nitrogen-boron multi-component composite intumescent flame retardant system, which can rapidly trigger a charring reaction at high temperatures, forming a dense and complete flame-retardant char layer on the paint film surface, significantly improving the coating's heat insulation, oxygen barrier, and smoke suppression capabilities. Simultaneously, the flame retardant surface is rich in numerous hydroxyl active sites, which can form a stable binding effect with anti-mildew components, effectively improving the problem of easy aggregation and uneven dispersion of anti-mildew agents in the coating system. This enhances the stability of the anti-mildew system from the carrier structure level, achieving a synergistic benefit of flame retardant components on anti-mildew performance.

[0026] 2. This application preferably employs a silicone-coated slow-release composite antifungal agent, effectively solving the shortcomings of existing technologies such as single antifungal component, narrow antibacterial spectrum, easy migration and loss of small molecule antifungal agents, and poor durability. Traditional coatings only add ordinary free antifungal agents, which not only have limited antibacterial species and are difficult to adapt to the complex and humid environment of wood use, but are also prone to precipitation and failure under long-term humid and hot conditions, resulting in rapid decay of antifungal effect. This application adopts a multi-component composite antibacterial core combined with a silica core-shell coating structure, which greatly broadens the range of mold inhibition, while achieving stable slow release of antibacterial components, eliminating the problem of antifungal component loss, and maintaining the antifungal performance of the paint film for a long time. In addition, the silicone-based shell of the antifungal agent can melt under high temperature conditions to generate silicone-based sol, which can fill the micropores of the flame-retardant char layer, repair defects in the char layer, and conversely help improve the flame-retardant stability and flame-retardant rating of the coating.

[0027] 3. This application, through a dual-core functional component synergistic system combined with an optimized formulation system and a step-by-step preparation process, completely solves the industry technical bottleneck of existing technologies where flame retardant and mildew-proof properties are mutually antagonistic and difficult to achieve simultaneously. In existing technologies, flame-retardant fillers and mildew-proof additives are independent and have poor compatibility, and the two functions cannot be simultaneously and efficiently exerted. This application relies on the structural compatibility of flame-retardant and mildew-proof components to construct a synergistic closed-loop system that provides stable mildew protection at room temperature and high-efficiency flame retardancy at high temperatures. The two functional components mutually enhance each other without performance antagonism. At the same time, with a suitable resin and additive system and a segmented dispersion process, while fully preserving the excellent film-forming properties, adhesion, weather resistance, and environmental performance of the coating, it simultaneously enhances the dual core properties of flame retardancy and mildew prevention, effectively overcoming the defects of poor comprehensive protective performance and short service life of traditional water-based wood coatings, and adapting to the needs of high-quality and high-durability wood coating applications. Detailed Implementation

[0028] The present application will be further described in detail below with reference to the embodiments.

[0029] Preparation example of boron-doped phosphorus-nitrogen intumescent flame retardant Preparation Example 1 Boron-doped phosphorus-nitrogen intumescent flame retardant was prepared using the following method: 25g of pentaerythritol tetraphosphate, 10g of melamine, and 60g of deionized water were mixed and stirred at 800 rpm for 20 min to obtain a phosphorus-nitrogen precursor mixture. Nano-boric acid (1.5% by mass of the total phosphorus-nitrogen precursor mixture) was added to the mixture, and stirring continued for 20 min. The mixture was heated to 125℃ and subjected to a constant-temperature, high-pressure hydrothermal reaction for 3 h. After the reaction, the mixture was allowed to cool naturally to room temperature, centrifuged to obtain the precipitate, washed twice with anhydrous ethanol, dried in a 60℃ oven for 12 h, pulverized, and passed through an 800-mesh sieve to obtain a boron-doped phosphorus-nitrogen intumescent flame retardant.

[0030] Preparation Example 2 Boron-doped phosphorus-nitrogen intumescent flame retardant was prepared using the following method: 27.5 g of pentaerythritol tetraphosphate, 10 g of melamine, and 62.5 g of deionized water were mixed and stirred at 900 rpm for 25 min to obtain a phosphorus-nitrogen precursor mixture. Nano-boric acid (2.25% by mass of the total phosphorus-nitrogen precursor mixture) was added to the mixture, and stirring continued for another 25 min. The mixture was heated to 130 °C and subjected to a constant-temperature, high-pressure hydrothermal reaction for 3.5 h. After the reaction was completed, the mixture was allowed to cool naturally to room temperature, centrifuged to obtain the precipitate, washed twice with anhydrous ethanol, dried in a 65 °C oven for 14 h, pulverized, and passed through an 800-mesh sieve to obtain a boron-doped phosphorus-nitrogen intumescent flame retardant.

[0031] Preparation Example 3 Boron-doped phosphorus-nitrogen intumescent flame retardant was prepared using the following method: 30g of pentaerythritol tetraphosphate, 10g of melamine, and 65g of deionized water were mixed and stirred at 1000 rpm for 30 min to obtain a phosphorus-nitrogen precursor mixture. Nano-boric acid (3% by mass of the total phosphorus-nitrogen precursor mixture) was added to the mixture, and stirring continued for another 30 min. The mixture was heated to 135℃ and subjected to a constant-temperature, high-pressure hydrothermal reaction for 4 h. After the reaction was completed, the mixture was allowed to cool naturally to room temperature, centrifuged to obtain the precipitate, washed three times with anhydrous ethanol, dried in a 70℃ oven for 16 h, pulverized, and passed through an 800-mesh sieve to obtain a boron-doped phosphorus-nitrogen intumescent flame retardant.

[0032] Silicone-coated slow-release antifungal agent Preparation Example 4 The silicone-coated slow-release antifungal agent was prepared using the following method: (1) A compound fungicide was prepared by mixing carbendazim and zinc pyrithione at a mass ratio of 2:1. The compound fungicide was then mixed with dichloromethane at a mass ratio of 1:10 and stirred at 600 r / min for 10 min to obtain a dispersion. Under stirring conditions of 8000 r / min, the dispersion was added dropwise to an aqueous solution of sodium dodecyl sulfate and emulsified for 15 min to form an O / W type emulsion.

[0033] (2) Add ammonia water dropwise to the O / W type emulsion to adjust the pH of the system to 8.0, and slowly add tetraethyl orthosilicate accounting for 2% of the total mass of the O / W type emulsion. The hydrolysis reaction is carried out at room temperature with stirring for 2 hours. After the reaction is completed, the solid product is collected by centrifugation, washed with deionized water until neutral, and dried at 50°C to obtain the silicone-coated slow-release antifungal agent.

[0034] Preparation Example 5 The silicone-coated slow-release antifungal agent was prepared using the following method: (1) A compound fungicide was prepared by mixing carbendazim and zinc pyrithione at a mass ratio of 2.5:1. The compound fungicide was then mixed with dichloromethane at a mass ratio of 1:11 and stirred at 700 r / min for 15 min to obtain a dispersion. Under stirring conditions of 9000 r / min, the dispersion was added dropwise to an aqueous solution of sodium dodecyl sulfate and emulsified for 18 min to form an O / W type emulsion.

[0035] (2) Add ammonia water dropwise to the O / W type emulsion to adjust the pH of the system to 8.3, and slowly add tetraethyl orthosilicate accounting for 3.5% of the total mass of the O / W type emulsion. The hydrolysis reaction is carried out at room temperature with stirring for 3 hours. After the reaction is completed, the solid product is collected by centrifugation, washed with deionized water until neutral, and dried at 55°C to obtain the silicone-coated slow-release antifungal agent.

[0036] Preparation Example 6 The silicone-coated slow-release antifungal agent was prepared using the following method: (1) A compound fungicide was prepared by mixing carbendazim and zinc pyrithione at a mass ratio of 3:1. The compound fungicide was then mixed with dichloromethane at a mass ratio of 1:12 and stirred at 800 r / min for 20 min to obtain a dispersion. Under stirring conditions of 10000 r / min, the dispersion was added dropwise to an aqueous solution of sodium dodecyl sulfate and emulsified for 20 min to form an O / W type emulsion.

[0037] (2) Add ammonia water dropwise to the O / W type emulsion to adjust the pH of the system to 8.5, and slowly add 5% tetraethyl orthosilicate of the total mass of the O / W type emulsion. The hydrolysis reaction is carried out at room temperature with stirring for 4 hours. After the reaction is completed, the solid product is collected by centrifugation, washed with deionized water until neutral, and dried at 60°C to obtain the silicone-coated slow-release antifungal agent.

[0038] Example Example 1 A flame-retardant and mildew-resistant water-based wood coating, the raw material components and formulation of which are shown in Table 1. The water-based hydroxyl polyacrylate emulsion has a solid content of 40±1%, the organic fluorine resin is hexafluorobutyl acrylate, the hydrotalcite is zinc aluminum hydrotalcite, the boron-doped phosphorus-nitrogen intumescent flame retardant is the boron-doped phosphorus-nitrogen intumescent flame retardant prepared in Preparation Example 1, the silicone-coated slow-release mildew inhibitor is the silicone-coated slow-release mildew inhibitor prepared in Preparation Example 4, the crosslinking agent is water-based hexamethylene diisocyanate, the defoamer is DF-58, the film-forming aid is a mixture of dipropylene glycol butyl ether and tripropylene glycol methyl ether in a mass ratio of 2:1, the leveling agent is BYK345 silicone leveling agent, and the fluorocarbon activator is FSO-100.

[0039] A method for preparing a flame-retardant and mildew-resistant water-based wood coating includes the following steps: S1. Add deionized water, fluorocarbon activator, leveling agent and defoamer into a mixing tank and stir at 400 r / min for 5 min to obtain the additive premix; S2. Add waterborne hydroxyl polyacrylate emulsion and organic fluorine resin to the premixed additive solution, heat to 30°C, stir at 600 r / min for 10 min, then add hydrotalcite, fumed silica and boron-doped phosphorus nitrogen expanding flame retardant, continue stirring for 25 min, then add silicone-coated slow-release mildew inhibitor, film-forming aid and crosslinking agent, stir at 300 r / min for 10 min to obtain flame-retardant and mildew-resistant waterborne wood coating.

[0040] Example 2 A flame-retardant and mildew-resistant water-based wood coating, the raw material components and formulation of which are shown in Table 1. The water-based hydroxyl polyacrylate emulsion has a solid content of 40±1%, the organic fluorine resin is hexafluoroisopropyl acrylate, the hydrotalcite is zinc aluminum hydrotalcite, the boron-doped phosphorus-nitrogen intumescent flame retardant is the boron-doped phosphorus-nitrogen intumescent flame retardant prepared in Preparation Example 2, the silicone-coated slow-release mildew inhibitor is the silicone-coated slow-release mildew inhibitor prepared in Preparation Example 5, the crosslinking agent is water-based hexamethylene diisocyanate, the defoamer is DF-58, the film-forming aid is a mixture of dipropylene glycol butyl ether and tripropylene glycol methyl ether in a mass ratio of 2.5:1, the leveling agent is BYK345 silicone leveling agent, and the fluorocarbon activator is FSO-100.

[0041] A method for preparing a flame-retardant and mildew-resistant water-based wood coating includes the following steps: S1. Add deionized water, fluorocarbon activator, leveling agent and defoamer into a mixing tank and stir at 450 r / min for 6 min to obtain the additive premix; S2. Add waterborne hydroxyl polyacrylate emulsion and organic fluorine resin to the premixed additive solution, heat to 32°C, stir at 700 r / min for 11 min, then add hydrotalcite, fumed silica and boron-doped phosphorus nitrogen expanding flame retardant, continue stirring for 28 min, then add silicone-coated slow-release mildew inhibitor, film-forming aid and crosslinking agent, stir at 400 r / min for 15 min to obtain flame-retardant and mildew-resistant waterborne wood coating.

[0042] Example 3 A flame-retardant and mildew-resistant waterborne wood coating, the raw material components and formulation of which are shown in Table 1. The waterborne hydroxyl polyacrylate emulsion has a solid content of 40±1%, the organic fluorine resin is hexafluoroisopropyl acrylate, the hydrotalcite is zinc aluminum hydrotalcite, the boron-doped phosphorus-nitrogen intumescent flame retardant is the boron-doped phosphorus-nitrogen intumescent flame retardant prepared in Preparation Example 3, the silicone-coated slow-release mildew inhibitor is the silicone-coated slow-release mildew inhibitor prepared in Preparation Example 6, the crosslinking agent is waterborne hexamethylene diisocyanate, the defoamer is DF-58, the film-forming aid is a mixture of dipropylene glycol butyl ether and tripropylene glycol methyl ether in a mass ratio of 3:1, the leveling agent is BYK345 silicone leveling agent, and the fluorocarbon activator is FSO-100.

[0043] A method for preparing a flame-retardant and mildew-resistant water-based wood coating includes the following steps: S1. Add deionized water, fluorocarbon activator, leveling agent and defoamer into a mixing tank and stir at 500 r / min for 8 min to obtain the additive premix; S2. Add waterborne hydroxyl polyacrylate emulsion and organic fluorine resin to the premixed additive solution, heat to 35°C, stir at 800 r / min for 12 min, then add hydrotalcite, fumed silica and boron-doped phosphorus nitrogen expanding flame retardant, continue stirring for 30 min, then add silicone-coated slow-release mildew inhibitor, film-forming aid and crosslinking agent, stir at 500 r / min for 20 min to obtain flame-retardant and mildew-resistant waterborne wood coating.

[0044] Table 1. Raw material components and proportions (g) of water-based wood coatings in Examples 1-3

[0045] Example 4 A flame-retardant and mildew-resistant water-based wood coating differs from Example 3 in that the boron-doped phosphorus-nitrogen expanding flame retardant in this example is the boron-doped phosphorus-nitrogen expanding flame retardant prepared in Preparation Example 2.

[0046] Example 5 A flame-retardant and mildew-resistant water-based wood coating differs from Example 3 in that the silicone-coated slow-release mildew inhibitor in this example is the silicone-coated slow-release mildew inhibitor prepared in Preparation Example 5.

[0047] Example 6 A flame-retardant and mildew-resistant water-based wood coating differs from Example 3 in that the organic fluorine resin used in this example is hexafluorobutyl acrylate.

[0048] Example 7 A flame-retardant and mildew-resistant water-based wood coating differs from Example 3 in that the film-forming aid used in this example is dipropylene glycol butyl ether.

[0049] Comparative Example Comparative Example 1 A water-based coating was prepared according to Example 1 in the patent application document with publication number CN112094552A entitled "A Flame-Retardant and Sewage-Resistant Paint for Wood and Its Preparation Method".

[0050] Comparative Example 2 A flame-retardant and mildew-resistant water-based wood coating differs from Example 3 in that: in this comparative example, an equal amount of ammonium polyphosphate is used instead of boron-doped phosphorus-nitrogen expanding flame retardant.

[0051] Comparative Example 3 A flame-retardant and mildew-resistant water-based wood coating differs from Example 3 in that an equal amount of commercially available BEK-569 bactericide is used instead of the silicone-coated slow-release mildew inhibitor in this comparative example.

[0052] Comparative Example 4 A flame-retardant and mildew-resistant water-based wood coating differs from Example 3 in that zinc-aluminum hydrotalcite is not added in this comparative example.

[0053] Performance testing (1) Limiting Oxygen Index (LOI) and Vertical Flame Retardancy Rating Testing standards: GB / T 2406.2-2009, GB / T 2408-2021. Operating method: Cut the cured paint film sample into standard specimens. Use an oxygen index tester to test the minimum oxygen concentration required for sustained combustion. Use a vertical combustion tester to observe the burning time, dripping, and char layer state of the specimens to determine the flame retardant rating. The ratings, from highest to lowest, are V-0, V-1, V-2, and no rating. The results are shown in Table 2.

[0054] (2) Initial antibacterial rate at room temperature The antibacterial rate of water-based coating samples was tested according to the operating method specified in GB / T 21866-2008, and the results are shown in Table 2.

[0055] (3) Antibacterial rate after humid heat aging Operating method: The sample was placed in a humid heat aging chamber at 60℃ and 90% humidity for 200 hours to simulate a long-term humid and harsh use environment. After removal, the antibacterial rate of the water-based coating sample was tested according to the operating method specified in GB / T 21866-2008. The results are shown in Table 2.

[0056] Table 2 Experimental Results

[0057] As shown in Table 2, the limiting oxygen index (LOI) of all samples in the embodiments was above 32.4%, and all reached the V-0 high flame retardant rating, demonstrating excellent flame retardant performance. The water-based coating in Comparative Example 1 relied solely on inorganic fillers for passive physical insulation, failing to form a continuous and dense char layer. Its LIO was only 25.3%, resulting in no flame retardant rating and weak flame retardant protection. Comparative Example 2 used ordinary ammonium polyphosphate instead of the boron-doped phosphorus-nitrogen intumescent flame retardant, lacking the synergistic effect of boron modification. The resulting char layer was loose and porous with poor stability, only reaching the V-2 flame retardant standard. Comparative Example 4 did not add hydrotalcite, resulting in insufficient film density and an inability to effectively block heat and oxygen penetration, significantly deteriorating its flame retardant performance. This demonstrates that the boron-doped modified multi-element flame retardant system of this application can rapidly trigger a highly efficient charring reaction at high temperatures. Combined with the pore-filling and reinforcing effect of the silicon-based components, it significantly improves the heat insulation, oxygen barrier, and smoke suppression performance of the char layer, fundamentally enhancing the flame retardant rating and high-temperature protective stability of the coating.

[0058] Antimicrobial and mildew-resistant data show that the initial antibacterial rate of each embodiment is higher than 99.26%. After harsh environmental treatment with humid heat aging, the antibacterial rate can still be maintained above 97.15%, demonstrating outstanding long-term stability in antimicrobial and mildew-resistant properties. Comparative Example 1, a traditional coating, only adds conventional free antimicrobial components. The component is singular and has poor compatibility with the resin system, resulting in an initial antibacterial rate of only 82.37%. Under long-term humid heat conditions, a large amount of antimicrobial components are lost, and the antibacterial rate drops significantly to 53.62% after aging, essentially losing its antimicrobial protection capability. Comparative Example 3, replaced with a commercially available common bactericide, lacks the protection of a core-shell slow-release structure and the anchoring effect of flame-retardant powder. Under humid heat conditions, the small-molecule antimicrobial components rapidly precipitate and fail, resulting in an antimicrobial rate of only 61.75% after aging. This fully demonstrates that the core-shell slow-release structure combined with hydrogen bond anchoring in this application can stably lock in the antibacterial components, completely improving the defect of rapid decline in the antimicrobial performance of traditional coatings.

[0059] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A flame-retardant and mildew-resistant water-based wood coating, characterized in that, The raw materials include the following parts by weight: 40-60 parts of water-based hydroxyl polyacrylate emulsion; 10-15 parts of organofluorine resin; 3-10 parts of hydrotalcite; 6-10 parts of boron-doped phosphorus-nitrogen intumescent flame retardant; 0.6-1.5 parts of silicone-coated slow-release antifungal agent; 2-5 parts of crosslinking agent; Fumed silica 0.5-2 parts; 0.1-0.5 parts of defoamer; 2-5 parts of film-forming aid; Leveling agent 0.5-1 part; 0.01-0.1 parts of fluorocarbon activator; 20-30 parts deionized water.

2. The flame-retardant and mildew-resistant water-based wood coating according to claim 1, characterized in that, The boron-doped phosphorus-nitrogen expandable flame retardant was prepared by the following method: Pentaerythritol tetraphosphate, melamine, and deionized water were mixed and stirred at 800-1000 rpm for 20-30 min to obtain a phosphorus-nitrogen precursor mixture. Then, nano-boric acid was added, and stirring was continued for 20-30 min. The temperature was raised to 125-135℃, and the mixture was subjected to a constant-temperature, high-pressure hydrothermal reaction for 3-4 h. After the reaction was completed, the mixture was allowed to cool naturally to room temperature. The suspension was centrifuged, and the lower precipitate was washed 2-3 times with anhydrous ethanol. The precipitate was then dried in an oven at 60-70℃ for 12-16 h, pulverized, and passed through an 800-mesh sieve to obtain a boron-doped phosphorus-nitrogen intumescent flame retardant.

3. The flame-retardant and mildew-resistant water-based wood coating according to claim 2, characterized in that: The mass ratio of pentaerythritol tetraphosphate, melamine and deionized water is (25-30):10:(60-65).

4. The flame-retardant and mildew-resistant water-based wood coating according to claim 2, characterized in that: The amount of nano-boric acid added is 1.5%-3% of the mass of the phosphorus and nitrogen precursor mixture.

5. The flame-retardant and mildew-resistant water-based wood coating according to claim 1, characterized in that, The silicon-coated slow-release antifungal agent was prepared using the following method: (1) Mix the composite antifungal agent with dichloromethane and stir at 600-800 r / min for 10-20 min to obtain a dispersion. Under stirring conditions of 8000-10000 r / min, drop the dispersion into an aqueous solution containing sodium dodecyl sulfate and emulsify for 15-20 min to form an O / W type emulsion. (2) Add ammonia water to the O / W type emulsion to adjust the pH value of the system to 8.0-8.

5. After stirring evenly, slowly add tetraethyl orthosilicate. After the addition is complete, stir the hydrolysis reaction at room temperature for 2-4 hours. After the reaction is complete, centrifuge to collect the solid product, wash it with deionized water until neutral, and dry it at low temperature of 50-60℃ to obtain the silicone-coated slow-release antifungal agent.

6. The flame-retardant and mildew-resistant water-based wood coating according to claim 1, characterized in that: The composite antifungal agent is composed of carbendazim and zinc pyrithione in a mass ratio of (2-3):1; the mass ratio of the composite antifungal agent to dichloromethane is 1:(10-12).

7. The flame-retardant and mildew-resistant water-based wood coating according to claim 1, characterized in that: The amount of tetraethyl orthosilicate added is 2%-5% of the mass of the O / W emulsion.

8. The flame-retardant and mildew-resistant water-based wood coating according to claim 1, characterized in that: The organofluorine resin is selected from one of hexafluorobutyl acrylate, hexafluoroisopropyl acrylate, or hexafluoroisopropyl methacrylate.

9. The flame-retardant and mildew-resistant water-based wood coating according to claim 1, characterized in that: The film-forming aid is a mixture of dipropylene glycol butyl ether and tripropylene glycol methyl ether in a mass ratio of (2-3):

1.

10. A method for preparing a flame-retardant and mildew-resistant water-based wood coating according to any one of claims 1-9, characterized in that, Includes the following steps: S1. Add deionized water, fluorocarbon activator, leveling agent and defoamer into a mixing tank and stir at 400-500 r / min for 5-8 min to obtain the additive premix; S2. Add waterborne hydroxyl polyacrylate emulsion and organic fluorine resin to the premixed additive solution, heat to 30-35℃, stir at 600-800 r / min for 10-12 min, then add hydrotalcite, fumed silica and boron-doped phosphorus nitrogen intumescent flame retardant, continue stirring for 25-30 min, then add silicone-coated slow-release mildew inhibitor, film-forming aid and crosslinking agent, stir at 300-500 r / min for 10-20 min to obtain flame-retardant and mildew-resistant waterborne wood coating.

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