Super-hydrophobic flame-retardant coating with high sunlight reflection as well as preparation method and application of super-hydrophobic flame-retardant coating

Abstract

The invention relates to a super-hydrophobic flame-retardant coating with high sunlight reflection and a preparation method and application thereof.According to the coating, firstly, a copolymer Poly (MMA-r-VPA-r-ADH-b-FTMAC), gas-phase nanoparticles, acetone and water are mixed to obtain a coating suspension, then the coating suspension is sprayed to a base material and dried at the room temperature, and the super-hydrophobic flame-retardant coating with high sunlight reflection is obtained. The rapid evaporation of the volatile acetone induces the polymer to be separated from water, and the porous high-sunlight-reflection coating is formed after drying. Wherein the copolymer Poly (MMA-r-VPA-r-ADH-b-FTMAC) is prepared from a bonding functional monomer, methyl methacrylate, ethylene phosphonic acid and 2-(perfluorohexyl) ethyl methacrylate by virtue of a reversible addition-fragmentation chain transfer (RAFT) polymerization technology. Compared with the prior art, the reflectivity can reach 95%. The obtained coating has excellent super-hydrophobicity, the static contact angle reaches 151 degrees, and the coating shows excellent flame retardance and can reach the UL-94 V-0 grade.

Description

Technical Field

[0001] The present invention relates to the technical field of coatings, and particularly to a superhydrophobic flame-retardant coating with high solar reflectance, and a preparation method and application thereof. Background Art

[0002] With the increasingly severe global energy crisis and climate change problems, energy conservation and environmental protection have become an important development direction in the construction industry. Against this background, the energy efficiency and safety of building materials have received extensive attention. Wood, as a commonly used building material, has good natural aesthetics and excellent structural strength, but its flammability and poor thermal insulation performance limit its wide application in scenarios such as building facades. Especially in the peripheral coating treatment of wood structures, traditional coatings mainly focus on flame retardancy and lack comprehensive consideration of solar reflectance, thermal management, and long-term weather resistance, making it difficult to meet the multi-functional requirements of modern buildings for coating materials. In building exterior wall coating technology, high solar reflectance coatings can effectively reduce the air conditioning energy consumption of buildings, especially in hot climate conditions, and improve the energy efficiency performance of buildings. However, most of the existing high reflectance coatings only focus on the reflection ability and lack consideration of hydrophobicity and fire resistance.

[0003] CN114752236A discloses a method for preparing a high reflectance wear-resistant superhydrophobic coating by surface modification of GCC micron particles and TiO2 nanoparticles using room temperature vulcanized silicone rubber (RTV) and tetraethyl orthosilicate (TEOS). The coating is prepared on the cement surface by spraying process and can effectively improve the reflectance and wear resistance. However, the flame retardant performance of the coating has not been fully concerned, and it may not be able to effectively reduce the spread rate of fire in case of fire, thus posing a potential hazard to public safety. CN116218364A discloses a near-infrared high reflectance radiative cooling coating and a preparation method thereof. The coating uses n-hexane as a solvent, PDMS as a film-forming substance, and is combined with TiO2 and Y2O3 as fillers, and can effectively reflect solar radiation, thus achieving a radiative cooling effect. However, although such coatings perform well in solar reflectance, their main component PDMS has low flame retardant performance.

[0004] Therefore, developing a coating material that integrates high solar reflectance, superhydrophobicity, and flame retardant performance, which can not only effectively improve the energy utilization efficiency of buildings but also enhance the safety and durability of wood, has become an urgent technical problem to be solved. Summary of the Invention

[0005] The purpose of the present invention is to provide a superhydrophobic flame-retardant coating with high solar reflectance, and a preparation method and application thereof. The coating has a high solar reflectance, superhydrophobicity, and excellent flame retardant performance.

[0006] The object of the present invention can be achieved by the following technical solutions:

[0007] On the one hand, the present invention provides a superhydrophobic flame-retardant coating with high sunlight reflectivity. The raw materials of the coating include the following components: copolymer Poly (MMA-r-VPA-r-ADH-b-FTMAC), fumed nanoparticles, acetone, and water. The structural formula of the copolymer Poly (MMA-r-VPA-r-ADH-b-FTMAC) is as follows: ; Among them, ADH is an adhesive functional monomer, including any one of vinyl acetate, n-butyl methacrylate, and 2-ethylhexyl acrylate. The value ranges of x, y, z, and k are respectively: 70 < x < 250, 35 < y < 100, 25 < z < 100, and 10 < k < 100.

[0008] Preferably, in the structural formula, r and b respectively represent that the monomers on their right sides are introduced by random copolymerization (r) or block copolymerization (b).

[0009] Preferably, the copolymer Poly (MMA-r-VPA-r-ADH-b-FTMAC) is prepared by reversible addition-fragmentation chain transfer polymerization (RAFT) technology using an adhesive functional monomer (ADH), methyl methacrylate (MMA), vinylphosphonic acid (VPA), and 2-(perfluorohexyl)ethyl methacrylate (FTMAC).

[0010] Preferably, the molar parts of each monomer raw material of the copolymer Poly (MMA-r-VPA-r-ADH-b-FTMAC) are as follows: Adhesive functional monomer 15 - 20 parts; Methyl methacrylate 40 - 60 parts; Vinylphosphonic acid 15 - 25 parts; 2-(Perfluorohexyl)ethyl methacrylate 3 - 25 parts.

[0011] Preferably, the fumed nanoparticles include one or two of fumed silica, fumed titanium dioxide, and fumed aluminum oxide.

[0012] Preferably, the mass ratio of the copolymer Poly (MMA-r-VPA-r-ADH-b-FTMAC) to the fumed nanoparticles is 1:(0.05 - 0.45).

[0013] Preferably, the mass ratio of the sum of the mass of the copolymer Poly (MMA-r-VPA-r-ADH-b-FTMAC) and the fumed nanoparticles to acetone and water is (1.05 - 1.45):(5 - 10):(0.5 - 1).

[0014] Preferably, the thickness of the coating is not less than 50 μm. The coating has a porous structure with a porosity of 30% - 70% and a specific surface area of 50 - 200 m 2 / g, and the pore size is 0.5 - 5 μm.

[0015] In a second aspect, the present invention provides a method for preparing the superhydrophobic flame - retardant coating with high sunlight reflectivity, comprising the following steps: S1: Prepare the copolymer Poly (MMA - r - VPA - r - ADH - b - FTMAC); S2: Dissolve and disperse the copolymer Poly (MMA - r - VPA - r - ADH - b - FTMAC) and gas - phase nanoparticles in a mixed solvent of acetone and water to prepare a coating suspension; S3: Spray the coating suspension onto the surface of the substrate by a spraying process and dry it at room temperature to obtain the coating.

[0016] Preferably, step S1 specifically includes the following steps: S1.1: Mix the bonding functional monomer, methyl methacrylate, vinylphosphonic acid, chain - transfer agent with acetone to obtain a mixed solution; S1.2: Add an initiator to the mixed solution, heat and stir the reaction under an inert gas atmosphere, and then perform a quenching treatment to obtain a first product solution; S1.3: Drop the first product solution into ether to precipitate a solid intermediate product; S1.4: Dissolve the solid intermediate product in acetone, add 2 - (perfluorohexyl) ethyl methacrylate and an initiator, heat and stir the reaction under an inert gas atmosphere, and then perform a quenching treatment to obtain a second product solution; S1.5: Drop the second product solution into ether to precipitate the copolymer Poly (MMA - r - VPA - r - ADH - b - FTMAC).

[0017] Preferably, in step S1.1, the dosage of the chain - transfer agent is 0.02% - 0.1% of the total molar amount of the bonding functional monomer, methyl methacrylate, and vinylphosphonic acid.

[0018] Preferably, in step S1.1, the total concentration of the bonding functional monomer, methyl methacrylate, and vinylphosphonic acid in the mixed solution is set to 45wt% - 60wt%.

[0019] Preferably, in step S1.1, the chain - transfer agent includes 2 - [dodecylthio(thiocarbonyl)thio] - 2 - methylpropanoic acid.

[0020] Preferably, in step S1.2, the initiator includes azobisisobutyronitrile.

[0021] Preferably, in step S1.2, the inert gas includes nitrogen, the heating temperature is 60-80 °C, the stirring speed is 500-1000 rpm, and the time is 12-24 h.

[0022] Preferably, in step S1.2, the temperature of the quenching treatment is -4-5 °C, and more preferably 0 °C.

[0023] Preferably, in step S1.2, the dosage of the initiator is 5-50% of the molar amount of the chain transfer agent in step S1.1.

[0024] Preferably, in step S1.3, the volume ratio of the ether to the first product solution is greater than 8, and more preferably 8:1-20:1.

[0025] Preferably, in step S1.4, the sum of the masses of the solid intermediate product and 2-(perfluorohexyl)ethyl methacrylate accounts for 45-60% of the sum of the masses of the solid intermediate product, 2-(perfluorohexyl)ethyl methacrylate, and acetone.

[0026] More preferably, in step S1.4, the mass of 2-(perfluorohexyl)ethyl methacrylate accounts for 5-16% of the sum of the masses of the solid intermediate product, 2-(perfluorohexyl)ethyl methacrylate, and acetone.

[0027] Preferably, in step S1.4, the inert gas includes nitrogen, the heating temperature is 60-80 °C, the stirring speed is 500-1000 rpm, the time is 8-16 h, and more preferably 12 h.

[0028] Preferably, in step S1.4, the temperature of the quenching treatment is -4-5 °C, and more preferably 0 °C.

[0029] Preferably, in step S1.4, the dosage of the initiator is 5-50% of the molar amount of the chain transfer agent in step S1.1.

[0030] Preferably, in step S1.4, the initiator includes azobisisobutyronitrile.

[0031] Preferably, in step S1.5, the volume ratio of the ether to the second product solution is greater than 8, and more preferably 8:1-20:1.

[0032] Preferably, in step S3, the substrate includes construction wood.

[0033] Preferably, in step S3, the parameters of the spraying process are as follows: the spray gun pressure is 0.3 - 0.6 MPa, the spraying distance is 100 - 300 mm, and the moving speed of the spray gun is 0.05 - 0.5 m / s.

[0034] Preferably, in step S3, the time for drying at room temperature is 4 - 8 h, and more preferably 6 h.

[0035] In the present invention, during the drying process at room temperature, the rapid evaporation of volatile acetone in the mixed solvent will promote the phase separation of the copolymer and water, and a porous coating is formed after the complete evaporation of water.

[0036] Preferably, the method for preparing the highly sunlight - reflective superhydrophobic flame - retardant coating includes the following steps: S1: Mix a bonding functional monomer, methyl methacrylate, vinyl phosphonic acid, a chain - transfer agent 2 - [dodecylthio(thiocarbonyl)thio] - 2 - methylpropanoic acid with an acetone solvent; wherein, the amount of the chain - transfer agent 2 - [dodecylthio(thiocarbonyl)thio] - 2 - methylpropanoic acid is 0.02% - 0.1% of the total molar amount of the bonding functional monomer, methyl methacrylate, and vinyl phosphonic acid; the total concentration of the bonding functional monomer, methyl methacrylate, and vinyl phosphonic acid monomers in the mixed solution is set to 45wt% - 60wt%. S2: Add an initiator azobisisobutyronitrile to the S1 mixed solution, heat it to 60 - 80°C under a nitrogen atmosphere and stir for 12 - 24 h, and then quickly cool it to 0°C; the amount of the initiator azobisisobutyronitrile is 5 - 50% of the molar amount of the chain - transfer agent in S1. S3: Drop the product solution obtained in S2 into diethyl ether with a volume eight times higher to precipitate a solid intermediate product. S4: Dissolve the intermediate product obtained in S3 in an acetone solvent again, add a monomer 2 - (perfluorohexyl)ethyl methacrylate and an initiator azobisisobutyronitrile, heat it to 60 - 80°C under a nitrogen atmosphere and stir - react for 12 h, and then quickly cool it to 0°C; the amount of the initiator used is the same as that in S2; the total concentration of the reactants is set to 45wt% - 60wt%. S5: Drop the product solution obtained in S4 into diethyl ether with a volume eight times higher to precipitate a copolymer Poly (MMA - r - VPA - r - ADH - b - FTMAC) solid product. S6: Dissolve the solid product obtained in S5 in a mixed solvent of acetone / water, add gas - phase nanoparticles and stir to disperse, obtaining a coating suspension; the mass sum of the copolymer and gas - phase nanoparticles, and the amounts of acetone and water used are in the ratio of (1.05 - 1.45) g:(5 - 10) g:(0.5 - 1) g.

[0037] Thirdly, the present invention also provides an application of the superhydrophobic flame-retardant coating with high sunlight reflectivity in the field of building exterior wall coatings.

[0038] Preferably, the coating can be widely applied to the wooden peripheral structure of buildings, providing excellent sunlight reflection, superhydrophobicity and flame-retardant protection for it.

[0039] The present invention provides a superhydrophobic flame-retardant coating with high sunlight reflectivity, aiming to solve problems such as poor water resistance and unsatisfactory flame-retardant performance of existing organic high-reflection coatings. This coating has a high sunlight reflectivity, superhydrophobicity and excellent flame-retardant performance, and can be widely applied to multiple fields such as building wood and exterior wall coatings, with remarkable energy-saving, environmental protection and safety performances.

[0040] The production cost of the present invention is relatively low and the process is simple: Existing high-sunlight-reflection materials usually rely on multi-layer structures or metamaterial designs, which generally require precise physical / chemical vapor deposition techniques and complex micro / nano manufacturing techniques (such as electron beam lithography or nanoimprinting). These techniques are not only costly, but also have a complex production process and are difficult to achieve large-scale applications. In contrast, the present invention adopts a coating design with randomly distributed particles (specifically gas-phase nanoparticles, including silica, titanium dioxide, and aluminum oxide) combined with a porous structure. This randomly distributed structure does not require precise control of the arrangement positions of gas-phase nanoparticles, but is naturally dispersed on the polymer backbone through a spraying process and the solvent evaporation process to achieve enhanced light scattering, avoiding the dependence on high-precision techniques, greatly simplifying the preparation process, reducing the production cost, and having high potential for industrial application.

[0041] The present invention has high flame retardancy and environmental safety: Traditional high-sunlight-reflection polymer materials (such as PMMA, PTFE, and PVDF-HFP, etc.) have high flammability and will release toxic combustion products during the combustion process, which pose a serious threat to the environment and personnel safety, and their existing safety hazards are particularly prominent under high-temperature and drought use conditions. In contrast, the coating of the present invention adopts a formulation with excellent flame-retardant performance, which can reach the UL-94V-0 level, greatly improving the safety of the coating and preventing the spread of fire. In addition, by reasonably selecting raw materials and preparation processes, the stability of the coating under high-temperature environments has been significantly enhanced, and it has environmental adaptability and safety.

[0042] The present invention has excellent water resistance: The coating of the present invention not only has a high sunlight reflectivity, but also exhibits excellent superhydrophobic performance. The static contact angle of the coating reaches 151°, with excellent waterproofness, and can effectively avoid water penetration and adhesion. This characteristic enables the coating to maintain its high efficiency in complex external environments, especially in rainy or humid conditions.

[0043] The present invention has excellent energy-saving effects and is green and environmentally friendly: due to the high solar reflectivity of the coating (exceeding 95%), it can effectively reflect solar radiation, reduce the heat load inside the building, and thus reduce the energy consumption of air-conditioning and refrigeration systems. This not only significantly improves the energy utilization efficiency of the building, reduces carbon emissions, but also meets the requirements of today's green building materials and energy conservation and emission reduction, and has good environmental protection value.

[0044] In the present invention, the monomer raw materials of the copolymer include a bonding functional monomer, methyl methacrylate, vinyl phosphonic acid, 2-(perfluorohexyl)ethyl methacrylate, and are prepared by reversible addition-fragmentation chain transfer (RAFT) polymerization technology. Among them, the vinyl phosphonic acid used mainly plays a flame-retardant role, methyl methacrylate plays a film-forming role, the bonding functional monomer ensures the tight bonding between the coating and the substrate, and the terminal poly 2-(perfluorohexyl)ethyl methacrylate chain segment plays a role in enhancing the hydrophobicity of the coating due to self-enrichment on the air side during the drying process. The additionally added gas-phase nanoparticles play a role in enhancing reflection and synergistic flame retardancy. At the same time, the porous structure formed in the coating after water evaporation can effectively backscatter sunlight and improve the reflectivity.

[0045] Through the above design, the present invention comprehensively improves the multiple properties of the coating, which can not only significantly enhance the thermal management efficiency of the building facade and reduce air-conditioning energy consumption, but also provide long-term effective fire protection, superhydrophobicity and weather resistance protection for wood structures, and has broad application prospects and market value.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] (1) The present invention provides a superhydrophobic and flame-retardant coating with high solar reflectivity, which is obtained by mixing the copolymer Poly (MMA-r-VPA-r-ADH-b-FTMAC), gas-phase nanoparticles, acetone and water to obtain a coating suspension, and then spraying the coating suspension on the surface of the substrate and drying it. This coating has high solar reflectivity, superhydrophobicity and excellent flame-retardant properties.

[0048] (2) The copolymer Poly (MMA-r-VPA-r-ADH-b-FTMAC) in the present invention is prepared by RAFT polymerization technology from a bonding functional monomer, methyl methacrylate, vinyl phosphonic acid, 2-(perfluorohexyl)ethyl methacrylate. Among them, the vinyl phosphonic acid is used to improve the flame-retardant performance of the coating, methyl methacrylate plays a film-forming role, and the bonding functional monomer increases the adhesion between the substrate and the coating. 2-(perfluorohexyl)ethyl methacrylate is used to enhance the hydrophobicity of the coating, so that the present invention has good flame retardancy and hydrophobicity (the water contact angle can reach 150°).

[0049] (3) The present invention enhances the light reflection ability of the coating by incorporating gas-phase nanoparticles. In addition, the gas-phase nanoparticles can cooperate with the copolymer to further enhance the flame retardancy of the coating (which can reach the UL-94 V-0 level).

[0050] (4) The present invention uses a mixture of acetone and water as the solvent. During the drying process, the rapid evaporation of volatile acetone causes the copolymer to phase-separate from water. After the water evaporates, a porous structure (micropores) is formed in the coating. This porous structure can effectively backscatter sunlight and further enhance the reflectivity of the present invention (which can reach 95.1%).

[0051] (5) Due to its high solar reflectivity, superhydrophobicity, and excellent flame retardant properties, the present invention can be widely applied to the wooden exterior structures of buildings, improving environmental safety, energy-saving effects, and being green and environmentally friendly.

[0052] (6) The preparation method of the present invention is simple. The coating suspension is sprayed onto the substrate by a spraying process and then dried, avoiding the dependence on high-precision technologies, reducing production costs, and being widely applicable to industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 Gel Permeation Chromatography (GPC) test of the copolymer Poly (MMA-r-VPA-r-VA-b-FTMAC);

[0054] Figure 2 Fourier Transform Infrared Spectroscopy (FT-IR) test of the copolymer Poly (MMA-r-VPA-r-VA-b-FTMAC);

[0055] Figure 3 Standard FT-IR spectra of the homopolymers Poly VPA, Poly MMA, and Poly VA;

[0056] Figure 4 Phosphorus-31 Nuclear Magnetic Resonance Spectroscopy ( 31 31P NMR) test of the copolymer Poly (MMA-r-VPA-r-VA-b-FTMAC);

[0057] Figure 5 X-ray Photoelectron Spectroscopy (XPS) test of the copolymer Poly (MMA-r-VPA-r-VA-b-FTMAC);

[0058] Figure 6 Cross-sectional Scanning Electron Microscope (SEM) image of the coating prepared in Example 1;

[0059] Figure 7 Cross-sectional Scanning Electron Microscope (SEM) image of the coating prepared in Comparative Example 1;

[0060] Figure 8 Digital photos of Example 1 and Comparative Example 1 sprayed on the wood surface;

[0061] Figure 9 Reflectance spectra of Examples 1-6 and Comparative Example 1 in the ultraviolet-visible-near-infrared band. Detailed implementation mode

[0062] This embodiment is implemented on the premise of the technical solution of the present invention, and detailed implementation modes and specific operation processes are given, but the protection scope of the present invention is not limited to the following embodiments.

[0063] Unless otherwise specified, the reagents, methods, instruments and equipment used in the present invention are conventional reagents, methods, instruments and equipment in the art. Unless otherwise specified, the reagents and materials used in the following examples are all commercially available.

[0064] A superhydrophobic flame-retardant coating with high sunlight reflectance, the coating is obtained by spraying a coating suspension on the surface of a substrate and drying, and the coating suspension is obtained by mixing a copolymer, gas-phase nanoparticles, acetone and water. The thickness of the coating is not less than 50 μm, and the coating is a porous structure. The copolymer Poly (MMA-r-VPA-r-ADH-b-FTMAC) is prepared by reversible addition-fragmentation chain transfer (RAFT) polymerization technology from a bonding functional monomer, methyl methacrylate, vinylphosphonic acid, and 2-(perfluorohexyl)ethyl methacrylate. The bonding functional monomer includes any one of vinyl acetate, n-butyl methacrylate, and 2-ethylhexyl acrylate. The gas-phase nanoparticles include one or two of gas-phase silica, gas-phase titanium dioxide, and gas-phase aluminum oxide.

[0065] In the coating suspension, the mass ratio of the copolymer Poly (MMA-r-VPA-r-ADH-b-FTMAC) to the gas-phase nanoparticles is 1:(0.05-0.45), and the mass ratio of the total mass of the copolymer Poly (MMA-r-VPA-r-ADH-b-FTMAC) and the gas-phase nanoparticles to acetone and water is (1.05-1.45):(5-10):(0.5-1).

[0066] The preparation method of the above coating includes the following steps: S1: Prepare the copolymer Poly (MMA-r-VPA-r-ADH-b-FTMAC); S1.1: Mix the bonding functional monomer, methyl methacrylate, vinylphosphonic acid, a chain transfer reagent and acetone to obtain a mixed solution; S1.2: Add an initiator to the mixed solution, heat and stir the reaction under an inert gas atmosphere, and then perform a rapid cooling treatment to obtain a first product solution; S1.3: Drop the first product solution into diethyl ether to precipitate a solid intermediate product; S1.4: Dissolve the solid intermediate product in acetone, add 2-(perfluorohexyl)ethyl methacrylate and an initiator, heat and stir the reaction under an inert gas atmosphere, and then perform a rapid cooling treatment to obtain a second product solution; S1.5: Drop the second product solution into diethyl ether to precipitate the copolymer Poly (MMA-r-VPA-r-ADH-b-FTMAC); S2: Dissolve and disperse the copolymer Poly (MMA-r-VPA-r-ADH-b-FTMAC) and gas-phase nanoparticles in a mixed solvent of acetone and water to prepare a coating suspension; S3: Spray the coating suspension onto the surface of the substrate by a spraying process and dry it at room temperature to obtain the coating.

[0067] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0068] Example 1

[0069] 1) Add 10 g of methyl methacrylate, 3.78 g of vinylphosphonic acid, 2.86 g of vinyl acetate, 0.03 g of 2-[dodecylthio(thiocarbonyl)thio]-2-methylpropanoic acid, 0.006 g of azobisisobutyronitrile and 16 g of acetone to a 250 mL eggplant-shaped reaction flask. Gradually heat to 70 °C under a nitrogen atmosphere and continue the reaction for 24 h. Then quickly cool the reaction solution to 0 °C and drop it into 350 mL of diethyl ether to collect a white solid intermediate product.

[0070] 2) Dissolve the intermediate product from step 1, 0.006 g of azobisisobutyronitrile and 4.16 g of 2-(perfluorohexyl)ethyl methacrylate in 16 g of acetone. Gradually heat to 70 °C under a nitrogen atmosphere and continue the reaction for 12 h. Then quickly cool the reaction solution to 0 °C and drop it into 350 mL of diethyl ether to collect a white solid copolymer product Poly (MMA-r-VPA-r-VA-b-FTMAC).

[0071] 3) Take 1 g of Poly (MMA-r-VPA-r-VA-b-FTMAC) and dissolve it in a mixed solvent of acetone / water (8 g / 0.5 g). Then add 0.15 g of gas-phase aluminum oxide and stir to disperse to obtain a suspension coating.

[0072] Example 2

[0073] 1) 10 g of methyl methacrylate, 3.78 g of vinylphosphonic acid, 2.86 g of vinyl acetate, 0.03 g of 2-[dodecylthio(thiocarbonyl)thio]-2-methylpropanoic acid, 0.006 g of azobisisobutyronitrile and 16 g of acetone were added to a 250 mL eggplant-shaped reaction flask. The temperature was gradually raised to 70 °C under a nitrogen atmosphere and the reaction was continued for 24 h. Subsequently, the reaction solution was rapidly cooled to 0 °C and dropped into 350 mL of diethyl ether to collect a white solid intermediate product.

[0074] 2) The intermediate product from step 1, 0.006 g of azobisisobutyronitrile and 4.16 g of 2-(perfluorohexyl)ethyl methacrylate were dissolved in 16 g of acetone. The temperature was gradually raised to 70 °C under a nitrogen atmosphere and the reaction was continued for 12 h. Subsequently, the reaction solution was rapidly cooled to 0 °C and dropped into 350 mL of diethyl ether to collect a white solid copolymer product Poly (MMA-r-VPA-r-VA-b-FTMAC).

[0075] 3) 1 g of Poly (MMA-r-VPA-r-VA-b-FTMAC) was dissolved in a mixed solvent of acetone / water (8 g / 0.5 g), and then 0.15 g of fumed titanium dioxide was added and stirred to disperse to obtain a suspension coating.

[0076] Example 3

[0077] 1) 10 g of methyl methacrylate, 3.78 g of vinylphosphonic acid, 2.86 g of vinyl acetate, 0.03 g of 2-[dodecylthio(thiocarbonyl)thio]-2-methylpropanoic acid, 0.006 g of azobisisobutyronitrile and 16 g of acetone were added to a 250 mL eggplant-shaped reaction flask. The temperature was gradually raised to 70 °C under a nitrogen atmosphere and the reaction was continued for 24 h. Subsequently, the reaction solution was rapidly cooled to 0 °C and dropped into 350 mL of diethyl ether to collect a white solid intermediate product.

[0078] 2) The intermediate product from step 1, 0.006 g of azobisisobutyronitrile and 4.16 g of 2-(perfluorohexyl)ethyl methacrylate were dissolved in 16 g of acetone. The temperature was gradually raised to 70 °C under a nitrogen atmosphere and the reaction was continued for 12 h. Subsequently, the reaction solution was rapidly cooled to 0 °C and dropped into 350 mL of diethyl ether to collect a white solid copolymer product Poly (MMA-r-VPA-r-VA-b-FTMAC).

[0079] 3) 1 g of Poly (MMA-r-VPA-r-VA-b-FTMAC) was dissolved in a mixed solvent of acetone / water (8 g / 0.5 g), and then 0.075 g of fumed silica and 0.075 g of fumed alumina were added and stirred to disperse to obtain a suspension coating.

[0080] Example 4

[0081] 1) 10 g of methyl methacrylate, 3.78 g of vinylphosphonic acid, 2.86 g of vinyl acetate, 0.03 g of 2-[dodecylthio(thiocarbonyl)thio]-2-methylpropanoic acid, 0.006 g of azobisisobutyronitrile and 16 g of acetone were added to a 250 mL eggplant-shaped reaction flask. The temperature was gradually raised to 70 °C under a nitrogen atmosphere and the reaction was continued for 24 h. Subsequently, the reaction solution was rapidly cooled to 0 °C and dropped into 350 mL of diethyl ether to collect a white solid intermediate product.

[0082] 2) The intermediate product from step 1, 0.006 g of azobisisobutyronitrile and 4.16 g of 2-(perfluorohexyl)ethyl methacrylate were dissolved in 16 g of acetone. The temperature was gradually raised to 70 °C under a nitrogen atmosphere and the reaction was continued for 12 h. Subsequently, the reaction solution was rapidly cooled to 0 °C and dropped into 350 mL of diethyl ether to collect a white solid copolymer product Poly (MMA-r-VPA-r-VA-b-FTMAC).

[0083] 3) 1 g of Poly (MMA-r-VPA-r-VA-b-FTMAC) was dissolved in a mixed solvent of acetone / water (8 g / 0.5 g). Subsequently, 0.075 g of fumed titanium dioxide and 0.075 g of fumed aluminum oxide were added and stirred to disperse to obtain a suspension coating.

[0084] Example 5

[0085] 1) 10 g of methyl methacrylate, 3.78 g of vinylphosphonic acid, 4.25 g of n-butyl methacrylate, 0.03 g of 2-[dodecylthio(thiocarbonyl)thio]-2-methylpropanoic acid, 0.006 g of azobisisobutyronitrile and 16 g of acetone were added to a 250 mL eggplant-shaped reaction flask. The temperature was gradually raised to 70 °C under a nitrogen atmosphere and the reaction was continued for 24 h. Subsequently, the reaction solution was rapidly cooled to 0 °C and dropped into 350 mL of diethyl ether to collect a white solid intermediate product.

[0086] 2) The intermediate product from step 1, 0.006 g of azobisisobutyronitrile and 4.16 g of 2-(perfluorohexyl)ethyl methacrylate were dissolved in 16 g of acetone. The temperature was gradually raised to 70 °C under a nitrogen atmosphere and the reaction was continued for 12 h. Subsequently, the reaction solution was rapidly cooled to 0 °C and dropped into 350 mL of diethyl ether to collect a white solid copolymer product Poly(MMA-r-VPA-r-BA-b-FTMAC).

[0087] 3) 1 g of Poly(MMA-r-VPA-r-BA-b-FTMAC) was dissolved in a mixed solvent of acetone / water (8 g / 0.5 g). Subsequently, 0.15 g of fumed titanium dioxide was added and stirred to disperse to obtain a suspension coating.

[0088] Example 6

[0089] 1) Add 10 g of methyl methacrylate, 3.78 g of vinylphosphonic acid, 6.12 g of 2-ethylhexyl acrylate, 0.03 g of 2-[dodecylthio(thiocarbonyl)thio]-2-methylpropanoic acid, 0.006 g of azobisisobutyronitrile and 18 g of acetone into a 250 mL eggplant-shaped reaction flask. Gradually heat up to 70 °C under a nitrogen atmosphere and continue the reaction for 24 h. Then quickly cool the reaction solution to 0 °C and drop it into 350 mL of diethyl ether to collect a white solid intermediate product.

[0090] 2) Dissolve the intermediate product from step 1, 0.006 g of azobisisobutyronitrile and 4.16 g of 2-(perfluorohexyl)ethyl methacrylate in 18 g of acetone. Gradually heat up to 70 °C under a nitrogen atmosphere and continue the reaction for 12 h. Then quickly cool the reaction solution to 0 °C and drop it into 350 mL of diethyl ether to collect a white solid copolymer product Poly(MMA-r-VPA-r-EA-b-FTMAC).

[0091] 3) Dissolve 1 g of Poly(MMA-r-VPA-r-EA-b-FTMAC) in a mixed solvent of acetone / water (8 g / 0.5 g), and then add 0.05 g of fumed titanium dioxide and stir to disperse to obtain a suspension coating.

[0092] Comparative Example 1

[0093] 1) Add 10 g of methyl methacrylate, 3.78 g of vinylphosphonic acid, 2.86 g of vinyl acetate, 0.03 g of 2-[dodecylthio(thiocarbonyl)thio]-2-methylpropanoic acid, 0.006 g of azobisisobutyronitrile and 16 g of acetone into a 250 mL eggplant-shaped reaction flask. Gradually heat up to 70 °C under a nitrogen atmosphere and continue the reaction for 24 h. Then quickly cool the reaction solution to 0 °C and drop it into 350 mL of diethyl ether to collect a white solid intermediate product.

[0094] 2) Dissolve the intermediate product from step 1, 0.006 g of azobisisobutyronitrile and 4.16 g of 2-(perfluorohexyl)ethyl methacrylate in 16 g of acetone. Gradually heat up to 70 °C under a nitrogen atmosphere and continue the reaction for 12 h. Then quickly cool the reaction solution to 0 °C and drop it into 350 mL of diethyl ether to collect a white solid copolymer product Poly(MMA-r-VPA-r-VA-b-FTMAC).

[0095] 3) Dissolve 1 g of Poly(MMA-r-VPA-r-VA-b-FTMAC) in a mixed solvent of acetone / water (8 g / 0.5 g) to obtain a solution coating.

[0096] Comparative Example 2

[0097] 1) Add 10 g of methyl methacrylate, 3.78 g of vinylphosphonic acid, 2.86 g of vinyl acetate, 0.03 g of 2 - [dodecylthio(thiocarbonyl)thio]-2-methylpropanoic acid, 0.006 g of azobisisobutyronitrile and 16 g of acetone into a 250 mL eggplant-shaped reaction flask. Gradually heat up to 70 °C under a nitrogen atmosphere and continue the reaction for 24 h. Subsequently, quickly cool the reaction solution to 0 °C and drop it into 350 mL of diethyl ether to collect a white solid intermediate product.

[0098] 2) Dissolve the intermediate product from step 1, 0.006 g of azobisisobutyronitrile and 4.16 g of 2-(perfluorohexyl)ethyl methacrylate in 16 g of acetone. Gradually heat up to 70 °C under a nitrogen atmosphere and continue the reaction for 12 h. Subsequently, quickly cool the reaction solution to 0 °C and drop it into 350 mL of diethyl ether to collect a white solid copolymer product Poly(MMA-r-VPA-r-VA-b-FTMAC).

[0099] 3) Dissolve 1 g of Poly(MMA-r-VPA-r-VA-b-FTMAC) in 8.5 g of acetone solvent to obtain a solution coating.

[0100] Spray the coatings obtained in Examples 1 - 6 and Comparative Examples 1 - 2 on the surface of Chinese fir boards and air-dry at room temperature for 6 h to obtain Chinese fir boards covered with coatings. Spray the coating in an aluminum foil petri dish and after air-drying at room temperature for 6 h, it can be peeled off to obtain a self-supporting coating.

[0101] Figures 1 - 5 For the structural characterization of the copolymer product Poly (MMA-r-VPA-r-VA-b-FTMAC), it is proved that the monomers are successfully polymerized to obtain the copolymer.

[0102] Figure 1 The GPC test results of Poly (MMA-r-VPA-r-VA-b-FTMAC) are shown. A single chromatographic peak appears within the retention time range of 6.8 min to 9.9 min, and its number-average molecular weight (Mn) is 30278 g / mol, confirming the successful synthesis of a target single polymer with a uniform molecular weight distribution.

[0103] Figure 2 This is the FT-IR spectrum of Poly (MMA-r-VPA-r-VA-b-FTMAC). The positions of each characteristic peak are consistent with the standard peak positions of the homopolymers of the corresponding monomers (methyl methacrylate (MMA), vinyl phosphoric acid (VPA), vinyl acetate (VA)) ( Figure 3 )

[0104] Figure 4 1H NMR spectrum of the polymer Poly (MMA-r-VPA-r-VA-b-FTMAC), the main peak chemical shift appears at about 31 ppm, which is consistent with the characteristic signal of the phosphorus atom in the phosphate group O=P(OH)2. The singularity of this peak position indicates the presence of the polyvinyl phosphoric acid chain segment in the copolymer, and no obvious interference peaks of free phosphate or hydrolysis by-products are detected, further confirming the structural integrity of the target copolymer. 31 The XPS test results of 31 show multiple characteristic binding energy peaks. P2p (about 131 eV), P2s (about 189 eV), corresponding to the characteristic binding energy of the phosphorus atom in the O=P(OH)2 group, indicating the presence of the polyvinyl phosphoric acid chain segment in the copolymer. C1s (about 285 eV) belongs to the contribution of carbon-carbon / carbon-hydrogen bonds (C-C / C-H) in the main chain and side chains, and at the same time contains a small amount of the carbon environment of the ester group (C=O). O1s (about 532 eV) comes from the oxygen atoms in the ester group (C=O) and the phosphate group (P-O). F1s (about 689 eV) corresponds to the characteristic peak of the fluorine atom in the perfluorohexyl chain segment, proving the successful introduction of the fluorinated hydrophobic chain segment.

[0105] Figure 5 The SEM images of and

[0105] after air drying for Example 1 and Comparative Example 1 respectively. The rapid evaporation of volatile acetone causes the phase separation of Poly (MMA-r-VPA-r-VA-b-FTMAC) in Comparative Example 1 from the aqueous phase. The micropores formed in the coating after water evaporation (

[0106] Figure 6 the place marked by the yellow dotted line in Figure 7 Figure 7 ) can effectively backscatter sunlight. Therefore, the coating visually presents white ( Figure 6 Figure 6 ). This structural property endows the coating with excellent daylight reflection ability. On this basis, the coating design combining randomly distributed gas-phase aluminum oxide particles with the porous polymer structure in Example 1 can achieve more significant enhancement of light scattering, and can more effectively reduce the heat accumulation on the wood surface. Especially under hot climate conditions, it makes a significant contribution to the energy conservation of buildings. Figure 8 Figure 8 ) This structural property endows the coating with excellent daylight reflection ability. On this basis, the coating design combining randomly distributed gas-phase aluminum oxide particles with the porous polymer structure in Example 1 can achieve more significant enhancement of light scattering, and can more effectively reduce the heat accumulation on the wood surface. Especially under hot climate conditions, it makes a significant contribution to the energy conservation of buildings.

[0107] Figure 9 Figure 9 shows the reflectance data of Examples 1-6 and Comparative Example 1 in the ultraviolet-visible-near-infrared band (measured by a UV-VIS-NIR spectrophotometer). It can be seen that the reflectance of the coating with added gas-phase nanoparticles is significantly improved compared with Comparative Example 1. This means that the wooden exterior wall of a building using the coating of the present invention can effectively avoid heat accumulation under strong sunlight irradiation, further improving the building energy efficiency.

[0108] Table 1 List of performance parameters of Examples 1-6 and Comparative Example 1

[0109]

[0110] Table 1 is a table of performance parameters for Examples 1 to 6 and Comparative Examples 1-2. It can be seen from Table 1 that the coating prepared by the present invention has a high solar reflectance and can also meet the UL-94 V-0 level flame retardancy standard, demonstrating its excellent flame retardant performance. Compared with the existing coatings for wood substrates, the coating of the present invention has a significant improvement in fire safety, can effectively reduce the fire hazard, and provide higher safety protection. In addition, the coatings in Examples 1 to 6 exhibit excellent superhydrophobicity, and the water contact angles can all reach 150°. This is mainly attributed to the self-enrichment of the poly(2-(perfluorohexyl)ethyl methacrylate) chain segments on the air side during the drying process, which enhances the hydrophobicity of the coating surface.

[0111] In summary, the present invention provides a superhydrophobic flame retardant coating with high solar reflectance. This coating has a high solar reflectance, superhydrophobicity, and excellent flame retardant performance, and can be widely applied to various fields such as building wood and exterior wall coatings, with significant energy-saving, environmental protection, and safety performance.

[0112] The above description of the embodiments is for the convenience of those of ordinary skill in the art to understand and use the invention. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative labor. Therefore, the present invention is not limited to the above embodiments, and the improvements and modifications made by those skilled in the art without departing from the scope of the present invention should be within the protection scope of the present invention.

Claims

1. A superhydrophobic flame-retardant coating with high sunlight reflectivity, characterized in that, The raw materials of the coating include the following components: copolymer Poly (MMA-r-VPA-r-ADH-b-FTMAC), gas-phase nanoparticles, acetone and water. The structural formula of the copolymer Poly (MMA-r-VPA-r-ADH-b-FTMAC) is as follows: ； Among them, ADH is a bonding functional monomer, including any one of vinyl acetate, n-butyl methacrylate, and 2-ethylhexyl acrylate. The value ranges of x, y, z, and k are respectively: 70 < x < 250, 35 < y < 100, 25 < z < 100, 10 < k < 100.

2. The superhydrophobic flame-retardant coating with high sunlight reflectivity according to claim 1, characterized in that, The copolymer Poly (MMA-r-VPA-r-ADH-b-FTMAC) is prepared by reversible addition-fragmentation chain transfer polymerization technology from a bonding functional monomer, methyl methacrylate, vinylphosphonic acid, and 2-(perfluorohexyl)ethyl methacrylate.

3. A superhydrophobic flame-retardant coating with high sunlight reflectivity according to claim 1, characterized in that The molar parts of each monomer raw material of the copolymer Poly (MMA-r-VPA-r-ADH-b-FTMAC) are as follows: Bonding functional monomer 15-20 parts; Methyl methacrylate 40-60 parts; Vinylphosphonic acid 15-25 parts; 2-(Perfluorohexyl)ethyl methacrylate 3-25 parts.

4. The superhydrophobic flame retardant coating with high sunlight reflectivity according to claim 1, characterized in that, The gas-phase nanoparticles include one or two of gas-phase silica, gas-phase titanium dioxide, and gas-phase aluminum oxide. The mass ratio of the copolymer Poly (MMA-r-VPA-r-ADH-b-FTMAC) to the gas-phase nanoparticles is 1:0.05-0.

45. The mass sum of the copolymer Poly (MMA-r-VPA-r-ADH-b-FTMAC) and the gas-phase nanoparticles to acetone and water is 1.05-1.45:5-10:0.5-1.

5. A superhydrophobic and flame-retardant coating with high sunlight reflectivity according to claim 1, characterized in that, The thickness of the coating is not less than 50 μm. The coating is a porous structure with a porosity of 30% - 70% and a specific surface area of 50 - 200 m 2 / g, and the pore size is 0.5 - 5 μm.

6. A method for preparing a superhydrophobic flame-retardant coating with high sunlight reflectivity according to any one of claims 1-5, characterized in that, It includes the following steps: S1: Prepare the copolymer Poly (MMA-r-VPA-r-ADH-b-FTMAC); S2: Dissolve and disperse the copolymer Poly (MMA-r-VPA-r-ADH-b-FTMAC) and gas-phase nanoparticles in a mixed solvent of acetone and water to prepare a coating suspension; S3: Spray the coating suspension on the surface of the substrate by a spraying process and dry it at room temperature to obtain the coating.

7. The preparation method of a superhydrophobic flame-retardant coating with high sunlight reflectivity according to claim 6, characterized in that, Step S1 specifically includes the following steps: S1.1: Mix the bonding functional monomer, methyl methacrylate, vinylphosphonic acid, chain transfer reagent with acetone to obtain a mixed solution; S1.2: Add an initiator to the mixed solution, heat and stir the reaction under an inert gas atmosphere, and then perform a rapid cooling treatment to obtain a first product solution; S1.3: Drop the first product solution into ether to precipitate a solid intermediate product; S1.4: Dissolve the solid intermediate product in acetone, add 2-(perfluorohexyl)ethyl methacrylate and an initiator, heat and stir the reaction under an inert gas atmosphere, and then perform a rapid cooling treatment to obtain a second product solution. S1.5: Drop the second product solution into diethyl ether to precipitate the copolymer Poly (MMA-r-VPA-r-ADH-b-FTMAC).

8. The preparation method of a highly sunlight-reflective superhydrophobic flame-retardant coating according to claim 7, characterized in that In step S1.1, the dosage of the chain transfer reagent is 0.02% - 0.1% of the total molar amount of the bonding functional monomer, methyl methacrylate, and vinylphosphonic acid; the total concentration of the bonding functional monomer, methyl methacrylate, and vinylphosphonic acid in the mixed solution is set to 45wt% - 60wt%; the chain transfer reagent includes 2-[dodecylthio(thiocarbonyl)thio]-2-methylpropanoic acid; In step S1.2, the initiator includes azobisisobutyronitrile, the inert gas includes nitrogen, the heating temperature is 60 - 80 °C, the stirring speed is 500 - 1000 rpm, the time is 12 - 24 h, the temperature of the quenching treatment is -4 - 5 °C, and the dosage of the initiator is 5 - 50% of the molar amount of the chain transfer reagent in step S1.1; In step S1.3, the volume ratio of diethyl ether to the first product solution is 8:1 - 20:1; In step S1.4, the sum of the masses of the solid intermediate product and 2-(perfluorohexyl)ethyl methacrylate accounts for 45 - 60% of the sum of the masses of the solid intermediate product, 2-(perfluorohexyl)ethyl methacrylate, and acetone. The inert gas includes nitrogen, the heating temperature is 60 - 80 °C, the stirring speed is 500 - 1000 rpm, the time is 8 - 16 h, the temperature of the quenching treatment is -4 - 5 °C, and the dosage of the initiator is 5 - 50% of the molar amount of the chain transfer reagent in step S1.

1. The initiator includes azobisisobutyronitrile; In step S1.5, the volume ratio of diethyl ether to the second product solution is 8:1 - 20:

1.

9. The preparation method of a highly sunlight-reflective superhydrophobic flame-retardant coating according to claim 6, characterized in that In step S3, the substrate includes building wood, and the parameters of the spraying process are: spray gun pressure 0.3 - 0.6 MPa, spraying distance 100 - 300 mm, spray gun moving speed 0.05 - 0.5 m / s, and the room temperature drying time is 4 - 8 h.

10. Application of a highly sunlight-reflective superhydrophobic flame-retardant coating according to any one of claims 1 - 5 in the field of building exterior wall coatings.

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