A super-hydrophobic flame-retardant coating with high sunlight reflection and its preparation method and application

Abstract

The present invention relates to a highly solar-reflective super-hydrophobic flame-retardant coating and its preparation method and application. The coating is first prepared by mixing a copolymer Poly(MMA-r-VPA-r-ADH-b-FTMAC), gas-phase nanoparticles, acetone, and water to obtain a coating suspension. The coating suspension is then sprayed onto a substrate and dried at room temperature. The rapid evaporation of volatile acetone induces phase separation between the polymer and water, forming a porous, highly solar-reflective coating after drying. The copolymer Poly(MMA-r-VPA-r-ADH-b-FTMAC) is prepared from a bonding functional monomer, methyl methacrylate, vinylphosphonic acid, and 2-(perfluorohexyl)ethyl methacrylate via reversible addition-fragmentation chain transfer (RAFT) polymerization. Compared with the prior art, the reflectivity of the present invention can reach 95%. The resulting coating has excellent super-hydrophobicity, a static contact angle of 151°, and exhibits excellent flame retardancy, capable of achieving a UL-94 V-0 rating.

Description

Technical Field

[0001] The present invention relates to the technical field of coatings, and in particular to a super-hydrophobic flame-retardant coating with high sunlight reflection, and a preparation method and application thereof. Background Art

[0002] With the increasingly severe global energy crisis and climate change issues, energy conservation and environmental protection have become important development directions for the construction industry. In this context, the energy efficiency and safety of building materials have received widespread attention. As a commonly used building material, wood has good natural beauty and excellent structural strength, but its flammability and poor thermal insulation properties limit its widespread application in scenes such as building facades. Especially in the external coating treatment of wood structures, traditional coatings mostly focus on flame retardancy as the main function, lack comprehensive consideration of sunlight reflection, thermal management and long-term weather resistance, and are difficult to meet the multifunctional requirements of modern buildings for coating materials. In building exterior wall coating technology, high solar reflective coatings can effectively reduce the air conditioning energy consumption of buildings, especially in hot climates, and improve the energy efficiency performance of buildings. However, most existing high-reflective coatings only focus on reflective ability, and lack consideration of hydrophobicity and fire resistance.

[0003] CN114752236A discloses a method for preparing a highly reflective, wear-resistant, super-hydrophobic coating by surface-modifying GCC microparticles and TiO2 nanoparticles with room-temperature vulcanized silicone rubber (RTV) and tetraethyl orthosilicate (TEOS). This coating, applied to cement surfaces via a spraying process, effectively improves reflectivity and wear resistance. However, insufficient attention has been paid to the coating's flame retardancy, which may not effectively reduce the spread of fire in the event of a fire, posing a public safety hazard. CN116218364A discloses a near-infrared highly reflective radiative cooling coating and its preparation method. This coating utilizes n-hexane as a solvent, PDMS as a film-forming material, and TiO2 and Y2O3 as fillers. It effectively reflects solar radiation, achieving a radiative cooling effect. However, while this type of coating performs well in terms of solar reflection, its primary component, PDMS, has relatively low flame retardancy.

[0004] Therefore, developing a coating material that combines high sunlight reflectivity, super-hydrophobicity, and flame retardant properties can not only effectively improve the energy efficiency of buildings, but also enhance the safety and durability of wood, which has become a technical problem that needs to be solved urgently. Summary of the Invention

[0005] The purpose of the present invention is to provide a super hydrophobic flame retardant coating with high solar reflectivity and a preparation method and application thereof, wherein the coating has high solar reflectivity, super hydrophobicity and excellent flame retardant properties.

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

[0007] In one aspect, the present invention provides a highly solar-reflective, super-hydrophobic, flame-retardant coating. The raw materials of the coating include the following components: a copolymer Poly (MMA-r-VPA-r-ADH-b-FTMAC), gas-phase nanoparticles, acetone, and water. The copolymer Poly (MMA-r-VPA-r-ADH-b-FTMAC) has the following structural formula:

[0008] ;

[0009] Wherein, ADH is a bonding functional monomer, including any one of vinyl acetate, n-butyl methacrylate, and 2-ethylhexyl acrylate, and the value ranges of x, y, z, and k are: 70 <x<250、35<y<100、25<z<100、10<k<100。

[0010] Preferably, in the structural formula, r and b represent that the monomers on the right side are introduced through random copolymerization (r) or block copolymerization (b).

[0011] Preferably, the copolymer Poly (MMA-r-VPA-r-ADH-b-FTMAC) is prepared from a bonding functional monomer (ADH), methyl methacrylate (MMA), vinylphosphonic acid (VPA), and 2-(perfluorohexyl)ethyl methacrylate (FTMAC) by reversible addition-fragmentation chain transfer polymerization (RAFT) technology.

[0012] Preferably, the molar fractions of the monomeric raw materials of the copolymer Poly (MMA-r-VPA-r-ADH-b-FTMAC) are as follows:

[0013] 15-20 parts of bonding functional monomer;

[0014] 40-60 parts of methyl methacrylate;

[0015] 15-25 parts of vinylphosphonic acid;

[0016] 3-25 parts of 2-(perfluorohexyl)ethyl methacrylate

[0017] Preferably, the gas-phase nanoparticles include one or two of gas-phase silicon dioxide, gas-phase titanium dioxide, and gas-phase aluminum oxide.

[0018] Preferably, the mass ratio of the copolymer Poly (MMA-r-VPA-r-ADH-b-FTMAC) and the gas-phase nanoparticles is 1:(0.05-0.45).

[0019] Preferably, the mass ratio of the sum of the 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).

[0020] Preferably, the thickness of the coating is not less than 50 μm, the coating is a porous structure, the porosity is 30% to 70%, and the specific surface area is 50 to 200 m 2 / g, pore size is 0.5~5 μm.

[0021] In a second aspect, the present invention provides a method for preparing the highly solar-reflective super-hydrophobic flame-retardant coating, comprising the following steps:

[0022] S1: Preparation of copolymer Poly (MMA-r-VPA-r-ADH-b-FTMAC);

[0023] S2: dissolving and dispersing 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;

[0024] S3: spraying the coating suspension onto the surface of the substrate through a spraying process, and drying at room temperature to obtain the coating.

[0025] Preferably, step S1 specifically includes the following steps:

[0026] S1.1: Mix the adhesive functional monomer, methyl methacrylate, vinylphosphonic acid, chain transfer agent, and acetone to obtain a mixed solution;

[0027] S1.2: Add an initiator to the mixed solution, heat and stir under an inert gas atmosphere to react, and then quench to obtain a first product solution;

[0028] S1.3: Add the first product solution dropwise into diethyl ether to precipitate a solid intermediate product;

[0029] S1.4: Dissolve the solid intermediate product in acetone, add 2-(perfluorohexyl)ethyl methacrylate and an initiator, heat and stir under an inert atmosphere, and then quench to obtain a second product solution.

[0030] S1.5: The second product solution was dropped into diethyl ether to precipitate and obtain the copolymer Poly (MMA-r-VPA-r-ADH-b-FTMAC).

[0031] Preferably, in step S1.1, the amount of the chain transfer agent used is 0.02% to 0.1% of the total molar amount of the adhesive functional monomer, methyl methacrylate, and vinylphosphonic acid.

[0032] 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 45 wt % to 60 wt %.

[0033] Preferably, in step S1.1, the chain transfer reagent includes 2-[dodecylthio(thiocarbonyl)thio]-2-methylpropionic acid.

[0034] Preferably, in step S1.2, the initiator includes azobisisobutyronitrile.

[0035] 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.

[0036] Preferably, in step S1.2, the temperature of the quenching treatment is -4-5°C, more preferably 0°C.

[0037] Preferably, in step S1.2, the amount of the initiator used is 5-50% of the molar amount of the chain transfer reagent in step S1.1.

[0038] Preferably, in step S1.3, the volume ratio of the diethyl ether to the first product solution is greater than 8, more preferably 8:1 to 20:1.

[0039] 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.

[0040] Further preferably, in step S1.4, the mass of the 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.

[0041] Preferably, in step S1.4, the inert gas includes nitrogen, the heating temperature is 60-80°C, the stirring speed is 500-1000 rpm, and the time is 8-16 h, more preferably 12 h.

[0042] Preferably, in step S1.4, the temperature of the quenching treatment is -4-5°C, more preferably 0°C.

[0043] Preferably, in step S1.4, the amount of the initiator used is 5-50% of the molar amount of the chain transfer reagent in step S1.1.

[0044] Preferably, in step S1.4, the initiator includes azobisisobutyronitrile.

[0045] Preferably, in step S1.5, the volume ratio of the diethyl ether to the second product solution is greater than 8, more preferably 8:1 to 20:1.

[0046] Preferably, in step S3, the substrate comprises construction timber.

[0047] Preferably, in step S3, the parameters of the spraying process are: spray gun pressure 0.3-0.6 MPa, spraying distance 100-300 mm, and spray gun moving speed 0.05-0.5 m / s.

[0048] Preferably, in step S3, the drying time at room temperature is 4-8 h, more preferably 6 h.

[0049] In the present invention, during the drying process at room temperature, the rapid evaporation of the volatile acetone in the mixed solvent promotes phase separation between the copolymer and water, and a porous coating is formed after the water is completely evaporated.

[0050] Preferably, the method for preparing the highly solar reflective super-hydrophobic flame-retardant coating comprises the following steps:

[0051] S1: Mixing a bonding functional monomer, methyl methacrylate, vinyl phosphonic acid, and a chain transfer agent 2-[dodecylthio(thiocarbonyl)thio]-2-methylpropionic acid with an acetone solvent; wherein the amount of the chain transfer agent 2-[dodecylthio(thiocarbonyl)thio]-2-methylpropionic acid is 0.02% to 0.1% of the total molar amount of the bonding functional monomer, methyl methacrylate, and vinyl phosphonic acid; and the total concentration of the bonding functional monomer, methyl methacrylate, and vinyl phosphonic acid monomer in the mixed solution is set to 45wt% to 60wt%;

[0052] S2: Add initiator azobisisobutyronitrile to the mixed solution of S1, heat to 60-80°C under nitrogen atmosphere, stir for 12-24 hours, and then cool to 0°C. The amount of initiator azobisisobutyronitrile is 5-50% of the molar amount of chain transfer reagent in S1.

[0053] S3: The product solution obtained in S2 is added dropwise into 8 times the volume of diethyl ether to precipitate a solid intermediate product;

[0054] S4: The intermediate product obtained in S3 was dissolved in acetone solvent again, and the monomer 2-(perfluorohexyl)ethyl methacrylate and the initiator azobisisobutyronitrile were added. The temperature was raised to 60-80°C under a nitrogen atmosphere, and the mixture was stirred for reaction for 12 hours, and then suddenly cooled to 0°C. The amount of the initiator used was the same as that in S2. The total concentration of the reactants was set to 45wt%-60wt%.

[0055] S5: The product solution obtained in S4 was added dropwise into 8 times the volume of diethyl ether to precipitate a copolymer Poly (MMA-r-VPA-r-ADH-b-FTMAC) solid product;

[0056] S6: The solid product obtained in S5 is dissolved in a mixed solvent of acetone / water, and the gas-phase nanoparticles are added and stirred to disperse to obtain a coating suspension; the mass ratio of the copolymer and the gas-phase nanoparticles and the amount of acetone and water is (1.05~1.45) g: (5~10) g: (0.5~1) g.

[0057] In a third aspect, the present invention also provides an application of the highly solar-reflective super-hydrophobic flame-retardant coating in the field of building facade coatings.

[0058] Preferably, the coating can be widely used in wooden exterior structures of buildings to provide them with excellent sunlight reflection, super hydrophobicity and flame retardant protection.

[0059] This invention provides a highly solar-reflective, super-hydrophobic, flame-retardant coating designed to address the problems of existing organic highly reflective coatings, such as poor water resistance and flame retardancy. This coating, with its high solar reflectivity, super-hydrophobicity, and excellent flame retardancy, can be widely used in a variety of applications, including building timber and exterior wall coatings, offering significant energy-saving, environmental, and safety benefits.

[0060] The present invention offers low production costs and a simple process. Existing high-solar-reflective materials typically rely on multilayer structures or metamaterial designs, which require precise physical / chemical vapor deposition techniques and complex micro / nanofabrication technologies (such as electron beam lithography or nanoimprinting). These technologies are not only costly but also complex, making large-scale application difficult. The present invention, however, utilizes a coating design with randomly distributed particles (specifically, vapor-phase nanoparticles, including silica, titania, and alumina) combined with a porous structure. This random distribution eliminates the need for precise control of the arrangement of the vapor-phase nanoparticles. Instead, the particles are naturally dispersed on the polymer backbone during spraying and solvent evaporation to enhance light scattering. This eliminates the need for high-precision technology, greatly simplifies the preparation process, reduces production costs, and has high potential for industrial application.

[0061] The present invention has high flame retardancy and environmental safety: Traditional high-solar reflective polymer materials (such as PMMA, PTFE, and PVDF-HFP) are highly flammable and release toxic combustion products during combustion, which pose a serious threat to the environment and personnel safety. The potential safety hazards are particularly prominent under high-temperature and arid conditions. In contrast, the coating of the present invention uses a formula with excellent flame retardant properties and can achieve the UL-94V-0 level, greatly improving the safety of the coating and preventing the spread of fire. In addition, through the rational selection of raw materials and preparation processes, the present invention significantly enhances the stability of the coating in high-temperature environments, and possesses environmental adaptability and safety.

[0062] The present invention exhibits excellent water resistance: The coating not only has high solar reflectivity but also exhibits excellent superhydrophobic properties. The static contact angle of the coating reaches 151°, providing excellent water resistance and effectively preventing water penetration and adhesion. This property enables the coating to maintain its high functionality even in complex external environments, especially rainy or humid conditions.

[0063] This invention offers excellent energy-saving benefits and is environmentally friendly: Due to the coating's high solar reflectance (over 95%), it effectively reflects solar radiation, reducing the heat load inside buildings and, consequently, lowering energy consumption for air conditioning and refrigeration systems. This significantly improves a building's energy efficiency and reduces carbon emissions, while also meeting current requirements for green building materials and energy conservation and emission reduction, demonstrating excellent environmental value.

[0064] In the present invention, the monomer raw materials of the copolymer include a bonding functional monomer, methyl methacrylate, vinyl phosphonic acid, and 2-(perfluorohexyl) ethyl methacrylate, and are prepared by reversible addition-fragmentation chain transfer (RAFT) polymerization technology. The vinyl phosphonic acid used mainly plays a flame retardant role, methyl methacrylate plays a film-forming role, the bonding functional monomer ensures the close bonding of the coating and the substrate, and the terminal poly 2-(perfluorohexyl) ethyl methacrylate 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 reflectivity.

[0065] The present invention comprehensively improves the multiple properties of the coating through the above-mentioned design, which can not only significantly improve the thermal management efficiency of the building facade and reduce air conditioning energy consumption, but also provide long-term and effective fireproofing, super-hydrophobicity and weather-resistant protection for wood structures. It has broad application prospects and market value.

[0066] Compared with the prior art, the present invention has the following beneficial effects:

[0067] (1) The present invention provides a highly solar reflective super-hydrophobic flame-retardant coating, which is prepared by mixing a copolymer Poly (MMA-r-VPA-r-ADH-b-FTMAC), gas-phase nanoparticles, acetone, and water to obtain a coating suspension, which is then sprayed onto a substrate surface and dried. The coating has high solar reflectivity, super-hydrophobicity, and excellent flame-retardant properties.

[0068] (2) The copolymer Poly (MMA-r-VPA-r-ADH-b-FTMAC) in the present invention is prepared from adhesive functional monomers, methyl methacrylate, vinylphosphonic acid, and 2-(perfluorohexyl)ethyl methacrylate by RAFT polymerization technology, wherein vinylphosphonic acid is used to improve the flame retardant properties of the coating, methyl methacrylate plays a film-forming role, the adhesive functional monomer increases the adhesion between the substrate and the coating, and 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°).

[0069] (3) The present invention enhances the light reflectivity 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 (reaching UL-94V-0 level).

[0070] (4) The present invention uses a mixture of acetone and water as a solvent. During the drying process, the rapid evaporation of volatile acetone causes the copolymer to separate from the water phase. After the water evaporates, the coating forms a porous structure (micropores). The porous structure can effectively backscatter sunlight, further enhancing the reflectivity of the present invention (which can reach 95.1%).

[0071] (5) Due to its high solar reflectivity, super hydrophobicity and excellent flame retardant properties, the present invention can be widely used in wooden peripheral structures of buildings, can improve environmental safety, energy saving effects, and is green and environmentally friendly.

[0072] (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. This avoids the reliance on high-precision technology, reduces production costs, and can be widely used in industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0073] Figure 1 Gel permeation chromatography (GPC) test of the copolymer Poly (MMA-r-VPA-r-VA-b-FTMAC);

[0074] Figure 2 Fourier transform infrared spectroscopy (FT-IR) test of the copolymer Poly (MMA-r-VPA-r-VA-b-FTMAC);

[0075] Figure 3 The standard FT-IR spectra of homopolymers Poly VPA, Poly MMA, and Poly VA;

[0076] Figure 4 The phosphorus-31 nuclear magnetic resonance spectrum of the copolymer Poly (MMA-r-VPA-r-VA-b-FTMAC) ( 31 P NMR) test;

[0077] Figure 5 X-ray photoelectron spectroscopy (XPS) test of the copolymer Poly (MMA-r-VPA-r-VA-b-FTMAC);

[0078] Figure 6 This is a cross-sectional scanning electron microscope (SEM) image of the coating prepared in Example 1;

[0079] Figure 7 This is a cross-sectional scanning electron microscope (SEM) image of the coating prepared in Comparative Example 1;

[0080] Figure 8 These are digital photos of Example 1 and Comparative Example 1 sprayed on wood surfaces;

[0081] Figure 9 The reflection spectra of Examples 1 to 6 and Comparative Example 1 in the ultraviolet-visible-near infrared band are shown. DETAILED DESCRIPTION

[0082] This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0083] 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 commercially available.

[0084] A super-hydrophobic flame-retardant coating with high sunlight reflection is obtained by spraying a coating suspension onto a substrate surface and drying the coating suspension. 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 has 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 both of fumed silica, fumed titanium dioxide and fumed aluminum oxide.

[0085] In the coating suspension, the mass ratio of the copolymer Poly (MMA-r-VPA-r-ADH-b-FTMAC) and 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).

[0086] The preparation method of the above coating comprises the following steps:

[0087] S1: Preparation of copolymer Poly (MMA-r-VPA-r-ADH-b-FTMAC);

[0088] S1.1: Mix the adhesive functional monomer, methyl methacrylate, vinylphosphonic acid, chain transfer agent, and acetone to obtain a mixed solution;

[0089] S1.2: Add an initiator to the mixed solution, heat and stir under an inert gas atmosphere to react, and then quench to obtain a first product solution;

[0090] S1.3: Add the first product solution dropwise into diethyl ether to precipitate a solid intermediate product;

[0091] S1.4: Dissolve the solid intermediate product in acetone, add 2-(perfluorohexyl)ethyl methacrylate and an initiator, heat and stir under an inert atmosphere, and then quench to obtain a second product solution.

[0092] S1.5: Add the second product solution dropwise into diethyl ether to precipitate the copolymer Poly (MMA-r-VPA-r-ADH-b-FTMAC);

[0093] S2: dissolving and dispersing 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;

[0094] S3: spraying the coating suspension onto the surface of the substrate through a spraying process, and drying at room temperature to obtain the coating.

[0095] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0096] Example 1

[0097] 1) In a 250 mL eggplant-shaped reaction flask, 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-methylpropionic acid, 0.006 g of azobisisobutyronitrile, and 16 g of acetone were added. Under a nitrogen atmosphere, the temperature was gradually raised to 70°C and the reaction was continued for 24 h. The reaction solution was then quenched to 0°C and added dropwise to 350 mL of diethyl ether to obtain a white solid intermediate.

[0098] 2) The intermediate product of step 1 was dissolved in 16 g of acetone with 0.006 g of azobisisobutyronitrile and 4.16 g of 2-(perfluorohexyl)ethyl methacrylate. The temperature was gradually raised to 70°C under a nitrogen atmosphere and the reaction was continued for 12 h. The reaction solution was then quenched to 0°C and added dropwise to 350 mL of diethyl ether to obtain a white solid copolymer product, Poly (MMA-r-VPA-r-VA-b-FTMAC).

[0099] 3) Take 1g of Poly (MMA-r-VPA-r-VA-b-FTMAC) and dissolve it in a mixed solvent of acetone / water (8g / 0.5g). Then add 0.15g of fumed aluminum oxide and stir to disperse to obtain a suspension coating.

[0100] Example 2

[0101] 1) In a 250 mL eggplant-shaped reaction flask, 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-methylpropionic acid, 0.006 g of azobisisobutyronitrile, and 16 g of acetone were added. Under a nitrogen atmosphere, the temperature was gradually raised to 70°C and the reaction was continued for 24 h. The reaction solution was then quenched to 0°C and added dropwise to 350 mL of diethyl ether to obtain a white solid intermediate.

[0102] 2) The intermediate product of step 1 was dissolved in 16 g of acetone with 0.006 g of azobisisobutyronitrile and 4.16 g of 2-(perfluorohexyl)ethyl methacrylate. The temperature was gradually raised to 70°C under a nitrogen atmosphere and the reaction was continued for 12 h. The reaction solution was then quenched to 0°C and added dropwise to 350 mL of diethyl ether to obtain a white solid copolymer product, Poly (MMA-r-VPA-r-VA-b-FTMAC).

[0103] 3) Take 1g of Poly (MMA-r-VPA-r-VA-b-FTMAC) and dissolve it in a mixed solvent of acetone / water (8g / 0.5g). Then add 0.15g of fumed titanium dioxide and stir to disperse to obtain a suspension coating.

[0104] Example 3

[0105] 1) In a 250 mL eggplant-shaped reaction flask, 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-methylpropionic acid, 0.006 g of azobisisobutyronitrile, and 16 g of acetone were added. Under a nitrogen atmosphere, the temperature was gradually raised to 70°C and the reaction was continued for 24 h. The reaction solution was then quenched to 0°C and added dropwise to 350 mL of diethyl ether to obtain a white solid intermediate.

[0106] 2) The intermediate product of step 1 was dissolved in 16 g of acetone with 0.006 g of azobisisobutyronitrile and 4.16 g of 2-(perfluorohexyl)ethyl methacrylate. The temperature was gradually raised to 70°C under a nitrogen atmosphere and the reaction was continued for 12 h. The reaction solution was then quenched to 0°C and added dropwise to 350 mL of diethyl ether to obtain a white solid copolymer product, Poly (MMA-r-VPA-r-VA-b-FTMAC).

[0107] 3) Take 1g of Poly (MMA-r-VPA-r-VA-b-FTMAC) and dissolve it in a mixed solvent of acetone / water (8g / 0.5g). Then add 0.075g of fumed silica and 0.075g of fumed aluminum oxide, and stir to disperse to obtain a suspension coating.

[0108] Example 4

[0109] 1) In a 250 mL eggplant-shaped reaction flask, 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-methylpropionic acid, 0.006 g of azobisisobutyronitrile, and 16 g of acetone were added. Under a nitrogen atmosphere, the temperature was gradually raised to 70°C and the reaction was continued for 24 h. The reaction solution was then quenched to 0°C and added dropwise to 350 mL of diethyl ether to obtain a white solid intermediate.

[0110] 2) The intermediate product of step 1 was dissolved in 16 g of acetone with 0.006 g of azobisisobutyronitrile and 4.16 g of 2-(perfluorohexyl)ethyl methacrylate. The temperature was gradually raised to 70°C under a nitrogen atmosphere and the reaction was continued for 12 h. The reaction solution was then quenched to 0°C and added dropwise to 350 mL of diethyl ether to obtain a white solid copolymer product, Poly (MMA-r-VPA-r-VA-b-FTMAC).

[0111] 3) Take 1g of Poly (MMA-r-VPA-r-VA-b- FTMAC) and dissolve it in a mixed solvent of acetone / water (8g / 0.5g). Then add 0.075g of fumed titanium dioxide and 0.075g of fumed aluminum oxide, and stir to disperse to obtain a suspension coating.

[0112] Example 5

[0113] 1) In a 250 mL eggplant-shaped reaction flask, 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-methylpropionic acid, 0.006 g of azobisisobutyronitrile, and 16 g of acetone were added. Under a nitrogen atmosphere, the temperature was gradually raised to 70°C and the reaction was continued for 24 h. The reaction solution was then quenched to 0°C and added dropwise to 350 mL of diethyl ether to obtain a white solid intermediate.

[0114] 2) The intermediate product of 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. The reaction solution was then quenched to 0°C and added dropwise to 350 mL of diethyl ether to obtain a white solid copolymer product, Poly(MMA-r-VPA-r-BA-b-FTMAC).

[0115] 3) Take 1g of Poly(MMA-r-VPA-r-BA-b-FTMAC) and dissolve it in a mixed solvent of acetone / water (8g / 0.5g). Then add 0.15g of fumed titanium dioxide and stir to disperse to obtain a suspension coating.

[0116] Example 6

[0117] 1) In a 250 mL eggplant-shaped reaction flask, 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-methylpropionic acid, 0.006 g of azobisisobutyronitrile, and 18 g of acetone were added. Under a nitrogen atmosphere, the temperature was gradually raised to 70°C and the reaction was continued for 24 h. The reaction solution was then quenched to 0°C and added dropwise to 350 mL of diethyl ether to obtain a white solid intermediate.

[0118] 2) The intermediate product of step 1 was dissolved in 18 g of acetone with 0.006 g of azobisisobutyronitrile and 4.16 g of 2-(perfluorohexyl)ethyl methacrylate. The temperature was gradually raised to 70°C under a nitrogen atmosphere and the reaction was continued for 12 h. The reaction solution was then quenched to 0°C and added dropwise to 350 mL of diethyl ether to obtain a white solid copolymer product, Poly(MMA-r-VPA-r-EA-b-FTMAC).

[0119] 3) Take 1g of Poly(MMA-r-VPA-r-EA-b-FTMAC) and dissolve it in a mixed solvent of acetone / water (8g / 0.5g). Then add 0.05g of fumed titanium dioxide and stir to disperse to obtain a suspension coating.

[0120] Comparative Example 1.

[0121] 1) In a 250 mL eggplant-shaped reaction flask, 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-methylpropionic acid, 0.006 g of azobisisobutyronitrile, and 16 g of acetone were added. Under a nitrogen atmosphere, the temperature was gradually raised to 70°C and the reaction was continued for 24 h. The reaction solution was then quenched to 0°C and added dropwise to 350 mL of diethyl ether to obtain a white solid intermediate.

[0122] 2) The intermediate product of step 1 was dissolved in 16 g of acetone with 0.006 g of azobisisobutyronitrile and 4.16 g of 2-(perfluorohexyl)ethyl methacrylate. The temperature was gradually raised to 70°C under a nitrogen atmosphere and the reaction was continued for 12 h. The reaction solution was then quenched to 0°C and added dropwise to 350 mL of diethyl ether to obtain a white solid copolymer product, Poly(MMA-r-VPA-r-VA-b-FTMAC).

[0123] 3) Take 1g of Poly(MMA-r-VPA-r-VA-b- FTMAC ) and dissolve it in a mixed solvent of acetone / water (8g / 0.5g) to obtain a solution coating.

[0124] Comparative Example 2

[0125] 1) In a 250 mL eggplant-shaped reaction flask, 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-methylpropionic acid, 0.006 g of azobisisobutyronitrile, and 16 g of acetone were added. Under a nitrogen atmosphere, the temperature was gradually raised to 70°C and the reaction was continued for 24 h. The reaction solution was then quenched to 0°C and added dropwise to 350 mL of diethyl ether to obtain a white solid intermediate.

[0126] 2) The intermediate product of step 1 was dissolved in 16 g of acetone with 0.006 g of azobisisobutyronitrile and 4.16 g of 2-(perfluorohexyl)ethyl methacrylate. The temperature was gradually raised to 70°C under a nitrogen atmosphere and the reaction was continued for 12 h. The reaction solution was then quenched to 0°C and added dropwise to 350 mL of diethyl ether to obtain a white solid copolymer product, Poly(MMA-r-VPA-r-VA-b-FTMAC).

[0127] 3) Take 1g of Poly(MMA-r-VPA-r-VA-b-FTMAC) and dissolve it in 8.5g of acetone solvent to obtain a solution coating.

[0128] The coatings obtained in Examples 1-6 and Comparative Examples 1-2 were sprayed onto the surface of a fir board and air-dried at room temperature for 6 hours to obtain a coated fir board. The coating was sprayed onto an aluminum foil Petri dish and air-dried at room temperature for 6 hours before being peeled off to obtain a self-supporting coating.

[0129] Figures 1 to 5 The structure of the copolymer product Poly (MMA-r-VPA-r-VA-b-FTMAC) was characterized, which proved the successful polymerization of the monomers and the acquisition of the copolymer.

[0130] Figure 1 The GPC test results of Poly (MMA-r-VPA-r-VA-b-FTMAC) were presented, showing a single chromatographic peak within the retention time range of 6.8 min to 9.9 min, with a number average molecular weight (Mn) of 30278 g / mol, confirming the successful synthesis of the target single polymer with uniform molecular weight distribution.

[0131] Figure 2 This is the FT-IR spectrum of Poly (MMA-r-VPA-r-VA-b-FTMAC). The positions of the characteristic peaks are consistent with the standard peak positions of the corresponding monomers (methyl methacrylate (MMA), vinyl phosphonic acid (VPA), and vinyl acetate (VA)) homopolymers ( Figure 3 ).

[0132] Figure 4 Poly (MMA-r-VPA-r-VA-b-FTMAC)31 The P NMR spectrum shows a major peak chemical shift at approximately 31 ppm, consistent with the characteristic signal of the phosphorus atom in the phosphate group O=P(OH)2. The single peak position indicates the presence of polyethylene phosphate segments in the copolymer, and no significant interfering peaks from free phosphate or hydrolysis byproducts were detected, further confirming the structural integrity of the target copolymer.

[0133] Figure 5 XPS results show multiple characteristic binding energy peaks. P2p (approximately 131 eV) and P2s (approximately 189 eV) correspond to the characteristic binding energies of phosphorus atoms in the O=P(OH)2 group, indicating the presence of poly(vinyl phosphate) segments in the copolymer. C1s (approximately 285 eV) is attributed to contributions from carbon-carbon / carbon-hydrogen (C-C-H) bonds in the backbone and side chains, along with a small amount of carbon from the ester (C=O) group. O1s (approximately 532 eV) originates from oxygen atoms in the ester (C=O) and phosphate (PO) groups. F1s (approximately 689 eV) corresponds to the characteristic peak of fluorine atoms in the perfluorohexyl segment, confirming the successful introduction of the fluorinated hydrophobic segment.

[0134] Figure 6 and Figure 7 The scanning electron microscope images of Example 1 and Comparative Example 1 after drying in air are shown. The rapid evaporation of volatile acetone causes the Poly (MMA-r-VPA-r-VA-b-FTMAC) of Comparative Example 1 to separate from the water phase. After the water evaporates, micropores are formed in the coating ( Figure 6 The yellow dotted line in the middle) effectively backscatters sunlight, so the coating appears white visually ( Figure 8 This structural characteristic gives the coating excellent sunlight reflection capabilities. Furthermore, the coating design in Example 1, combining randomly distributed fumed aluminum oxide particles with a porous polymer structure, can achieve even more significant light scattering enhancement, effectively reducing heat accumulation on the wood surface. This significantly contributes to building energy conservation, especially in hot climates.

[0135] Figure 9 The reflectance data for Examples 1-6 and Comparative Example 1 in the UV-Vis-NIR band (measured using a UV-VIS-NIR spectrophotometer) show that the coatings incorporating vapor-phase nanoparticles exhibit significantly higher reflectance than Comparative Example 1. This means that wooden exterior building walls coated with the coatings of this invention can effectively prevent heat accumulation under intense sunlight, further improving building energy efficiency.

[0136] Table 1 Performance parameters of Examples 1 to 6 and Comparative Example 1

[0137]

[0138] Table 1 is a performance parameter table of Examples 1 to 6 and Comparative Examples 1-2. As can be seen from Table 1, the coating prepared by the present invention has a higher solar reflectance and can also meet the flame retardant standard of UL-94 V-0 level, proving its excellent flame retardant performance. Compared with existing wood substrate coatings, the coating of the present invention has a significant improvement in fire safety, can effectively reduce fire hazards, and provide higher safety protection. In addition, the coatings in Examples 1 to 6 show excellent super-hydrophobicity, and the water contact angle can reach 150 °. This is mainly due to the self-enrichment of the poly-2-(perfluorohexyl)ethyl methacrylate segment on the air side during the drying process, which improves the hydrophobicity of the coating surface.

[0139] In summary, the present invention provides a highly solar reflective super-hydrophobic flame-retardant coating, which has high solar reflectivity, super-hydrophobicity, and excellent flame-retardant properties. It can be widely used in a variety of fields such as building wood and exterior wall coatings, and has significant energy-saving, environmental protection, and safety performance.

[0140] The above description of the embodiments is intended to facilitate understanding and use of the invention by those skilled in the art. It will be apparent that those skilled in the art can readily make various modifications to these embodiments and apply the general principles described herein to other embodiments without requiring inventive effort. Therefore, the present invention is not limited to the above-described embodiments. Improvements and modifications made by those skilled in the art based on the disclosure of the present invention, without departing from the scope of the present invention, should be within the scope of protection of the present invention.

Claims

1. A super hydrophobic flame retardant coating with high sunlight reflection, 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: Wherein, ADH is a bonding functional monomer, including any one of vinyl acetate, n-butyl methacrylate, and 2-ethylhexyl acrylate, and the value ranges of x, y, z, and k are: 70 <x<250、35<y<100、25<z<100、10<k<100; The copolymer Poly (MMA-r-VPA-r-ADH-b-FTMAC) is prepared from a bonding functional monomer, methyl methacrylate, vinylphosphonic acid, and 2-(perfluorohexyl)ethyl methacrylate by reversible addition-fragmentation chain transfer polymerization technology; The thickness of the coating is not less than 50 μm, and the coating is a porous structure with a porosity of 30% to 70% and a specific surface area of ​​50 to 200 m 2 / g, pore size is 0.5~5μm.

2. A highly solar reflective super-hydrophobic flame-retardant coating according to claim 1, characterized in that: The molar fractions of the monomeric raw materials of the copolymer Poly(MMA-r-VPA-r-ADH-b-FTMAC) are as follows:

3. A highly solar reflective super-hydrophobic flame-retardant coating according to claim 1, characterized in that: The gas-phase nanoparticles include one or two of gas-phase silicon dioxide, gas-phase titanium dioxide, and gas-phase aluminum oxide. The mass ratio of the copolymer Poly(MMA-r-VPA-r-ADH-b-FTMAC) and the gas-phase nanoparticles is 1:0.05-0.45, and the mass ratio of the sum of the 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.

4. A method for preparing a highly solar reflective super-hydrophobic flame-retardant coating according to any one of claims 1 to 3, characterized in that: The steps include: S1: Preparation of copolymer Poly(MMA-r-VPA-r-ADH-b-FTMAC); S2: dissolving and dispersing 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: spraying the coating suspension onto the surface of the substrate through a spraying process, and drying at room temperature to obtain the coating.

5. The method for preparing a super-hydrophobic flame-retardant coating with high sunlight reflection according to claim 4, wherein: Step S1 specifically includes the following steps: S1.1: Mix the adhesive functional monomer, methyl methacrylate, vinylphosphonic acid, chain transfer agent, and acetone to obtain a mixed solution; S1.2: Add an initiator to the mixed solution, heat and stir under an inert gas atmosphere to react, and then quench to obtain a first product solution; S1.3: Add the first product solution dropwise 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 under an inert atmosphere, and then quench to obtain a second product solution. S1.5: The second product solution was dropped into diethyl ether to precipitate and obtain the copolymer Poly(MMA-r-VPA-r-ADH-b-FTMAC).

6. The method for preparing a super-hydrophobic flame-retardant coating with high sunlight reflection according to claim 5, wherein: In step S1.1, the amount of the chain transfer agent is 0.02% to 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% to 60wt%; the chain transfer agent includes 2-[dodecylthio(thiocarbonyl)thio]-2-methylpropionic 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 hours, the quenching temperature is -4-5°C, and the amount of the initiator used 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 to 20:1; In step S1.4, the sum of the mass of the solid intermediate product and 2-(perfluorohexyl)ethyl methacrylate accounts for 45-60% of the sum of the mass 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, and the time is 8-16 hours; the quenching temperature is -4-5°C; the amount of the initiator used is 5-50% of the molar amount of the chain transfer reagent in step S1.1, and the initiator includes azobisisobutyronitrile; In step S1.5, the volume ratio of the diethyl ether to the second product solution is 8:1 to 20:

1.

7. The method for preparing a super-hydrophobic flame-retardant coating with high sunlight reflection according to claim 4, wherein: 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 hours.

8. Use of the highly solar-reflective super-hydrophobic flame-retardant coating according to any one of claims 1 to 3 in the field of building facade coatings.

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