Building exterior wall coating and preparation method thereof

Abstract

The invention discloses a building exterior wall coating and a preparation method thereof, and relates to the technical field of coatings. When the building exterior wall coating is prepared, an azo intermediate, iron powder and hydrochloric acid react to prepare a benzotriazole monomer; carrying out a reaction on the secondary substituted cyanuric chloride and 4-pentene-1-amine to prepare a modified cyanuric chloride monomer; carrying out reaction on the polyurethane prepolymer and phosphorus-containing diamine to prepare a phosphorus-containing curing agent; ethyl acrylate, acrylic acid [2-(oxirane-2-yl) ethyl] ester, a benzotriazole monomer, a modified cyanuric chloride monomer, azodiisobutyronitrile and propylene glycol monomethyl ether acetate are subjected to a reaction, and an acrylic resin solution is prepared; the acrylic resin solution, a dispersing agent, a defoaming agent, silicon dioxide, calcined stone, a wetting agent, a flatting agent, a thickening agent and a phosphorus-containing curing agent are subjected to pulping and paint mixing, and the building exterior wall coating is prepared. The building exterior wall coating prepared by the invention has excellent flame-retardant, hydrophobic and anti-aging properties.

Description

Technical Field

[0001] This invention relates to the field of coating technology, specifically to an exterior wall coating for buildings and its preparation method. Background Technology

[0002] Acrylic coatings have become the mainstream choice for building exterior wall coatings due to their excellent weather resistance, rich decorative properties, and environmental friendliness. However, with the development of modern buildings towards high-rise, dense, and iconic structures, the protective and decorative functions of exterior wall coatings can no longer meet the ever-growing demands, and the limitations of traditional building exterior wall coatings are becoming increasingly apparent. The flammable nature of traditional organic exterior wall coatings often makes them a medium for flame propagation in high-rise and super high-rise building fires, posing significant safety hazards. Building exterior wall coatings are exposed to complex environments such as ultraviolet radiation and moisture for extended periods, commonly exhibiting problems such as chalking, yellowing, and loss of gloss, leading to premature failure of the decorative effect and increased maintenance costs. Simultaneously, rainwater washes away stains on the building surface, affecting aesthetics, and even moisture penetrating into the wall can cause durability problems such as dampness, mold, and even peeling. Therefore, developing a multifunctional integrated building exterior wall coating with long-lasting flame retardancy, excellent weather resistance, and highly efficient hydrophobicity has become a key trend in the industry. Summary of the Invention

[0003] The purpose of this invention is to provide an exterior wall coating and its preparation method to solve the problems existing in the prior art.

[0004] To solve the above-mentioned technical problems, the present invention provides the following solution: An exterior wall coating is prepared by reacting an azo intermediate, iron powder, and hydrochloric acid to obtain a benzotriazole monomer; reacting a secondary substituted cyanuric chloride with 4-penten-1-amine to obtain a modified cyanuric chloride monomer; reacting a polyurethane prepolymer with a phosphorus-containing diamine to obtain a phosphorus-containing curing agent; reacting ethyl acrylate, [2-(ethylene oxide-2-yl)ethyl] acrylate, benzotriazole monomer, modified cyanuric chloride monomer, azobisisobutyronitrile, and propylene glycol monomethyl ether acetate to obtain an acrylic resin solution; and mixing the acrylic resin solution, dispersant, defoamer, silica, calcined stone, wetting agent, leveling agent, thickener, and phosphorus-containing curing agent to form a paste and paint. The azo intermediate is prepared by reacting 2-vinylphenol with a diazonium salt solution; The diazonium salt solution is prepared by reacting 4-methyl-2-nitroaniline, an aqueous sulfuric acid solution, and an aqueous sodium nitrite solution. The secondary substituted cyanuric chloride is prepared by reacting a primary substituted cyanuric chloride with 1H,1H-undecylfluorohexylamine. The aforementioned primary substituted cyanuric chloride is prepared by reacting cyanuric chloride with 1H,1H-undecylfluorohexylamine. The polyurethane prepolymer is prepared by reacting isophorone diisocyanate and 2,2-dimethylolpropionic acid. The phosphorus-containing diamine is prepared by reacting but-2-ene-1,4-diamine and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide.

[0005] A method for preparing an exterior wall coating, the method comprising the following preparation steps: (1) Mix the azo intermediate, iron powder, and 6M hydrochloric acid in a mass ratio of 1:(1~1.2):(5~7) until homogeneous. Stir and reflux at 300~500r / min at 80~100℃ for 4~6h. Cool to room temperature, filter, adjust the pH of the filtrate to 7~8 with saturated sodium hydroxide solution, filter, and dry at 80~100℃ for 8~10h to obtain benzotriazole monomer; (2) Add equimolar amounts of 4-penten-1-amine and saturated sodium hydroxide aqueous solution to the secondary substituted cyanuric chloride, heat to 85~95℃, continue stirring for 7~9h, cool to room temperature, filter, wash 3~5 times with acetone and deionized water respectively, and dry at 60~80℃ for 12~14h to obtain the modified cyanuric chloride monomer. (3) The polyurethane prepolymer, phosphorus-containing diamine, and N,N-dimethylformamide are mixed evenly at a mass ratio of 1:(1~1.2):(8~10). Under nitrogen protection, the mixture is stirred at 500~800 r / min for 2~3 h at room temperature. Deionized water with a mass of 4~5 times that of N,N-dimethylformamide is added, and the mixture is stirred at 800~1000 r / min for 20~30 min. After precipitation, the mixture is filtered, washed 3~5 times with deionized water, and vacuum dried at 40~60℃ for 30~36 h to obtain the phosphorus-containing curing agent. (4) Mix 100-120 parts of acrylic resin solution, 1.6-2 parts of dispersant, and 0.4-0.8 parts of defoamer evenly, stir at 1000-1400 r / min for 10-20 min, add 10-20 parts of silica and 80-100 parts of calcined stone, continue stirring for 30-40 min, add 0.4-0.6 parts of wetting agent, 0.4-0.8 parts of leveling agent, 1.4-1.8 parts of thickener and 20-30 parts of phosphorus-containing curing agent, stir at 500-700 r / min for 10-20 min to obtain building exterior wall coating.

[0006] As an optimization, the preparation method of the azo intermediate in step (1) is as follows: 2-vinylphenol is dissolved in a sodium carbonate aqueous solution with a mass ratio of 5% to 0.4 to 0.6 times that of 4-methyl-2-nitroaniline, stirred at 300 to 500 r / min for 10 to 20 min, cooled to 0 to 4℃, and a diazonium salt solution is added uniformly within 30 to 50 min. The reaction is continued to be stirred for 1 to 2 h, filtered, washed 3 to 5 times with cold deionized water, and dried at 80 to 100℃ for 8 to 10 h to obtain the azo intermediate.

[0007] As an optimization, the preparation method of the azo intermediate in step (1) is as follows: 2-vinylphenol is dissolved in a sodium carbonate aqueous solution with a mass ratio of 5% to 0.4 to 0.6 times that of 4-methyl-2-nitroaniline, stirred at 300 to 500 r / min for 10 to 20 min, cooled to 0 to 4℃, and a diazonium salt solution is added uniformly within 30 to 50 min. The reaction is continued to be stirred for 1 to 2 h, filtered, washed 3 to 5 times with cold deionized water, and dried at 80 to 100℃ for 8 to 10 h to obtain the azo intermediate.

[0008] First, a diazonium salt solution is prepared by diazotization of 4-methyl-2-nitroaniline, sulfuric acid aqueous solution, and sodium nitrite aqueous solution. The diazonium salt solution is then coupled with 2-vinylphenol to prepare an azo intermediate. The azo intermediate is then reduced and cyclized with iron powder and hydrochloric acid to obtain the benzotriazole monomer. The ortho-hydroxy nitrogen heterocycle in the benzotriazole structure transitions from the ground state to the excited state after absorbing high-energy ultraviolet light. The excited state energy is efficiently converted into harmless heat energy and released through the breaking and regeneration cycle of intramolecular hydrogen bonds. The benzotriazole molecule converts ultraviolet light energy into heat energy and dissipates it through the reversible change of its own structure, preventing ultraviolet light energy from directly acting on the resin polymer chain. This fundamentally inhibits the resin chain breakage and free radical oxidation caused by ultraviolet light, thereby endowing the building exterior wall coating with excellent anti-aging properties.

[0009] Secondly, cyanuric chloride and 1H,1H-undecylfluorohexylamine were reacted to prepare a primary substituted cyanuric chloride; the primary substituted cyanuric chloride was then reacted with 1H,1H-undecylfluorohexylamine to prepare a secondary substituted cyanuric chloride, and fluorocarbon chains were grafted onto the cyanuric chloride; the secondary substituted cyanuric chloride was then reacted with 4-penten-1-amine to prepare a modified cyanuric chloride monomer; through the modification of cyanuric chloride, fluorocarbon chains and triazine ring structures were introduced into acrylic resin; the fluorocarbon chains have extremely low surface energy, and when this monomer participates in the curing of building exterior wall coatings, these fluorocarbon chains spontaneously migrate to the coating surface and arrange themselves tightly, forming a dense low surface energy barrier, preventing water or common oily pollutants from spreading smoothly on the coating surface, thus giving the building exterior wall coating excellent hydrophobic properties; the triazine ring conjugated system can efficiently absorb 290-400 nm. When ultraviolet light in the m-band is absorbed, the molecules transition from the ground state to the excited state. The energy of the excited state is converted into heat energy through rapid and reversible intramolecular proton transfer and electronic reconstruction, thus effectively "intercepting" and eliminating ultraviolet photons, thereby further improving the anti-aging performance of building exterior wall coatings. At the same time, under high temperature or combustion conditions, the triazine ring structure can rapidly decompose, catalyzing the dehydration and cross-linking of the polymer matrix, forming a dense and stable expanded char layer in the condensed phase, and releasing non-flammable nitrogen and ammonia. These gases not only dilute the concentration of flammable gases and oxygen, but also make the char layer more fluffy and solid through expansion. The expanded char layer can act as a physical barrier to prevent heat and oxygen from being transferred to the building substrate, inhibit the escape of flammable volatiles, thereby interrupting the combustion cycle and giving building exterior wall coatings excellent flame retardant properties.

[0010] Finally, isophorone diisocyanate and 2,2-dimethylolpropionic acid were reacted to prepare a polyurethane prepolymer; but-2-ene-1,4-diamine and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide were reacted to prepare a phosphorus-containing diamine; the polyurethane prepolymer and the phosphorus-containing diamine were reacted to prepare an amino-terminated phosphorus-containing curing agent, and a DOPO structure was introduced into the polyurethane curing agent; when the coating is exposed to a fire source or high temperature, the DOPO structure will decompose first to form strongly dehydrating substances such as phosphoric acid and metaphosphoric acid, which can catalyze the dehydration and carbonization of the polymer matrix and the nitrogen-containing but-2-ene-1,4-diamine and triazine ring components to form an expanded carbon layer, thereby further improving the flame retardant performance of the building exterior wall coating. Detailed Implementation

[0011] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0012] In the following examples and comparative examples, the dispersant used was Dispex AA 4141, the wetting agent was TEGOWet 280, the defoamer was CT-851, the leveling agent was Glide 410, the thickener was RG-JZ600, the silica particle size was 2000 mesh, and the calcined stone particle size was 4000 mesh.

[0013] Example 1: A method for preparing an exterior wall coating, the method comprising the following steps: (1) Weigh 4-methyl-2-nitroaniline, sodium nitrite and 2-vinylphenol in a molar ratio of 1:1:1; mix 4-methyl-2-nitroaniline and 20% sulfuric acid aqueous solution in a mass ratio of 1:8, stir at 0℃ and 300r / min for 20min, add 20% sodium nitrite aqueous solution at a uniform rate over 40min, and continue stirring for 2h to obtain a diazonium salt solution; dissolve 2-vinylphenol in 0.4 times the mass of 4-methyl-2-nitroaniline in a 5% sodium carbonate aqueous solution. The mixture was stirred at 300 rpm for 20 min, cooled to 0 °C, and a diazonium salt solution was added at a uniform rate over 50 min. The reaction was continued with stirring for 2 h. The mixture was filtered, washed three times with cold deionized water, and dried at 80 °C for 10 h to obtain the azo intermediate. The azo intermediate, iron powder, and 6 M hydrochloric acid were mixed evenly at a mass ratio of 1:1:5 and refluxed at 300 rpm for 6 h at 80 °C. The mixture was cooled to room temperature, filtered, and the filtrate was adjusted to pH 7 with saturated sodium hydroxide solution. The mixture was filtered again and dried at 80 °C for 10 h to obtain the benzotriazole monomer. (2) Weigh cyanuric chloride, 1H,1H-undecylfluorohexylamine and sodium hydroxide in a molar ratio of 1:1:1. Mix cyanuric chloride and acetone in a mass ratio of 1:8. Add 1H,1H-undecylfluorohexylamine and saturated sodium hydroxide aqueous solution. Cool to 0°C and stir at 300 r / min for 4 h to obtain a primary substituted cyanuric chloride. Add 1H,1H-undecylfluorohexylamine and saturated sodium hydroxide aqueous solution to the primary substituted cyanuric chloride. Heat to 45°C and continue stirring for 9 h to obtain a secondary substituted cyanuric chloride. Add 4-penten-1-amine and saturated sodium hydroxide aqueous solution to the secondary substituted cyanuric chloride. Heat to 85°C and continue stirring for 9 h. Cool to room temperature, filter, wash three times with acetone and deionized water respectively, and dry at 60°C for 14 h to obtain a modified cyanuric chloride monomer. (3) Isophorone diisocyanate, 2,2-dimethylolpropionic acid, N,N-dimethylformamide, and dibutyltin dilaurate were mixed evenly in a mass ratio of 1:1.2:8:0.02, heated to 60°C under nitrogen protection, and stirred at 300 r / min for 6 h to obtain a polyurethane prepolymer; but-2-ene-1,4-diamine and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide were mixed evenly in a mass ratio of 1:2 and heated to 140°C. The reaction was stirred at 300 r / min for 10 h to obtain phosphorus-containing diamine; polyurethane prepolymer, phosphorus-containing diamine, and N,N-dimethylformamide were mixed evenly at a mass ratio of 1:1:8, and stirred at 500 r / min for 3 h at room temperature under nitrogen protection. Deionized water with a mass of 4 times that of N,N-dimethylformamide was added, and the mixture was stirred at 800 r / min for 30 min. After precipitation, the mixture was filtered, washed 3 times with deionized water, and dried under vacuum at 40℃ for 36 h to obtain phosphorus-containing curing agent. (4) By mass, 25 parts of ethyl acrylate, 15 parts of [2-(ethylene oxide-2-yl)ethyl] acrylate, 10 parts of benzotriazole monomer, 8 parts of modified cyanuric chloride monomer, 0.5 parts of azobisisobutyronitrile and 40 parts of propylene glycol monomethyl ether acetate are mixed evenly, heated to 80°C under nitrogen protection, stirred at 500 r / min for 6 h, and cooled to room temperature to obtain an acrylic resin solution; 100 parts of acrylic resin solution, 1.6 parts of dispersant and 0.4 parts of defoamer are mixed evenly, stirred at 1000 r / min for 20 min, 10 parts of silica and 80 parts of calcined stone are added, and stirring is continued for 40 min, 0.4 parts of wetting agent, 0.4 parts of leveling agent, 1.4 parts of thickener and 20 parts of phosphorus-containing curing agent are added, and stirred at 500 r / min for 20 min to obtain an exterior wall coating.

[0014] Example 2: A method for preparing an exterior wall coating, the method comprising the following steps: (1) Weigh 4-methyl-2-nitroaniline, sodium nitrite and 2-vinylphenol in a molar ratio of 1:1:1; mix 4-methyl-2-nitroaniline and 20% sulfuric acid aqueous solution in a mass ratio of 1:9, stir at 2℃ and 400r / min for 15min, add 20% sodium nitrite aqueous solution at a uniform rate over 35min, and continue stirring for 1.5h to obtain a diazonium salt solution; dissolve 2-vinylphenol in 0.5 times the mass of 4-methyl-2-nitroaniline in a 5% sodium carbonate aqueous solution. The mixture was stirred at 400 rpm for 15 min, cooled to 2 °C, and a diazonium salt solution was added at a uniform rate over 40 min. The reaction was continued with stirring for 1.5 h. The mixture was filtered, washed four times with cold deionized water, and dried at 90 °C for 9 h to obtain the azo intermediate. The azo intermediate, iron powder, and 6 M hydrochloric acid were mixed evenly at a mass ratio of 1:1.1:6. The mixture was stirred and refluxed at 400 rpm for 5 h at 90 °C. After cooling to room temperature, the mixture was filtered. The pH of the filtrate was adjusted to 7.5 with saturated sodium hydroxide solution, filtered, and dried at 90 °C for 9 h to obtain the benzotriazole monomer. (2) Weigh cyanuric chloride, 1H,1H-undecylfluorohexylamine and sodium hydroxide in a molar ratio of 1:1:1. Mix cyanuric chloride and acetone in a mass ratio of 1:9. Add 1H,1H-undecylfluorohexylamine and saturated sodium hydroxide aqueous solution. Cool to 2°C and stir at 400 r / min for 3.5 h to obtain a primary substituted cyanuric chloride. Add 1H,1H-undecylfluorohexylamine and saturated sodium hydroxide aqueous solution to the primary substituted cyanuric chloride. Heat to 50°C and continue stirring for 8 h to obtain a secondary substituted cyanuric chloride. Add 4-penten-1-amine and saturated sodium hydroxide aqueous solution to the secondary substituted cyanuric chloride. Heat to 90°C and continue stirring for 8 h. Cool to room temperature, filter, wash 4 times with acetone and deionized water respectively, and dry at 70°C for 13 h to obtain a modified cyanuric chloride monomer. (3) Isophorone diisocyanate, 2,2-dimethylolpropionic acid, N,N-dimethylformamide, and dibutyltin dilaurate were mixed evenly in a mass ratio of 1:1.3:9:0.03, heated to 65°C under nitrogen protection, and stirred at 400 r / min for 5.5 h to obtain a polyurethane prepolymer; but-2-ene-1,4-diamine and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide were mixed evenly in a mass ratio of 1:2.5 and heated to 145°C. The reaction mixture was stirred at 400 rpm for 9 h to obtain phosphorus-containing diamine. Polyurethane prepolymer, phosphorus-containing diamine, and N,N-dimethylformamide were mixed evenly at a mass ratio of 1:1.1:9. Under nitrogen protection, the mixture was stirred at 650 rpm for 2.5 h at room temperature. Deionized water with a mass of 4.5 times that of N,N-dimethylformamide was added, and the mixture was stirred at 900 rpm for 25 min. After precipitation, the mixture was filtered, washed four times with deionized water, and dried under vacuum at 50 °C for 33 h to obtain a phosphorus-containing curing agent. (4) By mass, 30 parts of ethyl acrylate, 20 parts of [2-(ethylene oxide-2-yl)ethyl] acrylate, 12 parts of benzotriazole monomer, 9 parts of modified cyanuric chloride monomer, 1 part of azobisisobutyronitrile and 45 parts of propylene glycol monomethyl ether acetate are mixed evenly, heated to 85°C under nitrogen protection, stirred at 600 r / min for 5 h, and cooled to room temperature to obtain an acrylic resin solution; 110 parts of acrylic resin solution, 1.8 parts of dispersant and 0.6 parts of defoamer are mixed evenly, stirred at 1200 r / min for 15 min, 15 parts of silica and 90 parts of calcined stone are added, and stirring is continued for 35 min, 0.5 parts of wetting agent, 0.6 parts of leveling agent, 1.6 parts of thickener and 25 parts of phosphorus-containing curing agent are added, and stirred at 600 r / min for 15 min to obtain an exterior wall coating.

[0015] Example 3: A method for preparing an exterior wall coating, the method comprising the following steps: (1) Weigh 4-methyl-2-nitroaniline, sodium nitrite and 2-vinylphenol in a molar ratio of 1:1:1; mix 4-methyl-2-nitroaniline and 20% sulfuric acid aqueous solution in a mass ratio of 1:10, stir at 500 r / min for 10 min at 4℃, add 20% sodium nitrite aqueous solution at a uniform rate over 30 min, and continue stirring for 1 h to obtain a diazonium salt solution; dissolve 2-vinylphenol in a 5% sodium carbonate aqueous solution with a mass ratio of 0.6 times that of 4-methyl-2-nitroaniline. The mixture was stirred at 500 rpm for 10 min, cooled to 4 °C, and a diazonium salt solution was added at a uniform rate over 30 min. The reaction was continued with stirring for 1 h. The mixture was filtered, washed 5 times with cold deionized water, and dried at 100 °C for 8 h to obtain the azo intermediate. The azo intermediate, iron powder, and 6 M hydrochloric acid were mixed evenly at a mass ratio of 1:1.2:7. The mixture was stirred and refluxed at 100 °C and 500 rpm for 4 h. After cooling to room temperature, the mixture was filtered. The filtrate was adjusted to pH 8 with saturated sodium hydroxide solution, filtered, and dried at 100 °C for 8 h to obtain the benzotriazole monomer. (2) Weigh cyanuric chloride, 1H,1H-undecylfluorohexylamine and sodium hydroxide in a molar ratio of 1:1:1. Mix cyanuric chloride and acetone in a mass ratio of 1:10. Add 1H,1H-undecylfluorohexylamine and saturated sodium hydroxide aqueous solution. Cool to 4°C and stir at 500 r / min for 3 h to obtain a primary substituted cyanuric chloride. Add 1H,1H-undecylfluorohexylamine and saturated sodium hydroxide aqueous solution to the primary substituted cyanuric chloride. Heat to 55°C and continue stirring for 7 h to obtain a secondary substituted cyanuric chloride. Add 4-penten-1-amine and saturated sodium hydroxide aqueous solution to the secondary substituted cyanuric chloride. Heat to 95°C and continue stirring for 7 h. Cool to room temperature, filter, wash 5 times with acetone and deionized water respectively, and dry at 80°C for 12 h to obtain a modified cyanuric chloride monomer. (3) Isophorone diisocyanate, 2,2-dimethylolpropionic acid, N,N-dimethylformamide, and dibutyltin dilaurate were mixed evenly in a mass ratio of 1:1.4:10:0.04. Under nitrogen protection, the mixture was heated to 70°C and stirred at 500 r / min for 5 h to obtain a polyurethane prepolymer. But-2-ene-1,4-diamine and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide were mixed evenly in a mass ratio of 1:3 and heated to 150°C. Phosphorus-containing diamine was prepared by stirring at 500 r / min for 8 h; polyurethane prepolymer, phosphorus-containing diamine, and N,N-dimethylformamide were mixed evenly at a mass ratio of 1:1.2:10, and stirred at 800 r / min for 2 h at room temperature under nitrogen protection. Five times the mass of deionized water of N,N-dimethylformamide was added, and the mixture was stirred at 1000 r / min for 20 min. After precipitation, the mixture was filtered, washed five times with deionized water, and dried under vacuum at 60℃ for 30 h to obtain a phosphorus-containing curing agent. (4) By mass, 35 parts of ethyl acrylate, 25 parts of [2-(ethylene oxide-2-yl)ethyl] acrylate, 14 parts of benzotriazole monomer, 10 parts of modified cyanuric chloride monomer, 1.5 parts of azobisisobutyronitrile and 50 parts of propylene glycol monomethyl ether acetate are mixed evenly, heated to 90°C under nitrogen protection, stirred at 700 r / min for 4 h, and cooled to room temperature to obtain an acrylic resin solution; 120 parts of acrylic resin solution, 2 parts of dispersant and 0.8 parts of defoamer are mixed evenly, stirred at 1400 r / min for 10 min, 20 parts of silica and 100 parts of calcined stone are added, and stirring is continued for 30 min, 0.6 parts of wetting agent, 0.8 parts of leveling agent, 1.8 parts of thickener and 30 parts of phosphorus-containing curing agent are added, and stirred at 700 r / min for 10 min to obtain an exterior wall coating.

[0016] Comparative Example 1: The difference between the preparation method of the building exterior wall coating of Comparative Example 1 and Example 2 is that step (1) is omitted, and step (4) is changed to: by mass parts, 30 parts of ethyl acrylate, 20 parts of [2-(ethylene oxide-2-yl)ethyl] acrylate, 9 parts of modified cyanuric chloride monomer, 1 part of azobisisobutyronitrile and 45 parts of propylene glycol monomethyl ether acetate are mixed evenly, heated to 85°C under nitrogen protection, stirred at 600 r / min for 5 h, and cooled to room temperature to obtain an acrylic resin solution; 110 parts of acrylic resin solution, 1.8 parts of dispersant and 0.6 parts of defoamer are mixed evenly, stirred at 1200 r / min for 15 min, 15 parts of silica and 90 parts of calcined stone are added, and stirring is continued for 35 min, 0.5 parts of wetting agent, 0.6 parts of leveling agent, 1.6 parts of thickener and 25 parts of phosphorus-containing curing agent are added, and stirred at 600 r / min for 15 min to obtain the building exterior wall coating. The remaining steps are the same as in Example 2.

[0017] Comparative Example 2 The preparation method of the building exterior wall coating in Comparative Example 2 differs from that in Example 2 only in that step (2) is changed as follows: Melamine, n-hexylamine, and sodium hydroxide are weighed in a molar ratio of 1:1:1. Melamine and acetone are mixed evenly in a mass ratio of 1:9. Hexylamine and a saturated sodium hydroxide aqueous solution are added, the temperature is lowered to 2°C, and the mixture is stirred at 400 r / min for 3.5 h to obtain a primary substituted melamine. An equimolar amount of hexylamine and a saturated sodium hydroxide aqueous solution are added to the primary substituted melamine. The temperature is raised to 50°C, and the mixture is stirred for 8 h to obtain a secondary substituted melamine. An equimolar amount of 4-penten-1-amine and a saturated sodium hydroxide aqueous solution are added to the secondary substituted melamine. The temperature is raised to 90°C, and the mixture is stirred for 8 h. The mixture is cooled to room temperature, filtered, washed four times with acetone and deionized water respectively, and dried at 70°C for 13 h to obtain the modified melamine monomer. The remaining steps are the same as in Example 2.

[0018] Comparative Example 3 The difference between the preparation method of the building exterior wall coating of Comparative Example 3 and Example 2 is that step (2) is omitted, and step (4) is changed to: by mass parts, 30 parts of ethyl acrylate, 20 parts of [2-(ethylene oxide-2-yl)ethyl] acrylate, 12 parts of benzotriazole monomer, 1 part of azobisisobutyronitrile and 45 parts of propylene glycol monomethyl ether acetate are mixed evenly, heated to 85°C under nitrogen protection, stirred at 600 r / min for 5 h, and cooled to room temperature to obtain an acrylic resin solution; 110 parts of acrylic resin solution, 1.8 parts of dispersant and 0.6 parts of defoamer are mixed evenly, stirred at 1200 r / min for 15 min, 15 parts of silica and 90 parts of calcined stone are added, and stirring is continued for 35 min, 0.5 parts of wetting agent, 0.6 parts of leveling agent, 1.6 parts of thickener and 25 parts of phosphorus-containing curing agent are added, and stirred at 600 r / min for 15 min to obtain the building exterior wall coating. The remaining steps are the same as in Example 2.

[0019] Comparative Example 4 The difference between the preparation method of the building exterior wall coating in Comparative Example 4 and Example 2 is that step (3) is changed to: isophorone diisocyanate, 2,2-dimethylolpropionic acid, N,N-dimethylformamide, and dibutyltin dilaurate are mixed evenly in a mass ratio of 1:1.3:9:0.03, heated to 65°C under nitrogen protection, and stirred at 400 r / min for 5.5 h to obtain polyurethane prepolymer; polyurethane prepolymer, 1,3-propanediamine, and N,N-dimethylformamide are mixed evenly in a mass ratio of 1:1.1:9, and stirred at 650 r / min for 2.5 h under nitrogen protection at room temperature, then 4.5 times the mass of deionized water is added, stirred at 900 r / min for 25 min, precipitated, filtered, washed 4 times with deionized water, and vacuum dried at 50°C for 33 h to obtain amino-terminated cured coating. The following steps are modified: 30 parts by mass of ethyl acrylate, 20 parts by mass of [2-(ethylene oxide-2-yl)ethyl] acrylate, 12 parts by mass of benzotriazole monomer, 9 parts by mass of modified cyanuric chloride monomer, 1 part by mass of azobisisobutyronitrile and 45 parts by mass of propylene glycol monomethyl ether acetate are mixed evenly, heated to 85°C under nitrogen protection, stirred at 600 r / min for 5 h, and cooled to room temperature to obtain an acrylic resin solution; 110 parts by mass of acrylic resin solution, 1.8 parts by mass of dispersant and 0.6 parts by mass of defoamer are mixed evenly, stirred at 1200 r / min for 15 min, 15 parts by mass of silica and 90 parts by mass of calcined stone are added, and stirring is continued for 35 min, 0.5 parts by mass of wetting agent, 0.6 parts by mass of leveling agent, 1.6 parts by mass of thickener and 25 parts by mass of amino-terminated curing agent are added, and stirring is continued at 600 r / min for 15 min to obtain an exterior wall coating. The remaining steps are the same as in Example 2.

[0020] Test Example 1 Anti-aging performance test Test method: The exterior wall coatings of the examples and comparative examples were uniformly applied to asbestos boards and allowed to dry naturally for 48 hours. They were then artificially aged in a xenon arc lamp aging test chamber for 30 days, with a cumulative irradiation energy of 1500 MJ / m². 2 The surface chalking grade was determined using a chalking rate tester according to GB / T 14826-93. The results are shown in Table 1.

[0021] Table 1 ; A comparison of the experimental data from Examples 1-3 and Comparative Examples 1-4 in Table 1 reveals that the building exterior wall coating prepared by the present invention has good anti-aging properties.

[0022] By comparison, the degree of pulverization in Examples 1-3 was lower than that in Comparative Example 1, indicating that a diazonium salt solution was prepared by diazotization reaction of 4-methyl-2-nitroaniline, sulfuric acid aqueous solution, and sodium nitrite aqueous solution; the diazonium salt solution was coupled with 2-vinylphenol to prepare an azo intermediate; the azo intermediate was reduced and cyclized with iron powder and hydrochloric acid to prepare a benzotriazole monomer; the ortho-hydroxy nitrogen heterocycle in the benzotriazole structure transitions from the ground state to the excited state after absorbing high-energy ultraviolet light. The excited state energy is efficiently converted into harmless heat energy and released through the breaking and regeneration cycle of intramolecular hydrogen bonds. The benzotriazole molecule converts ultraviolet light energy into heat energy and dissipates it through the reversible change of its own structure, preventing ultraviolet light energy from directly acting on the resin polymer chain, thus inhibiting the resin chain breakage and free radical oxidation caused by ultraviolet light from the root, thereby endowing the building exterior wall coating with excellent anti-aging properties.

[0023] By comparison, the degree of pulverization in Examples 1-3 was lower than that in Comparative Example 3, indicating that the reaction of cyanuric chloride and 1H,1H-undecylfluorohexylamine yields a primary substituted cyanuric chloride; the reaction of the primary substituted cyanuric chloride and 1H,1H-undecylfluorohexylamine yields a secondary substituted cyanuric chloride, with fluorocarbon links grafted onto the cyanuric chloride; the reaction of the secondary substituted cyanuric chloride and 4-penten-1-amine yields a modified cyanuric chloride monomer; through the modification of cyanuric chloride, a triazine ring structure is introduced into acrylic resin; the triazine ring conjugated system can efficiently absorb ultraviolet light in the 290-400nm wavelength band. After absorbing ultraviolet light, its molecules transition from the ground state to the excited state. The excited state energy is converted into heat energy through rapid and reversible intramolecular proton transfer and electronic reconstruction, thereby effectively "intercepting" and eliminating ultraviolet photons, and further improving the anti-aging performance of building exterior wall coatings.

[0024] Test Example 2 Hydrophobicity test Test method: The exterior wall coatings of the examples and comparative examples were poured into 12×2.5cm molds and cured at room temperature for 4 days. After demolding, they were placed in a constant temperature drying oven at 40℃ for another 2 days. The sample surfaces were wiped clean with degreased cotton, and then the contact angle of water droplets on different sample surfaces was measured using a surface contact angle meter to evaluate their hydrophobic properties. The results are shown in Table 2.

[0025] Table 2 ; A comparison of the experimental data from Examples 1-3 and Comparative Examples 1-4 in Table 2 reveals that the building exterior wall coating prepared by the present invention has good hydrophobic properties.

[0026] By comparison, the contact angles of Examples 1-3 are greater than those of Comparative Examples 2-3, indicating that the reaction of cyanuric chloride and 1H,1H-undecanohexylamine yields a primary substituted cyanuric chloride; the reaction of the primary substituted cyanuric chloride and 1H,1H-undecanohexylamine yields a secondary substituted cyanuric chloride, and fluorocarbon chains are grafted onto the cyanuric chloride; the reaction of the secondary substituted cyanuric chloride and 4-penten-1-amine yields a modified cyanuric chloride monomer; through the modification of cyanuric chloride, fluorocarbon chains are introduced into acrylic resin; fluorocarbon chains have extremely low surface energy, and when this monomer participates in the curing of building exterior wall coatings, these fluorocarbon chains spontaneously migrate to the coating surface and arrange themselves tightly, forming a dense low surface energy barrier, preventing water or common oily contaminants from spreading smoothly on the coating surface, thereby endowing the building exterior wall coating with excellent hydrophobic properties.

[0027] Test Example 3 Flame retardant performance test Test Method: The flame retardancy time test was conducted according to GB / T12441-2018. The exterior wall coatings of the examples and comparative examples were applied to asbestos boards and left to stand for 24 hours, then dried in a drying oven for 2 days. The asbestos boards with the coating were fixed on an iron stand with the coated side facing down, and the torch nozzle was aimed at the center of the asbestos board. An alcohol torch was then used to test the flame retardant performance of the coating, with the nozzle 9 cm from the board. The carbonization time on the back of the asbestos board was recorded to evaluate the flame retardant performance of the exterior wall coating. The results are shown in Table 3.

[0028] Table 3 ; A comparison of the experimental data from Examples 1-3 and Comparative Examples 1-4 in Table 3 reveals that the building exterior wall coating prepared by the present invention has good flame retardant properties.

[0029] By comparison, the back carbonization time of Examples 1-3 was longer than that of Comparative Example 3, indicating that reacting cyanuric chloride with 1H,1H-undecylfluorohexylamine yields a primary substituted cyanuric chloride; reacting the primary substituted cyanuric chloride with 1H,1H-undecylfluorohexylamine yields a secondary substituted cyanuric chloride; and reacting the secondary substituted cyanuric chloride with 4-penten-1-amine yields a modified cyanuric chloride monomer. Through the modification of cyanuric chloride, a triazine ring structure is introduced into acrylic resin. Under high temperature or combustion conditions, the triazine ring structure can rapidly decompose, catalyzing the dehydration and crosslinking of the polymer matrix, forming a dense and stable expanded char layer in the condensed phase, while releasing non-flammable nitrogen and ammonia. These gases not only dilute the concentration of flammable gases and oxygen, but also make the char layer more fluffy and solid through expansion. The expanded char layer can act as a physical barrier to prevent heat and oxygen from being transferred to the building substrate, inhibiting the escape of flammable volatiles, thereby interrupting the combustion cycle and giving the building exterior wall coating excellent flame retardant properties.

[0030] By comparison, the back carbonization time of Examples 1-3 was longer than that of Comparative Example 4, indicating that the polyurethane prepolymer was prepared by reacting isophorone diisocyanate and 2,2-dimethylolpropionic acid; phosphorus-containing diamine was prepared by reacting but-2-ene-1,4-diamine and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide; and amino-terminated phosphorus-containing curing agent was prepared by reacting the polyurethane prepolymer and the phosphorus-containing diamine, thus introducing a DOPO structure into the polyurethane curing agent. When the coating is exposed to a fire source or high temperature, the DOPO structure will decompose first, forming strongly dehydrating substances such as phosphoric acid and metaphosphoric acid. These substances can catalyze the dehydration and carbonization of the polymer matrix and the nitrogen-containing but-2-ene-1,4-diamine and triazine ring components, forming an expanded carbon layer, thereby further improving the flame retardant performance of the building exterior wall coating.

[0031] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A building exterior wall coating, characterized in that, The building exterior wall coating is prepared by reacting azo intermediates, iron powder, and hydrochloric acid to obtain benzotriazole monomer; reacting secondary substituted cyanuric chloride with 4-penten-1-amine to obtain modified cyanuric chloride monomer; reacting polyurethane prepolymer with phosphorus-containing diamine to obtain a phosphorus-containing curing agent; reacting ethyl acrylate, [2-(ethylene oxide-2-yl)ethyl] acrylate, benzotriazole monomer, modified cyanuric chloride monomer, azobisisobutyronitrile, and propylene glycol monomethyl ether acetate to obtain an acrylic resin solution; and preparing the coating by mixing the acrylic resin solution, dispersant, defoamer, silica, calcined stone, wetting agent, leveling agent, thickener, and phosphorus-containing curing agent into a paste. The azo intermediate is prepared by reacting 2-vinylphenol with a diazonium salt solution; The diazonium salt solution is prepared by reacting 4-methyl-2-nitroaniline, an aqueous sulfuric acid solution, and an aqueous sodium nitrite solution. The secondary substituted cyanuric chloride is prepared by reacting a primary substituted cyanuric chloride with 1H,1H-undecylfluorohexylamine. The aforementioned primary substituted cyanuric chloride is prepared by reacting cyanuric chloride with 1H,1H-undecylfluorohexylamine. The polyurethane prepolymer is prepared by reacting isophorone diisocyanate and 2,2-dimethylolpropionic acid. The phosphorus-containing diamine is prepared by reacting but-2-ene-1,4-diamine and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide.

2. A method for preparing an exterior wall coating, characterized in that, The preparation method of the building exterior wall coating includes the following preparation steps: (1) Mix the azo intermediate, iron powder, and 6M hydrochloric acid in a mass ratio of 1:(1~1.2):(5~7) until homogeneous. Stir and reflux at 300~500r / min at 80~100℃ for 4~6h. Cool to room temperature, filter, adjust the pH of the filtrate to 7~8 with saturated sodium hydroxide solution, filter, and dry at 80~100℃ for 8~10h to obtain benzotriazole monomer; (2) Add equimolar amounts of 4-penten-1-amine and saturated sodium hydroxide aqueous solution to the secondary substituted cyanuric chloride, heat to 85~95℃, continue stirring for 7~9h, cool to room temperature, filter, wash 3~5 times with acetone and deionized water respectively, and dry at 60~80℃ for 12~14h to obtain the modified cyanuric chloride monomer. (3) The polyurethane prepolymer, phosphorus-containing diamine, and N,N-dimethylformamide are mixed evenly at a mass ratio of 1:(1~1.2):(8~10). Under nitrogen protection, the mixture is stirred at 500~800 r / min for 2~3 h at room temperature. Deionized water with a mass of 4~5 times that of N,N-dimethylformamide is added, and the mixture is stirred at 800~1000 r / min for 20~30 min. After precipitation, the mixture is filtered, washed 3~5 times with deionized water, and vacuum dried at 40~60℃ for 30~36 h to obtain the phosphorus-containing curing agent. (4) Mix 100-120 parts of acrylic resin solution, 1.6-2 parts of dispersant, and 0.4-0.8 parts of defoamer evenly, stir at 1000-1400 r / min for 10-20 min, add 10-20 parts of silica and 80-100 parts of calcined stone, continue stirring for 30-40 min, add 0.4-0.6 parts of wetting agent, 0.4-0.8 parts of leveling agent, 1.4-1.8 parts of thickener and 20-30 parts of phosphorus-containing curing agent, stir at 500-700 r / min for 10-20 min to obtain building exterior wall coating.

3. The method for preparing building exterior wall coating according to claim 2, characterized in that, The preparation method of the azo intermediate in step (1) is as follows: 2-vinylphenol is dissolved in a 5% sodium carbonate aqueous solution with a mass ratio of 0.4 to 0.6 times that of 4-methyl-2-nitroaniline, stirred at 300 to 500 r / min for 10 to 20 min, cooled to 0 to 4℃, and a diazonium salt solution is added uniformly over 30 to 50 min. The reaction is continued to be stirred for 1 to 2 h, filtered, washed 3 to 5 times with cold deionized water, and dried at 80 to 100℃ for 8 to 10 h to obtain the azo intermediate.

4. The method for preparing building exterior wall coating according to claim 3, characterized in that, The method for preparing the diazonium salt solution is as follows: Weigh 4-methyl-2-nitroaniline, sodium nitrite, and 2-vinylphenol in a molar ratio of 1:1:1; mix 4-methyl-2-nitroaniline and a 20% sulfuric acid aqueous solution in a mass ratio of 1:(8~10) until homogeneous; stir at 0~4℃ and 300~500r / min for 10~20min; add a 20% sodium nitrite aqueous solution at a uniform rate over 30~40min; continue stirring and reacting for 1~2h to obtain the diazonium salt solution.

5. The method for preparing building exterior wall coating according to claim 2, characterized in that, The preparation method of the secondary substituted cyanuric chloride in step (2) is as follows: add 1H,1H-undecylamine and saturated sodium hydroxide aqueous solution in 1H,1H-undecylamine to the primary substituted cyanuric chloride, heat to 45~55℃, and continue stirring for 7~9h to obtain the secondary substituted cyanuric chloride.

6. The method for preparing building exterior wall coating according to claim 5, characterized in that, The preparation method of the primary substituted cyanuric chloride is as follows: cyanuric chloride, 1H,1H-undecylfluorohexylamine and sodium hydroxide are weighed in a molar ratio of 1:1:

1. Cyanuric chloride and acetone are mixed evenly in a mass ratio of 1:(8~10). 1H,1H-undecylfluorohexylamine and saturated sodium hydroxide aqueous solution are added. The mixture is cooled to 0~4℃ and stirred at 300~500r / min for 3~4h to obtain the primary substituted cyanuric chloride.

7. The method for preparing building exterior wall coating according to claim 2, characterized in that, The preparation method of the polyurethane prepolymer in step (3) is as follows: isophorone diisocyanate, 2,2-dimethylolpropionic acid, N,N-dimethylformamide and dibutyltin dilaurate are mixed evenly in a mass ratio of 1:(1.2~1.4):(8~10):(0.02~0.04), heated to 60~70℃ under nitrogen protection, and stirred at 300~500r / min for 5~6h to obtain the polyurethane prepolymer.

8. The method for preparing building exterior wall coating according to claim 2, characterized in that, The preparation method of the phosphorus-containing diamine in step (3) is as follows: but-2-ene-1,4-diamine and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide are mixed evenly at a mass ratio of 1:(2~3), heated to 140~150℃, and stirred at 300~500r / min for 8~10h to obtain the phosphorus-containing diamine.

9. The method for preparing building exterior wall coating according to claim 2, characterized in that, The acrylic resin solution in step (4) is prepared by mixing 25-35 parts of ethyl acrylate, 15-25 parts of [2-(ethylene oxide-2-yl)ethyl] acrylate, 10-14 parts of benzotriazole monomer, 8-10 parts of modified cyanuric chloride monomer, 0.5-1.5 parts of azobisisobutyronitrile and 40-50 parts of propylene glycol monomethyl ether acetate by mass. Under nitrogen protection, the mixture is heated to 80-90°C and stirred at 500-700 r / min for 4-6 h. The mixture is then cooled to room temperature to obtain the acrylic resin solution.