Flame-retardant mesoporous thermal insulation coating and preparation method thereof

Abstract

The invention discloses a flame-retardant mesoporous thermal insulation coating and a preparation method thereof, and relates to the technical field of coatings. The preparation method comprises the following steps: S1, preparing a polyurethane-acrylic emulsion; s2, mixing a mesoporous material, a dispersing agent, absolute ethyl alcohol and deionized water to obtain mesoporous slurry; and S3, preparing melamine modified ammonium polyphosphate. S4, mixing hollow microspheres, ethanol and deionized water, and performing ultrasonic dispersion; and adding the mesoporous slurry, dipentaerythritol, melamine, melamine modified ammonium polyphosphate and a dispersing agent, grinding, adding a polyurethane-acrylic emulsion and an auxiliary agent, and dispersing at a medium speed to obtain the flame-retardant mesoporous thermal insulation coating. The components are designed and optimized, so that a coating formed after the prepared flame-retardant mesoporous thermal insulation coating is cured has excellent flame retardance, thermal insulation property and mechanical property.

Description

Technical Field

[0001] The present invention relates to the technical field of coatings, in particular to a flame-retardant mesoporous thermal insulation coating and a preparation method thereof. Background Art

[0002] Heat-resistant, flame-retardant mesoporous thermal insulation coatings are a new type of functional coating that combines the unique structural properties and high-temperature stability of mesoporous materials. They are widely used in the petrochemical industry, power equipment, building fire protection, aerospace, and other fields. Mesoporous materials (such as mesoporous silica), due to their high specific surface area and controllable pore structure with a pore size distribution ranging from 2-50 nm, effectively reduce heat transfer by conduction and convection, thereby improving the thermal insulation performance of the coating, making them an ideal substrate for the next generation of lightweight, high-efficiency thermal insulation coatings.

[0003] While there are a wide variety of thermal insulation and flame-retardant coatings currently available on the market, most struggle to balance thermal insulation and flame-retardant properties. Most thermal insulation coatings are flammable, while most flame-retardant coatings lack thermal insulation. While traditional insulation materials (such as rock wool and calcium silicate boards) offer thermal insulation properties, they suffer from high bulk density, poor construction flexibility, susceptibility to moisture absorption and aging, and flammability. Most existing flame-retardant thermal insulation coatings on the market suffer from insufficient structural stability, poor environmental adaptability, and complex construction processes, significantly limiting their scope of application. Furthermore, widely used phosphorus-based flame retardants offer the advantages of being environmentally friendly and having excellent flame-retardant properties. However, the ammonium polyphosphate that makes up these flame-retardant coatings is extremely hygroscopic, disrupting the overall balance of the coating and accelerating its pulverization, making them difficult to apply effectively.

[0004] In summary, in order to solve the above problems, it is of great significance to prepare a flame retardant mesoporous thermal insulation coating. Summary of the Invention

[0005] The object of the present invention is to provide a flame retardant mesoporous thermal insulation coating and a preparation method thereof, so as to solve the problems raised in the above background technology.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions: A method for preparing a flame-retardant mesoporous thermal insulation coating comprises the following steps: S1: (1) Methyl methacrylate, butyl acrylate, acrylic acid, and ammonium persulfate were mixed to obtain solution A; (2) Solution A was added dropwise to the polyurethane dispersion, the temperature was controlled at 75-80°C, free radical polymerization was carried out for 4-5 hours, vacuum distillation was performed, the pH was adjusted to 7-8, and the solution was filtered to obtain a polyurethane-acrylic emulsion; S2: mixing the mesoporous material, dispersant, anhydrous ethanol and deionized water to obtain a mesoporous slurry; S3: (1) ammonium polyphosphate and deionized water are mixed and ultrasonically dispersed to obtain suspension B; (2) melamine-formaldehyde resin prepolymer is slowly added dropwise to suspension B, the temperature is controlled at 70-80°C, and after reacting for 2-3 hours, the mixture is cooled, filtered, washed 3-5 times, and vacuum dried to obtain melamine-modified ammonium polyphosphate; S4: hollow microspheres, ethanol, and deionized water are mixed and ultrasonically dispersed; mesoporous slurry, dipentaerythritol, melamine, melamine-modified ammonium polyphosphate, and a dispersant are added, and the mixture is ground; polyurethane-acrylic emulsion and additives are added, and the mixture is dispersed at a medium speed to obtain a flame-retardant mesoporous thermal insulation coating.

[0007] More optimally, the flame-retardant mesoporous thermal insulation coating includes the following raw materials in parts by weight: 1 to 5 parts of hollow microspheres, 1 to 10 parts of ethanol, 1 to 10 parts of deionized water, 1 to 5 parts of mesoporous slurry, 5 to 15 parts of dipentaerythritol, 5 to 15 parts of melamine, 10 to 30 parts of melamine-modified ammonium polyphosphate, 1 to 5 parts of dispersant, 20 to 30 parts of polyurethane-acrylic emulsion, and 3 to 7 parts of additives; the additives include one or more of film-forming additives, defoaming agents, anti-settling agents, leveling agents, wetting agents, and pH regulators.

[0008] More optimally, the solution A comprises the following raw materials in parts by weight: 10-15 parts of methyl methacrylate, 10-15 parts of butyl acrylate, 2-3 parts of acrylic acid, and 0.5-1 part of ammonium persulfate; the polyurethane-acrylic emulsion comprises the following raw materials in parts by weight: 5-10 parts of solution A and 12-18 parts of polyurethane dispersion; the mesoporous slurry comprises the following raw materials in parts by weight: 5-10 parts of mesoporous material, 1-3 parts of dispersant, 10-15 parts of anhydrous ethanol, and 15-25 parts of deionized water; The suspension B comprises the following raw materials in parts by weight: 10-15 parts of ammonium polyphosphate and 30-50 parts of deionized water; the melamine-modified ammonium polyphosphate comprises the following raw materials in parts by weight: 6-15 parts of melamine-formaldehyde resin prepolymer and 40-60 parts of suspension B.

[0009] More optimally, the mesoporous material is hollow silica microspheres, and the preparation method is as follows: the mesoporous material is hollow silica microspheres, and the preparation method is as follows: nitric acid and phenyltrimethoxysilane are mixed, the temperature is raised to 58~62℃ and kept in a water bath for 3~5min, ammonia water is added, stirred for 1~2h, centrifuged, washed, and dried, the temperature is raised to 190~210℃ and kept warm for 1~2h, and then the temperature is raised to 640~670℃ and calcined for 15~17h to obtain hollow mesoporous silica nanospheres; wherein the mass ratio of nitric acid, phenyltrimethoxysilane, and ammonia water is 1:10:5.

[0010] More optimally, the preparation method of the melamine-modified ammonium polyphosphate is as follows: deionized water is added to a reactor, the temperature is raised to 60-70°C, melamine and formaldehyde solutions are added, the mixture is stirred and dissolved, the pH is adjusted to 8-9 with aqueous ammonia, and the mixture is kept warm for 1-2 hours to obtain a melamine-formaldehyde resin prepolymer.

[0011] More optimally, the preparation method of the polyurethane dispersion is as follows: under nitrogen protection, polyether polyol, isophorone diisocyanate and dibutyltin dilaurate are added to a reactor, the temperature is raised to 70-80°C and the reaction is carried out for 2-3 hours, dimethylolpropionic acid and acetone are added, the reaction is continued until the isocyanate group content meets the standard, the temperature is lowered to 35-40°C, triethylamine is added for neutralization, and the mixture is stirred for 30-50 minutes. Deionized water is slowly added, and high-speed shear emulsification is performed at 1000-2000 rpm to obtain a polyurethane dispersion; wherein the mass ratio of polyether polyol, isophorone diisocyanate, dibutyltin dilaurate, dimethylolpropionic acid, acetone and triethylamine is 100:20-25:0.1:6:40:3-6; and the solid content of the polyurethane dispersion is 55-60%.

[0012] More optimally, the polyether polyol comprises polytetrahydrofuran polyol and phenyl-containing polyol in a mass ratio of 6-7:3-4.

[0013] More optimally, the preparation method of the phenyl-containing polyol is as follows: (1) adding 1,4-phenylenediboronic acid and 1-thioglycerol to tetrahydrofuran, adding magnesium sulfate as a desiccant, stirring at room temperature for 24 hours, filtering to remove the magnesium sulfate as a desiccant, distilling under reduced pressure to remove the solvent, washing, and drying to obtain dimercaptophenyl borate; (2) adding allyl carbinol, dimercaptophenyl borate, and a photoinitiator to tetrahydrofuran in sequence, reacting under ultraviolet light for 2 to 4 hours to obtain the phenyl-containing polyol; In the raw material of the dimercaptophenyl borate, the mass ratio of 1,4-phenylenediboronic acid to 1-thioglycerol ester is 1.5:2-2.2; In the raw material containing phenyl polyol, the mass ratio of allyl carbinol to dimercaptophenyl borate is 2.5:1.4-1.5.

[0014] More optimally, the dispersant is a modified silane coupling agent, and the preparation method is as follows: (1) adding 3-vinylphenylboronic acid and glycerol to tetrahydrofuran, adding magnesium sulfate desiccant, stirring at room temperature for 24 hours, filtering to remove the magnesium sulfate desiccant, distilling under reduced pressure to remove the solvent, washing, and drying to obtain vinylbenzene borate; (1) adding vinylbenzene borate, γ-methacryloyloxypropyltrimethoxysilane, and a photoinitiator to tetrahydrofuran, reacting under ultraviolet light for 2 to 4 hours to obtain a modified silane coupling agent; In the raw materials of the alkenylphenyl borate, the mass ratio of 3-vinylphenylboric acid to glycerol is 1.5:0.95~1; in the raw materials of the modified silane coupling agent, the mass ratio of alkenylphenyl borate to γ-methacryloxypropyltrimethoxysilane is 1:1.

[0015] More optimally, a flame retardant mesoporous thermal insulation coating is prepared by a method for preparing a flame retardant mesoporous thermal insulation coating.

[0016] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention provides a heat-resistant and flame-retardant mesoporous thermal insulation coating and a preparation method thereof. The components thereof are designed and optimized, and the prepared coating forms a coating having low thermal conductivity, high flame retardancy, high stability and high adhesion after curing.

[0017] (2) The present invention adopts an innovative composite flame retardant system, using melamine resin-coated modified ammonium polyphosphate as the core flame retardant, achieving uniform coating through an in-situ polymerization process, and combining melamine and dipentaerythritol to form an intumescent flame retardant system. During combustion, a dense carbon layer is formed, effectively improving the flame retardant properties of the coating. At the same time, the introduction of mesoporous slurry improves the thermal resistance effect of the coating. Its unique multi-level pore structure and high specific surface area effectively reduce the thermal conductivity coefficient. The preparation of a specific segment polyurethane-acrylic emulsion and the definition of the dispersant further improve the thermal insulation performance.

[0018] Among them, hollow mesoporous silica nanospheres prepared by a special process were used as thermal insulation materials. By optimizing the dispersion process, the mesoporous material was evenly distributed in the coating, constructing a multi-level thermal insulation system and reducing the thermal conductivity of the coating.

[0019] The polyurethane-acrylic composite emulsion used provides excellent film-forming and mechanical properties, resulting in a coating with both high elasticity and strong adhesion. The solution further incorporates a benzene-containing polyol and a dispersant (modified silane coupling agent) containing phenylborane groups to further enhance thermal insulation, mechanical properties, and flame retardancy. Firstly, the molecular structure of the phenylborane group contains a benzene ring and a BO bond. The rigid structure of the benzene ring reduces molecular chain vibration, while the polarity of the BO bond can scatter phonons (the primary heat carrier), thereby reducing heat conduction. The resulting dynamic covalent network further hinders heat transfer. Secondly, the phenylborane group generates boroxy radicals during thermal decomposition of phenylborane ester, which quench highly reactive free radicals such as H• and OH• in the flame, interrupting the combustion chain reaction and promoting dehydration to form a carbon, resulting in a dense boron-carbon composite layer that isolates heat and oxygen, thereby enhancing flame retardancy. Thirdly, the phenylborane group enhances molecular cohesion, thereby improving mechanical properties such as adhesion strength. DETAILED DESCRIPTION

[0020] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0021] It should be noted that, in the following embodiments, parts are by weight, and all raw materials involved, unless otherwise specified, are commercially available, without any special restrictions on the purchase manufacturer. Examples thereof include: hollow microspheres of model HS-G; the additives are BYK-329 defoaming agent, BYK-LPG26034 surface additive, RHEOBYK-7600 thickener, BYK-4510 adhesion promoter, and BYK-9076 dispersant in a mass ratio of 1:1:1:1:1.

[0022] Example 1: A method for preparing a flame-retardant mesoporous thermal insulation coating, comprising the following steps: S1: Under nitrogen protection, polyether polyol, isophorone diisocyanate, and dibutyltin dilaurate were added to a reactor, the temperature was raised to 70°C and the reaction was carried out for 2 hours. Dimethylolpropionic acid and a small amount of acetone were added and the reaction was continued until the isocyanate group content reached the standard. The temperature was lowered to 40°C, triethylamine was added for neutralization, and the mixture was stirred for 30 minutes. Deionized water was slowly added and the mixture was emulsified at a high shear speed of 1000 rpm to obtain a polyurethane dispersion with a solid content of 58 wt%; The raw material composition of the polyurethane dispersion is: 100 parts of polyether polyol, 24 parts of isophorone diisocyanate, 0.1 parts of dibutyltin dilaurate, 6 parts of dimethylolpropionic acid, 40 parts of acetone, and 4 parts of triethylamine; the polyether polyol is polytetramethylene glycol polyol PTMG-650; Methyl methacrylate, butyl acrylate, acrylic acid, and ammonium persulfate were mixed to obtain solution A; the raw material composition of solution A was: 12 parts of methyl methacrylate, 10 parts of butyl acrylate, 2 parts of acrylic acid, and 0.5 parts of ammonium persulfate; Solution A was added dropwise to the polyurethane dispersion, the temperature was controlled at 75°C, and a free radical polymerization reaction was carried out for 4 hours. Acetone was removed by distillation under reduced pressure, the pH was adjusted to 7, and the mixture was filtered to obtain a stable polyurethane-acrylic emulsion. The raw material composition of the polyurethane-acrylic emulsion was: 16 parts of polyurethane dispersion and 7 parts of solution A. S2: nitric acid and phenyltrimethoxysilane were mixed, heated to 58°C and kept in a water bath for 3 minutes, ammonia water was added, stirred for 1 hour, centrifuged, washed, dried, heated to 200°C and kept for 2 hours, and then heated to 660°C and calcined for 16 hours to obtain hollow mesoporous silica nanospheres, which were used as mesoporous materials; the raw material composition of the mesoporous material was: nitric acid, phenyltrimethoxysilane, and ammonia water in a mass ratio of 1:10:5; The mesoporous material, dispersant, anhydrous ethanol and deionized water are mixed to obtain a mesoporous slurry; the raw material composition of the mesoporous slurry is: 5 parts of mesoporous material, 2 parts of dispersant, 11 parts of anhydrous ethanol and 15 parts of deionized water; S3: ammonium polyphosphate and deionized water were mixed and ultrasonically dispersed for 30 minutes to obtain suspension B; the raw material composition of the suspension B was: 10 parts of ammonium polyphosphate and 30 parts of deionized water; Melamine-formaldehyde resin prepolymer was slowly added dropwise to suspension B, the temperature was controlled at 70°C, and the mixture was reacted for 2 hours. The mixture was then cooled, filtered, washed 3 times, and vacuum dried at 80°C for 12 hours to obtain melamine-modified ammonium polyphosphate. The raw material composition of the melamine-modified ammonium polyphosphate was: 6 parts of melamine-formaldehyde resin prepolymer and 40 parts of solution B. S4: mixing hollow microspheres, ethanol, and deionized water, and ultrasonically dispersing the mixture; adding mesoporous slurry, dipentaerythritol, melamine, melamine-modified ammonium polyphosphate, and a dispersant, and grinding the mixture; adding polyurethane-acrylic emulsion and additives, and dispersing the mixture at a medium speed to obtain a flame-retardant mesoporous thermal insulation coating; The raw material composition of the thermal insulation coating is: 2 parts of hollow microspheres, 3 parts of ethanol, 7 parts of deionized water, 2 parts of mesoporous slurry, 5 parts of dipentaerythritol, 8 parts of melamine, 15 parts of melamine-modified coated ammonium polyphosphate, 1 part of dispersant, 20 parts of polyurethane-acrylic emulsion, and 3 parts of auxiliary agent; the dispersant is γ-methacryloxypropyltrimethoxysilane.

[0023] Example 2: A method for preparing a flame-retardant mesoporous thermal insulation coating, comprising the following steps: S1: Under nitrogen protection, polyether polyol, isophorone diisocyanate, and dibutyltin dilaurate were added to a reactor, the temperature was raised to 75°C and the reaction was carried out for 2 hours. Dimethylolpropionic acid and a small amount of acetone were added and the reaction was continued until the isocyanate group content reached the standard. The temperature was lowered to 40°C, triethylamine was added for neutralization, and the mixture was stirred for 45 minutes. Deionized water was slowly added and high-speed shear emulsification was performed at 1500 rpm to obtain a polyurethane dispersion with a solid content of 58 wt%; The raw material composition of the polyurethane dispersion is: 100 parts of polyether polyol, 24 parts of isophorone diisocyanate, 0.1 parts of dibutyltin dilaurate, 6 parts of dimethylolpropionic acid, 40 parts of acetone, and 4 parts of triethylamine; the polyether polyol is polytetramethylene glycol polyol PTMG-650; Methyl methacrylate, butyl acrylate, acrylic acid, and ammonium persulfate were mixed to obtain solution A; the raw material composition of solution A was: 10 parts of methyl methacrylate, 15 parts of butyl acrylate, 2.5 parts of acrylic acid, and 1 part of ammonium persulfate; Solution A was added dropwise to the polyurethane dispersion, the temperature was controlled at 75°C, and a free radical polymerization reaction was carried out for 4 hours. Acetone was removed by distillation under reduced pressure, the pH was adjusted to 7, and the mixture was filtered to obtain a stable polyurethane-acrylic emulsion. The raw material composition of the polyurethane-acrylic emulsion was: 12 parts of polyurethane dispersion and 10 parts of solution A. S2: nitric acid and phenyltrimethoxysilane were mixed, heated to 58°C and kept in a water bath for 3 minutes, ammonia water was added, stirred for 1 hour, centrifuged, washed, dried, heated to 200°C and kept for 2 hours, and then heated to 660°C and calcined for 16 hours to obtain hollow mesoporous silica nanospheres, which were used as mesoporous materials; the raw material composition of the mesoporous material was: nitric acid, phenyltrimethoxysilane, and ammonia water in a mass ratio of 1:10:5; The mesoporous material, dispersant, anhydrous ethanol and deionized water are mixed to obtain a mesoporous slurry; the raw material composition of the mesoporous slurry is: 6 parts of mesoporous material, 1 part of dispersant, 13 parts of anhydrous ethanol and 17 parts of deionized water; S3: ammonium polyphosphate and deionized water were mixed and ultrasonically dispersed for 30 minutes to obtain suspension B; the raw material composition of the suspension B was: 15 parts of ammonium polyphosphate and 45 parts of deionized water; Slowly add the melamine-formaldehyde resin prepolymer dropwise to the suspension B, control the temperature at 70°C, react for 2 hours, cool, filter, wash three times, and vacuum dry at 80°C for 12 hours to obtain melamine-modified ammonium polyphosphate; the raw material composition of the melamine-modified ammonium polyphosphate is: 10 parts of melamine-formaldehyde resin prepolymer and 50 parts of solution B; S4: mixing hollow microspheres, ethanol, and deionized water, and ultrasonically dispersing the mixture; adding mesoporous slurry, dipentaerythritol, melamine, melamine-modified ammonium polyphosphate, and a dispersant, and grinding the mixture; adding polyurethane-acrylic emulsion and additives, and dispersing the mixture at a medium speed to obtain a flame-retardant mesoporous thermal insulation coating; The raw material composition of the thermal insulation coating is: 1 part of hollow microspheres, 2 parts of ethanol, 5 parts of deionized water, 5 parts of mesoporous slurry, 7 parts of dipentaerythritol, 5 parts of melamine, 20 parts of melamine-modified coated ammonium polyphosphate, 3 parts of dispersant, 25 parts of polyurethane-acrylic emulsion, and 4 parts of auxiliary agent; the dispersant is γ-methacryloxypropyltrimethoxysilane.

[0024] Example 3: A method for preparing a flame-retardant mesoporous thermal insulation coating, comprising the following steps: S1: Under nitrogen protection, polyether polyol, isophorone diisocyanate, and dibutyltin dilaurate were added to a reactor, the temperature was raised to 80°C and the reaction was carried out for 2 hours. Dimethylolpropionic acid and a small amount of acetone were added and the reaction was continued until the isocyanate group content reached the standard. The temperature was lowered to 35°C, triethylamine was added for neutralization, and the mixture was stirred for 30 minutes. Deionized water was slowly added and high-speed shear emulsification was performed at 2000 rpm to obtain a polyurethane dispersion with a solid content of 58 wt%; The raw material composition of the polyurethane dispersion is: 100 parts of polyether polyol, 24 parts of isophorone diisocyanate, 0.1 parts of dibutyltin dilaurate, 6 parts of dimethylolpropionic acid, 40 parts of acetone, and 4 parts of triethylamine; the polyether polyol is polytetramethylene glycol polyol PTMG-650; Methyl methacrylate, butyl acrylate, acrylic acid, and ammonium persulfate were mixed to obtain solution A; the raw material composition of solution A was: 15 parts of methyl methacrylate, 13 parts of butyl acrylate, 3 parts of acrylic acid, and 0.75 parts of ammonium persulfate; Solution A was added dropwise to the polyurethane dispersion, the temperature was controlled at 75°C, and a free radical polymerization reaction was carried out for 4 hours. Acetone was removed by distillation under reduced pressure, the pH was adjusted to 7, and the mixture was filtered to obtain a stable polyurethane-acrylic emulsion. The raw material composition of the polyurethane-acrylic emulsion was: 18 parts of polyurethane dispersion and 9 parts of solution A. S2: nitric acid and phenyltrimethoxysilane were mixed, heated to 58°C and kept in a water bath for 3 minutes, ammonia water was added, stirred for 1 hour, centrifuged, washed, dried, heated to 200°C and kept for 2 hours, and then heated to 660°C and calcined for 16 hours to obtain hollow mesoporous silica nanospheres, which were used as mesoporous materials; the raw material composition of the mesoporous material was: nitric acid, phenyltrimethoxysilane, and ammonia water in a mass ratio of 1:10:5; The mesoporous material, dispersant, anhydrous ethanol and deionized water are mixed to obtain a mesoporous slurry; the raw material composition of the mesoporous slurry is: 10 parts of mesoporous material, 3 parts of dispersant, 15 parts of anhydrous ethanol and 20 parts of deionized water; S3: ammonium polyphosphate and deionized water were mixed and ultrasonically dispersed for 30 minutes to obtain a suspension B; the raw material composition of the suspension B was: 12 parts of ammonium polyphosphate and 50 parts of deionized water, calculated by weight; Melamine-formaldehyde resin prepolymer was slowly added dropwise to suspension B, the temperature was controlled at 70°C, and the mixture was reacted for 2 hours. The mixture was then cooled, filtered, washed three times, and vacuum dried at 80°C for 12 hours to obtain melamine-modified ammonium polyphosphate. The raw material composition of the melamine-modified ammonium polyphosphate was: 15 parts of melamine-formaldehyde resin prepolymer and 60 parts of solution B. S4: mixing hollow microspheres, ethanol, and deionized water, and ultrasonically dispersing the mixture; adding mesoporous slurry, dipentaerythritol, melamine, melamine-modified ammonium polyphosphate, and a dispersant, and grinding the mixture; adding polyurethane-acrylic emulsion and additives, and dispersing the mixture at a medium speed to obtain a flame-retardant mesoporous thermal insulation coating; The raw material composition of the thermal insulation coating is: 3 parts of hollow microspheres, 7 parts of ethanol, 6 parts of deionized water, 3 parts of mesoporous slurry, 10 parts of dipentaerythritol, 10 parts of melamine, 25 parts of melamine-modified coated ammonium polyphosphate, 5 parts of dispersant, 30 parts of polyurethane-acrylic emulsion, and 6 parts of auxiliary agent; the dispersant is γ-methacryloxypropyltrimethoxysilane.

[0025] Comparative Example 1: Example 3 is used as the control group, except that the melamine-modified coated ammonium polyphosphate is replaced by ammonium polyphosphate, and the other parts are normal.

[0026] Comparative Example 2: Example 3 is used as the control group, except that the mesoporous slurry is removed and the other parts are normal.

[0027] Example 4: Example 3 is used as a control group, except that the preparation of the polyurethane dispersion is adjusted; other parts are normal; the adjusted parts are as follows: In this embodiment, the polyurethane dispersion preparation raw materials include a polyether polyol composed of polytetrahydrofuran polyol PTMG-650 and a phenyl-containing polyol in a mass ratio of 6.5:3.5. The preparation method of the phenyl-containing polyol is as follows: 1,4-phenylenediboric acid and 1-thioglyceride in a mass ratio of 1.5:2.1 are added to tetrahydrofuran, magnesium sulfate is added as a desiccant, and the mixture is stirred at room temperature for 24 hours. The magnesium sulfate desiccant is removed by filtration, the solvent is removed by distillation under reduced pressure, and the mixture is washed and dried to obtain dimercaptophenyl borate; allyl methanol, dimercaptophenyl borate, and photoinitiator 784 are added to tetrahydrofuran in a mass ratio of 2.5:1.5:0.1, and the mixture is reacted under ultraviolet light for 2 hours to obtain the phenyl-containing polyol.

[0028] Example 5: Example 3 is used as a control group, except that the preparation of the polyurethane dispersion and the dispersant are adjusted; other parts are normal; the adjusted parts are as follows: In this embodiment, the polyurethane dispersion preparation raw materials include a polyether polyol composed of polytetrahydrofuran polyol PTMG-650 and a phenyl-containing polyol in a mass ratio of 6.5:3.5. The preparation method of the phenyl-containing polyol is as follows: 1,4-phenylenediboric acid and 1-thioglyceride in a mass ratio of 1.5:2.1 are added to tetrahydrofuran, magnesium sulfate is added as a desiccant, and the mixture is stirred at room temperature for 24 hours. The magnesium sulfate desiccant is removed by filtration, the solvent is removed by distillation under reduced pressure, and the mixture is washed and dried to obtain dimercaptophenyl borate; allyl carbinol, dimercaptophenyl borate, and photoinitiator 784 are added to tetrahydrofuran in a mass ratio of 2.5:1.5:0.1, and the mixture is reacted under ultraviolet light for 2 hours to obtain the phenyl-containing polyol. The dispersant is a modified silane coupling agent, and the preparation method is as follows: (1) adding 3-vinylphenylboric acid and glycerol in a mass ratio of 1.5:0.95~1 to tetrahydrofuran, adding magnesium sulfate desiccant, stirring at room temperature for 24 hours, filtering to remove the magnesium sulfate desiccant, distilling under reduced pressure to remove the solvent, washing and drying to obtain vinylbenzene borate; (1) adding vinylbenzene borate, γ-methacryloyloxypropyltrimethoxysilane and photoinitiator in a mass ratio of 1:1:0.05 to tetrahydrofuran, reacting under ultraviolet light for 2~4 hours to obtain a modified silane coupling agent.

[0029] Comparative Example 3: Example 5 is used as the control group, except that the polyether polyol is composed of polytetramethylene glycol PTMG-650 and phenyl-containing polyol in a mass ratio of 3.5:6.5; the other parts are normal.

[0030] Performance Test 1: The flame-retardant mesoporous thermal insulation coating obtained in Examples 1 to 5 was used as a substrate on a 100mm×150mm×3mm steel plate. After coating and curing, a 5mm thick coating was formed, and relevant performance tests were performed; (1) Flame retardancy test: The flame retardancy grade was tested in accordance with GB8624-2012; (2) Salt spray resistance test: A 1000h salt spray test was performed in accordance with GB / T1771-2007, and the coating was observed to see if any abnormalities occurred after the test. (3) Aging resistance test: A 500h xenon lamp aging test was performed in accordance with GB / T1865-2009, and the coating was observed to see if any abnormalities occurred after the test. The results are shown in Table 1: Table 1:

[0031] Performance Test 2: The flame-retardant mesoporous thermal insulation coatings obtained in Examples 1 to 5 and Comparative Examples 1 to 3 were used as substrates on a 100 mm × 150 mm × 3 mm steel plate. (1) After coating and curing, a 1 mm thick coating was formed. A pull-out test was performed according to the standard of GB / T 5210 to obtain adhesion. (2) After coating and curing, a 5 mm thick coating was formed. The thermal insulation properties of the coating were tested at temperatures of 80°C, 120°C, and 160°C. The results are shown in Table 2: Table 2:

[0032] Conclusion: The data in Table 1 demonstrate that this application has produced a flame-retardant mesoporous thermal insulation coating with excellent flame retardancy and stability. By encapsulating ammonium polyphosphate with melamine, the coating's flame retardancy is enhanced while simultaneously avoiding the negative impact of the unmodified ammonium polyphosphate's strong hygroscopicity on coating stability, ensuring that the coating maintains stable flame retardancy in various environments. The coating exhibited no abnormalities in salt spray and aging resistance tests, demonstrating its excellent long-term durability. It can be widely used in fire protection and thermal insulation applications in buildings, industrial equipment, and other fields, possessing significant engineering value.

[0033] The data in Table 2 show that the present application effectively ensures adhesion through component optimization and preparation method definition; at the same time, the thermal resistance effect of the coating is improved by the introduction of mesoporous slurry, and its unique multi-level pore structure and high specific surface area effectively reduce the thermal conductivity coefficient. In addition, by preparing a specific segment polyurethane-acrylic emulsion and defining the dispersant, the coating exhibits excellent thermal insulation performance in thermal environment tests at 80°C, 120°C, and 160°C.

[0034] In Comparative Example 1, when ammonium polyphosphate is used in the preparation of thermal insulation coating, since ammonium polyphosphate that has not been modified and coated with melamine has strong hygroscopicity, its addition will destroy the balance and stability between the coating systems, cause stress concentration in the coating film, and ultimately cause shrinkage and cracking of the coating, resulting in a decline in related performance.

[0035] In Comparative Example 2, the coating's unique pore size distribution, high specific surface area, and multi-level pore structure significantly enhance its thermal resistance, thereby improving its thermal insulation performance. However, after removing the mesoporous slurry, performance testing revealed an increase in the coating's thermal conductivity and heat flux, resulting in a significant decrease in its thermal insulation performance compared to Example 3.

[0036] In Example 4, which is a further solution based on Example 3, phenylboron-containing groups are further introduced into the polyurethane dispersion, so that a thermal insulation network is generated in the cross-linked network of the coating, and the thermal insulation is synergistically improved with the mesoporous coating.

[0037] Example 5 is a further solution of Example 3. In addition to adjusting the polyether polyol of the polyurethane dispersion, a modified coupling agent containing similar groups is further introduced to further improve the compatibility of the mesoporous material and enhance the thermal insulation.

[0038] In Comparative Example 3, it can be found that when too much phenyl-containing polyol is introduced into the polyether polyol of the polyurethane dispersion, the thermal insulation property is not improved, but the balance and stability between the coating systems are destroyed, resulting in a decrease in related performance.

[0039] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for preparing a flame-retardant mesoporous thermal insulation coating, characterized in that: The following steps are involved: S1: (1) Methyl methacrylate, butyl acrylate, acrylic acid, and ammonium persulfate were mixed to obtain solution A; (2) Solution A was added dropwise to the polyurethane dispersion, the temperature was controlled at 75-80°C, free radical polymerization was carried out for 4-5 hours, vacuum distillation was performed, the pH was adjusted to 7-8, and the solution was filtered to obtain a polyurethane-acrylic emulsion; S2: mixing the mesoporous material, dispersant, anhydrous ethanol and deionized water to obtain a mesoporous slurry; S3: (1) ammonium polyphosphate and deionized water are mixed and ultrasonically dispersed to obtain suspension B; (2) melamine-formaldehyde resin prepolymer is slowly added dropwise to suspension B, the temperature is controlled at 70-80°C, and after reacting for 2-3 hours, the mixture is cooled, filtered, washed 3-5 times, and vacuum dried to obtain melamine-modified ammonium polyphosphate; S4: hollow microspheres, ethanol, and deionized water are mixed and ultrasonically dispersed; mesoporous slurry, dipentaerythritol, melamine, melamine-modified ammonium polyphosphate, and a dispersant are added, and the mixture is ground; polyurethane-acrylic emulsion and additives are added, and the mixture is dispersed at a medium speed to obtain a flame-retardant mesoporous thermal insulation coating.

2. The method for preparing a flame-retardant mesoporous thermal insulation coating according to claim 1, characterized in that: The flame-retardant mesoporous thermal insulation coating includes the following raw materials in parts by weight: 1 to 5 parts of hollow microspheres, 1 to 10 parts of ethanol, 1 to 10 parts of deionized water, 1 to 5 parts of mesoporous slurry, 5 to 15 parts of dipentaerythritol, 5 to 15 parts of melamine, 10 to 30 parts of melamine-modified ammonium polyphosphate, 1 to 5 parts of dispersant, 20 to 30 parts of polyurethane-acrylic emulsion, and 3 to 7 parts of additives; the additives include one or more of a film-forming aid, a defoaming agent, an anti-settling agent, a leveling agent, a wetting agent, and a pH regulator.

3. The method for preparing a flame-retardant mesoporous thermal insulation coating according to claim 1, characterized in that: The solution A comprises the following raw materials in parts by weight: 10-15 parts of methyl methacrylate, 10-15 parts of butyl acrylate, 2-3 parts of acrylic acid, and 0.5-1 part of ammonium persulfate; the polyurethane-acrylic emulsion comprises the following raw materials in parts by weight: 5-10 parts of solution A and 12-18 parts of polyurethane dispersion; the mesoporous slurry comprises the following raw materials in parts by weight: 5-10 parts of mesoporous material, 1-3 parts of dispersant, 10-15 parts of anhydrous ethanol, and 15-25 parts of deionized water; The suspension B comprises the following raw materials in parts by weight: 10-15 parts of ammonium polyphosphate and 30-50 parts of deionized water; the melamine-modified ammonium polyphosphate comprises the following raw materials in parts by weight: 6-15 parts of melamine-formaldehyde resin prepolymer and 40-60 parts of suspension B.

4. The method for preparing a flame-retardant mesoporous thermal insulation coating according to claim 1, characterized in that: The mesoporous material is hollow silica microspheres, and the preparation method is as follows: nitric acid and phenyltrimethoxysilane are mixed, heated to 58-62° C. and kept in a water bath for 3-5 minutes, ammonia water is added, stirred for 1-2 hours, centrifuged, washed, and dried, heated to 190-210° C. and kept heated for 1-2 hours, and then heated to 640-670° C. and calcined for 15-17 hours to obtain hollow mesoporous silica nanospheres; wherein the mass ratio of nitric acid, phenyltrimethoxysilane, and ammonia water is 1:10:

5.

5. The method for preparing a flame-retardant mesoporous thermal insulation coating according to claim 1, characterized in that: The preparation method of the melamine-modified ammonium polyphosphate comprises the following steps: adding deionized water into a reaction kettle, heating the kettle to 60-70° C., adding melamine and formaldehyde solutions, stirring and dissolving the mixture, adjusting the pH to 8-9 with aqueous ammonia, and reacting the mixture at the temperature for 1-2 hours to obtain a melamine-formaldehyde resin prepolymer.

6. The method for preparing a flame-retardant mesoporous thermal insulation coating according to claim 1, characterized in that: The preparation method of the polyurethane dispersion comprises the following steps: under nitrogen protection, adding polyether polyol, isophorone diisocyanate and dibutyltin dilaurate into a reaction kettle, heating the mixture to 70-80°C and reacting for 2-3 hours, adding dimethylolpropionic acid and acetone, continuing the reaction until the isocyanate group content reaches a standard, cooling the mixture to 35-40°C, adding triethylamine for neutralization, stirring the mixture for 30-50 minutes, slowly adding deionized water, and emulsifying the mixture at a high shear speed of 1000-2000 rpm to obtain the polyurethane dispersion. The mass ratio of the polyether polyol, isophorone diisocyanate, dibutyltin dilaurate, dimethylolpropionic acid, acetone and triethylamine is 100:20-25:0.1:6:40:3-6, and the solid content of the polyurethane dispersion is 55-60%.

7. The method for preparing a flame-retardant mesoporous thermal insulation coating according to claim 6, characterized in that: The polyether polyol comprises polytetrahydrofuran polyol and phenyl-containing polyol in a mass ratio of 6-7:3-4.

8. The method for preparing a flame-retardant mesoporous thermal insulation coating according to claim 7, characterized in that: The preparation method of the phenyl-containing polyol is as follows: (1) adding 1,4-phenylenediboronic acid and 1-thioglycerol to tetrahydrofuran, adding magnesium sulfate as a desiccant, stirring at room temperature for 24 hours, filtering to remove the magnesium sulfate as a desiccant, distilling under reduced pressure to remove the solvent, washing, and drying to obtain dimercaptophenyl borate; (2) adding allyl carbinol, dimercaptophenyl borate, and a photoinitiator to tetrahydrofuran in sequence, reacting under ultraviolet light for 2 to 4 hours, and obtaining the phenyl-containing polyol; In the raw material of the dimercaptophenyl borate, the mass ratio of 1,4-phenylenediboronic acid to 1-thioglycerol ester is 1.5:2-2.2; In the raw material containing phenyl polyol, the mass ratio of allyl carbinol to dimercaptophenyl borate is 2.5:1.4-1.

5.

9. The method for preparing a flame-retardant mesoporous thermal insulation coating according to claim 1, characterized in that: The dispersant is a modified silane coupling agent, and the preparation method is as follows: (1) adding 3-vinylphenylboronic acid and glycerol to tetrahydrofuran, adding magnesium sulfate desiccant, stirring at room temperature for 24 hours, filtering to remove the magnesium sulfate desiccant, distilling under reduced pressure to remove the solvent, washing, and drying to obtain vinylbenzene borate; (1) adding vinylbenzene borate, γ-methacryloyloxypropyltrimethoxysilane, and a photoinitiator to tetrahydrofuran, reacting under ultraviolet light for 2 to 4 hours to obtain a modified silane coupling agent; In the raw materials of the alkenylphenyl borate, the mass ratio of 3-vinylphenylboric acid to glycerol is 1.5:0.95~1; in the raw materials of the modified silane coupling agent, the mass ratio of alkenylphenyl borate to γ-methacryloxypropyltrimethoxysilane is 1:

1.

10. The flame retardant mesoporous thermal insulation coating prepared according to the method for preparing a flame retardant mesoporous thermal insulation coating according to any one of claims 1 to 9.

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