Flame-retardant mesoporous thermal insulation coating and preparation method thereof

Abstract

This invention discloses a flame-retardant mesoporous thermal insulation coating and its preparation method, relating to the field of coating technology. S1: Prepare a polyurethane-acrylic emulsion; S2: Mix mesoporous material, dispersant, anhydrous ethanol, and deionized water to obtain a mesoporous slurry; S3: Prepare melamine-modified ammonium polyphosphate; S4: Mix hollow microspheres, ethanol, and deionized water, and ultrasonically disperse; add the mesoporous slurry, dipentaerythritol, melamine, melamine-modified ammonium polyphosphate, and dispersant, grind, add the polyurethane-acrylic emulsion and additives, and disperse at medium speed to obtain the flame-retardant mesoporous thermal insulation coating. By designing and optimizing the components, the prepared flame-retardant mesoporous thermal insulation coating, after curing, forms a coating with excellent flame retardancy, thermal insulation, and mechanical properties.

Description

Technical Field

[0001] This invention relates to the field of coating technology, specifically to a flame-retardant mesoporous thermal insulation coating and its preparation method. Background Technology

[0002] High-temperature resistant and flame-retardant mesoporous thermal insulation coatings are a new type of functional coating that combines the unique structural characteristics and high-temperature stability of mesoporous materials. They are widely used in petrochemical, power equipment, building fire protection, and aerospace industries. Mesoporous materials (such as mesoporous silica), with their high specific surface area and controllable pore structure (pore size distribution in the range of 2-50 nm), can effectively reduce heat conduction and convective heat transfer, thereby improving the thermal insulation performance of coatings and becoming an ideal substrate for next-generation lightweight and high-efficiency thermal insulation coatings.

[0003] While there are many types of thermal insulation and flame-retardant coatings 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 insulation. Traditional insulation materials (such as rock wool and calcium silicate boards) possess insulation properties but suffer from high bulk density, poor construction flexibility, susceptibility to moisture absorption and aging, and flammability. Existing flame-retardant thermal insulation coatings often suffer from insufficient structural stability, poor environmental adaptability, and complex construction processes, significantly limiting their application. Furthermore, while widely used phosphorus-based flame retardants offer advantages such as environmental friendliness and good flame-retardant performance, the ammonium polyphosphate component of these agents is highly hygroscopic, disrupting the overall balance of the coating and accelerating its chalking, thus hindering its effective application.

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

[0005] The purpose of this invention is to provide a flame-retardant mesoporous thermal insulation coating and its preparation method, so as to solve the problems mentioned in the background art.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0007] A method for preparing a flame-retardant mesoporous thermal insulation coating includes the following steps:

[0008] S1: (1) Mix methyl methacrylate, butyl acrylate, acrylic acid and ammonium persulfate to obtain solution A; (2) Add solution A dropwise to polyurethane dispersion, control the temperature at 75~80℃, perform free radical polymerization reaction for 4~5 hours, distill under reduced pressure, adjust pH to 7~8, filter, and obtain polyurethane-acrylic emulsion;

[0009] S2: Mix the mesoporous material, dispersant, anhydrous ethanol, and deionized water to obtain a mesoporous slurry;

[0010] 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℃, and after reacting for 2~3 hours, it is cooled, filtered, washed 3~5 times, and vacuum dried to obtain melamine-modified ammonium polyphosphate.

[0011] S4: Mix hollow microspheres, ethanol, and deionized water, and disperse by ultrasonication; add mesoporous slurry, dipentaerythritol, melamine, melamine-modified ammonium polyphosphate, and dispersant, grind, add polyurethane-acrylic emulsion and additives, and disperse at medium speed to obtain flame-retardant mesoporous thermal insulation coating.

[0012] In a more optimized manner, the flame-retardant mesoporous thermal insulation coating comprises the following raw materials in parts by weight: 1-5 parts hollow microspheres, 1-10 parts ethanol, 1-10 parts deionized water, 1-5 parts mesoporous slurry, 5-15 parts dipentaerythritol, 5-15 parts melamine, 10-30 parts melamine-modified ammonium polyphosphate, 1-5 parts dispersant, 20-30 parts polyurethane-acrylic emulsion, and 3-7 parts additives; the additives include one or more of film-forming aids, defoamers, anti-settling agents, leveling agents, wetting agents, and pH adjusters.

[0013] More preferably, solution A comprises the following raw materials in parts by weight: 10-15 parts methyl methacrylate, 10-15 parts butyl acrylate, 2-3 parts acrylic acid, and 0.5-1 parts ammonium persulfate; the polyurethane-acrylic emulsion comprises the following raw materials in parts by weight: 5-10 parts solution A and 12-18 parts polyurethane dispersion; the mesoporous slurry comprises the following raw materials in parts by weight: 5-10 parts mesoporous material, 1-3 parts dispersant, 10-15 parts anhydrous ethanol, and 15-25 parts deionized water;

[0014] The suspension B comprises the following raw materials in parts by weight: 10-15 parts ammonium polyphosphate and 30-50 parts deionized water; the melamine-modified ammonium polyphosphate comprises the following raw materials in parts by weight: 6-15 parts melamine-formaldehyde resin prepolymer and 40-60 parts suspension B.

[0015] 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, heated to 58~62℃ and kept in a water bath for 3~5 min, ammonia water is added, stirred for 1~2 h, centrifuged, washed, dried, heated to 190~210℃ and kept for 1~2 h, and then heated to 640~670℃ and calcined for 15~17 h to obtain hollow mesoporous silica nanospheres; wherein, the mass ratio of nitric acid, phenyltrimethoxysilane, and ammonia water is 1:10:5.

[0016] In a more optimized manner, the preparation method of the melamine-modified ammonium polyphosphate is as follows: deionized water is added to a reaction vessel, the temperature is raised to 60~70℃, melamine and formaldehyde solution are added, stirred and dissolved, the pH is adjusted to 8~9 with ammonia water, and the reaction is kept at the temperature for 1~2 hours to obtain melamine-formaldehyde resin prepolymer.

[0017] A more optimized method for preparing the polyurethane dispersion is as follows: Under nitrogen protection, polyether polyol, isophorone diisocyanate, and dibutyltin dilaurate are added to a reactor, heated to 70-80°C, and reacted for 2-3 hours. Dimethylolpropionic acid and acetone are added, and the reaction continues until the isocyanate group content reaches the standard. The temperature is then lowered to 35-40°C, and triethylamine is added for neutralization. The mixture is stirred for 30-50 minutes, and deionized water is slowly added. The mixture is then emulsified at high speed (1000-2000 rpm) to obtain the polyurethane dispersion. 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. The solid content of the polyurethane dispersion is 55-60%.

[0018] More preferably, the polyether polyol comprises polytetrahydrofuran polyol and phenyl-containing polyol in a mass ratio of 6~7:3~4.

[0019] More optimized, the preparation method of the phenyl-containing polyol is as follows: (1) 1,4-phenyldiboronic acid and 1-thioglycerol ester are added to tetrahydrofuran, magnesium sulfate desiccant is added, the mixture is stirred at room temperature for 24 hours, the magnesium sulfate desiccant is removed by filtration, the solvent is removed by vacuum distillation, and the mixture is washed and dried to obtain dimercaptophenylboronic acid ester; (2) Allyl methanol, dimercaptophenylboronic acid ester and photoinitiator are added to tetrahydrofuran in sequence, and the mixture is reacted under ultraviolet light for 2-4 hours to obtain the phenyl-containing polyol;

[0020] In the raw material of the dimercaptophenylboronic acid ester, the mass ratio of 1,4-phenyldiboronic acid to 1-thioglycerol ester is 1.5:2~2.2;

[0021] In the phenyl polyol-containing raw material, the mass ratio of allyl methanol to dimercaptophenylboronic acid ester is 2.5:1.4~1.5.

[0022] More optimally, the dispersant is a modified silane coupling agent, and the preparation method is as follows: (1) 3-vinylphenylboronic acid and glycerol are added to tetrahydrofuran, magnesium sulfate desiccant is added, the mixture is stirred at room temperature for 24 hours, the magnesium sulfate desiccant is removed by filtration, the solvent is removed by vacuum distillation, and the mixture is washed and dried to obtain alkenylphenylboronic acid ester; (2) alkenylphenylboronic acid ester, γ-methacryloyloxypropyltrimethoxysilane and photoinitiator are added to tetrahydrofuran, and the mixture is reacted under ultraviolet light for 2-4 hours to obtain the modified silane coupling agent;

[0023] In the raw materials of the alkenyl phenylboronic acid ester, the mass ratio of 3-vinylphenylboronic acid to glycerol is 1.5:0.95~1; in the raw materials of the modified silane coupling agent, the mass ratio of alkenyl phenylboronic acid ester to γ-methacryloyloxypropyltrimethoxysilane is 1:1.

[0024] A more optimized method for preparing a flame-retardant mesoporous thermal insulation coating yields a flame-retardant mesoporous thermal insulation coating.

[0025] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0026] (1) This invention provides a heat-resistant and flame-retardant mesoporous thermal insulation coating and its preparation method. The components are designed and optimized. After curing, the prepared coating forms a coating with low thermal conductivity, high flame retardancy, high stability and high adhesion.

[0027] (2) This invention employs an innovative composite flame-retardant system, using melamine resin-coated modified ammonium polyphosphate as the core flame retardant. Uniform coating is achieved through in-situ polymerization. Furthermore, it combines melamine and pentaerythritol to form an intumescent flame-retardant system, which can form a dense char layer during combustion, effectively improving the flame-retardant performance of the coating. At the same time, the introduction of mesoporous slurry enhances the thermal resistance effect of the coating. Its unique multi-level pore structure and high specific surface area effectively reduce the thermal conductivity. The preparation of specific segment polyurethane-acrylic emulsion and the limitation of dispersant further improve the thermal insulation performance.

[0028] Hollow mesoporous silica nanospheres prepared by a special process were used as the thermal insulation material. By optimizing the dispersion process, the mesoporous material was evenly distributed in the coating, constructing a multi-layer thermal insulation system and reducing the thermal conductivity of the coating.

[0029] The polyurethane-acrylic composite emulsion used provides excellent film-forming properties and mechanical properties for the coating, enabling it to possess both high elasticity and strong adhesion. The solution further incorporates benzene-containing polyols and dispersants (modified silane coupling agents) with benzene-boron groups to further improve thermal insulation, mechanical properties, and flame retardancy. Firstly, the benzene-boron group's molecular structure contains benzene rings and BO bonds. The rigid structure of the benzene ring reduces molecular chain vibrations, and the polarity of the BO bonds may scatter phonons (the main heat carriers), thus reducing heat conduction. The resulting dynamic covalent network further hinders heat transfer. Secondly, the pyrolysis of benzene-boron esters generates boron-oxygen free radicals, which can quench highly reactive free radicals such as H• and OH• in the flame, interrupting the combustion chain reaction and promoting dehydration and char formation, resulting in a dense boron-carbon composite layer that isolates heat and oxygen, thereby improving flame retardancy. Thirdly, the benzene-boron group can increase molecular cohesion, thereby improving mechanical properties such as adhesion strength. Detailed Implementation

[0030] The technical solutions in the embodiments of the present invention will be clearly and completely described below. 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] It should be noted that in the following embodiments, the parts are by weight, and all raw materials involved, unless otherwise specified, are commercially available, and there are no special restrictions on the manufacturers of purchase. Exemplary examples include: hollow microspheres of model HS-G; the additives are BYK-329 defoamer, 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.

[0032] Example 1: A method for preparing a flame-retardant mesoporous thermal insulation coating, comprising the following steps:

[0033] S1: Under nitrogen protection, polyether polyol, isophorone diisocyanate and dibutyltin dilaurate were added to the reactor, heated to 70°C and reacted for 2 hours. Dimethylolpropionic acid and a small amount of acetone were added, and the reaction 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 high speed at 1000 rpm to obtain a polyurethane dispersion with a solid content of 58 wt%.

[0034] 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; wherein the polyether polyol is polytetrahydrofuran polyol PTMG-650;

[0035] Methyl methacrylate, butyl acrylate, acrylic acid, and ammonium persulfate are mixed to obtain solution A; the raw material composition of solution A is: 12 parts methyl methacrylate, 10 parts butyl acrylate, 2 parts acrylic acid, and 0.5 parts ammonium persulfate.

[0036] Solution A was added dropwise to the polyurethane dispersion, and the temperature was controlled at 75°C. The free radical polymerization reaction was carried out for 4 hours. Acetone was removed by vacuum distillation, 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.

[0037] S2: Nitric acid and phenyltrimethoxysilane are mixed, heated to 58°C and kept in a water bath for 3 minutes, ammonia is added, and the mixture is stirred for 1 hour. After centrifugation, washing, and drying, the mixture is heated to 200°C and kept for 2 hours, and then calcined at 660°C for 16 hours to obtain hollow mesoporous silica nanospheres, which are used as mesoporous materials. The raw material composition of the mesoporous material is: the mass ratio of nitric acid, phenyltrimethoxysilane, and ammonia is 1:10:5.

[0038] 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 mesoporous material, 2 parts dispersant, 11 parts anhydrous ethanol, and 15 parts deionized water.

[0039] S3: Ammonium polyphosphate and deionized water are mixed and ultrasonically dispersed for 30 minutes to obtain suspension B; the raw material composition of suspension B is: 10 parts of ammonium polyphosphate and 30 parts of deionized water.

[0040] Melamine-formaldehyde resin prepolymer was slowly added dropwise to suspension B, and the temperature was controlled at 70°C. After reacting for 2 hours, the mixture was 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.

[0041] S4: Mix hollow microspheres, ethanol, and deionized water, and disperse them ultrasonically; add mesoporous slurry, dipentaerythritol, melamine, melamine-modified ammonium polyphosphate, and dispersant, grind, add polyurethane-acrylic emulsion and additives, disperse at medium speed, and obtain flame-retardant mesoporous thermal insulation coating.

[0042] The raw material composition of the thermal insulation coating is as follows: 2 parts hollow microspheres, 3 parts ethanol, 7 parts deionized water, 2 parts mesoporous slurry, 5 parts dipentaerythritol, 8 parts melamine, 15 parts melamine-modified coated ammonium polyphosphate, 1 part dispersant, 20 parts polyurethane-acrylic emulsion, and 3 parts additives; the dispersant is γ-methacryloyloxypropyltrimethoxysilane.

[0043] Example 2: A method for preparing a flame-retardant mesoporous thermal insulation coating, comprising the following steps:

[0044] S1: Under nitrogen protection, polyether polyol, isophorone diisocyanate and dibutyltin dilaurate were added to the reactor, heated to 75°C and reacted for 2 hours. Dimethylolpropionic acid and a small amount of acetone were added, and the reaction 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 the mixture was emulsified at high speed at 1500 rpm to obtain a polyurethane dispersion with a solid content of 58 wt%.

[0045] 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; wherein the polyether polyol is polytetrahydrofuran polyol PTMG-650;

[0046] Methyl methacrylate, butyl acrylate, acrylic acid, and ammonium persulfate are mixed to obtain solution A; the raw material composition of solution A is: 10 parts methyl methacrylate, 15 parts butyl acrylate, 2.5 parts acrylic acid, and 1 part ammonium persulfate.

[0047] Solution A was added dropwise to the polyurethane dispersion, and the temperature was controlled at 75°C. The free radical polymerization reaction was carried out for 4 hours. Acetone was removed by vacuum distillation, 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.

[0048] S2: Nitric acid and phenyltrimethoxysilane are mixed, heated to 58°C and kept in a water bath for 3 minutes, ammonia is added, and the mixture is stirred for 1 hour. After centrifugation, washing, and drying, the mixture is heated to 200°C and kept for 2 hours, and then calcined at 660°C for 16 hours to obtain hollow mesoporous silica nanospheres, which are used as mesoporous materials. The raw material composition of the mesoporous material is: the mass ratio of nitric acid, phenyltrimethoxysilane, and ammonia is 1:10:5.

[0049] 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 mesoporous material, 1 part dispersant, 13 parts anhydrous ethanol, and 17 parts deionized water.

[0050] S3: Ammonium polyphosphate and deionized water are mixed and ultrasonically dispersed for 30 minutes to obtain suspension B; the raw material composition of suspension B is: 15 parts of ammonium polyphosphate and 45 parts of deionized water.

[0051] Melamine-formaldehyde resin prepolymer was slowly added dropwise to suspension B, and the temperature was controlled at 70°C. After reacting for 2 hours, the mixture was 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: 10 parts of melamine-formaldehyde resin prepolymer and 50 parts of solution B.

[0052] S4: Mix hollow microspheres, ethanol, and deionized water, and disperse them ultrasonically; add mesoporous slurry, dipentaerythritol, melamine, melamine-modified ammonium polyphosphate, and dispersant, grind, add polyurethane-acrylic emulsion and additives, disperse at medium speed, and obtain flame-retardant mesoporous thermal insulation coating.

[0053] The raw material composition of the thermal insulation coating is as follows: 1 part hollow microspheres, 2 parts ethanol, 5 parts deionized water, 5 parts mesoporous slurry, 7 parts dipentaerythritol, 5 parts melamine, 20 parts melamine-modified coated ammonium polyphosphate, 3 parts dispersant, 25 parts polyurethane-acrylic emulsion, and 4 parts additives; the dispersant is γ-methacryloyloxypropyltrimethoxysilane.

[0054] Example 3: A method for preparing a flame-retardant mesoporous thermal insulation coating, comprising the following steps:

[0055] S1: Under nitrogen protection, polyether polyol, isophorone diisocyanate and dibutyltin dilaurate were added to the reactor, heated to 80°C and reacted 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 the mixture was emulsified at high speed at 2000 rpm to obtain a polyurethane dispersion with a solid content of 58 wt%.

[0056] 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; wherein the polyether polyol is polytetrahydrofuran polyol PTMG-650;

[0057] Methyl methacrylate, butyl acrylate, acrylic acid, and ammonium persulfate are mixed to obtain solution A; the raw material composition of solution A is: 15 parts methyl methacrylate, 13 parts butyl acrylate, 3 parts acrylic acid, and 0.75 parts ammonium persulfate.

[0058] Solution A was added dropwise to the polyurethane dispersion, and the temperature was controlled at 75°C. The free radical polymerization reaction was carried out for 4 hours. Acetone was removed by vacuum distillation, 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.

[0059] S2: Nitric acid and phenyltrimethoxysilane are mixed, heated to 58°C and kept in a water bath for 3 minutes, ammonia is added, and the mixture is stirred for 1 hour. After centrifugation, washing, and drying, the mixture is heated to 200°C and kept for 2 hours, and then calcined at 660°C for 16 hours to obtain hollow mesoporous silica nanospheres, which are used as mesoporous materials. The raw material composition of the mesoporous material is: the mass ratio of nitric acid, phenyltrimethoxysilane, and ammonia is 1:10:5.

[0060] 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 mesoporous material, 3 parts dispersant, 15 parts anhydrous ethanol, and 20 parts deionized water.

[0061] S3: Ammonium polyphosphate and deionized water are mixed and ultrasonically dispersed for 30 minutes to obtain suspension B; by mass parts, the raw material composition of suspension B is: 12 parts of ammonium polyphosphate and 50 parts of deionized water.

[0062] Melamine-formaldehyde resin prepolymer was slowly added dropwise to suspension B, and the temperature was controlled at 70°C. After reacting for 2 hours, the mixture was 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: 15 parts of melamine-formaldehyde resin prepolymer and 60 parts of solution B.

[0063] S4: Mix hollow microspheres, ethanol, and deionized water, and disperse them ultrasonically; add mesoporous slurry, dipentaerythritol, melamine, melamine-modified ammonium polyphosphate, and dispersant, grind, add polyurethane-acrylic emulsion and additives, disperse at medium speed, and obtain flame-retardant mesoporous thermal insulation coating.

[0064] The raw material composition of the thermal insulation coating is as follows: 3 parts hollow microspheres, 7 parts ethanol, 6 parts deionized water, 3 parts mesoporous slurry, 10 parts dipentaerythritol, 10 parts melamine, 25 parts melamine-modified coated ammonium polyphosphate, 5 parts dispersant, 30 parts polyurethane-acrylic emulsion, and 6 parts additives; the dispersant is γ-methacryloyloxypropyltrimethoxysilane.

[0065] Comparative Example 1: Example 3 was used as the control group, except that melamine-modified coated ammonium polyphosphate was replaced with ammonium polyphosphate, while the rest was normal.

[0066] Comparative Example 2: Example 3 served as the control group, except that the mesoporous slurry was removed, while the rest of the components remained normal.

[0067] Example 4: Using Example 3 as the control group, the difference lies in adjusting the preparation of the polyurethane dispersion; other parts are normal; the adjustments are as follows:

[0068] In this embodiment, the polyether polyol in the raw materials for preparing the polyurethane dispersion is composed of polytetrahydrofuran polyol PTMG-650 and 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-thioglycerol in a mass ratio of 1.5:2.1 are added to tetrahydrofuran, magnesium sulfate desiccant is added, the mixture is stirred at room temperature for 24 hours, the magnesium sulfate desiccant is removed by filtration, the solvent is removed by vacuum distillation, and the mixture is washed and dried to obtain dimercaptophenylboronic acid ester; allyl methanol, dimercaptophenylboronic acid ester, and photoinitiator 784 in a mass ratio of 2.5:1.5:0.1 are added to tetrahydrofuran in sequence, and the mixture is reacted under ultraviolet light for 2 hours to obtain the phenyl-containing polyol.

[0069] Example 5: Using Example 3 as the control group, the difference lies in adjusting the preparation of the polyurethane dispersion and the dispersant; other parts are normal; the adjustments are as follows:

[0070] In this embodiment, the polyether polyol in the raw materials for preparing the polyurethane dispersion is composed of polytetrahydrofuran polyol PTMG-650 and 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-phenylenediboronic acid and 1-thioglycerol in a mass ratio of 1.5:2.1 are added to tetrahydrofuran, magnesium sulfate desiccant is added, the mixture is stirred at room temperature for 24 hours, the magnesium sulfate desiccant is removed by filtration, the solvent is removed by vacuum distillation, and the mixture is washed and dried to obtain dimercaptophenylboronic acid ester; allyl methanol, dimercaptophenylboronic acid ester, and photoinitiator 784 in a mass ratio of 2.5:1.5:0.1 are added to tetrahydrofuran in sequence, and the mixture is reacted under ultraviolet light for 2 hours to obtain the phenyl-containing polyol.

[0071] The dispersant is a modified silane coupling agent, and the preparation method is as follows: (1) 3-vinylphenylboronic acid and glycerol with a mass ratio of 1.5:0.95~1 are added to tetrahydrofuran, magnesium sulfate desiccant is added, and the mixture is stirred at room temperature for 24 hours. The magnesium sulfate desiccant is removed by filtration, the solvent is removed by vacuum distillation, and the mixture is washed and dried to obtain alkenylphenylboronic acid ester; (2) alkenylphenylboronic acid ester, γ-methacryloyloxypropyltrimethoxysilane and photoinitiator with a mass ratio of 1:1:0.05 are added to tetrahydrofuran, and the mixture is reacted under ultraviolet light for 2~4 hours to obtain the modified silane coupling agent.

[0072] Comparative Example 3: Example 5 served as the control group, the difference being that the polyether polyol was composed of polytetrahydrofuran polyol PTMG-650 and phenyl-containing polyol in a mass ratio of 3.5:6.5; the other parts were normal.

[0073] Performance Test 1: The flame-retardant mesoporous thermal insulation coatings obtained in Examples 1-5 were coated and cured on a 100mm×150mm×3mm steel plate to form a 5mm thick coating, and relevant performance tests were conducted; (1) Flame retardancy test: The flame retardancy rating was tested according to GB8624-2012; (2) Salt spray test: A 1000h salt spray test was conducted according to GB / T1771-2007, and the coating was observed to show any abnormalities after the test; (3) Aging test: A 500h xenon lamp aging test was conducted according to GB / T1865-2009, and the coating was observed to show any abnormalities after the test. The results are shown in Table 1:

[0074] Table 1:

[0075]

[0076] Performance Test 2: The flame-retardant mesoporous thermal insulation coatings obtained in Examples 1-5 and Comparative Examples 1-3 were used as substrates on a 100mm×150mm×3mm steel plate. (1) After coating and curing, a 1mm thick coating was formed. A pull-out test was conducted according to GB / T 5210 to obtain the adhesion. (2) After coating and curing, a 5mm thick coating was formed. The thermal insulation properties of the coating were tested at 80℃, 120℃, and 160℃. The results are shown in Table 2.

[0077] Table 2:

[0078]

[0079] Conclusion: The data in Table 1 show that this application has prepared a flame-retardant mesoporous thermal insulation coating with excellent flame retardancy and stability. The melamine-coated ammonium polyphosphate improves the flame-retardant efficiency of the coating while avoiding the negative impact of the strong hygroscopicity of unmodified ammonium polyphosphate on the coating stability, ensuring that the coating maintains stable flame-retardant performance under various environments. The coating showed no abnormalities in salt spray and aging resistance tests, indicating excellent long-term durability. It can be widely used in fireproofing and thermal insulation applications in buildings, industrial equipment, and other fields, and has significant engineering application value.

[0080] The data in Table 2 show that the application effectively ensures adhesion through component optimization and preparation method limitation. At the same time, the introduction of mesoporous slurry enhances the thermal resistance effect of the coating. Its unique multi-level pore structure and high specific surface area effectively reduce the thermal conductivity. Furthermore, the preparation of specific segment polyurethane-acrylic emulsion and the limitation of dispersant enable the coating to exhibit excellent thermal insulation performance in thermal environment tests at 80℃, 120℃, and 160℃.

[0081] In Comparative Example 1, when ammonium polyphosphate was used in the preparation of thermal insulation coating, the addition of unmodified ammonium polyphosphate, which has strong hygroscopicity, would disrupt the balance and stability of the coating system, causing stress concentration in the coating film, and ultimately resulting in drying shrinkage and cracking of the coating, leading to a decline in related performance.

[0082] In Comparative Example 2, due to its unique pore size distribution, high specific surface area, and multi-level pore structure, the thermal resistance effect of the coating can be significantly enhanced, thereby improving the thermal insulation performance. However, after removing the mesoporous slurry, performance tests revealed that the thermal conductivity of the coating increased and the heat flux density rose, resulting in a significant decrease in its thermal insulation performance compared to Example 3.

[0083] In Example 4, a further scheme based on Example 3 is proposed, in which phenylboron-containing groups are introduced into the polyurethane dispersion, so that a heat-insulating network is generated in the coating crosslinking network, which synergistically improves the heat insulation performance with the mesoporous coating.

[0084] In Example 5, a further embodiment of Example 3 is proposed. In addition to adjusting the polyether polyol in the polyurethane dispersion, a modified coupling agent containing similar functional groups is further introduced, thereby improving the compatibility of the mesoporous material and enhancing its thermal insulation properties.

[0085] In Comparative Example 3, it can be found that when too much phenyl polyol is introduced into the polyether polyol of the polyurethane dispersion, the heat insulation performance is not improved. Instead, it disrupts the balance and stability between the coating systems, resulting in a decrease in related performance.

[0086] 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 foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a flame-retardant mesoporous thermal insulation coating, characterized in that: Includes the following steps: S1: (1) Mix methyl methacrylate, butyl acrylate, acrylic acid and ammonium persulfate to obtain solution A; (2) Add solution A dropwise to polyurethane dispersion, control the temperature at 75~80℃, perform free radical polymerization reaction for 4~5 hours, distill under reduced pressure, adjust pH to 7~8, filter, and obtain polyurethane-acrylic emulsion; S2: Mix 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℃, and after reacting for 2~3 hours, it 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 dispersant are added, and the mixture is ground; polyurethane-acrylic emulsion and additives are added, and the mixture is dispersed at medium speed to obtain a flame-retardant mesoporous thermal insulation coating; The polyurethane dispersion is prepared as follows: Under nitrogen protection, polyether polyol, isophorone diisocyanate, and dibutyltin dilaurate are added to a reactor, heated to 70-80°C, and reacted for 2-3 hours. Dimethylolpropionic acid and acetone are added, and the reaction continues until the isocyanate group content reaches the standard. The temperature is then lowered to 35-40°C, and triethylamine is added for neutralization. The mixture is stirred for 30-50 minutes, and deionized water is slowly added. The mixture is then emulsified under high-speed shear at 1000-2000 rpm to obtain the polyurethane dispersion. 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. The solid content of the polyurethane dispersion is 55-60%. The polyether polyol includes polytetrahydrofuran polyol and phenyl-containing polyol in a mass ratio of 6~7:3~4; The preparation method of the phenyl-containing polyol is as follows: (1) 1,4-phenyldiboronic acid and 1-thioglycerol are added to tetrahydrofuran, magnesium sulfate desiccant is added, the mixture is stirred at room temperature for 24 hours, magnesium sulfate desiccant is removed by filtration, solvent is removed by vacuum distillation, and the mixture is washed and dried to obtain dimercaptophenylboronic acid ester; (2) Allyl methanol, dimercaptophenylboronic acid ester and photoinitiator are added to tetrahydrofuran in sequence, and the mixture is reacted under ultraviolet light for 2-4 hours to obtain the phenyl-containing polyol; The dispersant is a modified silane coupling agent, and the preparation method is as follows: (1) 3-vinylphenylboronic acid and glycerol are added to tetrahydrofuran, magnesium sulfate desiccant is added, and the mixture is stirred at room temperature for 24 hours. The magnesium sulfate desiccant is removed by filtration, the solvent is removed by vacuum distillation, and the mixture is washed and dried to obtain alkenylphenylboronic acid ester; (2) alkenylphenylboronic acid ester, γ-methacryloyloxypropyltrimethoxysilane and photoinitiator are added to tetrahydrofuran and reacted under ultraviolet light for 2-4 hours to obtain the modified silane coupling agent.

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 comprises the following raw materials in parts by weight: 1-5 parts hollow microspheres, 1-10 parts ethanol, 1-10 parts deionized water, 1-5 parts mesoporous slurry, 5-15 parts dipentaerythritol, 5-15 parts melamine, 10-30 parts melamine-modified ammonium polyphosphate, 1-5 parts dispersant, 20-30 parts polyurethane-acrylic emulsion, and 3-7 parts additives; the additives include one or more of film-forming aids, defoamers, anti-settling agents, leveling agents, wetting agents, and pH adjusters.

3. The method for preparing a flame-retardant mesoporous thermal insulation coating according to claim 1, characterized in that: Solution A comprises the following raw materials in parts by weight: 10-15 parts methyl methacrylate, 10-15 parts butyl acrylate, 2-3 parts acrylic acid, and 0.5-1 parts ammonium persulfate; the polyurethane-acrylic emulsion comprises the following raw materials in parts by weight: 5-10 parts solution A and 12-18 parts polyurethane dispersion; the mesoporous slurry comprises the following raw materials in parts by weight: 5-10 parts mesoporous material, 1-3 parts dispersant, 10-15 parts anhydrous ethanol, and 15-25 parts deionized water; The suspension B comprises the following raw materials in parts by weight: 10-15 parts ammonium polyphosphate and 30-50 parts deionized water; the melamine-modified ammonium polyphosphate comprises the following raw materials in parts by weight: 6-15 parts melamine-formaldehyde resin prepolymer and 40-60 parts 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℃ and kept in a water bath for 3-5 minutes, ammonia is added, stirred for 1-2 hours, centrifuged, washed, and dried, heated to 190-210℃ and kept for 1-2 hours, and then calcined at 640-670℃ for 15-17 hours to obtain hollow mesoporous silica nanospheres; wherein the mass ratio of nitric acid, phenyltrimethoxysilane, and ammonia is 1:10:

5.

5. The method for preparing a flame-retardant mesoporous thermal insulation coating according to claim 1, characterized in that: The method for preparing the melamine-formaldehyde resin prepolymer is as follows: deionized water is added to a reaction vessel, the temperature is raised to 60-70°C, melamine and formaldehyde solutions are added, stirred and dissolved, the pH is adjusted to 8-9 with ammonia water, and the reaction is kept at the temperature for 1-2 hours to obtain the melamine-formaldehyde resin prepolymer.

6. The method for preparing a flame-retardant mesoporous thermal insulation coating according to claim 1, characterized in that: In the raw material of the dimercaptophenylboronic acid ester, the mass ratio of 1,4-phenyldiboronic acid to 1-thioglycerol is 1.5:2~2.2; In the phenyl polyol-containing raw material, the mass ratio of allyl methanol to dimercaptophenylboronic acid ester is 2.5:1.4~1.

5.

7. The method for preparing a flame-retardant mesoporous thermal insulation coating according to claim 1, characterized in that: In the raw materials of the alkenyl phenylboronic acid ester, the mass ratio of 3-vinylphenylboronic acid to glycerol is 1.5:0.95~1; in the raw materials of the modified silane coupling agent, the mass ratio of alkenyl phenylboronic acid ester to γ-methacryloyloxypropyltrimethoxysilane is 1:

1.

8. The flame-retardant mesoporous thermal insulation coating prepared by the preparation method of the flame-retardant mesoporous thermal insulation coating according to any one of claims 1 to 7.

Images