Self-cleaning waterproof coating and preparation method thereof

Abstract

The application discloses a self-cleaning waterproof coating and a preparation method thereof, and relates to the technical field of waterproof coatings. The waterproof coating is prepared from organic silicon modified acrylic resin emulsion, photocatalyst nanocomposite material, hydrophobic modified silica aerogel powder, nanofiber reinforcing material, dispersant, film forming aid, thickening agent, defoaming agent and deionized water. The compatibility design of the core-shell structure photocatalyst and the super-hydrophobic silica aerogel realizes the multiple self-cleaning of adsorption-degradation-flushing, significantly improves the durability and reliability of the self-cleaning, and the surface modified nanofiber is used as the reinforcing material, which forms a three-dimensional network structure in the coating film, cooperates with the flexibility of the organic silicon modified acrylic resin, improves the tensile strength and deformation resistance of the coating, avoids the brittleness of the rigid particles, and significantly improves the durability of the coating.

Description

Technical Field

[0001] This invention relates to the field of waterproof coating technology, and in particular to a self-cleaning waterproof coating and its preparation method. Background Technology

[0002] Paint is a viscous liquid that is applied to the surface of an object to be protected or decorated and forms a continuous film that adheres firmly to the object. It is usually based on resin, oil, or emulsion, with or without pigments and fillers, and with appropriate additives, and is prepared with organic solvents or water.

[0003] Waterproof coatings are solvent-based, water-emulsion, or powder coatings made by adding various additives, modifiers, and fillers, with synthetic polymers, polymers and asphalt, or polymers and cement as the main film-forming substances.

[0004] Waterproof coatings are applied to the surfaces of buildings such as roofs, basements, toilets, bathrooms, and exterior walls that require waterproofing. Under normal temperature conditions, they can form a continuous, integral waterproof layer of a certain thickness.

[0005] Existing waterproof coatings often rely on a single technology (such as a simple superhydrophobic surface or a single photocatalytic coating) for self-cleaning function. This is prone to performance degradation due to surface contamination or deactivation of photocatalytic components. Furthermore, traditional waterproof coatings often increase coating brittleness due to the addition of rigid nanoparticles (such as silica and titanium dioxide), making them susceptible to failure due to substrate cracking. In addition, traditional waterproof coatings also suffer from problems such as easy agglomeration of nanofillers and poor compatibility between organic and inorganic functional components. Therefore, this invention proposes a self-cleaning waterproof coating and its preparation method to solve the problems existing in the prior art. Summary of the Invention

[0006] To address the aforementioned problems, the present invention aims to propose a self-cleaning waterproof coating and its preparation method, thereby solving the problems of existing waterproof coating products being prone to performance degradation due to surface contamination or deactivation of photocatalytic components, and easily failing due to substrate cracking, as well as the tendency of nanofillers in waterproof coatings to agglomerate and the poor compatibility between organic and inorganic functional components.

[0007] To achieve the objectives of this invention, the following technical solution is provided: A self-cleaning waterproof coating, comprising the following raw materials in parts by weight: 30-50 parts of organosilicon-modified acrylic resin emulsion, 3-8 parts of photocatalyst nanocomposite material, 5-12 parts of hydrophobic-modified silica aerogel powder, 2-5 parts of nanofiber reinforcing material, 0.5-1.5 parts of dispersant, 1-3 parts of film-forming aid, 0.2-1.0 parts of thickener, 0.1-0.5 parts of defoamer, and 20-35 parts of deionized water;

[0008] The photocatalyst nanocomposite material has a core-shell structure, with the core being nano-titanium dioxide and the outer shell being a porous silica layer;

[0009] The nano-titanium dioxide is modified by co-doping with rare earth elements lanthanum and cerium;

[0010] The nanofiber reinforcing material is either cellulose nanofiber or polyvinyl alcohol nanofiber that has been surface modified with silane coupling agent KH-550.

[0011] A further improvement is that: the film-forming aid is a mixture of dodecyl alcohol ester and propylene glycol phenyl ether in a mass ratio of 2:1; the dispersant is sodium polyacrylate dispersant; the thickener is a hydrophobically modified alkali-swelling thickener; and the defoamer is an organosilicon defoamer.

[0012] A further improvement is made in the following specific preparation method of the photocatalyst nanocomposite material: titanium source, lanthanum source, and cerium source are mixed in a molar ratio of 100-xy:x:y, where x = 0.5-2 and y = 0.5-2. Deionized water and surfactant are then added to the mixture, with the mass ratio of the mixture, deionized water, and surfactant being 100:300-600:0.5-2. A precursor sol is generated through a hydrolysis-condensation reaction, and a porous silica layer is coated on the surface using the sol-gel method. After calcination, a core-shell structure is formed.

[0013] A further improvement is made in the following specific preparation method of the hydrophobic modified silica aerogel powder: silica aerogel particles are mixed with fluorinated silane at a molar mass ratio of 100:1 to 5, ultrasonically dispersed in an ethanol-water mixed solvent, and then dried to obtain the powder.

[0014] A further improvement is made in that the surface modification method of the nanofiber reinforced material is as follows: cellulose nanofibers or polyvinyl alcohol nanofibers are dispersed in an ethanol-water mixed solution, silane coupling agent KH-550 is added, the mixture is ultrasonically dispersed, heated to 60-80℃ and stirred, and then centrifuged and dried to obtain the final product.

[0015] A method for preparing a self-cleaning waterproof coating includes the following steps:

[0016] Step 1: Prepare all raw materials in advance. Under light-protected conditions, add 40% to 50% deionized water, dispersant, and 50% defoamer to a high-speed disperser and stir. Add hydrophobic modified silica aerogel powder and photocatalyst nanocomposite material, and continue stirring and dispersing to obtain slurry A.

[0017] Step 2: Add the nanofiber reinforcing material to the remaining deionized water, first sonicate it, then mechanically stir it to obtain nanofiber suspension B;

[0018] Step 3: Add the silicone-modified acrylic resin emulsion to a low-speed stirring tank, and slowly add slurry A, film-forming aid, thickener and remaining defoamer in sequence, and continue stirring until the mixture is uniform, which is called mixture C;

[0019] Step 4: Add nanofiber suspension B to mixture C and stir. Adjust the pH to 8.0-9.0 with ammonia water, then transfer to a sealed container and mature under light-protected conditions to obtain the final self-cleaning waterproof coating.

[0020] A further improvement is that, in step one, the light-shielding condition is achieved by a glass reactor wrapped with aluminum foil, and the stirring shaft of the high-speed disperser is made of UV-resistant material.

[0021] A further improvement is made in step four, during the maturation process, the mixture is stirred at a low speed of 100 rpm for 5 minutes every 4 hours.

[0022] The beneficial effects of this invention are as follows: This invention achieves multiple self-cleaning processes of adsorption-degradation-washing through the compatibility design of a core-shell structured photocatalyst and a superhydrophobic silica aerogel: the porous silica shell enhances the adsorption sites of pollutants, and rare earth co-doping broadens the light response range of titanium dioxide, enabling it to efficiently degrade pollutants under visible light; while the superhydrophobic aerogel surface significantly reduces the probability of liquid pollutant adhesion, unattached pollutants can be washed away by rainwater, and attached pollutants are also decomposed by photocatalysis, significantly improving the durability and reliability of self-cleaning.

[0023] Furthermore, surface-modified nanofibers are used as reinforcing materials, forming a three-dimensional network structure in the coating film. This structure complements the flexibility of the silicone-modified acrylic resin, improving the tensile strength and deformation resistance of the coating while avoiding the brittleness of rigid particles. This structural design allows the coating to maintain its integrity even when the substrate cracks, significantly extending the service life of the waterproof layer. It performs particularly well in complex environments with large temperature variations and long-term stress.

[0024] Furthermore, the synergistic effect of dispersants and thickeners, combined with the polarity matching design of hydrophobic modified aerogel and organosilicon resin, effectively reduces the dispersion and aggregation of nanoparticles. At the same time, the preparation process employs light-shielded dispersion, low-speed mixing, and sealed curing processes to avoid premature consumption of photocatalysts and volatilization of organic components, ensuring the storage stability of the coating. In addition, the weather resistance and UV resistance of organosilicon resin, combined with the three-dimensional network structure of nanofibers, enable the coating to maintain good waterproof performance and appearance integrity even after long-term exposure to humid and polluted environments, significantly improving overall durability. Attached Figure Description

[0025] Figure 1This is a schematic diagram of the preparation method of the self-cleaning waterproof coating of the present invention. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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.

[0027] Coatings are liquid or powdered materials that form a continuous film on the surface of an object, providing protection, decoration, or special functions (such as waterproofing, fireproofing, and conductivity). Their core components are film-forming substances, functional components, and media. Film-forming substances mainly include resins / polymers and cement-based materials, functional components mainly include pigments, fillers, and additives, and media mainly include water-based coatings and solvent-based coatings. Coatings can be classified according to their function into waterproof coatings, fireproof coatings, anti-corrosion coatings, and penetrating crystalline coatings.

[0028] Waterproof coatings are functional coating materials that form a continuous waterproof membrane on the surface of a building to prevent water penetration. They are mainly composed of synthetic polymers, polymers with asphalt, or polymers with cement as the main film-forming substances, and are processed with various additives, modifiers, and fillers. These coatings can be solvent-based, water-emulsion-based, or powder-based. When applied to the base surface of a building, such as roofs, basements, toilets, bathrooms, and exterior walls, which require waterproofing, they can form a continuous, integral waterproof layer of a certain thickness under normal temperature conditions.

[0029] It should be noted that the technical means not described in detail in the embodiments of the present invention can be implemented by conventional means and are not the key points of the invention, so they will not be elaborated upon.

[0030] Example 1

[0031] This embodiment provides a self-cleaning waterproof coating, comprising the following raw materials in parts by weight:

[0032] 30 parts of silicone-modified acrylic resin emulsion, with a solid content of 45% and siloxane segments accounting for 8% of the total weight of the resin;

[0033] Three photocatalyst nanocomposites were prepared, each with a core-shell structure. The core was nano-titanium dioxide (TiO2), and the outer shell was a porous silica (SiO2) layer with a thickness of 5 nm and a coverage of more than 95%. The nano-titanium dioxide was modified by co-doping with rare earth elements lanthanum (La) and cerium (Ce). The molar ratio of La and Ce was 0.5% and the molar ratio of La to Ce was 1:1.

[0034] Five parts of hydrophobically modified silica aerogel powder, with a particle size of 5 μm, a porosity >90%, and a specific surface area of ​​600 m², were obtained. 2 / g, water contact angle >150°;

[0035] Two portions of nanofiber reinforced material were prepared, consisting of cellulose nanofibers or polyvinyl alcohol nanofibers with a diameter of 50 nm and a length of 10 μm, which were surface-modified with silane coupling agent KH-550.

[0036] 0.5 parts of dispersant, which is sodium polyacrylate dispersant, with a pH of 7 for a 2% aqueous solution;

[0037] One part of film-forming aid is a mixture of dodecyl alcohol ester and propylene glycol phenyl ether in a mass ratio of 2:1;

[0038] 0.2 parts of thickener, which is a hydrophobically modified alkali-swellable thickener (HASE), has a viscosity of 5000 mPa·s at 25°C;

[0039] 0.1 parts of defoamer, which is an organosilicon defoamer, whose active ingredient is polyether-modified polydimethylsiloxane, with a solid content of 30%;

[0040] 20 parts deionized water.

[0041] In this embodiment, the preparation method of the photocatalyst nanocomposite material includes the following steps:

[0042] A mixture was prepared by mixing a titanium source (tetrabutyl titanate) with a lanthanum source (lanthanum nitrate) and a cerium source (cerium nitrate) in a molar ratio of (100-xy):x:y (x = 0.5, y = 0.5, x:y = 1:1);

[0043] Deionized water and surfactant (polyethylene glycol) are added to the mixture, with a mass ratio of 100:300:0.5. The precursor sol is generated by hydrolysis and polycondensation reaction.

[0044] A porous silica layer (silicon source: tetraethyl orthosilicate) is then coated onto the surface of the precursor sol using the sol-gel method, and a core-shell structure is formed after calcination (400℃, 2h).

[0045] In this embodiment, the preparation method of hydrophobically modified silica aerogel powder includes the following steps:

[0046] Silica aerogel particles and fluorinated silane (1H,1H,2H,2H-perfluorooctyltrimethoxysilane) were mixed at a molar mass ratio (based on SiO2) of 100:1.

[0047] It was prepared by ultrasonic dispersion (power 200W, time 30min) in an ethanol-water mixed solvent (ethanol volume fraction 60%), followed by drying (60℃, vacuum degree < -0.09MPa);

[0048] Its hydrophobic angle, as measured by a contact angle meter (water droplet volume 5μL, ambient humidity 40%), is >150°.

[0049] In this embodiment, the surface modification method for nanofiber reinforced materials includes the following steps:

[0050] Cellulose nanofibers or polyvinyl alcohol nanofibers were dispersed in an ethanol-water mixed solution (volume ratio 7:3), and silane coupling agent KH-550 (mass fraction 0.5%) was added. After ultrasonic dispersion (200W, 15min), the mixture was heated to 60℃ and stirred (1000rpm, 2h). After centrifugation (5000rpm, 10min) and drying (50℃, 12h), the nanofibers were obtained.

[0051] See Figure 1 This embodiment also provides a method for preparing a self-cleaning waterproof coating, including the following steps:

[0052] Step 1: Pre-dispersion

[0053] Under light-protected conditions (achieved by a glass reactor wrapped with aluminum foil, with a light-blocking rate >99%), deionized water (40% of the total amount), dispersant, and 50% defoamer were added to a high-speed disperser (the surface of the disperser's stirring shaft was coated with polytetrafluoroethylene as a UV-resistant material). The mixture was stirred at 500 rpm for 5 minutes (temperature control: circulating water cooling, material temperature ≤40℃). Then, hydrophobic modified silica aerogel powder and photocatalyst nanocomposite material were slowly added (feeding time 10 minutes). The speed was increased to 1500 rpm and dispersed for 20 minutes to obtain a uniform slurry A.

[0054] Step 2: Nanofiber Dispersion

[0055] The nanofiber reinforcing material was added to the remaining deionized water (60% of the total amount), and then subjected to ultrasonic treatment (300W power, 15min), followed by mechanical stirring at 1000rpm for 30min to obtain nanofiber suspension B (1% solid content).

[0056] Step 3: Emulsion Mixing

[0057] Add the silicone-modified acrylic resin emulsion to a low-speed stirring tank (stirring blade diameter to tank diameter ratio 1:3), and slowly add slurry A, film-forming aid, thickener and remaining defoamer at 200 rpm (addition time 15 min), and continue stirring for 15 min to obtain mixture C.

[0058] Step 4: Final Mixing and Maturation

[0059] Add the nanofiber suspension B to the mixture C prepared in step three at 300 rpm and stir for 20 min (scraping the wall every 5 min during this period). Adjust the pH to 8.0 with ammonia (25%) and then transfer it to a sealed container. Cure at 20°C in the dark for 24 h. During the curing process, stir the mixture at low speed (100 rpm, 5 min) every 4 h to prevent the nanofibers from settling. After curing, the final self-cleaning waterproof coating is obtained.

[0060] Example 2

[0061] This embodiment provides a self-cleaning waterproof coating, comprising the following raw materials in parts by weight:

[0062] 50 parts of silicone-modified acrylic resin emulsion, with a solid content of 50% and siloxane segments accounting for 15% of the total weight of the resin;

[0063] Eight portions of photocatalyst nanocomposite materials were prepared, which adopted a core-shell structure. The core was nano-titanium dioxide (TiO2), and the outer shell was a porous silica (SiO2) layer with a thickness of 20 nm and a coverage rate of more than 95%. Among them, the nano-titanium dioxide was modified by co-doping with rare earth elements lanthanum (La) and cerium (Ce). The molar ratio of La and Ce was 2% and the molar ratio of La to Ce was 1:2.

[0064] Twelve parts of hydrophobically modified silica aerogel powder, with a particle size of 25 μm, a porosity >90%, and a specific surface area of ​​800 m², were obtained. 2 / g, water contact angle >150°;

[0065] Five parts of nanofiber reinforced material were used, which were cellulose nanofibers or polyvinyl alcohol nanofibers with a diameter of 200 nm and a length of 50 μm, modified by silane coupling agent KH-550.

[0066] 1.5 parts of dispersant, which is sodium polyacrylate dispersant, with a pH of 9 in a 2% aqueous solution;

[0067] Three parts of film-forming aid are a mixture of dodecyl alcohol ester and propylene glycol phenyl ether in a mass ratio of 2:1;

[0068] Thickener 1.0 part, is a hydrophobically modified alkali-swellable thickener (HASE), with a viscosity of 10000 mPa·s at 25℃;

[0069] 0.5 parts of defoamer, which is an organosilicon defoamer, whose active ingredient is polyether-modified polydimethylsiloxane, with a solid content of 50%;

[0070] 35 parts of deionized water.

[0071] In this embodiment, the preparation method of the photocatalyst nanocomposite material includes the following steps:

[0072] A mixture was prepared by mixing a titanium source (titanium isopropoxide) with a lanthanum source (lanthanum nitrate) and a cerium source (cerium nitrate) in a molar ratio of (100-xy):x:y (x=1, y=2, x:y=1:2);

[0073] Deionized water and surfactant (polyethylene glycol) are added to the mixture. The mass ratio of the mixture, deionized water and surfactant is 50:300:1. A precursor sol is generated by hydrolysis and polycondensation reaction.

[0074] A porous silica layer (silicon source: tetraethyl orthosilicate) is then coated onto the surface of the precursor sol using the sol-gel method, and a core-shell structure is formed after calcination (600℃, 4h).

[0075] In this embodiment, the preparation method of hydrophobically modified silica aerogel powder includes the following steps:

[0076] Silica aerogel particles were mixed with fluorinated silane (1H,1H,2H,2H-perfluorooctyltrimethoxysilane) at a molar mass ratio (based on SiO2) of 20:1.

[0077] It was prepared by ultrasonic dispersion (300W, 60min) in an ethanol-water mixed solvent (80% ethanol by volume) and drying (80℃, vacuum < -0.09MPa);

[0078] Its hydrophobic angle, as measured by a contact angle meter (water droplet volume 5μL, ambient humidity 60%), is >150°.

[0079] In this embodiment, the surface modification method for nanofiber reinforced materials includes the following steps:

[0080] Cellulose nanofibers or polyvinyl alcohol nanofibers were dispersed in an ethanol-water mixture (volume ratio 7:3), and silane coupling agent KH-550 (mass fraction 2%) was added. The mixture was ultrasonically dispersed (200W, 15min), heated to 80℃ and stirred (1000rpm, 2h). After centrifugation (5000rpm, 10min) and drying (50℃, 12h), the nanofibers were obtained.

[0081] See Figure 1 This embodiment also provides a method for preparing a self-cleaning waterproof coating, including the following steps:

[0082] Step 1: Pre-dispersion

[0083] Under light-protected conditions (achieved by a glass reactor wrapped with aluminum foil, with a light-blocking rate >99%), deionized water (50% of the total amount), dispersant, and 50% of defoamer were added to a high-speed disperser (the surface of the disperser's stirring shaft was coated with polytetrafluoroethylene as a UV-resistant material). The mixture was stirred at 800 rpm for 5 minutes (temperature control: circulating water cooling, material temperature ≤40℃). Then, hydrophobic modified silica aerogel powder and photocatalyst nanocomposite material were slowly added (feeding time 15 minutes). The speed was increased to 2000 rpm and dispersed for 40 minutes to obtain a uniform slurry A.

[0084] Step 2: Nanofiber Dispersion

[0085] The nanofiber reinforcing material was added to the remaining deionized water (50% of the total amount), and then subjected to ultrasonic treatment (300W, 15min) and mechanical stirring at 1200rpm for 30min to obtain nanofiber suspension B (3% solid content).

[0086] Step 3: Emulsion Mixing

[0087] Add the silicone-modified acrylic resin emulsion to a low-speed stirring tank (stirring blade diameter to tank diameter ratio 1:3), and slowly add slurry A, film-forming aid, thickener and remaining defoamer in sequence at 400 rpm (addition time 20 min), and continue stirring for 15 min to obtain mixture C.

[0088] Step 4: Final Mixing and Maturation

[0089] Add the nanofiber suspension B to the mixture C prepared in step three at 500 rpm and stir for 20 min (scraping the wall every 5 min during this period). Adjust the pH to 9.0 with ammonia (28%) and then transfer it to a sealed container. Cure at 30°C in the dark for 24 h. During the curing process, stir the mixture at low speed (100 rpm, 5 min) every 4 h to prevent the nanofibers from settling. After curing, the final self-cleaning waterproof coating is obtained.

[0090] The self-cleaning waterproof coatings prepared in Examples 1 and 2 of this invention both meet the following performance requirements:

[0091] Superhydrophobic properties: Static contact angle with water ≥155°, roll-off angle ≤5° (Test method: GB / T 30447-2013);

[0092] Self-cleaning performance: The degradation efficiency of methylene blue simulated pollutant (concentration 0.1g / L, solution volume 50mL) under visible light (λ≥420nm) irradiation is ≥90% within 24h (test method: absorbance is measured by UV-Vis spectrophotometer and degradation rate is calculated);

[0093] Mechanical properties: In accordance with GB / T 528-2009, elongation at break ≥450%;

[0094] Tensile strength ≥3.5MPa; according to GB / T 16777-2008, tensile strength retention rate (after 1000 cycles) ≥80%;

[0095] Aging resistance: According to GB / T 9755-2014, after 1000 hours of artificial accelerated aging, the coating film shows no chalking, blistering, or cracking, with a gloss loss rate of ≤10% and a stain resistance retention rate (compared to the initial contact angle decrease) of ≥85%.

[0096] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. 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 self-cleaning waterproof coating, characterized in that, The raw materials include the following parts by weight: 30-50 parts of silicone-modified acrylic resin emulsion, 3-8 parts of photocatalyst nanocomposite material, 5-12 parts of hydrophobic modified silica aerogel powder, 2-5 parts of nanofiber reinforcing material, 0.5-1.5 parts of dispersant, 1-3 parts of film-forming aid, 0.2-1.0 parts of thickener, 0.1-0.5 parts of defoamer, and 20-35 parts of deionized water; The photocatalyst nanocomposite material has a core-shell structure, with the core being nano-titanium dioxide and the outer shell being a porous silica layer; The nano-titanium dioxide is modified by co-doping with rare earth elements lanthanum and cerium; The nanofiber reinforcing material is one of cellulose nanofibers or polyvinyl alcohol nanofibers that have been surface modified with silane coupling agent KH-550. The specific preparation method of the photocatalyst nanocomposite material is as follows: titanium source, lanthanum source, and cerium source are mixed in a molar ratio of 100-xy:x:y, where x=0.5-2 and y=0.5-2. Deionized water and surfactant are then added to the mixture, and the mass ratio of the mixture, deionized water, and surfactant is 100:300-600:0.5-2. A precursor sol is generated by hydrolysis and condensation reaction, and a porous silica layer is coated on the surface by the sol-gel method. After calcination, a core-shell structure is formed.

2. The self-cleaning waterproof coating according to claim 1, characterized in that: The film-forming aid is a mixture of dodecyl alcohol ester and propylene glycol phenyl ether in a mass ratio of 2:1; the dispersant is sodium polyacrylate dispersant; the thickener is a hydrophobically modified alkali-swelling thickener; and the defoamer is an organosilicon defoamer.

3. The self-cleaning waterproof coating according to claim 1, characterized in that: The specific preparation method of the hydrophobic modified silica aerogel powder is as follows: silica aerogel particles are mixed with fluorinated silane at a molar mass ratio of 100:1 to 5, ultrasonically dispersed in an ethanol-water mixed solvent, and then dried to obtain the powder.

4. The self-cleaning waterproof coating according to claim 1, characterized in that: The surface modification method of the nanofiber reinforced material is as follows: cellulose nanofibers or polyvinyl alcohol nanofibers are dispersed in an ethanol-water mixed solution, silane coupling agent KH-550 is added, the mixture is ultrasonically dispersed, heated to 60-80℃ and stirred, and then centrifuged and dried to obtain the final product.

5. A method for preparing a self-cleaning waterproof coating according to any one of claims 1-4, characterized in that, Includes the following steps: Step 1: Prepare all raw materials in advance. Under light-protected conditions, add 40% to 50% deionized water, dispersant, and 50% defoamer to a high-speed disperser and stir. Add hydrophobic modified silica aerogel powder and photocatalyst nanocomposite material, and continue stirring and dispersing to obtain slurry A. Step 2: Add the nanofiber reinforcing material to the remaining deionized water, first sonicate it, then mechanically stir it to obtain nanofiber suspension B; Step 3: Add the silicone-modified acrylic resin emulsion to a low-speed stirring tank, and slowly add slurry A, film-forming aid, thickener and remaining defoamer in sequence, and continue stirring until the mixture is uniform, which is called mixture C; Step 4: Add nanofiber suspension B to mixture C and stir. Adjust the pH to 8.0-9.0 with ammonia water, then transfer to a sealed container and mature under light-protected conditions to obtain the final self-cleaning waterproof coating.

6. The method for preparing a self-cleaning waterproof coating according to claim 5, characterized in that: In step one, the light-shielding condition is achieved by wrapping the glass reactor with aluminum foil, and the stirring shaft of the high-speed disperser is made of UV-resistant material.

7. The method for preparing a self-cleaning waterproof coating according to claim 5, characterized in that: In step four, during the maturation process, the mixture is stirred at low speed once every 4 hours, with a stirring speed of 100 rpm and a stirring time of 5 minutes.

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