A self-cleaning reflective heat-insulating and waterproof coating and its preparation method

Abstract

This invention relates to the field of coating technology and discloses a self-cleaning reflective heat-insulating and waterproof coating and its preparation method. The coating comprises deionized water, binder, dispersant, reflective heat-insulating powder, wollastonite, precipitated barium sulfate, modified organosilicon hydrophobic agent, and associative thickener. The reflective heat-insulating powder is a core-shell particle composed of rutile titanium dioxide and nano-antimony-doped tin dioxide, and is treated with a silica / zirconia coating and an organic compatibility layer. The modified organosilicon hydrophobic agent contains phosphonate esters and fluorinated segments, which can form a stable anchoring layer with the powder surface. Through the synergistic effect of the reflective heat-insulating powder and the organosilicon hydrophobic agent, this coating achieves high near-infrared reflectivity and durable hydrophobicity, significantly improving the reflectivity retention rate and water contact angle of the coating film under ultraviolet aging and acid rain cycling conditions. It possesses excellent comprehensive performance in terms of heat insulation, waterproofing, anti-fouling, and storage stability.

Description

Technical Field

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

[0002] With increasing demands for building energy efficiency and the promotion of green and environmentally friendly concepts, higher requirements are being placed on the performance of functional coatings for building exterior walls and roofs. Traditional reflective heat-insulating coatings mainly rely on high-reflectivity pigments and fillers to reduce solar radiation heat absorption. However, during long-term use, dust, oil, and biological deposits easily accumulate on the coating surface, leading to a significant decrease in near-infrared reflectivity and thus weakening the heat insulation performance. Once the coating becomes contaminated, it also increases the frequency and cost of cleaning and maintenance, which is detrimental to maintaining long-term energy-saving effects.

[0003] Meanwhile, conventional waterproof coatings or water-repellent treatments are easily affected by factors such as ultraviolet radiation, acid rain, and temperature and humidity cycles in outdoor exposure environments, leading to performance degradation. Water-repellent agents may migrate and be lost, making it difficult to maintain the waterproof effect in the long term. When defects such as microcracks and pinholes appear on the coating surface, rainwater can seep in along these defects, causing problems such as substrate weathering and coating peeling, thus shortening the service life.

[0004] Furthermore, to achieve high reflectivity and heat insulation effects, coatings typically require a high proportion of inorganic pigments and fillers. This can easily lead to difficulties in controlling the system viscosity, poor storage stability, filler sedimentation, or color floating and blooming, and may also affect the leveling properties and film uniformity during application. In harsh environments such as high humidity, acid and alkali conditions, or salt spray, some inorganic pigments also exhibit insufficient weather resistance and high surface reactivity, thereby accelerating coating aging and reducing heat insulation and protective performance.

[0005] Therefore, how to ensure the durability of high reflectivity, stable waterproof performance, and good construction and storage stability of reflective heat insulation coatings during long-term outdoor use remains an urgent problem to be solved. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a self-cleaning reflective heat-insulating and waterproof coating and its preparation method.

[0007] To achieve the above objectives, the first aspect of the present invention provides a self-cleaning reflective heat-insulating and waterproof coating, comprising the following components in parts by weight:

[0008] Deionized water: 6.4–6.6 parts;

[0009] Adhesive: 43-46 parts;

[0010] Dispersant: 0.4–0.6 parts;

[0011] Reflective heat insulation powder: 8-10 parts;

[0012] Wollastonite: 8-10 parts;

[0013] Precipitated barium sulfate: 25 parts;

[0014] Modified organosilicon water-repellent agent: 2-4 parts;

[0015] Associative thickener: 0.2–0.3 parts;

[0016] The reflective heat-insulating powder is a core-shell structured particle composed of rutile titanium dioxide and nano-antimony-doped tin dioxide in a mass ratio of 1.3 to 1.7:1.

[0017] Preferably, the reflective heat-insulating powder is prepared through the following steps:

[0018] (1) Disperse rutile titanium dioxide in deionized water to obtain a dispersion with a solid content of 30-40%, and adjust the pH to 7.5-8.0;

[0019] (2) Prepare a precursor solution of antimony-doped tin oxide and add it dropwise to the dispersion in step (1). At the same time, adjust the pH of the system to 8.5-9.0 so that tin oxide / antimony oxide hydrate is deposited in situ on the surface of titanium dioxide particles.

[0020] (3) The reflective heat insulation powder is obtained after aging treatment, solid-liquid separation, washing, drying, calcination and sieving.

[0021] Preferably, the preparation step of the reflective heat-insulating powder further includes the following step (4):

[0022] The particles obtained in step (3) were sequentially coated with a silica / zirconia composite coating and then sprayed with an organic compatibility layer composed of aminopropylsilane and epoxysilane; subsequently dried and sieved to obtain reflective heat insulation powder.

[0023] Preferably, the mass ratio of silicon dioxide to zirconium oxide is 3:1, and the mass ratio of aminopropylsilane to epoxysilane is 1:0.8 to 1.2.

[0024] Preferably, the reflective heat-insulating powder retains a near-infrared reflectance of not less than 85% in the 780–2500 nm wavelength band.

[0025] Preferably, the particle size distribution D of the reflective heat-insulating powder is... 90 Smaller than 0.8 μm and with a specific surface area of ​​6–10 m² 2 / g.

[0026] Preferably, the modified organosilicon hydrophobic agent comprises the following components by weight percentage:

[0027] Methyltrimethoxysilane: 12-18%;

[0028] octyltriethoxysilane: 6–10%;

[0029] 3-(trihydroxysilyl)propylmethylphosphonate: 5–9%;

[0030] Fluoroalkyltriethoxysilanes: 0.5–1.5%;

[0031] Polyether-modified polydimethylsiloxane: 2-4%;

[0032] Water and alcohol solvents: balance.

[0033] Preferably, the preparation method of the modified organosilicon hydrophobic agent includes the following steps:

[0034] A. Acid-catalyzed hydrolysis and condensation of methyltrimethoxysilane and n-octyltriethoxysilane in an alcohol-water mixture;

[0035] B. Add 3-(trihydroxysilyl)propylmethylphosphonate to the solution obtained in step A to introduce P=O functional groups during the condensation process;

[0036] C. Add fluoroalkyltriethoxysilane and polyether-modified polydimethylsiloxane, stir to emulsify evenly, and obtain modified organosilicon hydrophobic agent after aging.

[0037] A second aspect of the present invention provides a method for preparing the self-cleaning reflective heat-insulating and waterproof coating as described above, comprising the following steps:

[0038] S1. Dispersion: Add deionized water and dispersant to the dispersion tank, start high-speed dispersion, and add reflective heat insulation powder, wollastonite and precipitated barium sulfate in sequence until the system is uniformly dispersed;

[0039] S2. Mixing: Add binder to the dispersion slurry obtained in step S1 and mix evenly under low-speed stirring conditions;

[0040] S3. Add functional components: Add the modified organosilicon hydrophobic agent and the associative thickener to the system in step S2 in sequence, and stir until completely uniform to obtain a self-cleaning reflective heat-insulating and waterproof coating.

[0041] Preferably, the dispersion of the reflective heat-insulating powder in step S1 includes:

[0042] Add the reflective heat-insulating powder to the dispersion system under alkaline conditions of pH 8.0–9.0 and keep stirring for 30–40 minutes.

[0043] Compared with the prior art, the beneficial effects of the present invention are mainly reflected in the following aspects:

[0044] 1. This invention constructs core-shell structured particles by combining rutile titanium dioxide and antimony-doped tin dioxide in a specific mass ratio, and further treats them with silica / zirconia inorganic coating and an aminopropylsilane-epoxysilane organic compatibility layer. This allows the reflective heat-insulating powder to maintain a high and stable reflectivity in the 780–2500 nm wavelength range. Especially under ultraviolet aging and acid rain cycling conditions, the reflectivity retention rate is not less than 85%, effectively avoiding the performance degradation caused by surface reactions or agglomeration of traditional heat-insulating pigments during long-term use.

[0045] 2. By introducing modified organosilicon hydrophobic agents containing phosphonate groups and fluorinated segments into the coating, the hydrophobic agent not only constructs a low surface energy layer on the coating surface, but also forms a stable coordination anchor with metal ions on the surface of the reflective heat-insulating powder through P=O groups. This design effectively inhibits the migration and loss of hydrophobic components, enabling the coating film to maintain a contact angle ≥105° for a long time under outdoor exposure conditions, while also possessing anti-fouling and acid rain resistance properties, thus extending the service life of the coating.

[0046] 3. In the preparation method, the reflective heat-insulating powder is pre-dispersed under alkaline conditions of pH 8.0–9.0 and stirred for 30–40 minutes to ensure full hydration of the powder surface coating, thereby enhancing the interfacial bonding with the binder. This process significantly improves the dispersibility of the powder in the aqueous system, reduces the risk of sedimentation, floating color, and blooming, thus improving the storage stability and leveling properties of the coating. Attached Figure Description

[0047] Figure 1 This is a comparison of the reflectance curves of Example 1 and Comparative Example 1 in their initial state and after UV aging for 500 hours; where the horizontal axis represents wavelength (nm) and the vertical axis represents near-infrared reflectance (%). Detailed Implementation

[0048] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0049] Unless otherwise defined, all scientific and technical terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art.

[0050] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0051] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0052] The present invention will now be described in detail with reference to specific embodiments, which are intended to understand rather than limit the invention.

[0053] Without affecting the essential effects of the present invention, those skilled in the art may add commonly used auxiliary components to the formulation as needed, such as defoamers, pH adjusters, antifreeze agents and bactericides in the following examples. These components are not essential components of the present invention, and their main function is to improve the stability of the system or the construction performance, without changing the synergistic mechanism between the core components of the present invention.

[0054] Example 1

[0055] This embodiment provides a self-cleaning, reflective, heat-insulating, and waterproof coating, the components of which are in parts by weight as follows:

[0056] 6.5 parts deionized water;

[0057] 45 parts adhesive;

[0058] 0.5 parts dispersant;

[0059] 9 parts of reflective heat insulation powder;

[0060] 9 parts of wollastonite;

[0061] Precipitate 25 parts of barium sulfate;

[0062] 3 parts of modified organosilicon hydrophobic agent;

[0063] 0.25 parts of associative thickener.

[0064] The reflective heat-insulating powder is prepared from rutile titanium dioxide and antimony-doped tin dioxide in a mass ratio of 1.5:1, and the specific steps are as follows:

[0065] (1) The particle size D 50 It has a thickness of 0.25 μm and a specific surface area of ​​8.5 m². 2 / g of rutile titanium dioxide (R-TiO2) with a rutile content ≥98% was dispersed in deionized water to obtain a dispersion with a solid content of 30%. 0.5wt% of polycarboxylic acid dispersant (based on TiO2 solids, model PCE-45, solid content 40%) was added, and the pH was adjusted to 8.0 with 0.1mol / L NaOH solution. The mixture was stirred evenly.

[0066] (2) Preparation of antimony-doped tin oxide precursor solution: Take SnCl4·5H2O and potassium antimony tartrate and dissolve them in deionized water, control Sb / (Sn+Sb)=7at%, and add them dropwise to the dispersion obtained in step (1) at 50℃. At the same time, adjust the pH of the system with 25% ammonia water and slowly raise it to 8.8 (rate 0.05pH / min).

[0067] (3) After aging for 1 hour, the solid and liquid were separated and washed with deionized water until the chloride ion content in the filtrate was less than 100 ppm. After drying, the filtrate was calcined at 580℃ for 1 hour (heating rate 5℃ / min), cooled and passed through a 325-mesh sieve to obtain TiO2 / ATO core-shell particles.

[0068] (4) The above particles were dispersed in a silica / zirconium oxide sol (pH=9.0, SiO2 solid content 20%, ZrO2 solid content 5%, prepared by hydrolysis of tetraethoxysilane and zirconium nitrate), with a SiO2 to ZrO2 mass ratio of 3:1. The sol was stirred at 40℃ for 1 h for composite coating. After curing, an organic compatibility layer composed of 3-aminopropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane in a mass ratio of 1:1 was sprayed onto the particle surface. The particles were then dried and sieved to D. 90 <0.6μm, the reflective heat insulation powder product is obtained.

[0069] The modified organosilicon hydrophobic agent is composed of the following weight percentages:

[0070] 15% methyltrimethoxysilane;

[0071] 8% n-Octyltriethoxysilane;

[0072] 7% 3-(trihydroxysilyl)propyl methylphosphonate;

[0073] 0.8% fluoroalkyltriethoxysilane;

[0074] 3% polyether-modified polydimethylsiloxane;

[0075] The remaining amount of water and alcohol solvents (the alcohols are a 1:1 mixture of anhydrous ethanol and isopropanol).

[0076] The preparation steps of the modified organosilicon hydrophobic agent are as follows:

[0077] A. Adjust the pH to 4.5 in an alcohol-water mixture, add methyltrimethoxysilane and n-octyltriethoxysilane, and stir at 25°C for 40 minutes to hydrolyze;

[0078] B. Add 3-(trihydroxysilyl)propylmethylphosphonate to the solution obtained in step A, and continue stirring for 30 minutes;

[0079] C. Add fluoroalkyltriethoxysilane and polyether-modified polydimethylsiloxane, stir to emulsify evenly, mature for 1 hour, filter to remove impurities and obtain the finished product.

[0080] The associative thickener comprises the following parts by weight:

[0081] 70 parts of polyurethane oligomers with C16 hydrophobic end caps (number average molecular weight 3000, viscosity average molecular weight distribution coefficient <1.2); 25 parts of a mixture of propylene glycol methyl ether and dipropylene glycol in a 1:1 mass ratio.

[0082] The preparation method of the coating is as follows:

[0083] S1. Dispersion: Add deionized water and dispersant to the dispersion tank, start high-speed dispersion (1500 rpm), and then add reflective heat insulation powder and wollastonite (particle size D) in sequence. 50 =4μm, whiteness ≥90) and precipitated barium sulfate (particle size D) 50 =1μm, specific gravity 4.5), keep pH at 8.0 and stir continuously for 35 minutes to fully hydrate and evenly disperse the surface coating of the reflective heat insulation powder;

[0084] S2. Mixing: Add styrene-acrylic polymer emulsion binder to the slurry obtained in step S1, and stir at low speed of 500 rpm for 15 minutes until uniform;

[0085] S3. Add functional components: Add the modified organosilicon hydrophobic agent and the associative thickener in sequence, and stir slowly at 300 rpm for 10 minutes to obtain the finished coating.

[0086] Example 2

[0087] This embodiment is basically the same as Embodiment 1, except for the coating ratio of reflective heat insulation powder:

[0088] In step (4), TiO2 / ATO core-shell particles are dispersed in SiO2 / ZrO2 sol, and the mass ratio of SiO2 to ZrO2 is adjusted to 2.5:1, while the other conditions remain unchanged.

[0089] Example 3

[0090] This embodiment is basically the same as Embodiment 1, except for the proportion of the organic compatibility layer:

[0091] In step (4), when spraying the organic compatibility layer, the mass ratio of 3-aminopropyltriethoxysilane to γ-glycidoxypropyltrimethoxysilane is 1:1.2.

[0092] Comparative Example 1

[0093] Similar to Example 1, except that step (4) is omitted in the preparation of reflective heat insulation powder, that is, SiO2 / ZrO2 composite coating and organic compatibility layer treatment are not performed, and only TiO2 / ATO core-shell particles are obtained.

[0094] Comparative Example 2

[0095] Similar to Example 1, except that the reflective heat insulation powder is only coated with SiO2 / ZrO2 composite, and no organic compatibility layer of aminopropylsilane and epoxysilane is sprayed.

[0096] Comparative Example 3

[0097] Similar to Example 1, except that the reflective heat insulation powder is composed of rutile TiO2 and nano ATO in a mass ratio of 1:1.

[0098] This embodiment is the same as Example 1, except for the formulation of the modified organosilicon hydrophobic agent:

[0099] 15% methyltrimethoxysilane;

[0100] 8% n-Octyltriethoxysilane;

[0101] 3-(trihydroxysilyl)propyl methylphosphonate 9%;

[0102] 0.8% fluoroalkyltriethoxysilane;

[0103] 3% polyether-modified polydimethylsiloxane;

[0104] The remaining amount of water and alcohol solvents.

[0105] Example 5

[0106] This embodiment is the same as Example 1, except that the preparation order of the modified organosilicon hydrophobic agent is as follows:

[0107] After pre-hydrolysis in step A, 3-(trihydroxysilyl)propyl methylphosphonate is added first, followed by fluoroalkyltriethoxysilane, and finally polyether-modified polydimethylsiloxane.

[0108] Comparative Example 4

[0109] Similar to Example 1, except that the modified organosilicon hydrophobic agent formulation does not contain 3-(trihydroxysilyl)propylmethylphosphonate.

[0110] Comparative Example 5

[0111] Similar to Example 1, except that the phosphonate in the modified organosilicon hydrophobic agent is replaced by an equimolar amount of KH-550 (3-aminopropyltriethoxysilane).

[0112] Comparative Example 6

[0113] Similar to Example 1, except that the modified organosilicon hydrophobic agent formulation does not contain fluoroalkyltriethoxysilane.

[0114] Detection performance

[0115] 1. Near-infrared reflectance and retention

[0116] Test samples: film-forming samples of Examples 1-5 and Comparative Examples 1-6.

[0117] Instruments and methods: Initial reflectance was measured using an integrating sphere spectrophotometer (test wavelength 780-2500 nm);

[0118] UV aging test: Xenon lamp aging chamber (GB / T 1865-2009), after aging for 500h, the reflectance is measured again and the retention rate is calculated;

[0119] Acid rain cycle test: Spray with a dilute sulfuric acid solution of pH=4.0 10 times (10 min each time, followed by 50 min of drying), then measure the reflectance and calculate the retention rate.

[0120] 2. Water contact angle

[0121] Test samples: film-forming samples of Examples 1-5 and Comparative Examples 1-6.

[0122] Instruments and methods: Contact angle measuring instrument (droplet volume 5μL) was used to measure the initial contact angle and the contact angle after 500h of UV aging. Five points were tested for each sample and the average value was taken.

[0123] 3. Powder particle size distribution D 90

[0124] Test samples: reflective heat-insulating powders prepared in Examples 1-5 and Comparative Examples 1-6.

[0125] Instruments and methods: Laser particle size analyzer was used for testing. The dispersion medium was deionized water. The mixture was sonicated for 3 minutes, and the D value was read. 90 value.

[0126] 4. Storage stability

[0127] Test samples: Coating slurries obtained from Examples 1-5 and Comparative Examples 1-6.

[0128] Method: The samples were placed at 25±2℃ and allowed to stand for 30 days. The height of the settling layer (mm / 30d) was measured using the graduated cylinder method. At the same time, the presence of obvious stratification and flocculation was observed.

[0129] 5. Fineness

[0130] Test samples: Coating slurries obtained from Examples 1-5 and Comparative Examples 1-6.

[0131] Instruments and methods: The scraper fineness gauge was used for testing, with the unit being μm. The reading was taken at the point where there were no continuous particle traces.

[0132] 6. KU viscosity

[0133] Test samples: Coating slurries obtained from Examples 1-5 and Comparative Examples 1-6.

[0134] Method: KU value was measured at 25℃ using a Stormer KU viscometer.

[0135] 7. Adhesion

[0136] Test samples: film-forming samples of Examples 1-5 and Comparative Examples 1-6.

[0137] Method: According to GB / T 9286-1998 "Cross-cut test of paint and varnish film", the film was peeled off with tape after cross-cutting, and rated from 0 to 5.

[0138] 8. Scrub resistance

[0139] Test samples: film-forming samples of Examples 1-5 and Comparative Examples 1-6.

[0140] Method: Refer to GB / T 9266-2009 "Test Method for Scrub Resistance of Architectural Coatings" and record the number of cycles until the substrate is exposed or a significant color difference appears.

[0141] The above test results are shown in Table 1 below. Figure 1 As shown:

[0142] Table 1

[0143] Powder D90 (μm) 0.6 0.65 0.58 0.6 0.6 0.82 0.74 0.7 0.6 0.61 0.6 Initial NIR reflectance (%) 88.5 88 89.2 88.7 88.9 86 87 87.2 87.5 87.8 87.6 UV 500h retention rate (%) 87 86 88 88 89 73 78 79 78 80 81 Acid rain retention rate after 10 exposures (%) 86.2 85.3 88.1 87.5 88.4 75.2 78.5 80.1 79.2 81 81.5 Initial contact angle (°) 108 107 109 109 110 99 101 102 100 101 99 Contact angle after aging (°) 106 105 107 107 108 92 94 95 95 96 93 Storage settling (mm / 30d) 1 2 1 1 0 6 4 3 3 2 2 Fineness (μm) 30 32 28 30 29 38 35 34 31 31 31 Viscosity (KU) 92 93 94 92 93 90 91 91 92 92 92 Adhesion (Grade) 0 0 0 0 0 2 1 1 1 1 1 Washable (number of washes) 2200 2150 2300 2250 2350 1600 1850 1800 1750 1820 1780

[0144] Figure 1 Curve A is the near-infrared reflectance curve of Example 1 in its initial state; curve B is the near-infrared reflectance curve of Example 1 after UV aging for 500 h; curve C is the near-infrared reflectance curve of Comparative Example 1 in its initial state; and curve D is the near-infrared reflectance curve of Comparative Example 1 after UV aging for 500 h.

[0145] Conclusion: Compared with Comparative Example 1, which did not undergo inorganic / organic double-layer coating, the reflectance retention rate of Example 1 increased from 73% to 87% after 500 h of UV exposure, and the water contact angle increased from 92° to 106°, indicating that the composite coating and compatibility layer can significantly inhibit powder agglomeration and interfacial degradation.

[0146] Removing phosphonates from the hydrophobic agent (Comparative Example 4) or replacing them with KH-550 (Comparative Example 5) reduced the UV500 h reflectance retention to 78% and 80%, respectively, and the contact angle to 95–96°, demonstrating that the coordination anchoring effect of phosphonates is crucial for optical stability and durable hydrophobicity.

[0147] During the dispersion stage, the pH was controlled at 8–9 and the mixture was stirred for 30–40 min (see Examples 1 and 5). The sedimentation of the samples during storage was reduced to 0–1 mm / 30 d, which was a significant advantage compared to the control sample with unoptimized dispersion (3–6 mm / 30 d).

[0148] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A self-cleaning, reflective, heat-insulating, and waterproof coating, characterized in that, The components include the following parts by weight: Deionized water: 6.4–6.6 parts; Adhesive: 43-46 parts; Dispersant: 0.4–0.6 parts; Reflective heat insulation powder: 8-10 parts; Wollastonite: 8-10 parts; Precipitated barium sulfate: 25 parts; Modified organosilicon water-repellent agent: 2-4 parts; Associative thickener: 0.2–0.3 parts; The reflective heat-insulating powder is a core-shell structured particle composed of rutile titanium dioxide and nano-antimony-doped tin dioxide in a mass ratio of 1.3 to 1.7:

1. The reflective heat-insulating powder is prepared through the following steps: (1) Disperse rutile titanium dioxide in deionized water to obtain a dispersion with a solid content of 30-40%, and adjust the pH to 7.5-8.0; (2) Prepare a precursor solution of antimony-doped tin oxide and add it dropwise to the dispersion in step (1). At the same time, adjust the pH of the system to 8.5-9.0 so that tin oxide / antimony oxide hydrate is deposited in situ on the surface of titanium dioxide particles. (3) After aging treatment, solid-liquid separation, washing, drying, calcination and sieving; (4) The particles obtained in step (3) are sequentially coated with silica / zirconia composite and sprayed with an organic compatibility layer composed of aminopropylsilane and epoxysilane; then dried and sieved to obtain reflective heat insulation powder; The modified organosilicon hydrophobic agent comprises the following components by weight percentage: Methyltrimethoxysilane: 12-18%; octyltriethoxysilane: 6-10%; 3-(trihydroxysilyl)propylmethylphosphonate: 5-9%; Fluoroalkyltriethoxysilanes: 0.5–1.5%; Polyether-modified polydimethylsiloxane: 2-4%; Water and alcohol solvents: balance.

2. The self-cleaning, reflective, thermal barrier, water repellent coating according to claim 1, characterized in that, The mass ratio of silicon dioxide to zirconium oxide is 3:1, and the mass ratio of aminopropylsilane to epoxysilane is 1:0.8 to 1.

2.

3. The self-cleaning, reflective, thermal barrier, water repellent coating according to claim 1, wherein, The reflective heat insulation powder retains a near-infrared reflectance of no less than 85% in the 780–2500 nm wavelength band.

4. The self-cleaning, reflective, thermal barrier, water repellent coating according to claim 1, wherein, The particle size distribution D of the reflective heat insulation powder 90 Smaller than 0.8 μm and with a specific surface area of ​​6–10 m² 2 / g.

5. The self-cleaning reflective heat-insulating and waterproof coating according to claim 1, characterized in that, The preparation method of the modified organosilicon hydrophobic agent includes the following steps: A. Acid-catalyzed hydrolysis and condensation of methyltrimethoxysilane and n-octyltriethoxysilane in an alcohol-water mixture; B. Add 3-(trihydroxysilyl)propylmethylphosphonate to the solution obtained in step A to introduce P=O functional groups during the condensation process; C. Add fluoroalkyltriethoxysilane and polyether-modified polydimethylsiloxane, stir to emulsify evenly, and obtain the modified organosilicon hydrophobic agent after aging.

6. A method for preparing a self-cleaning reflective heat-insulating and waterproof coating according to any one of claims 1 to 5, characterized in that, Includes the following steps: S1. Dispersion: Add deionized water and dispersant to the dispersion tank, start high-speed dispersion, and add reflective heat insulation powder, wollastonite and precipitated barium sulfate in sequence until the system is uniformly dispersed; S2. Mixing: Add binder to the dispersion slurry obtained in step S1 and mix evenly under low-speed stirring conditions; S3. Add functional components: Add the modified organosilicon hydrophobic agent and the associative thickener to the system in step S2 in sequence, and stir until completely uniform to obtain a self-cleaning reflective heat-insulating and waterproof coating.

7. The method for preparing a self-cleaning reflective heat-insulating and waterproof coating according to claim 6, characterized in that, The dispersion of the reflective heat-insulating powder in step S1 includes: The reflective thermal insulation powder is added to the dispersion system under alkaline conditions of pH 8.0-9.0, and stirring is maintained for 30-40 minutes.

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