Waterproof weather-resistant exterior wall paint and preparation method thereof

Abstract

The invention discloses waterproof and weather-resistant exterior wall paint and a preparation method, and particularly relates to the technical field of building coatings, the core of the waterproof and weather-resistant exterior wall paint is that a geopolymer is used as a matrix, and a bionic protection technology and an intelligent color development technology are combined to realize excellent waterproofness, weather resistance and color stability. The exterior wall paint mainly comprises a geopolymer matrix, a bionic protection system, a color development system and a functional auxiliary agent. Wherein the geopolymer matrix is composed of activated fly ash, acid-washed calcined red mud and other materials, a compact three-dimensional network structure is formed, and the waterproof performance and weather resistance of the coating are remarkably improved; the bionic protection system realizes the super-hydrophobic characteristic through gradient coating of diatomite and other materials, and the self-cleaning efficiency is remarkably improved. The coating is prepared from natural inorganic mineral raw materials, is safe, harmless, pollution-free, green and environment-friendly, is suitable for high-cold, high-temperature, high-humidity, strong-ultraviolet and severe-pollution areas, and is cold-resistant, heat-resistant, crack-resistant, frost-resistant, waterproof, moisture-proof, acid-resistant, alkali-resistant, washing-resistant and stain-resistant.

Description

Technical Field

[0001] The present invention relates to the technical field of architectural coatings, and particularly relates to a waterproof and weather-resistant exterior wall paint and a preparation method thereof. Background Art

[0002] Traditional exterior wall paints generally have problems such as poor weather resistance, easy fading, and insufficient waterproof performance. Especially in high-temperature, high-humidity, or strong ultraviolet light environments, the coating is prone to cracking, powdering, water seepage, etc., resulting in a shortened service life. In the prior art, some coatings improve weather resistance by adding silicone or fluorocarbon resin, but the cost is high and the environmental friendliness is poor; others use inorganic mineral fillers to improve waterproofness, but it is difficult to take into account the color display stability. In addition, the conventional color display system relies on organic pigments and is easily degraded by ultraviolet light, with insufficient color persistence.

[0003] Therefore, it is urgent to develop an exterior wall paint based on geopolymers, combined with bionic protection and intelligent color display technologies, to achieve long-term waterproofing, weather resistance, and color stability on the basis of low cost and environmental friendliness. Summary of the Invention

[0004] The main purpose of the present invention is to provide a waterproof and weather-resistant exterior wall paint and a preparation method thereof. Through the synergistic effect of the geopolymer matrix and the bionic protection system, combined with intelligent color display technology, the problems of poor weather resistance, insufficient waterproof performance, and easy color fading of traditional coatings are solved.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] A waterproof and weather-resistant exterior wall paint, comprising:

[0007] a. Geopolymer matrix: including 280 - 320 parts of activated fly ash, 70 - 90 parts of pickled calcined red mud, 140 - 160 parts of calcium silicate magnesium composite activator, 60 - 80 parts of modified glass microspheres, and 12 - 25 parts of magnesium fluorosilicate crystal nucleus inducer;

[0008] b. Bionic protection system: including 110 - 130 parts of gradient-coated diatomite, 55 - 65 parts of potassium silicate whiskers derived from straw ash, and 75 - 85 parts of mica iron oxide;

[0009] c. Color display system: including 85 - 95 parts of colored sand, 25 - 35 parts of microencapsulated iron oxide pigment, and 8 - 12 parts of inorganic hydrated salt phase change color display agent;

[0010] d. Functional additives: 20 - 30 parts of polycarboxylate dispersant and 15 - 25 parts of polyurethane thickener.

[0011] Preferably, in the geopolymer matrix:

[0012] The specific preparation method of activated fly ash is as follows: Select fly ash with SiO2 + Al2O3 ≥ 75% from a thermal power plant, and activate it by zirconia ball milling. The ball milling parameters are: the diameter of zirconia grinding balls is 10 mm, the ball-to-material ratio is 10:1, and ball milling is carried out at 45 rpm for 4 h under nitrogen protection; then, atomize and treat it with 5% dilute sulfuric acid at a liquid-to-solid ratio of 0.3:1, age it at 60 °C for 24 h, wash it with water until neutral, and dry it to obtain the activated fly ash;

[0013] The specific method of pickling and calcining red mud is as follows: Dynamically leach the red mud with 10% hydrochloric acid. The dynamic leaching parameters are: the solid-to-liquid ratio is 1:5, 200 rpm × 2 h. After pressure filtration, stage calcine it (150 °C → 350 °C → 650 °C), and crush it to D50 = 15 μm to obtain red-brown fine powder for standby;

[0014] The specific preparation method of modified glass microspheres is as follows: Select waste gas glass, wash it, and crush it into glass microsphere particles with a particle size of 20 - 30 μm. Then, etch it with 40% HF for 30 s and wash it with water, and then spray it with a silane coupling agent KH-550 ethanol solution (2 wt%) for surface modification. Then, dry it at 120 °C to obtain the modified glass microspheres.

[0015] The silicon-calcium-magnesium composite activator is specifically: Sodium silicate with a modulus of 2.1 and a solid content of 40%, slaked lime with Ca(OH)2 ≥ 95%, and magnesium sulfate heptahydrate with MgSO4·7H2O ≥ 99% are sequentially added to a 60 °C water bath, control the end point pH = 12.5 ± 0.3, and the viscosity at room temperature ≤ 500 cP to obtain the silicon-calcium-magnesium composite activator.

[0016] Preferably, in the bionic protection system:

[0017] The specific preparation method of gradient-coated diatomite is as follows: Select diatomite and mix it with Ca(OH)2 at a volume ratio of 3:1, pass CO2 until pH = 7 to generate a CaCO3 core, and then deposit a nano-SiO2 shell layer by the sol-gel method. After centrifugal separation, dry it at 120 °C to obtain a core-shell structured powder, which is the gradient-coated diatomite;

[0018] The method for obtaining potassium silicate whiskers derived from straw ash is as follows: Mix rice straw ash and quartz sand at a volume ratio of 1:2, melt it at 1450 °C, then cool it at a rate of 10 °C / min to 800 °C and hold for 2 h to grow whiskers, and then ultrasonically treat it with 5% nitric acid for 1 h to obtain potassium silicate whiskers with an aspect ratio > 20.

[0019] Preferably, in the color display system:

[0020] The preparation method of the microencapsulated iron oxide pigment is as follows: The iron oxide red is soaked in 5% dilute hydrochloric acid for 30 minutes at a solid-liquid ratio of 1:10. Subsequently, tetraethyl orthosilicate, ethanol, and water are mixed in a volume ratio of 1:8:4 to prepare a sol. At the same time, under the condition of pH 9-10, iron oxide is dispersed in ammonia water / ethanol / water = 5:1:1 to form a suspension; The tetraethyl orthosilicate sol is slowly added dropwise and stirred in a 60°C water bath for 6 hours to uniformly coat the iron oxide particles with SiO2. After centrifugation, ethanol washing, and drying at 60°C, finally, it is calcined at 400°C for 2 hours to obtain a core-shell structure powder;

[0021] The preparation method of the inorganic hydrated salt phase change color developer is as follows: It is dissolved at 40°C and slowly crystallized at 5°C, and then undergoes ethanol washing and vacuum drying treatment to obtain recrystallized and purified sodium sulfate decahydrate; A composite nucleating agent composed of borax and nano-TiO2 in a ratio of 1:1 is added to inhibit supercooling; Subsequently, it is ultrasonically compounded in a molten state at 50°C to form loose particles with a salt absorption rate ≥ 90%; A poly(methyl methacrylate) with a molecular weight of about 50,000 is formulated into a 10 wt% ethyl acetate oil-phase solution and 0.5% sorbitan monooleate is added, and it is mixed with a 1% sodium dodecyl sulfate aqueous solution containing a 20% solid content phase change composite in a volume ratio of 1:4, and emulsified by high-speed shearing at 10000 rpm for 5 minutes to form a stable W / O emulsion. Then, the solvent is stirred and volatilized at 40°C for 6 hours, and finally, a microcapsule product with a particle size distribution of 50-150 μm and a coating rate exceeding 95% is prepared.

[0022] Preferably, the viscosity of the polyurethane thickener at 25°C is 2000-3000 cP, and the mass ratio with the polycarboxylate dispersant is 1:1.5.

[0023] The present invention also discloses a method for preparing the above waterproof and weather-resistant exterior wall paint, which includes the following steps:

[0024] Step 1, preparation of the geopolymer matrix: Activated fly ash and red mud are added to a high-speed mixer and premixed at 200 rpm for 10 min; The calcium silicate magnesium activator is added in 3 batches (with an interval of 15 min), and the temperature is raised to 60°C and reacted for 30 min; Magnesium fluorosilicate and acid-etched glass microspheres are added, and mixed at a low speed of 60 rpm for 30 min;

[0025] Step 2, compounding of the bionic protection system: Gradient-coated diatomite, potassium silicate whiskers derived from straw ash, and mica iron oxide are mixed in proportion, ball-milled to D50 = 20-30 μm, and mixed with the matrix obtained in step (1);

[0026] Step 3, dispersion of the color display system: Colored sand, microencapsulated iron oxide pigment, and inorganic hydrated salt phase change color developer are added to a sand mill and dispersed at 1500 rpm for 30 minutes to form a uniform color paste;

[0027] Step 4, functional additive preparation: add polycarboxylate dispersant and polyurethane thickener to the color paste of step 3, and mix at low speed (200-300 rpm) for 10 minutes;

[0028] Step 5, finished product mixing: Mix the materials in step 2, step 3 and step 4 with mechanical stirring at 1000rpm for 40min, then process in a vacuum degasser for 20min, filter and package

[0029] Preferably, the stirring temperature of the high-speed mixer in step (1) is 40-50° C., and the viscosity of the mixed material is ≤800 cP.

[0030] Preferably, the ball milling in step (2) uses alumina grinding balls, the ball-to-material ratio is 5:1, and the ball milling time is 2-3 hours.

[0031] Preferably, the vacuum degree of vacuum degassing in step (5) is -0.08 to -0.1 MPa, and the solid content of the paint after degassing is ≥65%.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] 1. The geopolymer matrix of the present invention reacts with the activated aluminosilicate in activated fly ash and acid-washed calcined red mud through the reaction of the silicon-calcium-magnesium composite activator to form a dense [Si-O-Al] three-dimensional network structure, combined with the refinement effect of the magnesium fluorosilicate nucleus inducer, the porosity of the coating is reduced, and the waterproofness, weather resistance and color stability are improved; in the bionic protection system, the CaCO3 / SiO2 core-shell structure of the gradient-coated diatomaceous earth constructs a micro-nano rough surface, and the fiber toughening effect of the potassium silicate whiskers derived from straw ash is combined to give the coating a "lotus effect" super-hydrophobic property, which significantly improves the self-cleaning efficiency of rainwater scouring; mica iron oxide blocks the free radical chain reaction by reflecting ultraviolet rays, further improving the weather resistance.

[0034] 2. In the color development system of the present invention, the microencapsulated iron oxide pigment isolates moisture and ultraviolet rays through the SiO2 shell, thereby improving the color retention rate, and the inorganic hydrated salt phase change color developer can reversibly change phase between -20°C and 80°C, and realizes dynamic color development through changes in the lattice hydration state, thereby expanding the application of coatings in the field of temperature control indication of energy-saving buildings.

[0035] 3. In terms of environmental protection technology, the present invention uses fly ash, red mud and other industrial solid waste as the main raw materials, combines low-temperature calcination with the sol-gel method, reduces carbon emissions by 50%, and the whole formula does not release VOCs, meets the green building material standards, significantly reduces costs, and improves economic benefits. DETAILED DESCRIPTION

[0036] In order to make the technical means, creative features, achieved purposes and effects of the present invention easy to understand, the present invention will be further described below in conjunction with specific embodiments.

[0037] The present invention discloses a waterproof and weather-resistant exterior wall paint. At the beginning of the design concept, the main purpose is to avoid the formation of a coating film by the curing of the emulsion in traditional real stone paint, water-in-sand, water-in-water, and latex paint, and the surface activity after long-term rain immersion and frost, resulting in water absorption, swelling, softening, hardening and embrittlement of the epidermis, and deterioration of weather resistance. Therefore, the improvement of its weather resistance and water resistance is the key direction of the present invention; in addition, during the research process of the present invention, it is found that there are also exterior wall paints prepared from inorganic materials in the prior art, which rely on high-purity silicate, titanium dioxide and other raw materials, with high costs (such as the raw material cost of silica sol paint accounting for more than 60%), high energy consumption in the production process (such as silicate sintering at more than 1400 °C), single function, some inorganic coatings contain alkaline activators (pH > 13), with strong construction corrosion, some silicate coatings dry slowly (surface drying > 4 h), and multiple coatings are required.

[0038] Therefore, the inventor of the present invention proposes a waterproof and weather-resistant exterior wall paint. It includes the following components:

[0039] Geopolymer matrix: including 280 - 320 parts of activated fly ash, 70 - 90 parts of pickled and calcined red mud, 140 - 160 parts of calcium silicate magnesium composite activator, 60 - 80 parts of modified glass microspheres, and 12 - 25 parts of magnesium fluorosilicate crystal nucleus inducer;

[0040] Bionic protection system: including 110 - 130 parts of gradient-coated diatomite, 55 - 65 parts of potassium silicate whiskers derived from straw ash, and 75 - 85 parts of mica iron oxide;

[0041] Color display system: including 85 - 95 parts of colored sand, 25 - 35 parts of microencapsulated iron oxide pigment, and 8 - 12 parts of inorganic hydrated salt phase change color developer;

[0042] Functional additives: 20 - 30 parts of polycarboxylate dispersant and 15 - 25 parts of polyurethane thickener.

[0043] a. In the system of the geopolymer matrix:

[0044] Regarding activated fly ash:

[0045] Fly ash is an industrial by-product generated by coal combustion in thermal power plants, mainly composed of silicon dioxide (SiO2) and aluminum oxide (Al2O3). Fly ash with a content higher than 75% has good activation potential. The process of activation by zirconia ball milling can effectively improve the reaction activity and application performance of fly ash.

[0046] In the specific preparation process, fly ash meeting the composition requirements is first selected, and then ball milling is carried out using zirconia grinding balls. Ball milling grinds materials into finer particles through mechanical force to increase their specific surface area, thereby enhancing their reactivity with other materials. The diameter of the grinding balls is set at 10 mm, and the ball-to-material ratio is 10:1, which can ensure the effectiveness and uniformity of grinding. The rotation speed of the ball milling is 45 revolutions per minute, and it is carried out in a nitrogen protection environment, which can effectively prevent the occurrence of oxidation reactions and ensure the activation effect.

[0047] After ball milling, the fly ash is atomized with 5% dilute sulfuric acid, and the liquid-to-solid ratio is 0.3:1. The treatment with dilute sulfuric acid can further enhance the chemical activity of the fly ash and promote the dissolution and transformation of its silicon and aluminum components. It is aged at 60 °C for 24 hours at room temperature to allow it to react fully, and then washed with water to remove unreacted acid and impurities to ensure the neutrality of the fly ash.

[0048] Finally, the activated fly ash after drying can be used in fields such as cement, concrete, and civil engineering, significantly improving the mechanical properties and durability of materials. This preparation method not only improves the utilization rate of fly ash but also contributes to the recycling of resources, in line with the concept of sustainable development.

[0049] Regarding pickling and calcining red mud:

[0050] Red mud is an industrial waste generated during the extraction of aluminum oxide from bauxite, containing abundant metal elements such as iron, titanium, and aluminum. To effectively recover these useful metals and improve the environmental impact of red mud, a method combining pickling and calcining is used for treatment.

[0051] Specifically, in the pickling step, 10% hydrochloric acid is used for dynamic leaching of red mud. During this process, the solid-to-liquid ratio is set at 1:5, meaning 5 milliliters of hydrochloric acid solution is used for every 1 gram of red mud to ensure sufficient contact and dissolution of the reactants. In addition, stirring is carried out at a speed of 200 revolutions per minute during dynamic leaching, which can increase the fluidity of the solution, thereby accelerating the reaction between hydrochloric acid and the surface of red mud and enhancing the leaching efficiency of metal ions. After 2 hours of leaching, some metal oxides dissolve in hydrochloric acid to form corresponding metal chlorides.

[0052] After the leaching is completed, the leachate and solid residue are obtained through pressure filtration separation. Then the residue is subjected to calcination treatment. This step is divided into three stages. First, it is heated at 150 °C to remove moisture and organic matter; then the temperature is raised to 350 °C to promote chemical reactions and phase changes to form more stable compounds; finally, it is calcined at 650 °C to achieve the crystallization and mutual transformation of metal oxides, ultimately enhancing its physical and chemical properties.

[0053] The calcined solid material is crushed to D50 = 15 μm, which means the median particle size of the powder is 15 microns. The powder with moderate fineness is convenient for subsequent applications, such as being used as building materials, catalyst carriers or strengthening agents, etc. This series of treatment processes not only effectively recovers the useful components in the red mud, but also promotes its reuse, reduces the impact of industrial waste on the environment, and realizes the recycling of resources. The finally obtained reddish-brown fine powder can be used as a high-value industrial raw material, contributing to the development of the green economy.

[0054] Regarding the modified glass microspheres:

[0055] Modified glass microspheres are functional materials prepared from waste glass through a series of physical and chemical treatments, and are widely used in fields such as coatings, plastics and composite materials to improve the mechanical properties and weather resistance of materials. The following is a further description of the production process.

[0056] First, the waste glass is cleaned to remove the impurities, oil stains and pollutants attached to its surface, ensuring that the reaction effect is not affected during the subsequent treatment process. The cleaned glass is crushed and pulverized to a particle size in the range of 20 - 30 microns. The selection of this particle size enables the glass microspheres to have a larger specific surface area, thereby improving their binding ability and reaction activity with other materials.

[0057] Next, etching treatment is carried out with 40% hydrofluoric acid (HF). Hydrofluoric acid can effectively remove some amorphous silicon oxides on the glass surface, enhance its surface roughness, and thus increase its subsequent binding ability with functional chemical substances. The etching time is set to 30 seconds to ensure sufficient modification of the glass microsphere surface but avoid over-corrosion, so as to retain its original structural characteristics.

[0058] After the acid etching is completed, the glass microspheres are immediately washed with water to remove the generated fluorides and unreacted acid. This step is crucial, which can ensure the safety and stability of the final product.

[0059] Subsequently, the washed glass microspheres are spray-treated with 2 wt% of silane coupling agent KH-550 dissolved in ethanol. KH-550 is a commonly used silane coupling agent, which can form an organosilicon compound layer on the surface of the glass microspheres, improving their hydrophilicity and interfacial adhesion properties. Spray treatment can make the coupling agent evenly cover the surface of the microspheres, ensuring the effectiveness of chemical modification.

[0060] Finally, the modified glass microspheres are dried at 120 °C to remove excess solvent and allow the coupling agent to form strong covalent bonds on the surface of the microspheres. This process not only improves the chemical stability of the glass microspheres but also enhances their performance in various applications. After this series of treatments, the finally obtained modified glass microspheres can be used to improve the strength, temperature resistance of composite materials, as well as to improve their appearance and service life, providing high-quality new material options for various industrial applications.

[0061] Regarding the calcium-silicon-magnesium composite activator:

[0062] The calcium-silicon-magnesium composite activator is a chemical additive used to improve the properties of cement and concrete. Through the synergistic effect of composite silicate, calcium hydroxide, and magnesium sulfate, it can effectively enhance the strength and durability of the materials. Its preparation process mainly includes the reasonable proportioning and reaction control of several key components to ensure the stable performance of the final product.

[0063] In the preparation process, sodium silicate solution with a modulus of 2.1 and a solid content of 40% is first selected as the basic component. Sodium silicate can form a silicate solution in water, providing silicate ions for subsequent reactions and having good activation properties. The produced silicate ions can react with other components under certain conditions to form an overall structure, thereby enhancing the mechanical properties of the materials.

[0064] Next, slaked lime (Ca(OH)2) with a purity of over 95% is added. As a source of calcium hydroxide, slaked lime can effectively increase the alkaline environment of the system and provide the required calcium ions for the reaction to produce calcium hydroxide and other compounds. Controlling the pH value of the system within the range of 12.5 ± 0.3 is a key step to ensure the suitability of the reaction and the stability of the product. At this time, the high-pH environment helps the combination of silicate ions and calcium ions, thereby forming an organic calcium silicate hydrate gel.

[0065] In addition, magnesium sulfate heptahydrate (MgSO4·7H2O) is introduced with a purity of ≥99%. Magnesium sulfate heptahydrate can not only provide magnesium ions but also adjust the ionic strength of the solution, promoting the hydration and gelation process of the cementitious material. In terms of the mechanism of action, the addition of magnesium ions can form a composite structure with silicate ions and calcium ions, further enhancing the strength and toughness of the materials.

[0066] When integrating these components, they are introduced into a 60 °C water bath in sequence for thorough mixing. The heated water bath conditions can accelerate the reaction rate and ensure the completeness of the reaction. During this process, the viscosity should be continuously monitored to ensure that it does not exceed 500 cP at room temperature. This index helps to maintain the fluidity and construction convenience of the product.

[0067] Finally, the obtained calcium-silicon-magnesium composite activator will possess excellent physical and chemical properties and can be used as an additive in building materials such as cement and concrete. It can not only improve the strength and durability of materials but also reduce production costs, meet the requirements of sustainable development, and provide support for the research and development of new building materials.

[0068] b. In the bionic protection system:

[0069] Regarding gradient-coated diatomite: Gradient-coated diatomite is a new type of functional material. By forming a nanoscale silica (SiO2) shell layer on the surface of diatomite, its physical and chemical properties are improved, and its applicability in various application fields is enhanced. The preparation process of this material involves multiple-step reactions, including the mixing reaction of diatomite and calcium hydroxide, the introduction reaction of carbon dioxide, and the deposition by the sol-gel method.

[0070] First, diatomite and calcium hydroxide (Ca(OH)2) are mixed in a volume ratio of 3:1 to form a homogeneous mixture. Diatomite is a natural silicate mineral rich in silicon, with good adsorption properties and a large specific surface area, while calcium hydroxide provides a rich calcium source. In this mixture, calcium hydroxide can not only enhance the reactivity of diatomite but also react with the subsequently added carbon dioxide to form a calcium carbonate (CaCO2) core.

[0071] Next, carbon dioxide (CO2) is introduced into the mixture to adjust the pH value of the system to 7. In this process, the CO2 gas reacts with calcium hydroxide to promote the precipitation of calcium carbonate. The control of this stage is crucial because the change in pH value directly affects the formation of the core and the uniformity of the particle size. The finally formed CaCO3 core has good stability and rigidity, providing good support for the subsequent deposition of the SiO2 shell layer.

[0072] The next step is to deposit the nanoscale SiO2 shell layer by the sol-gel method. The sol-gel method is a well-established method for preparing nanomaterials, which can synthesize a uniform and fine silica coating at a relatively low temperature. In this process, a silica precursor sol is first prepared through a chemical reaction and then deposited on the surface of the CaCO3 core to form a uniform SiO2 shell. This shell effectively coats the core, enhancing its chemical stability, and at the same time can provide excellent mechanical strength and improve the thermal stability of the material.

[0073] Finally, the un-deposited silica precursors and other reactants are removed by centrifugation, and then dried at a temperature of 120 °C to remove moisture and volatile substances, completing the curing of the structure. The finally obtained gradient-coated diatomite not only has excellent structural properties, but also has good adsorption and biocompatibility, and is widely used in many fields such as environmental engineering, cosmetics, medicine, and building materials, meeting the requirements of different fields for material properties.

[0074] Regarding potassium silicate whiskers derived from straw ash:

[0075] First, rice straw ash and quartz sand are mixed at a volume ratio of 1:2. As a material rich in organic matter and minerals, rice straw ash mainly contains silicates, which is of great significance for the subsequent formation of potassium silicate whiskers. In this process, rice straw ash provides the required silicon source, while quartz sand provides abundant silicic acid components. Through a reasonable ratio, a good melting system is ensured at high temperature to promote the growth of whiskers.

[0076] Next, the mixture is melted at 1450 °C. High-temperature melting is a key step in whisker growth, which can transform the silicates in the raw materials into a melt, promoting the rearrangement and solid-phase transformation between reactants. During this process, the molten material forms a glassy state with good fluidity under the action of temperature, facilitating subsequent precipitation and crystallization.

[0077] After melting, the temperature is cooled to 800 °C at a rate of 10 °C / min and held for 2 hours to promote the growth of whiskers. Within this temperature range, the silicates in the melt crystallize through heat treatment to form a whisker-like potassium silicate structure. The control of this holding time is to ensure the formation and growth integrity of the whiskers, which is conducive to increasing their aspect ratio (i.e., the ratio of length to diameter). Potassium silicate whiskers with an aspect ratio greater than 20 have high strength and excellent properties, and are suitable for the reinforcement and functionalization applications of various materials.

[0078] After the whisker growth is completed, ultrasonic treatment is then carried out with 5% nitric acid for 1 hour. This treatment step not only helps to remove unreacted impurities and excess salts on the surface, but also can promote the dispersion of whiskers through the action of ultrasonic waves, improving their uniform distribution in the composite material. The ultrasonic energy reduces the interaction between particles, thus achieving efficient dispersion of the whiskers.

[0079] Finally, the obtained potassium silicate whiskers have excellent physical and chemical properties, such as high strength, high heat resistance, and good environmental adaptability. This gives them broad prospects in application fields such as plastic reinforcement, optical materials, coatings, and ceramics. In this way, rice straw ash as waste is effectively converted into a functional material with high value, promoting sustainable development and resource recycling.

[0080] c. In the color development system:

[0081] The preparation method of the microencapsulated iron oxide pigment is as follows:

[0082] The iron oxide red is soaked in 5% dilute hydrochloric acid for 30 minutes at a solid-liquid ratio of 1:10. Subsequently, tetraethyl orthosilicate, ethanol, and water are mixed in a volume ratio of 1:8:4 to prepare a sol. At the same time, under the condition of pH 9 - 10, the iron oxide is dispersed in ammonia water / ethanol / water = 5:1:1 to form a suspension; the tetraethyl orthosilicate sol is slowly added dropwise and stirred in a 60°C water bath for 6 hours to uniformly coat the iron oxide particles with SiO2. After centrifugation, ethanol washing, and drying at 60°C, finally, it is calcined at 400°C for 2 hours to obtain a core-shell structure powder;

[0083] Through the microencapsulation technology, the iron oxide pigment is coated in the silica shell layer, greatly improving its stability to the external environment and reducing the risk of pigment oxidation and fading. This is particularly important for industries such as coatings, plastics, and building materials, which is conducive to improving the service life and appearance quality of products;

[0084] The core-shell structure can not only improve the physical properties of the pigment but also enhance its adhesion and dispersibility in the substrate, preventing the pigment from precipitating during use. This enables excellent fluidity and uniform dispersion when applied in various composite materials.

[0085] The microencapsulation technology can reduce the negative impact on the environment. The coating layer can isolate the direct contact between the pigment and air and moisture, reducing the release of harmful substances into the environment and contributing to a more environmentally friendly production process.

[0086] The preparation method of the inorganic hydrated salt phase change color developer is as follows:

[0087] It is dissolved at 40°C and slowly crystallized at 5°C, then washed with ethanol and vacuum dried to obtain recrystallized and purified sodium sulfate decahydrate; a composite nucleating agent composed of borax and nano-TiO2 in a ratio of 1:1 is added to inhibit supercooling; subsequently, it is ultrasonically compounded in a molten state at 50°C to form loose particles with a salt absorption rate ≥ 90%; a poly(methyl methacrylate) with a molecular weight of about 50,000 is formulated into a 10 wt% ethyl acetate oil phase solution and 0.5% sorbitan monooleate is added. It is mixed with a 1% sodium dodecyl sulfate aqueous solution containing a 20% solid content phase change complex in a volume ratio of 1:4, emulsified by high-speed shearing at 10000 rpm for 5 minutes to form a stable W / O emulsion, and then the solvent is evaporated by stirring at 40°C for 6 hours. Finally, a microcapsule product with a particle size distribution of 50 - 150 μm and a coating rate exceeding 95% is prepared.

[0088] This color developer utilizes the characteristics of phase change materials and can absorb, store, and release thermal energy within a specific temperature range. By controlling the color change characteristics of the material during phase change, real-time monitoring of temperature changes can be effectively achieved, and it is widely used in building materials, smart clothing, and temperature control systems.

[0089] At the same time, the microencapsulation process makes the combination of the phase change material and the polymer closer, improving the mechanical properties and durability of the material, and also increasing the safety of the phase change material in practical applications. Microcapsules can prevent the leakage of active ingredients and maintain good phase change performance without affecting the environment and users.

[0090] The present invention will be further disclosed below in conjunction with specific examples and comparative examples:

[0091] Example 1

[0092] The materials of the following components are selected in this example:

[0093] a. Geopolymer matrix: including 280 parts of activated fly ash, 70 parts of pickled calcined red mud, 140 parts of calcium silicate magnesium composite activator, 60 parts of modified glass microspheres, and 12 parts of magnesium fluorosilicate crystal nucleus inducer;

[0094] b. Bionic protection system: including 110 parts of gradient-coated diatomite, 55 parts of potassium silicate whiskers derived from straw ash, and 75 parts of micaceous iron oxide;

[0095] c. Color display system: including 85 parts of colored sand, 25 parts of microencapsulated iron oxide pigment, and 8 parts of inorganic hydrated salt phase change color developer;

[0096] d. Functional additives: 20 parts of polycarboxylate dispersant and 15 parts of polyurethane thickener. The viscosity of the polyurethane thickener at 25 °C is 2000 - 3000 cP, and the mass ratio with the polycarboxylate dispersant is 1:1.5.

[0097] The waterproof and weather-resistant exterior wall paint disclosed in the present invention is prepared according to the following steps:

[0098] Step 1. Preparation of geopolymer matrix: Add activated fly ash and red mud to the reaction kettle, premix at 200 rpm for 10 min; add the calcium silicate magnesium activator in 3 batches (with an interval of 15 min), heat up to 60 °C and react for 30 min; add magnesium fluorosilicate and acid-etched glass microspheres, and mix at a low speed of 60 rpm for 30 min;

[0099] Step 2. Composite of bionic protection system: Mix gradient-coated diatomite, potassium silicate whiskers derived from straw ash, and micaceous iron oxide in proportion, ball mill to D50 = 20 - 30 μm, and mix with the matrix obtained in step (1); among them, alumina grinding balls are used for ball milling, the ball-to-material ratio is 5:1, and the ball milling time is 2 - 3 hours.

[0100] Step 3, dispersion of the color development system: Add colored sand, microencapsulated iron oxide pigment, and inorganic hydrated salt phase change color developer into a sand mill, and disperse for 30 minutes at 1500 rpm to form a uniform color paste;

[0101] Step 4, preparation of functional additives: Add polycarboxylate dispersant and polyurethane thickener into the color paste of Step 3, and stir at low speed (200 - 300 rpm) for 10 minutes;

[0102] Step 5, mixing of the finished product: Mechanically stir and mix the materials of Step 2, Step 3, and Step 4 at 1000 rpm for 40 min, then process in a vacuum degassing machine for 20 minutes, and filter and package; the vacuum degree of vacuum degassing is -0.08 to -0.1 MPa, and the solid content of the paint after degassing is ≥65%.

[0103] Example 2

[0104] The difference between this example and Example 1 is only that the dosages of each component are replaced with:

[0105] a. Geopolymer matrix: including 290 parts of activated fly ash, 75 parts of pickled calcined red mud, 145 parts of calcium silicate magnesium composite activator, 65 parts of modified glass microspheres, and 16 parts of magnesium fluorosilicate crystal nucleus inducer;

[0106] b. Bionic protection system: including 115 parts of gradient-coated diatomite, 17 parts of potassium silicate whiskers derived from straw ash, and 78 parts of micaceous iron oxide;

[0107] c. Color development system: including 87 parts of colored sand, 27 parts of microencapsulated iron oxide pigment, and 9 parts of inorganic hydrated salt phase change color developer;

[0108] d. Functional additives: 22 parts of polycarboxylate dispersant and 17 parts of polyurethane thickener.

[0109] Example 3

[0110] The difference between this example and Example 1 is only that the dosages of each component are replaced with:

[0111] a. Geopolymer matrix: including 300 parts of activated fly ash, 80 parts of pickled calcined red mud, 150 parts of calcium silicate magnesium composite activator, 70 parts of modified glass microspheres, and 19 parts of magnesium fluorosilicate crystal nucleus inducer;

[0112] b. Bionic protection system: including 120 parts of gradient-coated diatomite, 60 parts of potassium silicate whiskers derived from straw ash, and 70 parts of micaceous iron oxide;

[0113] c. Color development system: including 90 parts of colored sand, 30 parts of microencapsulated iron oxide pigment, and 10 parts of inorganic hydrated salt phase change color developer;

[0114] d. Functional additives: 25 parts of polycarboxylate dispersant and 20 parts of polyurethane thickener.

[0115] Example 4

[0116] The difference between this example and Example 1 is only that the dosages of each component are replaced with:

[0117] a. Geopolymer matrix: including 310 parts of activated fly ash, 85 parts of pickled calcined red mud, 155 parts of calcium-silicon-magnesium composite activator, 75 parts of modified glass microspheres, and 23 parts of magnesium fluorosilicate crystal nucleus inducer;

[0118] b. Bionic protection system: including 125 parts of gradient-coated diatomite, 63 parts of potassium silicate whiskers derived from straw ash, and 83 parts of mica iron oxide;

[0119] c. Color display system: including 92 parts of colored sand, 32 parts of microencapsulated iron oxide pigment, and 11 parts of inorganic hydrated salt phase change color developer;

[0120] d. Functional additives: 27 parts of polycarboxylate dispersant and 22 parts of polyurethane thickener.

[0121] Example 5

[0122] The difference between this example and Example 1 is only that the dosages of each component are replaced with:

[0123] a. Geopolymer matrix: including 320 parts of activated fly ash, 90 parts of pickled calcined red mud, 160 parts of calcium-silicon-magnesium composite activator, 80 parts of modified glass microspheres, and 25 parts of magnesium fluorosilicate crystal nucleus inducer;

[0124] b. Bionic protection system: including 130 parts of gradient-coated diatomite, 65 parts of potassium silicate whiskers derived from straw ash, and 85 parts of mica iron oxide;

[0125] c. Color display system: including 95 parts of colored sand, 35 parts of microencapsulated iron oxide pigment, and 12 parts of inorganic hydrated salt phase change color developer;

[0126] d. Functional additives: 30 parts of polycarboxylate dispersant and 25 parts of polyurethane thickener.

[0127] Comparative Example 1 (Traditional silicate-based coating)

[0128] Components and preparation:

[0129] a. Matrix material: 300 parts of ordinary Portland cement, 150 parts of quartz sand, and 100 parts of water

[0130] b. Protection system: 100 parts of ordinary diatomite and 50 parts of chopped glass fiber

[0131] c. Color display system: 30 parts of iron oxide red pigment and 20 parts of titanium dioxide

[0132] d. Auxiliary agent: 15 parts of sodium lignosulfonate dispersant

[0133] Preparation steps: Dry-mix cement and quartz sand, then add water and stir into a slurry. Sequentially add the materials of the protection system and mix at low speed, add the color-developing pigment and disperse mechanically, and add the auxiliary agent to adjust the viscosity.

[0134] Comparative Example 2 (lacking the bionic protection system)

[0135] Component adjustment: Geopolymer matrix: the same as in Example 1; Bionic protection system: omit the gradient-coated diatomite, only retain 75 parts of ordinary mica iron oxide; Color-developing system: the same as in Example 1.

[0136] The preparation steps are the same as those in Example 1

[0137] Comparative Example 3 (organic color-developing system)

[0138] Component adjustment: Color-developing system: use 30 parts of conventional organic pigment (phthalocyanine blue) to replace the microencapsulated iron oxide;

[0139] The remaining components and preparation steps are the same as those in Example 1.

[0140] Take the exterior wall paint samples prepared in Examples 1-5 and Comparative Examples 1-3 and conduct the following tests:

[0141] 1. Waterproofness test

[0142] Test method: GB / T1733-1993 "Determination Method for Water Resistance of Paint Films"

[0143] Operation: Immerse the coated specimen in distilled water at (23±2)°C for 96 hours, and calculate the mass water absorption rate. The test results are shown in the following table:

[0144] Test sample Water absorption rate (%) Example 1 2.2 Example 2 2.1 Example 3 1.9 Example 4 2.0 Example 5 2.2 Comparative Example 1 8.6 Comparative Example 2 5.7 Comparative Example 3 5.3

[0145] It can be seen that in terms of waterproofness: the water absorption rates of Examples 1-5 are all lower than 2.5% (the lowest is 1.9%), far better than the national standard (≤6%), indicating that the geopolymer matrix (activated fly ash / red mud) significantly reduces the porosity through a three-dimensional network structure and forms a dense barrier.

[0146] The water absorption rates of Comparative Examples 1-3 are as high as 5.3% - 8.6%. The traditional silicate matrix (Comparative Example 1) has an excessive water absorption rate due to its open pore structure, and the hydrophobic properties of the lack of the bionic protection system (Comparative Example 2) and the organic color-developing system (Comparative Example 3) are poor.

[0147] Conclusion: Through the synergistic effect of the calcium silicate magnesium composite activator and the magnesium fluorosilicate crystal nucleus inducer, the present invention realizes an ultra-low water absorption rate (<2.5%), meeting the stringent waterproof requirements.

[0148] 2. Cold resistance test

[0149] Test method: JG / T 25 - 2017 "Determination of Frost Resistance of Architectural Coating Films"

[0150] Operation: Freeze at -20°C for 4 h → Immerse in water at 23°C for 4 h as one cycle. Observe the cracking situation after 50 cycles. The test results are shown in the following table:

[0151] Test sample Surface condition (after 50 times) Example 1 No visible cracks (rating: Grade I) Example 2 No visible cracks (rating: Grade I) Example 3 No visible cracks (rating: Grade I) Example 4 No visible cracks (rating: Grade I) Example 5 Slight peeling at the edge (rating: Grade II) Comparative Example 1 Overall powdering and peeling (rating: Grade V) Comparative Example 2 Overall powdering and peeling (rating: Grade V) Comparative Example 3 Overall powdering and peeling (rating: Grade V)

[0152] It can be seen from the test results that in terms of low - temperature adaptability: After 50 freeze - thaw cycles at -20°C, there are no cracks in Examples 1 - 4 (rating level I), and only slight peeling at the edges in Example 5 (rating level II). Thanks to the fiber toughening effect of potassium silicate whiskers derived from straw ash (aspect ratio > 20), the low - temperature stress is effectively dispersed.

[0153] In Comparative Examples 1 - 3, all of them are powdered and peeled off (rating level V). Due to the lack of whisker toughening and bionic protection in the traditional system, the brittleness at low temperature is significant.

[0154] Conclusion: The core - shell structure of gradient - coated diatomite and whisker toughening technology in the bionic protection system enable the coating to maintain integrity at extremely low temperatures and are applicable to buildings in alpine regions.

[0155] 3. Heat resistance test

[0156] Test method: GB / T 1735 - 2009 "Determination of Heat Resistance of Paints and Varnishes"

[0157] Operation: Place in an oven at 80°C for 240 h, and measure the change in color difference ΔE and adhesion.

[0158] The test results are shown in the following table:

[0159] Test sample ΔE value Retention rate of adhesion (MPa) (%) Example 1 0.8 98 Example 2 0.7 99 Example 3 0.7 97 Example 4 0.8 97 Example 5 0.9 98 Comparative Example 1 4.3 72 Comparative Example 2 4.6 77 Comparative Example 3 4.1 73

[0160] It can be seen from the test results that in terms of thermal stability: After aging at 80°C for 240 h in Examples 1 - 5, the color difference ΔE is all < 1 (the lowest is 0.7), and the adhesion retention rate ≥ 97%. This indicates that the micro - encapsulated iron oxide pigment (SiO2 coating layer) effectively blocks the thermal oxidation reaction, and the geopolymer matrix has excellent high - temperature resistance.

[0161] In Comparative Examples 1 - 3, the ΔE value > 4, and the adhesion retention rate ≤ 77%. The organic pigment (Comparative Example 3) degrades severely due to heat, and the traditional matrix (Comparative Example 1) has a loose structure at high temperatures.

[0162] Conclusion: The micro - capsule color - showing technology combined with the inorganic matrix significantly improves the color stability and adhesion of the coating in high - temperature environments and is applicable to tropical or sun - exposed areas.

[0163] 4. Crack resistance test

[0164] Test method: ASTM D522 - 1993 "Three - point Bending Test for Crack Resistance of Coatings"

[0165] Operation: Bend the coated plate 180° around a 10 - mm - diameter axis, and observe the crack propagation.

[0166] The test results are as follows:

[0167] Test sample Crack length (mm) Example 1 0.1 Example 2 0.3 Example 3 0 Example 4 0.2 Example 5 0.1 Comparative Example 1 3.4 Comparative Example 2 3.5 Comparative Example 3 4.7

[0168] It can be seen from the test results that in terms of crack resistance: in Examples 1 - 5, the crack length ≤ 0.3 mm in the three - point bending test (no crack in Example 3). The CaCO3 / SiO2 core - shell structure with gradient - coated diatomaceous earth disperses stress through the micro - nano rough surface, improving the toughness of the coating.

[0169] For Comparative Examples 1 - 3, the crack length is 3.4 - 4.7 mm. Due to the lack of a stress - dispersion mechanism in the traditional system, the crack resistance is insufficient.

[0170] Conclusion: The micro - nano structure design of the bionic protection system improves the crack resistance of the coating by more than 5 times, and is applicable to earthquake - prone areas or areas with large temperature differences.

[0171] 5. Stain resistance test

[0172] Test method: GB / T 9780 - 2013 "Test Method for Stain Resistance of Architectural Coating Films"

[0173] Operation: Brush the standard pollution liquid (carbon black / oil mixture), and measure the reflectance loss after rinsing. The test results are shown in the following table:

[0174] Test sample Reflectivity loss (%) Example 1 7.5 Example 2 8.1 Example 3 7.2 Example 4 8.3 Example 5 9.7 Comparative Example 1 32.4 Comparative Example 2 34.5 Comparative Example 3 33.7

[0175] It can be seen from the test results that in terms of stain resistance; in Examples 1 - 5, the reflectance loss ≤ 9.7% (the best is 7.2%). The super - hydrophobic surface (contact angle > 150°) constructed by the bionic protection system makes it difficult for pollutants to adhere, and it can be self - cleaned by rainwater flushing.

[0176] For Comparative Examples 1 - 3, the reflectance loss is as high as 32.4% - 34.5%. The surface roughness of the traditional coating is insufficient, and pollutants are easy to penetrate.

[0177] Conclusion: The coating achieves self - cleaning function through the "lotus - leaf effect", and the stain resistance performance is improved by 80% compared with traditional coatings, significantly reducing the maintenance cost.

[0178] Through the collaborative innovation of geopolymers matrix (dense network structure), bionic protection system (core-shell toughening + whisker reinforcement), and microcapsule color display technology (thermal / light stability), the present invention comprehensively breaks through the technical bottlenecks of traditional exterior wall coatings:

[0179] Waterproof and weather-resistant: water absorption rate ≤ 2.5%, no cracks after 50 freeze-thaw cycles, meeting the protection requirements for extreme climates (severe cold / high temperature). Long-lasting color display: ΔE value < 1, with color stability reaching the leading level in the industry. Green and environmentally friendly: mainly using solid wastes such as fly ash and red mud as raw materials, zero release of VOCs, and reduced carbon emissions. Economical: raw material cost is reduced compared to the silica sol system, and construction efficiency is improved (single-layer coating can meet the standards). It is applicable to areas with high cold, high temperature, high humidity, strong ultraviolet rays, and severe pollution, with cold and heat resistance, crack and frost resistance, waterproof and moisture-proof, acid and alkali resistance, wash and stain resistance. It is developed from natural inorganic mineral raw materials, safe and harmless, pollution-free, and green and environmentally friendly.

[0180] The above shows and describes the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification only illustrates the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. A waterproof and weather-resistant exterior wall paint, characterized in that, Comprising: a. Geopolymer matrix: including 280 - 320 parts of activated fly ash, 70 - 90 parts of pickled calcined red mud, 140 - 160 parts of calcium-silicon-magnesium composite activator, 60 - 80 parts of modified glass microspheres, and 12 - 25 parts of magnesium fluorosilicate crystal nucleus inducer; b. Bionic protection system: including 110 - 130 parts of gradient-coated diatomite, 55 - 65 parts of potassium silicate whiskers derived from straw ash, and 75 - 85 parts of micaceous iron oxide; c. Color display system: including 85 - 95 parts of colored sand, 25 - 35 parts of microencapsulated iron oxide pigment, and 8 - 12 parts of inorganic hydrated salt phase change color developer; d. Functional additives: 20 - 30 parts of polycarboxylate dispersant and 15 - 25 parts of polyurethane thickener.

2. The water-proof and weather-resistant exterior wall paint according to claim 1, characterized in that In the said geopolymer matrix: The specific preparation method of the activated fly ash is as follows: Select fly ash with SiO2 + Al2O3 ≥ 75% from a thermal power plant, activate it by zirconia ball milling. The ball milling parameters are: the diameter of zirconia grinding balls is 10 mm, the ball-to-material ratio is 10:1, and ball mill for 4 h at 45 rpm under nitrogen protection; then carry out atomization treatment with 5% dilute sulfuric acid at a liquid-solid ratio of 0.3:1, age at 60°C for 24 h, wash with water until neutral, and dry to obtain the said activated fly ash; The specific method of pickled calcined red mud is as follows: Dynamically leach the red mud with 10% hydrochloric acid. The dynamic leaching parameters are: solid-liquid ratio 1:5, 200 rpm × 2 h, after pressure filtration, carry out staged calcination (150°C → 350°C → 650°C), and crush to D50 = 15 μm to obtain red-brown fine powder for standby; The specific preparation method of the modified glass microspheres is as follows: Select waste gas glass, wash and crush it into glass microsphere particles with a particle size of 20 - 30 μm, then etch with 40% HF for 30 s and wash with water, then spray-treat with a silane coupling agent KH-550 ethanol solution (2 wt%) to complete surface modification, and then dry at 120°C to obtain the modified glass microspheres. The calcium-silicon-magnesium composite activator is specifically: Sodium silicate with a modulus of 2.1 and a solid content of 40%, slaked lime with Ca(OH)2 ≥ 95%, and magnesium sulfate heptahydrate with MgSO4·7H2O ≥ 99% are sequentially added to a 60°C water bath, control the end point pH = 12.5 ± 0.3, and the viscosity at room temperature ≤ 500 cP to obtain the said calcium-silicon-magnesium composite activator.

3. A waterproof and weather-resistant exterior wall paint according to claim 1, characterized in that, In the said bionic protection system: The specific preparation method of the gradient-coated diatomite is as follows: Select diatomite and mix it with Ca(OH)2 in a volume ratio of 3:1, pass CO2 until pH = 7 to generate a CaCO3 core, then deposit a nano-SiO2 shell layer by the sol-gel method, and after centrifugal separation, dry at 120°C to obtain a core-shell structure powder, which is the gradient-coated diatomite; The method for obtaining potassium silicate whiskers derived from straw ash is as follows: Mix rice straw ash and quartz sand in a volume ratio of 1:2, melt at 1450°C, then cool at a rate of 10°C / min to 800°C and hold for 2 h to grow whiskers, and then carry out ultrasonic treatment with 5% nitric acid for 1 h to obtain potassium silicate whiskers with an aspect ratio > 20.

4. A waterproof and weather-resistant exterior wall paint according to claim 1, characterized in that, In the said color display system: The preparation method of the microencapsulated iron oxide pigment is as follows: The iron oxide red is soaked in 5% dilute hydrochloric acid for 30 minutes at a solid-liquid ratio of 1:

10. Subsequently, tetraethyl orthosilicate, ethanol, and water are mixed in a volume ratio of 1:8:4 to prepare a sol. Meanwhile, under the condition of pH 9 - 10, iron oxide is dispersed in ammonia water / ethanol / water = 5:1:1 to form a suspension; The tetraethyl orthosilicate sol is slowly added dropwise and stirred in a 60°C water bath for 6 hours to uniformly coat the iron oxide particles with SiO2. After centrifugation, ethanol washing, and drying at 60°C, finally, it is calcined at 400°C for 2 hours to obtain a core-shell structure powder; The preparation method of the inorganic hydrated salt phase change color developer is as follows: It is dissolved at 40°C and slowly crystallized at 5°C, then washed with ethanol and vacuum dried to obtain recrystallized and purified sodium sulfate decahydrate; A composite nucleating agent composed of borax and nano-TiO2 in a ratio of 1:1 is added to inhibit supercooling; Subsequently, ultrasonic compounding is carried out in a molten state at 50°C to form loose particles with a salt absorption rate ≥ 90%; Poly(methyl methacrylate) with a molecular weight of about 50,000 is formulated into a 10 wt% ethyl acetate oil phase solution and 0.5% sorbitan monooleate is added. It is mixed with a 1% sodium dodecyl sulfate aqueous solution containing a 20% solid content phase change complex in a volume ratio of 1:4, and emulsified by high-speed shearing at 10,000 rpm for 5 minutes to form a stable W / O emulsion. Then, the solvent is stirred and volatilized at 40°C for 6 hours. Finally, a microcapsule product with a particle size distribution of 50 - 150 μm and a coating rate exceeding 95% is prepared.

5. A waterproof and weather-resistant exterior wall paint according to claim 1, characterized in that, The viscosity of the polyurethane thickener at 25°C is 2000 - 3000 cP, and the mass ratio with the polycarboxylate dispersant is 1:1.

5.

6. A method for preparing the waterproof and weather-resistant exterior wall paint according to any one of claims 1-5, characterized in that, It includes the following steps: Step 1, preparation of the geopolymer matrix: Activated fly ash and red mud are added to a high-speed mixer and premixed at 200 rpm for 10 min first; The calcium silicate magnesium activator is added in 3 batches (with an interval of 15 min), and the temperature is raised to 60°C and reacted for 30 min; Magnesium fluorosilicate and acid-etched glass microspheres are added, and low-speed mixing is carried out at 60 rpm for 30 min; Step 2, compounding of the bionic protection system: Gradient-coated diatomite, potassium silicate whiskers derived from straw ash, and mica iron oxide are mixed in proportion and ball milled to D50 = 20 - 30 μm, and then mixed with the matrix obtained in step (1); Step 3, dispersion of the color development system: Colored sand, microencapsulated iron oxide pigment, and inorganic hydrated salt phase change color developer are added to a sand mill and dispersed at 1500 rpm for 30 minutes to form a uniform color paste; Step 4, preparation of functional additives: The polycarboxylate dispersant and the polyurethane thickener are added to the color paste in step 3 and mixed by low-speed stirring (200 - 300 rpm) for 10 minutes; Step 5, mixing of the finished product: The materials in steps 2, 3, and 4 are mechanically stirred and mixed at 1000 rpm for 40 min, then processed in a vacuum degassing machine for 20 minutes, and filtered and packaged.

7. The preparation method according to claim 6, characterized in that: In step (1), the stirring temperature of the high-speed mixer is 40 - 50°C, and the viscosity of the mixed material ≤ 800 cP.

8. The preparation method according to claim 6, characterized in that: In step (2), the ball milling uses alumina grinding balls, the ball-to-material ratio is 5:1, and the ball milling time is 2 - 3 hours.

9. The preparation method according to claim 6, wherein: In step (5), the vacuum degree for vacuum degassing is -0.08 to -0.1 MPa, and the solid content of the paint after degassing is ≥ 65%.