High-efficiency long-life inorganic dry powder coating with self-humidifying function and preparation method of high-efficiency long-life inorganic dry powder coating

Abstract

The invention relates to an efficient and long-life inorganic dry powder coating with a self-humidifying function and a preparation method thereof, and belongs to the technical field of inorganic coatings. The inorganic dry powder coating comprises the following components in parts by weight: 30-40% of potassium silicate, 10% of expanded perlite, 10-25% of high-activity sepiolite nanofiber, 10% of calcined shell powder, 18-28% of quartz sand and 2-3% of an auxiliary agent. The preparation method comprises the following steps: firstly, treating a sepiolite raw material by virtue of a synergistic process of ultrasonic beam splitting and citric acid activation, so as to obtain high-activity sepiolite nanofibers which are fully dissociated, have nano hierarchical pore channels and are rich in hydrophilic groups; and compounding the high-activity sepiolite nanofiber with calcined shell powder, expanded perlite, quartz sand and potassium silicate to synergistically construct an inorganic coating system with optimized microstructure and efficient moisture absorption / liberation performance. The coating is simple in preparation process and environment-friendly, has excellent mechanical properties and self-humidity-regulating performance, still keeps an efficient humidity-regulating effect in a long-term service environment, and has outstanding long-acting stability.

Description

Technical Field

[0001] This invention relates to the field of inorganic coating technology, specifically to a high-efficiency, long-life self-regulating inorganic dry powder coating and its preparation method, which is a functional inorganic coating suitable for building interior walls. Background Technology

[0002] Indoor humidity not only affects human comfort and health but also significantly impacts the weather resistance and stability of indoor building materials. Therefore, utilizing high-performance self-regulating humidity materials for long-term indoor relative humidity regulation is significant for improving living quality, extending the service life of building materials, and reducing building energy consumption. Currently, self-regulating coating materials can be divided into two categories: organic coatings and inorganic coatings. Organic coatings (such as latex paint) may exhibit problems such as weak moisture release capacity, poor weather resistance, and susceptibility to mold growth under service conditions, directly affecting the service life of building materials. Inorganic coating systems, primarily based on silicate raw materials, possess green and environmentally friendly advantages and are durable and resistant to damage; however, their saturated moisture content is generally low, and their moisture absorption / release capacity is limited, making it difficult to meet the high requirements for self-regulating humidity performance and long-term stability of indoor building materials in different building climate zones. Sepiolite, as a natural mineral material, exhibits a high specific surface area, multi-level nanopores, and abundant surface hydroxyl groups due to its unique nanofiber structure, enabling efficient moisture transport and rapid moisture absorption / release response. This provides a material basis for developing high-performance, long-life inorganic humidity-regulating building materials.

[0003] Patent CN101348629A discloses a humidity-regulating indoor coating and its application method. This invention uses organic emulsions such as acrylic emulsion and styrene-acrylic emulsion as film-forming substances, and porous inorganic mineral materials such as sepiolite, diatomaceous earth, and attapulgite as humidity-regulating materials, and applies them to interior wall coatings. While this coating provides a decorative function, it can effectively regulate indoor air humidity. However, it may face performance degradation during long-term service, leading to a mismatch between its humidity-regulating lifespan and the coating's mechanical durability, thus limiting its long-term application effectiveness. Furthermore, its process and material system are difficult to directly adapt to ordinary civil buildings.

[0004] Therefore, in response to the problems of insufficient moisture absorption / desorption performance and poor stability of existing moisture-regulating coatings, this invention is based on the pore structure and physicochemical properties of natural minerals to obtain highly active sepiolite nanofibers, which are then compounded with other inorganic components to finally propose a low-cost, high-efficiency, and long-life self-regulating inorganic dry powder coating suitable for interior walls of civil buildings. Summary of the Invention

[0005] The purpose of this invention is to provide a high-efficiency, long-life self-regulating inorganic dry powder coating, which has a micro-mesoporous multi-level nanoporous structure and abundant hydrophilic groups, exhibiting high moisture capacity; its stable inorganic components and optimized microstructure ensure long-term moisture regulation stability under service environment.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows: A high-efficiency, long-life self-humidifying inorganic dry powder coating comprises the following components in parts by weight: potassium silicate 30-40%, expanded perlite 10%, highly active sepiolite nanofibers 10-25%, calcined shell powder 10%, quartz sand 18-28%, and additives 2-3%.

[0007] The above-mentioned method for preparing inorganic dry powder coatings first involves treating sepiolite raw materials through a synergistic process of ultrasonic disintegration and citric acid activation to obtain highly active sepiolite nanofibers. Subsequently, these highly active sepiolite nanofibers are compounded with inorganic components such as calcined shell powder, expanded perlite, and quartz sand, with potassium silicate as the main film-forming substance and functional additives added to form an inorganic dry powder coating system.

[0008] The preparation steps of highly active sepiolite nanofibers are as follows: First, the sepiolite raw material is dispersed in deionized water and subjected to ultrasonic treatment; then, the treated sepiolite fibers are placed in a citric acid solution for stirring and activation treatment; finally, the product is washed with water, filtered, dried and sieved to obtain the highly active sepiolite nanofibers.

[0009] Specifically, the purity of sepiolite raw materials is above 30%, and they pass through a 100-mesh sieve.

[0010] Preferably, during the ultrasonic unbundling process, the mass ratio of sepiolite raw material to deionized water is 1:50, the ultrasonic power is 400-1000 W, the working interval is 4s:4s, and the treatment time is 2-4 hours. More preferably, the ultrasonic power is 500-700 W, the ultrasonic working interval is 4s:4s, and the treatment time is 2-3 hours. Preferably, the ultrasonic power is 500W, 550W, 600W, 650W, or 700W, and the ultrasonic time is 2 hours.

[0011] Specifically, during the citric acid activation treatment, the mass ratio of sepiolite fiber to citric acid solution was 1:50, the citric acid concentration was 0.5 mol / L, the stirring rate was 1200-1500 r / min, and the treatment time was 12-15 h.

[0012] Specifically, after ultrasonic disintegration and citric acid activation treatment, the product is repeatedly washed with deionized water until neutral, filtered through an 80-120 μm filter membrane, the filter cake is dried at 80℃ to constant weight, and then passed through a 200-mesh sieve.

[0013] Specifically, the modulus of potassium silicate is 2.6-2.8, the particle size of expanded perlite is 800-1000 mesh, the particle size of quartz sand is 200-400 mesh, and the particle size of calcined shell powder is 200-400 mesh.

[0014] Preferably, the additives include 0.4-0.5% dispersant, 0.5-0.7% thickener, 0.6-0.8% curing agent and 0.5-1% cellulose.

[0015] Preferably, the dispersant is one of polyethylene glycol, sodium hexametaphosphate, and sodium disilicate.

[0016] Preferably, the thickener is one of sodium polyacrylate, aluminum silicate, and silica.

[0017] Preferably, the curing agent is one of sodium fluorosilicate, potassium fluorosilicate, and magnesium fluorosilicate.

[0018] Preferably, the cellulose is one of hydroxypropyl methylcellulose, hydroxyethyl cellulose, and carboxymethyl cellulose.

[0019] This invention also protects the application of the aforementioned inorganic dry powder coating, which is prepared into a film and used as an interior wall coating for building construction.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) This invention uses highly active sepiolite nanofibers as the moisture-regulating functional unit, endowing the coating with efficient and long-lasting ability to regulate indoor humidity. Through a synergistic process of ultrasonic debinding and citric acid activation of sepiolite raw materials, highly active sepiolite nanofibers with high moisture content and rapid moisture absorption / desorption response are obtained. First, the extreme local pressure and microjets generated by the ultrasonic cavitation effect exert significant shear force on the sepiolite fiber bundles, effectively breaking the van der Waals forces and hydrogen bonds between the fibers, dissociating the aggregated fiber bundles into single nanofibers with a diameter of 30-60 nm, significantly increasing the specific surface area of ​​the material and fully exposing its internal pores. Subsequently, in the citric acid activation stage, the carboxyl groups and impurity ions (such as Mg) in the sepiolite fibers... 2+ Ca 2 + A chelation reaction occurs, dissolving and removing blockages such as carbonates, effectively unclogging the nanopores of the mineral fibers. Simultaneously, the carboxylic acid groups of the citric acid molecules coordinate with the magnesium-oxygen octahedra on the surface and edges of the sepiolite fibers, achieving surface grafting of strongly hydrophilic groups. These highly active sepiolite nanofibers possess excellent pore structure and abundant surface hydrophilic groups, enabling efficient moisture transport and rapid moisture absorption / desorption responses, providing a crucial guarantee for the high-efficiency moisture regulation performance of coatings.

[0021] (2) This invention utilizes the synergistic effect of mineral components such as highly active sepiolite nanofibers, expanded perlite, calcined shell powder and quartz sand to construct an inorganic coating system with both excellent mechanical properties and moisture-regulating properties. Potassium silicate is used as the film-forming material, forming a three-dimensional siloxane film-forming network through hydrolysis and condensation to constitute the coating skeleton. Quartz sand serves as a rigid skeleton, filling the potassium silicate cementing system and providing basic mechanical strength and wear resistance for the coating. Fully dissociated highly active sepiolite nanofibers are uniformly interspersed within the three-dimensional siloxane film-forming network, optimizing the system's toughness and alleviating the problem of easy cracking of the coating. Calcined shell powder regulates the alkalinity of the system through hydration reaction, which can accelerate the curing process of potassium silicate. In addition, the unique layered porous structure of expanded perlite complements the fine micropores of calcined shell powder, and together with the multi-level nanopores of sepiolite nanofibers, they form an efficient moisture adsorption-storage-transport network, thereby efficiently adsorbing and storing water vapor in the air, providing the coating with high moisture content and stability in multiple moisture absorption and desorption cycles. The synergistic effect of multiple components ultimately achieves a balance between the mechanical durability and long-term moisture regulation stability of the coating. Attached Figure Description

[0022] Figure 1 This is a scanning electron microscope image of highly active sepiolite nanofibers. Figure 2 The nitrogen adsorption-desorption isotherm and pore size distribution diagram of the coating film prepared in Example 1 are shown. Figure 3 The moisture absorption / desorption curves are for the coatings prepared in Examples 1-5 and Comparative Examples 1-3. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments. The described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0024] Example 1: The inorganic dry powder coating of this embodiment includes the following components by weight: 40% potassium silicate with a modulus of 2.6, 10% 800-mesh expanded perlite, 20% highly active sepiolite nanofibers, 10% 200-mesh calcined seashell powder, 18% 200-mesh quartz sand, and 2% additives.

[0025] The 2% additives include: 0.4% polyethylene glycol, 0.5% sodium polyacrylate, 0.6% sodium fluorosilicate, and 0.5% hydroxypropyl methylcellulose.

[0026] The preparation steps of highly active sepiolite nanofibers are as follows: First, 30% pure sepiolite raw material is passed through a 100-mesh sieve. The sepiolite raw material is dispersed in deionized water at a mass ratio of 1:50. The material is then ultrasonically treated for 2 hours under the conditions of ultrasonic power of 500 W and working interval of 4s:4s to obtain the treated sepiolite fibers. The treated sepiolite fibers were placed in a 0.5 mol / L citric acid solution with a mass ratio of sepiolite fibers to citric acid solution of 1:50. After stirring at 1500 r / min for 12 h, the solution was repeatedly washed with deionized water until neutral. The solution was then filtered through an 80-120 μm filter membrane. The filter cake was dried at 80 °C to constant weight and passed through a 200-mesh sieve to obtain highly active sepiolite nanofibers.

[0027] Example 2: The formulation of the inorganic dry powder coating and the preparation process of the highly active sepiolite nanofibers in this embodiment are the same as in Example 1, except that the ultrasonic power is set to 1000 W in the preparation process of the highly active sepiolite nanofibers.

[0028] Example 3: The formulation of the inorganic dry powder coating and the preparation process of the highly active sepiolite nanofibers in this embodiment are the same as in Example 1. The difference is that the ultrasonic treatment is carried out for 4 hours with an ultrasonic power of 500 W and a working interval of 4s:4s during the preparation of the highly active sepiolite nanofibers.

[0029] Example 4: This embodiment describes an inorganic dry powder coating comprising the following components by weight: 40% potassium silicate with a modulus of 2.6, 10% 800-mesh expanded perlite, 10% highly active sepiolite nanofibers, 10% 200-mesh calcined seashell powder, 28% 200-mesh quartz sand, and 2% additives.

[0030] The 2% additives are the same as in Example 1, and the preparation of highly active sepiolite nanofibers is the same as in Example 1.

[0031] Example 5: This embodiment describes an inorganic dry powder coating comprising the following components by weight: 30% potassium silicate with a modulus of 2.6, 10% 800-mesh expanded perlite, 20% highly active sepiolite nanofibers, 10% 200-mesh calcined seashell powder, 28% 200-mesh quartz sand, and 2% additives.

[0032] The 2% additives are the same as in Example 1, and the preparation of highly active sepiolite nanofibers is the same as in Example 1.

[0033] Comparative Example 1: The formulation of this comparative example inorganic dry powder coating is the same as that of Example 1, except that acid-treated sepiolite is used instead of highly active sepiolite nanofibers in this comparative example. It includes the following components by weight fraction: 40% potassium silicate with a modulus of 2.6, 10% 800-mesh expanded perlite, 20% acid-treated sepiolite, 10% 200-mesh calcined seashell powder, 18% 200-mesh quartz sand, and 2% additives.

[0034] The preparation steps of acid-treated sepiolite are as follows: 30% pure sepiolite raw material is passed through a 100-mesh sieve. The sepiolite is placed in a 0.5 mol / L citric acid solution at a mass ratio of 1:50 (sepiolite mass to citric acid solution mass). The mixture is stirred at 1500 r / min for 12 h, then repeatedly washed with deionized water until neutral. The mixture is filtered through an 80-120 μm filter membrane. The filter cake is dried at 80℃ to constant weight and passed through a 200-mesh sieve to obtain acid-treated sepiolite.

[0035] Comparative Example 2: The formulation of this comparative example inorganic dry powder coating is the same as that of Example 1, except that expanded perlite is not added in this comparative example. It includes the following components by weight fraction: 40% potassium silicate with a modulus of 2.6, 20% highly active sepiolite nanofibers, 10% 200-mesh calcined seashell powder, 28% 200-mesh quartz sand, and 2% additives.

[0036] Comparative Example 3: The formulation of this comparative example inorganic dry powder coating is the same as that of Example 1, except that calcined seashell powder is not added in this comparative example. It includes the following components by weight: 40% potassium silicate with a modulus of 2.6, 10% 800-mesh expanded perlite, 20% highly active sepiolite nanofibers, 28% 200-mesh quartz sand, and 2% additives.

[0037] To further illustrate the performance of the self-humidifying inorganic dry powder coating provided by the present invention, the inorganic dry powder coatings of Examples 1-5 and Comparative Examples 1-3 were prepared into coating films. The specific steps are as follows: the inorganic dry powder coating was added to water at a ratio of 20:11 (coating mass to water mass) and stirred at high speed until there were no particles, to obtain a coating slurry. The coating slurry was then applied to a gypsum board by roller coating, with a thickness of 1-3 mm, and cured at room temperature for 21 days to obtain a coating film.

[0038] According to standard JG / T 445-2014 "Inorganic Dry Powder Architectural Coatings", the coatings prepared in Examples 1-5 were tested for technical performance. The coatings showed uniform dispersion, smooth roller application within 2 hours, normal appearance, surface drying time ≤ 2 hours, white contrast ratio ≥ 0.95, good flexibility without cracks, no abnormalities in 48-hour alkali resistance test, brushing resistance > 2000 cycles, volatile organic compound content < 1 g / kg, total benzene content < 50 mg / kg, and free formaldehyde content < 5 mg / kg. All met the technical requirements for the best grade I inorganic dry powder interior wall coatings.

[0039] The mildew resistance levels of the coatings prepared in Examples 1-5 were determined according to standard GB / T 1741-2020 "Test Method for Mildew Resistance of Coatings". All coatings met the level 0 mildew resistance standard. This indicates that the prepared coatings have good mildew resistance and will not produce mildew during the conditioning process.

[0040] The moisture absorption / release properties of the coatings prepared in Examples 1-5 and Comparative Examples 1-3 were tested. The specific steps were as follows: The cured coating film was dried at 80 °C for 5 h, and then placed in a constant temperature and humidity chamber at 23 °C and 95% relative humidity. The mass change of the coating film was recorded within 12 h. Then, the environmental conditions inside the constant temperature and humidity chamber were changed to 23 °C and 70% relative humidity, and the mass change of the coating film was recorded within 12 h. The mass change of the coating film in the container was recorded using a weight sensor, and the moisture absorption and release of the material were calculated from the mass change.

[0041] As shown in Table 1, the coatings prepared in Examples 1-5 exhibit excellent moisture absorption and release capabilities, far exceeding those of the coating prepared in Comparative Example 1, which only used acid-treated sepiolite raw materials. This indicates that highly active sepiolite nanofibers can impart excellent pore structure and efficient moisture absorption / release properties to the coatings, while unbundled acid-treated sepiolite cannot provide the coatings with efficient moisture absorption and release capabilities. (See attached table.) Figure 1 As shown, the sepiolite fibers treated with ultrasound and citric acid exhibit a highly independent dispersion state, with the fiber bundles fully dissociated into single nanofibers with diameters of 30-60 nm and fiber lengths of 3-5 μm.

[0042] The nitrogen adsorption-desorption isotherm and pore size distribution diagram of the coating film prepared in Example 1 are attached. Figure 2 As shown, the coating exhibits a rich nano-level porous structure, with pore sizes primarily distributed in the 1-10 nm range. BET analysis indicates that the coating has a specific surface area as high as 57.8 m². 2 / g, average pore size is 5.56 nm, and total pore volume is 0.08 cm³. 3 / g, this micro-mesoporous composite multi-level nanoporous structure provides a large number of adsorption sites and fast transport channels for water molecules, enabling high moisture content and rapid moisture absorption / desorption response.

[0043] Table 1. Self-regulating moisture properties of coatings prepared in the examples and comparative examples.

[0044] The coating film prepared in Example 1 exhibited the highest moisture absorption / release performance, with a moisture absorption of 55.18 wt% and a moisture release of 36.11 wt%. The moisture absorption and release of the coating films prepared in Examples 2 and 3 were lower than those in Example 1, indicating that different ultrasonic power and duration affect the unbundling effect of sepiolite fibers, thus influencing their dispersion in the coating film. Testing revealed that an ultrasonic power of 500-700W and an ultrasonic time of 2-3 hours were optimal, under which both moisture absorption and release remained at a good level, with minimal attenuation during lifetime testing. The moisture absorption and release data of the coating film prepared in Example 4 showed that highly active sepiolite nanofibers are the main self-regulating moisture functional unit, and their addition amount significantly affects the overall moisture regulation capability of the coating film. The optimal addition amount of highly active sepiolite nanofibers was 15%~25%. The moisture absorption / desorption properties of the coatings prepared in Example 5 and Example 1 are quite similar, indicating that the amount of potassium silicate mainly affects the mechanical properties of the coating and has little impact on the moisture conditioning properties.

[0045] The comparison of the moisture absorption and release of the coatings prepared in Example 1, Comparative Example 2 and Comparative Example 3 shows that the presence of calcined shell powder and expanded perlite has a key influence on the self-humidification performance of the coating. The two complement each other to construct a nanoporous structure, and together with highly active sepiolite nanofibers, they synergistically construct an efficient three-dimensional network structure for water vapor adsorption and storage, which significantly improves the humidity regulation performance.

[0046] Table 2. Moisture absorption / desorption properties of the coatings prepared in the Examples and Comparative Examples after the 40th cycle.

[0047] To more comprehensively evaluate the moisture-regulating capacity of the coating, a periodic moisture absorption / desorption cycle test was conducted. Referring to GB / T 35166-2017 "Determination of Moisture Absorption / Desorption Properties of Building Materials and Products - Humidity Reaction Method", forty cycles of testing were performed on the coating prepared in Example 1. After the fortieth cycle, the moisture absorption of the coating prepared in Example 1 was 54.74 wt%, a decrease of 0.80% compared to the first cycle, and the moisture release was 35.59 wt%, a decrease of 1.44% compared to the first cycle, maintaining high-efficiency moisture absorption / desorption performance and exhibiting good cycle stability. The coating prepared in Comparative Example 2 showed slight blistering, with a moisture absorption of 25.37 wt%, a decrease of 20.99% compared to the first cycle, and a moisture release of 15.41 wt%, a decrease of 18.89% compared to the first cycle, indicating that expanded perlite is more important for the cycle stability of the coating. The moisture absorption of the coating film prepared in Comparative Example 3 was 29.87 wt%, a decrease of 6.63% in performance compared to the first cycle, and the moisture release was 21.76 wt%, a decrease of 8.84% in performance compared to the first cycle. This indicates that the lack of calcined seashell powder will lead to a decrease in the moisture absorption / release performance of the coating film during cycles.

[0048] Table 3. Moisture absorption / desorption properties of the coatings prepared in the examples and comparative examples after brushing.

[0049] To further evaluate the moisture-regulating life of the coating, the coatings prepared in the examples and comparative examples were subjected to 10,000 brushing cycles according to GB / T 9266-2009 "Determination of Brush Resistance of Architectural Coatings", and the self-regulating moisture properties of the coatings were tested. As shown in Table 3, after 10,000 brushing cycles, the surface of the coating prepared in Example 1 showed no blistering, discoloration, or cracking. Its moisture absorption was 51.66 wt%, a performance decrease of 6.38% compared to before brushing, and its moisture release was 32.07 wt%, a performance decrease of 11.19% compared to before brushing. This indicates that the inorganic dry powder coating has a highly efficient and long-lasting self-regulating moisture function, and can maintain a highly efficient moisture-regulating ability for 15-20 years. Comparative Example 2 showed a good coating surface with a moisture absorption of 26.77 wt%, a performance decrease of 16.63% compared to before washing, and a moisture release of 16.58%, a performance decrease of 12.74% compared to before washing. This indicates that the lack of expanded perlite leads to incomplete moisture-regulating network construction. In contrast, Comparative Example 3 showed several small cracks on its coating surface. Its moisture absorption was 25.91 wt%, a performance decrease of 19.00% compared to before washing, and its moisture release was 19.22 wt%, a performance decrease of 19.48% compared to before washing. This indicates that the lack of calcined seashell powder resulted in lower potassium silicate curing degree and poorer washability and moisture-regulating properties.

[0050] Any aspects not covered in this invention are applicable to existing technologies.

Claims

1. A high-efficiency, long-life self-regulating moisture-regulating inorganic dry powder coating, characterized in that, The composition includes the following components by weight: potassium silicate 30-40%, expanded perlite 10%, highly active sepiolite nanofibers 10-25%, calcined shell powder 10%, quartz sand 18-28%, and additives 2-3%; The highly active sepiolite nanofibers are obtained by treating sepiolite raw materials through a synergistic process of ultrasonic disintegration and citric acid activation. The specific process is as follows: First, the sepiolite raw materials are dispersed in deionized water and subjected to ultrasonic treatment; then, the treated sepiolite fibers are placed in a citric acid solution for stirring and activation treatment; finally, the product is washed, filtered, dried, and sieved to obtain the highly active sepiolite nanofibers.

2. The functional inorganic dry powder coating according to claim 1, characterized in that, The inorganic dry powder coating comprises the following components by weight: 30-40% potassium silicate, 10% expanded perlite, 15-20% highly active sepiolite nanofibers, 10% calcined shell powder, 23-28% quartz sand, and 2-3% additives.

3. The functional inorganic dry powder coating according to claim 1, characterized in that, The purity of the sepiolite raw material is above 30%, and it passes through a 100-mesh sieve. During the ultrasonic dissociation treatment, the mass ratio of sepiolite raw material to deionized water is 1:50, the ultrasonic power is 400-1000 W, the working interval is 4s:4s, and the treatment time is 2-4 hours. During the citric acid activation treatment, the mass ratio of sepiolite fiber to citric acid solution was 1:50, the citric acid concentration was 0.5 mol / L, the stirring rate was 1200-1500 r / min, and the treatment time was 12-15 h.

4. The functional inorganic dry powder coating according to claim 1, characterized in that, The ultrasonic power is 500-700 W, the ultrasonic working interval is 4s:4s, and the processing time is 2-3 hours.

5. The functional inorganic dry powder coating according to claim 1, characterized in that, After ultrasonic dissociation and citric acid activation treatment, the product is repeatedly washed with deionized water until neutral, filtered through an 80-120 μm filter membrane, dried at 80℃ to constant weight, and passed through a 200-mesh sieve.

6. The inorganic dry powder coating according to claim 1, characterized in that, The potassium silicate has a modulus of 2.6-2.8, the expanded perlite has a particle size of 800-1000 mesh, the quartz sand has a particle size of 200-400 mesh, and the calcined shell powder has a particle size of 200-400 mesh.

7. The inorganic dry powder coating according to claim 1, characterized in that, The additives include 0.4-0.5% dispersant, 0.5-0.7% thickener, 0.6-0.8% curing agent, and 0.5-1% cellulose; The dispersant is one of polyethylene glycol, sodium hexametaphosphate, and sodium disilicate; The thickener is one of sodium polyacrylate, aluminum silicate, and silica. The curing agent is one of sodium fluorosilicate, potassium fluorosilicate, and magnesium fluorosilicate; The cellulose is one of hydroxypropyl methylcellulose, hydroxyethyl cellulose, and carboxymethyl cellulose.

8. A method for preparing a high-efficiency, long-life self-regulating moisture-regulating inorganic dry powder coating as described in any one of claims 1-7, characterized in that, The preparation method includes the following steps: First, the sepiolite raw material is treated by a synergistic process of ultrasonic disintegration and citric acid activation to obtain highly active sepiolite nanofibers; then, the highly active sepiolite nanofibers are compounded with inorganic components such as calcined shell powder, expanded perlite and quartz sand, with potassium silicate as the main film-forming substance and functional additives added to form an inorganic dry powder coating system.

9. The application of the inorganic dry powder coating according to claim 1, characterized in that, The coating is prepared into a film and used as an interior wall coating for buildings.

10. The application according to claim 8, characterized in that, The inorganic dry powder coating is added to water at a ratio of 20:11 (coating mass to water mass) and stirred at high speed until there are no particles, resulting in a coating slurry. The coating slurry is then applied to gypsum board by roller coating, maintaining a thickness of 1-3 mm, and cured at room temperature for 21 days to obtain a coating film. The moisture content of the coating film is above 50 wt%, the moisture release is above 25 wt%, and in the periodic moisture absorption / release cycle test, the moisture absorption / release attenuation is controlled within 5%, preferably within 2%. After 10,000 cycles of scrubbing resistance test, the coating film surface shows no blistering, discoloration, or cracking, and the moisture absorption attenuation is controlled within 10%, and the moisture release attenuation is controlled within 12%.

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