Water-resistant putty powder for interior walls and preparation method thereof

Abstract

The present application relates to the technical field of building materials, and specifically discloses a water-resistant putty powder for interior walls and a preparation method thereof. A water-resistant putty powder for interior walls, the raw materials of which include: sulphoaluminate cement, nano-heavy calcium powder, silica fume, double MOF composite nanotubes, modified diatomaceous earth, polypropylene fiber, nano-titanium dioxide, defoaming agent, dispersant and mildew inhibitor. The double MOF composite nanotubes are obtained by loading copper trimesic acid in the inner cavity of halloysite nanotubes and loading dimethylimidazole cobalt on the outer wall; the modified diatomaceous earth is obtained by modifying diatomaceous earth with stearic acid. The water-resistant putty powder for interior walls of the present application uses double MOF composite nanotubes as the core functional material, and under the synergistic effect of multiple components, it effectively enhances the water resistance and air permeability of the putty layer.

Description

Technical Field

[0001] The present application belongs to the technical field of building materials, and more specifically, relates to a water-resistant putty powder for interior walls and a preparation method thereof. Background Art

[0002] In the field of architectural decoration, putty powder is a crucial material for wall base treatment. Its primary function is to fill the wall surface and provide a smooth base for subsequent coatings or decorative layers. Water-resistant interior wall putty powder, a special type of putty powder, is commonly used in humid environments such as kitchens, bathrooms, and basements, as well as on interior walls in high-humidity regions of the south. This putty powder, through a special formula design, boasts enhanced water resistance compared to conventional putty powder. It effectively prevents problems such as powdering, shedding, and mold in the putty layer caused by moisture intrusion, providing better protection for the wall and extending the life of the wall decoration.

[0003] In the prior art, many interior wall water-resistant putty powders improve water resistance by increasing the content of cement, redispersible latex powder and other gelling materials, or adding silicone hydrophobic agents, etc., to form a dense waterproof film. For example, the patent application document with publication number CN103881456A discloses a latex exterior wall water-resistant putty powder, the raw materials of which include white cement, heavy calcium carbonate, polymer latex powder, kaolin and cellulose ether. By increasing the amount of cement and using specific polymer latex powder, a continuous waterproof structure is formed on the surface of the putty layer, thereby improving the water resistance of the putty. This technical solution of enhancing water resistance by constructing a dense waterproof layer solves the problem of putty being damaged by water to a certain extent and meets the use requirements in some humid environments.

[0004] However, the above-mentioned prior art generally has the defect of poor air permeability when improving water resistance. Since the formation of a dense adhesive film closes the pores of the putty layer, the water vapor inside the wall cannot be effectively discharged. In the rainy season in the south, in a long-term humid indoor environment, or when there is condensed water inside the wall, water vapor is trapped inside the wall, which can easily cause problems such as moisture and mold in the base layer and hollowing and falling off of the putty layer. In addition, insufficient air permeability may also affect the heat and moisture exchange of the wall, resulting in an imbalance in indoor humidity regulation, and even forming condensed water between the putty layer and the paint layer, affecting the decorative effect and service life of the paint. Therefore, how to effectively improve the air permeability of the putty powder while ensuring its water resistance has become a technical problem that needs to be solved urgently. To solve this problem, the present application provides a water-resistant putty powder for interior walls and a preparation method thereof, which achieves a synergistic improvement in water resistance and air permeability through innovative formula design and preparation process. Summary of the Invention

[0005] In order to ensure that the putty layer has good water resistance while enhancing its air permeability, the present application provides an interior wall water-resistant putty powder and a preparation method thereof.

[0006] The present application provides a water-resistant putty powder for interior walls that adopts the following technical solution:

[0007] A water-resistant putty powder for interior walls is prepared from the following raw materials in parts by weight:

[0008] 18-22 parts of sulphoaluminate cement;

[0009] 35-45 parts of nano calcium powder;

[0010] 12-18 parts of silica fume;

[0011] 3-6 parts of dual-MOF composite nanotubes;

[0012] 8-12 parts of modified diatomaceous earth;

[0013] Polypropylene fiber 0.2-0.4 parts;

[0014] 0.5-1 part of nano titanium dioxide;

[0015] 0.5-1 part of defoaming agent;

[0016] Dispersant 0.5-1 part;

[0017] 0.5-1 part of mildew inhibitor;

[0018] The dual-MOF composite nanotube is obtained by loading copper trimesate in the inner cavity of the halloysite nanotube and loading cobalt dimethylimidazole on the outer wall;

[0019] The modified diatomaceous earth is obtained by modifying diatomaceous earth with stearic acid.

[0020] By adopting the above technical solution, sulfoaluminate cement and silica fume serve as the primary binders, which hydrate to form ettringite and a low-calcium ratio CSH gel, forming a rigid skeleton that enhances early strength and water resistance, fills cement pores, increases density, and acts as a water barrier. Nano-titanium dioxide enhances surface hydrophilicity in response to ultraviolet light, facilitating water vapor diffusion. By introducing dual MOF composite nanotubes, the tubular structure of the halloysite nanotubes provides a directional channel for water vapor transmission, overcoming the poor breathability of the dense layer of traditional putty. The microporous structure of copper trimesicate loaded within the halloysite nanotubes selectively adsorbs water vapor molecules, thus overcoming the mold-prone wall putty in high-humidity environments. The cobalt dimethylimidazolium loaded on the outer wall of the halloysite nanotubes exhibits excellent hydrophobicity. Its uniform pores selectively allow small water vapor molecules to pass through, while blocking large liquid water clusters. This effectively improves the water resistance and breathability of the wall putty. By modifying diatomaceous earth, the stearic acid hydrophobic chains cover the hydroxyl groups on the surface of the diatomaceous earth, reducing the surface energy and reducing the adsorption of liquid water. At the same time, the natural porous structure of the diatomaceous earth and the dual MOF composite nanotube pores can be retained as much as possible to form a through transmission network, thereby effectively enhancing the air permeability of the putty layer.

[0021] Optionally, the dual-MOF composite nanotubes are prepared by the following method:

[0022] A. Immerse the halloysite nanotube powder in an ethanol solution of a silane coupling agent, reflux and stir at 70-80° C. for 3-5 hours, filter, wash with ethanol, and dry to obtain activated halloysite nanotubes;

[0023] B. Dispersing the activated halloysite nanotubes in a copper-based precursor solution, ultrasonically treating for 1-3 hours, then transferring to a hydrothermal reactor, reacting at 110-120° C. for 10-12 hours, then washing with ethanol and drying to obtain the halloysite nanotubes with copper trimesic acid loaded in the inner cavity;

[0024] C. Halloysite nanotubes with copper trimesic acid loaded in the inner cavity are dispersed in a cobalt-based precursor solution, stirred and reacted at room temperature for 20-24 hours, and then centrifuged. The solid product is washed and dried to obtain dual-MOF composite nanotubes.

[0025] By employing this technical solution, amino groups are introduced onto the surface of halloysite nanotubes via a silane coupling agent, enhancing coordination with MOF. This ensures the secure loading of copper trimesate and cobalt dimethylimidazolium onto the halloysite nanotube surface, further enhancing the structural stability of the dual-MOF composite nanotubes. The synergistic effect of copper trimesate loading on the inner wall and cobalt dimethylimidazolium on the outer wall enhances the water resistance and air permeability of the putty layer.

[0026] Optionally, the copper-based precursor solution is prepared by dissolving copper nitrate and trimesic acid in N,N-dimethylformamide, and ultrasonically mixing the mixture to obtain the copper-based precursor solution.

[0027] Optionally, the mass ratio of the copper nitrate, trimesic acid and N,N-dimethylformamide is 1:(1.2-1.5):(8-10).

[0028] By adopting the above technical solution, the above ratio of copper nitrate and trimesic acid can ensure that Cu 2+ The DMF solvent is conducive to maintaining the homogeneity of the system, and the high boiling point of DMF can avoid the solvent from evaporating too quickly during the hydrothermal reaction, thereby ensuring the complete growth of MOF crystals.

[0029] Optionally, the cobalt-based precursor solution is prepared by dissolving cobalt nitrate hexahydrate and 2-methylimidazole in methanol, and stirring until the cobalt-based precursor solution is completely dissolved.

[0030] Optionally, the mass ratio of the cobalt nitrate hexahydrate, 2-methylimidazole and methanol is 1:(3-4):(20-25).

[0031] By adopting the above technical solution, 2-methylimidazole is excessive to form an alkaline environment, which accelerates the 2+ Self-assembly with imidazole ligands; the polarity of methanol matches the growth requirements of ZIF-67, avoiding the solvation effect that inhibits crystal formation, which is conducive to the formation of dual-MOF composite nanotubes with stable structural properties.

[0032] Optionally, the mass ratio of the halloysite nanotube powder to the ethanol solution of the silane coupling agent is 1:(8-10), and the mass concentration of the ethanol solution of the silane coupling agent is 3%-5%.

[0033] By adopting the above technical solution, the silane coupling agent in the above concentration range can form a monomolecular layer on the halloysite surface, and the directional arrangement of the amino groups provides anchoring points for subsequent MOF loading, which is beneficial to improving the interface bonding strength between the metal organic framework crystal and the halloysite nanotubes.

[0034] Optionally, the modified diatomaceous earth is prepared by the following method:

[0035] Diatomaceous earth and stearic acid are mixed in a mass ratio of (10-15):1, stirred and reacted at 70-80°C for 2-3h, and ball-milled after cooling to obtain modified diatomaceous earth.

[0036] Optionally, the polypropylene fiber has a diameter of 15-20 μm and a length of 3-5 mm.

[0037] By adopting the above technical solution, fibers with too fine diameters are prone to agglomeration, while fibers with too thick diameters will destroy the surface smoothness; polypropylene fibers of the above size can effectively bridge microcracks, thereby enhancing the anti-cracking performance of putty powder.

[0038] The present application also provides a method for preparing water-resistant putty powder for interior walls, which adopts the following technical solution:

[0039] A method for preparing water-resistant putty powder for interior walls comprises the following steps:

[0040] S1. Add sulphoaluminate cement, nano-heavy calcium powder, silica fume, modified diatomaceous earth, double MOF composite nanotubes, nano-titanium dioxide, and mildew inhibitor into a dry powder mixer and stir at 200-300 rpm for 10-15 minutes to obtain a premix;

[0041] S2. Mix the polypropylene fiber with the premix, add a defoamer and a dispersant, stir at 800-1000 rpm for 5-8 minutes, and then pack into moisture-proof packaging bags to obtain interior wall water-resistant putty powder.

[0042] Using this approach, dry material premixing (200-300 rpm) prevents direct high-speed collisions between the MOF and fibers, which could lead to structural damage. High-speed dispersion of the fibers and additives (800-1000 rpm) ensures agglomeration, improving crack resistance while preventing agglomerates from clogging the ventilation pores. Moisture-proof packaging prevents failure of the dual-MOF composite tubes and ensures stable performance during storage.

[0043] In summary, this application has the following beneficial effects:

[0044] 1. Since this application uses dual MOF composite nanotubes as the core functional material, the inner cavity of the halloysite nanotube is loaded with copper trimesic acid and the outer wall is loaded with dimethylimidazole cobalt, and the microporous structure of copper trimesic acid is used to selectively adsorb water vapor molecules and play the role of Cu 2+ The antibacterial properties of the compound overcome mold in high-humidity environments. The hydrophobicity and uniform pores of cobalt dimethylimidazole allow the passage of small water vapor molecules while blocking large liquid water clusters. The tubular structure of halloysite nanotubes provides a directional channel for water vapor transmission. The synergistic effect of these multiple components effectively enhances the water resistance and air permeability of the putty layer.

[0045] 2. In this application, stearic acid is preferably used to modify diatomaceous earth. The hydroxyl groups on the surface of diatomaceous earth are covered by the hydrophobic chains of stearic acid to reduce the surface energy and reduce the adsorption of liquid water. At the same time, the natural porous structure of diatomaceous earth is retained, so that it forms a through transmission network with the pores of the dual MOF composite nanotubes. Therefore, it can help enhance the air permeability of the putty layer, reduce costs, and synergistically improve the overall water resistance and air permeability.

[0046] 3. The method of this application uses polypropylene fibers with a diameter of 15-20 μm and a length of 3-5 mm to effectively bridge microcracks, enhance the putty powder's crack resistance, and prevent water seepage caused by cracks. Simultaneously, it is combined with additives such as defoamers, dispersants, and mildew inhibitors. The defoamer reduces the formation of large bubbles, thereby preventing the formation of water seepage channels; the dispersant ensures the uniform dispersion of the nanomaterials; and the mildew inhibitor inhibits the growth of mold. This effectively improves the putty powder's construction performance, structural stability, and durability, ensuring the long-term use of the putty in humid environments. DETAILED DESCRIPTION

[0047] The present application is further described in detail below with reference to the embodiments.

[0048] Preparation example of dual MOF composite nanotubes

[0049] Preparation Example 1

[0050] The dual MOF composite nanotubes are prepared by the following method:

[0051] A. Immerse 1 kg of halloysite nanotube powder in 8 kg of 3% γ-aminopropyltriethoxysilane ethanol solution, reflux with stirring at 70°C for 3 h, filter, wash with ethanol three times, and dry at 60°C for 12 h to obtain activated halloysite nanotubes;

[0052] B. Dissolve 1 kg of copper nitrate and 1.2 kg of trimesic acid in 8 kg of N,N-dimethylformamide and mix them ultrasonically for 30 minutes to obtain a copper-based precursor solution; disperse 1 kg of activated halloysite nanotubes in the copper-based precursor solution, ultrasonically treat for 1 hour, transfer the solution to a hydrothermal reactor, react at 110°C for 10 hours, cool, wash with ethanol three times, and vacuum dry at 60°C for 8 hours to obtain halloysite nanotubes with copper trimesic acid loaded in the inner cavity;

[0053] C. Dissolve 1 kg of cobalt nitrate hexahydrate and 3 kg of 2-methylimidazole in 20 kg of methanol and stir until completely dissolved to obtain a cobalt-based precursor solution. Disperse 1 kg of halloysite nanotubes with an inner cavity loaded with copper trimesic acid in the cobalt-based precursor solution. Stir and react at room temperature for 20 hours, then centrifuge at 8000 rpm. Wash the solid product three times with methanol and dry it at 60°C for 10 hours to obtain dual-MOF composite nanotubes.

[0054] Preparation Example 2

[0055] The dual MOF composite nanotubes are prepared by the following method:

[0056] A. Immerse 1 kg of halloysite nanotube powder in 9 kg of 4% γ-aminopropyltriethoxysilane ethanol solution, reflux with stirring at 75°C for 4 h, filter, wash with ethanol three times, and dry at 60°C for 12 h to obtain activated halloysite nanotubes;

[0057] B. Dissolve 1 kg of copper nitrate and 1.4 kg of trimesic acid in 9 kg of N,N-dimethylformamide and mix them ultrasonically for 30 minutes to obtain a copper-based precursor solution; disperse 1 kg of activated halloysite nanotubes in the copper-based precursor solution, ultrasonically treat for 1 hour, transfer the mixture to a hydrothermal reactor, react at 115°C for 11 hours, cool, wash with ethanol three times, and vacuum dry at 60°C for 8 hours to obtain halloysite nanotubes with copper trimesic acid loaded in the inner cavity;

[0058] C. Dissolve 1 kg of cobalt nitrate hexahydrate and 3.5 kg of 2-methylimidazole in 23 kg of methanol and stir until completely dissolved to obtain a cobalt-based precursor solution. Disperse 1 kg of halloysite nanotubes with an inner cavity loaded with copper trimesic acid in the cobalt-based precursor solution. Stir and react at room temperature for 22 hours, then centrifuge at 8000 rpm. Wash the solid product three times with methanol and dry it at 60°C for 10 hours to obtain dual-MOF composite nanotubes.

[0059] Preparation Example 3

[0060] The dual MOF composite nanotubes are prepared by the following method:

[0061] A. Immerse 1 kg of halloysite nanotube powder in 10 kg of 5% γ-aminopropyltriethoxysilane ethanol solution, reflux with stirring at 80°C for 5 h, filter, wash with ethanol three times, and dry at 60°C for 12 h to obtain activated halloysite nanotubes;

[0062] B. Dissolve 1 kg of copper nitrate and 1.5 kg of trimesic acid in 10 kg of N,N-dimethylformamide and mix them ultrasonically for 30 minutes to obtain a copper-based precursor solution; disperse 1 kg of activated halloysite nanotubes in the copper-based precursor solution, ultrasonically treat for 1 hour, transfer the solution to a hydrothermal reactor, react at 120°C for 12 hours, cool, wash with ethanol three times, and vacuum dry at 60°C for 8 hours to obtain halloysite nanotubes with copper trimesic acid loaded in the inner cavity;

[0063] C. Dissolve 1 kg of cobalt nitrate hexahydrate and 4 kg of 2-methylimidazole in 25 kg of methanol and stir until completely dissolved to obtain a cobalt-based precursor solution. Disperse 1 kg of halloysite nanotubes with an inner cavity loaded with copper trimesic acid in the cobalt-based precursor solution. Stir and react at room temperature for 24 hours, then centrifuge at 8000 rpm. Wash the solid product three times with methanol and dry it at 60°C for 10 hours to obtain dual-MOF composite nanotubes.

[0064] Preparation Example 4

[0065] The difference between the dual-MOF composite nanotubes and Preparation Example 1 is that the halloysite nanotube powder is not activated in this Preparation Example.

[0066] Preparation Example 5

[0067] The halloysite nanotubes with copper trimesate loaded in the inner cavity are different from those in Preparation Example 1 in that step C is not performed.

[0068] Preparation Example 6

[0069] The halloysite nanotubes with cobalt dimethylimidazolium loaded on their outer walls are different from those in Preparation Example 1 in that step B is not performed, and in step C, activated halloysite nanotubes are directly used to participate in the loading reaction.

[0070] Preparation example of modified diatomaceous earth

[0071] Preparation Example 7

[0072] 10 kg of diatomaceous earth and 1 kg of stearic acid were mixed, stirred and reacted at 70° C. for 2 h, and after cooling, transferred to a ball mill and ball-milled at 300 rpm for 1 h to obtain modified diatomaceous earth.

[0073] Preparation Example 8

[0074] 12 kg of diatomaceous earth and 1 kg of stearic acid were mixed, stirred and reacted at 75° C. for 2.5 hours, and after cooling, transferred to a ball mill and ball milled at 300 rpm for 1 hour to obtain modified diatomaceous earth.

[0075] Preparation Example 9

[0076] 15 kg of diatomaceous earth and 1 kg of stearic acid were mixed, stirred and reacted at 80° C. for 3 h, and after cooling, transferred to a ball mill and ball milled at 400 rpm for 1 h to obtain modified diatomaceous earth.

[0077] Example

[0078] Example 1

[0079] A water-resistant putty powder for interior walls, the raw material components and amounts of which are shown in Table 1, wherein the double MOF composite nanotubes are the double MOF composite nanotubes prepared in Preparation Example 1; the modified diatomaceous earth is the modified diatomaceous earth prepared in Preparation Example 7; the polypropylene fiber has an average length of 3 mm and a diameter of 15 μm; the defoamer is a polyether-modified silicon defoamer, the dispersant is sodium polyacrylate, and the mildew inhibitor is sodium diacetate.

[0080] A water-resistant putty powder for interior walls is prepared by the following method:

[0081] S1. Put sulphoaluminate cement, nano-heavy calcium powder, silica fume, modified diatomaceous earth, double MOF composite nanotubes, nano-titanium dioxide, and mildew inhibitor into a dry powder mixer and stir at 200 rpm for 15 min to obtain a premix;

[0082] S2. Mix the polypropylene fiber with the premix, add a defoamer and a dispersant, stir at 800 rpm for 8 minutes, and then pack into moisture-proof packaging bags to obtain interior wall water-resistant putty powder.

[0083] Example 2

[0084] A water-resistant putty powder for interior walls, the raw material components and amounts of which are shown in Table 1, wherein the double MOF composite nanotubes are selected from the double MOF composite nanotubes prepared in Preparation Example 2; the modified diatomaceous earth is selected from the modified diatomaceous earth prepared in Preparation Example 8; the polypropylene fiber has an average length of 4 mm and a diameter of 18 μm; the defoamer is a polyether-modified silicon defoamer, the dispersant is sodium polyacrylate, and the mildew inhibitor is sodium diacetate.

[0085] A water-resistant putty powder for interior walls is prepared by the following method:

[0086] S1. Sulphoaluminate cement, nano-heavy calcium powder, silica fume, modified diatomaceous earth, double MOF composite nanotubes, nano-titanium dioxide, and mildew inhibitor were put into a dry powder mixer and stirred at 250 rpm for 12 min to obtain a premix;

[0087] S2. Mix the polypropylene fiber with the premix, add a defoamer and a dispersant, stir at 900 rpm for 6 minutes, and then pack into moisture-proof packaging bags to obtain interior wall water-resistant putty powder.

[0088] Example 3

[0089] A water-resistant putty powder for interior walls, the raw material components and amounts of which are shown in Table 1, wherein the double MOF composite nanotubes are selected from the double MOF composite nanotubes prepared in Preparation Example 3; the modified diatomaceous earth is selected from the modified diatomaceous earth prepared in Preparation Example 9; the polypropylene fiber has an average length of 5 mm and a diameter of 20 μm; the defoamer is a polyether-modified silicon defoamer, the dispersant is sodium polyacrylate, and the mildew inhibitor is sodium diacetate.

[0090] A water-resistant putty powder for interior walls is prepared by the following method:

[0091] S1. Put sulphoaluminate cement, nano-heavy calcium powder, silica fume, modified diatomaceous earth, double MOF composite nanotubes, nano-titanium dioxide, and mildew inhibitor into a dry powder mixer and stir at 300 rpm for 10 min to obtain a premix;

[0092] S2. Mix the polypropylene fiber with the premix, add a defoamer and a dispersant, stir at 1000 rpm for 5 minutes, and then pack into moisture-proof packaging bags to obtain interior wall water-resistant putty powder.

[0093] Table 1 Raw material components and proportions of putty powder in Examples 1-3 (kg)

[0094]

[0095] Example 4

[0096] A water-resistant putty powder for interior walls is different from Example 1 in that the double MOF composite nanotubes in this example are the double MOF composite nanotubes prepared in Preparation Example 4.

[0097] Example 5

[0098] A water-resistant putty powder for interior walls, which differs from Example 1 in that: in this embodiment, the average length of the polypropylene fiber is 10 mm and the diameter is 20 μm.

[0099] Example 6

[0100] A water-resistant putty powder for interior walls, which differs from Example 1 in that wood sulfonate is used as a dispersant in this example.

[0101] Comparative Example

[0102] Comparative Example 1

[0103] Putty powder was prepared according to Example 1 in the patent application document with publication number CN103881456A, entitled "A latex exterior wall water-resistant putty powder."

[0104] Comparative Example 2

[0105] A water-resistant putty powder for interior walls, which differs from Example 1 in that: no double MOF composite nanotubes are added to the raw materials of this comparative example, and the difference is supplemented by sulphoaluminate cement.

[0106] Comparative Example 3

[0107] A water-resistant putty powder for interior walls is different from Example 1 in that an equal amount of unmodified diatomaceous earth is used in the raw materials of this comparative example instead of the modified diatomaceous earth.

[0108] Comparative Example 4

[0109] A water-resistant putty powder for interior walls is different from Example 1 in that the double MOF composite nanotubes in this comparative example are the double MOF composite nanotubes prepared in Preparation Example 5.

[0110] Comparative Example 5

[0111] A water-resistant putty powder for interior walls is different from Example 1 in that the double MOF composite nanotubes in this comparative example are the double MOF composite nanotubes prepared in Preparation Example 6.

[0112] Performance testing

[0113] Test samples: putty powders prepared in Examples 1-6 and Comparative Examples 1-5.

[0114] Test items:

[0115] 1. Crack resistance

[0116] According to the method specified in GB / T23455-2009 "Flexible Putty for Exterior Walls", observe whether cracks appear on the surface of the putty layer. The test results are shown in Table 2.

[0117] 2. Water resistance and anti-seepage performance test

[0118] With reference to GB / T23445-2009 “Polymer Cement Waterproof Coating”, the specimen was mounted on the anti-seepage tester. The pressure was increased from 0.1 MPa and increased by 0.05 MPa every 30 minutes until water seepage appeared on the surface of the specimen. The maximum anti-seepage pressure was recorded. The test results are shown in Table 2.

[0119] 3. Air permeability test

[0120] Water vapor transmission rate (WVT) is tested by referring to the cupping method in GB / T17146-1997, Test Method for Water Vapor Transmission of Building Materials. The WVT is generally required to be ≥ 0.8 g / (m2·d). A higher value indicates better air permeability. The test results are shown in Table 2.

[0121] Table 2 Test results

[0122]

[0123] As can be seen from Table 2, the water resistance and anti-permeability performance of the putty powders of Examples 1-3 are all over 1.2 MPa, indicating that the dimethyl imidazole cobalt loaded on the outer wall of the dual-MOF composite nanotubes works synergistically with the rigid skeleton formed by sulphoaluminate cement and silica fume to effectively block the penetration of liquid water; in terms of air permeability, the water vapor transmission rate is maintained at 2.45-2.53 g / (m 2 ·d), indicating that the putty powder has good air permeability, which is due to the tubular structure of halloysite nanotubes providing a directional transmission channel for water vapor, and the through-network formed by the pores of modified diatomite and dual MOF composite nanotubes further enhances the water vapor diffusion efficiency, achieving a simultaneous improvement in water resistance and air permeability.

[0124] The difference between Example 4 and Example 1 is that the dual MOF composite nanotubes were not activated. The water resistance and anti-permeability performance dropped to 1.13 MPa, and the water vapor transmission rate also dropped to 1.95 g / (m 2 d). This is because the coordination effect between the unactivated halloysite nanotubes and the MOF is weak, resulting in the weak loading of copper trimesic acid and cobalt dimethylimidazole. As a result, they cannot fully exert their functions of selectively adsorbing water vapor and blocking liquid water. At the same time, the synergistic effect with the modified diatomite pore network is affected, ultimately resulting in a decrease in water resistance and air permeability.

[0125] The difference between Example 5 and Example 1 is that the length of the polypropylene fiber is increased to 10 mm. The water resistance and anti-permeability performance are slightly reduced to 1.20 MPa, and the water vapor transmission rate is reduced to 2.35 g / (m 2 d). Excessively long polypropylene fibers are prone to entanglement. Although they can still bridge microcracks, they form some agglomerates inside the putty, blocking some water vapor transmission channels and weakening the breathable network constructed by the modified diatomaceous earth and dual-MOF composite nanotubes, thus negatively affecting air permeability.

[0126] Example 6: The dispersant was replaced with wood sulfonate. One crack appeared, the water resistance and anti-permeability performance dropped to 1.02 MPa, and the water vapor transmission rate dropped to 1.71 g / (m 2 d). The low dispersion efficiency of wood sulfonate results in uneven dispersion of nanomaterials, leading to an uneven internal structure of the putty, stress concentration points that cause cracks, and also affects the water resistance and air permeability of the putty.

[0127] Comparative Example 1 uses the existing technical formula, and 3 cracks appear. The water resistance and anti-permeability performance is only 0.85MPa, and the water vapor transmission rate is as low as 0.31g / (m 2 d). This technology forms a dense waterproof layer through a high content of cementitious materials. Although it has a certain degree of water resistance, it completely closes the pores of the putty layer, resulting in extremely poor air permeability and the inability to discharge water vapor inside the wall.

[0128] Comparative Example 2 did not add double MOF composite nanotubes, and the water resistance and anti-permeability performance were 0.96 MPa and the water vapor transmission rate was 1.24 g / (m 2 d). Without the directional water conduction and selective water blocking effects of the dual MOF composite nanotubes, relying solely on cementitious materials such as sulfoaluminate cement and modified diatomaceous earth is difficult to effectively block liquid water and promote water vapor diffusion, resulting in lower water resistance and air permeability than Example 1.

[0129] The double MOF composite nanotubes of comparative example 4 only have copper trimesic acid loaded in the inner cavity, and the water resistance and anti-permeability performance are 1.06 MPa and the water vapor transmission rate is 1.32 g / (m 2d). The lack of the hydrophobic and water-blocking effect of dimethylimidazolate cobalt on the outer wall makes it impossible to effectively block liquid water. At the same time, the single inner wall adsorption function makes it difficult to achieve efficient water vapor transmission. Both performances are lower than those of Example 1, indicating that the coordinated loading of the inner and outer walls of the dual-MOF composite nanotubes is crucial to improving water resistance and air permeability. The dual-MOF composite nanotubes of Comparative Example 5 only have dimethylimidazolate cobalt loaded on the outer wall, with a water resistance and anti-permeability performance of 1.08 MPa and a water vapor transmission rate of 1.37 g / (m 2 d). The lack of the water vapor adsorption function of copper trimesic acid on the inner wall cannot fully promote water vapor diffusion. Although it has a certain hydrophobic and water-blocking ability, the overall water resistance and air permeability are still lower than those of Example 1, further verifying the necessity of the synergistic effect between the inner and outer walls of the dual-MOF composite nanotubes.

[0130] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A water-resistant putty powder for interior walls, characterized in that: The invention is made from the following raw materials in parts by weight: 18-22 parts of sulphoaluminate cement; 35-45 parts of nano calcium powder; 12-18 parts of silica fume; 3-6 parts of dual-MOF composite nanotubes; 8-12 parts of modified diatomaceous earth; Polypropylene fiber 0.2-0.4 parts; 0.5-1 part of nano titanium dioxide; 0.5-1 part of defoaming agent; Dispersant 0.5-1 part; 0.5-1 part of mildew inhibitor; The dual-MOF composite nanotubes are obtained by loading copper trimesic acid in the inner cavity of halloysite nanotubes and loading cobalt dimethylimidazole on the outer wall. Amino groups are introduced on the surface of the halloysite nanotubes by a silane coupling agent to enhance the coordination effect with MOF, thereby enhancing the stability of the structural performance of the dual-MOF composite nanotubes. The modified diatomaceous earth is obtained by modifying diatomaceous earth with stearic acid; The polypropylene fiber has a diameter of 15-20 μm and a length of 3-5 mm; The dispersant is sodium polyacrylate.

2. A water-resistant putty powder for interior walls according to claim 1, characterized in that: The dual-MOF composite nanotubes are prepared by the following method: A. Immerse the halloysite nanotube powder in an ethanol solution of a silane coupling agent, reflux and stir at 70-80° C. for 3-5 hours, filter, wash with ethanol, and dry to obtain activated halloysite nanotubes; B. Dispersing the activated halloysite nanotubes in a copper-based precursor solution, ultrasonically treating for 1-3 hours, then transferring to a hydrothermal reactor, reacting at 110-120° C. for 10-12 hours, then washing with ethanol and drying to obtain the halloysite nanotubes with copper trimesic acid loaded in the inner cavity; C. Halloysite nanotubes with copper trimesic acid loaded in the inner cavity are dispersed in a cobalt-based precursor solution, stirred and reacted at room temperature for 20-24 hours, and then centrifuged. The solid product is washed and dried to obtain dual-MOF composite nanotubes.

3. A water-resistant putty powder for interior walls according to claim 2, characterized in that, The copper-based precursor solution is prepared by dissolving copper nitrate and trimesic acid in N,N-dimethylformamide, and performing ultrasonic mixing to obtain the copper-based precursor solution.

4. A water-resistant putty powder for interior walls according to claim 3, characterized in that, The mass ratio of the copper nitrate, trimesic acid and N,N-dimethylformamide is 1:(1.2-1.5):(8-10).

5. A water-resistant putty powder for interior walls according to claim 2, characterized in that, The cobalt-based precursor solution is prepared by dissolving cobalt nitrate hexahydrate and 2-methylimidazole in methanol, and stirring until the cobalt-based precursor solution is completely dissolved.

6. A water-resistant putty powder for interior walls according to claim 5, characterized in that: The mass ratio of the cobalt nitrate hexahydrate, 2-methylimidazole and methanol is 1:(3-4):(20-25).

7. A water-resistant putty powder for interior walls according to claim 2, characterized in that, The mass ratio of the halloysite nanotube powder to the ethanol solution of the silane coupling agent is 1:(8-10), and the mass concentration of the ethanol solution of the silane coupling agent is 3%-5%.

8. A water-resistant putty powder for interior walls according to claim 2, characterized in that, The modified diatomaceous earth is prepared by the following method: Diatomaceous earth and stearic acid are mixed in a mass ratio of (10-15):1, stirred and reacted at 70-80°C for 2-3h, and ball-milled after cooling to obtain modified diatomaceous earth.

9. A method for preparing the water-resistant putty powder for interior walls according to any one of claims 1 to 8, characterized in that: The steps include: S1. Add sulphoaluminate cement, nano-heavy calcium powder, silica fume, modified diatomaceous earth, double MOF composite nanotubes, nano-titanium dioxide, and mildew inhibitor into a dry powder mixer and stir at 200-300 rpm for 10-15 minutes to obtain a premix; S2. Mix the polypropylene fiber with the premix, add a defoamer and a dispersant, stir at 800-1000 rpm for 5-8 minutes, and then pack into moisture-proof packaging bags to obtain interior wall water-resistant putty powder.

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