Self-repairing coating film as well as preparation method and application thereof

Abstract

The invention discloses a self-repairing coating film as well as a preparation method and application thereof, and belongs to the field of functional composite materials and cultural heritage protection. The preparation method disclosed by the invention comprises the following steps: mixing methyl trimethoxy silane and vinyl trimethoxy silane to obtain a composite silicon resin matrix; adding modified nano Ca (OH) 2, modified nano TiO2, aspartic acid and a dispersing agent into the composite silicon resin matrix, and mixing to obtain coating slurry; and coating the surface of a base material with the coating slurry, and curing to obtain the self-repairing coating. According to the preparation method, carbonation self-repairing of nano Ca (OH) 2 is taken as a core, aspartic acid is taken as a CaCO3 crystal form regulating agent and is combined with a composite matrix of MTMS and VTMS and the dispersion improvement effect of KH-550, so that an efficient synergistic mechanism is formed, multiple effects of micro-crack repairing, adhesive force improvement, uniform performance and the like are realized, and the preparation method is suitable for long-acting protection of brick soil historic buildings.

Description

TECHNICAL FIELD

[0001] The present application belongs to the cross field of functional composite materials and cultural heritage protection, and particularly relates to a self-repairing coating film and a preparation method and application thereof. BACKGROUND

[0002] Brick clay ancient buildings are non-renewable cultural heritage, and the performance of the surface protective coating is crucial to the preservation state of the cultural relics. At present, the industry urgently needs a new type of intelligent protective coating material with core of nano Ca(OH)2 carbonation self-repairing to meet the long-term protection needs of ancient buildings. Traditional coatings have problems of poor volume stability, easy agglomeration of nano fillers, weak interfacial adhesion with the substrate, and no self-repairing mechanism, which seriously affect the protection effect and durability of ancient buildings.

[0003] Currently, in addition to traditional coating materials, Ca(OH)2-based self-repairing materials applied in the field of concrete are tried to be used for ancient building protective coating systems, expecting to realize coating damage repair by means of carbonation reaction. The application of this material has many problems, such as poor interfacial compatibility of nano Ca(OH)2 with the silicone matrix and lack of effective modification strategy, poor dispersion and easy agglomeration; the crystal form of CaCO3 generated by carbonation is uncontrollable, and the filling performance of calcite type crystals is poor; the permeability of the silicone matrix to CO2 is insufficient, and the contradiction between the crosslinking density of the single silicone system and the gas permeability is prominent, resulting in low repair efficiency and limited effect.

[0004] Therefore, it is urgent to develop a new type of intelligent protective coating material with core of nano Ca(OH)2 carbonation self-repairing, high adhesion, and uniform dispersion of nano fillers to meet the actual needs of long-term protection of ancient buildings. SUMMARY

[0005] The present application aims to overcome the defects of the prior art and provide a self-repairing coating film and a preparation method thereof to solve the key technical problems of the self-repairing function, volume stability, and interfacial adhesion of the protective coating of ancient buildings.

[0006] To achieve the above-mentioned purpose, the first aspect of the present application provides a preparation method of a self-repairing coating film, comprising the following steps: mixing methyltrimethoxysilane and vinyltrimethoxysilane to obtain a composite silicone resin matrix; adding modified nano Ca(OH)2, modified nano TiO2, aspartic acid, and a dispersing agent into the composite silicone resin matrix to obtain a coating film slurry; coating the coating film slurry on the surface of a substrate and curing to obtain a self-repairing coating film.

[0007] Furthermore, the modified nano-Ca(OH)2 has a mass percentage of 10%~15% in the coating slurry; the modified nano-TiO2 has a mass percentage of 8%~12% in the coating slurry; the aspartic acid has a mass percentage of 2%~5% in the coating slurry; and the dispersant has a mass percentage of 3%~7% in the coating slurry.

[0008] Furthermore, the mass ratio of methyltrimethoxysilane to vinyltrimethoxysilane is (5~7):1.

[0009] Furthermore, the modified nano-Ca(OH)2 was prepared by reacting γ-aminopropyltriethoxysilane with nano-Ca(OH)2.

[0010] Furthermore, the modified nano-TiO2 was prepared by reacting γ-aminopropyltriethoxysilane with nano-TiO2.

[0011] Furthermore, the preparation process of modified nano Ca(OH)2 is as follows: nano Ca(OH)2 and silane coupling agent are added to anhydrous ethanol at a mass ratio of 100:(3~5), and the mixture is subjected to ultrasonic and centrifugal treatment to obtain a precipitate, which is then dried to obtain modified nano Ca(OH)2. Preparation process of modified nano-TiO2: Nano-TiO2 and silane coupling agent are added to anhydrous ethanol at a mass ratio of 100:(3~5), and the mixture is subjected to ultrasonic and centrifugal treatment to obtain a precipitate, which is then dried to obtain modified nano-TiO2.

[0012] Furthermore, the dispersant includes one or more of the following: sodium salt of acrylic homopolymer, sodium salt of acrylic-maleic copolymer, sodium polyacrylate, polycarboxylic acid dispersant, naphthalenesulfonic acid formaldehyde condensate salt, metastyrene sulfonate, lignin sulfonate, polyvinylpyrrolidone, polyvinyl alcohol, and polyoxyethylene-polyoxypropylene block copolymer.

[0013] Further, the coating slurry is applied to the surface of the substrate and cured, specifically as follows: Apply 2-3 layers of the coating slurry to the substrate surface, with an interval of 10-20 minutes between each layer; pre-cure at room temperature for 20-60 minutes; and then cure at a constant temperature of 60-80℃ for 20-40 minutes.

[0014] A second aspect of the present invention provides a self-healing coating film prepared according to the above-described method for preparing a self-healing coating film.

[0015] The third aspect of this invention provides the application of the above-mentioned self-healing coating in the field of cultural relic protection.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The preparation method provided by this invention uses a mixture of methyltrimethoxysilane (MTMS) and vinyltrimethoxysilane (VTMS) to prepare a composite silicone resin matrix, breaking the limitations of a single silicone resin system. The introduction of VTMS not only enhances the adhesion between the coating and the substrate by strengthening the bond between the coating and the substrate through flexible segments and functional groups, but also improves the permeability of the matrix to CO2, creating favorable conditions for subsequent self-healing reactions. Modified nano-Ca(OH)2 and modified nano-TiO2 are used to solve the root cause problem of poor compatibility between nanoparticles and the organosilicon matrix, ensuring uniform and stable coating performance. With nano-Ca(OH)2 carbonation self-healing as the core, aspartic acid is introduced into the composite matrix of MTMS and VTMS as a CaCO3 crystal form regulator, improving interfacial adhesion and enhancing the micropore connectivity of the matrix, promoting CO2 diffusion into the crack region and accelerating the carbonation reaction. These synergistic mechanisms achieve multiple effects such as microcrack repair, improved adhesion, and uniform performance, effectively avoiding problems such as poor dispersion of nanofillers and weak adhesion between the coating and the substrate in traditional preparation methods, significantly improving the overall performance of the coating.

[0017] The self-healing coating provided by this invention is applied to the protection of cultural relics. Addressing the needs of ancient building preservation, its highly efficient self-healing function can achieve excellent macroscopic repair of microcracks of 0.1-0.2mm, and can also reduce the width and area of ​​macroscopic cracks larger than 0.2mm, preventing the penetration of corrosive media. Its high adhesion (0-1 grade) ensures that the coating is not easily detached or peeled off under conditions of temperature and humidity cycling. Its excellent UV resistance can block ultraviolet rays, protecting the substrate of ancient buildings from UV damage, comprehensively meeting the long-term protection needs of ancient buildings and solving many pain points of traditional coatings in ancient building applications. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the preparation method of Example 1 of the present invention; Figure 2 This is a diagram showing the state of the crack before repair in Embodiment 1 of the present invention; Figure 3 This is a diagram showing the effect of the self-healing coating of Embodiment 1 of the present invention on crack repair after 6 days; Figure 4 The image shows a comparison of the self-healing coating of Embodiment 1 of the present invention before (left) and after (right) crack repair. Figure 5The image shows a comparison before and after repair of cracks larger than 0.2 mm on the coating film in Embodiment 1 of the present invention. Figure 6 The transmittance of four types of self-healing coatings with different concentrations in the embodiments of the present invention is shown. Detailed Implementation

[0020] To make the technical problem to be solved, the technical solution, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0021] In this invention, the term "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0022] In this invention, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can both represent: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0023] It should be understood that in various embodiments of the present invention, the order of the above-mentioned processes does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0024] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0025] The weights of the relevant components mentioned in the embodiments of this invention can refer not only to the specific content of each component, but also to the proportional relationship between the weights of the components. Therefore, any scaling up or down of the content of the relevant components according to the embodiments of this invention is within the scope disclosed in the embodiments of this invention. Specifically, the mass described in the embodiments of this invention can be a mass unit known in the chemical industry, such as μg, mg, g, or kg.

[0026] Unless otherwise stated, all percentages in this document are by mass; temperature is in °C; dimensions are in mm and thickness is in μm; and rotation speed is in rpm.

[0027] This invention provides a method for preparing a self-healing coating, comprising the following steps: A composite silicone resin matrix is ​​obtained by mixing methyltrimethoxysilane and vinyltrimethoxysilane. Modified nano-Ca(OH)2, modified nano-TiO2, aspartic acid, and dispersant are added to a composite silicone resin matrix and mixed to obtain a coating slurry; The coating slurry is applied to the surface of the substrate and cured to obtain a self-healing coating.

[0028] The self-healing function of the self-healing coating provided by this invention is based on a chemical-physical synergistic mechanism: When microcracks develop in the coating, the exposed nano-Ca(OH)2 undergoes a carbonation reaction with environmental CO2 and water vapor as follows:

[0029] The generated CaCO3 crystals are deposited in situ within the crack, filling the crack space and achieving both physical sealing and mechanical healing.

[0030] Aspartic acid plays a role in crystal form regulation: As a biomineralization regulator, its functional groups (-COOH, -NH2) selectively adsorb onto specific crystal faces of CaCO3 crystal nuclei, inhibiting the growth of thermodynamically stable calcite-type crystals and inducing the formation of kinetically controlled aragonite / spherulite-type CaCO3. The latter two exhibit needle-like / spherical micromorphologies, large specific surface area, and high degree of cross-linking, resulting in significantly better crack filling density and bonding strength than calcite, thus greatly improving repair efficiency.

[0031] Synergistic function of MTMS-VTMS composite matrix: MTMS provides high crosslinking density and network rigidity, while the flexible segments and vinyl functional groups introduced by VTMS enhance the interfacial adhesion between the matrix and the substrate, and enhance the micropore connectivity of the matrix, promote the diffusion of CO2 into the crack region, and accelerate the carbonation reaction.

[0032] Interfacial modification effect of silane coupling agents: One end of coupling agents such as KH-550 reacts with the hydroxyl groups on the surface of nanoparticles (Ca(OH)2, TiO2), while the other end (amino group) has good compatibility with the organosilicon matrix, forming a "molecular bridge". This solves the problem of poor interfacial compatibility between nanofillers and organic matrices, ensuring that nano-Ca(OH)2 is uniformly dispersed in the matrix and providing reactive sites for efficient self-healing.

[0033] In some embodiments of the present invention, the modified nano-Ca(OH)2 accounts for 10% to 15% of the mass percentage in the coating slurry; the modified nano-TiO2 accounts for 8% to 12% of the mass percentage in the coating slurry; the aspartic acid accounts for 2% to 5% of the mass percentage in the coating slurry; and the dispersant accounts for 3% to 7% of the mass percentage in the coating slurry. Within this range, the modified nano-Ca(OH)2 ensures a sufficient supply of raw materials for the self-healing reaction, meeting the needs of crack repair; the modified nano-TiO2 is in the high-efficiency UV-resistant range and can stably exert its UV blocking effect; the aspartic acid can precisely control the CaCO3 crystal form, avoiding insufficient dosage leading to crystal form loss or excessive dosage causing performance redundancy; and the dispersant can effectively prevent the agglomeration of nanofillers, ensuring coating uniformity.

[0034] In some embodiments of the present invention, the mass ratio of methyltrimethoxysilane to vinyltrimethoxysilane is (5~7):1. Methyltrimethoxysilane ensures the basic stability of the substrate, while vinyltrimethoxysilane provides flexible segments and functional groups. Within this range, vinyltrimethoxysilane can enhance coating adhesion and CO2 permeability without compromising the structural stability of the substrate due to its excessive proportion, thus perfectly balancing the structural strength and functional properties of the substrate and providing dual protection for the coating's adhesion performance and self-healing reaction efficiency.

[0035] In some embodiments of the present invention, the modified nano-Ca(OH)2 is nano-Ca(OH)2 modified with γ-aminopropyltriethoxysilane. The modified nano-TiO2 is nano-TiO2 modified with γ-aminopropyltriethoxysilane. Modifying nano-Ca(OH)2 and nano-TiO2 with γ-aminopropyltriethoxysilane allows the formation of a modified layer adapted to the organosilicon matrix on the surface of the nanoparticles. This modified layer significantly improves the compatibility of the two nanomaterials with the composite silicone resin matrix, completely solving the problem of easy agglomeration of nanoparticles and ensuring uniform and stable coating performance. Simultaneously, the modified nano-Ca(OH)2 can participate more efficiently in the carbonation self-healing reaction, and the modified nano-TiO2 can be more uniformly dispersed to exert its anti-UV effect, laying a solid foundation for the core functions of the coating film.

[0036] In some embodiments of the present invention, the dispersant is sodium salt of acrylic homopolymer.

[0037] In some embodiments of the present invention, the coating slurry is applied to the surface of the substrate and cured, specifically as follows: Apply 2-3 layers of the coating slurry to the substrate surface, with an interval of 10-20 minutes between layers; pre-cur at room temperature for 20-60 minutes; and cure at a constant temperature of 60-80℃ for 20-40 minutes.

[0038] In some embodiments of the present invention, the preparation process of the modified nano-Ca(OH)2 is as follows: nano-Ca(OH)2 and silane coupling agent are added to anhydrous ethanol at a mass ratio of 100:(3~5), and the mixture is subjected to ultrasonic and centrifugation to obtain a precipitate, which is then dried to obtain modified nano-Ca(OH)2; the preparation process of the modified nano-TiO2 is as follows: nano-TiO2 and silane coupling agent are added to anhydrous ethanol at a mass ratio of 100:(3~5), and the mixture is subjected to ultrasonic and centrifugation to obtain a precipitate, which is then dried to obtain modified nano-TiO2.

[0039] This invention discloses a self-healing coating, prepared according to the above-described method. The self-healing coating is applied in the field of cultural relic preservation.

[0040] To make the technical problem to be solved, the technical solution, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0041] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under standard conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications in the art, unless otherwise stated.

[0042] Example 1 The specific preparation process is as follows: Figure 1 As shown: (1) Nanopowder modification: Nano Ca(OH)2 (particle size 100nm, purity >99%) was mixed with KH-550 (3% of the mass of nano Ca(OH)2), and anhydrous ethanol (twice the mass of nano Ca(OH)2) was added. The mixture was ultrasonically treated for 30 minutes (300W, 40kHz), centrifuged (8000rpm, 10 minutes) to remove unreacted KH-550, and the precipitate was dried at 60℃ to obtain modified nano Ca(OH)2. OH)2, set aside; mix nano-TiO2 (anatase type, particle size 20-30nm, purity >99%) with KH-550 (3% of the mass of nano-TiO2), add anhydrous ethanol (twice the mass of nano-TiO2), sonicate for 30 minutes (power 300W, frequency 40kHz), centrifuge (8000rpm, 10 minutes) to remove unreacted KH-550, and dry the precipitate at 60℃ to obtain modified nano-TiO2, set aside.

[0043] (2) Prepolymerization of resin matrix: MTMS and VTMS are mixed in a glass container at a mass ratio of 6:1 and magnetically stirred (200 rpm, 5 minutes) to obtain a composite silicone resin matrix and form a silanol network.

[0044] (3) Preparation of composite coating slurry: In the composite silicone resin matrix obtained in step (2), the modified nano Ca(OH)2 powder (12% by mass) prepared in step (1) is slowly added to avoid clumping; the modified nano TiO2 powder (10% by mass) prepared in step (1) is added in batches, and each batch is stirred for 2 minutes; the sodium salt of acrylic homopolymer (5% by mass) is added dropwise; the aspartic acid powder (3% by mass) is added and stirred until completely dissolved; the above mixture is magnetically stirred (1000 rpm, 1 hour) and then ultrasonically treated for 30 minutes to obtain the coating slurry.

[0045] (4) Substrate pretreatment: Applicable substrates include porous inorganic substrates such as brick, soil, sandstone, and limestone. For salt-containing substrates, it is recommended to pre-treat with desalination; for substrates with high water absorption, it is recommended to perform a base seal with diluted precursor (reducing solids content by 30-50%) before coating. Remove dust and debris from the substrate surface with a soft brush; wipe the substrate surface in one direction with a lint-free cloth soaked in anhydrous ethanol, repeating 3 times; rinse with deionized water and dry at 60°C.

[0046] (5) Coating and Curing: Add 4-5 drops of the coating slurry obtained in step (3) to the pretreated substrate, scrape at a 45° angle, apply 3 layers with a 15-minute interval between each layer; pre-cur at room temperature for 30 minutes; cure at a constant temperature of 70°C for 30 minutes, and allow to cool naturally to room temperature to obtain a self-healing coating. For comparison, the repair effect of the sample is as follows: Figure 2 and Figure 3 As shown.

[0047] Example 2 The preparation method of Example 2 is basically the same as that of Example 1, except that: in step (2), the mass ratio of MTMS to VTMS is 5:1; in step (3), the mass percentage of modified nano Ca(OH)2 is 15%, the mass percentage of modified nano TiO2 is 12%, the mass percentage of acrylic acid-maleic acid copolymer sodium salt is 7%, and the mass percentage of aspartic acid is 5%; in step (5), the constant temperature curing temperature is 80℃ and the curing time is 40 minutes.

[0048] Example 3 The preparation method of Example 3 is basically the same as that of Example 1, except that: in step (2), the mass ratio of MTMS to VTMS is 7:1; in step (3), the mass percentage of modified nano Ca(OH)2 is 10%, the mass percentage of modified nano TiO2 is 8%, the mass percentage of sodium polyacrylate is 3%, and the mass percentage of aspartic acid is 2%; in step (5), the constant temperature curing temperature is 60℃ and the curing time is 20 minutes.

[0049] Comparative Example 1 The preparation method of Comparative Example 1 differs from that of Example 1 in that VTMS is not added, and the mass percentage of MTMS is increased accordingly (i.e., VTMS in the MTMS:VTMS ratio is 0).

[0050] Comparative Example 2 The preparation method of Comparative Example 2 differs from that of Example 1 in that aspartic acid is not added.

[0051] Comparative Example 3 The difference between the preparation method of Comparative Example 3 and Example 1 is that the nanoparticles (Ca(OH)2 and TiO2) are not modified by the silane coupling agent in step (1), but the original powder is used directly.

[0052] Performance testing Test Example 1: Adhesion Test Test Method: Coating adhesion was tested using the cross-cut test according to GB / T9286-2021 standard. Six 1mm x 1mm squares were drawn on the coating surface. Adhesive tape was applied and then quickly peeled off. The degree of coating peeling was observed and rated from 0 to 5 (0 being the best and 5 the worst). Test results are shown in Table 1. Table 1 Adhesion test results

[0053] Results Analysis: The adhesion of Examples 1-3 all reached grade 0-1, significantly better than the comparative examples. The adhesion of Comparative Example 1 (without VTMS) dropped to grade 3, proving that the introduction of VTMS is crucial for improving adhesion. Comparative Example 3 (unmodified) had the worst adhesion (grade 4), proving that the modification with silane coupling agent has a significant effect on improving interfacial bonding.

[0054] Test Example 2: Self-Healing Performance Test Testing methods: To test the repair effect of the present invention, both macroscopic and microscopic quantitative methods were used for characterization.

[0055] Macroscopic Repair (0.1-0.2mm Crack) Test Method: A 0.1-0.2mm wide crack was etched into the coating, penetrating it, and allowed to stand undisturbed for three days to allow self-repair. Test Results: The coating film prepared in Example 1 was used for testing. Figure 4 (Comparison of before (left) and after (right) repair images) shows that after repair, no visible cracks are observed with the naked eye, and there are no signs of peeling or delamination on the coating surface, indicating good adhesion.

[0056] Quantitative Repair (>0.2mm Crack) Test Method: To objectively evaluate the repair effect of macroscopic cracks, the coating of Example 1 was prepared on a smooth glass substrate, and three cracks with a width >0.2mm were etched. Quantitative analysis was performed by measuring the width and area of ​​the cracks before and after repair. The repair effect is as follows:Figure 5 As shown in Table 2, the average width, standard deviation, and other data processing results of the three cracks before and after repair are as follows:

[0057] Table 2 Data before and after repair of the three cracks

[0058] Results Analysis: Figure 5 As shown in Table 2, the average widths of the three repaired cracks (0.310 mm, 0.304 mm, 0.297 mm) were significantly smaller than those before repair (0.399 mm, 0.488 mm, 0.461 mm). Figure 5 As shown, this method also has excellent repair effects on cracks larger than 0.2 mm on rough stone substrates.

[0059] Test Example 3: UV Resistance Test Test Method: To investigate the UV absorption performance of the coating (mainly contributed by nano-TiO2), a UV fluorescence light source with wavelengths of 200-450 nm was used to test the transmittance of coating samples with different TiO2 concentrations. The concentrations of Example 1 (10% TiO2, corresponding to sample C), Example 2 (12% TiO2, concentration close to 12.5% ​​of sample D), and Example 3 (8% TiO2, concentration close to 7.5% of sample B) all fall within this test gradient range. Test preparation and results are as follows. Figure 6 As shown.

[0060] Test Results: Four groups of samples with different TiO2 concentrations (A, B, C, and D, representing 5%, 7.5%, 10%, and 12.5% ​​respectively) were selected for testing. Figure 6 As shown, the UV transmittance of the coating decreases exponentially with increasing TiO2 concentration. Sample A (5.0% TiO2) has a UV transmittance of 17.08%; Sample B (7.5% TiO2, close to 8% in Example 3) has a UV transmittance of 6.46%; Sample C (10% TiO2, i.e., Example 1) has a transmittance that decreases to 2.44%; and Sample D (12.5% ​​TiO2, i.e., Example 2) has a transmittance that decreases to 1.10%. Sample B from Example 1 (10% TiO2) had a UV transmittance of only 6.46%; Sample C from Example 2 (close to 12.5%) had a transmittance reduced to 2.44%. The coating of this invention has excellent UV resistance, effectively blocking ultraviolet rays and protecting the substrate.

[0061] Conclusion: In summary, this invention successfully prepared a protective coating with high adhesion, efficient self-healing properties, and excellent UV resistance through a ternary synergistic strategy of MTMS-VTMS composite matrix, aspartic acid crystal form regulation, and silane modification of nanoparticles.

[0062] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the invention by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the invention should be included within the scope of protection of the invention.

Claims

1. A method for preparing a self-healing coating, characterized in that, Includes the following steps: A composite silicone resin matrix is ​​obtained by mixing methyltrimethoxysilane and vinyltrimethoxysilane. Modified nano-Ca(OH)2, modified nano-TiO2, aspartic acid, and dispersant are added to a composite silicone resin matrix and mixed to obtain a coating slurry; The coating slurry is applied to the surface of the substrate and cured to obtain a self-healing coating.

2. The method for preparing the self-healing coating according to claim 1, characterized in that, The modified nano-Ca(OH)2 has a mass percentage of 10%~15% in the coating slurry; the modified nano-TiO2 has a mass percentage of 8%~12% in the coating slurry; the aspartic acid has a mass percentage of 2%~5% in the coating slurry; and the dispersant has a mass percentage of 3%~7% in the coating slurry.

3. The method for preparing the self-healing coating according to claim 1, characterized in that, The mass ratio of methyltrimethoxysilane to vinyltrimethoxysilane is (5~7):

1.

4. The method for preparing the self-healing coating according to claim 1, characterized in that, The modified nano-Ca(OH)2 was prepared by reacting γ-aminopropyltriethoxysilane with nano-Ca(OH)2.

5. The method for preparing a self-healing coating according to claim 1, characterized in that, The modified nano-TiO2 was prepared by reacting γ-aminopropyltriethoxysilane with nano-TiO2.

6. The method for preparing a self-healing coating according to claim 1, characterized in that, The preparation process of the modified nano-Ca(OH)2: Nano-Ca(OH)2 and silane coupling agent were added to anhydrous ethanol at a mass ratio of 100:(3~5), and the mixture was subjected to ultrasonic and centrifugation to obtain a precipitate, which was then dried to obtain modified nano-Ca(OH)2. Preparation process of modified nano-TiO2: Nano-TiO2 and silane coupling agent were added to anhydrous ethanol at a mass ratio of 100:(3~5), and the mixture was subjected to ultrasonic and centrifugal treatment to obtain a precipitate, which was then dried to obtain modified nano-TiO2.

7. The method for preparing a self-healing coating according to claim 1, characterized in that, The dispersant includes one or more of the following: sodium salt of acrylic acid homopolymer, sodium salt of acrylic acid-maleic acid copolymer, sodium polyacrylate, polycarboxylic acid dispersant, naphthalene sulfonate formaldehyde condensate, metastyrene sulfonate, lignin sulfonate, polyvinylpyrrolidone, polyvinyl alcohol, and polyoxyethylene-polyoxypropylene block copolymer.

8. The method for preparing a self-healing coating according to claim 1, characterized in that, The process of coating the substrate surface with the coating slurry and then curing it specifically involves: Apply 2-3 layers of the coating slurry to the substrate surface, with an interval of 10-20 minutes between each layer; pre-cur at room temperature for 20-60 minutes; and then cure at a constant temperature of 60-80℃ for 20-40 minutes.

9. A self-healing coating, characterized in that, The self-healing coating is prepared according to any one of claims 1-8.

10. The application of the self-healing coating according to claim 9 in the field of cultural relic protection.

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