A coating composition for the red walls of ancient buildings and its application

Abstract

This disclosure relates to the field of pigment technology, and more particularly to a coating composition for the red walls of ancient buildings and its application; the coating composition comprises the following components in parts by weight: 18-25 parts by weight of mineral pigment, 0.5-2 parts by weight of fibrous material, 5-10 parts by weight of polyvinyl alcohol or polyvinyl alcohol derivative, 0.2-0.5 parts by weight of montmorillonite, 0.2-0.5 parts by weight of diatomaceous earth, and 65-85 parts by weight of water. This disclosure yields a coating composition for the red walls of ancient buildings that exhibits both excellent adhesion and color retention.

Description

Technical Field

[0001] This disclosure relates to the field of pigment technology, and more particularly to a coating composition for use on the red walls of ancient buildings and its application. Background Technology

[0002] As an important symbol of traditional Chinese architecture, the red walls of ancient buildings possess both historical and cultural value as well as artistic and aesthetic value. Their protection and restoration are key issues in the field of cultural relic preservation. Red walls are exposed to the outdoor environment for extended periods, and are susceptible to damage from wind and rain, temperature and humidity changes, and ultraviolet radiation. This makes them prone to problems such as efflorescence, powdering, cracking, and color fading. Furthermore, traditional restoration coatings suffer from poor adhesion, insufficient weather resistance, and low color fidelity.

[0003] Currently, most coatings used for the restoration of red walls in ancient buildings employ chemically synthesized components, some containing titanium dioxide and carbon black. These can easily cause color distortion and residue buildup on the base layer, and their compatibility with the red brickwork is poor, leading to peeling and blistering. Natural-based coatings, on the other hand, suffer from poor dispersibility, weak mechanical properties, and limited protective effects. Furthermore, the fiber reinforcement components in existing coatings are mostly unmodified natural fibers, resulting in poor dispersibility and system synergy. Synthetic fiber modification processes are complex, making it difficult to balance environmental friendliness with restoration requirements.

[0004] To address the aforementioned issues, the development of a coating composition for ancient building red walls that is primarily based on natural materials, possesses excellent adhesion, weather resistance, and color reproduction, and conforms to the principles of cultural relic protection has become an urgent need in the field of ancient building restoration. Summary of the Invention

[0005] This disclosure provides a coating composition for use on the red walls of ancient buildings and its application, in order to address the shortcomings of related technologies.

[0006] According to a first aspect of the present disclosure, a coating composition for the red wall surface of ancient buildings is provided, the coating composition comprising the following components in parts by weight: 18-25 parts by weight of mineral pigment, 0.5-2 parts by weight of fiber material, 0.2-0.5 parts by weight of montmorillonite, 0.2-0.5 parts by weight of diatomaceous earth, and 65-85 parts by weight of water.

[0007] In one aspect of this disclosure, the mineral pigment includes cinnabar, ochre, and carmine; the mass ratio of the cinnabar, ochre, and carmine is selected from (3~5):(1~3):(0.5~1.5).

[0008] In one aspect of the embodiments of this disclosure, the fiber material is selected from modified or unmodified lignin fiber, modified or unmodified alkali-free chopped glass fiber, modified or unmodified bamboo fiber, or modified or unmodified hemp fiber.

[0009] In one aspect of this disclosure, the fiber material is aminated bamboo fiber; the aminated bamboo fiber is prepared by the following steps: Step 1-a: Provide bamboo fiber; pre-treat the bamboo fiber; Step 2-a: Preparation of terminal amino-branched polymers; Step 3-a: The pretreated bamboo fiber obtained in step 1-a is mixed with the terminal amino-branched polymer obtained in step 1-a, and after reaction, the amino-modified bamboo fiber is obtained.

[0010] In one aspect of this disclosure, the aminated bamboo fiber is prepared by the following steps: Step 1-a: Provide bamboo fiber. Wash, dry, crush, and pass the bamboo fiber through a 100-150 mesh sieve to obtain sieved bamboo fiber. Add the sieved bamboo fiber to a KOH solution and shake for 1-2 hours. Then remove the fiber, wash and dry it, and add it to a succinic acid solution and shake for 1-2 hours. Then remove the fiber, wash and dry it to obtain the pretreated bamboo fiber. Step 2-a: Add diethylenetriamine to the reaction vessel, control the temperature of the reaction system at 5~10℃, add water to dilute the diethylenetriamine; then add N,N-methylenebisacrylamide, and after it is completely dissolved, raise the temperature of the reaction system to 70~80℃ and react for 20~28h; after the reaction is completed, cool down and separate to obtain the terminal amino branched polymer. Step 3-a: Add the pretreated bamboo fiber to the reaction vessel, add water and glutaraldehyde solution, and stir at room temperature for 1-2 hours; then add the terminal amino-branched polymer, heat to 60-70°C, and stir for 6-12 hours; after the reaction is completed, filter, wash and dry to obtain the amino-modified bamboo fiber.

[0011] In one aspect of this disclosure, the natural dispersant coating composition further includes the following components in parts by weight: 5 to 10 parts by weight of polyvinyl alcohol or polyvinyl alcohol derivatives.

[0012] In one aspect of this disclosure, the polyvinyl alcohol derivative is selected from carboxylated trehalose-modified polyvinyl alcohol; the carboxylated trehalose-modified polyvinyl alcohol is prepared by the following steps: Step 1-b: Provide trehalose, and modify the trehalose by carboxylation to obtain carboxylated trehalose; the carboxylated trehalose has the following structural formula: Step 2-b: Add the carboxylated trehalose to water, and then stir under ice-water bath conditions. During the stirring process, add 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 4-dimethylaminopyridine. After the addition is complete, continue stirring for 1 to 1.5 hours to obtain a mixed solution. Step 3-b: Provide polyvinyl alcohol, dissolve the polyvinyl alcohol in hot water, and then cool to room temperature to obtain an aqueous solution of polyvinyl alcohol; add the aqueous solution of polyvinyl alcohol dropwise to the mixed solution obtained in step 2-b, then seal and let stand for 2-5 days. After the reaction is complete, dialyze and freeze-dry the reaction solution to obtain the carboxylated trehalose-modified polyvinyl alcohol; the reaction steps are as follows: .

[0013] In one aspect of this disclosure, step 1-b includes: Step 1-c: Provide trehalose; add the trehalose to anhydrous DMF, then place the reaction system under a nitrogen atmosphere, heat to 75~85℃ and keep stirring to obtain a mixed solution; Step 2-c: Dissolve succinic anhydride in anhydrous DMF, then add it dropwise to the mixed solution obtained in step 1-c, and then add triethylamine. Keep the reaction at the temperature for 10-20 hours. Step 3-c: After the reaction is complete, DMF is first distilled off under reduced pressure; then, a mixed precipitant containing diethyl ether and acetone is used for precipitation to obtain the carboxylated trehalose; the reaction steps are as follows: .

[0014] In one aspect of this disclosure, the coating composition further includes other additives selected from one or more of binders, cosolvents, dispersants, thickeners, film-forming agents, and fillers, and is free of titanium dioxide and carbon black.

[0015] According to a second aspect of the present disclosure, the application of the aforementioned coating composition for the red wall surface of ancient buildings in the restoration of the red wall surface of ancient buildings is provided.

[0016] In one aspect of the embodiments of this disclosure, the application scenarios include the restoration of the red walls of Ming and Qing dynasty royal buildings, the restoration of the red walls of ancient residences, the restoration of the red walls of ancient temples and monasteries, or the restoration of the red wall decorations of ancient city walls.

[0017] In one aspect of the embodiments of this disclosure, the application method is brushing, rolling, scraping, or spraying, wherein the application thickness of brushing and rolling is 0.1~0.3mm / coat, and the application thickness of spraying is 0.05~0.1mm / coat.

[0018] In one aspect of this disclosure, the application includes applying the coating composition to the red wall surface of an ancient building after performing a base treatment. The base treatment includes removing floating dust from the wall surface, removing alkali from efflorescent areas, filling cracks, and sanding and smoothing the wall surface.

[0019] The technical solutions provided by the embodiments of this disclosure may include the following beneficial effects: As can be seen from the above embodiments, this disclosure has prepared a coating composition for the red wall surface of ancient buildings that has both excellent adhesion and color retention.

[0020] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this disclosure. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below in conjunction with embodiments. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. The embodiments described herein are illustrative in nature and are used to provide a basic understanding of this application. The embodiments of this application should not be construed as limiting this application.

[0022] For the sake of brevity, this article only discloses a few specific numerical ranges. However, any lower limit can be combined with any upper limit to form an unspecified range; and any lower limit can be combined with other lower limits to form an unspecified range, just as any upper limit can be combined with any other upper limit to form an unspecified range. Furthermore, each individually disclosed point or single value can itself serve as a lower or upper limit and be combined with any other point or single value or with other lower or upper limits to form an unspecified range.

[0023] In this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0024] In this description, unless otherwise stated, "above" and "below" include the stated number.

[0025] Unless otherwise stated, the terms used in this disclosure have their common meanings as commonly understood by those skilled in the art. Unless otherwise stated, the values ​​of the parameters mentioned in this disclosure can be measured using various measurement methods commonly used in the art (e.g., they can be tested according to the methods given in the embodiments of this disclosure).

[0026] The term "about" is used to describe and indicate small variations. When used in conjunction with an event or situation, the term may refer to examples in which the event or situation occurred precisely or in examples in which the event or situation occurred very approximately. For example, when used in conjunction with numerical values, the term may refer to a range of variation less than or equal to ±10% of the numerical value, such as less than or equal to ±5%, less than or equal to ±4%, less than or equal to ±3%, less than or equal to ±2%, less than or equal to ±1%, less than or equal to ±0.5%, less than or equal to ±0.1%, or less than or equal to ±0.05%. Additionally, quantities, ratios, and other numerical values ​​are sometimes presented in range format herein. It should be understood that such range format is for convenience and brevity and should be interpreted flexibly to include not only numerical values ​​explicitly specified as range limits but also all individual numerical values ​​or subranges covered within the range, as if each numerical value and subrange were explicitly specified.

[0027] The list of items connected by the terms "at least one of," "at least one of," "at least one of," or other similar terms can mean any combination of the listed items. For example, if items A and B are listed, then the phrase "at least one of A and B" means only A; only B; or A and B. In another instance, if items A, B, and C are listed, then the phrase "at least one of A, B, and C" means only A; or only B; only C; A and B (excluding C); A and C (excluding B); B and C (excluding A); or all of A, B, and C. Item A may contain a single component or multiple components. Item B may contain a single component or multiple components. Item C may contain a single component or multiple components.

[0028] The present disclosure will be further described below by way of specific embodiments. Unless otherwise specified, all chemical reagents used in the embodiments of the present disclosure are obtained through conventional commercial means. Unless otherwise specified, all contents mentioned below are mass contents. Unless otherwise specified, it is understood that the process is carried out at room temperature.

[0029] Example Example 1:

[0030] Example 1 includes the following steps: 1. Preparation of aminated bamboo fiber: Bamboo fiber is provided. The bamboo fiber is repeatedly washed with deionized water and ethanol, then dried to constant weight in an oven at 60℃, and then pulverized and passed through a 120-mesh sieve to obtain sieved bamboo fiber. The sieved bamboo fiber is added to a 10wt% KOH solution (the solution mass is 10 times the mass of the bamboo fiber) and shaken for 1.5 hours. Then, it is removed, washed with deionized water, dried, and added to a 15wt% succinic acid solution (the solution mass is 10 times the mass of the bamboo fiber) and shaken for 1.5 hours. Finally, it is removed, washed, and dried to obtain pretreated bamboo fiber. Diethylenetriamine was added to a reaction vessel, and the temperature of the reaction system was controlled at approximately 5°C. Then, water was added to dilute the diethylenetriamine, with the mass of water being 4 times the mass of diethylenetriamine. The dilution was then carried out by magnetic stirring at a speed of 300 r / min for 15 min. Next, N,N-methylenebisacrylamide was added, with the mass of N,N-methylenebisacrylamide being 0.85 times the mass of diethylenetriamine. After complete dissolution, stirring was maintained, and the temperature of the reaction system was raised to 75°C and reacted for 24 h. After the reaction was completed, the temperature was lowered to room temperature, and anhydrous ethanol was added to the reaction solution for alcohol precipitation. The solid was then collected by vacuum filtration and dried under vacuum to obtain the terminal amino-branched polymer.

[0031] The pretreated bamboo fiber was added to deionized water at a solid-liquid ratio of 1:16, and then 5% of the mass of the pretreated bamboo fiber in a 25% glutaraldehyde solution was added. The mixture was stirred at room temperature for 2 hours. Then, 15% of the mass of the pretreated bamboo fiber in the aforementioned prepared terminal amino-branched polymer was added, the temperature was raised to 70°C, and the mixture was stirred for 8 hours. After the reaction was completed, the mixture was filtered, washed, and dried to obtain the amino-modified bamboo fiber of this embodiment.

[0032] 2. Preparation of carboxylated trehalose-modified polyvinyl alcohol: 21.0 g of trehalose was added to 450 mL of anhydrous DMF. The reaction system was then placed under a nitrogen atmosphere, heated to 80 °C, and stirred for 2 h (300 r / min) to obtain a mixed solution. 5.76 g of succinic anhydride was added to 100 mL of anhydrous DMF and then added dropwise to the aforementioned mixed solution. 8.4 g of triethylamine was then added to 50 mL of anhydrous DMF and then added dropwise to the aforementioned mixed solution. The reaction was then maintained at this temperature for 12 h. After the reaction was completed, the DMF was first distilled off under reduced pressure. Then, a mixed precipitant containing diethyl ether and acetone (diethyl ether:acetone volume ratio of 7:3) was used for precipitation. After centrifugation, the precipitate was dissolved in a small amount of DMF. The precipitation operation was repeated three times. Finally, the centrifuge tube containing the precipitate was sealed with plastic wrap and punctured, and then dried in a vacuum oven to obtain carboxylated trehalose.

[0033] 18.0 g of the prepared carboxylated trehalose was weighed and added to 200 mL of water. The mixture was then stirred in an ice-water bath. During stirring, 5.2 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 1.8 g of 4-dimethylaminopyridine were added. After the addition was complete, stirring was continued for 1.5 h to obtain a mixed solution. 72 g of polyvinyl alcohol (Mn of approximately 12000~15000, degree of alcoholysis 98%) was provided. The polyvinyl alcohol was dissolved in 1 L of hot water (approximately 90 °C) and then cooled to room temperature to obtain an aqueous solution of polyvinyl alcohol. The aqueous solution of polyvinyl alcohol was added dropwise to the mixed solution, then sealed and allowed to stand for 3 days. After the reaction was completed, the reaction solution was dialyzed (using a dialysis bag with a molecular weight of 8000) and freeze-dried to obtain the carboxylated trehalose-modified polyvinyl alcohol of this embodiment.

[0034] 3. Preparation of the coating composition of this embodiment: Cinnabar, ochre, and carmine were ground and sieved to obtain 50-mesh particles, and then mixed in a mass ratio of 5:2:1 to obtain the mineral pigment composition.

[0035] Add 25 parts by weight of mineral pigment components to 55 parts by weight of water, then add 2 parts by weight of aminated bamboo fiber, 0.3 parts by weight of montmorillonite (100 mesh) and 0.25 parts by weight of diatomaceous earth (80 mesh), wash, and obtain a suspension. Eight parts by weight of carboxylated trehalose-modified polyvinyl alcohol were added to 25 parts by weight of hot water (about 80°C). The mixture was then slowly added to the suspension while it was being stirred. After the addition was complete, the mixture was allowed to stand for 8 hours. The floating impurities were skimmed off to obtain the coating composition of this embodiment. Example 2:

[0036] Example 2 includes the following steps: 1. Preparation of pretreated bamboo fiber: Bamboo fiber is provided. The bamboo fiber is repeatedly washed with deionized water and ethanol, then dried in an oven at 60°C to constant weight, and then pulverized and passed through a 120-mesh sieve to obtain sieved bamboo fiber. The sieved bamboo fiber is added to a 10wt% KOH solution (the mass of the solution is 10 times the mass of the bamboo fiber) and shaken for 1.5 hours. Then it is taken out, washed with deionized water, dried, and added to a 15wt% succinic acid solution (the mass of the solution is 10 times the mass of the bamboo fiber) and shaken for 1.5 hours. Then it is taken out, washed, and dried to obtain pretreated bamboo fiber.

[0037] 2. Preparation of carboxylated trehalose-modified polyvinyl alcohol: 21.0 g of trehalose was added to 450 mL of anhydrous DMF. The reaction system was then placed under a nitrogen atmosphere, heated to 80 °C, and stirred for 2 h (300 r / min) to obtain a mixed solution. 5.76 g of succinic anhydride was added to 100 mL of anhydrous DMF and then added dropwise to the aforementioned mixed solution. 8.4 g of triethylamine was then added to 50 mL of anhydrous DMF and then added dropwise to the aforementioned mixed solution. The reaction was then maintained at this temperature for 12 h. After the reaction was completed, the DMF was first distilled off under reduced pressure. Then, a mixed precipitant containing diethyl ether and acetone (diethyl ether:acetone volume ratio of 7:3) was used for precipitation. After centrifugation, the precipitate was dissolved in a small amount of DMF. The precipitation operation was repeated three times. Finally, the centrifuge tube containing the precipitate was sealed with plastic wrap and punctured, and then dried in a vacuum oven to obtain carboxylated trehalose.

[0038] 18.0 g of the prepared carboxylated trehalose was weighed and added to 200 mL of water. The mixture was then stirred in an ice-water bath. During stirring, 5.2 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 1.8 g of 4-dimethylaminopyridine were added. After the addition was complete, stirring was continued for 1.5 h to obtain a mixed solution. 72 g of polyvinyl alcohol (Mn of approximately 12000~15000, degree of alcoholysis 98%) was provided. The polyvinyl alcohol was dissolved in 1 L of hot water (approximately 90 °C) and then cooled to room temperature to obtain an aqueous solution of polyvinyl alcohol. The aqueous solution of polyvinyl alcohol was added dropwise to the mixed solution, then sealed and allowed to stand for 3 days. After the reaction was completed, the reaction solution was dialyzed (using a dialysis bag with a molecular weight of 8000) and freeze-dried to obtain the carboxylated trehalose-modified polyvinyl alcohol of this embodiment.

[0039] 3. Preparation of the coating composition of this embodiment: Cinnabar, ochre, and carmine were ground and sieved to obtain 50-mesh particles, and then mixed in a mass ratio of 5:2:1 to obtain the mineral pigment composition.

[0040] Add 25 parts by weight of mineral pigment components to 55 parts by weight of water, then add 2 parts by weight of pretreated bamboo fiber, 0.3 parts by weight of montmorillonite (100 mesh) and 0.25 parts by weight of diatomaceous earth (80 mesh), wash, and obtain a suspension. Eight parts by weight of carboxylated trehalose-modified polyvinyl alcohol were added to 25 parts by weight of hot water (about 80°C). The mixture was then slowly added to the suspension while it was being stirred. After the addition was complete, the mixture was allowed to stand for 8 hours. The floating impurities were skimmed off to obtain the coating composition of this embodiment.

[0041] The main difference between Example 2 and Example 1 is that the bamboo fiber used in Example 2 was not aminated but only pretreated. Example 3:

[0042] Example 3 includes the following steps: 1. Preparation of aminated bamboo fiber: Bamboo fiber is provided. The bamboo fiber is repeatedly washed with deionized water and ethanol, then dried to constant weight in an oven at 60℃, and then pulverized and passed through a 120-mesh sieve to obtain sieved bamboo fiber. The sieved bamboo fiber is added to a 10wt% KOH solution (the solution mass is 10 times the mass of the bamboo fiber) and shaken for 1.5 hours. Then, it is removed, washed with deionized water, dried, and added to a 15wt% succinic acid solution (the solution mass is 10 times the mass of the bamboo fiber) and shaken for 1.5 hours. Finally, it is removed, washed, and dried to obtain pretreated bamboo fiber. Diethylenetriamine was added to a reaction vessel, and the temperature of the reaction system was controlled at approximately 5°C. Then, water was added to dilute the diethylenetriamine, with the mass of water being 4 times the mass of diethylenetriamine. The dilution was then carried out by magnetic stirring at a speed of 300 r / min for 15 min. Next, N,N-methylenebisacrylamide was added, with the mass of N,N-methylenebisacrylamide being 0.85 times the mass of diethylenetriamine. After complete dissolution, stirring was maintained, and the temperature of the reaction system was raised to 75°C and reacted for 24 h. After the reaction was completed, the temperature was lowered to room temperature, and anhydrous ethanol was added to the reaction solution for alcohol precipitation. The solid was then collected by vacuum filtration and dried under vacuum to obtain the terminal amino-branched polymer.

[0043] The pretreated bamboo fiber was added to deionized water at a solid-liquid ratio of 1:16, and then 5% of the mass of the pretreated bamboo fiber in a 25% glutaraldehyde solution was added. The mixture was stirred at room temperature for 2 hours. Then, 15% of the mass of the pretreated bamboo fiber in the aforementioned prepared terminal amino-branched polymer was added, the temperature was raised to 70°C, and the mixture was stirred for 8 hours. After the reaction was completed, the mixture was filtered, washed, and dried to obtain the amino-modified bamboo fiber of this embodiment.

[0044] 2. Preparation of the coating composition of this embodiment: Cinnabar, ochre, and carmine were ground and sieved to obtain 50-mesh particles, and then mixed in a mass ratio of 5:2:1 to obtain the mineral pigment composition.

[0045] Add 25 parts by weight of mineral pigment components to 55 parts by weight of water, then add 2 parts by weight of aminated bamboo fiber, 0.3 parts by weight of montmorillonite (100 mesh) and 0.25 parts by weight of diatomaceous earth (80 mesh), wash, and obtain a suspension. Eight parts by weight of polyvinyl alcohol (Mn of about 12,000 to 15,000 and degree of alcoholysis of 98%) were added to 25 parts by weight of hot water (about 80°C). The mixture was then slowly added to the suspension while it was being stirred. After the addition was complete, the mixture was allowed to stand for 8 hours. The floating impurities were skimmed off to obtain the coating composition of this embodiment.

[0046] The main difference between Example 3 and Example 1 is that the polyvinyl alcohol used in Example 3 was not modified with carboxylated trehalose. Example 4:

[0047] Example 4 includes the following steps: 1. Preparation of aminated bamboo fiber: The steps here are the same as in Example 1.

[0048] 2. Preparation of the coating composition of this embodiment: Cinnabar, ochre, and carmine were ground and sieved to obtain 50-mesh particles, and then mixed in a mass ratio of 5:2:1 to obtain the mineral pigment composition.

[0049] Add 25 parts by weight of mineral pigment components to 55 parts by weight of water, then add 2 parts by weight of aminated bamboo fiber, 0.3 parts by weight of montmorillonite (100 mesh) and 0.25 parts by weight of diatomaceous earth (80 mesh), wash, and obtain a suspension. Five parts by weight of polyvinyl alcohol (Mn of about 12,000 to 15,000, degree of alcoholysis of 98%) and three parts by weight of trehalose were added to 25 parts by weight of hot water (about 80°C). The suspension was then kept under stirring and slowly added to the suspension. After the addition was complete, the mixture was allowed to stand for 8 hours. The floating impurities were skimmed off to obtain the coating composition of this embodiment.

[0050] The main difference between Example 4 and Example 1 is that the polyvinyl alcohol used in Example 4 was not modified by carboxylated trehalose, while in Example 4, trehalose was directly added to the coating composition as a raw material. Example 5:

[0051] Example 5 includes the following steps: 1. Preparation of bamboo fiber modified with silane coupling agent: Bamboo fiber is provided. The bamboo fiber is repeatedly washed with deionized water and ethanol, then dried to constant weight in an oven at 60℃, and then pulverized and passed through a 120-mesh sieve to obtain sieved bamboo fiber. The sieved bamboo fiber is added to a 10wt% KOH solution (the solution mass is 10 times the mass of the bamboo fiber) and shaken for 1.5 hours. Then, it is removed, washed with deionized water, dried, and added to a 15wt% succinic acid solution (the solution mass is 10 times the mass of the bamboo fiber) and shaken for 1.5 hours. Finally, it is removed, washed, and dried to obtain pretreated bamboo fiber. The pretreated bamboo fiber was added to a 95% ethanol solution at a solid-liquid ratio of 1:5. Then, 15% of the mass of the pretreated bamboo fiber was added to KH550. The mixture was then heated to 65°C and stirred for 6 hours. After the reaction was completed, the bamboo fiber modified with silane coupling agent in this embodiment was obtained by filtration, washing and drying.

[0052] 2. Preparation of carboxylated trehalose-modified polyvinyl alcohol: The steps here are the same as in Example 1.

[0053] 3. Preparation of the coating composition of this embodiment: Cinnabar, ochre, and carmine were ground and sieved to obtain 50-mesh particles, and then mixed in a mass ratio of 5:2:1 to obtain the mineral pigment composition.

[0054] Add 25 parts by weight of mineral pigment components to 55 parts by weight of water, then add 2 parts by weight of bamboo fiber modified with silane coupling agent, 0.3 parts by weight of montmorillonite (100 mesh) and 0.25 parts by weight of diatomaceous earth (80 mesh), wash, and obtain a suspension. Eight parts by weight of carboxylated trehalose-modified polyvinyl alcohol were added to 25 parts by weight of hot water (about 80°C). The mixture was then slowly added to the suspension while it was being stirred. After the addition was complete, the mixture was allowed to stand for 8 hours. The floating impurities were skimmed off to obtain the coating composition of this embodiment.

[0055] The main difference between Example 5 and Example 1 is that the bamboo fiber used in Example 5 was not modified with terminal amino-branched polymer, but was modified with a silane coupling agent. Example 6:

[0056] Example 6 follows the same steps as Example 5, except that an equal mass of silane coupling agent KH560 is used instead of KH550 used in Example 5.

[0057] Comparative Example 1: Cinnabar, ochre, and carmine were ground and sieved to obtain 50-mesh particles, and then mixed in a mass ratio of 5:2:1 to obtain the mineral pigment composition.

[0058] Add 25 parts by weight of mineral pigment components to 55 parts by weight of water, then add 2 parts by weight of bamboo fiber modified with silane coupling agent, 0.3 parts by weight of montmorillonite (100 mesh) and 0.25 parts by weight of diatomaceous earth (80 mesh), wash, and obtain a suspension. Eight parts by weight of tapioca starch were added to 25 parts by weight of hot water (about 80°C). The mixture was then slowly added to the suspension while it was being stirred. After the addition was complete, the mixture was allowed to stand for 8 hours. The floating impurities were skimmed off to obtain the coating composition of this comparative example.

[0059] Performance testing: Samples from Examples 1-6 and Comparative Example 1 were coated onto the surface of commercially available blue bricks of the same size, with the dry film thickness controlled to be approximately 1.5 mm. The samples were cured for 7 days at approximately 25°C and 60% relative humidity. Then, an adhesion test was performed using the cross-cut adhesion method: 10 × 10 small grids of 2 mm × 2 mm were cut on the surface of the test sample using a sharp blade (blade angle 20-30°, blade thickness 0.43 ± 0.03 mm). The test area was cleaned of debris with a brush. The test grids were adhered to with adhesive tape with an adhesion strength of 10 ± 1 N / 25 mm. After standing for 90 seconds, one end of the tape was grasped and peeled off within 0.5-1 seconds at a 60° angle in the opposite direction. The test was repeated once. After the test, the coating peeling was examined using a 5x magnifying glass; the judgment criteria were as follows: 5B: The cut edges are completely smooth, with no loose material. 4B: A small amount of coating has peeled off at the intersection of the cuts, but the area affected by the cross-cutting should not be significantly greater than 5%; 3B: Coating peeling occurs at the intersection of cuts and / or along the edges of the cuts, with the affected cross-cut area significantly greater than 5%, but not significantly greater than 15%; 2B: The coating is partially or completely peeled off in large fragments along the cut edge, and / or partially or completely peeled off on different parts of the grid, with the affected cross-cut area significantly greater than 15%, but not significantly greater than 35%; 1B: The coating peels off in large fragments along the cut edge, and / or some squares are partially or completely detached, with the affected cross-cut area significantly greater than 35%, but not significantly greater than 65%; 0B: The degree of peeling exceeds 1B.

[0060] The specific values ​​of the samples are shown in Table 1.

[0061] Color retention test: Five test points were randomly selected on the surface of the samples from Examples 1-6 and Comparative Example 1 using a colorimeter. The CIE Lab color space parameters (L for lightness, a for red-green hue, and b for yellow-blue hue) of each sample were measured and recorded. The average value of each sample was taken as the color value parameter of each sample. .

[0062] The samples from Examples 1-6 and Comparative Example 1 were then subjected to natural exposure aging tests: natural outdoor exposure was conducted in a dry, high-UV climate zone in the north for 12 months.

[0063] Using the same colorimeter, five corresponding test points were randomly selected on the surface of the samples from Examples 1-6 and Comparative Example 1 after exposure. The CIE Lab color space parameters of the samples were measured and recorded, and the average value was taken as the color value parameters (L1, a1, b1) of the samples. The color difference ΔE after exposure and before exposure was calculated according to the CIE 1976 Lab color space color difference formula. See Table 1.

[0064] Table 1 As can be seen, the coating composition obtained in Example 1 exhibits superior performance compared to Examples 2-6 and Comparative Example 1. This is because the dispersibility of the aminated modified bamboo fiber, after grafting with hyperbranched polymers, is significantly improved, forming a uniform three-dimensional network skeleton in the coating system. This skeleton interweaves and tightly binds with the film-forming matrix of carboxylated trehalose-modified PVA. When the coating film is subjected to external stretching, the network structure of the bamboo fiber can disperse stress, absorb external force, and enhance the cohesive strength of the coating film. The molecular chain of carboxylated trehalose-modified PVA contains hydroxyl and carboxyl groups, especially the branched hydroxyl groups of trehalose. The terminal amino hyperbranched polymer grafted onto the surface of the aminated modified bamboo fiber carries a large number of amino groups, which can bond with the carboxyl groups in the carboxylated trehalose-modified PVA molecules, greatly improving the adhesion and weather resistance of the coating film. In addition, mineral pigments are inorganic powders, which are prone to agglomeration, resulting in uneven color of the paint film. The polar functional groups of carboxylated trehalose-modified PVA can be adsorbed on the surface of pigment particles to form a steric hindrance layer, preventing pigment particles from agglomerating.

[0065] Other embodiments of this disclosure will readily occur to those skilled in the art upon consideration of the specification and practice of the disclosure herein. This disclosure is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not disclosed herein.

Claims

1. A coating composition for use on the red walls of ancient buildings, characterized in that, The coating composition comprises the following components in parts by weight: 18-25 parts by weight of mineral pigment, 0.5-2 parts by weight of fiber material, 0.2-0.5 parts by weight of montmorillonite, 0.2-0.5 parts by weight of diatomaceous earth, and 65-85 parts by weight of water.

2. The coating composition for the red wall surface of ancient buildings according to claim 1, characterized in that, The mineral pigments include cinnabar, ochre, and carmine; the mass ratio of cinnabar, ochre, and carmine is selected from (3~5):(1~3):(0.5~1.5).

3. The coating composition for the red wall surface of ancient buildings according to claim 1, characterized in that, The fiber material is selected from modified or unmodified lignin fiber, modified or unmodified alkali-free chopped glass fiber, modified or unmodified bamboo fiber, or modified or unmodified hemp fiber.

4. The coating composition for the red wall surface of ancient buildings according to claim 1, characterized in that, The fiber material is amination-modified bamboo fiber; the amination-modified bamboo fiber is prepared through the following steps: Step 1-a: Provide bamboo fiber; pre-treat the bamboo fiber; Step 2-a: Preparation of terminal amino-branched polymers; Step 3-a: The pretreated bamboo fiber obtained in step 1-a is mixed with the terminal amino-branched polymer obtained in step 1-a, and after reaction, the amino-modified bamboo fiber is obtained.

5. The coating composition for the red wall surface of ancient buildings according to claim 4, characterized in that, The aminated bamboo fiber was prepared through the following steps: Step 1-a: Provide bamboo fiber. Wash, dry, crush, and pass the bamboo fiber through a 100-150 mesh sieve to obtain sieved bamboo fiber. Add the sieved bamboo fiber to a KOH solution and shake for 1-2 hours. Then remove the fiber, wash and dry it, and add it to a succinic acid solution and shake for 1-2 hours. Then remove the fiber, wash and dry it to obtain the pretreated bamboo fiber. Step 2-a: Add diethylenetriamine to the reaction vessel, control the temperature of the reaction system at 5~10℃, add water to dilute the diethylenetriamine; then add N,N-methylenebisacrylamide, and after it is completely dissolved, raise the temperature of the reaction system to 70~80℃ and react for 20~28h; after the reaction is completed, cool down and separate to obtain the terminal amino branched polymer. Step 3-a: Add the pretreated bamboo fiber to the reaction vessel, add water and glutaraldehyde solution, and stir at room temperature for 1-2 hours; then add the terminal amino-branched polymer, heat to 60-70°C, and stir for 6-12 hours; after the reaction is completed, filter, wash and dry to obtain the amino-modified bamboo fiber.

6. The coating composition for the red wall surface of ancient buildings according to claim 1, characterized in that, The natural dispersant coating composition further includes the following components in parts by weight: 5 to 10 parts by weight of polyvinyl alcohol or polyvinyl alcohol derivatives.

7. The coating composition for the red wall surface of ancient buildings according to claim 1, characterized in that, The polyvinyl alcohol derivative is selected from polyvinyl alcohol modified with carboxylated trehalose; the polyvinyl alcohol modified with carboxylated trehalose is prepared by the following steps: Step 1-b: Provide trehalose, and modify the trehalose by carboxylation to obtain carboxylated trehalose; the carboxylated trehalose has the following structural formula: Step 2-b: Add the carboxylated trehalose to water, and then stir under ice-water bath conditions. During the stirring process, add 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 4-dimethylaminopyridine. After the addition is complete, continue stirring for 1 to 1.5 hours to obtain a mixed solution. Step 3-b: Provide polyvinyl alcohol, dissolve the polyvinyl alcohol in hot water, and then cool to room temperature to obtain an aqueous solution of polyvinyl alcohol; add the aqueous solution of polyvinyl alcohol dropwise to the mixed solution obtained in step 2-b, then seal and let stand for 2-5 days. After the reaction is complete, dialyze and freeze-dry the reaction solution to obtain the carboxylated trehalose-modified polyvinyl alcohol; the reaction steps are as follows: 。 8. The coating composition for the red wall surface of ancient buildings according to claim 7, characterized in that, Step 1-b includes: Step 1-c: Provide trehalose; add the trehalose to anhydrous DMF, then place the reaction system under a nitrogen atmosphere, heat to 75~85℃ and keep stirring to obtain a mixed solution; Step 2-c: Dissolve succinic anhydride in anhydrous DMF, then add it dropwise to the mixed solution obtained in step 1-c, and then add triethylamine. Keep the reaction at the temperature for 10-20 hours. Step 3-c: After the reaction is complete, DMF is first distilled off under reduced pressure; then, a mixed precipitant containing diethyl ether and acetone is used for precipitation to obtain the carboxylated trehalose; the reaction steps are as follows: 。 9. The coating composition for the red wall surface of ancient buildings according to claim 1, characterized in that, The coating composition also includes other additives selected from one or more of binders, solubilizers, dispersants, thickeners, film-forming agents, and fillers, and does not contain titanium dioxide or carbon black.

10. The application of the coating composition for the red wall surface of ancient buildings according to any one of claims 1 to 9 in the restoration of the red wall surface of ancient buildings.

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