Plant-based inorganic coating and preparation method thereof

Abstract

The invention discloses a plant-based inorganic coating and a preparation method thereof, and belongs to the technical field of coatings. The coating comprises the following raw materials in parts by weight: 20-30 parts of potassium silicate; 40 parts of silica sol and 10 parts of silica sol; 20 parts of the raw materials and 10 parts of a plant extract; 20 parts of the raw materials and 10 parts of the modified corncob charcoal; 25 parts of a pigment; 10 parts of an inorganic filler; 30 parts of an auxiliary agent; 5 parts of a stabilizer; 3 parts of water and 10 parts of water; and 20 parts. According to the invention, specific plant extract and zinc are introduced; and the cerium co-modified charcoal and the inorganic base material generate a synergistic effect, so that the flexibility and the cracking resistance of the coating are remarkably improved on the basis of retaining the excellent fireproof, durable and environment-friendly properties of the traditional inorganic coating, and the coating is endowed with efficient and lasting dual functions of formaldehyde purification, bacteria resistance and mildew resistance. The product disclosed by the invention has the characteristics of extremely low VOC content and excellent comprehensive performance, and is suitable for the field of building interior wall decoration with high requirements on indoor environment health and sustainability.

Description

TECHNICAL FIELD

[0001] The present application relates to a plant-based inorganic coating and a preparation method thereof, and belongs to the technical field of coatings. BACKGROUND

[0002] With the rapid development of the world economy and the continuous improvement of people's living standards, the pollution and toxicity of coatings have attracted increasing attention, and protecting the environment and saving resources have become a topic of common concern. Therefore, countries around the world have formulated regulations to promote the transformation of the traditional coating industry to green and environmentally friendly coatings. It is imperative to vigorously develop environmentally friendly interior wall coatings, which is necessary for people's physical health, social economy, energy saving and sustainable development.

[0003] Traditional coatings generally refer to a type of coating that uses organic synthetic resins as the main film-forming material, uses organic solvents or water as the dispersion medium, and contains a large amount of chemical synthetic additives. With the tightening of environmental regulations and the improvement of people's health awareness, traditional coatings, especially high-VOC solvent-based coatings, are gradually being replaced by more advanced and greener products.

[0004] Inorganic coatings are a type of material that mainly uses inorganic materials as the film-forming material. Due to its excellent environmental protection (low VOC), durability, fire resistance (A-level), and mildew resistance and antibacterial properties, it has been widely used in the decoration of interior and exterior walls. The film-forming material is mainly potassium silicate, silica sol, and other inorganic alkali silicates. However, traditional inorganic coatings have the following shortcomings: 1) poor flexibility: the coating is hard but lacks elasticity, and when the base layer cracks or expands and contracts, it is easy to crack. 2) Poor workability: the brushing feel may be a bit rough, and the leveling property is not as good as high-end organic latex paint, requiring high construction technology. 3) Insufficient sustainability of raw materials: although it is environmentally friendly, its main raw materials still come from mining and chemical production, and there is still room for improvement in terms of "green and renewable". With the increasing demand for indoor environmental health and sustainable development, developing a new type of inorganic coating with more balanced performance and more environmentally friendly raw materials has become a technical problem to be solved. SUMMARY

[0005] The purpose of the present application is to overcome the shortcomings of the prior art and provide a plant-based inorganic coating and a preparation method thereof. The coating retains the excellent performance of inorganic coatings, effectively improves the flexibility and workability of the coating by introducing specific plant-based ingredients, and further improves the environmental protection and biobased content of the product.

[0006] A plant-based inorganic coating, which comprises the following raw materials in parts by weight: potassium silicate 20-40 parts, silica sol 10-20 parts, plant extract 10-20 parts, modified corn cob biochar 10-25 parts, pigment 5-10 parts, inorganic filler 15-30 parts, auxiliary agent 1-5 parts, stabilizer 1-3 parts, and water 10-20 parts.

[0007] Preferably, the plant extract is prepared by the following method: weighing pomegranate peel powder, adding a phosphate buffer solution with pH 7.5 according to the solid-liquid ratio, mixing uniformly, adding a compound enzyme, and enzymolysis at 40-45°C for 4h. After the reaction is completed, the enzyme is immediately inactivated in boiling water for 10 min, and the filtrate is vacuum freeze-dried into powder.

[0008] Preferably, the solid-liquid ratio of the pomegranate peel powder and the phosphate buffer solution is 1g:20mL.

[0009] Preferably, the amount of the compound enzyme is 2-3% of the mass of the pomegranate peel powder.

[0010] Preferably, the mass ratio of cellulase, pectinase, endoglucanase, and bromelain in the compound enzyme is (1-2):1:(0.5-1):(0.6-0.8).

[0011] Preferably, the modified corn cob biochar is prepared by the following method: (1) Washing, drying, cooling, and crushing the corn cob to obtain corn cob particles, uniformly mixing the corn cob particles with KHCO3 at a mass ratio of 1:1, then transferring into a muffle furnace to heat to 600°C in an oxygen-free environment, keeping the temperature for 2h, grinding the obtained carbonization product, removing ash, repeatedly washing with water until neutral, and drying at 80°C to obtain the corn cob biochar; (2) Immersing the corn cob biochar obtained in step (1) in a mixed solution containing zinc nitrate and cerium ammonium nitrate according to a solid-liquid ratio, uniformly stirring and slowly adjusting the pH value of the solution to 9.0-10.0 with 0.1 mol / L NaOH solution, stirring for 2h, after the reaction is completed, ultrasonic treatment for 30 min, then placing in an oven for drying, finally transferring into a muffle furnace, heating to 450-550°C in an oxygen-free environment, calcining for 2h, washing the calcined product with water until neutral, and drying and grinding into powder.

[0012] Preferably, the solid-liquid ratio is 1g:30mL; the concentration of zinc nitrate in the mixed solution is 0.2mol / L, and the concentration of cerium ammonium nitrate is 0.1mol / L.

[0013] Preferably, the auxiliary agent is composed of defoaming agent 0.5-1 part, thickening agent 3-5 parts, and wetting agent 1-2 parts.

[0014] Preferably, the inorganic filler is one or more of titanium white, heavy calcium, talcum powder, and kaolin.

[0015] Preferably, the stabilizer is alkyl phenol polyoxyethylene ether and triethanolamine in a mass ratio of 1:2.

[0016] The present application also provides a preparation method of the plant-based inorganic coating as described above, comprising the following steps: S1: under stirring at 300-400 rpm, potassium silicate, silica sol, and water are added into a reaction kettle, mixed uniformly to form an inorganic base; S2: while stirring, pre-prepared plant extract powder and stabilizer are added into the inorganic base, the stirring speed is slowly increased to 600 rpm, and the stirring is continued for 20 min until the system is uniform; S3: under stirring at 400-500 rpm, modified corncob biochar and inorganic filler are slowly added, after the addition is completed, the stirring speed is increased to 800-1000 rpm, high-speed dispersion is performed for 30 min, then the stirring speed is reduced to 500 rpm, and then wetting agent, defoaming agent, thickening agent, and pigment are sequentially added, after each additive is added, the stirring is performed for 5 min, then the next additive is added, after all the additives are added, the stirring is continued for 15 min to make the coating system uniform, then the system is filtered through a 200-mesh screen, and a plant-based inorganic coating product is obtained.

[0017] The pigment used in the present application is selected from one of chromium green, iron oxide red, iron oxide black, cobalt blue, and cobalt green; The thickening agent is selected from at least one of hydroxymethyl cellulose, hydroxyethyl cellulose, and guar gum; The defoaming agent is a silicone-based defoaming agent, and the wetting agent is a polyoxyethylene alkyl ether.

[0018] The biochar itself has irregular lamellar porous structure, the irregular nanoparticles are staggered in the paint to form a microscopic reinforcing network, which can effectively hinder the penetration of cracks, so that the cracks need to bypass the hard particles or deflect in the expansion process, thereby improving the fracture toughness and strength of the coating; and the modified corn cob biochar used in the application is treated by zinc-cerium modification, a large number of metal oxide active sites are introduced on the surface of the biochar, the active sites are chemically bonded (such as Si-O-Zn or Si-O-Ce bond) with the silicon hydroxyl in potassium silicate and silica sol, the strong chemical bonding greatly improves the interfacial bonding force between the biochar and the inorganic matrix, avoids the peeling and defects caused by weak interface, and forms a flexible organic-inorganic hybrid structure in the rigid inorganic silicate network, so that the coating has better elasticity and ductility while maintaining hardness, and overcomes the weakness of poor flexibility of traditional inorganic coatings. In addition, the modified corn cob biochar used in the application has rich microporous structure and large specific surface area, and can efficiently adsorb harmful gases such as formaldehyde, and the ZnO / CeO2 nanoparticles on the surface of the modified corn cob biochar can catalytically degrade formaldehyde under light, so as to effectively purify indoor air and create a healthier and safer living environment for people, and is especially suitable for newly decorated houses and public places.

[0019] The plant extract used in the application is rich in tannin (polyphenol) and plant polysaccharide and other natural high molecular compounds, and a large number of active functional groups such as phenolic hydroxyl and carboxyl are contained on the molecular chain, the long-chain macromolecules are inserted in the rigid inorganic siloxane network, and play a good absorption and dispersion stress role through hydrogen bonding and physical action, which can significantly improve the flexibility and impact resistance of the coating film, and the active functional groups can also interact with the silicon hydroxyl in the inorganic binder (potassium silicate, silica sol), and can also be combined with the functional groups on the surface of the biochar, thereby playing a bridge role between the inorganic phase and the organic phase / carbon material, improving the interfacial compatibility and preventing phase separation. In addition, pomegranate peel polyphenol is a natural broad-spectrum antibacterial agent, which provides the first biological defense barrier for the coating, chemically inhibits the germination of mold spores and the reproduction of bacteria, and the antibacterial effect is complementary to the physical antibacterial effect, thereby enhancing the mildew-resistant and antibacterial effect of the coating.

[0020] The beneficial effects of the application are: (1) The plant extract and modified corn cob biochar introduced in the application are renewable resources, which further improves the environmental protection and bio-based content of the product, reduces the dependence on traditional chemical raw materials, and is more in line with the green and environmentally friendly development concept.

[0021] (2) The addition of the plant extract and the modified corncob biochar makes the coating maintain the durability of inorganic paint while increasing flexibility, better adapting to the subtle deformation of the base layer, reducing the generation of cracks, and prolonging the service life of the paint; meanwhile, the construction performance of the paint is improved, the brushing feel is smoother, the leveling property is better, the construction difficulty is reduced, and the construction efficiency is improved.

[0022] (3) The plant extract contains various natural antibacterial components and has good antibacterial property; the modified corncob biochar is rich in microporous structures and various active groups on the surface and can adsorb and inhibit the growth of bacteria, and the synergistic effect of the two makes the paint have stronger antibacterial and antiseptic properties, can effectively inhibit the breeding of mold and bacteria, reduce the problems such as mildewing and discoloration of the coating caused by microbial growth, maintain the cleanliness and beauty of the wall surface, and is especially suitable for use in humid environments.

[0023] (4) The zinc-cerium modified biochar prepared in the application adsorbs formaldehyde, and the metal oxide nanoparticles on the surface catalytically degrade formaldehyde under light; the phenolic hydroxyl groups and other groups of pomegranate peel polyphenols can act as nucleophilic reagents to react with formaldehyde, and a part of formaldehyde molecules is converted into stable compounds by chemical fixation, as a complementary path for photocatalytic degradation; the synergistic effect of the two forms a triple purification network of fixation-adsorption-degradation, improves the removal efficiency and reliability of formaldehyde under no light or weak light conditions, and effectively purifies indoor air. DETAILED DESCRIPTION

[0024] The technical solutions of the application are further described below in combination with specific embodiments, but are not limited thereto. The modulus of potassium silicate used in the application is 2.5-4.0, which is purchased from Guangzhou Fur Chemical Co., Ltd.; the silica sol is LS-30 purchased from Zhejiang Yuda Chemical Co., Ltd.

[0025] Example 1 A plant-based inorganic paint, which comprises the following raw materials in parts by weight: 20 parts of potassium silicate, 10 parts of silica sol, 10 parts of plant extract, 10 parts of modified corncob biochar, 5 parts of pigment, 15 parts of inorganic filler, 1 part of auxiliary agent, 1 part of stabilizer, and 10 parts of water.

[0026] The plant extract is prepared by the following method: pomegranate peel powder is weighed, pH 7.5 phosphate buffer solution is added at a ratio of 1g:20mL of liquid, and mixed uniformly, a composite enzyme is added for enzymolysis at 40-45℃ for 4h, after the reaction is completed, the enzyme is immediately inactivated in boiling water for 10 min, and the filtrate is vacuum freeze-dried into powder.

[0027] The amount of the composite enzyme is 2% of the mass of the pomegranate peel powder.

[0028] The mass ratio of cellulase, pectinase, endoglucanase and bromelain in the complex enzyme is 1:1:0.5:0.6.

[0029] The modified corncob biochar is prepared by the following method: (1) The corncob is washed, dried, cooled and crushed to obtain corncob particles, which are mixed with KHCO3 at a mass ratio of 1:1, then transferred into a muffle furnace and heated to 600 DEG C in an oxygen-free environment for 2h, the obtained carbonized product is ground, sieved, ash removed, washed repeatedly with water until neutral, and dried at 80 DEG C to obtain corncob biochar; (2) The corncob biochar obtained in step (1) is immersed in a mixed solution containing zinc nitrate and cerium ammonium nitrate at a solid-liquid ratio of 1g:30mL, stirred uniformly, and the pH value of the solution is slowly adjusted to 9.0-10.0 with 0.1 mol / L NaOH solution, stirred for 2h, after the reaction is completed, the mixture is ultrasonically treated for 30 min, then placed in an oven and dried, finally transferred into a muffle furnace, heated to 450-550 DEG C in an oxygen-free environment, calcined for 2h, cooled, washed the calcined product with water until neutral, and dried and ground into powder again.

[0030] The concentration of zinc nitrate in the mixed solution is 0.2 mol / L, and the concentration of cerium ammonium nitrate is 0.1 mol / L.

[0031] The auxiliary agent is composed of 0.5 parts of defoaming agent, 3 parts of thickening agent and 1 part of wetting agent.

[0032] The inorganic filler is composed of 5 parts of titanium white, 5 parts of heavy calcium and 5 parts of talc.

[0033] The pigment used in the application is selected from chromium green; the thickening agent is hydroxymethyl cellulose; the defoaming agent is an organic silicon defoaming agent; and the wetting agent is polyoxyethylene alkyl ether.

[0034] The stabilizer is composed of alkyl phenol polyoxyethylene ether and triethanolamine at a mass ratio of 1:2.

[0035] The application also provides a preparation method of the plant-based inorganic coating. S1: potassium silicate, silica sol and water are added into a reaction kettle under stirring at 300-400 rpm, mixed uniformly to form an inorganic base material; S2: the stirring is kept, the pre-prepared plant extract powder and the stabilizer are added into the inorganic base material, the rotating speed is slowly increased to 600 rpm, and the stirring is continuously carried out for 20 min until the system is uniform; S3: Under the stirring speed of 400-500 rpm, the modified corncob biochar and inorganic fillers are slowly added, after the addition is completed, the speed is increased to 800-1000 rpm, and high-speed dispersion is carried out for 30 min, then the speed is reduced to 500 rpm, and then the wetting agent, defoaming agent, thickening agent and pigment are sequentially added, each additive is stirred for 5 min after being added, and then the next additive is added, after all the additives are added, the coating system is continuously stirred for 15 min to reach a uniform state, and then the product is filtered through a 200 mesh screen to obtain a plant-based inorganic coating product.

[0036] Example 2 A plant-based inorganic coating, comprising the following raw materials by weight: potassium silicate 30 parts, silica sol 15 parts, plant extract 15 parts, modified corncob biochar 20 parts, pigment 8 parts, inorganic filler 20 parts, additive 3 parts, stabilizer 2 parts, and water 15 parts.

[0037] The plant extract is prepared by the following method: pomegranate peel powder is weighed, mixed with a pH 7.5 phosphate buffer solution according to a ratio of 1g:20mL, and then a composite enzyme is added for enzymatic hydrolysis at 40-45℃ for 4h, after the reaction is completed, the enzyme is immediately inactivated in boiling water for 10 min, and then the filtrate is vacuum freeze-dried into powder.

[0038] The amount of the composite enzyme is 3% of the mass of the pomegranate peel powder.

[0039] The mass ratio of cellulase, pectinase, endoglucanase and bromelain in the composite enzyme is 2:1:1:0.8.

[0040] The modified corncob biochar is prepared by the following method: (1) The corncob is washed, dried, cooled and crushed to obtain corncob particles, which are then mixed with KHCO3 at a mass ratio of 1:1, and then transferred into a muffle furnace in an oxygen-free environment and heated to 600℃, and kept for 2h, then the obtained carbonized product is ground, sieved, ash removed, and repeatedly washed with water until neutral, and then dried at 80℃ to obtain corncob biochar; (2) The corncob biochar obtained in step (1) is immersed in a mixed solution containing zinc nitrate and cerium ammonium nitrate at a solid-liquid ratio of 1g:30mL, stirred uniformly, and then the pH value of the solution is slowly adjusted to 9.0-10.0 with 0.1 mol / L NaOH solution, stirred for 2h, after the reaction is completed, the mixture is ultrasonically treated for 30 min, then placed in an oven for drying, and finally transferred into a muffle furnace in an oxygen-free environment and heated to 450-550℃, and calcined for 2h, then the calcined product is washed with water until neutral, and then dried and ground into powder.

[0041] The concentration of zinc nitrate in the mixed solution is 0.2 mol / L, and the concentration of cerium ammonium nitrate is 0.1 mol / L.

[0042] The auxiliary agent is composed of 1 part of defoaming agent, 5 parts of thickening agent and 2 parts of wetting agent.

[0043] The inorganic filler is composed of 10 parts of titanium white, 5 parts of heavy calcium and 5 parts of talcum powder.

[0044] The pigment used in the application is iron oxide red; the thickening agent is hydroxyethyl cellulose; the defoaming agent is an organic silicon defoaming agent; and the wetting agent is polyoxyethylene alkyl ether.

[0045] The stabilizer is composed of alkyl phenol polyoxyethylene ether and triethanolamine in a mass ratio of 1:2.

[0046] The application also provides a preparation method of the plant-based inorganic coating. S1: under stirring at 300-400 rpm, potassium silicate, silica sol and water are added into a reaction kettle, mixed uniformly to form an inorganic base; S2: while stirring, pre-prepared plant extract powder and stabilizer are added into the inorganic base, the stirring speed is slowly increased to 600 rpm, and the stirring is continuously conducted for 20 min until the system is uniform; S3: under stirring at 400-500 rpm, modified corncob biochar and inorganic filler are slowly added, after the addition is completed, the stirring speed is increased to 800-1000 rpm, high-speed dispersion is conducted for 30 min, then the stirring speed is reduced to 500 rpm, and then wetting agent, defoaming agent, thickening agent and pigment are sequentially added, after each auxiliary agent is added, stirring is conducted for 5 min, then the next one is added, after all the auxiliary agents are added, stirring is continuously conducted for 15 min, so that the coating system reaches a uniform state, then the product is filtered through a 200-mesh screen, and a plant-based inorganic coating product is obtained.

[0047] Example 3 A plant-based inorganic coating, which comprises the following raw materials in parts by weight: 40 parts of potassium silicate, 20 parts of silica sol, 20 parts of plant extract, 25 parts of modified corncob biochar, 10 parts of pigment, 30 parts of inorganic filler, 5 parts of auxiliary agent, 3 parts of stabilizer and 20 parts of water.

[0048] The plant extract is prepared by the following method: pomegranate peel powder is weighed, mixed with pH 7.5 phosphate buffer solution at a ratio of 1g:20mL, and then complex enzymes are added for enzymolysis at 40-45 DEG C for 4h, after the reaction is completed, the enzymes are immediately inactivated in boiling water for 10 min, and then the filtrate is vacuum freeze-dried into powder.

[0049] The amount of the complex enzyme is 2% of the mass of the pomegranate peel powder.

[0050] The mass ratio of cellulase, pectinase, endoglucanase and bromelain in the complex enzyme is 1.5:1:0.6:0.7.

[0051] The modified corncob biochar is prepared by the following method: (1) The corncob is washed, dried, cooled and crushed to obtain corncob particles, which are uniformly mixed with KHCO3 at a mass ratio of 1:1, and then transferred into a muffle furnace to be heated to 600 DEG C in an oxygen-free environment, and kept for 2 hours, the obtained carbonized product is ground, sieved, ash removed, washed repeatedly with water until neutral, and dried at 80 DEG C to obtain corncob biochar; (2) The corncob biochar obtained in step (1) is immersed in a mixed solution containing zinc nitrate and cerium ammonium nitrate at a solid-liquid ratio of 1g:30mL, stirred uniformly, and the pH value of the solution is slowly adjusted to 9.0-10.0 with 0.1 mol / L NaOH solution, stirred for 2 hours, after the reaction is completed, the mixture is ultrasonically treated for 30 minutes, then placed in an oven for drying, finally transferred into a muffle furnace, heated to 450-550 DEG C in an oxygen-free environment, calcined for 2 hours, cooled, washed the calcined product with water until neutral, and dried and ground into powder again.

[0052] The concentration of zinc nitrate in the mixed solution is 0.2 mol / L, and the concentration of cerium ammonium nitrate is 0.1 mol / L.

[0053] The auxiliary agent is composed of 0.6 parts of defoaming agent, 4 parts of thickening agent and 1.5 parts of wetting agent.

[0054] The inorganic filler is composed of 10 parts of titanium white, 5 parts of heavy calcium, 5 parts of kaolin and 10 parts of talc powder.

[0055] The pigment used in the application is iron oxide black; the thickening agent is guar gum; the defoaming agent is an organic silicon defoaming agent; and the wetting agent is polyoxyethylene alkyl ether.

[0056] The stabilizer is composed of alkyl phenol polyoxyethylene ether and triethanolamine at a mass ratio of 1:2.

[0057] The application also provides a preparation method of the plant-based inorganic coating. S1: potassium silicate, silica sol and water are added into a reaction kettle under stirring at 300-400 rpm, uniformly mixed to form an inorganic base material; S2: the pre-prepared plant extract powder and stabilizer are added into the inorganic base material under stirring, the rotating speed is slowly increased to 600 rpm, and the stirring is continuously carried out for 20 minutes until the system is uniform; S3: At the stirring speed of 400-500 rpm, the modified corncob biochar and inorganic fillers were slowly added, after the addition was completed, the speed was increased to 800-1000 rpm, and high-speed dispersion was carried out for 30 min, then the speed was reduced to 500 rpm, and then the wetting agent, defoaming agent, thickening agent and pigment were sequentially added, each additive was stirred for 5 min, then the next additive was added, after all the additives were added, the stirring was continued for 15 min to make the coating system uniform, then it was filtered through a 200 mesh screen, and a plant-based inorganic coating product was obtained.

[0058] Comparative Example 1 A plant-based inorganic coating, the raw material composition of which was basically the same as that of Example 1, except that it did not contain plant extracts.

[0059] Comparative Example 2 A plant-based inorganic coating, the raw material composition of which was basically the same as that of Example 1, except that it did not contain modified corncob biochar.

[0060] Comparative Example 3 A plant-based inorganic coating, the raw material composition of which was basically the same as that of Example 1, except that ordinary corncob biochar was used instead of modified corncob biochar.

[0061] The ordinary corncob biochar was prepared by the following method: corn cobs were washed, dried, cooled and ground to obtain corncob particles, the corncob particles were mixed with KHCO3 at a mass ratio of 1:1, then transferred into a muffle furnace in an oxygen-free environment, heated to 600°C, and kept for 2 h, the obtained carbonized product was ground and sieved, ash content was removed, then washed repeatedly with water until neutral, and dried at 80°C to obtain corncob biochar.

[0062] Comparative Example 4 A plant-based inorganic coating, the raw material composition of which was basically the same as that of Example 1, except that the preparation method of the modified corncob biochar was different. The modified corncob biochar used in this comparative example was prepared by the following method: (1) Corn cobs were washed, dried, cooled and ground to obtain corncob particles, the corncob particles were mixed with KHCO3 at a mass ratio of 1:1, then transferred into a muffle furnace in an oxygen-free environment, heated to 600°C, and kept for 2 h, the obtained carbonized product was ground and sieved, ash content was removed, then washed repeatedly with water until neutral, and dried at 80°C to obtain corncob biochar; (2) The corn cob biochar obtained in step (1) is immersed in a 0.2 mol / L zinc nitrate solution at a solid-liquid ratio of 1 g:30 mL, stirred uniformly, and the pH value of the solution is slowly adjusted to 9.0-10.0 with a 0.1 mol / L NaOH solution, stirred for 2 h, after the reaction is completed, the mixture is ultrasonically treated for 30 min, then placed in an oven for drying, finally transferred into a muffle furnace, heated to 450-550°C in an oxygen-free environment, calcined for 2 h, after cooling, the calcined product is washed with water until neutral, dried again, and ground into powder.

[0063] Comparative Example 5 A plant-based inorganic coating, the raw material composition of which is basically the same as that of Example 1, the only difference being that the preparation method of the modified corn cob biochar is different. The modified corn cob biochar used in this comparative example is prepared by the following method: (1) The corn cob is washed, dried, cooled, and ground to obtain corn cob particles, the corn cob particles are mixed with KHCO3 at a mass ratio of 1:1, then transferred into a muffle furnace, heated to 600°C in an oxygen-free environment, and kept for 2 h, the obtained carbonized product is ground, sieved, ash removed, and repeatedly washed with water until neutral, dried at 80°C to obtain corn cob biochar; (2) The corn cob biochar obtained in step (1) is immersed in a 0.2 mol / L zinc nitrate solution at a solid-liquid ratio of 1 g:30 mL, stirred uniformly, and the pH value of the solution is slowly adjusted to 9.0-10.0 with a 0.1 mol / L NaOH solution, stirred for 2 h, after the reaction is completed, the mixture is ultrasonically treated for 30 min, then placed in an oven for drying, finally transferred into a muffle furnace, heated to 450-550°C in an oxygen-free environment, calcined for 2 h, after cooling, the calcined product is washed with water until neutral, dried again, and ground into powder.

[0064] Performance Test All the samples prepared in Examples 1-3 and Comparative Examples 1-5 above are uniformly brushed on standard cement asbestos boards, and after they are completely solidified, the following tests are carried out. The results are the average of three tests, as shown in the table below.

[0065] Table 1 Test results of basic physical and chemical properties of coatings From the above data, all embodiments of the present application exhibit excellent adhesion (0 level), indicating that the introduction of plant extracts does not weaken the bonding of the coating and the substrate, but may be enhanced due to its bridging effect. The hardness of the embodiments remains at a high level of 4H-5H, although slightly lower than Comparative Example 1 without plant flexible components, but significantly higher than Comparative Example 2 without biochar enhancement, reflecting the synergistic balance of plant extracts providing flexibility and biochar providing enhancement. The scrub resistance of Examples 1-3 of the present application far exceeds Comparative Examples 1-5, proving that the modified corn cob biochar and plant extracts work together to form a more wear-resistant and denser coating structure. And the VOC content of the product obtained by the present application is less than 2.5 g / L, which meets the green coating standard, and is better than Comparative Examples 1-5.

[0066] Table 2 Coating flexibility and functionality test results Note: The construction performance is evaluated by brushing hand feel score (1-5 points, 5 points for the best), leveling (observing the flatness of the coating surface after 24 hours, no brush marks, no edge shrinkage is qualified).

[0067] From the data in Table 2 above, the flexibility of Examples 1-3 of the present application all reach 1 mm level, and the construction hand feel score is close to 5 points, which is significantly better than Comparative Examples 1-5. It is proved that the synergistic effect of plant extracts and zinc-cerium modified corn cob biochar effectively improves the rigidity defect of inorganic coatings and improves the smoothness and leveling of brushing. The antibacterial rate of Examples 1-3 on E. coli is as high as 99.2% or more, and the mildew resistance level is 0 level (no long mold), showing comprehensive and efficient biological inhibition performance. The antibacterial rate of Comparative Example 1 is significantly reduced, and the mildew resistance level is reduced to 1 level. This fully proves that natural antibacterial ingredients such as pomegranate peel polyphenols provide an indispensable and active chemical antibacterial barrier, which is the first key line of defense against mold growth (mildew resistance). The antibacterial rates of Comparative Examples 2-5 are 80.1%-91.5%, and they can resist mildew (0 level), indicating that the micropore adsorption and physical inhibition of biochar are effective. However, its antibacterial rate is still generally less than 99%, which highlights the synergistic effect of natural chemical antibacterial ingredients provided by plant extracts and physical antibacterial of biochar, which can achieve almost complete antibacterial effect (>99%), forming a more perfect defense system.

[0068] The formaldehyde purification efficiency of the embodiments 1-3 of the present application is significantly higher than that of the comparative examples 1-5. This result shows the effectiveness of the triple purification network of "adsorption-photocatalysis-chemical fixation" and the synergistic effect of its components. The purification efficiency of comparative example 1 and comparative example 2 is the lowest, which shows that the plant extract and the modified biochar are two indispensable components of the complete purification system, and the absence of any component will cause a significant decrease in performance. The efficiency of comparative example 3 is significantly lower than that of the embodiments, which shows that the simple physical adsorption has limited effect, and the photocatalytic active component introduced by zinc-cerium co-modification is the key to improve the purification efficiency. The purification efficiency of comparative example 4 and comparative example 5 is also low, which proves that the co-modification of zinc (ZnO) and cerium (CeO2) has a significant synergistic catalytic effect, and the two components promote each other in the energy band structure, producing stronger photocatalytic activity than single modification, and achieving better removal effect of formaldehyde. The formaldehyde purification effect of embodiments 1-3 is durable, and the durability reaches more than 80%, which is much higher than that of comparative examples 1-5. This also shows the effectiveness of the triple purification network in improving the durability of formaldehyde removal.

[0069] It should be noted that the above embodiments are only part of the preferred modes of implementing the present application, not all. Obviously, based on the above embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor should belong to the scope of protection of the present application.

Claims

1. A plant-based inorganic coating material, characterized by, It comprises the following raw materials by weight: potassium silicate 20-40 parts, silica sol 10-20 parts, plant extract 10-20 parts, modified corncob biochar 10-25 parts, pigment 5-10 parts, inorganic filler 15-30 parts, auxiliary agent 1-5 parts, stabilizer 1-3 parts, and water 10-20 parts.

2. The plant-based inorganic coating of claim 1, wherein, The plant extract is prepared by the following method: pomegranate peel powder is weighed, mixed with pH 7.5 phosphate buffer according to the solid-liquid ratio, and then complex enzymes are added for enzymatic hydrolysis at 40-45°C for 4 hours. After the reaction is completed, the enzymes are immediately inactivated in boiling water for 10 minutes, and then the filtrate is vacuum freeze-dried into powder.

3. The plant-based inorganic coating of claim 2, wherein, The solid-liquid ratio of the pomegranate peel powder to the phosphate buffer is 1g:20mL.

4. The plant-based inorganic coating of claim 2, wherein, The amount of the complex enzyme is 2-3% of the mass of the pomegranate peel powder.

5. The plant-based inorganic coating of claim 4, wherein, The mass ratio of cellulase, pectinase, endoglucanase, and bromelain in the complex enzyme is (1-2):1:(0.5-1):(0.6-0.8).

6. The plant-based inorganic coating of claim 1, wherein, The modified corncob biochar is prepared by the following method: (1) The corncob is washed, dried, cooled, and crushed to obtain corncob particles. The corncob particles are mixed with KHCO3 at a mass ratio of 1:1, and then transferred into a muffle furnace to heat to 600°C in an oxygen-free environment for 2 hours. The obtained carbonized product is ground, sieved, and treated to remove ash. Then, the product is repeatedly washed with water until it is neutral. Finally, the product is dried at 80°C to obtain the corncob biochar. (2) The corncob biochar obtained in step (1) is immersed in a mixed solution containing zinc nitrate and cerium ammonium nitrate according to a solid-liquid ratio. The solution is stirred uniformly and the pH value is slowly adjusted to 9.0-10.0 with 0.1 mol / L NaOH solution. The mixture is stirred for 2 hours, then treated with ultrasonic for 30 minutes, and then dried in an oven. Finally, the mixture is calcined in a muffle furnace at 450-550°C in an oxygen-free environment for 2 hours. After cooling, the calcined product is washed with water until it is neutral, and then dried and ground into powder.

7. The plant-based inorganic coating of claim 6, wherein, The solid-liquid ratio is 1g:30mL. The concentration of zinc nitrate in the mixed solution is 0.2 mol / L, and the concentration of cerium ammonium nitrate is 0.1 mol / L. The plant-based inorganic paint according to claim 1, wherein the auxiliary agent is composed of 0.5-1 parts of defoaming agent, 3-5 parts of thickening agent, and 1-2 parts of wetting agent.

8. The plant-based inorganic coating of claim 6, wherein, The inorganic filler is one or more of titanium white, heavy calcium, talc, and kaolin.

9. The plant-based inorganic coating of claim 1, wherein, The stabilizer is composed of alkylphenol polyoxyethylene ether and triethanolamine at a mass ratio of 1:

2.

10. A method of preparing a plant-based inorganic coating according to any one of claims 1-9, characterized in that, The method comprises the following steps: S1: Under stirring at 300-400 rpm, potassium silicate, silica sol, and water are added to a reaction kettle and mixed uniformly to form an inorganic base material; S2: While stirring, the pre-prepared plant extract powder and stabilizer are added to the inorganic base material. The stirring speed is slowly increased to 600 rpm, and the stirring is continued for 20 minutes until the system is uniform. S3: At the stirring speed of 400-500 rpm, slowly add the modified corn cob biochar and inorganic fillers, after the addition is completed, increase the speed to 800-1000 rpm, and disperse at high speed for 30 min, then reduce the speed to 500 rpm, and then add the wetting agent, defoaming agent, thickening agent and pigment in turn, stir for 5 min after adding each additive, and then add the next one, after adding all the additives, continue to stir for 15 min, so that the coating system reaches a uniform state, then filter through a 200 mesh screen, and the plant-based inorganic coating product is obtained.

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