Antibacterial mildew-proof coating and preparation method thereof

Abstract

The invention relates to the technical field of antibacterial and mildewproof coatings, and discloses an antibacterial and mildewproof coating and a preparation method thereof.The preparation method comprises the steps that a hydroxyl ethyoxyl antibacterial silane coupling agent and an aldehyde ethyoxyl antibacterial silane coupling agent are prepared from a natural antibacterial component 4-terpene alcohol existing in tea tree oil as a raw material; based on hydrogen-bond interaction and / or Schiff base reaction, a hydroxyl ethyoxyl antibacterial silane coupling agent and / or an aldehyde ethyoxyl antibacterial silane coupling agent are / is utilized to load a natural antibacterial agent tea tree oil and / or a photocatalyst material TiO2 with an antibacterial function on a diatomite matrix to prepare the load type antibacterial mildew inhibitor. According to the present invention, the load type antibacterial and mildew-proof agent is added to the coating formula as the modification component to prepare the antibacterial and mildew-proof coating, the mildew-proof grade of the coating product is 0 grade, the antibacterial rate is more than 95%, the coating product shows the excellent antibacterial and mildew-proof effects, the comprehensive performance is excellent, and the practical application value is provided.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of antibacterial and mildew-proof coatings, in particular to an antibacterial and mildew-proof coating and a preparation method thereof. BACKGROUND

[0002] Building envelopes often breed microorganisms due to rain, humidity and condensation, and are prone to problems such as dampness and mildew. Painting antibacterial and mildew-proof coatings is one of the important means to improve the mildew problem of buildings. With the improvement of people's quality of life and health consciousness, the demand for coatings with antibacterial and mildew-proof functions is increasing. The research and application of antibacterial and mildew-proof coatings can effectively reduce the breeding of indoor bacteria and mildew, thereby improving indoor air quality, having a positive impact on people's health, and using antibacterial and mildew-proof coatings can reduce the content of indoor chemical substances and harmful gases, and also has a certain contribution to environmental and ecological protection.

[0003] At present, antibacterial and mildew-proof coatings mainly achieve their functions by adding metal ions, organic bactericides and other antibacterial and mildew-proof agents. Among them, the release amount of metal ions gradually decreases over time, leading to a decrease in antibacterial and mildew-proof effect, and the use of metal ions may pollute the water environment; the decomposition products of organic bactericides may be harmful to the human body, and long-term exposure poses a health risk. Therefore, the existing antibacterial and mildew-proof coatings may have problems such as poor antibacterial and mildew-proof effect, poor durability, and insufficient environmental protection.

[0004] Research has found that using natural bioactive substances as antibacterial agents can effectively improve the antibacterial and mildew-proof performance of coatings, and has good environmental protection and safety, meeting the needs of consumers for healthy and environmentally friendly products. In addition, diatomite is a biogenic siliceous sedimentary rock with the advantages of porosity, large specific surface area, large void ratio and low bulk density, and can be used as an excellent antibacterial carrier material to improve antibacterial effect and antibacterial durability.

[0005] Further research has found that the addition of photocatalyst materials (such as TiO2, ZnO, etc.) to antibacterial and mildew-proof coatings can generate strong oxidizing free radicals under light conditions, enhancing the antibacterial and mildew-proof effect, and the photocatalyst materials also have the function of air purification, which can decompose harmful gases (such as formaldehyde, benzene, etc.) in the air, improving indoor air quality. SUMMARY

[0006] The present application uses a self-developed supported antibacterial and mildew-proof agent to prepare an antibacterial and mildew-proof coating by means of supported antibacterial technology and photocatalyst technology. The coating product exhibits excellent antibacterial and mildew-proof effects and can be used in the field of environmentally friendly building materials.

[0007] A preparation method of an antibacterial and mildew-proof coating, comprising the following steps: Step one: using 4-terpenol as raw material, through silicon hydrogen addition reaction and nucleophilic substitution reaction, hydroxyethoxy antibacterial silane coupling agent and aldehyde ethoxy antibacterial silane coupling agent are prepared; Step two: a supported antibacterial and mildew-proof agent is prepared, which is supported antibacterial and mildew-proof agent I or supported antibacterial and mildew-proof agent II; Among them, the supported antibacterial and mildew-proof agent I is first modified by the hydroxyethoxy antibacterial silane coupling agent, and then the tea tree oil is compounded by hydrogen bonding to obtain; The mass ratio of the hydroxyethoxy antibacterial silane coupling agent, diatomite and tea tree oil in the supported antibacterial and mildew-proof agent I is (0.5-2):(3-8):1; The supported antibacterial and mildew-proof agent II is first modified by the hydroxyethoxy antibacterial silane coupling agent and the aldehyde ethoxy antibacterial silane coupling agent, and then the TiO2 nanoparticles modified by the silane coupling agent KH540 are loaded on the surface of the diatomite based on the Schiff base reaction, and the tea tree oil is compounded by hydrogen bonding to obtain; The mass ratio of the hydroxyethoxy antibacterial silane coupling agent, the aldehyde ethoxy antibacterial silane coupling agent, diatomite, TiO2 nanoparticles and tea tree oil in the supported antibacterial and mildew-proof agent II is (0.2-1):(0.2-1):(3-8):(0.1-1):1; Step three: the supported antibacterial and mildew-proof agent is added as a modified component to the paint formula to prepare an antibacterial and mildew-proof paint.

[0008] Preferably, the preparation method of the hydroxyethoxy antibacterial silane coupling agent is: using 4-terpenol as raw material, through the addition reaction of the alkenyl functional group of 4-terpenol and the Si-H functional group of ethoxysilane monomer, the hydroxyethoxy antibacterial silane coupling agent is generated.

[0009] Preferably, the ethoxysilane monomer is one of triethoxysilane, methyldiethoxysilane and dimethylethoxysilane.

[0010] Preferably, the preparation method of the aldehyde ethoxy antibacterial silane coupling agent is: through the nucleophilic substitution reaction of the hydroxyl functional group of the hydroxyethoxy antibacterial silane coupling agent and the chlorine functional group of 5-chloropentanal, the aldehyde ethoxy antibacterial silane coupling agent is generated.

[0011] Preferably, the particle size of the diatomite is 500-800 mesh, and the porosity is 70-90%.

[0012] Preferably, the particle size of the TiO2 nanoparticles is 5-20 nm.

[0013] The formula of an antibacterial and mildew-proof paint prepared according to the above method is: 50-70 parts by weight of polyurethane resin, 30-45 parts by weight of N,N-dimethylformamide, 5-15 parts by weight of diatomite, 5-20 parts by weight of the supported antibacterial and mildew-proof agent, 3-8 parts by weight of the composite additive, and 0.5-3 parts by weight of ethanolamine.

[0014] Preferably, the composite additive comprises one or a combination of several of a leveling agent, a thickening agent, a defoaming agent, a wetting agent, and a dispersing agent.

[0015] Advantages: The present application first designs and synthesizes a hydroxyethoxy antibacterial silane coupling agent and an aldehyde ethoxy antibacterial silane coupling agent using the bio-based antibacterial compound 4-terpenol, triethoxysilane and 5-chloropentanal as raw materials; Then, the present application modifies the surface of the porous carrier material diatomite with the hydroxyethoxy antibacterial silane coupling agent, further composites the natural antibacterial agent tea tree oil through hydrogen bonding to prepare a first supported antibacterial and mildew-proof agent. On the other hand, the present application modifies the surface of the porous carrier material diatomite with the hydroxyethoxy antibacterial silane coupling agent and the aldehyde ethoxy antibacterial silane coupling agent, simultaneously modifies the surface of the photocatalyst material TiO2 nanoparticles with the silane coupling agent KH540, modifies the TiO2 nanoparticles on the surface of the diatomite to prepare a diatomite / TiO2 composite material based on the Schiff base reaction, and further composites the natural antibacterial agent tea tree oil through hydrogen bonding to prepare a second supported antibacterial and mildew-proof agent. The supported antibacterial and mildew-proof agent is added as a modified component to the paint formula to prepare an antibacterial and mildew-proof paint, which has a mildew-proof grade of 0, an antibacterial rate of >95%, and shows very excellent antibacterial and mildew-proof effects and comprehensive performance, and has practical application value. DETAILED DESCRIPTION

[0016] The present application uses the natural antibacterial component 4-terpenol in tea tree oil as a raw material, and sequentially prepares a hydroxyethoxy antibacterial silane coupling agent and an aldehyde ethoxy antibacterial silane coupling agent through a silicon-hydrogen addition reaction and a nucleophilic substitution reaction; loads the natural antibacterial agent tea tree oil and / or the photocatalyst material TiO2 with antibacterial function on the diatomite substrate to prepare a supported antibacterial and mildew-proof agent using the hydroxyethoxy antibacterial silane coupling agent and / or the aldehyde ethoxy antibacterial silane coupling agent; and improves the problems of poor antibacterial and mildew-proof effect, poor durability, and insufficient environmental protection of the antibacterial and mildew-proof paint through the supported antibacterial and mildew-proof agent.

[0017] Experimental Example One Preparation of hydroxyethoxy antibacterial silane coupling agent: using 4-terpenol as raw material, the addition reaction of the Si-H functional group of ethoxysilane monomer and the alkenyl functional group of 4-terpenol occurs to generate hydroxyethoxy antibacterial silane coupling agent; Among them, the ethoxysilane monomer can be one of triethoxysilane, methyldiethoxysilane and dimethylethoxysilane; the chemical structural formula of the hydroxyethoxy antibacterial silane coupling agent prepared by using triethoxysilane in the experimental example is: The specific experimental steps for preparing the hydroxyethoxy antibacterial silane coupling agent are as follows: under the protection of nitrogen, 1.5g of 4-terpenol and 30mL of anhydrous isopropanol are added to a three-necked flask, stirred at room temperature until completely dissolved, then 1.8mL of triethoxysilane and 5 drops of Karstedt catalyst are added dropwise to the three-necked flask, heated to 85℃ and stirred to reflux for 4h, cooled to room temperature, rotary evaporation to remove the solvent, washed with anhydrous ethanol, vacuum dried to obtain the hydroxyethoxy antibacterial silane coupling agent; The nuclear magnetic resonance hydrogen spectrum of the hydroxyethoxy antibacterial silane coupling agent is characterized as follows: 1 H NMR (CDCI3, 400MHz) δ: 0.86-0.88 (d, 3H), 0.93-0.95 (d, 3H), 0.99-1.01 (d, 3H), 1.19-1.23 (t, 9H), 1.27-1.33 (m, 1H), 1.50-1.55 (m, 2H), 1.71-1.75 (t, 2H), 1.83-1.91 (m, 2H), 2.10-2.12 (d, 2H), 3.80-3.86 (m, 6H).

[0018] Experimental Example Two: Preparation of aldehyde ethoxy antibacterial silane coupling agent: the nucleophilic substitution reaction of the hydroxyl functional group of the hydroxyethoxy antibacterial silane coupling agent and the chlorine functional group of 5-chloropentanal occurs to generate aldehyde ethoxy antibacterial silane coupling agent, and its chemical structural formula is: The specific experimental steps for preparing the aldehyde ethoxy antibacterial silane coupling agent are as follows: 1.6g of the hydroxyethoxy antibacterial silane coupling agent and 30mL of anhydrous acetone are added to a three-necked flask, stirred at room temperature until completely dissolved, then 5mL of anhydrous acetone solution containing 0.6g of 5-chloropentanal and 2.5mL of triethylamine catalyst are added dropwise to the three-necked flask, heated to 60℃ and stirred to reflux for 5h, cooled to room temperature, rotary evaporation to remove the solvent, washed with anhydrous ethanol, vacuum dried to obtain the aldehyde ethoxy antibacterial silane coupling agent; The nuclear magnetic resonance hydrogen spectrum of the aldehyde ethoxy antibacterial silane coupling agent is characterized as follows: 1H NMR (CDC13, 400 MHz) δ: 0.84-0.86 (d, 3H), 0.91-0.93 (d, 3H), 0.96-0.98 (d, 3H), 1.19-1.23 (t, 9H), 1.35-1.41 (m, 1H), 1.48-1.53 (m, 2H), 1.59-1.65 (m, 4H), 1.72-1.76 (t, 2H), 1.83-1.89 (m, 1H), 1.95-2.02 (m, 1H), 2.14-2.16 (d, 2H), 2.39-2.44 (m, 2H), 3.42-3.45 (t, 2H), 3.79-3.85 (m, 6H).

[0019] Example One: The supported antibacterial and mildew-proof agent I was prepared by the following process: The modified diatomite I was prepared by the following method: the surface of the diatomite was modified by a hydroxyethoxy antibacterial silane coupling agent, and the silicon hydroxyl functional groups obtained by the hydrolysis reaction of the hydrolysis functional groups of the hydroxyethoxy antibacterial silane coupling agent were subjected to a dehydration condensation reaction with the hydroxyl functional groups on the surface of the hydroxylated diatomite (prepared by the following method), to obtain the modified diatomite I. The specific experimental steps are as follows: 8 g of hydroxylated diatomite, 40 mL of deionized water and 60 mL of ethanol were added to a three-necked flask, stirred and dissolved at room temperature for 30 min, and ultrasonically dispersed for 30 min. Then 2 g of the hydroxyethoxy antibacterial silane coupling agent and 5 drops of glacial acetic acid were added to the three-necked flask in sequence, and the temperature was raised to 60°C for stirring and reaction for 4 h. After cooling to room temperature, centrifugation was performed, and repeated washing with ethanol and deionized water was performed. Vacuum drying was performed at 80°C for 2 h to obtain the modified diatomite I. The preparation method of the hydroxylated diatomite is as follows: 10 g of diatomite powder (purchased from Hengxin Mineral Product Processing Factory in Lingshou County, particle size 600 mesh, porosity 85%) and 200 mL of hydrogen peroxide aqueous solution (30 wt%) were added to a round-bottom flask, and ultrasonically dispersed for 30 min. Under the action of mechanical stirring, the temperature was raised to 105°C for reflux reaction for 6 h. After cooling to room temperature, centrifugation was performed, and repeated washing with deionized water was performed. Vacuum drying was performed at 80°C for 5 h to obtain the hydroxylated diatomite. Preparation of the supported antibacterial and mildew-proof agent I, the preparation method is: through the hydrogen bond interaction of the hydroxyl functional groups contained in the modified diatomite I and the hydroxyl functional groups of the active components in tea tree oil, the natural antibacterial agent tea tree oil is supported on the diatomite matrix to obtain the supported antibacterial and mildew-proof agent I, and the specific experimental steps are as follows: 10 g of modified diatomite I and 100 mL of ethanol are added into a three-necked flask, stirred and dissolved at room temperature for 30 min, and ultrasonically dispersed for 1 h, 10 mL of the ethanol solution in which 2 g of tea tree oil (purchased from Jiangxi Zhonghuan Biotechnology Co., Ltd.) is dissolved is added dropwise into the three-necked flask, the temperature is increased to 60 DEG C, and stirring is carried out for 8 h, the solvent is removed by rotary evaporation, vacuum drying is carried out, and the supported antibacterial and mildew-proof agent I is obtained.

[0020] Example two: Preparation of the supported antibacterial and mildew-proof agent II, the preparation process is as follows: Preparation of the modified diatomite II, the preparation method is: the surface of the diatomite is modified by using hydroxyethoxy antibacterial silane coupling agent and aldehyde ethoxy antibacterial silane coupling agent, the silicon hydroxyl functional groups obtained by the hydrolysis reaction of the hydrolysis functional groups of the hydroxyethoxy antibacterial silane coupling agent and the aldehyde ethoxy antibacterial silane coupling agent and the hydroxyl functional groups on the surface of the hydroxylated diatomite are subjected to dehydration condensation reaction, and the modified diatomite II is obtained, and the specific experimental steps refer to the preparation experiment of the modified diatomite I, and the difference is that 1 g of hydroxyethoxy antibacterial silane coupling agent and 1 g of aldehyde ethoxy antibacterial silane coupling agent are used instead of 2 g of hydroxyethoxy antibacterial silane coupling agent; Preparation of the TiO2 nanoparticles modified by the silane coupling agent KH540: 5 g of hydrophilic nanometer titanium dioxide powder (purchased from Guangzhou Pengyuan Chemical Co., Ltd., particle size 5-20 nm), 40 mL of deionized water and 60 mL of ethanol are added into a three-necked flask, stirred and dissolved at room temperature for 30 min, and ultrasonically dispersed for 30 min, then 2 mL of the silane coupling agent KH540 and 5 drops of glacial acetic acid are added dropwise into the three-necked flask in sequence, the temperature is increased to 60 DEG C, and stirring is carried out for 2 h, the temperature is cooled to room temperature, centrifugation is carried out, and the ethanol and deionized water are repeatedly washed by centrifugation in sequence, and vacuum drying is carried out at 80 DEG C for 2 h, thereby obtaining the TiO2 nanoparticles modified by the silane coupling agent KH540; The diatomite / TiO2 composite material is prepared by the following method: Schiff base reaction between the aldehyde group functional groups on the surface of the modified diatomite II and the amino group functional groups on the surface of the TiO2 nanoparticles modified by the silane coupling agent KH540, so as to modify the TiO2 nanoparticles on the surface of the diatomite, thereby obtaining the diatomite / TiO2 composite material, and the specific experimental steps are as follows: 10 g of the modified diatomite II and 120 mL of ethanol are added into a three-necked flask, stirred and dissolved at room temperature for 30 min, ultrasonically dispersed for 1 h, then 1 g of the TiO2 nanoparticles modified by the silane coupling agent KH540 is added into the three-necked flask, the temperature is increased to 60 DEG C, and the reaction is carried out for 10 h under stirring, the temperature is cooled to room temperature, centrifuged, repeatedly washed by centrifugation with deionized water, and dried at 80 DEG C under vacuum for 2 h, thereby obtaining the diatomite / TiO2 composite material. The supported antibacterial and mildew-proof agent II is prepared by the following method: hydrogen bond interaction between the hydroxyl group functional groups contained in the diatomite / TiO2 composite material and the hydroxyl group functional groups of the active components in the tea tree oil, so as to load the natural antibacterial agent tea tree oil on the diatomite matrix, thereby obtaining the supported antibacterial and mildew-proof agent II, and the specific experimental steps refer to the preparation experiment of the supported antibacterial and mildew-proof agent I, and the difference is that 11 g of the diatomite / TiO2 composite material is used to replace 10 g of the modified diatomite I.

[0021] Example Three An antibacterial and mildew-proof coating, comprising the following raw materials in parts by weight: 60 parts of polyurethane resin (purchased from Dongguan Jiuru Plastic Raw Material Co., Ltd., model 5715); 35 parts of N,N-dimethylformamide (purchased from China Reagent Co., Ltd.); 10 parts of diatomite (purchased from Hengxin Mineral Product Processing Factory in Lingshou County, particle size 600 mesh, porosity 85%); 12 parts of the supported antibacterial and mildew-proof agent; 3 parts of leveling agent (purchased from Dongguan Yilian Chemical Technology Co., Ltd., model 2503); 2 parts of defoaming agent (purchased from Dongguan Yilian Chemical Technology Co., Ltd., model 2603); 1 part of dispersing agent (purchased from Dongguan Yilian Chemical Technology Co., Ltd., model 6226); 2 parts of ethanolamine (purchased from China Reagent Co., Ltd.); The supported antibacterial and mildew-proof agent is the supported antibacterial and mildew-proof agent I or the supported antibacterial and mildew-proof agent II.

[0022] Example Four A preparation method of an antibacterial and mildew-proof paint, comprising: adding polyurethane resin, leveling agent, defoaming agent and dispersing agent into N,N-dimethylformamide according to the formulation of the antibacterial and mildew-proof paint in Example 3, stirring and mixing at a rotating speed of 600 r / min for 1.5 h, adding diatomite after increasing the rotating speed to 1000 r / min and stirring and mixing for 30 min, then adding the supported antibacterial and mildew-proof agent under the rotating speed of 1000 r / min and stirring and mixing for 2 h, finally adding ethanol amine and stirring for 5 min, reducing the rotating speed to 150 r / min, and defoaming at a low speed for 30 min to obtain the antibacterial and mildew-proof paint. wherein when the supported antibacterial and mildew-proof agent is the supported antibacterial and mildew-proof agent I, the product obtained is recorded as antibacterial and mildew-proof paint I; and when the supported antibacterial and mildew-proof agent is the supported antibacterial and mildew-proof agent II, the product obtained is recorded as antibacterial and mildew-proof paint II.

[0023] Comparative Example 1 Preparation of paint a, which is different from the antibacterial and mildew-proof paint I only in that 10 parts by weight of diatomite (purchased from Hengxin Mineral Product Processing Factory in Lingshou County, particle size 600 mesh, porosity 85%) and 2 parts by weight of tea tree oil (purchased from Jiangxi Zhonghuan Biological Technology Co., Ltd.) are used to replace 12 parts of the supported antibacterial and mildew-proof agent.

[0024] Comparative Example 2 Preparation of paint b, which is different from the antibacterial and mildew-proof paint I only in that the supported antibacterial and mildew-proof agent is not used.

[0025] Performance test The tinplate is cleaned with anhydrous ethanol, and then the antibacterial and mildew-proof paint sample is sprayed on the tinplate by a spray gun (two rounds of spraying are performed on each sample plate on average, and the coating thickness is controlled to be 50 μm). After spraying, the sample plate is placed in a 80℃ air drying oven for curing for 3 h to form an antibacterial and mildew-proof coating for antibacterial and mildew-proof performance test. (1) Antibacterial performance test: the coating sample is tested for antibacterial performance according to HG / T 3950-2007 “Antibacterial Coatings”, the test bacteria are ATCC6538 type Staphylococcus aureus and ATCC25922 type Escherichia coli with a concentration of 1.0×10 6 CFU / mL, the test conditions are: relative humidity > 90%, temperature 37℃, and culture time 24 h, and the antibacterial rate of the coating sample is recorded; (2) Mildew-proof performance test: the coating sample is tested for mildew-proof performance according to GB / T 1741-2007 “Paint Film Resistance to Fungus Test Method”, the test bacteria are ATCC 16404 type Aspergillus niger with a concentration of 1.0×10 6 CFU / mL, the test time is 28 days, the test conditions are: relative humidity > 90%, temperature 28℃, and the mildew-proof grade of the coating sample is recorded; The experimental results are shown in Table 1 below.

[0026] Table 1 Experimental results of antibacterial and mildew-proof performance of the antibacterial and mildew-proof paint The following conclusions can be drawn from the experimental results in Table 1: The paint product prepared by using the self-developed supported antibacterial and mildew-proof agent has achieved significant improvement in antibacterial and mildew-proof performance, and has the beneficial technical effect of improving the antibacterial and mildew-proof performance; Among them, the hydroxyethoxy antibacterial silane coupling agent and the aldehyde ethoxy antibacterial silane coupling agent are used to load tea tree oil and photocatalyst TiO2 nanomaterials on diatomite matrix to prepare a supported antibacterial and mildew-proof agent II, and the antibacterial and mildew-proof paint prepared therefrom has better antibacterial effect; The basic performance of the antibacterial and mildew-proof paint is tested, and the test results are shown in Table 2 below. Table 2 Experimental results of basic performance of the antibacterial and mildew-proof paint The following conclusions can be drawn from the experimental results in Table 2: the antibacterial and mildew-proof paint prepared by the present application has better comprehensive performance and practical application value.

Claims

1. A method for preparing an antibacterial and antifungal coating, characterized in that, Includes the following steps: Step 1: Using 4-terpene alcohol as raw material, hydroxyethoxy antibacterial silane coupling agents and aldehyde ethoxy antibacterial silane coupling agents were prepared through hydrosilylation and nucleophilic substitution reactions. Step 2: Prepare a supported antibacterial and antifungal agent, which is either supported antibacterial and antifungal agent I or supported antibacterial and antifungal agent II; Among them, the supported antibacterial and antifungal agent I is prepared by first modifying the surface of diatomaceous earth with a hydroxyethoxy antibacterial silane coupling agent, and then compounding it with tea tree oil through hydrogen bonding. The mass ratio of the hydroxyethoxylated antibacterial silane coupling agent, diatomaceous earth, and tea tree oil in the supported antibacterial and antifungal agent I is (0.5-2):(3-8):1; The supported antibacterial and antifungal agent II is prepared by first modifying the surface of diatomaceous earth with a combination of hydroxyethoxy antibacterial silane coupling agent and aldehyde ethoxy antibacterial silane coupling agent, and then loading TiO2 nanoparticles modified with silane coupling agent KH540 onto the surface of diatomaceous earth based on the Schiff base reaction, and then combining them with tea tree oil through hydrogen bonding. The mass ratio of hydroxyethoxy antibacterial silane coupling agent, aldehyde ethoxy antibacterial silane coupling agent, diatomaceous earth, TiO2 nanoparticles and tea tree oil in the supported antibacterial and antifungal agent II is (0.2-1):(0.2-1):(3-8):(0.1-1):1; Step 3: Add the loaded antibacterial and antifungal agent as a modifying component to the coating formulation to prepare an antibacterial and antifungal coating.

2. The method for preparing an antibacterial and antifungal coating according to claim 1, characterized in that, The preparation method of the hydroxyethoxy antibacterial silane coupling agent is as follows: using 4-terpene alcohol as raw material, the alkenyl functional group of 4-terpene alcohol undergoes an addition reaction with the Si-H functional group of ethoxysilane monomer to generate the hydroxyethoxy antibacterial silane coupling agent.

3. The method for preparing an antibacterial and antifungal coating according to claim 2, characterized in that, The ethoxysilane monomer is one of triethoxysilane, methyldiethoxysilane, and dimethylethoxysilane.

4. The method for preparing an antibacterial and antifungal coating according to claim 1, characterized in that, The preparation method of the aldehyde ethoxy antibacterial silane coupling agent is as follows: the hydroxyl functional group of the aldehyde ethoxy antibacterial silane coupling agent undergoes a nucleophilic substitution reaction with the chlorine functional group of 5-chloropentanal to generate the aldehyde ethoxy antibacterial silane coupling agent.

5. The method for preparing an antibacterial and antifungal coating according to claim 1, characterized in that, The diatomaceous earth has a particle size of 500-800 mesh and a porosity of 70-90%.

6. The method for preparing an antibacterial and antifungal coating according to claim 1, characterized in that, The TiO2 nanoparticles have a particle size of 5-20 nm.

7. An antibacterial and antifungal coating prepared according to any one of claims 1-6, characterized in that, The formulation of the antibacterial and antifungal coating is as follows: 50-70 parts by weight of polyurethane resin, 30-45 parts by weight of N,N-dimethylformamide, 5-15 parts by weight of diatomaceous earth, 5-20 parts by weight of loaded antibacterial and antifungal agent, 3-8 parts by weight of composite additives, and 0.5-3 parts by weight of ethanolamine.

8. The antibacterial and antifungal coating according to claim 7, characterized in that, The composite additive includes one or more of the following: leveling agent, thickener, defoamer, wetting agent, and dispersant.

9. The application of the antibacterial and antifungal coating according to claim 7 in the field of environmentally friendly building materials.

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