Preparation method of silver-loaded titanium dioxide polyurea hybrid microcapsule and application of silver-loaded titanium dioxide polyurea hybrid microcapsule in coating

Abstract

The invention discloses a preparation method of a silver-loaded titanium dioxide polyurea hybrid microcapsule and application of the silver-loaded titanium dioxide polyurea hybrid microcapsule in paint, and belongs to the technical field of antibacterial materials.The preparation method comprises the steps of preparing a silver-loaded titanium dioxide dispersion liquid, preparing a wall material and core material oil-in-water mixed liquid and preparing the microcapsule. When the concentration of the prepared silver-loaded titanium dioxide polyurea hybrid microcapsule dispersion liquid is 3wt%, the antibacterial rate on escherichia coli and staphylococcus aureus reaches 99.9% within 0.5 hour; after the prepared silver-loaded titanium dioxide polyurea hybrid microcapsule is added into a coating to prepare an antibacterial coating, the prepared coating has good antibacterial performance and can emit pleasant fragrance.

Description

Technical Field

[0001] The invention belongs to the technical field of antibacterial materials, and in particular relates to a preparation method of silver-loaded titanium dioxide polyurea hybrid microcapsules and an application of the microcapsules in coatings. Background Art

[0002] In daily life, bacteria and other microorganisms can attach and reproduce on common interfaces such as walls and furniture, providing conditions for disease transmission and cross-infection. Applying antibacterial coatings on interfaces is an effective way to reduce the harm of bacteria to the human body. Antibacterial coatings should have high efficiency and lasting antibacterial properties. Compared with organic antibacterial agents, inorganic antibacterial agents have a more lasting antibacterial effect. Inorganic antibacterial agents can be considered as additives for antibacterial coatings. Among inorganic antibacterial agents, silver-loaded titanium dioxide nanoparticles have attracted much attention due to their broad-spectrum antibacterial, high efficiency and long-lasting characteristics. However, the small particle size and high surface energy of silver-loaded titanium dioxide nanoparticles make them very easy to agglomerate. If directly applied to organic substrates (such as coatings, fabric finishing agents, etc.), uneven dispersion will occur, resulting in reduced or ineffective antibacterial performance. Therefore, improving the dispersibility of silver-loaded titanium dioxide nanoparticles in organic coatings is the key to preparing antibacterial coatings.

[0003] A common method to improve the dispersibility of silver-loaded titanium dioxide nanoparticles is to disperse the nanoparticles in water and add additives such as pH adjusters, surfactants or coupling agents to allow the nanoparticles to form a uniformly dispersed dispersion in water. The added additives may change the acidity and alkalinity of the dispersion, and if mixed with the coating, it may affect the basic performance of the coating. In addition, the content of silver-loaded titanium dioxide in the dispersion is often low, generally with a mass fraction of a few thousandths to a few percent. Low content of silver-loaded titanium dioxide may lead to decreased antibacterial properties. When a low-content silver-loaded titanium dioxide dispersion is mixed with a coating, the coating may be over-diluted, making it difficult for the coating to form a film.

[0004] In summary, the silver-loaded titanium dioxide dispersion obtained by the existing dispersion technology has poor compatibility with the organic substrate, which is not conducive to the application of the silver-loaded titanium dioxide antibacterial agent in coatings. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a preparation method of silver-loaded titanium dioxide polyurea hybrid microcapsules and the application of the microcapsules in coatings. Inorganic silver-loaded titanium dioxide nanoparticles are grafted onto organic polyurea microcapsules through a silane coupling agent, thereby improving the dispersibility of the inorganic silver-loaded titanium dioxide nanoparticles. At the same time, the organic polyurea microcapsules as carriers improve the compatibility with organic substrate coatings. After the silver-loaded titanium dioxide polyurea hybrid microcapsules are added to the coating to prepare an antibacterial coating, the prepared coating has antibacterial properties and can also emit a fragrant odor, thereby increasing the added value of the antibacterial product.

[0006] The specific technical solution of the present invention is as follows: A preparation method of silver-loaded titanium dioxide polyurea hybrid microcapsules, the preparation method comprising preparing a silver-loaded titanium dioxide dispersion, preparing a water-in-oil emulsion of wall material and core material, and preparing microcapsules; The preparation of the silver-loaded titanium dioxide dispersion includes anion dispersant dispersion and silane coupling agent coupling; The preparation of the water-in-oil emulsion of wall material and core material includes preparing an aqueous phase liquid, preparing an oil phase liquid, and preparing a water-in-oil emulsion; The preparation of the microcapsules includes introducing a catalyst and introducing the silver-loaded titanium dioxide dispersion.

[0007] The method of anion dispersant dispersion is to add an anion dispersant to deionized water, use a magnetic stirrer at 25±1°C and 300-500 r / min, stir for 20-30 min; then add silver-loaded titanium dioxide nanoparticles and stir for 20-30 min to obtain an anion dispersant dispersion; The method of silane coupling agent coupling is to add a silane coupling agent ethanol solution to the anion dispersant dispersion and continue stirring for 20-30 min; after stirring, place the beaker in an ice-water bath and use an ultrasonic crusher for ultrasonic treatment for 30 min, the power of the ultrasonic crusher is 50-60%, and stir with a magnetic stirrer during ultrasonic crushing to obtain a silver-loaded titanium dioxide dispersion.

[0008] The method of preparing the aqueous phase liquid is to add an emulsifier to deionized water, heat in a water bath to 40-50°C, use a magnetic stirrer at 300-500 r / min, and stir for 10-20 min to obtain an aqueous phase liquid; The method of preparing the oil phase liquid is to fully stir and mix a prepolymer monomer and a plant essential oil, use a magnetic stirrer at 300-500 r / min at room temperature, and stir for 10-20 min to obtain an oil phase liquid; The method of preparing the water-in-oil emulsion is to mix the aqueous phase liquid and the oil phase liquid, use a homogenizer at 8000-10000 r / min, and perform high-speed shearing for 3 min to obtain a water-in-oil emulsion.

[0009] The method of introducing the catalyst is to place the water-in-oil emulsion in a constant temperature oil bath at 75-85°C, use a magnetic stirrer at 200-400 r / min for stirring, keep warm for 5 min, and then slowly drop in the catalyst to initiate the self-polymerization reaction of the prepolymer monomer to obtain a self-polymerization reaction liquid; The method of introducing the silver-loaded titanium dioxide dispersion is to slowly drop the silver-loaded titanium dioxide dispersion into the self-polymerization reaction liquid, keep warm in a constant temperature oil bath at 75-85°C for 4-5 h and then end the reaction; centrifuge the reaction liquid and freeze-dry the precipitate for 24 h to obtain silver-loaded titanium dioxide polyurea hybrid microcapsules.

[0010] The anionic dispersant includes one or both of sodium dodecylbenzenesulfonate and sodium dodecyl sulfate; The particle size of the silver-loaded titanium dioxide nanoparticles is 30 - 50 nm.

[0011] The silane coupling agent is N-β-aminoethyl-γ-aminopropyltrimethoxysilane (KH792); The ethanol solution of the silane coupling agent is prepared according to the mass ratio of 20 parts of silane coupling agent : 72 parts of absolute ethanol : 8 parts of deionized water; In the silver-loaded titanium dioxide dispersion, the masses of the silver-loaded titanium dioxide nanoparticles, the anionic dispersant, and the ethanol solution of the silane coupling agent respectively account for 1 - 3 wt%, 1 - 3 wt%, and 1 - 5 wt% of the total mass of the silver-loaded titanium dioxide dispersion.

[0012] The emulsifier is polyvinyl alcohol; The prepolymer monomer is isophorone diisocyanate; The plant essential oil includes one or more of pine essential oil, peppermint essential oil, tea tree essential oil, agarwood essential oil, and mugwort essential oil; In the oil-in-water mixture, the masses of the emulsifier, the prepolymer monomer, and the plant essential oil respectively account for 1 - 3 wt%, 5 - 9 wt%, and 20 - 40 wt% of the total mass of the mixture.

[0013] The catalyst is tetramethylethylenediamine; The mass ratio of the catalyst to the prepolymer monomer is 2 : 2 - 3; The mass ratio of the oil-in-water mixture to the silver-loaded titanium dioxide dispersion is 1 : 1.

[0014] Application of the above silver-loaded titanium dioxide polyurea hybrid microcapsules in coatings, and the method of the application includes preparation of antibacterial liquid, preparation of antibacterial coating, and preparation of antibacterial coating; The method for preparing the antibacterial liquid is to mix the silver-loaded titanium dioxide polyurea hybrid microcapsules with deionized water, stir with a magnetic stirrer at 200 - 400 r / min for 30 min to obtain the antibacterial liquid; The method for preparing the antibacterial coating is to mix the antibacterial liquid with a coating curing agent, shear and stir with a high-speed shear stirrer at 200 r / min. After stirring for 10 min, add the coating film-forming component and continue to shear and stir for 10 min to obtain the antibacterial coating; The method for preparing the antibacterial coating is to apply the antibacterial coating on a glass slide and let it stand at room temperature for drying for more than 48 h to obtain the antibacterial coating.

[0015] The solid content of the silver-loaded titanium dioxide polyurea hybrid microcapsules in the antibacterial liquid is 10 - 50%; The mass ratio of the coating curing agent to the coating film-forming component is 15:100, and the mass ratio of the coating curing agent to the antibacterial liquid is 1:1; The coating amount of the antibacterial coating is 1 mg / cm 2 .

[0016] Compared with the prior art, the present invention has the following beneficial effects: Compared with unmodified silver-loaded titanium dioxide, the silver-loaded titanium dioxide polyurea hybrid microcapsules prepared by the present invention have a reduced degree of self-aggregation, a shortened time to achieve the same antibacterial effect, a reduced amount of antibacterial agent used, and a savings in the preparation cost of antibacterial materials; the silver-loaded titanium dioxide polyurea hybrid microcapsules can be well dispersed in the organic substrate, solving the dispersion problem of the silver-loaded titanium dioxide antibacterial agent in the coating; Compared with unmodified polyurea microcapsules, the silver-loaded titanium dioxide polyurea hybrid microcapsules prepared by the present invention retain the fragrant smell while increasing the antibacterial performance. The antibacterial rate of a 3 wt% silver-loaded titanium dioxide polyurea hybrid microcapsule dispersion against Escherichia coli and Staphylococcus aureus reaches 99.9% in 0.5 hour; After the silver-loaded titanium dioxide polyurea hybrid microcapsules prepared by the present invention are added to the coating to prepare an antibacterial coating, the prepared coating has antibacterial performance and can also emit a pleasant fragrance. The antibacterial rate against Escherichia coli is 99.8%, and the antibacterial rate against Staphylococcus aureus is 97.9%. Detailed implementation mode

[0017] Example 1 A preparation method of silver-loaded titanium dioxide polyurea hybrid microcapsules (1) Preparation of silver-loaded titanium dioxide dispersion a. Dispersion with an anionic dispersant Add the anionic dispersant to deionized water, use a magnetic stirrer at 500 r / min at 25°C and stir for 30 min; then add silver-loaded titanium dioxide nanoparticles and stir for 30 min to obtain an anionic dispersant dispersion; The anionic dispersant is sodium dodecyl sulfate; The sodium dodecyl sulfate is an organic anionic dispersant, and the long chain can generate steric hindrance, which helps to improve the dispersion of silver-loaded titanium dioxide and can also reduce the interfacial tension; The particle size of the silver-loaded titanium dioxide nanoparticles is 30 nm.

[0018] b. Coupling with a silane coupling agent Add a silane coupling agent ethanol solution to the anionic dispersant dispersion and continue stirring for 30 min; after stirring, place the beaker in an ice-water bath and use an ultrasonic crusher for ultrasonic treatment for 30 min. The power of the ultrasonic crusher is 60%, and stirring is carried out with a magnetic stirrer during ultrasonic crushing to obtain a silver-loaded titanium dioxide dispersion; The silane coupling agent is N-β-aminoethyl-γ-aminopropyltrimethoxysilane (KH792); The selection of silane coupling agent is the key to the preparation of silver-loaded titanium dioxide polyurea hybrid microcapsules. Not all silane coupling agents are suitable for the preparation of the silver-loaded titanium dioxide polyurea hybrid microcapsules of the present invention. For example, the inventors found in the experiment that when KH550 is used as the silane coupling agent, the self-polymerization process of the microcapsules is interrupted and silver-loaded titanium dioxide polyurea hybrid microcapsules cannot be formed; when KH792 is used as the silane coupling agent, KH792 has a diamino structure and can act as a chain extender, so that silver-loaded titanium dioxide can be grafted onto the polyurea microcapsule shell to obtain silver-loaded titanium dioxide polyurea hybrid microcapsules; The silane coupling agent ethanol solution is prepared according to the mass ratio of 20 parts of silane coupling agent: 72 parts of anhydrous ethanol: 8 parts of deionized water; In the silver-loaded titanium dioxide dispersion, the masses of the silver-loaded titanium dioxide nanoparticles, the anionic dispersant, and the silane coupling agent ethanol solution account for 1 wt%, 1 wt%, and 2.5 wt% of the total mass of the silver-loaded titanium dioxide dispersion, respectively.

[0019] (2) Preparation of water-in-oil mixture for wall and core materials a. Preparation of aqueous liquid Add the emulsifier to deionized water, heat the mixture to 40°C in a water bath, and stir at 300 rpm with a magnetic stirrer for 10 min to obtain an aqueous phase liquid. The emulsifier is polyvinyl alcohol; The choice of emulsifier will affect the morphology of the prepared microcapsules. Not all emulsifiers are suitable for preparing the silver-loaded titanium dioxide polyurea hybrid microcapsules of the present invention. For example, the inventors found during the experiment that when gum arabic was used as an emulsifier, the surface of the prepared microcapsules was severely concave, and the silver-loaded titanium dioxide could not be evenly grafted onto the microcapsule shell; when polyvinyl alcohol was used as an emulsifier, the prepared microcapsules were in a complete spherical shape, which was conducive to the grafting of silver-loaded titanium dioxide onto the microcapsule shell.

[0020] b. Preparation of oil phase liquid The prepolymer monomer and the plant essential oil were fully stirred and mixed, and stirred for 20 minutes at 300 r / min using a magnetic stirrer at room temperature to obtain an oil phase liquid; The prepolymer monomer is isophorone diisocyanate; The plant essential oil is pine essential oil.

[0021] c. Preparation of oil-in-water mixture The water phase liquid and the oil phase liquid were mixed, and high-speed shearing was performed for 3 minutes using a homogenizer at 10000 r / min to obtain an oil-in-water mixed liquid; In the oil-in-water mixture, the masses of the emulsifier, prepolymer monomer, and plant essential oil account for 1 wt%, 7.5 wt%, and 30 wt% of the total mass of the mixture, respectively.

[0022] (3)Preparation of microcapsules a. Introduction of catalyst Place the oil-in-water mixture in an 80 °C constant-temperature oil bath, stir it at 200 r / min using a magnetic stirrer for 5 min, and then slowly drop in the catalyst to initiate the self-polymerization reaction of the prepolymer monomer to obtain a self-polymerization reaction solution.

[0023] b. Introduction of silver-loaded titanium dioxide dispersion Slowly drop the silver-loaded titanium dioxide dispersion into the self-polymerization reaction solution, keep it warm in an 80 °C constant-temperature oil bath for 4 h, and then end the reaction; centrifuge the reaction solution, and freeze-dry the precipitate for 24 h to obtain silver-loaded titanium dioxide polyurea hybrid microcapsules; The catalyst is N,N,N',N'-tetramethylethylenediamine; The mass ratio of the catalyst to the prepolymer monomer is 4:5; The mass ratio of the oil-in-water mixture to the silver-loaded titanium dioxide dispersion is 1:1.

[0024] Comparative Example 1 A preparation method of polyurea microcapsules On the basis of Example 1, the step of preparing the silver-loaded titanium dioxide dispersion is omitted, and the silver-loaded titanium dioxide dispersion is not added in the step of preparing the microcapsules, and the remaining steps are the same to obtain unmodified polyurea microcapsules.

[0025] Example 2 A preparation method of silver-loaded titanium dioxide polyurea hybrid microcapsules (1)Preparation of silver-loaded titanium dioxide dispersion a. Dispersion with anionic dispersant Add the anionic dispersant to deionized water, stir it at 300 r / min using a magnetic stirrer at 25 °C for 20 min; then add the silver-loaded titanium dioxide nanoparticles and stir for 20 min to obtain an anionic dispersant dispersion; The anionic dispersant is sodium dodecylbenzenesulfonate; The particle size of the silver-loaded titanium dioxide nanoparticles is 50 nm.

[0026] b. Coupling with silane coupling agent Add the silane coupling agent ethanol solution to the anionic dispersant dispersion and continue stirring for 20 min; after stirring, place the beaker in an ice-water bath and perform ultrasonic treatment with an ultrasonic crusher for 30 min. The power of the ultrasonic crusher is 50%, and stirring is carried out with a magnetic stirrer during ultrasonic comminution to obtain a silver-loaded titanium dioxide dispersion; The silane coupling agent is N-β-aminoethyl-γ-aminopropyltrimethoxysilane (KH792); The silane coupling agent ethanol solution is prepared according to the mass ratio of 20 parts of silane coupling agent: 72 parts of anhydrous ethanol: 8 parts of deionized water; In the silver-loaded titanium dioxide dispersion, the masses of the silver-loaded titanium dioxide nanoparticles, the anionic dispersant, and the silane coupling agent ethanol solution account for 2wt%, 2wt%, and 5wt% of the total mass of the silver-loaded titanium dioxide dispersion, respectively.

[0027] (2) Preparation of water-in-oil mixture for wall and core materials a. Preparation of aqueous liquid Add the emulsifier to deionized water, heat the mixture to 40°C in a water bath, and stir at 400 rpm with a magnetic stirrer for 10 min to obtain an aqueous phase liquid. The emulsifier is polyvinyl alcohol.

[0028] b. Preparation of oil phase liquid The prepolymer monomer and the plant essential oil were fully stirred and mixed, and stirred for 20 minutes at 300 r / min using a magnetic stirrer at room temperature to obtain an oil phase liquid; The prepolymer monomer is isophorone diisocyanate; The plant essential oil is peppermint essential oil.

[0029] c. Preparation of oil-in-water mixture The water phase liquid and the oil phase liquid were mixed, and high-speed shearing was performed for 3 minutes using a homogenizer at 9000 r / min to obtain an oil-in-water mixed liquid; In the oil-in-water mixed liquid, the masses of the emulsifier, the prepolymer monomer and the plant essential oil account for 2wt%, 9wt% and 40wt% of the total mass of the mixed liquid respectively.

[0030] (3) Preparation of microcapsules a. Introduction of catalyst The water-in-oil mixture was placed in a constant temperature oil bath at 85° C. and stirred at 300 r / min using a magnetic stirrer. The mixture was kept warm for 5 minutes, and then the catalyst was slowly dropped into the mixture to initiate the self-polymerization reaction of the pre-polymerized monomers, thereby obtaining a self-polymerization reaction liquid.

[0031] b. Introducing silver-loaded titanium dioxide dispersion Slowly dripping the silver-loaded titanium dioxide dispersion into the self-polymerization reaction liquid, and then keeping the mixture in a constant temperature oil bath at 85° C. for 5 hours to terminate the reaction; centrifuging the reaction liquid, and freeze-drying the precipitate for 24 hours to obtain silver-loaded titanium dioxide polyurea hybrid microcapsules; The catalyst is tetramethylethylenediamine; The mass ratio of the catalyst to the prepolymer monomer is 2:3; The mass ratio of the oil-in-water mixture to the silver-loaded titanium dioxide dispersion is 1:1.

[0032] Example 3 Application method of the silver-loaded titanium dioxide polyurea hybrid microcapsules prepared in Example 1 in coatings (1) Preparation of the antibacterial liquid Mix the silver-loaded titanium dioxide polyurea hybrid microcapsules with deionized water, and stir with a magnetic stirrer at 200 r / min for 30 min to obtain the antibacterial liquid; The solid content of the silver-loaded titanium dioxide polyurea hybrid microcapsules in the antibacterial liquid is 20%.

[0033] (2) Preparation of the antibacterial coating Mix the antibacterial liquid with the coating curing agent, shear and stir with a high-speed shear stirrer at 200 r / min. After stirring for 10 min, add the coating film-forming component and continue to shear and stir for 10 min to obtain the antibacterial coating; The mass ratio of the coating curing agent to the coating film-forming component is 15:100, and the mass ratio of the coating curing agent to the antibacterial liquid is 1:1.

[0034] (3) Preparation of the antibacterial coating Apply the antibacterial coating on a glass slide and leave it to dry at room temperature for more than 48 h to obtain the antibacterial coating; The size of the glass slide is 5*5 cm. After cleaning with dishwashing liquid, ultrasonically clean it with absolute ethanol for 30 min, and dry it for later use; The coating amount of the antibacterial coating is 1 mg / cm 2 .

[0035] Preparation method of the unmodified coating in Comparative Example 2 On the basis of Example 3, omit the step of preparing the antibacterial liquid, and do not add the antibacterial liquid during the coating preparation process. The remaining steps are the same to obtain the unmodified coating.

[0036] Example 4 Antibacterial ability test of the microcapsules Carry out antibacterial performance tests on the silver-loaded titanium dioxide polyurea hybrid microcapsules and polyurea microcapsules in Examples 1-2 and Comparative Example 1. Use the method of GB / T 21510-2008 for antibacterial testing, prepare antibacterial liquids with different concentrations for testing, and test the antibacterial rates at different times. The results are shown in Table 1; The concentrations are 1, 3, and 5 wt% respectively, and the times are 0.5, 1, 1.5, 2, and 24 h respectively.

[0037] Table 1

[0038] Note: "-" indicates that the antibacterial rate is less than 10%.

[0039] Antibacterial Ability Test of the Coating in Example 5 The coatings of Example 3 and Comparative Example 2 were subjected to antibacterial performance tests. The antibacterial tests were carried out using the method of GB / T 21866-2008 to obtain the antibacterial rate. The results are shown in Table 2.

[0040] Table 2

[0041] Note: "-" indicates that the antibacterial rate is less than 10%.

Claims

1. A preparation method of silver-loaded titanium dioxide polyurea hybrid microcapsules, characterized in that, The preparation method includes preparing a silver-loaded titanium dioxide dispersion liquid, preparing a water-in-oil mixture of wall material and core material, and preparing microcapsules; The preparation of the silver-loaded titanium dioxide dispersion liquid includes anion dispersant dispersion and silane coupling agent coupling; The preparation of the water-in-oil mixture of wall material and core material includes preparing an aqueous phase liquid, preparing an oil phase liquid, and preparing a water-in-oil mixture; The preparation of microcapsules includes introducing a catalyst and introducing a silver-loaded titanium dioxide dispersion liquid.

2. The preparation method of a silver-loaded titanium dioxide polyurea hybrid microcapsule according to claim 1, characterized in that: The method of anion dispersant dispersion is to add an anion dispersant to deionized water, use a magnetic stirrer at 25±1°C and 300-500 r / min, stir for 20-30 min; then add silver-loaded titanium dioxide nanoparticles and stir for 20-30 min to obtain an anion dispersant dispersion liquid; The method of silane coupling agent coupling is to add a silane coupling agent ethanol solution to the anion dispersant dispersion liquid and continue stirring for 20-30 min; after stirring, place the beaker in an ice-water bath and perform ultrasonic treatment with an ultrasonic crusher for 30 min. The power of the ultrasonic crusher is 50-60%, and while ultrasonic pulverization, use a magnetic stirrer for stirring to obtain a silver-loaded titanium dioxide dispersion liquid.

3. The preparation method of a silver-loaded titanium dioxide polyurea hybrid microcapsule according to claim 1, characterized in that: The method of preparing the aqueous phase liquid is to add an emulsifier to deionized water, heat it in a water bath to 40-50°C, use a magnetic stirrer at 300-500 r / min, and stir for 10-20 min to obtain an aqueous phase liquid; The method of preparing the oil phase liquid is to fully stir and mix the prepolymer monomer and plant essential oil, use a magnetic stirrer at 300-500 r / min at room temperature, and stir for 10-20 min to obtain an oil phase liquid; The method of preparing the water-in-oil mixture is to mix the aqueous phase liquid and the oil phase liquid, and use a homogenizer at 8000-10000 r / min for high-speed shearing for 3 min to obtain a water-in-oil mixture.

4. The preparation method of a silver-loaded titanium dioxide polyurea hybrid microcapsule according to claim 1, characterized in that: The method of introducing the catalyst is to place the water-in-oil mixture in a constant temperature oil bath at 75-85°C, use a magnetic stirrer at 200-400 r / min for stirring, keep warm for 5 min, and then slowly drop the catalyst to initiate the self-polymerization reaction of the prepolymer monomer to obtain a self-polymerization reaction liquid; The method of introducing the silver-loaded titanium dioxide dispersion liquid is to slowly drop the silver-loaded titanium dioxide dispersion liquid into the self-polymerization reaction liquid, keep warm in a constant temperature oil bath at 75-85°C for 4-5 h and then end the reaction; centrifuge the reaction liquid and perform freeze-drying on the precipitate for 24 h to obtain a silver-loaded titanium dioxide polyurea hybrid microcapsule.

5. The preparation method of a silver-loaded titanium dioxide polyurea hybrid microcapsule according to claim 2, characterized in that: The anion dispersant includes one or two of sodium dodecylbenzenesulfonate and sodium dodecyl sulfate; The particle size of the silver-loaded titanium dioxide nanoparticles is 30-50 nm.

6. The preparation method of a silver-loaded titanium dioxide polyurea hybrid microcapsule according to claim 2, characterized in that: The silane coupling agent is N-β-aminoethyl-γ-aminopropyltrimethoxysilane (KH792); The ethanol solution of the silane coupling agent is prepared according to the mass ratio of 20 parts of silane coupling agent: 72 parts of absolute ethanol: 8 parts of deionized water; In the silver-loaded titanium dioxide dispersion, the masses of silver-loaded titanium dioxide nanoparticles, anionic dispersant, and the ethanol solution of the silane coupling agent respectively account for 1-3 wt%, 1-3 wt%, and 1-5 wt% of the total mass of the silver-loaded titanium dioxide dispersion.

7. The preparation method of a silver-loaded titanium dioxide polyurea hybrid microcapsule according to claim 3, characterized in that: The emulsifier is polyvinyl alcohol; The prepolymer monomer is isophorone diisocyanate; The plant essential oil includes one or more of pine essential oil, peppermint essential oil, tea tree essential oil, agarwood essential oil, and mugwort essential oil; In the oil-in-water mixture, the masses of the emulsifier, prepolymer monomer, and plant essential oil respectively account for 1-3 wt%, 5-9 wt%, and 20-40 wt% of the total mass of the mixture.

8. The preparation method of a silver-loaded titanium dioxide polyurea hybrid microcapsule according to claim 4, characterized in that: The catalyst is tetramethylethylenediamine; The mass ratio of the catalyst to the prepolymer monomer is 2:2-3; The mass ratio of the oil-in-water mixture to the silver-loaded titanium dioxide dispersion is 1:

1.

9. The application of the silver-loaded titanium dioxide polyurea hybrid microcapsule prepared by the preparation method according to any one of claims 1-8 in coatings, characterized in that: The method of the application includes antibacterial liquid preparation, antibacterial coating preparation, and antibacterial coating preparation; The method of preparing the antibacterial liquid is to mix the silver-loaded titanium dioxide polyurea hybrid microcapsule with deionized water, stir with a magnetic stirrer at 200-400 r / min for 30 min to obtain the antibacterial liquid; The method of preparing the antibacterial coating is to mix the antibacterial liquid with a coating curing agent, shear and stir with a high-speed shear stirrer at 200 r / min, after stirring for 10 min, add a coating film-forming component, and continue to shear and stir for 10 min to obtain the antibacterial coating; The method of preparing the antibacterial coating is to apply the antibacterial coating on a glass sheet and leave it to stand and dry at room temperature for more than 48 h to obtain the antibacterial coating.

10. The application of the silver-loaded titanium dioxide polyurea hybrid microcapsule according to claim 9 in coatings, characterized in that: The solid content of the silver-loaded titanium dioxide polyurea hybrid microcapsule in the antibacterial liquid is 10-50%; The mass ratio of the coating curing agent to the coating film-forming component is 15:100, and the mass ratio of the coating curing agent to the antibacterial liquid is 1:1; The coating amount of the antibacterial coating is 1 mg / cm 2 .

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