Antibacterial environment-friendly emulsion paint

Abstract

This invention discloses an antibacterial and environmentally friendly latex paint, comprising the following raw materials in parts by weight: 200-300 parts by weight of acrylic emulsion, 30-50 parts by weight of bentonite or functionalized bentonite, 50-100 parts by weight of calcium carbonate, 1-5 parts by weight of polyacrylamide, 5-20 parts by weight of polyoxypropylene polyoxyethylene glycerol ether, 0.5-2 parts by weight of stearamide, 2-8 parts by weight of film-forming agent, 0.1-3 parts by weight of leveling agent, 1-5 parts by weight of hydroxypropyl methylcellulose, 3-9 parts by weight of defoamer, 0.1-1 parts by weight of sodium bicarbonate, 120-240 parts by weight of water, and 5-15 parts by weight of multifunctional antibacterial agent. This antibacterial and environmentally friendly latex paint not only has good antibacterial, antifungal, waterproof, and stain-resistant properties, but also can absorb and degrade harmful gases such as formaldehyde in the surrounding environment, making it green and environmentally friendly.

Description

Technical Field

[0001] This invention belongs to the field of latex paint technology, specifically relating to an antibacterial and environmentally friendly latex paint. Background Technology

[0002] Latex paint is a water-based coating formulated with polymer emulsions as the film-forming agent and other additives and fillers. Latex paint offers good decorative effects, is easy to apply, and is washable and weather-resistant. However, it is also prone to mold growth, peeling, and performance degradation during use. Therefore, improving the antibacterial and antifungal properties of latex paint is essential. Chinese patent CN108441048A discloses an interior wall latex paint made from the following raw materials: potassium citrate, sodium persulfate, acrylic emulsion, calcium carbonate, anatase, bentonite, calcium fluoride, decabromodiphenyl ethane, tetraethylammonium hydroxide methanol solution, trimethylamine hydrochloride, barium sulfate, ethanol, zinc oxide, and water. This interior wall latex paint produces a smooth, fine film with high stability, is non-toxic and odorless, and can protect and beautify interior walls. However, the resulting paint film has poor antifungal and antibacterial properties, affecting its service life. Summary of the Invention

[0003] To address the shortcomings of the existing technology, the present invention provides an antibacterial and environmentally friendly latex paint.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0005] An antibacterial and environmentally friendly latex paint comprises the following raw materials in parts by weight: 200-300 parts by weight of acrylic emulsion, 30-50 parts by weight of bentonite or functionalized bentonite, 50-100 parts by weight of calcium carbonate, 1-5 parts by weight of polyacrylamide, 5-20 parts by weight of polyoxypropylene polyoxyethylene glycerol ether, 0.5-2 parts by weight of stearamide, 2-8 parts by weight of film-forming agent, 0.1-3 parts by weight of leveling agent, 1-5 parts by weight of hydroxypropyl methylcellulose, 3-9 parts by weight of defoamer, 0.1-1 parts by weight of sodium bicarbonate, 120-240 parts by weight of water, and 5-15 parts by weight of multifunctional antibacterial agent.

[0006] This invention uses acrylic emulsion as the main raw material and bentonite and calcium carbonate as fillers. This not only brightens the color of the latex paint but also effectively improves its mechanical properties. Polyacrylamide is used as a dispersant to improve the dispersion performance of the raw materials, preventing agglomeration and ensuring the stability of the latex paint. Polyoxypropylene polyoxyethylene glycerol ether is used as an emulsifier to improve the emulsification performance and uniformity of the latex paint. The film-forming agent must be well-mixable with the photosensitive substance and have the same solubility, including water solubility, alkali solubility, and organic solvent solubility. The leveling agent improves the mechanical and physicochemical stability of the alkali-resistant primer. The thickener further increases the viscosity of the nano-latex paint surface, preventing it from... During storage, precipitation occurs, which promotes the formation of a smooth, even, and uniform film during the drying process of latex paint. Hydroxypropyl methylcellulose, as a thickener, can increase the viscosity of the system, keeping it in a uniform and stable suspension or emulsion state, or forming a gel. It can increase the surface viscosity of latex paint, change its fluidity, and also has an emulsifying effect. Defoamers are substances that can reduce the surface tension of water, solutions, suspensions, etc., prevent foam formation, or reduce or eliminate existing foam, thus improving the smoothness of the coating. Sodium bicarbonate, as a pH adjuster, adjusts the overall pH of the latex paint. Multifunctional antibacterial agents are used to improve the antibacterial and antifungal properties of latex paint, while also improving other comprehensive properties.

[0007] The defoamer is one or more of the following: polyether defoamer, silicone oil defoamer, higher alcohol defoamer, and mineral oil.

[0008] The leveling agent is at least one of polyurethane leveling agents and silicone leveling agents.

[0009] The film-forming agent is selected from one or more of propylene glycol methyl ether acetate, dodecyl alcohol ester, diethylene glycol butyl ether, propylene glycol butyl ether, and hexanediol butyl ether acetate.

[0010] The preparation method of the functionalized bentonite is as follows:

[0011] Add 70-100 parts by weight of bentonite to 200-400 parts by weight of water and ultrasonically disperse for 5-10 minutes; then add 5-10 parts by weight of didecyldimethylammonium chloride and 3-5 parts by weight of imidazolidinyl urea, stir at 60-65℃ and 200-500 rpm for 3-6 hours, filter, and vacuum dry at 70-80℃ for 8-10 hours to obtain pretreated bentonite; take 30-60 parts by weight of pretreated bentonite, 5-10 parts by weight of silica powder, 1-2 parts by weight of sodium tripolyphosphate, and 1-3 parts by weight of tris(dimethylsiloxane)silane and add them to a ball mill for 2-4 hours at a ball milling rate of 150-350 rpm to obtain the functionalized bentonite.

[0012] The multifunctional antibacterial agent is at least one of porous chitosan microspheres, modified porous chitosan microspheres, and chitosan complex.

[0013] Preferably, the multifunctional antibacterial agent is porous chitosan microspheres, and the preparation method of the porous chitosan microspheres is as follows: 5-12 parts by weight of chitosan and 200-350 parts by weight of 1-5 wt% hydrochloric acid aqueous solution are mixed and ultrasonicated at 25-40℃, ultrasonic frequency 20-40kHz, and ultrasonic power 100-300W for 20-40 min; 30-60 parts by weight of liquid paraffin and 0.5-2 parts by weight of polyethylene glycol are added, and the mixture is stirred at 800-1100 rpm for 10-30 min; the mixture is filtered, washed with anhydrous ethanol, and vacuum dried at 60-80℃ for 8-12 h to obtain porous chitosan microspheres;

[0014] Chitosan is a readily available natural biomolecule with numerous excellent properties, including antibacterial, hygroscopic, biocompatible, film-forming, and flocculating properties. It is widely used in food, pharmaceuticals, papermaking, coatings, wastewater treatment, and other biological and chemical fields. However, chitosan has poor solubility and adsorption properties, exhibiting poor solubility in water and common organic solvents, which significantly limits its application. Nevertheless, the chitosan molecular chain contains various functional groups, allowing for chemical modification of its repeating units to introduce different groups and obtain derivative materials with improved solubility. Furthermore, the introduction of different substituents gives chitosan derivative materials diverse functions.

[0015] Specifically, this invention provides a modified porous chitosan microsphere that not only has strong antibacterial properties but also possesses certain adsorption functions. The modification involves introducing malonic anhydride and hydroxypropyltrimethylammonium chloride into the chitosan microspheres. Malonic anhydride has both hydrophilic and hydrophobic groups, which can improve the compatibility of the chitosan microspheres. Hydroxypropyltrimethylammonium chloride chitosan is a type of quaternized chitosan derivative. The introduction of quaternary ammonium groups allows chitosan to overcome the defect of only dissolving under acidic conditions, improving its water solubility and providing better antibacterial properties.

[0016] Furthermore, the multifunctional antibacterial agent is modified porous chitosan microspheres. The preparation method of the modified porous chitosan microspheres is as follows: 5-12 parts by weight of chitosan and 200-350 parts by weight of 1-5 wt% hydrochloric acid aqueous solution are mixed and ultrasonicated for 20-40 min at 25-40℃, ultrasonic frequency 20-40 kHz, and ultrasonic power 100-300 W; 30-60 parts by weight of liquid paraffin and 0.5-2 parts by weight of polyethylene glycol are added and stirred at 800-1100 rpm for 10-30 min; then 3-15 parts by weight of modifier are added and stirred at 35-60℃ and 300-500 rpm for 3-5 h; the mixture is filtered, washed with anhydrous ethanol, and vacuum dried at 60-80℃ for 8-12 h to obtain modified porous chitosan microspheres.

[0017] Nano-titanium dioxide, due to its nano-particle size, has a large specific surface area, excellent light absorption, and significant photocatalytic performance. It also possesses antibacterial, bactericidal, and air-purifying properties, making it widely used in cosmetics, functional fibers, plastics, coatings, and paints. Under sunlight or ultraviolet light, nano-titanium dioxide activates TiO2, generating highly catalytically active free radicals with strong photo-oxidation and reduction capabilities. It can catalyze and photodegrade various organic substances such as formaldehyde and some inorganic substances adhering to object surfaces. However, nano-titanium dioxide powder is prone to agglomeration and difficult to disperse in latex paint. Nano-titanium dioxide hydrosol, on the other hand, offers advantages such as high dispersion of active substances, small particle size, high specific surface area, strong adhesion to the matrix, high catalytic activity, and ease of application. Furthermore, modified porous chitosan microspheres exhibit strong antibacterial properties. Combining these two components in latex paint provides multiple functions, including antibacterial properties, formaldehyde degradation, and improved mechanical properties, thus enhancing the overall performance of the latex paint.

[0018] This invention employs a C3N4 / TiO2 composite as a formaldehyde degradation catalyst, which has the ability to catalyze the degradation of formaldehyde under natural light conditions. By crosslinking the C3N4 / TiO2 composite with modified porous chitosan microspheres, the two work together synergistically. Formaldehyde is adsorbed by the amino groups in the chitosan molecules, and the adsorbed formaldehyde is further catalyzed and degraded by the C3N4 / TiO2 nanocomposite catalyst, thereby achieving efficient and long-lasting formaldehyde removal. At the same time, both titanium dioxide and chitosan have bactericidal and antibacterial effects, and the antibacterial effect is further enhanced. Together, they improve the antibacterial performance and the formaldehyde degradation effect.

[0019] Furthermore, the multifunctional antibacterial agent is a chitosan complex, and the preparation method of the chitosan complex is as follows:

[0020] (1) Mix 20-40 parts by weight of di(2-hydroxypropionic acid) diammonium hydroxide titanium, 2-8 parts by weight of acetylacetone, 2-6 parts by weight of polyethylene glycol, and 120-200 parts by weight of anhydrous ethanol, stir at 400-600 rpm for 10-30 min, adjust the pH to 2.5-4 with 1-3 mol / L hydrochloric acid, and react at 50-70℃ and 500-700 rpm for 1-4 h to obtain titanium dioxide colloid;

[0021] (2) Mix 10-30 parts by weight of dicyandiamine and all of the above titanium dioxide colloid, place in a muffle furnace, heat to 450-600℃ at a heating rate of 3-7℃ / min, calcine in a nitrogen atmosphere for 4-8 hours, cool naturally, grind, and pass through a 700-1000 mesh sieve to obtain C3N4 / TiO2 composite.

[0022] (3) Mix 5-12 parts by weight of chitosan and 200-350 parts by weight of 1-5 wt% hydrochloric acid aqueous solution, and sonicate at 25-40℃, ultrasonic frequency 20-40kHz, and ultrasonic power 100-300W for 20-40 min; add 30-60 parts by weight of liquid paraffin and 0.5-2 parts by weight of polyethylene glycol, and stir at 800-1100rpm for 10-30 min; then add 3-15 parts by weight of modifier, and stir at 35-60℃ and 300-500rpm for 3-5 h, filter, wash with anhydrous ethanol, and vacuum dry at 60-80℃ for 8-16 h to obtain modified porous chitosan microspheres;

[0023] (4) Take 3-8 parts by weight of modified porous chitosan microspheres, 5-12 parts by weight of C3N4 / TiO2 composite and 40-100 parts by weight of water and mix them. Sonicate at an ultrasonic frequency of 30-60kHz and an ultrasonic power of 200-400W for 20-40min. Add 2-5 parts by weight of glutaraldehyde and adjust the pH to 9-11 with 1-4mol / L potassium hydroxide aqueous solution. React at 60-80℃ and 100-300rpm for 2-5h. Filter, wash with anhydrous ethanol, and vacuum dry at 60-80℃ for 8-16h to obtain chitosan composite.

[0024] The modifier is malonic anhydride and / or hydroxypropyltrimethylammonium chloride; preferably, the modifier is composed of malonic anhydride and hydroxypropyltrimethylammonium chloride in a mass ratio of (1-3):(1-5).

[0025] The preparation method of the aforementioned antibacterial and environmentally friendly latex paint includes the following steps:

[0026] S1. Weigh out each raw material;

[0027] S2. Mix water, acrylic emulsion, stearamide, polyoxypropylene polyoxyethylene glycerol ether and hydroxypropyl methylcellulose, and stir at 400-800 rpm for 30-60 min to obtain a slurry;

[0028] S3. Mix polyacrylamide, film-forming agent, bentonite or functionalized bentonite, calcium carbonate, leveling agent, defoamer, sodium bicarbonate, and multifunctional antibacterial agent, add to the above slurry, and stir at 800-1200 rpm for 40-90 minutes to obtain antibacterial and environmentally friendly latex paint.

[0029] The beneficial effects of this invention are as follows: The antibacterial and environmentally friendly latex paint of this invention not only has good antibacterial, antifungal, waterproof, and stain-resistant properties, but also can adsorb and degrade harmful gases such as formaldehyde in the surrounding environment. It is green and environmentally friendly, and the preparation method is simple. The chitosan complex used in this invention simultaneously contains a C3N4 / TiO2 complex and a modified porous chitosan microsphere cross-linked compound, which has good antibacterial properties. The addition of the modifier introduces quaternary ammonium salts to improve antibacterial properties. In addition, the introduction of carboxyl groups in the modifier improves the compatibility and stability of the filler in the latex paint. The porous chitosan structure and the amino and carboxyl groups modified on the surface can adsorb harmful gases such as formaldehyde, which are then catalytically degraded by the C3N4 / TiO2 complex, continuously purifying the surrounding environment. Detailed Implementation

[0030] The invention will now be described in further detail with reference to specific embodiments, but it should not be construed as limiting the scope of the invention to the following embodiments.

[0031] Description of some raw materials in this application:

[0032] The acrylic acid emulsion was purchased from Jining Sanshi Biotechnology Co., Ltd., with a content of ≥55% and a viscosity of 3800 mPa.s.

[0033] The bentonite was purchased from Hebei Jiegui Mineral Products Co., Ltd., with a specification of 1250 mesh.

[0034] The silica powder was purchased from Shanghai Jiadeer Chemical Technology Co., Ltd., specification: 200 mesh.

[0035] Calcium carbonate was purchased from Lingshou County Ningbo Mineral Products Co., Ltd., mesh size: 1250, item number: tsg-2-21.

[0036] The polyacrylamide was purchased from Henan Songlan Environmental Protection Technology Co., Ltd., model: SL-201, molecular weight: 10 million g / mol.

[0037] The polyoxypropylene polyoxyethylene glycerol ether was purchased from Nantong Arches Chemical Co., Ltd., model: GPE-3000.

[0038] Polydimethylsiloxane was purchased from Shenzhen Jipeng Silicon Fluorine Materials Co., Ltd., model: 209, hydroxyl content: 10%.

[0039] Chitosan was purchased from West Asia Chemical Technology (Shandong) Co., Ltd., with a viscosity of 200 mPa·s.

[0040] Di(2-hydroxypropionic acid) diammonium hydroxide titanium, CAS: 65104-06-5.

[0041] Dicyandiamine, CAS: 461-58-5.

[0042] Polyethylene glycol was purchased from Guangzhou Yehusheng Trading Co., Ltd., model: PEG4000.

[0043] The liquid paraffin was purchased from Nantong Runfeng Petrochemical Co., Ltd.

[0044] Example 1

[0045] The antibacterial and environmentally friendly latex paint comprises the following raw materials in parts by weight: 220 parts acrylic emulsion, 40 parts bentonite, 70 parts calcium carbonate, 4 parts polyacrylamide, 15 parts polyoxypropylene polyoxyethylene glycerol ether, 1 part stearamide, 6 parts diethylene glycol butyl ether, 2 parts polydimethylsiloxane, 4 parts hydroxypropyl methylcellulose, 6 parts dimethylsiloxane, 0.5 parts sodium bicarbonate, 200 parts water, and 10 parts multifunctional antibacterial agent.

[0046] The multifunctional antibacterial agent is porous chitosan microspheres. The preparation method of the porous chitosan microspheres is as follows: 10 parts by weight of chitosan and 300 parts by weight of 2wt% hydrochloric acid aqueous solution are mixed and ultrasonicated at 30℃, ultrasonic frequency 30kHz, and ultrasonic power 200W for 30min; 50 parts by weight of liquid paraffin and 1 part by weight of polyethylene glycol are added and stirred at 1000rpm for 20min; the mixture is filtered, washed with anhydrous ethanol, and vacuum dried at 70℃ for 10h to obtain porous chitosan microspheres.

[0047] The preparation method of antibacterial and environmentally friendly latex paint includes the following steps:

[0048] S1. Weigh out each raw material;

[0049] S2. Mix water, acrylic emulsion, stearamide, polyoxypropylene polyoxyethylene glycerol ether and hydroxypropyl methylcellulose, and stir at 600 rpm for 40 min to obtain a slurry;

[0050] S3. Mix polyacrylamide, dimethylsiloxane, bentonite, calcium carbonate, polydimethylsiloxane, diethylene glycol butyl ether, sodium bicarbonate, and multifunctional antibacterial agent, add them to the above slurry, and stir at 1000 rpm for 60 minutes to obtain antibacterial and environmentally friendly latex paint.

[0051] Comparative Example 1

[0052] The antibacterial and environmentally friendly latex paint comprises the following raw materials in parts by weight: 220 parts acrylic emulsion, 40 parts bentonite, 70 parts calcium carbonate, 4 parts polyacrylamide, 15 parts polyoxypropylene polyoxyethylene glycerol ether, 1 part stearamide, 6 parts diethylene glycol butyl ether, 2 parts polydimethylsiloxane, 4 parts hydroxypropyl methylcellulose, 6 parts dimethylsiloxane, 0.5 parts sodium bicarbonate, 200 parts water, and 10 parts multifunctional antibacterial agent.

[0053] The multifunctional antibacterial agent is chitosan.

[0054] The preparation method of antibacterial and environmentally friendly latex paint includes the following steps:

[0055] S1. Weigh out each raw material;

[0056] S2. Mix water, acrylic emulsion, stearamide, polyoxypropylene polyoxyethylene glycerol ether and hydroxypropyl methylcellulose, and stir at 600 rpm for 40 min to obtain a slurry;

[0057] S3. Mix polyacrylamide, dimethylsiloxane, bentonite, calcium carbonate, polydimethylsiloxane, diethylene glycol butyl ether, sodium bicarbonate, and multifunctional antibacterial agent, add them to the above slurry, and stir at 1000 rpm for 60 minutes to obtain antibacterial and environmentally friendly latex paint.

[0058] Example 2

[0059] The antibacterial and environmentally friendly latex paint comprises the following raw materials in parts by weight: 220 parts acrylic emulsion, 40 parts bentonite, 70 parts calcium carbonate, 4 parts polyacrylamide, 15 parts polyoxypropylene polyoxyethylene glycerol ether, 1 part stearamide, 6 parts diethylene glycol butyl ether, 2 parts polydimethylsiloxane, 4 parts hydroxypropyl methylcellulose, 6 parts dimethylsiloxane, 0.5 parts sodium bicarbonate, 200 parts water, and 10 parts multifunctional antibacterial agent.

[0060] The multifunctional antibacterial agent is modified porous chitosan microspheres. The preparation method of the modified porous chitosan microspheres is as follows: 10 parts by weight of chitosan and 300 parts by weight of a 2 wt% hydrochloric acid aqueous solution are mixed and ultrasonicated at 30°C, 30 kHz ultrasonic frequency, and 200 W ultrasonic power for 30 min; 50 parts by weight of liquid paraffin and 1 part by weight of polyethylene glycol are added, and the mixture is stirred at 1000 rpm for 20 min; then 10 parts by weight of the modifier are added, and the mixture is stirred at 50°C and 400 rpm for 4 h; the mixture is filtered, washed with anhydrous ethanol, and vacuum dried at 70°C for 10 h to obtain modified porous chitosan microspheres. The modifier is hydroxypropyltrimethylammonium chloride.

[0061] The preparation method of antibacterial and environmentally friendly latex paint includes the following steps:

[0062] S1. Weigh out each raw material;

[0063] S2. Mix water, acrylic emulsion, stearamide, polyoxypropylene polyoxyethylene glycerol ether and hydroxypropyl methylcellulose, and stir at 600 rpm for 40 min to obtain a slurry;

[0064] S3. Mix polyacrylamide, dimethylsiloxane, bentonite, calcium carbonate, polydimethylsiloxane, diethylene glycol butyl ether, sodium bicarbonate, and multifunctional antibacterial agent, add them to the above slurry, and stir at 1000 rpm for 60 minutes to obtain antibacterial and environmentally friendly latex paint.

[0065] Example 3

[0066] The antibacterial and environmentally friendly latex paint comprises the following raw materials in parts by weight: 220 parts acrylic emulsion, 40 parts bentonite, 70 parts calcium carbonate, 4 parts polyacrylamide, 15 parts polyoxypropylene polyoxyethylene glycerol ether, 1 part stearamide, 6 parts diethylene glycol butyl ether, 2 parts polydimethylsiloxane, 4 parts hydroxypropyl methylcellulose, 6 parts dimethylsiloxane, 0.5 parts sodium bicarbonate, 200 parts water, and 10 parts multifunctional antibacterial agent.

[0067] The multifunctional antibacterial agent is a chitosan complex, and the preparation method of the chitosan complex is as follows:

[0068] (1) Mix 30 parts by weight of di(2-hydroxypropionic acid) diammonium hydroxide titanium, 3 parts by weight of acetylacetone, 3 parts by weight of polyethylene glycol and 160 parts by weight of anhydrous ethanol, stir at 500 rpm for 20 min, adjust the pH to 3 with 2 mol / L hydrochloric acid, and react at 60℃ and 600 rpm for 2 h to obtain titanium dioxide colloid.

[0069] (2) Mix 20 parts by weight of dicyandiamine and all of the above titanium dioxide colloid, place in a muffle furnace, heat to 550°C at a heating rate of 5°C / min, calcine in a nitrogen atmosphere for 6 hours, cool naturally, grind, and pass through an 800-mesh sieve to obtain the C3N4 / TiO2 composite.

[0070] (3) Mix 10 parts by weight of chitosan and 300 parts by weight of 2wt% hydrochloric acid aqueous solution, and sonicate at 30℃, ultrasonic frequency 30kHz and ultrasonic power 200W for 30min; add 50 parts by weight of liquid paraffin and 1 part by weight of polyethylene glycol, and stir at 1000rpm for 20min; then add 10 parts by weight of modifier, stir at 50℃ and 400rpm for 4h, filter, wash with anhydrous ethanol, and vacuum dry at 70℃ for 10h to obtain modified porous chitosan microspheres;

[0071] (4) Take 5 parts by weight of modified porous chitosan microspheres, 10 parts by weight of C3N4 / TiO2 composite and 50 parts by weight of water and mix them. Sonicate for 30 min at an ultrasonic frequency of 40 kHz and an ultrasonic power of 300 W. Add 3 parts by weight of glutaraldehyde and adjust the pH to 10 with 2 mol / L potassium hydroxide aqueous solution. React at 70℃ and 200 rpm for 3 h. Filter, wash with anhydrous ethanol, and vacuum dry at 70℃ for 10 h to obtain chitosan composite.

[0072] The modifier is hydroxypropyltrimethylammonium chloride.

[0073] The preparation method of antibacterial and environmentally friendly latex paint includes the following steps:

[0074] S1. Weigh out each raw material;

[0075] S2. Mix water, acrylic emulsion, stearamide, polyoxypropylene polyoxyethylene glycerol ether and hydroxypropyl methylcellulose, and stir at 600 rpm for 40 min to obtain a slurry;

[0076] S3. Mix polyacrylamide, dimethylsiloxane, bentonite, calcium carbonate, polydimethylsiloxane, diethylene glycol butyl ether, sodium bicarbonate, and multifunctional antibacterial agent, add them to the above slurry, and stir at 1000 rpm for 60 minutes to obtain antibacterial and environmentally friendly latex paint.

[0077] Comparative Example 2

[0078] This is essentially the same as Example 3, except that the preparation method of the chitosan complex is as follows:

[0079] (1) Mix 30 parts by weight of di(2-hydroxypropionic acid) diammonium hydroxide titanium, 3 parts by weight of acetylacetone, 3 parts by weight of polyethylene glycol and 160 parts by weight of anhydrous ethanol, stir at 500 rpm for 20 min, adjust the pH to 3 with 2 mol / L hydrochloric acid, and react at 60℃ and 600 rpm for 2 h to obtain titanium dioxide colloid.

[0080] (2) Mix 20 parts by weight of dicyandiamine and all of the above titanium dioxide colloid, place in a muffle furnace, heat to 550°C at a heating rate of 5°C / min, calcine in a nitrogen atmosphere for 6 hours, cool naturally, grind, and pass through an 800-mesh sieve to obtain the C3N4 / TiO2 composite.

[0081] (3) Take 5 parts by weight of chitosan, 10 parts by weight of C3N4 / TiO2 complex and 50 parts by weight of water and mix them. Sonicate at an ultrasonic frequency of 40kHz and an ultrasonic power of 300W for 30min. Add 3 parts by weight of glutaraldehyde and adjust the pH to 10 with 2mol / L potassium hydroxide aqueous solution. React at 70℃ and 200rpm for 3h. Filter, wash with anhydrous ethanol, and vacuum dry at 70℃ for 10h to obtain chitosan complex.

[0082] Example 4

[0083] This is essentially the same as Example 3, except that the preparation method of the chitosan complex is as follows:

[0084] (1) Mix 30 parts by weight of di(2-hydroxypropionic acid) diammonium hydroxide titanium, 3 parts by weight of acetylacetone, 3 parts by weight of polyethylene glycol and 160 parts by weight of anhydrous ethanol, stir at 500 rpm for 20 min, adjust the pH to 3 with 2 mol / L hydrochloric acid, and react at 60℃ and 600 rpm for 2 h to obtain titanium dioxide colloid.

[0085] (2) Mix 20 parts by weight of dicyandiamine and all of the above titanium dioxide colloid, place in a muffle furnace, heat to 550°C at a heating rate of 5°C / min, calcine in a nitrogen atmosphere for 6 hours, cool naturally, grind, and pass through an 800-mesh sieve to obtain the C3N4 / TiO2 composite.

[0086] (3) Mix 10 parts by weight of chitosan and 300 parts by weight of 2wt% hydrochloric acid aqueous solution, and sonicate at 30℃, ultrasonic frequency 30kHz and ultrasonic power 200W for 30min; add 50 parts by weight of liquid paraffin and 1 part by weight of polyethylene glycol, and stir at 1000rpm for 20min; then add 10 parts by weight of modifier, stir at 50℃ and 400rpm for 4h, filter, wash with anhydrous ethanol, and vacuum dry at 70℃ for 10h to obtain modified porous chitosan microspheres;

[0087] (4) Take 5 parts by weight of modified porous chitosan microspheres, 10 parts by weight of C3N4 / TiO2 composite and 50 parts by weight of water and mix them. Sonicate for 30 min at an ultrasonic frequency of 40 kHz and an ultrasonic power of 300 W. Add 3 parts by weight of glutaraldehyde and adjust the pH to 10 with 2 mol / L potassium hydroxide aqueous solution. React at 70℃ and 200 rpm for 3 h. Filter, wash with anhydrous ethanol, and vacuum dry at 70℃ for 10 h to obtain chitosan composite.

[0088] The modifier is malonic anhydride.

[0089] Example 5

[0090] This is essentially the same as Example 3, except that the preparation method of the chitosan complex is as follows:

[0091] (1) Mix 30 parts by weight of di(2-hydroxypropionic acid) diammonium hydroxide titanium, 3 parts by weight of acetylacetone, 3 parts by weight of polyethylene glycol and 160 parts by weight of anhydrous ethanol, stir at 500 rpm for 20 min, adjust the pH to 3 with 2 mol / L hydrochloric acid, and react at 60℃ and 600 rpm for 2 h to obtain titanium dioxide colloid.

[0092] (2) Mix 20 parts by weight of dicyandiamine and all of the above titanium dioxide colloid, place in a muffle furnace, heat to 550°C at a heating rate of 5°C / min, calcine in a nitrogen atmosphere for 6 hours, cool naturally, grind, and pass through an 800-mesh sieve to obtain the C3N4 / TiO2 composite.

[0093] (3) Mix 10 parts by weight of chitosan and 300 parts by weight of 2wt% hydrochloric acid aqueous solution, and sonicate at 30℃, ultrasonic frequency 30kHz and ultrasonic power 200W for 30min; add 50 parts by weight of liquid paraffin and 1 part by weight of polyethylene glycol, and stir at 1000rpm for 20min; then add 10 parts by weight of modifier, stir at 50℃ and 400rpm for 4h, filter, wash with anhydrous ethanol, and vacuum dry at 70℃ for 10h to obtain modified porous chitosan microspheres;

[0094] (4) Take 5 parts by weight of modified porous chitosan microspheres, 10 parts by weight of C3N4 / TiO2 composite and 50 parts by weight of water and mix them. Sonicate for 30 min at an ultrasonic frequency of 40 kHz and an ultrasonic power of 300 W. Add 3 parts by weight of glutaraldehyde and adjust the pH to 10 with 2 mol / L potassium hydroxide aqueous solution. React at 70℃ and 200 rpm for 3 h. Filter, wash with anhydrous ethanol, and vacuum dry at 70℃ for 10 h to obtain chitosan composite.

[0095] The modifier is composed of malonic anhydride and hydroxypropyltrimethylammonium chloride in a mass ratio of 2:3.

[0096] Example 6

[0097] The antibacterial and environmentally friendly latex paint comprises the following raw materials in parts by weight: 220 parts acrylic emulsion, 40 parts functionalized bentonite, 70 parts calcium carbonate, 4 parts polyacrylamide, 15 parts polyoxypropylene polyoxyethylene glycerol ether, 1 part stearamide, 6 parts diethylene glycol butyl ether, 2 parts polydimethylsiloxane, 4 parts hydroxypropyl methylcellulose, 6 parts dimethylsiloxane, 0.5 parts sodium bicarbonate, 200 parts water, and 10 parts multifunctional antibacterial agent.

[0098] The preparation method of the functionalized bentonite is as follows:

[0099] Take 50 parts by weight of bentonite, 8 parts by weight of silica powder, 1.5 parts by weight of sodium tripolyphosphate, and 2 parts by weight of tris(dimethylsiloxane)silane and add them to a ball mill for 2.5 hours. The ball milling rate is 200 rpm to obtain the functionalized bentonite.

[0100] The multifunctional antibacterial agent is a chitosan complex, and the preparation method of the chitosan complex is as follows:

[0101] (1) Mix 30 parts by weight of di(2-hydroxypropionic acid) diammonium hydroxide titanium, 3 parts by weight of acetylacetone, 3 parts by weight of polyethylene glycol and 160 parts by weight of anhydrous ethanol, stir at 500 rpm for 20 min, adjust the pH to 3 with 2 mol / L hydrochloric acid, and react at 60℃ and 600 rpm for 2 h to obtain titanium dioxide colloid.

[0102] (2) Mix 20 parts by weight of dicyandiamine and all of the above titanium dioxide colloid, place in a muffle furnace, heat to 550°C at a heating rate of 5°C / min, calcine in a nitrogen atmosphere for 6 hours, cool naturally, grind, and pass through an 800-mesh sieve to obtain the C3N4 / TiO2 composite.

[0103] (3) Mix 10 parts by weight of chitosan and 300 parts by weight of 2wt% hydrochloric acid aqueous solution, and sonicate at 30℃, ultrasonic frequency 30kHz and ultrasonic power 200W for 30min; add 50 parts by weight of liquid paraffin and 1 part by weight of polyethylene glycol, and stir at 1000rpm for 20min; then add 10 parts by weight of modifier, stir at 50℃ and 400rpm for 4h, filter, wash with anhydrous ethanol, and vacuum dry at 70℃ for 10h to obtain modified porous chitosan microspheres;

[0104] (4) Take 5 parts by weight of modified porous chitosan microspheres, 10 parts by weight of C3N4 / TiO2 composite and 50 parts by weight of water and mix them. Sonicate for 30 min at an ultrasonic frequency of 40 kHz and an ultrasonic power of 300 W. Add 3 parts by weight of glutaraldehyde and adjust the pH to 10 with 2 mol / L potassium hydroxide aqueous solution. React at 70℃ and 200 rpm for 3 h. Filter, wash with anhydrous ethanol, and vacuum dry at 70℃ for 10 h to obtain chitosan composite.

[0105] The modifier is composed of malonic anhydride and hydroxypropyltrimethylammonium chloride in a mass ratio of 2:3.

[0106] The preparation method of antibacterial and environmentally friendly latex paint includes the following steps:

[0107] S1. Weigh out each raw material;

[0108] S2. Mix water, acrylic emulsion, stearamide, polyoxypropylene polyoxyethylene glycerol ether and hydroxypropyl methylcellulose, and stir at 600 rpm for 40 min to obtain a slurry;

[0109] S3. Polyacrylamide, dimethylsiloxane, functionalized bentonite, calcium carbonate, polydimethylsiloxane, diethylene glycol butyl ether, sodium bicarbonate, and a multifunctional antibacterial agent are mixed and added to the above slurry. The mixture is stirred at 1000 rpm for 60 minutes to obtain an antibacterial and environmentally friendly latex paint. The antibacterial and environmentally friendly latex paint prepared in Example 6 is applied to a sample plate to form a 50 μm thick coating. The contact angle of the coating is tested using a contact angle tester (the larger the contact angle, the stronger the waterproof and stain-resistant properties). The contact angle is 138°.

[0110] Example 7

[0111] The antibacterial and environmentally friendly latex paint comprises the following raw materials in parts by weight: 220 parts acrylic emulsion, 40 parts functionalized bentonite, 70 parts calcium carbonate, 4 parts polyacrylamide, 15 parts polyoxypropylene polyoxyethylene glycerol ether, 1 part stearamide, 6 parts diethylene glycol butyl ether, 2 parts polydimethylsiloxane, 4 parts hydroxypropyl methylcellulose, 6 parts dimethylsiloxane, 0.5 parts sodium bicarbonate, 200 parts water, and 10 parts multifunctional antibacterial agent.

[0112] The preparation method of the functionalized bentonite is as follows:

[0113] 80 parts by weight of bentonite were added to 300 parts by weight of water and ultrasonically dispersed for 6 min; then 7.5 parts by weight of didecyldimethylammonium chloride and 3.5 parts by weight of imidazolidinyl urea were added, and the mixture was stirred at 63℃ and 300 rpm for 5 h, filtered, and vacuum dried at 70℃ for 10 h to obtain pretreated bentonite; 50 parts by weight of pretreated bentonite, 8 parts by weight of silica powder, 1.5 parts by weight of sodium tripolyphosphate, and 2 parts by weight of tris(dimethylsiloxane)silane were added to a ball mill and treated for 2.5 h at a ball milling rate of 200 rpm to obtain the functionalized bentonite.

[0114] The multifunctional antibacterial agent is a chitosan complex, and the preparation method of the chitosan complex is as follows:

[0115] (1) Mix 30 parts by weight of di(2-hydroxypropionic acid) diammonium hydroxide titanium, 3 parts by weight of acetylacetone, 3 parts by weight of polyethylene glycol and 160 parts by weight of anhydrous ethanol, stir at 500 rpm for 20 min, adjust the pH to 3 with 2 mol / L hydrochloric acid, and react at 60℃ and 600 rpm for 2 h to obtain titanium dioxide colloid.

[0116] (2) Mix 20 parts by weight of dicyandiamine and all of the above titanium dioxide colloid, place in a muffle furnace, heat to 550°C at a heating rate of 5°C / min, calcine in a nitrogen atmosphere for 6 hours, cool naturally, grind, and pass through an 800-mesh sieve to obtain the C3N4 / TiO2 composite.

[0117] (3) Mix 10 parts by weight of chitosan and 300 parts by weight of 2wt% hydrochloric acid aqueous solution, and sonicate at 30℃, ultrasonic frequency 30kHz and ultrasonic power 200W for 30min; add 50 parts by weight of liquid paraffin and 1 part by weight of polyethylene glycol, and stir at 1000rpm for 20min; then add 10 parts by weight of modifier, stir at 50℃ and 400rpm for 4h, filter, wash with anhydrous ethanol, and vacuum dry at 70℃ for 10h to obtain modified porous chitosan microspheres;

[0118] (4) Take 5 parts by weight of modified porous chitosan microspheres, 10 parts by weight of C3N4 / TiO2 composite and 50 parts by weight of water and mix them. Sonicate for 30 min at an ultrasonic frequency of 40 kHz and an ultrasonic power of 300 W. Add 3 parts by weight of glutaraldehyde and adjust the pH to 10 with 2 mol / L potassium hydroxide aqueous solution. React at 70℃ and 200 rpm for 3 h. Filter, wash with anhydrous ethanol, and vacuum dry at 70℃ for 10 h to obtain chitosan composite.

[0119] The modifier is composed of malonic anhydride and hydroxypropyltrimethylammonium chloride in a mass ratio of 2:3.

[0120] The preparation method of antibacterial and environmentally friendly latex paint includes the following steps:

[0121] S1. Weigh out each raw material;

[0122] S2. Mix water, acrylic emulsion, stearamide, polyoxypropylene polyoxyethylene glycerol ether and hydroxypropyl methylcellulose, and stir at 600 rpm for 40 min to obtain a slurry;

[0123] S3. Polyacrylamide, dimethylsiloxane, functionalized bentonite, calcium carbonate, polydimethylsiloxane, diethylene glycol butyl ether, sodium bicarbonate, and a multifunctional antibacterial agent are mixed and added to the above slurry. The mixture is stirred at 1000 rpm for 60 minutes to obtain an antibacterial and environmentally friendly latex paint. The antibacterial and environmentally friendly latex paint prepared in Example 7 is applied to a sample plate to form a 50 μm thick coating. The contact angle of the coating is tested using a contact angle tester (the larger the contact angle, the stronger the waterproof and stain-resistant properties). The contact angle is 146°.

[0124] Test Example 1

[0125] Antibacterial performance test: Antibacterial test was conducted in accordance with the national standard GB / T21866-2008 "Antibacterial Coatings (Films) Antibacterial Performance Test Method and Antibacterial Effect". The antibacterial and environmentally friendly latex paints prepared in Examples 1-5 and Comparative Examples 1-2 were applied to cement boards respectively. The total wet film thickness of the coating was 90μm. The coating was prepared according to the requirements of GB / T1727. The coating was applied in two coats. After the first coat was surface dry, the second coat was applied. The cement board was dried for 7 days under the conditions specified in GB / T 9278. The coated cement board was cut into 50mm×50mm test boards. The test boards were sterilized with ultraviolet sterilization lamp for 5 minutes before the experiment.

[0126] Antibacterial test procedure: Staphylococcus aureus (AS1.89) and Escherichia coli (AS1.90) were used as experimental bacteria. They were dropped onto a test plate coated with antibacterial environmentally friendly latex paint and incubated for 24 hours at 37℃ and relative humidity >90%. The incubated samples were then removed, and 20 ml of washing buffer was added to each sample for repeated washing. The washing buffer was then inoculated into nutrient agar medium and incubated at 37℃ for 28 hours. Viable bacteria were counted, and the average value was taken from three tests.

[0127] Antibacterial durability test: A 30W UV lamp with a wavelength of 253.7nm was used. The test panel coated with antibacterial and environmentally friendly latex paint was placed 1m away from the UV lamp and irradiated for 100 hours. After treatment, the antibacterial performance was tested according to the standard. Three tests were conducted on average, and the average value was taken.

[0128] Table 1. Antibacterial performance test results

[0129]

[0130] As shown in Table 1 above, the antibacterial and environmentally friendly latex paint prepared by this invention has excellent antibacterial properties and durability. The modified porous chitosan microspheres not only increase the binding performance and compatibility between chitosan and latex paint, allowing it to be uniformly dispersed in the latex paint, but the addition of propyltrimethylammonium chloride further enhances the antibacterial properties. The addition of malonic anhydride improves the stability of chitosan in the latex paint, thus achieving a long-lasting antibacterial effect. Furthermore, nano-titanium dioxide also has antibacterial, bactericidal, and air-purifying effects; its addition further enhances the antibacterial properties. The two components work synergistically to improve the antibacterial performance of the latex paint.

[0131] The antibacterial and environmentally friendly latex paint prepared by this invention not only has strong antibacterial properties but also possesses a certain adsorption function. In Example 5, malonic anhydride and hydroxypropyltrimethylammonium chloride were introduced into the chitosan microspheres through modification. Malonic anhydride has both hydrophilic and hydrophobic groups, which can improve the compatibility of chitosan microspheres. Hydroxypropyltrimethylammonium chloride chitosan is one of the quaternized derivatives of chitosan. The introduction of quaternary ammonium groups enables chitosan to overcome the defect that it can only dissolve under acidic conditions, improves water solubility, and has better antibacterial properties. The two work synergistically to improve the antibacterial performance of the antibacterial and environmentally friendly latex paint.

[0132] Test Example 2

[0133] Formaldehyde degradation performance test: The test was conducted in accordance with the national standard JC / T 1074-2008 "Purification performance of indoor air purification functional coating materials". The antibacterial and environmentally friendly latex paints of Examples 2-5 and Comparative Example 2 were evenly sprayed on a 500mm×500mm glass plate with a thickness of 5mm. The glass plate was dried at 20℃ and 50% relative humidity for 24 hours before the test. The test was conducted 3 times on average and the average value was taken.

[0134] Table 2 Formaldehyde degradation performance test results

[0135]

[0136] As shown in Table 2 above, the antibacterial and environmentally friendly latex paint prepared by this invention has air purification properties. By using a C3N4 / TiO2 composite as a formaldehyde degradation catalyst, this catalyst has the ability to catalyze the degradation of formaldehyde under natural light conditions. By crosslinking the C3N4 / TiO2 composite with modified porous chitosan microspheres, the two work together synergistically. Formaldehyde is adsorbed by the amino groups in the chitosan molecules, and the adsorbed formaldehyde is further catalyzed and degraded by the C3N4 / TiO2 nanocomposite catalyst. The porous structure of the modified porous chitosan microspheres can adsorb both formaldehyde and toluene. Combining these two properties in latex paint not only degrades formaldehyde but also improves the mechanical properties of the latex paint, achieving multiple functions and thus realizing highly efficient formaldehyde removal.

Claims

1. An antibacterial environment-friendly emulsion paint, characterized in that, The composition comprises the following raw materials by weight: acrylic emulsion 200-300 parts, functionalized bentonite 30-50 parts, calcium carbonate 50-100 parts, polyacrylamide 1-5 parts, polyoxypropylene polyoxyethylene glycerol ether 5-20 parts, stearic acid amide 0.5-2 parts, film forming agent 2-8 parts, leveling agent 0.1-3 parts, hydroxypropyl methyl cellulose 1-5 parts, defoaming agent 3-9 parts, sodium bicarbonate 0.1-1 part, water 120-240 parts, multifunctional antibacterial agent 5-15 parts; The preparation method of the functionalized bentonite is as follows: According to weight parts, 70-100 parts of bentonite is added into 200-400 parts of water for ultrasonic dispersion for 5-10 min; then 5-10 parts of didecyl dimethyl ammonium chloride and 3-5 parts of imidazole alkyl urea are added, and stirring is carried out at 60-65℃ and 200-500 rpm for 3-6 h, filtration is carried out, and vacuum drying is carried out at 70-80℃ for 8-10 h to obtain pretreated bentonite; 30-60 parts of the pretreated bentonite, 5-10 parts of silicon powder, 1-2 parts of sodium tripolyphosphate and 1-3 parts of tris(dimethylsiloxane) silane are taken into a ball mill for treatment for 2-4 h at a ball milling speed of 150-350 rpm to obtain the functionalized bentonite; The multifunctional antibacterial agent is a chitosan compound; and the preparation method of the chitosan compound is as follows: (1) according to weight parts, 20-40 parts of di(2-hydroxypropionic acid) dihydroxylated titanium diammonium, 2-8 parts of acetylacetone, 2-6 parts of polyethylene glycol and 120-200 parts of anhydrous ethanol are mixed, stirring is carried out at 400-600 rpm for 10-30 min, 1-3 mol / L hydrochloric acid is used to adjust the pH to 2.5-4, and reaction is carried out at 50-70℃ and 500-700 rpm for 1-4 h to obtain titanium dioxide colloid; (2) 10-30 parts of dicyandiamide and all the above titanium dioxide colloid are mixed, heated to 450-600℃ at a heating rate of 3-7℃ / min in a muffle furnace, calcined for 4-8 h in a nitrogen environment, naturally cooled, ground, and sieved through a 700-1000 mesh sieve to obtain a C3N4 / TiO2 composite; (3) 5-12 parts of chitosan and 200-350 parts of 1-5 wt% hydrochloric acid aqueous solution are mixed, ultrasonic treatment is carried out at 25-40℃, an ultrasonic frequency of 20-40 kHz and an ultrasonic power of 100-300 W for 20-40 min; 30-60 parts of liquid paraffin and 0.5-2 parts of polyethylene glycol are added, stirring is carried out at 800-1100 rpm for 10-30 min; 3-15 parts of a modifier is further added, stirring is carried out at 35-60℃ and 300-500 rpm for 3-5 h, filtration is carried out, washing is carried out with anhydrous ethanol, and vacuum drying is carried out at 60-80℃ for 8-16 h to obtain modified porous chitosan microspheres. (4) taking 3-8 parts of modified porous chitosan microspheres, 5-12 parts of C3N4 / TiO2 composite, 40-100 parts of water, mixing, ultrasonic dispersion at ultrasonic frequency of 30-60 kHz and ultrasonic power of 200-400 W for 20-40 min, adding 2-5 parts of glutaraldehyde, adjusting pH to 9-11 with 1-4 mol / L potassium hydroxide aqueous solution, reacting at 60-80℃ and 100-300 rpm for 2-5 h, filtering, washing with anhydrous ethanol, and vacuum drying at 60-80℃ for 8-16 h to obtain a chitosan composite; the modifier is composed of malonic anhydride and hydroxypropyltrimethylammonium chloride according to a mass ratio of (1-3):(1-5).

2. The antibacterial environment-friendly emulsion paint according to claim 1, characterized in that, The defoaming agent is one or more than two of polyether defoaming agent, silicone defoaming agent, high-carbon alcohol defoaming agent, and mineral oil.

3. The antibacterial environment-friendly emulsion paint according to claim 1, wherein the antibacterial environment-friendly emulsion paint is a latex paint. The leveling agent is at least one of polyurethane leveling agent and silicone leveling agent.

4. The antibacterial environment-friendly emulsion paint according to claim 1, wherein the antibacterial environment-friendly emulsion paint is a latex paint. The film-forming agent is selected from one or more of propylene glycol methyl ether acetate, dodecanol ester, diethylene glycol butyl ether, propylene glycol butyl ether, and hexylene glycol butyl ether acetate.

5. The antibacterial environment-friendly emulsion paint according to claim 1, wherein the antibacterial environment-friendly emulsion paint is a latex paint. The following raw materials are included in the composition: 220 parts of acrylic emulsion, 40 parts of functionalized bentonite, 70 parts of calcium carbonate, 4 parts of polyacrylamide, 15 parts of polyoxypropylene polyoxyethylene glycerol ether, 1 part of stearyl amide, 6 parts of diethylene glycol butyl ether, 2 parts of dimethyl silicone, 4 parts of hydroxypropyl methyl cellulose, 6 parts of dimethyl silicone, 0.5 parts of sodium bicarbonate, 200 parts of water, and 10 parts of multifunctional antibacterial agent. The preparation method of the functionalized bentonite is as follows: According to parts by weight, 80 parts of bentonite is added to 300 parts of water and ultrasonically dispersed for 6 min; then 7.5 parts of didodecyldimethylammonium chloride and 3.5 parts of imidazole alkyl urea are added, and stirring is performed at 63℃ and 300 rpm for 5 h, filtering, and vacuum drying at 70℃ for 10 h to obtain pretreated bentonite; 50 parts of the pretreated bentonite, 8 parts of silicon powder, 1.5 parts of sodium tripolyphosphate, and 2 parts of tris(dimethylsiloxane) silane are added to a ball mill and treated for 2.5 h at a ball milling speed of 200 rpm to obtain the functionalized bentonite; The multifunctional antibacterial agent is a chitosan composite, and the preparation method of the chitosan composite is as follows: (1) According to parts by weight, 30 parts of di(2-hydroxypropionic acid) dihydroxylammonium titanium, 3 parts of acetylacetone, 3 parts of polyethylene glycol, and 160 parts of anhydrous ethanol are mixed, stirring is performed at 500 rpm for 20 min, 2 mol / L hydrochloric acid is used to adjust pH to 3, and reaction is performed at 60℃ and 600 rpm for 2 h to obtain titanium dioxide colloid; (2) 20 parts of dicyandiamide and all of the above titanium dioxide colloid are mixed, heated to 550℃ at a heating rate of 5℃ / min in a muffle furnace, calcined in a nitrogen environment for 6 h, naturally cooled, ground, and sieved through an 800-mesh sieve to obtain a C3N4 / TiO2 composite. (3) 10 parts of chitosan and 300 parts of 2wt% hydrochloric acid aqueous solution were mixed, and ultrasonic treatment was carried out at 30°C, an ultrasonic frequency of 30 kHz and an ultrasonic power of 200 W for 30 min; 50 parts of liquid paraffin and 1 part of polyethylene glycol were added, and stirring was carried out at 1000 rpm for 20 min; 10 parts of a modifier were added, and stirring was carried out at 50°C and 400 rpm for 4 h; filtration was carried out, and the product was washed with anhydrous ethanol and dried at 70°C under vacuum for 10 h to obtain modified porous chitosan microspheres; (4) 5 parts of modified porous chitosan microspheres, 10 parts of C3N4 / TiO2 composite and 50 parts of water were mixed, and ultrasonic treatment was carried out at an ultrasonic frequency of 40 kHz and an ultrasonic power of 300 W for 30 min; 3 parts of glutaraldehyde were added, and the pH was adjusted to 10 with 2mol / L potassium hydroxide aqueous solution; reaction was carried out at 70°C and 200 rpm for 3 h; filtration was carried out, and the product was washed with anhydrous ethanol and dried at 70°C under vacuum for 10 h to obtain a chitosan composite; The modifier is malonic anhydride and hydroxypropyltrimethylammonium chloride, and the mass ratio is 2:

3.

6. The method of claim 1-5, wherein the method is characterized by, The method comprises the following steps: S1, weighing each material; S2, mixing water, acrylic emulsion, stearyl amide, polyoxypropylene polyoxyethylene glycerol ether and hydroxypropyl methyl cellulose, and stirring at 400-800 rpm for 30-60 min to obtain a slurry; S3, mixing polyacrylic acid amide, film forming agent, functionalized bentonite, calcium carbonate, leveling agent, defoaming agent, sodium bicarbonate and multifunctional antibacterial agent, and adding to the slurry, and stirring at 800-1200 rpm for 40-90 min to obtain an antibacterial environment-friendly latex paint.

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