High-performance environment-friendly coating for building external wall and preparation method thereof

Abstract

The invention discloses a high-performance environment-friendly coating for a building external wall and a preparation method thereof, and belongs to the technical field of coatings. The coating is prepared from the following raw materials: 70 to 80 parts of styrene-acrylic emulsion, 30 to 40 parts of water, 15 to 25 parts of hollow glass beads, 5 to 10 parts of a coalescing agent, 5 to 10 parts of modified titanium dioxide, 5 to 10 parts of ground calcium carbonate, 1 to 3 parts of a thickening agent, 0.8 to 2 parts of an auxiliary agent, 0.5 to 1 part of a dispersing agent, 0.5 to 1 part of a defoaming agent, 0.5 to 1 part of a wetting agent, 0.5 to 1 part of a pH regulator and 0.04 to 0.06 part of an initiator. The auxiliary agent containing a thiazole structure and a hindered phenol structure contains ester groups, hydroxyl groups, benzene rings and the like, chemical effects exist among the auxiliary agent, the benzo emulsion and the modified titanium dioxide, and the auxiliary agent is highly dispersed and stably exists in the coating under the action of the dispersing agent, so that the coating is endowed with lasting and efficient antibacterial and anti-aging effects; the coating also has excellent adhesive force, heat insulation and heat preservation effects and impact resistance.

Description

Technical Field

[0001] The present invention belongs to the technical field of coatings, and in particular relates to a high-performance environmentally friendly coating for building exterior walls and a preparation method thereof. Background Art

[0002] Architectural coatings can not only make the inside and outside of buildings neat and beautiful, but also protect the coated building materials, extend their service life and improve the use effect of the building inside and outside. This plays an important role in beautifying life and beautifying the environment. Architectural coatings are a kind of building finishing material made of organic high molecular polymers as the main film-forming substance, with additives, pigments, fillers, dispersants, etc., and made through processes such as batching, stirring, and grinding.

[0003] Some exterior wall coatings age within a few months or a year or two after application due to natural conditions and light radiation, resulting in gloss loss, fading, chalking, cracking, flaking, and even complete loss of the coating. This severely damages the coating's aesthetic properties and protective properties. This not only results in significant economic losses and waste of resources, but also poses a significant environmental risk due to the aging and decomposition of exterior wall coatings. Furthermore, the moisture and nutrients contained in paint make it susceptible to bacterial contamination, leading to harmful physical and chemical changes in the paint. Summary of the Invention

[0004] The purpose of the present invention is to overcome the defects of the prior art and provide a high-performance environmentally friendly coating for building exterior walls and a preparation method thereof.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A high-performance environmentally friendly coating for building exterior walls, comprising the following raw materials in parts by weight: 70-80 parts of styrene-acrylic emulsion, 30-40 parts of water, 15-25 parts of hollow glass microspheres, 5-10 parts of a film-forming aid, 5-10 parts of modified titanium dioxide, 5-10 parts of heavy calcium carbonate, 1-3 parts of a thickener, 0.8-2 parts of an additive, 0.5-1 parts of a dispersant, 0.5-1 parts of a defoaming agent, 0.5-1 parts of a wetting agent, 0.5-1 parts of a pH regulator, and 0.04-0.06 parts of an initiator;

[0007] Furthermore, the size of the hollow glass microspheres is less than 100 mesh.

[0008] Hollow glass microspheres with closed hollow spheres can be added to the paint to form many microscopic independent insulating cavities, which greatly improve the insulation of the coating against heat and sound, thereby playing a good role in thermal insulation and noise reduction; the spherical hollow glass microsphere structure added to the paint can well disperse the impact force and stress, thereby improving the coating's resistance to external impact, and can also reduce the stress cracking of the coating caused by thermal expansion and contraction; hollow glass microspheres can also effectively enhance the adhesion of the coating and prevent the coating from yellowing and aging to a certain extent.

[0009] Furthermore, the film-forming aid is one or more of lauryl alcohol ester, ethylene glycol butyl ether acetate, and propylene glycol methyl ether acetate.

[0010] Furthermore, the modified titanium dioxide is prepared by the following steps:

[0011] Dried titanium dioxide was dispersed in anhydrous ethanol, acetic acid was added to adjust the pH to 4, stirred for 30 minutes, and transferred to a three-necked flask; KH570 (γ-methacryloxypropyltrimethoxysilane) was dispersed in deionized water, stirred for 15 minutes, and then transferred to the above three-necked flask. After the transfer was completed, the temperature was raised to 65°C and reacted for 1 hour. After the reaction was completed, it was cooled to room temperature and centrifuged. The precipitate was ultrasonically vibrated in anhydrous ethanol for 10 minutes and dried to obtain modified titanium dioxide; the mass ratio of titanium dioxide to KH570 was 1:0.06.

[0012] Titanium dioxide can improve the visual effect of the paint. It also has excellent anti-ultraviolet properties, which can effectively prevent ultraviolet rays from eroding and damaging the paint, and delay the aging and fading of the paint. In addition, titanium dioxide also has a certain antibacterial effect and can maintain the hygiene of the paint surface to a certain extent.

[0013] The silanol groups generated by KH570 after hydrolysis react with the hydroxyl groups on the surface of titanium dioxide to form stable chemical bonds. The formation of new chemical bonds reduces the surface energy of titanium dioxide, making titanium dioxide stable. At the same time, the organic medium on the surface of the particles increases the spatial resistance to agglomeration between particles, thereby making the titanium dioxide well dispersed. At the same time, the modified titanium dioxide contains double bonds, which can react chemically with the double bonds in the styrene-acrylic emulsion and the auxiliary agent under the action of an initiator, so that the modified titanium dioxide is highly dispersed and stably present in the coating, while also promoting the dispersibility of the auxiliary agent. Therefore, the titanium dioxide of the present invention can improve the visual effect of the coating and give full play to its anti-ultraviolet and antibacterial effects. At the same time, the titanium dioxide of the present invention and the auxiliary agent work synergistically, so that the coating of the present invention has excellent anti-aging and antibacterial properties.

[0014] Furthermore, the thickener is one or more of hydroxymethyl cellulose, hydroxyethyl cellulose, and hydroxypropyl ethyl cellulose.

[0015] Furthermore, the auxiliary agent is prepared by the following steps:

[0016] S1. First, a dry brown four-necked flask was purged with nitrogen for 30 minutes, and then 2-(2-benzothiazolylthio)ethanol, methylvinyldimethoxysilane, tetraisopropyl titanate and toluene were added, stirred and dissolved, and the temperature was raised to 100°C. The reaction was kept warm for 36 hours. After the reaction was completed, it was cooled to room temperature and distilled under reduced pressure. The product was washed with anhydrous ethanol 5 times and finally dried at 80°C for 12 hours. The entire process was carried out under nitrogen protection to obtain intermediate 1; the amount ratio of 2-(2-benzothiazolylthio)ethanol, methylvinyldimethoxysilane, tetraisopropyl titanate and toluene was 11.6 g:9.1 mL:0.052 g:140 mL;

[0017] Under the catalytic action of tetraisopropyl titanate, the molar ratio of methylvinyldimethoxysilane and 2-(2-benzothiazolylthio)ethanol is controlled to be 1.05-1.1:1, and the -OH group of 2-(2-benzothiazolylthio)ethanol and the -Si-O- group of methylvinyldimethoxysilane undergo the following chemical reaction. The reaction process is shown below:

[0018]

[0019] S2. First, a dry brown four-necked flask was purged with nitrogen for 30 minutes, and then 3,5-di(tert-butyl)-4-hydroxy-phenylpropionic acid, 3-hydroxy-2,2-bis(hydroxymethyl)propyl ester, intermediate 1, tetraisopropyl titanate and DMSO (dimethyl sulfoxide) were added, stirred and dissolved, heated to 100°C, and kept warm for 48 hours. After the reaction, it was cooled to room temperature, distilled under reduced pressure, washed with anhydrous ethanol 5 times, and finally dried at 80°C for 12 hours. The whole process was carried out under nitrogen protection to obtain intermediate 2; the amount ratio of 3,5-di(tert-butyl)-4-hydroxy-phenylpropionic acid, 3-hydroxy-2,2-bis(hydroxymethyl)propyl ester, intermediate 1, tetraisopropyl titanate and DMSO was 13.9g:22.3g:0.061g:180mL;

[0020] Under the catalytic action of tetraisopropyl titanate, the molar ratio of 3,5-di(tert-butyl)-4-hydroxy-phenylpropionic acid, 3-hydroxy-2,2-bis(hydroxymethyl)propyl ester and intermediate 1 is controlled to be 1:2.05-2.1, and the -OH of 3,5-di(tert-butyl)-4-hydroxy-phenylpropionic acid, 3-hydroxy-2,2-bis(hydroxymethyl)propyl ester and -Si-O- of intermediate 1 undergo the following chemical reaction. The reaction process is shown below:

[0021]

[0022] S3. Under nitrogen, add Intermediate 2 and DMF to a dry brown four-necked flask. Heat to 40°C and stir until completely dissolved. Then slowly add glycidyl methacrylate. After addition, heat to 80°C and incubate for 6 hours. After completion of the reaction, cool to room temperature and evaporate under reduced pressure. Purify by column chromatography (using a mixed solvent of cyclohexane and ethyl acetate in a 1:1 volume ratio as the eluent). Evaporate under reduced pressure to obtain the auxiliary agent. The ratio of Intermediate 2, glycidyl methacrylate, and DMF is 13.5 g:4 mL:140 mL.

[0023] The intermediate 2-OH and the epoxy group of glycidyl methacrylate undergo a nucleophilic substitution reaction under heating conditions. The reaction process is as follows:

[0024]

[0025] The additive contains a high density of thiazole structures. The thiazole structure has a unique electron-rich nitrogen, sulfur heteroatom and five-membered heterocyclic structure, which is easy to form non-covalent bonds with key bacterial metabolic enzymes, interfering with the normal metabolic process, thereby achieving an antibacterial effect; the additive contains a hindered phenol structure. Since the hydroxyl group of the hindered phenol structure is restricted by spatial barriers, the hydrogen atom can easily fall off from the original molecular structure, thereby achieving the effect of donating protons and combining with peroxyl free radicals, alkyl free radicals, hydroxyl free radicals, etc., causing it to lose its original activity and leading to oxygen aging. The reaction is terminated; the additive contains multiple benzene rings, and due to similar miscibility, the additive has good compatibility with the other raw materials and can be well dispersed in the coating; the additive contains multiple carbon-carbon double bonds, which, under the action of the initiator, can produce a chemical reaction with the unreacted double bonds in the styrene-acrylic emulsion and the double bonds on the surface of the modified titanium dioxide. In addition, due to the effects of the dispersant, etc., the additive, modified titanium dioxide, and styrene-acrylic emulsion of the present invention can all be highly dispersed and stably present in the coating. Therefore, the additive of the present invention can exert long-lasting and efficient antibacterial and anti-aging effects.

[0026] Furthermore, the dispersant is one or more polyacrylate dispersants.

[0027] Furthermore, the defoaming agent is one or more of a polyether defoaming agent and a silicone defoaming agent.

[0028] Furthermore, the wetting agent is a polyether-modified organosiloxane copolymer wetting agent.

[0029] Furthermore, the pH regulator is aqueous ammonia.

[0030] Furthermore, the initiator is 2,4,6-trimethylbenzoyl-diphenylphosphine oxide.

[0031] A method for preparing a high-performance environmentally friendly coating for building exterior walls comprises the following steps:

[0032] The raw materials are weighed according to the formula, and a dispersant, a wetting agent, 40 wt% of a defoaming agent and water are stirred at a rate of 400-500 r / min for 0.5 h. Then, modified titanium dioxide, heavy calcium carbonate and hollow glass microspheres are added and stirred at a rate of 1000-2000 r / min for 0.5 h, and mixed thoroughly without agglomeration; subsequently, a styrene-acrylic emulsion, an auxiliary agent and an initiator are added, and stirred at a rate of 400-500 r / min for 45 min. After being thoroughly mixed, the remaining defoaming agent and film-forming auxiliary agent are slowly added, and stirring is continued for 0.5 h; finally, a pH regulator is used to adjust the pH to between 8 and 9, a thickener is added, and stirring is carried out at a rate of 400-500 r / min for 15 min to obtain a high-performance environmentally friendly coating for building exterior walls.

[0033] The beneficial effects of the present invention are as follows: the additives containing thiazole structures and hindered phenol structures contain multiple ester groups, hydroxyl groups and benzene rings, and there is a chemical reaction between the additives and the benzo emulsion and modified titanium dioxide. In addition, due to the effects of the dispersant, etc., the additives of the present invention are highly dispersed and stably present in the coating, giving the coating long-lasting and efficient antibacterial and anti-aging effects; under the action of hollow glass microspheres, titanium dioxide, etc., the coating of the present invention also has excellent adhesion, thermal insulation effects, as well as excellent impact resistance, aging resistance and antibacterial properties. DETAILED DESCRIPTION

[0034] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0035] Example 1

[0036] Preparation of modified titanium dioxide, the specific steps are as follows:

[0037] Take 5g of dry titanium dioxide and disperse it in 80mL of anhydrous ethanol, add acetic acid to adjust the pH to 4, stir for 30min, and transfer it to a 250mL three-necked flask; disperse 0.3g of KH570 in 20mL of deionized water, stir for 15min, and then transfer it to the above 250mL three-necked flask. After the transfer is completed, heat it to 65℃ and react for 1h. After the reaction is completed, cool it to room temperature, centrifuge it, take the precipitate and ultrasonically vibrate it in anhydrous ethanol for 10min, and dry it to obtain modified titanium dioxide.

[0038] Example 2

[0039] Preparation of auxiliary agent, the specific steps are as follows:

[0040] S1. First, a dry brown four-necked flask was purged with nitrogen for 30 minutes, and then 11.6 g of 2-(2-benzothiazolylthio)ethanol, 9.1 mL of methylvinyldimethoxysilane, 0.052 g of tetraisopropyl titanate and 140 mL of toluene were added, stirred and dissolved, and the temperature was raised to 100°C. The reaction was kept warm for 36 hours. After the reaction was completed, it was cooled to room temperature and distilled under reduced pressure. The product was washed with anhydrous ethanol 5 times and finally dried at 80°C for 12 hours. The entire process was carried out under nitrogen protection to obtain intermediate 1;

[0041] S2. First, a dry 500 mL brown four-necked flask was purged with nitrogen for 30 min, and then 13.9 g of 3,5-di(tert-butyl)-4-hydroxy-phenylpropionic acid, 3-hydroxy-2,2-bis(hydroxymethyl)propyl ester, 22.3 g of intermediate 1, 0.061 g of tetraisopropyl titanate and 180 mL of DMSO were added, stirred and dissolved, and the temperature was raised to 100 ° C. and kept for 48 h. After the reaction was completed, it was cooled to room temperature and distilled under reduced pressure. The product was washed with anhydrous ethanol 5 times and finally dried at 80 ° C for 12 h. The whole process was carried out under nitrogen protection to obtain intermediate 2;

[0042] S3. Under nitrogen protection, 13.5 g of intermediate 2 and 140 mL of DMF were added to a dry 250 mL brown four-necked flask, the temperature was raised to 40 ° C and stirred until completely dissolved, and then 4 mL of glycidyl methacrylate was slowly added. After the addition was completed, the temperature was raised to 80 ° C. and the reaction was kept warm for 6 hours. After the reaction was completed, it was cooled to room temperature and distilled under reduced pressure. Purification by column chromatography (a mixed solvent of cyclohexane and ethyl acetate was selected as the eluent, and the volume ratio of cyclohexane and ethyl acetate was 1:1), and distilled under reduced pressure to obtain an auxiliary agent.

[0043] Example 3

[0044] The specific steps for preparing high-performance environmentally friendly coatings for building exterior walls are as follows:

[0045] 0.5 parts of dispersant 5040, 0.5 parts of wetting agent BYK-348, 0.2 parts of defoamer JY-821 of Jiangsu Jianyu Additive Technology Co., Ltd. and 30 parts of water were stirred at 400 r / min for 0.5 h, then 5 parts of modified titanium dioxide of Example 1, 5 parts of heavy calcium carbonate and 15 parts of hollow glass microspheres were added and stirred at 1000 r / min for 0.5 h, and mixed thoroughly without agglomeration; then 70 parts of styrene acrylic emulsion, 0.8 parts of auxiliary agent of Example 2 were added. agent, 0.04 parts of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, stirred at a rate of 400r / min for 45min, and after fully mixing, slowly added 0.3 parts of defoaming agent JY-821 produced by Jiangsu Jianyu Additive Technology Co., Ltd. and 5 parts of propylene glycol methyl ether acetate, and continued stirring for 0.5h; finally, adjusted the pH to 8 with 0.5 parts of ammonia water, added 1 part of hydroxymethyl cellulose, and stirred at a rate of 400r / min for 15min to obtain a high-performance environmentally friendly coating for building exterior walls.

[0046] Example 4

[0047] The specific steps for preparing high-performance environmentally friendly coatings for building exterior walls are as follows:

[0048] 0.8 parts of dispersant 5040, 0.8 parts of wetting agent BYK-348, 0.32 parts of polydimethylsiloxane and 38 parts of water were stirred at a rate of 450 r / min for 0.5 h, followed by the addition of 9 parts of modified titanium dioxide of Example 1, 8 parts of heavy calcium carbonate, 20 parts of hollow glass microspheres and stirring at a rate of 1500 r / min for 0.5 h, and thoroughly mixed without agglomeration; then 78 parts of styrene acrylic emulsion, 1.8 parts of the auxiliary agent of Example 2, 0 0.05 parts of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide were added, stirred at a rate of 450 r / min for 45 minutes, and after being fully mixed, 0.48 parts of polydimethylsiloxane and 9 parts of ethylene glycol butyl ether acetate were slowly added, and stirring was continued for 0.5 hours; finally, 0.8 parts of ammonia water were used to adjust the pH to 8.5, 2 parts of hydroxypropyl ethyl cellulose were added, and stirring was continued at a rate of 450 r / min for 15 minutes to obtain a high-performance environmentally friendly coating for building exterior walls.

[0049] Example 5

[0050] The specific steps for preparing high-performance environmentally friendly coatings for building exterior walls are as follows:

[0051] 1 part of dispersant 5040, 1 part of wetting agent BYK-348, 0.4 part of defoamer JY-930 of Jiangsu Jianyu Additive Technology Co., Ltd. and 40 parts of water were stirred at 500 r / min for 0.5 h, then 10 parts of modified titanium dioxide of Example 1, 10 parts of heavy calcium carbonate and 25 parts of hollow glass microspheres were added and stirred at 2000 r / min for 0.5 h, and mixed thoroughly without lumps; then 80 parts of styrene acrylic emulsion and 2 parts of additives of Example 2 were added. , 0.06 parts of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, stirred at a rate of 500r / min for 45 minutes, and after fully mixing, slowly added 0.6 parts of defoamer JY-930 and 10 parts of dodecyl alcohol ester from Jiangsu Jianyu Additive Technology Co., Ltd., and continued stirring for 0.5h; finally, adjusted the pH to 9 with 1 part of ammonia water, added 3 parts of hydroxyethyl cellulose, and stirred at a rate of 500r / min for 15 minutes to obtain a high-performance environmentally friendly coating for building exterior walls.

[0052] Comparative Example 1

[0053] Preparation of coatings for building exterior walls, the specific steps are as follows:

[0054] The remaining steps remained unchanged, except that the titanium dioxide in Example 5 was replaced by titanium dioxide without any treatment to prepare a coating for building exterior walls.

[0055] Comparative Example 2

[0056] Preparation of coatings for building exterior walls, the specific steps are as follows:

[0057] The remaining steps remained unchanged, except that the auxiliary agent in Comparative Example 1 was replaced by 1 part of nano-silver antibacterial agent and 1 part of β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate to prepare a coating for building exterior walls.

[0058] Comparative Example 3

[0059] Preparation of coatings for building exterior walls, the specific steps are as follows:

[0060] The remaining steps remain unchanged, and the modified titanium dioxide and the additives in Example 5 are removed to prepare a coating for building exterior walls.

[0061] Performance Testing

[0062] The exterior building wall coatings prepared in Examples 3-5 and Comparative Examples 1-3 were tested according to the HG / T3950-2007 method. The test results are shown in Table 1 below:

[0063] When the antibacterial rate is ≥99%, the antibacterial performance is level I; when it is ≥90%, the antibacterial performance is level II;

[0064] Antibacterial rate ≥95%, antibacterial durability is level I, ≥85%, antibacterial performance is level II;

[0065] Table 1

[0066]

[0067] “-” means no antibacterial property.

[0068] It can be seen from the data in Table 1 that the exterior building wall coating prepared in the embodiment of the present invention has excellent antibacterial performance, and the exterior building wall coating in the embodiment of the present invention also has better antibacterial durability.

[0069] The aging resistance test results of the coating films formed by spraying the coatings for building exterior walls prepared in Examples 3-5 and Comparative Examples 1-3 are shown in Table 2 below:

[0070] Table 2

[0071] Artificial aging resistance / h UV resistance time / h Example 3 3300 950 Example 4 3300 950 Example 5 3400 955 Comparative Example 1 3100 930 Comparative Example 2 3000 915 Comparative Example 3 1600 520

[0072] It can be seen from the data in Table 2 that the exterior wall coating prepared in the embodiment of the present invention has high-efficiency and long-lasting anti-aging performance.

[0073] The coating adhesion test was conducted using the GB / T9286-1998 "Scratch Test for Paint and Varnish Films" standard. The coating water resistance and alkali resistance tests and specimen preparation all followed the GB / T9755-2014 "Synthetic Resin Emulsion Exterior Wall Paints" standard. The test results are shown in Table 3:

[0074] Table 3

[0075] Adhesion / Grade 96h water resistance 48h alkali resistance Example 3 0 No abnormalities No abnormalities Example 4 0 No abnormalities No abnormalities Example 5 0 No abnormalities No abnormalities Comparative Example 1 0 No abnormalities No abnormalities Comparative Example 2 0 No abnormalities No abnormalities Comparative Example 3 1 Wrinkling and shedding Wrinkling and shedding

[0076] The coatings prepared in Examples 3-5 and Comparative Examples 1-3 were placed in plastic cups for drying and then cut into samples with a thickness of 2 mm and a diameter of 10 mm. The thermal conductivity of the samples was measured at 25°C using a thermal conductivity analyzer in accordance with the standard GB / T 10294-2008 "Insulating materials - Determination of steady-state thermal resistance and related properties - Guarded hot plate method". The results are shown in Table 4.

[0077] Table 4

[0078] project Thermal conductivity W / (m﹒k) Example 3 0.129 Example 4 0.129 Example 5 0.127 Comparative Example 1 0.135 Comparative Example 2 0.136 Comparative Example 3 0.138

[0079] Throughout the specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0080] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the described specific embodiments or replace them in similar ways. As long as they do not deviate from the invention or exceed the scope defined by the claims, they should all fall within the scope of protection of the present invention.

Claims

1. A high-performance environmentally friendly coating for building exterior walls, characterized in that: The invention comprises the following raw materials in parts by weight: 70-80 parts of styrene-acrylic emulsion, 30-40 parts of water, 15-25 parts of hollow glass microspheres, 5-10 parts of film-forming aid, 5-10 parts of modified titanium dioxide, 5-10 parts of heavy calcium carbonate, 1-3 parts of thickener, 0.8-2 parts of auxiliary agent, 0.5-1 parts of dispersant, 0.5-1 parts of defoaming agent, 0.5-1 parts of wetting agent, 0.5-1 parts of pH regulator and 0.04-0.06 parts of initiator. Wherein, the auxiliary agent is prepared by the following steps: S1. After nitrogen was blown into the flask, 2-(2-benzothiazolylthio)ethanol, methylvinyldimethoxysilane, tetraisopropyl titanate, and toluene were added, stirred, heated to 100°C, reacted for 36 hours, cooled, distilled under reduced pressure, washed, and dried to obtain intermediate 1; S2. After nitrogen is blown into the flask, 3,5-di(tert-butyl)-4-hydroxy-phenylpropionic acid, 3-hydroxy-2,2-bis(hydroxymethyl)propyl ester, intermediate 1, tetraisopropyl titanate and DMSO are added, stirred, heated to 100°C and reacted for 48 hours, cooled, distilled under reduced pressure, washed and dried to obtain intermediate 2; S3. Under nitrogen protection, add intermediate 2 and DMF into a flask, heat to 40°C, then add glycidyl methacrylate, heat to 80°C, react for 6 hours, cool, distill under reduced pressure, purify by column chromatography, and distill under reduced pressure to obtain an auxiliary agent.

2. A high-performance environmentally friendly coating for building exterior walls according to claim 1, characterized in that: The amount ratio of 2-(2-benzothiazolylthio)ethanol, methylvinyldimethoxysilane, tetraisopropyl titanate and toluene in step S1 is 11.6 g:9.1 mL:0.052 g:140 mL; the amount ratio of 3,5-di(tert-butyl)-4-hydroxy-benzenepropionic acid, 3-hydroxy-2,2-bis(hydroxymethyl)propyl ester, intermediate 1, tetraisopropyl titanate and DMSO in step S2 is 13.9 g:22.3 g:0.061 g:180 mL; the amount ratio of intermediate 2, glycidyl methacrylate and DMF in step S3 is 13.5 g:4 mL:140 mL.

3. The high-performance environmentally friendly coating for building exterior walls according to claim 1, characterized in that: The size of the hollow glass microspheres is less than 100 meshes.

4. The high-performance environmentally friendly coating for building exterior walls according to claim 1, characterized in that: The film-forming aid is one or more of lauryl alcohol ester, ethylene glycol butyl ether acetate, and propylene glycol methyl ether acetate.

5. The high-performance environmentally friendly coating for building exterior walls according to claim 1, characterized in that: The modified titanium dioxide is prepared by the following steps: Titanium dioxide was dispersed in anhydrous ethanol, acetic acid was added to adjust the pH to 4, and the mixture was transferred to a flask. KH570 was dispersed in deionized water and then transferred to the above flask. The mixture was heated to 65°C and reacted for 1 hour. The mixture was cooled and centrifuged. The precipitate was ultrasonically vibrated in anhydrous ethanol and dried to obtain modified titanium dioxide. The mass ratio of titanium dioxide to KH570 was 1:0.

06.

6. The high-performance environmentally friendly coating for building exterior walls according to claim 1, characterized in that: The thickener is one or more of hydroxymethyl cellulose, hydroxyethyl cellulose, and hydroxypropyl ethyl cellulose; and the dispersant is one or more of polyacrylate type dispersants.

7. The high-performance environmentally friendly coating for building exterior walls according to claim 1, characterized in that: The defoaming agent is one or more of a polyether defoaming agent and an organosilicon defoaming agent; the wetting agent is a polyether modified organosiloxane copolymer wetting agent; and the pH regulator is ammonia water.

8. The high-performance environmentally friendly coating for building exterior walls according to claim 1, characterized in that: The initiator is 2,4,6-trimethylbenzoyl-diphenylphosphine oxide.

9. The method for preparing a high-performance environmentally friendly coating for building exterior walls according to claim 1, characterized in that: The following steps are involved: The raw materials are weighed according to the formula, and a dispersant, a wetting agent, 40 wt% of a defoaming agent and water are uniformly stirred. Then, modified titanium dioxide, heavy calcium carbonate and hollow glass microspheres are added and stirred. Subsequently, a styrene-acrylic emulsion, an auxiliary agent and an initiator are added and stirred. The remaining defoaming agent and film-forming auxiliary agent are added and stirred continuously. Finally, a pH regulator is used to adjust the pH, a thickener is added and stirred to obtain a high-performance environmentally friendly coating for building exterior walls.

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