Waterproof alkali-resistant exterior wall paint and preparation method thereof

Abstract

The invention relates to the technical field of exterior wall paint, and discloses waterproof alkali-resistant exterior wall paint and a preparation method thereof.Bis (4-chlorphenyl) amine, allyltrimethoxysilane, 1-bromo-1H, 1H, 2H, 2H-perfluorodecane and the like are used as raw materials and react with hydroxyl in epoxy resin E51 to obtain organic silicon-fluorine epoxy emulsion, and the organic silicon-fluorine epoxy emulsion is added into the epoxy resin E51 to obtain the waterproof alkali-resistant exterior wall paint. Uniformly mixing with acrylic resin emulsion, ground calcium carbonate, related auxiliaries and the like; substances with low surface energy, such as organic fluorine and silicon, are introduced into the organic silicon-fluorine epoxy emulsion, so that the surface energy is reduced, water drops cannot stay on the surface, and a waterproof effect is realized; silanol formed after siloxane hydrolysis and carboxyl substances of the acrylic emulsion are subjected to a cross-linking reaction, alkali and salt are prevented from migrating to the surface, and the alkali-resistant effect is achieved; the quaternary ammonium salt group mainly plays a bactericidal role, the permeability of escherichia coli cell membranes is changed, the antibacterial and mildew-proof purposes are achieved, and the prepared exterior wall paint is free of VOC emission, green, environmentally friendly and wide in application range.

Description

Technical Field

[0001] The invention relates to the technical field of exterior wall paints, in particular to a waterproof and alkali-resistant exterior wall paint and a preparation method thereof. Background Art

[0002] With the continuous advancement of modern construction technology, exterior wall paint is an important component of the exterior wall of a building. In order to ensure the long-term stability and aesthetics of the building, the performance and quality requirements of the exterior wall paint are also increasing. The base material of the exterior wall of a building is generally mortar concrete, in which cement and lime have strong alkalinity. As the moisture of the base layer evaporates, the alkali and soluble salts in the cement will seep out from the cement pores through the coating in the form of an aqueous solution, and calcium hydroxide will be brought to the surface to react with carbon dioxide in the air to form insoluble carbonates, which can easily cause discoloration, fading and peeling of the exterior wall. At the same time, the base material of the exterior wall of a building is mostly a concrete surface, and its porous structure makes it highly water-absorbent, resulting in the surface of the decorative coating being not smooth enough, easily causing the paint film to wrinkle, and may cause the paint film to dry too quickly and cause the topcoat to crack. However, many exterior wall paints on the market are still insufficient in terms of waterproofness and alkali resistance, so it is particularly important to develop an exterior wall paint with excellent waterproof and alkali resistance.

[0003] Traditional exterior wall paints often use common alkali-resistant primer emulsions, which have poor quality and low content, resulting in low final film-forming efficiency and poor alkali-resistant sealing performance, thereby affecting the protection of the substrate and the appearance of the paint film; for example, patent No. CN105482570B discloses an exterior wall alkali-resistant primer and a preparation method thereof, which includes: a water-based primer emulsion, a pigment, a filler, a wetting agent, a dispersant, a pH adjuster, a preservative, a slow-release naphthalene-based water reducer, etc., which can prevent the alkali solution generated by cement mortar from damaging the coating topcoat to a certain extent, but does not improve its water resistance. In areas with high air humidity, the exterior wall substrate of the building is prone to alkali efflorescence, which can cause the above-mentioned exterior wall paint to age faster.

[0004] In the prior art, the waterproof property is mainly increased by adding some hydrophobic components to the exterior wall paint, but this only has a good waterproof effect when the paint film is intact. Once the paint film has cracks or damage, the overall waterproof property of the exterior wall paint is affected, especially in a rainy and humid environment, the coating is prone to water seepage, causing the wall to become damp and moldy, affecting the overall appearance of the building and the health of the residents; therefore, the present invention aims to solve the deficiencies of the existing exterior wall paint in terms of alkali resistance and waterproofness, by introducing organic silicon fluoride with good waterproof performance into the epoxy primer emulsion, the siloxane and epoxy groups in its structure can react with the alkali to form salt substances, effectively preventing the migration of salt and alkali; the quaternary ammonium salt can effectively play an antibacterial and mildew-proof role, meeting the market demand for high-performance exterior wall paint. Summary of the invention

[0005] In view of this, the object of the present invention is to provide a waterproof and alkali-resistant exterior wall paint and a preparation method thereof, which has excellent waterproofness and alkali resistance, as well as good mildew and antibacterial properties and a wide range of applications.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] A waterproof and alkali-resistant exterior wall paint comprises the following components in parts by weight: 100 parts of acrylic resin emulsion, 5-25 parts of organosilicon fluorine epoxy emulsion, 40-50 parts of tap water, 20-30 parts of heavy calcium carbonate, 8-15 parts of titanium dioxide, 2-5 parts of thickener, 0.5-1.2 parts of defoamer and 1-3 parts of film-forming aid.

[0008] The preparation method of the organosilicon fluorine epoxy emulsion is as follows: epoxy resin E51 and butyl acetate solvent are added to a reaction flask, stirred at a temperature of 35-50°C and a rotation speed of 200-300r / min until the epoxy resin is completely dissolved, and a structural formula The organic silicon fluoride dichlorobenzene intermediate, dibutyltin dilaurate and triethylamine are reacted at 50-70°C for 5-12 hours, filtered, washed with deionized water, and distilled under reduced pressure to obtain an organic silicon fluoride epoxy emulsion.

[0009] Preferably, the thickener is any one of hydroxyethyl cellulose, methyl cellulose or carboxymethyl cellulose.

[0010] Preferably, the film-forming aid is any one of dicyclopentenyloxyethyl acrylate, propylene glycol methyl ether acetate or dodecyl acetate.

[0011] Preferably, the mass ratio of epoxy resin E51, organosilicon fluorodichlorobenzene intermediate, dibutyltin dilaurate and triethylamine is 100:2-10:0.5-0.8:12-15.

[0012] Preferably, the preparation method of the organosilicon fluorodichlorobenzene intermediate is:

[0013] Step (1), under nitrogen atmosphere, add bis(4-chlorophenyl)amine and methanol to a reaction flask, stir evenly, add allyltrimethoxysilane, stir to react, after the reaction is completed, concentrate under reduced pressure, and purify by column chromatography to obtain a siloxane dichlorobenzene intermediate. The preparation reaction formula is as follows:

[0014]

[0015] Step (2), under nitrogen atmosphere, add siloxane dichlorobenzene intermediate and N, N-dimethylformamide to the reaction flask, stir evenly, add 1-bromo-1H, 1H, 2H, 2H-perfluorodecane, stir to react, after the reaction is completed, concentrate under reduced pressure, recrystallize from toluene, and obtain organosilicon fluoride dichlorobenzene intermediate. The preparation reaction formula is as follows:

[0016]

[0017] Preferably, in step (1), the mass ratio of bis(4-chlorophenyl)amine to allyltrimethoxysilane is 100:65-80.

[0018] Preferably, in step (1), the reaction temperature is 50-65° C. and the reaction time is 8-16 h.

[0019] Preferably, in step (2), the mass ratio of the siloxane dichlorobenzene intermediate to 1-bromo-1H,1H,2H,2H-perfluorodecane is 100:145-170.

[0020] Preferably, in step (2), the reaction temperature is 80-100° C. and the reaction time is 24-48 h.

[0021] Preferably, the preparation method of the waterproof and alkali-resistant exterior wall paint is: stirring acrylic resin emulsion, heavy calcium carbonate and titanium dioxide into a uniform slurry at 500-800r / min, adding a thickener, a film-forming aid and tap water, and dispersing at a high speed of 2000-2500r / min for 20-40min, adding an organosilicon fluorine epoxy emulsion and a defoaming agent, and stirring evenly to obtain a waterproof and alkali-resistant exterior wall paint.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The invention utilizes bis(4-chlorophenyl)amine and allyltrimethoxysilane to undergo Michael addition reaction to obtain a siloxane dichlorobenzene intermediate, which is then subjected to a quaternization reaction with 1-bromo-1H,1H,2H,2H-perfluorodecane to obtain an organic silicon fluoride dichlorobenzene intermediate, which is then substituted with a hydroxyl group in an epoxy resin E51 to obtain an organic silicon fluoride epoxy emulsion, which is finally uniformly mixed with an acrylic resin emulsion, heavy calcium carbonate and related additives to obtain a waterproof and alkali-resistant exterior wall paint.

[0024] (1) Organic fluorine, silicon and other low surface energy substances are introduced into the silicone fluorine epoxy emulsion. The CF bond energy is high and it is easy to embed into the polymer, blocking the channel for water molecules to migrate into the paint film. The organic fluorine is oriented outward on the surface of the paint film to form a hydrophobic layer. After hydrolysis, siloxane can produce chemical bonds with fillers to form a dense Si-O-Si three-dimensional cross-linked network structure, which makes the material have low surface free energy. At the same time, a very thin molecular layer is formed on the surface, thereby reducing the surface energy and preventing water droplets from staying on the surface, thereby achieving a waterproof effect.

[0025] (2) The organic silicon fluoride dichlorobenzene intermediate reacts with the hydroxyl group in the epoxy resin E51, retaining the epoxy group. The epoxy group can also react with alkali to form silicate, which can form hydrogen bonds in the primer to increase the sealing and adhesion, seal the mortar pores, and prevent the precipitation of alkali and salt. At the same time, the silanol formed after the hydrolysis of siloxane can cross-link with the carboxyl substance of the acrylic emulsion to form a tighter network structure, significantly improving the weather resistance and durability of the exterior wall paint. In addition, the paint emulsion has a small particle size and strong permeability. The introduction of organic silicon fluoride can not only form a dense coating on the material surface, but also prevent the migration of alkali and salt to the surface, providing a solid base for the exterior wall coating.

[0026] (3) The silicone fluoroepoxy emulsion contains quaternary ammonium salt groups, which mainly play a bactericidal role. It can be adsorbed on the surface of Escherichia coli and penetrate the cell wall through the attraction of positive charges and negatively charged substances in the cell membrane. It then combines with the cell membrane, changes the permeability of the Escherichia coli cell membrane, causes the substances in the bacteria to leak out, and eventually kills the Escherichia coli, achieving the purpose of antibacterial and anti-mildew. DETAILED DESCRIPTION

[0027] The following examples are provided to illustrate the present invention, but they are not to be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by technicians in the field according to the above content of the present invention still belong to the scope of protection of the present invention. Unless otherwise specified, the raw materials and reagents used in this application are all commercially available products, or can be prepared by known methods.

[0028] The defoamer used was defoamer NXZ, purchased from Guangzhou Yachuangxin Materials Co., Ltd.

[0029] Bis(4-chlorophenyl)amine, CAS number is 6962-04-5.

[0030] Allyltrimethoxysilane, CAS number is 2551-83-9.

[0031] 1-Bromo-1H,1H,2H,2H-perfluorodecane, CAS number is 21652-57-3.

[0032] Example 1

[0033] (1) Under a nitrogen atmosphere, 42 g of bis(4-chlorophenyl)amine and 275 mL of methanol were added to a reaction flask. After stirring, 31.5 g of allyltrimethoxysilane was added. The mixture was reacted at 55° C. for 12 h, concentrated under reduced pressure, and purified by column chromatography (dichloromethane / methanol=20:1) to obtain a siloxane dichlorobenzene intermediate.

[0034] (2) Under nitrogen atmosphere, 35 g of siloxane dichlorobenzene intermediate and 420 mL of N,N-dimethylformamide were added to a reaction flask, and after stirring, 56 g of 1-bromo-1H,1H,2H,2H-perfluorodecane was added, and the mixture was reacted at 90° C. for 32 h. The mixture was concentrated under reduced pressure and recrystallized from toluene to obtain an organosilicone fluorodichlorobenzene intermediate.

[0035] (3) Add 100 g of epoxy resin E51 and 70 mL of butyl acetate solvent into a reaction flask, stir at 45 °C and 250 r / min until the epoxy resin is completely dissolved, add 2 g of organosilicon fluorodichlorobenzene intermediate, 0.6 g of dibutyltin dilaurate and 14 g of triethylamine, react at 60 °C for 10 h, filter, wash with deionized water, and distill under reduced pressure to obtain an organosilicon fluoroepoxy emulsion.

[0036] (4) 100 g of acrylic resin emulsion, 25 g of heavy calcium carbonate, and 12 g of titanium dioxide were stirred at 600 r / min to form a uniform slurry, 4 g of hydroxyethyl cellulose, 2 g of dicyclopentenyloxyethyl acrylate, and 45 g of tap water were added, and the mixture was dispersed at a high speed of 2200 / min for 30 min. 5 g of organosilicon fluorine epoxy emulsion and 0.9 g of defoamer NXZ were added, and the mixture was stirred evenly to obtain a waterproof and alkali-resistant exterior wall paint.

[0037] Example 2

[0038] (1) Under nitrogen atmosphere, add 80 g of bis(4-chlorophenyl)amine and 400 mL of methanol to a reaction flask, stir evenly, then add 52 g of allyltrimethoxysilane, and react at 65° C. for 8 h. Concentrate under reduced pressure, and purify by column chromatography (dichloromethane / methanol=20:1) to obtain a siloxane dichlorobenzene intermediate.

[0039] (2) Under nitrogen atmosphere, 75 g of siloxane dichlorobenzene intermediate and 750 mL of N,N-dimethylformamide were added to a reaction flask. After stirring, 108.75 g of 1-bromo-1H,1H,2H,2H-perfluorodecane was added. The mixture was reacted at 100° C. for 24 h, concentrated under reduced pressure, and recrystallized from toluene to obtain an organosilicone fluorodichlorobenzene intermediate.

[0040] (3) Add 100 g of epoxy resin E51 and 60 mL of butyl acetate solvent into a reaction flask, stir at 50 °C and 300 r / min until the epoxy resin is completely dissolved, add 4 g of organosilicon fluorodichlorobenzene intermediate, 0.5 g of dibutyltin dilaurate and 12 g of triethylamine, react at 70 °C for 5 h, filter, wash with deionized water, and distill under reduced pressure to obtain an organosilicon fluoroepoxy emulsion.

[0041] (4) 100 g of acrylic resin emulsion, 20 g of heavy calcium carbonate, and 8 g of titanium dioxide were stirred at 800 r / min to form a uniform slurry, 2 g of methyl cellulose, 1 g of propylene glycol methyl ether acetate, and 40 g of tap water were added, and the mixture was dispersed at a high speed of 2500 / min for 20 min. 10 g of organosilicon fluorine epoxy emulsion and 0.5 g of defoamer NXZ were added, and the mixture was stirred evenly to obtain a waterproof and alkali-resistant exterior wall paint.

[0042] Example 3

[0043] (1) Under nitrogen atmosphere, 30 g of bis(4-chlorophenyl)amine and 240 mL of methanol were added to a reaction flask. After stirring, 24 g of allyltrimethoxysilane was added. The mixture was reacted at 50° C. for 16 h, concentrated under reduced pressure, and purified by column chromatography (dichloromethane / methanol=20:1) to obtain a siloxane dichlorobenzene intermediate.

[0044] (2) Under nitrogen atmosphere, 25 g of siloxane dichlorobenzene intermediate and 375 mL of N,N-dimethylformamide were added to a reaction flask, stirred evenly, and then 42.5 g of 1-bromo-1H,1H,2H,2H-perfluorodecane was added. The mixture was reacted at 80° C. for 48 h, concentrated under reduced pressure, and recrystallized from toluene to obtain an organosilicone fluorodichlorobenzene intermediate.

[0045] (3) Add 100 g of epoxy resin E51 and 80 mL of butyl acetate solvent into a reaction flask, stir at a temperature of 35° C. and a rotation speed of 200 r / min until the epoxy resin is completely dissolved, add 6 g of organosilicon fluorodichlorobenzene intermediate, 0.8 g of dibutyltin dilaurate and 15 g of triethylamine, react at 50° C. for 12 h, filter, wash with deionized water, and distill under reduced pressure to obtain an organosilicon fluoroepoxy emulsion.

[0046] (4) 100 g of acrylic resin emulsion, 30 g of heavy calcium carbonate, and 15 g of titanium dioxide were stirred at 500 r / min to form a uniform slurry, 5 g of carboxymethyl cellulose, 3 g of dodecyl alcohol, and 50 g of tap water were added, and the mixture was dispersed at a high speed of 2000 r / min for 40 min. 15 g of organosilicon fluorine epoxy emulsion and 1.2 g of defoamer NXZ were added, and the mixture was stirred evenly to obtain a waterproof and alkali-resistant exterior wall paint.

[0047] Example 4

[0048] (1) Under a nitrogen atmosphere, 65 g of bis(4-chlorophenyl)amine and 468 mL of methanol were added to a reaction flask. After stirring, 49.5 g of allyltrimethoxysilane was added. The mixture was reacted at 60° C. for 15 h, concentrated under reduced pressure, and purified by column chromatography (dichloromethane / methanol=20:1) to obtain a siloxane dichlorobenzene intermediate.

[0049] (2) Under nitrogen atmosphere, 60 g of siloxane dichlorobenzene intermediate and 750 mL of N,N-dimethylformamide were added to a reaction flask, and after stirring, 95 g of 1-bromo-1H,1H,2H,2H-perfluorodecane was added, and the mixture was reacted at 95° C. for 40 h. The mixture was concentrated under reduced pressure and recrystallized from toluene to obtain an organosilicone fluorodichlorobenzene intermediate.

[0050] (3) Add 100 g of epoxy resin E51 and 75 mL of butyl acetate solvent into a reaction flask, stir at 40 °C and 280 r / min until the epoxy resin is completely dissolved, add 8 g of organosilicon fluorodichlorobenzene intermediate, 0.6 g of dibutyltin dilaurate and 13 g of triethylamine, react at 65 °C for 10 h, filter, wash with deionized water, and distill under reduced pressure to obtain an organosilicon fluoroepoxy emulsion.

[0051] (4) 100 g of acrylic resin emulsion, 26 g of heavy calcium carbonate, and 14 g of titanium dioxide were stirred at 650 r / min to form a uniform slurry, 4 g of hydroxyethyl cellulose, 3 g of dicyclopentenyloxyethyl acrylate, and 48 g of tap water were added, and the mixture was dispersed at a high speed at 2400 r / min for 35 min. 20 g of silicone fluorine epoxy emulsion and 0.8 g of defoamer NXZ were added, and the mixture was stirred evenly to obtain a waterproof and alkali-resistant exterior wall paint.

[0052] Example 5

[0053] (1) Under nitrogen atmosphere, 20 g of bis(4-chlorophenyl)amine and 115 mL of methanol were added to a reaction flask. After stirring, 15 g of allyltrimethoxysilane was added. The mixture was reacted at 65° C. for 15 h, concentrated under reduced pressure, and purified by column chromatography (dichloromethane / methanol=20:1) to obtain a siloxane dichlorobenzene intermediate.

[0054] (2) Under nitrogen atmosphere, 15 g of siloxane dichlorobenzene intermediate and 180 mL of N,N-dimethylformamide were added to a reaction flask, stirred evenly, and then 23.7 g of 1-bromo-1H,1H,2H,2H-perfluorodecane was added. The mixture was reacted at 95° C. for 32 h, concentrated under reduced pressure, and recrystallized from toluene to obtain an organosilicone fluorodichlorobenzene intermediate.

[0055] (3) Add 100 g of epoxy resin E51 and 65 mL of butyl acetate solvent into a reaction flask, stir at 45 °C and 240 r / min until the epoxy resin is completely dissolved, add 10 g of organosilicon fluorodichlorobenzene intermediate, 0.75 g of dibutyltin dilaurate and 13 g of triethylamine, react at 65 °C for 12 h, filter, wash with deionized water, and distill under reduced pressure to obtain an organosilicon fluoroepoxy emulsion.

[0056] (4) 100 g of acrylic resin emulsion, 30 g of heavy calcium carbonate, and 10 g of titanium dioxide were stirred at 750 r / min to form a uniform slurry, 5 g of methyl cellulose, 2 g of propylene glycol methyl ether acetate, and 45 g of tap water were added, and the mixture was dispersed at a high speed of 2350 r / min for 35 min. 25 g of silicone fluorine epoxy emulsion and 1 g of defoamer NXZ were added, and the mixture was stirred evenly to obtain a waterproof and alkali-resistant exterior wall paint.

[0057] Comparative Example 1

[0058] (1) 100 g of epoxy resin E51 and 70 mL of butyl acetate solvent were added to a reaction flask, and stirred at a temperature of 45° C. and a rotation speed of 250 r / min until the epoxy resin was completely dissolved. 2 g of siloxane dichlorobenzene intermediate (prepared in Example 1), 0.6 g of dibutyltin dilaurate and 14 g of triethylamine were added, and the mixture was reacted at 60° C. for 10 h. The mixture was filtered, washed with deionized water, and distilled under reduced pressure to obtain a siloxane epoxy emulsion.

[0059] (2) 100 g of acrylic resin emulsion, 25 g of heavy calcium carbonate, and 12 g of titanium dioxide were stirred at 600 r / min to form a uniform slurry, 4 g of hydroxyethyl cellulose, 2 g of dicyclopentenyloxyethyl acrylate, and 45 g of tap water were added, and the mixture was dispersed at a high speed of 2200 / min for 30 min. 5 g of siloxane epoxy emulsion and 0.9 g of defoamer NXZ were added, and the mixture was stirred evenly to obtain an exterior wall paint.

[0060] Comparative Example 2

[0061] 100g acrylic resin emulsion, 25g heavy calcium carbonate, and 12g titanium dioxide were stirred at 600r / min to form a uniform slurry, 4g hydroxyethyl cellulose, 2g dicyclopentenyloxyethyl acrylate and 45g tap water were added, and the mixture was dispersed at a high speed of 2200 / min for 30min. 5g epoxy resin E51 emulsion and 0.9g defoamer NXZ were added, and the mixture was stirred evenly to obtain an exterior wall paint.

[0062] Preparation of paint film: Apply the prepared exterior wall paint evenly on the polytetrafluoroethylene plate twice, with a paint film thickness of 0.3mm. Keep the room clean and dust-free, dry naturally at room temperature for 48 hours, and after the water evaporates, dry at 80℃ for 3 hours to form a paint film.

[0063] Surface contact angle test: Use a contact angle meter to test, drop 5μL of water on the surface of the paint film, measure the contact angle of the paint film to water, select 5 different points for each sample for measurement, and take the average value as the contact angle of the paint film surface.

[0064] Water absorption test: Cut the paint film into small pieces of 80mm×80mm and weigh its initial mass as M 0, soak it in water at room temperature for 48 hours, take it out, absorb the water on the surface with filter paper, and weigh its mass as M 1 The water absorption rate of the paint film is calculated as follows: Water absorption rate = (M 1 -M 0 ) / M 0 ×100%.

[0065] Table 1 Waterproof performance test

[0066] Contact angle (°) Water absorption (%) Example 1 103.6 6.23 Example 2 115.3 4.12 Example 3 124.0 1.98 Example 4 132.8 1.42 Example 5 135.2 1.30 Comparative Example 1 81.5 10.01 Comparative Example 2 76.4 15.37

[0067] It can be seen from the test results in Table 1 above that with the increase of the content of organic silicon fluorine epoxy emulsion, the waterproof performance of the exterior wall paint gradually increases. The water absorption rate in Example 5 is only 1.42%, and the contact angle is 135.2°, which has good waterproof performance. This is because organic silicon fluorine epoxy emulsion introduces low surface energy substances such as organic fluorine and silicon, and the CF bond energy is high, which is easy to embed into the polymer, blocking the channel for water molecules to migrate to the inside of the paint film, and the organic fluorine is arranged outwardly on the surface of the paint film to form a hydrophobic layer; after hydrolysis, siloxane can produce chemical bonding with fillers, etc., to form a dense Si-O-Si three-dimensional cross-linked network structure, so that the material has low surface free energy, and at the same time forms a very thin molecular layer on the surface, thereby reducing the surface energy, so that water drops cannot stay on the surface, thereby achieving a waterproof effect. Comparative Example 1 does not contain organic fluorine, and its waterproof performance is general; Comparative Example 2 does not contain organic silicon fluorine, and its waterproof performance is poor.

[0068] Alkali resistance test: refer to GB / T 9274-1988 standard, immerse 2 / 3 of the height of the paint film in a 5% NaOH solution, observe the changes of the paint film every 2 hours, and stop observing when bubbles, peeling or serious discoloration appear on the paint film. The time from the start of the test to this time is the alkali resistance time of the paint film.

[0069] Table 2 Alkali resistance test

[0070] Alkali resistance (h) Example 1 36 Example 2 48 Example 3 64 Example 4 70 Example 5 72 Comparative Example 1 30 Comparative Example 2 24

[0071] It can be seen from the test results in Table 2 above that with the increase of the content of organic silicon fluorine epoxy emulsion, the alkali resistance of the exterior wall paint gradually increases. This is because the organic silicon fluorine dichlorobenzene intermediate reacts with the hydroxyl group in the epoxy resin E51 to retain the epoxy group, and the epoxy group can also react with the alkali to form a silicate, which can form hydrogen bonds in the primer to increase the sealing and adhesion, seal the mortar pores, and prevent the precipitation of alkali and salt; at the same time, the silanol formed after the hydrolysis of siloxane can cross-link with the carboxyl substance of the acrylic emulsion to form a tighter network structure, which significantly improves the weather resistance and durability of the exterior wall paint; in addition, the paint emulsion has a small particle size and strong permeability. The introduction of organic silicon fluorine forms a dense coating on the surface of the material, which prevents the migration of alkali and salt to the surface, providing a solid base for the exterior wall coating.

[0072] Antibacterial performance test: Escherichia coli was inoculated into beef extract peptone for culture activation, and then the activated Escherichia coli suspension was added to a sterile culture dish, culture medium and phosphate buffer solution were added, and cultured at 37°C for 24 hours. The prepared paint film was added as the test group, and no paint film was added as the blank group. After culture, the number of viable bacteria in the test sample and the blank sample was determined respectively, and the inhibition rate was calculated; inhibition rate = (number of viable bacteria in the blank group - number of viable bacteria in the experimental group) / number of viable bacteria in the blank group × 100%.

[0073] Inhibition zone test: Pipette 0.05 mL of 1×10 7 CFU / mL of Escherichia coli suspension was added to the culture dish, beef extract peptone agar medium was added and shaken evenly, then the prepared paint film was added, placed on the solid culture medium, and cultured in an incubator at a constant temperature of 37°C for 24 hours. After culture, the diameter of the inhibition zone was measured and the average value was taken.

[0074] Table 3 Antibacterial performance test

[0075]

[0076] Generally speaking, the larger the diameter of the inhibition zone, the more obvious the antibacterial effect; from the test results in Table 3 above, it can be seen that with the increase in the content of the organosilicon fluorine epoxy emulsion, the inhibitory effect of the exterior wall paint on Escherichia coli is significantly enhanced. The diameter of the inhibition zone in Example 5 reaches 23.4 mm, and the inhibition rate reaches 99.9%. This is because the organosilicon fluorine epoxy emulsion contains quaternary ammonium salt groups, which mainly play a bactericidal role, can be adsorbed on the surface of Escherichia coli, and through the positive charge and the negative charge substances in the cell membrane, it is attracted to penetrate the cell wall, and then combined with the cell membrane, changing the permeability of the Escherichia coli cell membrane, causing the substances in the bacteria to leak out, and finally killing the Escherichia coli, achieving the purpose of antibacterial and mildew prevention; while Comparative Examples 1 and 2 do not contain quaternary ammonium salt structures and have no antibacterial effect.

[0077] The above contents are merely examples and explanations of the concept of the present invention. The technicians in this technical field may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the concept of the invention or exceed the scope defined by the claims, they should all fall within the protection scope of the present invention.

Claims

1. A waterproof and alkali-resistant exterior wall paint, characterized in that: The waterproof and alkali-resistant exterior wall paint comprises the following components in parts by weight: 100 parts of acrylic resin emulsion, 5-25 parts of organosilicon fluorine epoxy emulsion, 40-50 parts of tap water, 20-30 parts of heavy calcium carbonate, 8-15 parts of titanium dioxide, 2-5 parts of thickener, 0.5-1.2 parts of defoamer and 1-3 parts of film-forming aid; The preparation method of the organosilicon fluorine epoxy emulsion is as follows: epoxy resin E51 and butyl acetate solvent are added to a reaction flask, stirred at a temperature of 35-50° C. and a rotation speed of 200-300 r / min until the epoxy resin is completely dissolved, and a fluorine-containing emulsion having a structural formula of The organic silicon fluoride dichlorobenzene intermediate, dibutyltin dilaurate and triethylamine are reacted at 50-70°C for 5-12 hours, filtered, washed with deionized water, and distilled under reduced pressure to obtain an organic silicon fluoride epoxy emulsion.

2. The waterproof and alkali-resistant exterior wall paint according to claim 1, characterized in that: The thickener is any one of hydroxyethyl cellulose, methyl cellulose or carboxymethyl cellulose.

3. The waterproof and alkali-resistant exterior wall paint according to claim 1, characterized in that: The film-forming aid is any one of dicyclopentenyloxyethyl acrylate, propylene glycol methyl ether acetate or dodecyl acetate.

4. The waterproof and alkali-resistant exterior wall paint according to claim 1, characterized in that: The mass ratio of the epoxy resin E51, the organic silicon fluorodichlorobenzene intermediate, the dibutyltin dilaurate and the triethylamine is 100:2-10:0.5-0.8:12-15.

5. The waterproof and alkali-resistant exterior wall paint according to claim 1, characterized in that: The preparation method of the organosilicon fluorine dichlorobenzene intermediate is: Step (1), under a nitrogen atmosphere, add bis(4-chlorophenyl)amine and methanol to a reaction flask, stir evenly, add allyltrimethoxysilane, stir to react, and after the reaction is completed, concentrate under reduced pressure, and purify by column chromatography to obtain a siloxane dichlorobenzene intermediate; Step (2), under nitrogen atmosphere, add siloxane dichlorobenzene intermediate and N, N-dimethylformamide to a reaction flask, stir evenly, add 1-bromo-1H,1H,2H,2H-perfluorodecane, stir to react, after the reaction is completed, concentrate under reduced pressure, and recrystallize from toluene to obtain an organosilicon fluoride dichlorobenzene intermediate.

6. The waterproof and alkali-resistant exterior wall paint according to claim 5, characterized in that: In the step (1), the mass ratio of bis(4-chlorophenyl)amine to allyltrimethoxysilane is 100:65-80.

7. The waterproof and alkali-resistant exterior wall paint according to claim 5, characterized in that: In the step (1), the reaction temperature is 50-65° C. and the reaction time is 8-16 h.

8. The waterproof and alkali-resistant exterior wall paint according to claim 5, characterized in that: In the step (2), the mass ratio of the siloxane dichlorobenzene intermediate to 1-bromo-1H,1H,2H,2H-perfluorodecane is 100:145-170.

9. The waterproof and alkali-resistant exterior wall paint according to claim 5, characterized in that: In the step (2), the reaction temperature is 80-100° C. and the reaction time is 24-48 hours.

10. A method for preparing the waterproof and alkali-resistant exterior wall paint according to any one of claims 1 to 9, characterized in that: The preparation method comprises the following steps: stirring acrylic resin emulsion, heavy calcium carbonate and titanium dioxide at 500-800 r / min to form a uniform slurry, adding a thickener, a film-forming aid and tap water, dispersing at a high speed at 2000-2500 r / min for 20-40 min, adding an organosilicon fluorine epoxy emulsion and a defoamer, stirring evenly, and obtaining a waterproof and alkali-resistant exterior wall paint.

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