Waterproof decorative integrated reflective thermal insulation waterborne polyurethane exterior wall coating and preparation method thereof

Abstract

The application relates to the field of coatings, in particular to a waterproof and decorative integrated reflective heat-insulating water-based polyurethane outer wall coating and a preparation method thereof. The waterproof and decorative integrated reflective heat-insulating water-based polyurethane outer wall coating is prepared from the following raw materials in percentage by mass: water-based polyurethane emulsion 30-40%, filler 20-30%, modified particle 8-12%, reflective heat-insulating color paste 3-6%, cellulose ether 0.3-0.5%, pH regulator 0.2-0.3%, dispersant 0.3-0.5%, wetting agent 0.1-0.2%, defoaming agent 0.3-0.5%, rheological aid 0.3-0.5%, anti-freezing agent 0.5-1%, film-forming aid 2-2.5%, mildew-proof and bacteria-proof agent 0.3-0.6%, and deionized water in the rest. The water-based polyurethane outer wall coating prepared through the application not only has excellent decorative and waterproof integrated performance, but also has good corrosion resistance, stain resistance, aging resistance and reflective heat-insulating performance, thereby meeting the multifunctional performance requirement of the existing consumers for the outer wall coating.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of coatings, in particular to a waterproof and decorative integrated reflective thermal insulation waterborne polyurethane exterior wall coating and a preparation method thereof. BACKGROUND

[0002] In recent years, with the intensification of global energy crisis and the improvement of environmental awareness, developing high-performance and environmentally friendly building coatings has become an important development direction of the coating industry. Waterborne polyurethane coatings gradually replace traditional solvent-based coatings due to their excellent physical and chemical properties, such as good flexibility, chemical resistance and environmental protection characteristics, and are widely used in building exterior walls, steel structures, public facilities and other fields.

[0003] Reflective thermal insulation coatings, as a kind of energy-saving materials, can effectively reflect infrared and visible light in sunlight, reduce the heat absorbed by the building surface, and thus reduce the indoor temperature and save air conditioning energy consumption. This kind of coating not only helps to improve the energy efficiency of buildings, but also improves the comfort of living and working environment. However, traditional water-based coatings and waterproof coatings are different types of products, and in the field of building construction, they are constructed in different processes such as waterproofing, decoration, etc. Water-based coatings for decoration do not have the performance of waterproofing, energy saving and solar reflection and thermal insulation, so the usual construction steps are to apply waterproof coating to the exterior wall and then apply water-based coating for exterior wall decoration, which is relatively complex.

[0004] Therefore, in order to effectively solve the above problems, the present application provides a waterproof and decorative integrated reflective thermal insulation waterborne polyurethane exterior wall coating and a preparation method thereof. The waterborne polyurethane exterior wall coating finally prepared by the present application not only has excellent decorative and waterproof integrated performance, but also has good corrosion resistance, stain resistance, aging resistance and reflective thermal insulation performance, thereby meeting the multifunctional performance requirements of consumers for exterior wall coatings and avoiding the step-by-step construction problem of existing waterproof coatings and decorative coatings, reducing the construction operation, and thus having a very excellent application prospect. SUMMARY

[0005] In order to solve the above problems, the present application provides a waterproof and decorative integrated reflective thermal insulation waterborne polyurethane exterior wall coating. The raw materials are as follows in terms of mass percentage: waterborne polyurethane emulsion 30-40%, filler 20-30%, modified particles 8-12%, reflective thermal insulation color paste 3-6%, cellulose ether 0.3-0.5%, pH adjuster 0.2-0.3%, dispersant 0.3-0.5%, wetting agent 0.1-0.2%, defoaming agent 0.3-0.5%, rheological aid 0.3-0.5%, anti-freezing agent 0.5-1%, film-forming aid 2-2.5%, mildew and bacteria resistant agent 0.3-0.6%, and deionized water to make up the balance.

[0006] As a preferred solution, the solid content of the water-based polyurethane emulsion is 30-50%.

[0007] As a preferred solution, the solid content of the water-based polyurethane emulsion is 35-45%.

[0008] As a preferred solution, the viscosity of the water-based polyurethane emulsion is 300-2000 mPa·s at 25℃.

[0009] As a preferred solution, the viscosity of the water-based polyurethane emulsion is 800-1400 mPa·s at 25℃.

[0010] As a preferred solution, the filler is at least one of barium sulfate, calcium carbonate, talc, kaolin and diatomite.

[0011] As a preferred solution, the filler is barium sulfate or talc.

[0012] As a preferred solution, the average particle size of the filler is 0.1-1 μm.

[0013] As a preferred solution, the average particle size of the filler is 0.2-0.6 μm.

[0014] As a preferred solution, the mass ratio of the water-based polyurethane emulsion, the filler and the modified particle is (32-38):(22-26):(10-12).

[0015] As a preferred solution, the mass ratio of the water-based polyurethane emulsion, the filler and the modified particle is (34-36):(23-25):(10-11).

[0016] As a preferred solution, the mass ratio of the water-based polyurethane emulsion, the filler and the modified particle is 35:24:10.5.

[0017] As a preferred solution, the modified particle is modified titanium dioxide.

[0018] As a preferred scheme, the preparation method of the modified titanium dioxide specifically comprises the following steps: S1: titanium dioxide and zinc chloride are mixed and added into a DMF solution, succinic anhydride is added, the temperature is raised to 70-75℃ and kept for 3-3.5h, after the reaction is completed, diethylamine is added to adjust the pH to 7.5-8, then dodecyl dimethyl benzyl ammonium bromide, polyethylene glycol 2000 and terephthalic acid are added, the temperature is raised to 110-120℃ and kept for 24-30h, the product is filtered, washed with DMF for 2-3 times, and after drying, pre-reaction particles are obtained; S2: the pre-reaction particles, 1,4-diaminobenzene, p-aminobenzoic acid and 2-methyl imidazole are mixed and added into DMF, stirred at 70-80℃ and a stirring speed of 200-300rpm for 16-20h; S3: then the temperature is raised to 100-110℃, kept for 14-16h, after the reaction is completed, the product is filtered, washed with DMF for 2-3 times, vacuum dried at 80-90℃ for 6-8h, and after completion, the modified titanium dioxide is obtained.

[0019] As a preferred scheme, the mass ratio of the titanium dioxide, zinc chloride and succinic anhydride is (2.3-2.6):(1.8-2.1):(1-1.2).

[0020] As a preferred scheme, the mass ratio of the titanium dioxide, dodecyl dimethyl benzyl ammonium bromide, polyethylene glycol 2000 and terephthalic acid is (2.3-2.6):(0.2-0.25):(0.3-0.4):(2-2.5).

[0021] As a preferred scheme, the mass ratio of the pre-reaction particles, 1,4-diaminobenzene, p-aminobenzoic acid and 2-methyl imidazole is (2.1-2.4):(0.6-0.8):(0.2-0.4):(0.1-0.2).

[0022] As a preferred scheme, the average particle size of the titanium dioxide is 5-10nm.

[0023] As a preferred scheme, the average particle size of the modified titanium dioxide is 500-600nm.

[0024] The modified titanium dioxide prepared in the present application can effectively improve the reflective heat insulation performance of the exterior wall coating, and at the same time maintain excellent corrosion resistance and aging resistance. The modified titanium dioxide can form a composite particle with modified titanium dioxide as the surface particle and a microporous skeleton as the main body in the interior by constructing a multi-composite skeleton. The composite skeleton structure of the modified particle greatly improves the refractive index of the titanium dioxide particle. At the same time, the skeleton structure greatly enhances the electronic vibration effect of the surface modified titanium dioxide in the infrared light wave band, and enriches the electronic surface aggregation, further enhances the reflection efficiency of the modified titanium dioxide to near-infrared light, greatly reduces the absorption of heat, and the more complex particle skeleton structure enhances the light scattering effect of light waves on the surface and inside of the coating, greatly increases the length of the light penetration path, reduces the light scattering energy penetrating into the interior of the coating, thereby making the exterior wall coating obtain excellent reflective heat insulation performance.

[0025] On the other hand, the modified titanium dioxide can form a good heterojunction structure under the premise of absorbing a small amount of light energy. The structure can greatly enhance the aggregation degree and stability of the oxidized molecules on the surface of the particle, thereby maintaining good resistance of active molecules and organic molecules during long-term use, and thereby obtaining excellent corrosion resistance, stain resistance and aging resistance and other properties. The modified titanium dioxide can enhance the mutual connection with the polyurethane resin system through the action of the groups after surface modification, thereby greatly enhancing the stability of the modified titanium dioxide in the system, greatly reducing the micropore porosity of the modified particles in the system, reducing the large gaps formed by the pore series, thereby greatly enhancing the barrier effect of the exterior wall coating to moisture and active molecules, thereby maintaining excellent corrosion resistance and other properties.

[0026] As a preferred scheme, the preparation method of the reflective heat insulation color paste specifically comprises the following steps: S1: adding deionized water in a high-speed mixer, then sequentially adding polycarboxylic acid sodium salt, cocamide propyl betaine, defoaming agent BYK-066N and reflective heat insulation pigment, stirring at a speed of 600-800 rpm for 15-20 min to ensure uniform dispersion, then adding hydroxyethyl cellulose and sodium hydroxide solution to adjust the pH to 8-8.5, then increasing the speed to 1200-1500 rpm for high-speed dispersion for 40-60 min to ensure sufficient dispersion of the reflective heat insulation pigment, forming a stable pre-dispersion liquid; S2: transferring the pre-dispersion liquid into a sand mill and sand milling for 80-100 min, then transferring into a mixing kettle and adding polyurethane rheological additives, propylene glycol and thienimidazole, adjusting the stirring speed to 650-750 rpm, stirring for 20-30 min, then filtering the mixed product through a 200-300 mesh screen to remove large particle impurities, and sealing and storing.

[0027] As a preferred scheme, the reflective heat insulation pigment is at least one of titanium white, cobalt-chromium blue, cobalt blue, cobalt green, iron-chromium black, titanium-chromium brown, zinc-iron yellow, and titanium-nickel yellow.

[0028] As a preferred scheme, the mass ratio of the sodium polycarboxylate, cocamidopropyl betaine, reflective heat insulation pigment, hydroxyethyl cellulose, and sodium polyacrylate is (2~3):(0.5~1):(25~28):(2.5~3):(0.4~0.6).

[0029] As a preferred scheme, the cellulose ether is a combination of hydroxyethyl cellulose and methyl hydroxyethyl cellulose.

[0030] As a preferred scheme, the mass ratio of the hydroxyethyl cellulose and methyl hydroxyethyl cellulose is (3~4):(1~1.2).

[0031] As a preferred scheme, the pH adjuster is at least one of ammonia water, triethanolamine, sodium hydroxide, 2-amino-2-methyl-1-propanol, and triethylamine.

[0032] As a preferred scheme, the pH adjuster is ammonia water or sodium hydroxide.

[0033] As a preferred scheme, the dispersant is at least one of sodium polycarboxylate, ammonium polycarboxylate, lauryl alcohol polyoxyethylene ether, cetyl stearyl alcohol polyoxyethylene ether, and cocobetaine.

[0034] As a preferred scheme, the dispersant is cocobetaine.

[0035] As a preferred scheme, the wetting agent is polyether-modified polysiloxane or polysiloxane.

[0036] As a preferred scheme, the wetting agent is polysiloxane.

[0037] As a preferred scheme, the defoaming agent is at least one of BYK-024, BYK-025, BYK-088, BYK-1790, and BYK-066N.

[0038] As a preferred scheme, the defoaming agent is BYK-066N.

[0039] As a preferred scheme, the rheological aid is a combination of acrylic and polyurethane.

[0040] As a preferred scheme, the mass ratio of the acrylic and polyurethane is (2~2.5):(5.5~6).

[0041] As a preferred scheme, the mass ratio of the acrylic and the polyurethane is 2.5:5.8.

[0042] As a preferred scheme, the anti-freezing agent is at least one of polyethylene glycol, propylene glycol, glycerol, diethylene glycol, and a non-ionic surfactant.

[0043] As a preferred scheme, the anti-freezing agent is a combination of propylene glycol and a non-ionic.

[0044] As a preferred scheme, the mass ratio of the propylene glycol and the diethylene glycol is (3~4):(1.2~1.5).

[0045] As a preferred scheme, the mass ratio of the propylene glycol and the diethylene glycol is 3.6:1.4.

[0046] As a preferred scheme, the film-forming aid is a combination of dodecanol ester and hexadecanol ester.

[0047] As a preferred scheme, the mass ratio of the dodecanol ester and the hexadecanol ester is (6~8):(1.5~2.5).

[0048] As a preferred scheme, the anti-mold and anti-bacterial agent is at least one of thiabendazole, methyldithiocyanomethane, zinc pyrithione, benzisothiazolinone, and methylisothiazolinone.

[0049] As a preferred scheme, the anti-mold and anti-bacterial agent is a combination of benzisothiazolinone and methylisothiazolinone.

[0050] As a preferred scheme, the mass ratio of the benzisothiazolinone and the methylisothiazolinone is (1.5~2):(0.5~0.8).

[0051] The second aspect of the application provides a preparation method of the waterproof and decorative integrated reflective thermal insulation water-based polyurethane exterior wall coating, which specifically comprises the following steps: S1: adding deionized water in a mixing container, sequentially adding fillers, modified particles and reflective thermal insulation color paste, continuously stirring for 30-40 min to ensure uniform dispersion, adding cellulose ether, pH adjuster, dispersing agent, wetting agent and defoaming agent, continuing to stir for 15-20 min, increasing the stirring speed to 1200-1500 rpm, and maintaining high-speed dispersion for 30-60 min to ensure sufficient dispersion and form a stable pre-dispersion liquid; S2: then slowly adding water-based polyurethane emulsion while stirring at a speed of 400-500 rpm to ensure uniform mixing; S3: adding rheological additives, anti-freezing agents, film-forming additives and mildew-proof and bacteria-proof agents, adjusting the stirring speed to 650-750 rpm, and stirring for 20-30 min, then filtering the mixed product through a 100-200 mesh screen to remove large particle impurities, and then packaging the filtered coating into clean and dry containers for sealing and storage.

[0052] The application has the following beneficial effects:

[0053] 1. The waterproof and decorative integrated reflective thermal insulation water-based polyurethane exterior wall coating provided in the application not only has excellent decorative and waterproof integrated performance, but also has good corrosion resistance, stain resistance, aging resistance and reflective thermal insulation performance, thereby meeting the multifunctional performance requirements of consumers for exterior wall coatings and avoiding the step-by-step construction problem of existing waterproof coatings and decorative coatings, reducing the construction operation, and thus having a very excellent application prospect.

[0054] 2. The waterproof and decorative integrated reflective thermal insulation water-based polyurethane exterior wall coating provided in the application, the modified titanium dioxide can form composite particles with modified titanium dioxide as surface particles and microporous skeleton as the main body in the interior through the construction of a multi-composite skeleton structure. The composite skeleton structure of the modified particles greatly improves the refractive index of titanium dioxide particles, and the skeleton structure greatly enhances the electronic vibration effect of the surface modified titanium dioxide in the infrared light wave band, and enriches the surface aggregation of electrons, further enhances the reflection efficiency of the modified titanium dioxide to near-infrared light, greatly reduces the absorption of heat, and the more complex particle skeleton structure enhances the light scattering effect of light waves on the surface and inside of the coating, greatly increases the length of the light penetration path, reduces the light scattering energy penetrating into the interior of the coating, and thus the exterior wall coating has excellent reflective thermal insulation performance.

[0055] 3、The waterproof decorative integrated reflective thermal insulation waterborne polyurethane exterior wall paint provided in the application can form a good heterojunction structure on the premise of absorbing a small amount of light energy, the structure can greatly enhance the aggregation degree and stability of oxidized molecules on the particle surface, and can maintain good impedance of active molecules and organic molecules during long-term use, thereby obtaining excellent corrosion resistance and aging resistance. DETAILED DESCRIPTION

[0056] The technical solutions in the above summary of the application will be further described and demonstrated in the form of specific embodiments. The following examples are only actual examples for illustrating and explaining the content of the technical solutions in the specification, and should not limit the scope of the claims of the application. Any technical product based on the technical solutions described in the summary of the application should be covered in the scope of the application.

[0057] In the following examples, unless otherwise specified, the raw materials are commercially available products or can be prepared by methods well known to those skilled in the art.

[0058] Example 1

[0059] Example 1 provides a waterproof decorative integrated reflective thermal insulation waterborne polyurethane exterior wall paint. The raw materials are as follows in terms of mass percentage: waterborne polyurethane emulsion 40%, filler 30%, modified particle 15%, reflective thermal insulation color paste 4.5%, cellulose ether 0.4%, pH adjuster 0.22%, dispersant 0.41%, wetting agent 0.16%, defoaming agent 0.35%, rheological aid 0.44%, anti-freezing agent 0.8%, film-forming aid 2.3%, mildew and bacteria resistant agent 0.32%, and deionized water to make up the balance.

[0060] The solid content of the waterborne polyurethane emulsion is 40%, and the viscosity is 1200 mPa·s at 25°C, which is purchased from the product of Bayhydrol XP 2678 sold by Covestro Company in Germany.

[0061] The filler is superfine barium sulfate with an average particle size of 0.25 μm.

[0062] The modified particles are modified titanium dioxide; the preparation method of the modified titanium dioxide specifically comprises the following steps, in terms of mass parts: S1: 2.4 parts of titanium dioxide and 2 parts of zinc chloride are mixed and added into 120 parts of DMF solution, 1.1 parts of succinic anhydride are added, the temperature is increased to 75°C and kept for 3 hours, after the reaction is completed, diethylamine is added to adjust the pH to 7.5, then 0.24 parts of dodecyl dimethyl benzyl ammonium bromide, 0.35 parts of polyethylene glycol 2000 and 2.2 parts of terephthalic acid are added, the temperature is increased to 120°C and kept for 26 hours, the product is filtered, washed with DMF for 2 times, and dried to obtain pre-reaction particles; S2: 2.3 parts of the pre-reaction particles, 0.68 parts of 1,4-diaminobenzene, 0.31 parts of p-aminobenzoic acid and 0.14 parts of 2-methyl imidazole are mixed into 120 parts of DMF, stirred at 75°C and 240 rpm for 18 hours; S3: then the temperature is increased to 105°C, and kept for 16 hours of reaction, after the reaction is completed, the product is filtered, washed with DMF for 3 times, and dried at 85°C under vacuum for 8 hours, and the modified titanium dioxide is obtained after the completion.

[0063] The average particle size of the titanium dioxide is 5.5 nm; and the average particle size of the modified titanium dioxide is 538 nm.

[0064] The preparation method of the reflective heat insulation color paste specifically comprises the following steps, in terms of mass parts: S1: 60 parts of deionized water are added into a high-speed mixer, then 2.4 parts of sodium polycarboxylate, 0.8 parts of cocamide propyl betaine, 0.16 parts of defoamer BYK-066N and 26.5 parts of reflective heat insulation pigment are sequentially added, stirred at 800 rpm for 15 minutes to ensure uniform dispersion, then 2.8 parts of hydroxyethyl cellulose and sodium hydroxide are added to adjust the pH to 7.5, then the stirring speed is increased to 1400 rpm to keep high-speed dispersion for 50 minutes to ensure that the reflective heat insulation pigment is fully dispersed, and a stable pre-dispersion liquid is formed; S2: the pre-dispersion liquid is transferred into a sand mill and sand-milled for 90 minutes, then transferred into a mixing kettle to add 0.5 parts of sodium polyacrylate, 1.1 parts of propylene glycol and 0.3 parts of thienimidazole, the stirring speed is adjusted to 700 rpm, and stirred for 25 minutes, then the mixed product is filtered through a 250-mesh screen to remove large-particle impurities, and sealed for storage.

[0065] The reflective heat insulation pigment is zinc yellow iron, which is purchased from P.Y.119 type product sold by Hunan Jufa Pigment Technology Co., Ltd.

[0066] The cellulose ether is a combination of hydroxyethyl cellulose and methyl hydroxyethyl cellulose, and the mass ratio of the two is 3.5:1.

[0067] The pH regulator is sodium hydroxide; and the dispersant is cocobetaine.

[0068] The wetting agent is polysiloxane BYK-348; and the defoamer is silicone defoamer BYK-066N.

[0069] The rheological aid is a combination of an acrylic and hydrogenated castor oil in a mass ratio of 2.5:5.8. The acrylic is purchased from Dow Chemical Company under the product name Acrysol TT-935; the polyurethane is purchased from Dow Chemical Company under the product name Acrysol 8W.

[0070] The anti-freezing agent is a combination of polyethylene glycol and non-ionic surfactant in a mass ratio of 3.6:1.4.

[0071] The film-forming aid is a combination of dodecanol ester and hexadecanol ester in a mass ratio of 7:2.

[0072] The mildewproof and antibacterial agent is a combination of benzimidazolone and methylisothiazolinone in a mass ratio of 1.0:1.0.

[0073] The second aspect of the embodiment provides a preparation method of the waterproof and decorative integrated reflective thermal insulation water-based polyurethane exterior wall coating, and specifically comprises the following steps: S1: adding deionized water in a mixing container, sequentially adding fillers, modified particles, and reflective thermal insulation color paste, continuously stirring for 35 min to ensure uniform dispersion, adding cellulose ether, pH adjuster, dispersant, wetting agent, and defoaming agent, continuing to stir for 15 min, increasing the stirring speed to 1200-1500 rpm, and maintaining high-speed dispersion for 45 min to ensure sufficient dispersion, to form a stable pre-dispersion liquid; S2: then slowly adding the water-based polyurethane emulsion, stirring at a speed of 450 rpm during the adding process to ensure uniform mixing; S3: adding the rheological aid, the anti-freezing agent, the film-forming aid, and the mildewproof and antibacterial agent, adjusting the stirring speed to 680 rpm, and stirring for 25 min, then filtering the mixed product through a 200-mesh screen to remove large-particle impurities, and then packaging the filtered coating into clean and dry containers for sealing and storage.

[0074] Example 2

[0075] The specific implementation of the embodiment is basically the same as that of Example 1, except that the waterproof and decorative integrated reflective thermal insulation water-based polyurethane exterior wall coating comprises, by mass percentage, 40% of the water-based polyurethane emulsion, 27% of the fillers, 18% of the modified particles, 4.5% of the reflective thermal insulation color paste, 0.4% of the cellulose ether, 0.22% of the pH adjuster, 0.41% of the dispersant, 0.16% of the wetting agent, 0.35% of the defoaming agent, 0.44% of the rheological aid, 0.8% of the anti-freezing agent, 2.3% of the film-forming aid, 0.32% of the mildewproof and antibacterial agent, and the balance of deionized water.

[0076] The cellulose ether is a combination of methylhydroxyethyl cellulose and hydroxyethyl cellulose in a mass ratio of 3:1.2.

[0077] The rheological assistant is a combination of acrylic and polyurethane, with a mass ratio of 2:5.5.

[0078] The film forming assistant is a combination of dodecanol ester and hexadecanol ester, with a mass ratio of 8:1.5.

[0079] Example 3

[0080] The specific implementation of this example is basically the same as that of Example 1, with the difference being that the waterproof and decorative integrated reflective thermal waterborne polyurethane exterior wall coating has the following raw materials in mass percentage: waterborne polyurethane emulsion 40%, filler 32%, modified particles 13%, reflective thermal color paste 4.5%, cellulose ether 0.4%, pH adjuster 0.22%, dispersant 0.41%, wetting agent 0.16%, defoaming agent 0.35%, rheological assistant 0.44%, anti-freezing agent 0.8%, film forming assistant 2.3%, mildew and bacteria resistant agent 0.32%, and deionized water to make up the balance.

[0081] The cellulose ether is a combination of methylhydroxyethyl cellulose and hydroxyethyl cellulose, with a mass ratio of 4:1.

[0082] The rheological assistant is a combination of acrylic and polyurethane, with a mass ratio of 2.5:6.

[0083] The film forming assistant is a combination of dodecanol ester and hexadecanol ester, with a mass ratio of 6:2.5.

[0084] Comparative Example 1

[0085] The specific implementation of this example is basically the same as that of Example 1, with the difference being that the waterproof and decorative integrated reflective thermal waterborne polyurethane exterior wall coating has the following raw materials in mass percentage: waterborne polyurethane emulsion 37.5%, filler 30%, modified particles 15%, commercially available ordinary color paste 4.4%, cellulose ether 0.4%, pH adjuster 0.22%, dispersant 0.41%, wetting agent 0.16%, defoaming agent 0.35%, rheological assistant 0.44%, anti-freezing agent 0.8%, film forming assistant 2.3%, mildew and bacteria resistant agent 0.32%, and deionized water to make up the balance.

[0086] Comparative Example 2

[0087] The specific embodiment of the comparative example is basically the same as that of Example 1, except that the waterproof and decorative integrated reflective thermal insulation waterborne polyurethane exterior wall coating has the following raw materials in mass percentage: waterborne polyurethane emulsion 35%, filler 30%, modified particles 18.5%, commercially available ordinary color paste 4.4%, cellulose ether 0.4%, pH adjuster 0.22%, dispersant 0.41%, wetting agent 0.16%, defoaming agent 0.35%, rheological aid 0.44%, anti-freezing agent 0.8%, film-forming aid 2.3%, mildew and bacteria resistant agent 0.32%, and deionized water to make up the balance.

[0088] Comparative Example 3

[0089] The specific embodiment of the comparative example is basically the same as that of Example 1, except that the waterproof and decorative integrated reflective thermal insulation waterborne polyurethane exterior wall coating has the following raw materials in mass percentage: waterborne polyurethane emulsion 32.5%, filler 35%, modified particles 18.5%, commercially available ordinary color paste 4.4%, cellulose ether 0.4%, pH adjuster 0.22%, dispersant 0.41%, wetting agent 0.16%, defoaming agent 0.35%, rheological aid 0.44%, anti-freezing agent 0.8%, film-forming aid 2.3%, mildew and bacteria resistant agent 0.32%, and deionized water to make up the balance.

[0090] Comparative Example 4

[0091] The specific embodiment of the comparative example is basically the same as that of Example 1, except that the preparation method of the reflective thermal insulation color paste specifically includes the following steps in mass parts: S1: 60 parts of deionized water are added in a high-speed mixer, followed by sequentially adding 1.5 parts of sodium polycarboxylate, 0.2 parts of cocamidopropyl betaine, 0.16 parts of defoaming agent BYK-066N, and 38.8 parts of reflective thermal insulation pigment, stirring at 800 rpm for 15 min to ensure uniform dispersion, then adding 1.6 parts of hydroxyethyl cellulose, and adding sodium hydroxide to adjust the pH to 7.5, then increasing the speed to 1400 rpm for high-speed dispersion for 50 min to ensure that the reflective thermal insulation pigment is fully dispersed, forming a stable pre-dispersion liquid; S2: the pre-dispersion liquid is transferred to a sand mill and sand-milled for 90 min, then transferred to a mixing kettle and adding 0.2 parts of sodium polyacrylate, 1.1 parts of propylene glycol, and 0.3 parts of thiazolimidazole, adjusting the stirring speed to 700 rpm, stirring for 25 min, then filtering the mixed product through a 250-mesh screen to remove large particle impurities, and sealing for storage.

[0092] Comparative Example 5

[0093] The specific implementation of the comparative example is basically the same as that of example 1, except that the preparation method of the modified titanium dioxide specifically comprises the following steps, in terms of mass parts: S1: 3.6 parts of titanium dioxide and 1.2 parts of zinc chloride are mixed and added into 120 parts of DMF solution, 1.5 parts of succinic anhydride are added, and the temperature is raised to 75°C for 3h, after the reaction is completed, diethylamine is added to adjust the pH to 7.5, then 0.11 parts of dodecyl dimethyl benzyl ammonium bromide, 0.15 parts of polyethylene glycol 2000 and 1 part of terephthalic acid are added, the temperature is raised to 120°C for 26h, the product is filtered, washed with DMF for 2 times, and dried to obtain pre-reaction particles; S2: 2.3 parts of pre-reaction particles, 0.68 parts of 1,4-diaminobenzene, 0.31 parts of p-aminobenzoic acid and 0.14 parts of 2-methyl imidazole are mixed into 120 parts of DMF, stirred at 75°C and 240rpm for 18h; S3: then the temperature is raised to 105°C, and the reaction is kept for 16h, after the reaction is completed, the product is filtered, washed with DMF for 3 times, and vacuum dried at 85°C for 8h, and then the modified titanium dioxide is obtained.

[0094] The average particle size of the modified titanium dioxide is 411nm.

[0095] Comparative example 6

[0096] The specific implementation of the comparative example is basically the same as that of example 1, except that the preparation method of the modified titanium dioxide specifically comprises the following steps, in terms of mass parts: S1: 3.6 parts of titanium dioxide and 1.2 parts of zinc chloride are mixed and added into 120 parts of DMF solution, 1.5 parts of succinic anhydride are added, and the temperature is raised to 75°C for 3h, after the reaction is completed, diethylamine is added to adjust the pH to 7.5, then 0.11 parts of dodecyl dimethyl benzyl ammonium bromide, 0.15 parts of polyethylene glycol 2000 and 1 part of terephthalic acid are added, the temperature is raised to 120°C for 26h, the product is filtered, washed with DMF for 2 times, and dried to obtain pre-reaction particles; S2: 2.3 parts of pre-reaction particles, 0.68 parts of 1,4-diaminobenzene, 0.31 parts of p-aminobenzoic acid and 0.14 parts of 2-methyl imidazole are mixed into 120 parts of DMF, stirred at 75°C and 240rpm for 18h; S3: then the temperature is raised to 105°C, and the reaction is kept for 16h, after the reaction is completed, the product is filtered, washed with DMF for 3 times, and vacuum dried at 85°C for 8h, and then the modified titanium dioxide is obtained.

[0097] The average particle size of the modified titanium dioxide is 644nm.

[0098] Comparative example 7

[0099] The specific implementation of the comparative example is basically the same as that of example 1, except that the preparation method of the modified titanium dioxide specifically comprises the following steps, in terms of mass parts: S1: 3.6 parts of titanium dioxide and 1.2 parts of zinc chloride are mixed and added into 120 parts of DMF solution, 1.5 parts of succinic anhydride are added, and the temperature is raised to 75°C for 3h, after the reaction is completed, diethylamine is added to adjust the pH to 7.5, then 0.11 parts of dodecyl dimethyl benzyl ammonium bromide, 0.15 parts of polyethylene glycol 2000 and 1 part of terephthalic acid are added, the temperature is raised to 120°C for 26h, the product is filtered, washed with DMF for 2 times, and dried to obtain pre-reaction particles; S2: 2.3 parts of pre-reaction particles, 0.68 parts of 1,4-diaminobenzene, 0.31 parts of p-aminobenzoic acid and 0.14 parts of 2-methyl imidazole are mixed into 120 parts of DMF, stirred at 75°C and 240rpm for 18h; S3: then the temperature is raised to 105°C, and the reaction is kept for 16h, after the reaction is completed, the product is filtered, washed with DMF for 3 times, and vacuum dried at 85°C for 8h, and then the modified titanium dioxide is obtained.

[0100] Performance evaluation

[0101] Aging resistance test: The products prepared in the examples and comparative examples were subjected to 1000h aging resistance test according to the standard GB / T 9755-2014, and the color change value (ΔE) was taken. The test value was the average value of 10 tests, which was recorded in Table 1.

[0102] Near-infrared reflection performance test: The products prepared in the examples and comparative examples were subjected to near-infrared reflection performance test according to the standard JG / T 235-2014, and the test value was the average value of 10 tests, which was recorded in Table 1.

[0103] Mechanical mechanical test: The products prepared in the examples and comparative examples were subjected to tensile strength and elongation at break test according to the standard JC / T 864-2023, and the test value was the average value of 10 tests, which was recorded in Table 1.

[0104] Water resistance test: The products prepared in the examples and comparative examples were subjected to water resistance test according to the standard JC / T 864-2023, and the test pressure was 0.4MPa. The pressure needed to be maintained for 4h without water leakage. If there was water leakage, it was recorded as unqualified, otherwise it was qualified. 100 groups of samples were tested in each group, and the qualified rate results were recorded in Table 1.

[0105]

[0106] From the data results of the examples and comparative examples of the present application and Table 1, it can be seen that the examples 1-3 of the present application have obvious advantages in mechanical mechanical properties, waterproof performance, aging resistance and reflection heat insulation performance, etc. compared with the comparative examples 1-7. This is mainly because the modified titanium dioxide used in the examples of the present application can better interact with the waterborne polyurethane system. On the premise of absorbing a small amount of light energy, it can form a good heterojunction structure. The existence of the structure can greatly enhance the aggregation degree and stability of the oxidized molecules on the particle surface, thereby maintaining the good impedance of active molecules and organic molecules during long-term use, thereby obtaining excellent corrosion resistance and aging resistance, etc. In addition, it can also greatly reduce the micropore porosity of the modified particles in the system, reduce the large gaps formed by the series connection of the pores, and thereby greatly enhance the barrier effect of the exterior wall coating on water and active molecules, thereby maintaining excellent corrosion resistance, etc.

Claims

1. A waterproof and decorative integrated reflective and heat-insulating polyurethane exterior wall coating, characterized in that: By weight percentage, the raw materials are: 30-40% waterborne polyurethane emulsion, 20-30% filler, 8-12% modified particles, 3-6% reflective heat-insulating color paste, 0.3-0.5% cellulose ether, 0.2-0.3% pH adjuster, 0.3-0.5% dispersant, 0.1-0.2% wetting agent, 0.3-0.5% defoamer, 0.3-0.5% rheology modifier, 0.5-1% antifreeze agent, 2-2.5% film-forming aid, 0.3-0.6% mildew and antibacterial agent, and deionized water to make up the balance. The solid content of the waterborne polyurethane emulsion is 30-50%; the viscosity of the waterborne polyurethane emulsion is 300-2000 mPa·s, under the condition of 25℃. The filler is at least one selected from barium sulfate, calcium carbonate, talc, kaolin, and diatomaceous earth; the average particle size of the filler is 0.1~1μm; The modified particles are modified titanium dioxide; The specific preparation method of the modified titanium dioxide is as follows. Includes the following steps: S1: Titanium dioxide and zinc chloride are mixed and added to DMF solution, succinic anhydride is added, and the temperature is raised to 70-75℃ and kept at this temperature for 3-3.5h. After the reaction is complete, diethylamine is added to adjust the pH to 7.5-8, followed by the addition of dodecyl dimethyl benzyl ammonium bromide, polyethylene glycol 2000 and terephthalic acid. The temperature is raised to 110-120℃ and kept at this temperature for 24-30h. The product is filtered, washed 2-3 times with DMF, and dried to obtain pre-reacted particles. S2: The pre-reacted particles, 1,4-diaminobenzene, p-aminobenzoic acid and 2-methylimidazole are mixed and added to DMF. The mixture is stirred at 70-80℃ and 200-300rpm for 16-20h. S3: The temperature is then raised to 100-110℃ and the reaction is kept at this temperature for 14-16h. After the reaction is complete, the product is filtered, washed 2-3 times with DMF, and dried under vacuum at 80-90℃ for 6-8h. The product is then obtained. The pH adjuster is at least one selected from ammonia, triethanolamine, sodium hydroxide, 2-amino-2-methyl-1-propanol, and triethylamine; The mass ratio of titanium dioxide, zinc chloride, and succinic anhydride is (2.3~2.6):(1.8~2.1):(1~1.2). The mass ratio of titanium dioxide, dodecyl dimethyl benzyl ammonium bromide, polyethylene glycol 2000 and terephthalic acid is (2.3~2.6):(0.2~0.25):(0.3~0.4):(2~2.5). The pre-reacted particles, 1,4-diaminobenzene, p-aminobenzoic acid and 2-methylimidazole, have a mass ratio of (2.1~2.4):(0.6~0.8):(0.2~0.4):(0.1~0.2). The titanium dioxide has an average particle size of 5-10 nm; the modified titanium dioxide has an average particle size of 500-600 nm. The waterborne polyurethane emulsion has a filler to modified particle mass ratio of (32~38):(22~26):(10~12); the cellulose ether is a composition of methyl hydroxyethyl cellulose and hydroxyethyl cellulose; the mass ratio of methyl hydroxyethyl cellulose to hydroxyethyl cellulose is (3~4):(1~1.2). The rheology modifier is a composition of acrylic rheology modifier and polyurethane rheology modifier; the mass ratio of the acrylic rheology modifier to the polyurethane rheology modifier is (2~2.5):(5.5~6); The film-forming aid is a composition of dodecyl alcohol ester and hexadecyl alcohol ester; the mass ratio of the dodecyl alcohol ester and hexadecyl alcohol ester is (6~8):(1.5~2.5). The dispersant is coconut oil-based betaine; The specific preparation method of the reflective heat-insulating color paste Includes the following steps: S1: Add deionized water to a high-speed mixer, then add sodium polycarboxylate, cocamidopropyl betaine, defoamer BYK-066N and reflective heat-insulating pigment in sequence. Stir at 600~800 rpm for 15~20 min to ensure uniform dispersion. Then add hydroxyethyl cellulose and sodium hydroxide solution to adjust the pH to 8~8.

5. Then increase the speed to 1200~1500 rpm and maintain high-speed dispersion for 40~60 min to ensure that the reflective heat-insulating pigment is fully dispersed and a stable pre-dispersion is formed. S2: Transfer the pre-dispersed liquid to a sand mill and mill for 80-100 minutes. Then transfer it to a mixing tank and add polyurethane rheology modifier, propylene glycol and thiabendazole. Adjust the stirring speed to 650-750 rpm and stir for 20-30 minutes. Then filter the mixture through a 200-300 mesh sieve to remove large particulate impurities. Seal and store to obtain the final product.

2. A method for preparing a waterproof and decorative integrated reflective thermal insulation polyurethane exterior wall coating according to claim 1, characterized in that: S1: Add deionized water to a mixing container, then add filler, modified particles, and reflective heat-insulating pigment in sequence. Stir continuously for 30-40 minutes to ensure uniform dispersion. Add cellulose ether, pH adjuster, dispersant, wetting agent, and defoamer, and continue stirring for 15-20 minutes. Increase the speed to 1200-1500 rpm and maintain high-speed dispersion for 30-60 minutes to ensure full dispersion and form a stable pre-dispersion. S2: Slowly add waterborne polyurethane emulsion while stirring at 400-500 rpm to ensure uniform mixing. S3: Add rheology modifier, antifreeze, film-forming aid, and antifungal and antibacterial agent. Adjust the stirring speed to 650-750 rpm and stir for 20-30 minutes. Then filter the mixture through a 100-200 mesh sieve to remove large particulate impurities. Dispense the filtered coating into clean, dry containers, seal and store.

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