Preparation method of environment-friendly waterproof thermal insulation coating

Abstract

The application discloses a preparation method of an environment-friendly waterproof thermal insulation coating, and comprises the following steps: step S1, adding fillers and pigments into water, stirring for 1-2 hours under the condition of a rotating speed of 800-1000 r / min, and obtaining a mixed solution 1; step S2, adding polyacrylate emulsion, polyurethane and modified hollow glass microbeads into the mixed solution 1, stirring for 2-3 hours under the condition of a rotating speed of 600-800 r / min, and obtaining a mixed solution 2; and step S3, adding a dispersing agent, a stabilizing agent, a defoaming agent, a film-forming aid and a preservative into the mixed solution 2, stirring for 30-60 minutes under the condition of a rotating speed of 500-600 r / min, and obtaining the environment-friendly waterproof thermal insulation coating. The fillers nano-SiO2 and the hollow glass microbeads are modified, the prepared coating does not contain harmful gases such as benzene and formaldehyde, is economic, safe and environment-friendly, has good thermal insulation effect, good waterproof performance, long service life and good application prospect.

Description

Technical Field

[0001] This invention belongs to the field of coating technology, specifically relating to a method for preparing an environmentally friendly waterproof and heat-insulating coating. Background Technology

[0002] Waterproof coatings are an important component of functional building materials. During construction, waterproof coatings form a waterproof layer on the building surface to achieve waterproofing and leak-proofing. Therefore, the performance and selection of waterproof coatings directly affect the building's usability and lifespan. Currently, the main waterproof coatings on the market are polyurethane waterproof coatings and acrylic waterproof coatings. Polyurethane waterproof coatings have excellent mechanical properties and good waterproofing performance, but poor weather resistance. They are prone to blistering in high-temperature and high-humidity environments, require a high degree of dryness of the substrate, and may contain free isocyanates that are harmful to human health. Acrylic waterproof coatings have better weather resistance and environmental friendliness, but the water resistance of the coating film is poor, and application is difficult under low-temperature and high-humidity conditions.

[0003] With human development and the continuous exploitation and utilization of global resources and energy, energy conservation and emission reduction have become a fundamental national policy, and energy-saving materials have attracted widespread attention. Thermal insulation coatings are a new type of energy-saving material developed in recent years. They effectively reflect the energy of sunlight, reducing the absorption of solar radiation energy by the surface of objects, thereby achieving the effects of heat insulation, reducing the surface temperature of objects, and preventing heat conduction. Based on different thermal insulation mechanisms and methods, thermal insulation coatings can be divided into barrier type, reflective type, and radiative type. Chinese patent CN111154357A discloses an exterior wall thermal insulation coating and its preparation method. The coating comprises the following components in parts by weight: 40-50 parts base material and 30-40 parts filler. The composition includes: 5-10 parts of pigment, 30-40 parts of water, 1-3 parts of dispersant, 0.1-0.3 parts of stabilizer, 0.3-0.8 parts of pH adjuster, and 0.1-0.3 parts of defoamer; the base material is an epoxy resin modified base material system, which is a copolymer emulsion prepared from 35-40 parts of acrylic acid, 20-30 parts of butyl acrylate, 5-15 parts of styrene, and 3-8 parts of acrylamide as raw materials; The epoxy resin is a bisphenol A epoxy resin modified with hydroxyl-terminated polydimethylsiloxane and glycidyl methacrylate. This invention patent uses silicone-modified epoxy resin to modify acrylic emulsion base material, which makes the coating system have better high and low temperature resistance after film formation, reduced shrinkage rate, no cracking and peeling under long-term hot environment, and longer service life. Chinese patent CN112126284A discloses an exterior wall waterproof and thermal insulation coating and its preparation method. The raw materials used in the coating include the following components by weight: 40-60 parts styrene-acrylic emulsion, 15-20 parts reinforcing fiber, 5-10 parts TiO2-modified hollow glass microspheres, 10-12 parts silk fibroin solution, 10-14 parts nanofiller, 3-5 parts epoxidized soybean oil, 2-3 parts dodecyl methacrylate, 3-4 parts polymethyltriethoxysilane, 1-3 parts dispersant, 0.2-0.5 parts preservative and bactericide, 1-2 parts film-forming aid, and 15-25 parts water. This invention's exterior wall waterproof and thermal insulation coating has high thermal insulation performance and mechanical properties, thereby extending the service life of the exterior wall. However, the fillers in the aforementioned prior art have poor compatibility in the coating system, leading to reduced adhesion and decreased waterproof performance. Therefore, with the continuous improvement of living standards and the increasing demands for environmental protection, researching a coating preparation method that is both waterproof and heat-insulating and environmentally friendly is a technical problem that the coating industry urgently needs to solve. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a method for preparing an environmentally friendly waterproof and heat-insulating coating. This application modifies the filler nano-SiO2 and hollow glass microspheres to prepare a coating that is free of harmful gases such as benzene and formaldehyde. It is economical, safe, and environmentally friendly, with good heat insulation, excellent waterproof performance, and a long service life, showing promising application prospects.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A method for preparing an environmentally friendly waterproof and heat-insulating coating, wherein the environmentally friendly waterproof and heat-insulating coating comprises the following raw materials in parts by weight: 90-120 parts of polyacrylate emulsion, 50-70 parts of polyurethane, 50-60 parts of filler, 10-15 parts of pigment, 2-4 parts of dispersant, 3-5 parts of defoamer, 5-10 parts of film-forming aid, 1-3 parts of preservative, 15-20 parts of modified hollow glass microspheres, and 30-50 parts of water; The preparation method of the environmentally friendly waterproof and heat-insulating coating includes the following steps: Step S1: Add filler and pigment to water and stir for 1-2 hours at a speed of 800-1000 r / min to obtain mixture 1; Step S2: Add polyacrylate emulsion, polyurethane and modified hollow glass microspheres to the mixture 1 obtained in step S1, and stir for 2-3 hours at a speed of 600-800 r / min to obtain mixture 2. Step S3: Add dispersant, stabilizer, defoamer, film-forming aid and preservative to the mixture 2 obtained in step S2, and stir for 30-60 minutes at a speed of 500-600 r / min to obtain an environmentally friendly waterproof and heat-insulating coating.

[0006] Further, the filler is modified nano-SiO2, which is obtained by the following method: at room temperature, nano-SiO2, dispersant SK-5040, silane coupling agent KH560 and water are dispersed at a speed of 1000-1200 r / min for 30-40 min, then the pH value is adjusted to 8.5-9.5 with a pH adjuster, and then ultrasonically dispersed for 40-60 min to obtain modified nano-SiO2; wherein, the mass ratio of nano-SiO2 to dispersant SK-5040, silane coupling agent KH560 and water is 1:(0.1-0.2):(0.25-0.35):(55-60).

[0007] Furthermore, the pigment is a composition of titanium dioxide nanoparticles and iron oxide yellow titanium dioxide, with a mass ratio of (1-3):1.

[0008] Furthermore, the dispersant is at least one of ammonium polyacrylate or sodium polyacrylate; the defoamer is an organosilicon defoamer with a solid content >99.9%.

[0009] Furthermore, the film-forming aid is at least one of dodecyl alcohol ester or polyether polyol dodecyl ester.

[0010] Furthermore, the preservative is at least one of isothiazolinone derivatives or benzomirtazole ester preservatives.

[0011] Furthermore, the modified hollow glass microspheres are obtained by the following preparation method: (1) Add hollow glass microspheres to sodium hydroxide solution and heat at 55°C. Stir at 60°C for 4-5 hours, then wash alternately with deionized water and anhydrous ethanol, filter under reduced pressure to remove excess water, and dry to obtain pretreated hollow glass microspheres. (2) Add the silane coupling agent 3-glycidoxypropyltrimethoxysilane to anhydrous ethanol solution, adjust the pH to 5.0-7.0, and hydrolyze for 2-3 hours to obtain a coupling agent hydrolysis solution. Then add the pretreated hollow glass microspheres obtained in step (1) to the coupling agent hydrolysis solution and heat at 50°C. Stir at 60°C for 5-6 hours, then wash alternately with deionized water and anhydrous ethanol, and dry at 75-85°C for 10-12 hours to obtain coupling agent modified hollow glass microspheres. (3) Add the coupling agent modified hollow glass microspheres and polyethyleneimine obtained in step (2) to deionized water, stir evenly in a nitrogen atmosphere, heat to 85-90°C for 6-10 hours, cool, wash and dry to obtain modified hollow glass microspheres.

[0012] Furthermore, in step (1), the mass ratio of hollow glass microspheres to sodium hydroxide is 1:(12.5-15); the mass percentage of sodium hydroxide solution is 30-50%.

[0013] Further, in step (2), the ratio of the amount of silane coupling agent 3-glycidoxypropyltrimethoxysilane, anhydrous ethanol solution and pretreated hollow glass microspheres is (0.5-0.75):(8.5-12):1; the volume fraction of the anhydrous ethanol solution is 99.5%.

[0014] Furthermore, in step (3), the mass ratio of deionized water, coupling agent-modified hollow glass microspheres, and polyethyleneimine is (45-65):(0.3-0.6):1.

[0015] Compared with the prior art, the positive and beneficial effects of this invention are as follows: (1) Nano SiO2 has advantages such as high heat resistance and high strength. When it is used as a nano filler in coatings, it can make the coating absorb ultraviolet light and reflect infrared light, thus achieving the purpose of resisting ultraviolet aging and preventing heat aging, and significantly improving the heat insulation performance of the coating. At the same time, by modifying nano SiO2, this invention improves the dispersibility of nano SiO2 in the coating, improves the compatibility between the filler and the polyacrylate emulsion, thereby improving the density of the coating, and thus making the coating have strong waterproof, stable and aging resistance.

[0016] (2) This invention modifies hollow glass microspheres by first grafting a coupling agent, 3-glycidoxypropyltrimethoxysilane, onto their surface, followed by grafting polyethyleneimine. This results in the presence of vinyl and silane groups on the surface of the hollow glass microspheres, improving the compatibility between the hollow glass microspheres and raw materials such as polyacrylate emulsions, polyurethanes, filler-modified nano-SiO2, and pigments. This, in turn, improves the stability and heat insulation effect of the coating. Furthermore, the polyethyleneimine grafted onto the surface of the hollow glass microspheres has strong adhesion and adsorption properties, allowing the modified hollow glass microspheres to be firmly adsorbed onto the surface of the nanofiller. This process ensures stable dispersion of the hollow glass microspheres in the coating, while also allowing inorganic particles such as hollow glass microspheres and filler-modified nano-SiO2 to adhere tightly to the building surface. This significantly reduces subsequent peeling and cracking of the coating, thereby improving its waterproofness and extending its service life. Furthermore, the modified hollow glass microspheres can work synergistically with polyacrylate emulsions and polyurethane to enhance the adhesion between the coating and the substrate, while also improving the coating's water resistance. The modified hollow glass microspheres can also work in concert with filler-modified nano-SiO2 to improve the coating's waterproofness, heat insulation, and aging resistance.

[0017] (3) The method for preparing the environmentally friendly waterproof and heat-insulating coating of the present invention is simple, the coating prepared does not contain harmful gases such as benzene and formaldehyde, is economical, safe and environmentally friendly, has good heat insulation effect, excellent waterproof performance, long service life and good application prospects. Detailed Implementation

[0018] The technical solution of the present invention will be further described in detail below through embodiments. These embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.

[0019] Unless otherwise specified, the experimental methods described in the examples and comparative examples are conventional methods; unless otherwise specified, the reagents and materials described are commercially available.

[0020] Example 1 A method for preparing an environmentally friendly waterproof and heat-insulating coating, comprising the following raw materials in parts by weight: 90 parts polyacrylate emulsion, 70 parts polyurethane, 50 parts filler, 10 parts pigment, 2 parts dispersant, 3 parts defoamer, 5 parts film-forming aid, 1 part preservative, 15 parts modified hollow glass microspheres, and 30 parts water; wherein the pigment is a composition of titanium dioxide nanoparticles and iron oxide yellow titanium dioxide in a mass ratio of 1:1; the dispersant is ammonium polyacrylate; the defoamer is an organosilicon defoamer with a solid content >99.9%; the film-forming aid is dodecyl alcohol ester; and the preservative is isothiazolinone derivative. The preparation method of the environmentally friendly waterproof and heat-insulating coating includes the following steps: Step S1: Add filler and pigment to water and stir for 2 hours at a speed of 800 r / min to obtain mixture 1; Step S2: Add polyacrylate emulsion, polyurethane and modified hollow glass microspheres to the mixture 1 obtained in step S1, and stir for 3 hours at a speed of 600 r / min to obtain mixture 2. Step S3: Add dispersant, stabilizer, defoamer, film-forming aid and preservative to the mixture 2 obtained in step S2, and stir for 60 minutes at a speed of 500 r / min to obtain an environmentally friendly waterproof and heat-insulating coating.

[0021] The filler is modified nano-SiO2, which is obtained by the following method: at room temperature, nano-SiO2, dispersant SK-5040, silane coupling agent KH560 and water are dispersed at a speed of 1000 r / min for 40 min, then the pH value is adjusted to 8.5-9.5 with a pH adjuster, and then ultrasonically dispersed for 40 min to obtain modified nano-SiO2; wherein, the mass ratio of nano-SiO2 to dispersant SK-5040, silane coupling agent KH560 and water is 1:0.1:0.25:55.

[0022] Modified hollow glass microspheres were obtained by the following preparation method: (1) Hollow glass microspheres were added to sodium hydroxide solution and stirred at 55°C for 5 hours. Then, they were washed alternately with deionized water and anhydrous ethanol, filtered under reduced pressure to remove excess water, and dried to obtain pretreated hollow glass microspheres. The mass ratio of hollow glass microspheres to sodium hydroxide was 1:12.5, and the mass percentage of sodium hydroxide solution was 30-50%. (2) The silane coupling agent 3-glycidoxypropyltrimethoxysilane was added to anhydrous ethanol solution, the pH was adjusted to 5.0-7.0, and hydrolyzed for 2-3 hours to obtain a coupling agent hydrolysis solution. The pretreated hollow glass microspheres obtained in step (1) were then added to the coupling agent hydrolysis solution and stirred at 50°C for 6 hours. The microspheres were then washed alternately with deionized water and anhydrous ethanol and dried at 75°C for 12 hours to obtain coupling agent modified hollow glass microspheres. The ratio of the amount of silane coupling agent 3-glycidoxypropyltrimethoxysilane, anhydrous ethanol solution and pretreated hollow glass microspheres was 0.5:8.5:1. The volume fraction of the anhydrous ethanol solution was 99.5%.

[0023] (3) Add the coupling agent-modified hollow glass microspheres and polyethyleneimine obtained in step (2) to deionized water, stir evenly in a nitrogen atmosphere, heat to 850°C and react for 10 h, cool, wash and dry to obtain modified hollow glass microspheres. The mass ratio of deionized water, coupling agent-modified hollow glass microspheres and polyethyleneimine is 45:0.3:1.

[0024] Example 2 A method for preparing an environmentally friendly waterproof and heat-insulating coating, comprising the following raw materials in parts by weight: 105 parts polyacrylate emulsion, 60 parts polyurethane, 55 parts filler, 12 parts pigment, 3 parts dispersant, 4 parts defoamer, 8 parts film-forming aid, 2 parts preservative, 18 parts modified hollow glass microspheres, and 40 parts water; wherein the pigment is a composition of titanium dioxide nanoparticles and iron oxide yellow titanium dioxide in a mass ratio of 2:1; the dispersant is sodium polyacrylate; the defoamer is an organosilicon defoamer with a solid content >99.9%; the film-forming aid is polyether polyol dodecyl ester; and the preservative is a benzo[i]azole ester preservative. The preparation method of the environmentally friendly waterproof and heat-insulating coating includes the following steps: Step S1: Add filler and pigment to water and stir for 1.5 hours at a speed of 900 r / min to obtain mixture 1; Step S2: Add polyacrylate emulsion, polyurethane and modified hollow glass microspheres to the mixture 1 obtained in step S1, and stir at 700 r / min for 2.5 h to obtain mixture 2. Step S3: Add dispersant, stabilizer, defoamer, film-forming aid and preservative to the mixture 2 obtained in step S2, and stir for 45 minutes at a speed of 550 r / min to obtain an environmentally friendly waterproof and heat-insulating coating.

[0025] The filler is modified nano-SiO2, which is obtained by the following method: at room temperature, nano-SiO2, dispersant SK-5040, silane coupling agent KH560 and water are dispersed at a speed of 1100 r / min for 35 min, then the pH value is adjusted to 8.5-9.5 with a pH adjuster, and then ultrasonically dispersed for 50 min to obtain modified nano-SiO2; wherein, the mass ratio of nano-SiO2 to dispersant SK-5040, silane coupling agent KH560 and water is 1:0.15:0.3:58.

[0026] Modified hollow glass microspheres were obtained by the following preparation method: (1) Hollow glass microspheres were added to sodium hydroxide solution and stirred at 57°C for 4.5 h. Then, they were washed alternately with deionized water and anhydrous ethanol, filtered under reduced pressure to remove excess water, and dried to obtain pretreated hollow glass microspheres. The mass ratio of hollow glass microspheres to sodium hydroxide was 1:14, and the mass percentage of sodium hydroxide solution was 30-50%. (2) The silane coupling agent 3-glycidoxypropyltrimethoxysilane was added to anhydrous ethanol solution, the pH was adjusted to 5.0-7.0, and hydrolyzed for 2-3 h to obtain a coupling agent hydrolysis solution. The pretreated hollow glass microspheres obtained in step (1) were then added to the coupling agent hydrolysis solution and stirred at 55°C for 5.5 h. The microspheres were then washed alternately with deionized water and anhydrous ethanol and dried at 80°C for 11 h to obtain coupling agent modified hollow glass microspheres. The ratio of the amount of silane coupling agent 3-glycidoxypropyltrimethoxysilane, anhydrous ethanol solution and pretreated hollow glass microspheres was 0.6:10:1. The volume fraction of the anhydrous ethanol solution was 99.5%. (3) Add the coupling agent-modified hollow glass microspheres and polyethyleneimine obtained in step (2) to deionized water, stir evenly in a nitrogen atmosphere, heat to 88°C and react for 8 hours, cool, wash and dry to obtain modified hollow glass microspheres. The mass ratio of deionized water, coupling agent-modified hollow glass microspheres and polyethyleneimine is 55:0.5:1.

[0027] Example 3 A method for preparing an environmentally friendly waterproof and heat-insulating coating, comprising the following raw materials in parts by weight: 120 parts polyacrylate emulsion, 50 parts polyurethane, 60 parts filler, 15 parts pigment, 4 parts dispersant, 5 parts defoamer, 10 parts film-forming aid, 3 parts preservative, 20 parts modified hollow glass microspheres, and 50 parts water; wherein the pigment is a composition of titanium dioxide nanoparticles and iron oxide yellow titanium dioxide in a mass ratio of 3:1; the dispersant is ammonium polyacrylate; the defoamer is an organosilicon defoamer with a solid content >99.9%; the film-forming aid is polyether polyol dodecanoate; and the preservative is an isothiazolinone derivative. The preparation method of the environmentally friendly waterproof and heat-insulating coating includes the following steps: Step S1: Add filler and pigment to water and stir for 1 hour at a speed of 1000 r / min to obtain mixture 1; Step S2: Add polyacrylate emulsion, polyurethane and modified hollow glass microspheres to the mixture 1 obtained in step S1, and stir for 2 hours at a speed of 800 r / min to obtain mixture 2. Step S3: Add dispersant, stabilizer, defoamer, film-forming aid and preservative to the mixture 2 obtained in step S2, and stir for 30 minutes at a speed of 600 r / min to obtain an environmentally friendly waterproof and heat-insulating coating.

[0028] The filler is modified nano-SiO2, which is obtained by the following method: at room temperature, nano-SiO2, dispersant SK-5040, silane coupling agent KH560 and water are dispersed at a speed of 1200 r / min for 30 min, then the pH value is adjusted to 8.5-9.5 with a pH adjuster, and then ultrasonically dispersed for 60 min to obtain modified nano-SiO2; wherein, the mass ratio of nano-SiO2 to dispersant SK-5040, silane coupling agent KH560 and water is 1:0.2:0.35:60.

[0029] Modified hollow glass microspheres were obtained by the following preparation method: (1) Hollow glass microspheres were added to sodium hydroxide solution and stirred at 60°C for 4 hours. Then, they were washed alternately with deionized water and anhydrous ethanol, filtered under reduced pressure to remove excess water, and dried to obtain pretreated hollow glass microspheres. The mass ratio of hollow glass microspheres to sodium hydroxide was 1:15, and the mass percentage of sodium hydroxide solution was 30-50%. (2) The silane coupling agent 3-glycidoxypropyltrimethoxysilane was added to anhydrous ethanol solution, the pH was adjusted to 5.0-7.0, and hydrolyzed for 2-3 hours to obtain a coupling agent hydrolysis solution. The pretreated hollow glass microspheres obtained in step (1) were then added to the coupling agent hydrolysis solution and stirred at 60°C for 56 hours. The microspheres were then washed alternately with deionized water and anhydrous ethanol and dried at 85°C for 10 hours to obtain coupling agent modified hollow glass microspheres. The ratio of the amount of silane coupling agent 3-glycidoxypropyltrimethoxysilane, anhydrous ethanol solution and pretreated hollow glass microspheres was 0.7512:1. The volume fraction of the anhydrous ethanol solution was 99.5%. (3) Add the coupling agent-modified hollow glass microspheres and polyethyleneimine obtained in step (2) to deionized water, stir evenly in a nitrogen atmosphere, heat to 90°C and react for 6 hours, cool, wash and dry to obtain modified hollow glass microspheres. The mass ratio of deionized water, coupling agent-modified hollow glass microspheres and polyethyleneimine is 65:0.6:1.

[0030] Comparative Example 1 The preparation method of the environmentally friendly waterproof and heat-insulating coating in this comparative example is exactly the same as that in Example 2, except that the filler is unmodified nano-SiO2.

[0031] Comparative Example 2 The preparation method of the environmentally friendly waterproof and heat-insulating coating in this comparative example is exactly the same as that in Example 2, except that the modified hollow glass microspheres are not grafted with polyethyleneimine; the modified hollow glass microspheres in this comparative example are obtained by the following preparation method: (1) Hollow glass microspheres were added to sodium hydroxide solution and stirred at 57°C for 4.5 h. Then, they were washed alternately with deionized water and anhydrous ethanol, filtered under reduced pressure to remove excess water, and dried to obtain pretreated hollow glass microspheres. The mass ratio of hollow glass microspheres to sodium hydroxide was 1:14, and the mass percentage of sodium hydroxide solution was 30-50%. (2) The silane coupling agent 3-glycidoxypropyltrimethoxysilane was added to anhydrous ethanol solution, the pH was adjusted to 5.0-7.0, and hydrolyzed for 2-3 h to obtain a coupling agent hydrolysis solution. The pretreated hollow glass microspheres obtained in step (1) were then added to the coupling agent hydrolysis solution and stirred at 55°C for 5.5 h. The microspheres were then washed alternately with deionized water and anhydrous ethanol and dried at 80°C for 11 h to obtain modified hollow glass microspheres. The ratio of the amount of silane coupling agent 3-glycidoxypropyltrimethoxysilane, anhydrous ethanol solution and pretreated hollow glass microspheres was 0.6:10:1. The volume fraction of the anhydrous ethanol solution was 99.5%.

[0032] Comparative Example 3 The preparation method of the environmentally friendly waterproof and heat-insulating coating in this comparative example is exactly the same as that in Example 2, except that the hollow glass microspheres are not modified.

[0033] The coating samples prepared in Examples 1-3 and Comparative Examples 1-3 of the present invention were tested as follows, and the specific test results are shown in Table 1.

[0034] (1) Surface solar reflectance test: Tested according to JG / T235-2008 "Building Reflective Thermal Insulation Coatings"; (2) Thermal insulation performance test: The coating samples prepared in Examples 1-3 and Comparative Examples 1-3 were coated on a 10mm×10mm iron plate to make a sample, and the thermal insulation effect of the sample was tested under the same conditions. (3) Aging resistance test: The test shall be conducted in accordance with GB / T1865-1997, "Artificial Accelerated Test Method for Aging of Paint Film"; (4) Waterproof performance test: According to the test method in GB / T 1733-1993, the coatings prepared in Examples 1-3 and Comparative Examples 1-3 were applied to the tinplate. The water temperature was adjusted to 47-50℃, and 3% NaCl was added to the water. The tinplate coated with the coating was completely immersed in the salt water. The coating was observed every 48 hours, and the time of peeling, bubbling or cracking was recorded. (5) Adhesion test: The adhesion of the coating samples prepared in Examples 1-3 and Comparative Examples 1-3 was tested according to the method in GB / T1720-79; Table 1. Performance test results of the coatings prepared in Examples 1-3 and Comparative Examples 1-3 As can be seen from the data in Table 1, the coating prepared by this invention has good heat insulation, water resistance, aging resistance, and adhesion, and has good application prospects. A comparison between Comparative Example 1 and Example 2 shows that nano-SiO2 has advantages such as high heat resistance and high strength. Using it as a nanofiller in coatings allows the coating to absorb ultraviolet light and reflect infrared light, achieving the purpose of resisting ultraviolet aging and preventing heat aging, and significantly improving the heat insulation performance of the coating. Simultaneously, this invention improves the dispersibility of nano-SiO2 in the coating by modifying it, and improves the compatibility between the filler and the polyacrylate emulsion, thereby improving the density of the coating and thus giving it strong water resistance, stability, and aging resistance. As can be seen from the comparison between Comparative Examples 2-3 and Example 2, the present invention modifies hollow glass microspheres by first grafting the coupling agent 3-glycidoxypropyltrimethoxysilane onto their surface, and then grafting polyethyleneimine onto them. This results in the presence of vinyl and silane groups on the surface of the hollow glass microspheres, improving the compatibility between the hollow glass microspheres and raw materials such as polyacrylate emulsions, polyurethanes, filler-modified nano-SiO2, and pigments, thereby improving the stability and heat insulation effect of the coating. Moreover, the polyethyleneimine grafted onto the surface of the hollow glass microspheres has strong adhesion and adsorption properties, allowing the modified hollow glass microspheres to adhere firmly. The adsorption of these particles onto the surface of the nanofillers allows for stable dispersion in the coating. Simultaneously, it enables inorganic particles such as hollow glass microspheres and filler-modified nano-SiO2 to adhere tightly to the building surface, significantly reducing subsequent peeling and cracking of the coating, thereby improving its waterproofness and extending its service life. Furthermore, the modified hollow glass microspheres can interact with polyacrylate emulsions and polyurethane to enhance the adhesion between the coating and the substrate, while also improving the coating's water resistance. The modified hollow glass microspheres can also synergistically work with filler-modified nano-SiO2 to improve the coating's waterproofness, heat insulation, and aging resistance.

[0035] Finally, it should be noted that although embodiments of the present invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the present invention.

Claims

1. A method for preparing an environmentally friendly waterproof and heat-insulating coating, characterized in that, The environmentally friendly waterproof and heat-insulating coating comprises the following raw materials in parts by weight: 90-120 parts of polyacrylate emulsion, 50-70 parts of polyurethane, 50-60 parts of filler, 10-15 parts of pigment, 2-4 parts of dispersant, 3-5 parts of defoamer, 5-10 parts of film-forming aid, 1-3 parts of preservative, 15-20 parts of modified hollow glass microspheres, and 30-50 parts of water; The preparation method of the environmentally friendly waterproof and heat-insulating coating includes the following steps: Step S1: Add filler and pigment to water and stir for 1-2 hours at a speed of 800-1000 r / min to obtain mixture 1; Step S2: Add polyacrylate emulsion, polyurethane and modified hollow glass microspheres to the mixture 1 obtained in step S1, and stir for 2-3 hours at a speed of 600-800 r / min to obtain mixture 2. Step S3: Add dispersant, stabilizer, defoamer, film-forming aid and preservative to the mixture 2 obtained in step S2, and stir for 30-60 minutes at a speed of 500-600 r / min to obtain an environmentally friendly waterproof and heat-insulating coating.

2. The method for preparing an environmentally friendly waterproof and heat-insulating coating according to claim 1, characterized in that, The filler is modified nano-SiO2, which is obtained by the following method: at room temperature, nano-SiO2, dispersant SK-5040, silane coupling agent KH560 and water are dispersed at a speed of 1000-1200 r / min for 30-40 min, then the pH value is adjusted to 8.5-9.5 with a pH adjuster, and then ultrasonically dispersed for 40-60 min to obtain modified nano-SiO2; wherein, the mass ratio of nano-SiO2 to dispersant SK-5040, silane coupling agent KH560 and water is 1:(0.1-0.2):(0.25-0.35):(55-60).

3. The method for preparing an environmentally friendly waterproof and heat-insulating coating according to claim 1, characterized in that, The pigment is a composition of titanium dioxide nanoparticles and iron oxide yellow titanium dioxide, with a mass ratio of (1-3):

1.

4. The method for preparing an environmentally friendly waterproof and heat-insulating coating according to claim 1, characterized in that, The dispersant is at least one of ammonium polyacrylate or sodium polyacrylate; the defoamer is an organosilicon defoamer with a solid content >99.9%.

5. The method for preparing an environmentally friendly waterproof and heat-insulating coating according to claim 1, characterized in that, The film-forming aid is at least one of dodecyl alcohol ester or polyether polyol dodecyl ester.

6. The method for preparing an environmentally friendly waterproof and heat-insulating coating according to claim 1, characterized in that, The preservative is at least one of isothiazolinone derivatives or benzomirtazole ester preservatives.

7. The method for preparing an environmentally friendly waterproof and heat-insulating coating according to claim 1, characterized in that, The modified hollow glass microspheres were obtained by the following preparation method: (1) Add hollow glass microspheres to sodium hydroxide solution and stir at 55-60°C for 4-5 hours. Then wash with deionized water and anhydrous ethanol alternately, filter under reduced pressure to remove excess water, and dry to obtain pretreated hollow glass microspheres. (2) Add the silane coupling agent 3-glycidoxypropyltrimethoxysilane to anhydrous ethanol solution, adjust the pH to 5.0-7.0, and hydrolyze for 2-3 hours to obtain a coupling agent hydrolysis solution. Then add the pretreated hollow glass microspheres obtained in step (1) to the coupling agent hydrolysis solution and heat at 50°C. Stir at 60°C for 5-6 hours, then wash alternately with deionized water and anhydrous ethanol, and dry at 75-85°C for 10-12 hours to obtain coupling agent modified hollow glass microspheres. (3) Add the coupling agent modified hollow glass microspheres and polyethyleneimine obtained in step (2) to deionized water, stir evenly in a nitrogen atmosphere, heat to 85-90°C for 6-10 hours, cool, wash and dry to obtain modified hollow glass microspheres.

8. The method for preparing an environmentally friendly waterproof and heat-insulating coating according to claim 7, characterized in that, In step (1), the mass ratio of hollow glass microspheres to sodium hydroxide is 1:(12.5-15); the mass percentage of sodium hydroxide solution is 30-50%.

9. The method for preparing an environmentally friendly waterproof and heat-insulating coating according to claim 7, characterized in that, In step (2), the ratio of the amount of silane coupling agent 3-glycidoxypropyltrimethoxysilane, anhydrous ethanol solution and pretreated hollow glass microspheres is (0.5-0.75):(8.5-12):

1. The volume fraction of the anhydrous ethanol solution is 99.5%.

10. The method for preparing an environmentally friendly waterproof and heat-insulating coating according to claim 7, characterized in that, In step (3), the mass ratio of deionized water, coupling agent modified hollow glass microspheres and polyethyleneimine is (45-65):(0.3-0.6):1.

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