Preparation method of reflective thermal insulation coating containing Al2O3-TiO2 aerogel

Abstract

The invention discloses a reflective thermal insulation coating containing Al2O3-TiO2 aerogel and a preparation method of the reflective thermal insulation coating, and belongs to the technical field of coatings. The coating takes 100 parts of a compound adhesive as a matrix and comprises 20 to 40 parts of Al2O3-TiO2 aerogel, 50 to 75 parts of hollow glass beads and a functional aid, and the compound adhesive is prepared by compounding 60 to 80 parts of modified silicone acrylic emulsion, 10 to 20 parts of organic silicon emulsion and 10 to 15 parts of acidic silica sol. The aerogel is prepared from tetrabutyl titanate and nano Al2O3 through a sol-gel method, and a nano structure with the porosity larger than 90% is formed through CO2 supercritical drying (the pressure ranges from 10 MPa to 13 MPa, and the temperature ranges from 40 DEG C to 55 DEG C). During preparation, all the components are dispersed at a high speed for 30-60 min, the heat conductivity coefficient of the obtained coating is as low as 0.027 W / (m.K), the coating has double heat insulation mechanisms of reflection and blocking, the problems that traditional coating filler is not dispersed uniformly and the high-temperature performance is degraded are solved, and the coating is suitable for energy-saving protection of buildings and industrial equipment.

Description

Technical Field

[0001] The present invention belongs to the technical field of coatings, and particularly relates to a preparation method of an Al2O3-TiO2 aerogel reflective heat-insulating coating. Background Art

[0002] Since the 21st century, while vigorously developing the global economy, the damage to the environment has increased sharply, and environmental protection is extremely urgent. The country has vigorously promoted green and environmentally friendly as well as resource-saving industries. The energy consumption and pollution in the construction and industrial sectors are particularly significant. Therefore, the popularization and application of green and environmentally friendly materials have very important practical significance and social benefits. As an innovative environmental protection material, reflective heat-insulating coatings are gradually occupying an important position in the construction and industrial sectors, injecting new vitality into the development of green environmental protection with their excellent heat-insulating effects and energy-saving and environmental protection characteristics.

[0003] Reflective heat-insulating coatings have a wide range of application fields. On buildings, such coatings can significantly reduce the surface temperature of buildings, reduce the energy consumption of refrigeration equipment such as air conditioners, and save operating costs. On outdoor equipment, it reduces the absorption of solar radiation heat, accelerates the dissipation of its own heat, reduces the temperature of the protected object, and extends the service life of the equipment. It helps to reduce the surface temperature and internal temperature of equipment exposed to solar heat radiation, improve the working environment, and enhance safety.

[0004] The traditional technical system mainly relies on hollow glass microspheres to form a vacuum heat-insulating layer, and combines high-refractive-index fillers such as rutile-type titanium dioxide to improve the reflectivity. However, the existing technology has the following core defects:

[0005] Limitations of a single heat-insulating mechanism: Barrier coatings rely on hollow glass microspheres to block heat conduction, but uneven particle size distribution of the microspheres easily leads to coating structure defects and limited ability to inhibit infrared radiation; although reflective coatings can reflect more than 85% of solar heat, they are prone to performance attenuation due to filler agglomeration in high-temperature environments. Summary of the Invention

[0006] The purpose of the present invention is to provide a preparation method of an Al2O3-TiO2 aerogel reflective heat-insulating coating, applying the Al2O3-TiO2 aerogel to the heat-insulating coating to prepare a heat-insulating coating containing Al2O3-TiO2 aerogel, which is applied to application scenarios within 200 °C, has good heat-insulating performance, solves the problem of poor heat-insulating performance of coatings, and has low production cost, and is a high-quality heat-insulating coating.

[0007] In order to achieve the above purpose, the present invention adopts the following technical means:

[0008] The invention provides a reflective heat-insulating coating containing Al2O3-TiO2 aerogel, which comprises, by weight, 100 parts of a compound adhesive, 20-40 parts of Al2O3-TiO2 aerogel, 50-75 parts of hollow glass microspheres, 2-5 parts of microcrystalline cellulose, 2-4 parts of a film-forming agent, 0.5-1.5 parts of a leveling agent, 1.5-3 parts of a quick-drying agent, 0.5-1.5 parts of a thickener, and 0.5-1.5 parts of a wetting agent.

[0009] In the above-mentioned coating, the compound adhesive includes, by mass, 60 to 80 parts of modified silicone acrylic emulsion, 10 to 20 parts of organic silicone emulsion, 10 to 15 parts of acidic silica sol, and 1 to 3 parts of silane coupling agent.

[0010] In the above-mentioned coating, the Al2O3-TiO2 aerogel includes, by mass, 10 to 20 parts of tetrabutyl titanate, 30 to 50 parts of anhydrous ethanol, 5 to 10 parts of Al2O3, 2 to 4 parts of deionized water, 2 to 5 parts of acetic acid, and 0.5 to 1.5 parts of N,N-dimethylformamide (DMF).

[0011] The present invention also provides a method for preparing a reflective heat-insulating coating containing Al2O3-TiO2 aerogel. The method comprises the following steps: 100 parts by mass of a compound adhesive, 20 to 40 parts by mass of Al2O3-TiO2 aerogel, 50 to 75 parts by mass of hollow glass microspheres, 2 to 5 parts by mass of microcrystalline cellulose, 2 to 4 parts by mass of a film-forming agent, 0.5 to 1.5 parts by mass of a leveling agent, 1.5 to 3 parts by mass of a quick-drying agent, 0.5 to 1.5 parts by mass of a thickener, and 0.5 to 1.5 parts by mass of a wetting agent. The above components are added in sequence and dispersed and stirred at high speed for 30 to 60 minutes. Deionized water is added according to the requirements of scraping to adjust the viscosity of the coating to obtain a white viscous Al2O3-TiO2 aerogel reflective heat-insulating coating.

[0012] In the above method, the compound adhesive is calculated by mass fraction: 60-80 parts of modified silicone-acrylic emulsion, 10-20 parts of silicone emulsion, 10-15 parts of acidic silica sol, and 1-3 parts of silane coupling agent. At 50°C, the modified silicone-acrylic emulsion and the silicone emulsion are mixed and stirred, and the silane coupling agent is added dropwise. The pH is adjusted to 4.5-5.5 with acetic acid diluent, and the acidic silica sol is slowly added. Stir for 30 minutes to obtain the compound adhesive. The compound adhesive determines the anti-cracking performance and maximum temperature resistance of the coating. According to product requirements, the coating is naturally dried without cracking, and the maximum temperature resistance is ≥200°C.

[0013] In the above method, the Al2O3-TiO2 aerogel comprises, by weight: 10 to 20 parts of tetrabutyl titanate, 30 to 50 parts of anhydrous ethanol, 5 to 10 parts of Al2O3, 2 to 4 parts of deionized water, 2 to 5 parts of acetic acid, and 0.5 to 1.5 parts of DMF. The Al2O3-TiO2 aerogel is prepared by the following method:

[0014] S1: Slowly add tetrabutyl titanate drop by drop into absolute ethanol and stir well at room temperature to obtain a pale yellow mixed solution, denoted as mixed solution 1;

[0015] S2: Respectively take fumed nano - Al2O3 powder, H2O, absolute ethanol, acetic acid, and DMF and stir vigorously at room temperature to obtain a white mixed solution, denoted as mixed solution 2;

[0016] S3: Use a dropper to slowly add mixed solution 2 drop by drop into mixed solution 1 at a dropping rate of 1 - 2

[0017] mL / min, and stir to make it hydrolyze fully to obtain a uniformly transparent Al2O3 - TiO2 sol;

[0018] S4: At room temperature, let the above - mentioned Al2O3 - TiO2 sol stand for 2 h. The Al2O3 - TiO2 sol gels to obtain an Al2O3 - TiO2 gel. Immerse it in EtOH. The liquid level of EtOH should be about 2 cm higher than the upper surface of the Al2O3 - TiO2 gel, and replace it every 24 h. Repeat this step 3 - 4 times to fully displace the residual water and organic substances in the gel to obtain an Al2O3 - TiO2 wet gel;

[0019] S5: Place the Al2O3 - TiO2 wet gel in the drying kettle of a multi - purpose supercritical test device, add an appropriate amount of absolute ethanol to completely submerge it, and carry out CO2 supercritical drying to obtain an Al2O3 - TiO2 aerogel.

[0020] In the above method, in mixed solution 1 by mass fraction: absolute ethanol is 20 - 30 parts.

[0021] In the above method, in mixed solution 2 by mass fraction: absolute ethanol is 10 - 20 parts.

[0022] In the above method, the CO2 supercritical drying pressure is 10 - 13 MPa, the drying temperature is 40 - 55 °C, and the drying time is 30 - 60 min.

[0023] Because the present invention adopts the above - mentioned technical means, it has the following beneficial effects:

[0024] (1) The present invention adds TiO2 aerogel and dopes fumed nano - Al2O3 powder. By integrating the optical performance advantages of TiO2 and Al2O3, it can reflect infrared wavelengths with obvious thermal effects back; with the high porosity of fumed powder and aerogel, the nano - pores are smaller than the mean free path of air molecules, achieving high - performance heat insulation.

[0025] (2) The present invention uses a compound adhesive instead of simple mixing. By adjusting the pH value, the silane coupling agent is fully hydrolyzed, and the hydrolysis product is silanol, which plays a role in coupling and anchoring, enhancing the bonding strength and adhesion of the adhesive.

[0026] (3) Using an Al2O3-TiO2 aerogel to prepare a heat-insulating coating is suitable for large-scale production, has simple construction conditions, and excellent heat-insulating performance.

[0027] (4) The present invention innovatively combines an Al2O3-TiO2 aerogel (specific surface area > 600 m 2 / g) with hollow glass microspheres (50 - 75 parts). Through the synergistic effect of the aerogel nanopores inhibiting radiative heat transfer and the microspheres blocking convective heat transfer, the thermal conductivity of the coating is reduced to 0.027 W / (m·K). At the same time, a gradient compounding system of a modified silicone-acrylic emulsion (60 - 80 parts) and an organosilicon emulsion (10 - 20 parts) is used, combined with the chemical bonding action of a silane coupling agent (1 - 3 parts), to achieve a high-strength bond at the aerogel-adhesive interface (adhesion ≥ 1.26 MPa). The optimized supercritical CO2 drying process (pressure 10 - 13 MPa, temperature 40 - 55 °C, time 30 - 60 minutes) reduces energy consumption while ensuring that the porosity of the aerogel > 90%, providing long-lasting heat-insulating performance for the coating.

[0028] (5) The reflective heat-insulating coating is a new type of cooling coating that combines reflection, radiation, and heat insulation. The Al2O3-TiO2 aerogel is a nanoporous material with high porosity, low density, high specific surface area, high temperature resistance, and low thermal conductivity. Compared with a pure Al2O3 aerogel, the Al2O3-TiO2 aerogel improves the thermal stability of the aerogel through methods such as in-situ doping modification, deposition modification, organic chain and carbon coating modification, etc. By introducing reinforcing phases such as whiskers, particles, porous skeletons, and fibers, its mechanical properties are significantly improved. At the same time, the light-shielding performance of TiO2 improves the ability of the aerogel to inhibit infrared radiation, significantly reducing the high-temperature thermal conductivity.

[0029] Therefore, combining the ultra-low thermal conductivity of the Al2O3-TiO2 aerogel and its strong ability to inhibit infrared radiation, adding a large amount of Al2O3-TiO2 aerogel to the coating can greatly improve the heat-insulating performance and reflective performance of the coating. Description of the Drawings

[0030] Figure 1 is the SEM image of the Al2O3-TiO2 aerogel;

[0031] Figure 2 is the appearance diagram of the reflective heat-insulating coating containing the Al2O3-TiO2 aerogel;

[0032] Figure 3It is the construction drawing of the Al2O3-TiO2 aerogel reflective heat insulation coating;

[0033] Figure 4 It is the thermal conductivity (25 °C) of Example 1;

[0034] Figure 5 It is the thermal conductivity (25 °C) of Example 2;

[0035] Figure 6 It is the thermal conductivity (25 °C) of Example 3;

[0036] Figure 7 It is the thermal conductivity (25 °C) of the comparative example;

[0037] Figure 8 It is the comparison table of examples. Detailed implementation manners

[0038] The following will give a detailed description of the embodiments of the present invention. Although the present invention will be described and illustrated in conjunction with some specific implementation manners, it should be noted that the present invention is not limited to these implementation manners only. On the contrary, any modifications or equivalent replacements made to the present invention should be covered within the scope of the claims of the present invention.

[0039] In addition, in order to better illustrate the present invention, numerous specific details are given in the following detailed implementation manners. Those skilled in the art will understand that the present invention can be implemented without these specific details.

[0040] Example 1

[0041] This example provides a preparation method of an Al2O3-TiO2 aerogel reflective heat insulation coating, which includes using Al2O3-TiO2 aerogel, compound adhesive, hollow glass microspheres, microcrystalline cellulose, film-forming agent, leveling agent, quick-drying agent, thickening agent, wetting agent, deionized water, and is prepared through high-speed dispersion and stirring steps, including the following steps:

[0042] (1) The compound adhesive includes modified silicone-acrylic emulsion, silicone emulsion, acidic silica sol, and silane coupling agent. By mass fraction: 65 parts of modified silicone-acrylic emulsion, 20 parts of silicone emulsion, 14 parts of acidic silica sol, and 1 part of silane coupling agent. At 50 °C, the modified silicone-acrylic emulsion and the silicone emulsion are mixed and stirred, and the silane coupling agent is added drop by drop. The pH is adjusted to 4.5 with acetic acid (HAc) dilution solution, and the acidic silica sol is slowly added, and stirred for 30 min to obtain the compound adhesive;

[0043] (2) The Al2O3-TiO2 aerogel is prepared by the following method:

[0044] S1: Add 10 parts of tetrabutyl titanate (TBOT) dropwise to 20 parts of absolute ethanol (EtOH), and stir well at room temperature to obtain a light yellow mixed solution, denoted as mixed solution 1.

[0045] S2: Respectively take 5 parts of fumed nano - Al2O3 powder, 2 parts of H2O, 10 parts of EtOH, 2 parts of acetic acid (HAc), and 0.5 part of DMF and add them to another beaker. Stir vigorously at room temperature to obtain a white mixed solution, denoted as mixed solution 2.

[0046] S3: Use a dropper to suck mixed solution 2 and add it dropwise to mixed solution 1 at a dropping rate of 1 - 2 mL / min, and stir to make it hydrolyze fully to obtain a uniformly transparent Al2O3 - TiO2 sol.

[0047] S4: At room temperature, let the above - mentioned Al2O3 - TiO2 sol stand still. The Al2O3 - TiO2 sol gels to obtain an Al2O3 - TiO2 gel. Immerse it in EtOH, and the liquid level of EtOH should be about 2 cm higher than the upper surface of the Al2O3 - TiO2 gel, and change it every 24 h. Repeat this step 3 - 4 times to fully displace the residual water and organic substances in the gel to obtain an Al2O3 - TiO2 wet gel.

[0048] S5: Place the Al2O3 - TiO2 wet gel in the drying kettle of a multi - purpose supercritical test device, and add an appropriate amount of absolute ethanol to completely submerge it, and carry out CO2 supercritical drying. The CO2 supercritical drying pressure is 10 MPa, the drying temperature is 45 °C, and the drying time is 40 min to obtain an Al2O3 - TiO2 aerogel.

[0049] (3) By mass fraction: 100 parts of compound adhesive, 20 parts of Al2O3 - TiO2 aerogel, 71 parts of hollow glass microspheres, 3 parts of microcrystalline cellulose, 3 parts of film - forming agent, 0.5 part of leveling agent, 2.5 parts of quick - drying agent, 0.5 part of thickening agent, 0.5 part of wetting agent. Add the above components in sequence, and disperse and stir at high speed for 30 - 60 min. Adjust the coating viscosity by adding deionized water according to the scraping requirements to obtain a white viscous Al2O3 - TiO2 aerogel reflective heat - insulating coating.

[0050] The thermal conductivity (25 °C) of the Al2O3 - TiO2 aerogel reflective heat - insulating coating is 0.035 W / (m·K), there are no cracks after natural drying at room temperature, and the maximum heat resistance is 245 °C.

[0051] Example 2

[0052] The present embodiment provides a method for preparing a reflective heat-insulating coating containing Al2O3-TiO2 aerogel, comprising using Al2O3-TiO2 aerogel, compound adhesive, hollow glass microspheres, microcrystalline cellulose, film-forming agent, leveling agent, quick-drying agent, thickener, wetting agent, and deionized water, and preparing the coating through high-speed dispersion and stirring steps, comprising the following steps:

[0053] (1) The composite adhesive comprises a modified silicone-acrylic emulsion, an organic silicone emulsion, an acidic silica sol, and a silane coupling agent, wherein the weight fractions are as follows: 68 parts of the modified silicone-acrylic emulsion, 18 parts of the organic silicone emulsion, 12 parts of the acidic silica sol, and 2 parts of the silane coupling agent. The modified silicone-acrylic emulsion and the organic silicone emulsion are mixed and stirred at 50° C. The silane coupling agent is added dropwise, the pH is adjusted to 5.0 with an acetic acid (HAc) diluent, the acidic silica sol is slowly added, and the mixture is stirred for 30 minutes to obtain a composite adhesive;

[0054] (2) The Al2O3-TiO2 aerogel is prepared by the following method:

[0055] S1: 15 parts of tetrabutyl titanate (TBOT) were added dropwise into 30 parts of anhydrous ethanol (EtOH), and the mixture was stirred at room temperature to obtain a light yellow mixed solution, which was recorded as mixed solution 1;

[0056] S2: Take 10 parts of gas phase nano-Al2O3 powder, 3 parts of H2O, 12 parts of EtOH, 3 parts of acetic acid (HAc) and 1 part of DMF respectively and add them into another beaker, stir them vigorously at room temperature to obtain a white mixed solution, which is recorded as mixed solution 2;

[0057] S3: Use a dropper to draw mixed solution 2 and add it dropwise into mixed solution 1 at a dropping rate of 1-2 mL / min, and stir it to fully hydrolyze it to obtain a uniform and transparent Al2O3-TiO2 sol.

[0058] S4: At room temperature, the Al2O3-TiO2 sol is allowed to stand, and the Al2O3-TiO2 sol is gelled to obtain Al2O3-TiO2 gel. It is then soaked in EtOH, the liquid level of which needs to be about 2 cm higher than the upper surface of the Al2O3-TiO2 gel, and replaced every 24 hours. This step is repeated 3-4 times to fully displace the residual water and organic matter in the gel, and Al2O3-TiO2 wet gel is obtained;

[0059] S5: Place the Al2O3-TiO2 wet gel in a drying kettle of a multi-purpose supercritical test device, add an appropriate amount of anhydrous ethanol to completely submerge it, and perform CO2 supercritical drying. The CO2 supercritical drying pressure is 11 MPa, the drying temperature is 45°C, and the drying time is 45 min to obtain Al2O3-TiO2 aerogel.

[0060] (3) By mass fraction: 100 parts of the compound adhesive, 35 parts of Al2O3-TiO2 aerogel, 51.5 parts of hollow glass microspheres, 5 parts of microcrystalline cellulose, 4 parts of film-forming agent, 1.0 part of leveling agent, 1.5 parts of quick-drying agent, 1.0 part of thickening agent, 1.0 part of wetting agent. Add the above components in sequence, disperse and stir at high speed for 30 - 60 min, and adjust the coating viscosity by adding deionized water according to the doctor blade coating requirement to obtain a white viscous Al2O3-TiO2 aerogel reflective heat insulation coating.

[0061] The thermal conductivity (25 °C) of the Al2O3-TiO2 aerogel reflective heat insulation coating is 0.027 W / (m·K), there are no cracks after natural drying at room temperature, and the maximum heat resistance is 220 °C.

[0062] Example 3

[0063] This example provides a preparation method of an Al2O3-TiO2 aerogel reflective heat insulation coating, which includes using Al2O3-TiO2 aerogel, compound adhesive, hollow glass microspheres, microcrystalline cellulose, film-forming agent, leveling agent, quick-drying agent, thickening agent, wetting agent, and deionized water, and is prepared through high-speed dispersion and stirring steps, including the following steps:

[0064] (1) The compound adhesive contains modified silicon-acrylic emulsion, silicone emulsion, acidic silica sol, and silane coupling agent. By mass fraction: 75 parts of modified silicon-acrylic emulsion, 11 parts of silicone emulsion, 11 parts of acidic silica sol, 3 parts of silane coupling agent. At 50 °C, mix and stir the modified silicon-acrylic emulsion and the silicone emulsion, dropwise add the silane coupling agent, adjust the pH to 5.5 with acetic acid (HAc) dilution solution, and slowly add the acidic silica sol, and stir for 30 min to obtain the compound adhesive;

[0065] (2) The Al2O3-TiO2 aerogel is prepared by the following method:

[0066] S1: Dropwise add 18 parts of tetrabutyl titanate (TBOT) into 25 parts of absolute ethanol (EtOH) and stir well at room temperature to obtain a light yellow mixed solution, denoted as mixed solution 1;

[0067] S2: Respectively take 8 parts of fumed nano-Al2O3 powder, 4 parts of H2O, 15 parts of EtOH, 3 parts of acetic acid (HAc), and 1.5 parts of DMF and add them into another beaker, and stir strongly at room temperature to obtain a white mixed solution, denoted as mixed solution 2;

[0068] S3: Use a dropper to slowly add mixed solution 2 drop by drop into mixed solution 1 at a dropping rate of 1 - 2 mL / min, and stir to make it hydrolyze fully to obtain a uniformly transparent Al2O3-TiO2 sol.

[0069] S4: At room temperature, let the above-mentioned Al2O3-TiO2 sol stand still. The Al2O3-TiO2 sol gels to obtain an Al2O3-TiO2 gel. Immerse it in EtOH. The liquid level of EtOH should be about 2 cm higher than the upper surface of the Al2O3-TiO2 gel, and change it every 24 h. Repeat this step 3-4 times to fully displace the residual moisture and organic substances in the gel, and obtain an Al2O3-TiO2 wet gel;

[0070] S5: Place the Al2O3-TiO2 wet gel in the drying kettle of a multi-purpose supercritical test device, and add an appropriate amount of absolute ethanol to completely submerge it. Perform CO2 supercritical drying. The CO2 supercritical drying pressure is 12 MPa, the drying temperature is 55 °C, and the drying time is 35 min to obtain an Al2O3-TiO2 aerogel.

[0071] (3) By mass fraction: 100 parts of the compound adhesive, 30 parts of the Al2O3-TiO2 aerogel, 58.5 parts of hollow glass microspheres, 4 parts of microcrystalline cellulose, 3 parts of film-forming agent, 1.0 part of leveling agent, 1.5 parts of quick-drying agent, 1.0 part of thickening agent, 1.0 part of wetting agent. Add the above components in sequence and stir at high speed for 30-60 min. Adjust the coating viscosity by adding deionized water according to the scraping requirements to obtain a white viscous Al2O3-TiO2 aerogel reflective heat insulation coating.

[0072] The thermal conductivity (25 °C) of the Al2O3-TiO2 aerogel reflective heat insulation coating is 0.030 W / (m·K). It has no cracks after natural drying at room temperature and the highest heat resistance is 205 °C.

[0073] Example 4

[0074] Compared with Example 1, the preparation processes of the compound adhesive and the Al2O3-TiO2 aerogel are the same. The difference is that the coating formula of Example 1 is replaced with the coating formula of Example 2.

[0075] The thermal conductivity (25 °C) of the Al2O3-TiO2 aerogel reflective heat insulation coating is 0.030 W / (m·K). It has no cracks after natural drying at room temperature and the highest heat resistance is 245 °C.

[0076] Example 5

[0077] Compared with Example 3, the preparation processes of the compound adhesive and the Al2O3-TiO2 aerogel are the same. The difference is that the coating formula of Example 3 is replaced with the coating formula of Example 2.

[0078] The thermal conductivity (25 °C) of the Al2O3-TiO2 aerogel reflective heat insulation coating is 0.028 W / (m·K). It has no cracks after natural drying at room temperature and the highest heat resistance is 205 °C.

[0079] Example 6

[0080] Compared with Example 3, the preparation processes of the compound adhesive and the Al2O3-TiO2 aerogel are the same. The differences are as follows: the coating formulation in Example 3 is replaced with the coating formulation in Example 2, and the dosage of the compound adhesive in the coating formulation is replaced with 60 parts.

[0081] The Al2O3-TiO2 aerogel reflective heat-insulating coating cracks during natural drying at room temperature, and the thermal conductivity (25 °C) and the maximum heat resistance cannot be measured.

[0082] Comparative Example

[0083] This comparative example provides a method for preparing a heat-insulating coating, which includes using a compound adhesive, hollow glass microspheres, microcrystalline cellulose, a film-forming agent, a leveling agent, a quick-drying agent, a thickening agent, a wetting agent, and deionized water, and preparing through high-speed dispersion and stirring steps, including the following steps:

[0084] (1) The compound adhesive is the same as that in Example 2;

[0085] (2) By mass fraction: 100 parts of the compound adhesive, 86.5 parts of hollow glass microspheres, 5 parts of microcrystalline cellulose, 4 parts of the film-forming agent, 1.0 part of the leveling agent, 1.5 parts of the quick-drying agent, 1.0 part of the thickening agent, and 1.0 part of the wetting agent. Add the above components in sequence, disperse and stir at high speed for 30-60 min, and adjust the coating viscosity by adding deionized water according to the scraping requirements to obtain a white viscous heat-insulating coating.

[0086] The thermal conductivity (25 °C) of this heat-insulating coating is 0.045 W / (m·K), there are no cracks during natural drying at room temperature, and the maximum heat resistance is 220 °C.

Claims

1. A heat-reflective and insulating coating containing Al2O3-TiO2 aerogel, characterized in that, By mass fraction, it includes 100 parts of compound adhesive, 20 - 40 parts of Al2O3-TiO2 aerogel, 50 - 75 parts of hollow glass microspheres, 2 - 5 parts of microcrystalline cellulose, 2 - 4 parts of film-forming agent, 0.5 - 1.5 parts of leveling agent, 1.5 - 3 parts of quick-drying agent, 0.5 - 1.5 parts of thickening agent, and 0.5 - 1.5 parts of wetting agent.

2. The coating according to claim 1, characterized in that, The compound adhesive by mass fraction includes: 60 - 80 parts of modified silicone-acrylic emulsion, 10 - 20 parts of silicone emulsion, 10 - 15 parts of acidic silica sol, and 1 - 3 parts of silane coupling agent.

3. The coating according to claim 1, characterized in that, The Al2O3-TiO2 aerogel by mass fraction includes: 10 - 20 parts of tetrabutyl titanate, 30 - 50 parts of absolute ethanol, 5 - 10 parts of Al2O3, 2 - 4 parts of deionized water, 2 - 5 parts of acetic acid, and 0.5 - 1.5 parts of N,N-dimethylformamide (DMF).

4. A preparation method of an Al2O3-TiO2 aerogel reflective heat insulation coating, characterized in that, By mass fraction, 100 parts of compound adhesive, 20 - 40 parts of Al2O3-TiO2 aerogel, 50 - 75 parts of hollow glass microspheres, 2 - 5 parts of microcrystalline cellulose, 2 - 4 parts of film-forming agent, 0.5 - 1.5 parts of leveling agent, 1.5 - 3 parts of quick-drying agent, 0.5 - 1.5 parts of thickening agent, and 0.5 - 1.5 parts of wetting agent. Add the above components in sequence, disperse and stir at high speed for 30 - 60 min, and adjust the coating viscosity by adding deionized water according to the doctor blade coating requirement to obtain the white viscous Al2O3-TiO2 aerogel reflective heat insulation coating.

5. The preparation method according to claim 1, characterized in that, The compound adhesive by mass fraction: 60 - 80 parts of modified silicone-acrylic emulsion, 10 - 20 parts of silicone emulsion, 10 - 15 parts of acidic silica sol, and 1 - 3 parts of silane coupling agent. At 50 °C, mix and stir the modified silicone-acrylic emulsion and the silicone emulsion, dropwise add the silane coupling agent, adjust the pH to 4.5 - 5.5 with acetic acid diluent, and slowly add the acidic silica sol, and stir for 30 min to obtain the compound adhesive.

6. The preparation method according to claim 1, characterized in that, The Al2O3-TiO2 aerogel by mass fraction includes: 10 - 20 parts of tetrabutyl titanate, 30 - 50 parts of absolute ethanol, 5 - 10 parts of Al2O3, 2 - 4 parts of deionized water, 2 - 5 parts of acetic acid, and 0.5 - 1.5 parts of DMF. The Al2O3-TiO2 aerogel is prepared by the following method: S1: Dropwise add tetrabutyl titanate into absolute ethanol, and stir well at room temperature to obtain a light yellow mixed solution, denoted as mixed solution 1; S2: Respectively take fumed nano-Al2O3 powder, H2O, absolute ethanol, acetic acid, and DMF, and stir strongly at room temperature to obtain a white mixed solution, denoted as mixed solution 2; S3: Use a dropper to suck mixed solution 2 and dropwise add it into mixed solution 1 at a dropping rate of 1 - 2 mL / min, and stir to make it hydrolyze fully to obtain a uniformly transparent Al2O3-TiO2 sol; S4: At room temperature, leave the above-mentioned Al2O3-TiO2 sol to stand for 2 h. The Al2O3-TiO2 sol gels to obtain an Al2O3-TiO2 gel. Immerse it in EtOH. The liquid level of EtOH should be about 2 cm higher than the upper surface of the Al2O3-TiO2 gel, and change it every 24 h. Repeat this step 3 - 4 times to fully displace the residual water and organic substances in the gel, obtaining an Al2O3-TiO2 wet gel; S5: Place the Al2O3-TiO2 wet gel in the drying kettle of a multi-purpose supercritical test device, add an appropriate amount of absolute ethanol to completely submerge it, and carry out CO2 supercritical drying to obtain an Al2O3-TiO2 aerogel.

7. The preparation method according to claim 1, characterized in that, Mixture 1, by mass fraction: 20 - 30 parts of absolute ethanol.

8. The preparation method according to claim 1, wherein, Mixture 2, by mass fraction: 10 - 20 parts of absolute ethanol.

9. The preparation method according to claim 1, wherein, CO2 supercritical drying pressure is 10 - 13 MPa, drying temperature is 40 - 55 °C, and drying time is 30 - 60 min.

Images