Outer wall light radiation heat preservation and insulation decorative plate and preparation method thereof

Abstract

The invention relates to the field of coatings, and discloses an outer wall light radiation heat preservation and heat insulation decorative sheet and a preparation method thereof.A radiation refrigeration layer on the surface of the outer wall light radiation heat preservation and heat insulation decorative sheet comprises modified acrylate resin, silicon dioxide, ground calcium carbonate, talcum powder, modified hollow glass beads and auxiliaries; the modified acrylate resin is prepared by copolymerizing perfluorooctyl ethyl acrylate, methyl methacrylate, modified isocyano ethyl methacrylate and vinyltriethoxysilane, and the modified isocyano ethyl methacrylate is prepared by using salicylaldehyde and benzothiazole-2-formaldehyde as well as 1, 2, 4-trimethyl-1, 3-pentanediol monoisobutyrate as an initiator and using 2, 3, 4-trimethyl-1, 3-pentanediol monoisobutyrate as an initiator. The preparation method comprises the following steps: reacting amino groups at two ends of 1, 5-naphthylenediamine with DOPO, carrying out nucleophilic addition reaction with DOPO, and grafting with isocyano ethyl methacrylate. The modified hollow glass beads are prepared by using tetrabutyl titanate as a titanium source through a sol-gel method, and the prepared radiation refrigeration layer has the super-amphiphobic self-cleaning effect, the radiation refrigeration effect is good, and meanwhile the flame retardant property and the antibacterial effect are excellent.

Description

Technical Field

[0001] The invention belongs to the technical field of coatings, and in particular relates to a lightweight radiation thermal insulation decorative board for an exterior wall and a preparation method thereof. Background Art

[0002] With the development of economy and the improvement of living standards, energy consumption is increasing day by day, and the demand for refrigeration is more urgent. As we all know, all objects on the earth continue to absorb various heat from the outside world, such as solar heat and thermal radiation; at the same time, all objects continue to emit heat to the outside in the form of infrared radiation. This is the principle that infrared thermometers can measure temperature in vitro and infrared detectors can detect targets. Radiative cooling is a passive cooling technology that does not require electricity or refrigerants as heat transfer media. It can also dissipate the heat of a specific internal space into the cold space outside the atmosphere in the form of infrared radiation.

[0003] As we all know, the heat exchange between the building envelope and the surrounding environment and the sun can greatly affect the thermal comfort of the indoor space. In order to meet the thermal comfort needs of buildings, people have adopted a variety of methods to improve the energy efficiency of building envelopes, including reflective materials, thermal insulation materials, etc. Among them, architectural coatings, as a non-structural solution, have attracted more and more attention due to their convenience of construction and large-scale applicability. Among them, radiant cooling coatings have the advantages of no pollution and no emissions compared to traditional refrigeration methods, which is of great significance to energy conservation, emission reduction and achieving carbon neutrality. However, the existing radiant cooling coating technology faces the challenges of wind, rain and dust pollution due to its long-term outdoor working environment, which will cause the destruction of spectral performance, thereby greatly weakening the radiant cooling performance and even shortening its service life. In addition, most radiant cooling coatings prepared based on organic matter have poor flame retardancy, antibacterial properties and durability, making it difficult to achieve long-term and safe cooling. Summary of the invention

[0004] In order to solve the deficiencies mentioned in the above background technology, the purpose of the present invention is to provide a lightweight radiation thermal insulation decorative panel for exterior walls and a preparation method thereof. The prepared radiation cooling layer has super-amphiphobic self-cleaning effect, good radiation cooling effect, and excellent flame retardant and antibacterial effects.

[0005] The purpose of the present invention can be achieved through the following technical solutions: A lightweight radiation thermal insulation decorative board for an exterior wall, comprising a substrate and a radiation cooling layer on the surface of the substrate, wherein the radiation cooling layer comprises the following components in parts by weight: 40-60 parts of a modified acrylic resin, 10-20 parts of silicon dioxide, 10-20 parts of heavy calcium carbonate, 4-7 parts of talcum powder, 10-20 parts of modified hollow glass microspheres, 1.5-2 parts of a film-forming aid, 1-2 parts of a defoaming agent, 0.2-0.5 parts of a leveling agent, and 5-15 parts of an organic solvent; The modified acrylic resin is prepared by copolymerizing perfluorooctylethyl acrylate, methyl methacrylate, modified isocyanoethyl methacrylate and vinyl triethoxysilane, wherein the modified isocyanoethyl methacrylate is prepared by using salicylaldehyde and benzothiazole-2-carboxaldehyde to react with the amino groups at both ends of 1,5-naphthalenediamine to obtain a Schiff base monomer, and then DOPO and the Schiff base monomer undergo a nucleophilic addition reaction and then are grafted with isocyanoethyl methacrylate; the modified hollow glass microspheres are prepared by using anhydrous ethanol as a solvent, n-butyl titanate as a titanium source, and glacial acetic acid as a chelating agent, and adopting a sol-gel method.

[0006] Preferably, the substrate is any one of an iron plate, a copper plate, a stainless steel plate, an aluminum plate, an asbestos-free fiber cement plate, a UHPC plate, a ceramic plate, and a clay plate.

[0007] Preferably, the film-forming aid is any one of propylene glycol methyl ether or ethylene glycol butyl ether; the defoaming agent is any one of fatty alcohol polyoxyethylene ether or alkylphenol polyoxyethylene ether; the leveling agent is sodium polyacrylate; and the organic solvent is acetone.

[0008] Preferably, the preparation method of the modified acrylate resin comprises the following steps: (1) salicylaldehyde, 1,5-naphthalenediamine and benzothiazole-2-carboxaldehyde are placed in a reactor, anhydrous ethanol solvent is added, the mixture is stirred evenly, glacial acetic acid is added dropwise, and the mixture is stirred at 65-80° C. for 4-5 hours. After the reaction is completed, the mixture is filtered, washed and dried to prepare a Schiff base monomer; (2) Putting a Schiff base monomer into a reactor, adding anhydrous ethanol solvent and DOPO, stirring and reacting at 75-85°C for 6-8 hours, filtering, washing and drying after the reaction is completed to prepare a DOPO derivative; (3) Put DOPO derivative, isocyanoethyl methacrylate and dibutyltin dilaurate in a reactor, add acetone solvent, raise the temperature to 45-50°C, stir and react for 10-12 hours, and after the reaction is completed, perform rotary evaporation, wash and dry to prepare modified isocyanoethyl methacrylate; (4) Perfluorooctyl ethyl acrylate, methyl methacrylate, modified isocyanoethyl methacrylate and vinyl triethoxysilane are placed in a reactor, acetone solvent is added and stirred evenly, nitrogen is passed through the reaction, azobisisobutyronitrile initiator is added, and the mixture is stirred and reacted at 55-70°C for 6-8 hours to prepare a modified acrylate resin.

[0009] Preferably, in step (1), the molar ratio of salicylaldehyde, 1,5-naphthalenediamine and benzothiazole-2-carboxaldehyde is 1-1.2:1:1-1.2.

[0010] Preferably, in step (2), the molar ratio of the Schiff base monomer to DOPO is 1:2-2.3.

[0011] Preferably, in step (3), the molar ratio of the DOPO derivative to isocyanoethyl methacrylate is 1:1-1.2.

[0012] Preferably, in step (4), the molar ratio of perfluorooctylethyl acrylate, methyl methacrylate, modified isocyanoethyl methacrylate and vinyl triethoxysilane is 2-6:2-6:1-2:1; the structural formula of modified isocyanoethyl methacrylate in step (4) is as follows: .

[0013] Preferably, the preparation method of the modified hollow glass microspheres comprises the following steps: taking anhydrous ethanol, tetrabutyl titanate and glacial acetic acid and mixing them evenly to obtain solution one, taking anhydrous ethanol and deionized water and mixing them evenly to obtain solution two, adding solution two dropwise into solution one under stirring, and adjusting the pH value of the system to 3-4, stirring the reaction for 0.5-1h, then adding hollow glass microspheres, continuing to stir for 1-1.5h, standing and aging for 10-12h and then drying, and calcining at 500-550°C for 3-4h to prepare modified hollow glass microspheres.

[0014] A method for preparing a lightweight radiation thermal insulation decorative panel for an exterior wall comprises the following steps: S1. Weigh each component by weight; S2, dispersing the modified acrylic resin in an organic solvent to obtain a dispersion, then adding the modified hollow glass microspheres, stirring evenly at 70-80° C., then heating to 100-120° C., stirring and reacting for 2-4 hours, to obtain a composite acrylic resin; S3, pouring the composite acrylic resin, silicon dioxide, heavy calcium carbonate, talcum powder, film-forming aid, defoaming agent and leveling agent into a mixer, stirring and mixing thoroughly to obtain a radiation refrigeration layer; S4. The radiation cooling layer is evenly coated on the surface of the substrate, and after thermal drying and curing, a lightweight radiation thermal insulation decorative panel for the exterior wall is prepared.

[0015] Beneficial effects of the present invention: The present invention uses anhydrous ethanol as a solvent, n-butyl titanate as a titanium source, and glacial acetic acid as a chelating agent, and adopts a sol-gel method to prepare a modified hollow glass microsphere coated with titanium dioxide, thereby improving the surface roughness of the hollow glass microsphere, wherein the hollow structure of the hollow glass microsphere makes it have the characteristics of low thermal conductivity and good thermal insulation effect, and titanium dioxide has the characteristics of large refractive index and high reflectivity to sunlight, and titanium dioxide is coated on the surface of the hollow glass microsphere to achieve the optical properties and thermal insulation functions of the two complement each other. At the same time, the present invention uses salicylaldehyde and benzothiazole-2-carboxaldehyde to react with the amino groups at both ends of 1,5-naphthalene diamine to prepare a Schiff base monomer, and then uses the PH bond in the DOPO structure to react with the two formed -CH=N- groups to react with nucleophilic addition to prepare a DOPO derivative, and then uses the hydroxyl group introduced in the DOPO derivative structure to react with the isocyanate group in the isocyanoethyl methacrylate structure to react with nucleophilic addition to prepare a modified isocyanoethyl methacrylate containing a double bond group.

[0016] The present invention uses perfluorooctyl ethyl acrylate, methyl methacrylate, modified isocyanoethyl methacrylate and vinyl triethoxysilane as polymerization monomers to prepare a modified acrylic resin, wherein the perfluorooctyl ethyl acrylate provides a fluorocarbon chain as a hydrophobic and oleophobic group, the methyl methacrylate improves the solubility of the modified acrylic resin in an acetone solvent and adjusts the film-forming property of the modified acrylic resin, the modified isocyanoethyl methacrylate provides a thiazole monomer with antibacterial activity and nitrogen and phosphorus elements with a synergistic flame retardant effect, the vinyl triethoxysilane provides a siloxane group, introduces a reaction binding site, and undergoes a condensation reaction with a hydroxyl group on the surface of a modified hollow glass microbead, and the modified acrylic resin is adsorbed on the surface of the modified hollow glass microbead by grafting to prepare a composite acrylic resin, thereby preparing a super-hydrophobic and super-oleophobic radiation refrigeration layer, thereby producing an anti-fouling and self-cleaning effect, and can effectively alleviate the problem that the passive radiation refrigeration coating has reduced passive radiation refrigeration performance due to environmental pollution.

[0017] The radiation cooling layer prepared by the present invention has a passive radiation cooling effect in which the surface temperature is lower than the ambient temperature under direct sunlight and a super-amphiphobic self-cleaning effect. The solar reflectivity of the radiation cooling layer can reach 98.6%, the overall infrared emissivity can reach 95.0%, and the atmospheric window selective infrared emissivity can reach 99.1%. Therefore, it is easy to achieve a cooling phenomenon in which the heat emitted is greater than the heat absorbed, and the surface temperature is lower than the ambient temperature. The radiation cooling layer is applied to the surface of a lightweight radiation thermal insulation decorative panel for an exterior wall, thereby preparing a finished panel with radiation cooling, thermal insulation and decoration. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 is an infrared spectrum of the DOPO derivative prepared in Example 1 of the present invention; Figure 2 It is the infrared spectrum of the hollow glass microspheres before and after modification in Example 2 of the present invention. DETAILED DESCRIPTION

[0020] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] Example 1 A method for preparing a modified acrylic resin comprises the following steps: (1) 1.4 g of salicylaldehyde, 1.6 g of 1,5-naphthalenediamine and 1.7 g of benzothiazole-2-carboxaldehyde were placed in a reactor, 50 mL of anhydrous ethanol solvent was added, two drops of glacial acetic acid were added after stirring evenly, and the mixture was stirred at 75° C. for 4 h. After the reaction was completed, the mixture was filtered, washed and dried to prepare a Schiff base monomer; (2) 4 g of Schiff base monomer (Mr = 407.5) was placed in a reactor, 100 mL of anhydrous ethanol solvent and 4.3 g of DOPO were added, and the mixture was stirred at 80 °C for 7 h. After the reaction was completed, the mixture was filtered, washed, and dried to obtain a DOPO derivative; (3) 4.2 g of DOPO derivative (Mr = 839.8), 1.6 g of isocyanoethyl methacrylate and a drop of dibutyltin dilaurate were placed in a reactor, 50 mL of acetone solvent was added, the temperature was raised to 50 ° C, and the reaction was stirred for 12 h. After the reaction was completed, the modified isocyanoethyl methacrylate was prepared by rotary evaporation, washing and drying; (4) Take 20.7 g of perfluorooctyl ethyl acrylate, 4 g of methyl methacrylate, 9.9 g of modified isocyanoethyl methacrylate and 1.9 g of vinyl triethoxysilane in a reactor, add 100 mL of acetone solvent and stir evenly, pass nitrogen through the reaction, add 0.6 g of azobisisobutyronitrile initiator, place it at 65 ° C and stir for 8 h to prepare a modified acrylate resin.

[0022] The DOPO derivatives were analyzed by infrared spectroscopy, and the results are as follows: Figure 1 As shown, the DOPO infrared spectrum has the following characteristic peaks: 932cm -1 、1213cm -1 (PO-CAr), 1246cm -1 (P=O), 1477cm -1 、1580cm -1 (P-CAr), 2436cm -1 (PH), the C=N bond of the Schiff base imine structure appears at 1618 cm-1 in the Schiff base monomer curve -1 In the DOPO derivative curve, no C=N characteristic peak and PH characteristic peak were observed, and the 932cm -1 、1213cm -1 (PO-CAr), 1246cm -1 (P=O), 1477cm -1 、1580cm -1 The characteristic peaks of (P-CAr) all exist, indicating that DOPO derivatives were successfully synthesized.

[0023] Example 2 A method for preparing modified hollow glass microspheres comprises the following steps: Take 40 mL of anhydrous ethanol, 10 mL of tetrabutyl titanate and 3 mL of glacial acetic acid and mix them evenly to obtain solution 1. Take 20 mL of anhydrous ethanol and 5 mL of deionized water and mix them evenly to obtain solution 2. Solution 2 is added dropwise to solution 1 under stirring, and the pH value of the system is adjusted to 4. The reaction is stirred for 1 hour, and then 2 g of hollow glass microspheres are added. The stirring is continued for 1 hour. After standing for 12 hours, it is dried and placed at 550°C for calcination for 4 hours to prepare modified hollow glass microspheres.

[0024] The modified hollow glass microspheres were analyzed by infrared spectroscopy, and the results are as follows: Figure 2 As shown, the five main absorption peaks are located at 463 cm -1 、793cm -1 、1155cm -1 、1401cm -1 、3445cm -1 At 2003 cm-1, the modified hollow glass microspheres have a new absorption peak, which corresponds to the bending vibration, symmetric expansion vibration and asymmetric stretching vibration of silicon oxygen bond (Si-O-Si), deformation vibration of hydroxyl (OH), and stretching vibration of silicon hydroxyl (Si-OH). Compared with the hollow glass microspheres, the modified hollow glass microspheres have a new absorption peak at 2003 cm-1. -1 The weak peak at 2193 cm -1The Si-O-Ti bond vibration at the position indicated that titanium dioxide was combined with the surface of hollow glass microspheres through Si-O-Ti bonds, and the modified hollow glass microspheres were successfully prepared.

[0025] Example 3 A radiation cooling layer comprises the following components in parts by weight: 42 parts of the modified acrylate resin prepared in Example 1, 10 parts of silicon dioxide, 10 parts of heavy calcium carbonate, 4 parts of talc, 10 parts of the modified hollow glass microspheres prepared in Example 2, 1.5 parts of film-forming aid propylene glycol methyl ether, 1 part of defoaming agent fatty alcohol polyoxyethylene ether, 0.2 parts of leveling agent sodium polyacrylate, and 7 parts of organic solvent acetone.

[0026] A method for preparing a lightweight radiation thermal insulation decorative panel for an exterior wall comprises the following steps: S1. Weigh each component by weight; S2, dispersing the modified acrylic resin in acetone to obtain a dispersion, then adding the modified hollow glass microspheres, stirring evenly at 75° C., then heating to 110° C., stirring and reacting for 3 hours to obtain a composite acrylic resin; S3, pouring the composite acrylic resin, silicon dioxide, heavy calcium carbonate, talcum powder, film-forming aid, defoaming agent and leveling agent into a mixer, stirring and mixing thoroughly to obtain a radiation refrigeration layer; S4. The radiation cooling layer is evenly coated on the surface of the asbestos-free fiber cement board, and after heat drying and curing, a lightweight radiation thermal insulation decorative board for the exterior wall is prepared.

[0027] Example 4 A radiation cooling layer comprises the following components in parts by weight: 47 parts of the modified acrylate resin prepared in Example 1, 14 parts of silicon dioxide, 12 parts of heavy calcium carbonate, 5 parts of talc, 15 parts of the modified hollow glass microspheres prepared in Example 2, 2 parts of film-forming aid ethylene glycol butyl ether, 1.5 parts of defoaming agent alkylphenol polyoxyethylene ether, 0.4 parts of leveling agent sodium polyacrylate, and 10 parts of organic solvent acetone.

[0028] The preparation method of a lightweight radiation thermal insulation decorative panel for an exterior wall is the same as that of Example 3.

[0029] Example 5 A radiation cooling layer comprises the following components in parts by weight: 55 parts of the modified acrylate resin prepared in Example 1, 17 parts of silicon dioxide, 16 parts of heavy calcium carbonate, 6.5 parts of talc, 18 parts of the modified hollow glass microspheres prepared in Example 2, 2 parts of film-forming aid propylene glycol methyl ether, 2 parts of defoaming agent fatty alcohol polyoxyethylene ether, 0.5 parts of leveling agent sodium polyacrylate, and 14 parts of organic solvent acetone.

[0030] The preparation method of a lightweight radiation thermal insulation decorative panel for an exterior wall is the same as that of Example 3.

[0031] Comparative Example 1 A method for preparing a modified acrylic resin comprises the following steps: Take perfluorooctyl ethyl acrylate, methyl methacrylate, isocyanoethyl methacrylate and vinyl triethoxysilane in a reactor, add acetone solvent and stir evenly, pass nitrogen through the reaction, add azobisisobutyronitrile initiator, place it at 55~70℃ and stir for 6~8h to prepare a modified acrylate resin.

[0032] Comparative Example 2 A radiation cooling layer comprises the following components in parts by weight: 55 parts of modified acrylate resin prepared in Comparative Example 1, 17 parts of silicon dioxide, 16 parts of heavy calcium carbonate, 6.5 parts of talc, 18 parts of modified hollow glass microspheres prepared in Example 2, 2 parts of film-forming aid propylene glycol methyl ether, 2 parts of defoaming agent fatty alcohol polyoxyethylene ether, 0.5 parts of leveling agent sodium polyacrylate, and 14 parts of organic solvent acetone.

[0033] The preparation method of a lightweight radiation thermal insulation decorative panel for an exterior wall is the same as that of Example 3.

[0034] Comparative Example 3 A radiation cooling layer comprises the following components in parts by weight: 55 parts of the modified acrylic resin prepared in Example 1, 17 parts of silicon dioxide, 16 parts of heavy calcium carbonate, 6.5 parts of talc, 18 parts of hollow glass microspheres, 2 parts of film-forming aid propylene glycol methyl ether, 2 parts of defoaming agent fatty alcohol polyoxyethylene ether, 0.5 parts of leveling agent sodium polyacrylate, and 14 parts of organic solvent acetone.

[0035] The preparation method of a lightweight radiation thermal insulation decorative panel for an exterior wall is the same as that of Example 3.

[0036] Performance Testing The performance of the radiation refrigeration layer prepared in Examples 3-5 and Comparative Examples 2-3 was tested: a contact angle tester was used to test the static contact angle of water and the static contact angle of n-hexadecane; the antibacterial rate was tested with reference to GB / T 21866-2008, and the test bacteria was Staphylococcus aureus; the flame retardant performance was tested by the limiting oxygen index; the solar reflectivity, overall infrared emissivity and atmospheric window selective infrared emissivity were commissioned to the National Building Materials Testing Center for testing. The higher the solar reflectivity, the less solar heat absorbed during the day, the higher the overall infrared emissivity or the atmospheric window selective infrared emissivity value, and the stronger the self-heat dissipation capacity; the data results are shown in Table 1.

[0037] Table 1 Test results of sample performance ; From the data in Table 1, it can be seen that the radiation cooling layer prepared in Examples 3-5 of the present invention has a super-double-repellent self-cleaning effect, the solar reflectivity can reach 98.3~98.6%, the overall infrared emissivity can reach 94.1~95.0%, and the atmospheric window selective infrared emissivity can reach 98.7~99.1%, and the flame retardant performance and antibacterial effect are excellent. Among them, in Comparative Example 2, isocyanoethyl methacrylate was not modified, and the measured antibacterial rate and limiting oxygen index of Escherichia coli were lower than those of Examples 3-5. The reason is that the thiazole monomer with antibacterial activity and the nitrogen and phosphorus elements with synergistic flame retardant effects were not introduced. In Comparative Example 3, the hollow glass microspheres were not coated and modified, and the measured contact angle was lower than that of Examples 3-5, and the double super-repellent surface was not achieved. The possible reason is that the coating modification increased the surface roughness of the hollow glass microspheres, and in the subsequent process, the modified acrylic resin Grafting causes the coating to reach a super-hydrophobic and super-oleophobic state, and the measured solar reflectivity, overall infrared emissivity, and atmospheric window selectivity (8~13μm) infrared emissivity are lower than those in Example 3-5. The reason is that the coated modified hollow glass microspheres have strong reflection and refraction of sunlight, and the strong absorption of Ti-O bonds and Si-O bonds in the corresponding wave number range of the atmospheric window enhances the emissivity of the coating. In addition, the antibacterial rate of Escherichia coli is lower than that in Example 3-5, indicating that the introduction of titanium dioxide improves the antibacterial effect to a certain extent.

[0038] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0039] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. A lightweight radiation thermal insulation decorative panel for exterior walls, characterized in that: The invention comprises a substrate and a radiation cooling layer on the surface of the substrate, wherein the radiation cooling layer comprises the following components in parts by weight: 40-60 parts of modified acrylic resin, 10-20 parts of silicon dioxide, 10-20 parts of heavy calcium carbonate, 4-7 parts of talc, 10-20 parts of modified hollow glass microspheres, 1.5-2 parts of film-forming aid, 1-2 parts of defoaming agent, 0.2-0.5 parts of leveling agent, and 5-15 parts of organic solvent; The modified acrylic resin is prepared by copolymerization of perfluorooctylethyl acrylate, methyl methacrylate, modified isocyanoethyl methacrylate and vinyl triethoxysilane, wherein the modified isocyanoethyl methacrylate is prepared by using salicylaldehyde and benzothiazole-2-carboxaldehyde to react with the amino groups at both ends of 1,5-naphthalenediamine to obtain a Schiff base monomer, and then DOPO and the Schiff base monomer undergo nucleophilic addition reaction and then graft with isocyanoethyl methacrylate; the modified hollow glass microspheres are prepared by using anhydrous ethanol as a solvent, n-butyl titanate as a titanium source, and glacial acetic acid as a chelating agent through a sol-gel method.

2. The lightweight radiation thermal insulation decorative panel for exterior walls according to claim 1 is characterized in that: The substrate is any one of an iron plate, a copper plate, a stainless steel plate, an aluminum plate, an asbestos-free fiber cement plate, an UHPC plate, a ceramic plate, and a clay plate.

3. The lightweight radiation thermal insulation decorative panel for exterior walls according to claim 1 is characterized in that: The film-forming aid is any one of propylene glycol methyl ether and ethylene glycol butyl ether; the defoamer is any one of fatty alcohol polyoxyethylene ether and alkylphenol polyoxyethylene ether; the leveling agent is sodium polyacrylate; and the organic solvent is acetone.

4. The exterior wall lightweight radiation thermal insulation decorative panel according to claim 1, characterized in that: The preparation method of the modified acrylate resin comprises the following steps: (1) salicylaldehyde, 1,5-naphthalenediamine and benzothiazole-2-carboxaldehyde are placed in a reactor, anhydrous ethanol solvent is added, the mixture is stirred evenly, glacial acetic acid is added dropwise, and the mixture is stirred at 65-80° C. for 4-5 hours. After the reaction is completed, the mixture is filtered, washed and dried to prepare a Schiff base monomer; (2) Putting a Schiff base monomer into a reactor, adding anhydrous ethanol solvent and DOPO, stirring and reacting at 75-85°C for 6-8 hours, filtering, washing and drying after the reaction is completed to prepare a DOPO derivative; (3) Put DOPO derivative, isocyanoethyl methacrylate and dibutyltin dilaurate in a reactor, add acetone solvent, raise the temperature to 45-50°C, stir and react for 10-12 hours, and after the reaction is completed, perform rotary evaporation, wash and dry to prepare modified isocyanoethyl methacrylate; (4) Perfluorooctyl ethyl acrylate, methyl methacrylate, modified isocyanoethyl methacrylate and vinyl triethoxysilane are placed in a reactor, acetone solvent is added and stirred evenly, nitrogen is passed through the reaction, azobisisobutyronitrile initiator is added, and the mixture is stirred and reacted at 55-70°C for 6-8 hours to prepare a modified acrylate resin.

5. The exterior wall lightweight radiation thermal insulation decorative panel according to claim 4, characterized in that: In the step (1), the molar ratio of salicylaldehyde, 1,5-naphthalenediamine and benzothiazole-2-carboxaldehyde is 1-1.2:1:1-1.

2.

6. The exterior wall lightweight radiation thermal insulation decorative panel according to claim 4, characterized in that: The molar ratio of the Schiff base monomer to DOPO in step (2) is 1:2-2.

3.

7. The exterior wall lightweight radiation thermal insulation decorative panel according to claim 4, characterized in that: In the step (3), the molar ratio of the DOPO derivative to isocyanoethyl methacrylate is 1:1-1.

2.

8. The exterior wall lightweight radiation thermal insulation decorative panel according to claim 4, characterized in that: In the step (4), the molar ratio of perfluorooctyl ethyl acrylate, methyl methacrylate, modified isocyanoethyl methacrylate and vinyl triethoxysilane is 2-6:2-6:1-2:

1.

9. The lightweight radiation thermal insulation decorative panel for exterior walls according to claim 1, characterized in that: The preparation method of the modified hollow glass microspheres comprises the following steps: taking anhydrous ethanol, tetrabutyl titanate and glacial acetic acid and mixing them uniformly to obtain a solution 1; taking anhydrous ethanol and deionized water and mixing them uniformly to obtain a solution 2; adding the solution 2 dropwise into the solution 1 under stirring, adjusting the pH value of the system to 3-4, stirring and reacting for 0.5-1h, then adding the hollow glass microspheres, continuing to stir for 1-1.5h, standing and aging for 10-12h and then drying, and calcining at 500-550°C for 3-4h to prepare the modified hollow glass microspheres.

10. A method for preparing a lightweight radiation thermal insulation decorative panel for an exterior wall according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1. Weigh each component by weight; S2, dispersing the modified acrylic resin in an organic solvent to obtain a dispersion, then adding the modified hollow glass microspheres, stirring evenly at 70-80° C., then heating to 100-120° C., stirring and reacting for 2-4 hours, to obtain a composite acrylic resin; S3, pouring the composite acrylic resin, silicon dioxide, heavy calcium carbonate, talcum powder, film-forming aid, defoaming agent and leveling agent into a mixer, stirring and mixing thoroughly to obtain a radiation cooling layer; S4. The radiation cooling layer is evenly coated on the surface of the substrate, and after thermal drying and curing, a lightweight radiation thermal insulation decorative panel for the exterior wall is prepared.

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