Modified thermal control coating filler with high ultraviolet reflectivity and low solar absorptivity and preparation method thereof

Abstract

The invention relates to a modified thermal control coating filler with high ultraviolet reflectivity and low solar absorptivity and a preparation method thereof. The modified thermal control coating filler with high ultraviolet reflectivity and low solar absorptivity comprises an ordered mesoporous silica molecular sieve carrier material SBA-15 and pigment ZrO2 particles loaded on the surface and / or in pores of the SBA-15, and the SBA-15 is in the shape of a hexagonal prism sheet.

Description

Technical Field

[0001] The invention belongs to the technical field of aerospace materials, and particularly relates to a coating filler of mesoporous molecular sieve SBA-15 modified zirconium dioxide with high ultraviolet reflectivity and low solar absorption ratio and a preparation method thereof. Background Art

[0002] The support system of a spacecraft is generally composed of a structural system, a thermal control system, a power system, an attitude and orbit control system, a life support system, and a return and landing system. The thermal control system of a spacecraft is an important support system for the overall operation of the spacecraft. Its importance is comparable to the body's temperature regulation system. The normal operation of the spacecraft is inseparable from the overall regulation of the thermal control system. The thermal control system is divided into active and passive control. As a passive control system, the thermal control coating reduces the solar absorption rate (α s ) and increase the hemispherical emissivity (ε H ), plays a key role in reducing heat accumulation on the spacecraft surface and enhancing infrared radiation heat dissipation. In addition, in order to maintain the thermal balance capability of thermal control coatings during service, they are also required to have high space durability.

[0003] White thermal control coating (abbreviated as white paint) is the most commonly used type of thermal control coating on the surfaces of satellites and spacecraft in various countries. It is composed of non-absorbing scattering particles as a filler and fixed with an adhesive. Thermal control coatings have a long history of development, and white paint thermal control coatings, as a product with excellent performance, have been studied in various aspects by researchers from various countries. Among the many white pigments, zirconium dioxide (ZrO2) is considered to be a potential thermal control coating substrate material due to its excellent high-temperature oxidation resistance, ultraviolet radiation tolerance and low absorption characteristics in the long-wave infrared band. For example, a Chinese patent with publication number CN117568736A discloses a method for preparing a thermal control coating with MgO-modified ZrO2 as a thermal control coating filler. This modification method is to dope Mg atoms into the zirconium oxide lattice, which increases the band gap of zirconium oxide to a certain extent. However, the optical performance of ZrO2 coatings within the solar spectrum is still insufficient, especially in the ultraviolet band, where it exhibits a low reflectivity (60%). This defect causes more ultraviolet light energy to be absorbed, which not only increases the surface temperature of the material but also accelerates the aging and degradation of the coating, thereby limiting its long-term stability. Summary of the Invention

[0004] In response to the above technical problems, the purpose of the present invention is to provide a modified thermal control coating filler with high ultraviolet reflectivity and low solar absorption ratio and a preparation method thereof. By regulating the addition ratio and microstructure of the modified material and the pigment, the optical and thermal properties of the filler are improved, aiming to meet the use requirements of spacecraft materials in the space environment.

[0005] In a first aspect, the present invention provides a modified thermal control coating filler with high ultraviolet reflectivity and low solar absorptivity, wherein the modified thermal control coating filler comprises: an ordered mesoporous silica molecular sieve carrier material SBA-15, and pigment ZrO2 particles loaded on the surface and / or in the pores of the SBA-15; The SBA-15 is in the shape of hexagonal thin sheets.

[0006] Preferably, the particle size of the SBA-15 is 500-700 nm, and the specific surface area is 600-700 m 2 / g; pore size is 5-10nm; The particle size of the ZrO2 particles is 3-10 nm.

[0007] Preferably, based on the total mass of the modified thermal control coating filler being 100%, the mass proportion of the SBA-15 is 50-95%, and the mass proportion of the ZrO2 particles is 5-50%.

[0008] In the second aspect, the present invention provides a direct mixing preparation method for the above-mentioned modified thermal control coating filler with high ultraviolet reflectivity and low solar absorption ratio. The direct mixing preparation method comprises the following steps: zirconium dioxide particles and mesoporous molecular sieve SBA-15 are fully and evenly mixed in a solvent, and then dried and subjected to a first heat treatment to obtain the modified thermal control coating filler with high ultraviolet reflectivity and low solar absorption ratio.

[0009] Preferably, in the direct mixing preparation method, the temperature of the first heat treatment is 400-600° C. and the time is 5-6 hours.

[0010] In a third aspect, the present invention provides a copolymerization preparation method for the above-mentioned modified thermal control coating filler with high ultraviolet reflectivity and low solar absorptivity. The copolymerization preparation method comprises the following steps: mixing a zirconium source with a surfactant P123 and an inorganic acid to form a micellar template solution, then adding a silicon source to form a precursor aqueous dispersion, and obtaining a solid product through a hydrothermal reaction; filtering, washing, drying, and heat-treating the solid product for a second time to obtain the modified thermal control coating filler with high ultraviolet reflectivity and low solar absorptivity.

[0011] Preferably, the zirconium source includes zirconium nitrate pentahydrate or zirconium oxychloride octahydrate; The silicon source includes TEOS; The block value of the surfactant P123 is EO:PO=2:7 or 3:7, preferably 2:7; The inorganic acid is a 2M-4M hydrochloric acid solution, preferably a 2M solution.

[0012] Preferably, the zirconium source is mixed with the surfactant P123 and the inorganic acid by stirring, the stirring temperature is 35-40° C., and the rotation speed is ≥400 and <500 rpm.

[0013] Preferably, in the precursor aqueous dispersion, the molar ratio of the triblock nonionic surfactant P123, the silica precursor TEOS, the Zr precursor, the inorganic acid HCl, and deionized water is 0.017:1:(0.02-0.1):5.7:194.

[0014] Preferably, the hydrothermal reaction process comprises: heating from room temperature to 90-100°C at a heating rate of 5-10°C / min and keeping the temperature for 20-24 hours; The second heat treatment is carried out in an air atmosphere, heating from room temperature to 400-600° C. at a heating rate of 2 K / min and keeping the temperature for 5-6 hours.

[0015] Beneficial effects (1) The thermal control coating modified filler provided by the present invention has an ordered hexagonal lamellae and a uniform anchoring position, so it has excellent optical properties. Unlike the existing dense inorganic zirconium oxide coatings that are easy to peel and crack, the filler material has a high specific surface area, adjustable pore size (5-10nm) and excellent thermal stability of the molecular sieve, so its service stability is improved to a certain extent. Moreover, there is a strong interaction between zirconium and oxygen and silicon and oxygen as a connection method inside the filler, which greatly improves the interface stability and makes the bonding strength between the fillers higher. The molecular sieve material itself is light in weight. When used as a filler, it can be mixed with a binder at a low pigment ratio, making the coating lighter and having better mechanical properties. (2) The raw materials and preparation price of the coating are low, the equipment requirements are low, the process is simple and the operation is convenient; commercially available metal salts (such as zirconium nitrate pentahydrate) and organic silicon sources (such as tetraethyl orthosilicate) are used as raw materials, and the types of raw materials are wide to choose from and the price is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic structural diagram of the modified thermal control coating filler with high ultraviolet reflectivity and low solar absorptivity provided by the present invention; Figure 2 This is an SEM photograph of the micro-nanostructure of the thermal control coating filler with high UV reflectivity and low solar absorptivity in Example 1; Figure 3 A is a TEM photo of the thermal control coating filler with high UV reflectivity and low solar absorption ratio in Example 1. Figure 3 B is a low-magnification TEM photograph of the thermal control coating filler with high UV reflectivity and low solar absorptivity in Example 1; Figure 4This is a BET diagram of the solid powder of the modified thermal control coating filler precursor dispersion in Example 1 after filtration, washing, drying, and heat treatment; Figure 5 This is a SEM photo of the modified thermal control coating filler in Example 2; Figure 6 This is a SEM photo of the modified thermal control coating filler in Example 6; Figure 7 This is the SEM of the modified thermal control coating filler in Example 9 with a molar ratio of metal salt to silicon source of 0.5:1; Figure 8 The high-angle XRD spectra of the modified thermal control coating fillers with different molar ratios of metal salt to silicon source in Examples 8 and 9; Figure 9 A is the solar spectrum reflectance graph of the modified thermal control coating filler in Examples 8 and 9 with a molar ratio of metal salt to silicon source of (0.02-0.1):1, Figure 9 B is a solar spectrum reflectance graph of the modified thermal control coating filler in Examples 8 and 9 with a molar ratio of metal salt to silicon source of (0.1-0.4):1; Figure 10 This is the emissivity spectrum of the modified thermal control coating filler in Examples 8 and 9 with a molar ratio of metal salt to silicon source of (0.04-1.0):1. DETAILED DESCRIPTION

[0017] The present invention is further described below through the following embodiments. It should be understood that the following embodiments are only used to illustrate the present invention, rather than to limit the present invention.

[0018] First, if Figure 1 As shown, the present invention provides a modified thermal control coating filler with high ultraviolet reflectivity and low solar absorptivity. The modified thermal control coating filler may include: an ordered mesoporous silica molecular sieve carrier material SBA-15, and pigment ZrO2 particles supported on the surface and / or within the pores of the SBA-15.

[0019] In some embodiments, the filler can be composed of two or three layers depending on the preparation conditions (e.g., loading amount, aging time). Preferably, the pigment and the modified layer form a heterogeneous interface, forming Zr-O and Si-O bonds, which have high bonding strength.

[0020] In some embodiments, the SBA-15 may be in the form of hexagonal flakes; preferably, the particle size may be 500-700 nm, and the specific surface area may be 600-700 m 2 / g; the pore size can be 5-10nm. If the specific surface area is too small, light scattering will be reduced and the reflectivity will be lowered; at the same time, if the pore size is too small, there will be no place for the zirconium oxide to be loaded, thus reducing the loading rate.

[0021] In some embodiments, the ZrO2 particles may have a particle size of 3-10 nm. If the particle size is too large, the particles may agglomerate, grow on the surface of the molecular sieve, and destroy the ordered structure.

[0022] In some embodiments, based on the total mass of the modified thermal control coating filler being 100%, the SBA-15 may comprise 50-95% by mass, and the ZrO2 particles may comprise 5-50% by mass. Excessive SBA-15 content can produce more surface hydroxyl groups, creating absorption peaks and lowering optical reflectivity. Excessive ZrO2 content can affect the overall UV reflectivity of the pigment due to its inherently low UV reflectivity.

[0023] In some embodiments, the reflectivity of the modified thermal control coating filler in the ultraviolet band of 200-380nm is increased by more than 40% compared with pure zirconium oxide pigment, and the ultraviolet reflectivity can be ≥92%; the reflectivity in the visible light band can be ≥90%, and the solar absorption ratio can be 0.03-0.08, preferably 0.03-0.05.

[0024] In some embodiments, the specific surface area of the modified thermal control coating filler may be 500-820 m 2 / g, the pore volume can be 0.5-1.3cm 3 / g.

[0025] It should be noted that in the technical solution disclosed in the present invention, SBA-15 is an ordered mesoporous silica material with a high specific surface area, adjustable pore size (5-10nm) and excellent catalytic properties and thermal stability. By loading ZrO2 particles on the surface or in the pores of SBA-15, the dispersion of active sites can be significantly improved and the high-temperature agglomeration of ZrO2 can be inhibited; at the same time, due to its ordered silica pore structure and excellent stability, the loadable sites can be increased, stronger metal oxide chemical bonds can be formed, the possibility of light scattering can be increased, and the optical properties and spatial stability of the filler can be significantly improved.

[0026] In addition, it should be noted that single zirconia materials have problems such as low specific surface area, volume expansion caused by high-temperature phase transition, and low reflectivity in the ultraviolet band. By utilizing the ordered silica channels of the molecular sieve and the high reflectivity in the ultraviolet band, adding an appropriate amount of SBA-15 can increase the band gap of zirconia while reducing the free carrier density, thereby reducing the solar absorption ratio and improving the reflectivity of the pigment in the ultraviolet and visible light bands. At the same time, the molecular sieve material itself is light in weight. When used as a pigment, it can be mixed with a binder at a low pigment ratio, making the coating lighter and having better mechanical properties. The coating filler provided by the present invention improves the bonding performance of the modified material and the pigment matrix through the strong bonding mode of zirconium and oxygen and silicon and oxygen, and has excellent optical and mechanical properties. At the same time, the modified filler has the characteristic of replaceable pigment types, which can meet the functional requirements of the thermal control coating such as anti-ultraviolet radiation and anti-static, and its raw materials and preparation are inexpensive and easy to implement and operate. It can be widely used in low-orbit spacecraft using thermal control coatings in the aerospace field.

[0027] The following is an illustrative example of a method for preparing the modified thermal control coating filler having high ultraviolet reflectivity and low solar absorptivity by direct mixing.

[0028] Among them, the direct mixing preparation method can include the following steps: fully and evenly mixing zirconium dioxide particles and mesoporous molecular sieve SBA-15 in a solvent, and then drying and performing a first heat treatment to obtain the modified thermal control coating filler with high ultraviolet reflectivity and low solar absorption ratio.

[0029] In some embodiments, the method for preparing the mesoporous molecular sieve SBA-15 may include the following steps: (1) dissolving polyethylene glycol-block-polypropylene glycol-block-polyethylene glycol triblock copolymer nonionic surfactant P123 and inorganic acid in deionized water to obtain a micelle template solution; (2) adding tetraethyl orthosilicate (TEOS) dropwise to the micelle template solution to obtain a preliminary reaction solution, and then allowing the solution to stand or stir to promote full combination of the silicon source and the template to obtain a precursor dispersion solution; (3) subjecting the precursor dispersion to a hydrothermal reaction to obtain a solid product, which is filtered, washed, dried, and calcined to remove the template to obtain the mesoporous molecular sieve SBA-15.

[0030] In step (1), the block value of the surfactant P123 can be EO:PO=2:7 or 3:7, preferably 2:7; the inorganic acid can be a 2M-4M hydrochloric acid solution prepared from 36-38% concentrated HCl, preferably 2M.

[0031] In step (1), the surfactant P123 and the inorganic acid are dissolved in deionized water under stirring; the stirring speed can be ≥400 and <500 rpm, preferably 400 rpm; the reaction temperature can be 35-40°C, preferably 35°C; and the hydrolysis time can be 10-14h, preferably 12h.

[0032] In step (2), in the preliminary reaction liquid, the molar ratio of surfactant P123, silica precursor TEOS, inorganic acid HCl, and deionized water can be controlled to be 0.017:1:5-8:190-220, preferably 0.017:1:5.7:194.

[0033] In step (2), after the tetraethyl orthosilicate (TEOS) is added dropwise to the micelle template solution, stirring can be performed to form a preliminary reaction solution; the stirring speed can be 400-500 rpm, and the stirring time can be 1-5 minutes, preferably 3-5 minutes, and more preferably 5 minutes. Stirring for too long can result in the formation of fibers, resulting in an incomplete structure.

[0034] Wherein, in step (2), the temperature of the preliminary reaction solution during standing or stirring can be 35-40° C., and the time can be 20-30 hours, preferably 24 hours.

[0035] Wherein, in step (3), the process of the hydrothermal reaction may include: placing the precursor dispersion in a 100-300 mL (e.g., 300 mL) hydrothermal reactor containing a PTFE liner, heating the reactor from room temperature to 90-100 ° C (e.g., 100 ° C) at a heating rate of 5-10 ° C / min (e.g., 5 ° C / min) and keeping the temperature for 20-24 (e.g., 24 hours), taking out the hydrothermal reactor and air cooling it.

[0036] Wherein, in step (3), the washing solvent can be deionized water and anhydrous ethanol; the drying temperature can be 60-80° C. (such as 80° C.), and the drying time can be 10-20 h.

[0037] In step (3), the calcination treatment can be carried out in an air atmosphere at a temperature of 400-600°C for 3-10 hours. Preferably, the dried molecular sieve powder is placed in an air atmosphere and heated from room temperature to 550°C at a heating rate of 2K / min, and kept at this temperature for 6 hours. Too high a temperature can easily induce a phase transition to produce zirconium silicate, while too low a temperature cannot completely remove the surfactant.

[0038] In some embodiments, in the direct mixing preparation method, the mass ratio of the zirconium dioxide particles to the mesoporous molecular sieve SBA-15 can be (0.02-1):1, preferably 0.05:1. By controlling the ratio of the two within an appropriate range, the reflectivity in the ultraviolet band can be significantly improved while having a low solar absorption ratio.

[0039] In some embodiments, in the direct mixing preparation method, the zirconium dioxide particles and the mesoporous molecular sieve SBA-15 are mixed and then dried at a temperature of 60-80° C. (eg, 80° C.) for 10-12 hours.

[0040] In some embodiments, in the direct mixing preparation method, the temperature of the first heat treatment can be 400-600° C. and the time can be 5-6 hours. The optical properties and thermal stability of the modified filler can be enhanced by heat treatment.

[0041] The following is an illustrative example of a copolymerization method for preparing the modified thermal control coating filler having high ultraviolet reflectivity and low solar absorptivity.

[0042] Among them, the copolymerization preparation method may include the following steps: mixing a zirconium source with a surfactant P123 and an inorganic acid to form a micelle template solution, then adding a silicon source to form a precursor aqueous dispersion, and obtaining a solid product through a hydrothermal reaction; filtering, washing, drying, and heat-treating the solid product for a second time to obtain the modified thermal control coating filler with high ultraviolet reflectivity and low solar absorption ratio.

[0043] In some embodiments, the zirconium source may include zirconium nitrate pentahydrate or zirconium oxychloride octahydrate. Zirconium dioxide prepared from zirconium nitrate pentahydrate has a relatively higher reflectivity in the ultraviolet band, while zirconium dioxide prepared from zirconium oxychloride octahydrate has relatively better thermal stability.

[0044] In some embodiments, the block value of the surfactant P123 may be EO:PO=2:7 or 3:7, preferably 2:7; the inorganic acid may be a 2M-4M hydrochloric acid solution prepared from 36-38% concentrated HCl, preferably 2M.

[0045] In some embodiments, the zirconium source is mixed with the surfactant P123 and the inorganic acid by stirring. The stirring temperature is 35-40° C. and the rotation speed can be ≥400 and <500 rpm.

[0046] In some embodiments, the silicon source may include TEOS; after adding the silicon source, stirring may be continued for 1-5 minutes, and then allowed to stand for 20-24 hours to obtain a precursor aqueous dispersion.

[0047] In some embodiments, in the precursor aqueous dispersion, the molar ratio of the triblock nonionic surfactant P123, the silica precursor TEOS, the Zr precursor, the inorganic acid HCl, and deionized water can be 0.017:1:(0.02-0.1):5.7:194. Furthermore, when the molar ratio of the Zr precursor is in the range of 0.02-0.1, as a low loading, the reflectivity of the filler in the ultraviolet band is significantly improved, while the reflectivity in the visible light band remains at a high level; when the molar ratio of the Zr precursor is in the range of 0.5-1.0, the improvement of the filler in the ultraviolet band decreases. At the same time, because a large amount of ZrO2 is attached to the surface in the form of clusters, the structural order of the molecular sieve material itself is reduced, resulting in a decrease in the reflectivity in the visible light band.

[0048] In some embodiments, the hydrothermal reaction process may include: heating from room temperature to 90-100° C. at a heating rate of 5-10° C. / min (eg, 8.5° C. / min) and keeping the temperature for 20-24 hours, removing the hydrothermal reactor and air cooling.

[0049] In some embodiments, the second heat treatment can be performed in an air atmosphere, heating from room temperature to 400-600° C. (eg, 550° C.) at a heating rate of 2 K / min and maintaining the temperature for 5-6 hours (eg, 6 hours).

[0050] The present invention introduces Zr source into the mesoporous channels of SBA-15 in a particle or amorphous state through a copolymerization method, forming a composite structure of "molecular sieve channel confined ZrO2". At low doping, it avoids the agglomeration problem of traditional mechanical mixing and maintains the ordered hexagonal structure of the molecular sieve.

[0051] Traditional physical mixing or impregnation methods generally struggle to achieve uniform dispersion of ZrO2 within the pores of SBA-15, easily leading to surface accumulation or pore blockage, which can degrade pigment performance. Furthermore, some Zr precursors can strongly interact with the silanol groups of SBA-15, leading to pore blockage during the sol-gel process and disrupting the mesoporous structure of SBA-15. The present invention overcomes these technical difficulties by employing a copolymerization method and modifying the resting time and resting conditions after adding the silicon source, optimizing parameters such as the stirring rate and time during the hydrolysis of the Zr precursor, and optimizing the Zr source addition ratio.

[0052] In summary, the present invention allows for the microstructure of SBA-15 to be tuned by adjusting the preparation steps, achieving optimal structural stability and reflectivity. This is combined with zirconium dioxide, which exhibits excellent high-temperature oxidation resistance, UV radiation tolerance, chemical inertness, high mechanical strength, and unique electronic properties. By anchoring ZrO2 particles within the SBA-15 framework or pores, the coating achieves high stability and excellent optical properties.

[0053] Furthermore, by adjusting the type of metal salt, the surfactant block value, and the conditions of the precursor dissolution reaction, the dispersion of the silicon source and the uniformity of the molecular sieve structure were greatly improved, resulting in a pure white pigment with a uniform texture and no noticeable agglomeration. Combined with a composite modification method, the zirconium oxide is anchored within the molecular sieve pores or framework. Through the strong bonding between the zirconium and silicon oxides, the pigment's adhesion and stability are significantly enhanced.

[0054] The following examples are further given to illustrate the present invention in detail. It should be understood that the following examples are only used to further illustrate the present invention and cannot be interpreted as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above content of the present invention all fall within the scope of protection of the present invention. The specific process parameters and the like in the following examples are only examples within a suitable range, and those skilled in the art can make selections within a suitable range through the description herein, and are not limited to the specific numerical values exemplified below. Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art.

[0055] Test method: Scanning electron microscopy was used to observe the surface morphology of the sample; transmission electron microscopy was used to observe the pore structure of the sample; BET method was used to test the specific surface area of the filler; X-ray diffraction method was used to test the crystal form of the sample; UV-visible spectrophotometer was used to test the optical properties of the coating filler; EDS spectrum was used to observe the element content on the sample surface.

[0056] Example 1

[0057] The preparation method of SBA-15 and the modified thermal control coating filler with high ultraviolet reflectivity and low solar absorptivity provided in this embodiment may include the following steps: (1) Preparation of mesoporous molecular sieve SBA-15 dispersion: 4 g of surfactant P123 was dissolved in 150 ml of a mixture of 2 M HCl and deionized water, and stirred at 400 rpm in a 35°C water bath or oil bath for 12 hours to form a micellar template solution; 8.5 g of TEOS was then slowly added dropwise to the micellar template solution, stirred for 5 minutes, and then allowed to stand for 24 hours to obtain a precursor dispersion; the resulting white colloidal reactant was placed in a 300 ml hydrothermal reactor containing a PTFE liner and subjected to hydrothermal reaction at 100°C for 24 hours to obtain a well-dispersed molecular sieve suspension; (2) Preparation of modified thermal control coating filler precursor dispersion: The above molecular sieve dispersion preparation experiment was repeated with surfactant P123, TEOS, zirconium oxychloride octahydrate, HCl and deionized water at a molar ratio of 0.017:1:0.05:5.7:194; the obtained white colloidal reactant was placed in a 300 ml hydrothermal reactor containing PTFE lining and hydrothermally reacted at 90-100 ° C for 24 h to obtain a well-dispersed precursor suspension; (3) The suspension obtained in steps (1) and (2) was transferred to a suction filtration device, and was repeatedly washed with deionized water and anhydrous ethanol to remove the residual surfactant, and then placed in an 80°C oven for drying overnight; then placed in an air atmosphere and heated to 550°C at a rate of 2K / min for 6 hours to obtain the optimized process SBA-15 and modified thermal control coating filler, respectively.

[0058] In the above-mentioned Example 1, the specific surface areas of the filler and SBA-15 tested by BET were 819.87 and 646.41 m 2 / g; EDS energy spectrum shows that the zirconium content on the sample surface is 1at%; XRD spectrum shows that the sample is still amorphous; the optical performance is compared with pure zirconium oxide in the ultraviolet band of 200-380nm, with a reflectivity of more than 90% in the visible light band, and a solar absorption ratio of 0.048.

[0059] Example 2

[0060] The preparation process of the modified thermal control coating filler in this Example 2 refers to that in Example 1, with the only difference being that in step (2), the temperature of the water bath or oil bath is 45°C.

[0061] In this embodiment, the structure of the coating filler becomes rod-shaped, the reflectivity of the molecular sieve in the ultraviolet band is reduced, and the solar absorption ratio is 0.16.

[0062] Example 3

[0063] The preparation process of the modified thermal control coating filler in this Example 3 refers to that in Example 1, with the only difference being that in step (2), the temperature of the water bath or oil bath is 55°C.

[0064] In this embodiment, the coating filler structure becomes fibrous and has poor stability.

[0065] Example 4

[0066] The preparation process of the modified thermal control coating filler in this Example 4 refers to that in Example 1, with the only difference being that in step (2), the rotation speed is 500 rpm.

[0067] In this embodiment, a spherical mixed phase appears in the microstructure of the coating filler.

[0068] Example 5

[0069] The preparation process of the modified thermal control coating filler in this Example 5 refers to that in Example 1, with the only difference being that in step (2), the temperature of the water bath or oil bath is 45° C., and the rotation speed is 500 rpm.

[0070] In this embodiment, the microstructure of the coating filler is rod-shaped, flake-shaped, and spherical, and the structure is non-uniform.

[0071] Example 6

[0072] The preparation process of the modified thermal control coating filler in this Example 6 refers to that in Example 1, with the only difference being that in step (2), the temperature of the water bath or oil bath is 55° C., and the rotation speed is 500 rpm.

[0073] In this embodiment, the microstructure of the coating filler is in the shape of fiber rods.

[0074] Example 7

[0075] The preparation process of the modified thermal control coating filler in Example 7 refers to that in Example 1, with the only difference being that in step (2), stirring is continued for 5 minutes after adding TEOS and then for 24 hours.

[0076] In this embodiment, at stirring speeds of 400 rpm and 500 rpm, agglomeration of the filler structure occurred.

[0077] Example 8

[0078] The preparation process of the modified thermal control coating filler in Example 8 refers to that in Example 1, with the only difference being that in step (2), the molar ratio of the metal salt to the silicon source is 0.02-0.1:1.

[0079] In this embodiment, when the molar ratio of the metal salt to the silicon source is 0.02:1, the solar absorption ratio is a maximum of 0.08. As the amount of metal salt added increases, the solar absorption ratio shows a trend of first decreasing and then increasing. It reaches the minimum value when the molar ratio of the metal salt to the silicon source is 0.05:1, and the reflectivity is negatively correlated with the amount added.

[0080] Example 9

[0081] The preparation process of the modified thermal control coating filler in this Example 9 refers to that in Example 1, with the only difference being that in step (2), the molar ratio of the metal salt to the silicon source is 0.1-1:1.

[0082] In this embodiment, with the addition of metal salt, the solar absorption ratio gradually increases and the reflectivity gradually decreases; XRD results show that with the increase of metal salt, the peak of SBA-15 gradually weakens and the peak intensity of zirconium oxide increases. Zirconium oxide is not only incorporated into the gaps of SBA-15, but also grows on the outer surface, blocking the pores.

[0083] Example 10

[0084] The preparation process of the modified thermal control coating filler in this Example 10 refers to that in Example 1, with the only difference being that in step (2), the metal salt is zirconium nitrate pentahydrate.

[0085] In this embodiment, the filler structure still maintains a uniform hexagonal prism flake shape; the solar absorption ratio is minimum 0.048 when the molar ratio of metal salt to silicon source is 0.05:1; the specific surface area of the coating filler is negatively correlated with the amount of metal salt added.

[0086] Table 1 shows the reaction conditions and performance parameters of the modified thermal control coating fillers prepared in Examples 1-10 of the present invention:

[0087] Figure 2 This is a SEM image of the micro-nanostructure of the thermal control coating filler with high UV reflectivity and low solar absorptivity in Example 1, at a magnification of 6.3k. As can be seen from the image, the micro-nanostructure of the filler after molding is composed of hexagonal prism flakes.

[0088] Figure 3 A is a TEM photograph of the thermal control coating filler with high UV reflectivity and low solar absorptivity in Example 1. The figure shows that the filler's micro-nanostructure is a mesoporous molecular sieve composed of uniform hexagonal pores, and zirconium oxide is well dispersed in the molecular sieve framework. Figure 3 B is a low-magnification TEM photograph of the thermal control coating filler with high ultraviolet reflectivity and low solar absorption ratio in Example 1. It can be seen from the figure that the micro-nano structure of the filler is a uniform hexagonal prism flake.

[0089] Figure 4 This is the BET diagram of the solid powder of the modified thermal control coating filler precursor dispersion after filtration, washing, drying and heat treatment in Example 1. It can be seen from the figure that the specific surface area of the modified filler is 819.87m 2 / g, pore volume 1.065cm 3 / g, and the pore size is 5.20nm.

[0090] Figure 5 This is a SEM photograph of the modified thermal control coating filler in Example 2, with a magnification of 12k. As can be seen from the figure, the micro-nano structure of the filler after molding is composed of rod-like structures.

[0091] Figure 6 This is a SEM photograph of the modified thermal control coating filler in Example 6, with a magnification of 1.2k. As can be seen from the figure, the micro-nano structure of the filler after molding is composed of a fibrous structure.

[0092] Figure 7 This is a SEM image of the modified thermal control coating filler in Example 9, with a metal salt to silicon source molar ratio of 0.5:1, at a magnification of 0.5k. As can be seen from the image, the filler's micro-nanostructure agglomerates after molding, resulting in a decrease in structural uniformity.

[0093] Figure 8 The following are high-angle XRD spectra of the modified thermal control coating fillers at different metal salt to silicon source molar ratios in Examples 8 and 9. As can be seen from the figure, no peak corresponding to zirconium oxide is observed in samples with a zirconium oxide content of 0.04-0.6, indicating that zirconium oxide is well dispersed and primarily located within the SBA-15 framework. A distinct peak corresponding to zirconium oxide appears at a zirconium oxide content of 1.0, indicating that zirconium oxide grows not only within the framework but also within the pores.

[0094] Figure 9 A is a solar spectrum reflectance graph of the modified thermal control coating filler in Examples 8 and 9 with a molar ratio of metal salt to silicon source of (0.02-0.1):1. As can be seen from the graph, the reflectance in the ultraviolet band is significantly improved before and after doping, and there is a clear absorption peak in the infrared band due to the presence of surface hydroxyl groups; Figure 9 B is the solar spectrum reflectance graph of the modified thermal control coating filler in Examples 8 and 9 with a molar ratio of metal salt to silicon source of (0.1-0.4):1. It can be seen from the graph that the reflectance gradually decreases with the increase of the molar ratio of metal salt to silicon source.

[0095] Figure 10 This is the emissivity spectrum of the modified thermal control coating filler with a metal salt to silicon source molar ratio of (0.04-1.0):1 in Examples 8 and 9. As can be seen from the figure, the emissivity of the modified thermal control coating filler is significantly improved compared to pure zirconia.

[0096] Although the present invention has been described in detail through the above preferred embodiments, it should be understood that the above description is not intended to limit the present invention. After reading the above description, various modifications and substitutions of the present invention will become apparent to those skilled in the art. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A modified thermal control coating filler with high ultraviolet reflectivity and low solar absorption ratio, characterized in that: The modified thermal control coating filler comprises: ordered mesoporous silica molecular sieve carrier material SBA-15, and pigment ZrO2 particles loaded on the surface and / or in the pores of the SBA-15; The SBA-15 is in the shape of hexagonal thin sheets.

2. The modified thermal control coating filler according to claim 1, characterized in that: The particle size of SBA-15 is 500-700nm and the specific surface area is 600-700m 2 / g; pore size is 5-10nm; The particle size of the ZrO2 particles is 3-10 nm.

3. The modified thermal control coating filler according to claim 1 or 2, characterized in that: Taking the total mass of the modified thermal control coating filler as 100%, the mass of the SBA-15 accounts for 50-95%, and the mass of the ZrO2 particles accounts for 5-50%.

4. A method for directly mixing and preparing a modified thermal control coating filler with high ultraviolet reflectivity and low solar absorption ratio according to any one of claims 1 to 3, characterized in that: The direct mixing preparation method comprises the following steps: fully and evenly mixing zirconium dioxide particles and mesoporous molecular sieve SBA-15 in a solvent, and then drying and performing a first heat treatment to obtain the modified thermal control coating filler with high ultraviolet reflectivity and low solar absorption ratio.

5. The preparation method according to claim 4, characterized in that In the direct mixing preparation method, the temperature of the first heat treatment is 400-600° C. and the time is 5-6 hours.

6. A copolymerization method for preparing a modified thermal control coating filler with high ultraviolet reflectivity and low solar absorptivity according to any one of claims 1 to 3, characterized in that: The copolymerization preparation method comprises the following steps: mixing a zirconium source with a surfactant P123 and an inorganic acid to form a micelle template solution, then adding a silicon source to form a precursor aqueous dispersion, and obtaining a solid product through a hydrothermal reaction; filtering, washing, drying, and subjecting the solid product to a second heat treatment to obtain the modified thermal control coating filler with high ultraviolet reflectivity and low solar absorptivity.

7. The preparation method according to claim 6, characterized in that The zirconium source includes zirconium nitrate pentahydrate and zirconium oxychloride octahydrate; The silicon source includes TEOS; The block value of the surfactant P123 is EO:PO=2:7 or 3:7, preferably 2:7; The inorganic acid is a 2M-4M hydrochloric acid solution, preferably a 2M solution.

8. The preparation method according to claim 7, characterized in that The zirconium source is mixed with the surfactant P123 and the inorganic acid by stirring. The stirring temperature is 35-40° C. and the rotation speed is ≥400 and <500 rpm.

9. The preparation method according to claim 6 or 7, characterized in that: In the precursor aqueous dispersion, the molar ratio of triblock nonionic surfactant P123, silica precursor TEOS, Zr precursor, inorganic acid HCl, and deionized water is 0.017:1:(0.02-0.1):5.7:

194.

10. The preparation method according to any one of claims 6 to 8, characterized in that The hydrothermal reaction process includes: heating from room temperature to 90-100°C at a heating rate of 5-10°C / min and keeping the temperature for 20-24 hours; The second heat treatment is carried out in an air atmosphere, heating from room temperature to 400-600° C. at a heating rate of 2 K / min and keeping the temperature for 5-6 hours.

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