A superhydrophobic transparent thermal insulating film containing rubidium tungsten bronze, its preparation method and application

Abstract

This invention belongs to the field of transparent glass heat-insulating films and coatings, and particularly relates to a superhydrophobic transparent heat-insulating film containing rubidium tungsten bronze, its preparation method, and its application. The superhydrophobic transparent heat-insulating film comprises a heat-insulating layer and a hydrophobic layer. The heat-insulating layer contains tungsten bronze nanoparticles, and the hydrophobic layer is attached to the heat-insulating layer. The chemical formula of the rubidium tungsten bronze is: Rb 0.27 WO3. Its preparation method includes first preparing a heat-insulating layer film, and then constructing a hydrophobic film on the heat-insulating layer film using a multilayer assembly method. The film developed and prepared by this invention has excellent visible light transmittance, near-infrared shielding performance, and superhydrophobic properties. This film can be widely used in architectural glass and automotive windows, effectively reducing indoor temperature, achieving energy conservation and emission reduction, and also has self-cleaning and anti-fouling functions. This invention has a reasonable structural design, a simple and controllable preparation process, and the resulting product has superior performance, facilitating large-scale industrial application.

Description

Technical Field

[0001] This invention belongs to the field of transparent glass heat-insulating films and coatings, and in particular designs a superhydrophobic transparent heat-insulating film / coating with rubidium tungsten bronze nanoparticles as functional fillers, its preparation method and application. Background Technology

[0002] With the continuous development of industrialization and urbanization in my country, the demand for energy-saving and heat-insulating glass films or coatings is increasing. At the same time, cleaning building glass curtain walls requires significant manpower and resources, especially for high-rise buildings where high-altitude work is necessary and carries inherent risks. Therefore, self-cleaning superhydrophobic films / coatings can solve this problem.

[0003] Commonly used functional inorganic fillers for transparent heat-insulating films include indium-doped tin oxide (ITO), antimony-doped tin oxide (ATO), nano-gold (n-Au), nano-silver (n-Ag), and nano-lanthanum hexaboride (LaB6). Among these, ITO and ATO exhibit poor shielding performance in the 760–1400 nm range, and indium metal has high raw material costs. LaB6 also has poor shielding performance in the 1400–2500 nm range, and its preparation cost is high. The application of n-Au and n-Ag films involves complex glass film preparation processes (vacuum anti-oxidation measures) and expensive raw material prices. Rubidium-tungsten bronze, like cesium-tungsten bronze, has good visible light transmittance and excellent near-infrared shielding performance across the entire wavelength range. Using rubidium-tungsten bronze nanoparticles as inorganic fillers to prepare heat-insulating coatings or films can be widely applied to building glass curtain walls and automotive windows to achieve energy-saving effects. Furthermore, rubidium tungsten bronze nanopowder is deep blue, and its film or coating is also blue, which not only has a certain light transmittance but also has an aesthetic effect.

[0004] In the prior art, some researchers have attempted to use tungsten bronze to prepare superhydrophobic transparent heat-insulating coatings; for example, patent CN113185871A describes "A Tungsten Bronze-Based Superhydrophobic Transparent Heat-Insulating Coating and Its Preparation Method." This patent describes a tungsten bronze-based superhydrophobic transparent heat-insulating coating, which is obtained by dissolving hydrophobically modified nano-tungsten bronze and hydrophobically modified powder in an organic solvent in a resin solution for film formation; the hydrophobically modified nano-tungsten bronze is prepared by adding nano-tungsten bronze to n-hexane solvent, stirring evenly at room temperature to obtain a uniformly dispersed mixture, and then... The hydrophobic modified powder is obtained by adding a hydrophobic modifier, stirring, washing, centrifuging, and drying. The hydrophobic modified powder is obtained by adding nanoparticles to anhydrous ethanol solvent, stirring at room temperature to obtain a uniformly dispersed mixed solution, then adding a silane coupling agent hydrolysate and a hydrophobic modifier, stirring at 60–90°C, and washing, centrifuging, and drying. The hydrophobic modifier used in the preparation of the hydrophobic modified nano-tungsten bronze and the hydrophobic modified powder is one or more of trimethylchlorosilane, perfluorodecyltriethoxysilane, hexamethyldisilazane, and dodecyltrimethoxysilane. This patent does not involve a multilayer structure design, and its effect needs further enhancement. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides for the first time a superhydrophobic transparent heat-insulating film with a multilayer structure containing rubidium tungsten bronze, along with its preparation method and applications.

[0006] The present invention discloses a superhydrophobic transparent heat-insulating film containing rubidium tungsten bronze, which comprises a heat-insulating layer and a hydrophobic layer. The heat-insulating layer contains tungsten bronze nanoparticles, and the hydrophobic layer is attached to the heat-insulating layer.

[0007] Preferably, this invention provides a superhydrophobic transparent thermal insulation film containing rubidium tungsten bronze, wherein the particle size of the rubidium tungsten bronze nanoparticles used in the thermal insulation layer is 20–500 nm, preferably 50–300 nm. In this invention, excessively large particle sizes of the rubidium tungsten bronze powder will lead to a decrease in the visible light transmittance of the film, while excessively small particle sizes will result in high costs and difficulty in dispersion. Furthermore, excessively small tungsten bronze nanoparticles typically have poor near-infrared shielding performance, leading to a deterioration in the thermal insulation effect of the film. In this invention, the chemical formula of rubidium tungsten bronze is: Rb 0.27 WO3.

[0008] The rubidium-tungsten bronze powder used in this invention is prepared by a solvothermal method. The specific steps are as follows: First, 2 mmol of sodium tungstate dihydrate is weighed and dissolved in 60 ml of deionized water. Then, 3 mmol of citric acid and 10 mmol of glucose are added to the solution sequentially, and the mixture is stirred for 10 min to ensure complete dissolution (for industrial applications, this can be scaled up proportionally). Next, a certain amount of hydrochloric acid is rapidly added to the above solution. The solution turns yellow and forms a yellow gel. After stirring for another 30 min, the solution is poured into a 100 ml hydrothermal reactor liner for hydrothermal reaction. The hydrothermal holding temperature is 120℃, and the hydrothermal time is 7 h. After the hydrothermal reaction, the obtained precipitate is washed by centrifugation with deionized water and alcohol, and then vacuum dried at 60℃ for 8 h to finally obtain yellow-green tungsten trioxide hydrate (WO3·H2O) powder. Then, an appropriate amount of the precursor powder is weighed and placed in 50 ml of anhydrous ethanol, and ultrasonically dispersed for 30 min to form a uniformly dispersed suspension. Finally, a certain amount of RbCl is weighed and dissolved in 13 ml of acetic acid. The acetic acid solution was then poured into an ethanol dispersion containing the precursor, stirred thoroughly, and then poured into a 100 ml hydrothermal reactor liner for hydrothermal reaction. The hydrothermal temperature was 220℃, and the hydrothermal time was 24 h. After the hydrothermal reaction, the obtained blue precipitate was washed (twice with deionized water and alcohol), centrifuged, filtered, and vacuum dried to finally obtain blue Rb. 0.27 WO3 powder.

[0009] As a further preferred option, the thickness of the heat insulation layer is greater than the particle size of the rubidium tungsten bronze nanoparticles used, typically 0.5–10 micrometers, preferably 1–2 micrometers. Too thick a layer will result in uneven distribution of powder particles in the film, thus affecting the uniformity of the film's color; too thin a layer will affect the physical properties of the film, making the heat insulation layer easily damaged.

[0010] Preferably, this invention provides a superhydrophobic transparent thermal insulation film containing rubidium tungsten bronze. The hydrophobic film is constructed by multi-layer assembly, with a hydrophobic organic film attached to the thermal insulation layer, and then a hydrophobic inorganic material, including silicon dioxide, is sprayed onto the organic film. The hydrophobic inorganic material further enhances the hydrophobic properties.

[0011] As a preferred embodiment, the present invention provides a superhydrophobic transparent heat-insulating film containing rubidium tungsten bronze, wherein the thickness of the organic film with hydrophobic properties is 5-40 micrometers, preferably 10-20 micrometers, and even more preferably 16-20 micrometers.

[0012] As a further preferred option, the material of the hydrophobic organic film is selected from at least one of polydimethylsilane, epoxy resin, polyaniline, polyvinylidene fluoride, polytetrafluoroethylene, and polymethyl methacrylate.

[0013] Preferably, the thickness of the hydrophobic inorganic layer is 1 to 5 micrometers.

[0014] This invention discloses a method for preparing a superhydrophobic transparent heat-insulating film containing rubidium tungsten bronze. The method involves: preparing rubidium tungsten bronze nanoparticles as an inorganic filler into a slurry, coating it onto glass, and then constructing the superhydrophobic film through a multilayer film method. Specific steps are as follows:

[0015] Step 1: Disperse rubidium tungsten bronze nanoparticles in water to form a dispersion; mix the dispersion with an organic solution at a volume ratio of 1:1.5 to 1.5:1 to obtain a slurry; then coat the slurry onto glass to obtain the first layer of transparent heat-insulating film; the rubidium tungsten bronze powder content in the slurry is 50-100 mg / mL; the organic solution is selected from at least one of polyurethane, polyvinyl alcohol, polyacrylamide, and polyacrylonitrile.

[0016] Step 2: Mix the hydrophobic organic material with the diluent and curing agent, and stir evenly to obtain an organic slurry; then spray the obtained organic slurry onto the first layer of transparent heat insulation film; place the glass in a drying oven and cure at 110-130℃ for 8-15 minutes to obtain a hydrophobic organic layer; the hydrophobic organic material is selected from at least one of polytetrafluoroethylene, polydimethylsiloxane, polyaniline, and epoxy resin; the concentration of the hydrophobic organic material in the organic slurry is 0.05-0.5 g / mL;

[0017] Step 3: Disperse silica particles with a diameter of 15-60 nm into anhydrous ethanol by ultrasonication to obtain a suspension; preferably, the silica content in the dispersion is 1-4 mg / mL. Spray the silica suspension onto a hydrophobic organic layer and air dry to obtain a superhydrophobic transparent heat insulation film.

[0018] In industrial applications, the particle size of rubidium tungsten bronze nanoparticles is 20–500 nm, preferably 50–300 nm.

[0019] This invention disperses nano-sized rubidium tungsten bronze nanoparticles in water to form a dispersion, and then adds the dispersion to an organic liquid and stirs it. This facilitates the uniform dispersion of the nano-sized rubidium tungsten bronze powder, which provides the necessary conditions for obtaining a transparent heat-insulating membrane.

[0020] In step one of this invention, the content of rubidium tungsten bronze in the slurry is controlled to be 50-100 mg / mL because tungsten bronze has the function of regulating viscosity in the slurry and has the function of heat insulation in the film. If the concentration is too high, the dispersion effect of the powder in the slurry will be poor, resulting in a decrease in the visible light transmittance of the film; if it is too low, the slurry will be too thin, making it difficult to coat the film; at the same time, if the content is too low, it will also reduce the heat insulation effect of the film.

[0021] Preferably, the organic solution used in step one of the present invention is polyurethane and / or polyvinyl alcohol.

[0022] Preferably, in step one of this invention, rubidium-tungsten bronze nanoparticles are dispersed in ultrapure water or distilled water to form a dispersion; the dispersion is then mixed with an organic solution at a volume ratio of 1:1.5 to 1.5:1, and after standing, a slurry is obtained; the slurry is then coated onto glass using one of the following methods: spin coating, dip coating, spray coating, or blade coating to obtain a first transparent heat-insulating film. The rubidium-tungsten bronze nanoparticles are prepared by solid-state reaction, hydrothermal, or solvothermal methods, and their morphology is one or more of rod-shaped, sheet-like, or granular forms.

[0023] As a further preferred method, the rubidium tungsten bronze nanopowder is generally dispersed in ultrapure water or distilled water at a ratio of 100 mg of rubidium tungsten bronze powder to 0.6–1.0 mL of water to form a dispersion.

[0024] Preferably, in step two of the present invention, the diluent is selected from at least one of tetrahydrofuran and hexane, and the hydrophobic organic material is selected from at least one of polymethyldioxane and epoxy resin. More preferably, the amount of hydrophobic organic material in the organic slurry is 0.08–0.12 g / ml.

[0025] Preferably, in step two of the present invention, the curing agent is selected from at least one of SYLGARD 184-B (i.e., Dow Corning Sylgard 184 PDMS prepolymer), T31 curing agent, and 593 curing agent, and the amount of organic slurry curing agent used is 0.001 to 0.12 g / ml.

[0026] As a further preferred option, when the hydrophobic organic material in the organic slurry is polydimethylsiloxane, the corresponding curing agent is preferably SYLGARD 184-B, and the concentration is 0.001 to 0.0015 g / mL.

[0027] As a further preferred embodiment, the present invention provides a method for preparing a superhydrophobic transparent heat-insulating film containing rubidium tungsten bronze, comprising the following steps:

[0028] Step 1

[0029] Prepare 1.9–2.1 ml of water with 300 mg of rubidium tungsten bronze powder. Add the prepared nano-rubidium tungsten bronze powder to the water and ultrasonically disperse for at least 25 min to obtain a stable dispersion. Then, mix the dispersion with a 9.5–10.5 wt.% polyvinyl alcohol solution at a volume ratio of 0.95–1.05:0.95–1.05 and let it stand to obtain a tungsten bronze slurry. Next, spin-coat the slurry onto a glass slide at a speed of 1450–1550 r / min for 2.5–3.5 min to obtain a transparent film.

[0030] Step Two

[0031] Prepare an organic slurry by mixing 2g of polydimethylsiloxane with 0.19-0.21g of curing agent and 19-21ml of n-hexane, and stirring thoroughly. Then, spray the obtained organic slurry onto the first layer of transparent heat insulation film. Place the glass in a drying oven and cure it at 115-125℃ for 11-13 minutes to obtain a hydrophobic organic layer with a thickness of 16-20 micrometers.

[0032] Step 3: Disperse silica particles with a diameter of 15-25 nm into anhydrous ethanol using ultrasonication to obtain a suspension with a silica concentration of 1.5-2.5 mg / mL. Then, spray the silica suspension onto a hydrophobic organic layer and allow it to air dry to obtain a superhydrophobic transparent heat insulation film. The silica layer in the superhydrophobic transparent heat insulation film has a thickness of 1.5-2 micrometers.

[0033] The wetting angle of the product obtained by this invention is greater than 150°, and greater than 155° after optimization.

[0034] The product obtained by this invention has a visible light transmittance greater than 54% and a near-infrared shielding rate greater than 84%. Preferably, the visible light transmittance is greater than 62.5%, and the near-infrared shielding rate is greater than or equal to 90%.

[0035] The product obtained by this invention: When a sealed chamber using ordinary glass is irradiated with a 500W tungsten iodine lamp, the temperature rapidly rises to 38.3°C within 30 minutes (starting temperature 15°C). However, when a sealed chamber using a transparent heat-insulating film is irradiated for 30 minutes, the final temperature is 29.3°C.

[0036] This invention is the first to use rubidium tungsten bronze in a transparent heat-insulating film. After optimization, the product achieves a near-infrared shielding rate of ≥90%, a visible light transmittance of ≥60%, and a wetting angle of ≥155° through the synergistic effect of various components and process parameters.

[0037] The rubidium-tungsten bronze-containing superhydrophobic transparent heat-insulating film involved and prepared in this invention can be used as architectural glass or vehicle window glass. Of course, any industry that requires hydrophobic heat insulation and light transmission can also adopt this invention.

[0038] The multi-layered structure design is beneficial for preventing dizziness, especially under strong light conditions, where its anti-dizziness effect is even better. Attached Figure Description

[0039] Figure 1 This is a scanning electron microscope image of the rubidium tungsten bronze nanoparticles used in Comparative Example 1;

[0040] Figure 2 This is a static water contact angle diagram of the transparent heat-insulating film / coating in Comparative Example 2;

[0041] Figure 3 This is a static water contact angle diagram of the superhydrophobic transparent thermal insulation film / coating of Example 1;

[0042] Figure 4 The UV-Vis-NIR spectra of the products obtained in Example 1 and Comparative Example 1 are shown below.

[0043] Figure 5 A schematic diagram of the temperature change of a sealed chamber using the superhydrophobic transparent heat-insulating film / coating of Example 1 as a function of light exposure time;

[0044] Figure 6 Here is a surface SEM image of the transparent heat-insulating film / coating for Comparative Example 3;

[0045] Figure 7 The UV-Vis-NIR spectrum of the superhydrophobic transparent heat-insulating film / coating of Comparative Example 4 is shown below.

[0046] Figure 8 The UV-Vis-NIR spectrum of the superhydrophobic transparent heat-insulating film / coating of Example 2 is shown below.

[0047] Figure 9 The static wetting angle of the superhydrophobic transparent thermal insulation film / coating in Example 2;

[0048] Figure 10 The UV-Vis-NIR spectrum of the superhydrophobic transparent heat-insulating film / coating of Example 3 is shown below.

[0049] Figure 11 The static hydrophobic angle of the superhydrophobic transparent heat-insulating film / coating in Example 3;

[0050] Figure 12The graphs show the test results of the self-cleaning ability of various glass films / coatings, where (a) shows the effect of ordinary glass sheet, (b) shows the effect of the film of Comparative Example 1, (c) shows the effect of the film of Comparative Example 2, and (d) shows the effect of the transparent heat insulation film of Example 3. Detailed Implementation

[0051] The glass sheet used in this invention is conventional sodium calcium glass.

[0052] The chemical formula of the rubidium-tungsten bronze in the examples and comparative examples is: Rb 0.27 WO3, of which rubidium accounts for 9.1% by mass.

[0053] The rubidium-tungsten bronze powder used in this invention is prepared by a solvothermal method. The specific steps are as follows: First, 2 mmol of sodium tungstate dihydrate is dissolved in 60 ml of deionized water. Then, 3 mmol of citric acid and 10 mmol of glucose are added to the solution sequentially, and the mixture is stirred for 10 min to ensure complete dissolution. Next, a certain amount of hydrochloric acid is quickly added to the above solution. The solution turns yellow and forms a yellow gel. After stirring for another 30 min, the solution is poured into a 100 ml hydrothermal reactor liner for hydrothermal reaction. The hydrothermal holding temperature is 120℃, and the hydrothermal time is 7 h. After the hydrothermal reaction is completed, the obtained precipitate is washed by centrifugation with deionized water and alcohol, and then vacuum dried at 60℃ for 8 h to finally obtain yellow-green tungsten trioxide hydrate (WO3·H2O) powder. Then, an appropriate amount of precursor powder is weighed and placed in 50 ml of anhydrous ethanol, and ultrasonically dispersed for 30 min to form a uniformly dispersed suspension. Then, a certain amount of RbCl is weighed and dissolved in 13 ml of acetic acid. The acetic acid solution was then poured into an ethanol dispersion containing the precursor, stirred thoroughly, and then poured into a 100 ml hydrothermal reactor liner for hydrothermal reaction. The hydrothermal temperature was 220℃, and the hydrothermal time was 24 h. After the hydrothermal reaction, the obtained blue precipitate was washed (twice with deionized water and alcohol), centrifuged, filtered, and vacuum dried to finally obtain blue Rb. 0.27 WO3 powder.

[0054] Comparative Example 1

[0055] 300 mg of rubidium tungsten bronze powder (particle size 126 nm) was weighed and sonicated for 30 min to uniformly disperse the powder in 2 ml of water, forming a stable dispersion. This dispersion was then mixed with 10 wt.% PVA solution at a volume ratio of 1:1 using high-speed stirring. After standing, a tungsten bronze slurry was obtained. An appropriate amount of the slurry was then spin-coated onto a glass slide at a speed of 1500 rpm for 3 min, ultimately yielding a deep blue transparent film. Figure 1 The morphology of the rubidium tungsten bronze powder used is mainly granular, with a small amount of rod-shaped powder. Figure 4It can be seen that the visible light transmittance of the film is 55.3%, but the static water contact angle of the film is 53.0°, which indicates that it is hydrophilic. This is due to the hydroxyl groups present in the PVA polymer chain and the oxygen vacancies in the tungsten bronze powder.

[0056] Comparative Example 2

[0057] Weigh 300 mg of rubidium tungsten bronze powder (particle size 143 nm), and sonicate for 30 min to uniformly disperse the powder in 2 ml of water to form a stable dispersion. Mix this dispersion with 10 wt.% PVA solution at a volume ratio of 1:1 using high-speed stirring, and allow it to stand to obtain a tungsten bronze slurry. Then, apply an appropriate amount of the slurry to a glass slide using a spin coating method, controlling the rotation speed at 1500 r / min for 3 min, ultimately obtaining a deep blue transparent film. A hydrophobic film is then coated on top of this film. First, weigh 2 g of polydimethylsiloxane (PDMS) and 0.2 g of curing agent (SYLGARD 184-B) and add them to 20 ml of n-hexane, stirring until homogeneous. Then, use a pipette to draw 2 ml of PDMS solution, pour it into an airbrush, and slowly move the airbrush to uniformly spray the PDMS solution onto the tungsten bronze PVA film. After curing, a double-layer film / coating is finally obtained. Figure 2 The static contact angle of this film / coating is only 118°. The hydrophobic properties of the film are improved after PDMS coating. The visible light transmittance of this film is 69.5%.

[0058] Example 1

[0059] Weigh 300 mg of rubidium tungsten bronze powder (particle size 126 nm), and sonicate for 30 min to uniformly disperse the powder in 2 ml of water to form a stable dispersion. Mix this dispersion with 10 wt.% polyvinyl alcohol solution at a volume ratio of 1:1 using high-speed stirring. After standing, obtain a tungsten bronze slurry. Then, apply an appropriate amount of the slurry onto a glass slide using a spin coating method, controlling the rotation speed at 1500 r / min for 3 min, ultimately obtaining a deep blue transparent film (1.0 μm thick). A hydrophobic film is then coated onto this film. First, weigh 2 g of polydimethylsiloxane (PDMS) and 0.2 g of curing agent (SYLGARD 184-B) and add them to 20 ml of n-hexane, stirring until homogeneous. Then, use a pipette to draw 2 ml of the PDMS solution, pour it into an airbrush, and slowly move the airbrush to uniformly spray the PDMS solution onto the tungsten bronze PVA film. The sprayed film was cured in a 120°C drying oven for 12 minutes to obtain a PDMS coating with a thickness of 18 micrometers. A silica-alcohol suspension was then sprayed onto this PDMS coating. The silica-alcohol suspension consisted of 40 mg of silica (particle size 20 nm) ultrasonically dispersed in 20 ml of anhydrous ethanol. The spraying process parameters were the same as those for the PDMS solution, resulting in a silica layer with a thickness of 1.8 micrometers. The silica particles used were derived from hydrophobically modified fumed silica in a liquid phase. The specific steps were as follows: 1 g of fumed silica powder was dispersed in 20 ml of tetrahydrofuran solution by stirring for 10 minutes. Then, 2 g of hexamethyldisilazane was added to the suspension, and stirring continued at room temperature for 4 hours. The powder was washed with alcohol, centrifuged to precipitate, and dried to obtain the hydrophobically modified powder.

[0060] Figure 3 The static wetting angle of the superhydrophobic transparent thermal insulation film / coating is shown. It can be seen from the figure that the wetting angle is 156° (greater than 150°) and has superhydrophobicity. Figure 4 The UV-Vis-NIR spectrum of the film in Example 1 is shown in the figure. It can be observed from the figure that the maximum visible light transmittance of the film / coating is 62.7%, the minimum near-infrared transmittance is 7.1%, and the maximum near-infrared shielding rate is 92.9%. Compared with Comparative Example 1, the film of Example 1 has a higher overall transmittance. Figure 4 This demonstrates the heat insulation effect of the film / coating used in Example 1. Figure 5 It can be seen that the temperature of a sealed room using ordinary glass rapidly rises to 38.3°C under 500W tungsten iodine lamp illumination. In contrast, the temperature of a sealed room using a transparent heat-insulating film only reaches 29.3°C after 30 minutes of illumination. Compared to blank glass, this film effectively reduces the temperature of the sealed room, indicating that it has good heat insulation properties.

[0061] Comparative Example 3

[0062] Weigh 300 mg of rubidium tungsten bronze powder (particle size 126 nm), and sonicate for 30 min to uniformly disperse the powder in 2 ml of water to form a stable dispersion. Mix this dispersion with a 10 wt.% polyvinyl alcohol solution at a volume ratio of 1:1 using high-speed stirring. After standing, obtain a tungsten bronze slurry. Then, apply an appropriate amount of the slurry onto a glass slide using a spin coating method, controlling the rotation speed at 1500 r / min for 3 min, ultimately obtaining a deep blue transparent film (1.0 μm thick). A hydrophobic film is then coated onto this film. First, weigh 2 g of polydimethylsiloxane (PDMS) and 0.2 g of curing agent (SYLGARD 184B) and add them to 20 ml of n-hexane, stirring until homogeneous. Then, use a pipette to draw 2 ml of the PDMS solution, pour it into an airbrush, and slowly move the airbrush to uniformly spray the PDMS solution onto the tungsten bronze PVA film. The sprayed film was placed in a drying oven at 120°C for 6 minutes to cure, resulting in a PDMS coating with a thickness of 18 micrometers. A silica-alcohol suspension was then sprayed onto this PDMS coating. The silica-alcohol suspension consisted of 40 mg of silica (20 nm particle size) ultrasonically dispersed in 20 ml of anhydrous ethanol; the spraying process parameters were the same as those for the PDMS solution. After drying for another 30 minutes, a silica layer with a thickness of 1.8 micrometers was obtained.

[0063] The final film / coating had a visible light transmittance of only 28.9% and a near-infrared shielding rate of 93.5%. The low visible light transmittance of the film / coating is due to its overall non-uniformity. Figure 6 For the surface morphology of Comparative Example 3, obvious inhomogeneity can be observed in the figure. To the left of the white line, there are fewer silica particles on the film / coating surface, while on the right side of the film, the silica particle content is higher. The contact angle of this film / coating is 136.3° (less than 150°), indicating that the film does not have superhydrophobic properties.

[0064] Comparative Example 4

[0065] Weigh 300 mg of rubidium tungsten bronze powder (particle size 126 nm), and sonicate for 30 min to uniformly disperse the powder in 2 ml of water to form a stable dispersion. Mix this dispersion with a 10 wt.% polyvinyl alcohol solution at a volume ratio of 1:2 using high-speed stirring. After standing, obtain a tungsten bronze slurry. Then, apply an appropriate amount of the slurry onto a glass slide using a spin coating method, controlling the rotation speed at 1500 r / min for 3 min, ultimately obtaining a deep blue transparent film (0.8 μm thick). A hydrophobic film is then coated onto this film. First, weigh 2 g of polydimethylsiloxane (PDMS) and 0.2 g of curing agent (SYLGARD184-B) and add them to 20 ml of n-hexane, stirring until homogeneous. Then, use a pipette to draw 2 ml of the PDMS solution, pour it into an airbrush, and slowly move the airbrush to uniformly spray the PDMS solution onto the tungsten bronze PVA film. The sprayed film was placed in a drying oven at 120°C for 12 minutes to cure, resulting in a PDMS coating with a thickness of 18 micrometers. A silica-alcohol suspension was then sprayed onto this PDMS coating. The silica-alcohol suspension consisted of 10 mg of silica ultrasonically dispersed in 20 ml of anhydrous ethanol; the spraying process parameters were the same as those for the PDMS solution. After drying for another 30 minutes, a silica layer was obtained.

[0066] Figure 7 The image shows the UV-Vis-NIR spectrum of the superhydrophobic transparent heat-insulating film / coating. The visible light transmittance of this film / coating is 44.4%, the near-infrared shielding rate is 82.3%, and the contact angle is 145.2° (less than 150°). This superhydrophobic transparent heat-insulating film / coating exhibits both low visible light transmittance and low contact angle.

[0067] Example 2

[0068] 240 mg of heat-treated rubidium tungsten bronze powder (particle size 126 nm) was weighed and sonicated for 30 min to uniformly disperse the powder in 2 ml of water, forming a stable dispersion. This dispersion was then mixed with a 10 wt.% polyvinyl alcohol solution at a volume ratio of 1:1 using high-speed stirring. After standing, a tungsten bronze slurry was obtained. An appropriate amount of the slurry was then spin-coated onto a glass slide at a speed of 1500 rpm for 3 min, resulting in a deep blue transparent film (1.2 μm thick). A hydrophobic film was then coated onto this film. First, weigh 2g of polydimethylsiloxane (PDMS) and 0.2g of curing agent (SYLGARD184B) and add them to 4ml of tetrahydrofuran. Stir well, then use a spin coater to spin-coat a layer onto a dark blue transparent film, controlling the spin speed at 2500 rpm for 40 seconds. The film is then placed in a 120℃ drying oven for curing for 10 minutes to obtain a PDMS coating with a thickness of 15 micrometers. Next, a silica alcohol suspension is sprayed onto this PDMS coating. The alcohol suspension is composed of 80mg of silica (particle size 20nm) ultrasonically dispersed in 20ml of alcohol. During spraying, 2ml of this suspension is used, and the spray is performed at 27psi pressure and a distance of 20cm. After spraying, the film is placed in a 120℃ drying oven for curing to obtain a silica layer with a thickness of 1.0 micrometer.

[0069] Figure 6 The UV-Vis-NIR curves of the transparent heat-insulating film / coating prepared in Example 2 show that its maximum near-infrared shielding rate is 85.9% and its maximum visible light transmittance is 54.8%. Figure 7 The static contact angle of the superhydrophobic transparent heat insulation film / coating in Example 2 is shown in the figure. The wetting angle is 165°, indicating that it has superhydrophobic properties.

[0070] Example 3

[0071] 300 mg of heat-treated rubidium tungsten bronze powder (particle size 150 nm) was weighed and sonicated for 30 min to uniformly disperse the powder in 2 ml of water, forming a stable dispersion. This dispersion was then mixed with 10 wt.% polyurethane solution at a volume ratio of 1:1 using high-speed stirring. After standing, a tungsten bronze slurry was obtained. An appropriate amount of the slurry was then spin-coated onto a glass slide at a speed of 1500 rpm for 3 min, ultimately obtaining a deep blue transparent film (1.3 μm thick). A hydrophobic film was then coated onto this film. First, weigh 2g of polydimethylsiloxane (PDMS) and 0.2g of curing agent (SYLGARD184B) and add them to 4ml of n-hexane. Stir well, then use a spin coater to spin-coat a layer onto a dark blue transparent film, controlling the spin speed at 2500 rpm for 40 seconds. The film is then placed in a 120℃ drying oven for curing for 10 minutes to obtain a PDMS coating with a thickness of 20 micrometers. Next, a silica alcohol suspension is sprayed onto this PDMS coating. The alcohol suspension is composed of 60mg of silica (particle size 20nm) ultrasonically dispersed in 20ml of alcohol. During spraying, 2ml of this suspension is used, and the spraying is performed at 27psi pressure and a distance of 20cm. After spraying, the film is placed in a 120℃ drying oven for curing to obtain a silica layer with a thickness of 1.0 micrometer.

[0072] Figure 8 The UV-Vis-NIR curves of the transparent heat-insulating film / coating prepared in Example 2 are shown in the figure. It can be seen from the figure that its maximum near-infrared shielding rate is 84.5% and its maximum visible light transmittance is 66.2%. Figure 9 The static contact angle of the superhydrophobic transparent heat-insulating film / coating in Example 3 is shown in the figure. The wetting angle is 158°, indicating that it has superhydrophobic properties. Figure 10 This demonstrates the self-cleaning properties of the superhydrophobic transparent heat-insulating film / coating; water droplets can easily roll off the superhydrophobic surface, carrying away contaminants in the process. Figure 10 As can be seen, in Example 3, no contaminants remained in the path through which the water flowed on the membrane.

[0073] Example 4

[0074] Weigh 260 mg of rubidium tungsten bronze powder (particle size 150 nm), and sonicate for 30 min to uniformly disperse the powder in 2 ml of water to form a stable dispersion. Mix this dispersion with a 10 wt.% polyvinyl alcohol solution at a volume ratio of 1:1 using high-speed stirring. After standing, obtain a tungsten bronze slurry. Then, apply an appropriate amount of the slurry onto a glass slide using a spin coating method, controlling the rotation speed at 1500 r / min for 3 min, ultimately obtaining a deep blue transparent film (0.9 μm thick). A hydrophobic film is then coated onto this film. First, weigh 2 g of epoxy resin (E-44), 0.6 g of curing agent (T-31), and 10 mg of silica and add them to 20 ml of acetone, stirring until homogeneous. Then, use a pipette to draw 2 ml of the E-44 solution, pour it into an airbrush, and slowly move the airbrush to uniformly spray the E-44 solution onto the tungsten bronze polyvinyl alcohol film. The sprayed film was placed in an 80°C drying oven for 12 minutes to cure, resulting in a 10-micron thick epoxy resin coating. A layer of silica-alcohol suspension was then sprayed onto this epoxy resin coating. The silica-alcohol suspension consisted of 40 mg of silica ultrasonically dispersed in 20 ml of anhydrous ethanol; the spraying process parameters were the same as those for the E-44 solution. After drying for another 30 minutes, the final superhydrophobic transparent thermal insulation film was obtained.

[0075] The visible light transmittance of this superhydrophobic transparent heat-insulating film / coating is 50.0%, and the near-infrared shielding rate is 85.1%. The contact angle of this film / coating is 151.8°, exhibiting good hydrophobic properties.

[0076] Comparative Example 5

[0077] All other conditions were identical to those in Example 1, except that a 19.8-micron thick silica layer was directly prepared after obtaining a deep blue transparent film (1.0 micrometer thick). This omitted the step of "coating a hydrophobic film on top of this film. First, weigh 2g of polydimethylsiloxane (PDMS) and 0.2g of curing agent (SYLGARD 184-B) and add them to 20ml of n-hexane, stirring until homogeneous; then, use a pipette to draw 2ml of the PDMS solution, pour it into an airbrush, and slowly move the airbrush to evenly spray the PDMS solution onto the tungsten bronze PVA film. Place the sprayed film in a 120°C drying oven for curing for 12 minutes to obtain a 18-micron thick PDMS coating." The resulting product had a visible light transmittance of 13% and a near-infrared shielding rate of 97%. The contact angle of the film was 168.3°.

[0078] Comparative Example 6

[0079] All other conditions were identical to those in Example 1, except that: 300 mg of rubidium tungsten bronze powder (particle size 126 nm) was weighed and sonicated for 30 min to uniformly disperse the powder in 1 ml of water, forming a stable dispersion. This dispersion was then mixed with a 10 wt.% polyvinyl alcohol solution at a volume ratio of 1:3 using high-speed stirring. After standing, a tungsten bronze slurry was obtained. An appropriate amount of the slurry was then spin-coated onto a glass slide at a speed of 1500 r / min for 3 min, ultimately yielding a deep blue transparent film.

[0080] The resulting product has a visible light transmittance of 67.5% and a near-infrared shielding rate of 42.5%. The contact angle of the film is 156°.

[0081] Comparative Example 7

[0082] 300 mg of rubidium tungsten bronze powder (particle size 126 nm) was weighed and ultrasonically dispersed in 2 ml of water for 30 min to form a stable dispersion. This dispersion was then mixed with a 10 wt.% polyvinyl alcohol solution at a volume ratio of 1:1 using high-speed stirring. After standing, a tungsten bronze slurry was obtained. An appropriate amount of this slurry was then spin-coated onto a glass slide at a speed of 1500 rpm for 3 min, resulting in a deep blue transparent film (1.0 μm thick). A silica-alcohol suspension was then directly sprayed onto this polyvinyl alcohol layer. 2 ml of the silica-alcohol suspension was poured into an airbrush and slowly sprayed onto the polyvinyl alcohol film. The silica-alcohol suspension consisted of 40 mg of silica (particle size 20 nm) ultrasonically dispersed in 20 ml of anhydrous ethanol, resulting in a silica layer with a thickness of 1.8 μm. The visible light transmittance of the product was 27.5%, and the near-infrared shielding rate of the film was 95.9%. The contact angle of the film is 148.5°.

[0083] As can be seen from the examples and comparative examples, the present invention requires the synergistic effect of structural and preparation process parameters to obtain excellent products.

Claims

1. A superhydrophobic transparent thermal barrier film comprising rubidium tungsten bronze, characterized in that: The super-hydrophobic transparent heat insulation film contains a heat insulation layer and a hydrophobic layer, the heat insulation layer contains tungsten bronze nano-powder, and the hydrophobic layer is attached to the heat insulation layer. The super-hydrophobic transparent heat insulation film is prepared by coating a slurry of rubidium tungsten bronze nano-powder as inorganic filler on glass and constructing the film in multiple layers; the specific steps include: Step one: disperse rubidium tungsten bronze nano-powder in water to form a dispersion liquid; mix the dispersion liquid and an organic solution in a volume ratio of 1:1.5-1.5:1 by stirring to obtain a slurry; then coat the slurry on glass to obtain a first layer of transparent heat insulation film; in the slurry, the content of rubidium tungsten bronze powder is 50-100 mg / mL; the organic solution is at least one selected from polyurethane, polyvinyl alcohol, polyacrylamide and polyacrylonitrile; Step two: mix a hydrophobic organic substance with a diluent and a curing agent by stirring to obtain an organic slurry; then spray the obtained organic slurry on the first layer of transparent heat insulation film; place the glass in a drying oven and cure at 110-130 ℃ for 8-15 min to obtain a hydrophobic organic substance layer; the hydrophobic organic substance is at least one selected from polytetrafluoroethylene, polydimethylsiloxane, polyaniline and epoxy resin; the concentration of the hydrophobic organic substance in the organic slurry is 0.05-0.5 g / mL; Step three: ultrasonically disperse silica with a particle size of 15-60 nm in anhydrous ethanol to obtain a suspension; the content of silica in the dispersion liquid is 1-4 mg / mL; spray the silica suspension on the hydrophobic organic substance layer and naturally air dry to obtain a super-hydrophobic transparent heat insulation film.

2. The superhydrophobic transparent thermal insulation film containing rubidium tungsten bronze according to claim 1, characterized in that: The particle size of the rubidium tungsten bronze nano-powder used in the thermal insulation layer is 20-500 nm; the chemical formula of the rubidium tungsten bronze is: Rb 0.27 WO3.

3. The superhydrophobic transparent thermal insulation film containing rubidium tungsten bronze according to claim 1, characterized in that: The thickness of the heat insulation layer is greater than the particle size of the used rubidium tungsten bronze nano-powder, and is 0.5-10 microns.

4. The superhydrophobic transparent thermal insulation film containing rubidium tungsten bronze according to claim 1, characterized in that: The thickness of the hydrophobic organic substance layer is 5-40 microns. The material of the organic film with hydrophobic properties is at least one selected from polydimethylsilane, epoxy resin, polyaniline, polyvinylidene fluoride, polytetrafluoroethylene and polymethyl methacrylate.

5. The superhydrophobic transparent thermal insulation film containing rubidium tungsten bronze according to claim 4, characterized in that: The thickness of the hydrophobic organic substance layer is 10-20 microns.

6. The superhydrophobic transparent thermal barrier film containing rubidium tungsten bronze according to claim 4, characterized in that: The thickness of the hydrophobic organic substance layer is 16-20 microns.

7. The super-hydrophobic transparent heat insulation film containing rubidium tungsten bronze according to claim 1, characterized in that: The particle size of the rubidium tungsten bronze nano-powder is 20-500 nm; Disperse the nano-level rubidium tungsten bronze nano-powder in water to form a dispersion liquid, and then add the dispersion liquid to an organic liquid and stir; In step one, the content of rubidium tungsten bronze in the slurry is controlled to be 50-100 mg / mL; In step one, the organic solution used is polyurethane and / or polyvinyl alcohol; In step two, the diluent is at least one selected from tetrahydrofuran and hexane, and the hydrophobic organic substance is at least one selected from polymethylsilane and epoxy resin; the amount of the hydrophobic organic substance in the organic slurry is 0.08-0.12 g / ml; In step two, the curing agent is at least one selected from SYLGARD 184-B, T31 curing agent and 593 curing agent; the amount of the curing agent in the organic slurry is 0.001-0.12 g / ml.

8. The superhydrophobic transparent thermal barrier film containing rubidium tungsten bronze according to claim 1, characterized in that: The steps include: Step one According to the proportion of 300 mg of rubidium tungsten bronze powder to 1.9-2.1 ml of water, the prepared nanometer rubidium tungsten bronze powder is added to water, and after ultrasonic dispersion for at least 25 min, a stable dispersion liquid is obtained. Then, the dispersion liquid is mixed with 9.5-10.5 wt.% of a polyvinyl alcohol solution at a volume ratio of 0.95-1.05:0.95-1.05, and after standing, a tungsten bronze slurry is obtained. Then, the slurry is coated on a glass sheet by spin coating, the rotation speed is controlled at 1450-1550 r / min, and the rotation time is 2.5-3.5 min, and finally a transparent film is obtained; Step two According to the proportion of 2 g of polydimethylsiloxane to 0.19-0.21 g of a curing agent and 19-21 ml of n-hexane, the polydimethylsiloxane, SYLGARD 184-B, and n-hexane are prepared and stirred uniformly to obtain an organic slurry. The obtained organic slurry is then sprayed onto the first layer of transparent heat insulation film. The glass is placed in a drying oven and cured at 115-125℃ for 11-13 min to obtain a hydrophobic organic layer with a thickness of 16-20 microns. Step three: Silica with a particle size of 15-25 nm is ultrasonically dispersed in anhydrous ethanol to obtain a suspension, and the concentration of silica in the suspension is 1.5-2.5 mg / mL. The silica suspension is then sprayed onto the hydrophobic organic layer and naturally air-dried to obtain a super-hydrophobic transparent heat insulation film. In the super-hydrophobic transparent heat insulation film, the thickness of the silica layer is 1.5-2 microns.

9. The superhydrophobic transparent thermal barrier film containing rubidium tungsten bronze according to any one of claims 1-8, characterized in that: The wetting angle of the product is greater than 150°. The product has a visible light transmittance of greater than 54% and a near-infrared shielding rate of greater than 84%. The product is used to prepare a transparent heat insulation film for a sealed room. When the transparent heat insulation film is used in a sealed room with an initial temperature of 15℃, the temperature is ultimately 29.3℃ after 30 min of irradiation.

10. Use of a superhydrophobic transparent thermal insulation film comprising rubidium tungsten bronze according to any one of claims 1 to 4, characterized in that: The application includes its use as building glass or vehicle window glass.

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