CN115703933A

CN115703933A - Nano microsphere, preparation method thereof and application of nano microsphere in thermal insulation coating

Info

Publication number: CN115703933A
Application number: CN202210924699.5A
Authority: CN
Inventors: 杨晶磊; 罗文君; 张伟滨
Original assignee: Hong Kong University of Science and Technology HKUST
Current assignee: Hong Kong University of Science and Technology HKUST
Priority date: 2021-08-03
Filing date: 2022-08-02
Publication date: 2023-02-17
Anticipated expiration: 2042-08-02
Also published as: CN115703933B

Abstract

The invention relates to hollow structure nano microspheres comprising an outer shell formed by silica nano particles and an inner shell formed by plasma nano particles, a preparation method thereof and application in a coating composition. The insulating glass coated with the coating composition of the present invention is capable of blocking at least 98% of ultraviolet light and at least 90% of near infrared light, and has a visible light transmittance of not less than 70%.

Description

Nano microsphere, preparation method thereof and application of nano microsphere in thermal insulation coating

Technical Field

The invention relates to the field of coatings, in particular to a hollow core-shell structured nano microsphere comprising an outer shell formed by silicon dioxide nano particles and an inner shell formed by plasma nano particles, a preparation method thereof and application thereof in a thermal insulation coating.

Background

The thermal barrier coating can effectively prevent heat from sunlight penetrating through a building window, thereby reducing the indoor ambient temperature. Conventional thermal barrier coatings achieve thermal insulation by reducing the amount of heat transferred from the exterior surface to the interior of the room, and such thermal barrier coatings are based primarily on materials with low thermal conductivity, such as ceramic particles and polymeric resins. The transparent heat-insulating coating is coated on the glass window, so that near infrared and ultraviolet rays can be strongly shielded, the solar heat absorbed by the window is greatly reduced, and the transparent heat-insulating coating is widely explored and applied in the aspect of building energy conservation. The thermal insulation properties of building windows are increasingly attracting considerable attention in energy saving applications, making a significant contribution to the annual cooling load reduction of 10% to 30% in the summer of the individual climate zones.

Existing thermal barrier coatings consist primarily of a polymer matrix and incorporated inorganic fillers and have limited absorption bands in the Near Infrared (NIR) region. In recent years, with the rapid development of nano material research and synthesis technology, various nano particles and hollow particles gradually appear, and the development of heat insulation coatings is promoted.

U.S. Pat. No. 10913858B2 discloses an aqueous heat-insulating coating material in which silica is uniformly dispersed in a resin as a heat-insulating agent by a sol-gel method to eliminate the problem of particles aggregating to form coarse particles, thereby simplifying the preparation process and preventing the influence of dispersion unevenness. Since the silica dispersion has good fineness and has a particle size of 30.1m ² G to 100m ² The large specific surface area per gram, therefore, when the water-based heat insulation coating is applied to the building surface, the formed coating has compact structure, smooth surface and high surface reflectivity of more than 85 percent. Such a coating layer can effectively block infrared rays and provide excellent heat insulation effect, dirt resistance and durability.

Us 20160160053A1 discloses a method of making and using a nanocomposite for coating glass consisting of a first metal oxide bridging a silicone oil moiety and an anionic surfactant moiety and a second metal oxide bonded to the silicone oil moiety. The composite material may be manufactured by heating the first metal oxide and the second metal oxide with the silicone oil, and then adding a mixture of the surfactant and the oxidizing solution. Glass coated with this composite material can transmit visible light, absorb some ultraviolet light, and reflect some near infrared light. The optical properties of the coated glass can be used to reduce the amount of heat in the enclosed area of the glass by reducing the amount of infrared and ultraviolet light transmitted through the glass. Although the adhesion between the coating and the glass substrate is improved, the complex synthesis steps make it difficult to apply to large area surfaces.

Us patent 4510190 discloses a transparent thermal barrier coating which has a neutral effect on the transmission and appearance of the glass sheets used for thermal insulation. The coating is formed of a bismuth oxide-silver-bismuth oxide multilayer system in which a more electronegative substance (i.e., a substance having a higher standard potential) is added to the bismuth oxide layer to avoid blackening under ultraviolet radiation. The bismuth oxide layers act as reflection-reducing layers in the multilayer system, i.e. they significantly increase the transmission in the visible region. Due to the suitable layer thickness, this bismuth oxide-silver-bismuth oxide multilayer system is capable of forming an excellent thermal barrier coating on a glass substrate.

Us patent No. 5099621A relates to the use of a conductive polymer material to selectively control the light transmittance through a transparent or translucent plate or film according to wavelength; and more particularly, to the use of conductive polymer materials to provide a window blind having high transmittance in the visible range and high reflectance and absorption in the near and far infrared ranges. The coating solution can be readily applied to a substrate by a variety of low cost and efficient methods known in the art, such as spin coating, spray coating, dip coating or extrusion coating. The cost of the heat insulating window unit is significantly reduced, the manufacturing process is simplified, and the reliability and operating efficiency of the unit are improved.

U.S. Pat. No. 20130168595A1 relates to a nano heat insulation coating and a preparation method thereof, and more particularly relates to a blended solid solution of nano antimony tin oxide and nano vanadium oxide. The method comprises the following steps: mixing and stirring the nano metal oxide and the stirring-assistant liquid to form mixed paste, filtering and drying the mixed paste to form a dried mixed block; calcining the dried mixed bulk to form a metal oxide/silicon oxide solid solution bulk; adding dispersion aid liquid and mixing aid liquid, mixing and then mechanically stirring, and carrying out ultrasonic resonance and high-pressure homogenization to form the heat insulation coating which is suitable for being coated on glass to achieve the special heat insulation effect. Such a preparation process is not only time consuming but also more costly to manufacture, since the calcination and homogenization processes require extremely high temperatures and pressures, respectively.

Us patent No. 20120121886A1 discloses an infrared reflective coating composition comprising polymeric hollow particles, pigment particles and at least one polymeric binder. The volume average particle size of the polymeric hollow particles is from 0.3 microns to 1.6 microns, significantly larger than conventional nanoparticulate fillers. The coating composition is suitable for use in a number of settings, such as exterior architectural or industrial applications. The present invention also provides a coating material comprising at least one coating film derived from the coating composition. In architectural applications, the coating composition is suitable for coating exterior glazing surfaces. The coating composition applied to the substrate can be dried or allowed to dry over a wide temperature range of 1 ℃ to 95 ℃.

U.S. Pat. No. 2020023977 A1 discloses an alkyd-containing polymer dispersion dispersed in water for forming a primary aqueous coating composition. The resulting waterborne coating composition comprises from about 2% to about 30% by weight of one or more thermal insulating fillers with the balance being an alkyd-containing dispersion, such that the coating composition comprises from about 30% to about 80% by weight water and from about 2% to about 50% by weight alkyd-containing polymer. A coating layer formed from the coating composition exhibits heat resistance and a thermal conductivity of less than 100 mW/mK.

U.S. Pat. Nos. 8304099B2 and 8986851B2 disclose a composition and a manufacturing method of a transparent heat insulating material formed of tungsten oxide co-doped with metal cations and halogen anions, the transparent heat insulating material consisting of M _x WO _y A _z Wherein M is at least one element of alkali metals, and A is halogen. The transparent insulating material has a visible light transmission of greater than about 70% and an infrared light blocking ratio of greater than about 70%. Compared with the traditional transparent heat insulation film containing undoped tungsten oxide or tungsten oxide doped with metal ions, the transparent heat insulation film can enhance the heat insulation capability and maintain the same level of visible light transmittance as the traditional film. However, the introduction of halogen elements can cause potential harm to the surrounding environment and human body.

U.S. Pat. No. 7252785B2 discloses a composition for producing a thermal barrier coating comprising at least one radiation absorbing compound and at least one IR reflecting component. The IR reflecting characteristic is due to at least a portion of the oriented cholesteric polymer or at least a portion of the oriented polymer obtainable by polymerization of monomers having a helical superstructure pitch corresponding to a wavelength in the infrared spectral range after the IR reflecting component is oriented and cured. It is known that materials which reflect thermal radiation significantly can be used for thermal insulation, in particular for shielding thermal radiation in the wavelength range from 800nm to 2000 nm. In this invention, curing refers to polymerization of monomers and crosslinking of five polymers. Thus, while these compositions are known to provide insulative properties when cured, their solvent sensitivity, flexibility and scratch resistance are not ideal.

At present, the common feature of most existing production methods for infrared and ultraviolet shielding coatings for thermal insulation purposes is the application of a hybrid coating comprising ceramic nanofillers, hollow particles, aqueous or solvent based resins and coating aids via conventional coating processes such as spray coating, dip coating and deposition methods. However, in addition to the white and visible thickness of the coating, the lack of the ability to specifically block NIR light also limits further use of such products. Over the past few decades, efforts have been made to develop hybrid coating technologies and their applications, which have also attracted increasing attention in the area of construction and building materials.

However, as disclosed in various documents and patents, some nano inorganic particles and hollow particles, such as silica, hollow silica, calcium oxide, etc., do provide some shielding and reflection of UV light and NIR light, and thus can effectively insulate a part of thermal energy from sunlight. However, common nanomaterials used for thermal insulation purposes only interact with NIR light of a limited wavelength range and also reflect part of the visible light. For example, inorganic nanoparticles having a strong infrared absorption ability are mainly indium-based conductive oxides, but they can exhibit excellent shielding properties only at wavelengths greater than 1500 nm.

Accordingly, there remains a great need in the art for thermal barrier coatings having excellent absorption/barrier capabilities in the Near Infrared (NIR) region.

Disclosure of Invention

As previously mentioned, the thermal insulation properties of architectural windows have attracted considerable attention in energy saving applications. The main object of the present invention is to disclose a coating composition which, when applied as a coating to the surface of glass, is capable of selectively absorbing almost all of the NIR and UV in the solar spectrum and maintaining a high visible light transmission. The present inventors found that by combining or surface-modifying plasmonic nanoparticles to form nanospheres having a hollow core-shell structure and then combining them with an aqueous resin or the like to prepare a coating composition, the coating thus prepared exhibits excellent properties in near infrared/ultraviolet light blocking, uniformity, leveling, coatability, applicability and the like, thereby leading to the present invention.

Thus, in a first aspect of the invention, there is provided a nanosphere having a hollow core-shell structure comprising an outer shell formed from silica nanoparticles and an inner shell formed from first plasmonic nanoparticles.

In a second aspect, there is provided a method of preparing the nanosphere of the first aspect, comprising:

1) Primary coating step: coating the substrate microsphere with the plasma nano-particles to form a substrate @ plasma nano-particle core-shell microsphere;

2) Secondary coating step: coating the substrate @ plasma nanoparticle core-shell microspheres with silicon dioxide nanoparticles to form substrate @ plasma nanoparticles @ silicon dioxide nanoparticle core-shell microspheres;

3) And (3) calcining: calcining at 400-600 ℃ to remove the substrate microspheres and obtain the nano microspheres with hollow core-shell structures.

In a third aspect, there is provided a coating composition consisting of, based on the total weight of the coating composition:

(A) 50 to 75 weight percent of a water-borne resin;

(B) 11 to 35 wt% of a nanoparticle slurry comprising the nanospheres of the first aspect or the nanospheres prepared by the method of the second aspect or a combination comprising at least two second plasmonic nanoparticles; and

(C) 4 to 15% by weight of auxiliaries.

In a fourth aspect, there is provided a thermal insulation comprising a transparent substrate and the coating composition of the third aspect applied to a surface of the transparent substrate.

In a fifth aspect, there is provided a method of preparing the coating composition of the third aspect, comprising:

(1) Preparing nanoparticle slurry, wherein the nanoparticle or at least two second plasma nanoparticles, a dispersing agent and a pH regulator are dispersed in deionized water, and the nanoparticle slurry is formed through stirring, ball milling and ultrasonic treatment;

(2) Adding the obtained nano-particle slurry into water-based resin, and stirring to form an initial heat insulation coating; and

(3) An auxiliary agent is added to the initial thermal barrier coating to form a final coating composition.

The invention provides a coating composition with excellent near infrared light/ultraviolet light barrier property. The inventor finds that the organic-inorganic blended coating can absorb almost all ultraviolet light and near infrared light (with the wavelength of more than 780 nm) with selected wavelength to insulate heat, can maintain the visible light transmittance of the coating, has the potential of being applied to windows and curtain walls of buildings, and provides an ideal potential candidate material for building energy conservation.

The heat-insulating glass coated with the coating composition of the invention can absorb not less than 98% of ultraviolet light and not less than 70%, even not less than 90% of near infrared light, and has at least 70% of visible light transmittance, thereby being capable of realizing the temperature difference between the interior and the exterior of a building from 8 ℃ to 10 ℃. Therefore, the coating composition and the insulating glass of the present invention can make a great contribution to a reduction in cooling load of 10% to 30% throughout the summer in subtropical climate zones.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.

FIG. 1 shows plasmonic nanoparticles ATO, ITO, and Cs _x WO ₃ Transmittance curves in the ultraviolet, visible and infrared spectral ranges.

Fig. 2 shows a flow diagram for preparing a nanosphere having a hollow core-shell structure according to an embodiment of the present invention.

FIG. 3 shows nanospheres prepared according to one embodiment of the present invention: (a) Scanning Electron Microscope (SEM) images of ATO @ mesoporous silica nano microspheres in a cracked state and (b) ITO @ mesoporous silica nano microspheres in an intact state; and (c) Transmission Electron Microscope (TEM) images of ATO @ mesoporous silica nanospheres in the intact state and (d) ITO @ mesoporous silica nanospheres in the intact state.

FIG. 4 shows a flow diagram for preparing a coating composition according to one embodiment of the present invention.

FIG. 5 shows 3mm uncoated glass and coated with coating compositions 1-3 prepared according to one embodiment of the present invention (coating composition 1 comprising nanoparticle ATO, coating composition 2 comprising nanoparticle ATO and ITO, coating composition 2 comprising nanoparticle ATO, ITO, and Cs, respectively _x WO ₃ The coating composition 3) of (a) has an ultraviolet-visible light transmittance curve and a near-infrared light transmittance curve of a 3mm insulating glass.

FIG. 6 shows UV-visible and near-IR transmittance curves for 3mm uncoated glass and 3mm insulating glass coated with coating compositions 4-5 (coating composition 4 including ATO @ mesoporous silica nanospheres, coating composition 5 including ITO @ mesoporous silica nanospheres, respectively) prepared according to an embodiment of the present invention.

FIG. 7 shows (a) a homemade simulated insulation test apparatus for testing an insulating glass made according to an embodiment of the present invention; and (b) temperature dependence of irradiation time for 3mm uncoated glass, (c) 3mm coated with coating composition 3, (d) 4 coated with coating composition, and (e) 3mm insulating glass coated with coating composition 5.

FIG. 8 shows the results of the barrier properties at 365nm for ultraviolet and 1400nm for near infrared wavelengths and the transmittance test in the 380-760nm region for visible light for 3mm insulating glass (a) uncoated glass, (b) coated with coating composition 3 and (c) coated with coating composition 5, respectively.

Detailed Description

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. It is to be understood that the following description is intended to illustrate the present invention by way of example only and is not intended to limit the scope of the invention, which is defined by the appended claims. Also, it is understood by those skilled in the art that modifications may be made to the technical aspects of the present invention without departing from the spirit and gist of the present invention. Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the subject matter of this invention belongs. Before describing the present invention in detail, the following definitions are provided to better understand the present invention.

Where numerical ranges are provided, such as concentration ranges, percentage ranges, or ratio ranges, it is understood that each intervening value, to the tenth of the unit of the lower limit unless the context clearly dictates otherwise, between the upper and lower limit of that range and any other stated or intervening value in that stated range is encompassed within the subject matter. The upper and lower limits of these smaller ranges may independently be included in the smaller ranges, and such embodiments are also encompassed within the subject matter, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in the subject matter.

In the context of the present invention, many embodiments use the expressions "comprise", "include" or "consist essentially/essentially of \8230; \8230. The expressions "comprising", "including" or "consisting essentially of (8230); 8230%" generally are to be understood as open-ended expressions that include not only the elements, components, assemblies, method steps, etc. specifically listed below in the expression, but also other elements, components, assemblies, method steps. In addition, in this document, the expressions "comprising", "including" or "consisting essentially of/8230; \8230;" 8230 ";" consisting of "may also be understood in some cases as a closed expression, meaning that it includes only the elements, components, assemblies, method steps specifically listed after the expression, and does not include any other elements, components, assemblies, method steps. At this time, the expression is equivalent to the expression "consisting of 8230 \8230;.

For a better understanding of the present teachings and without limiting the scope of the present teachings, unless otherwise indicated, all numbers expressing quantities, percentages, or proportions, and other numerical values used in the specification and claims are to be understood as being modified in all instances by the term "about. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained. At the very least, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

In a first aspect of the invention, there is provided a nanosphere having a hollow core-shell structure comprising an outer shell formed of silica nanoparticles and an inner shell formed of first plasma nanoparticles.

In a specific embodiment, the silica nanoparticles are mesoporous silica nanoparticles.

In the context of the present invention, the term "plasmonic nanoparticles" refers to metal-containing nanoparticles capable of localized surface plasmon resonance. When sunlight is incident on the nano particles, if the frequency of incident photons is close to the electronic vibration frequency of the metal particles, the phenomenon of local surface plasmon resonance can occur. At this point, the metal nanoparticles have a strong interaction with photons of that frequency, exhibiting selective blocking (absorption or reflection) of spectrally specific wavelength energy. The resonance wavelength of the nanoparticles depends on the composition, shape, structure, size, etc. of the nanoparticles, and thus it is possible to prepare plasmonic nanoparticles that meet the target performance by varying experimental parameters.

In the context of the present invention, the term "mesoporous" refers to pores having a pore size of 2nm to 50 nm.

In the context of the present invention, the expressions "first" and "second" of "first plasmonic nanoparticle" and "second plasmonic nanoparticle" are used for the purpose of distinction only and are not intended to limit any order, rank or importance.

In yet another specific embodiment, the first plasma nanoparticles are Indium Tin Oxide (ITO), antimony Tin Oxide (ATO), lanthanum hexaboride (LaB) ₆ ) Cesium tungsten bronze (Cs) _x WO ₃ )(0＜x＜0.33)。

In a preferred embodiment, the first plasmonic nanoparticle is Indium Tin Oxide (ITO).

In yet another specific embodiment, the nanovesicles may have a size of 100nm to 500nm.

In a preferred embodiment, the nanovesicles may have a size of 450 nm.

In yet another specific embodiment, the shell may have a thickness of 10nm to 20nm.

In a preferred embodiment, the thickness of the shell may be 15 nm.

In yet another specific embodiment, the thickness of the inner shell may be 15 nanometers to 30 nanometers.

In a preferred embodiment, the thickness of the inner shell may be 20nm.

2) Secondary coating step: coating the matrix @ plasma nanoparticle core-shell microspheres with silicon dioxide nanoparticles to form matrix @ plasma nanoparticles @ silicon dioxide nanoparticle core-shell microspheres;

3) And (3) calcining: calcining at 400-600 deg.c to eliminate matrix microballoon and obtain nanometer microballoon with hollow core-shell structure.

In a specific embodiment, the primary coating step comprises: taking a substrate microsphere as a template, and coating the substrate microsphere with plasma nano-particles by using a plasma metal salt precursor through a sol-gel method. Here, the solvent-gel method is a common method for preparing molecular to nano-substructure materials well known in the art.

In a further specific embodiment, the matrix microspheres may be polymeric microspheres, such as polystyrene microspheres, polyethylene microspheres, polypropylene microspheres, poly terephthalic acid microspheres, but are not limited thereto.

In a still further specific embodiment, the size of the matrix microspheres is from 20nm to 200nm, preferably 100 nm. By selecting matrix microspheres (such as polystyrene microspheres) with different particle sizes as a template agent, the size-controllable nano-microspheres with hollow core-shell structures can be prepared by a sol-gel method.

In yet another specific embodiment, the plasma metal salt precursor is a halide salt, nitrate salt, or combination thereof of a plasma metal. One skilled in the art will be able to select a suitable plasmonic metal salt precursor depending on the plasmonic nanoparticles that are desired to be produced. For example, when the first plasma nanoparticles are ATO, the plasma metal salt precursor for preparing the same may be SnCl ₂ Or a hydrate thereof and SbCl ₃ Or a hydrate thereof. When the first plasma nanoparticles are ITO, the plasma metal salt precursor for preparing the same may be In (NO) ₃ ) ₃ Or a hydrate thereof and SnCl ₄ Or a hydrate thereof.

After the primary coating step is completed, the size of the matrix @ plasma nanoparticle core-shell microspheres is 40 nm to 300 nm.

In yet another specific embodiment, the primary coating step is carried out at a pH of 7 to 13. In a preferred embodiment, the primary coating step is carried out at a pH of 10. In this step, the pH value can be adjusted by ammonia, sodium hydroxide, or the like.

In yet another specific embodiment, the secondary coating step comprises: and carrying out secondary coating on the substrate @ plasma nanoparticle core-shell microspheres by using tetraethyl orthosilicate through a sol-gel method by using hexadecyl trimethyl ammonium bromide or P123 as a template agent to form the substrate @ plasma nanoparticle @ silicon dioxide nanoparticle core-shell microspheres. P123 is a polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer.

After the secondary coating step is completed, the thickness of the silica nanoparticle layer in the matrix @ plasma nanoparticles @ silica nanoparticle core-shell microspheres is 10 to 20 nanometers.

In a preferred embodiment, the templating agent is removed by calcination in the calcination step.

In yet another specific embodiment, the secondary coating step is carried out at a pH of 7 to 10. In a preferred embodiment, the preferred secondary coating step is carried out at pH 8. In this step, the pH can be adjusted by adding a certain proportion of ammonia, sodium hydroxide, etc.

In yet another specific embodiment, the temperature suitable for the calcination step may be selected based on the matrix microspheres, for example for polystyrene microspheres, preferably calcination is performed at a temperature of 500 ℃.

In a third aspect, the present invention provides a coating composition consisting of, based on the total weight of the coating composition:

(A) 50 to 75 weight percent of a water-borne resin;

(C) 4 to 15% by weight of auxiliaries.

In a specific embodiment, the aqueous resin is selected from at least one of an aqueous acrylic resin, a silicone-modified acrylic resin, an aqueous urethane resin, and a fluorocarbon resin. The aqueous resin plays an important role in the film forming capability, flexibility, adhesion and the like of the coating.

In a preferred embodiment, the aqueous acrylic resin is an aqueous acrylic resin having a solid content of 20 to 60% by weight.

In yet another preferred embodiment, the silicone-modified acrylic resin is a silicone-modified acrylic resin having a solids content of 50 to 70% by weight.

In yet another preferred embodiment, the aqueous polyurethane resin is an aqueous polyurethane resin having a solid content of 30 to 50% by weight.

In yet another preferred embodiment, the fluorocarbon resin is a fluorocarbon resin having a solid content of 45 to 55% by weight.

In a more preferred embodiment, the fluorocarbon resin is a fluorocarbon resin having a fluorine content of 20 to 30 wt%.

In a specific embodiment, the second plasma nanoparticles are selected from Indium Tin Oxide (ITO), antimony Tin Oxide (ATO), vanadium dioxide (VO) ₂ ) Vanadium pentoxide (V) ₂ O ₅ )、Cs _x WO ₃ (x is more than 0 and less than 0.33), titanium dioxide (TiO) ₂ )、La _x Eu _1-x B ₆ (x is more than 0 and less than 1). The present invention enables the coating composition of the present invention to achieve effective absorption of selected near infrared wavelengths by selecting metal nanoparticles capable of supporting surface plasmon resonance. This resonance is the coherent oscillation of surface conduction electrons excited by electromagnetic radiation, by which photons of near-infrared light interact with particles much smaller than the incident wavelength, creating a plasma that oscillates around the nanoparticle, with light absorption or reflection.

For the combination of at least two second plasma nanoparticles, it may be, for example, a combination of ITO and ATO, ITO, cs _x WO ₃ And ATO, and the like, but are not limited thereto. By combining the resonance bands of different plasma nanoparticles, full blocking of certain light wavelengths is achieved. FIG. 1 shows plasma nanoparticles ATO, ITO, and Cs _x WO ₃ Transmission spectrum curve in the visible near infrared range. As can be seen from FIG. 1, cs _x WO ₃ The transmission peak in the visible region is narrow, but the transmission gradually increases in the infrared region > 2000 nm. Whereas ITO has a broad transmission peak in the range of 500nm to 1500nm, the transmission is very low in the infrared region > 1500 nm.

In the context of the present invention, the terms "transmittance" and "transmittance" are used interchangeably and are used to characterize the degree of emergence of incident light after refraction through an object. Accordingly, the phrase "visible light transmittance" or "visible light transmittance" as used herein characterizes the light transmission properties of an object in terms of the ratio of the luminous flux of visible light after transmission to the incident luminous flux.

In yet another specific embodiment, the second plasmonic nanoparticle has a particle size in a range of 100nm to 400nm.

When the nano-microsphere with the hollow core-shell structure is used for the coating composition, the nano-microsphere adopts mesoporous SiO with low heat conductivity coefficient ₂ As a heat-resistant shell material, the heat transfer between the plasma nanoparticles and base materials such as films and glass in the hollow core-shell structure can be slowed down, and the formed shell/hollow structure is favorable for reflecting more sunlight through multiple interfaces. Therefore, compared with the combination of the plasma nano particles, the nano microspheres with the hollow core-shell structure are obtained by performing surface modification on the plasma nano particles, so that not only are the original optical properties of the plasma nano particles retained, but also the blocking effect on sunlight, especially near infrared light in the sunlight is remarkably improved.

In yet another specific embodiment, the nanoparticle slurry is a mixture of the nanospheres or the combination of the at least two second plasmonic nanoparticles dispersed in water, such as deionized water, containing a dispersing agent and a pH adjusting agent.

In a preferred embodiment, the total weight of the nanospheres or the second plasmonic nanoparticles is 20 to 40 wt% of the total weight of the nanoparticle slurry.

In yet another specific embodiment, the dispersing agent is selected from polyvinylpyrrolidone, polyethylene glycol, or a combination thereof. The dispersant is used to bridge the space between the nanoparticles.

In yet another specific embodiment, the dispersant is 1 to 3 wt% of the total weight of the nanoparticle slurry.

In yet another specific embodiment, the pH adjusting agent may be selected from hydrochloric acid or ammonia solution for increasing particle stability such that the pH value of the nanoparticle slurry is 7 to 8.

In a preferred embodiment, the pH adjusting agent is 0.1 to 0.5 wt% of the total weight of the nanoparticle slurry.

In yet another specific embodiment, the auxiliary agents may include ultraviolet absorbers, leveling agents, defoaming agents, and film forming agents.

In a preferred embodiment, the uv absorber may be a compound including phenyl and/or C = N groups to block uv light and retard photo-oxidation of the coating compound. One skilled in the art will appreciate that most plasmonic nanoparticles employed in the present invention do not have the ability to absorb ultraviolet light and that the coating composition of the present invention blocks substantially all ultraviolet light, e.g., at least 98% of the ultraviolet light, by the addition of an ultraviolet absorber thereto.

In a more preferred embodiment, the ultraviolet absorber may be at least one selected from the group consisting of benzophenone, benzotriazole, triazine, salicylate, and organic substances. The conjugated pi-electron structure in the uv absorber accounts for the ability of the material to absorb uv light. For example, the ultraviolet absorber may contain a hydroxyl group at a position adjacent to the hydroxyl group, and the hydroxyl group may form a chelate ring with nitrogen or oxygen. Under the action of illumination, the energy absorbed by opening the chelate ring is just similar to that of ultraviolet light with the wave band of 290nm to 400nm, so that the aim of absorbing the ultraviolet light can be fulfilled.

Thus, in a more specific embodiment, the uv absorber is one or more selected from the group consisting of bis (1, 2, 6-pentamethyl-4-piperidinyl) -sebacic acid ester of the following formula (I), benzotriazole of the following formula (II), 2-hydroxy-4-methoxybenzophenone of the following formula (III), and N- (ethoxycarbonylphenyl) -N' -methyl-phenylformamidine of the following formula (IV).

In yet another preferred embodiment, the leveling agent may be selected from at least one of acrylate copolymers and non-reactive polyether modified polysiloxanes for eliminating various possible defects of the coating material occurring during application.

In yet another preferred embodiment, the defoaming agent may be selected from at least one of polysiloxane-polyether copolymer, octanol, tributyl phosphate, triphenyl phosphate, and emulsified methyl siloxane for eliminating bubbles generated during the preparation of the coating material.

In yet another preferred embodiment, the film former may be selected from at least one of glycol ether solvents, glycol ester solvents, and dipropylene glycol butyl ether for facilitating film formation and preventing cracking and breakage of the dried coating during curing.

In a more preferred embodiment, the ultraviolet absorber, the leveling agent, the defoaming agent, and the film-forming agent may be in an amount of 1 to 10 wt%, 0.01 to 1 wt%, and 0.5 to 3 wt%, respectively, based on the total weight of the coating composition.

By using surface-modified plasmonic nanoparticles or a combination of specific types of plasmonic nanoparticles in the coating composition of the present invention, not only light in the near infrared region wavelength range can be selectively absorbed for thermal insulation, while maintaining the visible light transmittance of the coating, thereby ultimately imparting excellent thermal insulation properties to architectural windows and curtain walls.

In a fourth aspect, there is provided a thermal insulation element comprising a transparent substrate and the coating composition of the third aspect applied to a surface of the transparent substrate.

In a particular embodiment, the insulation is transparent.

In a preferred embodiment, the thermal insulation has a visible light transmittance of not less than 70%.

In a specific embodiment, the coating composition applied to the surface of the transparent substrate has a thickness of 10 to 15 microns.

In a specific embodiment, the thermal shield absorbs at least 98% of the ultraviolet light.

In a preferred embodiment, the thermal insulation absorbs at least 99% of the ultraviolet light.

In a specific embodiment, the thermal insulation absorbs at least 70% of the near infrared light.

In a further specific embodiment, the thermal insulation absorbs at least 80% of the near infrared light.

In a further specific embodiment, the thermal shield absorbs about 90% of the near infrared light.

In yet another embodiment, the transparent substrate is glass. The heat insulation coating coated on the surface of the heat insulation glass prepared by the method can absorb not less than 98 percent, even not less than 99 percent of ultraviolet light and not less than 70 percent, even 90 percent of near infrared light in solar spectrum, effectively shield heat, further effectively maintain indoor temperature, obstruct or reduce the influence of environmental temperature, and realize the indoor and outdoor temperature difference of a building of 8 ℃ to 10 ℃. At the same time, the insulating glass has at least 70% visible light transmittance, and thus has the potential to be applied to building windows and curtain walls, thereby providing an ideal potential candidate material for building energy conservation.

As described above, the thermal insulation member selectively blocks/absorbs near infrared light in the solar spectrum mainly by the nano microspheres having a hollow core-shell structure or the combination of at least two kinds of plasmonic nanoparticles in the coating composition of the present invention coated on the surface of the transparent substrate. The insulation of the present invention can be manufactured at a low cost through a simple process well known to those skilled in the art. For example, the coating composition of the present invention can be applied to a large area substrate such as a glass substrate by a conventional coating process, and after curing, a uniform thermal barrier coating having a thickness of 10 to 15 μm is formed, which has a long service life, good stability, and is easy to maintain, thereby obtaining economic and social benefits due to the synergistic effect of the coating composition.

(1) Preparing nanoparticle slurry, wherein at least one plasma nanoparticle, a dispersing agent and a pH regulator are dispersed in deionized water, and the nanoparticle slurry is formed through stirring, ball milling and ultrasonic treatment;

It is noted that in the process of preparing the coating composition, it is necessary to avoid directly mixing the undispersed nanoparticles with the aqueous resin, and since the dispersibility of the nanoparticle slurry greatly affects the overall performance of the final coating composition, the nanoparticles must be prepared into a uniformly dispersed slurry before being mixed with the resin and the additives to prepare the coating.

The order of addition of the various adjuvants is not critical to the coating composition of the invention, but it is necessary to have sufficient mechanical agitation time after the addition of each adjuvant to ensure uniform mixing. The above-described preparation method of the present invention is a method for preparing a coating material having good dispersibility and uniformity, which is well known in the art.

Examples

In the following examples, the inventors prepared coating compositions comprising nanospheres with a hollow core-shell structure and coating compositions comprising one, two and three kinds of plasmonic nanoparticles, respectively, and examined their associated thermal insulation properties as glass coatings.

Unless otherwise specified, the test methods employed therein were all conventional methods, and, unless otherwise specified, the test materials used in the following examples were all purchased from a conventional reagent store. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

It should be noted that the terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The foregoing summary of the invention, as well as the following detailed description, is intended to be illustrative of the invention only and is not intended to be in any way limiting. The scope of the invention is to be determined by the appended claims without departing from the spirit and scope of the invention.

Example 1: preparation and optical performance characterization of ATO @ mesoporous nano-silica

Referring to fig. 2, an exemplary preparation process of ato @ mesoporous nano silica having a hollow structure is as follows:

1. preparation of polystyrene @ ATO microspheres

Weighing 10 g of polystyrene spheres, 9 g of ammonia water and 100 ml of ethanol, adding the polystyrene spheres, the ammonia water and the ethanol into a three-neck flask, and adding SnCl containing plasma metal salt precursor liquid ₂ ·2H ₂ O and SbCl ₃ The mixture of ethanol and catalyst was added dropwise to a three-necked flask and allowed to react at 80 ℃ for 6 hours. And after the reaction system is cooled to room temperature, centrifuging the obtained microspheres, washing with ethanol for three times, drying at 60 ℃ for 12 hours to obtain polystyrene @ ATO microspheres, collecting and standing for the next reaction.

2. Preparation of polystyrene @ ATO @ nano-silica microspheres

Ultrasonically dispersing 10 g of polystyrene @ plasma particle microspheres obtained in the first step into a mixed solution of 40 ml of isopropanol and 10 ml of deionized water, and adding ammonia water in a certain proportion to adjust the pH value of the mixed solution to 8.0. Then 0.1 g of hexadecyl trimethyl ammonium bromide is added, 1 ml of tetraethyl orthosilicate is added after stirring and dissolving at 25 ℃, and the reaction is stopped after reacting for 3 hours. And drying the sample at 120 ℃ to obtain the polystyrene @ ATO @ nano silicon dioxide microsphere.

3. Preparation of ATO @ mesoporous nano-silica hollow core-shell structure microsphere

And placing the powder in a muffle furnace and calcining at 500 ℃ to remove the polystyrene and hexadecyl trimethyl ammonium bromide template agent, thus obtaining the ATO @ mesoporous nano-silica hollow core-shell structure microsphere.

4. And (3) carrying out structural characterization on the ATO @ mesoporous nano-silica hollow core-shell structure microspheres obtained in the step (3).

Fig. 3 (a) shows the ato @ mesoporous silica nanospheres in a ruptured state (for the purpose of explaining the internal structure of the nanospheres), it can be observed that the shell thickness of the ato @ mesoporous silica hollow core-shell microsphere prepared by the above method is clearly visible with naked eyes, and the surface of the shell material is rough and covered by mesoporous spherical particles of different sizes. From FIG. 3 (c), it can be observed that the structure of the ATO @ mesoporous nano silica hollow core-shell structure microsphere prepared by the above method is in a hollow state, and the core-shell structure is clear.

Example 2: preparation and optical performance characterization of ITO @ mesoporous nano silica

Referring also to FIG. 2, an exemplary preparation flow of ITO @ mesoporous nano-silica of hollow structure is as follows:

1. preparation of polystyrene @ ITO microspheres

10 g of polystyrene spheres, 9 g of ammonia water and 100 ml of ethanol are weighed into a three-neck flask, and precursor liquid In (NO) containing plasma metal salt is added ₃ ) ₃ ·5H ₂ O and SnCl ₄ ·5H ₂ A mixture of O, ethanol and catalyst was added dropwise to a three-necked flask and allowed to react at 80 ℃ for 6 hours. After the reaction system is cooled to room temperature, centrifuging the obtained microspheres, washing with ethanol for three times, drying at 60 ℃ for 12 hours to obtain polystyrene @ ITO microspheres, collecting and standing for the next reaction.

2. Preparation of polystyrene @ ITO @ nano silicon dioxide microspheres

Ultrasonically dispersing 10 g of polystyrene @ ITO microspheres obtained in the first step into a mixed solution of 80 ml of isopropanol and 10 ml of deionized water, and adding ammonia water in a certain proportion to adjust the pH value to 8.0. Then 0.1 g of hexadecyl trimethyl ammonium bromide is added, 1 ml of tetraethyl orthosilicate is added after stirring and dissolving at 25 ℃, and the reaction is stopped after 3 hours of reaction. And drying the sample at 120 ℃ to obtain the polystyrene @ ITO @ nano silicon dioxide microsphere.

3. Preparation of ITO @ mesoporous nano-silica hollow core-shell structure microsphere

And placing the powder in a muffle furnace and calcining at 500 ℃ to remove the polystyrene and hexadecyl trimethyl ammonium bromide template agent, thus obtaining the ITO @ mesoporous nano silicon dioxide hollow core-shell structure microsphere.

4. And (3) carrying out structural characterization on the ITO @ mesoporous nano silica hollow core-shell structure microspheres obtained in the step (3) to obtain an SEM spectrogram shown in a figure (b) and a TEM spectrogram shown in a figure (d).

It can be observed from fig. 3 (b) that the morphology of the ito @ mesoporous nano silica hollow core-shell structure microsphere prepared by the above method is in a complete spherical shape, the surface of the shell material is rough, and the shell material is covered by spherical particles with different sizes and mesoporous shapes. It can be observed from fig. 3 (d) that the structure of the hollow core-shell structure microsphere of ito @ mesoporous nano silica is in a hollow form, and the core-shell structure is clear.

Example 3: preparation of the coating composition

With reference to the process flow given in fig. 4, exemplary coating compositions 1-5 of the present invention were prepared according to the concentrations and volumes of the individual components given in table 1 below.

First, from step 101, nanoparticles (or a combination of plasma nanoparticles) having a hollow core-shell structure, a dispersant, a pH adjuster, and deionized water are mixed and stirred for 30 minutes to 1 hour to form a mixed suspension.

Then, in step 102, the well-mixed suspension is dispersed by milling the suspension at a speed of 500rpm for 24 hours and sonicating at an amplitude of 25% for 30 minutes, forming a well-dispersed nanoparticle slurry.

Next, in step 103, the well-dispersed nanoparticle slurry is added to the aqueous resin, and then sufficiently mixed at a speed of 600rpm to form an initial thermal barrier coating.

Finally, in step 104, a coating adjuvant is added and mixed with the initial thermal barrier coating at a rate of 1000 rpm to form a final transparent thermal barrier coating that can be applied to the surface of the glass substrate.

Example 4: visible light transmittance of coating composition

The coating compositions 1 to 5 prepared in example 3 were applied to the surface of a glass substrate to form a coating layer having a thickness of about 10 to 15 μm, to give corresponding heat insulating glasses 1 to 5.

The insulation glass was subjected to ultraviolet-visible-near infrared (UV-Vis-NIR) transmission spectroscopy by hitachi UH 4150. The wavelength range of the visible-near infrared (Vis-NIR) spectrophotometer was 200nm to 2600nm using an integrating sphere detection mechanism, and the results are shown in fig. 5 and 6.

As can be seen from fig. 5, the glass inner surface coating has a visible light transmittance of not less than 60% regardless of whether it includes only one kind of nanoparticles or two or three kinds of nanoparticles. However, coating composition 1, which includes only one type of ATO nanoparticles, still has a short transmission peak in the infrared spectrum range of 800-2600nm, while coating

compositions

2 and 3, which include two or three types of nanoparticles, have only 40% infrared transmittance, showing a weak blocking capability against the near infrared spectrum.

As can be seen from fig. 6, the uv-visible and nir transmission spectra of 3mm insulating glass coated with the coating composition 4 prepared in example 3 (coating composition including ato @ mesoporous silica nanospheres) showed at least 98% blocking rate in the uv band of 200-400nm, at least 70% transmittance in the visible band of 400-800nm, and at least 80% blocking rate in the nir band greater than 1200 nm; the ultraviolet-visible light and near-infrared transmission spectra of 3mm heat-insulating glass coated with the coating composition 5 prepared in example 3 (coating composition including ito @ mesoporous silica nanospheres) showed at least 98% blocking rate in the ultraviolet wavelength band of 200-400nm, at least 70% transmittance in the visible wavelength band of 400-800nm, and at least 90% blocking rate in the near-infrared wavelength band greater than 1000nm, both of which showed strong blocking ability to the near-infrared spectrum.

Example 5: heat insulating properties of coating compositions

The insulating properties of the insulating glass 3-5 prepared in example 4 of the present invention were investigated by a homemade testing apparatus. As shown in fig. 7a, the test apparatus consisted of a 250W infrared lamp (wavelength range 760nm to 3000 nm), an insulated chamber with two windows covered by replaceable glass, and a temperature data logger. The inside and outside temperature differences of the heat-insulating chamber of the uncoated glass of 3mm and the heat-insulating glasses 3 to 5 produced in example 4 were measured, respectively, and the results are shown in FIGS. 7 (b) to 7 (e). Meanwhile, the uv-visible light and nir blocking ratio tests were performed on the uncoated insulating glass and the insulating

glasses

3 and 5 manufactured in example 4 using an LS182 solar film tester, and the results are shown in fig. 8.

As shown in fig. 7 (b) and 7 (c), for the thermal chamber (fig. 7 (b)) without coated glass (ordinary glass), the temperature in the test chamber (3) is higher than the temperature of the ordinary glass face (1) (outside the test chamber) and the ordinary glass face (2) (inside the test chamber), so that the temperature in the test chamber (3) is at its highest, about 42 ℃. For the insulating glass with coating composition 3 (fig. 7 (c)), the temperature inside the test chamber (3) with the ordinary glass installed is much lower than inside (5) and outside (4) the surface of the insulating glass. And the difference between the temperature in the heat insulation cavity of the heat insulation glass and the temperature in the heat insulation chamber of the uncoated glass is about 5 ℃ by comparison, which proves that when the coating composition 3 provided by the invention is coated on the surface of the glass, the excellent heat insulation performance can be shown, the indoor temperature can be effectively maintained, and the influence of the environmental temperature can be blocked or reduced, but the temperature of the coating is too high, which means that the risk of degrading the coating can exist in the long-term use of the heat insulation glass, so that the service life of the coating is influenced.

As shown in fig. 7 (d) and 7 (e), for the insulated glass chamber coated with the coating composition 4 (fig. 7 (d)), the temperature inside the test chamber (3) with the ordinary glass installed approaches the temperature of the coated glass side (4) (outside the test chamber) and the ordinary glass side (5) (inside the test chamber), and the comparison shows that the temperature inside the insulated chamber with the insulated glass is about 6 ℃ different from the temperature inside the insulated chamber with no coated glass; for the insulating glass coated with coating composition 5 (fig. 7 (e)), the temperature inside (5) and outside (4) the surface of the insulating glass was lower than the temperature inside (3) the test chamber with the ordinary glass installed, and the difference between the temperature inside the insulating chamber of the insulating glass and the temperature inside the insulating chamber with uncoated glass was found to be about 8.5 ℃. The data prove that when the coating compositions 4 to 5 are coated on the surface of glass, the coating not only can show excellent heat insulation performance, but also has good heat dissipation performance, so that the service life of the heat insulation glass is greatly prolonged, and the excellent market application potential is shown.

As shown in FIGS. 8 (a) to 8 (c), the ordinary uncoated glass (FIG. 8 (a)) having a thickness of 3mm has a blocking rate of 14.4% at a wavelength of 365nm of ultraviolet light, a transmittance of 88.9% at a wavelength of 400 to 800nm of visible light, and a blocking rate of 17.7% at a wavelength of near infrared of 1400 nm. The 3mm heat insulating glass coated with the coating composition 3 prepared in example 3 (fig. 8 (b)) had a blocking rate of 96.9% at an ultraviolet wavelength of 365nm, a transmittance of 79.9% at a visible light band of 400-800nm, and a blocking rate of 84.2% at a near infrared wavelength of 1400nm, compared to 3mm uncoated glass. However, 3mm insulating glass (fig. 8 (c)) coated with coating composition 5 prepared in example 3 (coating composition including ito @ mesoporous silica nanospheres) had 98.4% blocking rate at 365nm of ultraviolet wavelength, 78.1% transmittance at 400-800nm of visible wavelength, and 93.8% blocking rate at 1400nm of near infrared wavelength, which is the most preferable choice for all coating compositions.

Claims

1. A nanosphere having a hollow core-shell structure comprising an outer shell formed from a silica nanoparticle and an inner shell formed from a first plasmonic nanoparticle.

2. The nanosphere of claim 1, wherein said silica nanoparticle is a mesoporous silica nanoparticle.

3. The nanovesicles of claim 1 or 2, wherein the first plasmonic nanoparticle is Indium Tin Oxide (ITO), antimony Tin Oxide (ATO), lanthanum hexaboride (LaB) ₆ ) Cesium tungsten bronze (Cs) _x WO ₃ )(0<x<0.33 Indium Tin Oxide (ITO) is preferred.

4. Nanovesicles according to any one of claims 1 to 3 wherein the nanovesicles have a size of 100 to 500nm, preferably 450 nm; the thickness of the shell is 10 to 20 nanometers, preferably 15 nanometers; the thickness of the inner shell is 15 nm to 30 nm, preferably 20nm.

5. A method of preparing the nanospheres of any of claims 1-4 comprising:

3) And (3) calcining: calcining at 400-600 deg.C, preferably 500 deg.C to remove the matrix microsphere and obtain the nano microsphere with hollow core-shell structure.

6. The method of claim 5, wherein the primary coating step comprises: coating plasma nanoparticles on a substrate microsphere (e.g., a polymer microsphere such as a polystyrene microsphere, a polyethylene microsphere, a polypropylene microsphere, or a poly (terephthalic acid) microsphere) by a sol-gel method using a plasma metal salt precursor; the plasma metal salt precursor is, for example, a halide salt, a nitrate salt, or a combination thereof of a plasma metal.

7. The method of claim 5 or 6, wherein the secondary coating step comprises: taking hexadecyl trimethyl ammonium bromide or P123 as a template agent, and carrying out secondary coating on the matrix @ plasma nanoparticle core-shell microspheres by using tetraethyl orthosilicate through a sol-gel method to form the matrix @ plasma nanoparticle @ silicon dioxide nanoparticle core-shell microspheres; preferably, the templating agent is removed by calcination in the calcination step.

8. The process according to any one of claims 5 to 7, wherein the primary coating step is carried out at a pH of from 7 to 13, preferably at a pH of 10; the secondary coating step is carried out at a pH of 7 to 10, preferably at a pH of 8.

9. The method of any one of claims 5-8, wherein the matrix microspheres are 20nm to 200nm in size, preferably 100 nm.

10. A coating composition consisting of, based on the total weight of the coating composition:

(A) 50 to 75 weight percent of a water-borne resin;

(B) 11 to 35 wt% of a nanoparticle slurry comprising the nanospheres of any of claims 1-4 or the nanospheres prepared by the method of any of claims 5-9 or a combination comprising at least two second plasmonic nanoparticles; and

(C) 4 to 15% by weight of an auxiliary.

11. The coating composition of claim 10, wherein the second plasma nanoparticles are selected from Indium Tin Oxide (ITO), antimony Tin Oxide (ATO), vanadium dioxide (VO) ₂ ) Vanadium pentoxide (V) ₂ O ₅ )、Cs _x WO ₃ (0<x<0.33)、La _x Eu _1-x B ₆ (0<x<1)。

12. The coating composition of claim 10 or 11, wherein the second plasmonic nanoparticle has a particle size in the range of 100nm to 400nm.

13. The coating composition of any one of claims 10-12, wherein the nanoparticle slurry is a mixture of the nanospheres or the combination of the at least two second plasmonic nanoparticles dispersed in water containing a dispersant and a pH modifier; and preferably the total weight of the nanosphere or the combination of the at least two second plasmonic nanoparticles is 20 wt% to 40 wt% of the total weight of the nanoparticle slurry.

14. The coating composition according to any one of claims 10 to 13, wherein the aqueous resin is at least one selected from the group consisting of an aqueous acrylic resin, a silicone-modified acrylic resin, an aqueous urethane resin, and a fluorocarbon resin;

preferably, the aqueous acrylic resin is an aqueous acrylic resin with a solid content of 20 to 60 wt%;

preferably, the organic silicon modified acrylic resin has a solid content of 50 to 70 wt%;

preferably, the aqueous polyurethane resin has a solid content of 30 to 50 wt%; and

preferably, the fluorocarbon resin is a fluorocarbon resin with a solid content of 45 to 55 wt%; more preferably, the fluorocarbon resin is a fluorocarbon resin having a fluorine content of 20 to 30 wt%.

15. The coating composition of claim 13, wherein the dispersant is selected from polyvinylpyrrolidone, polyethylene glycol, or a combination thereof, and preferably the dispersant is 1 to 3 wt% of the total weight of the nanoparticle slurry.

16. The coating composition according to claim 13, wherein the pH adjusting agent is selected from hydrochloric acid or ammonia solution, and preferably the pH adjusting agent is 0.1 to 0.5 wt% of the total weight of the nanoparticle slurry.

17. The coating composition of any one of claims 10-16, wherein the nanoparticle slurry has a pH of 7 to 8.

18. The coating composition according to claims 10-17, wherein the auxiliary agent comprises a uv absorber, a leveling agent, a defoamer and/or a film former;

preferably, the ultraviolet absorber is a compound comprising phenyl and/or C = N groups, preferably at least one selected from organic compounds of the benzophenone type, benzotriazole type, triazine type, salicylate type;

preferably, the leveling agent is at least one selected from acrylate copolymers and non-reactive polyether modified polysiloxanes;

preferably, the defoaming agent is selected from at least one of polysiloxane-polyether copolymer, octanol, tributyl phosphate, triphenyl phosphate, and emulsified methyl siloxane;

preferably, the film former is selected from at least one of a glycol ether solvent, a glycol ester solvent, and dipropylene glycol butyl ether;

more preferably, the amounts of the ultraviolet absorber, the leveling agent, the defoamer, and the film-forming agent are 1 to 10 wt%, 0.01 to 1 wt%, and 0.5 to 3 wt%, respectively, based on the total weight of the coating composition.

19. An insulation element comprising a transparent substrate and a coating composition according to any one of claims 10-18 applied to the surface of the transparent substrate, such as glass.

20. A thermal insulating element according to claim 19, wherein the element is transparent, preferably the thermal barrier coating has a visible light transmission of not less than 70%.

21. A thermal insulating element according to claim 19 or 20, wherein the coating composition applied to the surface of the transparent substrate has a thickness of 10 to 15 microns.

22. A thermal insulation element according to any of claims 19-21, wherein the thermal insulation element absorbs at least 70% of the near infrared light, such as about 80% of the near infrared light, even at least 90% of the near infrared light; and the insulation absorbs at least 98% of the ultraviolet light, preferably at least 99% of the ultraviolet light.

23. A method of making the coating composition of any one of claims 19-22, comprising: