Method for manufacturing paints and structures

Abstract

To provide a coating that can form an anti-fouling layer on the surface of a transparent substrate without significantly reducing light transmittance. [Solution] The paint of the present disclosure contains 0.5% to 5% by mass of silicon compound particles that generate silicon oxide by curing the paint, 0.1% to 5% by mass of tin oxide particles, and further contains particles of at least one of indium oxide or aluminum oxide. If indium oxide is included, the indium oxide particles are contained in 1% to 20% by mass of the paint, and if aluminum oxide is included, the aluminum oxide particles are contained in 1% to 5% by mass of the paint.

Description

Technical Field

[0001] The present disclosure relates to paints and a method for manufacturing a structure.

Background Art

[0002] In view of environmental issues and resource conservation, it is desired to extend the lifespan of industrial products for waste reduction and resource conservation, and to reuse used products with improved performance. In glass products, performance may deteriorate due to breakage, dirt, cloudiness, etc. However, especially for dirt, cloudiness, etc., the performance can be restored to a state close to the initial state by cleaning, etc. at the installation site.

[0003] Functionalities such as the installation of a transparent electrode and the formation of a functional layer having antifouling properties can be imparted to a transparent substrate such as glass. However, for example, when installing a transparent electrode, a large-scale process such as vacuum evaporation is performed, so the apparatus tends to be large-sized. In addition, construction within a manufacturing facility is a prerequisite for imparting functionality, and construction on a transparent substrate that has already been installed is rarely carried out from the perspective of construction costs.

[0004] Patent Document 1 describes "a coating liquid for suppressing solar cell degradation, which is composed of an aqueous solution of a water-soluble compound of at least one metal selected from silicon, aluminum, zirconium, tin, and zinc or a fine particle dispersion of an oxide of the metal, and each of the aqueous solution and the fine particle dispersion contains 0.01 to 10% by mass of the compound or the oxide in terms of metal oxide, and the fine particle dispersion has fine particles with an average primary particle diameter of 50 nm or less dispersed with a dispersion particle diameter (D50) of less than 100 nm."

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] When a layer that provides stain resistance (stain-resistant layer) is formed on the surface of a transparent substrate, the light transmittance of the entire transparent substrate with the stain-resistant layer may be significantly lower compared to the light transmittance of the transparent substrate alone. The problem that this disclosure aims to solve is to provide a paint and a method for manufacturing a structure that can form an antifouling layer on the surface of a transparent substrate without significantly reducing the light transmittance. [Means for solving the problem]

[0007] The paint of this disclosure is a paint that contains 0.5% to 5% by mass of silicon compound particles that generate silicon oxide upon curing of the paint, 0.1% to 5% by mass of tin oxide particles, and further contains particles of at least one of indium oxide or aluminum oxide. If indium oxide is included, the indium oxide particles are contained in 1% to 20% by mass of the paint. If aluminum oxide is included, the aluminum oxide particles are contained in 1% to 5% by mass of the paint. Other solutions will be described later in the modes for carrying out the invention. [Effects of the Invention]

[0008] According to this disclosure, it is possible to provide a paint and a method for manufacturing a structure that can form an antifouling layer on the surface of a transparent substrate without significantly reducing the light transmittance. [Brief explanation of the drawing]

[0009] [Figure 1] This is a flowchart of the manufacturing method for the structure disclosed herein. [Figure 2] This is a schematic diagram of the structure disclosed herein. [Figure 3] This figure provides a detailed explanation of the layer structure of the coating film shown in Figure 2. [Figure 4A] This graph shows an example of the transmittance measurement results for glass substrates coated with the paints of this disclosure, specifically for compositions 2 to 4. [Figure 4B] This graph shows an example of the transmittance measurement results for glass substrates coated with the paints of this disclosure, specifically for compositions 5 to 7. [Figure 4C] This graph shows an example of the transmittance measurement results for glass substrates coated with the paints of this disclosure, specifically for compositions 8 to 11. [Figure 5A] This graph shows an example of reflectance measurement results for glass substrates coated with the paints of this disclosure, illustrating the results for compositions 2 to 6. [Figure 5B] This graph shows an example of reflectance measurement results for glass substrates coated with the paints of this disclosure, specifically for compositions 8-11. [Figure 6] This is a schematic diagram of a cross-section of a glass substrate provided in a solar panel, in which the paint of this disclosure has been applied. [Figure 7A] This is an example of output measurement results for a solar panel coated with the paint (composition 2) of this disclosure to form a coating film. [Figure 7B] This is an example of output measurement results for a solar panel to which a coating film has been formed by applying the paint (composition 3) of this disclosure. [Modes for carrying out the invention]

[0010] The following describes embodiments for implementing this disclosure, with reference to the drawings. The following is merely an example of how to implement the invention related to this disclosure, and this disclosure is not limited to the following example. Within the description of one embodiment below, other embodiments applicable to that embodiment will also be described as appropriate. This disclosure is not limited to the following embodiment, and different embodiments can be combined or modified as appropriate without significantly impairing the effects of this disclosure. In addition, the same reference numerals will be used for the same components, and redundant explanations will be omitted. Furthermore, components having the same function will be given the same name. The illustrations are schematic, and for illustrative purposes, the actual configuration may be changed or some components may be omitted or modified between drawings without significantly impairing the effects of this disclosure. Also, the same embodiment does not necessarily need to have all the components.

[0011] The coatings of this disclosure are coatings that can be applied to transparent substrates, such as glass substrate 1 (Figure 2). The coating film 20 (Figure 2) obtained by applying the coating of this disclosure to a transparent substrate and then drying it has predetermined functionality and high light transmittance (translucency). Therefore, any function can be imparted using the coating film 20 while maintaining at least the light transmittance of the transparent substrate, that is, without a significant decrease compared to the transmittance of the transparent substrate alone. "Not a significant decrease" here means, for example, having a transmittance of 98% or more, which is generally considered to be about the same as the light transmittance of the transparent substrate alone. The light referred to here includes, but is not limited to, infrared rays, visible light, ultraviolet rays, etc. The function referred to here is at least antifouling. Antifouling is the property of being able to suppress the adhesion of foreign matter such as sand and dust to the surface of the coating film 20 due to electrical forces on the surface of the coating film 20. Therefore, antifouling can be evaluated by measuring the electrical resistance (difficulty of electricity flow) of the coating film 20, for example, although the details will be described later in the examples. In addition to stain resistance, the function may also include, for example, water repellency, heat dissipation, cooling properties, hardness, etc. However, the function is not limited to these.

[0012] Furthermore, transparent substrates such as glass substrate 1 may experience a decrease in transmittance due to deterioration, for example. However, by using a paint with a predetermined composition from the paint composition of this disclosure to form a coating film 20 on a transparent substrate with reduced transmittance, it is possible to restore (improve) the transmittance, even if it is slightly lower than the transmittance of the transparent substrate alone. In addition, forming a coating film 20 on a transparent substrate that has not deteriorated can be expected to lead to the addition of additional performance and performance improvement.

[0013] The coatings of this disclosure contain silicon compounds and tin oxides. Furthermore, the coatings of this disclosure contain an oxide of at least one (or both) of indium oxide or aluminum oxide. Furthermore, the coatings of this disclosure contain other components as appropriate and any dispersion medium.

[0014] The silicon compound is a component that forms silicon oxide (e.g., silicon dioxide, SiO2, but not limited thereto) upon curing of the paint of the present disclosure. The silicon compound, tin oxide, indium oxide, aluminum oxide, and other appropriate components are, for example, dispersed in a dispersion medium, and thus the paint of the present disclosure usually has a slurry form.

[0015] The silicon compound serves as the backbone of the coating film 20 of the present disclosure formed by applying and drying (curing) the paint of the present disclosure, and is a compound that realizes a low refractive index (i.e., high transmittance) of the coating film 20. Specifically, silicon constituting the silicon compound forms a silicon backbone (i.e., silicon oxide) by bonding with oxygen in the environment, for example, to form a network of -Si-O- bonds, and the paint cures. Therefore, in the coating film 20, the silicon oxide does not exist in the form of particles. Specific examples of such a silicon compound include, but are not limited to, SiH2NH (perhydropolysilazane). SiH2NH reacts with moisture, hydrogen, etc. in the environment (atmosphere), for example, to cause a hydrolysis reaction and generate silica glass. At this time, ammonia and hydrogen are by-produced. The generated silica glass is solid, and in this case, the silica glass fixes (encapsulates) indium oxide, aluminum oxide, etc. within the coating film 20.

[0016] For example, if the above network pattern in the silica glass is too dense, the transmittance of the coating film 20 and the transparent substrate on which the coating film 20 is formed tends to decrease, and if the network pattern is too sparse, the strength of the coating film 20 tends to decrease. Therefore, in the paint, the silicon compound is contained at 0.5% by mass or more and 5% by mass or less, preferably 0.1% by mass or more and 5% by mass or less, based on the whole paint of the present disclosure. By containing it at this ratio, both high transmittance and high strength can be achieved.

[0017] The silicon compound is included in the paint of the present disclosure in the form of particles (not shown). Therefore, the paint of the present disclosure contains particles of the silicon compound. The size of the particles of the silicon compound is not particularly limited, but the particle size of the silicon compound is, for example, 1 nm or more and 50 nm or less, preferably 1 nm or more and 30 nm or less, more preferably 1 nm or more and 20 nm or less. By setting the particle size within this range, the transmittance of the coating film 20 and the transparent substrate on which the coating film 20 is formed can be increased. For example, the average particle size based on the laser diffraction scattering method can be adopted as the particle size.

[0018] The paint of the present disclosure contains tin oxide (for example, but not limited to, tin(II) oxide. SnO). By containing tin oxide, the surface resistance of the coating film 20 can be reduced to suppress electrostatic charging, and the adhesion of sand, dust, etc. can be suppressed. Thereby, the adhesion of foreign substances to the surface of the coating film 20 can be suppressed to impart antifouling properties, and the transmittance of the coating film 20 and the transparent substrate on which the coating film 20 is formed can be improved.

[0019] Tin oxide is contained in the paint of the present disclosure, for example, in an amount of 0.1% by mass or more and 5% by mass or less, preferably 0.5% by mass or more and 2% by mass or less, based on the whole paint. By containing it within this range, it is possible to make it difficult for foreign substances to adhere to the surface of the coating film 20.

[0020] Tin oxide is included in the paint of the present disclosure in the form of particles 11 (FIG. 2). Therefore, it is preferable that the paint of the present disclosure contains particles 11 of tin oxide. The size of the particles 11 is not particularly limited, but for example, the size within the numerical range described above for the particle size of the silicon compound (for example, 50 nm or less) can be applied. However, the particle size of tin oxide does not have to be the same as that of the silicon compound. Also, for example, the particle size measured based on the measurement method of the particle size of the silicon compound described above (average particle size) can be adopted as the particle size of tin oxide.

[0021] Indium oxide (for example, but not limited to, indium(III) oxide, In2O3) is a compound that removes light rays such as ultraviolet and infrared rays. When the paint of this disclosure contains indium oxide, the indium oxide is contained in an amount of 1% by mass or more and 20% by mass or less, preferably 1% by mass or more and 5% by mass or less, relative to the total amount of the paint of this disclosure. By including it within this range, the transmittance of the coating film 20 of this disclosure can be improved. Indium oxide is added, for example, as an additive. Furthermore, within these concentration ranges, the coating film 20 can be given the functionality of "wavelength selectivity," which is the ability to remove light rays of a specific wavelength, without excessively reducing the transmittance of the coating film 20 and the transparent substrate on which the coating film 20 is formed.

[0022] Indium oxide is contained in the paint of this disclosure in the form of particles 11 (Figure 2). Therefore, the paint of this disclosure contains indium oxide particles 11. The size of the particles 11 is not particularly limited, but for example, the size within the numerical range described above for the particle size of the silicon compound (e.g., 50 nm or less) can be applied. However, the particle size of the indium oxide does not need to be the same as the particle size of the silicon compound. Furthermore, the particle size of the indium oxide can be the particle size (average particle size) measured based on the above-mentioned method for measuring the particle size of the silicon compound.

[0023] Aluminum oxide (for example, but not limited to, aluminum oxide; Al2O3) is a compound that promotes heat transfer in the coating film 20. When the paint of this disclosure contains aluminum oxide, the aluminum oxide is contained in an amount of 1% by mass or more and 5% by mass or less, preferably 2% by mass or more and 5% by mass or less, relative to the total amount of the paint of this disclosure. The aluminum oxide is added, for example, as an additive. Furthermore, within these concentration ranges, heat transfer can be promoted without excessively reducing the transmittance of the coating film 20 and the transparent substrate on which the coating film 20 is formed. Therefore, new functions can be imparted to the coating film 20.

[0024] Aluminum oxide is contained in the paint of this disclosure in the form of particles 11 (Figure 2). Therefore, the paint of this disclosure contains aluminum oxide particles 11. The size of the particles 11 is not particularly limited, but for example, the size within the numerical range described above for the particle size of the silicon compound (e.g., 50 nm or less) can be applied. However, the particle size of the aluminum oxide does not need to be the same as the particle size of the silicon compound. Furthermore, the particle size of the aluminum oxide can be the particle size (average particle size) measured based on the above-mentioned method for measuring the particle size of the silicon compound.

[0025] The paint of this disclosure preferably further contains tungsten oxide (for example, but not limited to, tungsten(VI) oxide, WO3). Tungsten oxide is a compound that functions as a photocatalyst, for example, and is a compound that removes light rays such as ultraviolet and infrared rays. The tungsten oxide is contained in the paint of this disclosure in an amount of, for example, more than 0% by mass and 0.2% by mass or less, preferably more than 0% by mass and 0.1% by mass or less, relative to the total amount of the paint. By including it within this range, it is possible to suppress the excessive exertion of the photocatalytic effect. At the same time, through interaction with the aluminum oxide and indium oxide, the transmittance of the coating film 20 and the transparent substrate on which the coating film 20 is formed can be improved.

[0026] It is preferable that the tungsten oxide is included in the paint of this disclosure in the form of particles 11 (Figure 2). Therefore, it is preferable that the paint of this disclosure contains tungsten oxide particles 11. The size of the particles 11 is not particularly limited, but for example, a size within the numerical range described above for the particle size of the silicon compound (e.g., 50 nm or less) can be applied. However, the particle size of the tungsten compound does not need to be the same as the particle size of the silicon compound. Furthermore, the particle size of the tungsten oxide can be the particle size (average particle size) measured based on the above-mentioned method for measuring the particle size of the silicon compound.

[0027] The paint of this disclosure preferably further contains titanium oxide (for example, but not limited to, titanium(IV) oxide, TiO2). Similar to the tungsten oxide described above, titanium oxide is a compound that functions as a photocatalyst, for example, and is a compound that removes light rays such as ultraviolet and infrared rays. The titanium oxide is contained in the paint of this disclosure in an amount of, for example, more than 0% by mass and 10% by mass or less, preferably more than 0% by mass and 5% by mass or less, relative to the total amount of the paint. By containing it within this range, excessive photocatalytic activity can be suppressed. In addition, through interaction with the aluminum oxide and indium oxide described above, the transmittance of the coating film 20 and the transparent substrate on which the coating film 20 is formed can be improved.

[0028] It is preferable that the titanium oxide is included in the paint of this disclosure in the form of particles 11 (Figure 2). Therefore, it is preferable that the paint of this disclosure contains titanium oxide particles 11. The size of the particles 11 is not particularly limited, but for example, the size within the numerical range described above for the particle size of the silicon compound (e.g., 50 nm or less) can be applied. However, the particle size of the titanium oxide does not need to be the same as the particle size of the silicon compound. Furthermore, the particle size of the titanium oxide can be the particle size (average particle size) measured based on the above-mentioned method for measuring the particle size of the silicon compound.

[0029] As a dispersion medium (which may also be a solvent for dissolving) for dispersing each of the above components contained in the paint of this disclosure, organic solvents such as methanol, ethanol, butanol, and isopropyl alcohol are preferred. However, the dispersion medium may also be an aqueous solvent.

[0030] Furthermore, the "other components" that may constitute the paint of this disclosure include, for example, resins and any additives. The resin is preferably a resin that dissolves in a dispersion medium, such as acrylic resin or epoxy resin, or a resin-forming resin raw material such as benzophenone or acetophenone. When a resin (or resin raw material) is included, the concentration of the resin in the paint of this disclosure is, for example, 10% by mass or more and 50% by mass or less, preferably 30% by mass or more and 40% by mass or less, relative to the total amount of the paint of this disclosure. Including a resin can improve the strength of the coating film 20.

[0031] The paints disclosed herein are either room-temperature curing or ultraviolet-curing paints. Room-temperature curing paints include, for example, paints that begin curing at room temperature by reacting with components in the environment (e.g., oxygen, moisture, hydrogen), and paints that begin curing at room temperature by adding a curing initiator. For example, when using SiH2NH as an example of a silicon compound, SiH2NH reacts with moisture, hydrogen, etc. in the environment and cures at room temperature (e.g., 20°C to 30°C). Therefore, the paint is room-temperature curing. Ultraviolet-curing paints are, for example, paints that begin curing by irradiating them with ultraviolet light. By using such paints, curing can be easily achieved. Furthermore, the paints disclosed herein can be made ultraviolet-curing by incorporating, for example, an ultraviolet-curing resin such as acrylic resin into the paint.

[0032] Figure 1 is a flowchart showing a method for manufacturing the structure 100 (Figure 2) of the present disclosure (hereinafter referred to as the "manufacturing method of the present disclosure"). The structure 100 comprises a glass substrate 1 (Figure 2) that is exposed to the environment. The structure 100 is, for example, a solar panel 101 (Figure 2), and the glass substrate 1 is a glass substrate 31 (Figure 6) that covers a power generation cell 33 (Figure 6; an example of a solar cell).

[0033] The manufacturing method of the present disclosure includes a coating step S1 of applying the paint of the present disclosure to a glass substrate 1, and a curing step S2 of curing the paint of the present disclosure applied to the glass substrate 1. A coating film 20 (Figure 2) is obtained by the curing step S2.

[0034] In coating step S1, the paint is applied to the surface of the glass substrate 1 using a coating mechanism such as a sponge roller filled with the paint of this disclosure, a cloth, or a spray device. It is preferable to form a uniform film using a scraper made of plastic, rubber, metal, etc. Furthermore, to protect the surface of the glass substrate 1 and avoid the residue of dirt and unnecessary additive particles, an absorbent material such as a sponge may be attached to the scraper.

[0035] The amount of coating applied is not particularly limited, but it is preferable to apply an amount such that the thickness (film thickness) of the cured coating film 20 is, for example, 300 nm or less, preferably 250 nm or less, more preferably less than 250 nm, and even more preferably 200 nm or less. Regarding the lower limit, the thickness of the coating film 20 is greater than the size of each component in the paint (size of particles 11 (Figure 2)). By setting the thickness of the coating film 20 within this range, the transmittance of the coating film 20 and the transparent substrate on which the coating film 20 is formed can be increased. The amount of paint corresponding to the thickness of the coating film 20 can be determined, for example, by the content of the components in the paint, the size of the components (size of particles 11), etc. Furthermore, it is preferable to make the film thickness such that the reflectance is minimized, taking into account the refractive index of the glass substrate 1.

[0036] In coating the glass substrate 1, it is desirable that the coating speed be constant. Since the coating speed easily affects the film thickness, maintaining a constant coating speed allows for a uniform film thickness. Coating may be performed by automatic control using a coating apparatus equipped with the above coating mechanism.

[0037] As described above, the coating can be applied to, for example, the glass substrate 31 of the solar panel 101 (an example of a transparent substrate). In this case, it is preferable to apply it to the surface that is exposed to sunlight (the outer surface of the solar panel 101; the surface that is exposed to the environment). It is also preferable to determine the thickness of the coating 20 by considering the refractive indices of the glass substrate 1 and the coating 20 of this disclosure. Furthermore, if it is desired to further enhance the anti-reflective function or to increase the effect of additional functions, it is preferable to apply it to the surface opposite to the surface that is exposed to sunlight (the surface that emits light that has been transmitted through the glass substrate 1; the side of the power generation cell 33 (Figure 6)).

[0038] It is preferable to clean the surface of the glass substrate 1 before application. Cleaning methods include, for example, high-pressure cleaning using pure water or a cleaning solution containing a surfactant, or cleaning with alcohols for degreasing purposes. It is preferable to remove as much foreign matter as possible remaining on the surface of the glass substrate 1, such as sand, dust, and oil, through cleaning.

[0039] The curing process S2 is a process in which the coating film is cured (dried), for example, by leaving it in an atmospheric environment. The curing time can be, for example, between 2 and 8 hours. However, the curing time may vary depending on the ambient temperature, humidity, wind speed (for example, in the case of open air), etc.

[0040] Figure 2 is a schematic diagram of the structure 100 of the present disclosure. The coating film 20 (an example of a functional layer) formed on the surface of the glass substrate 1 includes, for example, a substrate 10 composed of a silicon skeleton, resin, etc., and particles 11. The particles 11 are particles of each of the above metal oxides, and include at least tin oxide particles. Furthermore, the particles 11 include at least one of indium oxide particles or aluminum oxide particles. Furthermore, it is preferable that the particles 11 include at least one of tungsten oxide or titanium oxide particles. Note that silicon oxide produced by hydrolysis of silicon compounds in the paint constitutes the substrate 10 by the above "Si-O-" bond. For this reason, as described above, silicon oxide does not normally exist as particles 11 in the coating film 20.

[0041] The particles 11 are normally dispersed within the coating film 20. This dispersion allows the entire coating film 20 to exhibit consistently good light transmittance.

[0042] Figure 3 is a diagram illustrating in detail the layer structure of the coating film 20 shown in Figure 2. The coating film 20 comprises a particle concentration layer 21 on the glass substrate 1 side and a particle diffusion layer 22 on the outer surface side of the coating film 20. The density of particles 11 in the particle concentration layer 21 (number of particles 11 per unit volume; the same applies hereinafter) is greater than the density of particles 11 in the particle diffusion layer 22. In this way, the relatively high-density particle concentration layer 21 can exhibit low reflectivity of infrared rays and high adhesion to the glass substrate 1. At the same time, the relatively low-density particle diffusion layer 22 can exhibit, for example, antifouling properties, and furthermore, various functionalities can be imparted to the coating film 20.

[0043] Such a multi-layer structure may be achieved by repeatedly applying each coating solution corresponding to the particle concentration layer 21 and the particle diffusion layer 22. However, in the example of this disclosure, the structure shown in Figure 3 can be obtained by applying the paint of this disclosure to the surface of the glass substrate 1 only once. Here, "one coat" does not mean applying the paint only once, but rather means applying one type of paint (the same type of paint) once or in multiple coats.

[0044] Furthermore, the paints disclosed herein preferably contain a binder, a silane coupling agent, etc., to improve the adhesion between the resin cured in the paint and the particles 11, in order to stabilize the refractive index of the cured coating film 20. The amount of binder used is preferably such that the fine particles of the silica compound perform the function of the silica compound while also achieving the function of the binder. [Examples]

[0045] As a silicon compound, SiH2NH (which produces silicon oxide SiO2 through hydrolysis) was prepared, and as oxides (metal oxides), particles 11 of each of SnO (an example of tin oxide), In2O3 (an example of indium oxide), Al2O3 (an example of aluminum oxide), WO3 (an example of tungsten oxide), and TiO2 (an example of titanium oxide) were prepared (Figure 2). Then, paints were prepared containing the silicon compounds and each oxide (SnO, In2O3, Al2O3, WO3, TiO2) of composition 1 to 13 listed in Table 1 in the proportions (units are mass%) listed in Table 1, with the remainder being a dispersion medium (butanol). Compositions 1 to 13 exhibit antifouling properties. Therefore, the coating film 20 obtained using paints of composition 1 to 13 has antifouling properties, and thus the coating film 20 is a layer (functional layer) with antifouling function. Among these, the paint of composition 11 is Reference Example 1, which does not contain metal particles. Furthermore, for convenience, Table 1 also shows the results (measured values ​​and evaluation results) for transmittance and stain resistance, which will be described later.

[0046] [Table 1]

[0047] The particle sizes of the silicon compounds used ranged from 20 nm to 50 nm. SnO, In2O3, Al2O3, WO3, and TiO2 all had particle sizes ranging from 20 nm to 50 nm. All particle sizes were measured using a device that measures the average particle size based on laser diffraction scattering.

[0048] The paints of compositions 1 to 13 described above were applied to a glass plate (glass substrate 1 (Figure 2). An example of a transparent substrate. Thickness 1 mm) with a refractive index of 1.52 and a transmittance of 91.5% when unpainted, and a coating film 20 was obtained by completely curing the paint. The application was performed by titrating the paint onto the glass plate and spreading it in one layer (single layer. Compositions 1 to 12) or two layers (double layer. Composition 13) with a plastic spatula. When using the paint of composition 13, the first layer, which contained the above oxides and dispersion medium but did not contain the silicon compound, was completely cured (dried). After this, another paint containing the above silicon compound and dispersion medium but not containing the above oxides was applied on top of the cured layer, and the second layer was completely cured (dried). This formed a coating film 20 consisting of a total of two layers. In the formed coating film 20, the final total component amounts were as listed in Table 1.

[0049] Drying was performed by leaving the samples indoors in a well-lit environment at approximately 20°C for about 4 hours. The thickness (film thickness) of the coating film 20 (Figure 2) varied slightly from sample to sample, but was generally between 100 nm and 300 nm. Furthermore, when the cross-section of the coating film 20 was examined with a scanning electron microscope, it was confirmed that the particles 11 were unevenly distributed on the side of the glass substrate 1, and that the coating film 20 consisted of two layers: a particle concentration layer 21 and a particle diffusion layer 22. In particular, in the coating film 20 using composition 13 which formed multiple layers, the particle concentration layer 21 and the particle diffusion layer 22 were formed alternately.

[0050] The light transmittance of the coating film 20 formed on the surface of the glass plate was measured for each wavelength. The measurement was performed using a spectrophotometer, transmitting light through the glass plate and the coating film 20, and measuring the light transmittance while sweeping the wavelength of light. The results are shown in Figures 4A to 4C (excluding compositions 1, 12, and 13). In Figures 4A to 4C, the solid line represents the graph without coating film 20 (no coating), i.e., the glass plate only. Coatings showing a transmittance similar to the solid line graph (98% to 100% of the solid line graph) were judged to have "maintained" the transmittance of the glass substrate 1. Coatings showing a transmittance greater than the solid line graph were judged to have "improved" the transmittance of the glass substrate 1 (greater than 100% of the solid line graph) due to the coating film 20. Furthermore, coatings showing a transmittance significantly lower than the solid line graph (less than 98% of the solid line graph) were judged to have "decreased" the transmittance of the glass substrate 1.

[0051] As shown in Figure 4A, both paints, Composition 2 (shown by the dashed line) and Composition 3 (shown by the dotted line), exhibited higher transmittance than that of glass substrate 1 (shown by the solid line), particularly at wavelengths below 400 nm. Therefore, it was determined that paints of Compositions 2 and 3 "improved" transmittance. However, paint of Composition 4 (shown by the dashed line) exhibited significantly lower transmittance than that of glass substrate 1 (shown by the solid line) across the entire wavelength range. Therefore, it was determined that paint of Composition 4 "decreased" transmittance.

[0052] Furthermore, as shown in Figure 4B, composition 5 (shown by the dashed line) and composition 6 (shown by the dotted line) both exhibited significantly lower transmittances than those of glass substrate 1 (shown by the solid line). In particular, the transmittance of composition 6 was generally lower than that of glass substrate 1 in the wavelength range of 300 nm to 600 nm. Therefore, it was determined that the paints of compositions 5 and 6 "reduced" the transmittance. On the other hand, the paint of composition 7 (shown by the dashed line) exhibited a transmittance that was approximately the same as that of glass substrate 1 (shown by the solid line). Therefore, it was determined that the paint of composition 7 was able to "maintain" its transmittance.

[0053] Furthermore, as shown in Figure 4C, the paint with composition 9, indicated by the thick solid line, showed a higher transmittance than that of glass substrate 1, indicated by the medium-thickness solid line, particularly in the wavelength band above 330 nm. Therefore, it was determined that the paint with composition 9 "improved" the transmittance. Furthermore, the paint with composition 10 showed a transmittance that was almost the same as that of glass substrate 1, indicated by the medium-thickness solid line. Therefore, it was determined that the paint with composition 10 was able to "maintain" the transmittance. On the other hand, the paint with composition 8 showed a transmittance that was considerably lower than that of glass substrate 1 across the entire wavelength band. Therefore, it was determined that the paint with composition 8 "decreased" the transmittance. Note that the transmittance of the paint with composition 11, which is reference example 1, was higher across the entire wavelength band than the transmittance of glass substrate 1 (transmittance without coating), indicated by the medium-thickness solid line.

[0054] Among the paints with compositions 1 to 11, some paints showed higher transmittance than glass substrate 1 in certain wavelength bands, while showing lower transmittance than glass substrate 1 in the remaining wavelength bands. Therefore, in order to evaluate the transmittance across all wavelengths, a numerical value was calculated using the following formula, and based on this value, the transmittance was judged as good (pass) or poor (fail). The numerical value and the judgment result are shown in Table 1 above.

[0055] To determine whether the transmittance was good or bad, we decided to use the average transmittance, which is the average of the wavelength transmittances in the visible light region. The average transmittance was calculated using the following formula (1). In formula (1), (transmittance) is the transmittance for each wavelength. To avoid the influence of the glass substrate 1, the calculation range was set to 400 nm to 760 nm, and the average transmittance within that range was used.

[0056]

number

[0057] In Table 1 above, paints with a transmittance of 98% or higher (89.67% or higher), which is generally considered to be higher than the transmittance of glass substrate 1 without a coating (91.5%) ("improved"), or not significantly lower than the transmittance of glass substrate 1 without a coating (i.e., "maintained"), were classified as "good." Compositions showing a transmittance of less than 98% of the transmittance of glass substrate 1 without a coating were classified as "poor."

[0058] Furthermore, the electrical resistance of the surface of the coating film 20 was measured for glass substrates 1 equipped with the above compositions 1 to 13. The electrical resistance measured was the surface resistance when a voltage of 10V was applied to the surface of the coating film 20 at 25°C. An electrical resistance value (reference value) at which dust and other particles are unlikely to adhere to the surface of the coating film 20 was determined experimentally, and coating films 20 that showed an electrical resistance of less than or equal to this reference value were classified as "good" (excellent antifouling properties). This is because, as described above, the lower the surface resistance of the coating film 20, the more static electricity is suppressed, thereby suppressing the adhesion of sand, dust, and other particles. On the other hand, coating films 20 that showed an electrical resistance of more than the reference value were classified as "poor" (inferior antifouling properties). As shown in Table 1 above, coating films 20 with good transmittance also showed good antifouling properties, while coating films 20 with poor transmittance also showed poor antifouling properties. Therefore, it has been shown that the paint of this disclosure can impart antifouling properties to the surface of a transparent substrate without significantly reducing the light transmittance.

[0059] In addition, because the paints of this disclosure contain metal oxides such as indium oxide, the coating film 20 becomes, for example, white, resulting in so-called "cloudiness." This reduces the transmittance. However, by using the paints of this disclosure, a significant decrease in transmittance could be suppressed. Furthermore, some of the paints of this disclosure, in the case of paints with a predetermined composition, were able to improve the transmittance compared to when the glass substrate 1 was used alone (for example, compositions 2 and 3). This makes it possible to enhance the functionality of the transparent substrate surface (for example, by installing transparent electrodes) without reducing the transmittance of the transparent substrate such as the glass substrate 1.

[0060] Figure 5A is an example of the reflectance measurement results for a glass substrate 1 coated with the paint of this disclosure, and is a graph showing the results for compositions 2 to 6. Figure 5B is an example of the reflectance measurement results for a glass substrate 1 coated with the paint of this disclosure, and is a graph showing the results for compositions 8 to 11. Of the light incident on the coating film 20, a portion is reflected at the surface of the coating film 20, and the remainder enters the interior of the coating film 20. Also, of the light that enters the interior of the coating film 20, a portion is absorbed, and the remainder is transmitted or reflected back to the incident side. Therefore, the sum of transmittance and reflectance does not necessarily equal 100%.

[0061] In Figures 5A and 5B, the unpainted glass substrate 1, shown by a medium-thickness solid line, has an average reflectivity of approximately 4%. On the other hand, the coating film 20, using paints with compositions 2-6 and 8-11, including the paints of this disclosure, showed a higher reflectivity than the unpainted (uncoated) substrate, but exhibited a generally similar reflectivity trend across the entire wavelength range, regardless of the presence or absence of the coating film 20. Therefore, it was found that forming a coating film 20 using the paints of this disclosure results in transmittance and reflectivity similar to that without the coating.

[0062] Figure 6 is a schematic cross-sectional view of a glass substrate 1 provided on a solar panel 101 (an example of a structure 100) with the coating of the present disclosure applied to it. The solar panel 101 comprises a glass substrate 31, a resin encapsulant 32, power generation cells 33, a back sheet 34, and a frame 35 that holds these together. The coating 20 is formed on the side of the glass substrate 31 opposite to the side where the power generation cells 33 are arranged (the side exposed to the environment).

[0063] A coating film 20 was formed using the same method as in the method used to form the coating film 20 using the paints of compositions 1 to 13 described above, and a solar panel 101 as shown in Figure 6 was fabricated. Two types of solar panels 101 were fabricated using paints of compositions 2 and 3 described above, respectively.

[0064] Figure 7A shows an example of output measurement results for a solar panel 101 to which a coating 20 has been formed by applying the paint of the present disclosure having composition 2. Figure 7B shows an example of output measurement results for a solar panel 101 to which a coating 20 has been formed by applying the paint of the present disclosure having composition 3. The graphs shown in Figures 7A and 7B are graphs that evaluate the IV characteristics, which show how much current value (short-circuit current) flows due to power generation when the voltage (open-circuit potential) shown on the horizontal axis is scanned. The specific measurement method was carried out in accordance with JISC8904. Therefore, a larger value on the vertical axis indicates higher power generation efficiency.

[0065] If the transmittance decreases due to the presence of the coating film 20, it is expected that the power generation output (current value shown on the vertical axis) will also decrease. However, as shown in Figures 7A and 7B, although the current value decreased slightly, the voltage remained almost constant. Therefore, the maximum output calculated from the current value and voltage also remained almost constant. Thus, it was found that with the paint of this disclosure, various functions such as stain resistance and thermal conductivity can be imparted to a transparent substrate such as the glass substrate 1 using the coating film 20 while maintaining or improving transmittance. [Explanation of Symbols]

[0066] 1. Glass substrate 10 Base material 100 structures 101 Solar Panels 11 particles 20 Coating film 21 Particle concentration layer 22 Particle diffusion layer 31 Glass substrate 32 Resin encapsulants 33 power generation cells 34 Backseat 35 frames S1 Coating process S2 hardening process

Claims

1. It is a paint, The paint contains 0.5% to 5% by mass of silicon compound particles, which generate silicon oxides upon curing of the paint, relative to the total amount of the paint. The paint contains tin oxide particles in an amount of 0.1% by mass or more and 5% by mass or less relative to the total amount of the paint. Furthermore, it contains particles of at least one of indium oxide or aluminum oxide, If the paint contains the indium oxide, the indium oxide particles are contained in an amount of 1% by mass or more and 20% by mass or less relative to the total amount of the paint. If the aforementioned aluminum oxide is included, the aluminum oxide particles are contained in an amount of 1% by mass or more and 5% by mass or less relative to the total amount of the paint. A paint characterized by the following features.

2. The paint according to claim 1, Furthermore, the paint contains tungsten oxide particles in an amount greater than 0% by mass and less than or equal to 0.2% by mass relative to the total amount of the paint. A paint characterized by the following features.

3. The paint according to claim 1, Furthermore, the paint contains titanium oxide particles in an amount greater than 0% by mass and less than or equal to 10% by mass relative to the total amount of the paint. A paint characterized by the following features.

4. The paint according to claim 1, The particle size of each of the silicon compound, tin oxide, indium oxide, and aluminum oxide particles is 50 nm or less. A paint characterized by the following features.

5. The paint according to claim 1, It is a paint that cures at room temperature or UV light. A paint characterized by the following features.

6. A method for manufacturing a structure comprising a glass substrate exposed to the environment, A coating step of applying the paint described in claim 1 to the glass substrate, The process includes a curing step of curing the paint applied to the glass substrate. A method for manufacturing a structure characterized by the following:

7. A method for manufacturing a structure according to claim 6, The aforementioned structure is a solar panel, The glass substrate is a component that covers the solar cell. A method for manufacturing a structure characterized by the following:

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