painted metal plate

Abstract

To further increase a photocatalytic effect while reducing a cost.SOLUTION: A coated metal plate is a metal plate having a film layer on at least one surface thereof, has: a first film layer, as the film layer, located on an outermost surface of the film layer on the at least one surface of the metal plate and at least containing a compound with photocatalytic activity (excluding the cases of a rutile-type titanium dioxide and a crystalline zirconium titanate); and a second film layer located under the first film layer and composed of an inorganic component having at least one element of Si and Zr. The first film layer has an average thickness of 0.05 to 5.00 μm, the second film layer has an average thickness of 0.10 to 5.00 μm, and a total thickness from the surface of the metal plate to the outermost surface of the film layer is 15.00 μm or less. The second film layer further contains an inorganic component having at least one element of P and V, and regarding the coated metal plate, 60° specular glossiness is 80% or more.SELECTED DRAWING: Figure 1B

Description

[Technical Field]

[0001] The present invention relates to a coated metal sheet. [Background technology]

[0002] Due to the impact of the novel coronavirus (COVID-19) over the past few years, there has been a growing need to impart antiviral properties to various items, and businesses that apply antiviral agents to the surfaces of various items are thriving. While applying antiviral agents can be applied to existing structures, there are problems with the high labor costs required for application and the lack of durability of the agents, which requires regular application, resulting in high running costs.

[0003] Meanwhile, there is a known technique for imparting antiviral properties to steel materials in advance, as described in Patent Document 1. This technique uses a coated steel material as a base and forms a protective layer and a photocatalytic layer in this order on top of the coated steel material. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-131960 Summary of the Invention [Problem to be solved by the invention]

[0005] However, as a result of investigations by the present inventors, it was found that in the technology using photocatalysts such as those disclosed in Patent Document 1, there is room for further improvement in the photocatalytic effect achieved by the photocatalyst layer.

[0006] Based on this finding, an object of the present invention is to provide a coated metal sheet that can further improve the photocatalytic effect while suppressing costs. [Means for solving the problem]

[0007] In order to solve the above problems, the present inventors conducted extensive research and found that, in the conventional technology such as that disclosed in Patent Document 1, only the light incident on the steel material contributes to the manifestation of the photocatalytic effect among the light incident on the surface of the steel material. Based on this finding, further research was conducted and it was concluded that if the incident light could be reflected more efficiently on the surface of the metal plate so that the reflected light could also contribute to the manifestation of the photocatalytic effect, it would be possible to further improve the photocatalytic effect, which led to the completion of the present invention. The gist of the present invention, which was completed based on these findings, is as follows.

[0008] (1) A coated metal sheet having a coating layer on at least one surface of the metal sheet, the coating layer comprising: a first coating layer located on the outermost surface of the coating layer on at least one surface of the metal sheet and containing at least a compound having photocatalytic activity (excluding cases where the compound having photocatalytic activity is rutile-type titanium oxide and cases where the compound having photocatalytic activity is crystalline zirconium titanate); and a second coating layer located below the first coating layer and made of an inorganic component having at least one element of Si or Zr, the average thickness of the first coating layer is 0.05 to 5.00 μm, the average thickness of the second coating layer is 0.10 to 5.00 μm, the total thickness from the surface of the metal sheet to the outermost surface of the coating layer is 15.00 μm or less, and the second coating layer further contains an inorganic component having at least one element of P or V, and the coated metal sheet satisfies JIS A coated metal sheet with a 60° specular gloss of 80% or more as specified in Z8741:1997. (2) The coated metal sheet according to (1), wherein the first coating layer further contains at least one element selected from the group consisting of Si and Zr, and the total concentration of the elements is 5 to 50 mass % in terms of silica for Si and zirconia for Zr. (3) The coated metal sheet according to (1) or (2), wherein the ratio of the average thickness of the second coating layer to the average thickness of the first coating layer is 0.3 to 12.0. (4) The coated metal sheet according to (1) or (2), wherein the second coating layer contains at least one of zirconium carbonate, ammonium zirconium carbonate, potassium zirconium carbonate, sodium zirconium carbonate, or ammonium zirconium carbonate as the inorganic component containing Zr. (5) The coated metal sheet according to (1) or (2), wherein the second coating layer contains, as the inorganic component containing P, at least one of phosphoric acid, orthophosphoric acid, metaphosphoric acid, pyrophosphoric acid, triphosphoric acid, tetraphosphoric acid and salts thereof, or ammonium dihydrogen phosphate. (6) The coated metal sheet according to (1) or (2), wherein the second coating layer contains, as the inorganic component containing V, at least one of ammonium metavanadate (V), potassium metavanadate (V), sodium metavanadate (V), or vanadyl sulfate (IV). (7) The coated metal sheet according to (1) or (2), wherein the total thickness from the surface of the metal sheet to the outermost surface of the first coating layer is 10.00 μm or less. (8) The coated metal sheet according to (1) or (2), wherein the compound having photocatalytic activity is anatase-type titanium oxide. (9) The coated metal sheet according to (8), wherein the anatase type titanium oxide is a metal-supported type titanium oxide supported on at least one of Cu and Fe. (10) The coated metal sheet according to (8), wherein the concentration of the anatase type titanium oxide in the first coating layer is 50 to 95 mass % in terms of titania. (11) The coated metal sheet according to (8), wherein the anatase type titanium oxide has an average particle size of 5 to 200 nm. (12) The coated metal sheet according to (1) or (2), wherein the metal sheet is a zinc-plated steel sheet, a zinc-aluminum alloy-plated steel sheet, a zinc-aluminum-magnesium alloy-plated steel sheet, an aluminum-plated steel sheet, a zinc-nickel alloy-plated steel sheet, a zinc-iron alloy-plated steel sheet, an aluminum sheet, or a stainless steel sheet. (13) A coated metal sheet according to (1) or (2), in which a hairline is present on the surface of the metal sheet along the rolling direction of the metal sheet. (14) A coated metal sheet according to (1) or (2), in which a spangle pattern is present on the surface of the metal sheet. [Effects of the Invention]

[0009] As described above, according to the present invention, it is possible to further improve the photocatalytic effect while suppressing costs. [Brief explanation of the drawings]

[0010] [Figure 1A] 1 is an explanatory diagram illustrating a schematic example of a structure of a coated metal plate according to an embodiment of the present invention. [Figure 1B] FIG. 4 is an explanatory diagram schematically illustrating another example of the structure of the coated metal plate according to the embodiment. [Figure 1C] FIG. 4 is an explanatory diagram schematically illustrating another example of the structure of the coated metal plate according to the embodiment. [Figure 2A] FIG. 4 is an explanatory diagram schematically illustrating another example of the structure of the coated metal plate according to the embodiment. [Figure 2B] FIG. 4 is an explanatory diagram schematically illustrating another example of the structure of the coated metal plate according to the embodiment. [Figure 3] 3 is an explanatory diagram for explaining a coated metal plate according to the embodiment; FIG. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In this specification and drawings, components having substantially the same functional configurations are designated by the same reference numerals, and redundant explanations will be omitted.

[0012] (About painted metal sheets) <Structure of painted metal sheet> Hereinafter, the structure of a coated metal sheet according to an embodiment of the present invention will be described first with reference to Figures 1A to 2B. Figure 1A is an explanatory diagram that schematically shows one example of the structure of a coated metal sheet according to this embodiment. Figures 1B to 2B are explanatory diagrams that schematically show another example of the structure of a coated metal sheet according to this embodiment.

[0013] As shown in Fig. 1A, a coated metal sheet 1 according to an embodiment of the present invention has a coating layer on at least one surface of the metal sheet, and includes at least a metal sheet 10 as a base material and a photocatalytic layer 20 as an example of a first coating layer. It may be considered to use a hard resin substrate such as melamine resin as the substrate instead of a metal sheet. However, it is important to use a substrate that can be subjected to various processes, and in this embodiment, a metal sheet is used as the substrate.

[0014] [Regarding the metal plate 10] In the coated metal sheet 1 according to this embodiment, various metal sheets can be used as the base material, the metal sheet 10. Examples of such metal sheets include zinc-plated steel sheets, zinc-aluminum alloy-plated steel sheets, zinc-aluminum-magnesium alloy-plated steel sheets, aluminum-plated steel sheets, zinc-nickel alloy-plated steel sheets, zinc-iron alloy-plated steel sheets, aluminum sheets, and stainless steel sheets.

[0015] By using such a metal sheet, it becomes possible to efficiently reflect light incident on the coated metal sheet 1 (particularly light in the ultraviolet to visible light range) from the surface of the metal sheet 10. As a result, with the coated metal sheet 1 according to this embodiment, it becomes possible to utilize the light reflected from the surface of the metal sheet 10 for a photocatalytic reaction, as will be described later. Among the above metal sheets, zinc-aluminum-magnesium alloy-plated steel sheets, stainless steel sheets, aluminum-plated steel sheets, zinc-plated steel sheets, zinc-aluminum alloy-plated steel sheets, and the like are particularly suitable because they can efficiently reflect incident light. Furthermore, those having designs such as hairlines or spangle patterns on the plated surface are suitable because they can also be used as exterior components.

[0016] Here, the thickness of the metal plate 10 as described above is not particularly limited, and may be set appropriately depending on the mechanical strength (e.g., tensile strength, etc.) and processability required for the painted metal plate 1 of this embodiment.

[0017] Furthermore, the surface of the metal sheet 10 (when a metal sheet having various platings is used as the metal sheet 10, the surface of the plating) may have various patterns such as a hairline pattern or a spangle pattern along the rolling direction of the metal sheet. The provision of such patterns makes it possible to further improve the design of the coated metal sheet 1. Furthermore, the design processing itself for providing such patterns on the surface of the metal sheet 10 also contributes to further improvement of the 60° specular gloss, as described below.

[0018] For example, let us consider a plated metal sheet 10. Generally, electroplating or hot-dip plating can be used to plate the surface of a metal substrate. Depending on the plating method used, fine particles may be generated on the plated surface, resulting in a decrease in the glossiness of the plated metal sheet 10 (i.e., the glossiness of the plated surface). However, by applying a hairline finish to such a plated surface, the plated surface is scraped, improving the light reflectance of the plated surface and making it possible to improve the surface glossiness. Furthermore, by plating to form a spangle pattern, the crystal orientation of the plating that is more reflective of light becomes apparent on the surface, improving the light reflectance of the plated surface and making it possible to improve the surface glossiness.

[0019] As will be described in detail below, in the coated metal sheet 1, the thickness of the photocatalytic layer 20 as the first coating layer and the total thickness from the surface of the metal sheet 10 to the outermost surface of the photocatalytic layer 20 as the first coating layer are controlled to be in a specific state. Furthermore, by applying a design process such as the hairline pattern or spangle pattern described above, the design process also serves to further improve the 60° specular gloss, as will be described below. Various known processing methods can be used as appropriate to form such patterns.

[0020] [About the photocatalytic layer 20] In the coated metal sheet 1 according to this embodiment, the photocatalytic layer 20, which is an example of a first coating layer, is a layer located on the outermost surface of the coating layer on at least one side of the metal sheet 10, as shown schematically in FIG. 1A, and contains at least a compound having photocatalytic activity (hereinafter, sometimes abbreviated as "photocatalytic compound"). When the photocatalytic layer 20 contains a compound having photocatalytic activity, the compound having photocatalytic activity causes a photocatalytic reaction in response to light (particularly light in the ultraviolet to visible light range) incident on the photocatalytic layer 20. As a result, the photocatalytic layer 20 according to this embodiment exhibits various photocatalytic effects, including antiviral and bactericidal effects. This allows the coated metal sheet 1 according to this embodiment to achieve various properties, including antiviral and bactericidal effects.

[0021] Compounds having such photocatalytic activity include compounds that react mainly with light in the ultraviolet light range (more specifically, when excited by light in the ultraviolet light range) to exhibit photocatalytic activity, and compounds that react mainly with light in the visible light range (more specifically, when excited by light in the visible light range) to exhibit photocatalytic activity.

[0022] Examples of compounds that react with light in the ultraviolet range to exhibit photocatalytic activity include metal oxides such as titanium oxide (more specifically, anatase titanium oxide), zinc oxide, cerium oxide, tin oxide, bismuth oxide, zirconium oxide, tungsten oxide, chromium oxide, molybdenum oxide, iron oxide, nickel oxide, ruthenium oxide, cobalt oxide, copper oxide, manganese oxide, germanium oxide, lead oxide, cadmium oxide, vanadium oxide, niobium oxide, tantalum oxide, rhodium oxide, and rhenium oxide, metal sulfides such as cadmium sulfide and zinc sulfide, and titanium compounds such as strontium titanate and barium titanate. Among these, anatase titanium oxide, zinc oxide, tin oxide, zirconium oxide, tungsten oxide, iron oxide, niobium oxide, and strontium titanate are particularly preferred as compounds that react with light in the ultraviolet range to exhibit photocatalytic activity, with anatase titanium oxide being even more preferred.

[0023] Examples of compounds that react with light in the visible light range to exhibit photocatalytic activity include metal-supported titanium oxide (more specifically, anatase-type titanium oxide) supported on at least one of Cu and Fe, anatase-type titanium oxide supported on Cr, V, Mn, Ni, or Pt, anatase-type titanium oxide doped with anions such as nitrogen or sulfur, and a solid solution of AgNbO3 and SrTiO3. Of these, anatase-type titanium oxide supported on at least one of Cu and Fe is particularly suitable.

[0024] Among these photocatalytic compounds, the average particle size (primary particle size) of anatase type titanium oxide (including that in a metal-supported state) is preferably 5 nm or more. By making the average particle size (primary particle size) of anatase type titanium oxide 5 nm or more, it becomes possible to disperse anatase type titanium oxide more uniformly in the photocatalytic layer 20. The average particle size (primary particle size) of anatase type titanium oxide is more preferably 20 nm or more. Furthermore, the average particle size (primary particle size) of anatase type titanium oxide (including that in a metal-supported state) is preferably 200 nm or less. By making the average particle size (primary particle size) of anatase type titanium oxide 200 nm or less, it becomes possible to disperse anatase type titanium oxide more uniformly in the photocatalytic layer 20 while suppressing excessive aggregation of anatase type titanium oxide in the photocatalytic layer 20. The average particle size (primary particle size) of anatase type titanium oxide is more preferably 100 nm or less.

[0025] The average particle size of the anatase-type titanium oxide can be measured, for example, by dynamic light scattering using a laser beam. This method allows for easy and accurate measurement. However, if the anatase-type titanium oxide particles are aggregated to some extent, it is possible to measure the size of the aggregates (aggregate particle size). Therefore, it is preferable to also directly confirm the primary particle size using a transmission electron microscope (TEM). If the presence of aggregated particles is confirmed as a result of TEM observation, it is preferable to change the dispersion conditions and measure again using dynamic light scattering. Furthermore, if it is difficult to completely disperse the particles to the primary particle level, it is also possible to use the size of the primary particles observed and measured by TEM as the primary particle size. In this case, the inventor's experience has shown that a value representative of the entire particle population can be obtained by measuring approximately 100 or more randomly selected particles.

[0026] Furthermore, when measuring the average particle size of anatase-type titanium oxide contained in the photocatalyst layer 20 of a coated metal sheet 1 on which a photocatalyst layer 20 has already been formed, the following procedure can be used. Specifically, the cross section of the photocatalyst layer 20 cut along the thickness direction can be observed or analyzed using a transmission electron microscope (TEM). The primary particle size of the photocatalyst compound can be measured using TEM. Furthermore, EDS analysis can be performed in combination with TEM to measure the elements contained in the photocatalyst compound. Furthermore, the crystal structure of the photocatalyst compound (for example, whether titanium oxide is anatase-type or rutile-type) can be determined by electron beam diffraction. The inventor's experience has shown that a value representative of the entire particle population can be obtained by measuring approximately 100 or more randomly selected particles.

[0027] Here, the concentration of anatase type titanium oxide (including that in a metal-supported state) in the photocatalyst layer 20 is preferably 50% by mass or more in titania equivalent. When the concentration of anatase type titanium oxide in the photocatalyst layer 20 is 50% by mass or more, it becomes possible to reliably exhibit various photocatalytic effects, including antiviral effects. The concentration of anatase type titanium oxide in the photocatalyst layer 20 is more preferably 60% by mass or more in titania equivalent. Furthermore, the concentration of anatase type titanium oxide (including that in a metal-supported state) in the photocatalyst layer 20 is preferably 95% by mass or less in titania equivalent. When the concentration of anatase type titanium oxide in the photocatalyst layer 20 is 95% by mass or less, it becomes possible to exhibit various photocatalytic effects, including antiviral effects, while suppressing increases in manufacturing costs. The concentration of anatase type titanium oxide in the photocatalyst layer 20 is more preferably 80% by mass or less in titania equivalent.

[0028] Similarly to the above, photocatalytic compounds other than anatase type titanium oxide preferably have an average particle size of 5 to 200 nm, and their concentration is preferably 50 to 95% by mass.

[0029] In addition, the photocatalytic compounds represented by the above-mentioned anatase type titanium oxide and the like can be used, if necessary, not only in particulate form, but also in sol-like form that cannot be said to be particulate, and substances produced by heating metal complexes.

[0030] The photocatalyst layer 20 further contains at least one element of Si or Zr, and the total concentration of such elements is preferably 5% by mass or more in terms of silica for Si and 5% by mass or more in terms of zirconia for Zr. In other words, the photocatalyst layer 20 is an inorganic coating having a skeleton of inorganic components with a three-dimensional network structure containing at least one element of Si or Zr, and possibly impurities, and the total concentration of at least one element of Si or Zr is preferably 5% by mass or more in terms of silica for Si and zirconia for Zr. By containing at least one element of Si or Zr in the above concentrations, it is possible to realize a photocatalyst layer 20 with better corrosion resistance. The total content of at least one element of Si or Zr is more preferably 10% by mass or more. The photocatalytic layer 20 further contains at least one element of Si or Zr, and the total concentration of such elements is preferably 50 mass % or less in terms of silica for Si and zirconia for Zr. By containing at least one element of Si or Zr at the above concentrations, it is possible to realize a photocatalytic layer 20 with better corrosion resistance. The total content of at least one element of Si or Zr is more preferably 40 mass % or less. Here, the contained Si or Zr preferably has excellent light transmittance and is preferably an inorganic component that is not easily affected by decomposition by the photocatalyst. Examples of such inorganic components containing Si and Zr include silica and zirconia.

[0031] The photocatalyst layer 20 containing the above-mentioned photocatalyst compound may contain an antibacterial agent or an adsorbent such as activated carbon or zeolite, if necessary, within a range that does not impair the effects of the present invention.

[0032] The average thickness d1 of the photocatalytic layer 20 (in the case of the layer structure shown in FIG. 1A ) is the total thickness d from the surface of the metal plate 10 to the outermost surface of the photocatalytic layer 20 (which can also be regarded as the outermost surface of the coating layer). T ) is 0.05 μm or more. If the average thickness d1 of the photocatalyst layer 20 is less than 0.05 μm, it becomes difficult to uniformly form the photocatalyst layer 20 as described above, and the obtained photocatalytic effect becomes uneven, which is undesirable. By setting the average thickness d1 to 0.05 μm or more, it becomes possible to uniformly exhibit the desired photocatalytic effect throughout the photocatalyst layer 20. On the other hand, the average thickness d1 of the photocatalyst layer 20 (in the case of the layer structure shown in FIG. 1A, the total thickness d from the surface of the metal plate 10 to the outermost surface of the photocatalyst layer 20) is 0.05 μm or more. T ) is 5.00 μm or less. If the average thickness d1 of the photocatalyst layer 20 exceeds 5.00 μm, the obtained photocatalytic effect saturates while the manufacturing cost increases, which is undesirable. In addition, since the photocatalyst layer is an inorganic coating, its processability decreases. By setting the average thickness d1 to 5.00 μm or less, it is possible to suppress the increase in manufacturing cost and the decrease in processability, while uniformly exhibiting the desired photocatalytic effect throughout the photocatalyst layer 20.

[0033] Normally, there is a certain probability that light passes through the photocatalytic layer 20 without hitting the photocatalytic compound. Conventionally, such light that does not interact with the photocatalytic compound is light that does not provide a photocatalytic effect. In this embodiment, by reflecting such light on the surface of the metal plate 10, it is possible to increase the probability that light incident on the photocatalytic layer 20 will hit the photocatalytic compound. As a result, in this embodiment, the photocatalytic effect can be further improved. In the case of the layer configuration shown in FIG. 1A, the total thickness d from the surface of the metal plate 10 to the outermost surface of the photocatalytic layer 20 is 1 / 2 . T is naturally 15.00 μm or less, and as a result, the incident light reflected on the surface of the metal plate 10 (in other words, the interface between the metal plate 10 and the photocatalytic layer 20) can be used for the photocatalytic reaction by the photocatalytic compound, thereby making it possible to further improve the photocatalytic effect while suppressing costs.

[0034] The average thickness d1 of the photocatalyst layer 20 is preferably 0.10 μm or more, more preferably 0.15 μm or more, and is preferably 2.00 μm or less, more preferably 1.00 μm or less.

[0035] [60° specular gloss] In the coated metal sheet 1 having the layer structure shown in FIG. 1A , the 60° specular gloss, as defined in JIS Z8741:1997, measured from the side where the photocatalyst layer 20 is provided is 80% or higher due to light reflection by the metal sheet 10 and the photocatalyst layer 20 having the average thickness d1 described above. In other words, the coated metal sheet 1 according to this embodiment has a 60° specular gloss of 80% or higher, as described above. This enables the coated metal sheet 1 to effectively utilize the reflected light generated at the interface between the metal sheet 10 and the photocatalyst layer 20, thereby exhibiting excellent antiviral performance. Although light that collides with the photocatalyst is not detected as reflected light, in the coating structure of the present invention, such light represents only a small portion of the total. Therefore, even taking into account the reduction due to the photocatalyst, a coated metal sheet 1 according to this embodiment can be determined to have excellent antiviral performance if it satisfies the 60° specular gloss of 80% or higher as defined in this invention. In the coated metal sheet 1 according to this embodiment, the 60° specular gloss is preferably 90% or higher, and more preferably 130% or higher. Although the upper limit of the 60° specular gloss is not particularly specified, it is difficult for it to exceed 200%, and this value is considered to be the practical upper limit. The 60° specular gloss can be measured using a gloss meter conforming to the above-mentioned JIS standard.

[0036] <Modification> The coated metal sheet 1 according to this embodiment, which has the layer structure shown in Fig. 1A, may have an additional coating layer that functions as a chemical conversion coating layer between the metal sheet 10 and the photocatalyst layer 20. By providing a chemical conversion coating layer between the metal sheet 10 and the photocatalyst layer 20, it is possible to further improve the adhesion between the metal sheet 10 and the photocatalyst layer 20. Furthermore, it is also possible to further improve the corrosion resistance and other properties of the coated metal sheet 1 according to this embodiment.

[0037] When a chemical conversion coating layer is further provided on the coated metal sheet 1 according to this embodiment, it is preferable to realize the following two types of layer structures depending on the types of compound components that make up the chemical conversion coating layer. The layer structures of coated metal sheets having a chemical conversion coating layer will be described in detail below with reference to Figures 1B to 3. 1B to 2 are explanatory diagrams that schematically show another example of the structure of the coated metal sheet according to this embodiment, and Fig. 3 is an explanatory diagram for explaining the coated metal sheet according to this embodiment.

[0038] [When applying an inorganic chemical conversion coating layer] 1B and 1C are schematic diagrams showing the layer structure of a coated metal sheet 1 when an inorganic chemical conversion coating layer made of inorganic components is provided as the chemical conversion coating layer. In such a case, the coated metal sheet 1 according to this embodiment has an inorganic chemical conversion coating layer 30 as an example of a second coating layer between the metal sheet 10 and the photocatalytic layer 20 as described above.

[0039] Photocatalytic compounds such as anatase titanium oxide have extremely excellent oxidizing properties, so when a coating layer is provided below the layer containing the photocatalytic compound, a protective layer is often formed to protect the coating layer. However, as explained below, by forming the chemical conversion treatment coating layer from inorganic components, it becomes possible to provide the chemical conversion treatment coating layer without providing a protective layer.

[0040] The inorganic chemical conversion coating layer 30 is formed by chemical conversion treatment after removing impurities such as oil and surface oxides adhering to the surface of the metal sheet 10 through known degreasing and cleaning processes. The inorganic chemical conversion coating layer 30 is preferably made of an inorganic component containing at least one of Si and Zr. The inorganic chemical conversion coating layer 30 may also contain an inorganic component containing at least one of P and V.

[0041] The inorganic chemical conversion coating layer 30 contains inorganic components having the elements described above, which improves the film-forming properties after application of the chemical conversion treatment solution, the barrier properties (density) of the coating against corrosive factors such as moisture and corrosive ions, and the adhesion of the coating to the metal sheet surface, thereby contributing to improving the corrosion resistance of the coating.

[0042] Examples of inorganic components containing Si include γ-(2-aminoethyl)aminopropyltrimethoxysilane, γ-(2-aminoethyl)aminopropylmethyldimethoxysilane, γ-(2-aminoethyl)aminopropyltriethoxysilane, etc. Examples of inorganic components containing Zr include zirconium carbonate, ammonium zirconium carbonate, potassium zirconium carbonate, sodium zirconium carbonate, ammonium zirconium carbonate, etc.

[0043] Examples of inorganic components containing P include phosphoric acids such as phosphoric acid, orthophosphoric acid, metaphosphoric acid, pyrophosphoric acid, triphosphoric acid, and tetraphosphoric acid, and salts thereof, and ammonium dihydrogen phosphate. Examples of inorganic components containing V include ammonium metavanadate (V), potassium metavanadate (V), sodium metavanadate (V), and vanadyl sulfate (IV).

[0044] The various inorganic components described above can be used alone or in combination in the inorganic chemical conversion coating layer 30 according to this embodiment. The contents of the various inorganic components described above can also be adjusted as appropriate.

[0045] The average thickness d2 of the inorganic chemical conversion treatment film layer 30 is preferably 0.10 μm or more, and more preferably 0.20 μm or more. This allows the inorganic chemical conversion treatment film layer 30 to be uniformly formed on the surface of the metal sheet 10, while the various effects achieved by providing the chemical conversion treatment film layer as described above can be stably exhibited. Furthermore, the average thickness d2 of the inorganic chemical conversion treatment film layer 30 is preferably 5.00 μm or less, and more preferably 1.00 μm or less. This allows the inorganic chemical conversion treatment film layer 30 to be uniformly formed on the surface of the metal sheet 10, while the various effects achieved by providing the chemical conversion treatment film layer as described above can be stably exhibited.

[0046] Furthermore, the ratio (d2 / d1) of the average thickness d2 of the inorganic chemical conversion coating layer 30 to the average thickness d1 of the photocatalyst layer 20 is preferably 0.3 or more, and more preferably 0.5 or more. This makes it possible to further improve the adhesion during processing. Furthermore, the ratio (d2 / d1) of the average thickness d2 of the inorganic chemical conversion coating layer 30 to the average thickness d1 of the photocatalyst layer 20 is preferably 12.0 or less, and more preferably 5.0 or less. This makes it possible to further improve the adhesion during processing.

[0047] Furthermore, as shown schematically in FIG. 1C, the coated metal sheet 1 according to this embodiment may further include various known layers between the photocatalytic layer 20 and the inorganic chemical conversion coating layer 30, such as colored layers containing various color pigments.

[0048] 1B and 1C, the total thickness d from the surface of the metal plate 10 to the outermost surface of the coating layer (which is also the outermost surface of the photocatalytic layer 20) T(=d1+d2+α) is set to 15.00 μm or less. As a result, as shown in FIG. 3, it becomes possible to utilize the incident light reflected on the surface of the metal plate 10 (in other words, the interface between the metal plate 10 and the photocatalytic layer 20) for the photocatalytic reaction by the photocatalytic compound, thereby suppressing an increase in cost and further improving the photocatalytic effect. The total thickness d from the surface of the metal plate 10 to the outermost surface of the coating layer T (=d1+d2+α) is preferably 10.00 μm or less, and more preferably 7.00 μm or less.

[0049] 1B and 1C, the 60° specular gloss of the coated metal sheet 1 measured from the side on which the photocatalytic layer 20 is provided, as defined in JIS Z8741:1997, is 80% or more. T is 15.00 μm or less and the 60° specular gloss is 80% or more, it can be considered that the incident light reflected on the surface of the metal plate 10 is utilized for the photocatalytic reaction by the photocatalytic compound.

[0050] [When applying an organic chemical conversion coating layer] 2A and 2B are schematic diagrams showing the layer structure of a coated metal sheet 1 when an organic chemical conversion coating layer containing an organic component is provided as the chemical conversion coating layer. In such a case, the painted metal sheet 1 according to this embodiment has, between the metal sheet 10 and the photocatalyst layer 20 as described above, an organic chemical conversion coating layer 40 as an example of a third coating layer, and a protective layer 50 as an example of a fourth coating layer.

[0051] <Organic chemical conversion coating layer 40> The organic chemical conversion coating layer 40 is a layer located below the photocatalytic layer 20 (more specifically, on the surface of the metal plate 10), and is formed by chemical conversion treatment after impurities such as oil and surface oxides adhering to the surface of the metal plate 10 are removed by known degreasing and cleaning processes.

[0052] The organic chemical conversion coating layer 40 according to this embodiment may contain, for example, one or more selected from the group consisting of resin, silane coupling agent, zirconium compound, silica, phosphoric acid and its salts, fluoride, vanadium compound, and tannin or tannic acid. The inclusion of these substances further improves the film-forming properties after application of the chemical conversion treatment solution, the barrier properties (density) of the coating against corrosion factors such as moisture and corrosive ions, and the adhesion of the coating to the surface of the metal sheet, thereby contributing to an overall improvement in the corrosion resistance of the coating.

[0053] In particular, when the organic chemical conversion coating layer 40 contains one or more of a silane coupling agent or a zirconium compound, a crosslinked structure is formed within the organic chemical conversion coating layer 40, which also strengthens the bond with the metal sheet surface, making it possible to further improve the adhesion and barrier properties of the coating.

[0054] Furthermore, when the organic chemical conversion coating layer 40 contains one or more of silica, phosphoric acid and its salts, fluoride, or vanadium compounds, these act as inhibitors to form a precipitated film or a passive film on the surface of the metal sheet, thereby further improving corrosion resistance.

[0055] Below, the details of each of the constituent components that may be contained in the organic chemical conversion coating layer 40 as described above will be explained with examples.

[0056] [resin] As the resin, known organic resins such as polyester resin, polyurethane resin, epoxy resin, phenolic resin, acrylic resin, polyolefin resin, etc. can be used. To further improve adhesion to the metal plate, it is preferable to use at least one resin having a forced moiety or a polar functional group in the molecular chain (polyester resin, urethane resin, epoxy resin, acrylic resin, etc.). The resin may be used alone or in combination of two or more types.

[0057] The resin content in the organic chemical conversion coating layer 40 is, for example, preferably 0% by mass or more, and more preferably 1% by mass or more, relative to the solid content of the coating. This improves corrosion resistance. Furthermore, the resin content in the organic chemical conversion coating layer 40 is, for example, preferably 85% by mass or less, more preferably 60% by mass or less, and even more preferably 40% by mass or less, relative to the solid content of the coating. By keeping the resin content at 85% by mass or less, the corrosion resistance of the coating can be improved while ensuring the performance required of the coating other than corrosion resistance.

[0058] [Silane coupling agents] Examples of the silane coupling agent include γ-(2-aminoethyl)aminopropyltrimethoxysilane, γ-(2-aminoethyl)aminopropylmethyldimethoxysilane, γ-(2-aminoethyl)aminopropyltriethoxysilane, γ-(2-aminoethyl)aminopropylmethyldiethoxysilane, γ-(2-aminoethyl)aminopropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropyltriethoxy ... Dipropylmethyldiethoxysilane, N-β-(N-vinylbenzylaminoethyl)-γ-aminopropyltrimethoxysilane, N-β-(N-vinylbenzylaminoethyl)-γ-aminopropylmethyldimethoxysilane, N-β-(N-vinylbenzylaminoethyl)-γ-aminopropyltriethoxysilane, N-β-(N-vinylbenzylaminoethyl)-γ-aminopropylmethyldiethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropyltriethoxy Silane, γ-glycidoxypropylmethyldiethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropylmethyldimethoxysilane, γ-mercaptopropyltriethoxysilane, γ-mercaptopropylmethyldiethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, vinyltriacetoxysilane, γ-chloropropyltrimethoxysilane, γ-chloropropylmethyldimethoxysilane, γ-chloropropyltriethoxysilane, γ-chloropropyl vinylmethyldiethoxysilane, hexamethyldisilazane, γ-anilinopropyltrimethoxysilane, γ-anilinopropylmethyldimethoxysilane, γ-anilinopropyltriethoxysilane, γ-anilinopropylmethyldiethoxysilane, vinyltrimethoxysilane, vinylmethyldimethoxysilane, vinyltriethoxysilane, vinylmethyldiethoxysilane, octadecyldimethyl[3-(trimethoxysilyl)propyl]ammonium chloride, octadecyldimethyl[3-(methyldimethoxysilyl)propyl]ammonium chloride,Examples of suitable silane coupling agents include octadecyldimethyl[3-(triethoxysilyl)propyl]ammonium chloride, octadecyldimethyl[3-(methyldiethoxysilyl)propyl]ammonium chloride, γ-chloropropylmethyldimethoxysilane, γ-mercaptopropylmethyldimethoxysilane, methyltrichlorosilane, dimethyldichlorosilane, and trimethylchlorosilane. The amount of silane coupling agent added to the chemical conversion coating agent for forming the organic chemical conversion coating layer 40 can be, for example, 2 to 80 g / L. By adding 2 g / L or more of the silane coupling agent, adhesion to the metal sheet surface can be improved, thereby improving the processing adhesion of the coating film. Furthermore, by adding 80 g / L or less of the silane coupling agent, the cohesive strength of the chemical conversion coating film can be maintained, thereby improving the processing adhesion of the coating film. The silane coupling agents exemplified above may be used alone or in combination of two or more.

[0059] [Zirconium compounds] Examples of zirconium compounds include zirconium normal propylate, zirconium normal butylate, zirconium tetraacetylacetonate, zirconium monoacetylacetonate, zirconium bisacetylacetonate, zirconium monoethylacetoacetate, zirconium acetylacetonate bisethylacetoacetate, zirconium acetate, zirconium monostearate, zirconium carbonate, ammonium zirconium carbonate, potassium zirconium carbonate, and sodium zirconium carbonate. The amount of zirconium compound added to the chemical conversion treatment agent for forming the organic chemical conversion coating layer 40 can be, for example, 2 to 80 g / L. By adding the zirconium compound in an amount of 2 g / L or more, adhesion to the metal sheet surface can be improved, thereby improving the processing adhesion of the coating film. Furthermore, by adding the zirconium compound in an amount of 80 g / L or less, the cohesive strength of the chemical conversion coating film can be maintained, thereby improving the processing adhesion of the coating film. Such zirconium compounds may be used alone or in combination of two or more.

[0060] [silica] Examples of silica that can be used include commercially available silica gels such as "Snowtex N," "Snowtex C," "Snowtex UP," and "Snowtex PS" manufactured by Nissan Chemical Industries, Ltd., and "Adelite AT-20Q" manufactured by ADEKA Corporation, as well as powdered silica such as Aerosil #300 manufactured by Nippon Aerosil Co., Ltd. The type of silica can be selected appropriately depending on the required performance of the coated metal sheet. The amount of silica added to the chemical conversion treatment agent for forming the organic chemical conversion coating layer 40 is preferably 1 to 40 g / L. Adding silica at a level of 1 g / L or more can improve the processing adhesion of the coating film. Furthermore, adding silica at a level of 40 g / L or less can achieve both processing adhesion and corrosion resistance while suppressing cost increases.

[0061] [Phosphoric acid and its salts] Examples of phosphoric acid and its salts include phosphoric acids such as orthophosphoric acid, metaphosphoric acid, pyrophosphoric acid, triphosphoric acid, and tetraphosphoric acid, and their salts; ammonium salts such as triammonium phosphate and diammonium hydrogen phosphate; phosphonic acids such as aminotri(methylenephosphonic acid), 1-hydroxyethylidene-1,1-diphosphonic acid, ethylenediaminetetra(methylenephosphonic acid), and diethylenetriaminepenta(methylenephosphonic acid), and their salts; and organic phosphoric acids such as phytic acid and their salts. Phosphoric acid salts other than ammonium salts include metal salts with Na, Mg, Al, K, Ca, Mn, Ni, Zn, Fe, and the like. Phosphoric acid and its salts may be used alone or in combination of two or more.

[0062] The content of phosphoric acid and its salts is preferably 0% by mass or more, and more preferably 1% by mass or more, based on the solid content of the coating. Furthermore, the content of phosphoric acid and its salts is preferably 20% by mass or less, and more preferably 10% by mass or less, based on the solid content of the coating. By keeping the content of phosphoric acid and its salts at 20% by mass or less, embrittlement of the coating can be prevented, and a decrease in the coating adhesion during forming of the coated metal sheet can be prevented.

[0063] [Fluoride] Examples of fluorides include ammonium zirconate fluoride, ammonium silicofluoride, ammonium titanium fluoride, sodium fluoride, potassium fluoride, calcium fluoride, lithium fluoride, titanium hydrofluoric acid, zirconate hydrofluoric acid, etc. Such fluorides may be used alone or in combination of two or more.

[0064] The fluoride content is preferably 0% by mass or more, and more preferably 1% by mass or more, based on the solid content of the coating. The fluoride content is preferably 20% by mass or less, and more preferably 10% by mass or less, based on the solid content of the coating. By keeping the fluoride content at 20% by mass or less, embrittlement of the coating can be prevented, and a decrease in the coating adhesion during processing when the coated metal sheet is formed can be prevented.

[0065] [Vanadium compounds] Examples of vanadium compounds include vanadium compounds obtained by reducing pentavalent vanadium compounds such as vanadium pentoxide, metavanadic acid, ammonium metavanadate, sodium metavanadate, and vanadium oxytrichloride with a reducing agent to divalent to tetravalent vanadium compounds, and vanadium trioxide, vanadium dioxide, vanadium oxysulfate, vanadium oxyoxalate, vanadium oxyacetylacetonate, vanadium acetylacetonate, vanadium trichloride, vanadium phosphomolybdic acid, vanadium sulfate, vanadium dichloride, and vanadium oxide, and other vanadium compounds having an oxidation number of tetravalent to divalent. These vanadium compounds may be used alone or in combination of two or more.

[0066] The content of the vanadium compound is preferably 0% by mass or more, and more preferably 1% by mass or more, based on the solid content of the coating. Furthermore, the content of the vanadium compound is preferably 20% by mass or less, and more preferably 10% by mass or less, based on the solid content of the coating. By keeping the vanadium compound content at 20% by mass or less, it is possible to prevent embrittlement of the coating and to prevent a decrease in the processing adhesion of the coating when the coated metal sheet is formed.

[0067] [Tannin or tannic acid] The tannin or tannic acid may be either a hydrolyzable tannin or a condensed tannin. Examples of tannin and tannic acid include ham meta tannin, Chinese gall tannin, gall nut tannin, myrobalan tannin, dividivi tannin, algarovila tannin, valonia tannin, and catechin. The amount of tannin or tannic acid added to the chemical conversion treatment agent for forming the organic chemical conversion coating layer 40 can be 2 to 80 g / L. By adding tannin or tannic acid in an amount of 2 g / L or more, adhesion to the metal sheet surface can be improved, thereby improving the processing adhesion of the coating film. Furthermore, by adding tannin or tannic acid in an amount of 80 g / L or less, the cohesive strength of the chemical conversion coating film can be maintained, improving the processing adhesion of the coating film.

[0068] Furthermore, an acid, alkali, or the like may be added to the chemical conversion treatment agent used to form the organic chemical conversion coating layer 40 in order to adjust the pH, as long as the performance is not impaired.

[0069] The average thickness d3 of the organic chemical conversion treatment film layer 40 is preferably 0.10 μm or more, more preferably 0.20 μm or more, and even more preferably 0.30 μm or more. This allows the organic chemical conversion treatment film layer 40 to be uniformly formed on the surface of the metal sheet 10, while stably achieving the various effects achieved by providing the chemical conversion treatment film layer described above. Furthermore, the average thickness d3 of the organic chemical conversion treatment film layer 40 is preferably 5.00 μm or less, more preferably 4.00 μm or less, and even more preferably 3.00 μm or less. This allows the organic chemical conversion treatment film layer 40 to be uniformly formed on the surface of the metal sheet 10, while stably achieving the various effects achieved by providing the chemical conversion treatment film layer described above.

[0070] Furthermore, the ratio (d3 / d1) of the average thickness d3 of the organic chemical conversion coating layer 40 to the average thickness d1 of the photocatalyst layer 20 is preferably 0.5 or more, and more preferably 2.0 or more. This makes it possible to further improve adhesion to the processed area. Furthermore, the ratio (d3 / d1) of the average thickness d3 of the organic chemical conversion coating layer 40 to the average thickness d1 of the photocatalyst layer 20 is preferably 20.0 or less, and more preferably 10.0 or less. This makes it possible to further improve adhesion to the processed area.

[0071] ≪Protective layer 50≫ The protective layer 50 is a layer provided between the photocatalyst layer 20 and the organic chemical conversion coating layer 40 (more preferably, directly below the photocatalyst layer 20), and is provided to protect layers located below the photocatalyst layer 20 from the oxidizing power of the photocatalytic compound contained in the photocatalyst layer 20.

[0072] Here, the protective layer 50 may contain various known components. Examples of such components include inorganic oxides such as silica and zirconia. The specific content of such components may also be adjusted as appropriate.

[0073] It is preferable that the protective layer 50 also has excellent light transmittance, similar to the photocatalyst layer 20. In order to realize a protective layer 50 with excellent light transmittance, for example, it is possible to use the same components as the components in the photocatalyst layer 20 other than the photocatalytic compound.

[0074] The average thickness d4 of the protective layer 50 is preferably 0.05 μm or more, and more preferably 0.20 μm or more. This makes it possible to reliably protect the layers located below the protective layer 50 from the oxidizing power of the photocatalytic compound while suppressing a decrease in processability. Furthermore, the average thickness d4 of the protective layer 50 is preferably 5.00 μm or less, and more preferably 0.60 μm or less. This makes it possible to reliably protect the layers located below the protective layer 50 from the oxidizing power of the photocatalytic compound while suppressing a decrease in processability.

[0075] Furthermore, the ratio (d4 / d1) of the average thickness d4 of the protective layer 50 to the average thickness d1 of the photocatalyst layer 20 is preferably 0.3 or more, and more preferably 1.0 or more. This makes it possible to reliably suppress decomposition of the organic chemical conversion treatment film layer 40 by the photocatalyst layer 20. Furthermore, the ratio (d4 / d1) of the average thickness d4 of the protective layer 50 to the average thickness d1 of the photocatalyst layer 20 is preferably 20.0 or less, and more preferably 3.0 or less. This makes it possible to reliably suppress decomposition of the organic chemical conversion treatment film layer 40 by the photocatalyst layer 20.

[0076] Furthermore, as shown schematically in FIG. 2B, the coated metal sheet 1 according to this embodiment may further include various known layers, such as colored layers containing various color pigments, between the photocatalytic layer 20 and the protective layer 50 and the organic chemical conversion coating layer 40.

[0077] 2A and 2B, the total thickness d from the surface of the metal plate 10 to the outermost surface of the coating layer (which is also the outermost surface of the photocatalytic layer 20) T(=d1+d3+d4+α) is set to 15.00 μm or less. As a result, as shown in FIG. 3, it becomes possible to utilize the incident light reflected on the surface of the metal plate 10 (in other words, the interface between the metal plate 10 and the photocatalytic layer 20) for the photocatalytic reaction by the photocatalytic compound, thereby further improving the photocatalytic effect while suppressing costs. The total thickness d from the surface of the metal plate 10 to the outermost surface of the coating layer T (=d1+d3+d4+α) is preferably 10.00 μm or less, and more preferably 7.00 μm or less.

[0078] 2A and 2B, the 60° specular gloss measured from the side where the photocatalytic layer 20 is provided, as defined in JIS Z8741:1997, is 80% or more. T is 15.00 μm or less and the 60° specular gloss is 80% or more, it can be considered that the incident light reflected on the surface of the metal plate 10 is utilized for the photocatalytic reaction by the photocatalytic compound.

[0079] 1A to 3 illustrate the case where the photocatalytic layer 20 and other layers are provided on one side of the metal plate 10, the photocatalytic layer 20 and other layers may be provided on both sides of the metal plate 10. In this case, the total thickness d from the surface of the metal plate 10 to the surface of the photocatalytic layer 20 is T The surface roughness is set to 15.00 μm or less on each surface of the coated metal sheet 1. The 60° specular gloss is also set to 80% or more on each surface of the coated metal sheet 1. Furthermore, the protective layer 50 as described above may be formed when the inorganic chemical conversion coating layer 30 described above is provided.

[0080] The coated metal sheet according to this embodiment has been described in detail above with reference to FIGS. 1A to 3.

[0081] <Method for measuring the average thickness of each layer> Here, the average thickness of each layer, including the photocatalytic layer, can be measured by observing the layer of interest from the cross-sectional direction using a microscope. As a method for preparing a sample for cross-sectional observation, known methods can be used, such as embedding the sample in resin and polishing the observation surface, FIB processing, and microtome processing. Furthermore, known devices such as SEM and TEM can be used as the type of microscope.

[0082] (About the manufacturing method of painted metal sheets) The coated metal sheet according to the present embodiment as described above can be produced by subjecting the surface of a base metal sheet to various pretreatments, such as cleaning, as necessary, and then applying a photocatalytic treatment agent for forming a photocatalyst layer, a chemical conversion treatment agent for forming a chemical conversion coating layer, or a protective treatment agent for forming a protective layer to the desired layer configuration, followed by drying and baking.

[0083] Here, various coating materials can be applied by commonly known coating methods such as roll coating, curtain flow coating, air spraying, airless spraying, dipping, bar coating, brush coating, etc. Roll coating, which is a feature of the present product and allows stable application of a thin film, is particularly preferred.

[0084] The drying and baking conditions are not particularly limited and may be set appropriately depending on the paint used, etc. [Example]

[0085] The coated metal sheet according to the present invention will be specifically described below with reference to examples and comparative examples. Note that the examples shown below are merely examples of the coated metal sheet according to the present invention, and the coated metal sheet according to the present invention is not limited to the examples below.

[0086] Eight types of metal sheets shown in Table 1 below were prepared as base metal sheets. In Table 1, the six types of metal sheets indicated as SD, ZL, GI, GL, AL, and GA are various types of plated steel sheets using steel sheets as the base material. The thickness of each metal sheet, as well as the coating composition and coating weight / specification of each plated steel sheet, are as shown in Table 1 below.

[0087] [Table 1]

[0088] Seven types of compounds shown in Table 2 below were prepared as compounds having photocatalytic activity (photocatalytic compounds). All photocatalytic compounds used were commercially available. The supported metals and average particle sizes are also shown in Table 2.

[0089] [Table 2]

[0090] <Inorganic / organic conversion coating agents> The raw materials used for the water-based paints (chemical conversion treatment agents) used to form the inorganic and organic chemical conversion treatment coatings, as well as their concentrations in the dried films, are shown in Table 3 below. The amount added was adjusted so that the concentration of each component would be the desired concentration in the dried film. Ion-exchanged water was added to adjust the solids concentration of the treatment agent to 10 mass% for the inorganic chemical conversion treatment coatings and 20 mass% for the organic chemical conversion treatment coatings. Each treatment agent was applied to the dry film thickness shown in Tables 4-1 and 4-2 below. The metal sheet was then dried in an induction heating furnace so that the temperature reached 150°C, and then water-cooled using a spray.

[0091] [Table 3]

[0092] <Photocatalytic treatment agents, protective treatment agents> The photocatalytic treatment agent used and the method for preparing the protective treatment agent will be described below. Taking storage stability into consideration, the protective treatment agent was adjusted to have a solids concentration of 8 mass %. The concentration was adjusted by diluting with n-butanol. The photocatalytic treatment agent was prepared by adding a predetermined amount of the compound shown in Table 2 to the following protective treatment agent. The solids concentration of the photocatalytic compound is as shown in Tables 4-1 and 4-2 below.

[0093] (1) Protective coating treatment agent (Si-based): Tetraethoxysilane (22.5 parts by mass), methacryloxypropyltrimethoxysilane (2.8 parts by mass), and n-butanol (26 parts by mass) were mixed and stirred at 60°C for 2 hours. While stirring this mixture, a mixture of 26% by mass of hydrochloric acid (3 parts by mass) and n-butanol (26 parts by mass) was added dropwise at a rate of 1 drop / second. The mixture was then kept stirred at 60°C for 2 hours to obtain a treatment agent. This series of operations was carried out in a nitrogen atmosphere.

[0094] (2) Protective coating treatment agent (Zr-based): Zirconium n-butoxide (34.5 parts by mass), n-butanol (11.6 parts by mass), 1,5-diaminopentane (0.5 parts by mass), and yttrium nitrate (2.8 parts by mass) were mixed and stirred for 1 hour. Glacial acetic acid (4.8 parts by mass) was then added and stirred for 40 hours. Concentrated nitric acid (0.6 parts by mass) was then added dropwise at a rate of 1 drop / second, and the mixture was stirred for 2 hours to obtain a treatment agent. This series of operations was carried out in a nitrogen atmosphere.

[0095] Using the metal sheets and photocatalytic compounds described above, coated metal sheets having the structures shown in Tables 4-1 and 4-2 below were produced by roll coating. Each layer was formed on one side of the metal sheet. For some of the coated metal sheets, a decorative finish was applied to the surface of the metal sheet to form a hairline pattern. For some of the coated metal sheets, a hot-dip galvanized bath containing 0.1 mass % Sb and 0.2 mass % Al was used, and a plated steel sheet on which a spangle pattern had been formed by adjusting the solidification rate of the hot-dip galvanized coating was used as the substrate.

[0096] The average film thickness of each layer in the coated metal sheet was measured by embedding the resulting coated metal sheet in resin, polishing the cross section, and observing the obtained observation surface under a microscope. The 60° specular gloss was measured using a gloss meter (UGV-6P manufactured by Suga Test Instruments Co., Ltd.) in accordance with JIS Z8741:1997.

[0097] The resulting coated metal sheets were evaluated from the viewpoints of antiviral properties, adhesion properties during processing, and corrosion resistance. Detailed evaluation methods are as follows.

[0098] <Antiviral> The antiviral properties were verified by measuring the virus infectivity in the following antiviral test in accordance with the antiviral standards stipulated by the Antibacterial Products Technology Council. More specifically, each coated metal plate was placed in a petri dish with the test surface facing up, and a virus suspension containing influenza A virus was dropped onto the test surface. After that, a film was placed over the coated metal plate to allow the virus suspension to adhere to the entire test surface, and the petri dish was then covered with a lid. The petri dish was left to stand for 24 hours in a room at 25°C with an illuminance of 1000 lux, simulating the interior of a typical office. After that, the virus on the film surface and the test surface was washed away, and the virus infectivity (unit: PFU / cm) in the resulting washing solution was measured. 2 The PFU (Plaque Forming Units) was measured by plaque assay.

[0099] In addition to the coated metal sheets, the same antiviral test was also carried out on each metal sheet that did not have a photocatalytic layer, and the extent to which the viral infectivity of the coated metal sheets had decreased compared to the viral infectivity of the metal sheets that did not have a photocatalytic layer was evaluated as the activity value. 2 If the activity has decreased by more than 1 × 10 2 If the activity value is 1 × 10 or more, the use of the certification seal prescribed by the Antibacterial Product Technology Council is permitted. 2 Those having the above value were judged to be acceptable. In Table 5 below, the obtained activity values ​​are shown as logarithmic values.

[0100] <Processing adhesion> The test material was subjected to 0T bending (180° bending), and the coating on the outside of the bent portion was peeled off with adhesive tape (Nichiban Cellotape (registered trademark), tape width 15 mm), and then the state of adhesion of the coating to the tape side was observed. The processing adhesion was then evaluated according to the following evaluation criteria. In this adhesion test, a pass level was 3 or higher. Specifically, a score of 4 or higher was considered to be excellent adhesion, and a score of 3 or higher was considered to be acceptable (pass level).

[0101] (Evaluation criteria) 5: No coating on the tape side 4: There are several points of coating peeling on the tape side, and the peeling length on the steel plate side is less than 5% of the total length of the processed part on one side of the test material. 3: There are several peeled spots on the tape side, and the peeled length on the steel plate side is 5% or more but less than 10% of the total length of the processed area on one side of the test material. 2: Coating peeled off on the tape side, and the peeled length on the steel plate side was 10% or more but less than 20% of the total length of the processed area on one side of the test material. 1: Coating peeled off on the tape side, and the peeled length on the steel plate side was 20% or more of the total length of the processed part on one side of the test material.

[0102] <Corrosion resistance> The end faces of the test specimens were sealed with tape and subjected to a salt spray test (SST) in accordance with JIS Z 2371 for 72 hours. After the test, the state of rust on the flat surface was observed and the corrosion resistance was evaluated according to the following criteria. A pass level was 3 or higher.

[0103] (Evaluation criteria) 5: The area where white rust has occurred is less than 1% of the total area on one side of the test material. 4: The area of ​​white rust is 1% or more but less than 5% of the total area on one side of the test material. 3: The area of ​​white rust is 5% or more but less than 10% of the total area on one side of the test material. 2: The area of ​​white rust is 10% or more but less than 30% of the total area on one side of the test material. 1: The area where white rust has occurred is 30% or more of the total area on one side of the test material.

[0104] [Table 4-1]

[0105] [Table 4-2]

[0106] The results obtained are summarized in Table 5 below. As is clear from Table 5 below, the coated metal sheets corresponding to the examples of the present invention exhibited excellent antiviral properties, adhesion during processing, and corrosion resistance, while the coated metal sheets corresponding to the comparative examples of the present invention failed the evaluation results for antiviral properties or adhesion during processing.

[0107] [Table 5]

[0108] Although the preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, the present invention is not limited to these examples. It is clear that a person skilled in the art to which the present invention pertains can conceive of various modifications and alterations within the scope of the technical ideas set forth in the claims, and it is understood that these also naturally fall within the technical scope of the present invention. [Explanation of symbols]

[0109] 1. Painted metal plate 10 metal plate 20 Photocatalytic layer (first coating layer) 30 Inorganic chemical conversion coating layer (second coating layer) 40 Organic conversion coating layer (third coating layer) 50 Protective layer (fourth coating layer)

Claims

1. A coated metal plate having a coating layer on at least one surface of the metal plate, The coating layer is located on the outermost surface of the coating layer on at least one surface of the metal plate, and contains a compound having photocatalytic activity (excluding the cases where the compound having photocatalytic activity is rutile-type titanium oxide and the case where the compound having photocatalytic activity is crystalline zirconium titanate). and a second coating layer located below the first coating layer and made of an inorganic component containing at least one element selected from the group consisting of Si and Zr, The average thickness of the first coating layer is 0.05 to 5.00 μm, The average thickness of the second coating layer is 0.10 to 5.00 μm, The total thickness from the surface of the metal plate to the outermost surface of the coating layer is 15.00 μm or less, the second coating layer further contains an inorganic component having at least one element of P or V, The coated metal sheet has a 60° specular gloss as defined in JIS Z8741:1997 of 80% or more.

2. The first coating layer further contains at least one element of Si or Zr, 2. The coated metal sheet according to claim 1, wherein the total concentration of the elements is 5 to 50 mass % in terms of silica for Si and zirconia for Zr.

3. 3. The coated metal sheet according to claim 1, wherein a ratio of an average thickness of the second coating layer to an average thickness of the first coating layer is 0.3 to 12.

0.

4. 3. The coated metal sheet according to claim 1, wherein the second coating layer contains at least one of zirconium carbonate, ammonium zirconium carbonate, potassium zirconium carbonate, sodium zirconium carbonate, or ammonium zirconium carbonate as the inorganic component containing Zr.

5. 3. The coated metal sheet according to claim 1, wherein the second coating layer contains, as the inorganic component containing P, at least one of phosphoric acid, orthophosphoric acid, metaphosphoric acid, pyrophosphoric acid, triphosphoric acid, tetraphosphoric acid, and salts thereof, or ammonium dihydrogen phosphate.

6. 3. The coated metal sheet according to claim 1, wherein the second coating layer contains, as the inorganic component containing V, at least one of ammonium metavanadate (V), potassium metavanadate (V), sodium metavanadate (V), or vanadyl sulfate (IV).

7. The coated metal sheet according to claim 1 or 2, wherein a total thickness from the surface of the metal sheet to the outermost surface of the first coating layer is 10.00 μm or less.

8. 3. The coated metal sheet according to claim 1, wherein the compound having photocatalytic activity is anatase-type titanium oxide.

9. 9. The coated metal sheet according to claim 8, wherein the anatase type titanium oxide is a metal-supported type titanium oxide supported on at least one metal selected from the group consisting of Cu and Fe.

10. 9. The coated metal sheet according to claim 8, wherein the concentration of the anatase type titanium oxide in the first coating layer is 50 to 95 mass % in terms of titania.

11. 9. The coated metal sheet according to claim 8, wherein the anatase type titanium oxide has an average particle size of 5 to 200 nm.

12. 3. The coated metal sheet according to claim 1, wherein the metal sheet is a zinc-plated steel sheet, a zinc-aluminum alloy-plated steel sheet, a zinc-aluminum-magnesium alloy-plated steel sheet, an aluminum-plated steel sheet, a zinc-nickel alloy-plated steel sheet, a zinc-iron alloy-plated steel sheet, an aluminum sheet, or a stainless steel sheet.

13. The coated metal sheet according to claim 1 or 2, wherein a hairline is present on the surface of the metal sheet along the rolling direction of the metal sheet.

14. The coated metal sheet according to claim 1 or 2, wherein a spangle pattern is present on the surface of the metal sheet.

Images