Member having photocatalytic activity and multilayered glass

The present invention relates to a member having a photocatalyst layer formed on its surface and a double glazing incorporating this member.

Photocatalysts such as anatase-type titanium oxide are known to exhibit antifouling effect, antibacterial property and hydrophilicity that decompose organic substances by irradiation with ultraviolet rays. Recently, a photocatalyst that exerts a catalytic function by visible light has also attracted attention. In order to form the above-mentioned photocatalyst layer on the surface of a member such as glass, a vacuum film forming method such as sputtering or thin film deposition or a vacuum film forming method is often used.

Patent Document 1, Patent Document 2, Patent Document 3 and Patent Document 4 have proposed to provide a base layer between a base material and a photocatalyst layer when forming a photocatalyst layer on the surface of a base material such as glass. Patent Document 1 describes that when a medium made of a photocatalyst composition is formed on the surface of a glass base material, the glass base material and the photocatalyst composition (medium) are used in order to prevent the function of the medium from being deteriorated by the alkali eluted from the glass. It is disclosed that a barrier layer is provided between them, and it is proposed to use zirconium oxide, particularly amorphous zirconium oxide, as the barrier layer. Patent Document 2 discloses that a photocatalyst layer is formed by interposing a base film on a base material, and in particular, zirconium oxide is used as the base film and titanium oxide is used as the photocatalyst layer. Patent Document 3 describes that a metal oxide layer such as zirconium oxide is interposed between the base material (aluminum) and the photocatalyst layer, and the metal oxide layer suppresses the diffusion of oxygen from the photocatalyst layer to the base material. Is disclosed. Patent Document 4 mentions zirconium oxide as a photocatalytic substance, and discloses the contents of forming a titanium oxide layer on the outside of the zirconium oxide.

Further, there are Patent Documents 5 and 6 as prior arts that mention the relationship between the film thickness and the optical characteristics of a film in which zirconium oxide and titanium oxide are laminated. Patent Document 5 describes SnO with a thickness of 10 nm or less as an alkali diffusion prevention layer.₂And ZrO₂Is mentioned, TiO₂20 nm or less is mentioned, and it is described that it is necessary to reduce the thickness of the coating film in order to make the article transparent. Patent Document 6 discloses that a high-temperature stable cubic or orthorhombic zirconium oxide layer is formed between a substrate and a titanium oxide layer, and further, in automobile applications, the thickness of the photocatalyst layer. It is stated that should be visible.

<patcit num="1"><text>Japanese Unexamined Patent Publication No. 9-227167</text></patcit><patcit num="2"><text>Japanese Unexamined Patent Publication No. 10-66878</text></patcit><patcit num="3"><text>Japanese Unexamined Patent Publication No. 2000-312830</text></patcit><patcit num="4"><text>Japanese Unexamined Patent Publication No. 2001-205094</text></patcit><patcit num="5"><text>Japanese Patent Application Laid-Open No. 2000-513695, p. 12, line 8</text></patcit><patcit num="6"><text>PCT International Publication (WO 02/40417), page 10, line 9</text></patcit>

<p> When the photocatalyst layer is formed by the methods described in Documents 1 to 5, it may not function as a photocatalyst, or it does not function as a photocatalyst unless the thickness of the photocatalyst layer is increased, and the reflectance of the article increases. In some cases, it may be difficult to achieve both favorable reflectance and color tone and photocatalytic activity due to the appearance of interference colors.</p><p> Further, as disclosed in Patent Document 6, a photocatalytic layer (TiO)₂), A crystalline zirconium oxide layer can be provided to form a photocatalytic layer with excellent photocatalytic activity, but it is necessary to form a high-temperature stable cubic or orthorhombic zirconium oxide layer. In some cases, a resin having low heat resistance cannot be used as the substrate. In addition, since it is technically difficult to uniformly heat a large-sized substrate, it is difficult to obtain a large-sized photocatalytic member for construction, and there is a problem that color tone becomes uneven. ..</p><p> Further, it is known that the double glazing is provided with a heat ray reflecting film (low emission film: Low-E film) on the indoor side surface of the outdoor side glass plate, and the glass plate provided with this heat ray reflecting film is provided. Has a greenish tint, and there is a problem in the degree of freedom of the tint.</p>

<p> In order to solve the above problems, the member having a photocatalytic function according to the present invention is provided with an oxide containing at least one of silicon and tin, an oxynitride, and a peeling prevention layer containing nitride as a main component on the surface of the transparent base material. A member having a photocatalytic function in which a photocatalytic layer is formed on the peeling prevention layer via a crystalline base layer, and the thickness of the crystalline base layer is 2 nm or more and 40 nm or less, preferably 3 nm or more and 20 nm or less. The thickness of the photocatalyst layer was 2 nm or more and 15 nm or less, preferably 3 nm or more and 10 nm or less.</p><p> Amorphous silicon oxide can be exemplified as the peeling prevention layer, zirconium oxide can be exemplified as the crystalline base layer, and crystalline titanium oxide can be exemplified as the photocatalyst layer. In particular, the crystalline base layer is preferably a monoclinic zirconium oxide crystal.</p><p> That is, a photocatalyst layer (TiO) having the same film thickness.₂), When the cross-sectional structure of the photocatalytic function was observed with an electron microscope, it was found that the difference was in the crystallinity of the photocatalytic layer. That is, the photocatalytic layer (TiO) in which the columnar particle structure is clearly and continuously formed from the interface with the base material to the surface of the layer.₂) Exhibits a remarkable photocatalytic effect, but a columnar particle structure is not observed near the interface with the substrate, and a photocatalytic layer having an amorphous layer (hereinafter referred to as a dead layer) does not exhibit a sufficient photocatalytic effect.</p><p> Here, the dead layer is a layer in which the characteristic of amorphous (amorphous) is strongly exhibited, and the electron diffraction image is observed as a halo pattern. If it is not a dead layer, a diffraction spot is observed.</p><p> Further, in the case where the above dead layer is substantially absent, a particle structure is continuously formed from the base layer to the photocatalyst layer, so that the particle structure passes through the gaps between these particle structures (columnar structure) and chloride ions are emitted from the surface. Ions and moisture with a small ionic radius, such as, may diffuse toward the glass substrate (base material). When such diffusion molecules reach the glass substrate, anions such as chloride ions react with alkaline ions such as sodium existing in the glass substrate to form salts, which may cause the film to peel off or become a defect. In some cases.</p><p> The present inventors have made the present invention based on the following findings. That is, if the photocatalyst layer is formed through the base layer that promotes the growth of crystal particles of the photocatalyst, the appearance of the dead layer can be suppressed, and a peeling prevention layer is provided between the base layer and the glass substrate. For example, the peeling of the film from the glass substrate and the occurrence of defects can be suppressed, the deterioration of the photocatalyst performance can be suppressed, and the photocatalyst can be prepared by using a layer containing monochromatic zirconium oxide crystals as the base layer. The effect of promoting the growth of crystal particles is further enhanced, and further, by limiting the thickness of the crystalline base layer and the thickness of the photocatalyst layer to specific ranges, the reflectance is low, the reflection color is light blue, and the reflection is performed. Since uneven rate and uneven color tone are eliminated, it can be preferably applied to large-area architectural glass that emphasizes a specific design such as exhilaration.</p><p> Among architectural glasses, it is conceivable to apply the above-mentioned member having a photocatalytic function as an outdoor side glass plate of double glazing. In this case, a peeling prevention layer containing oxides containing at least one of silicon and tin, an oxynitride, and a nitride as main components is provided on the outdoor side surface of the outdoor side glass plate, and is provided on the peeling prevention layer. A photocatalyst layer having a thickness of 2 nm or more and 15 nm or less, preferably 3 nm or more and 5 nm or less is formed through a crystalline base layer having a thickness of 2 nm or more and 25 nm or less, preferably 3 nm or more and 5 nm or less, and is formed on the indoor surface of the outdoor glass plate. The structure is such that a heat ray reflecting film is formed.</p><p> In the above-mentioned member having a photocatalytic function or double glazing, the thickness of the peeling prevention layer is 2 nm to 200 nm, preferably 5 nm to 100 nm. If the thickness of the peeling prevention layer is thinner than 2 nm, the effect of suppressing film peeling and the occurrence of defects is not sufficient, which is not preferable. Further, even if this is thicker than 200 nm, the effect of suppressing the film peeling and the occurrence of defects is not significantly improved. Therefore, from an economical point of view, the upper limit of the thickness of the peeling prevention layer is preferably 200 nm. When the thickness of the peeling prevention layer is thicker than 5 nm, the effect of blocking water is enhanced, and the generation of water-soluble salts at the interface between the substrate and the film is completely suppressed, which is more preferable. Further, since this effect is sufficiently exhibited when the thickness of the peeling prevention layer is 100 nm or less, the upper limit of the more preferable thickness of the peeling prevention layer is 100 nm. However, when a peeling prevention layer having a refractive index significantly different from that of the substrate is selected, it is preferable to make the layer as thin as possible so as not to cause a change in color tone.</p><p> The peeling prevention layer blocks ions and moisture having a small ionic radius such as chloride ions from the surface, prevents these ions and molecules from reaching the glass substrate (base material), and generates water-soluble reactive salts. Since it is prevented, it is possible to suppress the peeling of the base layer from the substrate, which occurs when it dissolves in water. When a glass substrate produced by the float method is selected as the base material, the tin alteration layer or the amorphous tin oxide layer formed on the contact surface of the glass substrate with the tin bath should be used as the peeling prevention layer. Can be done.</p><p> Further, in the present invention, the underlayer and the photocatalyst layer are made of crystalline metal oxide or metal oxynitride, and at least one of the distances between oxygen atoms in the crystals constituting the underlayer is a photocatalyst. It is preferably close to one of the distances between oxygen atoms in the crystals that make up the layer. If the combination of the base layer and the photocatalyst layer satisfying this condition, when the photocatalyst layer is formed on the base layer, the crystalline photocatalyst layer is likely to grow immediately with the oxygen atom as a common portion. Focusing on the spacing of oxygen atoms, monoclinic zirconium oxide and anatase-type titanium oxide are similar in some parts (in the range of 90 to 110%), and a monoclinic crystalline zirconium compound is used as the base layer. If selected, it is considered that anatase-type titanium oxide crystals are likely to be formed on the anatase-type titanium oxide crystals. As the base layer, in addition to the monoclinic zirconium oxide, zirconium oxide to which a small amount of nitrogen, tin or carbon is added, or zirconium oxynitride is preferably used. Further, as the photocatalyst layer, in addition to the anatase-type titanium oxide, titanium oxide to which a small amount of nitrogen, tin or carbon is added, or titanium oxynitride is preferably used.</p><p> The electron diffraction image obtained by irradiating the layer cross section of the zirconium oxide monoclinic crystal, which is preferable as the base layer, from the orthogonal direction includes a diffraction image from the (111) plane or the (-111) plane. 111) The plane spacing of the oriented planes is 2.6 to 3.0 Å, and the (-111) plane spacing of the oriented planes is 3.0 to 3.4 Å. Zirconium oxide with a surface spacing outside this range has a large film stress because strain is generated in the crystal, and the film is likely to peel off. In addition, the oxygen position on the crystal plane shifts due to strain, and the consistency between the oxygen position and the oxide constituting the photocatalyst layer such as titanium oxide becomes low, so that preferable crystal growth of the photocatalyst layer cannot be observed.</p><p> Further, as an electron beam diffraction image obtained by irradiating the layer cross section of anatase-type titanium oxide, which is preferable as a photocatalyst layer, from a direction orthogonal to the layer, there is a diffraction image from the (101) plane, and the plane spacing of the (101) orientation plane. Is 3.3 to 3.7 Å. Titanium oxide with a surface spacing outside this range has a large film stress because strain is generated in the crystal, and the film is likely to peel off. In addition, the oxygen position on the crystal plane shifts due to strain, and the consistency between the oxygen position and the oxide constituting the underlying layer such as zirconium oxide becomes low, so that preferable crystal growth of titanium oxide cannot be observed.</p><p> The method for forming the base layer and the photocatalyst layer may be any method such as a liquid phase method (solgel method, liquid phase precipitation method) and a vapor phase method (blasting method, vacuum vapor deposition method, CVD method), and the base film may be used. Although the effect of improving the crystallinity of the photocatalyst layer is observed, since it is accompanied by crystal growth, a vapor phase method such as a sputtering method or a vapor deposition method, which is particularly effective in the present invention, is more suitable.</p><p> Further, by doping the photocatalyst layer with a metal, the generation of carriers can be promoted and the photocatalytic effect can be enhanced. As the dope metal, Zn, Mo, Fe, etc. are suitable because they have a high effect of improving photocatalytic activity. For Zn and Mo, the addition amount is preferably 0.1% by mass or more and 1% by mass or less, and more preferably 0.2% by mass or more and 0.5% by mass or less. For Fe, the content in the photocatalyst layer should be 0.001% by mass or more and 0.5% by mass or less. The reason for limiting this is that if the amount added is too small, the effect is too small, and if it is too large, the crystal structure of the photocatalyst is disturbed and the recombination center is generated, resulting in a decrease in photocatalytic activity.</p><p> The hydrophilic effect can be enhanced by forming a hydrophilic thin film on the surface of the photocatalyst layer. The hydrophilic thin film is preferably at least one oxide selected from the group consisting of silicon oxide, zirconium oxide, germanium oxide, and aluminum oxide. Of these, silicon oxide is more preferably used from the viewpoint of hydrophilicity improving effect and durability. The hydrophilic thin film is preferably porous. By being porous, not only the water retention effect is enhanced and the hydrophilicity maintenance performance is enhanced, but also active species such as active oxygen generated on the surface of the photocatalyst layer by ultraviolet irradiation can reach the surface of the article, so that the photocatalyst layer This is because the photocatalytic activity of the above is not significantly impaired.</p><p> As a method for forming a porous hydrophilic thin film, a liquid phase method (sol-gel method, liquid phase precipitation method) or a gas phase method (sputtering method, vacuum deposition method, CVD method) is used. A porous thin film can be easily prepared by applying the generally known sol-gel method, but it is easier to prepare a porous thin film by adding an organic polymer or a higher alcohol to the raw material liquid of the sol-gel method. Can be obtained. In the vapor phase method such as the sputtering method, the film formation conditions are adjusted so as to increase the dangling bonds of the oxide, such as increasing the gas pressure during sputtering and reducing the amount of oxygen in the gas. A thin film can be produced.</p><p> The thickness of the hydrophilic thin film is preferably 1 nm or more and 30 nm or less. If it is thinner than 1 nm, hydrophilicity is not sufficiently imparted, and if it is thicker than 30 nm, the photocatalytic activity of the photocatalytic layer is impaired, which is not preferable. Further, a more preferable range of this thickness is 1 nm or more and 20 nm or less. In this range, the hydrophilicity maintenance performance when not exposed to light is high.</p>

<p> As described above, according to the present invention, when forming a photocatalyst layer on the surface of a base material, a crystalline base layer is provided, and the photocatalyst layer formed on the base layer is directly formed into a photocatalyst crystal. Is made to grow continuously to the surface, and a peeling prevention layer is provided between the base material and the base layer to suppress the occurrence of film peeling and defects. High photocatalytic activity for all parts such as glass plates for DNA analysis, glass substrates for DNA analysis, information portable equipment, sanitary equipment, medical equipment, electronic equipment, biological / medical inspection chips, materials for hydrogen / oxygen generators, etc. The material to have can be provided. In particular, it is possible to provide an article having a film structure that comprehensively balances a certain optical feature, a small variation thereof, and a function of a photocatalyst.</p><p> Further, according to the present invention, by keeping the thickness of the crystalline base layer and the photocatalyst layer within a predetermined thickness, the reflected color tone can be made blue, the commercial value can be enhanced, and the double glazing can be obtained. Is expected to be applied.</p>

FIG. 1 is a cross-sectional view of a member having a photocatalytic function according to the present invention. FIG. 2 is a cross-sectional view of the double glazing according to the present invention. [Fig. 3] ZrO₂Layer and TiO₂SiO with a layer film thickness of 10 nm₂The figure which shows the change of the color tone of transmitted light when the film thickness of a layer is changed at a pitch of 10 nm. [Fig. 4] ZrO₂Layer and TiO₂SiO with a layer film thickness of 10 nm₂The figure which shows the change of the color tone of the reflected light when the film thickness of a layer is changed at a pitch of 10 nm. [Fig. 5] SiO₂Layer and ZrO₂TiO with a layer film thickness of 10 nm₂The figure which shows the visible light reflectance when the film thickness of a layer is changed at a pitch of 5 nm. [Fig. 6] SiO₂Layer and TiO₂ZrO with a layer film thickness of 10 nm₂The figure which shows the visible light reflectance when the film thickness of a layer is changed at a pitch of 5 nm. [Fig. 7] SiO₂Layer and ZrO₂TiO with a layer film thickness of 10 nm₂The figure which shows the visible light reflectance of the double glazing (with Low-E film) when the film thickness of a layer is changed at a pitch of 5 nm. [Fig. 8] SiO₂Layer and TiO₂ZrO with a layer film thickness of 10 nm₂The figure which shows the visible light reflectance of the double glazing (with Low-E film) when the film thickness of a layer is changed at a pitch of 5 nm. [Fig. 9] SiO₂Layer and ZrO₂TiO with a layer film thickness of 10 nm₂The figure which shows the change of the chromaticity coordinate-to-coordinate distance (D) when the film thickness of a layer is changed at a pitch of 5 nm. [Fig. 10] Fig. 10 is a diagram showing a change in reflected color tone showing a range in which the distance (D) between chromaticity coordinates is 3.5 or less corresponding to Fig. 9. [Fig. 11] SiO₂Layer and TiO₂ZrO with a layer film thickness of 10 nm₂The figure which shows the change of the chromaticity coordinate-to-coordinate distance (D) when the film thickness of a layer is changed at a pitch of 5 nm. FIG. 12 is a diagram showing a change in reflected color tone showing a range in which the chromaticity coordinate-to-coordinate distance (D) is 3.5 or less corresponding to FIG. [Fig. 13] SiO₂Layer and ZrO₂TiO with a layer film thickness of 10 nm₂The figure which shows the change of the chromaticity coordinate-to-coordinate distance (D) of the double glazing when the film thickness of a layer is changed at a pitch of 5 nm. FIG. 14 is a diagram showing a change in reflected color tone showing a range in which the chromaticity coordinate-to-coordinate distance (D) is 3.5 or less corresponding to FIG. [Fig. 15] SiO₂Layer and TiO₂ZrO with a layer film thickness of 10 nm₂The figure which shows the change of the chromaticity coordinate-to-coordinate distance (D) of the double glazing when the film thickness of a layer is changed at a pitch of 5 nm. FIG. 16 is a diagram showing a change in reflected color tone showing a range in which the chromaticity coordinate-to-coordinate distance (D) is 3.5 or less corresponding to FIG. [Fig. 17] SiO₂Layer, ZrO₂Layer, TiO₂The figure which shows the change of the color tone when the double glazing is made by using the glass plate which made all the film thickness of a layer equal.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Here, FIG. 1 is a typical cross-sectional view of a member having a photocatalytic function according to the present invention, and FIG. 2 is a cross-sectional view of a double glazing having a member having a photocatalytic function as an outdoor side glass plate.

In the member having a photocatalytic function shown in FIG. 1, SiO is used as the peeling prevention layer 1 on the surface of the transparent substrate 1 such as a glass plate.₂A layer is provided, and ZrO is provided as a crystalline base layer 2 on the peeling prevention layer 1.₂A layer is provided, and TiO is provided as a photocatalyst layer 3 via the crystalline base layer 2.₂Layers are provided. The thickness of each layer is SiO₂Layer is 2nm or more and 200nm or less, ZrO₂Layer is 2 nm or more and 40 nm or less, TiO₂The layer is 2 nm or more and 15 nm or less.

In the double glazing shown in FIG. 2, the outdoor side glass plate 10 and the indoor side glass plate 20 are arranged to face each other so as to form a dense space between them via the spacer 30. Then, SiO is used as the peeling prevention layer 1 on the outdoor side surface of the outdoor side glass plate 10.₂A layer is provided, and ZrO is provided as a crystalline base layer 2 on the peeling prevention layer 1.₂A layer is provided, and TiO is provided as a photocatalyst layer 3 via the crystalline base layer 2.₂Layers are provided. Further, a low emissivity film 4 (Low-E film) is formed on the indoor side surface of the outdoor side glass plate 10.

Figures 3 and 4 show ZrO₂And TiO₂SiO with a film thickness of 10 nm₂It is a figure which shows the change of the color tone of the transmitted light and the reflected light when the film thickness of is changed at a pitch of 10 nm, and from these figures, SiO which has substantially the same refractive index as glass.₂It can be seen that the color tone hardly changes even if the film thickness is changed, and the change in color tone increases as the difference in the refractive index from the glass increases, and the rate of change increases as the film thickness increases. Here, the color tone (a *, b *) was calculated from the spectrum obtained from the spectrophotometer based on CIE1976UCS.

5 to 8 are diagrams showing the relationship between the film thickness of each layer and the visible light reflectance (R), and FIG. 5 is a diagram showing the relationship between SiO and SiO.₂Layer and ZrO₂TiO with a layer film thickness of 10 nm₂Figure 6 shows the visible light reflectance when the film thickness of the layer is changed at a pitch of 5 nm.₂Layer and TiO₂ZrO with a layer film thickness of 10 nm₂Figure 7 shows the visible light reflectance when the film thickness of the layer is changed at a pitch of 5 nm.₂Layer and ZrO₂TiO with a layer film thickness of 10 nm₂Figure 8 shows the visible light reflectance of double glazing (with Low-E film) when the film thickness of the layer is changed at a pitch of 5 nm.₂Layer and TiO₂ZrO with a layer film thickness of 10 nm₂The visible light reflectance of double glazing (with Low-E film) when the film thickness of the layer is changed at a pitch of 5 nm is shown. Here, the visible light reflectance was calculated from the results measured by a spectrophotometer based on JIS R3106. From these figures, the visible light reflectance is TiO₂Layer and ZrO₂It can be seen that the film thickness increases when the film thickness is 50 to 60 nm, and the visible light reflectance decreases when the film thickness is smaller or larger than this range. The visible light reflectance (R) is 20% or less, preferably 15% or less.

9 to 16 are diagrams showing the distance between chromaticity coordinates (D) and the corresponding change in reflected color tone, and FIG. 9 is a diagram showing SiO.₂Layer and ZrO₂TiO with a layer film thickness of 10 nm₂The figure showing the change of the chromaticity coordinate distance (D) when the film thickness of the layer is changed at a pitch of 5 nm, FIG. 10 shows the range in which the chromaticity coordinate distance (D) is 3.5 or less corresponding to FIG. The figure which shows the change of the reflected color tone, FIG. 11 shows SiO₂Layer and TiO₂ZrO with a layer film thickness of 10 nm₂The change in the chromaticity coordinate distance (D) when the layer thickness is changed at a pitch of 5 nm is shown, and FIG. 12 shows the range in which the chromaticity coordinate distance (D) is 3.5 or less corresponding to FIG. The figure which shows the change of the reflected color tone, FIG. 13 is SiO₂Layer and ZrO₂TiO with a layer film thickness of 10 nm₂The change in the chromaticity coordinate distance (D) of the double glazing when the layer thickness is changed at a pitch of 5 nm is shown. FIG. 14 shows the chromaticity coordinate distance (D) of 3.5 or less corresponding to FIG. The figure showing the change of the reflected color tone showing the range of, FIG. 15 is SiO₂Layer and TiO₂ZrO with a layer film thickness of 10 nm₂The change in the chromaticity coordinate distance (D) of the double glazing when the layer thickness is changed at a pitch of 5 nm is shown. FIG. 16 shows the change in the chromaticity coordinate distance (D) corresponding to FIG. It is a figure which shows the change of the reflection color tone which shows the range of. When D is 3.5 or less, color unevenness does not increase even if the film thickness fluctuates during manufacturing, which is preferable in terms of quality control. Here, it is clear that the magnitude of the D value indicates the ease of color change, but the present invention has found the film thickness range of each layer so that the value can be suppressed within a certain range. Is. Here, the distance between the chromaticity coordinates indicates the distance between the chromaticity coordinates before the film thickness is changed and when the film thickness is changed by 5 nm. The calculation formula is shown below.<img file="JP4362476B2_D0001.tif" />

The above is summarized in (Table 1) below. From this (Table 1), the color change rate and reflectance of a single film single plate (a photocatalyst layer formed only on one side of a glass plate) Considering (blue range), visible light reflectance, and hydrophilicity, ZrO₂For the layer, 2 nm to 40 nm, preferably 3 nm to 20 nm, TiO₂The layer is 2 nm to 15 nm, preferably 3 nm to 10 nm, and the double glazing (with Low-E film) using the above single glass is ZrO.₂For layers, 2 nm to 25 nm, preferably 3 nm to 5 nm, TiO₂It can be said that the layer is 2 nm to 15 nm, preferably 3 nm to 5 nm. The photocatalytic activity (hydrophilicity) is evaluated by using a black lamp (center wavelength 365 nm) as a light source and illuminance of 1 mW / cm.²Then, the contact angle of water 60 minutes after UV irradiation was measured to evaluate hydrophilicity.

<img file="JP4362476B2_D0002.tif" /><img file="JP4362476B2_D0003.tif" />

In addition, Fig. 17 shows SiO₂Layer, ZrO₂Layer, TiO₂It is a figure which shows the change of the color tone when the double glazing is made by using the glass plate which made all the film thickness of a layer equal. In FIG. 17, G indicates glass and / indicates that layers are laminated. AKM5 is G / SiO₂(5nm) / ZrO₂(5nm) / TiO₂(5nm) AKM10 is G / SiO₂(10nm) / ZrO₂(10nm) / TiO₂(10nm) AKM15 is G / SiO₂(15nm) / ZrO₂(15nm) / TiO₂(15nm) AKM20 is G / SiO₂(20nm) / ZrO₂(20nm) / TiO₂(20nm) In addition, the composition of the low emissivity film 4 is Low-E = G / ZnO (35.2nm) / Ag (6.3nm) / ZnO (85.2nm) / Ag (12.1nm) / ZnO (35.2nm) Is. From FIG. 17, as compared with the Low-E film alone, in the double glazing in which the photocatalyst layer of the present application is formed on the first surface (outdoor side surface) of the outdoor side glass plate, the reflection color observed from the outdoor side is green. It can be seen that the color has changed to blue.