JP2000239047A - Hydrophilic photocatalytic member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a member capable of sufficiently manifesting not only hydrophilic actions but also photocatalytic actions such as antimicrobial actions and antifouling actions. SOLUTION: This member is obtained by forming a titanium oxide (TiO2) layer 2 on the surface of a glass plate 1 as a substrate and forming a silicon oxide (SiO2) film 3 as an overcoating layer on the surface of the titanium oxide (TiO2) layer 2. A soda-lime glass consisting essentially of SiO2 is used as the glass plate 1 and the titanium oxide (TiO2) layer 2 is formed by, e.g. a sputtering method. The thickness thereof is >=200 nm, more preferably >=500 nm and crystal faces (101), (112) and (211) are oriented nearly parallel to the substrate surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a hydrophilic photocatalyst member exhibiting a hydrophilic action, an antibacterial action and an antifouling action by a photocatalyst.

[0002]

_2. Description of the Related Art It has been known that when titanium oxide (TiO ₂ ) is irradiated with ultraviolet rays, a hydrophilic action, an antibacterial action and an antifouling action are exerted by the photocatalytic action of titanium oxide (TiO ₂ ).

[0003] As a prior art in which such a titanium oxide (TiO ₂ ) is applied to a substrate such as glass or ceramics, Japanese Patent Application Laid-Open Nos. 9-57912, 10-36144, 10-57817 and JP-A-10-2
There is one disclosed in Japanese Patent No. 31146. In the basic structure disclosed in these prior arts, a titanium oxide layer as a photocatalyst is formed directly or via a base film for blocking alkali on the surface of a glass substrate, and silicon oxide (SiO ₂₎ is formed on the surface of the titanium oxide layer. ) A film is formed.

The prior art described above is designed to enhance the photocatalytic action by making the silicon oxide (SiO ₂ ) film porous or providing fine irregularities on the titanium oxide (TiO ₂ ) film or glass substrate.

It is known from the Wenzel equation that a hydrophilic surface becomes more and more hydrophilic, since the surface area is increased by forming fine irregularities on the surface. However, even if fine irregularities are formed on the surface, the remarkable improvement in the antibacterial action and the antifouling action is not necessarily observed.

A proposal focusing on the orientation of the crystal plane of titanium oxide (TiO ₂ ) has been proposed in Japanese Patent Application Laid-Open No. H10-152396. This prior art relates to titanium oxide (Ti
Of the crystal planes of O ₂ ), the crystal planes selected from (001), (211), (101) and (110) are oriented in the direction perpendicular to the crystal direction, so that the antibacterial action of the photocatalyst and the antifouling effect It enhances the action, the decomposition action of organic substances, and the hydrophilic action.

[0007]

The photocatalytic action of titanium oxide (Ti) of anatase type is better than that of rutile type.
It is true that O ₂ ) is stronger, and it is therefore expected that the orientation of the crystal planes will affect photocatalysis. However, as described in the prior art mentioned above, (001), (211), (101) and (11)
When the crystal plane selected from 0) is oriented in the direction perpendicular to the crystal direction, a slight improvement in the photocatalytic action is observed, but it is not sufficient.

[0008]

According to a first aspect of the present invention, there is provided a hydrophilic photocatalyst member having a titanium oxide layer as a photocatalyst formed on a substrate surface directly or via a base film for blocking alkali. A hydrophilic photocatalyst member having an overcoat layer formed on the surface of the titanium oxide layer, wherein the titanium oxide layer has an anatase-type crystal structure, and has crystal faces (101), (112) and (211). Are oriented substantially parallel to the substrate surface. here,
That the crystal planes (101), (112) and (211) are oriented substantially parallel to the substrate surface means that a peak by X-ray diffraction can be captured.

Further, the hydrophilic photocatalyst member according to claim 2 has a configuration in which the crystal plane (200) is similarly oriented in addition to the above-mentioned crystal plane.

A hydrophilic photocatalyst member according to claim 3 is
A hydrophilic photocatalyst member in which a titanium oxide layer as a photocatalyst is formed directly on the surface of a substrate or via an underlayer for blocking alkali, and an overcoat layer is formed on the surface of the titanium oxide layer, wherein the titanium oxide 200n layer thickness
m or more, and the crystallite size of titanium oxide is 10 nm.
At least 50 nm.

In order to improve the photocatalytic action, it is preferable that the titanium oxide layer has an anatase type crystal structure. In particular, the crystal planes (101), (112) and (211) are almost equal to the substrate surface. By being oriented in parallel, the photocatalytic action is sufficiently exhibited. When the thickness of the titanium oxide layer is 200 nm or more, the orientation of the crystal planes (101), (112), and (211) becomes remarkable. Further, the crystal plane (200) is also preferably oriented substantially parallel to the substrate surface. The more preferable thickness of the titanium oxide layer is 500 nm or more. on the other hand,
Even if the thickness of the titanium oxide layer is 200 nm or more, the above crystal plane orientation cannot be obtained when the substrate temperature at the time of forming the titanium oxide layer is about 230 ° C. or less. This is because when the substrate temperature is set to about 230 ° C. or less, the growth of the titanium oxide crystal is not sufficient, and the crystallite size becomes less than 10 nm. As a result, if the orientation of the crystal plane is not performed, Conceivable.

Further, in order to improve the hydrophilicity, it is preferable that the surface average roughness (Ra) of the outermost surface of the member is 0.5 to 25 nm. That is, when the surface area is increased by r times by forming fine irregularities on the surface, the contact angle with water when the surface is smooth is θ, and the contact angle with water when the irregularities are formed is θ ′. From the Wenzel equation, cos θ ′ = r
cos θ (90 °>θ> θ ′) holds. For example, if irregularities are formed on the surface of a member having a contact angle of 30 ° with water when the surface is smooth and the surface area is increased by a factor of 1.1, cos θ ′ = 1.1 cos30 ° = 0.935 from the above equation. From this, θ ′ = 17.7 °. Similarly, when the surface area is increased by a factor of 1.15, θ ′ becomes 5.2 °.
When θ is 90 ° or more, that is, when the surface is hydrophobic (water repellent), θ ′ increases as the surface area increases. That is, by forming fine irregularities on the surface, the hydrophilic surface becomes more and more hydrophilic, and the hydrophobic surface becomes more and more hydrophobic.

In order to make the outermost surface of the member have the above-mentioned average surface roughness, the average surface roughness (Ra) of the titanium oxide layer should be 0.5 to 0.5%.
It may be 25 nm. In this case, the unevenness of the titanium oxide layer is transferred to the overcoat layer as it is, so that the surface average roughness (Ra) of the outermost surface of the member becomes 0.5 to 25 nm. If the surface average roughness (Ra) is smaller than 0.5 nm or larger than 25 nm, the long-term stability of hydrophilicity is not preferred. The average interval (Sm) of the irregularities is 4
~ 300 nm is preferred. 300 even if smaller than 4 nm
Even if it is larger than nm, the long-term stability of hydrophilic performance is low, which is not preferable. The more preferable range of the average interval (Sm) of the unevenness is 5 to 150 nm. Within this range, the long-term stability of hydrophilic performance is even better. Here, the surface average roughness (R
a), the average interval (Sm) of the irregularities is JIS B 060
1 (1994), and can be calculated from a cross-sectional curve observed and measured using an electron microscope (for example, H-600 manufactured by Hitachi, Ltd.).

In the present invention, the overcoat layer on the photocatalytic film is indispensable for hydrophilicity when no light is irradiated. The overcoat layer is at least one metal oxide selected from silicon oxide, aluminum oxide, titanium oxide, zirconium oxide, and cerium oxide (excluding only one kind of titanium oxide), and preferably contains silicon oxide in an amount of 80 wt% or more. It is a thin film.

The overcoat layer can be formed by a known method. For example, a sol-gel method (for example, Yuji Yamamoto, Kanichi Kamiya, Saio Sakuhana, Journal of the Ceramic Society of Japan, 90, 328-333 (1
982)), liquid phase deposition method (for example, Japanese Patent Publication No. 1-59210).
No. 4-13301), vacuum film forming method (vacuum deposition, sputtering), baking method, spray coating (for example, JP-A-53-124523, JP-A-56-967).
No. 49), CVD method (for example, JP-A-55-90441).
JP-A-1-201046, JP-A-5-20884
No. 9) is an example.

The average thickness of the overcoat layer is 0.1.
1-50 nm is preferred. When the average thickness is less than 0.1 nm, the effect of improving hydrophilicity is not remarkable. When the average thickness is more than 50 nm, irregularities on the surface of the titanium oxide layer tend to be buried, and the effect of improving hydrophilicity by ultraviolet irradiation is hardly recognized. It is not preferable.

Preferably, the overcoat layer is a porous body. When the overcoat layer is porous, in particular, porous having a pore volume of 1 to 50%, the ability to retain moisture on the surface is increased, and the hydrophilicity is further improved, which is preferable.

[0018] The porous overcoat layer can be formed in various ways. For example, it can be formed using a sol-gel method.
In the coating liquid for forming an overcoat, at least one organic polymer compound selected from the group consisting of polyethylene glycol, polypropylene glycol, and polyvinyl alcohol is added, and a solution obtained by dissolving them is treated with the photocatalyst formed. It is obtained by applying and drying on a substrate, and further heating at 350 to 650 ° C. for 5 minutes to 2 hours to decompose the added organic polymer compound.

The hydrophilic photocatalyst member according to the present invention can be applied to, for example, mirrors and window glasses for automobiles.

[0020]

Embodiments of the present invention will be described below with reference to the accompanying drawings. Here, FIGS. 1A and 1B are enlarged cross-sectional views of the hydrophilic photocatalyst member according to the present invention, respectively, and FIG. 2 is a view illustrating a crystal plane of titanium oxide (TiO ₂ ).

In the embodiment shown in FIG. 2A, a titanium oxide (TiO ₂ ) layer 2 is formed on the surface of a glass plate 1 as a substrate for a hydrophilic photocatalyst member, and this titanium oxide (TiO ₂ ) layer is formed. Silicon oxide (SiO ₂ ) as an overcoat layer on the surface of
The film 3 is formed. In the embodiment shown in (b),
Between the glass plate 1 and the titanium oxide (TiO ₂ ) layer 2, a base film 4 for preventing the leaching of alkali such as Na from the glass plate 1 is interposed.

The glass plate 1 is made of soda lime glass containing SiO ₂ as a main component, and a titanium oxide (TiO ₂ ) layer 2
Is formed by a conventionally known method such as a sol-gel method, a liquid phase deposition method, a vacuum film formation method, a baking method, a spray coating method, a CVD method, and a sputtering method, and has a thickness of 200 nm or more. Average roughness (Ra)
Is 0.5 to 25 nm. The titanium oxide (TiO ₂ ) layer 2 has an anatase type crystal structure.

On the other hand, the silicon oxide (SiO ₂ ) film 3 is formed by sputtering and has a thickness of 0.1 to 100 nm. Since the silicon oxide (SiO ₂₎ film 3 is formed on the titanium oxide (TiO ₂₎ layer 2, unevenness of titanium oxide (TiO ₂₎ layer 2 is transferred as it is, silicon oxide (SiO ₂₎ film The surface average roughness (Ra) of the surface of No. 3 is also 0.
It is 5 to 25 nm. In addition, the average interval of irregularities (S
It is appropriate for m) to be in the range of 4 to 300 nm.

Titanium oxide (TiO ₂ ) has a crystallite size of 10
In the range of not less than nm and not more than 50 nm, the hydrophilic action, antibacterial action and antifouling action by the photocatalyst are ensured. If the crystallite size is smaller than 10 nm, the photocatalytic activity is not sufficient. On the other hand, when the crystallite size is larger than 50 nm, the transparency of the thin film is reduced, and the film has a high haze ratio, which is not preferable.

Here, anatase type titanium oxide (Ti
O ₂ ) has its crystal planes (101), (112), (200), (211) and (204) oriented substantially parallel to the substrate surface. Each crystal plane is shown in FIG.

[0026] Figure 3 is titanium oxide (TiO ₂₎ layer, for example, DC magnetron sputtering (pressure: 3 mTorr, Temperature: 350 ° C.) titanium oxide when formed by the (TiO ₂₎
X-ray diffraction graph showing relationship between layer thickness and crystal plane, FIG.
The substrate processing temperature and titanium oxide (thickness: 500 nm) X-ray diffraction graph showing the relationship between the crystal planes of FIG. 5 is a crystal plane when changing the film thickness and the deposition temperature of the titanium oxide (TiO ₂₎ FIG. 9 is an X-ray diffraction graph showing the relationship, and is further shown in the following (Table 1).
Table 4 summarizes the embodiment of FIG. 5 and a comparative example.

Example 1 The antifogging article shown in Example 1 was produced in the following manner. [Formation of Base Film] In order to prevent alkali elution from the glass plate to the titanium oxide film, SiO _{2 was formed} by RF magnetron sputtering (target SiO ₂ ). Oxygen gas 5sccm and argon gas 60scc
m, a gas pressure of 3 mTorr, a target input power of 2 kW, and a thickness of 3 mm, 10 × 10 cm by an in-line type RF magnetron sputtering apparatus.
An underlayer of SiO ₂ was formed on soda-lime glass of □. The number of passes of the substrate transfer was adjusted to form a base film (SiO ₂ ) having a thickness of 50 nm. The film thickness of the underlayer (SiO ₂ ) was measured and confirmed using a stylus-type step meter.

[Formation of Titanium Oxide Film] A titanium oxide layer was formed on the glass plate on which the above-mentioned SiO ₂ underlayer was formed in the following manner. Gas (oxygen) 50 sc by in-line type DC magnetron sputtering device (target: Ti)
cm, gas pressure 3mTorr, target input power 3kW
Under the above conditions, the glass plate was heated to about 350 ° C. by a heater in a vacuum device chamber to form a titanium oxide film. By adjusting the number of passes of the substrate transfer, a film thickness of 500
An nm-thick titanium oxide film was formed. Titanium oxide (TiO ₂ )
Was measured and confirmed using a stylus-type step meter.

[Formation of Overcoat Layer] An SiO ₂ film as an overcoat layer was formed on the glass plate on which the above-mentioned underlayer film and titanium oxide film had been formed in the following manner. Using a mixed gas of 5 sccm of oxygen gas and 60 sccm of argon, under the conditions of a gas pressure of 3 mTorr and a target input power of 2 kW, the base film and the titanium oxide film are formed by an in-line RF magnetron sputtering apparatus (target SiO ₂ ). An SiO ₂ film as an overcoat layer was formed on the glass plate thus obtained. The number of passes of the substrate transfer was adjusted to form an overcoat layer having a thickness of 10 nm. The thickness of the overcoat layer was measured and confirmed using a stylus-type step meter. Thereby, the glass plate / base film (Si
O ₂ ) (50 nm) / titanium oxide layer (TiO ₂ ) (500
nm) / overcoat layer (SiO ₂ ) (10 nm) to obtain a hydrophilic photocatalyst member. The sample thus obtained is designated as A.

[Evaluation of Photocatalytic Activity] The photocatalytic activity was measured by the following triolein decomposition test. The film surface side of the sample cut out in 70 mm □, triolein (chemical formula (C _{17
H 33 COO) 3 C 3 H} 5) was 2.5mg dropping and coating, compared triolein residual ratio Evaluation of the photocatalytic activity. The sample was irradiated with ultraviolet light having an intensity of 3 mW / cm ² for 20 hours from the film surface side with black light on the sample surface.
After irradiation with ultraviolet light, the sample weight was measured, and the residual ratio of triolein was obtained, and this was used as an index of photocatalytic activity. It can be said that the smaller the residual ratio of triolein, the higher the photocatalytic activity. The triolein residual ratio (%) was calculated by the following equation. Triolein residual rate = ((z−x) / (y−x)) × 1
Here, x: weight of sample only (g) y: weight of sample coated with triolein before ultraviolet irradiation (g) z: weight (g) of sample coated with triolein after ultraviolet irradiation

[Measurement of Surface Roughness and Average Spacing of Roughness]
The arithmetic average roughness (Ra) (nm) and the average interval (Sm) (nm) of the unevenness of the titanium oxide layer were measured by AFM (atomic force microscope).

[Calculation of average crystallite size] The crystallite size of titanium oxide was calculated by the following method. From the integrated width of the peak for each orientation plane obtained by X-ray diffraction measurement,
The crystallite size was calculated from the formula of Cerrer. Scherrer's equation ε = λ / (β · cos θ) ε = crystallite size (Å) λ = measured X-ray wavelength (Å) β = peak integration width (radian) θ = Bragg angle of diffraction line (radian) )

[Evaluation of Hydrophilicity] The sample A was kept in a room where it was not exposed to direct sunlight but was indirectly brightened by sunlight and where people constantly came in and out. And the degree of cloudiness when breath was sprayed was evaluated (breath test). That is, the sample immediately after the surface is cleaned does not fog even when breath is blown, but when left indoors, dirt components in the air are adsorbed on the sample surface and become cloudy by the breath test. The time from the start of indoor standing until the start of fogging (antifogging maintenance time) was used as an index of antifogging maintenance. It can be said that the larger this value is, the higher the antifogging maintenance property is. The antifogging maintenance of these samples was evaluated according to the following (Table 1).

[0034]

[Table 1]

Further, a sample having a reduced anti-fogging property due to standing in a room (having fogging in the breath test) was subjected to xenon lamp light (ultraviolet intensity: 0.5 mW / cm ² : UV intensity meter UVR-2 manufactured by Topcon Corporation). / UD-36) was continuously irradiated for 30 minutes, and the magnitude of the decrease in the contact angle of the water droplet (the recovery amount of the contact angle of the water droplet) was used as an index of the anti-fogging recovery property.
In addition, an ultraviolet ray of 0.5 mW / cm ² (340 to 395 n
m) The irradiation intensity is about 20 times the ultraviolet intensity contained in direct sunlight from outdoor sunlight at 35 ° N latitude at noon in winter, fine weather, and noon.
%. If the ultraviolet ray reduces the contact angle of the water droplet and restores the hydrophilicity, it can be said that the sample has a very good antifogging recovery property. Using a contact angle meter ("CA-DT" manufactured by Kyowa Interface Science Co., Ltd.), the contact angle with respect to a 0.4 mg water droplet before and after irradiation with light for 30 minutes was measured. The water droplet contact angle ratio defined by the value of (contact angle after light irradiation for 30 minutes) / (contact angle before light irradiation) was determined and evaluated according to the following (Table 2). It can be said that the smaller the water droplet contact angle ratio, the better the anti-fogging recovery property by light irradiation.

[0036]

[Table 2]

The results of various evaluations of Sample A are shown in Table 3.
And (Table 4). Sample A was found to be excellent in antifogging maintenance and antifogging recovery.

[0038]

[Table 3]

[0039]

[Table 4]

(Example 2) In the same manner as in Example 1, a glass plate / underlayer (SiO ₂ ) (50 nm) / titanium oxide layer (TiO ₂ ) (1000 nm) / overcoat layer (Si)
O ₂ ) (10 nm). The sample thus obtained is designated as B. Various antifogging evaluation results of Sample B are shown in (Table 3) and (Table 4).

(Comparative Example 1) Glass plate / underlayer (SiO ₂ )
(50 nm) / titanium oxide layer (TiO ₂ ) (500 nm)
Was formed. The substrate was not heated during the formation of the titanium oxide layer, but was formed at room temperature. The sample thus obtained is designated as C. Various antifogging evaluation results of Sample C are shown in (Table 3) and (Table 4).

(Comparative Example 2) Glass plate / underlayer (SiO ₂ )
(50 nm) / titanium oxide layer (TiO ₂ ) (200 nm)
Was formed. The sample thus obtained is designated as D. Various antifogging evaluation results of Sample D are shown in (Table 3) and (Table 4).

Comparative Example 3 In the same manner as in Comparative Example 2, a glass plate / underlayer (SiO ₂ ) (50 nm) / titanium oxide layer (TiO ₂ ) (50 nm) was formed. The sample thus obtained is referred to as E. The results of evaluating various antifogging properties of Sample E are shown in (Table 3) and (Table 4).

(Comparative Example 4) Glass plate / underlayer film (SiO ₂ )
(50 nm) / titanium oxide layer (TiO ₂ ) (1000 n)
m) was formed. The substrate was not heated during the formation of the titanium oxide layer, but was formed at room temperature. The sample thus obtained is designated as F. The results of evaluating various antifogging properties of Sample F are shown in (Table 3) and (Table 4).

Comparative Example 5 A glass plate / underlayer (SiO ₂ ) (50 nm) / titanium oxide layer (TiO ₂ ) was prepared in the same manner as in Example 1 except that no overcoat layer was formed.
(500 nm). The sample thus obtained is referred to as G. Various antifogging evaluation results of Sample G are shown in (Table 3) and (Table 4).

Comparative Example 6 A glass plate / underlayer (SiO ₂ ) (50 nm) / titanium oxide layer (TiO ₂ ) was prepared in the same manner as in Example 2 except that no overcoat layer was formed.
(1000 nm). The sample thus obtained is designated as H. Various antifogging evaluation results of Sample H are shown in (Table 3) and (Table 4).

Comparative Example 7 In the same manner as in Example 1, a glass plate / underlayer (SiO ₂ ) (50 nm) / titanium oxide layer (TiO ₂ ) (500 nm) / overcoat layer (Si)
O ₂ ) (10 nm). The substrate was not heated during the formation of the titanium oxide layer, but was formed at room temperature. The sample thus obtained is designated as J. Various antifogging evaluation results of Sample J are shown in (Table 3) and (Table 4).

From the above figures and tables, in order to sufficiently exert the effect of the photocatalyst, at least the crystal faces (101), (11)
It is necessary that (2) and (211) are oriented substantially parallel to the substrate surface, and for this purpose, the thickness of the titanium oxide (TiO ₂ ) layer is 200 nm or more, preferably 5 nm or more.
It can be seen that it is necessary to set the substrate temperature (film formation temperature) to about 230 ° C. or more at 00 nm or more.

[0049]

As described above, in the hydrophilic photocatalyst member according to the first aspect, the titanium oxide layer as the photocatalyst is formed on the surface of the base material directly or through the base film for blocking alkali. A hydrophilic photocatalyst member having an overcoat layer formed on a surface of a titanium layer, wherein the titanium oxide layer has an anatase-type crystal structure, and has a crystal face (101),
(112) and (211) are oriented substantially parallel to the surface of the base material, and the hydrophilic photocatalyst member according to claim 2 is provided directly on the base material surface or via a base film for blocking alkali. A titanium oxide layer as a photocatalyst is formed on the surface of the titanium oxide layer, and an overcoat layer is formed on the surface of the titanium oxide layer.
And the crystallite size of titanium oxide is 1
Since it is 0 nm or more and 50 nm or less, not only a hydrophilic action, but also a photocatalytic action such as an antibacterial action and an antifouling action is sufficiently exhibited.

[Brief description of the drawings]

FIGS. 1A and 1B are enlarged cross-sectional views of a hydrophilic photocatalyst member according to the present invention, respectively.

FIG. 2 is a diagram illustrating a crystal plane of titanium oxide (TiO ₂ ).

FIG. 3 is an X-ray diffraction graph showing the relationship between the thickness of a titanium oxide (TiO ₂ ) layer and the crystal plane.

FIG. 4 is an X-ray diffraction graph showing a relationship between a substrate processing temperature and a crystal plane.

FIG. 5 is an X-ray diffraction graph showing the relationship between the film thickness and the crystal plane by changing the film formation temperature.

[Explanation of symbols]

1 ... glass plate, 2 ... a titanium oxide (TiO ₂₎ layer, 3 ... silicon oxide (SiO ₂₎ film, 4 ... base film.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C09K 3/00 C09K 3/00 S (72) Inventor Ogino Etsuo 3-5 Doshomachi, Chuo-ku, Osaka-shi, Osaka No. 11 Nippon Sheet Glass Co., Ltd. (72) Inventor Kazuhiro Doshita 3-5-11 Doshomachi, Chuo-ku, Osaka City, Osaka Inside Nippon Sheet Glass Co., Ltd.

Claims (8)

[Claims] 1. A hydrophilic photocatalyst member comprising a titanium oxide layer as a photocatalyst formed directly on the surface of a base material or through an alkali blocking layer, and an overcoat layer formed on the surface of the titanium oxide layer. The titanium oxide layer has an anatase-type crystal structure and has crystal faces (101), (11).
2) and (211) are oriented substantially parallel to the substrate surface. 2. The hydrophilic photocatalyst member according to claim 1, wherein the crystal plane (200) is oriented substantially parallel to the substrate surface. 3. A hydrophilic photocatalyst member comprising a titanium oxide layer as a photocatalyst formed directly on a surface of a base material or via an alkali-shielding base film, and an overcoat layer formed on the surface of the titanium oxide layer. A thickness of the titanium oxide layer is 200 nm or more, and a crystallite size of the titanium oxide is 10 nm or more and 50 nm or less. 4. The hydrophilic photocatalyst member according to claim 1, wherein the titanium oxide layer or the overcoat layer has a surface average roughness (Ra) of 0.5 to 2.
A hydrophilic photocatalyst member having a thickness of 5 nm. 5. The hydrophilic photocatalyst member according to claim 1, wherein the overcoat layer comprises silicon oxide, aluminum oxide, zirconium oxide,
A hydrophilic photocatalyst member comprising at least one selected from a mixture of cerium oxide, titanium oxide, and another oxide. 6. The hydrophilic photocatalyst member according to claim 1, wherein the thickness of the overcoat layer is 0.1 to 50 nm. 7. The hydrophilic photocatalyst member according to claim 1, wherein the overcoat layer contains silicon oxide in an amount of 80 wt% or more. 8. The hydrophilic photocatalyst member according to claim 1, wherein the hydrophilic member is located between the back surface of the base material, between the base material and the titanium oxide layer, or between the base film and the titanium oxide layer. A hydrophilic photocatalyst member, which is a mirror having a metal thin film formed thereon.