JP2002234105A - Hydrophilic member and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transparent member of which the surface is made hydrophilic corresponding to weak light of an indoor illumination level even by a small amount of titanium oxide. SOLUTION: The hydrophilic member consists of a base material and the film formed on the surface of the base material, and the film comprises particles of photocatalytic titanium oxide and particles of a second photocatalytic material other than titanium oxide. At least a part of the particles of photocatalytic titanium oxide and at least a part of the particles of the second photocatalytic material are bonded without forming a solid solution. At least a part of the particles of the photocatalytic titanium oxide is present in a state capable of coming into contact with moisture in the open air and the potential of the lower end of the conductive zone of the second photocatalytic material is more positive than 0 V in terms of paired standard hydrogen electrode potential at the time of pH=7 and the potential of the upper end of the valence electron zone of the second photocatalytic material is more positive than +2.7 V in terms of paired standard hydrogen electrode potential at the time of pH=7. Light with a wavelength capable of optically exciting the second photocatalytic material can arrive at least at one of the photocatalytic titanium oxide and the second photocatalytic material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a hydrophilic member.

[0002]

2. Description of the Related Art Various applications utilizing the hydrophilizing ability of a photocatalyst have been proposed. For example, if the surface of a member is in a state of not more than 10 ° in terms of a contact angle with water, moisture in the air, Even if the steam condenses, the tendency of condensed water to form a uniform water film without forming individual water droplets becomes remarkable. Therefore, the tendency that light scattering fogging does not occur on the surface becomes remarkable. Similarly, when windowpanes, vehicle rearview mirrors, vehicle windshields, eyeglass lenses, helmet shields, etc. are exposed to rain or splashes, high visibility and visibility can be achieved without forming discrete and unsightly water droplets. Ensuring vehicle and traffic safety,
The effect of improving the efficiency of various tasks and activities is dramatically improved. Further, the surface of the member is converted into a contact angle with water,
If the temperature is 0 ° or less, both the urban dust, combustion products such as carbon black contained in exhaust gas of automobiles, hydrophobic contaminants such as oils and fats, sealant eluting components, and inorganic clay contaminants adhere. It is difficult to remove, and even if it adheres, it can be easily dropped by rainfall or washing with water. The photoinduced hydrophilization phenomenon in the photocatalyst is 1) generation of electrons and holes by photoexcitation, and 2) generated holes react with oxygen atoms of the lattice to generate oxygen defects on the surface. 3) A mechanism has been considered in which moisture in the atmosphere is adsorbed on the oxygen-deficient portion and stabilized.

[0003]

When a member having a photocatalyst formed on its surface is used for daily indoor use,
The light source that can usually be expected is indoor lighting such as a fluorescent lamp or an incandescent light bulb, and the ultraviolet illuminance thereof is very small, 10 μW / cm ² or less. Even when titanium oxide, which is considered to be the most stable and has high photocatalytic activity, is used as a photocatalyst, it is insufficiently hydrophilized in a weak indoor light irradiation environment.

On the other hand, in order to obtain a large hydrophilizing ability of titanium oxide, it is preferable to increase the thickness of titanium oxide. However, most photocatalysts represented by titanium oxide are high refractive index substances. Photocatalyst layer μ
If it is attempted to form a film having a thickness of m order or more, there is a problem that cloudiness, iris color, and the like are likely to be exhibited, and the transparency and appearance of the member are impaired.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a member capable of causing a surface hydrophilic reaction at a practical level in response to weak light of an indoor lighting level even with a small amount of titanium oxide. With the goal.

[0006]

The present invention comprises a substrate and a film formed on the surface of the substrate, wherein the film comprises a layer containing photocatalytic titanium oxide particles formed on the surface of the substrate. ,
Further, an island-shaped portion or a domain-shaped portion made of a second photocatalytic material other than titanium oxide is further formed thereon, and at least a portion of the photocatalytic titanium oxide particles and at least a portion of the second photocatalyst are joined. And at least a part of the layer containing the photocatalytic titanium oxide exists in a state where it can come into contact with moisture in the outside air, and the potential at the lower end of the conduction band of the second photocatalytic material is pH = 7. Is more positive than 0 V in terms of the standard hydrogen electrode potential at the time of, the potential at the upper end of the valence band of the second photocatalytic material,
+2 in terms of standard hydrogen electrode potential when pH = 7.
A hydrophilic member which is more positive than 7V and is capable of reaching at least one of the photocatalytic titanium oxide and the second photocatalytic material with light having a wavelength capable of photoexciting the photocatalytic material. I do.

In the hydrophilic member of the present invention, since the second photocatalyst material is formed in the form of islands or domains having a particle size of 50 nm or less, coloring and light scattering are not observed, and the transparency is high. Further, in the photocatalyst member of the present invention, even in a small amount, a hydrophilic reaction on the surface can be caused at a practical level in response to weak light at an indoor lighting level. This is because, by joining the photocatalytic titanium oxide and the second photocatalyst, charge separation is promoted very well, and at least a part of the titanium oxide exists in a state where it can come into contact with moisture in the outside air. This is because the water adsorption reaction to the oxygen deficiency generating section is promoted.

The mechanism for promoting the charge separation is considered as follows. In the hydrophilic member of the present invention, one of the photocatalysts is titanium oxide, and the other is a second photocatalyst other than titanium oxide in which the lower end of the conduction band and the upper end of the valence band are more positive than titanium oxide, When titanium and the second photocatalyst are joined, electrons generated in the conduction band by photoexcitation and holes generated in the valence band move between different photocatalysts if the Gibbs free energy decreases. It is possible.

For example, with respect to the hydrophilic member having the energy structure as shown in FIG. 1 according to the present invention, when both the titanium oxide and the second photocatalyst are photoexcited, the electrons generated in the conduction band of the titanium oxide become the second. The holes that move to the conduction band of the photocatalytic material and are generated in the valence band of the second photocatalyst can move to the valence band of titanium oxide. The holes that have moved to the titanium oxide side react with the lattice oxygen of the titanium oxide itself to generate oxygen vacancies having a high affinity for water and become hydrophilic, while the electrons that have moved to the second photocatalyst are oxygen in the air. Reacts with to generate superoxide anion and is released to the outside world. In the member of the present invention, the holes generated in the second photocatalyst effectively act on the hydrophilicity of the surface of the titanium oxide particles, and assist, so that even a small amount of material can be used on the surface according to the weak light of the indoor lighting level. The hydrophilization reaction can occur at a practical level.

One of the photocatalysts is titanium oxide particles,
FIG. 2 shows a case where the other one using a second photocatalyst which can be excited by visible light having a wavelength of 400 nm or more is irradiated with visible light. When this composite member is irradiated with visible light, titanium oxide particles cannot be excited by visible light having a wavelength of 400 nm or more, and can only excite the second photocatalyst,
The holes photoexcited by the second photocatalyst move to the titanium oxide side. The probability of recombination due to the separation of the electron-hole pairs is extremely low, and the hydrophilization reaction on the surface of the titanium oxide particles is promoted. Further, as shown in FIG. 3, even when only titanium oxide is excited, the generated holes are efficiently collected on the surface of the titanium oxide particles without recombination with the electrons, and the hydrophilization reaction on the surface of the titanium oxide particles occurs. Promoted.

In a preferred embodiment of the present invention, a layer containing photocatalytic titanium oxide particles is formed on the surface of the substrate, and an island-like layer made of a second photocatalytic material other than titanium oxide having a particle size of 10 nm or less is further formed thereon. A portion or a domain-like portion is formed on the layer containing the titanium oxide, and the photocatalytic titanium oxide particles are bonded to a second photocatalytic material other than the titanium oxide. The order titanium oxide and the second photocatalyst is improved charge separation efficiency is bonded, highly hydrophilic surface by irradiation with a small amount of weak white fluorescent lamp 1 .mu.W / cm ² in terms of UV illumination in the titanium oxide It is possible to Further, in the hydrophilic member in the preferred embodiment,
Since the particles of the second photocatalyst are fine and the amount of titanium oxide used can be reduced, the transparency is high.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION As the crystal structure of titanium oxide of a hydrophilic member according to the present invention, anatase type, rutile type and brookite type can be suitably used. In addition, since the increase in surface hydroxyl groups due to light irradiation occurs on the surface of the titanium oxide particles, it is desirable that at least a part of the titanium oxide particles exist in a state where the titanium oxide particles can come into contact with moisture in the outside air. More preferably, at least a part of the titanium oxide particles is exposed to the outside air.

If the particle size of the second photocatalytic material other than the titanium oxide increases, the transparency of the surface layer is impaired by optical scattering caused by these particles. Means that the particle size of the second photocatalytic material is 50
Desirably, it is not more than nm.

In the hydrophilic member of the present invention, charge transfer occurs at the junction between the titanium oxide particles and the second photocatalyst, and the charge separation efficiency is improved. Therefore, in order to improve the photo-induced hydrophilicity of the photocatalytic material, it is desirable to increase the contact point between titanium oxide and the second photocatalytic material. That is, the second photocatalyst is preferably fine particles, and in a preferred embodiment of the present invention, the second photocatalytic material has a particle size of 10 nm on the layer containing the photocatalytic titanium oxide.
It is distributed in the form of fine islands or domains of nm or less.

In the hydrophilic member of the present invention, the hydrophilicity of the surface of the titanium oxide particles is greatly promoted and the change in the wettability of the surface of the second photocatalytic material is small. Has a suitable compounding ratio. That is, a structure that can keep the exposed area of the titanium oxide portion contributing to the change in wettability is desirable. When the ratio of the second photocatalytic material to titanium oxide on the surface of the hydrophilic member is smaller than 0.5% in the area ratio measured by X-ray photoelectron spectroscopy, the second photocatalytic material is used. No effect of improving the hydrophilicity is observed. Conversely, if the proportion occupied by the second photocatalytic material is greater than 50% in the area ratio measured by X-ray photoelectron spectroscopy, the exposed area occupied by the titanium oxide itself becomes smaller, so that the hydrophilicity due to the second photocatalytic material becomes smaller. Since the exposed area of the titanium oxide is smaller than the effect of improving the hydrophilization property, the hydrophilization is inhibited, and as a result, the hydrophilization property of the surface deteriorates. That is, in a preferred embodiment of the present invention, the proportion of the surface occupied by the second photocatalytic material is in the range of 0.5 to 50% in terms of the area ratio measured by X-ray photoelectron spectroscopy. Can be preferably used.

In the present invention, as the second photocatalyst,
The potential at the lower end of the conduction band is more positive than 0 V when converted to the standard hydrogen electrode potential when pH = 7, and the standard hydrogen electrode potential when the upper potential of the valence band is pH = 7. Tungsten oxide, tungstate, tin oxide, and the like can be suitably used as a material that is more positive than +2.7 V in terms of.

The second photocatalytic material has an amorphous structure which can be dispersed more uniformly and has less grain boundaries which hinder the transfer of electrons and holes, as compared to a material having a structure agglomerated with crystallization. Is more suitable for increasing the sensitivity of the photo-induced hydrophilicity. When the second photocatalytic material is amorphous, the heat treatment for solidifying the titanium oxide surface is at a low temperature, so that a solid solution cannot be generated between the titanium oxide and the second photocatalyst. In a solid solution, an impurity level is formed in the titanium oxide or the second photocatalyst, and this level becomes a recombination center of an electron-hole pair, which significantly lowers the charge separation efficiency. The photocatalytic material is preferably in an amorphous state without formation of a solid solution.

As the second photocatalyst, amorphous tungsten oxide or tungstate is particularly preferable. The band gaps of amorphous tungsten oxide and ammonium tungstate are both 3.1 eV, which is narrower than the band gap of titanium oxide of 3.2 eV. It is possible to excite the pair. .

In order to maintain or enhance hydrophilicity in a dark place, the film containing the titanium oxide and the second photocatalyst further contains a metal oxide capable of adsorbing more chemically adsorbed water than titanium oxide. You may. By doing this,
In a room, even when there is no light irradiation at night, a highly hydrophilic state is maintained, and antifogging properties are exhibited both day and night.

Further, the metal oxide capable of adsorbing more chemically adsorbed water than titanium oxide is further layered on the film containing titanium oxide and the second photocatalyst in a thickness of 1 nm to 100 nm. It may be formed. Even in such a form, even when there is no light irradiation in the room at night, the highly hydrophilic state is maintained, and the antifogging property is exhibited regardless of day and night.

If the thickness of the metal oxide capable of adsorbing a large amount of the chemically adsorbed water is in the range of 1 nm to 100 nm, the titanium oxide is in a state where it can be brought into contact with moisture in the outside air through the open pores of the metal oxide. And a hydrophilization reaction accompanying photoexcitation can be advanced.

As the metal oxide capable of adsorbing more chemically adsorbed water than titanium oxide, a metal compound having at least one bond selected from the group consisting of a siloxane bond, a borosiloxane bond, and an aluminosilicate bond is preferably used. it can.

A preferred specific configuration of the present invention will be described below with reference to the drawings. In one embodiment of the present invention, as shown in FIG. 4, a layer containing titanium oxide is formed on a substrate, on which islands or domains formed of a second photocatalyst are formed by the oxidation. It is bonded to a layer containing titanium. At least a part of the titanium oxide is exposed to the outside air and can come into contact with moisture in the outside air. When the titanium oxide and the second photocatalyst are excited, electrons generated in the titanium oxide flow to the second photocatalyst, while holes reach the surface of the titanium oxide. Since the photoexcited holes are collected on the surface of the titanium oxide without recombination with the electrons, the hydrophilization reaction in the titanium oxide is remarkably promoted.

In another embodiment of the present invention, as shown in FIG. 5, in order to maintain or enhance the hydrophilicity in a dark place, the surface of the hydrophilic member in FIG. An island portion or a domain portion made of a metal oxide capable of adsorbing a large amount of adsorbed water may be formed.

In another embodiment of the present invention, as shown in FIG. 6, a layer containing titanium oxide is formed on a base material, and an island portion or domain portion made of a second photocatalyst is formed thereon. And a layer made of a metal oxide capable of adsorbing more chemically adsorbed water than titanium oxide is formed thereon. In this case, the thickness of the metal oxide is 1n
In the range of m to 100 nm, as described above, since water molecules can pass through the open pores of the metal oxide, the titanium oxide is always in a state capable of contacting moisture in the outside air,
The part of titanium oxide can be easily made hydrophilic by light irradiation.

In another embodiment of the present invention, as shown in FIG. 7, a mixed layer containing titanium oxide and a metal oxide capable of adsorbing more chemically adsorbed water than titanium oxide is formed on a substrate. Further, an island portion or a domain portion made of a second photocatalyst is bonded to the mixed layer. Also in this embodiment, the hydrophilicity in a dark place can be maintained or enhanced.

Hereinafter, a method for producing a hydrophilic member having a preferred specific structure according to the present invention will be described. Starting materials for titanium oxide include, for example, amorphous titania sol, crystalline titania sol, tetramethoxytitanium, tetraethoxytitanium, tetraisopropoxytitanium, tetra-n-propoxytitanium, tetrabutoxytitanium, titanium chelate, acetylacetone titanium, tetrachloride A raw material containing at least one selected from the group consisting of titanium, titanium sulfate, and titanium hydroxide can be used.

As a starting material of the second photocatalyst, for example, at least one selected from the group consisting of metal salts, colloids, alkoxides, chelate compounds and acetate compounds containing metal elements constituting the photocatalyst other than titanium oxide The raw material containing can be used. In particular,
When the second photocatalyst is a tungsten oxide or a tungstate, a liquid in which tungstic acid is dissolved in aqueous ammonia can be easily produced as a starting material. When the second photocatalyst is tin oxide, an aqueous colloidal solution of an amorphous oxide is generally commercially available as a starting material, and is preferably used as a raw material for forming an island-like portion or a domain-like portion. I can do it.

The starting material of a metal oxide capable of adsorbing more chemically adsorbed water than titanium oxide is selected, for example, from the group consisting of metal salts, colloids, alkoxides, chelate compounds and acetate compounds containing this metal. Raw materials containing at least one type can be used. For example, when the metal oxide capable of adsorbing more chemically adsorbed water than titanium oxide is a compound having a siloxane bond, as a starting material, for example, silica, silicone, alkyl silicate, alkali silicate, acrylic silicone, etc. are preferably used. it can.

As shown in FIG. 4, a member is produced in which a layer of titanium oxide is formed on a base material, and an island or domain made of a second photocatalyst is joined thereon. As a method, for example, there is the following method. After the starting material of titanium oxide is applied to the substrate, a thin film of titanium oxide is formed by drying or baking, and then the starting material of the second photocatalyst is applied thereon, followed by drying or baking.

As shown in FIG. 5, titanium oxide is formed on a substrate, and furthermore, island-like or domain-like portions composed of a second photocatalyst, and more chemically adsorbed water than titanium oxide are adsorbed thereon. As a method of manufacturing a member to which an island-shaped portion or a domain-shaped portion made of a metal oxide that can be bonded is manufactured, for example, the following method is available. After the starting material of titanium oxide is applied to the substrate, a thin film of titanium oxide is formed by drying or baking. Further, a coating agent containing a starting material for the second photocatalyst and a starting material for the metal oxide is applied thereon, followed by drying or baking to produce a member as shown in FIG. Further, after forming the titanium oxide thin film, the starting material of the second photocatalyst may be applied, followed by drying or baking, and thereafter, the starting material of the metal oxide may be applied, followed by drying or baking. . Further, after forming the titanium oxide thin film, the starting material of the metal oxide may be applied and then dried or baked, and then the starting material of the second photocatalyst may be applied and then dried or baked. .

As shown in FIG. 6, a titanium oxide layer is formed on a base material, and an island or domain formed of a second photocatalyst is bonded to the titanium oxide layer. As a method of manufacturing a member on which a metal oxide capable of adsorbing more chemically adsorbed water than titanium oxide is formed, for example, the following method is available. After the starting material of titanium oxide is applied to the substrate, a thin film of titanium oxide is formed by drying or baking. Further, after the starting material of the second photocatalyst is applied onto the titanium oxide, drying or baking is performed. After that, the starting material containing the metal oxide is further applied thereon, and then drying or baking is performed.
Can be manufactured.

As shown in FIG. 7, a mixed layer containing titanium oxide and a metal oxide capable of adsorbing more chemically adsorbed water than titanium oxide is formed on a base material, and a mixed layer comprising a second photocatalyst is formed thereon. As a method of manufacturing a member in which an island portion or a domain portion is joined to the mixed layer, for example, there is the following method. After a coating agent containing a starting material of titanium oxide and a starting material of metal oxide is applied to a substrate, a mixed layer containing titanium oxide and metal oxide is formed by drying or baking. Further, a starting material for the second photocatalyst is applied thereon, followed by drying or baking, whereby a member as shown in FIG. 7 can be manufactured.

In any of the above embodiments, as a method of applying the coating liquid, spin coating, flow coating, dip coating, spray coating, roll coating, or the like can be suitably used. For example, when the spin coating method is selected as the coating method of the coating liquid, the ratio of the second photocatalytic material to the surface can be controlled by the rotation speed of the substrate and the concentration of the raw material solution. In addition to the above-mentioned wet synthesis method, a sputtering method, a CVD method, a plasma CVD method,
An ion plating method, an MBE method, or the like may be used.

In a preferred embodiment of the present invention, a titanium oxide thin film is formed on a base material, and further, an island portion or a domain portion made of tungsten oxide or tungstate is formed on the titanium oxide film. Are joined. Starting materials for tungsten oxide or tungstate include ammonium tungstate, tungstic acid, a sol in which tungsten oxide particles are suspended, pentaethoxytungsten, pentamethoxytungsten, pentapropoxytungsten, pentabutoxytungsten, tungsten chelate, acetate tungsten, A coating solution containing at least one tungsten compound selected from the group consisting of tungsten sulfate, tungsten chloride, and tungsten hydroxide can be used. When the starting material of tungsten oxide or tungstate is heated and baked on titanium oxide, if high-temperature treatment is performed, each component of titanium oxide and tungsten oxide diffuses in a solid phase to form a solid solution. It is not preferable for the reaction to proceed. For this reason,
The temperature at which the starting material of tungsten oxide or tungstate is baked is preferably in the range of 20 ° C. to 500 ° C. when the starting material is ammonium tungstate.

In a further preferred aspect of the present invention, a titanium oxide thin film is formed on a base material, and an island portion or a domain portion made of tungstate or amorphous tungsten oxide is further formed on the titanium oxide thin film. It has a joined structure. As described above, tungstate or amorphous titanium oxide that can be produced by low-temperature heat treatment is more uniformly dispersible than crystallized tungsten oxide, and inhibits the movement of electrons and holes. Since there are few grain boundaries, the charge separation efficiency of electron-hole pairs is high. If the starting material is ammonium tungstate, a suitable heat treatment is in the range of 20C to 350C.

In order to excite the titanium oxide and the second photocatalyst according to the present invention, the wavelength is from 300 nm to 450 nm.
The light in the range described above can be suitably used. In general, when sunlight from the outdoors is blocked, light emitted from a fluorescent lamp, an incandescent lamp, or the like to an article installed on an indoor wall has an integrated illuminance of 0.3 to 450 nm in a wavelength range of 300 nm to 450 nm. 1 to
It is estimated to be 10 μW / cm ² .

The hydrophilic member of the present invention preferably has a surface contact angle of 5 ° with light from a fluorescent lamp or an incandescent lamp.
It is highly hydrophilic up to the following and exhibits antifogging, antifouling and self-cleaning effects.

The hydrophilic member of the present invention is irradiated with light from a mercury lamp, a xenon lamp, a mercury-xenon lamp, a halogen lamp, a metal halide lamp, etc., which has a high light intensity, and sunlight and sunlight entering through a window. It is needless to say that when the light is excited by the scattered light, the above-described anti-fogging, anti-fouling and self-cleaning effects are exhibited.

In the present invention, a member having a structure in which a titanium oxide thin film is formed on a base material, and an island-shaped or domain-shaped portion made of amorphous tungsten oxide or tungstate is bonded to the titanium oxide. Is
Surprisingly, even when irradiated with a weak fluorescent lamp of 1 μW / cm ² in terms of ultraviolet illuminance, the surface can be highly hydrophilized to 5 degrees or less in terms of water contact angle.
The hydrophilic member in the present invention can exhibit anti-fogging, drip-proof, and self-cleaning effects in a room with a small amount of ultraviolet light even if the amount of titanium oxide used is small. In addition, since the hydrophilic member is substantially transparent and has no interference color, its design is not impaired even if it is coated on any building exterior material, interior material or other indoor member.

[0041]

EXAMPLES Example 1 A titanium oxide coating agent having a solid content of 10% (Nippon Soda, N
DH510C) was formed on a silica-coated glass by dip coating. Dip coating was performed at a pulling rate of 15 cm / min, and the coated film was baked in an electric furnace at 500 ° C. for 30 minutes. This process was repeated twice to produce a photocatalytic titanium oxide thin film having a thickness of about 200 nm. A liquid in which tungstic acid was dissolved in 25% aqueous ammonia was coated on the thin film by spin coating. By changing the concentration of tungstic acid used at this time, a plurality of thin films having different loading amounts of the photocatalytic tungsten oxide on the titanium oxide were obtained. The # 1 sample was a film of photocatalytic titanium oxide alone not coated with tungstic acid, and the # 2 sample was 0.5% solid content ratio of tungstic acid to the total weight of the solution, and # 3
The sample was formed such that the concentration of tungstic acid was 1.0%, and the # 4 sample was formed such that the concentration of tungstic acid was 2.0%. The spin coating was performed at a rotation speed of 1500 revolutions per minute for 10 seconds, and the coated film was baked in an electric furnace at 300 ° C. for 30 minutes. As a result of measuring the ratio of tungsten atoms to titanium atoms on the surface by X-ray photoelectron spectroscopy, # 1 sample was 0%, # 2 sample was 10%, and # 3 sample was
20% and # 4 samples were 40%. As a result of evaluating the crystal system of tungsten oxide on the surface by X-ray diffraction, it was found that the tungsten oxide was amorphous photocatalytic tungsten oxide. When the surface structure was observed with an atomic force microscope, the samples # 2, # 3, and # 4 showed almost no difference from the sample # 1 of titanium oxide alone. This suggests a structure in which tungsten is distributed in the form of islands or domains on the titanium oxide thin film.

The contact angle of water on the surface of the prepared thin film is stable
After storage in a dark place, irradiate with white fluorescent light.
The change in the contact angle of the surface with water was measured. White fluorescent light
Uses 10W (Toshiba Lighting Tech, FL10N)
The UV illuminance is measured at the UV illuminometer (C)
10μW / cm with Shio Electric, UVR-2)^TwoAnd 3μW / cm
^TwoIt was set to be. The contact angle with water is a contact angle measuring instrument
(Kyowa Interface Science, CA-X150)
It was determined by dropping a water drop from a syringe.

FIG. 8 shows the change in the contact angle with water when the UV illuminance is 10 μW / cm ² . Photocatalytic titanium oxide simple substance #
One sample was hydrophilized only up to 12 degrees in terms of the contact angle with water, but an island or domain made of photocatalytic tungsten oxide was joined to a photocatalytic material titanium oxide thin film. Samples # 4 to # 4 had higher sensitivity to hydrophilization than # 1 sample of titanium oxide alone, and were highly hydrophilized to 0 ° in terms of the contact angle with water. FIG. 9 shows the results when the UV illuminance was 3 μW / cm ² , whereas the titanium oxide alone # 1 sample hardly hydrophilized.
The # 2 sample in which the ratio of tungsten atoms to titanium atoms on the surface was 10% and the # 3 sample in which the ratio was 20% were highly hydrophilized to a contact angle with water of 5 ° or less. Although the hydrophilicity was observed in the # 4 sample in which the ratio of tungsten atoms on the surface was 40%, the rate of hydrophilization was slower than in the # 2 and # 3 samples, and the contact angle with water was reduced to 8 degrees or less. Did not decrease.

Example 2 A titanium oxide coating agent having a solid content of 10% (Nippon Soda, N
DH510C) was formed on a silica-coated glass by dip coating. The manufacturing method is the same as that of the first embodiment.
A liquid in which tungstic acid was dissolved in 25% aqueous ammonia was coated on the thin film by spin coating. Regarding the concentration of tungstic acid used at this time, the # 5 sample was a film of a photocatalytic titanium oxide alone not coated with tungstic acid, and the # 6 sample was a sample in which the concentration of tungstic acid was 1.0% as a solid content relative to the total weight of the solution. Seven samples were formed such that the concentration of tungstic acid was 2.0%, and the # 8 sample was formed such that the concentration of tungstic acid was 5.0%. Spin coating is performed at 1500 rpm for 10 seconds.
The coated film was fired in an electric furnace at 100 ° C. for 30 minutes. As a result of measuring the ratio of tungsten atoms to titanium atoms on the surface by X-ray photoelectron spectroscopy, the sample # 5 was 0%, the sample # 6 was 20%, and the sample # 7 was 40%.
%, # 8 sample was 100%. As a result of evaluating the crystal system of the photocatalytic tungsten oxide on the surface by X-ray diffraction, it was found to be ammonium tungstate. When the surface structure was observed with an atomic force microscope,
6, # 7 sample has almost no difference from # 5 sample of titanium oxide alone, suggesting a structure in which islands or domains consisting of fine particles of ammonium tungstate having a particle size of 10 nm or less are distributed. However, in sample # 8, a structure was observed in which ammonium tungstate completely covered titanium oxide.

The thin film was stored in a dark place until the contact angle with water on the surface of the thin film became stable, and then irradiated with a white fluorescent lamp to measure the change in the contact angle with water on the surface. The white fluorescent lamp uses 10W (Toshiba Lighting & Technology, FL10N),
The ultraviolet illuminance was set to 10 μW / cm ² with an ultraviolet illuminometer (Ushio, UVR-2) on the surface of the thin film. The contact angle with water is measured using a contact angle measuring device (Kyowa Interface Science,
CA-X150) to determine a water drop from a microsyringe.

As a result, as shown in FIG. 10, the film of the photocatalytic titanium oxide alone of # 5 was converted to a contact angle with water of about 5%.
Although it was only hydrophilized up to 10 degrees, the structure where ammonium tungstate was distributed in an island shape on titanium oxide,
The # 7 sample had a higher hydrophilicity sensitivity than the # 6 sample of titanium oxide alone, and was highly hydrophilized to 0 ° in terms of the contact angle with water. However, the sample # 8 in which the titanium oxide was completely covered with ammonium tungstate did not become hydrophilic at all.

Example 3 A titanium oxide coating agent having a solid content of 10% (Nippon Soda, N
DH510C) was formed on a silica-coated glass by dip coating. The manufacturing method is the same as that of the first embodiment.
A liquid in which tungstic acid was dissolved in 25% aqueous ammonia was further coated on the thin film by spin coating (at a rotation speed of 1500 rotations per minute for 10 seconds).
Assuming that the concentration of tungstic acid used at this time is 1.0%,
A plurality of samples were prepared by changing the firing temperature. The # 9 sample was a film of a photocatalytic titanium oxide alone not coated with tungstic acid, the # 10 sample was a firing temperature of 100 ° C. after coating with tungstic acid, the # 11 sample was 300 ° C., and the # 12 sample was # 12.
The sample was formed at 350 ° C., and the # 13 sample was formed at 500 ° C. The crystal system of the photocatalytic tungsten oxide on the surface was evaluated by X-ray diffraction. Tungsten oxide composite phase, # 13
The sample was found to be crystallized photocatalytic tungsten oxide. As a result of measuring the ratio of tungsten atoms to titanium atoms on the surface by X-ray photoelectron spectroscopy, #
Nine samples were 0% and # 10 to # 13 samples were 20%.
When the surface structure was observed with an atomic force microscope, the samples # 10 to # 13 showed almost no difference from the sample # 9 of titanium oxide alone, so the fine particle tungsten compound having a particle size of 10 nm or less was oxidized. This suggests a structure distributed in islands or domains on titanium.

The thin film thus prepared was stored in a dark place until the contact angle with water on the surface became stable, and then irradiated with a white fluorescent lamp to measure the change in the contact angle with water on the surface. The white fluorescent lamp uses 10W (Toshiba Lighting & Technology, FL10N),
The ultraviolet illuminance was set to 3 μW / cm ² with an ultraviolet illuminometer (Ushio, UVR-2) on the surface of the thin film. The contact angle with water can be measured with a contact angle measuring instrument (Kyowa Interface Science, C
AX150) to determine the drop of water from a microsyringe.

FIG. 11 shows the results when the illuminance is 3 μW / cm ² . As a result, in the samples # 10 to # 13 in which the tungsten compound was bonded to the titanium oxide, the hydrophilization rate was faster than in the sample # 9 of titanium oxide alone. The # 10 sample combined with ammonium and the # 11 sample combined with amorphous tungsten oxide when the heat treatment temperature was 300 ° C. had the highest hydrophilization rate. It is considered that grain boundaries were formed in the tungsten oxide particles due to the crystallization of tungsten oxide by heat treatment at 350 ° C or higher.
The 12 and # 13 samples had a faster hydrophilicity than the # 9 sample of titanium oxide alone, but were slower than the # 10 and # 11 samples.

Example 4 A water-based titanium oxide sol (STS21, Ishihara Sangyo) was diluted with pure water until the solid content concentration became 8%, formed into a film on a silica-coated glass by a spin coating method, and then subjected to a 500 muffle furnace.
Firing was performed for 30 minutes. Spin coating at 1500 per minute
The rotation was performed for 10 seconds. A liquid in which tungstic acid was dissolved in 25% aqueous ammonia was further coated on the thin film by spin coating (at a rotation speed of 1500 rotations per minute for 10 seconds). At this time, the concentration of the tungstic acid used was set to 1.0%, and the firing temperature was changed to prepare a plurality of samples. The # 14 sample was a film of a photocatalytic titanium oxide alone not coated with tungstic acid, and the # 15 sample had a firing temperature of 100 after coating with tungstic acid.
Sample # 16 was formed to a temperature of 300 ° C. As a result of evaluating the crystal system of the photocatalytic tungsten oxide on the surface by X-ray diffraction, the # 15 sample was ammonium tungstate,
16 samples were found to be amorphous tungsten oxide. As a result of measuring the ratio of tungsten atoms to titanium atoms on the surface by X-ray photoelectron spectroscopy,
The # 14 sample was 0%, and the # 15 and # 16 samples were 20%. When the surface structure was observed with an atomic force microscope, it was found that the # 15 and # 16 samples had almost no difference from the # 14 sample of titanium oxide alone.
It was suggested that the following fine particles of the tungsten compound were distributed in the form of islands or domains on titanium oxide.

The thin film thus prepared was stored in a dark place until the contact angle with water on the surface became stable, and then irradiated with a white fluorescent lamp, and the change in the contact angle with water on the surface was measured. The white fluorescent lamp uses 10W (Toshiba Lighting & Technology, FL10N),
The ultraviolet illuminance was set to 1 μW / cm ² with an ultraviolet illuminometer (Ushio, UVR-2) on the surface of the thin film. The contact angle with water can be measured with a contact angle measuring instrument (Kyowa Interface Science, C
AX150) to determine the drop of water from a microsyringe.

As a result, as shown in FIG. 12, the film of the photocatalytic titanium oxide alone of # 14 had a water contact angle of 10%.
Although the sample was not hydrophilized below the temperature, the tungsten compounds were distributed in the form of islands on the titanium oxide. The samples # 15 and # 16 were converted to water contact angles by irradiating weak light with an ultraviolet illuminance of 1 μW / cm ^2. Highly hydrophilic up to 1 degree.

Example 5 A photocatalytic anti-fogging film containing photocatalytic titanium oxide and silica (Totoku Kikai Co., Ltd., Hydrotectomirror film) was stuck on glass, and tungstic acid was added with 25% aqueous ammonia. Was coated by a spin coating method (rotation speed of 1500 rpm for 10 seconds) and dried at 100 ° C. for 30 minutes. The concentration of tungstic acid used at this time was 1.0%. As a result of evaluating the crystal system of the photocatalytic tungsten oxide on the surface by X-ray diffraction, it was found to be ammonium tungstate. The proportion of tungsten atoms on the surface measured by X-ray photoelectron spectroscopy was 20%. When the surface structure was observed with an atomic force microscope, the structure was similar to that of the film not coated with ammonium tungstate. Therefore, fine particles of ammonium tungstate having a particle size of 10 nm or less were not formed on the titanium oxide and silica in an island form. This suggests a domain-like structure.

The prepared thin film was stored in a dark place until the contact angle with water on the surface became stable, and then irradiated with a white fluorescent lamp to measure the change in the contact angle with water on the surface. The white fluorescent lamp uses 10W (Toshiba Lighting & Technology, FL10N),
The ultraviolet illuminance was set to 10 μW / cm ² with an ultraviolet illuminometer (Ushio, UVR-2) on the surface of the thin film. The contact angle with water is measured using a contact angle measuring device (Kyowa Interface Science,
CA-X150) to determine a water drop from a microsyringe.

As a result, as shown in FIG. 13, when an island portion or a domain portion made of a photocatalytic tungstate is further joined to an antifogging film in which a photocatalytic titanium oxide and silica are combined, UV illumination 10μW / cm
^By the light irradiation of ² , the surface was highly hydrophilized to a water contact angle of 5 degrees or less.

Example 6 A titanium oxide coating agent having a solid content of 10% (Nippon Soda, N
DH510C) was formed on a silica-coated glass by dip coating. Dip coating was performed at a pulling rate of 15 cm / min, and the coated film was baked in an electric furnace at 500 ° C. for 30 minutes. This process was repeated twice to produce a photocatalytic titanium oxide thin film having a thickness of about 200 nm. A liquid in which tungstic acid was dissolved in 25% aqueous ammonia was coated on the thin film by spin coating. The concentration of tungstic acid used at this time was set to 1.0%, and spin coating was performed at 1500 per minute.
The rotation was performed for 10 seconds at a rotation speed, and the coated film was fired in an electric furnace at 300 ° C. for 30 minutes. On top of this, colloidal silica (Nissan Chemical, ST-O
A liquid obtained by diluting S) with pure water so as to have a solid concentration of 0.05% was formed into a film by a spin coating method, and then dried and solidified.
Spin coating is performed at a rotation speed of 1500 rpm for 10 seconds, and the coated film is heated at 150 ° C. in an electric furnace.
Drying was performed for 30 minutes. The ratio of tungsten atoms and silicon atoms to titanium atoms on the surface was measured by X-ray photoelectron spectroscopy.
% And silicon atoms were 40%. As a result of evaluating the crystal system of tungsten oxide by X-ray diffraction, it was found that the tungsten oxide was amorphous photocatalytic tungsten oxide.

The change in contact angle with water on the surface when the prepared thin film was stored in a clean dark place was measured. The contact angle with water was determined by dropping a water drop from a micro syringe using a contact angle measuring device (Kyowa Interface Science, CA-X150).

FIG. 14 shows the change in the contact angle with water in a clean dark place. A sample formed by further forming silica on the surface of a member in which an amorphous tungsten oxide island-like or domain-like portion is bonded on photocatalytic titanium oxide is used for a long period of 1000 hours. The contact angle was maintained at 5 degrees or less.

Example 7 Titanium oxide coating agent having a solid content of 10% (Nippon Soda, N
DH510C) was formed on a silica-coated glass by dip coating. Dip coating was performed at a pulling rate of 15 cm / min, and the coated film was baked in an electric furnace at 500 ° C. for 30 minutes. This process was repeated twice to produce a photocatalytic titanium oxide thin film having a thickness of about 200 nm. A solution obtained by diluting tin oxide sol (Taki Kagaku, S-8) with pure water was further coated on the thin film by spin coating. At this time, by changing the concentration of the tin oxide sol, a plurality of thin films having different loading amounts of the photocatalytic tin oxide on the titanium oxide were obtained. # 17
The sample is a film of a photocatalytic titanium oxide alone not coated with a tin oxide sol, the # 18 sample has a tin oxide concentration of 0.1% by solid content ratio based on the total weight of the solution, and the # 19 sample has a tungstic acid concentration of 0.2%. The film was formed as follows. The spin coating was performed at a rotation speed of 1500 revolutions per minute for 10 seconds, and the coated film was baked at 500 ° C. for 30 minutes in an electric furnace. As a result of evaluating the crystal system of tin oxide on the surface by X-ray diffraction, a rutile-type crystal structure was obtained. Further, it is considered that the photocatalytic tin oxide in the thin film exists as an island or a domain on the titanium oxide thin film.

The thin film thus prepared was stored in a dark place until the contact angle with water on the surface became stable, and then irradiated with a white fluorescent lamp to measure the change in the contact angle with water on the surface. The white fluorescent lamp uses 10W (Toshiba Lighting & Technology, FL10N),
The ultraviolet illuminance was set to 10 μW / cm ² with an ultraviolet illuminometer (Ushio, UVR-2) on the surface of the thin film. The contact angle with water is measured using a contact angle measuring device (Kyowa Interface Science,
CA-X150) to determine a water drop from a microsyringe.

FIG. 15 shows the change in the contact angle with water when the UV illuminance is 10 μW / cm ² . The # 17 sample of the photocatalytic titanium oxide alone was hydrophilized only up to 12 degrees in terms of the contact angle with water, but an island or domain composed of photocatalytic tin oxide was placed on the photocatalytic material titanium oxide thin film. In the # 18 and # 19 samples in which the portions were joined, the hydrophilicity-improving sensitivity was improved as compared with the # 17 sample of titanium oxide alone.

[0062]

According to the present invention, it is possible to provide a member capable of causing a surface-hydrophilizing reaction at a practical level in response to weak light at an indoor lighting level even with a small amount of titanium oxide.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a charge transfer process when both titanium oxide and a second photocatalyst of the present invention are photoexcited.

FIG. 2 is a view for explaining a charge transfer process when a second photocatalyst of the present invention is photoexcited.

FIG. 3 is a diagram illustrating a charge transfer process when the photocatalytic titanium oxide of the present invention is photoexcited.

FIG. 4 is a diagram showing one embodiment of the present invention.

FIG. 5 is a diagram showing another embodiment of the present invention.

FIG. 6 is a diagram showing another embodiment of the present invention.

FIG. 7 is a diagram showing another embodiment of the present invention.

FIG. 8 shows an ultraviolet illuminance of 10 according to the first embodiment of the present invention.
diagram showing the relationship between contact angle and the light irradiation time with water of the specimen surface in the case of μW / cm ^2.

FIG. 9 shows that the ultraviolet illuminance is 3 μm according to the first embodiment of the present invention.
FIG. 9 is a graph showing the relationship between the contact angle of the sample surface with water and the light irradiation time at W / cm ² .

FIG. 10 is a diagram showing a relationship between a contact angle of a sample surface with water and a light irradiation time according to a second embodiment of the present invention.

FIG. 11 is a diagram showing a relationship between a contact angle of a sample surface with water and a light irradiation time according to a third embodiment of the present invention.

FIG. 12 is a diagram illustrating a relationship between a contact angle of a sample surface with water and a light irradiation time according to a fourth embodiment of the present invention.

FIG. 13 is a diagram showing a relationship between a contact angle of a sample surface with water and a light irradiation time according to a fifth embodiment of the present invention.

FIG. 14 is a diagram showing a relationship between a contact angle of a sample surface with water and a storage time in a dark place according to Example 6 of the present invention.

FIG. 15 is a diagram illustrating a relationship between a contact angle of a sample surface with water and a light irradiation time according to a seventh embodiment of the present invention.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // C03C 17/34 C03C 17/34 Z (72) Inventor Toshiya Watanabe 6-15 Kugenuma Coast, Fujisawa City, Kanagawa Prefecture No. 7 F-term (reference) 4F100 AA17B AA17C AA21B AA28C AA33C AG00 AH03 AT00A BA03 BA07 BA10A BA10C DE01B EH46 EJ42 EJ48 GB07 GB08 GB32 GB76 JA12C JB05 JG10C JL06 JL08B JL08CJ0A01A01A BA48A BB04A BB04B BB20A BB20C BC22A BC22B BC60A BC60B BC60C BE17B CD10 DA05 EA08 EB15X EB15Y EB18X EB18Y EC22Y EC26 EC27 EC30 ED02 ED04 EE01 EE06 FA01 FA03 FB02 FB23 FC02 FC07

Claims (17)

[Claims] 1. A substrate comprising a substrate and a film formed on the surface of the substrate, wherein the film comprises a layer containing photocatalytic titanium oxide particles formed on the surface of the substrate, and a layer other than titanium oxide on the layer. Consisting of island-shaped or domain-shaped portions made of the second photocatalytic material, wherein at least a portion of the photocatalytic titanium oxide particles and at least a portion of the second photocatalyst are joined, and the photocatalytic At least a part of the layer containing titanium oxide is present in a state where it can come into contact with moisture in the outside air, and the potential at the lower end of the conduction band of the second photocatalytic material is pH = 7. It is more positive than 0 V in terms of potential, and the potential at the upper end of the valence band of the second photocatalytic material is more positive than +2.7 V in terms of the standard hydrogen electrode potential when pH = 7. And
A hydrophilic member, wherein light having a wavelength capable of photoexciting the photocatalytic material can reach at least one of the photocatalytic titanium oxide and the second photocatalytic material. 2. The hydrophilic member according to claim 1, wherein light having a wavelength capable of photoexciting both the photocatalytic titanium oxide and the second photocatalytic material can reach. 3. The hydrophilic member according to claim 1, wherein the particle size of the second photocatalytic material is 50 nm or less. 4. The hydrophilic member according to claim 1, wherein the particle size of the second photocatalytic material is 10 nm or less. 5. The method according to claim 1, wherein a coverage of the second photocatalytic material on the substrate surface is in a range of 0.5% to 50% in terms of a value measured by X-ray photoelectron spectroscopy. Item 5. The hydrophilic member according to any one of Items 1 to 4. 6. The hydrophilic member according to claim 1, wherein the second photocatalytic material is tin oxide. 7. The hydrophilic member according to claim 1, wherein the second photocatalytic material is amorphous tungsten oxide or tungstate. 8. A film containing the titanium oxide and the second photocatalyst further contains a metal oxide capable of adsorbing more chemically adsorbed water than titanium oxide, and a part of the metal oxide is exposed to the outside air. The hydrophilic member according to any one of claims 1 to 7, wherein: 9. A metal oxide layer capable of adsorbing more chemically adsorbed water than titanium oxide is formed on the surface of the coating, and the thickness of the metal oxide is in the range of 1 nm to 100 nm. The hydrophilic member according to claim 1, wherein 10. The metal oxide capable of adsorbing more chemically adsorbed water than titanium oxide has at least one bond selected from the group consisting of a siloxane bond, a borosiloxane bond, and an aluminosilicate bond. The hydrophilic member according to claim 8. 11. The hydrophilic member according to claim 1, wherein the surface layer is substantially transparent. 12. The hydrophilic member according to claim 1, wherein the substrate is a building exterior material. 13. The hydrophilic member according to claim 1, wherein the base material is a building interior material. 14. The method of claim 1, wherein the photoexcitation of the photocatalytic material is a fluorescent light,
14. The hydrophilic member according to claim 13, wherein the light is emitted from an indoor lighting device such as an incandescent lamp. 15. A method for producing a hydrophilic member according to claim 1, wherein a step of forming a layer containing photocatalytic crystalline titanium oxide on the surface of the substrate, and then a second photocatalyst thereon. A method for producing a hydrophilic member, comprising a step of applying a solution containing a starting material of a hydrophilic material, and a step of solidifying. 16. The starting material of the second photocatalytic material is an aqueous solution of ammonium tungstate, and the heat treatment for solidifying the ammonium tungstate is performed at a temperature of 20 ° C.
The method for producing a hydrophilic member according to claim 15, wherein the temperature is in a range of 500 ° C. 17. The starting material of the second photocatalytic material is an aqueous solution of ammonium tungstate, and the heat treatment for solidifying the ammonium tungstate is performed at 20 ° C.
The method for producing a hydrophilic member according to claim 15, wherein the temperature is in a range of 350 ° C.