JP3385850B2 - Composite material with hydrophilicity - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a technique for making a surface of a base material highly hydrophilic and maintaining it.

[0002]

2. Description of the Related Art In the fields of construction and coating, stains on building exterior materials, outdoor structures and their coating films have become a problem due to environmental pollution. Soot and particles floating in the atmosphere accumulate on the roof and outer walls of buildings in fine weather. The sediment is washed away by rainwater as it rains and flows down the outer wall of the building. Furthermore, in rainy weather, suspended dust is carried by rain and flows down on the outer wall of a building or the surface of an outdoor structure. As a result, contaminants adhere to the surface along the rainwater path. When the surface dries, striped stains appear on the surface. Dirt on building exterior materials and coatings consists of combustion products such as carbon black, urban soot and contaminants of inorganic materials such as clay particles. It is thought that such a variety of pollutants complicates antifouling measures (Yoshinori Tachibana, "Method for accelerating contamination of exterior wall finishing materials", Architectural Institute of Japan, Proceedings of Structural Papers, No. 404, October 1989, p.15-2
4).

The conventional wisdom is that polytetrafluoroethylene (PTF) is used to prevent stains on building exteriors.
It was thought that a water-repellent coating such as E) was preferable, but recently, it has been thought that it is desirable to make the surface of the coating film as hydrophilic as possible with respect to urban dust containing a large amount of lipophilic components. (Polymer, Vol. 44, May 1995, p. 307). Therefore, it has been proposed to coat a building with a hydrophilic graft polymer (newspaper "Chemical Industry Daily", January 30, 1995). Reportedly, this coating film exhibits hydrophilicity with a contact angle with water of 30 to 40 °.

However, the contact angle of the inorganic dust typified by clay minerals with water is 20 to 50 °, which has an affinity for the graft-polymerized polymer having a contact angle with water of 30 to 40 °. It is considered that the coating film of this graft-polymerized polymer cannot prevent stains due to inorganic dusts because it easily adheres to the surface.

On the other hand, hydrophilic resins include materials having hydrophilicity superior to that of the above graft-polymerized polymers represented by polyamides, but these materials exhibit swelling property and cannot form a hard coating film. .

Therefore, the present inventor has proposed a thin film containing an optical semiconductor having a hydrophilic surface as a coating film for building exterior materials and outdoor buildings. When this thin film is used as a building exterior material or a coating film for outdoor construction, when light with a wavelength of energy higher than the band gap energy of optical semiconductors is sufficiently irradiated with sufficient illuminance, the electrons in the valence band become Excited to the conduction band to generate holes and conduction electrons, which is probably due to some reason water on the surface of the coating film contains hydroxyl groups (OH
^- ) Form the chemical adsorption phenomenon and the physical adsorption phenomenon by hydrogen bonding on it, and it is highly hydrophilic to the state where the contact angle of water on the surface of the coating film is 10 ° or less. It will be transformed. Further, it has been found that a thin film containing an optical semiconductor can form a hard coating film, unlike polyamide or the like.

[0007]

However, in the field of pigments, when an optical semiconductor is contained in a general coating material as it is, it is a cause of deterioration or discoloration of a resin component in the coating material by photooxidation. It has been thought to be. Therefore, for example, when anatase-type titanium oxide particles, which is one type of optical semiconductor, is used as a white pigment, the titanium oxide particles are coated with alumina or silica, and conduction electrons and holes generated by photoexcitation of the optical semiconductor diffuse to the particle surface. It was preventing it. Therefore, when a thin film containing an optical semiconductor is applied to a surface coated with these general paints, it may similarly cause photo-oxidation deterioration.

Further, for optical semiconductors, a proposal has been made for a method of precipitating and removing dissolved metal ions in water by utilizing its photoreduction effect (Japanese Patent Laid-Open No. 61-18).
494). Conversely, this proposal, conversely, when a member formed with a coating film composed of a thin film containing an optical semiconductor is used in an aqueous environment in which ions of a colored metal such as iron are dissolved, the colored metal precipitates and the appearance Suggests that it may damage the.

In view of the above circumstances, the present invention does not cause photo-oxidative deterioration even when applied to a coated surface of a general paint, and
It is an object of the present invention to provide a composite material including a thin film containing an optical semiconductor that does not impair the appearance by precipitation of a colored metal even when used in an aqueous environment.

[0010]

The present invention is based on the discovery that the phenomenon of hydrophilization of a composite material surface by an optical semiconductor is basically different from the photo-oxidation-reduction reaction by an optical semiconductor. . Based on this finding, the present inventor has finally found that there is a structure exhibiting a hydrophilization phenomenon, although the photo-semiconductor thin film shows almost no photo-oxidation-reduction reaction in design.

In the present invention, when the energy level of the conduction band of the optical semiconductor is set to 0 eV for the hydrogen generation level,
It should be located at a positive value. The conventional theory regarding the photooxidation / reduction reaction is that a conduction electron-hole pair is generated by photoexcitation, and then the reduction reaction by the conduction electron and the oxidation reaction by the hole are simultaneously promoted and proceed. Therefore, tin oxide and rutile, whose lower end of the energy level of the conduction band of the optical semiconductor is not sufficiently high on the negative side, have a structure in which the reduction reaction by conduction electrons is difficult to proceed and only the oxidation reaction by holes is easily promoted. In such a structure, the conduction electrons become excessive, and the electron-hole pairs generated by photoexcitation recombine without participating in the redox reaction, so that an oxidation reaction and a reduction reaction hardly occur in practice. However, as described later, the hydrophilization phenomenon by photoexcitation progresses.

When the photo-oxidation / reduction reaction of an optical semiconductor is used for decomposing an organic substance, the decomposition reaction is carried out by utilizing water and oxygen in the environment. That is, the conduction electrons generated by photoexcitation reduce oxygen to generate superoxide ions (O
₂ ^-) to generate the hole is to oxidize the hydroxyl group to generate a hydroxyl radical (· OH), these highly reactive oxygen species (O ₂ ^- organics by oxidation-reduction reaction of and · OH) Is decomposed. Therefore, in order to effectively photooxidatively decompose an organic substance, the energy level at the upper end of the valence band for generating holes is the oxygen generation level (+ 0.82e) at which the hydroxyl group emits electrons.
V) is located on the positive side, and the energy level at the bottom of the conduction band generated by conduction electrons is located on the negative side from the hydrogen generation level (0 eV) at which hydrogen emits electrons to donate to the oxygen side. It will be good. Therefore, conversely, in order to prevent the photooxidation / reduction decomposition of organic matter effectively, the energy level at the upper end of the valence band should be set to the negative side of the oxygen production level (+0.82 eV), or the energy at the lower end of the conduction band should be set. It suffices to position the level on the positive side of the hydrogen generation level (0 eV).

When the photo-oxidation / reduction reaction of an optical semiconductor is used for the deposition of metal ions in water, the conduction ions generated by photoexcitation cause the reduction and deposition of metal ions. (At the same time, the holes oxidize the hydroxyl groups in the water to cause hydroxyl radicals (.O
H). Therefore, for example, in order to effectively remove iron ions from water by deposition, the energy level at the lower end of the conduction band generated by conduction electrons needs to be located on the negative side of the iron generation level (-0.44 eV). . Therefore, conversely, in order to prevent metal ions from precipitating from water, the energy level at the lower end of the conduction band should be located on the positive side of the metal production level. If the noble metal is excluded, the production level of the metal is on the negative side of the hydrogen production level. Therefore, the energy level at the bottom of the conduction band is eventually set to the hydrogen production level (0e
V) should be located on the positive side.

From the above, as one method of photohydrophilization while suppressing the decomposition of resin and the precipitation of metal ions dissolved in water, the energy level of the conduction band of the optical semiconductor is set to 0 eV for the hydrogen generation level. It turns out that there is a way to position it in a positive value.

In the present invention, a layer containing a photo-semiconductor and a hydrophilic substance other than the photo-semiconductor is formed on the surface of the base material, and the photo-semiconductor is brought into a state where it is not in contact with the outside air. In such a state, most of the conduction electrons and holes generated by photoexcitation of the photo-semiconductor do not diffuse to the surface, and the probability of contact with surface reactive species such as water, oxygen and metal ions is drastically reduced. The reduction reaction is suppressed. The amount of conduction electrons and holes generated in a coating film having a thin film thickness and / or a low photo-semiconductor particle content is sufficient to exhibit sufficient abrasion resistance with an excitation light illuminance of 1 mW / cm ² or less. Originally, it can be suppressed to such an extent that the photo-redox reaction hardly occurs. Nevertheless, the photohydrophilization reaction proceeds as described later.

In the present invention, a layer containing an optical semiconductor and a substance that inhibits the photoredox reaction of the optical semiconductor is formed on the surface of the base material. Although the mechanism is not clear, alkali metal, alkaline earth metal, alumina, zirconia, silica, antimony oxide, and amorphous titanium oxide weaken the photooxidation / reduction performance of optical semiconductors (“titanium oxide”, Gihodo (1991)). The amount of conduction electrons and holes generated in a coating film having a thin film thickness and / or a low photo-semiconductor particle content is sufficient to exhibit sufficient abrasion resistance with an excitation light illuminance of 1 mW / cm ² or less. Originally, it can be suppressed to such an extent that the photo-redox reaction hardly occurs. But,
Even if these substances are contained in the layer, the photohydrophilization reaction proceeds as described later.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, when a base material requiring hydrophilicity on the surface is prepared, and the lower end of the energy level of the conduction band is set to 0 eV for the hydrogen generation level, A thin film containing optical semiconductor particles located at a positive value is formed. The second configuration of the present invention is to prepare a substrate that requires hydrophilicity of the surface,
A thin film containing optical semiconductor particles and a hydrophilic substance that is not an optical semiconductor is formed thereon. At that time, the optical semiconductor should be in a state where it is not in contact with the outside air. According to the third configuration of the present invention, a base material whose surface needs to be hydrophilized is prepared, and a thin film containing photo-semiconductor particles and a substance that inhibits the photo-redox reaction of the photo-semiconductor is formed thereon.

The term "hydrophilization" as used herein means a phenomenon in which the wettability of the surface is increased by an external factor and the contact angle with water is reduced. The photohydrophilization is a case where the external factor is light in the above. The term “highly hydrophilic” or “superhydrophilic” means that the contact angle with water is 10 ° or less, preferably 5 ° or less.

Optical semiconductors that can be preferably used in the present invention include anatase type titanium oxide, rutile type titanium oxide, zinc oxide, tin oxide, strontium titanate, tungsten trioxide, dibismuth trioxide, ferric oxide and the like. The metal oxides of

Photoconductors whose lower end of the energy level of the conduction band which can be preferably used in the present invention has a positive value when the hydrogen generation level is 0 eV are tin oxide, tungsten trioxide and trioxide. Examples thereof include metal oxides such as dibismuth, ferric oxide and rutile type titanium oxide.

The hydrophilic substance which is not a photo-semiconductor which can be suitably used in the present invention is silica, amorphous titanium oxide, an inorganic oxide such as alumina, silanol, polysilanol, or at least a part of an organo group bonded to a silicon atom. Examples thereof include silicone resins substituted with hydroxyl groups.

Known substances that inhibit the photo-oxidation / reduction reaction of optical semiconductors are alkali metals, alkaline earth metals, alumina, zirconia, silica, antimony oxide, amorphous titanium oxide, aluminum and manganese.

The substrate to which the present invention is applicable is not particularly limited. Suitable for general resin film, coated board, decorative board, plastic, wood, artificial marble, etc. for the purpose of forming a coating film that does not cause photooxidation deterioration even when applied to the painted surface of general paint It is possible. For the purpose of forming a coating film that does not impair the appearance of colored metal deposited even when used in an aqueous environment, ceramic products, general resin films, coated boards, decorative boards, plastics, wood,
It can be suitably used for artificial marble, stone, glass, metal, concrete, combinations thereof, laminates thereof, and the like.

In the present invention, it is preferable that the film thickness is thin. Preferably 1 μm or less, more preferably 0.2 μm
The following is good. Then, the absolute amount of the optical semiconductor fixed on the base material can be reduced, and the photo-oxidation / reduction property can be further reduced. Also, the wear resistance is improved. Further, particularly when the thickness is 0.2 μm or less, the transparency of the thin film containing the optical semiconductor can be easily ensured, and the design and transparency of the base can be maintained.

In the present invention , the optical semiconductor content is preferably 5 to 80% by weight, more preferably 10 to 50% by weight, based on the optical semiconductor containing layer. This is because the photooxidation / reduction property can be lowered as the content of the optical semiconductor is reduced. However, since the photohydrophilization phenomenon is also a phenomenon based on the photoexcitation phenomenon of the optical semiconductor, it is necessary to contain about 5% or more.

In the present invention, the illuminance of light having a wavelength equal to or shorter than the excitation wavelength is preferably 0.0001 to 1 mW / cm ² ,
More preferably, it is about 0.001 to 1 mW / cm ² . This is because the lower the illuminance of light having a wavelength equal to or shorter than the excitation wavelength, the smaller the amount of generated electron-hole pairs, and the lower the photooxidation / reduction property. However, since the photohydrophilization phenomenon is also a phenomenon based on the photoexcitation phenomenon of an optical semiconductor, it is about 0.0001 mW.
Excitation light illuminance of at least / cm ² is required.

In the present invention, the light source for exciting the optical semiconductor may be any light source capable of emitting an illuminance of light having a wavelength of the excitation wavelength or less, such as sunlight, fluorescent lamps, incandescent lamps, metal halide lamps, and mercury lamps. Interior lighting such as can be used.

In the present invention, an intermediate layer may be provided between the base material and the photosemiconductor-containing layer. This increases the adhesion to the base material and improves the wear resistance.

In the present invention, the photo-semiconductor particles in which the lower end of the energy level of the conduction band is located at a positive value when the hydrogen production level is 0 eV on the substrate whose surface needs to be hydrophilized For example, the following methods are available for forming a thin film containing (1) The above-mentioned optical semiconductor particles are applied to the surface of the base material and baked. (2) On the surface of the base material, an organic compound (alkoxide, chelate, acetate, etc.) containing the constituent element metal species of the above-mentioned photo-semiconductor metal oxide or an inorganic compound (chloride,
(Sulfate, etc.) is hydrolyzed, applied to a substrate, and dehydrated by a method such as heating. If the metal oxide is not crystallized up to this process like titanium oxide, it is further heated to crystallize the metal oxide. (3) After the constituent element metal of the semiconductor metal oxide is fixed on the surface of the base material by sputtering or the like, it is oxidized by a method such as heating or an electrode reaction. If the metal oxide is not crystallized up to this process like titanium oxide, it is further heated to crystallize the metal oxide.

In the present invention, the method for forming a thin film containing optical semiconductor particles and a hydrophilic substance that is not an optical semiconductor on a substrate that requires hydrophilicity depends on the kind of hydrophilic substance that is not an optical semiconductor. different. (I) When the hydrophilic substance that is not an optical semiconductor is an inorganic oxide such as silica or alumina (1) Optical semiconductor particles and the above inorganic oxide particles are applied to the surface of a base material and baked. (2) On the surface of the base material, hydrated photo-semiconductor particles and an organic compound (alkoxide, chelate, acetate, etc.) containing a constituent element metal species of the above-mentioned inorganic oxide or an inorganic compound (chloride, sulfate, etc.) which is not an oxide. The decomposition product is applied to a base material and dehydrated by a method such as heating. (3) On the surface of the base material, the inorganic oxide particles and an organic compound (alkoxide, chelate, acetate, etc.) containing the constituent element metal species of the optical semiconductor particles or an inorganic compound (chloride, sulfate, etc.) which is not an oxide The hydrolyzate is applied to a base material and dehydrated by a method such as heating. If the metal oxide is not crystallized up to this process like titanium oxide, it is further heated to crystallize the metal oxide. (II) In the case of a silicone resin in which a hydrophilic substance which is not a photo-semiconductor is substituted with at least a part of an organo group bonded to a silicon atom, a photo-semiconductor particle and a silicone resin and / or a precursor thereof (organoalkoxysilane, and its Hydrolyzate) is applied to the substrate and heated. As a result, it is hydrolyzed as required, and then dehydration polycondensation is performed and cured to fix the optical semiconductor particles and the silicone resin on the substrate. Then, the photo-semiconductor is irradiated with light having a wavelength not longer than the excitation wavelength to substitute at least a part of the organo group bonded to the silicon atom in the silicone resin with a hydroxyl group.

In the present invention, a method for forming a thin film containing photo-semiconductor particles and a substance that inhibits the photo-oxidation-reduction reaction of the photo-semiconductor on a base material whose surface needs to be hydrophilized includes, for example, the following methods. is there. (1) The surface of the base material is coated with a compound containing the photo-semiconductor particles and the constituent element metal species in the inhibiting substance, and then baked. (2) A compound containing a constituent element metal species in the inhibiting substance and an organic compound containing a constituent element metal species of the optical semiconductor particles (alkoxide, chelate, acetate, etc.) on the substrate surface
Or inorganic compounds that are not oxides (chlorides, sulfates, etc.)
The hydrolyzate of is applied to a base material, and dehydration reaction is performed by a method such as heating. If the metal oxide is not crystallized up to this process like titanium oxide, it is further heated to crystallize the metal oxide.

Reference Example 1. (Titanium oxide + silicone, change in film thickness) First, a 10 cm square aluminum substrate was previously coated with a silicone layer in order to smooth the substrate surface. For this reason,
Liquid A (silica sol) and liquid B (trimethoxymethylsilane) of the Japanese synthetic rubber coating composition "GLASCA" were mixed in a weight ratio of 3, and the mixed liquid was applied to an aluminum substrate, Curing was performed at a temperature of ° C to obtain a plurality of aluminum substrates (# 1 sample) coated with a silicone base coat having a thickness of 3 µm. Next, a thin film made of an optical semiconductor and a silicone resin was formed on the surface of the # 1 sample. More specifically, anatase titania sol (manufactured by Nissan Kagaku, T
A-15) and the solution A of "GLASCA" were mixed and diluted with ethanol, and then the solution B of "GLASCA" was added to prepare a titanium oxide-containing silicone coating composition. Here, the liquids A and B of "grasca" were adjusted to have a weight ratio of 3. Apply this coating composition to the surface of # 1 sample and
It is cured at a temperature of 50 ° C. to form a top coat composed of anatase type titania particles and a silicone resin.
# 6 sample was obtained. # 2 sample has a topcoat thickness of 0.0
3 μm, # 3 sample top coat film thickness is 0.1 μm, #
The topcoat film thickness of the 4 samples was 0.2 μm, the topcoat film thickness of the # 5 sample was 0.6 μm, and the topcoat film thickness of the # 6 sample was 2.5 μm. In all samples, the total weight of silica and silicone resin was 1 with respect to 1 weight of anatase-type titania particles. Each sample was irradiated with ultraviolet rays using a 20 W BLB fluorescent lamp (manufactured by Sankyo Denki Co., Ltd.) at an ultraviolet illuminance of 0.5 mW / cm ² , and a contact angle measuring device (manufactured by ERMA, model GI-100).
0) was used to examine the temporal change of the contact angle of the surface of the sample with water. The contact angle was measured 30 seconds after dropping a water droplet from the microsyringe on the sample surface. The results are shown in the graph of FIG. As can be seen from the graph of FIG. 1, the surface of each sample was highly hydrophilized within 50 hours of irradiation regardless of the film thickness, and the contact angle with water was less than 3 °. Next, in order to examine the photo-oxidation / reduction performance of the # 2 to # 6 samples, the photodegradation performance of methyl mercaptan was examined. Each sample was placed in a desiccator made of quartz glass and capable of transmitting ultraviolet rays and having a volume of 11 liters, and nitrogen gas containing methyl mercaptan was injected so that the concentration of methyl mercaptan was 3 ppm. 8 cm from the sample
A 4 W BLB fluorescent lamp (manufactured by Sankyo Denki Co., Ltd.) was placed at a distance of 3 mm, and ultraviolet rays were irradiated at an ultraviolet illuminance of 0.3 mW / cm ² . After 30 minutes, the gas in the desiccator was sampled, the methyl mercaptan concentration was measured by gas chromatography, and the methyl mercaptan removal rate was determined. The result is shown in Figure 2.
Is shown in the graph. As can be seen from the graph of FIG. 2, in this case, the photodecomposition performance of methyl mercaptan, that is, the photoredox performance has a film thickness dependence, and the photodecomposition performance is considerably suppressed when the film thickness is 1 μm or less. In order to further verify this tendency, as a comparative sample, after forming a silica layer on an aluminum substrate (coating the substrate after hydrolysis of tetraethoxysilane and curing by dehydration polycondensation at 150 ° C.), simply anatase-type titania sol ( Nissan Chemical Industries, Ltd. TA-15) was applied and baked at 400 ° C. to prepare a sample (film thickness 0.4 μm), and the removal rate of methyl mercaptan was measured.
%, Which is very high, and the effect of suppressing the photo-oxidation / reduction performance by adding a silicone resin at a film thickness of 1 μm or less was confirmed.

Reference Example 2. (Titanium oxide + silicone, surface AES analysis) For the sample # 3 of Reference Example 1 (top coat film thickness 0.1 μm), elemental analysis in the cross-sectional direction was performed by Auger spectroscopy. The results are shown in FIGS. 3 (a) to 3 (c). Figure 3
(A) shows the elemental analysis result of the outermost surface of the sample. Figure 3
As can be seen from (a), Si, C,
N and O were observed, but Ti was not observed. Ti
Was not observed, there is almost no titanium oxide, which is an optical semiconductor, on the outermost surface of the sample, in other words,
It is considered that they are not in contact with the outside air. On the other hand, Si, C, and O were observed because silicone was present on the outermost surface. Furthermore, it is considered that N was observed because nitrogen derived from nitric acid was observed because the dispersion liquid of titanium oxide sol was nitric acid. Figure 3 (b)
Shows the elemental analysis result of 0.02 μm lower layer surface from the outermost surface of the sample. As can be seen from FIG. 3B, Ti, in addition to Si, C, N and O, was observed in this cross section. From the observation of Ti, it can be seen that titanium oxide, which is an optical semiconductor, exists 0.02 μm below the outermost surface of the sample. Silicon was also present in this cross section because Si, C and O were observed at the same time. FIG. 3C shows the elemental analysis result of the lower layer surface of 0.2 μm from the outermost surface of the sample, that is, the inner cross section of the base coat. As can be seen from FIG. 3 (b), Si, C, and O are recognized in this cross section, and it can be seen that the cross section is made of only silicone. From the above, Example 1
In the production method, a photo-semiconductor (anatase-type titanium oxide) and a non-photo-semiconductor hydrophilic substance (silicone resin itself is a hydrophobic substance on the surface of the substrate, but the organo-organism that binds to the silicon atom in the silicone by photoexcitation of the photo-semiconductor by UV irradiation. A composite material including a layer containing a group (a methyl group in Example 1 is converted into a hydrophilic substance when at least a part of the group is replaced with a hydroxyl group), and a photosemiconductor is hardly exposed to the outside air. It was confirmed that the above can be produced.

Reference Example 3. (Titanium oxide + silicone, Raman spectroscopic analysis of surface after hydrophilization) 22.8 mW / c using # 3 sample of Reference Example 1 with a mercury lamp
The sample was irradiated with ultraviolet rays for 2 hours at an ultraviolet illuminance of m ² to obtain a # 7 sample. Raman spectroscopic analysis was performed on the # 3 sample before irradiation and the # 7 sample after irradiation. For comparison, the # 1 sample of Example 1 was also irradiated with ultraviolet rays under the same conditions, and Raman spectroscopic analysis of the sample before and after irradiation was performed. The Raman spectrum is shown in the graph of FIG. Since the Raman spectra of the # 1 sample before and after irradiation were the same, the curve # 1 is shown in the graph of FIG. Figure 4
Referring to the graph, in the Raman spectrum of the # 3 specimen, the position of the wave number 2910cm ^-1 is observed a large peak of C-H bonds symmetric stretching of sp ³ hybrid orbital, the position of the wave number 2970cm ^-1 is sp A large peak of C-H bond antisymmetric expansion and contraction of ^three hybrid orbitals is observed. Therefore, # 3
It follows that C—H bonds are present in the sample. # 7
In the Raman spectrum of the sample, the wave number is 2910 cm
^No peak is observed at either the position of ^{-1 or} the position of wave number 2970 cm ^-1 . Instead, the wave number is 3200 cm
A wide OH bond symmetrical expansion and contraction having a peak at the position of ^-1 is recognized. Thus, the # 7 sample results in the absence of C—H bonds, instead of the presence of O—H bonds. In contrast, in the Raman spectrum of the # 1 specimen, both before and after irradiation, the position of the wave number 2910cm ^-1 is observed a large peak of C-H bonds symmetric stretching of sp3 hybrid orbital, the position of the wave number 2970cm ^-1 Shows a large peak of C-H bond antisymmetric stretching of sp3 hybrid orbital. Therefore, it is confirmed that the CH bond is present in the # 1 sample. From the above, when the layer containing the photo-semiconductor and the silicone is irradiated with ultraviolet rays, the organo group bonded to the silicon atom of the silicone molecule represented by the following chemical formula 1 is replaced with the hydroxyl group by photoexcitation of the photo-semiconductor. It is considered that the silicone derivative represented by Chemical Formula 2 is formed on the surface.

[Chemical 1]

[Chemical 2]

Reference Example 4. (Titanium oxide + silicone, titanium oxide content) In order to increase the adhesion to the substrate and obtain better wear resistance, a 10 cm square acrylic resin substrate was previously coated with a silicone layer. That is, in the same manner as in Example 1, A composition and B composition of the coating composition "Glaska" made of Japan Synthetic Rubber
The liquids are mixed in a weight ratio of 3, and the mixed liquid is applied to an acrylic resin substrate and cured at a temperature of 100 ° C.
A plurality of aluminum substrates (# 8 sample) coated with a silicone base coat having a film thickness of 5 μm were obtained. Next, # 8
A thin film made of an optical semiconductor and a silicone resin was formed on the surface of the sample. More specifically, anatase-type titania sol (TA-15, manufactured by Nissan Kagaku Co., Ltd.) and the solution A of "GLASCA" are mixed, diluted with ethanol, and then the solution B of "GLASCA" is added to the titanium oxide-containing silicone coating. A composition for use was prepared. Here, the liquids A and B of "grasca" were adjusted to have a weight ratio of 3. This coating composition was applied to the surface of # 8 sample and cured at a temperature of 100 ° C. to form a top coat composed of anatase-type titania particles and a silicone resin, to obtain # 9 to # 12 samples. The ratio of the weight of the anatase-type titania particles to the total weight of the anatase-type titania particles, the silicone resin and the silica particles in the top coat layer was 5% for the # 9 sample, 10% for the # 10 sample and # 11.
The sample was adjusted to 50% and the # 12 sample was adjusted to 80%. Further, in all the samples, the thickness of the top coat layer was 0.2 μm. BL for # 8 to # 12 samples
While irradiating the B fluorescent lamp with ultraviolet light at an illuminance of 0.5 mW / cm ² for up to 200 hours, the contact angles of the surfaces of these samples with water were measured at different time intervals using a contact angle measuring device (manufactured by ERMA).
And the time change of the contact angle was observed. The results are shown in Figure 5.
Is shown in the graph. As can be seen from the graph of FIG. 5, in the # 8 sample having no optical semiconductor (titanium oxide), there is almost no change in the contact angle with water even when irradiated with ultraviolet rays.
In contrast, with a top coat containing titanium oxide #
It can be seen that the 9 to # 12 samples are hydrophilized until the contact angle with water becomes less than 10 ° in response to ultraviolet irradiation. In particular, # 10 containing 10% by weight or more of titanium oxide
It can be seen that the contact angle with water is 3 ° or less for the ~ 12 samples. Next, in order to examine the photo-oxidation / reduction performance of the # 8 to # 12 samples, the photo-decomposition performance of methyl mercaptan was examined in the same manner as in Example 1. The results are shown in the graph of FIG. As can be seen from the graph of FIG. 6, in this case, the photodegradation performance of methyl mercaptan, that is, the photooxidation reduction performance was suppressed by the addition of silicone, and when the titanium oxide content was 80% by weight or less, 1/5 or less, and 50% by weight or less. It is suppressed to 1/10 or less. In order to further verify this tendency, as a comparative sample, after forming a silica layer on an aluminum substrate (coating the substrate after hydrolysis of tetraethoxysilane and curing by dehydration polycondensation at 150 ° C.), simply anatase-type titania sol ( Nissan Chemical, TA-15)
Sample coated with and baked at 400 ° C (film thickness 0.4 μm)
Was prepared, and the removal rate of methyl mercaptan was measured, but it was very high at 90% (with a TiO ₂ content of 100% in FIG. 6), and the effect of suppressing photo-oxidation reduction performance when a silicone resin was added at a film thickness of 1 μm or less. Was confirmed.

Reference Example 5. (Titanium oxide + silicone, titanium oxide content, pencil hardness) A pencil scratch test was conducted to examine the wear resistance of the top coat made of titanium oxide and silicone. In the same manner as in Example 4, a surface of a 10 cm square acrylic resin substrate was coated with a silicone base coat having a thickness of 5 μm,
Then, top coats having different titanium oxide contents were coated respectively. The proportion of titanium oxide in the top coat is
It was 50% by weight, 60% by weight and 90% by weight. According to Japanese Industrial Standard (JIS) H8602, the surface of the sample was scratched with a pencil lead, and the hardest pencil lead from which the top coat was peeled off was detected. Also, a sample coated with only the base coat was similarly tested. The results are shown in the graph of FIG. The top coat with a titanium oxide content of 90% by weight was peeled off with a pencil lead with a hardness of 5B, but the topcoat with a titanium oxide content of 60% by weight can withstand a pencil lead with a hardness of H and has sufficient abrasion resistance. Increases with decreasing titanium oxide content.

Reference Example 6. (Titanium oxide + sodium, sol system) Anatase type titanium oxide sol (Ishihara Sangyo, STS-1
1) was mixed with an aqueous sodium nitrate solution having a sodium metal concentration of 50 μmol / g to prepare a mixed solution. Here, the molar ratio between the solid content of titanium oxide and the amount of sodium metal in the mixed solution was set to be 87:13. 700 after applying it to the surface of a 15 cm square glazed tile (AB02E01 manufactured by Totou Kikai)
A # 13 sample was obtained by firing at a temperature of ° C for 1 hour. For comparison, anatase type titanium oxide sol (made by Ishihara Sangyo, STS
-11) is a 15 cm square glazed tile surface (A
After coating B02E01), a # 14 sample was obtained which was baked at a temperature of 700 ° C. for 1 hour. The thickness of each of the obtained samples was 0.7 μm. The # 13 sample and # 14 sample after firing were left in a dark place for one week, and then each sample was irradiated with ultraviolet rays for 1 day at an ultraviolet illuminance of 0.15 mW / cm ² using a BLB fluorescent lamp. The changes in the contact angle of each sample with water according to the ultraviolet ray time at this time are shown by the curves # 13 and # 14 in FIG. As can be seen from the comparison between the # 13 curve and the # 14 curve in FIG. 8, the sample surface was hydrophilized by the ultraviolet irradiation regardless of the addition of sodium. Although the reason is not clear, the contact angle tended to be lower when sodium was added. From the above, it can be seen that even if sodium is added to the surface of the base material in addition to the optical semiconductor, it does not adversely affect the hydrophilization phenomenon of the optical semiconductor due to photoexcitation. Next, in order to examine the photo-oxidation / reduction performance of the # 13 and # 14 samples, the photodegradation performance of methyl mercaptan was examined in the same manner as in Example 1.
As a result, the # 14 sample showed a good result of 92%, while the # 13 sample showed 5%. That is, the photoredox performance was very strongly suppressed by the addition of sodium. From the above, it was found that the addition of sodium can suppress the photo-oxidation / reduction performance of the photo-semiconductor by photo-excitation while causing the hydrophilization phenomenon of the photo-semiconductor by photo-excitation.

Reference Example 7. (Titanium oxide + sodium, alkoxide) A mixture of 1 part by weight of tetraethoxy titanium (manufactured by Merck) and 9 parts by weight of ethanol was used as a hydrolysis inhibitor.
A titanium oxide coating solution was prepared by adding 0.1 part by weight of 6% hydrochloric acid, and this solution was applied to the surface of a 10 cm square soda lime glass plate in dry air by a flow coating method. The coating amount is 45 μg / converted to titanium oxide
It was set to cm ² . Since the hydrolysis rate of tetraethoxytitanium is extremely fast, a part of tetraethoxytitanium was hydrolyzed at the coating stage, and titanium hydroxide started to be produced. Next, by holding this glass plate at a temperature of about 150 ° C. for 1 to 10 minutes, the hydrolysis of tetraethoxy titanium is completed, and the produced titanium hydroxide is subjected to dehydration polycondensation to obtain amorphous titanium oxide. Was generated. Thus, a glass plate coated with amorphous titanium oxide was obtained.
This sample was baked at a temperature of 500 ° C. to convert the amorphous titanium oxide into anatase type titanium oxide. It is known that during this firing process, sodium ions, which are alkaline network modifying ions in the glass plate, diffuse from the glass substrate into the titanium oxide coating. After leaving this sample in the dark for several days, the surface of the sample was irradiated with ultraviolet rays for 1 day at an ultraviolet illuminance of 0.5 mW / cm ² using a BLB fluorescent lamp. When the contact angle with water was measured by a contact angle measuring device (manufactured by ERMA), it was hydrophilized to 3 °. From the above, it can be seen that even if sodium is added to the surface of the base material in addition to the optical semiconductor, it does not adversely affect the hydrophilization phenomenon of the optical semiconductor due to photoexcitation. Next, in order to examine the photo-oxidation / reduction performance of the above sample, the photodegradation performance of methyl mercaptan was examined in the same manner as in Example 1. As a result, it was confirmed that it showed no photodegradability of 0% and that the photoredox performance was very strongly suppressed by the addition of sodium. From the above, it was found that even when the film is formed by the alkoxide method, the addition of sodium can suppress the photo-oxidation / reduction performance of the photo-semiconductor by photo-excitation while causing the hydrophilization phenomenon of photo-semiconductor by photo-excitation. did.

Reference Example 8. (Rutile type titanium oxide) 0.1 part by weight of 36% hydrochloric acid as a hydrolysis inhibitor was added to a mixture of 1 part by weight of tetraethoxy titanium and 9 parts by weight of ethanol to prepare a titanium oxide coating solution.
This coating solution was applied to the surface of a 10 cm square quartz glass plate in dry air by a flow coating method. The coating amount was 45 μg / cm ² in terms of titanium oxide. Next, these glass plates are exposed to about 150 minutes for about 150 minutes.
By maintaining the temperature at ℃, tetraethoxy titanium was subjected to hydrolysis and dehydration polycondensation to form a coating film of amorphous titanium oxide on the surface of the glass plate. This sample was fired at a temperature of 800 ° C. to crystallize amorphous titanium oxide. When examined by powder X-ray diffractometry, it was found that the crystal type of the fired sample was the rutile type. The obtained sample was left in the dark for 1 week, and then the surface of the sample was irradiated with ultraviolet rays for 2 days with an ultraviolet illuminance of 0.3 mW / cm ² using a BLB fluorescent lamp. When the contact angle with water was measured with a contact angle measuring instrument (manufactured by ERMA), it was hydrophilized to 0 °. From the above, even when the photo-semiconductor in the layer formed on the substrate surface is rutile-type titanium oxide in which the lower end of the energy level of the conduction band is a positive value, the hydrophilization phenomenon by photo-excitation of the photo-semiconductor does not occur. You can see that it will occur. Next, in order to examine the photo-oxidation / reduction performance of the above sample, the photodegradation performance of methyl mercaptan was examined in the same manner as in Example 1. As a result, it was confirmed that it showed no photodegradability of 0% and no photo-oxidation reduction performance occurred. From the above, even when the photo-semiconductor in the layer formed on the surface of the base material is rutile-type titanium oxide in which the lower end of the energy level of the conduction band is a positive value, photo-oxidation reduction by photo-excitation of the photo-semiconductor It has been found that the hydrophilic phenomenon can be caused by photoexcitation of the optical semiconductor while suppressing the performance.

Reference Example 9. (Tin oxide) Tin oxide sol (manufactured by Taki Chemical Co., Ltd., average crystallite size 3.5 nm)
Is a 15 cm square glazed tile (AB02E0
Apply to the surface of 1) by spray coating method, and
A sample was obtained by firing at a temperature of 50 ° C. for 10 minutes. After leaving the obtained sample in a dark place for one week, an ultraviolet illuminance of 0.3 mW / cm ² was applied to the surface of the sample by using a BLB fluorescent lamp (illuminance of about 0.1 mW /
3 days ultraviolet was irradiated by cm ^2). Contact angle measuring device (E
When the contact angle with water was measured by RMA), it was hydrophilized to 8 °. From the above, even when the photo-semiconductor in the layer formed on the surface of the substrate is tin oxide whose conduction band energy level has a positive lower end, the photo-excitation of the photo-semiconductor causes the hydrophilization phenomenon. I understand. Next, in order to examine the photo-oxidation / reduction performance of the above sample, the photodegradation performance of methyl mercaptan was examined in the same manner as in Example 1. As a result, it was confirmed that it showed no photodegradability of 0% and no photo-oxidation reduction performance occurred. From the above, even when the photo-semiconductor in the layer formed on the surface of the base material is tin oxide whose energy band lower end has a positive value, the photo-oxidation reduction performance by photo-excitation of the photo-semiconductor is improved. It was found that the hydrophilic phenomenon due to the photoexcitation of the photosemiconductor can be caused while suppressing.

Reference Example 10. (Titanium oxide + calcium) Anatase type titanium oxide sol (made by Ishihara Sangyo, STS-1
1) was mixed with a calcium nitrate aqueous solution having a calcium metal concentration of 50 μmol / g to prepare a mixed solution. Here, the molar ratio between the solid content of titanium oxide and the amount of calcium metal in the mixed solution was set to 52:48. 700 after applying it to the surface of a 15 cm square glazed tile (AB02E01 manufactured by Totou Kikai)
A # 15 sample was obtained by firing at a temperature of ° C for 1 hour. The film thickness of the obtained sample was set to 0.7 μm. After firing #
After leaving the 15 samples in the dark for 1 week, the samples were irradiated with ultraviolet rays for 1 day at a UV intensity of 0.15 mW / cm ² using a BLB fluorescent lamp. The change in the contact angle of the sample with water according to the ultraviolet ray time at this time is shown by the # 15 curve in FIG. As can be seen from the comparison between the # 15 curve and the # 14 curve in FIG. 8, the sample surface was hydrophilized by the ultraviolet irradiation regardless of whether calcium was added or not. Although the reason is not clear, the contact angle tended to be lower when calcium was added. From the above, it was found that even if calcium, which was conventionally considered to have a bad influence on the photoredox performance, was added to the surface of the base material, it did not adversely affect the hydrophilization phenomenon of the photosemiconductor by photoexcitation. Therefore, it is considered that the addition of calcium can suppress the photo-oxidation / reduction performance of the photo-semiconductor by photo-excitation, and can cause the hydrophilization phenomenon of photo-semiconductor by photo-excitation.

Reference Example 11. (Titanium oxide + aluminum) Anatase type titanium oxide sol (STS-1 manufactured by Ishihara Sangyo)
1) was mixed with an aqueous aluminum chloride solution having an aluminum metal concentration of 50 μmol / g to prepare a mixed solution. Here, the molar ratio between the solid content of titanium oxide and the amount of aluminum metal in the mixed solution was set to 74:26. After applying it to the surface of a 15 cm square glazed tile (AB02E01 manufactured by Totou Kikai),
A # 16 sample was obtained by firing at a temperature of 700 ° C. for 1 hour. The film thickness of the obtained sample was set to 0.7 μm. The # 16 sample after firing was left in the dark for one week, and then the sample was irradiated with ultraviolet rays for 1 day at a UV intensity of 0.15 mW / cm ² using a BLB fluorescent lamp. The change in the contact angle of the sample with water according to the ultraviolet ray time at this time is shown by the # 16 curve in FIG.
As can be seen from the comparison between the # 16 curve and the # 14 curve in FIG. 8, the sample surface was hydrophilized by the ultraviolet irradiation regardless of the addition of aluminum. Although the reason is not clear, it was confirmed that the contact angle tended to be lower when aluminum was added. From the above, it was found that even if aluminum, which was conventionally considered to have a bad influence on the photo-oxidation / reduction performance, was added to the surface of the base material, it did not adversely affect the hydrophilization phenomenon of the photosemiconductor by photoexcitation. Therefore, it is considered that the addition of aluminum suppresses the photo-oxidation / reduction performance of the photo-semiconductor by photo-excitation, while at the same time causing the hydrophilization phenomenon of photo-semiconductor by photo-excitation.

Reference Example 12. (Titanium oxide + alumina) Anatase type titanium oxide sol (made by Ishihara Sangyo, STS-1
A mixed solution of 1) and boehmite type aluminum oxide sol (Alumina sol-520 manufactured by Nissan Chemical Industries, Ltd.) was prepared. Here, the molar ratio of the titanium oxide solid content and the aluminum oxide solid content in the mixed solution was set to 88:12. A # 17 sample was obtained by coating the surface of a 15 cm square glazed tile (AB02E01 manufactured by Totoki Kiki Co., Ltd.) and baking it at a temperature of 800 ° C. for 1 hour. The film thickness of the obtained sample was set to 0.3 μm. After leaving the # 17 sample after firing in the dark for one week, B
The sample was irradiated with ultraviolet light for 1 day with an illuminance of 0.03 mW / cm ² of ultraviolet light using an LB fluorescent lamp. The # 17 curve in FIG. 8 shows the change in the contact angle of the sample with water depending on the ultraviolet ray time. As can be seen from the comparison between the # 17 curve and the # 14 curve in FIG. 8, the sample surface was hydrophilized by the ultraviolet irradiation regardless of whether or not aluminum oxide was added. Although the reason is not clear, the contact angle tended to be lower when aluminum oxide was added. From the above, even if aluminum oxide, which was conventionally considered to adversely affect the photo-oxidation / reduction performance, is added to the substrate surface,
It was found that there is no adverse effect on the hydrophilization phenomenon caused by photoexcitation of the optical semiconductor. Therefore, while suppressing the photoredox performance by the photoexcitation of the optical semiconductor by the addition of aluminum oxide,
It is considered that the hydrophilic phenomenon can be caused by the photoexcitation of the optical semiconductor.

Reference Example 13. (Titanium oxide + zirconia) Anatase type titanium oxide sol (Ishihara Sangyo, STS-1
1) and zirconium oxide sol (NZS-3 manufactured by Nissan Chemical Industries, Ltd.
A mixed solution of 0B) was prepared. Here, the molar ratio of the solid content of titanium oxide and the solid content of zirconium oxide in the mixed solution is 88: 1.
I set it to 2. A # 18 sample was obtained by coating the surface of a 15 cm square glazed tile (AB02E01 manufactured by Totoki Kiki Co., Ltd.) and baking at a temperature of 800 ° C. for 1 hour. The film thickness of the obtained sample was set to 0.3 μm. The # 18 sample after firing was left in a dark place for one week, and then the sample was irradiated with ultraviolet rays for 1 day at an ultraviolet illuminance of 0.03 mW / cm ² using a BLB fluorescent lamp. The change in the contact angle of the sample with water according to the ultraviolet ray time at this time is shown by the # 18 curve in FIG. As can be seen from the comparison between the # 18 curve and the # 14 curve in FIG. 8, the sample surface was hydrophilized by the ultraviolet irradiation regardless of whether zirconium oxide was added or not. Although the reason is not clear, the contact angle tended to be lower when zirconium oxide was added. From the above, it was found that even if zirconium oxide, which was conventionally considered to have an adverse effect on photooxidation / reduction performance, was added to the surface of the base material, it did not adversely affect the hydrophilization phenomenon due to photoexcitation of the photosemiconductor. Therefore, it is considered that the addition of zirconium oxide can suppress the photo-oxidation / reduction performance of the photo-semiconductor by photo-excitation, and at the same time, cause the hydrophilization phenomenon of photo-semiconductor by photo-excitation.

Reference Example 14. (Titanium oxide + silica) Anatase type titanium oxide sol (made by Ishihara Sangyo, STS-1
1) and silica sol (Snowtex 20 made by Nissan Chemical)
A mixed solution of was prepared. Here, the molar ratio of the titanium oxide solid content and the silica solid content in the mixed solution was set to 88:12. 15 cm square glazed tile (AB02E0 manufactured by Totoki Kikai)
1) After coating on the surface, bake at a temperature of 800 ° C for 1 hour.
19 samples were obtained. The film thickness of the obtained sample was set to 0.3 μm. The # 19 sample after firing was left in the dark for 1 week, and then 0.03 mW / c was applied to the sample using a BLB fluorescent lamp.
Ultraviolet rays were irradiated for 1 day at an ultraviolet illuminance of m ² . The change in the contact angle of the sample with water according to the ultraviolet ray time at this time is shown by the # 19 curve in FIG. As can be seen from the comparison between the # 19 curve and the # 14 curve in FIG. 8, the sample surface was hydrophilized by the ultraviolet irradiation regardless of whether silica was added or not. Although the reason is not clear, the contact angle tended to be lower when silica was added. From the above,
It was found that even if silica, which has been considered to have a bad influence on the photo-oxidation / reduction performance, is added to the surface of the substrate, it does not adversely affect the hydrophilization phenomenon of the photosemiconductor by photoexcitation. Therefore, it is considered that the addition of silica makes it possible to suppress the photo-oxidation / reduction performance of the photo-semiconductor by photo-excitation and to cause the hydrophilization phenomenon of the photo-semiconductor by photo-excitation.

Reference Example 15. (Necessity of Photoexcitation) The # 14 sample of Reference Example 6 and a glazed tile without coating of titanium oxide (AB02E01 manufactured by Toto Kikai Co., Ltd.) for 10 days were left in a dark place, and then a Hg-Xe lamp was used. Then, the time change of the contact angle with water was measured while irradiating with ultraviolet rays under the conditions shown in Table 1 below.

[0047]

[Table 1]

The measurement results are shown in FIGS. 9A to 9C. In A to C, the value plotted with white dots is # 14 of Example 6.
The contact angle of the sample with water is plotted, and the values plotted with black dots represent the contact angle of the glazed tile without titanium oxide coating with water. As can be seen from C, with ultraviolet rays having an energy lower than the wavelength of 387 nm (ultraviolet rays having a wavelength longer than 387 nm) corresponding to the band gap energy of anatase type titanium oxide, even if the ultraviolet rays are irradiated, hydrophilicity does not occur.
On the other hand, as shown in A and B, the wavelength 3 corresponding to the band gap energy of anatase type titanium oxide is
It can be seen that with ultraviolet light having an energy higher than 87 nm, the surface becomes hydrophilic in response to irradiation with ultraviolet light. From the above, it was confirmed that the hydrophilization of the surface is closely related to the photoexcitation of the photosemiconductor.

[0049]

According to the present invention, when a layer containing an optical semiconductor is formed on the surface of a substrate and (1) the hydrogen generation level is set to 0 eV as the optical semiconductor, the energy level of the conduction band is reduced. The lower end is located at a positive value, or (2) the surface further contains a hydrophilic substance that is not an optical semiconductor, so that the optical semiconductor is hardly exposed to the outside air.
(3) Alternatively, by adding a substance that inhibits the photo-oxidation / reduction reaction of the photo-semiconductor to the surface of the photo-semiconductor, the photo-oxidation / reduction reaction is hydrophilized by photoexcitation by irradiation with light having a wavelength not longer than the excitation wavelength of the photo-semiconductor A composite material having a photocatalytic activity that hardly occurs is obtained. If such a composite material is used, it will be superhydrophilic without being photooxidized and deteriorated, and it will be antifouling, antifogging, easy cleanability only with water and rainfall, prevention of water droplet formation, visibility in the rain, biocompatibility, etc. It is possible to form a composite material made of a plastic base material, which has excellent properties. Further, if such a composite material is used, it is not subjected to photoreduction deposition of colored metal ions when used in an aqueous environment, and is superhydrophilized to be antifouling, antifogging, easy cleanability only with water or rainfall, prevention of water droplet formation, It is possible to form a composite material that has excellent visibility in the rain and biocompatibility.

[Brief description of drawings]

FIG. 1 is a graph showing the change over time in the contact angle with water of various samples according to the examples of the present invention due to ultraviolet irradiation.

FIG. 2 is a graph showing the film thickness of various samples and the decomposition performance of methyl mercaptan in Examples of the present invention.

FIG. 3 is an Auger spectroscopic analysis spectrum of an example of the present invention, where (a) is the outermost surface of the sample (b) is 0.02 μm below the outermost surface of the sample, and the cross section (c) in the topcoat layer is 0.02 μm lower than the outermost surface of the sample. To 0.2 μm lower cross-section spectrum in the base coat layer.

FIG. 4 is a Raman spectroscopic analysis spectrum of an example of the present invention.

FIG. 5 is a graph showing the change over time in the contact angle with water of various samples according to the examples of the present invention due to ultraviolet irradiation.

FIG. 6 is a graph showing the titanium oxide content and methyl mercaptan decomposition performance of various samples of the examples of the present invention.

FIG. 7 is a graph showing the results of pencil hardness of various samples of the examples of the present invention.

FIG. 8 is a graph showing changes in contact angle with water of various samples of Examples of the present invention with respect to ultraviolet time.

FIG. 9 is a graph showing the change over time in the contact angle with water when ultraviolet rays of different wavelengths are applied to the surface of the photosemiconductor-containing layer, where A is 313 nm, B is 365 nm, and C is 405 nm.
The graph when it is irradiated with ultraviolet rays.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mitsuyoshi Machida 2-1-1 Nakajima, Kokurakita-ku, Kitakyushu, Fukuoka Prefecture Totoki Equipment Co., Ltd. (72) Inventor Toshiya Watanabe 2 Nakajima, Kokurakita-ku, Kitakyushu, Fukuoka 1st-1st Totoki Co., Ltd. (72) Inventor Makoto Senkoku 2-11-1 Nakajima, Kokurakita-ku, Kitakyushu, Fukuoka Prefecture 72nd Totoki Co., Ltd. (72) Atsushi Kitamura Kitakyushu, Fukuoka 2-1-1 Nakajima, Kokurakita-ku, Totoki Kikai Co., Ltd. (56) Reference JP-A-8-253759 (JP, A) JP-A-9-52973 (JP, A) JP-A-62-191427 ( JP, A) JP-A-7-138021 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B01J 35/02 C09K 3/00 CA (STN) JISST file (JOIS) WPI ( DIALOG)

Claims (2)

(57) [Claims] 1. An optical semiconductor comprising: a base material; and an optical semiconductor formed on the surface of the base material and a layer containing antimony oxide as a substance that inhibits a photoredox reaction of the optical semiconductor.
From tase type titanium oxide, rutile type titanium oxide, tin oxide
A composite material , which is one kind selected from the group consisting of the following, and which is hydrophilized in response to photoexcitation of the optical semiconductor by sunlight. 2. A substrate, an optical semiconductor formed on the surface of the substrate, and a layer made of antimony oxide as a substance that inhibits the photoredox reaction of the optical semiconductor.
-Type titanium oxide, rutile-type titanium oxide, tin oxide
A composite material , which is one kind selected from the group consisting of the following, and which is hydrophilized in response to photoexcitation of the optical semiconductor by sunlight.