JP3104620B2 - Hydrophilic elastic member - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an elastic member made of an elastic material such as rubber or some plastics. In particular, the present invention relates to a hydrophilic elastic member having a hydrophilic surface containing an optical semiconductor and improved so that the surface layer does not peel off or fall off even when the member is deformed.

[0002]

2. Description of the Related Art There has been no proposal to form an optical semiconductor layer mainly composed of ceramics on a surface of an elastic member such as a rubber hose to make it hydrophilic. An object of the present invention is to provide a hydrophilic elastic member which has a hydrophilic surface including an optical semiconductor and is improved so that the surface layer does not peel off or fall off even when the member is deformed. .

[0003]

Means for Solving the Problems In order to solve the above-mentioned problems, a hydrophilic elastic member of the present invention comprises a substrate having elasticity,
A surface layer containing an optical semiconductor formed on the substrate, wherein the member exhibits hydrophilicity in response to photoexcitation of the optical semiconductor; and the surface layer is dispersed in an elastic matrix and the elastic matrix. Characterized by comprising optical semiconductor particles.
Due to the presence of the elastic matrix, the stress accompanying the deformation is reduced, and the destruction of the surface layer can be suppressed.

[0004]

BEST MODE FOR CARRYING OUT THE INVENTION As the material for the elastic matrix, a bifunctional siloxane is preferable. This is because it is rich in elasticity (elasticity) in molecular structure and can withstand oxidation-reduction accompanying the photocatalysis of the optical semiconductor. Examples of other elastic matrix materials include ABS resin, rubber, silicone rubber, PET film, and resin containing a two-dimensional cross-linkable resin.

As an optical semiconductor, titania (Ti
O ₂ ) or the like can be used, but the mixing ratio of the elastic matrix and the optical semiconductor is 10 to 6
Preferably, the optical semiconductor occupies 0%. This is because hydrophilicity and elasticity can be balanced.

A hydrophilic elastic member according to one aspect of the present invention includes a substrate having elasticity, an intermediate layer formed of an elastic material formed on the substrate, and an optical semiconductor formed on the intermediate layer. A surface layer, and a hydrophilic member corresponding to the photoexcitation of the optical semiconductor, characterized in that the intermediate layer and / or the surface layer are thinned.

The intermediate layer is provided with elasticity to prevent the destruction of the intermediate layer and to make the optical semiconductor layer thin so that a large stress is not applied. The thinner the layer, the less stress is generated due to deformation. Further, the thinner the layer, the less stress is generated due to the deformation. Therefore, the thinner the optical semiconductor layer and the intermediate layer, the harder it is to break. Here, it is preferable that the intermediate layer has a photo-oxidation-reduction resistance and functions to protect rubber or plastic as an elastic substrate from a photo-oxidation-reduction reaction of an optical semiconductor. Examples of such materials include silicone-based and fluorine-based resins containing an elastic component such as silicone rubber, fluorine-containing two-dimensional crosslinkable resin, and silicone two-dimensional crosslinkable resin.

[0008] In another aspect of the present invention, a hydrophilic elastic member comprises:
A substrate having elasticity, an intermediate layer formed of an elastic body formed on the substrate, and a surface layer including an optical semiconductor formed on the intermediate layer; Anchor parts are formed at the interface of the layers to increase the bonding strength at the interface, so that the optical semiconductor film breaks down during elastic deformation and even if cracks occur, the semiconductor film does not peel off or fall off, and the deformation is restored It is characterized in that the film is restored to its original state when it becomes. Here, the presence of the intermediate layer is optional.

[0009] Even if the optical semiconductor film is broken and cracked, it is considered that the shape of the film returns to its original shape when the deformation returns to its original state unless the optical semiconductor film is separated or dropped from the substrate. In order to prevent peeling and falling off of the semiconductor film, it is necessary to increase bonding strength by forming an anchor at an interface or the like.

Further, in order to prevent the entire surface of the optical semiconductor film from being broken by a large crack in the surface layer, minute cracks can be formed from the time of forming the semiconductor film.

In the above-described method, if a crack due to deformation naturally occurs, the direction of the crack cannot be controlled.
There is a possibility that a crack may extend to a site where a crack should never occur. If small cracks are formed in the optical semiconductor layer in advance to prevent this, the stress is reduced at the cracks.

Examples of the product field to which the present invention can be applied include plastics for water supply, plastic pipes, rubber hoses, plastics for toys, silicone products for infants, plastics for home appliances, plastics for OA equipment, plastics for automobiles, transmission lines. And housings and cases of recording media (FD, MO, MD, etc.).

Next, the relationship between the optical semiconductor and the hydrophilicity will be described. The present inventors have discovered that the surface of an optical semiconductor is highly hydrophilized when the optical semiconductor is optically excited. That is, when the photoconductive titania is photoexcited with ultraviolet light, the surface is highly hydrophilized so that the contact angle with water is 10 ° or less, more specifically 5 ° or less, especially about 0 °, and It has been discovered that high hydrophilicity is maintained / recovered by light irradiation, and that, under specific conditions, the state of once highly hydrophilized is maintained even in a dark place for 3 weeks or more.

When light having a wavelength higher than the band gap energy of the optical semiconductor is irradiated with sufficient illuminance for a sufficient time, the surface of the optical semiconductor-containing layer becomes superhydrophilic. At present, the phenomenon of superhydrophilization of a surface caused by photoexcitation of an optical semiconductor cannot always be clearly explained. It seems that the superhydrophilization phenomenon by an optical semiconductor is not always the same as the photodecomposition of a substance by a photocatalytic oxidation-reduction reaction conventionally known in the field of application of an optical semiconductor to a chemical reaction. In this regard, the conventional theory of photocatalytic oxidation-reduction reactions is that electron-hole pairs are generated by photoexcitation, and the generated electrons reduce surface oxygen to generate superoxide ions (O ₂ ⁻ ), and generate holes. Oxidizes surface hydroxyl groups to form hydroxyl radicals (.O
H) to produce these highly reactive reactive oxygen species (O
_The substance was decomposed by the oxidation-reduction reaction of ₂ ^-(- OH).

However, the superhydrophilization phenomenon by an optical semiconductor does not agree with the conventional knowledge on photocatalytic decomposition of a substance in at least two respects. First, according to the conventional theory, optical semiconductors such as rutile and tin oxide do not have a sufficiently high energy level of the conductor, so that the reduction reaction does not proceed, and as a result, the electron excited by the conductor Was considered to be excessive, and the electron-hole pairs generated by photoexcitation recombine without participating in the oxidation-reduction reaction. On the other hand, it was confirmed that the hydrophilization phenomenon caused by the optical semiconductor also occurs in optical semiconductors such as rutile and tin oxide.

Second, conventionally, the decomposition of a substance by the photocatalytic oxidation-reduction reaction is performed when the thickness of the optical semiconductor layer is at least 100 nm.
It is thought that it will not happen unless it is over. On the other hand, it has been observed that superhydrophilization by the optical semiconductor occurs even when the thickness of the photocatalyst-containing layer is on the order of several nm.

Therefore, although it cannot be clearly concluded, it is considered that the superhydrophilization phenomenon by the optical semiconductor is a phenomenon slightly different from the photolysis of the substance by the photocatalytic oxidation-reduction reaction. However, it was confirmed that the surface did not become superhydrophilic unless light having an energy higher than the band gap energy of the optical semiconductor was irradiated. Presumably, conduction electrons and holes generated by excitation of the optical semiconductor impart polarity to the surface of the optical semiconductor-containing layer, and water is converted into hydroxyl groups (OH
^It is considered that the surface is made super-hydrophilic because it is chemically adsorbed in the form of-) and a physisorbed water layer is further formed thereon.

Once the surface of the optical semiconductor-containing layer has been highly hydrophilized by photoexcitation, even if the substrate is kept in a dark place,
Surface hydrophilicity lasts for some time. When a contaminant is adsorbed on the surface hydroxyl groups over time and the surface gradually loses superhydrophilicity, the superhydrophilicity is restored by photoexcitation again.

In order to first hydrophilize the optical semiconductor-containing layer, any light source having a wavelength of energy higher than the band gap energy of the optical semiconductor can be used. In the case of an optical semiconductor whose photoexcitation wavelength is located in the ultraviolet region such as titania, the ultraviolet light contained in the sunlight is preferably used under conditions in which the sunlight is applied to the substrate coated with the optical semiconductor-containing layer. be able to. The optical semiconductor can be optically excited by an artificial light source indoors or at night. As will be described later, when the optical semiconductor-containing layer is made of silica-containing titania, it can be easily hydrophilized even with weak ultraviolet light contained in a fluorescent lamp.

After the surface of the optical semiconductor-containing layer is once made superhydrophilic, the superhydrophilicity is maintained by relatively weak light,
Alternatively, it can be recovered. For example, in the case of titania, maintenance and recovery of hydrophilicity can be sufficiently performed even with weak ultraviolet light contained in an indoor lighting lamp such as a fluorescent lamp.

Even if the optical semiconductor-containing layer is extremely thin, it exhibits hydrophilicity, and in particular, the photocatalytic semiconductor material made of metal oxide has sufficient hardness, so that the optical semiconductor-containing layer has sufficient durability and abrasion resistance. Having.

Articles placed in buildings or outdoors are exposed to sunlight during the day, so that the surface of the optical semiconductor-containing layer is highly hydrophilized. In addition, the surface is occasionally exposed to rainfall.
Each time the hydrophilized surface receives rain, dust and contaminants attached to the surface of the substrate are washed away by raindrops, and the surface is self-cleaned.

The surface of the optical semiconductor-containing layer has a contact angle with water of 1
Since it is highly hydrophilized to 0 ° or less, preferably 5 ° or less, and particularly to about 0 °, not only urban dust containing a large amount of lipophilic components, but also inorganic dust such as clay mineral easily from the surface. Washed off. Thus, the surface of the substrate is highly self-purifying by natural action and kept clean.

When the substrate is formed of a non-heat-resistant material such as plastics or when the substrate is coated with a paint, a photo-oxidation-resistant paint containing an optical semiconductor is used as described later. An optical semiconductor-containing layer can be formed by coating and curing the surface.

Optical Semiconductor The optical semiconductor used in the present invention is titania (TiO.sub.2).
₂ ) is most preferred. Titania is harmless, chemically stable, and available at low cost. further,
Titania has a high bandgap energy, so
The photoexcitation requires ultraviolet light and does not absorb visible light in the process of photoexcitation, so that no color is generated by the complementary color component.

As titania, both anatase and rutile can be used. An advantage of anatase titania is that a sol in which very fine particles are dispersed can be easily obtained on the market, and a very thin thin film can be easily formed. Rutile-type titania has a lower conduction band level than anatase-type titania, but can be used for the purpose of superhydrophilization by an optical semiconductor. When the base material is coated with an optical semiconductor-containing layer made of titania, and the titania is photoexcited by ultraviolet light, water is chemically adsorbed on the surface in the form of hydroxyl groups (OH ⁻ ), and a physically adsorbed water layer is formed thereon, As a result, the surface is considered to be superhydrophilic.

Other optical semiconductors usable in the present invention include ZnO, SnO ₂ , SrTiO ₃ , WO ₃ , Bi ₂
There are metal oxides such as O ₃ and Fe ₂ O ₃ . It is considered that these metal oxides easily adsorb surface hydroxyl groups (OH ⁻ ) because metal elements and oxygen exist on the surface, similarly to titania. Further, the particles of the optical semiconductor may be mixed with a metal oxide that is not an optical semiconductor such as silica. In particular, when an optical semiconductor is mixed with silica or tin oxide, the surface can be highly hydrophilized.

As an example of a method for producing such an optical semiconductor layer made of silica-containing titania, precursors of amorphous silica (for example, tetraethoxysilane, tetraisopropoxysilane, tetra-n-propoxysilane, tetrabutoxysilane, tetrabutoxysilane, A mixture of a tetraalkoxysilane such as methoxysilane; a hydrolyzate of silanol; or a polysiloxane having an average molecular weight of 3,000 or less) and a crystalline titania sol is applied to the surface of a substrate, and if necessary, hydrolyzed. After being decomposed to form silanol, the silanol is subjected to dehydration polycondensation by heating at room temperature or, if necessary, to form an optical semiconductor layer in which titania is bound by amorphous silica.

Still another preferred method of forming an optical semiconductor layer exhibiting a high degree of hydrophilicity such that the contact angle with water containing the optical semiconductor-containing silicone coating water is 0 ° is an uncured or partially cured silicone ( The composition is obtained by dispersing particles of an optical semiconductor in a coating film forming element comprising an organopolysiloxane) or a silicone precursor. After applying this composition to the surface of the substrate and curing the coating film forming element, when the optical semiconductor is photoexcited, the organic group bonded to the silicon atom of the silicone molecule is replaced by a hydroxyl group by the action of the optical semiconductor, The surface of the semiconductor-containing layer is highly hydrophilized.

This approach has several advantages. Since the optical semiconductor-containing silicone paint can be cured at room temperature or at a relatively low temperature, it can be applied to non-heat-resistant materials such as plastics and organic substances. This coating composition containing an optical semiconductor can be applied to an existing substrate requiring a highly hydrophilic surface by dipping, brushing, spray coating, roll coating or the like at any time as needed. A high degree of hydrophilization of an optical semiconductor by photoexcitation can be easily performed even with a light source such as sunlight.

Since the optical semiconductor-containing silicone composition has a siloxane bond, it has sufficient resistance to the photooxidation action of the optical semiconductor (optical semiconductor). Still another advantage of the optical semiconductor-containing layer composed of the optical semiconductor-containing silicone coating is that once the surface has been highly hydrophilized, it maintains a high degree of hydrophilicity for a long time even if it is kept in a dark place, and has a fluorescent property. It is to restore a high degree of hydrophilicity even with the light of an interior lighting such as a lamp.

The following bifunctional siloxane precursors can be used as coating film forming elements. That is, dimethyldichlorosilane, dimethyldibromosilane, dimethyldimethoxysilane, dimethyldiethoxysilane; diphenyldichlorosilane, diphenyldibromosilane, diphenyldimethoxysilane, diphenyldiethoxysilane; phenylmethyldichlorosilane, phenylmethyldibromosilane Silane, phenylmethyldimethoxysilane, phenylmethyldiethoxysilane; γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane; γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropyl Methyldiethoxysilane; γ-aminopropylmethyldimethoxysilane, γ-aminopropylmethyldiethoxysilane; γ-mercaptopropylmethyldimethoxysilane γ- mercaptopropyl methyl diethoxy silane; and their partial hydrolyzates; may be used, and mixtures thereof.

In order to ensure good hardness and smoothness of the silicone coating, the three-dimensional cross-linkable siloxane is added in an amount of 10 mol%.
It is preferable to contain the above. Further, in order to provide sufficient flexibility of the coating film while securing good hardness and smoothness, it is preferable to contain 60 mol% or less of the two-dimensional crosslinked siloxane. In order to increase the rate at which the organic group bonded to the silicon atom of the silicone molecule is replaced with a hydroxyl group by photoexcitation, use is made of a silicone in which the organic group bonded to the silicon atom of the silicone molecule is an n-propyl group or a phenyl group. Is preferred. Instead of the silicone having a siloxane bond, an organopolysilazane compound having a silazane bond can be used.

Addition of antibacterial enhancer The optical semiconductor-containing layer can be doped with a metal such as Ag, Cu, or Zn. In order to dope the optical semiconductor with Ag, Cu, or Zn, a soluble salt of these metals is added to the suspension of the optical semiconductor particles, and the optical semiconductor-containing layer is formed using the obtained solution. it can. Alternatively, after forming the optical semiconductor-containing layer, a soluble salt of these metals may be applied, and photoreduced and precipitated by light irradiation.

The optical semiconductor-containing layer doped with Ag, Cu, or Zn can kill bacteria adhering to the surface. Further, this optical semiconductor-containing layer contains molds, algae,
Inhibits the growth of microorganisms such as moss. Therefore, the surface of the member can be kept clean for a long time.

The photo-semiconductor-containing layer added with a photoactivity enhancer is further provided with Pt, Pd, Rh, and Rt.
A platinum group metal such as u, Os, Ir can be doped. Similarly, these metals can be doped into the optical semiconductor by photoreduction precipitation or addition of a soluble salt. When the optical semiconductor is doped with a platinum group metal, the redox activity of the optical semiconductor can be enhanced, and contaminants attached to the surface can be decomposed.

[0037] In photoexcitation, ultraviolet radiation present invention, it is preferable to form an optical semiconductor-containing layer in an optical semiconductor that is photoexcited only by UV having a high band gap energy as titania. Then, the visible light is not absorbed by the optical semiconductor-containing layer, and the member does not emit color due to the complementary color component. Anatase-type titania can be photoexcited with ultraviolet rays of 387 nm or less, rutile-type titania can be 431 nm or less, tin oxide can be 344 nm or less, and zinc oxide can be photoexcited with ultraviolet rays of 387 nm or less.

As the ultraviolet light source, a fluorescent lamp, an incandescent lamp,
Interior lighting such as metal halide lamps and mercury lamps can be used. Under conditions of exposure to sunlight, the optical semiconductor is advantageously naturally photoexcited by the ultraviolet light contained in the sunlight.

In the photoexcitation, the contact angle of the surface with water is about 10 °.
In the following, it is preferably carried out until about 5 ° or less, particularly about 0 °, or it can be carried out. In general, 0.00
By photo-excitation with 1 mW / cm ² ultraviolet illuminance, a high degree of hydrophilicity can be achieved in several days until the contact angle with water becomes about 0 °. Since the illuminance of ultraviolet light contained in sunlight falling on the surface of the ground is about 0.1 to 1 mW / cm ² , the surface can be made highly hydrophilic in a shorter time if exposed to sunlight.

When the optical semiconductor-containing layer is formed of titania-containing silicone, the photocatalyst is photo-excited with sufficient illuminance to replace a sufficient amount of the surface organic groups bonded to the silicon atoms of the silicone molecules with hydroxyl groups. Is preferred.
The most advantageous way to do this is to use sunlight. Once the surface has been highly hydrophilized, the hydrophilicity persists at night. The hydrophilicity is restored and maintained each time it is again exposed to sunlight.

When the elastic member of the present invention is provided to the user, it is desirable that the member is previously made highly hydrophilic.

In the present invention, it is preferable that the elastic member base material is subjected to a protective treatment for protecting the substrate from the photooxidation-reduction reaction by the photocatalysis of the optical semiconductor. Such an idea (weak redox hydrophilization) is based on the discovery that the hydrophilization phenomenon of the member surface by the optical semiconductor and the photooxidation-reduction reaction by the optical semiconductor are basically different phenomena. Based on this finding, the present inventor has found that there is a configuration showing a hydrophilization phenomenon, although the photooxidation-reduction reaction hardly occurs in the design of an optical semiconductor thin film.

In the first embodiment of the weak redox hydrophilization, the energy level of the conduction band of the optical semiconductor is set at 0 eV.
Is to be positioned 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 generated conduction electrons and the oxidation reaction by holes are simultaneously promoted and proceed. Accordingly, tin oxide or rutile, in which the lower end of the energy level of the conduction band of the optical semiconductor is not sufficiently high on the negative side, has a structure in which the reduction reaction by conduction electrons does not easily proceed, and only the oxidation reaction by holes is easily promoted. In such a structure, conduction electrons become excessive, and electron-hole pairs generated by photoexcitation recombine without participating in the oxidation-reduction reaction. Therefore, practically neither oxidation reaction nor reduction reaction occurs. However, the phenomenon of hydrophilization due to photoexcitation proceeds.

When a photooxidation-reduction reaction of an optical semiconductor is used for decomposing organic substances, the decomposition reaction is carried out using water or oxygen in the environment. That is, conduction electrons generated by photoexcitation reduce oxygen to 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 decompose organic substances by photo-oxidative reduction, the energy level at the upper end of the valence band for generating holes is determined by the oxygen generation level (+ 0.82e) at which hydroxyl groups release electrons.
V) if the energy level at the lower end of the conduction band where conduction electrons are generated is located more negative than the hydrogen generation level (0 eV) which hydrogen emits electrons and provides to the oxygen side. It will be good. Therefore, conversely, in order to prevent organic substances from being effectively photooxidized and redox decomposed, the energy level at the upper end of the valence band is located on the negative side of the oxygen generation level (+0.82 eV), or the energy level at the lower end of the conduction band. The level should be located on the positive side of the hydrogen generation level (0 eV).

When the photooxidation-reduction reaction of an optical semiconductor is used for the precipitation of metal ions in water, metal ions are reduced and precipitated by conduction electrons generated by photoexcitation (at the same time, holes oxidize hydroxyl groups in water. Hydroxyl radical (.OH)
Is considered to be generated. ). Therefore, for example, in order to effectively precipitate and remove iron ions from water, the energy level at the bottom of the conduction band where conduction electrons are generated is determined by the iron generation level (−
0.44 eV). Therefore,
Conversely, in order to prevent metal ions from being precipitated from water, the energy level at the bottom of the conduction band should be positioned more positively than the metal generation level. Excluding the noble metal, the metal generation level is on the negative side of the hydrogen generation level, so that the energy level at the bottom of the conduction band should be located on the positive side of the hydrogen generation level (0 eV). Become. The lower end of the energy level of the conduction band that can be used for this is the hydrogen generation level 0e
Examples of the optical semiconductor which is located at a positive value when V is V2 include metal oxides such as tin oxide, tungsten trioxide, bismuth trioxide, ferric oxide, and rutile type titanium oxide.

From the above, as one method for photohydrophilizing while suppressing the decomposition of resin and the precipitation of dissolved metal ions in water, the energy level of the conduction band of the optical semiconductor was set to 0 eV for the hydrogen generation level. In this case, it can be seen that there is a method that is located at a positive value.

In the second embodiment of the weak redox hydrophilization, a layer containing an optical semiconductor and a hydrophilic substance which is not an optical semiconductor is formed on the surface of the substrate, and the optical semiconductor is hardly in contact with the outside air. I do. In such a state, most of the conduction electrons and holes generated by photoexcitation of the optical 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. Then, the excitation light illuminance is 1 mW / cm ² or less, and the amount of conduction electrons and holes generated in the coating film having a small film thickness and / or a low content of optical semiconductor particles is small enough to exhibit sufficient wear resistance. Originally, it can be suppressed to such an extent that a photo-oxidation-reduction reaction hardly occurs. Nevertheless, the photohydrophilization reaction proceeds.

In the third mode of weak oxidation-reduction hydrophilization, a layer is formed on the surface of the base material, the layer containing an optical semiconductor and a substance that inhibits the photooxidation-reduction reaction of the optical semiconductor. Although the mechanism is not clear, alkali metals, alkaline earth metals, alumina, zirconia, silica, antimony oxide, amorphous titanium oxide, aluminum, manganese, etc., weaken the photooxidation-reduction performance of optical semiconductors (“titanium oxide”, Gihodo (199
1)). The amount of conduction electrons and holes generated in a coating film having an excitation light illuminance of 1 mW / cm ² or less and having a film thickness small enough to exhibit sufficient wear resistance and / or having a low content of optical semiconductor particles is also required. And can be suppressed to such an extent that a photo-oxidation-reduction reaction hardly occurs. However, even if these substances are contained in the layer, the photohydrophilization reaction proceeds.

In the second and third embodiments of the weak redox hydrophilicity, the thinner the film, the better. Preferably 1 μm or less,
More preferably, it is 0.2 μm or less. Then, the absolute amount of the optical semiconductor fixed to the base material can be reduced, and the photooxidation-reduction property can be further reduced. Also, the wear resistance is improved. In particular, when the thickness is 0.2 μm or less, it is easy to ensure the transparency of the thin film containing the optical semiconductor, and the design and transparency of the underlayer can be maintained.

In the second mode of weak redox hydrophilization, the content of the optical semiconductor is preferably 5 to 5% with respect to the optical semiconductor-containing layer.
The content is preferably 80% by weight, more preferably about 10 to 50% by weight. This is because the smaller the content of the optical semiconductor, the lower the photooxidation-reduction property. However, since the photohydrophilization phenomenon is also a phenomenon based on the photoexcitation phenomenon of the optical semiconductor, it is necessary that about 5% or more be contained.

In the second and third embodiments of the weak redox hydrophilization, the illuminance of light having a wavelength shorter than the excitation wavelength is preferably 0.0
001 to 1 mW / cm ² , more preferably 0.001 to 1 mW / c
About ² m is good. The lower the illuminance of light of wavelengths below the excitation wavelength,
This is because the amount of generated electron-hole pairs is reduced, so that photooxidation-reduction properties can be reduced. However, since the photohydrophilization phenomenon is also a phenomenon based on the photoexcitation phenomenon of the optical semiconductor, it is about 0.1 μm.
Excitation light illuminance of 0001 mW / cm ² or more is required.

In the present invention, an intermediate layer may be provided between the substrate and the optical semiconductor-containing layer. Thereby, the adhesion to the base material is increased, and the wear resistance is improved.

When the energy level of the conduction band is set to a positive value when the hydrogen generation level is set to 0 eV on the substrate requiring surface hydrophilicity, which is the first mode of the weak oxidation-reduction hydrophilization. For example, the following method is used to form a thin film containing optical semiconductor particles. (1) The above-mentioned optical semiconductor particles are applied to the surface of a base material and fired. (2) On the surface of the base material, an organic compound (alkoxide, chelate, acetate, etc.) or a non-oxide inorganic compound (chloride, sulfate, etc.) containing the constituent element of the photosemiconductor metal oxide is hydrolyzed, The composition is applied to a substrate and subjected to a dehydration reaction by a method such as heating. If the metal oxide is not crystallized like titanium oxide by this process, the metal oxide is further crystallized by heating. (3) The constituent metal of the semiconductor metal oxide is fixed on the surface of the base material by sputtering or the like, and then oxidized by a method such as heating or electrode reaction. If the metal oxide is not crystallized like titanium oxide by this process, the metal oxide is further crystallized by heating.

In the second embodiment of the weak redox hydrophilization, a method of forming a thin film containing optical semiconductor particles and a hydrophilic substance that is not an optical semiconductor on a base material that requires hydrophilicity on the surface is performed by using a hydrophilic material that is not an optical semiconductor. The method differs depending on the type of substance. (I) When the hydrophilic substance that is not an optical semiconductor is an inorganic oxide such as silica or alumina (1) The optical semiconductor particles and the inorganic oxide particles are applied to the surface of a base material and fired. (2) On the surface of the base material, water is added to the photo-semiconductor particles and an organic compound (alkoxide, chelate, acetate, etc.) or a non-oxide inorganic compound (chloride, sulfate, etc.) containing the constituent metal element of the inorganic oxide. The decomposed product is applied to a substrate and subjected to a dehydration reaction by a method such as heating. (3) On the surface of the base material, the inorganic oxide particles and an organic compound (alkoxide,
A hydrolyzate of a non-oxide inorganic compound (e.g., chloride or sulfate) is applied to a substrate, and a dehydration reaction is performed by heating or the like. If the metal oxide is not crystallized like titanium oxide by this process, the metal oxide is further crystallized by heating. (II) In the case of a silicone resin in which at least a part of an organo group in which a hydrophilic substance that is not an optical semiconductor is bonded to a silicon atom is substituted with a hydroxyl group, an optical semiconductor particle and a silicone resin and / or a precursor thereof (organoalkoxysilane, and the like) The hydrolyzate) is applied to a substrate and heated. Thereby, it is hydrolyzed as required, and then dehydration-condensed and polymerized and cured, whereby the optical semiconductor particles and the silicone resin are fixed on the base material. Thereafter, the optical semiconductor is irradiated with light having a wavelength equal to or shorter than the excitation wavelength to replace at least a part of the organo groups bonded to the silicon atoms in the silicone resin with hydroxyl groups.

The third embodiment of the weak redox hydrophilization is a method for forming a thin film containing a substance that inhibits the photooxidation-reduction reaction between the optical semiconductor particles and the optical semiconductor on a substrate that requires surface hydrophilicity. For example, there is the following method. (1) A compound containing the optical semiconductor particles and a metal element constituting the inhibiting substance is applied to the surface of the base material and baked. (2) On the surface of the base material, a compound containing a constituent metal species in an inhibitory substance and an organic compound (alkoxide, chelate, acetate, etc.) containing a constituent metal species of an optical semiconductor particle or an inorganic compound that is not an oxide (chloride) , A sulfated oxide, etc.) is applied to a substrate and subjected to a dehydration reaction by a method such as heating. If the metal oxide is not crystallized like titanium oxide by this process, the metal oxide is further crystallized by heating.

[0056]

Embodiments of the present invention will be described below. Liquid A (silica sol, solid content 13) of anatase type titania sol (manufactured by Nissan Chemical Industries, TA-15, solid 15%, aqueous solvent) and silicone coating composition "Glaska" manufactured by Nippon Synthetic Rubber Co.
%, Mixed solvent of water and alcohol), diluted 18 times (weight ratio) with ethanol, and further added "Glaska" solution B (methyltrimethoxysilane content 98%).
A titania-containing coating composition was prepared. Titania sol (TA-15), silica sol (Solution A) of this coating composition,
Mixing ratio of methyltrimethoxysilane solution (solution B) is 5
6:33:11. The above composition for coating was converted to a PET film (manufactured by Fuji Xerox Co., Ltd., OHP for monochrome PPC).
Film, JF-001), 130 ° C, 30
A film was formed at a temperature of one minute. The thickness of the formed coating film is 0.1μ
m.

[0057] Irregularities may be formed in advance at the interface portion by plasma treatment for anchor formation or the like, and the bonding strength of the layer formed thereon may be increased by the anchor effect.

Formation of Microcracks in Optical Semiconductor Layer The optical semiconductor layer is formed by the same manufacturing method as described above, and the ratio of TiO ₂ and resin to the solvent is adjusted. Alternatively, fine cracks can be formed in the film by plasma treatment or the like after the film is formed.

The film on which the surface layer containing the photocatalyst was formed was bent through a mandrel having a diameter of 10 mm with the photocatalyst layer outside, and the bending resistance was evaluated (JIS K540).
0) As a result, no cracking or peeling was observed in the coating film.

[0060]

As is apparent from the above description, the present invention relates to an elastic member made of an elastic material such as rubber or plastic, which has a hydrophilic surface containing an optical semiconductor and deforms the member. Even if it is performed, it is possible to provide an improved hydrophilic elastic member so that the surface layer does not peel off or fall off.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-9-277463 (JP, A) JP-A-9-226058 (JP, A) JP-A-9-309957 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) B32B 1/00-35/00 B05D 1/00-7/26

Claims (6)

(57) [Claims] 1. A member comprising: a substrate having elasticity; and a surface layer containing an optical semiconductor formed on the substrate, the member exhibiting hydrophilicity in response to photoexcitation of the optical semiconductor; A hydrophilic elastic member, wherein the surface layer has a thickness of 0.2 μm or less, and the surface layer comprises an elastic matrix and optical semiconductor particles dispersed therein. 2. The hydrophilic elastic member according to claim 1, wherein the elastic matrix contains a bifunctional siloxane. 3. An optical semiconductor comprising : a substrate having elasticity; an intermediate layer made of an elastic body formed on the substrate; and a surface layer containing an optical semiconductor formed on the intermediate layer. 2. A hydrophilic elastic member, wherein the surface layer has a thickness of 0.2 μm or less. 4. A member comprising: a substrate having elasticity; and a surface layer containing an optical semiconductor formed on the substrate, the member exhibiting hydrophilicity in response to photoexcitation of the optical semiconductor; The thickness of the surface layer is 0.2 μm or less, an anchor portion or the like is formed at the interface between the base material and the optical semiconductor layer, and the bonding strength at the interface is increased. A hydrophilic elastic member characterized in that the semiconductor film does not peel or fall off when it enters, and the film is restored when the deformation is restored. 5. An optical semiconductor comprising : a base material having elasticity; an intermediate layer formed of an elastic body formed on the base material; and a surface layer containing an optical semiconductor formed on the intermediate layer. A member exhibiting hydrophilicity in response to the light excitation of the above; the thickness of the surface layer is 0.2 μm or less, an anchor portion or the like is formed at the interface between the base material, the intermediate layer, and the optical semiconductor layer; By increasing the bonding strength, the optical semiconductor film is destroyed during elastic deformation and the semiconductor film does not peel or fall off even if cracks occur, and the film is restored when the deformation is restored And a hydrophilic elastic member. 6. The hydrophilic elasticity according to claim 4, wherein minute cracks are formed from the time of forming the optical semiconductor film in order to prevent the entire surface of the optical semiconductor film from being broken by a large crack in the surface layer. Element.