JPH09314750A - Hydrophilic elastic member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a product have a hydrophilic surface containing a photo- semiconductor and to prevent the surface layer from peeling and falling even when a member is deformed. SOLUTION: A hydrophilic elastic member has an elastic backing and a surface layer containing photo-semiconductor which is formed on the backing. The surface of the elastic member indicates a hydrophilic property corresponding to the photo-excitation of the photo-semiconductor. The surface layer is characterized by its composition of an elastic matrix and photo-semiconductor particles dispersed in the matrix. By the existence of the matrix, stress accompanied by deformation is reduced to control the breakage of the surface layer.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an elastic member made of an elastic material such as rubber or some plastics. In particular, it relates to a hydrophilic elastic member which has a hydrophilic surface containing an optical semiconductor and is improved so that the surface layer thereof does not peel 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 made of ceramics on the surface of an elastic member such as a rubber hose to make it hydrophilic. It is an object of the present invention to provide a hydrophilic elastic member which has a hydrophilic surface containing an optical semiconductor and is improved so that the surface layer thereof does not peel or fall off even when the member is deformed. .

[0003]

In order to solve the above problems, a hydrophilic elastic member of the present invention comprises a base material having elasticity,
A surface layer containing an optical semiconductor formed on the base material, the member exhibiting hydrophilicity in response to photoexcitation of the optical semiconductor; the surface layer having an elastic matrix and dispersed therein. It is characterized by comprising a photo-semiconductor particle.
Due to the presence of the elastic matrix, the stress associated with the deformation is reduced, and the destruction of the surface layer can be suppressed.

[0004]

BEST MODE FOR CARRYING OUT THE INVENTION A bifunctional siloxane is suitable as the material for the elastic matrix. This is because the molecular structure is rich in elasticity (elasticity) and can withstand the redox associated with the photocatalytic action of the optical semiconductor. Examples of other elastic matrix materials include ABS resin, rubber, silicon rubber, PET film, and resins containing two-dimensional cross-linking 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% by volume of the surface layer.
It is preferable that the optical semiconductor occupies 0%. This is because the hydrophilicity and elasticity can be balanced.

A hydrophilic elastic member according to one aspect of the present invention includes an elastic base material, an intermediate layer made of an elastic material formed on the base material, and an optical semiconductor formed on the intermediate layer. A surface layer, which exhibits hydrophilicity in response to photoexcitation of the photosemiconductor; wherein the intermediate layer and / or the surface layer is thin.

The intermediate layer is made to have elasticity so as to prevent the intermediate layer from being broken and to make the optical semiconductor layer thin so that a large stress is not applied. The thinner the layer, the smaller the generation of stress due to deformation. Further, the thinner the layer is, the less stress is generated due to the deformation. Therefore, the thinner the optical semiconductor layer and the intermediate layer are, the less likely they are to break. Here, as the intermediate layer, one having photooxidation / reduction resistance and having a function of protecting the rubber or the plastic of the elastic base material from the photooxidation / reduction reaction of the optical semiconductor is preferable. Examples of such a material include silicone rubber, fluorine-containing two-dimensional cross-linking resin, silicone-based and fluorine-based resin containing an elastic component such as silicone two-dimensional cross-linking resin.

A hydrophilic elastic member according to another aspect of the present invention is
An elastic base material, an intermediate layer made of an elastic material formed on the base material, and a surface layer containing an optical semiconductor formed on the intermediate layer, the base material, the intermediate layer, and the optical semiconductor. Anchors are formed at the interface of the layers to increase the bonding strength of the interface so that the photosemiconductor film is destroyed during elastic deformation, and even if cracks occur, the semiconductor film does not peel off or fall off and the deformation is restored. The feature is that the film will be restored when it becomes. The presence of the intermediate layer is optional here.

Even if the optical semiconductor film is broken and cracked, the shape of the film is considered to be restored when the deformation is restored unless it is separated or dropped from the base material. In order to prevent peeling / falling off of the semiconductor film, it is necessary to increase the bonding strength by forming an anchor at the interface.

Further, in order to prevent a large crack from being formed in the surface layer and the entire optical semiconductor film from breaking, it is possible to form a minute crack from the time of forming the semiconductor film.

In the above-mentioned method, when a crack due to deformation naturally occurs, the direction of the crack cannot be controlled.
There is a possibility that the crack may extend to the part that should never crack. In order to prevent this, if a minute crack is formed in the optical semiconductor layer in advance, the stress is relieved at the crack portion.

Examples of the product fields to which the present invention can be applied include plastics for water supply, resin pipes, rubber hoses, plastics for toys, silicone products for infants, plastics for home appliances, plastics for office automation equipment, plastics for automobiles, and power transmission lines. Examples of the coating resin, tires, housings and cases for recording media (FD, MO, MD, etc.) can be mentioned.

Next, the relationship between the optical semiconductor and hydrophilicity will be described. The present inventor discovered that the surface of an optical semiconductor is highly hydrophilized when the optical semiconductor is photoexcited. That is, when the photo-semiconductive titania is photoexcited with ultraviolet rays, the surface is highly hydrophilized so that the contact angle with water is 10 ° or less, more specifically 5 ° or less, and particularly about 0 °, and It was discovered that irradiation with light maintains and restores a high degree of hydrophilicity, and that under certain conditions, a highly hydrophilized state is maintained even in a dark place for 3 weeks or longer.

When light having a wavelength of energy higher than the band gap energy of the photosemiconductor is irradiated with sufficient illuminance for a sufficient time, the surface of the photosemiconductor-containing layer becomes superhydrophilic. At present, the surface superhydrophilization phenomenon caused by photoexcitation of an optical semiconductor cannot always be clearly explained. The superhydrophilization phenomenon by the photo-semiconductor does not seem to be the same as the photo-decomposition of a substance by the photocatalytic redox reaction conventionally known in the field relating to the application of the photo-semiconductor to the chemical reaction. In this regard, conventional dogma regarding the photocatalytic redox reaction is photoexcited by electron - hole pairs are generated, the generated electrons are superoxide ions by reducing surface oxygen (O ₂ ^-) to generate the hole Oxidize the hydroxyl groups on the surface to generate hydroxyl radicals (・ O
H) to produce these highly reactive reactive oxygen species (O
₂ ^- material by an oxidation-reduction reaction of and · OH) was intended that they are degraded.

However, the superhydrophilization phenomenon by the photo-semiconductor is inconsistent with the conventional knowledge about the photocatalytic decomposition of substances in at least two respects. First, according to the conventional theory, in photo semiconductors such as rutile and tin oxide, the energy level of the conductor is not sufficiently high, so the reduction reaction does not proceed, and as a result, the electrons photoexcited by the conductor are not excited. It was thought that the electron-hole pairs generated by photoexcitation recombine without participating in the redox reaction. On the other hand, it was confirmed that the hydrophilization phenomenon caused by the optical semiconductor also occurs in the optical semiconductors such as rutile and tin oxide.

Secondly, conventionally, the decomposition of a substance by a photocatalytic oxidation-reduction reaction is carried out when the thickness of the optical semiconductor layer is at least 100 nm
It is thought that it will not happen unless it is above. On the other hand, it was observed that the superhydrophilization by the photo-semiconductor occurs even when the film thickness of the photocatalyst containing layer is on the order of several nm.

Therefore, although it cannot be concluded clearly, it is considered that the superhydrophilization phenomenon by the photo-semiconductor is a phenomenon slightly different from the photodecomposition of the substance by the photocatalytic redox reaction. However, it was confirmed that superhydrophilization of the surface does not occur unless light having an energy higher than the band gap energy of the optical semiconductor is irradiated. Probably, the conduction electrons and holes generated by the excitation of the photo-semiconductor impart polarities to the surface of the photo-semiconductor-containing layer, and water becomes a hydroxyl group (OH
^It is thought that the surface becomes superhydrophilic by chemical adsorption in the form of-), and a physically adsorbed water layer is formed on it.

Once the surface of the photosemiconductor-containing layer has been made highly hydrophilic by photoexcitation, even if the substrate is kept in a dark place,
The hydrophilicity of the surface lasts for some time. When the contaminant is adsorbed on the surface hydroxyl groups with the passage of time and the surface gradually loses the superhydrophilic property, the superhydrophilic property is restored by photoexcitation again.

In order to first hydrophilize the photosemiconductor-containing layer, any light source having a wavelength of energy higher than the band gap energy of the photosemiconductor can be used. In the case of an optical semiconductor in which the photoexcitation wavelength is located in the ultraviolet region such as titania, under the condition that sunlight hits the substrate coated with the optical semiconductor-containing layer, the ultraviolet rays contained in the sunlight are preferably used. be able to. An 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 made hydrophilic even with weak ultraviolet rays contained in a fluorescent lamp.

After the surface of the photosemiconductor-containing layer is once made superhydrophilic, the superhydrophilicity is maintained by relatively weak light,
Alternatively, it can be restored. For example, in the case of titania, the hydrophilicity can be sufficiently maintained and restored even with weak ultraviolet rays contained in an interior illumination lamp such as a fluorescent lamp.

The photo-semiconductor-containing layer exhibits hydrophilicity even when it is very thin, and in particular, the photo-catalytic semiconductor material made of a metal oxide has sufficient hardness, so that the photo-semiconductor-containing layer has sufficient durability and abrasion resistance. Have.

Since an article placed in a building or outdoors is exposed to sunlight during the day, the surface of the photosemiconductor-containing layer is highly hydrophilized. Moreover, the surface is occasionally exposed to rainfall.
Every time the hydrophilized surface receives rainfall, the dust and contaminants adhering 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, especially about 0 °, not only urban soot dust containing a large amount of lipophilic components but also inorganic dust such as clay minerals can be easily removed from the surface. Washed away. In this way, the surface of the substrate is highly self-cleaned and kept clean by the action of nature.

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

Examples of the optical semiconductor for use in optical semiconductor present invention, titania (TiO
₂ ) is most preferred. Titania is harmless, chemically stable, and available at low cost. further,
Titania has a high band gap energy, so
Ultraviolet light is required for photoexcitation, and since visible light is not absorbed in the process of photoexcitation, color development by the complementary color component does not occur.

As titania, both anatase and rutile can be used. The advantage of the anatase type 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. Although rutile type titania has a lower conduction band level than that of anatase type, it can be used for the purpose of superhydrophilization by an optical semiconductor. The substrate coated with the optical semiconductor-containing layer made of titania, the titania photoexcited by UV light, water is a hydroxyl group (OH ^-) are chemisorbed on the surface in the form of, formed more physically adsorbed water layer thereon, As a result, it is considered that the surface becomes superhydrophilic.

Other optical semiconductors that can be used in the present invention include ZnO, SnO ₂ , SrTiO ₃ , WO ₃ and Bi _2.
There are metal oxides such as O ₃ and Fe ₂ O ₃ . It is considered that these metal oxides are likely to adsorb the surface hydroxyl group (OH ⁻ ) because the metal element and oxygen are present on the surface similarly to titania. Also, particles of an 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 the method for producing an optical semiconductor layer made of such silica-containing titania, a precursor of amorphous silica (for example, tetraethoxysilane, tetraisopropoxysilane, tetra n-propoxysilane, tetrabutoxysilane, tetra A mixture of tetraalkoxysilane such as methoxysilane; silanol which is a hydrolyzate thereof; or polysiloxane having an average molecular weight of 3,000 or less) and crystalline titania sol is applied to the surface of the substrate, and hydrolyzed as necessary. After decomposing 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 with amorphous silica.

Still another preferred way of forming a photosemiconductor layer exhibiting a high degree of hydrophilicity such that the contact angle with water of the silicone paint containing photosemiconductor is 0 ° is an uncured or partially cured silicone ( It is to use a composition in which photo-semiconductor particles are dispersed in a film-forming element composed of an organopolysiloxane) or a silicone precursor. When this composition is applied to the surface of a base material and the film-forming element is cured, and then the photo-semiconductor is photoexcited, the organic group bonded to the silicon atom of the silicone molecule is replaced with a hydroxyl group by the action of the photo-semiconductor, The surface of the semiconductor-containing layer is highly hydrophilized.

There are several advantages to this approach. Since the photo-semiconductor-containing silicone coating can be cured at room temperature or a relatively low temperature, it can be applied to non-heat resistant materials such as plastics and organic materials. This coating composition containing an optical semiconductor can be applied to an existing substrate that requires a highly hydrophilic surface by dipping, brush coating, spray coating, roll coating, or the like at any time as necessary. The high degree of hydrophilization of a photo-semiconductor by photoexcitation can be easily performed even with a light source such as sunlight.

Since the photo-semiconductor-containing silicone composition has a siloxane bond, it has sufficient resistance to the photo-oxidation action of the photo-semiconductor (photo-semiconductor). Still another advantage of the photo-semiconductor-containing layer made of the photo-semiconductor-containing silicone coating is that once the surface is made highly hydrophilic, it retains a high degree of hydrophilicity for a long period of time even when kept in a dark place, and has a high fluorescence. It is to restore a high degree of hydrophilicity even with the light of an interior lighting lamp such as a lamp.

The following bifunctional siloxane precursors can be used as the film-forming element. 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, 10 mol% of three-dimensional cross-linking siloxane is used.
It is preferable to contain the above. Further, in order to provide sufficient flexibility of the coating film while ensuring good hardness and smoothness, it is preferable to contain the two-dimensional crosslinked siloxane in an amount of 60 mol% or less. Further, 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 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 an optical semiconductor with Ag, Cu, or Zn, soluble salts of these metals are added to a suspension of optical semiconductor particles, and the resulting solution is used to form an optical semiconductor-containing layer. it can. Alternatively, after forming the photo-semiconductor-containing layer, soluble salts of these metals may be applied and photo-reduced to be precipitated by light irradiation.

The photo-semiconductor-containing layer doped with Ag, Cu, or Zn can kill bacteria attached to the surface. Further, this optical semiconductor-containing layer is a mold, algae,
Inhibits the growth of moss-like microorganisms. Therefore, the surface of the member can be kept clean for a long period of time.

Addition of photoactivity enhancer The photo-semiconductor-containing layer is further provided with Pt, Pd, Rh and R.
It can be doped with platinum group metals such as u, Os, Ir. 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.

Photoexcitation / Ultraviolet Irradiation In the present invention, it is preferable to form the optical semiconductor-containing layer from an optical semiconductor such as titania which has a high band gap energy and is photoexcited only by ultraviolet rays. By doing so, visible light is not absorbed by the optical semiconductor-containing layer, and the member does not develop color due to the complementary color component. Anatase-type titania can be photoexcited with ultraviolet rays having a wavelength of 387 nm or less, rutile-type titania of 431 nm or less, tin oxide of 344 nm or less, and zinc oxide 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 the conditions of exposure to sunlight, the photosemiconductor is naturally spontaneously photoexcited by the ultraviolet rays contained in sunlight.

Photoexcitation has a contact angle of about 10 ° with water on the surface.
The following can be performed or can be performed until the temperature is preferably about 5 ° or less, particularly about 0 °. In general, 0.00
Photoexcitation with an ultraviolet illuminance of 1 mW / cm ² enables highly hydrophilic treatment until the contact angle with water becomes approximately 0 ° in a few days. Since the illuminance of ultraviolet rays contained in sunlight falling on the surface of the earth is about 0.1 to 1 mW / cm ² , the surface can be made highly hydrophilic in a shorter time by exposing to sunlight.

When the photo-semiconductor-containing layer is formed of titania-containing silicone, the photocatalyst is photoexcited with sufficient illuminance so that the surface organic group bonded to the silicon atom of the silicone molecule is replaced with a hydroxyl group in a sufficient amount. 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 providing the elastic member of the present invention to the user, it is desirable that the member is highly hydrophilic in advance.

In the present invention, it is preferable that the elastic member base material is subjected to a protective treatment for protecting it from the photo-oxidation-reduction reaction due to the photocatalytic action of the optical semiconductor. Such a concept (weak redox hydrophilicity) is based on the discovery that the phenomenon of hydrophilicity of the surface of a member by an optical semiconductor is basically different from the photooxidation / reduction reaction by an optical semiconductor. Based on this finding, the present inventor has found out that there is a structure exhibiting a hydrophilization phenomenon, although the photo-semiconductor thin film shows almost no photo-oxidation-reduction reaction due to its design.

In the first mode of weak redox hydrophilicity, the energy level of the conduction band of the optical semiconductor and the hydrogen generation level are 0 eV.
Then, it is to 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, 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-redox reaction of a photo-semiconductor is used for the deposition of metal ions in water, the conduction electrons generated by photoexcitation cause reduction and deposition of metal ions (at the same time, holes oxidize hydroxyl groups in water). Hydroxyl radical (・ OH)
Is considered to generate. ). Therefore, for example, in order to effectively remove iron ions from water, the energy level at the bottom of the conduction band generated by conduction electrons is the iron generation level (−
It must be located on the negative side of 0.44 eV). Therefore,
On the contrary, in order to prevent the 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. Excluding noble metals, the production level of metal is on the negative side of the hydrogen production level, so in the end, the energy level at the bottom of the conduction band should be located on the positive side of the hydrogen production level (0 eV). Become. The lower end of the energy level of the conduction band that can be used for this is 0e for the hydrogen generation level.
Examples of the optical semiconductor having a positive value when V is a metal oxide such as tin oxide, tungsten trioxide, dibismuth trioxide, ferric oxide, and rutile-type titanium oxide.

From the above, as one method of photohydrophilization while suppressing decomposition of resin and 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 second mode of weak redox hydrophilicization, 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 in a state where it is not in contact with the outside air. To do. 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.

In the third mode of weak redox hydrophilicity, 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, amorphous titanium oxide, aluminum, manganese, etc. weaken the photooxidation / reduction performance of the optical semiconductor (“titanium oxide”, Gihodo (199
1)). Also, 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 a thickness that is thin enough to exhibit sufficient abrasion resistance and / or a low content of optical semiconductor particles. With, it becomes possible to suppress photooxidation reduction reaction to the extent that it hardly occurs. However, the photohydrophilization reaction proceeds even if these substances are contained in the layer.

In the second and third aspects of weak redox hydrophilicity, it is preferable that the film thickness is thin. Preferably 1 μm or less,
More preferably, it is 0.2 μm or less. 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, it is easy to secure the transparency of the thin film containing an optical semiconductor, and the design and transparency of the base can be maintained.

In the second embodiment of weak redox hydrophilicity, the photo-semiconductor content is preferably 5 to the photo-semiconductor-containing layer.
The amount is preferably 80% by weight, more preferably 10 to 50% by weight. 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 second and third modes of weak redox hydrophilicity, the illuminance of light having a wavelength of the excitation wavelength or less is preferably 0.0
001 to 1 mW / cm ² , more preferably 0.001 to 1 mW / c
About m ² is good. The lower the illuminance of wavelength light below the excitation wavelength,
This is because the amount of generated electron-hole pairs is reduced, so that the photoredox property can be lowered. However, since the photohydrophilization phenomenon is also a phenomenon based on the photoexcitation phenomenon of an optical semiconductor, it is about 0.
Excitation light illuminance of 0001 mW / cm ² or more is required.

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.

The energy level of the conduction band on the base material requiring hydrophilicity of the surface, which is the first mode of weak redox hydrophilicity, is located at a positive value when the hydrogen generation level is 0 eV. The method for forming a thin film containing optical semiconductor particles is as follows. (1) The above-mentioned optical semiconductor particles are applied to the surface of the base material and baked. (2) The surface of the substrate is hydrolyzed with an organic compound (alkoxide, chelate, acetate, etc.) containing a constituent element of the photo-semiconductor metal oxide (alkoxide, chelate, acetate, etc.) or an inorganic compound (chloride, sulfate, etc.) that is not an oxide, It is 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.

A method of forming a thin film containing photo-semiconductor particles and a hydrophilic substance which is not a photo-semiconductor on a substrate which requires hydrophilization of the surface, which is a second mode of weak redox hydrophilicity, is a hydrophilicity which is not a photo-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) Optical semiconductor particles and the above inorganic oxide particles are applied to the surface of a base material and baked. (2) The photo-semiconductor particles and the organic compound (alkoxide, chelate, acetate, etc.) containing the constituent element metal species of the above-mentioned inorganic oxide or non-oxide inorganic compound (chloride, sulfate, etc.) is added to the surface of the base material. 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 above-mentioned inorganic oxide particles and an organic compound (alkoxide, which contains a metal species of the constituent element of the optical semiconductor particles,
A chelate, acetate, etc.) or a hydrolyzate of an inorganic compound that is not an oxide (chloride, sulfate, etc.) is 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. (II) In the case of a silicone resin in which a hydrophilic substance that is not a photo-semiconductor is substituted with at least a part of a silicon atom-bonded organo group by a hydroxy group: photo-semiconductor particles 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.

A method of forming a thin film containing photo-semiconductor particles and a substance that inhibits the photo-oxidation / reduction reaction of a photo-semiconductor on a substrate which requires hydrophilization of the surface, which is the third mode of weak redox hydrophilicity, For example, there are the following methods. (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) On the surface of the base material, a compound containing the constituent element metal species in the inhibiting substance and an organic compound (alkoxide, chelate, acetate, etc.) containing the constituent element metal species of the optical semiconductor particles or an inorganic compound that is not an oxide (chlorination) A hydrolyzate of a product, a sulfate, etc.) is applied to a base material, and a 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.

[0056]

Embodiments of the present invention will be described below. Anatase type titania sol (manufactured by Nissan Kagaku Co., TA-15, solid content 15%, water solvent) and liquid A (silica sol, solid content 13 of silica coating composition "GLASCA" manufactured by Japan Synthetic Rubber Co., Ltd.
%, A mixed solvent of water and alcohol) and diluted 18 times (weight ratio) with ethanol, and then added "Glaska" solution B (methyltrimethoxysilane content 98%),
A titania-containing coating composition was prepared. Titania sol (TA-15), silica sol (liquid A) of this coating composition,
Mixing ratio of methyltrimethoxysilane solution (B solution) is 5
It was 6:33:11. A PET film (manufactured by Fuji Xerox Co., Ltd., OHP for monochrome PPC)
Film, JF-001), 130 ° C, 30
The film was formed at a temperature of minutes. The thickness of the formed coating film is 0.1μ
m.

Anchor formation By plasma treatment or the like, it is possible to make unevenness in advance in the place which becomes the interface part, and to make the bonding strength of the layer formed thereon stronger by the anchor effect.

Formation of microcracks in optical semiconductor layer Produced by the same manufacturing method as described above, the ratio of TiO ₂ and resin to the solvent is adjusted. Alternatively, microcracks can be formed in the film by plasma treatment or the like after forming the film.

The film on which the surface layer containing the photocatalyst was formed was bent with a photocatalyst layer on the outside through a mandrel having a diameter of 10 mm to evaluate the bending resistance (JIS K 540).
As a result, the coating film was not cracked or peeled.

[0060]

As is apparent from the above description, the present invention is an elastic member made of an elastic material such as rubber or plastic, having a hydrophilic surface containing an optical semiconductor and deforming the member. It is possible to provide a hydrophilic elastic member improved so that the surface layer does not peel or fall off even if it is carried out.

Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical display location C08L 101/00 KAE C08L 101/00 KAE

Claims (8)

[Claims] 1. A member comprising an elastic base material and a surface layer containing an optical semiconductor formed on the base material, the member exhibiting hydrophilicity in response to photoexcitation of the optical semiconductor; A hydrophilic elastic member, wherein 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. A hydrophilic elastic member whose surface layer containing an optical semiconductor has a thickness of 1 μm or less. 4. An optical semiconductor, comprising: a base material having elasticity; an intermediate layer made 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 photoexcitation; and a hydrophilic elastic member having a thin surface layer. 5. The hydrophilic elastic member according to claim 4, wherein the surface layer has a thickness of 1 μm or less. 6. A member comprising an elastic base material and a surface layer containing an optical semiconductor formed on the base material, the member exhibiting hydrophilicity in response to photoexcitation of the optical semiconductor; Anchors, etc. are formed at the interface between the material and the optical semiconductor layer,
By increasing the bonding strength at the interface, the optical semiconductor film is destroyed during elastic deformation, and even if cracks occur, the semiconductor film does not peel off or fall off, and the film returns to its original state when the deformation is restored. And a hydrophilic elastic member. 7. A base material having elasticity, an intermediate layer made of an elastic body formed on the base material, and a surface layer containing an optical semiconductor formed on the intermediate layer, An anchor portion or the like is formed at the interface between the intermediate layer and the optical semiconductor layer to increase the bonding strength at the interface, the optical semiconductor film is destroyed during elastic deformation, and the semiconductor film does not peel or fall off even if a crack occurs, A hydrophilic elastic member characterized in that when the deformation is restored, the film is also restored. 8. The hydrophilic elastic member according to claim 6, wherein minute cracks are formed from the time of forming the semiconductor film in order to prevent the entire surface of the photosemiconductor film from breaking due to large cracks in the surface layer. .