Coating material for photocatalyst film, method of manufacturing the coating material, and cleaning method and cleaning device using the coating material

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention relates to a photocatalytic membrane coating material having high photocatalytic activity and excellent durability (adhesion) and a method for producing the same, and a pollutant purification method and apparatus using these photocatalytic membrane coating materials.

【0002】

[Conventional technology]

It is known that titanium oxide has an action of generating radicals by irradiation with ultraviolet rays having a wavelength of 400 nm or less, that is, photocatalytic properties, and can decompose organic substances by the action of oxidizing these radicals. Utilizing such photocatalytic properties, studies are being actively conducted to purify trace pollution in the air or water, and to decompose dirt and bacteria on the surface of the material.

【0003】

There are three types of titanium oxide crystal structure: high-temperature rutile type and low-temperature anatase type, which belong to the tetragonal system, and oblique brookite type. Of these, the most common is the tetragonal type. There are two crystalline types (rutile type and anatase type). Among them, the former anatase-type titanium oxide crystal powder exhibits high photocatalytic properties, and the latter rutile-type titanium oxide crystal powder is known to be inferior in photocatalytic properties to anatase-type titanium oxide crystal powder (). CMC "Hikari Clean Revolution"; p116 ~ 118). Therefore, a method of purifying trace pollutants in the air or water by utilizing the photocatalytic property of anatase-type titanium oxide and decomposing stains and bacteria on the surface of the material is being actively studied.

【0004】

Since titanium oxide is generally supplied as a powder, attempts to remove contamination by using the powder itself are being considered, but the titanium oxide powder is scattered in the air and after treatment in a liquid. Problems such as difficulty in separating and removing powders arise. Therefore, when titanium oxide powder is used as a photocatalyst in actual applications, it is desirable to thin the titanium oxide and immobilize it on some material (supporting material).

【0005】

As a method of thinning titanium oxide and immobilizing it on the supporting material, a method of coating on the supporting material with an inorganic binder such as silica that is not decomposed by a photocatalytic reaction is known. In addition, a method of sintering using an organic binder such as a fluororesin type or a silicone type is also used (Kogyo Chosakai "World of Photocatalysts", p45-48). However, the use of a binder is not preferable from the viewpoint of catalytic activity because the effective surface of the titanium oxide powder is covered.

【0006】

Therefore, it is conceivable to form a thin film made of only titanium oxide directly on the supporting material. Therefore, vapor phase coating (PVD) such as vapor deposition, sputtering, holocathode type ion plating, and arc type ion plating is being studied. These methods are attracting attention as techniques that can solve the problems of insufficient photocatalyst characteristics and insufficient durability due to the above-mentioned binder method.

【0007】

For example, according to PVD, there is an advantage that a titanium oxide photocatalyst film can be formed directly from the gas phase, and higher adhesion can be obtained as compared with a general film forming method. Furthermore, PVD can be formed at a relatively low temperature and the treatment time is short compared to the above-mentioned method of applying and firing an organic titanium compound solution, so that the diffusion of substrate atoms into the titanium oxide photocatalyst film is minimal. As a result of being suppressed to the limit, there is also an advantage that high photocatalyst characteristics can be obtained.

【0008】

As described above, the use of PVD has an advantage that a titanium oxide film having excellent photocatalytic properties is formed with good adhesion as compared with other methods. However, since it is the film formed by PVD, it is not possible to secure the same effective reaction surface area as when titanium oxide powder is used, and the same photocatalytic property as anatase-type titanium oxide crystal powder can be obtained. The reality is that it has not been done.

【0009】

Furthermore, the application of titanium oxide to the purification process of air and liquid requires extremely high photocatalytic property levels, and it is assumed that it is treated with anatase-type titanium oxide powder, which is considered to have the highest catalytic property level so far. Is often inadequate. Therefore, it is desired to provide a new titanium oxide photocatalyst technology that can be applied to the purification process.

【0010】

Further, in order to improve the photocatalytic properties of the titanium oxide film, an attempt to orient the titanium oxide crystal in the photocatalytic film has been studied. For example, Japanese Patent Application Laid-Open No. 11-197516 discloses that photocatalytic properties are improved by aligning the priority growth planes (001) of anatase-type titanium oxide. However, even with this technique, photocatalytic properties superior to those of anatase-type titanium oxide powder have not been obtained, and there is room for improvement.

【0011】

On the other hand, as a method of directly forming titanium oxide as a film, an organic titanium compound solution [alkoxide (isopropoxide, butoxide, etc.) in which alcohol is bound to Ti, acetylacetonate, etc.] is applied to the base material, and 400 ° C. A method of firing at a high temperature of C or higher is also known (Industrial Research Council "The World of Photocatalysts", p51-52). According to this method, when titanium oxide is formed, the constituent atoms of the base material, the Ti atoms in the film, and the O atoms in the atmosphere are mutually diffused between the interface between the film and the base material, and as a result, high adhesion can be obtained. it can. Further, according to the above method, since the entire surface is occupied by titanium oxide, there is an advantage that the photocatalytic property is improved as compared with the method of fixing the titanium oxide powder with a binder.

【0012】

However, in the above method, when a base material such as a metal base material in which base material elements are easily diffused is used, non-Ti atoms (metal atoms) invade the titanium oxide film as impurities, and the titanium oxide Inhibition of crystal growth can occur. In addition, an impurity level is formed between the band gaps that cause photocatalytic action, and this level becomes a recombination site of electrons and holes, and a large amount of electrons and holes disappear, so that the photocatalytic reaction efficiency (Industrial Research Council "The World of Photocatalysts", p122 ~ 123).

【0013】

Therefore, in the titanium oxide film, studies have been made to prevent recombination of electrons and holes generated by photocatalytic action and to suppress a decrease in oxidation resolution due to holes. That is, as shown in FIG. 1 (a), when electrons and holes are present in the vicinity of the membrane, a part of both is recombined and the holes are neutralized and extinguished. .. In order to prevent the loss of holes (decrease in catalytic ability) due to such neutralization disappearance, a metal that easily causes a reduction reaction (reduction reaction promoting metal) is allowed to exist on the titanium oxide film (Fig. 1). (b)), there is a solution to separate and localize holes and electrons (charge separation) (Fig. 1 (c)). The photocatalytic action causes a reduction reaction by electrons at the same time as an oxidation reaction by holes, but when a reduction reaction promoting metal is attached on the titanium oxide film, the reduction reaction occurs intensively here and the reduction reaction site is formed. As it is formed, the electrons are attracted to this reduction reaction site and separated from the holes. Therefore, the recombination of holes and electrons can be suppressed.

【0014】

However, if the reduction reaction promoting metal is simply adhered onto the titanium oxide film, the metal will fall off due to an external force, and it will be difficult to localize the electrons over a long period of time. In particular, when the physical load applied to the titanium oxide film is large as in water treatment, metal loss becomes remarkable, and improvement measures have been sought.

【0015】

[Problems to be Solved by the Invention]

Therefore, the ultimate object of the present invention is to provide a photocatalyst film coating material in which a titanium oxide film having excellent photocatalytic activity is formed on a substrate with good adhesion. The first issue was to provide a novel photocatalyst film coating material having extremely high photocatalytic properties exceeding the photocatalytic level of anatase-type titanium oxide crystal powder and having excellent durability. Further, the second object is to provide a photocatalyst film coating material having high photocatalytic properties by preventing the recombination of electrons and holes as described above and improving the adhesion. Furthermore, finding a method for relatively easily producing each photocatalyst film coating material is a third and fourth task, and providing a purification method using these photocatalyst film coating materials is a fifth task, and purification is performed. The sixth issue is the provision of equipment.

【0016】

[Means for solving problems]

According to the first invention of the present application, which solves the first problem, in a photocatalyst film coating material in which a photocatalyst film containing titanium oxide is laminated on at least one side of a base material, the titanium oxide is mainly a columnar column of rutile type titanium oxide. It has a gist where it is a crystal. Excellent photocatalytic performance can be obtained by forming columnar crystals of rutyl-type titanium oxide, which was thought to be inferior in photocatalytic activity to anatase-type titanium oxide.

【0017】

Among them, those in which the ratio of crystal grains whose <110> direction is oriented within 45 ° from the perpendicular direction of the film surface is 50% by volume or more with respect to the entire rutile-type titanium oxide columnar crystal is a photocatalyst. Extremely excellent in characteristics. Moreover, it is recommended that the thickness of the photocatalyst film is 0.1 μm or more. Further, a method in which an intermediate layer containing a Ti-containing metal is provided at the interface between the photocatalyst film and the base material is a preferred embodiment of the first invention because the adhesion to the base material is enhanced.

【0018】

In the second invention, which solves the second problem, in a photocatalyst film coating material in which a photocatalyst film containing titanium oxide is laminated on at least one side of a base material, the photocatalyst film laminated surface of the base material is Mn, Zn, This metal consists of a metal containing at least 5 atomic% in total of one or more elements selected from the group consisting of Cr, Fe, Cd, Co, Ni, Sn, Pb, Cu, Ag, Pd, Pt and Au. The gist is that a conductive intermediate layer is formed on the surface, a photocatalyst film is formed on the conductive intermediate layer, and pinholes penetrating from the surface of the photocatalyst film to the metal surface are present.

【0019】

Further, the photocatalyst film coating material according to the second invention is the metal surface of the photocatalyst film coating material and the base material used for the photocatalyst film coating material when the anodic polarization curve is measured under the same conditions. It can also be said that the ratio of the anode current values at a potential that is 500 mV noble than the natural potential satisfies the following equation. 1x10^-7Ai / Ao1 x 10^-1However, Ai: anode current value at the above potential of the photocatalyst film coating material Ao: Anodic current value at the above potential on the metal surface of the base material [0020]

In the second invention, anatase-type titanium oxide may be used as the photocatalyst film, but one made of rutile-type titanium oxide having the same configuration as that of the first invention is preferable because it exhibits higher catalytic performance.

【0021】

The conductive intermediate layer in the second invention preferably has a thickness of 10 nm to 5 μm, and has good adhesion of the photocatalyst film. The conductive intermediate layer may be a Ti-containing metal layer or a layer containing Ti and O and a metal element contained in the metal substrate. In the case of a layer containing Ti, O and a metal element, Ti and O are present in a high concentration on the photocatalyst film side and the metal element is present in a high concentration on the metal substrate side in the thickness direction of the conductive intermediate layer. The inclined composition is particularly preferable for improving the adhesion between the metal base material and the photocatalyst film.

【0022】

In the second invention, one or more elements selected from the group consisting of Mn, Zn, Cr, Fe, Cd, Co, Ni, Sn, Pb, Cu, Ag, Pd, Pt and Au are used as the base material. Laminates having a metal plating layer containing 5 atomic% or more on the surface can be used. Of course, such a metal itself can be used as a base material, and these base materials can also be preferably used in the first invention.

【0023】

The method for producing a photocatalyst film coating material (third invention) according to the first invention, which solves the third problem, has a gist in that the photocatalyst film is formed by arc ion plating targeting a Ti-containing metal cathode.

【0024】

Further, in the method for producing a photocatalyst film coating material (fourth invention) according to the second invention, which solves the fourth problem, a Ti-containing metal is used as a cathode target, and Ti is contained on the metal substrate by arc ion plating in vacuum. After forming a conductive intermediate layer made of metal, arc ion plating is performed as an oxygen-containing gas atmosphere to form a titanium oxide-containing photocatalyst film on the Ti-containing metal layer.

【0025】

The fifth invention of the present application, which solves the fifth problem, decomposes the pollutant by contacting a gas or a liquid containing the pollutant while irradiating the photocatalyst film surface of the photocatalyst film coating material with ultraviolet rays. This is a method for purifying pollutant-containing substances. In particular, a purification method in which the pollutant is volatile and the pollutant in the liquid is moved into the gas and then the pollutant is decomposed is preferably adopted.

【0026】

The sixth invention of the present application, which solves the sixth problem, includes at least a photocatalyst unit provided with the photocatalyst film coating material of the present invention and an ultraviolet irradiation unit that irradiates the photocatalyst film surface of the photocatalyst film coating material of the photocatalyst unit with ultraviolet rays. , A pollutant-containing material purification device including a pollutant-containing material introducing means for guiding a pollutant-containing material to the photocatalyst unit and bringing it into contact with a photocatalyst film surface irradiated with ultraviolet rays.

【0027】

If the pollutant is a malodorous substance and the photocatalyst part is provided with a photocatalyst film coating material or a photocatalyst film coating material and an adsorbent, it becomes a pollutant-containing material purification device useful for garbage disposal and is used in a clean room. When used for air purification, pollutants such as organic gases can be effectively removed.

【0028】

When the pollutant is a volatile pollutant, the gas injection means is further provided with a liquid storage unit for accommodating a liquid containing the volatile pollutant and a gas injection means for injecting gas into the liquid storage unit. It is preferable to use a pollutant-containing purification device configured to guide the pollutant vaporized by injecting a gas into the liquid storage section to the photocatalyst section via the pollutant-containing substance introducing means. ..

【0029】

BEST MODE FOR CARRYING OUT THE INVENTION

First, the photocatalyst film coating material of the first invention of the present application and the production method of the third invention will be described.

【0030】

As described above, according to the conventional method, even if PVD or the like useful as a film forming method is applied, as long as it is a film, an effective reaction surface area comparable to that of titanium oxide powder cannot be obtained, and such titanium oxide cannot be obtained. Even if the anatase-type titanium oxide crystals are oriented to improve the photocatalytic properties of the film, the performance that exceeds the photocatalytic properties of the anatase-type titanium oxide powder cannot be obtained, and in the end, titanium oxide is used in the air and liquid purification process. I had a problem that it could not be applied.

【0031】

In solving the above problem, the present inventors have focused on a rutile-type titanium oxide crystal, which has not been considered until now because it is inferior in photocatalytic properties to anatase-type titanium oxide crystal. As described above, both rutile-type titanium oxide and anatase-type titanium oxide have photocatalytic properties, but it is generally considered that anatase-type titanium oxide has higher photocatalytic properties than rutile-type titanium oxide, and is used for photocatalysts. Most of the titanium oxide powder in the above is anatase-type titanium oxide, and in many cases, the anatase-type titanium oxide is used to form the titanium oxide film. However, with the conventional method, even if the crystal orientation of anatase-type titanium oxide is controlled, the desired photocatalytic property cannot be obtained. Therefore, the present inventors changed the viewpoint, focused on rutile-type titanium oxide, and focused on the crystal thereof. The orientation was changed in various ways, and the relationship with the photocatalytic properties was investigated. As a result, if the rutile-type titanium oxide <110> is oriented perpendicular to the photocatalytic film surface, it is possible to obtain extremely excellent properties that exceed the photocatalytic properties of the anatase-type titanium oxide powder, even though it is a film. The heading and the present invention have been completed.

【0032】

As described above, the coating material of the first invention of the present application is a base material coated with a photocatalyst film (hereinafter, may be simply abbreviated as "film") containing columnar crystals of rutile-type titanium oxide. However, the most important point exists. Among them, the <110> direction of rutile-type titanium oxide is oriented perpendicular to the surface of the photocatalyst film. Specifically, in the columnar crystals of rutile-type titanium oxide, the <110> direction is 45 ° from the perpendicular direction of the surface of the photocatalyst film. Extremely high photocatalytic properties can be obtained if the proportion of crystal grains oriented within (hereinafter, may be abbreviated as <110> oriented crystal grains) is 50% by volume or more. The above <110> direction is a general term for crystallically equivalent directions such as [110], [-110], [1-10], and [-1-10] of rutile type titanium oxide crystals. Means things.

【0033】

The larger the volume ratio of the <110> oriented crystal grains, the better the photocatalytic characteristics. Therefore, it is preferable that the volume ratio is 50% by volume or more. It is more preferably 60% by volume or more, still more preferably 70% by volume or more. The components other than the <110> oriented crystal grains are not particularly limited and are arbitrary, and not only rutile-type titanium oxide crystals that are not oriented in the above-mentioned direction but also anatase-type titanium oxide crystals are included. The presence of components completely different from those of the above may be present, and the presence of these components does not reduce the desired photocatalytic properties. Rather, when the region other than rutile-type titanium oxide is a metal phase such as Ni, Pd, Pt, or a compound phase having a component different from that of titanium oxide; a metal phase such as Ni, Pd, Pt, or titanium oxide on the film surface. When the compound phase of a component different from the above is dispersed as particles, the cathode reaction by the photocatalyst is more likely to occur in the region as compared with the titanium oxide region, and as a result, the site of the anode reaction and the cathode reaction of the photocatalyst is generated. There is an advantage that the photocatalytic properties are often further enhanced because they are separated and the loss due to the cancellation of both reactions is minimized.

【0034】

In the first invention of the present application, the ratio (volume%) of the above <110> oriented crystal grains in the columnar crystal of rutile type titanium oxide is measured by observing the cross section of the film using a transmission electron microscope (TEM). can do. The method will be described below.

【0035】

First, after observing the cross section of the photocatalyst film at a magnification of about 100,000 times, a diffraction spot or diffraction ring corresponding to rutile type titanium oxide is selected from the electron beam diffraction obtained from the entire film, and this diffracted wave is connected. Observe the dark field image obtained by the image. Then, only the rutile-type titanium oxide crystal grains corresponding to the diffracted wave become bright, so that the desired rutile-type titanium oxide can be specified.

【0036】

Next, each of the rutile-type titanium oxide crystal grains identified by the above method was irradiated with a finely squeezed electron beam using FE-TEM (Field Emission TEM). By analyzing the orientation of the diffraction spots obtained from the crystal grains of the above, it is possible to determine which direction the <110> direction of the crystal grains is facing. According to this analysis method, it has an excellent feature that sufficient electron beam brightness can be obtained even if the electron beam is narrowed down to the order of nm.

【0037】

By repeating these operations, the ratio (volume ratio%) of the crystal grains whose <110> direction is oriented within 45 ° from the perpendicular (normal) of the photocatalyst film surface in the columnar crystals of rutile-type titanium oxide. Can be calculated.

【0038】

According to the above method, the relationship between the volume ratio of the <110> oriented crystal grains and the photocatalyst characteristics was examined in detail. When the volume ratio of the crystal grains was small, the photocatalyst characteristics were smaller than those of the anatase-type titanium oxide powder. , It was about the same as rutile type titanium oxide powder, but as the volume ratio increased, the photocatalytic characteristics became higher than that of rutile type titanium oxide powder, and when the volume ratio exceeded 50% by volume, the photocatalyst characteristics increased sharply. However, it was revealed that the characteristics of the anatase-type titanium oxide powder were also exceeded (see the examples described later).

【0039】

When the base material coated with the rutile-type titanium oxide film is plate-like and flat, the rutile-type titanium oxide crystals (110) and (110) obtained by X-ray diffraction using normal θ-2θ diffraction conditions ( When the intensity ratio of the diffraction peak of 101) [hereinafter referred to as "intensity ratio of (110) / (101)" exceeds 3, excellent photocatalytic properties exceeding those of anatase-type titanium oxide powder can be obtained. As the intensity ratio increases, the photocatalytic properties are further improved. It is more preferably more than 4, and even more preferably more than 5.

【0040】

However, from the viewpoint of increasing the effective surface area of the photocatalytic reaction and obtaining a high degree of photocatalyst characteristics, the shape of the base material is preferably a complex uneven surface such as a mesh or a linear shape. In the case of having a complicated shape, even if the <110> direction of the rutile type crystal in the film is microscopically oriented perpendicular to the film surface, the crystal orientation varies macroscopically. It is difficult to determine the intensity ratio of (110) / (101) by X-ray diffractometry.

【0041】

Therefore, unless the base material is a perfect flat surface, the intensity ratio cannot be determined by X-ray diffraction, and the above-mentioned X-ray diffraction method cannot be applied to an actual coating material having a complicated shape. Therefore, in such a case, as described above, based on the microscopic information obtained by TEM cross-sectional observation, the structure in which the <110> direction of the rutile type titanium oxide is oriented perpendicular to the surface of the photocatalyst film is specified. It will be.

【0042】

The reason why excellent photocatalytic properties can be obtained by using a rutile-type titanium oxide film controlled to a predetermined crystal orientation is unknown in detail, but it is considered as follows. As described above, when the volume ratio of the <110> oriented crystal grains of rutile type titanium oxide is less than 50%, the orientation of the crystal grains becomes close to a random state, and as a result, the obtained photocatalytic properties are anatase type titanium oxide powder. Will be lower than. Band Theoretically, both anatase-type titanium oxide and rutel-type titanium oxide have the same band gap as any crystal, but rutile-type titanium oxide conducts more than anatase-type titanium oxide. It is thought that the photocatalytic properties of rutile-type titanium oxide powder are lower than those of anatase-type titanium oxide powder because the level of the band is slightly lower and the reduction reaction is less likely to occur (CMC "Photoclean Revolution", p116-p118). However, this alone cannot fully explain the difference in characteristics between the two, why the oriented rutel-type titanium oxide film is used to further enhance the photocatalytic properties as compared with the anatase-type titanium oxide.

【0043】

Therefore, inferring the cause from the background of reaching the first invention of the present application, the anatase-type titanium oxide crystal exhibits the same photocatalytic properties with respect to ultraviolet rays incident from all directions, whereas the rutile-type titanium oxide crystal. The photocatalyst characteristics of the above are highly orientation-dependent with respect to the incident ultraviolet rays, and when ultraviolet rays are incident from the <110> direction, they exhibit stronger photocatalytic characteristics than anatase-type titanium oxide crystals, and when irradiated with ultraviolet rays from other directions. It is considered that the photocatalyst characteristics may be significantly reduced. As a result, in the powder state or the random crystal orientation state, the anatase-type titanium oxide crystal having no orientation dependence exhibits superior photocatalytic properties, whereas the rutile-type titanium oxide crystal exhibits ultraviolet rays in the <110> direction. Since only the crystal grains that are oriented in the direction exhibit the photocatalyst characteristics, it is considered that the overall photocatalyst characteristics are deteriorated. On the other hand, when the <110> direction of the rutile type titanium oxide crystal is oriented perpendicular to the surface of the photocatalyst film and the ultraviolet irradiation direction and the <110> direction coincide with each other as in the first invention of the present application, the case is compared with the anatase type titanium oxide. It is presumed that extremely excellent photocatalyst characteristics are exhibited.

【0044】

In the first invention of the present application, the thickness of the rutile type titanium oxide film is preferably 0.1 μm or more. When the film thickness is 0.1 μm or more, the photocatalyst characteristics begin to improve. It is more preferably 0.5 μm or more, and even more preferably 1 μm or more.

【0045】

If the thickness exceeds 1 μm, the effect of increasing the photocatalyst characteristics due to the increase in the film thickness is saturated, and problems such as cost increase and decrease in adhesion due to long-term treatment for thickening the film occur. Considering these circumstances, it is recommended to control the film thickness to 20 μm or less, more preferably 10 μm or less, and even more preferably 5 μm or less.

【0046】

The photocatalyst film coating material of the first invention of the present application may be composed of a single layer type in which the titanium oxide film is directly coated on the surface of the base material, but for the purpose of improving the adhesion between the photocatalyst film and the base material. It is recommended to use a multi-layer type in which an intermediate layer containing a Ti-containing metal is provided at the interface, and such an embodiment is also included in the scope of the first invention of the present application.

【0047】

The intermediate layer may contain at least Ti, which is the same metal as titanium oxide as a photocatalyst, may contain Ti metal alone, or may contain other metals other than Ti. Is also good. In particular, it is preferable to adopt the structure of the Ti-containing metal layer in the second invention described later.

【0048】

In order to obtain the desired adhesion, the thickness of the intermediate layer is preferably 10 to 500 nm. By controlling the thickness within such a range, the interfacial strain caused by the difference in mechanical properties between the film and the base material can be alleviated by the plastic deformation of the metal layer which is the intermediate layer. In order to obtain even better adhesion, it is recommended that the thickness of the intermediate layer be 10 nm or more, more preferably 15 nm or more, and even more preferably 20 nm or more. However, if the intermediate layer becomes too thick, the titanium oxide film is likely to crack due to plastic deformation of the soft metallic titanium layer, so the film thickness is 500 nm or less, more preferably 450 nm or less, and even more preferably 400 nm or less. It is recommended to control to.

【0049】

The thickness of the titanium oxide film and the thickness of the intermediate layer can be easily measured by the cross-sectional observation method of the transmission electron microscope (TEM) described above.

【0050】

The photocatalyst film coating material of the first invention of the present application has the most important point where the crystal structure of the photocatalyst film is specified, and the type of the base material on which the photocatalyst film is formed is not particularly limited. For example, metals such as iron, titanium, aluminum and copper and their alloys; silicon wafers; and further resin, glass, ceramics and the like can be used. The most preferable is the base material preferably used in the second invention described later.

【0051】

Next, a method for producing the coating material of the first invention of the present application (third invention) will be described.

【0052】

In order to form a photocatalyst film in which the <110> direction of rutile-type titanium oxide is controlled to be oriented perpendicular to the film surface as in the first invention of the present application, a general method (binder) currently widely used is used. It is difficult to use the method or the method of applying and firing an organic titanium compound solution), and it is necessary to apply the vapor phase coating method of PVD or CVD, which makes it easy to control the crystal structure. That is, physical vapor deposition (PVD) such as vapor deposition, sputtering, holocathode ion plating, arc ion plating; or chemical vapor deposition (CVD) using hot filaments or ECR plasma is used. A desired film can be formed by appropriately controlling the film conditions.

【0053】

On the other hand, when an attempt is made to fix the titanium oxide powder with, for example, a silicone-based binder, the orientation of the powder is random, so that the crystal orientation is also completely random. In addition, it has been confirmed by TEM observation that the crystal orientation of the obtained titanium oxide photocatalyst film becomes completely random when the method of applying and firing the organic titanium compound solution is used. In the case of the second invention of the present application, titanium oxide showing such a random crystal orientation can also be used.

【0054】

In order to form a desired film, it is preferable to adopt an arc ion plating method in which an arc discharge is generated by targeting a Ti-containing metal cathode. In particular, the atmosphere of the treatment chamber is an oxygen partial pressure of 798 mPa or more and a total pressure of 133 ×. It is preferable that the temperature is 102 mPa or less and the substrate temperature is controlled to 200 ° C or more. The desired photocatalyst film can be easily obtained.

【0055】

First, the atmosphere of the treatment chamber is preferably an oxygen partial pressure of 798 mPa or more. This is because the higher the oxygen partial pressure, the stronger the tendency of the rutile type titanium oxide in the <110> direction to be oriented perpendicular to the photocatalyst surface, and accordingly, the photocatalyst characteristics also improve. It is more preferably 1064 mPa or more, and even more preferably 133 × 10 mPa or more.

【0056】

In addition to oxygen, an inert gas such as argon may be mixed in the treatment atmosphere. However, mixing a reactive gas such as nitrogen is not preferable because impurities are mixed in the titanium oxide. In the first invention of the present application, the total pressure of the treatment atmosphere in which oxygen and, if necessary, an inert gas are mixed, is preferably 133 × 102 mPa or less. If the total pressure exceeds 133 × 102 mPa, arc discharge does not occur and film formation cannot be performed. Therefore, in the first invention of the present application, it is recommended that the upper limit of the oxygen partial pressure is 133 × 102 mPa even in an atmosphere of 100% oxygen.

【0057】

Further, the substrate temperature is preferably 200 ° C. or higher. This is because as the substrate temperature rises, the <110> direction of the rutile-type titanium oxide tends to be oriented perpendicular to the surface of the photocatalyst film, and the photocatalyst characteristics also improve accordingly, more preferably at 300 ° C. or higher. Even more preferably, it is 400 ° C. or higher. From the viewpoint of improving photocatalyst characteristics, the upper limit of the base material temperature is not particularly limited, but considering the energy saving of equipment operation and the heat resistance of the base material, the base material temperature is set to 1000 ° C or less, more preferably 900 ° C. Hereinafter, it is recommended to control the temperature to 800 ° C. or lower, even more preferably.

【0058】

When an intermediate layer is provided between the base material and the photocatalyst film, the surface of the base material is preferably placed in a vacuum on the order of 133 × 10-5 Pa (10-5 Torr) before the titanium oxide film is formed. Bomberd (irradiation with metal ions constituting the Ti-containing metal target and unavoidable residual gas ions) may be performed to control the film thickness to an appropriate level.

【0059】

Next, the photocatalyst film coating material and the method for producing the same (fourth invention) according to the second invention of the present application will be described.

【0060】

As a result of investigating the above-mentioned problem of recombination of electrons and holes, the present inventors have shown in FIG. 1 (a) by adhering a reduction reaction promoting metal on a titanium oxide film to form a reduction reaction site. Instead of preventing such recombination of electrons and holes, the reduction reaction promoting metal is applied to the metal base material itself or the metal layer on the base material surface (the surface on which the photocatalyst film is laminated) (hereinafter, the case of the metal base material itself). And when a metal layer is provided on the surface of an arbitrary base material, both metal parts are collectively represented by "metal surface"), and these metal surfaces are used to form a reduction reaction site. I thought. In order to make the metal surface itself a reduction reaction site, it is necessary to have an exposed metal surface for contact with the object to be treated by photocatalysis, instead of completely covering the metal surface with a photocatalytic film. (Fig. 2 (a), (b)). According to this, the reduction reaction occurs in the exposed metal surface and the electrons in the titanium oxide film move, so that the electrons can be localized. However, for example, a method of forming a titanium oxide film on a metal surface and then grooving is complicated, and even if the titanium oxide film having poor adhesion to the metal surface is formed, a step of grooving or the like is performed. It is not practical because it peels off from the base material inside.

【0061】

For the purpose of improving the adhesion between the titanium oxide film and the metal surface, for example, it is conceivable to provide an intermediate layer made of an organic resin, an inorganic substance, etc. (Fig. 2 (c)), but electron transfer in the insulating intermediate layer. Is hindered and the desired charge separation cannot be performed. Also, when the titanium oxide powder is fixed with a binder or the like, the movement of electrons is hindered by the binder, so that the desired charge separation cannot be performed.

【0062】

Therefore, in the second invention of the present application, a configuration is adopted in which a conductive intermediate layer, which is an intermediate layer that can improve the adhesion between the titanium oxide film and the metal surface and does not hinder the movement of electrons, is provided (Fig. 3). Then, by using pinholes formed in the titanium oxide film or the conductive intermediate layer to form the exposed portion of the metal surface and using the bottom of the pinhole as a reduction reaction site, a complicated process such as grooving is performed. At least, the localization of electrons could be achieved. Since this reduction reaction site does not drop off, it has become possible to exert a high photocatalytic ability for a long period of time. Although FIGS. 2 to 3 show examples of a metal base material, the principle of electron localization is of course the same even when a metal layer is provided on the surface of an arbitrary base material.

【0063】

The photocatalyst film coating material according to the second invention of the present application is a metal base material, a conductive intermediate layer, a photocatalyst film laminated in this order, or a conductive intermediate layer provided with a metal layer on the surface of an arbitrary base material. It is provided with a photocatalyst film. Each layer and the photocatalyst film may be laminated on both sides of each base material.

【0064】

The metal surface (metal substrate or surface metal layer) is one or more selected from the group consisting of Mn, Zn, Cr, Fe, Cd, Co, Ni, Sn, Pb, Cu, Ag, Pd, Pt and Au. Must contain a total of 5 atomic% or more of the above elements. This is because if it is less than 5 atomic%, a reduction reaction site effective for electron localization is not formed. The total concentration of the elements is preferably 10 atomic% or more, more preferably 20 atomic% or more. When the content of any element is 50 atomic% or more, the photocatalyst characteristics tend to be saturated and stabilized, so the upper limit is not particularly specified.

【0065】

All of these metal elements are noble metals than Al. The effect of improving the photocatalytic ability by adding Al was not observed, and Al is outside the scope of the present invention. All of the above elements can be used alone or in admixture of two or more. Of these, Cr and Pt are most preferable because they have a high effect of improving photocatalytic properties, but from an economical point of view, the use of Cr is recommended over expensive Pt.

【0066】

When a metal is used as the base material, the metal containing the above-mentioned reduction reaction promoting metal element as an alloy addition component can be used as it is as the metal base material. Further, a metal film containing these elements is formed on some base material by plating or the like, and then only the base material is removed to form only the metal film, which can also be used as the metal base material. A metal layer (surface metal layer) containing these elements may be formed on the outermost surface layer of the metal plate not containing these elements by means such as plating (including vapor phase coating). Further, a material other than the metal plate, for example, a material in which a metal layer containing these elements is formed on the surface of ceramics, glass, plastic or the like by wet plating or vapor phase plating can also be used. A known method can be adopted as the plating method.

【0067】

Common metal substrates include ordinary steel and stainless steel, but stainless steel is desirable because it contains Cr, which has a high effect of improving photocatalytic properties, and has excellent corrosion resistance. The shape of the base material is not limited to the plate shape, and a network-like body (two-dimensional or three-dimensional), a porous plate having regular or irregular pores, a rod shape, or the like can be appropriately used. Is.

【0068】

A conductive intermediate layer is provided on the metal surface. This layer is not particularly limited as long as it has conductivity and can improve the adhesion between the photocatalyst film (titanium oxide layer) and the metal substrate. The conductive intermediate layer is preferably a metal or a conductor having an electrical resistance equivalent to that of the metal, whereby the photocatalytically excited electrons easily move to the reduction reaction site on the metal surface. can do. It is preferable that the resistance of the intermediate layer is as low as possible so that the excited electrons can move freely. Specifically, it is preferably 500 μΩ · cm or less at 20 ° C., more preferably 200 μΩ · cm or less, and most preferably 100 Ω · cm or less.

【0069】

In the second invention of the present application, two patterns of a Ti-containing metal layer and a layer having Ti and O and a metal contained in the metal base material or the surface metal layer are preferable as the conductive intermediate layer. In the case of the Ti-containing metal layer, the presence of metallic titanium is necessary for improving the adhesion between the photocatalyst film and the metal surface, but a mixed layer of Ti and other metals can also be used. As the other metal, one or more elements selected from the group consisting of Mn, Zn, Cr, Fe, Cd, Co, Ni, Sn, Pb, Cu, Ag, Pd, Pt and Au can be used. .. The most preferable Ti-containing metal layer is a metallic titanium layer substantially composed of metallic titanium only. Even if an unavoidable impurity such as a non-metal is mixed in the metallic titanium layer or the Ti-containing metal layer mixed with other metals, it is included in the second invention of the present application. This is because the object of the second invention can be achieved if the movement of excited electrons is not hindered. The Ti-containing metal layer can be formed by the arc ion plating method, and the pinholes required in the present invention are also formed at the same time as the film formation.

【0070】

FIG. 4 shows the present invention in which a metal titanium layer was formed on stainless steel (SUS304) by an arc ion plating method, and then a photocatalyst film (a columnar crystal layer of rutile-type titanium oxide) having the constitution of the first invention was formed. A transmission electron micrograph of a cross section of a photocatalyst film coating material is shown. In order to grasp the thickness of the metallic titanium layer, there is a method of analyzing the composition of the surface of the photocatalyst film coating material by argon etching by Auger electron spectroscopic analysis. Further, in the case of a photocatalyst film coating material using a net-like material or a non-smooth base material having severe irregularities as the metal base material, it may be difficult to perform Auger electron spectroscopic analysis. , It is advisable to cut out a minute part and observe the cross section with a transmission electron microscope (TEM). The crystal structure of titanium oxide can be grasped by electron diffraction, and the compositions of the base material, the conductive intermediate layer, and the photocatalyst film can be obtained by the energy dispersive X-ray spectrometer (EDX). In addition, the thickness of the intermediate layer can also be obtained from the composition analysis. For convenience, the Ti-containing metal intermediate layer has O at the interface with the photocatalyst film from the place where Ti is 10 atomic% at the interface with the metal substrate. The thickness is determined by using the intermediate layer up to the point where is 10 atomic%. A convergent electron beam grinder (FIB) may be used to prepare a sample for TEM cross-section observation.

【0071】

On the other hand, the layers containing Ti and O and the metal element contained in the metal surface are titanium alkoxides such as titanium tetraethoxydo, titanium tetraisopropoxide, and titanium tetrabutoxide; Ti such as tetraacetylacetonate titanium; It is a layer obtained by applying the contained organic compound on a metal surface and then firing it. When the Ti-containing organic compound is fired, Ti, O, and C remain, and a diffusion phenomenon of metal elements occurs from the metal base material or the surface metal layer during firing. It is a layer having a mixed composition of titanium oxide, C, and a diffused metal element. In the generated conductive intermediate layer, a high concentration of diffusing elements is present on the metal surface side, and there are few diffusing metal elements on the opposite surface side of the metal surface on which the photocatalyst film is formed later. It is a layer with a gradient composition in which Ti and O are present in high concentrations.

【0072】

The structure of the above-mentioned type of conductive intermediate layer can be easily obtained by analyzing the composition using Auger electron spectroscopy (AES) while performing argon sputtering etching from the photocatalyst film side to the metal substrate side. Although it can be confirmed, when the metal base material has a complicated shape, the above-mentioned TEM cross-sectional observation method may be adopted. Figure 5 shows the conductivity formed after using stainless steel SUS304 (containing Fe, Cr, Ni) as a metal base material, applying an organic solvent solution containing tetraacetylacetonate titanium, and firing at 500 ° C. The AES profile of the sex intermediate layer and the stainless steel is shown. The depth (μm) on the horizontal axis is calculated from the argon sputtering etching rate. It can be seen that Ti, O, C, Fe, Ni and Cr are detected, Ti, O and C gradually decrease from the vicinity of the surface, and conversely Fe, Ni and Cr gradually increase.

【0073】

In the case of the inclined composition in the second invention of the present application, the conductive intermediate layer contains 10 atomic% of the most abundant metal element among the metal elements contained in the base material, and thus Ti, O, The amount of the most abundant element in C is up to 10 atomic%. In FIG. 5, the intermediate layer starts from the place where Fe is 10 atomic%, and the intermediate layer is from the place where O is 10 atomic%, and the thickness is 0.2 μm. .. The portion where Fe is 10 atomic% or less (on the left side of the Fe 10 atomic% line) is a titanium oxide layer, which can be equated with a photocatalyst film.

【0074】

By forming the conductive intermediate layer having such an inclined composition, the structure is close to that of the metal surface on the metal surface side, and the structure is almost the same as that of titanium oxide on the photocatalyst film side, so that the adhesion between them is improved. It is. After forming the conductive intermediate layer having such a gradient composition, the Ti-containing organic compound exemplified above (the same compound as that used for forming the conductive intermediate layer or another kind of compound may be used) is further added. The photocatalyst film can be laminated by coating and firing. The film obtained through the second coating / firing step of the Ti-containing organic compound is a titanium oxide layer having excellent photocatalytic activity without mixing of metal elements. This is because the titanium oxide layer on the outermost surface of the conductive intermediate layer reliably prevents the diffusion of metal elements from the metal surface.

【0075】

In both the Ti-containing metal layer and the layer having the above-mentioned inclined composition, the thickness of the intermediate layer is preferably 10 nm to 5 μm. When it is thinner than 10 nm, the effect of improving the adhesion between the metal substrate and the photocatalyst film is not exhibited. 20 nm or more is preferable, and 30 nm or more is more preferable. However, if the intermediate layer becomes too thick beyond 5 μm, the distance that the electrons excited by the photocatalyst film should move, that is, the distance to the reduction reaction site on the metal substrate becomes long, and the effect of improving the photocatalytic properties is improved. It is difficult to obtain and is not preferable. A more preferable upper limit of the thickness of the intermediate layer is 3 μm, more preferably 1 μm.

【0076】

When the interface between the photocatalyst film and the conductive intermediate layer or the interface between the conductive intermediate layer and the metal surface is observed with a microscopic field on the order of nm using TEM, the resistance is 500 μΩ · cm (20). Inevitable impurity layer with insulation exceeding ° C) (for example, composed of iron oxide formed by oxidation of stainless steel base material during firing) may be locally present, but it is excited by photocatalytic reaction. Since the object of the present invention can be achieved if the generated electrons can reach the reduction reaction site at the bottom of the pinhole, even if such an impurity layer is partially present, it is included in the present invention.

【0077】

A photocatalytic film is formed on the conductive intermediate layer. As the photocatalyst film in the second invention, iron oxide, tungsten oxide, silicon oxide and the like can be used in addition to titanium oxide. From the viewpoint of photocatalytic ability, a photocatalytic membrane made of only titanium oxide is most preferable. As the titanium oxide, anatase type can also be used, but the specific rutile type described in the first invention is more preferable. In particular, the titanium oxide layer formed by the arc ion plating method shown in FIG. 4 is excellent because it is a rutile type crystal described in the first invention and shows a structure in which the <110> direction is oriented vertically (to the base material). It is suitable because it exhibits photocatalytic properties.

【0078】

In order to localize the excited electrons formed in the photocatalyst film to the reduction reaction site, an exposed part where the metal surface can come into contact with the object to be treated is required, and the reduction reaction is performed in this part as described above. Localization of excitation electrons can be achieved by the presence of the facilitating metal. By the present inventors, and an arc ion plating method, by the application and firing of Ti-containing organic compound if there is a photocatalyst film and the conductive intermediate layer formed me, it was confirmed that improvement of the photocatalytic ability is observed However, the reason for this is that these film forming methods generate an appropriate amount of pinholes penetrating from the surface of the photocatalyst film to the surface of the metal substrate in the photocatalyst film and the conductive intermediate layer, and the electron localization effect is exhibited. It is thought that this is because it is being demonstrated. When the presence of pinholes was confirmed electrochemically, the photocatalyst film coating material of the second invention of the present application in which a photocatalyst film and a conductive intermediate layer were laminated on a metal substrate was a titanium oxide film having almost no pinholes (for example, by sputtering). It showed a higher anode current than the one coated with a metal substrate by (formed). This confirmed the existence of pinholes and the presence of exposed metal surfaces.

【0079】

Against this background, regarding the second invention of the present application, claim 3 defines a photocatalyst film coating material in which the presence of pinholes is essential, and claim 4 defines a photocatalyst film coating material, even if the pinholes cannot be visually confirmed. Since the one showing a certain amount of anode current value contributes to the above electron localization, the photocatalyst film coating material that requires the requirement of the anode current value is defined. The configuration of the present invention in which a conductive intermediate layer is provided to promote electron localization can also be applied to a general industrial catalyst whose characteristics are improved by supporting a metal, and an improvement in catalytic ability and a long life are achieved. Will be done.

【0080】

The thickness of the photocatalyst film is preferably 0.05 μm or more in order to exert the electron localization effect. It is more preferably 0.1 μm or more, still more preferably 0.2 μm or more. The photocatalytic ability increases as the film thickness increases, but if it becomes too thick, the number of pinholes penetrating from the photocatalytic film surface to the metal surface may decrease, and the electron localization effect may deteriorate. On top of that, the photocatalyst film itself is easily peeled off, so it is preferably 10 μm or less. It is more preferably 5 μm or less, still more preferably 3 μm or less.

【0081】

In the exposed metal surface at the bottom of the pinhole, a reduction reaction is more likely to occur than in the vicinity of the surface of the titanium oxide film, and the metal surface comes into contact with the object to be treated to cause a reduction reaction, which consumes electrons. The electrons excited by are moving. Then, in the vicinity of the surface of the photocatalyst film, the holes generated as a result of the photocatalytic action are not consumed by recombination with electrons or the like, and the oxidative decomposition reaction of the object to be treated is carried out. Therefore, the photocatalyst characteristics are excellent, and this high performance can be maintained for a long period of time.

【0082】

In the second invention of the present application, if a reduction reaction site that contributes to such electron localization is generated on the metal surface, the object is achieved. Therefore, a layer by coating / firing an arc ion plating or a Ti-containing organic compound. Anything that has a pinhole or satisfies the specified requirement of the anode current is included in the second invention of the present application. It should be noted that the sputtering film formed under normal conditions has almost no or few pinholes and does not satisfy the specified requirements for the anode current, so it is not very preferable. Those that satisfy the specified requirements for the anode current by intentionally introducing pinholes can be used in the second invention of the present application.

【0083】

The stipulated requirement for the anode current is that when the anode polarization curve is measured under the same conditions for the photocatalyst film coating material and the metal surface of the base material used for the photocatalyst film coating material, the natural potential of the metal surface is 500 mV. The ratio of the anode current values to the noble potential satisfies the following equation. 1x10^-7Ai / Ao1 x 10^-1However, Ai: anode current value at the above potential of the photocatalyst film coating material Ao: Anodic current value at the above potential on the metal surface of the base material [0084]

When the anodic polarization measurement is performed in an acidic aqueous solution in which the metal base material or the surface metal layer is dissolved and titanium oxide is not dissolved, an anode current flows as much as possible as compared with the test piece completely covered with titanium oxide. In this case, it is considered that the pinhole is present in the titanium oxide film because it indicates that the metal element in the metal surface is eluted in the test solution through the pinhole of the titanium oxide film.

【0085】

Since the anode current can be measured under various conditions, the anode current value Ao with the metal surface as it is and the anode current value Ai after laminating the conductive intermediate layer and the photocatalyst film when measured under the same conditions The ratio is specified. The larger the ratio, the higher the pinhole density, and the smaller the ratio, the lower the pinhole density. In the present invention, in accordance with JIS G0579, a saturated caromel electrode is used as a collation electrode, and the test area is 1 cm in a 1 mol / liter sulfuric acid aqueous solution at room temperature.²The test was performed using a test agent in which the surroundings were masked so as to be.

【0086】

Ai / Ao is 1x10^-7If it is smaller than, the number of pinholes is too small, the number of reduction reaction sites described above is small, and the electron localization effect cannot be sufficiently exerted, which is not preferable. Ai / Ao is 1x10^-1If it is larger than, the pinhole density is too high, the area ratio of the working surface of the photocatalyst film is small, and the photocatalyst characteristics are inferior, which is not preferable. A more preferred range is 1x10^-6~1×10^-2, A more preferred range is 1x10^-5~1×10^-3Is.

【0087】

Hereinafter, a preferred method for producing the photocatalyst film coating material according to the second invention of the present application will be described. As long as it achieves the object of the second invention of the present application (satisfies the provisions of claims 3 and 4), it is not limited to the one obtained by the following production method, and is included in the second invention of the present application.

【0088】

First, the first method is a method using arc ion plating as in the first (3) invention (fourth invention). This manufacturing method is a simple method for manufacturing a photocatalyst film coating material provided with a conductive intermediate layer made of a Ti-containing metal layer. Specifically, a Ti-containing metal is used as the cathode target, a negative bias is applied to the metal base material, an arc discharge is generated in vacuum to form a Ti-containing metal layer on the surface of the metal base material, and then. By introducing an oxygen-containing gas to generate an arc discharge, a titanium oxide film can be formed on the surface of the Ti-containing metal layer. Further, if the same conditions as those of the third invention described above are adopted, a rutile-type titanium oxide film having a specific structure having excellent photocatalytic activity can be formed, which is the most preferable aspect of the present invention.

【0089】

The photocatalyst film coating material according to the second invention can also be produced by a method of firing a Ti-containing organic compound. This is a simple method for producing a photocatalyst film coating material having a conductive intermediate layer having the above-mentioned inclined composition. Examples of the Ti-containing organic compound include titanium alkoxides such as titanium tetraethoxydo, titanium tetraisopropoxide, and titanium tetrabutoxide, and tetraacetylacetonate titanium. If necessary, these are dissolved in an organic solvent such as alcohol or an aliphatic / aromatic hydrocarbon, applied on a metal surface, and then fired to form a conductive intermediate layer having a gradient composition as described above. Then, a titanium oxide film (photocatalyst film) can be formed by further coating and firing a Ti-containing organic compound of the same type or different type as the intermediate layer compound on the conductive intermediate layer. The titanium oxide film obtained by this method has a random anatase type, but in the case of the second invention, an anatase type may be adopted.

【0090】

In order to form pinholes in the photocatalyst film and the conductive intermediate layer by the above two methods and to make the above preferable range of the anode current value ratio, the average roughness Ra of the center line of the metal surface should be 0.02 to 2 μm. Is preferable. When the photocatalyst film and the conductive intermediate layer are formed by another method, pinholes may be formed by appropriately setting the film forming conditions and the like.

【0091】

Next, a purification method (fifth invention) and a purification device (sixth invention) using the photocatalyst film coating material according to the first and second inventions described so far will be described.

【0092】

The fifth invention is characterized in that the pollutant-containing substance is decomposed by contacting a gas or liquid containing the pollutant while irradiating the photocatalyst film surface of the photocatalyst film coating material with ultraviolet rays. It is a purification method. Since the photocatalyst film coating material of the present invention has excellent adhesion to the base material, it can be brought into contact with not only a gas but also a liquid to decompose pollutants. By irradiating with ultraviolet rays, pollutants can be quickly decomposed, which is also practical in terms of durability.

【0093】

The compound to be decomposed is not particularly limited, but as pollutants in the gas (atmosphere), ammonia generated from garbage, malodorous substances such as methyl mercaptan and hydrogen sulfide, airborne bacteria, NOx (nitrogen oxide) and the like. Examples include air pollutants such as SOx (sulfur oxide). Examples of the organic gas generated in a clean room or the like include aromatic esters such as phthalates, aliphatic esters, toluene, ethylbenzene and the like. Examples of pollutants in the liquid (in water) include microorganisms such as algae, carcasses of plankton, ammonia, dioxin and the like. Further, from the viewpoint of volatile pollutants, highly volatile organic solvents such as trichloroethylene and tetrochloroethylene may be mixed in water, and the photocatalyst film coating material of the present invention is also effective for their decomposition.

【0094】

When the pollutant is volatile and contained in the liquid, it is preferable to move the pollutant in the liquid into the gas and then decompose the pollutant by photocatalytic action.

【0095】

The apparatus for carrying out the above decomposition / purification method (sixth invention) irradiates at least the photocatalyst section provided with the photocatalyst film coating material according to the present invention and the photocatalyst film surface of the photocatalyst film coating material of the photocatalyst section with ultraviolet rays. It is provided with an ultraviolet irradiation unit and a contaminant-containing material introducing means for guiding a pollutant-containing substance to the photocatalyst unit and bringing it into contact with a photocatalyst film surface irradiated with ultraviolet rays.

【0096】

When the pollutant is a malodorous substance, it is preferable to dispose not only the photocatalyst film coating material of the present invention but also an adsorbent such as activated charcoal or zeolite in the photocatalyst portion. In this case, the malodorous substance generated from garbage. It is suitable as a processing device for. A specific example is shown in FIG. FIG. 6-17 is a food waste treatment tank (conposter) for reducing the amount of food waste having a rectangular cross section and a square shape by bacteria to compost, and the purification device 10 of the present invention is installed above the food waste treatment tank 17. Has been done.

【0097】

11 is a deodorizing tank arranged above the square-shaped kitchen waste treatment tank 17, 15 is a processing gas introduction pipe that connects the kitchen waste treatment tank 17 and the deodorizing tank 11, and 16 is a deodorizing tank. The treated gas discharge pipe and 14 that communicate the 11 and the kitchen waste treatment tank 17 are suction fans provided in the treated gas introduction pipe. A photocatalyst film coating material 12 is attached to the inner peripheral surface of the deodorant tank 11 over the entire circumference. Further, inside the deodorizing tank 11, a fluorescent lamp type ultraviolet lamp 13 (a sterilizing lamp having a wavelength of 250 nm or the like can be used) extending along the central axis of the deodorizing tank 11 is arranged.

【0098】

Therefore, the deodorizing device 10 as a contaminant-containing purification device is provided on the surfaces of the deodorizing tank 11 as a photocatalyst unit including the photocatalyst film coating material 12 and the photocatalyst film coating material 12 arranged in the deodorizing tank 11. An ultraviolet lamp 13 as an ultraviolet irradiation part for irradiating ultraviolet rays and a gas containing a malodorous substance which is a pollutant are guided to a deodorizing tank 11 and brought into contact with the surface of a photocatalyst film coating material 12 irradiated with ultraviolet rays. It is composed of a suction fan 14 as a means for introducing a pollutant-containing substance, a treated gas introduction pipe 15, and a treated gas discharge pipe 16.

【0099】

In the kitchen waste processing tank 17 provided with the deodorizing device 10 configured in this way, the kitchen waste processing tank 17 contains food waste consisting of leftover food, vegetable waste, meat, etc., and yeast for promoting fermentation by bacteria. When bacteria are added and the kitchen waste is fermented, a gas containing malodorous substances and bacteria at a temperature of about 45 ° C is generated in the kitchen waste treatment tank 17. This bacterium is a bacterium such as a thermophilic bacterium that accompanies composting of garbage. The gas containing the malodorous substance and bacteria is guided from the garbage treatment tank 17 into the deodorization tank 11 via the treatment gas introduction pipe 15, and the surface of the photocatalyst film coating material 12 is irradiated with ultraviolet rays by the ultraviolet lamp 13. At the same time, if the gas is brought into contact with the photocatalyst film by passing through the deodorizing tank 11, the malodorous substance is decomposed and the bacteria are sterilized. Then, the gas that has passed through the deodorant tank 11 returns to the kitchen waste treatment tank 17 via the treatment gas discharge pipe 16.

【0100】

In the deodorizing tank 11, the photocatalyst film coating material 12 may be cooled to, for example, about 5 ° C. by providing a cooling coil and flowing a cooling medium through the cooling coil. As a result, moisture in the gas comes into contact with the photocatalyst film coating material 12 and condenses, so that malodorous substances and bacteria can easily come into contact with the surface of the photocatalyst film coating material 12. Further, the deodorizing tank 11 may be provided with an adsorbent containing zeolite or activated charcoal. Alternatively, the surface of the photocatalyst film coating material 12 may have a structure in which particles of an adsorbent having an malodor adsorbing function such as activated charcoal or zeolite are dispersed, and a composite of the photocatalyst and the adsorbent may be used. .. It is more effective in removing bad odors.

【0101】

Further, the purification device according to the sixth invention of the present application can also be used for purifying air in a clean room room or a local space in a clean room, that is, for decomposing and removing organic gas. When the organic gas generated in the clean room adheres to the surface of the silicon wafer, for example, the surface of the silicon wafer becomes hydrophobic and the adhesive force of the film to be formed later becomes weak, so the organic gas is decomposed. Need to be removed. A specific example of the air purification device is shown in FIG.

【0102】

25 in FIG. 7 is a wafer storage box for storing a large number of silicon wafers 26 inside. The wafer storage box 25 is installed in a clean room of about 100,000 class and forms a local space in the clean room. However, when the silicon wafer 26 is carried in and out, air containing pollutants invades. A quartz glass window 24 that allows ultraviolet rays to pass through is provided on the back surface of the wafer storage box 25, and the photocatalyst panel 21 is arranged at a position close to the quartz glass window 24 in the wafer storage box 25. The photocatalyst panel 21 is configured by attaching the photocatalyst film coating material 22 on a rectangular panel substrate. Further, a fluorescent lamp type ultraviolet lamp 23 is arranged on the outside of the wafer storage box 25 with the quartz glass window 24 in between. Inside the wafer storage box 25, a sample table 27 is arranged at a position opposite to the quartz glass window 24 with the photocatalyst panel 21 in between, and the silicon wafer 26 is placed on the sample table 27. ing. The ultraviolet lamp 23 irradiates the surface of the photocatalyst film coating material 22 with ultraviolet rays through the quartz glass window 24, and has a function of fluidizing the air in the wafer storage box 25 due to the temperature difference caused by the lamp heat. As shown by the arrow in FIG. 7, the ultraviolet lamp 23 can circulate the air in the wafer storage box 25 so as to come into contact with the surface of the photocatalyst film coating material 22.

【0103】

The air purification device 20 as a pollutant-containing substance purification device emits ultraviolet rays to the surfaces of the photocatalyst panel 21 as a photocatalyst unit formed by using the photocatalyst film coating material 22 and the photocatalyst film coating material 22 constituting the photocatalyst panel 21. It is composed of an ultraviolet lamp 23 and a quartz glass window 24 as an ultraviolet irradiation unit to be irradiated. In this example, the ultraviolet lamp 23 introduces a pollutant-containing substance for guiding a gas containing an organic gas, which is a pollutant, to the photocatalyst panel 21 and bringing it into contact with the surface of the photocatalyst film coating material 22 irradiated with ultraviolet rays. It also functions as a means.

【0104】

The purification device according to the sixth invention of the present application can also be applied to the decomposition / removal of malodorous substances in water. For example, when raising ornamental fish, ammonia is generated and dissolved in water, and Fig. 8 shows a specific example that can be used to decompose and remove such malodorous substances.

【0105】

FIG. 8 is an explanatory diagram showing the configuration of the water purification device. 37 is a box-shaped ornamental fish breeding tank with an open top surface. A box-shaped photocatalyst filter tank 31 having an open upper surface is arranged on the aquarium fish breeding tank 37 via a support plate (not shown). The photocatalyst film coating material 32 is housed in the photocatalyst filter tank 31. In this example, in order to increase the contact area, it is preferable to use a water-permeable network structure as the photocatalyst film coating material 32. Reference numeral 35 is a treated water introduction pipe, and 34 is a water supply pump provided in the middle of the treated water introduction pipe 35. The breeding water in the aquarium fish breeding tank 37 sucked into the water pump 34 is introduced into the photocatalyst filter tank 31 through the treated water introduction pipe 35. The breeding water introduced into the photocatalyst filter tank 31 is returned to the appreciation fish breeding water tank 37 through the treated water discharge pipe 36 while in contact with the photocatalyst film coating material 32. A fluorescent lamp type ultraviolet lamp 33 is arranged above the photocatalyst filter tank 31.

【0106】

That is, the water purification device 30 as a pollutant-containing substance purification device includes a photocatalyst filter tank 31 as a photocatalyst unit provided with a photocatalyst film coating material 32 and an ultraviolet irradiation unit that irradiates the surface of the photocatalyst film coating material 32 with ultraviolet rays. Water supply as a means for introducing contaminants to guide the ultraviolet lamp 33 and breeding water containing ammonia, which is harmful to fish, to the photocatalyst filter tank 31 and bring them into contact with the surface of the photocatalyst film coating material 32 irradiated with ultraviolet rays. It is composed of a pump 34, a treated water introduction pipe 35, and a treated water discharge pipe 36.

【0107】

In the purification device according to the sixth invention of the present application, for example, a liquid containing a volatile pollutant such as water mixed with trichloroethane can be used as the decomposition target compound. In this case, a liquid storage unit for accommodating a liquid containing a volatile pollutant and a gas injection means for injecting gas into the liquid storage unit are further provided, and gas is injected into the liquid storage unit from the gas injection means. It is preferable to use a pollutant-containing material purification device configured to guide the pollutant vaporized by the above to the photocatalyst unit via the pollutant-containing material introducing means. A specific example is shown in Fig. 9.

【0108】

FIG. 9 is an explanatory diagram showing the configuration of a volatile pollutant removing device. In FIG. 9, 46 is a liquid container. Treated water containing volatile contaminants is supplied to the liquid containing portion 46 through a treated water supply pipe 46b connected near the bottom surface of the liquid containing portion 46. Further, a compressed air blowing pipe 46a is provided as a gas injection means, and the compressed air is blown into the treated water through the compressed air blowing pipe 46a. In the liquid storage unit 46, by performing air bubbling, air bubbles blown into the treated water move into the air with the volatile pollutants contained in the treated water, so that the volatile pollutants are volatile pollutants. Can be moved to the air layer above the treated water. Reference numeral 41 denotes a reactor provided outside the liquid storage unit 46. A photocatalyst film coating material 42 is attached to the inner peripheral surface of the reactor 41 having a rectangular cross section and a rectangular shape over the entire circumference. Further, inside the reactor 41, a fluorescent lamp type ultraviolet lamp 43 extending along the central axis of the reactor is arranged. Reference numeral 45 denotes a processing gas introduction pipe that connects the liquid storage unit 46 and the reactor 41 and guides the air containing the pollutants volatilized from the inside of the liquid storage unit 46 to the reactor 41. A suction fan 44 is provided in the middle of the processing gas introduction pipe 45. A pipe connected to the next process is connected to the downstream surface of the reactor 41.

【0109】

The volatile pollutant removing device 40 includes a liquid storage unit 46, a compressed air blowing pipe 46a as a gas injection means, a reactor 41 as a photocatalyst unit composed of a photocatalyst film coating material 42, and a reactor 41. An ultraviolet lamp 43 as an ultraviolet irradiation part that irradiates the surface of the constituent photocatalyst film coating material 42 with ultraviolet rays, and the surface of the photocatalyst film coating material 42 that is irradiated with ultraviolet rays by guiding air containing volatile pollutants to the reactor 41. It is composed of a treated gas introduction pipe 45 and a suction fan 44 as means for introducing a pollutant-containing substance for contact with the water.

【0110】

Of course, the purification device using the photocatalyst film coating material of the present invention is not limited to the one shown in the figure, and can be appropriately changed depending on the decomposition target.

【0111】

[Example]

The present invention will be described in more detail with reference to the following examples, but the following examples do not limit the present invention, and all modifications and implementations within the scope of the gist of the present invention are included in the technical scope of the present invention. ..

【0112】

Example 1: Relationship between arc ion plating conditions, titanium oxide crystal structure, and photocatalyst properties In this example, the relationship between the crystal structure of the photocatalyst film and the photocatalyst characteristics according to the first invention was examined when the oxygen partial pressure, the argon partial pressure, and the substrate temperature were variously changed.

【0113】

Specifically, a 10 × 10 × 1 mmt aluminum base material was degreased with acetone, washed with ethanol, and then mounted on a sample holder in the arc ion plating apparatus chamber. A metal titanium target having a purity of 99.9% was used as a cathode for generating arc discharge. A mixed gas of oxygen and argon was used as the reaction gas.

【0114】

The film forming conditions are as follows, and the parameters (oxygen partial pressure, argon partial pressure, and substrate temperature) that have a large influence on the crystal structure of the titanium oxide photocatalyst film and its photocatalyst characteristics are variously changed. It has been confirmed that parameters other than the above (bias voltage at the time of ribbon bird and film formation, processing time, etc.) have almost no effect on the crystal structure and photocatalytic characteristics of the film.

【0115】

Pretreatment (Pribbon Bird) Atmosphere Vacuum exhaust up to 1.33mPa Arc discharge cathode titanium target Bias Direct Current (DC) 700V Processing time 2 minutes, metal titanium intermediate layer thickness 200 nm (0.2 μm) Formation Atmosphere Oxygen 266mPa (2mTorr) ~ 15960mPa (120mTorr) Partially argon at 0 ~ 3458mPa (26m Torr) mixture [Total 3990mPa (30m Torr) when mixed with argon And said. ] Arc discharge cathode titanium target Bias DC (DC) 10V Base material temperature room temperature ~ 500 ° C Film formation time 2 minutes, titanium oxide layer thickness 0.3 μm [0116]

A sample was cut out from the titanium oxide-coated aluminum material thus obtained, and a sample for cross-sectional observation was prepared by irradiating with a convergent ion beam to form a thin film. Next, by the film cross-sectional observation method using the transmission electron microscope (TEM) described above, the <110> direction is oriented within 45 ° from the perpendicular (normal line) on the surface of the photocatalyst film in the columnar crystal of rutile type titanium oxide. The volume% occupied by the crystal grains was measured.

【0117】

Further, the titanium oxide-coated aluminum material obtained under each of the above-mentioned film forming conditions is placed in a 50 mL quartz volume container, sealed, vacuum exhausted at 200 ° C., and then 12.3 μmol of nitrogen monoxide (NO). Introduced, while keeping at 2 ° C, wavelength 365nm, intensity 2mW / cm²NO was decomposed by a photocatalytic reaction by irradiating with the ultraviolet rays of. The obtained reaction product was collected in a sampling tube and subjected to gas chromatography.₂Was quantified. NO is N due to photocatalytic reaction₂And N₂Decomposed into O, N₂N decreases after the test as NO decreases as₂The larger the amount produced, the higher the photocatalytic properties in the sample.

【0118】

For comparison, anatase-type titanium oxide powder and rutile-type titanium oxide powder (150 mg each) were uniformly placed on a 10 × 10 mm dish having the same area as the above arc ion plating sample plate, and 50 mL of quartz was formed. A NO decomposition test was performed by forming a film in the container under the same film formation conditions, and N₂The amount produced was measured.

【0119】

Table 1 shows the film formation conditions, the crystal structure of the obtained photocatalyst film, and the N produced by the NO decomposition test.₂The result of the amount of production is shown.

【0120】

[table 1]

<img file="JP2001300326A_D0001.tif" />【0121】

It can be considered from Table 1 as follows. First, as a result of NO decomposition test with titanium oxide powder, N in rutile type titanium oxide powder₂The amount generated was 0.12 μmol, and that of the anatase-type titanium oxide powder was 0.65 μmol, confirming that the anatase-type titanium oxide powder had higher photocatalytic properties.

【0122】

Next, when the oxygen partial pressure is less than 6 mTorr (798 mPa) or the substrate temperature is less than 200 ° C, and the film is formed under conditions that do not meet the preferable requirements of the first invention of the present application, a titanium oxide film is formed, but anatase. N compared to type titanium oxide powder₂It can be seen that the amount produced is small and the photocatalytic properties are inferior.

【0123】

On the other hand, when the oxygen partial pressure and the substrate temperature are raised to the preferable ranges of the first invention of the present application, the &lt;110&gt; direction of the rutile type titanium oxide tends to be oriented perpendicularly to the film surface, and the photocatalyst characteristics are also improved. However, when the volume ratio of the above &lt;110&gt; oriented crystal grains in the columnar crystal of rutile type titanium oxide (hereinafter, abbreviated as &lt;110&gt; oriented volume ratio) becomes 50% or more, N exceeds that of anatase type titanium oxide powder.₂It was confirmed that the amount of production was obtained. This tendency became more remarkable when the oxygen partial pressure and the substrate temperature were formed in the more preferable ranges of the first invention of the present application, and the photocatalytic property was remarkably improved. The pressure inside the chamber is 100m Torr (133 × 10).²When mPa) was exceeded, no arc discharge occurred.

【0124】

In addition, although not shown in the table, the same experiment was conducted by changing the voltage and frequency of the DC bias (DC bias) and AC bias (RF bias) applied to the substrate during the pre-ribbon bird and film formation. However, it was confirmed that there was almost no effect on the crystal structure and photocatalyst characteristics.

【0125】

Example 2: Effect of film thickness of photocatalyst film and film thickness of intermediate layer according to the first invention In this embodiment, the film thickness of the titanium oxide film and the film thickness of the metallic titanium intermediate layer are the photocatalyst characteristics (N).₂The effects on (evaluated by the amount of production) and adhesion (evaluated by the critical peeling load) were investigated.

【0126】

First, the oxygen partial pressure is 30 mTorr (3990 mPa), the base material temperature is 500 ° C, and the bias applied to the base material is fixed at 700 V DC at the time of ribbon bird and 10 V DC at the time of film formation, and arc ion play is performed in the same manner as in Example 1. It was processed. As shown in Table 1, the film structure thus obtained has a &lt;110&gt; orientation volume fraction of 99% and has high photocatalytic properties.

【0127】

Next, the film thickness of the metallic titanium intermediate layer between the titanium oxide film and the aluminum base material is set to 5 to 550 nm, and the titanium oxide film is formed by keeping the above film forming conditions constant and changing the ribbon bird time and the film forming time in various ways. The film thickness of was changed in the range of 0.05 to 30 μm.

【0128】

The photocatalytic properties of the sample thus obtained were evaluated by the NO decomposition test in the same manner as in Example 1, and the adhesion of the photocatalyst film was evaluated by the scratch test. For the scratch test, a diamond indenter with a diameter of 200 μm (for Rockwell hardness test) is used, and the sample is applied while continuously applying a vertical load to the indenter at a load loading speed of 100 N / min and a sample moving speed of 10 mm / min. It was moved and the critical peeling load was calculated. These results are shown in Table 2.

【0129】

[Table 2]

<img file="JP2001300326A_D0002.tif" />【0130】

First, when the relationship between the thickness of the titanium oxide film and the photocatalyst characteristics is examined, the anatase-type titanium oxide is anatase-type titanium oxide even when the film thickness is 0.05 μm, which does not meet the preferable requirement (0.1 μm or more) of the first invention of the present application. It can be seen that the characteristics similar to those of the powder can be obtained, but the above characteristics are further improved when the film thickness is 0.1 μm or more. Increasing the film thickness improves the photocatalytic characteristics, but if the film thickness exceeds 1 μm, the effect of increasing the photocatalytic characteristics due to the increase in film thickness becomes saturated, and conversely, if the film thickness exceeds 5 μm, the film becomes The accumulated residual stress increased and the adhesion decreased. Since the photocatalyst characteristics are constant even if the film thickness of the metallic titanium intermediate layer is changed, it is considered that the film thickness of the intermediate layer has no effect on the photocatalyst characteristics.

【0131】

Next, the relationship between the film thickness and the adhesion of the Ti-containing metal intermediate layer will be examined. When the film thickness of the intermediate layer is controlled to 10 to 500 nm, which is a preferable thickness of the first invention of the present application, excellent adhesion can be obtained. As the film thickness of the intermediate layer increases, the adhesion is further improved, but when the film thickness exceeds 500 nm, the titanium oxide layer is cracked due to plastic deformation of the soft titanium metal layer, and it becomes easy to peel off. ..

【0132】

Example 3: Effect of metal element on photocatalyst film coating material according to the second invention We investigated how the types and amounts of metal elements in the metal substrate affect the photocatalytic activity. In order to make it easy to understand the influence of the elements, a binary alloy of Ti and metal elements was prepared by the mechanical alloying method (sintering by mixing fine powder). The types and amounts of metal elements are as shown in Table 3. We also examined multiple alloys consisting of Ti and Mn, Cr, Fe, Co, Ni, Pd and Pt, and multiple alloys consisting of Ti and Zn, Cd, Sn, Pb, Cu, Ag and Au. These multi-element alloys were prepared by adding elements other than Ti at the same atomic% so that the total composition was the amount shown in Table 3. The Ti-Al alloy (No. 17) is a comparative example.

【0133】

The obtained alloy is processed to 50 mm × 50 mm × 1 mmt, the surface of this metal base material is pickled, finished so that the average surface roughness Ra is 0.3 μm, and the metal titanium layer is obtained by the arc ion plating method. (Conductive intermediate layer) and titanium oxide layer (photocatalyst film) were coated. Metallic titanium (Ti: 99 atomic% or more) is used for the cathode target, arc discharge is performed in a vacuum of 1.33 mPa, a bias of 700 V DC is applied to the metal base material, and a film is formed for 2 minutes, and the thickness is 0.2 μm (0.2 μm). A 200 nm) metallic titanium intermediate layer was formed. Then, oxygen gas was introduced into the chamber to form a titanium oxide film having a thickness of 0.4 μm in an atmosphere of 13300 mPa at a substrate temperature of 300 ° C., a bias voltage of 10 V, and a film formation time of 2 minutes.

【0134】

The photocatalytic property is that potassium iodide (KI) is oxidized by photocatalytic action, and iodine I generated by the oxidation₂Was evaluated by a method of quantifying. That is, in 150 mL of the potassium iodide aqueous solution (0.1 mol / L), the photocatalyst film surface is the light receiving surface (25 cm).²), Soak the sample so that the strength is 3 mW / cm.²The amount of iodine produced when irradiated with the ultraviolet rays of the above for 30 minutes was measured by absorptiometry. Table 3 summarizes the amount of iodine produced (photocatalytic) of each sample.

【0135】

In addition, as described above, ordinary steel S50C, which is mostly composed of Fe element, stainless steel SUS430, which is mostly Fe, Cr element, and stainless steel SUS304, which is mostly Fe, Cr, Ni element, are pickled and washed as described above. A conductive intermediate layer and a photocatalyst film were formed, and the photocatalytic property was evaluated. The results are shown in Table 4. Furthermore, a sample (No. 21) in which a quartz glass plate, which is a non-metallic material, is coated with a photocatalyst film, and a sample in which an intermediate layer of polyester resin is coated on the surface of SUS304 (thickness 0.2 μm) and then coated with a photocatalyst film. (No.22) was also evaluated, and the results are shown in Table 4.

【0136】

[Table 3]

<img file="JP2001300326A_D0003.tif" />【0137】

[Table 4]

<img file="JP2001300326A_D0004.tif" />【0138】

According to the data of the quartz glass plate in Table 4, the photocatalytic property of the photocatalytic film formed by arc ion plating is that the amount of iodine produced is 32 × 10.^-5It is mol. From Table 3, it can be seen that the photocatalyst characteristics are improved when the reduction reaction promoting metal specified in the second invention of the present application is contained in an amount of 5 atomic% or more. Cr and Pt showed particularly remarkable photocatalytic properties. The multi-dimensional alloy also shows the same improvement effect as the binary alloy.

【0139】

However, the Ti-Al binary alloy (No. 17) has almost the same amount of iodine production as that of the quartz glass plate, and it was confirmed that Ti and Al have no effect of improving the photocatalytic properties. ..

【0140】

Since ordinary steel and stainless steel (No. 18 to 20) also contain a metal that promotes the reduction reaction, the amount of iodine produced is large, and the object of the present invention has been achieved. The cross-sectional photograph shown in FIG. 4 is that of No. 20. Regarding this No. 20, when the anode current ratio Ai / Ao was measured with no coating layer and after coating by the above method, it was 1 × 10.^-4Met. On the other hand, the No. 22 anode current ratio Ai / Ao coated with non-conductive polyester as an intermediate layer is also 1 × 10.^-4Although the existence of pinholes was confirmed, it can be seen that the photocatalytic properties are at the same level as the quartz glass plate, and the movement of electrons is hindered by the polyester resin layer.

【0141】

Example 4: Production of Photocatalytic Membrane Coating Material According to Second Invention Using Ti-Containing Organic Compound A sample was prepared in the same manner as in Example 3 except that the conductive intermediate layer and the photocatalyst film were formed by using the Ti-containing organic compound instead of the arc ion plating method, and the photocatalyst characteristics were evaluated. First, an organic solvent solution containing 10% by volume of tetraacetylacetonate titanium was applied to the surface of the substrate by a dip method and fired at 500 ° C. for 30 minutes to form a conductive intermediate layer having a thickness of 0.2 μm. Further, the same organic solvent solution was applied onto this layer by a dip method and calcined at 500 ° C. for 30 minutes to form a photocatalyst film having a thickness of 0.3 μm.

【0142】

The titanium oxide obtained by this method was an anatase type crystal and had a random crystal structure that was not oriented in a specific direction. The profile of FIG. 5 described above is that of No. 42. For this sample, the anode current ratio Ai / Ao with and after coating was measured and found to be 1 × 10.^-4Met. The results of evaluating the photocatalytic properties of each sample are shown in Tables 5 and 6.

【0143】

[Table 5]

<img file="JP2001300326A_D0005.tif" />【0144】

[Table 6]

<img file="JP2001300326A_D0006.tif" />【0145】

The tendency of photocatalytic properties was the same as in Example 3, but the amount of iodine produced was slightly smaller in the anatase-type titanium oxide of Example 4.

【0146】

Example 5: Effect of pinhole density on the photocatalyst film coating material according to the second invention The effect of pinhole density (anode current ratio) on photocatalyst characteristics was investigated. Stainless steel SUS304 was cut into 50 mm × 50 mm × 1 mmt, and metal substrates having various Ra as shown in Table 7 were prepared by various polishing methods. Ra in the hairline is a value in the direction orthogonal to the line. An intermediate layer having a thickness of 0.2 μm and a titanium oxide film having a thickness of 0.3 μm were formed on these metal substrates in the same manner as in Example 4.

【0147】

The anode current value of the obtained sample was measured by the method described above. As a typical example, Fig. 10 shows a photocatalyst film coating material using a stainless steel SUS304 base material whose surface roughness was Ra = 0.3 μm by pickling, and a polarization curve of stainless steel SUS304 with the same roughness (Ra). Indicated. The anode current ratio Ai / Ao at this time is 1 × 10.^-4Is. The photocatalytic properties are summarized in Table 7.

【0148】

[Table 7]

<img file="JP2001300326A_D0007.tif" />【0149】

Anode current ratio is 3x10^-8In the case of, the amount of iodine produced is 22 × 10.^-5It is about mol, which is about the same as the above-mentioned quartz glass plate and Ti-Al alloy base material. Therefore, in this case, it is the photocatalytic property of the titanium oxide film itself. That is, it can be seen that the number of pinholes is too small and the effect of localizing the reduction reaction on the surface of the base material at the bottom of the pinholes is hardly obtained.

【0150】

On the other hand, the anode current ratio is 1.0 × 10.^-7When it reaches the level, the amount of iodine produced suddenly becomes 60 × 10.^-5It is increased to mol or more, and it can be seen that the localization of the reduction reaction site functions efficiently and contributes to the improvement of the photocatalyst characteristics. In addition, the anode current ratio is 1x10^-5~1×10^-3Then, the amount of iodine produced is 89 × 10.^-5It increases to mol, and it is considered that the pinhole density becomes optimum in this vicinity. However, the anode current ratio is 3x10^-3Then, the amount of iodine produced begins to decrease, and 1 × 10^-1Beyond, 28 × 10^-5It drops sharply to mol. This is because the pinhole density becomes too high and the area ratio of titanium oxide that excites the photocatalyst decreases. From the above, in order to effectively improve the photocatalytic characteristics, the anode current ratio should be 1 × 10.^-7~1×10^-1I was able to confirm that it would be good.

【0151】

Example 6: Effect of conductive intermediate layer on photocatalyst film coating material according to the second invention The relationship between the thickness of the conductive intermediate layer and the adhesion of the photocatalyst film was investigated. First, a conductive intermediate layer and a photocatalyst layer were formed on the surface of stainless steel SUS304 by arc ion plating in the same manner as in Example 3. A sample was prepared in which only the thickness of the metallic titanium intermediate layer was different under the same conditions as in Example 3 except that the time for forming the metallic titanium layer was changed from 3 seconds to 80 minutes. As described above, the area from the point where the amount of O is 10 atomic% to the point where the amount of Ti is 10 atomic% is defined as the intermediate layer, and the thickness of the intermediate layer is obtained and shown in Table 8. It was.

【0152】

Further, according to Example 4, a sample was prepared in which only the thickness was different by changing the firing temperature when forming the intermediate layer. As described above, the amount of the most abundant element among the metal elements contained in the base material is 10 atomic%, so that the amount of the most abundant element among Ti, O, and C is The intermediate layer was defined up to 10 atomic%, the thickness was calculated, and it is shown in Table 9.

【0153】

In order to examine the adhesion of the photocatalyst film for each sample, the critical peeling load was measured by the scratch test method described above. The results of the critical delamination load are shown in Tables 8 and 9 together with the photocatalytic properties.

【0154】

[Table 8]

<img file="JP2001300326A_D0008.tif" />【0155】

[Table 9]

<img file="JP2001300326A_D0009.tif" />【0156】

In both the arc ion plating method and the titanium-containing organic compound firing method, when the thickness of the intermediate layer is 5 nm, the peeling critical load is about 2 to 3 N, and the adhesion that can withstand practical use cannot be obtained. However, when the thickness of the intermediate layer exceeds 10 nm, the critical peeling load becomes 20 to 30 N, and when the thickness of the intermediate layer reaches 30 nm, it is as high as about 50 N in the arc ion plating method and about 40 N in the firing method. As a result, it was possible to obtain adhesion that could withstand practical use. It was found that when the thickness of the intermediate layer exceeds 30 nm, the change in the critical peeling load almost disappears and a constant adhesion is maintained.

【0157】

On the other hand, the amount of iodine produced by the arc ion plating method is approximately 90 × 10.^-5It is an extremely excellent level of mol or more, and even with the titanium-containing organic compound firing method, it is 80 × 10^-5It exhibited excellent photocatalyst properties at the mol level. However, when the thickness of the intermediate layer exceeds 3 μm, the amount of iodine produced begins to decrease slightly, and when the thickness exceeds 5 μm, it is 30 to 40 × 10.^-5It was found that it decreased to about mol. This is because the electrical resistance of the entire layer gradually increases as the thickness of the intermediate layer increases, making it difficult for the electrons excited by the photocatalytic reaction to reach the surface of the metal substrate at the bottom of the pinhole, resulting in a reduction reaction site. It is considered that this is because it becomes difficult to obtain the localization effect with the oxidation reaction site. Therefore, it is recommended that the thickness of the intermediate layer be 5 μm or less. 3 μm or less is more preferable, and 1 μm or less is most preferable.

【0158】

Example 7: Durability of photocatalyst film coating material according to the second invention The durability of the photocatalytic properties of the photocatalyst film coating material was examined. An example (No. 20) in which a conductive intermediate layer and a photocatalyst film were coated on stainless steel SUS304 by the arc ion plating method shown in Example 3 and a conductive intermediate between stainless steel SUS304 and stainless steel SUS304 by the firing method shown in Example 4. The durability of the photocatalytic properties was investigated for the example (No. 42) in which the layer and the photocatalyst film were coated. Assuming that it will be used for water purification treatment, the photocatalytic properties after immersing the sample in running water at a flow rate of 2 m / sec for a certain period of time were evaluated as durability. The initial value is the value before immersion. The results are shown in Table 10.

【0159】

[Table 10]

<img file="JP2001300326A_D0010.tif" />【0160】

It can be seen that the photocatalyst film coating material according to the second invention exhibits excellent photocatalytic properties for 500 hours or more, but the one produced by the arc ion plating method is more excellent. The photocatalytic property is exhibited because it is rutile-type titanium oxide having a specific crystal structure of the first invention. The reduction reaction site generated on the metal substrate at the bottom of the pinhole contributes to electron localization, and this reduction reaction site is not adversely affected by the water flow, so that excellent photocatalytic properties should be maintained for a long period of time. Was confirmed.

【0161】

Regarding the sample of the quartz glass plate base material of Example 3 No. 21, when Cr metal was adhered to the surface of the photocatalyst film of this sample by wet plating, the photocatalyst characteristics equivalent to those of the present invention were exhibited. When the same durability experiment as in Example 7 was carried out, the photocatalyst characteristics deteriorated after 10 hours, and after 100 hours, it decreased to the same level as in the case where Cr was not attached. This is thought to be because Cr falls off due to the water flow.

【0162】

Furthermore, the same durability experiment was conducted on a sample in which 4 photocatalyst layers and 3 metal Cr layers were alternately laminated on SUS304 by sputtering, and V-shaped grooves were cut at 0.1 mm intervals with a laser. This example also had the same photocatalyst characteristics as the present invention at the initial stage, but the photocatalyst characteristics deteriorated after 50 hours, and after 300 hours, the photocatalyst characteristics were lower than that of the quartz glass plate base material (No. 21). It was declining. It is probable that the photocatalyst layer itself fell off due to the water flow.

【0163】

Example 8: Examination as a deodorizing device in the garbage treatment according to the sixth invention A deodorization / sterilization test was performed using the deodorizing device 10 shown in FIG. Garbage consisting of leftover rice, vegetable waste and meat and yeast were put into the food waste processing tank 17, and a gas containing malodorous substances and bacteria was generated at a temperature of about 45 ° C. The gas containing the malodorous substance and bacteria is guided from the garbage treatment tank 17 into the deodorization tank 11 via the treatment gas introduction pipe 15, and while passing through the deodorization tank 11, the ultraviolet lamp 13 is used. Strength 10mW / cm²The surface of the photocatalyst film coating material 12 irradiated with the ultraviolet rays of the above was brought into contact with the surface.

【0164】

In this experiment, the photocatalyst film coating material 12 was cooled to about 5 ° C. In addition, deodorization and sterilization tests were conducted for 5 consecutive hours. Condensed water is discharged to the outside and collected, and when 100 ml is accumulated, put it in another 1 liter container and leave it for 30 minutes, and then ammonia (NH) in the container.₄) The concentration was measured. In addition, the total number of bacteria per 1 g of collected water (CFU / g) was measured by the plate dilution method.

【0165】

As the photocatalyst film coating material, the base material temperature is shown in Table 11 by the arc ion plating method (AIP method) in the same manner as in Example 1 according to the first invention, with the oxygen partial pressure kept constant at 3990 mPa (30 mTorr). Nos. 20 and 42 produced in Examples 3 and 4, and Nos. 22 and 44 for comparison were used. We also examined pure aluminum material that is not coated with a photocatalyst film and stainless steel (SUS304). NH₄The results of concentration and total bacterial count (CFU / g) are shown in Table 11.

【0166】

[Table 11]

<img file="JP2001300326A_D0011.tif" />【0167】

In the case of aluminum material, the one formed with the substrate temperature set to room temperature and 100 ° C is NH compared to the case without the photocatalyst film.₄The concentration decreased to some extent, but remained at about 10 to 15 ppm. Compared to this, the amount of film formed at preferable substrate temperatures of 400 ° C and 500 ° C was reduced to 11 ppm or less. In addition, in the case of stainless steel coated with a conventional photocatalyst film, NH is compared with the case without a photocatalyst film.₄The concentration decreased to some extent, but remained at about 10 to 15 ppm. On the other hand, in the examples of the second invention of the present application, it decreased to 5 ppm or less.

【0168】

From the measurement results of the number of bacteria, even if there is no photocatalytic film, it is sterilized to some extent by ultraviolet irradiation, but both aluminum material and stainless steel are 10⁵It can be seen that bacteria on the order of CFU / g remain. 10 for the film formed with the substrate temperature set to room temperature and 100 ° C⁴It decreased to the order of CFU / g, but the degree of decrease in the number of bacteria was not remarkable. Compared to this, those formed at preferable substrate temperatures of 400 ° C and 500 ° C have a bacterial count of 10.²It decreased to the CFU / g order and showed an excellent bactericidal effect. In addition, the same tendency was shown in the case of stainless steel.

【0169】

Example 9: Examination as an air purification device in a clean room according to the sixth invention The effect of preventing organic gas pollution in the local space in class 100000 (clean room without high cleanliness) was investigated by the device shown in Fig. 7. The contamination state of the wafer 26 was evaluated by the contact angle of water. When a hydrophobic substance adheres to the surface of the wafer, it repels water and becomes difficult to get wet. Therefore, the higher the degree of contamination of the organic gas, the larger the contact angle.

【0170】

Using the same sample as in Example 8, a clean wafer was placed at the position shown in FIG. 7 and 50 mW / cm on the surface of the photocatalyst film coating material.²After holding the wafer for a predetermined time in the state of being irradiated with the ultraviolet rays of the above, the contact angle of water was measured for the removed wafer. Table 12 shows the change in contact angle over time.

【0171】

[Table 12]

<img file="JP2001300326A_D0012.tif" />【0172】

In the case of aluminum material without a photocatalytic film, organic gas contamination occurred with the passage of time, and the contact angle increased, but it settled down to around 24 ° after 30 hours. When the substrate temperature is set to room temperature and 100 ° C, the contact angle is 20 ° or less after 50 hours, and the contamination of organic gas is reduced to some extent, but it cannot be completely suppressed. Can not. In comparison, the contact angle of the film formed at the preferable substrate temperatures of 400 ° C and 500 ° C was reduced to 17 ° or less. In addition, the same tendency was shown in the case of stainless steel, but in particular, the second invention example (No.20, No.42) of the present application showed an extremely good effect of suppressing organic gas pollution with a contact angle of 9 ° or less. It was.

【0173】

Example 10: Examination as a water purification device according to the sixth invention A water purification experiment was conducted using the water purification device shown in Fig. 8. An ornamental fish breeding tank 37 with a capacity of 50 liters is used to breed 20 goldfish, and NH produced by excretion of goldfish₄The concentration was examined. The size of the photocatalyst filter tank 31 is W320 mm × L115 mm × H100 mm. Ten mesh filters having an outer diameter of W320 mm × L115 mm × H0.1 mm and having an opening of 1 mm × 1 mm were stacked and loaded therein. The strength at a height of 50 mm above the overflowing water surface when water is poured into this filter tank 31 is 10 mW / cm.²The ultraviolet lamp 33 was used to irradiate the ultraviolet light so as to be. As the photocatalyst film coating material, as in Example 8, sample filters for the case of using a pure aluminum material and the case of using a stainless steel were prepared and used for the experiment. The results are shown in Table 13.

【0174】

[Table 13]

<img file="JP2001300326A_D0013.tif" />【0175】

For aluminum filters without a photocatalyst film, NH over time₄An increase in concentration was observed. NH after 3 weeks₄The concentration decreases slightly, probably because the grown microorganisms purify the water. NH is formed by setting the substrate temperature to room temperature and 100 ° C.₄Although the increase in is reduced to some extent, it cannot be completely suppressed. Compared to this, those formed at preferable substrate temperatures of 400 ° C and 500 ° C are NH.₄The concentration was reduced to 0.9 ppm or less, showing excellent photocatalytic activity. In addition, the same tendency was shown in the case of the stainless steel filter, but in particular, the second invention example (type corresponding to No. 20) of the present application is NH.₄The concentration hardly increased, showing an extremely good effect of suppressing organic gas pollution.

【0176】

Example 11: Examination as a water purification device according to the sixth invention An experiment to purify trichloroethylene, which is a volatile pollutant contained in water, was carried out using the device shown in Fig. 9. Water containing 100 ppm of trichloroethylene was supplied to the bottom of the liquid container 46, and compressed air was blown into the water from a compressed air blowing pipe 46a from a compressor (not shown). The air above the liquid container 46 was taken into the reactor 41 to decompose trichlorethylene. The irradiation amount of ultraviolet rays is 10 mW / cm²And said. The same photocatalyst coating material as in Example 8 was attached to the inside of the reactor 41 for the experiment. The trichloroethylene concentration (initial concentration) in the air above the liquid container 46 and the trichloroethylene concentration (concentration after treatment) in the air at the downstream outlet of the reactor 41 were measured. The results are shown in Table 14. The trichlorethylene concentration of the treated water discharged from the drain pipe 46c was reduced to 10 ppm regardless of the type of photocatalyst.

【0177】

[Table 14]

<img file="JP2001300326A_D0014.tif" />【0178】

In the case of aluminum material without a photocatalytic film, both the initial concentration and the concentration after treatment are 10 ppm, and the decomposition effect of trichlorethylene is not observed. When the substrate temperature was set to room temperature and 100 ° C, the concentration after the treatment was slightly reduced to 8 to 9 ppm, and the effect of decomposing trichloroethylene by the photocatalyst was obtained, but the remarkable effect was obtained. It is not allowed. In comparison, those formed at preferable substrate temperatures of 400 ° C and 500 ° C showed excellent photocatalytic ability with the concentration after treatment reduced to 4 to 5 ppm. In addition, the same tendency was shown in the case of stainless steel.

【0179】

[Effect of the invention]

Since the coating material of the first invention of the present application has a rutile-type titanium oxide film in which the crystal orientation is controlled, it has extremely excellent photocatalytic properties superior to those of anatase-type titanium oxide crystal powder, even though it is a film. There is. The production method according to the third invention is extremely useful because a titanium oxide coating material having excellent durability can be efficiently obtained.

【0180】

Further, in the second invention of the present application, it was possible to provide a photocatalyst film coating material having good adhesion between the photocatalyst film and the metal substrate due to the presence of the conductive intermediate layer without using a binder. The photocatalytic film coating material of the second invention is configured to use the conductive intermediate layer and the pinholes in the photocatalytic film to move the electrons excited by the photocatalytic reaction into the metal substrate at the bottom of the pinholes. Therefore, it is possible to prevent holes and electrons from recombining. Further, since the reduction reaction site using the metal base material cannot cause inconvenience such as dropping off, it is possible to maintain excellent photocatalytic properties for a long period of time. In the production method of the fourth invention, since the conductive intermediate layer and the photocatalyst film can be efficiently laminated, the photocatalyst film coating material can be easily produced.

【0181】

The photocatalytic membrane coating materials of the first and second inventions are used in various applications in which the photocatalyst is utilized, for example, liquid purification, gas purification, decomposition, by implementing the purification method of the fifth invention by the purification device of the sixth invention. It can be suitably used for such purposes.

[Simple explanation of drawings]

[Figure 1]

It is sectional drawing to explain the conventional photocatalyst.

[Figure 2]

It is sectional drawing to explain the conventional photocatalyst.

[Fig. 3]

It is sectional drawing for demonstrating the photocatalyst film coating material material of this invention.

[Fig. 4]

It is a transmission electron micrograph of the cross section of the photocatalyst membrane coating material of this invention (which is both 1st invention and 2nd invention) obtained by the arc ion plating method.

[Fig. 5]

It is a composition analysis result by Auger electron spectroscopy of a sample in which a conductive intermediate layer was formed on stainless steel SUS304 by a firing method.

[Fig. 6]

It is sectional drawing for demonstrating the deodorizing apparatus used for the kitchen waste processing by one Embodiment of the sixth invention.

[Fig. 7]

It is sectional drawing for demonstrating the air purification apparatus for a clean room by one Embodiment of 6th invention.

[Fig. 8]

6 is a schematic cross-sectional view for explaining the water purification apparatus according to the embodiment of the sixth invention.

[Fig. 9]

6 is a schematic cross-sectional view for explaining a volatile pollutant removing device according to an embodiment of the sixth invention.

[Fig. 10]

It is an anode polarization curve.

[Explanation of symbols]

10 Deodorizer 20 Air purification device 30 Water purification device 40 Volatile pollutant remover