JP2002316057A - Photocatalyst and functional body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photocatalyst having high decomposability even at a low temperature of about room temperature (0 to 40 deg.C) and to provide a functional body using the same. SOLUTION: The photocatalyst in which a surface layer consisting of MOXCY (M is a metal) is provided on a surface of a photocatalyst film consisting essentially of titanium oxide is formed. Preferably M is a kind of metal selected from a group composed of Y, La, Sc, Gd, Er, Yb, Sm and Pr or a mixture thereof. Further preferably atomic number ratio (Y/X) of oxygen and carbon is in a range between 0.02 and 0.2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photocatalyst, a functional body such as a lamp, a lighting fixture, an indoor building material, and a filter of a deodorizing device using the same.

[0002]

2. Description of the Related Art It is known to use photocatalytic films for deodorizing, antifouling and antibacterial.

When a photocatalytic film is irradiated with ultraviolet light and absorbs its light energy, electrons and holes are generated in a semiconductor which forms a photocatalytic film and exhibits a photocatalytic action. The electrons and holes are said to react with oxygen and water on the film surface to generate active oxygen and other active radicals, and to decompose organic dirt and odor components by redox reduction.

As the photocatalytic substance, many kinds of metal oxides are known as seen in metal oxides exhibiting semiconductor properties, and among them, titanium oxide is most promising at present. This is because titanium oxide is a substance that has a remarkable photocatalytic action and is available at a safe, industrially reasonable price and in a required amount.

In recent years, attention has been paid to the usefulness of photocatalytic films, and there is an active movement to form photocatalytic films on a wide range of articles such as used lamps, lighting equipment, indoor building materials, and filters of deodorizing devices.

[0006]

However, in such a photocatalyst, the activity of the photocatalyst is greatly reduced when the ambient temperature is lowered, depending on the use conditions. Especially about room temperature (4
(0 ° C. or lower).

[0007] The present invention has been made in view of the above problems, and has as its object to provide a photocatalyst having high decomposability in a low temperature range of about room temperature and a functional body using the same.

[0008]

A photocatalyst according to the first aspect of the present invention comprises: a photocatalyst film containing titanium oxide as a main component; and a surface composed of MO _X C _Y (M is a metal) on at least a part of the surface of the photocatalyst film. And a layer.

In the present invention and the following inventions, the definitions and technical meanings of terms are as follows unless otherwise specified.

The photocatalyst of the present invention has a photocatalyst film, but does not require a substrate. The photocatalyst film has a photocatalyst material as its main component, but allows other materials to be contained as necessary.

The photocatalyst film is formed in a film shape on a base material mainly containing titanium oxide TiO ₂ . Metal compounds having a photocatalytic action include titanium oxide TiO ₂ , WO ₃ , F
eTiO ₃ , Fe ₂ O ₃ , CdFe ₂ O ₄ , SrTiO
₃ , ZnO, CdFeO ₃ , Bi ₂ O ₃ , In ₂ O ₃ ,
CdO, SnO ₂ and the like. One or more of these substances can be used as a mixture with titanium oxide TiO ₂ .

Among the above various photocatalytic substances, titanium oxide TiO ₂ has a remarkable photocatalytic action, and is safe, industrially reasonable, and easily available as described above. Most promising. Titanium oxide has rutile and anatase crystal structures. It is said that the anatase form is superior in photocatalysis. Therefore, it is preferable to use anatase type titanium oxide. However, in practice, the rutile form is often mixed with the anatase form, and when ultrafine particles of titanium oxide are used, a practical photocatalytic action is obtained even if the above crystal structures are mixed. Therefore, both may be mixed. The decomposability changes depending on the mixing ratio.

Further, Ti, which has not been known until now,
Amorphous titanium oxide containing O and C as main components can also be used. The film made of the amorphous titanium oxide has a very high decomposition power and can be formed at a low temperature. In addition, by performing a heat treatment in a relatively high temperature state on the photocatalytic film made of the amorphous titanium oxide, while maintaining a high decomposition force by crystallization,
A photocatalytic film mainly composed of titanium oxide having good film strength, adhesion strength to a substrate, and durability has been developed.

The photocatalytic substance is applied by applying a metal compound such as titanium by, for example, a dipping method or a spraying method.
A film may be formed by heating and baking, or a dispersion of ultrafine particles of a photocatalyst substance may be prepared, applied and dried to deposit fine particles. That is, the photocatalytic film is allowed to be formed using various known film forming methods. In the case of the ultrafine particle dispersion method, the ultrafine particles have an average particle size of 3
It is preferable to use extremely fine particles of 0 nm or less, preferably 7 to 10 nm. In addition, it is preferable that the fine particles have a shape as close to a spherical shape as possible and have good crystallinity with little variation in particle diameter.

When forming a photocatalyst film containing fine particles such as ultrafine particles of a photocatalytic substance as a main component, a strong film can be obtained by using an appropriate binder.
As the binder in this case, it is preferable to use a Si compound, and even if the Si compound is used, a material that is fired at an appropriate temperature or a material that is curable at room temperature can be used. As the cold-setting binder, for example, a binder obtained by adding a curing catalyst to at least one selected from the group consisting of a methyl group and an organosilane oligomer containing a methyl group can be used. As the curing catalyst, for example, at least one selected from the group consisting of acids, alkalis, zinc compounds, titanium compounds, and zirconium compounds can be used. Further, a coating solution in which titanium oxide ultrafine particles are dispersed in a binder solution composed of a composition containing an oxidation catalyst,
The photocatalyst film can also be formed by coating on a substrate or an underlayer and drying. In addition, when a photocatalytic film is formed using a cold-setting binder, the photocatalytic film can be configured to be cured at 15 to 100 ° C.

At least on the surface of the photocatalyst, MO _X C _Y
A surface layer made of (M is a metal) is formed. This surface layer is allowed to be formed on the surface of the photocatalytic film or on the surface of the titanium oxide particles forming the photocatalytic film, including the inside of the photocatalytic film. In order to form such a surface layer, the surface of the photocatalytic film can be formed by applying an organic solvent solution of a metal complex such as M (M is a metal) acetylacetonate and subjecting it to a thermal decomposition treatment. By this thermal decomposition treatment, O bonded to titanium oxide particles on the surface
The H group is eliminated to form a surface layer of MO _X C _Y (M is a metal), and the surface layer hardly contains an OH group.
Further, the thickness of the surface layer is formed to be 10 nm or less.

At this time, when a heat treatment is performed using a hydrolyzable material such as a nitrate or a metal alkoxide which is generally used as a protective film, an OH group is formed on the surface layer once. Therefore, it is desirable to apply the above-described metal complex as an organic solvent since almost no effect is produced.

According to the first aspect of the present invention, about room temperature (0 to
A photocatalyst having a high decomposition ability even in a low temperature range of (40 ° C.) can be provided. Although the detailed mechanism has not been elucidated, it is considered that the influence of water adsorbed on the surface is eliminated by eliminating the OH groups on the surface of the titanium oxide.

The photocatalyst of the second aspect is the photocatalyst of the first aspect, wherein M is Y, La, Sc, Gd,
It is characterized by being one selected from the group of Er, Yb, Sm and Pr or a mixture thereof.

In the present invention, a metal suitable as M constituting the surface layer is specified. In particular, it is easy to form stably,
Y that is readily available at an industrially reasonable price is Y
(Yttria) and La (lantern) are promising.

According to a third aspect of the present invention, there is provided the photocatalyst according to the first or second aspect, wherein the element number ratio of oxygen and carbon (Y /
X) is in the range of 0.02 to 0.2.

Thus, the ratio of the number of atoms of oxygen to carbon is regulated.
Good MO by setting_XC _Y(M is metal) table
A face layer can be formed.

The functional body according to the fourth aspect of the present invention includes a functional body main body;
The photocatalyst according to any one of claims 1 to 3, wherein the photocatalyst is formed on a surface of the functional body as a base.

In the present invention, the functional body includes, for example, building materials such as tiles, window glass, and ceiling panels, interior materials such as wallpaper and curtains, kitchen and sanitary equipment, home appliances, lighting equipment, and lighting equipment. Shows filters for odor or dust collection.

The "functional body main body" means a part or the whole of the functional body excluding the photocatalytic film. For example, when the functional body is a tile, a normal tile portion is referred to as a functional body in the present invention, and if a photocatalytic film is formed on the front of the tile, a photocatalytic film is formed on a part of the functional body. Will be formed.

When the functional body is a lamp, the photocatalytic film can form a photocatalytic film on the outer surface of the glass bulb of the lamp. The light emission principle of the lamp is not limited as long as the light emitting portion is surrounded by a glass bulb and includes a wavelength of 400 nm or less. For example, it is allowed to be an incandescent lamp, a discharge lamp, or the like. In the case of an incandescent lamp, a halogen lamp having a higher color temperature has a higher emission ratio at a wavelength of 400 nm or less than a general lighting lamp. In the case of a discharge lamp, either a low-pressure discharge lamp or a high-pressure discharge lamp may be used. Examples of the low-pressure discharge lamp include a fluorescent lamp. In the case of a fluorescent lamp, if necessary, the phosphor to be used can be selected to appropriately increase the emission of 400 nm or less. Such a fluorescent lamp has a relatively small decrease in visible light and a large amount of ultraviolet light for irradiating the photocatalyst, as compared with a fluorescent lamp for general illumination, so that the decomposing power can be increased. Therefore, it is suitable as a lamp for activating the photocatalyst. However, a fluorescent lamp using a phosphor of three-wavelength emission or a halophosphate phosphor, which has been widely used for general illumination, may be used. In addition, mainly 400 nm
A germicidal lamp, a black light, a chemical lamp, or the like for the purpose of utilizing the following light emission may be used. On the other hand, the high-pressure discharge lamp may be, for example, a mercury lamp, a metal halide lamp, a high-pressure sodium lamp, or the like. The glass bulb may be an arc tube surrounding the discharge medium, or an outer tube further surrounding the arc tube containing the light emitting section. As described above, while the room is illuminated by the light emitted from the lamp, the photocatalytic film can be activated by the ultraviolet light emitted to decompose the odorous gas and deodorize. In particular, in the case of a lamp, since the photocatalyst film is disposed at a position where the intensity of ultraviolet light is high, almost the entire photocatalyst film can be activated well and strong deodorization can be performed.

Next, when the functional body is a lighting fixture,
Since the luminaire is used at a position close to the lamp which is a source of ultraviolet rays, the photocatalytic film can be well activated with a strong ultraviolet intensity. The part where the photocatalytic film is formed is preferably a part of the light control means of the lighting equipment. The light control means may be a plurality of light control means including one or any combination of reflectors, gloves, shades, translucent covers, chandeliers, louvers, and the like. Since the light control means controls the light emission of the lamp in order to obtain a desired light distribution and appearance, since the light control means is also irradiated with the ultraviolet light of the lamp, a photocatalytic film is formed on this portion. By doing so, the photocatalytic film can be activated as required,
Therefore, it is effective to decompose and deodorize odorous gas. Moreover, since the odorous gas is decomposed by the photocatalytic film, the indoor deodorization is effectively performed. Furthermore, the lighting fixture is sized and structured so as to be accommodated in, for example, a refrigerator, an air conditioner, an air purifier, and the like, and is disposed in these devices, whereby deodorization can be performed in the device.

Thus, in the present invention, even if dirt, bacteria or odorous substances adhere to the portion where the photocatalyst film is formed during use of the functional body, the photocatalyst film is irradiated with ultraviolet light, Is decomposed and removed. In addition, since the photocatalyst film and, if necessary, the underlayer can be formed by room-temperature curing, the photocatalyst film can be formed on a functional body made of a flammable material such as a curtain, wallpaper, or wood. Therefore, the material of the portion of the functional body where the photocatalytic film is formed is not limited.

According to the fourth aspect of the present invention, it is possible to provide a functional body having a high photocatalytic decomposition power even in a low temperature range.

[0030]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a conceptual enlarged cross-sectional view showing a first embodiment of a photocatalyst according to the present invention.

The substrate 1 is made of soda lime glass, and a photocatalytic film is formed on the surface of the substrate 1. The photocatalyst film 2 is obtained by dispersing ultrafine particles of anatase type titanium oxide having an average particle diameter of 10 nm in isopropyl alcohol, and further adding a Si compound mainly composed of polysiloxane to 2 to 30 nm.
The coating solution containing the weight% is applied to the substrate 1, and 200 to
The structure is mainly composed of a deposited film of ultrafine particles 4 of anatase type titanium oxide fired at 600 ° C.

The surface layer 3 is formed by adding yttrium acetylacetonate to an organic solvent such as ethanol at 0.05 to 0.1.
The photocatalyst film 2 is coated with a coating solution prepared by dissolving
It is formed by performing a thermal decomposition treatment at a temperature of 0 ° C., and has an average film thickness of about 3 nm or less and about an atomic layer. The surface layer 3 is attached on the surface of the titanium oxide ultrafine particles 4 and may be present inside the photocatalyst film 2.

The process for forming the surface layer 3 will be described with reference to FIG. FIG. 2A schematically illustrates ultrafine particles 4 of titanium oxide formed on a base. In this state, OH groups are bonded on the titanium oxide particles 4. Next, FIG. 2B shows a state in which yttrium acetylacetonate is applied to the titanium oxide film, and yttrium acetylacetonate 3 a is applied on the titanium oxide particles 4. O bonded to the titanium oxide particles 4
Y group acetylacetonate 3a is also attached to the H group.

FIG. 2C shows a state in which a heat treatment is performed at about 250 ° C. in this state. _YO X _{C Y} less than a few molecular layers thick on the titanium oxide particles 4 (3 nm or less) is formed as the surface layer 3. At this time, the OH groups bonded to the titanium oxide particles 4 have been eliminated.

FIG. 3 is a graph showing the measurement results of the relationship between the ambient temperature and the decomposability of the photocatalyst of this embodiment. In the figure, the horizontal axis indicates temperature (° C.), and the vertical axis indicates degradability (relative value). Curve A shows the case of the photocatalyst film of this embodiment, and curve B shows only a titanium oxide film similar to that of this embodiment as a comparative example (no surface layer).
Are shown below.

In the test, a test piece was prepared by forming a gas soot (soot) film on the surface of the catalyst body, and the decomposability was measured with the same amount of ultraviolet irradiation and different temperatures of the catalyst film. It is. As is clear from the figures, in all cases, the higher the temperature of the catalyst film, the higher the decomposability, but in the case of the comparative example, the lower the decomposability at 40 ° C. or lower. In the case of the present embodiment 4 as compared with the comparative example
The decomposability at 0 ° C. is about 20% higher than that of the comparative example, and the decomposability at 20 ° C. is about three times higher.

From these results, it is possible to enhance the decomposability of the photocatalyst in a low temperature range of about room temperature by forming the photocatalyst as in the present embodiment.

FIG. 4 is a partial sectional front view showing a ring-shaped fluorescent lamp as a first embodiment of the functional body of the present invention.

In the figure, 11 is a glass bulb, 12 is a photocatalytic film, 13 is a phosphor layer, 14 is a filament electrode,
Reference numeral 15 denotes a base.

The glass bulb 11 functions as a base for the photocatalytic film 12, and hermetically accommodates therein a functional part as a fluorescent lamp. That is, several hundred Pa of rare gas mainly composed of mercury and argon as a discharge medium is sealed inside the glass bulb 11 whose both ends are separated and opposed and annularly curved, and the phosphor layer 13 is carried on the inner surface.
Further, a pair of filament electrodes 14 are sealed at both ends.

The photocatalyst film 12 has the same structure as the photocatalyst shown in FIG. Note that the glass bulb 11 functions as a base.

The phosphor layer 13 is formed using a three-wavelength light emitting phosphor.

The filament electrode 14 is used for the glass bulb 1
1 are sealed at both ends via a flare stem.

The base 15 is made of a base body 15a made of synthetic resin.
And a pair of base pins 15b insulated from the base body 15a. Base body 15a
Is formed in two pieces, and is fixed by a fitting mechanism (not shown) by bridging between both ends of the glass bulb 11. Both ends of the filament electrode 14 are connected to base pins 15b, respectively.

When illumination is performed using the annular fluorescent lamp of the present embodiment, the photocatalytic action of the photocatalytic film 12 causes
Organic contaminants adhering to the surface of the fluorescent lamp are decomposed, and odor substances in the air in contact therewith are decomposed to deodorize the surroundings.

FIG. 5 is a perspective view showing a tunnel lighting fixture as a functional body according to a second embodiment of the present invention. In the figure, 21 is a lighting fixture main body, 22 is a front frame, 23 is a translucent glass cover, 24 is a lamp socket, 25 is a high-pressure discharge lamp, and 26 is a reflector.

The lighting fixture main body 21 is formed by molding a stainless steel plate into a box shape having an opening on the front surface, and has a mounting bracket 21a on the back surface.

The front frame 22 is formed by molding a stainless steel plate, and has a light projecting opening 22a in the center, a hinge 22b on one side, and a latch (not shown) on the other side. The hinge 2a is pivotally attached to one side of the front side of the lighting fixture body 21 so as to be openable and closable, and is fixed to a closed position by a latch.

The translucent glass cover 23 is waterproofly attached to the front frame 22 via a silicone rubber packing 22c. The translucent glass cover 23 transmits visible light and has relatively high transmittance characteristics in at least a part of an ultraviolet region having a wavelength of 400 nm or less. A photocatalytic film 23a having the same configuration as that of FIG. 1 is formed on the front surface of the translucent glass cover 23. Note that the translucent glass cover 23 functions as a base.

The lamp socket 24 is connected to the lighting fixture body 21.
It is arranged in.

The high-pressure discharge lamp 25 has 340 to 400 n
In the wavelength range of m, ultraviolet rays having an intensity of 0.05 W or more per 1000 lm of a visible light beam are emitted.

The reflecting plate 26 is provided in the lighting fixture main body 21 so that light emitted from the high-pressure discharge lamp 25 is reflected by the reflecting plate 26 and exhibits a required light distribution characteristic. Are located.

On the back side of the reflector 26 of the lighting fixture body 21, a ballast, a terminal block and the like are arranged.

Then, the lighting fixture of the present embodiment is installed in the tunnel via the mounting bracket 21a and used for illumination, and illuminates the inside of the tunnel.

Also, the ultraviolet rays in the wavelength range of 340 to 400 nm mainly emitted from the high-pressure discharge lamp 25 simultaneously with the illumination pass through the translucent glass cover 23 together with the visible light and enter the photocatalytic film 23a. Photocatalytic film 23a
Is activated by ultraviolet rays, and performs self-cleaning by decomposing organic dirt such as soot and smoke adhering thereto.

[0057]

Effects of the Invention According to the present invention 1, MO _X adhering photocatalyst film composed mainly of titanium oxide and the photocatalytic film
_{Since (M} is metal) C Y is and a surface layer made of, it is possible to provide a photocatalyst capable of enhancing the degradability of the photocatalyst in a low temperature range of about room temperature (0 to 40 ° C.).

According to the invention of claim 2, in the photocatalyst of claim 1, M is Y, La, Sc, Gd, Er, Y
By using one selected from the group consisting of b, Sm, and Pr or a mixture thereof, a photocatalyst that has a higher photocatalytic action and can improve the action at low temperatures can be provided.

According to a third aspect of the present invention, in the photocatalyst according to the first or second aspect, the ratio (Y / X) of the oxygen coefficient x to the carbon coefficient Y is in the range of 0.02 to 0.2. By defining this, a good MO _X C _Y (M is a metal) surface layer can be formed.

According to the invention of claim 4, it is possible to provide a functional body having the effects of claims 1 to 3.

[Brief description of the drawings]

FIG. 1 is a conceptual enlarged cross-sectional view of a principal part showing an embodiment of a photocatalyst body of the present invention.

FIG. 2 is also a schematic diagram of a process for forming a surface layer.

FIG. 3 is a graph showing measurement results of temperature and decomposability in the embodiment of the photocatalyst of the present invention.

FIG. 4 is a partial cross-sectional front view showing a ring-shaped fluorescent lamp as a first embodiment of the functional body of the present invention.

FIG. 5 is a perspective view showing a lighting device for a tunnel as a second embodiment of the functional body of the present invention.

[Explanation of Symbols] 1. Base 2 Photocatalytic film 3 Surface layer (MO _X C _Y (M is metal)) 4 Titanium oxide fine particles

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4D048 AA22 BA07X BA18X BA41X BA45X BC07 EA01 4G069 AA03 AA08 BA04A BA04B BA48A BB04A BB04B BB15A BB15B BC39A BC40A BC40B BC42A BC44A CA01 CA17 CD10 DA19 EA08 EC08

Claims (4)

[Claims] 1. A photocatalyst film containing titanium oxide as a main component; and a surface layer made of MO _X C _Y (M is a metal) on at least a part of the surface of the photocatalyst film. Photocatalyst. 2. M is Y, La, Sc, Gd, Er, Y
2. The photocatalyst according to claim 1, wherein the photocatalyst is one selected from the group consisting of b, Sm and Pr, or a mixture thereof. 3. The photocatalyst according to claim 1, wherein the atomic ratio of oxygen and carbon (Y / X) is in the range of 0.02 to 0.2. 4. A functional body comprising: a functional body main body; and the photocatalyst according to claim 1 formed on a surface of the functional body main body as a base.