JP2003190809A - Method for manufacturing composite material formed with photocatalyst film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a composite material with a formed photocatalyst film comprising a titanium-containing oxynitride which exhibits photocatalytic activity and/or hydrophilicity upon irradiation with visible light. <P>SOLUTION: The surface of a substrate is coated with a film of 0.01-3 μm average thickness containing a titanium-containing oxide or a precursor thereof and a prescribed nitriding treatment is carried out in an atmosphere of a prescribed gas to convert the film to a photocatalyst film comprising a titanium- containing oxynitride which exhibits photocatalytic activity and/or hydrophilicity upon irradiation with visible light. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a composite material having a photocatalytic coating that exhibits photocatalytic activity and / or hydrophilicity upon irradiation with visible light. Suitable for use as an interior / exterior material that requires functions.

[0002]

2. Description of the Related Art In recent years, there is a need for environment-purifying products having functions such as antibacterial, deodorant, and antifouling due to the growing interest in pollution control, health, comfort, and cleanliness. Attention has been paid. Above the "photocatalyst" refers to the absorption of light energy, the excited electrons are superoxide anion of reactive oxygen species by reducing oxygen (· O ₂ ^-) to generate a, active oxygen holes oxidize water It is a substance that oxidizes and decomposes organic substances and the like that come into contact with the surface of the photocatalyst by generating seed hydroxyl radicals (OH.

Further, when the photocatalyst is titanium oxide, it can exhibit superhydrophilicity of 5 ° or less at a contact angle of water. By utilizing this property, in outdoor use, anti-fouling treatment for oil, inorganic dust, carbon, etc., which are the main components of urban pollution, anti-fog treatment for ensuring visibility, and in indoor use, antibacterial / erasing Sanitary treatment such as odor can be performed.

For example, Japanese Patent No. 2756474 proposes a hydrophilic substrate having a titanium oxide photocatalyst bonded to the surface. Furthermore, by utilizing the property of the n-type semiconductor, the metal material can also be subjected to galvanic protection.

The reaction in which the reactive oxygen species are generated occurs by photocatalysis.
The band gap energy of the medium is
Lugie (1.36eV (2.18 × 10^-19J)) just larger than
Sufficiently, the bottom of its conduction band and the top of the valence band are
O that produces volatile oxygen species₂/ O₂ ^-(-0.13 eV (-0.21 x 10^-19
J)) levels and O₂/ H₂O (1.23eV (1.97 × 10^-19J)) level
It must be in a position to pinch. This redox level
Is an equilibrium level, it causes a reaction to generate reactive oxygen species.
Requires a certain amount of overvoltage, which is below the conduction band.
The edge level is O₂/ O₂ ^-The valence electron is located on the negative side of the level.
O of the upper level of the belt₂/ H₂Position on the positive side of the O level
Is desirable.

However, the anatase-type titanium oxide currently practically used as a photocatalyst substance has a band whose upper end level of the valence band is located sufficiently deeper than the O ₂ / H ₂ O level on the positive side. Gap energy is 3.2 eV (5.13 × 10 ^-19 J)
Therefore, the properties of photocatalytic activity and hydrophilicity cannot be exhibited by irradiation with visible light, and the above properties can be exhibited only by irradiation with ultraviolet rays.

For example, when sunlight or a fluorescent lamp is used as the light source, the spectral distribution spectrum of ultraviolet rays is at most 3
It is ~ 4%, and the intensity of near-ultraviolet light is 1-2 in daylight.
mW / cm ² is only about 1 μW / cm ^{2 for} indoor fluorescent lamps. Therefore, it is desired to develop a photocatalytic material capable of exhibiting photocatalytic activity and hydrophilic properties even when irradiated with visible light, in order to effectively utilize light energy and to exert a sufficient function even in a fluorescent lamp environment.

In order to exhibit a photocatalytic function by irradiation with visible light, it is a necessary condition that the bandgap energy of the photocatalyst is about 3 eV (4.8 × 10 ⁻¹⁹ J) or less capable of absorbing visible light, and various methods are available. Proposed.

For example, in Japanese Patent Laid-Open No. 11-197512, an ion implanter is used to implant anatase-type titanium oxide with a transition metal such as vanadium or chromium.
It is disclosed that visible light activity is exhibited by heat treatment in the atmosphere. However, the method and apparatus described in the above publication are expensive, and it is difficult to apply them to a large area.

Also, Masayoshi Miyoshi et al., Coloring Material, 73 (12), 580 (20
(00) discloses that anatase-type titanium oxide is subjected to hydrogen plasma treatment to form oxygen deficiency, and thereby visible light activity is exhibited. However, if oxygen vacancies are formed and oxygen atoms are removed, an unstable crystal structure is likely to be formed, and it is difficult to maintain the photocatalytic action for a long period of time.

Furthermore, R. Asahi et al., Science, 293 , 2
69 (2001), using the RF magnetron sputtering method, the upper end of the valence band was shifted to the negative side by mixing the nitrogen 2p orbit with the oxygen 2p orbit that constitutes the valence band of anatase-type titanium oxide. The titanium oxynitride (TiO _2-x N _x ) photocatalytic thin film prepared is disclosed. The TiO _{2 -x} N _x photocatalytic thin film described in the above reference is a photocatalytic material that can exhibit photocatalytic activity and hydrophilicity by irradiation with visible light, but this thin film has a TiO ₂ target of N by the RF magnetron sputtering method. _Since it is manufactured by depositing in a ₂ + Ar gas atmosphere, the equipment is expensive, it is difficult to control the amount of nitrogen contained in the thin film, and it is difficult to control the multi-component element to any composition. There were problems such as difficulties.

[0012]

SUMMARY OF THE INVENTION In view of the above-mentioned conventional techniques, an object of the present invention is to provide a photocatalyst film made of titanium oxynitride which exhibits photocatalytic activity and / or hydrophilicity by irradiation with visible light. It is to provide a method for producing a formed composite material, which is suitable for use as an interior / exterior material that requires, for example, environmental purification or anticorrosion functions.

[0013]

The inventors of the present invention have found that a titanium-containing oxynitride obtained by substituting an oxygen site of a titanium-containing oxide containing titanium dioxide or a titanium composite oxide with a nitrogen element has a photocatalytic activity under visible light irradiation. In order to develop a method capable of advantageously producing a titanium-containing oxynitride photocatalyst thin film, focusing on the fact that it exhibits hydrophilicity and / or hydrophilicity, and further improves abrasion resistance and corrosion resistance, a substrate was investigated. The film formed on the surface is a titanium-containing oxide or its precursor substance, and the average film thickness of the film is 0.01
It was found that a composite material having a photocatalytic coating of titanium-containing oxynitride having a uniform composition in the film thickness direction can be produced by subjecting it to a relatively simple nitriding treatment if the thickness is up to 3 μm, and completed the present invention. Came to let.

That is, the gist of the present invention is as follows. (1) After coating the surface of the base material with a film containing a titanium-containing oxide or its precursor substance having an average film thickness of 0.01 to 3 μm, under an atmosphere of ammonia gas, ammonia-containing gas or a mixed gas of hydrogen and nitrogen , A nitriding treatment by heating at a temperature of 400 to 1200 ° C. to modify the coating into a photocatalytic coating composed of titanium-containing oxynitride that exhibits photocatalytic activity and / or hydrophilicity by irradiation with visible light. A method for producing a composite material having a photocatalyst coating formed thereon (first invention).

(2) The surface of the substrate has an average film thickness of 0.01 to 3 μm.
nitriding treatment by irradiating with far ultraviolet rays or vacuum ultraviolet rays in an atmosphere of ammonia gas, ammonia containing gas or a mixed gas of hydrogen and nitrogen after coating with a film containing titanium-containing oxide of m or its precursor substance. By applying, the coating is modified into a photocatalytic coating made of titanium-containing oxynitride that exhibits photocatalytic activity and / or hydrophilicity by irradiation with visible light.
A method for producing a composite material having a photocatalytic coating (second invention).

(3) The average film thickness on the surface of the substrate is 0.01 to 3 μm.
m after coating with a film containing a titanium-containing oxide or its precursor substance, and then subjecting the film to nitriding treatment with nitrogen ions generated by glow discharge in an atmosphere of a mixed gas of hydrogen and nitrogen, A method for producing a composite material having a photocatalyst film formed thereon, which comprises modifying the photocatalyst film made of titanium-containing oxynitride that exhibits photocatalytic activity and / or hydrophilicity by irradiation with visible light (third invention).

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail below. The photocatalytic anatase-type titanium oxide currently in practical use cannot express a photocatalytic activity by irradiation with visible light, but can express a photocatalytic activity only by irradiation with ultraviolet rays. This is because the upper level of the valence band of the oxide composed of the 2p orbit of oxygen is O ₂ / H ₂ O, which is the oxidation level of water.
The reason for this is that the band gap energy is increased due to the deeper position on the positive side.

Therefore, as a method of exhibiting a photocatalytic activity by irradiation with visible light, oxynitride obtained by doping an oxide photocatalyst with a nitrogen element is drawing attention. When the oxygen site of the oxide is doped with a nitrogen element, N _2p having a higher energy level than O _{2p of} oxygen is also used for the configuration of the valence band, and as a result, the upper level of the valence band is increased. It is considered that visible light can be absorbed as a result of shifting to the negative side and narrowing the band gap.

The oxynitride photocatalyst is anatase type TiO _2-x N _x or titanium, niobium or tantalum perovskite or layered perovskite material such as LaTa.
O ₂ N, CaTaO ₂ N, SrTaO ₂ N, BaTaO ₂ N, LaTiO ₂ N, Ca _1-x La _x T
Although iO _3-x N _x , CaNbO ₂ N, SrNbO ₂ N, BaNbO ₂ N, etc. are known, practically, the photocatalytic substance is titanium-based titanium because of its cost, safety, and stability. It is preferably a contained oxynitride. The term “titanium-based titanium-containing oxynitride” used herein refers to a compound in which the proportion of titanium element in the transition metal elements forming the conduction band is 50 atom% or more.

Since the photocatalyst composite material produced by the method of the present invention coats the titanium-containing oxynitride photocatalyst on the substrate, it has a photocatalytic activity and / or
Alternatively, since it exhibits hydrophilicity and the crystal structure is doped with a nitrogen element, it is excellent in wear resistance and corrosion resistance.

In order for the titanium-containing oxynitride photocatalytic film to exhibit superhydrophilicity, it is preferable that the photocatalytic film contains a crystal structure of anatase type, rutile type, brookite type or the like. The mechanism of complex oxides such as perovskite type is unknown, but the contact angle with water is usually only 10 to 20 °. Furthermore, in order to maintain the hydrophilicity for a long period of time, silica or silicon oxynitride is added to the solid content of the photocatalytic coating at 10 to 10%.
It is preferable to mix 80% by mass, more preferably 20 to 50
Mass% is mixed.

In the method for producing a composite material having a photocatalyst film according to the present invention, first, the surface of the base material has an average film thickness of 0.01 to 3
Coat with a coating containing μm titanium-containing oxide or its precursor material. The reason why the average film thickness of the film is limited to the above range is that if the film thickness is less than 0.01 μm, it is difficult to form a uniform film and the photocatalytic function is not effectively exhibited. Also 3μ
This is because if it exceeds m, it becomes difficult to uniformly contain nitrogen in the film thickness (depth) direction of the coating film by the subsequent nitriding treatment. Even if a film with a thickness of more than 3 μm is formed, it can be modified into titanium-containing oxynitride only within a range of about 3 μm from the surface.

The base material used in the present invention includes inorganic materials such as ceramics, tiles, concrete, glass and bricks, metal materials such as aluminum, stainless steel, plated steel sheets, chemical conversion treated steel sheets and coated steel sheets, acrylics and polycarbonates. Examples thereof include organic materials such as resin and wood, but are not particularly limited thereto.

The shape of the substrate is, for example, block,
Examples thereof include plates (sheets), films, structural materials, etc., but are not particularly limited thereto. In addition, the size and thickness of the base material are not particularly limited.

When it is necessary to protect the substrate from the oxidative decomposition action of the titanium-containing oxynitride photocatalytic film, it is preferable to provide a barrier layer between them. As the barrier layer, in addition to oxidation protection of the base material, heat ray reflection, radio wave reflection, it is also possible to impart functionality such as conductivity, for example, silicone resin, silica, alumina, zirconia, ITO, titanium nitride, Examples thereof include, but are not limited to, silicon carbide.

As a method for coating a film containing a titanium-containing oxide or its precursor substance on a substrate, a vapor phase method such as a chemical vapor deposition method, a reactive vapor deposition method or a reactive sputtering method, or
A liquid phase method such as a sol-gel method may be mentioned, but the method is not particularly limited thereto.

Form of the above coating by a vapor phase method, for example, a vapor deposition method.
To give an example of the composition method, a chamber in which a base material is installed
ー 1 × 10⁻³After depressurizing to Pa, oxygen partial pressure is 1 to 9
× 10 ^-2Adjust to Pa and irradiate the evaporation source TiO with an electron beam
The substrate on the substrate heated to 100 to 400 ° C.
A case-type titanium oxide film may be formed. At this time, acid
If the temperature is not sufficient, 10-
Heat treatment may be applied for up to 60 minutes.

An example of a method for forming the above-mentioned coating by a liquid phase method, for example, a sol-gel method will be given. Acetylacetone, diethylene glycol, ethyl acetoacetate and other chelating agents are added to 1 mol of titanium alkoxide in an alcohol solvent.
˜2 mol, followed by adding 0.01 to 0.1 mol of carboxylic acid such as oxalic acid and acetic acid, inorganic acid such as boric acid, hydrochloric acid, nitric acid, sulfuric acid and phosphoric acid as an acid catalyst, and then gradually adding 1 to 4 mol of water. The resulting partial hydrolysis solution as a coating solution or when blending other elements, an alcohol solution obtained by mixing the above chelating agent with an alkoxide of another element in the partial hydrolysis solution, or oxychloride, oxynitrate,
A coating solution prepared by mixing an alcoholic solution of an inorganic salt such as oxyphosphate, oxyacetate, nitrate, ammonium salt, or chloride, or an organic acid salt such as acetate or oxalate at a predetermined ratio is used as a base material. The coating may be formed by coating.

As another method, an aqueous crystalline titanium oxide sol such as anatase or brookite, an amorphous titanium oxide aqueous solution such as peroxotitanic acid or orthotitanic acid, or a mixed solution thereof is added to the above-mentioned inorganic salt or organic salt. The aqueous solutions are mixed at a predetermined ratio to obtain a coating solution. At this time, when the coating solution gels by the addition of the above-mentioned inorganic salt or organic salt solution,
This can be prevented by previously adding an organic acid such as lactic acid, malic acid or citric acid to the titanium oxide aqueous solution to form a titanium complex. Moreover, when synthesizing the titanium oxide aqueous solution, the above-mentioned inorganic salt or organic salt may be mixed in advance in the starting material. The coating solution may be applied to a base material in the same manner to form the coating film. The method for forming a coating film on a substrate is to adjust the solid content of the sol solution to 0.1 to 10% by mass, preferably 0.5 to 5% by mass in terms of oxide, and apply to the substrate by spraying, dipping, brushing or the like. To form a dry film.

The present invention proposes several nitriding treatment methods which are post-treatment methods in which a photocatalytic coating is relatively easy to prepare after forming a coating containing a titanium-containing oxide or its precursor substance. Note that these proposed nitriding methods can be selectively used according to the characteristics of the base material.

Examples of the nitriding treatment method include a salt bath dipping method of dipping in a salt bath of cyanate, a gas nitriding method, an ion nitriding method, and the like. Considering the environment and the like, the gas nitriding method and the ion nitriding method are used. It is preferable to use the nitriding method.

As the gas nitriding method used in the present invention, an atmosphere of a nitrogen-containing gas such as ammonia gas, an ammonia-containing gas or a mixed gas of hydrogen and nitrogen is used because it is easy to extract oxygen from an oxide and introduce nitrogen. Below,
A method of nitriding is used by heating at 400 to 1200 ° C or by irradiation with far ultraviolet rays or vacuum ultraviolet rays.

The ammonia-containing gas is a gas in which a non-oxidizing gas such as argon or nitrogen or a reducing gas such as hydrogen or hydrocarbon is mixed with ammonia gas, and the mixing ratio of the non-oxidizing gas or the reducing gas is , Volume ratio 5 to 90
Volume%, preferably 10 to 80% by volume. The mixing ratio of hydrogen gas in the mixed gas of hydrogen and nitrogen is 1 to 8 by volume.
It is 0% by volume, preferably 5 to 50% by volume.

When a base material having a high heat resistance is used, it is 1 to 400 ° C. to 1200 ° C. in one of the above-mentioned gas atmospheres.
Heat treatment for 120 minutes, preferably at 500 to 700 ° C. for 5 to 60 minutes. At this time, if the temperature is too high or the time is too long, nitriding may proceed excessively, and the photocatalytic activity may decrease due to a change in crystal structure, transition to metallic conductivity, or the like.

When a base material having a low heat resistance is used, ultraviolet rays at a temperature not higher than the heat resistant temperature of the base material in the above gas atmosphere,
It is preferable to nitrid the film by irradiating far ultraviolet rays or vacuum ultraviolet rays having a wavelength of 315 nm or less.

The ultraviolet light source may be any one that emits ultraviolet light having a wavelength of 315 nm or less, and examples thereof include a sterilizing lamp having a high intensity and good radiation efficiency, a low pressure mercury lamp, an excimer lamp, and the like. There is no particular limitation. The wavelength of ultraviolet rays emitted is 254n with a germicidal lamp.
m, 185 nm for low-pressure mercury lamp, discharge gas for excimer lamp depends on discharge gas, but discharge gas is XeCl, KrCl, Xe ₂ , K
When r ₂ and Ar ₂ , 308 nm, 222 nm, 172 nm, 146 n
m, 126 nm.

An example of irradiation conditions when a low pressure mercury lamp is used as a light source for ultraviolet rays is as follows:
Irradiation with 1 to 50 mW / cm ² for 1 to 60 minutes, preferably 5 to ²⁰ mW / cm ² for 5 to 30 minutes is preferable. Even in the gas nitriding method by ultraviolet irradiation, nitriding may proceed excessively if the irradiation amount or irradiation time is too long, and in this case as well, since the photocatalytic activity is reduced as described above, the irradiation conditions should be set appropriately. Must be set.

Further, as the ion nitriding method used in the present invention, the nitriding treatment time is short, the nitriding layer thickness is easily controlled,
Because of the advantage that partial nitriding can be performed only at the required locations, a method of nitriding with nitrogen ions generated by glow discharge at a low temperature of 400 ° C. or lower in a mixed gas atmosphere of hydrogen and nitrogen is used. In this case, the mixing ratio of hydrogen gas in the mixed gas atmosphere of hydrogen and nitrogen is 10 to 90 by volume.
Volume% is preferable, more preferably 20 to 70% by volume, and the pressure of the mixed gas of hydrogen and nitrogen is 0.05 to
It is preferably 50 Pa, more preferably 0.1 to 20 Pa
And

When nitriding is carried out by the above method, oxygen deficiency may occur, but it does not particularly affect the catalytic activity and hydrophilicity.

[0040]

EXAMPLES Next, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples.

Example 1 A coating solution prepared by mixing anatase-type titanium oxide sol and peroxotitanic acid in a mass ratio of 7: 3 was spray-coated on a white enamel material (base material) coated with titanium glaze, and after drying. Pre-baking was performed at 200 ° C. for 10 minutes to prepare a composite material having a film having an average film thickness of 0.2 μm. Then, the composite material formed with the film is
The film was modified into a photocatalyst film made of titanium oxynitride by performing a nitriding treatment at 600 ° C. for 10 minutes in a stream of ammonia gas at 1 / min. At this time,
The photocatalytic film is anatase type, and its average film thickness is 0.2.
was μm. The characteristics of the photocatalytic coating were measured and evaluated by the methods described below. The evaluation results are shown in Table 1.

Example 2 As Example 1 except that a mixed gas of ammonia and nitrogen (volume ratio NH ₃ : N ₂ = 7: 3) was used as the atmosphere gas for nitriding instead of ammonia gas. By the same method, a composite material having a film having an average film thickness of 0.2 μm formed was prepared, and the film was modified into a photocatalytic film made of titanium oxynitride. At this time, the photocatalytic coating was anatase, and its average film thickness was 0.2 μm. Table 1 shows the evaluation results of the characteristics of the photocatalytic coating.

Example 3 Example 1 was repeated except that a mixed gas of hydrogen and nitrogen (volume ratio N ₂ : H ₂ = 10: 1) was used instead of ammonia gas as the atmosphere gas for nitriding. By the same method as described above, a composite material having a film having an average film thickness of 0.2 μm was prepared, and the film was modified into a photocatalytic film made of titanium oxynitride. At this time, the photocatalytic coating was of anatase type, and its average film thickness was 0.2 μm. Table 1 shows the evaluation results of the characteristics of the photocatalytic coating.

(Example 4) As the nitriding treatment method, an ion nitriding method of nitriding by glow discharge in a mixed gas atmosphere of hydrogen and nitrogen (volume ratio N ₂ : H ₂ = 2: 1, gas pressure 3 Pa) is used. Other than the above, the average film thickness was 0.2 by the same method as in Example 1.
A composite material having a film with a thickness of μm was prepared, and the film was modified into a photocatalytic film made of titanium oxynitride. At this time, the photocatalytic coating was of anatase type, and its thickness was 0.2 μm. Table 1 shows the evaluation results of the characteristics of the photocatalytic coating.

(Example 5) 0.2 mass% of a silicone-based surfactant was added to a coating solution prepared by mixing anatase type titanium oxide sol and peroxotitanic acid in a mass ratio of 7: 3.
The added solution was spray-coated on a white acrylic plate (base material) coated with a clear silicone resin and dried at 80 ° C. for 60 minutes to prepare a composite material having a film having an average film thickness of 0.15 μm. Then, the composite material formed with the coating,
Ultraviolet rays (ultraviolet intensity at wavelength 254 nm is 10 mW / cm ² , wavelength 18
The film was modified into a photocatalyst film made of titanium oxynitride by performing a nitriding treatment by irradiating a 5 nm UV intensity of 4 mW / cm ² ) at room temperature for 10 minutes. At this time, the photocatalytic film is anatase type, and the average film thickness is
It was 0.15 μm. The characteristics of the photocatalytic coating were measured and evaluated by the methods described below. The evaluation results are shown in Table 1.

Example 6 A 0.01 μm titanium nitride layer (barrier layer) formed by a reactive vapor deposition method on the surface of an acrylic film, and an upper layer of the titanium nitride layer by a reactive magnetron sputtering method. A film composed of the formed anatase type titanium oxide layer having an average film thickness of 0.2 μm was formed. The sputtering condition is to use metallic titanium for the target,
The atmosphere gas is a mixed gas of Ar and O ₂ (volume ratio Ar: O ₂ = 4:
6) and the total gas pressure was 3 Pa. Then, the film on which the above coating is formed is subjected to ultraviolet light (ultraviolet light intensity at a wavelength of 254 nm is 10 mW / cm ² and ultraviolet intensity at a wavelength of 185 nm is 4 mW / cm ² ) by a low pressure mercury lamp in a stream of 100 ml / min of ammonia gas.
By nitriding treatment by irradiating for 10 minutes at room temperature,
The above coating was modified into a photocatalytic coating made of titanium oxynitride. Then, the film having the photocatalyst film formed thereon is stacked on the polycarbonate plate so that the back surface faces the polycarbonate plate (base material) and then heat-sealed to form a photocatalyst film made of titanium oxynitride. A composite material was prepared. At this time, the photocatalytic film is anatase type, and the average film thickness is
It was 0.1 μm. The characteristics of the photocatalytic coating were measured and evaluated by the methods described below. The evaluation results are shown in Table 1.

(Example 7) The same method as in Example 1 was repeated except that a coating solution of strontium titanate was used as the titanium-containing oxide instead of titanium oxide.
A composite material with a film having an average film thickness of 0.2 μm was prepared,
The coating was modified into a photocatalytic coating consisting of titanium-strontium oxynitride. At this time, the photocatalytic coating was a perovskite type, and its average film thickness was 0.2 μm. Table 1 shows the evaluation results of the characteristics of the photocatalytic coating.

Comparative Example 1 A coating solution prepared by mixing anatase-type titanium oxide sol and peroxotitanic acid in a mass ratio of 7: 3 was spray-coated on a white enamel material (base material) coated with titanium glaze and dried. By firing at 500 ° C. for 10 minutes, a composite material having a photocatalytic coating formed thereon was produced. At this time, the photocatalytic film is anatase type, and the average film thickness is
It was 0.2 μm. The characteristics of the photocatalytic coating were measured and evaluated by the methods described below. The evaluation results are shown in Table 1.

Comparative Example 2 Example 1 except that the average film thickness of titanium oxynitride was 0.008 μm.
A composite material having a photocatalytic film formed thereon was prepared by the same method as described above. Table 1 shows the evaluation results of the characteristics of the photocatalytic coating.

Comparative Example 3 The same method as in Comparative Example 1 was repeated except that a coating solution of strontium titanate was used in place of titanium oxide as the titanium-containing oxide.
A composite material having a photocatalyst coating was prepared. At this time,
The photocatalytic film is a perovskite type, and its average film thickness is
It was 0.2 μm. Table 1 shows the evaluation results of the characteristics of the photocatalytic coating.
Shown in.

(Test Method) [Antibacterial Test] The antibacterial activity was evaluated according to the light irradiation film adhesion method described in the antibacterial activity evaluation test method for antibacterial products of the Antibacterial Product Technology Council. After inoculating 0.1 ml of a bacterial solution with a bacterial concentration of 1.5 × 10 ⁶ cells / ml onto a 5 cm × 5 cm size test material, cover it with a polyethylene film to bring it into close contact, set it in a transparent petri dish, and set the temperature to 25 The lid was covered under the condition of ℃ and relative humidity of 90% or more, and 1000 lux of visible light was irradiated with a white fluorescent lamp for 4 hours or 8 hours, or left in the dark for 4 hours or 8 hours. After that, surviving bacteria were washed out from the test material with physiological saline and cultured in NA medium at 35 ° C. for 24 hours, and the viable cell count was measured. For the antibacterial activity, the number of viable bacteria was less than 10 when the number of viable bacteria was 1 per test material. Staphylococcus aureus IF0 12732 is used as the bacterium, and the white fluorescent lamp is equipped with an ultraviolet cut film (trade name “ObicC” manufactured by King Seisakusho Co., Ltd.) to set the ultraviolet intensity to 0.
It was set to 1 μW / cm ² or less (ultraviolet intensity was measured by a 365 nm ultraviolet sensor).

[Contact angle] 20 μL of ion-exchanged water was dropped onto the test material using a microsyringe, and the water droplets on the test material were measured with an image processing type contact angle meter (Kyowa Interface Science Co., Ltd.,
CA-X) was used to measure the contact angle of water by the three-point method.
The contact angle is measured in the initial state before irradiation with visible light, after irradiation with visible light of 1000 lux for 8 hours using the white fluorescent lamp, and after being left for 24 hours in a dark place. I went the same way.

[0053]

[Table 1]

From the results shown in Table 1, all the Examples
It can be seen that the antibacterial activity is excellent by irradiation with visible light for 8 hours. Further, it can be seen that Examples 1 to 7 express both photocatalytic activity and hydrophilicity at a high level by irradiation with visible light for 8 hours. On the other hand, in the comparative example, antibacterial activity and hydrophilicity are not exhibited even when irradiated with visible light.

[0055]

According to the present invention, a composite material in which a photocatalytic film made of titanium-containing oxynitride which exhibits photocatalytic activity and / or hydrophilicity is advantageously formed not only by ultraviolet irradiation but also by visible light irradiation is advantageously formed. It has become possible to provide a manufacturing method of. Further, by using the manufacturing method of the present invention, the photocatalytic film can be formed without using an expensive device. Furthermore, the composite member obtained by the manufacturing method of the present invention can be used as, for example, an interior material that requires an environmental purification or anticorrosion function, a scenic material such as a sidewall material, an outer wall material, and the like. Incidentally, the photocatalytic coating composed of titanium-containing oxynitride constituting the composite material is superior in wear resistance and corrosion resistance as compared with the photocatalytic coating composed of oxides such as titanium oxide, and the coating adhesion is also good. is there.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Tatsuya Nobuzawa             1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Made in Kawasaki             Technical Research Institute of Iron Co., Ltd. (72) Inventor Shigeru Takano             1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Made in Kawasaki             Technical Research Institute of Iron Co., Ltd. (72) Inventor Hirohiko Murakami             Tokodai 5-9-7 Stock Association, Tsukuba City, Ibaraki Prefecture             ULVAC Tsukuba Institute for Supermaterials (72) Inventor Chizuru Ogane             Tokodai 5-9-7 Stock Association, Tsukuba City, Ibaraki Prefecture             ULVAC Tsukuba Institute for Supermaterials F-term (reference) 4G047 CA01 CB04 CB08 CC03 CD02                 4G069 AA03 AA08 BA04A BA04B                       BA48A BB06B BB11A BB11B                       BC12B CA10 EA08 FB02                       FB24

Claims (3)

[Claims] 1. An atmosphere of ammonia gas, ammonia-containing gas or a mixed gas of hydrogen and nitrogen after coating a surface of a substrate with a film containing a titanium-containing oxide or its precursor substance having an average film thickness of 0.01 to 3 μm. The film is subjected to a nitriding treatment under heating at a temperature of 400 to 1200 ° C. to be modified into a photocatalytic film made of titanium-containing oxynitride that exhibits photocatalytic activity and / or hydrophilicity by irradiation with visible light. A method for producing a composite material having a photocatalytic coating formed thereon. 2. An atmosphere of an ammonia gas, an ammonia-containing gas or a mixed gas of hydrogen and nitrogen after coating a surface of a substrate with a film containing a titanium-containing oxide or its precursor substance having an average film thickness of 0.01 to 3 μm. The film is subjected to nitriding treatment by irradiation with deep ultraviolet rays or vacuum ultraviolet rays under the following conditions, whereby the coating film is exposed to visible light to have photocatalytic activity and / or
Alternatively, a method for producing a composite material having a photocatalyst film formed thereon is characterized by modifying the photocatalyst film made of titanium-containing oxynitride exhibiting hydrophilicity. 3. The surface of a substrate is coated with a film containing a titanium-containing oxide or its precursor substance having an average film thickness of 0.01 to 3 μm, and then generated by glow discharge in an atmosphere of a mixed gas of hydrogen and nitrogen. By subjecting the coating to nitriding treatment with nitrogen ions, the coating is modified into a photocatalytic coating made of titanium-containing oxynitride that exhibits photocatalytic activity and / or hydrophilicity by irradiation with visible light.
A method for producing a composite material having a photocatalytic coating formed thereon.