JP2002210364A - Zinc oxide film having photocatalytic property and method for forming the film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a zinc oxide film having good photocatalytic properties. SOLUTION: The zinc oxide film contains 0.001-20 wt.% of boron.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a zinc oxide film having photocatalytic properties and a method for forming the same.

[0002]

2. Description of the Related Art Since titanium oxide has excellent photocatalytic properties, its application to various fields has been realized. Since zinc oxide also has a band gap of 3.3 eV, it is expected to have a photocatalytic property equivalent to that of titanium oxide. However, the zinc oxide film has many problems in maintaining the photocatalytic property due to its deterioration and the like.

An object of the present invention is to solve these problems,
An object of the present invention is to provide a zinc oxide film having excellent photocatalytic properties over a long period of time and a method for forming the same.

[0004]

Means for Solving the Problems and Embodiments of the Invention The present inventors have made intensive studies to achieve the above object, and as a result, zinc oxide containing 0.001 to 20% by weight of boron in zinc oxide. It has been found that a zinc oxide film having excellent photocatalytic properties can be obtained by performing a heat treatment on a zinc oxide film containing 0.001 to 20% by weight of boron, which has been modified with a film or a metal or a metal compound. .

That is, the zinc oxide film having photocatalytic property of the present invention contains 0.001 to 20% by weight of boron in the film, and particularly, when this film is subjected to a heat treatment, the photocatalytic property is excellent. A zinc oxide film can be obtained.

Accordingly, the present invention provides the following zinc oxide film having photocatalytic properties and a method for forming the same. Claim 1: In a zinc oxide film, boron is contained in a weight ratio of 0.0.
A zinc oxide film having photocatalytic properties, which is contained in an amount of from 0.01 to 20% by weight. Claim 2: A zinc oxide film having photocatalytic properties obtained by subjecting the film of claim 1 to a heat treatment. Claim 3: The film according to claim 1 is made of Ag, Pd, Au, P
a photocatalyst obtained by treating the surface of the zinc oxide film with the metal or a compound containing the metal by treating with an aqueous solution containing at least one metal ion selected from the group consisting of Zinc oxide film with properties. In a preferred embodiment, the ratio of the metal or the metal compound to the zinc oxide is 0.01 to 30% by weight as the metal. Claim 5: 0.001 to 20% by weight of boron by weight
A method for forming a zinc oxide film having photocatalytic properties, wherein the zinc oxide film is heat-treated. Claim 6: 0.001 to 20% by weight of boron by weight
A method for forming a photocatalytic zinc oxide film, comprising: treating a zinc oxide film contained therein with an aqueous solution containing at least one metal ion selected from Ag, Pd, Au, and Pt, followed by heat treatment.

Hereinafter, the present invention will be described in more detail.
The zinc oxide film having photocatalytic properties of the present invention forms a zinc oxide film containing a specific proportion of boron on a substrate by a method described below.
It is formed on a substrate by a wet plating method (electroless plating method or electrolytic plating method).

Here, the substrate is not particularly limited, but NESA glass, ITO glass, a metal plate, or the like can be used as the conductive substrate, and a glass substrate, plastic, ceramic, or the like can be used as the non-conductive substrate. Glass fiber, glass cloth, nonwoven fabric, natural fiber and the like can be mentioned.

When forming an electroless zinc oxide film on such a substrate, the following steps can be performed. (1) Washing: A known degreasing agent or organic solvent can be used, and the treatment can be performed under known treatment conditions. (2) Surface conditioning: A known surface conditioning agent is used to impart a charge to the substrate surface. (3) Catalyst application: A catalyst is applied to the substrate surface using a known catalyst applying agent. (4) Preparation of electroless zinc oxide film: A zinc oxide film is deposited on a substrate.

In this case, as the surface conditioner, an aqueous solution containing 1 to 50 g / L of a cationic surfactant or a cationic polymer compound as a main component can be used. The immersion treatment can be performed for 10 minutes.

The catalyst application treatment in the above step (3) includes any of the catalyst treatment steps for forming an electroless plating film, such as a sensitizing-activating method, a catalyst-accelerator method, and an alkaline catalyst method. Can be used. In particular, it is preferable to employ a sensitizing treatment with Sn-Ag activation treatment-Pd activation treatment with Sn, and when the boron in the electroless zinc oxide film described later is in a specific range, the photocatalytic property is further improved. In addition, when heating described later is applied, the zinc oxide crystallinity of the zinc oxide film or the modified zinc oxide film is more easily improved.

In the present invention, the activator used for the above-mentioned Ag activation treatment may be silver ion 0.0001 to 0.001.
It is preferably 0.5 mol / L, particularly preferably 0.001 to 0.1 mol / L.

In this case, silver ion sources such as silver sulfate, silver sulfite, silver nitrate, silver thiosulfate, silver methanesulfonate and the like can be used, but are not limited thereto. Activation performance can be improved by mixing a divalent metal ion with the solution containing silver ions as a main component.

As this example, Ni ion, Co ion, iron ion, zinc ion, copper ion and the like can be preferably used. These concentrations are the same as those of the silver ions. As the anion for the silver ion, a sulfate ion, a nitrate ion, a halogen ion, a methanesulfonate ion and the like are preferably used, but are not particularly limited. The pH is suitably about 5 to 11.

The temperature of the silver-based solution of the present invention is:
Although it can be set in a wide range, it is usually preferable to be 15 to 60 ° C. Also, the immersion time in these activators can be appropriately selected, but is preferably 10 seconds to 5 minutes, and more preferably 30 seconds to
It is preferable to perform the immersion treatment for 2 minutes.

The electroless zinc oxide film deposition solution in the step (4) is not particularly limited as long as it is a solution for depositing zinc oxide, and a zinc salt such as zinc nitrate is used in an amount of 0.01 to 0. 0.5 mol / L, preferably 0.05 to
0.2 mol / L, 0.001-0.3 mol of borane-based reducing agent such as dimethylamine borane, and other reducing agents
/ L, preferably about 0.005 to 0.1 mol / L, particularly about 0.01 to 0.05 mol / L, and a pH of about 4 to 9, particularly about 6.5, can be suitably used. A method of immersion treatment at 80 ° C. for 10 to 200 minutes can be adopted. In this case, since a borane-based reducing agent such as dimethylamine borane is used as the reducing agent, boron is eutectoid in the zinc oxide film.

In addition to the methods described above, boron is contained in the zinc oxide film by a method of eutecting boron by adding boric acid to the bath, or by immersing in a boric acid solution after forming the zinc oxide film. There is a method of displacing or adsorbing. The concentration at which boric acid is added to the bath is such that boric acid is added to the electroless zinc oxide deposition solution in an amount of 0.1 to 20 g / L, particularly
A method of adding ５5 g / L can be adopted. Further, the method of substituting or adsorbing boron after zinc oxide is formed is as follows: a solution in which boric acid is dissolved in 0.1 to 30 g / L, particularly 1 to 10 g / L, at room temperature for 10 seconds to 5 minutes, particularly 30 seconds to 2 A method of immersing for minutes may be employed.

On the other hand, when an electrolytic zinc oxide film is formed, it can be performed in the following steps. (1) Washing: A known degreasing agent or organic solvent can be used, and the treatment can be performed under known treatment conditions. (2) Preparation of electrolytic zinc oxide film: A zinc oxide film is deposited on a substrate.

In this case, the electrolytic zinc oxide film deposition solution in the step (2) is not particularly limited as long as it is a solution for depositing zinc oxide. 0.5 mol / L, preferably 0.05 to
0.2 mol / L, 0.001-0.3 mol of borane-based reducing agent such as dimethylamine borane, and other reducing agents
/ L, preferably about 0.005 to 0.1 mol / L, particularly about 0.01 to 0.05 mol / L, and a treatment liquid having a pH of about 4 to 9, particularly about 6.5 can be suitably used. A zinc oxide film can be obtained by applying a current of 0.1 to 20 coulombs, preferably 1 to 10 coulombs per cm ^{2 of the} conductive substrate using zinc, carbon, platinum or the like. The bath temperature is used in the range of 10 to 80C. In this case, boron is eutectoid in the zinc oxide film due to the presence of a borane-based reducing agent such as dimethylamine borane in the bath.
In addition, as a method of containing boron in the zinc oxide film, a method of eutecting boron by adding boric acid in a bath, and a method of substituting or adsorbing by immersing in a boric acid solution after forming the zinc oxide film Can also be adopted. The concentration of boric acid added to the bath is 0.1 to 20 g / L, particularly 1 to 5 g of boric acid in the electrolytic zinc oxide deposition solution.
A method of adding g / L can be adopted. Further, the method of substituting or adsorbing boron after the formation of zinc oxide is as follows. A method of immersing for minutes may be employed.

The thickness of the zinc oxide film is 0.001 to 0.001.
2 μm, especially 0.01-1 μm,
It is not limited to this.

[0021] The amount of boron in the zinc oxide film is 0.1%.
It is 001 to 20% by weight, preferably 0.01 to 15% by weight, and more preferably 0.1 to 10% by weight.

In the present invention, it is preferable to modify the zinc oxide film after the above steps. In this case, the zinc oxide coating modifier according to the present invention contains one or more of Ag, Pd, Au, and Pt ions. The counter anion is not particularly limited as long as it makes the metal compound water-soluble, and is not particularly limited. Sulfate ion, halogen ion, phosphate ion, nitrate ion, acetate ion, citrate ion, lactic acid Ions and other carboxylate ions. It is effective that the metal ion is contained in the aqueous solution in an amount of 0.01 to 50 g / L, more preferably 0.1 to 30 g / L.

The p of the above-mentioned metal ion-containing aqueous solution (modifier)
H is preferably 2 to 10, especially 3 to 8.

The conditions for treating the zinc oxide film with the modifier of the present invention are appropriately selected, but are preferably 10 to 60 ° C., particularly 20 to 40 ° C., for 1 second to 10 minutes, particularly 5 seconds to 5 minutes. The treatment can be carried out in a matter of minutes, and the treatment can be carried out by immersing the zinc oxide film in a modifier, but may be carried out by spray treatment or the like. As a result, the surface of the zinc oxide film is modified by the metal or a compound containing the metal (mainly, an oxide of the metal, an alloy of the metal and zinc, particularly a metal oxide). The ratio of the metal and the metal compound to the zinc oxide in the zinc oxide film is preferably 0.01 to 30% by weight as the metal.

The present invention is a zinc oxide film having photocatalytic properties produced by subjecting the above zinc oxide or modified zinc oxide to a heat treatment.

The heat treatment is performed at 150 to 700 ° C., preferably 200 to 650 ° C., and more preferably 400 to 60 ° C.
It is recommended to carry out at 0 ° C., and the heating time is preferably 5 minutes to 2 hours, particularly preferably 10 minutes to 1 hour.

Further, the heating atmosphere may be any one of an atmosphere, a non-oxidizing gas atmosphere such as nitrogen, helium, and argon, a reducing gas atmosphere such as hydrogen, and a mixed gas atmosphere thereof.

According to the present invention, a zinc oxide film having excellent photocatalytic properties can be obtained by the above steps. In this case, it is not clear why the zinc oxide film having excellent photocatalytic properties was obtained, but the heat treatment activated boron in the zinc oxide film, and the interaction between the activated boron and zinc oxide. It is thought that the photocatalytic property was improved by improving the crystallinity of zinc oxide. Here, the content of boron contained in the zinc oxide film is, as described above, 0.001 to 20% by weight,
Especially 0.01 to 15% by weight, more preferably 0.1 to 10% by weight
It is preferred that When the content of boron contained in the zinc oxide film is less than 0.001% by weight, the effect of adding boron is weakened, and the photocatalytic property is reduced. Is reduced.

The photocatalytic zinc oxide film of the present invention contains boron in the zinc oxide film, and after dissolving the zinc oxide film obtained by the above method, an ICP (inductively coupled plasma emission spectrometer) is used. ), The elemental analysis of the surface confirmed that the zinc oxide film contained boron.

With respect to the photocatalytic activity of the obtained zinc oxide film, the activity against decomposition of acetaldehyde gas upon irradiation with a Xe lamp was evaluated. It was found that the acetaldehyde gas having an initial concentration of 50 ppm was decomposed to 1 ppm or less after 5 minutes. confirmed.

Therefore, the zinc oxide film of the present invention is excellent in photocatalytic properties, and therefore, for example, large substrates such as window glasses used for vehicles, buildings, buildings, airplanes, etc., fluorescent lamps, fluorescent lamp peripheral parts, curtains, etc. It can also be used for glass fiber or glass cloth, non-woven fabric, natural fiber, and the like used for clothing and clothing.

Further, may be formed of TiO ₂ on the zinc oxide film can be obtained as described above, in the above step onto the TiO ₂ may be formed of zinc oxide film.

In this case, the titanium oxide layer is preferably formed of anatase type titanium oxide. The titanium oxide layer has a photocatalytic function and has transparency. Preferably, the thickness of the titanium oxide layer is between about 1,000 and 5,000 angstroms. In producing the above-mentioned photocatalytic transparent film, a TiO ₂ layer can be formed by a coating method or a vacuum evaporation method.

In the case of forming such a multilayer structure, it is preferable to perform a heat treatment.

The heat treatment is performed at 150 to 700 ° C., preferably 200 to 650 ° C., and more preferably 300 to 60 ° C.
It is recommended to carry out at 0 ° C., and the heating time is preferably 5 minutes to 2 hours, particularly preferably 10 minutes to 1 hour.

Further, the heating atmosphere may be any one of an air atmosphere, a non-oxidizing gas atmosphere such as nitrogen, helium, and argon, a reducing gas atmosphere such as hydrogen, and a mixed gas atmosphere thereof.

According to the present invention, the above zinc oxide film and Ti
By forming a film having an O ₂ film, the photocatalytic property is improved.

[0038]

According to the present invention, a zinc oxide film having excellent photocatalytic properties can be formed.

[0039]

EXAMPLES The present invention will be described below in detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

Examples 1 to 5 Using soda lime glass as a non-conductive substrate, washing with a commercially available degreasing agent, immersing in the following surface conditioner at 50 ° C. for 5 minutes, washing with water, and then washing After sensitizing with a sensitizing solution described below at 20 ° C. for 1 minute, activation treatment was performed with a silver activating solution at 20 ° C. for 1 minute, and further with a palladium activating solution at 20 ° C. for 1 minute.

Next, the substrate was immersed in an electroless zinc oxide deposition solution having different concentrations of DMAB (dimethylamine borane) at 65 ° C. for 30 minutes to deposit zinc oxide films having different boron contents on the substrate by an electroless method. Was. Degreasing agent Asahi Cleaner C-4000 manufactured by Uemura Kogyo Co., Ltd. 5 g / L Surface conditioner Sulcup CD-202 manufactured by Uemura Kogyo Co., Ltd. 50 mL / L Sensitizing solution Sensitizer S-10X manufactured by Uemura Kogyo Co., Ltd. 100 mL / L silver activated Solution AgNO ₃ 1.5 g / L NiSO ₄ .6H ₂ O 0.3 g / L pH 7 palladium activation solution Activator A-10X 100 mL / L electroless zinc oxide plating solution manufactured by Uemura Kogyo Co., Ltd. Example 1: Zn ( _{NO 3) 2 · 6H 2 O} 30g / L dimethylamine borane 10 g / L example _{2: Zn (NO 3) 2} · 6H 2 O 30g / L dimethylamine borane 5 g / L example _3: Zn (NO 3) ₂ · 6H ₂ O 30g / L dimethylamine borane 1 g / L example _{4: Zn (NO 3) 2} · 6H 2 O 30g / L dimethylaminopyridine Borane 0.5 g / L Example 5: Zn (NO ₃₎ content of ₂ · 6H ₂ O 30g / L dimethylamine borane 0.1 g / L boron in zinc oxide, calculated by the measurement by ICP after dissolving the coating did.

[Examples 6 to 10] The films obtained in Example 3 were exposed to air at 250 ° C., 350 ° C., and 4 ° C., respectively.
Heat treatment was performed at 50 ° C., 550 ° C., and 650 ° C. for 10 minutes to obtain modified zinc oxide films of Examples 5 to 8.

[Examples 11 to 22] With respect to the film obtained in Example 3, after forming a zinc oxide film, the film was immersed in a zinc oxide modifier shown in Table 1 at 30 ° C. for 30 seconds to 10 minutes, respectively. Heat treatment at 550 ° C. for 10 minutes to form a modified zinc oxide film (Examples 11 to 13: modification with Ag, Examples 14 to 1)
6: reforming with Au, Examples 17 to 19: reforming with Pd, Examples 20 to 22: reforming with Pt).

[0044]

[Table 1]

Comparative Example 1 A zinc oxide film was obtained in the same manner as in the example using the following electroless zinc oxide plating solution. Electroless zinc oxide plating solution Comparative Example 1: Zn (NO ₃ ) ₂ .6H ₂ O 30 g / L Dimethylamine borane 20 g / L

With respect to the photocatalytic activity of the zinc oxide films obtained in Examples 1 to 22 and Comparative Example 1, the activity for decomposing acetaldehyde gas upon irradiation with a Xe lamp was evaluated.

In the test, a cell using quartz glass was used, and acetaldehyde gas was adjusted so as to have an initial concentration of 50 ppm. After that, the cell was irradiated with a Xe lamp for 5 minutes, and the concentration of acetaldehyde gas in the cell was determined by gas chromatography. analyzed. Table 2 shows the decomposition rate of acetaldehyde gas with respect to the initial concentration.

[0048]

[Table 2]

From the above results, it is confirmed that the zinc oxide of the present invention is a film having excellent photocatalytic properties.

Continued on the front page F-term (reference) 4G069 AA03 AA08 BA14A BA14B BA48A BB02A BB02B BB04A BB04B BC32A BC32B BC33A BC33B BC35A BC35B BC72A BC72B BC75A BC75B BD03A BD03B CA10 CA17 EA07 EA11 FB08

Claims (6)

[Claims] 1. A photocatalytic zinc oxide film, characterized in that the zinc oxide film contains 0.001 to 20% by weight of boron by weight. 2. A zinc oxide film having photocatalytic properties, which is obtained by heat-treating the film according to claim 1. 3. The coating according to claim 1, wherein said coating is Ag, Pd, A
the zinc oxide film surface is treated with an aqueous solution containing at least one metal ion selected from u and Pt to modify the surface of the zinc oxide film with the metal or a compound containing the metal, and then heat-treated. Zinc oxide film with photocatalytic properties. 4. The method according to claim 3, wherein the ratio of the metal or the metal compound to the zinc oxide is 0.01 to 30% by weight as the metal.
A zinc oxide film having the photocatalytic property described above. 5. A method for forming a zinc oxide film having photocatalytic properties, comprising heating a zinc oxide film containing 0.001 to 20% by weight of boron by weight. 6. A zinc oxide film containing 0.001 to 20% by weight of boron by weight is treated with an aqueous solution containing at least one metal ion selected from Ag, Pd, Au and Pt, and then heated. A method for forming a zinc oxide film having photocatalytic properties, comprising: