JP4322331B2 - Hydrophilic and hydrophobic conversion method on the surface of a photocatalytic functional material, hydrophilic / hydrophobic conversion element for using the method, and printing apparatus using the method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to the conversion of hydrophilicity and hydrophobicity on the surface of a photocatalytic functional material, wherein the surface can be converted into hydrophilicity and hydrophobicity by compounding a metal with a photocatalyst according to the wavelength of light to be irradiated. The present invention relates to a method, a hydrophilic / hydrophobic conversion element for using the method, and a printing apparatus using the method.
[0002]
[Prior art]
The photocatalyst such as titanium oxide was found to have photo-induced superhydrophilicity such that water was not repelled at all when the surface was irradiated with ultraviolet rays. The mechanism of photoinduced hydrophilization of the photocatalyst surface is currently considered as follows.
1. By irradiating the surface of the photocatalyst with light having a wavelength corresponding to energy greater than the band gap, the photocatalyst itself is reduced to form oxygen defects on the surface.
2. Moisture in the atmosphere binds to and stabilizes oxygen deficient portions on the surface of the photocatalyst.
3. A thin water layer is formed on the surface of the photocatalyst, and as a result, water is not repelled.
[0003]
The photo-induced superhydrophilization phenomenon appears in oxide semiconductors such as titanium oxide, but it requires ultraviolet light of 400 nm or less as excitation light, and hydrophilicity is not present when the surface of titanium oxide is irradiated with visible light of 400 nm or more. Does not happen. That is, the wettability of the surface of titanium oxide did not respond to visible light.
[0004]
Attempts to make the photocatalyst visible light have been repeated in the fields of water electrolysis and air purification. By compounding a metal with the photocatalyst, an impurity level is formed in the band gap of the photocatalyst, and excitation with visible light having a longer wavelength than ultraviolet light becomes possible. For example, recently, nitrogen oxide decomposition by visible light has been studied by doping titanium oxide with chromium or vanadium ions by ion implantation (catalyst, Vol.39, No.2, 1997, p.146-). 149). However, since the structure of the titanium oxide photocatalyst in this technique is powder, it is structurally difficult to evaluate the contact angle with water.
[0005]
The photocatalytic superhydrophilic technology using ultraviolet light as excitation light has been put to practical use in tiles, car side mirrors, etc. as antifouling and antifogging materials. For example, WO96 / 29375 discloses a method for photocatalytically hydrophilizing the surface of a substrate, a substrate having a superhydrophilic photocatalytic surface, and a method for producing the same. WO97 / 45502 discloses an antifouling member and an antifouling coating composition. In any case, in order to improve the antifogging and antifouling functions, studies have been made mainly on maintaining the superhydrophilic state of the surface. However, there have been no studies on materials that become hydrophobic when irradiated with light. In addition, there are no reports on materials that can convert the hydrophilicity and hydrophobicity of the surface by light irradiation, and materials that reversibly switch the hydrophilicity and hydrophobicity of the surface in a short time can be applied to patterning technology such as printing equipment. It was desired as an application of.
[0006]
[Problems to be solved by the invention]
The present invention has been made in view of the above-mentioned facts, and its object is to provide a photocatalytic functional material capable of reversibly switching the hydrophilicity and hydrophobicity of the surface depending on the irradiation wavelength of light, and the photocatalytic function. It is to provide a printing device provided with a material.
[0007]
[Means for Solving the Problems]
The photocatalytic functional material according to claim 1 of the present invention is a composite of titanium oxide and at least one metal selected from the group consisting of chromium, vanadium, niobium, iron, copper, cobalt, nickel, and manganese by ion implantation. Thus, hydrophilicity and hydrophobicity conversion on the surface is possible depending on the wavelength of light to be irradiated. A printing apparatus according to claim 3 of the present invention is characterized in that the photocatalytic functional material is used.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Functional coating according to the present invention, include titanium oxide, chromium, vanadium, niobium, iron, copper, cobalt, nickel, at least one kind of metal selected from the group consisting of manganese those composite by ion implantation It becomes .
[0009]
As the titanium oxide synthesis method, for example, at least one selected from the group consisting of a CVD method, a thermal CVD method, a sputtering method, a sol-gel method, firing of a powder compact, and a vacuum deposition method is used. When titanium oxide has a film structure, the thickness of titanium oxide is preferably 20 nm or more. In any case, the titanium oxide is preferably dense enough to prevent moisture from penetrating the surface.
[0010]
At least one metal selected from the group consisting of chromium, vanadium, niobium, iron, copper, cobalt, nickel, and manganese is combined with titanium oxide by an ion implantation method. At this time, the acceleration voltage for ion implantation is preferably in the range of 50 keV to 2 MeV.
[0011]
As a light source used for photoexcitation, a lamp using at least one selected from the group consisting of a fluorescent lamp, an incandescent lamp, a mercury lamp, a xenon lamp, a mercury-xenon lamp, a halogen lamp, a metal halide lamp, laser light, and sunlight, Alternatively, a light source in which light from the light source is guided by a low-loss fiber can be suitably used. The wavelength of the light to be irradiated is set to obtain a desired wavelength by blocking unnecessary wavelengths among the light irradiated from the light source using a color glass filter, a spectroscope, or the like. Surprisingly, a very characteristic element that can be hydrophilized by irradiating the surface of the photocatalytic functional material with ultraviolet light, hydrophobized by irradiating visible light, and repeatedly inducing this phenomenon. Obtainable. As a result, the wavelength range of light required for hydrophilization was 400 nm or less, and the wavelength range of light required for hydrophobization was 430 nm to 800 nm.
[0012]
The mechanism by which the photocatalytic functional material becomes hydrophilic upon irradiation with ultraviolet light is considered as follows.
1. By irradiating the surface of the photocatalyst with light having a wavelength corresponding to energy greater than the band gap, the photocatalyst itself is reduced to form oxygen defects on the surface.
2. Moisture in the atmosphere is bonded to the oxygen defect portion and stabilized.
3. A thin water layer is formed on the surface of the photocatalyst, and as a result, water is not repelled.
On the other hand, the mechanism of hydrophobization by visible light irradiation is that the metal complexed with the photocatalyst generates an impurity level in the band gap of the photocatalyst and can be excited by visible light, and by holes, radicals, etc. generated by visible light excitation Since the surface of the photocatalyst is oxidized, it is thought that the water on the surface is desorbed as a result.
[0013]
By providing the photocatalytic functional material and a light source, a printing device is obtained. By irradiating the surface of the photocatalytic functional material with ultraviolet light and visible light, hydrophilic and hydrophobic patterning of the surface is performed. A printed material is obtained by adhering a colored material such as a hydrophilic or hydrophobic coloring matter, toner, ink, or the like to the surface by a method such as coating, spraying, or dipping, in close contact with the substrate. Since the hydrophilicity and hydrophobicity of the photocatalyst functional material reversibly change depending on the wavelength of irradiation, the printing apparatus equipped with the photocatalyst can withstand use any number of times.
[0014]
【Example】
Example 1.
A c-axis oriented anatase film was fabricated on a 1 cm square SrTiO3 substrate by CVD. Chromium ions were compounded into titanium oxide by ion implantation in the produced film. The acceleration voltage of ion implantation was 500 keV, and the implantation amount was 1016 ions / cm2. The injected film was baked in an electric furnace at 450 ° C. for 5 hours to obtain a photocatalytic functional material.
The surface of this sample was repeatedly irradiated with visible light → ultraviolet light three times, and the change in contact angle with water with respect to the irradiation time was measured. The ultraviolet light source was a 200 W mercury-xenon lamp (Hayashi Watch Industries, LA-210UV), and the wavelength was set to 360 nm through a colored glass filter (Toshiba Glass, UV-D36B).
The visible light source uses a 150W xenon lamp (Hayashi Watch Industry, LA-150Xe), and passes through an ultraviolet light cut filter (Toshiba Glass, Y-43) and a heat ray cut filter (Toshiba Glass, IRA-25S). The irradiation wavelength was set to 430 nm to 800 nm. The contact angle with water was determined by dropping water droplets from a microsyringe using a contact angle measuring device (Kyowa Interface Science, CA-X150). As a result, as shown in Fig. 1, the contact angle with water becomes hydrophilic to about 10 ° when irradiated with ultraviolet light, and it becomes hydrophobic to about 110 ° when irradiated with visible light, causing this phenomenon repeatedly. Was possible.
[0015]
Comparative Example 1
The C-axis oriented anatase film produced in Example 1 was calcined as it was (without ion implantation) in an electric furnace at 450 ° C. for 5 hours to obtain a titanium oxide photocatalyst. The surface of this sample was irradiated with ultraviolet light → visible light, and the contact angle with water with respect to the irradiation time was measured. The result is shown in FIG. When irradiated with ultraviolet rays, the contact angle with water became hydrophilic to about 0 °, and when irradiated with visible light, the contact angle became about 40 °, and the large hydrophilic → hydrophobic switching phenomenon as in Example 1 was not observed.
[0016]
【The invention's effect】
According to the present invention, the photocatalytic functional material in which at least chromium is combined with titanium oxide by the ion implantation method can convert the hydrophilicity and hydrophobicity on the surface in a short time depending on the wavelength of the irradiated light. By combining these, a printing device can be provided.
[Brief description of the drawings]
FIG. 1 shows the relationship between the contact angle between water on the sample surface and light irradiation time when ultraviolet light and visible light are repeatedly irradiated according to Example 1 of the present invention. FIG. 2 shows ultraviolet light according to Comparative Example 1 of the present invention. Relationship between contact angle with water on sample surface and light irradiation time when visible light is irradiated after light irradiation

Claims (3)

  Irradiating light to the surface of a photocatalytic functional material comprising a base material and a functional coating containing titanium oxide that is bonded to the surface of the base material and composites at least chromium by an ion implantation method, and the wavelength of the light A method for converting hydrophilicity and hydrophobicity on the surface of a photocatalytic functional material, wherein hydrophilicity and hydrophobicity conversion are performed by the method. The method for converting hydrophilicity and hydrophobicity on the surface of a photocatalytic functional material according to claim 1, wherein the conversion is made hydrophilic by irradiation with ultraviolet rays and made hydrophobic by irradiation with visible light.   A printing apparatus using the method according to claim 1, wherein the photocatalytic functional material and the surface of the photocatalytic functional material are irradiated with light, and the hydrophilicity and hydrophobicity of the surface are varied depending on the wavelength of the light. And a light source for performing sex conversion.

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