JP2000112077A - Image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a dye image forming method using photocatalytic oxidation which proceeds on the surface of a semiconductor. SOLUTION: An image carrier is prepared by forming a TiO2 fine particle film 2 on a glass substrate 1, and a color developing precursor 3 is applied on the TiO2 fine particle film 2. By irradiating the precursor 3 with light through a mask 4, the irradiated part develops a color by photocatalytic oxidation reaction to form an image. The TiO2 fine particle film 2 may contain sensitizing dyes which absorb visible and/or IR rays.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image forming method, and more particularly to an image forming method utilizing a photocatalytic oxidation reaction generated on a semiconductor surface.

[0002]

BACKGROUND OF THE INVENTION In recent years, attention has been paid to a photocatalytic reaction on the surface of a semiconductor such as TiO ₂ . A general commentary on this type of photocatalysis can be found in "New Trends in Solid State Photocatalyst I" Vol 29, No. 2, pp. 156-169 and "New Trends in Solid State Photocatalyst V", Vol. 30, No. 4, pp. 253-267. I have.

As an application example of the photocatalytic oxidation reaction, modification and improvement of a semiconductor surface (improvement of hydrophilicity) and decomposition of an organic compound (deodorization, antibacterial, etc.) have been studied and developed. Examples of the literature include “Industrial Materials”, Vol 45, No. 10, pages 31 to 92.

The inventor paid attention to forming an image using a photocatalytic oxidation reaction. Regarding image formation,
"Dye and chemicals" Vol. 42, No. 10, pp. 278-286, applying a photocatalytic oxidation reaction with TiO ₂ in the formation of photographic dyes, A
It has been reported that, even in the absence of g-salt, a dye film was successfully formed by light irradiation in the presence of TiO ₂ .

Accordingly, an object of the present invention is to provide a novel image forming method utilizing a photocatalytic oxidation reaction generated on a semiconductor surface. Still another object of the present invention is to make it possible to form an image by a photocatalytic oxidation reaction using visible light or infrared light in the image forming method.

[0006]

In order to achieve the above objects, the present invention provides an image forming method utilizing a photocatalytic oxidation reaction generated on a semiconductor surface, wherein a color-forming precursor which forms a color by the photocatalytic oxidation reaction is provided on the semiconductor surface. It is characterized in that the precursor is colored by irradiation with light containing image information.

As a semiconductor to be used, a simple substance or a mixture of titanium oxide can be exemplified.
As the color-forming precursor, various substances such as triphenylmethane-based leucomalachite green (green) and ethyl night blue (blue) can be used.

According to the present invention, since a photocatalytic oxidation reaction on a semiconductor surface is used, an image can be formed in a simple and safe process without using an oxidizing agent as a special chemical. It is also possible to obtain a multi-color image by superimposing precursors having various colors.
In particular, if titanium oxide is used as a semiconductor, it is harmless and easily available, and versatility is improved.

It is preferable to use highly versatile titanium oxide as the semiconductor. When a semiconductor contains a sensitizing dye that absorbs visible light and / or infrared light, an image can be formed using visible light or infrared light.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an image forming method according to the present invention will be described below with reference to the accompanying drawings.

(Basic of Image Formation) FIG. 1 shows a basic form of an image forming method according to the present invention, in which an image is experimentally formed by the inventor. As the image carrier, a carrier obtained by forming a TiO ₂ fine particle film 2 on a glass substrate 1 was used. The color forming precursor 3 is formed, for example, by adding an aqueous solution of KI to TiO ₂
The coating was performed on the fine particle film 2, and the coated surface was not dried, and ultraviolet light having a wavelength of 254 nm was irradiated through the mask 4 for 30 seconds (see FIG. 1A). By this light irradiation, the precursor (KI) 3 was oxidized and developed into a mountain-blow color, and an image was obtained. In FIG. 1 (B), the colored portion is denoted by reference numeral 3a.
Indicated by

Further, when the same light irradiation as described above was performed using ethanol / aqueous solution of leucomalachite green as the color forming precursor 3, a green image could be obtained by oxidative coloring of leucomalachite green. The progress of the oxidation reaction of the color-forming precursor depends on the band gap energy of the semiconductor used. Table 1 below shows the band gaps and energies of various semiconductors.

(Materials Usable in the Present Invention) As semiconductors, the materials shown in Table 1 below can be used. The semiconductors listed in Table 1 have known relationships between the band gap size, the wavelength of light, and the energy thereof, and other semiconductors can be used.

[0014]

[Table 1]

Next, materials that can be used as a color precursor and colors of oxidized materials thereof are listed. Ethyl knight blue (blue) Methyl capryl blue (blue) Toluene blue (purple) Diphenylamine (purple) N-methyldiphenylamine-P-sulfonic acid (purple purple) Phenylanthranilic acid (purple purple) 3,3'-dimethylnaphthidine ( (Purple red) 3,3'-dimethylnaphthidine disulfonic acid (purple red) 2,6-dichlorophenol indophenol (peach) triphenylmethane leucomalachite green (green)

[0016]

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The materials listed above are known as redox indicators, and other various oxidative coloring dyes can be used. Further, various leuco compounds, such as diphenylamine, triphenylamine, triphenylmethane, and diphenylmethane, which can develop color under oxidizing conditions, can be used as various precursors.

The above materials can be used alone or as a mixture as a precursor. The hue can be adjusted by a substituent. Further, in order to smoothly progress the photocatalytic oxidation reaction on the semiconductor surface, an electron-accepting reducing compound (for example, methyl viologen) may be interposed between the semiconductor and the semiconductor.

(Use of Sensitizing Dye) Since the semiconductor absorbs light corresponding to its band gap energy and causes a photocatalytic reaction, it is necessary to use ultraviolet rays of 388 nm even for TiO ₂ or ZnO having high versatility. There is. Therefore, by incorporating a sensitizing dye into a semiconductor, the photocatalytic oxidation reaction can proceed even with light having a wavelength corresponding to the absorption wavelength of the sensitizing dye, and an image can be formed. In particular, it is practically preferable that an image can be formed with a visible light laser.

The sensitizing dye used has a property of absorbing visible light and / or infrared light, and one or more of various organic dyes and metal complexes can be used. For example, examples of the metal complex include metal phthalocyanines such as copper phthalocyanine and titanium phthalocyanine, complexes of chlorophyll, hemin, lutesium, osmium, iron, and zinc. As organic dyes, metal-free phthalocyanines, the following chemical formulas (A), (B), (C), (D)
Etc., the following chemical formula (E),
(F), (G) and the like, merocyanine dyes, xanthene dyes such as uranine, eosin, erythrosine, rhodamine B and rose bengal, and triphenylmethane dyes such as malachite green and crystal violet.

[0021]

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[0022]

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(Example of image formation using semiconductor containing sensitizing dye) FIG. 2 shows a method of forming an image experimentally using a semiconductor containing a sensitizing dye. As an image carrier,
A glass substrate 1 on which a TiO ₂ fine particle film 2 containing eosin Y having a maximum absorption characteristic of 518 nm was formed was used. The coloring precursor 3 used was one coated with ethyl night blue. When the laser diode 5 was irradiated with laser light whose upper limit wavelength was cut at 450 nm, a blue image could be obtained by the oxidative coloring of ethyl nitrite blue.

(First Example of Image Formation) As shown in FIG. 3A, while a drum 10 having a semiconductor fine particle film formed on the outer peripheral surface is rotated in the direction of arrow a, the color developing precursor is applied from the tank 11 to the outer peripheral surface. The body is supplied to form the precursor layer 3. When the precursor layer 3 is irradiated with light, the irradiated portion develops color by a photocatalytic oxidation reaction, and an image is formed. On the other hand, a sheet (for example, plain paper) 15 is conveyed in the direction of arrow b in synchronization with the rotation of the drum 10, and the precursor layer 3 on which an image is formed is transferred onto the sheet 15 (see FIG. 3B). .

Next, the protective layer 21 is applied onto the precursor layer 3 from the roller 20 rotating in the direction of the arrow a while conveying the sheet 15 in the direction of the arrow b (see FIG. 3C). Protective layer 21
Is made of, for example, polyethylene or an ethylene-acrylic acid copolymer, and is supplied from the tank 22 onto the roller 20.

By repeating the exposure and transfer steps shown in FIGS. 3A and 3B, precursor layers 3 of different colors
5, a multi-color image can be formed.

(Second Example of Image Formation) This second example uses a precursor which is formed in a film shape in advance. That is, FIG.
As shown in FIG. 1A, the color precursor film 3 is wound around the outer peripheral surface while rotating the drum 10 having the semiconductor fine particle film formed on the outer peripheral surface in the direction of arrow a. When light is applied to the wound precursor film 3, the irradiated portion develops color by a photocatalytic oxidation reaction, and an image is formed. On the other hand, in synchronization with the rotation of the drum 10, the sheet (for example, plain paper) 15 is
The precursor film 3 on which the image is formed is transferred onto the sheet 15 (see FIG. 4B).

Thereafter, the fixing step of applying a protective layer is shown in FIG.
(C) is the same as in the first example in that a multicolor image can be formed by superimposing precursor films 3 of different colors on one sheet 15.

(Other Embodiments) The image forming method according to the present invention is not limited to the above embodiment, but can be variously modified within the scope of the gist. In particular, various methods other than the first and second examples can be adopted for the method of causing the precursor to exist on the semiconductor, the exposure step, the transfer step, and the fixing step.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a basic mode of an image forming method according to the present invention.

FIG. 2 is an explanatory view showing another embodiment of the image forming method according to the present invention.

FIG. 3 is an explanatory view showing a first example of an image forming method according to the present invention.

FIG. 4 is an explanatory view showing a second example of the image forming method according to the present invention.

[Explanation of symbols]

1 ... glass substrate 2 ... TiO ₂ fine particle layer 3 ... color precursor 4 ... Mask 5 ... laser diode 10 ... drum 15 ... Sheet

Claims (5)

[Claims] 1. An image forming method using a photocatalytic oxidation reaction generated on a semiconductor surface, wherein a color-forming precursor that develops a color by the photocatalytic oxidation reaction is present on the semiconductor surface, and the precursor is irradiated by light with image information. An image forming method characterized by coloring. 2. A color precursor is applied to the surface of a semiconductor while rotating a drum body provided with a semiconductor on an outer peripheral surface, and the precursor is colored by light irradiation with image information, and the colored precursor is applied to a sheet. 2. The method according to claim 1, wherein the image is transferred onto the upper surface.
The image forming method as described in the above. 3. A color developing precursor film is wound around the surface of the semiconductor while rotating a drum body provided with a semiconductor on the outer peripheral surface, and the precursor is colored by light irradiation with image information, and the colored precursor film is formed. 2. The image forming method according to claim 1, wherein the image is transferred onto a sheet. 4. The image forming method according to claim 1, wherein the semiconductor is a single substance or a mixture of titanium oxide. 5. The semiconductor device according to claim 1, wherein the semiconductor contains a sensitizing dye that absorbs visible light and / or infrared light. Image forming method.