JPH02135364A - Electrophotographic composition - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a photosensitive electrophotographic composition that can be used in copying machines, printers, facsimile machines, and the like.

[Prior Art] As an image forming apparatus using a conventional photosensitive electrophotographic composition, for example, the configuration of a photoreceptor is disclosed in Japanese Patent Application Laid-Open No. 59-78358.
．． JP-A-62-50767, JP-A-57-72
There were 150. Further, when printing black toner, a three-color mixed system colored cyan, magenta, and yellow using an inorganic material such as dye-sensitized Z n Or dye-sensitized TiO2 has been used. Still another method has been to use a toner in which the above photoconductive agent is mixed with a black colorant such as carbon black. In this case, dye-sensitized ZnO is often used as the photoconductive agent. An example of a process using them is JP-A-60-3115
There was one shown in 0.

[51! [Problems to be Solved by Ming] However, the following problems have been pointed out in conventional electrophotographic compositions, and solutions are desired.

1. Organic pigments as photoconductive agents are expensive.

2. Because it is not possible to obtain a sensitizer that effectively sensitizes inexpensive 81B-free materials for electrophotography to near-infrared light, it becomes difficult to use inexpensive semiconductor lasers as light sources, which increases the cost and cost of equipment.
It leads to up.

3. The few known dyes do not have sufficient sensitivity and lack stability against semiconductor lasers due to their long methine chains.

4. When used as a toner, if carbon black is used as a black colorant, the absorption range extends from the visible to the infrared, so the photosensitivity as a photoconductive toner is significantly reduced.

5. If a three-color mixture is used as a toner, the color tone will be muddy and the toner will lack reproducibility.

6. When used as a toner, electrophotographic properties such as photosensitivity and electrical resistance of the toner may deteriorate depending on the amount of colorant added. This is particularly noticeable in a mixed system of a photoconductive agent and a black colorant.

Therefore, in the present invention, as a sensitizer, the sensitivity wavelength range is 600 nm.
m~850nm, ionization potential is 5.0e
By using a compound having a voltage of V to 9.0 eV, an electrophotographic composition having sensitivity in the near-infrared region and capable of sufficiently sensitizing a photoconductive inorganic pigment is provided, and the electrophotographic composition has excellent chargeability and The purpose is to make it possible to obtain clear images with good reproducibility while maintaining sensitivity and the like.

[Means for Solving the Problems] The electrophotographic composition of the present invention contains, as a sensitizer, a compound having a sensitivity wavelength range of 600 nm to 850 nm and an ionization potential of 5.0 eV to 9.0 eV. It is characterized by

[Function] In order for the photoconductive inorganic pigment and the sensitizer compound to interact with each other regarding charge transfer, it is necessary to match the ionization potentials of the two substances. When an inorganic pigment uses electrons as carriers, interaction requires two conditions: the electrons excited in the sensitizer by exposure to light are injected into the conduction band of the inorganic pigment, and the condition that occurs at the HOMO level of the sensitizer. Conditions are required for holes to recombine with shallow electrons in the inorganic pigment. In order to satisfy this condition and cause interaction, the ionization potential of the sensitizer must be lower than the energy level of oxygen adsorbed by the inorganic pigment. If an electrophotographic composition is prepared by adsorbing a sensitizer having the specifications of the present invention onto an inorganic pigment, a good sensitizing effect can be obtained.

Hereinafter, the present invention will be explained in detail with reference to Examples, but the present invention is not limited thereto.

[Example] The composition of the electrophotographic composition of the present invention is shown below.

It basically consists of a photoconductive agent, a binder resin, and a sensitizer, and a coloring agent is used if necessary.

The following photoconductive agents are used.

Known insulating thermoplastic resins can be used as zinc oxide, titanium oxide, zinc sulfide, selenium, cadmium sulfide, and α-silicon binder resins, and acrylic resins such as polyacrylate, polymethacrylate, etc. Polymers, polystyrene, styrene resins such as poly-1-methylstyrene and copolymers thereof, polyvinyl chloride, polyvinylidene chloride, polyvinyl fluoride, polyvinylidene fluoride, polyester resins and copolymers thereof,
Polycarbonate resin, cellulose resin, and polyarylate resin are used alone or in combination.

When coloring is required, known organic pigments and dyes are used depending on each color. For example, nigrosine, aniline blue
Calco oil blue, chrome yellow, ultramarine blue, DuPont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate, lamp black, oil black, azo oil black, rose bengal, etc.

The physical property values of the materials were evaluated using the following method.

Absorption wavelength of dye: An alcohol solution of the dye was measured using a Hitachi U-3210 spectrometer.

Ionization potential: Calculated from the photoelectron spectrum, the value almost matches the computer molecular orbital method calculation.

The electrophotographic composition of the present invention is applied to a photoreceptor or a photoconductive toner. A specific example is shown below.

[Example 1] An electrophotographic photoreceptor was produced according to the following composition.

Zinc oxide...80 parts by weight Sensitizing dye...0.08 part by weight Ethyl alcohol...160 parts by weight A cyanine dye with the following structure was used as the sensitizing dye.

The physical properties of this cyanine dye are as follows: peak sensitivity wavelength: 730n
m, and the ionization potential was 6.9 eV.

The above materials were mixed and uniformly dispersed and adsorbed using ultrasonic waves.

Next, the solvent ethyl alcohol is removed by centrifugation to obtain dried dye-adsorbed zinc oxide.

Next, the dye-adsorbed zinc oxide and the binder resin are mixed and dispersed in a solvent. As the resin, a known insulating thermoplastic resin can be used.

The following materials were dissolved in toluene solvent.

Acrylic resin: 20 parts by weight The dye-adsorbed zinc oxide described above was added to this solution, and further ultrasonically dispersed to obtain uniform dispersion in the resin to prepare a photosensitive layer forming solution.

This photosensitive layer forming solution was applied onto A1 vapor-deposited PET using a wire bar and dried in a dryer to produce an electrophotographic photoreceptor. The coating thickness after drying was adjusted to about 10 to 20 μm.

The xerographic characteristics of the electrophotographic photoreceptor produced as described above were measured using 5P-428 manufactured by Kawaguchi Electric. The light source is a halogen lamp separated by an interference filter, and light f
ilμW/cm2 was used. Measurement conditions are: s t a t L corona applied voltage -5kV
, Dark Decay 4 seconds, Light
Decay is 4 seconds, Cleaning is 2 seconds. As a result of the measurement, the charging potential was V@700V.

Half exposure, flE+/210arg/cm2. The residual potential ■R was about Ov. This shows that the cyanine dye used as a sensitizer interacts well with zinc oxide.

Further, even after repeating the durability test of charging and light irradiation 1000 times, there was no particular change in the characteristics.

[Example 2] A photoconductive toner was produced using the electrophotographic composition according to the present invention by the following manufacturing method.

Zinc oxide...40 parts by weight Sensitizing dye...0.04 parts by weight Ethyl alcohol...80 parts by weight The sensitizing dye was the same as in Example 1.

The above materials were mixed and uniformly dispersed and adsorbed using ultrasonic waves.

Next, the solvent ethyl alcohol is removed by centrifugation to obtain dried dye-adsorbed zinc oxide.

Next, a colored resin solution is prepared. As the resin used for the photoner, a known insulating thermoplastic resin can be used.

The following materials were dissolved and made compatible in an acetone solvent.

Acrylic resin...40 parts by weight Black dye-1...20 parts by weight Black dye-1 has the basic structure as shown in Figure 2, and has a benzene ring and an azo coupling, and as Me (, r
, Xi, and X3 were long-chain methyl groups, and X2゜x4 was an ethyl group.

The above-mentioned dye-adsorbed zinc oxide is added to this solution, and further subjected to ultrasonic dispersion so that it is uniformly dispersed in the resin. In this manner, the raw material solution was prepared to have a solid content of 5%, and a photoconductive toner (hereinafter referred to as photoner) having a thickness of about 10 μm was prepared by spray drying.

Next, FIG. 1 shows an outline of a process using the image forming apparatus of the present invention. The basic structure consists of a drum, a two-component developer, a writing optical system, a corona transfer device, a heat roll, and a cleaning brush. Further, the drum surface is formed of a current reader, and the inner conductive substrate is grounded.

Next, the process will be explained. While a developing electric field is being applied by the two-component magnetic brush, only the conductive toner, which is irradiated with light by the exposure system 2 to form an image, is injected with charge and further adhered to the dielectric surface. Since zinc oxide is sensitized to near-infrared rays using a sensitizing dye, an inexpensive semiconductor laser can be used as the light source. Next, the conductive phototoner is transferred to the corona charger 1.
2 to recover the resistance and pass the plain paper through the corona transfer device 6.
An image is formed on paper using normal electrostatic transfer. By passing this through a heat roll 7, it is permanently fixed. The toner remaining on the drum is collected by the cleaning brush 8.

When an image was actually formed through this process, 300
A printing speed of 20 PPM was obtained at the DPI resolution. For the black solid image, O and D values of 1°5 or more were ensured. In addition, good images were obtained with good reproducibility in 10,000 printing tests. In this method, development and exposure are performed simultaneously, increasing speed, and since only one layer is developed by charge injection, it is possible to print with clear images without background smearing. This indicates that the toner of this example functions as designed in terms of photoresponsiveness as a photoconductive toner, fixability on plain paper as a toner, and black printing temperature [Example 3] As a sensitizing dye, A phototoner was prepared using a compound having the ionization potential shown in Table 1. The composition, manufacturing method, and printing process are the same as in Example 2.

As is clear from this table, those with physical property values of ionization potential in the range of 5.0 eV to 9.0 eV showed good sensitivity and print density, and no sensitizing effect was observed in other cases.

[Example 4] An electrophotographic photoreceptor was prepared using the dye of Example 3. The composition and manufacturing method of the photoreceptor were the same as in Example 1. When this photoreceptor was evaluated in the same manner as in Example 1, it showed good xerographic characteristics.

Although the embodiments have been described above, the process using the electrophotographic composition of the present invention is applicable not only to the above embodiments but also to all processes that utilize a light source in the near-infrared region.

[Effects of the Invention] As described above, according to the present invention, an electrophotographic composition comprising an acidic dye as a sensitizer having a photosensitivity wavelength range of 600 nm to 850 nm and an ionization potential of 5.0 eV to 9.0 eV. By doing so, it has become possible to provide an electrophotographic composition that has sensitivity in the near-infrared region and is capable of sufficiently sensitizing a photoconductive inorganic pigment.

Further, an image forming apparatus using the above electrophotographic composition,
It became possible to use inexpensive semiconductor lasers as light sources.

If an image forming apparatus using the electrophotographic composition according to the present invention is used, it is inexpensive, has sensitivity in the near-infrared region, and can produce clear images with good reproducibility while maintaining chargeability, sensitivity, etc. It has the effect of making it possible to obtain

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a process using the image forming apparatus of the present invention. FIG. 2 is a diagram showing the composition of the black dye used in the photoconductive toner of the present invention. 1. Drum 2, two-component magnetic brush developer 3, exposure system 4, photoner 6, corona transfer device 7, heat roll 8, cleaning brush 9, plain paper 10, dielectric substrate 11, conductive substrate 12, corona charger, etc. Applicant: Seiko Epson Corporation

Claims (1)

[Claims] In an electrophotographic composition comprising at least a binder resin, a photoconductive inorganic pigment, and a sensitizer, the sensitizer has a sensitivity wavelength range of 600 nm to 850 nm and an ionization potential of 5.0 eV to 9.0 eV. An electrophotographic composition comprising an acidic dye.