JPH0572761A - Production of electrophotographic sensitive - Google Patents

Abstract

PURPOSE:To improve photosensitive characteristics, especially the sensitivity characteristic of an electrophotographic sensitive material for various recording instruments which use an electrophotographic method including such processes of electrification, exposure, development and the like. CONSTITUTION:A solvent containing halogen is used as a solvent for a coating liquid of an org. photosensitive material. The prepared soln. is applied on a substrate by dipping and then subjected to heat treatment to obtain the org. photosensitive material. Thereby, the org. photosensitive material having high sensitivity and high performances can be easily realized for positively electrified monolayer OPC, negatively electrified two-layer OPC, and positively electrified reverse layer OPC.

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 an electrophotographic photosensitive member used in an electrophotographic system including processes such as charging, exposure and development.

[0002]

2. Description of the Related Art In an electrophotographic photoreceptor using a photoconductive substance as a photosensitive material, examples of the photoconductive substance include inorganic photoconductors such as selenium, zinc oxide, titanium oxide, cadmium sulfide, and amorphous silicon, and phthalocyanine. Organic photoconductors such as pigments and disazo pigments are known, and a layer containing these photoconductors is formed on a conductive support to obtain an electrophotographic photoreceptor.

Among these electrophotographic photoconductors, those having an inorganic photoconductor are not necessarily satisfactory in properties such as thermal stability and durability, and further have toxicity and therefore are not suitable for production and handling. There was also a problem.

On the other hand, an organic photoconductor (abbreviated as OPC) is capable of synthesizing a material having high sensitivity to various wavelengths by molecular design as compared with an inorganic photoconductor, is non-polluting, is excellent in productivity, is economical, and is inexpensive. It has such characteristics as, and active research and development is currently being conducted. The OPC is generally a charge generation layer (abbreviated as CGL) that absorbs light to generate carriers and a charge transfer layer (CT that moves the generated carriers).
It is used in a double layer structure (abbreviated as L), and its sensitivity is being improved.

Further, the durability and the sensitivity, which have hitherto been problems of the organic photoconductor, have been remarkably improved, and some of them have been put into practical use, and are now the main force of the electrophotographic photoconductor. ing.

In general, in an organic photoreceptor having a double-layer structure, CGL is applied in a thickness of several microns, while CTL is applied in a thickness of several tens of microns in order to improve sensitivity. At this time, because of its strength, printing durability, etc., CGL should be placed on the substrate side.
The CTL is usually formed on the front surface side. In such a structure, only the CTM that operates by the movement of holes is put into practical use, so that the double-layered photosensitive member is of the negative charging type. However, in such a negative charging method, (1) oxygen in the air becomes ozone due to the negative charge used for charging, (2) charging is unstable, and (3) thin CGL affects the drum surface. There was a problem that it was easy to receive.

In order to solve such problems, a lot of organic photoconductors by the positive charging method are now under development. Conventionally, in order to realize positive charging, (1) CGL and C
Inverse two-layer structure OPC in which TL has a reverse configuration to that in the case of negative charging,
(2) A single layer structure OPC in which various CGM and CTM are dispersed in a binder polymer, and (3) a single layer type OPC in which copper phthalocyanine is dispersed in a polymer have been studied.

In the inverse two-layer structure of the method (1), the problems of the manufacturing process and delamination, which are the same as in the case of the negative charging method, cannot be solved. Furthermore, since the CGL, which essentially needs to be thinned, is placed on the surface of the photoconductor, the print resistance due to mechanical fatigue such as abrasion has become a problem, and none has been put to practical use.

On the other hand, in the case of the single-layer type positive charging photoreceptor according to the methods (2) and (3), the sensitivity, the residual potential and the charging characteristics are different from those of the multi-layer negative charging method and the reverse layer positive charging method. Was inferior in.

However, we have investigated positively charged single-layer type organic photoconductors having various constitutions, and as a result, we have used X-type phthalocyanine or τ-type phthalocyanine as CGM, and from the combination of this and an appropriate binder polymer. It has been discovered that the single-layer organic photoreceptor having the above-described structure exhibits excellent photosensitivity in the positive charging system (Japanese Patent Laid-Open No. 3-65699). The sensitivity reaches 1.0 to 2.0 lux.sec, which is significantly higher than that of the conventional single-layer OPC. The OPC of the invention
Has excellent sensitivity to light in a wide wavelength range of 550 to 800 nm, and has very excellent light resistance and heat resistance.

[0011]

However, the recording devices in which the various organic photoconductors mentioned above are put into practical use are called low-speed machines and medium-speed machines of 10 to 30 sheets / min. In the current information-oriented society, it is strongly desired to downsize these low- and medium-speed machines and popularize them. Miniaturization of copiers, fax machines, etc. has led to miniaturization of photosensitive drums and faster drum rotation speeds. Therefore, high sensitivity has become an important issue for organic photoreceptors. ..

In addition, in a high-speed machine of 50 sheets / minute or more, an inorganic photoconductor is currently the mainstream from the viewpoint of printing durability and sensitivity, but OPC is also required to have high sensitivity in order to support these recording devices. It is an issue that cannot be done.

As a method for solving the problem, studies have been conducted to improve the charge generation efficiency by the molecular design of CGM and to improve the charge transfer rate by the molecular design of CTM.

An object of the present invention is to solve the above-mentioned problems desired for organic photoconductors by a method for producing a photoconductor and provide a high-performance and high-sensitivity organic photoconductor.

[0015]

[Means for Solving the Problems] Various investigations aimed at increasing the sensitivity of the above-described positively charged single-layer type organic photoconductor developed by the present applicant were conducted. As a result, it was found that the solvent used had a great influence on the photosensitive characteristics, particularly on the sensitivity characteristics. This is because the solvent is greatly involved in the interaction between the photosensitive material (especially phthalocyanine type) and the binder resin in the process of dispersing or kneading, and the solvent does not remain in the photoreceptor after the dry heat treatment. I don't think so.

Therefore, various investigations have been made from the viewpoint of whether or not the solvent to be used has a specific group, and by using a solvent containing halogen as the solvent, a positively charged organic photoreceptor having high sensitivity and high performance is realized. Came to.

Among the halogens, a solvent containing chlorine is particularly preferable, and examples of the solvent containing chlorine include methylene chloride, 1,1-dichloroethane, chloroform, monochlorobenzene, dichlorobenzene and the like.

[0018]

By using the production method according to the present invention, the production of the negatively charged two-layer type OPC and the reverse layer type positively charged OPC described above is also examined, and the same high performance as our positively charged OPC is obtained. It has been possible to realize an organic photoconductor that is stable and has high sensitivity.

[0019]

EXAMPLES Next, examples of the present invention will be described in more detail. Needless to say, the present invention is not limited to the following embodiments.

(Example 1) X-type metal-free phthalocyanine (abbreviated as XPc, manufactured by Dainippon Ink and Chemicals) and FOC-10 (Fuji Yakuhin Co., Ltd.) having a structure as shown in the following (Chemical formula 1)
Made) and

[0021]

[Chemical 1]

Naphthoic acid in methylene chloride 10:10:
After being dissolved in 1 and dispersed and mixed by a ball mill method, the resulting solution is applied on an aluminum plate by a dip method, heat-treated in air at 150 ° C. for 2 hours, and heat-cured to obtain C.
GL (thickness 1 μm) was formed. Next, the charge transfer layer (C
TL) as a CT material, CTC-236 (manufactured by Anan Fragrance),
As a binder resin, Byron 200 (Toyobo Co., Ltd.)
Was used to form a negatively charged two-layer type OPC by using tetrahydrofuran as a solvent to form a film having a thickness of 15 μm.

As Comparative Example 1, a similar photoreceptor was prepared except that tetrahydrofuran was used as the solvent for the CGL coating solution.

The photosensitivity of the thus obtained photoconductor was measured by using a paper analyzer made by Kawaguchi Denki Co., Ltd., EPA-8100, and white light of tungsten was applied to the photosensitivity (half exposure amount, E1 / 2) The residual potential Vr was measured, and the photosensitivity after 10,000 repeated tests was also measured. The results are shown in (Table 1). As is clear from (Table 1), it is understood that the photosensitivity in the initial characteristics of Example 1 is remarkably improved as compared with Comparative Example 1.

[0025]

[Table 1]

Example 2 As Example 2, X-type metal-free phthalocyanine (abbreviated as XPc, Dainippon Ink and Chemicals, Inc.)
And Byron 290 (manufactured by Toyobo Co., Ltd.) were mixed and kneaded in methylene chloride at a ratio of 1: 4, and the resulting solution was applied on an aluminum plate to a thickness of 25 μm by a dip method and air Heat treatment was carried out at 150 ° C. for 2 hours to form a positively charged single layer type photoreceptor.

As Comparative Example 2, a similar photosensitive member was prepared by using tetrahydrofuran. Using the EPA-8100 type paper analyzer manufactured by Kawaguchi Electric Co., Ltd., the photosensitivity of the photoconductor thus obtained was irradiated with white light from tungsten, and the photosensitivity (half-exposure amount, E1 / 2) due to positive charging remained. The potential Vr was measured, and the photosensitivity after 20,000 times of repeated tests was measured in the same manner. The results are shown in (Table 2).
It can be seen that the photosensitivity in the initial characteristics of Example 2 is remarkably improved as compared with Comparative Example 2.

[0028]

[Table 2]

Example 3 As Example 3, X-type metal-free phthalocyanine (abbreviated as XPc, Dainippon Ink and Chemicals, Inc.)
And polystyrene (Asahi Kasei Co., Ltd.) in a mixed solvent of chloroform and tetrahydrofuran (mixing ratio 1: 1) at a ratio of 1: 3, and the resulting solution is dipped on an aluminum plate. To a thickness of 20 μm and heat-treated in air at 150 ° C. for 2 hours to form a positively charged single-layer type photoreceptor. Further, as Comparative Example 3, a similar photoconductor was prepared using tetrahydrofuran.

The photosensitivity of the thus-obtained photoconductor was measured using a EPA-8100 type paper analyzer manufactured by Kawaguchi Denki Co., Ltd., by irradiating it with white light from tungsten to obtain photosensitivity (half-exposure amount, E1 / 2) The residual potential Vr was measured, and the photosensitivity after the repeated test after 10,000 times was also measured in the same manner. The results are shown in (Table 3). It can be seen that the photosensitivity in the initial characteristics of Example 3 is remarkably improved as compared with Comparative Example 3.

[0031]

[Table 3]

(Example 4) As Example 4, first, the charge transfer layer (CTL) was used as a CT material, CTC-236 (manufactured by Anan Perfume Co., Ltd.), and the binder resin, polycarbonate Z-.
200 (manufactured by Mitsubishi Gas Chemical Co., Inc.) was used, and tetrahydrofuran was used as a solvent to form a film having a thickness of 15 μm on an aluminum plate by a dipping method. Next, an X-type metal-free phthalocyanine (abbreviated as XPc, manufactured by Dainippon Ink and Chemicals, Inc.) and FOC-12 (manufactured by Fuji Yakuhin Co., Ltd.) having a structure as shown below (Chemical Formula 2) were used.

[0033]

[Chemical 2]

The solution was dissolved in chloroform at a ratio of 1: 1 and dispersed and mixed by a ball mill method. The resulting solution was coated on CTL by a dip method and heat-treated in air at 150 ° C. for 2 hours to obtain CGL. (Thickness 1 μm) was formed to prepare an inverse layer type positively charged OPC.

As Comparative Example 4, CTL was prepared in the same manner, and C
A photoconductor using cyclohexanone as a solvent for the GL coating solution was prepared.

The photosensitivity of the photoconductor thus obtained was measured using a EPA-8100 type paper analyzer manufactured by Kawaguchi Denki Co., Ltd., by irradiating it with white light from tungsten to obtain a photosensitivity (half exposure amount, E1 / E1) due to positive charging. 2) The residual potential Vr was measured, and the photosensitivity after 10,000 repeated tests was also measured. The results are shown in (Table 4). It can be seen that the photosensitivity in the initial characteristics of Example 4 is remarkably improved as compared with Comparative Example 4.

[0037]

[Table 4]

Further, in the above-mentioned Examples 1 to 4, it was confirmed that the photoconductor having the above-mentioned highly sensitive characteristics can be produced with good reproducibility.

As is clear from these results, a high-sensitivity photoconductor can be easily obtained while maintaining high performance by forming the photoconductor using the manufacturing method of the present invention.

The characteristics of this photoconductor did not change significantly even under the environment of high temperature and high humidity or low temperature and low humidity.

Further, although chlorine is used as the halogen in the above embodiment, similar results were obtained with bromobenzene, dibromobenzene and hexafluorobenzene.

[0042]

As described above, according to the present invention, by using a solvent containing a halogen as a solvent of a solution used for coating an organic photoconductor, a more sensitive electrophotographic photoconductor can be easily prepared. It is manufactured and expected to be applied to various recording devices.

Continued Front Page (72) Inventor Souji Tsuchiya 3-10-1 Higashisanda, Tama-ku, Kawasaki City, Kanagawa Prefecture Matsushita Giken Co., Ltd.

Claims (4)

[Claims] 1. A method for producing an electrophotographic photosensitive member, wherein a solvent containing halogen is used as a solvent of a solution used for coating an organic photosensitive member. 2. The method for producing an electrophotographic photosensitive member according to claim 1, wherein the halogen is chlorine. 3. A phthalocyanine is contained as a sensitizer in a coating solution of an organic photoreceptor.
A method for producing the electrophotographic photosensitive member described. 4. The electrophotographic photoconductor according to claim 1, wherein the organic photoconductor is a single-layer type comprising only a metal-free X-type phthalocyanine and a binder polymer. Manufacturing method.