JPH1073942A - Electrophotographic photoreceptor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photoreceptor having an undercoat layer which has a low resistance even when the thickness is increased, and is highly resistant to environmental change, and minimized in characteristic change in long-term use by containing a resin component, metallocene compound, and an electron attractive compound in the undercoat layer. SOLUTION: For example, a negatively charged function separating type electrophotographic photoreceptor is formed of a conductive base 1, an undercoat layer 2, and a photosensitive layer 6 containing a charge generating layer 3 and a charge transport layer 4. The undercoat layer 2 contains a resin component, a metallocene compound, and an electron attractive compound. The metallocene compound used in the undercoat layer 2 is a compound formed of two or three cyclopentadienyl rings and various transition metals. The undercoat layer 2 using the electron attractive compound together with the metallocene compound has a low electric resistance, compared with an undercoat layer containing the metallocene compound alone.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photosensitive member having an undercoat layer, and more particularly to a substance constituting the undercoat layer.

[0002]

2. Description of the Related Art In a conventional electrophotographic photosensitive member having a photosensitive layer provided on a conductive substrate, a function-separated type in which a charge generating layer and a charge transporting layer are separated is mainly used. In recent years, with the advancement of electrophotographic technology, in addition to high sensitivity, high printing durability, and high environmental stability, there are no defects such as black spots, white spots, and fog. Characteristics have been required.

In general, a function-separated type electrophotographic photoreceptor is provided on a conductive substrate in the order of a charge generation layer and a charge transport layer. The charge generation layer is usually provided with a very small thickness of submicron. Because of this, very few defects in the conductive substrate,
Scratches, dirt, deposits, and the like cause non-uniform film quality in the charge generation layer, which causes image defects. In order to prevent such image defects and to prevent a charge having a polarity opposite to that of the charged charge from being injected from the conductive substrate during charging and to prevent a reduction in the charged potential, an undercoat layer is provided as an intermediate layer. Has been proposed.

[0004] As described above, the undercoat layer provides a blocking performance for preventing injection of charges of opposite polarity from the conductive substrate to the photoreceptor, and improves the adhesion between the conductive substrate and the photosensitive layer. And the aforementioned defects of the conductive substrate,
The function of covering wounds and dirt is required. Conventionally, many resin layers have been proposed for this purpose. For example, JP-A-48-47344 discloses a method of providing a 6-nylon layer, and JP-A-52-25638 discloses a method containing a solvent-soluble nylon. Japanese Patent Application Laid-Open No. 58-30757 proposes a method of providing a polyamide resin layer.

[0005]

However, since these resin layers have relatively high hygroscopicity, their resistance greatly changes due to a change in atmospheric humidity, and thus there is a disadvantage that the electrical characteristics of the photoreceptor change. To avoid this drawback, the thickness of the resin layer is limited, but the undercoat layer itself has coating defects, such as pinholes and craters, due to the non-uniformity of the conductive substrate.

As a method of preventing such defects, a method of coating a non-hygroscopic resin with a resin layer in which conductive fine powder is dispersed has been proposed. Japanese Patent Publication No. 62-42498 discloses a method in which conductive fine particles are dispersed. With resin as subbing layer, JP-B-63-198
No. 69 proposes a resin layer in which conductive titanium oxide particles are dispersed as an undercoat layer. In the resin layer in which such conductive fine particles are dispersed, coating defects are likely to occur when the dispersion coating liquid for the charge generation layer is applied due to the fine particles protruding on the surface. For this purpose, a method of further coating a low-resistance transparent resin layer has been proposed in Japanese Patent Publication Nos. 1-51183 and 1-51185. However, in the case of this method, the number of manufacturing steps of the photoconductor increases, and there is a disadvantage in cost.

To improve this, various compositions have been proposed which are uniformly dissolved in a resin used as an undercoat layer and form a low-resistance coating film. For example, Japanese Patent Application Laid-Open No. 2-59767 proposes a solution in which an organic titanium compound is dissolved in polyvinyl acetal, and Japanese Patent Application Laid-Open No. 58-93062 proposes an undercoat layer composed of an organic metal and a resin. Alkyl compounds, alkoxy compounds, metal acetylacetonates and the like are mentioned. However, the resin liquid containing such an organic metal compound is unstable, and a metal oxide is gradually deposited.

An undercoat layer formed by dissolving ferrocene in a resin as a stable organometallic compound and applying it has been proposed in JP-A-63-25661 and JP-A-64-46762. However, in order to form a sufficiently low-resistance undercoat layer using this method, the thickness of the undercoat layer is limited, and the upper limit is 2 μm. The present invention has been made in view of the above points, and its object is to
It is an object of the present invention to provide an electrophotographic photoreceptor having an undercoat layer having low resistance, high resistance to environmental changes even when the film thickness is increased, and little change in characteristics during long-term use.

[0009]

According to the present invention, there is provided an electrophotographic photoreceptor comprising an undercoat layer and a photosensitive layer on a conductive substrate, wherein the undercoat layer comprises a resin component and a metallocene compound. And an electron-withdrawing compound. The undercoat layer in which the electron-withdrawing compound is used in combination with the metallocene compound has a lower electric resistance than the undercoat layer in which the metallocene compound is used alone.

[0010]

FIG. 1 is a sectional view showing a negatively-charged function-separated type electrophotographic photosensitive member according to an embodiment of the present invention. FIG. 2 is a sectional view showing a positively-charged function-separated type electrophotographic photosensitive member according to an embodiment of the present invention.

FIG. 3 is a sectional view showing a positively charged single-layer type electrophotographic photosensitive member according to an embodiment of the present invention. 1
Is a conductive substrate, 2 is an undercoat layer, 3 is a charge generation layer, 4 is a charge transport layer, 5 is a surface protective layer, and 6 is a photosensitive layer. The metallocene compound used for the undercoat layer is a compound composed of two or three cyclopentadienyl rings and various transition metals. The transition metal is Fe, Ti, V, Cr, Mn, Co,
In the case of Ni, Mo, Ru, Lu, Ta, W, etc., the metallocene compound is represented by chemical formula (1), and in the case of Se, Y, etc., it is represented by chemical formula (2). These metallocene compounds can also be used in the form of derivatives.

Specific examples of metallocene compounds include ferrocene, magnesocene, chromocene, cobaltene, vanadocene, titanocene, nickelocene, zirconocene dichloride, vanadocene dichloride, titanocene dichloride, ferrocene acetate, ferrocene carbaldehyde, ferrocene carboxylate, and ferrocene carboxylic acid. , Ferrocene dimethanol, ferrocene dicarboxylic acid, ferrocenyl undecyl polyoxyethylene ether and the like.

[0013]

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The electron-withdrawing compound to be combined with the ferrocene compound includes aromatic compounds such as quinone compounds, benzoquinone compounds, phthalic acid, phthalic anhydride, trimellitic acid, trimellitic anhydride, pyromellitic acid, dichlorophthalic acid and hexachlorophthalic acid. Aromatic carboxylic acids or cyano compounds such as tetracyanoethylene, 7,7,8,8-tetracyanoquinodimethane are used, and these are used in an equimolar combination with the metallocene compound.

The composition obtained by the above-mentioned combination is provided on a conductive substrate. In order to give a film-forming property, it is desirable that the composition is dissolved in a binder solution for dissolving them, coated, and formed into a film. Examples of the binder include condensation resins such as polyamide resin, polyester resin, polyurethane resin, polycarbonate resin and epoxy resin, vinyl chloride resin, acrylic resin, polyvinyl ketal resin, phenol resin, urea resin, melamine resin, guanamine resin, A curable resin such as a furan resin is used.

The amount of the metallocene compound contained in the binder depends on the required properties of the undercoat layer, but is added in an amount of 0.1 to 50% by weight based on the binder. The undercoat layer has a thickness of 0.1 to 20 μm, preferably 2 to 10 μm. The photoreceptor having the undercoat layer provided with such a composition has a small change in the external environment, particularly, a low potential change in low-temperature, low-humidity, high-temperature, and high-humidity, and an electrophotographic photoreceptor having a stable image can be obtained.

[0017]

【Example】

Example 1 A melamine resin (trade name: Uban 2020, Mitsui Toatsu Chemicals Co., Ltd.) was used as an undercoat layer on an aluminum conductive substrate having an outer diameter of 30 mm, a length of 255 mm, and a maximum height Rmax having a surface roughness of 3.0 μm. 5 parts by weight of 50 parts by weight of methanol,
Dissolved in a mixed solution of 50 parts by weight of methylene chloride and mixed with titanium oxide (trade name: P-25, manufactured by Nippon Aerosil Co., Ltd.)
A solution prepared by adding 6 parts by weight, 3 parts by weight of ferrocene and 3 parts by weight of trimellitic acid, and dispersing with a horizontal sand mill (trade name: Dyno Mill, manufactured by Shinmaru Enterprises Co., Ltd.) for 2 hours, applying the solution at 120 ° C. Dry for 15 minutes
An undercoat layer of 10 μm was provided.

Next, 10 parts by weight of an X-type metal-free phthalocyanine represented by the chemical formula (3), 10 parts by weight of a polyvinyl butyral resin (trade name: ESLEC BM-2, manufactured by Sekisui Chemical Co., Ltd.) and cyclohexanone 10 as charge generating substances
0 parts by weight was subjected to a dispersion treatment for 7 hours by a sand grinder using 0.25 mm zirconia balls as a spherical fine grinding medium. This dispersion was diluted by adding 500 parts by weight of tetrahydrofuran, dip-coated on the undercoat layer, and then heated to a temperature of 10%.
Drying was performed at 0 ° C. for 30 minutes to form a charge generation layer having a thickness of 0.3 μm.

[0019]

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Next, as a charge transporting substance, 3 parts by weight of the compound represented by the chemical formula (4), 7 parts by weight of the compound represented by the chemical formula (5), and polycarbonate (trade name: PCZ-300, molecular weight) as a binder resin 30000, manufactured by Mitsubishi Gas Chemical Co., Ltd.) and 10 parts by weight of dibutylhydroxytoluene (BHT) were dissolved in 90 parts by weight of methylene chloride.
Drying was performed at 30 ° C. for 30 minutes to provide a charge transport layer having a thickness of 20 μm. Thus, a laminated electrophotographic photosensitive drum having three layers was produced.

[0021]

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Example 2 Example 1 except that titanocene was used instead of ferrocene.
A photoreceptor was produced in the same manner as described above. Example 3 A photoconductor was prepared by the same way as that of Example 1 except that ferrocenecarboxylic acid was used instead of ferrocene. Example 4 A photoconductor was prepared by the same way as that of Example 1 except that the thickness of the undercoat layer was changed to 2 μm. Comparative Example 1 A photoconductor was prepared in the same manner as in Example 1, except that trimellitic acid was not used. Comparative Example 2 A photoconductor was prepared in the same manner as in Example 1, except that ferrocene was not used. Comparative Example 3 A photoconductor was prepared in the same manner as in Example 1, except that ferrocene and trimellitic acid were not used.

The photoconductor characteristics of each of the obtained photoconductors were evaluated. For each liquid composition of the undercoat layer, the presence or absence of memory, the presence or absence of minute black spots, and the potential of the bright part (Vi) in a low-temperature and low-humidity environment, a high-temperature and high-humidity environment, and after long-term use (after 10,000 times) It was measured. Table 1 shows the results of Examples 1 to 4.
Table 2 shows the results of Comparative Examples 1 to 3. The photoreceptor obtained by the above-described method was evaluated by the following method.

The light portion potential (Vi) is evaluated by a photoreceptor process tester, the photoreceptor is mounted on the tester, and the peripheral speed is measured.
While rotating at 78.5 mm / s, about -600 V with a corotron
, Then left in a dark place for 5 seconds, and then wavelength 780 nm
Then, light with an irradiance of ² μW / cm ² was irradiated, and the potential after 0.2 seconds was defined as a bright portion potential (Vi). Regarding the image evaluation, the memory image and the minute black spots are explained. The electrophotographic photosensitive drum is mounted on a laser printer, charged, and
A character image is exposed in the first half of a 4-size sheet, and the entire surface is exposed in the second half to create a solid black image. An image is formed by the reversal phenomenon method and the image quality is evaluated. The residual image due to the history of exposure and non-exposure, which appears due to the difference in electrical characteristics caused by the exposure, is called memory. A fog defect generated in a white image on the entire surface is called a minute black spot. The better the image, the less the occurrence of memory and no minute black spots.

As a result, in the comparative examples shown in Table 2, memory was generated under low-temperature and low-humidity conditions, fine black spots were generated under high-temperature and high-humidity conditions, and memory and fine black spots were generated after 10,000 uses. The bright portion potential Vi increases after 10,000 uses, whereas in the embodiment shown in Table 1, neither memory nor fine black spots are generated under any environment and after 10,000 uses. The potential Vi is also stable. When Examples 1 and 4 were compared, even when the thickness of the undercoat layer was increased to 10 μm as in Example 1 (2 μm in Example 4), no increase in the light portion potential Vi was observed. It can also be seen that the characteristics are also good.

[0026]

[Table 1]

[0027]

[Table 2]

[0028]

According to the present invention, in an electrophotographic photoreceptor having an undercoat layer and a photosensitive layer on a conductive substrate, the undercoat layer contains a resin component, a metallocene compound, and an electron withdrawing compound. As a result, the resistance of the undercoat layer is reduced, the thickness of the undercoat layer can be increased, the resistance to environmental changes is high, and the electrophotographic photoreceptor with little change in characteristics during long-term use can be obtained. .

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a negatively-charged function-separated type electrophotographic photoconductor according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a positively-charged function-separated type electrophotographic photoconductor according to an embodiment of the present invention;

FIG. 3 is a cross-sectional view illustrating a positively charged single-layer type electrophotographic photoconductor according to an embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 conductive substrate 2 undercoat layer 3 charge generation layer 4 charge transport layer 5 surface protective layer 6 photosensitive layer

Claims (1)

[Claims] 1. An electrophotographic photoreceptor comprising an undercoat layer and a photosensitive layer on a conductive substrate, wherein the undercoat layer contains a resin component, a metallocene compound, and an electron-withdrawing compound. Photoconductor for electrophotography.