JPH0435747B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a laminated organic photoreceptor, and more specifically, it comprises a subbing layer, a charge generation layer, and a charge generation layer on an electrically conductive support, and is particularly sensitive to the wavelength of a semiconductor laser. The present invention relates to a laminated organic photoreceptor that can be suitably used as a photoreceptor for laser beam printers. Conventional technology In recent years, Japanese Patent Publication No. 55-42380 and Japanese Patent Publication No. 1983
As described in Publication No. 34099, an electrophotographic device is a multilayer type in which a charge generation layer containing a charge generation substance and a charge transport layer containing a charge transport substance are stacked on a conductive support. Organic photoreceptors have been developed and put into practical use. Such a laminated organic photoreceptor is, for example,
A charge generation layer and a charge transport layer are laminated in this order on a conductive support made of aluminum. In these laminated organic photoreceptors, the charge generation layer is formed by forming a dispersion of a charge generation substance together with an appropriate organic solvent, a binder, and, if necessary, a plasticizer, etc., and applying this to a conductive support. It is prepared by coating, drying, and forming a thin film. In addition, the charge transport layer is formed by dissolving a charge transport substance in a solvent together with a binder and, if necessary, a plasticizer, etc., coating the solution on the charge generation layer, and drying it to form a thin film. It is then prepared. In such a laminated organic photoreceptor,
The thickness of the charge generation layer is usually increased in order to increase the charging ability of the photoreceptor in the dark and improve the photosensitivity.
It is desirable that the thickness be 1 μm or less. On the other hand, when a copy image is formed by an electrophotographic process using reversal development using such a laminated organic photoreceptor, image defects such as black spots and black streaks may occur. Conventionally, in laminated organic photoreceptors, a resin layer called an undercoat layer or an intermediate layer is laminated between the conductive support and the charge generation layer. For example, Japanese Patent Publication No. 58-45707 and Japanese Patent Application Laid-Open No. 60-168157 propose forming the undercoat layer from an alcohol-soluble polyamide resin. In this way, if an undercoat layer is provided, the charge generation layer can be made into a uniform thin film, but on the other hand, depending on the electrical properties of the undercoat layer and the charge generation substance and binder resin in the charge generation layer, The characteristics of the photoreceptor, such as charging ability, photosensitivity, and residual potential, are significantly affected, resulting in problems such as image defects not being sufficiently eliminated, or even if image defects are eliminated, residual potential increases. Therefore, various special combinations of an undercoat layer and a charge generation layer have been proposed. for example,
JP-A-58-30757 proposes a photoreceptor in which an undercoat layer is formed from an alcohol-soluble polyamide resin and polyvinyl butyral is used as a binder resin for a charge generation layer. Further, Japanese Patent Application Laid-Open No. 60-227264 proposes a photoreceptor in which an undercoat layer is formed from an alcohol-soluble polyamide resin and copper phthalocyanine is used as a charge generating substance. On the other hand, in recent years, there has been a demand for photoreceptors for laser beam printers that are sensitive to a long wavelength region around 780 nm, which is the wavelength of semiconductor lasers. However, even if the photoreceptor has an undercoat layer, for example, a photoreceptor using an azo thread pigment, which is conventionally widely known as a charge-generating substance, has low sensitivity to long wavelength light from a semiconductor laser. Although it is already known that X-type metal-free phthalocyanine is sensitive to long wavelengths of semiconductor laser light, a laminated photoreceptor that is highly sensitive to such long wavelength light has not been known so far. . For example, in Japanese Patent Publication No. 49-4338 and the corresponding US Patent No. 3816118,
In particular, a single-layer type photoreceptor using this X-type metal-free phthalocyanine has been described, but the sensitivity is low. Problems to be Solved by the Invention As a result of intensive research to obtain an organic photoreceptor that can be used as a photoreceptor for laser beam printers, the present inventors unexpectedly discovered that an alcohol-soluble polyamide resin was used as an undercoat layer. In addition, using X-type metal-free phthalocyanine as a charge generating substance,
In addition, by using vinyl chloride-ethylene copolymer as the binder resin for forming the charge generation layer, it has high charging ability in the dark and high sensitivity near 780 nm, which is the wavelength of semiconductor lasers. The inventors have discovered that it is possible to obtain a laminated organic photoreceptor that provides copied images without image defects, and have thus arrived at the present invention. Means for Solving the Problems The present invention provides a multilayer organic photoreceptor comprising an undercoat layer, a charge generation layer, and a charge transport layer on a conductive support, the undercoat layer being made of an alcohol-soluble polyamide resin, The charge generation layer contains X-type metal-free phthalocyanine as a charge generation substance and vinyl chloride as a binder.
It is characterized by containing an ethylene copolymer. In the present invention, the alcohol-soluble polyamide resin used as the undercoat layer is, for example,
These are various copolymerized nylons as described in Japanese Patent Publication No. 58-45707. Specific examples include nylon 6/66, nylon 6/66/610, nylon 6/66/610/12, and the like. Such alcohol-soluble copolymerized nylon can be obtained as a commercial product. In addition, as another specific example, N
- Like alkoxymethyl modified nylon,
Examples include those made by chemically modifying homonylon. Such alcohol-soluble nylon also includes, for example, CM-8000 manufactured by Toray Industries, Inc.
etc. can be obtained as commercial products. The above-mentioned alcohol-soluble polyamide resin is soluble in lower aliphatic alcohols such as methanol, ethanol, and propanol, and in the present invention, the alcohol-soluble polyamide resin is dissolved in such alcohol to form a solution. It is applied onto a conductive support and dried by heating to form an undercoat layer. If necessary, an aromatic hydrocarbon such as toluene or xylene can be added to the alcohol solution of the alcohol-soluble polyamide resin in order to improve the stability of the solution. Furthermore, if necessary, a small amount of water, trichloroethylene, chloroform, benzyl alcohol, phenol, formic acid, acetic acid, etc. may be added to the above solution. The thickness of the undercoat layer is usually
0.3-5 μm is suitable. In the multilayer organic photoreceptor according to the present invention, a charge generation layer is formed on the undercoat layer. In the present invention, the charge generating substance is. It is an X-type metal-free phthalocyanine and is represented by the following formula. The X-ray diffraction pattern (CuKα ray, powder method) of such X-type metal-free phthalocyanine is shown in FIG. Further, the charge generation layer is formed using a vinyl chloride-ethylene copolymer as a binder resin. As a vinyl chloride-ethylene copolymer, for example, an ethylene content of 3 to 10
% and an average degree of polymerization of about 400 to 1,500. The content of the vinyl chloride-ethylene copolymer as the binder resin in the charge generation layer is preferably as small as possible, but is usually in the range of 5 to 50% by weight. Further, the thickness of the charge generation layer is usually in the range of 0.05 to 1 μm. The solvent used to form the charge generation layer is a solvent that does not dissolve the alcohol-soluble nylon but dissolves the vinyl chloride-ethylene copolymer. Specific examples of such solvents include benzene, toluene, xylene, methylene chloride, chloroform, 1,2-dichloroethane, 1,1,2,
Examples include 2-tetrachloroethane, monochlorobenzene, dichlorobenzene, ethyl acetate, butyl acetate, methyl ethyl ketone, dioxane, tetrahydrofuran, cyclohexanone, methyl cellosolve, and ethyl cellosolve. In the multilayer organic photoreceptor according to the present invention, a charge transport layer is formed on the charge generation layer. Although the charge transport material is not particularly limited, for example, poly-N
-Vinylcarbazole and its derivatives, poly-γ-carbazolylethylglutamate and its derivatives, pyrene-formaldehyde condensate and its derivatives, polyvinylpyrene, polyvinylphenanthrene, oxazole derivatives, oxadiazole derivatives, imidazole derivatives, 9- (p-diethylaminostyryl)
Examples include electron-donating compounds or polymers such as anthracene, 1,1-bis(4-dibenzylaminophenyl)propane, styrylanthracene, styrylpyrazoline, phenylhydrazones, and α-stilbene derivatives. The binder resin used to form the charge transport layer is one that is soluble in an organic solvent and has high compatibility with the charge transport substance so that a solution of the charge transport substance can be stably and easily prepared. Furthermore, resins that are inexpensive, have high mechanical strength, and have excellent transparency and insulation properties are preferably used. Therefore, specific examples of such binder resins include polystyrene,
Styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyvinylidene chloride,
Polyarylate resin, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene,
Examples include thermoplastic or thermosetting resins such as poly-N-vinylcarbazole, acrylic resins, silicone resins, epoxy resins, melamine resins, urethane resins, phenolic resins, and alkyd resins. In addition, examples of the solvent include tetrahydrofuran, dioxane, toluene, monochlorobenzene, methylene chloride, chloroform,
1,2-dichloroethane, 1,1,2,2-
Examples include tetrachloroethane. The content of the charge transport substance in the charge transport layer is usually suitably in the range of 10 to 60% by weight, and the thickness of the charge transport layer is usually suitably in the range of 5 to 100 μm. The laminated organic photoreceptor according to the present invention is produced by coating an alcohol solution of an alcohol-soluble polyamide resin on a conductive support and drying it to form an undercoat layer as described above.
A dispersion containing an X-type metal-free phthalocyanine as a charge generating substance, an organic solvent, a vinyl chloride-ethylene copolymer as a binder resin, and a plasticizer as necessary is applied onto the undercoat layer and dried. to form a charge generation layer,
Further, a charge transporting layer can be obtained by applying a solution containing a charge transporting substance, an organic solvent, a binder, and, if necessary, a plasticizer, etc. thereon and drying it. Effects of the Invention As described above, the laminated organic photoreceptor of the present invention has an undercoat layer made of an alcohol-soluble polyamide resin between the conductive support and the charge generation layer, and has no X-type charge generation material. By using a metal phthalocyanine and a vinyl chloride-ethylene copolymer as a binder resin for forming the charge generation layer, it is possible to obtain a copied image without image defects. Since it has high sensitivity in the long wavelength range, it can be suitably used as a photoreceptor for laser beam printers. EXAMPLES The present invention will be explained below with reference to Examples, but the present invention is not limited to these Examples in any way. Example 1 Alcohol-soluble polyamide resin (Toray Industries, Inc.)
A solution consisting of 20 parts by weight of CM-8000, nylon 6/66/610/12 copolymer) and 313 parts by weight of methanol was applied by dipping onto the outer surface of an aluminum cylindrical tube with an outer diameter of 30 mm, and then heated at 90°C for 1 hour. It was dried by heating to form an undercoat layer with a thickness of 1 μm. Next, vinyl chloride-ethylene copolymer (VE-U manufactured by Tokuyama Sekisui Kogyo Co., Ltd., average degree of polymerization
1050, ethylene content 8%) 2.2 parts by weight, X
A mixture consisting of 3 parts by weight of type-free metal phthalocyanine and 200 parts by weight of tetrahydrofuran was pulverized in a ball mill for 2 hours to obtain a dispersion, which was applied by dip coating onto the undercoat layer.
It was heated and dried at ℃ for 30 minutes to form a charge generation layer with a thickness of 0.5 μm. Furthermore, Figure 1 shows the X-ray diffraction diagram (CuKα) of the above-mentioned X-type metal-free phthalocyanine.
line, powder method). Next, 130 parts by weight of polycarbonate (Iupilon E-2000 manufactured by Mitsubishi Gas Chemical Industries, Ltd.),
Structural formula 104 parts by weight of a charge transport substance and 1,
A solution consisting of 1004 parts by weight of 2-dichloroethane was applied by dip coating onto the above charge generation layer, and a solution of 60 to 110 parts by weight was applied.
The charge transport layer was formed by heating and drying while raising the temperature to 1° C./min at a rate of 1° C./min, thus producing a laminated photoreceptor. Comparative Example 1 When forming the charge generation layer, polyvinyl chloride (Zeon manufactured by Nippon Zeon Co., Ltd.) was used as the binder resin.
A laminated photoreceptor was manufactured in the same manner as in Example 1 except that 121) was used. Comparative Example 2 A charge generating layer was formed in the same manner as in Example 1, except that ethylene-vinyl acetate-vinyl chloride copolymer (Graftomer R-5, manufactured by Nippon Zen Co., Ltd.) was used as the binder resin. A laminated photoreceptor was manufactured. Comparative Example 3 When forming the charge generation layer, chlorinated polyvinyl chloride (manufactured by Tokuyama Sekisui Kogyo Co., Ltd.) was used as the binder resin.
A laminated photoreceptor was manufactured in the same manner as in Example 1 except that HA-15F) was used. Comparative Example 4 A laminated photoreceptor was manufactured in the same manner as in Example 1, except that polyvinyl butyral (Eslec BM-1 manufactured by Tokuyama Sekisui Kogyo Co., Ltd.) was used as the binder resin when forming the charge generation layer. . Comparative Example 5 A laminated photoreceptor was produced in the same manner as in Example 1, except that the undercoat layer was formed using polyvinyl alcohol (Gohsenol NH-26 manufactured by Nippon Gosei Kagaku Kogyo Co., Ltd.). did. Comparative Example 6 A laminated photoreceptor was produced in the same manner as in Example 1, except that no undercoat layer was formed. The performance of each of the laminated organic photoreceptors obtained as described above was evaluated using an apparatus as shown in FIG. This device is used during the actual laser beam printer.
This method measures the surface potential at a portion of the photoreceptor corresponding to the development position. First, while rotating the photosensitive drum 1 at 41 rpm, a corona discharger (scorotron) 2 is used to reduce the surface potential to -
Charge it to 650V, then turn on LED3 for static elimination.
was irradiated, and at this time, the surface potential V _L at the position of the probe 4 corresponding to the development position was determined.
Next, use a semiconductor laser for exposure at 780nm.
Continuing to irradiate the laser beam of 1.28 μJ/cm ² K,
After a few minutes, the surface potential V _R was determined. The results are shown in Table 1. Next, each photoreceptor was attached to a laser beam printer, and 10,000 copies were repeated, and the resulting images were examined for defects. The results are shown in Table 1. Compared to the case where no undercoat layer is provided (Comparative Example 6),

【table】

[Table] Although image defects are generally improved by forming an undercoat layer, the degree of improvement varies greatly depending on the resin forming the undercoat layer. That is,
When the undercoat layer was made of polyvinyl alcohol (Comparative Example 5), image defects were still significant. Also,
Even when an alcohol-soluble polyamide resin is used as the undercoat layer, depending on the type of binder resin for the charge generation layer, image defects still appear, or when no image defects occur, the image density is low. In contrast to these comparative examples, according to the present invention,
It is possible to obtain images with low _VR , no defects, and high density.

[Brief explanation of drawings]

FIG. 1 shows X used as a charge generating material in a multilayer organic photoreceptor according to the present invention.
FIG. 2 is an X-ray diffraction diagram (CuKα ray, powder method) of a type-free metal phthalocyanine, and is a diagram of an apparatus for evaluating the performance of a laminated organic photoreceptor. 1... Photosensitive drum, 2... Corona discharger, 3... LED for static elimination, 4... Probe for surface potential measurement.

Claims (1)

[Claims] 1. In a laminated organic photoreceptor comprising an undercoat layer, a charge generation layer, and a charge transport layer on a conductive support, the undercoat layer is made of an alcohol-soluble polyamide resin, and the charge generation layer is an X-type charge generation material. A laminated organic photoreceptor comprising a metal-free phthalocyanine and a vinyl chloride-ethylene copolymer as a binder resin.