JPH0469783B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an improved electrophotographic photoreceptor, and more particularly, an intermediate layer is provided between the base of the electrophotographic photoreceptor and a charge generation layer in order to sharpen the latent image on the electrophotographic photoreceptor for a red original. This invention relates to an electrophotographic photoreceptor. In conventional multilayer electrophotographic photoreceptors consisting of a charge transfer layer and a charge generation layer, the spectral absorption of the charge generation layer is
When copying a red original whose spectral reflectance peaks at 620nm or more using a halogen lamp, the relative sensitivity to the electrophotographic photoreceptor increases and the latent image on the photoreceptor becomes a black original. The drawback is that it is difficult to form. In order to make it easier to form a latent image from a red original, a filter is installed on the image exposure axis that hits the photoreceptor to cut out the red spectral wavelength, but this method has the disadvantage of being relatively expensive. It was hot. The present invention eliminates the above-mentioned drawbacks and provides an electrophotographic photoreceptor that can easily form a latent image on a red original without inserting a filter into the main body of the machine. That is, the present invention provides an electrophotographic photoreceptor having a substrate and a photosensitive layer having a charge generation layer and a charge transfer layer, in which a colored pigment having a maximum light absorption peak in a long wavelength region of 620 nm or more is provided between the substrate and the photosensitive layer. and an electrophotographic photoreceptor comprising a resin layer containing a conductive white pigment. The present invention includes a colored pigment that absorbs long wavelength light of 620 nm or more as an intermediate layer between the charge generation layer and the substrate in order to facilitate the formation of a latent image on a red original regardless of the absorption spectral distribution of the charge generation layer. A resin layer is provided. That is, this intermediate layer uses a blue colored pigment dispersed in a binder resin, and examples of the blue colored pigment include inorganic pigments such as Cobalt Blue, Cobalt Blue, Emerald Green, and Cerulean Blue, or phthalocyanine. Examples include organic pigments such as blue, pigment green, and fast sky blue. In addition, the resin for dispersing these blue colored pigments must have, for example, (1) strong adhesion to the substrate, (2) good powder dispersibility, and (3) solvent resistance. It can be used as long as it satisfies the following conditions:
Particularly suitable are thermosetting resins such as curable rubber, polyurethane resin, epoxy resin, alkyd resin, polyester resin, silicone resin, and acrylic-melamine resin. For dispersion, conventional methods such as roll mills, ball mills, vibrating ball mills, attritors, sand mills, colloid mills, etc. are used. Wire bar coating, blade coating, knife coating, roll coating, screen coating, etc. are suitable for coating when the substrate is sheet-shaped, and dip coating is suitable when the substrate is cylindrical. There is. In the present invention, if the intermediate layer has a volume resistivity of 10 ¹² Ω·cm or more when applied to the substrate, it may become difficult to form an image due to an increase in residual potential when an electrophotographic photoreceptor is produced. Therefore, in the present invention, a conductive white pigment such as tin oxide is added to the paint for the intermediate layer together with a colored pigment. If a charge generation layer is applied directly onto a coating film in which the above-mentioned colored pigment or colored pigment and conductive white pigment are dispersed, the pigment particles of the charge generation layer may become embedded in the micropores, or the photosensitive characteristics may deteriorate. changes. For this reason, it is preferable to provide a resin layer containing no conductive powder on the resin layer in which the pigment is dispersed. Examples of such resins include polyvinyl alcohol, polyvinyl methyl ether, polyvinylethyl ether, polyvinyl pyridine, polyvinyl pyrrolidone, polyethylene oxide, polyacrylic acids, methyl cellulose, ethyl cellulose, polyglutamic acid, casein, gelatin,
Examples include water-soluble resins such as starch, polyamide resins, phenolic resins, polyvinyl formals, polyurethane elastomers, alkyd resins, ethylene-vinyl acetate copolymers, vinylpyrrolidone-vinyl acetate copolymers, and other resins. According to the results of experiments conducted by the present inventor, polyamide resin was most suitable.
Polyamide resins are linear polyamides, and are typified by so-called nylons and copolymerized nylons. In the present invention, since it is suitable to apply it onto a substrate in a solution state, a low to non-crystalline one is preferable. Such a resin can be obtained by copolymerizing a mixture of two or more types of nylon raw materials. Raw materials for nylon include, for example, caprolactam or 6-aminocaproic acid, which is the raw material for nylon 6, hexamethylene diamine and dicarboxylic acids such as adipic acid and sebacic acid, which are the raw materials for nylon 66 and nylon 610, and dicarboxylic acids such as adipic acid and sebacic acid, and the raw materials for nylon 11.
Examples include 11-aminoundecanoic acid and ω-laurolactam or 12-aminododecanoic acid, which is a raw material for nylon 12. The coating thickness of the polyamide resin layer is preferably about 0.3 to 2 μm. A charge generation layer and a charge transport layer described below are formed on this resin layer containing no conductive powder to obtain an electrophotographic photoreceptor. The charge generation layer in the present invention includes azo pigments such as Sudan Red, Diane Blue, and Jenas Green B, Algol Yellow, Pyrenequinone,
Indanthrene, brilliant violet
Quinone pigments such as RRP, quinocyanine pigments, perylene pigments, indigo pigments such as indigo and thioindigo, bisbenzimidazole pigments such as India First Orange Toner, phthalocyanine pigments such as copper phthalocyanine, quinacridin pigments,
Charge-generating substances such as quinacridine pigments can be used with polyester, polystyrene, polyvinyl butyral,
It is formed by being dispersed in a binder resin such as polyvinylpyrrolidone, methylcellulose, polyacrylic esters, and cellulose ester. Its thickness is
It is about 0.01 to 1μ, preferably about 0.05 to 0.5μ. In addition, the charge transport layer may contain polycyclic aromatic compounds such as anthracene, pyrene, phenanthrene, coronene, indole, carbazole, etc. in the main chain or side chain.
Oxazole, isoxazole, thiazole,
imidazole, pyrazole, oxadiazole,
It is formed by dissolving a hole-transporting substance such as a compound having a nitrogen-containing cyclic compound such as pyrazoline, thiadiazole, or triazole, or a hydrazone compound in a resin that has film-forming properties. This is because the charge-transporting substance generally has a low molecular weight and has poor film-forming properties by itself. Examples of such resins include polycarbonates, polymethacrylates, polyarylates, polystyrene, polyesters, polysulfones, styrene-acrylonitrile copolymers, styrene-methyl methacrylate copolymers, and the like. The thickness of the charge transport layer is 5 to 20 microns. Additionally, the present invention allows the substrate to be selected from a wide variety of conductive materials. Specifically, metals such as aluminum, brass, stainless steel, and nickel can be shaped into cylinders or plates, and aluminum, indium oxide, and tin oxide can be vapor-deposited or laminated onto plastic or paper. Example 1 An aluminum cylinder of 60φ×260mm is prepared as a base. One group (Na ₆ Al ₆ (SiO ₄ ) ₆・2Na ₂ SO ₄ ) 80
(parts by weight, same hereinafter) and 20 parts of tin oxide powder, 80 parts of acrylic resin (product name: Acrydik A405, manufactured by Dainippon Ink Co., Ltd.) (solid content 50%), melamine resin (product name: Super The mixture was mixed with a solution of 20 parts of Betsukamine L121 (manufactured by Dainippon Ink Co., Ltd.) (solid content 60%) and 100 parts of toluene, and then dispersed in a ball mill for 6 hours. This dispersion was applied onto a substrate by a dipping method and thermally cured at 150° C. for 30 minutes to form an intermediate layer with a thickness of 25 μm. Next, copolymerized nylon resin (product name: Amilan
CM8000, manufactured by Toray Industries, Ltd.) (10 parts by weight, hereinafter the same) was dissolved in a mixed solution of 60 parts of methanol and 40 parts of butanol, and dip-coated on the above intermediate layer to form a polyamide resin layer with a thickness of 1 μm. Next, add 10 parts of the disazo pigment with the following structural formula. Cellulose acetate butyrate resin (product name: CAB-381;
(manufactured by Eastman Chemical) and 60 parts of cyclohexanone were dispersed for 20 hours using a sand mill device using 1φ glass beads. Add 100 parts of methyl ethyl ketone to this dispersion, dip coat it onto the polyamide resin layer, heat dry at 100°C for 10 minutes,
A charge generating layer was formed with a coating weight of 0.1 g/m ² . Next, add 10 parts of a hydrazone compound having the following structural formula. and 15 parts of styrene-methyl methacrylate copolymer resin (trade name: MS200; manufactured by Tetsu Seikagaku Co., Ltd.) were dissolved in 80 parts of toluene. This solution was coated on the charge generation layer and dried with hot air at 100℃ for 1 hour to form a 16μ
A thick charge transport layer was formed to prepare an electrophotographic photoreceptor. Comparative Example 1 The polyamide resin layer used in Example 1 was placed directly on the substrate without providing an intermediate layer on the same substrate as in Example 1,
An electrophotographic photoreceptor was prepared by sequentially forming a charge generation layer and a charge transport layer. The photoreceptors manufactured in Example 1 and Comparative Example 1 were -
5.6KV corona charging, image exposure, dry toner phenomenon,
Toner transfer to plain paper, urethane rubber blade (hardness 70°, pressure 10gw/cm, angle to photoreceptor)
The color sensitivity was evaluated by attaching it to an electrophotographic copying machine that has a cleaning process at 20°). A red original with the spectral reflectance of the drawing was copied using a development setting that allows an original with a density of 0.3 (using a Macbeth RD-514 density meter, the same applies hereinafter) to be copied to a density of 0.5, and the density of each copy was measured.

[Table] As explained above, between the substrate and the charge generation layer
By providing an intermediate layer containing a pigment that absorbs long wavelength light of 620 nm or more, an electrophotographic photoreceptor with good color reproducibility can be produced.

[Brief explanation of the drawing]

The drawing is a diagram showing the spectral reflectance of a red original.

Claims (1)

[Claims] 1. In an electrophotographic photoreceptor having a substrate and a photosensitive layer having a charge generation layer and a charge transfer layer, a colored pigment having a maximum light absorption peak in a long wavelength region of 620 nm or more and a conductive white are placed between the substrate and the photosensitive layer. An electrophotographic photoreceptor characterized by having a resin layer containing a pigment.