JP2000292954A - Electrophotographic photoreceptor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic electrophotographic photoreceptor which attains high image quality, a long service life and high reliability on a high level and to provide an electrophotographic photoreceptor excellent particularly in image quality reproducibility and excellent also in durability and photosensitivity. SOLUTION: At least an undercoat layer, an electric charge generating layer and an electric charge transferring layer are successively formed on an electrically conductive substrate to obtain the objective electrophotographic photoreceptor. The thickness of the electric charge transferring layer is <=15 μm and the undercoat layer comprises an inorganic material having <=1 μm particle diameter, an inorganic material having a fibrous structure and a bonding resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electrophotographic copying machine,
The present invention relates to electrophotographic photoconductors used in electrophotographic processes such as facsimile machines, laser printers, and direct digital plate making machines. More specifically, it relates to electrophotographic photoconductors having high sensitivity, high image quality, and excellent durability. It is.

[0002]

2. Description of the Related Art An electrophotographic method using an electrophotographic photosensitive member applied to a copying machine, a facsimile, a laser printer, a direct digital plate making machine, and the like includes at least primary charging, image exposure, After the development process, this method comprises a process of transferring a toner image to an image carrier (transfer paper), fixing, and cleaning the surface of the electrophotographic photosensitive member.

The basic characteristics required for an electrophotographic photoreceptor in this electrophotographic method are that it can be charged to an appropriate potential in a dark place, that there is little dissipation of electric charge in a dark place, and that the charge is quickly charged by light irradiation. Can be dissipated. Further, in addition to these characteristics, long-term reliability such as image quality characteristics, low pollution, and low cost are required.

Conventionally, as a photoreceptor used in an electrophotographic system, a photoconductive layer having a photoconductive layer mainly composed of selenium or a selenium alloy on a conductive support, or an inorganic photoconductive material such as zinc oxide and cadmium sulfide is used. A material in which a material is dispersed in a binder and a material using an amorphous silicon-based material are generally known, but in recent years, the cost is low, the degree of freedom in photoconductor design is high, and BACKGROUND ART Organic photoconductors have been widely used due to pollution and the like.

[0005] Organic electrophotographic photoreceptors include a photoconductive resin represented by polyvinyl carbazole (PVK), P
VK-TNF (2,4,7-trinitrofluorenone)
A charge-transfer complex type represented by, a pigment dispersion type represented by a phthalocyanine-binder, a function-separated type photoconductor using a combination of a charge-generating substance and a charge-transporting substance, and the like are known. Photoreceptors are receiving attention.

The mechanism of the formation of an electrostatic latent image in a function-separated type photoreceptor is that, when the photoreceptor is charged and irradiated with light, the light passes through a transparent charge transport layer and is charged by the charge generating substance in the charge generation layer. The absorbed charge-generating substance, which has absorbed light, generates charge carriers, which are injected into the charge-transporting layer, move in the charge-transporting layer in accordance with the electric field generated by the charging, and charge the photoreceptor surface. The latent image is formed by neutralization. In a function-separated type photoreceptor, it is known and useful to use a charge transport material having absorption mainly in the ultraviolet region and a charge generation material having absorption mainly in the visible region.

[0007] At present, the electrophotographic photoreceptor uses a digital recording technique in which an image can be easily converted and edited, and the resolution of electrophotography is high with respect to digital light such as a laser or an LED array. Reproduction of density is required.

In order to satisfy this requirement, a method for sharpening the potential distribution of an electrostatic latent image has been used as a means for achieving high definition and high image quality even for a photoconductor for electrophotography. As one of the methods, a method of reducing the thickness of the photoconductor of the electrophotographic photoconductor can be considered.

For example, in the case of a laminated photoreceptor, the charge generated in the charge generation layer is injected into the charge transport layer, moves along the electric field to the surface, neutralizes the surface potential of the photoreceptor, and forms an electrostatic latent image. Formed, the electric field strength is increased by reducing the thickness of the charge transport layer, and the diffusion of charges in the direction perpendicular to the electric field is suppressed by decreasing the diffusion distance, and it is sharp and faithful to digital light such as laser light. It is possible to form a stable electrostatic latent image.

[0010] Considering the photoreceptor as a kind of dielectric,
By reducing the film thickness, the electrostatic capacity of the photoconductor increases, and therefore, the charge density on the photoconductor surface to obtain a desired surface potential increases. As a result, the developing electric field increases, and the electrostatic latent image The potential becomes deeper in the direction of the potential, and high resolution is realized.

However, in the conventional photoreceptor, when the film thickness is reduced, the electric field intensity increases, so that charge injection from the support side is promoted, and a phenomenon such as a decrease in charging ability and fogging in reversal development appears. Further, there is a problem that the fluctuation of the potential at the time of repeated use becomes large, and in particular, the bright portion potential irreversibly increases. Although the cause has not been fully elucidated yet, it is considered that a large current flows inside the photoconductor due to the increase in the electric field strength, and that the photoconductor material is deteriorated with the endurance. Therefore, when the thickness of the photoreceptor is reduced, the reproducibility of minute dots of digital light such as a laser beam is improved, and the resolution is improved. However, there is a problem in practical use due to the adverse effect of charge injection.

An electrophotographic photoreceptor basically comprises a support and a photosensitive layer formed on the support. As the support, a metal having high conductivity is often used, and among them, aluminum or an aluminum alloy is often used. On these surfaces, projections, structural defects such as foreign matter, oil and chemical impurities such as rust-preventive oil are present, so if the photosensitive layer is provided on the support as it is, image defects will occur. It cannot be used as is.

As one of techniques for solving this problem, it has been proposed to provide a photosensitive layer after providing an undercoat layer on a conductive support. Examples thereof include a resin substrate having a resin layer provided on a conductive support, and a resin in which inorganic pigments (titanium oxide, tin oxide, etc.) are dispersed in a resin (Japanese Patent Laid-Open No. 61-2046).
No. 42, etc.) are known.

This method has been applied to a large number of photoreceptors because of its relatively low cost and good effect. However, in conventional electrophotographic photoreceptors having an undercoating layer of only a resin or an undercoating layer in which an inorganic pigment is dispersed in a resin, it cannot be said that there is no problem in electrostatic repetition characteristics. There has been a problem in that the electrophotographic characteristics deteriorate, especially the charging potential decreases, and the surface potential decreases during the time from charging to development, that is, so-called dark decay increases with use.

Further, even when there is no problem in the electrostatic electrophotographic characteristics, when an image is formed through an electrophotographic process such as a general Carlson process or a similar process, it is called a white spot or a black spot. Image defects often occurred. Therefore, these conventional photoreceptors still lack one of the conditions that the charge potential is stable and the charge can be quickly dissipated by light irradiation, that is, one of photosensitivity and image quality.

That is, an electrophotographic photoreceptor which satisfies all of charge stability, photosensitivity and image quality and has long-lasting properties of these characteristics has not been obtained. In other words, the conventional electrophotographic photoreceptors are insufficient to achieve a high level of high performance, long life, and high reliability recently required for electrophotographic engines, and improvements are strongly desired. Was.

[0017]

SUMMARY OF THE INVENTION An object of the present invention is to provide an organic electrophotographic photoreceptor which achieves high image quality, long life and high reliability at a high level. It is an object of the present invention to provide an electrophotographic photosensitive member having excellent properties and photosensitivity, an electrophotographic method using the same, an electrophotographic apparatus, and a process cartridge for the electrophotographic apparatus.

[0018]

Means for Solving the Problems As a result of diligent studies of the above-mentioned problems, the present inventors have found that an electrophotographic photoreceptor comprising at least an undercoat layer, a charge generation layer and a charge transport layer sequentially formed on a conductive substrate. Wherein the charge transport layer has a thickness of 15 μm or less, and the undercoat layer comprises an inorganic substance having a particle diameter of 1 μm or less, an inorganic substance having a fibrous structure, and a binder resin. The fibrous substance used in the undercoat layer of the electrophotographic photoreceptor has a specific structure and size, a specific binder resin, a charge generating substance, and a charge transporting substance. It has also been found that the use of a liquid crystal provides very good characteristics, and a great advantage in designing various electrophotographic image forming apparatuses.

In the electrophotographic photosensitive member of the present invention, the thickness of the charge transport layer is limited to a specific value, and by making the charge transport layer thin, the diffusion of charges when an electrostatic latent image is formed on the surface of the photosensitive member is suppressed. And
An electrostatic latent image that is faithful to very high density and fine writing can be formed, and a high-quality image can be obtained. Also,
By combining an inorganic substance having a particle size of 1 μm or less with an inorganic substance having a fibrous structure, the shape of the inorganic substance used for the undercoat layer provided on the conductive support is extremely low. Improved, effectively preventing charge injection from the substrate even under a high electric field caused by the thinning of the charge transport layer, and stably obtaining the high-quality image even during repeated use. Has been found to be possible.

Further, when the substance having a fibrous structure is contained in an amount of 0.1 to 5 parts by weight per 10 parts by weight of the inorganic pigment, the charge stability upon repeated use is further improved.
By using an alkyd resin and a melamine resin as the binder resin of the undercoat layer used when forming these inorganic substances having different shapes, it is possible to obtain a high-quality film without coating film defects, and to achieve higher image quality. Image can be obtained.

In addition, the charge generation material contained in the charge generation layer is oxytitanyl phthalocyanine, and the charge transport material having the structure represented by the following general formula in the charge transport layer having the specific thickness.

[0022]

Embedded image(Where R₁, R_Two, R_ThreeAnd R_FourIs a hydrogen atom,
Or unsubstituted lower alkyl group, substituted or unsubstituted
Represents a reel group, Ar₁Is a substituted or unsubstituted aryl
Ar represents a group_TwoRepresents a substituted or unsubstituted arylene group
And Ar₁And R ₁May together form a ring, and
n is an integer of 0 or 1. ) By using
The sensitivity of the electrostatic latent image
It is possible to obtain a very good high resolution image without any.

Further, the present invention provides the above electrophotographic photoreceptor
7. An electrophotographic method in which at least charging, image exposure, development, transfer, cleaning and charge elimination are repeatedly performed, wherein the electrophotographic photosensitive member is one according to claim 1 to 6, wherein at least an electrophotographic photosensitive member is used. An electrophotographic apparatus comprising a body, wherein the electrophotographic photosensitive member is any one of claims 1 to 6, and at least an electrophotographic photosensitive member. A process cartridge for an electrophotographic apparatus, comprising: a process cartridge for an electrophotographic apparatus, wherein the electrophotographic photoreceptor is any one of claims 1 to 6.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an electrophotographic photosensitive member used in the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing the structure of the electrophotographic photoreceptor of the present invention, and includes a conductive support (31), a charge generation layer (41), and a charge transport layer (43).
And an undercoat layer (35) formed between the photosensitive layer (33) and the photosensitive layer (33).

First, the conductive support used in the present invention will be described. The conductive support (3) used in the present invention
As 1), those exhibiting a conductivity of 10 ¹⁰ Ω · cm or less, for example, metals such as aluminum, nickel, chromium, nichrome, copper, silver, gold, platinum, iron, tin oxide,
An oxide such as indium oxide, a film or cylindrical plastic by evaporation or sputtering,
A plate coated with paper or the like, or a plate made of aluminum, an aluminum alloy, nickel, stainless steel, etc. I. , I. I. For example, pipes that have been surface-treated by cutting, superfinishing, polishing, or the like can be used after forming into a tube by a method such as extrusion or drawing.

Next, the undercoat layer (3) used in the present invention
5) will be described. The undercoating layer used in the present invention is composed of an inorganic pigment having a particle size of 1 μm or less, an inorganic substance having a fibrous structure, and a binder resin. Considering that the resin is applied, it is desirable that the resin be a resin having high solvent resistance to general organic solvents. Examples of such a resin include water-soluble resins such as polyvinyl alcohol, casein, and sodium polyacrylate, alcohol-soluble resins such as copolymerized nylon and methoxymethylated nylon, polyurethane, melamine resins, phenol resins, alkyd resins, and epoxy resins. And a curable resin that forms a three-dimensional network structure. In particular, when an alkyd resin and a melamine resin are used, a film excellent in characteristics can be obtained.
In addition, as the inorganic substance used in the present invention, titanium oxide, silica, alumina, zirconium oxide, tin oxide,
Examples thereof include metal oxides such as indium oxide and the like, which are formed into fine powder having a particle size of 1 μm or less by a pulverizing method such as a ball mill. Further, as the inorganic substance having a fibrous structure used in combination with the inorganic substance having a particle diameter of 1 μm or less in the present invention, white needle-like crystals of calcium carbonate, calcium silicate hydrate, needle-like titanium oxide,
Examples include basic magnesium sulfate and zinc oxide.

Among them, the average fiber length is 1 to 5 μm,
When a substance having a fiber structure having an average particle size of 0.1 to 0.5 μm is used, excellent electrophotographic characteristics, and when formed by an electrophotographic method, extremely excellent durability stability, a defect-free high Image quality can be obtained.

The undercoat layer of the present invention can be formed by wet coating such as dip coating, spray coating or blade coating using an appropriate solvent and coating method.
The thickness of the undercoat layer used in the present invention is 0.01 to 10 μm.
m is appropriate.

Next, the photosensitive layer (33) in the present invention will be described. First, the charge generation layer (41) will be described. The charge generation layer (41) is a layer containing a charge generation substance as a main component, and may use a binder resin as needed. Known materials can be used as the charge generating substance. For example, copper phthalocyanine, metal phthalocyanine such as iron phthalocyanine, phthalocyanine-based pigments such as metal-free phthalocyanine, azulhenium salt pigment, squaric acid methine pigment, azo pigment having a carbazole skeleton, azo pigment having a triphenylamine skeleton, diphenylamine skeleton Azo pigment having a dibenzothiophene skeleton, azo pigment having a fluorenone skeleton, azo pigment having an oxadiazole skeleton, azo pigment having a bisstilbene skeleton, azo pigment having a distyryl oxadiazole skeleton, distyrylcarbazole Azo pigments having a skeleton, perylene pigments, anthraquinone or polycyclic quinone pigments, quinone imine pigments, diphenylmethane and triphenylmethane pigments,
Examples include benzoquinone and naphthoquinone pigments, cyanine and azomethine pigments, indigoid pigments, bisbenzimidazole pigments, and the like. Among them, Y-type oxotitanium phthalocyanine is preferable in terms of its characteristics. These charge generating substances can be used as a mixture of two or more kinds.

The binder resin used as needed for the charge generation layer (41) includes polyamide, polyurethane, epoxy resin, polyketone, polycarbonate, silicone resin, acrylic resin, polyvinyl butyral,
Polyvinyl formal, polyvinyl ketone, polystyrene, poly-N-vinyl carbazole, polyacrylamide and the like are used. These binder resins can be used alone or as a mixture of two or more.

The method of forming the charge generation layer (41) includes:
A vacuum thin film preparation method and a casting method from a solution dispersion system are mainly mentioned. In the former method, a vacuum deposition method or the like is used, and a good formation can be achieved. Further, in order to provide a charge generation layer by a casting method described later, if the inorganic or organic charge generation material described above is necessary, a ball mill and an atomizer using a solvent such as tetrahydrofuran, cyclohexanone, dioxane, dichloroethane, butanone together with a binder resin if necessary. Dispersed by lighter, sand mill, etc.,
The dispersion can be formed by appropriately diluting and applying the dispersion. The coating can be performed by a dip coating method, a spray coating method, a bead coating method, or the like. The thickness of the charge generation layer provided as described above is appropriately about 0.01 to 5 μm, and preferably 0.05 to 2 μm.

Next, the charge transport layer (43) will be described. The charge transporting layer (43) can be formed by dissolving or dispersing the charge transporting substance and the binder resin in a suitable solvent, applying the solution on the charge generating layer, and drying. If necessary, a plasticizer, a leveling agent, an antioxidant and the like can be added.

The charge transport material includes a hole transport material and an electron transport material. Examples of the charge transport material include chloranil, bromanil, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenone, 2,4,5,7-tetranitro-9-fluorenone, 2,4 , 5,7-tetranitroxanthone,
2,4,8-trinitrothioxanthone, 2,6,8-
Examples thereof include electron accepting substances such as trinitro-4H-indeno [1,2-b] thiophen-4-one, 1,3,7-trinitrodibenzothiophene-5,5-dioxide, and benzoquinone derivatives.

Examples of the hole transport material include poly-N-vinylcarbazole and its derivatives, poly-γ-carbazolylethylglutamate and its derivatives, pyrene-formaldehyde condensate and its derivatives, polyvinylpyrene, polyvinylphenanthrene, polysilane, Oxazole derivatives, oxadiazole derivatives, imidazole derivatives, monoarylamine derivatives, diarylamine derivatives, triarylamine derivatives, stilbene derivatives,
α-phenylstilbene derivative, benzidine derivative, diarylmethane derivative, triarylmethane derivative, 9
And other known materials such as styryl anthracene derivatives, pyrazoline derivatives, divinylbenzene derivatives, hydrazone derivatives, indene derivatives, butadiene derivatives, pyrene derivatives, etc., bisstilbene derivatives, enamine derivatives and the like. These charge transport materials are used alone or in combination of two or more.

Among these many charge transport materials, those having a structure represented by the following general formula have particularly excellent properties.

[0036]

Embedded image(Where R₁, R_Two, R_ThreeAnd R_FourIs a hydrogen atom,
Or unsubstituted lower alkyl group, substituted or unsubstituted
Represents a reel group, Ar₁Is a substituted or unsubstituted aryl
Ar represents a group_TwoRepresents a substituted or unsubstituted arylene group
And Ar₁And R ₁May together form a ring, and
n is an integer of 0 or 1. )

Next, specific examples of the substituents represented by Ar ₁ , Ar ₂ , R ₁ , R ₂ , R ₃ and R ₄ are shown below.

[0038]

[Table 1-1]

[0039]

[Table 1-2]

[0040]

[Table 1-3]

[0041]

[Table 1-4]

[0042]

[Table 1-5]

[0043]

[Table 1-6]

Examples of the binder resin for the charge transport layer include polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, and vinyl chloride-vinyl acetate. Polymer, polyvinyl acetate, polyvinylidene chloride, polyalate, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinyl carbazole, acrylic resin, silicone resin, epoxy resin, Thermoplastic or thermosetting resins such as melamine resin, urethane resin, phenol resin, and alkyd resin can be used. These binders can be used alone or as a mixture of two or more.

The amount of the charge transporting material is suitably from 20 to 300 parts by weight, preferably from 40 to 150 parts by weight, per 100 parts by weight of the binder resin. As the solvent used here, tetrahydrofuran, dioxane, toluene, dichloromethane, monochlorobenzene, dichloroethane, cyclohexanone, methyl ethyl ketone, acetone and the like are used.

In the present invention, the charge transport layer (43)
A plasticizer or a leveling agent may be added therein. As the plasticizer, those used as plasticizers for general resins such as dibutyl phthalate and dioctyl phthalate can be used as they are, and the amount of the plasticizer is about 0.1 to 30 parts by weight based on 100 parts by weight of the binder resin. Is appropriate. As the leveling agent, silicone oils such as dimethyl silicone oil and methylphenyl silicone oil, and polymers or oligomers having a perfluoroalkyl group in a side chain are used. About 0.01 to 1 part by weight is appropriate.

In the present invention, an antioxidant can be added for the purpose of improving environmental resistance, in particular, for the purpose of preventing a decrease in sensitivity and an increase in residual potential. The antioxidant may be added to any layer containing an organic substance, but good results can be obtained by adding it to a layer containing a charge transporting substance.

The following are examples of the antioxidant that can be used in the present invention. [Monophenolic compound] 2,6-di-t-butyl-
p-cresol, butylated hydroxyanisole, 2,
6-di-t-butyl-4-ethylphenol, stearyl-β- (3,5-di-t-butyl-4-hydroxyphenyl) propionate and the like.

[Bisphenol compounds] 2,2'-methylene-bis- (4-methyl-6-t-butylphenol), 2,2'-methylene-bis- (4-ethyl-6
t-butylphenol), 4,4'-thiobis- (3-
Methyl-6-t-butylphenol), 4,4′-butylidenebis- (3-methyl-6-t-butylphenol) and the like.

[Polymer phenolic compound] 1,1,3
-Tris- (2-methyl-4-hydroxy-5-t-butylphenyl) butane, 1,3,5-trimethyl-2,
4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, tetrakis- [methylene-3
-(3 ', 5'-di-t-butyl-4'-hydroxyphenyl) propionate] methane, bis [3,3'-bis (4'-hydroxy-3'-t-butylphenyl) butyric acid ] Glycol esters, tocophenols and the like.

[Paraphenylenediamines] N-phenyl-N'-isopropyl-p-phenylenediamine,
N, N'-di-sec-butyl-p-phenylenediamine, N-phenyl-N-sec-butyl-p-phenylenediamine, N, N'-di-isopropyl-p-phenylenediamine, N, N'- Dimethyl-N, N'-di-t
-Butyl-p-phenylenediamine and the like.

[Hydroquinones] 2,5-di-t-octylhydroquinone, 2,6-didodecylhydroquinone, 2-dodecylhydroquinone, 2-dodecyl-5
-Chlorohydroquinone, 2-t-octyl-5-methylhydroquinone, 2- (2-octadecenyl) -5-
Methylhydroquinone and the like.

[Organic sulfur compounds] dilauryl-3,
3'-thiodipropionate, distearyl-3,3 '
-Thiodipropionate, ditetradecyl-3,3'-
Thiodipropionate and the like.

[Organic phosphorus compounds] Triphenylphosphine, tri (nonylphenyl) phosphine, tri (dinonylphenyl) phosphine, tricresylphosphine, tri (2,4-dibutylphenoxy) phosphine and the like. These compounds are known as antioxidants for rubber, plastics, oils and the like, and commercially available products can be easily obtained.
In the present invention, the amount of the antioxidant added depends on the charge transport material 1
The amount is 0.1 to 100 parts by weight, preferably 2 to 30 parts by weight based on 00 parts by weight.

Next, the electrophotographic method and the electrophotographic apparatus of the present invention will be described in detail. In FIG. 2, the electrophotographic apparatus includes a static elimination lamp (2), a charger (3), and an eraser (3) in a counterclockwise direction close to the upper surface of a drum-shaped photoconductor (1) and along the circumference. 4), image exposing section (5), developing unit (6), pre-transfer charger (7), transfer charger (10), separation charger (1)
1), separation claw (12), charger (1
3), fur brush (14), cleaning brush (1
5) is sequentially attached. Further, a registration roller (8) for feeding the transfer paper (9) between the photoreceptor (1), the transfer charger (10) and the separation charger (11) is provided. The photoreceptor (1) comprises a drum-shaped conductive support and a photosensitive layer in close contact with the upper surface thereof, and rotates counterclockwise.

In the electrophotographic method using the above electrophotographic apparatus, the photoreceptor (1) rotates counterclockwise, is negatively (or positively) charged by the charging charger (3), and is exposed to an image. By the exposure from (5), an electrostatic latent image is formed on the photoconductor (1).

As the transfer means, the above-mentioned charger can be generally used, but as shown in the figure, the transfer charger (10)
It is effective to use a combination of the above and the separation charger (11).

Light sources used in the image exposure section (5), the neutralizing lamp (2) and the like include a fluorescent lamp, a tungsten lamp, a halogen lamp, a mercury lamp, a sodium lamp, a light emitting diode (LED), and a semiconductor laser (LD). And a light emitting material such as electroluminescence (EL). To irradiate only light in a desired wavelength range, various filters such as a sharp cut filter, a band pass filter, a near infrared cut filter, a dichroic filter, an interference filter, and a color temperature conversion filter can be used. The light source and the like are provided with a transfer step using light irradiation, a charge removal step, a cleaning step, or a step such as pre-exposure in addition to the step illustrated in FIG. Can also be used.

In the developing unit (6), toner is adhered to the photoreceptor (1) to form an electrostatic latent image, the charged state of the toner image is adjusted by the pre-transfer charger (7), and then the transfer charger ( The toner image is transferred to the transfer paper (9) by (10), the electrostatic adhesion between the photoconductor (1) and the transfer paper (9) is eliminated by the separation charger (11), and the transfer is performed by the separation claw (12). The paper (9) is separated from the photoconductor (1). After the transfer paper (9) is separated, the surface of the photoconductor (1) is cleaned with the pre-cleaning charger (13), fur brush (14), and cleaning brush (15). This cleaning is performed by a cleaning brush (15).
This can also be performed by removing the remaining toner.

When a negative (or positive) charge is applied to the photoreceptor to perform image exposure, a negative (or positive) electrostatic latent image is formed on the photoreceptor. If this is developed with a positively (or negatively) charged toner (electrostatic fine particles), a positive image can be obtained, and if it is developed with a negatively (or positively) charged toner, a negative image can be obtained. A known method can be applied to such a developing unit, and a known method is also used for the charge removing unit.

In this example, the conductive support is shown as a drum, but a sheet or an endless belt can be used. As the pre-cleaning charger, known charging means such as a corotron, a scorotron, a solid state charger (solid state charger), a charging roller and the like can be used. For the transfer charger and the separation charger, the above-mentioned charging means can be usually used.
As shown in FIG. 2, a charger in which the transfer charger and the separation charger are integrated is efficient and preferable. As the cleaning brush, a known brush such as a fur brush or a mag fur brush can be used.

FIG. 3 is a schematic diagram illustrating another example of the electrophotographic apparatus (process) of the present invention. In this example, the belt-shaped photoreceptor (21) has a TiOPc photosensitive layer in which a specific impurity content is specified, is driven by drive rollers (22a) and (22b), and is charged by a charger (23). , Image exposure by an image exposure source (24), development (not shown), transfer by a transfer charger (25), pre-cleaning exposure by a pre-cleaning exposure section (26), cleaning by a cleaning brush (27), static elimination light source A series of image formation including the charge removal by (28) is repeatedly performed. In this case, the exposure of the exposed portion before cleaning is performed from the conductive support side of the photoconductor (21). Of course, in this case, the conductive support is translucent.

The electrophotographic process illustrated above is an example of an embodiment of the present invention, and other embodiments are of course possible. For example, in FIG. 3, the exposure before cleaning can be performed from the photosensitive layer side, and the exposure of the image exposure section and the charge removal exposure section can also be performed from the conductive support side.

On the other hand, as the light irradiation step, image exposure, pre-cleaning exposure, and charge removal exposure are shown. In addition, pre-transfer exposure, pre-exposure of image exposure, and other known light irradiation steps are provided. The photoreceptor can be irradiated with light.

The image forming means of the present invention as described above may be fixedly incorporated in an apparatus such as a copying machine, a facsimile, a printer, or the like, but may be incorporated in the apparatus in the form of a process cartridge. Is also good. The process cartridge is one device (part) that includes a photoconductor and further includes a charging unit, an exposure unit, a developing unit, a transfer unit, a cleaning unit, and a charge removing unit. There are many shapes and the like of the process cartridge. As a general example, the one shown in FIG. The process cartridge shown in FIG. 4 includes a charging charger (17), a cleaning brush (18), an image exposure unit (19), and a developing roller (20) arranged around a photoconductor (16).
And so on.

[0066]

Next, the present invention will be described in more detail by way of examples, but the present invention is not limited to the following examples. All parts used in the examples are parts by weight. Example 1 A coating liquid for an undercoat layer, a coating liquid for a charge generation layer, and a coating liquid for a charge transport layer, which were prepared as described below, were successively applied and dried on an aluminum drum having a diameter of 30 mm. Thus, an undercoat layer of 3 μm, a charge generation layer of 0.2 μm, and a charge transport layer of 12.2 μm were formed to obtain an electrophotographic photoreceptor of the present invention.

[Coating solution for undercoat layer] Titanium oxide powder (Taipec CR-EL, manufactured by Ishihara Sangyo) 60 parts Polyamide resin (Amilan CM8000, manufactured by Toray) 90 parts Methanol 1400 parts n-butanol 600 parts Then, the mixture was subjected to ball mill pulverization, the dispersion conditions were adjusted so that the average particle diameter of the titanium oxide powder was 0.2 μm, and the mixture was filtered through a stainless steel mesh to prepare a dispersion liquid having a particle diameter of 1 μm. To this dispersion was added 35 parts of magnesium oxysulfate whisker (Moss Heidi, manufactured by Ube Chemical Industries) having an average fiber length of 10 μm and an average fiber diameter of 0.7 μm, and the mixture was sufficiently stirred to obtain a coating liquid for an undercoat layer.

[Coating Liquid for Charge Generating Layer] The following components were mixed and dispersed by a ball mill. Metal-free phthalocyanine pigment (Fastgen Blue 8120B, manufactured by Dainippon Ink and Chemicals, Inc.) 2 parts Polyvinyl butyral (Eslec BM-S, manufactured by Sekisui Chemical) 0.2 part Tetrahydrofuran 50 parts This dispersion was used as a coating solution for a charge generation layer. did.

[Coating Liquid for Charge Transport Layer] The following components were mixed and dissolved to prepare a coating liquid for charge transport layer. 7 parts of charge transport material having the following structure

[0070]

Embedded image Polycarbonate 10 parts Methylene chloride 100 parts

Example 2 In the coating liquid for the undercoat layer in Example 1, the average fiber length was 5.2 μm and the average fiber diameter was 0.3 μm instead of magnesium oxysulfate whisker (Moss Heidi, manufactured by Ube Chemical Industries, Ltd.). The electrophotographic photosensitive member of Example 2 was obtained in exactly the same manner as in Example 1, except that the same amount of needle-like titanium oxide (FTL-300, manufactured by Ishihara Sangyo) was used.

Example 3 In the coating liquid for undercoat layer in Example 1, the average fiber length was 2 μm and the average fiber diameter was 0.2 μm instead of magnesium oxysulfate whisker (Moss Heidi, manufactured by Ube Chemical Industries, Ltd.). An electrophotographic photoreceptor of Example 3 was obtained in exactly the same manner as in Example 1, except that the same amount of calcium silicate hydrate (Zonolite, manufactured by Ube Chemical Industry) was used.

Example 4 In the coating liquid for undercoat layer in Example 3, calcium silicate hydrate (Zonolite,
The electrophotographic photoreceptor of Example 4 was obtained in exactly the same manner as in Example 3 except that the amount of Ube Chemical Industry was 3 parts.

Example 5 In the coating liquid for undercoat layer in Example 4, an alkyd resin (Beccolite M6401-50EL, manufactured by Dainippon Ink and Chemicals, Inc.) was used instead of using a polyamide resin (CM8000, manufactured by Toray). 12
Part and melamine resin (Super Beckamine G-821
-6, manufactured by Dainippon Ink and Chemicals, Inc.) and the electrophotographic photoreceptor of Example 5 was carried out in exactly the same manner as in Example 4, except that 50 parts of methyl ethyl ketone were used instead of using methanol and n-butanol. Produced.

Example 6 The same amount of the Y-type oxotitanyl phthalocyanine pigment was used in place of the metal-free phthalocyanine pigment (Fastgen Blue 8120B, manufactured by Dainippon Ink and Chemicals) in the coating solution for the charge generation layer in Example 5. Except for using, an electrophotographic photosensitive member of Example 6 was produced in exactly the same manner as in Example 5.

Example 7 The electrophotographic photoreceptor of Example 7 was manufactured in the same manner as in Example 5, except that the charge transport material used in the charge transport layer in Example 5 was changed to the one having the following structure. Produced.

[0077]

Embedded image

Comparative Example 1 An electrophotographic photoreceptor of Comparative Example 1 was produced in exactly the same manner as in Example 1 except that the undercoat layer was not provided.

Comparative Example 2 In the undercoat layer coating liquid in Example 1, the average particle diameter of the titanium oxide powder was 1.5 μm.
The electrophotographic photoreceptor of Comparative Example 2 was produced in exactly the same manner as in Example 1 except that the dispersion conditions were adjusted so as to obtain a dispersion liquid.

Comparative Example 3 An electrophotographic photoreceptor of Comparative Example 3 was prepared in exactly the same manner as in Example 1 except that the magnesium oxysulfate whisker was not added to the undercoat layer coating liquid in Example 1. .

Comparative Example 4 An electrophotographic photosensitive member of Comparative Example 4 was produced in the same manner as in Example 1, except that the titanium oxide powder was not added.

The electrophotographic photoreceptors of Examples 1 to 7 and Comparative Examples 1 to 4 thus produced were subjected to a modification of an electrophotographic copying machine Imagio MF200 (manufactured by Ricoh Co., Ltd.) to obtain 35,000 sheets of each photoreceptor. Paper-passing test was performed. The potential characteristics and the image quality characteristics of the photoreceptor were evaluated at an early stage of the paper-passing test and after 35,000 sheets of the paper-passing test.

Dark part potential: Surface potential of photosensitive member when moved to developing position after primary charging Light portion potential: Photosensitive member when subjected to image exposure (solid exposure) after primary charging and moved to developing position Surface potential Image quality: Comprehensive evaluation of solid density, fine line reproducibility, local defects such as black spots, background contamination, abnormal images, etc. Table 2 shows the evaluation results.

[0084]

[Table 2]

As is clear from Table 2, the electrophotographic photosensitive members of Examples 1 to 7 satisfying the claims of the present invention
It can be seen that the dark portion potential is excellent in the repetition of the bright portion potential, the deterioration of the electric characteristics is small, and a high-quality hard copy can be stably obtained for a long time. On the other hand, in the electrophotographic photoreceptors of Comparative Examples 1 to 4, any one of the electrical characteristics and the image characteristics is greatly deteriorated in a short period, and the superiority of the photoreceptor of the present invention is apparent.

As is apparent from the detailed and specific description, the present invention can provide an electrophotographic photosensitive member having excellent photosensitivity, abrasion resistance and image quality stability.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of an electrophotographic photosensitive member according to the present invention.

FIG. 2 is a schematic view for explaining an electrophotographic process and an electrophotographic apparatus of the present invention.

FIG. 3 is a schematic view illustrating another example of the electrophotographic process and the electrophotographic apparatus of the present invention.

FIG. 4 is a view showing a process cartridge of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 photoconductor 2 static elimination lamp 3 charging charger 4 eraser 5 image exposure unit 6 developing unit 7 pre-transfer charger 8 registration roller 9 transfer paper 10 transfer charger 11 separation charger 12 separation claw 13 pre-cleaning charger 14 fur brush 15 cleaning brush 16 photoconductor 17 Charging Charger 18 Cleaning Brush 19 Image Exposure Unit 20 Developing Roller 21 Photoconductor 22a Driving Roller 22b Driving Roller 23 Charging Charger 24 Image Exposure Source 25 Transfer Charger 26 Pre-Cleaning Exposure 27 Cleaning Brush 28 Static Elimination Light Source 31 Conductive Support 33 Photosensitive Layer 35 undercoat layer 41 charge generation layer 43 charge transport layer

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Adult Kojima 1-3-6 Nakamagome, Ota-ku, Tokyo F-term in Ricoh Co., Ltd. 2H068 AA19 AA20 AA43 AA44 BA12 BA39 BB37 FA01 FA13 FA27

Claims (8)

[Claims] 1. An electrophotographic photoreceptor comprising at least an undercoat layer, a charge generation layer and a charge transport layer formed sequentially on a conductive support, wherein the thickness of the charge transport layer is 15 μm or less, and An electrophotographic photosensitive member, wherein the undercoat layer comprises an inorganic substance having a particle size of 1 μm or less, an inorganic substance having a fibrous structure, and a binder resin. 2. The electrophotographic photosensitive member according to claim 1, wherein the inorganic substance having a fibrous structure has an average fiber length of 1 to 5 μm and an average fiber diameter of 0.1 to 0.5 μm. 3. The amount of the substance having a fibrous structure is 0.1 to 10 parts by weight of the inorganic pigment having a particle size of 0.1 μm or less.
3. The electrophotographic photoreceptor according to claim 1, wherein the electrophotographic photoreceptor is contained in an amount of 1 to 5 parts by weight. 4. The electrophotographic photosensitive member according to claim 1, wherein the binder resin of the undercoat layer comprises an alkyd resin and a melamine resin. 5. The electrophotographic photoreceptor according to claim 1, wherein the charge generation material contained in the charge generation layer is Y-type oxytitanyl phthalocyanine. 6. The charge transport layer represented by the following general formula:
A charge transport material having a structure
An electrophotographic photosensitive device according to any one of claims 1 to 5,
body. Embedded image(Where R₁, R_Two, R_ThreeAnd R_FourIs a hydrogen atom,
Or unsubstituted lower alkyl group, substituted or unsubstituted
Represents a reel group, Ar₁Is a substituted or unsubstituted aryl
Ar represents a group_TwoRepresents a substituted or unsubstituted arylene group
And Ar₁And R ₁May together form a ring, and
n is an integer of 0 or 1. ) 7. An electrophotographic method in which at least charging, image exposure, development, transfer, cleaning, and charge elimination are repeatedly performed on an electrophotographic photosensitive member, wherein the electrophotographic photosensitive member is used.
7. An electrophotographic method according to any one of claims 1 to 6. 8. A process cartridge for an electrophotographic apparatus comprising at least an electrophotographic photosensitive member, wherein the electrophotographic photosensitive member is any one of claims 1 to 6. Process cartridge for electrophotographic devices.