JP2000089487A - Electrophotographic photoreceptor and electrophotographic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an S-shaped photoreceptor having high performance and excellent electrophotographic characteristics, and to provide a digital electrophotographic device using the photoreceptor. SOLUTION: This electrophotographic photoreceptor has a photosensitive layer containing at least a charge producing material and a charge transfer medium on a conductive substrate. The charge transfer medium 9 contains particles having an electric inactive part 8, and the surface of the electrically inactive part 8 has one or more recesses 8A. The particles having the electric inactive part may consist of only the electrically inactive part or may have a charge transfer part and electrically inactive part.

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 at least a photosensitive layer such as a conductive substrate, a charge generation layer and a charge transport layer provided on a conductive substrate, and more particularly to an electrophotographic photosensitive member suitable for digital electrophotography. It relates to a photoreceptor for photography. The present invention
Further, the present invention relates to a digital electrophotographic apparatus using these electrophotographic photosensitive members.

[0002]

2. Description of the Related Art In recent years, electrophotographic technology has played a central role in the fields of copiers, printers, facsimiles, and the like because of its advantages such as high speed and high printing quality. 2. Description of the Related Art As an electrophotographic photoreceptor used in the electrophotographic technology, a photoconductor using an inorganic photoconductive material such as selenium, a selenium-tellurium alloy, or a selenium-arsenic alloy has been widely known. On the other hand, research on electrophotographic photoreceptors using organic photoconductive materials, which have advantages in terms of cost, manufacturability, disposability, etc., compared with these inorganic photoreceptors, has also become active. It has surpassed the body. In particular, with the development of a photoreceptor having a function-separated type lamination structure in which photocharge generation and charge transport are assigned to separate layers, the degree of freedom in material selection has been increased, and significant improvements in performance have been achieved. At present, this function-separated and laminated organic photoconductor is the mainstream of electrophotographic photoconductors. The charge generation layer in the function-separated laminated organic photoreceptor is formed by directly depositing a pigment having a charge generation ability such as a quinone pigment, a perylene pigment, an azo pigment, a phthalocyanine pigment, or selenium by vapor deposition or the like. Alternatively, those having a high concentration dispersed in a binder resin have been put to practical use. On the other hand, as the charge transport layer, a material in which a low-molecular compound having a charge transport ability such as a hydrazone compound, a benzidine compound, an amine compound, or a stilbene compound is molecularly dispersed in an insulating resin is used.

Conventionally, as a photoconductor used in an analog type electrophotographic copying machine that optically forms an image of a document on a photoconductor and exposes the same, the reproducibility of halftones based on density gradation is improved. Therefore, as shown in FIG.
A photoreceptor having a light-induced potential decay characteristic, that is, a photoreceptor that attenuates the potential in proportion to the amount of exposure (hereinafter, referred to as a photoreceptor)
It is called "J-shaped photoreceptor". ) Is required. The above-mentioned inorganic photoreceptors and organic photoreceptors of the function-separated laminated type all exhibit photoinduced potential decay characteristics falling within this category. However, digital electrophotographic devices, which are being actively researched and developed in response to recent demands for higher image quality, higher added value, networking, etc., generally have an area in which gradation is obtained at an area ratio of dots or the like. Since the gradation method is adopted, the potential does not attenuate until a certain amount of exposure is reached as shown in FIG. 2, and a sharp potential attenuates when the amount of exposure exceeds the so-called S-shaped light-induced potential decay. It is desirable to use a photoreceptor having characteristics (hereinafter, referred to as an “S-shaped photoreceptor”) from the viewpoint of increasing the sharpness of pixels.

The S-shaped photo-induced potential decay characteristic is already known in a single-layer type photoreceptor in which an inorganic pigment such as ZnO and an organic pigment such as phthalocyanine are dispersed in an insulating resin as particles [for example, R. K. M. Schaffert: "El
electrophotography ", Focal P
ress, p. 344 (1975); W. Weig
1, J .; Mammino, G .; L. Whitake
r, R. W. Radler, J .; F. Byrne: "C
current Problems in Electr
ophotography ", Walter de G
ruyter, p. 287 (1972)]. In particular, many proposals have been made for a single-layer photoreceptor for laser exposure in which a phthalocyanine-based pigment having photosensitivity in the near infrared region, which is a transmission wavelength of a semiconductor laser that is widely used at present, is dispersed in a resin [for example, Nguyen Chan K, Aizawa;
“Journal of the Chemical Society of Japan” p. 393 (1986);
169454, 2-207258, and 3
JP-A-31847 and JP-A-5-313387]. However, in these single-layer photoreceptors, although it is necessary for a single material to perform both functions of charge generation and charge transport, materials having excellent performance in both functions are rare.
Nothing that can be put to practical use has yet been obtained. In particular, pigments used as charge generation materials generally have many trap levels, and therefore have drawbacks such as low charge transport ability and residual charges, and are not suitable for charge transfer. On the other hand, when a charge-transporting material is added to improve the charge-transporting property, there is a problem that the S-shaped photoinduced potential decay characteristic decreases and the J-shaped photoinduced potential decay characteristic becomes.

On the other hand, there has been proposed a single-layer type positively charged electrophotographic photosensitive member in which charge generating particles in which a charge generating material is dispersed in an insulating resin medium are dispersed in a photosensitive layer containing a charge transporting material. (JP-A-6-202349). However, in this photoreceptor, since the pigment, which is a charge generating material, has both functions of generating charge and imparting an S-shaped photoinduced potential decay characteristic, instability due to pigment trapping and the like is caused. There is a problem and it is not enough.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances in the prior art, and has a novel S-shaped photoreceptor which can overcome the above problems. It is intended to provide.

That is, an object of the present invention is to provide an electrophotographic photosensitive member having a photosensitive layer, for example, a charge generation layer and a charge transport layer, provided on a conductive substrate. Is to provide the body. It is another object of the present invention to provide a digital electrophotographic apparatus using a high-performance S-shaped photoreceptor.

[0008]

The object of the present invention is to provide particles having an electrically inactive portion in a charge transporting medium of a photosensitive layer, wherein one or more particles are provided on the surface of the electrically inactive portion. This can be achieved by incorporating particles having recesses. Therefore, the electrophotographic photosensitive member of the present invention
On a conductive substrate, a photosensitive layer containing at least a charge generating material and a charge transporting medium is provided, and the charge transporting medium contains particles having an electrically inactive portion. At least one or more concave portions are present on the surface of the electrically inactive portion. In the present invention, the photosensitive layer may have a single-layer structure, but a charge generation layer containing a charge generation material and a charge transport layer containing particles having an electrically inactive portion in a charge transport medium. Preferably, it is composed of Further, the particles having the electrically inactive portion may be composed of only the electrically inactive portion, or may be composed of the charge transport portion and the electrically inactive portion. Good.

Further, an electrophotographic apparatus according to the present invention includes the above electrophotographic photoreceptor and an exposing means for performing exposure based on a digitally processed image signal.

FIGS. 3 and 4 show a charge transport layer as an example of the photosensitive layer in the present invention, and schematically show a cross section of a charge transport medium containing particles having an electrically inactive portion. FIG. FIG. 3 shows a case where the particle is composed of only the electrically inactive portion 8, where one or more concave portions 8A are present on the surface of the electrically inactive portion, and the particle has a charge transporting property. The charge transport layer is formed by being dispersed in the conductive medium 9. FIG. 4 shows that the particles are composed of an electrically inert part 8 and a charge transporting part 10, and
One or more concave portions 8A exist at the interface between the surface of the electrically inactive portion and the charge transporting portion, and these particles are dispersed in the charge transporting medium 9 to form a charge transporting layer. are doing.

Although the mechanism of action in the electrophotographic photosensitive member is not always clear, it is presumed as follows. The reason why the electrophotographic photosensitive member shows an S-shaped potential decay curve is considered to be due to the existence of a spatial trap in the charge transport path. The spatial trap is a portion where the charge transporting portion is convex in the direction in which the charge is to be transported, and acts as a trap only when an electric field is applied. The presence of a large number of such spatial traps is the key to creating an S-shaped photoinduced potential decay characteristic (PIDC). On the other hand, it is necessary to form a continuous phase without separating and isolating the charge transport portion in order to maintain good charge transportability, and the separation and isolation of the charge transport portion increases the residual potential. In addition, problems such as a decrease in light sensitivity and a decrease in charge transport speed occur.

According to the present invention, the particles having one or more concave portions on the surface of the electrically inactive portion are contained in the charge transporting medium, so that the electric charge is stored in the concave portions of the electrically inactive portion. There is a portion where the transport portion enters and becomes convex, and there is a probability that the charge transport portion has a convex portion in the charge transport direction. It is considered that the convex portion acts as a spatial trap, thereby exhibiting an S-shaped potential decay curve. Further, since the charge transporting medium is used, the charge transporting portion is not divided or isolated as in the case where the charge transporting particles are dispersed. Accordingly, it is possible to provide an electrophotographic photoreceptor that exhibits a S-shaped potential decay curve without having a problem such as an increase in residual potential, a decrease in photosensitivity, and a decrease in charge transport speed, having good charge transportability. it can.

In the present invention, the term “recess” refers to a shape in which the periphery of the dent is higher than the bottom, and does not mean a groove or a straight cylindrical shape. For example, the shape is such that when water is poured, the shape is accumulated without spilling, and does not mean a shape that flows down to a lower part like a valley. In addition, even in irregular particles generated by pulverization or the like, such concave portions exist with a certain probability, but the probability is usually quite low, and it is effective to show an S-shaped potential decay curve. There is no. Therefore, in the present invention, irregular particles formed by pulverization are not included as particles having concave portions in the electrically inactive portion.

The charge transporting medium is a solid solution film in which a charge transporting material is dispersed in a binder resin, or a charge transporting polymer film itself having a charge transporting property. A substance having a substantially homogeneous structure for charge transport.

It should be noted that the transport inactive level is far from the transport energy level of the main transport charge from the electrical inactivity referred to here, and that the transport charge may be substantially injected at a normal electric field intensity. Rather, it is effectively in an electrically insulating state for the main charge.

The S-shaped scale of the photo-induced potential decay curve includes:
For example, the ratio E50% / E10% of the exposure amount E50% required to attenuate the charging potential by 50% to the exposure amount E10% required to attenuate the charging potential by 10% can be used. When the potential decay is proportional to the exposure amount in an ideal J-shaped photoreceptor, E50
% / E10% The value is 5. In a general J-shaped photoreceptor,
As the electric field intensity decreases, the charge generation efficiency and / or the charge transport ability decrease, and E50% / E10% shows a value exceeding 5. On the other hand, in the ultimate S-shaped photo-induced potential decay curve in which the potential does not attenuate at all up to a certain exposure amount, but abruptly decreases to the residual potential level at that exposure amount, E50%
/ E10% value is 1. Therefore, S-shaped is E50%
/ E10% Value is defined as being in the range of 1-5.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, each layer constituting the electrophotographic photosensitive member of the present invention will be described in more detail. The photosensitive layer of the electrophotographic photoreceptor of the present invention may have a single-layer structure or a laminated structure including a charge generation layer and a charge transport layer. In the following description, the case of the laminated structure will be mainly described.

FIGS. 5 to 8 are schematic views showing cross sections of an example of the electrophotographic photosensitive member of the present invention. In FIG. 5, a charge generation layer 1 for generating photocharges is provided on a conductive support 3, and particles having an electrically inactive portion thereon are provided on the surface of the electrically inactive portion. The charge transport layer 5 containing one or more concave portions (hereinafter, simply referred to as “particles having concave portions in electrically inactive portions”) is provided. In FIG. 6, an undercoat layer 4 is further provided between the conductive support 3 and the charge generation layer 1. In FIG. 7, a charge generation layer 1 for generating photocharges is provided on a conductive support 3, and a charge transport layer containing particles having a concave portion in an electrically inactive portion for forming an S-shape thereon. 5 is further provided thereon, and a charge transport layer 6 containing no particles having a concave portion in an electrically inactive portion that performs smooth charge transport is provided thereon, and these form the charge transport layer 2. In FIG. 8, an undercoat layer 4 is further provided between the conductive support 3 and the charge generation layer 1.

FIGS. 9 to 11 are schematic views showing cross sections of an electrophotographic photosensitive member according to another embodiment of the present invention. In FIG. 9, a charge transport layer 5 containing particles having a concave portion in an electrically inactive portion is provided on a conductive support 3, and a charge generation layer 1 is provided thereon. In FIG.
A charge transport layer 6 containing no particles having concave portions in the electrically inactive portion is provided on the conductive support 3, and a charge transport layer 5 containing particles having concave portions in the electrically inactive portion is provided thereon. And a charge generation layer 1 is further provided thereon. In FIG. 11, an undercoat layer 4 is further provided between the conductive support 3 and the charge transport layer 6 containing no particles having a concave portion in an electrically inactive portion.

FIGS. 12 and 13 are schematic views showing cross sections of an electrophotographic photosensitive member according to another embodiment of the present invention. FIG.
In the above, a photosensitive layer 7 containing a charge generating material, a charge transporting material, and particles having a concave portion in an electrically inactive portion is provided on a conductive support 3. In FIG.
Further, an undercoat layer 4 is provided between the conductive support 3 and the photosensitive layer 7 containing a charge generating material, a charge transporting material, and particles having a concave portion in an electrically inactive portion. These electrophotographic photoreceptors can further include a protective layer and / or a diffuse reflection layer, if desired.

An intermediate layer may be provided between the charge generating layer and the charge transporting layer containing the particles having concave portions in the electrically inactive portions for the purpose of injecting charges and generating charges. it can. Further, in order to obtain a desired imperfect S-shaped property, particles having a concave portion in an electrically inactive portion between a charge generation layer and a charge transporting layer containing particles having a concave portion in an electrically inactive portion are used. It is also possible to insert a charge transport layer not containing.

The conductive support can be opaque or substantially transparent, and can be aluminum, nickel,
Metals such as chromium and stainless steel, and conductivity-imparting agents such as aluminum, titanium, nickel, chromium, stainless steel, gold, vanadium, tin oxide, indium oxide, plastic films provided with thin films such as ITO, glass, etc. Examples include coated or impregnated paper, plastic films, and glass. These conductive supports can be used in a suitable shape such as a drum shape, a sheet shape, and a plate shape, but are not limited thereto. Further, if necessary, various treatments can be performed on the surface of the conductive support within a range that does not affect the image quality. For example, oxidation treatment, chemical treatment, coloring treatment, or the like, or irregular reflection treatment such as graining can be performed on the surface.

Further, one or more undercoat layers may be provided between the conductive support and the photoconductive layer. The undercoat layer serves as an adhesive layer that prevents the injection of electric charge from the conductive support to the photosensitive layer when the photosensitive layer is charged, and that integrally holds the photosensitive layer on the conductive support. Or, in some cases, the effect of preventing reflection of light from the conductive support.

As the undercoat layer, known ones can be used. For example, polyethylene resin, acrylic resin, methacrylic resin, polyamide resin, vinyl chloride resin, vinyl acetate resin, phenol resin, polycarbonate resin, polyurethane resin, Polyimide resin, vinylidene chloride resin, polyvinyl acetal resin, vinyl chloride
Vinyl acetate copolymer, polyvinyl alcohol resin, water-soluble polyester resin, alcohol-soluble nylon resin,
Resins such as nitrocellulose, casein, gelatin, polyglutamic acid, starch, starch acetate, amino starch, polyacrylic acid, polyacrylamide and copolymers of monomers constituting these resins, and zirconium alkoxide compounds, titanium alkoxide compounds, silane cups A curable metal organic compound such as a ring agent can be used alone or in combination of two or more. Further, a material capable of transporting only charges having the same polarity as the charged polarity can be used.

The thickness of the undercoat layer is 0.01 to 10
μm is appropriate, and preferably in the range of 0.05 to 5 μm. As a coating method, a blade coating method,
Wire bar coating method, spray coating method,
Conventional methods such as a dip coating method, a bead coating method, an air knife coating method, and a curtain coating method can be used.

The photosensitive layer of the electrophotographic photosensitive member of the present invention contains at least a charge generating material, a charge transporting material, and particles having a concave portion in an electrically inactive portion. In particular, particles having a concave portion in an electrically inactive portion need to be dispersed in a charge transporting medium containing a charge transporting material. Examples of the charge transporting medium containing the charge transporting material include a solid solution film in which a low molecular weight charge transporting material is dispersed in a binder resin, and a polymer compound having a self-charge transporting brain.

As the charge generating material for the photosensitive layer of the electrophotographic photosensitive member of the present invention, a known material used for a charge generating layer of a conventional J-shaped laminated photosensitive member can be used. For example, amorphous selenium, selenium-tellurium alloy, selenium-arsenic alloy, other selenium compounds and selenium alloys,
Inorganic photoconductive materials such as zinc oxide, titanium oxide, a-Si, a-SiC, phthalocyanine, squarium,
Organic pigments and dyes such as anthrone-based, perylene-based, azo-based, anthraquinone-based, pyrene-based, pyrylium salts, and thiapyrylium salts can be used, but are not limited thereto. These organic pigments and dyes can be used alone or in combination of two or more.

The phthalocyanine-based compound has a wavelength of 60 nm, which is the emission wavelength of LEDs and laser diodes which are currently used as a light source in digital electrophotographic apparatuses.
Since it has excellent photosensitivity at 0 to 850 nm, it is particularly preferable as the charge generation material of the present invention. Specifically, it is a metal-free phthalocyanine, a metal phthalocyanine compound, and the central metal of the metal phthalocyanine is Cu, Ni, Z
n, Co, Fe, V, Si, Al, Sn, Ge, Ti,
Examples include In, Ga, Mg, Pb, and the like, and oxides, hydroxides, halides, alkylates, and alkoxylates of these central metals can also be used. Specific examples include metal-free phthalocyanine, titanyl phthalocyanine, chlorogallium phthalocyanine, hydroxygallium phthalocyanine, vanadyl phthalocyanine, chloroindium phthalocyanine, dichlorotin phthalocyanine, and the like. Further, those having an arbitrary substituent in these phthalocyanine rings can also be used.
Further, those in which an arbitrary carbon atom in these phthalocyanine rings is substituted with a nitrogen atom are also effective. As the form of these phthalocyanine compounds, it is possible to use amorphous or all polymorphic forms.

Among these phthalocyanine compounds,
Titanyl phthalocyanine, chlorogallium phthalocyanine, hydroxygallium phthalocyanine, and dichlorotin phthalocyanine have particularly excellent photosensitivity and are particularly preferred as charge generation materials.

Further, while most phthalocyanine compounds have the property of a p-type semiconductor in which holes are the main transport charge, dichlorotin phthalocyanine is an n-type semiconductor in which the electron is the main transport charge. have. Therefore, an S-shaped photoreceptor containing dichlorotin phthalocyanine as a charge generation material, and a charge generation layer and a charge transport layer sequentially laminated on a conductive substrate, has high sensitivity and Positive charge injection from a conductive base material is suppressed, and good electrophotographic characteristics are obtained with low dark decay and high chargeability.

Hexagonal selenium can also be preferably used as a charge generation material because of its excellent charge generation efficiency.
The beam diameter of the laser beam can be reduced as the transmission wavelength becomes shorter.Therefore, the aim of further improving the image quality is to reduce the wavelength of the exposure laser, but the photosensitive area of hexagonal selenium is limited. , 680 nm or less, hexagonal selenium can be particularly preferably used as a charge generation material for short-wavelength lasers in this range.

The charge generation layer can be prepared by vacuum deposition of the charge generation material or by dispersing or dissolving the charge generation material in a binder resin.
Examples of the binder resin used for the charge generation layer include polyvinyl butyral resin, polyvinyl formal resin, partially modified polyvinyl acetal resin, polycarbonate resin, polyester resin, acrylic resin, polyvinyl chloride resin, polystyrene resin, polyvinyl acetate resin, and vinyl chloride-acetic acid. Examples include, but are not limited to, vinyl copolymers, silicone resins, phenolic resins, poly-N-vinylcarbazole resins, and the like. These binder resins can be block, random or alternating copolymers. These binder resins may be used alone or
A mixture of more than one species can be used.

The mixing ratio (volume ratio) of the charge generating material and the binder resin is preferably in the range of 10: 1 to 1:10. More preferably, it is set in the range of 3: 1 to 1: 1. When the compounding ratio of the charge generation material to the binder resin is larger than the above range, dark decay is increased and mechanical properties are deteriorated. If the amount is less than the above range, problems such as a decrease in photosensitivity and an increase in residual potential occur. In general, the thickness of the charge generation layer used in the present invention is suitably from 0.05 to 5 μm, and preferably from 0.1 to 2.0 μm. As a coating method, a usual method such as a blade coating method, a wire bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method, a curtain coating method, or the like can be used.

The photosensitive layer containing particles having concave portions in the electrically inactive portion is formed by applying a liquid in which particles having concave portions in the electrically inactive portion are dispersed in a charge transporting medium. Can be. In the present invention, various types of particles having concave portions in the electrically inactive portion can be used. As a first embodiment, particles composed of only electrically inactive portions and having one or more concave portions on the surface can be used. As a first specific example of a particle composed of only an electrically inactive portion and having one or more concave portions on the surface, silicon oxide, aluminum oxide, aluminum hydroxide, titanium oxide, zirconium oxide, magnesium oxide, etc. Particles obtained by fixing the inorganic fine particles as secondary particles by sintering or the like. The particle diameter of the inorganic fine particles before the sintering treatment is preferably in the range of 0.01 to 0.5 μm, and after sintering is preferably in the range of 0.1 to 10 μm.

Composed of only electrically inactive parts,
As a second specific example of the particles having one or more concave portions on the surface, there can be mentioned particles made of a porous polymer material, that is, porous polymer particles. The porous polymer particles are prepared by a suspension polymerization method using a mixture of a monomer and a solvent of the monomer and a non-solvent of the polymer, and forming a droplet of the polymer and the solvent and the non-solvent of the polymer in an appropriate medium. It can be produced by a known method such as a method of removing only the solvent. In addition, the soluble fine particles are dispersed in a medium containing an insulating binder resin, and pulverized, spray-dried, salted out, coacervated, cosolventized, solvent removed, etc. It can also be produced by a method of dispersing in a dispersion medium, forming particles by a method such as a suspension polymerization method or an emulsion polymerization method, and then dissolving and removing only soluble particles. These porous polymer particles can be crosslinked. These particles can be subjected to a surface treatment such as a hydrophobic treatment and a hydrophilic treatment. Porous polymer particles include styrene, methacrylic, acrylic,
It is preferable to be composed of a resin such as vinyl acetate, and the pore size is preferably in the range of 0.01 to 0.5 μm.

As a second embodiment of the particle having a concave portion in the electrically inactive portion, the particle is constituted by a charge transporting portion and an electrically inactive portion, and one or more particles are provided on the surface of the electrically inactive portion. Particles having concave portions can be used. In this case, as a first specific example, there can be mentioned particles in the form of single or plural charge transporting fine particles dispersed in an electrically inert polymer medium. Particles in the form of single or multiple charge-transporting fine particles dispersed in an electrically inert polymer medium are obtained by dispersing the charge-transporting fine particles in a medium containing an insulating binder resin and pulverizing the particles. Method, spray-drying method, salting-out method, coacervation method, solvent removal method or the like, or charge-transporting fine particles are dispersed in a monomer, and suspension polymerization method, emulsion polymerization method or the like is used. It can be manufactured by forming particles. As the charge transporting fine particles, known particles can be used. For example, benzidine compounds, amine compounds, hydrazone compounds, stilbene compounds, hole transporting low molecular weight compounds such as carbazole compounds, fluorenone compounds, malononitrile compounds, electron transporting low molecular weight compounds such as diphenoquinone compounds, A polymer compound having a group having charge transport ability such as polyvinylcarbazole in a side chain; a polymer compound having a group having charge transport ability in a main chain as disclosed in JP-A-5-232727; And particles of a polymer compound or the like having a charge transporting property itself such as polysilane. The charge transporting polymer particles described in Japanese Patent Application No. 8-315235 have solvent resistance and can be preferably used. Furthermore, inorganic fine particles having charge transporting ability such as zinc oxide and amorphous silicon particles can also be used. These charge transporting fine particles have a particle size of 1
The content is preferably in the range of 30.01 to 0.5 μm, and its content in the polymer medium is preferably in the range of 5 to 60% by weight.

As a second specific example of a particle composed of a charge transporting portion and an electrically inactive portion and having one or more concave portions on the surface of the electrically inactive portion, a particle having a high charge transporting property is described. Particles composed of a mixture of a molecular compound and an electrically inactive polymer compound, wherein the charge transporting polymer compound and the electrically inactive polymer compound are in a phase-separated state can be given. Particles composed of a mixture of a charge transporting polymer compound and an electrically inactive polymer compound, and in which the charge transporting polymer compound and the electrically inactive polymer compound are in a phase separated state, By mixing or kneading a charge-transporting polymer compound and an electrically inactive polymer compound, and forming particles by a pulverization method, a spray-drying method, a salting-out method, a coacervation method, a solvent removal method, or the like. Can be manufactured.

A third specific example of a particle comprising a charge transporting portion and an electrically inactive portion and having one or more concave portions on the surface of the electrically inactive portion includes a charge transporting portion. Particles comprising a copolymer of a block and an electrically inactive block, wherein the charge transporting block and the electrically inactive block are in a phase-separated state can be given.
Particles composed of a copolymer of a charge transport block and an electrically inactive block, and in which the charge transport block and the electrically inactive block are in a phase separated state, are incompatible with each other. A block copolymer or a graft copolymer comprising a charge transporting block and an electrically inactive block is formed into particles by a pulverization method, a spray drying method, a salting out method, a coacervation method, a solvent removal method, or the like. It can be manufactured by the following.

As a fourth specific example of a particle composed of a charge-transporting portion and an electrically inactive portion, and having one or more concave portions on the surface of the electrically inactive portion, a particle having a charge-transporting portion may be used. The part is made of a polymer in which the charge transporting material is dissolved,
Particles in which the electrically inactive portion is made of an electrically inactive polymer can be used. The particles in which the charge-transporting portion is made of a polymer in which the charge-transporting material is dissolved, and the particles in which the electrically inactive portion is made of the electrically inactive polymer are polymers that are compatible with the charge-transporting material. Mixing or kneading a mixture of a charge-transporting material and a polymer that is incompatible with the charge-transporting material, and granulating by pulverization, spray-drying, salting-out, coacervation, solvent removal, etc. Can be manufactured. Also, a mixture of a polymer having compatibility with the charge transporting material and a polymer having compatibility with the charge transporting material is mixed or kneaded, and a pulverizing method is used.
Spray dry method, salting out method, coacervation method, after particle formation by solvent removal method, etc., or immers the formed particles in a solution in which the charge transporting material is dissolved, or directly,
Manufacturing by dissolving the charge transport material in a polymer portion compatible with the charge transport material, such as by dispersing in a solution in which the charge transport material and the binder resin are dissolved to form the charge transport layer. Can be.

A fifth specific example of a particle which is composed of a charge transporting portion and an electrically inactive portion, and has one or more concave portions on the surface of the electrically inactive portion, includes a charge transporting material. And particles made of a copolymer of an electrically inactive block in which the charge transporting material is not dissolved and a block in which the charge transporting material is dissolved. Particles composed of a copolymer of a block in which the charge transporting material is dissolved and an electrically inactive block in which the charge transporting material is not dissolved are formed of an electrically inactive block compatible with the charge transporting material. Mixing or kneading a mixture of a block copolymer or a graft copolymer of an electrically inactive block incompatible with the charge transporting material and the charge transporting material, pulverizing method, spray drying method, salting out It can be manufactured by forming particles by a method, a coacervation method, a solvent removal method, or the like. Also,
Mixing or kneading a mixture of an electrically inactive block that is compatible with the charge transporting material and an electrically inactive block that is incompatible with the charge transporting material, and pulverizing, spray drying, and salting out methods After the particles are formed by a coacervation method, a solvent removal method, or the like, the obtained particles are immersed in a solution in which the charge transporting material is dissolved, or directly, with a charge transporting material for forming a charge transporting layer. It can also be produced by dissolving or impregnating the charge transporting material in the block portion compatible with the charge transporting material, for example, by dispersing in a liquid in which the binder resin is dissolved.

In the above case, the polymer compound used for the particles can be cross-linked by a known method before, simultaneously with, or after forming the particles. Cross-linking facilitates the particle formation process, facilitates the dispersion process, stabilizes the dispersion, increases the range of choices for the solvent for forming the charge transport layer, and prevents the charge transport material from being mixed into the electrically inactive portion. Desired effects such as prevention occur. These particles can be subjected to a surface treatment such as a hydrophobic treatment and a hydrophilic treatment. By performing the surface treatment, desirable effects such as facilitation of the dispersion step and stabilization of the dispersion are produced.

As the polymer compound or block constituting the electrically inactive portion used for the particles in the present invention, a known insulating polymer compound or block can be used. For example, as a high molecular compound, polycarbonate resin, polyarylate resin, polyester resin, polysulfone resin, acrylic resin, methacrylic resin such as polymethyl methacrylate resin, polyethylene resin, polyamide resin, vinyl chloride resin, vinyl acetate resin, phenol resin, polyurethane Resin, styrene resin, polyimide resin, vinylidene chloride resin, polyvinyl acetal resin, vinyl chloride-vinyl acetate copolymer, polyvinyl alcohol resin, water-soluble polyester resin, alcohol-soluble nylon resin, nitrocellulose, casein, gelatin, polyglutamic acid, Resins such as starch, starch acetate, amino starch, polyacrylic acid, polyacrylamide and copolymers of monomers constituting these resins, or zirconium alcohol Sid compound,
Curable metal organic compounds such as a titanium alkoxide compound and a silane coupling agent can be used alone or in combination of two or more. Examples of the block include those made of monomers constituting these resins.

The charge-transporting polymer compound or block constituting the charge-transporting portion used for the particles may be a polymer compound having a charge-transporting group such as polyvinylcarbazole in the side chain, or the like. Kaihei 5-232727
And high-molecular compounds having a group having a charge transporting ability in the main chain thereof, and polysilanes, as disclosed in Japanese Patent Application Laid-Open No. H10-260, and the like. In the present invention, the charge transporting polymer compound or block preferably contains a triarylamine structure in the molecule, and the triarylamine structure is represented by the following general formula (1) or (2). A polymer compound or block containing at least one or more of the following structures as a repeating unit is particularly preferred.

[0044]

Embedded image

(Wherein, Ar ₁ and Ar ₂ each independently represent a substituted or unsubstituted aryl group, and X ₁ represents a divalent hydrocarbon group having an aromatic ring structure or a heteroatom-containing hydrocarbon. X ₂ and X ₃ each independently represent a substituted or unsubstituted arylene group; and L ₁ represents a divalent hydrocarbon group or a hetero atom-containing hydrocarbon group which may have a branched or ring structure. Where m and n are
Each means an integer selected from 0 or 1. )

Embedded image (In the formula, Ar ₃ and Ar ₄ each independently represent a substituted or unsubstituted aryl group, and L ₂ represents a trivalent hydrocarbon group having an aromatic ring structure or a heteroatom-containing hydrocarbon group.)

In the general formula (1), Ar ₁ and Ar ₂
Are each independently selected from a substituted or unsubstituted aryl group, and specific examples of the aryl group include a phenyl group, a biphenyl group, a naphthyl group, and a pyrenyl group. Examples of the substituent include a methyl group, an ethyl group, a methoxy group, and a halogen atom.

X ₁ is selected from a divalent hydrocarbon group having an aromatic ring structure or a heteroatom-containing hydrocarbon group.
Specific examples include a phenylene group, a biphenylene group, a terphenylene group, a naphthylene group, a methylenediphenyl group,
Cyclohexylidene diphenyl group, oxydiphenyl group, thiodiphenyl group and the like, and methyl-substituted, ethyl-substituted, methoxy-substituted, and halogen-substituted thereof, and among them, a substituted or unsubstituted biphenylene group is particularly preferred. It is particularly preferable in terms of charge transportability.

X ₂ and X ₃ are each independently selected from a substituted or unsubstituted arylene group.
Examples thereof include a phenylene group, a biphenylene group, a terphenylene group, a naphthylene group and the like, and a methyl-substituted, ethyl-substituted, methoxy-substituted or halogen-substituted form thereof.

L ₁ is selected from a divalent hydrocarbon group or a hetero atom-containing hydrocarbon group which may have a branched or ring structure, and is arbitrarily selected as long as it exhibits at least one of the above-mentioned preferable characteristics. However, those having a bonding group selected from an ether bond, an ester bond, a carbonate bond, a siloxane bond and the like and having 20 or less carbon atoms are preferable. Specific examples include the following.

[0050]

Embedded image

In the above general formula (2), Ar ₃ and Ar ₄
Are each independently selected from a substituted or unsubstituted aryl group, and specific examples of the aryl group include a phenyl group, a biphenyl group, a naphthyl group, and a pyrenyl group. Examples of the substituent include an alkyl group or an alkoxy group having 1 to 12 carbon atoms, a diarylamino group, and a halogen atom.

L ₂ is selected from a trivalent hydrocarbon group having an aromatic ring structure or a heteroatom-containing hydrocarbon group, and is arbitrarily selected as long as it exhibits at least one of the preferable characteristics described above. Those having a number of 20 or less are preferred.
Specific examples include the following.

[0053]

Embedded image

The particle having a concave portion in the electrically inactive portion is composed of a charge transporting portion and an electrically inactive portion, and the particle having one or more concave portions on the surface of the electrically inactive portion. Among them, particles composed of a polymer compound having a phase separation structure have a phase separation structure in which the charge transporting part becomes islands and the electrically inactive part becomes sea, so that the charge transporting property of the electrically inactive part becomes This is advantageous because the interface with the portion is easily formed as a concave portion. In addition, such a phase separation structure has a volume ratio of the charge transporting portion and the electrically inactive portion of 60/60.
It is preferably in the range of 40 to 5/95, and more preferably in the range of 40/60 to 20/80.

In the present invention, the particles having concave portions in the electrically inactive portion have a particle size of 20 nm to 1 in weight average.
The range is preferably 0 μm, more preferably 30 nm to 5 μm.
μm, more preferably in the range of 50 nm to 2 μm. If the particle diameter of the particles having the concave portion in the electrically inactive portion is smaller than the above range, the depth of the concave portion becomes shallow, the concave portion does not effectively act as a spatial trap, and the S-shaped property deteriorates. On the other hand, if it is larger than the above range, the surface properties and uniformity of the photoreceptor are deteriorated. The depth of the concave portion present on the surface of the electrically inactive portion of the particle having the concave portion in the electrically inactive portion,
The range is preferably from 10 nm to 1 μm, more preferably 2 nm.
0 nm to 500 nm, more preferably 30 nm to 20 nm
The range is 0 nm. If the depth of the concave portion is smaller than the above range, the concave portion does not effectively act as a spatial trap, and the S-shaped property is deteriorated. On the other hand, if it is deeper than the above range, the probability that the trapped charges will be detrapped becomes low, so that problems such as a decrease in charge transport ability and an increase in residual potential occur.

The volume resistivity of the electrically inactive portion of the particles is preferably 10 ¹³ Ω · cm or more, more preferably 10 ¹⁴ Ω · cm or more. When the volume resistivity is lower than this value, the electrical insulation of the electrically inactive portion is impaired, and the S-character tends to be lost. When the electrically inactive portion is formed from a polymer block, the volume resistivity of a homopolymer having a structure similar to that of the block can be expressed as the volume resistivity of the electrically inactive portion. .

As the charge transporting medium of the charge transporting layer containing particles having a concave portion in an electrically inactive portion, a conventional J.P.M.
A known material used as a charge transport layer in a letter-shaped laminated photoreceptor can be used. For example, benzidine compounds, amine compounds, hydrazone compounds, stilbene compounds, hole transporting low molecular weight compounds such as carbazole compounds or fluorenone compounds, malononitrile compounds, electron transporting low molecular weight compounds such as diphenoquinone compounds. , Alone or as a mixture of two or more of them, a solid solution film in which molecules are uniformly dispersed in an insulating resin such as polycarbonate, polyarylate, polyester, polysulfone, and polymethyl methacrylate, or charge transport having its own charge transport ability A high molecular compound or the like can be used. Examples of the charge-transporting polymer compound include a polymer compound having a group having a charge-transporting ability such as polyvinylcarbazole in a side chain and having a charge-transporting ability as disclosed in JP-A-5-232727. Examples include a polymer compound having a group in the main chain, and polysilane.

In the present invention, it is particularly preferable to use a charge transporting polymer compound as the charge transporting medium. It is for the following reasons. That is, when the electrically inactive portion of the particles contains a polymer, by contacting the low-molecular charge-transporting material, the low-molecular charge-transporting material is compatible with the electrically inactive portion, When mixed, the electrically inactive portion is no longer electrically inactive and has a charge transporting property, which causes deterioration of the S-shaped property. Further, when the amount is small and the charge transporting property is not exhibited, the charge transporting material functions as an energetic charge trap, which causes an increase in residual potential and the like. Of course, this problem can be solved by carefully selecting the material so that the high molecular compound or block of the electrically inactive portion and the low molecular compound charge transporting material in the charge transporting medium are not compatible. Can be avoided, but this greatly imposes restrictions on the choice of material, making it difficult to achieve compatibility with other characteristics. However, it is known that polymer compounds are hardly compatible with each other, and it is generally known that phase separation occurs. When a charge transporting polymer compound is used as a charge transporting medium, an electrically inactive portion is Even if contains a polymer compound, the charge-transporting polymer compound and the polymer compound of the electrically inactive portion phase-separate,
The charge-transporting material is not mixed into the electrically inactive portion, and the disadvantage such as the case where the low-molecular-weight charge-transporting material is included does not occur.

The charge transporting polymer compound as the charge transporting medium preferably contains a triarylamine structure in the molecule, and further has a structure represented by the above general formula (1) or (2). A polymer compound containing at least one of the above as a repeating unit is particularly preferred.

In the present invention, the content of the particles having concave portions in the electrically inactive portions in the photosensitive layer is preferably in the range of 10 to 70% by weight, more preferably in the range of 20 to 60% by weight, and further preferably. Ranges from 30 to 50% by weight. If the content of the particles having the concave portions in the electrically inactive portion is less than 10% by weight, the absolute number of the spatial traps becomes insufficient, and a photoconductor exhibiting a sufficient S-shaped potential decay characteristic cannot be obtained. On the other hand, when the content is more than 70% by weight, the coating properties deteriorate.

In the present invention, the thickness of the charge transporting layer containing particles having a concave portion in the electrically inactive portion is 0.1 mm.
The range of 1 to 50 μm is appropriate, preferably 0.2 to 50 μm.
It is set to 15 μm, more preferably in the range of 0.5 to 5 μm. If the thickness is smaller than the above range, the S-character tends to be lost. The upper limit of the film thickness is limited by the charge transporting ability of the S-shaped charge transporting layer to be used, and the response speed, the residual potential, and the like are set within allowable ranges.

Further, by adding a compound capable of transporting only a charge having a polarity opposite to that of a main transport charge to a charge transport layer containing particles having a concave portion in an electrically inactive portion,
Effects such as a decrease in residual potential and improvement in repetition stability can also be obtained. In particular, it is preferable to include it in an electrically inactive portion. As a coating method, a usual method such as a blade coating method, a wire bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method, a curtain coating method, or the like can be used.

As the charge transport layer containing no particles having a concave portion in the electrically inactive portion, a known charge transport layer used as a charge transport layer in a conventional J-shaped laminated photoreceptor can be used. For example, benzidine compounds, amine compounds, hydrazone compounds, stilbene compounds,
Hole transporting low molecular weight compounds such as carbazole compounds or fluorenone compounds, malononitrile compounds,
A solid solution in which an electron-transporting low-molecular compound such as a diphenoquinone-based compound is dispersed alone or in a mixture of two or more thereof in an insulating resin such as polycarbonate, polyarylate, polyester, polysulfone, and polymethyl methacrylate. A film or a high molecular compound having a charge transporting ability by itself can be used. Further, an inorganic substance having a charge transporting ability, such as selenium, amorphous silicon, or amorphous silicon carbide, can also be used. Examples of the charge transporting polymer compound include a polymer compound having a charge transporting group such as polyvinylcarbazole in a side chain, and a group having a charge transporting function as disclosed in JP-A-5-232727. And a polysilane having a main chain of

In the present invention, it is preferable to use a charge-transporting high molecular compound from the viewpoint of production as the charge transport layer containing no particles having a concave portion in the electrically inactive portion. It is for the following reasons. That is, when a charge transport layer containing particles having concave portions in the electrically inactive portion and a charge transport layer not containing particles having concave portions in the electrically inactive portion are formed into a laminated film, the concave portions are formed in the electrically inactive portion. When the charge-transporting low-molecular compound is used for the charge-transporting layer that does not contain the particles having, the charge-transporting low-molecular compound is mixed into the charge-transporting layer containing the particles having the concave portions in the electrically inactive portion, and the S-shape is impaired due to a decrease in the insulating property of the inactive portion against the main charge, or obstacles such as an increase in the residual potential, a decrease in the transport ability, and a decrease in the photosensitivity due to the trapping of the contaminating molecules. appear. This problem is particularly noticeable when each layer is formed by a wet coating method. Of course, these problems can be solved by choosing a coating solvent for the upper layer that does not easily dissolve and swell the lower layer,
Alternatively, it can be avoided by selecting an electrically inactive portion that is incompatible with the charge transporting low molecular weight compound. However, it is known that it is common for polymers to undergo phase separation without being compatible with each other, and the electrically inactive portion is used as a charge transport layer containing no particles having one or more concave portions. When a charge transporting polymer compound is used, the phase separation is performed without being compatible with the electrically inactive portion of the charge transport layer containing the particles having the concave portions in the electrically inactive portion. This has the advantage that the problem of contamination hardly occurs and the restrictions on the selection of materials and manufacturing methods are eliminated.

For the above reason, in the case of a charge transporting layer comprising a charge transporting polymer compound and having no particles having a concave portion in an electrically inactive portion, a molecular weight of 10
It is desirable that the charge transporting compound of not more than 00 is not contained in 5% or more.

Further, as the charge-transporting polymer compound of the charge-transporting layer which does not contain particles having concave portions in the electrically inactive portion, at least one kind of the structure represented by the above general formula (1) or (2) Is particularly preferred because it has a high charge transporting ability and excellent mechanical properties.

In the present invention, an electrically inactive region surrounded by a charge transporting matrix may be present in the charge transporting layer containing no particles having concave portions in the electrically inactive portion. For example, reducing surface friction, reducing wear,
Alternatively, insulating particles and the like can be contained for the purpose of reducing surface deposits and the like. In addition, the charge transport layer containing no particles having a concave portion in the electrically inactive portion can contain charge transporting fine particles and the like in order to improve charge transport ability.

The thickness of the charge transport layer containing no particles having concave portions in the electrically inactive portion used in the present invention is from 1 to 50.
μm, preferably in the range of 5 to 30 μm. As a coating method, a usual method such as a blade coating method, a wire bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method, a curtain coating method, or the like can be used. In addition, those capable of vapor phase film formation can be directly formed by a vacuum evaporation method or the like. In the present invention, the total thickness of the entire charge transport layer is generally 5 to 10
The range of 0 μm is appropriate, preferably 10 to 50 μm
Is set in the range.

When the charge transporting layer is present between the charge generating layer and the exposure light source, it is desirable that the charge transporting layer is practically transparent to light of the exposure wavelength in order to prevent a decrease in effective photosensitivity. Preferably, the transmittance of light used for exposure in the charge transport layer is 50% or more. It is more preferably at least 70%, further preferably at least 90%. However, if use at low sensitivity is desired, a charge transport layer that is substantially absorptive to light at the exposure wavelength can be used to adjust the effective light sensitivity.

A protective layer may be further provided on the photosensitive layer having a single-layer structure or the photoconductive layer composed of the charge generation layer and the charge transport layer, if necessary. This protective layer protects the photoconductive layer from chemical stress such as ozone and oxidizing gas generated from the charging member, ultraviolet light, etc., or mechanical stress caused by contact with the developer, paper, cleaning member, etc. And
It is effective to improve the substantial life of the photoconductive layer. In particular, the effect is remarkable in the case of having a layer configuration in which a thin charge generation layer is used as an upper layer.

The protective layer is formed by including a conductive material in a suitable binder resin. Examples of the conductive material include metallocene compounds such as dimethylferrocene, antimony oxide,
Materials such as metal oxides such as tin oxide, titanium oxide, indium oxide, and ITO can be used, but not limited thereto. As the binder resin, polyamide, polyurethane, polyester, polycarbonate,
Polystyrene, polyacrylamide, silicone resin,
Known resins such as a melamine resin, a phenol resin, and an epoxy resin can be used. Also, a conductive inorganic film such as amorphous carbon can be used as the protective layer.

The electric resistance of the protective layer is 10 ⁹ to 10 ¹⁴ Ω · c.
The range of m is preferred. When the electric resistance is higher than this range, the residual potential increases. On the other hand, when the electric resistance is lower than this range, the charge leakage in the creeping direction cannot be ignored, and the resolution decreases. The thickness of the protective layer is suitably in the range of 0.5 to 20 μm, and is preferably set in the range of 1 to 10 μm.

When a protective layer is provided, a blocking layer for preventing leakage of electric charge from the protective layer to the photosensitive layer can be provided between the photosensitive layer and the protective layer, if necessary. As the blocking layer, a known layer can be used as in the case of the protective layer.

In the electrophotographic photosensitive member of the present invention, ozone or oxidizing gas generated in the electrophotographic apparatus, or light,
An antioxidant, a light stabilizer, a heat stabilizer, and the like can be added to each layer or the uppermost layer for the purpose of preventing deterioration of the photoconductor due to heat. As the antioxidant, known compounds can be used, for example, hindered phenol, hindered amine, paraphenylenediamine, hydroquinone, spirochroman, spiroidanone and derivatives thereof, organic sulfur compounds such as thioethers, and phosphites And the like.

As the light stabilizer, known ones can be used. For example, derivatives such as benzophenone, benzotriazole, dithiocarbamate, and tetramethylpiperidine, and electrons capable of deactivating the photoexcited state by energy transfer or charge transfer. Examples thereof include an attractive compound and an electron donating compound. Further, insulating particles such as a fluororesin may be dispersed in the outermost surface layer for the purpose of reducing surface wear, improving transferability, improving cleanability, and the like.

As the electrophotographic apparatus equipped with the electrophotographic photosensitive member of the present invention, any apparatus using an electrophotographic method may be used. In particular, an exposing means for exposing based on a digitally processed image signal is used. An electrophotographic apparatus provided is preferred. An electrophotographic apparatus equipped with an exposure unit that performs exposure based on a digitally processed image signal is a light source such as a laser or an LED, and is binarized or pulse-width modulated or intensity-modulated to emit multi-valued light. It is an electrophotographic apparatus for exposing, and examples thereof include an LED printer, a laser printer, a laser exposure type digital copying machine, a liquid crystal shutter type printer and the like. Further, the apparatus unit may be combined with one or more of a cleaning unit, a charging unit, and a developing unit together with the electrophotographic photosensitive member. The E50% / E10% value of the S-shaped photoreceptor is 5 or less. To exhibit favorable digital characteristics, E50% / E
Preferably, the 10% value is less than 3. More preferably, the value is less than 2.

[0077]

The present invention will be specifically described below with reference to examples. However, the present invention is not limited to the following embodiments, and can be appropriately modified. Example 1 A zirconium alkoxide compound (trade name: Organix ZC540, trade name) was placed on an aluminum substrate having a thickness of 1 mm.
A solution consisting of 10 parts by weight of Matsumoto Pharmaceutical Co., Ltd., 1 part by weight of a silane compound (trade name: A1110, manufactured by Nippon Unicar Co., Ltd.), 40 parts by weight of isopropanol, and 20 parts by weight of butanol was applied by a dip coating method. The coating was dried by heating for 1 minute to form an undercoat layer having a thickness of 0.1 μm.

Next, the Bragg angles (2θ ± 0.2 °) of the X-ray diffraction spectrum using CuKα as a radiation source are strong at least at 7.4 °, 16.6 °, 25.5 ° and 28.3 °. 4 parts by weight of chlorogallium phthalocyanine microcrystals having a diffraction peak were mixed with a vinyl chloride-vinyl acetate copolymer (trade name: UCAR Solution Vinyl Resin VMC)
H, manufactured by Union Carbide) 2 parts by weight, xylene 67
Parts of butyl acetate and 33 parts by weight of butyl acetate, and the mixture was dispersed with glass beads by a paint shake method for 2 hours. The obtained coating solution was applied on the undercoat layer by a dip coating method. After heating and drying for 10 minutes, a charge generation layer having a thickness of 0.5 μm was formed.

Next, a polycarbonate Z resin having a molecular weight of 40,000 (trade name: Iupilon Z-400, manufactured by Mitsubishi Gas Chemical Company)
4.8 parts by weight and the following formula (3)

Embedded image In a solution prepared by dissolving 3.2 parts by weight of the low-molecular charge transporting material shown in (1) in 92 parts by weight of monochlorobenzene, kaolin fine powder is subjected to calcination treatment and aminosilane as particles having concave portions composed of only electrically inactive portions. Particles obtained by performing a surface treatment (TRANSLINK555, EN
(Manufactured by GELHARD Co.) was added, and the mixture was dispersed with glass beads for 1 hour using a paint shaker. The resulting dispersion was applied on the charge generation layer by an applicator method, and dried by heating at 115 ° C. for 1 hour to form a charge transport layer having a thickness of 15 μm. As a result, an electrophotographic photoreceptor having a charge transport layer in which particles having a concave portion in an electrically inactive portion were dispersed in a charge transport medium in which a low-molecular charge transport material was dissolved in a binder resin was produced. .

The particles obtained by subjecting the above-mentioned kaolin fine powder to the calcination treatment and the aminosilane-based surface treatment are agglomerated in the course of the calcination treatment and the aminosilane-based surface treatment, and the interface between the particles is appropriately fused. It is considered that the gap between the particles is filled and the concave portion is formed in the particles. The average particle size of the particles is 0.1.
8 μm, the volume resistivity when pressed is 1 × 10 ¹³ Ωc
m or more.

The electrophotographic photoreceptor thus obtained was subjected to an electrostatic copying paper tester (electrostatic analyzer EPA-8100, manufactured by Kawaguchi Electric Works).
Under the environment of normal temperature and normal humidity (20 ° C., 40% RH),
Evaluation of electrophotographic properties was performed. After adjusting the corona discharge voltage and charging the surface of the photoreceptor to -750 V, the halogen lamp light monochromatized to 750 nm through an interference filter was adjusted to have a light intensity of ² mW / m ² on the surface of the photoreceptor. For 7 seconds to obtain a photoinduced potential decay. From this photoinduced potential decay curve, the value of E50% was 7 mJ / m ² ,
The% / E10% value was calculated to be 2.8. The potential after 7 seconds from light irradiation was defined as a residual potential. The residual potential was -80V.

Example 2 In the same manner as in Example 1, up to the charge generation layer was formed. Next, the following formula (4) having a weight average molecular weight of 110,000

Embedded image 15 parts by weight of a charge transporting polymer compound comprising a repeating unit represented by the following formula are dissolved in 80 parts by weight of toluene, and porous styrene-divinyl is formed as particles having only concave portions on the surface and composed of only electrically inactive portions. 5 parts by weight of benzene copolymer particles (trade name: Shodex KF-806, manufactured by Showa Denko KK) were added, and the dispersion obtained by stirring for 24 hours was dip-coated on the charge generation layer, and then 115 ° C. For 30 minutes to form a charge transport layer having a thickness of 30 μm. As a result, an electrophotographic photoreceptor having a charge transport layer in which particles having a concave portion in an electrically inactive portion were dispersed in a charge transport medium composed of a polymer charge transport compound was prepared. The porous styrene-divinylbenzene copolymer particles had an average particle diameter of 5 μm and a pore size of 0.1 μm. The electrophotographic properties of the electrophotographic photoreceptor obtained as described above were evaluated in the same manner as in Example 1. As a result, the E50% value was 5.4 mJ / m ² , and the E50% / E50% / E
The 10% value was 3.1 and the residual potential was -50V.

Example 3 <Preparation of Particles Having Charge-Transporting Fine Particles Dispersed in an Electrically Inactive Polymer Medium> Charge transport comprising a repeating unit represented by the above formula (4) having an OH group at the end. 20 g of the water-soluble polymer compound was dissolved in 150 g of toluene, and 3.0 g of a 3 mol adduct of trimethylolpropane / xylidene diisocyanate (trade name: Takenate D110N, manufactured by Takeda Pharmaceutical Co., Ltd.) was added to prepare an oily layer mixture. 80 kg using 1.0 kg of a 1.0% aqueous solution of polyvinyl alcohol.
After emulsifying and dispersing at a rotation speed of 00 rpm, toluene is removed at normal pressure for 3 hours in a high-temperature bath at 60 ° C., washed with distilled water and lyophilized to form a crosslinked polymer having an average particle size of 0.2 μm. Thus, 20 g of the obtained charge transporting polymer particles were obtained. Next, 20 g of the charge transporting polymer particles and 50 g of styrene monomer
Then, 10 g of divinylbenzene and 1.5 g of benzoyl peroxide as a polymerization initiator were added and dispersed to prepare an oily layer mixture. After performing emulsification and dispersion at a rotation speed of 8000 rpm using 1.0 kg of a 1.0% aqueous solution of polyvinyl alcohol, polymerization was performed for 5 hours in a high-temperature bath at 70 ° C.
After washing with distilled water, freeze-drying was performed to obtain particles in which charge transporting fine particles were dispersed in an electrically inert polymer medium. The average particle size was 2 μm.

<Production of Photoreceptor> A layer up to the charge generation layer was formed in the same manner as in Example 1. Next, 10 parts by weight of the above-described charge-transporting fine particles dispersed in an electrically inactive polymer medium are mixed with the above-mentioned formula (4) having a weight average molecular weight of 110,000.
Is dispersed in a solution obtained by dissolving 15 parts by weight of a charge-transporting polymer compound composed of a repeating unit represented by the following formula in 80 parts by weight of toluene, and then dip-coated on the charge generation layer,
The resultant was dried by heating at 115 ° C. for 30 minutes to form a charge transport layer having a thickness of 30 μm. Thus, an electrophotographic photoreceptor having a charge transport layer in which particles having a concave portion in an electrically inactive portion were dispersed was produced. The electrophotographic properties of the electrophotographic photosensitive member obtained as described above were evaluated in the same manner as in Example 1. As a result, the E50% value was 5.9 mJ / m ² , and the E50% value was E50% / E10%.
The value was 2.5 and the residual potential was -40V.

Comparative Example 1 An electrophotographic photosensitive member was produced in the same manner as in Example 1, except that particles having a concave portion in an electrically inactive portion were not added.
The electrophotographic characteristics of the obtained electrophotographic photoreceptor were measured in Example 1.
As a result of evaluation in the same manner as above, the E50% value was 3.5 mJ / m ² ,
The E50% / E10% value was 5.3 and the residual potential was -20 V. Comparative Example 2 An electrophotographic photosensitive member was produced in the same manner as in Example 3, except that particles having a concave portion in an electrically inactive portion were not added.
The electrophotographic characteristics of the obtained electrophotographic photoreceptor were measured in Example 1.
As a result of evaluation in the same manner as above, the E50% value was 3.1 mJ / m ² ,
The E50% / E10% value was 5.5, and the residual potential was -15 V.

Example 4 An electrophotographic photosensitive member was prepared in the same manner as in Example 3 except that an aluminum drum having a roughened surface was used instead of the aluminum substrate, and a laser printer (Laser printer) was used.
Press 4105, manufactured by Fuji Xerox Co., Ltd.) to perform a printing test. FIG. 14 shows a schematic configuration diagram of this laser printer.

The photosensitive drum 11 is mounted on a laser printer as an apparatus unit together with the charging scorotron 13 and the cleaning blade 17. A pre-exposure light source (red LED) 1 is provided around the photosensitive drum 11.
2, charging scorotron 13, exposure laser optical system 1
4, a developing unit 15, a transfer corotron 16 and a cleaning blade 17 are sequentially arranged in a process order. The exposure laser optical system 14 has a transmission wavelength of 780 nm.
And emits light based on digitally processed image signals. The emitted laser light is configured to expose the photoreceptor while being scanned by a polygon mirror, a plurality of lenses, and a mirror. Reference numeral 18 denotes a sheet.

Comparative Example 3 An electrophotographic photosensitive member was prepared in the same manner as in Comparative Example 2 except that an aluminum drum was used instead of the aluminum substrate, and a printing test was performed in the same manner as in Example 4.

When the quality of the prints obtained in Example 4 and Comparative Example 3 was compared, the print quality of Example 4 was superior in terms of reproducibility of fine lines and the like.

[0090]

As described above, the electrophotographic photoreceptor of the present invention exhibits an S-shaped photoinduced potential decay characteristic because it contains particles having one or more concave portions in the electrically inactive portion. Becomes In addition, the electrophotographic photoreceptor of the present invention has a smaller increase in the residual potential than the conventional S-shaped photoreceptor, and has a reduced charge transport path such as a decrease in photosensitivity and a decrease in charge transport speed. There is no obstruction due to the above, and it has a good S-shaped property. Further, the electrophotographic apparatus using the S-shaped electrophotographic photoreceptor of the present invention can obtain a printed image having excellent print quality and image quality by performing exposure based on a digitally processed image signal.

[Brief description of the drawings]

FIG. 1 is a graph showing a relationship between an exposure amount and a surface potential in a J-shaped electrophotographic photosensitive member.

FIG. 2 is a graph showing a relationship between an exposure amount and a surface potential in an S-shaped electrophotographic photosensitive member.

FIG. 3 is a schematic view showing an example of a charge transport layer containing particles having a concave portion in an electrically inactive portion composed only of an electrically inactive portion in the present invention.

FIG. 4 is a schematic view of a charge transporting layer showing an example having a charge transporting portion and an electrically inactive portion in the present invention and containing particles having a concave portion in the electrically inactive portion.

FIG. 5 is a schematic sectional view showing an example of the electrophotographic photoreceptor of the present invention.

FIG. 6 is a schematic cross-sectional view illustrating an example of the electrophotographic photoconductor of the present invention.

FIG. 7 is a schematic cross-sectional view illustrating an example of the electrophotographic photoconductor of the present invention.

FIG. 8 is a schematic cross-sectional view illustrating an example of the electrophotographic photoconductor of the present invention.

FIG. 9 is a schematic cross-sectional view illustrating an example of the electrophotographic photosensitive member of the present invention.

FIG. 10 is a schematic cross-sectional view illustrating an example of the electrophotographic photosensitive member of the present invention.

FIG. 11 is a schematic cross-sectional view illustrating an example of the electrophotographic photoconductor of the present invention.

FIG. 12 is a schematic cross-sectional view illustrating an example of the electrophotographic photoconductor of the present invention.

FIG. 13 is a schematic sectional view showing an example of the electrophotographic photoreceptor of the present invention.

FIG. 14 is a schematic configuration diagram of an electrophotographic apparatus of the present invention that performs exposure based on digitally processed image signals used in Examples.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Charge generation layer, 2 ... Charge transport layer, 3 ... Conductive support
4 an undercoat layer, 5 a charge transport layer containing particles having a concave portion in an electrically inactive portion, 6 a charge transport layer containing no particles having a concave portion in an electrically inactive portion, 7 a charge generating material, A photosensitive layer containing a charge transporting material and particles having concave portions in an electrically inactive portion, 8... An electrically inactive portion, 8
A: concave portion, 9: charge transporting medium, 10: charge transporting portion, 11: photosensitive drum, 12: light source for pre-exposure, 13 ...
Scorotron for charging, 14 ... Laser optical system for exposure, 1
5: developing device, 16: transfer corotron, 17: cleaning blade, 18: paper.

Claims (10)

[Claims] 1. An electrophotographic photosensitive member having a photosensitive layer containing at least a charge generating material and a charge transporting medium on a conductive substrate, wherein the charge transporting medium has an electrically inactive portion. An electrophotographic photosensitive member containing particles, wherein one or more concave portions are present on the surface of the electrically inactive portion. 2. The photosensitive layer according to claim 1, wherein the photosensitive layer comprises a charge generating layer containing a charge generating material and a charge transporting layer containing particles having an electrically inactive portion in a charge transporting medium. Electrophotographic photoreceptor. 3. The electrophotographic photoreceptor according to claim 1, wherein the particles having the electrically inactive portion are composed of only the electrically inactive portion. 4. The electrophotographic photoreceptor according to claim 1, wherein the particles having an electrically inactive portion comprise a charge transporting portion and an electrically inactive portion. 5. The electrophotographic photoreceptor according to claim 3, wherein the particles having an electrically inactive portion are secondary particles formed by sintering inorganic fine particles. 6. The electrophotographic photoreceptor according to claim 3, wherein the particles having an electrically inactive portion are particles made of a porous polymer material. 7. The electrophotographic photosensitive member according to claim 4, wherein the particles having an electrically inactive portion are particles obtained by dispersing charge transporting fine particles in an electrically inactive polymer medium. . 8. The method according to claim 1, wherein the charge transporting medium contains a polymer charge transporting material as a main component.
Alternatively, the electrophotographic photosensitive member according to claim 2. 9. The exposure amount required for 50% potential decay is 10%
9. The electrophotographic photosensitive member according to claim 1, wherein the exposure amount is not more than five times the exposure amount required for the potential decay. 10. An electrophotographic apparatus, comprising: the electrophotographic photosensitive member according to claim 1; and an exposure unit for performing exposure based on a digitally processed image signal.