JPH10177262A - Electrophotographic device and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress variation in the electric potential of the exposed part of an electrophotographic photoreceptor between 1st and 2nd image forming cycles and to prevent the occurrence of black spots, white spots and ghost by incorporating an electric charge transferring material selected from among specified triphenylamine compds, and specified N,N,N',N'-tetraphenylbenzidine compds. SOLUTION: An electric charge transferring material selected from among triphenylamine compds, represented by formula I and N,N,N',N'- tetraphenylbenzidine compds. represented by formula II is contained in the electric charge transferring layer of a laminate type electrophotographic photoreceptor. In the formula I, each of R1 -R3 is H, halogen, alkoxy, etc., and each of (k), (m) and (n) is an integer of 0-5. In the formula II, each of R4 -R9 is halogen, hydroxyl, alkoxy or alkyl, each of (e), (f), (g) and (h) is an integer of 0-5 and each of (p) and (q) is an integer of 0-4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to
Forming an electrostatic latent image by performing image exposure and the like, developing the electrostatic latent image by reversal development to form a toner image, transferring the toner image to an intermediate transfer member, and forming the toner image on the intermediate transfer member. The present invention relates to a color copying machine, a color printer, an electrophotographic apparatus such as a color facsimile, and an image forming method for transferring an image to a transfer material such as recording paper.

[0002]

2. Description of the Related Art F. The electrophotographic process according to Carlson's invention is widely used not only in the field of copiers but also in the fields of printers and facsimile machines in recent years because of its advantages such as excellent instantaneousness, good storability and high quality images. It has been widely used and applied in various fields. Basically, the electrophotographic process involves uniformly charging the photoreceptor surface, forming an electrostatic latent image by image exposure corresponding to a document, developing the electrostatic latent image with toner, and transferring the toner image to paper ( (It may be via an intermediate transfer member)
And an image forming process by fixing, and an initialization process by removing toner and electric charge remaining on the surface of the photoconductor, that is, a cleaning process for removing a developer remaining on the surface of the photoconductor, which is performed to repeatedly use the photoconductor. And a static elimination process for removing residual charges.

[0003] As for the photoreceptor which is the core of the electrophotographic process, selenium and arsenic which are conventionally used are known.
Recently, instead of inorganic photoconductive materials such as selenium alloys, cadmium sulfide, and zinc oxide, photoconductors using organic photoconductive materials that have advantages of being non-polluting, easy to form films, easy to manufacture, etc. Is being developed. Among these, a so-called laminated photoconductor in which a charge generation layer and a charge transport layer are laminated has higher sensitivity and a wider selection range of materials,
At present, photoconductors have become the mainstream and are mass-produced because of their high safety, high coating productivity and relatively advantageous manufacturing costs.

In recent years, digitization of image formation has been rapidly progressing in order to obtain higher quality images and to store and freely edit input images. Up to now, digital image forming devices include laser printers, output devices of word processors and personal computers, and LEs.
Although digital printers and some color laser copiers have been limited to digital printers, digital copying has recently been rapidly progressing in ordinary copying machines in which analog image formation has been the mainstream.

When digitally forming an image, when computer information is directly used, an electric signal as the computer information is converted into an optical signal, and when image information of a document is input, the image is converted into an optical signal. After the information is read as optical information, it is once converted to a digital electric signal, converted to an optical signal again, and then input to the photoconductor. In any case, an optical signal is input to the photoreceptor.
Mainly, laser light and LED light are used. Current,
The most frequently used oscillation wavelength of input light is near-infrared light of 780 nm or 660 nm or long-wavelength light close thereto. The first characteristic required for photoreceptors used for digital image formation is high sensitivity to these long-wavelength lights. Studies have been made to determine whether or not it has such characteristics. Among them, phthalocyanine compounds are relatively easy to synthesize, and many of them exhibit high sensitivity to long-wavelength light. Therefore, photoconductors using phthalocyanine compounds have been widely studied and put to practical use.

For example, Japanese Patent Publication No. 5-55860 discloses a photoreceptor using titanyl phthalocyanine.
JP-A-155851 discloses a photoreceptor using β-type indium phthalocyanine, JP-A-2-23369 discloses a photoreceptor using a χ-type metal-free phthalocyanine, and JP-A-61-28557 discloses a vanadyloxy group. Photoreceptors using phthalocyanine are disclosed.

On the other hand, in recent electrophotographic processes, the use of an intermediate transfer member has been actively used, and many image forming apparatuses using the intermediate transfer member have been provided. The intermediate transfer member is a color image forming apparatus or a multicolor image that sequentially stack-transfers a plurality of component color images of color image information or multicolor image information and outputs an image formed product that combines and reproduces the color image or the multicolor image. The present invention is useful for a forming apparatus, a color image forming apparatus, and an image forming apparatus having a multicolor image forming function. By using the intermediate transfer member in these apparatuses, it is possible to improve the superposition of the respective component color images, and to obtain an image free from deviation (color deviation).

In the case of a color electrophotographic apparatus having an image forming apparatus using an intermediate transfer member, a second image carrier is stuck or adsorbed on a transfer drum, and an image on the first image carrier is transferred thereto. It is superior to a color electrophotographic apparatus having an image forming apparatus, for example, described in JP-A-63-301960, in the following points. That is, 1) color misregistration hardly occurs when toner images of each color are superimposed.
2) The second image carrier can be transferred from the intermediate transfer body without any processing or control (for example, gripping by a clipper, adsorbing, imparting a curvature, etc.), and the second image carrier can be transferred. A wide variety of image carriers can be selected. For example, thin paper (40 g / m ² paper) to thick paper (200 g / m ² paper) such as envelopes, postcards, label paper, etc.
The transfer can be performed irrespective of the width of the second image carrier, the length thereof, the thickness thereof, and the thickness thereof. 3) Since the rigidity of the intermediate transfer member is excellent, dimensional accuracy such as dents, distortions, deformations, and the like is less likely to occur due to repeated use, and the frequency of replacement of the intermediate transfer member can be reduced. Due to the above advantages, color copiers, color printers, and the like using an image forming apparatus using an intermediate transfer member have been actively developed recently.

On the other hand, in the case of digitally forming an image, a so-called reversal developing method of forming an image by attaching toner to a portion irradiated with light is used for the purpose of effectively utilizing light or increasing the resolving power. There are many. In the reversal developing method, a dark potential portion becomes a white background, and a bright potential portion becomes a black background portion (image portion). As described above, the photoreceptor after the completion of the image is subjected to an initialization process for forming the next image.
A method using corona discharge, a method using light, and the like are known. Among these, a photostatic method which can be performed by a simple device and does not involve generation of harmful gas such as ozone as in the case of AC corona discharge is often used.

[0010] However, the inventors of the present invention have conducted an image formation using a laminated electrophotographic photosensitive member containing a phthalocyanine compound in a charge generation layer and an intermediate transfer member in a copying process by such reversal development. It was also found that electrons after holes were first injected into the laminated electrophotographic photosensitive layer tended to remain in the charge generating layer, and as a kind of memory there was a drawback that potential fluctuation was apt to occur.

In principle, it is presumed that electrons remaining in the charge generation layer proceed to the interface between the charge generation layer and the charge transport layer for some reason, and lower the barrier property of hole injection near the interface. . Actually, in the case of using a laminated electrophotographic photosensitive member containing a phthalocyanine compound in the charge generation layer, the exposed portion potential in the previous cycle exposure portion in the next cycle exposure region in the next cycle exposure region due to the difference in the presence or absence of exposure in the previous cycle. The potential of the exposed portion rises higher than the surroundings, that is, the potential of the exposed portion rises more than the first cycle in the second cycle, and the potential of the exposed portion fluctuates between the first cycle and the second cycle. Alternatively, the sensitivity at the place where light was applied during the previous cycle is apparently faster, that is, the photosensitivity in the second cycle is increased and the exposed portion potential is lower than that in the first cycle, and between the first cycle and the second cycle. In the next cycle, when a uniform image is taken in the next cycle, the occurrence of the so-called positive ghost phenomenon, in which the previous cycle part appears black, is remarkably observed.

As described above, the laminated photoreceptor for forming a digital image containing a phthalocyanine compound in the charge generation layer is extremely useful, but has a problem that space charges are easily accumulated in the photosensitive layer. One of the causes is
Injection of a reverse polarity charge from the surface of the photosensitive layer can be mentioned. The easiness of injecting the opposite polarity charge from the surface of the photosensitive layer is an inherent problem based on the material of the surface layer of the photoreceptor, and in the case of the laminated type photoreceptor, the material of the charge transport layer and the charge generation layer It is also an inherent problem based on the combination with the material.

An image forming apparatus using an intermediate transfer member is particularly required for a color image forming apparatus which is required to have high definition and excellent color reproduction / resolution and high image quality / high reliability. However, when the transfer of the toner image to the intermediate transfer member is performed by the above-described reversal development process, the primary transfer by the charge having the polarity opposite to the charge is required. In a conventional image forming process, even in a situation where it has been found that a laminated photoreceptor containing a phthalocyanine compound in the charge generation layer is strongly affected by the reverse polarity in the primary transfer, the superimposed transfer to the intermediate transfer member is not performed in the conventional image forming process. In this case, stress of the opposite polarity over several times had to be applied to the laminated photoreceptor.

An electrophotographic apparatus and an image forming method using a lamination type photoreceptor containing a phthalocyanine compound in a charge generation layer and utilizing an image forming process of sequentially transferring toner images formed by reversal development to an intermediate transfer member are described above. In other words, 1) the potential of the exposed portion of the electrophotographic photosensitive member greatly fluctuates between the first cycle and the second cycle; 2)
This phenomenon is further exacerbated and promoted by repeating this development between the first cycle and the second cycle for a long period of time. 3) The opposite polarity charge is injected from the surface of the photosensitive layer so as to be copied. At present, there is a problem that the number of black spots increases. Therefore, development of an electrophotographic apparatus and an image forming method free from such a problem is desired.

[0015]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned conventional problems and to achieve the following objects in response to such a demand. That is, the present invention is directed to an electrophotographic apparatus and an image forming apparatus which have a small variation in the exposed portion potential of the electrophotographic photosensitive member between the first cycle and the second cycle in the image forming process, and do not cause black spots, white spots, or ghosts It is an object to provide a forming method.

[0016]

Means for Solving the Problems Using a laminated electrophotographic photosensitive member containing a phthalocyanine compound in a charge generation layer, a toner image formed on the laminated electrophotographic photosensitive member by reverse development is sequentially transferred to an intermediate transfer member. In order to solve the above-mentioned problems relating to an electrophotographic apparatus and an image forming method using an image forming process, the inventors of the present invention have conducted intensive studies, and as a result, the charge transport layer in the laminated electrophotographic photosensitive member has a specific Triphenylamine compound and N, N, N ', N'-
When a charge transport material selected from a tetraphenylbenzidine compound is contained, resistance to stress due to reverse polarity transfer can be improved, and charges of the opposite polarity can be effectively prevented from being injected from the surface of the photosensitive layer. It has been found. The present invention is based on such findings by the inventors of the present invention.

The means for solving the above problems are as follows. (1) a latent image forming means for forming an electrostatic latent image on a laminated electrophotographic photosensitive member provided with a charge generating layer containing at least a phthalocyanine compound and a charge transporting layer on a conductive support; Reversal developing means for developing the electrostatic latent image to form a toner image by development, first transfer means for transferring the toner image to an intermediate transfer member, and transferring the toner image on the intermediate transfer member to a transfer material In the electrophotographic apparatus comprising a second transfer means, the charge transport layer in the laminated electrophotographic photoreceptor,
It comprises a charge transport material selected from a triphenylamine compound represented by the following general formula (A) and an N, N, N ', N'-tetraphenylbenzidine compound represented by the following general formula (B). An electrophotographic apparatus, characterized in that: General formula (A)

[0018]

Embedded image

(Wherein, in the general formula (A), R ₁ , R ₂ and R ₃ each represent a hydrogen atom, a halogen atom, an alkoxy group, a substituted or unsubstituted saturated or unsaturated aliphatic hydrocarbon group, An unsubstituted aryl group, or
Represents an atomic group necessary for forming a fused polycyclic group by combining with a benzene ring. k, m and n each represent an integer of 0-5. ) General formula (B)

[0020]

Embedded image

(However, in the general formula (B), R ₄ , R ₅ ,
R ₆ , R ₇ , R ₈ and R ₉ are each a halogen atom,
Represents a hydroxyl group, an alkoxy group or an alkyl group. e, f,
g and h each represent an integer of 0-5. p and q
Represents an integer of 0 to 4, respectively. )

(2) The electrophotographic apparatus according to (1), wherein the reversal developing means comprises a plurality of developing units each containing a toner of a different color.

(3) The electrophotographic apparatus according to the above (1) or (2), wherein the phthalocyanine compound is a gallium phthalocyanine halide.

(4) An image forming method, wherein an image is formed using the electrophotographic apparatus according to any one of (1) to (3).

(5) a latent image forming step of forming an electrostatic latent image on a laminated electrophotographic photosensitive member provided with a charge generating layer containing at least a phthalocyanine compound and a charge transporting layer on a conductive support; A reversal development step of developing the electrostatic latent image by reversal development to form a toner image; a first transfer step of transferring the toner image to an intermediate transfer member; and applying the toner image on the intermediate transfer member to a transfer material. In the image forming method including a second transfer step of transferring, the charge transport layer in the laminated electrophotographic photoreceptor includes a triphenylamine compound represented by the general formula (A) and a triphenylamine compound represented by the general formula (B). N, N,
An image forming method comprising a charge transport material selected from N ', N'-tetraphenylbenzidine compounds.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An electrophotographic apparatus according to the present invention comprises a latent image forming means, a reversal developing means, a first transfer means and a second transfer means. The electrophotographic apparatus of the present invention further includes other units such as a fixing unit as necessary. The image forming method of the present invention includes a latent image forming step, a reversal developing step, a first transfer step, and a second transfer step. The image forming method of the present invention comprises:
Further, other steps such as a fixing step are included as necessary. The image forming method of the present invention can be suitably performed using the electrophotographic apparatus of the present invention. Hereinafter, each means or step in the electrophotographic apparatus and the image forming method of the present invention will be described in detail.

(Latent Image Forming Unit and Latent Image Forming Step) The latent image forming unit has a function of forming an electrostatic latent image on the electrophotographic photosensitive member. The latent image forming step is a step of forming an electrostatic latent image on the electrophotographic photosensitive member. The latent image forming step can be suitably performed using the latent image developing unit.

-Electrophotographic Photoreceptor- The electrophotographic photoreceptor may be a single-layer type electrophotographic photoreceptor formed by a deposited film of a charge generating substance.
A function-separated type electrophotographic photoreceptor can be suitably used. Examples of the laminated electrophotographic photoreceptor include those obtained by providing a photosensitive layer such as a charge generation layer (CGL) and a charge transport layer (CTL) on a conductive support. The charge generation layer (CGL) preferably contains at least a phthalocyanine compound. Examples of the material of the conductive support include a metal material such as aluminum, an aluminum alloy, stainless steel, copper, and nickel; a polyester film on which aluminum is deposited; and paper. The conductive support is generally subjected to a honing treatment or the like before the photosensitive layer is provided on the surface thereof.

In the laminated electrophotographic photosensitive member, a known barrier layer may be provided between the conductive support and the photosensitive layer. As the barrier layer, for example, aluminum anodic oxide coating, aluminum oxide, inorganic layer of aluminum hydroxide, etc., polyvinyl alcohol, casein, polyvinylpyrrolidone, polyacrylic acid, celluloses, gelatin, starch, polyurethane, polyimide, polyamide, etc. And the like, a layer made of an organic metal compound such as a silane coupling agent and an organic zirconium, a layer made of a mixture of the aforementioned substances, and the like. The barrier layer may include conductive or semiconductive fine particles such as a metal such as aluminum, copper, tin, zinc, and titanium, or a metal oxide.

The photosensitive layer generally comprises a charge generation layer (C
GL) and a charge transport layer (CTL). The charge generation layer (CGL) includes at least a charge generation material (CGM) and a binder resin. The charge generation material (CGM)
Examples thereof include metal-free phthalocyanines, metals such as indium copper chloride, gallium chloride, tin, oxytitanium, zinc, and panadium or oxides thereof, and phthalocyanine compounds coordinated with chlorides. Among these, in terms of light sensitivity, electrical property stability, image quality, etc., halogenated gallium phthalocyanines such as chlorogallium phthalocyanine, halogenated tin phthalocyanines such as dichlorotin phthalocyanine, hydroxygallium phthalocyanine, oxytitanyl phthalocyanine, and chloroindium phthalocyanine. Preferred are indium phthalocyanine halides, vanadyl phthalocyanine, and the like,
Gallium phthalocyanine halides are particularly preferred. In these phthalocyanine compounds, a plurality of coordinating central metals may be used together in the form of a mixed crystal, or a plurality of them may be mixed as a single product.

The charge generation layer may contain a charge generation material other than the phthalocyanine compound in order to change the spectral sensitivity and to improve the electrical characteristics such as chargeability and residual potential. Such charge generating materials include, for example,
Selenium and its alloys, arsenic-selenium, cadmium sulfide,
Examples include zinc oxide, other inorganic photoconductive substances, azo dyes, quinacridone, polycyclic quinones, bilylium salts, thiavirylium salts, indigo, thioindigo, anthantrone, pyranthrone, and cyanine.

The above-mentioned charge generating substances are fine particles, and the average particle diameter is preferably 1 μm or less, and 0.5 μm or less.
The following is more preferred, and the thickness is particularly preferably 0.3 μm or less.

Examples of the binder resin include polyester resin, polyvinyl acetate, polyacrylate, polymethacrylate, polyester, polycarbonate, polyvinyl acetoacetal, polyvinyl propional, polyvinyl butyral, phenoxy resin, epoxy resin and urethane. Resins, cellulose esters, cellulose ethers and the like can be mentioned.

The charge generation layer is formed by dispersing the fine particles of the charge generation substance in the binder resin. In the charge generation layer, the use ratio of the binder resin and the charge generation substance is generally Is 30 to 500 parts by weight of the charge generating substance based on 100 parts by weight of the binder resin. The thickness of the charge generation layer is usually 0.1 to 2 μm, preferably 0.15 to 0.8 μm. Further, the charge generation layer may contain various additives such as a leveling agent, an antioxidant, and a sensitizer for improving applicability, if necessary.

The charge transport layer (CTL) contains at least a charge transport material (CTM) and a binder resin. In the charge transport layer, the charge transport material is bound to the binder resin. Preferred examples of the charge transport material include a triphenylamine compound represented by the general formula (A) and an N, N, N ′, N′-tetraphenylbenzidine compound represented by the general formula (B). Can be In the present invention, at least one of them can be used as a charge transporting substance. The triphenylamine compound represented by the general formula (A) and the N,
The N, N ', N'-tetraphenylbenzidine compound may be used in combination. Specific examples (A-1 to A-30) of the triphenylamine compound represented by the general formula (A) are shown in Tables 1 to 3 below.
3 is shown.

[0036]

[Table 1]

[0037]

[Table 2]

[0038]

[Table 3]

N, N, N ', N' represented by the general formula (B)
-Specific examples of the tetraphenylbenzidine compound (B-1 to
B-19) is shown in Table 4 below.

[0040]

[Table 4]

In the present invention, other charge transporting substances may be used in addition to those described above as the charge transporting substance. As other charge transporting substances, for example, 2,4,7-
Electron-withdrawing substances such as trinitrofluorenone and tetracyanoquinodimethane, heterocyclic compounds such as carbazole, indole, imidazole, oxazole, pyrazole, oxadiazole, pyrazoline and thiadiazole, aniline derivatives, hydrazone compounds and aromatic amine derivatives , Stilbene derivatives, and electron donating substances such as polymers having a group consisting of these compounds in the main chain or side chain.

Examples of the binder resin include vinyl homopolymers and copolymers such as polymethyl methacrylate, polystyrene and polyvinyl chloride, polycarbonate, polyester, polyester carbonate, polysulfone, polyimide, phenoxy, epoxy and silicone resins. Is mentioned. These may be used alone or in combination of two or more. In the latter case, these may be used as partially crosslinked cured products.

The use ratio of the binder resin and the charge transport material in the charge transport layer is generally 30 parts by weight of the charge transport material with respect to 100 parts by weight of the binder resin.
To 200 parts by weight, preferably 40 to 150 parts by weight. If the amount of the charge transporting material is less than 30 parts by weight based on 100 parts by weight of the binder resin, the mobility is reduced, and the amount of the charge transporting material is 200 parts by weight based on 100 parts by weight of the binder resin.
If the amount exceeds the weight part, the mechanical strength may be reduced.

The thickness of the charge transport layer is generally 5 to 50 μm, preferably 10 to 45 μm. In addition, the charge transport layer may contain well-known additives such as a plasticizer, an antioxidant, an ultraviolet absorber, and a leveling agent in order to improve film formability, flexibility, applicability, and the like.

In the present invention, when viewed from the conductive support side, the charge generation layer (lower layer) and the charge transport layer (upper layer) are formed on the conductive support or on the undercoat layer formed on the surface thereof. These photosensitive layers are laminated in this order or vice versa, and further a known surface protective layer on the surface of the charge transport layer or the charge generation layer, for example, an overcoat layer mainly composed of a thermoplastic or thermosetting polymer. (OCL) or the like may be formed. In the surface protective layer, as in the case of the charge transport layer, a film-forming property, flexibility, a well-known plasticizer for improving coatability, an antioxidant, an ultraviolet absorber, a leveling agent, and the like. An additive may be contained.

The method for forming each of the above-mentioned layers in the layered electrophotographic photoreceptor is not particularly limited, and a known method may be employed depending on the purpose. A method of preparing a coating solution for each layer, which is dissolved or dispersed in a solvent, and sequentially applying and drying this coating solution, may be mentioned.

-Formation of Electrostatic Latent Image- The latent image forming means is not particularly limited as long as it has a function of forming an electrostatic latent image on the electrophotographic photosensitive member. On the other hand, a charging unit for charging, an image exposing unit for imagewise exposing the image, and a latent image forming unit having other units as needed are preferably exemplified. The latent image forming step is not particularly limited as long as an electrostatic latent image can be formed on the electrophotographic photosensitive member,
For example, the electrophotographic photoreceptor may include a charging step of performing charging, an image exposure step of performing imagewise image exposure, and other steps as necessary, and the latent image formation may be performed. It can be suitably performed by means.

The charging means is not particularly limited.
For example, a known charger such as a contact-type charger using a conductive or semi-conductive roller, brush, film, rubber blade, or the like, a scorotron charger using a corona discharge, or a corotron charger may be used. Among these, a contact-type charger is preferable because of its excellent charge compensation ability. The charging unit normally applies a direct current to the electrophotographic photoreceptor, but may apply an alternating current further superimposed. The charging can be suitably performed using the charging unit. The electrophotographic photoreceptor usually has a charge of -300 to
It is charged to -1000V.

The image exposure means is not particularly limited. For example, an optical apparatus capable of exposing a light source such as a semiconductor laser light, an LED light, and a liquid crystal shutter light to the surface of the electrophotographic photosensitive member in a desired image. And the like. The image exposure can be suitably performed using the image exposure unit.

(Reversal Developing Unit and Reversal Developing Step) The reversal developing unit has a function of developing the electrostatic latent image formed on the electrophotographic photosensitive member by reversal development to form a toner image. The reversal development step is a step of developing the electrostatic latent image formed on the electrophotographic photosensitive member by the reversal development to form a toner image. The reversal development step can be suitably performed using the reversal development unit.

-Reversal Development- The reversal development is carried out using a general reversal developing means for developing a magnetic or non-magnetic one-component developer or a two-component developer in contact or non-contact. be able to. Such a reversal developing unit is not particularly limited as long as it has the above-mentioned function, and can be appropriately selected depending on the purpose.For example, the one-component developer or the two-component developer may be used. A known developing device having a function of attaching to the electrophotographic photosensitive member using a brush, a roller, or the like can be used.

(First Transfer Means and First Transfer Step) The first transfer means has a function of transferring a toner image formed on the electrophotographic photosensitive member by reverse development to an intermediate transfer member. The first transfer step is a step of transferring a toner image formed on the electrophotographic photosensitive member by reversal development to an intermediate transfer member. The first transfer step can be suitably performed using the first transfer unit. Hereinafter, the transfer of the toner image to the intermediate transfer member may be referred to as “first transfer”.

The first transfer means is not particularly limited as long as it has the above-mentioned functions. For example, a contact-type transfer charger using a belt, a roller, a film, a rubber blade, or the like, or a corona discharge is used. Known transfer chargers such as a scorotron transfer charger and a corotron transfer charger are known. Among these, a contact-type transfer charger is preferable because of its excellent transfer charge compensation ability. In the present invention, a peeling charger and the like can be used in addition to the transfer charger. In addition, during the first transfer, a direct current is usually used as a transfer current applied from the first transfer unit to the electrophotographic photosensitive member. In the present invention, an alternating current is further superimposed. May be used. The setting conditions in the first transfer unit vary depending on the image area width to be charged, the shape of the transfer charger, the opening width, the process speed (peripheral speed), and the like, and cannot be defined unconditionally.
For example, the primary transfer current is +100 to +400 μm.
A: The primary transfer voltage can be set to +500 to +2000 V.

-Intermediate Transfer Member-The structure of the intermediate transfer member is generally a multilayer structure. For example, an elastic layer formed of at least rubber, elastomer, resin, etc. on a conductive support, And a structure provided with at least one coating layer.
The shape of the intermediate transfer member is not particularly limited and may be appropriately selected depending on the intended purpose. Examples of the shape include a roller shape and a belt shape. In the present invention, among these, color shift at the time of superimposing images,
The endless belt shape is particularly preferable in terms of durability due to repeated use, ease of freedom in arrangement of other subsystems, and the like.

As the material of the intermediate transfer member, for example,
Conductive carbon particles and metal powder for polyurethane resin, polyester resin, polystyrene resin, polyolefin resin, polybutadiene resin, polyamide resin, polyvinyl chloride resin, polyethylene resin, fluorine resin, etc. And the like are preferably used. Among these, those obtained by dispersing carbon particles in a polyurethane resin can be suitably used.

The surface volume resistance of the intermediate transfer member is preferably, for example, 10 ⁸ to 10 ¹⁶ Ωcm. If the surface volume resistance value is less than 10 ⁸ Ωcm, bleeding or thickening occurs in the image, and if it exceeds 10 ¹⁶ Ωcm, scattering of the image occurs, and the need for static elimination of the intermediate transfer body sheet occurs.
Either case is not preferred. The thickness of the intermediate transfer member is preferably, for example, about 50 to 200 μm.

(Second Transfer Means and Second Transfer Step) The second transfer means has a function of collectively transferring the toner image on the intermediate transfer member to a transfer material. The second transfer step is a step of collectively transferring the toner images on the intermediate transfer member to a transfer material. The second transfer step can be suitably performed using the second transfer unit. Hereinafter, the transfer of the toner image to the transfer material may be referred to as “second transfer”.

The second transfer means is not particularly limited as long as it has the above-mentioned functions. For example, the contact type transfer charger, scorotron transfer charger, corotron transfer charger exemplified as the first transfer means And the like. Among these, a contact-type transfer charger is preferable as in the first transfer unit. Further, at the time of the second transfer, the second transfer is performed.
Normally, a direct current is used as the transfer current applied from the transfer unit to the intermediate transfer member. However, in the present invention, an alternating current may be further superimposed and used.

The setting conditions in the second transfer means vary depending on the image area width to be charged, the shape of the transfer charger, the opening width, the process speed (peripheral speed), etc., and cannot be specified unconditionally. +100 to +400 μA as a secondary transfer current, +2 as a primary transfer voltage
000 to +5000 V can be set as the set value.

(Other Means and Other Steps) As the other means, for example, a light discharging means for light discharging the electrophotographic photosensitive member, and a second transfer toner image is fixed on a transfer material. Fixing means; an electrophotographic photosensitive member cleaner for cleaning the electrophotographic photosensitive member; an intermediate transfer member cleaner for cleaning the intermediate transfer member; The other steps can be suitably performed using the other means corresponding to the step, for example, using a light removing means in the case of the light removing step, and using a fixing means in the case of the fixing step.

The light neutralizing means includes, for example, a tungsten lamp and an LED, and the light quality used in the light neutralizing process includes, for example, white light such as a tungsten lamp and red light such as an LED light. Can be The intensity of the irradiation light in the photostatic process is usually several times to 30 times the amount of light indicating the half-reduction exposure sensitivity of the electrophotographic photosensitive member.
The output is set to be about twice.

The fixing means is not particularly limited.
A fixing device known per se, for example, a hot roll fixing device, an oven fixing device and the like can be mentioned.

An example of the electrophotographic apparatus of the present invention and an image forming method of the present invention performed using the electrophotographic apparatus of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic explanatory view showing a first embodiment of an electrophotographic apparatus according to the present invention, showing a monochromatic electrophotographic apparatus. FIGS. 2 to 3 are schematic explanatory diagrams showing a second embodiment of the electrophotographic apparatus according to the present invention and a color electrophotographic apparatus. FIG. 4 is a schematic explanatory view showing a multi-transfer type color electrophotographic apparatus without using an intermediate transfer member.

The electrophotographic apparatus shown in FIG. 1 can be used as a copying machine, a laser beam printer or the like.
The electrophotographic apparatus shown in FIG. 1 includes an electrophotographic photosensitive member 1, a charging unit 2, an image exposure unit 3 (a color separation / imaging exposure optical system for a document image, and a time series electric digital pixel signal for image information. Scanning exposure system using a laser scanner that outputs a modulated laser beam), a reversal developing means 4, an electrophotographic photosensitive member cleaner 5, an intermediate transfer member 6, and a roller 7
, A roller 8, a roller 9, a first transfer unit 10, and a second transfer unit 12.

The electrophotographic photosensitive member 1 is the above-described electrophotographic photosensitive member of the present invention, and has a drum shape. The electrophotographic photoreceptor 1 may be called a photoreceptor drum. The electrophotographic photoreceptor 1 is rotatably provided in an electrophotographic apparatus at a predetermined peripheral speed (process speed) in a clockwise direction of an arrow, and a corona discharge device as a charging unit 2 is provided around the electrophotographic photoreceptor 1. An image exposing unit as the image exposing unit 3, a monochromatic developing unit as the reversal developing unit 4, and an electrophotographic photosensitive member cleaner 5 are arranged.

An endless belt-shaped intermediate transfer member 6 is disposed between the reversal developing means 4 and the electrophotographic photosensitive member cleaner 5. The intermediate transfer member 6 includes three rollers 7 to 9
As a result, the rollers 7 and 8 can rotate in the counterclockwise direction of the arrow at the same peripheral speed as the electrophotographic photosensitive member 1.
Is in contact with the electrophotographic photoreceptor 1. The roller 9 and the transfer roller as the second transfer unit 12 are arranged to face each other, and the recording paper 11 is moved on the interface by these rotational driving forces so as to be in contact with them. A transfer charger as a first transfer unit 10 is disposed at a position inside the intermediate transfer member 6 and opposed to a portion where the intermediate transfer member 6 and the electrophotographic photosensitive member 1 are in contact with each other. I have.

In the electrophotographic apparatus of the first embodiment shown in FIG. 1, the electrophotographic photosensitive member 1 is driven to rotate. In conjunction with this, a corona discharger as the charging means 2 is driven to uniformly charge the surface of the electrophotographic photosensitive member 1 to a predetermined polarity and potential. The electrophotographic photoreceptor 1 having a uniformly charged surface is
Next, the image is exposed imagewise by an image exposing device as the image exposing means 3, and an electrostatic latent image is formed on the surface. These processes correspond to a latent image forming step in the image forming method of the present invention.

Subsequently, the electrostatic latent image is developed by a single-color developing unit as a reversal developing unit 4. Then, a toner image is formed on the surface of the electrophotographic photosensitive member 1. Note that the toner at this time may be a one-component toner or a two-component toner, but is a two-component toner here. These processes correspond to the reversal development step in the image forming method of the present invention.

This toner image is applied to the intermediate transfer member 6 from a transfer charger as a first transfer means 10 to be driven in the process of passing through the interface (nip portion) between the electrophotographic photosensitive member 1 and the intermediate transfer member 6. The primary (intermediate) is sequentially applied to the outer peripheral surface of the intermediate transfer body 6 by the electric field generated by the primary transfer bias.
Transcribed. The electrophotographic photosensitive member 1 to the intermediate transfer member 6
Is applied from a bias power supply with a polarity (+) opposite to that of the toner. The applied voltage is in a range of, for example, +2 kV to +5 kV. This process corresponds to a first transfer step in the image forming method of the present invention.

Thereafter, the toner remaining on the electrophotographic photosensitive member 1 is cleaned and removed by the electrophotographic photosensitive member cleaner 5. Then, the electrophotographic photosensitive member 1 is subjected to the next copy cycle.

On the other hand, the toner image transferred onto the intermediate transfer body 6 is transferred onto the recording paper 11 by the contact charging action of the transfer roller as the second transfer means 12. This process corresponds to the second transfer step in the image forming method of the present invention. As described above, a desired image is formed on the recording paper 11.

The electrophotographic apparatus shown in FIG. 2 can be used as a copying machine, a laser beam printer or the like.
The electrophotographic apparatus shown in FIG. 2 includes an electrophotographic photoreceptor 1, a charging unit 2, and an image exposure unit 3 (a color separation / imaging exposure optical system for a document image, which corresponds to a time-series electric digital pixel signal of image information. And a multi-color developing device including four developing units of a magenta developing device 41, a cyan developing device 42, a yellow developing device 43, and a black developing device 44. Reversal developing means, an electrophotographic photosensitive member cleaner 14,
An intermediate transfer member 6, a first transfer unit 10, an intermediate transfer member cleaner 15, a second transfer unit 12, and a heat roller fixing device as a fixing unit 17 are provided.

The electrophotographic photosensitive member 1 is the above-described electrophotographic photosensitive member according to the present invention, and has a drum shape. The electrophotographic photoreceptor 1 may be called a photoreceptor drum. The electrophotographic photoreceptor 1 is rotatably provided in an electrophotographic apparatus at a predetermined peripheral speed (process speed) in a clockwise direction of an arrow, and a corona discharge device as a charging unit 2 is provided around the electrophotographic photoreceptor 1. An image exposing device as the image exposing device 3, a reversal developing device as a multicolor developing device, and an electrophotographic photosensitive member cleaner 14 are arranged.

An endless belt-shaped intermediate transfer member 6 is disposed between the reversal developing means and the electrophotographic photosensitive member cleaner 14. The intermediate transfer member 6 is rotatable at the same peripheral speed as the electrophotographic photosensitive member 1 in the counterclockwise direction of the arrow by three rollers and a transfer charger as the first transfer unit 10. A part of the intermediate transfer member 6 located on the transfer charger as the electrophotographic photosensitive member 1
Is in contact with The first transfer means 1 among the three rollers;
The roller located adjacent to the transfer charger as 0 and the transfer roller as the second transfer means 12 are arranged to face each other. It moves by force.

In the electrophotographic apparatus of the second embodiment shown in FIG. 2, the electrophotographic photosensitive member 1 is driven to rotate. In conjunction with this, a corona discharger as the charging means 2 is driven to uniformly charge the surface of the electrophotographic photosensitive member 1 to a predetermined polarity and potential. The electrophotographic photoreceptor 1 having a uniformly charged surface is
Next, the image is exposed imagewise by an image exposing device as the image exposing means 3, and an electrostatic latent image is formed on the surface. These processes correspond to a latent image forming step in the image forming method of the present invention.

Subsequently, the electrostatic latent image is developed by reversal developing means as a multicolor developing device. More specifically,
First, development with magenta toner is performed by the magenta developing device 41 of the four developing units provided in the reversal developing means. Next, the reversal developing means rotates,
The cyan developing device 42 moves to a position facing the electrophotographic photosensitive member 1. The cyan developing device 42 performs development using cyan toner. Next, the reversal developing means rotates, and the yellow developing device 43
Move to the position facing. The yellow developing device 43 performs development with yellow toner. Next, the reversal developing means is rotated, and the black developing device 44 is rotated.
Moves to a position facing the electrophotographic photosensitive member 1. Then, the black developing device 44 performs the development using the black toner. As a result, the superimposed transfer using the four color toners is performed, and a composite color toner image corresponding to the target color image is formed on the electrophotographic photosensitive member 1.

The above-described development in four colors is performed independently for each color. While development for one color is not performed, development for other colors is not performed. Color development is not affected by other color developers. Specifically, an electrostatic latent image corresponding to a first color component image (for example, a magenta component image) of a target image is first formed. Next, the magenta developing device 41 develops the electrostatic latent image with magenta toner. At this time, the cyan developing device 4
2. Since the developing units of the yellow developing unit 43 and the black developing unit 44 are in the OFF state, they do not act on the electrophotographic photoreceptor 1, and the image developed with the magenta toner is
Unaffected by 2-44. As described above, development with the four color toners is sequentially performed on the electrophotographic photosensitive member 1. These processes correspond to the reversal development step in the image forming method of the present invention.

This toner image is applied to the intermediate transfer member 6 from a transfer charger as the first transfer means 10 to be driven in the process of passing through the interface (nip portion) between the electrophotographic photosensitive member 1 and the intermediate transfer member 6. The primary (intermediate) is sequentially applied to the outer peripheral surface of the intermediate transfer body 6 by the electric field generated by the primary transfer bias.
Transcribed. The electrophotographic photosensitive member 1 to the intermediate transfer member 6
The primary transfer bias for the sequential superimposition transfer of the four color toner images to the toner is applied from a bias power supply with the polarity (+) opposite to that of the toner. This process corresponds to a first transfer step in the image forming method of the present invention. In this electrophotographic apparatus, the second transfer means 12 and the intermediate transfer member cleaner 15 are moved from the intermediate transfer member 6 when the four-color toner image is transferred from the electrophotographic photosensitive member 1 to the intermediate transfer member 6 in a superimposed manner. Can be separated.

Thereafter, the toner remaining on the electrophotographic photosensitive member 1 is cleaned and removed by the electrophotographic photosensitive member cleaner 14. Then, the electrophotographic photosensitive member 1 is subjected to the next copy cycle.

On the other hand, the composite color toner image superimposedly transferred onto the intermediate transfer member 6 is transferred between the intermediate transfer member 6 and the transfer roller 12 by the contact charging action (transfer bias) of the transfer roller as the second transfer means 12. The image is transferred onto the recording paper 11 which is sequentially supplied from the paper feed cassette 16 to the contact nip at a predetermined timing. This process corresponds to the second transfer step in the image forming method of the present invention.

Next, the recording paper 11 is transferred to a heat roller fixing device as fixing means 17, and inside the fixing device,
The toner image on the recording paper 11 is thermally fixed. From the above,
A desired image is formed on the recording paper 11. After the image formation on the recording paper 11 is completed, the residual toner on the intermediate transfer body 6 is cleaned and removed by the intermediate transfer body cleaner 15.

The electrophotographic apparatus shown in FIG. 3 can be used as a copying machine, a laser beam printer or the like.
The basic configuration of the electrophotographic apparatus shown in FIG.
The same applies to the electrophotographic apparatus shown in FIG. Further, the functions of each unit and the like in the electrophotographic apparatus shown in FIG. 3 are the same as those of the electrophotographic apparatus shown in FIG.

The electrophotographic apparatus shown in FIG. 3 is largely different from the electrophotographic apparatus shown in FIG.
That is, the black developing device 4Bk, the cyan developing device 4C, the magenta developing device 4M, and the yellow developing device 4Y
And the electrophotographic photoreceptor 1, the charging means 2 and the image exposure means 3 are arranged in total of four sets beside the four color developing units. With the electrophotographic apparatus shown in FIG. 3, an image can be formed similarly to the electrophotographic apparatus shown in FIG.

The multi-transfer type color electrophotographic apparatus shown in FIG. 4, which does not use an intermediate transfer member, can be used as a copying machine, a laser beam printer, and the like. The electrophotographic apparatus shown in FIG. 4 includes a neutralizing light lamp as a light neutralizing unit 51 having a function of neutralizing the electrophotographic photoreceptor 1, a transfer charger 53 and a peeling charger 5 functioning as a first transfer unit.
4 and the transfer drum 52 in place of the intermediate transfer member 6, the basic configuration is the same as that of the electrophotographic apparatus shown in FIG. Also, the functions of each unit in the electrophotographic apparatus shown in FIG. 4 are the same as those of the electrophotographic apparatus shown in FIG. The image forming is also performed by the electrophotographic apparatus shown in FIG. 4 similarly to the electrophotographic apparatus shown in FIG.

[0085]

EXAMPLES Examples of the present invention will be described below.
The present invention is not limited to these examples.

Example 1 Production of Electrophotographic Photoreceptor As described in JP-A-2-87154,
Wet honing of the aluminum pipe was performed. That is, a mirror-finished aluminum pipe of 84 mmφ × 340 mm was prepared, and 10 kg of an abrasive (Green Dethic GC # 400, manufactured by Showa Denko KK) was suspended in 40 liters of water using a liquid honing apparatus. The liquid is sent to the gun at a flow rate of liter / minute, and the spraying speed is 60 mm /
At an air pressure of 0.85 kgf / cm ² , the aluminum pipe was axially moved while rotating at 120 rpm to perform wet honing. Then, a conductive support was obtained. Center line average roughness R _a of the conductive support,
It was 0.16 μm.

A mixture of 170 parts of n-butyl alcohol in which 4 parts of polyvinyl butyral resin (Eslec BM-S, manufactured by Sekisui Chemical Co., Ltd.) was dissolved, 30 parts of an organic zirconium compound (acetylacetone zirconium butyrate) and an organic silane compound (γ- (Aminopropyltrimethoxysilane) (3 parts) was mixed and stirred to obtain a coating liquid for forming an undercoat layer. The coating liquid for forming the undercoat layer is coated on the 84 mmφ aluminum conductive support roughened by a honing treatment, air-dried at room temperature for 5 minutes, and then at 50 ° C. for 10 minutes. The temperature of the conductive support was increased, and the support was placed in a constant-temperature and constant-humidity bath at 50 ° C. and 85% RH (open stall at 47 ° C.). Drying was performed at 10 ° C. for 10 minutes. As described above, an undercoat layer was formed on the conductive support.

Next, 15 parts of gallium chloride phthalocyanine as a charge generating substance and vinyl chloride
A mixture comprising 10 parts of a vinyl acetate copolymer resin (VMCH, manufactured by Nippon Unicar) and 300 parts of n-butyl alcohol was dispersed in a sand mill for 4 hours. The obtained dispersion was used as a coating liquid for a charge generation layer, which was dip-coated on the undercoat layer, and dried to form a charge generation layer having a thickness of 0.2 μm.

Then, N, N'-diphenyl-N, N '
-Bis (3-methylphenyl)-[1,1′-biphenyl] -4,4′-diamine (exemplified substance B-1) 4 parts,
6 parts of a bisphenol A polycarbonate resin (molecular weight 40,000) as a binder resin and one exemplified as the antioxidant (the compound having the hindered phenol structural unit in the molecule) (III-114) (trade name: S
umilizer MDP-S; Sumitomo Chemical Co., Ltd.
0.3 parts) was dissolved by adding 80 parts of chlorobenzene. The solution thus obtained was used as a coating solution for a charge transport layer, and this was coated on the charge generation layer and dried to form a charge transport layer having a thickness of 20 μm. Produced.

-Electrophotographic Apparatus- The electrophotographic apparatus of the first embodiment is the above-described electrophotographic apparatus shown in FIG. In the electrophotographic apparatus shown in FIG.
The electrophotographic photosensitive member 1 uses the electrophotographic photosensitive member manufactured as described above.

-Image Formation- An image was formed by using the electrophotographic apparatus of Example 1 and operating it under the following operating conditions. --- Operating conditions--Process speed: 71 mm / sec Primary transfer charger: roller contact type. Diameter 17.8 mm Resistance value: 10 ⁸ Ωcm Transfer current value: ⁸ μA Transfer voltage: +900 V ・ Secondary transfer charger: Roller contact type Resistance value: 10 ⁶ Ωcm Transfer voltage: +3.4 kV In addition, dark portion potential (V _H ) After adjusting the charger conditions so as to be −700 V, the exposure portion potential (V _L ) becomes −200.
The exposure amount was adjusted so as to be V.

-Evaluation- The latent image potential characteristic of the electrophotographic photosensitive member and the image quality of the obtained image were evaluated at 10 ° C. and 20% RH in the following manner. That is, the image quality evaluation / potential measurement was performed on the initial 10 consecutive images, then 100 continuous copies were repeatedly imaged for a total of 10,000 images at intervals of 1 minute rest, and thereafter after resting overnight, the image was again stopped. Image quality evaluation / potential measurement was performed on 10 continuous sheets. Table 5 shows the above results.

Example 2 Example 1 was the same as Example 1 except that the compound exemplified as (A-11) was used as the charge transporting substance instead of the compound exemplified as (B-1). An electrophotographic photoreceptor was prepared in the same manner as in Example 1, and an image was formed using an electrophotographic apparatus in the same manner as in Example 1. In addition, the same evaluation as in Example 1 was performed, and the results are shown in Table 5.

(Example 3) In Example 1, as compound (B-1), the compound 1.
An electrophotographic photosensitive member was prepared in the same manner as in Example 1, except that 5 parts and 2.5 parts of the compound exemplified as (A-11) were mixed and used. An image was formed using the apparatus. In addition, the same evaluation as in Example 1 was performed, and the results are shown in Table 5.

(Comparative Example 1 and Comparative Example 2) An electrophotographic photoreceptor was prepared in the same manner as in Example 1, except that a hydrazone compound having the following structural formula was used as the charge transporting substance. An image was formed using an electrophotographic apparatus in the same manner as in Example 1. In addition, the same evaluation as in Example 1 was performed, and the results are shown in Table 5. However, only in Comparative Example 2, the multi-transfer type color electrophotographic apparatus shown in FIG. 4 was used.

[0096]

Embedded image

Comparative Example 3 The electrophotographic photosensitive member of Comparative Example 3 was the same as the electrophotographic photosensitive member of Example 1 except that only the charge generation layer was formed and formed under the following conditions. That is,
5 parts by weight of a butyral resin [XYHL (manufactured by UCC)] was dissolved in 150 parts by weight of cyclohexanone, and 10 parts by weight of a trisazo pigment shown in Chemical formula 15 was added thereto and dispersed by a ball mill for 48 hours. Further, 210 parts by weight of cyclohexanone was added and dispersed for 3 hours. The solid content was 1.
The mixture was diluted with cyclohexanone to 8% by weight while stirring. The thus-obtained charge-generating-layer coating solution was applied on the intermediate layer, and dried at 130 ° C. for 20 minutes to form a charge-generating layer having a thickness of 0.2 μm. Then, using the obtained electrophotographic photosensitive member, an image was formed using an electrophotographic apparatus in the same manner as in Example 1. In addition, the same evaluation as in Example 1 was performed, and the results are shown in Table 5.

[0098]

Embedded image

[0099]

[Table 5]

[0100]

According to the present invention, the above-mentioned demands can be met, and the above-mentioned conventional problems can be solved. Further, according to the present invention, there is provided an electrophotographic apparatus in which a change in the potential of the exposed portion of the electrophotographic photosensitive member between the first cycle and the second cycle in the image forming process is small, and black and white spots and ghost are not generated. An image forming method can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing a monochromatic electrophotographic apparatus according to a first embodiment of the present invention.

FIG. 2 is a schematic explanatory view showing a color electrophotographic apparatus according to a second embodiment of the present invention;

FIG. 3 is a schematic explanatory view showing a color electrophotographic apparatus according to a third embodiment of the present invention.

FIG. 4 is a schematic explanatory view showing a multi-transfer type color electrophotographic apparatus without using an intermediate transfer member.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 electrophotographic photoreceptor 2 charging means 3 image exposing means 4 reversal developing means 4Bk black developing device 4C cyan developing device 4M magenta developing device 4Y yellow developing device 5 electrophotographic photoreceptor cleaner 6 intermediate transfer member 7 roller 8 roller 9 roller 10 1 transfer means 11 recording paper 12 second transfer means 14 electrophotographic photosensitive member cleaner 15 intermediate transfer body cleaner 16 paper feed cassette 17 fixing means 41 magenta developing device 42 cyan developing device 43 yellow developing device 44 black developing device 51 light removing means 52 Transfer drum 53 Transfer charger 54 Peeling charger

Claims (5)

[Claims] 1. A latent image forming means for forming an electrostatic latent image on a laminated electrophotographic photosensitive member provided with a charge generation layer containing at least a phthalocyanine compound and a charge transport layer on a conductive support; Reversal developing means for developing the electrostatic latent image to form a toner image by development, first transfer means for transferring the toner image to an intermediate transfer member, and transferring the toner image on the intermediate transfer member to a transfer material In the electrophotographic apparatus provided with a second transfer means, the charge transport layer in the laminated electrophotographic photosensitive member is represented by a triphenylamine compound represented by the following general formula (A) and a general formula (B) represented by the following general formula (B) N, N, N ',
An electrophotographic apparatus comprising a charge transport material selected from N'-tetraphenylbenzidine compounds. General formula (A) (However, in the general formula (A), R ₁ , R ₂ and R ₃ each represent a hydrogen atom, a halogen atom, an alkoxy group, a substituted or unsubstituted saturated or unsaturated aliphatic hydrocarbon group,
A substituted or unsubstituted aryl group or an atomic group necessary for forming a condensed polycyclic group by combining with a benzene ring.
k, m and n each represent an integer of 0-5. ) General formula (B) (However, in the general formula (B), R ₄ , R ₅ , R ₆ , R ₇ ,
R ₈ and R ₉ each represent a halogen atom, a hydroxyl group, an alkoxy group or an alkyl group. e, f, g and h are
Each represents an integer of 0 to 5. p and q are each 0
Represents an integer of from 4 to 4. ) 2. The electrophotographic apparatus according to claim 1, wherein the reversal developing means includes a plurality of developing units each containing a toner of a different color. 3. The electrophotographic apparatus according to claim 1, wherein the phthalocyanine compound is a gallium phthalocyanine halide. 4. An image forming method using the electrophotographic apparatus according to claim 1. 5. A latent image forming step of forming an electrostatic latent image on a laminated electrophotographic photosensitive member provided with a charge generation layer containing at least a phthalocyanine compound and a charge transport layer on a conductive support; A reversal development step of developing the electrostatic latent image to form a toner image by development, a first transfer step of transferring the toner image to an intermediate transfer member, and transferring the toner image on the intermediate transfer member to a transfer material A charge transfer layer in the layered electrophotographic photoreceptor, wherein the charge transport layer is represented by the following general formula (A) and a triphenylamine compound represented by the following general formula (B): N, N, N ', N'
-An image forming method comprising a charge transport material selected from tetraphenylbenzidine compounds. General formula (A) (However, in the general formula (A), R ₁ , R ₂ and R ₃ each represent a hydrogen atom, a halogen atom, an alkoxy group, a substituted or unsubstituted saturated or unsaturated aliphatic hydrocarbon group,
A substituted or unsubstituted aryl group or an atomic group necessary for forming a condensed polycyclic group by combining with a benzene ring.
k, m and n each represent an integer of 0-5. ) General formula (B) (However, in the general formula (B), R ₄ , R ₅ , R ₆ , R ₇ ,
R ₈ and R ₉ each represent a halogen atom, a hydroxyl group, an alkoxy group or an alkyl group. e, f, g and h are
Each represents an integer of 0 to 5. p and q are each 0
Represents an integer of from 4 to 4. )