JP2011064963A - Electrophotographic image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic image forming apparatus suppressing increase in a residual potential on a photoreceptor even when images are repeatedly formed. <P>SOLUTION: An image forming apparatus having a system requiring no destaticizing process is provided, including a photoreceptor having a photosensitive layer containing a tristyryl triphenylamine compound having a predetermined structure or a compound expressed by structural formula (2), a charging device, an exposing device, a developing device and a transfer device. In structural formula (2), R<SB>7</SB>to R<SB>12</SB>each represents a hydrogen atom, halogen atom, alkyl, alkoxy, aryl, or a hydrocarbon cyclic structure having two of R<SB>7</SB>to R<SB>12</SB>being bonded; g to i and k to l each represent an integer of 1 or more and 5 or less; and j represents an integer of 1 or more and 4 or less. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to an electrophotographic image forming apparatus.

  2. Description of the Related Art Conventionally, an image forming apparatus using a photoconductor includes a charging unit for charging the surface of the photoconductor, and an exposure unit for irradiating the charged surface with light to form an electrostatic latent image. An image forming process is employed in which a developing unit for developing the electrostatic latent image to form a toner image and a transfer unit for transferring the toner image to a recording medium are sequentially arranged.

  In this image forming apparatus, in order to erase a residual potential remaining in a photoconductor after a toner image is transferred to a recording medium, for example, a system provided with a neutralizing unit that neutralizes by irradiating light, and the neutralizing unit And a system that does not have

For example, a phthalocyanine compound, a hole transport agent, and an electron transport agent as a charge generating agent are contained in a binder resin on a conductive substrate, and the content of the phthalocinine compound is 0 with respect to the mass of the binder resin. Absolute sensitivity of positive and negative polarities measured at an exposure wavelength of 780 nm and an exposure energy of 1.0 μm / cm ² with a film thickness of 10 μm or more and 35 μm or less. A system using a single-layer type photoreceptor whose value difference is 500 V or less and having no static elimination means is disclosed (for example, see Patent Document 1).

  Also disclosed is a system that does not have a charge eliminating means and includes a photosensitive layer using an amine compound having a specific structure as a hole transporting agent (see, for example, Patent Document 2).

Japanese Patent Laid-Open No. 2001-312075 JP 2008-281723 A

  An object of the present invention is to provide a photoreceptor having a structure having a structure represented by Structural Formula (1) or Structural Formula (2) even when an image is repeatedly formed, compared with a case where a photosensitive body containing a compound containing a compound in a photosensitive layer is not provided. The purpose is to suppress an increase in the residual potential.

The above problem is solved by the following means.
The invention according to claim 1
A photosensitive layer containing at least one selected from compounds having the structure represented by the following structural formula (1) or the following structural formula (2) on a cylindrical substrate, and rotating about an axis; ,
In order toward the rotation direction of the photoconductor,
A charging device for charging the surface of the photoreceptor;
An exposure device that exposes the charged photoreceptor to form an electrostatic latent image;
A developing device for developing the electrostatic latent image with charged toner to form a toner image;
A transfer device that applies a bias having a polarity opposite to that of the toner to the photoconductor and the toner image, and transfers the toner image to a recording medium;
Further, it is downstream in the rotation direction of the photoconductor from the position where the transfer device faces the photoconductor, and in the rotation direction of the photoconductor than the position where the charging device faces the photoconductor. The electrophotographic image forming apparatus does not have a neutralizing device for neutralizing charges on the photoconductor in an upstream region.

[In the structural formula (1), R _{1 to} R ₆ each independently represent a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, or a substituted or unsubstituted carbon atom having 1 to 20 carbon atoms. A hydrocarbon ring structure in which an alkoxy group, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, or two substituents of R _{1 to} R ₆ are connected to each other, n and m are each independently An integer of 0 or more and a to f each independently represent an integer of 1 or more and 5 or less. ]

[In Structural Formula (2), R _{7 to} R ₁₂ are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, or a substituted or unsubstituted carbon atom having 1 to 20 carbon atoms. A hydrocarbon ring structure in which an alkoxy group, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, or two substituents of R _{7 to} R ₁₂ are connected to each other, g to i and k to l are , Each independently represents an integer of 1 to 5, and j represents an integer of 1 to 4. ]

The invention according to claim 2
The electrophotographic image forming apparatus according to claim 1, wherein the photosensitive layer includes a charge generation layer containing a hydroxygallium phthalocyanine pigment.

  According to the first aspect of the present invention, an image is formed repeatedly as compared with the case where the photosensitive layer containing the compound having the structure represented by the structural formula (1) or (2) is not provided. However, the increase in the residual potential in the photoreceptor is suppressed.

  According to the second aspect of the present invention, compared to the case where the photosensitive layer does not include the charge generation layer containing the hydroxygallium phthalocyanine pigment, the increase in the residual potential on the photosensitive member is suppressed even when the image is repeatedly formed.

1 is a schematic configuration diagram illustrating a configuration of an electrophotographic image forming apparatus according to an embodiment. FIG. 2 is a schematic configuration diagram illustrating a configuration of a photoreceptor in the present embodiment.

  Hereinafter, preferred embodiments of the present invention will be described in detail.

<Electrophotographic image forming apparatus>
The electrophotographic image forming apparatus according to the present embodiment (hereinafter sometimes simply referred to as “image forming apparatus”) has a structure represented by the following structural formula (1) or the following structural formula (2) on a cylindrical substrate. A photosensitive layer containing at least one selected from the compounds having the following: a photosensitive member that rotates about an axis; and a charging device that charges the surface of the photosensitive member in order toward the rotational direction of the photosensitive member; An exposure device that exposes the charged photoconductor to form an electrostatic latent image, a developing device that develops the electrostatic latent image with charged toner to form a toner image, the photoconductor and the toner A transfer device that applies a bias having a polarity opposite to that of the toner to the image and transfers the toner image to a recording medium. Further, it is further downstream in the rotation direction of the photoconductor than the position where the transfer device faces the photoconductor, and in the rotation direction of the photoconductor than the position where the charging device faces the photoconductor. In the upstream region, there is no neutralization device for neutralizing the charges on the photosensitive member (this configuration is hereinafter referred to as “static elimination-less system”).

[In the structural formula (1), R _{1 to} R ₆ each independently represent a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, or a substituted or unsubstituted carbon atom having 1 to 20 carbon atoms. A hydrocarbon ring structure in which an alkoxy group, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, or two substituents of R _{1 to} R ₆ are connected to each other, n and m are each independently An integer of 0 or more and a to f each independently represent an integer of 1 or more and 5 or less. ]

[In Structural Formula (2), R _{7 to} R ₁₂ are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, or a substituted or unsubstituted carbon atom having 1 to 20 carbon atoms. A hydrocarbon ring structure in which an alkoxy group, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, or two substituents of R _{7 to} R ₁₂ are connected to each other, g to i and k to l are , Each independently represents an integer of 1 to 5, and j represents an integer of 1 to 4. ]

  The image forming apparatus of the static elimination-less system performs static elimination on the photoconductor after the transfer process in which the toner image is transferred to the recording medium by the transfer apparatus and before the charging process in which the surface is charged by the charging apparatus. It does not have a known static elimination device (for example, an erase lamp) that performs intended exposure or the like.

  In the image forming apparatus of this static elimination-less system, since there is only a process having a static elimination action by a reverse polarity bias applied to the photosensitive member from the transfer device in the transfer process, the surface potential cannot be completely eliminated, and the photosensitive member is slightly removed. In some cases, the process proceeds to the next charging step with a residual potential remaining. For this reason, when the image forming apparatus of the static elimination-less system is repeatedly used, the residual potential is increased inside the photosensitive member.

  On the other hand, if the image forming apparatus according to this embodiment contains a compound having the structure represented by the structural formula (1) or the structural formula (2) in the photosensitive layer of the photoreceptor, the static elimination-less system is The surface potential is efficiently neutralized even if the process with a neutralizing action is only the application of a reverse polarity bias in the transfer process, so that the residual charge on the photoreceptor is prevented and the increase in the residual potential is suppressed, As a result, density abnormalities and fogging in the formed image are suppressed.

In the present embodiment, it is more desirable that the photosensitive layer includes a charge generation layer containing a hydroxygallium phthalocyanine pigment.
When a charge generation layer containing a hydroxygallium phthalocyanine pigment is provided, when the photosensitive layer is irradiated with light, the hydroxygallium phthalocyanine pigment contained in the photosensitive layer absorbs photons and generates carriers. At this time, since the phthalocyanine compound has high quantum efficiency, the phthalocyanine compound efficiently absorbs the absorbed photons to generate carriers, and has a structure represented by the structural formula (1) or the structural formula (2). The exchange of charges at the interface with the charge transport layer containing the charge transport material becomes smooth, and the generation of residual potential is further suppressed.

  Next, the configuration of the image forming apparatus according to the present embodiment will be described in detail with reference to the drawings.

FIG. 1 is a schematic configuration diagram showing an image forming apparatus according to the present embodiment.
The image forming apparatus shown in FIG. 1 forms an electrostatic latent image while rotating, and further charges a photosensitive drum 31 as an image carrier on which a toner image is formed, and the surface of the photosensitive drum 31 with a predetermined potential. A charger 32 composed of a contact charging type charging roller, a laser exposure device 26 for exposing the charged photosensitive drum 31 to form an electrostatic latent image, and an electrostatic formed on the photosensitive drum 31. The latent image is developed with the charged toner to form a toner image, the developing unit 33, the photosensitive drum 31, and the toner image formed on the photosensitive drum 31 by applying a bias having a polarity opposite to that of the toner. The transferred toner image is transferred to the recording medium P by the transfer unit, and the transfer roller 40 for discharging the charged potential of the photosensitive drum 31, and the surface of the photosensitive drum 31 after the toner image is transferred. With fixing device for fixing on the sheet P (not shown) of the cleaning blade 36, and the transferred toner image as a cleaning device for cleaning residual toner or the like, an image forming apparatus of neutralization less system.
Hereinafter, each component will be described.

-Photoconductor-
As described above, the photoreceptor used in this embodiment contains at least one selected from compounds having the structure represented by the structural formula (1) or the structural formula (2) on a cylindrical substrate. It is an essential requirement to provide a photosensitive layer.
The photosensitive layer may be a function-separated type having a layer structure in which a charge generation layer 52 and a charge transport layer 53 are laminated on a substrate 54 as shown in FIG. Further, the surface of the photosensitive layer (surface opposite to the base 54) may have a surface layer 55, for example, a surface layer containing a resin having a crosslinked structure. Further, an intermediate layer 51 may be provided between the photosensitive layer and the substrate 51, or an intermediate layer may be provided between the photosensitive layer and the surface layer 55.

  In the following description, the photoconductor used in this embodiment will be described in more detail on the assumption that the photoconductor is a function-separated type organic photoconductor. However, the layer structure of the photoconductor used in this embodiment is as follows. It is not limited to the following description.

・ Substrate As the cylindrical substrate, a metal drum such as aluminum, copper, iron, stainless steel, zinc, nickel, etc .; on a substrate such as sheet, paper, plastic, glass, aluminum, copper, gold, silver, platinum, palladium, Deposited metal such as titanium, nickel-chromium, stainless steel, copper-indium; Deposited conductive metal compound such as indium oxide and tin oxide on the substrate; Laminated metal foil on the substrate Carbon black, indium oxide, tin oxide-antimony oxide powder, metal powder, copper iodide and the like are dispersed in a binder resin and applied to the substrate to conduct a conductive treatment.

When a metal pipe base is used as the base, the surface of the metal pipe base may be a raw pipe, but the surface of the base may be previously roughened by surface treatment. Examples of the surface treatment method include mirror cutting, etching, anodizing, rough cutting, centerless grinding, sand blasting, wet honing and the like.
Moreover, you may use what performed the anodizing process on the surface of the aluminum base | substrate.

-Charge generation layer A charge generation layer is formed by vapor-depositing a charge generation material by a vacuum evaporation method, or by applying a solution containing an organic solvent and a binder resin.

  Examples of charge generation materials include amorphous selenium, crystalline selenium, selenium-tellurium alloy, selenium-arsenic alloy, other selenium compounds; selenium alloys, zinc oxide, titanium oxide, and other inorganic photoconductors; Sensitized, various phthalocyanine compounds such as metal-free phthalocyanine, titanyl phthalocyanine, copper phthalocyanine, tin phthalocyanine, and gallium phthalocyanine; Various organic pigments such as salts; or dyes are used.

  In addition, the above organic pigments generally have several types of crystals. In particular, phthalocyanine compounds have various crystal types including α type and β type. Any of these crystal forms can be used as long as it is a pigment obtained.

  Of the charge generation materials described above, phthalocyanine compounds are desirable. More desirable are chlorogallium phthalocyanine and hydroxygallium phthalocyanine, and particularly desirable is hydroxygallium phthalocyanine.

Examples of the binder resin used for the charge generation layer include the following. Polycarbonate resin such as bisphenol A type or bisphenol Z type and copolymer thereof, polyarylate resin, polyester resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polystyrene resin, polyvinyl acetate resin, styrene-butadiene copolymer resin, Examples thereof include vinylidene chloride-acrylonitrile copolymer resin, vinyl chloride-vinyl acetate-maleic anhydride resin, silicone resin, silicon-alkyd resin, phenol-formaldehyde resin, styrene-alkyd resin, poly-N-vinylcarbazole and the like.
These binder resins may be used alone or in combination of two or more.

The mixing ratio of the charge generation material and the binder resin (charge generation material: binder resin) is desirably in the range of 10: 1 to 1:10 by mass ratio.
In general, the thickness of the charge generation layer is desirably in the range of 0.01 μm to 5 μm, and more desirably in the range of 0.05 μm to 2.0 μm.

The charge generation layer may contain at least one electron accepting substance. Examples of the electron accepting material used in the charge generation layer include succinic anhydride, maleic anhydride, dibromomaleic anhydride, phthalic anhydride, tetrabromophthalic anhydride, tetracyanoethylene, tetracyanoquinodimethane, o-dinitrobenzene. M-dinitrobenzene, chloranil, dinitroanthraquinone, trinitrofluorenone, peak phosphoric acid, o-nitrobenzoic acid, p-nitrobenzoic acid, phthalic acid and the like. Of these, fluorenone-based, quinone-based, and benzene derivatives having electron-withdrawing substituents such as Cl, CN, NO ₂ are particularly desirable.

  As a method for dispersing the charge generating material in the resin, methods such as a roll mill, a ball mill, a vibrating ball mill, an attritor, a dyno mill, a sand mill, and a colloid mill are used.

  As a solvent of the coating solution for forming the charge generation layer, known organic solvents such as aromatic hydrocarbon solvents such as toluene and chlorobenzene, methanol, ethanol, n-propanol, iso-propanol, n-butanol and the like are used. Aliphatic alcohol solvents, ketone solvents such as acetone, cyclohexanone and 2-butanone, halogenated aliphatic hydrocarbon solvents such as methylene chloride, chloroform and ethylene chloride, cyclic or straight chain such as tetrahydrofuran, dioxane, ethylene glycol and diethyl ether Examples include chain ether solvents, ester solvents such as methyl acetate, ethyl acetate, and n-butyl acetate.

-Charge transport layer The charge transport layer in this embodiment must contain at least one selected from compounds having the structure represented by the following structural formula (1) or the following structural formula (2) as a charge transport material. As a requirement.

[In the structural formula (1), R _{1 to} R ₆ each independently represent a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, or a substituted or unsubstituted carbon atom having 1 to 20 carbon atoms. A hydrocarbon ring structure in which an alkoxy group, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, or two substituents of R _{1 to} R ₆ are connected to each other, n and m are each independently An integer of 0 or more and a to f each independently represent an integer of 1 or more and 5 or less. ]

[In Structural Formula (2), R _{7 to} R ₁₂ are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, or a substituted or unsubstituted carbon atom having 1 to 20 carbon atoms. A hydrocarbon ring structure in which an alkoxy group, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, or two substituents of R _{7 to} R ₁₂ are connected to each other, g to i and k to l are , Each independently represents an integer of 1 to 5, and j represents an integer of 1 to 4. ]

In the structural formula (1), examples of the halogen atom represented by R _{1 to} R ₆ include fluorine, chlorine, bromine, iodine, etc. Among these, fluorine and chlorine are preferable.

In the structural formula (1), examples of the alkyl group represented by R _{1 to} R ₆ include linear groups such as a methyl group, an ethyl group, a propyl group, a butyl group, an octyl group, and an octadecyl group, an isopropyl group, Examples thereof include branched chains such as t-butyl group, and among these, those having a relatively low molecular weight such as methyl group, ethyl group, and isopropyl group are desirable.

In the structural formula (1), examples of the alkoxy group represented by R _{1 to} R ₆ include a methoxy group and an ethoxy group, and among these, a methoxy group is desirable.

In the structural formula (1), examples of the aryl group represented by R _{1 to} R ₆ include a phenyl group, a naphthyl group, a phenanthryl group, and a biphenylyl group. Among these, a phenyl group and a naphthyl group are preferable.

  Examples of the substituent that substitutes for the alkyl group, alkoxy group, and aryl group include the halogen atom, alkoxy group, alkyl group, and aryl group.

In the structural formula (1), in the hydrocarbon ring structure in which two substituents together are linked of R ₁ to R _6, a group linking two substituents each other of R ₁ to R ₆ are, A single bond, a 2,2′-methylene group, a 2,2′-ethylene group, a 2,2′-vinylene group and the like can be mentioned. Among these, a single bond and a 2,2′-methylene group are desirable.

In the structural formula (1), R _{1 to} R ₆ are preferably a hydrogen atom or a methyl group among the above.

In the structural formula (1), n and m are preferably 0 or more and 2 or less.
In the structural formula (1), a to f are preferably 0 or more and 2 or less.

In the structural formula (2), examples of the halogen atom represented by R _{7 to} R ₁₂ include fluorine, chlorine, bromine, iodine, etc. Among these, fluorine and chlorine are preferable.

In the structural formula (2), the alkyl group represented by R _{7 to} R ₁₂ is a straight chain such as a methyl group, ethyl group, propyl group, butyl group, octyl group, octadecyl group, isopropyl group, t -A branched chain such as a butyl group is exemplified, and among these, those having a relatively low molecular weight such as a methyl group, an ethyl group, and an isopropyl group are desirable.

In the structural formula (2), examples of the alkoxy group represented by R _{7 to} R ₁₂ include a methoxy group and an ethoxy group, and among these, a methoxy group is desirable.

In the structural formula (2), examples of the aryl group represented by R _{7 to} R ₁₂ include a phenyl group, a naphthyl group, a phenanthryl group, and a biphenylyl group. Among these, a phenyl group and a naphthyl group are preferable.

  Examples of the substituent that substitutes for the alkyl group, alkoxy group, and aryl group include the halogen atom, alkoxy group, alkyl group, and aryl group.

In the above structural formula (2), in the hydrocarbon ring structure in which two substituents together out of R ₇ to R ₁₂ are linked, as the group linking the two substituents together out of R ₇ to R ₁₂ are, A single bond, a 2,2′-methylene group, a 2,2′-ethylene group, a 2,2′-vinylene group and the like can be mentioned. Among these, a single bond and a 2,2′-methylene group are desirable.

In the structural formula (2), R _{7 to} R ₁₂ are preferably a hydrogen atom, a methyl group, or a methoxy group among the above.

  In the structural formula (2), g to l are preferably 0 or more and 2 or less.

  Specific examples of the compounds having the structures represented by the structural formulas (1) and (2) are shown below.

  The charge transport layer may be formed using a charge transport material and a binder resin.

In addition to the compound having the structure represented by the structural formula (1) or the structural formula (2), other charge transport materials may be contained. Other charge transport materials include quinone compounds such as p-benzoquinone, chloranil, bromanyl and anthraquinone, tetracyanoquinodimethane compounds, fluorenone compounds such as 2,4,7-trinitrofluorenone, xanthone compounds, Electron transport compounds such as benzophenone compounds, cyanovinyl compounds, ethylene compounds, triarylamine compounds, benzidine compounds, arylalkane compounds, aryl-substituted ethylene compounds, stilbene compounds, anthracene compounds, hydrazone compounds And hole transporting compounds such as
These other charge transport materials may be used alone or in combination of two or more, and are not limited thereto.

Further, the binder resin used for the charge transport layer includes polycarbonate resin, polyester resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinylidene chloride resin, polystyrene resin, polyvinyl acetate resin, styrene-butadiene copolymer, vinylidene chloride. -Acrylonitrile copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicone resin, silicone-alkyd resin, phenol-formaldehyde resin, styrene-alkyd resin, poly-N -Vinylcarbazole, polysilane, polymer charge transport materials such as polyester polymer charge transport materials disclosed in JP-A-8-176293 and JP-A-8-208820 are used. More desirably, it is a polycarbonate-based resin, and a copolymer including a plurality of polycarbonate structures may be used.
These binder resins are used alone or in combination of two or more.

The blending ratio (mass ratio) between the charge transport material and the binder resin is preferably 10: 1 to 1: 5.
The proportion of the compound having the structure represented by the structural formula (1) or the structural formula (2) in the total charge transporting material is preferably 10% by mass or more and 100% by mass or less.

In general, the thickness of the charge transport layer is preferably from 5 μm to 50 μm, and more preferably from 9 μm to 28 μm.
As a coating method, a usual method such as a blade coating method, a Mayer bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method, or a curtain coating method is used.

  Furthermore, as a solvent used when providing a charge transport layer, aromatic hydrocarbons such as benzene, toluene, xylene and chlorobenzene, ketones such as acetone and 2-butanone, and halogenation such as methylene chloride, chloroform and ethylene chloride Usual organic solvents such as aliphatic hydrocarbons, cyclic or linear ethers such as tetrahydrofuran and ethyl ether are used alone or in admixture of two or more.

Moreover, you may add additives, such as antioxidant, a light stabilizer, and a heat stabilizer, in a photosensitive layer.
For example, examples of the antioxidant include hindered phenol, hindered amine, paraphenylenediamine, arylalkane, hydroquinone, spirochroman, spiroidanone and derivatives thereof, organic sulfur compounds, and organic phosphorus compounds. Examples of the light stabilizer include derivatives such as benzophenone, benzotriazole, dithiocarbamate, and tetramethylpiperidine.

Further, at least one kind of electron accepting substance may be contained. Examples of the electron accepting material that can be used in the charge transport layer in the present embodiment include succinic anhydride, maleic anhydride, dibromomaleic anhydride, phthalic anhydride, tetrabromophthalic anhydride, tetracyanoethylene, tetracyanoquinodimethane. O-dinitrobenzene, m-dinitrobenzene, chloranil, dinitroanthraquinone, trinitrofluorenone, picric acid, o-nitrobenzoic acid, p-nitrobenzoic acid, phthalic acid and the like. Of these, benzene derivatives having an electron-withdrawing substituent such as fluorenone, quinone, Cl, CN, and NO ₂ are particularly desirable.

  Furthermore, various particles may be added to the charge transport layer. Examples of the particles include fluorine-based particles such as ethylene tetrafluoride, ethylene trifluoride, propylene hexafluoride, vinyl fluoride, and vinylidene fluoride, and “Abstracts of the 8th Polymer Materials Forum Lectures pp89-90”. And particles made of a resin obtained by copolymerizing the fluororesin and a monomer having a hydroxyl group. These particles may be used alone or in combination.

  Oil such as silicone oil may be added. Examples of the silicone oil include silicone oils such as dimethylpolysiloxane, diphenylpolysiloxane, and phenylmethylsiloxane, amino-modified polysiloxane, epoxy-modified polysiloxane, carboxyl-modified polysiloxane, carbinol-modified polysiloxane, fluorine-modified polysiloxane, methacryl Examples thereof include reactive silicone oils such as modified polysiloxane, mercapto-modified polysiloxane, and phenol-modified polysiloxane.

-Charging device-
An example of the charging device used in the present embodiment is a charger using a contact charging method. In the contact charging method, various known forms such as a roller, a brush, and a film are used. A roller-shaped charging member is particularly desirable. The roller-shaped charging member is preferably brought into contact with the photoreceptor at a pressure of 250 mgf to 600 mgf.

The roller-shaped charging member is composed of a material adjusted to an electrical resistance (10 ³ Ω to 10 ⁸ Ω) effective as a charging member, and may be composed of a single layer or a plurality of layers. .

  Materials constituting the charging member include urethane rubber, silicon rubber, fluorine rubber, chloroprene rubber, butadiene rubber, EPDM (ethylene-propylene-diene copolymer rubber), epichlorohydrin rubber and other synthetic rubbers, polyolefin, polystyrene, vinyl chloride, etc. A material obtained by blending an optional conductivity imparting agent such as conductive carbon, metal oxide, or ionic conductive agent is used.

  In addition, nylon, polyester, polystyrene, polyurethane, silicone, and other resins are made into paints, and conductive imparting agents such as conductive carbon, metal oxides, and ionic conductive agents are blended there, and the resulting paints are dipped, sprayed, rolled You may laminate | stack and use by methods, such as application | coating.

-Exposure device-
As the exposure apparatus used in this embodiment, a known exposure apparatus is used. For example, as an exposure light source, a laser beam emitted from a single light emitting laser element that forms a minute spot diameter or a surface emitting laser element in which a plurality of semiconductor lasers (light emitting points) are two-dimensionally arranged in a plane is a polygon mirror And a plurality of LED (Light Emitting Diode) elements arranged in a straight line or a staggered pattern. The light source irradiates the photosensitive drum with light corresponding to the writing image data from the image processing apparatus, thereby writing the image. The amount of light at the time of writing is desirably 0.5 mJ / m ² or more and 5.0 mJ / m ² or less on the surface of the photoreceptor.

-Developer-
The developing device used in this embodiment is not particularly limited as long as it is a publicly known developing device, for example, a two-component developing type developing device that develops a developing brush made of carrier and toner in contact with a photosensitive member, For example, a contact type one-component development type developing device that adheres toner onto a conductive rubber conveyance roll (development roll) and develops the toner on a photoreceptor is used.

  In the case of the two-component development method, the rotation direction of the developing roll may be the same as or opposite to the rotation direction of the photoconductor. The electric field applied to the developing roll may be a direct current or an alternating current superimposed on the direct current.

  The magnetic brush formed on the surface of the developing roll is regulated by the layer regulating member so that the magnetic brush density facing the photoconductor does not change, so that the magnetic brush density can be adjusted within an appropriate range. desirable.

  When the normal polarity of the toner is negative, the bias applied to the developing roll is preferably −50 V or lower and −600 V or higher, more preferably −100 V or lower and −350 V or higher.

-Toner-
The toner used in the exemplary embodiment is not particularly limited as long as it is a known toner. Further, the toner contains a binder resin and a colorant, and may contain a release agent as necessary. Furthermore, external additives other than those described above may be added.

  The toner may contain various components in order to control various characteristics. For example, when used as a magnetic toner, a magnetic powder (for example, ferrite or magnetite), a metal such as reduced iron, cobalt, nickel, or manganese, an alloy, or a compound containing these metals is contained. Further, a commonly used charge control agent such as a quaternary ammonium salt, a nigrosine compound or a triphenylmethane pigment may be selected and contained.

  Furthermore, a known external additive such as a lubricant and a transfer aid may be externally added to the toner, if necessary, in addition to the abrasive composed of inorganic particles.

  The method for producing the toner used in the present embodiment is not particularly limited. For example, a normal pulverization method, a wet melt spheronization method prepared in a dispersion medium, suspension polymerization, dispersion polymerization, A toner production method using a known polymerization method such as an emulsion polymerization aggregation method is used.

-Career-
When the developer used in this embodiment is a two-component developer composed of a toner and a carrier, the carrier that can be used is not particularly limited, and a known carrier is used. For example, a carrier (non-coated carrier) consisting only of a core material such as a magnetic metal such as iron oxide, nickel or cobalt, or a magnetic oxide such as ferrite or magnetite, or a resin-coated carrier provided with a resin layer on the surface of these core materials Is used.

  In the two-component developer using the carrier described above, the mixing ratio (mass ratio) of the toner and the carrier is desirably in the range of toner: carrier = 1: 100 to 30: 100, and 3: 100 to A range of 20: 100 is more desirable.

-Transfer device-
The transfer device according to the present embodiment applies a bias having a polarity opposite to that of the toner to the photoconductor and the toner image to transfer the toner image formed on the photoconductor to the recording medium at the transfer unit and is charged. This is a device for eliminating the potential on the photoreceptor.

As the transfer device used in this embodiment, a transfer device using a known method is used. For example, a non-contact type such as corotron or scorotron, and a contact type using a transfer roll can be used.
In addition, when transferring a toner image from a photosensitive member, a direct transfer method using a transfer belt method in which a recording medium is electrostatically attracted and conveyed to transfer a toner image on the photosensitive member can be cited. The transfer method to the recording medium is not limited, and an intermediate transfer method using an intermediate transfer member such as an intermediate transfer belt or an intermediate transfer drum may be used.

-Cleaning device-
A known cleaning method is used as the cleaning means used in the present embodiment. For example, when a cleaning blade is used, the cleaning blade is made of a member having elasticity at the portion in contact with the surface of the photoreceptor, and the 100% modulus of the member having elasticity is preferably 6.5 MPa or more, and 7.0 MPa or more. It is more desirable that the pressure is 9.0 MPa or more. On the other hand, the 100% modulus of the elastic member is preferably 19.6 MPa or less, and more preferably 15.0 MPa or less.

  The elastic member preferably has an elongation at break of 250% or more, more preferably 300% or more, and further preferably 350% or more.

  As a material constituting the cleaning blade, a known rubber body is used, and other materials may be added. The rubber body is not particularly limited, and rubber urethane rubber, silicone rubber, acrylic rubber, acrylonitrile rubber, butadiene rubber, styrene rubber, or a composite material thereof is used. Further, a plate shape is preferably used as the shape of the cleaning blade, and it is formed using centrifugal molding, extrusion molding, mold molding or the like.

-Operation of image forming apparatus-
Next, the operation of the image forming apparatus according to this embodiment will be described.
At the time of image formation, an image forming operation is executed under the control of the control unit. Specifically, image data input from a computer, an image reading device, or the like is supplied to the laser exposure device 26 after being subjected to image processing by an image processing unit. Then, the laser exposure device 26 scans and exposes the photosensitive drum 31 whose surface is charged by the charger 32. Thereby, an electrostatic latent image is formed on the photosensitive drum 31. The formed electrostatic latent image is developed by the developing device 33, and a toner image is formed on the photosensitive drum 31. Here, the toner used in the developing device 33 of the present embodiment has a negative polarity.
When the toner image is conveyed to the transfer unit, the paper P is supplied to the transfer unit. In the transfer portion, the toner images are collectively electrostatically transferred onto the paper P by the action of the transfer electric field formed between the transfer roll 40 and the photosensitive drum 31. In addition, the potential on the photosensitive drum 31 charged by the action of the transfer electric field is removed.
Thereafter, the paper P on which the toner image is transferred is conveyed to a fixing device (not shown), and the unfixed toner image on the paper P is subjected to a fixing process by heat and / or pressure by the fixing device (not shown). It is fixed on the paper P. Then, the paper P on which the fixed image is formed is conveyed to a paper discharge unit provided in a discharge unit of the image forming apparatus.
On the surface of the photoconductive drum 31 after the transfer process in the transfer unit is performed, the toner remaining on the surface of the photoconductive drum 31, the toner retransferred from the transfer roll 40, and the like are removed by the cleaning blade 36. In the image forming apparatus according to the present embodiment, this image forming cycle is repeated.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example at all. In the following description, “part” means “part by mass” unless otherwise specified.

[Example 1]
-Production of photoconductor-
-Undercoat layer 100 parts of zinc oxide (average particle size: 70 nm, manufactured by Teika, specific surface area value: 15 m ² / g) is stirred and mixed with 500 parts of methanol, and KBM603 (manufactured by Shin-Etsu Chemical Co., Ltd.) is used as a silane coupling agent. 1.5 parts were added and stirred for 2 hours. Thereafter, methanol was distilled off under reduced pressure, and baking was performed at 120 ° C. for 3 hours to obtain silane coupling agent surface-treated zinc oxide particles.

  60 parts of the zinc oxide particles subjected to the surface treatment, 0.6 part of alizarin, 13.5 parts of blocked isocyanate (Sumidule 3475, manufactured by Sumitomo Bayern Urethane Co., Ltd.) as a curing agent, butyral resin (ESREC BM-1) (Manufactured by Sekisui Chemical Co., Ltd.) 15 parts, 38 parts of a solution obtained by dissolving 85 parts of methyl ethyl ketone and 25 parts of methyl ethyl ketone are mixed, and dispersion is performed using a glass bead having a diameter of 1 mm for 4 hours in a sand mill. Got. To the obtained dispersion, 0.005 part of dioctyltin dilaurate and 4.0 parts of silicone resin particles (Tospearl 130, manufactured by GE Toshiba Silicone) were added as a catalyst to obtain a coating liquid for undercoat layer. . This coating solution was applied onto an aluminum substrate having a diameter of 30 mm by a dip coating method and dried at 170 ° C. for 30 minutes to obtain an undercoat layer having a thickness of 20 μm.

Charge generation layer Next, as a charge generation material, it is strong at least 7.4 °, 16.6 °, 25.5 ° and 28.3 ° of the Bragg angle (2θ ± 0.2 °) with respect to CuKα characteristic X-rays A mixture of 15 parts of a chlorogallium phthalocyanine crystal having a diffraction peak, 10 parts of a vinyl chloride-vinyl acetate copolymer resin (VMCH, manufactured by Nippon Union Carbide) and 300 parts of n-butyl alcohol, and glass beads having a diameter of 1 mm. The resultant was dispersed in a sand mill for 4 hours to obtain a coating solution for a charge generation layer. This charge generation layer coating solution was dip coated on the undercoat layer and dried to obtain a charge generation layer having a thickness of 0.2 μm.

Charge transport layer Next, 8 parts (average particle size: 0.2 μm) of tetrafluoroethylene resin particles and 0.02 part of fluorinated alkyl group-containing methacrylic copolymer (weight average molecular weight: 80000) were added to 3 parts of tetrahydrofuran and 2 toluene. The mixture was stirred and mixed for 48 hours to obtain a tetrafluoroethylene resin particle suspension A. Next, 4 parts of tris [4- (4,4-diphenyl-1,3-butadienyl) phenyl] amine having the structure shown in the above-mentioned “specific example (1)” as a charge transport material and bisphenol Z as a binder resin 6 parts polycarbonate resin (viscosity average molecular weight: 40,000), 0.1 part 2,6-di-tert-butyl-4-methylphenol as an antioxidant, 24 parts tetrahydrofuran and 11 parts toluene It melt | dissolved and the mixed solution B was obtained. After adding the A liquid to the B liquid and stirring and mixing, the pressure is increased to 500 kgf / cm ² using a high-pressure homogenizer (manufactured by Yoshida Kikai Kogyo Co., Ltd.) equipped with a through-type chamber having a fine flow path. 10 ppm of fluorine-modified silicone oil (trade name: FL-100, manufactured by Shin-Etsu Silicone) was added to the solution obtained by repeating the treatment four times, and stirred to obtain a coating solution for a charge transport layer.

  This coating solution was applied onto the charge generation layer and dried at 130 ° C. for 25 minutes to form a charge transport layer having a thickness of 20 μm, thereby obtaining the intended electrophotographic photosensitive member.

[Example 2]
In Example 1, the target electrophotographic photosensitive member was prepared by the method described in Example 1 except that the charge transporting material was changed to 4 parts of the enamine derivative having the structure shown in the above-mentioned “specific example (2)”. Obtained.

Example 3
In Example 1, the charge generating material is resistant to at least 7.4 °, 16.6 °, 25.5 ° and 28.3 ° of the Bragg angle (2θ ± 0.2 °) with respect to the CuKα characteristic X-ray described above. The target electrophotographic photoreceptor was obtained by the method described in Example 1, except that the hydroxygallium phthalocyanine crystal having a diffraction peak was changed to 15 parts.

Example 4
In Example 1, the target electrophotographic photosensitive member was prepared by the method described in Example 1 except that the charge generation material was changed to 15 parts of a metal-free phthalocyanine crystal represented by the charge generation material (X) shown below. Got.

[Comparative Example 1]
In Example 1, the target electrophotographic photoreceptor was obtained by the method described in Example 1 except that the charge transport material was changed to 4 parts of the charge transport material (Y) shown below.

[Comparative Example 2]
In Comparative Example 1, the target electrophotographic photosensitive member was obtained by the method described in Example 1 except that the charge generating material was changed to 15 parts of phthalocyanine crystals represented by the charge generating material (X) shown below. It was.

  The photoconductors obtained in the examples and comparative examples are incorporated as photoconductor drums 31 of an image forming apparatus having a configuration shown in FIG. 1 (a modified machine obtained by removing a static eliminator from DocuPrint C2110 (manufactured by Fuji Xerox)). The following evaluation was performed.

≪Evaluation test≫
-Exposed area -Non-exposed area charged potential difference-
The charged potential difference (ΔVh) between the exposed portion and the non-exposed portion is the charge potential between the exposed portion and the non-exposed portion when the charging step is performed after the charging, exposing, and transferring steps are sequentially performed once in the image forming apparatus. It was measured using a surface potential meter Trek 334 (manufactured by Trek), and the difference in potential was determined.

-Residual potential stability-
Residual potential stability (ΔRp) was measured using a surface potentiometer Trek 334 (manufactured by Trek) for the residual potential of the photoreceptor after the charging, exposure, and transfer steps in the image forming apparatus. Subsequently, the residual potential is measured by the above method every time 2,000 images are formed, and the residual potential is continuously measured up to 10,000. The difference between the initial residual potential at this time and the residual potential after every 2000 images are formed. Was defined as residual potential stability (ΔRp).

In addition, the fogging of the obtained image was evaluated. The evaluation criteria for fogging are as follows.
○: No visible fogging ×: Visually obvious fogging

DESCRIPTION OF SYMBOLS 26 ... Laser exposure apparatus, 31 ... Photoconductor drum, 32 ... Charger, 33 ... Developing device, 36 ... Cleaning blade, 40 ... Transfer roll, 51 ... Intermediate layer, 52 ... Charge generation layer, 53 ... Charge transport layer, 54 ... Base, 55 ... Surface layer, P ... Paper

Claims (2)

A photosensitive layer containing at least one selected from compounds having the structure represented by the following structural formula (1) or the following structural formula (2) on a cylindrical substrate, and rotating about an axis; ,
In order toward the rotation direction of the photoconductor,
A charging device for charging the surface of the photoreceptor;
An exposure device that exposes the charged photoreceptor to form an electrostatic latent image;
A developing device for developing the electrostatic latent image with charged toner to form a toner image;
A transfer device that applies a bias having a polarity opposite to that of the toner to the photoconductor and the toner image, and transfers the toner image to a recording medium;
Further, it is downstream in the rotation direction of the photoconductor from the position where the transfer device faces the photoconductor, and in the rotation direction of the photoconductor than the position where the charging device faces the photoconductor. An electrophotographic image forming apparatus that does not have a static eliminator for neutralizing charges on the photoconductor in an upstream area.

[In the structural formula (1), R _{1 to} R ₆ each independently represent a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, or a substituted or unsubstituted carbon atom having 1 to 20 carbon atoms. A hydrocarbon ring structure in which an alkoxy group, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, or two substituents of R _{1 to} R ₆ are connected to each other, n and m are each independently An integer of 0 or more and a to f each independently represent an integer of 1 or more and 5 or less. ]


[In Structural Formula (2), R _{7 to} R ₁₂ are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, or a substituted or unsubstituted carbon atom having 1 to 20 carbon atoms. A hydrocarbon ring structure in which an alkoxy group, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, or two substituents of R _{7 to} R ₁₂ are connected to each other, g to i and k to l are , Each independently represents an integer of 1 to 5, and j represents an integer of 1 to 4. ] The electrophotographic image forming apparatus according to claim 1, wherein the photosensitive layer includes a charge generation layer containing a hydroxygallium phthalocyanine pigment.