JP2013195834A - Image forming apparatus and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus capable suppressing a residual image caused by a history of the previous cycle.SOLUTION: An image forming apparatus 200 includes: an electrophotographic photoreceptor 7 having a conductive support member, an undercoat layer disposed on the conductive support member and containing a conductive metallic oxide and electron-receptive material, and a photosensitive layer disposed on the undercoat layer; charging-means 208 for charging the surface of the electrophotographic photoreceptor; exposure means 210 for forming an electrostatic latent image by exposing the charged surface of the electrophotographic photoreceptor; development means 211 for housing a developer containing toner and forming a toner image by developing the electrostatic latent image with the developer; transfer means 212 for transferring the toner image formed on the surface of the electrophotographic photoreceptor onto a recording medium 500. Further, the entire surface of the electrophotographic photoreceptor is exposed by the exposure means before charging the surface of the electrophotographic photoreceptor by the charging-means when restarting image-forming after it has been temporarily stopped.

Description

  The present invention relates to an image forming apparatus and an image forming method.

  Electrophotographic image formation has the advantages of high speed and high print quality, and is therefore widely used in fields such as copying machines and laser beam printers. In an image forming apparatus such as a copying machine or a laser beam printer, the electrostatic latent image formed on the electrophotographic photosensitive member is developed by a charging and exposure device using a corona charger or a conductive roller, and then transferred. The image is transferred to a recording medium such as recording paper in the process, and then fixed to the recording medium such as recording paper with heat and pressure in the fixing process to form an image.

  For example, Patent Document 1 discloses that in an image forming apparatus using an electrophotographic photosensitive member having at least an intermediate layer and a photosensitive layer on a conductive support, the intermediate layer contains a compound having an electron transporting ability, An image forming apparatus using the electrophotographic photosensitive member having an intermediate transfer member formed in contact with the photosensitive member is disclosed.

  In Patent Document 2, an electrophotographic photosensitive member, a pre-exposure unit that performs a charge removal process on the surface of the electrophotographic photosensitive member by exposure before a charging unit that charges the electrophotographic photosensitive member, and the electrophotographic photosensitive member are charged. Charging means; image exposing means for exposing the charged electrophotographic photosensitive member to form an electrostatic latent image; developing means for developing toner on the electrophotographic photosensitive member having the electrostatic latent image formed thereon; A transfer means for transferring a toner image on a photographic photosensitive member onto a transfer material, and the electrophotographic photosensitive member has at least a charge generation layer and a hole transport layer in this order on a conductive support; An electrophotographic apparatus that defines the relationship between the surface potential of the film and the film thickness of the hole transport layer is disclosed.

JP 2004-93808 A JP 2007-3899 A

  An object of the present invention is to provide an image forming apparatus in which an afterimage (hereinafter referred to as “ghost image” as appropriate) due to the history of the previous cycle is not easily generated even if the static eliminator is not provided.

The invention of claim 1 is a conductive support, an undercoat layer disposed on the conductive support and comprising a conductive metal oxide and an electron accepting substance, and a photosensitive layer disposed on the undercoat layer. An electrophotographic photosensitive member, a charging unit for charging the surface of the electrophotographic photosensitive member, an exposure unit for exposing the charged surface of the electrophotographic photosensitive member to form an electrostatic latent image, and development including toner Developing means for containing an agent and developing the electrostatic latent image with the developer to form a toner image; and transfer means for transferring the toner image formed on the surface of the electrophotographic photosensitive member to a recording medium; When the image formation is resumed after the image formation is temporarily stopped, the entire surface of the electrophotographic photosensitive member is exposed by the exposing means before the surface of the electrophotographic photosensitive member is charged by the charging means. Image forming apparatus to be exposed.
According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the volume resistivity of the undercoat layer of the electrophotographic photosensitive member is in the range of 10 ⁸ Ωcm to 10 ¹¹ Ωcm.
According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, the charging unit has a charging member to which only a DC voltage is applied and which is charged in contact with the surface of the electrophotographic photosensitive member.
According to a fourth aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects, the exposure unit performs the overall exposure on the surface of the electrophotographic photosensitive member at 3 mJ / m ² or more.
According to a fifth aspect of the present invention, there is provided a conductive support, an undercoat layer disposed on the conductive support and comprising a conductive metal oxide and an electron accepting substance, and a photosensitive layer disposed on the undercoat layer. A charging step for charging the surface of the electrophotographic photosensitive member, an electrostatic latent image forming step for exposing the charged surface of the electrophotographic photosensitive member to form an electrostatic latent image, and the electrostatic latent image as a toner A development process for developing a toner image by developing with a developer containing the toner, a transfer process for transferring the toner image formed on the surface of the electrophotographic photosensitive member to a recording medium, and image formation after temporarily stopping image formation And a pre-exposure step of exposing the entire surface of the electrophotographic photosensitive member by an exposure unit that forms the electrostatic latent image before the charging step.

According to the first aspect of the present invention, an electrophotographic photosensitive member having an undercoat layer containing a conductive metal oxide and an electron-accepting substance, and image formation once stopped when no static eliminator is provided. When resuming the formation, the ghost image is compared with the case where the exposure means does not combine the entire exposure of the surface of the electrophotographic photosensitive member before charging the surface of the electrophotographic photosensitive member by the charging means. An image forming apparatus that is difficult to come out is provided.
According to the second aspect of the present invention, there is provided an image forming apparatus in which a ghost image is hardly generated as compared with a case where the volume resistivity of the undercoat layer of the electrophotographic photosensitive member is outside the above range.
According to the third aspect of the present invention, there is provided an image forming apparatus in which a ghost image is not easily generated even when the charging means has a charging member to which only the DC voltage is applied and which contacts and charges the surface of the electrophotographic photosensitive member. The
According to the fourth aspect of the present invention, there is provided an image forming apparatus in which the exposure means is less likely to produce a ghost image compared to a case where the entire exposure of the surface of the electrophotographic photosensitive member is performed at less than 3 mJ / m ² .
According to the invention of claim 5, an electrophotographic photosensitive member having an undercoat layer containing a conductive metal oxide and an electron accepting substance when it does not include a charge eliminating step for removing the residual potential on the surface of the electrophotographic photosensitive member. And the entire surface of the electrophotographic photosensitive member is exposed by an exposure unit for forming an electrostatic latent image before the charging step when the image formation is resumed after the image formation is temporarily stopped. An image forming method in which a ghost image is less likely to be produced compared to the case where there is no image.

1 is a schematic diagram illustrating an example of an image forming apparatus according to an exemplary embodiment. 1 is a schematic cross-sectional view illustrating an example of an electrophotographic photosensitive member of the present embodiment.

  The static eliminator has a function of erasing the previous cycle history by irradiating the entire surface of the photoconductor before charging. However, from the viewpoint of reducing manufacturing costs, the static eliminator is not equipped with a static eliminator, and the history of the previous cycle is provided by some means. It is desirable to make it difficult to see. In an image forming apparatus that does not have a static eliminator, charging of the next cycle is performed with the image history of the previous cycle remaining, but it does not have a static eliminator and is particularly a contact charging type charging means that only applies a DC voltage. When is used, the low charging ability also overlaps, and an afterimage (ghost image) due to the history of the previous cycle is likely to occur.

  Therefore, the present inventors have conducted research and examination on a technique for suppressing the generation of a ghost image even in an image forming apparatus that does not have a static eliminator. As a result, an electron-accepting substance and a conductive metal are formed in the undercoat layer. When an electrophotographic photosensitive member containing oxide particles is used and an image formation is resumed, an electrostatic latent image is formed on the surface of the photosensitive member before charging the surface of the electrophotographic photosensitive member by the charging unit. It has been found that by exposing the entire surface of the photoreceptor with the exposure means, the generation of a ghost image due to the image history of the previous cycle is suppressed. The reason is presumed as follows.

  Since the undercoat layer of the electrophotographic photosensitive member contains metal oxide particles and an electron accepting substance, in the image formation of the previous cycle, not only in the area where the latent image is formed but also in the area where the latent image is not formed. However, it is considered that residual charges are easily accumulated, and the difference in residual potential between the area where the latent image is formed and the area where the latent image is not formed is reduced. In addition, since a ghost image is likely to occur in the first image when image formation is resumed, the entire cycle is exposed by the exposure means only before the surface of the electrophotographic photosensitive member is first charged when image formation is resumed. It is considered that the difference in residual potential between the latent image forming area and the latent image non-forming area becomes smaller, and the generation of a ghost image at the time of restarting image formation is suppressed.

  Hereinafter, the electrophotographic photosensitive member of this embodiment will be described in detail.

  The image forming apparatus according to the present embodiment is disposed on the conductive support, the conductive support, the subbing layer including a conductive metal oxide and an electron accepting substance, and the subbing layer. An electrophotographic photosensitive member having a photosensitive layer, a charging unit for charging the surface of the electrophotographic photosensitive member, an exposure unit for exposing the charged surface of the electrophotographic photosensitive member to form an electrostatic latent image, and a toner Developing means for developing the electrostatic latent image with the developer to form a toner image, and transfer for transferring the toner image formed on the surface of the electrophotographic photosensitive member to a recording medium And when the image formation is resumed after the image formation is temporarily stopped, before the surface of the electrophotographic photosensitive member is charged by the charging means, the exposure means Configured to expose the entire surface

FIG. 1 is a schematic diagram illustrating an example of an image forming apparatus according to the present embodiment. An image forming apparatus 200 shown in FIG. 1 is connected to a power source 209 and applied with only a DC voltage, and is charged by a charging device 208 (charging means) of a contact charging system that charges the electrophotographic photosensitive member 7 and the charging device 208. An exposure device 210 (exposure means) for exposing the electrophotographic photosensitive member 7 to form an electrostatic latent image and a developer containing toner are accommodated, and the electrostatic latent image formed by the exposure device 210 is developed with the developer. A developing device 211 (developing means) for forming a toner image, a transfer device 212 (transfer means) for transferring the toner image formed on the surface of the electrophotographic photosensitive member 7 to the transfer medium 500, and an electron after transfer. A cleaning device 213 (cleaning means) that removes toner remaining on the surface of the photoconductor 7 and a fixing device 2 that fixes the toner image transferred to the transfer medium 500 to the transfer medium 500. It includes 5 and (fixing means), a. Note that the image forming apparatus shown in FIG. 1 is not provided with a charge-removing device dedicated to charge removal for removing the residual potential.
Hereinafter, each unit constituting the image forming apparatus according to the present embodiment will be described in detail.

<Electrophotographic photoreceptor>
The electrophotographic photosensitive member used in the present embodiment is a conductive support, an undercoat layer disposed on the conductive support and containing a conductive metal oxide and an electron-accepting substance, and the undercoat layer. Having a photosensitive layer disposed thereon;

FIG. 2 schematically shows an example of the layer structure of the electrophotographic photosensitive member used in this embodiment. The electrophotographic photoreceptor 7 has a structure in which an undercoat layer 2, an intermediate layer 4, a photosensitive layer 3, and a protective layer 5 are sequentially laminated on a conductive support 1. The electrophotographic photoreceptor 7 shown in FIG. 2 is a function separation type photoreceptor, and the photosensitive layer 3 is composed of a charge generation layer 31 and a charge transport layer 32.
The protective layer 5 preferably includes a resin having a crosslinked structure, and the resin having a crosslinked structure preferably has charge transport properties.
In addition, the intermediate | middle layer 4 and the protective layer 5 are provided as needed. Further, it may be a function-integrated type photoreceptor having a photosensitive layer in which the charge generation layer 31 and the charge transport layer 32 are integrally formed.

  In the following description, the electrophotographic photosensitive member used in the present embodiment will be described in more detail on the assumption that it is a function-separated type organic photosensitive member 7 having the layer configuration shown in FIG. The layer structure of the electrophotographic photosensitive member used in is not limited to the following description.

(Conductive support)
Examples of the conductive support 1 include aluminum, copper, iron, stainless steel, zinc, nickel and other metal drums; aluminum, copper, gold, silver, platinum, palladium, titanium on a substrate such as a sheet, paper, plastic, and glass. , Nickel-chromium, stainless steel, copper-indium or the like deposited on metal; conductive metal compound such as indium oxide or tin oxide deposited on the substrate; metal foil laminated 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.
The shape of the conductive support 1 may be any of a drum shape, a sheet shape, and a plate shape.
In this embodiment, conductivity means a range of 10 ¹⁰ Ωcm or less in terms of volume resistivity, and insulation means a range of 10 ¹² Ωcm or more in terms of volume resistivity.

When a metal pipe is used as the conductive support 1, the surface of the metal pipe may be a raw pipe, but the surface of the pipe may be roughened by surface treatment in advance. Due to such roughening, when a coherent light source such as a laser beam is used as the exposure light source, grain-like density unevenness due to interference light that can be generated inside the electrophotographic photosensitive member is suppressed.
Examples of surface treatment (roughening) methods include mirror cutting, etching, anodizing, rough cutting, centerless grinding, sand blasting, and wet honing.
In particular, in terms of improving adhesion to the photosensitive layer and improving film formability, it is preferable to use, for example, an anodized surface of the aluminum support as the conductive support.

(Undercoat layer)
The undercoat layer 2 is formed on the surface of the conductive support. In the present embodiment, the undercoat layer 2 includes a conductive metal oxide and an electron accepting substance. The undercoat layer 2 may contain a binder resin as necessary.

-Binder resin-
As the binder resin contained in the undercoat layer 2, a known resin can be used as long as a favorable film is formed and desired characteristics can be obtained. For example, acetal resin such as polyvinyl butyral, polyvinyl alcohol resin, casein, polyamide resin, cellulose resin, gelatin, polyurethane resin, polyester resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinyl acetate resin, vinyl chloride-vinyl acetate Known polymer resin compounds such as maleic anhydride resin, silicone resin, silicone-alkyd resin, phenol resin, phenol-formaldehyde resin, melamine resin, urethane resin, charge transporting resin having a charge transporting group, polyaniline, etc. A conductive resin or the like is used. Among these, resins that are insoluble in the upper coating solvent are preferably used, and phenol resins, phenol-formaldehyde resins, melamine resins, urethane resins, epoxy resins, and the like are particularly preferable.

-Conductive metal oxide particles-
Undercoat layer 2 includes conductive metal oxide particles (abbreviated as “metal oxide particles” where appropriate). The metal oxide particles contained in the undercoat layer 2 are desirably used in the range of 10% by mass to 80% by mass. More desirably, the metal oxide particles are used in the range of 30% by mass to 60% by mass. If the content of the metal oxide particles in the undercoat layer 2 is 10% by mass or more, the charge transfer in the undercoat layer is sufficiently performed, and residual charges are difficult to accumulate, and the surface of the conductive support 1 is not easily accumulated. It is suppressed that an electric field is applied and the surface of the support 1 is deteriorated.
In addition, when the content of the metal oxide particles in the undercoat layer 2 is 80% by mass or less, the metal oxide particles are hardly aggregated, and the metal oxide is excellent in the undercoat layer 2 when the undercoat layer is formed. A conductive path is formed, deterioration of sustainability such as an increase in residual potential is suppressed during repeated use, and image quality defects such as black spots are hardly caused.

As the metal oxide particles used in the present embodiment, powder having a volume resistivity of 10 ² Ω · cm to 10 ¹¹ Ω · cm is desirably used. The reason is that it is necessary for the undercoat layer 2 to obtain an appropriate resistance for obtaining leak resistance. If the volume resistivity of the metal oxide particles is lower than 10 ² Ωcm, sufficient leakage resistance cannot be obtained. If the volume resistivity is higher than 10 ¹¹ Ωcm, there is a possibility that the residual potential is increased.
Among them, it is desirable to use metal oxide particles such as tin oxide, titanium oxide, zinc oxide, and zirconium oxide having the volume resistivity. In particular, zinc oxide is desirably used.
The volume average particle diameter of the metal oxide particles is desirably in the range of 50 nm to 200 nm.

  The metal oxide particles in this embodiment may be subjected to a surface treatment. The surface treatment agent is selected from known materials capable of obtaining desired characteristics such as a silane coupling agent, a titanate coupling agent, an aluminum coupling agent, and a surfactant. In particular, silane coupling agents are desirably used because they give good electrophotographic characteristics. Further, a silane coupling agent having an amino group is desirably used because it gives the undercoat layer 2 good blocking properties.

Any silane coupling agent having an amino group may be used as long as it can obtain desired photoreceptor characteristics. Specific examples include γ-aminopropyltriethoxysilane, N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropylmethyldimethoxysilane, N, N. Examples include -bis (β-hydroxyethyl) -γ-aminopropyltriethoxysilane, but are not limited thereto.
Two or more silane coupling agents may be mixed and used. Examples of the silane coupling agent used in combination with the silane coupling agent having an amino group include vinyltrimethoxysilane, γ-methacryloxypropyl-tris (β-methoxyethoxy) silane, β- (3,4 -Epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β- (aminoethyl) -γ -Aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropylmethyldimethoxysilane, N, N-bis (β-hydroxyethyl) -γ-aminopropyltriethoxysilane, γ-chloropropyltrimethoxy Examples include silane, etc. The present invention is not limited.

As the surface treatment method, any known method can be used, and a dry method or a wet method is used.
When surface treatment is performed by a dry method, a silane coupling agent dissolved directly or in an organic solvent is dropped (added) or dried while stirring the metal oxide particles with a mixer having a large shearing force. The whole particles are treated by spraying with air or nitrogen gas. When adding or spraying a silane coupling agent dissolved in an organic solvent, it is desirable to carry out at a temperature below the boiling point of the solvent. When spraying at a temperature equal to or higher than the boiling point of the solvent, the solvent evaporates before it is sufficiently stirred, and the silane coupling agent is locally accumulated, so that the treatment tends to vary. After adding or spraying the silane coupling agent, baking is further performed at 100 ° C. or higher. Baking is performed at a temperature and a time at which desired electrophotographic characteristics can be obtained.

  As a wet method, the metal oxide particles are stirred in a solvent, dispersed using ultrasonic waves, a sand mill, an attritor, a ball mill, etc., added with a silane coupling agent solution, stirred or dispersed, and then the solvent is removed. The whole particle is processed. The solvent is distilled off by filtration or distillation. After removing the solvent, baking is further performed at 100 ° C. or higher. Baking is performed at a temperature and a time at which desired electrophotographic characteristics can be obtained. In the wet method, the moisture contained in the metal oxide particles may be removed before adding the surface treatment agent. For example, the method of removing with stirring and heating in the solvent used for the surface treatment, azeotroping with the solvent. Alternatively, the removal method may be used.

The amount of the silane coupling agent relative to the metal oxide particles in the undercoat layer 2 is set to an amount that provides desired electrophotographic characteristics.
The ratio between the metal oxide particles and the binder resin in the coating solution for forming the undercoat layer is set within a range in which desired electrophotographic photoreceptor characteristics can be obtained.

-Electron acceptor-
The undercoat layer 2 in the present embodiment contains an electron accepting substance (acceptor compound) in addition to the metal oxide particles. By containing the electron accepting substance, electrons are accumulated in the undercoat layer.

  The electron-accepting substance contained in the undercoat layer 2 desirably has a group that reacts with the metal oxide particles, and has an anthraquinone structure represented by the following general formula (1) from the viewpoint of preventing residual potential accumulation. Compounds are more desirable.

In formula (1), R ^{1 to} R ⁸ are each independently a hydrogen atom, halogen atom, hydroxyl group, amino group, substituted or unsubstituted alkyl group, substituted or unsubstituted alkoxy group, substituted or unsubstituted aryl group Or a carboxyl group.

  As the electron accepting substance, a compound containing an anthraquinone structure having a hydroxyl group is particularly preferably used. Examples of the compound containing an anthraquinone structure having a hydroxyl group include a hydroxyanthraquinone compound and an aminohydroxyanthraquinone compound, and any of these is desirably used. More specifically, alizarin, quinizarin, anthracine, purpurin, 1-hydroxyanthraquinone, 2-amino-3-hydroxyanthraquinone, 1-amino-4-hydroxyanthraquinone, 1,2-dihydroxy-4-ethoxy-anthraquinone, etc. Particularly desirable.

The content of the electron-accepting substance in the undercoat layer 2 (including those that are partly in the form of molecules) is preferably in the range of 0.004% by mass or more and 16% by mass or less, and 0.02% by mass or more. A range of 8% by mass or less is more desirable.
If the content of the electron-accepting substance in the undercoat layer 2 is less than 0.004% by mass, the surface of the undercoat layer is exposed even if the electron-accepting substance is dispersed in the undercoat layer 2 as a solid content. The amount is not sufficient, and the charge transfer from the photosensitive layer 3 may not be performed smoothly. On the other hand, when it exceeds 16 mass%, the dispersion state of solid content becomes non-uniform | heterogenous and may cause a black spot.

  Further, the electron accepting substance contained in the undercoat layer 2 is preferably 0.01 parts by mass or more and 20 parts by mass or less, more preferably 100 parts by mass of the metal oxide particles with respect to 100 parts by mass of the metal oxide particles. The range is 0.05 parts by mass or more and 10 parts by mass or less. If the electron-accepting substance is 0.01 parts by mass or more with respect to 100 parts by mass of the metal oxide particles, sufficient acceptor properties that contribute to the improvement of charge accumulation in the undercoat layer 2 are imparted, and during repeated use It is difficult to cause deterioration of maintainability such as an increase in residual potential. Further, when the amount of the electron accepting substance is 20 parts by mass or less with respect to 100 parts by mass of the metal oxide particles, it is difficult to cause aggregation between the metal oxide particles, and the metal oxide is formed in the undercoat layer 2 when the undercoat layer is formed. In addition to forming a good conductive path, it is difficult to cause deterioration of maintainability such as an increase in residual potential during repeated use, and it is difficult to cause image quality defects such as black spots.

-Other additives-
Various additives may be used in the coating solution for forming the undercoat layer in order to improve electrical characteristics, environmental stability, and image quality.
Examples of the additive include quinone compounds such as chloranil and bromoanil, tetracyanoquinodimethane compounds, 2,4,7-trinitrofluorenone, 2,4,5,7-tetranitro-9-fluorenone and the like. Fluorenone compounds, 2- (4-biphenyl) -5- (4-t-butylphenyl) -1,3,4-oxadiazole and 2,5-bis (4-naphthyl) -1,3,4-oxa Oxadiazole compounds such as diazole and 2,5-bis (4-diethylaminophenyl) -1,3,4-oxadiazole, xanthone compounds, thiophene compounds, 3,3 ′, 5,5′-tetra Electron transporting substances such as diphenoquinone compounds such as t-butyldiphenoquinone, electron transporting pigments such as polycyclic condensation systems and azo systems, zirconium chelate compounds, titania Chelate compounds, aluminum chelate compounds, titanium alkoxide compounds, organic titanium compounds, known materials such as a silane coupling agent.

  As described above, the silane coupling agent is used for the surface treatment of the metal oxide particles, but may be further added to the coating solution for forming the undercoat layer as an additive. Specific examples of the silane coupling agent used here include vinyltrimethoxysilane, γ-methacryloxypropyl-tris (β-methoxyethoxy) silane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ. -Glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, N-β -(Aminoethyl) -γ-aminopropylmethyldimethoxysilane, N, N-bis (β-hydroxyethyl) -γ-aminopropyltriethoxysilane, γ-chloropropyltrimethoxysilane and the like.

  Examples of the zirconium chelate compound include zirconium butoxide, zirconium zirconium acetoacetate, zirconium triethanolamine, acetylacetonate zirconium butoxide, ethyl acetoacetate butoxide, zirconium acetate, zirconium oxalate, zirconium lactate, zirconium phosphonate, octane. Zirconate, zirconium naphthenate, zirconium laurate, zirconium stearate, zirconium isostearate, methacrylate zirconium butoxide, stearate zirconium butoxide, isostearate zirconium butoxide and the like.

  Examples of the titanium chelate compound include tetraisopropyl titanate, tetranormal butyl titanate, butyl titanate dimer, tetra (2-ethylhexyl) titanate, titanium acetylacetonate, polytitanium acetylacetonate, titanium octylene glycolate, and titanium lactate ammonium. Examples thereof include salts, titanium lactate, titanium lactate ethyl ester, titanium triethanolamate, and polyhydroxytitanium stearate.

Examples of the aluminum chelate compound include aluminum isopropylate, monobutoxy aluminum diisopropylate, aluminum butyrate, diethyl acetoacetate aluminum diisopropylate, aluminum tris (ethyl acetoacetate) and the like.
These compounds are used alone or as a mixture or polycondensate of a plurality of compounds.

  As the solvent for preparing the coating solution for forming the undercoat layer, any known organic solvent such as alcohol, aromatic, halogenated hydrocarbon, ketone, ketone alcohol, ether, ester, etc. Selected. For example, methanol, ethanol, n-propanol, iso-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, ethyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, Usual organic solvents such as methylene chloride, chloroform, chlorobenzene and toluene are used.

These solvents may be used alone or in combination of two or more. Any solvent can be used as long as it is a solvent that dissolves the binder resin as a mixed solvent.
In selecting the solvent, a solvent (poor solvent) having poor solubility of the electron-accepting substance is used in order to leave the electron-accepting substance dispersed in the undercoat layer as a solid. Is desirable. Since electron-accepting substances are generally highly polar, they are often poorly soluble in nonpolar solvents. As the nonpolar solvent, hydrocarbon solvents such as hexane, octane and cyclohexane are desirably used. Moreover, when mixing and using the said 2 or more types of solvent, it is desirable to mix | blend so that the said nonpolar solvent may become main.

In the present embodiment, the undercoat layer forming coating solution is prepared by selecting an optimal solvent for solidifying the electron-accepting substance, and adding appropriate amounts of the electron-accepting substance, the binder resin, and the metal oxide particles. Mix with. In this case, after the binder resin is first dissolved in the solvent, the electron accepting substance and the metal oxide particles may be added.
As a method for dispersing the electron-accepting substance after mixing these, known methods such as a roll mill, a ball mill, a vibrating ball mill, an attritor, a sand mill, a colloid mill, and a paint shaker are used.

In the present embodiment, it is desirable to disperse the solid substance of the electron accepting substance throughout the undercoat layer, and from this point of view, it is desirable to disperse for a predetermined time or more with a predetermined shear force.
As the dispersion condition, for example, in the case of dispersion by a sand mill using glass beads having a diameter of 1 mm (filling ratio: 70% or more and 95% or less), it is desirable to disperse in 0.1 hours or more and 100 hours or less.

  Coating methods used when the undercoat layer 2 is provided on the conductive support 1 include blade coating, wire bar coating, spray coating, dip coating, bead coating, air knife coating, and curtain coating. Ordinary methods such as are used.

In the case where the metal oxide particles and the electron accepting substance are reacted, even if the metal oxide particles and the electron accepting substance that reacts with the metal oxide particles react in the dispersion step, the coating film Although it may react during drying and curing, it is desirable to react in a dispersion because it reacts evenly.
Using the coating solution for forming the undercoat layer thus obtained, it is applied on a conductive support and dried to form the undercoat layer 2.
The formed undercoat layer 2 preferably has a Vickers hardness of 35 or more.

The volume resistivity of the undercoat layer 2 is preferably in the range of 10 ⁶ Ωcm to 10 ¹³ Ωcm, and more preferably in the range of 10 ⁸ Ωcm to 10 ¹¹ Ωcm. If the volume resistivity is less than 10 ⁶ Ωcm, the charging potential may not be sufficient or leakage may occur. On the other hand, if it exceeds 10 ¹³ Ωcm, stable potential characteristics may not be obtained by repeated use. Furthermore, the volume resistivity is more preferably in the range of 10 ⁸ Ωcm or more and 10 ¹¹ Ωcm or less from the viewpoint of sufficiently exhibiting the effect of exposure before starting image formation.
The volume resistivity of the undercoat layer 2 is high in the range of 1 Vp-p AC voltage from 1 MHz to 1 mHz with a conductive support such as an aluminum pipe in the impedance measurement sample as a cathode and a gold electrode as an anode. Apply from the frequency and measure the AC impedance of each sample. It is measured by a method of obtaining volume resistivity by fitting a graph of a Cole-Cole plot obtained by this measurement to an RC parallel circuit.

  The volume resistivity of the undercoat layer 2 is adjusted by the type, concentration, dispersion state, etc. of the conductive metal oxide particles. For example, even when the conductive metal oxide particles and the electron-accepting material are contained in the coating solution for forming the undercoat layer, the components contained in the coating solution and the content are the same. The volume resistivity of the undercoat layer 2 is adjusted by changing the dispersion state of the metal oxide particles and the like according to time. Usually, the volume resistivity of the undercoat layer 2 tends to increase as the dispersion time is increased. Therefore, when the volume resistivity is relatively small, the dispersion time may be shortened.

  The thickness of the undercoat layer 2 may be set to any thickness as long as desired characteristics can be obtained, but the thickness is preferably 15 μm or more, and more preferably 15 μm or more and 50 μm or less. desirable. If the thickness of the undercoat layer 2 is 15 μm or more, sufficient leakage resistance can be obtained, and if it is 50 μm or less, the residual potential hardly remains during long-term use.

Further, the surface roughness of the undercoat layer 2 is adjusted to ¼n (n is the refractive index of the upper layer) or more and ½λ or less of the exposure laser wavelength λ to be used to prevent moire images. In order to adjust the surface roughness, particles such as a resin may be added to the undercoat layer. As the resin particles, silicone resin particles, cross-linked PMMA resin particles, and the like are used.
Further, the undercoat layer 2 may be polished for adjusting the surface roughness. Examples of the polishing method include buffing, sandblasting, wet honing, and grinding.

(Middle layer)
In the electrophotographic photosensitive member of this embodiment, an intermediate layer is further provided between the undercoat layer 2 and the photosensitive layer 3 in order to improve electrical characteristics, improve image quality, improve image quality maintenance, improve adhesion to the photosensitive layer, and the like. 4 may be provided.
The intermediate layer 4 includes an acetal resin such as polyvinyl butyral, polyvinyl alcohol resin, casein, polyamide resin, cellulose resin, gelatin, polyurethane resin, polyester resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinyl acetate resin, vinyl chloride. -Organic metals containing zirconium, titanium, aluminum, manganese, silicon atoms, etc. in addition to polymer resin compounds such as vinyl acetate-maleic anhydride resin, silicone resin, silicone-alkyd resin, phenol-formaldehyde resin, melamine resin A compound or the like is used. These compounds are used alone or as a mixture or polycondensate of a plurality of compounds. Among these, organometallic compounds containing zirconium or silicon are excellent in performance, such as low residual potential, little potential change due to environment, and little potential change due to repeated use.

  Examples of silicon compounds include vinyltrimethoxysilane, vinyltris (2-methoxyethoxysilane), γ-methacryloxypropyl-tris (β-methoxyethoxy)) silane, γ-methacryloxypropyltrimethoxysilane, β- (3 , 4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β- (aminoethyl) -Γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropylmethyldimethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N, N-bis (β-hydroxyethyl)- γ-aminopropyltri Tokishishiran a γ- chloropropyl trimethoxysilane.

  Of these, silicon compounds particularly preferably used are vinyltriethoxysilane, vinyltris (2-methoxyethoxysilane), γ-methacryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, β- (3,4). -Epoxycyclohexyl) ethyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropylmethyldimethoxysilane, γ-aminopropyltriethoxysilane And silane coupling agents such as N-phenyl-3-aminopropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, and γ-chloropropyltrimethoxysilane.

  Examples of organic zirconium compounds include zirconium butoxide, zirconium zirconium acetoacetate, zirconium triethanolamine, acetylacetonate zirconium butoxide, ethyl acetoacetate butoxide, zirconium acetate, zirconium oxalate, zirconium lactate, zirconium phosphonate, zirconium octoate, Zirconium naphthenate, zirconium laurate, zirconium stearate, zirconium isostearate, methacrylate zirconium butoxide, stearate zirconium butoxide, isostearate zirconium butoxide and the like.

  Examples of organic titanium compounds include tetraisopropyl titanate, tetranormal butyl titanate, butyl titanate dimer, tetra (2-ethylhexyl) titanate, titanium acetylacetonate, polytitanium acetylacetonate, titanium octylene glycolate, titanium lactate ammonium salt , Titanium lactate, titanium lactate ethyl ester, titanium triethanolamate, polyhydroxy titanium stearate and the like.

  Examples of organoaluminum compounds include aluminum isopropylate, monobutoxy aluminum diisopropylate, aluminum butyrate, diethyl acetoacetate aluminum diisopropylate, aluminum tris (ethyl acetoacetate) and the like.

  The intermediate layer 4 plays the role of an electrical blocking layer in addition to improving the coatability of the upper layer. However, when the film thickness is too large, the electrical barrier becomes too strong and the potential increases due to desensitization or repetition. cause. Therefore, when the intermediate layer 4 is formed, the film thickness range is set to 0.1 μm or more and 5 μm or less.

(Charge generation layer)
The charge generation layer 31 is formed by 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, and other selenium compounds; inorganic photoconductors such as selenium alloy, zinc oxide, and titanium oxide; Sensitized, various phthalocyanine compounds such as metal-free phthalocyanine, titanyl phthalocyanine, copper phthalocyanine, tin phthalocyanine, gallium phthalocyanine; squalium, anthrone, perylene, azo, anthraquinone, pyrene, pyrylium salt, thiapyrylium Various organic pigments such as salts; or dyes are used.

In addition, these 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 may be used as long as it is a pigment capable of obtaining characteristics.
Of the charge generation materials described above, phthalocyanine compounds are preferred. In this case, when the photosensitive layer is irradiated with light, the phthalocyanine compound contained in the photosensitive layer absorbs photons and generates carriers. At this time, since the phthalocyanine compound has high quantum efficiency, the absorbed photons are efficiently absorbed to generate carriers.

  Examples of the binder resin used for the charge generation layer 31 include the following. That is, polycarbonate resin such as bisphenol A type or bisphenol Z type and copolymers thereof, polyarylate resin, polyester resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polystyrene resin, polyvinyl acetate resin, styrene-butadiene copolymer Resin, 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, etc. .

These binder resins are 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 preferably in the range of 10: 1 to 1:10 by mass ratio. The thickness of the charge generation layer is generally preferably in the range of 0.01 μm to 5 μm, and more preferably in the range of 0.05 μm to 2.0 μm.

Further, the charge generation layer 31 may contain at least one electron accepting substance for the purpose of improving sensitivity, reducing residual potential, reducing fatigue during repeated use, and the like. Examples of the electron accepting material used for the charge generation layer 31 include succinic anhydride, maleic anhydride, dibromomaleic anhydride, phthalic anhydride, tetrabromophthalic anhydride, tetracyanoethylene, tetracyanoquinodimethane, o-di Examples thereof include nitrobenzene, m-dinitrobenzene, chloranil, dinitroanthraquinone, trinitrofluorenone, picric acid, o-nitrobenzoic acid, p-nitrobenzoic acid and phthalic acid. Of these, fluorenone-based, quinone-based, and benzene derivatives having electron-withdrawing substituents such as Cl, CN, NO ₂ are particularly preferable.

  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 can be used.

  Examples of the solvent for the coating solution for forming the charge generation layer 31 include known organic solvents such as aromatic hydrocarbon solvents such as toluene and chlorobenzene, methanol, ethanol, n-propanol, iso-propanol, and n-butanol. Aliphatic alcohol solvents such as acetone, ketone solvents such as acetone, cyclohexanone and 2-butanone, halogenated aliphatic hydrocarbon solvents such as methylene chloride, chloroform and ethylene chloride, cyclic such as tetrahydrofuran, dioxane, ethylene glycol and diethyl ether Alternatively, linear ether solvents, ester solvents such as methyl acetate, ethyl acetate, and n-butyl acetate can be used.

(Charge transport layer)
The charge transport layer 32 is formed of a known material, and may be formed using a charge transport material and a binder resin, or may be formed using a polymer charge transport material.
Charge transport materials include quinone compounds such as p-benzoquinone, chloranil, bromanyl, anthraquinone, tetracyanoquinodimethane compounds, fluorenone compounds such as 2,4,7-trinitrofluorenone, xanthone compounds, benzophenone compounds , Electron transport compounds such as cyanovinyl compounds and ethylene compounds, triarylamine compounds, benzidine compounds, arylalkane compounds, aryl-substituted ethylene compounds, stilbene compounds, anthracene compounds, hydrazone compounds, etc. Examples thereof include pore transporting compounds.
These charge transport materials may be used alone or in combination of two or more, but are not limited thereto.

The binder resin used for the charge transport layer 32 is 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- Polymeric charge transport materials such as vinyl carbazole, polysilane, and polyester-based polymer charge transport materials disclosed in JP-A-8-176293 and JP-A-8-208820 may be used. More preferably, it is a polycarbonate-based resin, and a copolymer including a plurality of polycarbonate structures may be used.
These binder resins may be used alone or in combination of two or more.
The blending ratio (mass ratio) of the charge transport material and the binder resin is preferably 10: 1 to 1: 5.

  Moreover, you may use a polymeric charge transport material independently. The polymer charge transport material alone may form a charge transport layer, or may be mixed with the binder resin to form a charge transport layer.

The thickness of the charge transport layer 32 is generally preferably 5 μm or more and 50 μm or less, and more preferably 9 μm or more and 28 μm or less.
As a coating method of the coating solution for forming the charge transport layer, usual methods such as a blade coating method, a Meyer bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method, and a curtain coating method are used. .
Solvents used when the charge transport layer 32 is provided include 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. Ordinary organic solvents such as aliphatic hydrocarbons, cyclic ethers such as tetrahydrofuran and ethyl ether, or straight chain ethers are used alone or in admixture of two or more.

  Additives such as antioxidants, light stabilizers, heat stabilizers, etc. in the photosensitive layer for the purpose of preventing deterioration of the electrophotographic photoreceptor due to ozone, oxidizing gas, or light and heat generated in the copying machine Can be added. 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, for the purpose of improving sensitivity, reducing residual potential, reducing fatigue during repeated use, etc., the charge transport layer 32 may contain at least one electron accepting substance. Examples of the electron acceptor include succinic anhydride, maleic anhydride, dibromomaleic anhydride, phthalic anhydride, tetrabromophthalic anhydride, tetracyanoethylene, tetracyanoquinodimethane, o-dinitrobenzene, m-dinitrobenzene, Examples include 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 preferable.

  Further, various particles may be added in order to improve the antifouling substance adhesion and lubricity on the surface of the electrophotographic photosensitive member. They can be used alone or in combination. Examples of the particles are shown in Fluorine-based particles such as tetrafluoroethylene, trifluoride ethylene, propylene hexafluoride, vinyl fluoride, vinylidene fluoride, and “8th Polymer Materials Forum Lecture Proceedings p89”. Such particles are made of a resin obtained by copolymerizing the fluororesin and a monomer having a hydroxyl group.

  For the same purpose, an 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, Examples thereof include reactive silicone oils such as methacryl-modified polysiloxane, mercapto-modified polysiloxane, and phenol-modified polysiloxane.

(Protective layer)
The protective layer 5 is necessary to prevent chemical changes of the charge transport layer 32 during charging, to improve the mechanical strength of the photosensitive layer 3, and to further improve the resistance to surface abrasion, scratches, and the like. Provided accordingly.

Examples of the form of the protective layer 5 include a cured resin film including a curable resin and a charge transporting compound, a film formed by containing a conductive material in a suitable binder resin, and the like. What is contained is more desirably used.
A known resin is used as the curable resin, but in particular, from the viewpoint of strength, electrical characteristics, image quality maintenance, and the like, those having a crosslinked structure are desirable. For example, phenol resin, urethane resin, melamine resin, diallyl phthalate resin, Examples thereof include siloxane resins.

Further, other compounds that undergo a crosslinking reaction may be used in combination. As such a compound, various silane coupling agents and commercially available silicon hard coat agents may be used.
As silane coupling agents, vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxy Silane, γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropylmethyldimethoxysilane, N-β (aminoethyl) γ-aminopropyltriethoxysilane, tetramethoxysilane, methyltrimethoxysilane, Examples include dimethyldimethoxysilane.

  As a commercially available hard coat agent, KP-85, CR-39, X-12-2208, X-40-9740, X-41-1007, KNS-5300, X-40-2239 (above, manufactured by Shin-Etsu Silicone Co., Ltd.) ), AY42-440, AY42-441, AY49-208 (manufactured by Toray Dow Corning Co., Ltd.), and the like.

  Further, a fluorine atom-containing compound may be added to the protective layer 5 for the purpose of imparting surface lubricity. By improving the surface lubricity, the coefficient of friction with the cleaning member is lowered, and the wear resistance is improved. Further, it also has an effect of preventing adhesion of discharge products, developer, paper dust, and the like to the surface of the electrophotographic photosensitive member, which is useful for improving the life of the electrophotographic photosensitive member 7.

  As a specific example of the fluorine-containing compound, a fluorine atom-containing polymer such as polytetrafluoroethylene may be added as it is, or particles of these polymers may be added.

Further, as the fluorine-containing compound, it is desirable to add a compound that reacts with alkoxysilane and configure it as a part of the crosslinked film.
Specific examples of such fluorine atom-containing compounds include (tridecafluoro-1,1,2,2-tetrahydrooctyl) triethoxysilane, (3,3,3-trifluoropropyl) trimethoxysilane, 3- ( Heptafluoroisopropoxy) propyltriethoxysilane, 1H, 1H, 2H, 2H-perfluoroalkyltriethoxysilane, 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane, 1H, 1H, 2H, 2H-perfluoro And octyltriethoxysilane.

The addition amount of the fluorine-containing compound is desirably 20% by mass or less. Beyond this, a problem may occur in the film formability of the crosslinked cured film.
The protective layer 5 has sufficient oxidation resistance, but an antioxidant may be added for the purpose of imparting stronger oxidation resistance.

  Antioxidants are preferably hindered phenols or hindered amines, organic sulfur antioxidants, phosphite antioxidants, dithiocarbamate antioxidants, thiourea antioxidants, benzimidazole antioxidants. , Etc., may be used. The addition amount of the antioxidant is preferably 15% by mass or less, and more preferably 10% by mass or less.

  Examples of the hindered phenol antioxidant include 2,6-di-t-butyl-4-methylphenol, 2,5-di-t-butylhydroquinone, N, N′-hexamethylene bis (3,5-di). -T-butyl-4-hydroxyhydrocinnamide, 3,5-di-t-butyl-4-hydroxy-benzylphosphonate-diethyl ester, 2,4-bis [(octylthio) methyl] -o-cresol, 2,6-di-t-butyl-4-ethylphenol, 2,2'-methylenebis (4-methyl-6-t-butylphenol), 2,2'-methylenebis (4-ethyl-6-t-butylphenol) 4,4'-butylidenebis (3-methyl-6-t-butylphenol), 2,5-di-t-amylhydroquinone, 2-t-butyl-6- (3-butyl-2- Dorokishi-5-methylbenzyl) -4-methylphenyl acrylate, 4,4'-butylidene bis (3-methyl -6-t-butylphenol), and the like.

  The protective layer 5 may contain other additives used for forming a known coating film, and known materials such as a leveling agent, an ultraviolet absorber, a light stabilizer, and a surfactant are used.

  In order to form the protective layer 5, a mixture of the above-described various materials and various additives is applied onto the photosensitive layer and heat-treated. Thereby, a cross-linking curing reaction is caused three-dimensionally to form a strong cured film. The temperature of the heat treatment is not particularly limited as long as it does not affect the underlying photosensitive layer, but is preferably set to room temperature (15 ° C.) or higher and 200 ° C. or lower, particularly 100 ° C. or higher and 160 ° C. or lower.

  In the formation of the protective layer 5, the crosslinking curing reaction may be performed without a catalyst, but an appropriate catalyst may be used. Catalysts include acid catalysts such as hydrochloric acid, sulfuric acid, phosphoric acid, formic acid, acetic acid, trifluoroacetic acid, bases such as ammonia and triethylamine, organic tin compounds such as dibutyltin diacetate, dibutyltin dioctoate, stannous oxalate, Examples thereof include organic titanium compounds such as tetra-n-butyl titanate and tetraisopropyl titanate, iron salts of organic carboxylic acids, manganese salts, cobalt salts, zinc salts, zirconium salts, and aluminum chelate compounds.

  In forming the protective layer 5, a solvent is added as necessary to facilitate application. Specifically, water, methanol, ethanol, n-propanol, i-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, Examples of the organic solvent include methylene chloride, chloroform, dimethyl ether, and dibutyl ether. You may use these individually by 1 type or in mixture of 2 or more types.

In forming the protective layer 5, as a coating method, a normal 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.
The thickness of the protective layer is preferably in the range of 0.5 μm to 20 μm, particularly in the range of 2 μm to 10 μm.

  The electrophotographic photoreceptor 7 according to the present embodiment is not limited to the above configuration. For example, the electrophotographic photoreceptor 7 may have a configuration in which the intermediate layer 4 and / or the protective layer 5 are not present. That is, the undercoat layer 2 and the photosensitive layer 3 are formed on the conductive support 1, and the undercoat layer 2, the intermediate layer 4, and the photosensitive layer 3 are sequentially formed on the conductive support 1. Alternatively, a structure in which the undercoat layer 2, the photosensitive layer 3, and the protective layer 5 are sequentially formed on the conductive support 1 may be used.

  In addition, the stacking order of the charge generation layer 31 and the charge transport layer 32 may be reversed. Further, the photosensitive layer 3 may have a single layer structure. In that case, a protective layer may be provided on the photosensitive layer, or both the undercoat layer 2 and the protective layer 5 may be provided. Further, the intermediate layer 4 may be provided on the undercoat layer 2 as described above.

<Charging means>
Examples of the charging device (charging means) 208 used in the present embodiment include a charging device using a non-contact charging method or a contact charging method, but from the viewpoint of power saving, only a DC voltage is applied, and electrophotography is performed. A charging unit having a charging member that contacts and charges the surface of the photoreceptor 7 is preferable.

Various known forms such as a roller, a brush, and a film are used as the contact charging type charging member, and a roller-shaped charging member is particularly desirable. The roller-shaped charging member is preferably in contact with the electrophotographic photosensitive member at a pressure of 250 mgf to 600 mgf.
The roller-shaped charging member is made of a material adjusted to an electric resistance (10 ³ Ω or more and 10 ⁸ Ω or less) effective as a charging member, and may be made of a single layer or a plurality of layers.

  Synthetic rubber such as urethane rubber, silicon rubber, fluorine rubber, chloroprene rubber, butadiene rubber, EPDM (ethylene-propylene-diene copolymer rubber), epichlorohydrin rubber, polyolefin, polystyrene, vinyl chloride, etc. The main material is an elastomer made of the above, and a suitable amount of a conductivity imparting agent such as conductive carbon, metal oxide, or ionic conductive agent is used. These materials can easily develop an effective electric resistance as a charging member.

  Furthermore, a resin such as nylon, polyester, polystyrene, polyurethane, silicone, etc. is made into a paint, and an appropriate amount of any conductivity imparting agent such as conductive carbon, metal oxide, ionic conductive agent, etc. is blended there, and the resulting paint is dipped. You may laminate | stack by arbitrary methods, such as a spray and a roll coat.

  On the other hand, for brush-shaped charging members, a conventional fiber-impregnated fiber such as acrylic, nylon, polyester, etc., is impregnated with fluorine, and then transplanted using an existing method, and brush-shaped charging is performed. You may produce a member. Further, after various fibers are formed on the brush-shaped charging member, fluorine impregnation treatment may be performed.

  The brush-like charging member referred to here may be any of a roller-shaped charging member and a brushed charging member, and the shape thereof is not particularly limited. Further, the magnetic brush-like charging member is a member in which ferrite, magite and the like having a magnetic force are radially arranged on the outer periphery of a cylinder containing a multipolar magnet. A brush is desirable.

<Exposure means>
The exposure apparatus (exposure unit) 210 used in the present embodiment exposes the surface of the electrophotographic photosensitive member 7 charged by the charging unit 208 to form an electrostatic latent image, and once the image formation is stopped, it is resumed. In this case, before charging the surface of the electrophotographic photosensitive member 7 by the charging unit 208, the surface of the electrophotographic photosensitive member 7 is used as means for exposing the entire surface.

As an exposure light source, for example, a laser beam emitted from a single light emitting laser element that forms a 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 used as a polygon mirror. Examples include those that refract and those in which a plurality of LED (Light Emitting Diode) elements are arranged linearly or in a staggered manner, but are not particularly limited.
The wavelength of the exposure light may be set according to the photosensitivity of the photoconductor 7, but a wavelength of 750 nm to 850 nm is usually used.

In the image formation, the exposure unit 210 writes an image by irradiating the photoconductor 7 with light corresponding to the writing image data from the image processing apparatus. The amount of light during image writing is preferably 0.5 mJ / m ² or more on the surface of the photoreceptor, and more preferably 0.5 mJ / m ² or more and 5.0 mJ / m ² or less.

On the other hand, when the image formation is temporarily stopped and resumed, before the surface of the electrophotographic photosensitive member 7 is charged by the charging unit 208, the entire exposure of the surface of the electrophotographic photosensitive member 7 by the exposing unit 210 (as necessary “Exposure” is performed on the entire surface of the photoconductor 7 while rotating the photoconductor 7 before starting image formation.
The amount of pre-exposure (pre-exposure intensity) when resuming image formation is preferably ³ mJ / m ² or more on the surface of the photoreceptor 7 from the viewpoint of removing the history of the previous cycle, and more preferably 4 mJ / m ² or more. It is preferable that it is 10 mJ / m ² or less.

  Note that the exposure conditions (exposure intensity, exposure time, etc.) by the exposure means 210 may be different at the time of image writing (at the time of forming an electrostatic latent image) and at the time of pre-exposure.

<Developing means>
The developing device (developing unit) 211 used in the present embodiment is particularly suitable if it contains a developer containing toner and develops an electrostatic latent image formed on the surface of the photoreceptor to form a toner image. It is not limited. For example, a two-component developing type developing means for developing a developing brush made of carrier and toner in contact with the electrophotographic photosensitive member, or an electrophotographic photosensitive member by attaching toner on a conductive rubber elastic material transporting roll (developing roll) For example, a developing unit of a contact type one-component developing method in which toner is applied to the toner 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 electrophotographic photosensitive member, and if a peripheral speed difference is made in the opposite direction to the electrophotographic photosensitive member, The residual toner recoverability is improved. The electric field applied to the developing roll may be a direct current or an alternating current superimposed on the direct current.

  Further, in order to improve the toner recoverability and the discharge product scraping property, the magnetic brush formed on the surface of the developing roll has a layer regulating member so that the density of the magnetic brush facing the electrophotographic photosensitive member is constant. It is preferable that the magnetic brush density is adjusted within an appropriate range by controlling the layer.

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

-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 as necessary.
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, manganese, an alloy, or a compound containing these metals may be included. Further, if necessary, a charge control agent usually used such as a quaternary ammonium salt, a nigrosine compound or a triphenylmethane pigment may be appropriately 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 exemplary 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, emulsification A toner production method by a known polymerization method such as a 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 in the range of toner: carrier = 1: 100 to 30: 100, and 3: 100 to 20: 100. A range of the degree is more preferable.

<Transfer means>
As the transfer device (transfer means) 212 used in this embodiment, a device using a known transfer system is used. For example, a direct transfer method using a transfer corotron or a transfer roll, an intermediate transfer method using an intermediate transfer member such as an intermediate transfer belt or an intermediate transfer drum, or an electrophotographic photosensitive member that electrostatically adsorbs and conveys a recording medium Examples thereof include a transfer means using a transfer belt method for transferring the above toner image.

<Cleaning means>
As the cleaning device (cleaning means) 213 used in the present embodiment, a known cleaning method is used. For example, when a cleaning blade is used, the portion of the cleaning blade that contacts the surface of the electrophotographic photosensitive member is made of an elastic member, and the 100% modulus of the elastic member is preferably 6.5 MPa or more, and is 7.0 MPa or more. More preferably, it is 9.0 MPa or more. When the 100% modulus of the elastic member is less than 6.5 MPa, the hardness is lowered and the dynamic deflection of the cleaning blade is increased, so that it is difficult to suppress uneven wear of the electrophotographic photosensitive member. On the other hand, when the 100% modulus of the elastic member is too large, the followability of the cleaning blade to the electrophotographic photosensitive member may deteriorate, and good cleaning properties may not be obtained. Therefore, 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 elastic material is used, and other materials may be added as necessary. The rubber elastic material is not particularly limited, and urethane rubber, silicone rubber, acrylic rubber, acrylonitrile rubber, butadiene rubber, styrene rubber, or a composite material thereof is used.
In addition, a plate shape is preferably used as the shape of the substrate of the cleaning blade, and it is formed using centrifugal molding, extrusion molding, mold molding, or the like.

<Image forming method>
Next, an image forming method using the image forming apparatus 200 according to the present embodiment will be described.
In the image forming apparatus 200 according to the present embodiment, when a control unit (not shown) receives a signal for restarting image formation, the electrophotographic photosensitive member 7 is rotated. Then, before charging the surface of the photoconductor 7 by the charging device 208, the entire surface of the photoconductor 7 is exposed by a predetermined exposure amount by the exposure device 210 (pre-exposure step).
Note that the pre-exposure by the exposure apparatus 210 does not have to be performed for every cycle, that is, for each image formation, and is performed only before charging for the first image formation after the image formation of the previous cycle is stopped.

After pre-exposure, the surface of the photoconductor 7 is charged by the charging device 208 (charging process).
The surface of the photoreceptor 7 charged by the charging device is exposed by the exposure device 210 based on the image data to form an electrostatic latent image (electrostatic latent image forming step).
When the area where the electrostatic latent image is formed on the surface of the photoconductor 7 reaches the position where the developing device 211 is provided by the rotation of the photoconductor 7, the electrostatic latent image is generated by the toner supplied from the developing device 211. Is developed to form a toner image (development process).

Further, when the area where the toner image is formed on the photoconductor 7 reaches the position where the transfer device 212 is provided by the rotation of the photoconductor 7, the recording carried by the transfer device 212 by the transport device (not shown). The toner image on the photoreceptor 7 is transferred to the medium 500 (transfer process).
When the recording medium 500 to which the toner image is transferred is conveyed by a conveying device (not shown) and reaches a position where the fixing device 215 is provided, the recording medium 500 is fixed by the fixing device 215 and an image is formed on the recording medium 500. Is formed (fixing step).
Then, foreign matters such as toner remaining on the photosensitive member 7, adhered carrier, paper dust and the like are removed by the cleaning member of the cleaning device 213 (cleaning step).

In the above embodiment, the toner image formed on the photoconductor 7 is directly transferred to the recording medium 500. However, after the toner image formed on the photoconductor 7 is primarily transferred to the intermediate transfer body. An image forming apparatus that performs secondary transfer from the intermediate transfer member to the recording medium may be used.
For example, a tandem image forming apparatus in which four electrophotographic photosensitive members are arranged in parallel with each other along the intermediate transfer belt to form a color image may be used.

  The recording medium referred to in the present embodiment is not limited to paper, and is not particularly limited as long as it is a medium that transfers a toner image formed in the shape of an electrophotographic photosensitive member.

  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)
100 parts by mass of zinc oxide (average particle size: 70 nm, manufactured by Teica, specific surface area value: 15 m ² / g) is stirred and mixed with 500 parts by mass of methanol, and KBM603 (manufactured by Shin-Etsu Chemical Co., Ltd.) is used as a silane coupling agent. 25 parts by mass was 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 by mass of the surface-treated zinc oxide particles, 0.6 parts by mass of alizarin, 13.5 parts by mass of blocked isocyanate (Sumidule 3173, manufactured by Sumitomo Bayern Urethane Co., Ltd.) as a curing agent, and butyral resin (BM-1, manufactured by Sekisui Chemical Co., Ltd.) 15 parts by mass, 38 parts by mass of a solution obtained by dissolving 85 parts by mass of methyl ethyl ketone and 25 parts by mass of methyl ethyl ketone are mixed, and 4 hours in a sand mill using glass beads having a diameter of 1 mm. Was dispersed to obtain a dispersion.

  To the obtained dispersion, 0.005 parts by mass of dioctyltin dilaurate and 4.0 parts by mass of silicone resin particles (Tospearl 145, manufactured by GE Toshiba Silicone) are added as a catalyst, and a coating liquid for forming an undercoat layer is added. Obtained. This coating solution was applied on an aluminum substrate having a diameter of 30 mm by a dip coating method, followed by drying and curing at 180 ° C. for 40 minutes to obtain an undercoat layer having a thickness of 25 μm.

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

  Next, 8 parts by mass of tetrafluoroethylene resin particles (average particle size: 0.2 μm) and 0.01 parts by mass of a fluorinated alkyl group-containing methacrylic copolymer (weight average molecular weight: 30000), 4 parts by mass of tetrahydrofuran, and toluene The mixture was kept at a liquid temperature of 20 ° C. together with 1 part by mass and stirred for 48 hours to obtain a tetrafluoroethylene resin particle suspension A.

  Next, 4 parts by mass of tris [4- (4,4-diphenyl-1,3-butadienyl) phenyl] amine as a charge transport material and a bisphenol Z-type polycarbonate resin (viscosity average molecular weight: 40,000) as a binder resin 6 parts by mass and 0.1 part by mass of 2,6-di-t-butyl-4-methylphenol as an antioxidant were mixed and 24 parts by mass of tetrahydrofuran and 11 parts by mass of toluene were mixed and dissolved. Got.

After the A liquid was added to the B liquid and stirred and mixed, the pressure was 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. 5 ppm of fluorine-modified silicone oil (trade name: FL-100 manufactured by Shin-Etsu Silicone Co., Ltd.) was added to the solution obtained by repeating the dispersion treatment six times, and the mixture was sufficiently stirred to obtain a coating solution for forming a charge transport layer.

  This coating solution was applied onto the charge generation layer and dried at 135 ° C. for 25 minutes to form a charge transport layer having a thickness of 20 μm, thereby obtaining the intended electrophotographic photosensitive member. The electrophotographic photoreceptor thus obtained was designated as photoreceptor 1.

(Measurement of volume resistivity of undercoat layer)
The volume resistivity of the undercoat layer was measured by the following method.
SI 1287 electrochemical interface (manufactured by Toyo Technica) was used as a power source, SI 1260 impedance / gain phase analyzer (manufactured by Toyo Technica) was used as an ammeter, and 1296 dielectric interface (manufactured by Toyo Technica) was used as a current amplifier.
Using the aluminum pipe in the impedance measurement sample as the cathode and the gold electrode as the anode, an AC voltage of 1 Vp-p is applied from a high frequency in the frequency range of 1 MHz to 1 mHz, and the AC impedance of each sample is measured. The volume resistivity was obtained by fitting the obtained Cole-Cole plot graph to an RC parallel equivalent circuit.

(Evaluation of ghost images)
The photoreceptor 1 was incorporated into a modified DocuCenter 505a (manufactured by Fuji Xerox Co., Ltd.) that is not equipped with a static eliminator, and image formation was performed.
Specifically, image formation was performed as follows, and the occurrence of ghost was evaluated.
A print test was conducted under conditions of no static elimination and low temperature and low humidity. Here, the low temperature and low humidity is an ambient environment at 10 ° C. and 15 RH%. A solid black image was taken in the first cycle of the photoconductor, a 30% halftone image was taken in the second cycle, and a grade evaluation was performed on the remaining half of the history of the first cycle in the second cycle halftone image. The evaluation criteria are as follows.
G0: No history remaining in the first cycle G + 0.5: Intermediate G + 1 between G0 and G + 1: Increase in concentration to the extent that the history portion in the first cycle can be slightly discerned in the second cycle G + 1.5: G + 1 and G + 2 Intermediate G + 2: Concentration increase G + 2.5: Intermediate G + 3 between G + 2 and G + 3, so that the history portion in the first cycle is visually recognized in the second cycle G: Concentration increase G in the second cycle is severely increased in the second cycle -0.5: Intermediate G-1 between G0 and G-1: Density drop to the extent that the history part of the first cycle can be slightly discerned visually in the second cycle G-1.5: G-1 and G- Intermediate G-2 with 2: Density drop to the extent that the history part of the first cycle is visually recognized in the second cycle G-2.5: Intermediate G-3 between G-2 and G-3: First cycle History section severely decreased in the second cycle

<Example 2>
(Production of photoconductor)
A photoconductor 2 was prepared in the same manner as the photoconductor 1 except that the constituent materials and physical properties of the undercoat layer were changed as shown in Table 1.
The volume resistivity of the undercoat layer was adjusted by adjusting the film thickness.

(Ghost image evaluation)
Except that the photoconductor 2 was used and the pre-exposure intensity was changed as shown in Table 1, image formation was performed in the same manner as in Example 1, and ghost images were evaluated.

<Example 3>
(Production of photoconductor)
A photoconductor 3 was prepared in the same manner as the photoconductor 1 except that the constituent materials and physical properties of the undercoat layer were changed as shown in Table 1.

(Ghost image evaluation)
A ghost image was evaluated by performing image formation in the same manner as in Example 1 except that the photoconductor 3 was used and the pre-exposure intensity was changed as shown in Table 1.

<Example 4>
(Production of photoconductor)
A photoconductor 4 was prepared in the same manner as in Example 1 except that when the dispersion for forming the undercoat layer was prepared, the dispersion time by the sand mill was changed to 2 hours.

(Ghost image evaluation)
Using the photoconductor 4, image formation was performed in the same manner as in Example 1, and ghost images were evaluated.

<Example 5>
(Production of photoconductor)
A photoconductor 5 was prepared in the same manner as in Example 1 except that when the dispersion for forming the undercoat layer was prepared, the dispersion time by the sand mill was changed to 10 hours.

(Ghost image evaluation)
Using the photoreceptor 5, image formation was performed in the same manner as in Example 1, and ghost images were evaluated.

<Example 6>
(Ghost image evaluation)
Using the photoreceptor 1, image formation was performed in the same manner as in Example 1 except that the pre-exposure intensity before charging was changed to ² mJ / m ² , and ghost images were evaluated.

<Example 7>
(Ghost image evaluation)
Using the photoreceptor 1, image formation was performed in the same manner as in Example 1 except that the pre-exposure intensity before charging was changed to 11.0 mJ / m ² , and ghost images were evaluated.

<Comparative Example 1>
A ghost image was evaluated by performing image formation in the same manner as in Example 1 except that the photosensitive member 1 was used and exposure before charging was not performed.

<Comparative example 2>
In forming the undercoat layer of the photoconductor, a photoconductor was prepared in the same manner as in Example 1 except that no electron-accepting material was used, and an image was formed using this photoconductor to evaluate a ghost image.

<Comparative Example 3>
In forming the undercoat layer of the photoconductor, a photoconductor was prepared in the same manner as in Example 3 except that zinc oxide particles were not used, image formation was performed, and ghost images were evaluated.

  Table 1 shows a list of metal oxide particles, electron-accepting material, volume resistivity composition of the undercoat layer, pre-exposure strength, and ghost evaluation contained in the undercoat layer of the electrophotographic photosensitive member produced in this example and comparative example. It summarizes and shows.

DESCRIPTION OF SYMBOLS 1 Conductive support body, 2 Undercoat layer, 3 Photosensitive layer, 4 Intermediate layer, 5 Protective layer, 7 Electrophotographic photoreceptor, 31 Charge generation layer, 32 Charge transport layer, 200 Image forming apparatus, 208 Charging apparatus, 210 Exposure Device, 211 developing device, 212 transfer device, 213 cleaning device, 215 fixing device, 215 fixing device, 500 recording medium

Claims (5)

An electrophotographic photoreceptor having a conductive support, an undercoat layer disposed on the conductive support and containing a conductive metal oxide and an electron-accepting substance, and a photosensitive layer disposed on the undercoat layer; ,
Charging means for charging the surface of the electrophotographic photosensitive member;
Exposure means for exposing the surface of the charged electrophotographic photosensitive member to form an electrostatic latent image;
Developing means for containing a developer containing toner and developing the electrostatic latent image with the developer to form a toner image;
Transfer means for transferring the toner image formed on the surface of the electrophotographic photosensitive member to a recording medium,
Image formation in which the entire surface of the electrophotographic photosensitive member is exposed by the exposure unit before the surface of the electrophotographic photosensitive member is charged by the charging unit when the image formation is resumed after the image formation is temporarily stopped. apparatus. The image forming apparatus according to claim 1, wherein a volume resistivity of the undercoat layer of the electrophotographic photosensitive member is in a range of 10 ⁸ Ωcm to 10 ¹¹ Ωcm.   The image forming apparatus according to claim 1, wherein the charging unit includes a charging member to which only a direct-current voltage is applied and is charged in contact with the surface of the electrophotographic photosensitive member. 4. The image forming apparatus according to claim 1, wherein the exposure unit performs the overall exposure on the surface of the electrophotographic photosensitive member at 3 mJ / m ² or more. 5. An electrophotographic photosensitive member having a conductive support, an undercoat layer disposed on the conductive support and including a conductive metal oxide and an electron-accepting substance, and a photosensitive layer disposed on the undercoat layer A charging process for charging the surface;
An electrostatic latent image forming step of exposing the surface of the charged electrophotographic photosensitive member to form an electrostatic latent image; and
Developing the electrostatic latent image with a developer containing toner to form a toner image;
A transfer step of transferring a toner image formed on the surface of the electrophotographic photoreceptor to a recording medium;
A pre-exposure step of exposing the entire surface of the electrophotographic photosensitive member by an exposure unit that forms the electrostatic latent image before the charging step when the image formation is resumed after the image formation is temporarily stopped;
An image forming method comprising: