JP2013200421A - Image formation device and process cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image formation device capable of obtaining an image that suppresses an occurence of an afterimage phenomenon (ghost image) generated by a remaining history of a previous image.SOLUTION: The image formation device comprises: a photoreceptor 10 that satisfies an expression (1):(▵V/20)-1≤▵C≤(▵V/20)+1 and an expression (2):▵V≥30; a charging device 20 (one example of charging means); an exposure device 30 (one example of exposure means); a development device 40 (one example of development means); a transfer device 50 (one example of transfer means); and a discharging device 80 (one example of discharging means), in which a time to charge after discharged is equal to 100 msec or less. In the expressions (1) and (2), ▵V represents a difference (absolute value) between surface potential (V) of an unexposed part of the photoreceptor 10 when a time Tc (msec) up to charging after discharged elapses and surface potential (V) of an unexposed part of the photoreceptor 10 when a time Td (msec) up to charging after discharged elapses, and ▵C indicates a reduction rate (%) of an electrostatic capacitance of the photoreceptor 10 by transferring.

Description

  The present invention relates to an image forming apparatus.

  In recent years, so-called electrophotographic (xerographic) image forming apparatuses having an electrophotographic photosensitive member, a charging unit, an exposure unit, a developing unit, a transfer unit, and a charge eliminating unit are known.

For example, an image forming apparatus that uses a photoconductor having a protective layer with high mechanical strength and appropriately controls the time from the start of static elimination to the end of charging between the film thickness and relative dielectric constant of the surface protective layer (for example, , See Patent Document 1).
In addition, for example, an image forming apparatus (see, for example, Patent Documents 2 to 3) in which the photoreceptor surface potential after transfer in a non-writing portion is 100 V or less as an absolute value has been proposed.
Further, for example, Formula (1) [Time between charge removal and charging (seconds) = P / S: where P is the electrostatic latent image carrier surface facing the center of the charge removal means and the static electricity corresponding to the charger center. This represents the circumference (mm) of the surface of the electrostatic latent image carrier. An image forming apparatus (for example, see Patent Document 4) in which the time between charge removal and charging represented by S is a system linear velocity (mm / second) is 0.15 seconds or less has been proposed.

JP 2008-299039 A JP 2006-251671 A JP 2006-337911 A JP 2005-208594 A

  An object of the present invention is to provide an image forming apparatus capable of obtaining an afterimage phenomenon (hereinafter referred to as “ghost”) caused by the history of the previous image remaining and an image in which occurrence of density unevenness is suppressed.

The above problem is solved by the following means. That is,
The invention according to claim 1
An electrophotographic photoreceptor satisfying the following formulas (1) and (2);
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 formed on the electrophotographic photosensitive member into a toner image by the developer;
Transfer means for transferring the toner image to a transfer object;
After the toner image is transferred to the transfer medium, before the surface of the electrophotographic photosensitive member is charged, the surface of the electrophotographic photosensitive member is irradiated with a neutralizing light to remove static electricity;
With
An image forming apparatus in which the time until the surface of the electrophotographic photosensitive member is charged after being charged is 100 msec or less.

Formula (1): (ΔV / 20) −1 ≦ ΔC ≦ (ΔV / 20) +1
Formula (2): ΔV ≧ 30
(In Formula (1) and Formula (2), ΔV represents an unexposed portion of the electrophotographic photosensitive member when a time Tc (msec) until charging after the surface of the electrophotographic photosensitive member has been neutralized has elapsed. And the surface potential (V) of the unexposed portion of the electrophotographic photosensitive member when the time Td (msec) until development after the surface of the electrophotographic photosensitive member has been neutralized, (ΔC represents a reduction rate (%) of the electrostatic capacity of the unexposed portion of the electrophotographic photosensitive member due to the transfer of the toner image.)

The invention according to claim 2
An electrophotographic photoreceptor satisfying the following formulas (1) and (2);
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 formed on the electrophotographic photosensitive member into a toner image by the developer;
Transfer means for transferring the toner image to a transfer object;
After the toner image is transferred to the transfer medium, before the surface of the electrophotographic photosensitive member is charged, the surface of the electrophotographic photosensitive member is irradiated with a neutralizing light to remove static electricity;
With
The time until the surface of the electrophotographic photosensitive member is neutralized and charged is 100 msec or less,
A process cartridge attached to and detached from the image forming apparatus.

Formula (1): (ΔV / 20) −1 ≦ ΔC ≦ (ΔV / 20) +1
Formula (2): ΔV ≧ 30
(In Formula (1) and Formula (2), ΔV represents an unexposed portion of the electrophotographic photosensitive member when a time Tc (msec) until charging after the surface of the electrophotographic photosensitive member has been neutralized has elapsed. And the surface potential (V) of the unexposed portion of the electrophotographic photosensitive member when the time Td (msec) until development after the surface of the electrophotographic photosensitive member has been neutralized, (ΔC represents a reduction rate (%) of the electrostatic capacity of the unexposed portion of the electrophotographic photosensitive member due to the transfer of the toner image.)

According to the first aspect of the present invention, an image can be obtained in which an image in which the occurrence of ghost and density unevenness is suppressed is obtained as compared with the case where no electrophotographic photosensitive member satisfying the relationship of the above formulas (1) and (2) is provided. Equipment can be provided.
According to the second aspect of the invention, a process cartridge capable of obtaining an image in which the occurrence of ghost and density unevenness is suppressed as compared with the case where no electrophotographic photosensitive member satisfying the relationship of the above formulas (1) and (2) is provided. Can provide.

1 is a schematic partial cross-sectional view showing an electrophotographic photosensitive member according to the present embodiment. It is a general | schematic fragmentary sectional view which shows the electrophotographic photoreceptor which concerns on other this embodiment. It is a general | schematic fragmentary sectional view which shows the electrophotographic photoreceptor which concerns on other this embodiment. 1 is a schematic configuration diagram illustrating an image forming apparatus according to an exemplary embodiment. It is a schematic block diagram which shows the image forming apparatus which concerns on other this embodiment.

  Embodiments that are examples of the present invention will be described below.

The image forming apparatus according to the present embodiment includes an electrophotographic photosensitive member, a charging unit that charges the surface of the electrophotographic photosensitive member, and an exposure unit that exposes the surface of the charged electrophotographic photosensitive member to form an electrostatic latent image. And developing means for containing a developer containing toner, and developing the electrostatic latent image formed on the electrophotographic photosensitive member into a toner image by the developer, and a transfer means for transferring the toner image to the transfer target. An image forming apparatus comprising: a charge removing unit that discharges the surface of the electrophotographic photosensitive member with a discharge light after the toner image is transferred to the transfer medium and before the surface of the electrophotographic photosensitive member is charged. Device.
Then, an electrophotographic photoreceptor satisfying the following formulas (1) and (2) is applied as the electrophotographic photoreceptor.

Formula (1): (ΔV / 20) −1 ≦ ΔC ≦ (ΔV / 20) +1
Formula (2): ΔV ≧ 30
In the formulas (1) and (2), ΔV represents the surface of the unexposed portion of the electrophotographic photosensitive member when the time Tc (msec) until charging after the surface of the electrophotographic photosensitive member has been neutralized has elapsed. The difference between the potential (V) and the surface potential (V) of the unexposed portion of the electrophotographic photosensitive member when the time Td (msec) until the development after the surface of the electrophotographic photosensitive member has been neutralized has elapsed ( Absolute value).
ΔC represents a reduction rate (%) of the electrostatic capacity of the unexposed portion of the electrophotographic photosensitive member due to the transfer of the toner image.

Note that various conditions (transfer voltage, intensity of static elimination light, time Tc (msec), time Td (msec), etc.) for obtaining ΔV and ΔC are determined by the configuration of the target image forming apparatus.
In addition, in the case of the direct transfer method in which the toner image formed on the electrophotographic photosensitive member is directly transferred to a transfer material such as a recording paper, the capacitance reduction rate ΔC (%) The rate at which the electrostatic capacity of the electrophotographic photosensitive member decreases due to the voltage applied when transferring to a transfer medium such as the above.
On the other hand, the decrease rate ΔC (%) of the electrostatic capacity is in the case of the intermediate transfer method in which the toner image formed on the electrophotographic photosensitive member is transferred to the intermediate transfer member and then transferred to the transfer member such as recording paper. The ratio at which the electrostatic capacity of the electrophotographic photosensitive member is reduced by the voltage applied when the toner image is transferred to the intermediate transfer member is shown.

In the image forming apparatus according to the present embodiment, an image in which the occurrence of ghost and density unevenness is suppressed can be obtained by applying the electrophotographic photosensitive member satisfying the expressions (1) and (2).
Although this reason is not certain, it is thought to be due to the following reasons.

  In recent years, with the increase in the speed of image forming apparatuses, the time from neutralization to charging (time Tc from the surface of the electrophotographic photosensitive member to charging after being neutralized) has become shorter. In particular, in an image forming apparatus that has been speeded up to 100 msec or less from static elimination to charging, the time from static elimination to charging is shortened, so that the surface potential of the surface of the electrophotographic photosensitive member is sufficiently removed. Charging is performed, and a ghost (an afterimage phenomenon caused by the history of the previous image remaining) may occur.

As described above, it is considered that the following phenomenon occurs as a mechanism for generating a ghost in high-speed image formation in which the time from static elimination to charging is short.
First, when the time from static elimination to charging is short, in the unexposed area (non-image area) of the previous cycle, the carrier generated in the photosensitive layer (for example, the charge generation layer) by static elimination is charged before the charging is completed. It is considered that the surface potential of the electrophotographic photosensitive member is lowered after the end of charging without reaching the surface of the photosensitive member.
On the other hand, in the exposed portion (image portion) of the previous cycle, the surface potential of the electrophotographic photosensitive member has already decreased due to exposure, and the number of carriers generated in the photosensitive layer (for example, the charge generation layer) due to charge removal is reduced to the unexposed portion (non-exposed portion). Therefore, it is considered that the decrease in the surface potential of the electrophotographic photosensitive member after the completion of charging is small.
Therefore, the surface potential of the exposed portion (image portion) in the previous cycle is higher than that of the unexposed portion (non-image portion), and it is considered that when developing in such a state, the image density is lowered and ghost is generated. .
In addition, the generation of ghost is suppressed as ΔV <30 as the charge transport layer of the photoconductor is thinned. However, when the charge transport layer is thin, the electrophotographic photoconductor is charged. May not be obtained, and density unevenness may occur.

In contrast, when an electrophotographic photosensitive member satisfying the formulas (1) and (2) is applied, the occurrence of ghost and density unevenness is suppressed in an image forming apparatus that has been speeded up to 100 msec or less from static elimination to charging. I think that.
Specifically, by adjusting the film thickness of the charge transport layer of the photoreceptor, the chargeability of the photoreceptor is ensured and density unevenness is suppressed.
By adjusting the film thickness of the charge transport layer, the formula (2) is satisfied, and in the unexposed part (non-image part) of the previous cycle, carriers generated in the photosensitive layer (for example, the charge generation layer) by charge removal are charged. By completing the charging, the surface potential of the electrophotographic photosensitive member is decreased after the charging is completed, so that the charged potential of the unexposed portion is reduced compared to the exposed portion. The developability of the toner increases.
Therefore, by satisfying equation (1), the electrostatic capacity of the electrophotographic photosensitive member is reduced by transfer, and the developability in the unexposed portion (non-image portion) of the previous cycle of the electrophotographic photosensitive member is actively reduced. Let A ghost is suppressed by offsetting the developability decrease due to the decrease in capacitance with the increase in developability due to the decrease in charging potential.

  For this reason, it is considered that the image forming apparatus according to the present embodiment can obtain an image in which the occurrence of ghost and density unevenness is suppressed.

Here, the electrophotographic photosensitive member satisfies the above formula (1), preferably the following (1-2), more preferably the following formula (1-3).
Further, the electrophotographic photoreceptor satisfies the above formula (2), preferably the following (2-2), more preferably the following formula (2-3).
Formula (1-2): (ΔV / 20) −0.7 ≦ ΔC ≦ (ΔV / 20) +0.7
Formula (1-3): (ΔV / 20) −0.3 ≦ ΔC ≦ (ΔV / 20) +0.3
Formula (2-2): 70 ≧ ΔV ≧ 30
Formula (2-3): 50 ≧ ΔV ≧ 30

In order for the electrophotographic photoreceptor to satisfy the formula (1), for example, as an electrophotographic photoreceptor, a conductive substrate, a photosensitive layer provided on the conductive substrate, and a protective layer provided on the photosensitive layer, And a protective layer is a cured film of a composition comprising a reactive charge transport material and, if necessary, other reactive substances (for example, guanamine compound, melamine compound, etc.) It is preferable to apply an electrophotographic photoreceptor composed of a cured film in which unreacted groups such as reactive charge transporting materials and other reactive substances remain. As a result, charges (carriers) are easily accumulated in the protective layer due to unreacted groups in the protective layer, and the accumulated charges are released by the transfer, and as a result, the unexposed portion ( It is considered that the electrostatic capacity of the non-image portion is likely to decrease. This is because, at the time of transfer, an unexposed portion (non-image portion) where no toner is placed has a higher transfer voltage load than an exposed portion (image portion) where toner is placed, and charges accumulated in the protective layer are released. This is because the capacitance is likely to be reduced.
In order to actively leave unreacted groups such as the reactive charge transporting material in the protective layer, it is possible to adjust the curing time (for example, heating / drying time) of the composition containing the reactive charge transporting material. Good.

  In order for the electrophotographic photoreceptor to satisfy the formula (2), it is preferable to adjust the thickness of the photosensitive layer (particularly, the charge transport layer) (for example, the thickness of the photosensitive layer or the charge transport layer of 20 μm to 40 μm).

  In the formulas (1) and (2), ΔV and ΔC are values measured by “measurement of ΔV of the photoconductor” and “measurement of ΔC of the photoconductor” described later.

  Hereinafter, an image forming apparatus according to the present embodiment will be described in detail with reference to the drawings.

FIG. 4 is a schematic configuration diagram illustrating the image forming apparatus according to the present embodiment.
As shown in FIG. 4, the image forming apparatus 101 according to the present embodiment includes, for example, an electrophotographic photosensitive member 10 that rotates clockwise as indicated by an arrow A, and an electronic A charging device 20 (an example of a charging unit) that is provided relative to the photographic photosensitive member 10 and charges the surface of the electrophotographic photosensitive member 10, and the surface of the electrophotographic photosensitive member 10 charged by the charging device 20 is exposed to light. An exposure device 30 (an example of an exposure unit) that forms an electrostatic latent image, and a toner contained in a developer is attached to the electrostatic latent image formed by the exposure device 30 to form a toner image on the surface of the electrophotographic photoreceptor 10. A developing device 40 (an example of a developing unit) that forms the toner image, and the recording paper P (transfer medium) is charged to a polarity different from the charging polarity of the toner, and the toner image on the electrophotographic photoreceptor 10 is transferred to the recording paper P Transfer device 50 and electrons After the toner image is transferred onto the recording paper P by the cleaning device 70 (an example of a toner removing unit) that cleans the surface of the true photoconductor 10 and the transfer device 50, the surface of the electrophotographic photoconductor 10 is charged by the charging device 20. Before being performed, the surface of the electrophotographic photosensitive member 10 is provided with a static eliminator 80 (an example of a static eliminator) that neutralizes the surface by irradiating the surface with a static elimination light. A fixing device 60 is provided for fixing the toner image while conveying the recording paper P on which the toner image is formed.

  Details of main components in the image forming apparatus 101 according to the present embodiment will be described below.

[Electrophotographic photoreceptor]
1 to 3 schematically show a cross section of a part of an electrophotographic photoreceptor 10 according to the present embodiment.
The electrophotographic photosensitive member 10 shown in FIG. 1 is provided with an undercoat layer 1 on a conductive support 4, a charge generation layer 2 and a charge transport layer 3 are provided on the undercoat layer as photosensitive layers, and further, A surface protective layer 5 serving as a surface layer is provided.
The electrophotographic photoreceptor 10 shown in FIG. 2 includes a photosensitive layer having functions separated into a charge generation layer 2 and a charge transport layer 3 as in the electrophotographic photoreceptor 10 shown in FIG. A charge transport layer 3, a charge generation layer 2, and a surface protective layer 5 are sequentially provided on 1.
An electrophotographic photoreceptor 10 shown in FIG. 3 contains a charge generation material and a charge transport material in the same layer, that is, a single-layer type photosensitive layer 6 (charge generation / charge transport layer). A surface protective layer 5 is provided.

  The electrophotographic photoreceptor 10 shown in FIGS. 1 to 3 shows a form in which the surface protective layer 5 is provided on the photosensitive layer and the surface protective layer 5 is used as the outermost surface layer. When not provided, the uppermost layer of the photosensitive layer becomes the outermost surface layer. Specifically, in the case of the layer structure of the electrophotographic photoreceptor 10 shown in FIG. 1 and the layer structure in which the surface protective layer 5 is not provided, the charge transport layer 3 corresponds to the outermost surface layer. Further, in the case of the layer configuration of the electrophotographic photoreceptor 10 shown in FIG. 3 in which the surface protective layer 5 is not provided, the single-layer type photosensitive layer 6 corresponds to the outermost surface layer.

  Hereinafter, each element will be described based on the electrophotographic photoreceptor 10 shown in the drawing as a representative example. Note that the reference numerals are omitted.

  Hereinafter, each element of the electrophotographic photoreceptor 10 will be described. Note that the reference numerals are omitted.

(Conductive substrate)
Any conductive substrate may be used as long as it is conventionally used. For example, thin films (eg, metals such as aluminum, nickel, chromium, stainless steel, and films of aluminum, titanium, nickel, chromium, stainless steel, gold, vanadium, tin oxide, indium oxide, indium tin oxide (ITO), etc.) And a plastic film coated or impregnated with a conductivity-imparting agent, a plastic film coated or impregnated with a conductivity-imparting agent, and the like. The shape of the substrate is not limited to a cylindrical shape, and may be a sheet shape or a plate shape.

  When a metal pipe is used as the conductive substrate, the surface may be left as it is, and processing such as mirror cutting, etching, anodic oxidation, rough cutting, centerless grinding, sand blasting, wet honing has been performed in advance. Also good.

(Undercoat layer)
The undercoat layer includes, for example, a binder resin, metal oxide particles, an electron accepting compound, and, if necessary, other additives.

Examples of the binder resin include known resins. For example, known polymer resin compounds (for example, acetal resins such as polyvinyl butyral, polyvinyl alcohol resins, caseins, polyamide resins, cellulose resins, gelatin, polyurethane resins, polyesters) Resins, methacrylic resins, acrylic resins, polyvinyl chloride resins, polyvinyl acetate resins, vinyl chloride-vinyl acetate-maleic anhydride resins, silicone resins, silicone-alkyd resins, phenol resins, phenol-formaldehyde resins, melamine resins, urethane resins, etc. ), A charge transporting resin having a charge transporting group, a conductive resin (for example, polyaniline) and the like.
Among these, as the binder resin, a resin insoluble in the coating solvent for the upper layer (charge generation layer) is desirable, and phenol resin, phenol-formaldehyde resin, melamine resin, urethane resin, epoxy resin, and the like are particularly preferable.

Examples of the metal oxide particles include metal oxide particles having a powder resistance (volume resistivity) of 10 ² Ω · cm to 10 ¹¹ Ω · cm, specifically, for example, tin oxide and titanium oxide. Zinc oxide, zirconium oxide and the like.
Among these, zinc oxide is suitable as the metal oxide particles.

  The metal oxide particles may be subjected to a surface treatment, or may be a mixture of two or more types having different surface treatment types or particles having different particle diameters.

The volume average particle diameter of the metal oxide particles is desirably 50 nm or more and 500 nm or less (preferably 60 or more and 1000 or less).
The specific surface area (specific surface area by BET method) of the metal oxide particles is desirably 10 m ² / g or more.

  For example, the content of the metal oxide particles is preferably 10% by mass or more and 80% by mass or less, and more preferably 40% by mass or more and 80% by mass or less with respect to the binder resin.

Examples of the electron-accepting compound include quinone compounds (for example, chloranil and bromoanil), tetracyanoquinodimethane compounds, and fluorenone compounds (for example, 2,4,7-trinitrofluorenone, 2,4,5,7- Tetranitro-9-fluorenone, etc.), oxadiazole compounds (for example, 2- (4-biphenyl) -5- (4-t-butylphenyl) -1,3,4-oxadiazole and 2,5-bis ( 4-naphthyl) -1,3,4-oxadiazole, 2,5-bis (4-diethylaminophenyl) 1,3,4-oxadiazole, etc.), xanthone compounds, thiophene compounds, diphenoquinone compounds (eg 3 , 3 ′, 5,5 ′ tetra-t-butyldiphenoquinone) and the like, and the like. Good compound having the.
Preferred examples of the compound having an anthraquinone structure include acceptor compounds having an anthraquinone structure, such as hydroxyanthraquinone compounds, aminoanthraquinone compounds, and aminohydroxyanthraquinone compounds. Specifically, examples include anthraquinone and alizarin. Quinizarin, antralphine, pull pudding and the like.

  The electron-accepting compound may be contained in the undercoat layer in a state of being dispersed separately from the metal oxide particles, but is contained in the undercoat layer in a state of being attached to the surface of the metal oxide particles. Also good.

Examples of the method for attaching the electron accepting compound to the surface of the metal oxide particles include a dry method and a wet method.
The dry method is, for example, by dropping an acceptor compound dissolved directly or in an organic solvent while spraying together with dry air or nitrogen gas, while applying shear force to the metal oxide particles by stirring or the like, In this method, the electron-accepting compound is attached to the surface of the metal oxide particles. When dripping or spraying, it is desirable to carry out at the temperature below the boiling point of a solvent, for example. After dripping or spraying, baking may be performed at 100 ° C. or higher.
On the other hand, in the wet method, for example, the electron-accepting compound is added and the solvent is removed by dispersing the metal oxide particles in the solvent by stirring, ultrasonic waves, sand mill, attritor, ball mill, etc. This is a method of attaching a compound to the surface of metal oxide particles. The solvent removal method is performed, for example, by filtration or distillation. After removing the solvent, baking may be performed at 100 ° C. or higher.

  The content of the electron-accepting compound is, for example, preferably from 0.01% by mass to 20% by mass with respect to the metal oxide particles.

Other additives include, for example, electron transporting pigments (for example, polycyclic condensation systems, azo systems), zirconium chelate compounds, titanium chelate compounds, aluminum chelate compounds, titanium alkoxide compounds, organic titanium compounds, silane coupling agents, and the like. Known materials are used. In particular, the silane coupling agent is used for the surface treatment of the metal oxide particles, but may be further added to the undercoat layer as an additive.
Specific examples of the silane coupling agent include, for example, vinyltrimethoxysilane, γ-methacryloxypropyl-tris (β-methoxyethoxy) silane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycol. Sidoxypropyltrimethoxysilane, 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.
Specific 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, zirconium octoate. , Zirconium naphthenate, zirconium laurate, zirconium stearate, zirconium isostearate, methacrylate zirconium butoxide, stearate zirconium butoxide, isostearate zirconium butoxide and the like.

In forming the undercoat layer, a coating solution for forming an undercoat layer in which the above components are added to a solvent is used.
In addition, as a method for dispersing particles in the coating solution for forming the undercoat layer, a media disperser such as a ball mill, a vibrating ball mill, an attritor, a sand mill, a horizontal sand mill, an agitator, an ultrasonic disperser, a roll mill, a high-pressure homogenizer, etc. Medialess dispersers are used. Here, examples of the high-pressure homogenizer include a collision method in which the dispersion liquid is dispersed by liquid-liquid collision or liquid-wall collision in a high-pressure state, and a penetration method in which a fine flow path is dispersed in a high-pressure state. .

  Examples of the method for applying the coating liquid for forming the undercoat layer onto the conductive substrate include dip coating, push-up coating, wire bar coating, spray coating, blade coating, knife coating, and curtain coating. It is done.

  The thickness of the undercoat layer is desirably 15 μm or more, more desirably 15 μm to 50 μm, and further desirably 20 μm to 50 μm.

  Here, although not shown, an intermediate layer may be further provided between the undercoat layer and the photosensitive layer. As the binder resin used for the intermediate layer, acetal resins 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 In addition to polymer resins such as acetate resin, vinyl chloride-vinyl acetate-maleic anhydride resin, silicone resin, silicone-alkyd resin, phenol-formaldehyde resin, melamine resin, zirconium, titanium, aluminum, manganese, silicon atom, etc. An organometallic compound containing These compounds may be used alone or as a mixture or polycondensate of a plurality of compounds. Among them, an organometallic compound containing zirconium or silicon is preferable in that it has a low residual potential, a small potential change due to the environment, and a small potential change due to repeated use.

In forming the intermediate layer, a coating solution for forming an intermediate layer in which the above components are added to a solvent is used.
As the coating method for forming the intermediate layer, usual methods such as a dip coating method, a push-up coating method, a wire bar coating method, a spray coating method, a blade coating method, a knife coating method, and a curtain coating method are used.

  In addition to improving the coatability of the upper layer, the intermediate layer also serves as an electrical blocking layer. However, if the film thickness is too large, the electrical barrier becomes too strong and the potential increases due to desensitization or repetition. May cause. Therefore, when forming the intermediate layer, it is preferable to set the film thickness within the range of 0.1 μm to 3 μm. In this case, the intermediate layer may be used as the undercoat layer.

(Charge generation layer)
The charge generation layer includes, for example, a binder resin and a charge generation material.

Examples of the charge generation material include known charge generation materials such as organic pigments and inorganic faces.
Examples of the organic pigment include azo pigments (for example, bisazo and trisazo), fused aromatic pigments (for example, dibromoanthanthrone), perylene pigments, pyrrolopyrrole pigments, and phthalocyanine pigments.
Examples of the inorganic pigment include trigonal selenium and zinc oxide.

As the charge generation material, in particular, an inorganic pigment is preferable when an exposure wavelength of 380 nm to 500 nm is used, and a metal and a metal-free phthalocyanine pigment are preferable when an exposure wavelength of 700 nm to 800 nm is used.
Examples of the phthalocyanine pigment include hydroxygallium phthalocyanine disclosed in JP-A-5-263007 and JP-A-5-279591, chlorogallium phthalocyanine disclosed in JP-A-5-98181, and JP-A-5-140472 and JP-A-5-140473. Particularly preferred are dichlorotin phthalocyanine prepared, and titanyl phthalocyanine disclosed in JP-A-4-189873 and JP-A-5-43813.

Examples of the binder resin include polycarbonate resin such as bisphenol A type or bisphenol Z type, acrylic resin, methacrylic resin, polyarylate resin, polyester resin, polyvinyl chloride resin, polystyrene resin, acrylonitrile-styrene copolymer resin, acrylonitrile. -Butadiene copolymer, polyvinyl acetate resin, polyvinyl formal resin, polysulfone resin, styrene-butadiene copolymer resin, vinylidene chloride-acrylonitrile copolymer resin, vinyl chloride-vinyl acetate-maleic anhydride resin, silicone resin, phenol -Formaldehyde resin, polyacrylamide resin, polyamide resin, poly-N-vinylcarbazole resin, etc. are mentioned. These binder resins may be used alone or in combination of two or more.
The mixing ratio (mass ratio) of the charge generation material and the binder resin is preferably in the range of 10: 1 to 1:10, for example.

  When forming the charge generation layer, a coating solution for forming a charge generation layer in which the above components are added to a solvent is used.

  As a method for dispersing particles (for example, charge generation material) in the coating solution for forming the charge generation layer, a media dispersion machine such as a ball mill, a vibration ball mill, an attritor, a sand mill, a horizontal sand mill, an agitation, an ultrasonic dispersion machine, a roll mill, etc. Medialess dispersers such as high-pressure homogenizers are used. Examples of the high-pressure homogenizer include a collision method in which the dispersion liquid is dispersed by liquid-liquid collision or liquid-wall collision in a high-pressure state, and a penetration method in which a fine flow path is dispersed in a high-pressure state.

  Examples of the method for applying the charge generation layer forming coating liquid on the undercoat layer include dip coating, push-up coating, wire bar coating, spray coating, blade coating, knife coating, and curtain coating. It is done.

  The thickness of the charge generation layer is desirably set in the range of 0.01 μm to 5 μm, more desirably 0.05 μm to 2.0 μm.

(Charge transport layer)
The charge transport layer includes, for example, a charge transport material and a binder resin.
The charge transport layer may be configured to include, for example, a polymer charge transport material.

Examples of the charge transport material include known materials such as an electron transport compound and a hole transport compound.
Examples of the electron transporting compound include quinone compounds (eg, p-benzoquinone, chloranil, bromanyl, anthraquinone, etc.), tetracyanoquinodimethane compounds, fluorenone compounds (eg, 2,4,7-trinitrofluorenone, etc.). , Xanthone compounds, benzophenone compounds, cyanovinyl compounds, ethylene compounds and the like.
Examples of the hole transporting compound include triarylamine compounds, benzidine compounds, arylalkane compounds, aryl-substituted ethylene compounds, stilbene compounds, anthracene compounds, hydrazone compounds, and the like.
These charge transport materials may be used alone or in combination of two or more.

  As the charge transport material, the following structure is particularly preferable from the viewpoint of mobility.

In Structural Formula (B-1), R ^B1 represents a hydrogen atom or a methyl group, and n ′ represents 1 or 2. Ar ^B1 and Ar ^B2 represent a substituted or unsubstituted aryl group, and the substituent includes a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or a carbon number Represents a substituted amino group substituted with 1 to 3 alkyl groups.

In the structural formula (B-2), R ^B2 and R ^{B2 ′} each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms. R ^B3 , R ^{B3 ′} , R ^B4 , and R ^{B4 ′} each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or 1 to 2 carbon atoms. Represents an amino group substituted with an alkyl group, a substituted or unsubstituted aryl group, or —C (R ^B5 ) ═C (R ^B6 ) (R ^B7 ), and R ^B5 , R ^B6 , and R ^B7 represent a hydrogen atom Represents a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group. M ′ and n ″ are integers of 0 or more and 2 or less.

In Structural Formula (B-3), R ^B8 represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, a substituted or unsubstituted aryl group, or —CH═CH— CH = C (Ar ^B3 ) ₂ is represented. Ar ^B3 represents a substituted or unsubstituted aryl group. R ^B9 and R ^B10 are each independently an amino group substituted with a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or an alkyl group having 1 to 2 carbon atoms. Represents a group, a substituted or unsubstituted aryl group.

Examples of the binder resin include 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. Polymer, 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 Is mentioned. Examples of the binder resin include polyester polymer charge transport materials disclosed in JP-A-8-176293 and JP-A-8-208820. These binder resins may be used alone or in combination of two or more.
The mixing ratio (weight ratio) between the charge transport material and the binder resin is preferably 10: 1 to 1: 5, for example.

Examples of the polymer charge transporting material include known materials having charge transporting properties such as poly-N-vinylcarbazole and polysilane.
In particular, as the polymer charge transport material, for example, the polyester-based polymer charge transport material disclosed in JP-A-8-176293 and JP-A-8-208820 has a high charge transport property, Especially desirable. The polymer charge transport material may constitute a charge transport layer alone, or may be mixed with a binder resin to constitute a charge transport layer.

The charge transport layer is formed using a charge transport layer forming coating solution in which the above components are added to a solvent.
Etc.

  Examples of methods for applying the charge transport layer forming coating solution onto the charge generation layer include dip coating, push-up coating, wire bar coating, spray coating, blade coating, knife coating, and curtain coating. The usual method is used.

  The film thickness of the charge transport layer is desirably set in the range of 5 μm to 50 μm, more desirably 10 μm to 40 μm, and even more desirably 10 μm to 30 μm.

(Protective layer)
The protective layer is composed of, for example, a cured film of a composition containing a reactive charge transport material. That is, the protective layer is composed of a charge transporting cured film containing a polymer (or a crosslinked product) of a reactive charge transport material.

  Further, the protective layer is composed of a cured film of a composition containing at least one selected from a guanamine compound and a melamine compound from the viewpoint of improving mechanical strength and extending the life of the electrophotographic photosensitive member. Also good. That is, the protective layer may be composed of a charge transporting cured film including a reactive charge transporting material and a polymer (crosslinked product) of at least one selected from a guanamine compound and a melamine compound.

The reactive charge transport material will be described.
Examples of the reactive charge transporting material include reactive charge transporting materials having —OH, —OCH ₃ , —NH ₂ , —SH, —COOH, etc.) as reactive functional groups.

  The reactive charge transport material is preferably a charge transport material having at least two (or three) reactive functional groups. As described above, the increase of the reactive functional group in the charge transporting material increases the crosslink density and makes it easier to obtain a cured film (crosslinked film) with higher strength.

The reactive charge transport material is preferably a compound represented by the following general formula (I) from the viewpoint of suppressing wear of the foreign matter removing member and suppressing wear of the electrophotographic photosensitive member.
^{F - ((- R 13 -X} ) n1 (R 14) n2 -Y) n3 (I)
In general formula (I), F is an organic group (charge transport skeleton) derived from a compound having charge transporting ability, and R ¹³ and R ¹⁴ are each independently a straight chain or branched chain having 1 to 5 carbon atoms. N1 represents 0 or 1, n2 represents 0 or 1, and n3 represents an integer of 1 or more and 4 or less. X represents an oxygen, NH, or sulfur atom, and Y represents a reactive functional group.

  In general formula (I), an arylamine derivative is preferably used as the compound having charge transport ability in an organic group derived from a compound having charge transport ability, which represents F. Preferred examples of the arylamine derivative include a triphenylamine derivative and a tetraphenylbenzidine derivative.

  The compound represented by the general formula (I) is preferably a compound represented by the following general formula (II). The compound represented by the general formula (II) is particularly excellent in charge mobility, stability against oxidation and the like.

In general formula (II), Ar ¹ to Ar ⁴ may be the same or different and each independently represents a substituted or unsubstituted aryl group, and Ar ⁵ represents a substituted or unsubstituted aryl group or a substituted or unsubstituted group. D represents — (— R ¹³ —X) _n1 (R ¹⁴ ) _n2 —Y, c represents 0 or 1 independently, k represents 0 or 1, and the total number of D is 1 or more and 4 or less. R ¹³ and R ¹⁴ each independently represents a linear or branched alkylene group having 1 to 5 carbon atoms, n1 represents 0 or 1, n2 represents 0 or 1, and X represents oxygen. , NH, or a sulfur atom, and Y represents a reactive functional group.
Here, as a substituent in the substituted aryl group and the substituted arylene group, other than D, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a substituted or unsubstituted group having 6 to 10 carbon atoms And aryl groups.

In the general formula (II), “— (— R ¹³ —X) _n1 (R ¹⁴ ) _n2 —Y” representing D is the same as in the general formula (I), and R ¹³ and R ¹⁴ are each independently carbon. A linear or branched alkylene group having a number of 1 or more and 5 or less. N1 is preferably 1. N2 is preferably 1. X is preferably oxygen.

The total number of D in the general formula (II) corresponds to n3 in the general formula (I), preferably 2 or more and 4 or less, more preferably 3 or more and 4 or less.
Further, in the general formula (I) or general formula (II), when the total number of D is 2 or more and 4 or less, preferably 3 or more and 4 or less in one molecule, the crosslinking density is increased and a crosslinked film having higher strength is obtained. In particular, the rotational torque of the electrophotographic photosensitive member when using a blade member for removing foreign matter is reduced, and the wear of the blade member and the wear of the electrophotographic photosensitive member are suppressed. Although details of this are unknown, as described above, by increasing the number of reactive functional groups, a cured film having a high crosslinking density is obtained, and molecular motion on the extreme surface of the electrophotographic photosensitive member is suppressed, so that the blade member This is presumed to be due to weakening of interaction with surface molecules.

In general formula (II), Ar ₁ to Ar ₄ are preferably any one of the following formulas (1) to (7). The following formulas (1) to (7) are shown together with “— (D) _C ” which can be connected to each Ar ₁ to Ar ₄ .

In formulas (1) to (7), R ¹⁵ is phenyl substituted with a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms. Represents a group selected from the group consisting of a group, an unsubstituted phenyl group, and an aralkyl group having 7 to 10 carbon atoms, wherein R ¹⁶ to R ¹⁸ are each a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, and a carbon number One selected from the group consisting of an alkoxy group having 1 to 4 carbon atoms, a phenyl group substituted with an alkoxy group having 1 to 4 carbon atoms, an unsubstituted phenyl group, an aralkyl group having 7 to 10 carbon atoms, and a halogen atom Ar represents a substituted or unsubstituted arylene group, D and c are the same as “D” and “c” in formula (II), s represents 0 or 1, and t is 1 or more, respectively. 3 or less A representative.
Here, as Ar in Formula (7), what is represented by following formula (8) or (9) is desirable.

In formulas (8) to (9), R ¹⁹ and R ²⁰ are each a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms. This represents one selected from the group consisting of a substituted phenyl group, an unsubstituted phenyl group, an aralkyl group having 7 to 10 carbon atoms, and a halogen atom, and t represents an integer of 1 to 3.
Further, as Z ′ in the formula (7), one represented by any of the following formulas (10) to (17) is desirable.

In formulas (10) to (17), R ²¹ and R ²² are each a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms. This represents one selected from the group consisting of a substituted phenyl group, an unsubstituted phenyl group, an aralkyl group having 7 to 10 carbon atoms, and a halogen atom, W represents a divalent group, q and r each represent 1 Represents an integer of 10 or less, and t represents an integer of 1 or more and 3 or less, respectively.
W in the above formulas (16) to (17) is preferably any one of divalent groups represented by the following (18) to (26). However, in formula (25), u represents an integer of 0 or more and 3 or less.

In the general formula (II), Ar ⁵ is the aryl group of the above (1) to (7) exemplified in the explanation of Ar ¹ to Ar ⁴ when k is 0, and when k is 1, These are arylene groups obtained by removing a hydrogen atom from the above aryl groups (1) to (7).

  Specific examples of the compound represented by the general formula (I) include the following compounds. In addition, the compound shown by the said general formula (I) is not limited at all by these.

  The content of the reactive charge transporting material is, for example, (solid content concentration in the coating solution) is 80% by mass or more, desirably 90% by mass or more, and more desirably with respect to the total constituent components (solid content). Is 95% by mass or more. If this solid content concentration is less than 90% by mass, the electrical characteristics may be deteriorated. The upper limit of the content of the reactive charge transport material is not limited as long as other additives function effectively, and it is desirable that the content is higher.

Next, the guanamine compound will be described.
The guanamine compound is a compound having a guanamine skeleton (structure), and examples thereof include acetoguanamine, benzoguanamine, formoguanamine, steroguanamine, spiroguanamine, and cyclohexylguanamine.

  The guanamine compound is particularly preferably at least one of a compound represented by the following general formula (A) and a multimer thereof. Here, the multimer is an oligomer polymerized using the compound represented by the general formula (A) as a structural unit, and the degree of polymerization thereof is, for example, 2 or more and 200 or less (preferably 2 or more and 100 or less). In addition, the compound shown by general formula (A) may be used individually by 1 type, but may use 2 or more types together. In particular, when the compound represented by the general formula (A) is used as a mixture of two or more kinds, or used as a multimer (oligomer) having the same as a structural unit, the solubility in a solvent is improved.

In general formula (A), R ₁ is a linear or branched alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted phenyl group having 6 to 10 carbon atoms, or 4 to 10 carbon atoms. The following substituted or unsubstituted alicyclic hydrocarbon groups are shown. R ₂ to R ₅ each independently represent hydrogen, —CH ₂ —OH, or —CH ₂ —O—R ₆ . R ₆ represents a linear or branched alkyl group having 1 to 10 carbon atoms.
In the general formula (A), the alkyl group representing R ₁ has 1 to 10 carbon atoms, preferably 1 to 8 carbon atoms, more preferably 1 to 5 carbon atoms. . The alkyl group may be linear or branched.
In general formula (A), the phenyl group represented by R ₁ has 6 to 10 carbon atoms, and more preferably 6 to 8 carbon atoms. Examples of the substituent substituted with the phenyl group include a methyl group, an ethyl group, and a propyl group.
In general formula (A), the alicyclic hydrocarbon group representing R ₁ has 4 to 10 carbon atoms, and more preferably 5 to 8 carbon atoms. Examples of the substituent substituted with the alicyclic hydrocarbon group include a methyl group, an ethyl group, and a propyl group.
In the general formula (A), in “—CH ₂ —O—R ₆ ” representing R ₂ to R ₅ , the alkyl group representing R ₆ has 1 to 10 carbon atoms, and desirably has carbon atoms. 1 or less and 8 or more, and more preferably 1 or more and 6 or less. The alkyl group may be linear or branched. Desirably, a methyl group, an ethyl group, a butyl group, etc. are mentioned.

As the compound represented by the general formula (A), it is particularly desirable that R ₁ represents a substituted or unsubstituted phenyl group having 6 to 10 carbon atoms, and R ₂ to R ₅ are each independently —CH ₂ —O. is a compound that shows a -R _6. R ₆ is preferably selected from a methyl group and an n-butyl group.
The compound represented by the general formula (A) is synthesized by, for example, a known method using guanamine and formaldehyde (for example, edited by The Chemical Society of Japan, Experimental Chemistry 4th Edition, Volume 28, page 430).
Hereinafter, exemplary compounds: (A) -1 to (A) -42 are shown as specific examples of the compound represented by the general formula (A), but this embodiment is not limited thereto. The following specific examples are monomers, but multimers (oligomers) having these monomers as structural units may also be used. In the following exemplary compounds, “Me” represents a methyl group, “Bu” represents a butyl group, and “Ph” represents a phenyl group.

Moreover, as a commercial item of the compound shown by general formula (A), for example, super becamine (R) L-148-55, super becamine (R) 13-535, super becamine (R) L-145 -60, Superbecamine (R) TD-126 (manufactured by DIC), Nicarak BL-60, Nicarac BX-4000 (manufactured by Nippon Carbide), and the like.
In addition, the compound represented by the general formula (A) (including multimers) can be used in a suitable solvent such as toluene, xylene, ethyl acetate, etc., in order to remove the influence of residual catalyst after synthesis or after purchasing a commercial product. It may be dissolved and washed with distilled water, ion exchange water or the like, or may be removed by treatment with an ion exchange resin.

Next, the melamine compound will be described.
The melamine compound is a melamine skeleton (structure), and is particularly preferably at least one of a compound represented by the following general formula (B) and a multimer thereof. Here, the multimer is an oligomer polymerized using the compound represented by the general formula (B) as a structural unit in the same manner as the general formula (A), and the degree of polymerization thereof is, for example, 2 or more and 200 or less (preferably 2 or more). 100 or less). In addition, the compound shown by General formula (B) or its multimer may be used individually by 1 type, and may use 2 or more types together. Moreover, you may use together with the compound shown by the said general formula (A), or its multimer. In particular, when the compound represented by the general formula (B) is used as a mixture of two or more kinds or used as a multimer (oligomer) having the same as a structural unit, the solubility in a solvent is improved.

In General Formula (B), R ⁶ to R ¹¹ each independently represent a hydrogen atom, —CH ₂ —OH, —CH ₂ —O—R ¹² , —O—R ¹² , and R ¹² has 1 or more carbon atoms. The alkyl group which may branch 5 or less is shown. Examples of the alkyl group include a methyl group, an ethyl group, and a butyl group.
The compound represented by the general formula (B) is synthesized by a known method using, for example, melamine and formaldehyde (for example, synthesized in the same manner as the melamine resin in Experimental Chemistry Course 4th Edition, Volume 28, page 430). )
Hereinafter, exemplary compounds: (B) -1 to exemplary compound: (B) -8 are shown as specific examples of the compound represented by the general formula (B), but this embodiment is not limited thereto. Moreover, although the following specific examples show the thing of a monomer, the multimer (oligomer) which uses these as a structural unit may be sufficient.

  As a commercial item of the compound represented by the general formula (B), for example, Super Melami No. 90 (manufactured by NOF Corporation), Super Becamine (R) TD-139-60 (manufactured by DIC Corporation), Uban 2020 (manufactured by Mitsui Chemicals), Sumtex Resin M-3 (manufactured by Sumitomo Chemical Co., Ltd.), Nicarac MW -30 (made by Nippon Carbide).

  In addition, the compound represented by the general formula (B) (including multimers) can be used in an appropriate solvent such as toluene, xylene, ethyl acetate, etc., in order to remove the influence of residual catalyst after synthesis or after purchasing a commercial product. It may be dissolved and washed with distilled water, ion exchange water or the like, or may be removed by treatment with an ion exchange resin.

  Here, at least one content selected from a guanamine compound (a compound represented by the general formula (A)) and a melamine compound (a compound represented by the general formula (B)) (solid content concentration in the coating solution) is: For example, the content is preferably 0.1% by mass or more and 5% by mass or less, and more preferably 1% by mass or more and 3% by mass or less, based on the total constituent components (solid content) of the layer. If the solid content concentration is less than 0.1% by mass, it is difficult to obtain a dense film, so that sufficient strength is difficult to obtain. If it exceeds 5% by mass, electrical properties and ghost resistance (density unevenness due to image history) are exhibited. May get worse.

Hereinafter, the protective layer will be described in more detail.
For example, an antioxidant may be added to the surface protective layer for the purpose of suppressing deterioration due to an oxidizing gas such as ozone generated in the charging device.
Examples of antioxidants include hindered phenol antioxidants, aromatic amine antioxidants, hindered amine antioxidants, organic sulfur antioxidants, phosphite antioxidants, and dithiocarbamate antioxidants. Examples include known antioxidants such as oxidants, thiourea antioxidants, and benzimidazole antioxidants.

  In the protective layer, a phenol resin, a urea resin, an alkyd resin, or the like may be used in combination with a reactive charge transport material (for example, a compound represented by the general formula (I)). In addition, in order to improve the strength, a compound having more functional groups in one molecule such as spiroacetal guanamine resin (for example, “CTU-guanamine”, manufactured by Ajinomoto Fine Techno Co., Ltd.) is used as the material in the cross-linked product. Copolymerization is also effective.

  For the purpose of effectively suppressing oxidation by the discharge generated gas by adding the discharge generated gas so as not to adsorb too much, the protective layer may be used by mixing other thermosetting resins such as phenol resin. Good.

  For the protective layer. It is preferable to add a surfactant. The surfactant is not particularly limited as long as it is a surfactant containing at least one of a fluorine atom, an alkylene oxide structure, and a silicone structure. It is preferred because it has high affinity and compatibility, improves the film-forming property of the coating liquid for the protective layer, and suppresses wrinkles and unevenness of the protective layer.

  For the purpose of adjusting the film formability, flexibility, lubricity, and adhesiveness of the film, the protective layer may be mixed with a coupling agent or a fluorine compound. As this compound, various silane coupling agents and commercially available silicone hard coat agents are used.

Resin that dissolves in alcohol for the purpose of discharge gas resistance of protective layer, mechanical strength, scratch resistance, particle dispersibility, viscosity control, torque reduction, wear amount control, pot life (storability of coating liquid for layer formation), etc. May be added.
Here, the alcohol-soluble resin means a resin that dissolves 1% by mass or more in an alcohol having 5 or less carbon atoms. Examples of the resin soluble in the alcohol solvent include a polyvinyl acetal resin and a polyvinyl phenol resin.

Various particles may be added to the protective layer for the purpose of lowering the residual potential or improving the strength. Examples of the particles include silicon-containing particles and fluororesin particles.
The silicon-containing particles are particles containing silicon as a constituent element, and specific examples include colloidal silica and silicone particles.
The fluororesin particles are not particularly limited. For example, polytetrafluoroethylene, perfluoroalkoxy fluororesin, polychlorotrifluoroethylene, polyvinylidene fluoride, polydichlorodifluoroethylene, and tetrafluoroethylene-perfluoroalkyl vinyl ether. Examples thereof include particles of a polymer, a tetrafluoroethylene-hexafluoropropylene copolymer, a tetrafluoroethylene-ethylene copolymer, or a tetrafluoroethylene-hexafluoropropylene-perfluoroalkyl vinyl ether copolymer.
A fluoroalkyl group-containing copolymer may be used in combination with the fluororesin particles. Commercially available fluorinated alkyl group-containing copolymers include, for example, GF300, GF400 (manufactured by Toagosei Co., Ltd.), Surflon series (manufactured by AGC Seikekikal Co., Ltd.), footent series (manufactured by Neos), PF series (Kitamura Chemical) Co., Ltd.), Mega Fuck Series (manufactured by DIC), FC Series (manufactured by 3M), and the like.

An oil such as silicone oil may be added to the protective layer for the same purpose.
Metals, metal oxides, carbon black and the like may be added to the protective layer.

  The protective layer may be a cured film (cross-linked film) obtained by polymerizing (cross-linking) a reactive charge transport material and, if necessary, at least one selected from a guanamine compound and a melamine compound using an acid catalyst. desirable. Acid catalysts include aliphatic carboxylic acids such as acetic acid, chloroacetic acid, trichloroacetic acid, trifluoroacetic acid, oxalic acid, maleic acid, malonic acid, and lactic acid, aromatics such as benzoic acid, phthalic acid, terephthalic acid, and trimellitic acid Aliphatic and aromatic sulfonic acids such as carboxylic acid, methanesulfonic acid, dodecylsulfonic acid, benzenesulfonic acid, dodecylbenzenesulfonic acid, and naphthalenesulfonic acid are used, but it is desirable to use a sulfur-containing material.

  Here, the blending amount of the catalyst is desirably in the range of 0.1% by mass or more and 50% by mass or less, particularly preferably 10% by mass or more and 30% by mass or less, with respect to the total constituent components (solid content) of the layer. . When the amount is less than the above range, the catalytic activity may be too low, and when it exceeds the above range, the light resistance may be deteriorated. The light resistance refers to a phenomenon in which the irradiated portion causes a decrease in density when the photosensitive layer is exposed to light from the outside such as room light. The cause is not clear, but it is presumed that this is because a phenomenon similar to the optical memory effect occurs as disclosed in JP-A-5-099737.

  The protective layer having the above structure is formed using a protective layer-forming coating solution in which the above components are mixed. The coating liquid for forming the protective layer may be prepared without a solvent, or may be performed using a solvent as necessary. Such solvents are used singly or in combination of two or more, and preferably have a boiling point of 100 ° C. or lower. As the solvent, it is particularly preferable to use a solvent having at least one hydroxyl group (for example, alcohol).

In addition, when the coating liquid is obtained by reacting the above components, it may be simply mixed and dissolved, but it is room temperature (for example, 25 ° C.) to 100 ° C., preferably 30 ° C. to 80 ° C. for 10 minutes to 100 Heating may be performed for a period of time or less, preferably 1 hour or more and 50 hours or less. It is also desirable to irradiate ultrasonic waves at this time. Thereby, it is likely that a partial reaction proceeds, and it is easy to obtain a film with few coating film defects and little variation in thickness.
Then, the coating liquid for forming the protective layer is applied by a known method such as blade coating method, Mayer bar coating method, spray coating method, dip coating method, bead coating method, air knife coating method, curtain coating method, etc. Accordingly, for example, the protective layer is obtained by heating and curing at a temperature of 100 ° C. or higher and 170 ° C. or lower.

  The thickness of the protective layer is desirably set in the range of 3 μm to 40 μm, more desirably 5 μm to 35 μm, and even more desirably 5 μm to 15 μm.

In the above, the function-separated type electrophotographic photosensitive member has been described as an example. For example, when the single-layer type photosensitive layer (charge generation / charge transport layer) shown in FIG. 3 is formed, the content of the charge generation material is About 10% by mass or more and 85% by mass or less is desirable, and more desirably 20% by mass or more and 50% by mass or less. In addition, the content of the charge transport material is desirably 5% by mass or more and 50% by mass or less.
The method for forming the single-layer type photosensitive layer is the same as the method for forming the charge generation layer and the charge transport layer. The thickness of the single-layer photosensitive layer is preferably about 5 μm to 50 μm, and more preferably 10 μm to 40 μm.

[Charging device]
Examples of the charging device 20 include a contact charger using a conductive charging roller, a charging brush, a charging film, a charging rubber blade, a charging tube, and the like. Further, examples of the charging device 20 include a non-contact type roller charger and a known charger such as a scorotron charger using a corona discharge or a corotron charger. As the charging device 20, a contact charger is preferable.

[Exposure equipment]
Examples of the exposure apparatus 30 include optical system devices that expose the surface of the electrophotographic photoreceptor 10 with light such as semiconductor laser light, LED light, and liquid crystal shutter light imagewise. The wavelength of the light source is preferably within the spectral sensitivity region of the electrophotographic photoreceptor 10. As the wavelength of the semiconductor laser, for example, near infrared having an oscillation wavelength around 780 nm is preferable. However, the present invention is not limited to this wavelength, and a laser having an oscillation wavelength of 600 nm or a laser having an oscillation wavelength of 400 nm to 450 nm as a blue laser may be used. Further, as the exposure apparatus 30, for example, a surface emitting laser light source of a multi-beam output type is also effective for color image formation.

[Developer]
An example of the developing device 40 is a configuration in which a developing roll 41 disposed in the developing region facing the electrophotographic photosensitive member 10 is provided in a container that stores a two-component developer composed of toner and a carrier. The developing device 40 is not particularly limited as long as it is a device that develops with a two-component developer, and a known configuration is employed.

Here, the developer used in the developing device 40 will be described.
The developer may be a one-component developer made of toner, or a two-component developer containing toner and carrier.

  The toner includes, for example, toner particles containing a binder resin, a colorant, and, if necessary, other additives such as a release agent, and external additives as necessary.

The toner particles have an average shape factor (shape factor = (ML ² / A) × (π / 4) × 100), and ML represents the maximum length of the particles, where A represents the maximum length of the particles (Representing the projected area) is preferably from 100 to 150, more preferably from 105 to 145, and even more preferably from 110 to 140. Further, the toner preferably has a volume average particle diameter of 3 μm or more and 12 μm or less, more preferably 3.5 μm or more and 10 μm or less, and further preferably 4 μm or more and 9 μm or less.

  The toner particles are not particularly limited by the production method, and for example, a kneading and pulverizing method in which a binder resin, a colorant and a release agent, and a charge control agent and the like are added, if necessary, are kneaded, pulverized, and classified; A method of changing the shape of the particles obtained by the kneading and pulverization method by mechanical impact force or thermal energy; the polymerization monomer of the binder resin is emulsion-polymerized, the formed dispersion, the colorant and the release agent Emulsion polymerization aggregation method to obtain a toner particle by mixing a mold agent and, if necessary, a dispersion of a charge control agent, and agglomerating and heat-fusing; a polymerizable monomer for obtaining a binder resin, and coloring Suspension polymerization method in which a solution of an agent, a release agent and, if necessary, a charge control agent is suspended in an aqueous solvent for polymerization; a binder resin, a colorant and a release agent, and if necessary, a charge control agent Toner particles produced by a solution suspension method in which a solution such as a liquid is suspended in an aqueous solvent and granulated There will be used.

  Further, a known method such as a production method in which the toner particles obtained by the above method are used as a core, and agglomerated particles are further adhered and heated and fused to give a core-shell structure is used. The toner production method is preferably a suspension polymerization method, an emulsion polymerization aggregation method, or a dissolution suspension method in which an aqueous solvent is used from the viewpoint of shape control and particle size distribution control, and an emulsion polymerization aggregation method is particularly desirable.

  The toner is produced by mixing the toner particles and the external additive with a Henschel mixer or a V blender. Further, when the toner particles are produced by a wet method, they may be externally added by a wet method.

  When the toner is used as a two-component developer, the mixing ratio with the carrier is set at a known ratio. In addition, there is no restriction | limiting in particular as a carrier, For example, what carried out resin coating to the surface of a magnetic particle as a carrier is mentioned suitably.

[Transfer device]
As the transfer device 50, for example, a contact transfer charger using a belt, a roller, a film, a rubber blade or the like, or a known transfer charger such as a scorotron transfer charger using a corona discharge or a corotron transfer charger. Can be mentioned.

[Cleaning device]
The cleaning device 70 includes, for example, a casing 71, a cleaning blade 72, and a cleaning brush 73 disposed on the downstream side of the cleaning blade 72 in the rotation direction of the electrophotographic photosensitive member 10. Further, for example, a solid lubricant 74 is disposed in contact with the cleaning brush 73.

[Staticizer]
As the static elimination apparatus 80, the well-known static elimination apparatus provided with light sources, such as a tungsten lamp and LED, is mentioned, for example.

  Hereinafter, the operation of the image forming apparatus 101 according to the present embodiment will be described. First, the electrophotographic photoreceptor 10 rotates along the direction indicated by the arrow a, and at the same time is negatively charged by the charging device 20.

  The electrophotographic photoreceptor 10 whose surface is negatively charged by the charging device 20 is exposed by the exposure device 30, and a latent image is formed on the surface.

  When the portion where the latent image is formed on the electrophotographic photosensitive member 10 approaches the developing device 40, toner is attached to the latent image by the developing device 40 (developing roll 41), and a toner image is formed.

When the electrophotographic photosensitive member 10 on which the toner image is formed is further rotated in the direction of arrow a, the toner image is transferred onto the recording paper P by the transfer device 50. As a result, a toner image is formed on the recording paper P.
Thereafter, the surface of the electrophotographic photosensitive member 10 is cleaned by the cleaning device 70, and then the static elimination device 80 performs static elimination by irradiating the entire surface of the electrophotographic photosensitive member 10 with static elimination light. Then, charging is again performed by the charging device 20, and the next cycle (image process) is performed.

  The toner image is fixed on the recording paper P on which the image is formed by the fixing device 60.

For example, as illustrated in FIG. 3, the image forming apparatus 101 according to the present embodiment includes an electrophotographic photosensitive member 10, a charging device 20, an exposure device 30, a developing device 40, a cleaning device 70, and the like in a housing 11. The process cartridge 101 </ b> A in which the static eliminator 80 is housed integrally may be provided. The process cartridge 101A integrally contains a plurality of members and is attached to and detached from the image forming apparatus 101.
Note that the configuration of the process cartridge 101A is not limited to this, and for example, a device other than the above may be provided.

  In addition, the image forming apparatus 101 according to the present embodiment is not limited to the above configuration, and is, for example, a cleaning device around the electrophotographic photosensitive member 10 and downstream of the transfer device 50 in the rotation direction of the electrophotographic photosensitive member 10. A configuration in which a first static eliminating device for aligning the polarity of the remaining toner and facilitating removal with a cleaning brush may be provided on the upstream side of the electrophotographic photosensitive member in the rotational direction from 70.

  The image forming apparatus 101 according to the present embodiment is not limited to the above-described configuration, and a known configuration, for example, a toner image formed on the electrophotographic photosensitive member 10 is transferred to the intermediate transfer member and then transferred to the recording paper P. An intermediate transfer type image forming apparatus or a tandem type image forming apparatus may be used.

  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.

<Production of photoconductor>
[Photoreceptor 1]
-Undercoat layer-
Zinc oxide: (average particle diameter 70 nm: manufactured by Teika Co., Ltd .: specific surface area value 15 m ² / g) 100 parts by mass of 500 parts by mass of toluene was mixed with stirring, and silane coupling agent (KBM603: manufactured by Shin-Etsu Chemical Co., Ltd.) 1.0 mass Part was added and stirred for 2 hours. Thereafter, toluene was distilled off under reduced pressure and baked at 120 ° C. for 3 hours to obtain a silane coupling agent surface-treated zinc oxide pigment.
100 parts by mass of the surface-treated zinc oxide was stirred and mixed with 500 parts by mass of tetrahydrofuran, a solution prepared by dissolving 1 part by mass of alizarin in 50 parts by mass of tetrahydrofuran was added, and the mixture was stirred at 50 ° C. for 5 hours. Thereafter, the zinc oxide having alizarin attached to the surface was filtered off under reduced pressure, and further dried under reduced pressure at 60 ° C. to obtain an alizarin-added zinc oxide pigment.
60 parts by mass of alizarin-added zinc oxide pigment, 13.5 parts by mass of a curing agent (blocked isocyanate Sumijoule 3175 (manufactured by Sumitomo Bayern Urethane)), and 15 parts by mass of butyral resin (BM-1 (manufactured by Sekisui Chemical Co., Ltd.)) 38 parts by mass of the solution dissolved in 85 parts by mass and 25 parts by mass of methyl ethyl ketone were mixed, and dispersed for 2 hours with a sand mill using 1 mmφ glass beads to obtain a dispersion.

  Dioctyltin dilaurate: 0.005 parts by mass and silicone resin particle Tospearl 145 (manufactured by GE Toshiba Silicone): 40 parts by mass are added as catalysts to the resulting dispersion, followed by drying and curing at 170 ° C. for 40 minutes. A layer forming coating solution was obtained. This undercoat layer forming coating solution is applied on an aluminum substrate having a diameter of 84 mm, a length of 340 mm, and a wall thickness of 1 mm by a dip coating method. Formed.

-Charge generation layer-
Next, chloro having a strong diffraction peak at 7.4 °, 16.6 °, 25.5 °, and 28.3 ° in the Bragg angle (2θ ± 0.2 °) in the X-ray diffraction spectrum as a charge generation material. 1 part by weight of gallium phthalocyanine crystal is added to 100 parts by weight of butyl acetate together with 1 part by weight of polyvinyl butyral resin (trade name: ESREC BM-S, manufactured by Sekisui Chemical Co., Ltd.). Thus, a coating solution for forming a charge generation layer was obtained. The obtained coating solution was dip-coated on the undercoat layer and dried at 100 ° C. for 10 minutes to form a charge generation layer having a thickness of 0.2 μm.

-Charge transport layer-
Next, 2 parts by mass of the compound represented by the following structural formula 1 and 3 parts by mass of the polymer compound (viscosity average molecular weight: 39,000) represented by the following structural formula 2 are dissolved in 10 parts by mass of tetrahydrofuran and 5 parts by mass of toluene. Thus, a coating solution was obtained. The obtained coating solution was dip-coated on the charge generation layer and dried by heating at 130 ° C. for 40 minutes to form a charge transport layer having a thickness of 20 μm.

-Protective layer-
As a reactive charge transport material, 9.5 parts by mass of the compound represented by the following structural formula 3 (Exemplary Compound (I-21)), 35 parts by mass of cyclopentanol, 9 parts by mass of tetrahydrofuran, and 0.9 part by mass of distilled water were added. The mixture was mixed, 0.5 parts by mass of ion exchange resin (Amberlyst 15E) was added thereto, and the mixture was stirred at room temperature (25 ° C.) for hydrolysis for 2 hours. Further, 0.5 parts by mass of benzoguanamine resin (Exemplary Compound (A) -17: Nicalac BL-60, manufactured by Sanwa Chemical Co., Ltd.), 0.2 parts by mass of dimethylpolysiloxane, and NACURE 2500 (manufactured by King Industry) 0.1 A coating solution for forming a protective layer was prepared by adding parts by mass. This protective layer-forming coating solution was applied onto the charge transport layer by a dip coating method and dried at 152 ° C. for 50 minutes to form a protective layer having a thickness of about 8 μm.

  The photoreceptor 1 was produced through the above steps.

[Photoreceptor 2]
A photosensitive member obtained in the same manner as in the photosensitive member 1 except that a protective layer was formed by applying a coating solution for forming a protective layer on the charge transport layer in the photosensitive member 1 and then drying at 160 ° C. for 50 minutes. Photoconductor 2 was obtained.

[Photoreceptor 3]
In the photoreceptor 1, a photoreceptor obtained in the same manner as the photoreceptor 1 except that a protective layer was formed by applying a protective layer forming coating solution on the charge transport layer and then drying at 145 ° C. for 50 minutes. Photoconductor 3 was obtained.

[Photosensitive member 4]
In the photoreceptor 3, a photoreceptor obtained in the same manner as the photoreceptor 3 except that the film thickness of the charge transport layer was 25 μm was designated as the photoreceptor 4.

[Photoreceptor 5]
A photosensitive member obtained in the same manner as the photosensitive member 4 except that a protective layer was formed by applying a coating solution for forming a protective layer on the charge transporting layer and then drying at 152 ° C. for 50 minutes. Photoconductor 5 was obtained.

[Photoreceptor 6]
A photosensitive member obtained in the same manner as in the photosensitive member 4 except that a protective layer was formed by applying a coating solution for forming a protective layer on the charge transport layer and then drying at 140 ° C. for 50 minutes. Photoconductor 6 was obtained.

[Photoreceptor 7]
In the photoreceptor 1, a photoreceptor obtained in the same manner as the photoreceptor 1 except that a protective layer was formed by applying a coating solution for forming a protective layer on the charge transport layer and then drying at 163 ° C. for 50 minutes. Photoconductor 7 was obtained.

[Photoreceptor 8]
In the photoreceptor 1, a photoreceptor obtained in the same manner as the photoreceptor 1 except that a protective layer was formed by applying a coating solution for forming a protective layer on the charge transport layer and then drying at 142 ° C. for 50 minutes. Photoconductor 8 was obtained.

[Photoreceptor 9]
A photosensitive member obtained in the same manner as in the photosensitive member 4 except that a protective layer was formed by applying a coating solution for forming a protective layer on the charge transporting layer and then drying at 155 ° C. for 50 minutes. Photoconductor 9 was obtained.

[Photosensitive member 10]
In the photoreceptor 4, a photoreceptor obtained in the same manner as the photoreceptor 4 except that a protective layer was formed by applying a coating solution for forming a protective layer on the charge transport layer and then drying at 137 ° C. for 50 minutes. Photoconductor 10 was obtained.

[Photoreceptor 11]
In the photoreceptor 1, a photoreceptor obtained in the same manner as the photoreceptor 3 except that the film thickness of the charge transport layer was set to 15 μm was designated as the photoreceptor 11.

<Examples 1-6, Comparative Examples 1-5>
The photosensitive member according to Table 1 was mounted on an image forming apparatus [Fuji Xerox Co., Ltd., Core 1000 Press speed increasing remodeling machine.
The main configuration of the image forming apparatus is as follows.
・ Charging device: Storocolon (Charging voltage: DC voltage -700V)
・ Transfer device: Strocolon (Transfer voltage: DC voltage 700V)
-Static elimination device: Xenon flash lamp (static neutralization light intensity: 5 mJ / m ² )
-Time to charge after static elimination Tc: 68 (msec)
-Time from static elimination to development Td: 167 (msec)

<Evaluation>
(Measurement of ΔV of photoreceptor)
ΔV of each photoconductor was measured as follows. The ΔV of each photoconductor was measured under conditions corresponding to the configuration of the image forming apparatus equipped with the photoconductor.
Specifically, in an environment of a temperature of 22 ° C. and a humidity of 55%, the photoconductor is charged to −700 V with a scorotron corresponding to a charging device, and is passed through a transmission-type potential probe with pulsed light (with a xenon flash lamp corresponding to a static eliminating device). Irradiation with an irradiation light intensity of 5 mJ / m ² ) was performed to remove static electricity, and the surface potential time change immediately after the light irradiation was measured with a transmission potential probe.
Then, the surface potential of the photosensitive member (corresponding to the surface potential of the unexposed area) after the elapse of 68 (msec) immediately after the light irradiation corresponding to the time Tc until charge after neutralization, and the light corresponding to the time Td until after development after neutralization The surface potential of the photoconductor (corresponding to the surface potential of the unexposed portion) after 167 (msec) elapsed immediately after irradiation was measured, and the potential difference ΔV was determined.

(Measurement of ΔC of photoreceptor)
ΔC of each photoconductor was measured as follows. The ΔV of each photoconductor was measured under conditions corresponding to the configuration of the image forming apparatus equipped with the photoconductor.
First, in an environment of a temperature of 22 ° C. and a humidity of 55%, the photoconductor is charged with a scorotron corresponding to a charging device, and pulsed light (irradiation light intensity 5 mJ / m ² ) is irradiated with a xenon flash lamp corresponding to a static eliminator. While repeatedly removing all the charges, the grid voltage of the scorotron is increased from 0 V to -1400 V every 100 V, and the surface potential after charging of the photoreceptor and the inflow current of the photoreceptor are measured. The inflow current of the photoconductor is divided by the charged area to obtain the charge Q to be given to the surface of the photoconductor, and a QV graph in which the horizontal axis is the charge amount Q and the vertical axis is the surface potential V is created. Using data in which the surface potential of the photoreceptor is in the range of −200 V to −600 V, linear approximation is performed by the least square method, and the capacitance C1 (corresponding to the capacitance when there is no transfer) is determined from the slope of the obtained straight line. )
Next, after measuring the surface potential of the photosensitive member after charging, the measurement was performed in the same manner except that a transfer voltage (DC voltage 700 V) was applied with a strobe colon corresponding to the transfer device. Equivalent to the capacitance).
Then, from the obtained capacitances C1 and C2, the reduction rate [C2 / C1] (%) of the capacitance of the photosensitive member due to transfer was equivalent to the reduction rate (%) of the capacitance of the unexposed portion. .

(Image quality evaluation)
An image formation test was performed using an image forming apparatus equipped with each photoconductor.
Specifically, the ghost evaluation of the print image is visually performed, and when the image history appears dark, it is determined as a positive ghost, and when the image history appears light, it is determined as a negative ghost. Further, the density unevenness evaluation of the halftone image was visually performed.

  The results are shown in Table 1.

  From the above results, it can be seen that in this embodiment, both the ghost and the density unevenness are suppressed in the image quality evaluation as compared with the comparative example.

DESCRIPTION OF SYMBOLS 1 Undercoat layer, 2 Charge generation layer, 3 Charge transport layer, 4 Conductive support body, 5 Protective layer, 10 Electrophotographic photosensitive member, 11 Case, 20 Charging device, 30 Exposure device, 40 Developing device, 41 Developing roll , 50 transfer device, 60 fixing device, 70 cleaning device, 71 housing, 72 cleaning blade, 72A support member, 73 cleaning brush, 74 lubricant, 80 static elimination device, 101A process cartridge, 101 image forming device

Claims (2)

An electrophotographic photoreceptor satisfying the following formulas (1) and (2);
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 formed on the electrophotographic photosensitive member into a toner image by the developer;
Transfer means for transferring the toner image to a transfer object;
After the toner image is transferred to the transfer medium, before the surface of the electrophotographic photosensitive member is charged, the surface of the electrophotographic photosensitive member is irradiated with a neutralizing light to remove static electricity;
With
An image forming apparatus in which the time until the surface of the electrophotographic photosensitive member is charged after being charged is 100 msec or less.
Formula (1): (ΔV / 20) −1 ≦ ΔC ≦ (ΔV / 20) +1
Formula (2): ΔV ≧ 30
(In Formula (1) and Formula (2), ΔV represents an unexposed portion of the electrophotographic photosensitive member when a time Tc (msec) until charging after the surface of the electrophotographic photosensitive member has been neutralized has elapsed. And the surface potential (V) of the unexposed portion of the electrophotographic photosensitive member when the time Td (msec) until development after the surface of the electrophotographic photosensitive member has been neutralized, (ΔC represents a reduction rate (%) of the electrostatic capacity of the unexposed portion of the electrophotographic photosensitive member due to the transfer of the toner image.) An electrophotographic photoreceptor satisfying the following formulas (1) and (2);
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 formed on the electrophotographic photosensitive member into a toner image by the developer;
Transfer means for transferring the toner image to a transfer object;
After the toner image is transferred to the transfer medium, before the surface of the electrophotographic photosensitive member is charged, the surface of the electrophotographic photosensitive member is irradiated with a neutralizing light to remove static electricity;
With
The time until the surface of the electrophotographic photosensitive member is neutralized and charged is 100 msec or less,
A process cartridge attached to and detached from the image forming apparatus.
Formula (1): (ΔV / 20) −1 ≦ ΔC ≦ (ΔV / 20) +1
Formula (2): ΔV ≧ 30
(In Formula (1) and Formula (2), ΔV represents an unexposed portion of the electrophotographic photosensitive member when a time Tc (msec) until charging after the surface of the electrophotographic photosensitive member has been neutralized has elapsed. And the surface potential (V) of the unexposed portion of the electrophotographic photosensitive member when the time Td (msec) until development after the surface of the electrophotographic photosensitive member has been neutralized, (ΔC represents a reduction rate (%) of the electrostatic capacity of the unexposed portion of the electrophotographic photosensitive member due to the transfer of the toner image.)