JP2015184494A - Electrophotographic photoreceptor, process cartridge, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor that can suppress unevenness in density of halftone images after repeated image formation, and the occurrence of a change in density due to the history of the previous cycle.SOLUTION: There is provided an electrophotographic photoreceptor that includes: a conductive substrate 1; an undercoat layer 2 that is arranged on the conductive substrate and contains a binder resin and, as surface treatment particles in which the surface of metal oxide particles has been treated with a silane coupling agent having an amino group, first surface treatment particles having a BET specific surface area of 10 m/g or more and 15 m/g or less and second surface treatment particles having a BET specific surface area of 18 m/g or more and 30 m/g or less; and a photosensitive layer 3 that is arranged on the undercoat layer.

Description

  The present invention relates to an electrophotographic photosensitive member, a process cartridge, and an image forming apparatus.

  An electrophotographic image forming apparatus has high speed and high printing quality, and is used in image forming apparatuses such as copying machines and laser beam printers. As a photoreceptor used in an image forming apparatus, an organic photoreceptor using an organic photoconductive material has become the mainstream. When producing an organic photoreceptor, for example, an undercoat layer (sometimes referred to as an intermediate layer) is formed on an aluminum substrate, and then a photosensitive layer, in particular, a photosensitive layer comprising a charge generation layer and a charge transport layer is formed. Often formed.

  For example, Patent Document 1 discloses an electrophotographic photosensitive member having a photosensitive layer through an intermediate layer on a conductive support, wherein the intermediate layer contains a specific polyamide resin. It is disclosed.

  In Patent Document 2, in an image forming apparatus that forms an image by transferring a toner image formed on a photoconductor to a recording medium, the photoconductor is formed around a conductive base material and the conductive base material. And a photosensitive layer formed around the intermediate layer, wherein the intermediate layer contains fine metal oxide particles having an average particle size of 100 nm or less in the binder resin. An image forming apparatus is disclosed.

  In Patent Document 3, in an electrophotographic photosensitive member in which a photoconductive layer is provided on a conductive substrate, a white pigment and a binder resin are main components between the conductive substrate and the photoconductive layer, and the white pigment and An intermediate layer having a binder resin usage ratio in the range of 1/1 to 3/1 by volume ratio was provided, and an undercoat layer was formed between the conductive substrate and the intermediate layer. An electrophotographic photosensitive member is disclosed.

Patent Document 4 discloses an electrophotographic photosensitive member comprising a conductive substrate, an intermediate layer formed on the substrate, and a photosensitive layer formed on the intermediate layer, wherein the intermediate layer is a metal oxide. And a volume resistance of 10 ⁸ to 10 ¹³ Ω · cm when an electric field of 10 ⁶ V / m is applied at 28 ° C. and 85% RH, and 15 ° C. and 15% RH The volume resistance when an electric field of 10 ⁶ V / m is applied at 28 ° C. and 85% RH is 500 times or less of the volume resistance when an electric field of 10 ⁶ V / m is applied. A photoreceptor is disclosed.

  Patent Document 5 includes an electrophotographic photosensitive member, a charging unit, an exposing unit, a developing unit, and a transferring unit, and an image that is charged, exposed, developed, and transferred while moving the outer peripheral surface of the electrophotographic photosensitive member in a predetermined direction. The forming apparatus further comprises control means for controlling the moving speed of the outer peripheral surface of the electrophotographic photosensitive member so that the time required from charging to development is variable, and the electrophotographic photosensitive member is at least an undercoat layer And an photosensitive layer, and the undercoat layer contains at least a metal oxide fine particle and an acceptor compound having a group capable of reacting with the metal oxide fine particle. .

Japanese Patent Laid-Open No. 5-11483 JP 2002-123028 A Japanese Patent Laid-Open No. 5-80572 JP 2003-186219 A JP 2006-30698 A

  SUMMARY OF THE INVENTION An object of the present invention is to provide an electrophotographic photosensitive member that suppresses the occurrence of density unevenness in a halftone image and the change in density due to the history of the previous cycle (hereinafter referred to as “ghost”) when image formation is repeated. And

In order to achieve the above object, the following invention is provided.
The invention according to claim 1 is a surface-treated particle that is disposed on the conductive substrate and is surface-treated with a binder resin and a metal oxide particle with a silane coupling agent having an amino group. The first surface-treated particles having a BET specific surface area of 10 m ² / g to 15 m ² / g and the second surface-treated particles having a BET specific surface area of 18 m ² / g to 30 m ² / g An electrophotographic photosensitive member having a drawing layer and a photosensitive layer disposed on the undercoat layer.

  The invention according to claim 2 is the electrophotographic photosensitive member according to claim 1, wherein the metal oxide particles are at least one selected from the group consisting of tin oxide, titanium oxide, and zinc oxide.

  In the invention according to claim 3, in the first surface-treated particles and the second surface-treated particles, a surface treatment amount of the silane coupling agent having an amino group with respect to the metal oxide particles is 0.05 mass, respectively. The electrophotographic photosensitive member according to claim 1, wherein the electrophotographic photosensitive member is from 1% to 1.5% by mass.

The invention according to claim 4 is the electrophotographic photosensitive member according to any one of claims 1 to 3, wherein the undercoat layer further contains an electron-accepting compound.
The invention according to claim 5 is the electrophotographic photosensitive member according to claim 4, wherein the electron-accepting compound is an anthraquinone derivative.
The invention according to claim 6 is the electrophotographic photosensitive member according to claim 5, wherein the anthraquinone derivative is represented by the following general formula (1).

(In general formula (1), n1 and n2 each independently represent an integer of 0 or more and 3 or less, provided that at least one of n1 and n2 independently represents an integer of 1 or more and 3 or less. M1 and m2 Each independently represents an integer of 0 or 1. R ¹ and R ² each independently represents an alkyl group having 1 to 10 carbon atoms or an alkoxy group having 1 to 10 carbon atoms.

  The invention according to claim 7 is the electrophotographic photoreceptor according to any one of claims 1 to 6, wherein the thickness of the undercoat layer is 15 μm or more and 30 μm or less.

  The invention according to claim 8 is the invention according to any one of claims 1 to 7, wherein the content of the second surface treatment particles in the undercoat layer is larger than the content of the first surface treatment particles. The electrophotographic photoreceptor described in 1.

  A ninth aspect of the present invention is a process cartridge comprising the electrophotographic photosensitive member according to any one of the first to eighth aspects, wherein the process cartridge is detachable from an image forming apparatus.

  The process cartridge according to claim 9, further comprising a contact charging type charging unit that contacts the electrophotographic photosensitive member to charge the surface of the electrophotographic photosensitive member.

  The invention according to claim 11 is the electrophotographic photosensitive member according to any one of claims 1 to 8, charging means for charging the surface of the electrophotographic photosensitive member, and the charged electrophotographic photosensitive member. Development that forms a toner image by developing the electrostatic latent image formed on the surface of the electrophotographic photosensitive member with an electrostatic latent image forming unit that forms an electrostatic latent image on the surface of the toner and a developer containing toner An image forming apparatus comprising: means; and transfer means for transferring the toner image to the surface of the recording medium.

  12. The image forming apparatus according to claim 12, wherein the charging unit is a contact charging type charging unit.

According to the invention of claim 1, undercoat layer, as the surface treated particles surface-treated with a silane coupling agent having an amino group metal oxide particles, BET specific surface area of 10 m 2 / ^g or more 15 m ² Halftone when image formation is repeated as compared with the case where the first surface-treated particles having a BET specific surface area of 18 m ² / g or less and the second surface-treated particles having a BET specific surface area of 18 m ² / g or more and 30 m ² / g or less are not included. An electrophotographic photosensitive member is provided in which the occurrence of image density unevenness and ghosting is suppressed.

  According to the invention of claim 3, compared with the case where the surface treatment amount of the silane coupling agent having an amino group with respect to the metal oxide particles is out of the range of 0.05% by mass or more and 1.5% by mass or less, the image An electrophotographic photosensitive member is provided in which the occurrence of an initial ghost when the formation is repeated is suppressed.

  According to the inventions according to claims 4, 5, and 6, there is provided an electrophotographic photosensitive member in which an increase in residual potential when image formation is repeated is suppressed as compared with a case where the undercoat layer does not contain an electron accepting compound. Is done.

  According to the seventh aspect of the present invention, compared to the case where the thickness of the undercoat layer is outside the range of 15 μm or more and 30 μm or less, the occurrence of leakage due to an external foreign substance (for a case of less than 15 μm) (over 30 μm) In some cases, an electrophotographic photoreceptor is provided in which the increase in residual potential is suppressed.

According to the invention according to claim 8, the BET specific surface area is 10 m ² / g as the surface-treated particles in which the undercoat layer of the electrophotographic photoreceptor is surface-treated with the silane coupling agent having an amino group on the metal oxide particles. Compared with the case where the first surface-treated particles having a surface area of 15 m ² / g or less and the second surface-treated particles having a BET specific surface area of 18 m ² / g or more and 30 m ² / g or less are not included, halftone during repeated use A process cartridge is provided in which density unevenness and ghosting of an image are suppressed.
According to the ninth aspect of the present invention, the density unevenness of the halftone image is provided even when the charging means of the contact charging method in which the density unevenness of the halftone image and the ghost are easily generated when the image formation is repeated is provided. And a process cartridge in which the occurrence of ghosts is suppressed.

According to the invention of claim 10, the undercoat layer of the electrophotographic photosensitive member has a BET specific surface area of 10 m ² / g as surface-treated particles obtained by surface-treating metal oxide particles with a silane coupling agent having an amino group. When image formation is repeated as compared with the case where the first surface-treated particles having a surface area of 15 m ² / g or less and the second surface-treated particles having a BET specific surface area of 18 m ² / g to 30 m ² / g are not included. An image forming apparatus is provided in which density unevenness and ghosting of halftone images are suppressed.
According to the eleventh aspect of the present invention, the density unevenness of the halftone image is provided even when the charging means of the contact charging method that easily generates the density unevenness and ghost of the halftone image when the image formation is repeated is provided. And an image forming apparatus in which the occurrence of ghosts is suppressed.

It is the schematic which shows an example of the layer structure of the electrophotographic photoreceptor which concerns on this embodiment. It is the schematic which shows the other example of the layer structure of the electrophotographic photoreceptor which concerns on this embodiment. It is the schematic which shows the other example of the layer structure of the electrophotographic photoreceptor which concerns on this embodiment. It is the schematic which shows the other example of the layer structure of the electrophotographic photoreceptor which concerns on this embodiment. It is the schematic which shows the other example of the layer structure of the electrophotographic photoreceptor which concerns on this embodiment. It is the schematic which shows the other example of the layer structure of the electrophotographic photoreceptor which concerns on this embodiment. 1 is a schematic configuration diagram illustrating an example of an image forming apparatus according to an exemplary embodiment. It is a schematic block diagram which shows the other example of the image forming apparatus which concerns on this embodiment. In an Example, it is a schematic diagram which shows the chart used for image quality evaluation.

  Hereinafter, the electrophotographic photoreceptor according to the exemplary embodiment will be described in detail with reference to the drawings.

[Electrophotographic photoreceptor]
An electrophotographic photoreceptor according to the exemplary embodiment (hereinafter sometimes simply referred to as “photoreceptor”) includes a conductive substrate, a binder resin, and a metal oxide disposed on the conductive substrate. As the surface-treated particles obtained by surface-treating the particles with a silane coupling agent having an amino group, the first surface-treated particles having a BET specific surface area of 10 m ² / g to 15 m ² / g and a BET specific surface area of 18 m ² / g The subbing layer includes the second surface-treated particles that are 30 m ² / g or less, and the photosensitive layer disposed on the subbing layer. Hereinafter, the term “surface-treated particles” simply means common to the first surface-treated particles and the second surface-treated particles.

  When the image forming apparatus is performed using the electrophotographic photosensitive member according to the present embodiment, density unevenness and ghosting of a halftone image when image formation is repeated are suppressed. The reason for this is not clear, but is thought to be due to the following reasons.

If the dispersion time of the metal oxide particles in the coating solution for forming the undercoat layer is short, the filter of the circulation type coating device is likely to be clogged, and if the dispersion time is long, the electrical characteristics are likely to fluctuate when used for a long time. .
On the other hand, the dispersibility of the metal oxide particles in the coating solution depends on the specific surface area. When the specific surface area is small, the dispersion is fast, and when the specific surface area is large, the dispersion tends to be slow. Further, when the surface treatment amount of the metal oxide particles is small, the dispersion is fast, and when the surface treatment amount is large, the dispersion tends to be slow.
Then, two types of metal oxide particles (first surface-treated particles and second surface-treated particles) that are surface-treated with a silane coupling agent having an amino group and each have a BET specific surface area within the above range are used in combination. It is considered that the dispersibility is in an appropriate range by using the applied coating solution. Therefore, it is considered that an undercoat layer in which aggregation of surface-treated particles is suppressed is formed by using this coating liquid, and generation of density unevenness and ghost in a halftone image is suppressed.

In particular, in an image forming apparatus (process cartridge) including a contact charging type charging unit, local discharge is likely to occur, and abnormal discharge is more likely to occur when the in-plane unevenness of the undercoat layer is large. It is done.
For this reason, in an image forming apparatus (process cartridge) including a contact charging type charging unit, halftone image density unevenness and ghost are likely to occur. However, when the electrophotographic photosensitive member according to this embodiment is applied, a halftone image is obtained. It is easy to obtain an image in which the density unevenness and the ghost are suppressed.

1 to 6 are schematic views showing examples of the layer structure of the photoreceptor according to the present embodiment. The photoreceptor shown in FIG. 1 includes a conductive substrate 1, an undercoat layer 2 formed on the conductive substrate 1, and a photosensitive layer 3 formed on the undercoat layer 2. ing.
Further, as shown in FIG. 2, the photosensitive layer 3 may have a two-layer structure of a charge generation layer 31 and a charge transport layer 32. Further, as shown in FIGS. 3 and 4, a protective layer 5 may be provided on the photosensitive layer 3 or the charge transport layer 32. 5 and 6, an intermediate layer 4 may be provided between the undercoat layer 2 and the photosensitive layer 3 or between the undercoat layer 2 and the charge generation layer 31.

  In addition, although the intermediate | middle layer 4 has shown the aspect provided between the undercoat layer 2 and the photosensitive layer 3, or between the undercoat layer 2 and the electric charge generation layer 31, the electroconductive base material 1 and an undercoat layer are shown. 2 may be provided. Of course, the aspect which does not provide the intermediate | middle layer 4 may be sufficient.

  Next, each element of the electrophotographic photosensitive member according to this embodiment will be described. Note that the reference numerals are omitted.

(Conductive substrate)
Examples of the conductive substrate include a metal plate, metal drum, and metal belt containing metal (aluminum, copper, zinc, chromium, nickel, molybdenum, vanadium, indium, gold, platinum, etc.) or an alloy (stainless steel, etc.). Etc. Examples of the conductive substrate include paper, resin film, and belt on which a conductive compound (for example, conductive polymer, indium oxide, etc.), a metal (for example, aluminum, palladium, gold, etc.) or an alloy is applied, evaporated or laminated. And so on. Here, “conductive” means that the volume resistivity is less than 10 ¹³ Ωcm.

  When the electrophotographic photosensitive member is used in a laser printer, the surface of the conductive substrate has a center line average roughness Ra of 0.04 μm or more and 0.0.mu.m for the purpose of suppressing interference fringes generated when laser light is irradiated. It is preferable that the surface is roughened to 5 μm or less. When non-interfering light is used as a light source, roughening for preventing interference fringes is not particularly required, but it is suitable for extending the life because it suppresses generation of defects due to irregularities on the surface of the conductive substrate.

  Examples of the roughening method include wet honing performed by suspending an abrasive in water and spraying it on a support, centerless grinding in which a conductive base material is pressed against a rotating grindstone, and grinding is continuously performed. And anodizing treatment.

  As a roughening method, without roughening the surface of the conductive substrate, conductive or semiconductive powder is dispersed in the resin to form a layer on the surface of the conductive substrate. Also, a method of roughening with particles dispersed in the layer can be mentioned.

  In the roughening treatment by anodic oxidation, a metal (for example, aluminum) conductive substrate is used as an anode to form an oxide film on the surface of the conductive substrate by anodizing in an electrolyte solution. Examples of the electrolyte solution include a sulfuric acid solution and an oxalic acid solution. However, the porous anodic oxide film formed by anodic oxidation is chemically active as it is, easily contaminated, and has a large resistance fluctuation due to the environment. Therefore, the pores of the oxide film are blocked by the volume expansion due to the hydration reaction in pressurized water vapor or boiling water (a metal salt such as nickel may be added) against the porous anodic oxide film, and more stable hydration oxidation It is preferable to perform a sealing treatment for changing to a product.

  The thickness of the anodized film is preferably, for example, 0.3 μm or more and 15 μm or less. When this film thickness is within the above range, the barrier property against implantation tends to be exhibited, and the increase in residual potential due to repeated use tends to be suppressed.

The conductive substrate may be subjected to treatment with an acidic treatment liquid or boehmite treatment.
The treatment with the acidic treatment liquid is performed as follows, for example. First, an acidic treatment liquid containing phosphoric acid, chromic acid and hydrofluoric acid is prepared. The mixing ratio of phosphoric acid, chromic acid and hydrofluoric acid in the acidic treatment liquid is, for example, in the range of 10% by mass to 11% by mass of phosphoric acid, in the range of 3% by mass to 5% by mass of chromic acid, The concentration of these acids is preferably in the range of 13.5% by mass or more and 18% by mass or less. The treatment temperature is preferably 42 ° C. or higher and 48 ° C. or lower, for example. The film thickness is preferably from 0.3 μm to 15 μm.

  The boehmite treatment is performed, for example, by immersing in pure water of 90 ° C. or higher and 100 ° C. or lower for 5 minutes to 60 minutes, or by contacting with heated steam of 90 ° C. or higher and 120 ° C. or lower for 5 minutes to 60 minutes. The film thickness is preferably 0.1 μm or more and 5 μm or less. This may be further anodized using an electrolyte solution with low film solubility such as adipic acid, boric acid, borate, phosphate, phthalate, maleate, benzoate, tartrate, citrate, etc. Good.

(Undercoat layer)
The subbing layer has a BET specific surface area of 10 m ² / g or more and 15 m ² / g or less as surface-treated particles obtained by surface-treating the binder resin and the metal oxide particles with a silane coupling agent having an amino group. 1 and ^2nd surface treatment particle | grains whose BET specific surface area is 18 m < ² > / g or more and 30 m < ² > / g or less, Preferably it is comprised including the electron-accepting compound further.

  In addition, the BET specific surface area of the surface treatment particles is a BET specific surface area measuring instrument (manufactured by Shimadzu Corporation: Flow Soap) for the metal oxide particles (surface treatment particles) after being surface-treated with a silane coupling agent having an amino group. II2300) and measured by the nitrogen substitution method.

-Binder resin As the binder resin, for example, acetal resin (for example, polyvinyl butyral), polyvinyl alcohol resin, casein, polyamide resin, cellulose resin, gelatin, polyurethane resin, polyester resin, methacrylic resin, acrylic resin, polyvinyl chloride Examples thereof include polymer resin compounds such as resins, polyvinyl acetate resins, vinyl chloride-vinyl acetate-maleic anhydride resins, silicone resins, silicone-alkyd resins, phenol resins, phenol-formaldehyde resins, and melamine resins. Moreover, the resin obtained by reaction of these resin and a hardening | curing agent is also mentioned.

-Surface-treated particles As the surface-treated particles in which the metal oxide particles are surface-treated with a silane coupling agent having an amino group, the BET specific surface area is 10 m ² / g or more and 15 m ² / g or less. Surface-treated particles and ^second surface-treated particles having a BET specific surface area of 18 m ² / g or more and 30 m ² / g or less.

From the viewpoint of suppressing density unevenness and ghosting in the halftone image, the BET specific surface area of the first surface-treated particles is preferably 12 m ² / g or more and 14 m ² / g or less, and the BET of the second surface-treated particles is The specific surface area is preferably 19 m ² / g or more and 22 m ² / g or less.

Examples of the metal oxide particles include particles of antimony oxide, indium oxide, tin oxide, titanium oxide, zinc oxide and the like.
Among these, as the metal oxide particles, tin oxide, titanium oxide, and zinc oxide particles are preferable from the viewpoint of suppressing an increase in residual potential.
The constituent material of the metal oxide particles (first metal oxide particles) constituting the first surface treatment particles and the metal oxide particles (second metal oxide particles) constituting the second surface treatment particles May be different, but are preferably of the same type.

  As the metal oxide particles, a conductive powder having a particle size of 100 nm or less, particularly 10 nm or more and 100 nm or less is preferably used. The particle size here means an average primary particle size. The average primary particle size of the metal oxide particles is a value observed and measured by SEM (scanning electron microscope), and is an average value measured for 50 randomly selected metal oxide particles.

The metal oxide particles preferably have a powder resistance of 10 ⁴ Ω · cm to 10 ¹⁰ Ω · cm. As a result, it becomes easy for the undercoat layer to obtain an appropriate impedance at a frequency corresponding to the electrophotographic process speed.
If the resistance value of the metal oxide particles is lower than 10 ⁴ Ω · cm, the slope of the dependency of the impedance on the particle addition amount is too large, and it may be difficult to control the impedance. On the other hand, if the resistance value of the metal oxide particles is higher than 10 ¹⁰ Ω · cm, the residual potential may be increased.

In order to obtain the first surface-treated particles and the second surface-treated particles, for example, metal oxide particles having a BET specific surface area corresponding to each surface-treated particle are used, and the surface by the silane coupling agent having an amino group is used. What is necessary is just to process. Commercially available metal oxide particles may be used.
Examples of commercially available metal oxide particles constituting the first surface-treated particles (BET specific surface area: 10 m ² / g or more and 15 m ² / g or less) include Teika Corporation zinc oxide MZ-150 and titanium oxide MT-100. .
Commercially available metal oxide particles constituting the second surface-treated particles (BET specific surface area: 18 m ² / g or more and 30 m ² / g or less) include Teika Corporation zinc oxide MZ-200 and titanium oxide MT-300. .

  Examples of the silane coupling agent having an amino group include γ-aminopropyltriethoxysilane, N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-amino. Examples include, but are not limited to, propylmethylmethoxysilane and N, N-bis (β-hydroxyethyl) -γ-aminopropyltriethoxysilane. These coupling agents having an amino group can be used in combination of two or more.

  The surface treatment amount of the silane coupling agent having an amino group in the surface-treated particles is preferably 0.05% by mass or more and 1.5% by mass or less, more preferably 0.1% by mass with respect to the metal oxide particles. The mass is 1.0% by mass or more. When the surface treatment amount of the silane coupling agent having an amino group with respect to the metal oxide particles is 0.05% by mass or more and 1.5% by mass or less, aggregation of the surface treatment particles is suppressed and generation of initial ghost is suppressed. Is done.

In addition, the processing amount of the silane coupling agent which has an amino group is measured as follows.
There are analysis methods such as FT-IR method, 29Si solid state NMR method, thermal analysis, XPS, etc., but FT-IR method is the simplest. In the FT-IR method, the normal KBr tablet method or the ATR method may be used. A small amount of treated metal oxide particles (surface-treated particles) are mixed with KBr, and FT-IR is measured to measure the treatment amount of the silane coupling agent having an amino group.

  The metal oxide particles may be subjected to a heat treatment after the surface treatment with the above-described silane coupling agent having an amino group to improve the environmental dependency of the resistance value, if necessary. The heat treatment temperature is preferably, for example, 150 ° C. or more and 300 ° C. or less, and the treatment time is 30 minutes or more and 5 hours or less.

  The content of the surface-treated particles in the undercoat layer (the total amount of the first surface-treated particles and the second surface-treated particles) is preferably 30% by mass or more and 60% by mass or less, and 35% by mass from the viewpoint of maintaining electrical characteristics. % To 55% by mass is more desirable.

  Moreover, it is desirable that the content of the second surface treatment particles in the undercoat layer is larger than the content of the first surface treatment particles. The content ratio of the second surface treatment particles to the total content of the first surface treatment particles and the second surface treatment particles contained in the undercoat layer is preferably 55% by mass or more and 85% by mass or less, More preferably, it is at least 70% by mass.

-Electron-accepting compound The electron-accepting compound is a material that chemically reacts with the surface of metal oxide particles (surface-treated particles) surface-treated with a silane coupling agent having an amino group, contained in the undercoat layer, or It is a material that adsorbs to the surface of the surface-treated particles, and can selectively exist on the surface of the surface-treated particles.

As the electron accepting compound, an electron accepting compound having an acidic group is preferably used. Examples of the acidic group include a hydroxyl group (phenolic hydroxyl group), a carboxyl group, and a sulfonyl group.
Specific examples of the electron-accepting compound include quinone series, anthraquinone series, coumarin series, phthalocyanine series, triphenylmethane series, anthocyanin series, flavone series, fullerene series, ruthenium complex, xanthene series, benzoxazine series, and porphyrin series. Compounds.
In particular, as an electron-accepting compound, an anthraquinone-based material (anthraquinone derivative) is desirable in consideration of the density unevenness of a halftone image and the occurrence of ghost, and considering the safety, availability, and electron transport capability of the material. In particular, a compound represented by the following general formula (1) is desirable. An anthraquinone derivative means a compound having an anthraquinone skeleton.
Among these, among the compounds represented by the general formula (1), a compound in which R ¹ and R ² each independently represents an alkoxy group having 1 to 10 carbon atoms is preferable.

In general formula (1), n1 and n2 each independently represent an integer of 0 or more and 3 or less. However, at least one of n1 and n2 independently represents an integer of 1 or more and 3 or less (that is, n1 and n2 do not simultaneously represent 0). m1 and m2 each independently represent an integer of 0 or 1. R ¹ and R ² each independently represents an alkyl group having 1 to 10 carbon atoms or an alkoxy group having 1 to 10 carbon atoms.

  Moreover, as an electron-accepting compound, the compound represented by following General formula (2) may be sufficient.

In general formula (2), n1, n2, n3, and n4 each independently represent an integer of 0 or more and 3 or less. m1 and m2 each independently represent an integer of 0 or 1. At least one of n1 and n2 independently represents an integer of 1 or more and 3 or less (that is, n1 and n2 do not simultaneously represent 0). At least one of n3 and n4 each independently represents an integer of 1 or more and 3 or less (that is, n3 and n4 do not simultaneously represent 0). r represents an integer of 2 or more and 10 or less. R ¹ and R ² each independently represents an alkyl group having 1 to 10 carbon atoms or an alkoxy group having 1 to 10 carbon atoms.

Here, in the general formulas (1) and (2), the alkyl group having 1 to 10 carbon atoms represented by R ¹ and R ² may be linear or branched, for example, a methyl group , Ethyl group, propyl group, isopropyl group and the like. The alkyl group having 1 to 10 carbon atoms is preferably an alkyl group having 1 to 8 carbon atoms, more preferably an alkyl group having 1 to 6 carbon atoms.
The alkoxy group (alkoxyl group) having 1 to 10 carbon atoms represented by R ¹ and R ² may be either linear or branched, for example, methoxy group, ethoxy group, propoxy group, isopropoxy group Etc. The alkoxy group having 1 to 10 carbon atoms is preferably an alkoxyl group having 1 to 8 carbon atoms, more preferably an alkoxyl group having 1 to 6 carbon atoms.

  Specific examples of the electron-accepting compound are shown below, but are not limited thereto.

The content of the electron-accepting compound is determined from the surface area and content of the metal oxide particles that are the chemical reaction or adsorption partner, and the electron transport ability of each material, but is usually 0.01% by mass or more and 20% by mass. The following range is preferable, and the range is more preferably 0.1% by mass or more and 10% by mass or less.
When the content of the electron accepting compound is 0.1% by mass or more, the effect of the electron accepting compound is easily exhibited. Further, when the content of the electron-accepting compound is 20% by mass or less, aggregation of the metal oxide particles is suppressed, and the distribution of the metal oxide particles tends to be uniform in the undercoat layer, and a good conductive path is obtained. Easy to form. Therefore, the increase in the residual potential is suppressed, and the occurrence of ghost, black spots, and non-uniform halftone density are suppressed.

-Other additives-
Other additives include resin particles. When coherent light such as a laser is used for the exposure apparatus, it is preferable to prevent moiré images. for that purpose. The surface roughness of the undercoat layer is preferably 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. Therefore, when the resin particles are added to the undercoat layer, the surface roughness can be adjusted. Examples of the resin particles include silicone resin particles and cross-linked polymethyl methacrylate (PMMA) resin.
Further, the other additives are not limited to the above, and well-known additives are also included.

-Formation of undercoat layer-
In the formation of the undercoat layer, there are surface-treated particles obtained by surface-treating the binder resin and the metal oxide particles with a silane coupling agent having an amino group, and the BET specific surface area is 10 m ² / g or more and 15 m ^2. The coating solution for forming the undercoat layer is used in which the first surface-treated particles having a BET specific surface area of 18 m ² / g or less and the second surface treated particles having a BET specific surface area of 18 m ² / g or more and 30 m ² / g or less are added to a solvent. . The coating solution for forming the undercoat layer is obtained by dispersing a premixed or predispersed electron-accepting compound and other additives in a binder resin as necessary.

  The solvent used for obtaining the coating solution for forming the undercoat layer is a known organic solvent that dissolves the above-mentioned binder resin, for example, alcohol, aromatic, halogenated hydrocarbon, ketone, ketone alcohol, ether. And ester solvents. These solvents may be used alone or in combination of two or more.

  As a method for dispersing the surface-treated particles in the coating solution for forming the undercoat layer, a known dispersion method is used. Examples thereof include a roll mill, a ball mill, a vibrating ball mill, an attritor, a sand mill, a colloid mill, and a paint shaker. A sand mill using glass beads is more preferable from the viewpoints of dispersibility and mass productivity.

  As a coating method for the coating solution for forming the undercoat layer, known coating methods such as a dip coating method, a blade coating method, a wire bar coating method, a spray coating method, a bead coating method, an air knife coating method, and a curtain coating method are used.

  The undercoat layer preferably has a Vickers hardness of 35 to 50.

  The thickness of the undercoat layer is preferably 15 μm or more, more preferably 15 μm or more and 30 μm or less, and further preferably 20 μm or more and 25 μm or less from the viewpoint of improving the graininess of the image.

(Middle layer)
Although illustration is omitted, an intermediate layer may be further provided between the undercoat layer and the photosensitive layer.
An intermediate | middle layer is a layer containing resin, for example. Examples of the resin used for the intermediate layer include an acetal resin (for example, polyvinyl butyral), polyvinyl alcohol resin, polyvinyl acetal resin, casein resin, polyamide resin, cellulose resin, gelatin, polyurethane resin, polyester resin, methacrylic resin, acrylic resin, Polymer compounds such as polyvinyl chloride resin, polyvinyl acetate resin, vinyl chloride-vinyl acetate-maleic anhydride resin, silicone resin, silicone-alkyd resin, phenol-formaldehyde resin, melamine resin, and the like can be given.
The intermediate layer may be a layer containing an organometallic compound. Examples of the organometallic compound used for the intermediate layer include organometallic compounds containing metal atoms such as zirconium, titanium, aluminum, manganese, and silicon.
The compounds used for these intermediate layers may be used alone or as a mixture or polycondensate of a plurality of compounds.

  Among these, the intermediate layer is preferably a layer containing an organometallic compound containing a zirconium atom or a silicon atom.

The formation of the intermediate layer is not particularly limited, and a well-known formation method is used. For example, a coating film of an intermediate layer forming coating solution in which the above components are added to a solvent is formed, and the coating film is dried and necessary. It is performed by heating according to.
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.

  For example, the thickness of the intermediate layer is preferably set in a range of 0.1 μm to 3 μm. An intermediate layer may be used as the undercoat layer.

(Charge generation layer)
The charge generation layer is, for example, a layer containing a charge generation material and a binder resin. The charge generation layer may be a vapor deposition layer of a charge generation material. The vapor-deposited layer of the charge generation material is suitable when an incoherent light source such as an LED (Light Emitting Diode) or an organic EL (Electro-Luminescence) image array is used.

  Examples of the charge generating material include azo pigments such as bisazo and trisazo; fused aromatic pigments such as dibromoanthanthrone; perylene pigments; pyrrolopyrrole pigments; phthalocyanine pigments; zinc oxide;

  Among these, in order to cope with near-infrared laser exposure, it is preferable to use a metal phthalocyanine pigment or a metal-free phthalocyanine pigment as the charge generation material. Specifically, for example, hydroxygallium phthalocyanine disclosed in JP-A-5-263007, JP-A-5-279591, etc .; chlorogallium phthalocyanine disclosed in JP-A-5-98181; More preferred are dichlorotin phthalocyanines disclosed in JP-A No. 140472, JP-A No. 5-140473 and the like; and titanyl phthalocyanine disclosed in JP-A No. 4-189873.

  On the other hand, in order to cope with laser exposure in the near-ultraviolet region, as the charge generation material, condensed aromatic pigments such as dibromoanthanthrone; thioindigo pigments; porphyrazine compounds; zinc oxide; trigonal selenium; Bisazo pigments and the like disclosed in 2004-78147 and JP-A-2005-181992 are preferred.

  The above-described charge generation material may also be used in the case of using an incoherent light source such as an LED having a central wavelength of light emission of 450 nm to 780 nm and an organic EL image array. However, from the viewpoint of resolution, the photosensitive layer is 20 μm or less. When the thin film is used, the electric field strength in the photosensitive layer is increased, and a charge reduction due to charge injection from the base material, so-called image defects called black spots are likely to occur. This becomes conspicuous when a charge generating material that easily generates a dark current is used in a p-type semiconductor such as trigonal selenium or a phthalocyanine pigment.

On the other hand, when an n-type semiconductor such as a condensed ring aromatic pigment, perylene pigment, azo pigment or the like is used as the charge generation material, dark current hardly occurs and even a thin film can suppress image defects called black spots. . Examples of the n-type charge generation material include compounds (CG-1) to (CG-27) described in paragraphs [0288] to [0291] of JP2012-155282A. It is not limited.
The n-type determination is performed by using a time-of-flight method that is usually used, and is determined by the polarity of the flowing photocurrent, and an n-type is more likely to flow electrons as carriers than holes.

The binder resin used for the charge generation layer is selected from a wide range of insulating resins, and the binder resin is selected from organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinyl anthracene, polyvinyl pyrene, and polysilane. You may choose.
As the binder resin, for example, polyvinyl butyral resin, polyarylate resin (polycondensate of bisphenol and aromatic divalent carboxylic acid, etc.), polycarbonate resin, polyester resin, phenoxy resin, vinyl chloride-vinyl acetate copolymer, Examples thereof include polyamide resin, acrylic resin, polyacrylamide resin, polyvinyl pyridine resin, cellulose resin, urethane resin, epoxy resin, casein, polyvinyl alcohol resin, polyvinyl pyrrolidone resin, and the like. Here, “insulating” means that the volume resistivity is 10 ¹³ Ωcm or more.
These binder resins are used singly or in combination of two or more.

  The mixing ratio of the charge generation material and the binder resin is preferably in the range of 10: 1 to 1:10 by mass ratio.

  In addition, the charge generation layer may contain a known additive.

  The formation of the charge generation layer is not particularly limited, and a known formation method is used. For example, a coating film of a charge generation layer forming coating solution in which the above components are added to a solvent is formed, and the coating film is dried. And heating as necessary. The charge generation layer may be formed by vapor deposition of a charge generation material. Formation of the charge generation layer by vapor deposition is particularly suitable when a condensed ring aromatic pigment or perylene pigment is used as the charge generation material.

  Solvents for preparing the charge generation layer forming coating solution include methanol, ethanol, n-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, n-acetate. -Butyl, dioxane, tetrahydrofuran, methylene chloride, chloroform, chlorobenzene, toluene and the like. These solvents are used alone or in combination of two or more.

Examples of a method for dispersing particles (for example, a charge generation material) in a coating solution for forming a charge generation layer include, for example, a media disperser such as a ball mill, a vibrating ball mill, an attritor, a sand mill, a horizontal sand mill, a stirring, an ultrasonic disperser, etc. Medialess dispersers such as roll mills and high-pressure homogenizers are used. Examples of the high-pressure homogenizer include a collision method in which a 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.
In this dispersion, it is effective that the average particle size of the charge generation material in the coating solution for forming the charge generation layer is 0.5 μm or less, preferably 0.3 μm or less, more preferably 0.15 μm or less. .

  Examples of methods for applying the charge generation layer forming coating solution on the undercoat layer (or on the intermediate layer) include blade coating, wire bar coating, spray coating, dip coating, bead coating, and air knife coating. And usual methods such as a curtain coating method.

  The film thickness of the charge generation layer is, for example, preferably set in the range of 0.1 μm to 5.0 μm, more preferably 0.2 μm to 2.0 μm.

(Charge transport layer)
The charge transport layer is, for example, a layer containing a charge transport material and a binder resin. The charge transport layer may be a layer containing a polymer charge transport material.

  Examples of charge transport materials include quinone compounds such as p-benzoquinone, chloranil, bromanyl and anthraquinone; tetracyanoquinodimethane compounds; fluorenone compounds such as 2,4,7-trinitrofluorenone; xanthone compounds; benzophenone compounds A cyanovinyl compound; an electron transporting compound such as an ethylene compound; Examples of the charge transporting material include hole transporting compounds such as triarylamine compounds, benzidine compounds, arylalkane compounds, aryl-substituted ethylene compounds, stilbene compounds, anthracene compounds, and hydrazone compounds. These charge transport materials may be used alone or in combination of two or more, but are not limited thereto.

  As the charge transport material, from the viewpoint of charge mobility, a triarylamine derivative represented by the following structural formula (a-1) and a benzidine derivative represented by the following structural formula (a-2) are preferable.

In Structural Formula (a-1), Ar ^T1 , Ar ^T2 , and Ar ^T3 are each independently a substituted or unsubstituted aryl group, —C ₆ H ₄ —C (R ^T4 ) ═C (R ^T5 ) (R ^T6), or _{-C 6 H 4 -CH = CH-} CH = C (R T7) shows the ^{(R T8).} R ^T4 , R ^T5 , R ^T6 , R ^T7 , and R ^T8 each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group.
Examples of the substituent for each group include a halogen atom, an alkyl group having 1 to 5 carbon atoms, and an alkoxy group having 1 to 5 carbon atoms. Examples of the substituent of each group also include a substituted amino group substituted with an alkyl group having 1 to 3 carbon atoms.

In Structural Formula (a-2), R ^T91 and R ^T92 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 ^T101 , R ^T102 , R ^T111 and R ^T112 are each independently ^substituted with 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. A substituted amino group, a substituted or unsubstituted aryl group, —C (R ^T12 ) ═C (R ^T13 ) (R ^T14 ), or —CH═CH— ^CH═C (R ^T15 ) (R ^T16 ), R ^T12 , R ^T13 , R ^T14 , R ^T15 and R ^T16 each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group. Tm1, Tm2, Tn1, and Tn2 each independently represent an integer of 0 or more and 2 or less.
Examples of the substituent for each group include a halogen atom, an alkyl group having 1 to 5 carbon atoms, and an alkoxy group having 1 to 5 carbon atoms. Examples of the substituent of each group also include a substituted amino group substituted with an alkyl group having 1 to 3 carbon atoms.

Here, among the triarylamine derivative represented by the structural formula (a-1) and the benzidine derivative represented by the structural formula (a-2), in particular, “—C ₆ H ₄ —CH═CH—CH═ Triarylamine derivatives having “C (R ^T7 ) (R ^T8 )” and benzidine derivatives having “—CH═CH— ^CH═C (R ^T15 ) (R ^T16 )” are preferable from the viewpoint of charge mobility.

  As the polymer charge transporting material, known materials having charge transporting properties such as poly-N-vinylcarbazole and polysilane are used. In particular, polyester-based polymer charge transport materials disclosed in JP-A-8-176293, JP-A-8-208820 and the like are particularly preferable. The polymer charge transport material may be used alone or in combination with a binder resin.

The binder resin used for the charge transport layer is polycarbonate resin, polyester resin, polyarylate resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinylidene chloride resin, polystyrene resin, polyvinyl acetate resin, styrene-butadiene copolymer, Vinylidene chloride-acrylonitrile copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicone resin, silicone alkyd resin, phenol-formaldehyde resin, styrene-alkyd resin, poly-N -Vinylcarbazole, polysilane, etc. are mentioned. Among these, as the binder resin, a polycarbonate resin or a polyarylate resin is preferable. These binder resins are used alone or in combination of two or more.
The mixing ratio of the charge transport material and the binder resin is preferably 10: 1 to 1: 5 by mass ratio.

  In addition, the charge transport layer may contain a known additive.

  The formation of the charge transport layer is not particularly limited, and a known formation method is used. For example, a coating film of a charge transport layer forming coating solution in which the above components are added to a solvent is formed, and the coating film is dried. This is done by heating as necessary.

  Solvents for preparing the coating solution for forming the charge transport layer include aromatic hydrocarbons such as benzene, toluene, xylene and chlorobenzene; ketones such as acetone and 2-butanone; methylene chloride, chloroform and ethylene chloride. Halogenated aliphatic hydrocarbons: Usual organic solvents such as cyclic or linear ethers such as tetrahydrofuran and ethyl ether. These solvents are used alone or in combination of two or more.

  Coating methods for applying the charge transport layer forming coating solution on the charge generation layer include blade coating method, wire bar coating method, spray coating method, dip coating method, bead coating method, air knife coating method, curtain A usual method such as a coating method may be mentioned.

  The thickness of the charge transport layer is, for example, preferably set in the range of 5 μm to 50 μm, more preferably 10 μm to 30 μm.

(Protective layer)
The protective layer is provided on the photosensitive layer as necessary. The protective layer is provided, for example, for the purpose of preventing chemical change of the photosensitive layer during charging or further improving the mechanical strength of the photosensitive layer.
Therefore, it is preferable to apply a layer composed of a cured film (crosslinked film) as the protective layer. Examples of these layers include the layers shown in 1) or 2) below.

1) A layer composed of a cured film of a composition containing a reactive group-containing charge transporting material having a reactive group and a charge transporting skeleton in the same molecule (that is, a polymer or cross-linking of the reactive group-containing charge transporting material) Layer containing body)
2) a layer composed of a cured film of a composition comprising a non-reactive charge transport material and a reactive group-containing non-charge transport material having a reactive group and having no charge transport skeleton (that is, A layer comprising a non-reactive charge transport material and a polymer or a cross-linked product of the reactive group-containing non-charge transport material)

The reactive group of the reactive group-containing charge transport material includes a chain polymerizable group, an epoxy group, —OH, —OR [wherein R represents an alkyl group], —NH ₂ , —SH, —COOH, —SiR. ^Q1 _3-Qn (OR ^Q2 ) _Qn [wherein R ^Q1 represents a hydrogen atom, an alkyl group, or a substituted or unsubstituted aryl group, and R ^Q2 represents a hydrogen atom, an alkyl group, or a trialkylsilyl group. Qn represents an integer of 1 to 3], and the like, and other well-known reactive groups.

  The chain polymerizable group is not particularly limited as long as it is a functional group capable of radical polymerization. For example, it is a functional group having a group containing at least a carbon double bond. Specific examples include groups containing at least one selected from a vinyl group, vinyl ether group, vinyl thioether group, styryl group, acryloyl group, methacryloyl group, and derivatives thereof. Among them, the chain polymerizable group is preferably a group containing at least one selected from a vinyl group, a styryl group, an acryloyl group, a methacryloyl group, and derivatives thereof because of its excellent reactivity. .

  The charge transporting skeleton of the reactive group-containing charge transporting material is not particularly limited as long as it is a known structure in an electrophotographic photoreceptor, and examples thereof include triarylamine compounds, benzidine compounds, hydrazone compounds, and the like. And a structure conjugated from a nitrogen-containing hole transporting compound and conjugated with a nitrogen atom. Among these, a triarylamine skeleton is preferable.

  The reactive group-containing charge transport material having a reactive group and a charge transport skeleton, a non-reactive charge transport material, and a reactive group-containing non-charge transport material may be selected from well-known materials.

  In addition, the protective layer may contain known additives.

  The formation of the protective layer is not particularly limited, and a known formation method is used.For example, a coating film of a coating liquid for forming a protective layer in which the above components are added to a solvent is formed, and the coating film is dried. It is performed by performing a curing process such as heating as necessary.

Solvents for preparing the coating solution for forming the protective layer include aromatic solvents such as toluene and xylene; ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; ester solvents such as ethyl acetate and butyl acetate; tetrahydrofuran And ether solvents such as dioxane; cellosolv solvents such as ethylene glycol monomethyl ether; alcohol solvents such as isopropyl alcohol and butanol. These solvents are used alone or in combination of two or more.
The protective layer forming coating solution may be a solventless coating solution.

  As a method for applying the coating solution for forming the protective layer on the photosensitive layer (for example, charge transport layer), dip coating method, push-up coating method, wire bar coating method, spray coating method, blade coating method, knife coating method, curtain coating method. Ordinary methods such as a method may be mentioned.

  The thickness of the protective layer is, for example, preferably set in the range of 1 μm to 20 μm, more preferably 2 μm to 10 μm.

(Single layer type photosensitive layer)
The single-layer type photosensitive layer (charge generation / charge transport layer) is, for example, a layer containing a charge generation material, a charge transport material, and, if necessary, a binder resin and other known additives. Note that these materials are the same as those described for the charge generation layer and the charge transport layer.
In the single-layer type photosensitive layer, the content of the charge generating material is preferably 10% by mass or more and 85% by mass or less, and preferably 20% by mass or more and 50% by mass or less with respect to the total solid content. In the single-layer type photosensitive layer, the content of the charge transport material is preferably 5% by mass or more and 50% by mass or less based on the total solid content.
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 film thickness of the single-layer type photosensitive layer is, for example, from 5 μm to 50 μm, and preferably from 10 μm to 40 μm.

(Other)
In the electrophotographic photosensitive member according to the exemplary embodiment, the photosensitive layer and the protective layer are formed in the photosensitive layer for the purpose of preventing deterioration of the photosensitive member due to ozone, oxidizing gas, or light / heat generated in the image forming apparatus. Additives such as antioxidants, light stabilizers, heat stabilizers and the like may be added.
Further, at least one electron accepting substance may be added to the photosensitive layer and the protective layer for the purpose of improving sensitivity, reducing residual potential, and reducing fatigue during repeated use.
Further, in the photosensitive layer and the protective layer, silicone oil may be added as a leveling agent to the coating solution for forming each layer to improve the smoothness of the coating film.

[Image forming apparatus (and process cartridge)]
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 electrostatic latent image formation that forms an electrostatic latent image on the surface of the charged electrophotographic photosensitive member. Means, developing means for developing the electrostatic latent image formed on the surface of the electrophotographic photosensitive member with a developer containing toner to form a toner image, and transfer means for transferring the toner image to the surface of the recording medium; Is provided. The electrophotographic photosensitive member according to the present embodiment is applied as the electrophotographic photosensitive member.

  The image forming apparatus according to the present embodiment includes an apparatus having fixing means for fixing a toner image transferred to the surface of a recording medium; direct transfer for directly transferring the toner image formed on the surface of the electrophotographic photosensitive member to the recording medium Type apparatus; intermediate transfer in which the toner image formed on the surface of the electrophotographic photosensitive member is primarily transferred onto the surface of the intermediate transfer member, and the toner image transferred onto the surface of the intermediate transfer member is secondarily transferred onto the surface of the recording medium. Type apparatus; apparatus provided with cleaning means for cleaning the surface of the electrophotographic photosensitive member after the toner image is transferred and before charging; after the toner image is transferred, the surface of the image carrier is irradiated with a charge-removing light before charging. A known image forming apparatus, such as an apparatus provided with a static elimination means for removing electricity; an apparatus provided with an electrophotographic photosensitive member heating member for increasing the temperature of the electrophotographic photosensitive member and reducing the relative temperature is applied.

  In the case of an intermediate transfer type apparatus, the transfer means includes, for example, an intermediate transfer body on which a toner image is transferred onto the surface, and a primary transfer that primarily transfers the toner image formed on the surface of the image holding body onto the surface of the intermediate transfer body. And a secondary transfer unit that secondarily transfers the toner image transferred onto the surface of the intermediate transfer member onto the surface of the recording medium.

  The image forming apparatus according to the present embodiment may be either a dry developing type image forming apparatus or a wet developing type (developing type using a liquid developer).

  Note that in the image forming apparatus according to the present embodiment, for example, the portion including the electrophotographic photosensitive member may have a cartridge structure (process cartridge) that is detachable from the image forming apparatus. As the process cartridge, for example, a process cartridge including the electrophotographic photosensitive member according to this embodiment is preferably used. In addition to the electrophotographic photosensitive member, the process cartridge may include at least one selected from the group consisting of a charging unit, an electrostatic latent image forming unit, a developing unit, and a transfer unit.

  Hereinafter, an example of the image forming apparatus according to the present embodiment will be described, but the present invention is not limited thereto. In addition, the main part shown to a figure is demonstrated and the description is abbreviate | omitted about others.

FIG. 7 is a schematic configuration diagram illustrating an example of an image forming apparatus according to the present embodiment.
As shown in FIG. 7, the image forming apparatus 100 according to this embodiment includes a process cartridge 300 including an electrophotographic photosensitive member 7, an exposure device 9 (an example of an electrostatic latent image forming unit), and a transfer device 40 (primary. Transfer device) and an intermediate transfer member 50. In the image forming apparatus 100, the exposure device 9 is disposed at a position where the electrophotographic photosensitive member 7 can be exposed from the opening of the process cartridge 300, and the transfer device 40 is interposed between the electrophotographic photosensitive member via the intermediate transfer member 50. 7, and a part of the intermediate transfer member 50 is disposed in contact with the electrophotographic photosensitive member 7. Although not shown, it also has a secondary transfer device that transfers the toner image transferred to the intermediate transfer member 50 to a recording medium (for example, paper). The intermediate transfer member 50, the transfer device 40 (primary transfer device), and the secondary transfer device (not shown) correspond to an example of a transfer unit.

  In the process cartridge 300 in FIG. 7, an electrophotographic photosensitive member 7, a charging device 8 (an example of a charging unit), a developing device 11 (an example of a developing unit), and a cleaning device 13 (an example of a cleaning unit) are integrated in a housing. I support it. The cleaning device 13 includes a cleaning blade (an example of a cleaning member) 131, and the cleaning blade 131 is disposed so as to contact the surface of the electrophotographic photosensitive member 7. The cleaning member may be a conductive or insulating fibrous member instead of the cleaning blade 131, and may be used alone or in combination with the cleaning blade 131.

  In FIG. 7, as an image forming apparatus, a fibrous member 132 (roll shape) for supplying the lubricant 14 to the surface of the electrophotographic photosensitive member 7 and a fibrous member 133 (flat brush shape) for assisting cleaning are shown. Examples are provided, but these are arranged as necessary.

  Hereinafter, each configuration of the image forming apparatus according to the present embodiment will be described.

-Charging device-
As the charging device 8, for example, a contact type charger using a conductive or semiconductive charging roller, a charging brush, a charging film, a charging rubber blade, a charging tube or the like is used. Further, a non-contact type roller charger, a known charger such as a scorotron charger using a corona discharge or a corotron charger may be used.

-Exposure device-
Examples of the exposure device 9 include optical system devices that expose the surface of the electrophotographic photoreceptor 7 with light such as semiconductor laser light, LED light, and liquid crystal shutter light in a predetermined image-like manner. The wavelength of the light source is set within the spectral sensitivity region of the electrophotographic photosensitive member. As the wavelength of the semiconductor laser, near infrared having an oscillation wavelength near 780 nm is the mainstream. However, the present invention is not limited to this wavelength, and an oscillation wavelength laser in the 600 nm range or a laser having an oscillation wavelength of 400 nm to 450 nm as a blue laser may be used. In addition, a surface-emitting type laser light source that can output a multi-beam is also effective for color image formation.

-Developer-
Examples of the developing device 11 include a general developing device that performs development by bringing a developer into contact or non-contact with the developer. The developing device 11 is not particularly limited as long as it has the functions described above, and is selected according to the purpose. For example, a known developing device having a function of attaching a one-component developer or a two-component developer to the electrophotographic photosensitive member 7 using a brush, a roller, or the like can be used. Among these, those using a developing roller holding the developer on the surface are preferable.

  The developer used in the developing device 11 may be a one-component developer including a toner alone or a two-component developer including a toner and a carrier. Further, the developer may be magnetic or non-magnetic. A well-known thing is applied for these developers.

-Cleaning device-
As the cleaning device 13, a cleaning blade type device including a cleaning blade 131 is used.
In addition to the cleaning blade method, a fur brush cleaning method and a simultaneous development cleaning method may be employed.

-Transfer device-
As the transfer device 40, for example, a contact transfer charger using a belt, a roller, a film, a rubber blade, etc., or a known transfer charger such as a scorotron transfer charger using a corona discharge or a corotron transfer charger. Can be mentioned.

-Intermediate transfer member-
As the intermediate transfer member 50, a belt-like member (intermediate transfer belt) containing polyimide, polyamideimide, polycarbonate, polyarylate, polyester, rubber or the like having semiconductivity is used. Further, as the form of the intermediate transfer member, a drum-like member may be used in addition to the belt-like member.

FIG. 8 is a schematic configuration diagram illustrating another example of the image forming apparatus according to the present embodiment.
An image forming apparatus 120 shown in FIG. 8 is a tandem multicolor image forming apparatus equipped with four process cartridges 300. In the image forming apparatus 120, four process cartridges 300 are arranged in parallel on the intermediate transfer member 50, and one electrophotographic photosensitive member is used for one color. The image forming apparatus 120 has the same configuration as that of the image forming apparatus 100 except that it is a tandem system.

  Next, the operation of the image forming apparatus 100 according to the present embodiment will be described. First, at the same time as the electrophotographic photosensitive member 7 rotates, it is negatively charged by the charging device 8.

  The electrophotographic photosensitive member 7 whose surface is negatively charged by the charging device 8 is exposed by the exposure device 10 to form an electrostatic latent image on the surface.

  When the portion where the electrostatic latent image is formed on the electrophotographic photosensitive member 7 approaches the developing device 11, the developing device 11 attaches toner to the electrostatic latent image and forms a toner image.

The electrophotographic photosensitive member 7 on which the toner image is formed further rotates, and the toner image is primarily transferred to the intermediate transfer member 50 by the transfer device 40 and then secondarily transferred to a recording sheet (not shown). Thereby, a toner image is formed on the recording paper.
After the primary transfer, the toner remaining on the electrophotographic photoreceptor 7 is removed by the cleaning device 13.

  The toner image is fixed on the recording paper on which the toner image is formed by a fixing device (not shown).

  Note that the toner image formed on the surface of the photoconductor 7 without using the intermediate transfer body 50 may be directly transferred to the recording paper.

  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.

<Preparation of surface-treated metal oxide particles (surface-treated particles)>
[Surface treatment example 1]
100 parts by mass of zinc oxide (trade name: MZ-300, manufactured by Teika) as metal oxide particles, and 10% by mass toluene solution of N-β (aminoethyl) -γ-aminopropyltrimethoxysilane as a silane coupling agent 5 parts by mass and 195 parts by mass of toluene were mixed and stirred, and refluxed for 2 hours. Thereafter, toluene was distilled off under reduced pressure at 10 mmHg, followed by baking at 135 ° C. for 2 hours to obtain surface-treated particles.

It was 29 m < ² > / g when it measured by the nitrogen substitution method about the BET specific surface area of the obtained surface treatment particle | grains using the BET type specific surface area measuring device (Shimadzu Corporation make: Flow soap II2300).

[Surface treatment examples 2 to 15]
As shown in Table 1 below, surface-treated metal oxide particles (surface-treated particles) were prepared in the same manner as in Surface Treatment Example 1 except that the metal oxide particles and the surface-treating agent (silane coupling agent) were changed. did.
In addition, the metal oxide particles used in each surface treatment example shown in Table 1 are as follows.
・ Zinc oxide 1: manufactured by Teika Co., Ltd., trade name: MZ-300
-Zinc oxide 2: manufactured by Teika Co., Ltd., trade name: MZ-150
-Zinc oxide 3: manufactured by Teika Co., Ltd., trade name: MZ-200
-Zinc oxide 4: manufactured by Teika Co., Ltd., trade name: MZ-500
・ Zinc oxide 5: manufactured by Teika Co., Ltd., trade name: MZ-100
・ Zinc oxide 6: Made by Teika Co., Ltd.
・ Zinc oxide 7: Made by Teika Co., Ltd., Product name: Special order product-2
・ Titanium oxide 1: manufactured by Teika Co., Ltd., trade name: MT-700B
-Titanium oxide 2: manufactured by Teika Co., Ltd., trade name: MT-500B

[Example 1]
Zinc oxide particles surface-treated in surface treatment example 1: 10 parts by mass and zinc oxide surface-treated in surface treatment example 4: 10 parts by mass, blocked isocyanate Sumijoule 3175 (manufactured by Sumitomo Bayern Urethane Co., Ltd.): 5 parts by mass In addition, 0.08 parts by mass of the electron-accepting compound “1-2” and 25 parts by mass of methyl ethyl ketone are mixed for 30 minutes, and then 5 parts by mass of butyral resin ESREC BM-1 (manufactured by Sekisui Chemical Co., Ltd.) is added. Then, dispersion was performed for 1 hour in a sand mill to obtain a dispersion.
Furthermore, 3 parts by mass of silicone resin particles Tospearl 130 (manufactured by Toshiba Silicone) were added and stirred for a time to obtain a coating solution.
Furthermore, the coating solution was 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, followed by drying and curing at 180 ° C. for 30 minutes to obtain an undercoat layer having a thickness of 19 μm. .

  Next, hydroxygallium phthalocyanine is used as a charge generation material, from 15 parts by mass thereof, from 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. The resulting mixture was dispersed in a sand mill for 4 hours. The obtained dispersion was dip-coated on the intermediate layer and dried at 100 ° C. for 10 minutes to form a charge generation layer having a thickness of 0.2 μm.

  In addition, 4 parts by mass of N, N′-diphenyl-N, N′-bis (3-methylphenyl)-[1,1 ′] biphenyl-4,4′-diamine and bisphenol Z polycarbonate resin (molecular weight 40,000) A coating solution prepared by dissolving 6 parts by mass with 25 parts by mass of tetrahydrofuran and 5 parts by mass of chlorobenzene was applied on the charge generation layer and dried at 130 ° C. for 40 minutes to obtain a film thickness of 35 μm. The charge transport layer was formed. As a result, a photoreceptor of Example 1 was obtained.

(Image quality evaluation)
The photoconductor obtained as described above is mounted on a copying machine “Docu Center Color 500” manufactured by Fuji Xerox Co., Ltd., and the chart shown in FIG. 9 is fed in A4 side feed (short side feed) at 30 ° C./80% RH. ) And 100,000 sheets were output continuously. The chart shown in FIG. 9 is a chart in which an area having a white letter “G” and a halftone image area having an image density of 40% are printed in a black solid image having an image density of 100%.

-Ghost evaluation-
The first image output (initial image) and the 100,000 output image (100,000 output image) were visually confirmed by confirming the change in G-shaped density. The evaluation criteria are as follows.
A: No change in density B: Some change in density and no problem in actual use C: Change in density cannot withstand actual use

-Halftone image density unevenness evaluation-
The evaluation of the halftone image density unevenness is random in the region of the halftone image having an image density of 40% with respect to the first output image (initial image) and the 100,000 output image (100,000 output image). The density change was made visually.
The evaluation criteria are as follows.
A: No change in density B: Some change in density and no problem in actual use C: Change in density cannot withstand actual use

-Graininess evaluation-
Graininess was evaluated by visual observation of fine density unevenness in the 40% halftone image output on the first sheet.
A: No problem B: There is a slight problem in actual use C: Unbearable in actual use

[Examples 2 to 6]
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the surface-treated particles were changed as shown in Table 2 below, and the same evaluation was performed.

[Example 7]
An electrophotographic photoreceptor was prepared in the same manner as in Example 1 except that the thickness of the undercoat layer was changed to 14 μm, and the same evaluation was performed.

[Example 8]
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the titanium oxide shown in Table 1 was used, and the same evaluation was performed.

[Example 9]
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the silane coupling agent shown in Table 1 was used, and the same evaluation was performed.

[Example 10]
An electrophotographic photoreceptor was prepared in the same manner as in Example 1 except that the electron accepting compound “1-21” was used as the electron accepting compound, and the same evaluation was performed.

[Example 11]
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the surface-treated particles were changed as shown in Table 2 below, and the same evaluation was performed.

[Comparative Examples 1 to 7]
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the surface-treated particles contained in the undercoat layer were changed as shown in Table 2 below, and the same evaluation was performed.

  Table 2 shows the composition of the surface-treated particles contained in the undercoat layer of the electrophotographic photosensitive member produced in each example. In addition, the total content of the surface-treated particles in the undercoat layer in each example other than Example 1 is the same as that in Example 1, and the “content ratio” is the amount of each surface-treated particle relative to the content of the entire surface-treated particles. It is a content ratio.

  Table 3 shows the evaluation results of Examples and Comparative Examples.

  From the above results, it can be seen that in this example, the occurrence of ghost and halftone image density unevenness was suppressed for the image after the initial and long-term (100,000 sheets) output as compared with the comparative example.

DESCRIPTION OF SYMBOLS 1 Conductive base material, 2 Undercoat layer, 3 Photosensitive layer, 4 Intermediate layer, 5 Protective layer, 7 Electrophotographic photosensitive member, 8 Charging apparatus, 9 Exposure apparatus, 11 Developing apparatus, 13 Cleaning apparatus, 14 Lubricant, 31 Charge generation layer, 32 Charge transport layer, 40 Transfer device, 50 Intermediate transfer member, 100 Image forming device, 120 Image forming device, 300 Process cartridge

Claims (12)

A conductive substrate;
Wherein disposed on the conductive substrate on the binder resin, and, as the surface treated particles surface-treated with a silane coupling agent having an amino group metal oxide particles, BET specific surface area of 10 m 2 / ^g or more 15 m ² / an undercoat layer comprising first surface-treated particles that are not more than g and second surface-treated particles that have a BET specific surface area of not less than 18 m ² / g and not more than 30 m ² / g;
A photosensitive layer disposed on the undercoat layer;
An electrophotographic photosensitive member having:   The electrophotographic photosensitive member according to claim 1, wherein the metal oxide particles are at least one selected from the group consisting of tin oxide, titanium oxide, and zinc oxide.   The first surface-treated particles and the second surface-treated particles each have a surface treatment amount of the amino group-containing silane coupling agent with respect to the metal oxide particles of 0.05% by mass to 1.5% by mass. The electrophotographic photosensitive member according to claim 1, which is   The electrophotographic photosensitive member according to claim 1, wherein the undercoat layer further contains an electron accepting compound.   The electrophotographic photoreceptor according to claim 4, wherein the electron-accepting compound is an anthraquinone derivative. The electrophotographic photoreceptor according to claim 5, wherein the anthraquinone derivative is represented by the following general formula (1).


(In general formula (1), n1 and n2 each independently represent an integer of 0 or more and 3 or less, provided that at least one of n1 and n2 independently represents an integer of 1 or more and 3 or less. M1 and m2 Each independently represents an integer of 0 or 1. R ¹ and R ² each independently represents an alkyl group having 1 to 10 carbon atoms or an alkoxy group having 1 to 10 carbon atoms.   The electrophotographic photoreceptor according to claim 1, wherein the undercoat layer has a thickness of 15 μm or more and 30 μm or less.   The electrophotographic photosensitive member according to any one of claims 1 to 7, wherein a content of the second surface-treated particles in the undercoat layer is larger than a content of the first surface-treated particles. The electrophotographic photosensitive member according to any one of claims 1 to 8,
A process cartridge that can be attached to and detached from an image forming apparatus.   The process cartridge according to claim 9, further comprising a contact charging type charging unit that contacts the electrophotographic photosensitive member to charge the surface of the electrophotographic photosensitive member. The electrophotographic photosensitive member according to any one of claims 1 to 8,
Charging means for charging the surface of the electrophotographic photosensitive member;
An electrostatic latent image forming means for forming an electrostatic latent image on the surface of the charged electrophotographic photosensitive member;
Developing means for developing the electrostatic latent image formed on the surface of the electrophotographic photosensitive member with a developer containing toner to form a toner image;
Transfer means for transferring the toner image to the surface of the recording medium;
An image forming apparatus comprising:   The image forming apparatus according to claim 11, wherein the charging unit is a contact charging type charging unit.