JP2014191103A - Electrophotographic photoreceptor, image forming apparatus, and process cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor that suppresses unevenness in image density, and suppresses a reduction in density after repeated image formation.SOLUTION: An electrophotographic photoreceptor 1 includes: a conductive support 2; an undercoat layer 4 that is arranged on the conductive support, contains an electron receptive compound including metal oxide particles and an anthraquinone structure and a binder resin crosslinked by a block-type isocyanate compound blocked by methyl ethyl ketone oxime, where a content of the electron receptive compound having an anthraquinone structure is 0.7 pt.mass or more based on 100 pts.mass of the metal oxide particles and a content of the methyl ethyl ketone oxime in the undercoat layer is 0.2 mass% or less; and a photosensitive layer 3 that is arranged on the undercoat layer.

Description

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

  In recent years, electrophotographic image formation has been widely used in image forming apparatuses such as copying machines and laser printers. An organic photosensitive material is mainly used for the photosensitive layer of the electrophotographic photosensitive member used in the image forming apparatus. Specifically, in addition to an organic photoreceptor having a function-integrated type photosensitive layer including a material having a charge generation function (charge generation material) and a material having a charge transport function (charge transport material), a charge including a charge generation material is included. An organic photoreceptor having a function-separated type photosensitive layer in which a generation layer and a charge transport layer containing a charge transport material are sequentially laminated has been put into practical use.

  An electrophotographic photoreceptor is produced by forming a photosensitive layer on the surface of a conductive support. Generally, the electrophotographic photoreceptor is improved in coating property of the photosensitive layer, the support surface is protected, and defects on the support are covered. In order to protect the photosensitive layer from electrical breakdown and improve the carrier injection property of the photosensitive layer, a subbing layer having no photosensitivity or a layer called an intermediate layer is interposed.

  For example, Patent Document 1 includes an intermediate layer between a conductive support and a photosensitive layer, and the intermediate layer is an active hydrogen capable of reacting with a blocked isocyanate compound and an isocyanate group in the blocked isocyanate compound. A single layer containing a charge generating material and a charge transporting material, wherein the photosensitive layer is a layer formed by thermal curing from an intermediate layer coating solution containing a polyol-based resin having a containing group and an aqueous medium. Type photosensitive layer, or a layered photosensitive layer in which a charge generation layer containing a charge generation material and a charge transport layer containing a charge transport material are laminated in this order or in reverse order, and the charge transport material is a specific type An electrophotographic photoreceptor characterized by being a benzofuranamine-diene or triene compound is disclosed.

  Patent Document 2 has at least an intermediate layer and a photosensitive layer in this order on a conductive support, and the intermediate layer can react with at least an aqueous blocked isocyanate compound and an isocyanate group on the conductive support. Obtained by applying an intermediate layer-forming coating solution obtained by dissolving or dispersing an aqueous resin having two or more active hydrogen-containing groups in an aqueous medium and then thermally curing the photosensitive layer as a charge transport material. An electrophotographic photoreceptor comprising a specific N, N′-bisenamine compound is disclosed.

  Patent Document 3 discloses an electrophotographic photosensitive member, a charging unit for charging the electrophotographic photosensitive member, an exposure unit for exposing the charged electrophotographic photosensitive member to form an electrostatic latent image, and an exposure unit. Developing means for developing the electrostatic latent image formed thereon to form a toner image; transfer means for transferring the toner image formed by development onto a recording material; and transferring the transferred toner image onto the recording material Fixing means for forming an image by fixing the toner, cleaning means for removing and collecting the toner remaining on the electrophotographic photosensitive member, and static elimination means for neutralizing surface charge remaining on the electrophotographic photosensitive member, The electrophotographic photoreceptor has a blocked isocyanate compound and an active hydrogen-containing group capable of reacting with an isocyanate group in the blocked isocyanate compound between the conductive support and the photosensitive layer. An intermediate in which the isocyanate group is present in the blocked isocyanate compound at a molar ratio of 0.5 to 1.5 with respect to the active hydrogen-containing group. It has an intermediate layer formed by thermal curing from a layer coating solution, and the charging means is a contact charging method in which charging is performed by bringing a charging member into contact with the electrophotographic photosensitive member. An image forming apparatus is disclosed.

JP 2011-118299 A JP 2010-271652 A JP 2010-256694 A

  SUMMARY OF THE INVENTION An object of the present invention is to provide an electrophotographic photosensitive member in which unevenness in image density is suppressed and reduction in density when an image is repeatedly formed is suppressed.

The above object is achieved by the present invention described below.
The invention of claim 1 is a conductive support and an undercoat layer disposed on the conductive support, and is blocked by metal oxide particles, an electron-accepting compound having an anthraquinone structure, and methyl ethyl ketone oxime. A binder resin cross-linked by the blocked isocyanate compound, the content of the electron-accepting compound having the anthraquinone structure with respect to 100 parts by mass of the metal oxide particles is 0.7 parts by mass or more, and An electrophotographic photosensitive member comprising: an undercoat layer having a methyl ethyl ketone oxime content of 0.2% by mass or less in the undercoat layer; and a photosensitive layer disposed on the undercoat layer.
The invention according to claim 2 is the electrophotographic photoreceptor according to claim 1, wherein the electron-accepting compound having an anthraquinone structure is an electron-accepting compound having a hydroxyanthraquinone structure.
According to a third aspect of the present invention, there is provided an electrophotographic photosensitive member according to the first or second aspect, a charging device for charging the electrophotographic photosensitive member, and an electrostatic latent image formed on the surface of the charged electrophotographic photosensitive member. An electrostatic latent image forming device to be formed; a developing device for developing the electrostatic latent image formed on the surface of the electrophotographic photosensitive member with toner to form a toner image; and a surface formed on the surface of the electrophotographic photosensitive member. And a transfer device that transfers the toner image onto a recording medium.
According to a fourth aspect of the present invention, there is provided a process cartridge that includes at least the electrophotographic photosensitive member according to the first or second aspect and is detachable from the image forming apparatus.

  According to the invention of claim 1, image density unevenness is suppressed as compared with the case where the content of the electron-accepting compound having an anthraquinone structure and the content of methyl ethyl ketone oxime contained in the undercoat layer are not included in the above ranges, respectively. In addition, an electrophotographic photosensitive member is provided in which rapid density reduction is suppressed when repeated image formation is performed.

  According to the second aspect of the present invention, compared to the case where the electron-accepting compound having an anthraquinone structure contained in the undercoat layer is not an electron-accepting compound having a hydroxyanthraquinone structure, a decrease in density when images are formed repeatedly is suppressed. An electrophotographic photoreceptor is provided.

  According to the inventions of claims 3 and 4, when an electrophotographic photosensitive member in which the content of the electron-accepting compound having an anthraquinone structure contained in the undercoat layer and the content of methyl ethyl ketone oxime are not included in the above ranges is applied. Compared to the above, there are provided an image forming apparatus and a process cartridge in which unevenness of image density is suppressed and density reduction is suppressed when repeated image formation is performed.

It is the schematic which shows the cross section of a part of the electrophotographic photoreceptor which concerns on this embodiment. 1 is a schematic diagram illustrating a basic configuration of an image forming apparatus according to a first embodiment. It is the schematic which shows the basic composition of the image forming apparatus of 2nd Embodiment. It is the schematic which shows the basic composition of an example of a process cartridge.

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

<Electrophotographic photoreceptor>
The electrophotographic photoreceptor according to the exemplary embodiment is a conductive support and an undercoat layer disposed on the conductive support, and includes metal oxide particles, an electron-accepting compound having an anthraquinone structure, and The content of the electron-accepting compound having the anthraquinone structure with respect to 100 parts by mass of the metal oxide particles is 0.7 parts by mass or more, including a binder resin crosslinked with a blocked isocyanate compound blocked with methyl ethyl ketone oxime. And an undercoat layer in which the content of the methyl ethyl ketone oxime in the undercoat layer is 0.2% by mass or less, and a photosensitive layer disposed on the undercoat layer.
With such a configuration, image density unevenness is suppressed, and density reduction when images are repeatedly formed is suppressed. The reason is not clear, but is presumed as follows.

Electrophotographic photoreceptors are required to have potential stability in addition to wear resistance.
When the electrophotographic photoreceptor is provided with an undercoat layer between, for example, a conductive base material and a photosensitive layer, a blocking function is obtained by dispersing metal oxide particles surface-treated with a coupling agent or the like in the undercoat layer. And the resistance adjustment function is adjusted. However, when charging, exposure, and static elimination are repeated continuously, the base material is oxidized mainly due to the silane coupling agent of the metal oxide particles contained in the undercoat layer, and the residual potential increases due to the increase in resistance. It may occur. In order to suppress such an increase in residual potential, it is conceivable to add an electron-accepting compound having an anthraquinone structure for the purpose of preventing oxidation. The effect of extending the potential stability is expected by increasing the amount of the electron-accepting compound having an anthraquinone structure.

  On the other hand, a certain amount or more of an electron-accepting compound is added, and a block type isocyanate (hereinafter referred to as “MEK”) using methyl ethyl ketone oxime (hereinafter sometimes referred to as “MEK oxime”) as a blocking agent as a crosslinking agent for the binder resin. It has been found that when the oxime block type isocyanate compound is sometimes used, the MEK oxime of the blocking agent is easily released and remains in the film. When MEK oxime remains in the undercoat layer for a certain amount or more, the surface energy of the undercoat layer is lowered, the coating uniformity of the photosensitive layer laminated on the undercoat layer is deteriorated, and it appears that the image unevenness is manifested. It is done.

  However, by setting the amount of the electron-accepting compound and the remaining MEK oxime in the undercoat layer within the above ranges, both the potential stability can be extended and the coating uniformity of the charge generation layer can be achieved. It is considered that the image density unevenness due to the thickness unevenness of the photosensitive layer is suppressed while the image density decrease is suppressed.

  FIG. 1 schematically shows an example of the layer structure of an electrophotographic photosensitive member (hereinafter sometimes referred to as “photosensitive member”) according to this embodiment. The electrophotographic photosensitive member 1 shown in FIG. 1 has a structure in which an undercoat layer 4, a charge generation layer 5, and a charge transport layer 6 are laminated in this order on a conductive support 2, and the charge generation layer 5 And a charge-separated photosensitive layer 3 in which a charge transport layer 6 is provided separately.

In addition, in this specification, insulation means the range of 10 ¹² Ωcm or more in volume resistivity. On the other hand, the conductivity means a range of 10 ¹⁰ Ωcm or less in volume resistivity.
Hereinafter, each element of the photoreceptor 1 will be described.

-Conductive support-
Examples of the conductive support 2 include metals such as aluminum, nickel, chromium, and stainless steel; and thin films such as aluminum, titanium, nickel, chromium, stainless steel, gold, vanadium, tin oxide, indium oxide, and ITO. Examples thereof include plastic films and the like; paper coated with or impregnated with a conductivity-imparting agent, plastic films and the like.

The shape of the conductive support 2 is not limited to a drum shape, and may be a sheet shape or a plate shape.
When a metal pipe is used as the conductive support 2, the surface may remain as it is, or a process such as mirror cutting, etching, anodizing, rough cutting, centerless grinding, sand blasting, wet honing, etc. is performed in advance. It may be.

-Undercoat layer-
The undercoat layer 4 includes metal oxide particles, an electron-accepting compound having an anthraquinone structure, and a binder resin crosslinked with a blocked isocyanate compound blocked with methyl ethyl ketone oxime (MEK oxime). The content of the electron-accepting compound having an anthraquinone structure with respect to 100 parts by mass of the particles is 0.7 parts by mass or more, and the content of the methyl ethyl ketone oxime in the undercoat layer is 0.2% by mass or less. ing.

(Metal oxide particles)
Examples of the metal oxide particles include zinc oxide, titanium oxide, tin oxide, zirconium oxide and the like, and two or more kinds may be mixed and used.

Examples of the volume average particle diameter of the metal oxide particles include 50 nm to 200 nm.
The volume average particle diameter of the metal oxide particles is measured using, for example, a laser diffraction particle size distribution measuring apparatus (LA-700: manufactured by Horiba, Ltd.). As a measuring method, the sample in the state of dispersion is adjusted so as to have a solid content of 2 g, and ion exchange water is added thereto to make 40 ml. This is put into a cell until an appropriate concentration is reached, and measurement is performed after waiting for 2 minutes. The obtained volume average particle diameter for each channel is accumulated from the smaller one, and the place where the accumulation reaches 50% is defined as the volume average particle diameter.

  As for content of the metal oxide particle contained in the undercoat layer 4, the range of 2.5 mass% or more is mentioned with respect to the whole undercoat layer, for example, The range of 10 mass% or more and 70 mass% or less is mentioned. It is desirable.

The metal oxide particles may be subjected to a surface treatment with a surface treatment agent.
Examples of the surface treatment agent used for the surface treatment of the metal oxide particles include a silane coupling agent, a titanate coupling agent, an aluminum coupling agent, and a surfactant. In particular, a silane coupling agent is an example of a surface treatment agent whose fog is suppressed by adjusting the resistance.

  The silane coupling agent is an organic silane compound (an organic compound containing a silicon atom), and specifically includes, for example, vinyltrimethoxysilane, 3-methacryloxypropyl-tris (2-methoxyethoxy) silane, 2 -(3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2- ( Aminoethyl) -3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, N, N-bis (2-hydroxyethyl) -3-aminopropyltriethoxysilane, 3 -Chloropropyltrimethoxysilane, bi Le triethoxysilane, vinyltris (2-methoxyethoxy silane), 3-methacryloxypropyl trimethoxysilane, etc. N- phenyl-3-aminopropyltrimethoxysilane.

Although the method of surface treatment is not specifically limited, For example, a dry method or a wet method is mentioned.
When the surface treatment is performed by a dry method, for example, the surface treatment agent is directly dropped or dissolved in an organic solvent while stirring the metal oxide particles with a mixer having a large shearing force. Drop and spray with dry air or nitrogen gas. The dropping or spraying is performed at a temperature not higher than the boiling point of the solvent, for example. After the dropping or spraying, baking may be performed by further heating to 100 ° C. or higher.

As the wet method, for example, the metal oxide particles are stirred in a solvent and dispersed using ultrasonic waves, a sand mill, an attritor, a ball mill, etc., and after adding or stirring or dispersing the surface treating agent solution, the solvent is added. Remove. Examples of the solvent removal method include filtration or distillation. After removing the solvent, baking may be performed at 100 ° C. or higher.
In the wet method, the water containing the metal oxide particles may be removed before adding the surface treatment agent, for example, a method of removing with stirring and heating in the solvent used for the surface treatment agent solution, Or the method of azeotropically removing with the said solvent is mentioned.

  As for the quantity of the said surface treating agent adhering to the surface of 100 mass parts of metal oxide particles, the quantity of 0.5 mass part or more and 1.25 mass parts or less is mentioned, for example, 1.25 mass parts or more and 2.00 mass parts is mentioned. Or 0.5 parts by mass or less.

(Electron-accepting compound)
As described above, the electron-accepting compound contained in the undercoat layer 4 is an electron-accepting compound having an anthraquinone structure. Here, the “compound having an anthraquinone structure” is specifically at least one selected from anthraquinone and anthraquinone derivatives, and more specifically a compound represented by the following general formula (1). It is good.

In General Formula (1), R ¹ and R ² each independently represent a hydroxyl group, a methyl group, a methoxymethyl group, a phenyl group, or an amino group, and m and n each independently represents an integer of 0 or more and 4 or less. Represent.
In general formula (1), a compound in which both m and n are 0 is anthraquinone, and in general formula (1), a compound in which at least one of m and n is an integer of 1 to 4 is an anthraquinone derivative. It is. That is, an anthraquinone derivative means a compound in which at least one hydrogen atom of anthraquinone is substituted with a substituent such as a hydroxyl group, a methyl group, a methoxymethyl group, a phenyl group, or an amino group.

Examples of the electron-accepting compound having an anthraquinone structure include, among others, anthraquinone in which m and n are both 0 in the general formula (1), or R ¹ is a hydroxyl group, and m is 1 or more. Preferred examples include hydroxyanthraquinone having 3 or less and n being 0.
Specific examples of the electron-accepting compound include anthraquinone, purpurin, alizarin, quinizarin, ethylanthraquinone, aminohydroxyanthraquinone, and the like.
It is desirable to use a material having a hydroxyanthraquinone structure as the electron-accepting compound.

  Confirmation that the undercoat layer 4 contains an electron-accepting compound having an anthraquinone structure is performed by an analysis method such as gas chromatography, liquid chromatography, FT-IR, Raman spectroscopy, or XPS.

  The content of the electron-accepting compound contained in the undercoat layer 4 is 0.7 parts by mass or more and 0.7 parts by mass or more and 3.0 parts by mass or less with respect to 100 parts by mass of the metal oxide particles. It is preferable that it is 0.7 parts by mass or more and 1.0 part by mass or less.

  The content ratio of the metal oxide particles and the electron accepting compound contained in the undercoat layer 4 of the electrophotographic photoreceptor is confirmed by an analysis method such as NMR spectrum, XPS, atomic absorption analysis, or electron beam microanalyzer.

(Binder resin)
The binder resin contained in the undercoat layer 4 includes acetal resins such as polyvinyl butyral, polyvinyl alcohol resin, casein, polyamide resin, cellulose resin, gelatin, polyurethane resin, polyester resin, methacrylic resin, acrylic resin, and polyvinyl chloride resin. , Polyvinyl acetate resin, vinyl chloride-vinyl acetate-maleic anhydride resin, silicone resin, silicone-alkyd resin, phenolic resin, phenol-formaldehyde resin, melamine resin, urethane resin and other high molecular compounds, charge having charge transporting group A conductive resin such as a transport resin or polyaniline is used.
As content of the binder resin contained in the undercoat layer 4, the range of 5 mass% or more and 60 mass% or less is mentioned with respect to the whole undercoat layer, for example.

(Curing agent)
As a curing agent (crosslinking agent) for crosslinking the binder resin in the undercoat layer 4, a block type isocyanate compound (MEK oxime block type isocyanate compound) using methyl ethyl ketone oxime (MEK oxime) as a blocking agent is used.
As a commercial item of the MEK oxime block type isocyanate compound used in this embodiment, for example, Sumidur BL-3173, Death Module BL3175 (manufactured by Sumitomo Bayern Urethane Co., Ltd.) and the like can be mentioned.

  The addition amount of the MEK oxime block type isocyanate compound in the undercoat layer 4 is such that the binder resin is crosslinked to form a cured film, while the content of the detached MEK oxime in the undercoat layer is 0.2% by mass or less. From the viewpoint of control, 0.02 to 0.18 parts by mass is desirable with respect to 100 parts by mass of the binder resin, and 0.05 to 0.1 parts by mass is more desirable.

  The amount of MEK oxime contained in the undercoat layer 4 is determined by measuring the weight loss rate from 130 ° C. to 230 ° C. using a thermal analyzer, capturing the gas generated at that time, and using a gas chromatograph. By analyzing the components, the amount of MEK oxime is quantified.

Examples of the curing catalyst include publicly known materials, and it is preferable to use an amine catalyst or a metal compound catalyst. Examples of the metal compound catalyst include stannous oxide, dioctyltin dilaurate, dibutyltin dilaurate, dibutyltin diacetate, zinc naphthenate, antimony trichloride, potassium oleate, sodium O-phenylphenate, sodium lead nitrate, Examples thereof include diiron, tetra-n-butyltin, tetra (2-ethylhexyl) titanate, cobalt 2-ethylhexoate, and ferric 2-ethylhexoate iron.
As for the addition amount of a curing catalyst, 0.0001 mass part or more and 0.1 mass part or less are mentioned with respect to 100 mass parts of hardening | curing agents (MEK oxime block type isocyanate compound).

When the undercoat layer 4 is formed, a coating solution (coating solution for forming the undercoat layer) in which the above components are added to a solvent is used.
Examples of the solvent include organic solvents, and specific examples include aromatic hydrocarbon solvents such as toluene and chlorobenzene; aliphatic alcohols such as methanol, ethanol, n-propanol, iso-propanol, and n-butanol. Solvents; ketone solvents such as acetone, cyclohexanone, 2-butanone; halogenated aliphatic hydrocarbon solvents such as methylene chloride, chloroform, ethylene chloride; cyclic or linear ethers such as tetrahydrofuran, dioxane, ethylene glycol, diethyl ether System solvents; ester solvents such as methyl acetate, ethyl acetate, n-butyl acetate; and the like. The solvent may be used alone or in combination of two or more, and is not particularly limited, but a solvent that dissolves the binder resin is preferably used.

  The amount of the solvent used in the coating solution for forming the undercoat layer is not particularly limited as long as the binder resin and the like can be dissolved therein. For example, 0.05 part by mass or more and 200 parts by mass with respect to 1 part by mass of the binder resin. The mass part or less is mentioned.

Examples of the method for dispersing the metal oxide particles in the coating liquid for forming the undercoat layer include, for example, a media disperser such as a ball mill, a vibration ball mill, an attritor, and a sand mill, an agitator, an ultrasonic disperser, a roll mill, and a high-pressure homogenizer. Medialess dispersers such as the above. In addition, as a high-pressure homogenizer, a method such as a collision method in which a dispersion liquid is dispersed by liquid-liquid collision or liquid-wall collision in a high pressure state, or a penetration method in which a fine flow path is dispersed in a high pressure state is used. Also good.
Examples of the method for applying the coating solution for forming the undercoat layer onto the support 2 include, for example, 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. Etc.

  The undercoat layer 4 is formed by applying a coating solution for forming an undercoat layer onto the conductive support 2 and drying by heating. During the drying by heating, MEK oxime is released from the block isocyanate compound, The isocyanate compound and the binder resin are crosslinked and cured. In this embodiment, the undercoat layer 4 is formed so that the content of the MEK oxime detached in the undercoat layer 4 is 0.2% by mass or less.

  As a method for controlling the content (residual amount) of MEK oxime in the undercoat layer 4 to 0.2% by mass or less, specifically, in addition to the adjustment of the addition amount of the MEK oxime block type isocyanate compound, the subbing The residual amount of MEK oxime is adjusted according to the drying conditions when forming the layer 4. Specifically, the residual amount of MEK oxime in the undercoat layer 4 tends to be lowered by increasing the drying temperature, extending the drying time, or increasing the amount of drying air.

  The thickness of the undercoat layer 4 is preferably 15 μm or more, and more preferably 20 μm or more and 50 μm or less.

Resin particles may be added to the undercoat layer 4 to adjust the surface roughness. Examples of the resin particles include silicone resin particles and cross-linked PMMA resin particles.
Further, the surface of the undercoat layer 4 may be polished for adjusting the surface roughness. Examples of the polishing method include buffing, sandblasting, wet honing, and grinding.

-Charge generation layer-
The charge generation layer 5 is formed by dispersing a charge generation material in a binder resin.
As the charge generation material, phthalocyanine pigments such as metal-free phthalocyanine, chlorogallium phthalocyanine, hydroxygallium phthalocyanine, dichlorotin phthalocyanine, and titanyl phthalocyanine are used. In particular, a chlorogallium phthalocyanine crystal having strong diffraction peaks at Bragg angles (2θ ± 0.2 °) of at least 7.4 °, 16.6 °, 25.5 ° and 28.3 ° with respect to CuKα characteristic X-ray, CuKα Strong diffraction peaks at a Bragg angle (2θ ± 0.2 °) of at least 7.7 °, 9.3 °, 16.9 °, 17.5 °, 22.4 ° and 28.8 ° with respect to characteristic X-rays A metal-free phthalocyanine crystal having a Bragg angle (2θ ± 0.2 °) with respect to CuKα characteristic X-ray of at least 7.5 °, 9.9 °, 12.5 °, 16.3 °, 18.6 °, 25. Hydroxygallium phthalocyanine crystals having strong diffraction peaks at 1 ° and 28.3 °, Bragg angles (2θ ± 0.2 °) with respect to CuKα characteristic X-rays of at least 9.6 °, 24.1 ° and 27.2 ° Strong diffraction pea Titanyl phthalocyanine crystal or the like having a are used. In addition, quinone pigments, perylene pigments, indigo pigments, bisbenzimidazole pigments, anthrone pigments, quinacridone pigments and the like are used as charge generation materials. These charge generation materials are used alone or in admixture of two or more.

Examples of the binder resin in the charge generation layer 5 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, and acrylonitrile-styrene. Polymer resin, acrylonitrile-butadiene copolymer resin, polyvinyl acetate resin, polyvinyl formal resin, polysulfone resin, styrene-butadiene copolymer resin, vinylidene chloride-acrylonitrile copolymer resin, vinyl chloride-vinyl acetate-maleic anhydride Resins, silicone resins, phenol-formaldehyde resins, polyacrylamide resins, polyamide resins, poly-N-vinylcarbazole resins, and the like are used. These binder resins are used alone or in combination of two or more.
The mixing ratio (mass ratio) of the charge generation material and the binder resin is, for example, in the range of 10: 1 to 1:10, depending on the material used.

When the charge generation layer 5 is formed, a coating solution in which the above components are added to a solvent is used.
In order to disperse the charge generation material in the binder resin, the coating liquid is subjected to a dispersion treatment. As the dispersing means, a media disperser such as a ball mill, a vibrating ball mill, an attritor or a sand mill, or a medialess disperser such as an agitator, an ultrasonic disperser, a roll mill or a high pressure homogenizer is used. Furthermore, examples of the high-pressure homogenizer include a liquid-liquid collision in a high-pressure state, a collision system that disperses the liquid-liquid by colliding with a liquid-wall, and a penetration system that disperses the fine liquid through a high-pressure state.

As a method of applying the coating liquid for forming the charge generation layer thus obtained on the undercoat layer 4, dip coating, push-up coating, wire bar coating, spray coating, blade coating, knife coating Method, curtain coating method and the like.
The thickness of the charge generation layer 5 is desirably set in a range from 0.01 μm to 5 μm.
Further, for the purpose of adjusting the Fermi energy of the charge generation layer 5, a post-treatment such as an O ₃ exposure treatment may be performed.

-Charge transport layer-
The charge transport layer 6 is formed, for example, by dispersing a charge transport material in a binder resin.
Examples of such charge transport materials include oxadiazole derivatives such as 2,5-bis (p-diethylaminophenyl) -1,3,4-oxadiazole, 1,3,5-triphenyl-pyrazoline, 1- [Pyridyl- (2)]-3- (p-diethylaminostyryl) -5- (p-diethylaminostyryl) pyrazoline and other pyrazoline derivatives, triphenylamine, N, N′-bis (3,4-dimethylphenyl) biphenyl Aromatic tertiary amino compounds such as -4-amine, tri (p-methylphenyl) aminyl-4-amine, dibenzylaniline, N, N′-diphenyl-N, N′-bis (3-methylphenyl) -[1,1-biphenyl] -4,4'-diamine, aromatic third such as N, N'-bis (3-methylphenyl) -N, N'-diphenylbenzidine Diamino compounds, 1,2,4-triazine derivatives such as 3- (4'-dimethylaminophenyl) -5,6-di- (4'-methoxyphenyl) -1,2,4-triazine, 4-diethylaminobenzaldehyde Hydrazone derivatives such as -1,1-diphenylhydrazone, quinazoline derivatives such as 2-phenyl-4-styryl-quinazoline, benzofuran derivatives such as 6-hydroxy-2,3-di (p-methoxyphenyl) benzofuran, p- ( 2,2-diphenylvinyl) -N, N-diphenylaniline and other α-stilbene derivatives, enamine derivatives, carbazole derivatives such as N-ethylcarbazole, hole transport materials such as poly-N-vinylcarbazole and its derivatives, chloranil , Quinone compounds such as broanthraquinone, tetraanoquinodimethane Derived from organic compounds, electron transport materials such as fluorenone compounds such as 2,4,7-trinitrofluorenone, 2,4,5,7-tetranitro-9-fluorenone, xanthone compounds and thiophene compounds, and the above compounds Examples thereof include a polymer having a group in the main chain or side chain. These charge transport materials are used alone or in combination of two or more.

  Examples of the binder resin include polycarbonate resins such as biphenyl copolymerized polycarbonate resin, 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 resin, polyvinyl acetate resin, polyvinyl formal resin, polysulfone resin, styrene-butadiene copolymer resin, vinylidene chloride-acrylonitrile copolymer resin, vinyl chloride-vinyl acetate-anhydrous Maleic resin, silicone resin, phenol-formaldehyde resin, polyacrylamide resin, polyamide resin, insulating resin such as chlorine rubber, and polyvinylcarbazole, Polyvinyl anthracene, organic photoconductive polymers such as polyvinyl pyrene, and the like, used alone or in admixture of two or more.

When the charge transport layer 6 is a surface layer of the electrophotographic photoreceptor 1 (a layer disposed on the side farthest from the conductive support 2 of the photosensitive layer 3), the charge transport layer 6 has lubricating particles (for example, Silica particles, alumina particles, fluorine-based resin particles such as polytetrafluoroethylene (PTFE), and silicone-based resin particles) may be included. These lubricating particles may be used as a mixture of two or more.
Further, when the charge transport layer 6 is a surface layer of the electrophotographic photoreceptor 1, a fluorine-modified silicone oil may be added to the charge transport layer 6. Examples of the fluorine-modified silicone oil include compounds having a fluoroalkyl group.
In addition, as mass ratio of the charge transport material and binder resin in the charge transport layer 6, the range of 10: 1 to 1: 5 is mentioned, for example. That is, the content of the charge transport material with respect to the entire charge transport layer 6 is, for example, in the range of 17% by mass to 91% by mass.

The charge transport layer 6 is formed using a coating liquid for forming a charge transport layer in which the above components are added to a solvent.
Examples of the solvent include known organic solvents, for example, aromatic hydrocarbon solvents such as toluene and chlorobenzene, aliphatic alcohol solvents such as methanol, ethanol, n-propanol, iso-propanol, and n-butanol, acetone, and cyclohexanone. , Ketone solvents such as 2-butanone, halogenated aliphatic hydrocarbon solvents such as methylene chloride, chloroform and ethylene chloride, cyclic or linear ether solvents such as tetrahydrofuran, dioxane, ethylene glycol and diethyl ether, methyl acetate, Examples thereof include ester solvents such as ethyl acetate and n-butyl acetate. Moreover, you may use these solvents individually or in mixture of 2 or more types. Any solvent can be used as long as it can dissolve the binder resin as a mixed solvent.

  Examples of a dispersion method for dispersing the lubricating particles in the coating liquid for forming the charge transport layer include, for example, a media disperser such as a ball mill, a vibration ball mill, an attritor, and a sand mill, a stirring, an ultrasonic disperser, Examples thereof include a method using a medialess disperser such as a roll mill, a high-pressure homogenizer, and a nanomizer. Further, 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 the fine liquid is penetrated and dispersed in a high pressure state.

As a method for forming the charge transport layer 6, for example, the charge transport layer forming coating solution is applied onto the charge generation layer 5 of the conductive support 2 on which the undercoat layer 4 and the charge generation layer 5 are formed. And a method of forming the charge generation layer 6 by drying.
Examples of the method for applying the coating liquid for forming the charge transport layer on the charge generation layer 5 include dip coating, push-up coating, wire bar coating, spray coating, blade coating, knife coating, and curtain. Examples thereof include a coating method.
And after apply | coating the said coating liquid on the electric charge generation layer 5, the solvent in a coating liquid is removed by a heat drying process. Examples of the film thickness of the charge transport layer 6 include a range of 5 μm to 50 μm.

For the purpose of preventing deterioration of the photoreceptor due to ozone, nitrogen oxide, or light or heat generated in the image forming apparatus, an antioxidant, a light stabilizer, a heat stabilizer, etc. are included in each layer constituting the photosensitive layer 3. Additives may be added. For example, examples of the antioxidant include hindered phenol, hindered amine, paraphenylenediamine, arylalkane, hydroquinone, spirochroman, spiroidanone and their derivatives, organic sulfur compounds, and organic phosphorus compounds. Examples of light stabilizers include derivatives such as benzophenone, benzoazole, dithiocarbamate, and tetramethylpipen.
The photoreceptor 1 of the present embodiment has the charge transport layer 6 as the outermost surface layer, but may have a configuration in which a protective layer is further formed on the charge transport layer.

<Image forming apparatus>
Next, an image forming apparatus provided with the electrophotographic photosensitive member according to this embodiment will be described.
An image forming apparatus according to this embodiment includes the electrophotographic photosensitive member, a charging device that charges the electrophotographic photosensitive member, and an electrostatic latent image that forms an electrostatic latent image on the surface of the charged electrophotographic photosensitive member. An image forming apparatus, a developing apparatus for developing a toner image by developing the electrostatic latent image formed on the surface of the electrophotographic photosensitive member with toner, and the toner image formed on the surface of the electrophotographic photosensitive member. And a transfer device for transferring to a recording medium.

-First embodiment-
FIG. 2 schematically shows the basic configuration of the image forming apparatus according to the first embodiment. An image forming apparatus 200 shown in FIG. 2 includes, for example, the electrophotographic photosensitive member 1 of the above embodiment, a charging device 208 (charging means) that is connected to the power source 209 and charges the electrophotographic photosensitive member 1, and a charging device 208. An exposure device 210 (electrostatic latent image forming means) for exposing the charged electrophotographic photosensitive member 1 to form an electrostatic latent image, and developing the electrostatic latent image formed by the exposure device 210 with toner A developing device 211 (developing means) that forms a toner image by developing with an agent, a transfer device 212 (transfer means) that transfers the toner image formed on the surface of the electrophotographic photosensitive member 1 to the recording medium 500, and a post-transfer A toner removing device 213 (toner removing means) that removes toner remaining on the surface of the electrophotographic photosensitive member 1, and a fixing device 215 (fixing) that fixes the toner image transferred to the recording medium 500 to the recording medium 500. Includes a stage), the.
In addition, the image forming apparatus 200 shown in FIG. 2 may include a charge removing unit that removes charges remaining on the surface of the electrophotographic photosensitive member after the toner image on the surface of the electrophotographic photosensitive member is transferred.

  The charging device 208 has a charging member, and a voltage is applied to the charging member when the photosensitive member 1 is charged. In the case of the contact charging method as shown in FIG. 2, the applied voltage is positive or negative from 50 V to 2000 V (preferably from 250 V to 1000 V, more preferably, depending on the required charging potential of the electrophotographic photosensitive member 1. Is a type in which a DC voltage of 350 V or more and 750 V or less is applied.

Examples of the charging member include a roller, a brush, and a film. Among them, as the roller-shaped charging member (hereinafter sometimes referred to as “charging roller”), for example, a member composed of a material whose electric resistance is adjusted to a range of 10 ³ Ω to 10 ⁸ Ω can be mentioned. . The charging roller may be a single layer or may be composed of a plurality of layers.
When a charging roller is used as the charging member, examples of the pressure that contacts the photoreceptor 1 include a range of 250 mgf to 600 mgf.

Examples of the material constituting the charging member include urethane rubber, silicone rubber, fluorine rubber, chloroprene rubber, butadiene rubber, EPDM (ethylene-propylene-diene copolymer rubber), epichlorohydrin rubber and other synthetic rubber, polyolefin, polystyrene, chloride Examples thereof include an elastomer composed of vinyl or the like as a main material and a suitable amount of a conductivity imparting agent such as conductive carbon, metal oxide, or ionic conductive agent.
In addition, nylon, polyester, polystyrene, polyurethane, silicone, and other resins are made into paints, and conductive additives such as conductive carbon, metal oxides, and ionic conductive agents are blended in appropriate amounts, and the resulting paints are applied by dip coating and spraying. You may laminate | stack and use by methods, such as application | coating and roll coating.

When a charging roll is used as the charging member, the charging roll is brought into contact with the surface of the photoreceptor 1 so that the charging means is driven and rotated even if the charging means does not have a driving means. A means may be attached and rotated at a peripheral speed different from that of the photoreceptor 1.
A non-contact charging type charging device that charges the photosensitive member 1 without contacting it may be employed.

As the exposure apparatus 210, known exposure means is used. Specifically, for example, an optical system device that performs exposure with a light source such as a semiconductor laser, an LED (Light Emitting Diode), or a liquid crystal shutter is used. Examples of the light amount at the time of writing include a range of 0.5 mJ / m ² or more and 5.0 mJ / m ² or less on the surface of the photoreceptor.

As the developing device 211, for example, a developing brush (developer holding body) to which a developer containing a carrier and toner adheres is brought into contact with an electrostatic latent image holding body and developed, and conductive rubber, conductive rubber Examples thereof include a contact type or non-contact type one-component development type developing unit that attaches toner on an elastic material transporting roll (developer holding body) and develops the toner on the electrostatic latent image holding body.
The toner is not particularly limited as long as it is a known toner. Specifically, for example, the toner may include at least a binder resin and, if necessary, a colorant, a release agent, and the like.

  The method for producing the toner is not particularly limited. For example, a known pulverization method, a wet melt spheronization method prepared in a dispersion medium, suspension polymerization, dispersion polymerization, emulsion polymerization aggregation method and the like are known. Examples thereof include a toner production method using a polymerization method.

  When the developer is a two-component developer containing a toner and a carrier, the carrier is not particularly limited. For example, a core material such as a magnetic metal such as iron oxide, nickel or cobalt, or a magnetic oxide such as ferrite or magnetite. And a carrier coated with a resin layer on the surface of the core material (non-coated carrier). In the two-component developer, for example, the mixing ratio (mass ratio) of the toner and the carrier is in the range of toner: carrier = 1: 100 to 30: 100, and even in the range of 3: 100 to 20: 100. Good.

  Examples of the transfer device 212 include a roller-type contact-type charging member, a contact-type transfer charger using a belt, a film, a rubber blade, or the like, or a scorotron transfer charger using a corona discharge or a corotron transfer charger. Can be mentioned.

The toner removing device 213 is for removing residual toner adhering to the surface of the electrophotographic photosensitive member 1 after the transfer process, and the electrophotographic photosensitive member 1 thus cleaned is repeatedly subjected to the above image forming process. Provided. As the toner removing device 213, a foreign matter removing member (cleaning blade), brush cleaning, roll cleaning, and the like are used. Among these, it is desirable to use a cleaning blade. Examples of the material for the cleaning blade include urethane rubber, neoprene rubber, and silicone rubber.
Note that the toner removing device 213 need not be provided when residual toner is not a problem, for example, when the toner hardly remains on the surface of the photoreceptor 1.

A basic image forming process of the image forming apparatus 200 will be described.
First, the charging device 208 charges the surface of the photoreceptor 1 to a predetermined potential. Next, the surface of the charged photoreceptor 1 is exposed by the exposure device 210 based on the image signal to form an electrostatic latent image.

Next, the developer is held on the developer holding member of the developing device 211, the held developer is conveyed to the photosensitive member 1, and the developer holding member and the photosensitive member 1 are in proximity (or contact). It is supplied to the electrostatic latent image. As a result, the electrostatic latent image is visualized and becomes a toner image.
The developed toner image is conveyed to the position of the transfer device 212 and transferred directly to the recording medium 500 by the transfer device 212.

  Next, the recording medium 500 to which the toner image is transferred is conveyed to the fixing device 215, and the toner image is fixed to the recording medium 500 by the fixing device 215. Examples of the fixing temperature include 100 ° C. or higher and 180 ° C. or lower.

On the other hand, the toner particles remaining on the photoreceptor 1 without being transferred to the recording medium 500 are transported to the contact position with the toner removing device 213 and collected by the toner removing device 213.
As described above, image formation by the image forming apparatus 200 is performed.

-Second Embodiment-
FIG. 3 schematically shows the basic configuration of the image forming apparatus according to the second embodiment. An image forming apparatus 220 shown in FIG. 3 is an intermediate transfer type image forming apparatus. In the housing 400, four electrophotographic photosensitive members 1a, 1b, 1c, and 1d are arranged in parallel along the intermediate transfer belt 409. ing. For example, an image is formed in which the photoreceptor 1a is yellow, the photoreceptor 1b is magenta, the photoreceptor 1c is cyan, and the photoreceptor 1d is black.

Here, the electrophotographic photoreceptors 1a, 1b, 1c, and 1d mounted on the image forming apparatus 220 are the electrophotographic photoreceptors of this embodiment, respectively.
Each of the electrophotographic photoreceptors 1a, 1b, 1c, and 1d rotates in one direction (counterclockwise on the paper surface), and charging rolls 402a, 402b, 402c, and 402d, and developing devices 404a, 404b, and 404c along the rotation direction. 404d, primary transfer rolls 410a, 410b, 410c, 410d and cleaning blades 415a, 415b, 415c, 415d. The developing devices 404a, 404b, 404c, and 404d supply toners of four colors, black, yellow, magenta, and cyan, stored in toner cartridges 405a, 405b, 405c, and 405d, respectively, and primary transfer rolls 410a, 410b, 410c and 410d are in contact with the electrophotographic photoreceptors 1a, 1b, 1c and 1d through the intermediate transfer belt 409, respectively.

  Further, a laser light source (exposure device) 403 is disposed in the housing 400, and irradiates the surfaces of the electrophotographic photoreceptors 1a, 1b, 1c, and 1d after charging with laser light emitted from the laser light source 403. As a result, in the rotation process of the electrophotographic photoreceptors 1a, 1b, 1c, and 1d, charging, exposure, development, primary transfer, and cleaning (removal of foreign matters such as toner) are sequentially performed, and the toner images of the respective colors are intermediate. The image is transferred onto the transfer belt 409 in an overlapping manner. Then, the following image forming process is performed on the electrophotographic photoreceptors 1a, 1b, 1c, and 1d after the toner images are transferred onto the intermediate transfer belt 409, respectively.

  The intermediate transfer belt 409 is supported with tension by a drive roll 406, a back roll 408, and a support roll 407, and rotates without causing deflection due to the rotation of these rolls. Further, the secondary transfer roll 413 is disposed so as to be in contact with the back roll 408 through the intermediate transfer belt 409. The intermediate transfer belt 409 that has passed through the position sandwiched between the back roll 408 and the secondary transfer roll 413 is cleaned by, for example, a cleaning blade 416 disposed facing the drive roll 406, and then forms the next image. Used repeatedly in the process.

  In addition, a container 411 for storing a recording medium is provided in the housing 400, and the recording medium 500 such as paper in the container 411 is sandwiched between the intermediate transfer belt 409 and the secondary transfer roll 413 by the transfer roll 412. After being sequentially transferred to a position, and further to a position sandwiched between two fixing rolls 414 that are in contact with each other, the sheet is discharged to the outside of the housing 400.

In the above description, the case where the intermediate transfer belt 409 is used as the intermediate transfer member has been described. However, the intermediate transfer member may have a belt shape like the intermediate transfer belt 409 or a drum shape. May be.
In the case of a belt shape, a known resin is used as the resin material constituting the base material of the intermediate transfer member. For example, polyimide resin, polycarbonate resin (PC), polyvinylidene fluoride (PVDF), polyalkylene terephthalate (PAT), ethylenetetrafluoroethylene copolymer (ETFE) / PC, ETFE / PAT, PC / PAT blend material, polyester Resin materials such as polyether ether ketone and polyamide, and resin materials using these as main raw materials. Further, a resin material and an elastic material may be blended and used.

  The recording medium according to the above embodiment is not particularly limited as long as it is a medium that transfers a toner image formed on an electrophotographic photosensitive member.

<Process cartridge>
FIG. 4 schematically shows a basic configuration of an example of a process cartridge including the electrophotographic photosensitive member of the present embodiment. The process cartridge 300 develops the electrostatic latent image formed on the electrophotographic photosensitive member 1 by exposure with a developer including toner, together with the electrophotographic photosensitive member 1, a charging device 208 for charging the electrophotographic photosensitive member 1. A developing device 211 that forms a toner image, a toner removing device 213 that removes toner remaining on the surface of the electrophotographic photosensitive member 1 after transfer, and an opening 218 for exposure are combined using an attachment rail 216. It is an integrated one.

The process cartridge 300 includes a transfer device 212 that transfers the toner image formed on the surface of the electrophotographic photosensitive member 1 to the recording medium 500, and a fixing that fixes the toner image transferred to the recording medium 500 to the recording medium 500. The apparatus 215 is detachable from the main body of the image forming apparatus including other components (not shown), and constitutes the image forming apparatus together with the main body of the image forming apparatus.
In addition to the electrophotographic photosensitive member 1, the charging device 208, the developing device 211, the toner removing device 213, and the opening 218 for exposure, the process cartridge 300 exposes the surface of the electrophotographic photosensitive member 1 (see FIG. (Not shown).
It should be noted that the process cartridge of the present embodiment only needs to include at least the electrophotographic photoreceptor 1.

  Hereinafter, the present embodiment will be specifically described with reference to examples, but the present embodiment is not limited to these examples.

[Production of electrophotographic photosensitive member]
<Example 1>
-Formation of undercoat layer-
60 parts by mass of zinc oxide particles (manufactured by Teika Co., Ltd., average particle size: 70 nm, specific surface area value: 15 m ² / g) are stirred and mixed with 500 parts by mass of tetrahydrofuran and used as a silane coupling agent (surface treatment agent) as KBM603 (N 1.25 parts by mass of 2- (aminoethyl) -3-aminopropyltrimethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd.) was added to 100 parts by mass of the zinc oxide particles, and the mixture was stirred for 2 hours. Thereafter, methanol was removed by distillation under reduced pressure, baking was performed at 120 ° C. for 3 hours, and zinc oxide particles surface-treated with a silane coupling agent were obtained.

  100 parts by mass of zinc oxide particles surface-treated with the silane coupling agent, 1 part by mass of anthraquinone as an electron accepting compound, and blocked isocyanate (Sumijoule BL-3173, manufactured by Sumitomo Bayern Urethane Co., Ltd.) 22.5 as a curing agent 38 parts by mass of a solution obtained by dissolving part by mass and 25 parts by mass of butyral resin (ESREC BM-1, manufactured by Sekisui Chemical Co., Ltd.) in 142 parts by mass of methyl ethyl ketone, and 25 parts by mass of methyl ethyl ketone are mixed, and glass beads having a diameter of 1 mm. Was dispersed for 5 hours with a sand mill to obtain a dispersion.

  To the obtained dispersion, 0.008 parts by mass of dioctyltin dilaurate and 6.5 parts by mass of silicone resin particles (Tospearl 145, manufactured by GE Toshiba Silicone) are added as a catalyst, and a coating solution for forming an undercoat layer. Got. This coating solution is applied onto an aluminum substrate having a diameter of 30 mm by a dip coating method, followed by drying and curing under conditions of 190 ° C., 24 minutes, and a wind speed of 1.1 m / s to obtain an undercoat layer having a thickness of 15 μm. It was.

-Formation of charge generation layer-
Next, as a charge generation material, it has strong diffraction peaks at Bragg angles (2θ ± 0.2 °) with respect to CuKα characteristic X-rays of at least 7.4 °, 16.6 °, 25.5 ° and 28.3 °. Using a glass bead having a diameter of 1 mm, a mixture of 15 parts by mass of chlorogallium phthalocyanine crystal, 10 parts by mass of vinyl chloride-vinyl acetate copolymer resin (VMCH, manufactured by Nippon Union Carbide) and 300 parts by mass of n-butyl alcohol was used. Then, it was dispersed in a sand mill for 4 hours to obtain a coating solution for forming a charge generation layer. This coating solution for forming the charge generation layer was dip-coated on the undercoat layer and dried at 150 ° C. for 5 minutes to obtain a charge generation layer having a thickness of 0.2 μm.

-Formation of charge transport layer-
Next, 8 parts by mass of tetrafluoroethylene resin particles (average particle size: 0.2 μm), 0.015 parts by mass of fluorinated alkyl group-containing methacrylic copolymer (weight average molecular weight: 30000), 4 parts by mass of tetrahydrofuran, 1 part by mass of toluene was kept at a liquid temperature of 20 ° C. and stirred for 48 hours to obtain a tetrafluoroethylene resin particle suspension A.

  Next, 4 parts by mass of N, N′-diphenyl-N, N′-bis (3-methylphenyl)-[1,1 ′] biphenyl-4,4′-diamine as a charge transport material, and bisphenol Z type 6 parts by mass of a polycarbonate resin (viscosity average molecular weight: 40,000) and 0.1 part by mass of 2,6-di-tert-butyl-4-methylphenol as an antioxidant are mixed to obtain 24 parts by mass of tetrahydrofuran. And 11 mass parts of toluene was mixed and dissolved, and the mixed solution B was obtained.

After adding the tetrafluoroethylene resin particle suspension A to the mixed solution B and stirring and mixing it, using a high-pressure homogenizer (manufactured by Yoshida Kikai Kogyo Co., Ltd.) equipped with a through-type chamber having a fine flow path. , The dispersion treatment under pressure up to 500 kgf / cm ² was repeated 6 times, and fluorine-modified silicone oil (trade name: FL-100, manufactured by Shin-Etsu Silicone) was added to 5 ppm, and stirred to form a charge transport layer. A coating solution was obtained. This coating solution was applied on the charge generation layer to a thickness of 24.0 μm and dried at 150 ° C. for 25 minutes to form a charge transport layer, thereby obtaining the intended electrophotographic photosensitive member. In this way, the photoreceptor of Example 1 was obtained.

<Example 2>
The formation of the undercoat layer was carried out in the same manner as in Example 1 except that the electron-accepting compound was 0.7 parts by mass, and drying and curing were performed at 180 ° C. for 24 minutes and at a wind speed of 1.0 m / s. The photoreceptor of Example 2 was obtained.

<Example 3>
In the formation of the undercoat layer, the same procedure as in Example 1 except that the electron-accepting compound is alizarin and the addition amount is 0.7 parts by mass, 190 ° C., 24 minutes, and the wind speed is 1.5 m / s. Thus, a photoreceptor of Example 3 was obtained.

<Example 4>
In the formation of the undercoat layer, Example 4 was carried out in the same manner as in Example 4, except that the electron-accepting compound was 3 parts by mass and dried and cured under the conditions of 190 ° C., 28 minutes, and wind speed of 1.5 m / s. A photoreceptor was obtained.

<Comparative Example 1>
Comparative Example 1 was carried out in the same manner as in Example 1 except that the electron-accepting compound was 5 parts by mass in the formation of the undercoat layer and was dried and cured under the conditions of 180 ° C., 24 minutes, and wind speed of 1.0 m / s. An electrophotographic photoreceptor was prepared.

<Comparative example 2>
In the formation of the subbing layer, Comparative Example 2 was carried out in the same manner as in Example 1, except that the electron-accepting compound was 1 part by mass, and it was dried and cured under the conditions of 180 ° C., 24 minutes, and wind speed 0.7 m / s. An electrophotographic photoreceptor was prepared.

<Comparative Example 3>
In the formation of the undercoat layer, a comparison was made in the same manner as in Example 1, except that the electron-accepting compound was 0.5 parts by mass, and drying and curing was performed at 190 ° C. for 24 minutes and at a wind speed of 1.1 m / s. The electrophotographic photoreceptor of Example 3 was produced.

<Comparative example 4>
An electrophotographic photoreceptor of Comparative Example 4 was produced in the same manner as in Example 1 except that the electron accepting compound was changed to quinacridone in the formation of the undercoat layer.

<Comparative Example 5>
In the formation of the undercoat layer, the blocked isocyanate compound “Sumidur BL-3173” was changed to “Sumidur BL-3272” in which the blocking agent was ε-caprolactam in the same manner as in Example 1, An electrophotographic photosensitive member of Comparative Example 5 was produced.

<Comparative Example 6>
In the formation of the undercoat layer, an electrophotographic photoreceptor of Comparative Example 6 was produced in the same manner as in Example 1 except that the amount of MEK oxime in the blocked isocyanate compound was reduced by 50%.

(Evaluation)
[Measurement of blocking agent content of undercoat layer]
About the undercoat single layer film used when producing the photoconductors of the above examples and comparative examples, the weight loss rate of 130 ° C. to 230 ° C. was measured using an EXSTAR TG / DTA6300 thermal analyzer manufactured by SII Nano Technology. The gas generated at that time was captured, and the components of the gas were analyzed using an HP-6890 gas chromatograph manufactured by Hewlett-Packard Co. to determine the amount of MEK oxime.

[Evaluation of uneven image density]
Image density unevenness was evaluated by incorporating the photoconductor produced in Example or Comparative Example into a modified DocuCentre 505a manufactured by Fuji Xerox Co., Ltd., and outputting a single 30% halftone image on A4 size paper. Using X-Rite 404 manufactured by Rite, the density of the four corners of the paper (4 cm from the edge of the paper) was measured, and the difference between the maximum value and the minimum value of the output density was used as a quantitative index for image density unevenness.

[Life Evaluation]
By incorporating the photoconductor produced in the above example or comparative example into a modified machine of DocuCentre 505a, a 30% halftone image is continuously output on the entire surface under conditions of high temperature and high humidity (ie, room temperature 28 ° C., humidity 85%), The number of sheets until the decrease in density occurred was used as a quantitative index for life evaluation.

  Table 1 shows the electron accepting compound and the block-type isocyanate compound contained in the undercoat layer obtained above, the drying conditions of the undercoat layer, and the evaluation results.

  The image density unevenness evaluation is 0.1 or more and has a problem in actual use, and the life evaluation is 10,000 or less and has a problem in actual use.

  It can be seen that the use of the electrophotographic photosensitive member of the example suppresses image density unevenness and suppresses a decrease in density when images are repeatedly formed.

1, 1a, 1b, 1c, 1d Electrophotographic photoreceptor, 2 conductive support, 3 photosensitive layer, 4 undercoat layer, 5 charge generation layer, 6 charge transport layer, 200 image forming apparatus, 208 charging apparatus, 210 exposure Device, 211 developing device, 212 transfer device, 213 toner removing device, 215 fixing device, 220 image forming device, 404a, 404b, 404c, 404d developing device, 500 recording medium

Claims (4)

A conductive support;
A subbing layer disposed on the conductive support, the binder resin crosslinked with a metal oxide particle, an electron-accepting compound having an anthraquinone structure, and a blocked isocyanate compound blocked with methyl ethyl ketone oxime The content of the electron-accepting compound having the anthraquinone structure with respect to 100 parts by mass of the metal oxide particles is 0.7 parts by mass or more, and the content of the methyl ethyl ketone oxime in the undercoat layer is 0 An undercoat layer of 2% by mass or less;
A photosensitive layer disposed on the undercoat layer;
An electrophotographic photosensitive member having:   The electrophotographic photoreceptor according to claim 1, wherein the electron-accepting compound having an anthraquinone structure is an electron-accepting compound having a hydroxyanthraquinone structure. The electrophotographic photosensitive member according to claim 1 or 2,
A charging device for charging the electrophotographic photosensitive member;
An electrostatic latent image forming apparatus for forming an electrostatic latent image on the surface of the charged electrophotographic photosensitive member;
A developing device for developing the electrostatic latent image formed on the surface of the electrophotographic photosensitive member with toner to form a toner image;
A transfer device for transferring the toner image formed on the surface of the electrophotographic photosensitive member to a recording medium;
An image forming apparatus. At least the electrophotographic photoreceptor according to claim 1 or 2,
A process cartridge that is detachable from the image forming apparatus.