JP2011064906A - Electrophotographic photoreceptor and method for manufacturing the same, and process cartridge and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor in which coarseness and denseness of fluorine-containing resin particles are suppressed compared to an electrophotographic photoreceptor where a photosensitive layer simply contains fluorine-containing resin particles and a fluorine-based grafted polymer. <P>SOLUTION: The electrophotographic photoreceptor 1 includes a conductive support 2 and a photosensitive layer 3 disposed on the conductive support. The photosensitive layer contains fluorine-containing resin particles, a specified fluorinated alkyl group-containing methacrylic copolymer and a charge transporting material. When light of a wavelength of 300 nm or more and 1,000 nm or less is condensed and the surface of the photoreceptor is vertically scanned and irradiated with the condensed light in a region where a latent image is to be formed in the photosensitive layer, a value ΔI satisfies ΔI≥0.9, wherein ΔI is obtained by dividing the minimum value of intensity of scattered light when the light irradiating the photosensitive layer is scattered on the surface of the photosensitive layer by the maximum value of intensity of the scattered light. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

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

  Electrophotographic image formation has the advantages of high speed and high print quality, and is therefore widely used in fields such as copying machines and laser beam printers. As an electrophotographic photoreceptor (hereinafter sometimes simply referred to as “photoreceptor”) used in an image forming apparatus, organic light is cheaper in terms of manufacturing and disposal than a photoreceptor using an inorganic photoconductive material. An electrophotographic photosensitive member using a conductive material has become the mainstream. Among them, a functionally separated organic photoreceptor in which a charge generation layer that generates charges upon exposure and a charge transport layer that transports charges as a photosensitive layer is excellent in terms of electrophotographic characteristics, and various proposals have been made. Made and put to practical use.

  Organic photoreceptors are generally inferior in mechanical strength to inorganic photoreceptors, and are subject to abrasion and abrasion due to mechanical external forces such as members for removing residual toner on the surface, developing brushes, and paper. Short life. Further, in a system using a contact charging method that has been used in recent years from the viewpoint of environmental protection, the wear of the photoconductor may be significantly increased as compared with a non-contact charging method using corotron. Thus, if the durability of the photoreceptor is insufficient, it may cause a decrease in image density due to a reduction in sensitivity, a generation of fog on an image due to a decrease in charging potential, and the like.

  For example, a method has been proposed in which the surface energy of the surface layer of the photoreceptor is reduced and the surface frictional force is reduced by dispersing fluorine-containing resin particles in the charge transport layer. Further, since the fluorine-containing resin particles have low dispersibility and high cohesiveness, a method for improving the dispersibility of the fluorine-containing resin particles by adding a fluorine-based graft polymer as a dispersion aid has been proposed ( For example, see Patent Document 1).

JP-A-63-221355

  An object of the present invention is to provide an electrophotographic photosensitive member in which the density of the fluorine-containing resin particles is suppressed as compared with an electrophotographic photosensitive member in which the photosensitive layer simply includes fluorine-containing resin particles and a fluorine-based graft polymer.

（一般式（Ｉ）及び（ＩＩ）において、ｌ、ｍ、ｎは１以上の正数をそれぞれ独立して表し、ｐ、ｑ、ｒ、ｓは０または１以上の正数をそれぞれ独立して表し、ｔは８未満の正数を表し、Ｒ^１、Ｒ^２、Ｒ^３、Ｒ^４は水素原子またはアルキル基をそれぞれ独立して表し、Ｘはアルキレン鎖、ハロゲン置換アルキレン鎖、―Ｓ―、―Ｏ―、―ＮＨ―、または単結合を表し、Ｙはアルキレン鎖、ハロゲン置換アルキレン鎖、―（Ｃ_ｚＨ_２ｚ−１（ＯＨ））―、または単結合を表し、―（Ｃ_ｚＨ_２ｚ−１（ＯＨ））―におけるｚは１以上の正数を表す。）
請求項２の発明は、フッ素含有樹脂粒子と、下記一般式（Ｉ）及び（ＩＩ）で表わされる構造を有するメタクリル共重合体と、電荷輸送性材料とを含む液を用意する工程と、前記液を塗布槽の底部から供給するとともに上縁から溢れさせながら、導電性支持体を含む被塗布物を浸漬塗布する際、前記液の温度Ｔ〔℃〕及び前記液の循環流量Ｆ〔Ｌ／分〕がＴ×Ｆ≧５０を満足する条件下で、前記液により浸漬塗布することにより前記被塗布物の表面に塗膜を形成する工程と、前記被塗布物の表面に形成された塗膜を乾燥させて感光層を形成する工程と、を含む、電子写真感光体の製造方法である。

（一般式（Ｉ）及び（ＩＩ）において、ｌ、ｍ、ｎは１以上の正数をそれぞれ独立して表し、ｐ、ｑ、ｒ、ｓは０または１以上の正数をそれぞれ独立して表し、ｔは８未満の正数を表し、Ｒ^１、Ｒ^２、Ｒ^３、Ｒ^４は水素原子またはアルキル基をそれぞれ独立して表し、Ｘはアルキレン鎖、ハロゲン置換アルキレン鎖、―Ｓ―、―Ｏ―、―ＮＨ―、または単結合を表し、Ｙはアルキレン鎖、ハロゲン置換アルキレン鎖、―（Ｃ_ｚＨ_２ｚ−１（ＯＨ））―、または単結合を表し、―（Ｃ_ｚＨ_２ｚ−１（ＯＨ））―におけるｚは１以上の正数を表す。）
請求項３の発明は、請求項１に記載の電子写真感光体を備えたプロセスカートリッジである。
請求項４の発明は、請求項１に記載の電子写真感光体と、前記電子写真感光体を帯電させる帯電装置と、帯電した前記電子写真感光体を露光して静電潜像を形成する静電潜像形成装置と、前記電子写真感光体に形成された前記静電潜像をトナーを含む現像剤により現像してトナー像を形成する現像装置と、前記電子写真感光体に形成された前記トナー像を被転写媒体に転写する転写装置と、を備える画像形成装置である。 In order to achieve the above object, the following present invention is provided.
The invention of claim 1 includes a conductive support and a photosensitive layer disposed on the conductive support, wherein the photosensitive layer includes fluorine-containing resin particles, the following general formulas (I) and ( II) a methacrylic copolymer having a structure represented by II) and a charge transport material, condensing light having a wavelength of 300 nm to 1000 nm, and perpendicular to the surface of the photosensitive layer and the photosensitive layer When the area where the latent image is formed is irradiated while scanning, the minimum value of the scattered light intensity when the irradiated light is scattered on the surface of the photosensitive layer is divided by the maximum value of the scattered light intensity. The electrophotographic photosensitive member has a value ΔI satisfying ΔI ≧ 0.9.

(In the general formulas (I) and (II), l, m, and n each independently represent a positive number of 1 or more, and p, q, r, and s each independently represent 0 or a positive number of 1 or more. T represents a positive number less than 8, R ¹ , R ² , R ³ , R ⁴ each independently represents a hydrogen atom or an alkyl group, X represents an alkylene chain, a halogen-substituted alkylene chain, —S—, —O—, —NH—, or a single bond, Y represents an alkylene chain, a halogen-substituted alkylene chain, — (C _z H _2z-1 (OH)) —, or a single bond, and — (C _z H _2z Z in _-1 (OH))-represents a positive number of 1 or more.)
The invention of claim 2 is a step of preparing a liquid containing fluorine-containing resin particles, a methacrylic copolymer having a structure represented by the following general formulas (I) and (II), and a charge transporting material; While supplying the liquid from the bottom of the coating tank and overflowing from the upper edge, when the object including the conductive support is dip coated, the liquid temperature T [° C.] and the liquid circulation flow rate F [L / Min] satisfying T × F ≧ 50, a step of forming a coating film on the surface of the coating object by dip coating with the liquid, and a coating film formed on the surface of the coating object And a step of forming a photosensitive layer by drying the electrophotographic photosensitive member.

(In the general formulas (I) and (II), l, m, and n each independently represent a positive number of 1 or more, and p, q, r, and s each independently represent 0 or a positive number of 1 or more. T represents a positive number less than 8, R ¹ , R ² , R ³ , R ⁴ each independently represents a hydrogen atom or an alkyl group, X represents an alkylene chain, a halogen-substituted alkylene chain, —S—, —O—, —NH—, or a single bond, Y represents an alkylene chain, a halogen-substituted alkylene chain, — (C _z H _2z-1 (OH)) —, or a single bond, and — (C _z H _2z Z in _-1 (OH))-represents a positive number of 1 or more.)
According to a third aspect of the present invention, there is provided a process cartridge comprising the electrophotographic photosensitive member according to the first aspect.
According to a fourth aspect of the present invention, there is provided an electrophotographic photosensitive member according to the first aspect, a charging device for charging the electrophotographic photosensitive member, and an electrostatic latent image formed by exposing the charged electrophotographic photosensitive member to exposure. An electrostatic latent image forming device; a developing device for developing the electrostatic latent image formed on the electrophotographic photosensitive member with a developer containing toner to form a toner image; and the electrophotographic photosensitive member formed on the electrophotographic photosensitive member. And a transfer device that transfers a toner image to a transfer medium.

According to the first aspect of the present invention, there is provided an electrophotographic photosensitive member in which the density of the fluorine-containing resin particles is suppressed as compared with an electrophotographic photosensitive member in which the photosensitive layer simply includes fluorine-containing resin particles and a fluorine-based graft polymer. The
According to the invention of claim 2, the electrophotographic photosensitive member in which the density of the fluorine-containing resin particles is suppressed as compared with a method for producing an electrophotographic photosensitive member in which the photosensitive layer simply includes fluorine-containing resin particles and a fluorine-based graft polymer. A method of manufacturing a body is provided.
According to the invention of claim 3, there is provided a process cartridge in which the density unevenness of the image is less likely to occur as compared with a process cartridge in which the photosensitive layer includes an electrophotographic photosensitive member simply including fluorine-containing resin particles and a fluorine-based graft polymer. The
According to the invention of claim 4, there is provided an image forming apparatus in which image density unevenness is less likely to occur compared to an image forming apparatus in which the photosensitive layer includes an electrophotographic photosensitive member that simply includes fluorine-containing resin particles and a fluorine-based graft polymer. Provided.

1 is a schematic view showing a part of a cross section of an electrophotographic photoreceptor according to an exemplary embodiment. It is the schematic which shows an example of the apparatus which forms the electric charge transport layer which comprises the electrophotographic photoreceptor which concerns on this embodiment by dip coating. It is the schematic which shows the method of measuring the scattered light intensity in the surface of an electrophotographic photoreceptor in the circumferential direction. It is the schematic which shows the method of measuring the scattered light intensity in the surface of an electrophotographic photoreceptor in an axial direction. 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 will be described with reference to the accompanying drawings as appropriate. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and redundant description is omitted.

  According to the study by the present inventors, in order to improve mechanical durability, the charge transport layer as the outermost surface becomes fluorine-containing resin particles and a dispersion aid in addition to the charge transport material and the binder resin. In the case of an electrophotographic photosensitive member containing a fluorine-based graft polymer, the fluorine-containing resin particles are likely to have a dense region and a rough region, and the amount of wear of the charge transport layer after continuous printing varies depending on the density. End up. As a result, unevenness in the thickness of the charge transport layer occurs, so that unevenness in image density is likely to occur.

Therefore, as a result of examining the state of the surface layer in which thickness unevenness is unlikely to occur with respect to such an electrophotographic photosensitive member, the present inventors, for example, emit light having a wavelength of 300 nm or more and 1000 nm or less on the surface of the electrophotographic photosensitive member to 10 mm ^2. When the irradiation light is scattered on the photoconductor, the light is condensed so as to be an area, and is irradiated perpendicularly to the surface of the electrophotographic photoconductor and scanning the surface of the photoconductor. The value ΔI obtained by dividing the minimum value of the scattered light intensity by the maximum value of the scattered light intensity satisfies ΔI ≧ 0.9, so that the density of the fluorine-containing resin particles can be effectively suppressed. It has been found that the thickness unevenness of the surface layer of the photoreceptor is suppressed and the image density unevenness is stably suppressed.

  Furthermore, as a result of intensive studies on a method of forming a surface layer containing fluorine-containing resin particles and a fluorine-based graft polymer, the present inventors have applied dip coating while controlling the liquid temperature and the circulation flow rate to a specific range. Thus, it has been found that the density of the fluorine-containing resin particles is suppressed, and as a result, the thickness unevenness of the surface layer of the electrophotographic photosensitive member after continuous printing is suppressed, and the density unevenness of the image is stably suppressed.

FIG. 1 schematically shows a part of a cross section of an example of the electrophotographic photosensitive member of this embodiment. The electrophotographic photoreceptor 1 includes a function-separated type photosensitive layer 3 in which a charge generation layer 5 and a charge transport layer 6 are separately provided. An undercoat layer 4 and a charge generation layer are formed on a conductive support 2. The layer 5 and the charge transport layer 6 are stacked in this order. Here, the charge transport layer 6 is a surface layer (a layer disposed on the side farthest from the support 2) in the photoreceptor 1, and will be described in detail later. In addition to the charge transport material and the binder resin, for example, an average It contains fluorine-containing resin particles having a sphericity of 0.7 or less and a specific fluorinated alkyl group-containing methacrylic copolymer.
Hereinafter, each element of the photoreceptor 1 will be described.

-Conductive support-
Any conductive support 2 may be used as long as it is conventionally used. In the present specification, “conductive” means a range of 10 ¹⁰ Ωcm or less in volume resistivity.
For example, the conductive support 2 is provided with a metal such as aluminum, nickel, chromium, and stainless steel, and a thin film such as aluminum, titanium, nickel, chromium, stainless steel, gold, vanadium, tin oxide, indium oxide, and ITO. Examples thereof include a plastic film and the like, or a paper coated with or impregnated with a conductivity imparting agent, and a plastic film. The shape of the support 2 is not limited to a drum shape, and may be a sheet shape or a plate shape.
For example, when a metal pipe is used as the conductive support 2, the surface may be left as it is, or a process such as mirror cutting, etching, anodizing, rough cutting, centerless grinding, sand blasting, liquid honing, etc. may be performed in advance. It may be done.

-Undercoat layer-
The undercoat layer 4 is provided as necessary for the purpose of preventing light reflection on the surface of the support 2 and preventing inflow of unnecessary carriers from the support 2 to the photosensitive layer 3. Materials for forming the undercoat layer 3 include metal powders such as aluminum, copper, nickel, and silver, conductive metal oxides such as antimony oxide, indium oxide, tin oxide, and zinc oxide, carbon fiber, and carbon black. And a conductive material such as graphite powder dispersed in a binder resin and coated on the support 2. Further, two or more kinds of metal oxide particles may be mixed and used. Furthermore, the powder resistance may be controlled by performing surface treatment with a coupling agent on the metal oxide particles.

  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 resins, vinyl chloride-vinyl acetate-maleic anhydride resins, silicone resins, silicone-alkyd resins, phenolic resins, phenol-formaldehyde resins, melamine resins, urethane resins, and other known polymer resin compounds, and charge transport properties A charge transporting resin having a group or a conductive resin such as polyaniline may be used. Among these, resins that are insoluble in the upper coating solvent are preferably used, and phenol resins, phenol-formaldehyde resins, melamine resins, urethane resins, epoxy resins, and the like are particularly preferable.

The ratio between the metal oxide particles and the like in the undercoat layer 4 and the binder resin is not particularly limited, and can be arbitrarily set within a range where desired electrophotographic photoreceptor characteristics can be obtained.
When the undercoat layer 4 is formed, a coating solution in which the above components are added to a specific solvent is used. Examples of such solvents include aromatic hydrocarbon solvents such as toluene and chlorobenzene, aliphatic alcohol solvents such as methanol, ethanol, n-propanol, iso-propanol, and n-butanol, acetone, cyclohexanone, and 2-butanone. Ketone solvents, halogenated aliphatic hydrocarbon solvents such as methylene chloride, chloroform, ethylene chloride, cyclic or linear ether solvents such as tetrahydrofuran, dioxane, ethylene glycol, diethyl ether, methyl acetate, ethyl acetate, n acetate -Organic solvents, such as ester solvents, such as butyl. These solvents are used alone or in combination of two or more. When mixing, the solvent used may be a mixed solvent that dissolves the binder resin.

  In addition, as a method for dispersing metal oxide particles and the like in the coating solution for forming the undercoat layer, a media disperser such as a ball mill, a vibration ball mill, an attritor, a sand mill, a horizontal sand mill, an agitator, an ultrasonic disperser, a roll mill Medialess dispersers such as high-pressure homogenizers are used. 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 of applying the coating solution for forming the undercoat layer thus obtained on the support 2, 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, Examples include a curtain coating method.
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 in order to adjust the surface roughness. As the resin particles, silicone resin particles, cross-linked PMMA resin particles, and the like are used.
Further, the surface of the undercoat layer 4 may be polished for adjusting the surface roughness. As a polishing method, buffing, sandblasting, liquid honing, grinding, or the like is used.

-Intermediate layer-
Although illustration is omitted, an intermediate layer may be further provided on the undercoat layer 4 in order to improve electrical characteristics, improve image quality, improve image quality maintainability, and improve photosensitive layer adhesion. As the binder resin used for the intermediate layer, acetal resins such as polyvinyl butyral, polyvinyl alcohol resin, casein, polyamide resin, cellulose resin, gelatin, polyurethane resin, polyester resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinyl In addition to polymer resins such as acetate resin, vinyl chloride-vinyl acetate-maleic anhydride resin, silicone resin, silicone-alkyd resin, phenol-formaldehyde resin, melamine resin, zirconium, titanium, aluminum, manganese, silicon atom, etc. And organometallic compounds containing These compounds are used alone or as a mixture or polycondensate of a plurality of compounds. Among them, an organometallic compound containing zirconium or silicon is advantageous in terms of performance such as low residual potential, little potential change due to environment, and little potential change due to repeated use.

As the solvent used for forming the intermediate layer, known organic solvents, for example, aromatic hydrocarbon solvents such as toluene and chlorobenzene, aliphatics such as methanol, ethanol, n-propanol, iso-propanol, and n-butanol Alcohol solvents, ketone solvents such as acetone, cyclohexanone and 2-butanone, halogenated aliphatic hydrocarbon solvents such as methylene chloride, chloroform and ethylene chloride, cyclic or linear such as tetrahydrofuran, dioxane, ethylene glycol and diethyl ether Examples include ether solvents, ester solvents such as methyl acetate, ethyl acetate, and n-butyl acetate. These solvents are used alone or in combination of two or more. When mixing, the solvent used may be a mixed solvent that dissolves the binder resin.
As the coating method for forming the intermediate layer, usual methods such as a dip coating method, a push-up coating method, a wire bar coating method, a spray coating method, a blade coating method, a knife coating method, and a curtain coating method are used.

  In addition to improving the coatability of the upper layer, the intermediate layer also serves as an electrical blocking layer. However, if the thickness is too large, the electrical barrier becomes too strong, causing desensitization and potential increase due to repetition. There is a fear. Therefore, when the intermediate layer is formed, the thickness is set to be, for example, 0.1 μm or more and 3 μm or less. Further, the intermediate layer in this case may be used as the undercoat layer 4.

-Charge generation layer-
The charge generation layer 5 is formed by dispersing a charge generation material in an appropriate binder resin. As such a charge generation material, phthalocyanine pigments such as metal-free phthalocyanine, chlorogallium phthalocyanine, hydroxygallium phthalocyanine, dichlorotin phthalocyanine, and titanyl phthalocyanine are used. A chlorogallium phthalocyanine crystal having strong diffraction peaks at least at 7.4 °, 16.6 °, 25.5 ° and 28.3 °, a Bragg angle (2θ ± 0.2 °) to CuKα characteristic X-ray of at least 7 Metal-free phthalocyanine crystals having strong diffraction peaks at .7 °, 9.3 °, 16.9 °, 17.5 °, 22.4 °, and 28.8 °, Bragg angle (2θ ± 0) with respect to CuKα characteristic X-rays .2 °) at least 7.5 °, 9.9 °, 12.5 °, 16.3 °, 18.6 ° Hydroxygallium phthalocyanine crystals having strong diffraction peaks at 25.1 ° 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 A titanyl phthalocyanine crystal having a strong diffraction peak at 0 ° is 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 may be used alone or in combination 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, polyvinyl acetate resin, polyvinyl formal resin, polysulfone resin, styrene-butadiene copolymer resin, vinylidene chloride-acrylonitrile copolymer resin, vinyl chloride-vinyl acetate-maleic anhydride resin Silicone resin, phenol-formaldehyde resin, polyacrylamide resin, polyamide resin, poly-N-vinylcarbazole resin and the like are used. These binder resins are used alone or in combination of two or more. The mixing ratio of the charge generation material and the binder resin is preferably in the range of 10: 1 to 1:10.

  When the charge generation layer 5 is formed, a coating solution in which the above components are added to a predetermined solvent is used. Examples of such solvents include aromatic hydrocarbon solvents such as toluene and chlorobenzene, aliphatic alcohol solvents such as methanol, ethanol, n-propanol, iso-propanol, and n-butanol, acetone, cyclohexanone, and 2-butanone. Ketone solvents, halogenated aliphatic hydrocarbon solvents such as methylene chloride, chloroform, ethylene chloride, cyclic or linear ether solvents such as tetrahydrofuran, dioxane, ethylene glycol, diethyl ether, methyl acetate, ethyl acetate, n acetate -Organic solvents, such as ester solvents, such as butyl. These solvents are used alone or in combination of two or more. When mixing, the solvent used may be a mixed solvent that dissolves the binder resin.

In order to disperse the charge generation material in the resin, the coating liquid is subjected to a dispersion treatment. As a dispersion method, a media disperser such as a ball mill, a vibrating ball mill, an attritor, a sand mill, or a horizontal sand mill, or a medialess disperser such as an agitator, an ultrasonic disperser, a roll mill, or a high-pressure homogenizer is used. 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.
Examples of methods for applying the coating solution thus obtained onto the undercoat layer 4 include dip coating, push-up coating, wire bar coating, spray coating, blade coating, knife coating, curtain coating, and the like. Is mentioned.
The thickness of the charge generation layer 5 is preferably set in the range of 0.01 μm to 5 μm, more preferably 0.05 μm to 2.0 μm.

-Charge transport layer-
The charge transport layer 6 comprises at least a charge transport material, fluorine-containing resin particles, and a methacrylic copolymer containing a fluorinated alkyl group having a structure represented by the following general formulas (I) and (II) (as appropriate An alkyl group-containing methacrylic copolymer ”). The fluorinated alkyl group-containing methacrylic copolymer is obtained by graft polymerization from, for example, a macromonomer composed of an acrylic ester compound, a methacrylic ester compound, and the like, perfluoroalkylethyl methacrylate, and perfluoroalkyl methacrylate.

In the general formulas (I) and (II), l, m, and n each independently represent a positive number of 1 or more, and p, q, r, and s each independently represent 0 or a positive number of 1 or more. , T represents a positive number less than 8, R ¹ , R ² , R ³ , R ⁴ each independently represents a hydrogen atom or an alkyl group, X represents an alkylene chain, a halogen-substituted alkylene chain, —S—, — O—, —NH—, or a single bond, Y represents an alkylene chain, a halogen-substituted alkylene chain, — (C _z H _2z-1 (OH)) —, or a single bond, and — (C _z H _2z— Z in ₁ (OH)) — represents a positive number of 1 or more.

  When the carbon main chain length of the fluorinated alkyl group of the fluorinated alkyl group-containing methacrylic copolymer is 2 or more, the adsorptivity of the fluorinated alkyl group-containing methacrylic copolymer to the fluorine-containing resin particles Is suppressed, and the function as a dispersion aid is improved. For this reason, non-uniform dispersion of the fluorine-containing resin particles present in the surface layer is suppressed, and the effect of sufficiently improving the durability of the photoreceptor is easily obtained. Furthermore, aggregation of the fluorine-containing resin particles is suppressed, and poor image quality due to aggregation is unlikely to occur.

  On the other hand, when the carbon main chain length of the fluorinated alkyl group of the fluorinated alkyl group-containing methacrylic copolymer is less than 7, the binder contained in the fluorinated alkyl group-containing methacrylic copolymer and the photosensitive layer Good compatibility with resin. For this reason, the interface between the fluorinated alkyl group-containing methacrylic copolymer and the binder resin is suppressed from becoming a trap site, and the residual potential is unlikely to rise during repeated use under high temperature and high humidity.

  Further, the molecular weight of the fluorinated alkyl group-containing methacrylic copolymer is preferably 20,000 or more and 100,000 or less, more preferably 30,000 or more and 50,000 or less. When the molecular weight of the fluorinated alkyl group-containing methacrylic copolymer is 20000 or more, the dispersion stability is suppressed from becoming insufficient. On the other hand, if the molecular weight is 100000 or less, a decrease in compatibility with the binder resin is suppressed, the interface is prevented from becoming a trap site, and the residual potential increases during repeated use under high temperature and high humidity. It is suppressed.

  The content of the fluorinated alkyl group-containing methacrylic copolymer in the charge transport layer 6 is desirably 1% by mass or more and 5% by mass or less with respect to the content of the fluorine-containing resin particles. When the addition amount of the fluorinated alkyl group-containing methacrylic copolymer with respect to the content of the fluorine-containing resin particles is 1% by mass or more, the dispersion of the fluorine-containing resin particles is suppressed from being insufficient. In addition, if the content is 5% by mass or less, the surface of the fluorine-containing resin particles with respect to the fluorinated alkyl group-containing methacrylic copolymer that functions as a dispersion aid by adsorbing to the surface of the fluorine-containing resin particles. Excess fluorinated alkyl group-containing methacrylic copolymer that has not been adsorbed onto the charge transport layer is suppressed from being present in the charge transport layer 6, and the expression of trap sites that accumulate charges is suppressed. As a result, the residual potential is prevented from increasing due to repeated use under high temperature and high humidity, and the photoconductor is less prone to decrease in density.

  Further, the content of the fluorine-containing resin particles with respect to the total solid content of the charge transport layer 6 is desirably 2% by mass or more and 15% by mass or less. When the content of the fluorine-containing resin particles with respect to the total solid content of the charge transport layer 6 is 2% by mass or more, the modification of the charge transport layer 6 due to the dispersion of the fluorine-containing resin particles is suppressed. Moreover, when the said content is 15 mass% or less, the fall of light transmittance and the fall of film | membrane intensity | strength become difficult to occur.

  Examples of the fluorine-containing resin particles used in the present embodiment include a tetrafluoroethylene resin, a trifluorinated ethylene resin, a hexafluoropropylene resin, a vinyl fluoride resin, a vinylidene fluoride resin, a difluorodiethylene chloride resin, and the like. It is desirable to appropriately select one or more of these copolymers, and tetrafluoroethylene resin and vinylidene fluoride resin are particularly desirable.

  The primary particle size of the fluorine-containing resin particles is desirably 0.05 μm or more and 1 μm or less, and more desirably 0.1 μm or more and 0.5 μm or less. If the primary particle size is 0.05 μm or more, aggregation during dispersion is difficult to proceed, whereas if it is 1 μm or less, image quality defects are difficult to occur.

The charge transport layer 6 includes, in addition to the above components, a charge transport material for expressing an original function as a charge transport layer, and further 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'-bis (3-methylphenyl) -N, N'-diphenyl Aromatic tertiary diamino compounds such as benzidine, 3- (4′-dimethylaminophenyl) -5,6-di- (4′-methoxyphenyl) -1, 1,2,4-triazine derivatives such as 1,4-triazine, hydrazone derivatives such as 4-diethylaminobenzaldehyde-1,1-diphenylhydrazone, quinazoline derivatives such as 2-phenyl-4-styryl-quinazoline, 6-hydroxy-2 Benzofuran derivatives such as 1,3-di (p-methoxyphenyl) benzofuran, α-stilbene derivatives such as p- (2,2-diphenylvinyl) -N, N-diphenylaniline, enamine derivatives, carbazole such as N-ethylcarbazole Derivatives, hole transport materials such as poly-N-vinylcarbazole and its derivatives, quinone compounds such as chloranil and broanthraquinone, tetraanoquinodimethane compounds, 2,4,7-trinitrofluorenone, 2,4, Full such as 5,7-tetranitro-9-fluorenone Examples thereof include an electron transport material such as an oleone compound, a xanthone compound, and a thiophene compound, and a polymer having a group composed of the above-described compound in a main chain or a side chain. These charge transport materials are used alone or in combination of two or more.

  Examples of the binder resin in the charge transport layer 6 include polycarbonate resin such as bisphenol A type or bisphenol Z type, acrylic resin, methacrylic resin, polyarylate resin, polyester resin, polyvinyl chloride resin, polystyrene resin, acrylonitrile- Styrene copolymer resin, acrylonitrile-butadiene copolymer resin, polyvinyl acetate resin, polyvinyl formal resin, polysulfone resin, styrene-butadiene copolymer resin, vinylidene chloride-acrylonitrile copolymer resin, vinyl chloride-vinyl acetate-anhydrous Insulating resins such as maleic acid resin, silicone resin, phenol-formaldehyde resin, polyacrylamide resin, polyamide resin, chlorine rubber, and polyvinylcarbazole, polyvinyl Anthracene, organic photoconductive polymers such as polyvinyl pyrene, and the like. These binder resins may be used alone or in combination of two or more.

The charge transport layer 6 is formed using a coating solution obtained by adding each of the above components to a specific solvent. Solvents used for forming the charge transport layer include known organic solvents, for example, aromatic hydrocarbon solvents such as toluene and chlorobenzene, and fats such as methanol, ethanol, n-propanol, iso-propanol, and n-butanol. Aromatic alcohol solvents, ketone solvents such as acetone, cyclohexanone and 2-butanone, halogenated aliphatic hydrocarbon solvents such as methylene chloride, chloroform and ethylene chloride, cyclic or straight chain such as tetrahydrofuran, dioxane, ethylene glycol and diethyl ether And ether solvents such as ester solvents such as methyl acetate, methyl acetate, ethyl acetate, and n-butyl acetate. These solvents may be used alone or in combination. When mixing, the solvent used may be a mixed solvent that dissolves the binder resin. The mixing ratio of the charge transport material and the binder resin is preferably 10: 1 to 1: 5.
For example, when preparing a dispersion liquid of fluorine-containing resin particles and a fluorinated alkyl group-containing methacrylic copolymer in advance, toluene alone may be used as a solvent.

  Examples of the dispersion method of the coating liquid for dispersing the fluorine-containing resin particles in the charge transport layer 6 include a media disperser such as a ball mill, a vibration ball mill, an attritor, a sand mill, a horizontal sand mill, an agitator, an ultrasonic disperser, and a roll mill. Medialess dispersers such as high-pressure homogenizers are used. 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 of coating the charge transport layer forming coating solution thus obtained on the charge generation layer 5, desirably, a method of dip coating while circulating the charge transport layer forming coating solution is used. FIG. 2 shows an outline of an apparatus for performing dip coating. The apparatus includes a coating tank 53 that contains a coating liquid 52 for forming a charge transport layer and dip-coats an object 51 to be coated, and supplies the coating liquid 52 for forming a charge transport layer to the center of the bottom of the coating tank 53. There is a mouth 55, and around the coating tank 53, there is a receiving part 56 for collecting the coating liquid 52 overflowing from the upper edge of the tank 53. Further, although not shown, an elevating device that immerses and removes the coating object 51 with respect to the coating liquid 52 accommodated in the tank 53, a circulation pump that again supplies the collected coating liquid 52 into the tank 53 from the supply port, A temperature control device for controlling the temperature of the coating liquid 52 is provided.

  When dip coating is performed using this apparatus, a coating liquid 52 for forming a charge transport layer is placed in a coating tank 53, and an object to be coated in the coating liquid 52 in the tank 53, that is, a conductive layer having a charge generation layer on the outermost surface. Application is performed by immersing the conductive support 51 and gradually removing the conductive support 51 from the coating liquid 52 in the tank 53 by raising the conductive support 51 or lowering the coating tank 53. A coating film 54 is formed. At this time, the charge transport layer forming coating liquid 52 is supplied from the supply port 55 of the coating tank 53 and is supplied so as to overflow from the upper edge, and the recovered coating liquid 52 overflowing from the coating tank 53 is again supplied from the supply port 55. Circulate by supplying.

Thus, when the coating film 54 is formed on the surface of the conductive support 51 by circulating the coating liquid 52 for forming the charge transport layer, in this embodiment, the temperature T [° C.] of the coating liquid 52 and the coating liquid 52 Dip coating is performed under conditions where the circulation flow rate F [L / min] satisfies T × F ≧ 50. Here, the circulation flow rate means the amount (L) per unit time (minute) of the coating solution supplied to the dip coating tank (immersion tank inner diameter: 50 mm) shown in FIG. In the present embodiment, the inner diameter of the immersion tank is an example, and varies depending on the diameter of the photoreceptor.
By performing dip coating while controlling the temperature and circulation flow rate to satisfy the relationship of T × F ≧ 50, the coating film 54 in which the fluorine-containing resin particles are sufficiently dispersed is formed. It is desirable that 62.5 ≦ T × F ≦ 245 from the viewpoint of suppressing bubbles generated during circulation of the charge transport liquid, suppressing film thickness unevenness, and reducing the amount of solvent volatilization, and precipitating the charge transport material. More preferably, 5 ≦ T × F ≦ 168.

Further, the temperature of the coating liquid 52 for forming the charge transport layer is 25 ° C. or more from the viewpoint of preventing the precipitation of the charge transport material, and is 32 from the viewpoint of preventing the solvent from remarkably evaporating and lowering the viscosity of the coating liquid 52. It is desirable that the temperature is not higher than ° C.
On the other hand, the circulation flow rate of the coating liquid for forming the charge transport layer is 1.7 [L / min] or more from the viewpoint of suppressing film thickness unevenness, and 7 from the viewpoint of suppressing bubbles generated during the circulation of the charge transport liquid. It is desirable that it is 0.0 [L / min] or less.

The coating film 54 formed on the charge generation layer of the conductive support 51 by dip coating is dried at, for example, 100 ° C. or more and 140 ° C. or less for 30 minutes. Thereby, a charge transport layer is formed on the charge generation layer.
The thickness of the charge transport layer is mainly adjusted by the speed at which the conductive support 51 is relatively removed from the coating liquid 52 when performing dip coating, preferably 5 μm to 50 μm, more preferably 10 μm to 40 μm. The following range is set.

For the purpose of preventing deterioration of the photoreceptor due to ozone, nitrogen oxide, light, or heat generated in the electrophotographic apparatus, an antioxidant, a light stabilizer, and heat stability are included in each of the layers 5 and 6 constituting the photosensitive layer 3. An additive such as an agent may be added. For example, examples of the antioxidant include hindered phenol, hindered amine, paraphenylenediamine, arylalkane, hydroquinone, spirochroman, spiroidanone and derivatives thereof, organic sulfur compounds, and organic phosphorus compounds. Examples of light stabilizers include derivatives such as benzophenone, benzoazole, dithiocarbamate, and tetramethylpipen.
Further, for the purpose of improving the smoothness of the surface, a leveling agent such as silicone oil may be added to the surface layer.

  The electrophotographic photoreceptor 1 according to the present embodiment collects light having a wavelength of 300 nm or more and 1000 nm or less, and has a region perpendicular to the surface of the photosensitive layer 3 and a region where a latent image is formed on the photosensitive layer 3. When irradiating while scanning, the value ΔI obtained by dividing the minimum value of the scattered light intensity when the irradiated light is scattered on the surface of the photosensitive layer 3 by the maximum value of the scattered light intensity satisfies ΔI ≧ 0.9. To meet.

The scattered light intensity ratio on the surface of the electrophotographic photoreceptor 1 according to the present embodiment is obtained as follows. 3 and 4 show an example of a method for measuring the scattered light intensity on the surface of the electrophotographic photosensitive member 1 according to the present embodiment.
For example, a xenon lamp or the like is used as the light source 10 and the condensing lens 12 is used to collect light having a wavelength of 300 nm or more and 1000 nm or less on the surface of the photoreceptor 1 so as to have an area of 5 mm ² or more and 100 mm ² or less. As shown in FIG. 3, the light is irradiated perpendicularly to the surface toward the central axis C of the photoreceptor 1. Note that the irradiation light L does not necessarily need to include light in all wavelength ranges from a wavelength of 300 nm to 1000 nm.

  On the other hand, the optical sensor 20 is installed so as to be located at a certain angle θ and a certain distance with respect to the irradiation light L so as to pick up the light scattered on the surface of the photosensitive member 1. Although the position of the sensor 20 depends on the intensity of the irradiation light L, for example, it is within a range of 45 ° with respect to a line connecting the light irradiation position on the surface of the photosensitive member 1 and the central axis C of the photosensitive member 1. And the optical sensor 20 is installed so that a light-receiving part may be located within 10 cm from the light irradiation position on the surface of the photoreceptor 1. Then, the photoconductor 1 is rotated in the circumferential direction while the light source 10 and the optical sensor 20 are fixed. Thereby, the scattered light intensity is measured in the circumferential direction A of the photosensitive member 1 with a width of 1 cm, for example.

On the other hand, in the axial direction, as shown in FIG. 4, the scattered high intensity is measured by moving the photosensitive member 1 in the axial direction B with the light source 10 and the optical sensor 20 fixed. Note that when the scattered light intensity is measured by moving the photosensitive member 1 in the axial direction B, the vicinity of both ends of the photosensitive member 1 is a region that does not contribute to image formation, and thus a region where a latent image is formed (image forming region). ) Measure scattered light intensity only for R.
In this way, the rotation of the photosensitive member 1 in the circumferential direction A and the movement in the axial direction B are combined to scan the entire image forming region R to measure the scattered light intensity, and the maximum and minimum values of the scattered light intensity are measured. Is calculated, and a value (ΔI) obtained by dividing the minimum value of the scattered light intensity by the maximum value of the scattered light intensity is obtained.
Then, in the circulation type dip coating as described above, the coating film is formed under the condition that the temperature T [° C.] and the circulation flow rate F [L / min] of the charge transport layer forming coating solution satisfy T × F ≧ 50. By forming the charge transport layer, the electrophotographic photosensitive member 1 of the present embodiment satisfying ΔI ≧ 0.9 is obtained.

  The electrophotographic photosensitive member 1 of the present embodiment is a function-separated type having the charge generation layer 5 and the charge transport layer 6. However, the electrophotographic photoreceptor 1 has a single photosensitive layer that serves as both the charge generation layer and the charge transport layer. You may adopt a figure.

  Next, an image forming apparatus and a process cartridge provided with the electrophotographic photosensitive member according to this embodiment will be described.

<Image forming apparatus>
-First embodiment-
FIG. 5 schematically shows the basic configuration of the image forming apparatus according to the first embodiment. An image forming apparatus 200 shown in FIG. 5 is charged by the electrophotographic photosensitive member 1 of this embodiment, a contact charging type charging device 208 that is connected to the power source 209 and charges the electrophotographic photosensitive member 1, and the charging device 208. An electrostatic latent image forming device (exposure device) 210 that exposes the electrophotographic photosensitive member 1 to form an electrostatic latent image, and the electrostatic latent image formed by the exposure device 210 is developed with a developer containing toner. A developing device 211 that forms a toner image, a transfer device 212 that transfers the toner image formed on the surface of the electrophotographic photosensitive member 1 to the transfer medium 500, and remains on the surface of the electrophotographic photosensitive member 1 after the transfer. A toner removing device 213 that removes toner and a static eliminator 214 that removes a residual potential of the electrophotographic photosensitive member 1 are provided. For example, the static eliminator 214 is not necessarily provided. However, when the electrophotographic photosensitive member is repeatedly used, a phenomenon that the residual potential of the electrophotographic photosensitive member is brought into the next cycle is prevented. , The image quality is further improved.

  The charging device 208 has a charging roll, and a voltage is applied to the charging roll when charging the photoreceptor 1. As the voltage range, the DC voltage is preferably positive or negative 50 V or more and 2000 V or less, more preferably 100 V or more and 1500 V or less, depending on the required photosensitive member charging potential. When the AC voltage is superimposed, the peak-to-peak voltage is 400 V to 1800 V, preferably 800 V to 1600 V, and more preferably 1200 V to 1600 V. The frequency of the AC voltage is 50 Hz to 20000 Hz, preferably 100 Hz to 5000 Hz.

  As the charging roll, one provided with an elastic layer, a resistance layer, a protective layer, etc. on the outer peripheral surface of the core material is preferably used. Even if the charging roll is brought into contact with the photosensitive member 1 and does not have a driving unit, the charging roll rotates with the rotation of the photosensitive member 1 and functions as a charging unit. May be charged by rotating at different peripheral speeds. The applied voltage may be a DC voltage or a DC voltage with an AC voltage superimposed on it.

  As the exposure device 210, an optical system device that exposes the surface of the electrophotographic photosensitive member in a desired image-like manner using a light source such as a semiconductor laser, an LED (Light Emitting Diode), or a liquid crystal shutter is used.

  As the developing device 211, a known developing device using a normal or reversal developer such as a one-component system or a two-component system is used. The shape of the toner used in the developing device 211 is not particularly limited, and an irregular shape, a spherical shape, or another specific shape may be used.

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

-Second Embodiment-
FIG. 6 schematically shows the basic configuration of the image forming apparatus of the second embodiment. An image forming apparatus 220 shown in FIG. 6 is an intermediate transfer type image forming apparatus, and four electrophotographic photosensitive members 1 a, 1 b, 1 c, and 1 d are arranged in parallel along the intermediate transfer belt 409 in the housing 400. 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, the 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. 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 between the back roll 408 and the secondary transfer roll 413 is cleaned by, for example, a cleaning blade 416 disposed in the vicinity of the drive roll 406 and then repeatedly used for the next image forming process. Is done.

  In addition, a container 411 that accommodates a transfer medium is provided in the housing 400, and the transfer medium 500 such as paper in the container 411 is moved between the intermediate transfer belt 409 and the secondary transfer roll 413 by a transfer roll 412. In addition, after being sequentially transferred between two fixing rolls 414 that are in contact with each other, the paper 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 transfer 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. For example, when transferring directly from the electrophotographic photosensitive member 1 to a transfer medium such as paper as in the first embodiment shown in FIG. 5, the paper or the like is the transfer medium. Further, when an intermediate transfer member is used as in the second embodiment shown in FIG. 6, the intermediate transfer member is a transfer medium.

  As described above, in the image forming apparatuses 200 and 220 including the electrophotographic photosensitive member 1 according to this embodiment, the layer thickness unevenness of the surface layer of the photosensitive member 1 after continuous printing is suppressed, and the image density unevenness is reduced. Stable and suppressed.

<Process cartridge>
FIG. 7 schematically shows a basic configuration of an example of a process cartridge including the electrophotographic photosensitive member of the present embodiment. In addition to the electrophotographic photosensitive member 1, the process cartridge 300 includes a charging device 208, a developing device 211, a toner removing device 213, an opening portion 218 for exposure, and an opening portion 217 for discharge exposure, and a mounting rail 216. Used in combination and integrated.
The process cartridge 300 is detachably attached to an image forming apparatus main body including a transfer device 212, a fixing device 215, and other components (not shown), and the image forming apparatus together with the image forming apparatus main body. Configure.

  As described above, when the process cartridge 300 including the electrophotographic photosensitive member 1 according to the present embodiment is used, the layer thickness unevenness of the surface layer of the photosensitive member 1 after continuous printing is suppressed, and the image density unevenness is stabilized. It is suppressed.

Examples will be described below.
Example 1
100 parts by mass of zinc oxide (average particle size: 70 nm, manufactured by Teika, specific surface area value: 15 m ² / g) is stirred and mixed with 500 parts by mass of tetrahydrofuran, and KBM603 (manufactured by Shin-Etsu Chemical Co., Ltd.) is used as a silane coupling agent. 25 parts by mass was added and stirred for 2 hours. Thereafter, tetrahydrofuran was distilled off under reduced pressure, followed by baking at 120 ° C. for 3 hours. Thereby, the zinc oxide particle surface-treated with the silane coupling agent was obtained.

  60 parts by mass of the surface-treated zinc oxide particles, 0.6 parts by mass of alizarin, 13.5 parts by mass of blocked isocyanate (Sumidule 3173, manufactured by Sumitomo Bayern Urethane Co., Ltd.) as a curing agent, and butyral resin (BM-1, manufactured by Sekisui Chemical Co., Ltd.) 15 parts by mass, 38 parts by mass of a solution obtained by dissolving 85 parts by mass of methyl ethyl ketone and 25 parts by mass of methyl ethyl ketone are mixed, and 4 mm in a sand mill using glass beads having a diameter of 1 mm. Time dispersion was performed to obtain a dispersion.

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

  Next, as a charge generation material, it has strong diffraction peaks at Bragg angles (2θ ± 0.2 °) with respect to CuKα characteristic X-rays of at least 7.4 °, 16.6 °, 25.5 ° and 28.3 °. 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 Co., Ltd.), and 300 parts by mass of n-butyl alcohol was prepared using glass beads having a diameter of 1 mm. The resulting mixture was dispersed in a sand mill for 4 hours to obtain a coating solution for forming a charge generation layer. This coating solution was dip-coated on the undercoat layer and then dried at 120 ° C. for 5 minutes to form a charge generation layer having a thickness of 0.2 μm.

In order to obtain a coating liquid for forming a charge transport layer, first, the following A liquid and B liquid were prepared.
Liquid A: 0.5 parts by mass of tetrafluoroethylene resin particles (average particle size: 0.2 μm) and a methacrylic copolymer having a structure represented by the following formulas (A) and (B) (weight average molecular weight 30) , 000) 0.01 parts by mass together with 5 parts by mass of toluene, and sufficiently mixed to obtain a suspension of tetrafluoroethylene resin particles.

  In the structural formulas (A) and (B), l and m are equal integers of 1 or more, and n is about 60.

  Liquid B: 2 parts by mass of N, N′-bis (3-methylphenyl) -N, N′-diphenylbenzidine as a charge transport substance, N, N′-bis (3,4-dimethylphenyl) biphenyl-4-amine 2 parts by mass, 6 parts by mass of a bisphenol Z-type polycarbonate resin (viscosity average molecular weight: 40,000), 0.1 part by mass of 2,6-di-t-butyl-4-methylphenol as an antioxidant are mixed, and 24 parts by mass of tetrahydrofuran and 11 parts by mass of toluene were mixed and dissolved.

After the A liquid was added to the B liquid and stirred and mixed, the pressure was increased to 500 kgf / cm ² using a high-pressure homogenizer (manufactured by Yoshida Kikai Kogyo Co., Ltd.) equipped with a through-type chamber having a fine flow path. The dispersion treatment was repeated 6 times to obtain a coating solution for forming a charge transport layer. This charge transport layer forming coating solution is supplied at a liquid temperature of 32 ° C. and a circulation flow rate of 1.7 L / min from the supply port at the bottom of the coating tank as shown in FIG. 2, and is circulated so as to overflow from the upper edge. Then, dip coating was performed on the charge generation layer. Thereafter, it was dried at 120 ° C. for 40 minutes to obtain a charge transport layer having a thickness of 20 μm.

With respect to the electrophotographic photoreceptor thus produced, the scattered light intensity ratio (ΔI) was measured by the following method.
A xenon lamp manufactured by Hamamatsu Photonics Co., Ltd. is used as the light source, and the light emitted from the xenon lamp is converted into parallel light having a light beam area of 10 mm ² using a plano-convex synthetic quartz lens manufactured by Sigma Koki Co., Ltd. Irradiation was performed while scanning the entire image forming region (circumferential direction and axial direction) of the electrophotographic photosensitive member perpendicular to the surface of the photosensitive member. The scattered light intensity was measured with a high-sensitivity thermal differential sensor manufactured by Coherent Japan, which was arranged so as to have a constant angle of 30 ° with respect to the irradiation light and a fixed distance (50 mm) from the irradiation position. At this time, the positions of the xenon lamp and the high-sensitivity thermal differential sensor are fixed, and the xenon lamp is applied to the entire image forming area on the surface of the photoconductor by rotation and movement of the electrophotographic photoconductor. The light was scanned relatively. Further, a maximum value and a minimum value obtained by scanning the entire image forming area of the photosensitive member with parallel irradiation light from a xenon lamp are calculated, and a value obtained by dividing the minimum scattered light intensity value by the maximum scattered light intensity value (ΔI) Asked.

  Next, using DocuCentre-III C3300 manufactured by Fuji Xerox Co., Ltd., using A4 size plain paper (P paper, manufactured by Fuji Xerox), continuous printing of 100,000 sheets was performed with the short side direction as the paper running direction, and an image density of 30 % Halftone image quality was printed, and the halftone density unevenness was evaluated. Density spectrometer manufactured by X-Rite was used for density unevenness measurement, and evaluation was performed by obtaining a color difference (ΔE).

(Example 2)
In Example 1, the charge transport layer was formed in the same manner except that the temperature of the coating solution for forming the charge transport layer was 30 ° C., and the ΔI and halftone density unevenness evaluation was performed.

(Example 3)
In Example 1, the charge transport layer was formed in the same manner except that the circulation flow rate of the charge transport layer forming coating solution was 3.5 L / min, and the ΔI and the halftone density unevenness evaluation were performed.

(Example 4)
In Example 1, the charge transport layer was formed in the same manner except that the temperature of the charge transport layer forming coating solution was 30 ° C., and the circulation flow rate of the charge transport layer forming coating solution was 3.5 L / min. ΔI and halftone density unevenness were evaluated.

(Example 5)
In Example 1, the charge transport layer was formed by the same method except that the temperature of the charge transport layer forming coating solution was 28 ° C., and the circulation flow rate of the charge transport layer forming coating solution was 3.5 L / min. ΔI and halftone density unevenness were evaluated.

(Example 6)
In Example 1, the charge transport layer was formed in the same manner except that the temperature of the charge transport layer forming coating solution was 25 ° C., and the circulation flow rate of the charge transport layer forming coating solution was 3.5 L / min. ΔI and halftone density unevenness were evaluated.

(Example 7)
In Example 1, the charge transport layer was formed by the same method except that the circulation flow rate of the charge transport layer forming coating solution was 7.0 L / min, and the ΔI and halftone density unevenness evaluation were performed.

(Example 8)
In Example 1, the charge transport layer was formed in the same manner except that the temperature of the charge transport layer forming coating solution was 30 ° C., and the circulation flow rate of the charge transport layer forming coating solution was 7.0 L / min. ΔI and halftone density unevenness were evaluated.

Example 9
In Example 1, the charge transport layer was formed in the same manner except that the temperature of the charge transport layer forming coating solution was 28 ° C., and the circulation flow rate of the charge transport layer forming coating solution was 7.0 L / min. ΔI and halftone density unevenness were evaluated.

(Example 10)
In Example 1, the charge transport layer was formed in the same manner except that the temperature of the charge transport layer forming coating solution was 25 ° C., and the circulation flow rate of the charge transport layer forming coating solution was 7.0 L / min. ΔI and halftone density unevenness were evaluated.

(Comparative Example 1)
In Example 1, the charge transport layer was formed in the same manner except that the temperature of the coating liquid for forming the charge transport layer was 28 ° C., and the ΔI and the halftone density unevenness evaluation were performed.

(Comparative Example 2)
In Example 1, the charge transport layer was formed in the same manner except that the circulation flow rate of the charge transport layer forming coating solution was 1.2 L / min, and the ΔI and halftone density unevenness evaluation were performed.

(Comparative Example 3)
In Example 1, the charge transport layer was formed in the same manner except that the temperature of the coating liquid for forming the charge transport layer was 30 ° C. and the circulation flow rate was 1.2 L / min, and ΔI and halftone density unevenness evaluation Went.

(Comparative Example 4)
In Example 1, the charge transport layer was formed in the same manner except that the temperature of the coating liquid for forming the charge transport layer was 28 ° C. and the circulation flow rate was 1.2 L / min, and ΔI and halftone density unevenness evaluation Went.

(Comparative Example 5)
In Example 1, the charge transport layer was formed by the same method except that the circulation flow rate of the charge transport layer forming coating solution was 0.7 L / min, and the ΔI and halftone density unevenness evaluations were performed.

(Comparative Example 6)
In Example 1, the charge transport layer was formed in the same manner except that the temperature of the coating liquid for forming the charge transport layer was 30 ° C. and the circulation flow rate was 0.7 L / min, and the evaluation of ΔI and halftone density unevenness was performed. Went.

(Comparative Example 7)
In Example 1, the charge transport layer was formed in the same manner except that the temperature of the coating liquid for forming the charge transport layer was 28 ° C. and the circulation flow rate was 0.7 L / min, and the evaluation of ΔI and halftone density unevenness was performed. Went.

(Comparative Example 8)
In Example 1, the charge transport layer was formed by the same method except that the temperature of the coating liquid for forming the charge transport layer was 25 ° C. and the circulation flow rate was 1.7 L / min, and the ΔI and halftone density unevenness evaluation were performed. Went.

(Comparative Example 9)
In Example 1, the charge transport layer was formed in the same manner except that the temperature of the coating liquid for forming the charge transport layer was 25 ° C. and the circulation flow rate was 1.2 L / min, and ΔI and halftone density unevenness evaluation Went.

(Comparative Example 10)
In Example 1, the charge transport layer was formed by the same method except that the temperature of the coating liquid for forming the charge transport layer was 25 ° C. and the circulation flow rate was 0.7 L / min, and ΔI and halftone density unevenness evaluation Went.

The results of ΔI are shown in Table 1, and the density unevenness (color difference ΔE) measurement results are shown in Table 2. The relationship between ΔE and halftone density unevenness evaluation determination in Table 2 is as follows.
○: ΔE ≦ 1.0
Δ: 1.0 <ΔE ≦ 3.0
×: 3.0 <ΔE

1, 1a, 1b, 1c, 1d electrophotographic photosensitive member, 2 support, 3 photosensitive layer, 4 undercoat layer, 5 charge generation layer, 6 charge transport layer, 51 support (application object), 53 coating tank, 54 coating film, 55 supply port, 56 receiving section, 200 image forming apparatus, 208 charging apparatus, 210 exposure apparatus, 211 developing apparatus, 212 transfer apparatus, 213 toner removing apparatus, 214 static eliminator, 215 fixing apparatus, 220 image forming apparatus , 300 process cartridge, 404a, 404b, 404c, 404d developing device, 500 medium to be transferred

Claims (4)

A conductive support, and a photosensitive layer disposed on the conductive support,
The photosensitive layer includes fluorine-containing resin particles, a methacrylic copolymer having a structure represented by the following general formulas (I) and (II), and a charge transport material,
When the light having a wavelength of not less than 300 nm and not more than 1000 nm is collected and irradiated while scanning a region perpendicular to the surface of the photosensitive layer and forming a latent image on the photosensitive layer, the irradiated light An electrophotographic photosensitive member satisfying ΔI ≧ 0.9 by a value ΔI obtained by dividing the minimum value of scattered light intensity when the light is scattered on the surface of the photosensitive layer by the maximum value of scattered light intensity.

(In the general formulas (I) and (II), l, m, and n each independently represent a positive number of 1 or more, and p, q, r, and s each independently represent 0 or a positive number of 1 or more. T represents a positive number less than 8, R ¹ , R ² , R ³ , R ⁴ each independently represents a hydrogen atom or an alkyl group, X represents an alkylene chain, a halogen-substituted alkylene chain, —S—, —O—, —NH—, or a single bond, Y represents an alkylene chain, a halogen-substituted alkylene chain, — (C _z H _2z-1 (OH)) —, or a single bond, and — (C _z H _2z Z in _-1 (OH))-represents a positive number of 1 or more.) Preparing a liquid containing fluorine-containing resin particles, a methacrylic copolymer having a structure represented by the following general formulas (I) and (II), and a charge transporting material;
While the liquid is supplied from the bottom of the coating tank and overflows from the upper edge, the temperature T [° C.] of the liquid and the circulating flow rate F [L of the liquid are applied when the object including the conductive support is dip coated. / Minute] under the condition of satisfying T × F ≧ 50, a step of forming a coating film on the surface of the object to be coated by dip coating with the liquid;
Drying the coating film formed on the surface of the object to be coated to form a photosensitive layer;
A process for producing an electrophotographic photoreceptor comprising:

(In the general formulas (I) and (II), l, m, and n each independently represent a positive number of 1 or more, and p, q, r, and s each independently represent 0 or a positive number of 1 or more. T represents a positive number less than 8, R ¹ , R ² , R ³ , R ⁴ each independently represents a hydrogen atom or an alkyl group, X represents an alkylene chain, a halogen-substituted alkylene chain, —S—, —O—, —NH—, or a single bond, Y represents an alkylene chain, a halogen-substituted alkylene chain, — (C _z H _2z-1 (OH)) —, or a single bond, and — (C _z H _2z Z in _-1 (OH))-represents a positive number of 1 or more.)   A process cartridge comprising the electrophotographic photosensitive member according to claim 1. An electrophotographic photoreceptor according to claim 1;
A charging device for charging the electrophotographic photosensitive member;
An electrostatic latent image forming apparatus for exposing the charged electrophotographic photosensitive member to form an electrostatic latent image;
A developing device for developing the electrostatic latent image formed on the electrophotographic photosensitive member with a developer containing toner to form a toner image;
A transfer device for transferring the toner image formed on the electrophotographic photosensitive member to a transfer medium;
An image forming apparatus comprising:

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