JP7146459B2 - Electrophotographic photoreceptor, process cartridge and electrophotographic apparatus - Google Patents

Description

The present invention relates to an electrophotographic photoreceptor, a process cartridge having the electrophotographic photoreceptor, and an electrophotographic apparatus.

2. Description of the Related Art In recent years, electrophotographic apparatuses are required to mass-produce high-quality printed matter.
Therefore, an electrophotographic photoreceptor (hereinafter also referred to as a "photoreceptor") that is repeatedly used in an electrophotographic apparatus is required to have excellent electrical properties during repeated use and to have a constant image quality of output images.
Patent Document 1 describes a technique for suppressing density unevenness and ghosts in halftone images by incorporating two types of zinc oxide particles having different specific surface areas into an undercoat layer of an electrophotographic photoreceptor.

JP 2015-184494 A

According to studies by the present inventors, the electrophotographic photoreceptor described in Patent Document 1 outputs a low-density halftone image when repeatedly used for a long period of time (when about 200,000 sheets are printed) in a low-temperature, low-humidity environment. In some cases, image defects in the form of uneven streaks in the longitudinal direction (perpendicular to the circumferential direction) of the electrophotographic photosensitive member due to uneven charging (hereinafter referred to as "horizontal charging streaks") have become a problem.
Further, in the electrophotographic photoreceptor described in Patent Document 1, when repeatedly used for a long period of time in a low-temperature and low-humidity environment (when about 200,000 sheets are printed), black spot-like image defects (hereinafter "black spots") appear in the output image. ) may occur.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an electrophotographic photoreceptor that suppresses the occurrence of charging horizontal streaks and black spots when repeatedly used for a long period of time in a low-temperature, low-humidity environment.

Another object of the present invention is to provide a process cartridge and an electrophotographic apparatus having the above electrophotographic photoreceptor.

該下引き層中の全酸化亜鉛粒子の含有量の合計が、該下引き層中の該結着樹脂に対して、２００質量％以上３５０質量％以下であり、該下引き層中の該酸化亜鉛粒子（Ｐ２）および該酸化亜鉛粒子（Ｐ１）の含有量の合計が、該下引き層中の酸化亜鉛粒子の全含有量に対して、５０個数％以上１００個数％以下であり、該下引き層中の該酸化亜鉛粒子（Ｐ１）の含有量が、該下引き層中の該酸化亜鉛粒子（Ｐ２）および該酸化亜鉛粒子（Ｐ１）の含有量の合計に対して、５個数％以上６０個数％以下であり、該下引き層における該酸化亜鉛粒子（Ｐ２）の粒径の最頻値と、該酸化亜鉛粒子（Ｐ１）の粒径の最頻値との差が、１０ｎｍ以上である、ことを特徴とする。 The above objects are achieved by the present invention described below. That is, the electrophotographic photoreceptor according to the present invention has a support, an undercoat layer, and a photosensitive layer in this order, and the undercoat layer contains a binder resin and has a particle size of 20 nm or more and 40 nm or less. Zinc oxide particles (P1) , zinc oxide particles (P2) having a particle size in the range of 45 nm or more and 65 nm or less , and a benzophenone derivative , wherein the benzophenone derivative is a compound represented by the following formula (1),

The total content of zinc oxide particles in the undercoat layer is 200% by mass or more and 350% by mass or less with respect to the binder resin in the undercoat layer, and the oxidation The total content of the zinc particles (P2) and the zinc oxide particles (P1) is 50% by number or more and 100% by number or less with respect to the total content of the zinc oxide particles in the undercoat layer; The content of the zinc oxide particles (P1) in the undercoat layer is 5% by number or more with respect to the total content of the zinc oxide particles (P2) and the zinc oxide particles (P1) in the undercoat layer. 60% by number or less, and the difference between the mode of the particle size of the zinc oxide particles (P2) in the undercoat layer and the mode of the particle size of the zinc oxide particles (P1) is 10 nm or more. It is characterized by

According to the present invention, it is possible to provide an electrophotographic photoreceptor capable of suppressing the occurrence of charging horizontal streaks and the occurrence of black spots when repeatedly used for a long period of time in a low-temperature and low-humidity environment.

1 is a diagram showing an example of the layer structure of the electrophotographic photoreceptor of the present invention; FIG. 1 is a diagram showing an example of an electrophotographic apparatus equipped with a process cartridge having the electrophotographic photoreceptor of the present invention; FIG. It is a figure which shows one example of the grinder using an abrasive sheet. (a): It is a top view which shows the mold used in the manufacturing example of the electrophotographic photosensitive member. (b): A cross-sectional view of the convex portion of the mold shown in FIG. 4(a) taken along the line BB. (c): A CC cross-sectional view of the projection in the mold shown in FIG. 4(a). FIG. 2 is a diagram showing an example of a pressure contact shape transfer processing apparatus for forming recesses on the peripheral surface of an electrophotographic photosensitive member;

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below with reference to preferred embodiments.
The electrophotographic photoreceptor of the present invention is an electrophotographic photoreceptor comprising a support, an undercoat layer formed on the support, and a photosensitive layer formed on the undercoat layer.

In the charging process of the photoreceptor drum, a method of charging the photoreceptor by generating discharge in the gap between the charging member and the photoreceptor is widely used. When used (when about 200,000 sheets were printed), there were cases where charging horizontal streaks and black spots occurred in the output of low-density halftone images.
In particular, in the case of a roller-type contact charging system in which a charging roller, which is a roller-type charging member, is brought into contact with the surface of an electrophotographic photosensitive member to charge the electrophotographic photosensitive member, it has been found that charging horizontal streaks are likely to occur.

As a result of studies by the present inventors, it was found that the undercoat layer of an electrophotographic photoreceptor contains a binder resin and zinc oxide particles having a specific particle size in a specific ratio, so that the photoreceptor can be used for a long time in a low-temperature and low-humidity environment. It was found that the generation of charged horizontal streaks and black spots can be suppressed when the toner is used repeatedly for a period of time.

Specifically, the undercoat layer contains zinc oxide particles (P1) having a particle size in the range of 20 nm or more and 40 nm or less and zinc oxide particles (P2) having a particle size in the range of 45 nm or more and 65 nm or less. , in the undercoat layer, the ratio of the content of all the zinc oxide particles to the binder resin is 200% by mass or more and 350% by mass or less, and the content of the zinc oxide particles (P1) in the undercoat layer is It has been found that the above effects can be obtained when the total content (P1+P2) of the zinc oxide particles (P2) and the zinc oxide particles (P1) in the undercoat layer is 5% by number or more and 60% by number or less. rice field.

Furthermore, in order to sufficiently obtain the above effect, the content of the zinc oxide particles (P1) and the zinc oxide particles (P2) with respect to the total content (Ptotal) of the zinc oxide particles contained in the undercoat layer The total is 50% by number or more and 100% by number or less, and the difference between the mode of the particle size of the zinc oxide particles (P1) and the mode of the particle size of the zinc oxide particles (P2) is 10 nm or more. was found to be necessary.

Furthermore, the content of the zinc oxide particles (P1) in the undercoat layer is 10% by number or more with respect to the total content of the zinc oxide particles (P2) and the zinc oxide particles (P1) in the undercoat layer. It is more preferably 50% by number or less.
Furthermore, the total content of the zinc oxide particles (P2) and the zinc oxide particles (P1) in the undercoat layer is 75% by number or more and 100 particles with respect to the total content of the zinc oxide particles in the undercoat layer. % or less is more preferable.

Information on the particle size and number of zinc oxide particles contained in the undercoat layer was measured using an FIB-SEM.
Also, the ratio of the resin contained in the undercoat layer to the zinc oxide particles was calculated from the change in mass when the undercoat layer was taken out and subjected to heat treatment.

The present inventors presume as follows about the mechanism by which the occurrence of charging horizontal streaks is suppressed when the photoreceptor is repeatedly used for a long period of time. In the charging process of an electrophotographic photosensitive member, among the regions in which the surface of the electrophotographic photosensitive member is charged by the discharge from the charging member, the front side of the charging member with respect to the rotation direction of the photosensitive member is called the charging region upstream. The area on the opposite side will be called the charging area downstream. At this time, when the portion of the surface of the electrophotographic photosensitive member to which charges have been applied by the discharge on the upstream side of the charging region reaches the downstream side of the charging region, the discharge may occur non-uniformly. As a result, a potential difference occurs on the surface of the electrophotographic photosensitive member (uneven charging), which is considered to be the cause of streak-like image defects (horizontal charging streaks) in the direction perpendicular to the circumferential direction of the surface of the electrophotographic photosensitive member. ing.

The present inventors have found that the undercoat layer contains zinc oxide particles having a specific particle diameter and a binder resin in a specific ratio, thereby optimizing the conductive paths in the undercoat layer and achieving the charging region. It is believed that the portion on the surface of the electrophotographic photosensitive member charged in the upstream causes a large potential attenuation compared to the conventional photosensitive member before it reaches the charging region downstream. As a result, it is believed that the photoreceptor is uniformly charged and horizontal charging streaks are suppressed by the generation of an overall uniform discharge downstream of the charging region. It is believed that this is the reason why even after long-term repeated use in a low-temperature and low-humidity environment, the effect of suppressing charging horizontal streaks is obtained.

In addition, the present inventors speculate as follows about the mechanism by which the occurrence of black spots is suppressed when the photoreceptor is repeatedly used for a long period of time in a low-temperature and low-humidity environment. It is thought that the influence of deterioration due to the application of electricity to the photoreceptor differs depending on the state of formation of the conductive paths in the undercoat layer. By containing the resin in a specific ratio, the conductive path in the undercoat layer is optimized, so that when repeatedly used for a long period of time in a low-temperature and low-humidity environment, deterioration of the photoreceptor due to energization is suppressed. It is believed that the occurrence of black spots is suppressed.

It is believed that the effects of the present invention can be achieved by synergistic effects of the constituents of the undercoat layer of the electrophotographic photoreceptor as in the mechanism described above.

[Electrophotographic photoreceptor]
The electrophotographic photoreceptor of the present invention has, for example, an undercoat layer on a support and a photosensitive layer on the undercoat layer, as shown in FIG. In FIG. 1, 1-1 is a support, 1-2 is an undercoat layer, and 1-3 is a photosensitive layer.

Examples of the method for producing the electrophotographic photoreceptor of the present invention include a method of preparing a coating solution for each layer, which will be described later, coating the desired layers in order, and drying. At this time, the method of applying the coating liquid includes dip coating, spray coating, inkjet coating, roll coating, die coating, blade coating, curtain coating, wire bar coating, ring coating, and the like. Among these, dip coating is preferable from the viewpoint of efficiency and productivity.

<Support>
The electrophotographic photoreceptor of the present invention preferably has a support, and the support is preferably a conductive support having electrical conductivity. Further, the shape of the support includes a cylindrical shape, a belt shape, a sheet shape, and the like. Among them, a cylindrical support is preferable. Further, the surface of the support may be subjected to electrochemical treatment such as anodization, blasting treatment, cutting treatment, or the like.

The material of the support is preferably metal, resin, glass, or the like.
Examples of metals include aluminum, iron, nickel, copper, gold, stainless steel, and alloys thereof. Among them, an aluminum support using aluminum is preferable.
Conductivity may be imparted to the resin or glass by treatment such as mixing or coating with a conductive material.

<Undercoat layer>
In the present invention, an undercoat layer is provided on the support.
As described above, the undercoat layer of the electrophotographic photoreceptor of the present invention contains a binder resin and zinc oxide particles having a specific particle size in a specific ratio. Regarding the BET specific surface area of zinc oxide particles, zinc oxide particles having a BET specific surface area of 16 m ² /g or more and 21 m ² /g or less and BET specific surface areas of 27 m ² /g or more and 38 m ² /g or less. It is preferable to use a mixture of zinc oxide particles. The zinc oxide particles used in the undercoat layer of the present invention may be surface-treated as necessary. Various methods are known as surface treatment methods. For example, a method in which a surface treatment agent is adsorbed or reacted on the surface of zinc oxide particles for surface treatment, a method in which zinc oxide particles are exposed to a steam atmosphere and subjected to humidification treatment, and the like are known. can be mentioned. These surface treatment methods may be used in combination.

When using a surface treatment agent, a silane coupling agent can be suitably used as the surface treatment agent.
Examples of silane coupling agents include, for example, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, (phenylaminomethyl)methyldimethoxysilane, N-2- (Aminoethyl)-3-aminoisobutylmethyldimethoxysilane, N-ethylaminoisobutylmethyldiethoxysilane, N-methylaminopropylmethyldimethoxysilane, vinyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-(2- aminoethyl)-3-aminopropyltrimethoxysilane, methyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-chloropropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane Silane etc. are mentioned. Among these, an aminosilane coupling agent having an amino group can be particularly preferably used.

The zinc oxide particles (P1) and zinc oxide particles (P2) used in the present invention may be treated with the same surface treatment agent, or may be treated with different surface treatment agents or surface treatment methods. good. Moreover, the zinc oxide particles (P1) and the zinc oxide particles (P2) may have the same or different surface treatment amounts.

When the zinc oxide particles (P1) and zinc oxide particles (P2) of the present invention are subjected to the humidification treatment, the method is arbitrary, but the zinc oxide particles are exposed to an atmosphere containing water vapor at room temperature for a certain period of time. and a method in which the zinc oxide particles are left exposed in a constant temperature bath adjusted to high temperature and high humidity.

When the zinc oxide particles are subjected to both surface treatment with a silane coupling agent or the like and humidification treatment, either treatment may be performed first. For example, after first surface-treating the surface of the zinc oxide particles with an aminosilane coupling agent, the surface-treated zinc oxide particles are placed in an environment at a temperature of 40° C. or higher and 60° C. or lower and a humidity of 80% RH or higher and 95% RH or lower for 24 hours. A method of moistening treatment by exposing and leaving for a period of 360 hours or less can be mentioned.

Binder resins used in the undercoat layer of the present invention include polyester resins, polycarbonate resins, polyvinyl acetal resins, acrylic resins, epoxy resins, melamine resins, polyurethane resins, phenol resins, polyvinyl phenol resins, alkyd resins, and polyvinyl alcohol resins. , polyethylene oxide resin, polypropylene oxide resin, polyamide resin, polyamic acid resin, polyimide resin, polyamideimide resin, cellulose resin, and the like. Alternatively, a composition containing a monomer having a polymerizable functional group may be polymerized and used as a binder resin to form an undercoat layer as a cured film. The polymerizable functional group possessed by the monomer having a polymerizable functional group includes an isocyanate group, a blocked isocyanate group, a methylol group, an alkylated methylol group, an epoxy group, a metal alkoxide group, a hydroxyl group, an amino group, a carboxyl group, a thiol group, Carboxylic anhydride groups, carbon-carbon double bond groups, and the like.

In addition, the undercoat layer may further contain an electron transporting substance, a conductive polymer, and the like for the purpose of enhancing electrical properties.

Examples of electron-transporting substances include quinone compounds, imide compounds, benzimidazole compounds, cyclopentadienylidene compounds, fluorenone compounds, xanthone compounds, benzophenone compounds, cyanovinyl compounds, halogenated aryl compounds, silole compounds, and boron-containing compounds. . Among them, benzophenone compounds can be preferably used. An electron transporting substance having a polymerizable functional group may be used as the electron transporting substance, and an undercoat layer may be formed as a cured film by copolymerizing the electron transporting substance with the above-mentioned monomer having a polymerizable functional group.

Examples of conductive polymers include polyaniline, polypyrrole, and polythiophene.

The undercoat layer may further contain organic resin particles or a leveling agent for the purpose of adjusting the surface roughness of the undercoat layer or reducing cracks in the undercoat layer. As the organic resin particles, hydrophobic organic resin particles such as silicone particles and hydrophilic organic resin particles such as crosslinked polymethyl methacrylate (PMMA) particles can be used. In particular, when PMMA particles are used, the adhesion to the charge generation layer formed on the undercoat layer is improved, and potential fluctuation during repeated use of the photoreceptor can be suppressed.
Examples of leveling agents include silicone oil and fluorine-based oil.

The average film thickness of the undercoat layer is preferably 0.1 μm or more and 50 μm or less, more preferably 15 μm or more and 40 μm or less.

The undercoat layer can be formed by preparing an undercoat layer coating solution containing each of the materials and solvents described above, forming this coating film on a support, and drying and/or curing the coating film. Solvents used in the coating liquid include alcohol solvents, ketone solvents, ether solvents, ester solvents, aromatic hydrocarbon solvents and the like.

<Photosensitive layer>
The electrophotographic photoreceptor of the present invention has a photosensitive layer on the undercoat layer.
The photosensitive layer of the electrophotographic photoreceptor is mainly classified into (1) laminated photosensitive layer and (2) single layer photosensitive layer. (1) The laminated photosensitive layer has a charge generation layer containing a charge generation substance and a charge transport layer containing a charge transport substance. (2) The single-layer type photosensitive layer is a photosensitive layer containing both a charge-generating substance and a charge-transporting substance.

(1) Laminated photosensitive layer The laminated photosensitive layer has a charge generation layer and a charge transport layer.

(1-1) Charge Generation Layer The charge generation layer preferably contains a charge generation substance and a resin.

Examples of charge-generating substances include azo pigments, perylene pigments, polycyclic quinone pigments, indigo pigments, and phthalocyanine pigments. Among these, azo pigments and phthalocyanine pigments are preferred. Among the phthalocyanine pigments, oxytitanium phthalocyanine pigments, chlorogallium phthalocyanine pigments, and hydroxygallium phthalocyanine pigments are preferred.

The content of the charge-generating substance in the charge-generating layer is preferably 40% by mass or more and 85% by mass or less, more preferably 60% by mass or more and 80% by mass or less, relative to the total mass of the charge-generating layer. preferable.

Resins include polyester resins, polycarbonate resins, polyvinyl acetal resins, polyvinyl butyral resins, acrylic resins, silicone resins, epoxy resins, melamine resins, polyurethane resins, phenol resins, polyvinyl alcohol resins, cellulose resins, polystyrene resins, and polyvinyl acetate resins. , polyvinyl chloride resin, and the like. Among these, polyvinyl butyral resin is more preferable.

The charge generation layer may further contain additives such as antioxidants and UV absorbers. Specific examples include hindered phenol compounds, hindered amine compounds, sulfur compounds, phosphorus compounds, benzophenone compounds, and the like.

The average film thickness of the charge generation layer is preferably 0.1 μm or more and 1 μm or less, more preferably 0.15 μm or more and 0.4 μm or less.

The charge-generating layer can be formed by preparing a charge-generating layer coating solution containing each of the above materials and a solvent, forming this coating film on the undercoat layer, and drying it. Solvents used in the coating liquid include alcohol solvents, sulfoxide solvents, ketone solvents, ether solvents, ester solvents, aromatic hydrocarbon solvents and the like.

(1-2) Charge Transport Layer The charge transport layer preferably contains a charge transport substance and a resin.

Examples of charge-transporting substances include polycyclic aromatic compounds, heterocyclic compounds, hydrazone compounds, styryl compounds, enamine compounds, benzidine compounds, triarylamine compounds, and resins having groups derived from these substances. be done. Among these, triarylamine compounds and benzidine compounds are preferred.

The content of the charge transport substance in the charge transport layer is preferably 25% by mass or more and 70% by mass or less, more preferably 30% by mass or more and 55% by mass or less, relative to the total mass of the charge transport layer. preferable.

Examples of resins include polyester resins, polycarbonate resins, acrylic resins, and polystyrene resins. Among these, polycarbonate resins and polyester resins are preferred. A polyarylate resin is particularly preferable as the polyester resin.

The content ratio (mass ratio) of the charge transport substance and the resin is preferably 4:10 to 20:10, more preferably 5:10 to 12:10.

The charge transport layer may also contain additives such as antioxidants, ultraviolet absorbers, plasticizers, leveling agents, slipperiness agents and wear resistance improvers. Specifically, hindered phenol compounds, hindered amine compounds, sulfur compounds, phosphorus compounds, benzophenone compounds, siloxane-modified resins, silicone oils, fluororesin particles, polystyrene resin particles, polyethylene resin particles, silica particles, alumina particles, boron nitride particles. etc.

The average film thickness of the charge transport layer is preferably 5 μm or more and 50 μm or less, more preferably 8 μm or more and 40 μm or less, and particularly preferably 10 μm or more and 30 μm or less.

The charge-transporting layer can be formed by preparing a charge-transporting-layer coating solution containing each of the materials and solvents described above, forming this coating film on the charge-generating layer, and drying the coating film. Solvents used in the coating liquid include alcohol solvents, ketone solvents, ether solvents, ester solvents, and aromatic hydrocarbon solvents. Among these solvents, ether solvents and aromatic hydrocarbon solvents are preferred.

(2) Single-layer type photosensitive layer A single-layer type photosensitive layer is prepared by preparing a photosensitive layer coating solution containing a charge generating substance, a charge transporting substance, a resin and a solvent, and forming this coating film on the undercoat layer, It can be formed by drying. The charge-generating substance, charge-transporting substance, and resin are the same as those exemplified in the above “(1) Laminated photosensitive layer”.

<Protective layer>
In the present invention, a protective layer may be provided on the photosensitive layer. Durability can be improved by providing a protective layer.

The protective layer preferably contains conductive particles and/or a charge transport material and a resin.
Conductive particles include particles of metal oxides such as titanium oxide, zinc oxide, tin oxide, and indium oxide.
Charge-transporting substances include polycyclic aromatic compounds, heterocyclic compounds, hydrazone compounds, styryl compounds, enamine compounds, benzidine compounds, triarylamine compounds, and resins having groups derived from these substances. Among these, triarylamine compounds and benzidine compounds are preferred.
Examples of resins include polyester resins, acrylic resins, phenoxy resins, polycarbonate resins, polystyrene resins, phenol resins, melamine resins, and epoxy resins. Among them, polycarbonate resins, polyester resins, and acrylic resins are preferred.

Alternatively, the protective layer may be formed as a cured film by polymerizing a composition containing a monomer having a polymerizable functional group. The reaction at that time includes thermal polymerization reaction, photopolymerization reaction, radiation polymerization reaction, and the like. Examples of the polymerizable functional group possessed by the monomer having a polymerizable functional group include an acryloyl group and a methacryloyl group. A material having charge transport ability may be used as the monomer having a polymerizable functional group.

The protective layer may contain additives such as an antioxidant, an ultraviolet absorber, a plasticizer, a leveling agent, a lubricating agent, and an abrasion resistance improver. Specifically, hindered phenol compounds, hindered amine compounds, sulfur compounds, phosphorus compounds, benzophenone compounds, siloxane-modified resins, silicone oils, fluororesin particles, polystyrene resin particles, polyethylene resin particles, silica particles, alumina particles, boron nitride particles. etc.

The average film thickness of the protective layer is preferably 0.5 μm or more and 10 μm or less, and more preferably 1 μm or more and 7 μm or less.

The protective layer can be formed by preparing a protective layer coating liquid containing the above materials and solvent, forming this coating film on the photosensitive layer, and drying and/or curing it. Solvents used in the coating liquid include alcohol solvents, ketone solvents, ether solvents, sulfoxide solvents, ester solvents, and aromatic hydrocarbon solvents.

<Surface processing of electrophotographic photoreceptor>
In the electrophotographic photoreceptor of the present invention, for the purpose of further stabilizing the behavior of cleaning means (cleaning blade) brought into contact with the electrophotographic photoreceptor, the surface layer of the electrophotographic photoreceptor is provided with concave portions or convex portions, The surface layer can be polished to impart roughness.

In the case of forming recesses, recesses can be formed on the surface of the electrophotographic photoreceptor by pressing a mold having protrusions corresponding to the recesses onto the surface of the electrophotographic photoreceptor and transferring the shape.
In the case of forming convex portions, convex portions can be formed on the surface of the electrophotographic photoreceptor by pressing a mold having concave portions corresponding to the convex portions onto the surface of the electrophotographic photoreceptor and performing shape transfer. .

When the surface layer of the electrophotographic photoreceptor is polished to provide roughness, a polishing tool is brought into contact with the electrophotographic photoreceptor, and one or both of them are relatively moved to polish the surface of the electrophotographic photoreceptor. By doing so, roughness can be imparted. Examples of the polishing tool include a polishing member comprising a base material and a layer in which abrasive grains are dispersed in a binder resin.

[Process cartridge, electrophotographic device]
The process cartridge of the present invention integrally supports the electrophotographic photosensitive member and at least one means selected from the group consisting of charging means, developing means, transfer means and cleaning means, and provides an electrophotographic apparatus. It is characterized by being detachable from the main body.

Further, the process cartridge of the present invention is characterized in that the charging means has a charging member, and the charging member and the electrophotographic photosensitive member described above are in contact with each other.

Further, the electrophotographic apparatus of the present invention is characterized by having the electrophotographic photosensitive member, charging means, exposure means, developing means and transfer means described above.

Further, in the electrophotographic apparatus of the present invention, the charging means has a charging member, the charging member and the electrophotographic photosensitive member are in contact with each other, and only a DC voltage is applied to the charging member. It is characterized by having a power source.

FIG. 2 shows an example of a schematic configuration of an electrophotographic apparatus having a process cartridge provided with an electrophotographic photosensitive member.
A cylindrical electrophotographic photosensitive member 1 is rotationally driven about a shaft 2 in the direction of the arrow at a predetermined peripheral speed. The surface of the electrophotographic photosensitive member 1 is charged to a predetermined positive or negative potential by charging means 3 . Although the drawing shows a roller charging method using a roller-type charging member, other charging methods may be employed. In the case of the roller charging method, there are a DC charging method in which only a DC voltage is applied to the roller-type charging member, and an AC/DC charging method in which an AC voltage is superimposed on the DC voltage. From the point of view, the DC charging method is preferable. The surface of the charged electrophotographic photosensitive member 1 is irradiated with exposure light 4 from an exposure means (not shown) to form an electrostatic latent image corresponding to desired image information. The electrostatic latent image formed on the surface of the electrophotographic photoreceptor 1 is developed with toner accommodated in the developing means 5 to form a toner image on the surface of the electrophotographic photoreceptor 1 . A toner image formed on the surface of the electrophotographic photosensitive member 1 is transferred onto a transfer material 7 by transfer means 6 . The transfer material 7 onto which the toner image has been transferred is conveyed to a fixing means 8 where the toner image is fixed and printed out of the electrophotographic apparatus. The electrophotographic apparatus may have a cleaning means 9 for removing deposits such as toner remaining on the surface of the electrophotographic photosensitive member 1 after transfer. Also, a so-called cleanerless system may be used in which the deposits are removed by developing means or the like without separately providing a cleaning means. The electrophotographic apparatus may have a charge removing mechanism for removing charges from the surface of the electrophotographic photosensitive member 1 with pre-exposure light 10 from a pre-exposure unit (not shown). Also, a guide means 12 such as a rail may be provided for attaching and detaching the process cartridge 11 of the present invention to and from the main body of the electrophotographic apparatus.

The electrophotographic photoreceptor of the present invention can be used in laser beam printers, LED printers, copiers, facsimiles, and multifunction devices thereof.

[Examples and Comparative Examples]
EXAMPLES The present invention will be described in more detail below using examples and comparative examples. The present invention is by no means limited by the following examples, as long as the gist thereof is not exceeded. In the description of the following examples, "parts" are based on mass unless otherwise specified.

[Production example of surface-treated zinc oxide particles]
<Production example of surface-treated ZnO (A)>
100 parts of zinc oxide particles (specific surface area: 30 m ² /g) were stirred and mixed with 500 parts of toluene. To this, 0.8 part of a silane coupling agent (compound name: N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, trade name: KBM602, manufactured by Shin-Etsu Chemical Co., Ltd.) was added, and the mixture was stirred for 6 hours. Stirred. After that, toluene was distilled off under reduced pressure, and the residue was dried (heat dried) at 130°C for 6 hours to obtain surface-treated zinc oxide particles ZnO (A).

<Production example of surface-treated ZnO (B)>
100 parts of zinc oxide particles (specific surface area: 19 m ² /g) were stirred and mixed with 500 parts of toluene. To this, 0.8 part of a silane coupling agent (compound name: N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, trade name: KBM602, manufactured by Shin-Etsu Chemical Co., Ltd.) was added, and the mixture was stirred for 6 hours. Stirred. Thereafter, toluene was distilled off under reduced pressure, and the residue was dried (heat dried) at 130°C for 6 hours to obtain surface-treated zinc oxide particles ZnO (B).

<Production example of surface-treated ZnO (C)>
100 parts of zinc oxide particles (specific surface area: 55 m ² /g) were stirred and mixed with 500 parts of toluene. To this, 0.8 part of a silane coupling agent (compound name: N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, trade name: KBM602, manufactured by Shin-Etsu Chemical Co., Ltd.) was added, and the mixture was stirred for 6 hours. Stirred. Thereafter, toluene was distilled off under reduced pressure, and the residue was dried (heat dried) at 130° C. for 6 hours to obtain surface-treated zinc oxide particles ZnO(C).

<Production example of surface-treated ZnO (D)>
100 parts of zinc oxide particles (specific surface area: 15 m ² /g) were stirred and mixed with 500 parts of toluene. To this, 0.8 part of a silane coupling agent (compound name: N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, trade name: KBM602, manufactured by Shin-Etsu Chemical Co., Ltd.) was added, and the mixture was stirred for 6 hours. Stirred. After that, toluene was distilled off under reduced pressure, and the particles were dried (heat dried) at 130° C. for 6 hours to obtain surface-treated zinc oxide particles ZnO (D).

<Production example of surface-treated ZnO (E)>
100 parts of zinc oxide particles (specific surface area: 28 m ² /g) were stirred and mixed with 500 parts of toluene. To this, 0.8 part of a silane coupling agent (compound name: N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, trade name: KBM602, manufactured by Shin-Etsu Chemical Co., Ltd.) was added, and the mixture was stirred for 6 hours. Stirred. Thereafter, toluene was distilled off under reduced pressure, and the residue was dried (heat dried) at 130°C for 6 hours to obtain surface-treated zinc oxide particles ZnO(E).

<Production example of surface-treated ZnO (F)>
100 parts of zinc oxide particles (specific surface area: 21 m ² /g) were stirred and mixed with 500 parts of toluene. To this, 0.8 part of a silane coupling agent (compound name: N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, trade name: KBM602, manufactured by Shin-Etsu Chemical Co., Ltd.) was added, and the mixture was stirred for 6 hours. Stirred. Thereafter, toluene was distilled off under reduced pressure, and the residue was dried (heat dried) at 130° C. for 6 hours to obtain surface-treated zinc oxide particles ZnO(F).

<Production example of surface-treated ZnO (G)>
100 parts of zinc oxide particles (specific surface area: 26 m ² /g) were stirred and mixed with 500 parts of toluene. To this, 0.8 part of a silane coupling agent (compound name: N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, trade name: KBM602, manufactured by Shin-Etsu Chemical Co., Ltd.) was added, and the mixture was stirred for 6 hours. Stirred. Thereafter, toluene was distilled off under reduced pressure, and the residue was dried (heat dried) at 130°C for 6 hours to obtain surface-treated zinc oxide particles ZnO (G).

<Production example of surface-treated ZnO (H)>
100 parts of zinc oxide particles (specific surface area: 23 m ² /g) were stirred and mixed with 500 parts of toluene. To this, 0.8 part of a silane coupling agent (compound name: N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, trade name: KBM602, manufactured by Shin-Etsu Chemical Co., Ltd.) was added, and the mixture was stirred for 6 hours. Stirred. After that, toluene was distilled off under reduced pressure, and the residue was dried (heat dried) at 130° C. for 6 hours to obtain surface-treated zinc oxide particles ZnO(H).

<Production example of surface-treated ZnO (I)>
100 parts of zinc oxide particles (specific surface area: 7.5 m ² /g) were stirred and mixed with 500 parts of toluene. To this, 0.8 part of a silane coupling agent (compound name: N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, trade name: KBM602, manufactured by Shin-Etsu Chemical Co., Ltd.) was added, and the mixture was stirred for 6 hours. Stirred. Thereafter, toluene was distilled off under reduced pressure, and the residue was dried (heat dried) at 130°C for 6 hours to obtain surface-treated zinc oxide particles ZnO (I).

<Production example of surface-treated ZnO (J)>
100 parts of zinc oxide particles (specific surface area: 32 m ² /g) were stirred and mixed with 500 parts of toluene. To this, 0.8 part of a silane coupling agent (compound name: N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, trade name: KBM602, manufactured by Shin-Etsu Chemical Co., Ltd.) was added, and the mixture was stirred for 6 hours. Stirred. Thereafter, toluene was distilled off under reduced pressure, and the residue was dried (heat dried) at 130°C for 6 hours to obtain surface-treated zinc oxide particles ZnO (J).

<Production example of surface-treated ZnO (K)>
100 parts of zinc oxide particles (specific surface area: 18 m ² /g) were stirred and mixed with 500 parts of toluene. To this, 0.8 part of a silane coupling agent (compound name: N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, trade name: KBM602, manufactured by Shin-Etsu Chemical Co., Ltd.) was added, and the mixture was stirred for 6 hours. Stirred. After that, toluene was distilled off under reduced pressure, and the residue was dried (heat dried) at 130° C. for 6 hours to obtain surface-treated zinc oxide particles ZnO(K).

<Production example of surface-treated ZnO (L)>
100 parts of zinc oxide particles (specific surface area: 35 m ² /g) were stirred and mixed with 500 g of toluene. To this, 0.5 parts of a silane coupling agent (compound name: N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, trade name: KBM602 , manufactured by Shin-Etsu Chemical Co., Ltd.) was added, and the mixture was stirred for 6 hours. Stirred. After that, toluene was distilled off under reduced pressure, and the particles were dried (heat dried) at 130° C. for 6 hours to obtain surface-treated zinc oxide particles ZnO(L).

<Production example of surface-treated ZnO (M)>
100 parts of zinc oxide particles (specific surface area: 17 m ² /g) were stirred and mixed with 500 g of toluene. To this, 1.3 parts of a silane coupling agent (compound name: N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, trade name: KBM602 , manufactured by Shin-Etsu Chemical Co., Ltd.) was added, followed by stirring for 6 hours. Stirred. After that, toluene was distilled off under reduced pressure, and the particles were dried (heat dried) at 130° C. for 6 hours to obtain surface-treated zinc oxide particles ZnO(M).

<Production example of surface-treated ZnO(N)>
100 parts of zinc oxide particles (specific surface area: 27 m ² /g) were stirred and mixed with 500 g of toluene. To this, 1.3 parts of a silane coupling agent (compound name: N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, trade name: KBM602 , manufactured by Shin-Etsu Chemical Co., Ltd.) was added, followed by stirring for 6 hours. Stirred. After that, toluene was distilled off under reduced pressure, and the particles were dried (heat dried) at 130° C. for 6 hours to obtain surface-treated zinc oxide particles ZnO(N).

<Production example of surface-treated ZnO (O)>
100 parts of zinc oxide particles (specific surface area: 20 m ² /g) were stirred and mixed with 500 g of toluene. To this, 0.8 part of a silane coupling agent (compound name: N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, trade name: KBM602 , manufactured by Shin-Etsu Chemical Co., Ltd.) was added, and the mixture was stirred for 6 hours. Stirred. Thereafter, toluene was distilled off under reduced pressure, and the particles were dried (heat dried) at 130° C. for 6 hours to obtain surface-treated zinc oxide particles ZnO(O).

<Production example of humidified ZnO(P)>
The surface-treated zinc oxide particles ZnO(A) were left exposed for 100 days in a constant temperature bath set at a temperature of 23° C. and a humidity of 50% RH to obtain humidified zinc oxide particles ZnO(P).

<Production example of humidified ZnO (Q)>
The surface-treated zinc oxide particles ZnO(B) were left exposed for 100 days in a constant temperature bath set at a temperature of 23° C. and a humidity of 50% RH to obtain humidified zinc oxide particles ZnO(Q).

<Production example of humidified ZnO (R)>
The surface-treated zinc oxide particles ZnO(A) were left exposed for 7 days in a constant temperature bath set at a temperature of 50° C. and a humidity of 95% RH to obtain humidified zinc oxide particles ZnO(R).

<Production example of humidified ZnO(S)>
The surface-treated zinc oxide particles ZnO(B) were left exposed for 7 days in a constant temperature bath set at a temperature of 50° C. and a humidity of 95% RH to obtain humidified zinc oxide particles ZnO(S).

<Example 1>
An aluminum cylinder having a length of 357.5 mm, a thickness of 0.7 mm and an outer diameter of 30 mm was prepared as a support (conductive support). The surface of the prepared aluminum cylinder was machined using a lathe.
As cutting conditions, a cutting tool with R0.1 was used, the number of revolutions of the spindle was 10000 rpm, and the cutting speed was changed continuously in the range of 0.03 to 0.06 mm/rpm.

分散処理後、シリコーンオイル（商品名：ＳＨ２８ＰＡ、東レダウコーニングシリコーン社製）０．０１部、架橋ポリメタクリル酸メチル（ＰＭＭＡ）粒子（商品名：ＴＥＣＨＰＯＬＹＭＥＲＳＳＸ－１０２、積水化成品工業（株）製、平均一次粒径：２．５μｍ）を５．６部加えて攪拌することによって、下引き層用塗布液を調製した。
この下引き層用塗布液を上記支持体上に浸漬塗布して塗膜を形成し、この塗膜を４０分間１６０℃で乾燥（加熱乾燥）させて、膜厚が３０μｍの下引き層を形成した。 Next, butyral resin (trade name: BM-1, manufactured by Sekisui Chemical Co., Ltd.) 15 parts and blocked isocyanate (trade name: Sumidur 3175, manufactured by Sumitomo Bayern Urethane Co., Ltd., non-volatile component 75%) 20 parts, A solution was obtained by dissolving in a mixed solvent of 65 parts of methyl ethyl ketone and 65 parts of 1-butanol. To this solution, 12 parts of the surface-treated zinc oxide particles ZnO (A), 69 parts of the surface-treated zinc oxide particles ZnO (B), and 0 of a compound represented by the following formula (1) (benzophenone derivative) 4 parts (manufactured by Tokyo Kasei Kogyo Co., Ltd.) was added, placed in a sand mill apparatus using glass beads with a diameter of 0.8 mm, and subjected to dispersion treatment in an atmosphere of 23±3° C. for 3 hours.

After dispersion treatment, silicone oil (trade name: SH28PA, manufactured by Dow Corning Toray Silicone Co., Ltd.) 0.01 part, crosslinked polymethyl methacrylate (PMMA) particles (trade name: TECHPOLYMERSSX-102, manufactured by Sekisui Plastics Co., Ltd., An undercoat layer coating solution was prepared by adding 5.6 parts of an average primary particle size of 2.5 μm and stirring.
This undercoat layer coating liquid is dip-coated on the support to form a coating film, and this coating film is dried (heat dried) at 160° C. for 40 minutes to form an undercoat layer having a thickness of 30 μm. did.

Next, 20 parts of a crystalline hydroxygallium phthalocyanine crystal (charge-generating substance) having strong peaks at 7.4° and 28.2° of Bragg angles 2θ ± 0.2° in CuKα characteristic X-ray diffraction, the following formula ( A) 0.2 parts of the calixarene compound represented by A), 10 parts of polyvinyl butyral resin (trade name: S-lec BX-1, manufactured by Sekisui Chemical Co., Ltd.), and 600 parts of cyclohexanone, using glass beads with a diameter of 1 mm The mixture was placed in a sand mill, subjected to dispersion treatment for 4 hours, and then 600 parts of ethyl acetate was added to prepare a coating liquid for charge generation layer.
This charge generation layer coating liquid was applied onto the undercoat layer by dip coating, and the resulting coating film was dried at 80° C. for 15 minutes to form a charge generation layer having a thickness of 0.19 μm.

Next, 60 parts of a compound (charge-transporting substance) represented by the following formula (B), 30 parts of a compound (charge-transporting substance) represented by the following formula (C), and 10 parts of a compound represented by the following formula (D) (D ), polycarbonate resin (trade name: Iupilon Z400, manufactured by Mitsubishi Engineering-Plastics Co., Ltd., bisphenol Z type polycarbonate) 100 parts, polycarbonate represented by the following formula (E) (viscosity average molecular weight Mv: 20000) 0.02 parts was dissolved in a mixed solvent of 600 parts of o-xylene and 200 parts of dimethoxymethane to prepare a coating solution for charge transport layer.
The charge transport layer coating liquid was applied onto the charge generation layer by dip coating to form a coating film, and the resulting coating film was dried at 100° C. for 30 minutes to form a charge transport layer having a thickness of 18 μm. .

Next, a resin having a repeating structural unit represented by the following formula (A1) and a repeating structural unit represented by the following formula (A2) (weight average molecular weight: 130,000, copolymerization ratio (A1)/(A2) = 1 / 1 (molar ratio)) 1.65 parts, 1,1,2,2,3,3,4-heptafluorocyclopentane (trade name: Zeorora H, manufactured by Nippon Zeon Co., Ltd.) 40 parts and 1 - Dissolved in a mixed solvent of 55 parts of propanol. Thereafter, a liquid to which 30 parts of tetrafluoroethylene resin powder (trade name: Lubron L-2, manufactured by Daikin Industries, Ltd.) was added was added to a high-pressure disperser (trade name: Microfluidizer M-110EH, Microfluidics (USA) Co., Ltd.) to obtain a dispersion.
Then, 52.0 parts of the hole-transporting compound represented by the following formula (F), 16.0 parts of the compound represented by the following formula (G) (Aronix M-315, manufactured by Toagosei Co., Ltd.), the following formula ( H) compound (manufactured by Sigma-Aldrich) 2.0 parts, 0.75 parts of siloxane-modified acrylic compound (BYK-3550, manufactured by BYK-Chemie Japan Co., Ltd.), 1, 1, 2, 2, 3, 3 , 35 parts of 4-heptafluorocyclopentane and 15 parts of 1-propanol are added to the dispersion liquid, and filtered through a polyflon filter (trade name: PF-040, manufactured by Advantec Toyo Co., Ltd.) to obtain a protective layer coating liquid. was prepared.

This protective layer coating solution was applied onto the charge transport layer by dip coating, and the resulting coating film was dried at 40° C. for 5 minutes. After drying, the coating film was irradiated with an electron beam for 1.6 seconds under conditions of an acceleration voltage of 70 KV and an absorption dose of 15 kGy in a nitrogen atmosphere. After that, heat treatment was performed for 15 seconds under the condition that the temperature of the coating film became 135° C. in a nitrogen atmosphere. The oxygen concentration from the electron beam irradiation to the heat treatment for 15 seconds was 15 ppm. Next, heat treatment was performed in the air for 1 hour under the condition that the coating film was heated to 105° C. to form a protective layer having a thickness of 5 μm. In this way, an electrophotographic photoreceptor was produced before forming recesses.

Next, a mold member (mold) was installed in a press-contact shape transfer processing apparatus, and surface processing was performed on the electrophotographic photoreceptor before formation of recesses.
Specifically, the mold shown in FIG. 4 was installed in a press-contact shape transfer processing apparatus having a structure roughly shown in FIG. FIG. 4 is a diagram showing a mold used in Examples and Comparative Examples. FIG. 4(a) is a top view showing an outline of the mold, and FIG. 4(b) is a schematic cross-sectional view of the convex portion of the mold in the axial direction of the electrophotographic photosensitive member (cross-sectional view along the BB cross section in FIG. 4(a). ). FIG. 4(c) is a circumferential cross-sectional view of the projections of the mold of the electrophotographic photosensitive member (cross-sectional view taken along line CC in FIG. 4(a)). The mold shown in FIG. 4 has a maximum width (maximum width in the axial direction of the electrophotographic photosensitive member when the projections on the mold are viewed from above) X: 50 μm, a maximum length (the projections on the mold is the maximum length in the circumferential direction of the electrophotographic photosensitive member when viewed from above). Note that the area ratio is the ratio of the area of the projections to the entire surface of the mold when viewed from above. During processing, the temperatures of the electrophotographic photoreceptor and the mold were controlled so that the surface temperature of the electrophotographic photoreceptor was 120.degree. Then, while pressing the electrophotographic photosensitive member and the pressure member against the mold with a pressure of 7.0 MPa, the electrophotographic photosensitive member is rotated in the circumferential direction to form concave portions on the entire surface layer (peripheral surface) of the electrophotographic photosensitive member. formed.
As described above, the electrophotographic photoreceptor of Example 1 was produced.

[evaluation]
(Evaluation of charged horizontal streaks and black spots)
The charging horizontal streaks and black spots of the electrophotographic photosensitive member were evaluated as follows.
The evaluation was performed under an environment of temperature 15° C./humidity 10% RH.
As an evaluation apparatus, a charging device of a copier manufactured by Canon Inc. (trade name: iR-ADVC5250) was modified to a DC charging system using a charging roller and used. Then, the DC voltage and the exposure light amount are applied to the charging roller so that the initial dark potential (Vd ₀ ) of the electrophotographic photosensitive member is −900 [V] and the initial bright potential (Vl ₀ ) is −200 [V]. conditions were set.
After the photosensitive drum was mounted in the process cartridge and mounted in the evaluation apparatus, 200,000 sheets of A4 vertical size paper were printed with an image ratio of 3%.

The charging horizontal streak was evaluated as follows.
After outputting 200,000 images, after adjusting the dark area potential Vd of the electrophotographic photosensitive member to -900 [V] and the light area potential (Vl) to -200 [V], a 1-dot Keima pattern halftone image was output. did.
The density of the halftone image was adjusted to 0.100 using a spectral densitometer (trade name: X-Rite 504/508, manufactured by X-Rite Co., Ltd.). The output halftone image was visually evaluated.

The image evaluation criteria are as follows.
A: No horizontal charged streaks at all B: Slightly observed horizontal charged streaks, but at a practically acceptable level C: Horizontal charged streaks at a level that poses a practical problem is observed

Evaluation of black spots was performed as follows.
After 200,000 images were output, the dark area potential of the electrophotographic photosensitive member was adjusted to Vd of -900 [V], and then a solid white image was output.
The output solid white image was visually evaluated.

The image evaluation criteria are as follows.
A: No black spots at all B: Slight black spots observed, but at a level that poses no practical problem C: Black spots at a level that poses practical problems are observed

(Evaluation of composition of undercoat layer)
In the present invention, information on the particle size and number of zinc oxide particles in the undercoat layer was obtained as follows using the Slice & View mode of FIB-SEM (NVision 40 manufactured by SII/Zeiss).

First, the photoreceptor described in Example 1, which had been evaluated for charging horizontal streaks and black spots, was cut so as to expose the cross section of the layer of the photoreceptor to prepare an observation surface. Six observation regions were set every 5 μm from the surface of the undercoat layer toward the support (substrate) on the observation surface of the cross section of the undercoat layer. The observation surface of the cross section of the undercoat layer was sliced by a thickness of 2 μm at a slice interval of 10 nm, and image information was recorded in a range of 2 μm long×2 μm wide×2 μm thick for each observation area. The particle size was calculated for 50 randomly selected zinc oxide particles within each observation area. When the longest side of the selected primary particles is a and the shortest side is b, (a+b)/2 is taken as the grain size of the particles. The results of particle size calculation in each observation area were summed up to determine the distribution of particle size and number of zinc oxide particles in the undercoat layer.

Next, from the distribution of the particle size and the number of zinc oxide particles in the undercoat layer, zinc oxide particles (P1) having a particle size in the range of 20 nm or more and 40 nm or less and zinc oxide particles (P1) having a particle size in the range of 45 nm or more and 65 nm or less The ratio ((P1+P2)/Ptotal) of the total number of zinc oxide particles (P2) to the total number of zinc oxide particles (Ptotal) in the undercoat layer was calculated. Furthermore, the ratio (P1/(P1+P2)) of the number of the zinc oxide particles (P1) to the total number of the zinc oxide particles (P1) and the zinc oxide particles (P2) was calculated.

Further, with respect to the obtained distribution of the particle size and the number of zinc oxide particles in the undercoat layer, the particle size is divided by 2.5 nm, and the zinc oxide having a particle size in the range of 20 nm or more and 40 nm or less. The particle size mode (P1m) is calculated for the particles (P1), and the particle size mode (P1m) for the zinc oxide particles (P2) having a particle size in the range of 45 nm or more and 65 nm or less is calculated. P2m) was calculated, and the difference between the modes (P2m-P1m) was obtained. When there are multiple classes with the same number of particle sizes, in the particle size range of the zinc oxide particles (P1), the class with the largest particle size is (P1m), and in the particle size range of the zinc oxide particles (P2), The class with the smallest particle size was defined as (P2m).

In addition, after removing the layer laminated on the undercoat layer, the undercoat layer is taken out as a solid material from the photoreceptor for which the evaluation of charging horizontal streaks and black spots has been completed, and the change in mass is measured while the undercoat layer is subjected to heat treatment. Thus, the mass ratio (P/B) of all the zinc oxide particles (P) to the binder resin (B) in the undercoat layer was calculated.

<Example 2>
In Example 1, the amount of zinc oxide particles ZnO (A) used was changed from 12 parts to 2 parts, and the amount of zinc oxide particles ZnO (B) used was changed from 69 parts to 79 parts. Except for this, the same procedure as in Example 1 was repeated to prepare an undercoat layer coating solution of Example 2.
An electrophotographic photoreceptor of Example 2 was produced in the same manner as in Example 1 except that the undercoat layer coating liquid of Example 2 was used to form an undercoat layer on the support. A black spot evaluation was made, as well as an evaluation of the composition of the undercoat layer.

<Example 3>
In Example 1, the amount of zinc oxide particles ZnO (A) used was changed from 12 parts to 4 parts, and the amount of zinc oxide particles ZnO (B) used was changed from 69 parts to 77 parts. Except for this, the same procedure as in Example 1 was repeated to prepare a coating liquid for an undercoat layer of Example 3.
An electrophotographic photoreceptor of Example 3 was produced in the same manner as in Example 1 except that the undercoat layer coating liquid of Example 3 was used to form an undercoat layer on the support. A black spot evaluation was made, as well as an evaluation of the composition of the undercoat layer.

<Example 4>
In Example 1, the amount of zinc oxide particles ZnO (A) used was changed from 12 parts to 20 parts, and the amount of zinc oxide particles ZnO (B) used was changed from 69 parts to 61 parts. Except for this, the same procedure as in Example 1 was repeated to prepare an undercoat layer coating solution of Example 4.
An electrophotographic photoreceptor of Example 4 was produced in the same manner as in Example 1 except that the undercoat layer coating solution of Example 4 was used to form an undercoat layer on the support. A black spot evaluation was made, as well as an evaluation of the composition of the undercoat layer.

<Example 5>
In Example 1, the amount of zinc oxide particles ZnO (A) used was changed from 12 parts to 24 parts, and the amount of zinc oxide particles ZnO (B) used was changed from 69 parts to 57 parts. A coating solution for an undercoat layer of Example 5 was prepared in the same manner as in Example 1 except for the above.
An electrophotographic photoreceptor of Example 5 was produced in the same manner as in Example 1 except that the undercoat layer coating solution of Example 5 was used to form an undercoat layer on the support. A black spot evaluation was made, as well as an evaluation of the composition of the undercoat layer.

<Example 6>
In Example 1, the amount of zinc oxide particles ZnO (A) used was changed from 12 parts to 10 parts, and the amount of zinc oxide particles ZnO (B) used was changed from 69 parts to 63 parts. Further, 4 parts of ZnO(C) and 4 parts of ZnO(D) were added to prepare a coating solution for an undercoat layer. Except for this, the same procedure as in Example 1 was repeated to prepare an undercoat layer coating solution of Example 6.
An electrophotographic photoreceptor of Example 6 was produced in the same manner as in Example 1 except that the undercoat layer coating liquid of Example 6 was used to form an undercoat layer on the support. A black spot evaluation was made, as well as an evaluation of the composition of the undercoat layer.

<Example 7>
In Example 6, the amount of zinc oxide particles ZnO (A) used was changed from 10 parts to 8 parts, and the amount of zinc oxide particles ZnO (B) used was changed from 63 parts to 45 parts. Furthermore, the amount of ZnO(C) used was changed from 4 parts to 6 parts, and the amount of ZnO(D) used was changed from 4 parts to 22 parts. Except for this, the same procedure as in Example 6 was repeated to prepare a coating solution for an undercoat layer of Example 7.
An electrophotographic photoreceptor of Example 7 was produced in the same manner as in Example 6 except that the undercoat layer coating liquid of Example 7 was used to form an undercoat layer on the support. A black spot evaluation was made, as well as an evaluation of the composition of the undercoat layer.

<Example 8>
In Example 1, the zinc oxide particles ZnO (J) were used instead of the zinc oxide particles ZnO (A), and the zinc oxide particles ZnO (K) were used instead of the zinc oxide particles ZnO (B). A liquid was prepared. Except for this, in the same manner as in Example 1, an undercoat layer coating solution of Example 8 was prepared.
An electrophotographic photoreceptor of Example 8 was produced in the same manner as in Example 1 except that the undercoat layer coating liquid of Example 8 was used to form an undercoat layer on the support. A black spot evaluation was made, as well as an evaluation of the composition of the undercoat layer.

<Example 9>
In Example 1, the amount of butyral resin (trade name: BM-1, manufactured by Sekisui Chemical Co., Ltd.) was changed from 15 parts to 20 parts. In addition, the amount of blocked isocyanate (trade name: Sumidur 3175, manufactured by Sumitomo Bayer Urethane Co., Ltd., 75% non-volatile content) was changed from 20 parts to 27 parts. Except for this, in the same manner as in Example 1, a coating solution for an undercoat layer of Example 9 was prepared.
An electrophotographic photoreceptor of Example 9 was produced in the same manner as in Example 1 except that the undercoat layer coating liquid of Example 9 was used to form an undercoat layer on the support. A black spot evaluation was made, as well as an evaluation of the composition of the undercoat layer.

<Example 10>
In Example 1, the amount of butyral resin (trade name: BM-1, manufactured by Sekisui Chemical Co., Ltd.) was changed from 15 parts to 11.5 parts. Also, the amount of blocked isocyanate (trade name: Sumidur 3175, manufactured by Sumitomo Bayer Urethane Co., Ltd., 75% non-volatile component) was changed from 20 parts to 15.5 parts. A coating solution for an undercoat layer of Example 10 was prepared in the same manner as in Example 1 except for the above.
An electrophotographic photoreceptor of Example 10 was produced in the same manner as in Example 1 except that the undercoat layer coating solution of Example 10 was used to form an undercoat layer on the support. A black spot evaluation was made, as well as an evaluation of the composition of the undercoat layer.

<Example 11>
In Example 1, instead of using ZnO (A) and ZnO (B) as zinc oxide particles, 12 parts of ZnO (E) and 69 parts of ZnO (F) were used to prepare the undercoat layer coating liquid. prepared. Except for this, the same procedure as in Example 1 was repeated to prepare a coating liquid for an undercoat layer of Example 11.
An electrophotographic photoreceptor of Example 11 was produced in the same manner as in Example 1 except that the undercoat layer coating liquid of Example 11 was used to form an undercoat layer on the support. A black spot evaluation was made, as well as an evaluation of the composition of the undercoat layer.

<Example 12>
In Example 1, instead of zinc oxide particles ZnO (A), zinc oxide particles ZnO (A2) (specific surface area: 30 m ² /g) not subjected to silane coupling treatment, and instead of zinc oxide particles ZnO (B) A coating liquid for an undercoat layer was prepared using zinc oxide particles ZnO (B2) (specific surface area: 19 m ² /g) not subjected to silane coupling treatment. Except for this, the same procedure as in Example 1 was repeated to prepare an undercoat layer coating solution of Example 12.
An electrophotographic photoreceptor of Example 12 was produced in the same manner as in Example 1, except that an undercoat layer was formed on the support using the undercoat layer coating liquid of Example 12. A black spot evaluation was made, as well as an evaluation of the composition of the undercoat layer.

< Reference Example 13>
In Example 1, an undercoat layer coating solution was prepared without using the compound (benzophenone derivative) represented by the formula (1) (manufactured by Tokyo Kasei Kogyo Co., Ltd.).
A coating solution for an undercoat layer of Reference Example 13 was prepared in the same manner as in Example 1 except for the above.
An electrophotographic photoreceptor of Reference Example 13 was produced in the same manner as in Example 1 except that the undercoat layer coating liquid of Reference Example 13 was used to form an undercoat layer on the support. A black spot evaluation was made, as well as an evaluation of the composition of the undercoat layer.

< Reference Example 14>
In Example 12, an undercoat layer coating solution was prepared without using the compound (benzophenone derivative) represented by the formula (1) (manufactured by Tokyo Kasei Kogyo Co., Ltd.).
Otherwise, in the same manner as in Example 12, a coating solution for an undercoat layer of Reference Example 14 was prepared.
An electrophotographic photoreceptor of Reference Example 14 was produced in the same manner as in Example 12 except that the undercoat layer coating liquid of Reference Example 14 was used to form an undercoat layer on the support. A black spot evaluation was made, as well as an evaluation of the composition of the undercoat layer.

<Example 15>
20 parts of butyral resin (trade name: BM-1, manufactured by Sekisui Chemical Co., Ltd.) and 27 parts of blocked isocyanate (trade name: Sumidur 3175, manufactured by Sumitomo Bayer Urethane Co., Ltd., nonvolatile component 75%), 65 parts of methyl ethyl ketone and 65 parts of 1-butanol in a mixed solvent to obtain a solution. 3 parts of zinc oxide particles ZnO (E), 52 parts of zinc oxide particles ZnO (F), 1 part of zinc oxide particles ZnO (C), and 25 parts of zinc oxide particles ZnO (D) were added to this solution, and It was placed in a sand mill apparatus using glass beads of 0.8 mm and subjected to dispersion treatment in an atmosphere of 23±3° C. for 3 hours.
After dispersion treatment, silicone oil (trade name: SH28PA, manufactured by Dow Corning Toray Silicone Co., Ltd.) 0.01 part, crosslinked polymethyl methacrylate (PMMA) particles (trade name: TECHPOLYMERSSX-102, manufactured by Sekisui Plastics Co., Ltd., 5.6 parts of an average primary particle size of 2.5 μm) was added and stirred to prepare a coating solution for an undercoat layer of Example 15.
An electrophotographic photoreceptor of Example 15 was produced in the same manner as in Example 1 except that the undercoat layer coating liquid of Example 15 was used to form an undercoat layer on the support. A black spot evaluation was made, as well as an evaluation of the composition of the undercoat layer.

<Example 16>
In Example 1, the amount of zinc oxide particles ZnO (A) used was changed from 12 parts to 24 parts, and the amount of zinc oxide particles ZnO (B) used was changed from 69 parts to 57 parts. In addition, the amount of butyral resin (trade name: BM-1, manufactured by Sekisui Chemical Co., Ltd.) was changed from 15 parts to 11.5 parts, and blocked isocyanate (trade name: Sumidur 3175, Sumitomo Bayern Urethane Co., Ltd.) non-volatile content 75%) was changed from 20 parts to 15.5 parts. Except for this, in the same manner as in Example 1, a coating solution for an undercoat layer of Example 16 was prepared.
An electrophotographic photoreceptor of Example 16 was produced in the same manner as in Example 1, except that the undercoat layer coating liquid of Example 16 was used to form an undercoat layer on the support. A black spot evaluation was made, as well as an evaluation of the composition of the undercoat layer.

<Example 17>
In Example 1, the film thickness of the undercoat layer was changed from 30 μm to 18 μm, and the other steps up to the formation of the charge transport layer were carried out in the same manner as in Example 1.

Next, 1.5 parts of a fluorine atom-containing resin (trade name: GF-300, manufactured by Toagosei Co., Ltd.) was added to 1,1,2,2,3,3,4-heptafluorocyclopentane (trade name : Zeorora H, manufactured by Nippon Zeon Co., Ltd.) and dissolved in a mixed solvent of 45 parts of 1-propanol.
To this liquid, 30 parts of tetrafluoroethylene resin powder (trade name: Lubron L-2, manufactured by Daikin Industries, Ltd.) is added, and this liquid is dispersed in a high-pressure disperser (trade name: Microfluidizer M-110EH, rice Microfluidics Co., Ltd.) to obtain a dispersion. Then, 70 parts of the hole-transporting compound represented by Structural Formula (F), 30 parts of 1,1,2,2,3,3,4-heptafluorocyclopentane and 30 parts of 1-propanol were added to the dispersion liquid. In addition, filtration was performed using a Polyflon filter (trade name: PF-040, manufactured by Advantech Toyo Co., Ltd.) to prepare a protective layer coating solution.
This protective layer coating liquid was applied onto the charge transport layer by dip coating, and the resulting coating film was dried at 50° C. for 5 minutes. After drying, the coating film was irradiated with an electron beam for 1.6 seconds under conditions of an acceleration voltage of 70 kV and an absorption dose of 5000 Gy in a nitrogen atmosphere. After that, heat treatment was performed for 1 hour under the condition that the temperature of the coating film was 120° C. in a nitrogen atmosphere to form a protective layer having a thickness of 5 μm.

After that, the surface of the electrophotographic photosensitive member was polished. Polishing was performed using the polishing apparatus shown in FIG. 3 under the following conditions.
Feeding speed of abrasive sheet; 400mm/min
Rotational speed of electrophotographic photoreceptor: 450 rpm
Pushing into the backup roller of the electrophotographic photosensitive member; 3.5 mm
Rotation direction of abrasive sheet and electrophotographic photosensitive member; with backup roller; outer diameter 100 mm, Asker C hardness 25
A polishing sheet 101 to be attached to the polishing apparatus was prepared by mixing abrasive grains used in GC3000 and GC2000 manufactured by Riken Corundum Co., Ltd.
GC3000 (polishing sheet surface roughness Ra 0.83 μm)
GC2000 (polishing sheet surface roughness Ra 1.45 μm)
Polishing sheet 101 (polishing sheet surface roughness Ra 1.12 μm)
The polishing time using the polishing sheet 101 was 20 seconds.
The produced electrophotographic photoreceptor was evaluated in the same manner as in Example 1.

In FIG. 3, the polishing sheet 101 is wound around a hollow shaft 106, and a motor (not shown) is arranged to apply tension to the polishing sheet 101 in the direction opposite to the direction in which the polishing sheet 101 is fed to the shaft 106. ing. The polishing sheet 101 is fed in the direction of the arrow, passes through the backup roller 103 via the guide rollers 102a and 102b, and the polishing sheet 101 after polishing is fed to the winding means 105 by the motor (not shown) via the guide rollers 102c and 102d. be wound up. Polishing is performed by constantly pressing the polishing sheet 101 against an object to be processed (an electrophotographic photosensitive member before polishing) 104 . Since the polishing sheet 101 is often insulative, it is preferable to use a grounded material or a conductive material for the portion in contact with the polishing sheet 101 . The feeding speed of the polishing sheet 101 is preferably in the range of 10-1000 mm/min. If the feeding amount is too small, the binding resin may adhere to the surface of the polishing sheet 101, resulting in deep scratches on the surface of the object 104 to be processed. The object 104 to be processed is placed at a position facing the backup roller 103 with the polishing sheet 101 interposed therebetween. From the viewpoint of improving the uniformity of the surface roughness of the object 104 to be processed, the backup roller 103 is preferably an elastic body. At this time, the object to be processed 104 and the backup roller 103 are pressed against each other at a desired set value for a predetermined time through the polishing sheet 101, and the surface of the object to be processed 104 is polished. The direction of rotation of the object 104 to be processed may be the same as or opposite to the direction in which the polishing sheet 101 is fed. Also, the direction of rotation may be changed during polishing. The surface roughness of the object 104 to be processed is determined by appropriately selecting the feeding speed of the polishing sheet 101, the pressing pressure of the backup roller 103, the abrasive grain type of the polishing sheet, the film thickness of the binder resin of the polishing sheet, the thickness of the substrate, and the like. can be adjusted by

分散処理後、シリコーンオイル（商品名：ＳＨ２８ＰＡ、東レダウコーニングシリコーン社製）０．０１部、架橋ポリメタクリル酸メチル（ＰＭＭＡ）粒子（商品名：ＴＥＣＨＰＯＬＹＭＥＲ ＳＳＸ－１０３、積水化成品工業（株）製、平均一次粒径：３μｍ）を５．６部加えて攪拌することによって、下引き層用塗布液を調製した。
この下引き層用塗布液を上記支持体上に浸漬塗布して塗膜を形成し、この塗膜を４０分間１６０℃で乾燥（加熱乾燥）させて、膜厚が３０μｍの下引き層を形成した。
それ以外は実施例１と同様にして、実施例１８の電子写真感光体を製造し、帯電横スジおよび黒点の評価、ならびに下引き層の構成物の評価を行った。 <Example 18>
In Example 1, the method of forming the coating liquid for the undercoat layer was changed as follows.
Butyral resin (trade name: BM-1, manufactured by Sekisui Chemical Co., Ltd.) 15 parts and blocked isocyanate (trade name: Duranate TPA-B80E, non-volatile content 80% by mass, manufactured by Asahi Kasei Chemicals Co., Ltd.) 15 parts, A solution was obtained by dissolving in a mixed solvent of 65 parts of methyl ethyl ketone and 65 parts of 1-butanol. To this solution were added 10 parts of the surface-treated zinc oxide particles ZnO(L), 71 parts of the surface-treated zinc oxide particles ZnO(M), and 0.4 of a compound represented by the following formula (1) (benzophenone derivative). (manufactured by Tokyo Kasei Kogyo Co., Ltd.), placed in a sand mill apparatus using glass beads with a diameter of 0.8 mm, and subjected to dispersion treatment in an atmosphere of 23±3° C. for 3 hours.

After dispersion treatment, silicone oil (trade name: SH28PA, manufactured by Dow Corning Toray Silicone Co., Ltd.) 0.01 part, crosslinked polymethyl methacrylate (PMMA) particles (trade name: TECHPOLYMER SSX-103, manufactured by Sekisui Plastics Co., Ltd. , average primary particle diameter: 3 μm) was added and stirred to prepare a coating solution for an undercoat layer.
This undercoat layer coating liquid is dip-coated on the support to form a coating film, and this coating film is dried (heat dried) at 160° C. for 40 minutes to form an undercoat layer having a thickness of 30 μm. did.
Otherwise, an electrophotographic photoreceptor of Example 18 was produced in the same manner as in Example 1, and evaluation of charging horizontal streaks and black spots and evaluation of the composition of the undercoat layer were carried out.

<Example 19>
In Example 18, 10 parts of zinc oxide particles ZnO(L) were changed to 10 parts of zinc oxide particles ZnO(N), and 71 parts of zinc oxide particles ZnO(M) were changed to 71 parts of zinc oxide particles ZnO(O). . Otherwise, in the same manner as in Example 18, an undercoat layer coating solution of Example 19 was prepared.
An electrophotographic photoreceptor of Example 19 was produced in the same manner as in Example 18, except that the undercoat layer coating liquid of Example 19 was used to form an undercoat layer on the support. A black spot evaluation was made, as well as an evaluation of the composition of the undercoat layer.

<Example 20>
In Example 18, 10 parts of zinc oxide particles ZnO(L) were changed to 6 parts of zinc oxide particles ZnO(P), and 71 parts of zinc oxide particles ZnO(M) were changed to 75 parts of zinc oxide particles ZnO(Q). . Except for this, the same procedure as in Example 18 was repeated to prepare a coating liquid for an undercoat layer of Example 20.
An electrophotographic photoreceptor of Example 20 was produced in the same manner as in Example 18 except that the undercoat layer coating liquid of Example 20 was used to form an undercoat layer on the support. A black spot evaluation was made, as well as an evaluation of the composition of the undercoat layer.

<Example 21>
In Example 18, 10 parts of zinc oxide particles ZnO(L) were changed to 6 parts of zinc oxide particles ZnO(R), and 71 parts of zinc oxide particles ZnO(M) were changed to 75 parts of zinc oxide particles ZnO(S). Except for this, in the same manner as in Example 18, an undercoat layer coating solution of Example 21 was prepared.
An electrophotographic photoreceptor of Example 21 was produced in the same manner as in Example 18 except that the undercoat layer coating liquid of Example 21 was used to form an undercoat layer on the support. A black spot evaluation was made, as well as an evaluation of the composition of the undercoat layer.

<Comparative Example 1>
In Example 1, the amount of zinc oxide particles ZnO (A) used was changed from 12 parts to 1 part, and the amount of zinc oxide particles ZnO (B) used was changed from 69 parts to 80 parts. Except for this, the same procedure as in Example 1 was repeated to prepare a coating solution for an undercoat layer of Comparative Example 1.
An electrophotographic photoreceptor of Comparative Example 1 was produced in the same manner as in Example 1 except that the undercoat layer coating liquid of Comparative Example 1 was used to form an undercoat layer on the support. A black spot evaluation was made, as well as an evaluation of the composition of the undercoat layer.

<Comparative Example 2>
In Example 1, the amount of zinc oxide particles ZnO (A) used was changed from 12 parts to 28 parts, and the amount of zinc oxide particles ZnO (B) used was changed from 69 parts to 53 parts. Except for this, the same procedure as in Example 1 was repeated to prepare an undercoat layer coating liquid of Comparative Example 2.
An electrophotographic photoreceptor of Comparative Example 2 was produced in the same manner as in Example 1 except that the undercoat layer coating liquid of Comparative Example 2 was used to form an undercoat layer on the support. A black spot evaluation was made, as well as an evaluation of the composition of the undercoat layer.

<Comparative Example 3>
In Example 6, the amount of zinc oxide particles ZnO (A) used was changed from 10 parts to 7 parts, and the amount of zinc oxide particles ZnO (B) used was changed from 63 parts to 43 parts. Furthermore, the amount of ZnO (C) used was changed from 4 parts to 6 parts, and the amount of ZnO (D) used was changed from 4 parts to 25 parts to prepare a coating solution for an undercoat layer. Other than that, in the same manner as in Example 6, a coating solution for an undercoat layer of Comparative Example 3 was prepared.
An electrophotographic photoreceptor of Comparative Example 3 was produced in the same manner as in Example 6 except that the undercoat layer coating solution of Comparative Example 3 was used to form an undercoat layer on the support. A black spot evaluation was made, as well as an evaluation of the composition of the undercoat layer.

<Comparative Example 4>
In Example 1, the amount of butyral resin (trade name: BM-1, manufactured by Sekisui Chemical Co., Ltd.) was changed from 15 parts to 22 parts. Also, the amount of blocked isocyanate (trade name: Sumidur 3175, manufactured by Sumitomo Bayern Urethane Co., Ltd., 75% non-volatile content) was changed from 20 parts to 29 parts. Except for this, the same procedure as in Example 1 was repeated to prepare a coating solution for an undercoat layer of Comparative Example 4.
An electrophotographic photoreceptor of Comparative Example 4 was produced in the same manner as in Example 1 except that the undercoat layer coating liquid of Comparative Example 4 was used to form an undercoat layer on the support. A black spot evaluation was made, as well as an evaluation of the composition of the undercoat layer.

<Comparative Example 5>
In Example 1, the amount of butyral resin (trade name: BM-1, manufactured by Sekisui Chemical Co., Ltd.) was changed from 15 parts to 10 parts. In addition, the amount of blocked isocyanate (trade name: Sumidur 3175, manufactured by Sumitomo Bayern Urethane Co., Ltd., 75% non-volatile content) was changed from 20 parts to 14 parts. A coating solution for an undercoat layer of Comparative Example 5 was prepared in the same manner as in Example 1 except for the above.
An electrophotographic photoreceptor of Comparative Example 5 was produced in the same manner as in Example 1 except that the undercoat layer coating solution of Comparative Example 5 was used to form an undercoat layer on the support. A black spot evaluation was made, as well as an evaluation of the composition of the undercoat layer.

<Comparative Example 6>
In Example 1, instead of using ZnO (A) and ZnO (B) as zinc oxide particles, 12 parts of ZnO (G) and 69 parts of ZnO (H) were used to prepare the undercoat layer coating liquid. prepared. A coating solution for an undercoat layer of Comparative Example 6 was prepared in the same manner as in Example 1 except for the above.
An electrophotographic photoreceptor of Comparative Example 6 was produced in the same manner as in Example 1 except that the undercoat layer coating liquid of Comparative Example 6 was used to form an undercoat layer on the support. A black spot evaluation was made, as well as an evaluation of the composition of the undercoat layer.

<Comparative Example 7>
In Example 1, ZnO (B) was changed from 69 parts to 72 parts without using ZnO (A) as the zinc oxide particles. Further, 9 parts of ZnO(I) was added to prepare an undercoat layer coating solution. Other than that, in the same manner as in Example 1, a coating solution for an undercoat layer of Comparative Example 7 was prepared.
An electrophotographic photoreceptor of Comparative Example 7 was produced in the same manner as in Example 1 except that the undercoat layer coating liquid of Comparative Example 7 was used to form an undercoat layer on the support. A black spot evaluation was made, as well as an evaluation of the composition of the undercoat layer.

(Evaluation results)
Table 1 shows the results of the evaluation of the composition of the undercoat layer and the evaluation of charging horizontal streaks and black spots for Examples 1 to 21 and Comparative Examples 1 to 7.

1-1 support 1-2 undercoat layer 1-3 photosensitive layer

Reference Signs List 1 Electrophotographic photosensitive member 2 Shaft 3 Charging means 4 Exposure light 5 Developing means 6 Transfer means 7 Transfer material 8 Fixing means 9 Cleaning means 10 Pre-exposure light 11 Process cartridge 12 Guiding means

101 polishing sheet 102a guide roller 102b guide roller 103 backup roller 104 object to be processed (electrophotographic photosensitive member before polishing)
105 winding means 106 hollow shaft

5-1 Object to be processed (electrophotographic photoreceptor before processing)
5-2 mold 5-3 pressure member 5-4 support member

Claims (10)

In an electrophotographic photoreceptor having a support, an undercoat layer, and a photosensitive layer in this order,
The undercoat layer
binding resin,
zinc oxide particles (P1) having a particle size in the range of 20 nm or more and 40 nm or less ;
Zinc oxide particles (P2) having a particle size in the range of 45 nm or more and 65 nm or less , and
benzophenone derivatives,
contains
The benzophenone derivative is a compound represented by the following formula (1),

The total content of zinc oxide particles in the undercoat layer is 200% by mass or more and 350% by mass or less with respect to the binder resin in the undercoat layer,
The total content of the zinc oxide particles (P2) and the zinc oxide particles (P1) in the undercoat layer is 50% by number or more and 100% of the total content of zinc oxide particles in the undercoat layer. % or less,
The content of the zinc oxide particles (P1) in the undercoat layer is 5 pieces with respect to the total content of the zinc oxide particles (P2) and the zinc oxide particles (P1) in the undercoat layer % or more and 60 number % or less,
The difference between the mode of particle size of the zinc oxide particles (P2) and the mode of particle size of the zinc oxide particles (P1) in the undercoat layer is 10 nm or more .
An electrophotographic photoreceptor characterized by: The content of the zinc oxide particles (P1) in the undercoat layer is 10 pieces with respect to the total content of the zinc oxide particles (P2) and the zinc oxide particles (P1) in the undercoat layer. % or more and 50% or less by number. The total content of the zinc oxide particles (P2) and the zinc oxide particles (P1) in the undercoat layer is 75% by number or more and 100% of the total content of zinc oxide particles in the undercoat layer. 3. The electrophotographic photoreceptor according to claim 1 or 2, wherein the number is % or less. 4. The zinc oxide particles (P2) and the zinc oxide particles (P1) in the undercoat layer are both treated with a silane coupling agent having an amino group. The electrophotographic photoreceptor described in . 5. The electrophotographic photoreceptor according to claim 4, wherein the silane coupling agent having an amino group is N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane . The electrophotographic photosensitive member according to any one of claims 1 to 5 and at least one means selected from the group consisting of charging means, developing means, transfer means and cleaning means are integrally supported, and electrophotographic A process cartridge, characterized in that it is detachable from an apparatus main body. 7. A process cartridge according to claim 6 , wherein said charging means has a charging member, and said charging member and said electrophotographic photosensitive member are in contact with each other. An electrophotographic apparatus comprising the electrophotographic photoreceptor according to any one of claims 1 to 5, charging means, exposure means , developing means and transfer means. 9. The electrophotographic apparatus according to claim 8 , wherein said charging means has a charging member, and said charging member and said electrophotographic photosensitive member are in contact with each other. 10. The electrophotographic apparatus according to claim 9, wherein said electrophotographic apparatus has a power supply for applying only a DC voltage to said charging member.

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