JP2016095339A - Electrophotographic photoreceptor, electrophotographic image forming apparatus, and process cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor that can maintain high wear resistance, has good difference in image density (image memory) due to a period of the photoreceptor, and has strong resistance against fogging.SOLUTION: An electrophotographic photoreceptor includes a conductive support, and a photosensitive layer and a surface layer sequentially provided on the conductive support. The surface layer includes p-type semiconductor particles, and first particles that are at least one of zirconium dioxide particles, silicon dioxide particles, and aluminum dioxide particles. The content of the first particles on the surface layer is preferably 0.05 mass% or more and 5 mass% or less of the content of the p-type semiconductor particles.SELECTED DRAWING: None

Description

  The present invention relates to an electrophotographic photosensitive member having a surface layer on a photosensitive layer, and relates to an electrophotographic image forming apparatus and a process cartridge provided with the electrophotographic photosensitive member.

  In Patent Document 1 (Japanese Patent Laid-Open No. 2013-130603), by adding p-type semiconductor particles to the surface layer of the electrophotographic photosensitive member, the wear resistance of the electrophotographic photosensitive member is improved, and the period of the photosensitive member is also increased. It is described that the image density difference (image memory) is good.

JP 2013-130603 A

  However, it has now been found that fog is likely to occur when p-type semiconductor particles are added to the surface layer of an electrophotographic photoreceptor. An object of the present invention is to provide an electrophotographic photosensitive member that can maintain high wear resistance, has a good image density difference (image memory) depending on the photosensitive member cycle, and has a high anti-fogging property.

The electrophotographic photosensitive member of the present invention includes a conductive support and a photosensitive layer and a surface layer that are sequentially provided on the conductive support. The surface layer includes p-type semiconductor particles and first particles that are at least one of zirconium dioxide (ZrO ₂ ) particles, silicon dioxide (SiO ₂ ) particles, and aluminum oxide (Al ₂ O ₃ ) particles.

  In the surface layer, the content of the first particles is preferably 0.05% by mass or more and 5% by mass or less of the content of the p-type semiconductor particles. The “content of first particles” means the total of the content of zirconium dioxide particles, the content of silicon dioxide particles, and the content of aluminum oxide particles. For example, when the surface layer contains zirconium dioxide particles but does not contain silicon dioxide particles and aluminum oxide particles, the content of silicon dioxide particles and the content of aluminum oxide particles are both 0 parts by mass. The “content” is the content of zirconium dioxide particles.

  The first particles are preferably zirconium dioxide particles. Moreover, it is preferable that a surface layer further contains the component obtained by hardening of a curable compound.

The p-type semiconductor particles are preferably made of a metal oxide, and are made of at least one of a metal oxide represented by the following general formula (1) and a metal oxide represented by the following general formula (2). It is more preferable. M1 in the following general formula (1) represents a group 13 element in the periodic table. M2 in the following general formula (2) represents a Group 2 element in the periodic table.
Cu (M1) O ₂ General formula (1)
(M2) Cu ₂ O ₂ General formula (2).

  The electrophotographic image forming apparatus of the present invention includes an electrophotographic photosensitive member of the present invention, a charging unit that charges the surface of the electrophotographic photosensitive member, an exposure unit that forms an electrostatic latent image on the surface of the electrophotographic photosensitive member, And a developing unit that develops the electrostatic latent image with toner to form a toner image.

  The process cartridge of the present invention is detachably mounted on the electrophotographic image forming apparatus, and the electrophotographic photosensitive member of the present invention, a charging unit for charging the surface of the electrophotographic photosensitive member, and electrostatic on the surface of the electrophotographic photosensitive member. An exposure unit that forms a latent image and a developing unit that develops the electrostatic latent image with toner to form a toner image.

  The electrophotographic photosensitive member of the present invention can maintain high wear resistance, has a good image density difference (image memory) depending on the photosensitive member cycle, and has a high resistance to fog.

1 is a schematic cross-sectional view of an electrophotographic photosensitive member according to an embodiment of the present invention. 1 is a cross-sectional view illustrating a configuration of an electrophotographic image forming apparatus according to an embodiment of the present invention.

  The present invention will be described below with reference to the drawings. In the drawings of the present invention, the same reference numerals represent the same or corresponding parts. In addition, dimensional relationships such as length, width, thickness, and depth are changed as appropriate for clarity and simplification of the drawings, and do not represent actual dimensional relationships.

[Configuration of electrophotographic photoreceptor]
FIG. 1 is a schematic cross-sectional view of an electrophotographic photosensitive member according to an embodiment of the present invention. The electrophotographic photoreceptor 100 includes a conductive support 101, and a photosensitive layer 103 and a surface layer 106 that are sequentially provided on the conductive support 101. The electrophotographic photoreceptor 100 preferably further includes an intermediate layer 102 between the conductive support 101 and the photosensitive layer 103. The photosensitive layer 103 preferably includes a charge generation layer 104 provided on the intermediate layer 102 and a charge transport layer 105 provided on the charge generation layer 104. In the following, after the surface layer 106 is shown, the configuration of the electrophotographic photoreceptor 100 other than the surface layer 106 is shown.

<Configuration of surface layer>
The surface layer 106 is made of a resin and includes p-type semiconductor particles and first particles that are at least one of zirconium dioxide particles, silicon dioxide particles, and aluminum oxide particles. Since the surface layer 106 includes p-type semiconductor particles, the abrasion resistance of the electrophotographic photoreceptor 100 is improved, and the image density difference (image memory) due to the photoreceptor period is improved.

  Since the surface layer 106 includes the first particles, the fog resistance is increased. The reason why such an effect is obtained cannot be determined, but it is considered that the resistance of the first particles is high.

  The thickness of the surface layer 106 is preferably 0.2 μm or more and 10 μm or less, and more preferably 0.5 μm or more and 6 μm or less. Hereinafter, after describing the first particles, the resin constituting the surface layer 106 and the p-type semiconductor will be described in order.

(First particle)
The first particles preferably have a number average primary particle size of 1 nm to 100 nm, and more preferably a number average primary particle size of 2 nm to 90 nm.

  The number average primary particle size of the first particles can be calculated according to the following method. First, an enlarged photograph (magnification is 100,000 times) of the first particles is taken using a scanning electron microscope (for example, a product number “JSM-7500F” manufactured by JEOL Ltd.). 300 magnified photographs of the first particles are randomly selected from the photographed magnified photographs, and the selected magnified photographs are taken into the scanner. Using the photographic image (excluding aggregated particles) captured by the scanner and an automatic image processing analyzer (for example, product number “LUZEX AP” manufactured by Nireco Corporation, software: Ver. 1.32), the first particles The number average primary particle size is calculated.

  The first particles are preferably zirconium dioxide particles. This further improves the image memory.

  The content of the first particles is preferably 0.05% by mass or more and 5% by mass or less of the content of the p-type semiconductor particles. As a result, the fog resistance is further enhanced. The content of the first particles is more preferably 0.07% by mass to 4.5% by mass of the content of the p-type semiconductor particles, and 0.1% by mass to 4% of the content of the p-type semiconductor particles. More preferably, it is at most mass%. Whether or not the surface layer 106 contains the first particles, the material of the first particles, the content of the first particles, and the like can be confirmed by fluorescent X-ray analysis. The method for producing such first particles is not particularly limited, and a commercially available product may be used.

(Resin constituting the surface layer)
As the resin constituting the surface layer 106, a conventionally known resin can be used as the resin constituting the surface layer of the electrophotographic photosensitive member. The resin constituting the surface layer 106 preferably includes a component obtained by curing (for example, thermosetting or photocuring) of a curable compound (for example, a curable resin), but may be a resin that does not include the above components. It may be a mixture of a resin containing the above components and a resin not containing the above components. As resin which does not contain the said component, a polyester resin, a polycarbonate resin, a polyurethane resin, or a silicone resin etc. are mentioned, for example.

  The “curable compound” means a monomer or oligomer that is polymerized by the above curing, and is preferably a radical polymerizable compound. The “radical polymerizable compound” means a compound that undergoes a radical polymerization reaction due to heat irradiation, ultraviolet irradiation, electromagnetic wave irradiation, electron beam irradiation, or the like, resulting in polymerization. Therefore, when the curable compound is a radical polymerizable compound, the cured resin contains the curable compound as a repeating unit.

  The radical polymerizable compound preferably contains at least one of an acryloyl group and a methacryloyl group as a radical polymerizable reactive group (functional group contributing to the radical polymerization reaction). As a result, acryloyl groups, methacryloyl groups, or acryloyl groups and methacryloyl groups are radically polymerized and polymerized. As such a radically polymerizable compound, for example, compounds represented by the following chemical formulas (1) to (15) can be used. In the following chemical formulas (1) to (15), R represents an acryloyl group represented by the following chemical formula (16), and R ′ represents a methacryloyl group represented by the following chemical formula (17).

(P-type semiconductor particles)
The “p-type semiconductor particle” means a semiconductor particle in which holes are used as carriers for transporting charges, that is, semiconductor particles in which holes are majority carriers.

(Material of p-type semiconductor particles)
The p-type semiconductor particles used in the present embodiment are preferably made of a metal oxide, and among the metal oxide represented by the following general formula (1) and the metal oxide represented by the following general formula (2) More preferably, it consists of at least one of the following. The material of the p-type semiconductor particles can be confirmed using a fluorescent X-ray analyzer.

Cu (M1) O ₂ General formula (1)
In the general formula (1), M1 represents a group 13 element in the periodic table, and specifically, boron (B), aluminum (Al), gallium (Ga), indium (In), or thallium (Tl). Represents. Among them, M1 preferably represents at least one of aluminum, gallium, and indium. The metal oxide represented by the general formula (1) is preferably at least one of CuAlO ₂ , CuGaO ₂ and CuInO ₂ . When the surface layer 106 contains these p-type semiconductor particles, the abrasion resistance of the electrophotographic photoreceptor 100 can be maintained high, and the image density difference (image memory) due to the photoreceptor period is further improved.

(M2) Cu ₂ O ₂ ... General formula (2)
In the general formula (2), M2 represents a Group 2 element in the periodic table, and specifically, beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), or barium (Ba). Represents. Among these, M2 preferably represents at least one of magnesium, calcium, strontium, and barium. The metal oxide represented by the general formula (2) is preferably at least one of MgCu ₂ O ₂ , CaCu ₂ O ₂ , SrCu ₂ O ₂ and BaCu ₂ O ₂ . When the surface layer 106 contains these p-type semiconductor particles, the abrasion resistance of the electrophotographic photoreceptor 100 can be maintained high, and the image density difference (image memory) due to the photoreceptor period is further improved.

  The p-type semiconductor particles preferably have a number average primary particle size of 1 nm to 300 nm, and more preferably 3 nm to 100 nm. The number average primary particle size of the p-type semiconductor particles can be calculated according to the same method as the method for calculating the number average primary particle size of the first particles.

  The p-type semiconductor particles are preferably contained in an amount of 10% by mass to 300% by mass with respect to the resin constituting the surface layer 106. As a result, the wear resistance can be maintained at a higher level, and the image density difference (image memory) due to the photoconductor cycle is further improved. The p-type semiconductor particles are more preferably contained in an amount of 20% by mass or more and 200% by mass or less with respect to the resin constituting the surface layer 106.

(Preparation of p-type semiconductor particles)
Such p-type semiconductor particles are preferably produced by, for example, a plasma method. Examples of the plasma method include a direct current plasma arc method, a high frequency plasma method, and a plasma jet method.

  The direct current plasma arc method uses an anode electrode made of a metal alloy (this anode electrode is consumed). A plasma flame is generated from the cathode electrode. The metal alloy is evaporated by heating the anode electrode, and p-type semiconductor particles are obtained by oxidizing and cooling the vapor of the metal alloy.

  The high frequency plasma method uses thermal plasma generated when a gas is heated by high frequency induction discharge under atmospheric pressure. Among them, the plasma evaporation method was obtained by injecting solid particles into the center of an inert gas plasma (inert gas converted into plasma) and evaporating the solid particles while passing through the plasma. P-type semiconductor particles can be obtained by rapidly cooling and condensing high-temperature steam.

  When arc discharge is performed in an inert gas argon atmosphere, argon plasma is obtained. Further, when arc discharge is performed in an atmosphere of hydrogen, nitrogen, or oxygen that is a diatomic molecular gas, hydrogen plasma, nitrogen plasma, or oxygen plasma is obtained, respectively. In particular, hydrogen plasma, nitrogen plasma, or oxygen plasma generated by thermal dissociation of diatomic molecular gas is extremely reactive compared to molecular gas plasma, so it is different from inert gas plasma. Also called arc plasma. Among these, the production of p-type semiconductor particles using oxygen plasma is effective as a method for producing p-type semiconductor particles.

(Surface-treated p-type semiconductor particles)
In the present embodiment, the p-type semiconductor particles are preferably those that have been surface-treated with a surface treatment agent. The surface treatment agent is preferably a surface treatment agent that reacts with a hydroxy group or the like present on the surface of the p-type semiconductor particles, and is preferably a silane coupling agent or a titanium coupling agent, for example. Therefore, the composition of the metal oxide constituting the p-type semiconductor particles and the shape of the p-type semiconductor particles (for example, the number average primary particle diameter of the p-type semiconductor particles) are not changed before and after the surface treatment. In the following, p-type semiconductor particles that have not been surface-treated are simply referred to as “p-type semiconductor particles”, and p-type semiconductor particles that have undergone surface treatment are referred to as “surface-treated p-type semiconductor particles”.

  The surface treatment agent more preferably has a reactive organic group. Thereby, the hardness of the surface layer 106 can be further increased.

  The surface treatment agent having a reactive organic group is preferably a surface treatment agent having a radical polymerizable reactive group. The radical polymerizable reactive group can also react with the curable compound. Therefore, if the surface treatment of the p-type semiconductor particles is performed using a surface treatment agent having a radical polymerizable reactive group, a strong surface layer 106 can be formed. For example, when the resin constituting the surface layer 106 includes a component obtained by curing of the curable compound (for example, a curable resin), the surface-treated p-type semiconductor particles and the resin constituting the surface layer 106 are subjected to a curing reaction. Will be combined.

The surface treatment agent having a radical polymerizable reactive group is preferably a silane coupling agent having a radical polymerizable reactive group such as a vinyl group, an acryloyl group or a methacryloyl group. For example, as the surface treating agent having a radical polymerizable reactive group, known compounds described in the following S-1 to S-36 can be used. In addition to the known compounds described in S-1 to S-36 below, silane compounds having a radical polymerizable reactive group may be used. As the surface treatment agent, these compounds can be used alone or in admixture of two or more.
_{S-1: CH 2 = CHSi} (CH 3) (OCH 3) 2
_{S-2: CH 2 = CHSi} (OCH 3) 3
S-3: CH ₂ = CHSiCl _{3
S-4: CH 2 = CHCOO} (CH 2) 2 Si (CH 3) (OCH 3) 2
_{S-5: CH 2 = CHCOO} (CH 2) 2 Si (OCH 3) 3
_{S-6: CH 2 = CHCOO} (CH 2) 2 Si (OC 2 H 5) (OCH 3) 2
_{S-7: CH 2 = CHCOO} (CH 2) 3 Si (OCH 3) 3
_{S-8: CH 2 = CHCOO} (CH 2) 2 Si (CH 3) Cl 2
_{S-9: CH 2 = CHCOO} (CH 2) 2 SiCl 3
_{S-10: CH 2 = CHCOO} (CH 2) 3 Si (CH 3) Cl 2
S-11: CH ₂ = CHCOO (CH ₂ ) ₃ SiCl _{3
S-12: CH 2 = C} (CH 3) COO (CH 2) 2 Si (CH 3) (OCH 3) 2
_{S-13: CH 2 = C} (CH 3) COO (CH 2) 2 Si (OCH 3) 3
_{S-14: CH 2 = C} (CH 3) COO (CH 2) 3 Si (CH 3) (OCH 3) 2
_{S-15: CH 2 = C} (CH 3) COO (CH 2) 3 Si (OCH 3) 3
_{S-16: CH 2 = C} (CH 3) COO (CH 2) 2 Si (CH 3) Cl 2
_{S-17: CH 2 = C} (CH 3) COO (CH 2) 2 SiCl 3
_{S-18: CH 2 = C} (CH 3) COO (CH 2) 3 Si (CH 3) Cl 2
_{S-19: CH 2 = C} (CH 3) COO (CH 2) 3 SiCl 3
_{S-20: CH 2 = CHSi} (C 2 H 5) (OCH 3) 2
_{S-21: CH 2 = C} (CH 3) Si (OCH 3) 3
_{S-22: CH 2 = C} (CH 3) Si (OC 2 H 5) 3
_{S-23: CH 2 = CHSi} (OCH 3) 3
_{S-24: CH 2 = C} (CH 3) Si (CH 3) (OCH 3) 2
_{S-25: CH 2 = CHSi} (CH 3) Cl 2
_{S-26: CH 2 = CHCOOSi} (OCH 3) 3
_{S-27: CH 2 = CHCOOSi} (OC 2 H 5) 3
_{S-28: CH 2 = C} (CH 3) COOSi (OCH 3) 3
_{S-29: CH 2 = C} (CH 3) COOSi (OC 2 H 5) 3
_{S-30: CH 2 = C} (CH 3) COO (CH 2) 3 Si (OC 2 H 5) 3
_{S-31: CH 2 = CHCOO} (CH 2) 2 Si (CH 3) 2 (OCH 3)
_{S-32: CH 2 = CHCOO} (CH 2) 2 Si (CH 3) (OCOCH 3) 2
_{S-33: CH 2 = CHCOO} (CH 2) 2 Si (CH 3) (ONHCH 3) 2
_{S-34: CH 2 = CHCOO} (CH 2) 2 Si (CH 3) (OC 6 H 5) 2
_{S-35: CH 2 = CHCOO} (CH 2) 2 Si (C 10 H 21) (OCH 3) 2
_{S-36: CH 2 = CHCOO} (CH 2) 2 Si (CH 2 C 6 H 5) (OCH 3) 2.

  The surface-treated p-type semiconductor particles are preferably contained in an amount of 5% by volume to 75% by volume with respect to the resin constituting the surface layer 106.

(Production of surface-treated p-type semiconductor particles)
Surface-treated p-type semiconductor particles can be prepared by putting p-type semiconductor particles, a surface treatment agent and a solvent in a wet media dispersion type apparatus and pulverizing them. For example, a slurry (suspension containing solid particles) containing p-type semiconductor particles and a surface treatment agent is pulverized. Thereby, the surface treatment for the p-type semiconductor particles proceeds simultaneously with the miniaturization of the p-type semiconductor particles. Thereafter, when the solvent is removed to form powder, p-type semiconductor particles in which the surface treatment with the surface treatment agent is uniformly performed can be obtained.

  At this time, it is preferable to supply 0.1-100 mass parts surface treating agent and 50-5000 mass parts solvent with respect to 100 mass parts of p-type semiconductor particles to a wet media dispersion type | mold apparatus. Alternatively, the surface-treated p-type semiconductor particles may be produced by dry surface treatment.

  The “wet media dispersion type device” in this embodiment is a state in which beads are filled in a container as a medium (grinding medium) and a stirring disk attached perpendicularly to the rotation axis is rotated at high speed in the container. Means an apparatus for pulverizing an aggregate of p-type semiconductor particles and dispersing the pulverized p-type semiconductor particles. The configuration of the wet media dispersion type apparatus is not particularly limited as long as the surface treatment can be performed on the p-type semiconductor particles in a state in which the p-type semiconductor particles are sufficiently dispersed, and is a vertical type or a horizontal type. Alternatively, it may be a continuous type or a batch type. As the wet media dispersion type apparatus, for example, a sand mill, an ultra visco mill, a pearl mill, a glen mill, a dyno mill, an agitator mill, a dynamic mill, or the like can be used. In these devices, impact crushing, frictional force, shear stress, shear stress, etc. are generated using media such as balls or beads. As a result, p-type semiconductor particles are pulverized and pulverized p-type semiconductor particles. Is distributed.

  As beads used in the wet media dispersion type apparatus, balls made of glass, alumina, zircon, zirconia, steel, flint stone, etc. can be used, but in particular, zircon balls or zirconia balls can be used. preferable. Moreover, as a bead, the ball | bowl with a diameter of about 1-2 mm is normally used, However, In this embodiment, it is preferable to use a ball | bowl with a diameter of about 0.1-1.0 mm.

  Various materials such as stainless steel, nylon, and ceramic can be used as the material for the stirring disk or the inner wall of the container used in the wet media dispersion type apparatus. In this embodiment, a ceramic material such as zirconia or silicon carbide is used. Is preferred.

<Formation of surface layer>
When the resin constituting the surface layer 106 includes a component obtained by curing the curable compound (for example, a curable resin), the surface layer 106 can be formed according to the following method.

(Preparation of surface layer forming liquid)
First, a curable compound (preferably a radical polymerizable compound), p-type semiconductor particles (preferably surface-treated p-type semiconductor particles), and first particles are added to a solvent to prepare a surface layer forming liquid. . The surface layer forming liquid may further contain a known resin, a polymerization initiator, lubricant particles, an antioxidant, or the like, if necessary.

(solvent)
Examples of the solvent used for forming the surface layer 106 include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-2-propanol, benzyl alcohol, methyl isopropyl ketone, Methyl isobutyl ketone, methyl ethyl ketone, cyclohexane, toluene, xylene, methylene chloride, ethyl acetate, butyl acetate, 2-methoxyethanol, 2-ethoxyethanol, tetrahydrofuran, 1-dioxane, 1,3-dioxolane, pyridine, or diethylamine For example, but not limited to.

(Polymerization initiator)
In the curing treatment described later, the curing reaction may be performed by a cleavage reaction with an electron beam, or the curing reaction may be performed by irradiation with heat or light in the presence of a radical polymerization initiator. When a curing reaction is performed using a radical polymerization initiator, either a thermal polymerization initiator or a photopolymerization initiator can be used as a polymerization initiator, and both a thermal polymerization initiator and a photopolymerization initiator are used. You may do it.

  Examples of the thermal polymerization initiator include 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethylazobisvaleronyl), or 2,2′-azobis (2 Azo compounds such as -methylbutyronitrile), benzoyl peroxide (BPO (benzoyl peroxide)), di-tert-butyl hydroperoxide, tert-butyl hydroperoxide, chlorobenzoyl peroxide, dichlorobenzoyl peroxide, Examples thereof include peroxides such as bromomethylbenzoyl oxide or lauroyl peroxide.

  Examples of the photopolymerization initiator include diethoxyacetophenone, 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, 4- (2-hydroxyethoxy) phenyl- (2-hydroxy-2-propyl) ketone, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butanone-1 (product number “IRGACURE 369” manufactured by BASF Japan Ltd.), 2-hydroxy- 2-methyl-1-phenylpropan-1-one, 2-methyl-2-morpholino (4-methylthiophenyl) propan-1-one or 1-phenyl-1,2-propanedione-2- (o-ethoxycarbonyl) ) Acetophenone-based or ketal-based photopolymerization initiators such as oximes.

  Further, as the photopolymerization initiator, for example, a benzoin ether photopolymerization initiator such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isobutyl ether, or benzoin isopropyl ether may be used.

  Examples of the photopolymerization initiator include benzophenone, 4-hydroxybenzophenone, methyl o-benzoylbenzoate, 2-benzoylnaphthalene, 4-benzoylbiphenyl, 4-benzoylphenyl ether, acrylated benzophenone, or 1,4. -A benzophenone photopolymerization initiator such as benzoylbenzene may be used.

  Examples of the photopolymerization initiator include thioxanthone photopolymerization initiation such as 2-isopropylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, or 2,4-dichlorothioxanthone. An agent may be used.

  Other photopolymerization initiators include ethyl anthraquinone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylethoxyphosphine oxide, bis (2,4,6-trimethylbenzoyl) phenylphosphine Oxide (product number “IRGACURE 819” manufactured by BASF Japan Ltd.), bis (2,4-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, methylphenylglyoxyester, 9,10-phenanthrene, acridine series Examples thereof include compounds, triazine compounds, and imidazole compounds.

  Those having a photopolymerization promoting effect can be used alone or in combination with the photopolymerization initiator. Examples of the material having a photopolymerization promoting effect include, for example, triethanolamine, methyldiethanolamine, ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, (2-dimethylamino) ethyl benzoate, or 4,4 And '-dimethylaminobenzophenone.

  As the photopolymerization initiator, an alkylphenone compound or a phosphine oxide compound is more preferably used, and an initiator having an α-hydroxyacetophenone structure or an acylphosphine oxide structure is further used. preferable.

  As a polymerization initiator, the above-mentioned polymerization initiators can be used alone or in admixture of two or more. The polymerization initiator is preferably added in an amount of 0.1 to 40 parts by mass, and more preferably 0.5 to 20 parts by mass with respect to 100 parts by mass of the curable compound.

(Lubricant particles)
As the lubricant particles, for example, fluorine atom-containing resin particles can be used. Examples of the fluorine atom-containing resin particles include a tetrafluoroethylene resin, a trifluorinated ethylene chloride resin, a hexafluoroethylene chloride propylene resin, a vinyl fluoride resin, a vinylidene fluoride resin, an ethylene difluoride dichloride resin, or , And copolymers thereof. As the lubricant particles, the above-mentioned fluorine atom-containing resin particles can be used alone or in combination of two or more, and it is more preferable to use a tetrafluoroethylene resin or a vinylidene fluoride resin.

(Formation of coating film)
The prepared surface layer forming liquid is applied to the upper surface of the photosensitive layer 103 by a known method, and then naturally dried or thermally dried.

  Examples of the method for applying the surface layer forming liquid include a dip coating method, a spray coating method, a spinner coating method, a bead coating method, a blade coating method, a beam coating method, and a circular amount regulating type application method. The same applies to the method for applying the intermediate layer forming liquid (described later), the method for applying the charge generating layer forming liquid (described later), and the method for applying the charge transport layer forming liquid (described later). The circular amount regulation type coating method is described in, for example, Japanese Patent Application Laid-Open No. 58-189061 or Japanese Patent Application Laid-Open No. 2005-275373.

  In this embodiment, it is preferable that the timing at which the coating film is dried is appropriately selected in combination with the irradiation condition of an actinic ray (described later). For example, the coating film may be dried before and after irradiation with actinic radiation, or the coating film may be dried during irradiation with actinic radiation.

  The drying conditions of the coating film are preferably selected as appropriate depending on the type of solvent contained in the coating film, the thickness of the coating film, and the like. The drying temperature of the coating film is preferably from room temperature to 180 ° C, and more preferably from 80 ° C to 140 ° C. Moreover, it is preferable that it is 1 minute or more and 200 minutes or less, and, as for the drying time of a coating film, it is more preferable that they are 5 minutes or more and 100 minutes or less. By drying the coating film under such conditions, the amount of solvent contained in the formed surface layer 106 can be controlled to 20 ppm or more and 75 ppm or less.

(Curing the coating)
Curing is performed on the coating film formed by applying the surface layer forming liquid. Thereby, the surface layer 106 is formed on the upper surface of the photosensitive layer 103.

  In the curing treatment, radicals are generated by irradiation with active rays on the coating to polymerize, and crosslinking is formed between molecules or within a molecule by a crosslinking reaction to cure, thereby forming a curable resin. It is preferable. Examples of the actinic rays include electromagnetic waves such as ultraviolet rays and visible light, or electron beams, and it is more preferable to use ultraviolet rays from the viewpoint of ease of use.

As the ultraviolet light source, any light source that generates ultraviolet light can be used without limitation. For example, a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultrahigh-pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp, a flash (pulse) xenon, or an ultraviolet LED (light emitting diode) can be used. The irradiation conditions of ultraviolet rays varies depending on the type of light source, but the dose of ultraviolet rays, it is more preferably preferably, 5 mJ / cm ² or more 15 mJ / cm ² or less at 1 mJ / cm ² or more 20 mJ / cm ² or less . The output voltage of the ultraviolet light source is preferably 0.1 kW to 5 kW, and more preferably 0.5 kW to 3 kW.

  The electron beam source can be used without any particular limitation. As an electron beam accelerator for electron beam irradiation, it is preferable to use a curtain beam type which is relatively inexpensive and can provide a large output. The acceleration voltage during electron beam irradiation is preferably 100 kV or more and 300 kV or less. The absorbed dose is preferably 0.005 Gy or more and 100 kGy or less (0.5 Mrad or more and 10 Mrad or less).

  The actinic ray irradiation time is preferably equal to or longer than the time required for obtaining the necessary amount of actinic radiation. Specifically, the actinic ray irradiation time is preferably from 0.1 second to 10 minutes, and more preferably from 1 second to 5 minutes from the viewpoint of curing efficiency or work efficiency.

<Conductive support>
The conductive support 101 is not particularly limited as long as it has conductivity. For example, a metal such as aluminum, copper, chromium, nickel, zinc, or stainless steel formed into a drum shape or a sheet shape, an aluminum foil, or copper Metal foil such as foil laminated on plastic film, aluminum, indium oxide or tin oxide deposited on plastic film, or metal, plastic film or paper with conductive material alone or with binder resin And those provided with a conductive layer.

<Intermediate layer>
The intermediate layer 102 is provided between the conductive support 101 and the photosensitive layer 103, and has a barrier function and an adhesive function. The intermediate layer 102 uses a liquid (intermediate layer forming liquid) in which a binder resin such as casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyamide, polyurethane, or gelatin is dissolved in a known solvent. It is preferably formed by a dip coating method or the like. As the binder resin, it is preferable to use an alcohol-soluble polyamide resin. The thickness of the intermediate layer 102 is preferably 0.1 μm or more and 15 μm or less, and more preferably 0.3 μm or more and 10 μm or less.

  The intermediate layer 102 preferably contains inorganic particles such as various conductive particles or various metal oxide particles for the purpose of adjusting resistance. Examples of the inorganic particles include particles made of alumina, zinc oxide, titanium oxide, tin oxide, antimony oxide, indium oxide, bismuth oxide, etc., and tin-doped indium oxide, antimony-doped oxide. Examples thereof include particles made of tin, zirconium oxide, or the like. As the inorganic particles, these particles can be used alone or in admixture of two or more. When these particles are used in combination of two or more, they may take the form of a solid solution or the form of fusion. The inorganic particles preferably have a number average primary particle size of 0.3 μm or less, and more preferably a number average primary particle size of 0.1 μm or less.

  Examples of the solvent (solvent included in the intermediate layer forming liquid) that can be used to form the intermediate layer 102 include those that disperse the inorganic particles well and dissolve binder resins such as polyamide resins. Preferably there is. Specifically, alcohols having 2 to 4 carbon atoms such as ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol, t-butanol, or sec-butanol are preferably used. These alcohols have a good solubility in a polyamide resin suitable as a binder resin, and impart good coating performance to the intermediate layer forming liquid.

  In order to improve the storage stability of the electrophotographic photoreceptor 100 and the dispersibility of the inorganic particles, it is preferable to use a cosolvent in combination with the above solvent. Examples of the co-solvent that can provide a preferable effect include methanol, benzyl alcohol, toluene, cyclohexanone, and tetrahydrofuran.

  The concentration of the binder resin in the intermediate layer forming liquid is preferably appropriately selected according to the thickness of the intermediate layer 102 or the application method of the intermediate layer forming liquid. When the inorganic particles are dispersed in the intermediate layer forming liquid, the inorganic particles are preferably added in an amount of 20 parts by mass or more and 400 parts by mass or less, and 50 parts by mass or more and 200 parts by mass or less with respect to 100 parts by mass of the binder resin. More preferably.

  Examples of the means for dispersing the inorganic particles include, but are not limited to, an ultrasonic disperser, a ball mill, a sand grinder, or a homomixer.

  The method for drying the coating film made of the intermediate layer forming liquid is preferably selected as appropriate depending on the type of the solvent contained in the intermediate layer forming liquid, the thickness of the intermediate layer 102, etc. More preferably.

<Photosensitive layer>
The photosensitive layer 103 may be formed of a single layer having both a charge generation function and a charge transport function. However, the photosensitive layer 103 includes a charge generation layer 104 and a charge transport layer 105 provided on the charge generation layer 104. It is preferable to have. Since the photosensitive layer 103 includes the charge generation layer 104 and the charge transport layer 105, it is possible to prevent the residual potential from increasing due to repeated use of the electrophotographic photosensitive member 100, and to control the electrophotographic characteristics according to the purpose.

(Charge generation layer)
The charge generation layer 104 preferably includes a charge generation material and a binder resin, and a dispersion liquid (charge generation layer forming liquid) in which the charge generation material is dispersed in a binder resin solution is applied to the upper surface of the intermediate layer 102. It is preferable to be formed. The thickness of the charge generation layer 104 varies depending on the characteristics of the charge generation material, the characteristics of the binder resin, or the mixing ratio of the charge generation material and the binder resin. It is preferable that it is 0.05 μm or more and 3 μm or less.

  Examples of the charge generation material include azo raw materials such as Sudan Red or Diane Blue, quinone pigments such as pyrenequinone or anthanthrone, quinocyanine pigments, perylene pigments, indigo pigments such as indigo or thioindigo, or phthalocyanine pigments. It is not limited to these. As the charge generating substance, these can be used alone or in a form dispersed in a known binder resin.

  As the binder resin, known resins can be used, for example, polystyrene resin, polyethylene resin, polypropylene resin, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, polyvinyl butyral resin, epoxy resin, polyurethane resin, phenol resin, A polyester resin, an alkyd resin, a polycarbonate resin, a silicone resin, a melamine resin, or the like can be used, and a copolymer resin containing two or more of these resins (for example, a copolymer resin of vinyl chloride and vinyl acetate) Or a copolymer resin of vinyl chloride, vinyl acetate, and maleic anhydride). Moreover, as a binder resin, you may use poly-vinyl carbazole resin etc., It does not specifically limit.

  The charge generation material is preferably added in an amount of 1 part by mass or more and 600 parts by mass or less, and more preferably 50 parts by mass or more and 500 parts by mass or less, relative to 100 parts by mass of the binder resin.

  The charge generation layer 104 is preferably formed according to the following method. First, using a disperser, the charge generating material is dispersed in a binder resin solution (in this solution, the binder resin is dissolved in a solvent). In this way, the charge generation layer forming liquid is prepared. Next, after applying the charge generation layer forming liquid to the upper surface of the intermediate layer 102 with a certain thickness using a coating machine, the formed coating film is dried. In this way, the charge generation layer 104 can be formed. In addition, it is preferable to filter the charge generation layer forming liquid and filter out foreign matters or aggregates before applying the charge generation layer forming liquid. Thereby, generation | occurrence | production of an image defect can be prevented.

  Examples of the solvent for dissolving the binder resin include toluene, xylene, methyl ethyl ketone, cyclohexane, ethyl acetate, butyl acetate, methanol, ethanol, propanol, butanol, methyl cellosolve, ethyl cellosolve, tetrahydrofuran, 1-dioxane, 1, 3 -Examples include, but are not limited to, dioxolane, pyridine, or diethylamine.

  Examples of the means for dispersing the charge generation material include, but are not limited to, an ultrasonic disperser, a ball mill, a sand grinder, and a homomixer.

(Charge transport layer)
The charge transport layer 105 preferably includes at least a charge transport material and a binder resin, and a solution (charge transport layer forming liquid) in which the charge transport material is dissolved in the binder resin solution is formed on the upper surface of the charge generation layer 104. It is preferably formed by coating. The thickness of such a charge transport layer 105 varies depending on the characteristics of the charge transport material, the characteristics of the binder resin, or the mixing ratio of the charge transport material and the binder resin, but cannot be generally stated, but it is 5 μm or more and 40 μm or less. Is preferably 10 μm or more and 30 μm or less.

  Examples of the charge transport material include carbazole derivatives, oxazole derivatives, oxadiazole derivatives, thiazole derivatives, thiadiazole derivatives, triazole derivatives, imidazole derivatives, imidazolone derivatives, imidazolidine derivatives, bisimidazolidine derivatives, styryl compounds, hydrazone compounds, pyrazolines. Compound, oxazolone derivative, benzimidazole derivative, quinazoline derivative, benzofuran derivative, acridine derivative, phenazine derivative, aminostilbene derivative, triarylamine derivative, phenylenediamine derivative, stilbene derivative, benzidine derivative, poly-N-vinylcarbazole, poly-1 -Vinylpyrene, poly-9-vinylanthracene, etc. are mentioned. These can be used alone or in combination of two or more as the charge transport material.

  As the binder resin, a known resin can be used. For example, polycarbonate resin, polyacrylate resin, polyester resin, polystyrene resin, styrene-acrylonitrile copolymer resin, polymethacrylic ester resin, or styrene-methacrylic ester copolymer. Polymer resin etc. are mentioned. Among these, polycarbonate resin is preferable. From the viewpoint of crack resistance, abrasion resistance, and charging characteristics, among polycarbonate resins, bisphenol A (BPA (bisphenol A)), bisphenol Z (BPZ (bisphenol Z)), dimethyl BPA, or BPA More preferred is a copolymer with dimethyl BPA.

  The charge transport material is preferably added in an amount of 10 to 500 parts by mass, more preferably 20 to 100 parts by mass, with respect to 100 parts by mass of the binder resin. The charge transport layer 105 may further contain a known antioxidant described in, for example, Japanese Patent Application Laid-Open No. 2000-305291.

  The charge transport layer 105 is preferably formed according to the following method. First, a charge transport material and a binder resin are dissolved in a solvent to obtain a charge transport layer forming liquid. Next, after the charge transport layer forming liquid is applied to the upper surface of the charge generation layer 104 with a certain thickness, the formed coating film is dried. In this way, the charge transport layer 105 can be formed.

  Examples of the solvent for dissolving the charge transport material and the binder resin include toluene, xylene, methyl ethyl ketone, cyclohexanone, ethyl acetate, butyl acetate, methanol, ethanol, propanol, butanol, tetrahydrofuran, 1,4-dioxane, or 1, Examples include, but are not limited to, 3-dioxolane.

[Configuration of electrophotographic image forming apparatus, image forming method]
The electrophotographic image forming apparatus of the present embodiment (hereinafter sometimes simply referred to as “image forming apparatus”) includes an electrophotographic photosensitive member 100, a charging unit that charges the surface of the electrophotographic photosensitive member 100, and an electrophotographic photosensitive member. An exposure unit that forms an electrostatic latent image on the surface of the body 100 and a developing unit that develops the electrostatic latent image with toner to form a toner image are provided. Since the image forming apparatus of the present embodiment includes the electrophotographic photosensitive member 100, the abrasion resistance of the electrophotographic photosensitive member 100 can be maintained high, the difference in image density (image memory) depending on the photosensitive member cycle is improved, and the fog resistance is improved. Become stronger.

  The process cartridge according to this embodiment is detachably attached to the image forming apparatus, and includes an electrophotographic photoreceptor 100, a charging unit that charges the surface of the electrophotographic photoreceptor 100, and an electrostatic latent image on the surface of the electrophotographic photoreceptor 100. An exposure unit that forms an image and a developing unit that develops the electrostatic latent image with toner to form a toner image. Since the process cartridge of the present embodiment includes the electrophotographic photosensitive member 100, the abrasion resistance of the electrophotographic photosensitive member 100 can be maintained high, the image density difference (image memory) depending on the photosensitive member cycle becomes good, Increases fog resistance. Hereinafter, this will be specifically described with reference to FIG.

  FIG. 2 is a cross-sectional view illustrating a configuration of the image forming apparatus according to the present exemplary embodiment. The image forming apparatus shown in FIG. 2 is called a tandem color image forming apparatus, and includes four sets of image forming units (process cartridges) 10Y, 10M, 10C, and 10Bk, and an endless belt-shaped intermediate transfer member unit 7. And a sheet feeding / conveying unit 21 and a fixing unit 24. A document image reading device SC is disposed on the upper part of the apparatus main body A.

  The image forming unit 10Y forms a yellow image. The image forming unit 10Y includes a charging unit 2Y, an exposure unit 3Y, a developing unit 4Y, and a cleaning unit 6Y arranged around a drum-shaped electrophotographic photoreceptor 1Y, and further includes a primary transfer roller 5Y.

  The image forming unit 10M forms a magenta image. The image forming unit 10M includes a charging unit 2M, an exposure unit 3M, a developing unit 4M, and a cleaning unit 6M around a drum-shaped electrophotographic photosensitive member 1M, and further includes a primary transfer roller 5M.

  The image forming unit 10C forms a cyan image. The image forming unit 10C includes a charging unit 2C, an exposure unit 3C, a developing unit 4C, and a cleaning unit 6C around the drum-shaped electrophotographic photosensitive member 1C, and further includes a primary transfer roller 5C.

  The image forming unit 10Bk forms a black image. The image forming unit 10Bk includes a charging unit 2Bk, an exposure unit 3Bk, a developing unit 4Bk, and a cleaning unit 6Bk arranged around a drum-shaped electrophotographic photosensitive member 1Bk, and further includes a primary transfer roller 5Bk.

  If the electrophotographic photoreceptor 100 is used as at least one of the drum-shaped electrophotographic photoreceptor 1Y, the drum-shaped electrophotographic photoreceptor 1M, the drum-shaped electrophotographic photoreceptor 1C, and the drum-shaped electrophotographic photoreceptor 1Bk. The above-described effects (the abrasion resistance of the electrophotographic photosensitive member 100 can be maintained high, the image density difference (image memory) depending on the photosensitive member period is good, and the fog resistance is strong) can be obtained.

  The image forming units 10Y, 10M, 10C, and 10Bk are configured similarly except that the colors of the toner images formed on the electrophotographic photoreceptors 1Y, 1M, 1C, and 1Bk are different. For this reason, the image forming unit 10Y will be described below as an example.

  In the present embodiment, at least the electrophotographic photoreceptor 1Y, the charging unit 2Y, the developing unit 4Y, and the cleaning unit 6Y are integrated in the image forming unit 10Y.

  The charging unit 2Y applies a uniform potential to the electrophotographic photoreceptor 1Y to charge (for example, negatively charge) the surface of the electrophotographic photoreceptor 1Y. As the charging unit 2Y, a non-contact charger is preferably used. For example, a corona charger such as a corotron charger or a scorotron charger can be used.

  The exposure unit 3Y exposes the surface of the electrophotographic photoreceptor 1Y to which the uniform potential is applied by the charging unit 2Y based on the image signal (yellow), and thereby, the static corresponding to the yellow image. An electrostatic latent image is formed. The exposure unit 3Y includes an LED configured by arranging light emitting elements in an array in the axial direction of the electrophotographic photoreceptor 1Y and an imaging element (trade name; SELFOC (registered trademark) lens), or A laser optical system or the like can be used.

  The developing unit 4Y develops the electrostatic latent image formed by the exposure unit 3Y with toner to form a toner image. The toner to be used is not particularly limited, but is preferably a dry developer.

  In the image forming apparatus of the present embodiment, the electrophotographic photosensitive member 1Y, the charging unit 2Y, the exposure unit 3Y, the developing unit 4Y, the cleaning unit 6Y, and the like are integrated as a process cartridge. On the other hand, it may be detachably mounted. Further, at least one of the charging unit 2Y, the exposure unit 3Y, the developing unit 4Y, the transfer or separator, and the cleaning unit 6Y is integrally supported together with the electrophotographic photosensitive member 1Y to form a process cartridge, and the process cartridge Is configured as a single image forming unit that can be attached to and detached from the apparatus main body A, and the single image forming unit is detachably attached to the apparatus main body A using a guide means such as a rail of the apparatus main body A. Also good.

  The housing 8 having the image forming units 10Y, 10M, 10C, and 10Bk and the endless belt-shaped intermediate transfer body unit 7 is configured to be drawable from the apparatus main body A by support rails 82L and 82R. In the housing 8, the image forming units 10Y, 10M, 10C, and 10Bk are arranged in a vertical row in the vertical direction. The endless belt-like intermediate transfer body unit 7 is disposed on the left side of the photoreceptors 1Y, 1M, 1C, and 1Bk in FIG. 2, and is an endless belt that can be rotated by winding rollers 71, 72, 73, and 74. Intermediate transfer body 70, primary transfer rollers 5Y, 5M, 5C, and 5Bk, and a cleaning unit 6b.

  Hereinafter, an image forming method using the image forming apparatus shown in FIG. 2 will be described. Each color image formed by the image forming units 10Y, 10M, 10C, and 10Bk is sequentially transferred onto a rotating endless belt-shaped intermediate transfer body 70 by primary transfer rollers 5Y, 5M, 5C, and 5Bk. Thereby, a synthesized color image is formed.

  A transfer material (for example, plain paper, transparent sheet, etc.) P accommodated in the paper feed cassette 20 is fed by a paper feed / conveying section 21 and passes through a plurality of intermediate rollers 22A, 22B, 22C, 22D and a registration roller 23. Then, it is conveyed to the secondary transfer roller 5b. In the secondary transfer roller 5b, the combined color image is secondarily transferred to the transfer material P, and thus the color image is transferred to the transfer material P all at once. When the combined color image is secondarily transferred onto the transfer material P, the endless belt-shaped intermediate transfer body 70 separates the transfer material P by curvature. The transfer material P is fixed by the fixing unit 24, sandwiched between the paper discharge rollers 25, and placed on the paper discharge tray 26 outside the apparatus. On the other hand, the toner (residual toner) adhering to the intermediate transfer member 70 is removed by the cleaning unit 6b.

  During image formation, the primary transfer roller 5Bk is always in contact with the surface of the electrophotographic photoreceptor 1Bk. On the other hand, the primary transfer rollers 5Y, 5M, and 5C are in contact with the surfaces of the corresponding electrophotographic photoreceptors 1Y, 1M, and 1C only during color image formation. The secondary transfer roller 5b contacts the surface of the endless belt-shaped intermediate transfer body 70 only when the transfer material P passes through the secondary transfer roller 5b and secondary transfer is performed.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to the following.
<Example 1>
An electrophotographic photosensitive member was produced according to the following method. First, the electroconductive support body by which the cutting process was given to the surface of the cylindrical aluminum support body was prepared.

(Formation of intermediate layer)
In a wet sand mill (a container is filled with alumina beads having a diameter of 0.5 mm), 1.0 part by mass of polyamide resin (binder resin, product number “X1010” manufactured by Daicel Evonik Co., Ltd.) and titanium dioxide particles ( 1.1 parts by mass (product number “SMT500SAS” manufactured by Teika Co., Ltd.) and 20 parts by mass of ethanol (solvent) were added and dispersed in a batch system for 10 hours. In this way, an intermediate layer forming liquid was obtained.

  A film made of the intermediate layer forming liquid was formed on the upper surface of the conductive support by a dip coating method, and then dried at 110 ° C. for 20 minutes. In this way, an intermediate layer having a thickness (thickness after drying) of 2 μm was formed on the upper surface of the conductive support.

(Formation of charge generation layer)
At least 2θ = 27.3 as determined by measuring an X-ray diffraction spectrum using a titanyl phthalocyanine pigment (charge generation material, characteristic X-ray (Cu—Kα ray)) in a wet sand mill of the same type as the wet sand mill used for forming the intermediate layer. 20 parts by mass of titanyl phthalocyanine pigment having a maximum diffraction peak at the position of °, 10 parts by mass of polyvinyl butyral resin (binder resin, product number “# 6000-C” manufactured by Denki Kagaku Kogyo Co., Ltd.), and t-butyl acetate ( Solvent) 700 parts by mass and 4-methoxy-4-methyl-2-pentanone (solvent) 300 parts by mass were added and dispersed for 10 hours. In this way, a charge generation layer forming liquid was obtained.

  A film made of the charge generation layer forming liquid was formed on the upper surface of the intermediate layer by a dip coating method and then dried. Thus, a charge generation layer having a thickness (thickness after drying) of 0.3 μm was formed on the upper surface of the intermediate layer.

(Formation of charge transport layer)
In a wet sand mill of the same type as the wet sand mill used for forming the intermediate layer and the like, 150 parts by mass of a compound (charge transport material) represented by the following chemical formula (18) and a polycarbonate resin (binder resin, manufactured by Mitsubishi Gas Chemical Co., Ltd.) 300 parts by mass of product number “Z300”), 6 parts by mass of antioxidant (product number “Irganox (registered trademark) 1010” manufactured by BASF Japan Ltd.), and a mixed solvent of toluene and tetrahydrofuran ((toluene): (tetrahydrofuran)) = 1: 9 (volume ratio)) 2000 parts by mass and silicone oil (additive, product number “KF-54” manufactured by Shin-Etsu Chemical Co., Ltd.) 1 part by mass are added, and the charge transport material and the binder resin are added. It was dissolved in a mixed solvent. In this way, a charge transport layer forming liquid was obtained.

  A film made of the charge transport layer forming liquid was formed on the upper surface of the charge generation layer by dip coating, and then dried at 110 ° C. for 60 minutes. Thus, a charge transport layer having a thickness (thickness after drying) of 20 μm was formed on the upper surface of the charge generation layer.

(Preparation of p-type semiconductor particles)
In a wet sand mill of the same type as the wet sand mill used for forming the intermediate layer and the like, 100 parts by mass of CuAlO ₂ (p-type semiconductor particles) having a number average primary particle size of 20 nm and the compound (surface) described above in S-15 (Treatment agent) 10 parts by mass and 1000 parts by mass of methyl ethyl ketone were added and mixed at 30 ° C. for 6 hours. Thereafter, methyl ethyl ketone and alumina beads were separated by filtration and dried at 60 ° C. In this way, surface-treated p-type semiconductor particles were obtained.

(Formation of surface protective layer)
162 parts by mass of surface-treated p-type semiconductor particles and ZrO ₂ particles (product number “TZ-B30” manufactured by Tosoh Corporation) 0.5 mass in the same type as the wet sand mill used for forming the intermediate layer, etc. Part, 100 parts by mass of the compound represented by the chemical formula (1) (curable compound) and 320 parts by mass of 2-butanone (solvent) were added and dispersed for 10 hours.

  Next, 80 parts by mass of tetrahydrofuran and 8 parts by mass of bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide (polymerization initiator, product number “IRGACURE 819” manufactured by BASF Japan Ltd.) are added to the wet sand mill. Was further mixed and stirred in the dark. In this way, a surface layer forming liquid was obtained. The surface layer forming liquid was handled under light shielding until the light from the metal halide lamp described later was irradiated to the surface layer forming liquid.

  Next, the surface layer forming liquid was applied to the upper surface of the charge transport layer using a circular slide hopper applicator. The formed coating film was dried at room temperature for 20 minutes. Thereafter, the light from the metal halide lamp (output: 500 W) is rotated while rotating the structure on which the coating film is formed (the structure in which the intermediate layer and the photosensitive layer are sequentially formed on the conductive support). Was irradiated to the coating film for 1 minute from a position 100 mm away from the surface of the coating film. Thus, a surface layer having a thickness of 3 μm (thickness after drying) was formed, and thus the electrophotographic photosensitive member of this example was obtained.

<Examples 2 to 14, Comparative Example 1 and Comparative Example 2>
The method described in Example 1 except that the material of the p-type semiconductor particles, the blending amount of the p-type semiconductor particles, the material of the first particles or the blending amount of the first particles are changed as shown in Table 1. Therefore, an electrophotographic photosensitive member was obtained.

<Example 15>
According to the method described in Example 1, an intermediate layer and a charge generation layer were formed. After preparing the charge transport layer forming liquid according to the method described in Example 1, a film made of the charge transport layer forming liquid was formed on the upper surface of the charge generation layer by dip coating. Then, the liquid for surface layer formation was prepared according to the method shown next, without performing drying at 110 degreeC.

First, according to the method described in Example 1, surface-treated p-type semiconductor particles were produced. Next, 162 parts by mass of the surface-treated p-type semiconductor particles, 0.5 parts by mass of ZrO ₂ particles (product number “TZ-B30” manufactured by Tosoh Corporation) and polycarbonate are used in the wet sand mill used in Example 1. 200 parts by mass of resin (binder resin, product number “Z300” manufactured by Mitsubishi Gas Chemical Co., Ltd.) and silica particles (silica particles surface-treated with 25% by mass of methylhydrogenpolysiloxane based on the mass of silica, this silica Mixing of 20 parts by mass of the median diameter D50 when the particle size distribution of the particles is measured on a number basis is 31 nm), 20 parts by mass of an antioxidant (product number “Irganox 1010” manufactured by Ciba Japan Co., Ltd.), tetrahydrofuran and toluene. 6000 parts by mass of a solvent ((tetrahydrofuran) :( toluene) = 4: 1 (volume ratio)) and silicone oil ( Yue Chemical Industry Co., Ltd .: product number "KF-96") were placed and 1 part by weight, mixed and stirred. In this way, a surface layer forming liquid was obtained.

  A film made of the surface layer forming liquid was formed on the film made of the charge transport layer forming liquid by a dip coating method, and then dried at 120 ° C. for 70 minutes. Thus, a charge transport layer having a thickness (thickness after drying) of 20 μm and a surface layer having a thickness (thickness after drying) of 5 μm are formed. A photoreceptor was obtained.

In Table 1, “curable resin ^{* 11} ” means a resin obtained by curing the compound (curable compound) represented by the chemical formula (1). “Mixed amount ^{* 12} ” means the ratio (volume ratio) of the surface-treated p-type semiconductor particles to the total composition constituting the surface layer. “Blend amount ^{* 13} ” means the ratio (mass ratio) of the first particles to the p-type semiconductor particles. “Blend amount ^{* 14} ” means the ratio (mass ratio) of TiO ₂ particles to p-type semiconductor particles.

  In addition, the present inventors are included in the surface layer of each electrophotographic photoreceptor of Examples 1 to 15 using a sequential X-ray fluorescence analyzer (product number “XRF-1700” manufactured by Shimadzu Corporation). When the material of the first particle and the content of the first particle were examined, it was confirmed that the amount was the same as the amount of the first particle material and the first particle shown in Table 1.

<Evaluation>
(Print life test)
First, each of the electrophotographic photosensitive members of Examples 1 to 15, Comparative Example 1 and Comparative Example 2 was incorporated as an electrophotographic photosensitive member of an image forming apparatus (product number “bizhub C6501” manufactured by Konica Minolta Business Technologies, Inc.). . Next, a printing durability test was performed in a high temperature and high humidity environment (30 ° C. and 85% RH (relative humidity)). In the printing durability test, a full-color image in which the printing ratio of each of a yellow image, a magenta image, a cyan image, and a black image was 2.5% was printed on one side on 700,000 sheets of neutral paper of A4 size.

(Evaluation of image memory)
After the printing durability test, A4 size high-quality paper was placed in the paper feed cassette so that it could be “transversely fed”. On 10 sheets of the high-quality paper, images having a black solid image on the left half in the paper passing direction and a white solid image on the right half in the paper passing direction were continuously printed.

  Next, a uniform halftone image was printed. Using a densitometer (product number “RD-918” manufactured by Gretag Macbeth Co., Ltd.), the reflection density of the region corresponding to the black solid image in the printed halftone image, and the white solid image in the halftone image The reflection density of the area was measured. Two measured reflection density differences (ΔID) were calculated. The results are shown in Table 1.

  In Table 1, “A1” is written when ΔID is 0.05 or less, and “B1” is written when ΔID is more than 0.05 and 0.10 or less. The smaller the ΔID, the less the black solid image history and the white solid image history appear in the printed halftone image, and thus the better the image density difference (image memory) due to the photoreceptor cycle. It means that. The inventors of the present invention have determined that practical use as an electrophotographic photosensitive member is possible when “A1” and “B1” in Table 1. Therefore, Examples 1 to 15, Comparative Example 1 and Comparative Example In both cases, the image memory was good.

(Α value)
Prior to incorporating the electrophotographic photosensitive member into the image forming apparatus, the thickness of the electrophotographic photosensitive member was measured. Specifically, a portion having a uniform thickness (the thickness tends to be non-uniform at the axial end portion of the electrophotographic photosensitive member, so that the axial end surface of the electrophotographic photosensitive member extends inward in the axial direction of the electrophotographic photosensitive member. Ten thickness measurement points were selected at random, except for a portion within 3 cm). Measure the thickness at the measurement point using an eddy current type film thickness measuring instrument (part number “EDDY560C” manufactured by Helmut Fischer), and calculate the average thickness (thickness before the endurance test). Calculated.

Next, after the electrophotographic photosensitive member was incorporated in the image forming apparatus, the printing durability test was performed. Thereafter, the electrophotographic photosensitive member was taken out from the image forming apparatus, and the thickness after the durability test was calculated according to the method for obtaining the thickness before the durability test. The amount of film thickness wear was determined using the following equation, and the amount of wear (α value) per 100 krot (100,000 revolutions) was determined. The results are shown in Table 1. A smaller α value means that the electrophotographic photoreceptor is more excellent in abrasion resistance.
(Amount of film thickness loss) = (Thickness before durability test) − (Thickness after durability test).

(Evaluation of fogging)
After the printing durability test, the electrophotographic photoreceptors of Examples 1 to 15, Comparative Example 1 and Comparative Example 2 were used only as the electrophotographic photoreceptor of the black image forming portion. After that, the POD gloss coated paper on which no image is formed is conveyed to the position of the primary transfer roller in the black image forming unit, and then -800V is applied as the grid voltage and -650V is applied as the developing bias. A yellow solid image was formed on the paper. The fogging evaluation of black in POD gloss coated paper was performed according to the following criteria. The results are shown in Table 1.

  In Table 1, “A2” is indicated when fog is not confirmed in the visual evaluation, “B2” is indicated when fog is slightly confirmed when magnified, and when fog is confirmed visually. “C2” and “D2” when fog is noticeable. The inventors of the present invention have determined that practical use as an electrophotographic photosensitive member is possible when “A2” and “B2” in Table 1.

<Discussion>
In Examples 1 to 15, Comparative Example 1 and Comparative Example 2, the image memory was good. Further, it is considered that the α value is small, and therefore the wear resistance of the electrophotographic photosensitive member is maintained high. In Examples 1 to 15, Comparative Example 1 and Comparative Example 2, the surface layer contains p-type semiconductor particles. Therefore, it is considered that the above results were obtained.

However, in Examples 1 to 15, the fog resistance was strong, whereas in Comparative Examples 1 and 2, the fog resistance deteriorated. In Comparative Example 1, the surface layer does not contain any first particles. Therefore, it is considered that the above results were obtained. In Comparative Example 2, the surface layer includes TiO ₂ particles instead of the first particles. The present inventors believe that the above results were obtained because the TiO ₂ particles have lower resistance than the ZrO ₂ particles, SiO ₂ particles, and Al ₂ O ₃ particles.

  In Examples 1 to 15, Comparative Example 1 and Comparative Example 2, the results relating to the evaluation of the image memory were not significantly different, and the results relating to the abrasion resistance of the electrophotographic photosensitive member were not significantly different. Therefore, it has been found that when the surface layer includes the p-type semiconductor particles and the first particles, the anti-fogging resistance is enhanced while maintaining the effect obtained when the surface layer includes the p-type semiconductor particles.

In Examples 1 to 3, the fog resistance was strong. From this result, it was found that the fog resistance is enhanced even when any of ZrO ₂ particles, SiO ₂ particles, or Al ₂ O ₃ particles is used as the first particles. In the viewpoint of improving the image memory, it has been found that it is preferable to use a ZrO ₂ particles as the first particles.

  In Examples 4, 5 and 7, the fog resistance was stronger than in Examples 6 and 8. From this result, it was found that when the content of the first particles is 0.05% by mass or more and 5% by mass or less, the fog resistance is further enhanced.

In Examples 9 to 15, the fog resistance was strong. From this result, it was found that the anti-fogging resistance is enhanced regardless of the material of the p-type semiconductor particles. From the viewpoint of improving the image memory, it has been found that it is preferable to use CuAlO ₂ particles, CuGaO ₂ particles, SrCu ₂ O ₂ particles or BaCu ₂ O ₂ particles as the p-type semiconductor particles.

  In Examples 1 to 14, the α value could be further reduced as compared with Example 15. From this result, it was found that the resin constituting the surface layer preferably contains a component obtained by curing of the curable compound from the viewpoint of enhancing the abrasion resistance of the electrophotographic photosensitive member.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  100 electrophotographic photosensitive member, 101 conductive support, 102 intermediate layer, 103 photosensitive layer, 104 charge generation layer, 105 charge transport layer, 106 surface layer.

Claims (8)

An electrophotographic photosensitive member comprising a conductive support, and a photosensitive layer and a surface layer sequentially provided on the conductive support,
The surface layer is an electrophotographic photoreceptor including p-type semiconductor particles and first particles that are at least one of zirconium dioxide particles, silicon dioxide particles, and aluminum oxide particles.   2. The electrophotographic photosensitive member according to claim 1, wherein in the surface layer, the content of the first particles is 0.05% by mass or more and 5% by mass or less of the content of the p-type semiconductor particles.   The electrophotographic photosensitive member according to claim 1, wherein the first particles are the zirconium dioxide particles.   The electrophotographic photosensitive member according to claim 1, wherein the p-type semiconductor particles are made of a metal oxide. The p-type semiconductor particles are composed of at least one of a metal oxide represented by the following general formula (1) and a metal oxide represented by the following general formula (2). The electrophotographic photosensitive member according to any one of the above.
Cu (M1) O ₂ General formula (1)
(M2) Cu ₂ O ₂ ... General formula (2)
M1 in the general formula (1) represents a Group 13 element in the periodic table, and M2 in the general formula (2) represents a Group 2 element in the periodic table.   The electrophotographic photosensitive member according to claim 1, wherein the surface layer further includes a component obtained by curing a curable compound. The electrophotographic photosensitive member according to claim 1,
A charging unit for charging the surface of the electrophotographic photosensitive member;
An exposure part for forming an electrostatic latent image on the surface of the electrophotographic photosensitive member;
An electrophotographic image forming apparatus comprising: a developing unit that develops the electrostatic latent image with toner to form a toner image. Removably attached to the electrophotographic image forming apparatus,
The electrophotographic photosensitive member according to claim 1,
A charging unit for charging the surface of the electrophotographic photosensitive member;
An exposure part for forming an electrostatic latent image on the surface of the electrophotographic photosensitive member;
A process cartridge comprising: a developing unit that develops the electrostatic latent image with toner to form a toner image.

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