JP6183026B2 - Electrophotographic photoreceptor and image forming apparatus - Google Patents

Description

  The present invention relates to an electrophotographic photoreceptor and an image forming apparatus provided in an electrophotographic image forming apparatus.

  Conventionally, an inorganic photoreceptor and an organic photoreceptor are known as an electrophotographic photoreceptor (hereinafter also simply referred to as “photoreceptor”) used in an electrophotographic image forming apparatus. The “electrophotographic method” here generally means that a photoconductive photosensitive member is first charged in a dark place, for example, by corona discharge, and then subjected to image exposure, whereby the charge of only the exposed portion is selectively dissipated and static. This is an image forming process in which an electrostatic latent image is obtained, the latent image portion is developed with a toner composed of a colorant such as a dye and a pigment, and a resin material, and visualized to form an image.

Compared to inorganic photoreceptors, organic photoreceptors have advantages in terms of freedom of photosensitive wavelength range, film formability, flexibility, film transparency, mass productivity, toxicity, cost, etc. An organic photoreceptor is used for the body.
An organic photoreceptor that is repeatedly used in this electrophotographic image forming process is required to have high durability and excellent potential characteristics.

In such a photoconductor, a method of roughening the surface of the photoconductor is known for improving the cleaning property.
For example, Patent Documents 1 and 2 disclose a photoreceptor in which composite fine particles in which a conductive metal oxide is attached to the surface of barium sulfate are added to the surface layer. Since the composite fine particles can be produced with a relatively large particle size (50 to 500 nm), the surface of the photoreceptor can be appropriately roughened. Accordingly, such a photoreceptor has improved cleaning properties and wear resistance as compared with a photoreceptor having a surface layer to which no composite fine particles are added.
However, this composite fine particle has a low volume resistivity of about 10 ⁰ to 10 ³ [Ωcm], and there is a problem that if the addition amount is increased, image flow occurs after exposure writing.

JP-A-6-295086 JP-A-6-250430

  The present invention has been made in consideration of the above-described circumstances, and an object of the present invention is to provide electrophotography that has high durability and suppresses the occurrence of image flow while ensuring good cleaning properties. An object of the present invention is to provide a photoreceptor and an image forming apparatus provided with the electrophotographic photoreceptor.

In the electrophotographic photosensitive member of the present invention, a photosensitive layer is formed on a conductive support, and a surface layer is formed on the photosensitive layer.
The surface layer is formed by attaching a conductive metal oxide to the surface of a core material made of an insulating material in a cured resin obtained by polymerizing a compound having two or more radically polymerizable functional groups. a volume resistivity of 10 ^-3 to 10 ⁷ [Ωcm], composite fine particles having an average particle diameter of 50 to 300 nm, and state, and are not charge-transporting compound is in a content,
The core material in the composite fine particles is at least one selected from barium sulfate, alumina and silica,
The conductive metal oxide in the composite fine particles is at least one selected from tin oxide, titanium oxide, zinc oxide, zirconia and indium tin oxide,
When the conductive metal oxide is tin oxide composite fine particles, the composite fine particles are surface-treated with a surface treatment agent comprising a compound having a radical polymerizable functional group .

In the electrophotographic photosensitive member of the present invention, the number density of the composite fine particles per unit volume of the surface layer is preferably 1 to 550 [pieces / μm ³ ].

  In the electrophotographic photoreceptor of the present invention, the charge transporting compound is preferably represented by the following general formula (1).

[In General Formula (1), R ¹ and R ² are each independently a hydrogen atom or a methyl group, and R ³ is a linear or branched alkyl group having 1 to 5 carbon atoms. ]

In the electrophotographic photoreceptor of the present invention, the core material in the composite particles is preferably a barium sulfate.

  In the electrophotographic photosensitive member of the present invention, the radical polymerizable functional group in the surface treatment agent is preferably an acryloyl group or a methacryloyl group.

The image forming apparatus of the present invention includes an electrophotographic photosensitive member, 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 the electrostatic unit. Developing means for developing a latent image with toner to form a toner image, transfer means for transferring the toner image to a transfer material, fixing means for fixing the toner image transferred to the transfer material, and an electrophotographic photosensitive member Cleaning means for removing the residual toner on the top,
The electrophotographic photosensitive member is the above-described electrophotographic photosensitive member.
In the image forming apparatus of the present invention, the cleaning unit is preferably a blade.

  According to the electrophotographic photoreceptor of the present invention, the surface layer is a composite having a specific volume resistivity and a specific average particle diameter, in which a conductive metal oxide is attached to the surface of a core material made of an insulating material. Since the fine particles and the charge transporting compound are contained in the cured resin, the occurrence of image flow is suppressed while having high durability and ensuring good cleaning properties.

  According to the image forming apparatus of the present invention, a high-quality image can be formed over a long period of time by including the electrophotographic photosensitive member.

It is sectional drawing for description which shows the structure in an example of the surface layer which comprises the photoreceptor of this invention. It is sectional drawing for description which shows an example of a structure of the circular slide hopper coating device used for the manufacturing method of the photoreceptor of this invention. It is a perspective sectional view of the circular slide hopper coating device shown in FIG. 1 is a cross-sectional view illustrating the configuration of an example of an image forming apparatus according to the present invention. FIG. 3 is an explanatory cross-sectional view illustrating a configuration of an example of a cleaning unit in the image forming apparatus of the present invention. It is the schematic for description which shows the structure of the apparatus for manufacturing the composite microparticles | fine-particles which concern on this invention.

  Hereinafter, the present invention will be described in detail.

[Electrophotographic photoconductor]
The photoreceptor of the present invention is not particularly limited as long as the photosensitive layer and the surface layer are laminated in this order on the conductive support. Specifically, the following (1) and (2) layer configurations Is mentioned.
(1) A layer structure in which a charge generation layer, a charge transport layer, and a surface layer are laminated in this order as an intermediate layer and a photosensitive layer on a conductive support.
(2) A layer structure in which an intermediate layer, a single layer containing a charge generation material and a charge transport material as a photosensitive layer, and a surface layer are laminated in this order on a conductive support.

  The photoconductor of the present invention is an organic photoconductor, and an electrophotographic photoconductor in which at least one of a charge generation function and a charge transport function essential to the configuration of an electrophotographic photoconductor is expressed by an organic compound. And a photoreceptor composed of a known organic charge generation material or organic charge transport material, a photoreceptor composed of a polymer complex with a charge generation function and a charge transport function, and the like.

[Surface layer]
The surface layer constituting the photoreceptor of the present invention is formed on the photosensitive layer and has a volume resistivity of 10 formed by attaching a conductive metal oxide to the surface of a core made of an insulating material. ^-3 to 10 ⁷ [Ωcm], composite fine particles having an average particle diameter of 50 to 300 nm, and a charge transporting compound are contained in the cured resin.
In the photoreceptor of the present invention, since the main component of the surface layer is a cured resin, basically a high film strength can be obtained, and thus a high durability can be obtained. In addition, the composite fine particles having an average particle diameter of 50 to 300 nm are contained in the surface layer, so that the surface of the photoreceptor can be appropriately roughened, so that good cleaning properties can be obtained. Even if the composite fine particles have a low volume resistivity, the electric resistance in the surface layer can be kept moderate by containing the charge transporting compound in the surface layer, and the image flow is generated. Can be suppressed. Further, since the average particle diameter of the composite fine particles is relatively large, as shown in FIG. 1, the number of conductive paths between the composite fine particles 101 in the layer thickness direction of the surface layer 100 is smaller than that when the average particle diameter is small. As a result, the number of times of passing through the resin portion having a higher electrical resistance than in the composite fine particles is reduced, and the charge transfer in the surface layer is not hindered, and the potential in the exposed portion can be stably maintained.

(Cured resin)
The cured resin is a main component constituting the surface layer. This cured resin is obtained by polymerizing a compound having two or more radical polymerizable functional groups (hereinafter also referred to as “polyfunctional radical polymerizable compound”). Specifically, the curable resin is formed by polymerizing and curing a polyfunctional radical polymerizable compound by irradiation with active rays such as ultraviolet rays and electron beams.

As the monomer for forming the curable resin, a polyfunctional radical polymerizable compound is used, but a compound having one radical polymerizable functional group (hereinafter also referred to as “monofunctional radical polymerizable compound”) is used in combination. You can also. In the case of using a monofunctional radically polymerizable compound, the ratio is preferably 10 to 50% by mass with respect to the total amount of monomers for forming the cured resin.
Examples of the radical polymerizable functional group include a vinyl group, an acryloyl group, and a methacryloyl group.

Since the polyfunctional radical polymerizable compound can be cured in a small amount of light or in a short time, an acryloyl group (CH ₂ ═CHCO—) or a methacryloyl group (CH ₂ ═CCH ₃ CO—) is used as the radical polymerizable functional group. (Meth) acrylic monomers having 2 or more) or oligomers thereof are particularly preferred.

  In the present invention, the polyfunctional radically polymerizable compound may be used alone or in combination. In addition, these polyfunctional radical polymerizable compounds may use monomers, but may be used after oligomerization.

  Hereinafter, specific examples of the polyfunctional radically polymerizable compound are shown.

However, in the chemical formulas showing the exemplary compounds (M1) to (M14), R represents an acryloyl group (CH ₂ ═CHCO—) and R ′ represents a methacryloyl group (CH ₂ ═CCH ₃ CO—).

(Composite fine particles)
The composite fine particles have a volume resistivity of 10 ⁻³ to 10 ⁷ [Ωcm] and an average particle diameter of 50 to 300 nm, which is formed by attaching a conductive metal oxide to the surface of a core material made of an insulating material. Is. The composite fine particles have a core-shell structure in which a part or all of the surface of the core material is coated with a conductive metal oxide as a coating material.

The volume resistivity of the composite fine particles is 10 ⁻³ to 10 ⁷ [Ωcm], and preferably 10 ⁻¹ to 10 ³ [Ωcm].
The volume resistivity of the composite fine particles is a value measured with a TR8611A digital super insulation resistance / microammeter manufactured by Takeda Riken Co., Ltd. in an environment of a temperature of 23 ° C. and a humidity of 50%.

The average particle size of the composite fine particles is 50 to 300 nm, preferably 80 to 200 nm, as the number average primary particle size.
When the average particle diameter of the composite fine particles is within the above range, the surface of the photoreceptor can be appropriately roughened, and the cleaning property is improved. In addition, since the particle size is relatively large, the number of conductive paths between fine particles in the layer thickness direction of the surface layer is smaller than when the average particle size is small, and the potential characteristics in the surface layer are stably maintained. be able to.

In the present invention, the average particle size of the composite fine particles is measured as follows.
The average particle size of the composite fine particles is calculated from a photograph image obtained by observing and photographing the composite fine particles with a transmission electron microscope. The magnification of the microscope is set to 10,000 times, and the photograph is taken at random from the photograph image. And 100 particles are extracted and calculated. Specifically, the horizontal ferret diameter of 100 fine particles is measured by image analysis processing, an average value is calculated, and this is used as the number average primary particle diameter. Note that the image analysis processing can be automatically performed by, for example, driving a program built in the transmission electron microscope measurement apparatus. In the present invention, a transmission electron microscope “JEM-2000FX” (manufactured by JEOL Ltd.) was used to measure the particle size of the fine particles.

The number density of the composite fine particles per unit volume of the surface layer is preferably 1 to 550 [number / μm ³ ], more preferably 5 to 200 [number / μm ³ ], and particularly preferably 10 to 100. [Pieces / μm ³ ].
When the number density of the composite fine particles is within the above range, the surface of the photoreceptor can be appropriately roughened and the cleaning property is improved. In addition, if the number density is within the above range in relation to the average particle diameter of the composite fine particles, the composite fine particles will be contained in a densely packed state in the surface layer, as shown in FIG. The number of conductive paths between the composite fine particles 101 in the layer thickness direction of the surface layer 100 can be further reduced, and the potential characteristics of the surface layer can be stably maintained.

In the present invention, the number density n of the composite fine particles is the number per 1 μm ^{3 in the} surface layer represented by n = W ₂ / W ₁ . Here, W ₁ is the weight per composite fine particle, and W ₁ is represented by W ₁ = density ρ / volume V per composite fine particle. Here, ρ is 5.7 (g / cm ³ ), V (cm ³ ) is (4πr ³ ) / 3, and r (cm) is the radius of the composite fine particles. W ₂ is the weight of the composite fine particles contained per 1 μm ³ in the surface layer, and W ₂ is the amount of monomer charged per W ₂ = 1 μm ³ × {composite fine particle parts / (monomer mass part + composite fine particles) Mass parts)}.

The composite fine particles are preferably contained in a proportion of 50 to 250 parts by mass with respect to 100 parts by mass of the cured resin, more preferably 70 to 200 parts by mass, and particularly preferably 80 to 150 parts by mass.
When the content ratio of the composite fine particles is within the above range, basically high potential characteristics can be secured. In particular, when the content ratio of the composite fine particles is 80 to 150 parts by mass, the surface of the photoreceptor can be appropriately roughened and the cleaning property is improved.

The core material constituting the composite fine particles is made of an insulating material, and the volume resistivity is particularly preferably 10 ¹⁰ to 10 ¹⁶ [Ωcm]. The core material is preferably at least one selected from, for example, barium sulfate, alumina, and silica. Particularly, barium sulfate is preferable in terms of ensuring the transparency of the surface layer.

The conductive metal oxide constituting the composite fine particles preferably has a volume resistivity of 10 ⁻³ to 10 ⁷ [Ωcm]. The conductive metal oxide is preferably at least one selected from, for example, tin oxide, titanium oxide, zinc oxide, zirconia, and indium tin oxide.

The adhesion amount of the conductive metal oxide to the core material is preferably 30 to 70% by mass, and more preferably 40 to 60% by mass.
When the amount of the conductive metal oxide deposited is within the above range, high potential characteristics can be ensured.

  As a method for adhering the conductive metal oxide, which is a coating material, to the core material, for example, a method disclosed in Japanese Patent Application Laid-Open No. 2009-255042 can be employed.

It is preferable that the composite fine particles are surface-treated with a surface treatment agent made of a compound having a radical polymerizable functional group.
Specifically, the radically polymerizable functional group was introduced to the surface of the composite fine particle by subjecting the conductive metal oxide constituting the composite fine particle to a surface treatment with a surface treatment agent comprising a compound having a radical polymerizable functional group. Preferably.
Since the composite fine particles are surface-treated with a surface treatment agent comprising a compound having a radical polymerizable functional group, in the step of forming a surface layer in the photoreceptor production process described later, a polyfunctional radical polymerizable compound and A cross-linked structure can be formed by reaction, the film strength of the surface layer can be sufficiently obtained, the potential stability can be obtained, and both high durability and potential characteristics can be achieved. Moreover, high dispersibility is obtained for the metal oxide fine particles in the cured resin.

  Examples of the radical polymerizable functional group in the surface treatment agent include a vinyl group, an acryloyl group, and a methacryloyl group. Such a radical polymerizable functional group can react with a polyfunctional radical polymerizable compound forming a cured resin to form a firm surface layer. As the surface treatment agent comprising a compound having a radical polymerizable functional group, a silane coupling agent having a polymerizable functional group such as a vinyl group, an acryloyl group, or a methacryloyl group is preferable.

  Hereinafter, a surface treatment agent having an acryloyl group or a methacryloyl group is shown as a specific example of the surface treatment agent comprising a compound having a radical polymerizable functional group.

_{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

  Moreover, as a surface treating agent, you may use the silane compound which has a reactive organic group in which radical polymerization is possible other than what is shown to the said exemplary compound (S-1)-(S-36).

  The surface treatment agents may be used alone or in combination of two or more.

  It is preferable that the processing amount of a surface treating agent is 0.1-200 mass parts with respect to 100 mass parts of composite microparticles, More preferably, it is 7-70 mass parts.

  Examples of the treatment method for the composite fine particles of the surface treatment agent include a method of wet crushing a slurry (suspension of solid particles) containing the composite fine particles and the surface treatment agent. By this method, re-aggregation of the composite fine particles is prevented and at the same time the surface treatment of the composite fine particles proceeds. Thereafter, the solvent is removed to form powder.

  Examples of the surface treatment apparatus include a wet media dispersion type apparatus. In this wet media dispersion type device, a process of crushing and pulverizing and dispersing the agglomerated particles of the composite fine particles by filling beads in the container as media and rotating the stirring disk mounted perpendicular to the rotation axis at high speed. The apparatus is not limited as long as the composite fine particles are sufficiently dispersed and can be surface-treated when the surface treatment is performed on the composite fine particles. For example, vertical, horizontal, continuous, batch Various forms such as a formula can be adopted. Specifically, a sand mill, ultra visco mill, pearl mill, glen mill, dyno mill, agitator mill, dynamic mill and the like can be used. These dispersion-type devices are finely pulverized and dispersed by impact crushing, friction, shearing, shear stress, etc., using a grinding medium (media) such as balls and beads.

  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 those made of zirconia or zircon are particularly preferable. Further, as the size of the beads, those having a diameter of about 1 to 2 mm are usually used, but in the present invention, those having a diameter of about 0.1 to 1.0 mm are preferably used.

  Various materials such as stainless steel, nylon and ceramic can be used for the disk and container inner wall used in the wet media dispersion type apparatus. In the present invention, the disk and container inner wall made of ceramic such as zirconia or silicon carbide are particularly used. Is preferred.

(Charge transporting compound)
The charge transporting compound is not particularly limited as long as it has a charge transporting property of transporting charge carriers in the surface layer, but it is particularly preferable that the compound be represented by the general formula (1).
In the photoconductor of the present invention, since the charge transporting compound is contained in the surface layer, the charge transporting compound has a higher electric resistance than the composite fine particles, so that the electric resistance in the surface layer is appropriately maintained. Therefore, it is possible to suppress the occurrence of image flow. If a compound having no charge transporting property is added, the electric resistance in the surface layer becomes too high, and the function as a photoreceptor cannot be expressed.
The charge transporting compound used in the present invention is not reactive with the composite fine particles surface-treated with a surface treatment agent comprising a polyfunctional radical polymerizable compound or a compound having a radical polymerizable functional group. is there.

In the general formula (1), R ¹ and R ² are each independently a hydrogen atom or a methyl group, preferably a methyl group. R ³ is a linear or branched alkyl group having 1 to 5 carbon atoms, preferably 2 to 4 carbon atoms.

  Specific examples of the compound represented by the general formula (1) are shown below.

  The compound represented by the general formula (1) can be synthesized by a known synthesis method, for example, a method disclosed in JP-A-2006-143720.

The charge transporting compound is preferably contained in a proportion of 10 to 30 parts by mass, more preferably 15 to 25 parts by mass with respect to 100 parts by mass of the cured resin.
When the content ratio of the charge transporting compound is within the above range, the occurrence of image drift can be reliably suppressed. In particular, when the content ratio of the composite fine particles is in the range of 80 to 150 parts by mass, the content ratio of the charge transporting compound is 15 to 25 parts by mass. Both can be achieved.
When the content ratio of the charge transporting compound is excessive, the film strength of the surface layer may be reduced. On the other hand, when the content ratio of the charge transporting compound is too small, there is a possibility that image flow may occur.

  The surface layer according to the present invention may contain other components in addition to the cured resin, the composite fine particles and the charge transporting compound. For example, various antioxidants and various kinds of fluorine atom-containing resin particles, for example. The lubricant particles can also be added. Examples of the fluorine atom-containing resin particles include tetrafluoroethylene resin, trifluorinated ethylene chloride resin, hexafluoroethylene chloride propylene resin, vinyl fluoride resin, vinylidene fluoride resin, ethylene difluoride dichloride resin, and these One or two or more types are preferably selected from the copolymers, but tetrafluoroethylene resin and vinylidene fluoride resin are particularly preferable.

  The layer thickness of the surface layer is preferably 0.2 to 10 μm, more preferably 0.5 to 6 μm.

  Hereinafter, the configuration of the photoconductor other than the surface layer will be described in the case of the layer configuration (1).

[Conductive support]
The conductive support constituting the photoreceptor of the present invention may be any conductive support, for example, a metal such as aluminum, copper, chromium, nickel, zinc and stainless steel formed into a drum or sheet, A metal foil such as aluminum or copper laminated on a plastic film, a metal film deposited with aluminum, indium oxide, tin oxide or the like on a plastic film, a metal provided with a conductive layer by applying a conductive substance alone or with a binder resin, Examples include plastic film and paper.

[Middle layer]
In the photoreceptor of the present invention, an intermediate layer having a barrier function and an adhesive function can be provided between the conductive support and the photosensitive layer. In consideration of various failure prevention, it is preferable to provide an intermediate layer.

  Such an intermediate layer contains, for example, a binder resin (hereinafter also referred to as “binder resin for intermediate layer”) and, if necessary, conductive particles and metal oxide particles.

  Examples of the intermediate layer binder resin include casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyamide resin, polyurethane resin, and gelatin. Among these, alcohol-soluble polyamide resins are preferable.

The intermediate layer can contain various conductive particles and metal oxide particles for the purpose of adjusting the resistance. For example, various metal oxide particles such as alumina, zinc oxide, titanium oxide, tin oxide, antimony oxide, indium oxide, and bismuth oxide can be used. Ultrafine particles such as indium oxide doped with tin, tin oxide doped with antimony, and zirconium oxide can be used.
The number primary average particle diameter of such metal oxide particles is preferably 0.3 μm or less, more preferably 0.1 μm or less.

  These metal oxide particles may be used alone or in combination of two or more. When two or more kinds are mixed, it may take the form of a solid solution or fusion.

  The content ratio of the conductive particles or the metal oxide particles is preferably 20 to 400 parts by mass, more preferably 50 to 350 parts by mass with respect to 100 parts by mass of the binder resin.

  The thickness of the intermediate layer is preferably 0.1 to 15 μm, more preferably 0.3 to 10 μm.

(Charge generation layer)
The charge generation layer in the photosensitive layer constituting the photoreceptor of the present invention contains a charge generation material and a binder resin (hereinafter also referred to as “binder resin for charge generation layer”).

  Examples of charge generation materials include azo raw materials such as Sudan Red and Diane Blue, quinone pigments such as pyrenequinone and anthanthrone, quinocyanine pigments, perylene pigments, indigo pigments such as indigo and thioindigo, pyranthrone and diphthaloylpyrene. Examples thereof include, but are not limited to, ring quinone pigments and phthalocyanine pigments. Among these, polycyclic quinone pigments and titanyl phthalocyanine pigments are preferable. These charge generation materials may be used alone or in combination of two or more.

  As the binder resin for the charge generation layer, 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 resins, phenol resins, polyester resins, alkyd resins, polycarbonate resins, silicone resins, melamine resins, and copolymer resins containing two or more of these resins (eg, vinyl chloride-vinyl acetate copolymer resins, chlorides) Vinyl-vinyl acetate-maleic anhydride copolymer resin), poly-vinylcarbazole resin, and the like, but are not limited thereto. Among these, polyvinyl butyral resin is preferable.

  The content ratio of the charge generation material in the charge generation layer is preferably 1 to 600 parts by mass, more preferably 50 to 500 parts by mass with respect to 100 parts by mass of the binder resin for charge generation layer.

  The layer thickness of the charge generation layer varies depending on the characteristics of the charge generation material, the characteristics of the binder resin for the charge generation layer, the content ratio, etc., but is preferably 0.01 to 5 μm, more preferably 0.05 to 3 μm. is there.

(Charge transport layer)
The charge transport layer in the photosensitive layer constituting the photoreceptor of the present invention contains a charge transport material and a binder resin (hereinafter also referred to as “binder resin for charge transport layer”).

  Examples of the charge transport material for the charge transport layer include a charge transport material such as a triphenylamine derivative, a hydrazone compound, a styryl compound, a benzidine compound, and a butadiene compound.

  A known resin can be used as the binder resin for the charge transport layer. Polycarbonate resin, polyacrylate resin, polyester resin, polystyrene resin, styrene-acrylonitrile copolymer resin, polymethacrylic ester resin, styrene-methacrylic ester Examples of the resin include a copolymer resin, and a polycarbonate resin is preferable. Furthermore, BPA (bisphenol A) type, BPZ (bisphenol Z) type, dimethyl BPA type, BPA-dimethyl BPA copolymer type polycarbonate resin and the like are preferable in terms of crack resistance, wear resistance, and charging characteristics.

  The content ratio of the charge transport material in the charge transport layer is preferably 10 to 500 parts by weight, more preferably 20 to 250 parts by weight with respect to 100 parts by weight of the charge transport layer binder resin.

  The layer thickness of the charge transport layer varies depending on the characteristics of the charge transport material, the characteristics and the content ratio of the binder resin for the charge transport layer, but is preferably 5 to 40 μm, more preferably 10 to 30 μm.

  In the charge transport layer, an antioxidant, an electronic conductive agent, a stabilizer, silicone oil, or the like may be added. As the antioxidant, those disclosed in JP-A No. 2000-305291 and as the electronic conductive agent are disclosed in JP-A Nos. 50-137543 and 58-76483.

[Method for producing photoreceptor]
As a manufacturing method of the photoreceptor of the present invention, for example, it can be manufactured through the following steps.
Process (1): The process of forming an intermediate | middle layer by apply | coating the coating liquid for intermediate | middle layer formation to the outer peripheral surface of an electroconductive support body, and drying.
Step (2): A step of forming a charge generation layer by applying a coating solution for forming a charge generation layer on the outer peripheral surface of an intermediate layer formed on a conductive support and drying it.
Step (3): A step of forming a charge transport layer by applying a coating liquid for forming a charge transport layer to the outer peripheral surface of the charge generation layer formed on the intermediate layer and drying.
Step (4): The surface layer is formed by applying a coating solution for forming a surface layer on the outer peripheral surface of the charge transport layer formed on the charge generation layer to form a coating film, and curing the coating film. Forming.

[Step (1): Formation of intermediate layer]
The intermediate layer is prepared by dissolving the binder resin for the intermediate layer in a solvent to prepare a coating liquid (hereinafter also referred to as “intermediate layer forming coating liquid”), and if necessary, conductive particles and metal oxide particles. After the dispersion, the coating solution can be formed on the conductive support in a certain film thickness to form a coating film, and the coating film can be dried.

As a means for dispersing the conductive particles and metal oxide particles in the coating solution for forming the intermediate layer, an ultrasonic disperser, a ball mill, a sand mill, a homomixer, or the like can be used, but it is not limited to these. Absent.
Examples of the coating method for the intermediate layer forming coating solution include known dip coating methods, spray coating methods, spinner coating methods, bead coating methods, blade coating methods, beam coating methods, slide hopper methods, circular slide hopper methods, and the like. A method is mentioned.
The method for drying the coating film can be appropriately selected according to the type of solvent and the film thickness, but thermal drying is preferred.

  The solvent used in the intermediate layer forming step is not particularly limited as long as the conductive particles and the metal oxide particles are well dispersed and the binder resin for the intermediate layer is dissolved. Specifically, alcohols having 1 to 4 carbon atoms such as methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol, t-butanol, sec-butanol are excellent in binder resin solubility and coating performance. preferable. In addition, examples of co-solvents that can be used in combination with the above-described solvent to improve storage stability and particle dispersibility and obtain a preferable effect include benzyl alcohol, toluene, methylene chloride, cyclohexanone, and tetrahydrofuran.

  The concentration of the binder resin for the intermediate layer in the coating liquid for forming the intermediate layer is appropriately selected according to the thickness of the intermediate layer and the production rate.

[Step (2): Formation of Charge Generation Layer]
The charge generation layer is prepared by dispersing a charge generation material in a solution in which a charge generation layer binder resin is dissolved in a solvent to prepare a coating solution (hereinafter also referred to as “charge generation layer forming coating solution”). The coating solution can be formed on the intermediate layer by coating the intermediate layer with a certain film thickness to form a coating film and then drying the coating film.

As a means for dispersing the charge generation material in the charge generation layer forming coating solution, for example, an ultrasonic disperser, a ball mill, a sand mill, a homomixer or the like can be used, but is not limited thereto.
As a coating method for the charge generation layer forming coating solution, for example, dip coating method, spray coating method, spinner coating method, bead coating method, blade coating method, beam coating method, slide hopper method, circular slide hopper method and the like are known. The method is mentioned.
The method for drying the coating film can be appropriately selected according to the type of solvent and the film thickness, but thermal drying is preferred.

  Examples of the solvent used for forming the charge generation layer include toluene, xylene, methylene chloride, 1,2-dichloroethane, methyl ethyl ketone, cyclohexane, ethyl acetate, t-butyl acetate, methanol, ethanol, propanol, butanol, methyl cellosolve, Examples include, but are not limited to, 4-methoxy-4-methyl-2-pentanone, ethyl cellosolve, tetrahydrofuran, 1-dioxane, 1,3-dioxolane, pyridine, and diethylamine.

[Step (3): Formation of Charge Transport Layer]
The charge transport layer is prepared by preparing a coating liquid in which a binder resin for a charge transport layer and a charge transport material are dissolved in a solvent (hereinafter, also referred to as “coating liquid for forming a charge transport layer”). It can form by apply | coating to a fixed film thickness on a layer, forming a coating film, and drying the said coating film.

As a coating method of the coating solution for forming the charge transport layer, for example, dip coating method, spray coating method, spinner coating method, bead coating method, blade coating method, beam coating method, slide hopper method, circular slide hopper method and the like are known. The method is mentioned.
The method for drying the coating film can be appropriately selected according to the type of solvent and the film thickness, but thermal drying is preferred.

  Examples of the solvent used for forming the charge transport layer include toluene, xylene, methylene chloride, 1,2-dichloroethane, methyl ethyl ketone, cyclohexanone, ethyl acetate, butyl acetate, methanol, ethanol, propanol, butanol, tetrahydrofuran, and 1,4. -Dioxane, 1,3-dioxolane, pyridine, diethylamine and the like are exemplified, but not limited thereto.

[Step (4): Formation of surface layer]
The surface layer is formed by adding a polyfunctional radical polymerizable compound, composite fine particles, a charge transporting compound, a polymerization initiator, and other components as required to a known solvent to a coating solution (hereinafter, “surface layer forming coating solution”). Is also applied to the outer peripheral surface of the charge transport layer formed in the step (3) to form a coating film, the coating film is dried, A surface layer can be formed by irradiating an active ray such as an electron beam to cause the radical polymerizable compound component in the coating film to undergo a polymerization reaction and cure.

  When the surface layer is subjected to a surface treatment with a reaction between polyfunctional radical polymerizable compounds or a composite fine particle having a compound having a radical polymerizable functional group in the course of coating, drying and curing. Is formed as a cross-linked curable resin by the reaction of the surface treatment agent with the polyfunctional radical polymerizable compound.

  In the coating solution for forming the surface layer, the composite fine particles are in a ratio of 50 to 250 parts by mass with respect to 100 parts by mass of all monomers (polyfunctional radical polymerizable compound or monofunctional radical polymerizable compound) for forming the cured resin. It is preferably contained, more preferably 70 to 200 parts by mass, and particularly preferably 80 to 150 parts by mass. The charge transporting compound should be contained in a proportion of 10 to 30 parts by mass with respect to 100 parts by mass of all monomers (polyfunctional radical polymerizable compound or monofunctional radical polymerizable compound) for forming the cured resin. Is more preferable, and 15 to 25 parts by mass is more preferable.

  As a means for dispersing the composite fine particles in the surface layer forming coating solution, an ultrasonic disperser, a ball mill, a sand mill, a homomixer, or the like can be used, but is not limited thereto.

  As the solvent used for forming the surface layer, any solvent can be used as long as it can dissolve or disperse the polyfunctional radical polymerizable compound, the composite fine particles and the charge transporting compound. For example, methanol, ethanol, n-propyl alcohol , Isopropyl alcohol, n-butanol, t-butanol, sec-butanol, benzyl alcohol, toluene, xylene, methylene chloride, methyl ethyl ketone, cyclohexane, ethyl acetate, butyl acetate, methyl cellosolve, ethyl cellosolve, tetrahydrofuran, 1-dioxane, 1, Examples include, but are not limited to, 3-dioxolane, pyridine, and diethylamine.

  As a coating method of the surface layer forming coating solution, for example, known methods such as dip coating method, spray coating method, spinner coating method, bead coating method, blade coating method, beam coating method, slide hopper method, circular slide hopper method, etc. A method is mentioned.

The coating solution for forming the surface layer is preferably applied using a circular slide hopper coating device.
Hereinafter, a method for applying the surface layer forming coating solution using the circular slide hopper coating apparatus will be described in detail.

  As shown in FIGS. 2 and 3, the circular slide hopper coating apparatus includes a cylindrical base 251, an annular coating head 260 provided so as to surround the periphery thereof, and a storage tank 254 for storing the coating liquid L. It consists of.

  The base material 251 here is a base material to which the surface layer forming coating solution is to be applied, for example, a state in which an intermediate layer and a photosensitive layer are formed on a conductive support (a surface layer is formed). Not).

The coating head 260 has a narrow coating liquid distribution slit 262 having a coating liquid outlet 261 that opens to the base 251 side along the entire direction of the annular coating head 260 along the direction perpendicular to the longitudinal direction of the base 251. Is formed over. The coating liquid distribution slit 262 communicates with the annular coating liquid distribution chamber 263, and the coating liquid distribution chamber 263 is supplied with the coating liquid L in the storage tank 254 through the supply pipe 264 by the pumping pump 255. Is formed.
On the lower side of the coating liquid outlet 261 of the coating liquid distribution slit 262, there is formed a slide surface 265 that is continuously inclined downward and is formed with a dimension slightly larger than the outer dimension of the substrate 251. Furthermore, a lip portion (bead; liquid reservoir portion) 266 extending downward from the end of the slide surface 265 is formed.

  In such a circular slide hopper coating apparatus, when the coating liquid L is pushed out from the coating liquid distribution slit 262 and allowed to flow down along the slide surface 265 in the process of moving the base 251 in the direction of the arrow, the slide surface 265 ends. The resulting coating liquid L forms a bead between the end of the slide surface 265 and the outer peripheral surface of the substrate 251, and is then applied to the surface of the substrate 251 to form a coating film F. Is discharged from the discharge port 267.

  In such a coating method using a circular slide hopper coating apparatus, the slide surface end and the base material are arranged with a certain gap (about 2 μm to 2 mm), so that the base material is not damaged and the layers have different properties. Even in the case of forming a multilayer, it can be applied without damaging the already applied layer. Furthermore, when multiple layers with different properties and dissolved in the same solvent are formed, the time in the solvent is much shorter compared to the dip coating method, so that the lower layer component hardly elutes to the upper layer side, so Can also be applied without degrading the dispersibility of the composite barium sulfate fine particles.

  The coating film may be cured without being dried, but it is preferable to perform the curing treatment after natural drying or heat drying.

  Drying conditions can be appropriately selected depending on the type of solvent, film thickness, and the like. The drying temperature is preferably room temperature to 180 ° C, particularly preferably 80 to 140 ° C. The drying time is preferably 1 minute to 200 minutes, and particularly preferably 5 minutes to 100 minutes.

  Examples of the method of reacting the radical polymerizable compound include a method of reacting by electron beam cleavage and a method of reacting with light and heat by adding a radical polymerization initiator. As the radical polymerization initiator, either a photopolymerization initiator or a thermal polymerization initiator can be used. A photopolymerization initiator and a thermal polymerization initiator can also be used in combination.

  As the radical polymerization initiator, a photopolymerization initiator is preferable, and among them, an alkylphenone compound or a phosphine oxide compound is preferable. In particular, a compound having an α-hydroxyacetophenone structure or an acylphosphine oxide structure is preferable.

  Hereinafter, specific examples of acylphosphine oxide compounds as photopolymerization initiators are shown.

  The polymerization initiators may be used alone or in combination of two or more.

  It is preferable that the addition ratio of a polymerization initiator is 0.1-20 mass parts with respect to 100 mass parts of radically polymerizable compounds, More preferably, it is 0.5-10 mass parts.

  As the curing treatment, the coating film is irradiated with actinic radiation, polymerized by generating radicals, and cured by forming a cross-linking bond by a cross-linking reaction between molecules and within the molecule, thereby producing a cured resin. As the actinic radiation, ultraviolet rays and electron beams are more preferred, and ultraviolet rays are particularly preferred because they are easy to 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 the like can be used.
Irradiation conditions vary depending on each lamp, but the irradiation amount of active rays is usually 5 to 500 mJ / cm ² , preferably 5 to 100 mJ / cm ² .
The power of the lamp is preferably 0.1 kW to 5 kW, particularly preferably 0.5 kW to 3 kW.

  As an electron beam source, there is no particular limitation on the electron beam irradiation apparatus, and generally, an electron beam accelerator for electron beam irradiation is a curtain beam type that is relatively inexpensive and can provide a large output. Used. The acceleration voltage during electron beam irradiation is preferably 100 to 300 kV. The absorbed dose is preferably 0.5 to 10 Mrad.

  The irradiation time for obtaining the necessary amount of active ray irradiation is preferably 0.1 second to 10 minutes, and more preferably 0.1 second to 5 minutes from the viewpoint of work efficiency.

  In the step of forming the surface layer, drying can be performed before and after irradiation with active rays and during irradiation with active rays, and the timing of drying can be appropriately selected by combining these.

According to the above photoreceptor, a conductive metal oxide having a volume resistivity of 10 ⁻³ to 10 ⁷ [Ωcm] is adhered to the surface of the core material made of an insulating material in the cured resin. The composite fine particles having a specific average particle diameter and the charge transporting compound are contained, so that it has high durability and ensures good cleaning properties while maintaining image cleanliness. Occurrence is suppressed.
Specifically, when the main component of the surface layer is a cured resin, basically a high film strength can be obtained, and thus high durability can be obtained. Since the composite fine particles having an average particle diameter of 50 to 300 nm are contained, the surface of the photoreceptor can be appropriately roughened, so that good cleaning properties can be obtained, and the composite fine particles have a volume resistivity. Even if it is low, by containing the charge transporting compound in the surface layer, the electrical resistance in the surface layer can be kept moderate, and the occurrence of image flow can be suppressed. In addition, since the average particle size of the composite fine particles is relatively large, the number of conductive paths between the fine particles in the layer thickness direction of the surface layer is smaller than that in the case where the average particle size is small, and as a result, the electrical path is smaller than in the composite fine particles. The number of times of passing through the resin portion having high resistance is reduced, charge transfer in the surface layer is not hindered, and the potential in the exposed portion can be stably maintained.

[Image forming apparatus]
The image forming apparatus of the present invention includes a photosensitive member, a charging unit for charging the surface of the photosensitive member, an exposure unit for forming an electrostatic latent image on the surface of the photosensitive member, and developing the electrostatic latent image with toner. A developing unit that forms a toner image; a transfer unit that transfers the toner image to a transfer material; a fixing unit that fixes the toner image transferred to the transfer material; and a cleaning unit that removes residual toner on the photoreceptor. The photoconductor of the present invention is used as the photoconductor. Further, it is preferable to use a blade that scratches the surface of the photoconductor, the tip of which is provided in contact with the photoconductor as the cleaning means.

FIG. 4 is a cross-sectional view illustrating the configuration of an example of the image forming apparatus of the present invention.
This image forming apparatus is called a tandem color image forming apparatus, and includes four sets of image forming units (image forming units) 10Y, 10M, 10C, and 10Bk, an endless belt-shaped intermediate transfer body unit 7, and paper feeding Means 21 and fixing means 24. A document image reading device SC is disposed on the upper part of the main body A of the image forming apparatus.

  The image forming unit 10Y for forming a yellow image includes a charging unit 2Y, an exposure unit 3Y, a developing unit 4Y, a primary transfer roller 5Y as a primary transfer unit, and a cleaning unit 6Y arranged around the drum-shaped photoreceptor 1Y. Have The image forming unit 10M that forms a magenta image includes a drum-shaped photoreceptor 1M, a charging unit 2M, an exposure unit 3M, a developing unit 4M, a primary transfer roller 5M as a primary transfer unit, and a cleaning unit 6M. The image forming unit 10C that forms a cyan image includes a drum-shaped photoreceptor 1C, a charging unit 2C, an exposure unit 3C, a developing unit 4C, a primary transfer roller 5C as a primary transfer unit, and a cleaning unit 6C. The image forming unit 10Bk for forming a black image includes a drum-shaped photoreceptor 1Bk, a charging unit 2Bk, an exposure unit 3Bk, a developing unit 4Bk, a primary transfer roller 5Bk as a primary transfer unit, and a cleaning unit 6Bk. The image forming apparatus of the present invention uses the above-described photoreceptor of the present invention as the photoreceptors 1Y, 1M, 1C, and 1Bk.

  The four sets of image forming units 10Y, 10M, 10C, and 10Bk are centered on the photoreceptors 1Y, 1M, 1C, and 1Bk, and charging units 2Y, 2M, 2C, and 2Bk, and exposure units 3Y, 3M, 3C, and 3Bk. , Rotating developing means 4Y, 4M, 4C and 4Bk, and cleaning means 6Y, 6M, 6C and 6Bk for cleaning the photoreceptors 1Y, 1M, 1C and 1Bk.

  The image forming units 10Y, 10M, 10C, and 10Bk have the same configuration except that the colors of toner images formed on the photoreceptors 1Y, 1M, 1C, and 1Bk are different, and the image forming unit 10Y is taken as an example in detail. explain.

  In the image forming unit 10Y, a charging unit 2Y, an exposure unit 3Y, a developing unit 4Y, and a cleaning unit 6Y are arranged around a photoconductor 1Y that is an image forming body, and a yellow (Y) toner image is placed on the photoconductor 1Y. To form. In the present embodiment, in the image forming unit 10Y, at least the photosensitive member 1Y, the charging unit 2Y, the developing unit 4Y, and the cleaning unit 6Y are provided so as to be integrated.

  The charging unit 2Y is a unit that applies a uniform potential to the photoreceptor 1Y. In this embodiment, a corona discharge type charger is used for the photoreceptor 1Y.

  The exposure unit 3Y is a unit that performs exposure based on an image signal (yellow) on the photoreceptor 1Y to which a uniform potential is applied by the charging unit 2Y, and forms an electrostatic latent image corresponding to a yellow image. As the exposure means 3Y, a device composed of an LED having light emitting elements arranged in an array in the axial direction of the photoreceptor 1Y and an imaging element, a laser optical system, or the like is used.

  The developing means 4Y includes, for example, a developing sleeve that contains a magnet and rotates while holding the developer, and a voltage applying device that applies a DC and / or AC bias voltage between the photosensitive member and the developing sleeve.

  The fixing unit 24 is, for example, a heat roller fixing configured by a heating roller having a heating source therein and a pressure roller provided in pressure contact with the heating roller so as to form a fixing nip portion. One of the methods is mentioned.

  The cleaning unit 6Y includes a cleaning blade and a brush roller provided on the upstream side of the cleaning blade.

  Specifically, as shown in FIG. 5, the cleaning unit 6 includes a cleaning blade 66 </ b> A provided so that the tip abuts on the surface of the photoconductor 1, and the surface of the photoconductor 1 provided upstream of the cleaning blade. And a brush roller 66C in contact with.

  The cleaning blade 66 </ b> A has a function of removing the residual toner attached to the photoconductor 1 and a function of rubbing the surface of the photoconductor 1.

  The cleaning blade 66A is supported by a support member 66B. A rubber elastic body is used as the material of the cleaning blade 66A, and urethane rubber, silicon rubber, fluorine rubber, chloropyrene rubber, butadiene rubber, and the like are known as the material. Among these, urethane rubber is other materials. It is particularly preferable in that it has excellent wear characteristics compared to other rubbers.

  The support member 66B is configured by a plate-like metal member or a plastic member. Examples of the metal member include a stainless steel plate, an aluminum plate, and a vibration control steel plate.

  In the present invention, it is preferable that the tip of the cleaning blade 66 </ b> A that contacts the surface of the photoconductor 1 abuts in a state where a load is applied in a direction opposite to the rotation direction of the photoconductor 1 (counter direction). As shown in FIG. 5, it is preferable that the tip of the cleaning blade 66 </ b> A forms a contact surface when it comes into contact with the photoreceptor 1.

  Preferable values of the contact load P and contact angle θ of the cleaning blade 66A to the photosensitive member 1 are P = 5 to 40 N / m and θ = 5 to 35 °.

The contact load P is a normal vector value of the contact force P ′ when the cleaning blade 66A is brought into contact with the drum-shaped photoreceptor 1.
Further, the contact angle θ represents an angle formed between the tangent line X at the contact point A of the photoreceptor 1 and the blade before deformation.

  66E is a rotation shaft that enables the support member 66B to rotate, and 66G is a load spring.

The free length L is preferably 6 to 15 mm.
As shown in FIG. 5, the free length L of the cleaning blade 66A refers to the length of the tip of the cleaning blade 66A before deformation from the position of the end B of the support member 66B.

The thickness t of the cleaning blade 66A is preferably 0.5 to 10 mm.
Here, the thickness t of the cleaning blade 66A refers to the length in the direction perpendicular to the bonding surface of the support member 66B, as shown in FIG.

  The brush roller 66C has a function of rubbing the surface of the photoconductor 1 together with a function of removing the residual toner attached to the photoconductor 1 and a function of collecting the residual toner removed by the cleaning blade 66A. That is, the brush roller 66C comes into contact with the surface of the photosensitive member 1, and the traveling direction of the brush roller 66C rotates in the same direction as that of the photosensitive member 1, thereby removing residual toner and paper dust on the photosensitive member 1 and cleaning. The residual toner removed by the blade 66A is transported and collected by the transport screw 66J. Then, the surface of the photoreceptor 1 is scraped and refreshed.

  It is preferable to remove a removed matter such as residual toner transferred from the photosensitive member 1 to the brush roller 66C by bringing a flicker 66I as a removing unit into contact with the brush roller 66C. Further, the toner adhering to the flicker 66I is removed by the scraper 66D, and the toner is collected by the conveying screw 66J. The collected toner is taken out to the outside as waste, or is transported to the developing means via a recycling pipe (not shown) for toner recycling and reused.

As the flicker 66I, a metal tube such as stainless steel or aluminum is preferably used.
The scraper 66D is made of an elastic plate such as a phosphor bronze plate, a polyethylene terephthalate plate, or a polycarbonate plate, and is preferably brought into contact with a counter system that forms an acute angle with respect to the rotation direction of the flicker 66I.

  An antioxidant solid material (solid agent amount of antioxidant and zinc stearate) 66K is attached to the brush roller 66C by being pressed by a load spring 66S, and the brush roller 66C rotates while the antioxidant. The solid material 66K is abraded to supply an antioxidant to the surface of the photoreceptor 1.

  As the brush roller 66C, a conductive or semiconductive brush roller is used. Any material can be used as the brush constituent material of the brush roller 66C, but it is preferable to use a fiber-forming high molecular polymer that is hydrophobic and has a high dielectric constant. Examples of such a high molecular polymer include rayon, nylon, polycarbonate, polyester, methacrylic acid resin, acrylic resin, polyvinyl chloride, polyvinylidene chloride, polypropylene, polystyrene, polyvinyl acetate, styrene-butadiene copolymer, and chloride. Vinylidene-acrylonitrile copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicone resin, silicone-alkyd resin, phenol formaldehyde resin, styrene-alkyd resin, polyvinyl acetal (for example, Polyvinyl butyral). These resins can be used alone or as a mixture of two or more. Particularly preferred are rayon, nylon, polyester, acrylic resin and polypropylene.

  As the brush roller 66C, a conductive or semi-conductive material can be used, and a low resistance substance such as carbon can be contained in the constituent material and adjusted to an arbitrary specific resistance.

The thickness of one bristle used for the brush roller 66C is preferably 5 to 20 denier. If it is less than 5 denier, the surface deposits cannot be removed because there is no sufficient scratching force. On the other hand, if it is larger than 20 denier, the brush becomes rigid, so that the surface of the photoreceptor 1 is damaged and wear is advanced, and the life of the photoreceptor 1 is reduced.
“Denier” is a numerical value obtained by measuring a mass of 9000 m of the bristle (fiber) constituting the brush roller 66C in units of g (gram).

The brush hair density of the brush roller 66 </ ^b > C is 4.5 × 10 ² / cm ^{2 to} 2.0 × 10 ⁴ / cm ² (the number of brush hairs per square centimeter).
When the brush bristle density is less than 4.5 × 10 ² / cm ² , the rigidity is low and the rubbing force is weak, and the rubbing is uneven and the deposits cannot be removed uniformly. If it is larger than 2.0 × 10 ⁴ / cm ² , it becomes rigid and the rubbing force becomes strong, so that the photoreceptor 1 is excessively worn, and a defective image such as fogging due to sensitivity reduction or black streaks due to scratches is generated.

The biting amount of the brush roller 66C with respect to the photoreceptor 1 is preferably set to 0.4 to 1.5 mm.
This amount of biting means the load on the brush roller 66C generated by the relative movement of the photosensitive drum 1 and the brush roller 66C. This load corresponds to the rubbing force received from the brush roller 66C when viewed from the drum of the photosensitive member 1, and defining the range means that the photosensitive member 1 needs to be scraped with an appropriate force. To do.
Further, the amount of biting in is the length of biting into the interior when it is assumed that the brush bristles enter the interior linearly without bending on the surface of the photoreceptor 1 when the brush roller 66C is brought into contact with the photoreceptor 1. Say it.

  As the core material of the roller portion used for the brush roller 66C, metals such as stainless steel and aluminum, paper, plastics, etc. are mainly used, but are not limited thereto.

The brush roller 66 </ b> C preferably rotates so that the contact portion thereof moves in the same direction as the surface of the photoreceptor 1. When the contact portion moves in the opposite direction, if excessive toner is present on the surface of the photoreceptor 1, the toner removed by the brush roller 66C may spill out and stain the recording paper or the apparatus.
When the photoreceptor 1 and the brush roller 66C move in the same direction, the surface speed ratio between the two is preferably a value within a range of 1: 1 to 1-2.

  The image forming apparatus of the present invention is configured by integrally combining the above-described photosensitive member, developing unit, cleaning unit and the like as a process cartridge (image forming unit), and this image forming unit is connected to the apparatus main body. It may be configured to be detachable. In addition, a process cartridge (image forming unit) is formed by integrally supporting at least one of a charging unit, an exposure unit, a developing unit, a transfer unit, and a cleaning unit together with a photosensitive member, and is detachably attached to the apparatus main body. It is good also as a formation unit and a structure which can be attached or detached using guide means, such as a rail of an apparatus main body.

  The endless belt-like intermediate transfer body unit 7 includes an endless belt-like intermediate transfer body 70 as a second image carrier having a semiconductive endless belt shape that is wound around a plurality of rollers and is rotatably supported.

  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 as primary transfer means. Thus, a synthesized color image is formed. A transfer material (image support for carrying a fixed final image: for example, plain paper, transparent sheet, etc.) P housed in the paper feed cassette 20 is fed by a paper feed means 21 and includes a plurality of intermediate rollers 22A, After passing through 22B, 22C, 22D and the registration roller 23, it is conveyed to the secondary transfer roller 5b as the secondary transfer means, and is secondarily transferred onto the transfer material P, and the color images are collectively transferred. The transfer material P onto which the color image has been transferred is subjected to fixing processing by the fixing unit 24, is sandwiched between paper discharge rollers 25, and is placed on a paper discharge tray 26 outside the apparatus. Here, a transfer support for a toner image formed on a photosensitive member such as an intermediate transfer member or a transfer material is collectively referred to as a transfer medium.

  On the other hand, after the color image is transferred to the transfer material P by the secondary transfer roller 5b as the secondary transfer means, the residual toner is removed by the cleaning means 6b from the endless belt-shaped intermediate transfer body 70 in which the transfer material P is separated by curvature. The

  During the image forming process, the primary transfer roller 5Bk is always in contact with the photoreceptor 1Bk. The other primary transfer rollers 5Y, 5M, and 5C are in contact with the corresponding photoreceptors 1Y, 1M, and 1C, respectively, only during color image formation.

  The secondary transfer roller 5b contacts the endless belt-shaped intermediate transfer body 70 only when the transfer material P passes through the secondary transfer roller 5b.

  Further, the housing 8 can be pulled out from the apparatus main body A through the support rails 82L and 82R.

  The housing 8 includes image forming units 10Y, 10M, 10C, and 10Bk and an endless belt-shaped intermediate transfer body unit 7.

  The image forming units 10Y, 10M, 10C, and 10Bk are arranged in tandem in the vertical direction. An endless belt-shaped intermediate transfer body unit 7 is disposed on the left side of the photoreceptors 1Y, 1M, 1C, and 1Bk in the drawing. The endless belt-shaped intermediate transfer body unit 7 includes an endless belt-shaped intermediate transfer body 70 that can be rotated by winding rollers 71, 72, 73, 74, primary transfer rollers 5Y, 5M, 5C, 5Bk, and a cleaning unit 6b. Consists of.

  In the image forming apparatus shown in FIG. 3, a color laser printer is shown. However, the present invention can be similarly applied to a monochrome laser printer and a copy. The exposure light source may also be a light source other than a laser, such as an LED light source.

  According to the image forming apparatus as described above, by providing the photoconductor of the present invention, it is possible to form a high-quality image over a long period of time.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited only to a following example. In the following, “part” means “part by mass”.

[Photosensitive body preparation example 1]
The surface of an aluminum cylinder having a diameter of 60 mm was cut to prepare a conductive support [1] having a fine and rough surface.

(Formation of intermediate layer)
A dispersion having the following composition was diluted twice with the same solvent as described below, and allowed to stand overnight, followed by filtration (filter; using a lymesh 5 μm filter manufactured by Nihon Pall) to prepare a coating solution [1] for forming an intermediate layer. .
Binder resin: Polyamide resin “CM8000” (manufactured by Toray Industries, Inc.) 1 part Metal oxide particles: Titanium oxide “SMT500SAS” (manufactured by Teica) 3 parts Solvent: Methanol 10 parts Batch using a sand mill as a disperser for 10 hours Was distributed.
An intermediate layer [1] having a dry film thickness of 2 μm was formed on the conductive support [1] using the intermediate layer forming coating solution [1] by dip coating.

(Formation of charge generation layer)
Charge generation material: 20 parts of the following pigment (CG-1), binder resin: 10 parts of polyvinyl butyral resin “# 6000-C” (manufactured by Denki Kagaku Kogyo), solvent: 700 parts of t-butyl acetate, solvent: 4-methoxy 300 parts of -4-methyl-2-pentanone was mixed and dispersed for 10 hours using a sand mill to prepare a coating solution [1] for forming a charge generation layer. This charge generation layer forming coating solution [1] was applied onto the intermediate layer [1] by a dip coating method to form a charge generation layer [1] having a dry film thickness of 0.3 μm.

<Synthesis of Pigment (CG-1)>
(1) Synthesis of amorphous titanyl phthalocyanine 1,3-diiminoisoindoline; 29.2 parts are dispersed in 200 parts of o-dichlorobenzene, and titanium tetra-n-butoxide; 20.4 parts are added under a nitrogen atmosphere. For 5 hours at 150-160 ° C. After allowing to cool, the precipitated crystals were filtered, washed with chloroform, washed with 2% aqueous hydrochloric acid, washed with water, washed with methanol, and dried to obtain 26.2 parts (yield 91%) of crude titanyl phthalocyanine.
Next, the crude titanyl phthalocyanine was dissolved by stirring for 1 hour in 250 parts of concentrated sulfuric acid at 5 ° C. or less, and this was poured into 5000 parts of water at 20 ° C. The precipitated crystals were filtered and sufficiently washed with water to obtain 225 parts of a wet paste product.
This wet paste product was frozen in a freezer, thawed again, filtered and dried to obtain 24.8 parts of amorphous titanyl phthalocyanine (yield 86%).

(2) Synthesis of (2R, 3R) -2,3-butanediol adduct titanyl phthalocyanine (CG-1) 10.0 parts of the above amorphous titanyl phthalocyanine and (2R, 3R) -2,3-butanediol 94 parts (0.6 equivalent ratio) (equivalent ratio is equivalent ratio to titanyl phthalocyanine, hereinafter the same) was mixed in 200 parts of orthochlorobenzene (ODB) and stirred at 60 to 70 ° C. for 6.0 hours. After standing overnight, methanol was added to the reaction solution, and the resulting crystals were filtered. The crystals after filtration were washed with methanol (a pigment containing (2R, 3R) -2,3-butanediol adduct titanyl phthalocyanine). CG-1: 10.3 parts were obtained. In the X-ray diffraction spectrum of the pigment (CG-1), there are clear peaks at 8.3 °, 24.7 °, 25.1 °, and 26.5 °. There is a peak in the 576 and 648 in the mass spectra, O-Ti-O both absorption appears Ti = O near 970 cm ^-1, around 630 cm ^-1 in the IR spectrum. In addition, since thermal analysis (TG) has a mass loss of about 7% at 390 to 410 ° C., a 1: 1 adduct and a non-adduct (addition) of titanyl phthalocyanine and (2R, 3R) -2,3-butanediol (Not) presumed to be a mixture of titanyl phthalocyanine.
It was 31.2 m < ² > / g when the BET specific surface area of the obtained pigment (CG-1) was measured with the flow type specific surface area automatic measuring apparatus (Micrometrics flow soap type: Shimadzu Corporation).

(Formation of charge transport layer)
Charge transport material: 225 parts of the following compound A, binder resin: 300 parts of polycarbonate resin “Z300” (manufactured by Mitsubishi Gas Chemical), antioxidant: 6 parts of “Irganox 1010” (manufactured by Ciba Geigy Japan), solvent: THF (tetrahydrofuran) 1600 Part, solvent: 400 parts of toluene and 1 part of silicone oil “KF-50” (manufactured by Shin-Etsu Chemical Co., Ltd.) were mixed and dissolved to prepare a coating solution [1] for forming a charge transport layer.
The charge transport layer forming coating solution [1] was applied onto the charge generation layer [1] using a circular slide hopper coating apparatus to form a charge transport layer [1] having a dry film thickness of 20 μm.

(Formation of surface layer)
(1) Production of Composite Fine Particles Using the production apparatus shown in FIG. 6, composite fine particles [1] in which tin oxide is adhered to the surface of the barium sulfate core material were produced.
Specifically, 3500 cm ³ of pure water was introduced into the mother liquor tank (11), and then 900 g of a spherical barium sulfate core material having an average particle diameter D ₅₀ of 10 nm was introduced and circulated for 5 passes. The flow rate of the slurry flowing out from the mother liquor tank (11) was 2280 cm ³ / min. The stirring speed of the strong dispersion device (13) was 16000 rpm. The slurry after circulation completion females up to a total volume of 9000 cm ³ with pure water and there is 5 the path circulated by introduction of sodium stannate and 2.3 cm ³ of an aqueous sodium hydroxide solution (concentration 25 N) of 1600 g. A mother liquor was thus obtained. While this mother liquor is circulated so that the flow rate (S1) flowing out from the mother liquor tank (11) is 200 cm ³ , it is 20% in a homogenizer “magic LAB” (manufactured by IKA Japan Co., Ltd.) as a strong dispersion device (13). Sulfuric acid was supplied. The supply rate (S3) was set to 9.2 cm ³ / min. The volume of the homogenizer was 20 cm ³ and the stirring speed was 16000 rpm. Circulation was performed for 15 minutes, during which time sulfuric acid was continuously fed to the homogenizer. In this manner, particles having a tin oxide coating layer formed on the surface of the barium sulfate core material were obtained.
The slurry containing the obtained particles was repulp washed until the conductivity became 600 μS / cm or less, and then subjected to Nutsche filtration to obtain a cake. This cake was dried in air at 150 ° C. for 10 hours. Next, the dried cake was pulverized, and the pulverized powder was reduced and fired at 450 ° C. for 45 minutes in a 1% by volume H ₂ / N ₂ atmosphere. As a result, composite fine particles [1] in which tin oxide was adhered to the surface of the barium sulfate core material were obtained. The number average primary particle size of the composite fine particles [1] was 100 nm.

The composite fine particles [1] were subjected to a surface treatment as shown below using the above exemplified compound (S-15) as a surface treatment agent to produce surface-treated composite fine particles [1]. The number average primary particle size of the surface-treated composite fine particles [1] was 100 nm, and the volume resistivity was 6.7 × 10 ² [Ωcm].
First, the composite fine particles (1) 100 parts of a surface treatment agent (Example Compound _{(S-15): CH 2} = C (CH 3) COO (CH 2) 3 Si (OCH 3) 3) 30 parts of toluene / isopropyl alcohol Surface treatment was performed by putting a mixed solution of 300 parts of a mixed solvent of 1/1 (mass ratio) into a sand mill together with zirconia beads at about 40 ° C. and stirring at a rotational speed of 1500 rpm. Further, the treated mixture was taken out, put into a Henschel mixer, stirred at a rotational speed of 1500 rpm for 15 minutes, and then dried at 120 ° C. for 3 hours to finish the surface treatment, thereby obtaining surface-treated composite fine particles [1]. .

(2) Formation of surface layer Surface-treated composite fine particles [1] 80 parts, polyfunctional radical polymerizable compound: 100 parts of the exemplified compound (M1), solvent: 320 parts of 2-butanol, solvent: 80 parts of tetrahydrofuran under light shielding After mixing for 5 hours using a sand mill as a disperser, charge transporting compound: 20 parts of the exemplified compound (CTM-8) and polymerization initiator: 10 parts of the exemplified compound (P2) are added, and the mixture is protected from light. And dissolved by stirring to prepare a surface layer-forming coating solution [1]. The surface layer forming coating solution [1] is applied onto the charge transport layer [1] using a circular slide hopper coating device to form a coating film, and irradiated with ultraviolet rays for 1 minute using a metal halide lamp, followed by drying. A surface layer [1] having a thickness of 5.0 μm was formed to produce a photoreceptor [1]. In the surface layer [1], the number density of the composite fine particles was 45 / μm ³ .

  In the manufacturing apparatus shown in FIG. 6, reference numerals 12 and 14 are circulation pipes that form a circulation path between the mother liquor tank 11 and the strong dispersion apparatus 13, and reference numerals 15 and 16 are provided in the circulation pipes 12 and 14. The reference numeral 11a indicates a stirring blade, the reference numeral 13a indicates a stirring portion, the reference numerals 11b and 13b indicate shafts, and the reference numerals 11c and 13c indicate motors.

[Photoconductor Preparation Examples 2 to 12]
In the formation of the surface layer in Preparation Example 1 of the photoreceptor, the photoreceptors [2] to [2] to [2] to [2] are similarly used except that the type and amount of composite fine particles used and the type of the charge transporting compound are changed according to Table 1. 12] was produced.
The composite fine particles [2] to [11] were obtained by the following production examples.

[Production Example of Composite Fine Particle [2]]
Using the production apparatus shown in FIG. 6, composite fine particles [2] in which zinc oxide is adhered to the surface of the barium sulfate core material were produced.
Specifically, 3500 cm ³ of pure water was introduced into the mother liquor tank (11), and then 900 g of a spherical barium sulfate core material having an average particle diameter D ₅₀ of 30 nm was introduced and circulated for 5 passes. The flow rate of the slurry flowing out from the mother liquor tank (11) was 2280 cm ³ / min. The stirring speed of the strong dispersion device (13) was 16000 rpm. After completion of the circulation, the slurry was made up to a total volume of 9000 cm ³ with pure water, and 1000 g of anhydrous zinc chloride was added thereto for circulation in 5 passes. A mother liquor was thus obtained. While this mother liquor is circulated so that the flow rate (S1) flowing out from the mother liquor tank (11) is 10 L / min, the homogenizer “T50” (manufactured by IKA Japan Co., Ltd.) as a strong dispersion device (13) is 20%. An aqueous sodium hydroxide solution was supplied. The supply rate (S3) was 9.2 cm ³ / min, and the pH was 5.0. The volume of the homogenizer was 500 cm ³ and the stirring speed was 16000 rpm. Circulation was performed for 15 minutes, during which time sulfuric acid was continuously fed to the homogenizer. In this way, particles having a zinc oxide coating layer formed on the surface of the barium sulfate core material were obtained.
The slurry containing the obtained particles was repulp washed until the conductivity became 600 μS / cm or less, and then subjected to Nutsche filtration to obtain a cake. This cake was dried in air at 150 ° C. for 10 hours. Next, the dried cake was pulverized, and the pulverized powder was reduced and fired at 450 ° C. for 45 minutes in the air. As a result, composite fine particles [2] in which zinc oxide was adhered to the surface of the barium sulfate core material were obtained. The composite fine particles [2] had a number average primary particle size of 200 nm and a volume resistivity of 5.3 × 10 ⁻¹ [Ωcm].

[Production Example of Composite Fine Particle [3]]
To 3 L of pure water, 0.1 L of 35% hydrochloric acid was added and heated to 75 ° C. In this hydrochloric acid acidic solution, 300 g of an alumina core material having an average particle diameter D ₅₀ of 30 nm is suspended, and while stirring, a titanium tetrachloride aqueous solution (50 mass% as Ti content) is added thereto at a rate of 36 g per hour. Along with quantitative addition, caustic soda dissolved in 10% by mass was added at a rate of 360 ml per hour. The slurry containing the obtained particles is repulp washed until the electrical conductivity becomes 100 μS / cm or less, and then subjected to Nutsche filtration to obtain a cake, followed by vacuum drying at 150 ° C., and titanium oxide on the surface of the alumina core material. To obtain composite fine particles [3]. The composite fine particles [3] had a number average primary particle size of 150 nm and a volume resistivity of 2.4 × 10 ⁴ [Ωcm].

[Production Example of Composite Fine Particle [4]]
Using the production apparatus shown in FIG. 6, composite fine particles [4] in which tin oxide was adhered to the surface of the silica core material were produced.
Specifically, 3500 cm ³ of pure water was introduced into the mother liquor tank (11), and then 900 g of spherical silica core material having an average particle diameter D ₅₀ of 25 nm was introduced and circulated for 5 passes. The flow rate of the slurry flowing out from the mother liquor tank (11) was 2280 cm ³ / min. The stirring speed of the strong dispersion device (13) was 16000 rpm. After completion of the circulation, the slurry was made up to a total volume of 9000 cm ³ with pure water, and 1600 g of sodium stannate was added thereto to circulate for 5 passes. A mother liquor was thus obtained. While this mother liquor was circulated so that the flow rate (S1) flowing out from the mother liquor tank (11) was 200 cm ³ , 20% sulfuric acid was added to a homogenizer “T50” (manufactured by IKA Japan) as a strong dispersion device (13). Supplied. The supply rate (S3) was set to 9.2 cm ³ / min. The volume of the homogenizer was 500 cm ³ and the stirring speed was 16000 rpm. Circulation was performed for 15 minutes, during which time sulfuric acid was continuously fed to the homogenizer. In this way, particles having a tin oxide coating layer formed on the surface of the silica core material were obtained. The slurry containing the obtained particles was repulp washed until the conductivity became 600 μS / cm or less, and then subjected to Nutsche filtration to obtain a cake. This cake was dried in air at 150 ° C. for 10 hours. Next, the dried cake was pulverized, and the pulverized powder was reduced and fired at 700 ° C. for 1 hour in an atmosphere of 1% by volume H ₂ / N ₂ . Thereby, composite fine particles [4] in which tin oxide was adhered to the surface of the silica core material were obtained. The composite fine particles [4] had a number average primary particle size of 300 nm and a volume resistivity of 1.2 × 10 ¹ [Ωcm].
Thereafter, surface treatment was performed in the same manner as the composite fine particles [1] to obtain surface-treated composite fine particles [4].

[Production Example of Composite Fine Particle [5]]
In the preparation example of the composite fine particles (3), alumina core, other that the average particle diameter D ₅₀ was changed to barium sulfate core is 30nm in the same manner, titanium oxide deposited on the surface of the barium sulfate core Thus obtained composite fine particles [5] were obtained. The composite fine particles [5] had a number average primary particle size of 100 nm and a volume resistivity of 7.8 × 10 ⁶ [Ωcm].

[Production Example of Composite Fine Particle [6]]
In the preparation example of the composite fine particles (3), alumina core, other that the average particle diameter D ₅₀ was changed to silica core is 30nm in the same manner, with titanium oxide on the surface of the silica core is attached Composite fine particles [6] were obtained. The composite fine particles [6] had a number average primary particle size of 250 nm and a volume resistivity of 8.1 × 10 ⁵ [Ωcm].

[Production Example of Composite Fine Particle [7]]
Using the production apparatus shown in FIG. 6, composite fine particles [7] in which a composite oxide of indium and tin (indium tin oxide (ITO)) was attached to the surface of the barium sulfate core material were produced.
Specifically, 3500 cm ³ of pure water was introduced into the mother liquor tank (11), and then 900 g of a spherical barium sulfate core material having an average particle diameter D ₅₀ of 10 nm was introduced and circulated for 5 passes. The flow rate of the slurry flowing out from the mother liquor tank (11) was 2280 cm ³ / min. The stirring speed of the strong dispersion device (13) was 16000 rpm. The slurry after the circulation was made up to a total volume of 9000 cm ³ with pure water, and 5 g of tin chloride hydrochloric acid solution (44%) and 976 g of indium nitrate aqueous solution (100 g / 1000 cm ³ , specific gravity 1.6 g / cm ³ ) Sodium stannate was added and circulated for 5 passes. A mother liquor was thus obtained. While this mother liquor is circulated so that the flow rate (S1) flowing out from the mother liquor tank (11) is 10 L / min, the homogenizer “T50” (manufactured by IKA Japan Co., Ltd.) as a strong dispersion device (13) is 20%. Sodium hydroxide was fed. The supply rate (S3) was 9.2 cm ³ / min, and the pH was 3.0. The volume of the homogenizer was 500 cm ³ and the stirring speed was 16000 rpm. Circulation was performed for 15 minutes, during which time sulfuric acid was continuously fed to the homogenizer. In this way, particles were obtained in which a coating layer of indium and tin hydroxide was formed on the surface of the barium sulfate core material. The slurry containing the obtained particles was repulp washed until the conductivity became 600 μS / cm or less, and then subjected to Nutsche filtration to obtain a cake. This cake was dried in air at 150 ° C. for 10 hours. Next, the dried cake was pulverized, and the pulverized powder was reduced and fired at 450 ° C. for 45 minutes in a 1% by volume H ₂ / N ₂ atmosphere. As a result, composite fine particles [7] in which a composite oxide (ITO) of indium and tin was adhered to the surface of the barium sulfate core material were obtained. The composite fine particles [7] had a number average primary particle size of 100 nm and a volume resistivity of 2.9 × 10 ⁻³ [Ωcm].

[Production Example of Composite Fine Particle [8]]
In the preparation example of the composite fine particles (4), a silica core, other that the average particle diameter D ₅₀ was changed to an alumina core is 30nm in the same manner, and tin oxide on the surface of the alumina core is attached Composite fine particles [8] were obtained. The composite fine particles [8] had a number average primary particle size of 200 nm and a volume resistivity of 4.8 × 10 ² [Ωcm].
Thereafter, surface treatment was performed in the same manner as the composite fine particles [1] to obtain surface-treated composite fine particles [8].

[Production Example of Composite Fine Particle [9]]
In the preparation example of a composite fine particles [2], barium sulfate core, other that the average particle diameter D ₅₀ was changed to silica core is 10nm in the same manner, the zinc oxide is deposited on the surface of the silica core To obtain composite fine particles [9]. The composite fine particles [9] had a number average primary particle size of 50 nm and a volume resistivity of 3.5 × 10 ⁻² [Ωcm].

[Production Example of Composite Fine Particle [10]]
In the preparation example of a composite fine particles [1], barium sulfate core, other that the average particle diameter D ₅₀ was changed to barium sulfate core is 100nm in the same manner, the tin oxide on the surface of the barium sulfate core Composite fine particles [10] adhered were obtained. The composite fine particles [10] had a number average primary particle size of 500 nm and a volume resistivity of 9.5 × 10 ¹ [Ωcm].

[Production Example of Composite Fine Particle [11]]
In the preparation example of the composite fine particles (3), alumina core, other that the average particle diameter D ₅₀ was changed to barium sulfate core is 10nm in the same manner, titanium oxide deposited on the surface of the barium sulfate core Thus obtained composite fine particles [11] were obtained. The composite fine particles [11] had a number average primary particle size of 20 nm and a volume resistivity of 2.8 × 10 ² [Ωcm].

[Examples 1-9, Comparative Examples 1-3]
Evaluation was performed by mounting the photoreceptors [1] to [12] on an evaluation machine “bizhub PRO C6501” (manufactured by Konica Minolta Business Technologies, Inc.) similar to the configuration of the image forming apparatus shown in FIG. . A semiconductor laser having a wavelength of 780 nm was used as an exposure light source of the evaluation machine “bizhub PRO C6501”.
In a high-temperature and high-humidity environment with a temperature of 30 ° C. and a humidity of 85%, an endurance test was performed in which 300,000 double-sided continuous printing was performed on each character image with an image ratio of 6% by A4 horizontal feed. The potential stability, image flow and cleaning properties were evaluated.

(1) Evaluation of abrasion resistance It evaluated by the amount of film thickness wear of the surface layer of the photoreceptor before and after the durability test.
Specifically, the film thickness of the surface layer was measured at 10 points at random on the uniform film thickness portion (excluding the film thickness fluctuation portion at the front end portion and rear end portion of the coating), and the average The value is the film thickness of the surface layer. As the film thickness measuring device, an eddy current type film thickness measuring device “EDDY560C” (manufactured by HELMUT FISCHER GMBTE CO) was used, and the difference in the film thickness of the surface layer before and after the durability test was calculated as a film thickness depletion amount (μm). If the film thickness was less than 4 μm, it was evaluated as practical.

(2) Evaluation of electric potential stability It evaluated by the magnitude | size of the electric potential fluctuation | variation of the exposure part electric potential before and behind an endurance test.
Specifically, the initial charging potential was adjusted to 600 ± 50 V, and the amount of change (ΔV) in the exposed portion potential before the endurance test and after 300,000 sheets was calculated. If the amount of change in the exposed portion potential was 100 V or less, it was evaluated as practical.

(3) Evaluation of image flow Evaluation of image flow was performed by observing the output image with a microscope and visually.
Specifically, in a high-temperature and high-humidity (temperature: 30 ° C./humidity: 80%) environment, using “bizhub PRO C6501” (manufactured by Konica Minolta, Inc.), a half image is output on A4 paper, The obtained image was observed using a digital microscope “VHX-600” manufactured by KEYENCE, and visually evaluated according to the following evaluation criteria. The judgment criteria are as follows.
(Double-circle): The outline of a dot can be judged visually visually. (Good)
A: The outline of the dot is blurred, but the outline can be judged visually. (No practical problem)
X: The outline of a dot cannot be judged completely visually. (There are practical problems)

(4) Evaluation of cleaning property Cleaning property in the durability test was evaluated according to the following evaluation criteria.
The judgment criteria are as follows.
-Evaluation criteria-
A: No toner slipping out, blade wear width less than 20 μm (good)
○: No toner slipping, blade wear width of 20 μm or more (no problem in practical use)
X: Toner slipping out (practical problem)

1,1Y, 1M, 1C, 1Bk photoconductor 2Y, 2M, 2C, 2Bk charging means 3Y, 3M, 3C, 3Bk exposure means 4Y, 4M, 4C, 4Bk developing means 5Y, 5M, 5C, 5Bk primary transfer roller 5b second Next transfer roller 6, 6Y, 6M, 6C, 6Bk, 6b Cleaning means 7 Intermediate transfer body unit 8 Housing 10Y, 10M, 10C, 10Bk Image forming unit 11 Mother liquid tank 11a Stirring blade 11b Shaft 11c Motor 12 Circulating piping 13 Strong dispersion Device 13a Stirrer 13b Shaft 13c Motor 14 Circulation Piping 15 Pump 16 Pump 21 Paper Feeding Unit 20 Paper Feeding Cassette 22A, 22B, 22C, 22D Intermediate Roller 23 Registration Roller 24 Fixing Unit 25 Paper Discharge Roller 26 Paper Discharge Tray 66A Cleaning Blade 66B Support member 6C Brush roller 66D Scraper 66E Rotating shaft 66G Load spring 66I Flicker 66J Conveying screw 66S Load spring 66K Solid material 70 Endless belt-shaped intermediate transfer member 71, 72, 73, 74 Roller 82L, 82R Support rail P Transfer material 100 Surface layer 101 Composite Particulates 251 Substrate 254 Storage tank 255 Pumping pump 260 Coating head 261 Coating liquid outlet 262 Coating liquid distribution slit 263 Coating liquid distribution chamber 264 Supply pipe 265 Slide surface 266 Lip part 267 Discharge port L Coating liquid F Coating film

Claims (8)

In an electrophotographic photosensitive member in which a photosensitive layer is formed on a conductive support and a surface layer is formed on the photosensitive layer,
The surface layer is formed by attaching a conductive metal oxide to the surface of a core material made of an insulating material in a cured resin obtained by polymerizing a compound having two or more radically polymerizable functional groups. a volume resistivity of 10 ^-3 to 10 ⁷ [Ωcm], composite fine particles having an average particle diameter of 50 to 300 nm, and state, and are not charge-transporting compound is in a content,
The core material in the composite fine particles is at least one selected from barium sulfate, alumina and silica,
The conductive metal oxide in the composite fine particles is at least one selected from tin oxide, titanium oxide, zinc oxide, zirconia and indium tin oxide,
When the conductive metal oxide is tin oxide composite fine particles, the composite fine particles are obtained by surface treatment with a surface treatment agent comprising a compound having a radical polymerizable functional group. Photoconductor. 2. The electrophotographic photoreceptor according to claim 1, wherein the number density of the composite fine particles per unit volume of the surface layer is 1 to 550 [pieces / [mu] m < ³ >]. The electrophotographic photosensitive member according to claim 1, wherein the charge transporting compound is represented by the following general formula (1).

[In General Formula (1), R ¹ and R ² are each independently a hydrogen atom or a methyl group, and R ³ is a linear or branched alkyl group having 1 to 5 carbon atoms. ] The electrophotographic photosensitive member according to claim 1, wherein the core material of the composite fine particles is barium sulfate . The electrophotographic photosensitive member according to claim 1, wherein the radical polymerizable functional group in the surface treatment agent is an acryloyl group or a methacryloyl group . The composite fine particles are:
When the core material is barium sulfate, the conductive metal oxide is any one of tin oxide, zinc oxide, titanium oxide, and indium tin oxide,
When the core material is alumina, the conductive metal oxide is either titanium oxide or tin oxide,
6. The electrophotographic photosensitive member according to claim 1 , wherein when the core material is silica, the conductive metal oxide is any one of tin oxide, titanium oxide, and zinc oxide. body.   An electrophotographic photoreceptor, charging means for charging the surface of the electrophotographic photoreceptor, exposure means for forming an electrostatic latent image on the surface of the electrophotographic photoreceptor, and developing the electrostatic latent image with toner. Developing means for forming a toner image, transfer means for transferring the toner image to a transfer material, fixing means for fixing the toner image transferred to the transfer material, and cleaning for removing residual toner on the electrophotographic photosensitive member Means and
  An image forming apparatus, wherein the electrophotographic photosensitive member is the electrophotographic photosensitive member according to claim 1.   The image forming apparatus according to claim 7, wherein the cleaning unit is a blade.