JP2013200534A - Electrophotographic photoreceptor, image forming apparatus, and process cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor that suppresses the occurrence of ghost in an image to be formed.SOLUTION: An electrophotographic photoreceptor includes: a support 1; an undercoat layer 2 that contains at least metal oxide particles and a binder resin, and has the mass change amount from a temperature 30°C to 130°C by differential thermal/thermogravimetric simultaneous measurement of 0.65 mass% or less; and a photosensitive layer 3 in this order.

Description

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

  An electrophotographic image forming apparatus has high speed and high printing quality, and is used in image forming apparatuses such as copying machines and laser beam printers. As a photoreceptor used in an image forming apparatus, an organic photoreceptor using an organic photoconductive material has become the mainstream. When producing an organic photoreceptor, for example, an undercoat layer is often formed on a support made of aluminum or the like, and then a photosensitive layer, in particular, a photosensitive layer comprising a charge generation layer and a charge transport layer is often formed.

  For example, in Patent Document 1, in an electrophotographic photosensitive member having a photosensitive layer on an Al support, an undercoat layer is provided between the support and the photosensitive layer, and the undercoat layer is a water-soluble or alcohol-soluble resin, conductive An electron composed of a polymer, an electrolyte-based additive, and an inorganic pigment, wherein the undercoat layer has a moisture content of 0.02 g or less per 1 g of the undercoat layer when placed in an atmosphere of 20 ° C. and 90% RH for 20 hours. A photographic photoreceptor is disclosed.

Japanese Patent Laid-Open No. 03-150572

  An object of the present invention is to provide an electrophotographic photosensitive member in which the occurrence of ghost in the formed image is suppressed.

The above problem is solved by the following means. That is,
The invention according to claim 1
A support;
An undercoat layer containing at least metal oxide particles and a binder resin, and having a mass change amount of not more than 0.65% by mass from a temperature of 30 ° C. to 130 ° C. in suggested thermogravimetric simultaneous measurement;
A photosensitive layer;
In this order.

The invention according to claim 2
2. The electrophotographic photosensitive member according to claim 1, wherein the undercoat layer has a resistance value in an AC impedance measurement of 1 × 10 ⁸ Ω to 1 × 10 ¹⁰ Ω.

The invention according to claim 3
An electrophotographic photoreceptor according to claim 1;
A charging device for charging the surface of the electrophotographic photosensitive member;
An electrostatic latent image forming apparatus for forming an electrostatic latent image on the surface of the charged electrophotographic photosensitive member;
A developing device for developing the electrostatic latent image formed on the surface of the electrophotographic photosensitive member with toner to form a toner image;
A transfer device for transferring a toner image formed on the surface of the electrophotographic photosensitive member to a recording medium;
An image forming apparatus.

The invention according to claim 4
The electrophotographic photoreceptor according to claim 1,
It is a process cartridge that can be attached to and detached from the image forming apparatus.

  According to the invention of claim 1, it is formed as compared with the case where there is no subbing layer in which the mass change amount from the temperature 30 ° C. to 130 ° C. in the suggested thermothermal weight measurement is 0.65% by mass or less. An electrophotographic photosensitive member in which the occurrence of ghost in an image is suppressed is provided.

According to the invention according to claim 2, the occurrence of leakage is suppressed as compared with the case where the resistance value in the AC impedance measurement is 1 × 10 ⁸ Ω or more and 1 × 10 ¹⁰ Ω or less, and no undercoat layer is provided. Provided is an electrophotographic photosensitive member that provides stable potential characteristics even when used repeatedly.

  The invention according to claim 3 does not include an electrophotographic photosensitive member provided with an undercoat layer whose mass change amount from a temperature of 30 ° C. to 130 ° C. in the suggested thermothermogravimetric simultaneous measurement is 0.65% by mass or less. Compared to the case, an image forming apparatus in which the occurrence of ghost in an image is suppressed is provided.

  The invention according to claim 4 does not include an electrophotographic photosensitive member provided with an undercoat layer whose mass change from a temperature of 30 ° C. to 130 ° C. is 0.65% by mass or less in the simultaneous thermothermogravimetric measurement. Compared to the case, a process cartridge in which the occurrence of ghost in an image is suppressed is provided.

It is the schematic which shows an example of the layer structure of the electrophotographic photoreceptor which concerns on this embodiment. It is the schematic which shows the other example of the layer structure of the electrophotographic photoreceptor which concerns on this embodiment. It is the schematic which shows the other example of the layer structure of the electrophotographic photoreceptor which concerns on this embodiment. It is the schematic which shows the other example of the layer structure of the electrophotographic photoreceptor which concerns on this embodiment. It is the schematic which shows the other example of the layer structure of the electrophotographic photoreceptor which concerns on this embodiment. It is the schematic which shows the other example of the layer structure of the electrophotographic photoreceptor which concerns on this embodiment. 1 is a schematic configuration diagram illustrating an image forming apparatus according to an exemplary embodiment. It is a schematic block diagram which shows the image forming apparatus which concerns on other this embodiment.

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

<Electrophotographic photoreceptor>
The electrophotographic photoreceptor according to the exemplary embodiment (hereinafter also simply referred to as “photoreceptor”) includes a support, at least metal oxide particles, and a binder resin, and suggests thermothermogravimetric simultaneous measurement (TG / DTA measurement). The undercoat layer has a mass change amount of 0.65% by mass or less from 30 ° C. to 130 ° C. and the photosensitive layer in this order.

  Conventionally, in an electrophotographic image forming apparatus provided with a photoreceptor as an electrostatic latent image holding member, a ghost image defect may occur in the formed image. The mechanism by which this ghost occurs is not necessarily clear, but is presumed as follows. For example, in the case of an image forming system in which reversal development is performed after negatively charging a multi-layered photoreceptor having a charge generation layer and a charge transport layer, a part of the holes generated by image exposure is in the charge generation layer. And the surface potential is lowered by moving to the surface of the charge transport layer immediately after the charging step of the next cycle. As a result, it is presumed that a phenomenon called so-called positive ghost, in which the image of the previous cycle appears deeply, occurs. On the other hand, if some of the holes generated by image exposure accumulate at the interface between the charge generation layer and the charge transport layer and remain without being released in the next cycle, the effective electric field strength in the charge generation layer It is presumed that a phenomenon called so-called negative ghost, in which the image of the previous cycle appears thinly, occurs due to a decrease in the number of charges generated by image exposure.

Here, in an electrophotographic image forming apparatus, the resistance value in the undercoat layer of the photoreceptor may increase as the image formation is repeated, and the negative ghost may occur if the resistance value increases excessively. there were.
In particular, in recent years, development of image forming apparatuses that do not provide a charge eliminating device that performs the function of erasing the history of the previous cycle by irradiating light on the entire surface of the photosensitive member before charging has been actively performed. . In the image forming apparatus that does not have the static eliminator, there is a method of reducing the positive ghost due to the history of the previous cycle by making the resistance value of the undercoat layer higher, but in this configuration, in the undercoat layer When the resistance value increases, the critical value is easily exceeded, and the occurrence of the negative ghost sometimes becomes remarkable.

On the other hand, in the photoconductor according to this embodiment, the mass change amount from the temperature of 30 ° C. to 130 ° C. in the simultaneous thermogram measurement (TG / DTA measurement) of the undercoat layer is 0.65% by mass or less. Thereby, generation | occurrence | production of a negative ghost is suppressed effectively.
The mechanism by which this effect is exerted is not necessarily clear, but is presumed to be due to moisture mixed in the undercoat layer during the production of the photoreceptor. Specifically, when moisture is mixed into the undercoat layer, impurities such as moisture enter the oxygen vacancies of the metal oxide to form traps for trapping charges, and the resistance of the undercoat layer is increased. It is thought that the number of charges decreases, resulting in a negative ghost. In addition, the undercoat layer is relaxed by the entry of impurities such as moisture, and the distance between the conductive agents increases because the distance between the metal oxides as the conductive agent increases, resulting in an increase in the resistance of the undercoat layer. Therefore, it is considered that negative ghost is generated. However, the undercoat layer of the photoconductor according to this embodiment has a mass change amount from 30 ° C. to 130 ° C. within the above range, and the mass change amount from 30 ° C. to 130 ° C. is the moisture content. Considered as an indicator. In other words, since the moisture content in the undercoat layer is controlled within the above range, it is assumed that the increase in resistance of the undercoat layer caused by moisture is suppressed, and as a result, the occurrence of negative ghost is suppressed. The

  In addition, the mass change amount from the temperature 30 ° C. to 130 ° C. in the suggested thermothermogravimetric simultaneous measurement (TG / DTA measurement) is more preferably 0.5% by mass or less, and more preferably 0.3% by mass or less. Preferably, the lower the rate of mass change, the better.

-Measurement of mass change rate-
Here, in the measurement of the mass change rate in the undercoat layer, first, the undercoat layer is peeled off from the photoconductor, and TG / DTA6300 (manufactured by SII Nanotechnology Co., Ltd.) is used. It is performed by measuring the amount of mass change when the temperature is increased at a rate of increase of 10 ° C./min.

-Means for achieving mass change rate-
The means for controlling the mass change rate in the undercoat layer within the above range is not particularly limited. For example, after the undercoat layer is formed on the support by the method described later, further drying treatment is performed. A method is mentioned. The drying treatment may be performed after forming an undercoat layer and further forming another layer such as a photosensitive layer (for example, a charge generation layer or a charge transport layer) on the undercoat layer. You may carry out in the state which is not formed.
As a drying method, it is particularly preferable to perform vacuum drying. In addition, as for drying conditions, when not vacuum-drying, temperature is 90 to 120 degreeC, and 110 to 120 degreeC is more preferable. The time is preferably from 20 minutes to 1 hour, more preferably from 20 minutes to 30 minutes. When performing vacuum drying, the temperature is preferably 70 ° C. or higher and 120 ° C. or lower, and more preferably 70 ° C. or higher and 100 ° C. or lower. The time is preferably 30 minutes or more, more preferably 1 hour or more, and still more preferably 3 hours or more.

-Structure of photoconductor-
Next, the layer configuration of the photoreceptor according to the present embodiment will be described. 1 to 6 are schematic views showing examples of the layer structure of the photoreceptor according to the present embodiment.
The photoconductor shown in FIG. 1 includes a support 1, an undercoat layer 2 formed on the support 1, and a photosensitive layer 3 formed on the undercoat layer 2. Further, as shown in FIG. 2, the photosensitive layer 3 may have a two-layer structure of a charge generation layer 31 and a charge transport layer 32. Further, as shown in FIGS. 3 and 4, the protective layer 5 may be provided on the photosensitive layer 3 or the charge transport layer 32. 5 and 6, an intermediate layer 4 may be provided between the undercoat layer 2 and the photosensitive layer 3 or between the undercoat layer 2 and the charge generation layer 31.

(Support)
As the support 1, a conductive support is used. For example, the support 1 is configured using a metal or an alloy such as aluminum, copper, zinc, stainless steel, chromium, nickel, molybdenum, vanadium, indium, gold, or platinum. Examples include metal plates, metal drums, and metal belts, or paper, plastic films, belts, etc. coated, vapor-deposited, or laminated with conductive polymers, conductive compounds such as indium oxide, and metals or alloys such as aluminum, palladium, and gold. It is done. Here, “conductive” means that the volume resistivity is less than 10 ¹³ Ωcm.

  If the photoreceptor according to this embodiment is used in a laser printer, the surface of the support 1 is desirably roughened to a centerline average roughness Ra of 0.04 μm to 0.5 μm. However, when non-interfering light is used as a light source, roughening is not particularly required.

  Surface roughening methods include wet honing by suspending an abrasive in water and spraying it on the support, or centerless grinding and anodization in which the support is brought into contact with a rotating grindstone and continuously ground. Processing is desirable.

  Further, as another roughening method, without roughening the surface of the support 1, the conductive or semiconductive powder is dispersed in the resin to form a layer on the surface of the support, A method of roughening with particles dispersed in the layer is also desirably used.

  Here, the roughening treatment by anodic oxidation is to form an oxide film on the aluminum surface by anodizing in an electrolyte solution using aluminum as an anode. Examples of the electrolyte solution include a sulfuric acid solution and an oxalic acid solution. However, since the porous anodic oxide film formed by anodic oxidation is chemically active as it is, fine pores of the anodic oxide film may be added to pressurized water vapor or boiling water (metal salt such as nickel may be added). It is desirable to perform a sealing treatment to block the volume expansion due to the hydration reaction, and to change to a more stable hydrated oxide. The thickness of the anodic oxide film is desirably 0.3 μm or more and 15 μm or less.

Further, the support 1 may be subjected to treatment with an acidic aqueous solution or boehmite treatment.
The treatment with an acidic treatment solution containing phosphoric acid, chromic acid and hydrofluoric acid is carried out as follows. First, an acidic treatment liquid is prepared. The mixing ratio of phosphoric acid, chromic acid and hydrofluoric acid in the acidic treatment liquid is such that phosphoric acid is in the range of 10% by mass to 11% by mass, chromic acid is in the range of 3% by mass to 5% by mass, and hydrofluoric acid is 0. The concentration of these acids is preferably in the range of 13.5 mass% to 18 mass%. The treatment temperature is desirably 42 ° C. or higher and 48 ° C. or lower. The film thickness is preferably from 0.3 μm to 15 μm.

  The boehmite treatment is performed by immersing in pure water of 90 ° C. or more and 100 ° C. or less for 5 minutes or more and 60 minutes or less, or by contacting with heated steam of 90 ° C. or more and 120 ° C. or less for 5 minutes or more and 60 minutes or less. The film thickness is preferably 0.1 μm or more and 5 μm or less. This is further anodized using an electrolyte solution with lower film solubility than other types such as adipic acid, boric acid, borate, phosphate, phthalate, maleate, benzoate, tartrate, citrate, etc. It may be processed.

(Undercoat layer)
In the undercoat layer 2 in this embodiment, the mass change amount from the temperature of 30 ° C. to 130 ° C. in the simultaneous thermothermal weight measurement (TG / DTA measurement) is 0.65% by mass or less.
The undercoat layer 2 is configured as a layer containing at least metal oxide particles and a binder resin.

-Binder resin As the binder resin contained in the undercoat layer 2, any known resin can be used. For example, acetal resins such as polyvinyl butyral, polyvinyl alcohol resin, casein, polyamide resin, cellulose resin, gelatin, Polyurethane resin, polyester resin, polyether resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinyl acetate resin, vinyl chloride-vinyl acetate-maleic anhydride resin, silicone resin, silicone-alkyd resin, urea resin, phenol resin, Known polymer resin compounds such as phenol-formaldehyde resin, melamine resin, unsaturated urethane resin, polyester resin, alkyd resin, epoxy resin, etc., charge transport resin having a charge transport group and conductive resin such as polyaniline, etc. Use It is done. Among them, resins that are insoluble in the upper layer coating solvent are desirably used, and in particular, thermosetting resins such as urea resins, phenol resins, phenol-formaldehyde resins, melamine resins, urethane resins, unsaturated polyester resins, alkyd resins, epoxy resins, A resin obtained by reaction of at least one resin selected from the group consisting of polyamide resin, polyester resin, polyether resin, acrylic resin, polyvinyl alcohol resin and polyvinyl acetal resin with a curing agent is desirably used.
When these are used in combination of two or more, the mixing ratio is set as necessary.

Metal oxide particles As metal oxide particles, powder resistance (volume resistivity) of 10 ² Ω · cm or more and 10 ¹¹ Ω · cm or less is desirably used.

  As the metal oxide particles, it is desirable to use metal oxide particles (metal oxide particles) such as tin oxide, titanium oxide, zinc oxide, and zirconium oxide, and zinc oxide is particularly desirable.

The volume average particle size of the metal oxide particles is preferably in the range of 50 nm to 200 nm, and more preferably in the range of 70 nm to 120 nm.
The volume average particle size of the metal oxide particles is measured using a laser diffraction particle size distribution measuring device (LA-700: manufactured by Horiba, Ltd.). As a measuring method, the sample in the state of dispersion is adjusted to 2 g in solid content, ion-exchanged water is added thereto to make 40 ml, and this is put into a cell until an appropriate concentration is obtained. Measure after 2 minutes. The obtained volume average particle diameter for each channel is accumulated from the smaller one, and the place where the accumulation reaches 50% is defined as the volume average particle diameter.

Further, as the metal oxide particles, those having a specific surface area of 10 m ² / g or more by the BET method are desirably used.

  The content (solid content ratio) of the metal oxide particles in the undercoat layer is desirably in the range of 10% by mass to 80% by mass, and more desirably in the range of 30% by mass to 60% by mass. .

  Further, the metal oxide particles may be subjected to a surface treatment, or may be used by mixing two or more kinds such as those having different surface treatments or particles having different particle diameters.

  The metal oxide particles may be subjected to a surface treatment. The surface treatment agent is selected from known materials. For example, a silane coupling agent, a titanate coupling agent, an aluminum coupling agent, a surfactant, and the like can be given. In particular, a silane coupling agent is desirably used. Furthermore, a silane coupling agent having an amino group is also desirably used.

  Any material may be used as the silane coupling agent having an amino group. Specific examples include γ-aminopropyltriethoxysilane, N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, N -Β- (aminoethyl) -γ-aminopropylmethylmethoxysilane, N, N-bis (β-hydroxyethyl) -γ-aminopropyltriethoxysilane, and the like. However, it is not limited to these.

  Two or more silane coupling agents may be mixed and used. Examples of silane coupling agents that may be used in combination with the silane coupling agent having an amino group include vinyltrimethoxysilane, γ-methacryloxypropyl-tris (β-methoxyethoxy) silane, β- (3 , 4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β- (aminoethyl) -Γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropylmethyldimethoxysilane, N, N-bis (β-hydroxyethyl) -γ-aminopropyltriethoxysilane, γ-chloropropyl Examples include trimethoxysilane. However, it is not limited to these.

  As the surface treatment method, any known method can be used, but a dry method or a wet method is preferably used.

  The amount of the silane coupling agent relative to the metal oxide particles in the undercoat layer 2 is arbitrarily set, but is preferably 0.5% by mass or more and 10% by mass or less with respect to the metal oxide particles.

-Electron-accepting compound In addition to metal oxide particles, an electron-accepting compound (acceptor compound) may be contained. Any electron accepting compound (acceptor compound) may be used. For example, quinone compounds such as chloranil and bromoanil, tetracyanoquinodimethane compounds, 2,4,7-trinitrofluorenone, 2, Fluorenone compounds such as 4,5,7-tetranitro-9-fluorenone, 2- (4-biphenyl) -5- (4-t-butylphenyl) -1,3,4-oxadiazole and 2,5-bis Oxadiazole compounds such as (4-naphthyl) -1,3,4-oxadiazole, 2,5-bis (4-diethylaminophenyl) 1,3,4-oxadiazole, xanthone compounds, thiophene compounds , Electron transporting materials such as diphenoquinone compounds such as 3,3 ′, 5,5 ′ tetra-t-butyldiphenoquinone are desirable. Compounds having Torakinon structure is desirable. Furthermore, acceptor compounds having an anthraquinone structure such as hydroxyanthraquinone compounds, aminoanthraquinone compounds, aminohydroxyanthraquinone compounds, and the like are desirably used.

The content of the electron-accepting compound in the undercoat layer 2 (including those present as solid content ratio / partial molecular weight) is preferably in the range of 0.004% by mass to 16% by mass. It is more desirable that the range be 02 mass% or more and 8 mass% or less.
Further, when the electron accepting compound is contained in the undercoat layer 2 in addition to the metal oxide particles, the electron accepting compound is desirably 0.01 parts by mass or more and 20 parts by mass with respect to 100 parts by mass of the metal oxide particles. It is used in an amount of not more than mass parts, more desirably in the range of not less than 0.05 parts by mass and not more than 10 parts by mass.

  The acceptor compound may be added only when the undercoat layer 2 is applied, or may be previously attached to the surface of the metal oxide particles. Examples of the method for imparting the acceptor compound to the surface of the metal oxide particles include a dry method or a wet method.

  When surface treatment is performed by a dry method, while stirring metal oxide particles with a mixer having a large shearing force or the like, an acceptor compound dissolved directly or in an organic solvent is dropped and sprayed with dry air or nitrogen gas. It is processed. The addition or spraying is preferably performed at a temperature below the boiling point of the solvent. After addition or spraying, baking may be performed at 100 ° C. or higher. About baking temperature and time, it implements in arbitrary ranges.

  As a wet method, the metal oxide particles are stirred in a solvent, dispersed using ultrasonic waves, a sand mill, an attritor, a ball mill, etc., and after adding or accepting an acceptor compound, the solvent is removed. The The solvent removal method is distilled off by filtration or distillation. After removing the solvent, baking may be performed at 100 ° C. or higher. About baking temperature and time, it implements in arbitrary ranges. In the wet method, the water containing metal oxide particles may be removed before adding the surface treatment agent. For example, the method of removing with stirring and heating in the solvent used for the surface treatment, removing by azeotroping with the solvent. You may use the method to do.

Other Additives Various additives may be used in the undercoat layer 2. As additives, known materials such as polycyclic condensation type, azo type electron transporting pigments, zirconium chelate compounds, titanium chelate compounds, aluminum chelate compounds, titanium alkoxide compounds, organic titanium compounds, silane coupling agents and the like are used. It is done.

  The silane coupling agent is used for the surface treatment of the metal oxide particles, but may be further added to the coating solution as an additive. Specific examples of the silane coupling agent used here include vinyltrimethoxysilane, γ-methacryloxypropyl-tris (β-methoxyethoxy) silane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ. -Glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, N-β -(Aminoethyl) -γ-aminopropylmethyldimethoxysilane, N, N-bis (β-hydroxyethyl) -γ-aminopropyltriethoxysilane, γ-chloropropyltrimethoxysilane and the like.

  Examples of zirconium chelate compounds include zirconium butoxide, zirconium zirconium acetoacetate, zirconium triethanolamine, acetylacetonate zirconium butoxide, ethyl zirconium acetoacetate, zirconium acetate, zirconium oxalate, zirconium lactate, zirconium phosphonate, zirconium octoate, naphthene. Zirconate, zirconium laurate, zirconium stearate, zirconium isostearate, methacrylate zirconium butoxide, stearate zirconium butoxide, isostearate zirconium butoxide and the like.

  Examples of titanium chelate compounds include tetraisopropyl titanate, tetranormal butyl titanate, butyl titanate dimer, tetra (2-ethylhexyl) titanate, titanium acetylacetonate, polytitanium acetylacetonate, titanium octylene glycolate, titanium lactate ammonium salt , Titanium lactate, titanium lactate ethyl ester, titanium triethanolamate, polyhydroxy titanium stearate and the like.

  Examples of the aluminum chelate compound include aluminum isopropylate, monobutoxy aluminum diisopropylate, aluminum butyrate, ethyl acetoacetate aluminum diisopropylate, aluminum tris (ethyl acetoacetate) and the like.

  These compounds may be used alone or as a mixture or polycondensate of a plurality of compounds.

-Formation of undercoat layer As a solvent for preparing a coating solution for forming the undercoat layer, known organic solvents such as alcohols, aromatics, halogenated hydrocarbons, ketones, ketone alcohols, ethers are used. , Selected from ester series and the like. Examples of the solvent include methanol, ethanol, n-propanol, iso-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, ethyl acetate, n-butyl acetate, Usual organic solvents such as dioxane, tetrahydrofuran, methylene chloride, chloroform, chlorobenzene and toluene are used.

  Moreover, you may use the solvent used for these dispersion | distribution individually or in mixture of 2 or more types. When mixing, any solvent can be used as long as it can dissolve the binder resin as the mixed solvent.

As a dispersion method, known methods such as a roll mill, a ball mill, a vibrating ball mill, an attritor, a sand mill, a colloid mill, and a paint shaker are used.
As the conditions for the above dispersion, for example, in dispersion by a sand mill using glass beads having a diameter of 1 mm, it is desirable to disperse at a filling rate of 70% to 95% and 0.1 hours to 100 hours.

  Further, as the coating method used when the undercoat layer 2 is provided, conventional methods such as blade coating method, wire bar coating method, spray coating method, dip coating method, bead coating method, air knife coating method, curtain coating method, etc. Is used.

  When the metal oxide particles and the electron-accepting compound are reacted, the coating film is formed even if the metal-oxide particles and the electron-accepting compound that reacts with the metal oxide particles react in the dispersion step. Although it may react during drying and hardening, it is desirable to react in a dispersion.

By using the undercoat layer forming coating solution thus obtained, the undercoat layer forming coating solution coated on the support 1 is dried to form the undercoat layer 2.
The drying conditions are usually carried out at a temperature at which the solvent can be evaporated to form a film. For example, the temperature is preferably 150 ° C. or higher and 200 ° C. or lower, more preferably 160 ° C. or higher and 200 ° C. or lower, and 170 ° C. or higher and 190 ° C. or lower. More preferably, it is not higher than ° C. Moreover, as drying time, 10 minutes or more and 50 minutes or less are preferable, and 20 minutes or more and 40 minutes or less are more preferable.

-Physical properties of the undercoat layer The undercoat layer 2 preferably has a resistance value of 1 × 10 ⁸ Ω or more and 1 × 10 ¹⁰ Ω or less, more preferably 1 × 10 ⁹ Ω or more and 1 × 10 ¹⁰ Ω in AC impedance measurement. The following is more preferable.

The detailed method for measuring the resistance value of the undercoat layer 2 is as follows.
First, the impedance of the undercoat layer 2 is measured. Using a support such as an aluminum pipe in the impedance measurement sample as a cathode and a gold electrode as an anode, an AC voltage of 1 Vp-p is applied from the high frequency side in a frequency range from 1 MHz to 1 mHz, and the AC impedance of each sample is measured. The resistance value of the undercoat layer 2 is obtained by fitting the Cole-Cole plot graph obtained from this measurement to an RC parallel equivalent circuit.

  A method for preparing an undercoat layer sample for resistance value measurement from an electrophotographic photosensitive member is as follows. For example, a coating such as a charge generation layer and a charge transport layer covering the undercoat layer is removed using a solvent such as acetone, tetrahydrofuran, methanol, ethanol, etc., and a vacuum deposition method or the like is applied to the exposed undercoat layer. By attaching a gold electrode by sputtering or the like, an undercoat layer sample for volume resistivity measurement is obtained.

Examples of the method for adjusting the resistance value of the undercoat layer 2 within the above range include adjusting the addition amount and particle diameter of the metal oxide particles, or metal oxide particles in the undercoat layer forming coating solution. Or a method of changing the dispersion method. As the particle size of the metal oxide particles increases, the resistance value of the undercoat layer tends to decrease. Moreover, the resistance value of the undercoat layer tends to increase as the amount of the metal oxide particles added increases. Furthermore, when the dispersibility of the metal oxide particles in the coating solution for forming the undercoat layer is improved, the resistance value of the undercoat layer tends to increase. Specifically, the resistance value of the undercoat layer tends to increase as the dispersion treatment time of the coating solution for forming the undercoat layer is increased.
Furthermore, the resistance value of the undercoat layer is also adjusted by the drying temperature at the time of forming the undercoat layer, and the resistance value of the undercoat layer tends to decrease as the drying temperature increases.

  The undercoat layer 2 may be set to any thickness, but in particular, from the viewpoint of controlling the resistance value of the undercoat layer within the above range, the thickness is preferably 15 μm or more, and more preferably 15 μm or more and 50 μm or less. .

  The undercoat layer 2 preferably has a Vickers strength of 35 or more.

Further, the surface roughness (ten-point average roughness) of the undercoat layer 2 is from 1 / 4n (n is the refractive index of the upper layer) to 1 / 2λ of the exposure laser wavelength λ used to prevent moire images. It is desirable to be adjusted to.
In order to adjust the surface roughness, particles such as a resin may be added to the undercoat layer. As the resin particles, silicone resin particles, cross-linked polymethyl methacrylate resin particles and the like are used. Further, the undercoat layer may be polished for adjusting the surface roughness. As a polishing method, buffing, sandblasting, wet honing, grinding, or the like is used.

(Middle layer)
An intermediate layer 4 may be provided between the undercoat layer and the photosensitive layer.
The material constituting the intermediate layer 4 includes acetal resin such as polyvinyl butyral, polyvinyl alcohol resin, casein, polyamide resin, cellulose resin, gelatin, polyurethane resin, polyester resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinyl acetate. In addition to polymer resin compounds such as resin, vinyl chloride-vinyl acetate-maleic anhydride resin, silicone resin, silicone-alkyd resin, phenol-formaldehyde resin, melamine resin, zirconium, titanium, aluminum, manganese, silicon atoms, etc. Contains organometallic compounds.
These compounds may be used alone or as a mixture or polycondensate of a plurality of compounds. Of these, organometallic compounds containing zirconium or silicon are desirable.

  Examples of the silicon compound include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (β-methoxyethoxysilane), γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyl-tris (β-methoxyethoxy) silane, β -(3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β- ( Aminoethyl) -γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropylmethyldimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, N, N-bis (β-hydroxy) ethyl) -Γ-aminopropyltriethoxysilane, γ-chloropropyltrimethoxysilane, and the like. Among these, particularly preferably used silicon compounds are vinyltriethoxysilane, vinyltris (β-methoxyethoxysilane), γ-methacryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, β- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane, N-β- (aminoethyl) γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) γ-aminopropylmethyldimethoxysilane, γ-aminopropyltriethoxysilane, Examples include silane coupling agents such as N-phenyl-γ-aminopropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, and γ-chloropropyltrimethoxysilane.

  Examples of organic zirconium compounds include zirconium butoxide, zirconium zirconium acetoacetate, zirconium triethanolamine, acetylacetonate zirconium butoxide, ethyl acetoacetate butoxide, zirconium acetate, zirconium oxalate, zirconium lactate, zirconium phosphonate, zirconium octoate, naphthene. Zirconate, zirconium laurate, zirconium stearate, zirconium isostearate, methacrylate zirconium butoxide, stearate zirconium butoxide, isostearate zirconium butoxide and the like.

  Examples of organic titanium compounds include tetraisopropyl titanate, tetranormal butyl titanate, butyl titanate dimer, tetra (2-ethylhexyl) titanate, titanium acetylacetonate, polytitanium acetylacetonate, titanium octylene glycolate, titanium lactate ammonium salt , Titanium lactate, titanium lactate ethyl ester, titanium triethanolamate, polyhydroxy titanium stearate and the like.

  Examples of the organoaluminum compound include aluminum isopropylate, monobutoxyaluminum diisopropylate, aluminum butyrate, diethyl acetoacetate aluminum diisopropylate, and aluminum tris (ethyl acetoacetate).

  In addition, as a coating method used when providing the intermediate layer, a normal method such as a blade coating method, a wire bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method, or a curtain coating method is used. It is done.

  When the intermediate layer 4 is formed, it is desirable to set the film thickness within the range of 0.1 μm to 3 μm.

(Charge generation layer)
The charge generation layer 31 of the photosensitive layer is formed by vacuum-depositing a charge generation material, or by dispersing and applying the charge generation material together with an organic solvent, a binder resin, an additive, and the like.
In this embodiment, a known charge generation material may be used as the charge generation material, but particularly excellent performance is obtained, and a phthalocyanine pigment is preferably used as the charge generation material. In addition, these organic pigments generally have several crystal forms, and any of these crystal forms may be used as long as it is a pigment capable of obtaining a sensitivity suitable for the purpose. Specific examples of charge generation materials that are particularly preferably used are shown below.

Examples of the charge generation material include phthalocyanine pigments such as metal-free phthalocyanine, chlorogallium phthalocyanine, hydroxygallium phthalocyanine, dichlorotin phthalocyanine, and titanyl phthalocyanine. Chlorogallium phthalocyanine crystal having strong diffraction peaks at least at 7.4 °, 16.6 °, 25.5 ° and 28.3 °, Bragg angle (2θ ± 0.2 °) to CuKα characteristic X-ray of at least 7. Metal-free phthalocyanine crystals having strong diffraction peaks at 7 °, 9.3 °, 16.9 °, 17.5 °, 22.4 ° and 28.8 °, Bragg angle (2θ ± 0. 2 °) at least 7.5 °, 9.9 °, 12.5 °, 16.3 °, 18.6 °, Hydroxygallium phthalocyanine crystals with strong diffraction peaks at 5.1 ° and 28.3 °, Bragg angles (2θ ± 0.2 °) to CuKα characteristic X-rays of at least 9.6 °, 24.1 ° and 27.2 A titanyl phthalocyanine crystal having a strong diffraction peak at a temperature of at least 7.6 °, 18.3 °, 23.2 °, 24.2 °, and 27. of a Bragg angle (2θ ± 0.2 °) with respect to CuKα characteristic X-rays. Examples thereof include titanyl phthalocyanine crystals having a strong diffraction peak at 3 °. In addition, examples of the charge generation material include quinone pigments, perylene pigments, indigo pigments, bisbenzimidazole pigments, anthrone pigments, quinacridone pigments, and the like. These charge generation materials may be used alone or in combination of two or more.
Among these, at least 7.5 °, 9.9 °, 12.5 °, 16.3 °, 18.6 °, 25.1 ° of the Bragg angle (2θ ± 0.2 °) with respect to CuKα characteristic X-rays. And a hydroxygallium phthalocyanine crystal having a strong diffraction peak at 28.3 °, a Bragg angle (2θ ± 0.2 °) of CuKα characteristic X-ray of at least 7.6 °, 18.3 °, 23.2 °, 24. A titanyl phthalocyanine crystal having strong diffraction peaks at 2 ° and 27.3 ° is preferable.

The charge generation material used in the present embodiment is, for example, mechanically dry pulverizing pigment crystals produced by a known method using an automatic mortar, planetary mill, vibration mill, CF mill, roller mill, sand mill, kneader, or the like. After the dry pulverization, it is manufactured by performing a wet pulverization process using a ball mill, a mortar, a sand mill, a kneader or the like together with a solvent. Solvents used in the above treatment are aromatics (toluene, chlorobenzene, etc.), amides (dimethylformamide, N-methylpyrrolidone, etc.), aliphatic alcohols (methanol, ethanol, butanol, etc.), aliphatic polyvalents. Alcohols (ethylene glycol, glycerin, polyethylene glycol, etc.), aromatic alcohols (benzyl alcohol, phenethyl alcohol, etc.), esters (acetic ester, butyl acetate, etc.), ketones (acetone, methyl ethyl ketone, etc.), dimethyl sulfoxide, ether (Diethyl ether, tetrahydrofuran, etc.), several mixed systems, and mixed systems of water and these organic solvents.
The solvent is used in a range (mass ratio) of 1 part to 200 parts, preferably 10 parts to 100 parts, based on the pigment crystals.
The treatment temperature is 0 ° C. or higher and the boiling point of the solvent or lower, preferably 10 ° C. or higher and 60 ° C. or lower.

Further, grinding aids such as sodium chloride and sodium nitrate are used during grinding. The grinding aid may be used 0.5 to 20 times, preferably 1 to 10 times the pigment.
Further, the pigment crystal produced by a known method is controlled by combining acid pasting or acid pasting and the above-described dry pulverization or wet pulverization. The acid used for acid pasting is preferably sulfuric acid, having a concentration of 70% to 100%, preferably 95% to 100%, and a dissolution temperature of −20 ° C. to 100 ° C., preferably 0 It is set in the range of not less than 60 ° C and not more than 60 ° C. The amount of concentrated sulfuric acid is set in the range of 1 to 100 times, preferably 3 to 50 times the mass of the pigment crystal. As a solvent to be precipitated, water or a mixed solvent of water and an organic solvent is used in an arbitrary amount. The temperature for precipitation is not particularly limited, but it is desirable to cool with ice or the like in order to prevent heat generation.

The binder resin used for the charge generation layer is selected from a wide range of insulating resins. You may select from organic photoconductive polymers, such as poly-N-vinyl carbazole, polyvinyl anthracene, polyvinyl pyrene, polysilane.
Desirable binder resins include polyvinyl acetal resin, polyarylate resin (polycondensate of bisphenol A and phthalic acid, etc.), polycarbonate resin, polyester resin, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyamide resin, acrylic resin. Insulating resins such as polyacrylamide resin, polyvinyl pyridine resin, cellulose resin, urethane resin, epoxy resin, casein, polyvinyl alcohol resin, polyvinyl pyrrolidone resin are not limited thereto. These binder resins may be used alone or in combination of two or more. Of these, polyvinyl acetal resin is particularly preferably used.
In addition, the blending ratio (mass ratio) of the charge generation material and the binder resin is preferably in the range of 10: 1 to 1:10.

The solvent for adjusting the coating solution may be selected from known organic solvents such as alcohols, aromatics, halogenated hydrocarbons, ketones, ketone alcohols, ethers and esters. For example, methanol, ethanol, n-propanol, iso-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, ethyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, Usual organic solvents such as methylene chloride, chloroform, chlorobenzene and toluene are used.
You may use the solvent used for dispersion | distribution individually or in mixture of 2 or more types. When mixing, any solvent may be used as long as it dissolves the binder resin as a mixed solvent.

As a dispersion method, methods such as a roll mill, a ball mill, a vibration ball mill, an attritor, a sand mill, a colloid mill, and a paint shaker are used.
When dispersing, it is effective that the particles have a particle size of 0.5 μm or less, desirably 0.3 μm or less, and more desirably 0.15 μm or less.

  Various additives may be added to the coating solution for forming the charge generation layer. Additives include quinone compounds such as chloranil, bromoanil and anthraquinone, tetracyanoquinodimethane compounds, fluorenones such as 2,4,7-trinitrofluorenone and 2,4,5,7-tetranitro-9-fluorenone Compounds, 2- (4-biphenyl) -5- (4-t-butylphenyl) -1,3,4-oxadiazole and 2,5-bis (4-naphthyl) -1,3,4-oxadi Azoles, oxadiazole compounds such as 2,5-bis (4-diethylaminophenyl) 1,3,4 oxadiazole, xanthone compounds, thiophene compounds, 3,3 ′, 5,5 ′ tetra-t-butyl Electron transporting substances such as diphenoquinone compounds such as diphenoquinone, electron transporting pigments such as polycyclic condensation systems and azo systems, zirconium chelate compounds, tita Umukireto compounds, aluminum chelate compounds, titanium alkoxide compounds, organic titanium compounds, known materials such as a silane coupling agent is used.

  Examples of silane coupling agents include vinyltrimethoxysilane, γ-methacryloxypropyl-tris (β-methoxyethoxy) silane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltri Methoxysilane, vinyltriacetoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, N-β- (aminoethyl)- γ-aminopropylmethyldimethoxysilane, N, N-bis (β-hydroxyethyl) -γ-aminopropyltriethoxysilane, γ-chloropropyltrimethoxysilane, and the like.

  Examples of zirconium chelate compounds include zirconium butoxide, zirconium zirconium acetoacetate, zirconium triethanolamine, acetylacetonate zirconium butoxide, ethyl acetoacetate butoxide, zirconium acetate, zirconium oxalate, zirconium lactate, zirconium phosphonate, zirconium octoate, naphthene. Zirconate, zirconium laurate, zirconium stearate, zirconium isostearate, methacrylate zirconium butoxide, stearate zirconium butoxide, isostearate zirconium butoxide and the like.

  Examples of titanium chelate compounds include tetraisopropyl titanate, tetranormal butyl titanate, butyl titanate dimer, tetra (2-ethylhexyl) titanate, titanium acetylacetonate, polytitanium acetylacetonate, titanium octylene glycolate, titanium lactate ammonium salt , Titanium lactate, titanium lactate ethyl ester, titanium triethanolamate, polyhydroxy titanium stearate and the like.

Examples of the aluminum chelate compound include aluminum isopropylate, monobutoxy aluminum diisopropylate, aluminum butyrate, diethyl acetoacetate aluminum diisopropylate, aluminum tris (ethyl acetoacetate) and the like.
These compounds are used alone or as a mixture or polycondensate of a plurality of compounds.

As a coating method used when providing the charge generation layer, a usual method such as a blade coating method, a wire bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method, a curtain coating method, or the like is used. .
The thickness of the charge generation layer is desirably set in the range of 0.01 μm to 5 μm, more desirably 0.05 μm to 2.0 μm.

(Charge transport layer)
As a charge transport material contained in the charge transport layer, any known material may be used, but the following are exemplified. Oxadiazole derivatives such as 2,5-bis (p-diethylaminophenyl) -1,3,4-oxadiazole, 1,3,5-triphenyl-pyrazoline, 1- [pyridyl- (2)]-3 Pyrazoline derivatives such as-(p-diethylaminostyryl) -5- (p-diethylaminostyryl) pyrazoline, triphenylamine, tri (P-methyl) phenylamine, N, N'-bis (3,4-dimethylphenyl) biphenyl Aromatic tertiary amino compounds such as -4-amine, dibenzylaniline, 9,9-dimethyl-N, N′-di (p-tolyl) fluoren-2-amine, N, N′-diphenyl-N, Aromatic tertiary diamino compounds such as N′-bis (3-methylphenyl)-[1,1-biphenyl] -4,4′-diamine, 3- (4′dimethylaminophen L) -5,6-di- (4′-methoxyphenyl) -1,2,4-triazine, 1,2,4-triazine derivatives, 4-diethylaminobenzaldehyde-1,1-diphenylhydrazone, 4-diphenyl Hydrazone derivatives such as aminobenzaldehyde-1,1-diphenylhydrazone, [p- (diethylamino) phenyl] (1-naphthyl) phenylhydrazone, quinazoline derivatives such as 2-phenyl-4-styryl-quinazoline, 6-hydroxy-2, Benzofuran derivatives such as 3-di (p-methoxyphenyl) -benzofuran, α-stilbene derivatives such as p- (2,2-diphenylvinyl) -N, N′-diphenylaniline, enamine derivatives, N-ethylcarbazole, etc. Carbazole derivatives, poly-N-vinylcarbazole and Hole transport materials such as derivatives thereof, quinone compounds such as chloranil, bromoanil and anthraquinone, tetracyanoquinodimethane compounds, 2,4,7-trinitrofluorenone, 2,4,5,7-tetranitro-9- Fluorenone compounds such as fluorenone, 2- (4-biphenyl) -5- (4-t-butylphenyl) -1,3,4-oxadiazole and 2,5-bis (4-naphthyl) -1,3 Oxadiazole compounds such as 4-oxadiazole, 2,5-bis (4-diethylaminophenyl) 1,3,4 oxadiazole, xanthone compounds, thiophene compounds, 3,3 ′, 5,5′tetra -A group derived from an electron transporting material such as a diphenoquinone compound such as t-butyldiphenoquinone or a compound derived from the above-described compounds is present in the main chain or side chain. And the like. These charge transport materials are used alone or in combination of two or more.

  As the binder resin for the charge transport layer, known resins may be used. For example, polycarbonate resin, polyester resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinylidene chloride resin, polystyrene resin, polyvinyl acetate resin, styrene -Butadiene copolymer, vinylidene chloride-acrylonitrile copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicone resin. Silicon-alkyd resin, phenol-formaldehyde resin, styrene-alkyd resin, poly-N-carbazole, polyvinyl butyral, polyvinyl formal, polysulfone, casein, gelatin, polyvinyl alcohol, ethyl cellulose, phenol resin, polyamide, carboxy-methyl cellulose, vinylidene chloride Examples thereof include, but are not limited to, polymer wax and polyurethane.

These binder resins may be used alone or in combination of two or more, and in particular, polycarbonate resins, polyester resins, methacrylic resins, and acrylic resins are preferably used.
The blending ratio (mass ratio) of the binder resin and the charge transport material is preferably 10: 1 to 1: 5.

The thickness of the charge transport layer is preferably 5 μm or more and 50 μm or less, and more preferably 10 μm or more and 35 μm or less.
As a coating method used when the charge transport layer is provided, usual methods such as a blade coating method, a wire bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method, and a curtain coating method are used. . Solvents used for coating include aromatic hydrocarbons such as benzene, toluene, xylene and chlorobenzene, ketones such as acetone and 2-butanone, and halogenated aliphatic hydrocarbons such as methylene chloride, chloroform and ethylene chloride, Usual organic solvents such as cyclic or linear ethers such as tetrahydrofuran and ethyl ether are used singly or in admixture of two or more.

Furthermore, an additive such as an antioxidant, a light stabilizer, and a heat stabilizer may be added to the photosensitive layer in the electrophotographic photoreceptor of this embodiment.
Examples of the antioxidant include hindered phenol, hindered amine, paraphenylenediamine, arylalkane, hydroquinone, spirochroman, spiroidanone and their derivatives, organic sulfur compounds, and organic phosphorus compounds.

Specific examples of antioxidants include phenolic antioxidants such as 2,6-di-t-butyl-4-methylphenol, styrenated phenol, n-octadecyl-3- (3 ′, 5′-di -T-butyl-4'-hydroxyphenyl) -propionate, 2,2'-methylene-bis- (4-methyl-6-t-butylphenol), 2-t-butyl-6- (3'-t-butyl) -5'-methyl-2'-hydroxybenzyl) -4-methylphenyl acrylate, 4,4'-butylidene-bis- (3-methyl-6-tert-butyl-phenol), 4,4'-thio-bis -(3-methyl-6-tert-butylphenol), 1,3,5-tris (4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl) isocyanurate, tetrakis- [methylene-3- (3 ', 5' Di-tert-butyl-4′-hydroxy-phenyl) propionate] -methane, 3,9-bis [2- [3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy] -1 , 1-dimethylethyl] -2,4,8,10-tetraoxaspiro [5,5] undecane. Among hindered amine compounds, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, 1- [2- [3 -(3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy] ethyl] -4- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy] -2, 2,6,6-tetramethylpiperidine, 8-benzyl-7,7,9,9-tetramethyl-3-octyl-1,3,8-triazaspiro [4,5] undecane-2,4-dione, 4, -Benzoyloxy-2,2,6,6-tetramethylpiperidine, dimethyl-1- (2-hydroxyethyl) -4-hydroxy-2,2,6,6-tetramethylpiperidine heavy succinate Compound, poly [{6- (1,1,3,3-tetramethylbutyl) imino-1,3,5-triazine-2,4-diimyl} {(2,2,6,6-tetramethyl- 4-piperidyl) imino} hexamethylene {(2,3,6,6-tetramethyl-4-piperidyl) imino}], 2- (3,5-di-t-butyl-4-hydroxybenzyl) -2- n-Butylmalonate bis (1,2,2,6,6-pentamethyl-4-piperidyl), N, N′-bis (3-aminopropyl) ethylenediamine-2,4-bis [N-butyl-N— (1,2,2,6,6, -pentamethyl-4piperidyl) amino] -6-chloro-1,3,5-triazine condensate and the like. Dilauryl-3,3′-thiodipropionate, dimyristyl-3,3′-thiodipropionate, distearyl-3,3′-thiodipropionate, pentaerythritol-tetrakis- ( β-lauryl-thiopropionate), ditridecyl-3,3′-thiodipropionate, 2-mercaptobenzimidazole and the like. Examples of the organophosphorus antioxidant include trisnonylphenyl phosfte, triphenyl phosfte, tris (2,4-di-t-butylphenyl) -phosfte, and the like.
Organic sulfur-based and organic phosphorus-based antioxidants are referred to as secondary antioxidants, and a synergistic effect is obtained by using them together with primary antioxidants such as phenolic or amine-based antioxidants.

Examples of the light stabilizer include benzophenone, benzotriazole, dithiocarbamate, and tetramethylpiperidine derivatives.
Examples of the benzophenone light stabilizer include 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, and 2,2′-di-hydroxy-4-methoxybenzophenone. As a benzotriazole-based light stabilizer, 2-(-2′-hydroxy-5′methylphenyl-)-benzotriazole, 2- [2′-hydroxy-3 ′-(3 ″, 4 ″, 5 ″) , 6 ″ -tetra-hydrophthalimido-methyl) -5′-methylphenyl] -benzotriazole, 2-(-2′-hydroxy-3′-t-butyl-5′-methylphenyl-)-5-chloro Benzotriazole, 2- (2′-hydroxy-3′-t-butyl-5′-methylphenyl-)-5-chlorobenzotriazole, 2- (2′-hydroxy-3 ′, 5′-t-butylphenyl) -)-Benzotriazole, 2- (2'-hydroxy-5'-t-octylphenyl) -benzotriazole, 2- (2'-hydroxy-3 ', 5'-di-t-amylphenyl-)-benzo Triazole etc. are mentioned Other compounds include 2,4, di-t-butylphenyl-3 ′, 5′-di-t-butyl-4′-hydroxybenzoate, nickel dibutyl-dithiocarbamate, and the like.

Further, at least one kind of electron accepting substance may be contained. Examples of the electron-accepting substance used in the photoconductor of this embodiment include succinic anhydride, maleic anhydride, dibromomaleic anhydride, phthalic anhydride, tetrabromophthalic anhydride, tetracyanoethylene, tetracyanoquinodimethane, Examples include o-dinitrobenzene, m-dinitrobenzene, chloranil, dinitroanthraquinone, trinitrofluorenone, picric acid, o-nitrobenzoic acid, p-nitrobenzoic acid, and phthalic acid. Of these, fluorenone-based, quinone-based, and benzene derivatives having electron-withdrawing substituents such as Cl, CN, NO ₂ are particularly preferable.

  Moreover, you may add a silicone oil as a leveling agent to a coating liquid.

(Protective layer)
In the electrophotographic photoreceptor of this embodiment, the protective layer 5 may be provided on the photosensitive layer. This protective layer is provided to prevent chemical change of the charge transport layer during charging or to further improve the mechanical strength of the photosensitive layer in a photoreceptor having a laminated structure. A known protective layer is used as the protective layer.

The thickness of the protective layer is preferably 1 μm or more and 20 μm or less, and more preferably 2 μm or more and 10 μm or less.
As a coating method used when the protective layer is provided, usual methods such as a blade coating method, a wire bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method, and a curtain coating method are used.
As a solvent used for coating, ordinary organic solvents such as dioxane, tetrahydrofuran, methylene chloride, chloroform, chlorobenzene, toluene and the like may be used singly or as a mixture of two or more, but a solvent which does not dissolve the lower layer is used. desirable.

The photoconductor according to the present embodiment is suitably used for an image forming apparatus such as a laser beam printer, a digital copying machine, an LED printer, or a laser facsimile that emits near-infrared light or visible light.
The photoreceptor according to the exemplary embodiment is used in combination with a one-component or two-component regular developer or reversal developer.

<Image forming apparatus>
Next, the image forming apparatus of this embodiment will be described.
FIG. 7 is a schematic configuration diagram illustrating an example of the image forming apparatus according to the present exemplary embodiment. The image forming apparatus 100 shown in FIG. 7 includes the drum-shaped (cylindrical) electrophotographic photosensitive member 7 of the present embodiment provided so as to be rotatable. Around the electrophotographic photoreceptor 7, along the movement direction of the outer peripheral surface of the electrophotographic photoreceptor 7, a charging device 8, an exposure device 10, a developing device 11, a transfer device 12, a cleaning device 13, and a charge eliminating device (erase device). 14) are arranged in this order.
In addition, it is good also as an aspect which does not have the static elimination apparatus 14 from a viewpoint of cost reduction.

Charging device The charging device 8 is a corona charging type charging device and charges the electrophotographic photosensitive member 7. The charging device 8 is connected to a power source 9. Examples of the charging device 8 include a non-contact type roller charger, a scorotron charger using corona discharge, and a corotron charger.

Further, for example, a well-known charger such as a contact charger using a conductive charging roller, a charging brush, a charging film, a charging rubber blade, a charging tube or the like may be used.
Here, FIG. 8 is a schematic view showing an example of a contact charging type image forming apparatus using the electrophotographic photosensitive member of the present embodiment.
The contact charging member is disposed so as to be in contact with the surface of the photoconductor, and applies a voltage directly to the photoconductor to charge the surface of the photoconductor to a predetermined potential. This contact charging member includes metals such as aluminum, iron and copper, conductive polymer materials such as polyacetylene, polypyrrole and polythiophene, polyurethane rubber, silicone rubber, epichlorohydrin rubber, ethylene propylene rubber, acrylic rubber, fluorine rubber, styrene A material obtained by dispersing metal oxide particles such as carbon black, copper iodide, silver iodide, zinc sulfide, silicon carbide, and metal oxide in an elastomer material such as butadiene rubber or butadiene rubber is used.

Examples of the metal oxide used for the contact charging member include Z ₂ O, SnO ₂ , TiO ₂ , In ₂ O ₃ , MoO ₃ , or a composite oxide thereof. Moreover, perchlorate may be included in the elastomer material to impart conductivity.

Furthermore, a coating layer may be provided on the surface. As a material for forming this coating layer, N-alkoxymethylated nylon, cellulose resin, vinyl pyridine resin, phenol resin, polyurethane, polyvinyl butyral, melamine and the like are used alone or in combination.
Further, an emulsion resin material, for example, an acrylic resin emulsion, a polyester resin emulsion, a polyurethane, particularly an emulsion resin synthesized by soap-free emulsion polymerization may be used. In these resins, in order to further adjust the resistivity, conductive agent particles may be dispersed or an antioxidant may be contained. Further, the emulsion resin may contain a leveling agent or a surfactant.

Examples of the shape of the contact charging member include a roller type, a blade type, a belt type, and a brush type. The resistance of the contact charging member is desirably 10 ² Ωcm or more and 10 ¹² Ωcm or less, more desirably 10 ³ Ωcm or more and 10 ⁸ Ωcm or less. The voltage applied to the contact charging member may be applied in the form of direct current or direct current + alternating current.

Exposure Device The exposure device 10 exposes the charged electrophotographic photosensitive member 7 to form an electrostatic latent image on the electrophotographic photosensitive member 7. Examples of the exposure apparatus 10 include optical system devices that expose the surface of the electrophotographic photoreceptor 7 with light such as semiconductor laser light, LED light, and liquid crystal shutter light imagewise. The wavelength of the light source is preferably in the spectral sensitivity region of the electrophotographic photoreceptor 7. The wavelength of the semiconductor laser is preferably, for example, near infrared having an oscillation wavelength of around 780 nm, but is not limited to this wavelength, and a laser having an oscillation wavelength in the range of 600 nm or a blue laser having an oscillation wavelength of 400 nm to 450 nm. May also be used. Further, as the exposure apparatus 10, for example, a surface emitting laser light source of a multi-beam output type is also effective for color image formation.

Developing device The developing device 11 develops the electrostatic latent image with a developer to form a toner image. The developer preferably contains toner particles having a volume average particle diameter of 3 μm or more and 9 μm or less obtained by a polymerization method. An example of the developing device 11 is a configuration in which a developing roll disposed in the developing region facing the electrophotographic photosensitive member 7 is provided in a container that contains a two-component developer composed of toner and carrier.

Transfer Device The transfer device 12 transfers the toner image developed on the electrophotographic photosensitive member 7 to a transfer medium. Examples of the transfer device 12 include known transfer chargers such as a contact transfer charger using a belt, a roller, a film, a rubber blade, a scorotron transfer charger using a corona discharge, and a corotron transfer charger. Can be mentioned.

Cleaning device The cleaning device 13 removes toner remaining on the electrophotographic photosensitive member 7 after transfer. The cleaning device 13 preferably has a blade member that contacts the electrophotographic photoreceptor 7 at a linear pressure of 10 g / cm to 150 g / cm. The cleaning device 13 includes, for example, a housing, a cleaning blade, and a cleaning brush disposed on the downstream side of the cleaning blade in the rotation direction of the electrophotographic photosensitive member 7. In addition, for example, a solid lubricant is disposed in contact with the cleaning brush.

-Neutralizing Device The neutralizing device (erasing device) 14 irradiates the surface of the electrophotographic photosensitive member 7 after transferring the toner image with static eliminating light to neutralize the potential remaining on the surface of the electrophotographic photosensitive member. For example, the static eliminator 14 irradiates static electricity over the entire width in the axial direction of the electrophotographic photosensitive member 7, and determines the potential difference between the exposed portion and the non-exposed portion by the exposure device 10 generated on the surface of the electrophotographic photosensitive member 7. Remove. In addition, the aspect in which the static elimination apparatus 14 is not provided may be sufficient.

Fixing Device The image forming apparatus 100 includes a fixing device 15 that fixes the toner image on the transfer medium after the transfer process. The fixing device is not particularly limited, and examples thereof include known fixing devices such as a heat roller fixing device and an oven fixing device.

Next, operations of the image forming apparatuses 100 and 101 according to the present embodiment will be described. First, the electrophotographic photosensitive member 7 rotates along the direction indicated by the arrow A and is negatively charged by the charging device 8. The electrophotographic photosensitive member 7 whose surface is negatively charged by the charging device 8 is exposed by the exposure device 10 to form an electrostatic latent image on the surface.
When the portion where the electrostatic latent image is formed on the electrophotographic photosensitive member 7 approaches the developing device 11, the developing device 11 attaches toner to the electrostatic latent image and forms a toner image.
When the electrophotographic photosensitive member 7 on which the toner image is formed further rotates in the direction of arrow A, the toner image is transferred onto the recording paper P by the transfer device 12. As a result, a toner image is formed on the recording paper P.
The toner image is fixed on the recording paper P on which the image is formed by the fixing device 15.

<Process cartridge>
For example, the image forming apparatus according to the present embodiment may be configured such that a process cartridge including the electrophotographic photosensitive member 7 according to the present embodiment described above is attached to and detached from the image forming apparatus.
The configuration of the process cartridge according to the present embodiment may be at least provided with the electrophotographic photosensitive member 7 according to the present embodiment. In addition to the electrophotographic photosensitive member 7, for example, a charging device 8, an exposure device 10, and the like. You may provide the at least 1 component selected from the image development apparatus 11, the transfer apparatus 12, the cleaning apparatus 13, and the static elimination apparatus 14. FIG.

  In addition, the image forming apparatus according to the present embodiment is not limited to the above-described configuration, and a known configuration, for example, an intermediate for transferring the toner image formed on the electrophotographic photosensitive member 7 to the intermediate transfer member and then transferring the toner image to the recording paper P. A transfer type image forming apparatus may be employed, or a tandem type image forming apparatus may be employed.

  EXAMPLES Hereinafter, although this invention is demonstrated further more concretely based on an Example and a comparative example, this invention is not limited to a following example at all. In the following description, “part” means “part by mass” unless otherwise specified.

<Example 1>
-Production of photoconductor-
Undercoat layer 100 parts of zinc oxide (average particle size: 70 nm, manufactured by Teika, specific surface area value: 15 m ² / g) is stirred and mixed with 500 parts of methanol, and KBM603 (manufactured by Shin-Etsu Chemical Co., Ltd.) 0 as a silane coupling agent .75 parts was added and stirred for 2 hours. Thereafter, methanol was distilled off under reduced pressure, and baking was performed at 120 ° C. for 3 hours to obtain silane coupling agent surface-treated zinc oxide particles.

60 parts of the surface-treated zinc oxide particles, 0.6 parts of alizarin, 13.5 parts of blocked isocyanate (Sumidule 3173, manufactured by Sumitomo Bayern Urethane Co., Ltd.) as a curing agent, and butyral resin (BM-1, Sekisui Chemical) 38 parts of a solution prepared by dissolving 15 parts of methyl ethyl ketone in 85 parts of methyl ethyl ketone and 25 parts of methyl ethyl ketone were mixed and dispersed in a sand mill for 4 hours using glass beads having a diameter of 1 mm to obtain a dispersion. As a catalyst, 0.005 part of dioctyltin dilaurate and 4.0 parts of silicone resin particles (Tospearl 145, manufactured by GE Toshiba Silicone) are added to the resulting dispersion to obtain a coating solution for forming an undercoat layer. It was.
This coating solution was applied on an aluminum support having a diameter of 30 mm by a dip coating method, followed by drying and curing at 176 ° C. for 24 minutes to obtain an undercoat layer having a thickness of 32 μm.

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

Charge transport layer Next, 8 parts of tetrafluoroethylene resin particles (average particle size: 0.2 μm) and 0.01 part of a fluorinated alkyl group-containing methacrylic copolymer (weight average molecular weight 30000) were added to 4 parts of tetrahydrofuran and 1 toluene. The mixture was kept at a liquid temperature of 20 ° C. together with the part and stirred and mixed for 48 hours to obtain a tetrafluoroethylene resin particle suspension A.
Next, 4 parts of tris [4- (4,4-diphenyl-1,3-butadienyl) phenyl] amine as a charge transport material and bisphenol Z type polycarbonate resin (viscosity average molecular weight: 40,000) as a binder resin are used. 6 parts, 0.1 part of 2,6-di-t-butyl-4-methylphenol as an antioxidant was mixed and 24 parts of tetrahydrofuran and 11 parts of toluene were mixed and dissolved to obtain a mixed solution B . After adding the resin particle suspension A to the mixed solution B and stirring and mixing, 500 kgf / cm using a high-pressure homogenizer (manufactured by Yoshida Kikai Kogyo Co., Ltd.) equipped with a through-type chamber having a fine flow path. 5 ppm of fluorine-modified silicone oil (trade name: FL-100, manufactured by Shin-Etsu Silicone Co., Ltd.) was added to the liquid obtained by increasing the pressure to ² and repeating the dispersion treatment 6 times, and stirred to obtain a coating liquid for forming a charge transport layer. .
This charge transport layer forming coating solution was applied onto the charge generation layer and dried at 135 ° C. for 25 minutes to form a charge transport layer having a thickness of 24 μm.

-Vacuum drying treatment Next, the obtained electrophotographic photosensitive member was vacuum dried using a drying apparatus (trade name DRV422DB, manufactured by ADVANTEC) at 80 ° C. for 3 hours to obtain an electrophotographic photosensitive member. .

<Examples 2-5, Comparative Examples 1-2>
In Example 1, the temperature at the time of drying and curing at the time of forming the undercoat layer was changed from 176 ° C. to the temperature described in Table 1 below, and the drying conditions at the time of vacuum drying treatment were described from 80 ° C. for 3 hours to Table 1 below. A photoconductor was prepared by the method described in Example 1 except that the conditions were changed.

〔Evaluation test〕
-Mass change-
In accordance with the method for forming the undercoat layer in the examples and comparative examples, only the undercoat layer is formed on the aluminum substrate, and then the vacuum drying described in Table 1 is performed on the aluminum substrate having the undercoat layer. A vacuum drying treatment was performed under the drying conditions during the treatment. When only the undercoat layer was peeled off from it, and the temperature was increased at a rate of 10 ° C./min from 30 ° C. to 130 ° C. using TG / DTA6300 (manufactured by SII Nanotechnology Co., Ltd.) The mass change amount of was measured.

-Resistance value-
The resistance value of the undercoat layer was measured as follows. First, the impedance of the undercoat layer was applied from the high frequency side in the frequency range from 1 MHz to 1 mHz, with an AC voltage of 1 Vp-p, using a support such as an aluminum pipe in the impedance measurement sample as a cathode and a gold electrode as an anode, The AC impedance of each sample was measured. The resistance value of the undercoat layer was obtained by fitting the Cole-Cole plot graph obtained from this measurement to an RC parallel equivalent circuit.

-Evaluation of ghost-
By incorporating the photoconductors obtained in Examples and Comparative Examples into a modified DocuCentre 505a (manufactured by Fuji Xerox Co., Ltd.), under the conditions of 10 ° C. and 15% humidity in the condition that there is no static eliminator (no erase). The degree of occurrence of negative ghost due to image history by forming a full-tone image of a halftone image (image density 30%) after forming an image with 100% image density and 2 cm × 2 cm for one cycle of the photoreceptor Was evaluated by visual observation using a limit sample.
・ Evaluation criteria A: Not generated B: Small concentration change generated C: Concentration change generated (a level that causes no problem in practical use)
D: Significant density change occurs (however, -grade is compared to halftone image density)

−Cycle characteristics−
Cycling characteristics are as follows: DocuPrint 505 (Fuji Xerox Co., Ltd.) modified machine incorporating the photoconductors obtained in the examples and comparative examples, and continuous random charts with an image density of 5% under an atmosphere of 28 ° C. and 85 RH%. Immediately after printing, a surface potential probe is installed between the charging device and the exposure device, and the residual potential (V) measured using the surface potential meter Trek 334 (manufactured by Trek) and the residual before 10,000 continuous printing A difference (potential increase in residual potential) from the potential (V) was calculated and evaluated according to the following evaluation criteria.
・ Evaluation criteria A: 10 V or less B: 10 V to 15 V or less C: 15 V to 20 V or less D: 20 V or more

DESCRIPTION OF SYMBOLS 1 Support body, 2 Undercoat layer, 3 Photosensitive layer, 4 Intermediate layer, 5 Protective layer, 7 Electrophotographic photoconductor, 8 Charging device, 9 Power supply, 10 Exposure device, 11 Developing device, 12 Transfer device, 13 Cleaning device, 14 Charger, 15 Fixing device, 31 Charge generation layer, 32 Charge transport layer, 100, 101 Image forming device, P Recording paper (an example of recording medium)

Claims (4)

A support;
An undercoat layer containing at least metal oxide particles and a binder resin, and having a mass change amount of not more than 0.65% by mass from a temperature of 30 ° C. to 130 ° C. in suggested thermogravimetric simultaneous measurement;
A photosensitive layer;
An electrophotographic photoreceptor having the above in this order. 2. The electrophotographic photosensitive member according to claim 1, wherein the undercoat layer has a resistance value of 1 × 10 ⁸ Ω or more and 1 × 10 ¹⁰ Ω or less in AC impedance measurement. An electrophotographic photoreceptor according to claim 1;
A charging device for charging the surface of the electrophotographic photosensitive member;
An electrostatic latent image forming apparatus for forming an electrostatic latent image on the surface of the charged electrophotographic photosensitive member;
A developing device for developing the electrostatic latent image formed on the surface of the electrophotographic photosensitive member with toner to form a toner image;
A transfer device for transferring a toner image formed on the surface of the electrophotographic photosensitive member to a recording medium;
An image forming apparatus comprising: The electrophotographic photoreceptor according to claim 1,
A process cartridge attached to and detached from the image forming apparatus.