JP2018097278A - Image forming apparatus and process cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus of a contact DC charging system, the image forming apparatus capable of printing high-quality images with no color streaks for a long period until photoreceptors reach their end of life.SOLUTION: An image forming apparatus comprises photoreceptors that each include a photosensitive layer and a protective layer on a conductive substrate in order from the conductive substrate. The photosensitive layer or the protective layer contains a triphenylamine compound having a specific structure, and contains at least one of triphenylamine compounds respectively having specific structures different from the specific structure above at a prescribed ratio; the protective layer contains a composition obtained by curing a polymerizable compound and metal oxide particles and is formed to have a thickness within a range of 1.5 to 2.8 μm.SELECTED DRAWING: None

Description

  The present invention relates to an image forming apparatus and a process cartridge used in the image forming apparatus. More specifically, the present invention relates to an image forming apparatus and a process cartridge that can keep the quality of a printed image high over a long period of time.

2. Description of the Related Art In recent years, electrophotographic photosensitive members (hereinafter referred to as “photosensitive members”) constituting image forming apparatuses are widely used that contain an organic photoconductive substance. Photoreceptors containing organic photoconductive substances can be selected from materials that are easy to develop materials that are compatible with various exposure light sources from visible light to infrared light, compared to inorganic photoconductors. It has advantages such as low manufacturing costs.
Some image forming apparatuses employ a contact direct current charging system as a system for charging a photosensitive member. The contact DC charging method is a method in which charging is performed by bringing a conductive charging roller into pressure contact with a photoreceptor and applying a DC voltage to the charging roller. The direct current charging method has the advantages that the current amount is smaller than that of the alternating current charging method, so that the running cost can be suppressed and the photosensitive member is hardly deteriorated.

  On the other hand, in the contact DC charging method, it is difficult to uniformly charge the photoconductor as compared with the contact AC charging method, which causes streaky density unevenness along the axial direction of the photoconductor on the printed image ( There was a problem that color streaks) occurred. However, regarding this point, various attempts have been made such as defining the layer thickness of the photosensitive layer constituting the surface layer portion of the photoreceptor, improving the control of the exposure means for exposing the photoreceptor (see Patent Documents 1 and 2). It was becoming able to be suppressed.

In recent years, due to improvements in the protective layer constituting the surface layer portion of the photoconductor, the wear resistance of the photoconductor has been improved, and it has become possible to withstand longer use. However, it has been found that the variation in the thickness of the photosensitive layer inside the protective layer increases as the photoconductor is used for a long period of time. When the variation in the thickness of the photosensitive layer becomes large, color streaks are generated on the image even if printing itself is possible.
That is, the conventional image forming apparatus has a problem that the image quality is deteriorated before the photosensitive member reaches the end of its life (the protective layer is completely worn out).

Japanese Patent Laid-Open No. 2001-22156 JP, 2006-57637, A

  SUMMARY OF THE INVENTION The present invention has been made in view of the above problems and situations, and a solution to the problem is an image of a contact DC charging system in which a charging roller to which a DC voltage is applied is brought into contact with the photosensitive member to charge the photosensitive member. An object of the present invention is to provide an image forming apparatus capable of printing a high-quality image free of color streaks over a long period of time until the photosensitive member reaches the end of its life.

  In order to solve the above-mentioned problems, the present inventor makes the type of the substance to be contained in the protective layer a specific compound and adjusts the content ratio and the thickness of the protective layer in the process of examining the cause of the above-mentioned problem. As a result, the inventors have found that the above problems can be solved, and have reached the present invention.

That is, the present invention is solved by the following means.
1. An image forming apparatus comprising at least an electrophotographic photosensitive member, a charging roller, a voltage applying unit, an electrostatic latent image forming unit, a toner image forming unit, and a transfer unit,
The voltage applying means is configured to apply a DC voltage to the charging roller;
The electrophotographic photoreceptor comprises at least a photosensitive layer and a protective layer in order from the conductive support side on the conductive support,
The photosensitive layer or the protective layer contains a compound having a structure represented by the following general formula (1) as a charge transport material,
It contains at least one of the compound having the structure represented by the following general formula (2) and the compound having the structure represented by the following general formula (3), and the ratio of the total amount is represented by the following general formula (1) ), A compound having a structure represented by the following general formula (2), and a total metric of a compound having a structure represented by the following general formula (3). It is contained so that it is in the range of 05-0.15 mass%,
The protective layer contains a composition obtained by curing a polymerizable compound and metal oxide particles, and is formed to have a layer thickness in a range of 1.5 to 2.8 μm. Image forming apparatus.

(However, R ₁ , R ₂ and R ₃ in the general formula (1), the general formula (2) and the general formula (3) each independently represent a hydrogen atom, an alkyl group or an alkoxy group. l and n each independently represents an integer of 1 to 5, and m represents an integer of 1 to 4. Note that l, m, and n are integers of 2 or more. In this case, R ₁ , R ₂ and R ₃ may be the same or different.)

  2. 2. The image forming apparatus according to claim 1, wherein the charge transport material is contained in the protective layer.

3. The first item or the item 1, wherein a volume resistance of the charging roller when a voltage of 500 V is applied from the voltage applying unit is in a range of 1.0 × 10 ^{4 to} 1.0 × 10 ⁶ Ω. The image forming apparatus according to Item 2.

  4). Discharge light with a wavelength of 660 nm is applied to the surface of the electrophotographic photosensitive member on the surface of the electrophotographic photosensitive member in the moving direction side of the electrophotographic photosensitive member with respect to the transfer unit and in front of the charging roller in the moving direction of the electrophotographic photosensitive member. The image forming apparatus according to any one of Items 1 to 3, further comprising a pre-exposure device that irradiates the light amount on the surface of the electrophotographic photosensitive member to 100 μW or less.

  5. A process cartridge for use in the image forming apparatus according to any one of items 1 to 4, comprising the electrophotographic photosensitive member and configured to be detachable from the image forming apparatus. Feature process cartridge.

By the above means of the present invention, it is possible to provide an image forming apparatus capable of printing a high-quality image free of color streaks over a long period until the photosensitive member reaches the end of its life.
The expression mechanism or action mechanism of the effect of the present invention is not clear, but is considered as follows.
That is, in the present invention, the protective layer becomes tough by containing the cured composition and metal oxide particles in the protective layer, and as a result, the variation in the layer thickness of the photoreceptor when printing is repeated is reduced. It is thought that the generation of color streaks has been suppressed over a long period of time.

  In addition, since the thickness of the protective layer is set to 1.5 μm or more, it takes a longer time until the protective layer is completely worn. As a result, the photosensitive layer (photosensitivity) is not lost for a long time. It is thought that it has continued to function.

  In addition, since the charge transport material (compound having the structure represented by the general formula (1)) is included in the protective layer, an increase in residual potential and generation of a transfer memory are prevented. The by-product (at least one of the compound having the structure represented by the general formula (2) and the compound having the structure represented by the general formula (3)), the ratio of the total amount is charge transport By containing it so that it is in the range of 0.05 to 0.15 mass% with respect to the total measurement of the substance and the by-product, charge transport after charging of the surplus carrier is suppressed, As a result, it is considered that the generation of color stripes is suppressed.

  In addition, it is considered that the amount of charge trapping is suppressed by setting the thickness of the protective layer to 2.8 μm or less, which also suppresses the generation of color stripes.

Sectional drawing of the image forming apparatus which concerns on one Embodiment of this invention Sectional drawing of the surface layer part of the electrophotographic photoreceptor with which the image forming apparatus of FIG. 1 is equipped

  The image forming apparatus of the present invention is an image forming apparatus comprising at least an electrophotographic photosensitive member, a charging roller, a voltage applying unit, an electrostatic latent image forming unit, a toner image forming unit, and a transfer unit, and the voltage applying unit Is configured to apply a DC voltage to the charging roller, and the electrophotographic photosensitive member includes, on the conductive support, at least a photosensitive layer and a protective layer in order from the conductive support side, The photosensitive layer or the protective layer contains a compound having a structure represented by the above general formula (1) as a charge transport material, a compound having a structure represented by the above general formula (2), and the above general formula ( 3) containing at least one of the compounds having the structure represented by 3), the ratio of the total amount being represented by the compound having the structure represented by the general formula (1) and the general formula (2) Be done In the range of 0.05 to 0.15% by mass with respect to the total weight of the compound having a structure and the compound having the structure represented by the general formula (3), and the protection The layer includes a composition obtained by curing the polymerizable compound and metal oxide particles, and is formed so that the layer thickness is in the range of 1.5 to 2.8 μm. This feature is a technical feature common to the claimed invention.

  As an embodiment of the present invention, the charge transport material is preferably contained in the protective layer. Accordingly, it is considered that charge carriers can be prevented from being trapped in the protective layer, and an increase in residual potential and generation of a transfer memory can be prevented.

Furthermore, in the present invention, the volume resistance of the charging roller when a voltage of 500 V is applied from the voltage applying means is in the range of 1.0 × 10 ^{4 to} 1.0 × 10 ⁶ Ω. preferable. As a result, the volume resistance becomes lower than that of a general-purpose product, so that a stable direct current flow can be realized, and the occurrence of minute charge defects that cause color streak image defects can be suppressed. It is considered that the effect that the image quality can be obtained is obtained.

  Further, in the present invention, on the surface of the electrophotographic photosensitive member on the moving direction side of the electrophotographic photosensitive member relative to the transfer unit and on the front side of the moving direction of the electrophotographic photosensitive member relative to the charging roller. It is preferable to provide a pre-exposure device that irradiates the static elimination light having a wavelength of 660 nm so that the light amount on the surface of the electrophotographic photosensitive member is 100 μW or less. As a result, since there is an upper limit to the amount of static elimination in the static elimination process, it is considered that the effect that it is possible to reduce the occurrence of excess carriers that cause color streak image defects and to obtain good image quality can be obtained. It is done.

  Further, the process cartridge of the present invention can be suitably used for an image forming apparatus.

  Hereinafter, the present invention, its components, and modes and modes for carrying out the present invention will be described in detail. In the following description, “˜” is used to mean that the numerical values described before and after are used as the lower limit value and the upper limit value.

[Image forming apparatus]
The image forming apparatus of the present invention is an image forming apparatus comprising at least an electrophotographic photosensitive member, a charging roller, a voltage applying unit, an electrostatic latent image forming unit, a toner image forming unit, and a transfer unit, and the voltage applying unit Is configured to apply a DC voltage to the charging roller, and the electrophotographic photoreceptor comprises at least a photosensitive layer and a protective layer in this order on a conductive support, and the photosensitive layer or the protective layer. Is characterized by containing a specific compound in a predetermined ratio as described above.

FIG. 1 is a longitudinal sectional view of an image forming apparatus according to an embodiment of the present invention.
The image forming apparatus 100 of the present embodiment is called a tandem color image forming apparatus. As shown in FIG. 1, the apparatus main body 100A and a document image reading apparatus 100B disposed on the apparatus main body 100A are provided. It is equipped with. The apparatus main body 100A includes four sets of image forming units 10Y, 10M, 10C, and 10Bk, an endless belt-shaped intermediate transfer body unit 7, a paper feeding / conveying means 21, and a fixing means 24.

The image forming unit 10Y that forms a yellow image includes a charging unit 2Y disposed around a drum-shaped electrophotographic photosensitive member 1Y (hereinafter referred to as a photosensitive member 1Y) as a first image carrier, and electrostatic latent image formation. It has means 3Y, toner image forming means 4Y, primary transfer roller 5Y as primary transfer means, cleaning means 6Y and pre-exposure device 9Y.
An image forming unit 10M that forms a magenta image includes a drum-shaped electrophotographic photosensitive member 1M (hereinafter referred to as a photosensitive member 1M) as a first image carrier, a charging unit 2M, an electrostatic latent image forming unit 3M, and a toner image. It has a forming unit 4M, a primary transfer roller 5M as a primary transfer unit, a cleaning unit 6M, and a pre-exposure device 9M.
An image forming unit 10C for forming a cyan image includes a drum-shaped electrophotographic photosensitive member 1C (hereinafter referred to as a photosensitive member 1C) as a first image carrier, a charging unit 2C, an electrostatic latent image forming unit 3C, and a toner image. It has a forming unit 4C, a primary transfer roller 5C as a primary transfer unit, a cleaning unit 6C, and a pre-exposure device 9C.
The image forming unit 10Bk that forms a black image includes a drum-shaped electrophotographic photosensitive member 1Bk (hereinafter referred to as a photosensitive member 1Bk) as a first image carrier, a charging unit 2Bk, an electrostatic latent image forming unit 3Bk, and a toner image forming unit. 4Bk, a primary transfer roller 5Bk as a primary transfer unit, a cleaning unit 6Bk, and a pre-exposure device 9Bk.

  The four sets of image forming units 10Y, 10M, 10C, and 10Bk are centered around the photoreceptors 1Y, 1M, 1C, or 1Bk, and charging means 2Y, 2M, 2C, or 2Bk, and electrostatic latent image forming means 3Y, 3M. 3C or 3Bk, rotating toner image forming means 4Y, 4M, 4C or 4Bk, and cleaning means 6Y, 6M, 6C or 6Bk for cleaning the photoreceptors 1Y, 1M, 1C or 1Bk.

  The image forming units 10Y, 10M, 10C, and 10Bk have the same configuration, except that toner images formed on the photoreceptors 1Y, 1M, 1C, and 1Bk are different in color. Therefore, the image forming unit 10Y will be described in detail below as an example.

  The image forming unit 10Y includes a charging unit 2Y, an electrostatic latent image forming unit 3Y, a toner image forming unit 4Y, a cleaning unit 6Y, and a pre-exposure device 9Y around a photoconductor 1Y that is an image forming body. A yellow (Y) toner image is formed on 1Y. In the present embodiment, at least the photoreceptor 1Y, the charging unit 2Y, the toner image forming unit 4Y, and the cleaning unit 6Y are provided in the image forming unit 10Y so as to be integrated.

The charging unit 2Y is a unit that applies a uniform potential to the photoreceptor 1Y. The charging unit 2Y used in the present invention includes a charging roller 2a that contacts the peripheral surface of the photoreceptor 1Y and can rotate with the photoreceptor 1Y, and a voltage applying unit 2b that applies a DC voltage to the charging roller 2a. Yes.
As the charging roller 2a, it is preferable to use a roller having a volume resistance in the range of 1.0 × 10 ^{4 to} 1.0 × 10 ⁶ Ω when a voltage of 500 V is applied from the voltage applying unit 2b. .

  The electrostatic latent image forming unit 3Y performs exposure based on the image signal (yellow) on the photoreceptor 1Y to which the uniform potential is applied by the charging unit 2Y, and generates an electrostatic latent image corresponding to the yellow image. The electrostatic latent image forming means 3Y is a means for forming an LED comprising a light emitting element arranged in an array in the axial direction of the photoreceptor 1Y and an imaging element, or a laser optical system. Etc. are used.

  The pre-exposure device (static discharge lamp) 9Y irradiates the surface of the photosensitive member 1Y with static eliminating light, and is on the moving direction side of the photosensitive member 1Y surface with respect to the endless belt-shaped intermediate transfer member unit 7 charging means 2Y. It is arranged on the front side in the moving direction of the photoreceptor 1Y with respect to the roller 2a. The pre-exposure device 9Y is configured to be able to irradiate the neutralizing light having a wavelength of 660 nm so that the amount of light on the surface of the photoreceptor 1Y is 100 μW or less.

  In the present invention, at least one of the charging unit 2Y, the electrostatic latent image forming unit 3Y, the toner image forming unit 4Y, the primary transfer roller 5Y, and the cleaning unit 6Y, and the photoconductor 1Y are provided in a housing. It is preferable that the process cartridge built in the apparatus is configured so as to be detachable from the apparatus main body 100A. However, individual structures may be individually attached to the apparatus main body 100A.

  The endless belt-shaped intermediate transfer body unit 7 has an endless belt-shaped 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. An image support P as a transfer material (an image support that carries a fixed final image: for example, plain paper, a transparent sheet, etc.) housed in the paper feed cassette 20 is fed by a paper feed transport unit 21, A plurality of intermediate rollers 22A, 22B, 22C, 22D, and a registration roller 23 are conveyed to a secondary transfer roller 5b as a secondary transfer unit, and are secondarily transferred onto the image support P to collectively transfer color images. Is done. The image support P to which the color image has been transferred is fixed by the fixing unit 24, is sandwiched between the discharge rollers 25, and is placed on the discharge tray 26 outside the apparatus. Here, the transfer support for the toner image formed on the photoreceptor 1Y such as an intermediate transfer body or an image support is generically referred to as a transfer medium.

  On the other hand, the endless belt-shaped intermediate transfer body 70 obtained by transferring the color image to the image support P by the secondary transfer roller 5b as the secondary transfer means and then separating the curvature of the image support P has a residual toner by the cleaning means 6b. Removed.

  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 image support P passes through the secondary transfer roller 5b and the secondary transfer is performed.

Further, the housing 8 can be pulled out from the apparatus main body 100A 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-like intermediate transfer body unit 7 is disposed on the left side of the photoreceptors 1Y, 1M, 1C, and 1Bk in the figure. 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, and 74, primary transfer rollers 5Y, 5M, 5C, 5Bk, and cleaning means 6b. It consists of.

  In the image forming apparatus 100 of FIG. 1, a color laser printer is shown, but of course, 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.

[Electrophotographic photoconductor]
Next, the configuration of the photoreceptor 1Y (1M, 1C, 1Bk) provided in the image forming apparatus 100 described above will be described. FIG. 2 is a cross-sectional view of the surface layer when the photoreceptor 1Y (1M, 1C, 1Bk) is cut along a plane orthogonal to the rotation axis thereof.

  In the present invention, the photosensitive member (electrophotographic photosensitive member) is an electrophotographic photosensitive member formed by providing an organic compound with at least one of a charge generating function and a charge transporting function which are indispensable for the constitution of the electrophotographic photosensitive member. All known electrophotographic photoreceptors such as a photoreceptor composed of a known organic charge generating substance or organic charge transporting substance, a photoreceptor composed of a polymer complex with a charge generating function and a charge transporting function. .

The photoreceptor 1Y is of a negative charge type, and as shown in FIG. 2, an intermediate layer 12, a photosensitive layer 13, and a protective layer 14 are formed on the surface of the conductive support 11 in this order from the conductive support 11 side. It has a laminated structure. The photosensitive layer 13 has a laminated structure including a charge generation layer 13a on the intermediate layer 12 side and a charge transport layer 13b on the protective layer 14 side. The intermediate layer 12 is preferably provided in consideration of failure prevention or the like, but may not be provided.
Hereinafter, each layer (conductive support 11, intermediate layer 12, photosensitive layer 13 (charge generation layer 13a, charge transport layer 13b), protective layer 14) constituting the photoreceptor 1Y will be described.

(Conductive support)
The conductive support 11 may be any one as long as it has conductivity, for example, a metal such as aluminum, copper, chromium, nickel, zinc or stainless steel formed into a drum or sheet, aluminum or copper Metal foils such as those laminated on plastic films, aluminum, indium oxide, tin oxide or the like deposited on plastic films, or metals with a conductive layer applied alone or with a binder resin, plastic films or For example, paper.

(Middle layer)
The intermediate layer 12 is a layer having a barrier function for protecting the photosensitive layer 13 and a function for adhering the conductive support 11 and the photosensitive layer 13. The intermediate layer 12 according to this embodiment contains a binder resin and metal oxide particles for adjusting electric resistivity.

  Examples of the binder resin contained in the intermediate layer 12 include casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyamide, polyurethane, and gelatin. Among these, it is preferable to use an alcohol-soluble polyamide resin.

Examples of the metal oxide particles contained in the intermediate layer 12 include metal oxide particles not containing impurities such as alumina, zinc oxide, titanium oxide, tin oxide, antimony oxide, indium oxide, and bismuth oxide, as well as impurities. Examples include, but are not limited to, doped metal oxide particles (indium oxide doped with tin or tin oxide or zirconium oxide doped with antimony). In addition, you may use these metal oxide particles in mixture of 2 or more types. When two or more types are mixed, they may take the form of a solid solution or fusion.
The average particle diameter of the metal oxide particles is preferably 0.3 μm or less, more preferably 0.1 μm or less.
The mixing ratio of the metal oxide particles to the binder resin is preferably in the range of 20 to 400 parts by weight, more preferably in the range of 50 to 200 parts by weight with respect to 100 parts by weight of the binder resin. Is good.

  The layer thickness of the intermediate layer 12 having such a composition is preferably in the range of 0.1 to 15 μm, more preferably in the range of 0.3 to 10 μm.

The intermediate layer 12 is preferably formed by dip coating or the like by preparing a coating solution by dispersing metal oxide particles in a solution obtained by dissolving a binder resin in a solvent using a disperser.
As the solvent for dissolving the binder resin, a solvent in which the metal oxide particles are well dispersed and the polyamide resin is dissolved is preferable. Specifically, alcohols having 2 to 4 carbon atoms such as ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol, t-butanol or sec-butanol are excellent in solubility and coating performance of the polyamide resin.
What is necessary is just to select the density | concentration of binder resin with respect to a solvent suitably according to the layer thickness of the intermediate | middle layer 12, and a production rate.

Examples of means for dispersing the metal oxide particles in the dissolved binder resin include, but are not limited to, an ultrasonic disperser, a ball mill, a sand grinder, and a homomixer.
In preparing the coating solution, in order to improve the storage stability of the binder resin and the dispersibility of the metal oxide particles, for example, a co-solvent such as methanol, benzyl alcohol, toluene, dichloromethane, cyclohexanone, or tetrahydrofuran is used as the solvent. You may use together.
The method for drying the coating solution applied to the surface of the conductive support 11 can be appropriately selected according to the type of solvent and the layer thickness, but thermal drying is preferred.

(Charge generation layer)
The charge generation layer 13a constituting the photosensitive layer 13 is a layer that generates charges by absorbing light. The charge generation layer 13a according to the present embodiment contains a binder resin and a charge generation material.

  As the binder resin, a known resin can be used. For example, polystyrene resin, polyethylene resin, polypropylene resin, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, polyvinyl butyral resin, epoxy resin, polyurethane resin, phenol 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, vinyl chloride-vinyl acetate) -Maleic anhydride copolymer resin) or poly-vinyl carbazole resin, but are not limited thereto.

The charge generating substance is a substance that absorbs light and generates a charge, an azo raw material such as Sudan Red or Diane Blue, a quinone pigment such as pyrenequinone or anthanthrone, a quinocyanine pigment, a perylene pigment, an indigo pigment such as indigo or thioindigo, Examples include, but are not limited to, polycyclic quinone pigments such as pyranthrone and diphthaloylpyrene, and phthalocyanine pigments.
The mixing ratio of the charge generating material to the binder resin is preferably in the range of 1 to 600 parts by weight, more preferably in the range of 50 to 500 parts, based on 100 parts by weight of the binder resin. .

  The layer thickness of the charge generation layer 13a having such a composition varies depending on the characteristics of the binder resin, the characteristics of the charge generation material, the mixing ratio of the charge generation material, etc., but is preferably within a range of 0.01 to 5 μm. Preferably, the thickness is in the range of 0.05 to 3 μm.

The charge generation layer 13a is formed by dispersing a charge generation material in a solution obtained by dissolving a binder resin in a solvent using a disperser to prepare a coating solution, and applying the coating solution to a constant layer thickness using a coating device. It is preferable to prepare the coating film by drying.
Examples of the solvent for dissolving the binder resin include toluene, xylene, dichloromethane, 1,2-dichloroethane, methyl ethyl ketone, cyclohexane, ethyl acetate, butyl acetate, methanol, ethanol, propanol, butanol, methyl cellosolve, ethyl cellosolve, and tetrahydrofuran. , 1-dioxane, 1,3-dioxolane, pyridine, diethylamine and the like, but are not limited thereto.

As a means for dispersing the charge generating substance, an ultrasonic disperser, a ball mill, a sand grinder, a homomixer, or the like can be used, but is not limited thereto.
Moreover, it is preferable from the viewpoint of preventing the occurrence of image defects that the adjusted coating solution is filtered to remove foreign matters and aggregates before coating.
The charge generation layer 13a can also be formed by vacuum deposition of a pigment other than the method described above.

(Charge transport layer)
The charge transport layer 13b constituting the photosensitive layer 13 is a layer that transports the charges generated in the charge generation layer 13a. The charge transport layer 13b used in the present invention contains a binder resin and a charge transport material (CTM).

  As the binder resin for the charge transport layer 13b, a known resin can be used. For example, polycarbonate resin, polyacrylate resin, polyester resin, polystyrene resin, styrene-acrylonitrile copolymer resin, polymethacrylate resin, Styrene-methacrylic acid ester copolymer resins and the like can be mentioned, but preferably polycarbonate, more preferably BPA, BPZ, dimethyl BPA or BPA-dimethyl BPA copolymer is used for crack resistance, abrasion resistance, charging. Good in terms of characteristics.

  In the negatively charged photoreceptor as in the present invention, a hole transporting charge transport material is generally used. As such a charge transport material, known compounds can be used, for example, carbazole derivatives, oxazole derivatives, oxadiazole derivatives, thiazole derivatives, thiadiazole derivatives, triazole derivatives, imidazole derivatives, imidazolone derivatives, imidazolidine derivatives. Bisimidazolidine derivatives, styryl compounds, hydrazone compounds, pyrazoline compounds, oxazolone derivatives, benzimidazole derivatives, quinazoline derivatives, benzofuran derivatives, acridine derivatives, phenazine derivatives, aminostilbene derivatives, triarylamine derivatives, phenylenediamine derivatives, stilbene derivatives, Benzidine derivatives, poly-N-vinylcarbazole, poly-1-vinylpyrene or poly-9-vinylanthracene, The present invention is not limited to these. In addition, these compounds can also be used in mixture of 2 or more types instead of individual.

  In the present invention, the charge transport layer 13b contains, in addition to the charge transport material, a compound having a structure represented by the following general formula (1) as a charge transport material, and the following general formula (2) You may make it contain at least one of the compound which has a structure represented, and the compound which has a structure represented by following General formula (3). Details of specific examples and contents of these compounds will be described later.

The mixing ratio of the charge transport material to the binder resin is preferably in the range of 10 to 500 parts by weight, more preferably in the range of 20 to 100 parts by weight with respect to 100 parts by weight of the binder resin. good.
In addition, you may add antioxidant, an electronic electrically conductive agent, a stabilizer, etc. in the electric charge transport layer 13b. As the antioxidant, those described in JP-A No. 2000-305291 and the electronic conductive agent as described in JP-A Nos. 50-137543 and 58-76483 are preferably used.

  The layer thickness of the charge transport layer 13b having such a composition varies depending on the characteristics of the charge transport material, the characteristics of the binder resin, the mixing ratio, etc., but is preferably in the range of 5 to 40 μm, more preferably in the range of 10 to 30 μm. It is good to be inside.

The charge transport layer 13b is preferably formed by dissolving a binder resin and a charge transport material to prepare a coating solution, applying the coating solution to a constant layer thickness with a coating machine, and drying the coating film.
Examples of the solvent for dissolving the binder resin and the charge transport material include toluene, xylene, dichloromethane, 1,2-dichloroethane, methyl ethyl ketone, cyclohexanone, ethyl acetate, butyl acetate, methanol, ethanol, propanol, butanol, tetrahydrofuran, Examples include, but are not limited to, 1,4-dioxane, 1,3-dioxolane, pyridine, and diethylamine.

(Protective layer)
The protective layer 14 is a layer for protecting the photosensitive layer 13. The protective layer 14 according to the present invention contains a compound having a structure represented by the following general formula (1) as a charge transport material, a compound having a structure represented by the following general formula (2), and the following general formula The compound having at least one of the compounds having the structure represented by (3) and having a total amount of the compound represented by the following general formula (1) and the following general formula (2) Contained in a range of 0.05 to 0.15% by mass with respect to the total weight of the compound having the structure represented by the following formula (3) and the compound having the structure represented by the following general formula (3) The protective layer contains a composition obtained by curing a polymerizable compound and metal oxide particles, and is formed to have a layer thickness in the range of 1.5 to 2.8 μm. To do.

[Compounds having structures represented by general formulas (1), (2) and (3)]

(However, R ₁ , R ₂ and R ₃ in the general formula (1), the general formula (2) and the general formula (3) each independently represent a hydrogen atom, an alkyl group or an alkoxy group. l and n each independently represents an integer of 1 to 5, and m represents an integer of 1 to 4. Note that l, m, and n are integers of 2 or more. In this case, R ₁ , R ₂ and R ₃ may be the same or different.)

Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, a pentyl group, an isopentyl group, and a neopentyl group.
Moreover, as said alkoxy group, a methoxy group or an ethoxy group etc. are mentioned.
In particular, at least one of R ₁ , R ₂ and R ₃ preferably has a propyl group, a butyl group or a pentyl group.

  The compound having the structure represented by the general formula (1) is a charge transport material (CTM) that transports charge carriers in the protective layer 14. Further, this compound has a molecular weight of 450 or less (preferably 320 or more and 420 or less), and can enter the voids of the crosslinked cured resin layer of the protective layer 14. For this reason, it is possible to smoothly inject charge carriers from the charge transport layer 13b without deteriorating the wear resistance of the protective layer 14, and the protective layer does not cause an increase in residual potential and generation of a transfer memory. Charges can be transported to the 14 surfaces.

Specific examples of the compound having the structure represented by the general formula (1) are shown below.
These compounds can be synthesized by a known synthesis method, for example, the method described in paragraphs 0044 to 0049 of JP-A-2006-143720.

The ratio of the compound having the structure represented by the general formula (1) in the protective layer 14 is preferably within the range of 10 to 50 parts by mass, more preferably when the resin component of the protective layer 14 is 100 parts by mass. It is good to set it in the range of 10-35 mass parts.
This ratio can be verified by decomposing the protective layer 14 and measuring the mass of the resin component in the protective layer 14 and the mass of the compound having the structure represented by the general formula (1).

The compounds having the structures represented by the general formula (2) and the general formula (3) have almost the same effect on the electrophotographic characteristics, and both have the structure represented by the general formula (1). Similar to the compound having the above, it functions as a charge transport material (CTM).
Moreover, the compound which has a structure represented by the said General formula (1), the compound which has a structure represented by the said General formula (2), and the compound which has a structure represented by the said General formula (3) The ratio of the total amount of the compound having the structure represented by the general formula (2) and the compound having the structure represented by the general formula (3) to the total weight is in the range of 0.05 to 0.15% by mass. It is inside.
The compounds having the structures represented by the general formulas (2) and (3) are synthesized as by-products in the process of synthesizing the compound having the structure represented by the general formula (1). . Hereinafter, a method for synthesizing the compound having the structure represented by the general formula (1) that can obtain the compound having the structure represented by the general formulas (2) and (3) will be described.

The compound having the structure represented by the general formula (1) is usually synthesized by a coupling reaction between a diarylamine and an aryl halide. At this time, a small amount of the compound having the structure represented by the general formula (2) or the general formula (3) is also produced.
Which of the compound having the structure represented by the general formula (2) and the compound having the structure represented by the general formula (3) is generated depends on the synthesis method. That is, if the method of the following (Synthesis method A) is used, the compound which has a structure represented by the said General formula (2) will produce | generate, and if the method of the following (Synthesis method B) is used, the said General formula (3) A compound having a structure represented by

(Synthesis Method A)

(However, X in the above formula represents a chlorine atom, a bromine atom or an iodine atom. In addition, R ₁ , R ₂ and R ₃ in the above formula are each independently represented by the general formula (1) or the general formula ( In the above formula, l and n each independently represent an integer of 1 to 5, and m represents an integer of 1 to 4. When l, m and n are integers of 2 or more, R ₁ , R ₂ and R ₃ may be the same or different.)

(Synthesis method B)

(However, X in the above formula represents a chlorine atom, a bromine atom or an iodine atom. In addition, R ₁ , R ₂ and R ₃ in the above formula are each independently represented by the general formula (1) or the general formula ( 3) represents a group having the same meaning as 1), and l and n in the above formula each independently represent an integer of 1 to 5, and m represents an integer of 1 to 4. When l, m and n are integers of 2 or more, R ₁ , R ₂ and R ₃ may be the same or different.)

  A compound having the structure represented by the general formula (1) and a compound having the structure represented by the general formula (2) or the general formula (3) synthesized using the synthesis method A or the synthesis method B. By purifying the mixture, the compound having the structure represented by the general formula (2) or the general formula (3), which is an impurity, has a structure in which the content ratio is represented by the general formula (1). 0.05 to 0.15% by mass with respect to the total weight of the compound having the compound represented by the general formula (2) or the compound having the structure represented by the general formula (3) Try to be within range. As a purification method, distillation or column chromatography can be used.

  When both the compound having the structure represented by the general formula (2) and the compound having the structure represented by the general formula (3) are contained, the respective synthesis methods A and B are used. The ratio of the total amount of the compound having the structure represented by the general formula (2) and the compound having the structure represented by the general formula (3) is the ratio of the total amount obtained by the above general formula (1). 0.05 relative to the total weight of the compound having the structure represented by formula (2), the compound having the structure represented by formula (2), and the compound having the structure represented by formula (3). It can obtain by adjusting and mixing so that it may become in the range of -0.15 mass%.

In the present invention, the charge transport layer 13b may contain a compound having a structure represented by the general formula (1), the general formula (2), and the general formula (3). Is as described above. Even when these compounds are contained in the charge transport layer 13b, the ratio of the total amount of the compounds having the structures represented by the general formulas (2) and (3) is the above general formulas (1), (2) and It shall be in the range of 0.05-0.15 mass% with respect to the comprehensive measurement of the compound represented by (3).
In addition, when these compounds are contained in the charge transport material 13b, it is not necessary to contain them in the protective layer 14.

(Polymerizable compound)
As the polymerizable compound to be contained in the protective layer 14, a monomer that is generally polymerized (cured) by irradiation with actinic rays such as ultraviolet rays or an electron beam or heat and becomes a binder resin of a photoreceptor such as polystyrene or polyacrylate is preferably used. Is preferred. More preferably, a styrene monomer, an acrylic monomer, a methacrylic monomer, a vinyl toluene monomer, a vinyl acetate monomer, and an N-vinyl pyrrolidone monomer are used. A radically polymerizable compound having an acryloyl group (CH ₂ ═CHCO—) or a methacryloyl group (CH ₂ ═CCH ₃ CO—) is particularly preferred because a curing reaction is possible.

Below, the example of a radically polymerizable compound is shown.
In addition, these radically polymerizable compounds may be used alone or in combination. In addition, these polymerizable compounds may use monomers or may be used after oligomerization.

(However, R in the above formulas M1 to M16 represents the following acryloyl group, and R ′ represents the following methacryloyl group.)

  The radical polymerizable compound is preferably a compound having 3 or more functional groups (reactive groups). Further, the radical polymerizable compound may be used in combination of two or more kinds of compounds, but even in this case, it is preferable to use 50% by mass or more of the radical polymerizable compound having 3 or more functional groups. Further, the curable functional group equivalent, ie, “molecular weight / number of functional groups of polymerizable compound” is preferably 1000 or less, and more preferably 500 or less. This increases the crosslink density and improves wear resistance.

(Polymerization initiator)
When the radical polymerizable compound used in the present invention is reacted, a method of reacting by electron beam cleavage, a method of reacting with light or heat by adding a radical polymerization initiator, and the like are used.
As the polymerization initiator, either a photopolymerization initiator or a thermal polymerization initiator can be used. In addition, both light and heat initiators can be used in combination.

  Examples of the photopolymerization initiator include diethoxyacetophenone, 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, 4- (2-hydroxyethoxy) phenyl- (2-hydroxy-2-propyl) ketone, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butanone-1 (“Irgacure 369” manufactured by BASF Japan Ltd.), 2-hydroxy- 2-methyl-1-phenylpropan-1-one, 2-methyl-2-morpholino (4-methylthiophenyl) propan-1-one, 1-phenyl-1,2-propanedione-2- (o-ethoxycarbonyl) ) Acetophenone-based or ketal-based photopolymerization initiators such as oximes; benzoin, benzoin methyl ether Benzoin ether photopolymerization initiators such as benzoin ethyl ether, benzoin isobutyl ether, and benzoin isopropyl ether; benzophenone, 4-hydroxybenzophenone, methyl o-benzoylbenzoate, 2-benzoylnaphthalene, 4-benzoylbiphenyl, 4-benzoyl Benzophenone-based photopolymerization initiators such as phenyl ether, acrylated benzophenone, and 1,4-benzoylbenzene; 2-isopropylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, or 2,4 -Thioxanthone photopolymerization initiators such as dichlorothioxanthone.

  Examples of other photopolymerization initiators include ethyl anthraquinone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylethoxyphosphine oxide, and bis (2,4,6-trimethylbenzoyl). Phenylphosphine oxide (“Irgacure 819” manufactured by BASF Japan Ltd.), bis (2,4-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, methylphenylglyoxyester, 9,10-phenanthrene, Examples include acridine compounds, triazine compounds, and imidazole compounds. In addition, a photopolymerization accelerator having a photopolymerization promoting effect can be used alone or in combination with the photopolymerization initiator. Examples of the photopolymerization accelerator include triethanolamine, methyldiethanolamine, ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, (2-dimethylamino) ethyl benzoate, and 4,4′-dimethylamino. Examples include benzophenone.

  On the other hand, examples of the thermal polymerization initiator include ketone peroxide compounds, peroxyketal compounds, hydroperoxide compounds, dialkyl peroxide compounds, diacyl peroxide compounds, peroxydicarbonate compounds, and peroxy compounds. Examples include ester compounds. These thermal polymerization initiators are also disclosed in company product catalogs.

  As the polymerization initiator used in the present invention, a photopolymerization initiator is preferable, an alkylphenone compound and a phosphine oxide compound are preferable, and an initiator having an α-hydroxyacetophenone structure or an acylphosphine oxide structure is more preferable. Agents are preferred.

  These polymerization initiators may be used alone or in combination of two or more. The content of the polymerization initiator is in the range of 0.1 to 20 parts by mass, preferably in the range of 0.5 to 10 parts by mass with respect to 100 parts by mass of the acrylic compound.

[Metal oxide particles]
The metal oxide particles contained in the protective layer 14 are preferably those having a volume resistivity in the range of 1 × 10 ³ to 1 × 10 ¹¹ Ω · cm. In addition, volume resistivity (Volume Resistivity; Ω · cm) is a value indicating the electrical resistance, which is a measure of the conductivity of a substance, per unit volume (1 cm × 1 cm × 1 cm). That is, it is obtained by passing a constant current I (A) through the cross-sectional area W × t and measuring a potential difference V (V) between electrodes separated by a distance L.
Volume resistivity VR (Ω · cm) = (W × t / L) × (V / I)
Cross-sectional area = W × t
Resistance R = V / I
The volume resistivity (Ω · cm) of the metal oxide fine particles in the present invention is a direct current when a container having electrodes arranged in parallel with an interval of 2 mm is filled with metal oxide fine particles and the potential difference between both electrodes is set to 500V. The value obtained by measuring the resistance with “4329A High Resistance Meter” manufactured by Agilent Technologies, Inc. is used.

  Examples of the metal oxide particles having such volume resistivity include silica (silicon oxide), magnesium oxide, zinc oxide, lead oxide, alumina (aluminum oxide), zirconium oxide, and tin oxide when transition metals are included. , Titania (titanium oxide), niobium oxide, molybdenum oxide, or vanadium oxide, among which tin oxide particles, titanium oxide particles, or zinc oxide particles are preferably used.

Further, the number average primary particle size of the metal oxide particles according to the present invention is preferably in the range of 1 to 300 nm, more preferably in the range of 3 to 100 nm.
The number average primary particle size of the metal oxide particles in the present invention was taken with a scanning electron microscope (manufactured by JEOL Ltd.) at a magnification of 10,000 times of the metal oxide particles, and 300 of them were taken. Particles (excluding agglomerated particles) are randomly extracted and captured by a scanner, and the captured photographic image is analyzed using an automatic image processing analyzer “LUZEX AP (Nireco Corp .; software version Ver. 1.32)”. It is the value obtained by analyzing.

The ratio of the metal oxide particles in the protective layer 14 is preferably in the range of 30 to 150 parts by mass, more preferably in the range of 50 to 100 parts by mass, when the resin component of the protective layer 14 is 100 parts by mass. It is good to do.
Each said mass part can be verified from the mass of the protective layer 14, the mass of the metal oxide particles taken out by decomposing the resin layer of the protective layer 14, and the like.

[Surface-modified metal oxide particles]
The metal oxide particles according to the present invention are preferably surface-modified with a surface modifier containing a compound having a radical polymerizable functional group, particularly a surface modifier containing a compound having an acryloyl group or a methacryloyl group. .
The modification amount of the surface modifier to the metal oxide particles is preferably in the range of 0.1 to 200 parts by mass of the surface modifier with respect to 100 parts by mass of the metal oxide particles before modification.

Examples of the compound having an acryloyl group or a methacryloyl group used as the surface modifier include those shown below.
_{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) 3 Si (CH 3) (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

  Further, the protective layer 14 may be further added with various antioxidants, or may be added with various lubricant particles, for example, fluorine atom-containing resin particles. Examples of the fluorine atom-containing resin particles include a tetrafluoroethylene resin, a trifluorinated ethylene chloride resin, a hexafluorochloroethylene propylene resin, a vinyl fluoride resin, a vinylidene fluoride resin, an ethylene difluoride dichloride resin, and One or two or more of these copolymers are preferably selected as appropriate, and in particular, a tetrafluoroethylene resin or a vinylidene fluoride resin is preferable.

  The thickness of the protective layer 14 having such a composition is preferably in the range of 1.5 to 2.8 μm, more preferably in the range of 1.6 to 2.5 μm.

(Method for forming protective layer)
The protective layer 14 in the present invention includes a compound having a structure represented by the general formula (1), a compound having a structure represented by the general formula (2), and a structure represented by the general formula (3). A coating solution prepared by mixing at least one of the compounds having metal oxide particles (surface-modified metal oxide particles), a polymerizable compound, a polymerization initiator and the like in a solvent, and applying the coating solution to the charge transport layer 13b; After coating on the surface, it can be formed by drying and polymerization.

Prior to preparation of the coating solution, each material is manufactured.
What is necessary is just to manufacture a metal oxide particle using a well-known manufacturing method.
In addition, when using the manufactured metal oxide particle by surface modification, it is as follows. Here, a case where the metal oxide is titanium oxide and the compound having a radical polymerizable functional group is a silane compound will be described as an example. First, a slurry (suspension of solid particles) containing titanium oxide particles and a surface modifier containing a silane compound is placed in a surface modifier and wet pulverized.

  The titanium oxide particles surface-modified with a surface modifier containing a compound having a radically polymerizable functional group according to the present invention are obtained by replacing the titanium oxide particles with a silane compound having a radically polymerizable functional group (the above exemplified compounds) and the like. It can be obtained by using and surface modification. When the surface coating is modified, with respect to 100 parts by mass of the titanium oxide particles before modification, the silane compound is used as a surface modifier within the range of 0.1 to 200 parts by mass and the solvent within the range of 50 to 5000 parts by mass. It is preferred to modify using a wet media dispersing device.

In the present invention, it is preferable to use a wet media dispersion type device as the surface modification device. The wet media dispersion type device is a device that crushes and disperses the aggregated particles of metal oxide particles by filling beads in the container as media and rotating the stirring disk mounted perpendicular to the rotation axis at high speed. It is. By using this wet media dispersion type apparatus, the refinement of the titanium oxide particles and the surface modification of the titanium oxide particles are simultaneously performed.
In addition, the specific configuration of the apparatus is not particularly limited as long as the metal oxide particles can be refined and surface-modified. For example, various types such as a vertical type / horizontal type, a continuous type, a batch type, etc. 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 apparatuses use a grinding medium such as balls or beads to finely pulverize and disperse by impact crushing, friction, shearing, shear stress, or the like.

Examples of beads that can be used in the wet media dispersion type apparatus include balls made of glass, alumina, zircon, zirconia, steel, flint stone, or the like, and those made of zirconia or zircon are particularly preferable. The size of the beads to be used is usually about 1 to 2 mm in diameter, but in the present invention, it is preferable to use those having a diameter of about 0.1 to 1.0 mm.
Further, the disk and container used in the wet media dispersion type apparatus can be made of various materials such as stainless steel, nylon, ceramic, etc. In the present invention, in particular, zirconia or silicon carbide. It is preferable to use a ceramic disk or container.

After refinement and surface modification of the titanium oxide particles, the solvent is removed to form a powder. In this way, titanium oxide particles surface-modified with a fine silane compound can be obtained.
Here, titanium oxide particles have been described as an example of metal oxide particles, but metal oxide particles such as alumina, zinc oxide, tin oxide, and silica also have hydroxy groups on the surface in the same manner as titanium oxide. Therefore, metal oxide particles surface-modified with a surface modifier can be obtained in the same manner as titanium oxide.

  The method for producing the compound having the structure represented by the general formulas (1), (2) and (3) is as described above.

  After manufacturing each material, a coating solution is prepared. Here, each material is mixed in the solvent while adjusting the amount so that the ratio in the protective layer is within a desired range. As the solvent used here, methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol, t-butanol, sec-butanol, benzyl alcohol, toluene, xylene, dichloromethane, methyl ethyl ketone, cyclohexane, ethyl acetate, butyl acetate, Examples include, but are not limited to, methyl cellosolve, ethyl cellosolve, tetrahydrofuran, 1-dioxane, 1,3-dioxolane, pyridine or diethylamine.

  After preparing the coating solution, the coating solution is applied to the surface of the incomplete photoreceptor formed up to the photosensitive layer 13. As in the case of forming the photosensitive layer 13, the coating solution is applied by a dip coating method, a spray coating method, a spinner coating method, a bead coating method, a blade coating method, a beam coating method or a slide hopper method (quantity-regulated coating). Known methods) can be used.

After applying the coating solution, the coating solution is dried. The timing of drying may be any time before irradiation with active rays, during irradiation with active rays, or after irradiation with active rays, but in the present invention, drying is preferably performed after application and before irradiation with active rays. .
The drying method for the coating solution may be either natural drying or heat drying.
Further, the drying conditions of the coating solution can be appropriately selected depending on the type of solvent, the thickness of the coating solution, and the like. The drying temperature is preferably in the range of room temperature to 180 ° C, more preferably in the range of 80 to 140 ° C. The drying time is preferably in the range of 1 to 200 minutes, more preferably in the range of 5 to 100 minutes.

  In addition, the coating liquid is irradiated with actinic rays at any timing before drying, during drying or after drying (as described above, preferably after drying). As the active ray, ultraviolet rays and electron beams are particularly preferable.

The ultraviolet light source is not particularly limited as long as it is a light source that generates ultraviolet light. 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, or a flash (pulse) Xenon or the like can be used. The irradiation conditions vary for each light source, the irradiation amount of actinic rays is normally 5~500mJ / cm ^2, preferably between 5 to 100 mJ / cm ^2. The power of the lamp is preferably in the range of 0.1 to 5 kW, more preferably in the range of 0.5 to 3 kW.

  The electron beam source is not particularly limited, but generally, a curtain beam type electron beam accelerator capable of obtaining a large output at a relatively low cost is effectively used for such electron beam irradiation. The acceleration voltage during electron beam irradiation is preferably in the range of 100 to 300 kV. The absorbed dose is preferably in the range of 0.5 to 10 Mrad.

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

  When irradiated with actinic radiation, the reaction between the radical polymerizable functional groups of the surface-modified metal oxide particles, the reaction between the radical polymerizable functional group and the polymerizable compound, the reaction between the polymerizable compounds, etc., proceed respectively. Then, the coating solution is cured and the protective layer 14 is formed.

The present invention will be described in detail while showing an actual configuration and its effects. However, of course, the embodiments of the present invention are not limited to these.
In this example, the compound having the structure represented by the general formula (1) is referred to as the charge transport material (1), and the compound having the structure represented by the general formula (2) is referred to as the charge transport material (2). ), And the compound having the structure represented by the general formula (3) will be referred to as a charge transport material (3).

[Preparation of surface-modified metal oxide particles]
As the metal oxide particles, tin oxide having a number average primary particle size of 20 nm and a volume resistivity of 1.05 × 10 ⁵ Ω · cm (manufactured by CIK Nanotech Co., Ltd.) is used, and an exemplary compound as a compound having a radical polymerizable functional group Using (S-15), as shown below, surface modification with a compound having a radical polymerizable functional group was prepared.

  Specifically, a mixed solution of 100 parts by mass of tin oxide, 30 parts by mass of the exemplified compound (S-15) as a surface modifier, and 300 parts by mass of a mixed solvent of toluene / isopropyl alcohol = 1/1 (mass ratio) is obtained. The beads were placed in a sand mill together with the beads and stirred at a rotational speed of 1500 rpm in an environment of about 40 ° C. to effect surface modification with a compound having a radical polymerizable functional group. Further, the mixture was taken out, put into a Henschel mixer, stirred for 15 minutes at a rotation speed of 1500 rpm, and then dried at 120 ° C. for 3 hours, thereby completing the surface modification of tin oxide with the compound having a radical polymerizable functional group. Then, surface-modified tin oxide (hereinafter referred to as “surface-modified metal oxide particles 1”) was obtained. The surface of the tin oxide particles was coated with the S-15 compound by the surface modification with the compound having the radical polymerizable functional group.

(Synthesis of charge transport materials)
(Synthesis Example 1)
Under a nitrogen stream, put 0.52 g (2.7 mmol) of cuprous iodide, 1.08 g (5.5 mmol) of 1,10-phenanthroline monohydrate, and 10 mL of xylene in a four-headed flask equipped with a condenser. And stirred at 60 ° C. for 30 minutes. Next, 5.00 g (27.3 mmol) of 4-methyldiphenylamine, 9.01 g (32.8 mmol) of 4-iodo-4′-n-propylbiphenyl, 3.28 g (34.1 mmol) of sodium tert-butoxide, xylene 20 mL was added and it recirculate | refluxed at 130 degreeC for 6 hours. After allowing to cool, 100 mL of water was added and stirred for 30 minutes, and the organic layer was washed with water until the aqueous layer became neutral. After drying the organic layer with sodium sulfate, toluene was distilled off.

The obtained crude product was purified using a silica gel column (developing solvent: n-heptane / toluene = 1/1), and 7.52 g (yield 73%) of charge transport material (1) (Exemplary Compound CTM- 13) was obtained. And the purity of the main component was calculated. The purity was calculated from the area value of high performance liquid chromatography.
Further, high performance liquid chromatography was measured under the following conditions.
Column: Shim-pack CLC-Phenyl (manufactured by Shimadzu Corporation)
Developing solvent: methanol / THF / water = 5/3/2
Flow rate: 1 mL / min
Detection wavelength: 290 nm

The retention time of the main component was 9.5 minutes, and the purity was 98.83% (area value). Further, when the impurity component having a retention time of 18.5 minutes was further separated by a silica gel column (developing solvent: n-heptane / toluene = 4/1) and subjected to structural analysis, the impurity component was found to have the following structure from mass spectrum and NMR. It was a p-phenylenediamine compound of the formula (F-1: charge transport material (2)). Content of (F-1) calculated | required from the analytical curve method by a high performance liquid chromatography was 0.15 mass% with respect to CTM-13.
Hereinafter, the exemplified compound (CTM-13) containing the p-phenylenediamine compound (F-1) is referred to as “CT-1”.

(Synthesis Example 2)
Under a nitrogen stream, 0.37 g (1.6 mmol) of palladium acetate and 1.33 g (6.6 mmol) of tri-tert-butylphosphine were placed in a four-headed flask equipped with a condenser and stirred at room temperature for 30 minutes. Next, 9.41 g (32.8 mmol) of N-phenyl-4′-propylbiphenylamine, 3.45 g (22 mmol) of 4-bromotoluene and 20 mL of toluene, 6.29 g (65.5 mmol) of sodium-tert-butoxide were added. The mixture was refluxed for 2 hours. After allowing to cool, 100 mL of water was added and stirred for 10 minutes, and the organic layer was washed with water until the aqueous layer became neutral. After drying the organic layer with sodium sulfate, toluene was distilled off.

The obtained crude product was purified using a silica gel column (developing solvent: n-heptane / toluene = 1/1), and 6.46 g (yield 81%) of the charge transport material (1) (Exemplary Compound CTM- 13) was obtained.
The purity of the exemplified compound (CTM-13) was 99.52% (area value). Further, structural analysis of the impurity component revealed that it was a p-phenylenediamine compound (F-2: charge transport material (3)) having the following structural formula. Content of (F-2) was 0.07 mass% with respect to CMT-13.
Hereinafter, the exemplified compound (CTM-13) containing this p-phenylenediamine compound (F-2) is referred to as “CT-2”.

[Production of photoconductor]
(Production of photoreceptors according to Examples 1 and 3 to 5)
<Conductive support>
First, a plurality of (four) conductive supports 11 (see FIG. 2) were prepared by cutting the surface of a cylindrical aluminum rod having a diameter of 60 mm to make the surface fine and rough.

<Intermediate layer>
The following components were mixed and dispersed by a batch method for 10 hours using a sand mill as a disperser. Then, the dispersion was diluted twice with the same solvent, and allowed to stand overnight, followed by filtration (filter; using a lime mesh 5 μm filter manufactured by Nippon Pole Co., Ltd.) to prepare an intermediate layer coating solution.
Polyamide resin CM8000 (manufactured by Toray Industries, Inc.) 1 part by mass Titanium oxide SMT500SAS (manufactured by Teika Co., Ltd.) 3 parts by mass Methanol 10 parts by mass And, on the surface of each of the plurality of conductive supports 11, this intermediate layer is applied. The liquid was applied by a dip coating method to form an intermediate layer 12 having a dry layer thickness of 2 μm.

<Charge generation layer>
First, the charge generation material CG-1 was synthesized as follows.
(1) Synthesis of amorphous titanyl phthalocyanine 1,3-diiminoisoindoline; 29.2 parts by mass are dispersed in 200 parts by mass of o-dichlorobenzene, and titanium tetra-n-butoxide; 20.4 parts by mass are added. It heated at 150-160 degreeC for 5 hours under nitrogen atmosphere. 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 by mass (yield 91%) of crude titanyl phthalocyanine.

Next, the crude titanyl phthalocyanine was dissolved in 250 parts by mass of concentrated sulfuric acid at 5 ° C. or less for 1 hour with stirring, and this was poured into 5000 parts by mass of water at 20 ° C. The precipitated crystals were filtered and washed thoroughly with water to obtain 225 parts by weight of a wet paste product.
Next, the wet paste product was frozen in a freezer, thawed again, filtered and dried to obtain 24.8 parts by mass of amorphous titanyl phthalocyanine (yield 86%).

(2) Synthesis of (2R, 3R) -2,3-butanediol adduct titanyl phthalocyanine (CG-1) 10.0 parts by mass of the above-mentioned amorphous titanyl phthalocyanine and (2R, 3R) -2,3-butanediol 0.94 parts by mass (0.6 equivalent ratio) (equivalent ratio is equivalent to titanyl phthalocyanine, the same applies hereinafter) is mixed with 200 parts by mass of orthodichlorobenzene (ODB) and stirred at 60 to 70 ° C. for 6.0 hours. did. 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 mass parts was obtained.

In the X-ray diffraction spectrum of 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 It is presumed to be a mixed crystal of titanyl phthalocyanine.

It was 31.2 m < ² > / g when the BET specific surface area of the obtained CG-1 was measured with the flow type specific surface area automatic measuring device (Micrometrics flow soap type: Shimadzu Corporation).

Next, the following components are mixed and dispersed using a circulating ultrasonic homogenizer RUS-600TCVP (manufactured by Nippon Seiki Seisakusho, 19.5 kHz, 600 W) at a circulating flow rate of 40 L / H for 0.5 hours and 10 hours, A charge generation layer coating solution was prepared.
Charge generation substance: 24 parts by mass of the pigment (CG-1) 12 parts by mass of polyvinyl butyral resin “S-REC BL-1” 400 parts by mass of 3-methyl-2-butanone / cyclohexanone = 4/1 (V / V) The charge generation layer coating solution was applied to the surface of each intermediate layer 12 by a dip coating method to form a charge generation layer 13a having a dry layer thickness of 0.3 μm.

<Charge transport layer>
The following components were mixed and dissolved to prepare a charge transport layer coating solution.
Charge transport material (compound A) 225 parts by mass Binder: Polycarbonate Z (Z300: manufactured by Mitsubishi Gas Chemical Co., Inc.) 300 parts by mass Antioxidant (Irganox 1010: manufactured by BASF Japan Ltd.) 6 parts by mass THF (tetrahydrofuran) 1600 Part by mass Toluene 400 parts by mass Silicone oil (KF-50: manufactured by Shin-Etsu Chemical Co., Ltd.) 1 part by mass

Then, this charge transport layer coating solution was applied to the surfaces of a plurality of unfinished photoreceptors previously formed up to the charge generation layer 13a using a slide hopper coating machine (circular amount regulation type coating machine). The applied charge generation layer coating solution was dried to form a charge transport layer 13b having a layer thickness of 20 μm.
Hereinafter, the charge transport layer 13b having such a composition is referred to as “charge transport layer C-1”.

<Protective layer>
Subsequently, the following materials were mixed and stirred, and sufficiently dissolved and dispersed to prepare a protective layer coating solution. The charge transport materials (1), (2) and (3) are obtained by changing the content ratios of F-1 and F-2 in the CT-1 and CT-2 obtained in the above-described charge transport material synthesis step. The following proportions were obtained by adjusting and mixing.
Polymerizable compound (trimethylolpropane trimethacrylate) 100 parts by mass Metal oxide particles (tin oxide) 50 parts by mass Polymerization initiator (“Irgacure 819” manufactured by BASF Japan Ltd.) 7.5 parts by mass Charge transport material (1 ) (CTM-13) 10 parts by mass Charge transport substance (2) (F-1) 0.005 part by mass Charge transport substance (3) (F-2) 0.005 part by mass sec-butyl alcohol 100 parts by mass

  Then, this protective layer coating solution is applied to the surfaces of a plurality of incomplete photoreceptors that have been formed up to the charge transport layer C-1 in advance using a circular slide hopper applicator, respectively, and dried. I let you. Thereafter, the incomplete photoconductor was placed under a nitrogen stream, and a metal halide lamp was installed such that the distance from the light source to the surface of the incomplete photoconductor was 100 mm. Then, the surface of the incomplete photoconductor was irradiated with ultraviolet rays at a lamp output of 4 kW for 1 minute to cure the applied protective layer coating solution to form a protective layer 14 having a layer thickness of 2.0 μm. Thus, a plurality of photoconductors 1Y having the same configuration were produced. Although these photoconductors 1Y have the same configuration, they will be used later in a plurality of image forming apparatuses having different settings (volume resistance of the charging roller and amount of light on the surface of charge removal light). The photoreceptor 1 </ b> Y is distinguished as the photoreceptor 1 </ b> Y according to Examples 1 and 3 to 5.

(Production of Photoreceptor According to Example 2)
A photoconductor 1Y according to Example 2 was produced in the same manner as in Examples 1 and 3 to 5 except that the thickness of the protective layer was 1.6 μm.

(Production of Photoreceptor According to Example 6)
<Charge transport layer>
First, the following materials were mixed and dissolved to prepare another charge transport layer coating solution. The charge transport materials (1), (2) and (3) are obtained by changing the content ratios of F-1 and F-2 in the CT-1 and CT-2 obtained in the above-described charge transport material synthesis step. The following proportions were obtained by adjusting and mixing.
Charge transport material (compound A) 125 parts by mass Charge transport material (1) (CTM-13) 100 parts by mass Charge transport material (2) (F-1) 0.05 part by mass Charge transport material (3) (F- 2) 0.05 part by weight Binder: Polycarbonate Z (Z300: manufactured by Mitsubishi Gas Chemical Co., Ltd.) 300 parts by weight Antioxidant (Irganox 1010: manufactured by BASF Japan) 6 parts by weight THF (tetrahydrofuran) 1600 parts by weight Toluene 400 1 part by mass Silicone oil (KF-50: manufactured by Shin-Etsu Chemical Co., Ltd.)

Then, this charge transport layer coating solution was applied to the surface of the incomplete photoconductor previously formed up to the charge generation layer 13a using a circular slide hopper applicator. The applied charge generation layer coating solution was dried to form a charge transport layer 13b having a layer thickness of 20 μm.
Hereinafter, the charge transport layer 13b having such a composition is referred to as “C-2”.

<Protective layer>
Subsequently, a protective layer coating solution containing no charge transport material is prepared, and applied to the surface of the incomplete photoreceptor previously formed up to the charge transport layer C-2 using a circular slide hopper coating machine and dried. It was. Thereafter, the incomplete photoconductor was placed under a nitrogen stream, and a metal halide lamp was installed such that the distance from the light source to the surface of the incomplete photoconductor was 100 mm. Then, the surface of the incomplete photoconductor was irradiated with ultraviolet rays at a lamp output of 4 kW for 1 minute to cure the applied protective layer coating solution to form a protective layer 14 having a layer thickness of 2.0 μm. Thus, a photoreceptor 1Y according to Example 6 was produced.

(Production of Photoreceptor According to Comparative Example 1)
As a charge transport material, a protective layer coating solution containing only the charge transport material (1) (not containing the charge transport material (2) and the charge transport material (3)) is prepared, and a circular slide hopper coating machine is used. Then, it was applied to the surface of the incomplete photoreceptor previously formed up to the charge transport layer C-1, and dried. Thereafter, the incomplete photoconductor was placed under a nitrogen stream, and a metal halide lamp was installed such that the distance from the light source to the surface of the incomplete photoconductor was 100 mm. Then, the surface of the incomplete photoconductor was irradiated with ultraviolet rays at a lamp output of 4 kW for 1 minute to cure the applied protective layer coating solution to form a protective layer 14 having a layer thickness of 2.0 μm. Thus, a photoreceptor according to Comparative Example 1 was produced.

(Production of Photoreceptor According to Comparative Example 2)
Protection in which the content ratio of the charge transport material (2) and the charge transport material (3) is 0.20% by mass (twice that of the protective layer coating solution used in the production of the photoreceptor 1Y of Examples 1 to 5). A layer coating solution was prepared, applied to the surface of the incomplete photoreceptor previously formed up to the charge transport layer C-1 using a circular slide hopper coating machine, and dried. Thereafter, the incomplete photoconductor was placed under a nitrogen stream, and a metal halide lamp was installed such that the distance from the light source to the surface of the incomplete photoconductor was 100 mm. Then, the surface of the incomplete photoconductor was irradiated with ultraviolet rays at a lamp output of 4 kW for 1 minute to cure the applied protective layer coating solution to form a protective layer 14 having a layer thickness of 2.0 μm. Thus, a photoreceptor according to Comparative Example 2 was produced.

(Production of photoconductor according to Comparative Example 3)
A photoconductor 1Y according to Comparative Example 3 was produced in the same manner as in Examples 1 and 3 to 5 except that the thickness of the protective layer was 3.0 μm.

(Production of Photoreceptor According to Comparative Example 4)
A photoconductor 1Y according to Comparative Example 4 was produced in the same manner as in Examples 1 and 3 to 5 except that the thickness of the protective layer was 1.2 μm.

<Evaluation of image forming apparatus>
As the evaluation machine, “Kizhub C3850” manufactured by Konica Minolta Co., Ltd. basically having the configuration of FIG. 1 is used, and the photoconductors according to Examples 1 to 6 and Comparative Examples 1 to 4 are sequentially mounted on the evaluation machine. The image forming apparatus 100 according to Examples 1 to 6 and the image forming apparatuses according to Comparative Examples 1 to 4 are configured by adjusting the volume resistance of the charging roller and the amount of light on the surface of the charge removal light for each mounted photoconductor. Then, various evaluation tests were performed. The results of the evaluation test are shown in Table I below.

(Image streak defect evaluation test)
First, a half image with a predetermined density was output as an initial image, and the presence or absence of image streak defects in the direction of the photoreceptor axis was confirmed. Thereafter, an endurance test was conducted in which 500,000 character images were continuously printed on one side in an environment of 23 ° C. and 50% relative humidity (hereinafter referred to as RH). After the endurance test, a half-image with a predetermined density was output as the post-test image in the same manner as before the test, and the presence or absence of a color streak defect along the axial direction was evaluated. Evaluation was performed in the following four stages.
A: No image streak defect in the axial direction is found in the half image of the predetermined density. ○: One or more axial image streak defects having an axial length of less than 1 cm and a paper passage width of less than 1 mm are present in the predetermined density half image. Visible at a number of 4 or less.
Δ: Image streak defects in the axial direction having an axial length of less than 1 cm and a paper passage width of less than 1 mm are visually recognized in a number of 5 or more and 10 or less in a half image of a predetermined density.
X: Image stripe defects in the axial direction having an axial length of less than 1 cm and a paper passing width of less than 1 mm are visually recognized in a number of 11 or more in the half image of a predetermined density, or the axial length of 1 cm or more or the paper passing width. The image streak defect in the axial direction satisfying 1 mm or more is visually recognized by one or more numbers.

As a result of the evaluation, in Examples 1 to 6, both the initial image and the post-test image were evaluated as “good” or better.
In Comparative Examples 2 and 4, both the initial image and the post-test image were evaluated as ◎.
On the other hand, in Comparative Example 1 in which the protective layer did not contain the charge transport material (2) and the charge transport material (3) and in Comparative Example 3 where the protective layer was too thick, the evaluation of the image after the test was Δ or less.

(Evaluation test for wear resistance)
First, in an RH environment of 23 ° C. and 50%, an endurance test was performed in which a character image with an image ratio of 5% was continuously printed on one side of 2 million sheets. After the endurance test, an optical thickness gauge (Handy Lambda II Thickness, Using Spectra Corp., the thickness of the protective layer remaining on the surface of the photoreceptor was measured, and the presence or absence of density abnormality due to charging leakage was evaluated by the output of a half image. Evaluation was performed in the following three stages.
◎: The protective layer remains and a half-image with a predetermined density can be output. ○: The protective layer does not remain, but a half-image with a predetermined density can be output. X: The protective layer does not remain and the half-image with a predetermined density. There are areas where the density due to charging leakage is higher than the surrounding

As a result of the evaluation test, Examples 1 to 6, Comparative Example 1 and Comparative Example 3 were evaluated as ◯ or higher.
On the other hand, Comparative Example 2 in which the charge transport material (2) and the charge transport material (3) are too much and Comparative Example 4 in which the protective layer is too thin were evaluated as x.

(Evaluation test for memory defects)
In a RH environment of 23 ° C. and 50%, a belt-like solid image extending in the moving direction is printed on the half of the paper in the image forming apparatus, and the entire half on the opposite side of the moving direction is printed. A half image having a predetermined density was printed, and the density difference between a portion located on the extension of the solid image in the half image and other portions was evaluated. Evaluation was performed in the following three stages.
◎: No difference in density is observed in half image ○: A slight difference in density is observed in half image, but there is no practical problem ×: In the half image, the density difference is seen as a practical problem in the axial direction As a result, Examples 1-6, Comparative Example 1, Comparative Example 3, and Comparative Example 4 were evaluated as ◯ or higher.
On the other hand, Comparative Example 2 having too many charge transport materials (2) and charge transport materials (3) was evaluated as x.

As a result of the three types of evaluation tests, as shown in Table I, the image forming apparatus 100 according to Examples 1 to 6 has a good evaluation of ◯ or higher in any of the evaluation tests.
On the other hand, in any of the image forming apparatuses according to Comparative Examples 1 to 4, the evaluation of one type or two types of evaluation tests was Δ or less, and none of the three types of evaluation tests gave good evaluation.

DESCRIPTION OF SYMBOLS 100 Image forming apparatus 100A Apparatus main body 100B Image reader 10Y, 10M, 10C, 10Bk Image forming part 1Y, 1M, 1C, 1Bk Electrophotographic photoreceptor 11 Conductive support body 12 Intermediate layer 13 Photosensitive layer 13a Charge generation layer 13b Charge transport Layer 14 Protective layer 2Y, 2M, 2C, 2Bk Charging means 2a Charging roller 2b Voltage applying means 3Y, 3M, 3C, 3Bk Electrostatic latent image forming means 4Y, 4M, 4C, 4Bk Toner image forming means 5Y, 5M, 5C, 5Bk Primary transfer roller 5b Secondary transfer rollers 6Y, 6M, 6C, 6Bk Cleaning means 9Y, 9M, 9C, 9Bk Pre-exposure device 6b Cleaning means 7 Endless belt-shaped intermediate transfer body unit 8 Housing 20 Paper feed cassette 21 Paper feed conveyance Means 22A Intermediate roller 23 Registration roller 24 Fixing means 25 Paper discharge low Over 26 paper ejection tray 70 endless belt intermediate transfer member 71 roller 82L, 82R support rail P image support

Claims (5)

An image forming apparatus comprising at least an electrophotographic photosensitive member, a charging roller, a voltage applying unit, an electrostatic latent image forming unit, a toner image forming unit, and a transfer unit,
The voltage applying means is configured to apply a DC voltage to the charging roller;
The electrophotographic photoreceptor comprises at least a photosensitive layer and a protective layer in order from the conductive support side on the conductive support,
The photosensitive layer or the protective layer contains a compound having a structure represented by the following general formula (1) as a charge transport material,
It contains at least one of the compound having the structure represented by the following general formula (2) and the compound having the structure represented by the following general formula (3), and the ratio of the total amount is represented by the following general formula (1) ), A compound having a structure represented by the following general formula (2), and a total metric of a compound having a structure represented by the following general formula (3). It is contained so that it is in the range of 05-0.15 mass%,
The protective layer contains a composition obtained by curing a polymerizable compound and metal oxide particles, and is formed to have a layer thickness in a range of 1.5 to 2.8 μm. Image forming apparatus.

(However, R ₁ , R ₂ and R ₃ in the general formula (1), the general formula (2) and the general formula (3) each independently represent a hydrogen atom, an alkyl group or an alkoxy group. l and n each independently represents an integer of 1 to 5, and m represents an integer of 1 to 4. Note that l, m, and n are integers of 2 or more. In this case, R ₁ , R ₂ and R ₃ may be the same or different.)   The image forming apparatus according to claim 1, wherein the charge transport material is contained in the protective layer. The volume resistance of the charging roller when a voltage of 500 V is applied from the voltage applying means is in the range of 1.0 × 10 ^{4 to} 1.0 × 10 ⁶ Ω. The image forming apparatus according to claim 2.   Discharge light with a wavelength of 660 nm is applied to the surface of the electrophotographic photosensitive member on the surface of the electrophotographic photosensitive member in the moving direction side of the electrophotographic photosensitive member with respect to the transfer unit and in front of the charging roller in the moving direction of the electrophotographic photosensitive member. The image forming apparatus according to any one of claims 1 to 3, further comprising a pre-exposure device that irradiates the light amount on the surface of the electrophotographic photosensitive member so as to be 100 μW or less. A process cartridge for use in the image forming apparatus according to any one of claims 1 to 4,
Comprising the electrophotographic photoreceptor,
A process cartridge configured to be detachable from the image forming apparatus.

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