JP2023144994A - Image forming apparatus, and unit for image forming apparatus - Google Patents

Abstract

An object of the present invention is to provide an image forming apparatus having excellent electrical properties and abrasion resistance of an inorganic protective layer in an electrophotographic photoreceptor. The present invention has a conductive substrate, a photosensitive layer, and an inorganic protective layer containing a metal element M, oxygen O, and hydrogen H in this order, and in a layer constituting the surface of the inorganic protective layer, the oxygen O and the an electrophotographic photoreceptor having an elemental composition ratio (oxygen O/metal element M) with a metal element M of 1.3 or more and 1.5 or less; a contact-type charging member that charges the surface of the electrophotographic photoreceptor; A charging device having an AC voltage application unit that applies an AC voltage to a contact type charging member, an electrostatic image forming device that forms an electrostatic image on the surface of the charged electrophotographic photoreceptor, and an electrostatic image developer. a developing device that supplies a toner image to develop the electrostatic charge image formed on the surface of the electrophotographic photoreceptor as a toner image; and a developing device that transfers the toner image formed on the surface of the electrophotographic photoreceptor onto the surface of a recording medium. An image forming apparatus comprising: a transfer device; [Selection diagram] Figure 1

Description

The present invention relates to an image forming apparatus and a unit for an image forming apparatus.

Image formation by electrophotography involves, for example, charging the surface of a photoreceptor, forming an electrostatic image on the surface of the photoreceptor according to image information, and then developing this electrostatic image with a developer containing toner. This is done by developing to form a toner image, and transferring and fixing this toner image onto the surface of a recording medium.

Here, Patent Document 1 states, ``In an electrophotographic apparatus having an electrophotographic photoreceptor, a toner supply member, and a charge imparting member, or a process cartridge that is detachably attached to the main body of the electrophotographic apparatus, the outer surface of the electrophotographic photoreceptor is has two protective layers, each of which contains metal or metal oxide particles and a binder resin, and the ratio of the metal or metal oxide particles contained in the protective layer 1 on the photosensitive layer side and the protective layer 1 An electrophotographic photoreceptor characterized in that the relationship of the ratios contained in the protective layer 2 laminated thereon satisfies the following formula (1).''
P1>P2 Formula (1)
P1 Weight % of metal or metal oxide particles contained in protective layer 1
P2 Weight % of metal or metal oxide particles contained in protective layer 2

Japanese Patent Application Publication No. 2004-133044

An object of the present invention is to provide an electrophotographic photoreceptor having a conductive substrate, a photosensitive layer, and an inorganic protective layer containing a metal element M, oxygen O, and hydrogen H in this order, and a charging member that charges the surface of the electrophotographic photoreceptor. an electrostatic charge image forming device that forms an electrostatic charge image on the surface of a charged electrophotographic photoreceptor; In an image forming apparatus comprising a developing device that develops an image as a toner image and a transfer device that transfers the toner image formed on the surface of an electrophotographic photoreceptor to the surface of a recording medium, forming the surface of an inorganic protective layer. Compared to the case where the elemental composition ratio of oxygen O and metal element M in the layer (oxygen O/metal element M) is less than 1.3, the electrical properties and abrasion resistance of the inorganic protective layer in the electrophotographic photoreceptor are improved. The objective is to provide an excellent image forming apparatus.

Means for solving the above problems include the following aspects.
<1>
The oxygen O and the metal element in a layer comprising a conductive substrate, a photosensitive layer, and an inorganic protective layer containing a metal element M, oxygen O, and hydrogen H in this order, and forming a surface of the inorganic protective layer. An electrophotographic photoreceptor having an elemental composition ratio (oxygen O/metal element M) with M of 1.3 or more and 1.5 or less;
a charging device having a contact-type charging member that charges the surface of the electrophotographic photoreceptor; and an AC voltage application unit that applies an AC voltage to the contact-type charging member;
an electrostatic image forming device that forms an electrostatic image on the surface of the charged electrophotographic photoreceptor;
a developing device that supplies an electrostatic image developer to develop the electrostatic image formed on the surface of the electrophotographic photoreceptor as a toner image;
a transfer device that transfers the toner image formed on the surface of the electrophotographic photoreceptor to the surface of a recording medium;
An image forming apparatus comprising:
<2>
<1>, wherein the elemental composition ratio (oxygen O/metal element M) of the oxygen O and the metal element M in the layer constituting the surface of the inorganic protective layer is 1.4 or more and 1.5 or less. Image forming device.
<3>
The inorganic protective layer is a layer constituting the surface of the inorganic protective layer, in which the elemental composition ratio of the oxygen O and the metal element M (oxygen O/metal element M) is 1.3 or more and less than 1.5. The image forming apparatus according to <1> or <2>, which is a single layer body.
<4>
The image forming device according to <3>, wherein the monolayer of the layer constituting the surface of the inorganic protective layer has a thickness of 0.5 μm or more and 1.0 μm or less.
<5>
Any one of <1> to <4>, wherein the peak-to-peak voltage V _pp of the AC voltage applied to the contact-type charging member by the AC voltage applying unit is 350 V or less and 4000 V or less, and the frequency is 100 Hz or more. The image forming apparatus described in .
<6>
The image forming apparatus according to <5>, wherein the peak-to-peak voltage _Vpp is 800V or more and 1500V or less, and the frequency is 2500Hz or more.
<7>
The charging member is provided upstream in the rotational direction of the electrophotographic photoreceptor than the contact charging member, and includes a non-contact charging member that charges the surface of the electrophotographic photoreceptor, and a non-contact charging member that charges the surface of the electrophotographic photoreceptor. The image forming apparatus according to any one of <1> to <4>, further comprising a DC voltage applying section that applies a DC voltage to the charging member.
<8>
The peak-to-peak voltage V _pp of the AC voltage applied to the contact-type charging member by the AC voltage applying unit is 1000 V or more and 4000 V or less, and the frequency is 2500 Hz or more,
The image forming apparatus according to <7>, wherein a voltage V of the DC voltage applied to the non-contact charging member by the DC voltage applying section is 600V or more and 1000V or less.
<9>
The image forming apparatus according to any one of <1> to <8>, wherein the inorganic protective layer has a light transmittance of 90% or more.
<10>
The oxygen O and the metal element in a layer comprising a conductive substrate, a photosensitive layer, and an inorganic protective layer containing a metal element M, oxygen O, and hydrogen H in this order, and forming a surface of the inorganic protective layer. An electrophotographic photoreceptor having an elemental composition ratio (oxygen O/metal element M) with M of 1.3 or more and 1.5 or less;
a charging device having a contact-type charging member that charges the surface of the electrophotographic photoreceptor; and an AC voltage application unit that applies an AC voltage to the contact-type charging member;
An image forming apparatus unit comprising:

According to the invention according to <1>, an electrophotographic photoreceptor having a conductive substrate, a photosensitive layer, and an inorganic protective layer containing a metal element M, oxygen O, and hydrogen H in this order; A charging device having a charging member that charges, an electrostatic image forming device that forms an electrostatic image on the surface of a charged electrophotographic photoreceptor, and an electrostatic image developer that supplies an electrostatic image developer to form an electrostatic image on the surface of the electrophotographic photoreceptor. In an image forming apparatus that includes a developing device that develops the electrostatic charge image formed on the surface of the electrophotographic photoreceptor as a toner image, and a transfer device that transfers the toner image formed on the surface of the electrophotographic photoreceptor to the surface of the recording medium, an inorganic protective layer is used. Compared to a case where the elemental composition ratio of oxygen O and metal element M (oxygen O/metal element M) in the layer constituting the surface is less than 1.3, the electrical properties and inorganic protective layer of the electrophotographic photoreceptor are improved. An image forming apparatus with excellent wear resistance is provided.

According to the invention according to <2>, the electrical properties and inorganic An image forming apparatus is provided in which a protective layer has excellent abrasion resistance.

According to the invention according to <3>, the inorganic protective layer has an elemental composition ratio of oxygen O and metal element M (oxygen O/metal element M) of 1.3 or more and less than 1.5. An image forming apparatus is provided in which the electrical properties and the abrasion resistance of an inorganic protective layer in an electrophotographic photoreceptor are superior to those in the case of a laminate including layers constituting the surface.

According to the invention according to <4>, the electrical properties and the inorganic protective layer in the electrophotographic photoreceptor are improved compared to the case where the thickness of the monolayer of the layer constituting the surface of the inorganic protective layer is less than 0.5 μm. An image forming apparatus having excellent abrasion resistance is provided.

According to the invention according to <5>, compared to the case where the peak-to-peak voltage _Vpp of the AC voltage applied to the tactile charging member by the AC voltage application unit is less than 350V or more than 4000V, or the frequency is less than 100Hz, An image forming apparatus is provided that has excellent electrical properties and abrasion resistance of an inorganic protective layer in an electrophotographic photoreceptor.
According to the invention according to <6>, compared to the case where the peak-to-peak voltage _Vpp of the AC voltage applied to the tactile charging member by the AC voltage application unit is less than 800V or more than 1500V, or the frequency is less than 2500Hz, An image forming apparatus is provided that has excellent electrical properties and abrasion resistance of an inorganic protective layer in an electrophotographic photoreceptor.

According to the invention according to <7>, an electrophotographic photoreceptor having a conductive substrate, a photosensitive layer, and an inorganic protective layer containing a metal element M, oxygen O, and hydrogen H in this order; A charging device having a charging member that charges, an electrostatic image forming device that forms an electrostatic image on the surface of a charged electrophotographic photoreceptor, and an electrostatic image developer that supplies an electrostatic image developer to form an electrostatic image on the surface of the electrophotographic photoreceptor. In an image forming apparatus that includes a developing device that develops the electrostatic charge image formed on the surface of the electrophotographic photoreceptor as a toner image, and a transfer device that transfers the toner image formed on the surface of the electrophotographic photoreceptor to the surface of the recording medium, an inorganic protective layer is used. Compared to the case where the elemental composition ratio of oxygen O and metal element M (oxygen O/metal element M) in the layer constituting the surface is less than 1.3, contact charging member and non-contact charging member are Provided is an image forming apparatus having an electrophotographic photoreceptor having excellent electrical properties and abrasion resistance of an inorganic protective layer.
According to the invention according to <8>, the peak-to-peak voltage V _pp of the AC voltage applied to the contact-type charging member by the AC voltage application unit is less than 1000 V or more than 4000 V, or the frequency is less than 2500 Hz, or the DC voltage application unit This provides an image forming apparatus that has superior electrical properties and abrasion resistance of an inorganic protective layer in an electrophotographic photoreceptor, compared to cases where the voltage V is less than 600 V or more than 1000 V in the DC voltage applied to a non-contact charging member. provided.

According to the invention according to <9>, the electrical properties and abrasion resistance of the inorganic protective layer in the electrophotographic photoreceptor are improved compared to the case where the light transmittance of the layer constituting the surface of the inorganic protective layer is less than 90%. An image forming apparatus with excellent performance is provided.

According to the invention according to <10>, there is provided an electrophotographic photoreceptor having a conductive substrate, a photosensitive layer, and an inorganic protective layer containing a metal element M, oxygen O, and hydrogen H in this order, and a surface of the electrophotographic photoreceptor. In an image forming unit comprising a charging device having a charging member that charges, the elemental composition ratio of oxygen O and metal element M (oxygen O/metal element M) in the layer constituting the surface of the inorganic protective layer is 1. An image forming unit in an electrophotographic photoreceptor having excellent electrical properties and excellent abrasion resistance of an inorganic protective layer is provided, compared to a case where the ratio is less than .3.

1 is a schematic configuration diagram showing an example of an image forming apparatus according to an embodiment. FIG. 3 is a schematic configuration diagram showing another example of the image forming apparatus according to the present embodiment. 1 is a schematic diagram showing an example of a film forming apparatus used for forming an inorganic protective layer of an electrophotographic photoreceptor in this embodiment. 1 is a schematic diagram showing an example of a plasma generation device used for forming an inorganic protective layer of an electrophotographic photoreceptor in this embodiment. FIG. 2 is a schematic cross-sectional view showing an example of a layer structure of an electrophotographic photoreceptor in an image forming apparatus according to the present embodiment. FIG. 3 is a schematic cross-sectional view showing another example of the layer structure of the electrophotographic photoreceptor in the image forming apparatus according to the present embodiment.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment which is an example of this invention is described in detail. These descriptions and examples are illustrative of the invention and are not intended to limit it.

In this specification, a numerical range indicated using "-" indicates a range that includes the numerical values written before and after "-" as the minimum and maximum values, respectively.
In the numerical ranges described step by step in this specification, the upper limit value or lower limit value described in one numerical range may be replaced with the upper limit value or lower limit value of another numerical range described step by step. good. Furthermore, in the numerical ranges described in this disclosure, the upper limit or lower limit of the numerical range may be replaced with the values shown in the Examples.

In this specification, the term "process" is used not only to refer to an independent process, but also to include any process that is not clearly distinguishable from other processes as long as the intended purpose of the process is achieved. .

When embodiments are described in this specification with reference to drawings, the configuration of the embodiments is not limited to the configuration shown in the drawings. Furthermore, the sizes of the members in each figure are conceptual, and the relative size relationships between the members are not limited thereto.

In this specification, each component may contain multiple types of corresponding substances. When referring to the amount of each component in the composition in this disclosure, if there are multiple types of substances corresponding to each component in the composition, unless otherwise specified, the amount of each component in the composition is means the total amount of substance.

<Image forming device>
The image forming apparatus according to the present embodiment includes an electrophotographic photoreceptor (hereinafter also simply referred to as "photoreceptor"), a charging device that charges the surface of the photoreceptor, and an electrostatic charge image that forms an electrostatic charge image on the surface of the charged photoreceptor. An electrostatic image forming device, a developing device that supplies an electrostatic image developer to develop the electrostatic image formed on the surface of the photoconductor as a toner image, and a developing device that records the toner image formed on the surface of the photoconductor. A transfer device that transfers images onto the surface of a medium.
The photoreceptor has a conductive substrate, a photosensitive layer, and an inorganic protective layer containing metal element M, oxygen O, and hydrogen H in this order, and oxygen O and metal in the layer constituting the surface of the inorganic protective layer. The elemental composition ratio (oxygen O/metal element M) with element M is 1.3 or more and 1.5 or less.
The charging device includes a contact-type charging member that charges the surface of the electrophotographic photoreceptor, and an AC voltage applying section that applies an AC voltage to the contact-type charging member.

Here, the image forming apparatus according to the present embodiment is a direct transfer type device that directly transfers a toner image formed on the surface of a photoconductor to a recording medium; Intermediate transfer type device that performs primary transfer on the surface of the photoreceptor and secondary transfer of the toner image transferred to the surface of the intermediate transfer member onto the surface of the recording medium; A well-known image forming apparatus, such as an apparatus equipped with a static eliminator that removes static electricity by irradiating the image, can be applied.
In the case of an intermediate transfer type device, the transfer device includes, for example, an intermediate transfer body on which a toner image is transferred, and a primary transfer device that primarily transfers the toner image formed on the surface of a photoreceptor onto the surface of the intermediate transfer body. and a secondary transfer device that secondary transfers the toner image transferred to the surface of the intermediate transfer member to the surface of the recording medium.

Note that in the image forming apparatus according to the present embodiment, a portion including at least the photoreceptor and the charging device constitutes a unit for the image forming apparatus, and has a cartridge structure (process cartridge) that is detachable from the image forming apparatus. Good too.

Due to the above configuration, the image forming apparatus according to the present embodiment has excellent electrical properties and abrasion resistance of the inorganic protective layer on the photoreceptor. The reason is assumed to be as follows.

In the photoreceptor, the inorganic protective layer containing the metal element M, oxygen O, and hydrogen H, which functions as an electron transport layer, performs surface electron injection to obtain charging properties, and photoelectric conversion function and electron transport to obtain electrical properties. It is necessary to have the function and the function of.
In order to inject electrons into the inorganic protective layer on the surface of the photoreceptor, the resistance of the layer constituting the surface of the inorganic protective layer is made low.
However, lowering the resistance of the layer constituting the surface of the inorganic protective layer requires increasing the amount of metal elements in order to lower the surface resistance, resulting in a decrease in light transmittance and a decline in photoelectric conversion function and electron transport function. As a result, the electrical characteristics of the photoreceptor are degraded. Furthermore, the abrasion resistance of the inorganic protective layer decreases.

Therefore, in this embodiment, the elemental composition ratio of oxygen O and metal element M (oxygen O/metal element M) in the layer constituting the surface of the inorganic protective layer of the photoreceptor is set to 1.3 or more and 1.5 or less. do. This improves abrasion resistance as well as photoelectric conversion function and electron transport function.
On the other hand, as the charging device, a charging device is used that includes a contact-type charging member that charges the surface of the photoreceptor and an AC voltage applying section that applies an AC voltage to the contact-type charging member. Thereby, the charging member injects electrons into the surface of the photoreceptor, that is, into the inorganic protective layer. Thereby, charging characteristics are also ensured.

From the above, it is presumed that the image forming apparatus according to the present embodiment has excellent electrical properties and abrasion resistance of the inorganic protective layer in the photoreceptor.

Next, the configuration of the image forming apparatus according to this embodiment will be explained in detail.

An example of an image forming apparatus according to this embodiment will be shown below, but the present invention is not limited thereto. Note that the main parts shown in the figure will be explained, and the explanation of the others will be omitted.

FIG. 1 is a schematic configuration diagram showing an example of an image forming apparatus according to this embodiment.
As shown in FIG. 1, the image forming apparatus 10 according to the present embodiment is provided with, for example, a photoreceptor 12. The photoreceptor 12 has a cylindrical shape and is connected to a drive unit 27 such as a motor via a drive force transmission member (not shown) such as a gear. Rotationally driven. In the example shown in FIG. 1, it is rotationally driven in the direction of arrow A.

Around the photoreceptor 12, for example, a charging device 15 (an example of a charging device), an electrostatic image forming device 16 (an example of an electrostatic image forming device), a developing device 18 (an example of a developing device), a transfer device 31 ( A transfer device (an example of a transfer device), a cleaning device 22 (an example of a cleaning device), and a static eliminator 24 are arranged in this order along the rotational direction of the photoreceptor 12. The image forming apparatus 10 is also provided with a fixing device 26 having a fixing member 26A and a pressure member 26B disposed in contact with the fixing member 26A. The image forming apparatus 10 also includes a control device 36 that controls the operation of each device (each part). Note that a unit including the photoreceptor 12, charging device 15, electrostatic image forming device 16, developing device 18, transfer device 31, and cleaning device 22 corresponds to an image forming unit.

In the image forming apparatus 10, at least the photoreceptor 12 may be provided as a process cartridge integrated with other apparatuses.

The details of each device (each part) of the image forming apparatus 10 will be described below.

[Electrophotographic photoreceptor]
A photoreceptor has a photosensitive layer and an inorganic protective layer in this order on a conductive substrate.
The photosensitive layer may be a single-layer type photosensitive layer in which a charge generation material and a charge transport material are contained in the same photosensitive layer to have integrated functions, or a laminated layer having a charge generation layer and a charge transport layer with separate functions. It may also be a type photosensitive layer.
When the photosensitive layer is a laminated type photosensitive layer, the order of the charge generation layer and the charge transport layer is not particularly limited, but the photoreceptor has the charge generation layer, the charge transport layer, and the inorganic protective layer on the conductive substrate. A configuration having the elements in this order is preferable. Further, the photoreceptor may include layers other than these layers.

FIG. 5 is a schematic cross-sectional view showing an example of the layer structure of the photoreceptor in the image forming apparatus according to the present embodiment. A photoreceptor 107A shown in FIG. 5 has a structure in which a subbing layer 101 is provided on a conductive substrate 104, and a charge generation layer 102, a charge transport layer 103, and an inorganic protective layer 106 are sequentially formed thereon. . In the photoreceptor 107A, a photosensitive layer 105 is configured with a charge generation layer 102 and a charge transport layer 103 whose functions are separated.

Further, FIG. 6 is a schematic cross-sectional view showing another example of the layer structure of the photoreceptor in the image forming apparatus according to the present embodiment. A photoreceptor 107B shown in FIG. 6 has a structure in which a subbing layer 101 is provided on a conductive substrate 104, and a photosensitive layer 105 and an inorganic protective layer 106 are sequentially formed. In the photoreceptor 107B, a single-layer type photosensitive layer is constructed in which a charge generating material and a charge transporting material are contained in the same photosensitive layer 105 to have integrated functions.
Note that the photoreceptor in this embodiment may or may not be provided with the subbing layer 101.

The details of the photoreceptor in this embodiment will be described below, but the reference numerals will be omitted.

(Conductive substrate)
Examples of the conductive substrate include metal plates, metal drums, and metal belts containing metals (aluminum, copper, zinc, chromium, nickel, molybdenum, vanadium, indium, gold, platinum, etc.) or alloys (stainless steel, etc.). can be mentioned. Examples of conductive substrates include paper, resin films, belts, etc. coated with, vapor-deposited, or laminated with conductive compounds (e.g., conductive polymers, indium oxide, etc.), metals (e.g., aluminum, palladium, gold, etc.), or alloys. can also be mentioned. Here, "conductivity" means that the volume resistivity is less than 10 ¹³ Ωcm.

When the electrophotographic photoreceptor is used in a laser printer, the surface of the conductive substrate has a centerline average roughness Ra of 0.04 μm or more and 0.5 μm for the purpose of suppressing interference fringes that occur when irradiated with laser light. It is preferable that the surface be roughened. Note that when incoherent light is used as a light source, surface roughening to prevent interference fringes is not particularly necessary, but it is suitable for longer life because it suppresses the occurrence of defects due to unevenness on the surface of the conductive substrate.

Examples of surface roughening methods include wet honing, which is performed by suspending an abrasive in water and spraying it on the support; centerless grinding, which involves pressing a conductive substrate against a rotating grindstone and grinding it continuously; Examples include anodizing treatment.

The surface roughening method involves dispersing conductive or semiconductive powder in a resin to form a layer on the surface of the conductive substrate, without roughening the surface of the conductive substrate. Another example is a method of roughening the surface using particles dispersed in the layer.

Surface roughening treatment by anodic oxidation is a method of forming an oxide film on the surface of a conductive substrate by anodic oxidation in an electrolyte solution using a metal (for example, aluminum) conductive substrate as an anode. Examples of the electrolyte solution include sulfuric acid solution and oxalic acid solution. However, the porous anodic oxide film formed by anodic oxidation is chemically active as it is, is easily contaminated, and has large resistance fluctuations depending on the environment. Therefore, for a porous anodic oxide film, the micropores of the oxide film are blocked by volume expansion caused by a hydration reaction with pressurized steam or boiling water (metal salts such as nickel may be added) to achieve more stable hydrated oxidation. It is preferable to perform a sealing process to convert the material into a material.

The thickness of the anodic oxide film is preferably, for example, 0.3 μm or more and 15 μm or less. When the film thickness is within the above range, barrier properties against injection tend to be exhibited, and increases in residual potential due to repeated use tend to be suppressed.

The conductive substrate may be treated with an acidic treatment liquid or treated with boehmite.
The treatment with the acidic treatment liquid is carried out, for example, as follows. First, an acidic treatment solution containing phosphoric acid, chromic acid, and hydrofluoric acid is prepared. The blending ratio of phosphoric acid, chromic acid, and hydrofluoric acid in the acidic treatment solution is, for example, phosphoric acid in the range of 10% by mass to 11% by mass, chromic acid in the range of 3% to 5% by mass, and hydrofluoric acid in the range of 3% to 5% by mass. The range is 0.5% by mass or more and 2% by mass or less, and the overall concentration of these acids is preferably in the range of 13.5% by mass or more and 18% by mass or less. The treatment temperature is preferably, for example, 42°C or higher and 48°C or lower. The thickness of the coating is preferably 0.3 μm or more and 15 μm or less.

The boehmite treatment is performed, for example, by immersion in pure water at 90° C. or higher and 100° C. or lower for 5 minutes to 60 minutes, or by contacting with heated steam at 90° C. or higher and 120° C. or lower for 5 minutes to 60 minutes. The thickness of the coating is preferably 0.1 μm or more and 5 μm or less. This can be further anodized using an electrolyte solution with low film solubility, such as adipic acid, boric acid, borate, phosphate, phthalate, maleate, benzoate, tartrate, or citrate. good.

(subbing layer)
The subbing layer is, for example, a layer containing inorganic particles and a binder resin.

Examples of the inorganic particles include inorganic particles having a powder resistance (volume resistivity) of 10 ² Ωcm or more and 10 ¹¹ Ωcm or less.
Among these, as the inorganic particles having the above-mentioned resistance value, metal oxide particles such as tin oxide particles, titanium oxide particles, zinc oxide particles, and zirconium oxide particles are preferable, and zinc oxide particles are particularly preferable.

The specific surface area of the inorganic particles measured by the BET method is preferably 10 m ² /g or more, for example.
The volume average particle diameter of the inorganic particles is, for example, 50 nm or more and 2000 nm or less (preferably 60 nm or more and 1000 nm or less).

The content of the inorganic particles is, for example, preferably 10% by mass or more and 80% by mass or less, more preferably 40% by mass or more and 80% by mass or less, based on the binder resin.

The inorganic particles may be surface-treated. Two or more types of inorganic particles with different surface treatments or different particle sizes may be used as a mixture.

Examples of the surface treatment agent include silane coupling agents, titanate coupling agents, aluminum coupling agents, and surfactants. In particular, silane coupling agents are preferred, and silane coupling agents having an amino group are more preferred.

Examples of the silane coupling agent having an amino group include 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-amino Examples include, but are not limited to, propylmethyldimethoxysilane, N,N-bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane, and the like.

Two or more types of silane coupling agents may be used in combination. For example, a silane coupling agent having an amino group and another silane coupling agent may be used together. Examples of other silane coupling agents include vinyltrimethoxysilane, 3-methacryloxypropyl-tris(2-methoxyethoxy)silane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and 3-glyoxypropyl-tris(2-methoxyethoxy)silane. Sidoxypropyltrimethoxysilane, vinyltriacetoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-( Examples include, but are not limited to, aminoethyl)-3-aminopropylmethyldimethoxysilane, N,N-bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane, and 3-chloropropyltrimethoxysilane. It's not a thing.

The surface treatment method using the surface treatment agent may be any known method, and may be either a dry method or a wet method.

The amount of the surface treatment agent to be treated is preferably, for example, 0.5% by mass or more and 10% by mass or less based on the inorganic particles.

Here, it is preferable for the undercoat layer to contain an electron-accepting compound (acceptor compound) together with inorganic particles, from the viewpoint of improving long-term stability of electrical properties and carrier blocking properties.

Examples of electron-accepting compounds include quinone compounds such as chloranil and bromoanil; tetracyanoquinodimethane compounds; 2,4,7-trinitrofluorenone, 2,4,5,7-tetranitro-9-fluorenone, etc. Fluorenone compound; 2-(4-biphenyl)-5-(4-t-butylphenyl)-1,3,4-oxadiazole, 2,5-bis(4-naphthyl)-1,3,4- Oxadiazole compounds such as oxadiazole, 2,5-bis(4-diethylaminophenyl)-1,3,4oxadiazole; xanthone compounds; thiophene compounds; 3,3',5,5'tetra- Examples include electron transporting substances such as diphenoquinone compounds such as t-butyldiphenoquinone;
In particular, as the electron-accepting compound, a compound having an anthraquinone structure is preferred. As the compound having an anthraquinone structure, for example, a hydroxyanthraquinone compound, an aminoanthraquinone compound, an aminohydroxyanthraquinone compound, etc. are preferable, and specifically, for example, anthraquinone, alizarin, quinizarin, anthralphine, purpurin, etc. are preferable.

The electron-accepting compound may be contained in the undercoat layer in a dispersed manner with the inorganic particles, or may be contained in a state attached to the surface of the inorganic particles.

Examples of the method for attaching the electron-accepting compound to the surface of the inorganic particles include a dry method and a wet method.

In the dry method, for example, while stirring inorganic particles with a mixer with a large shearing force, an electron-accepting compound is dropped directly or dissolved in an organic solvent, and the electron-accepting compound is sprayed with dry air or nitrogen gas. This is a method of adhering to the surface of inorganic particles. When dropping or spraying the electron-accepting compound, it is preferable to do so at a temperature below the boiling point of the solvent. After dropping or spraying the electron-accepting compound, baking may be performed at a temperature of 100° C. or higher. There are no particular restrictions on the baking temperature and time as long as the electrophotographic properties can be obtained.

In the wet method, for example, an electron-accepting compound is added while dispersing inorganic particles in a solvent using stirring, ultrasonic waves, a sand mill, an attritor, a ball mill, etc., and after stirring or dispersion, the solvent is removed and the electron-accepting compound is added. This is a method in which a receptive compound is attached to the surface of an inorganic particle. The solvent is removed by, for example, filtration or distillation. After removing the solvent, baking may be further performed at 100° C. or higher. There are no particular limitations on the baking temperature and time as long as the electrophotographic properties can be obtained. In the wet method, the water contained in the inorganic particles may be removed before adding the electron-accepting compound, examples of which include removing the water while stirring and heating it in a solvent, and removing it by azeotroping with the solvent. Can be mentioned.

Note that the electron-accepting compound may be attached before or after the inorganic particles are subjected to surface treatment with a surface treatment agent, or may be carried out simultaneously with the attachment of the electron-accepting compound and the surface treatment with the surface treatment agent.

The content of the electron-accepting compound is, for example, preferably 0.01% by mass or more and 20% by mass or less, and preferably 0.01% by mass or more and 10% by mass or less based on the inorganic particles.

Examples of the binder resin used in the undercoat layer include acetal resin (for example, polyvinyl butyral), polyvinyl alcohol resin, polyvinyl acetal resin, casein resin, polyamide resin, cellulose resin, gelatin, polyurethane resin, polyester resin, and unsaturated polyester. Resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinyl acetate resin, vinyl chloride-vinyl acetate-maleic anhydride resin, silicone resin, silicone-alkyd resin, urea resin, phenol resin, phenol-formaldehyde resin, melamine resin, Known materials include known polymer compounds such as urethane resins, alkyd resins, and epoxy resins; zirconium chelate compounds; titanium chelate compounds; aluminum chelate compounds; titanium alkoxide compounds; organic titanium compounds; and silane coupling agents.
Examples of the binder resin used in the undercoat layer include charge transporting resins having a charge transporting group, conductive resins (eg, polyaniline, etc.), and the like.

Among these, resins that are insoluble in the coating solvent of the upper layer are suitable as the binder resin for the undercoat layer, and in particular, urea resins, phenol resins, phenol-formaldehyde resins, melamine resins, urethane resins, and unsaturated polyesters are suitable. Thermosetting resins such as resins, alkyd resins, and epoxy resins; at least one resin selected from the group consisting of polyamide resins, polyester resins, polyether resins, methacrylic resins, acrylic resins, polyvinyl alcohol resins, and polyvinyl acetal resins; Resins obtained by reaction with curing agents are preferred.
When using a combination of two or more of these binder resins, the mixing ratio is determined as necessary.

The undercoat layer may contain various additives to improve electrical properties, environmental stability, and image quality.
Examples of additives include known materials such as polycyclic condensation type, azo type electron transport pigments, zirconium chelate compounds, titanium chelate compounds, aluminum chelate compounds, titanium alkoxide compounds, organic titanium compounds, and silane coupling agents. It will be done. The silane coupling agent is used for surface treatment of inorganic particles as described above, but it may also be added to the undercoat layer as an additive.

Examples of the silane coupling agent as an additive include vinyltrimethoxysilane, 3-methacryloxypropyl-tris(2-methoxyethoxy)silane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3- Glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2- Examples include (aminoethyl)-3-aminopropylmethyldimethoxysilane, N,N-bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane, and 3-chloropropyltrimethoxysilane.

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

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

Examples of the aluminum chelate compound include aluminum isopropylate, monobutoxyaluminum diisopropylate, aluminum butyrate, diethylacetoacetate aluminum diisopropylate, aluminum tris (ethylacetoacetate), and the like.

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

The undercoat layer preferably has a Vickers hardness of 35 or more.
The surface roughness (ten-point average roughness) of the undercoat layer ranges from 1/(4n) (n is the refractive index of the upper layer) to 1/2 of the exposure laser wavelength λ used to suppress moiré images. It is good to have it adjusted to
Resin particles or the like may be added to the undercoat layer to adjust the surface roughness. Examples of the resin particles include silicone resin particles and crosslinked polymethyl methacrylate resin particles. Further, the surface of the undercoat layer may be polished to adjust the surface roughness. Examples of the polishing method include buffing, sandblasting, wet honing, and grinding.

There are no particular restrictions on the formation of the undercoat layer, and well-known formation methods may be used. and heat as necessary.

As the solvent for preparing the coating solution for forming the undercoat layer, known organic solvents such as alcohol solvents, aromatic hydrocarbon solvents, halogenated hydrocarbon solvents, ketone solvents, ketone alcohol solvents, and ether solvents can be used. Examples include solvents and ester solvents.
Specific examples of these solvents include methanol, ethanol, n-propanol, iso-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, ethyl acetate, Common organic solvents include n-butyl acetate, dioxane, tetrahydrofuran, methylene chloride, chloroform, chlorobenzene, and toluene.

Examples of methods for dispersing inorganic particles when preparing a coating solution for forming an undercoat layer include known methods such as a roll mill, a ball mill, a vibrating ball mill, an attriter, a sand mill, a colloid mill, and a paint shaker.

Examples of methods for applying the coating solution for forming an undercoat layer onto the conductive substrate include blade coating, wire bar coating, spray coating, dip coating, bead coating, air knife coating, and curtain coating. For example, conventional methods such as

The thickness of the undercoat layer is, for example, preferably 15 μm or more, more preferably 20 μm or more and 50 μm or less.

(middle class)
Although not shown, an intermediate layer may be further provided between the undercoat layer and the photosensitive layer.
The intermediate layer is, for example, a layer containing resin. Examples of the resin used for the intermediate layer include acetal resin (e.g., polyvinyl butyral), polyvinyl alcohol resin, polyvinyl acetal resin, casein resin, polyamide resin, cellulose resin, gelatin, polyurethane resin, polyester resin, methacrylic resin, acrylic resin, Examples include polymeric compounds such as polyvinyl chloride resin, polyvinyl acetate resin, vinyl chloride-vinyl acetate-maleic anhydride resin, silicone resin, silicone-alkyd resin, phenol-formaldehyde resin, and melamine resin.
The intermediate layer may be a layer containing an organometallic compound. Examples of the organometallic compound used in the intermediate layer include organometallic compounds containing metal atoms such as zirconium, titanium, aluminum, manganese, and silicon.
The compounds used in these intermediate layers may be used alone or as a mixture or polycondensate of a plurality of compounds.

Among these, the intermediate layer is preferably a layer containing an organometallic compound containing a zirconium atom or a silicon atom.

There are no particular restrictions on the formation of the intermediate layer, and well-known formation methods may be used. This is done by heating according to the conditions.
As a coating method for forming the intermediate layer, conventional methods such as dip coating, push-up coating, wire bar coating, spray coating, blade coating, knife coating, and curtain coating can be used.

The thickness of the intermediate layer is, for example, preferably set in a range of 0.1 μm or more and 3 μm or less. Note that the intermediate layer may be used as a subbing layer.

(charge generation layer)
The charge generation layer is, for example, a layer containing a charge generation material and a binder resin. Further, the charge generation layer may be a deposited layer of a charge generation material. The vapor-deposited layer of charge-generating material is suitable when using a non-coherent light source such as a light emitting diode (LED) or an electro-luminescence (EL) image array.

Examples of the charge generating material include azo pigments such as bisazo and trisazo; condensed aromatic pigments such as dibromoanthanthrone; perylene pigments; pyrrolopyrrole pigments; phthalocyanine pigments; zinc oxide; and trigonal selenium.

Among these, it is preferable to use a metal phthalocyanine pigment or a metal-free phthalocyanine pigment as the charge-generating material in order to make it compatible with laser exposure in the near-infrared region. Specifically, for example, hydroxygallium phthalocyanine; chlorogallium phthalocyanine; dichlorotin phthalocyanine; and titanyl phthalocyanine are more preferable.

On the other hand, in order to be compatible with laser exposure in the near-ultraviolet region, charge-generating materials include condensed aromatic pigments such as dibromoanthanthrone; thioindigo pigments; porphyrazine compounds; zinc oxide; trigonal selenium; and bisazo pigments. etc. are preferred.

The charge-generating material described above may also be used when using an incoherent light source such as an LED or an organic EL image array that has an emission center wavelength of 450 nm or more and 780 nm or less, but from the viewpoint of resolution, the photosensitive layer should be 20 μm or less in thickness. When used in a thin film, the electric field strength in the photosensitive layer becomes high, and a decrease in charging due to charge injection from the substrate tends to cause image defects called so-called black spots. This becomes noticeable when charge generating materials such as trigonal selenium and phthalocyanine pigments, which are p-type semiconductors and tend to generate dark current, are used.

On the other hand, when n-type semiconductors such as condensed aromatic pigments, perylene pigments, and azo pigments are used as charge-generating materials, dark current is less likely to occur, and image defects called sunspots can be suppressed even in thin films. .
Note that the n-type is determined by the polarity of the flowing photocurrent using the commonly used time-of-flight method, and the n-type is determined if it is easier to flow electrons as carriers than holes.

The binder resin used in the charge generation layer is selected from a wide range of insulating resins, and the binder resin is selected from organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, polyvinylpyrene, and polysilane. You may choose.
Examples of the binder resin include polyvinyl butyral resin, polyarylate resin (polycondensate of bisphenols and aromatic divalent carboxylic acid, etc.), polycarbonate resin, polyester resin, phenoxy resin, vinyl chloride-vinyl acetate copolymer, Examples include polyamide resin, acrylic resin, polyacrylamide resin, polyvinylpyridine resin, cellulose resin, urethane resin, epoxy resin, casein, polyvinyl alcohol resin, polyvinylpyrrolidone resin, and the like. Here, "insulating" means that the volume resistivity is 10 ¹³ Ωcm or more.
These binder resins may be used alone or in combination of two or more.

Note that the blending ratio of the charge generating material and the binder resin is preferably within the range of 10:1 to 1:10 in terms of mass ratio.

The charge generation layer may also contain other well-known additives.

There are no particular restrictions on the formation of the charge generation layer, and well-known formation methods may be used. and heat as necessary. Note that the charge generation layer may be formed by vapor deposition of a charge generation material. Formation of the charge generation layer by vapor deposition is particularly suitable when a condensed aromatic pigment or perylene pigment is used as the charge generation material.

Examples of the solvent for preparing the coating solution for forming the charge generation layer include methanol, ethanol, n-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, and n-acetic acid. -butyl, dioxane, tetrahydrofuran, methylene chloride, chloroform, chlorobenzene, toluene and the like. These solvents may be used alone or in combination of two or more.

Examples of methods for dispersing particles (for example, charge generating material) in the coating liquid for forming a charge generating layer include media dispersing machines such as ball mills, vibrating ball mills, attritors, sand mills, and horizontal sand mills, stirring machines, and ultrasonic dispersing machines. Medialess dispersion machines such as , roll mills, and high-pressure homogenizers are used. Examples of the high-pressure homogenizer include a collision method in which the dispersion liquid is dispersed by liquid-liquid collision or liquid-wall collision under high pressure, and a penetration method in which the dispersion is dispersed by penetrating fine channels under high pressure.
In addition, during this dispersion, it is effective to keep the average particle size of the charge generating material in the coating liquid for forming a charge generating layer to 0.5 μm or less, preferably 0.3 μm or less, and more preferably 0.15 μm or less. .

Examples of methods for applying the charge generation layer forming coating liquid onto the subbing layer (or onto the intermediate layer) include blade coating, wire bar coating, spray coating, dip coating, bead coating, and air knife coating. For example, conventional methods such as a coating method and a curtain coating method may be used.

The thickness of the charge generation layer is, for example, preferably set within a range of 0.1 μm or more and 5.0 μm or less, more preferably 0.2 μm or more and 2.0 μm or less.

(charge transport layer)
The charge transport layer is, for example, a layer containing a charge transport material and a binder resin. The charge transport layer may be a layer containing a polymeric charge transport material.

As charge transport materials, quinone compounds such as p-benzoquinone, chloranil, bromanil, and anthraquinone; tetracyanoquinodimethane compounds; fluorenone compounds such as 2,4,7-trinitrofluorenone; xanthone compounds; benzophenone compounds Examples include electron transporting compounds such as cyanovinyl compounds; ethylene compounds. Examples of the charge transporting material include hole transporting compounds such as triarylamine compounds, benzidine compounds, arylalkane compounds, aryl-substituted ethylene compounds, stilbene compounds, anthracene compounds, and hydrazone compounds. These charge transport materials may be used alone or in combination of two or more, but are not limited thereto.

As the charge transport material, from the viewpoint of charge mobility, a triarylamine derivative represented by the following structural formula (a-1) and a benzidine derivative represented by the following structural formula (a-2) are preferable.

In structural formula (a-1), Ar ^T1 , Ar ^T2 , and Ar ^T3 each independently represent a substituted or unsubstituted aryl group, -C ₆ H ₄ -C(R ^T4 )=C(R ^T5 )(R ^T6 ), or -C ₆ H ₄ -CH=CH-CH=C(R ^T7 )(R ^T8 ). R ^T4 , R ^T5 , R ^T6 , R ^T7 , and R ^T8 each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group.
Examples of substituents for each of the above groups include a halogen atom, an alkyl group having 1 to 5 carbon atoms, and an alkoxy group having 1 to 5 carbon atoms. Furthermore, examples of the substituents for each of the above groups include a substituted amino group substituted with an alkyl group having 1 or more and 3 or less carbon atoms.

In structural formula (a-2), R ^T91 and R ^T92 each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms. ^RT101 , ^RT102 , ^RT111 and ^RT112 are each independently substituted with a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or an alkyl group having 1 to 2 carbon atoms represents an amino group, a substituted or unsubstituted aryl group, -C(R ^T12 )=C(R ^T13 )(R ^T14 ), or -CH=CH-CH=C(R ^T15 )(R ^T16 ), R ^T12 , R ^T13 , R ^T14 , R ^T15 and R ^T16 each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group. Tm1, Tm2, Tn1 and Tn2 each independently represent an integer of 0 or more and 2 or less.
Examples of substituents for each of the above groups include a halogen atom, an alkyl group having 1 to 5 carbon atoms, and an alkoxy group having 1 to 5 carbon atoms. Furthermore, examples of the substituents for each of the above groups include a substituted amino group substituted with an alkyl group having 1 or more and 3 or less carbon atoms.

Here, among the triarylamine derivative represented by the structural formula (a-1) and the benzidine derivative represented by the structural formula (a-2), in particular, "-C ₆ H ₄ -CH=CH-CH= Triarylamine derivatives having "C(R ^T7 )(R ^T8 )" and benzidine derivatives having "-CH=CH-CH=C(R ^T15 )(R ^T16 )" are preferred from the viewpoint of charge mobility.

As the polymeric charge transporting material, known materials having charge transporting properties such as poly-N-vinylcarbazole and polysilane are used. In particular, polyester-based polymeric charge transport materials are preferred. Note that the polymer charge transport material may be used alone, or may be used in combination with a binder resin.

The binder resin used for the charge transport layer includes polycarbonate resin, polyester resin, polyarylate resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinylidene chloride resin, polystyrene resin, polyvinyl acetate resin, styrene-butadiene copolymer, Vinylidene chloride-acrylonitrile copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicone resin, silicone alkyd resin, phenol-formaldehyde resin, styrene-alkyd resin, poly-N -Vinyl carbazole, polysilane, etc. Among these, polycarbonate resin or polyarylate resin is suitable as the binder resin. These binder resins may be used alone or in combination of two or more.
Note that the blending ratio of the charge transport material and the binder resin is preferably from 10:1 to 1:5 in terms of mass ratio.

Among the above binder resins, polycarbonate resins (such as bisphenol A, bisphenol Z, bisphenol C, bisphenol TP, etc. (polymerization type or copolymerization type thereof) is preferable. One type of polycarbonate resin may be used alone, or two or more types may be used in combination. Further, from the same point of view, it is more preferable that a homopolymerized polycarbonate resin of bisphenol Z is included among the polycarbonate resins.

In addition to the charge transport material and the binder resin, the charge transport layer may contain inorganic particles as necessary.
When the charge transport layer (ie, the outermost layer of the organic photosensitive layer) contains inorganic particles, cracking of the inorganic protective layer is suppressed. Specifically, by incorporating inorganic particles into the layer constituting the surface of the organic photosensitive layer, the inorganic particles function as a reinforcing material for the organic photosensitive layer, making it difficult for the organic photosensitive layer to deform. It is thought that cracking of the protective layer is suppressed. Furthermore, since the charge transport layer (that is, the organic photosensitive layer) contains inorganic particles, dielectric breakdown of the charge transport layer (that is, the organic photosensitive layer) is less likely to occur even if the electric field strength becomes high.

Inorganic particles used in the charge transport layer include silica particles, alumina particles, titanium oxide particles, potassium titanate, tin oxide particles, zinc oxide particles, zirconium oxide particles, barium sulfate particles, calcium oxide particles, calcium carbonate particles, and calcium oxide particles. Examples include magnesium particles.
One type of inorganic particles may be used alone, or two or more types may be used in combination.
Among these, silica particles are particularly preferred from the viewpoint of having a high dielectric loss factor, making it difficult to reduce the electrical characteristics of the photoreceptor, and suppressing the occurrence of cracks in the inorganic protective layer.
Silica particles suitable for the charge transport layer will be described in detail below.

Examples of the silica particles include dry silica particles and wet silica particles.
Examples of the dry silica particles include combustion method silica (fumed silica) obtained by burning a silane compound, deflagration method silica obtained by explosively burning metal silicon powder, and the like.
Wet silica particles include wet silica particles obtained by neutralizing sodium silicate and mineral acids (precipitated silica synthesized and aggregated under alkaline conditions, gel silica particles synthesized and aggregated under acidic conditions, etc.), and acidic silica particles. Examples include colloidal silica particles (silica sol particles, etc.) obtained by alkalinizing and polymerizing, and sol-gel silica particles obtained by hydrolyzing an organic silane compound (eg, alkoxysilane, etc.).
Among these, silica particles have few silanol groups on the surface and have a low void structure, from the viewpoint of suppressing image defects due to generation of residual potential and deterioration of electrical properties (suppression of deterioration of fine line reproducibility). Preferably, processed silica particles are used.

The surface of the silica particles is preferably treated with a hydrophobizing agent. This reduces the number of silanol groups on the surface of the silica particles, making it easier to suppress the generation of residual potential.
Examples of the hydrophobizing agent include well-known silane compounds such as chlorosilane, alkoxysilane, and silazane.
Among these, trimethylsilyl group, decylsilyl group, or phenylsilyl group is used as a hydrophobizing agent from the viewpoint of easily suppressing the generation of residual potential and suppressing image density unevenness caused by charging unevenness on the surface of the photoreceptor. A silane compound with That is, the surface of the silica particles preferably has a trimethylsilyl group, a decylsilyl group, or a phenylsilyl group.
Examples of the silane compound having a trimethylsilyl group (trimethylsilane compound) include trimethylchlorosilane, trimethylmethoxysilane, and 1,1,1,3,3,3-hexamethyldisilazane.
Examples of the silane compound having a decylsilyl group (decylsilane compound) include decyltrichlorosilane, decyldimethylchlorosilane, decyltrimethoxysilane, and the like.
Examples of the silane compound having a phenyl group (phenylsilane compound) include triphenylmethoxysilane and triphenylchlorosilane.

The condensation rate of hydrophobized silica particles (ratio of Si-O-Si in SiO ^{4 -} bonds in silica particles: hereinafter also referred to as "condensation rate of hydrophobizing agent") is determined by the surface of the silica particles, for example. The proportion is preferably 90% or more, preferably 91% or more, and more preferably 95% or more based on the silanol groups.
When the condensation rate of the hydrophobizing agent is within the above range, the number of silanol groups in the silica particles is further reduced, making it easier to suppress the generation of residual potential.

The condensation rate of the hydrophobizing agent indicates the ratio of condensed silicon to the total bondable sites of silicon in the condensation part detected by NMR (Nuclear Magnetic Resonance), and is measured as follows.
First, silica particles are separated from the layer. The separated silica particles were subjected to Si CP/MAS NMR analysis using Bruker's AVANCE III 400, and the peak area corresponding to the _number of SiO substitutions was determined _. -), 3-substitution (Si(OH)(0-Si) ₃ -), and 4-substitution (Si(0-Si) ₄ -) as Q2, Q3, and Q4, and the condensation rate of the hydrophobizing agent is expressed by the formula : Calculated by (Q2×2+Q3×3+Q4×4)/4×(Q2+Q3+Q4).

The volume resistivity of the silica particles is, for example, preferably 10 ¹¹ Ω·cm or more, preferably 10 ¹² Ω·cm or more, and more preferably 10 ¹³ Ω·cm or more.
When the volume resistivity of the silica particles is within the above range, deterioration of electrical properties is suppressed.

The volume resistivity of silica particles is measured as follows. Note that the measurement environment is a temperature of 20° C. and a humidity of 50% RH.
First, silica particles are separated from the layer. Then, separated silica particles to be measured are placed on the surface of a circular jig equipped with a 20 cm ² electrode plate to a thickness of about 1 mm or more and 3 mm or less to form a silica particle layer. A 20 cm ² electrode plate similar to the above was placed on top of this and the silica particle layer was sandwiched therebetween. In order to eliminate voids between silica particles, a load of 4 kg is applied to the electrode plate placed on the silica particle layer, and then the thickness (cm) of the silica particle layer is measured. Both electrodes above and below the silica particle layer are connected to an electrometer and a high-voltage power generator. A high voltage is applied to both electrodes so that the electric field becomes a predetermined value, and the volume resistivity (Ω·cm) of the silica particles is calculated by reading the current value (A) that flows at this time. The formula for calculating the volume resistivity (Ω·cm) of silica particles is as shown in the formula below.
In the formula, ρ is the volume resistivity (Ω cm) of the silica particles, E is the applied voltage (V), I is the current value (A), I0 is the current value (A) at the applied voltage of 0 V, and L is the silica particle. Each represents the thickness (cm) of the particle layer. In this evaluation, the volume resistivity when the applied voltage was 1000V was used.
・Formula: ρ=E×20/(I-I0)/L

The volume average particle size of the inorganic particles including silica particles is, for example, 20 nm or more and 200 nm or less, preferably 40 nm or more and 150 nm or less, more preferably 50 nm or more and 120 nm or less, and still more preferably 50 nm or more and 110 nm or less.
When the volume average particle size is within the above range, cracking of the inorganic protective layer and generation of residual potential can be easily suppressed.

The volume average particle diameter of inorganic particles is measured as follows. The measurement method for silica particles will be shown below, but the same measurement method can be used for other particles as well.
The volume average particle diameter of the silica particles can be determined by separating the silica particles from the layer, observing 100 primary particles of the silica particles at a magnification of 40,000 times using an SEM (Scanning Electron Microscope) device, and analyzing the image of the primary particles. Measure the longest diameter and shortest diameter of each ball, and measure the equivalent sphere diameter from this intermediate value. The 50% diameter (D50v) of the cumulative frequency of the obtained equivalent sphere diameter is determined, and this is measured as the volume average particle diameter of the silica particles.

The content of the inorganic particles may be appropriately determined depending on the type thereof, but from the viewpoint of easily suppressing cracking of the inorganic protective layer and generation of residual potential, the content of the inorganic particles relative to the entire charge transport layer (solid content) For example, the content is preferably 30% by mass or more, more preferably 40% by mass or more, even more preferably 50% by mass or more, and particularly preferably 55% by mass or more.
The upper limit of the content of inorganic particles is not particularly limited, but from the viewpoint of ensuring the characteristics of the charge transport layer, it is preferably 90% by mass or less, preferably 80% by mass or less, and 70% by mass or less. More preferably, it is 65% by mass or less.
Further, the content of the inorganic particles is preferably greater than the content of the charge transport material, and is preferably 55% by mass or more and 90% by mass or less based on the entire charge transport layer (solid content).

The charge transport layer may also contain other well-known additives.

-Characteristics of charge transport layer-
The surface roughness Ra (arithmetic mean surface roughness Ra) of the surface of the charge transport layer on the inorganic protective layer side is, for example, 0.06 μm or less, preferably 0.03 μm or less, more preferably 0.02 μm or less. be.
When the surface roughness Ra is within the above range, the smoothness of the inorganic protective layer increases and the cleaning performance improves.
In addition, in order to make the surface roughness Ra within the above range, for example, a method such as increasing the thickness of the layer can be mentioned.

This surface roughness Ra is measured as follows.
First, after peeling off the inorganic protective layer, the layer to be measured is exposed. Then, a part of the layer is cut out with a cutter or the like to obtain a measurement sample.
This measurement sample is measured using a stylus type surface roughness measuring device (Surfcom 1400A, manufactured by Tokyo Seimitsu Co., Ltd., etc.). The measurement conditions are based on JIS B0601-1994, with evaluation length Ln = 4 mm, reference length L = 0.8 mm, and cutoff value = 0.8 mm.

The elastic modulus of the charge transport layer is, for example, 5 GPa or more, preferably 6 GPa or more, and more preferably 6.5 GPa or more.
When the elastic modulus of the charge transport layer is within the above range, cracking of the inorganic protective layer can be easily suppressed.
Note that in order to set the elastic modulus of the charge transport layer within the above range, for example, a method of adjusting the particle size and content of silica particles, a method of adjusting the type and content of the charge transport material, and the like can be mentioned.

The elastic modulus of the charge transport layer is measured as follows.
First, after peeling off the inorganic protective layer, the layer to be measured is exposed. Then, a part of the layer is cut out with a cutter or the like to obtain a measurement sample.
For this measurement sample, a depth profile was obtained using the Continuous Stiffness Method (CSM) (US Pat. No. 4,848,141) using Nano Indenter SA2 manufactured by MTS Systems, and the depth profile was obtained from the measured values from the indentation depth of 30 nm to 100 nm. Measure using the average value.

The thickness of the charge transport layer is, for example, 10 μm or more and 40 μm or less, preferably 10 μm or more and 35 μm or less, and more preferably 15 μm or more and 30 μm or less.
When the thickness of the charge transport layer is within the above range, cracking of the inorganic protective layer and generation of residual potential can be easily suppressed.

-Formation of charge transport layer-
There are no particular restrictions on the formation of the charge transport layer, and well-known formation methods may be used. , by heating if necessary.

Examples of solvents for preparing the coating solution for forming the charge transport layer include aromatic hydrocarbons such as benzene, toluene, xylene, and chlorobenzene; ketones such as acetone and 2-butanone; and methylene chloride, chloroform, and ethylene chloride. Halogenated aliphatic hydrocarbons; common organic solvents such as cyclic or linear ethers such as tetrahydrofuran and ethyl ether; These solvents may be used alone or in combination of two or more.

Application methods for applying the charge transport layer forming coating liquid onto the charge generation layer include blade coating, wire bar coating, spray coating, dip coating, bead coating, air knife coating, and curtain coating. Usual methods such as coating methods can be used.

In addition, when dispersing particles (for example, silica particles or fluororesin particles) in the coating liquid for forming a charge transport layer, the dispersion method includes, for example, media dispersion using a ball mill, vibrating ball mill, attritor, sand mill, horizontal sand mill, etc. A media-less dispersion machine such as a machine, a stirrer, an ultrasonic dispersion machine, a roll mill, or a high-pressure homogenizer is used. Examples of high-pressure homogenizers include a collision method in which the dispersion liquid is dispersed by liquid-liquid collision or liquid-wall collision under high pressure, and a penetration method in which the dispersion is dispersed by penetrating fine channels under high pressure.

In addition, after the formation of the charge transport layer and before the formation of the inorganic protective layer, if necessary, the atmosphere contained in the organic photosensitive layer formed on the conductive substrate is replaced with a gas having a higher oxygen concentration than the atmosphere. You may also go through the process of

(Inorganic protective layer)
-Composition of inorganic protective layer-
The layer constituting the surface of the inorganic protective layer contains a metal element M, oxygen O, and hydrogen H. That is, the layer constituting the surface of the inorganic protective layer is made of an inorganic material containing the metal element M, oxygen O, and hydrogen H.
The elemental composition ratio of oxygen O and metal element M (oxygen O/metal element M) in the layer constituting the surface of the inorganic protective layer is 1.3 or more and 1.5 or less.
The inorganic protective layer is a monolayer of layers constituting the surface of the inorganic protective layer, in which the elemental composition ratio of oxygen O and metal element M (oxygen O/metal element M) is 1.3 or more and 1.5 or less. Alternatively, it may be composed of a laminate including a layer constituting the surface of the inorganic protective layer.
However, from the viewpoint of improving electrical properties, the surface of the inorganic protective layer has an elemental composition ratio of oxygen O and metal element M (oxygen O/metal element M) of 1.3 or more and 1.5 or less. It is preferable to be composed of a single layer of layers constituting.

In the layer constituting the surface of the inorganic protective layer, examples of the metal element M include Group 13 elements.
Group 13 elements include boron, aluminum, gallium, and indium.
Among these, from the viewpoint of electrical properties and wear resistance of the inorganic protective layer in the photoreceptor, the metal element M is preferably a group 13 element, and more preferably gallium.

The elemental composition ratio of oxygen O and metal element M (oxygen O/metal element M) in the layer constituting the surface of the inorganic protective layer is 1.3 or more and 1.5 or less, but the electrical properties of the photoreceptor From the viewpoint of the abrasion resistance of the inorganic protective layer, it is preferably 1.4 or more and 1.5 or less, and more preferably 1.46 or more and 1.5 or less.
On the other hand, the elemental composition ratio of oxygen O and metal element M (oxygen O/metal element M) in the layer constituting the surface of the inorganic protective layer is 1.3 or more and 1. .5 or less is more preferable.

In the layer constituting the surface of the inorganic protective layer, the sum of the elemental ratios of the metal element M, oxygen O, and hydrogen H to all the elements constituting the layer constituting the surface of the inorganic protective layer is the electrical property of the photoreceptor. From the viewpoint of the abrasion resistance of the inorganic protective layer, it is preferably 90% or more, more preferably 95%, and even more preferably 98%.

In addition to the above-mentioned inorganic materials, the layer constituting the surface of the inorganic protective layer contains one or more elements selected from C, Si, Ge, and Sn in the case of n-type conductivity, for example, in order to control the conductivity type. It's okay to stay. Further, for example, in the case of p-type, it may contain one or more elements selected from N, Be, Mg, Ca, and Sr.

Here, if the layer constituting the surface of the inorganic protective layer is configured to include the metal element M, oxygen O, and hydrogen H, from the viewpoint of excellent electrical properties and abrasion resistance of the inorganic protective layer in the photoreceptor. , suitable elemental composition ratios are as follows.
The elemental composition ratio of the metal element M is, for example, preferably 15 atom % or more and 50 atom % or less, preferably 20 atom % or more and 40 atom % or less, more preferably The content is 20 atomic % or more and 3 atomic % or less.
The elemental composition ratio of oxygen O is, for example, preferably 30 atomic % or more and 70 atomic % or less, preferably 40 atomic % or more and 60 atomic % or less, more preferably 45 atomic % or less, based on all the constituent elements of the inorganic protective layer. The content is at least 55 at %.
The elemental composition ratio of hydrogen H is, for example, preferably 10 atomic % or more and 40 atomic % or less, preferably 15 atomic % or more and 35 atomic % or less, and more preferably 20 atomic % or less, based on all the constituent elements of the inorganic protective layer. The content is at least 30 at %.

When the inorganic protective layer is composed of a laminate, from the viewpoint of improving the electrical properties of the photoreceptor, the elemental composition ratio of oxygen O and metal element M (oxygen O /metal element M) is preferably 1.2 or more and less than 1.3.
The layer below the layer constituting the surface of the inorganic protective layer has the same structure as the layer constituting the surface of the inorganic protective layer, except for the elemental composition ratio of oxygen O and metal element M (oxygen O/metal element M). That's good.

The element composition ratio, atomic number ratio, etc. of each element in the inorganic protective layer, including the distribution in the thickness direction, are determined by Rutherford back scattering (hereinafter referred to as "RBS"). Pelletron, CE&A RBS-400 as the end station, and 3S-R10 as the system are used. For analysis, CE&A's HYPRA program is used.
Note that the RBS measurement conditions are that the He++ ion beam energy is 2.275 eV, the detection angle is 160°, and the grazing angle is approximately 109° with respect to the incident beam.

Specifically, the RBS measurement is performed as follows: First, a He++ ion beam is incident perpendicularly to the sample, the detector is set at 160° with respect to the ion beam, and the backscattered He signal is Measure. The composition ratio and film thickness are determined from the detected energy and intensity of He. In order to improve the accuracy of determining the composition ratio and film thickness, the spectrum may be measured at two detection angles. Accuracy is improved by measuring and cross-checking at two detection angles with different depth resolutions and backscattering dynamics.
The number of He atoms backscattered by a target atom is determined by only three factors: 1) the atomic number of the target atom, 2) the energy of the He atom before scattering, and 3) the scattering angle. The density is assumed by calculation from the measured composition and is used to calculate the thickness. The density error is within 20%.

Note that the elemental composition ratio of hydrogen is determined by hydrogen forward scattering (hereinafter referred to as "HFS").
In the HFS measurement, NEC's 3SDH Pelletron is used as an accelerator, CE&A's RBS-400 is used as an end station, and 3S-R10 is used as a system. CE&A's HYPRA program is used for analysis. The HFS measurement conditions are as follows.
・He++ ion beam energy: 2.275eV
・Detection angle: Grazing angle 30° for 160° incident beam

In HFS measurement, the detector is set at 30° to the He++ ion beam and the sample is set at 75° from the normal to pick up hydrogen signals scattered in front of the sample. At this time, it is preferable to cover the detector with aluminum foil to remove He atoms scattered together with hydrogen. Quantification is performed by comparing the hydrogen counts of the reference sample and the sample to be measured after normalizing them by the stopping power. A sample obtained by implanting H ions into Si and muscovite are used as reference samples.
Muscovite is known to have a hydrogen concentration of 6.5 at.%.
The H adsorbed on the outermost surface is corrected, for example, by subtracting the amount of H adsorbed on the clean Si surface.

Note that the inorganic protective layer may have a composition ratio distributed in the thickness direction or may have a multilayer structure depending on the purpose.

-Characteristics of inorganic protective layer-
The light transmittance of the inorganic protective layer is preferably 90% or more, more preferably 95%.
When the light transmittance of the inorganic protective layer is within the above range, electrical properties are improved.
The light transmittance of the inorganic protective layer is measured as follows.
First, a sample is collected by forming an inorganic protective layer on quartz glass at the same time as forming a photoreceptor protective layer to be measured.
The light transmittance of a sample of an inorganic protective layer on quartz glass is measured using a spectrophotometer (UV-26000, manufactured by Shimadzu Corporation).

The volume resistivity of the inorganic protective layer is preferably 5.0×10 ⁹ Ωcm or more and less than 1.0×10 ¹³ Ωcm. The volume resistivity of the inorganic protective layer is more preferably 8.0×10 ¹⁰ Ωcm or more and 7.0× ¹² cm or less from the viewpoint of improving electrical properties.

This volume resistivity is calculated based on the electrode area and sample thickness from the resistance value measured under the conditions of a frequency of 100 Hz and a voltage of 1 V using an LCR meter ZM2371 manufactured by nF Corporation.
The measurement sample was a sample obtained by forming a film on an aluminum substrate under the same conditions as the inorganic protective layer to be measured, and forming a gold electrode on the film by vacuum evaporation. Alternatively, it may be a sample in which the inorganic protective layer is peeled off from the produced electrophotographic photoreceptor, a portion thereof is etched, and this is sandwiched between a pair of electrodes.

The inorganic protective layer is preferably a non-single crystal film such as a microcrystalline film, a polycrystalline film, or an amorphous film. Among these, an amorphous film is particularly desirable in terms of surface smoothness, but a microcrystalline film is more desirable in terms of hardness.
The growth cross section of the inorganic protective layer may have a columnar structure, but from the viewpoint of slipperiness, a highly flat structure is desirable, and an amorphous structure is desirable.
Note that crystallinity and amorphousness are determined by the presence or absence of points or lines in a diffraction image obtained by RHEED (reflection high-speed electron diffraction) measurement.

The elastic modulus of the inorganic protective layer is preferably 30 GPa or more and 80 GPa or less, preferably 40 GPa or more and 65 GPa or less.
When the elastic modulus is within the above range, occurrence of recesses (dent-like scratches), peeling, and cracking of the inorganic protective layer can be easily suppressed.
This elastic modulus is the average value obtained from the measured values from the indentation depth of 30 nm to 100 nm, obtained by obtaining a depth profile by the continuous stiffness method (CSM) (US Patent 4,848,141) using Nano Indenter SA2 manufactured by MTS Systems. Use. The following are the measurement conditions.
・Measurement environment: 23℃, 55%RH
・Indenter used: Diamond regular triangular pyramid indenter (Berkovic indenter) Triangular pyramid indenter ・Test mode: CSM mode The measurement sample was a sample formed on a substrate under the same conditions as the inorganic protective layer to be measured. Alternatively, it may be a sample obtained by peeling off the inorganic protective layer from the produced electrophotographic photoreceptor and partially etching it.

The thickness of the inorganic protective layer is, for example, preferably 0.2 μm or more and 10.0 μm or less, preferably 0.4 μm or more and 5.0 μm or less.
When the film thickness is within the above range, the electrical properties and abrasion resistance of the inorganic protective layer in the photoreceptor are improved.

- Formation of inorganic protective layer -
For forming the inorganic protective layer, a known vapor deposition method such as a plasma CVD (Chemical Vapor Deposition) method, an organometallic vapor phase epitaxy method, a molecular beam epitaxy method, vapor deposition, or sputtering is used.

Hereinafter, the formation of the inorganic protective layer will be explained by giving a specific example while showing an example of a film forming apparatus in the drawings. The following explanation describes a method for forming an inorganic protective layer containing gallium, oxygen, and hydrogen; however, the method is not limited to this, and well-known formation methods may be used depending on the composition of the intended inorganic protective layer. Just apply.

FIG. 3 is a schematic diagram showing an example of a film forming apparatus used for forming the inorganic protective layer of the electrophotographic photoreceptor according to the present embodiment, and FIG. 3(A) shows a side view of the film forming apparatus. 3(B) represents a schematic sectional view of the film forming apparatus shown in FIG. 3(A) between A1 and A2. In FIG. 3, 210 is a film forming chamber, 211 is an exhaust port, 212 is a substrate rotation unit, 213 is a substrate support member, 214 is a substrate, 215 is a gas introduction pipe, and 216 is a gas introduced from the gas introduction pipe 215. A shower nozzle having an opening, 217 a plasma diffusion section, 218 a high frequency power supply section, 219 a flat plate electrode, 220 a gas introduction tube, and 221 a high frequency discharge tube section.

In the film forming apparatus shown in FIG. 3, an exhaust port 211 connected to a vacuum evacuation device (not shown) is provided at one end of the film forming chamber 210, and the side of the film forming chamber 210 where the exhaust port 211 is provided. On the opposite side, a plasma generation device including a high frequency power supply section 218, a flat plate electrode 219, and a high frequency discharge tube section 221 is provided.
This plasma generating device includes a high-frequency discharge tube section 221, a flat plate electrode 219 disposed inside the high-frequency discharge tube section 221 and whose discharge surface is provided on the exhaust port 211 side, and a flat plate electrode 219 disposed outside the high-frequency discharge tube section 221. It is composed of a high frequency power supply section 218 connected to the discharge surface of the electrode 219 and the opposite surface. Note that a gas introduction tube 220 for supplying gas into the high frequency discharge tube section 221 is connected to the high frequency discharge tube section 221, and the other end of the gas introduction tube 220 is connected to a first tube (not shown). connected to a gas supply.

Note that the plasma generator shown in FIG. 4 may be used instead of the plasma generator provided in the film forming apparatus shown in FIG. 3. FIG. 4 is a schematic diagram showing another example of the plasma generating device used in the film forming apparatus shown in FIG. 3, and is a side view of the plasma generating device. In FIG. 4, 222 represents a high frequency coil, 223 represents a quartz tube, and 220 is the same as that shown in FIG. This plasma generator consists of a quartz tube 223 and a high-frequency coil 222 provided along the outer peripheral surface of the quartz tube 223. One end of the quartz tube 223 is connected to a film forming chamber 210 (not shown in FIG. 4). It is connected. Furthermore, a gas introduction tube 220 for introducing gas into the quartz tube 223 is connected to the other end of the quartz tube 223 .

In FIG. 4, a rod-shaped shower nozzle 216 extending along the discharge surface is connected to the discharge surface side of the flat plate electrode 219, and one end of the shower nozzle 216 is connected to a gas introduction pipe 215, and this gas The introduction pipe 215 is connected to a second gas supply source (not shown) provided outside the film forming chamber 210.
In addition, a substrate rotation unit 212 is provided in the film forming chamber 210, and a cylindrical substrate 214 is attached to a substrate support member such that the longitudinal direction of the shower nozzle 216 and the axial direction of the substrate 214 face each other. It is designed to be attached to the base body rotating part 212 via 213. During film formation, the base body 214 rotates in the circumferential direction as the base body rotating section 212 rotates. Note that as the base 214, for example, a photoreceptor or the like is used, in which an organic photosensitive layer is laminated in advance.

Formation of the inorganic protective layer is performed, for example, as follows.
First, oxygen gas (or helium (He) diluted oxygen gas), helium (He) gas, and hydrogen (H ₂ ) gas as necessary are introduced into the high-frequency discharge tube section 221 from the gas introduction tube 220, and Radio waves of 13.56 MHz are supplied from the high frequency power supply section 218 to the flat plate electrode 219. At this time, the plasma diffusion portion 217 is formed to spread radially from the discharge surface side of the flat plate electrode 219 toward the exhaust port 211 side. Here, the gas introduced from the gas introduction pipe 220 flows through the film forming chamber 210 from the flat electrode 219 side to the exhaust port 211 side. The flat plate electrode 219 may be surrounded by an earth shield.

Next, trimethyl gallium gas is introduced into the film forming chamber 210 through the gas introduction pipe 215 and the shower nozzle 216 located downstream of the flat plate electrode 219 which is an activation device, thereby producing gallium and oxygen on the surface of the substrate 214. A non-single crystal film containing hydrogen is formed.
As the base 214, for example, a base on which an organic photosensitive layer is formed is used.

Since an organic photoreceptor having an organic photosensitive layer is used, the temperature of the surface of the substrate 214 during the formation of the inorganic protective layer is preferably 150° C. or lower, more preferably 100° C. or lower, and particularly preferably 30° C. or higher and 100° C. or lower.
Even if the temperature of the surface of the substrate 214 is 150° C. or lower at the beginning of film formation, if it becomes higher than 150° C. due to the influence of plasma, the organic photosensitive layer may be damaged by heat, so this effect should be taken into consideration. It is desirable to control the surface temperature of the base 214 by using the following steps.
The temperature of the surface of the base 214 may be controlled by at least one of a heating device and a cooling device (not shown in the figure), or may be left to the natural temperature rise during discharge. When heating the base 214, a heater may be installed outside or inside the base 214. When cooling the base 214, a cooling gas or liquid may be circulated inside the base 214.
If it is desired to avoid an increase in the temperature of the surface of the base 214 due to discharge, it is effective to adjust the high-energy gas flow that hits the surface of the base 214. In this case, conditions such as gas flow rate, discharge output, and pressure are adjusted to achieve the required temperature.

Further, instead of trimethylgallium gas, an organometallic compound containing aluminum or a hydride such as diborane may be used, and two or more types of these may be mixed.
For example, in the initial stage of forming the inorganic protective layer, a film containing nitrogen and indium is formed on the substrate 214 by introducing trimethylindium into the film forming chamber 210 through the gas introduction pipe 215 and the shower nozzle 216. This film then absorbs ultraviolet rays that are generated during continuous film formation and degrade the organic photosensitive layer. Therefore, damage to the organic photosensitive layer due to the generation of ultraviolet rays during film formation is suppressed.

In addition, doping methods for dopants during film formation include SiH ₃ and SnH ₄ for n-type use, and biscyclopentadienylmagnesium, dimethylcalcium, dimethylstrontium, etc. in gaseous form for p-type use. use. Further, in order to dope the dopant element into the surface layer, a known method such as a thermal diffusion method or an ion implantation method may be employed.
Specifically, for example, by introducing a gas containing at least one dopant element into the film forming chamber 210 through the gas introduction pipe 215 and the shower nozzle 216, conductivity types such as n-type and p-type are introduced. Obtain an inorganic protective layer.

In the film forming apparatus described using FIGS. 3 and 4, active nitrogen or active hydrogen formed by discharge energy may be independently controlled by providing a plurality of activation devices, or may be formed by controlling nitrogen atoms such as NH ₃ independently. A gas containing hydrogen atoms at the same time may be used. Furthermore, _H2 may be added. Further, conditions may be used in which active hydrogen is generated freely from the organometallic compound.
By doing so, activated carbon atoms, gallium atoms, nitrogen atoms, hydrogen atoms, and the like exist in a controlled state on the surface of the base 214. The activated hydrogen atoms have the effect of desorbing hydrogen from hydrocarbon groups such as methyl groups and ethyl groups constituting the organometallic compound as molecules.
Therefore, a hard film (inorganic protective layer) that constitutes a three-dimensional bond is formed.

Although the plasma generation device of the film forming apparatus shown in FIGS. 3 and 4 uses a high frequency oscillation device, it is not limited to this. For example, a microwave oscillation device may be used, or an electromagnetic A cyclotron resonance type or helicon plasma type device may also be used. Furthermore, in the case of a high frequency oscillation device, it may be of an inductive type or a capacitive type.
Furthermore, two or more of these devices may be used in combination, or two or more of the same type of devices may be used. Although a high frequency oscillator is desirable for suppressing the temperature rise on the surface of the base 214 due to plasma irradiation, a device for suppressing heat irradiation may be provided.

When using two or more different types of plasma generators (plasma generators), it is desirable that discharge be generated at the same time under the same pressure. Further, a pressure difference may be provided between the region where the discharge occurs and the region where the film is formed (the part where the base body is installed). These devices may be arranged in series with the gas flow that is formed from the part where the gas is introduced to the part where it is discharged in the film forming apparatus, or both devices may be arranged in series with the gas flow that is formed from the part where the gas is introduced to the part where the gas is discharged. They may be arranged to face each other.

For example, when two types of plasma generators are installed in series with respect to the gas flow, taking the film forming apparatus shown in FIG. It is used as a second plasma generator. In this case, for example, a high frequency voltage is applied to the shower nozzle 216 via the gas introduction pipe 215 to cause discharge in the film forming chamber 210 using the shower nozzle 216 as an electrode. Alternatively, instead of using the shower nozzle 216 as an electrode, a cylindrical electrode is provided between the base 214 and the flat electrode 219 in the film forming chamber 210, and this cylindrical electrode is used to cause a discharge inside.
Furthermore, when using two different types of plasma generators under the same pressure, for example, when using a microwave oscillator and a high-frequency oscillator, the excitation energy of the excited species can be greatly changed, which can be used to control film quality. It is valid. Further, the discharge may be performed at near atmospheric pressure (70,000 Pa or more and 110,000 Pa or less). When performing discharge near atmospheric pressure, it is desirable to use He as a carrier gas.

To form the inorganic protective layer, for example, a substrate 214 on which an organic photosensitive layer is formed is installed in the film forming chamber 210, and mixed gases having different compositions are introduced to form the inorganic protective layer.

Further, as the film forming conditions, for example, when discharging by high frequency discharge, in order to form a high quality film at low temperature, it is desirable that the frequency is in the range of 10 kHz or more and 50 MHz or less. Further, although the output depends on the size of the base 214, it is preferably in the range of 0.01 W/cm ² or more and 0.2 W/cm ^{2 or} less relative to the surface area of the base. The rotational speed of the base 214 is preferably in the range of 0.1 rpm or more and 500 rpm or less.

(Single layer type photosensitive layer)
The single-layer type photosensitive layer (charge generation/charge transport layer) is a layer containing, for example, a charge generation material, a charge transport material, and, if necessary, a binder resin and other well-known additives. Note that these materials are the same as those described for the charge generation layer and the charge transport layer.
The content of the charge generating material in the single-layer photosensitive layer is preferably 0.1% by mass or more and 10% by mass or less, preferably 0.8% by mass or more and 5% by mass or less based on the total solid content. . Further, the content of the charge transporting material in the single-layer type photosensitive layer is preferably 5% by mass or more and 50% by mass or less based on the total solid content.
The method for forming the single-layer type photosensitive layer is the same as the method for forming the charge generation layer and the charge transport layer.
The thickness of the single-layer type photosensitive layer is, for example, preferably 5 μm or more and 50 μm or less, preferably 10 μm or more and 40 μm or less.

[Charging device]
The charging device 15 charges the surface of the photoreceptor 12 .
The charging device 15 includes, for example, a contact-type charging member 14 that is provided in contact with the surface of the photoreceptor 12 and charges the surface of the photoreceptor 12, and an AC power supply 28 (for charging member) that applies an AC voltage to the charging member 14. (an example of an AC voltage applying section). AC power source 28 is electrically connected to charging member 14 .

Examples of the contact-type charging member 14 include contact-type chargers using a conductive charging roll, a charging brush, a charging film, a charging rubber blade, a charging tube, and the like.

The peak-to-peak voltage _Vpp of the AC voltage applied to the charging member 14 by the AC power supply 28 is 350 V or less and 4000 V or less (preferably 800 V or less and 1500 V or less), and the frequency is 100 Hz or more (preferably 2500 V or more). good.
Here, the AC power supply 28 may apply to the charging member 14 a superimposed voltage in which an AC voltage is superimposed on a DC voltage.

The charging device 15 is not limited to a form that includes a contact-type charging member 14 and an AC power source 28 that applies a charging voltage to the charging member 14, and as shown in FIG. , a non-contact charging member 14A that is provided upstream of the contact charging member 14 in the rotational direction of the photoreceptor 12 and charges the surface of the photoreceptor 12, and a DC voltage is applied to the non-contact charging member 14A. It may also be an embodiment including a DC power supply 28A (an example of a DC voltage applying section).
Examples of the non-contact type charging member 14A include a known charger such as a non-contact type roller charger, a scorotron charger using corona discharge, or a corotron charger.

In the case of this embodiment, the peak-to-peak voltage _Vpp of the AC voltage applied to the contact-type charging member 14 by the AC power source 28 is preferably 1000 V or less and 4000 V or less, and the frequency is preferably 2500 Hz or more.
On the other hand, the DC voltage applied to the non-contact charging member 14A by the DC power supply 28A is preferably 600V or less and 1000V or less.

In this embodiment, the contact charging member 14 functions as an auxiliary charging member and plays the role of injecting electrons into the photoreceptor 12. Therefore, even if the non-contact charging member 14A is used, the electrical characteristics of the photoreceptor 12 and the wear resistance of the inorganic protective layer is improved.

[Electrostatic image forming device]
The electrostatic image forming device 16 forms an electrostatic image on the surface of the charged photoreceptor 12 . Specifically, for example, the electrostatic image forming device 16 irradiates the surface of the photoreceptor 12 charged by the charging member 14 with light L modulated based on the image information of the image to be formed. , an electrostatic charge image corresponding to the image of the image information is formed on the photoreceptor 12.

Examples of the electrostatic image forming device 16 include optical equipment having a light source that imagewise exposes light such as semiconductor laser light, LED light, and liquid crystal shutter light.

[Developing device]
The developing device 18 is provided, for example, on the downstream side in the rotational direction of the photoreceptor 12 from the irradiation position of the light L by the electrostatic image forming device 16. The developing device 18 is provided with a storage section that stores developer. This storage section stores an electrostatic image developer containing toner. For example, the toner is stored in the developing device 18 in a charged state.

Further, in the image forming apparatus shown in FIG. 1, fatty acid metal salt particles are added to the developer (the toner) contained in the developing device 18. It also serves as a supply device that supplies fatty acid metal salt to the contact portion with the cleaning blade 22A.
The details of the fatty acid metal salt particles added to the developer (its toner) will be described later.

The developing device 18 includes, for example, a developing member 18A that develops an electrostatic image formed on the surface of the photoreceptor 12 with a developer containing toner, and a power source 32 that applies a developing voltage to the developing member 18A. There is. This developing member 18A is electrically connected to a power source 32, for example.

The developing member 18A of the developing device 18 is selected depending on the type of developer, and includes, for example, a developing roll having a developing sleeve with a built-in magnet.

The developing device 18 (including a power source 32) is electrically connected to, for example, a control device 36 provided in the image forming apparatus 10, and is driven and controlled by the control device 36 to apply a developing voltage to the developing member 18A. do. The developing member 18A to which the developing voltage is applied is charged to a developing potential corresponding to the developing voltage. The developing member 18A charged to a developing potential, for example, holds the developer contained in the developing device 18 on its surface and transfers the toner contained in the developer from inside the developing device 18 to the surface of the photoreceptor 12. supply The formed electrostatic charge image is developed as a toner image on the surface of the photoreceptor 12 to which the toner is supplied.

[Transfer device]
The transfer device 31 is provided, for example, on the downstream side in the rotational direction of the photoreceptor 12 from the location where the developing member 18A is provided. The transfer device 31 includes, for example, a transfer member 20 that transfers the toner image formed on the surface of the photoreceptor 12 to the recording medium 30A, and a power source 30 that applies a transfer voltage to the transfer member 20. The transfer member 20 has a cylindrical shape, for example, and conveys the recording medium 30A while sandwiching the recording medium 30A between the transfer member 20 and the photoreceptor 12. The transfer member 20 is electrically connected to a power source 30, for example.

As the transfer member 20, for example, a contact type transfer charger using a belt, a roller, a film, a rubber cleaning blade, etc., a scorotron transfer charger using corona discharge, a corotron transfer charger, etc., which are known per se, are non-contact type. Examples include transfer chargers.

The transfer device 31 (including the power supply 30) is electrically connected to, for example, a control device 36 provided in the image forming apparatus 10, and is driven and controlled by the control device 36 to apply a transfer voltage to the transfer member 20. do. The transfer member 20 to which the transfer voltage is applied is charged to a transfer potential corresponding to the transfer voltage.

When a transfer voltage having a polarity opposite to that of the toner constituting the toner image formed on the photoreceptor 12 is applied to the transfer member 20 from the power supply 30 of the transfer member 20, for example, the relationship between the photoreceptor 12 and the transfer member 20 is In the opposing region (see transfer region 32A in FIG. 1), a transfer electric field is formed with an electric field strength that moves each toner constituting the toner image on the photoreceptor 12 from the photoreceptor 12 to the transfer member 20 side by electrostatic force. be done.

The recording medium 30A is, for example, accommodated in a storage unit (not shown), and is transported from the storage unit along the transport path 34 by a plurality of transport members (not shown), and is transported between the photoreceptor 12 and the transfer member 20. The transfer region 32A, which is an opposing region, is reached. In the example shown in FIG. 1, the paper is transported in the direction of arrow B. When the recording medium 30A reaches the transfer area 32A, the toner image on the photoreceptor 12 is transferred by a transfer electric field formed in the area by applying a transfer voltage to the transfer member 20, for example. That is, for example, by moving the toner from the surface of the photoreceptor 12 to the recording medium 30A, a toner image is transferred onto the recording medium 30A. Then, the toner image on the photoreceptor 12 is transferred onto the recording medium 30A by the transfer electric field.

[Cleaning device]
The cleaning device 22 is provided downstream of the transfer area 32A in the rotational direction of the photoreceptor 12. The cleaning device 22 cleans residual toner adhering to the photoreceptor 12 after transferring the toner image onto the recording medium 30A. The cleaning device 22 cleans not only residual toner but also deposits such as paper dust.

The cleaning device 22 has a cleaning blade 22A, and removes deposits on the surface of the photoreceptor 12 by bringing the tip of the cleaning blade 22A into contact with the photoreceptor 12 in a direction opposite to the rotational direction of the photoreceptor 12.

[Static eliminator]
The static eliminator 24 is provided, for example, on the downstream side of the cleaning device 22 in the rotational direction of the photoreceptor 12 . After transferring the toner image, the static eliminator 24 exposes the surface of the photoreceptor 12 to remove static electricity. Specifically, for example, the static eliminator 24 is electrically connected to a control device 36 provided in the image forming apparatus 10, and is driven and controlled by the control device 36 to cover the entire surface of the photoreceptor 12 (specifically, For example, the entire surface of the image forming area) is exposed to light to eliminate static electricity.

Examples of the static eliminator 24 include devices having a light source such as a tungsten lamp that emits white light and a light emitting diode (LED) that emits red light.

[Fusing device]
The fixing device 26 is provided, for example, on the downstream side in the conveyance direction of the conveyance path 34 of the recording medium 30A from the transfer area 32A. The fixing device 26 includes a fixing member 26A and a pressure member 26B disposed in contact with the fixing member 26A, and the image is transferred onto the recording medium 30A at the contact portion between the fixing member 26A and the pressure member 26B. fixes the toner image. Specifically, for example, the fixing device 26 is electrically connected to a control device 36 provided in the image forming apparatus 10, and is driven and controlled by the control device 36 to fix the toner transferred onto the recording medium 30A. The image is fixed on the recording medium 30A by heat and pressure.

The fixing device 26 includes a known fixing device such as a heat roller fixing device, an oven fixing device, and the like.
Specifically, for example, the fixing device 26 may be a known fixing device including a fixing roll or a fixing belt as the fixing member 26A, and a pressure roll or a pressure belt as the pressure member 26B.

Here, the recording medium 30A, onto which the toner image is transferred by being conveyed along the conveyance path 34 and passing through an area (transfer area 32A) where the photoreceptor 12 and the transfer member 20 face each other, is not shown in the drawings, for example. The conveyance member further moves along the conveyance path 34 to the installation position of the fixing device 26, where the toner image on the recording medium 30A is fixed.

The recording medium 30A on which an image is formed by fixing the toner image is discharged to the outside of the image forming apparatus 10 by a plurality of transport members (not shown). Note that after the photoreceptor 12 is neutralized by the static eliminator 24, it is charged again to the charging potential by the charging device 15.

[Operation of image forming apparatus]
An example of the operation of the image forming apparatus 10 according to this embodiment will be described. Note that various operations of the image forming apparatus 10 are performed by a control program executed by the control device 36.

The image forming operation of the image forming apparatus 10 will be explained.
First, the surface of the photoreceptor 12 is charged by the charging device 15 . The electrostatic image forming device 16 exposes the charged surface of the photoreceptor 12 to light based on image information. As a result, an electrostatic charge image is formed on the photoreceptor 12 in accordance with the image information. In the developing device 18, the electrostatic image formed on the surface of the photoreceptor 12 is developed using a developer containing toner. As a result, a toner image is formed on the surface of the photoreceptor 12. Furthermore, fatty acid metal salt particles are added to the developer (the toner thereof) stored in the developing device 18, and the fatty acid metal salt particles are also supplied to the surface of the photoreceptor 12 together with the toner.
In the transfer device 31, the toner image formed on the surface of the photoreceptor 12 is transferred onto the recording medium 30A. The toner image transferred to the recording medium 30A is fixed by the fixing device 26.
On the other hand, the surface of the photoconductor 12 after the toner image has been transferred is cleaned by the cleaning blade 22A of the cleaning device 22, and then the static electricity is removed by the static eliminator 24. Note that some of the particles of the fatty acid metal salt supplied to the surface of the photoreceptor 12 in the developing device 18 remain on the surface of the photoreceptor 12 even after the toner image is transferred by the transfer device 31, and the particles of the fatty acid metal salt supplied to the surface of the photoreceptor 12 in the developing device 18 remain on the surface of the photoreceptor 12 even after the toner image is transferred by the transfer device 31. supplied to the contact position.
Therefore, the presence of the fatty acid metal salt at the contact position between the cleaning blade 22A and the photoreceptor 12 allows the cleaning blade 22A to exhibit high cleaning performance.

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples at all.

<Preparation of electrophotographic photoreceptor>
[Preparation of silica particles]
A trimethylsilane compound (1,1,1,3,3 , 3-hexamethyldisilazane (manufactured by Tokyo Kasei Co., Ltd.) was added thereto, and the mixture was allowed to react for 24 hours, and then filtered to obtain hydrophobized silica particles. This was designated as silica particles (1). The condensation rate of this silica particle (1) was 93%.

[Production of electrophotographic photoreceptor 1]
-Preparation of subbing layer-
Zinc oxide: 100 parts by mass (average particle diameter 70 nm, manufactured by Teika Co., Ltd., specific surface area value 15 m ² /g) was stirred and mixed with 500 parts by mass of tetrahydrofuran, and silane coupling agent (KBM503: manufactured by Shin-Etsu Chemical Co., Ltd.) 1.3 parts by mass were added and stirred for 2 hours. Thereafter, tetrahydrofuran was distilled off under reduced pressure, and baking was performed at 120° C. for 3 hours to obtain zinc oxide surface-treated with a silane coupling agent.

110 parts by mass of the surface-treated zinc oxide (silane coupling agent surface-treated zinc oxide) was stirred and mixed with 500 parts by mass of tetrahydrofuran, and a solution of 0.6 parts by mass of alizarin dissolved in 50 parts by mass of tetrahydrofuran was prepared. and stirred at 50°C for 5 hours. Thereafter, the alizarin-added zinc oxide was filtered out by vacuum filtration, and further vacuum drying was performed at 60°C to obtain alizarin-added zinc oxide.

60 parts by mass of this alizarin-added zinc oxide, 13.5 parts by mass of a curing agent (blocked isocyanate Sumidur 3175, manufactured by Sumitomo Bayern Urethane), and 15 parts by mass of butyral resin (S-LEC BM-1, manufactured by Sekisui Chemical Co., Ltd.) and 85 parts by mass of methyl ethyl ketone were mixed to obtain a liquid mixture. 38 parts by mass of this mixed solution and 25 parts by mass of methyl ethyl ketone were mixed and dispersed for 2 hours in a sand mill using glass beads of 1 mm diameter to obtain a dispersion liquid.

To the obtained dispersion, 0.005 parts by mass of dioctyltin dilaurate and 40 parts by mass of silicone resin particles (Tospearl 145, manufactured by Momentive Performance Materials) were added as a catalyst to form an undercoat layer. A coating solution was obtained. This coating solution was applied by dip coating onto an aluminum substrate with a diameter of 60 mm, a length of 357 mm, and a wall thickness of 1 mm, and dried and cured at 170° C. for 40 minutes to obtain a subbing layer with a thickness of 19 μm.

-Preparation of charge generation layer-
Positions where the Bragg angle (2θ±0.2°) of an X-ray diffraction spectrum using Cukα characteristic X-rays as a charge generating substance is at least 7.3°, 16.0°, 24.9°, or 28.0° Consisting of 15 parts by mass of hydroxygallium phthalocyanine having a diffraction peak at The mixture was dispersed in a sand mill for 4 hours using glass beads having a diameter of 1 mm. 175 parts by weight of n-butyl acetate and 180 parts by weight of methyl ethyl ketone were added to the obtained dispersion and stirred to obtain a coating liquid for forming a charge generation layer. This coating solution for forming a charge generation layer was applied onto the undercoat layer by dip coating and dried at room temperature (25° C.) to form a charge generation layer having a thickness of 0.2 μm.

-Preparation of charge transport layer-
250 parts by mass of tetrahydrofuran was added to 50 parts by mass of silica particles (1), and while keeping the liquid temperature at 20°C, 4-(2,2-diphenylethyl)-4',4''-dimethyl-trifluoride was added as a charge transport material. 25 parts by mass of phenylamine and 25 parts by mass of bisphenol Z type polycarbonate resin (viscosity average molecular weight: 30,000) as a binder resin were added and mixed with stirring for 12 hours to obtain a coating liquid for forming a charge transport layer.

This coating liquid for forming a charge transport layer was applied onto the charge generation layer and dried at 135° C. for 40 minutes to form a charge transport layer having a thickness of 30 μm, thereby obtaining an organic photoreceptor (1).

Through the above steps, an organic photoreceptor (1) was obtained in which an undercoat layer, a charge generation layer, and a charge transport layer were laminated in this order on an aluminum substrate.

- Formation of inorganic protective layer -
Next, an inorganic protective layer made of gallium oxide containing hydrogen was formed on the surface of the organic photoreceptor (1). This inorganic protective layer was formed using a film forming apparatus having the configuration shown in FIG.

First, the organic photoreceptor (1) was placed on the substrate support member 213 in the film forming chamber 210 of the film forming apparatus, and the inside of the film forming chamber 210 was evacuated through the exhaust port 211 until the pressure reached 0.1 Pa.
Next, 40% oxygen gas diluted with He (flow rate 5.7 sccm) and hydrogen gas (flow rate 500 sccm) are introduced from the gas introduction tube 220 into the high frequency discharge tube section 221 in which the flat plate electrode 219 with a diameter of 85 mm is provided. A radio frequency of 13.56 MHz was set to an output of 500 W using the high frequency power supply unit 218 and a matching circuit (not shown in FIG. 3), and matching was performed using a tuner to cause discharge from the flat plate electrode 219. The reflected wave at this time was 0W.
Next, trimethyl gallium gas (flow rate: 1.9 sccm) was introduced into the plasma diffusion section 217 in the film forming chamber 210 from the shower nozzle 216 via the gas introduction pipe 215. At this time, the reaction pressure inside the film forming chamber 210 measured with a Baratron vacuum gauge was 5.3 Pa.
In this state, a film was formed for 68 minutes while rotating the organic photoreceptor (1) at a speed of 500 rpm to form an inorganic protective layer with a thickness of 6 μm on the surface of the charge transport layer of the organic photoreceptor (1).
The surface roughness Ra of the outer peripheral surface of the inorganic protective layer was 1.9 nm.

The elemental composition ratio of oxygen and gallium (O/M=oxygen/gallium) in the inorganic protective layer was 1.45.

Through the above steps, an electrophotographic photoreceptor 1 was obtained in which an undercoat layer, a charge generation layer, a charge transport layer, and an inorganic protective layer were sequentially formed on a conductive substrate.

[Production of electrophotographic photoreceptor 2]
Electrophotographic photoreceptor 2 was obtained in the same manner as electrophotographic photoreceptor 1 except that the flow rate of 40% oxygen gas diluted with He was changed to 4.8 sccm in forming the inorganic protective layer.

[Production of electrophotographic photoreceptor 3]
Electrophotographic photoreceptor 3 was obtained in the same manner as electrophotographic photoreceptor 1 except that the flow rate of 40% oxygen gas diluted with He was changed to 5.3 sccm in forming the inorganic protective layer.

[Production of electrophotographic photoreceptor 4]
Electrophotographic photoreceptor 4 was obtained in the same manner as electrophotographic photoreceptor 1 except that the flow rate of 40% oxygen gas diluted with He was changed to 8.6 sccm in forming the inorganic protective layer.

[Production of electrophotographic photoreceptors 5 to 8]
Electrophotographic photoreceptors 5 to 8 were obtained in the same manner as electrophotographic photoreceptor 1 except that the film forming time was adjusted to have the film thickness shown in Table 1 in forming the inorganic protective layer.

[Production of electrophotographic photoreceptor 9]
Electrophotographic photoreceptor 9 was obtained in the same manner as electrophotographic photoreceptor 1 except that trimethylaluminum was used instead of trimethylgallium as the source gas in forming the inorganic protective layer.

[Production of electrophotographic photoreceptor 10]
Electrophotographic photoreceptor 10 was obtained in the same manner as electrophotographic photoreceptor 1 except that dimethylzinc was used instead of trimethylgallium as the source gas in forming the inorganic protective layer.

[Production of electrophotographic photoreceptor 11]
In forming the inorganic protective layer, the electrophotographic method was used except that the flow rate ratio of trimethyl gallium gas and He diluted 40% oxygen gas was changed midway through so that the film thickness and composition of the surface layer and the lower layer were as shown in Table 1. An electrophotographic photoreceptor 11 was obtained in the same manner as photoreceptor 1.

[Production of electrophotographic photoreceptor C1]
Electrophotographic photoreceptor C1 was obtained in the same manner as electrophotographic photoreceptor 1 except that the flow rate of the 40% oxygen gas diluted with He was changed to 1.5 sccm in forming the inorganic protective layer.

[Production of electrophotographic photoreceptor C2]
Electrophotographic photoreceptor C2 was obtained in the same manner as electrophotographic photoreceptor 1 except that the flow rate of 40% oxygen gas diluted with He was changed to 12.5 sccm in forming the inorganic protective layer.

<Examples 1 to 20, Comparative Examples 1 to 3>
The image forming apparatus (1) is a modified image forming apparatus "VERSANT 180Press (manufactured by Fujifilm Business Innovation Co., Ltd.)" (as shown in Figure 1, a contact-type charging roll and an AC power supply that applies an AC voltage to the charging roll) are used. An image forming apparatus (equipped with an image forming apparatus) was prepared.
The photoreceptor of each example was mounted on the prepared image forming apparatus.
Then, the peak-to-peak voltage Vpp and frequency of the AC voltage applied to the charging roll by the AC power source were as shown in Table 1, and the following evaluation was performed.
However, in Comparative Example 3, an image forming apparatus equipped with a contact-type charging roll and a DC power supply that applies DC voltage to the charging roll was prepared as a modified image forming apparatus "VERSANT180Press (manufactured by Fujifilm Business Innovation Co., Ltd.)". did.

The abbreviations in Table 1 are as follows.
・O/M: Elemental composition ratio of oxygen O and the metal element M (oxygen O/metal element M)
-IR CH/MO: Indicates the ratio ((C+H)/(M+O)) of C element + H element and M element + O element in the inorganic protective layer. The evaluation method is IR measurement, which is defined by the intensity ratio of infrared spectral absorption. Specifically, it is as follows.
CH is the intensity of infrared spectral absorption near 3000 cm ⁻¹ caused by C element + H element, and MO is the intensity of infrared spectral absorption near 500 cm ⁻¹ caused by M element + O element.
For infrared absorption spectrum measurement, we used PerkinElmer's Soectrum One Fourier Transform Infrared Absorption Measurement System B with an S/N ratio of 30,000:1 and a resolution of 4 cm (-1) ↑ to measure the sample deposited on a crystalline Si substrate. The sample was placed on a sample stand equipped with a beam condenser and then measured. A silicon wafer with no film deposited was used as a reference.

(Electrical characteristics of photoreceptor)
The actual internal potential and density gradation of VERSANT180Press were evaluated. Then, evaluation was made according to the following criteria.
A: Photoreceptor surface potential after exposure -250V or less B: Photoreceptor surface potential after exposure higher than -250V, -300V or less C: Photoreceptor surface potential after exposure, higher than -300V, -350V or less D: Electrical property problem. Deterioration of concentration output

(Abrasion resistance of photoreceptor)
Judgment was made based on the wear rate using VERSANT180Press. Specifically, the amount of wear (unit: nm) per 1000 revolutions (denoted as kcycle) of the photoreceptor was evaluated using the following criteria.
A: 0.08 nm/kcycle or less B: Greater than 0.08 nm/kcycle, 0.1 nm/kcycle or less C: Greater than 0.1 nm/kcycle, 0.13 nm/kcycle or less D: Occurrence of crack defects due to wear

<Examples 101 to 111>
The image forming apparatus is a modified image forming apparatus "VERSANT 180Press (manufactured by Fujifilm Business Innovation Co., Ltd.)" (as shown in Figure 2, it uses a contact charging roll, an AC power supply that applies an AC voltage to the charging roll, and a non-contact charging roll). The electrical properties and abrasion resistance of the photoconductor were examined in the same manner as in Example 1, except that an image forming apparatus (equipped with a scorotron charger and a DC power source for applying a DC voltage to the scorotron charger) was prepared. evaluated.
However, the peak-to-peak voltage Vpp and frequency of the AC voltage applied to the charging roll by the AC power supply, and the DC voltage applied to the Scorotron charger by the DC power supply were as shown in Table 2, and the same evaluation as in Example 1 was conducted. .

From the above results, it can be seen that the present example is superior in electrical properties and abrasion resistance of the inorganic protective layer in the electrophotographic photoreceptor compared to the comparative example.

10 Image forming device 12 Photoreceptor 14 Contact type charging member 15 Charging device 16 Electrostatic image forming device 18 Developing device 20 Transfer member 22 Cleaning device 22A Cleaning blade 24 Static eliminator 26 Fixing device 30A Recording medium 31 Transfer device 36 Control device 64 External supply device 66A Fatty acid metal salt 101 Subbing layer 102 Charge generation layer 103 Charge transport layer 104 Conductive substrate 105 Photosensitive layer 106 Inorganic protective layer 107A, 107B Electrophotographic photoreceptor (photoreceptor)
210 Film forming chamber 211 Exhaust port 212 Substrate rotation section 213 Substrate support member 214 Substrate 215 Gas introduction tube 216 Shower nozzle 217 Plasma diffusion section 218 High frequency power supply section 219 Flat electrode 220 Gas introduction tube 221 High frequency discharge tube section 222 High frequency coil 223 Quartz tube

Claims (10)

The oxygen O and the metal element in a layer comprising a conductive substrate, a photosensitive layer, and an inorganic protective layer containing a metal element M, oxygen O, and hydrogen H in this order, and forming a surface of the inorganic protective layer. An electrophotographic photoreceptor having an elemental composition ratio (oxygen O/metal element M) with M of 1.3 or more and 1.5 or less;
a charging device having a contact-type charging member that charges the surface of the electrophotographic photoreceptor; and an AC voltage application unit that applies an AC voltage to the contact-type charging member;
an electrostatic image forming device that forms an electrostatic image on the surface of the charged electrophotographic photoreceptor;
a developing device that supplies an electrostatic image developer to develop the electrostatic image formed on the surface of the electrophotographic photoreceptor as a toner image;
a transfer device that transfers the toner image formed on the surface of the electrophotographic photoreceptor to the surface of a recording medium;
An image forming apparatus comprising: 2. The elemental composition ratio of the oxygen O and the metal element M (oxygen O/metal element M) in the layer constituting the surface of the inorganic protective layer is 1.4 or more and 1.5 or less. Image forming device. The inorganic protective layer is a layer constituting the surface of the inorganic protective layer, in which the elemental composition ratio of the oxygen O and the metal element M (oxygen O/metal element M) is 1.3 or more and less than 1.5. The image forming apparatus according to claim 1 or 2, which is a single layer body. The image forming apparatus according to claim 3, wherein the thickness of the monolayer of the layer constituting the surface of the inorganic protective layer is 0.5 μm or more and 1.0 μm or less. Any one of claims 1 to 4, wherein the peak-to-peak voltage V _pp of the AC voltage applied to the contact-type charging member by the AC voltage applying section is 350 V or less and 4000 V or less, and the frequency is 100 Hz or more. The image forming apparatus described in . The image forming apparatus according to claim 5, wherein the peak-to-peak voltage _Vpp is 800V or more and 1500V or less, and the frequency is 2500Hz or more. The charging member is provided upstream in the rotational direction of the electrophotographic photoreceptor than the contact charging member, and includes a non-contact charging member that charges the surface of the electrophotographic photoreceptor, and a non-contact charging member that charges the surface of the electrophotographic photoreceptor. The image forming apparatus according to any one of claims 1 to 4, further comprising a DC voltage applying section that applies a DC voltage to the charging member. The peak-to-peak voltage V _pp of the AC voltage applied to the contact-type charging member by the AC voltage applying unit is 1000 V or more and 4000 V or less, and the frequency is 2500 Hz or more,
The image forming apparatus according to claim 7, wherein a voltage V of the DC voltage applied to the non-contact charging member by the DC voltage applying section is 600V or more and 1000V or less. The image forming apparatus according to claim 1, wherein the inorganic protective layer has a light transmittance of 90% or more. The oxygen O and the metal element in a layer comprising a conductive substrate, a photosensitive layer, and an inorganic protective layer containing a metal element M, oxygen O, and hydrogen H in this order, and forming a surface of the inorganic protective layer. An electrophotographic photoreceptor having an elemental composition ratio (oxygen O/metal element M) with M of 1.3 or more and 1.5 or less;
a charging device having a contact-type charging member that charges the surface of the electrophotographic photoreceptor; and an AC voltage application unit that applies an AC voltage to the contact-type charging member;
An image forming apparatus unit comprising: