JP5817615B2 - Electrophotographic photosensitive member, process cartridge, and image forming apparatus - Google Patents

Description

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

The electrophotographic method is widely used for copying machines, printers, and the like.
In recent years, regarding an electrophotographic photosensitive member (hereinafter sometimes referred to as “photosensitive member”) used in an image forming apparatus utilizing electrophotography, a surface layer (protective layer) is provided on the surface of the photosensitive layer of the photosensitive member. Technology is being considered.

  For example, Patent Document 1 states that “it is composed of a photoconductive layer made of a non-single crystal material having at least silicon atoms as a base material on a conductive substrate, and a non-single crystal material laminated on the photoconductive layer. In the electrophotographic photoreceptor having the surface layer formed, the surface layer has a first surface layer and a second surface layer, and at least a part of the surface layer layer contains oxygen atoms, An electrophotographic photoreceptor has been proposed in which the content distribution of oxygen atoms relative to the total amount of constituent atoms in the thickness direction has a peak in a region connecting the first surface layer and the second surface layer.

  Patent Document 2 states that “in an electrophotographic photosensitive member including a conductive substrate, a photosensitive layer, and a surface layer, and the photosensitive layer and the surface layer are laminated in this order on the conductive substrate, An electrophotographic photosensitive member in which at least the outermost surface contains oxygen and a group 13 element, and the oxygen content on the outermost surface exceeds 15 atomic%, and “the concentration distribution of oxygen contained in the surface layer in the thickness direction of the surface layer” Has been proposed for an electrophotographic photoreceptor that decreases toward the photosensitive layer side.

  Patent Document 3 states that “a protective layer containing oxygen and gallium, which is present on the outer peripheral surface side, on the side closer to the substrate than the first region, An electrophotographic photoreceptor having a protective layer having a second region in which the atomic ratio [oxygen / gallium] is larger than that in the above region has been proposed.

  Patent Document 4 states that “a first region existing on the outer peripheral surface side and a region closer to the substrate than the first region, and an atomic ratio [oxygen / gallium] compared to the first region”. A protective layer having a second region having a large area and a third region that is closer to the substrate than the second region and has a smaller atomic ratio [oxygen / gallium] than the second region. Provided, the light absorption edge energy in the first region is FE1, and the light absorption edge energy in the second region is the light absorption edge energy obtained from the wavelength at which the absorption coefficient is 1 × 10 6 (m−1) in each region. Is FE2, and the light absorption edge energy in the third region is FE3, the following relational expression (1): 0.5 eV ≦ FE2-FE1 ≦ 1.5 eV, relational expression (2): 0.5 eV ≦ FE2-FE3 ≦ 1.5 eV and relational expression (3): FE3 ≧ It has been proposed for the electrophotographic photosensitive member "to meet the E1.

  By the way, Patent Document 5 states that “a base gas can be obtained by introducing a reactive gas into a discharge space into a discharge space under atmospheric pressure or a pressure near atmospheric pressure, and exposing the base material to a reactive gas in a plasma state. In the transparent conductive film forming method for forming a transparent conductive film thereon, a method for forming a transparent conductive film characterized in that the reactive gas contains a reducing gas has been proposed.

JP 2006-163219 A JP 2006-267507 A JP 2011-028218 A JP 2011-197571 A JP 2003-234028 A

  An object of the present invention is to provide an electrophotographic photosensitive member that suppresses density unevenness of a halftone image having a low image density.

The above problem is solved by the following means. That is,
The invention according to claim 1
A substrate;
A photosensitive layer provided on the substrate;
A protective layer provided on the photosensitive layer and containing oxygen and gallium, the first region existing on the outer peripheral surface side, the first region existing closer to the substrate than the first region, A second region having a larger atomic ratio [oxygen / gallium] than that of the first region;
With
As each light absorption edge energy obtained from a wavelength having an absorption coefficient of 1 × 10 ⁶ (m ⁻¹ ) in each region, the average value of the light absorption edge energy in the first region [(maximum value + minimum value). / 2] is FE1, the average value [(maximum value + minimum value) / 2] of the light absorption edge energy in the second region is FE2, and the maximum value of the light absorption edge energy in the second region is FE2 (maximum. Value), an electrophotographic photosensitive member satisfying the following relational expressions (1) and (2), where FE2 (minimum value) is the minimum value of light absorption edge energy in the second region.
Relational expression (1): 0.5 eV ≦ FE2-FE1 ≦ 1.5 eV
Relational expression (2): FE2 (maximum value) −FE2 (minimum value) ≦ 0.5 eV

The invention according to claim 2
2. The electrophotographic photosensitive member according to claim 1, wherein the difference between the maximum value and the minimum value of the atomic ratio [oxygen / gallium] in the second region is 0.1 or less.

The invention according to claim 3
A protrusion on the outer peripheral surface of the protective layer;
3. The electrophotographic photosensitive member according to claim 1, wherein the maximum diameter of the protrusions is 2 μm or less, and the number of the protrusions per unit area of the outer peripheral surface of the protective layer is 5000 / mm ² or less. body.

The invention according to claim 4
The electrophotographic photosensitive member according to any one of claims 1 to 3,
A process cartridge that is detachable from the image forming apparatus.

The invention according to claim 5
An electrophotographic photosensitive member according to any one of claims 1 to 3,
Charging means for charging the electrophotographic photoreceptor;
Latent image forming means for forming a latent image on the surface of the charged electrophotographic photosensitive member;
Developing means for developing a latent image formed on the surface of the electrophotographic photosensitive member with toner to form a toner image;
Transfer means for transferring a toner image formed on the surface of the electrophotographic photosensitive member to a recording medium;
An image forming apparatus.

According to the first aspect of the present invention, in the electrophotographic photosensitive member provided with the protective layer having the first region and the second region, a low image is obtained as compared with the case where the relational expressions (1) and (2) are not satisfied. An electrophotographic photosensitive member that suppresses density unevenness of a halftone image of density can be provided.
According to the second aspect of the present invention, compared to the case where the difference between the maximum value and the minimum value of the atomic ratio [oxygen / gallium] in the second region exceeds 0.1, a halftone image with a low image density is obtained. An electrophotographic photosensitive member that suppresses density unevenness can be provided.
According to the invention of claim 3, the maximum diameter of the protrusions on the outer peripheral surface of the protective layer exceeds 2 μm, and the number per unit area of the outer peripheral surface of the protective layer of the protrusions exceeds 5000 / mm ² . Compared to the case, it is possible to provide an electrophotographic photosensitive member that suppresses density unevenness of a halftone image having a low image density.

  According to the inventions according to claims 4 and 5, an electrophotographic photosensitive member provided with a protective layer having a first region and a second region, and does not satisfy the relational expressions (1) and (2). As compared with the case where a photoconductor is applied, a process cartridge and an image forming apparatus that can suppress density unevenness of a halftone image having a low image density can be provided.

FIG. 3 is a schematic cross-sectional view illustrating an example of a layer configuration of the electrophotographic photosensitive member of the present embodiment. It is a schematic cross section showing another example of the layer configuration of the electrophotographic photosensitive member of the present embodiment. It is a schematic cross section showing another example of the layer configuration of the electrophotographic photosensitive member of the present embodiment. It is a schematic diagram showing an example of a film forming apparatus used for forming a protective layer of the electrophotographic photosensitive member of the present embodiment. It is a schematic diagram which shows the example of the plasma generator used for formation of the protective layer of the electrophotographic photoreceptor of this embodiment. It is a perspective view which shows the shower nozzle periphery in the film-forming apparatus used for formation of the protective layer of the electrophotographic photosensitive member of this embodiment. 1 is a schematic configuration diagram illustrating an example of an image forming apparatus according to an exemplary embodiment. It is a schematic block diagram which shows another example of the image forming apparatus which concerns on this embodiment.

  Hereinafter, embodiments of the electrophotographic photosensitive member, the process cartridge, and the image forming apparatus of the present invention will be described in detail.

<Electrophotographic photoreceptor>
The electrophotographic photoreceptor of this embodiment includes a substrate, a photosensitive layer provided on the substrate, and a protective layer provided on the photosensitive layer and containing oxygen and gallium.

The protective layer includes a first region present on the outer peripheral surface side, a second region closer to the substrate than the first region, and a second atomic ratio [oxygen / gallium] greater than that of the first region. And a region.
That is, the protective layer is present in the distribution of the atomic number ratio [oxygen / gallium] in the layer thickness direction, the first region existing on the outer peripheral surface side, the closer to the substrate than the first region, The second region has a larger atomic ratio [oxygen / gallium] than the first region, and the outer peripheral surface side of the electrophotographic photosensitive member has a structure in this order.
In other words, in the distribution of the atomic ratio [oxygen / gallium] in the thickness direction of the protective layer, the atomic ratio [oxygen / gallium] increases from the first region on the outer peripheral surface side (second region). The distribution reaches the photosensitive layer.
Note that the atomic ratio [oxygen / gallium] in the second region is larger than that in the first region means that the atomic ratio [oxygen / gallium] in the second region is larger than that in the first region. The average value [(maximum value + minimum value) / 2] of the sum of the minimum value and the minimum value is large.

And as each light absorption edge energy obtained from the wavelength with an absorption coefficient of 1 × 10 ⁶ (m ⁻¹ ) in each region, the average value of the light absorption edge energy in the first region [(maximum value + minimum value) / 2] is FE1, the average value [(maximum value + minimum value) / 2] of the light absorption edge energy in the second region is FE2, and the maximum value of the light absorption edge energy in the second region is FE2 (maximum value). When the minimum value of the light absorption edge energy in the second region is FE2 (minimum value), the following relational expressions (1) and (2) are satisfied.
Relational expression (1): 0.5 eV ≦ FE2-FE1 ≦ 1.5 eV
Relational expression (2): FE2 (maximum value) −FE2 (minimum value) ≦ 0.5 eV

In the electrophotographic photosensitive member according to the present embodiment, density unevenness of a low-tone halftone image is suppressed by the above configuration.
The reason for this is not clear, but is presumed to be as follows.

First, generally, when a protective layer containing oxygen and gallium is formed on the surface of the photosensitive layer of the electrophotographic photosensitive member, the sensitivity of the electrophotographic photosensitive member tends to decrease due to the formation of the protective layer. In particular, when the atomic ratio [oxygen / gallium] is decreased in the protective layer, the resistance of the layer is decreased, and the residual potential is decreased, the layer is colored due to light absorption in the entire visible region, and the sensitivity is greatly decreased. Tend.
By forming a region (first region) having a relatively small atomic ratio [oxygen / gallium] on the side away from the base of the region containing oxygen and gallium (second region), the protective layer is formed. A decrease in sensitivity is suppressed. The cause is presumed that the first region has a function as a charge injection region and the second region has a function as a charge transport region, so that the residual potential can be reduced and light absorption is reduced at the same time. Is done.
Therefore, when the electrophotographic photosensitive member has the configuration of the present embodiment, the protective layer has a second region having a larger atomic ratio [oxygen / gallium] than the first region present on the outer peripheral surface side. Compared with the case where the protective layer is not provided, a decrease in sensitivity due to the formation of the protective layer is suppressed.

On the other hand, the protective layer is composed of the first region and the second region, that is, the second layer having a larger atomic ratio [oxygen / gallium] than the first region on the photosensitive layer side of the protective layer. If the area is provided, the resolution of the image may be lowered. This phenomenon is considered to occur when the difference between the light absorption edge energy FE2 in the second region and the light absorption edge energy FE1 in the first region is too large.
For this reason, it is thought that the fall of the resolution of an image is suppressed when a protective layer satisfy | fills relational expression (1). Note that if the difference between the light absorption edge energy FE2 in the second region and the light absorption edge energy FE1 in the first region is too low, the light transmittance of the second region is too low and the sensitivity is likely to be lowered. Is improved when the protective layer satisfies the relational expression (1).

However, even if the decrease in the resolution of the image is suppressed, the light absorption edge energy is distributed in the second region having a larger atomic ratio [oxygen / gallium] than in the first region (direction along the surface of the protective layer). Distribution), density unevenness may occur depending on the distribution. This is thought to be due to the fact that when the difference between the maximum value and the minimum value of the light absorption edge energy has a distribution in the light absorption edge energy, there is a region where the resolution is partially different. This is presumed to be due to the partial differences in size. For this reason, in particular, this uneven density is a halftone image having a low image density (for example, 30% or less), in which dots constituting the image are formed apart and the difference in size is uneven and easily visible. When formed, it is considered to be prominent.
For this reason, it is considered that when the protective layer satisfies the relational expression (2), the density unevenness of the halftone image having a low image density is suppressed.

Note that, in the second region, the phenomenon having a distribution in the light absorption edge energy (distribution in a direction along the surface of the protective layer) is, for example, a known gas phase used for forming a protective layer containing oxygen and gallium. In the film forming method, it is likely to occur when the flow rate of the material gas (for example, trimethyl gallium gas) is increased to, for example, 2 sccm or more for the purpose of improving the productivity of the electrophotographic photosensitive member.
This is because when the flow rate of the material gas increases, the material gas reaches the photosensitive layer formed on the substrate in a state where the material gas does not diffuse, so the number of atoms is different between the region facing the material gas injection position and the other region. The ratio [oxygen / gallium] and the contents of hydrogen and carbon are different, which is considered to be formed so as to have a light absorption edge energy distribution.

  As described above, the electrophotographic photosensitive member according to the present embodiment satisfies the relational expression (1) after the protective layer having the first region and the second region satisfies the relational expression (2). Density unevenness of the density halftone image is suppressed.

Here, from the viewpoint of suppressing the density unevenness of the image, the difference between the light absorption edge energy FE2 in the second region and the light absorption edge energy FE1 in the first region is preferably 0.5 eV or more and 1.5 eV or less, More desirably, it is 0.8 eV or more and 1.4 eV or less.
From the same viewpoint, the difference between the light absorption edge energy FE2 (maximum value) and FE2 (minimum value) in the second region is 0.5 eV or less, preferably 0.4 eV or less, more preferably 0. 2 eV or less.

On the other hand, when the maximum value of the light absorption edge energy in the first region is FE1 (maximum value) and the minimum value of the light absorption edge energy in the second region is FE1 (minimum value), the light absorption in the first region. The difference between the end energy FE1 (maximum value) and FE1 (minimum value) is, for example, preferably 0.4 eV or less, desirably 0.3 eV or less, and more desirably 0.2 eV or less.
By setting the difference between the light absorption edge energy FE1 (maximum value) and FE1 (minimum value) in the first region, it is easy to suppress density unevenness due to a difference in sensitivity.

  Note that, in the first region and the second region, the maximum value and the minimum value of the light absorption edge energy are regions having different light absorption edge energies in the direction along the surface of the protective layer. Among the regions having different edge energies, the values of the region having the largest light absorption edge energy and the values of the region having the smallest light absorption edge energy are shown.

Each light absorption edge energy obtained from a wavelength at which the absorption coefficient is 1 × 10 ⁶ (m ⁻¹ ) in each region has a wavelength at which the absorption coefficient is 1 × 10 ⁶ (m ⁻¹ ) in the spectral spectrum. The wavelength is converted into energy (eV) as the wavelength.
Then, the maximum value and the minimum value of the light absorption edge energy in each region are obtained in accordance with the description in [Characteristic evaluation] described later.

Each light absorption edge energy obtained from a wavelength having an absorption coefficient of 1 × 10 ⁶ (m ⁻¹ ) in each region is a material gas (for example, trimethylgallium gas) or a process gas (for example, hydrogen gas) in film formation in each region. , Oxygen gas) flow rate, pressure during discharge, and discharge electric energy. In addition, each light absorption edge energy obtained from a wavelength having an absorption coefficient of 1 × 10 ⁶ (m ⁻¹ ) in each region is also controlled by the amount of impurities (for example, carbon atoms) in each region.
Further, in order to reduce the difference between the maximum value and the minimum value of the light absorption edge energy in each region, for example, the nozzle group of nozzles for injecting a material gas (for example, trimethylgallium gas) in film formation in each region A frame body is provided around the front end side (the side facing the substrate on which the photosensitive layer forming the protective layer is provided) having an elongated hole shape (slit shape), and after the material gas is injected from the nozzle , How to create a diffuse state in an unreacted state,

In the electrophotographic photoreceptor according to the exemplary embodiment, the difference between the maximum value and the minimum value of the atomic ratio [oxygen / gallium] in the second region is, for example, preferably 0.1 or less, and preferably 0. .05 or less.
By making the difference between the maximum value and the minimum value of the atomic ratio in the second region the above range, the difference between the light absorption edge energy FE2 (maximum value) and FE2 (minimum value) in the second region is reduced. As a result, the density unevenness of the low-tone halftone image is easily suppressed.

On the other hand, the difference between the maximum value and the minimum value of the atomic ratio [oxygen / gallium] in the first region is, for example, preferably 0.1 or less, and preferably 0.05 or less.
By making the difference between the maximum value and the minimum value of the atomic ratio in the second region the above range, the difference between the light absorption edge energy FE1 (maximum value) and FE1 (minimum value) in the first region is reduced. As a result, density unevenness due to a difference in sensitivity is easily suppressed.

  In the first region and the second region, there are regions having different atomic ratios in the direction along the surface of the protective layer, with the maximum value and the minimum value of the atomic ratio [oxygen / gallium], Of the regions with different atomic ratios, the values of the region with the highest atomic ratio and the values of the region with the lowest atomic ratio are shown.

In the electrophotographic photoreceptor according to the exemplary embodiment, the first region and the second region may have a clear interface with an adjacent region or an unclear interface with an adjacent region. Good.
Hereinafter, the first region when the interface with the adjacent region is clear is referred to as “first layer”, and the second region when the interface with the adjacent region is clear is referred to as “second layer”. "
That is, the protective layer is a first layer present on the outer peripheral surface side and is present on the side closer to the substrate than the first layer, and has a larger atomic ratio [oxygen / gallium] than the first layer. And two layers.

In addition, the atomic ratio [oxygen / gallium] is greater than or equal to the atomic ratio [oxygen / gallium] of the first layer between the first layer and the second layer, and the atomic ratio of the second layer. It may have a form having an intermediate layer of [oxygen / gallium] or less.
According to the form having the intermediate layer, an increase in residual potential and a decrease in sensitivity due to the formation of the protective layer are further reduced. This is presumed to be because the charge transport from the first layer to the second layer is more effectively performed.

In the electrophotographic photoreceptor according to the exemplary embodiment, the composition of the protective layer and the atomic number ratio [oxygen / gallium] include the distribution in the layer thickness direction and the direction along the surface of the layer, for example, Rutherford back scattering. Obtained by (RBS).
RBS uses, for example, NEC 3SDH Pelletron as an accelerator, CE & A RBS-400 as an end station, and 3S-R10 as a system. For analysis, the CE & A HYPRA program or the like is used.
The RBS measurement conditions are: He ++ ion beam energy is 2.275 eV, detection angle is 160 °, and Grazing Angle is 109 ° with respect to the incident beam.

Specifically, the RBS measurement is performed as follows.
First, a He ++ ion beam is incident on the sample perpendicularly, a detector is set at 160 ° with respect to the ion beam, and the backscattered He signal is measured. The composition ratio and the film thickness are determined from the detected energy and intensity of He. In order to improve the accuracy of obtaining the composition ratio and the 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 resolution and backscattering dynamics.
The number of He atoms back-scattered by the target atom is determined by 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 from the measured composition by calculation, and this is used to calculate the layer thickness. The density error is within 20%.

  Then, the maximum value and the minimum value of the atomic ratio [oxygen / gallium] in each region are obtained as described in [Characteristic Evaluation] described later.

Even when the second region and the first region are continuously formed on the photosensitive layer as in the present embodiment, the surface layer portion (the first region or the second region) is measured by the above measurement method. ), The elemental composition of each of the first region and the second region is measured.
Moreover, about content of each element in the whole protective layer, it measures by SIMS (secondary ion mass spectrometry), XPS (X-ray photoelectron spectroscopy), EDS (energy dispersive X-ray analysis), etc., for example. .

In the electrophotographic photoreceptor according to the exemplary embodiment, the protective layer has a protrusion on the outer peripheral surface, and the maximum diameter of the protrusion is 2 μm or less (desirably 1.0 μm or less, more desirably 0.5 μm or less), and The number per unit area of the outer peripheral surface of the protective layer of the protrusion may be 5000 / mm ² or less (preferably 3000 / mm ² or less, more desirably 1000 / mm ² or less).
Here, for the formation of the protective layer containing oxygen and gallium, for example, a known vapor phase film forming method is used, but during the film formation, particulate matter is generated and finally formed on the outer peripheral surface of the protective layer. In some cases, protrusions resulting from the generated granular material are scattered. The protrusions scattered on the outer peripheral surface of the protective layer cause a decrease in the resolution of the image, in particular, the occurrence of density unevenness in a halftone image having a low image density.
Therefore, by setting the maximum diameter of the protrusion on the outer peripheral surface of the protective layer within the above range and the number per unit area of the outer peripheral surface of the protective layer of the protrusion within the above range, it is possible to reduce the resolution of the image, particularly Further, density unevenness of the low-tone image halftone image is easily suppressed.

  In order to set the maximum diameter of the protrusions on the outer peripheral surface of the protective layer within the above range and the number per unit area of the outer peripheral surface of the protective layer of the protrusions within the above range, for example, when forming the protective layer , A method for suppressing the generation of particulate matter, specifically, the front end side (photosensitive film for forming a protective layer) around the nozzle outlet group for injecting a material gas (for example, trimethylgallium gas) in film formation in each region. A method of creating a state in which an unreacted state is diffused after a material gas is ejected from a nozzle by providing a frame having a slot-like (slit-like) opening on the side facing the substrate on which the layer is provided Can be mentioned,

  The maximum diameter of the protrusion on the outer peripheral surface of the protective layer and the number per unit area of the outer peripheral surface of the protective layer of the protrusion are determined according to the description in [Characteristic evaluation] described later.

In the electrophotographic photosensitive member according to the present embodiment, generally, when the protective layer is thickened, the durability as the electrophotographic photosensitive member is improved, but there is a tendency that the sensitivity is lowered due to the formation of the protective layer.
On the other hand, in this embodiment, as described above, the protective layer is suitable for a form in which the protective layer is thick in order to suppress a decrease in sensitivity due to the formation of the protective layer. That is, according to this embodiment, even when the layer thickness is increased, a decrease in sensitivity due to the formation of the protective layer is suppressed.
Therefore, the thickness of the protective layer is desirably 1.0 μm or more from the viewpoint of achieving both improvement in durability and suppression of reduction in sensitivity due to the formation of the protective layer. Furthermore, 1.5 μm or more is more desirable, 2.0 μm or more is further desirable, and 2.5 μm or more is particularly desirable.
The upper limit of the thickness of the protective layer is not particularly limited, but is 6.0 μm from the viewpoint of further reducing sensitivity reduction due to protective layer formation and residual potential increase.
As a method for confirming the durability of the electrophotographic photosensitive member, for example, a method for examining the presence or absence of scratches on the surface of the electrophotographic photosensitive member when image formation is repeatedly performed (the fewer the scratches, the higher the durability). .
Further, when the image formation is repeated, it may be checked whether the formed image has a white streak-like image defect due to a scratch on the surface of the electrophotographic photosensitive member (a white streak-like image defect). The smaller the number, the higher the durability.)

The second region is preferably thicker than the first region. Specifically, the thickness of the first region is preferably, for example, 500 nm or more and 2000 nm or less (desirably 1000 nm or more and 1500 nm or less). On the other hand, the thickness of the second region is preferably, for example, 500 nm or more and 5500 nm or less (desirably 1000 nm or more and 1500 nm or less).
When the thickness of each region is in the above range, density unevenness of a halftone image with low image density is easily suppressed.

−Configuration of electrophotographic photosensitive member−
Hereinafter, the configuration of the electrophotographic photoreceptor according to the present exemplary embodiment will be described with reference to FIGS. 1 to 3, but the exemplary embodiment is not limited to FIGS. 1 to 3.
FIG. 1 is a schematic cross-sectional view showing an example of the layer structure of the electrophotographic photosensitive member according to the present embodiment.
In FIG. 1, 1 is a substrate, 2 is a photosensitive layer, 2A is a charge generation layer, 2B is a charge transport layer, 3 is a protective layer, 3A is a first region, and 3B is a second region. 4 is an undercoat layer.
1 has a layer structure in which an undercoat layer 4, a charge generation layer 2A, a charge transport layer 2B, and a protective layer 3 are laminated in this order on a substrate 1, and the photosensitive layer 2 is a charge generation layer. 2A and the charge transport layer 2B.
The protective layer 3 includes a first region 3A that exists on the outer peripheral surface side, and a second region 3B that exists on the side closer to the base 1 than the first region 3A.
In FIG. 1, for the sake of illustration, the boundary between the first region 3A and the second region 3B is clear (that is, the first region 3A is the first layer, and the second region 3B). Is the second layer), but this boundary is not limited to being clear. The same applies to the boundary between the first region 3A and the second region 3B in FIG. 2 and FIG.

FIG. 2 is a schematic cross-sectional view showing another example of the layer configuration of the electrophotographic photosensitive member according to this embodiment. In FIG. 2, 6 represents a photosensitive layer, and the others are the same as those shown in FIG. It is the same.
2 has a layer structure in which an undercoat layer 4, a photosensitive layer 6, and a protective layer 3 are laminated in this order on a substrate 1, and the photosensitive layer 6 includes a charge generation layer 2A shown in FIG. In addition, the charge transport layer 2B has an integrated function.
The photosensitive layer 2 and the photosensitive layer 6 may be formed from an organic polymer, may be formed from an inorganic material, or may be a combination thereof.

FIG. 3 is a schematic cross-sectional view showing another example of the layer structure of the electrophotographic photosensitive member according to the present embodiment. In FIG. 3, 3 is a protective layer, 3D is a first layer, and 3E is a second layer. 3G represents an intermediate layer, and the others are the same as those shown in FIG.
The photoreceptor shown in FIG. 3 has a layer structure in which an undercoat layer 4, a photosensitive layer 2, a second layer 3E, an intermediate layer 3F, and a first layer 3D are laminated in this order on a substrate 1. .
The protective layer 3 includes a first layer 3D existing on the outer peripheral surface side, a second layer 3E existing closer to the substrate 1 than the first layer 3D, a first layer 3D, and a second layer 3E. The intermediate layer 3G exists between the two.

  Hereinafter, a protective layer, a photosensitive layer, and a substrate, which are components of the electrophotographic photosensitive member according to this embodiment, will be described. Note that the reference numerals are omitted.

-Protective layer-
As described above, the protective layer is a layer containing oxygen (O) and gallium (Ga), and is a layer provided further on the photosensitive layer provided on the substrate.
The protective layer, for example, suppresses scratches on the surface of the electrophotographic photoreceptor, suppresses polishing variations, suppresses adsorption of nitrogen oxides, and improves resistance to an oxidizing atmosphere caused by ozone or nitrogen oxides. It is a layer provided for the purpose. The protective layer is desirably a highly transparent and dense film with excellent hardness.
The protective layer may trap surface charges on the surface or trap them inside. Further, a surface charge may be positively injected. In the case of injecting charges into the protective layer, it is desirable to have a configuration in which charges are trapped at the interface with the organic photosensitive layer. Further, when the surface layer injects electrons under negative charge, the surface of the hole transport layer may serve as a charge trapping function, or a layer for blocking and trapping charge injection may be provided. The same configuration is applied to the case of positive charging.

The protective layer is preferably a non-single crystal film such as a microcrystalline film, a polycrystalline film, or an amorphous film containing oxygen (O) and gallium (Ga).
Among these, amorphous 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 protective layer may have a columnar structure, but from the viewpoint of slipperiness, a structure with high flatness is desirable and amorphous is desirable.
In order to improve surface slipping while improving adhesion to the photosensitive layer, the region on the interface side with the photosensitive layer (for example, the second region) is a microcrystalline film, and the region on the surface side (for example, the first region) 1 region) may be an amorphous film.

  The protective layer may further contain one or more elements selected from C, Si, Ge, and Sn, for example, in the case of n-type, for control of the conductivity type. For example, in the case of p-type, it may contain one or more elements selected from N, Be, Mg, Ca, and Sr.

The protective layer desirably contains at least one of hydrogen and a halogen element in addition to oxygen (O) and gallium (Ga).
When the protective layer is microcrystalline, polycrystalline, or amorphous, there is a tendency for bond defects, dislocation defects, crystal grain boundary defects, etc. to increase, but by including hydrogen or a halogen element in the layer, This is desirable because the bonding defects are deactivated.
Hydrogen and halogen elements are taken into bond defects in the crystal and defects at the crystal grain boundaries, and perform electrical compensation. For this reason, the number of traps related to the generation of photocarriers, the diffusion and movement of carriers is reduced, the number of reactive sites is reduced, and a more stable protective layer is formed.
The content of “at least one of hydrogen and halogen elements” in the protective layer is preferably 5 atom% or more and 25 atom% or less, and more preferably 10 atom% or more and 25 atom% or less.

The content of hydrogen in the protective layer is determined by measuring an absolute value by hydrogen forward scattering (HFS), for example. Moreover, you may estimate by an infrared absorption spectrum.
HFS uses NEC 3SDH Pelletron as an accelerator, CE & A RBS-400 as an end station, and CE & A 3S-R10 as a system.
The analysis uses the CE & A HYPRA program.

The measurement conditions of HFS are as follows.
He ++ ion beam energy: 2.275 eV
A detection angle of 160 ° is Grazing Angle 30 ° with respect to the incident beam.

The HFS measurement picks up the hydrogen signal scattered in front of the sample by setting the detector at 30 ° to the He ++ ion beam and the sample at 75 ° from the normal. At this time, the detector is preferably covered with aluminum foil to remove He atoms scattered together with hydrogen. The quantification is performed by comparing the hydrogen counts of the reference sample and the sample to be measured after normalization with the stopping power. As a reference sample, a sample obtained by ion-implanting H into Si and muscovite are used.
It is known that muscovite has a hydrogen concentration of 6.5 atomic%.
The H adsorbed on the outermost surface is corrected by subtracting the amount of H adsorbed on the clean Si surface, for example.

--First region--
A 1st area | region is an area | region which exists in an outer peripheral surface side (side away from the support body) in the film thickness direction among protective layers.
The first region is a composition containing gallium and oxygen.

  The atomic ratio [oxygen / gallium] in the first region is desirably 1.10 or more and 1.35 or less, and more desirably 1.20 or more and 1.35 or less. The atomic ratio of the first region is an average value [(maximum value + minimum value) / 2] of the sum of the maximum value and the minimum value of the atomic ratio [oxygen / gallium] of the first region. is there.

The first region may contain hydrogen from the viewpoint of more effectively reducing the decrease in sensitivity of the photoreceptor.
The hydrogen content in the first region is preferably 5 atomic percent or more and 25 atomic percent or less, and more preferably 10 atomic percent or more and 25 atomic percent or less.
In addition, the desirable form of the first region is as described above as the desirable form of the protective layer.

As described above, the first region may contain an n-type element or a p-type element for controlling the conductivity type. In this case, the first region may be a charge injection blocking layer. Alternatively, a charge injection layer may be used. In the case of the charge injection layer, charges are trapped in the second region and the photosensitive layer surface.
In the case of negative charging, the n-type layer functions as a charge injection layer, and the p-type layer functions as a charge injection blocking layer. In the case of positive charging, the n-type layer functions as a charge injection blocking layer, and the p-type layer functions as a charge injection layer.

-Second region-
The second region is a region of the protective layer that is closer to the substrate than the first region, and has a larger atomic ratio [oxygen / gallium] than the first region.
As described above, the composition of the second region is a composition containing gallium and oxygen (and zinc if necessary).

In the second region, the atomic ratio [oxygen / gallium] is preferably 1.30 or more and 1.50 or less, and more preferably 1.40 or more and 1.50 or less. The atomic ratio of the second region is an average value [(maximum value + minimum value) / 2] of the sum of the maximum value and the minimum value of the atomic ratio [oxygen / gallium] of the second region. is there.
If the atomic ratio [oxygen / gallium] in the second region is within this range, coloring of the second region is suppressed (that is, transparency is improved), and a wavelength region from ultraviolet to infrared (for example, , The light transmittance in a wavelength region of 350 nm to 800 nm is easily improved. As a result, the absorption of the light in the protective layer is suppressed when light is irradiated from the outside of the photoconductor in order to eliminate the charge of the charged electrophotographic photoconductor. Therefore, since the irradiated light efficiently reaches the photosensitive layer, the sensitivity of the electrophotographic photosensitive member is easily improved.
Even when the atomic ratio [oxygen / gallium] in the second region is 1.30 or more and 1.50 or less, the first region described above exists on the side farther from the base than the second region. Therefore, the residual potential is suppressed as described above.

It is desirable that the second region further contains zinc (Zn).
When the second region contains zinc, a decrease in sensitivity is further suppressed, and the residual potential is further suppressed.
About this cause, it is estimated that the charge transport property of the second region is improved by containing zinc in the second region.
From the viewpoint of suppressing the residual potential, the zinc content in the second region is preferably 0.4 atomic percent or more and 25 atomic percent or less, and more preferably 0.5 atomic percent or more and 20 atomic percent or less. It is particularly desirable that it is 10 atomic% or more and 20 atomic% or less.
Here, the zinc content in the second region is the ratio (%) of the number of zinc atoms to the total number of atoms when the second region is composed of gallium, oxygen, and zinc. .
Further, from the viewpoint of suppressing the decrease in sensitivity, the atomic ratio [zinc / gallium] in the second region is preferably 1.00 or less, more preferably 0.01 or more and 0.50 or less, It is particularly desirable that it is 0.20 or more and 0.50 or less. The atomic ratio of the second region is the average value [(maximum value + minimum value) / 2] of the sum of the maximum value and the minimum value of the atomic ratio [zinc / gallium] of the second region. is there.
Further, from the viewpoint of suppressing the decrease in sensitivity, the zinc content in the second region is desirably 0.4 atomic% or more and 25 atomic% or less, and is 0.5 atomic% or more and 20 atomic% or less. Is more desirable, and it is particularly desirable that it is 1 atomic% or more and 15 atomic% or less.

The second region may further contain hydrogen from the viewpoint of more effectively reducing the decrease in sensitivity of the photoreceptor.
The hydrogen content in the second region is preferably 5 atomic percent or more and 25 atomic percent or less, and more preferably 10 atomic percent or more and 25 atomic percent or less.
In addition, the desirable form of the second region is as described above as the desirable form of the protective layer.

--Intermediate layer--
The intermediate layer is a layer provided as necessary in the protective layer, and when the protective layer includes the first layer and the second layer, between the first layer and the second layer, This is a layer provided with a composition in which the atomic ratio [oxygen / gallium] is not less than the atomic ratio [oxygen / gallium] of the first layer and not more than the atomic ratio [oxygen / gallium] of the second layer.
The composition of the intermediate layer is a composition containing gallium and oxygen (and zinc if necessary).
The intermediate layer may further contain hydrogen from the viewpoint of more effectively reducing the decrease in sensitivity of the photoreceptor.
The content of hydrogen in the intermediate layer is preferably 5 atomic percent or more and 25 atomic percent or less, and more preferably 10 atomic percent or more and 25 atomic percent or less.
In addition, the desirable form of the intermediate layer is as described above as the desirable form of the protective layer.

  In addition to the first region, the second region, and the intermediate layer, the protective layer may have other layers or regions as necessary.

-Method for forming protective layer-
Next, a method for forming the protective layer described above will be described.
For the formation of the protective layer, a known vapor deposition method such as a plasma CVD (Chemical Vapor Deposition) method, a metal organic vapor phase epitaxy method, a molecular beam epitaxy method, vapor deposition, or sputtering is used.

  FIG. 4 is a schematic diagram showing an example of a film forming apparatus used for forming the protective layer of the electrophotographic photosensitive member according to the present embodiment. FIG. 4A is a view of the film forming apparatus when viewed from the side. A schematic cross-sectional view is shown, and FIG. 4B is a schematic cross-sectional view taken along line A1-A2 of the film formation apparatus shown in FIG. In FIG. 4, 210 is a film forming chamber, 211 is an exhaust port, 212 is a substrate rotating unit, 213 is a substrate support member, 214 is a substrate, 215 is a gas introduction pipe, and 216 is a gas introduced from a gas introduction pipe 215. A shower nozzle having a group of nozzle holes 216A, 217 is a plasma diffusion section, 218 is a high-frequency power supply section, 219 is a plate electrode, 220 is a gas introduction tube, and 221 is a high-frequency discharge tube section.

In the film forming apparatus shown in FIG. 4, an exhaust port 211 connected to a vacuum exhaust device (not shown) is provided at one end of the film forming chamber 210, and the side on which the exhaust port 211 of the film forming chamber 210 is provided. On the opposite side, a plasma generator comprising a high-frequency power supply unit 218, a plate electrode 219, and a high-frequency discharge tube unit 221 is provided.
This plasma generator is arranged in a high frequency discharge tube portion 221, a high frequency discharge tube portion 221, a flat plate electrode 219 having a discharge surface provided on the exhaust port 211 side, a high frequency discharge tube portion 221 and a flat plate. The high-frequency power supply unit 218 is connected to the surface of the electrode 219 opposite to the discharge surface. The high-frequency discharge tube portion 221 is connected to a gas introduction tube 220 for supplying gas into the high-frequency discharge tube portion 221, and the other end of the gas introduction tube 220 is a first not shown. Connected to the gas supply.

  Note that the plasma generator shown in FIG. 5 may be used instead of the plasma generator provided in the deposition apparatus shown in FIG. FIG. 5 is a schematic diagram showing another example of the plasma generator used in the film forming apparatus shown in FIG. 4, and is a side view of the plasma generator. In FIG. 5, 222 is a high frequency coil, 223 is a quartz tube, and 220 is the same as that shown in FIG. This plasma generator comprises a quartz tube 223 and a high-frequency coil 222 provided along the outer peripheral surface of the quartz tube 223, and one end of the quartz tube 223 is a film forming chamber 210 (not shown in FIG. 5). It is connected. 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. The introduction pipe 215 is connected to a second gas supply source (not shown) provided outside the film formation chamber 210.
In addition, a substrate rotating unit 212 is provided in the film forming chamber 210, and the substrate supporting member is arranged so that the cylindrical substrate 214 faces along the longitudinal direction of the shower nozzle 216 and the axial direction of the substrate 214. It can be attached to the base rotating part 212 via 213. During film formation, the substrate 214 rotates in the circumferential direction by rotating the substrate rotating unit 212. As the substrate 214, for example, a photoconductor previously laminated up to the photosensitive layer, a photoconductor laminated up to the second region on the photosensitive layer, or the like is used.

  Here, around the group of nozzle holes 216A (injection ports) arranged at intervals in the longitudinal direction of the shower nozzle 216 for injecting a material gas (for example, trimethylgallium gas) for forming the protective layer, As shown in FIG. 6, a frame 224 having an elongated hole (slit) opening 224A is provided on the substrate 214 (substrate on which the photosensitive layer is formed). Specifically, for example, the material gas sprayed from the nozzle hole 216A of the shower nozzle 216 is covered so as to be shielded from plasma, and the frame body is sprayed from an elongated hole-shaped (slit-shaped) opening 224A. 224 is provided. As a result, the material gas is ejected from the nozzle hole 216A of the shower nozzle 216, shielded from plasma by the wall of the frame body 224, diffused in an unreacted state, and then has an elongated hole shape (slit shape). It is ejected from the opening 224A and reaches the substrate 214 (substrate on which the photosensitive layer is formed). That is, since the material gas is diffused in an unreacted state after being injected from the nozzle hole 216A, even if the flow rate of the material gas is increased, the photosensitive material formed on the substrate in a state where the material gas is diffused. Reach the layer. As a result, the atomic ratio [oxygen / gallium] is unlikely to differ between the region facing the material gas injection position and the other regions, and the distribution of the atomic ratio and the light absorption edge energy is suppressed, thereby protecting the region. It is considered that a layer (each region) is easily formed.

The protective layer is formed as follows, for example.
First, oxygen gas (or helium (He) diluted oxygen gas), hydrogen (H ₂ ) gas, and if necessary helium (He) gas are introduced into the high-frequency discharge tube portion 221 from the gas introduction tube 220, A radio wave of 13.56 MHz is supplied from the high frequency power supply unit 218 to the plate electrode 219. At this time, the plasma diffusion portion 217 is formed so as to spread radially from the discharge surface side of the plate electrode 219 to the exhaust port 211 side. Here, the gas introduced from the gas introduction pipe 220 flows through the film forming chamber 210 from the plate electrode 219 side to the exhaust port 211 side. The plate electrode 219 may be one in which the electrode is surrounded by a ground shield.
Next, trimethylgallium gas is introduced into the film formation chamber 210 through a gas introduction pipe 215 and a shower nozzle 216 located downstream of the plate electrode 219 serving as an activating means. A non-single crystal film containing is formed.
As the substrate 214, for example, a substrate on which a photosensitive layer is formed is used.
When forming the second region containing zinc as the second region, for example, trimethylgallium gas and organic zinc (for example, dimethylzinc or diethyl) are used as the gas introduced from the gas introduction pipe 215. Zinc) gas. At this time, trimethylgallium and organic zinc are introduced into the gas introduction pipe 215 as gases from separate containers.

When the organic photoreceptor having the organic photosensitive layer is used, the temperature of the surface of the substrate 214 when forming the 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 less at the beginning of film formation, if the temperature is higher than 150 ° C. due to the influence of plasma, the organic photosensitive layer may be damaged by heat. Thus, it is desirable to control the surface temperature of the substrate 214.
When an amorphous silicon photoconductor is used, the temperature of the surface of the substrate 214 when the protective layer is formed is, for example, 30 ° C. or higher and 350 ° C. or lower.
The temperature of the surface of the substrate 214 may be controlled by heating and / or cooling means (not shown in the figure), or may be left to a natural temperature increase during discharge. In the case of heating the base 214, a heater may be installed outside or inside the base 214. When the substrate 214 is cooled, a cooling gas or liquid may be circulated inside the substrate 214.
In order to avoid an increase in the temperature of the surface of the substrate 214 due to electric discharge, it is effective to adjust a high-energy gas flow that strikes the surface of the substrate 214. In this case, conditions such as the gas flow rate, discharge output, and pressure are adjusted so as to achieve the required temperature.

Further, instead of trimethylgallium gas, hydrides such as organometallic compounds containing aluminum and diborane may be used, and two or more of these may be mixed.
For example, in the initial stage of forming the protective layer, trimethylindium is introduced into the deposition chamber 210 through the gas introduction pipe 215 and the shower nozzle 216, thereby forming a film containing nitrogen and indium on the substrate 214. For example, this film absorbs ultraviolet rays that are generated when the film is continuously formed and deteriorate the photosensitive layer. For this reason, damage to the photosensitive layer due to generation of ultraviolet rays during film formation is suppressed.

Further, a dopant may be added to the protective layer in order to control its conductivity type.
As a dopant doping method during film formation, SiH ₃ and SnH ₄ are used for n-type, and biscyclopentadienylmagnesium, dimethylcalcium, dimethylstrontium, etc. are used in a gas state for p-type. . 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 formation chamber 210 via the gas introduction pipe 215 and the shower nozzle 216, a conductive type such as n-type or p-type is used. Get a protective layer.

In the film formation apparatus described with reference to FIGS. 4 and 5, active nitrogen or active hydrogen formed by discharge energy may be controlled independently by providing a plurality of active apparatuses, or with nitrogen atoms such as NH _3. You may use the gas which contains a hydrogen atom simultaneously. Further, H ₂ may be added. Alternatively, conditions under which active hydrogen is liberated from an organometallic compound may be used.
By doing so, activated carbon atoms, gallium atoms, nitrogen atoms, hydrogen atoms, and the like exist on the surface of the substrate 214 in a controlled state. Then, the activated hydrogen atom has an effect of desorbing hydrogen of a hydrocarbon group such as a methyl group or an ethyl group constituting the organometallic compound as a molecule.
For this reason, a hard film (protective layer) constituting a three-dimensional bond is formed.

The plasma generating means of the film forming apparatus shown in FIGS. 4 and 5 uses a high-frequency oscillator, but is not limited to this. For example, a microwave oscillator or an electrocyclotron resonance method is used. Alternatively, a helicon plasma type apparatus may be used. Further, in the case of a high-frequency oscillation device, it may be inductive or capacitive.
Furthermore, two or more of these devices may be used in combination, or two or more of the same types of devices may be used. In order to suppress the temperature rise on the surface of the substrate 214 by plasma irradiation, a high-frequency oscillation device is desirable, but a device for suppressing heat irradiation may be provided.

  When two or more different plasma generators (plasma generating means) are used, it is desirable that discharges are generated simultaneously at the same pressure. In addition, a pressure difference may be provided between the discharge area and the film formation area (the portion where the base is installed). These apparatuses may be arranged in series with respect to the gas flow formed in the film forming apparatus from the part where the gas is introduced to the part where the gas is discharged. You may arrange | position so that it may oppose.

For example, when two types of plasma generating means are installed in series with respect to the gas flow, the film forming apparatus shown in FIG. 4 is taken as an example, and a discharge is caused in the film forming chamber 210 using the shower nozzle 216 as an electrode. 2 is used as a 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 substrate 214 and the plate electrode 219 in the film forming chamber 210, and this film is used to form the film forming chamber 210. Causes a discharge inside.
In addition, when two different types of plasma generators are used 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, and the film quality can be controlled. It is valid. Moreover, you may perform discharge by atmospheric pressure vicinity (70000 Pa or more and 110000 Pa or less). When discharging near atmospheric pressure, it is desirable to use He as a carrier gas.

In forming the protective layer, in addition to the above-described methods, a normal metal organic vapor phase epitaxy method or molecular beam epitaxy method is used. Use of hydrogen and active oxygen is effective for lowering the temperature. In this case, as the nitrogen raw material, a gas or liquid such as N ₂ , NH ₃ , NF ₃ , N ₂ H ₄ , or methyl hydrazine is vaporized or bubbled with a carrier gas. As the oxygen raw material, oxygen, H ₂ O, CO, CO ₂ , NO, N ₂ O, or the like is used.

The protective layer is formed, for example, by placing a base 214 having a photosensitive layer formed on the base in the film forming chamber 210 and introducing mixed gases having different compositions to continuously form the second region and the first region. To form. Further, an intermediate layer is formed between the second region and the first region as necessary.
Further, each region (or each layer) may be formed independently.

As film formation conditions, for example, when discharging is performed by high-frequency discharge, it is desirable that the frequency be in the range of 10 kHz to 50 MHz in order to perform high-quality film formation at a low temperature. Further, the output is dependent on the size of the substrate, it is desirable to 0.05 W / cm ² or more 0.5 W / cm ² or less in the range of the surface area of the substrate. The rotation speed of the substrate is preferably in the range of 10 rpm to 1000 rpm.
The film formation conditions for each region (or each layer) may be the same. For example, the second region may be formed at a low temperature so that the output is low and the output of the first region is increased. Good.

-Substrate and photosensitive layer-
The photosensitive layer is a layer provided between the substrate and the protective layer in the electrophotographic photosensitive member.
The electrophotographic photoreceptor according to the exemplary embodiment is not particularly limited as long as the layer configuration is such that a photosensitive layer and a protective layer are laminated in this order on a substrate, and if necessary, between the substrate and the photosensitive layer. An undercoat layer or the like may be provided. Further, the photosensitive layer may be two or more layers, and further may be a function separation type. Furthermore, the electrophotographic photoreceptor according to the present embodiment may be a so-called amorphous silicon photoreceptor in which the photosensitive layer contains silicon atoms.

In the case of an amorphous silicon photoreceptor, if the protective layer in the present embodiment is used as the surface layer portion, image blur at high humidity is suppressed, and both durability and high image quality are achieved.
In particular, the photosensitive layer is desirably a so-called organic photoreceptor containing an organic material such as an organic photosensitive material. In the case of an organic photoreceptor, wear is likely to occur. However, if the protective layer in this embodiment is used for the surface layer portion, wear is suppressed.

First, an outline of a desirable configuration when the electrophotographic photoreceptor is an organic photoreceptor will be described.
The organic polymer compound forming the photosensitive layer may be thermoplastic or thermosetting, or may be formed by reacting two types of molecules. The second region provided between the photosensitive layer and the first region is characterized by the physical properties of the first region and the photosensitive layer (functional separation) from the viewpoints of adjustment of hardness, expansion coefficient, elasticity, and adhesion. In the case of a mold, those showing intermediate characteristics with respect to both physical properties of the charge transport layer) are preferred. Further, the second region may function as a region for trapping charges.

  In the case of an organic photoreceptor, the photosensitive layer may be a function-separated type that is divided into a charge generation layer and a charge transport layer as shown in FIGS. 1 and 3, or a function-integrated type as shown in FIG. May be. In the case of the function separation type, a charge generation layer may be provided on the surface side of the photoreceptor, or a charge transport layer may be provided on the surface side.

When the protective layer is formed on the photosensitive layer by the above-described method, in order to prevent the photosensitive layer from being decomposed by irradiation with short wavelength electromagnetic waves other than heat, the surface of the photosensitive layer is formed before the protective layer is formed. A short wavelength light absorption layer such as ultraviolet rays may be provided in advance. In addition, a layer having a small band gap may be formed first in the initial stage of forming the protective layer so that the short wavelength light is not irradiated onto the photosensitive layer. As the composition of the layer having a small band gap provided on the photosensitive layer side, for example, the group 13 element ratio including In is preferably Ga _X In _(1-X) (0 ≦ X ≦ 0.99).

In addition, a layer containing an ultraviolet absorber (for example, a layer formed by coating a layer dispersed in a polymer resin) may be provided on the surface of the photosensitive layer.
As described above, by providing a layer containing an ultraviolet absorber on the surface of the photosensitive member before forming the protective layer, ultraviolet rays when forming the protective layer and corona when the photosensitive member is used in the image forming apparatus are used. The influence on the photosensitive layer due to short wavelength light such as electric discharge or ultraviolet rays from various light sources is reduced.

Next, an outline of a desirable configuration when the electrophotographic photoreceptor is an amorphous silicon photoreceptor will be described.
The amorphous silicon photoconductor may be a positively charged or negatively charged photoconductor.
For example, a substrate in which a charge injection blocking layer (undercoat layer), a photoconductive layer, and a charge injection blocking surface layer are provided in this order on a substrate is used.
The protective layer in this embodiment is formed on the charge injection blocking surface layer.

Further, as the uppermost layer (protective layer side layer) of the photosensitive layer, for example, a p-type amorphous silicon layer, an n-type amorphous silicon layer, Si _X O _1-X : H layer, Si _X N _1-X : H layer , Si _X C _1-X : H layer, amorphous carbon layer, and the like are used.

  Next, regarding the details of the substrate and the photosensitive layer constituting the electrophotographic photoreceptor and the details of the undercoat layer provided as necessary, the electrophotographic photoreceptor is an organic photoreceptor having a function-separated type photosensitive layer. Will be described.

-Substrate-
A conductive substrate is used as the substrate.
In this specification, “conductive” refers to the property of having a volume resistivity of less than 10 ¹³ Ω · cm, and “insulating” refers to the property of having a volume resistivity of 10 ¹³ Ω · cm or more. Point to.
As the conductive substrate, a metal drum such as aluminum, copper, iron, stainless steel, zinc, nickel, etc .; on a substrate such as sheet, paper, plastic, glass, aluminum, copper, gold, silver, platinum, palladium, titanium, nickel- Deposited metal such as chromium, stainless steel, copper-indium, etc .; Deposited conductive metal compound such as indium oxide and tin oxide on the base; Laminated metal foil on the base; Carbon black, Indium oxide , Tin oxide-antimony oxide powder, metal powder, copper iodide and the like are dispersed in a binder resin and applied to the substrate to conduct a conductive treatment. The shape of the substrate is preferably a cylindrical shape.

  When a metal pipe base is used as the conductive base, the surface of the metal pipe base may be a raw pipe, but the base surface may be roughened by surface treatment in advance. . Due to such roughening, when a coherent light source such as a laser beam is used as the exposure light source, grain-like density unevenness due to interference light that can be generated inside the photosensitive member is suppressed. Examples of the surface treatment method include mirror cutting, etching, anodizing, rough cutting, centerless grinding, sand blasting, wet honing and the like.

  In particular, it is desirable to use an anodized surface of the aluminum substrate as the conductive substrate in terms of improving adhesion to the photosensitive layer and improving film formability.

Hereinafter, a method for producing a conductive substrate having an anodized surface will be described.
First, pure aluminum or aluminum alloy (for example, alloy numbers 1000, 3000, and 6000 series aluminum or aluminum alloy defined in JISH4080) is prepared as a substrate. Next, an anodizing process is performed. The anodizing treatment is performed in an acidic bath of chromic acid, sulfuric acid, oxalic acid, phosphoric acid, boric acid, sulfamic acid, etc., and a treatment using a sulfuric acid bath is often used. The anodizing treatment is, for example, sulfuric acid concentration: 10 mass% to 20 mass%, bath temperature: 5 ° C. to 25 ° C., current density: 1 A / dm ^{2 to} 4 A / dm ² and electrolysis voltage: 5 V to 30 V. The treatment time is 5 to 60 minutes, but is not limited thereto.

  The anodized film formed on the aluminum substrate in this way is porous, has high insulating properties, and has a very unstable surface. Therefore, its physical properties change over time after the film is formed. It has become easier. In order to suppress the change in the physical property value, the anodized film is further subjected to a sealing treatment. Examples of the sealing treatment include a method of immersing the anodized film in an aqueous solution containing nickel fluoride and nickel acetate, a method of immersing the anodized film in boiling water, and a method of treating with pressurized steam. Of these methods, the method of immersing in an aqueous solution containing nickel acetate is most often used.

  On the surface of the anodic oxide film that has been subjected to the sealing treatment in this way, an excessive amount of metal salt or the like attached by the sealing treatment remains. If the metal salt or the like is excessively left on the anodic oxide film of the substrate, it not only adversely affects the quality of the coating film formed on the anodic oxide film, but generally tends to leave low resistance components. When an image is formed using this substrate as a photoconductor, it causes a background stain.

  Therefore, following the sealing process, an anodic oxide film is cleaned to remove metal salts and the like attached by the sealing process. The cleaning treatment may be performed by cleaning the substrate once with pure water, but it is desirable to clean the substrate by a multi-step cleaning process. At this time, for example, a deionized cleaning liquid is used as the cleaning liquid in the final cleaning step. Moreover, it is more desirable to perform physical rubbing cleaning using a contact member such as a brush in any one of the multi-step cleaning processes.

  The film thickness of the anodized film on the surface of the conductive substrate formed as described above is preferably in the range of about 3 μm to 15 μm. On the anodized film, there is a layer called a barrier layer along the porous extreme surface of the porous anodized film. The film thickness of the barrier layer is preferably in the range of 1 nm to 100 nm in the electrophotographic photosensitive member according to the present embodiment. As described above, an anodized conductive substrate is obtained.

  The conductive substrate thus obtained has a high carrier blocking property in the anodized film formed on the substrate by anodization. For this reason, point defects (black spots, background stains) that occur when reversal development (negative / positive development) is performed with a photoconductor using this conductive substrate mounted on an image forming apparatus are suppressed, and contact charging is performed. Current leakage from the contact charger, which sometimes occurs, is suppressed. In addition, by subjecting the anodized film to a sealing treatment, changes in the physical property values with time after the preparation of the anodized film are suppressed. Further, by cleaning the conductive substrate after the sealing treatment, the metal salt or the like attached to the surface of the conductive substrate is removed by the sealing treatment, and an image is provided with a photoconductor produced using this conductive substrate. When an image is formed by the apparatus, the occurrence of background stains is suppressed.

-Undercoat layer-
Next, the undercoat layer will be described. The material constituting the undercoat layer is acetal resin such as polyvinyl butyral; polyvinyl alcohol resin, casein, polyamide resin, cellulose resin, gelatin, polyurethane resin, polyester resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinyl acetate In addition to polymer resin compounds such as resin, vinyl chloride-vinyl acetate-maleic anhydride resin, silicone resin, silicone-alkyd resin, phenol-formaldehyde resin, melamine resin, zirconium, titanium, aluminum, manganese, silicon atoms, etc. Examples thereof include organometallic compounds.
These compounds are used alone or as a mixture or polycondensate of a plurality of compounds. Among these, an organometallic compound containing zirconium or silicon is desirably used because it has a low residual potential and a small potential change due to the environment and a small potential change due to repeated use. In addition, the organometallic compound may be used alone or in combination of two or more, or may be used in combination with the above-described binder resin.

Examples of organosilane compounds (organometallic compounds containing silicon atoms) include vinyltrimethoxysilane, vinyltris (β-methoxyethoxysilane), γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyl-tris (β-methoxy). Ethoxy) silane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropylmethyldimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, N, N- Bis (β-hydroxy Ciethyl) -γ-aminopropyltriethoxysilane, γ-chloropropyltrimethoxysilane, and the like. Among these,
Vinyltriethoxysilane, vinyltris (β-methoxyethoxysilane), γ-methacryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, N- β- (aminoethyl) γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) γ-aminopropylmethyldimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, Silane coupling agents such as γ-mercaptopropyltrimethoxysilane and γ-chloropropyltrimethoxysilane are preferably used.

  In addition, as the undercoat layer, for example, a known undercoat layer such as the undercoat layer described in paragraphs 0113 to 0136 of JP-A-2008-075520 is used.

-Photosensitive layer: Charge transport layer-
Next, the photosensitive layer will be described below in this order, divided into a charge transport layer and a charge generation layer.
Examples of the charge transport material used for the charge transport layer include those shown below. That is, oxadiazole derivatives such as 2,5-bis (p-diethylaminophenyl) -1,3,4-oxadiazole, 1,3,5-triphenyl-pyrazoline, 1- [pyridyl- (2)]- Pyrazoline derivatives such as 3- (p-diethylaminostyryl) -5- (p-diethylaminostyryl) pyrazoline, triphenylamine, tri (p-methyl) phenylamine, N, N-bis (3,4-dimethylphenyl) biphenyl Aromatic tertiary amino compounds such as -4-amine, dibenzylaniline, 9,9-dimethyl-N, N-di (p-tolyl) fluorenon-2-amine, N, N′-diphenyl-N, N Aromatic tertiary diamino compounds such as' -bis (3-methylphenyl)-[1,1-biphenyl] -4,4'-diamine, 3- (4'-dimethylamino) 1,2,4-triazine derivatives such as phenyl) -5,6-di- (4′-methoxyphenyl) -1,2,4-triazine, 4-diethylaminobenzaldehyde-1,1-diphenylhydrazone, 4-diphenyl Aminobenzaldehyde-1,1-diphenylhydrazone, [p- (diethylamino) phenyl] (1-naphthyl) phenylhydrazone, 1-pyrenediphenylhydrazone, 9-ethyl-3-[(2methyl-1-indolinylimino) methyl Carbazole, 4- (2-methyl-1-indolinyliminomethyl) triphenylamine, 9-methyl-3-carbazole diphenylhydrazone, 1,1-di- (4,4′-methoxyphenyl) acrylaldehyde diphenylhydrazone , Β, β-bis (methoxyphenyl) vinyldiphenyl Hydrazone derivatives such as drazone, quinazoline derivatives such as 2-phenyl-4-styryl-quinazoline, benzofuran derivatives such as 6-hydroxy-2,3-di (p-methoxyphenyl) -benzofuran, p- (2,2-diphenyl) Hole transport materials such as α-stilbene derivatives such as vinyl) -N, N-diphenylaniline, enamine derivatives, carbazole derivatives such as N-ethylcarbazole, poly-N-vinylcarbazole and derivatives thereof are used. Or the polymer etc. which have the group containing the said compound in a principal chain or a side chain are mentioned. These charge transport materials are used alone or in combination of two or more.

  The binder resin used for the charge transport layer is not particularly limited, but it is desirable that the binder resin is particularly compatible with the charge transport material and has an appropriate strength.

  Examples of this binder resin include various polycarbonate resins including bisphenol A, bisphenol Z, bisphenol C, bisphenol TP and the like, copolymers thereof, polyarylate resins and copolymers thereof, polyester resins, methacrylic resins, acrylic resins, Polyvinyl chloride resin, polyvinylidene chloride resin, polystyrene resin, polyvinyl acetate resin, styrene-butadiene copolymer resin, vinyl chloride-vinyl acetate copolymer resin, vinyl chloride-vinyl acetate-maleic anhydride copolymer resin, silicone Resin, silicone-alkyd resin, phenol-formaldehyde resin, styrene-acrylic copolymer resin, ethylene-alkyd resin, poly-N-vinylcarbazole resin, polyvinyl butyral resin, polyphenylene ether resin, etc. And the like. These resins are used alone or as a mixture of two or more.

  The molecular weight of the binder resin used for the charge transport layer is selected depending on the film thickness of the photosensitive layer and the film forming conditions such as a solvent, but it is usually preferably within a range of 3000 to 300,000 in terms of viscosity average molecular weight. The range of 200,000 or less is more desirable.

  The charge transport layer is formed by applying and drying a solution in which the charge transport material and the binder resin are dissolved in an appropriate solvent. Examples of the solvent used for forming the coating solution for forming the charge transport layer include aromatic hydrocarbons such as benzene, toluene and chlorobenzene, ketones such as acetone and 2-butanone, methylene chloride, chloroform and ethylene chloride. And halogenated aliphatic hydrocarbons, cyclic or linear ethers such as tetrahydrofuran, dioxane, ethylene glycol and diethyl ether, or a mixed solvent thereof. The blending ratio between the charge transport material and the binder resin is preferably within the range of 10: 1 to 1: 5. The layer thickness of the charge transport layer is generally preferably in the range of 5 μm to 50 μm, and more preferably in the range of 10 μm to 40 μm.

The charge transport layer and / or the charge generation layer, which will be described later, are used for the purpose of suppressing deterioration of the photoreceptor due to ozone, oxidizing gas, light, or heat generated in the image forming apparatus. Additives such as stabilizers may be included.
Examples of the antioxidant include hindered phenols, hindered amines, paraphenylenediamines, arylalkanes, hydroquinones, spirochromans, spiroidanones or their derivatives, organic sulfur compounds, and organic phosphorus compounds.

The charge transport layer is formed, for example, by applying a solution obtained by dissolving the charge transport material and the binder resin described above in an appropriate solvent and drying the solution. Examples of the solvent used for preparing the coating solution for forming the charge transport layer include aromatic hydrocarbons such as benzene, toluene and chlorobenzene, ketones such as acetone and 2-butanone, and halogens such as methylene chloride, chloroform and ethylene chloride. Cyclic aliphatic hydrocarbons, cyclic or linear ethers such as tetrahydrofuran, dioxane, ethylene glycol and diethyl ether, or a mixed solvent thereof is used.
Silicone oil may be added to the charge transport layer forming coating solution as a leveling agent for improving the smoothness of the coating film to be coated and formed.

  The compounding ratio of the charge transport material and the binder resin is desirably 10: 1 to 1: 5 by mass ratio. The layer thickness of the charge transport layer is generally preferably in the range of 5 μm to 50 μm, and more preferably in the range of 10 μm to 30 μm.

  The coating solution for forming the charge transport layer can be applied by dip coating, ring coating, spray coating, bead coating, blade coating, roller coating, knife coating, curtain coating, depending on the shape and application of the photoreceptor. This is performed using a coating method such as a coating method. As for drying, it is desirable to heat-dry after touch drying at room temperature (for example, 20 ° C. or higher and 30 ° C. or lower). The heat drying is desirably performed in a temperature range of 30 ° C. or higher and 200 ° C. or lower for a time in the range of 5 minutes to 2 hours.

  In addition, as the charge transport layer, for example, a known charge transport layer such as a charge transport layer described in paragraphs 0137 to 0150 of JP-A-2008-075520 is used.

-Photosensitive layer: Charge generation layer-
The charge generation layer is formed by depositing a charge generation material by a vacuum deposition method or by applying a solution containing an organic solvent and a binder resin.

Examples of charge generation materials include amorphous selenium, crystalline selenium, selenium-tellurium alloy, selenium-arsenic alloy, and other selenium compounds; inorganic photoconductors such as selenium alloy, zinc oxide, and titanium oxide; Sensitized, various phthalocyanine compounds such as metal-free phthalocyanine, titanyl phthalocyanine, copper phthalocyanine, tin phthalocyanine, gallium phthalocyanine; Various organic pigments such as salts; or dyes are used.
In addition, these organic pigments generally have several types of crystals. In particular, phthalocyanine compounds have various crystal types including α type and β type. Any of these crystal forms may be used as long as it is a pigment capable of obtaining characteristics.

  Of the charge generation materials described above, phthalocyanine compounds are desirable. In this case, when the photosensitive layer is irradiated with light, the phthalocyanine compound contained in the photosensitive layer absorbs photons and generates carriers. At this time, since the phthalocyanine compound has high quantum efficiency, the absorbed photons are efficiently absorbed to generate carriers.

Further, among the phthalocyanine compounds, phthalocyanines shown in the following (1) to (3) are more preferable. That is,
(1) At least 7.6 °, 10.0 °, 25.2 °, 28.0 ° in the Bragg angle (2θ ± 0.2 °) of the X-ray diffraction spectrum using Cukα rays as the charge generation material Crystalline hydroxygallium phthalocyanine having a diffraction peak at the position.
(2) At least 7.3 °, 16.5 °, 25.4 °, 28.1 ° in the Bragg angle (2θ ± 0.2 °) of the X-ray diffraction spectrum using Cukα rays as the charge generation material Crystalline chlorogallium phthalocyanine having a diffraction peak at the position.
(3) Diffraction peaks at positions of at least 9.5 °, 24.2 °, and 27.3 ° in the Bragg angle (2θ ± 0.2 °) of the X-ray diffraction spectrum using Cukα rays as the charge generation material. A crystalline form of titanyl phthalocyanine.

  Since these phthalocyanine compounds have not only high photosensitivity but also high stability of photosensitivity, a photoreceptor having a photosensitive layer containing these phthalocyanine compounds is required to have high-speed image formation and reproducibility. It is suitable as a photoreceptor for a color image forming apparatus.

  Note that the peak intensity and position may slightly deviate from these values depending on the crystal shape and measurement method. However, if the X-ray diffraction patterns are basically the same, the same crystal type is assumed. To be judged.

Examples of the binder resin used for the charge generation layer include the following.
Namely, polycarbonate resin such as bisphenol A type or bisphenol Z type and its copolymer, polyarylate resin, polyester resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polystyrene resin, polyvinyl acetate resin, styrene-butadiene copolymer Resin, vinylidene chloride-acrylonitrile copolymer resin, vinyl chloride-vinyl acetate-maleic anhydride resin, silicone resin, silicone-alkyd resin, phenol-formaldehyde resin, styrene-alkyd resin, poly-N-vinylcarbazole, etc. .

  These binder resins are used alone or in combination of two or more. The mixing ratio of the charge generation material and the binder resin (charge generation material: binder resin) is preferably in the range of 10: 1 to 1:10 by mass ratio. In general, the thickness of the charge generation layer is desirably in the range of 0.01 μm to 5 μm, and more desirably in the range of 0.05 μm to 2.0 μm.

The charge generation layer may contain at least one electron accepting substance for the purpose of improving sensitivity, reducing residual potential, reducing fatigue during repeated use, and the like. Examples of the electron accepting material used in the charge generation layer include succinic anhydride, maleic anhydride, dibromomaleic anhydride, phthalic anhydride, tetrabromophthalic anhydride, tetracyanoethylene, tetracyanoquinodimethane, and o-dinitrobenzene. M-dinitrobenzene, chloranil, dinitroanthraquinone, trinitrofluorenone, peak phosphoric acid, o-nitrobenzoic acid, p-nitrobenzoic acid, phthalic acid and the like. Of these, fluorenone-based, quinone-based, and benzene derivatives having electron-withdrawing substituents such as Cl, CN, NO ₂ are particularly preferable.

As a method for dispersing the charge generating material in the resin, methods such as a roll mill, a ball mill, a vibrating ball mill, an attritor, a dyno mill, a sand mill, and a colloid mill are used.
Known organic solvents as coating solution solvents for forming the charge generation layer, for example, aromatic hydrocarbon solvents such as toluene and chlorobenzene, fats such as methanol, ethanol, n-propanol, iso-propanol, and n-butanol Aromatic alcohol solvents, ketone solvents such as acetone, cyclohexanone and 2-butanone, halogenated aliphatic hydrocarbon solvents such as methylene chloride, chloroform and ethylene chloride, cyclic or straight chain such as tetrahydrofuran, dioxane, ethylene glycol and diethyl ether And ether solvents such as methyl ether, methyl acetate, ethyl acetate, and n-butyl acetate.

  These solvents are used alone or in combination of two or more. When two or more kinds of solvents are mixed and used, for example, a solvent that dissolves the binder resin is used as the mixed solvent. However, when the photosensitive layer has a layer structure in which the charge transport layer and the charge generation layer are formed in this order from the conductive substrate side, charge generation is performed using a coating method that easily dissolves the lower layer, such as dip coating. When forming the layer, it is desirable to use a solvent that does not dissolve the lower layer such as the charge transport layer. In addition, when the charge generation layer is formed by using a spray coating method or a ring coating method with a relatively low erosion property of the lower layer, the selection range of the solvent is widened.

(Process cartridge and image forming apparatus)
FIG. 7 is a schematic configuration diagram illustrating an example of an image forming apparatus according to the present embodiment.
As shown in FIG. 7, the image forming apparatus 101 according to the present embodiment includes, for example, an electrophotographic photosensitive member 10 that rotates clockwise as indicated by an arrow a (the electrophotographic photosensitive member according to the present embodiment). And a charging device 20 (an example of a charging unit) that is provided above the electrophotographic photosensitive member 10 and is opposed to the electrophotographic photosensitive member 10 and charges the surface of the electrophotographic photosensitive member 10. An exposure device 30 (an example of an electrostatic latent image forming unit) that exposes the surface of the electrophotographic photoreceptor 10 to form an electrostatic latent image, and the electrostatic latent image formed by the exposure device 30 is included in the developer. A developing device 40 (an example of a developing unit) that forms a toner image on the surface of the electrophotographic photosensitive member 10 by adhering the toner to be moved, while traveling in the direction indicated by the arrow b while being in contact with the electrophotographic photosensitive member 10, On the surface of the photoconductor 10 Comprises an intermediate transfer member 50 belt-shaped for transferring the made toner image, and a cleaning device 70 for cleaning the surface of the electrophotographic photosensitive member 10 (an example of a cleaning unit).

  The charging device 20, the exposure device 30, the developing device 40, the intermediate transfer member 50, the lubricant supply device 60, and the cleaning device 70 are arranged in a clockwise direction on the circumference surrounding the electrophotographic photosensitive member 10. In this embodiment, a mode in which the lubricant supply device 60 is disposed inside the cleaning device 70 will be described. However, the present invention is not limited to this, and the lubricant supply device 60 is disposed separately from the cleaning device 70. It may be in the form.

  The intermediate transfer member 50 is held from the inside while being tensioned by the support rollers 50A and 50B, the back roller 50C, and the drive roller 50D, and is driven in the direction of the arrow b as the drive roller 50D rotates. At a position facing the electrophotographic photosensitive member 10 inside the intermediate transfer member 50, the intermediate transfer member 50 is charged to a polarity different from the charging polarity of the toner, and the electrophotographic photosensitive member 10 is placed on the outer surface of the intermediate transfer member 50. A primary transfer device 51 for adsorbing the upper toner is provided. On the outer side below the intermediate transfer member 50, the recording paper P (an example of a recording medium) is charged to a polarity different from the charged polarity of the toner, and the toner image formed on the intermediate transfer member 50 is placed on the recording paper P. A secondary transfer device 52 for transferring is provided to face the back roller 50C. These members for transferring the toner image formed on the electrophotographic photosensitive member 10 to the recording paper P correspond to an example of a transfer unit.

  Below the intermediate transfer member 50, a recording paper supply device 53 that supplies the recording paper P to the secondary transfer device 52 and a recording paper P on which the toner image is formed in the secondary transfer device 52 are conveyed. A fixing device 80 for fixing the toner image is provided.

  The recording paper supply device 53 includes a pair of transport rollers 53A and a guide slope 53B that guides the recording paper P transported by the transport rollers 53A toward the secondary transfer device 52. On the other hand, the fixing device 80 includes a fixing roller 81 that is a pair of heat rollers for fixing the toner image by heating and pressing the recording paper P onto which the toner image has been transferred by the secondary transfer device 52, and a fixing roller. And a conveyance conveyor 82 that conveys the recording paper P toward 81.

  The recording paper P is conveyed in the direction indicated by the arrow c by the recording paper supply device 53, the secondary transfer device 52, and the fixing device 80.

  The intermediate transfer member 50 is further provided with an intermediate transfer member cleaning device 54 having a cleaning blade for removing the toner remaining on the intermediate transfer member 50 after the toner image is transferred to the recording paper P in the secondary transfer device 52. Yes.

  Details of main components in the image forming apparatus 101 according to the present embodiment will be described below.

-Charging device-
Examples of the charging device 20 include a contact charger using a conductive charging roller, a charging brush, a charging film, a charging rubber blade, a charging tube, and the like. Further, examples of the charging device 20 include a non-contact type roller charger and a known charger such as a scorotron charger using a corona discharge or a corotron charger. As the charging device 20, a contact charger is preferable.
In this embodiment, even if a charger that applies a voltage in which an alternating current is superimposed on a direct current is used or a discharge product is likely to be generated, an electrophotography can be obtained even if such a method is adopted. Adhesion / deposition of discharge products on the photoreceptor 10 is suppressed, and white spots in the image are suppressed.

-Exposure device-
Examples of the exposure apparatus 30 include optical system devices that expose the surface of the electrophotographic photoreceptor 10 with light such as semiconductor laser light, LED light, and liquid crystal shutter light imagewise. The wavelength of the light source is preferably within the spectral sensitivity region of the electrophotographic photoreceptor 10. As the wavelength of the semiconductor laser, for example, near infrared having an oscillation wavelength around 780 nm is preferable. However, the present invention is not limited to this wavelength, and a laser having an oscillation wavelength of 600 nm or a laser having an oscillation wavelength of 400 nm to 450 nm as a blue laser may be used. Further, as the exposure apparatus 30, for example, a surface emitting laser light source of a multi-beam output type is also effective for color image formation.

-Developer-
The developing device 40 is disposed, for example, opposite to the electrophotographic photoreceptor 10 in the developing region, and includes, for example, a developing container 41 (developing device main body) that contains a two-component developer composed of toner and a carrier, and a replenishment device. A developer storage container (toner cartridge) 47. The developing container 41 includes a developing container main body 41A and a developing container cover 41B that closes the upper end thereof.

  The developing container main body 41A has, for example, a developing roll chamber 42A that accommodates the developing roll 42 therein, and is adjacent to the first stirring chamber 43A and the first stirring chamber 43A adjacent to the developing roll chamber 42A. Second agitating chamber 44A. Further, in the developing roll chamber 42A, for example, a layer thickness regulating member 45 for regulating the layer thickness of the developer on the surface of the developing roll 42 is provided when the developing container cover 41B is attached to the developing container main body 41A. Yes.

  The first stirring chamber 43A and the second stirring chamber 44A are partitioned by, for example, a partition wall 41C. Although not shown, the first stirring chamber 43A and the second stirring chamber 44A are arranged in the longitudinal direction of the partition wall 41C (developing device). (Longitudinal direction) Openings are provided at both ends, and the circulation stirring chamber (43A + 44A) is constituted by the first stirring chamber 43A and the second stirring chamber 44A.

  The developing roll 42 is disposed in the developing roll chamber 42 </ b> A so as to face the electrophotographic photoreceptor 10. Although not shown, the developing roll 42 is provided with a sleeve outside a magnetic roll (fixed magnet) having magnetism. The developer in the first stirring chamber 43A is adsorbed on the surface of the developing roll 42 by the magnetic force of the magnetic roll and is transported to the developing area. Further, the developing roller 42 has a roll shaft supported rotatably on the developing container main body 41A. Here, the developing roll 42 and the electrophotographic photoreceptor 10 rotate in the same direction, and the developer adsorbed on the surface of the developing roll 42 at the opposite portion is opposite to the traveling direction of the electrophotographic photoreceptor 10. It is conveyed from the direction to the development area.

  Further, a bias power source (not shown) is connected to the sleeve of the developing roll 42 so that a developing bias is applied (in this embodiment, a direct current component is applied so that an alternating electric field is applied to the developing region. (A bias in which an alternating current component (DC) is superimposed on (AC) is applied).

  In the first stirring chamber 43A and the second stirring chamber 44A, a first stirring member 43 (stirring / conveying member) and a second stirring member 44 (stirring / conveying member) that convey the developer while stirring are disposed. The first stirring member 43 includes a first rotating shaft that extends in the axial direction of the developing roll 42, and an agitating / conveying blade (protrusion) that is helically fixed to the outer periphery of the rotating shaft. Similarly, the second agitating member 44 includes a second rotating shaft and an agitating / conveying blade (protrusion). The stirring member is rotatably supported by the developing container main body 41A. The first stirring member 43 and the second stirring member 44 are arranged such that the developer in the first stirring chamber 43A and the second stirring chamber 44A is conveyed in the opposite directions by rotation thereof. .

  One end of a replenishment conveyance path 46 for supplying replenishment developer including replenishment toner and replenishment carrier to the second agitation chamber 44A is connected to one end side in the longitudinal direction of the second agitation chamber 44A. The other end of the replenishment conveyance path 46 is connected to a replenishment developer storage container 47 that contains a replenishment developer.

  In this manner, the developing device 40 supplies the replenishment developer from the replenishment developer storage container (toner cartridge) 47 to the development device 40 (second stirring chamber 44A) through the replenishment conveyance path 46.

Here, the developer used in the developing device 40 will be described.
As the developer, a two-component developer including a toner and a carrier is employed.

First, the toner will be described.
The toner includes, for example, toner particles containing a binder resin, a colorant, and, if necessary, other additives such as a release agent, and external additives as necessary.

The toner particles have an average shape factor (shape factor = (ML ² / A) × (π / 4) × 100), and ML represents the maximum length of the particles, where A represents the maximum length of the particles (Representing the projected area) is preferably from 100 to 150, more preferably from 105 to 145, and even more preferably from 110 to 140. Further, the toner preferably has a volume average particle diameter of 3 μm or more and 12 μm or less, more preferably 3.5 μm or more and 10 μm or less, and further preferably 4 μm or more and 9 μm or less.

  The toner particles are not particularly limited by the production method, and for example, a kneading and pulverizing method in which a binder resin, a colorant and a release agent, and a charge control agent and the like are added, if necessary, are kneaded, pulverized, and classified; A method of changing the shape of the particles obtained by the kneading and pulverization method by mechanical impact force or thermal energy; the polymerization monomer of the binder resin is emulsion-polymerized, the formed dispersion, the colorant and the release agent Emulsion polymerization aggregation method to obtain a toner particle by mixing a mold agent and, if necessary, a dispersion of a charge control agent, and agglomerating and heat-fusing; a polymerizable monomer for obtaining a binder resin, and coloring Suspension polymerization method in which a solution of an agent, a release agent and, if necessary, a charge control agent is suspended in an aqueous solvent for polymerization; a binder resin, a colorant and a release agent, and if necessary, a charge control agent Toner particles produced by a solution suspension method in which a solution such as a liquid is suspended in an aqueous solvent and granulated There will be used.

  Further, a known method such as a production method in which the toner particles obtained by the above method are used as a core, and agglomerated particles are further adhered and heated and fused to give a core-shell structure is used. The toner production method is preferably a suspension polymerization method, an emulsion polymerization aggregation method, or a dissolution suspension method in which an aqueous solvent is used from the viewpoint of shape control and particle size distribution control, and an emulsion polymerization aggregation method is particularly desirable.

  The toner is produced by mixing the toner particles and the external additive with a Henschel mixer or a V blender. Further, when the toner particles are produced by a wet method, they may be externally added by a wet method.

  On the other hand, as the carrier, iron powder, glass beads, ferrite powder, nickel powder, or the like coated with a resin is used. Further, the mixing ratio of the carrier and the toner is not particularly limited and is set within a known range.

-Transfer device-
Examples of the primary transfer device 51 and the secondary transfer device 52 include a contact transfer charger using a belt, a roller, a film, a rubber blade, and the like, a scorotron transfer charger using a corona discharge, a corotron transfer charger, and the like. A transfer charger known per se can be used.

  As the intermediate transfer member 50, a belt-like member (intermediate transfer belt) such as polyimide, polyamideimide, polycarbonate, polyarylate, polyester, rubber containing a conductive agent is used. Further, as the form of the intermediate transfer member, a cylindrical one is used in addition to the belt shape.

-Cleaning device-
The cleaning device 70 includes a housing 71, a cleaning blade 72 disposed so as to protrude from the housing 71, and a lubricant supply device 60 disposed downstream of the cleaning blade 72 in the rotation direction of the electrophotographic photosensitive member 10. , Including.
The cleaning blade 72 may be supported by the end portion of the casing 71 or may be separately supported by a support member (holder). The form supported at the end of 71 is shown.

First, the cleaning blade 72 will be described.
Examples of the material constituting the cleaning blade 72 (the cleaning layer 72A and the back layer 72B) include urethane rubber, silicon rubber, fluorine rubber, propylene rubber, and butadiene rubber. Among these, urethane rubber is preferable.
The urethane rubber (polyurethane) is not particularly limited as long as it is usually used for forming polyurethane, for example, a urethane prepolymer comprising a polyol such as a polyester polyol such as polyethylene adipate or polycaprolactone and an isocyanate such as diphenylmethane diisocyanate. For example, it is preferable to use a crosslinking agent such as 1,4-butanediol, trimethylolpropane, ethylene glycol or a mixture thereof as a raw material.

Next, the lubricant supply device 60 will be described.
The lubricant supply device 60 is provided, for example, inside the cleaning device 70 and upstream of the cleaning blade 72 in the rotation direction of the electrophotographic photosensitive member 10.

  The lubricant supply device 60 includes, for example, a rotating brush 61 disposed in contact with the electrophotographic photosensitive member 10 and a solid lubricant 62 disposed in contact with the rotating brush 61. . In the lubricant supply device 60, the rotating brush 61 is rotated while being in contact with the solid lubricant 62, whereby the lubricant 62 adheres to the rotating brush 61, and the attached lubricant 62 becomes the electrophotographic photosensitive member. The film of the lubricant 62 is formed on the surface 10.

  The lubricant supply device 60 is not limited to the above form, and may be a form that employs a rubber roller instead of the rotating brush 61, for example.

  Next, the operation of the image forming apparatus 101 according to the present embodiment will be described. First, the electrophotographic photoreceptor 10 rotates along the direction indicated by the arrow a, and at the same time is negatively charged by the charging device 20.

  The electrophotographic photoreceptor 10 whose surface is negatively charged by the charging device 20 is exposed by the exposure device 30, and a latent image is formed on the surface.

  When the portion where the latent image is formed on the electrophotographic photoreceptor 10 approaches the developing device 40, the developing device 40 (developing roll 42) attaches toner to the latent image and forms a toner image.

  When the electrophotographic photosensitive member 10 on which the toner image is formed further rotates in the direction of arrow a, the toner image is transferred to the outer surface of the intermediate transfer member 50.

  When the toner image is transferred to the intermediate transfer member 50, the recording paper P is supplied to the secondary transfer device 52 by the recording paper supply device 53, and the toner image transferred to the intermediate transfer member 50 is transferred by the secondary transfer device 52. Transferred onto the recording paper P. As a result, a toner image is formed on the recording paper P.

  The toner image is fixed on the recording paper P on which the image is formed by the fixing device 80.

  Here, after the toner image is transferred to the intermediate transfer member 50, the electrophotographic photosensitive member 10 is transferred, and then the lubricant supply device 60 supplies the lubricant 62 to the surface of the electrophotographic photosensitive member 10. A film of the lubricant 62 is formed on the surface of the photographic photoreceptor 10. Thereafter, the toner and discharge products remaining on the surface are removed by the cleaning blade 72 of the cleaning device 70. Then, the electrophotographic photosensitive member 10 from which the transfer residual toner and discharge products are removed in the cleaning device 70 is charged again by the charging device 20 and is exposed in the exposure device 30 to form a latent image.

Further, for example, as illustrated in FIG. 8, the image forming apparatus 101 according to the present embodiment includes an electrophotographic photosensitive member 10, a charging device 20, a developing device 40, a lubricant supply device 60, and a cleaning in a housing 11. A configuration including a process cartridge 101A that integrally accommodates the apparatus 70 may be employed. The process cartridge 101A integrally contains a plurality of members and is attached to and detached from the image forming apparatus 101. In the image forming apparatus 101 shown in FIG. 8, the developing device 40 is not provided with the replenishment developer storage container 47.
The configuration of the process cartridge 101A is not limited to this. For example, the process cartridge 101A only needs to include at least the electrophotographic photoreceptor 10, and for example, the charging device 20, the exposure device 30, the developing device 40, the primary transfer device 51, the lubrication At least one selected from the agent supply device 60 and the cleaning device 70 may be provided.

  In addition, the image forming apparatus 101 according to the present embodiment is not limited to the above-described configuration. For example, the cleaning is performed around the electrophotographic photosensitive member 10 and downstream of the primary transfer device 51 in the rotation direction of the electrophotographic photosensitive member 10. A first neutralization device may be provided on the upstream side of the rotation direction of the electrophotographic photosensitive member relative to the device 70 so that the polarity of the remaining toner is aligned and easily removed with a cleaning brush. Even if the second static eliminating device for neutralizing the surface of the electrophotographic photosensitive member 10 is provided on the downstream side in the rotational direction of the electrophotographic photosensitive member relative to the upstream side in the rotational direction of the electrophotographic photosensitive member relative to the charging device 20. Good.

  Further, the image forming apparatus 101 according to the present embodiment is not limited to the above-described configuration, and may employ a known configuration, for example, a method of directly transferring a toner image formed on the electrophotographic photosensitive member 10 to the recording paper P. Alternatively, a tandem image forming apparatus may be employed.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. In the following examples, “part” means part by mass.

[Example 1]
An organic photoreceptor in which an undercoat layer, a charge generation layer, and a charge transport layer were laminated in this order on an aluminum (Al) substrate was prepared by the procedure described below.

<Formation of undercoat layer>
20 parts by mass of a zirconium compound (trade name: Organotix ZC540 manufactured by Matsumoto Pharmaceutical Co., Ltd.), 2.5 parts by mass of a silane compound (trade name: A1100 manufactured by Nihon Unicar Co., Ltd.), polyvinyl butyral resin (trade name: S-REC BM- manufactured by Sekisui Chemical Co., Ltd.) S) A solution obtained by stirring and mixing 10 parts by weight and 45 parts by weight of butanol was applied to the surface of an Al substrate having an outer diameter of 60 mm and dried by heating at 150 ° C. for 10 minutes, whereby the layer thickness was 1.0 μm. A layer was formed.

<Formation of charge generation layer>
Next, a mixture obtained by mixing 1 part by mass of chlorogallium phthalocyanine as a charge generation material with 1 part by mass of polyvinyl butyral (trade name: S-REC BM-S manufactured by Sekisui Chemical Co., Ltd.) and 100 parts by mass of n-butyl acetate. Dispersion with a glass bead with a paint shaker for 1 hour gave a dispersion for forming a charge generation layer.
This dispersion was applied on the undercoat layer by the dipping method and then dried at 100 ° C. for 10 minutes to form a charge generation layer having a layer thickness of 0.15 μm.

<Formation of charge transport layer>
Next, 2 parts by mass of a compound represented by the following structural formula (1) and 3 parts by mass of a polymer compound (viscosity average molecular weight: 39000) whose repeating unit is represented by the following structural formula (2) are mixed with chlorobenzene 20 A charge transport layer forming coating solution was obtained by dissolving in mass parts.

  This coating solution is applied onto the charge generation layer by an immersion method, heated at 110 ° C. for 40 minutes to form a charge transport layer having a layer thickness of 20 μm, and the undercoat layer, the charge generation layer and the charge transport layer are formed on the Al substrate. As a result, an organic photoreceptor (hereinafter sometimes referred to as “non-coated photoreceptor (1)”) in which layers were formed in this order was obtained.

<Formation of protective layer>
(Formation of second layer)
The second layer is formed on the surface of the non-coated photoreceptor (1) by forming a film forming apparatus (shower nozzle 216 having a structure shown in FIG. 4 into a frame 224 having an elongated hole (slit) opening 224A. Nozzle type [slit type] provided).
First, the non-coated photoreceptor (1) is 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 is evacuated through the exhaust port 211 until the pressure becomes 0.1 Pa. did.
Next, He-diluted 20% oxygen gas (flow rate 27 sccm) and hydrogen gas (flow rate 1000 sccm) are introduced from the gas introduction tube 220 into the high-frequency discharge tube portion 221 provided with the plate electrode 219 having a diameter of 85 mm. A 13.56 MHz radio wave was set to an output of 150 W by a supply unit 218 and a matching circuit (not shown in FIG. 4), and matching was performed with a tuner to discharge from the plate electrode 219. The reflected wave at this time was 0 W.
Next, trimethylgallium gas (flow rate: 3.0 sccm) was introduced from the shower nozzle 216 to the plasma diffusion portion 217 in the film formation chamber 210 via the gas introduction tube 215. At this time, the reaction pressure in the film forming chamber 210 measured with a Baratron vacuum gauge was 25 Pa.
In this state, the non-coated photoconductor (1) was formed for 80 minutes while rotating at a speed of 500 rpm, and a second layer having a thickness of 2.0 μm was formed on the surface of the charge transport layer of the non-coated photoconductor (1).

(Formation of the first layer)
Next, the high-frequency discharge was stopped, and He-diluted 20% oxygen gas (flow rate: 14 sccm), hydrogen gas (flow rate: 500 sccm), high-frequency power (100 W), and high-frequency discharge was performed again. Next, trimethylgallium gas (flow rate 2.0 sccm) was introduced. At this time, the reaction pressure was 25 Pa.
In this state, the non-coated photoreceptor (1) in which the second layer is sequentially formed is formed for 60 minutes while rotating at a speed of 500 rpm, and a first layer having a thickness of 1.0 μm is formed on the second layer. Formed.

Thus, an electrophotographic photosensitive member (electrophotographic photosensitive member with a protective layer) having the second layer and the first layer in this order as protective layers on the charge transport layer of the non-coated photosensitive member (1) was obtained.
It should be noted that when the protective layer (second layer and first layer) was formed, the non-coated photoreceptor (1) was not heat-treated. In addition, in order to monitor the temperature at the time of film formation, the color of the temperature measurement sticker (made by Wahl, Temp Plate P / N101) previously attached to the surface of the non-coated photoreceptor before film formation is It was 45 degreeC when it confirmed after film-forming of 1 layer.

In addition, the layer thickness of the first layer and the layer thickness of the second layer were obtained by stylus step measurement using the following sample film for analysis.
As a substrate on which the sample film for analysis was formed, a Si wafer having a thickness of 400 μm cut into 5 mm × 10 mm was used.
A polyimide adhesive tape is applied to a part of the surface of the Si wafer, and the sample film for analysis of the first layer is formed on the surface on which the adhesive tape is attached under the same conditions as the film formation of the first layer. Formed.
Next, the adhesive tape was peeled off, and a non-film-formed part (location where the adhesive tape was applied) and a film-attached part (location where the adhesive tape was not applied) were provided on the Si wafer surface.
Next, the level difference between the non-film-deposited part and the film-deposited part was measured with a stylus level measuring device (Surfcom 550A manufactured by Tokyo Seimitsu Co., Ltd.) to determine the layer thickness of the first layer.
The layer thickness of the second layer was also determined by the same method as the layer thickness of the first layer.

[Examples 2 to 12, Comparative Examples 1 to 4]
According to Tables 1 to 3, He diluted 20% oxygen gas flow rate (expressed as O ₂ gas flow rate), hydrogen gas flow rate (expressed as H ₂ gas flow rate), trimethylgallium gas flow rate (expressed as TMG gas flow rate), high frequency power, Except for changing the film formation conditions such as the film formation time, the second layer and the first layer were sequentially formed on the non-coated photoreceptor (1) in the same manner as in Example 1, and the protective layer was formed. Thus, an electrophotographic photosensitive member was obtained.
However, in the comparative example, in the film forming apparatus having the configuration shown in FIG. 4, the electrophotographic photosensitive member is formed by forming a protective layer in a nozzle type [shower type] in which the frame body 224 is removed from the shower nozzle 216). Obtained.

[Comparative Example 5]
An electrophotographic photosensitive member was obtained in accordance with the method described in Example 13 of JP2011-028218A (Patent Document 3).

[Comparative Example 6]
An electrophotographic photosensitive member was obtained according to the method described in Example 1 of JP2011-197571A (Patent Document 4).

[Evaluation]
The electrophotographic photosensitive member with a protective layer obtained in each example was evaluated for characteristics and functions. The evaluation results are shown in Tables 4-6.

(Characteristic evaluation)
In the characteristic evaluation, the first layer of the protective layer is measured on the outer peripheral surface of the obtained electrophotographic photosensitive member, and the second layer is measured on the outer peripheral surface of the obtained electrophotographic photosensitive member. Was measured for the exposed second layer.

-Composition-
For each layer (first layer, second layer sample film) constituting the protective layer, the composition of the film is Rutherford Back Scattering (RBS), Hydrogen Forward Scattering (HFS) and EDS (Energy Dispersion Type) X-ray analysis method).
Specifically, according to the following method, the maximum value and the minimum value of the atomic ratio [O / Ga] were measured, and the average value [(maximum value + minimum value) / 2] was measured. In addition, the contents of hydrogen and carbon were also measured.
The density unevenness of the halftone image is present in a periodic band shape in the rotation axis direction of the electrophotographic photosensitive member with a protective layer, and the position corresponding to the center of the density unevenness band and the center of the two density unevenness bands arranged side by side. The composition of the protective layer at a position corresponding to the middle of each was measured.

-Light absorption edge energy-
About each layer (1st layer, 2nd layer sample film) which comprises a protective layer, the light absorption edge energy obtained from the wavelength from which an absorption coefficient is set to 1 * 10 < ^{6 >} (m <^-1> ) was measured by the spectrum. .
Specifically, according to the following method, FE1, FE1 (maximum value), FE1 (minimum value) of the first layer, FE2, FE2 (maximum value), and FE2 (minimum value) of the second layer were measured.
The density unevenness of the halftone image is present in a periodic band shape in the rotation axis direction of the electrophotographic photosensitive member with a protective layer, and the position corresponding to the center of the density unevenness band and the center of the two density unevenness bands arranged side by side. The light absorption energy of the protective layer at a position corresponding to the middle of each was measured.

-Maximum diameter and number of protrusions on the outer peripheral surface of the protective layer-
The maximum diameter and number of protrusions on the outer peripheral surface of the protective layer were measured according to the following method.
Observe the electrophotographic photosensitive member with a protective layer using the Olympus laser microscope OLS-1000, and make the maximum diameter with the diameter of the circle circumscribing the protruding portion on the outer peripheral surface of the protective layer, and the protruding portion with 10 fields on the photosensitive member Was divided by the observation area to obtain the number.

(Function evaluation)
-Halftone image density unevenness-
The density unevenness of the halftone image was evaluated as follows.
An electrophotographic photosensitive member with a protective layer is attached to a DocuCenter Color 500 manufactured by Fuji Xerox Co., Ltd., and it is a half of 200 LPI (200 lines per inch) area coverage 30% in a low temperature and low humidity environment (10 ° C., 15% RH). 100 continuous tone images were printed, and the resulting images were evaluated for image density unevenness according to the following evaluation criteria.
The evaluation criteria are as follows.
-Evaluation criteria-
A: No density unevenness is observed even at 100 sheets.
B: In printing exceeding 90 sheets, density unevenness is slightly observed, but is within a practically acceptable range.
C: Density unevenness is observed after printing exceeding 70 sheets.
D: In printing of 70 sheets or less, density unevenness appears at first glance, which exceeds the practically allowable range.

-Residual potential-
First, exposure light (light source: semiconductor laser, wavelength 780 nm, output 5 mW) is applied to the electrophotographic photosensitive member (non-coated photosensitive member) before forming the protective layer and the electrophotographic photosensitive member with protective layer. The residual potential of the surface after irradiation was measured while being negatively charged to −700 V by a scorotron charger while rotating at 40 rpm while scanning the surface of the photoreceptor.

-Decrease in sensitivity-
First, the electrophotographic photosensitive member with a protective layer was negatively charged to −700 V by a scorotron charger according to the method described above.
Next, the negatively charged electrophotographic photosensitive member with a protective layer is exposed to light for exposure (light source: semiconductor laser, wavelength 780 nm, output 5 mW) to remove static electricity, and the potential decay rate (V · m ² / mJ) and determined as the sensitivity A (V · m ² / mJ) of the electrophotographic photosensitive member with a protective layer.

The sensitivity B (V · m ² / mJ) of the electrophotographic photosensitive member (non-coated photosensitive member) before forming the protective layer was measured in the same manner as the measurement of the sensitivity of the electrophotographic photosensitive member with the protective layer.
The rate of decrease in sensitivity due to protective layer formation was determined by the following formula.
Formula: Reduction rate of sensitivity due to protective layer formation (%) = ((sensitivity B−sensitivity A) / sensitivity B) × 100

Next, the wavelength of light for exposure was changed from 100 nm to 800 nm at 100 nm intervals, and the rate of decrease in sensitivity (%) due to protective layer formation was determined for each wavelength.
From the sensitivity reduction rate (%) at each wavelength obtained as described above, the sensitivity reduction due to protective layer formation was evaluated according to the following evaluation criteria.
The evaluation criteria are as follows.
A: The rate of decrease in sensitivity due to the formation of the protective layer was less than 10% over the entire wavelength region, and the decrease in sensitivity due to the formation of the protective layer was suppressed.
B: Although the rate of decrease in sensitivity due to the formation of the protective layer is 10% or more and less than 30% over the entire wavelength region, the decrease in sensitivity due to the formation of the protective layer was within a practically acceptable range.
C: The rate of decrease in sensitivity at a wavelength of 800 nm was 30% or more and 35% or less, and the decrease in sensitivity due to the formation of the protective layer was within a practically acceptable range.
D: The rate of decrease in sensitivity at a wavelength of 800 nm exceeded 35%, and the decrease in sensitivity due to the formation of the protective layer exceeded the practically acceptable range.

  From the above results, it can be seen that the present example obtained better results for evaluation of density unevenness, residual potential, and sensitivity reduction of the halftone image as compared with the comparative example.

DESCRIPTION OF SYMBOLS 1 Substrate, 2 Photosensitive layer, 2A Charge generation layer, 2B Charge transport layer, 3 Protective layer, 4 Undercoat layer, 210 Deposition chamber, 211 Exhaust port, 212 Substrate rotating part, 213 Substrate support member, 214 Substrate, 215, 220 Gas introduction pipe, 216 Shower nozzle, 216A nozzle hole, 217 Plasma diffusion part, 218 High frequency power supply part, 219 Flat plate electrode, 221 High frequency discharge pipe part, 222 High frequency coil, 223 Quartz tube, 224 Frame body, 224A Slotted shape (Slit-like) opening, 3A first region, 3B second region, 3C third region, 3D first layer, 3E second layer, 3F third layer, 3G intermediate layer, 10 electrophotography Photoconductor, 10A Electrophotographic photosensitive member, 10B Electrophotographic photosensitive member, 20 Charging device, 30 Exposure device, 40 Developing device, 41 Developing container, 41A Developing container Main body, 41B Developing container cover, 41C Wall, 42 Developing roll, 42A Developing roll chamber, 43 Stirring member, 43A Stirring chamber, 44 Stirring member, 44A Stirring chamber, 45 Layer thickness regulating member, 46 Replenishment transport path, 47 Replenishing development Agent storage container, 50 intermediate transfer member, 50A support roller, 50B support roller, 50C back roller, 50D drive roller, 51 primary transfer device, 52 secondary transfer device, 53 recording paper supply device, 53A transport roller, 53B guide slope, 54 Intermediate transfer member cleaning device, 70 Cleaning device, 71 Case, 72 Cleaning blade, 80 Fixing device, 81 Fixing roller, 82 Conveyor, 101 Image forming device, 101A Process cartridge,

Claims (5)

A substrate;
A photosensitive layer provided on the substrate;
A protective layer provided on the photosensitive layer and containing oxygen and gallium, the first region existing on the outer peripheral surface side, the first region existing closer to the substrate than the first region, A second region having a larger atomic ratio [oxygen / gallium] than that of the first region;
With
As each light absorption edge energy obtained from a wavelength having an absorption coefficient of 1 × 10 ⁶ (m ⁻¹ ) in each region, the average value of the light absorption edge energy in the first region [(maximum value + minimum value). / 2] is FE1, the average value [(maximum value + minimum value) / 2] of the light absorption edge energy in the second region is FE2, and the maximum value of the light absorption edge energy in the second region is FE2 (maximum. Value), an electrophotographic photosensitive member satisfying the following relational expressions (1) and (2), where FE2 (minimum value) is the minimum value of light absorption edge energy in the second region.
Relational expression (1): 0.5 eV ≦ FE2-FE1 ≦ 1.5 eV
Relational expression (2): FE2 (maximum value) −FE2 (minimum value) ≦ 0.5 eV   2. The electrophotographic photosensitive member according to claim 1, wherein the difference between the maximum value and the minimum value of the atomic ratio [oxygen / gallium] in the second region is 0.1 or less. A protrusion on the outer peripheral surface of the protective layer;
3. The electrophotographic photosensitive member according to claim 1, wherein the maximum diameter of the protrusions is 2 μm or less, and the number of the protrusions per unit area of the outer peripheral surface of the protective layer is 5000 / mm ² or less. body. The electrophotographic photosensitive member according to any one of claims 1 to 3,
A process cartridge that is detachable from the image forming apparatus. An electrophotographic photosensitive member according to any one of claims 1 to 3,
Charging means for charging the electrophotographic photoreceptor;
Latent image forming means for forming a latent image on the surface of the charged electrophotographic photosensitive member;
Developing means for developing a latent image formed on the surface of the electrophotographic photosensitive member with toner to form a toner image;
Transfer means for transferring a toner image formed on the surface of the electrophotographic photosensitive member to a recording medium;
An image forming apparatus.